Potassium-doping double perovskite with improved oxygen reaction activity and durability cathode for dual-function ceramic electrochemical cells

Solid Oxide Fuel Cells (SOFCs) have attracted attention for their ability to convert the chemical energy stored in the fuel directly into electrical energy with high efficiency and cleanliness. We propose a systematic and rational strategy to enhance the properties of double perovskite materials, aiming to develop novel cathodes with superior electrochemical performance. Herein, a novel double-perovskite-type A-site potassium-doped PrBa 1– x K x Co 2 O 5+ δ ( x  = 0.1, 0.2; PBKC1, PBKC2) oxide demonstrated great potential to be a promising cathode for SOFCs. Density functional theory calculations suggested that doping with K + led to more oxygen vacancies and lower values of hydration enthalpy, which was helpful for the improvement of oxygen ion and proton concentration. As a result, the introduction of low-valent potassium increased the oxygen defects in the PrBaCo 2 O 5+δ (PBC) oxide, resulting in a slight decrease in conductivity, but increase in proton conductivity . The fuel cell constructed with the novel PBKC1 cathode exhibits promising performance, achieving maximum power densities of 1400 mW cm −2 at 800 °C and 940 mW cm −2 at 700 °C in both oxygen ion- and proton-conducting SOFC modes, respectively. These values surpass those of the cell utilizing the pristine PBC cathode. The present study proposes a systematic and rational methodology for the design of high-performance air electrodes specifically tailored for oxygen- and proton-conducting ceramic electrochemical cells .