Boosting Sodium Storage in TiO2 via Synchronous Surface Sulfurization and Amorphization

Abstract

The poor conductivity and slow ion diffusion of anatase TiO2 hinder its application in sodium-ion batteries. To overcome this, we construct a sulfur-doped amorphous surface layer (~1 nm) on TiO2 via low-temperature gas-phase vulcanization. This design, verified by DFT and experiment, simultaneously narrows the bandgap and creates fast ion channels. The resulting S-TiO2 anode achieves a high capacity of 170 mAh g⁻¹ after 200 cycles at 0.5 C and superior rate performance (105 mAh g⁻¹ at 8 C). This work provides an effective surface engineering strategy, termed “sulfur-driven amorphization,” for activating metal oxide anodes.