Numerical Simulation of Gradient Pore Structures in Anodes for Anion Exchange Membrane Water Electrolysis

To mitigate the gas–liquid mass-transfer bottleneck in anion-exchange membrane water electrolysis (AEMWE), a 3D multiphysics numerical model was developed to systematically investigate the regulatory effects of gradient porosity (GPD) and gradient pore-size distribution (GPSD) on anode reaction kinetics and cell polarization. Single-factor analysis reveals that increasing the GPD/GPSD from the membrane side toward the flow channel side effectively reduces activation overpotential due to the high specific surface area of small pores near the membrane, while simultaneously lowering mass-transfer resistance through high porosity and large pores near the flow channel. Conversely, a decreasing gradient leads to localized gas stagnation and uneven mass transfer, deteriorating cell performance. Furthermore, an innovative synergistic design is proposed featuring a simultaneous linear increase in porosity (0.6 to 0.9) and pore diameter (0.11 to 0.17 mm). This configuration achieves a cell voltage of only 1.812 V at 1100 mA/cm2 (1 mol/L KOH, 80 °C), approximately 40 mV lower than that of conventional uniform structures, thereby significantly reducing energy consumption at high current densities. This study provides a mechanistic framework for the precise architectural design of high-performance AEMWE electrodes, highlighting the importance of spatial heterogeneity in optimizing two-phase transport.