Rational-design micro-nanostructure of porous carbon film/silicon nanowire/graphite microsphere composites for high-performance lithium-ion batteries

Silicon-based anodes are promising anode materials for lithium-ion batteries. However, during the charge–discharge processes, the huge volume change of silicon leads to the repeated formation of solid-electrolyte interphase layer, structure fracture and loss of electric contact, which seriously limits their practical applications. In this paper, a rational design combining graphite microsphere, silicon nanowire and porous carbon film is established, forming a micro-nanostructure that can effectively solve the above issues. Employing chemical vapor deposition method, silicon nanowire and polypyrrole are successively in situ synthesized on the graphite surface. After carbonizing the deposited composites, a porous carbon film and a silicon carbide layer locating between silicon and carbon film are obtained. It establishes a novel microstructure that possesses a strong bonding strength among interfaces of carbon film/silicon and silicon/graphite. Therefore, the porous carbon film/silicon nanowire/graphite microsphere composites anode exhibits a high capacity of 530 mA h g−1 at a current density of 0.2 C after 100 cycles. Significantly, the prepared composites anode could satisfy the practical application because their initial coulomb efficiency can reach to 80%.