Durability assessment of single-cell AEMWE configurations under accelerated stress testing

This work studies the durability of Anion Exchange Membrane Water Electrolysers by applying an Accelerated Stress Test (AST) protocol to two different membrane configurations: the standard Fumasep® FM-FAA-3-50 and the reinforced Fumasep® FM-FAA-PK-3-75, which incorporates a polyether ketone (PK) matrix for increased mechanical stability. Although AEMWEs are emerging as a promising and cost-effective technology for hydrogen production, their limited durability remains a major barrier to large-scale deployment, with degradation processes not fully understood. Therefore, a comprehensive characterisation of the cell and its components was performed, combining mechanical and chemical analyses (SEM-EDS), electrolyte ion chromatography and electrochemical methods (VI curves, EIS spectra). Durability tests, consisting of 192 h AST protocol, revealed, after an initial break-in phase, a gradual increase in cell voltage during prolonged operation (0.58–0.63 mV/h at nominal current) attributed to structural and functional degradation of both the membranes and electrodes. The main degradation mechanisms identified include the loss of cationic functional groups due to OH − attack, catalyst dissolution and agglomeration, along with progressive deterioration of the membrane-electrode assembly. The intermittent operation introduced by the AST protocol further aggravated the decline in performance, with periods of shutdown leading to membrane dehydration and gas stagnation, resulting in increased ohmic resistance and hindered interfacial kinetics (up to +19 % and +18 % in ohmic and polarization resistances, respectively). Periodic replacement of the electrolyte allowed partial recovery of cell performance, mitigating reversible losses (up to −18 % in ohmic resistance). To ensure the long-term viability of AEMWE, the improvement of both the chemical and mechanical stability of membranes is necessary, thereby enabling sustainable and efficient hydrogen production under real operating conditions.