Alkaline sodium polyacrylate-starch hydrogels with tolerance to cold conditions for stretchable zinc-air batteries

With the advancement of wearable electronic devices, it is critical to create a flexible power source that is high performing, cost effective, and safe. The flexible zinc-air battery as a promising candidate has been widely concerned, while most hydrogel electrolytes lose their stretchability in a strong alkaline environment. Herein, a sodium polyacrylate-starch double-network hydrogel is prepared by simple solution copolymerization and swelling techniques. Not only does the hydrogel exhibit exceptional mechanical strength, toughness, and ionic conductivity, but it also exhibits an exceptional freezing-tolerance capability. The stretchable zinc-air battery with sandwich construction has a high energy efficiency of 68%, a high energy density of 67.5 mW cm−2, and a high degree of dependability in stretched modes. Additionally, the battery performs well mechanically and electrochemically at a cold environment (−20 °C). The batteries can be incorporated into a range of energy-consuming gadgets, suggesting that they are very practicable as wearable power sources.