Polarization Impedance at Low Frequencies

Publisher Website
Google Scholar
Abstract
The polarization capacity of a Pt–H2SO4–Pt electrolytic cell of concentration 0.25 N has been studied using alternating currents ranging in frequency from 0.05 to 3500 cycles per second and using aperiodic currents whose time constants range from 0.15 to 1.5 seconds. The empirical law, C=13.6f−m , is found to hold throughout the frequency range with m=0.11. The angle Ψ by which the current fails of quadrature with the polarization is constant within the accuracy of measurement and is in agreement with the Fricke relation, Ψ=πm/2. The capacity as measured by aperiodic currents is found to increase slightly with the time constant. It is shown by a Fourier series expansion that if the alternating current results are correct, the aperiodic decay current is approximately exponential during the early part of the decay and that the measuredpolarization capacity is approximately proportional to the mth power of the time constant. The experimental data are in agreement with this conclusion.