共查询到20条相似文献,搜索用时 62 毫秒
1.
Jung Hyun Kim 《Applied Surface Science》2011,258(1):350-355
The chemical states of the surface of (Ln0.5Sr0.5)CoO3?δ (Ln (lanthanides) = Pr, Nd and Sm) used for cathode materials of intermediate temperature operating solid oxide fuel cells (IT-SOFCs) were investigated by X-ray photoelectron spectroscopy (XPS). Oxygen peaks comprised of lower binding energy (LBE) and higher binding energy (HBE) peaks from (Ln0.5Sr0.5)CoO3?δ and Pr0.3Sr0.7CoO3?δ (PSC37) showed that some merged oxygen peak behavior is a function of the Sr and lanthanide concentrations. By investigating the oxygen peaks, it was determined that more oxygen vacancies were generated on the surface of the cathodes when the lanthanides and Sr were substituted into perovskite oxides. When comparing the binding energies (BEs) of PSC37 with Pr0.5Sr0.5CoO3?δ (PSC55), the LBE and HBE of the Sr peaks both increased when Sr was substituted at the A-site of a perovskite. Surface analysis of the Co peak on the surface of the cathode materials showed that the Co exists mainly as Co3+ and partially oxidized to Co4+ on the cathode materials. The partial existence of Co4+ can provide some polaron hopping providing electronic conduction for the solid oxide fuel cell. 相似文献
2.
S. S. Pawar K. P. Shinde R. S. Joshi R. S. Kalubarme A. G. Bhosale S. H. Pawar 《Ionics》2010,16(7):649-654
Nano-crystalline films of Sm0.5Sr0.5CoO3 (SSC) have been formed on CeO2 substrates by spraying stoichiometric aqueous solution containing Sm, Sr, and Co ions. Effect of polyvinyl alcohol (PVA)
addition as a complexing agent in spray solution on stoichiometry, crystallite size, morphology, and transport properties
of film are studied. The results showed that the SSC cathode had maximum crystallite size for 40% PVA addition. Electrical
performance of film decreases with decrease in the particle size, while the electronic to ionic predominance transition temperature
decreases with decreasing particle size. These films are studied for their potential application as a cathodic material in
developing intermediate temperature solid oxide fuel cells. 相似文献
3.
Yttria stabilized zirconia (YSZ) is the most commonly used electrolyte material in solid oxide fuel cells (SOFC’s). However,
doped lanthanum gallate is an interesting alternative for use at intermediate temperatures (typically 600 – 750 °C). Commercially
available La0.8Sr0.2Ga0.8Mg0.2O2.8 (LSGM) powder was mixed with a polymer-based binder system and extruded into two different size tubes. After sintering, the
electrolyte tubes were approximately (a) 6 mm outside diameter, 0.55 mm wall thickness and 100–200 mm long and (b) 4 mm outside
diameter, 0.22 mm wall thickness and 50–100 mm long. The tubes were then fabricated into SOFC’s, using a range of anode and
cathode morphologies. The electrical performance of the cells was then tested using hydrogen as a fuel. A repeatable and constant
power of over 2.5 W per cell was obtained at 800 °C and 0.7 V. The maximum power density of the tubular fuel cell with La0.6Sr0.4CoO3 cathode, Ce0.8Sm0.2O1.9 interlayer and a Ni anode was 482 mW/cm2. This paper will present the fabrication procedure and parameters, fuel cell performance test results, and the effect of
electrode morphologies on the performance of the fuel cells.
Paper presented at the 9th EuroConference on Ionics, Ixia, Rhodes, Greece, Sept. 15 – 21, 2002. 相似文献
4.
《Solid State Ionics》2006,177(19-25):1949-1953
Partial electronic and oxide ionic conduction in LaGaO3 doped with Sr and Mg, Co for Ga site was studied with the ion blocking method. It was found that doping small amount of Co into Ga site is effective for elevating the oxide ion conductivity. However, it is seen that the partial electronic conduction monotonically increases with increasing Co amount and PO2 at p–n transition was shifted to lower value. Even at X = 0.1, the oxide ion conductivity in LSGMC is still dominant. Calculation on the theoretical leakage of electrolyte of solid oxide fuel cells suggests that the highest efficiency of the electrolyte was achieved around 100 μm in thickness for La0.8Sr0.2Ga0.8Mg0.15Co0.05O3 (LSGMC). Preparation of LSGMC film on Ni–Sm0.2Ce0.8O2 porous anode was studied with the colloidal spray method. In order to prevent the reaction between substrate and film, La doped CeO2 was used for the interlayer film. In accordance with the theoretical calculation, open circuit potential of the cell using LSGMC film electrolyte with 40 μm thickness becomes much smaller than the theoretical value. However, fairly large maximum power density (0.21 W/cm2) can be achieved at 873 K and even at 773 K, the maximum power density of the cell as high as 0.12 W/cm2 was exhibited on the SOFC using 40 μm thickness LSGMC electrolyte. 相似文献
5.
《Solid State Ionics》2006,177(19-25):2053-2057
La(Sr)Ga(Fe,Mg)O3 exhibited the high oxide ion conductivity and the electrical power generating property of SOFC single cell using La0.7Sr0.3Ga0.7Fe0.2Mg0.1O3-δ (LSGFM) electrolyte was investigated in this study. The transport number of oxide ion is almost 0.8 in LSGFM and so open circuit potential (OCV) is as low as 0.8 V. OCV was strongly affected by anode materials and the highest OCV was achieved on Ni–Fe bimetallic anode. The extremely high power density was achieved by using LSGFM for electrolyte of SOFC. The maximum power densities of the cells can be elevated by coating with oxide ion conductor film at anode side. The maximum power density increased in the following order for coating film: LSGM > SDC > YSZ. The maximum power density of 197 and 100 mW/cm2 can be achieved at 873 and 773 K, respectively, when LSGM film deposited on the anode side of LSGFM. Therefore, LSGFM can be used as electrolyte of SOFC operating at intermediate temperature. 相似文献
6.
A fabrication method that does not use lithography or etching processes for thick-film based micro-SOFCs (Solid Oxide Fuel Cells) was described and discussed. In this study, a new type of micro-SOFC was fabricated using a free-standing thick-film electrolyte with ~ 20 μm thickness. This structure has the advantages of both electrolyte-support and electrode-support type SOFCs. Generally, the electrolyte should be thicker than e.g., ~ 150 μm since a thinner electrolyte easily cracks in a self-supporting mode during the fabrication procedure. Thus, a new mounting method was developed in order to use a thin-electrolyte film. In this study, a ~ 20 μm-thick GDC (Gd-doped ceria) electrolyte film was successfully mounted on a ~ 400 μm-thick GDC ring by sintering these two pieces together. Ni-GDC and Sm0.5Sr0.5CoO3 were brush painted as an anode and a cathode, respectively. With this new configuration, it was possible to construct an electrolyte-supported SOFC using a thick-film ceria-based electrolyte and measure the power density. The open-circuit voltage (OCV) of the cell in 97%H2 + 3%H2O/air was ~ 0.87 V and the maximum power density was ~ 270 mW/cm2 at 600 °C. The result shows that the high performance is achievable for the micro-SOFCs using a thick-film ceria-electrolyte operating at 600 °C. 相似文献
7.
Songlin Wang 《Ionics》2012,18(8):777-780
A cobalt-free Ba0.5Sr0.5Fe0.9Nb0.1O3??? (BSFNb) perovskite-type oxide was investigated as the cathode material for intermediate-temperature solid oxide fuel cells (IT-SOFCs) with Sm0.2Ce0.8O1.9 (SDC) electrolyte. XRD results showed that BSFNb cathode was chemically compatible with the electrolyte SDC up to 1,000?°C. The maximum output of anode-supported thin-film SOFC reached 503?mW?cm?2 at 650?°C when employing humidified H2 as fuel and static air as oxidizer. The electrode polarization resistance was low as 0.078????cm2 at 650?°C, and the activation energy of the electrode polarization resistance was 129.72?kJ?mol?1. The experimental results indicated that the cobalt-free BSFNb was a promising cathode candidate for IT-SOFCs. 相似文献
8.
I. C. Fullarton J. -P. Jacobs H. E. van Benthem J. A. Kilner H. H. Brongersma P. J. Scanlon B. C. H. Steele 《Ionics》1995,1(1):51-58
Dense samples of the perovskite Sm1−xSrxCoO3 (where x=0, 0.2, 0.4, 0.5 and 0.6) have been prepared. The samples were18O/16O isotopically exchanged at a variety of temperatures between 500°C and 900°C. Subsequent analysis of the diffusion profile
using Secondary Ion Mass Spectrometry (SIMS) allowed the oxygen self-diffusion coefficient, D*, and surface exchange co-efficient,
k, to be determined. From the temperature dependence of these parameters the activation energies for both processes were evaluated.
The surface coverage of samarium, cobalt and oxygen in SmCoO3 was determined from calibration samples using Low Energy Ion Scattering (LEIS). LEIS was used to determine the effect of
strontium doping on the surface composition and the18O-concentration at the surface of a number of the18O-exchanged samples.
Paper presented at the 1st Euroconference on Solid State Ionics, Zakynthos, Greece, 11 – 18 Sept. 1994. 相似文献
9.
Polycrystalline perovskite cobalt oxide Eu0.5Sr0.5CoO3 was prepared by the conventional solid-state reaction method. X-ray powder patterns indicated the prepared samples are pure, cubic perovskite structure (Pm3?m), and with no evidence of any secondary phases. The dc magnetization and ac susceptibility measurements were carried out to investigate the magnetic properties of the sample, and which indicated that cluster-glasses properties are suppressed with the increasing of the coercive field. We denied the possibility of spin-glasses and the existence of the Hopkinson effect in Eu0.5Sr0.5CoO3 through the temperature-dependent ac susceptibility measurements, and explained the magnetic behavior of Eu0.5Sr0.5CoO3 with the competition between magnetic anisotropy and the external magnetic field. 相似文献
10.
Seung-Wook BaekJihoon Jeong Yu-Mi KimJung Hyun Kim Sungmin ShinJoongmyeon Bae 《Solid State Ionics》2011,192(1):387-393
Materials containing barium (Ba), such as SmBa0.5Sr0.5Co2O5-d/Ce0.9Gd0.1O1.9 (SBSC50) and Ba0.5Sr0.5Co0.8Fe0.2O3-d (BSCF), are considered for use as an in-situ cathode in metal-supported solid oxide fuel cells (SOFCs). The electrochemical properties and sintering behavior of these materials are investigated in terms of area specific resistances (ASRs), I-V-P characteristics and microstructure. The properties of in-situ cathodes comprised of SBSC50 and BSCF are compared with those of conventional cathodes, such as La0.8Sr0.2MnO3-d (LSM), La0.8Sr0.2FeO3-d (LSF), La0.6Sr0.4Co0.2Fe0.8O3-d (LSCF) and Sm0.5Sr0.5CoO3-d/Ce0.8Sm0.2O1.9 (SSC40). Impedance spectroscopy analysis using Nyquist and Bode plots and microstructure analysis is conducted to understand the reason behind electrochemical performance differences between in-situ cathodes and sintered cathodes. From this analysis, we are also able to verify the electrochemical behavior of well-defined in-situ cathodes. SBSC50 and BSCF are the incorporated in our metal-supported cells without the use of any additional sintering process. The metal-supported cells are successfully fabricated using a high temperature sinter-joining process and we fail to detect any defects or deformation after fabrication. At an operating temperature of 800 °C, metal-supported cells with SBSC50 and BSCF cathodes exhibit maximum power densities of 0.50 Wcm-2 and 0.65 Wcm-2, respectively. 相似文献
11.
Ni-containing anode is currently used with many electrolytes of solid oxide fuel cells (SOFCs). However, Ni is easily oxidized and deteriorates the LaGaO3-based electrolyte. A La-doped SrTiO3 (LST, La0.2Sr0.8TiO3) is a candidate as an anode material to solve the Ni poisoning problem in LaGaO3-based SOFC. In this study, a single-phase LST and an LST-Gd0.2Ce0.8O2 ? δ (GDC) composite were tested as the possible anodes on La0.9Sr0.1Ga0.8Mg0.2O3 ? δ (LSGM) electrolyte. In order to further improve the anodic performance, Ni was impregnated into the LST-GDC composite anode. The performance was examined from 600 °C to 800 °C by measuring impedance of the electrolyte-supported, symmetric (anode/electrolyte/anode) cells. A polarization resistance (Rp) of LST-GDC anode was much reduced from that of LST anode. When Ni was impregnated into LST-GDC composite, the Rp value was further reduced to ~ 10% of the single-phase LST anode, and it was 1 Ωcm2 at 800 °C in 97% H2 + 3% H2O atmosphere. A single cell with Ni-impregnated LST-GDC as an anode, Ba0.5Sr0.5Co0.8Fe0.2O3 ? δ (BSCF) as a cathode and LSGM as an electrolyte exhibited the maximum power density of 275 mW/cm2 at 800 °C, increased from ~ 60 mW/cm2 for the cell using the LST-GDC as an anode. Thus, LST-GDC composite is promising as a component of anode. 相似文献
12.
Doping transition metal cation is known to enhance the electronic conduction of solid electrolytes, however, the ionic conduction
can also be improved by those dopants. In this investigation, the oxide ion conductivity of LaGaO3 based oxide doped with transition metal cations such as Fe, Co, Ni, Mn, and Cu for the Ga site was studied. It was found
that doping Co or Fe is effective for enhancing the oxide ion conductivity. The improved oxide ion conductivity may be induced
by the improved mobility of oxide ion. Among examined transition metal cations, cobalt is the most adequate cation as a dopant
for the Ga site of LSGM. Considering the conductivity and the transport number, the optimized composition is found to be La0.8Sr0.2Ga0.8Mg0.115Co0.085O3. In this work, application of Co2+ doped LSGM as the electrolyte of internally reformed fuel cells was also investigated. Improvement in oxide ion conductivity
is effective for enhancing the power generation characteristics.
Paper presented at the 4th Euroconference on Solid State Ionics, Renvyle, Galway, Ireland, Sept. 13–19, 1997 相似文献
13.
《Journal of Physics and Chemistry of Solids》2007,68(5-6):758-764
In order to discuss oxide ion conduction mechanism for LaGaO3-based perovskite compounds, doping effects were investigated using two kinds of solid solutions whose oxygen vacancy concentrations are the same: one is La0.9Sr0.1Ga0.9Mg0.1O2.9 with A-site and B-site substitutions and the other is LaGa0.8Mg0.2O2.9 with only B-site substitution. Conductivity measurements showed that La0.9Sr0.1Ga0.9Mg0.1O2.9 had a circumstance whereby oxide ion could more easily diffuse in the perovskite structure than in LaGa0.8Mg0.2O2.9. Structural analyses using neutron diffraction found out the following three differences: the first finding was that the saddle point formed by two A-site cations and one B-site cation in La0.9Sr0.1Ga0.9Mg0.1O2.9 was larger than that in LaGa0.8Mg0.2O2.9 due to larger displacements of A-site and B-site cations; the second was that the doubly doping with Sr and Mg was more effective for reduction of GaO6 octahedral tilt angles than the doping with Mg; the last was that La0.9Sr0.1Ga0.9Mg0.1O2.9 had larger oxygen displacement than LaGa0.8Mg0.2O2.9. It was considered that these structurally related parameters dominated the high oxide ion conduction in LaGaO3-based perovskite compounds. 相似文献
14.
This paper reports on the electrochemical properties and chemical stability of a recently developed Ca2+ and Sm3+-doped oxide ion conducting electrolyte, Ce0.85Ca0.05Sm0.1O1.9 (CCS), employed in an intermediate temperature solid oxide fuel cell (IT-SOFC) using conventional Sm0.5Sr0.5CoO3 (SSC) and La0.8Sr0.2MnO3 (LSM) cathodes in air at elevated temperatures. The materials were prepared by conventional solid-state reactions using their
corresponding metal oxides and salts in the temperature range of 1,200–1,450 °C in air. Powder X-ray diffraction (PXRD) and
impedance spectroscopy were employed for phase formation, chemical compatibility, and electrochemical characterization. PXRD
studies on 1:1 weight ratio of heat-treated (1,000 °C for 3 days) mixtures of SSC or LSM and CCS revealed the presence of
fluorite-type and perovskite-like phases. The area-specific resistance (ASR) value in air was lower for SSC cathodes (4.3–0.15 Ω
cm2) compared to those of LSM (407–11 Ω cm2) over the investigated temperature range of 600–800 °C. As expected, a significant increase in ASR was observed in Ar as
compared to air. 相似文献
15.
Three solid oxide cells have been investigated after long-term high temperature electrolysis to explain the phenomena of accelerated degradation. These cells contain a Ni-YSZ cermet (Ni-yttria-stabilised-zirconia) as hydrogen electrode (cathode), yttria-stabilised-zirconia (YSZ) as electrolyte, Ce0.8Gd0.2O1.9 (CGO) as diffusion barrier layer and La0.58Sr0.4Co0.2Fe0.8O3 (LSCF) as oxygen electrode (anode). Cell 1, cell 2 and cell 3 were tested continuously at about 770 °C, with a current density of ?1 A cm?2 and 80 % H2O of absolute humidity for 9000, 1770 and 1460 h, respectively. It was found that in cell 1, the degradation rate was about 2.2 % per 1000 h, in cell 2 the degradation rate increased to 3.4 % per 1000 h and in cell 3 the degradation rate was 2.6 % per 1000 h. The mode of cell degradation was also investigated as a function of the cell fabrication in the four layers system (anode/diffusion barrier layer/electrolyte/cathode). An intergranular fractured surface along the grain boundaries of the electrolyte, and the formation of porous structures throughout the thickness of the electrolyte were observed in cell 1. LSCF, as the oxygen electrode, showed compositional fluctuations with a changed perovskite composition and formation of cobalt oxide. This phenomenon reduces the electrical conductivity and, probably, also the catalytic properties. The hydrogen electrode did not show major changes in all the three cells tested. Cells 2 and 3 showed similar features as observed for cell 1, except the fact that they retained the electrolyte structure without intergranular fracture and formation of porosity after continuous testing for long duration. 相似文献
16.
The sensing characteristics of an amperometric NOx sensor with yttria-stabilized zirconia and a La-based perovskite-type oxide
sensing electrode were examined. La1-xSrxMO3 (M = Co, Mn, x = 0, 0.2, 0.4, 0.6) were synthesized using the spray pyrolysis method. The NO2 response of a sensor fabricated with La1-xSrxMnO3 increased with increasing amount of Sr, and the trend was in contrast to that of the sensors fabricated with La1-xSrxCoO3. LaSr0.2MnO3 was determined to be the most appropriate material for the sensor in terms of a high NO2 response and low O2 current. In order to discuss the effects of Sr addition to La-based perovskite oxides for the sensor, NO adsorption and desorption
properties of oxides and the relationship between the oxidation number of the B-site cation and Sr substitution were examined
using temperature-programmed desorption and X-ray photoelectron spectroscopy, respectively. 相似文献
17.
A reduction in the operating temperature in SOFC can decrease materials degradation for long term operation. The efficiency of energy conversion and durability of performance mainly depend on the electro catalytic activity of the cathode and its thermo-chemical compatibility with the oxide ion conducting solid electrolyte. In this work, La0.65Sr0.35CoO3-δ (LSC 6535), a mixed conducting stable perovskite oxide prepared by glycine nitrate route is systematically characterized. Circular pellets were fabricated and subjected to sintering at different temperatures ranging from 1073–1773 K. the sintering behaviour of LSC and LSC-YZ composite were investigated to obtain information on the densification, shrinkage in volume after heat treatment. The thermo-chemical compatibility of this cathode material with YZ is also brought out. Complex impedance spectroscopy was used for determining the conductivity and electrical behaviour. The component diffusion coefficient and mobility of ions were calculated from conductivity values. A brief discussion is made on its suitability for application as electro catalytic materials under ITSOFC operating conditions. 相似文献
18.
Porous Ni-YSZ (YSZ—yttria-stabilized zirconia) films were fabricated by reactive co-sputtering of a Ni and a Zr-Y target, followed by sequentially annealing in air at 900 °C and in vacuum at 800 °C. The Ni-YSZ films comprised small grains and pores that were tens of nanometers in size. The porous Ni-YSZ films were used as an anode on one side of a YSZ electrolyte disc and a La0.7Sr0.3MnO3 thick film was used as a cathode on the other side of the disc to form solid oxide fuel cells (SOFCs). The voltage-current curves of the SOFCs with single- and a triple-layered porous anodes were measured in a single-chamber configuration, in a mixture of CH4 and air (CH4:O2 volume ratio=2:1). The maximum power density of the SOFC using the single-layered porous Ni-YSZ thin films as the anode was 0.38 mW cm−2, which was lower than that of 0.76 mW cm−2, obtained using a screen-printed Ni-YSZ thick anode. The maximum power density of the SOFC with a thin anode was increased, but varied between 0.6 and 1.14 mW cm−2 when a triple-layered porous Ni-YSZ anode was used. 相似文献
19.
Anode supported thick film ceria electrolyte unit cells were fabricated using a colloidal dip coating method for IT-SOFCs.
Pre-sintering temperature of the anode substrate and the final sintering temperature were found to be the primary parameters
determining the density of the film. With Ni-Ce0.89Gd0.11 O2–δ cermet anode, La0.6Sr0.4Co0.2Fe0.8O3 cathode and 15 μm Ce0.89Gd0.11 O2–δ electrolyte, the cells were tested in a fuel cell configuration with air at the cathode and moist H2 at the anode. At 650 °C, the cell indicated a maximum power density of ∼0.27 W/cm2 at a current density of 0.62 A/cm2. Cell performance was compared with oxygen at the cathode and the cell indicated a maximum power density of ∼0.50 W/cm2 at 1.14 A/cm2, 650 °C. Activation energy for the area specific resistance (ASR) of the cell suggests that with air at cathode, the cell
performance was limited by gaseous diffusion at cathode and with oxygen at cathode, by oxygen ion transport across the electrolyte. 相似文献
20.
采用有机凝胶法结合高温烧结制备了Sm0.9Sr0.1Al1-xCoxO3-δ (SSAC,x = 0.2,0.4,0.5,0.6) 系列钙钛矿结构混合导电陶瓷,并详细讨论了烧结温度和Co掺杂量对其晶体结构、相组成和电性能的影响.X射线衍射结果显示,过高的烧结温度或Co掺杂量都会导致杂相Sm(Sr)CoO3生成,Co在该体系的固溶限位于50mol%—60mol%之间,Co对Al的部分取代使晶格体积增大.电性能测量结果表明,SSAC陶瓷的电导率主要取决于p型电导,其导电行为符合小极化子跳跃导电机制;随着烧结温度的升高,材料的电导率逐渐增大;在固溶限内随Co含量的增加,SSAC陶瓷的电导率增大,表观活化能减小;1200 ℃烧结10 h制得的单相Sm0.9Sr0.1Al0.5Co0.5O3-δ陶瓷体在800℃的电导率达63.4 S/cm,表观活化能为0.14eV.具有良好电性能的SSAC导电陶瓷有望应用于高温电化学领域.
关键词:
导电陶瓷
3')" href="#">Sr和Co掺杂的SmAlO3
有机凝胶法
电性能 相似文献