Robust Nitrogen-Doped Porous Carbon Encapsulated Nico2s4 Nanodecahedrons for Enhanced Lithium Storage

Abstract

Transition metal sulfides (TMSs) are attractive anode materials for lithium-ion batteries (LIBs) due to their cost effectiveness, impressive redox properties, and high specific capacity. Among them, NiCo2S4 stands out with a substantial theoretical capacity of 703 mAh g−1 and a high electronic conductivity of 1.25 × 106 S m−1, making it a strong candidate for LIBs. However, NiCo2S4 experiences volume changes and mechanical stress during long-term cycling, leading to structural degradation and rapid capacity decay, which hinders its application. To address this issue, dodecahedral NiCo2S4/NC materials with a nitrogen-doped porous carbon structure have been developed. The optimized NiCo2S4/NC-300 material exhibits minimum charge transfer resistance, maximum pseudo-capacitive contribution, and exceptional lithium storage performance. At 0.1 A g−1, NiCo2S4/NC-300 exhibits an initial discharge/charge specific capacity of 1730.1/949.4 mAh g−1 and retains a discharge capacity of 454.4 mAh g−1 after 100 cycles. Even at 0.5 A g−1, it delivers an initial discharge/charge capacity of 1301.1/540.1 mAh g−1 with a capacity retention of 81.2% after 500 cycles. This study provides valuable insights into improving the energy density and cyclic stability of TMS anode materials for high-power LIBs.

Keywords: NiCo2S4, Nitrogen-doped porous carbon, Anodes, Lithium storage