Synergistic Regulation of Nitrogen-Doped Carbon Coating and Pseudocapacitive Kinetics in TiO2 Nanofibers for Enhanced Sodium-Ion Storage

Sodium-ion batteries (SIBs) represent a compelling alternative to lithium-ion batteries for grid-scale energy storage, owing to the high natural abundance and low cost of sodium resources, as well as their strategic alignment with national energy security priorities. Nevertheless, the sluggish Na+ diffusion kinetics and limited specific capacity of anode materials continue to impede practical deployment. Herein, nitrogen-doped carbon-coated TiO2 nanofibers (TiO2/C-N) were rationally engineered through a facile electrospinning route integrated with synergistic defect and coating engineering. The in situ-formed N-doped carbon shell establishes a continuous, high-conductivity electron-transport network while simultaneously buffering volumetric strain during repeated (de)sodiation, thereby preserving long-term structural integrity. Electrochemical assessments demonstrate that the TiO2/C-N electrode delivers a reversible specific capacity of 233.64 mAh g−1 at 0.1 A g−1 (initial Coulombic efficiency 54.13%). Quantitative kinetic analysis reveals a pronounced pseudocapacitive contribution of 41.4% at 1.2 mV s−1, confirming a surface-controlled Na+ storage pathway that markedly enhances rate capability. Moreover, the electrode retains 245.5 mAh g−1 after 150 cycles at 1 A g−1, underscoring exceptional cycling stability. This work elucidates the synergistic regulation of N-doped carbon coating and pseudocapacitive kinetics in TiO2-based anodes, offering a robust design strategy for high-rate, long-cycle-life SIB anodes.