Promotional role of B2O3 in enhancing hollow SnO 2 anode performance for Li-ion batteries

Abstract

A composite anode consisting of hollow SnO2 microspheres covered by glass-like B2O3 layers was prepared via a combined hydrothermal-impregnation method, which results in much improved electrochemical performance in lithium ion batteries, relative to pristine SnO2 anodes. The cycling and rate capabilities of the SnO2-B 2O3 composite anodes were investigated as a function of B2O3 content. The balance between increased electron-acceptor effect and compromised electronic conductivity due to addition of B2O3 is maximized around 20 wt% B2O 3 loading. The best performing SnO2-B2O 3 composite anode exhibits a specific capacity of 622.7 mAh g -1 up to 160 cycles, and is able to maintain a capacity above 528.6 mAh g-1 at rate of 5C. These enhanced performance characteristics are attributed to the unique composite structures consisting of the hollow SnO 2 cores and the B2O3 buffer layers, which likely are beneficial for reducing the overall volume changes. Importantly, the decreased charge transfer resistance and increased Li+ diffusion coefficient, resulting from B2O3 coating, lead to overall improvement of rate performance for the composite anodes. Such-fabricated composite structures are stable during the Li+ insertion/extraction, thereby promoting cycling stability. © 2013 Elsevier B.V. All rights reserved.