Morphological tuning-driven high-performance separator for alkaline water electrolyzer through the surface modification of mechanical support

Porous separators-based alkaline water electrolyzers (AWEs) have been recently highlighted due to the cost-effective hydrogen production without carbon emission. However, the low bubble point pressure (BPP) and ionic conductivity of the commercial separator cause safety issues and low energy efficiency in renewable energy source-coupled AWE, respectively, and they are in typical trade-off relation associated with pores where both electrolyte and gas pass through. Traditional approaches to address these issues have encountered limitations for further improvement. In this study, we focus on investigating the interaction between the surface of reinforced support and polymer binder. The surface of the reinforced support was modified via the sulfonation process by which, hydrogen bonding and hydrophilic attractions are induced between mesh and ZrO₂/polysulfone composites. Importantly, small angle X-ray scattering analysis supports that those interactions derive highly interconnected nano/macro-pores of separators without defective sites, affording great pathways for electrolyte and interference for gas at the same time. The optimized sulfonated reinforced mesh-incorporated separator breaks the intrinsic drawback of performance trade-off while exhibiting the highest level of membrane characteristics (e.g., BPP of 6.6 bar and area resistance of 0.12 Ω cm²) as compared with other state-of-the-art porous separators as well as exhibiting high-performance and stable cell performances of AWE (e.g., 2 V @ 2 A cm⁻² with Raney Ni/NiFe LDH at 80 °C, 30 wt% KOH). This finding could enlarge the potential for the further development of porous separator-based AWE, rendering the next-generation AWE with high current density and safety.