Silicon Nanoparticles Wrapped in a Double-Layer Coating
of Chitin-Derived Nitrogen-Doped Carbon Nanosheet and Pitch-Based
Carbon Enabling Efficient Lithium Storage
Silicon
anode is considered to be the next-generation anode material
due to its high specific capacity. However, its commercial application
has been hindered by the significant volume expansion during charging
and discharging as well as its low conductivity. In this study, we
successfully synthesized carbon–silicon composites by double-layer
coating silicon nanoparticles with pitch-based carbon and N-doped
carbon nanosheets. The conductive network formed by N-doped carbon
nanosheets enhances the e–/Li+ transport
capacity of the material, and the pitch-based carbon can enhance the
bonding of Si and CNSs while avoiding the direct contact of Si with
the electrolyte. Thus, the double-layer coating structure not only
alleviates the mechanical stress caused by the volume expansion of
the active material but also enhances the transport capacity of electrons
and lithium ions within the composite. This leads to the creation
of additional active sites for lithium storage and an overall enhancement
of the electrochemical properties of the composite material. Particularly,
the anode (CNSs-Si-TS) demonstrates a high initial specific capacity
of 2069.3 mAh g–1 and a reversible capacity of 1441.8
mAh g–1 after 100 cycles at 0.2 A g–1. Even at 1 A g–1, its specific capacity maintains
708.07 mAh g–1 after 300 cycles. The design of a
double-layer coating structure provides a promising approach for the
preparation of carbon–silicon anode materials.