Enhanced Performance of La0.8Sr0.2FeO3-δ-Gd0.2Ce0.8O2-δ Cathode for Solid Oxide Fuel Cells by Surface Modification with BaCO3 Nanoparticles

Abstract

Recently, Fe-based perovskite oxides, such as Ln1-xSrxFeO3-δ (Ln = La, Pr, Nd, Sm, Eu) have been proposed as potential alternative electrode materials for solid oxide fuel cells (SOFCs), due to their good phase stability, electrocatalytic activity, and low cost. This work presents the catalytic effect of BaCO3 nanoparticles modified on a cobalt-free La0.8Sr0.2FeO3-δ-Gd0.2Ce0.8O2-δ (LSF-GDC) composite cathode at an intermediate-temperature (IT)-SOFC. An electrochemical conductivity relaxation investigation (ECR) shows that the Kchem value of the modified LSF-GDC improves up to a factor of 17.47, demonstrating that the oxygen reduction process is effectively enhanced after surface impregnation by BaCO3. The area-specific resistance (ASR) of the LSF-GDC cathode, modified with 9.12 wt.% BaCO3, is 0.1 Ω.cm2 at 750 °C, which is about 2.2 times lower than that of the bare cathode (0.22 Ω.cm2). As a result, the anode-supported single cells, with the modified LSF-GDC cathode, deliver a high peak power density of 993 mW/cm2 at 750 °C, about 39.5% higher than that of the bare cell (712 mW/cm2). The single cells based on the modified cathode also displayed good performance stability for about 100 h at 700 °C. This study demonstrates the effectiveness of BaCO3 nanoparticles for improving the performance of IT-SOFC cathode materials.

Unraveling the promotional role of BaCO3 in the electrode reaction kinetics of an SmBaFe2O5+δ air electrode of reversible solid oxide cells

“…BaCO 3 was reported recently to be capable of signicantly reducing the polarization resistance of the electrode. 25,27,29,47 To conrm the function of BaCO 3 in the electrode reaction, calculations of the O 2 molecule adsorption on the surface of the BaCO 3 (100) and SBF(100) were carried out with the models shown in Fig. 3a We use BaCO 3 to inltrate the porous SBF electrode to enhance the electrode reaction kinetics.…”

“…It is reported that the increase in surface alkalinity could increase surface electron concentration and signicantly enhance the oxygen surface exchange process, thus reducing the polarization resistance. [24][25][26][27][28][29][30] For instance, aer inltrating 9.12 wt% BaCO 3 into La 0.8 Sr 0.2 FeO 3−d -Gd 0.2 Ce 0.8 O 2−d , the R p decreased by 50% at 700 °C compared to the bare sample. 27 Actually, the electrode reaction process consists of several elemental steps, including gas diffusion, oxygen molecule adsorption/dissociation, charge transfer, and oxygen ion migration across the interface between the electrode and electrolyte.…”

“…[24][25][26][27][28][29][30] For instance, aer inltrating 9.12 wt% BaCO 3 into La 0.8 Sr 0.2 FeO 3−d -Gd 0.2 Ce 0.8 O 2−d , the R p decreased by 50% at 700 °C compared to the bare sample. 27 Actually, the electrode reaction process consists of several elemental steps, including gas diffusion, oxygen molecule adsorption/dissociation, charge transfer, and oxygen ion migration across the interface between the electrode and electrolyte. Any slow process may become the rate-limiting step, affecting the entire electrode reaction.…”

“…It is reported that the increase in surface alkalinity could increase surface electron concentration and significantly enhance the oxygen surface exchange process, thus reducing the polarization resistance. 24–30 For instance, after infiltrating 9.12 wt% BaCO 3 into La 0.8 Sr 0.2 FeO 3− δ –Gd 0.2 Ce 0.8 O 2− δ , the R p decreased by 50% at 700 °C compared to the bare sample. 27…”

“…24–30 For instance, after infiltrating 9.12 wt% BaCO 3 into La 0.8 Sr 0.2 FeO 3− δ –Gd 0.2 Ce 0.8 O 2− δ , the R p decreased by 50% at 700 °C compared to the bare sample. 27…”