Constructing Multilayer Hollow Graphene Spheres on Needle Coke Via Nickel Acetate Catalysis for High-Performance Silicon/Graphite Composite Anodes

Coal-based needle coke can be converted into artificial graphite via high-temperature graphitization to serve as the anode material in the preparation of silicon/graphite composites. However, the graphitization treatment is an energy-intensive process, and the rigid structure of graphite imposes a limitation on the silicon content in silicon/graphite composites. To address these challenges, this study employed a nickel-catalyzed low-temperature graphitization strategy. This method generated multilayer hollow graphene spheres on the graphitized needle coke, forming a distinct architecture that effectively buffers silicon volume expansion and ensures the structural stability. With the further enhancement of overall electrical conductivity provided by a few-layer graphene coating, the silicon/graphite composite electrode prepared with a nickel acetate to needle coke mass ratio of 8:1 delivered the optimal electrochemical performance, achieving a highly reversible specific capacity of 983.4 mAh g–1 at a current density of 0.2 A g–1 and a high capacity retention of 92.0% after 1000 cycles at 1 A g–1. Moreover, as a practical application, the full cell delivers an outstanding capacity retention of 89.7% after 100 cycles at 1C, demonstrating considerable promise for commercial application.