A Bispyridinylidene Anolyte for an All-Organic Redox Flow Battery

Abstract

Global warming associated with CO2 emissions caused by the excessive use of fossil fuels has become a worldwide concern. The use of renewable energy resources as an alternative power source can help reduce the amount of CO2 in air. Redox flow batteries (RFBs) have attracted a lot of attention recently as promising systems for energy storage from intermittent renewable resources and to allow integration with the power grid. Most RFBs are based on metallic active species in aqueous media, however there is a growing interest around the use of soluble organic redox couples in non-aqueous solvents to achieve higher energy density. Organic compounds with high redox potentials (catholyte) are readily available, but new organic compounds that undergo multi-electron redox processes at a low redox potential (anolyte) are needed to boost the energy density of RFBs. This presentation will outline efforts to demonstrate a new bispyridinylidene-based anolyte that undergoes a reversible two-electron oxidation (-1.69 V vs. ferrocene) and assess its applicability in a RFB. In addition to stability tests for the bispyridinylidene, an all-organic non-aqueous RFB employing 2,2,6,6-tetramethyl-1-piperidinyloxy and bispyridinylidene as cathodic and anodic active materials, respectively has been investigated.