Nitrogen-doped TiO2(B) nanobelts enabling enhancement of electronic conductivity and efficiency of lithium-ion storage

Abstract

To enhance the intrinsic electrical conductivities of TiO2(B) nanobelts, nitrogen(N)-doped TiO2(B) nanobelts (N-TNB) were prepared in this study by a facile and cost-effective hydrothermal method using urea as the nitrogen source with TiO2 (P25) nanoparticles. x-ray photoelectron spectroscopy confirmed that the N-atoms preferentially occupied up to ∼0.516 atom% in the interstitial sites of the N-TNB and the maximum concentration of substituted-N bonds in the N-TNB was ∼0.154 atom%, thereby the total concentration of doped nitrogen elements of ∼0.67 atom% improved the high intrinsic electrical conductivity and ionic diffusivity of the TiO2(B) nanobelts. The as-prepared N-TNB electrode delivered the highest specific capacity of 133.9 mAh g−1 in the first cycle, with an exceptional cyclic capacity retention at an ultrafast current rate of 1000 mA g−1; this is not less than 51% after 500 cycles and represents an excellent rate capability of ∼37 mAh g−1 at an ultra-high rate of 40 C. These values are among the best ever reported on comparison of the delivered highest discharge capacity of N-TNB at 1000 mA g−1 and high-rate capabilities of its Li+ ion storage with the literature data for N-TNB (∼231.5 mAh g−1 at a very low current density of 16.75 mA g−1, ∼0.1 C) of similar materials used in sodium-ion batteries. This implies the potential feasibility of these N-TNB as high-capacity anode materials for next-generation, high-energy-density, electrochemical energy-storage devices.