High‐Performance Solid Oxide Fuel Cell with an Electrochemically Surface‐Tailored Oxygen Electrode

State‐of‐the‐art cathodes for solid oxide fuel cells (SOFCs), such as (La,Sr)MnO3–(Y2O3)0.08(ZrO2)0.92 (LSM–YSZ), suffer from sluggish oxygen reduction reaction (ORR) kinetics at reduced temperatures, leading to a significant decline in their performance. Herein, we report a tailored SOFC cathode with high ORR activity at intermediate temperatures using a simple but effective approach based on “electrochemical” surface modification. The proposed process involves chemically assisted electrodeposition (CAED) of a metal hydroxide (LaCo(OH)x) on LSM–YSZ surfaces followed by in situ thermal conversion of LaCo(OH)x to perovskite‐type LaCoO3 (LCO) nanoparticles during the SOFC startup. This method facilitates easy loading of the LCO nanoparticles with a precisely controlled morphology without the need for repeated deposition/annealing processes. An anode‐supported SOFC with the LCO‐tailored LSM–YSZ electrode exhibits a remarkably increased power density, approximately 180 % at 700 °C, compared with an SOFC with the pristine electrode as well as excellent long‐term stability, which are attributed to the beneficial role of the CAED‐derived LCO nanoparticles in enlarging the active areas for ORR and promoting oxygen adsorption/diffusion. This work demonstrates that controlled surface tailoring of the cathode by CAED could be an effective approach for improving the performance of SOFCs at reduced temperatures. Deposit for success: A tailored cathode for solid oxide fuel cells (SOFC) that has high oxygen reduction reaction activity at intermediate temperatures is fabricated by using a simple but effective approach based on “electrochemical” surface modification. An anode‐supported SOFC with (La,Sr)MnO3–(Y2O3)0.08(ZrO2)0.92 (LSM–YSZ) as electrode tailored using LaCoO3 exhibits a remarkably increased power density, approximately 180 % at 700 °C compared with a SOFC with the pristine electrode, as well as excellent long‐term stability.