Key Takeaways & Executive Findings
- •• • NMP release is highest during coating/drying in production and during electrolyte volatilization and pyrolysis in disposal; at 150°C in air, NMP concentrations reached 169 μg/g in gas phase for polymer batteries, indicating significant volatilization risk. • • Under N2 pyrolysis at 850°C, NMP was completely degraded in solid residues (0 μg/g) but remained in gas phase (7.24 μg/g for ternary batteries), demonstrating incomplete thermal destruction and potential emission. • • Occupational exposure via dust ingestion in unprotected settings exceeds reference doses, highlighting the need for engineering controls and personal protective equipment in battery recycling facilities. • • The study establishes a mass balance for NMP across thermal treatment temperatures, showing that lower temperatures (150°C) favor volatilization while higher temperatures (≥550°C) lead to thermal decomposition, but gas-phase residues persist.
Abstract
The production and disposal of lithium batteries release not only hazardous metals and particulates but also substantial amounts of harmful organic pollutants. This study focuses on N-methyl-2-pyrrolidone (NMP) to investigate the environmental release and human exposure of organic pollutants throughout the lithium battery lifecycle. Using liquid chromatography-high-resolution mass spectrometry (LC-HRMS), NMP was quantified in environmental samples from battery production and dismantling facilities, as well as in pyrolysis products from simulated thermal recovery of mainstream lithium batteries. Key release stages were identified: slurry mixing and coating/drying during production; shredding, electrolyte volatilization, and high-temperature pyrolysis during disposal. In unprotected occupational settings, estimated NMP exposure via dust ingestion exceeded reference doses, underscoring the need for health impact assessments and evaluation of protective measures. This research provides critical insights into the environmental release and population exposure of organic pollutants across the lithium battery lifecycle, informing health policy for vulnerable populations.
1. Introduction
The rapid expansion of lithium battery production for clean energy storage and carbon neutrality goals has introduced new environmental and health challenges. While metal contamination (Ni, Co, Li) is well-documented, organic components such as electrolytes, flame retardants, binders, and separators also pose risks. N-methyl-2-pyrrolidone (NMP), a solvent used in electrode binder dissolution, is particularly concerning due to its volatility and toxicity, including reproductive and developmental effects. Although Chinese regulations mandate >90% NMP recovery during drying, its high volatility leads to inevitable environmental release. Existing detection methods have focused on consumer products, leaving a gap in understanding NMP release during battery lifecycle processes.
This study addresses that gap by combining field monitoring and laboratory simulations to quantify NMP release across production and disposal stages. Using LC-HRMS, we analyzed environmental samples from battery facilities and simulated thermal recovery processes. Our findings identify critical control points and reveal that occupational exposure via dust ingestion can exceed reference doses, emphasizing the need for targeted interventions. This work provides a scientific basis for managing NMP emissions and protecting worker health, while also serving as a reference for other organic pollutants in battery recycling.
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GAO Wei, LI Wenxuan, SUN Jie, LIU Yaojun, XIN Shanzhi, LIN Yongfeng, WEI Juntong, ZHENG Yuxin, WANG Yawei (2026). Release Characteristics of Organic Pollutants and Occupational Exposure During Lithium Battery Production and Disposal: A Case Study on N-Methylpyrrolidone. Environmental Chemistry. https://doi.org/10.7524/j.issn.0254-6108.2025010203
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Frequently Asked Questions
What are the dominant release pathways of NMP during lithium battery production and disposal, and how do they vary with temperature and atmosphere?
During production, NMP is primarily released during slurry mixing and coating/drying. In disposal, shredding and electrolyte volatilization are key, with high-temperature pyrolysis (≥550°C) leading to thermal decomposition. At 150°C in air, gas-phase NMP concentrations reached 169 μg/g for polymer batteries, while at 850°C under N2, solid residues contained no NMP but gas-phase concentrations remained (7.24 μg/g for ternary batteries), indicating incomplete destruction.
What is the estimated occupational exposure risk for workers in unprotected settings, and how does it compare to reference doses?
The study found that NMP exposure via dust ingestion in unprotected occupational settings exceeds reference doses, indicating a potential health risk. This underscores the need for effective personal protective equipment and engineering controls in battery recycling facilities.
How does the NMP concentration in solid residues and gas phases change across different thermal treatment conditions?
At 150°C, NMP remains in both solid and gas phases (e.g., 10.4 μg/g solid and 37.5 μg/g gas for ternary batteries in air). At 550°C and above, solid residues contain no NMP, but gas-phase concentrations vary (e.g., 12 μg/g at 550°C in air for ternary batteries, 73.9 μg/g at 550°C under N2 for polymer batteries). At 850°C, gas-phase NMP is lower (0-7.24 μg/g), indicating more complete degradation but not zero emission.
What are the implications of these findings for designing safer battery recycling processes?
The results suggest that thermal treatment at higher temperatures (≥550°C) can effectively remove NMP from solid residues, but gas-phase emissions require capture and treatment. Lower temperatures (150°C) lead to significant volatilization, necessitating closed-loop systems and efficient ventilation. Process modifications should focus on minimizing NMP release during shredding and electrolyte handling, and implementing gas treatment technologies.
How does this study contribute to the broader understanding of organic pollutant emissions from lithium batteries?
By providing a comprehensive analysis of NMP release across the lifecycle, this study establishes a methodological framework for assessing other organic pollutants (e.g., electrolytes, flame retardants). It highlights the need for monitoring and controlling volatile organic compounds in battery recycling, contributing to environmental and occupational health policy development.
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