Phase Inversion and Electrophoretic Deposition Processes for Fabrication of Micro-Tubular Hollow Fiber SOFCs

Abstract

A novel combination of a phase inversion process followed by electrophoretic deposition was used to fabricate anode supported micro-tubular hollow fiber solid oxide fuel cells (SOFCs). The phase inversion process was used to produce 240 μm thick 60 wt% NiO - 40 wt% yttria-stabilized zirconia (YSZ) hollow fiber anode precursors with asymmetric porosity. Subsequently, electrophoretic deposition (EPD) was used to apply 40 μm thick, particulate YSZ electrolyte layers onto the un-sintered NiO-YSZ hollow fibers from a YSZ dispersion in ethanol at an applied electric field of ca. 22 kV m−1. The YSZ-coated NiO-YSZ fibers were sintered in a hydrogen atmosphere at 1500°C to produce gastight electrolytes. Two dispersions of YSZ and lanthanum strontium manganite (LSM) particles were then painted consecutively on top of the electrolyte layers, as ‘graded’ LSM-YSZ | LSM cathode precursors that were sintered at 1200°C. When fed with H2 fuel and air, a single such SOFC delivered peak power densities of 0.20, 0.18 and 0.14 W cm−2 during operation at 800, 750 and 700°C, respectively. A lumped parameter model, incorporating calculations of the contact, ohmic, activation and concentration polarization losses, is presented and the means are proposed by which certain potential losses may be obviated.