Characterization of MoO3-x thin films

Solid state thin film batteries With MoO3-(x) films as their cathode active material exhibit good battery performance. The chemical composition Of the MoO3-x thin film has been difficult to determine by chemical analysis, because of the difficulty in weighing ultra light samples located on massive substrates. To surmount this problem, we fabricated fairly thick MoO3-x films and used thermal analysis to examine the MoO3-x samples peeled from substrates. The weight change observed after complete oxidation suggested that the chemical composition Of MoO3-x is MoO2.69. The thermal analysis and X-ray diffraction results showed that the MoO3-x film did not have a single phase but had mixed phases and we believe that the main and second phases are Mo9O26 and MoO2, respectively. The presence Of MoO2 provides the film with high electrical conductivity and good cathode performance. Scanning electron microscope (SEM) observation of the film surface showed that the grain size was 20-100 nm and that the film had high density.