Controlling the phenolic resin-based amorphous carbon content for enhancing cycling stability of Si nanosheets@C anodes for lithium-ion batteries

Carbon-coated Si nanosheets (Si NSs@C) nanocomposites with different carbon contents are successfully controlled and synthesized by the method of DC arc-discharge plasma, followed by phenolic resin pyrolysis at high temperature. The electrochemical performances of these nanocomposites as the anodes of lithium-ion batteries (LIBs) are investigated. The Si NSs with an average size of 31 nm and a thickness of 2.4 nm are surrounded by phenolic resin-derived amorphous carbon, forming a cladding structure. In the nanocomposites, Si NSs play a leading role in the reaction with Li+ ions, while the amorphous carbon mainly provides a highly conducive matrix for good contact among Si NSs active phases, which further facilitates the diffusion and transport of Li+ ions and electrons. The carbon matrix can also protect Si NSs from direct contact with the electrolyte, to ensure the formation of stable SEI films in cycles. Electrochemical performances indicate that the Si NSs@C nanocomposite electrode with the carbon content of 66.4 wt% delivers a stable discharge specific capacity of 822 mAh g(-1) at a current density of 100 mA g(-1) after 200 cycles and a better rate capability, confirming the predominant role of the controlled carbon content in the enhancement of the cycling stability of such Si-based anodes for LIBs.