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

The discharge capacity, the high-rate dischargeability and the self-dischar ge characteristics of negative electrodes consisting of the Zr-based, modif ied AB, type alloys of ZrV(0.1)Mno(0.7)Ni(1.2) alloy and ZrV0.1Mn0.5Mo0.2Ni 1.2, alloy, the latter having the form of partially substituted Mo for Mn s ites in the former alloy, are investigated in 6 M KOH solution at 30, 40 an d 60 degrees C. II is found that the discharge capacities obtained at 30 an d 40 degrees C are almost the same in both alloys, but they decrease at 60 degrees C. The activation process becomes faster in both alloys with increa sing temperature. The high-rate dischargeability increases slightly from 85 % at 30 degrees C to 90% at 60 degrees C. At the very high discharge curren t of 5 A g(-1), however, the discharge capacity at 60 degrees C was increas ed by 7 X and 17 X more than that at 30 degrees C in ZrV0.1Mn0.7Ni1.2, allo y and ZrV0.1Mn0.5Mo0.2Ni1.2, alloy, respectively. The addition of Mo improv ed the self-discharge characteristics. especially at 60 degrees C. (C) 1999 Elsevier Science S.A. All rights reserved.