Abstract: Various Ni-15％ Sm3＋(x) doped CeO2(Ni-SDC)composite anodes prepared by impregnation method were studied to unveil the role of SDC in improving the performance of Ni anode. The electrochemical properties and the power generation characteristics of the cells based on these anodes show that the performance of the cells were improved significantly by the addition of SDC into Ni due to the reduced ohmic resistance and anodic overpotential. The decrease of anodic overpotential after the introduction of SDC could be due to the extension of three-phase-boundary (TPB) and the increase of active sites for H2 oxidation. However, the introduction of SDC also leaded to an increase of activation energy, which resulted in a higher anodic overpotential for Ni-SDC anodes at low temperatures compared with pure Ni. The impedance spectra of Ni-SDC anode consisted of two arcs at high temperatures. The high frequency arc increased with the amount of SDC, while the low frequency arc showed no dependency on the amount of SDC. The high frequency arc could be related to the charge transfer reaction at TPB, and the low frequency arc could correspond to the disassociative adsorption of H2 and the following diffusion processes. 75％(w) Ni-25％(w) SDC/LSGM/SSC exhibited the highest power density among the cells studied, and the highest power density at 1073, 973, 873 K reached 1.1, 0.43, 0.14 W•cm－2, respectively. The cells also showed good stability.

Key words: Solid oxide fuel cell, Anode, Nickel, Samaria doped ceria(SDC), AC impedance