Developing a PFAS-Free Binder Compatible with Green Solvents for Organic Cathodes

Organic cathode materials are promising candidates for sustainable energy development due to their ready accessibility and structural diversity compared with inorganic materials. However, the widely used commercial binder polyvinylidene fluoride (PVDF) is a polyfluoroalkyl substance (PFAS) that generates persistent fluorocarbon waste. Furthermore, PVDF is not ionically conductive, which limits its effectiveness in organic electrodes. The solvent, N-methyl-2-pyrrolidone (NMP), which is broadly used in the fabrication of organic electrodes, also presents significant drawbacks, including health risks and high energy demands during fabrication due to its high boiling point. In this study, we report a green binder-solvent combination for organic cathode materials. A sustainable, novel polyether dopamine polymer binder (PDO) with an ion-conductive backbone and dopamine pendant groups is developed as a sustainable alternative to PVDF. The polymer can be synthesized on the gram scale with facile modification. Following binder synthesis, we investigated several green solvents in combination with PDO to develop a greener processing method for organic cathode materials. Preliminary electrochemical testing in aqueous zinc-ion batteries with two commonly used carbonyl-based cathode molecules demonstrates that the PDO-GS system outperforms the conventional PVDF-NMP system. Mechanistic studies revealed enhanced ion charge transfer in electrodes prepared with PDO-GS. These findings emphasize the potential of PDO-GS as a sustainable performance-enhancing binder and solvent system for organic cathodes.