Hydrogen Absorption and Electrochemical Properties of As-Quenched Nanocrystalline Mg20Ni10 – xCux (x = 0 – 4) Alloys

Abstract

Nanocrystalline Mg 2 Ni-type alloys with nominal compositions of Mg 20 Ni 10 – x Cu x (x = 0, 1, 2, 3, 4) were synthesized by rapid quenching technique. The microstructures of the as-cast and quenched alloys were characterized by XRD, SEM and HRTEM. The hydrogen absorption and desorption kinetics of the alloys were measured using an automatically controlled Sieverts apparatus. The electrochemical hydrogen storage performances were tested by an automatic gal-vanostatic system. The results show that all the as-quenched alloys hold a typical nanocrystalline structure, and the rapid quenching does not change the major phase Mg 2 Ni. The hydrogen absorption and desorption capacities of the alloys significantly increase with rising quenching rate. Additionally, the rapid quenching significantly improves the electrochemical hydrogen storage capacity of the alloys, but it slightly impairs the cycle stability of the alloys.