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BackgroundSolid oxide electrolysis cell (SOEC) offers a promising method for converting H2O into H2 at high temperatures ranging from 600 °C to 850 °C. Glass sealants, which are crucial materials in SOEC, fulfill most criteria for an ideal sealant when appropriate glass components at suitable stoichiometric proportions are selected. Nevertheless, they exhibit certain drawbacks, including limited stability, elevated gas leakage rates, and suboptimal thermal cycling performance during the SOEC operation.PurposeThis study aims to evaluate the performance of Al2O3 added Ba-Si-Ca sealant for SOEC.MethodsFirstly, a new Ba-Si-Ca system sealing glass (glass-P) was developed to enhance its properties, such as the coefficient of thermal expansion, glass transition, and softening temperatures, and a series of alumina additions to glass-P, intended for use as the SOEC sealant, were prepared using curtain coating. Then, the coefficients of thermal expansion of these sealants were evaluated using a thermal expansion instrument. The leak rate of the sealants, as well as the impact of different alumina additives on the material's thermal shock resistance and chemical stability, were assessed via a 1-cell stack measurement for extended SOEC operation. Finally, the elemental distribution of the specimen was observed using scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (EDS).ResultsThe experimental results show that the leakage rate of the glass P-10 sealant is measured at 5.54×10-3 sccm∙cm-1, which is lower than that of glass P. After undergoing ten thermal cycles, the leakage rate of glass P-10 is found to be 2.275×10-2 sccm∙cm-1, lower than that of the others. An open circuit voltage (OCV) of approximately 1.169 V is recorded for glass P-10 after a 1 053-h test.ConclusionsThe addition of alumina to glass P significantly enhances the sealant's thermal stability and gas tightness.

In order to decrease oxide growth kinetics, maintain suitable conductivity and prevent Cr-volatilization of AISI 430 stainless steels (430 SS) as the interconnect for intermediate temperature solid oxide fuel cells (SOFCs), a Co Ni O spinel oxide protective coating has been successfully fabricated on the 430 SS specimen using a simple and cheap process with two steps: 1) electroplation of Co Ni alloy layer and 2) pre-oxidation treatment to convert the Co Ni alloy into spinel oxide. The Co Ni O spinel layer on the 430 SS (Co Ni O 430 SS) is dense and uniform with 8–10 μm thickness. And the Co Ni O spinel oxide protective coating consists of a main face-centered-cubic (fcc) NiCo 2 O 4 spinel phase and a minor fcc NiO phase. Compared with bare 430 SS, the oxidation resistance and the conductivity of the Co Ni O 430 SS have been improved remarkably under simulated typical SOFC operating cathode conditions (at 800 °C in air). After an isothermal oxidation test at 800 °C, the area specific resistance (ASR) of Co Ni O 430 SS is much lower and stable (0.1 Ω cm 2 for 100 h and 0.9 Ω cm 2 for 600 h) than that of bare 430 SS (1.2 Ω cm 2 for 100 h and 2.4 Ω cm 2 for 600 h). These performances of Co Ni O 430 SS imply that it can be a promising candidate interconnect for solid oxide fuel cell. [ABSTRACT FROM AUTHOR]

Reversible solid oxide cells (RSOCs) can efficiently render the mutual conversion between electricity and chemicals, for example, electrolyzing CO 2 to CO under a solid oxide electrolysis cell (SOEC) mode and oxidizing CO to CO 2 under a solid oxide fuel cell (SOFC) mode. Nevertheless, the development of RSOCs is still hindered, owing to the lack of catalytically active and carbon-tolerant fuel electrodes. For improving mutual CO-CO 2 conversion kinetics in RSOCs, here, we demonstrate a high-performing and durable fuel electrode consisting of redox-stable Sr 2 (Fe, Mo) 2 O 6-δ perovskite oxide and epitaxially endogenous NiFe alloy nanoparticles. The electrochemical impedance spectrum (EIS) and distribution of relaxation time (DRT) analyses reveal that surface/interface oxygen exchange kinetics and the CO/CO 2 activation process are both greatly accelerated. The assembled single cell produces a maximum power density (MPD) of 443 mW cm -2 at 800 °C under the SOFC mode, with the corresponding CO oxidation rate of 5.524 mL min -1 cm -2 . On the other hand, a current density of -0.877 A cm -2 is achieved at 1.46 V under the SOEC mode, equivalent to a CO 2 reduction rate of 6.108 mL min cm -2 . Furthermore, reliable reversible conversion of CO-CO 2 is proven with no performance degradation in 20 cycles under SOEC (1.3 V) and SOFC (0.6 V) modes. Therefore, our work provides an alternative way for designing highly active and durable fuel electrodes for RSOC applications.