INCREASE OF SPECIFIC SURFACE-AREA OF METAL-HYDRIDES BY LIXIVIATION

In this paper, we present a new and powerful method to increase the sp ecific surface area of nanocrystalline ball milled materials. The meth od consists of using a lixiviation technique to increase the surface a rea. The element to be lixiviated is ball milled with the hydrogen-abs orbing alloy. After complete mixing, the lixiviated element is leached in an appropriate solution. The end product is a porous metal hydride with high specific surface area. The system magnesium-lithium is pres ented as an example. The results show that before lixiviation, the all oys absorb hydrogen slowly and the hydrogen capacity is reduced due to the presence of lithium. After lixiviation, the specific surface area shows a ten-fold increase and the hydrogen sorption kinetics are fast er. (C) 1998 Elsevier Science S.A.