Facile synthesis of uniform MWCNT@Si nanocomposites as high-performance anode materials for lithium-ion batteries

Highlights: • A uniform SiO₂ layer was deposited on multi-walled carbon nanotube. • Synthesis of uniform (MWCNT)@Si nanocomposites via the magnesiothermic reduction. • The MWCNT@Si nanocomposites show high reversible capacity and good cyclability. • Enhanced performance is attributed to porous nanostructure, introduction of MWCNTs. - Abstract: We demonstrate the synthesis of uniform multi-walled carbon nanotube (MWCNT)@Si nanocomposites via the magnesiothermic reduction of pre-synthesized MWCNT@SiO₂ nanocables. At first, the acid vapor steaming is used to treat the surface, which can facilitate the uniform deposition of SiO₂ layer via the TEOS hydrolysis. Then, the uniform MWCNT@Si nanocomposites are obtained on the basis of MWCNT@SiO₂ nanocables via a simple magnesiothermic reduction. When used as an anode material for lithium-ion batteries, the as-synthesized MWCNT@Si nanocomposites show high reversible capacity and good cycling performance, which is better than bulk Si and bare MWCNTs. It is believed that the good electrochemical performance can be attributed to the novel porous nanostructure and the introduction of MWCNTs that can buffer the volume change, maintain the electrical conductive network, and enhance the electronic conductivity and lithium-ion transport