Cobalt-based perovskites, namely lanthanum strontium cobaltite (LSC) and cobaltite-ferrite (LSCF) are de-facto the state-of-the-art air electrode materials for SOC application. LSC and LSCF demonstrates good electronic conductivity, sufficient mobility of the oxygen ions and high electrocatalytic activity at reduced temperatures (LSCF down to 700C, and LSC potentially below 650C). However, a sufficient social-economical issue in usage of the Co-based materials is rising divergence between modest supply and growing demands. As result, Co is included in lists of the so-called critical raw material (CRM). These facts have boosted research on the effective low-Co and Co-free electrodes. One of the expected surrogates for cobalt is copper. As was already reported [1-3], partial or fully substitution of cobalt with copper might be a promising and economically relevant option.

In present work we studied challenges related to the preparation of air electrodes based on the selected materials from La1-xBaxCuO3-δ and ReBa0.5Sr0.5CoCuO5+δ (where: Re –lanthanides) solid solutions with perovskite structure. To prepare a properly sintered electrode that are mechanically stable, adheres to the electrolyte and at the same time to mitigate migration of alkali earth elements to the ZrO2-based electrolyte, it is crucial not only to conduct the sintering process at the optimal temperature profile, but also optimize buffer layer. The work involved studies of air electrode layer preparation on the semi-technical, 5 cm x 5 cm, fuel electrode-supported cells by changing the sintering temperature, atmosphere in furnace, implementation of the sintering aids a a modification of the buffer layer. Later one included co-sintering of the of lanthanum doped ceria (LDC) on a top of GDC. The SEM and SEM-EDS techniques were used to analyze the microstructure and products of the sold state diffusion of the Sr/Ba. Electrochemical characterization of the cells was based on electrochemical impedance measurements of the cells in SOFC and SOEC modes in gas-tight steel cell with gold air-side current collector and Crofer 22APU grill as fuel-side one in the temperature range of 650-750 °C. Results demonstrated, that mechanically stable air electrode from La1-xBaxCuO3-δ or  ReBa0.5Sr0.5CoCuO5+δ cannot be fabricated on surface of the GDC as buffer layer without strong migration of the Sr and Ba toward 8YSZ electrolyte. Cells with dual LDC-GDC buffer demonstrated similar performance with LSC electrodes at 625-650 C. For the for the copper-based materials obtained performance might be considered as promising, however microstructural optimization of the layer is necessary to compete with state-of-the-art materials.