Journal of the Electrochemical Society, Vol.147, No.11, 4065-4070, 2000
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 activation and capacity were investigated. In the pulse-potential process, the electrode showed fairly good activation and high discharge capacity when the hydriding and dehydriding potentials were set at -1.2 and -0.8 V, respectively, with respect to an Hg/HgO electrode. Similar results were found in the pulse-current process, for which applicable hydriding and dehydriding currents 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 discharge 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 activation. 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 stability and high-rate discharge capability of pulsed electrodes were superior to those of untreated electrodes.