Double-layer carbon coating enhanced silicon-based anode for lithium-ion batteries

Abstract

Silicon (Si)-based anode is widely recognized as one of the most promising anode materials in the next generation of lithium-ion batteries (LIBs) due to its high specific capacity. However, the commercialization of Si-based materials is still constrained by their poor cycle life and rate performance. Herein, Si@rGO@PNC/C composite with a double-layer carbon structure by combining needle coke (NC) and pitch with graphene coated Si nanoparticles (NPs) is synthesized with a secondary coating process followed by high-temperature calcination. The internally needle coke and pitch can effectively relieve the volume expansion of 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. With the merits of unique double-layer carbon structure, Si@rGO@PNC/C anode delivers a high specific capacity of 1043.0 mA h g-1 at the current density of 200 mA g-1, superior rate performance of a specific capacity retention of 84.3% and excellent cycling stability. This work gives insight into the valuable structural design of the practical application and development of Si-based anode for LIBs.