−60 to 50 °C ultrawide-temperature flexible zinc–air batteries enabled by a ternary polar hydrogel electrolyte

Abstract

Flexible zinc–air batteries (FZABs) capable of operating across a broad temperature range are highly desirable for powering next-generation wearable electronics. However, FZABs still suffer from unsatisfactory performance under extreme temperature conditions, primarily due to the restricted ion transport caused by the freezing and dehydration of the hydrogel electrolytes (HEs). In this work, a new ternary polar hydrogel electrolyte composed of polyacrylamide, poly(sodium-p-styrenesulfonate) and ethylenediaminetetraacetic acid tetrasodium salt (PAM–PSS–EDTA HE) has been developed for ultrawide-temperature FZABs. Benefiting from the unique synergistic effect of the ternary polar functional groups in the PAM–PSS–EDTA HE, stronger and more numerous hydrogen bonds between water and the functional groups are formed, leading to enhanced anti-freezing and water-retention properties. The PAM–PSS–EDTA HE exhibits high ionic conductivities of 348 mS cm⁻¹ at 25 °C and 50.2 mS cm⁻¹ at −60 °C, excellent anti-freezing performance with the freezing point below −100 °C, and outstanding water-retention ratios of 83.4% after 200 hours at 25 °C and 77% after 100 hours at 50 °C, demonstrating a significant superiority over single or double component HEs. Furthermore, FZABs based on the PAM–PSS–EDTA HE and NiFe-OLC electrocatalyst demonstrate excellent performance in an ultrawide temperature range of −60 °C to 50 °C, and exhibit ultralong cycle lives of 4000 cycles at −60 °C and 400 cycles at 50 °C. This work offers valuable insights for the development of high-performance hydrogel electrolytes for wide-temperature FZABs.