Enhanced lithium storage performance of core-shell structural Si@TiO2/NC composite anode via facile sol-gel and in situ N-doped carbon coating processes

The core-shell structural N-doped carbon encapsulating Si@TiO 2 composite (Si@TiO 2 /NC) are prepared by facile sol-gel, polymerization of dopamine hydrochloride and the following heat treatment processes, which are confirmed by the scanning electron microscopy, X-ray diffractometer, transmission electron microscopy , X-ray photoelectron spectroscopy and thermogravimetric analyses. The as-prepared Si@TiO 2 /NC composite present favorable spherical shape with about 150 nm in diameter and uniform element distribution, and demonstrate the enhanced electrochemical properties compared to the pure silicon , Si@TiO 2 and Si/NC materials when the composite materials are used as anodes for lithium-ion batteries, in which the Si@TiO 2 /NC composite anodes display the favorable initial coulombic efficiency of 75.9%, remarkable charge specific capacity of 1070.9 mAh g −1 with the coulombic efficiency approaching 100% after 100 cycles under the test current of 200 mA g −1 , extraordinary rate and cycle capability with the charge specific capacity of 696.2 mAh g −1 under the test current of 3000 mA g −1 and increased lithium ion diffusion coefficient from 8.179 E-12 cm 2  s −1 to 8.995 E-12 cm 2  s −1 after 100 cycles. Those excellent electrochemical properties can be attributed to the synergistic effect of the robust TiO 2 skeleton and the elastic conductive N-doped carbon network, indicating the as-prepared Si@TiO 2 /NC composite could be a promising anode for lithium-ion batteries.