Zinc oxide assisted synthesis of a holey carbon shell and graphene sheet supported silicon nanoparticle composite anode for lithium-ion batteries

Abstract

Nanosized Si has shown the potential as an alternative anode material for lithium-ion batteries. But this material suffers from the inherent problems such as severe self-aggregation and low electric conductivity. Herein, Si nanoparticles are immobilized by a hierarchical supporting framework constituted by holey amorphous carbon shell and reduced graphene oxide (RGO) sheet to synthesize a Si@C/RGO composite. ZnO nanoparticles play the key assistant role in sample synthesis. Firstly, ZnO nanoparticles from the Si@C@ZnO intermediate product work as a catalyst toward graphene oxide (GO) reduction to engineer an RGO coating layer in a mild hydrothermal condition. Then, these ZnO nanoparticles are used as sacrificial template to construct buffering holey carbon shells in the final Si@C/RGO composite. The hierarchical Si@C/RGO composite delivered improved electrochemical properties than the routine Si@C counterpart, which has an initial coulombic efficiency of about 73.5% and a good reversible capacity about 674 mAh·g−1 at the 500th cycle under the current rate of 200 mA·g−1. The hierarchical holey carbon shell and RGO coating layer supporting framework synthesized by the assistance of ZnO nanoparticles may be further used for the improvement of other electrochemically active materials for energy conversion and storage.