Electrospun carbon nanofiber anodes containing monodispersed Si nanoparticles and graphene oxide with exceptional high rate capacities

Carbon nanofiber (CNF) composites containing well-dispersed Si nanoparticles and graphene oxide (GO) are synthesized via electrospinning and carbonization of polyvinyl alcohol (PVA) precursor as freestanding electrodes of Li ion batteries. We first report the monodispersion of Si nanoparticles in aqueous solution via amino-silane functionalization followed by F ion mediation, prerequisite to excellent electrochemical performance of Si-based anodes. The treated Si nanoparticles are well bonded to the polymer precursor and fully encapsulated within amorphous carbon after carbonization which functions as stress buffer to relieve the volumetric strains generated by Si during charge/discharge cycles. The graphene (G) sheets offer extra conducting media for faster electron/ion charge transfer. The resulting Si/CNF/G electrodes deliver remarkable cyclic performance with a discharge capacity 872 mA h g−1 after 50 cycles and 91% capacity retention, along with an excellent high rate capacity 567 mA h g−1 at a current density 1.0 A g−1. These values are found among the best according to the comparison with reports on similar Si-based carbon electrode materials.