An environmentally friendly dry electrode process has been developed that increases the energy density of lithium-ion batteries while not using hazardous solvents. It is expected that the energy use of electric vehicles and various electronic devices will become more sustainable.

Professor Kyung-Min Jeong's team from the Department of Energy and Chemical Engineering at UNIST (Ulsan National Institute of Science and Technology) announced on the 25th that they have newly developed a dry electrode unit process and a semi-finished product evaluation method for lithium-ion batteries. This dry process, which does not use harmful solvents, helps improve battery performance while also protecting the environment.

By defining the detailed steps of the dry process and analyzing the impact of each step on battery performance, we have moved one step closer to commercialization. This is an advancement over the limitations of previous research that was limited to performance evaluation.

Lithium ion battery electrodes are traditionally manufactured using a wet process. However, when thick electrodes are used, the uneven distribution of binders and conductive materials causes performance degradation problems. On the other hand, the dry electrode process can produce uniform electrodes without using organic solvents, but it remains in laboratory-level research that is difficult to commercialize.

The research team increased the possibility of commercialization by introducing a solvent-free dry process based on polytetrafluoroethylene (PTFE) binder. The process is divided into granule formation, film formation, rolling, and lamination stages. The physical, electrical, and electrochemical properties of the semi-finished products manufactured at each stage were evaluated to find the optimal process conditions.

In particular, it was discovered for the first time that using a binder with a high extrusion ratio of PTFE can produce a high-strength electrode film even with low energy, and that the microstructure of the electrode is improved, thereby enhancing the output characteristics.

In lithium ion batteries, binders play an important role in connecting active materials and electrons. In commercial wet electrode processes, the performance of the process and electrodes varies greatly depending on the type and content of the binder. In dry electrodes, we also identified how the output characteristics of each process and the final electrode change depending on the type and content of the PTFE binder.

Professor Jeong Gyeong-min emphasized, “The process of making electrodes one by one by hand had the problem of making mass production difficult and maintaining consistent quality,” and “This research will contribute to commercialization as it goes beyond the laboratory scale and is segmented into unit processes.”

First author, researcher Hye-Seong Oh, said, “In this study, we found a clue to improving the output characteristics of the electrode through evaluation according to the type and content of PTFE,” and “Through follow-up research, we would like to further improve the output characteristics of thick electrodes by applying various materials.”

This study was published in the Chemical Engineering Journal, a world-renowned chemical engineering academic journal, and was conducted through the 'Development of Material/Process Innovation Convergence Solutions for Carbon-Neutral High-Energy Density Batteries' project, a creative convergence research project supported by the National Research Council of Science and Technology (NST).

Meanwhile, the Korea Institute of Energy Research and Hanwha Corporation, which are conducting joint research, plan to produce specialized dry electrode manufacturing equipment and conduct verification tests starting in the second half of this year.