Investigation Of Optimizing Microstructure Of Cathode For SOFC By Using Electrostatic Spray Deposition

Nowadays, the energy problem has been one of the most concerned international problems. Many scientists are dedicated to look for a more convenience, green and sustainable energy for the future. Solid Oxide Fuel Cell (SOFC) has attracted many researchers because of its green and high-effective property, and after several years work, the prospect of SOFC's commercial use is getting brighter. However, there are also some problems that now impede this prospect; the high operation temperature of SOFC is just one of them. A higher operation temperature may influence the stability and life time of the cell materials and it also confines the selective of the connection materials. This restriction that is caused by high temperature will be the hurdle for the commercial use of SOFC. Reducing cell's operation temperature can deal with these problems, but with the operation temperature reduced, the electrochemical performance of the cell will degrade. The ohmic resistance will increase and interfacial polarization resistance of electrode (especially at the cathode) will rapidly increase. To the problem of the ohimic resistance, the thinner electrolyte film and developing novel materials with higher ionic conductivity are two solutions. And to the electrode, an optimized microstructure of electrode will be an effective approach besides developing new materials.This paper combines the impregnation technique and electrostatic spray deposition (ESD) technique to optimize the microstructure of cathode. In chapter 1, the principle, materials and theory of SOFC is reviewed. And the purpose of this work is proposed based on it.In chapter 2, the results of the YSZ backbones deposited by using ESD technique are discussed. These discussions mainly focus on the influence of deposition temperature on the morphology of the backbone film, and the influence of the precursor solution concentration on the morphology. Conclusions are made that 3-D reticular morphology are more easily obtained at lower deposition temperature such as 300oC, and a ditch-like morphology can be obtained at higher deposition temperature such as 400oC or above. Otherwise, the poor adhesion of the film deposited at 250oC is also observed.In chapter 3, three kind of symmetric cells are examined and the influence of different morphology backbones on the cathode electrochemical performance is discussed. The impact of different current collection layer is also discussed. Finally, cell prepared with ESD deposited cathode is examined.