Developing New Chemistries for Redox Flow Batteries

Abstract

Aqueous organic redox flow batteries (AORFBs) have emerged as an attractive alternative RFB technology because redox active organic molecule materials are synthetically tunable, sustainable, and potentially low cost. The presentation will cover our recent research efforts in developing viologen anolyte materials for both anion and cation exchange pH neutral AORFBs with a variety of catholyte materials including ferrocene, TEMPO, ferrocyanide and halides. The viologen AORFBs demonstrated outstanding battery performance including an energy density of up to 30.4 Wh/L, a power density up to 220 mW/cm2, energy efficiency up to 72% at 60 mA/cm2, and capacity retention up to 99.999% per cycle up to 1000 cycles, representing the most stable organic RFB reported to date. In addition, this presentation will discuss mechanistic understandings of investigated redox active molecules using a variety of spectroscopic tools. Particularly, the presentation emphasizes that fundamental understandings of redox active electrolytes at molecular level are crucial to develop new generations of redox flow batteries for large scale and dispatchable renewable energy storage.