Microstructure and performance of anode for microtubular solid oxide fuel cells

Abstract

NiO-YSZ hollow fibers were fabricated via a phase-inversion spinning technique. An YSZ electrolyte film was dip-coated on the outer surface of the fiber and then co-sintered at 1450℃ to form electrolyte/anode hollow fiber half cell. The microstructure of the NiO-YSZ anode was modulated by controlling NMP/ethanol ratio of the inner coagulant during spinning process. Experimental results showed that, with the 1-Methy 1-2-Pyrrolidinone (NMP) content increase from 0 to 30wt%, 50wt%, 70wt% and 100wt%, the microscopy of the anode hollow fibers evolved from a sandwiched structure, i.e. finger-like pore/sponge voids/finger-like pore morphology, to a finger-pore-penetrating structure, leading to porosity increase of the anode. Meanwhile, gas tightness of YSZ electrolyte film, mechanical strength of the reduced dual-layer hollow fibers, and conductivity of anode could decrease. Microtubular fuel cells were fabricated by coating a porous Ag cathode onto the dense YSZ electrolyte film. The concentration polarization in the H2/air cell decreased with increasing the length of the finger-like pores. The microtubular SOFC made from the anode hollow fibers with 70wt% of NMP-ethanol as the inner coagulant demonstrated the minimum polarization resistance and the highest output performance with 662 mW/cm2 power density.