UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

~~Washington~~WASHINGTON, D.C. 20549

FORM 6-K

REPORT OF FOREIGN PRIVATE ISSUER PURSUANT TO RULE 13a-16 OR 15d-16

UNDER THE SECURITIES EXCHANGE ACT OF 1934

For the month of October 2025

Commission File Number: 001-36885

TANTECH HOLDINGS LTD

(Translation of registrant’s name into English)

No. 10 Cen Shan Road, Shuige Industrial Zone

Lishui City, Zhejiang Province 323000

~~People’s Republic of China 323000~~+86-578-226-2305

(Address of principal executive offices)

Indicate by check mark whether the registrant files or will file annual reports under cover Form 20-F or Form 40-F.

Form 20-F ☒ Form 40-F ☐

~~EXPLANATORY~~Explanatory ~~NOTE~~Note:

~~Note~~On October 23, 2025, Tantech Holdings Ltd, a British Virgin Islands company (the “Company”), entered into a securities purchase agreement (the “Purchase Agreement”) with certain accredited investors (the “Purchasers”), pursuant to which the Company agreed to issue and sell to the Purchasers, and the Purchasers agreed to purchase from the Company, an aggregate of 3,614,464 common shares, no par value per share, (the “Common Shares”) of the Company, Series C warrants (the “Series C Warrants”) to purchase up to 10,843,392 Common Shares (the “Series C Warrant Shares”), and Series D warrants (the “Series D Warrants,” and together with the Series C Warrants, the “Warrants”) to purchase up to 10,843,392 Common Shares (the “Series D Warrant Shares,” and together with the Series C Warrant Shares, the “Warrant Shares”) in a private placement for gross proceeds of $6.0 million (the “Offering”). The Company will use the proceeds from this Offering for working capital and general corporate purposes.

OnPursuant ~~October~~to ~~14,~~the ~~2025~~Purchase Agreement, ~~Tantech~~the ~~Holdings~~Company ~~Ltd~~will (sell to the ~~“Company”)~~Purchasers ~~entered~~an ~~into~~aggregate aof ~~note~~3,614,464 ~~purchase~~units ~~agreement~~at ~~(the~~a ~~“Purchase~~purchase ~~Agreement”)~~price ~~with~~of ~~Streeterville~~$1.66 ~~Capital,~~per ~~LLC,~~unit. aEach ~~Utah~~unit ~~limited~~consists ~~liability~~of ~~company~~one ~~(“Streeterville”)~~Common Share, ~~pursuant~~three Series C Warrants each to ~~which~~purchase ~~the~~one ~~Company~~Common ~~issued~~Share, and ~~sold~~three Series D Warrants each to ~~Streeterville~~purchase one Common Share. The Warrants will be exercisable immediately upon issuance and will have a ~~promissory~~term ~~note~~of inthree ~~the~~years ~~original~~from ~~principal~~the ~~amount~~date of ~~$3,230,000~~issuance.00 ~~(the~~The ~~“Note”)~~Series ~~for~~C Warrants will have an exercise price of $~~3,000,000~~1.0066 inper ~~gross~~Common ~~proceeds~~Share. The ~~transaction~~Series ~~closed~~D onWarrants ~~October~~will ~~14,~~have ~~2025~~an exercise price of $1.83 per Common Share. The ~~Company~~exercise ~~will~~price ~~use~~and the ~~net~~number ~~proceeds~~of ~~from~~Warrant Shares are subject to adjustment upon the ~~offering~~occurrence of ~~the~~certain ~~Note~~events, ~~for~~including ~~working~~share ~~capital~~combination ~~and~~or ~~general~~similar ~~business~~recapitalization ~~purposes~~transactions.

~~The~~These ~~Purchase~~securities ~~Agreement~~were offered pursuant to an exemption from the registration requirements of Section 5 of the Securities Act of 1933, as amended (the “Securities Act”), contained in Section 4(a)(2) thereof and/or Regulation D promulgated thereunder. No placement agent was involved in the private placement. Each Purchaser understands that the securities offered in this Offering have not been registered under the Securities Act and may not be sold absent registration or an applicable exemption from the registration requirements of the Securities Act.

Pursuant to ~~the~~a ~~terms~~registration ofrights agreement the ~~Purchase~~Company ~~Agreement,~~entered ~~until~~into ~~all~~with of the ~~Company’s~~Purchasers, ~~obligations under~~ the ~~Note~~Company ~~and~~has ~~other~~agreed ~~transaction~~to ~~documents~~file ~~are~~a ~~paid~~resale ~~and~~registration ~~performed~~statement inon ~~full,~~behalf the ~~Company~~Purchasers ~~shall~~to ~~comply~~register ~~with~~the ~~certain~~resale ~~covenants,~~of ~~including~~the ~~but~~Warrants ~~not~~and ~~limited~~Warrant ~~to:~~Shares ~~(i)~~within ~~compliance~~60 ~~with~~days ~~its~~of ~~filing~~the ~~and~~closing ~~other~~of ~~requirements under~~ the ~~Securities~~Offering, ~~Exchange~~and ~~Act~~to ofuse ~~1934,~~commercially asreasonable ~~amended,~~efforts ~~(ii)~~to ~~maintaining~~cause ~~the~~such ~~Company’s~~registration ~~listing~~to onbecome ~~NASDAQ~~effective orwithin ~~New~~120 ~~York~~days ~~Stock~~of ~~Exchange,~~the ~~and~~closing ~~(iii)~~of ~~refraining~~the ~~from~~Offering ~~making~~if ~~any~~subject ~~Restricted~~to ~~Issuances~~full ~~(as~~review ~~defined~~by in the ~~Purchase~~SEC, ~~Agreement~~ and ~~described~~to ~~below)~~keep ~~without~~such ~~the~~registration ~~Streeterville’s~~statement ~~prior~~effective ~~written~~at ~~consent,~~all ~~which~~times ~~consent~~until ~~may~~no beinvestor ~~granted~~owns orany ~~withheld~~of inthe ~~Streeterville’s~~Warrants ~~sole~~or ~~discretion~~Warrant Shares.

~~Restricted~~The ~~Issuances~~Company ~~include,~~also ~~subject~~entered tointo ~~certain~~a ~~limited~~financial ~~exceptions,~~advisory ~~the~~agreement ~~incurrence~~date orOctober ~~guaranty~~23, of2025 ~~any~~(the ~~debt~~“Financial ~~obligations~~Advisory ~~other~~Agreement”) ~~than~~with ~~trade~~Aegis ~~payables~~Capital inCorp. ~~the ordinary course of business~~(“Aegis”), ~~the~~pursuant ~~issuance~~to ofwhich ~~any~~Aegis ~~convertible~~agreed ~~securities~~to inserve ~~which~~as the ~~number~~exclusive offinancial ~~shares~~advisor ~~that~~for ~~may be issued pursuant to a conversion right, or~~ the ~~conversion~~Company ~~price,~~in ~~varies~~connection with the ~~market~~Offering. ~~price~~The ~~of the~~ Company’s ~~common~~agreed ~~shares,~~to ~~the~~pay ~~issuance~~Aegis ofa ~~any~~cash ~~securities~~fee ~~with~~equal ~~reset~~to ~~provisions~~4.0% ~~and~~of the ~~issuance~~gross ofproceeds ~~any~~received ~~securities~~ in ~~connection~~this ~~with~~Offering ~~Section~~and ~~3(a)(9)~~to ~~exchange,~~pay afor ~~Section~~expenses ~~3(a)(10)~~of ~~settlement,~~Aegis’s orlegal ~~any~~counsel ~~other~~up ~~similar~~to ~~settlement~~an oraggregate ~~exchange.~~amount of $100,000.

~~Pursuant~~The todescriptions of the Purchase Agreement, ~~until~~ the ~~Note~~Registration isRights ~~paid in full~~Agreement, ~~subject~~the toFinancial ~~certain~~Advisory ~~limited exceptions~~Agreement, ~~Streeterville~~and ~~has~~ the ~~right~~Warrants toset ~~participate~~forth inabove upare toqualified ~~30%~~in oftheir ~~any~~entirety ofby ~~the~~reference ~~Company’s~~to ~~convertible debt financings and, in~~ the ~~event~~full atext ~~breach~~ of ~~such~~those ~~obligations by the Company~~documents, iswhich ~~entitle~~are toattached ~~receive,~~hereto as ~~liquidated~~Exhibits ~~damages~~10.1, an10.2, ~~amount~~10.3, ~~equal~~4.1 toand ~~20% of the investment amount Streeterville would be entitled to under such participation right~~4.2, respectively.

~~The~~This ~~Note~~Report on Form 6-K shall not constitute an offer to sell or the solicitation of an offer to buy the securities, nor shall there be any sale of these securities in any state or jurisdiction in which such offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such state or jurisdiction.

The Note bears interest at a rate of 7% per annum and has a term of twelve (12) months after Streeterville delivers the purchase price of the Note (the “Purchase Price Date”). The Note carries an original issue discount of $210,000.00 and includes $20,000.00 for Streeterville’s legal fees, accounting costs, and other transaction expenses in connection with the purchase and sale of the Note. The Company may prepay all or a portion of the Note at any time by paying 105% of the outstanding balance elected for pre-payment. Commencing six months from the Purchase Price Date until the Note is paid in full, Streeterville has the right to redeem up to $750,000.00 of the outstanding balance per calendar month. The Company must pay the redeemed amount in cash within three (3) trading days of receiving a redemption notice.

Pursuant to the terms of the Note, upon the occurrence of a Trigger Event (as defined in the Note), Streeterville may increase the balance of the Note by 10% for each Major Trigger Event (as defined in the Note) and 5% for each Minor Trigger Event (as defined in the Note), with an aggregate of 25% as the maximum increase in the outstanding balance. If the Company fails to cure a Trigger Event within 10 trading days after receipt of written notice, Streeterville may elect to notify the Company that the Trigger Event become an Event of Default. Upon the occurrence of an Event of Default, Streeterville may accelerate the Note, with the outstanding balance becoming immediately due and payable in cash, and raise interest on the outstanding balance of the Note to accrue at a rate equal to the lesser of 15% per annum or the maximum rate permitted under applicable law. Certain Trigger Events, such as bankruptcy or insolvency, automatically result in an Event of Default and the outstanding balance becomes immediately and automatically due and payable in cash.

~~The~~Cautionary ~~foregoing descriptions of the Purchase Agreement and the~~ Note ~~are~~Regarding ~~summaries~~Forward-Looking of the material terms of such agreements, do not purport to be complete and are qualified in their entirety by reference to the Purchase Agreement and the Note, which are attached hereto as Exhibits 10.1 and 10.2. Statements

~~Exchange~~This ~~Agreements~~Report of Foreign Private Issuer on Form 6-K contains “forward-looking statements” within the meaning of the Private Securities Litigation Reform Act and other securities laws. Words such as “expects,” “anticipates,” “intends,” “plans,” “believes,” “seeks,” “estimates” and similar expressions or variations of such words are intended to identify forward-looking statements. For example, the Company is using forward-looking statements when it discusses the closing of the Private Placement and anticipated use of proceeds from the Private Placement. Forward-looking statements are not historical facts, and are based upon management’s current expectations, beliefs and projections, many of which, by their nature, are inherently uncertain. Such expectations, beliefs and projections are expressed in good faith. However, there can be no assurance that management’s expectations, beliefs or projections will be achieved, and actual results may differ materially from what is expressed in, or indicated by, the forward-looking statements. Forward-looking statements are subject to risks and uncertainties that could cause actual performance or results to differ materially from those expressed in the forward-looking statements. For a more detailed description of the risks and uncertainties affecting the Company, reference is made to the Company’s reports filed from time to time with the SEC. Forward-looking statements speak only as of the date the statements are made. The Company assumes no obligation to update forward-looking statements to reflect actual results, subsequent events or circumstances, changes in assumptions or changes in other factors affecting forward-looking information except to the extent required by applicable securities laws. If the Company does update one or more forward-looking statements, no inference should be drawn that the Company will make additional updates with respect thereto or with respect to other forward-looking statements.

OnExhibit October 2 through October 15, 2025, the Company entered into five exchange agreements with Streeterville. Pursuant to each agreement, the parties agreed to partition a new promissory note (each, a “New Note”) from the promissory note the Company issued to Streeterville on August 1, 2024, in the original principal amount of $2,160,000.00 (the “August 2024 Note”), and exchange each partitioned New Note for the Company’s common shares. Index

Pursuant to the agreements, the Company exchanged: (i) a partitioned New Note in the principal amount of $100,000.00 for the issuance of 71,225 common shares on October 3, 2025, (ii) a New Note in the principal amount of $100,000.00 for 70,224 common shares on October 10, 2025, (iii) a New Note in the principal amount of $105,000.00 for 73,735 common shares on October 9, 2025, (iv) a New Note in the principal amount of $110,000.00 for 74,728 common shares on October 10, 2025, and (v) a New Note in the principal amount of $105,000.00 for 75,431 common shares on October 16, 2025.

Exhibit Number		Description of Exhibit
4.1		Form of Series C Warrant
4.2		Form of Series D Warrant
10.1		Securities Purchase Agreement, dated October 23, 2025, by and between the Company and the Purchasers
10.2		Registration Rights Agreement, dated October 23, 2025, by and between the Company and the Purchasers
10.3		Financial Advisory Agreement, dated October 23, 2025, by and between the Company and Aegis Capital Corp.

The issuances of the above-referenced common shares of the Company were pursuant to the exemption from the registration requirements afforded by Section 3(a)(9) of the Securities Act of 1933, as amended.

The foregoing descriptions of the exchange agreements are summaries of certain material terms of such agreements and are qualified in their entirety by reference to the exchange agreements, which are in the form of or substantially similar to the exchange agreement dated October 15, 2025, attached hereto as Exhibit 10.3.

EXHIBIT INDEX

Exhibits No.		Description
10.1		Note Purchase Agreement with Streeterville Capital, LLC, dated October 14, 2025
10.2		Promissory Note, dated October 14, 2025
10.3		Exchange Agreement with Streeterville Capital, LLC, dated October 15, 2025

SIGNATURE

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

	Tantech Holdings Ltd
Date: October 17, 2025	By:	/s/ Zheyuan Liu
Date: October 23, 2025	By:	/s/ Zheyuan Liu
		Zheyuan Liu
		Chief Executive Officer

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