Recent Developments on Electroactive Organic Electrolytes for Non‐Aqueous Redox Flow Batteries: Current Status, Challenges, and Prospects

Abstract

AbstractThe ever‐increasing threat of climate change and the depletion of fossil fuel resources necessitate the use of solar‐ and wind‐based renewable energy sources. Large‐scale energy storage technologies, such as redox flow batteries (RFBs), offer a continuous supply of energy. Depending on the nature of the electrolytes used, RFBs are broadly categorized into aqueous redox flow batteries (ARFBs) and non‐aqueous redox flow batteries (NARFBs). ARFBs suffer from various problems, including low conductivity of electrolytes, inferior charge/discharge current densities, high‐capacity fading, and lower energy densities. NARFBs offer a wider potential window and range of operating temperatures, faster electron transfer kinetics, and higher energy densities. In this review article, a critical analysis is provided on the design of organic electroactive molecules, their physiochemical/electrochemical properties, and various organic solvents used in NARFBs. Furthermore, various redox‐active organic materials, such as metal‐based coordination complexes, quinones, radicals, polymers, and miscellaneous electroactive species, explored for NARFBs during 2012–2023 are discussed. Finally, the current challenges and prospects of NARFBs are summarized.