Thermal fate of polyvinylidene fluoride (PVDF) binders in lithium-ion battery recycling: Implications for PFAS and fluorinated degradation products.

The global transition toward renewable energy has accelerated the demand for lithium-ion batteries (LIBs), which are essential for energy storage, electric vehicles, and portable electronics. Battery recycling has become a strategic priority to recover critical materials and minimize waste. The presence of fluorinated binders, particularly poly(vinylidene fluoride) (PVDF), poses significant operational and potential environmental challenges. PVDF binder offers exceptional chemical stability but complicates its thermal removal during battery recycling, potentially generating toxic fluorinated emissions. Despite the widely used pyrometallurgical battery recycling processes, the thermal decomposition and emission profiles of the PVDF binder within spent LIBs metrics remain poorly understood. We investigated the thermal degradation of PVDF and cathode materials under representative recycling conditions. Our results revealed the generation of a diverse spectrum of fluorinated volatile, condensed, and solid-phase products whose composition varied with temperature, oxygen availability, and cathode chemistries. We identified key temperature thresholds associated with LIBs material breakdown and the subsequent formation of fluorinated alkanes, aromatic substances, and oxygenated hydrocarbons. The findings provide new molecular-level insights into the thermal fate of PVDF during battery recycling and the mechanistic understanding of fluorinated degradation product formation, supporting the development of safer and more sustainable battery recycling strategies.