High-Resolution Mass Spectrometry-Based Suspect and Nontarget Screening of Organophosphate/Organofluorophosphate Esters in Spent Ternary Lithium-Ion Power Batteries

Organophosphate/organofluorophosphate esters (O(F)PEs) in spent lithium-ion power batteries (LIPBs) may pose environmental and occupational health risks. In this study, we conducted suspect and nontarget screening using high-resolution mass spectrometry to characterize O(F)PEs in spent ternary LIPBs. Using diagnostic fragment ions at m/z 98.9837, 78.9587, and 98.9648, etc., we identified 41 O(F)PEs (tri/di/mono-OPEs, cyclic OPEs, OFPEs), including 14 first-reported compounds (confidence level ≥ 3). These compounds were ubiquitously detected across 16 spent ternary LIPB packs, indicating their pervasive occurrence. The predominant compounds–trimethyl phosphate, dimethyl hydrogen phosphate, and fluoro(methoxy)phosphinic acid–were found at concentrations up to 105 ng/g. Aging experiments demonstrated that unused LIPB cells already contained O(F)PEs, with their formation accelerated by electrochemical cycling and thermal aging, indicating the continuous accumulation of O(F)PEs during battery operation. Further environmental risk assessment reveals that O(F)PEs exhibit high mobility, indicating their potential for environmental diffusion. Health risk ranking based on absorption, distribution, metabolism, excretion, and toxicity parameters prioritized 1-[fluoro(propoxy)phosphoryl]oxypropane and 1-[ethoxy(fluoro)phosphoryl]oxypropane for occupational health monitoring. This study reveals that spent ternary LIPBs are a non-negligible source of diverse O(F)PEs, highlighting potential risks in recycling and informing necessary risk assessments.