LSGM Electrolyte Research Articles

Effect of MgO formation in the vicinity of Ni-SDC/LSGM interface on SOFC performance

An interfacial reaction between Ni-SDC anodes and the LSGM electrolyte was investigated using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) to clarify its effect on the SOFC performance. Highly resistive fine particles were formed in the vicinity of the Ni-SDC/LSGM interface as a result of the reaction between Ni and LSGM. TEM/EDX analyses revealed that these particles were MgO, which has a much lower electronic conductivity than Ni. The particles were localized on the surface of the Ni grains in the Ni-SDC anodes. The effect of MgO particle formation on the SOFC performance depended on the anode thickness. The particles significantly increased the area-specific ohmic resistance of thin anodes (less than 15 μm), but they hardly increased the resistance of thick anodes at all.

The Effect of LSGM Nanoparticle Dispersion in Ag-LSGM Composite Thin Film Cathode for LSGM Electrolyte Solid Oxide Fuel Cells

Different amounts of LSGM nanoparticles were dispersed in the silver thin film cathode using the RF magnetron sputtering method. The nanostructure of the Ag-LSGM composite thin film cathode was observed using a field emission scanning electron microscope, and the area specific resistance of the Ag-LSGM composite thin film cathodes was measured by the three-probe AC impedance method. The silver grains became smaller as the amount of the LSGM nanoparticles increased after annealing at 600 ° in air for 100 h. The non-charge-transfer resistance decreased and became constant with an increase in the amount of the LSGM nanoparticles dispersed in the Ag-LSGM composite thin film cathode.

Ag current collector for honeycomb solid oxide fuel cells using LaGaO 3-based oxide electrolyte

Honeycomb type solid oxide fuel cell (SOFC) using a Ag mesh as a current collector and La 0.9Sr 0.1Ga 0.8Mg 0.2O 3 (LSGM) as an electrolyte was studied for reducing production cost. When an Ag mesh was used as a current collector, the power density of the cell became lower than that of a cell using a Pt mesh due to the relatively worse contact caused by the lower calcination temperature, particularly in the case of the anode. The preparation method and the electrode structure were investigated for the purpose of increasing the power density of the cell using the Ag current collector. It was found that an interlayer of Ni–Sm 0.2Ce 0.8O 1.9 (1:9) between the NiFe–LSGM cermet anode and the LSGM electrolyte was effective for decreasing the pre-calcination temperature for anode fabrication. Much higher power densities of 300 mW cm −2 and 140 mW cm −2 at 1073 K and 973 K, respectively, were achieved by inserting an interlayer. These results for the power density of the cell using the Ag mesh current collector after the optimization of the electrode structure and the preparation procedure are close to those of the cell using the Pt mesh current collector cell presented in our previous work.

Novel K2NiF4‐Type Materials for Solid Oxide Fuel Cells: Compatibility with Electrolytes in the Intermediate Temperature Range

AbstractMany new materials have been identified as being of potential interest to solid oxide fuel cell developers. Recent work has suggested that materials of the La2NiO4 composition possess sufficient activity to act as an effective cathode. Whilst there have been many studies of the transport properties of materials of this family the reactivity with electrolyte compositions has received relatively little attention. In this work we have investigated the compatibility of La2NiO4 + d (LNO) with LSGM and ceria gadolinium oxide (CGO) electrolytes. It is clear that under an air atmosphere LNO reacts readily with CGO electrodes with the formation of a higher order Ruddlesden–Popper (Lan + 1NinO3n + 1) phase as one of the reaction products. In contrast, there is no evidence of secondary phase formation with LSGM electrolytes from the obtained diffraction data over a period of 72 h at temperatures up to 1,273 K.

Electrophoretic Deposition of Dense Sr‐ and Mg‐Doped LaGaO3 Electrolyte Films on Porous La‐Doped Ceria for Intermediate Temperature Solid Oxide Fuel Cells

AbstractThe application of the electrophoretic deposition (EPD) technique to the preparation of dense La0.8Sr0.2Ga0.8Mg0.2O2.8 (LSGM) electrolyte films for intermediate temperature solid oxide fuel cells (IT‐SOFCs) was investigated. Suspensions of LSGM were prepared in acetone + I2 + H2O dispersion media. The effects of water and iodine content, of the applied voltage, and of powder loading on the EPD rate were systematically studied using metallic substrates (Pt and stainless steel). This allowed to identify the suitable set of EPD process parameters that were used to deposit LSGM films on tape‐cast composite electrodes, composed of lanthanum‐doped ceria (La0.4Ce0.6O2 –x, LDC), polyvinylidene difluoride (PVDF) and carbon powders. After EPD, dense and crack‐free 15 μm thick LSGM films were obtained on porous LDC by co‐firing in air at 1,490 °C. Line profile analyses performed by energy dispersive X‐ray spectroscopy (EDS) did not reveal any interdiffusion of ions across the LSGM/LDC interface. The chemical and structural compatibility of LSGM with LDC was also checked by heat treating a mixture of the two powders (1:1 weight ratio) using the same thermal cycle as that of the LDC/LSGM bi‐layer co‐firing at 1,490 °C. EPD has thus proven to be a viable way for manufacturing anode‐supported LSGM electrolyte films.

Characteristics and performance of lanthanum gallate electrolyte-supported SOFC under ethanol steam and hydrogen

This study is focused on the electrochemical performance of perovskite-type materials based on doped LaGaO 3. La 0.8Sr 0.2Ga 0.8Mg 0.2O 3− δ (LSGM) and La 0.8Sr 0.2Ga 0.8Mg 0.115Co 0.085O 3− δ (LSGMC) were used as electrolytes and (Pr 0.7Ca 0.3) 0.9MnO 3 (PCM) and La 0.75Sr 0.25Cr 0.5Mn 0.5O 3− δ (LSCM) as cathode and anode material, respectively. LSGM and LSGMC electrolytes were prepared by tape casting with a thickness of about 600 μm. The performance of LSCM/LSGMC/PCM was slightly superior to that obtained on LSCM/LSGM/PCM at different temperatures in both humidified hydrogen and ethanol steam atmospheres, good values of power output in LSCM/LSGMC/PCM were 182 and 169 mW cm −2 using humidified hydrogen and ethanol steam as fuel, respectively, and oxygen as oxidant at 850 °C. Cell stability tests indicate no significant degradation in performance after 60 h of cell testing when LSCM anode was exposed to ethanol steam at 750 °C. Almost no carbon deposits were detected after testing in ethanol steam at 750 °C for >60 h on the LSCM anodes, suggesting that carbon deposition was limited during cell operation.

Electrical Performance of Anode Supported SOFC for LSGM Electrolyte using La9.33Ge6O26 Functional Layer

not Available.

Performance and Microstructure of Porous LSCF-Ag Cermet Cathode for LSGM Electrolyte Solid Oxide Fuel Cells

not Available.

SmBaCo 2O 5+ x double-perovskite structure cathode material for intermediate-temperature solid-oxide fuel cells

SmBaCo 2O 5+ x (SBCO), an oxide with double-perovskite structure, has been developed as a novel cathode material for intermediate-temperature solid-oxide fuel cells (IT-SOFCs). The electrical conductivity of an SBCO sample reaches 815–434 S cm −1 in the temperature range 500–800 °C. XRD results show that an SBCO cathode is chemically compatible with the intermediate-temperature electrolyte materials Sm 0.2Ce 0.8O 1.9 (SDC) and La 0.9Sr 0.1Ga 0.8Mg 0.2O 3− δ (LSGM). The polarization resistances of an SBCO cathode on SDC and LSGM electrolytes are 0.098 and 0.054 Ω cm 2 at 750 °C, respectively. The maximum power densities of a single cell with an SBCO cathode on SDC and LSGM electrolytes reach 641 and 777 mW cm −2 at 800 °C, respectively. The results of this study demonstrate that the double-perovskite structure oxide SBCO is a very promising cathode material for use in IT-SOFCs.

Electrochemical evaluation of La 0.6Sr 0.4Co 0.8Fe 0.2O 3− δ–La 0.9Sr 0.1Ga 0.8Mg 0.2O 3− δ composite cathodes for La 0.9Sr 0.1Ga 0.8Mg 0.2O 3− δ electrolyte SOFCs

The composite cathodes consisting of perosvkite material La 0.6Sr 0.4Co 0.8Fe 0.2O 3− δ (LSCF) and La 0.9Sr 0.1Ga 0.8Mg 0.2O 3− δ (LSGM) were prepared, and then studied for potential applications in intermediate temperature solid oxide fuel cells (SOFCs) with LSGM electrolyte. Both ac impedance spectroscopy and dc polarization measurements were performed in air within the temperature range of 600–800 °C under open circuit potential. The results showed that the addition of 40 wt% LSGM to LSCF (LSCF–LSGM40) resulted in lower interfacial resistance (0.24 Ω cm 2 at 800 °C) than other composite cathodes and was slightly lower than the single-phase LSCF cathode (0.28 Ω cm 2 at 800 °C). Although adding LSGM electrolyte material to the LSCF electrode did not improve the electrode performance much, it could buffer the thermal expansion coefficient (TEC) of LSCF, which is larger than that of LSGM electrolyte.

Self-supported LaGaO 3-based honeycomb-type solid oxide fuel cell with high volumetric power density

A La 0.9Sr 0.1Ga 0.8Mg 0.2O 3 (LSGM)-based honeycomb-type solid oxide fuel cell (SOFC) with a 0.5 mm thick electrolyte wall was successfully fabricated and operated. This cell shows a much higher volumetric power density than a ZrO 2-based cell in the temperature range from 973 to 1173 K. Detailed results of internal resistance analysis suggest that IR loss is the predominant internal resistance of the cell. Furthermore, improved power density is achieved by decreasing LSGM electrolyte wall thickness. The effective area power densities are about 0.50 and 0.27 W/cm 2 at 1073 and 973 K, respectively, using a 0.5 mm thick electrolyte wall. A 0.5 mm thick 4-wall cell was also successfully fabricated and operated at 1073 K; the estimated volumetric power density of this cell is as high as 600 W/L when five channels are used.

La 0.9Sr 0.1Ga 0.8Mg 0.2O 3 − δ-La 0.6Sr 0.4Co 0.2Fe 0.8O 3 − θ composite cathodes for intermediate-temperature solid oxide fuel cells

Solid oxide fuel cells with thin La 0.9Sr 0.1Ga 0.8Mg 0.1O 3 − δ (LSGM) electrolytes have the potential to provide high power densities down to at least 600 °C. The present study was on a candidate cathode material for such SOFCs: composites containing La 0.6Sr 0.4Co 0.2Fe 0.8O 3 − θ (LSCF) and LSGM. Symmetrical cathodes with LSCF contents of 30–70 wt.% were fired at temperatures from 1000 to 1300 °C on both sides of bulk LSGM electrolytes. No secondary phases were detected by X-ray diffraction for the firing temperatures tested. Cathode polarization resistance R p, measured using impedance spectroscopy, varied little with firing temperature despite substantial changes in cathode microstructure as observed by scanning electron microscopy. R p varied only slightly with LSCF content, reaching a minimum of ∼ 0.18 Ohm.cm 2 at 650 °C for 40–60 wt.% LSCF fired at 1100 °C. The R p value was stable over several hundred hours at a current density of 0.5 A/cm 2. The temperature dependence of R p yielded an activation energy of ≈ 1.7 eV for all compositions. Measurements versus oxygen partial pressure P O yielded R p ∝ P O2 0.20. SOFCs with LSCF-LSGM cathodes and thin LSGM electrolytes yielded a maximum power density of 0.57 W/cm 2 at 650 °C.

Effect of Sr and Mg Doping on the Property and Performance of the La1 − xSrxGa1 − yMgyO3 − δ Electrolyte

(LSGM) with various and levels were prepared and evaluated as a solid oxide fuel cell electrolyte. The electrical conductivity of LSGM was dramatically enhanced with the increase of both the Sr and Mg doping levels. The compositions with Sr and Mg were found to possess much higher conductivity than the other compositions at . The optimal composition was with the highest conductivity of 0.177 and at 800 and , respectively. The coefficient of thermal expansion (CTE) was measured and shrinkage probably due to phase transition was observed in the CTE curve. The correlation between the phase transition, thermal expansion, and electrical conductivity was discussed. The performance of various LSGM compositions was assessed through the electrolyte-supported cells using a anode over a LDC buffer layer and a (SCF) cathode. The single cell with the electrolyte gave the best performance among all the cells, i.e., a maximum power density of 1.23 and in wet at 800 and , respectively. A relatively stable cell performance with loss in power density was observed over under a constant current density of at . The power loss was mainly due to the increase in cathode overpotential. Co was found to diffuse across the interface from the SCF cathode into the LSGM electrolyte during the long-term testing, which might lead to a Co deficiency in the cathode and thus contribute to the observed degradation in the cathode as well as the cell performance.

High temperature electrode reactions of Sr and Mg doped LaGaO3 perovskite

High-temperature phase reactions of Sr and Mg doped LaGaO3 (LSGM) electrolyte with many electrode materials including Ag, Au, Pt, Sm doped CeO2 (CSO), Sr doped LaMnO3 (LSM), and Sm doped SrCoO3 (SSCO) were investigated systematically by solid-state reaction and X-ray diffraction (XRD) analysis. Phase change and formation of minor phases were observed as a function of temperature. Single cells of LSGM electrolyte coupling with different electrode materials have been fabricated and tested by in situ ac impedance and IV curve measurement. The performance of single LSGM button cells was relative poor due to the occurrence of detrimental interfacial reactions.

Plasma sprayed metal supported YSZ/Ni–LSGM–LSCF ITSOFC with nanostructured anode

Intermediate temperature solid oxide fuel cells (ITSOFCs) supported by a porous Ni-substrate and based on Sr and Mg doped lanthanum gallate (LSGM) electrolyte, lanthanum strontium cobalt ferrite (LSCF) cathode and nanostructured yttria stabilized zirconia–nickel (YSZ/Ni) cermet anode have been fabricated successfully by atmospheric plasma spraying (APS). From ac impedance analysis, the sprayed YSZ/Ni cermet anode with a novel nanostructure and advantageous triple phase boundaries after hydrogen reduction has a low resistance. It shows a good electrocatalytic activity for hydrogen oxidation reactions. The sprayed LSGM electrolyte with ∼60 μm in thickness and ∼0.054 S cm −1 conductivity at 800 °C shows a good gas tightness and gives an open circuit voltage (OCV) larger than 1 V. The sprayed LSCF cathode with ∼30 μm in thickness and ∼30% porosity has a minimum resistance after being heated at 1000 °C for 2 h. This cathode keeps right phase structure and good porous network microstructure for conducting electrons and negative oxygen ions. The APS sprayed cell after being heated at 1000 °C for 2 h has a minimum inherent resistance and achieves output power densities of ∼440 mW cm −2 at 800 °C, ∼275 mW cm −2 at 750 °C and ∼170 mW cm −2 at 700 °C. Results from SEM, XRD, ac impedance analysis and I– V– P measurements are presented here.

The effects of LSM coating on 444 stainless steel as SOFC interconnect

The effect of oxide (La0.9Sr0.1MnO3, LSM) coating on the commercial stainless steel (STS444) interconnect as SOFC interconnect was examined by measuring the polarization resistance (Rp) of LSCF (La0.6Sr0.4Co0.2Fe0.8) cathodes of various electrolyte-supported cells (La0.9Sr0.1Ga0.8Mg0.2 [LSGM], Ce0.9Gd0.1O2 [GDC10], or 8 mol% Y2O3-doped ZrO2 [8YSZ]). The electrochemical impedance of LSCF cathodes was monitored during ∼140 h in air at 600 and 700°C to determine the cathodic Rp values. With or without interconnect contacts, the magnitude of cathodic Rp value of LSGM electrolyte was similar to that of GDC electrolyte and much smaller than that of YSZ electrolyte. However, no apparent difference in the rate of increase was observed among the cathodes on the different electrolytes. Although the Rp value of the LSCF cathode in contact with LSM-coated STS444 was much reduced from that with uncoated STS444, the coating was not perfect to prevent the Cr evaporation from the interconnect and thus to avoid the degradation of LSCF cathode. Thus new coating methods or materials are needed to protect the LSCF cathode from the Cr poisoning.

Electrical and stability performance of anode-supported solid oxide fuel cells with strontium- and magnesium-doped lanthanum gallate thin electrolyte

Anode-supported solid oxide fuel cells (SOFCs) comprising NiO–samarium-doped ceria (SDC) (Sm 0.2Ce 0.8O 1.9) composite anode, thin tri-layer electrolyte, and La 0.6Sr 0.4Co 0.8Fe 0.2O 3 (LSCF)–La 0.9Sr 0.1Ga 0.8Mg 0.2O 3− δ (LSGM) composite cathode were fabricated. The thin tri-layer consisting of an 11-μm thick LSGM electrolyte layer and a 12-μm thick La 0.4Ce 0.6O 1.8 (LDC) layer on each side of the LSGM was prepared by centrifugal casting and co-firing technique. The performance of the cells operated with humidified H 2 as fuel and ambient air as oxidant showed a maximum power density of 1.23 W cm −2 at 800 °C. A stability test of about 100 h was carried out and some deterioration of output power was observed, while the open circuit voltage (OCV) kept unchanged. Impedance measurements showed that both the electrolyte ohmic resistance and the electrode polarization increased with time and the latter dominated the degradation.

The Effect of LSGM Nanoparticle Dispersion in Ag-LSGM Composite Thin Film Cathode for LSGM Electrolyte Solid Oxide Fuel Cells

not Available.

Sealing Glass of Barium-Calcium-Aluminosilicate System for Solid Oxide Fuel Cells

Abstract Glass-ceramic materials were developed as a sealant in the solid oxide fuel cell (SOFC) in the temperature range of 800 ∼ 850 °C. The glass materials were based on the glass and glass-ceramic in the BaO-CaO-Al 2O 3-SiO 2-La 2O 3-B 2O 3 system. The thermal expansion coefficient (TEC) decreased with lower Ba 2+ content and higher Ca 2+ content, but the glass transition temperature and crystallization temperature increased greatly with an increase in Ca 2+ content and a decrease in Ba 2+ content, when the other components in the sealant were invariable. The TEC of the sealant with Ba 2+ content of 25.4% was 10.8 × 10 −6 K −1 (temperature range from 25 to 850 °C), and its softening temperature was 950 °C. The TEC of the sealant accorded well with that of La 0.9Sr 0.1Ga 0.8Mg 0.2O 3 - 6(LSGM) with a mismatch of only 3%. The sealant had superior stability and compatibility with the LSGM electrolyte during the process of operation in SOFC. The weight loss of the sealant with Ba 2+ content of 25.4% was approximately zero after heat-treated at 800 °C for 500 h in H 2 and O 2 atmosphere, respectively.

Nickel-cermet anode for fuel cells with the LSGM electrolyte

The effect of some technological parameters (firing temperature, thickness of an interphase layer made of solid electrolyte Ce0.82Gd0.18O1.91 (GDC), the GDC electrolyte amount in nickel-cermet) on the electrochemical and electric properties of a nickel-cermet (Ni-GDC) anode intended for fuel cells with the La0.88Sr0.12Ga0.82Mg0.18O2.85 (LSGM) electrolyte is studied. The polarization resistance of such an electrode is shown to hardly depend on the thickness of the interphase layer (4.5–23.5 μm) and the GDC electrolyte amount in nickel-cermet and to increase with the anode firing temperature. It is established that the contact resistance is concentrated in cells with the developed nickel-cermet electrode at the GDC/LSGM interface. At a temperature of 700°C the developed anodes may ensure a current density of 1 A cm−2 at an overvoltage of less than 100 mV when using both moist hydrogen and a methane-oxygen mixture as the fuel.