Engineering of CuSx@C derived from Cu-MOF as long-life anodes for sodium-ion batteries

Abstract Copper sulfides are proved to be good candidates as anode materials for sodium ion batteries due to their abundant resources, moderate cost, and relatively high electrical conductivity. However, poor rate performance and cycling life still hinder their development as anode materials for sodium-ion batteries. Herein, we synthesized carbon-coated copper sulfide nanorod assembled into octahedron composites (CuSx@C) by sulfuration of a Cu-based metal-organic framework (Cu-MOF) under different temperatures. These composites with hierarchical structure exhibited superstable cycling performance as anodes of sodium-ion batteries. The CuSx@C sample obtained under 500 ​°C showed discharge capacity of 208 ​mA ​h ​g-1 ​at 2 ​A ​g-1 over 6300 cycles. Porosity and hierarchical stucture facilitate the storage of sodium ion, and carbon-coated structure buffers volume change of anode materials during the electrochemical reaction.