# US 2018/0323484 A1 · Additives for a flow battery

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- Number: US 2018/0323484 A1
- Document ID: US20180323484A1
- Status: Published application
- Kind: A1
- Application number: 15/773,670
- Filed: 2016-11-07
- Published: 2018-11-08
- Earliest claimed: 2015-11-10
- Assignees: Bromine Compounds Ltd.
- Applicants: Bromine Compounds Ltd.
- Inventors: Ben-Zion MAGNES; Neta COHEN; Iris BEN-DAVID; Ronny COSTI
- Web page: https://patentgrep.com/patent/US20180323484A1

## CPC

- H01M 12/085: {Zinc-halogen cells or batteries}
- H01M 4/86: Inert electrodes with catalytic activity, e.g. for fuel cells
- H01M 8/188: {by recharging of redox couples containing fluids; Redox flow type batteries}
- H01M 10/365: {Zinc-halogen accumulators}
- H01M 2300/0002: Aqueous electrolytes
- Y02E 60/10: Energy storage using batteries
- 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

The invention relates to an electrolyte solution suitable for use in a zinc-bromine battery, comprising zinc bromide and a mixture of at least two complexing agents selected from the group consisting of 1-R2-2-methyl pyridinium bromide and 1-R3-3-methyl pyridinium bromide salts, wherein each of R2 and R3 is independently an alkyl group having not less than five carbon atoms.

## Claims

### Claim 1

1) An electrolyte solution suitable for use in a zinc-bromine battery, comprising zinc bromide and a mixture of at least two complexing agents selected from the group consisting of 1-R2-2-methyl pyridinium bromide and 1-R3-3-methyl pyridinium bromide salts, wherein each of R2 and R3 is independently an alkyl group having not less than five carbon atoms.

### Claim 2 (depends on 1)

2) An electrolyte solution according to claim 1, wherein R2 and R3 are independently selected from the group consisting of C5, C7 and C8 normal and branched alkyl groups.

### Claim 3 (depends on 2)

3) An electrolyte solution according to claim 2, wherein at least one of R2 and R3 is C5 alkyl group.

### Claim 4 (depends on 1)

4) An electrolyte solution according to claim 1, wherein the mixture comprises two complexing agents selected from the group consisting of 1-R2-2-methyl pyridinium bromide and 1-R3-3-methyl pyridinium bromide salts, wherein the molar ratio between the components of the mixture is in the range from 1:5 to 5:1.

### Claim 5 (depends on 3)

5) An electrolyte solution according to claim 3, comprising 1-n-pentyl-2-methyl pyridinium bromide (2-MPePy) and 1-n-pentyl-3-methyl pyridinium bromide (3-MPePy).

### Claim 6 (depends on 3)

6) An electrolyte solution according to claim 3, comprising 1-n-pentyl-2-methyl pyridinium bromide (2-MPePy) and 1-isopentyl-3-methyl pyridinium bromide (3-MiPePy).

### Claim 7 (depends on 3)

7) An electrolyte solution according to claim 3, comprising 1-n-pentyl-3-methyl pyridinium bromide (3-MPePy) and 1-isopentyl-3-methyl pyridinium bromide (3-MiPePy).

### Claim 8 (depends on 1)

8) An electrolyte solution according to claim 1, which further comprises tetraalkyl ammonium halide salt.

### Claim 9 (depends on 8)

9) An electrolyte solution according to claim 8, comprising 1-R2-2-methyl pyridinium bromide, 1-R3-3-methyl pyridinium bromide and a tetraalkyl ammonium salt.

### Claim 10 (depends on 9)

10) An electrolyte solution according to claim 9, wherein R2 is C5 straight or branched alkyl; R3 is C7-C8 straight or branched alkyl; and the tetraalkyl ammonium salt is selected from the group consisting of tetraethyl ammonium bromide and tetrabutyl ammonium bromide.

### Claim 11 (depends on 10)

11) An electrolyte solution according to claim 10, comprising 1-n-pentyl-2-methyl pyridinium bromide, 1-iso-octyl-3-methyl pyridinium bromide and tetraethyl ammonium bromide.

### Claim 12 (depends on 8)

12) An electrolyte solution according to claim 8, comprising a first 1-R3-3-methyl pyridinium bromide, a second 1-R3-3-methyl pyridinium bromide and a tetraalkyl ammonium salt.

### Claim 13 (depends on 12)

13) An electrolyte solution according to claim 12, wherein the first R3 is C5 straight or branched alkyl and the second R3 is C7-C8 straight or branched alkyl.

### Claim 14 (depends on 13)

14) An electrolyte solution according to claim 13, comprising 1-n-pentyl-3-methyl pyridinium bromide, 1-iso-octyl-3-methyl pyridinium bromide and tetrabutyl ammonium bromide.

### Claim 15

15) Use of a mixture comprising at least two complexing agents selected from the group consisting of 1-R2-2-methyl pyridinium bromide and 1-R3-3-methyl pyridinium bromide salts, wherein each of R2 and R3 is independently an alkyl group having not less than five carbon atoms, as an additive in the electrolyte solution of zinc bromine flow cells operating at a temperature above 35° C.

### Claim 16 (depends on 15)

16) Use according to claim 15, wherein the mixture of complexing agents used as an additive in an electrolyte solution suitable for use in a zinc-bromine battery, comprising zinc bromide and a mixture of at least two complexing agents selected from the group consisting of 1-R2-2-methyl pyridinium bromide and 1-R3-3-methyl pyridinium bromide salts, wherein R2 and R3 are independently selected from the group consisting of C5, C7 and C8 normal and branched alkyl groups.

### Claim 17

17) A method of operating a zinc-bromine battery, comprising adding to the electrolyte of said battery a mixture of at least two complexing agents selected from the group consisting of 1-R2-2-methyl pyridinium bromide and 1-R3-3-methyl pyridinium bromide salts, wherein each of R2 and R3 is independently an alkyl group having not less than five carbon atoms, and charging or discharging said cell at a temperature above 35° C.

### Claim 18 (depends on 17)

18) A method of operating a zinc-bromine battery according to claim 17, wherein the mixture of complexing agents is an electrolyte solution suitable for use in a zinc-bromine battery, comprising zinc bromide and a mixture of at least two complexing agents selected from the group consisting of 1-R2-2-methyl pyridinium bromide and 1-R3-3-methyl pyridinium bromide salts, wherein R2 and R3 are independently selected from the group consisting of C5, C7 and C8 normal and branched alkyl groups.