Fabrication And Characterization Of Functionally Graded Cathodes Based On In-situ Formed Cobaltic Rare Earth Salts In Perovskite Oxide Form For Intermediate Temperature SOFCs

Solid oxide fuel cell (SOFC) is an all solid state generator that cantransform chemical energy of fuels directly into electrical energy byelectrochemical reaction. As a new power generation system, it has been aresearch focus in renewable energy for its high efficiency, flexible fuel,non-Pt and etc. After rapid development in the past30years, it has beencommercialized widely. With the decrease in working temperature, it’snecessary to reduce the electrolyte’s thickness. Recently, La1-xSrxTiO3-δsupported or metal-supported SOFC cell have be the research focus.However, sintering of cathode in air will oxidize the support. Therefore,sintering of cathode with high performance meets great challenge. Themain contents of this thesis are the fabrication of functionally gradedcathodes based on in-situ formed perovskite oxide. Then the preparationand characterization of IT-SOFC single cells are carried out. The specifictasks are as follows:The first chapter of the thesis outlines various fuel cells, and makes abrief introduction to working principles, classification and developmentshome and abroad. Finally, the contents of this research are included.Chapter2introduces key materials’(electrolyte, anode, cathode, etc.)performance requirements and their developments.Chapter3describes the preparation methods of NiO/YSZ anode,CGO cathode barrier layer, LSC/CGO, LSC cathode, and takes thermalgravimetric analysis and specific surface test of LSC precursor powders.Chapter4analyzes the fabrication of the half-cell. The NiO/YSZanode, NiO/YSZ functional layer and YSZ electrolyte green tape is deposited by tape casting, screen printing and co-sintering. CGO barrierlayer and graded cathode are deposited on the disk. This chapter alsodiscusses the problems of the preparation processes besides.Chapter5discusses the necessity to study functionally gradedcathodes based on in-situ formed and develops one available process. XRDpatterns of LSC after different heat treatments are analyzed. This processproves to be feasible.Chapter6tests single cell performance. The results show that thesingle cell at the working temperature800℃can obtain open-circuitvoltage of1.054V and the maximum power density of317mW/cm2. Thecauses that affect single cell performance are also discussed in detail.Chapter7summarizes the initial results and problems in experimentprocess, and finally makes an outlook for the fabrication of gradientcathode based on in-situ formed perovskite oxides.