Low-temperature fabrication of porous SiO with carbon shell for high-stability lithium ion battery

Abstract

Porous silicon monoxide (p-SiO) is one of the most promising anode materials for lithium-ion batteries because it possesses high theoretical capacity and small volume expansion. Traditionally, SiO is prepared at 1200 °C, which restrains the application of SiO materials due to its high consumption of energy. Herein, a low-temperature synthesis process of p-SiO at 650 °C is developed from a controllable magnesiothermic reduction of porous silica. Compared with normally reduced solid silica (SiO2@SiO), p-SiO is fabricated more easily from porous SiO2 due to the improved contact between SiO2 and Mg atom. Moreover, high porosity of p-SiO facilitates the growth of carbon shell, making p-SiO@C with remarkable electrochemical properties. The reversible capacity for p-SiO@C (839.6 mA h g−1, at 500 mA g−1) is about two times that for SiO2@SiO@C (426.4 mA h g−1, at 500 mA g−1) after 110 cycles, and the synergetic properties of p-SiO@C further presents good cycling stability (777.1 mA h g−1, at 500 mA g−1 after 300 cycles) and excellent rate capability (977 mA h g−1, at 1000 mA g−1). The low-temperature fabrication of p-SiO followed by carbonization is promoting for practical application in high-performance Si-based lithium-ion battery.