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Title: Development of High Power Density Metal-Supported Solid Oxide Fuel Cells

Authors:
 [1]
  1. Lawrence Berkeley National Laboratory, 1 Cyclotron Rd Berkeley CA 94720 USA
Publication Date:
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE)
OSTI Identifier:
1401793
Grant/Contract Number:
AC02-05CH11231
Resource Type:
Journal Article: Publisher's Accepted Manuscript
Journal Name:
Energy Technology
Additional Journal Information:
Journal Volume: 5; Journal Issue: 12; Related Information: CHORUS Timestamp: 2017-12-11 04:26:08; Journal ID: ISSN 2194-4288
Publisher:
Wiley Blackwell (John Wiley & Sons)
Country of Publication:
Germany
Language:
English

Citation Formats

Tucker, Michael C. Development of High Power Density Metal-Supported Solid Oxide Fuel Cells. Germany: N. p., 2017. Web. doi:10.1002/ente.201700242.
Tucker, Michael C. Development of High Power Density Metal-Supported Solid Oxide Fuel Cells. Germany. doi:10.1002/ente.201700242.
Tucker, Michael C. Wed . "Development of High Power Density Metal-Supported Solid Oxide Fuel Cells". Germany. doi:10.1002/ente.201700242.
@article{osti_1401793,
title = {Development of High Power Density Metal-Supported Solid Oxide Fuel Cells},
author = {Tucker, Michael C.},
abstractNote = {},
doi = {10.1002/ente.201700242},
journal = {Energy Technology},
number = 12,
volume = 5,
place = {Germany},
year = {Wed May 17 00:00:00 EDT 2017},
month = {Wed May 17 00:00:00 EDT 2017}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1002/ente.201700242

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  • Nanosize yttria-stabilized zirconia (YSZ) was synthesized by a unique approach based on molecular decomposition. In this approach, yttria-doped BaZrO{sub 3} (Y-BaZrO{sub 3}) or yttria-doped Na{sub 2}ZrO{sub 3} (Y-Na{sub 2}ZrO{sub 3}) precursors were first synthesized from BaCO{sub 3}, ZrO{sub 2}, Y2O{sub 3} or BaCO{sub 3} and commercial YSZ for Y-BaZrO{sub 3}, and from Na{sub 2}CO{sub 3} and YSZ for Y-Na{sub 2}ZrO{sub 3}, by a conventional solid state reaction method. Then, the precursors were boiled to leach away the unwanted species, BaO or Na{sub 2}O, either in a dilute HNO{sub 3} solution in water in the case of Y-BaZrO{sub 3}, or inmore » de-ionized water in the case of Y-Na{sub 2}ZrO{sub 3}. During boiling in HNO{sub 3} or water, the insoluble residue of Zr-Y-O composition formed fine, nanosize YSZ particles. X-ray diffraction (XRD) and specific surface area measurements on the as-synthesized powders confirmed the formation of nanosize YSZ. A subsequent heating in air led to particle growth. However, for a treatment at a temperature as high as 1000 C, the particle size was well in the nanosize range. XRD showed that the as-synthesized YSZ powders, as well as those heated up to 1000 C, the maximum temperature the powders were heated to after leaching, are of cubic structure.« less
  • This report contains the following three parts. (1) An investigation into the use of direct liquid hydrocarbon fuels in single cell tests. (2) An analysis of residual stresses in anode-supported solid oxide fuel cells. (3) A manuscript on the synthesis of nanosize ceramic (electrode and electrolyte) powders. Nanosize YSZ powder was prepared by a unique approach, in which yttria-doped BaZrO{sub 3} or yttria-doped Na{sub 2}ZrO{sub 3} precursors were first synthesized by a solid state reaction. Then, then the unwanted species, BaO or Na{sub 2}O, was leached away by washing the precursors in a dilute HNO{sub 3} solution or in water.more » This led to the formation of very fine, nanosize yttria-stabilized zirconia (YSZ). The particle size of the as-synthesized YSZ powders was a few nanometers and increased to tens of nanometers after thermal treatment at a temperature as high as 1000 C. The as-synthesized as well as heat-treated YSZ powder was of cubic crystal structure.« less
  • This report summarizes the work done during the entire project period, between October 1, 1999 and March 31, 2003, which includes a six-month no-cost extension. During the project, eight research papers have, either been, published, accepted for publication, or submitted for publication. In addition, several presentations have been made in technical meetings and workshops. The project also has provided support for four graduate students working towards advanced degrees. The principal technical objective of the project was to analyze the role of electrode microstructure on solid oxide fuel cell performance. Prior theoretical work conducted in our laboratory demonstrated that the particlemore » size of composite electrodes has a profound effect on cell performance; the finer the particle size, the lower the activation polarization, the better the performance. The composite cathodes examined consisted of electronically conducting perovskites such as Sr-doped LaMnO{sub 3} (LSM) or Sr-doped LaCoO{sub 3} (LSC), which is also a mixed conductor, as the electrocatalyst, and yttria-stabilized zirconia (YSZ) or rare earth oxide doped CeO{sub 2} as the ionic conductor. The composite anodes examined were mixtures of Ni and YSZ. A procedure was developed for the synthesis of nanosize YSZ by molecular decomposition, in which unwanted species were removed by leaching, leaving behind nanosize YSZ. Anode-supported cells were made using the as-synthesized powders, or using commercially acquired powders. The electrolyte was usually a thin ({approx}10 microns), dense layer of YSZ, supported on a thick ({approx}1 mm), porous Ni + YSZ anode. The cathode was a porous mixture of electrocatalyst and an ionic conductor. Most of the cell testing was done at 800 C with hydrogen as fuel and air as the oxidant. Maximum power densities as high as 1.8 W/cm{sup 2} were demonstrated. Polarization behavior of the cells was theoretically analyzed. A limited amount of cell testing was done using liquid hydrocarbon fuels where reforming was achieved internally. Significant polarization losses also occur at the anode, especially at high fuel utilizations. An analysis of polarization losses requires that various contributions are isolated, and their dependence on pertinent parameters is quantitatively described. An investigation of fuel composition on gas transport through porous anodes was investigated and the role of fuel diluents was explored. This work showed that the molecular weight of the diluent has a significant effect on anode concentration polarization. This further showed that the presence of some molecular hydrogen is necessary to minimize polarization losses. Theoretical analysis has shown that the electrode microstructure has a profound effect on cell performance. In a series of experiments, cathode microstructural parameters were varied, without altering other parameters. Cathode microstructural parameters, especially three phase boundary (TPB) length, were estimated using techniques in quantitative stereology. Cell performance was quantitatively correlated with the relevant microstructural parameters, and charge transfer resistivity was explicitly evaluated. This is the first time that a fundamental parameter, which governs the activation polarization, has been quantitatively determined. An important parameter, which governs the cathodic activation polarization, and thus cell performance, is the ionic conductivity of the composite cathode. The traditional composite cathode is a mixture of LSM and YSZ. It is well known that Sr and Mg-doped LaGaO{sub 3} (LSGM), exhibits higher oxygen ion conductivity compared to YSZ. Cells were fabricated with composite cathodes comprising a mixture of LSM and LSGM. Studies demonstrated that LSGM-based composite cathodes exhibit excellent behavior. Studies have shown that Ni + YSZ is an excellent anode. In fact, in most cells, the principal polarization losses, at least at low fuel utilizations, are associated with the cathode. Theoretical analysis conducted in our group has also shown that anode-supported cells exhibit lower polarization losses compared to cathode-supported or electrolyte-supported cells. It is essential, however, that Ni + YSZ anode be not subjected to a re-oxidation step, such as may occur accidentally, as this can cause anode disintegration. A theoretical model was developed for reduction and re-oxidation kinetics of Ni-based anodes. The model was experimentally verified. In addition, criteria for the development of redox tolerant, yet Ni-based, anodes were established.« less
  • Anode-supported solid oxide fuel cells with Ni + yttria-stabilized zirconia (YSZ) anode, YSZ-samaria-doped ceria (SDC) bi-layer electrolyte and Sr-doped LaCoO{sub 3} (LSC) + SDC cathode were fabricated. Fuel used consisted of H{sub 2} diluted with He, N{sub 2}, H{sub 2}O or CO{sub 2}, mixtures of H{sub 2} and CO, and mixtures of CO and CO{sub 2}. Cell performance was measured at 800 C with above-mentioned fuel gas mixtures and air as oxidant. For a given concentration of the diluent, the cell performance was higher with He as the diluent than with N{sub 2} as the diluent. Mass transport through porousmore » Ni-YSZ anode for H{sub 2}-H{sub 2}O, CO-CO{sub 2} binary systems and H{sub 2}-H{sub 2}O-diluent gas ternary systems was analyzed using multicomponent gas diffusion theory. At high concentrations of the diluent, the maximum achievable current density was limited by the anodic concentration polarization. From this measured limiting current density, the corresponding effective gas diffusivity was estimated. Highest effective diffusivity was estimated for fuel gas mixtures containing H{sub 2}-H{sub 2}O-He mixtures ({approx}0.34 cm{sup 2}/s), and the lowest for CO-CO{sub 2} mixtures ({approx}0.07 cm{sup 2}/s). The lowest performance was observed with CO-CO{sub 2} mixture as a fuel, which in part was attributed to the lowest effective diffusivity of the fuels tested.« less
  • Anode-supported cells comprising Ni + yttria-stabilized zirconia (YSZ) anode, thin ({approx}10 {micro}m) YSZ electrolyte, and composite cathodes containing a mixture of La{sub 0.8}Sr{sub 0.2}MnO{sub (3-{delta})} (LSM) and La{sub 0.9}Sr{sub 0.1}Ga{sub 0.8}Mg{sub 0.2}O{sub (3-{lambda})} (LSGM) were fabricated. The relative proportions of LSGM and LSM were varied between 30 wt.% LSGM + 70 wt.% LSM and 70 wt.% LSGM + 30 wt.% LSM, while the firing temperature was varied between 1000 and 1200 C. The cathode interlayer composition had a profound effect on cathode performance at 800 C with overpotentials ranging between 60 and 425 mV at 1.0 A/cm{sup 2} and exhibitingmore » a minimum for 50 wt.% LSGM + 50 wt.% LSM. The cathodic overpotential decreased with increasing firing temperature of the composite interlayer in the range 1000 {le} T {le} 1150 C, and then increased dramatically for the interlayer fired at 1200 C. The cell with the optimized cathode interlayer of 50 wt.% LSM + 50 wt.% LSGM fired at 1150 C exhibited an area specific cell resistance of 0.18 {Omega}cm{sup 2} and a maximum power density of 1.4 W/cm{sup 2} at 800 C. Chemical analysis revealed that LSGM reacts with YSZ above 1000 C to form the pyrochlore phase, La{sub 2}Zr{sub 2}O{sub 7}. The formation of the pyrochlore phase at the interface between the LSGM/LSM composite cathode and the YSZ electrolyte limits the firing time and temperature of the cathode interlayer.« less