Controllable oxygen vacancy SnO2-x anodes for lithium-ion batteries with high stability

Abstract

Oxygen vacancy is crucial for improving the electrochemical performance of conversion-alloying anodes in lithium-ion batteries. The introduction of oxygen vacancies considerably enhances the reversibility of conversion reaction. However, the mechanism of improving the stability of such anodes still requires further exploration. Herein, ultrafine SnO2-x nanoparticles (NPs) with tunable oxygen vacancy content are successfully synthesized via an in-situ flame process. The oxygen-vacancy content can regulate the proportion of conversion reaction, thereby realizing a high-stability anode. Consequently, pure SnO2 anodes without carbon matrix hybrid exhibit excellent rate capacity (307.8 mAh g−1 at 10 A g−1) and considerable long-term stability (887.1 mAh g−1 at 1 A g−1 after 1000 cycles). Moreover, the synthesized NPs are directly mixed with commercial graphite to achieve composite anodes, which show high specific capacities of 640.7 and 965.6 mAh g−1 (20 and 40 wt% SnO2-x NPs) at 0.1 A g−1. A full cell assembled using commercial NCM811 as the cathode exhibited a high energy density of 663.3 Wh kg−1 at 1 A g−1 based on the total active mass of the cathode and anode.