Electrochemical study of hydrogen diffusion behavior in Mg₂Ni-TYPE hydrogen storage alloy electrodes

By Cui, N. & Luo, J.L.
Published in International Journal of Hydrogen Energy NULL 1999

Abstract

Hydrogen diffusion behavior in Mg₂Ni-type hydrogen storage alloy electrodes was characterized by using both potentiostatic polarization method, based on a spherical diffusion model, and electrochemical impedance spectroscopy (EIS) technique. The values of the diffusion coefficients of hydrogen in Mg₂Ni and Mg₁.₉V₀.₁Ni₀.₈Al₀.₂ are 1.2 X 10-¹¹ ∼ 1.57 X 10-¹⁰ and 3.1 ∼ 7.6 X 10⁻⁹ cm²/s, respectively. The values of diffusion coefficients decline notably with the increase in depth of discharge (DOD). The decay rate of diffusion coefficient in Mg₂Ni with DOD is much quicker than that in Mg₁.₉V₀.₁Ni₀.₈Al₀.₂. The experimental results suggested that the substitutions of V and Al for Mg and Ni in Mg₂Ni could significantly improve the hydrogen diffusion performance in this alloy and thus substantially increase discharge capacity of the electrode. © 1998 International Association for Hydrogen Energy

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