Microfabrication of model Solid Oxide Fuel Cells for synchrotron-based operando studiesFriday (26.06.2020) 12:10 - 12:30 Room 1
The MIEC Sr(Ti,Fe)O3-d (STF) gained much attention as new electrode material for its capability of working at intermediate temperatures both as cathode and anode by tuning its stoichiometry [3, 4]. Ni-doped STF (STFN) exsolves Fe-Ni nanoparticles (NPs) in a reducing atmosphere. NP exsolution boosts the performance of these IT-SOFC anodes by enhancing the H2 dissociative adsorption, reducing the anode polarization resistance and improving C tolerance. The underlying mechanisms and the reversibility of NP exsolution is a heavily debated topic, but if understood and controlled, it could be disruptive for SOFC technology. For this work, in order to understand the exsolution process and gain device-level insights at the gas/solid interface, model SOFCs suitable for synchrotron operando ambient pressure X-ray photoelectron spectroscopy / electron-yield absorption spectroscopies (AP-XPS/XAS) and electrochemical impedance spectroscopy (EIS) at high temperature in oxidizing or reducing atmospheres were fabricated using various microfabrication techniques (Fig.1) . These YSZ-electrolyte supported half-cells have 200 nm of non-stoichiometric STFN (or STF for reference) as working electrode deposited by pulsed laser deposition PLD, onto photolithographed Pt current collectors and a porous Pt counter electrode deposited by reactive sputtering. Here we present details of the cells fabrication process and some exemplary synchrotron based results. We discuss how dedicated synchrotron-based operando studies on model devices are extremely useful to study energy conversion processes that in turn, guide an application-oriented material (or device or component) optimization. Protocols for quality control are also critical upon each fabrication step of model devices to conduct experiments that result meaningful for the application.
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