Investigating the Role of the Triple-Phase Boundary in Zinc-Air Cathodes Using Pore Network Modeling

Zinc-air flow batteries are a promising energy storage technology. Their performance depends on their porous cathodes where the oxygen reduction reaction (ORR) occurs. A key feature of cathode is invasion electrolyte, creating so-called triple phase boundary between air, electrolyte and catalyst, which shown in this work to be an overly simplified picture. In study mathematical framework based pore network modeling (PNM) was developed better understand interplay electrode structure, transport species invasion. The results suggest that increasing volume provides highly branched pattern enhances up saturation 0.7 , whereas further reduces air-liquid interfacial area lowers performance. Interestingly, at lower saturations (<0.3) liquid structure so excessively hydroxide ions unable diffuse anode sufficient rate, resulting supersaturation, degradation problem. size distribution catalyst layer also affects with wider distributions generally performing better. This represents first 3D PNM zinc-air includes all physics mechanisms, enabling prediction structure-performance relationship cathodes.