High-Capacity and Stable Lithium Storage in Ni/NiO@NiS@GN Heterostructure Anode Enabled by Synergistic Effects and Graphene Confinement

This study investigates the synthesis, structure, and electrochemical performance of Ni/NiO@NiS and its composite with few-layer graphene (GN) as anode materials for LIBs. Ni/NiO was first synthesized via thermal treatment, followed by the hydrothermal growth of rod-like NiS on Ni/NiO particles to form Ni/NiO@NiS. Subsequently, Ni/NiO@NiS@GN was prepared by incorporating GN into the composite. Characterization by Transmission Electron Microscope etc. confirmed the successful formation of heterostructures with mesoporous features and a specific surface area of 25.74 m2·g−1 for the GN composite. Electrochemical tests showed that Ni/NiO@NiS@GN delivered a high discharge specific capacity of 1005.6 mAh·g−1 after 100 cycles at 0.1 C and excellent rate performance (517.37 mAh·g−1 at 5 C), with a capacity recovery of 84.9% when returning to 0.1 C. The enhanced performance is attributed to the synergistic effects among Ni, NiO, and NiS, combined with GN’s high conductivity and structural buffering. This work demonstrates that GN is an optimal carbon matrix for Ni/NiO@NiS anodes.