Durability of PEM water electrolyzer against wind power voltage fluctuation

The durability of a water electrolysis cell against wind power voltage fluctuations was evaluated by developing an accelerated potential fluctuation test protocol based on wind power voltage fluctuations over an actual 24 h period of operation. Accelerating potential protocol tests corresponding to 160 d of actual operation were performed. The current loss during the test is mostly recovered if rest time was included during the operation. Reversible loss is most likely related to gas stagnation, suppression of oxygen reduction reaction activity owing to the formation less active Ir(V) species, and suppression of gas evolution owing to the increased hydrophilic surface. This irreversible loss can be attributed to the dissolution of IrO2 and the loss of Nafion® ionomer. Even though the potential fluctuation itself was not a problem if the lowest potential was 1.0 V, the upper limit of the potential was rather problematic. When the upper potential is increased to 2.3 V, the oxidation of IrO2 is enhanced, leading to the partial dissolution of IrO2, followed by the formation of a dense structure, a decrease in the oxygen evolution reaction activity, and an increase in the surface hydrophilicity.