Zinc-air batteries (ZABs) have emerged as sustainable alternative energy storage systems. However, electrolyte evaporation remains a critical limitation that restricts their cycling stability and practical deployment. Quasi-solid electrolytes (QSEs) have been proposed to mitigate this issue by retaining liquid electrolytes; nevertheless, conventional QSEs for ZABs are commonly fabricated with thicknesses in the millimeter range (typically 2¿5 mm), increasing the electrode separation distance and potentially compromising the volumetric performance of the device. Herein, we report the synthesis of ultrathin electrospun QSEs based on poly(vinyl alcohol) (PVA) and potassium polyacrylate (PAAK), a superabsorbent polymer, and compare their properties with those of a conventional electrospun PVA¿PAA (polyacrylic acid) QSE. The porous architecture generated by electrospinning, combined with the high electrolyte affinity of PAAK, resulted in an ionic conductivity of 144 mS cm¿¹, a KOH uptake of 974%, and a narrow surface potential distribution, as revealed by scanning Kelvin probe microscopy (SKPM). Despite the high electrolyte uptake, the PVA¿PAAK QSE exhibited reduced dimensional changes upon hydration, showing 51% lower areal expansion and 47% lower swelling than the PVA¿PAA counterpart. The resulting QSE, with a thickness of approximately 200 µm, delivered a specific areal capacity of 24.1 mA h cm¿² and sustained 147 charge-discharge cycles in a flexible zinc-air battery configuration. In addition, the assembled batteries remained electrochemically operational after direct flame exposure and water immersion tests. Following 1200 s of water immersion, the battery retained an open-circuit voltage of 1.58 V and a round-trip efficiency of 64.8%.
