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Title: MEMS-based thin-film solid-oxide fuel cells

Authors:
; ; ; ; ; ;
Publication Date:
Research Org.:
Energy Frontier Research Centers (EFRC) (United States). Center on Nanostructuring for Efficient Energy Conversion (CNEEC)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1384340
DOE Contract Number:
SC0001060
Resource Type:
Journal Article
Resource Relation:
Journal Name: MRS Bulletin; Journal Volume: 39; Journal Issue: 09; Related Information: CNEEC partners with Stanford University (lead); Carnegie Institution at Stanford; Technical University of Denmark
Country of Publication:
United States
Language:
English
Subject:
catalysis (heterogeneous), solar (fuels), photosynthesis (natural and artificial), bio-inspired, electrodes - solar, defects, charge transport, materials and chemistry by design, synthesis (novel materials)

Citation Formats

An, Jihwan, Shim, Joon Hyung, Kim, Young-Beom, Park, Joong Sun, Lee, Wonyoung, Gür, Turgut M., and Prinz, Fritz B. MEMS-based thin-film solid-oxide fuel cells. United States: N. p., 2014. Web. doi:10.1557/mrs.2014.171.
An, Jihwan, Shim, Joon Hyung, Kim, Young-Beom, Park, Joong Sun, Lee, Wonyoung, Gür, Turgut M., & Prinz, Fritz B. MEMS-based thin-film solid-oxide fuel cells. United States. doi:10.1557/mrs.2014.171.
An, Jihwan, Shim, Joon Hyung, Kim, Young-Beom, Park, Joong Sun, Lee, Wonyoung, Gür, Turgut M., and Prinz, Fritz B. Mon . "MEMS-based thin-film solid-oxide fuel cells". United States. doi:10.1557/mrs.2014.171.
@article{osti_1384340,
title = {MEMS-based thin-film solid-oxide fuel cells},
author = {An, Jihwan and Shim, Joon Hyung and Kim, Young-Beom and Park, Joong Sun and Lee, Wonyoung and Gür, Turgut M. and Prinz, Fritz B.},
abstractNote = {},
doi = {10.1557/mrs.2014.171},
journal = {MRS Bulletin},
number = 09,
volume = 39,
place = {United States},
year = {Mon Sep 01 00:00:00 EDT 2014},
month = {Mon Sep 01 00:00:00 EDT 2014}
}
  • Nanostructured ZrO{sub 2} thin films were prepared by thermal atomic layer deposition (ALD) and by plasma-enhanced atomic layer deposition (PEALD). The effects of the deposition conditions of temperature, reactant, plasma power, and duration upon the physical and chemical properties of ZrO{sub 2} films were investigated. The ZrO{sub 2} films by PEALD were polycrystalline and had low contamination, rough surfaces, and relatively large grains. Increasing the plasma power and duration led to a clear polycrystalline structure with relatively large grains due to the additional energy imparted by the plasma. After characterization, the films were incorporated as electrolytes in thin film solidmore » oxide fuel cells, and the performance was measured at 500 °C. Despite similar structure and cathode morphology of the cells studied, the thin film solid oxide fuel cell with the ZrO{sub 2} thin film electrolyte by the thermal ALD at 250 °C exhibited the highest power density (38 mW/cm{sup 2}) because of the lowest average grain size at cathode/electrolyte interface.« less
  • No abstract prepared.
  • Lawrence Livermore National Laboratory (LLNL) has developed an improved method for fabrication of a thin film Solid Oxide Fuel Cell (SOFC) using a colloidal technique. Dense, crack-free, yttria-stabilized-zirconia (YSZ) films of up to 100 microns thick were deposited on nickel oxide/YSZ substrates and porous La{sub 0.85}Sr{sub 0.15}MnO{sub 3} (LSM) substrates. The new technique was also used to deposit a compositionally-graded film of YSZ and Ce{sub 0.8}Y{sub 0.2}O{sub 2} (CYO), which is useful for matching the thermal expansion coefficient to an adjacent layer. The SOFC is a solid-state electrochemical device that converts the chemical energy of fuel directly into electricity. Itsmore » efficiency and low emission positions SOFC on the short list of power generation technologies for the 21st century. However, commercialization efforts are hampered in part by the high cost of fabrication. One area of high cost is the fabrication of thin, defect free coatings. It is desirable to produce coatings that are in the range of 10-40 microns to minimize resistance yet maintain mechanical integrity. Deposition of films thicker than 10 microns in a single step using conventional techniques such as dip coating, spin coating, slurry painting or electrophoretic deposition generally results in cracking due to shrinkage when the solvent volatilizes. Therefore, generation of thicker coatings requires repeated thin film deposition, leading to long processing times and higher cost. LLNL's Colloidal Spray Deposition (CSD) method evaporates the solvent upon contact with the substrate, depositing a dense, finely divided powder film. This is achieved by heating the substrate to a temperature above or close to the boiling point of the solvent. When the fine mist is sprayed onto the hot substrate, the solvent evaporates rapidly, leaving a compact layer of powder. Continuous removal of solvent during extended deposition results in a thick defect-free film which is subsequently sintered. LLNL has optimized the aspects of technique including the nebulization and spraying process as well as the starting solution compositions. Both dense and porous coatings can be created, resulting in a fabrication method suitable for preparation of both the electrolyte as well as the electrodes. The CSD technique can be used to simplify fabrication and design of the fuel cell electrolyte and the electrodes. Fig. 1a shows a SEM micrograph of the cross section of a dense, crack-free, porous 13 {micro}m YSZ thin film on a porous Ni/YSZ (anode) disk. Fig. 1b shows a SEM micrograph of the cross section of a 70 {micro}m porous Ni/YSZ film on a YSZ disk. Crack-free films as thick as 100 {micro}m have been deposited. Fuel cells with CSD-deposited YSZ film on NiO/YSZ substrate and a Pt cathode were tested at 900 C in air/hydrogen where the NiO electrode was reduced to Ni. The open-circuit voltage was 1.1 V at 900 C, close to the theoretical voltage, indicating no leakage in the film. The short-circuit current density was 1.2 A.cm{sup -2} and the power density reached 0.55 W.cm{sup -2}. The CSD technique can also facilitate the use of materials that can improve fuel cell performance. For example, doped-ceria (CYO) has non-negligible electronic conduction in fuel conditions and cannot serve as an electrolyte by itself. A bi-layer of YSZ and doped-ceria has been proposed where the YSZ layer serves to block electrons. However, cracking and delamination have been observed due to the higher thermal expansion coefficient of doped-ceria. Relaxing the mechanical stress by grading the interface from YSZ to CYO is difficult to achieve using existing thin film deposition techniques. However, LLNL has been able to grade composition of a thin film over several microns (fig.2a). No visible interface was observed. Since YSZ and CYO form a complete solid solution at temperatures higher than 1300 C the graded film is believed to be a single phase material with composition changing progressively from pure YSZ to pure CYO. Fig. 2b shows the concentration profile of the graded film as determined by electron microprobe analysis. In addition to fuel cells, the CSD technique can be used to fabricate sensors, membranes, and other components. It can also be used to generate chemically inert, durable ceramic or metal coatings for components having different geometries for use in a variety of applications, particularly in harsh environments.« less
  • Thin film electrolytes of bilayer bismuth oxide/ceria are developed for intermediate temperature solid oxide fuel cells. Y 0.25Bi 0.75O 1.5 is deposited via Direct Current magnetron sputtering technique on an Sm 0.2Ce 0.8O 1.90 electrolyte film which is prepared by a dry-pressing process on an NiO–Sm 0.2Ce 0.8O 1.90 substrate. La 0.85Sr 0.15MnO 3-δ–Y 0.25Bi 0.75O 1.5 composite is applied onto the Y 0.25Bi 0.75O 1.5 film as the cathode to form a single cell. Cells with 6-μm-thick Y 0.25Bi 0.75O 1.5 and 26-μm-thick Sm 0.2Ce 0.8O 1.90 bilayer electrolytes exhibit improved open circuit voltages and power density compared withmore » those obtained with only Sm 0.2Ce 0.8O 1.90 electrolytes. The open circuit voltages are comparable and power densities are higher than those previously reported for solid oxide fuel cells with thick bilayer electrolytes using noble metals such as Pt as the electrodes. Impedance spectra show that the change of electrolyte resistance is negligible while the cathodic interfacial polarization resistance decreased significantly when the Y 0.25Bi 0.75O 1.5 layer is added to form the Sm 0.2Ce 0.8O 1.90/Y 0.25Bi 0.75O 1.5 bilayer electrolytes.« less