# US 2015/0147673 A1 · High-Energy-Density, Aqueous, Metal-Polyiodide Redox Flow Batteries

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- Number: US 2015/0147673 A1
- Document ID: US20150147673A1
- Status: Published application
- Kind: A1
- Application number: 14/089,499
- Filed: 2013-11-25
- Published: 2015-05-28
- Earliest claimed: 2013-11-25
- Assignees: Battelle Memorial Institute
- Applicants: Battelle Memorial Institute
- Inventors: Bin Li; Zimin Nie; Wei Wang; Jun Liu; Vincent L. Sprenkle
- Web page: https://patentgrep.com/patent/US20150147673A1

## CPC

- H01M 8/188: {by recharging of redox couples containing fluids; Redox flow type batteries}
- H01M 8/20: Indirect fuel cells, e.g. fuel cells with redox couple being irreversible (H01M8/18 takes precedence)
- 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

Improved metal-based redox flow batteries (RFBs) can utilize a metal and a divalent cation of the metal (M2+) as an active redox couple for a first electrode and electrolyte, respectively, in a first half-cell. For example, the metal can be Zn. The RFBs can also utilize a second electrolyte having I−, anions of Ix (for x≧3), or both in an aqueous solution, wherein the I− and the anions of Ix (for x≧3) compose an active redox couple in a second half-cell.

## Claims

### Claim 1

A redox flow battery (RFB) comprising:
a first electrolyte comprising divalent cations of a metal (M2+) in an aqueous solution and a first electrode comprising the metal (M), wherein M and M2+ compose a first active redox couple at a first half-cell;
a second electrolyte comprising I−, anions of Ix (x≧3), or both in the aqueous solution, wherein I− and anions of Ix compose a second active redox couple at a second half-cell; and
a membrane or separator between the first and second half-cells.

### Claim 2 (depends on 1)

The RFB of claim 1, wherein the metal comprises an element selected from the group consisting of Ga, Fe, Cr, Ti, and combinations thereof.

### Claim 3 (depends on 1)

The RFB of claim 1, wherein the metal comprises Zn.

### Claim 4 (depends on 1)

The RFB of claim 1, wherein the aqueous solution has a pH greater than 3.

### Claim 5 (depends on 1)

The RFB of claim 1, wherein the first electrode comprises the metal (M) on a porous, conductive material.

### Claim 6 (depends on 5)

The RFB of claim 5, wherein the porous conductive material comprises conductive carbon.

### Claim 7 (depends on 5)

The RFB of claim 5, wherein the porous conductive material comprises graphite fibers.

### Claim 8 (depends on 5)

The RFB of claim 5, wherein the porous conductive material comprises graphene.

### Claim 9 (depends on 5)

The RFB of claim 5, wherein the porous conductive material comprises a metallic material.

### Claim 10 (depends on 1)

The RFB of claim 1, wherein the first electrode comprises M on a dense solid conductive material.

### Claim 11 (depends on 10)

The RFB of claim 10, wherein the dense solid conductive material comprises a metallic material.

### Claim 12 (depends on 10)

The RFB of claim 10, wherein the dense solid conductive material comprises conductive carbon materials.

### Claim 13 (depends on 1)

The RFB of claim 1, wherein the membrane comprises an ion-exchange membrane.

### Claim 14 (depends on 1)

The RFB of claim 1, wherein the membrane comprises a solid-state membrane.

### Claim 15 (depends on 1)

The RFB of claim 1, wherein the separator comprises a microporous separator.

### Claim 16 (depends on 1)

The RFB of claim 1, wherein the aqueous solution contains substantially no iodine.

### Claim 17 (depends on 1)

The RFB of claim 1, wherein the anions of Ix comprise I3−.

### Claim 18 (depends on 1)

The RFB of claim 1, wherein the anions of Ix comprise I4−.

### Claim 19 (depends on 1)

The RFB of claim 1, wherein the anions of Ix comprise I6−.

### Claim 20 (depends on 1)

The RFB of claim 1, wherein the anions of Ix comprise I2n+p−, wherein n and p are positive integers and 1≧p≧4.

### Claim 21 (depends on 1)

The RFB of claim 1, having an energy density (based on the positive electrolyte) greater than 60 Wh/L.

### Claim 22 (depends on 1)

The RFB of claim 1, further comprising a conduit connecting the first and second half-cells and a flow controller, wherein electrolyte from the second half-cell can circulate through the conduit to the first half-cell to react with the Zn and wherein the flow controller permits or restricts circulation through the conduit.

### Claim 23

A redox flow battery (RFB) comprising:
a first electrolyte comprising Zn2+ in an aqueous solution and a first electrode comprising Zn, wherein the Zn and the Zn2+ compose a first active redox couple at a first half-cell;
a second electrolyte comprising I−, anions of Ix (x≧3), or both in the aqueous solution, wherein the I− and the anions of Ix compose a second active redox couple at a second half-cell; and
a membrane or separator between the first and second half-cells;
wherein the RFB has an energy density (based on the positive electrolyte) greater than 60 Wh/L and the aqueous solution contains substantially no iodine.

### Claim 24 (depends on 23)

The RFB of claim 23, wherein the aqueous solution has a pH greater than 3.

### Claim 25 (depends on 23)

The RFB of claim 23, further comprising a conduit connecting the first and second half-cells and a flow controller, wherein electrolyte from the second half-cell can circulate through the conduit to the first half-cell to react with the Zn and wherein the flow controller permits or restricts circulation through the conduit.

### Claim 26

A method for storing electrical energy in a RFB, the method comprising:
Providing an electrical source of energy to the RFB;
Reducing a M2+ electroactive species thereby electrodepositing M on an electrode in a first half-cell, wherein M2+ is a divalent cation of a metal, M;
Oxidizing a positive electroactive species, I−, to yield one or more anions of Ix (x≧3) in a second half-cell; and
Ceasing the electrical source of energy to prevent formation of iodine.

### Claim 27 (depends on 26)

The method of claim 26, wherein the anions of Ix comprise I3−.

### Claim 28 (depends on 26)

The method of claim 26, wherein the anions of Ix comprise I4−.

### Claim 29 (depends on 26)

The method of claim 26, wherein the anions of Ix comprise I6−.

### Claim 30 (depends on 26)

The method of claim 26, wherein the anions of Ix comprise I2n+p−, wherein n and p are positive integers and 1≦p≦4.

### Claim 31 (depends on 26)

The method of claim 26, wherein the metal is Zn.

### Claim 32 (depends on 26)

The method of claim 26, further comprising yielding an energy density (based on the positive electrolyte) greater than 60 Wh/L.