ZnSe/SnSe hollow microcubes as cathode for high performance aluminum ion batteries.

Advances in cathode material design and understanding of intercalation mechanisms are necessary to improve the overall performance of aluminum ion batteries. Therefore, we designed ZnSe/SnSe hollow microcubes with heterojunction structure as a cathode material for aluminum ion batteries. ZnSe/SnSe hollow microcubes with an average size of about1.4 µm were prepared by selenization of ZnSn(OH) microcubes successfully. The shell thickness of ZnSe/SnSe hollow microcubes is about 250 nm. On one hand, the hollow cubic structure can effectively alleviate the volume effect, provide shorter ion diffusion paths, and increase the contact area with the electrolyte. On the other hand, ZnSe/SnSe heterojunction structure can establish a built-in electric field to facilitate ion transport. The synergistic effect of the two leads to the improved electrochemical performance of ZnSe/SnSe as the cathode of aluminum ion batteries. The material delivered a reversible capacity of 124 mAh/g after 150 cycles at a current density of 100 mA/g. Meanwhile, coulombic efficiency remained above 98% in almost all cycles. In addition, the electrochemical reaction mechanism and kinetic process of Al and ZnSe/SnSe were studied.