Effects of Pd addition on electrochemical properties of MgNi

Two kinds of Pd-modified MgNi were prepared and effects of Pd addition on the electrochemical properties of MgNi were investigated. Sample I was prepared by ball-milling amorphous MgNi with Pd (1, 6 and 10mol%) for 10min, 2 and 10h, and sample II was obtained by ball-milling Mg₂Ni and Ni with 10mol% Pd for 80h. The effects of Pd-modification for sample I depended on both Pd ratio and time of ball-milling. During the ball-milling, Pd became amorphous and distributed rather uniformly not only on the surface but also in the bulk of MgNi powder. At 6 and 10mol% Pd, the degradation of discharge capacity of MgNi was significantly decreased. As for sample II, the cycle life was remarkably improved by the Pd-modification. Analyses of the roles of Pd on the behavior of MgNi showed that the improvements of MgNi properties by both Pd-modifications were not due to the increase in hydrogen absorption ability but caused by the suppression of Mg(OH)₂ formation.