Optimized interface and electronic transfer of metal-organic framework derived ZnSe-CoSe/Ti3C2Tx to facilitate lithium storage performance of conversion reaction anode

Abstract

ZnSe has high specific capacities, high electrochemical activity, and various electronic properties, which is considered as promising anode for lithium-ion storage. However, poor electronic conductivity and huge volume expansion during cycling are still the reasons for its limited electrochemical performance. Herein, the composites of ZnSe-CoSe anchored on MXene (ZnSe-CoSe@NC/MX) are synthesized by self-assembly and subsequent selenization. In ZnSe-CoSe@NC/MX composites, the ZnSe-CoSe nanoparticles, obtained by in-situ selenization of metal-organic frameworks (MOFs) at high temperature, are uniformly distributed on MXene sheets, developing robust interface with MXene through chemical bonds, which can enhance structure stability thus suppress the capacity fading during cycling. A heterostructure of CoSe and ZnSe is formed in the ZnSe-CoSe@NC polyhedron, and the generated built-in electric field further increases the ion mobility, raises the equilibrium reaction potential and decreases the activation barrier to trigger redox reactions. Therefore, the as-prepared ZnSe-CoSe@NC/MX exhibites a high capacity of 469.0 mAh g−1 at 0.2 A g−1 after 80 cycles, superior cyclic stability (327.0 mAh g−1 after 600 cycles at 1 A g−1), and excellent rate performance.