THIS WARRANT AND THE UNDERLYING SECURITIES HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE “ACT”), OR UNDER THE SECURITIES LAWS OF ANY STATE. THESE SECURITIES MAY NOT BE OFFERED, SOLD OR OTHERWISE TRANSFERRED, PLEDGED OR HYPOTHECATED EXCEPT AS PERMITTED UNDER THE ACT AND APPLICABLE STATE SECURITIES LAWS IN ACCORDANCE WITH APPLICABLE REGISTRATION REQUIREMENTS OR AN EXEMPTION THEREFROM. THE ISSUER OF THESE SECURITIES MAY REQUIRE AN OPINION OF COUNSEL REASONABLY SATISFACTORY TO THE ISSUER THAT SUCH OFFER, SALE, TRANSFER, PLEDGE OR HYPOTHECATION OTHERWISE COMPLIES WITH THE ACT AND ANY APPLICABLE STATE SECURITIES LAWS. THIS WARRANT MUST BE SURRENDERED TO THE COMPANY OR ITS TRANSFER AGENT AS A CONDITION PRECEDENT TO THE SALE, TRANSFER, PLEDGE OR HYPOTHECATION OF ANY INTEREST IN ANY OF THE SECURITIES REPRESENTED HEREBY.

THIS CERTIFIES THAT, for value received, YA II PN, Ltd., or its registered assigns (the “Holder”), is entitled, subject to the provisions and upon the terms and conditions set forth herein, to purchase from ESS Tech, Inc., a Delaware corporation (the “Company”), shares of the Company’s common stock, $0.0001 par value per share (the “Shares”), in the amounts, at such times and at the price per share set forth in Section 1. The term “Warrant” as used herein shall include this Warrant and any warrants delivered in substitution or exchange therefor as provided herein. This Warrant is issued in connection with the issuance by the Company of that certain Promissory Note on October 14, 2025 (the “Note”).

The following is a statement of the rights of the Holder and the conditions to which this Warrant is subject, and to which Holder, by acceptance of this Warrant, agrees:

1.Number and Price of Shares; Exercise Period.

(a)Number of Shares. Subject to any previous exercise of the Warrant, the Holder shall have the right to purchase up to 1,052,104 Shares (the “Warrant Shares”), as may be adjusted pursuant hereto, prior to (or in connection with) the expiration of this Warrant as provided in Section 7.

(b)Exercise Price. The exercise price per Share shall be equal to $9.98, subject to adjustment pursuant hereto (the “Exercise Price”).

(c)Exercise Period. This Warrant shall be exercisable, in whole or in part, on or after the date hereof and prior to (or in connection with) the expiration of this Warrant as set forth in Section 7.

2.Exercise of the Warrant.

(a)Exercise. The purchase rights represented by this Warrant may be exercised at the election of the Holder, in whole or in part, in accordance with Section 1, by:

(1)the tender to the Company at its principal office (or such other office or agency as the Company may designate) of a notice of exercise in the form of Exhibit A (the “Notice of Exercise”), duly completed and executed by or on behalf of the Holder, together with the surrender of this Warrant; and

(2)the payment to the Company of an amount equal to (x) the Exercise Price multiplied by (y) the number of Shares being purchased, by (a) wire transfer or certified, cashier’s or other check acceptable to the Company and payable to the order of the Company; (b) surrender and cancellation of promissory notes or other instruments representing indebtedness of the Company to the Holder; or (c) a combination of (a) and (b).

(b)Net Issue Exercise. In lieu of exercising this Warrant pursuant to Section 2(a)(2), if (1) the fair market value of one Share is greater than the Exercise Price (at the date of calculation as set forth below) and (2) an Event of Default as defined in Section 4 of the Note has occurred and is continuing, the Holder may elect to receive a number of Shares equal to the value of this Warrant (or of any portion of this Warrant being canceled) by surrender of this Warrant at the principal office of the Company (or such other office or agency as the Company may designate) together with a properly completed and executed Notice of Exercise reflecting such election, in which event the Company shall issue to the Holder that number of Shares computed using the following formula:

Where:

(c)Stock Certificates. The rights under this Warrant shall be deemed to have been exercised and the Shares issuable upon such exercise shall be deemed to have been issued immediately prior to the close of business on the date this Warrant is exercised in accordance with its terms, and the person entitled to receive the Shares issuable upon such exercise shall be treated for all purposes as the holder of record of such Shares as of the close of business on such date. As promptly as reasonably practicable on or after such date, the Company shall issue and deliver to the person or persons entitled to receive the same a certificate or certificates (or a notice of issuance of uncertificated shares, if applicable) for that number of shares issuable upon such exercise. In the event that the rights under this Warrant are exercised in part and have not expired, the Company shall execute and deliver a new Warrant reflecting the number of Shares that remain subject to this Warrant.

(d)No Fractional Shares or Scrip. No fractional shares or scrip representing fractional shares shall be issued upon the exercise of the rights under this Warrant. In lieu of such fractional share to which the Holder would otherwise be entitled, the Company shall make a cash payment equal to the Exercise Price multiplied by such fraction.

(e)Reservation of Stock. The Company agrees during the term the rights under this Warrant are exercisable to take all reasonable action to reserve and keep available from its authorized and unissued shares of common stock for the purpose of effecting the exercise of this Warrant such number of shares as shall from time to time be sufficient to effect the exercise of the rights under this Warrant. The Company represents and warrants that all shares that may be issued upon the exercise of this Warrant will, when issued in accordance with the terms hereof, be validly issued, fully paid and nonassessable.

(f)Share Delivery. On or before the first (1st) Trading Day following the date on which the Holder has delivered the applicable Exercise Notice, the Company shall transmit by electronic mail an acknowledgment of confirmation of receipt of the Exercise Notice, to the Holder and the Company’s transfer agent (the “Transfer Agent”). So long as the Holder delivers the Aggregate Exercise Price (or notice of a Cashless Exercise, if applicable) on or prior to the first (1st) Trading Day following the date on which the Exercise Notice has been delivered to the Company, then on or prior to the number of Trading Days comprising the Standard Settlement Period following the date on which the Exercise Notice has been delivered to the Company, or, if the Holder does not deliver the Aggregate Exercise Price (or notice of a Cashless Exercise, if applicable) on or prior to the first (1st) Trading Day following the date on which the Exercise Notice has been delivered to the Company, then on or prior to the first (1st) Trading Day following the date on which the Aggregate Exercise Price (or notice of a Cashless Exercise, if applicable) is delivered (such earlier date, or if later, the earliest day on which the Company is required to deliver Warrant Shares pursuant to this Section 2(f), the “Share Delivery Date”), the Company shall (X) provided that the Transfer Agent is participating in The Depository Trust Company (“DTC”) Fast Automated Securities Transfer Program, credit such aggregate number of Warrant Shares to which the Holder is entitled pursuant to such exercise to the Holder’s or its designee’s balance account with DTC through its Deposit / Withdrawal At Custodian system, or (Y) if the Transfer Agent is not participating in the DTC Fast Automated Securities Transfer Program, issue and dispatch by overnight courier to the address as specified in the Exercise Notice, a certificate or evidence of a credit book entry of shares, registered in the name of the Holder or its designee, for the number of Warrant Shares to which the Holder is entitled pursuant to such exercise. The Company shall be responsible for all fees and expenses of the Transfer Agent and all fees and expenses with respect to the issuance of Warrant Shares via DTC, if any, including without limitation for same day processing. On the Share Delivery Date, the Holder shall be deemed for all corporate purposes to have become the holder of record and beneficial owner of the Warrant Shares with respect to which this Warrant has been exercised, irrespective of the date such Warrant Shares are credited to the Holder’s DTC account or the date of delivery of the certificates evidencing such Warrant Shares, as the case may be. If this Warrant is physically delivered to the Company in connection with any exercise pursuant to this Section 2(f) and the number of Warrant Shares represented by this Warrant submitted for exercise is greater than the number of Warrant Shares being acquired upon an exercise, then the Company shall as soon as practicable and in no event later than three (3) Trading Days after any exercise and at its own expense, issue and deliver to the Holder (or its designee) a new Warrant representing the right to purchase the number of Warrant Shares issuable immediately prior to such exercise under this Warrant, less the number of Warrant Shares with respect to which this Warrant is exercised. No fractional Warrant Shares are to be issued upon the exercise of this Warrant, but rather the number of Warrant Shares to be issued shall be rounded down to the nearest whole number. Issuance of Warrant Shares shall be made without charge to the Holder for any issue or transfer tax or any incidental expense in respect of the issuance of such Warrant Shares, all of which taxes and expenses shall be paid by the Company, and such Warrant Shares shall be issued in the name of the Holder or in such name or names as may be directed by the Holder; provided, however, that, in the event that Warrant Shares are to be issued in a name other than the name of the Holder, this Warrant when surrendered for exercise shall be accompanied by the Assignment Form attached hereto as Exhibit B duly executed by the Holder and the Company may require, as a condition thereto, the payment of a sum sufficient to reimburse it for any transfer tax incidental thereto. Subject to the foregoing, the Holder shall be responsible for all other tax liability that may arise as a result of holding or transferring this Warrant or receiving Warrant Shares upon exercise hereof, including any United States withholding taxes imposed on any dividends or deemed dividends, and the Company shall be entitled to withhold such tax liability from Shares, sales proceeds subsequently paid or credited, or other amounts payable or distributable to the relevant Holder as required by applicable law. The Company will not close its stockholder books or records in any matter that prevents the timely exercise of this Warrant, pursuant to the terms hereof. The Company’s obligations to issue and deliver Warrant Shares in accordance with the terms and subject to the conditions hereof are absolute and unconditional, irrespective of any action or inaction by the Holder to enforce the same, any waiver or consent with respect to any provision hereof, the recovery of any judgment against any Person or any action to enforce the same, or any setoff, counterclaim, recoupment, limitation or termination; provided, however, that the Company shall not be required to deliver Warrant Shares with respect to an exercise prior to the Holder’s delivery of the Aggregate Exercise Price (or notice of a Cashless Exercise) with respect to such exercise. The Holder and any assignee, by acceptance of this Warrant, acknowledge and agree that, by reason of the provisions of this paragraph, following the purchase of a portion of the Warrant Shares hereunder, the number of Warrant Shares available for purchase hereunder at any given time may be less than the amount stated on the face hereof. “Standard Settlement Period” means the standard settlement period, expressed in a number of Trading Days, for the Company’s primary trading market or quotation system with respect to the Shares that is in effect on the date of receipt of an applicable Exercise Notice. “Trading Day” means any day on which the Shares are traded on the Trading Market, or, if the Trading Market is not the principal trading market for the Shares, then on the principal securities exchange or securities market on which the Shares are then traded.

(g)Company’s Failure to Timely Deliver Securities. If either (I) the Company shall fail for any reason or for no reason to issue or credit, as the case may be, to the Holder on or prior to the applicable Share Delivery Date, if (x) the Transfer Agent is not participating in the DTC Fast Automated Securities Transfer Program, a certificate or evidence of a book-entry credit for the number of Warrant Shares to which the Holder is entitled and register such Shares on the Company’s share register or (y) the Transfer Agent is participating in the DTC Fast Automated Securities Transfer Program, to credit the Holder’s balance account with DTC, for such number of Warrant Shares to which the Holder is entitled upon the Holder’s exercise of this Warrant or (II) a registration statement covering the issuance or resale of the Warrant Shares that are the subject of the Exercise Notice (the “Exercise Notice Warrant Shares”) is not available for the issuance or resale, as applicable, of such Exercise Notice Warrant Shares and (x) the Company fails to promptly, but in no event later than one (1) Business Day after such registration statement becomes unavailable, to so notify the Holder and (y) the Company is unable to deliver the Exercise Notice Warrant Shares electronically without any restrictive legend by crediting such aggregate number of Exercise Notice Warrant Shares to the Holder’s or its designee’s balance account with DTC through its Deposit / Withdrawal At Custodian system (the event described in the immediately foregoing clause (II) is hereinafter referred as a “Notice Failure” and together with the event described in clause (I) above, an “Exercise Failure”), then, in addition to all other remedies available to the Holder, if on or prior to the applicable Share Delivery Date either (I) if the Transfer Agent is not participating in the DTC Fast Automated

Securities Transfer Program, the Company shall fail to issue and deliver a certificate or evidence of a book-entry credit to the Holder and register such Shares on the Company’s share register or, if the Transfer Agent is participating in the DTC Fast Automated Securities Transfer Program, credit the Holder’s balance account with DTC for the number of Shares to which the Holder is entitled upon the Holder’s exercise hereunder or pursuant to the Company’s obligation pursuant to clause (ii) below or (II) if a Notice Failure occurs, and, in each case, if after such date the Holder is required by its broker to purchase (in an open market transaction or otherwise) or the Holder’s brokerage firm otherwise purchases, Shares to deliver in satisfaction of a sale by the Holder of the Warrant Shares which the Holder anticipated receiving upon such exercise (a “Buy-In”), then the Company shall, within five (5) Trading Days after the Holder’s request, (A) pay in cash to the Holder the amount, if any, by which (x) the Holder’s total purchase price (including reasonable and customary brokerage commissions, if any) for the Shares so purchased exceeds (y) the amount obtained by multiplying (1) the number of Warrant Shares that the Company was required to deliver to the Holder in connection with the exercise at issue times and (2) the price at which the sell order giving rise to such purchase obligation was executed, and (B) at the option of the Holder, either reinstate the portion of the Warrant and equivalent number of Warrant Shares for which such exercise was not honored (in which case such exercise shall be deemed rescinded) or deliver to the Holder the number of Shares that would have been issued had the Company timely complied with its exercise and delivery obligations hereunder. For example, if the Holder purchases Shares having a total purchase price of $11,000 to cover a Buy-In with respect to an attempted exercise of Shares with an aggregate sale price giving rise to such purchase obligation of $10,000, under clause (A) of the immediately preceding sentence the Company shall be required to pay the Holder $1,000. The Holder shall provide the Company written notice indicating the amounts payable to the Holder in respect of the Buy-In and, upon request of the Company, evidence of the amount of such loss. Nothing herein shall limit a Holder’s right to pursue any other remedies available to it hereunder, at law or in equity including, without limitation, a decree of specific performance and/or injunctive relief with respect to the Company’s failure to timely deliver Shares upon exercise of the Warrant as required pursuant to the terms hereof. The Company’s current transfer agent participates in the DTC Fast Automated Securities Transfer Program (“FAST”). In the event that the Company changes transfer agents while this Warrant is outstanding, the Company shall select a transfer agent that participates in FAST. While this Warrant is outstanding, the Company shall cause its transfer agent to participate in FAST with respect to this Warrant. In addition to the foregoing rights, (i) if the Company fails to deliver the applicable number of Warrant Shares upon an exercise pursuant to Section 2 by the applicable Share Delivery Date, then the Holder shall have the right to rescind such exercise in whole or in part and retain and/or have the Company return, as the case may be, any portion of this Warrant that has not been exercised pursuant to such Exercise Notice; provided that the rescission of an exercise shall not affect the Company’s obligation to make any payments that have accrued prior to the date of such notice pursuant to this Section 2(f) or otherwise, and (ii) if a registration statement the issuance or resale of the Warrant Shares that are subject to an Exercise Notice is not available for the issuance or resale, as applicable, of such Exercise Notice Warrant Shares and the Holder has submitted an Exercise Notice prior to receiving notice of the non-availability of such registration statement and the Company has not already delivered the Warrant Shares underlying such Exercise Notice electronically without any restrictive legend by crediting such aggregate number of Warrant Shares to which the Holder is entitled pursuant to such exercise to the Holder’s or its designee’s balance account with DTC through its Deposit / Withdrawal At Custodian system, the Holder shall have the option, by delivery of notice to the Company, to (x) rescind such Exercise Notice in whole or in part and retain or have returned, as the case may be, any portion of this Warrant that has not been exercised pursuant to such Exercise Notice; provided that the rescission of an Exercise Notice shall not affect the Company’s obligation to make any payments that have accrued prior to the date of such notice pursuant to this Section 2(f) or otherwise, and/or (y) switch some or all of such Exercise Notice from a cash exercise to a Cashless Exercise.

3.Replacement of the Warrant. Subject to the receipt of evidence reasonably satisfactory to the Company of the loss, theft, destruction or mutilation of this Warrant and, in the case of loss, theft or destruction, on delivery of an indemnity agreement reasonably satisfactory in form and substance to the Company or, in the case of mutilation, on surrender and cancellation of this Warrant, the Company at the expense of the Holder shall execute and deliver, in lieu of this Warrant, a new warrant of like tenor and amount.

4.Transfer of the Warrant.

(a)Warrant Register. The Company shall maintain a register (the “Warrant Register”) containing the name and address of the Holder or Holders. Until this Warrant is transferred on the Warrant Register in accordance herewith, the Company may treat the Holder as shown on the Warrant Register as the absolute owner of this Warrant for all purposes, notwithstanding any notice to the contrary. Any Holder of this Warrant (or of any portion of this Warrant) may change its address as shown on the Warrant Register by written notice to the Company requesting a change.

(b)Warrant Agent. The Company may appoint an agent for the purpose of maintaining the Warrant Register referred to in Section 4(a), issuing the Shares or other securities then issuable upon the exercise of the rights under this Warrant, exchanging this Warrant, replacing this Warrant or conducting related activities.

(c)Transferability of the Warrant. Subject to the provisions of this Warrant with respect to compliance with the Securities Act of 1933, as amended (the “Securities Act”) and limitations on assignments and transfers, including without limitation compliance with the restrictions on transfer set forth in Section 5, title to this Warrant may be transferred by endorsement (by the transferor and the transferee executing the assignment form attached as Exhibit B (the “Assignment Form”)) and delivery in the same manner as a negotiable instrument transferable by endorsement and delivery.

(d)Exchange of the Warrant upon a Transfer. On surrender of this Warrant (and a properly endorsed Assignment Form) for exchange, subject to the provisions of this Warrant with respect to compliance with the Securities Act and limitations on assignments and transfers, the Company shall issue to or on the order of the Holder a new warrant or warrants of like tenor, in the name of the Holder or as the Holder (on payment by the Holder of any applicable transfer taxes) may direct, for the number of shares issuable upon exercise hereof, and the Company shall register any such transfer upon the Warrant Register. This Warrant (and the securities issuable upon exercise of the rights under this Warrant) must be surrendered to the Company or its warrant or transfer agent, as applicable, as a condition precedent to the sale, pledge, hypothecation or other transfer of any interest in any of the securities represented hereby.

(e)Taxes. In no event shall the Company be required to pay any tax which may be payable in respect of any transfer involved in the issue and delivery of any certificate, or a book entry, in a name other than that of the Holder, and the Company shall not be required to issue or deliver any such certificate, or make such book entry, unless and until the person or persons requesting the issue or entry thereof shall have paid to the Company the amount of such tax or shall have established to the satisfaction of the Company that such tax has been paid or is not payable.

5.Restrictions on Transfer of the Warrant and Shares; Compliance with Securities Laws. By acceptance of this Warrant, the Holder agrees to comply with the following:

(a)Restrictions on Transfers. Subject to Section 5(b), this Warrant may not be transferred or assigned in whole or in part without the Company’s prior written consent (which shall not be unreasonably withheld), and any attempt by Holder to transfer or assign any rights, duties or obligations that arise under this Warrant without such permission shall be void. Any transfer of this Warrant or the Shares (the “Securities”) must be in compliance with all applicable federal and state securities laws. The Holder agrees not to make any sale, assignment, transfer, pledge or other disposition of all or any portion of the Securities, or any beneficial interest therein, unless and until the transferee thereof has agreed in writing for the benefit of the Company to take and hold such Securities subject to, and to be bound by, the terms and conditions set forth in this Warrant to the same extent as if the transferee were the original Holder hereunder, and

(1)there is then in effect a registration statement under the Securities Act covering such proposed disposition and such disposition is made in accordance with such registration statement, or

(2)(A) such Holder shall have given prior written notice to the Company of such Holder’s intention to make such disposition and shall have furnished the Company with a detailed description of the manner and circumstances of the proposed disposition, (B) the transferee shall have confirmed to the satisfaction of the Company in writing, substantially in the form of Exhibit A-1, that the Securities are being acquired (i) solely for the transferee’s own account and not as a nominee for any other party, (ii) for investment and (iii) not with a view toward distribution or resale, and shall have confirmed such other matters related thereto as may be reasonably requested by the Company, and (C) if requested by the Company, such Holder shall have furnished the Company, at the Holder’s expense, with an opinion of counsel, reasonably satisfactory to the Company, to the effect that such disposition will not require registration of such Securities under the Securities Act, whereupon such Holder shall be entitled to transfer such Securities in accordance with the terms of the notice delivered by the Holder to the Company.

(b)Permitted Transfers. Permitted transfers with respect to Section 5(a) include (i) a transfer not involving a change in beneficial ownership, or (ii) transactions involving the distribution without consideration of Securities by any Holder to (x) a parent, subsidiary or other affiliate of a Holder that is a corporation, (y) any of the Holder’s partners, members or other equity owners, or retired partners or members, or to the estate of any of its partners, members or other equity owners or retired partners or members, or (z) a venture capital fund that is controlled by or under common control with one or more general partners or managing members of, or shares the same management company with, the Holder; provided, in each case, that the Holder shall give written notice to the Company of the Holder’s intention to effect such disposition and shall have furnished the Company with a detailed description of the manner and circumstances of the proposed disposition.

(c)Investment Representation Statement. Unless the rights under this Warrant are exercised pursuant to an effective registration statement under the Securities Act that includes the Shares with respect to which the Warrant was exercised, it shall be a condition to any exercise of the rights under this Warrant that the Holder shall have confirmed to the satisfaction of the Company in writing, substantially in the form of Exhibit A-1, that the Shares so purchased are being acquired solely for the Holder’s own account and not as a nominee for any other party, for investment and not with a view toward distribution or resale and that the Holder shall have confirmed such other matters related thereto as may be reasonably requested by the Company.

(d)Securities Law Legend. Each certificate, instrument or book entry representing the Securities shall (unless otherwise permitted by the provisions of this Warrant) be notated with a legend substantially similar to the following (in addition to any legend required by state securities laws):

THE SECURITIES REPRESENTED HEREBY HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE “ACT”), OR UNDER THE SECURITIES LAWS OF CERTAIN STATES.

THESE SECURITIES MAY NOT BE OFFERED, SOLD OR OTHERWISE TRANSFERRED, PLEDGED OR HYPOTHECATED EXCEPT AS PERMITTED UNDER THE ACT AND APPLICABLE STATE SECURITIES LAWS IN ACCORDANCE WITH APPLICABLE REGISTRATION REQUIREMENTS OR AN EXEMPTION THEREFROM. THE ISSUER OF THESE SECURITIES MAY REQUIRE AN OPINION OF COUNSEL REASONABLY SATISFACTORY TO THE ISSUER THAT SUCH OFFER, SALE OR TRANSFER, PLEDGE OR HYPOTHECATION OTHERWISE COMPLIES WITH THE ACT AND ANY APPLICABLE STATE SECURITIES LAWS. THIS CERTIFICATE MUST BE SURRENDERED TO THE COMPANY OR ITS TRANSFER AGENT AS A CONDITION PRECEDENT TO THE SALE, TRANSFER, PLEDGE OR HYPOTHECATION OF ANY INTEREST IN ANY OF THE SECURITIES REPRESENTED HEREBY.

(e)Instructions Regarding Transfer Restrictions. The Holder consents to the Company making a notation on its records and giving instructions to any transfer agent in order to implement the restrictions on transfer established in this Section 5.

(f)Removal of Legend. The legend referring to federal and state securities laws identified in Section 5(d) notated on any certificate evidencing or book entry representing the Securities and the stock transfer instructions and record notations with respect to such securities shall be removed, and the Company shall issue a certificate without such legend to the holder of such securities (to the extent the securities are certificated), if (i) such securities are registered under the Securities Act, or (ii) such securities are eligible for resales pursuant to Rule 144 under the Securities Act, in which case counsel to the Company shall provide with an opinion to the Company, at the Company’s expense, to the effect that a sale or transfer of such securities may be made without registration, qualification or legend.

(g)No Transfers to Bad Actors; Notice of Bad Actor Status. The Holder agrees not to sell, assign, transfer, pledge or otherwise dispose of any securities of the Company, or any beneficial interest therein, to any person (other than the Company) unless and until the proposed transferee confirms to the reasonable satisfaction of the Company that neither the proposed transferee nor any of its directors, executive officers, other officers that may serve as a director or officer of any company in which it invests, general partners or managing members nor any person that would be deemed a beneficial owner of those securities (in accordance with Rule 506(d) of the Securities Act) is subject to any of the “bad actor” disqualifications described in Rule 506(d)(1)(i) through (viii) under the Securities Act, except as set forth in Rule 506(d)(2)(ii) or (iii) or (d)(3) under the Securities Act and disclosed, reasonably in advance of the transfer, in writing in reasonable detail to the Company. The Holder will promptly notify the Company in writing if the Holder or, to the Holder’s knowledge, any person specified in Rule 506(d)(1) under the Securities Act becomes subject to any of the “bad actor” disqualifications described in Rule 506(d)(1)(i) through (viii) under the Securities Act.

6.Adjustments. Subject to the expiration of this Warrant pursuant to Section 7, the number and kind of shares purchasable hereunder and the Exercise Price therefor are subject to adjustment from time to time, as follows:

(a)Merger or Reorganization. If at any time there shall be any reorganization, recapitalization, merger or consolidation (a “Reorganization”) involving the Company (other than as otherwise provided for herein or as would cause the expiration of this Warrant under Section 7) in which shares of the Company’s stock are converted into or exchanged for securities, cash or other property, then, as a part of such Reorganization, lawful provision shall be made so that the Holder shall thereafter be entitled to receive upon exercise of this Warrant, the kind and amount of securities, cash or other property of the successor corporation resulting from such Reorganization, equivalent in value to that which a holder of the Shares deliverable upon exercise of this Warrant would have been entitled in such Reorganization if the right to purchase the Shares hereunder had been exercised immediately prior to such Reorganization. In any such case, appropriate adjustment (as determined in good faith by the Board of Directors of the successor corporation) shall be made in the application of the provisions of this Warrant with respect to the rights and interests of the Holder after such Reorganization to the end that the provisions of this Warrant shall be applicable after the event, as near as reasonably may be, in relation to any shares or other securities deliverable after that event upon the exercise of this Warrant.

(b)Reclassification of Shares. If the securities issuable upon exercise of this Warrant are changed into the same or a different number of securities of any other class or classes by reclassification, capital reorganization or otherwise (other than as otherwise provided for herein) (a “Reclassification”), then, in any such event, in lieu of the number of Shares which the Holder would otherwise have been entitled to receive, the Holder shall have the right thereafter to exercise this Warrant for a number of shares of such other class or classes of stock that a holder of the number of securities deliverable upon exercise of this Warrant immediately before that change would have been entitled to receive in such Reclassification, all subject to further adjustment as provided herein with respect to such other shares.

(c)Subdivisions and Combinations. In the event that the outstanding shares of common stock are subdivided (by stock split, by payment of a stock dividend or otherwise) into a greater number of shares of such securities, the number of Shares issuable upon exercise of the rights under this Warrant immediately prior to such subdivision shall, concurrently with the effectiveness of such subdivision, be proportionately increased, and the Exercise Price shall be proportionately decreased, and in the event that the outstanding shares of common stock are combined (by reclassification or otherwise) into a lesser number of shares of such securities, the number of Shares issuable upon exercise of the rights under this Warrant immediately prior to such combination shall, concurrently with the effectiveness of such combination, be proportionately decreased, and the Exercise Price shall be proportionately increased.

(d)Notice of Adjustments. Upon any adjustment in accordance with this Section 6(d), the Company shall give notice thereof to the Holder, which notice shall state the event giving rise to the adjustment, the Exercise Price as adjusted and the number of securities or other property purchasable upon the exercise of the rights under this Warrant, setting forth in reasonable detail the method of calculation of each. The Company shall, upon the written request of any Holder, furnish or cause to be furnished to such Holder a certificate setting forth (i) such adjustments, (ii) the Exercise Price at the time in effect and (iii) the number of securities and the amount, if any, of other property that at the time would be received upon exercise of this Warrant.

7.Expiration of the Warrant. This Warrant shall expire and shall no longer be exercisable as of the earlier of:

(a) 5:00 p.m., Pacific time, on the date that is the fifth anniversary of the date upon which this Warrant is first exercisable pursuant to Section 1(c); and

(b)(i) the acquisition of the Company by another entity by means of any transaction or series of related transactions to which the Company is a party (including, without limitation, any stock acquisition, reorganization, merger or consolidation, but excluding any sale of stock for capital raising purposes and any transaction effected primarily for purposes of changing the Company’s jurisdiction of incorporation) other than a transaction or series of related transactions in which the holders of the voting securities of the Company outstanding immediately prior to such transaction or series of related transactions retain, immediately after such transaction or series of transactions, as a result of shares in the Company held by such holders prior to such transaction or series of transactions, at least a majority of the total voting power represented by the outstanding voting securities of the Company or such other surviving or resulting entity (or if the Company or such other surviving or resulting entity is a wholly-owned subsidiary immediately following such acquisition, its parent), or (ii) a sale, lease or other disposition of all or substantially all of the assets of the Company and its subsidiaries taken as a whole by means of any transaction or series of related transactions, except where such sale, lease or other disposition is to a wholly-owned subsidiary of the Company.

8.Notification of Certain Events. Prior to the expiration of this Warrant pursuant to Section 7(b), in the event that the Company shall authorize:

(a)the issuance of any dividend or other distribution on the capital stock of the Company (other than (i) dividends or distributions otherwise provided for in Section 6, (ii) repurchases of common stock issued to or held by employees, officers, directors or consultants of the Company or its subsidiaries; or (iii) repurchases of capital stock of the Company in connection with the settlement of disputes with any stockholder), whether in cash, property, stock or other securities;

(b)the voluntary liquidation, dissolution or winding up of the Company; or

(c)any transaction resulting in the expiration of this Warrant pursuant to Section 7(b), the Company shall send to the Holder of this Warrant at least ten (10) days prior written notice of the date on which a record shall be taken for any such dividend or distribution specified in clause (a) or the expected effective date of any such other event specified in clause (b) or (c), as applicable.

9.No Rights as a Stockholder. Nothing contained herein shall entitle the Holder to any rights as a stockholder of the Company or to be deemed the holder of any securities that may at any time be issuable on the exercise of the rights hereunder for any purpose nor shall anything contained herein be construed to confer upon the Holder, as such, any right to vote for the election of directors or upon any matter submitted to stockholders at any meeting thereof, or to give or withhold consent to any corporate action (whether upon any recapitalization, issuance of stock, reclassification of stock, change of par value or change of stock to no par value, consolidation, merger, conveyance or otherwise) or to receive notice of meetings, or to receive dividends or subscription rights or any other rights of a stockholder of the Company until the rights under the Warrant shall have been exercised and the Shares purchasable upon exercise of the rights hereunder shall have become deliverable as provided herein.

10.Representations and Warranties of the Holder. By acceptance of this Warrant, the Holder represents and warrants to the Company as follows:

(a)No Registration. The Holder understands that the Securities have not been, and will not be, registered under the Securities Act by reason of a specific exemption from the registration provisions of the Securities Act, the availability of which depends upon, among other things, the bona fide nature of the investment intent and the accuracy of the Holder’s representations as expressed herein or otherwise made pursuant hereto.

(b)Investment Intent. The Holder is acquiring the Securities for investment for its own account, not as a nominee or agent, and not with a view to, or for resale in connection with, any distribution thereof. The Holder has no present intention of selling, granting any participation in, or otherwise distributing the Securities, nor does it have any contract, undertaking, agreement or arrangement for the same.

(c)Investment Experience. The Holder has substantial experience in evaluating and investing in private placement transactions of securities in companies similar to the Company, and has such knowledge and experience in financial or business matters so that it is capable of evaluating the merits and risks of its investment in the Company and protecting its own interests.

(d)Speculative Nature of Investment. The Holder understands and acknowledges that its investment in the Company is highly speculative and involves substantial risks. The Holder can bear the economic risk of its investment and is able, without impairing its financial condition, to hold the Securities for an indefinite period of time and to suffer a complete loss of its investment.

(e)Access to Data. The Holder has had an opportunity to ask questions of officers of the Company, which questions were answered to its satisfaction. The Holder believes that it has received all the information that it considers necessary or appropriate for deciding whether to acquire the Securities. The Holder understands that any such discussions, as well as any information issued by the Company, were intended to describe certain aspects of the Company’s business and prospects, but were not necessarily a thorough or exhaustive description. The Holder acknowledges that any business plans prepared by the Company have been, and continue to be, subject to change and that any projections included in such business plans or otherwise are necessarily speculative in nature, and it can be expected that some or all of the assumptions underlying the projections will not materialize or will vary significantly from actual results.

(f)Accredited Investor. The Holder is an “accredited investor” within the meaning of Regulation D, Rule 501(a), promulgated by the Securities and Exchange Commission and agrees to submit to the Company such further assurances of such status as may be reasonably requested by the Company. The Holder has furnished or made available any and all information requested by the Company or otherwise necessary to satisfy any applicable verification requirements as to “accredited investor” status. Any such information is true, correct, timely and complete.

(g)Residency. The residency of the Holder (or, in the case of a partnership or corporation, such entity’s principal place of business) is correctly set forth on the signature page hereto.

(h)Restrictions on Resales. The Holder acknowledges that the Securities must be held indefinitely unless subsequently registered under the Securities Act or an exemption from such registration is available. The Holder is aware of the provisions of Rule 144 promulgated under the Securities Act, which permit resale of shares purchased in a private placement subject to the satisfaction of certain conditions, which may include, among other things, the availability of certain current public information about the Company; the resale occurring not less than a specified period after a party has purchased and paid for the security to be sold; the number of shares being sold during any three-month period not exceeding specified limitations; the sale being effected through a “broker’s transaction,” a transaction directly with a “market maker” or a “riskless principal transaction” (as those terms are defined in the Securities Act or the Securities Exchange Act of 1934, as amended, and the rules and regulations promulgated thereunder); and the filing of a Form 144 notice, if applicable. The Holder acknowledges and understands that the Company may not be satisfying the current public information requirement of Rule 144 at the time the Holder wishes to sell the Securities and that, in such event, the Holder may be precluded from selling the Securities under Rule 144 even if the other applicable requirements of Rule 144 have been satisfied. The Holder acknowledges that, in the event the applicable requirements of Rule 144 are not met, registration under the Securities Act or an exemption from registration will be required for any disposition of the Securities. The Holder understands that, although Rule 144 is not exclusive, the Securities and Exchange Commission has expressed its opinion that persons proposing to sell restricted securities received in a private offering other than in a registered offering or pursuant to Rule 144 will have a substantial burden of proof in establishing that an exemption from registration is available for such offers or sales and that such persons and the brokers who participate in the transactions do so at their own risk.

(i)Brokers and Finders. The Holder has not engaged any brokers, finders or agents in connection with the Securities, and the Company has not incurred nor will incur, directly or indirectly, as a result of any action taken by the Holder, any liability for brokerage or finders’ fees or agents’ commissions or any similar charges in connection with the Securities.

(j)Legal Counsel. The Holder has had the opportunity to review this Warrant, the exhibits and schedules attached hereto and the transactions contemplated by this Warrant with its own legal counsel. The Holder is not relying on any statements or representations of the Company or its agents for legal advice with respect to this investment or the transactions contemplated by this Warrant.

(k)Tax Advisors. The Holder has reviewed with its own tax advisors the U.S. federal, state and local and non-U.S. tax consequences of this investment and the transactions contemplated by this Warrant. With respect to such matters, the Holder relies solely on any such advisors and not on any statements or representations of the Company or any of its agents, written or oral. The Holder understands that it (and not the Company) shall be responsible for its own tax liability that may arise as a result of this investment and the transactions contemplated by this Warrant.

(l)No “Bad Actor” Disqualification. Neither (i) the Holder, (ii) any of its directors, executive officers, other officers that may serve as a director or officer of any company in which it invests, general partners or managing members, nor (iii) any beneficial owner of any of the Company’s voting equity securities (in accordance with Rule 506(d) of the Securities Act) held by the Holder is subject to any of the “bad actor” disqualifications described in Rule 506(d)(1)(i) through (viii) under the Securities Act, except as set forth in Rule 506(d)(2)(ii) or (iii) or (d)(3) under the Securities Act and disclosed, reasonably in advance of the acceptance of this Warrant, in writing in reasonable detail to the Company.

11.[Reserved]

12.Registration Rights. The Company shall, as promptly as practicable, but in any event later than November 14, 2025, prepare and file a registration statement with the Commission pursuant to Rule 415 under the Securities Act on Form S-3 under the Securities Act (or in the event that the Company is ineligible to use such form, such other form as the Company is eligible to use under the Securities Act provided that such other form shall be converted into a Form S-3 promptly after Form S-3 becomes available to the Company) covering resales by the Holder as a selling stockholder of the Warrant Shares (the “Registration Statement”). The Company shall use its commercially reasonable efforts to cause the Registration Statement to be declared effective as soon as practicable thereafter. The Company, in its sole discretion, may elect to include for offer and sale securities, including primary offerings by the Company, in addition to the Warrant Shares in the Registration Statement. Promptly following the effective date of the Registration Statement, the Company shall file with the Commission in accordance with Rule 424(b) under the Securities Act the final prospectus to be used in connection with sales pursuant to the Registration Statement unless such a prospectus is not technically required by such rule. In addition, unless all of the Warrant Shares are included in an effective registration statement (including the Registration Statement) with a current prospectus, the Holder shall have the right, commencing on the date that this Warrant becomes exercisable to include the remaining Warrant Shares as part of any other registration of securities filed by the Company (other than in connection with a transaction contemplated by Rule 145 promulgated under the Securities Act or pursuant to Form S-8 or any equivalent form); provided, however, that if, solely in connection with any underwritten public offering, the managing underwriter(s) thereof shall, in its reasonable discretion, impose a limitation on the number of shares of Common Stock of Warrant Shares which may be included in the registration statement because, in such underwriter(s)’ judgment, marketing or other factors dictate such limitation is necessary to facilitate public distribution, then the Company shall be obligated to include in such registration statement only such limited portion of the Warrant Shares with respect to which the Holder requested inclusion hereunder as the underwriter shall reasonably permit; provided further that no such piggy-back rights shall exist for so long as the Warrant Shares (which term shall include those paid as consideration pursuant to the cashless exercise provisions of this Warrant) may be sold pursuant to Rule 144 of the Securities Act without volume or manner of sale restriction; and further provided that such piggy-back rights shall be subordinate to any similar rights to which the Company is subject as of the date of this Warrant. Any exclusion of Warrant Shares shall be made pro rata among the Holders seeking to include Warrant Shares in proportion to the number of Warrant Shares sought to be included by such Holders. In the event of such a proposed registration, the Company shall furnish the then Holders of outstanding Warrant Shares with not less than five (5) days written notice prior to the proposed date of filing of such registration statement. Such notice to the Holders shall continue to be given for each registration statement filed by the Company until such time as all of the Warrant Shares have been sold by the Holder, unless, for the avoidance of doubt, all of the Warrant Shares are already included in an effective registration statement with a current prospectus. The holders of the Warrant Shares shall exercise the “piggy-back” rights provided for herein by giving written notice, within two (2) days of the receipt of the Company’s notice of its intention to file a registration statement. Except as otherwise provided in this Warrant, there shall be no limit on the number of times the Holder may request registration under this Section 12. Notwithstanding any provision to the contrary herein, the provisions of this Section 12 shall survive the termination of this Warrant until the earliest to occur of (A) a registration statement with respect to the sale of the Warrant Shares shall have become effective under the Securities Act and the Warrant Shares shall have been sold, transferred, disposed of or exchanged in accordance with such registration statement by the Holder; (B) the Warrant Shares shall have ceased to be outstanding; (C) the Warrant Shares may be sold without registration pursuant to Rule 144 or any successor rule promulgated under the Securities Act (but with no volume or other restrictions or limitations as to manner or timing of sale); and (D) the Warrant Shares have been sold to, or through, a broker, dealer or underwriter in a public distribution or other public securities transaction.

13.Miscellaneous. The provisions of Section 8 (Choice of Law; Venue; Waiver of Jury Trial) of the Note shall apply to this Warrant, mutatis mutandis.

The Company and the Holder sign this Warrant as of the date stated on the first page.

By: /s/ Kate Suhadolnik    

Name: Kate Suhadolnik

Title: Interim Chief Financial Officer

Address:

26440 SW Parkway Ave., Bldg. 83
Wilsonville, OR, 97070
Attention: Interim Chief Financial Officer
Email: [***]

    By: /s/ Matt Beckman    

    Name: Matt Beckman

    Title: Member

1012 Springfield Avenue 
Mountainside, NJ 07092

Email address: [***]

TO:    ESS Tech, Inc. (the “Company”)

(a)Exercise. The undersigned elects to purchase the following pursuant to the terms of the attached warrant:

Number of shares:        

Type of security:        

(b)Method of Exercise. The undersigned elects to exercise the attached warrant pursuant to:

    A cash payment or cancellation of indebtedness, and tenders herewith payment of the purchase price for such shares in full, together with all applicable transfer taxes, if any.

    The net issue exercise provisions of Section 2(b) of the attached warrant.

(c)Stock. Please make a book entry and, if the shares are certificated, issue a certificate or certificates representing the shares in the name of:

    Other—Name:        

Address:        

    

(d)Unexercised Portion of the Warrant. Please issue a new warrant for the unexercised portion of the attached warrant in the name of:

    Other—Name:        

Address:        

    

    Not applicable

(e)Investment Intent. The undersigned represents and warrants that the aforesaid shares are being acquired for investment for its own account, not as a nominee or agent, and not with a view to, or for resale in connection with, the distribution thereof, and that the undersigned has no present intention of selling, granting any participation in, or otherwise distributing the shares, nor does it have any contract, undertaking, agreement or arrangement for the same, and all representations and warranties of the undersigned set forth in Section 10 of the attached warrant are true and correct as of the date hereof.

(f)Investment Representation Statement. The undersigned has executed, and delivers herewith, an Investment Representation Statement in a form substantially similar to the form attached to the warrant as Exhibit A-1.

(g)Consent to Receipt of Electronic Notice. Subject to the limitations set forth in Delaware General Corporation Law §232(e), the undersigned consents to the delivery of any notice to stockholders given by the Company under the Delaware General Corporation Law or the Company’s certificate of incorporation or bylaws by (i) facsimile telecommunication to the

facsimile number provided below (or to any other facsimile number for the undersigned in the Company’s records), (ii) electronic mail to the electronic mail address provided below (or to any other electronic mail address for the undersigned in the Company’s records), (iii) posting on an electronic network together with separate notice to the undersigned of such specific posting or (iv) any other form of electronic transmission (as defined in the Delaware General Corporation Law) directed to the undersigned. This consent may be revoked by the undersigned by written notice to the Company and may be deemed revoked in the circumstances specified in Delaware General Corporation Law §232.

        

(Print name of the warrant holder)

        

(Signature)

        

        

(Date)

        

(Email address)

INVESTOR:                                        

SECURITIES:    THE WARRANT ISSUED ON OCTOBER 14, 2025 (THE “WARRANT”) AND THE SECURITIES ISSUED OR ISSUABLE UPON EXERCISE THEREOF

DATE:                                

In connection with the purchase or acquisition of the above-listed Securities, the undersigned Investor represents and warrants to, and agrees with, the Company as follows:

1.No Registration. The Investor understands that the Securities have not been, and will not be, registered under the Securities Act of 1933, as amended (the “Securities Act”), by reason of a specific exemption from the registration provisions of the Securities Act, the availability of which depends upon, among other things, the bona fide nature of the investment intent and the accuracy of the Investor’s representations as expressed herein or otherwise made pursuant hereto.

2.Investment Intent. The Investor is acquiring the Securities for investment for its own account, not as a nominee or agent, and not with a view to, or for resale in connection with, any distribution thereof. The Investor has no present intention of selling, granting any participation in, or otherwise distributing the Securities, nor does it have any contract, undertaking, agreement or arrangement for the same.

3.Investment Experience. The Investor has substantial experience in evaluating and investing in private placement transactions of securities in companies similar to the Company, and has such knowledge and experience in financial or business matters so that it is capable of evaluating the merits and risks of its investment in the Company and protecting its own interests.

4.Speculative Nature of Investment. The Investor understands and acknowledges that its investment in the Company is highly speculative and involves substantial risks. The Investor can bear the economic risk of its investment and is able, without impairing its financial condition, to hold the Securities for an indefinite period of time and to suffer a complete loss of its investment.

5.Access to Data. The Investor has had an opportunity to ask questions of officers of the Company, which questions were answered to its satisfaction. The Investor believes that it has received all the information that it considers necessary or appropriate for deciding whether to acquire the Securities. The Investor understands that any such discussions, as well as any information issued by the Company, were intended to describe certain aspects of the Company’s business and prospects, but were not necessarily a thorough or exhaustive description. The Investor acknowledges that any business plans prepared by the Company have been, and continue to be, subject to change and that any projections included in such business plans or otherwise are necessarily speculative in nature, and it can be expected that some or all of the assumptions underlying the projections will not materialize or will vary significantly from actual results.

6.Accredited Investor. The Investor is an “accredited investor” within the meaning of Regulation D, Rule 501(a), promulgated by the Securities and Exchange Commission and agrees to submit to the Company such further assurances of such status as may be reasonably requested by the Company. The Investor has furnished or made available any and all information requested by the Company or otherwise necessary to satisfy any applicable verification requirements as to “accredited investor” status. Any such information is true, correct, timely and complete.

7.Residency. The residency of the Investor (or, in the case of a partnership or corporation, such entity’s principal place of business) is correctly set forth on the signature page hereto.

8.Restrictions on Resales. The Investor acknowledges that the Securities must be held indefinitely unless subsequently registered under the Securities Act or an exemption from such registration is available. The Investor is aware of the provisions of Rule 144 promulgated under the Securities Act, which permit resale of shares purchased in a private placement subject to the satisfaction of certain conditions, which may include, among other things, the availability of certain current public information about the Company; the resale occurring not less than a specified period after a party has purchased and paid for the security to be sold; the number of shares being sold during any three-month period not exceeding specified limitations; the sale being effected through a “broker’s transaction,” a transaction directly with a “market maker” or a “riskless principal transaction” (as those terms are defined in the Securities Act or the Securities Exchange Act of 1934, as amended, and the rules and regulations promulgated thereunder); and the filing of a Form 144 notice, if applicable. The Investor acknowledges and understands that the Company may not be satisfying the current public information requirement of Rule 144 at the time the Investor wishes to sell the Securities and that, in such event, the Investor may be precluded from selling the Securities under Rule 144 even if the other applicable requirements of Rule 144 have been satisfied. The Investor understands and acknowledges that, in the event the applicable requirements of Rule 144 are not met, registration under the Securities Act or an exemption from registration will be required for any disposition of the Securities. The Investor understands that, although Rule 144 is not exclusive, the Securities and Exchange Commission has expressed its opinion that persons proposing to sell restricted securities received in a private offering other than in a registered offering or pursuant to Rule 144 will have a substantial burden of proof in establishing that an exemption from registration is available for those offers or sales and that those persons and the brokers who participate in the transactions do so at their own risk.

9.Brokers and Finders. The Investor has not engaged any brokers, finders or agents in connection with the Securities, and the Company has not incurred nor will incur, directly or indirectly, as a result of any action taken by the Investor, any liability for brokerage or finders’ fees or agents’ commissions or any similar charges in connection with the Securities.

10.Legal Counsel. The Investor has had the opportunity to review the Warrant, the exhibits and schedules attached thereto and the transactions contemplated by the Warrant with its own legal counsel. The Investor is not relying on any statements or representations of the Company or its agents for legal advice with respect to this investment or the transactions contemplated by the Warrant.

11.Tax Advisors. The Investor has reviewed with its own tax advisors the U.S. federal, state and local and non-U.S. tax consequences of this investment and the transactions contemplated by the Warrant. With respect to such matters, the Investor relies solely on such advisors and not on any statements or representations of the Company or any of its agents, written or oral. The Investor understands that it (and not the Company) shall be responsible for its own tax liability that may arise as a result of this investment or the transactions contemplated by the Warrant.

12.No “Bad Actor” Disqualification. Neither (i) the Investor, (ii) any of its directors, executive officers, other officers that may serve as a director or officer of any company in which it invests, general partners or managing members, nor (iii) any beneficial owner of any of the Company’s voting equity securities (in accordance with Rule 506(d) of the Securities Act) held by the Investor is subject to any of the “bad actor” disqualifications described in Rule 506(d)(1)(i) through (viii) under the Securities Act, except as set forth in Rule 506(d)(2)(ii) or (iii) or (d)(3) under the Securities Act and disclosed, reasonably in advance of the purchase or acquisition of the Securities, in writing in reasonable detail to the Company.

The Investor is signing this Investment Representation Statement on the date first written above.

        

(Print name of the investor)

        

(Signature)

        

        

(Street address)

        

(City, state and ZIP)

ASSIGNOR:                                            

WARRANT:    THE WARRANT TO PURCHASE SHARES OF COMMON STOCK ISSUED ON OCTOBER 14, 2025 (THE “WARRANT”)

DATE:    _________________________

(h)Assignment. The undersigned registered holder of the Warrant (“Assignor”) assigns and transfers to the assignee named below (“Assignee”) all of the rights of Assignor under the Warrant, with respect to the number of shares set forth below:

Name of Assignee:     

Address of Assignee:        

        

Number of Shares Assigned:     

and does irrevocably constitute and appoint ______________________ as attorney to make such transfer on the books of ESS Tech, Inc., maintained for the purpose, with full power of substitution in the premises.

(i)Obligations of Assignee. Assignee agrees to take and hold the Warrant and any shares of stock to be issued upon exercise of the rights thereunder (the “Securities”) subject to, and to be bound by, the terms and conditions set forth in the Warrant to the same extent as if Assignee were the original holder thereof.

(j)Investment Intent. Assignee represents and warrants that the Securities are being acquired for investment for its own account, not as a nominee or agent, and not with a view to, or for resale in connection with, the distribution thereof, and that Assignee has no present intention of selling, granting any participation in, or otherwise distributing the shares, nor does it have any contract, undertaking, agreement or arrangement for the same, and all representations and warranties set forth in Section 10 of the Warrant are true and correct as to Assignee as of the date hereof.

(k)Investment Representation Statement. Assignee has executed, and delivers herewith, an Investment Representation Statement in a form substantially similar to the form attached to the Warrant as Exhibit A-1.

(l)No “Bad Actor” Disqualification. Neither (i) Assignee, (ii) any of its directors, executive officers, other officers that may serve as a director or officer of any company in which it invests, general partners or managing members, nor (iii) any beneficial owner of any of the Company’s securities held or to be held by Assignee is subject to any of the “bad actor” disqualifications described in Rule 506(d)(1)(i) through (viii) under the Securities Act of 1933, as amended (the “Securities Act”), except as set forth in Rule 506(d)(2)(ii) or (iii) or (d)(3) under the Securities Act and disclosed, reasonably in advance of the transfer of the Securities, in writing in reasonable detail to the Company.

Assignor and Assignee are signing this Assignment Form on the date first set forth above.

THIS HAS NOT BEEN REGISTERED WITH THE SECURITIES AND EXCHANGE COMMISSION OR THE SECURITIES COMMISSION OF ANY STATE. THIS NOTE HAS BEEN SOLD IN RELIANCE UPON AN EXEMPTION FROM REGISTRATION UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE “SECURITIES ACT”), AND, ACCORDINGLY, MAY NOT BE OFFERED OR SOLD EXCEPT PURSUANT TO AN EFFECTIVE REGISTRATION STATEMENT UNDER THE SECURITIES ACT OR PURSUANT TO AN AVAILABLE EXEMPTION FROM, OR IN A TRANSACTION NOT SUBJECT TO, THE REGISTRATION REQUIREMENTS OF THE SECURITIES ACT AND IN ACCORDANCE WITH APPLICABLE STATE SECURITIES LAWS.

ESS Tech, Inc.

FOR VALUE RECEIVED, ESS Tech, Inc., an entity organized under the laws of the State of Delaware (the “Company”), hereby promises to pay to the order of YA II PN, Ltd., a Cayman Islands exempt limited company (“Yorkville”), or its registered assigns (the “Holder”), the amount set out above as the Original Principal Amount or such lesser amount as shall equal the outstanding principal amount hereof (the “Principal”), in each case when due, and to pay interest (“Interest”) on any outstanding Principal at the applicable Interest Rate (as defined below) from the date set out above as the Issuance Date (the “Issuance Date”) until the same becomes due and payable, whether upon the Maturity Date or acceleration, conversion, redemption or otherwise (in each case in accordance with the terms hereof). Certain capitalized terms used herein are defined in Section (14). The Issuance Date is the date of the first issuance of this Promissory Note (as amended, amended and restated, extended, supplemented or otherwise modified in writing from time to time, this “Note”) regardless of the number of transfers and regardless of the number of instruments, which may be issued to evidence such Note. This Note was issued with an 8% original issue discount.

(1)GENERAL TERMS

(a)Funding.

(i)Subject to the satisfaction (or waiver) of the conditions set forth in Section (4)(a) below, on the Issuance Date, the Holder shall pay to the Company an amount equal to $30,000,000, less a discount equal to 8% of the Original Principal Amount, netted from the purchase price due and structured as an original issue discount (the “Original Issue Discount”), in immediately available funds to an account designated by the Company in writing as set forth on a closing statement to be signed on the date hereof, and the Company shall deliver this Note to the Holder with a Principal amount equal to the full Original Principal Amount set forth above, duly executed on behalf of the Company; and the Company shall issue and deliver to the Holder, a Warrant for the number of Warrant Shares set forth opposite the Holder’s name on Schedule II attached hereto. The Company acknowledges and agrees that the Original Issue Discount (i) shall not be funded but shall be deemed to be fully earned upon issuance of the Note, and (ii) shall not reduce the principal amount of the Note.

(ii)Subject to the satisfaction (or waiver) of the conditions set forth in Section (4)(b) below, on the date in which all the conditions in Section (4)(b) below are satisfied (or waived) (such date being the “Second Tranche Date”), the Holder shall pay to the Company an amount equal to $10,000,000, less a discount equal to the Original Issue Discount, in immediately available funds to an account designated by the Company in writing as set forth on a closing statement to be signed on the date of the Second Tranche Date. The Company acknowledges and agrees that the Original Issue Discount (i) shall not be funded but shall be deemed to be fully earned upon the Second Tranche Date, and (ii) shall not reduce the principal amount of the Note. The Second Tranche Date shall not be later December 12, 2025.

(b)Maturity Date. On the Maturity Date, the Company shall pay to the Holder an amount in cash representing all outstanding Principal, accrued and unpaid Interest, and any other amounts outstanding pursuant to the terms of this Note. The “Maturity Date” shall be October 14, 2026, as may be extended at the option of the Holder.

(c)Interest Rate and Payment of Interest. Interest shall accrue on the outstanding Principal balance hereof at an annual rate equal to 3% (“Interest Rate”), which Interest Rate shall increase to an annual rate of 18% upon the occurrence and during the continuance of an Event of Default (for so long as such event remains uncured). Interest shall be calculated based on a 365-day year and the actual number of days elapsed, to the extent permitted by applicable law.

(d)Monthly Payments. Beginning on the one-month anniversary of the Issuance Date and continuing on the same day of each successive calendar month (each, an “Installment Date”) set forth on the repayment schedule attached hereto as Schedule I (the “Repayment Schedule”), the Company shall repay a portion of the outstanding balance of this Note in an amount equal to the Principal amount set forth on the Repayment Schedule as of such repayment date, plus all accrued and unpaid Interest on this Note as of such Installment Date (collectively, the “Installment Amount”). With respect to the payment of any Installment Amount by the Company hereunder, the Company shall, at its own option, repay each Installment Amount either (i) in cash on or before the Installment Date, or (ii) by submitting an Advance Notice (as defined in the SEPA) (an “Advance Repayment”), or a series of Advance Notices, each with an Advance Date (as defined in the SEPA) on or before the applicable Installment Date, or any combination of (i) or (ii) as determined by the Company. In respect of any Installment Amount, or portion thereof, to be repaid by the Company in accordance with (i) of this Section 1(d), the Company shall pay to the Holder such Installment Amount to the Holder by wire transfer of immediately available funds in cash on or before such Installment Date. If the Company elects an Advance Repayment in accordance with (ii) of this Section 1(d), for all or a portion of an Installment Amount, then the Company shall deliver an Advance Notice to the Holder in accordance with the terms and conditions of the SEPA, that will have an Advance Date on or before the applicable Installment Date. Upon the closing of such Advance Notice in accordance with the SEPA, the Holder shall offset the amount due to be paid by the Holder to the Company under the SEPA against an equal amount of the Installment Amount to be paid by the Advance Repayment. If, on the Installment Date any portion of the Installment Amount remains unpaid, the Company shall repay such outstanding payment amount as a cash repayment pursuant to (i) of this Section 1(d). The Repayment Schedule may be modified from time to time upon mutual consent. Unless otherwise agreed by the Holder, any Advance Repayments delivered while this Note is outstanding shall first be used to satisfy any Installment Amount coming due within the next 30 days, and if no amounts are due during such period, the proceeds of the Advance Repayment shall be split, with 80% of the proceeds used to satisfy future Installment Amounts coming due in reverse order of maturity, and the remaining 20% of the proceeds to be paid to the Company. In addition, unless otherwise agreed by the Holder, following the completion of the SEPA, any proceeds from the ATM Program while this Note is outstanding shall first be used to satisfy any Installment Amount coming due within the next 30 days, and if no amounts are due during such period, such proceeds shall be split, with 80% of the proceeds used to satisfy future Installment Amounts coming due in reverse order of maturity, and the remaining 20% of the proceeds to be paid to the Company.

(e)Payment Dates. Whenever any payment or other obligation hereunder shall be due on a day other than a Business Day, such payment shall be made on the next succeeding Business Day.

(f)Prepayment.    The Company may prepay this Note in whole or in part, provided that any such prepayment will be applied first to the payment of expenses due under this Note, second to interest accrued on this Note and third, if the amount of prepayment exceeds the amount of all such expenses and accrued interest, to the payment of Principal of this Note.

(2)REPRESENTATIONS AND WARRANTIES OF THE COMPANY. The Company represents and warrants to, and agrees in favor of, the Holder that:

(a)Organization. The Company and each of its Subsidiaries are entities duly formed, validly existing and in good standing under the laws of the jurisdiction in which they are formed, and have the requisite power and authority to own their properties and to carry on their business as now being conducted. The Company and each of its Subsidiaries is duly qualified to do business and is in good standing in every jurisdiction in which the nature of the business conducted by it makes such qualification necessary, except to the extent that the failure to be so qualified or be in good standing would not have a Material Adverse Effect.

(b)Authorization; Enforcement. The Company has the requisite corporate power and authority to execute and deliver this Note and to perform its obligations under this Note and the other Transaction Documents. This Note has been and the other Transaction Documents to be entered into simultaneously with the Note and to which the Company is a party, each have been duly executed and delivered by the Company, and each constitutes the legal, valid and binding obligations of the Company, enforceable against the Company in accordance with its terms, except as such enforceability may be limited by bankruptcy, insolvency or other laws of general application relating to or affecting the enforcement of creditors’ rights generally and general principles of equity.

(c)No Conflicts. The execution and delivery by the Company of the Transaction Documents, and the performance by the Company of its obligations under the Transaction Documents, including this Note, do not and will not (i) conflict with or result in a breach or violation of any of the terms or provisions of, or constitute a default under, or result in the creation or imposition of any lien, security interest, pledge, mortgage, charge or other encumbrance (collectively, “Liens”) upon any of the property or assets of the Company pursuant to the terms of any indenture, mortgage, deed of trust, loan agreement, lease, license or other agreement or instrument to which the Company is a party or by which the Company is bound or to which any of the property or assets of the Company is subject, (ii) breach or violate the organizational documents of the Company; or (iii) violate any statute or any judgment, order, rule or regulation of any court or governmental agency or body, domestic or foreign, having jurisdiction over the Company or any of its properties; except in the case of each of clauses (i) and (iii), such as would not have or reasonably be expected to result in a Material Adverse Effect.

(d) No “Bad Actor” Disqualification Events. Neither (i) the Company, (ii) any predecessor or affiliated issuer of the Company, (iii) any of its directors, executive officers, or other officers, nor (iv) any beneficial owner of any of the Company’s voting equity securities (in accordance with Rule 506(d) of the Securities Act) is subject to any of the “bad actor” disqualifications described in Rule 506(d)(1)(i) through (viii) under the Securities Act (“Disqualification Events”), except for Disqualification Events covered by Rule 506(d)(2)(ii) or (iii) or (d)(3) under the Securities Act and disclosed reasonably in advance of the issuance of this Note in writing in reasonable detail to the Company.

(e)No Claims. No creditors, vendors, or other third parties shall have any Lien (as defined below) on the proceeds of this Note, other than (i) Liens arising in the ordinary course of business, in each case, as disclosed to and consented to in writing by the Holder, or (ii) liens in connection with the EXIM Loan.

(f)Subsidiaries. The Company does not have any Subsidiaries except Project New Horizon, LLC, a Delaware limited liability company, which is an Immaterial Subsidiary.

(3)EVENTS OF DEFAULT.

(a)An “Event of Default”, wherever used herein, means any one of the following events (whatever the reason and whether it shall be voluntary or involuntary or effected by operation of law or pursuant to any judgment, decree or order of any court, or any order, rule or regulation of any administrative or governmental body) shall have occurred:

(i)the Company’s failure to pay to the Holder any amount of Principal, Interest, or other amounts when and as due under this Note or any other Transaction Document within 5 Trading Days after such payment is due;

(ii)(A) the Company or any Subsidiary of the Company shall commence, or there shall be commenced against the Company or any Subsidiary of the Company any proceeding under any applicable bankruptcy or insolvency laws as now or hereafter in effect or any successor thereto, or the Company or any Subsidiary of the Company commences any other proceeding under any reorganization, arrangement, adjustment of debt, relief of debtors, dissolution, insolvency or liquidation or similar law of any jurisdiction, whether now or hereafter in effect relating to the Company or any Subsidiary of the Company, and any such bankruptcy, insolvency or other proceeding which remains undismissed for a period of forty-five (45) days; (B) the Company or any Subsidiary of the Company is adjudicated insolvent or bankrupt; (C) any order of relief or other order approving any such case or proceeding is entered; or the Company or any Subsidiary of the Company suffers any appointment of any custodian, private or court appointed receiver or the like for it or all or substantially all of its property which continues undischarged or unstayed for a period of forty-five (45) days; (D) the Company or any Subsidiary of the Company makes a general assignment of all or substantially all of its assets for the benefit of creditors; (E) the Company or any Subsidiary of the Company shall fail to pay, or shall state that it is unable to pay, or shall be unable to pay, its debts generally as they become due; (F) the Company or any Subsidiary of the Company shall call a meeting of its creditors with a view to arranging a composition, adjustment or restructuring of its debts; (G) the Company or any Subsidiary of the Company shall by any act or failure to act expressly indicate its consent to, approval of or acquiescence in any of the foregoing; or (H) any corporate or other action is taken by the Company or any Subsidiary of the Company for the purpose of effecting any of the foregoing;

(iii)The Company or any Subsidiary of the Company shall default in any of its obligations under any note, debenture, mortgage, credit agreement or other facility, in each case, constituting indebtedness for borrowed money, in an aggregate amount exceeding $500,000, whether such indebtedness now exists or shall hereafter be created, which default results in a right by a third party or parties, whether or not exercised, to accelerate the maturity of such indebtedness for borrowed money;

(iv)The Company’s common stock shall have been delisted from the Principal Market, after giving effect to all applicable notice, appeal, compliance and hearing periods;

(v)The Company shall have failed to issue the Warrant to the Holder;

(vi)The Company or any Subsidiary of the Company shall be a party to any Change of Control Transaction unless in connection with such Change of Control Transaction this Note is retired;

(vii)The Company’s (A) failure to deliver the required number of Common Shares to the Holder within two (2) Trading Days after the applicable Share Delivery Date (as defined in the Warrant) or (B) notice, written or oral, to any holder of this Note, including by way of public announcement, at any time, of its intention not to comply with a request for conversion of all or a portion of this Note into Common Shares that is tendered in accordance with the provisions of this Note;

(viii)The Company’s failure to timely file with the Commission any Periodic Report on or before the due date of such filing as established by the Commission, it being understood, for the avoidance of doubt, that due date includes any permitted filing deadline extension under Rule 12b-25 under the Exchange Act;

(ix)Any representation or warranty made or deemed to be made by or on behalf of the Company in or in connection with any Transaction Document, or any waiver hereunder or thereunder, shall prove to have been incorrect in any material respect (or, in the case of any such representation or warranty already qualified by materiality, such representation or warranty shall prove to have been incorrect) when made or deemed made;

(x)(A) Any material provision of any Transaction Document, at any time after its execution and delivery and for any reason other than as expressly permitted hereunder or thereunder, ceases to be in full force and effect; (B) the Company or any other Person contests in writing the validity or enforceability of any provision of any Transaction Document; or (C) the Company denies in writing that it has any or further liability or obligation under any Transaction Document, or purports in writing to revoke, terminate (other than in accordance with the relevant termination provisions) or rescind any Transaction Document;

(xi)The Company uses the proceeds of the issuance of this Note, whether directly or indirectly, and whether immediately, incidentally or ultimately, to purchase or carry margin stock (within the meaning of Regulations T, U and X of the Federal Reserve Board, as in effect from time to time and all official rulings and interpretations thereunder or thereof), or to extend credit to others for the purpose of purchasing or carrying margin stock or to refund indebtedness originally incurred for such purpose;

(xii)The Company shall fail to observe or perform any material covenant, agreement or warranty contained in, or otherwise commit any material breach or default of any provision of this Note (except as may be covered by Section (3)(a)(i) through Section 4(a)(xi) hereof) or any other Transaction Document, which is not cured or remedied within the time prescribed therein, or if no time is prescribed, within ten (10) Business Days;

(xiii)A final judgment or judgments for the payment of money aggregating in excess of $100,000 (or its foreign currency equivalent) (excluding any amounts covered by insurance) are rendered against the Company and shall remain unsatisfied and unstayed for a period of thirty (30) days; or

(xiv)The Company incurs any indebtedness for borrowed money other than (w) this Note, (x) under that certain Credit Agreement, dated as of November 1, 2024, by and between the Company and Export–Import Bank of the United States (the “EXIM Loan”), which loan proceeds are used for equipment financing, (y) indebtedness incurred on corporate credit cards in an aggregate amount outstanding at any time not to exceed $250,000, or (z) additional indebtedness of up to $900,000 outstanding at any time in the aggregate.

(b)During the time that any portion of this Note is outstanding, if any Event of Default has occurred and is continuing, (other than an event with respect to the Company described in Section (3)(a)(ii)), the full unpaid Principal amount of this Note, together with Interest and other amounts owing in respect thereof, to the date of acceleration shall become at the Holder’s election given by notice pursuant to Section (7), immediately due and payable in cash; provided that, in the case of any event with respect to the Company described in Section (3)(a)(ii), the full unpaid Principal amount of this Note, together with Interest and other amounts owing in respect thereof to the date of acceleration, shall automatically become due and payable, in each case without presentment, demand, protest or other notice of any kind, all of which are hereby waived by the Company. The Holder need not provide and the Company hereby waives any presentment, demand, protest or other notice of any kind, (other than required notice of conversion) and the Holder may immediately enforce any and all of its rights and remedies hereunder and all other remedies available to it under applicable law. Such declaration may be rescinded and annulled by the Holder in writing at any time prior to payment hereunder. No such rescission or annulment shall affect any subsequent Event of Default or impair any right consequent thereon. For the purposes hereof, an Event of Default relating to default in payment is “continuing” if it has not been waived, and an Event of Default relating to circumstances other than a default in payment is “continuing” if it has not been remedied or waived.

(4)CONDITIONS PRECEDENT. The obligation of the Holder to fund the Note shall be subject to the satisfaction, in the sole judgment of the Holder, of each of the following conditions:

(a)For the Issuance Date:

(i)The Company shall have duly executed and delivered to the Holder this Note.

(ii)The Company shall have duly executed and delivered to the Holder a Warrant for the number of Warrant Shares set forth opposite the Holder’s name on Schedule II attached hereto.

(iii)The Company shall have delivered to the Holder a certificate evidencing the good standing of the Company and its Subsidiaries executing Transaction Documents in the state of such Persons incorporation or organization, as applicable, as of a date within ten (10) days of the Issuance Date.

(iv)The Company shall have delivered to the Holder an Officer’s Certificate (the “Officer’s Certificate”) (A) certifying and attaching true, correct and complete copies of the (x) certificate of incorporation and by-laws of the Company and certificate(s) of incorporation or formation, as applicable, and by-laws or operating agreements, as applicable, of its Subsidiaries signatory to any document delivered under this Section (4)(a), and (y) duly adopted resolutions of the board of directors of the Company or other governing entity of such Subsidiaries (such resolutions to include approval of the transactions contemplated by the Transaction Documents delivered under this Section (4)(a)), (B) attaching a customary incumbency and (C) certifying that a majority of the voting power of the shares cast at the Company’s 2025 annual meeting of stockholders voted for the approval of the issuance of shares of common stock in excess of the Exchange Cap (as defined in the SEPA). The resolutions of the board of directors of the Company described herein have not been amended, rescinded or modified and remains in full force and effect as of the Issuance Date.

(v)Each and every representation and warranty of the Company and its Subsidiaries shall be true and correct in all material respects (other than representations and warranties qualified by materiality or Material Adverse Effect, which shall be true and correct in all respects) as of the date when made and as of the Issuance Date as though originally made at that time (except for representations and warranties that speak as of a specific date, which shall be true and correct as of such specific date) and the Company and its Subsidiaries shall have performed, satisfied and complied in all respects with the covenants, agreements and conditions set forth in each Transaction Document (in each case, without giving effect to any permissible time periods for performing, satisfying or complying with such covenants, agreements and conditions including without limitation, as set forth in this Agreement or in the Guaranty Agreement) to which it is a party required to be performed, satisfied or complied with by the Company or such Subsidiary.

(vi)No default, breach, event of default or Event of Default shall have occurred and be continuing immediately prior to or immediately following the issuance of this Note or the issuance of the Warrant for the number of Warrant Shares set forth opposite the Holder’s name on Schedule II attached hereto; and there are no facts or circumstances that with the giving of time or notice, if such facts or circumstances continue uncured, could give rise to a default, breach, event of default or Event of Default.

(vii)(A) The Common Shares shall continue to be listed on the Principal Market and shall not have been suspended or delisted, as of the Issuance Date, by the Commission or the Principal Market from trading on the Principal Market; and (B) except as set forth in the SEC Documents, the Company is in “good standing” with the Principal Market. The “SEC Documents” shall mean the reports, schedules, forms, statements and other documents required to be filed by the Company pursuant to the Exchange Act, as the same may be amended from time to time, and all information contained in such filings and all documents and disclosures that have been or may in the future be incorporated by reference therein.

(viii)No statute, rule, regulation, executive order, decree, ruling or injunction shall have been enacted, entered, promulgated or endorsed by any court or governmental entity of competent jurisdiction that prohibits the consummation of any of the transactions contemplated by the Transaction Documents.

(ix)The “Listing of Additional Shares” notification with respect to the Warrant Shares upon the exercise of the Warrant issued on the Issuance Date will be submitted to the Principal Market on the date hereof.

(x)The Holder shall have received the closing statement for Tranche One, in form and substance satisfactory to the Holder.

(xi)The Holder shall have received evidence that the Company has filed Prospectus Supplement No. 15 with the Commission, which amends and supplements the information in the prospectus supplement, dated July 11, 2025 and the base prospectus dated November 17, 2022, filed with the Commission as a part of the Company’s registration statement on Form S-3 (File No. 333-268138).

(xii)From and after the Issuance Date, the Company shall have publicly disclosed all material non-public information provided to the Holder by the Company or any of their respective officers, directors, employees, agents or representatives (if any) in connection with the Note as of the Issuance Date.

(xiii)The Company shall have filed a Current Report on Form 8-K with the Commission announcing the results of its 2025 annual meeting of stockholders, including the approval by the Company’s stockholders of the issuance of common stock by the Company up to the Exchange Cap.

(xiv)The Holder shall have received the opinion(s) of counsel to the Company and its Subsidiaries, dated as of the Issuance Date, in form and substance reasonably acceptable to the Holder, which opinion of counsel includes, among other items, customary opinions on the good standing, authority, execution and delivery of this Note and the Warrant, enforceability, and no conflicts, and the due authorization, validity and such other matters relating to this Note, the Warrant and Warrant Shares.

(b)For Tranche Two:

(i)An updated Schedule I attached hereto in form and substance satisfactory to the Holder.

(ii)The Company shall have delivered to the Holder a certificate evidencing the good standing of the Company and its Subsidiaries executing Transaction Documents in the state of such Persons incorporation or organization, as applicable, as of a date within ten (10) days of the Second Tranche Date.

(iii)The Company shall have delivered to the Holder a customary bring-down of the Officer’s Certificate.

(iv)Each and every representation and warranty of the Company and its Subsidiaries shall be true and correct in all material respects (other than representations and warranties qualified by materiality or Material Adverse Effect, which shall be true and correct in all respects) as of the date when made and as of the Second Tranche Date as though originally made at that time (except for representations and warranties that speak as of a specific date, which shall be true and correct as of such specific date) and the Company and its Subsidiaries shall have performed, satisfied and complied in all respects with the covenants, agreements and conditions set forth in each Transaction Document (in each case, without giving effect to any permissible time periods for performing, satisfying or complying with such covenants, agreements and conditions (including without limitation, as set forth in this Agreement or in the Guaranty Agreement) to which it is a party required to be performed, satisfied or complied with by the Company or such Subsidiary.

(v)No default, breach, event of default or Event of Default shall have occurred and be continuing immediately prior to or immediately following the issuance of this Note; and there are no facts or circumstances that with the giving of time or notice, if such facts or circumstances continue uncured, could give rise to a default, breach, event of default or Event of Default.

(vi)(A) The Common Shares shall continue to be listed on the Principal Market and shall not have been suspended or delisted, as of the Issuance Date, by the Commission or the Principal Market from trading on the Principal Market; and (B) except as set forth in the SEC Documents, the Company is in “good standing” with the Principal Market.

(vii)No statute, rule, regulation, executive order, decree, ruling or injunction shall have been enacted, entered, promulgated or endorsed by any court or governmental entity of competent jurisdiction that prohibits the consummation of any of the transactions contemplated by the Transaction Documents.

(viii)The Holder shall have received the closing statement for Tranche Two, in form and substance satisfactory to the Holder.

(ix)(A) the principal amount outstanding under Tranche One is equal to or less than $20,000,000, and (B) the Company (i) has entered into a customary sales agreement with Yorkville Securities, LLC (“Yorkville Securities”), as sole sales agent, for the potential issuance and sale of shares of common stock in an “at the market offering” as defined in Rule 415 of the Securities Act, and (ii) has filed a prospectus supplement pursuant thereto in an amount not less than $35,000,000.

(x)The Company shall have delivered to the Holder a compliance certificate executed by the chief executive officer or the chief financial officer of the Company certifying that Company and its Subsidiaries have complied with all of the conditions precedent to a closing for Tranche Two set forth herein and which may be relied upon by the Holder as evidence of satisfaction of such conditions without any obligation to independently verify such satisfaction.

(5)COVENANTS.

(a)Use of Proceeds. Until the Holder has received a Guaranty Agreement, in form and substance satisfactory to the Holder, duly executed by the Company and its Subsidiaries from time to time party thereto as required by Section (13) below, the Company shall not, directly or indirectly, use the proceeds from the Note, or lend, contribute or otherwise make available such proceeds to any Subsidiary of the Company that does not constitute an Excluded Subsidiary.

(b)New Subsidiaries. Until the Holder has received a Guaranty Agreement, in form and substance satisfactory to the Holder, duly executed by the Company and its Subsidiaries from time to time party thereto as required by Section (13) below, the Company shall not form or acquire any new Subsidiary, other than any Excluded Subsidiary, without the prior written consent of the Holder.

(c)No Liens. The Company shall not, and the Company shall cause each of its Subsidiaries to not, directly or indirectly, allow or suffer to exist any mortgage, lien, pledge, charge, security interest or other encumbrance upon or in any property or assets (including accounts and contract rights) (collectively, “Liens”) owned by the Company or its Subsidiaries, other than Permitted Liens .

(d)The Company shall use enter into a reasonable and customary at the market offering sales agreement with Yorkville Securities on or before October 31, 2025, naming Yorkville Securities as the sole agent and file an “at-the-market” supplement pursuant thereto in an amount not less than $35,000,000 (the “ATM Program”). Following the filing of the ATM prospectus supplement, the Company shall use its commercially reasonable efforts to furnish the required deliverables and activate the ATM Program. For the period after the repayment of any Principal under the Note and to the date ending twenty-four months from the date hereof, Yorkville shall be entitled to no less than 75% of the commissions under the ATM Program and the ATM Agreement may not be terminated.

(e)The Company shall have filed a shelf registration statement on Form S-3 no later than November 14, 2025 in accordance with Rule 415(a)(5) under the Securities Act, including a prospectus supplement for the SEPA and for the ATM Program.

(6)REISSUANCE OF THIS NOTE.

(a)Transfer. If this Note is to be transferred, the Holder shall surrender this Note to the Company, whereupon the Company will forthwith issue and deliver upon the order of the Holder a new Note (in accordance with Section (6)(d)), registered in the name of the registered transferee or assignee, representing the outstanding Principal being transferred by the Holder (along with any accrued and unpaid interest thereof) and, if less than the entire outstanding Principal is being transferred, a new Note (in accordance with Section (6)(d)) to the Holder representing the outstanding Principal not being transferred.

(b)Lost, Stolen or Mutilated Note. Upon receipt by the Company of evidence reasonably satisfactory to the Company of the loss, theft, destruction or mutilation of this Note, and, in the case of loss, theft or destruction, of any indemnification undertaking by the Holder to the Company in customary form and substance, and in the case of mutilation, upon surrender and cancellation of this Note, the Company shall execute and deliver to the Holder a new Note (in accordance with Section (6)(d)) representing the outstanding Principal.

(c)Note Exchangeable for Different Denominations. This Note is exchangeable, upon the surrender hereof by the Holder at the principal office of the Company, for a new Note or Notes (in accordance with Section (6)(d)) representing in the aggregate the outstanding Principal of this Note, and each such new Note will represent such portion of such outstanding Principal as is designated by the Holder at the time of such surrender.

(d)Issuance of New Notes. Whenever the Company is required to issue a new Note pursuant to the terms hereof, such new Note (i) shall be of like tenor with this Note, (ii) shall represent, as indicated on the face of such new Note, the Principal remaining outstanding (or in the case of a new Note being issued pursuant to Section (6)(a) or Section (6)(c), the Principal designated by the Holder which, when added to the Principal represented by the other new Note(s) issued in connection with such issuance, does not exceed the Principal remaining outstanding under this Note immediately prior to such issuance of such new Note), (iii) shall have an issuance date, as indicated on the face of such new Note, which is the same as the Issuance Date of this Note, (iv) shall have the same rights and conditions as this Note, and (v) shall represent accrued and unpaid Interest from the Issuance Date.

(7)NOTICES.    Any notices, consents, waivers or other communications required or permitted to be given under the terms hereof must be in writing by letter or electronic mail (“e-mail”) and will be deemed to have been delivered (i) upon receipt, when delivered personally, (ii) one (1) Business Day after deposit with an overnight courier service with next day delivery specified, as applicable or (iii) receipt, when sent by e-mail, and, in each case of the foregoing clauses (i), (ii) and (iii), properly addressed to the party to receive the same. The addresses and e­mail addresses for such communications shall be:

(8)

(9)or at such other address and/or email and/or to the attention of such other person as the recipient party has specified by written notice given to each other party in accordance with this Section at least three (3) Business Days prior to the effectiveness of such change. Written confirmation of receipt (i) given by the recipient of such notice, consent, waiver or other communication, (ii) electronically generated by the sender’s email service provider containing the time, date, recipient email address or (iii) provided by a nationally recognized overnight delivery service, shall be rebuttable evidence of personal service, receipt by email or receipt from a nationally recognized overnight delivery service in accordance with clause (i), (ii) or (iii) above, respectively.

(10)Except as expressly provided herein, no provision of this Note shall alter or impair the obligations of the Company, which are absolute and unconditional, to pay the Principal of, Interest and other charges (if any) on, this Note at the time, place, and rate, and in the currency, herein prescribed. This Note is a direct obligation of the Company. As long as this Note is outstanding, the Company shall not and shall cause its Subsidiaries not to, without the consent of the Holder, amend its certificate of incorporation, bylaws or other charter documents so as to adversely affect any rights of the Holder.

(11)CHOICE OF LAW; VENUE; WAIVER OF JURY TRIAL

(a)Governing Law. This Note and the rights and obligations of the parties hereunder shall, in all respects, be governed by, and construed in accordance with, the laws (excluding the principles of conflict of laws) of the State of New York (the “Governing Jurisdiction”) (including Section 5-1401 and Section 5-1402 of the General Obligations Law of the State of New York), including all matters of construction, validity and performance.

(b)Jurisdiction; Venue; Service.

(i)The Company hereby irrevocably consents to the non-exclusive personal jurisdiction of the state courts of the Governing Jurisdiction and, if a basis for federal jurisdiction exists, the non-exclusive personal jurisdiction of any United States District Court for the Governing Jurisdiction selected by the Holder.

(ii)The Company agrees that venue shall be proper in any court of the Governing Jurisdiction selected by the Holder or, if a basis for federal jurisdiction exists, in any United States District Court in the Governing Jurisdiction. The Company waives any right to object to the maintenance of any suit, claim, action, litigation or proceeding of any kind or description, whether in law or equity, whether in contract or in tort or otherwise, in any of the state or federal courts of the Governing Jurisdiction on the basis of improper venue or inconvenience of forum.

(iii)Any suit, claim, action, litigation or proceeding of any kind or description, whether in law or equity, whether in contract or tort or otherwise, brought by the Company against the Holder arising out of or based upon this Note or any matter relating to this Note, or any other Transaction Document, or any contemplated transaction, shall be brought in a court only in the Governing Jurisdiction. The Company shall not file any counterclaim against the Holder in any suit, claim, action, litigation or proceeding brought by the Holder against the Company in a jurisdiction outside of the Governing Jurisdiction unless under the rules of the court in which the Holder brought such suit, claim, action, litigation or proceeding the counterclaim is mandatory, and not permissive, and would be considered waived unless filed as a counterclaim in the suit, claim, action, litigation or proceeding instituted by the Holder against the Company. The Company agrees that any forum outside the Governing Jurisdiction is an inconvenient forum and that any suit, claim, action, litigation or proceeding brought by the Company against the Holder in any court outside the Governing Jurisdiction should be dismissed or transferred to a court located in the Governing Jurisdiction. Furthermore, the Company irrevocably and unconditionally agrees that it will not bring or commence any suit, claim, action, litigation or proceeding of any kind or description, whether in law or equity, whether in contract or in tort or otherwise, against the Holder arising out of or based upon this Note or any matter relating to this Note, or any other Transaction Document, or any contemplated transaction, in any forum other than the courts of the State of New York sitting in New York County, and the United States District Court of the Southern District of New York, and any appellate court from any thereof, and each of the parties hereto irrevocably and unconditionally submits to the jurisdiction of such courts and agrees that all claims in respect of any such suit, claim, action, litigation or proceeding may be heard and determined in such New York State Court or, to the fullest extent permitted by applicable law, in such federal court. The Company and the Holder agree that a final judgment in any such suit, claim, action, litigation or proceeding shall be conclusive and may be enforced in other jurisdictions by suit on the judgment or in any other manner provided by law.

(iv)The Company and the Holder irrevocably consent to the service of process out of any of the aforementioned courts in any such suit, claim, action, litigation or proceeding by e-mail or the mailing of copies thereof by registered or certified mail postage prepaid, to it at the e-mail address or physical address, as applicable, provided for notices in this Note, such service to become effective thirty (30) days after the date of such e-mail or mailing, as applicable. The Company and the Holder each irrevocably waive any defense it may have on the grounds of insufficient or improper service with respect to service of process effected in accordance with this Section (9)(b)(iv).

(v)Nothing herein shall affect the right of the Holder to serve process in any other manner permitted by law or to commence legal proceedings or to otherwise proceed against the Company or any other Person in the Governing Jurisdiction or in any other jurisdiction.

(c)THE PARTIES MUTUALLY WAIVE ALL RIGHT TO TRIAL BY JURY OF ALL CLAIMS OF ANY KIND ARISING OUT OF OR BASED UPON THIS NOTE OR ANY MATTER RELATING TO THIS NOTE, OR ANY OTHER TRANSACTION DOCUMENT, OR ANY CONTEMPLATED TRANSACTION. THE PARTIES ACKNOWLEDGE THAT THIS IS A WAIVER OF A LEGAL RIGHT AND THAT THE PARTIES EACH MAKE THIS WAIVER VOLUNTARILY AND KNOWINGLY AFTER CONSULTATION WITH COUNSEL OF THEIR RESPECTIVE CHOICE. THE PARTIES AGREE THAT ALL SUCH CLAIMS SHALL BE TRIED BEFORE A JUDGE OF A COURT HAVING JURISDICTION, WITHOUT A JURY.

(12)If the Company fails to strictly comply with the terms of this Note, then the Company shall reimburse the Holder promptly for all fees, costs and expenses, including, without limitation, reasonable and documented attorneys’ fees and expenses incurred by the Holder in any action in connection with this Note, including, without limitation, those incurred: (i) during any workout, attempted workout, and/or in connection with the rendering of legal advice as to the Holder’s rights, remedies and obligations, (ii) collecting any sums which become due to the Holder, (iii) defending or prosecuting any proceeding or any counterclaim to any proceeding or appeal; or (iv) the protection, preservation or enforcement of any rights or remedies of the Holder.

(13)Any waiver by the Holder of a breach of any provision of this Note shall not operate as or be construed to be a waiver of any other breach of such provision or of any breach of any other provision of this Note. The failure of the Holder to insist upon strict adherence to any term of this Note on one or more occasions shall not be considered a waiver or deprive that party of the right thereafter to insist upon strict adherence to that term or any other term of this Note. No provision of this Note may be waived or amended other than by a written agreement signed by the parties to this Note.

(14)If any provision of this Note is invalid, illegal or unenforceable, the balance of this Note shall remain in effect, and if any provision is inapplicable to any person or circumstance, it shall nevertheless remain applicable to all other persons and circumstances. If it shall be found that any interest or other amount deemed interest due hereunder shall violate applicable laws governing usury, the applicable rate of interest due hereunder shall automatically be lowered to equal the maximum permitted rate of interest. The Company covenants (to the extent that it may lawfully do so) that it shall not at any time insist upon, plead, or in any manner whatsoever claim or take the benefit or advantage of, any stay, extension or usury law or other law which would prohibit or forgive the Company from paying all or any portion of the Principal of or Interest on this Note as contemplated herein, wherever enacted, now or at any time hereafter in force, or which may affect the covenants or the performance of this Note, and the Company (to the extent it may lawfully do so) hereby expressly waives all benefits or advantage of any such law, and covenants that it will not, by resort to any such law, hinder, delay or impede the execution of any power herein granted to the Holder, but will suffer and permit the execution of every such power as though no such law has been enacted.

(15)GUARANTY.

(a)The Company shall, and shall cause each Subsidiary (other than any Excluded Subsidiary) to guarantee the obligations under this Note as set forth the Guaranty Agreement referred to below.

(b)Subject to Section 5(b), within thirty (30) days of the formation or acquisition of any new Subsidiary or any Subsidiary ceasing to be an Excluded Subsidiary, the Company shall cause such Subsidiary (other than any Excluded Subsidiary) (i) to execute and deliver a joinder agreement to the Guaranty Agreement, (ii) to do and perform, or cause to be done and performed, all such further acts and things necessary to cause the new Subsidiary to become a guarantor under the Guaranty Agreement, and (iii) to deliver all such other agreements, certificates, instruments, opinion letters, information, and documents, each in form and substance reasonably satisfactory to the Holder, as the Holder may reasonably request in order to carry out the intent and accomplish the purposes of this Section (13).

(c)The Company shall, and shall cause each of its Subsidiaries (other than any Excluded Subsidiary), to do and perform, or cause to be done and performed, all such further acts and things, and shall execute and deliver all such other agreements, certificates, instruments and documents, each in form and substance reasonably satisfactory to the Holder, as the Holder may reasonably request in order to carry out the intent and accomplish the purposes of this Section (13). 

(16)CERTAIN DEFINITIONS. For purposes of this Note, the following terms shall have the following meanings:

(a)“Business Day” means any day except Saturday, Sunday and any day which shall be a federal legal holiday in the United States or a day on which banking institutions are authorized or required by law or other government action to close.

(b)“Change of Control Transaction” means the occurrence of (a) an acquisition after the date hereof by an individual or legal entity or “group” (as described in Rule 13d-5(b)(1) promulgated under the Exchange Act) of effective control (whether through legal or beneficial ownership of capital stock of the Company, by contract or otherwise) of in excess of fifty percent (50%) of the voting power of the Company (except that the acquisition of voting securities by the Holder or any other current holder of convertible securities of the Company shall not constitute a Change of Control Transaction for purposes hereof), (b) a replacement at one time or over time of more than one-half of the members of the board of directors of the Company (other than as due to the death or disability of a member of the board of directors) which is not approved by a majority of those individuals who are members of the board of directors on the date hereof (or by those individuals who are serving as members of the board of directors on any date whose nomination to the board of directors was approved by a majority of the members of the board of directors who are members on the date hereof), or (c) the sale of substantially all of the assets of the Company and its Subsidiaries, taken as a whole, in one or a series of related transactions with or into another entity. No transfers between the Company and its Subsidiaries shall be deemed a Change of Control Transaction under this provision.

(c)“Commission” means the Securities and Exchange Commission.

(d)“Common Shares” means the shares of common stock, par value $0.0001, of the Company and stock of any other class into which such shares may hereafter be changed or reclassified.

(e)“Exchange Act” means the Securities Exchange Act of 1934, as amended.

(f)“Excluded Subsidiary” means any of the following: (i) each Immaterial Subsidiary, and (ii) any foreign subsidiary, any subsidiary of a foreign subsidiary, or subsidiary which is a foreign sales office and does not own any material assets.

(g)“Guaranty Agreement” means a certain guaranty agreement among the Company and its Subsidiaries party thereto from time to time and the Holder (as amended, amended and restated, supplemented or otherwise modified from time to time) in a form to be agreed between Company, its Subsidiaries and the Holder.

(h)“Immaterial Subsidiary” means any Subsidiary of the Company that does not have (i) revenue, determined on a consolidated basis with its Subsidiaries, as of the last day of the most recently ended four fiscal quarter period as of such date, in excess of 2.5% of the aggregate revenue of the Company and its Subsidiaries, on a consolidated basis, for such period or (ii) as of the date of determination, total assets, determined on a consolidated basis with its Subsidiaries, at any time, in excess of 2.5% of the consolidated total assets of the Company and its Subsidiaries, on a consolidated basis, as such date; provided that (x) the aggregate amount of revenue of Subsidiaries constituting Immaterial Subsidiaries, as of the last day of the most recently ended four fiscal quarter period, shall not exceed 5% of the aggregate revenue of the Company and its Subsidiaries, on a consolidated basis, for such period and (y) as of any date of determination, the total assets of Subsidiaries constituting Immaterial Subsidiaries shall not at any time exceed 5% of the consolidated total assets of the Company and its Subsidiaries, on a consolidated basis as of such date.

(i)“Material Adverse Effect” shall mean any of (i) a material adverse effect on the results of operations, assets, business or financial condition of the Company, taken as a whole, or (ii) a material adverse effect on the Company’s ability to perform in any material respect on a timely basis its obligations under the Transaction Documents.

(j)“Other Notes” means any other notes issued pursuant to the SEPA and any other debentures, notes, or other instruments issued in exchange, replacement, or modification of the foregoing.

(k)“Periodic Reports” shall mean all of the Company’s reports required to be filed by the Company with the Commission under applicable laws and regulations (including, without limitation, Regulation S-K), including annual reports (on Form 10-K), quarterly reports (on Form 10-Q), and current reports (on Form 8-K), for so long as any amounts are outstanding under this Note or any Other Note; provided that all such Periodic Reports shall include, when filed, all information, financial statements, audit reports (when applicable) and other information required to be included in such Periodic Reports in compliance with all applicable laws and regulations.

(l)“Permitted Liens” are:

(i)Liens for taxes, fees, assessments or other government charges or levies, either (i) not due and payable or (ii) being contested in good faith and for which Borrower maintains adequate reserves on the Company’s books;

(ii)Liens of carriers, warehousemen, suppliers, or other Persons that are possessory in nature arising in the ordinary course of business so long as such Liens attach only to Inventory and which are not delinquent or remain payable without penalty or which are being contested in good faith and by appropriate proceedings which proceedings have the effect of preventing the forfeiture or sale of the property subject thereto;

(iii)purchase money Liens and Liens securing capital leases (i) on equipment acquired or held by Borrower incurred for financing the acquisition of the equipment, or (ii) existing on equipment when acquired, if the Lien is confined to the property and improvements and the proceeds of the equipment;

(iv)Liens to secure payment of workers’ compensation, employment insurance, old-age pensions, social security and other like obligations incurred in the ordinary course of business (other than Liens imposed by ERISA);

(v)leases or subleases of real property granted in the ordinary course of the Company and its Subsidiaries’ business (or, if referring to another Person, in the ordinary course of such Person’s business), and leases, subleases, non-exclusive licenses or sublicenses of personal property (other than intellectual property) granted in the ordinary course of Borrower’s business (or, if referring to another Person, in the ordinary course of such Person’s business);

(vi)non-exclusive licenses of intellectual property granted to third parties in the ordinary course of business, and licenses of intellectual property that could not result in a legal transfer of title of the licensed property that may be exclusive in respects other than territory and that may be exclusive as to territory only as to discreet geographical areas outside of the United States;

(vii)Liens arising from attachments or judgments, orders, or decrees in circumstances not constituting an Event of Default under Sections 3(a)(xiii);

(viii)easements, rights-of-way, restrictions and other similar encumbrances affecting real property which, in the aggregate, are not substantial in amount, and which do not in any case materially detract from the value of the property subject thereto or materially interfere with the ordinary conduct of the business of the applicable Person;

(ix)Liens in favor of customs or revenue authorities arising as a matter of law to secure payment of customs duties in connection with the importation of goods;

(x)deposits to secure the performance of bids, trade contracts, leases, statutory obligations, surety and appeal bonds, performance bonds and other obligations of a like nature, in each case, in the ordinary course of business;

(xi)Liens on cash collateral to secure credit card obligations and reimbursement obligations under letters of credit;

(xii)customary Liens of any bank in connection with statutory, common law and contractual rights of setoff and recoupment with respect to any deposit account or securities account of the Company or its Subsidiaries; and

(xiii)Liens in connection with the EXIM Loan.

(m)“Person” shall mean a corporation, an association, a partnership, organization, a business, an individual, a government or political subdivision thereof or a governmental agency.

(n)“Principal Market” shall mean The New York Stock Exchange, and any successor to any of the foregoing markets or exchanges.

(o)“Securities Act” shall mean the Securities Act of 1933, as amended, and the rules and regulations promulgated thereunder.

(p)“SEPA” means the Standby Equity Purchase Agreement entered into between the Company and the Holder on July 16, 2024, as may be amended, amended and restated, extended, supplemented or otherwise modified in writing from time to time.

(q)“Subsidiary” shall mean any Person in which the Company, directly or indirectly, (x) owns a majority of the outstanding capital stock or holds a majority of the equity or similar interest of such Person or (y) controls or operates all or substantially all of the business, operations or administration of such Person, and the foregoing are collectively referred to herein as “Subsidiaries.”

(r)“Trading Day” means a day on which the Common Shares are quoted or traded on a Principal Market on which the Common Shares are then quoted or listed; provided, that in the event that the Common Shares are not listed or quoted, then Trading Day shall mean a Business Day.

(s)“Tranche One” shall mean the transactions occurring on the Issuance Date.

(t)“Tranche Two” shall mean the transactions occurring on the Second Tranche Date.

(u)“Transaction Documents” means, collectively, this Note, each of the Other Notes, the SEPA, the Warrant, the Guaranty Agreement, and any and all documents, agreements, instruments or other items executed or delivered in connection with any of the foregoing.

(v)“Warrant” means the warrant issued by the Company to the Holder as of the date hereof that allows the Holder to acquire up to an aggregate number of shares of Common Shares as set forth in the Warrant, substantially in the form attached hereto as Exhibit A (the “Warrant”) (as exercised, collectively, the “Warrant Shares”).

(w)

IN WITNESS WHEREOF, the Company has caused this Promissory Note to be duly executed by a duly authorized officer as of the date set forth above.

SCHEDULE I
REPAYMENT SCHEDULE

Wilsonville, Ore.– October 14, 2025 - ESS Tech, Inc. (“ESS” or the “Company”) (NYSE:GWH), a leading manufacturer of iron flow long-duration energy storage systems for commercial- and utility-scale applications, today announced the closing of a $40 million financing transaction with YA II PN, Ltd., an investment fund managed by Yorkville Advisors Global, L.P. (“Yorkville”). The financing provides $30 million of immediate capital, with an additional $10 million available upon execution of an at-the-market sales agreement with Yorkville Securities, LLC, an affiliate of Yorkville, subject to customary conditions, and in each case less an original issue discount and certain fees and expenses. The transaction is structured as a one-year promissory note, repayable in cash or from a portion of the proceeds raised from equity issuances under the Company’s existing or future capital raising arrangements. Additional details regarding the transaction are included in the Company’s Current Report on Form 8-K filed this morning.

This capital strengthens the Company’s cash position and reflects continued progress in the strategic pivot to the U.S.-manufactured Energy Base. Over the past nine months, ESS has executed against an intentional sequence: strengthening its leadership team, securing landmark customer agreements, including the recently announced 50 MWh New Horizon project for Salt River Project, and now reinforcing its balance sheet with additional funding. With these building blocks in place, the Company’s focus is firmly on execution and delivery on existing commitments while positioning to sign new contracts for long-duration energy storage.

“Today’s financing marks another key milestone as we move into the execution and delivery phase of our strategy,” said Kelly Goodman, Interim Chief Executive Officer. “ESS is well positioned to deliver the Energy Base platform to customers – including in the rapidly growing digital infrastructure sector – to help meet the growing demand for reliable, long-duration energy storage solutions.”

At ESS (NYSE: GWH), we deliver safe, sustainable, long-duration energy storage to ensure energy abundance and security. As energy demand continues to grow, our solutions provide essential reliability and resilience to people, communities, and businesses in the United States and throughout the world. Our technology uses earth-abundant iron, salt and water to deliver environmentally safe solutions capable of providing 10+ hours of flexible energy capacity for commercial and utility-scale energy storage applications. Established in 2011, ESS enables project developers, independent power producers, utilities and other large energy users to deploy reliable, sustainable long-duration energy storage solutions. For more information visit www.essinc.com. 

This release contains certain forward-looking statements, including statements regarding the Company and its management team’s expectations, hopes, beliefs, intentions or strategies regarding the future. The words “anticipate”, “believe”, “continue”, “could”, “estimate”, “expect”, “intends”, “may”, “might”, “plan”, “possible”, “potential”, “predict”, “project”, “should”, “will” and “would” and similar expressions may identify forward-looking statements, but the absence of these words does not mean that a statement is not forward-looking. Examples of forward-looking statements include, among others, statements regarding the additional funding from Yorkville, the Salt Lake River project and the Company executing on its near-term strategy. These forward-looking statements are based on the Company’s current expectations and beliefs concerning future developments and their potential effects on the Company and involve a number of risks, uncertainties (some of which are beyond the Company’s control) or other assumptions that may cause actual results or performance to be materially different from those expressed or implied by these forward-looking statements, which include, but are not limited to, partnerships and customer relationships not resulting in expectant benefits, and the Company’s inability to close on the additional funding from Yorkville, to repay the promissory notes, to raise additional capital and to obtain stockholder approval, if required, and other risks and uncertainties described more fully in the section titled “Risk Factors” in the Company’s Quarterly Report on Form 10-Q filed on August 14, 2025, and the Company’s other filings with the U.S. Securities and Exchange Commission. Except as required by law, the Company is not undertaking any obligation to update or revise any forward-looking statements whether as a result of new information, future events or otherwise.

Investors:

investors@essinc.com

Media:

(855) 423-9920