ELECTRODE PASSIVATION STUDIES.

The possible operation of primary, reserve batteries in a passive mode is discussed. Anodic passivation of reactive metals, such as Zn, Fe, etc., occurs at critical currents which are of the order of 0.1 to 1 ampsq cm. Passive anodes dissolve at current densities less by orders of magnitude than the critical current. An anode can be put into the passive state and maintained in this condition by an appropriate electrical pulse followed by a suitable connection to the positive battery electrode. Activation of the anode prior to use can be achieved by a cathodic electrical pulse which reduces the passive film. The activation time may be from a few milliseconds to seconds, depending on the magnitude of the cathodic pulse. The Fe and Fe-Cr systems have been examined as possible anodes in HClO4 solutions. Data on passivation of these systems suggest that a Fe alloyacid electrolytePbO2 reserve battery could be operated in the passive mode. Author