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

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.