Effect of Calcination Temperature on the Structural and Electrochemical Behaviour of Li-Based Cathode for Intermediate-Temperature SOFC Application

Abstract

A new strategy to reduce the operating temperature of the solid oxide fuel cell (SOFC) is needed to foster the progress of developing high-performance and stable SOFC as a solution to the thermal stress and degradation of the cell components induced by high-temperature SOFC. The use of lithium (Li) as a cathode can increase the cell’s efficiency, as it allows for faster ion transport and a higher reaction rate. This study presents an attractive approach to using a Li-based cathode by combining Li with cobalt (Co) to form LiCo0.6Sr0.4O2 (LCSO). In this work, a precursor consisting of Li, Co, and strontium (Sr) was prepared via the glycine-nitrate combustion method. The precursor was calcined at two different calcination temperatures (800 and 900 °C) prior to ink formulation and symmetrical cell fabrication in order to study the effect of calcination temperature on the structural and electrochemical behaviour of a Li-based cathode. The precursor LCSO powder was characterised using X-ray crystallography (XRD) to determine the crystal structure and composition of the developed LCSO. The electrochemical performance of the fabricated symmetrical cell was tested using electrochemical impedance spectroscopy (EIS) to obtain the cell’s resistance information, which is related to the cell’s ionic and electronic conductivity. SDC electrolyte with LCSO calcined at 800 °C has a higher crystallinity percentage and a more porous structure compared to LCSO calcined at 900 °C. The porous structure enhanced the electrochemical performance of the cell, where the symmetrical cell has the highest conductivity (0.038 Scm−1) with the lowest activation energy (0.43 eV). The symmetrical cell was also able to achieve 2.89 Ω cm2 of area-specific resistance (ASR) at 800 °C of operating temperature. In conclusion, the SDC electrolyte with LCSO calcined at 800 °C is the promising cathode material for SOFC applications. The result of this study can benefit the SOFC field of research, especially in the development of intermediate temperature-SOFC.