Electron transport mechanism of tungsten trioxide powder thin film studied by investigating effect of annealing on resistivity

•Electron conduction mechanism of tungsten trioxide (WO3) was studied.•N2 annealing was found to decrease the resistivity of WO3.•WO3 thin film was fabricated by necking nanoparticles using spray processes.

We report a new approach for improving the recharging and discharging speed of lithium ion batteries based on understanding of the electron conduction mechanism of tungsten trioxide (WO3) powder thin films fabricated from nanoparticles and used in lithium ion battery electrodes. Resistivity measurements are carried out after annealing in N2 or 5% O2 + 95% N2 ambient. Annealing in N2 ambient decreases the resistivity owing to the increased number of oxygen vacancies in the WO3 thin film. Fitting results obtained from the resistivity are used to propose the simultaneous existence of two types of electron conduction mechanism, band conduction and nearest-neighbor hopping (NNH) conduction, contributing to electron conduction in WO3 thin films.