Low hydrogen crossover anion-exchange membrane water electrolysis based on non-ionic binder polymers

Abstract

The quest for high energy efficiencies pushes anion-exchange membrane water electrolysers (AEMWE) to adopt designs comprising highly-functionalised catalyst/ionomer electrodes. Unfortunately, undesirably high hydrogen crossover owing to such ionomer-based electrodes has so far gone unnoticed. Here, we report on AEMWE cells employing non-ionic fluorine-free binder polymers. The hydrophobic electrodes expel liquid electrolyte from transport pathways, thereby reducing hydrogen supersaturation pressures. As a result, hydrogen crossover is multifold reduced (down to 0.8% at 2 A cm−2). Strikingly, even the electrolyser overpotential is reduced by 40 mV compared to the anion-exchange ionomer owing to facile gas transport, affording electrolyser loads of 1.5 A cm−2 at 1.88 V at 60 ◦C. The non-ionic cathodes show durability beyond 1000 hours and operate in dual-feed as well as in dry-cathode mode. The introduced design allows to select electrode materials from a much greater library, with the anticipated result of new generations of durable electrodes for water electrolysers and beyond.