Structure-Designed Preparation of Pod-Like CuCo₂S₄/rGO as Advanced Anode Material Targeting Superior Sodium Storage

It is urgent to design and assemble anode materials with long cycling life and high capacity for sodium-ion batteries (SIBs). Thereby, pod-like CuCo₂S₄/rGO, with a unique core-shell structure, was successfully fabricated through a solvothermal method, a green reduction process, and a following liquid-nitrogen treatment. CuCo₂S₄ spheres were embedded into rGO nanosheet scrolls, forming a unique pod-like structure due to the shrinkage of rGO during the liquid-nitrogen treatment. The pod-like CuCo₂S₄/rGO material exhibits a superior electrochemical performance compared to bare CuCo₂S₄, including a high capacity (557.5 mAh g⁻¹ at 0.1 A g⁻¹) and good rate capability (372 mAh g⁻¹ at 2 A g⁻¹). In addition, a long cycling life with a high capacity of 341 mAh g⁻¹ over 5000 cycles at 2 A g⁻¹ is achieved. The improved electrochemical performance can be ascribed to the unique pod-like core-shell structure, which cannot only provide efficient pathways to facilitate electron/ion transportation, but also relieve the strain caused by volume change to maintain the structural stability. This work offers a simple strategy to prepare rGO-wrapped CuCo₂S₄ nanocomposites with stable pod-like structure, proving their potential application as anode materials for SIBs.