Silica/Carbon Composites with Controllable Nanostructure from a Facile One‐Step Method for Lithium‐Ion Batteries Application

Abstract

Abstract Nanosized silica is drawing attentions in lithium‐ion batteries because of its better cycling stability and lower cost compared to silicon. However, significant challenges appear at the uncontrollable and inhomogeneous nanostructure while coupling silica with carbon. Herein, a series of silica/carbon (S/C) composites with tunable nanostructure are developed based on the mechanism that hydrofluoric acid (HF) can control the gelating process of tetraethylorthosilicate (TEOS). By changing the HF/TEOS ratio, the size of the silica skeleton, surface area and porosity of the composites can be tailored precisely. As a result, the optimal lithium storage performance is obtained on the S/C composite with a silica size of ≈9 nm, surface area of 208 m 2 g −1 , and total pore volume of 0.24 cm 3 g −1 , including a specific capacity of 820 mAh g −1 , superior cycling performance, and high‐rate capability. This can be attributed to the following reasons: 1) the suitable silica size of ≈9 nm simultaneously minimizes the Li + migrating distance while maintaining the stability of the silica skeleton; 2) the rigid continuous carbon framework acts as a conductive skeleton and restricts the aggregation and volume change of the silica; 3) the porous structure plays roles in buffering the volume change and facilitating the electrolyte transfer.