Hydrogen diffusion in the anode of Ni/MH secondary batteries

Abstract

Hydrogen diffusion coefficients ( D ) were evaluated in a LaNi 4.7 Al 0.3 metal hydride electrode as a function of depth of discharge (DoD) using a newly developed electrochemical method which describes more precisely the practical diffusion behavior. It was found that the hydrogen diffusion coefficient in this electrode increases with increasing DoD at ambient temperature, and for this electrode at 50% DoD, the hydrogen diffusion coefficient increases with increase in temperature, and the activation energy for hydrogen diffusion is 37.3 kJ mol −1 .