Dennis Soysal

IDEAL-Cell, Innovative Dual mEmbrAne fueL-Cell: Fabrication and Electrochemical Testing of First Prototypes

The IDEAL-Cell concept is based on the junction between a PCFC anode/electrolyte section and a SOFC cathode/electrolyte section, through a mixed proton and oxide ion conducting porous ceramic membrane, operating in the temperature range 600-700°C. Recombination of ions takes place within the junction, or central membrane (CM), and water vapor is evacuated through open porosity. The first results on the fabrication of multilayered samples reproducing the IDEAL-Cell structure are reported here, together with electrochemical tests carried out on selected samples in order to evaluate the performances of the chosen materials and to demonstrate the feasibility of this innovative concept of fuel cell.

Improving Stochiometery and Processing of LSCF Oxygen Electrode for SOFC

New stochiometries of La1-xSrxCo0.2Fe0.8O3-a (LSCF) for the oxygen electrode of SOFC were developed. The functional layers were manufactured by atmospheric plasma spraying (APS) using TriplexPro gun. Processing of LSCF was optimized for high gas permeability and low decomposition of the powder with focus on high production rates. Studies on microstructure using optical microscopy, scanning electron microscopy (SEM) and x-ray diffraction (XRD) were linked to plasma spray parameters. As a critical factor for decomposition the dwell time of the particles inside the plasma was identified. Functional layers had an improved porosity of about 20 vol%. At 800°C, power densities of above 640 mW/cm² at 0.7 V were recorded with H2/air

Nanostructured Composite Cathodes by Suspension Plasma Spraying for SOFC Applications

In the metal supported SOFCs (MS-SOFCs), conventional sintering route for cathode layer appears problematic due to excessive oxidation of metal support in air at sintering temperatures and degradation of perovskites during sintering in low oxygen partial pressures. The novel process of suspension plasma spraying (SPS), capable of producing a wide variety of coating structures and compositions without any post-deposition sintering, is developed and evaluated in detail for the fabrication of cathode layers for MS-SOFCs. Composite cathodes of LSCF and CGO were developed and the influence of different cathode microstructures on fuel cell performance was examined. Four exemplary cathode coatings have been created, ranging from partially dense with small pores to highly porous layers preserving submicronic agglomerated structures. These cathode coatings have been tested on equal half-cells made of the same anode and electrolyte. The best performing microstructure had a power density of 798 mW/cm2 at 800°C. Microstructural differences could be attributed to different behavior and performance of the coatings.