Electrochemical Impedance Analysis of Ni/CGO10-Based Electrolyte-Supported Cells

To obtain a better understanding of the behavior of Ni/CGO fuel electrodes, this work presents a comprehensive investigation of Ni/CGO10-based electrolyte-supported cells. Commercial Ni/CGO10|CGO10|3YSZ|CGO10|Ni/CGO10-based symmetrical cells were characterized between 550 – 975 °C at pH2 = 0.8 bar and pH2O = 0.2 bar and for different H2/H2O gas mixtures at 550 °C. Small electrode area, thin anodes and large gas flow rates were used to minimize mass transport contributions. The distribution of relaxation times (DRT) is calculated and based on the results, an equivalent circuit model is derived. Electrode process contributions on Ni/CGO were calculated by means of a complex non-linear square fit of the equivalent circuit model to experimental data. One low frequency and one middle frequency electrode process were identified and correlated to a surface and a bulk process, respectively. Apparent activation energy barriers for both processes were derived.