Processable and Recyclable Covalent Organic Framework Gel Electrolytes.

Abstract

Covalent organic framework (COF)-based electrolytes with abundant ordered channels and accessible interaction sites have shown great potential in energy storage and transformation, although their practical applications are strongly impeded by their inherent insolubility and non-melt processability. Developing processable COF gel electrolytes and recycling them remains a formidable challenge. In this study, the processing of COF to gels demonstrated through interlayer interaction manipulation and enable solution-reconstruction of COF gel electrolytes for the first time, inspired by the working principle of wedges. Good solution-processability of the COF powders in strong acid mediums is achieved by inserting oxygen atoms into its framework to promote the interlayer charge repulsion. This modification enabled the COF readily dispersable as colloidal nanosheets in an aqueous solution of trifluoroacetic acid (TFA). Starting from here, this is modulated competitive interactions among TFA, COF, and water molecules, to reconfigure COF materials between their gelified and colloidally dispersed states. The reconfigured COF gel maintains their mechanical properties and long cycle life as an electrolyte in the battery (>800 h). This approach realizes solution processing of COF powders and can recycle COF out of gels for repeated use, offering new insights and strategies for their preparation and sustainable recycling.