Pulse activation of hydrogen-storage alloy electrodes in nickel/metal hydride batteries

Both pulse-potential and pulse-current processes were employed to activate hydrogen-storage alloy electrodes. Parameters that affect the electrode act ivation and capacity were investigated. In the pulse-potential process, the electrode showed fairly good activation and high discharge capacity when t he hydriding and dehydriding potentials were set at -1.2 and -0.8 V, respec tively, with respect to an Hg/HgO electrode. Similar results were found in the pulse-current process, for which applicable hydriding and dehydriding c urrents were 400 and 200 mA g(-1), respectively. An increase in total pulse time was not only useful for activation but also beneficial to the dischar ge capacity. The time interval had little effect on the electrode capacity but significantly influenced the activation process. A longer ratio of t(on )/(t(on) + t(off)) enhanced the electrode maximum capacity but retarded act ivation. An appropriate ratio of t(on)/(t(on) + t(off)) for pulse-potential was 0.5, and for pulse-current it was 0.83. In addition, the cycle-life st ability and high-rate discharge capability of pulsed electrodes were superi or to those of untreated electrodes. (C) 2000 The Electrochemical Society. S0013-4651(00)05-026-6. All rights reserved.