Investigation of the Effects of Membrane Rupture Aperture and Position on Hydrogen–Oxygen Crossover in Alkaline Water Electrolysis

ABSTRACT With the global transition toward low‐carbon energy, hydrogen is becoming a pivotal element of the clean‐energy landscape. Among hydrogen‐production routes, alkaline water electrolysis (AWE) remains the most mature and cost‐effective technology for large‐scale green hydrogen generation. However, membrane rupture during long‐term operation can trigger hydrogen–oxygen crossover, undermining both system efficiency and operational safety. In this work, we experimentally quantify how rupture aperture and location influence H 2 –O 2 crossover in an AWE cell and use multiphysics simulations as an auxiliary analysis of the electric field and two‐phase flow distribution. For the present electrolyzer (290 cm 2 membrane area), the hydrogen concentration in the oxygen stream increased to 1.212% at a 5 mm aperture, exceeding the adopted early‐warning level of 25% of the lower explosive limit (LEL) but remaining below the LEL of 4%. An above‐LEL concentration was observed only at 7 mm, where the hydrogen concentration reached 5.412%. Rupture location was also important: defects near the membrane edge or in the upper region produced higher measured crossover concentrations. The COMSOL model directly calculates electric‐field and two‐phase‐flow quantities; it does not calculate gas transport through the rupture or the outlet crossover concentration. The simulated distributions are therefore used only for qualitative comparison with the experimental spatial trends. The reported dimensional thresholds are specific to the tested cell and operating conditions.