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Structural Analysis Using Synchrotron XRD and XAFS for Cobalt Oxyhydroxides Heat-Treated under Sodium Hydroxide Solution for Nickel Hydroxide Electrode

2009; Institute of Physics; Volume: 156; Issue: 5 Linguagem: Inglês

10.1149/1.3079421

1945-7111

Masanori Morishita, Seijiro Ochiai, Tadashi Kakeya, Tetsuya Ozaki, Yoshiteru Kawabe, Masaharu Watada, Tetsuo Sakai,

Catalytic Processes in Materials Science

The structural analysis for the cobalt oxyhydroxide has been done by using high-energy synchrotron X-ray diffraction (XRD) and X-ray absorption fine structure (XAFS) analysis. The relationship between the structure and the electrical conductivity for cobalt oxyhydroxide was investigated. The structural refinement for cobalt oxyhydroxide heat-treated in the temperature range of has been done successfully on the basis of two phase models (L and S phase) with large and small lattice constants. With increasing treatment temperature, the phase abundance for the L phases was increased, whereas the one for the S phases was decreased. By heat-treatment above , the cobalt ions for the cobalt oxyhydroxide were oxidized to the higher oxidation state over 3. The electrical resistivity was extremely decreased by treatment temperatures above . The increase in the electrical conductivity for the cobalt oxyhydroxide could be explained by the increase in cobalt oxidation state.