Solid oxidefuel cell composite cathodes prepared by infiltration of copper manganese spinel into porous yttria stabilized zirconia

Abstract

Composite cathodes of Cu_1.25Mn_1.75O₄ (CMO) spinel and yttria stabilized zirconia (YSZ) were made by infiltration of a precursor Cu–Mn gel into a porous YSZ matrix. Structural characterization showed no evidence of secondary phases but revealed a continuous network of CMO in the YSZ framework. Impedance spectroscopy and overpotential measurements revealed that the CMO–YSZ composite cathode had better electrochemical performance than the traditional LSM–YSZ cathode between 650 and 800 °C. A 50 wt% CMO impregnated YSZ cathode had a polarization resistance of 0.3 Ω cm² at 750 °C, compared to 8.5 Ω cm² for LSM–YSZ. Further investigation showed that charge transfer is the probable rate determining step for oxygen reduction in the CMO–YSZ cathode above 750 °C.