In-situ encapsulation of Ni₃S₂ nanoparticles into N-doped interconnected carbon networks for efficient lithium storage

Due to the conversion reaction induced high specific capacity, low cost and rich types, the interest on transition metal sulfides for efficient lithium storage has grown. Unfortunately, the intrinsically poor electrical conductivity and structure instability restrict their practical applications. Herein, an in-situ encapsulation strategy is developed to prepare the Ni₃S₂ nanoparticles encapsulated in interconnected N-doped porous carbon (Ni₃S₂@NC) through a facile freeze-drying approach and subsequent in-situ conversion. When evaluated as anode material for lithium-ion batteries (LIBs), the as-prepared Ni₃S₂@NC exhibits a remarkable lithium storage performance, including high reversible capacity (1335.4 mAh g⁻¹ after 100 cycles at 0.1 A g⁻¹), superior rate capability (507.7 mAh g⁻¹ at 4 A g⁻¹) and excellent long-term cycling stability (961.4 mAh g⁻¹ after 600 cycles at 0.5 A g⁻¹ and 862.8 mAh g⁻¹ after 600 cycles at 1 A g⁻¹), displaying one of the best lithium storage performances among the Ni₃S₂-based electrodes reported by now. Such an excellent lithium storage performance should be attributed to the unique structure advantages of Ni₃S₂@NC inherited from the in-situ encapsulation strategy, such as tight combination, increased electrical conductivity, shortened ion diffusion distance and buffering matrix provided by N-doped porous carbon networks. Importantly, the facile design and engineering strategy should also be applied to explore other nanoarchitectures to boost their lithium storage performances.