Transport modelling of the anion exchange membrane electrolyser: mechanistic insights and performance analysis

Anion exchange membrane (AEM) water electrolysis offers promise for cost-effective green hydrogen, where performance is governed by coupled electrochemical and transport processes within the membrane-electrode-assembly (MEA). A first-principles multiphysics model is developed, resolving individual MEA layers to quantify activation, ohmic, and transport losses. The model shows good agreement with experimental polarization data over 40–70 °C. Increasing temperature improves hydroxide-ion conductivity and reaction kinetics, current density rising 34% at 1.9V. Parametric analysis indicates that higher exchange current densities reduce activation losses, with greater sensitivity at anode. Ionic potential analysis reveals membrane thickness >50 μm significantly increases ohmic losses. The optimal catalyst layer thickness is ∼10–50 μm, balancing the kinetics and transport resistance. Electrolyte concentration improves performance up to ∼0.3 M, beyond which gains are marginal. The effects of carbonation show a non-negligible impact (∼1%). Overall efficiency decreases from ∼96.9% at 1.5V to ∼46.8% at 1.9V, highlighting the trade-off between hydrogen production rate and energy efficiency.