Redox-flow batteries employing oligomeric organic active materials and size-selective microporous polymer membranes
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.
- Research Organization:
- Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States); Univ. of Illinois at Urbana-Champaign, IL (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC02-05CH11231
- Assignee:
- The Regents of the University of California (Oakland, CA); The Board of Trustees of the University of Illinois (Urbana, IL)
- Patent Number(s):
- 11,329,304
- Application Number:
- 15/606,961
- OSTI ID:
- 1892927
- Resource Relation:
- Patent File Date: 05/26/2017
- Country of Publication:
- United States
- Language:
- English
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