SulForFlight

Compared to lithium-ion batteries, lithium-sulfur batteries can store about twice as much energy  for the same weight. This property has particular relevance for aerospace applications. Combined with the low cost and high material availability of sulfur, this opens up a range of use cases for resource-efficient mobility. Nevertheless, no commercial lithium-sulfur batteries are available yet. Long development times and specific technological hurdles are the reasons for the currently still relatively low degree of maturity of this system.

The use of lithium-sulfur batteries in aerospace applications places special demands on the energy density, operating conditions, service life and safety of the batteries. A wide range of battery performance characteristics can be covered through specific design of the processes, electrodes and cell design, as well as through material selection. By combining experimental and virtual methods of battery research, development time and development costs can be reduced and energy storage systems tailored to the application scenarios can be developed.

The BMBF-funded SulForFlight project (FKZ 03XP0491) is taking a holistic approach to researching the determining parameters and properties in the processing, operation and aging of the cells, starting with the manufacture of the electrodes and ending with the final safety tests. The long-standing competencies of the consortium partners in the areas of processing (iPAT of TU Braunschweig, Fraunhofer IWS), experimental characterization (Fraunhofer IWS, DLR-TT) and modeling (DLR-TT) are combined and brought together to optimize the battery cells and their production.

Optimized process chains for the continuous and scalable production of electrodes and cells with targeted structural properties and performance characteristics are determined for two material concepts (carbon-based composite electrodes and electrodes with covalently bonded sulfur (SPAN)). Data will be collected via inline and offline measurement techniques for quality inspection as well as characterization of the intermediate and final products.

Various operando measurement methods on laboratory and pouch cells are used for experimental characterization. The electrochemical characterization in combination with aging and safety tests allows a detailed understanding of the relevant physicochemical processes and also serves to evaluate the cells.

The information finally flows into the modeling of the cells. Material, structural and electrochemical properties of the lithium-sulfur cells are mapped in a digital twin of the real system. The parameterization of the digital twin and thus the quality of the predictions are supported by machine learning approaches. The model is used to optimize electrode and cell properties and to upscale to large-scale cells. Insights gained through simulations are fed back into processing and electrode manufacturing, thus forming an iteratively optimizing development cycle.

The processes, methods and workflows developed in SulForFlight are intended to further advance the development of lithium-sulfur batteries in terms of energy density, costs, reliability and service life. In the future, this technology will be used to realize energy storage systems for alternative propulsion concepts in the aerospace industry and to transfer them to new fields of application.

Contact:

Robin Moschner
robin.moschner(at)tu-braunschweig.de