Preparation of NdBaCo2O5+δ-Ce0.9Gd0.1O1.95 composite cathode by in situ sol-mixing method and its high-temperature electrochemical properties

NdBaCo2O5+delta-xCe(0.9)Gd(0.1)O(1.95) (NBCO-xCGO, x = 0 similar to 8 wt%) composite materials are prepared by novel solmixing method and evaluated as cathodes for intermediate-temperature solid oxide fuel cells. The chemical compatibility, thermal expansion behavior and electrochemical performance of NBCO-xCGO composite cathodes are studied. There is no chemical reaction between NBCO and CGO after sintering at 1100 degrees C for 12 h. Introducing CGO leads to the decrease of both thermal expansion coefficient and conductivity. Among all the composites, NBCO-5CGO shows the lowest polarization resistance of 0.034 Omega cm(2) at 700 degrees C. The anode-supported single-cell with NBCO-5CGO cathode exhibits a maximum power density of 1.0 W cm(-2) at 700 degrees C. The electrochemical impedance spectrum measurement combining with the distribution of relaxation times analysis proves that the addition of CGO nanoparticles significantly improves the surface oxygen dissociation process, and the charge transfer process is identified to be the reaction limiting step to control the oxygen reduction kinetics on NBCO-5CGO composite cathode. (C) 2021 Elsevier B.V. All rights reserved.