Aqueous electrolytes for redox flow battery systems

Patent metadata

Field	Value
Publication number	US-9793566-B2
Application number	US-201514690224-A
Country	US
Kind code	B2
Filing date	Apr 17, 2015
Priority date	Apr 17, 2015
Publication date	Oct 17, 2017
Grant date	Oct 17, 2017

Abstract

An aqueous redox flow battery system includes an aqueous catholyte and an aqueous anolyte. The aqueous catholyte may comprise (i) an optionally substituted thiourea or a nitroxyl radical compound and (ii) a catholyte aqueous supporting solution. The aqueous anolyte may comprise (i) metal cations or a viologen compound and (ii) an anolyte aqueous supporting solution. The catholyte aqueous supporting solution and the anolyte aqueous supporting solution independently may comprise (i) a proton source, (ii) a halide source, or (iii) a proton source and a halide source.

First claim

We claim:

1. An aqueous catholyte for use in a redox flow battery system, comprising:
a catholyte aqueous supporting solution; and
an electrochemically active component comprising
(i) a monosubstituted, disubstituted, trisubstituted, or tetrasubstituted thiourea having a general formula I

wherein R 1 -R 4 independently are hydrogen, aliphatic, substituted aliphatic, alkoxy, substituted alkoxy, acyl, substituted acyl, aryl, substituted aryl, arylalkyl, substituted arylalkyl, alkylaryl, or substituted alkylaryl, the optionally substituted thiourea having a concentration sufficient to charge a redox flow battery system when the optionally substituted thiourea is oxidized, and/or

(ii) a water-soluble nitroxyl radical compound having a general formula II

wherein n is 0, 1, or 2,
R 5 -R 6 and R 9 -R 14 independently are hydrogen, aliphatic, substituted aliphatic, halo, hydroxyl, carboxyl, amino, cyano, or thiol, and
each R 7 and R 8 independently is hydrogen, optionally substituted aliphatic, halo, hydroxyl, carboxyl, amino, cyano, or thiol, the water-soluble nitroxyl radical compound having a concentration sufficient to charge a redox flow battery system when the water-soluble nitroxyl radical compound is oxidized.

2. The aqueous catholyte of claim 1 , wherein the monosubstituted, disubstituted, trisubstituted, or tetrasubstituted thiourea is an alkyl-substituted thiourea.

3. The aqueous catholyte of claim 1 , wherein the monosubstituted, disubstituted, trisubstituted, or tetrasubstituted thiourea is N-methyl thiourea, N,N′-dimethyl thiourea, N-ethyl thiourea, N,N′-diethyl thiourea, tetramethyl thiourea, tetraethyl thiourea, or any combination thereof.

4. The aqueous catholyte of claim 1 , wherein:
R 5 , R 6 and R 11 -R 14 independently are hydrogen or C 1 -C 10 alkyl;
each R 7 and R 8 independently is hydrogen or C 1 -C 10 alkyl; and
at least one of R 9 and R 10 is other than hydrogen.

5. The aqueous catholyte of claim 1 , wherein:
R 5 , R 6 , R 13 , and R 14 are independently C 1 -C 10 alkyl;
R 7 , R 8 , R 11 , and R 12 are hydrogen; and
at least one of R 9 and R 10 is hydroxyl, amino, carboxyl, or cyano.

6. The aqueous catholyte of claim 1 , wherein the water-soluble nitroxyl radical compound is:

or any combination thereof.

7. The aqueous catholyte of claim 1 , wherein the catholyte, prior to charging, has a concentration of the monosubstituted, disubstituted, trisubstituted, or tetrasubstituted thiourea within a range of 0.05 M to 5 M and/or a concentration of the water-soluble nitroxyl radical compound within a range of 1 mM to 5 M.

8. The aqueous catholyte of claim 1 , wherein the catholyte aqueous supporting solution comprises a binary acid, an alkali metal halide, or a combination thereof.

9. The aqueous catholyte of claim 1 , wherein the catholyte aqueous supporting solution comprises a halide (X − ) source, and [X − ]≧[electrochemically active component].

10. The aqueous catholyte of claim 1 , wherein:
the catholyte aqueous supporting solution comprises (i) a proton source, (ii) a halide source, or (iii) a proton source and a halide source.

11. An aqueous electrolyte system for use in a redox flow battery system, comprising:
an aqueous catholyte according to claim 1 ;
an aqueous anolyte.

12. The aqueous electrolyte system of claim 11 , wherein the aqueous anolyte comprises:
an anolyte aqueous supporting solution; and
metal cations or a viologen compound comprising cations having a general formula

wherein R 15 is aliphatic, substituted aliphatic, aryl, substituted aryl, arylalkyl, or substituted arylalkyl.

13. The aqueous electrolyte system of claim 12 , wherein:
the anolyte comprises metal cations, and each of the anolyte aqueous supporting solution and the aqueous catholyte supporting solution independently comprises (i) a proton source, (ii) a halide source, or (iii) a proton source and a halide source; or
the anolyte comprises the viologen compound, and each of the aqueous anolyte supporting solution and the aqueous catholyte supporting solution independently comprises a non-acidic halide source.

14. A redox flow battery system, comprising:
the aqueous electrolyte system of claim 11 ; and
an ion-exchange membrane or porous separator.

15. The redox flow battery system of claim 14 , wherein when the redox flow battery system is at least partially charged:
the catholyte comprises a redox pair consisting of (i) the monosubstituted, disubstituted, trisubstituted, or tetrasubstituted thiourea and corresponding formamidinium disulfide cations, or (ii) the water-soluble nitroxyl radical compound and corresponding nitroxyl compound cations; and
the anolyte comprises (a) a metal redox pair comprising the metal cations or (b) a viologen redox pair consisting of +2 and +1 viologen cations.

16. The redox flow battery system of claim 14 , wherein when the redox flow battery system is at least partially charged, the catholyte consists essentially of:
(a) the monosubstituted, disubstituted, trisubstituted, or tetrasubstituted thiourea and corresponding formamidinium disulfide cations, and the aqueous catholyte supporting solution, wherein the aqueous catholyte supporting solution consists essentially of (i) water and (ii) the proton source, the halide source, or both the proton source and the halide source; or
(b) the water-soluble nitroxyl radical compound and corresponding nitroxyl compound cations, and the aqueous catholyte supporting solution, wherein the aqueous catholyte supporting solution consists essentially of (i) water and (ii) the proton source, the halide source, or both the proton source and the halide source.

17. An aqueous catholyte for use in a redox flow battery system, comprising an electrochemically active component and a catholyte aqueous supporting solution, wherein:
(i) the electrochemically active component is an optionally substituted thiourea having a general formula I

wherein R 1 -R 4 independently are hydrogen, aliphatic, substituted aliphatic, alkoxy, substituted alkoxy, acyl, substituted acyl, aryl, substituted aryl, arylalkyl, substituted arylalkyl, alkylaryl, or substituted alkylaryl, the optionally substituted thiourea having a concentration sufficient to charge a redox flow battery system when the optionally substituted thiourea is oxidized, and the catholyte aqueous supporting solution comprises NaCl, KCl, HCl, or a combination thereof; or

(ii) the electrochemically active component is a water-soluble nitroxyl radical compound, and the catholyte aqueous supporting solution comprises NaCl, KCl, or a combination thereof.

18. An aqueous catholyte for use in a redox flow battery system, wherein, prior to charging, the catholyte consists essentially of an electrochemically active component and a catholyte aqueous supporting solution, wherein:
(i) the electrochemically active component is an

Assignees

• Battelle Memorial Institute

Inventors

• Liu Tianbiao
• Li Bin
• Wei Xiaoliang
• Nie Zimin
• Wang Wei
• Liu Jun
• Sprenkle Vincent L

Classifications

• H01M2300/0002

  Aqueous electrolytes · CPC title

• H01M8/188 Primary

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

• H01M8/20

  Indirect fuel cells, e.g. fuel cells with redox couple being irreversible (H01M8/18 takes precedence) · CPC title

• Y02E60/528

  Cross-Sectional Technologies · mapped topic

• Y02E60/50

  Fuel cells · CPC title