A Comparison of Static and Dynamic Headspace for Extracting Residual NMP from Lithium-Ion Battery Cathodes

Lithium-ion batteries (LIBs) are widely used in consumer electronics and electric transportation due to their high Energy densities, long life cycles, and fast-charging capabilities. During cathode manufacturing, N-methyl-2-pyrrolidone (NMP) is a critical solvent used to disperse electrode components to form a uniform coating. Although NMP is removed during drying, residual levels can compromise the electrode, negatively affecting battery performance, and pose significant Health and environmental risks to battery manufacturers, given ist ability to cause whole-body exposure at low concentrations. Existing methods for determining residual NMP typically require ultrasound-assisted extraction with organic solvents, thereby increasing sample preparation time and complexity. Static headspace (SHS) is frequently used for residual solvent Analysis due to its simplicity and minimal sample preparation. However, its equilibrium-based nature is limited for trace-level detection. In this work, SHS and dynamic headspace (DHS) extraction methods were compared for the determination of trace NMP in LIB cathodes. DHS continuously purges and enriches volatiles onto a sorbent-filled tube, enabling substantially lower detection limits than equilibrium-based SHS. A DHS calibration curve was generated to quantify residual NMP on cathodes with differing active materials.