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The effects of Li 2 CO 3 and LiOH on the ionic conductivity of BaCe 0.9 Y 0.1 O 3 (BCY)-x%Li 2 CO 3 (x = 0, 5, 10 and 30) and BCY-y%LiOH (y = 0, 2, 5 and 8) composite electrolytes were investigated. Symmetrical cells with the structure of foam Ni–Ni 0.8 Co 0.15 Al 0.05 LiO 2 (NCAL)∖BCY-x%Li 2 CO 3 or y%LiOH∖foam Ni-NCAL and Pt∖BCY-x%Li 2 CO 3 or y%LiOH∖Pt were prepared with NCAL-coated foam Ni and porous Pt as symmetrical electrodes, respectively. The ionic conductivity test results of the cells with Pt as the symmetrical electrode showed that the addition of LiOH did not improve the ionic conductivity of the BCY electrolyte, while the addition of Li 2 CO 3 could significantly improve the ionic conductivity of the BCY electrolyte. The maximum power density of the cells with the structure of foam Ni-NCAL∖BCY-x%Li 2 CO 3 or y%LiOH∖foam Ni-NCAL decreases with the increase in the amount of Li 2 CO 3 or LiOH, which indicates that adding Li 2 CO 3 or LiOH to BCY via mechanical mixing did not improve the electrochemical performance of the cells with NCAL as the electrode, and the NCAL electrode has the greatest impact on the performance of the cells. The interface of Li 2 CO 3 and BCY should be a high-speed channel for ion conduction. Increasing the effective area of the interface between BCY and Li 2 CO 3 and optimizing its continuity in the electrolyte should be the main development direction for improving the ionic conductivity. • Adding Li 2 CO 3 could significantly improve the ionic conductivity of BCY electrolyte. • Adding LiOH cannot improve the ionic conductivity of BCY-LiOH composite electrolyte. • NCAL anode has the greatest impact on the performance of new structure SOFC. • Increase the effective interface area of Li 2 CO 3 /BCY is the key to enhance conductivity. [ABSTRACT FROM AUTHOR]

The electrochemical performance of the Ni 0.8 Co 0.15 Al 0.05 LiO 2 (NCAL) cathode was investigated by comparing it with the traditional La 0.4 Sr 0.6 Co 0.2 Fe 0.8 O 3-δ (LSCF) and LSCF/Ce 0.9 Gd 0.1 O 2-δ (GDC) cathodes with a GDC electrolyte-supported solid oxide fuel cell (SOFC). It is found that the electrochemical performance of the cells with the NCAL and NCAL/GDC cathode is better than that of the cells with the LSCF and LSCF/GDC cathode at 550 °C. The results of the electrochemical performance tests of the cells with different NCAL/GDC mass ratios (10/0, 9/1, 8/2, 7/3 and 6/4) show that the NCAL/GDC composite cathode with the mass ratio of 8/2 has the best electrochemical performance. XRD results show that when the sintering temperature is higher than 700 °C, the NCAL/GDC composite will undergo chemical reactions and generate new phases, reducing the performance of the composite cathode. XPS results show that a small amount of Li 2 CO 3 was formed on the surface of NCAL during cathode preparation, forming a special interface between NCAL, Li 2 CO 3 and GDC. At the NCAL-Li 2 CO 3 /GDC interfaces, due to the migration and aggregation of Li+ to the interface, a space charge region may be formed in which the Li+ enrichment may lead to the formation of the region with a high oxygen vacancy concentration. A very high oxygen vacancy concentration at the NCAL-Li 2 CO 3 /GDC interfaces will provide sufficient oxygen ion conductivity for oxygen reduction reaction (ORR) and reduce the activation energy of the reaction. NCAL will be a potential cathode material that can reduce the operating temperature of the traditional SOFC to 550 °C or lower. • Electrochemical performance of Ni 0.8 Co 0.15 Al 0.05 LiO 2 cathode was investigated. • NCAL cathode show very good catalytic activity for ORR. • NCAL/GDC composite cathode with mass ratio of 8/2 has the best performance. • NCAL react with GDC above 700 °C, resulting in poor performance of composite cathode. [ABSTRACT FROM AUTHOR]