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No full textTechnical Report del Dipartimento di Informatica dell'Università Ca' Foscari di Venezi
Ca2Fe1.95Mg0.05O5: Innovative low cost cathode material for intermediate temperature solid oxide fuel cell
No full textThe good oxygen ion conductivity makes brownmillerites suitable as electrode materials for SOFCs. In this contribution, we focus on Ca2Fe1.95Mg0.05O5 (CFMO) with the idea of evaluating this brownmillerite as a promising innovative and low-cost cathode material. The synthesis was made through citrate route, where a magnesium doping was carried out to emphasize Fe3+/Fe4+ redox couple and thus the electronic conductivity. The chemical and physical properties of the material were verified by XRD, H2-TPR, XPS, BET and SEM techniques. The material was electrochemically characterized as a cathode by EIS, obtaining promising ASR values (0.19 Ωcm2 at 800 °C). Furthermore, CFMO stability under different atmosphere conditions was confirmed by EIS investigation at different oxygen partial pressures. The material was activated by deposition of FeOx nanoparticles through co-deposition and infiltration; the effect of increasing amount (10 and 15 wt %) was also studied. The Ca2Fe1.95Mg0.05O5 based nanocomposites well perform as cathode materials and the electrocatalytic reduction of oxygen is enhanced by iron oxide. This is confirmed by a reduction of ASR to 0.17 Ωcm2 at 800 °C for CFMO with Fe2O3 15 wt % as the best result of the study
Synthesis and characterization of Ca2Fe1.95Mg0.05O5: innovative low cost material for Reversible Solid Oxide Cell
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Comparison of different infiltration amounts of CeO2 inside Ni-YSZ anodes to improve stability and efficiency of Single-Chamber SOFCs operating in methane
Full text linkElectrochemically active oxide-based anodes capable of working in Single-Chamber Solid Oxide Fuel Cells (SC-SOFCs) were developed. Their performance is related to the selectivity of the electrodes. Tests are carried out on lab-scale devices with YSZ pellets as solid electrolytes in electrolyte supported cells. Selecting methane as a fuel, a gas mixture in the ratio CH4/O2 = 2 was chosen. The Ni-YSZ (NiO:YSZ=60:40) anode was optimized through CeO2 nanocatalysts infiltration to enhance the anode catalytic activity and make its reduction easier. Several infiltration amounts were compared, from null to 15% of the electrode weight. Both symmetric and complete cells (with LSCF-based cathodes) were tested in H2 and CH4/O2. For increasing amounts of infiltrated CeO2, symmetric cells tests describe an area specific resistance (ASR) reduction from 40 Ω cm2 to 1.7 Ω cm2 in hydrogen and from 11 Ω cm2 to 3.9 Ω cm2 in the methane/oxygen mixture. While complete cells tests displayed an ASR drop from 30 Ω cm2 to 2.9 Ω cm2 in H2, and from 8.7 Ω cm2 to 4.3 Ω cm2 in the methane/oxygen mixture, while OCP and power grew from 478 mV and 3.7 mW cm-2 to 766 mV and 13 mW cm-
Electrochemical study of symmetrical intermediate temperature - solid oxide fuel cells based on La0.6Sr0.4MnO3 / Ce0.9Gd0.1O1.95 for operation in direct methane / air
No full textLa0.6Sr0.4MnO3 (LSM), which is considered a state-of-the-art solid oxide fuel cell (SOFC) cathode, is investigated for application as an anode in direct methane intermediate temperature - solid oxide fuel cells (IT-SOFCs). Ce0.9Gd0.1O1.95 (CGO) is used as the electrolyte. The characterized electrode is a composite LSM/CGO, prepared in two different configurations: LSM crushed electrospun nanofibers / GDC powders, and LSM powders / GDC powders. The electrodes are tested in both air and direct methane conditions. At 815 °C, the polarization resistance Rp = 1.6 Ωcm2 in air, and Rp = 0.15 Ωcm2 in methane. Since perovskite-type manganites may show poor stability in reducing atmosphere, electrode stability is investigated. It is found that LSM shows a reversible modification of the crystal structure, assuming a Ruddlesden-Popper (RP) structure when exposed to methane. The RP structure is expected to be more stable compared to the LSM single perovskite. Furthermore, the composite electrode is expected to benefit from the presence of CGO, which is stable in reducing conditions
Ruddlesden-Popper perovskite-based electrodes for Symmetric and Reversible Solid Oxide Electrolysers
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