Effect of composition and sintering temperature on YSZ/ScSZ bilayer electrolyte using cold-pressed method.

• Main Author: Zuraida Awang Mat
• Format: text::Thesis
• Language: English
• Published: 2023
• Institution: Universiti Tenaga Nasional

Solid Oxide Fuel Cell (SOFC) is a device that consists of three main components which are anode, cathode and electrolyte. The common electrolytes used for SOFC are Yttria-Stabilised Zirconia (YSZ), Scandia-Stabilised Zirconia (ScSZ), and Samarium-Doped Ceria (SDC). The main issue of SOFC is the high operating temperature that negatively influence its performance. To reduce the temperature without jeopardizing the SOFC performance, a method of using bilayer electrolyte is proposed. In this work, YSZ/ScSZ bilayerstructure electrolyte was chosen instead of conventional doping method due to limitation of doping method in choosing the balance mol% combination as well as the annealing temperature. To achieve the objective of this thesis work, which is to fabricate bilayer YSZ/ScSZ electrolyte by different compositions at sintering temperature of 1350 °C, 1450 °C and 1550 °C, the electrolytes has been successfully fabricated via Cold-Isostatic Pressed (CIP) method. CIP method was adapted due to its low cost approach compared to the other fabrication technique. The results showed that, the fabricated pellets using CIP method were dense with relative density of ~93 % - 97 %. The effect of the different compositions was also been investigated and the result showed that, the pellets with higher weight ratio of ScSZ exhibit a good ionic conductivity. Electrochemical Impedance Spectroscopy (EIS) measurement indicates that the ionic conductivity increases with increasing sintering temperature. The result also showed that the pellets that contains more ScSZ (BE4) are more stable and mostly have high ionic conductivity at all three sintering temperature. In comparison, regardless of sintering temperature, based on SEM image obtained, most pellets shows a good grain growth structure. From this research, we can conclude that, bilayer electrolyte of YSZ and ScSZ using Cold-Isostatic Pressed method is producible and can be used for future application. Based on this study, the best composition for YSZ/ScSZ bilayer electrolyte is BE41450 pellet.