A non-sealed solid oxide fuel cell micro-stack with two gas channels

Non-sealed solid oxide fuel cell (NS-SOFC) micro-stacks with two gas channels were fabricated and operated successfully under various CH ₄/O₂ gas mixtures in a box-like stainless-steel chamber. The cells with an anode-facing-cathode configuration were connected in serial by zigzag sliver sheets. Each cell consisted of the Ni/yttria-stabilized zirconia (YSZ) anode, the YSZ electrolyte, and the Sm_0.2Ce_0.8O _1.9-impregnated (La_0.75Sr_0.25) _0.95MnO₃ cathode. In this configuration, to ensure the identical gas distribution over the electrode surfaces, two gas channels with small vents flanking the stacks were used as gas channels of methane and oxygen for anodes and cathodes, respectively. The selectivity requirement of both the anode and cathode for the oxidation and reduction of CH₄ and O ₂ was lowered and the sheets could extend the residence time of gas flow over the electrode surface. By the direct flame heat with a liquefied petroleum gas burner, the stacks presented a rapid start-up and full utilization of the exhaust gas. Eventually, an open-circuit voltage (OCV) of 1.8 V and maximum power output of 276 mW was produced by a two-cell stack. For a four-cell stack, a maximum power output of 373 mW was obtained.