Temperature-Adaptive Aqueous Zinc–Iodine Batteries Enabled by Ionic Covalent Organic Framework Modified Separator

Zinc–iodine batteries (ZIBs) face challenges, such as polyiodide shuttling, self-discharge, and temperature sensitivity. To overcome these issues, we developed a separator functionalized with an ionic covalent organic framework (COF@GF), which incorporates pyridine quaternary ammonium active sites. The COF@GF separator enhances ionic conductivity (13.9 mS cm –1 ) and Zn 2+ transference number (0.76), suppresses anode dendrite formation, and reduces self-discharge. In situ Raman spectroscopy and theoretical calculations show that COF’s moderate electronic conductivity improves I 3 – /I 5 – conversion kinetics and enhances polyiodide adsorption through Lewis acid–base interactions, thus controlling redox chemistry and suppressing shuttle effects. COF@GF-modified ZIBs exhibit stable cycling for over 5000 cycles at 20 C and perform well across temperatures from −5 to 60 °C. At 0 °C, the battery retains 89.6% of its capacity over 10000 cycles, with a minimal decay rate of 0.001% per cycle, showcasing the potential of ionic COF materials for practical aqueous ZIB applications.