Hydrogen storage properties of LaNi3.8Al1.0M0.2 (M = Ni, Cu, Fe, Al, Cr, Mn) alloys

The crystal structure, activation performance. hydrogen storage properties. thermodynamics, pulverization resistance and absorption/desorption kinetics of LaNi13.8Al10M0.2 (M = Ni, Cu, Fe, Al, Cr, Mn) hydrogen storage alloys were investigated systemically The absorption/desorption pressure-composition (PC) isotherms and kinetics were measured at a temperature range of 413-493 K by the volumetric method It was found that all the investigated alloys showed CaCu5 type of hexagonal structures and the partial substitution of M for Ni resulted in the increase of the unitcell volumes in an orderof Ni < Cu < Fe < Al < Cr < Mn The activation became easier with Cr substitution for partial Ni but a little harder for the Cu, Fe, Mn, Al contained alloys M elements decreased the absorption/desorption plateau pressure in an order of LaNi4Al > LaNi3.8Al10Cu0.2 > LaNi3.8Al10Fe0.2 > LaNi3.8Al10CrO2 > LaNi3.8Al10Mn0.2 > . There were linear relationships between plateau pressure and cell volume of tile investigated alloys The absolute values of the enthalpy for all the alloys were increased with M substituteJ for partial Ni. Al and Cu improved the pulverization resistance. The absorption kinetics was very fast while the necessary times taken by LaNi3.8Al1.0M0.2 alloys to desorb 90% of their maximum hydrogen capacity were increased in an order of Ni < Cu < Fe < Al < Cr < Mn. (C) 2009 Elsevier B V All rights reserved