Green Manufacturing of Iron Fluoride/Fluorinated Carbon Nanocomposite Cathodes from PTFE Waste and Iron Oxides via Mechanochemistry

Abstract

Polytetrafluoroethylene (PTFE) waste poses persistent environmental challenges due to its exceptional chemical stability. Meanwhile, the conversion of iron oxides, the major components of abundant natural iron ores, into advanced materials commonly involves multistep processing through refined iron precursors. Herein, we report a closed-loop mechanochemical strategy that integrates PTFE waste upcycling with direct iron oxide fluorination. Compared with conventional iron fluoride synthesis relying on hazardous HF-derived fluorochemicals and refined iron salts, this approach utilizes PTFE waste as a fluorine source and avoids fluoride-containing byproducts. During high-energy ball-milling, mechanochemical activation promotes stable C–F bond cleavage in PTFE and oxygen vacancy generation within the iron oxides. The released fluorine is captured by defect-rich iron oxides to form iron fluoride nanoparticles, while the residual PTFE framework evolves into electrochemically active fluorinated carbon containing reversible semi-ionic C–F bonds. The nanocomposite cathode delivers a capacity of 316.7 mAh g–1 with 70.5% retention after 1000 cycles at 0.25 A g–1, surpassing the one-electron theoretical capacity of FeF3 (237.0 mAh g–1). The enhanced electrochemical performance originates from the synergistic contributions of iron fluoride redox reactions and reversible Faradaic reactions of fluorinated carbon. This work establishes a sustainable manufacturing strategy that transforms persistent fluorochemical waste and abundant iron oxide feedstocks into value-added energy materials.