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

摘要

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.