Hydrogen Storage Properties of Mg Alloy Prepared by Incorporating Polyvinylidene Fluoride via Reactive Milling

In the present work, we selected a polymer, polyvinylidene fluoride (PVDF), as an additive to improve the hydrogenation and dehydrogenation properties of Mg. 95 wt% Mg + 5 wt% PVDF (designated Mg-5PVDF) samples were prepared via milling in hydrogen atmosphere (reactive milling), and the hydrogenation and dehydrogenation characteristics of the prepared samples were compared with those of Mg milled in hydrogen atmosphere. The dehydrogenation of magnesium hydride formed in the as-prepared Mg-5PVDF during reactive milling began at 681 K. In the fourth cycle (n=4), the initial hydrogenation rate was 0.75 wt% H/min and the quantity of hydrogen absorbed for 60 min, $H_a$ (60 min), was 3.57 wt% H at 573 K and in 12 bar $H_2$. It is believed that after reactive milling the PVDF became amorphous. The milling of Mg with the PVDF in hydrogen atmosphere is believed to have produced defects and cracks. The fabrication of defects is thought to ease nucleation. The fabrication of cracks is thought to expose fresh surfaces, resulting in an increase in the reactivity of the particles with hydrogen and a decrease in the diffusion distances of hydrogen atoms. As far as we know, this investigation is the first in which a polymer PVDF was added to Mg by reactive milling to improve the hydrogenation and dehydrogenation characteristics of Mg.