NiS₂/FeS Heterostructured Nanoflowers for High-Performance Sodium Storage

Transition metal sulfides demonstrate attractive potential for sodium storage owing to their high theoretical specific capacity and high reserve. However, the low conductivity and volume expansion deteriorate their high-rate performance and cycling stability. In this work, we construct NiS₂/FeS heterostructure by growing Ni-based layered double hydroxide nanosheets on Fe-based Prussian Blue nanocrystals followed by gaseous sulfurization, giving rise to flower-like NiS₂/FeS nanoparticles. The as-prepared nanocomposite exhibits good rate performance of 156 mAh g⁻¹ at 50 A g⁻¹ and long cycle life of 606 mAh g⁻¹ at 5 A g⁻¹ after 1,000 cycles, which are superior to the heterostructure-free counterpart of NiS₂ and FeS. Density functional theory calculation further verifies that the enhanced electrochemical performance of NiS₂/FeS is due to the existence of interface derived from the heterostructure.