Tunnel‐Type Na2Ti6O13@Carbon Nanowires as Anode Materials for Low‐Temperature Sodium‐Ion Batteries.

Economical efficient anode materials play an important role in low‐temperature sodium‐ion batteries (SIBs). Tunnel‐type structured Na2Ti6O13@C nanowires were synthesized and utilized as anode material for low‐temperature SIBs. The appropriate interlayer spacing for sodium ion insertion and short diffusion pathway can accelerate the sodium ion kinetics and decrease the apparent activation energy at low temperature. The diffusion apparent activation energy and activation energy for Na2Ti6O13@C were calculated to be 42.0 kJ mol−1 and 15.3 kJ mol−1 with the sodium ion diffusion coefficients about 10−12 cm2 s−1. The Na2Ti6O13@C nanowires exhibit a high reversible capacity of 100 mAh g−1 at 0 °C with 99.6 % retention after 200 cycles at 0.5 C. Coupling with the sodium vanadium phosphate as cathode, the assembled Na2Ti6O13@C||NVP full‐cell can keep a 65 % capacity retention after 175 cycles at 0 °C. This work presents that Na2Ti6O13@C nanowires can be an ideal type of anode active materials for low‐temperature SIBs. [ABSTRACT FROM AUTHOR]