Preparation of free-standing flexible nano-silicon/graphene composite paper electrode for lithium-ion batteries

Silicon possesses an extremely high theoretical specific capacity of 4200 mAh/g, which is about more than ten times higher than that of commercial graphite, thus is a promising anode material for lithium ion batteries. However, during the charge/discharge process, Si particles pulverize and crack due to the huge volume expansion, leading to dramatic decrease on the specific capacity. This work is the first to successfully fabricate free-standing flexible nano-silicon/graphene paper electrode via hydrothermal reduction. SEM showed that Si nanoparticles are homogenously dispersed on the graphene nanosheets. The Si/rGO paper electrode exhibits a significantly improved electrochemical performance than the pristine Si, owing to the excellent flexibility of graphene which suppresses the pulverization of Si particles as well as its excellent electrical conductivity. Moreover, the low reduction temperature enables the paper thickness unchanged after hydrothermal reduction, which facilitates the close contact between Si nanoparticles and graphene nanosheets. This composite paper shows an initial specific discharge capacity of 4003 mAh/g at a current density of 100 mA/g (close to the theoretical capacity of silicon), and maintains a high specific capacity of about 3300 mAh/g after 20 cycles and 1000 mAh/g after 50 cycles. © 2016, Materials Review Magazine. All right reserved.