Recent Advances and Perspectives of Impurity Ions and Additives for the Electrolyte of Vanadium Redox Flow Battery

The vanadium redox flow battery (VRFB) is an efficient electrochemical energy storage system, characterized by its energy efficiency, long cycle life, and scalability. The electrolyte, as a critical component of the VRFB, significantly affects the cost-effectiveness and operation performance of the battery. In the process of extracting vanadium from ores, residual impurities may contaminate the final products, resulting in the existence of impurity ions in the prepared vanadium electrolyte. Therefore, it is vital to investigate the influence of these impurity ions on the VRFB performance. The addition of appropriate additives can enhance the electrolyte performance. This review analyzes the mechanisms through which impurity ions and additives affect VRFB performance, providing a systematic overview of the influence of various potential impurities in the electrolyte. Additionally, the effects of both organic and inorganic additives on VRFB performance are discussed. Finally, future prospects for vanadium electrolytes and additives are explored. The aim of this article is to guide the development of cost-effective vanadium electrolytes and advance the commercialization of VRFB.