Bollard-Anchored Binder System for High-Loading Cathodes Fabricated via Dry Electrode Process for Li-Ion Batteries.

Abstract

The dry battery electrode (DBE) process offers significant advantages over conventional wet-coating methods for electrode fabrication. Unlike traditional processes that rely on toxic solvents such as N-methyl-2-pyrrolidone (NMP), the DBE technique uses solvent-free methods, reducing environmental impact and production costs while enhancing compatibility and performance. However, polytetrafluoroethylene (PTFE), the only binder currently used for large-scale DBE fabrication (binder fibrillation), faces potential regulatory restrictions under Polyfluoroalkyl Substances (PFAS) guidelines and limits Li-ion conductivity, elastomeric properties, and particle adhesion. This study explores a novel dual-binder system, termed the "bollard hitch" model, designed to overcome these limitations as the first PTFE-less binder for binder fibrillation. Poly(acrylic acid)-grafted sodium carboxymethyl cellulose (PC) acts as the "bollard," strongly attaching to the PTFE "anchor." This binder system reduces PTFE usage by over 70% and enables the fabrication of high-mass loading cathodes (up to 90 mg cm^{- 2}, 15.6 mAh cm^{- 2}) with superior performance. It enhances ionic conductivity and mechanical strength, making it suitable for high-voltage applications and offering great potential to revolutionize the manufacturing of high-performance, durable energy storage systems.