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Institute of Energy and Climate Research

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Solid Oxide Fuel and Electrolysis Cells

Solid oxide fuel cells (SOFCs)

Our effort concentrate on materials and manufacturing processes for solid oxide fuel and electrolysis cells. Mainly powder technology processes are used. Our expertise lies in the parallel development of suitable materials and microstructures tailored to optimize their long-term performance.

SOFCs (solid oxide fuel cells) convert chemical energy directly into electrical energy. This means that conversion losses as occur in conventional heat-to-power devices can be avoided, and thus high electrical system efficiencies of up to 60 % can be achieved. If the thermal energy is also used, efficiencies of more than 80 % are possible. SOFCs function at operating temperatures of 650–950 °C and for this require both the electrochemical cell itself and the components close to it, such as interconnects (bipolar plates), sealants, as well as contact and protective materials, to be of specifically adapted high-temperature materials. Forschungszentrum Jülich is developing a special design type for this: a planar, anode-supported SOFC. It has the advantage of lower resistances and relatively simple manufacturing technology and thus permits lower operating temperatures and manufacturing costs – features that will accelerate the market introduction of these devices.

SOFCs various sizesFigure 1 : Anode-supported SOFCs of various sizes

As part of SOFC research, IEK-1 is investigating the cells themselves, and also the contact and protective layers. Research and development starts with the synthesis of suitable materials or the purchase of commercially available materials and their special adaptation: ranging from manufacturing transport media (powders, slips, pastes, suspensions), layers, components, and parts up to and including scaling them in terms of component size, homogeneity, and reproducibility as appropriate for application in a pilot plant. For the manufacturing processes, mostly powder-based methods from metal and ceramic powder processing are applied, such as pressing, tape casting, screen printing, or powder injection. If certain properties are required of the functional layers, thin-film processes (PVD, sputtering) or precursor-based techniques such as the sol-gel process may also be applied (spin or dip coating, inkjet printing). Studies on the degradation of SOFCs and post-test analyses of fuel cell stacks round off the research portfolio.

SOFCs cathode side viewFigure 2a: Anode-supported SOFCs in a Jülich F10 design stack viewed from above, cathode side (stack manufactured by ZEA-1)

SOFCs anode side viewFigure 2b: Anode-supported SOFCs in a Jülich F10 design stack viewed from above, anode side (stack manufactured by ZEA-1)

Recently, SOFC research has expanded to include applications in high-temperature electrolysers to produce hydrogen (SOEC: solid oxide electrolysis cell) and as high-temperature batteries (ROB: rechargeable oxide battery) for the temporary storage of volatile electricity.

Another research and development field is the understanding of sintering layers, bulky components, and layer composites under the influence of temperature, atmosphere, and electric field. For this purpose, the following facilities are at our disposal: SPS (spark plasma sintering), FAST (field assisted sintering), HIP (hot isostatic pressing), etc.

Production processes

SOFC electrolytes; detail of casting headFigure 3: Micro tape casting of an SOFC electrolyte, detail of the casting head

Screen printing of SOFC electrolyteFigure 4: Screen printing an SOFC electrolyte, detail of the squeegee

Projects: Solid Oxide Fuel and Electrolysis Cells

NeStPEL, Neuartige kostengünstige Stromkollektoren für die PEM-Elektrolyse zur Herstellung von Wasserstoff aus regenerativen Energien „Novel cost-effective current collectors for PEM electrolysis for hydrogen generation from regenerative electricity“, BMWi (Forschungszentrum Jülich IEK-3, IEK-1, Siemens, GKN Sinter Metals Filter GmbH), 05/2015 - 04/2018

KerSOLife100, All-Ceramic SOFC-Concept for Cost-Effective µ-CHPs: Long-Term Behaviour, Degradation Mechanisms, Material and Processing Optimization, BMWi (Forschungszentrum Jülich IEK-1, IEK-3, Robert Bosch GmbH, RJL Micro & Analytic GmbH, KIT, Hochschule Karlsruhe, Hochschule Aalen); 09/2016-06/2019

SynSOFC 2, The coupling of a biomass gasifier with a solid oxide fuel cell (SOFC) to produce electricity from biomass is being studied within the framework of a joint project of Forschungszentrum Jülich and TU München, funded by the Deutsche Forschungsgemeinschaft (DFG). The objective of this dissertation is the development of new material combination for the fuel electrode with an improved tolerance against contaminants in the fuel gas. The material systems under investigation include cermets based on Nickel and Gadolinium-doped ceria (GDC) as well as innovative ceramic materials that exsolve nano-scaled catalyst particles during operation. The materials and components developed at IEK-1 will be tested at TU München using synthetic Syngas with controlled amounts of contaminants, in order to investigate the interaction of each molecule with the material.