Construction of carbon coated spherical Zn0.71Mn0.29Se@C for high-performance aluminum ion batteries

Abstract

As a high energy density material, selenides have shown highly competitive initial capacity when applied to the positive electrode of aluminum ion batteries. However, in acidic electrolytes, the volume effect of selenides during electrochemical reactions can cause damage to the material structure. In long-term cycling tests, the performance of selenide cathode materials deteriorates rapidly, which greatly limits the application of this high-performance material in aluminum ion batteries. Here, Zn0.71Mn0.29Se@C material was synthesized for the cathode of aluminum ion batteries, which is covered by a carbon layer on the sphere shells and has good crystallinity. Zn0.71Mn0.29Se@C showed excellent performance: the capacity was maintained at 102.79 mAh/g after 2000 cycles. Attributed to the supporting effect of the carbon material, Zn0.71Mn0.29Se@C exhibits excellent structural stability. During charging and discharging, the carbon layer of the sphere shell effectively limits the volume expansion and improves the cycling performance of the battery. Meanwhile, the simulation results show that the Zn0.71Mn0.29Se@C material has a strong trapping effect for AlCl4− ions. As the main ion involved in the reaction, this strong interaction can greatly improve the reaction kinetics. On the other hand, the charge accumulation caused by the embedding of potential ions enhances the charge transfer. In conclusion, the carbon layer in the outer layer of Zn0.71Mn0.29Se@C not only supports the sphere structure, but also enhances the trapping effect for potential ions, and this novel electrode material is expected to improve the application prospect of aluminum ion batteries.