Effect of temperature on the discharge capacity of the Laves phase alloy used in nickel/metal-hydride batteries

摘要

The discharge capacity, the high-rate dischargeability and the self discharge characteristics of negative electrodes consisting of the Zr-based, modified AB_2 type alloys of ZrV_0.1Mn_0.7Ni_l.2 alloy and ZrV_0.1Mn_0.5Mo_0.2Ni_l.2 alloy, the latter having the form of partially substituted Mo for Mn sites in the former alloy, are investigated in 6 M KOH solution at 30, 40 and 60deg. C. lt is found that the discharge capacities obtained at 30 and 40deg. C are almost the same in both alloys, but they decrease at 60deg. C. The activation process becomes faster in both alloys with increasing temperature. The high-rate dischargeability increases slightly from 85/100 at 30deg. C to 90/100 at 60deg. C. At the very high discharge current of 5 A g~-1, however, the discharge capacity at 60deg. C was increased by 7 X and l7 X more than that at 30deg. C in ZrV_0.1Mn_0.7Ni_1.2 alloy and ZrV_0.1Mn_0.5Mo_0.2Ni_l.2 alloy, respectively. The addition of Mo improved the self discharge characteristics, especially at 60deg. C.