Speaker
Description
Redox flow batteries, which utilize solutions of active materials (anolyte and catholyte) rather than the solid state electrodes found in conventional batteries, are highly promising for stationary energy storage applications. Whereas most redox flow cells are based on metallic active species in aqueous media, we have been working on developing flow batteries based on solutions of redox active organic compounds in organic solvents that have the potential for higher energy density. Organic compounds with high redox potentials, which can be used for catholyte solutions, are available, but in order to take advantage of the high cell potentials that are possible in organic solvents, new organic anolyte materials with lower redox potentials are needed. This presentation will outline our assessment of bispyridinylidene-based anolytes in a totally organic batteries featuring a catholyte based on 2,2,6,6-tetramethyl-1-piperidinyloxy. The bispyridinylidene is a relatively low voltage two-electron donor that can be modified to improve its solubility and to limit its ability to diffuse through the ion exchange membrane. Though cycle life needs to be improved, the cells display good coulombic and voltage efficiencies, and operate at ~ 2 V.