A series of Laves phase AB(2) metal hydride electrodes based on Zr(Mn,Ni),
were studied. Partial substitution or addition with Ti,V, and Co was made,
and most of the alloys maintained the C15-type structure. The alloy powders
were coated with Ni by electroless plating for electrode application. The
charge-discharge properties were examined and correlated with the gas-phase
hydrogenation properties. Alloys with a large hydrogen desorption capacity
, a small hysteresis, and a flat plateau pressure at around 0.1 MPa had bet
ter electrochemical performance. During the cyclic charge-discharge test, m
anganese was decomposed from the electrode, causing degradation of the elec
trode. Overcharge caused faster degradation of the electrode. Based on the
compositions studied, the composition ZrMn0.6V0.2Co0.1Ni1.2 is recommended
as a good electrode material. Its discharge capacity at a discharge rate 50
mA/g was similar to 350 mAh/g. It also maintained excellent discharge capa
cities when discharged at higher rates. (C) 2000 Elsevier Science B.V. All
rights reserved.