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.