An insight of sodium-ion storage, diffusivity into TiO2 nanoparticles and practical realization to sodium-ion full cell

Abstract

To improve the charge storage and kinetics of TiO2 anodes for sodium-ion batteries, a hybrid material of TiO2 nanoparticles is build-in onto multiwall carbon nanotube. The cycling stability and C-rate performance of carbon nanotube -TiO2 hybrid as anodes for sodium-ion batteries demonstrate two and half times enhancement in electrochemical performance in the presence of carbon nanotube. The hybrid shows discharge capacity of 100 mAh g−1 at a current density of 1 Ag-1, stable for 1000 cycles with little capacity fade. The overall charge storage properties of pristine TiO2 and carbon nanotube-TiO2 hybrid is due to pseudocapacitive and diffusion-control Na+ intercalation. Two times increase in Na+ diffusivity in carbon nanotube-TiO2 hybrid is achievable in relation to pristine TiO2. The superb electrochemical performance is due to the synergetic effect of TiO2 nanoparticles and conducting carbon nanotube network which provides efficient charge storage and Na+ diffusivity. Finally, the realization of practical sodium-ion full cells by using carbon nanotube -TiO2 hybrid as anode and F-containing vanadium phosphate cathode which deliver a capacity of 184 mAh g−1 at a current density of 30 mAg−1. This work is the fundamental understanding of Na+ storage, the kinetics of the TiO2 electrode and its practical realization in sodium-ion full cell.