-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 unsatisfied performance under extreme temperature, 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 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 achieves high ionic conductivities of 348 mS cm^-1 at 25 °C, 50.2 mS cm^-1 at -60 °C, excellent anti-freezing performance with freezing point below -100 °C, and outstanding water-retention ratio of 83.4 % after 200 hours at 25 °C, 77 % after 100 hours at 50 °C, demonstrating a significant superiority over single or double component HEs. Furthermore, FZABs based on PAM-PSS-EDTA HE and NiFe-OLC electrocatalyst demonstrate excellent performance under ultrawide temperature range from -60 °C to 50 °C, and exhibit ultralong cycle lifes 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.