Anthraquinone Covalent Organic Frameworks Hollow Tubes as Binder Micro-Additives in Li-S Battery

The exploration of new application-forms of covalent organic frameworks (COFs) in Li-S batteries that can overcome the drawbacks like low-conductivity or high loading when typically applied as sulfur host-materials (mostly ~20 to ~40 wt% loading in cathode) is desirable to maximize their low-density advantage to obtain lightweight, portable or high energy-density devices. Here, we establish that COFs could have implications as micro-additives of binders (~1 wt% in cathode), and a series of anthraquinone-COF based hollow-tubes have been prepared as model micro-additives. The micro-additives can strengthen the basic properties of binder and spontaneously immobilize and catalytically convert lithium-polysulfides as proved by the density functional calculations, thus showing almost doubly enhanced reversible capacity compared with that of the bare electrode. Correlating the COFs with their high functionality and porosity, as well as their new application-forms of micro-additives with boosted performances, could provide new insights to conquer the fundamental challenges in Li-S batteries.