From Karlsruhe Institute of Technology-KIT [Karlsruher Institut für Technologie] (DE): “Record-breaking Lithium-metal Cell”

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From Karlsruhe Institute of Technology-KIT [Karlsruher Institut für Technologie] (DE)

8.25.21

Contact:

Monika Landgraf
Head of Corporate Communications, Chief Press Officer
Phone: +49 721 608-41150
Fax: +49 721 608-43658
presse@kit.edu

Contact for this press release:
Sandra Wiebe
Press Officer
Phone: +49 721 608-41172
sandra.wiebe@kit.edu

Nickel-rich Cathode and Ionic Liquid Electrolyte Enable Extremely High Energy Density and Good Stability – Researchers Report in Joule.

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With a promising combination of cathode and electrolyte, the HIU researchers aim to make a very high energy density possible. Photo: Amadeus Bramsiepe, KIT.

A new type of lithium-metal battery reaches an extremely high energy density of 560 watt-hours per kilogram – based on the total weight of the active materials – with a remarkable stability. Researchers of the Helmholtz Institute Ulm (HIU) of Karlsruhe Institute of Technology (KIT) used a promising combination of cathode and electrolyte: The nickel-rich cathode enables storage of high energy per mass, the ionic liquid electrolyte ensures largely stable capacity over many cycles. This is reported by the scientists in Joule.

Currently, lithium-ion batteries represent the most common solution for mobile power supply. In some applications, however, this technology reaches its limits. This especially holds for electric mobility, where lightweight and compact vehicles with large ranges are desired. Lithium-metal batteries may be an alternative. They are characterized by a high energy density, meaning that they store much energy per mass or volume. Still, stability is a problem, because the electrode materials react with conventional electrolyte systems.

Researchers of Karlsruhe Institute of Technology (KIT) and the Helmholtz Institute Ulm – Helmholtz Association of German Research Centres (DE) for Electrochemical Energy Storage (HIU) have now found a solution. As reported in Joule[above], they use a promising new combination of materials. A cobalt-poor, nickel-rich layered cathode (NCM88) reaches a high energy density. With the usually applied, commercially available organic electrolyte (LP30), however, stability leaves a lot to be desired. Storage capacity decreases with an increasing number of cycles. Professor Stefano Passerini, Director of HIU and Head of the Electrochemistry for Batteries Group, explains the reason: “In the electrolyte LP30, particles crack on the cathode. Inside these cracks, the electrolyte reacts and damages the structure. In addition, a thick mossy lithium-containing layer forms on the anode.” For this reason, the scientists used a non-volatile, poorly-flammable, dual-anion ionic liquid electrolyte (ILE) instead. “With the help of ILE, structural modifications on the nickel-rich cathode can be reduced significantly,” says Dr. Guk-Tae Kim from the Electrochemistry for Batteries Group of HIU.

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The ionic liquid electrolyte ILE (right) largely prevents structural modifications on the nickel-rich NCM88 cathode. After 1000 cycles, battery capacity still reaches 88 percent. (Figure: Fanglin Wu and Dr. Matthias Künzel, KIT/HIU).

Capacity Keeps 88 Percent after 1000 Cycles

The results: The lithium-metal battery with the NCM88 cathode and the ILE electrolyte reaches an energy density of 560 watt-hours per kilogram (Wh/kg) – based on the total weight of the active materials. Its initial storage capacity is 214 milliampere hours per gram (mAh g-1) of the cathode material. After 1000 cycles, 88 percent of the capacity are retained. The average Coulombic efficiency, i.e., the ratio between discharge and charge capacity, is 99.94 percent. As the battery is characterized by a high safety, the researchers have made an important step towards carbon-neutral mobility.

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Mission Statement of KIT

Preamble

Karlsruhe Institute of Technology-KIT [Karlsruher Institut für Technologie] (DE) was established by the merger of the Forschungszentrum Karlsruhe GmbH and the Universität Karlsruhe on October 01, 2009. KIT combines the tasks of a university of the state of Baden-Württemberg with those of a research center of the Helmholtz Association of German Research Centres [Helmholtz-Gemeinschaft Deutscher Forschungszentren] (DE) in the areas of research, teaching, and innovation.

The KIT merger represents the consistent continuation of a long-standing close cooperation of two research and education institutions rich in tradition. The University of Karlsruhe was founded in 1825 as a Polytechnical School and has developed to a modern location of research and education in natural sciences, engineering, economics, social sciences, and the humanities, which is organized in eleven departments. The Karlsruhe Research Center was founded in 1956 as the Nuclear Reactor Construction and Operation Company and has turned into a multidisciplinary large-scale research center of the Helmholtz Association, which conducts research under eleven scientific and engineering programs.

Being “The Research University in the Helmholtz Association”, KIT creates and imparts knowledge for the society and the environment. It is the objective to make significant contributions to the global challenges in the fields of energy, mobility, and information. For this, about 9,300 employees cooperate in a broad range of disciplines in natural sciences, engineering sciences, economics, and the humanities and social sciences. KIT prepares its 24,400 students for responsible tasks in society, industry, and science by offering research-based study programs. Innovation efforts at KIT build a bridge between important scientific findings and their application for the benefit of society, economic prosperity, and the preservation of our natural basis of life. KIT is one of the German universities of excellence.

In 2014/15, KIT concentrated on an overarching strategy process to further develop its corporate strategy. This mission statement as the result of a participative process was the first element to be incorporated in the strategy process.

Mission Statement of KIT

KIT combines the traditions of a renowned technical university and a major large-scale research institution in a very unique way. In research and education, KIT assumes responsibility for contributing to the sustainable solution of the grand challenges that face the society, industry, and the environment. For this purpose, KIT uses its financial and human resources with maximum efficiency. The scientists of KIT communicate the contents and results of their work to society.

Engineering sciences, natural sciences, the humanities, and social sciences make up the scope of subjects covered by KIT. In high interdisciplinary interaction, scientists of these disciplines study topics extending from the fundamentals to application and from the development of new technologies to the reflection of the relationship between man and technology. For this to be accomplished in the best possible way, KIT’s research covers the complete range from fundamental research to close-to-industry, applied research and from small research partnerships to long-term large-scale research projects. Scientific sincerity and the striving for excellence are the basic principles of our activities.

Worldwide exchange of knowledge, large-scale international research projects, numerous global cooperative ventures, and cultural diversity characterize and enrich the life and work at KIT. Academic education at KIT is guided by the principle of research-oriented teaching. Early integration into interdisciplinary research projects and international teams and the possibility of using unique research facilities open up exceptional development perspectives for our students.

The development of viable technologies and their use in industry and the society are the cornerstones of KIT’s activities. KIT supports innovativeness and entrepreneurial culture in various ways. Moreover, KIT supports a culture of creativity, in which employees and students have time and space to develop new ideas.

Cooperation of KIT employees, students, and members is characterized by mutual respect and trust. Achievements of every individual are highly appreciated. Employees and students of KIT are offered equal opportunities irrespective of the person. Family-friendliness is a major objective of KIT as an employer. KIT supports the compatibility of job and family. As a consequence, the leadership culture of KIT is also characterized by respect and cooperation. Personal responsibility and self-motivation of KIT employees and members are fostered by transparent and participative decisions, open communication, and various options for life-long learning.

The structure of KIT is tailored to its objectives in research, education, and innovation. It supports flexible, synergy-based cooperation beyond disciplines, organizations, and hierarchies. Efficient services are rendered to support KIT employees and members in their work.

Young people are our future. Reliable offers and career options excellently support KIT’s young scientists and professionals in their professional and personal development.

About the Helmholtz Institute Ulm

The Helmholtz Institute Ulm [Das Helmholtz-Institut Ulm] – Helmholtz Association of German Research Centres (DE) was established in January 2011 by Karlsruhe Institute of Technology (KIT), Member of the Helmholtz Association, in cooperation with Ulm University. With the DLR German Aerospace Center [Deutsches Zentrum für Luft- und Raumfahrt e.V.](DE) and the The Center for Solar Energy and Hydrogen Research Baden-Württemberg (ZSW), two other renowned institutions are involved in the HIU as associated partners. The international team of about 130 scientists at HIU works on the development of fundamentals of future energy storage systems for stationary and mobile use.