Properties of CuMn1.5Ni0.5O4 spinel as high-performance cathode for solid oxide fuel cells

Spinel oxide cathode has made great progress in solid oxide fuel cells (SOFCs) because of its special characteristics different from perovskite. In this study, a spinel-structured SOFC cathode, CuMn1.5Ni0.5O4 (CMN), is proposed. Rietveld refinement shows that CMN takes the cubic structure of the space group of P4332. CMN shows a high conductivity of about 70.0–91.2 S cm−1 at 600–800 ºC in the air and exhibits good catalytic activity for oxygen. A symmetric cell with CMN-GDC composite cathode demonstrates a low Rp of 0.047 Ω cm2 at 800 ºC. The charge transfer of oxygen is the rate-limiting process at lower temperatures. The performance test results of the button cell with CMN-GDC composite cathode are excellent, with high power densities of 1342.4 mW cm−2 at 800 ºC. After a110h long-term test, the cell runs stably, and no microstructure damage is observed.