Electrochemical Properties of Fe/Mn Doped CeO₂ Impregnation Modified Ni-YSZ Electrode for High Temperature Solid Oxide Cells

Solid oxide cells (SOCs) with Ni-YSZ fuel electrodes were prepared by using cast-screen printing method. Highly catalytically active materials, including Ce_0.9Fe_0.1O_2−δ (CFO), Ce_0.9Mn_0.1O_2−δ (CMO) and Ce_0.6Fe_0.1Mn_0.3O_2−δ (CFM), were prepared by using Fe/Mn doped CeO₂, which were then impregnated to modify the Ni-YSZ electrodes. Microstructure, properties and stability of the electrodes after impregnation modification were studied, with electrochemical tests combined with analytical characterization methods, such as scanning electron microscopy (SEM), X-ray diffractometer (XRD) and energy spectrometer. The highest power densities of the unimpregnated, CFO, CMO and CFM impregnation modified Ni-YSZ electrodes in H₂ (3 vol.% H₂O) at 850 ℃ were 526 mW·cm⁻², 724 mW·cm⁻², 706 mW·cm⁻² and 829 mW·cm⁻², respectively, while the electrolytic current densities in V_CO2:V_CO=50:50 at 850 ℃ at 1.8 V were 0.55 A·cm⁻², 1.39 A·cm⁻², 1.43 A·cm⁻² and 1.63 A·cm⁻², respectively. Obviously, the performance was significantly improved after the impregnation modification, with CFM to be the best modification agent. The CFM-impregnated Ni-YSZ electrode was characterized by using CO₂ electrolytic stability test and EDS element content analysis. The decay rate was only 3.7% after testing for 100 h and the C content was almost unchanged before and after the testing, indicating that the CFM-impregnated Ni-YSZ electrode has high stability and can suppress the generation of carbon deposition. Therefore, CFO, CMO, and CFM are promising impregnation modifiers to extend the length of the three-phase boundary (TPB), optimize the microstructure and improve catalytic activity and stability of the Ni-YSZ electrode.