Hydrogen absorption/desorption property of (La,Ce,Pr)(Ni,Mn,Al)₅ alloys

Compositions of low-cost (La,Ce,Pr)(Ni,Mn,Al)₅ alloys having hydrogen storage properties comparable to those of (La,Ce,Nd,Pr)(Ni,Co,Mn,Al)₅ commercial alloy were suggested. The compositions were obtained by simultaneously increasing the proportions of Ce, Ni, and Mn and reducing the proportions of Nd and Co. The compositions of the low-cost alloy were proven to be useful through estimation of the hydrogen storage capacity, plateau pressure, and cycling property. It was found that the hydrogen storage capacity and plateau pressure of the low-cost (La,Ce,Pr)(Ni,Mn,Al)₅ alloys are similar to those of the (La,Ce,Nd,Pr)(Ni,Co,Mn,Al)₅ commercial alloy. The hydrogen storage capacity of the low-cost alloy was observed to degrade slightly (about 9%) after 1000 iterations of cycling due to the protective effect of mischmetal and Al, even though the low-cost alloy does not contain Nd and Al in proportions different from those of the commercial alloy.