Determination of chemical diffusion coefficients in metal hydride particles with a microelectrode technique

Microelectrochemical studies for hydrogen storage materials have been carried out by using a microelectrode technique. A carbon fiber filament was contacted with single particles of LaNi4.5Al0.5, LmNi(4.0)Cr(0.4)Mn(0.3)Al(0.3), ZrNi1.4, ZrMn0.6Co0.1V0.2Ni1.2, and ZrMn0.4Cr0.4Ni1.2 in 1 M KOH solutions by using a micromanipulator, where Lm indicates the lanthanum-rich rare-earth metal. In this way, cyclic voltammetry and potential step experiments, together with the in situ x-ray diffraction experiments, were conducted and the apparent hydrogen diffusion coefficients in solid phases were determined. The current responses recorded as a function of time were analyzed with a spherical diffusion model and the results are reported herein.