THE DEVELOPMENT OF INTERMEDIATE-TEMPERATURE SOLID OXIDE FUEL-CELLS FOR THE NEXT MILLENNIUM

Solid oxide fuel cells (SOFCs) have been rapidly developed for efficie nt power generation applications. One of the major activities at Imper ial College concerns the development of intermediate-temperature SOFCs , and the exploitation of cost-effective fabrication processes to addr ess the crucial technical problems which have hindered the commerciali sation of SOFCs. These involve the strategic investigation on the deve lopment of planar supported thin film electrolyte PEN (positive electr ode/electrolyte/negative electrode) structure [La(Sr)MnO3/ Zr(Y)O2-x/N i-ZrO2], and SOFCs based on La0.9Sr0.1Ga0.8Mg0.2O3-x (LSGM) electrolyt es for intermediate temperature operation (700-800 degrees C), and to exploit the electrostatic assisted vapour deposition (EAVD) and the fl ame assisted vapour deposition (FAVD) as novel, simple and cost-effect ive methods to manufacture SOFC components and multilayer PEN structur e on large area substrates in an open atmosphere, in one production st ep. In addition, efforts have been directed towards developing cathode /electrolyte systems to improve the conductivities in planar SOFCs. Sy stems such as La0.82Sr0.18MnO3/(Y2O3)(0.15)(CeO2)(0.85)/YSZ, La0.8S0.2 CoO3/(Y2O3)(0.15)(CeO2)(0.85)/YSZ, and La0.8Sr0.2CoO3/Ce0.8Gd0.2O1.9/Y SZ have been investigated and compared with La0.82Sr0.18MnO3/YSZ where YSZ is 8 mol% Y2O3 in ZrO2. The process, structure and properties of the cell components and cathodes have been examined using SEM, XRD and AC-impedance spectroscopy. The results from these new systems indicat e a superior performance in overall conductivity to the conventional L a0.82Sr0.18MnO3/YSZ system. (C) 1998 Elsevier Science S.A.