Exploring Electrochemical Properties of Ti-Containing Oxides as Anodes for SOFCs
Date
2019-01-23
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Abstract
Solid oxide fuel cell (SOFC) is an energy conversion device that converts chemical energy from fuels directly into electricity and heat without any combustion steps. It provides relatively high efficiency and a more intelligent way to generate energy from fuels. However, there are some issues associated with yttria-stabilised zirconia (YSZ) electrolyte and Ni-YSZ anodes, which deteriorate the performance of SOFCs and affect the worldwide market acceptance. The objective of this thesis is to explore the electrochemical properties of Ti-based hollandite-type and perovskite-type oxides as alternative anode for SOFCs. Hollandite-type Ba1.33Ga2.67Ti5.33O16, K1.33Ga1.33Ti6.67O16, K1.54Mg0.77Ti7.23O16 and perovskite-type NaLaTiO4, NaLa2Ti3O9.5, NaLa2Ti2.9Fe0.1O9.45, NaLa2Ti2.8Fe0.2O9.4, and La2Ti2O7 were synthesised. All compositions were subjected to phase analysis, electrical conductivity measurements in air and H2, and evaluation for their catalytic activity towards hydrogen oxidation reaction (HOR). Among the samples investigated, K1.54Mg0.77Ti7.23O16 showed the highest electrical conductivity of 2 S/cm at 800 oC in H2. In order to evaluate catalytic activity towards HOR, symmetrical cells were constructed on oxide ion conducting Sr- and Mg- co-doped LaGaO3 (LSGM) electrolyte. Smallest area specific resistance (ASR) of 1.1 cm2 was observed on the anode composition La2Ti2O7 + Fe + LSGM (1:1:1 vol. %) with 20 % porosity. Furthermore, gas phase K+/H+ exchange reaction was shown in K1.54Mg0.77Ti7.23O16 in H2 at elevated temperatures. Bond valence sum mismatch calculation showed that the ion exchange reaction happened along the 1D channel along c-axis.
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Cao, C. (2019). Exploring electrochemical properties of Ti-containing oxides as anodes for SOFCs (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.