Technische Universität München
Neutrons show how lithium-ion batteries can be filled faster
TECHNICAL UNIVERSITY OF MUNICH
Corporate Communications Center
phone: +49 89 289 10510 - e-mail: presse@tum.de - web: www.tum.de
This text on the web: https://www.tum.de/nc/en/about-tum/news/press-releases/detail/article/34503/
High resolution images: https://mediatum.ub.tum.de/1435982
Video: https://youtu.be/-vv0mKwYjO4
NEWS RELEASE
Filling lithium-ion cells faster
Neutrons pave the way to accelerated production of lithium-ion cells
Developers from Bosch and scientists at the Technical University of Munich (TUM) are using neutrons to analyze the filling of lithium ion batteries for hybrid cars with electrolytes. Their experiments show that electrodes are wetted twice as fast in a vacuum as under normal pressure.
One of the most critical and time-consuming processes in battery production is the filling of lithium cells with electrolyte fluid following the placement the of electrodes in a battery cell. While the actual filling process takes only a few seconds, battery manufacturers often wait several hours to ensure the liquid is fully absorbed into the pores of the electrode stack.
The fact that neutrons are hardly absorbed by the metal battery housing makes them ideal for analyzing batteries. That is why Bosch employees, in collaboration with scientists from the TU Munich and the University of Erlangen-Nuremberg, investigated the filling process at the neutron imaging and tomography facility ANTARES of the research neutron source FRM II.
Faster in a vacuum
Manufacturers of lithium cells often fill the empty cells in a vacuum. The process is monitored indirectly using resistance measurements. "To make sure that all the pores of the electrodes are filled with the electrolyte, manufacturers build in large safety margins," says Bosch developer Dr. Wolfgang Weydanz. "That costs time and money."
In the light of the neutrons, the scientists recognized that in a vacuum the electrodes were wetted completely in just over 50 minutes. Under normal pressure, this takes around 100 minutes. The liquid spreads evenly in the battery cell from all four sides, from the outside in.
In addition, the electrodes absorb ten percent less electrolyte under normal pressure. The culprit is gases that hinder the wetting process, as the scientists were able to demonstrate for the first time using the neutrons.
Publication:
Visualization of electrolyte filling process and influence of vacuum during filling for hard case prismatic lithium ion cells by neutron imaging to optimize the production process
W.J. Weydanz, H. Reisenweber, A. Gottschalk, M. Schulz, T. Knoche, G. Reinhart, M. Masuch, J. Franke, R. Gilles
Journal of Power Sources, Volume 380, 15 March 2018, Pages 126-134, DOI: 10.1016/j.jpowsour.2018.01.081
Link: https://www.sciencedirect.com/science/article/pii/S0378775318300818
High resolution images:
https://mediatum.ub.tum.de/1435982
Video of the filling process:
Video: https://youtu.be/-vv0mKwYjO4
Filling of a lithium-ion cell (left: normal pressure, right: vacuum): The wetting of the electrode (dark area) proceeds evenly from all sides. After approx. 50 min., the electrode filled under vacuum is completely wetted. (Image: Wolfgang Weydanz/Ralph Gilles / Bosch/TUM)
Contact:
Dr. Ralph Gilles
Technical University Munich
Research-Neutronsource Heinz Maier-Leibnitz (FRM II)
Lichtenbergstr. 1, 85748 Garching, Germany
Phone: +49 89 289 14665 - e-mail: Ralph.Gilles@frm2.tum.de
http://www.mlz-garching.de/antares
The Technical University of Munich (TUM) is one of Europe's leading research universities, with around 550 professors, 41,000 students, and 10,000 academic and non-academic staff. Its focus areas are the engineering sciences, natural sciences, life sciences and medicine, combined with economic and social sciences. TUM acts as an entrepreneurial university that promotes talents and creates value for society. In that it profits from having strong partners in science and industry. It is represented worldwide with the TUM Asia campus in Singapore as well as offices in Beijing, Brussels, Cairo, Mumbai, San Francisco, and São Paulo. Nobel Prize winners and inventors such as Rudolf Diesel, Carl von Linde, and Rudolf Mößbauer have done research at TUM. In 2006 and 2012 it won recognition as a German "Excellence University." In international rankings, TUM regularly places among the best universities in Germany. www.tum.de