T‐Nb 2 O 5 /C Nanofibers Prepared through Electrospinning with Prolonged Cycle Durability for High‐Rate Sodium–Ion Batteries Induced by Pseudocapacitance

Homogeneous ultrasmall T‐Nb 2 O 5 nanocrystallites encapsulated in 1D carbon nanofibers (T‐Nb 2 O 5 /CNFs) are prepared through electrospinning followed by subsequent pyrolysis treatment. In a Na half‐cell configuration, the obtained T‐Nb 2 O 5 /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 Nb 2 O 5 at high rates is the major factor to achieve excellent rate performance. The prolonged cycle durability and excellent rate performance endows T‐Nb 2 O 5 /CNFs with potentials as anode materials for sodium‐ion batteries.