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 (CuFeS 2 ) 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, CuFeS 2 nanosheets have been assembled into honeycomb-like microspheres by a facile solvothermal method. The performance of the CuFeS 2 product with the honeycomb-like microsphere structure is analyzed by several physicochemical characterizations. The results indicate that the microsphere structure of CuFeS 2 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 CuFeS 2 microsphere can buffer the volume expansion due to the unique layer structure. Therefore, CuFeS 2 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.