Improved electrochemical performance of SBA-15 based SiO2 anodes with N-doping porous carbon

Abstract

Silica is an alternative to silicon-based anodes for low-cost and large-scale applications of lithium-ion batteries. However, the low capacity and poor rate capability faced by SiO2-based anodes are still the main bottlenecks to further development. Here we report a uniform encapsulation of N-doping porous carbon on the silica SBA-15 ([email protected]), fabricated by a freeze drying synthesis method, and used as anode materials for lithium-ion batteries. It gives a high capacity of ∼720 mAh/g at 100 mA g−1, and a rate capability up to 800 mA g−1 delivering capacity of ∼450 mAh/g, as well as cycle stability beyond 200 cycles. The improved electrochemical performance is owing to the rapid lithium ion diffusion in the fabricated [email protected] composite, and abundant sites of electrochemical activity provided by nitrogen doping that manipulate local electronic structure, as well as good electrical transport from porous carbon. This work explores the Li+ ions transfer and diffusion kinetics in N-doping SiO2-C composite and the intrinsic electrochemical reaction mechanism, providing future direction for improving SiO2-based anodes.