Improving the lithium storage performance of micro-sized SiOx particles by uniform carbon interphase encapsulation and suitable SiO2 buffer component

Abstract

Silicon anode material has a high specific capacity for high-energy-density lithium-ion batteries, but the pulverization issue during cycling has limited its cycle life in the practical application. Herein, we demonstrate a micro-sized SiOx/C composite with an average particle size of 1.12 µm, suitable SiO2 content and uniform carbon encapsulation as a potential anode material for lithium-ion storage. The residual SiO2 component, which is carefully tuned by changing the amounts of hydrofluoric acid, severs as a buffer layer to alleviate the volume change of active Si particles and maintain the structural integrity. Furthermore, the encapsulated carbon component inside and outside the SiOx rather than isolated surface coating can greatly increase the electronic conductivity, cycle stability and reaction reversibility of Li-ions storage. As a result, the designed SiOx/C composite as an anode exhibits a high initial coulombic efficiency of 78.2 % with a high reversible capacity of 2298 mAh g−1, stable cycle performance with more than 716 mAh g−1 over 300 cycles and impressive rate capability (786 mAh g−1 at 2000 mA g−1). The SiOx/C hybrid anode demonstrates the importance of the SiO2 buffer matrix and carbon location in Si-based anode materials for developing high-energy-density and long-life lithium-ion battery.