Direct power to hydrogen to power based on solid oxide cells with a high-performance Sr-Ba free air electrode

•Sr-Ba free La0.6Ca0.4Fe0.8Co0.2O3-δ is fabricated as the air electrode for RSOC.•The peak power density reaches 1.59 W cm−2 at 800 °C with H2 in SOFC mode.•The current density is 2.89 A cm−2 at 800 °C and 1.5 V with 50%H2O-50%H2.•Excellent reversible stability in both modes is achieved at 800 °C for 140 h. Reversible Solid Oxide Cell (RSOC) exhibits considerable potential for direct power to hydrogen and hydrogen to power with high efficiency. The Sr-Ba free cobalt-based air electrodes with suitable physicochemical characterization and considerable electrocatalytic activity are promising candidates for RSOC. However, the research concerning this material is limited. Herein, La0.6Ca0.4Fe0.8Co0.2O3-δ (LCFC) is explored as a Sr-Ba-free perovskite air electrode for RSOC in this work, and it exhibits a suitable value of TEC (14.66 × 10−6 K−1), excellent chemical stability, and promising conductivity. When fueled in H2(3%H2O) at 800 °C for power generation, the cell demonstrates a maximum power density of 1.59 W·cm−2, and it also demonstrates a high current density for power to hydrogen (2.89 A·cm−2 @800 °C) under 1.5 V with 50%H2O-50%H2. The performance of the cell in the two modes is also comparable to or even exceeds other cells reported in the literature. Besides, during a short-term reversible operation of 140 h in both hydrogen to power (SOFC) and power to hydrogen (SOEC) modes, the cell demonstrates promising reversibility and durability during different kinds of tests. All the results confirm the LCFC is an ideal candidate air electrode for RSOC.