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1.
Fabrication by co-sintering method of a multilayer pore-free electrode–electrolyte structure promising for use in solid-oxide fuel cell and its characteristics have been studied. A material with high ionic conductivity of La0.88Sr0.12Ga0.82Mg0.18O3–δ (LSGM) served as electrolyte. The composite electrode was formed from a 1: 2 mixture of LSGM and LSFG (La0.7Sr0.3Fe0.95Ga0.05O3–δ). The maximum temperature of the materials co-sintering ability is 1250°C. It was shown by the impedance spectroscopy that the polarization resistance of the LSGM–LSFG electrode is 0.14 Ω cm2 at 800°C.  相似文献   

2.
The electrochemical cells with electrodes based on La0.8Sr0.2MnO3 (LSM) and supporting solid electrolytes La0.88Sr0.12Ga0.82Mg0.18O2.85 (LSGM) and Ce0.80Sm0.20O1.90 (SDC) were studied comparatively. Characteristics of LSM electrodes and composite electrodes comprising a mixture of LSM and electrolytes of different origins [LSGM, SDC, and Zr0.82Sc0.18O1.91 (SSZ) in the mass ratio of 1:1] were analyzed. It was shown that: 1) the electrode polarization conductivity and the ohmic resistance of the cells with the LSM–LSGM composite electrodes on the LSGM and SDC electrolytes had very similar values, while they were largely different from all the other electrodes, 2) the electrochemical activity of the electrodes on the SDC electrolyte was much higher than on the LSGM electrolyte, and 3) the ohmic resistance of the cells with the SDC electrolyte corresponded to the electrolyte resistance, whereas, the ohmic resistance of the cells with the LSGM electrolyte was much larger than the electrolyte resistance. The obtained results are due to the interaction between the LSM and LSM-containing electrodes with the LSGM electrolyte during sintering, leading to the formation of a product with a very low conductivity.  相似文献   

3.
Preliminary progress is reported in this communication in building a planar anode-supported low-temperature solid oxide fuel cell (SOFC) stack based on gadolinia-doped ceria (GDC) electrolyte, i.e. fabrication and characterization of a Ø80 planar bilayer structure composed of GDC electrolyte film and Ni–GDC anode substrate. The anode substrates were prepared from mixtures of NiO, GDC, and carbon black by die-pressing. After pre-firing to remove the carbon black, the anode substrates were deposited with a GDC layer using a spray coating technique. The green bilayers of anode substrate and electrolyte film were then co-sintered at 1500 °C for 3 h. Through proper control of the sintering process, bilayer structures with excellent flatness were achieved after co-sintering. Scanning electron microscopy (SEM) observation indicated that the electrolyte film was about 22 μm in thickness, highly dense, crack-free, and well-bonded to the anode substrate. Small disks which were cut out from the Ø80 bilayer structure were electrochemically examined in a single button-cell mode incorporating a (LaSr)(CoFe)O3–GDC composite cathode. With humidified hydrogen as the fuel and air as the oxidant, the cell demonstrated an open-circuit voltage of 0.884 V and a maximum power density of 562 mW/cm2 at 600 °C. The results imply that high-quality anode-supported electrolyte/anode bilayer structures were successfully fabricated. Based on them, planar anode-supported SOFC stacks will be assembled in the future.  相似文献   

4.
Lowering the working temperature of solid oxide fuel cells (SOFCs) is the main trend in their development, which requires selection of materials for electrolyte and electrodes. A highly conducting lanthanum gallate-based electrolyte is a promising material for creating medium-temperature SOFCs. The electrochemical characteristics of the La0.6Sr0.4Fe0.8Co0.2O3 ? δ cathode that contacted with the La0.88Sr0.12Ga0.82Mg0.18O2.85 electrolyte subject to electrode formation temperatures have been investigated. It was found that at optimum bake-on temperatures of 1200–1250°C, the cathode polarization resistance at 800°C was ~0.08 Ohm cm2, which is comparable to the world’s best achievements.  相似文献   

5.
Preparation conditions to obtain a dense electrolyte layer on a micro-tubular electrode support were investigated using wet coating and subsequent co-firing techniques. An anode-supported micro-tubular SOFC with 1.5 mm diameter was successfully fabricated by careful control of the co-sintering process of electrolyte/anode support laminates. The densification of the electrolyte layer deposited on the support surface was greatly affected by the shrinkage of tubular support during the co-sintering process. Support shrinkage above 15% was found to produce a fully densified electrolyte layer on the anode support. In contrast, the use of an anode support with shrinkage below 10% constrained gadolinium-doped ceria (GDC) sintering, resulting in a poorly densified GDC microstructure. Finally, we obtained a micro-tubular cell composed of a dense GDC and a porous (La,Sr)(Co,Fe)O3–GDC multi-layered structure on a NiO–GDC micro-tubular anode support. The cell, with a dense and ≈15 μm thick GDC electrolyte layer, was electrochemically evaluated in a temperature range from 450 to 550 °C. This micro-tubular cell with an electrode length of 6.3 mm showed a power density above 0.1, 0.2 and 0.4 W/cm2 at 450, 500 and 550 °C, respectively, in wet H2 fuel flow.  相似文献   

6.
(La0.8Sr0.2)0.95MnO3?δ (LSM)–Gd0.1Ce0.9O2?δ (gadolinium-doped ceria, GDC) composite cathode material was developed and characterized in terms of chemical stability, sintering behaviour, electrical conductivity, mechanical strength and microstructures to assess its feasibility as cathode support applications in cathode-supported fuel cell configurations. The sintering inhibition effect of LSM, in the presence of GDC, was observed and clearly demonstrated. The mechanical characterization of developed composites revealed that fracture behaviour is directly affected by pore size distribution. The Weibull strength distribution showed that for bimodal pore size distribution, two different fracture rates were present. Furthermore, the contiguity of LSM and GDC grains was calculated with image analysis, and correlation of microstructural features with mechanical and electrical properties was established. Subsequently, an LSM/GDC-based cathode-supported direct carbon fuel cell (DCFC) with Ni/ScSZ (scandia-stabilised zirconia) anode was successfully fabricated via slurry coating and co-firing techniques. The microstructures of electrodes and electrolyte layers were observed to confirm the desired morphology after co-sintering, and a single cell was electrochemically characterized in solid oxide fuel cell (SOFC) and DCFC mode with ambient air as oxidant. The higher values of open-circuit voltage indicated that the electrolyte layer prepared by vacuum slurry coating is dense enough. The corresponding peak power densities at 850 °C were 450 and 225 mW cm?2 in SOFC and DCFC mode, respectively. Electrochemical impedance spectroscopy was carried out to observe electrode polarization and ohmic resistance.  相似文献   

7.
The decrease in the polarization resistance of the anode of solid-oxide fuel cells (SOFCs) due to the formation of an additional NiO/(ZrO2 + 10 mol % Y2O3) (YSZ) functional layer was studied. NiO/YSZ films with different NiO contents were deposited by reactive magnetron sputtering of Ni and Zr–Y targets. The elemental and phase composition of the films was adjusted by regulating oxygen flow rate during the sputtering. The resulting films were studied by scanning electron microscopy and X-ray diffractometry. Comparative tests of planar SOFCs with a NiO/YSZ anode support, NiO/YSZ functional nanostructured anode layer, YSZ electrolyte, and La0.6Sr0.4Co0.2Fe0.8O3/Ce0.9Gd0.1O2 (LSCF/CGO) cathode were performed. It was shown that the formation of a NiO/YSZ functional nanostructured anode leads to a 15–25% increase in the maximum power density of fuel cells in the working temperature range 500–800°C. The NiO/YSZ nanostructured anode layers lead not only to a reduction of the polarization resistance of the anode, but also to the formation of denser electrolyte films during subsequent magnetron sputtering of electrolyte.  相似文献   

8.
化石燃料的使用排放了大量CO2,对气候和环境造成了日益严重的危害.固体氧化物电解池(SOEC)能够利用可再生能源产生的电能将CO2高效转化成CO,降低CO2排放的同时,又能减少化石燃料的使用,近年来受到研究者的广泛关注.相比于低温液相CO2电还原,SOEC高的运行温度保证了其较高的反应速率,即较高的电流密度.典型的SOEC单电池由多孔阴极、致密电解质和多孔阳极以三明治的方式组装而成.CO2分子在阴极得到两个电子解离成CO和一个O2–;生成的O2–通过致密电解质传导至阳极,在阳极失去四个电子发生析氧反应(OER)生成一个O2.相比于两电子的阴极反应,阳极四电子的析氧反应更难进行,可能是整个电极过程的速控步,因此开发高性能的阳极材料有望显著提高SOEC的CO2电还原性能.La0.6Sr0.4Co0.2Fe0.8O3-δ(LSCF)因具有较高的混合离子-电子导电性而被用作SOEC阳极材料,但受LSCF-气体两相界面的限制,其OER性能较低.研究表明,LSCF-掺杂的CeO2-气体所构成的三相界面相比于LSCF-气体两相界面具有更高的电化学反应活性,即OER反应更易在三相界面进行.因此,本文将Gd0.2Ce0.8O1.9(GDC)纳米颗粒浸渍到SOEC LSCF阳极来提高其OER活性,考察了纳米颗粒浸渍量(3,5,10和20 wt%)对SOEC电化学性能的影响.结果表明,SOEC的电化学性能随浸渍量的增加而逐渐升高,当GDC纳米颗粒浸渍量为10 wt%时(10GDC/LSCF),SOEC的电化学性能达到最高,在800 oC和1.6 V的电流密度为0.555 A cm–2,是LSCF阳极SOEC性能的1.32倍.继续增加浸渍量到20 wt%,电化学性能反而开始下降.电化学阻抗谱测试结果表明,GDC纳米颗粒的加入减小了SOEC的极化电阻.对应的弛豫时间分布函数解析结果表明10GDC/LSCF阳极上的OER由四个基元反应构成.电镜和O2-程序升温脱附结果表明,GDC纳米颗粒的加入显著增加了10GDC/LSCF阳极三相界面和表面氧空位的数量以及体相氧的流动性,从而促进了OER四个基元反应的反应速率,降低了这几个过程的极化电阻,因而降低了OER反应的极化电阻,提高了SOEC电还原CO2的电化学性能.  相似文献   

9.
A composite anode of NiFe–MgO (2.5 wt.%)–La0.9Sr0.1Ga0.8Mg0.2O3 (LSGM) (10 wt.%) for solid oxide fuel cells using directly CH4 as fuel was studied. Compared with previously reported NiFe–LSGM (10 wt.%) cermet anode, the NiFe–MgO–LSGM anode exhibited superior power generation performance, stability under CH4 atmosphere at 973 K, and high tolerance against the carbon deposition. These improvements by the additives are explained by the increase in basic property of anode material. The anode activity of NiFe–MgO–LSGM cermet for CH4 fuel is still lower than that for H2 one. However, comparing with that of NiFe–LSGM cermet, anodic overpotential slightly decreased by the addition of MgO, suggesting the improved surface activity.  相似文献   

10.
Remarkable power density was obtained for anode-supported solid oxide fuel cells (SOFCs) based on La0.8Sr0.2Ga0.8Mg0.2O3−δ (LSGM) electrolyte films, fabricated following an original procedure that allowed avoiding undesired reactions between LSGM and electrode materials, especially Ni. Electrophoretic deposition (EPD) was used for the fabrication of 30 μm-thick electrolyte films. Anode supports were made of La0.4Ce0.6O2−x (LDC). The LSGM powder was deposited by EPD on an LDC green tape-cast membrane added with carbon powder, both as pore former and substrate conductivity booster. A subsequent co-firing step at 1490 °C produced dense electrolyte films on porous LDC skeletons. Then, a La0.8Sr0.2Fe0.8Co0.2O3−δ (LSFC) cathode was applied by slurry-coating and calcined at 1100 °C. Finally, the porous LDC layer was impregnated with molten Ni nitrate to obtain, after calcination at 900 °C, a composite NiO–LDC anode. Maximum power densities of 780, 450, 275, 175, and 100 mW/cm2 at 700, 650, 600, 550, and 500 °C, respectively, were obtained using H2 as fuel and air as oxidant, demonstrating the success of the processing strategy. As a comparison, electrolyte-supported SOFCs made of the same materials were tested, showing a maximum power density of 150 mW/cm2 at 700 °C, more than 5 times smaller than the anode-supported counterpart.  相似文献   

11.
Characteristics of fuel cells with supporting Ni-YSZ anode, bilayer YSZ/GDC electrolyte with the thickness of 10 μm, and La2NiO4 + δ cathode are studied. It is shown that when humid (3% water) hydrogen is supplied to the anode and air is supplied to the cathode, the maximum values of cell’s power density are 1.05 and 0.75 W/cm2 at 900 and 800°С, respectively. After the introduction of praseodymium oxide and ceria into the cathode and the anode, respectively, the power density is ca. 1 W/cm2 at 700°С. It is found that the power density of a cell with impregnated electrodes weakly increases with the increase in temperature to ca. 1.4 W/cm2 at 900°С. The analysis of impedance spectra by the distribution of relaxation times shows that such behavior is associated with the gas-diffusion resistance of the SOFC anode. The latter is explained by the low porosity of the anode and the high rate of fuel consumption.  相似文献   

12.
Development of high performance cathodes with low polarization resistance is critical to the success of solid oxide fuel cell (SOFC) development and commercialization. In this paper, (La0.8Sr0.2)0.9MnO3 (LSM)–Gd0.2Ce0.8O1.9(GDC) composite powder (LSM ~70 wt%, GDC ~30 wt%) was prepared through modification of LSM powder by Gd0.2Ce0.8(NO3) x solution impregnation, followed by calcination. The electrode polarization resistance of the LSM–GDC cathode prepared from the composite powder was ~0.60 Ω cm2 at 750 °C, which is ~13 times lower than that of pure LSM cathode (~8.19 Ω cm2 at 750 °C) on YSZ electrolyte substrates. The electrode polarization resistance of the LSM–GDC composite cathode at 700 °C under 500 mA/cm2 was ~0.42 Ω cm2, which is close to that of pure LSM cathode at 850 °C. Gd0.2Ce0.8(NO3) x solution impregnation modification not only inhibits the growth of LSM grains during sintering but also increases the triple-phase-boundary (TPB) area through introducing ionic conducting phase (Gd,Ce)O2-δ, leading to the significant reduction of electrode polarization resistance of LSM cathode.  相似文献   

13.
A cost-effective cell fabrication process was developed for intermediate temperature solid oxide fuel cells (IT-SOFCs). Co-doped ceria Ce0.8Gd0.05Y0.15O1.9 (GYDC) was synthesized by carbonate co-precipitation method. Lithiated NiO was prepared by glycine-nitrate combustion method and adopted as cathode material for IT-SOFCs. Single cell was fabricated by one-step dry-pressing and co-firing anode, anode functional layer (AFL), electrolyte and cathode together at 1200 °C for 4 h. The cell presented decent performance and an overall electrode polarization resistance of 0.54 Ω cm2 has been achieved at 600 °C. These results demonstrate the possibility of using lithiated NiO as cathode material for ceria-based IT-SOFCs and the development of affordable fuel cell devices is encouraged.  相似文献   

14.
The work contains the results of studies of a promising composite material of Sr2Fe1.5Mo0.5O6 + Ce0.8Sm0.2O1.9 for electrodes of symmetrical solid oxide fuel cells. It is shown that conductivity of the composite at 800°C is about 10 and 15 S/cm, for air and humid hydrogen, respectively, and polarization resistance of the electrodes in contact with the electrolyte based on doped lanthanum gallate under the same conditions is about 0.26 and 0.12 Ohm cm2. Tests of a symmetrical fuel cell with a planar design and the supporting gallate electrolyte with the thickness of 300 μm show that the cell can develop the power of about 0.5 W/cm2 at 800°C when air is supplied to the cathode and humid hydrogen is supplied to the anode. Analysis of polarization losses shows that the polarization of the oxygen electrode considerably exceeds the polarization of the anode.  相似文献   

15.
Herein, the Sr2Fe1.5Mo0.5O6 (SFM) precursor solution is infiltrated into a tri-layered “porous La0.9Sr0.1Ga0.8Mg0.2O3 (LSGM)/dense LSGM/porous LSGM” skeleton to form both SFM/LSGM symmetrical fuel cells and functional fuel cells by adopting an ultra-fast and time-saving procedure. The heating/cooling rate when fabricating is fixed at 200 °C/min. Thanks to the unique cell structure with high thermal shock resistance and matched thermal expansion coefficients (TEC) between SFM and LSGM, no SFM/LSGM interfacial detachment is detected. The polarization resistances (Rp) of SFM/LSGM composite cathode and anode at 650 °C are 0.27 Ω·cm2 and 0.235 Ω·cm2, respectively. These values are even smaller than those of the cells fabricated with traditional method. From scanning electron microscope (SEM), a more homogenous distribution of SFM is identified in the ultra-fast fabricated SFM/LSGM composite, therefore leading to the enhanced performance. This study also strengthens the evidence that SFM can be used as high performance symmetrical electrode material both running in H2 and CH4. When using H2 as fuel, the maximum power density of “SFM-LSGM/LSGM/LSGM-SFM” functional fuel cell at 700 °C is 880 mW cm 2. By using CH4 as fuel, the maximum power densities at 850 and 900 °C are 146 and 306 mW cm 2, respectively.  相似文献   

16.
A green BaZr0.1Ce0.7Y0.2O3−δ (BZCY) electrolyte layer was deposited on porous anode substrate (BZCY:NiO = 35:65, in weight ratio) by a suspension spray. In this process, the suspension was prepared by directly ball-milling the mixed BaCO3, CeO2, ZrO2 and Y2O3 powders in ethanol for 24 h. Then the bi-layers were co-sintered at 1400 °C for 5 h in air to obtain dense and uniform electrolyte membrane in the thickness of 10 μm. With Nd0.7Sr0.3MnO3−δ cathode, a fuel cell was assembled. It was tested from 600 °C to 700 °C using humid hydrogen as fuel and air as oxidant. The cell at 700 °C exhibited 1.02 V for open circuit voltage (OCV), 450 mW/cm2 for peak output and 0.18 Ω cm2 for electrode polarizations under open circuit conditions, respectively. The results indicate that it is feasible to fabricate thin electrolyte membrane for solid oxide fuel cells (SOFCs) by this simple, cost-effective and efficient technique.  相似文献   

17.
Transition metal oxide doped lanthanum gallates, La0.9Sr0.1Ga0.8M0.2O3 (where M=Co, Mn, Cr, Fe, or V), are studied as mixed ionic-electronic conductors (MIECs) for electrode applications. The electrochemical properties of these materials in air and in H2 are characterized using impedance spectroscopy, open cell voltage measurement, and gas permeation measurement. Three single cells based on La0.9Sr0.1Ga0.8 Mg0.2O3 (LSGM) electrolyte (1.13 to 1.65 mm thick) but with different electrode materials are studied under identical conditions to characterize the effectiveness of the lanthanum gallate-based MIECs for electrode applications. At 800 °C, a single cell using La0.9Sr0.1- Ga0.8Co0.2O3 as the cathode and La0.9Sr0.1Ga0.8Mn0.2O3 as the anode shows a maximum power density of 88 mW/cm2, which is better than that of a cell using Pt as both electrodes (20 mW/cm2) and that of a cell using La0.6Sr0.4CoO3 (LSC) as the cathode and CeO2-Ni as the anode (61 mW/cm2) under identical conditions. The performance of LSGM-based fuel cells with MIEC electrodes may be further improved by reducing the electrolyte thickness and by optimizing the microstructures of the electrodes through processing. Received: 9 January 1998 / Accepted: 1 May 1998  相似文献   

18.
The ESB/GDC bilayer electrolyte concept has been proved to improve open circuit voltage and reduce the effective area specific resistance of SOFCs utilizing a conventional single-layer GDC electrolyte. However, high performance from such bilayer cells had not yet been demonstrated. The main obstacles toward this end have been fabrication of anode-supported thin-film electrolytes and the reactivity of ESB with conventional cathodes. Recently, an ESB-compatible low area specific resistance cathode was developed: microstructurally optimized Bi2Ru2O7-ESB composites. In addition, we recently developed a novel anode functional layer which can significantly enhance the performance of SOFC utilizing GDC electrolytes. This study combines these recent achievements in SOFC studies and shows that exceptionally high performance of SOFC is possible using ESB/GDC bilayer electrolytes and Bi2Ru2O7-ESB composite cathodes. The result confirms that the bilayer electrolyte and the Bi2Ru2O7-ESB cathode can increase the open circuit potential and reduce the total area specific resistance. The maximum power density of the bilayered SOFC was improved to 1.95 W cm?2 with 0.079 Ω cm2 total cell area specific resistance at 650 °C. This is the highest power yet achieved in the IT range and we believe redefines the expectation level for maximum power under IT-SOFC operating conditions.  相似文献   

19.
A complex study of thermal, conducting, and electrocatalytic properties of cuprates La1.8?xPrxSr0.2CuO4–δ (х = 0.2; 0.4) with the K2NiF4 structure is carried out in order to assess their prospects as the cathode materials for solid-oxide fuel cells. The thermal analysis reveals stability of samples heated up to 950°С in air. The conductivity of cuprates measured in the temperature range of 100–900°С and the partial oxygen pressure from 10–3 to 1 atm is of the metallic nature and varies from 70 to 40 S/cm in the temperature interval of 500–900°С in air. The studies of chemical stability of cuprates with respect to solid electrolytes demonstrate the absence of their chemical interaction with Ce0.9Gd0.1O1.95 (GDC) at 900°С and with La0.8Sr0.2Ga0.85Mg0.15O3–δ (LSGM) at 1000°C after 25 h annealing. For La1.6Pr0.2Sr0.2CuO4–δ electrodes deposited on the surface of GDC or LSGM solid electrolytes, the studies of electrocatalytic activity in the oxygen reduction reaction demonstrate that the smallest polarization resistance is typical of electrodes deposited on the GDC surface.  相似文献   

20.
La0.6Sr1.4MnO4 (LSMO4) layered perovskite with K2NiF4 structure was prepared and evaluated as anode material for La0.8Sr0.2Ga0.83Mg0.17O3 − δ (LSGM) electrolyte supported intermediate temperature solid oxide fuel cells (IT-SOFCs). X-ray diffraction results show that LSMO4 is redox stability. Thermal expansion coefficient of LSMO4 is close to that of LSGM electrolyte. By adopting LSMO4 as anode and La0.6Sr0.4Co0.8Fe0.2O3 (LSCF) as cathode, maxium power densities of 146.6, 110.9 mW cm− 2 with H2 fuel at 850, 800 °C and 47.3 mW cm− 2 with CH4 fuel at 800 °C were obtained, respectively. Further, the cell demonstrated a reasonably stable performance under 180 mA cm− 2 for over 40 h with H2 fuel at 800 °C.  相似文献   

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