Yoshiteru Kawabe

Electrochemical Hydrogen Storage in Ti1.6V0.4Ni1−xCox Icosahedral Quasicrystalline Alloys

The discovery of the icosahedral phase (i-phase) in rapidly quenched Ti(1.6)V(0.4)Ni(1-x)Co(x) (x=0.02-0.1) alloys is described herein. The i-phase occurs in a similar amount relative to the coexisting beta-Ti phase. The electron diffraction patterns show the distinct spot anisotropy, indicating that the i-phase is metastable. The electrochemical hydrogen storage performances of these five alloy electrodes are also reported herein. The hydrogen desorption of nonelectrochemical recombination in the cyclic voltammetric (CV) response exhibits the demand for electrocatalytic activity improvement. A discharge capacity of 261.5 mA h g(-1) was measured in a Ti(1.6)V(0.4)Ni(0.96)Co(0.04) alloy electrode at 30 mA g(-1) and 303 K and it is shown that an appropriate amount of Co element addition would enhance the cycling stability at the expense of high-rate discharging ability.

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

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 80-160°C has been done successfully on the basis of two phase models (L and S phase) with large and small c 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 100°C, 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 100°C. The increase in the electrical conductivity for the cobalt oxyhydroxide could be explained by the increase in cobalt oxidation state.

Electrochemical Hydrogen Storage in Ti1.6V0.4Ni1âxCoxIcosahedral Quasicrystalline Alloys

The discovery of the icosahedral phase (i-phase) in rapidly quenched Ti(1.6)V(0.4)Ni(1-x)Co(x) (x=0.02-0.1) alloys is described herein. The i-phase occurs in a similar amount relative to the coexisting beta-Ti phase. The electron diffraction patterns show the distinct spot anisotropy, indicating that the i-phase is metastable. The electrochemical hydrogen storage performances of these five alloy electrodes are also reported herein. The hydrogen desorption of nonelectrochemical recombination in the cyclic voltammetric (CV) response exhibits the demand for electrocatalytic activity improvement. A discharge capacity of 261.5 mA h g(-1) was measured in a Ti(1.6)V(0.4)Ni(0.96)Co(0.04) alloy electrode at 30 mA g(-1) and 303 K and it is shown that an appropriate amount of Co element addition would enhance the cycling stability at the expense of high-rate discharging ability.

Electrochemical hydrogen storage in Ti(1.6)V(0.4)Ni(1-x)Co(x) icosahedral quasicrystalline alloys.

The discovery of the icosahedral phase (i-phase) in rapidly quenched Ti(1.6)V(0.4)Ni(1-x)Co(x) (x=0.02-0.1) alloys is described herein. The i-phase occurs in a similar amount relative to the coexisting beta-Ti phase. The electron diffraction patterns show the distinct spot anisotropy, indicating that the i-phase is metastable. The electrochemical hydrogen storage performances of these five alloy electrodes are also reported herein. The hydrogen desorption of nonelectrochemical recombination in the cyclic voltammetric (CV) response exhibits the demand for electrocatalytic activity improvement. A discharge capacity of 261.5 mA h g(-1) was measured in a Ti(1.6)V(0.4)Ni(0.96)Co(0.04) alloy electrode at 30 mA g(-1) and 303 K and it is shown that an appropriate amount of Co element addition would enhance the cycling stability at the expense of high-rate discharging ability.