Si@Graphene composite anode with high capacity and energy density by fluidized chemical vapor deposition

Abstract

The scalable fluidized chemical vapor deposition (FCVD) methodology is developed to prepare the Si nanoparticles (NPs) coated with graphene (Si@G), where the high heat and mass transfer efficiencies avoid uneven coating of present coating technologies. The fluidization behavior of Si NPs is investigated by the computational fluid dynamics simulation, and the result is consistent with the experiment, which verifies the appropriate design of reactor and optimization of operating conditions. Taking advantage of the good electrical conductivity and mechanical strength of graphene, thin and uniform carbon layers strike a balance between suppressing volume expansion of Si NPs and increasing Li+ diffusion rate, which makes Si@G deliver the extraordinary electrode properties of capacity and cyclability. The Si@G/graphite composite containing 15 wt% Si@G affords a high capacity and capacity retention. Moreover, LFP//Si@G/graphite full cell is fabricated and possesses an ultrahigh energy density of 302 Wh kg−1, indicating the practical commercial application of Si@G.