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The cathode of a protonic ceramic fuel cell must be able to facilitate ion and electron transfer, while simultaneously possessing a high catalytic activity for steam generation and the dissociation of gas-phase molecules. In this study, the performance of a cathode for protonic ceramic fuel cells is optimized by employing a triple-component composite cathode design, which integrates proton conductors, mixed electronic–ionic conductors, and a catalytic layer. Additionally, two other composite cathodes are fabricated for comparison. Owing to its higher electrical conductivity but lower catalytic activity, the composite cathode with protonic ceramic and (Ba 0.95 La 0.05) (Fe 0.8 Zn 0.2)O 3-δ (BLFZ) exhibits lower ohmic resistance but poor catalytic activity compared to the composite cathode with protonic ceramic and Ba(Co 0.4 Fe 0.4 Zr 0.1 Y 0.1)O 3-δ (BCFZY). The triple-component cathode is fabricated by infiltrating BCFZY into a composite cathode composed of BLFZ and protonic ceramic, and both the ohmic and non-ohmic resistances of the cathode are optimized in CH 4 and H 2 fuels. In particular, the performance of CH 4 fuel is significantly improved by adopting a triple-component cathode. These results suggest a possible contribution of the oxygen reduction reaction at the cathode to the reformation of CH 4 at the anode. • Triple-component composite cathode (BCFZY/BLFZ/BCZY) were fabricated at low temp. • Optimization in ohmic and non-ohmic ASRs by BLFZ and BCFZY in the composite cathode. • Oxygen reduction reaction at cathode facilitates the methane reformation at anode. [ABSTRACT FROM AUTHOR]

Generally, the NiO composite anode becomes porous after reduction. To infiltrate additional catalysts such as Pd into the NiO-composite anode before reducing NiO to Ni, a porous NiO composite anode for protonic ceramic fuel cells (PCFCs) was fabricated in this study. The porous NiO composite was fabricated by adding graphite as a pore former along with CuO as a sintering agent. The addition of graphite increased the porosity of the NiO composite anode but resulted in poor sinterability, which was addressed by adding CuO as a sintering agent to the NiO composite anode. The Pd catalyst was added to the NiO-composite anode before reducing NiO to Ni. The composite anode for PCFC with three components, namely Ni, protonic ceramics, and a Pd catalyst, was obtained by reducing NiO to Ni during the measurement. The addition of the Pd catalyst improved the anode performance in methane fuel and hydrogen fuel by enhancing the catalytic activity for the electrochemical reaction on the surface. [ABSTRACT FROM AUTHOR]

The performance of composite cathodes with different cathode materials, such as (Ba 0.95 La 0.05) (Fe 0.8 Zn 0.2)O 3-δ (BLFZ), (Ba 0.5 Sr 0.5) (Co 0.8 Fe 0.2)O 3-δ (BSCF), and (La 0.8 Sr 0.2)CoO 3-δ (LSC), are investigated to find the effects of the oxygen reduction reaction (ORR) and hydration on the fuel cell performance of protonic ceramic fuel cells. BLFZ, which exhibits the highest degree of hydration among these three materials, demonstrates the best electrode performance in hydrogen fuel, although BLFZ shows poor ORR activity compared with BSCF and LSC. When LSC is added into the BLFZ composite cathode to enhance the ORR activity, the electrode performance in H 2 fuel improves slightly, but that in CH 4 fuel improves significantly, thereby resulting in an increase in the power density from 0.48 to 0.72 W/cm2 in CH 4 fuel at 600 °C. By analyzing the relaxation time distribution, the contributions of the ORR and hydration reaction at the cathode to the performance of H 2 and CH 4 fuels are investigated separately. It is demonstrated that the ORR activity and hydration reaction can be optimized simultaneously by infiltrating the ORR catalysts into cathode materials with high hydration. ■ Oxygen Reduction Reaction at cathode in PCFC facilitates CH 4 reformation at anode. ■ Hydration in cathode materials is essential for high performance of PCFC. ■ BLFZ was better than BSCF owing to high degree of hydration. ■ Addition of LSC to BLFZ as ORR catalyst enhances a power density of PCFC in CH 4 fuel. [ABSTRACT FROM AUTHOR]