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 m2g-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-1at 0.05 A g-1and an outstanding long cycling performance even at a high current density(118.1 m Ah g-1) with almost no capacity decay at 5 A g-1over 2000 cycles. Therefore, this work sheds light on the application of TiO2-based materials in sodium-ion batteries.