(398v) Inert-Substrate-Supported Tubular Single Cell for Direct Operation on Isooctane

Zhao, K., Washington State University
Ha, S., Washington State University
Norton, M. G., Washington State University
Solid oxide fuel cells (SOFCs) are electrochemical energy conversion devices with advantages of directly utilizing hydrocarbon fuels. Direct liquid isooctane SOFCs show promising application potential due to system simplicity and low operation cost. Nickel-containing anode has been widely used as the supporting layer for SOFC single cells because of its high conductivity and good electrocatalytic property for oxidation of fuel. However, when using hydrocarbons as fuel, the nickel in the anode suffers from performance deactivation due to the carbon deposition in the anode. The interaction between carbon and nickel results in noticeable volume expansion and loss of mechanical strength. Therefore, improving the structure stability of the single cell appears as an important issue for running SOFCs on cheap hydrocarbon fuels

To enhance the mechanical and performance stability of the single cell in hydrocarbon fuels, we designed an inert-substrate-supported tubular cell with a configuration of porous yttira-stabilize zirconia (YSZ) supporter/Ni anode current collector/Ni-Ce0.8Sm0.2O1.9 (SDC) anode/YSZ/SDC bi-layer electrolyte/La0.6Sr0.4Co0.2Fe0.8O3-δ cathode. As the YSZ displays good mechanical stability in various fuels in the fuel cell operating temperature, applying the porous YSZ as the supporting layer could enhance the structure and electrochemical performance stability of the cell in liquid isooctane fuel.

The initial electrochemical performance and performance stability of the tubular single cell has been investigated in hydrogen and isooctane as fuel. Multi-functional layers in the tubular cell were modified to reduce the ohmic and polarization resistances and improve the maximum power output. The single cell showed a good maximum power density of 298 mW/cm2 in hydrogen fuel. When changing the fuel from hydrogen to isooctane, it maintained over 70% of the initial performance obtained in hydrogen. In addition, active reforming catalyst (Ni-Mo-Ceria-Zirconia) was introduced into the tubular channel to internally reform hydrocarbon fuels and increase the performance stability. By applying the catalyst, the single cell exhibited excellent performance stability during 12 h operation in isooctane fuel. The results suggest the feasibility of applying the inert-substrate-supported cell in liquid isooctane fuel.