Porous covalent organic frameworks for high transference number polymer-based electrolytes

While solid polymer electrolytes are poised to be the key component of next-generation solid-state batteries, the low Li+ transference number of the polymer electrolytes limits their practical applications. Here, porous boron-containing covalent organic frameworks with different surface areas were synthesized and employed as functional additives for enhancing the Li+ transference number of the polymer electrolytes. The boron-containing frameworks enable strong adsorption of the anions of the lithium salt, leading to a significantly enhanced Li+ transference number of the polymer electrolyte containing COF additives. It is observed that solid-state cells assembled with the COF-containing polymer electrolytes exhibited remarkably decreased overpotentials and enhanced rate performances, which opens up new ways to apply porous organics in next-generation solid-state batteries.