Electrode materials for vanadium redox flow batteries: Intrinsic treatment and introducing catalyst

• The modification methods of vanadium redox flow battery electrode were discussed. • Modifying the electrode can improve the performance of vanadium redox flow battery. • Synthetic strategy, morphology, structure, and property have been researched. • The design and future development of vanadium redox flow battery were prospected. Vanadium redox flow battery (VRFB) is considered to be one of the most promising renewable energy storage devices. Although the first generation of VRFB has been successfully implemented in many projects, its low energy efficiency limits its large-scale application. The redox reaction of vanadium ions has an important influence on the energy efficiency of VRFB. However, the pristine carbon-based materials have poor catalytic activity on vanadium ion and cannot meet the demand. Therefore, in order to improve the catalytic activity of carbon-based materials on vanadium ion, the modification of carbon-based materials has received extensive attention. In this review, the research progress on the modification of carbon-based materials was discussed from the aspects of intrinsic treatment and introduction of catalysts. Intrinsic treatment is mainly reviewed from thermal treatment, acid treatment, electrochemical treatment, chemical etching and heteroatom doping, etc. Introduction of catalysts is mainly reviewed from the introduction of metal, metal compounds, carbon-based, and other catalyst, etc. Finally, practical suggestions are put forward for the further development of VRFB.