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Fluoride batteries: A promising concept for the future

From research conducted at the Karlsruhe Institute of Technology
Zusammenbau Testzelle

Eine Wissenschaftlerin beim Zusammenbau einer Testzelle in einer Handschuhbox unter Schutzgasatmosphäre, die ungewünschte Reaktionen verhindert. Foto: KITRead more


Unter kontrollierten Temperaturbedingungen werden die einzelnen Batteriezellen getestet. Foto: KIT Photo/Graphic: www.kit.edu.

Lithium-ion batteries are currently the most powerful battery systems on the market, but their storage capacity cannot be increased much further.

Nevertheless, many applications – especially in vehicles and fixed and mobile devices – require batteries that can store more energy and are considerably more compact. An entirely new battery concept has been developed by KIT scientists working under Dr. Maximilian Fichtner at the Institute of Nanotechnology. The group is using new composite electrodes in which the cathode consists primarily of a metal fluoride compound and the main component of the anode is a metal. Today’s lithium-ion batteries can only store up to one electron per heavy transition metal atom of the electrode, but with the help of fluoride ions, storage capacity can be increased to up to three charge carriers. At that point metal fluoride forms on the electrode or, conversely, fluoride ions are released and the metal is reconstituted. “Using this process we can theoretically achieve energy densities up to 50 percent higher than those of the lithium-ion battery that is currently regarded as the upper limit,” says Fichtner. Although the principle works, researchers still have a great deal of work to do on the details: they need to improve the battery system’s initial capacity, operating life and cycle stability. In addition, the solid electrolyte, which enables the charge to be transferred between electrodes, works only at elevated operating temperatures. “We’re now developing new solid and liquid electrolytes that will make it possible to use the battery at room temperature,” says Fichtner.


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