Si nanoparticles/graphene composite membrane for high performance silicon anode in lithium ion batteries

Silicon is an exciting anode material with high specific capacity of 4200 mAh g−1, which is more than ten times the theoretical capacity of the commercialized graphite anode. However, successful applications of Si anode have been impeded by rapid capacity fading caused by large volume expansion (pulverization and subsequent electrical disconnection) during lithiation/delithiation and low ionic/electronic conductivity. Tackling the Si anode problems require a multifaceted design, which can simultaneously address the above-mentioned problems of Si-based anode. Herein, we present a facile approach to fabricate the freestanding Si/graphene composite membrane for Si anode in a large scale, allowing control over uniformly inserting Si nanoparticles into the pores between graphene sheets from nanoscale to macroscale. We demonstrate its high specific discharge capacities and excellent capacity retention. Over a long-term cycling of 1300 cycles at 400 mA g−1, a capacity decay as low as 0.06% per cycle and an average Coulombic efficiency of 99.8% was achieved.