Abstract

The reproducible and commercial manufacturing of electrodes with enhanced electrochemical performance is of central importance for a successful technical realization of Solid Qxide Fuel Cell (SOFC) systems. The route of electrode fabrication for the SOFC by Wet Eowder Spraying (WPS) is presented. Stabilized suspensions of the powder materials for the electrodes were sprayed onto a substrate by employing a spray gun. After drying of the layers, binder removal and sintering are performed in one step. The major advantage of this process is its applicability for a large variety of materials and its flexibility with regard to layer shape and thickness. Above all, flat or curved substrates of any size can be coated, thus opening up the possibility of "up-scaling" SOFC technology. Electrodes with an enhanced electrochemical performance were developed by gradually optimizing the different process steps. For example an optimized SOFC cathode of the composition La065Sr03MnO3 with 40% 8YSZ showed a mean overpotential of about -50 mV at a current density of -0.8 A/cm2, with a standard deviation amounting to 16 mV (950°C, air). Such optimized electrodes can be manufactured with a high degree of reproducibility, as a result of employing a computer-controlled X-Y system for moving the spray gun. Several hundred sintered composites, comprising the substrate anode and the electrolyte, of 100x100 mm2 were coated with the cathode by WPS and used for stack integration. The largest manufactured electrodes were 240x240 mm2, and data concerning their thickness homogeneity and electrochemical performance are given.

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