74 µm PEEK‐Reinforced Sulfonated Poly(phenylene sulfone)‐Membrane for Stable Water Electrolysis with Lower Gas Crossover and Lower Resistance than Nafion N115

Abstract

Polymer electrolyte membrane (PEM) water electrolysis is a crucial technology for green hydrogen production. Hydrocarbon membranes are drawing a lot of attention due to potentially superior properties and the fact that common fluorinated polymers might face a potential ban. This study introduces a sulfonated poly(phenylene sulfone) (sPPS) membrane, reinforced with a poly(ether‐ether‐ketone) (PEEK) mesh. The reinforced membrane induces a drastic increase in dimensional stability, enabling direct anode casting—an essential step toward industrial manufacturing. It further exhibits a significant reduction in water uptake (115% vs 294% for pure sPPS) and a 40% lower H2‐crossover (0.18 mA cm−2) compared to the industry standard N115 (0.31 mA cm−2). Due to the lower thickness (74 vs 127 µm) and higher ion exchange capacity (IEC)(1.92 vs 0.89 mmol g−1), the PEEK‐sPPS membrane displays a substantially lower resistance (70 vs 159 mΩ cm2 for N115). This directly translates into a voltage reduction of ≈90 mV at 1 A cm−2 or ≈180 mV at 2 A cm−2, both typical operating current densities. Finally, PEEK‐sPPS exhibits the longest lifetime shown for hydrocarbon membranes with almost 650 h at 1 A cm−2 and a low degradation rate (80 µV h−1).

Best Practices in Membrane Electrode Assembly for Water Electrolysis

“…Severin et al introduced membrane reinforcement technologies by mixing sulfonated poly(phenylene sulfone) (sPPS) membrane and polyether ether ketone (PEEK) mesh (Table 2). 208 The PEEK mesh was expected to provide chemical and mechanical reinforcement to the sPPS membrane as well as beneficial compatibility and interaction. The sPPS membrane was cast on PET foil or a glass plate using a bar-coater, and the PEEK mesh was directly cast onto the membrane using a Mayer rod with an 80 μm gap size.…”