What is the most advanced battery

Foundation stone laid for advanced dual-ion batteries

Binary electrolyte mixture increases capacity

Inexpensive and without toxic materials: dual-ion batteries are considered to be very promising for sustainable energy storage. In an international cooperation project with the participation of the MEET Battery Research Center of the Westphalian Wilhelms University Münster, new knowledge was gained for a better fundamental understanding of the intercalation mechanisms and the structures of the resulting graphite intercalation compounds (GICs). They serve as a basis for improving the energy density and cycle performance of positive graphite electrodes in dual-ion and dual-graphite batteries and thus represent a further step towards the possible commercialization of the future-oriented technology.

The electrolyte in focus

In order to better understand the properties of the anion storage, the international research team examined binary, highly concentrated mixed electrolytes based on two different lithium salts. The electrolyte acts as an active material in the dual-ion batteries: Instead of just one type of ion - the lithium-ion - the electrolyte anions are also involved in energy storage in the dual-ion battery. Dr. Tobias Placke, Head of Materials at the MEET Battery Research Center, explains: "Despite its important role, the mechanism of anion storage and the structures of the resulting GICs are not yet sufficiently understood." The researchers succeeded in using in-situ X-ray diffraction studies in combination with ex-situ 19F -Magic-Angle-Spinning (MAS) nuclear magnetic resonance (NMR) measurements to identify GICs in different charge states. They also found that the binary electrolyte mixture compared to the single salt electrolytes shows a significantly increased capacity retention after 100 cycles and improved intercalation kinetics - and thus improved conductivity. "On the basis of this knowledge, the electrolyte for dual-ion batteries can be further optimized," says Dr. Tobias Placke.

Detailed results of the study were published in the "Journal of The Electrochemical Society". The authors are MEET scientists Lukas Haneke, Dr. Andreas Heckmann and Dr. Tobias Placke and Prof. Dr. Martin Winter, MEET Battery Research Center and Helmholtz Institute Münster, Joop Enno Frerichs and Prof. Dr. Michael Ryan Hansen from the Institute for Physical Chemistry at the Westfälische Wilhelms-Universität Münster, Prof. Michael M. Lerner from the Department of Chemistry, Oregon State University (Oregon, USA), Prof. Taner Akbay from the Department of Materials Science and Nanotechnology Engineering, Yeditepe University (Istanbul, Turkey), and Prof. Tatsumi Ishihara from the Department of Applied Chemistry, Faculty of Engineering, Kyushu University (Fukuoka, Japan). The study is embedded in the international cooperation project "Dual-Carb", which was funded by the Federal Ministry of Education and Research.

Research on "excellent" technology

The potential of dual-ion batteries as a future technology is also reflected in the ranking of the “Top Ten Emerging Technologies in Chemistry 2020”. The International Union of Pure and Applied Chemistry (IUPAC) selected the dual-ion battery among the ten most promising technologies that are currently capable of solving “major global problems”. MEET holds important basic patents on this technology and has also coined the term “dual-ion battery”.

The International Union of Pure and Applied Chemistry was founded in 1919 by chemists from industry and science. She is the world authority on chemical nomenclature and terminology, including the naming of new elements in the periodic table. IUPAC has 1623 organizations in 75 countries. Chemists from the Westfälische Wilhelms-Universität Münster are also represented here.