Battery Production Solvent Alternative to NMP - Jeffsol® MEOX

Solvents are commonly used in in battery manufacturing to dissolve binders, aid in slurry dispersion, stability, and the coating process [1]. For the cathode, N-Methylpyrrolidone (NMP) is the commonly used solvent for working with PVDF binder. However, it has been classified as Reprotoxic, and labeled as a CMR substance. Due to the classification, there are existing strict emission regulations and increasing regulations on the handling and use of the solvent [1,2]. As a result of these regulations with NMP, there has been increased interest for replacements that can improve the safety without significantly affecting the existing processes. Huntsman has developed JEFFSOL® MEOX, a solvent which may be less hazardous to handle while having similar performance capability to NMP. JEFFSOL® MEOX and NMP are both clear, colorless, and odorless aprotic solvents. They also share similar dipole moments and dispersion energy parameters . Therefore, JEFFSOL®MEOX may have an advantage in solubility performance in some applications when compared with other NMP alternatives (Table 1). Due to these comparable characteristics and the ease of handling, JEFFSOL® MEOX can be used in a wide variety of applications. In addition to use as a solvent for PVDF or PAN binders in batteries, JEFFSOL® MEOX can be applied in chemical reactions and polymerization applications [3]. Due to its usefulness in multiple markets, there are multiple grades of MEOX available, including E-Grade® MEOX which contains ultra-low metals and can be used in semiconductor production without contaminating the wafer. As an example of the comparable solubility performance, Figure 1 shows results of NMP and JEFFSOL® MEOX with multiple PVDF samples that are commonly used in battery production, including mono- and co-polymers of low and high molecular weights. With both solvents, heat and agitation decreased the time needed to fully dissolve the PVDF. In addition to MEOX, Huntsman offers other experimental solvents which could be used as NMP replacements as well. In addition to the range of solvents currently offered, Huntsman has the capability to synthesize new solvents based on user feedback. This Huntsman technology gives users greater flexibility and capabilities in selecting the ideal solvent for their unique processes while shifting away from NMP. This presentation shows the latest results with JEFFSOL®MEOX benchmarked against industry standard NMP. [1] Y. Liu, R. Zhang, J. Wang, Y. Wang: Current and future lithium-ion battery manufacturing (iScience, Volume 24, Issue 4, 2021) [2] REACH COMMISSION REGULATION (EU) 2018/588 (2018) [3] V. White. H. Zhou, K. Zhang, J. Gazda: Advanced Battery Materials as reported at the International Battery Seminar (2023) Figure 1