Controlled synthesis of mesoporous Si/C composites anode via confining carbon coating and Mg gas reduction

The application value of silicon-based anodes has not been fully realized due to the ∼ 300% volume expansion and poor electronic conductivity. In present study, mesoporous Si/C (MP-Si/C) composite with nanosized primary particles of 30-50 nm and pore diameter of 20-40 nm was proposed, which displays superior Li storage properties. Firstly, Polyacrylic acid (PAA) was applied to fulfill in-situ carbon coating and inhibit the particle growth of SiO2 generated from tetraethyl orthosilicate (TEOS) in stöber reaction. Secondly, Mg gas was introduced to create nano-sized Si with meso-pores and three-dimensional carbon network via the gas-cutting effect. The cycling stability and rate capability were both significantly enhanced with capacity of 671 mAh/g after 400 cycles and 593 mAh/g after 500 cycles at 2 A/g and 4 A/g, respectively, which was highly relevant to the selection of carbon source PAA and its corresponding carbon coating and Mg reduction effect. Moreover, this method bypasses the use of costly nano-silicon, which provides inspiration for the commercialization of silicon-based anodes.