Influence of long-term ageing upon the capacity of hydrogen storage in two novel Mg-Ni-In-C alloys

We have shown previously that the addition of In and C enhances the hydrogen desorption capacity and considerably improves the kinetics of hydrogen desorption from Mg-Ni based alloys, important from the perspective of hydrogen storage.In this paper, we present the results of tests of the long-term stability of the sorption behaviour of these materials.We studied how the capacity and sorption kinetics changed 5 years from the preparation of two chosen Mg-Ni-In-C alloys differing in indium concentration.Kinetic curves and PCT isotherms were measured at temperatures of 250-350 • C. It was found that long-term storage of the hydrogencharged samples led to no significant downgrade in hydrogen sorption kinetics.However, the absorption capacity somewhat decreased from about 5 wt.%H2 to about 3 wt.%H2 due to partial phase decomposition.Relatively intensive tentative oxidation during preparation, which had a slightly beneficial effect on the desorption rate of freshly-prepared samples, caused almost total blocking of hydrogen sorption in the aged samples.K e y w o r d s : hydrogen,