Nitrogen-Doped TiO₂–C Composite Nanofibers with High-Capacity and Long-Cycle Life as Anode Materials for Sodium-Ion Batteries

Abstract: Nitrogen-doped TiO₂–C composite nanofibers (TiO₂/N–C NFs) were manufactured by a convenient and green electrospinning technique in which urea acted as both the nitrogen source and a pore-forming agent. The TiO₂/N–C NFs exhibit a large specific surface area (213.04 m² g⁻¹) and a suitable nitrogen content (5.37 wt%). The large specific surface area can increase the contribution of the extrinsic pseudocapacitance, which greatly enhances the rate capability. Further, the diffusion coefficient of sodium ions (D_Na+) could be greatly improved by the incorporation of nitrogen atoms. Thus, the TiO₂/N–C NFs display excellent electrochemical properties in Na-ion batteries. A TiO₂/N–C NF anode delivers a high reversible discharge capacity of 265.8 mAh g⁻¹ at 0.05 A g⁻¹ and an outstanding long cycling performance even at a high current density (118.1 mAh g⁻¹) with almost no capacity decay at 5 A g⁻¹ over 2000 cycles. Therefore, this work sheds light on the application of TiO₂-based materials in sodium-ion batteries.[Figure not available: see fulltext.].