Hydrogen Gas-Rechargeable Metal Hydride Electrodes for Ni-MH Battery

摘要

Since metal hydrides can be hydrogenated and dehydrogenated either in gas phase or inelectrolyte, it is possible to fabricate a hydrogen gas-rechargeable electrode for Ni-MHbattery. In this work, a Ni-MH battery was assembled to evaluate the performance for sucha purpose. Some nonbreakable pellets made of an AB5 alloy and Ni powder, were used in abattery such that the anode could be charged in hydrogen gas and discharged in electrolyte.The performance is influenced by hydrogen pressure, discharge current, balance of electrolyte,and contamination in the system. Continuous discharge can be performed on the pelletNi/AB5=25 at a current density of 20 mA/g AB5 and a constant hydrogen pressure 20 atm,even after repeated replacement of new Ni electrodes. It is observed, however, that thepellet acts more like a catalyst for hydrogen dissociation than as an absorbent. In otherwords, the discharge rate of hydrogen atoms on the surface is faster than the penetration rateof hydrogen from the surface to the bulk.