title: Macromolecular Design Strategies for Preventing Active-Material Crossover in Non-Aqueous All-Organic Redox-Flow Batteries.
abstract: Intermittent energy sources, including solar and wind, require scalable, low-cost, multi-hour energy storage solutions in order to be effectively incorporated into the grid. All-Organic non-aqueous 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 is arrested by scaling the membrane's pore size to molecular dimensions and in turn increasing the size of the active material above the membrane's pore-size exclusion limit. When oligomeric redox-active organics (RAOs) were paired with microporous polymer membranes, the rate of active-material crossover was reduced more than 9000-fold compared to traditional separators at minimal cost to ionic conductivity. This corresponds to an absolute rate of RAO crossover of less than 3 μmol cm-2day-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 RAOs in a variety of non-aqueous electrolytes, highlighting the versatility of macromolecular design in implementing next-generation redox-flow batteries.
authors.affiliation: Department of Chemistry, 419 Latimer Hall, University of California, Berkeley, Berkeley, CA, 94720, USA.
authors.forename: Sean E
authors.initials: SE
authors.lastname: Doris
authors.affiliation: Joint Center for Energy Storage Research, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA, 94720, USA.
authors.forename: Ashleigh L
authors.initials: AL
authors.lastname: Ward
authors.affiliation: Joint Center for Energy Storage Research, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA, 94720, USA.
authors.forename: Artem
authors.initials: A
authors.lastname: Baskin
authors.affiliation: Joint Center for Energy Storage Research, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA, 94720, USA.
authors.forename: Peter D
authors.initials: PD
authors.lastname: Frischmann
authors.affiliation: Joint Center for Energy Storage Research, University of Illinois at Urbana-Champaign, 505 South Matthews Avenue, Urbana, IL, 61801, USA.
authors.forename: Nagarjuna
authors.initials: N
authors.lastname: Gavvalapalli
authors.affiliation: Joint Center for Energy Storage Research, University of Illinois at Urbana-Champaign, 505 South Matthews Avenue, Urbana, IL, 61801, USA.
authors.forename: Etienne
authors.initials: E
authors.lastname: Chénard
authors.affiliation: Joint Center for Energy Storage Research, University of Michigan, 930 North University Avenue, Ann Arbor, MI, 48109, USA.
authors.forename: Christo S
authors.initials: CS
authors.lastname: Sevov
authors.affiliation: Joint Center for Energy Storage Research, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA, 94720, USA.|The Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA, 94720, USA.
authors.forename: David
authors.initials: D
authors.lastname: Prendergast
authors.affiliation: Joint Center for Energy Storage Research, University of Illinois at Urbana-Champaign, 505 South Matthews Avenue, Urbana, IL, 61801, USA.
authors.forename: Jeffrey S
authors.initials: JS
authors.lastname: Moore
authors.affiliation: Joint Center for Energy Storage Research, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA, 94720, USA.|The Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA, 94720, USA.
authors.forename: Brett A
authors.identifier: 0000-0003-3925-4174
authors.initials: BA
authors.lastname: Helms
keywords: energy storage; macromolecular chemistry; membranes; polymers; redox-flow batteries