Double core-shell of Si@PANI@TiO2 nanocomposite as anode for lithium-ion batteries with enhanced electrochemical performance

Abstract

A unique double core-shell structure of Si@PANI@TiO2 nanocomposite is synthesized by a simple in-situ growth method. The two shells of polyaniline (PANI) and TiO2, hand in hand, play a key role to improve the electrochemical performance: First, the flexible properties of polyaniline (PANI) effectively accommodate the volume change of Si during the cycling. Second, the good mechanical feature of TiO2 can maintain the structural integrity and attenuate the volume expansion of Si cores. Finally, both of polyaniline and the lithiated TiO2 enhance the conductivity of Si, which promotes the electrons transport. Resulting in the Si@PANI@TiO2 double core-shell nanocomposite exhibits remarkable synergy in large, reversible lithium storage, delivering a reversible capacity as high as 1027 mAh g−1 after 500 cycles and a superior rate capacity of 640 mAh g−1, at a current of 500 and 4000 mA g−1, respectively. This excellent cycling and high-rate capability can be ascribed to the unique and well-designed double core-shell structure with the synergistic effect between polyaniline (PANI) and TiO2.