Nitrogen-rich redox-active monomers for COF battery materials (NITROCOF)

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Covalent organic frameworks (COFs) are a versatile platform for achieving high-performance organic electrode materials. Redox-active subunits are readily installed and their porosity allows for efficient ion diffusion. However, most reported COFs as electrode materials use an n-type redox activity, meaning that electrons are reversibly stored concurrently with the insertion of metal cations from the electrolyte for charge balancing. In this joint proposal, we will systematically study the effect of nitrogen enrichment in the redox-active units incorporated in 2D-COFs. Two main advantages are proposed when enhancing the nitrogen heteroatom content: 1) reversible redox processes with multiple electron transfers as p-type materials can be addressed, and 2) improved coordination by N-heteroatoms to counterions for better ion storage. Hence, the enrichment of N-heteroatoms in aromatic subunits of COFs will be studied in relation to their electrode performance in lithium- or magnesium-based batteries. The synthesis of novel 2D-COFs (Dumele group) and selected linear amorphous polymers (Esser group) bearing directly comparable redox-active units will be achieved within this SPP project. We envision revealing fundamental charge and radical stabilization mechanisms using various nitrogen-enriched patterns and structure motifs. This joint approach to COF-based electrode materials will help to design polymeric scaffolds for energy storage devices fundamentally.