Phase Structure And Electrochemical Performances Of The As-cast And Quenched (Mg_2.4Ni)_100-xRe_x（Re=la, Ce; X=0-20） Hydrogen Storage Alloys

The paper reviews the research and development of the Mg₂Ni-type alloys both from home andabroad, the Mg_2.4Ni-type hydrogen storage alloys were selected as the object of studying. The cast(Mg_2.4Ni)_100-xRE_x（RE=La,Ce; x=0,5,10,15,20） alloys were prepared by vacuum induction furnace inhelium atmosphere at a pressure of0.04MPa. The use of helium aimed to prevent the volatilizationof Mg during the melting. A part of as-cast (Mg_2.4Ni)_100-xRE_x（RE=La,Ce; x=0,5,10,15,20） wasremelted and spun through melt-spinning with rotating copper roller cooled by water. Themicrostructure and morphology of cast and spun alloys were analyzed by X-ray diffraction （XRD）and scanning electron microscopy （SEM）. The electrochemical and kinetic properties of as-cast andas-spinning (Mg_2.4Ni)_100-xRE_x（RE=La,Ce; x=0,5,10,15,20） alloys were measured by electrochemicalintegrative test system and electrochemical kinetic working station, respectively.The addition of rare earth element La eahanced the formation capability of the amorphous inthe spun (Mg_2.4Ni)_100-xLa_x（x=0,5,10,15,20） alloys. As increasing La content, the main phase of cast(Mg_2.4Ni)_100-xLa_x（x=0,5,10,15,20） alloys change Mg₂Ni phase into LaNi₃₊LaMg₃phase. All castand spun alloys showed good activation performance, addition of La improved electrochemicaldischarge capacity to some degree. Another, the alloys treated by melt spinning technology worsenhydrogen absorption properties. The addition a bit of rear earth element La into the alloys isbeneficial on the electrochemical cycle stability, which is consistent with the alloy electrode opencircuit potential. The high rate discharge properties of the alloy,Whether as-cast alloy or fastquenching state alloy,are decreased with La increased,which is consistent with a trend alloyelectrode dynamic performance.For the (Mg_2.4Ni)_100-xCe_x（x=0,5,10,15,20） alloys, the addition of Ce the changesd phasestructure of alloys. The major phase of as-cast alloys changed Mg₂Ni phase into CeMg₃₊Ce₇Ni₃phase. The maximum capacity of cast alloys increases with rising Ce content, the maximumdischarge capacity and the amount of hydrogen absorption decrease for quenching alloys; the mainreason is the Ce content and quenching techniques lead the phase composition and phase structure tochange. The addition earth element Ce into the alloys is unfavorable on the electrochemical cyclestability, which is consistent with the alloy electrode open circuit potential. The high rate dischargeproperties of the alloy,Whether as-cast alloy or fast quenching state alloy,are improved with Ceincreased,which is consistent with a trend alloy electrode dynamic performance.