Amorphous TiO_2 layer on silicon monoxide nanoparticles as stable and scalable core-shell anode materials for high performance lithium ion batteries

摘要

SiOx (0 x 2) based materials are attractive for developing high-capacity and durable anodes toward superior lithium storage. Herein, low cost and tailorable core-shell SiO@TiO2 nanocomposites have been synthesized via simple ball milling and sol-gel process. The designed nanocomposite is composed of nano-sized SiO as the inner core and amorphous TiO2 layer as the shell. Remarkably, when used as anode material for lithium ion batteries, the SiO@TiO2 exhibits greatly enhanced capacity performance and cycling stability due to its rational core-shell structure. The optimal nanocomposite delivers a high initial specific capacity of 1920 mA h g(-1) with high initial coulombic efficiency of 79.4%, along with a stable reversible capacity of 901 mA h g(-1) after 200 cycles at 200 mA g(-1) and impressive high-rate capacity of 272 mA h g(-1) at 3000 mA g(-1). The excellent electrochemical performance of the nanocomposite is contributed by the synergetic core-shell structure, in which the amorphous TiO2 shell can not only act as protective/elastic buffer layer to accommodate the volume change of the SiO nanoparticles upon cycling, but also largely favor the Li+ diffusion in the nanocomposite toward highly reversible lithium storage. In virtue of the simple, green and scalable fabrication process, these robust and efficient nanocomposites are promising to realize inexpensive and high-performance lithium ion batteries anodes and related energy storage applications.