Rare Earth Metal Oxide Modified Nickel Anodes for SOFC

摘要

Aiming at the development of high durability and high performance anodes for low and intermediate temperature solid oxide fuel cells, rare earth metal oxide (La, Pr, Sm, ect.) modified nickel oxides were investigated for improving the interfacial contact between catalyst and electrolyte, enlarging of three-phase boundary and increasing cell performance towards methane fuel. Re-doped anode materials were prepared by the decomposition and solid state reaction method. It was found that rare earth metal oxide interacted or reacted with nickel oxide, which resulted in small sized and uniformly distributed oxide particles. Anode supported cells with these new anode materials were fabricated and investigated. Different from the loose contact between nickel particles and YSZ electrolyte particles in the conventional Ni-YSZ anode, rare earth metal oxide modified anodes led to intimate contact between the catalyst and YSZ electrolyte. Impedance results depicted the decreased polarization resistances in these cells and suggested an enlarged three phase boundary. Not only higher cell performances with hydrogen fuel on the modified cells than on the conventional were attained, but also the modified cells exhibited distinctly high performance for methane fuel. The performances of these cells were compared with the consideration of their differences in anode materials. The conversion mechanism of methane on anode was discussed. It was suggested that high activity for electrochemical oxidation and high activity for methane reforming were responsible for the high performance for methane fuel on the modified cells. The synergy of reactions in the reaction network resulted in the high performance of the ReNi-YSZ anode cell for direct methane fuel, which is near to the performance for hydrogen fuel. While for the conventional Ni-YSZ anode cell, the performance for methane fuel is lower much than it for hydrogen fuel.