Highly conductive C-Si@G nanocomposite as a high-performance anode material for Li-ion batteries

Abstract

A novel hybrid material of carbon-coated Si nanoparticles (NPs) encapsulated in 3D graphene network (C-Si@G) was facilely synthesized by the assembly of graphene oxide-encapsulated Si NPs followed by a soldering treatment with carbon derived from polyvinylidene fluoride (PVDF) at a carbonization temperature. The amorphous carbon-coated Si NPs of ∼50 nm in diameter were completely wrapped in 3D conductive graphene network. As a negative electrode material of lithium-ion batteries (LIBs), C-Si@G nanocomposite delivered a superior Li-storage capacity of 2883.1 mAh g−1 under a constant rate of 0.1 A g−1. Meanwhile, a stable cycling performance with a specific capacity of ∼752 mAh g−1 was achieved after 270 cycles for C-Si@G nanocomposite at a rate of 5 A g−1. The superior electrochemical properties of C-Si@G with respect to the desirable capacity, reliable cyclic performance, and high rate ability were attributed to the significantly enhanced electrical conductivity by carbon coating and void space of 3D graphene to buffer the severe volume variation of Si NPs as well as enhanced charge transfer ability and promoted lithiation process of the anode.