La-Doped BaCoO[sub 3] as a Cathode for Intermediate Temperature Solid Oxide Fuel Cells Using a LaGaO[sub 3] Base Electrolyte

Abstract

Cathodic behavior of BaCoO3 doped with La was investigated in this study for an intermediate temperature solid oxide fuel cell (ITFC). Electrical conductivity of BaCoO3 increased monotonically with an increasing amount of La doped for the Ba site at 1073 K pO2=10−5 normalatm. Cathodic overpotential at 1073 K decreased with increasing La content and attained a minimum at X=0.3­0.5 in Ba1−xLaxCoO3. Since the cathodic overpotential of Ba0.6La0.4CoO3 kept a small value at decreased temperature, Ba0.6La0.4CoO3 is the optimum composition for the cathode of an ITFC among BaCoO3 -based oxides. When La0.8Sr0.2Ga0.8Mg0.15Co0.05O3 was used for the electrolyte, the power density of the cell using Ba0.6La0.4CoO3 for the cathode at 1073 K attained a value of 550 mW/cm2, which is slightly higher than that using Sm0.5Sr0.5CoO3 for the cathode. In addition, a low cathodic overpotential of Ba0.6La0.4CoO3 was also maintained in air. 18O­16O exchange reaction was performed to estimate the surface activity for oxygen dissociation. It was found that BaCoO3 exhibits high activity for the oxygen exchange reaction. Therefore, superior cathode property was assigned to the high surface activity of BaCoO3. © 2002 The Electrochemical Society. All rights reserved.

Performance and stability of proton conducting solid oxide fuel cells based on yttrium-doped barium cerate-zirconate thin-film electrolyte

“…4 should be avoided to keep the electrochemical performance of BSCF cathode [53]. Further detailed interfacial electrochemical performance should be investigated to understand any beneficial or detrimental effects from the reacted interfaces.…”

Electrode materials: a challenge for the exploitation of protonic solid oxide fuel cells

“…The authors suggested that the formation of secondary phases between SSC and BCZY, namely BaCoO 3 and Sm 2 Zr 2 O 7 , is beneficial for the oxygen reduction because both phases are mixed electronic/ionic conductors. However, Ishihara et al [84] reported that BaCoO 3 only exhibits a low cathodic overpotential when Ba is heavily substituted with La (between 30 and 50 mol%). Furthermore, even though Sm 2 Zr 2 O 7 -based compounds are proton conductors, their conductivity is about two orders of magnitude smaller than that of BZCY [85,86]; thus, it is expected that Sm 2 Zr 2 O 7 formation would reduce the cell performance.…”

A Novel Composite Cathode for Low‐Temperature SOFCs Based on Oxide Proton Conductors

“…Additional phases such as BaCoO 3 and Sm 2 Zr 2 O 7 were identified in the XRD patterns. The BaCoO 3 -based phase is an excellent mixed conductor with high oxygen ion and electronic conductivity [16,17] whereas the Sm 2 Zr 2 O 7 phase is a proton conductor with relatively high proton conductivity. [18] This implies that firing of the BZCY-SSC composite cathode onto an BZCY electrolyte at proper temperatures could produce desirable phases for oxygen reduction in addition to forming strong bonding between the electrolyte and cathode.…”