Study on fabrication and electrode properties for butane-fueled intermediate temperature solid oxide fuel cell

Abstract

Fuel cell is the energy conversion system. Among five types of fuel cells, which use hydrogen as a fuel, solid oxide fuel cell (SOFC) have been in the spotlight because of high efficiency, zero emission, and stable operation during long-term period. The conventional SOFC has problems associated with the fabrication and reliability during long-term operation at high temperature ($\gt900\degC$). Therefore, it is necessary to reduce the operating temperature to intermediate temperature ($600\degC-700\degC$). However, if the operation temperature is lower than $700\degC$, the power density is decreased sharply due to larger polarization resistance of cathode, and the hydrocarbons are not able to be directly used as a fuel because it is hard to occur the internal reforming into anode material at intermediate temperature. However, the reforming temperature of butane is low due to no aromatic composition. Moreover, butane is well infra structured and is easy to liquefy. Therefore, the operation of SOFC using butane as a fuel is very challenging issue at intermediate temperature. The primary purpose of this thesis is to develop intermediate temperature SOFC using butane as a fuel. However, three major issues should be solved in order to operate the SOFC using butane at intermediate temperature. Firstly, an increase in the catalytic activity of the cathode for the oxygen reduction reaction (ORR) must be obtained. Secondly, the high ionic conductivity should be maintained in solid electrolytes. Finally, the carbon formation at the anode side must be suppressed. The first problem can be solved using cobalt (Co) substitution, at the B-site in the complex perovskite-type $Pr_{0.3}Sr_{0.7}B_xB`_{(1-x)}O_{3-\delta}$ ; (PSBB`37X(1-X); B=Co, Fe; B`=Fe, Mn, and Ni; X=0, 0.3, 0.5, 0.7 and 1). Those cathode compounds are synthesized using the glycine nitrate process (GNP) and characterized by powder X-ray diffraction (XRD), thermal expansion coefficient (TEC) measurements, and ...