Hydrogen diffusion and effect of grain size on hydrogenation kinetics in magnesium hydrides

Hydrogenation and dehydrogenation of metal hydrides are of great interest because of their potential in on-board applications for hydrogen vehicles. This paper aims to study hydrogen diffusion in metal hydrides, which is generally considered to be a controlling factor of hydrogenation/dehydrogenation. The present work first calculated temperature-dependent hydrogen diffusion coefficients by a theoretical model incorporated with experimental data in a Mg-based system and accordingly the activation energy. The grain size effect on diffusion in nanoscale was also investigated.