Facile Synthesisof Graphite-SiO_x/C Core–Shell CompositeAnode for High Stable Lithium-IonBatteries

Abstract

Graphite-silicon composite anodes have been regarded as some of the most practical next-generation anode materials for commercialization. However, poor interfacial contact between Si and graphite and serious volume expansion of Si always lead to even worse electrochemical performances than the pure graphite anode. Herein, we report a stable graphite-SiO_x/C composite anode (Gr@SiO_x/C) with a homogeneous SiO_x/C coating layer on the surface of graphite via a facile sol–gel process and subsequent pyrolysis. SiO_x/C can enhance the overall capacity of the composite anode while possessing a low volume expansion, which is beneficial to maintaining structural stability. Furthermore, the homogeneous distribution of SiO_x and C frameworks also enables rapid and stable Li⁺/electron transport toward the graphite inner core. As a result, the as-prepared Gr@SiO_x/C composite anode exhibits excellent cycling stability and rate capability with more than twice the capacity of graphite at 1 A g^–1. A full cell assembled with NCM811 cathode delivers a high stable cycling performance with a capacity retention exceeding 90% after 300 cycles and an average Coulomb efficiency of 99.24%. This work is expected to provide a reference for the rational design of graphite-silicon composite anodes in lithium-ion batteries.