Nano/micro-structured Si/CNT/C composite from nano-SiO2 for high power lithium ion batteries

Abstract

Nano/micro-structured pSi and pSi/CNT particles were synthesized from nano-SiO₂ as both a template and silicon precursor via a combination of spray drying and magnesiothermic reduction, followed by a nano-layer carbon coating by chemical vapor deposition to obtain a nano/micro-structured pSi/C and pSi/CNT/C composite. In the hierarchical microstructure of the pSi/CNT/C composite, Si nanoparticles less than 20 nm in size were homogenously dispersed in an electronically conductive and porous network of multiwall carbon nanotubes, which can accommodate the volume changes in Si and improve the structural and conductive stability during repeated cycles leading to excellent electrochemical performance. The pSi/CNT/C presented reversible capacities of ca. 2100 mA h g⁻¹ at 1 A g⁻¹ and ca. 1370 mA h g⁻¹ at a high current rate of 5 A g⁻¹. Its capacity retention after 100 cycles was 95.5% at 1 A g⁻¹.