Evaluation of the La2Ni1 − xCuxO4 + δ system as SOFC cathode material with 8YSZ and LSGM as electrolytes

Materials formulated as La2Ni1 − xCuxO4 + δ (0 ≤ x ≤ 1) have been synthesised to be evaluated as possible cathode materials in SOFCs. Their crystal structures have been investigated by high-resolution neutron powder diffraction at RT so as to map out the phase diagram. The thermal expansion coefficients have been determined to be in the range of 10.8–13.0 × 10− 6 K− 1. Total conductivity values are as good as 87 S cm− 1 at 580 °C for x = 0.4. In order to assess the performance of each oxide as cathode material, ac impedance measurements were carried out on La2Ni1 − xCuxO4 + δ/electrolyte/La2Ni1 − xCuxO4 + δ symmetrical cells with either LSGM or 8YSZ as electrolyte material. For all the electrode compositions studied, the best specific resistance (ASR) values were obtained with LSGM as electrolyte. The better performance of x = 0.4 and 0.6 (ASR ~ 1 Ω cm2 at 850 °C) compositions has been associated with the magnitude of the total conductivity and the matching of the TEC values of the cathodes with those of the electrolytes.