Nitrogen-doped TiO2 nanotube anode enabling improvement of electronic conductivity for fast and long-term sodium storage

Abstract Titanium oxide has recently drawn much attention as anode material for sodium ion batteries. Nevertheless, its application is highly restricted by poor electronic conductivity and sluggish Na+ reaction kinetics. Herein, we report nitrogen(N)-doped-TiO2 nanotubes (N-TiO2-NTs) through a facile and cost-effective anodization process and annealing at NH3/Ar flow. XPS analysis investigates that the ratio of doped N element is 2.1 at% mainly in interstitial sites, which can effectively improve intrinsic electronic conductivity and enhance Na+ diffusivity of the TiO2 bulk. Due to the hetero-N doping and high specific area of nanotube structure, the kinetic activity of N-TiO2-NTs is observably enhanced. Therefore, the anode delivers high capacitive-controlled behaviors up to 80.3% and 86% of whole capacities at scanning rates of 0.6 and 1 mV s−1. The N-TiO2-NTs anode exhibits good and stable capacity (216.1 mA h g−1 at 0.2 C after 300 cycles) and high rate performance (114 mA h g−1 at 20 C). Moreover, the long-term cycling test after 5000 cycles obtains nearly 100% capacity retention at an ultrahigh current density of 10 C. Thus, we offer a facile strategy to develop N-TiO2-NTs as a hopeful product for the anode materials in sodium ion batteries.