A ceramic film produced by powder aerosol deposition on a porous gas-permeable electrode. Image: Jörg Exner.
Rechargeable batteries with a solid electrolyte promise increased safety compared to cells with liquid electrolytes. At the same time, it seems possible to significantly increase their energy density. The greatest challenge for industrial production of solid-state batteries with high energy density lies in producing cathodes and electrolytes that are made up of fine ceramic layers. In recent years, the powder aerosol deposition (PAD) method has established itself as an efficient method for producing such layers. With this spray method, dense ceramic layers can be applied to very different types of materials, such as steel, glass, silicon, or plastic. Just how high the resulting layers are in detail can be determined exactly in advance. As a rule, they are between 0.5 and 50 micrometres thick. For comparison, a human hair measures about 60 micrometres. The coating can be applied at room temperature, is inexpensive, and consumes little energy. Consequently, PAD can be considered a sustainable method, and in this respect is contributing to the development of the "green battery".
"Solid State Batteries - FestBatt" is already the fifth cluster of competence of the "Research Factory Battery" network in which the University of Bayreuth is involved with an own project. Overall management of this project with the acronym "AdBatt" ("Aerosol Deposition for the Production of Batteries with Graded Cathode") is the responsibility of Prof. Dr.-Ing. Ralf Moos, Department of Functional Materials at the University of Bayreuth. Together with his research team, he has driven the further development and optimisation of PAD in recent years. "PAD is a powerful and at the same time environmentally friendly process. We now wish to use it together with our partners in Karlsruhe and Saarbrücken to achieve a volumetric energy density of 1,150 Wh/l in the field of all solid-state batteries," says the Bayreuth engineering scientist. An important aspect of the research work is the development of a process that makes it possible to produce cathodes with variable proportions of different material types. These include the active material of the cathodes, the solid electrolyte powder, and electronically conductive additives.
At the same time, the Electrical Energy Systems research group at the University of Bayreuth, headed by Prof. Dr.-Ing. Michael Danzer, is also participating in the new project. The research work focuses on the electrochemical behaviour of graded electrodes with solid electrolyte, but also on the general conditions for safe battery operation. For this purpose, suitable operating values and limits must be defined for the parameters of temperature, pressure, and current density. "Of central importance to our research work is precise modelling and efficient simulation of electrochemical processes, especially with regard to the interactions between electrolyte, electrode, and full cell. On this basis, we will be able to gradually optimize the design of the graded solid-state batteries we are aiming for," says Danzer, who is also Head of the Bavarian Centre for Battery Technology (BayBatt) at the University of Bayreuth.
Contact for scientific information:
Dr. Julia Menzel
Coordinator
Bavarian Centre for Battery Technology (BayBatt)
University of Bayreuth
Phone: +49 (0)921 55 5877
E-mail: julia.menzel@uni-bayreuth.de
