Efficient Sodium Storage in Cu1.96S@NC Anode Achieved by Robust S─C Bonds and Current Collector Self‐Induced Forming Cu2S Quantum Dots

Abstract

AbstractTransition metal sulfides are investigation hotspots of anode material for sodium‐ion batteries (SIBs) due to their structural diversity and high storage capacity. However, they are still plagued by inevitable volume expansion during sodiation/desodiation and an unclear energy storage mechanism. Herein, a one‐step sulfidation‐carbonization strategy is proposed for in situ confined growth of Cu1.96S nanoparticles in nitrogen‐doped carbon (Cu1.96S@NC) using octahedral metal–organic framework (Cu‐BTC) as a precursor and investigate the driving effect of Cu current collector on its sodium storage. The generation of S─C bonds in Cu1.96S@NC avoids the volume change and structural collapse of Cu1.96S nanoparticles during the cycling process and improves the adsorption and transport capacity of the material for Na+. More exciting, the Cu species in the Cu current collector are self‐induced forming Cu2S quantum dots to enter the original anode material during the initial few charging and discharging cycles, which unique small‐size effect and abundant edge‐active sites enhance the energy storage capacity of Cu1.96S. Thus, the Cu1.96S@NC exhibits a superior first discharge capacity of 608.56 mAh g−1 at 0.2 A g−1 with an initial Coulomb efficiency (ICE) of 75.4%, as well as provides excellent rate performance and long cycle durability up to 2000 cycles.