cPAN-coated nano-silicon combined with graphite as anode for high performance lithium-ion batteries

Silicon (Si) has a high theoretical specific capacity (around 4200 mAh g−1), a suitable operating voltage and abundant resources, making it a promising anode material for lithium-ion batteries (LIBs). However, the structural collapse and low conductivity of the silicon negative electrode during the repeated charging and discharging seriously hinder its commercial application. In this study, 3D silicon@cyclized polyacrylonitrile@graphite (Si@cPAN@G) composites were prepared by simple ball milling and heat treatment. As the anode material of the LIBs, the volume expansion and contraction of Si can be effectively restrained by depositing a thin (∼3 nm) cPAN film on the surface of Si during charging and discharging. The introduction of graphite sheets can not only effectively prevent the agglomeration of Si@cPAN nanoparticles, but also provide an effective electron transport channel for active materials. At the same time, the graphite sheets can further disperse the stress generated during the cycling of the Si nanoparticles. Due to the synergistic effect of graphite and cPAN coating, Si@cPAN@G exhibits excellent electrochemical performance. The initial coulomb efficiency of the Si@cPAN@G composite is 88.7% and the specific discharge capacity is 1392.2 mAh g−1 after 150 cycles at 0.5 A g−1.