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

摘要

The core-shell structural N-doped carbon encapsulating Si@TiO2 composite (Si@TiO2/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@TiO2/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@TiO2 and Si/NC materials when the composite materials are used as anodes for lithium-ion batteries, in which the Si@TiO2/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 200mA g(-1), extraordinary rate and cycle capability with the charge specific capacity of 696.2 mAh g(-1) under the test current of 3000mA 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 TiO2 skeleton and the elastic conductive N-doped carbon network, indicating the as-prepared Si@TiO2/NC composite could be a promising anode for lithium-ion batteries. (c) 2019 Elsevier Ltd. All rights reserved.