Effects of the operation mode on the degradation behavior of anion exchange membrane water electrolyzers

In the present study, the effects of the operation mode on the stability of anion exchange membrane water electrolyzers (AEMWEs) are investigated. AEMWEs are tested for ~1000 h under two different potentiostatic (1.95 V) conditions (short periodic and long periodic modes), and their degradation behavior are compared. Changes in ohmic and non-ohmic resistance are distinguished and traced out by regularly measuring the impedance spectra during the long-term test. The short periodic operation mode results in performance degradation due to the ohmic resistance, which is associated with the irreversible membrane degradation, while non-ohmic resistance follows increase and decrease patterns, which is associated with the nonpermanent bubble resistance. On the other hand, the long periodic operation mode results in a better stability with the ohmic and non-ohmic resistance value remaining almost constant during the test. The present study indicates that even a small operating factor such as the frequency of the rest time has a significant impact on the stability of cell. Thus, various possible operation modes with respect to the rest time should be taken into account for preventing an increase in the degradation rate of AEMWEs.