Effect of morphology on the performance of metal-hydride electrodes

Electrochemical studies on AB(2) type Zr0.5Ti0.5V0.6Cr0.2Ni1.2 metal hydrid e electrodes with varying particle size suggests that the electrodes with a lloy particles of about 60 mu m yield the optimum performance. The values f or diffusion coefficient of hydrogen in the alloy particles > 25 mu m are f ound to be nearly invariant. Both a.c. impedance and linear polarization da ta on electrodes with varying particle size suggest that the charge-transfe r resistance depends on state-of-charge of the electrodes. A comparison of scanning electron micrographs of fresh electrodes and subsequent to their p rolonged charge-discharge cycling suggests that the metal hydride particles develop stress-induced cracks owing to their inherent expansion and contra ction during the hydriding/dehydriding processes.