Transient and Failure Analyses of the Porous Zinc Electrode: II . Experimental

Cf. preceding abstract. Experiments were conducted to characterize behavior and failure mechanisms of porous Zn electrodes prepared by pressing amalgamated Zn powder of particle size ranging from 250-325 mesh. The Zn test electrodes were disks with a cross-sectional area of 1 cm2 and a thickness of 0.1 cm. Distribution of Zn and ZnO, and electrode overpotentials were measured during galvanostatic discharge in 40 wt.-% KOH solution saturated with ZnO. The observed reaction profiles were highly nonuniform and the reaction zone, located near the electrode surface, was very thin, typically 0.2 mm. The utilization of the present electrodes was very sensitive to the applied current density, initial porosity, amount of electrolyte and the type of membrane. The measured reaction profiles and overpotentials were compared with the theoretical predictions of a recently developed mathematical model. The agreement between observations and predictions provides a good interpretation of the discharge failure modes of negative Zn electrodes.39 refs.--AA