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

US11329304B2 · kind B2 · utility

Assignees

• The Regents of the University of California · US
• The Board of Trustees of the University of Illinois · US

Inventors

• Brett A. Helms · Oakland, US
• Sean E. Doris · San Francisco, US
• Ashleigh Ward · Berkeley, US
• Peter D. Frischmann · Berkeley, US
• Etienne Chenard · Urbana, US
• Nagarjuna Gavvalapalli · Urbana, US
• Jeffrey S. Moore · Savoy, US

Key dates

• Filing date: May 26, 2017
• Grant date: May 10, 2022
• Expiry date: May 26, 2037

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y02E60/50
• WIPO field: Electrical machinery, apparatus, energy
• WIPO sector: Electrical engineering

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 importan…