Dual confinement of carbon/TiO2 hollow shells enables improved lithium storage of Si nanoparticles

Abstract

Silicon is regarded as one of the most promising anode materials for next generation lithium-ion batteries (LIBs). However, the severe volume changes during lithiation/delithiation, leading to fast capacity decay and reduced cycling life, remains an obstacle to its practical application. In this work, we propose the design of a yolk-shell structure of carbon@TiO2@Si (CTS) by template process based on sol-gel chemistry. The Si nanoparticles are confined in the carbon/TiO2 double shells with abundant void space between the Si core and carbon/TiO2 shells. The yolk-shell architecture with concentric double shells substantially improves the structure stability of the electrodes. Consequently, the CTS delivers a high capacity of 747 mA h g−1 at a current density of 100 mA g−1, which is far superior to that (356 mA h g−1) of C@Si (CS) with only a single carbon shell. The double-shelled confinement strategy proposed in this work sheds some light on the development of improved Si-based anode for next-generation LIBs.