Hiroaki TAGUCHI
Thermochemical properties and performance of LaNi,FeO3 as the cathode for Solid Oxide Fuel Cells
Kazunori SATO
Solid oxide fuel cell(SOFC) is a promising power generation system owing to the high energy-conversion efficiency. It is important to develop new materials for anode, electrolyte, and cathode to improve the cell performance. In this research, thermochemical properties of La(Ni,Fe)O3 (LNF),which is a high electronic conductor, has been investigated in order to evaluate the availability as a new cathode material of intermediate-temperature solid oxide fuel cells. The performance of a cell consisting of the LNF cathode, yttria-stabilized zirconia (YSZ) electrolyte, and nickel-YSZ cermet anode has also been evaluated.
Measurements of the J-V characteristic, cathodic overvoltage, and interfacial resistance were carried out to examine the performance of the LNF and (La,Sr)MnO3 (LSM) cathodes at various oxygen partial pressures.
The interfacial resistance and activation overvoltage for LNF were found to decrease with decreasing oxygen pressures, which was contrary to those observed for LSM.This reaction was thought oxygen nonstoichiometry decreases in low oxygen partial pressure, and bivalent of Fe in LNF increases. This result can be explained by the non-stoichiometry causing a higher amount of the divalent state in iron ions of LNF, which results in a formation of favorable reaction sites for the reduction of adsorbed oxygen molecules near the phase-boundary between the cathode and electrolyte.
It was found that the cell performance was stable even under low pressures of oxygen for the LNF cathode. The maximum power density was improved by 30% when Ce0.8Sm0.2O1.9 (SDC) particles were mixed with LNF particles in order to form a LNF-SDC composite cathode.
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