Comparison of Alternative Solvents for Cathode Production of Lithium Ion Batteries
The solvent N-methyl-2-pyrrolidone (NMP) is currently required to produce positive electrodes (cathodes) for lithium ion batteries. It is characterized by good wetting properties, a high boiling point, allowing controlled evaporation during electrode drying, and an adequate dissolution of the conventionally used binder polyvinylidene difluoride (PVDF). However, it is hazardous to health and, if it is not recovered after drying, harmful to the environment. With the aim of replacing NMP as a solvent without compromising the performance of the battery cells, a team from MEET Battery Research Center at the University of Münster has now compared potential alternatives for cathode production.
Innovative Solvent Can Be Applied Directly in Production
The team investigated among others the influence of the solvents dihydrolevoglucosenone (cyrene) and dimethyl sulfoxide (DMSO). “Cyrene did not achieve convincing results in terms of cell performance. In contrast, DMSO delivered comparable results to NMP,” explains MEET scientist Candeniz Gercek. Another advantage of DMSO is that the solvent can be integrated into existing battery production lines without major adjustments. “Replacing NMP with DMSO is an important step towards a more sustainable electrode production process,” says Gercek.
In addition to the cost- and energy-intensive drying process, NMP recovery leads to substantially enhanced energy consumption in battery production. Dr Markus Börner, Head of the Research Division Cell System at MEET Battery Research Center, adds: “It is of crucial importance, both ecologically and economically, to replace NMP. With our results, we are making a decisive contribution to achieve this.”
Detailed Results Online Available
The entire study has been published by the authors Candeniz Gercek, Johanna Kauling, Dr Bastian Heidrich, und Dr Markus Börner, MEET Battery Research Center, as well as Prof. Dr Martin Winter, MEET Battery Research Center and Helmholtz Institute Münster, in the journal “ACS Applied Energy Materials”.