Electrochemical characteristics of La0.8Sr0.2MnO3 (LSM)–scandia-stabilized zirconia (ScSZ) composite cathode

LSM–ScSZ composite electrode for solid oxide fuel cells (SOFCs) cathode application has been investigated for its oxygen reduction reaction (ORR) performance. The composition and sintering temperature of LSM–ScSZ were controlled to determine the optimized microstructure of the LSM–ScSZ electrode layer, considering its length of triple-phase boundaries (TPBs), and transfer of oxygen for cathode reaction. The electrochemical impedance spectroscopy (EIS) method with an equivalent circuit model was introduced to characterize the specific impedance of each sample. The results demonstrated that volume ratio of LSM:ScSZ = 6:4 sintered at 1200 °C sample showed the lowest total impedance of 0.031 Ω cm2 at 900 °C operating temperature, compensating slightly increased high-frequency impedance (RHF) of TPBs region with drastically improved the active surface of LSM area and their connectivity, which correspond to middle- and low-frequency impedance (RMF and RLF) value, respectively. This study suggests an integrated approach in the development of the SOFCs cathode design with the proper compositional ratio and sintering process via using commercial materials.