EIS analysis of electrode kinetics for La2NiO4 + δ cathode in contact with Ce0.8Sm0.2O1.9 electrolyte: from DRT analysis to physical model of the electrochemical process

The oxygen reduction kinetics on an La 2 NiO 4 + δ electrode for electrodes of different thicknesses was investigated by means of electrochemical impedance spectroscopy. Dependences of the polarisation resistance in the temperature range from 700 to 800 °C, and oxygen pressure range of 0.2–16 kPa were obtained. It was established that three relaxation processes determined the overall polarisation resistance. Probable electrode reaction stages were suggested: oxygen ion diffusion on the electrode/electrolyte interface, charge transfer in the adsorption layer, oxygen surface exchange, and diffusion in La 2 NiO 4 + δ . The influence of the electrode thickness on the electrochemical performance of La 2 NiO 4 + δ electrodes was shown. The correlations between the electrochemical data and isotope exchange data are discussed.