Optimal membrane thickness for proton exchange membrane (PEM) electrolyzer considering gas crossover and membrane degradation

The membrane thickness of proton exchange membrane (PEM) electrolyzers plays a pivotal role in dictating the efficiency, safety and durability of the system. This study establishes a novel multi-physics coupling model integrating electrochemical reaction, gas crossover and membrane degradation to determine optimal membrane thickness in realistic PEM electrolyzers. By considering the different power sources (from power grid or photovoltaic system) and membrane maintenance strategies, the optimal membrane thickness and times of replacement are quantitatively obtained by incorporating particle swarm optimization with techno-economic analysis. The results reveal that thick membranes are preferable for both extremely low input powers and high input powers, due to their high degradation rates and strong hydrogen crossover. For designed membrane lifespan of 80,000 h with constant input power of 2000 W, a critical thickness threshold of 208 μm is identified with one-time scheduled replacement, increasing profitability by 3.5 % compared with the usage of a 337-μm-thick membrane. Regional analysis for photovoltaic-integrated systems demonstrates significant variations of membrane thickness and times of replacement, which corresponds to solar fluctuation patterns. These findings provide valuable insights and theoretical support for enhancing the safety and efficiency of PEM electrolyzers in different application scenarios.