Nitrogen-Doped Carbon-Coated Bimetal Selenides for High-Performance Lithium-Ion Storage through the Self-Accommodation of Volume Change

Owing to the problem of volume expansion during cycling, metal selenides with a high capacity and long-term cyclability are still very exploratory. In this work, we fabricate a Co/Zn-based multi-metallic metal organic framework at room temperature, and then select one-step selenization under an inert atmosphere to obtain the nitrogen-doped carbon-coated bimetal selenide composites. Originating from the nanoparticles-assembled porous structure, the in situ formed nitrogen-doped carbon coating, and the self-accommodation effect based on two components at stepwise Li reaction potentials, the nitrogen-doped carbon-coated bimetal selenide (Co/Zn-Se@NC) anodes deliver improved electrochemical properties. In particular, with the molar ratio (Co/Zn) changing, the Co/Zn-Se@NC-1 at Co/Zn=9 : 1 achieves high initial capacities (discharge/charge: 1040/788 mAh g(-1)) with 836 mAh g(-1) retained after 300 cycles. More efforts should be put into the exploration of mixed metal selenides and their composites with self-accommodation effects for applications in energy storage.