Solid Oxide Fuel Cells Based on Proton Conducting Electrolytes
- PDF / 2,300,344 Bytes
- 7 Pages / 612 x 792 pts (letter) Page_size
- 28 Downloads / 270 Views
0972-AA01-09
Solid Oxide Fuel Cells Based on Proton Conducting Electrolytes U. (Balu) Balachandran, Tae H. Lee, Beihai Ma, and Stephen E. Dorris Energy Systems Division, Argonne National Laboratory, Argonne, IL, 60439 ABSTRACT We have fabricated a solid oxide fuel cell (SOFC) using BaCe0.8Y0.2Ox (BCY) proton conductor as the electrolyte. An ≈15-µm-thick dense BCY film was prepared on a porous Ni/BCY cermet (i.e., ceramic/metal composite) substrate by a colloidal spray deposition technique. The gas-permeable Ni/BCY cermet substrate backed with nickel mesh was used as the anode, and a platinum paste backed with platinum mesh served as the cathode. The currentvoltage characteristics of the BCY-based SOFC were measured in the temperature range 600800°C using wet air on the cathode side and wet hydrogen on the anode side. The open-circuit voltage was close to the theoretical value at all operating temperatures. The power density of the fuel cell was ≈240 and ≈875 mW/cm2 at 600 and 800°C, respectively. INTRODUCTION Solid oxide fuel cells (SOFCs) have been extensively investigated as a clean and efficient power generation system. For conventional high-temperature SOFCs, yttria-stabilized zirconia has been used as the electrolyte. Due to a high activation energy for conduction, SOFCs based on stabilized zirconia are normally operated at temperatures above 750°C. This high operating temperature leads to the corrosion and incompatibility of materials, severely limits the selection of materials that might be suitable as the interconnect, and increases the difficulty of forming seals and manifolds. To overcome these problems, efforts are being made to develop electrolytes that can operate at intermediate temperatures. Most of the studies on intermediate-temperature SOFCs are based on doped cerates and lanthanum gallates as oxygen-ion conducting electrolytes. In SOFCs whose electrolyte is an oxygen-ion conductor, water is formed at the fuel-side electrode, which dilutes the fuel. An SOFC that uses a proton conductor as the electrolyte eliminates this problem, because water is generated at the air electrode, and not at the fuel electrode. The operating temperature of the SOFC can be reduced to ≈600°C by using proton conductors.
High-proton-conductivity electrolytes have been previously studied as an alternative for intermediate-temperature SOFCs. These electrolytes have mainly been in the form of thick (≥0.5 mm) disks due to the difficulty of preparing thin films [1-8]. To achieve high power density, however, SOFCs require thin-film electrolytes that minimize electrical losses. We have recently developed a colloidal spray deposition (CSD) method for fabricating BaCe0.8Y0.2O3-δ (BCY) thin films with thickness in the range of 8-30 µm [9, 10]. In this paper, we describe this method for preparing BCY thin films and report the performance of such a film in SOFCs operated at temperatures of 600-800ºC. EXPERIMENTAL BCY powder (particle size of 0.3-1.5 µm) was obtained from Praxair Surface Technologies Specialty Ceramics. Porous subst
Data Loading...
