The preparation of carbon-coated Si nanofiber deposited on carbon nanofiber/natural microcrystalline graphite as the anode for lithium-ion batteries

Silicon (Si) is one of the most potential candidates for the next-generation anode material for lithium-ion batteries. Nevertheless, the practical application of Si anode is limited by low conductivity and large volume expansion during charge/discharge processes. Herein, hierarchical Si/C composites are prepared via two-step chemical vapor deposition method and one-step in situ polymerization, in which N-doped carbon-coated Si nanofiber was deposited on carbon nanofiber/natural microcrystalline graphite. Such structural design is beneficial to restrict the volume expansion of Si and enhance the conductivity of electrode material. Moreover, derived silicon carbide at the interface between carbon nanofiber with silicon greatly improves the bonding ability, preventing the separation of Si from carbon fibers. Therefore, the composites can provide a reversible capacity of 528.3 mA h g−1 after 100 cycles at a current density of 100 mA g−1 and display good rate capability (the capacity retention rate is 89.8% after charging and discharging under different currents).