Synthesis and characterization of transition metal doped solid oxide fuel cell cathodes

Abstract

Fuel cells have become of great interest as a potential economical and clean candidate for alternative and environmental friendly power generation services. There are several types of fuel cells with large differences in application, size, cost and operating temperature range. Solid Oxide Fuel Cell (SOFC) is a high temperature fuel cell, dealing with generation of power as well as heat. This study explains a number of experimental studies on the cathode of the SOFC. The emphasis is on two important aspects, the effect of different cathode materials on the electrochemical performance of the electrode and the kinetics of the oxygen reduction reaction (ORR). The main purpose of the thesis is to progress a novel and high quality cathode materials for SOFCs working at intermediate temperature (500°C<T) range. It is aimed to develop the alternative for the conventional IT-SOFC cathode materials with better mixed ionic-electronic conductivity, high electrochemical activity and good oxygen reducing with better efficiency. The production of novel cathode electrodes used in IT-SOFC is aimed to employ cheaper metals (Ti, Fe, Co, Cr, Mn, V, B and Gd) by using superior properties of perovskite structure. The study concerned a comparison is made between four different cathode materials under identical conditions. The cathode types investigated LV3SF (La0.57V0.03Sr0.4FeO3-δ), LG10SC (La0.5Gd0.1Sr0.4CoO3-δ), LV05SM (La0.595V0.005Sr0.4MnO3-δ) and LV05SC (La0.595V0.005Sr0.4CoO3-δ) were successfully synthesized by sol-gel process and are characterized with XRD (X-Ray Diffraction) and XPS (X-Ray Photoelectron Spectrosopy). For electrical conductivity measurements, four-probe conductivity method was performed. Also for the electrochemical characterization of the electrodes impedance measurements were completed. Of the four cathodes, the LV05SC on YSZ showed the highest are area specific resistance. The results for other cathode materials were in good agreement with literature.