Effect of Distances between Electrodes, Agitation and Chemical Pickling Treatment in a Specific Electrolytic Cell for Alkaline Water Electrolysis

Abstract

In order to build an alkaline water electrolyzer in the future, in this work we investigated the following aspects: (1) the effect of the presence of a physical diaphragm; (2) distances between electrodes; (3) the use of the same electrode material, stainless steel 316L, without and with a chemical acid treatment; (4) agitation and (5) the addition of a surfactant to the electrolyte. All these parameters were analyzed in a specific electrolytic cell constructed for that purpose. The objective of this experimental work is to establish the optimal operational conditions proposed for alkaline water electrolysis. The results obtained showed that the presence of a physical diaphragm increases resistance but when the electrodes are near (no more than 5 mm) the current density increases. No evidence of bubble resistance was observed in the nearest distances proposed. The chemical pickling proposed did not show an increase in the active area of the electrodes because it decreased the depth of the roughness which is characteristic of the commercial material and it generated porosities or cavities where the bubbles formed were retained. Agitation improved performance when electrodes with a chemical acid treatment were tested because removal of bubbles formed in their tortuous surface is favored.