Boron-doped porous Si anode materials with high initial coulombic efficiency and long cycling stability

Abstract

Silicon is regarded as a promising next-generation anode material to replace carbon-based materials in lithium–ion batteries. However, the poor conductivity and dramatic volume changes of Si anode materials lead to their low initial coulombic efficiency and unsatisfactory cycling stability. Herein, highly crystalline B-doped porous Si (B-doped pSi) nanoplates were designed and prepared via the air-oxidation demagnesiation of Mg₂Si from p-type Si wafers. Doping with B greatly decreased the resistance and surface oxidation compared to the raw materials, and the high-temperature synthetic process resulted in high crystallinity. As a result, the obtained material exhibits a high initial coulombic efficiency of 89% and a superior rate capability of 1107 mA h g⁻¹ at 6.4 A g⁻¹. Furthermore, the unique porous plate-like structure provides free space for the volumetric expansion of Si, which results in good cycling performance (reversible capacity of 1500 mA h g⁻¹ at 2 A g⁻¹ after 300 cycles) in the B-doped porous Si.