A Low-Lewis-Acid-Strength Cation Cs+-Doped Double Perovskite for Fast and Durable Oxygen Reduction/Evolutions on Protonic Ceramic Cells

Improving the reaction kinetics and durability of air electrodes on protonic ceramic cells is effective for their commercialization but challenging. Here, we report our electrode design via a low-Lewis-acid-strength cation (Cs+) doping strategy on a double perovskite oxide with a detailed formula of PrBa0.9Cs0.1Co2O5+δ (PBCsC). At 600 °C, the PBCsC electrode demonstrates a low area-specific resistance (ASR) value of 0.3 Ω cm2 within 100 h without significant degradation due likely to the electron pair shift by the polarization distribution of ionic Lewis acid strength at A and B sites. At 650 °C, a full cell with the PBCsC electrode displays an encouraging peak power density of 1.66 W cm–2 in the fuel cell (FC) mode, a high current density of −2.85 A cm–2 (at 1.3 V) in the electrolysis (EC) mode, good operational stability in dual modes of FC and EC, and promising cycling durability of 20 cycles in ∼80 h.