Redox-flow batteries employing oligomeric organic active materials and size-selective microporous polymer membranes

Patent metadata

Field	Value
Publication number	US-11329304-B2
Application number	US-201715606961-A
Country	US
Kind code	B2
Filing date	May 26, 2017
Priority date	May 27, 2016
Publication date	May 10, 2022
Grant date	May 10, 2022

Abstract

Intermittent energy sources, including solar and wind, require scalable, low-cost, multi-hour energy storage solutions to be effectively incorporated into the grid. Redox-flow batteries offer a solution, but suffer from rapid capacity fade and low Coulombic efficiency due to the high permeability of redox-active species across the battery's membrane. Here we show that active-species crossover can be arrested by scaling the membrane's pore size to molecular dimensions and in turn increasing the size of the active material to be above the membrane's pore-size exclusion limit. When oligomeric redox-active organic molecules were paired with microporous polymer membranes, the rate of active-material crossover was either completely blocked or slowed more than 9,000-fold compared to traditional separators at minimal cost to ionic conductivity. In the case of the latter, this corresponds to an absolute rate of ROM crossover of less than 3 μmol cm−2 day−1 (for a 1.0 M concentration gradient), which exceeds performance targets recently set forth by the battery industry. This strategy was generalizable to both high and low-potential ROMs in a variety of electrolytes, highlighting the importance of macromolecular design in implementing next-generation redox-flow batteries.

First claim

What is claimed is:

1. A redox flow cell comprising:
at least one redox active oligomer (RAO) comprising: at least two redox active organic molecules, chosen from nitroxide radicals, nitronylnitroxide radicals, thiazyl radicals, thiafulvalenes, thioethers, thiolanes, thiophenes, viologens, tetraketopiperazines, quinoxalines, triarylamines, diarylalkylamines, quinones, anthraquinones, metallocenes, carbazoles, N-alkylated 4-acylpyridiniums, N-alkylated 4-benzoylpyridiniums, 1,4-dialkoxyl-2,5-dialkylbenzenes, 1,2,3-(dialkylamino)cyclopropeniums, benzofurazans, benzothiadiazoles, nitrobenzenes, and isomers and derivatives thereof; and a chemical scaffold to which the redox active organic molecules are covalently bound, chosen from aliphatic hydrocarbons, cyclic aliphatic hydrocarbons, aromatic hydrocarbons, polycyclic aromatic hydrocarbons, alkylene glycols, alkylene imines, quaternary alkylene iminiums, aliphatic esters, aromatic esters, aliphatic ethers, aromatic ethers, aliphatic thioethers, aromatic thioethers, aliphatic amides, aromatic amides, aliphatic sulfones, aromatic sulfones, and combinations and derivatives thereof; wherein the RAO comprises one structure selected from the group consisting of

an electrolyte; and
a microporous membrane having a thickness of from 5 to 500 microns comprising: a polymer of intrinsic microporosity (PIM) crosslinked with a crosslinking agent having a pore size less than 1.2 nm.

2. The redox flow cell of claim 1 wherein the undiluted RAO is a liquid.

3. The redox flow cell of claim 1 wherein the undiluted RAO is an ionic compound.

4. The redox flow cell of claim 1 wherein the RAO is a N-ethyl-4,4′-bipyridinium hexafluorophosphate, viologen dimer, viologen trimer, acylpyridinium trimer, or

(DB3 trimer).

5. The redox flow cell of claim 1 wherein the RAO is a polydisperse chemical compound comprising: at least two redox active organic molecules, chosen from nitroxide radicals, nitronylnitroxide radicals, thiazyl radicals, thiafulvalenes, thioethers, thiolanes, thiophenes, viologens, tetraketopiperazines, quinoxalines, triarylamines, diarylalkylamines, quinones, anthraquinones, metallocenes, carbazoles, N-alkylated 4-acylpyridiniums, N-alkylated 4-benzoylpyridiniums, 1,4-dialkoxyl-2,5-dialkylbenzenes, 1,2,3-(dialkylamino)cyclopropeniums, benzofurazans, benzothiadiazoles, nitrobenzenes, and isomers and derivatives thereof; and a chemical scaffold to which the redox active organic molecules are covalently bound, chosen from aliphatic hydrocarbons, cyclic aliphatic hydrocarbons, aromatic hydrocarbons, polycyclic aromatic hydrocarbons, alkylene glycols, alkylene imines, quaternary alkylene iminiums, aliphatic esters, aromatic esters, aliphatic ethers, aromatic ethers, aliphatic thioethers, aromatic thioethers, aliphatic amides, aromatic amides, aliphatic sulfones, aromatic sulfones, and combinations and derivatives thereof.

6. The chemical scaffold in claim 4 or claim 5 , to which the redox active organic molecules are covalently bound to form a RAO, is linear.

7. The chemical scaffold in claim 4 or claim 5 , to which the redox active organic molecules are covalently bound to form a RAO, is branched.

8. The redox flow cell of claim 4 or claim 5 , to which the redox active organic molecules are covalently bound to form a RAO, is cyclic.

9. The redox flow cell of claim 1 wherein the RAO is an ionic compound and used undiluted, or as a solution, dispersion, or suspension in water or an organic solvent.

10. The redox flow cell of claim 1 wherein the RAO is used as a solution, dispersion, or suspension in an aqueous or an organic electrolyte.

11. The redox flow cell of claim 1 wherein the electrolyte is an aqueous or organic solution containing at least one dissolved salt.

12. The redox flow cell of claim 1 wherein the microporous membrane comprises a polymer of intrinsic microporosity (PIM) having a pore size less than 1.2 nm.

13. The redox flow cell of claim 1 wherein the microporous membrane is an unsupported membrane (5 to 500 microns in thickness).

14. The redox flow cell of claim 1 comprising a porous organic or inorganic support coated on a single side or on both sides with the microporous membrane.

15. The redox flow cell of claim 1 wherein the microporous membrane reduces the diffusive permeability and rate of crossover of the RAO between the electrode compartments in the redox flow cell.

16. The redox flow cell of claim 1 wherein the microporous membrane blocks the diffusive permeability and crossover of the RAO between the electrode compartments in the redox flow cell.

17. The redox flow cell of claim 1 , wherein the microporous membrane has a pore size of less than 1 nm.

18. The redox flow cell of claim 1 wherein the polymer of intrinsic microporosity (PIM) crosslinked with a 0.1 molar equivalent of the crosslinking agent.

19. The redox flow cell of claim 18 wherein crosslinking agent comprises an azide group which has been converted into a reactive nitrene and is inserted into the a C—H bond of the polymer.

20. The redox flow cell of claim 19 wherein crosslinking agent is 2,6-bis(4-azidobenzylidene)-cyclohexanone.

21. The redox flow cell of claim 1 wherein the RAO has a molecular dimension of at least 8.8 Å.

22. The redox flow cell of claim 21 wherein the RAO has a molecular dimension of from 8.8 Å to 16.8 Å.

23. The redox flow cell of claim 21 wherein the RAO has a molecular dimension of at least 12.3 Å.

24. The redox flow cell of claim 23 wherein the RAO has a molecular dimension of from 12.3 Å to 16.8 Å.

Assignees

• Univ California
• Univ Illinois

Inventors

• Helms Brett A
• Doris Sean E
• Ward Ashleigh L
• Frischmann Peter D
• Chenard Etienne
• Gavvalapalli Nagarjuna
• Moore Jeffrey S

Classifications

• H01M8/188 Primary

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

• Y02E60/50

  Fuel cells · CPC title