Compared to lithium-ion batteries, lithium-sulphur batteries can store about twice the energy for the same weight. This property makes them particularly interesting for aerospace applications. The low costs and high material availability of sulphur are also advantageous. Nevertheless, no commercial products are available yet. In order to make the system usable for mobility, Technische Universität Braunschweig is researching sulphur-based energy storage systems together with partners from industry and research.

The application of lithium-sulphur batteries in aerospace places particularly high demands on battery properties – such as energy density, operating conditions, service life and safety. By specifically designing the processes, the electrodes and the cell design as well as by selecting the materials, the battery performance can be adapted accordingly. By combining experimental and virtual methods, development time and development costs are to be reduced.

Holistic approach

In the research project “SulForFlight”, the parameters and properties in the processing, operation and ageing of the cells are being researched in a holistic approach. The long-standing competences of the consortium partners from the areas of processing (TU Braunschweig, Fraunhofer IWS), experimental characterisation (Fraunhofer, DLR) and modelling (DLR) are combined.

In this project, TU Braunschweig is focusing on process development for the production of sulphur-based batteries and the influences that different process parameters can have on the properties of these batteries. For this purpose, analytics are used during the process, which makes it possible to establish correlations between the manufacturing process and the properties of the intermediate products as well as the later cell.

Next generation energy storage – the advantages

Batteries based on lithium and sulphur are considered the next generation of energy storage. They can store more energy with less weight, so they have a particularly high energy density; the components sulphur and carbon are inexpensive to produce and readily available in large quantities. The goal for the future is, among other things, to significantly increase the range of electric vehicles with this type of battery.

Specific hurdles

However, in order to be able to offer the lithium-sulphur battery as an alternative to conventional lithium-ion batteries, some specific hurdles still have to be overcome. For example, lithium is highly reactive and sulphur tends to form soluble intermediates during operation, which lead to unwanted side reactions that reduce battery life. Other critical factors are the low number of cycles, performance in terms of fast charging and resistance to high temperatures and frost.

Project data:

The project “SulForFlight” (FKZ 03XP0491) is funded by the Federal Ministry of Education and Research (BMBF) with a total of 2.8 million euros (duration 01.09.2022 to 31.08.2025). Project partners are the German Aerospace Center (Institute of Engineering Thermodynamics, DLR-TT), the Fraunhofer Gesellschaft (Institute for Material and Beam Technology, IWS) and Technische Universität Braunschweig (Institute for Particle Technology, iPAT). The industrial advisory board includes: Orion Engineered Carbons, Adeka Corporation, IoLiTec-Ionic Liquids Technologies, Custom Cells Itzehoe, rhd instruments, Airbus.

Source: Press release TU Braunschweig, 01.03.2023