An enhanced double carbon layer-coated silicon-based anode for lithium-ion batteries

Abstract

Silicon (Si)-based anodes are widely recognized as one of the most promising anode materials in next-generation lithium-ion batteries (LIBs) due to their high specific capacities. However, the commercialization of Si-based materials is still constrained by their poor cycle life and rate performance. Herein, a Si@rGO@PNC/C composite with a double-layer carbon structure is synthesized through a secondary coating process followed by high-temperature calcination, in which graphene-coated Si nanoparticles (NPs) are combined with needle coke (NC) and pitch. The internal NC and pitch can effectively relieve the volume expansion of the Si NPs during the charge and discharge process. The external graphene provides a robust three-dimensional framework to improve the conductivity and structural stability of the material. Benefiting from its unique double-layer carbon structure, the Si@rGO@PNC/C anode delivers a high specific capacity of 1043.0 mA h g⁻¹ at a current density of 200 mA g⁻¹, along with superior rate performance with a specific capacity retention of 84.3% and excellent cycling stability. This work gives valuable insight into the structural design, development and practical applications of Si-based anodes for LIBs.