Se‐Doping on Co4S3 Cathode Based on Soft Anion Chemistry to Enhance Magnesium Storage Performance

Abstract Rechargeable magnesium batteries (RMBs) have gradually got attention due to the high theoretical capacity, low cost and high security. However, the lack of suitable cathode materials has been a major obstacle to the development of RMBs. Transition metal sulfides (TMSs) have been studied extensively because of their high theoretical specific capacity and other advantages. However, the diffusion rate of Mg 2+ in TMSs is slow and side reactions are easy to occur. In this work, soft anion doping strategy was adopted at Co 4 S 3 cathode material. After doping the appropriate content of Se, it showed the specific capacity of 248 mAh g −1 at a current density of 100 mA g −1 . The mechanism of magnesium storage was investigated by ex‐situ technique. This work laid a foundation for researching cobalt‐based sulfide in cathode materials of RMBs.