Fabrication And Characterization Of Anode-supported Hollow Fiber Solid Oxide Full Cell

Hollow fiber solid oxide fuel cell (HF-SOFC) is a kind of micro-tubular cell,with an outer diameter of about1.0mm and thickness of200μm, and itsmicrostructure can be controlled achievably by the optimization of the fabricationparameters. Compared with traditional planar and tubular solid oxide fuel cell,HF-SOFC has some obvious advantages, such as its short start-up time, ahigh-volume power density, it can be sealed conveniently and current can collecteasily. In this study, a novel asymmetric anode-supported HF-SOFC was fabricated bythe spinning/phase inversion technology, a dense YSZ electrolyte layer was depositedonto the anode by dip coating, the cathode layer was prepared by brush painting.Moreover, the electrochemical characterization of the as-prepared HF-SOFC wasinvestigated in the temperature range of600-800oC.Firstly, NiO-YSZ anode supporter was successfully fabricated by a wetspinning/phase inversion process. The anode hollow fiber shows a highly asymmetricstructure with finger-like voids at the inner side and sponge-like pores at the outerside. With the comparison of the microstructure, porosity and electrical conductivityof anode prepared at different temperatures,1250oC keeping2h was chosen as theoptimum sintering condition. The porosity and electrical conductivity of Ni-YSZanode hollow fiber co-sintered at1250oC for2h was calculated to be approximately46%and126S/cm, respectively.Secondly, La0.8Sr0.2MnO3-δ(LSM) was choosen as the cathode material, in orderto verify the cell performance of the modified asymmetric anode hollow fiber. DenseYSZ electrolyte layer with the thickness of about6.5μm was deposited onto theanode hollow fiber by dip coating, LSM-YSZ as composite cathode and pure LSM ascathode current collection layer were prepared by brush painting, respectively. We getthe anode-supported NiO-YSZ/YSZ/YSZ-LSM/LSM hollow fiber solid oxide fuel cell. The performance of the as-prepared HF-SOFC was tested at650-800oC withhumidified H2(20mL/min) as fuel and ambient air as oxidant, respectively. The cellprovides the maximum power densities of285,446,549and708mW/cm~2at650,700,750and800oC, respectively. The maximum power densities are580,665,706,718and726mW/cm~2at the fuel flow rate of3,5,10,20and30mL/min at800oC,respectively. The fuel utilization efficiency of the cell are calculated to be40.26%,32.76%,16.41%,8.34%and5.31%, respectively.Finally, we synthesized the new mixed ionic and electro conductor cathodematerial Ba0.5Sr0.5Co0.8Fe0.2O3-δ(BSCF) by sol-gel method, and BSCF was preparedonto the GDC buffer layer by brush painting as cathode layer. Then theanode-supported NiO-YSZ/YSZ/GDC/BSCF hollow fiber solid oxide fuel cell wasobtained. The cell provides the maximum power densities of253,580, and920mW/cm~2at600,700, and800oC, respectively. So BSCF is an excellent cathodematerial and the discharge performance is very stable.