Synthesis Of Novel Compound Materials And Design Of Novel Low Temperature Solid Oxide Fuel Cell

The energy problem and environment problem are very rigorous now due to the energy resources structure has been not satisfactory for a long period. This forces us to find new clean energy technology to alleviate and eliminate the current burden of energy and environment. Among the various available clean energy technologies, the SOFC technology stands out and thought as the most promising one. However, the SOFC technology still can’t satisfy application need in short term because there are still a lot of problems needs to be solved. A typical SOFC usually constructed with the structure of a dense ionic conductive electrolyte layer sandwithed between two pores binary(electron and ion) conductive electrodes layers. This special configuration enable its’ the function of a fuel cell but also bring in some disadvantage simultaneously. Electrolyte must be a pure ion conductive layer which narrows down the range of available materials. Any degree of electron leakage through the electrolyte layer will cause a reduction of power output. In order to obtain high ionic conductive, the SOFC need to operated at elevated temperate, this in turn bring in actual difficult in fabrication, maintance of stack and material compatibility. Mutilayer configuration, elevated operating temperature and high temperature synthesis route of ceramic, all of these feature cause expensive cost of row material, fabrication and maintance and make it difficult to design stack and seal it. Thus, it is quite necessary to abandon the tradition configuration to eliminate the restrictions on material and seek for novel design principle to lower the operating temperature and cost. The main purpos of this work is try to design and synthesis novel low temperature SOFC.In chapter 1: The evolution history of SOFC and the involved theory of model of thermodynamics and reaction kinetics are introduced in brief. Further theoretical study of energy conversion process is conducted and an explanation of electrical efficiency at the molecular level is found.Chapter 2: Terbium doped ceria was synthesized by sol-gel method and then incorporated with layer structured oxide material LNCA. The single cell fabricated with this composite achieved the peak power density of 190-610 m W cm-2 at 460-500°C, which is far better than that of the single cell with pure TDC electrolyte(60-152 m W cm-2 at 550-700 °C) and confirms that the obtained composite has enhanced ionic conductivity. Then one step coprecipitation method was used to synthesis the terbium coated sodium carbon C-TDC. Again the C-TDC was incorporated with layer structured oxide material LNCA(denoted as C-TDC/LNCA). The single cell with C-TDC/LNCA achieved a maximum power density of 350 m W cm-2 at 415°C.Chapter 3: In order to investigate the electrochemical properties of different composite material, C-TDC/LNCA 、 C-TDC/LSCF and C-TDC/LNCA/LSCF composites were used to fabricate fuel cell and compared with each other. It was discovered that C-TDC/LNCA composite showed best performance at around 500°C, while the C-TDC/LSCF composite showed best performance at about 600°C, and C-TDC/LNCA/LSCF composite demonstrating a medium performance at whole temperature range of 500-600°C.Chapter 4: A p-type layered oxide material with triple e/H+/O2- conducting property and a n-type binary e/ O2- conductive material TDC+Co are selected and used to design a novel p-n junction fuel cell. The obtained novel p-n junction fuel cell showed excellent performance at temperature below 600°C.Chapter 5: The main work of this paper is summarized in this chapter and a promising novel clean energy cycle of village is illustrated.