Synergistic optimization of porous composite separators for advanced alkaline water electrolysis

Alkaline water electrolysis (AWE) is a key technology for green hydrogen production, but its performance is limited by porous separators that require a balance of high ionic conductivity, low gas permeability, and alkaline stability. Herein, polysulfone-based composite separators with ZrO 2 nanoparticles and various porogens (PVP and PEG) were fabricated via non-solvent induced phase separation combined with a pre-evaporation step. The effects of nanoparticle size, porogen type and molecular weight, and pre-evaporation time on membrane properties were systematically examined. The optimized Z100-P1-T1 separator (100 nm ZrO 2 , PVP, 1 min pre-evaporation) exhibited high porosity, low area resistance, bubble point pressure >3 bar, and enhanced mechanical strength. In a zero-gap electrolysis cell at 80 °C and 2000 A m −2 , it showed a degradation rate below 0.5 mV h −1 over 200 h, indicating promising operational stability under the tested conditions. This work offers a viable strategy for designing high-performance separators for AWE.