Experimental study of the influences substitution from Ni by Co, Al and Mn on the hydrogen storage properties of LaNi3.6Mn0.3Al0.4Co0.7 alloy

The hydrogen storage properties of LaNi3.6Mn0.3Al0.4Co0.7 alloy were improved by the addition of Co, Mn and Al. The phase compositions and crystal structures of this alloy were characterized via X-ray diffraction and Scanning Electron Microscopy. The gravimetric study showed that the average size of the particles was about 10 mu m. The isotherms of reactions and the hydrogen absorption capacity were measured in the temperature range of 20-40 degrees C. Hence, the enthalpy (Delta H) and entropy (Delta S) were also calculated. The obtained experimental results showed that this compound can absorb and desorb hydrogen in a reversible way in normal operating conditions (temperature T = 20 degrees C and pressure P = 6 bar). The hydrogen sorption measurements revealed the effect of the partial substitution of Ni by Al, Mn and Co on the crystal structure of our compound. This substitution led to a significant reduction of hysteresis between hydriding and dehydriding. Thus, the substitution of Ni by these elements led to a larger size of interstitial voids and, therefore, the possibility of a higher number of hydrogen atoms in the cell. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.