Development of K-doped SFMO materials as cathodes for proton conducting solid oxide fuel cell

• Main Author: Lim, Chang Xue
• Other Authors: Su Pei-Chen
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2021
• Subjects: Engineering::Mechanical engineering
• Online Access: https://hdl.handle.net/10356/149746
• Institution: Nanyang Technological University

The objective of this project is to observe and determine the effect of potassium on the Oxygen reduction reaction characteristics on Sr2Fe1.5Mo0.5O6-δ (SFMO). By using solution combustion synthesis to incorporate potassium into the crystal structure of SFMO. The powder undergoes characterization by X-ray diffraction (XRD) and field emission scanning electron microscope (FESEM). After which, a slurry is made by combing the potassium doped SFMO KxSr2-xFe1.5Mo0.5O6-δ (KSFMOx) with α-terpineol and ethyl cellulose to create a slurry. The slurry is then painted on to both sides of a BaCe0.5Zr0.3Y0.16Zn0.04O3-δ (BCZYZ) pellet before undergoing annealing. After which, a thin layer of platinum paste is applied to the KSFMOx layer and annealed again to create a symmetric cell. The results from the tests show that at a calcination temperature of 1200°C, the particles tend to combine and clump together as the amount of potassium dopant increases. By lowering the calcination temperature to 1100°C, a pure SFMO phase can be maintained up to x = 0.2. From the thermogravimetric analysis (TGA), it can be concluded that as the amount of potassium dopant increases, the amount of oxygen vacancy increases as well. However, with the electrochemical impedance spectroscopy (EIS) test, it shows that polarization resistance is lowest at x = 0.05. This means that this is not from the amount of oxygen vacancy and more from electronic conductivity. To confirm this, DC-4 probe measurement and X-ray photoelectron spectroscopy can be utilized to identify the electronic conductivity.