Enhanced Low-Temperature\nDurability of Flexible Zinc–Air\nBatteries Using NaCl-Doped Dual-Network Hydrogel Electrolytes

With the rapid development of flexible wearable devices,\nthe demand\nfor advanced energy storage systems has significantly increased. Flexible\nzinc–air batteries (ZABs) are promising candidates due to their\nlow cost and high energy density. However, their performance in low-temperature\nenvironments has been a significant challenge. In this study, we introduce\na dual-network hydrogel electrolyte composed of sodium polyacrylate\nand polyacrylamide (PANa-M), further enhanced with sodium chloride\n(NaCl) to form PANa-M–NaCl. The inclusion of NaCl significantly\nstrengthens the hydrogel’s mechanical durability, enabling\nit to withstand extreme conditions like bending, twisting, and squeezing.\nBeyond its structural benefits, NaCl also enhances the hydrogel’s\nlow-temperature performance by improving water retention, accelerating\nelectrochemical reaction kinetics, and lowering the electrolyte’s\nfreezing point. Moreover, NaCl mitigates side reactions on the zinc\nelectrode, further stabilizing battery operation under harsh conditions.\nAs a result, PANa-M–NaCl-based ZABs demonstrate a power density\nof 85.3 mW/cm<sup>2</sup> and sustain a charge–discharge cycle\nlife exceeding 105 h at room temperature. More importantly, at −30\n°C, the ZABs maintain excellent performance with over 250 h of\ncharge–discharge cycles, highlighting the effectiveness of\nNaCl in improving electrolyte concentration and stabilizing the gel\nstructure at subzero temperatures. This study presents a simple and\neffective strategy to enhance the durability and performance of flexible\nZABs in challenging low-temperature environments, paving the way for\nbroader applications in wearable technology.