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, La_0.2Pr_0.2Nd_0.2Ba_0.2Sr_0.2Co_0.8Fe_0.2O_3−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°C, which is much lower than that of La_0.6Sr_0.4Co_0.8Fe_0.2O_3−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 180 h reversible cycling test. Our results show the high-entropy design can significantly enhance the activity and robustness of LSCF electrode for tubular R-SOCs.