Two-dimensional sandwich-like Ag coated silicon-graphene-silicon nanostructures for superior lithium storage

Abstract

Two-dimensional (2D) sandwich-like Ag coated silicon-graphene-silicon (Ag@Si-rGO-Si) nanosheets are designed and synthesized as a novel anode material for superior lithium storage. The mesoporous Si nanofilm grows tightly on the two sides of reduced graphene oxide (rGO), and Ag nanoparticles with a size of 10–50nm are further coated on the surface of porous Si nanofilm. Such unique features not only provide a short pathway for rapid Li+ diffusion and electron transportation, but also can act as a buffering effect to effectively inhibit the huge volume expansion of pure Si during the repeated lithiation/delithiation process. Meanwhile, a conductive network is constructed by the embedded graphene coupled with Ag nanoparticles to overcome the shortage of pure Si with low electrical conductivity. The resultant 2D sandwich-like Ag@Si-rGO-Si electrode exhibits a high reversible capability (1382mAhg−1 at 0.1Ag−1 after 100 cycles), long cycle stability (952mAhg−1 at 1Ag−1 after 500 cycles) and excellent high-rate performance (863mAhg−1 at 2Ag−1, 565mAhg−1 at 5Ag−1).