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 sodium-based batteries. Cells and battery modules are characterized and simulated thermally and electrically, to tailor them for specific applications. Other topics of interest are safety and abuse investigations 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 our abuse test laboratories we can conduct thermal, mechanical and electrical safety tests on Li-ion cells and on modules with an energy content of up to 2 kWh. In the field of redox-flow batteries we are investigating 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 work 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. We address materials for oxygen evolution / (OER) catalysts for PEM electrolysis but also 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, our focus is on method development for the investigation of degradation processes, in particular carbon and ionomer corrosion, using online mass spectrometry. In addition, we support the development of test methods for fuel cell components, for example the characterization of bipolar plates and the GDL. 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 the control system.
Hydrogen is used, among other things, as a fuel to power fuel cells in mobile and stationary applications. We ensure the necessary safety, examine the hydrogen in the respective system and investigate various operating conditions - right up to the worst-case scenario. For example, we calculate possible leaks and faults, use theoretical results to direct hydrogen specifically into cavities, and test the implementation at our test site, which is designed for up to three kilograms of TNT equivalent. In addition, we deal with 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 the fuel cells for reconversion, the use of the waste heat from the fuel cells, and demand-oriented distribution via local heating networks. We set up the system control and perform stress tests by simulating possible failure cases.
One way to use electric energy efficiently is to generate chemical products. We are working on the development of electrochemical reactors, including electrocatalysts and electrodes, their integration into a complete process, and subsequent process steps. A current example is the electrochemical extraction of hydrogen peroxide by the partial reduction of atmospheric oxygen, combined with its use in a selective oxidation.
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 chemical storage, Fraunhofer ICT is concerned with hydrogen as an energetic material and platform chemical. A particular area of expertise is safety assessment and the design of systems, pilot plants and processes.
Important research areas are the handling and especially the storage and transport of hydrogen, the development and performance of specific safety tests and the evaluation, concept and design of hydrogen storage systems. The equipment available at our Application Center for Stationary Energy Storage Devices enables the characterization and development of a wide spectrum of materials, through to the behavior of a storage device in an electric grid with renewable energy sources.