In Situ Fabrication of Branched TiO₂/C Nanofibers as Binder-Free and Free-Standing Anodes for High-Performance Sodium-Ion Batteries

Herein, 1D free-standing and binder-free hierarchically branched TiO₂/C nanofibers (denoted as BT/C NFs) based on an in situ fabrication method as an anode for sodium-ion batteries are reported. The in situ fabrication endows this material with large surface area and strong structural stability, providing this material with abundant active sites and smooth channels for fast ion transportation. As a result, BT/C NFs with the character of free-standing membranes are directly used as binder-free anode for sodium-ion batteries, delivering a capacity of 284 mA h g⁻¹ at a current density of 200 mA g⁻¹ after 1000 cycles. Even at a high current density of 2000 mA g⁻¹, the reversible capacity can still achieve as high as 204 mA h g⁻¹. By means of kinetic analysis, it is demonstrated that the remarkable surface pseudocapacitive behavior is also a major factor to achieve excellent performance. The rationally designed structure coupled with the inherent pseudocapacitive behavior gives this material potential for sodium-ion batteries.