Hydrogen absorption/desorption characteristics of Mg-V-Ni hydrogen storage alloys

In this study, Mg+5at%V+5at%Ni alloys are prepared by wet mechanical alloying (MA) in an organic solvent under a purified argon atmosphere. The hydrogen absorption capacities of the samples are evaluated at 473 K at an initial hydrogen pressure of 0.2 MPa in a Sieverts apparatus. First, to obtain the ideal hydrogen absorption and desorption characteristics, organic solvents for milling are changed. Among the alloy samples milled with different organic solvents, the maximum hydrogen absorption capacity is obtained for the alloy prepared with benzene. After determining the organic solvent, the milling time was varied from 3 to 8 h. The maximum hydrogen absorption capacity of 5.15 mass% can be achieved in 7 h-milling. Furthermore, the apparent hydrogen diffusion coefficients are obtained by fitting the temporal change of the hydrogen absorption capacity with a theoretical curve. The theoretical curves are calculated, assuming that the particle shape is a sphere and the size of the sample is 40 μm.