Comprehensive Performance Assessment of the PEMEC with the Three-Segment Stepwise Porosity Synergy Contact Angle for the Anode Porous Transport Layer by Multiobjective Optimization

Proton exchange membrane electrolyzer cells (PEMECs) feature a rapid dynamic response and broad operating power range, enabling effective mitigation of renewable energy power fluctuations. Oxygen accumulation in the anode porous transport layer (APTL) leads to severe highly nonuniform distributions. This study proposes three-segment stepwise APTL porosity synergy contact angle designs to enhance mass transfer uniformity along the X, Y, and Z directions. A multiphysics PEMEC model is developed to evaluate the effects of stepwise porosity configurations (X–P1–P5, Y–P1–P5, Z–P1–P5) and stepwise contact angle configurations (X–T1–T5, Y–T1–T5, Z–T1–T5) on electrochemical performance. Using maximum current density and minimum relative standard deviation (RSD) as objectives, the COBYLA algorithm is applied to identify optimal porosity synergistic contact angle designs (Case 1–Case 9) achieving simultaneous two-direction optimization. Compared with the uniform APTL (Case 0), the optimal porosity designs X–P5 and Z–P1 and optimal contact-angle designs X–T1 and Z–T5 increase current density by 0.33%, 0.67%, 0.22%, and 0.33%, while improving its uniformity by 0.89%, 3.89%, 3.94%, and 0.75%, respectively. Among all optimization cases, Case 2 featuring Z-direction stepwise porosities of 0.3, 0.5, 0.7 and stepwise contact angles of 75°, 45°, 15° achieves the best mass-transfer enhancement. It yields a 5060 Pa increase in capillary pressure, 1.53% higher current density, 2.43% better uniformity, a 3.78% rise in water saturation and 51.74% improvement in its uniformity, and a 6.83% reduction in concentration overpotential at 2.0 V. The proposed design provides a manufacturable and effective strategy for improving hydrogen production performance in PEMECs.