Nitrogen-treated Hierarchical Macro-/Mesoporous TiO₂ Used as Anode Materials for Lithium Ion Batteries with High Performance at Elevated Temperatures

Abstract: In this article, we employed nitrogen gas treatment as an effective strategy in caclination to significantly improve the performance of hierarchical macro-/mesoprous TiO₂ as anode materials for lithium ion batteries at an elevated temperature of 55 °C. Room-temperature synthesized macro-/mesoprous TiO₂ was calcined under nitrogen and air conditions at 300 °C for 3 h, respectively. The specific surface area was studied by nitrogen adsorption/desorption measurement and the surface chemistry was studied by X-ray photoelectron spectroscopy (XPS). It was found that the macro-/mesoprous TiO₂ had a specific surface area of 330 m² g⁻¹ after calcination under nitrogen atmosphere, while only 248 m² g⁻¹ after calcination under air atmosphere. Electrochemical tests showed that, in comparison to air-treated TiO₂, nitrogen-treated TiO₂ exhibited considerable high capacity and good rate performance as a lithium ion battery anode at the elevated temperature (55 °C). It had a capacity of 293 mAh g⁻¹ after 50 cycles at mixed current densities of 30, 150, and 500 mA g⁻¹, while the air-treated TiO₂ only had a capacity of 187 mAh g⁻¹ after 50 cycles. This improvement of lithium ion storage capability can be ascribed to the nitrogen-treatment effect on crystallinity and the presence of surface defects on TiO₂ nanostructure