Preparation of thin film SOFCs working at reduced temperature

SOFCs are expected to become competitive devices for electrical power generation, but successful application is dependent on decreasing working temperature from 1000 to 800 °C, without detrimental effects on resistance and on electrode processes. This requires a reduction of the stabilised zirconia electrolyte thickness and an optimisation of the electrodes and interfaces. We have studied the preparation of a thin film SOFC device working at intermediate temperatures (less than 850 °C). The electrolyte must be very dense and as thin as possible to avoid ohmic losses. Electrodes, anode and cathode, must be porous enough to enable the gas fluxes to go through. Ni/YSZ cermet anodes have been prepared by a conventional ceramic method and support the cells. Thin Yttria Stabilised Zirconia electrolytes (YSZ) have been deposited by RF sputtering, DC sputtering and spray pyrolysis onto a Ni/YSZ cermet. Thin film La_0.7Sr_0.3MnO₃ (LSM) cathodes have been deposited onto the electrolytes by a spray-pyrolysis method. We present here the preparation and the characterisation of each component and the electrochemical performance of such cells at 850 °C. Paper presented at the 5th Euroconference on Solid State Ionics, Benalmádena, Spain, Sept. 13–20, 1998.