Plasma‐Engineered Polyethylene‐Reinforced Anion Exchange Membranes With Low Ionic Resistance and Low Hydrogen Crossover for Water Electrolysis

Abstract

ABSTRACT Anion exchange membrane water electrolysis (AEMWE) enables low‐cost green hydrogen production but remains limited by the delicate balance among ionic resistance, gas crossover, and mechanical durability in hydrocarbon‐based membranes. Although reinforced composite membranes (RCMs) alleviate this limitation, conventional expanded polytetrafluoroethylene (ePTFE) reinforcements suffer from fluorocarbon–hydrocarbon interfacial incompatibility, resulting in incomplete ionomer impregnation. We report a plasma‐modified polyethylene (PE) reinforcement that promotes hydrocarbon ionomer infiltration within dense submicron pores. Oxygen plasma treatment introduces polar functional groups on the PE surface, enhancing wettability and capillary‐driven impregnation without altering morphology. The plasma‐treated PE‐based RCM achieves high strength, low swelling, and reduced hydrogen crossover, exhibiting a crossover current density of 0.133 mA cm−2 at ∼30 µm thickness, over fourfold lower than a non‐reinforced membrane. Under practical operation, the anode hydrogen concentration remains well below the explosion safety limit, while the AEMWE performance is comparable to an optimized alcohol‐mediated PTFE‐based RCM, despite its denser pore structure. A membrane selectivity factor coupling ohmic resistance and hydrogen crossover quantifies this balance. The plasma‐treated PE‐based RCM exhibits the highest membrane selectivity factor, 3.26‐ and 2.26‐fold higher than the non‐reinforced and ePTFE‐reinforced membranes, respectively. Continuous operation for 1000 h at 1.0 A cm−2 confirms long‐term durability.