Irena Kozjek Škofic, Nataša Bukovec
Faculty of Chemistry and Chemical Technology, University of Ljubljana, Aškerčeva 5, 1001 Ljubljana, Slovenia
Thin films of Ce-V mixed oxides with Ce/V molar ratios equal to 4 or 2 were prepared on SnO2/F covered glass by the sol-gel dip-coating process using CeCl3 × 7H2O and NH4VO3 as precursors. The films were heat-treated in an air or argon atmosphere. The electrochemical and optical properties depend on the mode of preparation. The influence of the composition and preparation of the sols as well as annealing conditions (atmosphere, temperature and time) on the optical and electrochemical characteristics of the films were studied. Ce-V mixed oxide films annealed in an argon atmosphere have better electrochemical behaviour than films annealed in an air atmosphere. As expected, the ion-storage capacity increased with increasing content of vanadium species in the films and reached the value of 23.9 mC cm–2 at a Ce/V molar ratio of 2 (after the 20th cycle), with notable cycling stability (Qi/Qe = 0.98 after the 100th cycle) when heat-treated in an argon atmosphere. All the films are optically passive under charge insertion and have a high transmittance (> 90%) in the visible range.