A Self-Trapping, Bipolar Viologen Bromide Electrolyte for Aqueous Redox Flow Batteries

12 June 2020, Version 2
This content is a preprint and has not undergone peer review at the time of posting.

Abstract

Aqueous organic redox flow batteries (AORFBs) have become increasing attractive for scalable energy storage. However, it remains challenging to develop high voltage, powerful AORFBs because of the lack of catholytes with high redox potential. Herein, we report methyl viologen dibromide ([MV]Br2) as a facile self-trapping, bipolar redox electrolyte material for pH neutral redox flow battery applications. The formation of the [MV](Br3)2 complex was computationally predicted and experimentally confirmed. The low solubility [MV](Br3)2 complex in the catholyte during the battery charge process not only mitigates the crossover of charged tribromide species (Br3-) and addresses the toxicity concern of volatile bromine simultaneously. A 1.53 V bipolar MV/Br AORFB delivered outstanding battery performance at pH neutral conditions, specifically, 100% total capacity retention, 133 mW/cm2 power density, and 60% energy efficiency at 40 mA/cm2.

Keywords

Energy storage
redox flow batteries
viologen
bromine
redox active molecules

Supplementary materials

Title
Description
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Title
200605-MVBr2-SI
Description
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Title
200605-MVBr2-SI
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Title
200605-MVBr2-Main-ChemRxiv
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