Unveiling and identifying the overlooked fluoride hazard derived from spent lithium-ion battery recovery

The environmental hazards of polyvinylidene fluoride (PVDF) binder during lithium-ion battery (LIB) recycling are remain insufficiently characterized. Despite its low content in cathodes, PVDF's considerable global consumption and inadequately characterized pyrolysis pathways contribute to growing environmental fluoride burdens. In this study, through experimental investigation and modeling analysis, we address several critical problems of PVDF pollution from LIBs, and clarify its pollution characteristics. We overcome the challenge of detecting low-content PVDF in LIBs by establishing a response mechanism and clarifying its real-world removal properties. Thermogravimetric analysis coupled with in-situ FTIR-MS identifies toxic gaseous fluorides (HF, CH₃F, C₂H₂F₂, and C₆H₃F₃) produced from PVDF pyrolysis. Kinetic analysis confirms a random nucleation-growth mechanism which follows the Avrami-Erofeev equation, while DFT calculations elucidate three pyrolysis pathways via electrophilic attacks on fluorine and C-C bonds. Projections estimate global gaseous fluoride emissions from PVDF pyrolysis will surge from 3.10 kt (2025) to 19.74 kt (2040), highlighting underlying pollution in current LIB recycling practices. This work underscores the urgent need for PVDF-specific emission controls to ensure sustainable LIB recycling.