Eco-friendly solvent alternative to N-methyl-2-pyrrolidone in lithium-ion battery electrode safe manufacturing

Abstract

Over the past decade, the rapid growth in lithium-ion battery (LIB) production has been driven by the rising demand for portable electronic devices, electric vehicles, and stationary energy storage systems. However, the widespread use of N-methyl-2-pyrrolidone (NMP) as a solvent in LIB electrode manufacturing poses significant environmental and health concerns. NMP is classified as a reproductive toxicant and is known to cause severe irritation and health risks during the manufacturing process. Accordingly, this study investigates the potential of gamma-valerolactone (GVL), an eco-friendly solvent, and dimethyl sulfoxide (DMSO), a relatively environmentally friendly solvent, as alternatives for NMP in LIB electrode manufacturing. The electrochemical performances of LiFePO₄ cathodes and electrode surfaces were compared and evaluated using NMP-, GVL-, and DMSO-based solvents through field emission scanning electron microscopy (FE-SEM), thermogravimetric analysis (TGA), differential thermogravimetric analysis (DTG), X-ray photoelectron spectroscopy (XPS), and solid-state nuclear magnetic resonance (solid-NMR). The analysis revealed that GVL- and DMSO-based electrodes exhibited performance levels comparable to NMP, confirming their feasibility as alternative solvents in the electrode fabrication process. These findings suggest that GVL and DMSO have the potential for real-world application in the LIB industry, thus contributing to sustainable battery production.