Kongfa Chen

Anode-Supported Micro-SOFC Stacks Operated under Single-Chamber Conditions

A micro solid oxide fuel cell (SOFC) stack with two series-wound single fuel cells was fabricated and operated successfully under single-chamber conditions. In this stack, the single cells were based on Ni/yttria-stabilized zirconia (YSZ) anode-supported YSZ membrane and were arranged with an anode-facing-cathode configuration in diluted methane and oxygen mixture gas between 600 and 750 degrees C. The performances of the stack were affected by the flow rate, gas composition, and furnace temperature. The effects of the narrow path between two cells on the electrodes and cells were discussed in detail, according to the open-circuit voltages (OCVs) and impedance spectra of each cell. At 700 degrees C, the maximum OCV of the whole stack was larger than 2.0 V at CH4/O-2=1.75 and 2, while the maximum power output of stack was about 371 mW at CH4/O-2=1 with a mass specific power of 552 mW/g. The performance indicates that such microstacks have potential for portable applications. (c) 2007 The Electrochemical Society.

Effect of the Cell Distance on the Cathode in Single Chamber SOFC Short Stack

Two-cell solid oxide fuel Cell (SOFC) stacks with an anode-facing-cathode configuration were operated in single chamber conditions, i.e., oxygen, methane, and nitrogen mixture. The effect of the distance between two cells on the cell performance was investigated. A single cell consisted of a porous NiO/8 mol % Y(2)O(3)-stabilized ZrO(2) (YSZ) anode support, a YSZ electrolyte membrane, and a Ce(0.8)Sm(0.2)O(1.9)-impregnated La(0.7)Sr(0.3)MnO(3) cathode. The experimental result demonstrated that the effect of the distance on the cathode was quite distinct when the distance (D) was equal to 2 mm. The distance effect could be negligible when D was larger than 4 mm. The effects were also varied with the ratio of methane and oxygen (M). An acceptable value of the distance was critical for the operation and performance of the stack

A Configuration for Improving the Performance of Coplanar Single-Chamber Solid Oxide Fuel Cell

A configuration for the coplanar, single-chamber solid oxide fuel cell has been proposed and operated successfully in a methane-oxygen mixture (CH 4 :0 2 = 2:1) with a total flow of 300 mL min -1 . It was fabricated by attaching the Ni/yttria-stabilized zirconia (YSZ) anode and the Sm 0.2 Ce 0.8 O 1.9 -impregnated La 0.7 Sr 0.3 MnO 3 cathode in two parallel grooves of the YSZ substrate. With the electrolyte wall fabricated between the anode and the cathode, the configuration obviously extends the conductive channel of oxygen ion transport and forms a gas separator between the electrodes, leading to a remarkable reduction in ohmic resistance, an elevation of open-circuit voltage, and, ultimately, an improved performance.

Ni/SDC Nanoparticles Modified La0.75Sr0.25Cr0.5Fe0.5O3 − δ as Anodes for Solid Oxide Fuel Cells

Fe-doped (La,Sr)CrO 3―δ (LSCrFe) oxide was modified as the anode of solid oxide fuel cells. Through vacuum-assisted impregnation processes, nanosized Sm-doped CeO 2 (SDC) and Ni particles were introduced into an anode backbone. With Ni and SDC coimpregnated LSCrFe anodes, the maximum power densities at 900°C reached 765 and 271 mW cm ―2 with H 2 and CH 4 as fuels, respectively, which were much higher than that with a nonmodified LSCrFe anode. Our results indicated that nanosized Ni particles played a primary role in performance enhancement. No carbon deposition was detected for all tested LSCrFe-based anodes.