Implications of electrode modifications in aqueous organic redox flow batteries

Abstract

Aqueous organic redox flow batteries (RFBs) exhibit favorable characteristics, such as tunability, multielectron transfer capability, and stability of the redox active molecules utilized as anolytes and catholytes, making them very viable contenders for large-scale grid storage applications. Considerable attention has been paid on the development of efficient redox-active molecules and their performance optimization through chemical substitutions at various places on the backbone as part of the pursuit for high-performance RFBs. Despite the fact that electrodes are vital to optimal performance, they have not garnered significant attention. Limited research has been conducted on the effects of electrode modifications to improve the performance of RFBs. The primary emphasis has been given on the impact of electrode engineering to augment the efficiency of aqueous organic RFBs. An overview of electron transfer at the electrode–electrolyte interface is provided. The implications of electrode modification on the performance of redox flow batteries, with a particular focus on the anodic and cathodic half-cells separately, are then discussed. In each section, significant discrepancies surrounding the effects of electrode engineering are thoroughly examined and discussed. Finally, we have presented a comprehensive assessment along with our perspectives on the future trajectory.