Publications by Stefan Diethelm

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A short overview of recent work on electroceramic materials relevant to methane-fueled SOFC systems is given. Various fuel feed options are considered, such as pure methane, biogas, and the addition of reforming agents. The principle and implementation into SOFC systems of mixed conducting ceramics for oxygen separation is described, as well as their characterisation by electrochemical methods. Ceramic anodes capable of operating with methane-rich fuel injection are presented. The document concludes with el

Power-to-methane technology has been considered as a promising alternative to cope with seasonal storage of renewable energy and the utilization of CO2 captured from various sources, due to the existing infrastructure for massive methane storage and distri ...

In this work, the effect of sulphur poisoning of the Ni-YSZ electrode of an SOEC operated in co-electrolysis mode was investigated. Short-term tests with exposure up to 5 ppmv of SO2 were performed at OCV and under polarization (0.25 A cm−2). The two-stage ...

Lifetime and durability issues connected with Solid Oxide Fuel Cell (SOFC) technology are strongly related to the amount of contaminants that reach the stack. In this study the focus is on organic silicon compounds (siloxanes) and their highly detrimental ...

Chemical diffusion (D) and surface exchange (k) coefficients for SrFeO3-delta were measured using an electrochemical cell combined with electrochemical impedance spectroscopy (EIS) and potential step technique (PS) in the temperature range of 850-915°C. A value of ~ 4x10-5 cm2/s and a k value of ~ 8x10-5 cm/s were obtained at 900°C. Slow scan (0.5-3 microV/s) cyclic voltametry (CV) was performed in the same temperature range, using the same electrochemical cell to obtain oxygen nonstoichiometry data. The ox

In this study, we examine the parameters that govern the overall oxygen flux through a permeation membrane. The chemical diffusion (D) and the surface exchange (k) coefficients for oxygen in La0.6Sr0.4Fe0.8Co0.2O3-d were determined as a function of temperature using a specially designed electrochemical cell combined with impedance spectroscopy. Typically, D=1.7 10-5 cm2/s and k=3.6 10-4 cm/s in air at 900°C. These values were compared with literature 18O/16O isotope exchange data. Oxygen permeation measurem

Solid Oxide Fuel Cells (SOFC) is an interdisciplinary technology by excellence, necessitating combined knowledge and R&D from mechanical, chemical, electrical and materials science engineering. At LENI Laboratory at EPFL, SOFC cells and stacks are designed, tested and analysed in collaboration with industry, from small area single cells to now kW-range stacks integrated in a system. The hardware R&D effort is strongly assisted by, and dependent on, modeling activities, for both design (e.g. new geometries)

The Laboratory for Applied Mechanical Design (LAMD) designed, manufactured, and experimentally tested a novel steam-driven anode off-gas recirculation (AOR) fan for 10 kWel solid oxide fuel cell (SOFC) systems. Due to the dynamic steam-lubricated bearings, the AOR unit is expected to have a high lifetime, even at elevated rotational speeds and temperatures. Additional, the unit is oil-free, explosion-proof, very compact, and cheap to manufacture. The AOR fan diameter is at 19.2 mm and the nominal rotational

To improve the industry benchmark of solid oxide fuel cell systems (SOFC), we consider anode off-gas recirculation using a blower as an add-on to our next-generation SOFC system. Evolutionary algorithms compare the different design alternatives, i.e. co-flow or counter-flow stack operation with hot or cold recirculation. The system performance is evaluated through multiobjective optimization criteria, i.e. maximization of electrical efficiency and cogeneration efficiency. The results obtained suggest that i

This paper presents an experimental study of the impact of toluene on the performance of anode-supported (AS) Ni/YSZ SOFC operating at ∼800 °C, 0.25 A/cm2 fed with H2 and biosyngas. Toluene was added to the fuel stream and its concentration increased from ...

A tape casting co-sintering route is described in which thin dense layers of LaSrFeCoO3 (LSFC) have been formed on planar, porous MgO substrates 100- 200 micron thick. SEM analysis of the sintered structure showed that it was possible to eliminate most of the residual porosity in the LSFC layer, but maintain a porosity between 25 and 45% in the MgO support layer. The LSFC layer dit not reveal many cracks. The overall shrinkage of the co-sintered structure was about 25%. The LSFC layer topography was smooth

This paper presents the processing steps for producing thin planar and tubular oxygen separation membranes by thermoplastic forming of Ba0.5Sr0.5Co0.8Fe0.2O3-delta (BSCF) with polystyrene (PS) and stearic acid (SA) as binder. The influence of powder conten ...

The poisoning effect by hydrogen chloride (HCl) on state-of-the-art Ni anode-supported solid oxide fuel cells (SOFCs) at 750 degrees C is evaluated in either hydrogen or syngas fuel. Experiments are performed on single cells and short stacks and HCl concen ...

Planar SOFC stack technology based on a unique concept (SOFConnex™) uses structured gas distribution layers between unprofiled metal sheet interconnects and thin Ni-YSZ anode supported electrolyte cells. The layers are flexible both in material and designa ...

The deployment of renewable energy systems has been increasing steadily in recent years. The intermittency associated with the renewable electricity supply can be addressed through the usage of energy storage and release systems. In this framework, reversi ...

As the world shift towards sustainable energy solutions, solid oxide fuel cells (SOFCs) using non-carbon fuels like ammonia and hydrogen emerge as promising pathways to produce clean energy and enhance conversion efficiency. However, current implementation ...

One of the major limitations of the nickel (Ni) - yttria-stabilized zirconia (YSZ) anode support for solid oxide fuel cells (SOFC) is its low capability to withstand transients between reducing and oxidizing atmospheres ("RedOx" cycle), owing to the Ni-to- ...

A novel setup has been designed and mounted to investigate the local electrochemical and thermal behavior of a cell from a 4-cell short stack under reversible operation solid oxide fuel cell/solid oxide electrolyzer (SOFC/SOE). It consists in the partition ...

While the global fuel utilization of solid oxide fuel cells (SOFCs) is limited by the stack aging rate, the fuel excess is typically used in a burner, and thus limiting the system electrical efficiency. Further, natural-gas-fueled SOFCs require treated wat ...

Oxygen permeability measurements of Ba0.5Sr0.5Co0.8Fe0.2O3−δ (BSCF) disk shaped membranes fabricated by thermoplastic processing and sintered at different temperatures (1000–1100 °C), showed no influence of the grain size on the oxygen permeation fluxes. T ...

Stefan Diethelm

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Materials for Methane-fueled SOFC Systems

Integrated System Design of a Small-scale Power-to-Methane Demonstrator

The effect of SO2 on the Ni-YSZ electrode of a solid oxide electrolyzer cell operated in co-electrolysis

Solid oxide fuel cell anode degradation by the effect of siloxanes

Oxygen transport and nonstoichiometry in SrFeO3-delta

Oxygen transport through dense La0.6Sr0.4Fe0.8Co0.2O3-d perovskite-type permeation membranes

Solid Oxide Fuel Cell

Design and Experimental Realization of a Steam-Driven Micro Recirculation Fan for Solid Oxide Fuel Cell Systems

Towards the Next-Generation of Solid Oxide Fuel Cell Systems

The Impact of Toluene on the Performance of Anode-Supported Ni-YSZ SOFC Operated on Hydrogen and Biosyngas

Co-casting and co-sintering of porous MgO support plates with thin dense perovskite layers of LaSrFeCoO3

Ba0.5Sr0.5Co0.8Fe0.2O3-delta (BSCF) feedstock development and optimization for thermoplastic forming of thin planar and tubular oxygen separation membranes

Solid oxide fuel cell anode degradation by the effect of hydrogen chloride in stack and single cell environments

Impact of Materials and Design on Solid Oxide Fuel Cell Stack Operation

Cyclic degradation analysis of reversible Solid Oxide Cell short-stack

Advancing non-carbon energy: optimized and safely operated solid oxide fuel cell design for industrial feasibility

Design of experiment approach applied to reducing and oxidizing tolerance of anode supported solid oxide fuel cell. Part II: Electrical, electrochemical and microstructural characterization of tape-cast cells

Local electrochemical and thermal investigation of a segmented reversible solid oxide fuel cell and electrolyzer

Experimental characterization of a solid oxide fuel cell coupled to a steam-driven micro anode off-gas recirculation fan

A case study of the effect of grain size on the oxygen permeation flux of BSCF disk-shaped membrane fabricated by thermoplastic processing