共查询到20条相似文献,搜索用时 31 毫秒
1.
Chromium-deficient Nd0.75Ca0.25Cr1−xO3−δ (0.02 ≤ x ≤ 0.06) oxides are synthesized and assessed as a novel ceramic interconnect for solid oxide fuel cells (SOFCs). At room temperature, all the samples present single perovskite phase after sintering at 1600 °C for 10 h in air. Cr-deficiency significantly improves the electrical conductivity of Nd0.75Ca0.25Cr1−xO3−δ oxides. No structural transformation occurs in the Nd0.75Ca0.25Cr1−xO3−δ oxides in the temperature range studied. Among all the samples, the Nd0.75Ca0.25Cr0.98O3−δ sample with a relative density of 96.3% exhibits the best electrical conductivity of 39.0 and 1.6 S cm−1 at 850 °C in air and hydrogen, respectively. The thermal expansion coefficient of Nd0.75Ca0.25Cr0.98O3−δ sample is 9.29 × 10−6 K−1 in the temperature range from 30 to 1000 °C in air, which is close to that of 8 mol% yttria stabilized zirconia electrolyte (10.3 × 10−6 K−1) and other cell components. The results indicate that Nd0.75Ca0.25Cr0.98O3−δ is a potential interconnect material for SOFCs. 相似文献
2.
Sang Bu Ha Pyeong-Seok Cho Yoon Ho Cho Dokyol Lee Jong-Heun Lee 《Journal of power sources》2010,195(1):124-129
A range of La0.75Sr0.25Cr0.5Mn0.5O3−δ (LSCM) powders is prepared by the carbonate coprecipitation method for use as anodes in solid oxide fuel cells. The supersaturation ratio (R = [(NH4)2CO3]/([La3+] + [Sr2+] + [Cr3+] + [Mn2+])) during the coprecipitation determines the relative compositions of La, Sr, Cr, and Mn. The composition of the precursor approaches the stoichiometric one at the supersaturation range of 4 ≤ R ≤ 12.5, whereas Sr and Mn components are deficient at R < 4 and excessive at R = 25. The fine and phase-pure LSCM powders are prepared by heat treatment at very low temperature (1000 °C) at R = 7.5 and 12.5. By contrast, the solid-state reaction requires a higher heat-treatment temperature (1400 °C). The catalytic activity of the LSCM electrodes is enhanced by using carbonate-derived powders to manipulate the electrode microstructures. 相似文献
3.
A series of cobalt-free and low cost BaCexFe1−xO3−δ (x = 0.15, 0.50, 0.85) materials are successful synthesized and used as the cathode materials for proton-conducting solid oxide fuel cells (SOFCs). The single cell, consisting of a BaZr0.1Ce0.7Y0.2O3−δ (BZCY7)-NiO anode substrate, a BZCY7 anode functional layer, a BZCY7 electrolyte membrane and a BaCexFe1−xO3−δ cathode layer, is assembled and tested from 600 to 700 °C with humidified hydrogen (3% H2O) as the fuel and the static air as the oxidant. Within all the cathode materials above, the cathode BaCe0.5Fe0.5O3−δ shows the highest cell performance which could obtain an open-circuit potential of 0.99 V and a maximum power density of 395 mW cm−2 at 700 °C. The results indicate that the Fe-doped barium cerates can be promising cathodes for proton-conducting SOFCs. 相似文献
4.
Xiao-Feng Ye S.R. Wang Z.R. Wang Q. Hu X.F. Sun T.L. Wen Z.Y. Wen 《Journal of power sources》2008,183(2):512-517
The perovskite system La1−xSrxCr1−yMyO3−δ (M, Mn, Fe and V) has recently attracted much attention as a candidate material for the fabrication of solid oxide fuel cells (SOFCs) due to its stability in both H2 and CH4 atmospheres at temperatures up to 1000 °C. In this paper, we report the synthesis of La0.75Sr0.25Cr0.5Mn0.5O3 (LSCM) by solid-state reaction and its employment as an alternative anode material for anode-supported SOFCs. Because LSCM shows a greatly decreased electronic conductivity in a reducing atmosphere compared to that in air, we have fabricated Cu-LSCM-ScSZ (scandia-stabilized zirconia) composite anodes by tape-casting and a wet-impregnation method. Additionally, a composite structure (support anode, functional anode and electrolyte) structure with a layer of Cu-LSCM-YSZ (yttria-stabilized zirconia) on the supported anode surface has been manufactured by tape-casting and screen-printing. Single cells with these two kinds of anodes have been fabricated, and their performance characteristics using hydrogen and ethanol have been measured. In the operation period, no obvious carbon deposition was observed when these cells were operated on ethanol. These results demonstrate the stability of LSCM in an ethanol atmosphere and its potential utilization in anode-supported SOFCs. 相似文献
5.
Xingbao Zhu Zhe Lü Bo Wei Kongfa Chen Mingliang Liu Xiqiang Huang Wenhui Su 《Journal of power sources》2009,190(2):326-330
The optimization of electrodes for solid oxide fuel cells (SOFCs) has been achieved via a wet impregnation method. Pure La0.75Sr0.25Cr0.5Mn0.5O3−δ (LSCrM) anodes are modified using Ni(NO3)2 and/or Ce(NO3)3/(Sm,Ce)(NO3)x solution. Several yttria-stabilized zirconia (YSZ) electrolyte-supported fuel cells are tested to clarify the contribution of Ni and/or CeO2 to the cell performance. For the cell using pure-LSCrM anodes, the maximum power density (Pmax) at 850 °C is 198 mW cm−2 when dry H2 and air are used as the fuel and oxidant, respectively. When H2 is changed to CH4, the value of Pmax is 32 mW cm−2. After 8.9 wt.% Ni and 5.8 wt.% CeO2 are introduced into the LSCrM anode, the cell exhibits increased values of Pmax 432, 681, 948 and 1135 mW cm−2 at 700, 750, 800 and 850 °C, respectively, with dry H2 as fuel and air as oxidant. When O2 at 50 mL min−1 is used as the oxidant, the value of Pmax increases to 1450 mW cm−2 at 850 °C. When dry CH4 is used as fuel and air as oxidant, the values of Pmax reach 95, 197, 421 and 645 mW cm−2 at 750, 800, 850 and 900 °C, respectively. The introduction of Ni greatly improves the performance of the LSCrM anode but does not cause any carbon deposit. 相似文献
6.
Cathode materials consisting of Pr1−xSrxCo0.8Fe0.2O3−δ (x = 0.2–0.6) were prepared by the sol–gel process for intermediate-temperature solid oxide fuel cells (IT-SOFCs). The samples had an orthorhombic perovskite structure. The electrical conductivities were all higher than 279 S cm−1. The highest conductivity, 1040 S cm−1, was found at 300 °C for the composition x = 0.4. Symmetrical cathodes made of Pr0.6Sr0.4Co0.8Fe0.2O3−δ (PSCF)–Ce0.85Gd0.15O1.925 (50:50 by weight) composite powders were screen-printed on GDC electrolyte pellets. The area specific resistance value for the PSCF–GDC cathode was as low as 0.046 Ω cm2 at 800 °C. The maximum power densities of a cell using the PSCF–GDC cathode were 520 mW cm−2, 435 mW cm−2 and 303 mW cm−2 at 800 °C, 750 °C and 700 °C, respectively. 相似文献
7.
Hongxia Gu Yao Zheng Ran Ran Zongping Shao Wanqin Jin Nanping Xu Jeongmin Ahn 《Journal of power sources》2008,183(2):471-478
Perovskite-type La0.8Sr0.2ScyMn1−yO3−δ oxides (LSSMy, y = 0.0–0.2) were synthesized and investigated as cathodes for solid-oxide fuel cells (SOFCs) containing a stabilized zirconia electrolyte. The introduction of Sc3+ into the B-site of La0.8Sr0.2MnO3−δ (LSM) led to a decrease in the oxides’ thermal expansion coefficients and electrical conductivities. Among the various LSSMy oxides tested, LSSM0.05 possessed the smallest area-specific cathodic polarization resistance, as a result of the suppressive effect of Sc3+ on surface SrO segregation and the optimization of the concentration of surface oxygen vacancies. At 850 °C, it was only 0.094 Ω cm2 after a current passage of 400 mA cm−2 for 30 min, significantly lower than that of LSM (0.25 Ω cm2). An anode-supported cell with a LSSM0.05 cathode demonstrated a peak power density of 1300 mW cm−2 at 850 °C. The corresponding value for the cell with LSM cathode was 450 mW cm−2 under the same conditions. The LSSM0.05 oxide may potentially be a good cathode material for IT-SOFCs containing doped zirconia electrolytes. 相似文献
8.
Lithium has been chemically extracted from the layered oxide solid solutions Li[Li1/3Mn2/3]O2–(z)Li[Mn0.5−yNi0.5−yCo2y]O2 (0 ≤ y ≤ 1/2 and 0.25 ≤ z ≤ 0.75) and characterized by X-ray diffraction. The weak super lattice reflections that occur in the parent samples at around 2θ = 20–25° vanish on extracting a significant amount of lithium due to the removal of lithium from the transition metal layer and a consequent loss of the ordering between the Li+ and the transition metal ions. Additionally, the chemical delithiation process results in an incorporation of some protons from the chemical delithiation medium into the layered lattice, which has an influence on the structure of the delithiated samples. While the incorporation of a higher concentration (0.4 per formula unit) of protons results in the formation of O1 or P3 phases, delithiated samples with <0.2 protons maintain the initial O3 structure. However, the electrochemically charged samples maintain the initial O3 structure. 相似文献
9.
Ceria co-doped with Sm3+ and Nd3+ powders are successfully synthesized by citric acid–nitrate low-temperature combustion process. In order to optimize the electrical properties of the series of ceria co-doped with Sm3+ and Nd3+, the effects of co-doping, doping content and sintering conditions on grain and grain boundary conductivity are investigated in detail. For the series of Ce0.9(SmxNd1−x)0.1O1.95 (x = 0, 0.5, 1) and Ce1−x(Sm0.5Nd0.5)xOδ (x = 0.05, 0.10, 0.15, 0.20) sintered under the same condition, Ce0.9(Sm0.5Nd0.5)0.1O1.95 exhibits both higher grain and grain boundary conductivity. Compared with Ce0.9Gd0.1O1.95 and Ce0.8Sm0.2O1.9, Ce0.9(Sm0.5Nd0.5)0.1O1.95 sintered at 1350–1400 °C shows higher total conductivity with the value of 1.0 × 10−2 S cm−1 at 550 °C. In addition, it can be found the trends of grain and grain boundary activation energies of Ce1−x(Sm0.5Nd0.5)xOδ are both consistent with those of Ce1−xNdxOδ, but different from those of Ce1−xSmxOδ, which can be explained as: the local ordering of oxygen vacancies maybe occurs more easily in Nd-doped ceria than in Sm-doped ceria; the segregation amount of Sm3+ is more than that of Nd3+ to the grain boundaries in ceria co-doped with Sm3+ and Nd3+, which is confirmed by X-ray photoelectron spectroscopy (XPS). 相似文献
10.
Transition metal mixed oxides of Fe, Cr and Mo with nominal compositional formula, FexCr2−x(MoO4)3 (x = 0, 0.25, 0.50 and 0.75) have been obtained by a co-precipitation method and investigated for their structural and electrocatalytic properties by XRD, TEM, XPS, BET, electrochemical impedance spectroscopy and anodic Tafel polarization. Results show that introduction of Fe for Cr from 0.25 to 0.75 mol into the Cr2(MoO4)3 matrix improved the electrocatalytic activity toward the O2 evolution reaction (OER) in 1 M KOH considerably; the magnitude of improvement being maximum with 0.5 mol Fe. Values of the Tafel slope were close to 35 mV at low and 2.303RT/F at high overpotentials on Fe-substituted oxides. The OER follows nearly second order kinetics in OH− concentration at low overpotentials. 相似文献
11.
The composite cathode system is examined for suitability on a Ce0.9Gd0.1O2−δ electrolyte based solid oxide fuel cell at intermediate temperatures (500–700 °C). The cathode is characterized for electronic conductivity and area specific charge transfer resistance. This cathode system is chosen for its excellent thermal expansion match to the electrolyte, its relatively high conductivity (115 S cm−1 at 700 °C), and its low activation energy for oxygen reduction (99 kJ mol−1). It is found that the decrease of sintering temperature of the composite cathode system produces a significant decrease in charge transfer resistances to as low as 0.25 Ω cm2. The conductivity of the cathode systems is between 40 and 88 S cm−1 for open porosities of 30–40%. 相似文献
12.
Cheng Peng Juri Melnik Jinxia Li Jingli Luo Alan R. Sanger Karl T. Chuang 《Journal of power sources》2009,190(2):447-452
ZnO-doped BaZr0.85Y0.15O3−δ perovskite oxide sintered at 1500 °C has bulk conductivity of the order of 10−2 S cm−1 above 650 °C, which makes it an attractive proton-conducting electrolyte for intermediate-temperature solid oxide fuel cells. The structure, morphology and electrical conductivity of the electrolyte vary with sintering temperature. Optimal electrochemical performance is achieved when the sintering temperature is about 1500 °C. Cathode-supported electrolyte assemblies were prepared using spin coating technique. Thin film electrolytes were shown to be dense using SEM and EDX analyses. 相似文献
13.
Bin Lin Mingjun Hu Jianjun Ma Yinzhu Jiang Shanwen Tao Guangyao Meng 《Journal of power sources》2008,183(2):479-484
A stable, easily sintered perovskite oxide BaCe0.5Zr0.3Y0.16Zn0.04O3−δ (BCZYZn) as an electrolyte for protonic ceramic membrane fuel cells (PCMFCs) with Ba0.5Sr0.5Zn0.2Fe0.8O3−δ (BSZF) perovskite cathode was investigated. The BCZYZn perovskite electrolyte synthesized by a modified Pechini method exhibited higher sinterability and reached 97.4% relative density at 1200 °C for 5 h in air, which is about 200 °C lower than that without Zn dopant. By fabricating thin membrane BCZYZn electrolyte (about 30 μm in thickness) on NiO–BCZYZn anode support, PCMFCs were assembled and tested by selecting stable BSZF perovskite cathode. An open-circuit potential of 1.00 V, a maximum power density of 236 mW cm−2, and a low polarization resistance of the electrodes of 0.17 Ω cm2 were achieved at 700 °C. This investigation indicated that proton conducting electrolyte BCZYZn with BSZF perovskite cathode is a promising material system for the next generation solid oxide fuel cells. 相似文献
14.
Ling Zhao Beibei He Bin Lin Hanping Ding Songlin Wang Yihan Ling Ranran Peng Guangyao Meng Xingqin Liu 《Journal of power sources》2009,194(2):835-837
A dense BaZr0.1Ce0.7Y0.2O3−δ (BZCY) electrolyte is fabricated on a porous anode by in situ drop-coating method which can lead to extremely thin electrolyte membrane (10 μm in thickness). The layered perovskite structure oxide PrBaCo2O5+δ (PBCO) is synthesized by auto ignition process and initially examined as a cathode for proton-conducting IT-SOFCs. The electrical conductivity of PrBaCo2O5+δ (PBCO) reaches the general required value for the electrical conductivity of cathode absolutely. The single cell, consisting of PrBaCo2O5+δ (PBCO)/BaZr0.1Ce0.7Y0.2O3−δ (BZCY)/NiO-BaZr0.1Ce0.7Y0.2O3−δ (BZCY) structure, is assembled and tested from 600 to 700 °C with humidified hydrogen (3% H2O) as the fuel and air as the oxidant. An open-circuit potential of 1.01 V and a maximum power density of 545 mW cm−2 at 700 °C are obtained for the single cell, and a low polarization resistance of the electrodes of 0.15 Ω cm2 is achieved at 700 °C. 相似文献
15.
Junliang Li Shaorong Wang Zhenrong Wang Renzhu Liu Tinglian Wen Zhaoyin Wen 《Journal of power sources》2009,194(2):625-630
La0.84Sr0.16MnO3−δ–Bi1.4Er0.6O3 (LSM–ESB) composite cathodes are fabricated by impregnating LSM electronic conducting matrix with the ion-conducting ESB for intermediate-temperature solid oxide fuel cells (IT-SOFCs). The performance of LSM–ESB cathodes is investigated at temperatures below 750 °C by AC impedance spectroscopy. The ion-impregnation of ESB significantly enhances the electrocatalytic activity of the LSM electrodes for the oxygen reduction reactions, and the ion-impregnated LSM–ESB composite cathodes show excellent performance. At 750 °C, the value of the cathode polarization resistance (Rp) is only 0.11 Ω cm2 for an ion-impregnated LSM–ESB cathode, which also shows high stability during a period of 200 h. For the performance testing of single cells, the maximum power density is 0.74 W cm−2 at 700 °C for a cell with the LSM–ESB cathode. The results demonstrate the ion-impregnated LSM–ESB is one of the promising cathode materials for intermediate-temperature solid oxide fuel cells. 相似文献
16.
Milan Zunic Laure Chevallier Francesca Deganello Alessandra DEpifanio Silvia Licoccia Elisabetta Di Bartolomeo Enrico Traversa 《Journal of power sources》2009,190(2):417-422
Proton conducting BaCe0.9Y0.1O3−x (BCY10) thick films are deposited on cermet anodes made of nickel–yttrium doped barium cerate using electrophoretic deposition (EPD) technique. BCY10 powders are prepared by the citrate–nitrate auto-combustion method and the cermet anodes are prepared by the evaporation and decomposition solution and suspension method. The EPD parameters are optimized and the deposition time is varied between 1 and 5 min to obtain films with different thicknesses. The anode substrates and electrolyte films are co-sintered at 1550 °C for 2 h to obtain a dense electrolyte film keeping a suitable porosity in the anode, with a single heating treatment. The samples are characterized by field emission scanning electron microscopy (FE-SEM) and energy dispersion spectroscopy (EDS). A prototype fuel cell is prepared depositing a composite La0.8Sr0.2Co0.8Fe0.2O3 (LSCF)–BaCe0.9Yb0.1O3−δ (10YbBC) cathode on the co-sintered half cell. Fuel cell tests that are performed at 650 °C on the prototype single cells show a maximum power density of 174 mW cm−2. 相似文献
17.
Malathi Jeyapandian Sandra Lavina Savitha Thayumanasundaram Hiroyuki Ohno Enrico Negro Vito Di Noto 《Journal of power sources》2010,195(1):341-353
This report presents detailed studies on the elemental analysis, vibrational spectroscopy, thermal stability and electrical spectroscopy of two new hybrid inorganic–organic polymers which have been synthesised by a sol–gel method using glycerol and zirconium(IV)butoxide as precursors. These materials have been doped by means of 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMIm-TFSI) ionic liquid (IL), which is insoluble in water. The elemental composition of the obtained polymers [Zr(C6O5H11)] (1) and [Zr(C11O4H31)] (2) has been determined by CHN analysis and by ICP-AES measurements. FT-IR and FT-Raman spectroscopy investigations have been performed to study the molecular structure of the polymers and the interactions of EMIm-TFSI with the host networks. Differential scanning calorimetry measurements show the presence of at least one glass transition temperature (Tg) in both 1 and 2 materials. The broadband dielectric spectroscopic measurements have been carried out between 10−2 Hz to 10 MHz from −100 °C to 100 °C with a 5 °C step. The conductivities of the polymers 1 and 2 have been found to be in the order of 10−8 to 10−11 S cm−1 at 25 °C, so they can be defined as dielectric materials. After doping 2 with EMIm-TFSI, the conductivity at 25 °C of the obtained complex [Zr(C11O4H31)]15/(EMIm-TFSI) (2′) increased three orders of magnitude resulting ca. 10−5 S cm−1. The permittivity spectra revealed two relaxation bands which were attributed to the α relaxation modes of the polymer networks. 相似文献
18.
Synthesis and characterization of oxygen-rich delafossite CuYO2+x—Application to H2-photo production
M. Younsi S. Saadi A. Bouguelia A. Aider M. Trari 《Solar Energy Materials & Solar Cells》2007,91(12):1102-1109
Here we report the synthesis and photo electrochemical properties of super oxides CuYO2.50 and CuYO2.25 prepared from the delafossite CuYO2, respectively, by thermal oxidation at 380 °C under O2-flow and soft chemistry in NaBrO solution (5 N). Their applications as catalysts for H2 evolution upon visible light were investigated. The oxygen insertion was accompanied by partial oxidation of Cu+. For CuYO2.25, the chemical analyses revealed the presence of mixed valent states containing at least formally an equal number of Cu+ and Cu2+. The thermal analysis (TGA) under reducing atmosphere indicates that oxygen is inserted in different crystallographic sites, for CuYO2.25 it exhibits a two-step reduction mechanism with restoration of the parent oxide. In air, CuYO2+x is thermally stable up to 500 °C above which it undergoes irreversible conversion into Cu2Y2O5. They display p-type behavior ascribed to oxygen insertion and the conduction occurs by hopping mechanism between mixed copper valences. Under illumination, the oxides are stabilized by hole consumption reactions involving SO32− and S2− as holes scavengers. The flat-band potentials, lying between 0.17 and 0.26 VSCE, allow a spontaneous H2-photo formation. The rate of H2-evolution is altered by the oxygen insertion and the best photo activity (1.33 μmol h−1 mg−1) was obtained over CuYO2.25 immersed in S2− solution (0.025 M); CuYO2 is also reported for a comparison goal. Over time, the photoactivity is slowed down because of the competitive reduction of H2O with the final products namely S2O62− and Sn2−. 相似文献
19.
An La0.6Sr0.4Co0.2Fe0.8O3–La0.8Sr0.2MnO3 (LSCF–LSM) multi-layer composite cathode for solid oxide fuel cells (SOFCs) was prepared on an yttria-stabilized zirconia (YSZ) electrolyte by the screen-printing technique. Its cathodic polarization curves and electrochemical impedance spectra were measured and the results were compared with those for a conventional LSM/LSM–YSZ cathode. While the LSCF–LSM multi-layer composite cathode exhibited a cathodic overpotential lower than 0.13 V at 750 °C at a current density of 0.4 A cm−2, the overpotential for the conventional LSM–YSZ cathode was about 0.2 V. The electrochemical impedance spectra revealed a better electrochemical performance of the LSCF–LSM multi-layer composite cathode than that of the conventional LSM/LSM–YSZ cathode; e.g., the polarization resistance value of the multi-layer composite cathode was 0.25 Ω cm2 at 800 °C, nearly 40% lower than that of LSM/LSM–YSZ at the same temperature. In addition, an encouraging output power from an YSZ-supported cell using an LSCF–LSM multi-layer composite cathode was obtained. 相似文献
20.
Jae-Wung Lee Ze Liu Lei Yang Harry Abernathy Song-Ho Choi Hyoun-Ee Kim Meilin Liu 《Journal of power sources》2009,190(2):307-310
Thin films of La0.6Sr0.4Co0.2Fe0.8O3−δ (LSCF) were deposited on (1 0 0) silicon and on GDC electrolyte substrates by rf-magnetron sputtering using a single-phase oxide target of LSCF. The conditions for sputtering were systematically studied to get dense and uniform films, including substrate temperature (23–600 °C) background pressure (1.2 × 10−2 to 3.0 × 10−2 mbar), power, and deposition time. Results indicate that to produce a dense, uniform, and crack-free LSCF film, the best substrate temperature is 23 °C and the argon pressure is 2.5 × 10−2 mbar. Further, the electrochemical properties of a dense LSCF film were also determined in a cell consisting of a dense LSCF film (as working electrode), a GDC electrolyte membrane, and a porous LSCF counter electrode. Successful fabrication of high quality (dense and uniform) LSCF films with control of thickness, morphology, and crystallinity is vital to fundamental studies of cathode materials for solid oxide fuel cells. 相似文献