AC impedance behavior of the Ti4Ni2Oy and Ti3.5Zr0.5Ni2Oy type metal hydride electrodes

The hydrogen storage alloy electrodes of the type Ti4Ni2Oy (y=0, 0.3 and 0.6) and Ti3.5Zr0.5Ni2Oy (y=0.15 and 0.3) were investigated by impedance spectroscopy for potential application as negative electrode in alkaline secondary nickel-metal hydride (MH) batteries. The phase Ti4Ni2O0.30 was found to be electrochemically more stable during the cycling. The addition of copper or nickel powder as current collector improved the electrochemical behavior of the electrodes. It was possible in this way to decrease the charge transfer resistance. These additions have a negligible influence on the stability of electrode material during cycling.