Dual stabilized architecture of hollow Si@TiO2@C nanospheres as anode of high-performance Li-ion battery

Abstract

The hollow Si nanospheres modified by the mechanically robust titanium dioxide (TiO2) shell and the uniform carbon layer are intentionally designed and successfully prepared as the anode active material of high performance lithium-ion batteries. The effects of the robust TiO2 shell and the uniform carbon layer on the structure and electrochemical performances for the Si@TiO2@C nanospheres are studied in detail by X-ray photoelectron spectroscopy, transmission electron microscopy, X-ray diffraction and charge/discharge tests. The results show that the hollow structure of the Si core can spontaneously absorb the huge volume expansion stress, the robust TiO2 shell is used as a compact fence to promote the expansion towards the interior of the Si cavity instead of the exterior in the processes of charge/discharge, and the uniform carbon layer can effectively enhance the electrical conductivity and further control the integrity and stability of the well-wrapped core-shell-shell framework. Typically, the resultant hollow Si@TiO2@C nanospheres exhibit a high initial discharge capacity of 2557.1 mAh g−1 with coulombic efficiency of 86.06% as well as a large recuperative discharge capacity of 1270.3 mAh g−1 after 250 cycles at 1 A g−1 with a mean coulombic efficiency of 99.53%. Therefore, the hollow Si@TiO2@C nanospheres prepared by one-step sol-gel coating process show outstanding electrochemical properties and are considered as a prospective candidate to the adhibitions of the anode material for new generation power LIBs.