We develop new, efficient options for electrical energy storage, and investigate systems that are already available on the market. Our emphasis is on lithium-ion batteries, all-solid-state batteries, redox-flow batteries and so-called post-lithium-ion systems, such as lithium-sulfur or sodiumbased batteries. Cells and battery modules are characterized and simulated thermally and electrically, to tailor them for specific applications. We also carry out safety and abuse tests with accompanying gas analysis, post-mortem investigations on cells and battery modules, and the development and validation of safety concepts for operation, transport and storage. In the field of redox-flow batteries we investigate various cost-effective and sustainable storage materials, and are working to reduce the cost of the overall system, in particular the stack structure and materials.
Our research in the field of converters is divided into three main topics: material development, testing and system development. As regards material development, we focus on catalyst systems for water electrolysis, materials for oxygen evolution/(OER) catalysts for PEM electrolysis and supported catalysts and noble-metal-free OER catalysts for AEM electrolysis, starting from MOF precursors. We are also developing electrocatalysts for use in HT-PEMFCs and DMFCs. In fuel cell testing, we develop methods to investigate degradation processes, in particular carbon and ionomer corrosion, using online mass spectrometry. We optimize the operation of commercial fuel cell stacks for special applications in the military and civil sectors and develop the systems required for this, including the selection of suitable peripheral components and control systems.
We continue to research hydrogen as a fuel to power fuel cells in mobile and stationary applications. The main topic here is hydrogen safety in the respective system. We investigate various operating states up to the worst-case scenario. For this purpose we calculate possible leakages and errors, and conduct trials on our test site - which is designed for up to three kilograms of TNT equivalent - to validate the conversion
of hydrogen. In addition, we examine issues relating to the safety distance in the refueling area and the pressure protection of fuel tanks. For energy supply in residential quarters with regeneratively produced hydrogen, we design the overall layout of the system including fuel cells for reconversion, the use of waste heat from the fuel cells, and demand-oriented distribution via local heating networks.
Thermal storage devices based on phase-change materials (PCMs) or zeolites are developed and characterized. This involves basic physical and chemical characterization, including the modeling and characterization of adsorption and desorption phenomena using thermoanalytical methods. The design, construction and testing of sorption storage and sorption cooling systems, heat reservoirs based on phase-change materials, and hybrid components combining thermal mass and insulation, are strongly market-oriented and complement our fundamental research activities.
In the field of electric drive train concepts, we research and develop electric engines and transmission systems for battery electric vehicles. We focus on technologies with a high weight-specific power density and high efficiency. In the field of traction battery system development, our research centers on safe, lightweight solutions with integrated functions, which meet future demands for high energy and power densities and safety requirements during fast charging and discharging. In the area of combustion engine concepts, we aim to develop technical solutions in the entire drive train for mobile applications. We research and develop combustion engines both as the sole drive unit and in combination with an electric engine, as a hybrid drive system. We provide design and simulation support for all developments relating to drive systems, and validate them through experimental trials on our test stands.