T‐Nb2O5/C Nanofibers Prepared through Electrospinning with Prolonged Cycle Durability for High‐Rate Sodium–Ion Batteries Induced by Pseudocapacitance

Abstract

Homogeneous ultrasmall T‐Nb₂O₅ nanocrystallites encapsulated in 1D carbon nanofibers (T‐Nb₂O₅/CNFs) are prepared through electrospinning followed by subsequent pyrolysis treatment. In a Na half‐cell configuration, the obtained T‐Nb₂O₅/CNFs with the merits of unique microstructures and inherent pseudocapacitance, deliver a stable capacity of 150 mAh g⁻¹ at 1 A g⁻¹ over 5000 cycles. Even at an ultrahigh charge–discharge rate of 8 A g⁻¹, a high reversible capacity of 97 mAh g⁻¹ is still achieved. By means of kinetic analysis, it is demonstrated that the larger ratio of surface Faradaic reactions of Nb₂O₅ at high rates is the major factor to achieve excellent rate performance. The prolonged cycle durability and excellent rate performance endows T‐Nb₂O₅/CNFs with potentials as anode materials for sodium‐ion batteries.