Fabrication and Performance of Symmetric Flow Battery Systems Incorporating Novel Pyridinium Anolytes

Abstract

The push to bring more renewable energy sources onto the grid has spawned a flurry of work to develop viable options for long duration energy storage. Redox flow batteries (RFBs) represent one of the most attractive possibilities, and research toward employing redox-active organic materials to improve or replace the incumbent commercially available vanadium-based RFB technology is burgeoning. In particular, numerous pyridinium-based salts have been extensively studied as anolytes in both aqueous and nonaqueous RFBs. We have recently reported a series of readily synthetically accessible 2,6-dimethyl-4-arylpyridinium compounds that display quite negative reduction potentials (ca. -1.55 to -1.8 V vs Fc/Fc+), along with high solubility and excellent electrochemical kinetics. Some of these materials are also extremely persistent in the reduced state, suggesting that they may be good candidates for RFB applications.In this presentation, we will describe the preparation and properties of new pyridinium compounds from the corresponding pyrylium precursors, as well as the fabrication of symmetric RFB systems in which these materials are covalently linked to phenothiazine or ferrocene catholyte moieties. Synthesis, solubility, and electrochemical performance (including preliminary RFB cycling data) of these materials will also be discussed.