Cobalt‐Free High‐Entropy Perovskite La0.2Pr0.2Nd0.2Sm0.2Sr0.2FeO₃–δ Solid Oxide Cell Air Electrode With Enhanced Performance

This study investigates the novel cobalt‐free high‐entropy perovskite, La 0.2 Pr 0.2 Nd 0.2 Sm 0.2 Sr 0.2 FeO 3–δ (LPNSSF), as an air electrode material for solid oxide cells (SOCs). When testing a button cell with a single‐phase LPNSSF electrode, a current density of 0.55 A cm −2 is obtained at 0.7 V in fuel cell mode at 800°C. In order to mitigate the moderate electronic conductivity of LPNSSF, two approaches are explored. Incorporating a Co‐free highly conductive perovskite, LaNi 0.6 Fe 0.4 O 3–δ (LNF), either as an LPNSSF–LNF composite electrode or as a current collector layer (CCL), enhances the performance to 0.61 and 0.66 A cm −2 , respectively, under the same conditions. Microstructural features are studied by electron microscopy and show a rather dense structure of the CCL. Optimization of the current collector increases the current density further to 0.96 A cm −2 at 0.7 V in a 5 × 5 cm 2 anode‐supported cell at 800°C. This cell exhibits good long‐term stability in electrolysis mode in H 2 ‐H 2 O with 80% humidification. Continuous polarization of −0.69 A cm −2 is sustained for 1000 h, with an average degradation rate of 10 mV kh −1 after an initial run‐in phase. These findings demonstrate the promising performance and durability of LPNSSF as cobalt‐free SOC air electrode.