Abstract
A series of Laves phase AB 2 metal hydride electrodes based on Zr(Mn,Ni) 2 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 better electrochemical performance. During the cyclic charge-discharge test, manganese was decomposed from the electrode, causing degradation of the electrode. Overcharge caused faster degradation of the electrode. Based on the compositions studied, the composition ZrMn 0.6 V 0.2 Co 0.1 Ni 1.2 is recommended as a good electrode material. Its discharge capacity at a discharge rate 50 mA/g was approximately 350 mAh/g. It also maintained excellent discharge capacities when discharged at higher rates.