Mini-Review on the Redox Additives in Aqueous Electrolyte for High Performance Supercapacitors

Supercapacitors, also known as electrochemical capacitors, are attracting much research attention owing to their high power density, long-term cycling stability, as well as exceptional safety compared with rechargeable batteries, although the globally accepted quantitative benchmarks on the power density, cycling stability, and safety are yet to be established. However, it should be noted that the supercapacitors generally exhibit low energy density, which cannot satisfy the demands where both high energy density and power density are needed. To date, various methods have been employed Ito improve the electrochemical performances of supercapacitors. Among them, introducing redox additives (or redox mediators) into conventional aqueous electrolyte is regarded as one of the most proinising strategies. The redox additives in aqueous electrolyte are widely demonstrated to be able to increase Ithe charge storage capability via redox transformation and thus enhance the electrochemical performances. Herein we Present a brief review on the classification, state-of-the-art progress, challenges, and perspectives of the lredox additives in aqueous electrolyte for high performance supercapcitors.