A high-entropy engineered perovskite oxide for efficient and stable LSCF-based air electrode of tubular reversible solid oxide cells

Developing highly active and stable air electrodes remains challenging for reversible solid oxide cells (R-SOCs). Herein, we report an A-site high-entropy engineered perovskite oxide, La0.2Pr0.2Nd0.2Ba0.2Sr0.2Co0.8Fe0.2O3−δ (HE-LSCF), and its electrocatalytic activity and stability property are systematically probed for tubular R-SOCs. The HE-LSCF air electrode exhibits excellent oxygen reduction reaction (ORR) activity with a low polarization resistance of 0.042 Ω·cm2 at 700℃, which is much lower than that of La0.6Sr0.4Co0.8Fe0.2O3−δ (LSCF), indicating the excellent catalytic activity of HE-LSCF. Meanwhile, the tubular R-SOCs with HE-LSCF shows a high peak power density of 1.18 W cm-2 in the fuel cell mode and a promising electrolysis current density of -0.52 A cm-2 at 1.5 V in the electrolysis mode with H2 (~10%H2O) atmosphere at 700 °C. More importantly, the tubular R-SOCs with HE-LSCF shows favorable stability under 180h reversible cycling test. Our results show the high-entropy design can significantly enhance the activity and robustness of LSCF electrode for tubular R-SOCs.