# US 8,771,856 B2 · Fe-V redox flow batteries > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,771,856 B2 - Document ID: US8771856B2 - Status: Granted - Kind: B2 - Application number: 12/892,698 - Filed: 2010-09-28 - Published: 2012-03-29 - Granted: 2014-07-08 - Earliest claimed: 2010-09-28 - Assignees: Battelle Memorial Institute - Applicants: Liyu Li; Soowhan Kim; Zhenguo Yang; Wei Wang; Jianlu Zhang; Baowei Chen; Zimin Nie; Guanguang Xia - Inventors: Liyu Li; Soowhan Kim; Zhenguo Yang; Wei Wang; Jianlu Zhang; Baowei Chen; Zimin Nie; Guanguang Xia - Web page: https://patentgrep.com/patent/US8771856B2 ## CPC - H01M 8/184: {Regeneration by electrochemical means} - 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) - H01M 50/426: Fluorocarbon polymers - H01M 2300/0005: Acid electrolytes - H01M 2300/0011: Sulfuric acid-based - 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 having a supporting solution that includes Cl− anions is characterized by an anolyte having V2+ and V3+ in the supporting solution, a catholyte having Fe2+ and Fe3+ in the supporting solution, and a membrane separating the anolyte and the catholyte. The anolyte and catholyte can have V cations and Fe cations, respectively, or the anolyte and catholyte can each contain both V and Fe cations in a mixture. Furthermore, the supporting solution can contain a mixture of SO42− and Cl− anions. ## Claims ### Claim 1 A redox flow battery system having: A membrane separating an anolyte and a catholyte; the anolyte comprising V2+ and V3+ in a negative supporting solution comprising an initial concentration of at least 0.5M Fe cations and Cl− anions; the catholyte comprising Fe2+ and Fe3+ in a positive supporting solution comprising an initial concentration of at least 0.5M V cations and Cl− anions; wherein the initial concentration of Fe cations in the negative supporting solution is substantially equal to the initial concentration of V cations in the positive supporting solution. ### Claim 2 (depends on 1) The system of claim 1, wherein the Fe2+ and Fe3+ concentrations are greater than 0.5 M. ### Claim 3 (depends on 1) The system of claim 1, wherein the V2+ and V3+ concentrations are greater than 0.5M. ### Claim 4 (depends on 1) The system of claim 1, wherein the membrane is a hydrocarbon-based membrane. ### Claim 5 (depends on 1) The system of claim 1, wherein the membrane is a micro-porous separator. ### Claim 6 (depends on 1) The system of claim 1, wherein the membrane is not a sulfonated tetrafluoroethylene based fluoropolymer-copolymer. ### Claim 7 (depends on 1) The system of claim 1, further comprising negative and positive electrodes in contact with the anolyte and the catholyte, respectively, wherein the electrodes do not contain a redox catalyst. ### Claim 8 (depends on 1) The system of claim 1, having a cell temperature less than 60° C. during operation. ### Claim 9 (depends on 1) The system of claim 1, having a cell temperature between −20° C. and 50° C. during operation. ### Claim 10 (depends on 1) The system of claim 1, wherein the positive supporting solution, the negative supporting solution, or both further comprises SO42− anions. ### Claim 11 (depends on 10) The system of claim 10, wherein the Cl− to SO42− concentration ratio is between 1:100 and 100:1. ### Claim 12 (depends on 10) The system of claim 10, wherein the Cl− to SO42− concentration ratio is between 1:10 and 10:1. ### Claim 13 (depends on 10) The system of claim 10, wherein the Cl− and SO42− concentration ratio is between 1:3 and 3:1. ### Claim 14 (depends on 12) The system of claim 12, wherein concentrations of V2+, V3+, Fe2+, and Fe3+ are greater than 1M in the anolyte and in the catholyte. ### Claim 15 (depends on 10) The system of claim 10, wherein concentrations of V2+ and V3+ are greater than 1.5M in the anolyte and concentrations of Fe2+ and Fe3+ are greater than 1.5M in the catholyte. ### Claim 16 (depends on 1) The system of claim 1, wherein said cations of V have a concentration greater than 0.5 M in the positive supporting solution and said cations of Fe have a concentration greater than 0.5 M in the negative supporting solution. ### Claim 17 (depends on 1) The system of claim 1, having a catholyte side of the membrane and an anolyte side of the membrane, wherein the catholyte side of the membrane has a total concentration of Fe and V that is substantially equal to that of the anolyte side of the membrane. ### Claim 18 A redox flow battery system comprising: A membrane separating an anolyte and a catholyte the anolyte comprising a total concentration of V2+ and V3+ cations greater than 0.5 M in a an initial negative supporting solution comprising Cl− anions and greater than a 0.5 M concentration of Fe cations; the catholyte comprising a total concentration of Fe2+ and Fe3+ cations greater than 0.5 M in a an initial positive supporting solution comprising Cl− anions and greater than a 0.5 M concentration of V cations.