Impact of applied potential range on corrosion behavior of stainless steel oxygen evolution electrode under potential cycle loading

We investigated the corrosion behavior of 310S stainless steel anode for alkaline water electrolyzer under various triangle-wave potential cycle loadings by changing the lower (x) and higher (y) vertex potentials to simulate the power fluctuation characteristics of renewable energy sources. The anode was subjected to the loadings of x = 0.5-1.5 and y = 1.8-2.5 V in 7 M KOH solution. The dissolution of Fe and Cr into the electrolyte depended significantly on x. Notably, under conditions of x >= 1.35 V, the total dissolution amounts of Fe and Cr after the 20,000 potential cycles decreased to approximately 7 % of the condition where x = 0.5 V. Conversely, y had less influence on the total dissolution amounts. Interestingly, the molar ratios of the eluted Fe and Cr into the electrolyte depended on both x and y, suggesting distinct corrosion behaviors of the stainless steel induced by the potential cycles of x <= 1.35 and y = 1.8 V, compared to those at x >= 1.35 and y = 2.5 V. These findings suggest the importance of precise potential control of the stainless steel anode in alkaline water electrolysis for preventing potential fluctuation-induced corrosion.