Experimental critical analysis of plate impedance

Taking into account that there are no experimental proofs that Electrochemical Impedance Spectroscopy (EIS) four electrode plate cell measurements can be attributed only to the central plate, in the present work measurements with variable counter-electrode plate areas and one and the same central plate were made. This was done in a frequency range from 10 4 to 10 ―2 Hz and at different central plate states of charge. The results show that for positive-negative-positive plate ensembles, at all studied frequencies and state of discharge, the EIS data can be attributed to the central negative plate, except for the highest counter-electrode/central working electrode areas ratio, r, and higher discharge levels, at the lower studied frequencies. Instead of that, for negative-positive-negative ensembles, the EIS data can be attributed to the central positive plate only at the high and middle studied frequencies in all discharge levels and area ratios. Totally charged central positive plates must be excluded because their impedance depends on the counter-electrode area at all r ratios. All these results are discussed and suppositions are made for their interpretation.