The Conversion-Type Selenides as Potential High-Energy Cathode Materials for Mg-Based Batteries: A Review

Based on the intrinsic restrictions in current lithium-ion battery, Mg-based batteries are regarded as one of the most potential candidates because of their higher volumetric energy density and fewer Mg dendrites in the process of charge and discharge. However, the improved energy density of the Mg-based battery is expected to further promote their practical application. Compared with metal chalcogenides, the selenides have high electrical conductivity and special electron orbit mixing effect between the Se and the transition metal atoms. As a result, the conversion-type selenides are promising cathodes for Mg batteries with high-energy- density. Herein, this review focuses on the recent investigations on the metal selenides as cathode materials for Mg-based batteries. Their crystal structures, the preparation methods, and electrochemical properties/mechanism of transition metal selenides are unveiled. Finally, the issues and the future research of selenides for Mg batteries are discussed, such as advanced characterization methods and rational design strategies. These advances of selenides provide new ideas for realizing the characteristics of high-energy-density Mg-based batteries.