Comparative study of electrical parameters and Li-ion storage capacity of PEG modified β-V₂O₅:M (M: Mo, Ni) thin films

We report the comparative investigation of Mo and Ni incorporation effects on the electrochemical behavior, DC conductivity and optical transmittance of PEG/β-V₂O₅ thin films. Mo doping, changed the preferred orientation of tetragonal structure from (241) to (200) direction, while Ni doping had no considerable effect on the texture coefficient of pristine V₂O₅. Moreover, the highest electrical conductivity observed in PEG/V₂O₅:Mo sample could be related to the substitution of V⁵⁺ by Mo⁶⁺. This substitution increased electrical carrier concentration (3.7E19 cm⁻³) which led to the enhancement of electrical conductivity. Because of that, a significant improvement has been occurred in the electrochemical behavior of PEG/V₂O₅:Mo film. According to the results, the specific capacitance and the charge transfer resistance of PEG/V₂O₅:Mo thin films were found to be almost 5 times higher and less than half of pure V₂O₅ film, respectively. In addition, FESEM images showed that PEG/V₂O₅:Ni sample had nanoflaked surface morphology with dispersed nanograins, whereas the PEG/V₂O₅:Mo sample exhibited a special porous morphology with stacked nanograins distributed on striped sheets. Based on optical measurements, Mo doping also boosts the average transmittance of the PEG/V₂O₅ sample. Besides, the observed blue shift in the absorption edge of the doped samples could be attributed to the Burstein-Moss effect.