On the anomalous behaviour of deeply discharged, sealed NiCd cells

Abstract

Some sealed NiCd cells on a deep, constant-current discharge show anomalous behaviour in that their voltage remains (after polarity reversal) i the range from −6O to −260 mV. This situation can sometimes persist for an unlimited time without any increase in the overpressure in the cell or of its voltage. A necessary condition for the appearance of this discharge voltage level is a discharge capacity reserve of the cadmium electrode and the presence of cadmium in the separator as a result of its migration from the negative to the positive electrode. The cadmium particles form bridges across the separator leading eventually to a short circuit, whereby the electrode reactions in the cell cease. This concept was substantiated by using separators impregnated with Cd(OH) 2.