Boosting sodium storage in TiO2via 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 through DFT and experiments, 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 0.5C and superior rate performance (105 mAh g⁻¹ at 8C). This work provides an effective surface engineering strategy, termed “sulfur-driven amorphization,” for activating metal oxide anodes.