DLR: Better digitization methods for the development of batteries of the future

Battery technologies are now used in all mobile applications on land, air and sea. Conventional lithium-ion batteries based on liquid electrolytes are continuously optimized, but are reaching their physical limits in terms of energy and power stored per volume. Solid-state batteries are a possible alternative.

Since November 2021, the joint project TheoDat in the competence cluster for solid-state batteries “FestBatt” of the Federal Ministry of Education and Research has entered its second funding phase.

Solid State Batteries

Solid-state batteries are a promising concept for the further development of currently available batteries. They are very similar to conventional lithium-ion batteries with liquid electrolyte and differ from them mainly in that a solid electrolyte or “solid electrolyte” for short, usually a ceramic material, is used instead of the liquid electrolyte.

This difference includes several advantages: Solid-state batteries have higher long-term storage capacities, shorter charging times, are lighter and significantly smaller, and offer greater safety because internal short circuits and the resulting induced fires are much easier to avoid than with conventional lithium-ion batteries.

A number of scientific and technological challenges remain to be solved for the commercial success and mass production of solid-state batteries. This is where the FestBatt competence cluster, which is funded by the German Federal Ministry of Education and Research (BMBF) and whose first funding phase involved more than 100 researchers from various research institutions, comes in. FestBatt is coordinated by Prof. Dr. Jürgen Janek from the Center for Materials Research at Justus Liebig University Giessen. The project is part of the umbrella concept “Research Factory Battery” of the Federal Ministry of Education and Research (BMBF), which aims to secure Germany’s technological sovereignty in battery technology.

In a first step, the scientific fundamentals of the material systems of solid electrolytes as core components of solid-state batteries were successfully elaborated. The focus of the second phase is now on the development of cell concepts and entire solid-state battery cells based on these electrolytes and the necessary material and process technology. To this end, the BMBF is continuing its funding of the “FestBatt” competence cluster from November 2021 with a total of around 23 million euros for three years. A total of 17 scientific institutions – including universities, Helmholtz centers and institutes of the Fraunhofer Society and the Max Planck Society – are involved in the competence cluster.

Theory and Data Platform (FB2-TheoDat)

In the second phase, the “FestBatt” competence cluster consists of nine collaborative projects. This also includes the joint project FB2-TheoDat.

In the joint project “Theory and Data”, state-of-the-art simulation and digitization techniques are being developed specifically for solid-state batteries with the aim of developing new cell concepts and significantly accelerating their design, always in close cooperation with the other platforms of the competence cluster.

As partners of the TheoDat platform, the TU Munich, the DLR, the TU Darmstadt, the Karlsruhe Institute of Technology (KIT) and the Westphalian Wilhelms University of Münster are pooling their expertise across the entire simulation chain from the atomistic to the cellular scale. State-of-the-art data science methods will be incorporated to create a virtual research infrastructure for solid-state batteries. The joint project FB2-TheoDat is coordinated by Professor Dr. Arnulf Latz, German Aerospace Center (DLR) e.V..

Digital design tools are essential for accelerating the development of new material- and application-specific battery cell concepts. For this purpose, material-specific mathematical models must be developed. These have the ability to realistically represent in the computer operationally relevant properties of the solid electrolytes used and the processes that occur during the operation of solid-state batteries. This requires close coupling of atomistic material models, complex cell models, and data science approaches. This guarantees the links with the experimental work within the second funding phase of FestBatt.

Physicochemistry-based models are combined with mathematical techniques for analyzing large data sets, such as artificial intelligence techniques. This creates a virtual research environment that can be used to evaluate different cell concepts through simulation and data analysis. In the medium term, this will enable a significant acceleration of development cycles and a reduction in the development costs of solid-state batteries.

To achieve this ambitious goal, novel structurally resolved battery cell models are being developed in collaboration between DLR and TU Munich. They will map processes responsible for both aging and degradation and the achievable power and energy density of batteries. Atomistic simulations from the TU Darmstadt and the University of Münster are used to investigate material-specific issues of the experimental platforms as well as to determine parameters for the cell models. For the parameterization of the cell models, state-of-the-art mathematical techniques are used at the TU Munich, which can extract missing model parameters from heterogeneous experimental data. All information will be collected in a database, which together with additional analysis techniques will be created in the form of a structured data and virtual research infrastructure at KIT.

Based on the successful materials-oriented preliminary work from the first phase of FestBatt, this will provide the tools for simulation-based development of complex cell designs by combining computer simulations and data analysis techniques.