HYDROGEN-STORAGE ALLOY, HYDROGEN-STORAGE ALLOY ELECTRODE, SECONDARY CELL, AND PROCESS FOR PRODUCING HYDROGEN-STORAGE ALLOY

摘要

A hydrogen-storage alloy characterized by containing a phase comprising a Pr5Co19-form crystal structure having a composition represented by the general formula A(4-w)B(1+w)C19 (wherein A represents one or more elements selected among the rare earth elements including Y (yttrium); B represents Mg; C represents one or more elements selected from the group consisting of Ni, Co, Mn, and Al; and w indicates a number in the range of -0.1 to 0.8) and by having an overall composition represented by the general formula R1xR2yR3z (wherein 15.8≤x≤17.8, 3.4≤y≤5.0, and 78.8≤z≤79.6, provided that x+y+z=100; R1 is one or more elements selected among the rare earth elements including Y (ytterium); R2 is Mg; R3 is one or more elements selected from the group consisting of Ni,Co, Mn, and Al; and that part of the z which indicates Mn+Al is a value of 0.5 or larger and that part of the z which indicates Al is a value of 4.1 or smaller).