Three alkaline earths and two rare earths jointly enhance activity and stability of a high-entropy iron perovskite electrode for symmetrical solid oxide fuel cells

Symmetrical solid oxide fuel cells (SSOFCs) have the great potential to be commercialized but remain a challenge of efficient electrode design. Here, we demonstrate that three alkaline earths and two rare earths metals jointly enhance the activity and stability of the iron perovskite electrode and discover a new efficient high-entropy iron-based perovskite electrode of Ce0.2La0.2Ba0.2Sr0.2Ca0.2FeO3-δ (CLBSCF) for SSOFCs. The CLBSCF is synthesized via Pechini method and shows enhanced structural stability, conductivity, and catalytic activity, compared to state-of-the-art La0.2Sr0.8FeO3-δ (LSF). Systematic characterization of symmetrical electrodes reveals the significant increase of oxygen vacancy and electrocatalytic activity of CLBSCF. CLBSCF electrode based half-cells electrode exhibit the lower polarization resistance of 0.065 Ω cm2 in air and 0.36 Ω cm2 in H2 than that with LSF electrode (0.12 Ω cm2 in air and 1.57 Ω cm2 in H2) at 850 °C. The single cell with CLBSCF achieves a higher peak power density of 571 mW cm-2 than that with LSF electrode (336 mW cm-2) at 850 °C. Long-term durability of SSOFC with CLBSCF electrode confirms its excellent stability. This work provides a design pattern for efficient high-entropy iron-based perovskite electrodes of fuel cells.