Starch gel for flexible rechargeable zinc-air batteries

Flexible zinc (Zn)-air batteries are recognized as a next-generation battery candidate for emerging smart-wearable devices in portable use. Unfortunately, the high cost of flexible electrolytes and the complex synthesis process limit the commercial application of flexible Zn-air batteries. Here, we report a cost-effective starch gel fabricated through the starch gelation reaction for flexible Zn-air batteries. Benefiting from excellent hydrophilicity and adhesion, the prepared starch gel electrolyte exhibits a high ionic conductivity of 111.5 mS cm⁻¹, leading to the close contact between the electrolyte and the electrodes. Moreover, a flexible Zn-air battery with the starch gel electrolyte delivers a long large cycling number of >200, a peak power density of 84 mW cm⁻², extraordinary mechanical flexibility, and rugged reliability under complex conditions. Our work offers a strategy for the design and construction of high-performance solid-state electrolytes for flexible Zn-air batteries.