Enhancing performance and longevity of solid-state zinc-iodine batteries with fluorine-rich solid electrolyte interphase

Rechargeable zinc-iodine (ZnI₂) batteries have gained popularity within the realm of aqueous batteries due to their inherent advantages, including natural abundance, intrinsic safety, and high theoretical capacity. However, challenges persist in their practical applications, notably battery swelling and vulnerability in aqueous electrolytes, primarily linked to the hydrogen evolution reaction and zinc dendrite growth. To address these challenges, this study presents an innovative approach by designing a solid-state ZnI₂ battery featuring a solid perfluoropolyether based polymer electrolyte. The results demonstrate the formation of a solid electrolyte interphase layer on zinc, promoting horizontal zinc growth, mitigating dendrite penetration, and enhancing battery cycle life. Moreover, the solid electrolyte hinders the iodine ion shuttle effect, reducing zinc foil corrosion. Symmetric batteries employing this electrolyte demonstrate excellent cycle performance, maintaining stability for approximately 5000 h at room temperature, while solid-state ZnI₂ batteries exhibit over 7000 cycles with a capacity retention exceeding 72.2%. This work offers a promising pathway to achieving reliable energy storage in solid-state ZnI₂ batteries and introduces innovative concepts for flexible and wearable zinc batteries.