Intermediate Temperature SOFC Based on Fully Integrated Plasma Sprayed Components

This work addresses the fabrication of membrane-type SOFCs, operating at an intermediate temperature using all components fabricated by plasma spray technology, and to evaluate the performance of the SOFC single unit at a temperature range of 500-800 0C. Single cells composed of a LaSrMnO₃ (“LSM”) cathode, LaSrGaMgO₃ (“LSGM”) electrolyte and a Ni/YSZ anode, were fabricated in successive atmospheric plasma spraying processes. Plasma spraying processes have been optimized and tailored to each layer in order to achieve a high porosity cathode or anode layer as well as a high density electrolyte layer. Major effort has been devoted to the production of the LSGM electrolyte film with high density and free-cracking. Electrochemical impedance spectroscopy was used to investigate the conductivity of the electrode layers and particularly the resistance of the electrolyte layer. It was revealed that the heat treatment had a great influence on the specific conductivity of the sprayed electrolyte layer, and that the specific conductivity of the heat-treated one was dramatically increased to the same magnitude as that of a sintered LSGM pellet. The experimental results have demonstrated that the plasma spray process has great potential for the integrated fabrication of the medium temperature SOFC units.