Heat-Resistant Covalent Organic Framework (COF) PVA-Hybridized Gel Electrolyte for the Preparation of Dendrite-Free Zinc-Ion Batteries

High-performance zinc-ion batteries (ZIBs) have attracted a great deal of attention due to their high theoretical capacity and high level of safety. Herein, we propose a covalent organic framework (COF) hybrid poly(vinyl alcohol) (PVA)-based gel electrolyte, which can induce the uniform deposition of Zn2+ and achieve dendrite-free formation. By grafting sulfonic acid groups on the surface of COFs to absorb Zn2+, we can strengthen the interaction between strong ions and dipoles in the electrolyte, improve the ionic conductivity, and achieve stable Zn2+ electroplating and stripping. Due to the good thermal stability of the COF material itself, the gel electrolyte hybrid with the PVA hydrogel shows high mechanical strength and good heat resistance and is capable of stable cycling for >1000 h at 50 °C, with a capacity retention rate of ≤75%. This study provides a new approach for developing high-temperature-resistant and highly stable dendrite-free ZIBs.