MRS Energy & Sustainability

Merits and drawbacks of representative inorganic and organic redox active electrolytes used in aqueous redox flow batteries are discussed. Appropriate assessment and reporting methods of the cycling stability of electrolyte materials are recommended. Future directions in developing advanced electrolyte materials are presented. Redox flow batteries represent a viable technology for scalable energy storage. However, widespread market adoption of flow battery technologies is significantly impeded by the lack of robust, low-cost redox active electrolyte materials. In this perspective, we highlight the merits and drawbacks of representative inorganic and organic redox active electrolytes. We also provide a number of research strategies to develop high-performance redox active electrolytes to enable energy dense, durable, low-cost flow battery technologies.