Oxidized sulfur heterocycles for non-aqueous redox fl0w batteries

Patent metadata

Field	Value
Publication number	US-2026031380-A1
Application number	US-202519090174-A
Country	US
Kind code	A1
Filing date	Mar 25, 2025
Priority date	Mar 26, 2024
Publication date	Jan 29, 2026
Grant date	—

Abstract

Disclosed herein are a variety of systems, compositions, and methods for reversibly storing electrical energy in a redox flow battery with a unit cell potential equal to or greater than 3.0 volts (V). The system may include an electroactive redox molecule, a positive section, and a negative section. The electroactive redox molecule may comprise an anolyte moiety comprising a multi-ring conjugated system comprising at least one sulfone group, wherein an anolyte reaction occurs at a cell potential less than −1.50 V. The positive section may comprise a first metal electrode in contact with the electroactive bipolar redox molecule and a supporting electrolyte dissolved in a solvent. The negative section may comprise a second metal electrode in contact with the electroactive bipolar redox molecule and additional electrolyte dissolved in additional solvent.

First claim

What is claimed is:

1 . A system for energy storage comprising:
an electroactive redox molecule comprising an anolyte moiety comprising a multi-ring conjugated system comprising at least one sulfone group, wherein an anolyte reaction occurs at a cell potential less than −1.50 V; a positive section comprising a first metal electrode in contact with the electroactive redox molecule and a supporting electrolyte dissolved in a solvent; and a negative section comprising a second metal electrode in contact with the electroactive redox molecule and additional electrolyte dissolved in additional solvent.

2 . The system of claim 1 , wherein the anolyte moiety comprises at least one anolyte moiety selected from the group consisting of phenothiazine sulfone, dibenzothiophene sulfone, disulfones of thianthrene, and any combinations thereof.

3 . The system of claim 1 or claim 2 , wherein the electroactive redox molecule comprises at least two reversible redox reactions corresponding to an electrochemical unit cell potential greater than or equal to 3.0 V.

4 . The system of any one of claims 1-3 , wherein the electroactive redox molecule with the at least two reversible redox reactions comprises at least one electroactive redox molecule selected from the group consisting of phenothiazine-5,5-dioxide, thianthrene S-dioxide, and any combinations thereof and has an electrochemical unit cell potential greater than or equal to 3 V.

5 . The system of any one of claims 1-4 , wherein the electroactive redox molecule is dispersed as a non-fluid suspension or emulsion in a polar aprotic fluid, wherein the polar aprotic fluid comprises at least one polar aprotic fluid selected from the group consisting of acetonitrile, dimethoxyethane, dimethylsulfoxide, dimethylacetamide, N,N-dimethylformamide, ethylene carbonate, propylene carbonate, nitromethane, propyl sulfone, butyl sulfone, propionitrile, valeronitrile, glutaronitrile, gamma-valerolactone, gamma-butyrolactone and sulfolane, and any combination thereof.

6 . The system of any one of claims 1-5 , wherein a concentration of the electroactive redox molecule is at least 0.5 moles per liter of a dispersed fluid phase.

7 . The system of any one of claims 1-6 , wherein the positive section is separated from the negative section by a porous separator and/or an ion-selective membrane, and wherein the system further comprises:
a circulation device configured to circulate a catholyte or an anolyte from a storage tank to the positive section or the negative section, mechanisms to provide flow of an inert gas, wherein the flow of inert gas flow forms a purge gas stream, wherein the inert gas flow comprises nitrogen or a noble gas, and mechanisms to condense solvent vapor from the purge gas stream and reintroduce the condensed solvent into a recirculating fluid loop comprising the electroactive redox molecule.

8 . The system of any one of claims 1-7 , further comprising from 2 to 250 electrochemical cells to form a battery stack, wherein each of the electrochemical cells comprises a corresponding positive section comprising a catholyte and a corresponding negative section comprising an anolyte moiety comprising a sulfone group in a sulfur heterocycle compound.

9 . The system of any one of claims 1-8 , wherein the positive section is separated from the negative section by a porous separator and/or an ion-selective membrane, and wherein the system further comprises a circulation device configured to circulate a catholyte or an anolyte from a storage tank to the positive section or the negative section.

10 . A composition comprising:
a symmetric electroactive redox molecule with at least 2 reversible reactions separated by at least 3.0 V, wherein the symmetric electroactive redox molecule comprises an anolyte moiety comprising a multi-ring conjugated system comprising at least one sulfone group; and a supporting electrolyte dissolved in a solvent.

11 . The composition of claim 10 , wherein the anolyte moiety comprises at least one anolyte moiety selected from the group consisting of phenothiazine sulfone, dibenzothiophene sulfone, disulfones of thianthrene, and any combinations thereof.

12 . A method for reversibly storing electrical energy in a symmetric redox flow battery with a unit cell potential equal to or greater than 3.0 V, the method comprising:
flowing a catholyte into contact with a first electrode in a positive section of the symmetric redox flow battery, wherein the catholyte comprises at least one sulfone group in a sulfur-containing heterocyclic compound, an electroactive redox molecule comprising an anolyte moiety, wherein the anolyte moiety comprises a sulfone group in a sulfur-containing heterocyclic compound, and wherein the anolyte moiety and the catholyte are present in the same cyclic system; flowing an anolyte into contact with a second metal electrode in a negative section of the symmetric redox flow battery, wherein the negative section is separated from the positive section with an ion-transporting membrane, wherein the anolyte comprises an additional portion of an organic molecule dissolved in additional solvent; and supplying electrical energy to a first metal electrode and the second metal electrode while an external load is not in electrical communication with the first metal electrode and the second metal electrode to charge the symmetric redox flow battery while flowing the catholyte and flowing the anolyte.

13 . The method of claim 12 , wherein the anolyte moiety comprises at least one anolyte moiety selected from the group consisting of phenothiazine sulfone, dibenzothiophene sulfone, disulfones of thianthrene, and any combination thereof.

14 . The method of claim 12 or claim 13 , further comprising discharging the symmetric redox flow battery by establishing electrical communication between the external load with the first metal electrode and the second metal electrode while flowing the catholyte and flowing the anolyte.

15 . A method of synthesizing a redox active sulfone from a sulfur-containing heterocycle comprising:
reacting the sulfur-containing heterocycle with an acid and an oxidizing agent to form products comprising an oxidized sulfone, wherein the oxidizing agent comprises at least one oxidizing agent selected from the group consisting of aqueous hydrogen peroxide, oxygen, ozone, oxones, potassium chlorate, potassium perchlorate, peroxydisulfuring acid, peroxymonosulfuric acid, hypochlorite, chlorite, chlorate, perchlorate and other halogen analogs, perborates, permanganate, chromate, dichromate or nitric acid, cerium (IV) containing compounds, chromium (VI) containing compounds, vanadium (V) containing compounds, an iron (VI) containing compound, and any combinations thereof; and separating the products from unreacted portions of the acid and the oxidizing agent, wherein the products comprising the oxidized sulfone is a redox-active molecule with at least one electrochemically reversible reaction at a cell potential less than −1.5 V.

16 . The method of claim 15 , wherein the sulfur-containing heterocycle comprises a phenothiazine moiety and the products have two reversible electrochemical reactions separated by a cell potential greater than or equal to 3.0 V.

17 . The method of claim 15 or claim 16 , wherein the redox active sulfone has at least one electrochemically reversible reaction at a cell potential less than −2.5 V.

18 . The method of any one of claims 15-17 , wherein the redox active sulfone comprises a dibenzothiophene sulfone moiety.

Assignees

• Exxonmobil Technology & Engineering Company

Inventors

• Bodige Satish
• Desai Divyaraj
• Metz Jordan
• Mabon Ross
• Elsen Heather A

Classifications

• H01M2300/0017

  Non-aqueous electrolytes · CPC title

• H01M2300/0002

  Aqueous electrolytes · CPC title

• H01M8/188 Primary

  by recharging of redox couples containing fluids; Redox flow type batteries · CPC title

• Y02E60/50

  Fuel cells · CPC title