Gelatin-based gel polymer electrolytes with high ionic conductivity for temperature adaptive flexible zinc-air batteries

Zinc-air batteries (ZABs) have gained increasing attention due to their high energy density and environmental sustainability. However, challenges such as dendrite formation on zinc anodes in flexible ZABs, particularly under highly alkaline conditions, have hindered their performance. In this study, we introduced a simple and effective approach to design a double-network gel polymer electrolyte (GPE) composed of polyacrylamide (PAM) and gelatin (PAG). The helical structure of the gelatin network facilitated uniform zinc ion transport, while the polar groups in PAG stabilized water molecules, reducing evaporation and freezing. Notably, the PAG GPE retained over 57 % of its water content after 240 h of air exposure. The ZABs incorporating the PAG GPE exhibited superior ionic conductivity (215 mS·cm⁻¹) and an impressive maximum specific capacity of 737 mAh·g⁻¹. Compared to PAM-only GPEs, the PAG-based batteries showed a 1.68-fold improvement in cycle life. Furthermore, the PAG GPE-based ZABs maintained exceptional stability over a wide temperature range from −40 °C to 60 °C, with an extended cycling lifespan of 140 h at −40 °C. These results underscored the suitability of PAG GPE for applications in extreme environments. Experimental results and simulations confirmed that the PAG GPE effectively promoted uniform zinc ion deposition, significantly suppressing dendrite growth. This innovative hydrogel electrolyte, integrated into flexible ZABs, provided a robust solution for next-generation flexible electronics.