Cathodic Performance of Porous Ag2o/Ag at Low Temperatures

摘要

Polarization during cathodic discharge at constant overall current density was measured for porous electrodes of Ag2O/Ag in 31 weight percent KOH aqueous, at temperatures between 28C (82.5F) and -56C (-68.5F). The electrodes consisted of porous, sintered silver particles bonded to an Exmet support screen, partially charged to Ag2O. At room temperature, the electrodes had less than 35mv polarization at current densities of 200 ma/sq cm (1290 ma/sq in), until almost all of the electrode was discharged. As temperature was decreased, polarization was obtained during the early stages of discharge, the polarization decreased somewhat as discharge continued, and then increased as the electrode approached complete discharge. At about 30 ma/sq cm (194 ma/sq in), initial maximum polarization was about 0.17 volts at-37C (-35F) and was about 0.35 volts at -56C (-68.5F). Results of anodic charging of the electrodes, and anodic discharge of porous zinc electrodes are also reported. Polarization during the initial stages of discharge is about 0.08 volts at 30 ma/sq cm (194 ma/sq in) for the zinc electrodes at -39C (-38F). Future work to determine the causes of polarization of the Ag2O/KOH electrode is discussed.