Materials and Components

Department

Ceramic Energy Converters

Group

High-temperature fuel cells (SOFC) and high-temperature electrolysis cells (SOEC) have had a long history at Fraunhofer IKTS. The Ceramic Energy Converters workgroup did research on SOFCs (solid oxide fuel cells) as early as the 1990s and in doing so has gathered extensive know-how on the design and production of planar fuel cell stacks. The range of competences covers glass solder development, tape technology, as well as the design and processing of interconnectors, cell development and contacting on the gas and air sides, joining techniques, simulation and the initializing of SOFC stacks.

SOFC stack development

High-temperature fuel cell stacks are a core component in any SOFC system. Their performance and reliability, as well as the reproducible manufacturing at moderate cost, are prerequisites for fuel cell systems finding wider use on the market.

Researchers of Fraunhofer IKTS support users in the development of stack designs that are tailored to the client’s requirements. This includes the construction of prototypes as well as the testing of system performance using standardized and adapted characterization techniques. For instance, Fraunhofer IKTS develops with its partners fuel cell stacks for use in decentralized energy supply systems – from micro-CHP units to systems with more than 20 kW power. Furthermore, the research institution configures for its clients automatable manufacturing processes for the cost-efficient manufacturing of fuel cells.

© Fraunhofer IKTS

30-level MK352 stack made of CFY interconnectors: The heart of fuel cell, electrolysis and alternating power conversion systems.

© Fraunhofer IKTS

Assembly of a CFY stack.

© Fraunhofer IKTS

Different areas of application for MK35x CFY stacks. Use in fuel cell (SOFC), electrolysis (SOEC) and alternating (rSOC) operation.

High-temperature electrolysis

In the early 2000s, the researchers transferred their experience and the trends from fuel cell research to the field of high-temperature electrolysis (SOEC), which represents the reverse function of the SOFC operation. In the electrolytic mode, a voltage is applied and water vapor, carbon dioxide or a mixture of both gases (co-electrolysis) are reduced. The excess electric power results in a fuel gas, which can be stored and converted back into electricity.

However, the fuel gas can also be used as syngas in the Fischer-Tropsch synthesis, for the sustainable production of chemical products. A few research projects at Fraunhofer IKTS are currently trying to refine this process.

rSOC: Generator of electricity and energy storage in one single system

The latest developments are aimed at integrating the generation of electricity and its storage into one single system. To achieve this, the Ceramic Energy Converters group has developed what are called ‘reversible solid oxide cells’, or rSOCs. These reversible high-temperature solid oxide cells combine the advantages of the fuel cell with those of the electrolytic cell. This creates an efficient, reversible energy conversion system, which generates electricity, stores excess electric energy and feeds it back into the cycle if needed – or produces chemical substances in a sustainable way in an additional recycling route.

Quality assurance for SOFC, SOEC and rSOC

For rSOCs as well as for fuel cells and electrolytic cells, activities focus on keeping costs and degradation rates down. This includes individual components in the same way as the stacks and complex energy systems. Fraunhofer IKTS is part of a global network of partners and is setting standards for the testing of components, stacks and stack modules with regard to long-term testing, cyclization and analyses of accelerated aging processes.

© Fraunhofer IKTS

Test rigs for SOFC fuel cell systems.

© Fraunhofer IKTS

Solid oxide fuel cell (SOFC) stack modules.

© Fraunhofer IKTS

Sealed 30-cell SOFC stack.

Services offered for fuel cells and electrolysis systems

 

  • Testing of stack components for fuel cells and electrolysis cells (SOFC/SOEC/rSOC) under real operating conditions
  • Testing of SOFC/SOFC/rSOC stacks of different sizes
  • Stack and stack module development for use in SOFC/SOEC/rSOC systems, through to prototype manufacturing
  • Analysis of degradation processes in SOFC/SOEC/rSOC stacks and clarification of the degradation mechanisms
  • Marketing of SOFC/SOEC/rSOC stacks and fuel cells/electrolysis modules for various applications