Facile synthesis of N-C/Si@G nanocomposite as a high-performance anode material for Li-ion batteries

Abstract

Nitrogen-doped carbon wrapped Si nanoparticles (NPs) hybridized with 3D graphene conductive network (N-C/Si@G) is developed as a novel nanocomposite for lithium-ion battery (LIB) anodes. The nanocomposite is synthesized via a facile technique that involves self-assembly of Si NPs (~50 nm) with graphene oxide (Si@GO) and formation of mixture of Si@GO and polyacrylonitrile (PAN) in the presence of dimethyl sulfoxide (DMSO), followed by a carbonization treatment under a temperature of 750 °C. Si NPs encapsulated in nitrogen-doped amorphous carbon shell are completely filled in a 3D graphene network. When employed as a LIB anode, N-C/Si@G was able to achieve a high specific capacity of 1750 mAh g−1 at a current density of 0.1 A g−1. In addition, the N-C/Si@G nanocomposite showed the excellent cyclic performance with a specific capacity of ~701 mAh g−1 at 5 A g−1 over 800 cycles. Based on the collective results, the enhanced electrochemical performance of N-C/Si@G nanocomposite might be largely ascribed to the synergistic effect arised from N-doped carbon shell and large void space of the 3D graphene network. Individually, N-doped carbon shell can help to enhance the overall electronic conductivity of the material, while the large void in 3D graphene network can provide enough space to accommodate the severe volume change of Si NPs.