Nano Si embedded SiOx-Nb2O5-C composite as reversible lithium storage materials

Abstract

This study reports a simple and effective method for preparing nanocrystalline Si embedded carbon composites as a high-capacity anode material for Li-ion batteries. Micron-sized Si and Nb2O5 powders were used as starting materials for high-energy mechanical milling (HEMM) process. During the HEMM operation, Si particles obtained oxygen from Nb2O5; the nanocrystalline Si embedded SiOx phase was simultaneously created; and commmercial monoclinic Nb2O5 was also transformed to orthorhombic Nb2O5 with partial reduction. Results show that a nano Si embedded SiOx-niobium oxides-carbon composite was successfully synthesized. Material characterization of the composite was performed by X-ray diffraction analysis, X-ray photoelectron spectroscopy, and electron microscopies. Electrochemical test results demonstrate that the composite electrode has a greatly enhanced performance with a reversible capacity of about 800 mAh g−1 and excellent capacity retention of up to 200 cycles. This improvement can be attributed to the in-situ formation of the nanocrytalline Si embedded silicon suboxide phase with niobium oxides, which is dispersed in carbon matrix. It is considered that this finding will be useful in the preparation of robust Si-based anode materials for high-energy density Li-ion batteries.