Publication: Effect of composition and sintering temperature on YSZ/ScSZ bilayer electrolyte using cold-pressed method.
Date
2020-11
Authors
Zuraida Awang Mat
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Abstract
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.