Mitigation of Volume Expansion of Silica Anodes by Porous Titanium Dioxide Coating for Lithium-Ion Batteries.

Silica (SiO₂) is one of the most promising anode materials for LIBs due to its high theoretical capacity. However, the huge volume change of silica during the lithiation/delithiation processes is a disadvantage that results in poor electrochemical performance. In this study, the volume change of silica was effectively mitigated by coating the SiO₂ anode with porous TiO₂. The porous TiO₂ has a large amount of internal space that can mitigate the volume expansion of SiO₂. To verify the ratio of the volume change, the crosssection of the electrodes was analyzed by scanning electron microscopy (SEM). The ratio of the volume change decreased from 293.5% to 140.7% upon application of the TiO₂ coating. Fourier transform infrared analysis suggested that the Ti-O-Si bond helped mitigate the volume expansion. Furthermore, the decrease in the volumetric expansion resulted in good electrochemical performance with increased charge capacity and stable cycle performance. The TiO₂ coated SiO₂ anode displayed a capacity of 72.33 mA h g at a current density of 98 mA g for up to 50 cycles, which was higher than that of the pristine SiO₂ anode (42.29 mA h g). The TiO₂ coated anode materials are applicable for rechargeable lithium-ion batteries.