During the past decades, a significant amount of excellent scientific results has been generated in the field of polymer electrolyte membrane water electrolysis (PEMWE). Compared to current state-of-the-art technologies, PEMWE offers the opportunity to produce green hydrogen with zero carbon emissions. However, the membrane electrode assembly (MEA), whose price is still high for a rather limited lifetime, needs further improvement in terms of performance, cost, and durability. In order to efficiently process novel materials, accelerated stress tests (ASTs) can be implemented to provoke and investigate cell ageing processes and assess failure modes under real-life conditions. In this review, the different accelerated stressors of the main components of the MEA are discussed, and recent publications of ASTs in the study of PEMWE cell durability are summarized. Furthermore, a concise review of the degradation mechanisms for the individual MEA components depicted in recent publications is presented. The different aspects identified in this review serve as a roadmap to further advance the durability of novel stack materials.

Polymer electrolyte membrane water electrolysis (PEMWE) is a leading candidate for the development of a sustainable hydrogen infrastructure. The heart of a PEMWE cell is represented by the membrane electrode assembly (MEA), which consists of a polymer electrolyte membrane (PEM) with catalyst layers (CLs), flow fields, and bipolar plates (BPPs). The weakest component of the system is the PEM, as it is prone to chemical and mechanical degradation. Membrane chemical degradation is associated with the formation of hydrogen peroxide due to the crossover of product gases (H₂ and O₂). In this paper, membrane failure due to H₂ crossover was addressed in a membrane-focused accelerated stress test (AST). Asymmetric H₂O and gas supply were applied to a test cell in OCV mode at two temperatures (60 °C and 80 °C). Electrochemical characterization at the beginning and at the end of testing revealed a 1.6-fold higher increase in the high-frequency resistance (HFR) at 80 °C. The hydrogen crossover was measured with a micro-GC, and the fluoride emission rate (FER) was monitored during the ASTs. A direct correlation between the FER and H₂ crossover was identified, and accelerated membrane degradation at higher temperatures was detected.

The assessment of PEM water electrolyzer (PEMWE) degradation is essential for understanding their long-term durability and performance under real-world conditions. This research focuses on the fluoride emission rate (FER) as a crucial parameter during PEMWE operation. Two different FER analysis methods were evaluated, considering their feasibility and ease of integration into a PEMWE system. Various stressors were examined to gain insights into membrane degradation and explore potential mitigation strategies. The utilization of a photometric detection method allowed for the quantification of FER in each test. Results highlight a noteworthy correlation between applied stressors and FER, with variations depending on specific test conditions. An accelerated stress test conducted for 100 hours revealed a high FER at the anode of 0.83 μg h⁻¹ cm⁻² during the initial phase. Correspondingly, energy dispersive X-ray (EDX) mapping showed a reduction in Nafion™ content on the catalyst-coated membrane (CCM) surfaces, likely impacting proton conductivity and performance. Electrochemical results further support these findings, indicating performance changes corresponding to the observed membrane degradation.

PEM water electrolysis (PEMWE) is a promising technology for hydrogen production from renewable energy sources. However, the quality of feed water significantly impacts performance and durability of PEMWE, and cost-intensive purification steps are required to reach a water resistivity of >18.2 MΩ*cm. To omit scarcity of groundwater, one major aim is to use alternative water sources, such as feed water generated by the desalination of seawater. After the desalination process, seawater still contains low amounts of ionic contaminants. In this study, the effect of Cl⁻ contaminants on the performance of a PEMWE single cell was tested with an accelerated stress test. After 50 h of operation, a 23% increase in the cell voltage was observed and Cl⁻ adsorption and catalyst detachment on the electrodes were detected. The fluoride emission rate (FER), as indicator for membrane degradation, was found to be 4-fold higher for the cell exposed to the Cl⁻ contaminant.

A new method for measuring membrane degradation in polymer electrolyte fuel cells (PEFCs) is proposed. The method is based on the detection of fluoride ions in effluent water from the cathode- and anode outlet of the PEFC using photometry (PM). The fluoride emission rate (FER) is an indicator of the membrane’s state of health (SoH) and can be used to measure the chemical membrane degradation. Commercial catalyst-coated membranes (CCMs) have been tested at 80 °C and 90 °C at 30% relative humidity (RH) to investigate the reliability of the developed method for fuel cell effluent samples. To verify the measurement, a mean-difference plot was created by measuring the same data with a fluorine selective electrode. The average difference was at ±0.13 nmol h⁻¹ cm⁻², which indicates good agreement between the two methods. These new findings imply that PM is a promising method for quick and simple assessment of membrane degradation in PEM technology.