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.