Highly Processable and Adhesive PFAS-Free Bottlebrush Copolymer Binder for Dry Electrode Fabrication

Dry electrode manufacturing offers a solvent-free and streamlined pathway toward high-mass-loading electrodes. However, the widespread use of conventional polytetrafluoroethylene (PTFE) binders raises critical environmental concerns due to per- and polyfluoroalkyl substances (PFAS). Herein, we present an eco-friendly, PFAS-free bottlebrush polymer binder synthesized through a combination of atom transfer radical polymerization (ATRP) and ring-opening metathesis polymerization (ROMP). Designed with poly(acrylic acid) (PAA) and poly(methyl acrylate) (PMA) side chains, this unique-structured binder ensures adhesion and conductive additive affinity via hydrogen bonding and CH-π interactions. Notably, the sterically hindered bottlebrush architecture effectively suppresses chain entanglement, reducing melt viscosity for enhanced processibility. As a result, mechanically robust dry electrodes were successfully fabricated with reduced binder content, and superior adhesion and stable electrochemical performance were verified by mechanical and electrochemical tests.