Two-Dimensional Porous Sandwich-Like C/Si-Graphene-Si/C Nanosheets for Superior Lithium Storage.

A novel two-dimensional porous sandwich-like Si/carbon nanosheet is designed and successfully fabricated as an anode for superior lithium storage, where a porous Si nanofilm grows on the two sides of reduced graphene oxide (rGO) and is then coated with a carbon layer (denoted as C/Si-rGO-Si/C). The coexistence of micropores and mesopores in C/Si-rGO-Si/C nanosheets offers a rapid Li+ diffusion rate, and the porous Si provides a short pathway for electric transportation. Meanwhile, the coated carbon layer not only can promote to form a stable SEI layer, but also can improve the electric conductivity of nanoscale Si coupled with rGO. Thus, the unique nanostructures offer the resultant C/Si-rGO-Si/C electrode with high reversible capacity (1187 mA h g-1 after 200 cycles at 0.2 A g-1 ), excellent cycle stability (894 mA h g-1 after 1000 cycles at 1 A g-1 ), and high rate capability (694 mA h g-1 at 5 A g-1 , 447 mA h g-1 at 10 A g-1 ).