Sunfire commercially distributes products for various markets (SOFC, SOEC and Co-SOEC) with its stack and system technology. To achieve an ideal tradeoff between cost, performance, and degradation for its customers, Sunfire’s stack design is continuously being improved. In this publication, latest results that resulted in a decrease of the combined life cycle costs (€ kW-1 h-1) of approx. 40% and cost projections for large scale production will be presented. Furthermore, recent changes in automation and industrial scale-up that lead to a current annual production volume of >10MW and next steps to further increase this value will be shown. Last but not least, updates on the recent development for Sunfire’s products Home, Remote and Hylink/Synlink will be given.

Metallic interconnects represent the main component of a solid oxide fuel cell (SOFC) stack in terms of weight and volume. They are typically made of ferritic stainless steel (FSS) coated on the air side. At the stack operating conditions, the interconnect is exposed to a dual atmosphere: air at the cathode side; fuel (a hydrogen-rich mixture) at the anode side. The stacks considered in this study were field operated in reformed natural gas for 5000, 9000 and 20,000 h respectively. The analyzed interconnects are made from CROFER22APU and coated on the air side with Co-Mn base spinel. One interconnect has been studied for each stack by sampling and preparing cross section the inlet and outlet positions. The samples were characterized by SEM-EDXS in order to investigate the evolution of the interconnect at the air side. The interaction between the metal substrate and the coating is investigated highlighting the formation of chromia based thermal grown oxide (at the FSS/coating interface) and the solid-state diffusion of Cr and Fe from the metal into the coating. The microstructural features evolving as a function of time are also quantified.

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In the past years, sunfire has increased its product portfolio and production depth. Four product classes (single stacks and stack modules for SOFC and SOEC) are tackling several markets (offgrid, on-grid, mobile). A ceramic center and a new production facility were inaugurated. The R&D activities are strongly driven by market requirements. With the new SOC stack electrolysis operation is introduced aside fuel cell operation. Furthermore, an increase in power density and a reduction of cost was achieved under the constraint of using standard industrial materials. Latest results of SOC single stack testing like I-V curves and reversible operation will be presented. The engineering and testing of stack modules in the power range >25 kW will be also shown. Company PortraitStarting to produce fuel cell stacks by 2006, sunfire established a vast experience of the SOFC technology. Besides the continuous economic growth, the last years led to a focus shift onto a new field of application, combining SOFC and SOEC into a universal -so called SOC stack which is capable of both transforming chemical energy into electrical energy and vice versa. Market demand shows, that besides the "classic" SOFC fields of application like remote and mobile power generation e.g. in automotive, ships or at pipeline control stations, the SOC addresses the need for electricity storage and fluctuation buffering which came up with the fast rise of sustainable energy production in industrial countries. Acting as an electrolyser when there is an oversupply of wind-or solar power, the SOC turns electrical energy into chemically bound energy in the form of H 2 , which can be stored in almost unlimited amounts. In the moment the electricity demand exceeds the supply, SOC is turned from electrolyser to fuel cell mode and converts the gas bound energy back to electricity. Recently there are plenty of requests of multinational companies that want to include SOC products into their portfolio. Hereby, sunfire can act as a vendor of stacks, stack modules with already integrated gas supply or whole systems in the power range of one to several hundred kW. Recently, a company-owned pilot plant for a power-to-liquid process is put into operation. With the use of SOEC technology, the plant produces liquid fuels and other valuable products like highly purified and customized waxes for chemical industry.Besides the focus on R&D in both stack and integration topics, the development and optimization of production processes play a role with increasing importance for the company. As the stack production will exceed the number of 1000 stacks/a. in 2015, there is a tremendous potential for production automation, which will subsequently lead to 10.1149/06801.0125ecst ©The Electrochemical Society ECS Transactions, 68 (1) 125-129 (2015) 125 ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 155.69.4.4 Downloaded on 2015-08-23 to IP

The penetration of fuel cells and electrolyzers in energy systems calls for their scale-up to the gigawatt (GW) level. High temperature solid oxide cells (SOC) offer unrivaled efficiencies in both electrolysis and fuel cell operation. However, they are made of ceramics and are brittle by nature. Consequently, a high mechanical strength to avoid failure during stacking is essential to achieve a high manufacturing yield. Here, we show that without changing the materials of the state-of-the-art cells, thin and dense ceria interlayers enable comparable power densities and durability in fuel cell operation. The sole tuning of the morphology and processing of the interlayers reduce the residual stress in the cell significantly which increases its mechanical strength by up to 78%. These results promise performance gains of similar magnitude by enabling a substantial decrease of the electrolyte thickness while maintaining robustness. This stress engineering approach presents a way to increase the volumetric power density and material efficiency of SOC systems.

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In order to prevent detrimental reaction during manufacturing and enable the use of high performing La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) cathode in electrolyte supported solid oxide cells, Ce0.8Gd0.2O2-δ (GDC) barrier layer is implemented between the cathode and the electrolyte. It is of great interest to manufacture thin and dense GDC layer at low temperature to avoid unfavorable reactions. GDC layers deposited through Electron-Beam Physical Vapor Deposition (EB-PVD) were investigated to address this challenge. Dense GDC barrier layers of different thickness were deposited onto yttria-stabilized zirconia (YSZ) electrolyte. Samples coated with GDC thin-film, with and without LSCF cathode, were thermally treated to simulate further cell and stack processing steps. XRD and SEM were applied to evaluate the phase composition, thermomechanical stability, morphology and microstructural changes. It is found that the 0.5 µm GDC layer remains crack-free and adherent to the substrate after the simulated thermal cycles.