CuFeS₂ Nanosheets Assembled into Honeycomb-like Microspheres as Stable High-Capacity Anodes for Sodium-Ion Batteries

As an anode in sodium-ion batteries (SIBs), chalcopyrite (CuFeS2) has aroused tremendous interest owing to its earth-abundant elements and high theoretical specific capacities. Because ingenious nanostructures of electrode materials can significantly improve their energy storage properties, in this paper, CuFeS2 nanosheets have been assembled into honeycomb-like microspheres by a facile solvothermal method. The performance of the CuFeS2 product with the honeycomb-like microsphere structure is analyzed by several physicochemical characterizations. The results indicate that the microsphere structure of CuFeS2 can improve the energy storage properties of the anode material when it is used in SIBs. Specially, the reversible capacity is up to 528 mA h g–1 after 100 cycles, over 86.4% of initial capacity retentions, and an excellent cycling stability is achieved. Moreover, the CuFeS2 microsphere can buffer the volume expansion due to the unique layer structure. Therefore, CuFeS2 nanosheet-assembled honeycomb-like microspheres can significantly improve the energy storage properties of electrode materials during the discharging and charging processes, and it shows great promise to become the next-generation electrode material for large-scale energy storage.