Bimetallic selenide Cu4Mo6Se8 nanosheet arrays grown on a carbon skeleton via MOF-derived with enhanced electrochemical kinetics for high-performance sodium-ion batteries

Abstract

Due to their high conductivity and theoretical capacity, transition metal selenides have drawn significant attention as promising electrode materials for sodium-ion batteries (SIBs). However, their limited cycle life and inferior rate capability are still thorny issues. In this article, we report for the first time ultrathin Cu₄Mo₆Se₈ nanosheet arrays directly grown on a carbon skeleton (CMSe/C) derived from a bi-metal organic framework (Cu–Mo BMOF) by the selenization reaction. When used as an anode material for SIBs, the CMSe/C electrode delivers ultrahigh coulombic efficiency (CE), outstanding rate performance (411 mA h g⁻¹ at 0.1 A g⁻¹ and 365 mA h g⁻¹ at 5.0 A g⁻¹) and excellent cycling performance at a high current density (474 mA h g⁻¹ at 2 A g⁻¹ after 2400 cycles). Firstly, the high CE for the CMSe/C electrode can be ascribed to the nanosheet arrays, bi-metal, and highly efficient electron transfer. Secondly, CMSe/C composites possess a 3D network structure with abundant void space consisting of CMSe nanosheets, which provides a necessary space for the expansion of CMSe nanosheets to accommodate volume changes during the cycle. Finally, ultrathin CMSe nanosheet arrays directly grown on carbon can improve the electrical conductivity and promote the formation of abundantly exposed edges and active sites, which can also promote outstanding electrochemical performance.