Delving into different roles of covalent organic frameworks in zinc-ion batteries and zinc-air batteries: A state-of-art review

The zinc (Zn) based battery systems, with unique properties of high reversibility, sustainability, and long-lived ability, have made many breakthroughs during past decades and developed multiple battery types (e.g., ion-type batteries and air-type batteries). By virtue of unique characteristics like high porosity, well-defined structure and designable functionality, covalent organic frameworks (COFs) exhibit intriguing functions in Zn based battery systems. Typically, using COFs as platforms, Zn based battery systems like zinc-ion batteries (ZIBs) or zinc-air batteries (ZABs) have been intensively studied, uncovering the functions from electrode materials, electrolytes, anode modification materials, electrode catalysts to electrode modulators. In this regard, this review focuses on the different roles of COFs in ZIBs and ZABs, summarizes COFs applicable to the two different energy storage systems from the perspective of structure design, electrochemical properties, structure-to-performance relationships as well as important perspectives for future development, aiming at delving into the depth battery mechanisms operated by COFs in ZIBs and ZABs. Considering the commonly existed ion-type and air-type batteries for many battery systems, the summary and discussion about the different roles of COFs in these two typical Zn battery systems would be of broad interest in battery community.