Storing Mg Ions in Polymers: A Perspective.

The electrochemical performance of rechargeable Mg batteries (RMBs) is primarily determined by the cathodes. However, the strong interaction between highly polarized Mg 2+ and the host lattice is a big challenge for inorganic cathode materials. While endowed with weak interaction with Mg 2+ , organic polymers are capable of fast reaction kinetics. Besides, with the advantages of light weight, abundance, low cost, and recyclability, polymers are deemed as ideal cathode materials for RMBs. Although polymer cathodes have remarkably progressed in recent years, there are still significant challenges to overcome before reaching practical application. In this perspective, the challenges faced by polymer cathodes are critically focused, followed by the retrospection of efforts devoted to design polymers. Some feasible strategies are proposed to explore new structures and chemistries for the practical application of polymer cathodes in RMBs.