Mechanically Alloyed Nanocrystalline Hydrogen Storage Materials

Abstract

Mechanical alloying and mechanical grinding have been used to synthesize or treat AB, AB₂, and AB₅ type alloys and Mg-based hydrogen storage materials. A nanocrystalline or an amorphous structure was obtained after milling, depending on the system and its composition. The structure and the hydrogen storage properties of various nanocrystalline alloys were investigated. It was found that the activation and kinetics of hydrogen absorption/desorption were improved. However, a severe loss of storage capacity was observed in the AB, AB₂ and AB₅ systems, but not much in Mg-based systems. The storage capacity can be recovered by thermal annealing at elevated temperatures. A preliminary explanation is given for the change of absorption/desorption kinetics and storage capacity.