The Influence Of Rare Earth Hydrides On The Hydrogen Storage Properties Of Magnesium Hydride

Mg-based hydrogen storage material is a highly potential material for hydrogenstorage due to its high hydrogen storage capacity, abundant resources and low cost.However, its practical application has been prevented by high thermodynamic stability andpoor kinetics during hydrogen absorption/desorption. In this paper, a series of compositescomposed by MgH2and additives were prepared by mechanical ball milling. The catalyticmechanism and the effect of additives on the hydrogen storage properties of MgH2wereinvestigated in detail.MgH2+20wt.%REHx(RE=Ce、Pr、Nd) composites were prepared by mechanical ballmilling. Basing on the experiment data, it was found that rare earth hydrides couldsignificantly improve hydriding/dehydriding kinetic properties of MgH2. For example,MgH2+20wt.%CeHxcould absorb3.2wt.%H2within300s at473K,2.48wt.%H2morethan pure MgH2at the same condition. The composite could release0.57wt.%H2within600s at573K and pure MgH2could only release almost0.1wt.%H2. In addition, X-raydiffraction result presented that the CeH2.51phase transformed to be CeH2.29phase, whichled to MgH2cell volume contraction and was beneficial to enhance the hydrogendesorption process of MgH2. What’s more, PrHxand NdHxwere significant to improve thehydrogen storage properties of MgH2, and the catalytic mechanism was similar to CeHx.In order to improve the hydrogen storage performances of MgH2furtherer, additiveswith more activity catalytic were developed. MgH2+10wt.%NbH+10wt.%LaH3composite was prepared by mechanical ball milling. Compared with undoped MgH2, theonset dehydrogenation temperature of the composite was94.26K lower and the hydrogendesorption capacity at548K was0.57wt.%higher. What’s more, the co-catalytic effect ofLaH3and NbH was more obvious than their single catalysis to MgH2. It should be due tothat NbH could decrease hydrogen reaction activation energy of MgH2obviously andLaH3could also catalyze to improve the hydrogen storage performance of MgH2. Theconcerted catalysis of NbH and LaH3could enhance the hydrogen storage properties ofMgH2more obviously.