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

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 (DNa+) 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.