Study On The Preparation And Properties Of AB₃-Type La-Mg-based Hydrogen Storage Alloys

AB₃-Type La-Mg-based hydrogen storage alloys are promisingcandidates for reversible hydrogen storage because of their highdischarge capacities, easy activation and good hydrogen pressure. In thispaper, A series of La-MgTi(Ca)-Ni-Co alloys are prepared in highfrequency induction furnace under Ar atmosphere. The influences ofreplacing element in La-Mg based hydrogen storage alloys on theelectrochemical properties and the hydrogen storage properties werestudied.1. La_0.7Mg_0.3-xTixNi_2.8Co_0.3(X=0.03, 0.06, 0.09, 0.12) hydrogen storagealloys were prepared and the effects of partial substitution Ti for Mg oncrystal structure were studied. The plateau pressure is longer than that ofno Ti substituting and the hysteresis between the hydrogen absorption anddesorption decrease with the amount of substitution Ti for Mgincreasing. The substitution Ti for Mg can improve thermal stability forLa_0.7Mg_0.3-xTixNi_2.8Co_0.3(X=0.03, 0.06, 0.09, 0.12) alloy hydrides, slowdown the capacity degradation and prolong cycle life.2. La_0.7Ca_xMg_0.3-xNi₃Co_0.3(x=0.02-0.10)hydrogen storage alloys wereprepared and the effects of partial substitution Ca for Mg on the structure, electrochemical properties of the alloys were investigated.LaNi₅, CaNi₃, La₂Ni₇ phase exist in these alloys and a newphase, CaMg₂Ni₉, appears with Ca content increasing. Appropriate Ca forMg can improve the hydrogen storage capacity and prolong the cycle life.Moreover, the absorption plateau became shorter, the hysteresis betweenthe hydrogen absorption and desorption increase with the amount of thesubstitution Ca for Mg increasing and the reversibility of all alloys isworse than that of no Ca substituting.