# US 12,183,925 B2 · Redox flow battery for storing electrical energy in underground storage means, and use thereof

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 12,183,925 B2
- Document ID: US12183925B2
- Status: Granted
- Kind: B2
- Application number: 17/297,777
- Filed: 2019-11-27
- Published: 2022-01-20
- Granted: 2024-12-31
- Earliest claimed: 2018-11-29
- Assignees: Friedrich-Schiller-Universitaet Jena
- Applicants: Friedrich-Schiller-Universitaet Jena
- Inventors: Ulrich Sigmar Schubert; Martin Hager
- Web page: https://patentgrep.com/patent/US12183925B2

## CPC

- H01M 4/60: of organic compounds
- H01M 4/368: {Liquid depolarisers}
- H01M 8/188: {by recharging of redox couples containing fluids; Redox flow type batteries}
- Y02E 60/10: Energy storage using batteries
- Y02E 60/50: Fuel cells
- H01M: PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION

## Abstract

A redox flow battery for storing electrical energy is described, comprising a reaction cell with two electrode chambers for catholyte and anolyte, each of which is connected to at least one liquid reservoir, the electrode chambers being separated by a membrane, being equipped with electrodes, and each being filled with electrolyte solutions which contain redox-active components dissolved or dispersed in an aqueous electrolyte solvent, as well as conducting salts dissolved therein and possibly further additives. A second embodiment relates to a redox flow battery for storing electrical energy, comprising a reaction cell with an electrode chamber for an electrolyte solution, which is connected to at least one liquid reservoir, the electrode chamber being equipped with a cathode and an anode, and being filled with electrolyte solution which contains redox-active components dissolved or dispersed in an aqueous electrolyte solvent, as well as conductive salts dissolved therein and possibly further additives. The redox flow cells are characterized in that the at least one liquid reservois is an underground storage means in which temperatures of at least 30° C. prevail, in that the concentration of the salts dissolved in the electrolyte solutions is at least 10% by weight, and in that the catholyte or the electrolyte solution contains selected redox-active and temperature-stable components. In the first embodiment, the anolyte contains a water-soluble redox-active component and in the second embodiment, the anolyte or the electrolyte solution contains a zinc salt.

## Claims

### Claim 1

A redox-flow-battery for storing electrical energy comprising a reaction cell with two electrode chambers for a catholyte and an anolyte, which are each connected to at least one liquid reservoir, the electrode chambers being separated by a membrane, being equipped with electrodes, and each being filled with electrolyte solutions which contain redox-active components dissolved or dispersed in an aqueous electrolyte solvent, as well as conductive salts dissolved therein and possibly further additives, characterized in that
the at least one liquid reservoir is an underground storage means in which temperatures of at least 30° C. prevail, in that
the concentration of the salts dissolved in the electrolyte solutions is at least 10% by weight, in that
the anolyte contains a water-soluble or water-dispersible redox-active component, and
that the catholyte contains at least one compound or composition selected from one of the groups b), c), or d) as redox-active component, wherein
b) is an organic compound comprising at least one redox-active residue of formula (Ia)
in combination with hydrochloric acid and/or a salt selected from the group consisting of ammonium salts with inorganic or organic anions, salts with tetrafluoroborate anions or salts of trifluoromethanesulfonic acid,
c) is an organic compound comprising at least one redox-active residue of the formula (Ib)
d) is an organic compound comprising at least one redox-active residue of the formula (Ic)
R7, R8, R9 and R10 represent alkyl or each of R7 and R8 and R9 and R10 together with the common carbon atom form a cycloaliphatic or heterocyclic residue,
Q is —O—, —S—, —NH—, —NR13a, —, —NR13aR13b+—(Anm−)1/m, —PR13a— or —SiR13aR13b—,
R11 is —O or —S,
R12 is —CH2—, —O—, —S—, —SO—, —SO2——NR13— or —N+R13R14— (Anm−)1/m,
R13, R13a, R13b and R14 independently of one another are monovalent organic residues, and
An is an m-valent anion and m is an integer of 1-4.

### Claim 2

A redox-flow-battery for storing electrical energy, comprising a reaction cell with an electrode chamber for an electrolyte solution, which is connected to at least one liquid reservoir, the electrode chamber being equipped with a cathode and an anode, the electrode chamber being filled with electrolyte solution which contains redox-active components dissolved or dispersed in an aqueous electrolyte solvent, as well as conductive salts dissolved therein and optionally further additives, characterized in that
the at least one liquid reservoir is an underground storage means in which temperatures of at least 30° C. prevail, in that
the concentration of the salts dissolved in the electrolyte solutions is at least 10% by weight, in that
anolyte contains a water-soluble or water-dispersible redox-active component, and
a catholyte contains at least one compound or composition selected from one of the groups b), c), or d) as redox-active component, wherein
b) is an organic compound comprising at least one redox-active residue of formula (Ia)
in combination with hydrochloric acid and/or a salt selected from the group consisting of ammonium salts with inorganic or organic anions, salts with tetrafluoroborate anions or salts of trifluoromethanesulfonic acid,
c) is an organic compound comprising at least one redox-active residue of the formula (Ib)
d) is an organic compound comprising at least one redox-active residue of the formula (Ic)
R7, R8, R9 and R10 represent alkyl or each of R7 and R8 and R9 and R10 together with the common carbon atom form a cycloaliphatic or heterocyclic residue,
Q is —O—, —S—, —NH—, —NR13a, —, —NR13aR13b+—(Anm−)1/m, —PR13a— or
—SiR13aR13b—,
R11 is —O or —S,
R12 is —CH2—, —O—, —S—, —SO—, —SO2——NR13— or —N+R13R14—(Anm−)1/m,
R13, R13a, R13b and R14 independently of one another are monovalent organic residues, and
An is an m-valent anion and m is an integer of 1-4.

### Claim 3 (depends on 1)

The redox-flow-battery according to claim 1, characterized in that the electrode chambers for catholyte and anolyte are separated by a semi-permeable membrane impermeable to the redox couple in the catholyte, and the anolyte contains zinc salt as a redox-active component.

### Claim 4 (depends on 2)

The redox-flow-battery according to claim 2, characterized in that the electrode chamber for catholyte and anolyte contains no membrane, and that the anolyte contains zinc salt as a redox-active component.

### Claim 5 (depends on 3)

The redox-flow-battery according to claim 3, characterized in that this contains a zinc-solid anode with the redox pair zinc (II)/zinc(0).

### Claim 6 (depends on 1)

The redox-flow-battery according to claim 1, characterized in that the temperature in the underground storage means is 30 to 90° C.

### Claim 7 (depends on 1)

The redox-flow-battery according to claim 1, characterized in that the concentration of salts dissolved in the electrolyte solutions is from 14 wt % to the saturation limit.

### Claim 8 (depends on 1)

The redox-flow-battery according to claim 1, characterized in that the state of charge of the catholyte or of the catholyte and the anolyte is less than 90%.

### Claim 9 (depends on 1)

The redox-flow-battery according to claim 1, characterized in that Anm− is selected from the group of halide ions, hydroxide ions, phosphate ions, sulfate ions, perchlorate ions, hexafluorophosphate ions or tetrafluoroborate ions.

### Claim 10 (depends on 1)

The redox-flow-battery according to claim 1, characterized in that the electrolyte solution contains a compound having at least one redox-active residue of the formulae (Ia), (Ib) or (Ic), which is covalently bonded to a polymer backbone selected from the group consisting of polymethacrylates, polyacrylates, polystyrenes, polyalkylene glycols, polyalkylene imines or polyvinyl ethers.

### Claim 11 (depends on 1)

The redox-flow-battery according to claim 1, characterized in that the electrolyte solution contains oligomers or polymers containing recurring structural units corresponding to formula (V) and optionally other structural units derived from solubility-facilitating comonomers
wherein
ME is a recurring structural unit derived from a polymerizable monomer,
BG is a bridging group,
Pip is a piperidinyl residue of formula (Ia), (Ib) or (Ic), and
r is an integer from 2 to 150.

### Claim 12 (depends on 1)

The redox-flow-battery according to claim 1, characterized in that the electrolyte solution contains a redox-active compound of formula (VIa) or (VIb)
wherein R7, R8, R9 and R10 have the meaning defined in claim 1,
q is an integer from 1 to 3,
R15 is a monovalent organic residue, which is optionally linked via an oxygen, sulfur or
nitrogen atom with the piperidinyl residue, and
R16 is —O—, —S— or a di- to tetravalent organic residue.

### Claim 13 (depends on 1, 11, 12)

The redox-flow-battery according to claim 1, characterized in that the electrolyte solution contains a redox-active compound of formula (VII), (VIII), (IX), (X) or (XI)
wherein R7, R8, R9, R10, R11, R12 and Q have the meaning defined in claim 1, ME, BG and r have the meaning defined in claim 11,
q has the meaning defined in claim 12,
R16a is a di- to tetravalent organic residue, and
t is 0 or 1.

### Claim 14 (depends on 12)

The redox-flow-battery according to claim 12, characterized in that
R15 is —O—(CsH2s)—R23, —S—(CsH2s)—R23 or —NR2—(CsH2s)—R23,
s is an integer from 2 to 4,
R2 has one of the meanings defined in clam 1,
R23 is a functional group selected from —OH, —SH, —NO3, —NO2, —CN, —OR17, —SR17, —(O—CH2—CH2)v—OR18, —(O—CH2—CH2)v—SR18, —COR18, —COO−(Katu+)1/u, —COOR18, —SO3−(Katu+)1/u, —SO3R18, —SO4−(Katu+)1/u, —SO4R18, —PO42−(Katu+)2/u, —PO4(R18)2, —PO32−(Katu+)2/u, —PO3(R18)2 or —NR19R20R21+(Anm−)1/m,
R17 is C1-C4 alkyl,
R18 is hydrogen or C1-C4 alkyl,
R19, R20 and R21 independently of one another are hydrogen or alkyl,
Kat is an u-valent cation,
An is an m-valent anion,
m and u independently of one another are integers between 1 and 4, and
v is an integer from 1 to 50.

### Claim 15 (depends on 1)

The redox-flow battery of claim 1, wherein the catholyte includes an organic compound comprises at least one redox-active residue of formula (Ia)
in combination with hydrochloric acid and/or a salt selected from the group consisting of ammonium salts with inorganic or organic anions, salts with tetrafluoroborate anions or salts of trifluoromethanesulfonic acid.

### Claim 16 (depends on 1)

The redox-flow battery of claim 1, wherein the catholyte includes an organic compound comprising at least one redox-active residue of the formula (Ib)

### Claim 17 (depends on 1)

The redox-flow battery of claim 1, wherein the catholyte includes an organic compound comprising at least one redox-active residue of the formula (Ic)