Enhanced Electrochemical Performance of Ca3Co4O9-δ-Sm0.2Ce0.8O1.9 Cathode by Sm0.2Ce0.8O1.9 Impregnation Method in SOFCs

Catalytic activity for redox reactions is crucial for solid oxide fuel cells (SOFCs) design to improve the electrochemical performance. In this work, an impregnation strategy is adopted as the primary design principle to achieve both high oxygen reduction reaction (ORR) activity and low polarization resistance. A misfit-layered oxide cathode, Ca3Co4O9-δ (Ca349), is studied, along with composite cathodes fabricated with Sm0.2Ce0.8O1.9 (SDC) (Ca349-SDC) and a Ni0.9Cu0.1Ox-SDC anode. Their electrochemical properties are characterized via electrochemical impedance spectroscopy (EIS) and current–voltage (I–V) measurements using symmetric cells and single cells, respectively. After impregnating the Ca349 cathode with SDC for four cycles, the minimum polarization resistance (Rp) reaches 0.07 Ω·cm2 at 800 °C, which is much lower than that of the pristine Ca349 cathode (0.31 Ω·cm2). The Ca349-SDC//SDC//Ni0.9Cu0.1Ox-SDC single cell delivers a peak power density of 662 mW·cm−2 at 800 °C, which is 453 mW·cm−2 higher than that of the Ca349//SDC//Ni0.9Cu0.1Ox-SDC single cell. This study not only advances the rational design of SOFCs but also provides a generalizable framework for next-generation electrochemical energy conversion technologies.