Achieve a high electrochemical oxidation activity by a self-assembled cermet composite anode with low Ni content for solid oxide fuel cells
Ni-based cermets are the most widely used anode materials for solid oxide fuel cells. Reducing the content of Ni is beneficial to anode stability but usually unfavorable for the catalytic activity. In this study, Ni-Ce 0.8 Sm 0.2 O 2-δ anode with a low Ni content is synthesized through a polymer-directed evaporation-induced self-assembly strategy. Ni distributes evenly in the anode, resulting in an enlarged triple-phase boundary region and improved reactivity of lattice oxygen in the oxide phase. The anode containing 5 wt.% Ni possesses the highest amounts of oxygen vacancies and Ce 3+ /Ce 4+ redox pairs that facilitates the charge transfer process, which is one of the rate-determining steps of anode reaction. Consequently, that anode shows the lowest polarization resistance of 0.014 Ω cm 2 at 700 °C, much lower than those of other Ni-based anodes prepared through conventional techniques such as impregnation and solid-mixing. With that anode, a single cell supported by a 480-μm-thick Ce 0.8 Sm 0.2 O 2-δ electrolyte layer exhibits the maximum power density of 270 mW cm −2 at 700 °C. The anode also shows a promising stability.
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