Development of an Optimized Anode Functional Layer for Solid Oxide Fuel Cell Applications

Abstract

The main function of the solid oxide fuel cell (SOFC) anode is to provide the reaction sites for the electrochemical oxidation of the fuel gas. Thus, the anode material must be stable in the reducing environment and have sufficient electronic conductivity and catalytic activity for the fuel/gas reaction under operating conditions. A porous cermet made of Ni and yttria-stabilized zirconia (YSZ) is widely used as anode material. The network of Ni particles has a large catalytic activity and is responsible for the transportation of electrons from the electrode reaction site to the current collector. Open porosity is required for the electrode to supply fuel as well as for removal of the reaction products. The addition of YSZ is necessary to support the Ni particles, to inhibit nickel grain coarsening at the usual operating temperatures and to give the cermet a thermal expansion coefficient acceptably close to that of the other cell components. [1] The presence of YSZ in the anode is considered to be inactive for the electrode reaction. [1] An alternative approach is for the YSZ component to extend the active area of the electrode reaction into the bulk of the electrode. [2] Although sinterability of Ni is reduced with increasing YSZ content, increasing YSZ content also raises the internal resistance (IR) of the SOFC. The particle size and ratio of Ni/YSZ are critical for the performance of the Ni/YSZ cermet anode. [3,4] Deposition of a thin anode interlayer on the anode substrate with finer particles reduces ADVANCED

Fabrication and Power Densities of Anode‐Supported Solid Oxide Fuel Cells with Different Ni‐YSZ Anode Functional Layer Thicknesses

“…Although thicker anode support layers are desirable in order to assure mechanical strength, these thicker layers decrease the power densities of the cells due to a larger electrode resistance [7]. To overcome these obstacles, the effective use of an anode function layer (AFL) placed between the electrolyte and the anode support has been proposed in literature [8,[11][12][13]. To overcome these obstacles, the effective use of an anode function layer (AFL) placed between the electrolyte and the anode support has been proposed in literature [8,[11][12][13].…”

Study of the rheological behavior of an anode slurry and the microstructural properties of an anode functional film obtained by spray coating

“…Studies have been conducted to establish the best film thickness, porosity, and composition for the most part. Hassan et al observed that the rate of leakage of helium gas in leak tests decreases with increasing AFL thickness and stops at a thickness of 16 μm [14]. Kong et al found that a decrease in the thickness of the AFL leads to an increase in the electrical performance of the cell.…”

Microscopic techniques for analysis of ceramic fuel cells

“…SEM (Hassan et al, 2002) Optimizing of AFL Ni, YSZ Both the thickness and the Ni-content of AFL have significant effect to overall cell performance.…”