阳极支撑三层一体化结构电池的制备及性能

采用流延工艺制备了NiO-8％Y2O3/ZrO2(YSZ)阳极支撑三层一体化结构单电池,在此基础上采用浸渍工艺在多孔YSZ基体上低温制备了高活性阴极La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF).研究发现:降低电极制备温度可以得到微观形貌可控、分布均匀的纳米电极,并且避免了电极与基体间的反应:通过控制浸渍次数,制备了不同LSCF含量的电池;随着浸渍量的增加,电极的极化电阻显著下降;在800℃时,LSCF质量分数为45％的电池的功率密度高达1090 mW/cm2,同时电池稳定运行90h,表现出了很好的稳定性.     

流延法制备Ni-YSZ/YSZ复合基膜及性能测试

采用传统有机流延法制备NiO-YSZ/YSZ复合基膜,其中包括流延浆料配制及流延工艺过程.采用共烧结方式制备均匀平整的SOFC多孔阳极支撑的致密电解质膜,阳极支撑层厚度1000 μm、阳极功能层20 μm、致密电解质层40 μm左右.并对阳极孔隙率和电解质气体渗透率、显微结构及膨胀系数等进行测试.结果表明通过复合流延的方式可以制备出具有良好组织结构和性能的SOFC阳极支撑系统.     

高孔隙率YSZ-高致密YSZ薄膜共烧复合体的制备

在中温固体氧化物燃料单电池制备过程中,用聚乙烯吡咯烷酮包裹改性的石墨粉体为造孔剂,以8%(摩尔分数)Y2O3稳定的ZrO2(8%in mole yttria stabilized zirconia,YSZ)粉体+石墨造孔剂为支撑层原料,与自制的水系流延YSZ电解质薄膜一起共压,制备了YSZ+石墨–YSZ薄膜复合体,在1 470℃下共烧4 h后获得高孔隙率YSZ–高致密YSZ薄膜共烧复合体。研究了不同溶剂体系中石墨含量和粒度对共烧体的影响。结果表明:选用粒径为6μm以下的石墨粉体作造孔剂能获得无开裂的多孔YSZ–YSZ薄膜共烧体,其共烧体为双层结构,层间结合紧密、结构均匀,孔隙率高达68%(体积分数)。在造孔剂的含量变化与材料烧成收缩率的关系中,造孔剂含量存在1个最佳含量值,当造孔剂含量在最佳值附近时,制备的共烧复合体质量最好。该最佳含量值随造孔剂颗粒尺寸大小不同而变化。     

不同黏结剂体系对水基流延成型Y2O3稳定ZrO2的影响

分别采用聚乙烯醇(potyvinyl alcohol,PVA)、乳胶B1070和PVA B1070复合黏结剂体系,水系流延成型法制备固体氧化物燃料电池(solid oxidefuel cell,SOFC)电解质8%(摩尔分数)Y2O3稳定的ZrO2(8YSZ)薄膜.研究了不同黏结剂对流延工艺以及对流延坯片的影响.结果表明:不同黏结剂加入后浆料的黏度和剪切变稀程度随PVA加入量的增加而增大.相反,浆料的黏度和剪切变稀程度随B1070加入量的增大而减小.发现使用不同黏结剂对流延坯片的生坯密度和干燥收缩具有重要的影响.8YSZ坯片的烧结密度随着生坯密度增大而增大,以300(质量分数,下同)PVA 70?070为复合黏结剂,8YSZ与黏合剂的质量比为0.93,流延成型的坯体在1 400℃保温2 h烧结能获得相对密度达98.5%的SOFC电解质8YSZ薄膜.     

实心多孔支撑体全膜化微型固体氧化物燃料电池的制备及性能

提出一种实心多孔支撑体全膜化微型固体氧化物燃料电池(micro solid oxide fuel cell,μSOFC)设计模型.电池用氧化钇部分稳定的氧化锆[(ZrO2)0.97(Y2O3)0.03,partially stabilized zirconia,PSZ]多孔陶瓷作为支撑体,在其上制备NiO-YSZ阳极层,分别采用离心和浸渍两种成膜工艺制备YSZ电解质膜,以La0.8Sr0.2MnO3-YSZ复合材料为阴极,对组装好的单电池进行了电化学性能测试.在850℃和800℃时,离心沉积工艺制备的单电池最大输出功率密度分别为286 mW/cm2和254 mW/cm2,而浸渍涂布法制备单电池的最大输出功率密度则分别达到572 mW/cm2和388 mW/cm2.电化学阻抗谱显示;电极极化是影响电池性能的主要因素.     

中温固体氧化物燃料电池电解质材料及其制备工艺的研究发展趋势

综合介绍了中温固体氧化物燃料电池(solid oxide fuel cells,SOFCs)的电解质材料以及薄膜的制备工艺.中温SOFCs的工作温度应低于800℃,甚至低于750℃,为600～800℃.固体氧化物电解质的晶体结构基本上属于下列两类:面心立方的萤石型和立方型钙钛矿晶体结构.稳定ZrO2是萤石型结构电解质的一个典型代表.8%(摩尔分数,下同)氧化钇稳定氧化锆(8%in mole Y2O3 stabilized ZrO2,8YSZ),其在1 000℃左右才有可观的离子电导率(0.1 S/cm).在800℃,氧化钪掺杂氧化锆(Zr0.9Sc0.1O1.95,scandia doped zirconia,SSZ)的电导率(0.1 S/cm)比Zr0.9Sc0.1O1.95(10YSZ)的(0.03S/cm)高得多.Sm掺杂的CeO2(samarium doped ceria,CSO)电解质有希望应用于中温SOFCs.Sr和Mg掺杂LaGaO3(LSGM)氧离子导体已成为中低温SOFCs重要候选电解质材料.改进氧化锆基电解质的电导性能的另一个途径是薄膜化.厚度小于10 μm的YSZ基SOFCs,在800℃,0.8V时的功率密度可达800mW/cm2.薄膜比厚膜能提供更好的化学均匀性和更易控制成分.SOFCs要求精细和尺度小时,通常选择薄膜;而低成本和大尺寸时,通常选择厚膜.成本较低的膜成型工艺有等离子喷涂、胶态成型工艺、流延成型、冷冻干燥成型、丝嘲印刷和真空泥浆浇注等.     

固体氧化物燃料电池YSZ电解质薄膜的制备方法概述

固体氧化物燃料电池(SOFC)是一类既能发电,又无噪声污染、高效清洁的能量转换装置. 氧化钇稳定的氧化锆(YSZ)是应用最为广泛的SOFC电解质材料. SOFC制备的关键技术之一是获得足够薄且不透气的YSZ电解质薄膜. 本文综述了几种不同的制备YSZ电解质薄膜的方法,并对它们进行了分析和比较,讨论了它们各自的优缺点和应用场合. 最后,对用于固体氧化物燃料电池的YSZ薄膜制备方法进行了评述和展望.     

阳极支撑结构IT-SOFC的阳极及电解质层的水系流延与共烧

采用水系流延成型,共烧制备了平板式中温固体氧化物燃料电池（SolidoxidefuelcellSOFC）的NiO/YSZ阳极支撑电解质氧化钇稳定氧化锆（YSZ）薄膜复合体。通过调节优化浆料的pH值、分散剂和粘度获得了具有均匀的微观结构电解质YSZ与阳极NiO/YSZ流延素坯。调节阳极中的YSZ粉体的颗粒级配,以促使阳极坯片的烧成收缩与电解质坯片的烧成收缩相匹配,获得大面积、平整的阳极与电解质复合烧结体,其中阳极层厚度为0.5～1.0mm,孔隙分布均匀,孔隙率达30vol%以上;电解质厚度为15μm以下,相对密度大于98%;阳极与电解质层界面两者能很好地烧结在一起。     

掺硼金刚石膜微电极的电化学性能

掺硼金刚石膜(BDD)具有良好的力学性质、生物相容性和表面抗污染性,有望在体内植入中保持长期的稳定性。以液态硼酸三甲酯为硼源,采用光刻工艺和选择性生长法制备线宽为200μm和100μm的BDD膜叉指微电极,所制备的微电极边界清晰规整、薄膜质量良好,图形区薄膜的选择性高。采用电化学工作站表征电极在电解质溶液中的循环伏安行为和阻抗特性,结果表明:掺硼金刚石膜电极的尺寸和形状对电化学窗口和背景电流影响较小。200μm和100μm的叉指电极相邻微带电极间扩散方式分别是线性扩散和半球形稳态扩散,100μm叉指电极的CV曲线趋近于半球形稳态扩散的S形。掺硼金刚石膜微电极只有一个时间常数,将利于物质的快速和准确检出。     

丝网印刷法制备固体氧化物燃料电池Ag-GDC电极的研究

银和掺钆的氧化铈(GDC,Ce0.8Gd0.2O1.9)复合而成的Ag-GDC金属陶瓷,可作为固体氧化物燃料电池(Solid Oxide Fuel Cell,SOFC)的对称电极材料,但其制备工艺的研究还很缺乏.研究了丝网印刷工艺在钇稳定化氧化锆(ZrO2)0.92(Y2O3)0.08(YSZ)电解质上制备Ag-GDC...     

Single‐step fabrication of an anode supported planar single‐chamber solid oxide fuel cell

We present single‐step‐co‐sintering manufacture of a planar single‐chamber solid oxide fuel cell (SC‐SOFC) with porous multilayer structures consisting of NiO/CGO, CGO and CGO‐LSCF as anode, electrolyte, and cathode, respectively. Their green tapes were casted with 20 μm thickness and stacked into layers of anode, electrolyte, and cathode (10:2:2), then hot‐pressed at 2 MPa and 60°C for 5 minutes (deemed optimal). Subsequently, hot laminated layers were cut into 40 × 40 mm cells and co‐sintered up to 1200°C via different sintering profiles. Shrinkage behavior and curvature developments of cells were characterized, determining the best sintering profile. Hence, anode‐supported SC‐SOFCs were fabricated via a single‐step co‐sintering process, albeit with curvature formation at edges. Subsequently, anode thickness was increased to 800 μm and electrolyte reduced to 20 μm to obtain SOFCs with drastically reduced curvature with the help of a porous alumina cover plate.     

Synthesis and properties of ultralow dielectric constant porous polyimide films containing trifluoromethyl groups

In this research, a series of porous copolyimide (co‐PI) films containing trifluoromethyl group (CF₃) were facilely prepared via a phase separation process. The co‐PI were synthesized by the reaction of benzophenone‐3,3′,4,4′‐tetracarboxylic dianhydride (BTDA) with two diamines of 4,4′‐diaminodiphenyl ether (ODA) and 3‐trifluoromethyl‐4,4'‐diaminodiphenyl ether (FODA) with various molar ratios. The flexible and tough porous co‐PI films with about 300 μm thickness and 8～10 μm average diameter could be obtained by solution casting conveniently. The thermal properties of the obtained porous co‐PI films were excellent with a glass transition temperature at 270 °C ～ 280 °C and only 5% weight loss in temperature from 530 °C to 560 °C under nitrogen atmosphere. In addition, the dielectric and hydrophobic properties of porous co‐PI films were remarkably improved owing to the presence of trifluoromethyl groups (CF₃) in the polymer chains. Moreover, our synthesized porous co‐PI films also showed good mechanical properties. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44494.     

Thin Yttrium-Stabilized Zirconia Electrolyte Solid Oxide Fuel Cells by Centrifugal Casting

A centrifugal casting technique was developed for depositing thin 8-mol%-yttrium-stabilized zirconia (YSZ) electrolyte layers on porous NiO-YSZ anode substrates. After the bilayers were cosintered at 1400°C, dense pinhole-free YSZ coatings with thicknesses of ∼25 μm were obtained, while the Ni-YSZ retained porosity. After La_0.6Sr_0.4Co_0.2Fe_0.8O₃ (LSCF)-Ce_0.9Gd_0.1O_1.95 (GDC) or La_0.8Sr_0.2MnO₃ (LSM)-YSZ cathodes were deposited, single SOFCs produced near-theoretical open-circuit voltages and power densities of ∼1 W/cm² at 800°C. Impedance spectra measured during cell tests showed that polarization resistances accounted for ∼70%–80% of the total cell resistance.     

Effect of sol infiltrations on electrical properties of PZT

Abstract

Thin PZT films with a thickness of approximately 1 μm can readily be fabricated using a layered sol-gel deposition technique. The maximum thickness obtainable is limited by the time taken and the tendency of the films to crack and spall when many layers are deposited. Thicker layers may be obtained by depositing a powder-sol slurry whereby a PZT powder is mixed with a sol of approximately the same composition. Using this layered slurry deposition technique it is possible to obtain films with a thickness in excess of 20 μm. The resulting films, however, are often porous, leading to poor properties and making subsequent patterning difficult. A technique for increasing the density of such films through the use of controlled heat treatments and sol infiltration is presented. It is shown that with increased levels of sol infiltration the density and dielectric constant of the films are maximised. Measurements of piezoelectric properties indicate that sol infiltrations have no significant effect on d₃₃. A sample with approximately 10% closed porosity was obtained following four infiltration steps per layer. This resulted in a maximum dielectric constant of approximately 700 and a d₃₃ of 70 pC N ^-1 (poling conditions: 8 V μm ^-1 for 5 min at 200°C). Examination of cross-sections of the films produced shows that for intermediate levels of sol infiltration (typically between 1 and 3) a density gradient is obtained with higher densities observed nearer the base of the film. It is postulated that the observed density gradient is a result of continued infiltration from the upper layers when further layers of slurry are deposited. The effects of changing process variables such as the number of infiltration steps and firing temperature on film structure and properties are discussed.     

Enhanced electrochemical properties of Bi-layer La0.5Sr0.5CoO3−δ cathode prepared by a hybrid method

Bi-layer La_0.5Sr_0.5CoO_3−δ (LSCO) cathodes are processed by a hybrid method that combines a seed layer prepared by a pulsed laser deposition (PLD) technique and a conventional cathode layer (∼7 μm in thickness) by a screen printing method. By inserting the PLD seed layer with the thickness of ∼500 nm or less, robust cathode films with desired microstructure and excellent adhesion properties with the underlying electrolyte layer, are successfully fabricated. The area specific resistance (ASR) of the hybrid cathode layers decreases about 5 times compared with that of the single layer cathode films prepared by the conventional screen printing method. The hybrid approach provides a cost-effective way to fabricate thick cathode films with significantly enhanced electrochemical properties for solid oxide fuel cells (SOFCs).     

Electrophoretically deposited thin film electrolyte for solid oxide fuel cell

Abstract

Thin films of 8 mol% yttria stabilised zirconia (YSZ) electrolyte have been deposited on non-conducting porous NiO–YSZ anode substrates using electrophoretic deposition (EPD) technique. Deposition of such oxide particulates on non-conducting substrates is made possible by placing a conducting steel plate on the reverse side of the presintered porous substrates. Thickness of the substrates, onto which the deposition has been carried out, varied in the range 0·5–2·0 mm. Dense and uniform YSZ thin films (thickness: 5–20 μm) are obtained after being cofired at 1400°C for 6 h. The thickness of the deposited films is seemed to be increased with increasing porous substrate thickness. Solid oxide fuel cell (SOFC) performance is measured at 800°C using coupon cells with various anode thicknesses. While a peak power density of 1·41 W cm^?2 for the cells with minimum anode thickness of 0·5 mm is achieved, the cell performance decreases with anode thickness.     

A Simple and Cost-Effective Approach to Fabrication of Dense Ceramic Membranes on Porous Substrates

A simple and elegant approach to fabrication of dense ceramic membranes on porous substrates, a traditional dry pressing of foam powders, has been developed to reduce the cost of fabrication. Gd-doped ceria (GDC, Gd_0.1Ce_0.9O_1.95) electrolyte membranes as thin as 8 μm are obtained by dry-pressing highly porous GDC powders. The membrane thickness can be readily controlled by the amount of powder. The electrolyte membranes are studied in a solid-oxide fuel cell (SOFC) with air as oxidant and humidified hydrogen (3% H₂O) as fuel. Open-circuit voltages of about 1.0 V are observed, implying that the permeability of the membranes to molecular gases is insignificant. Power densities of 140 and 380 mW/cm² are demonstrated at 500° and 600°C, respectively, representing a significant progress in developing low-temperature SOFCs.     

Optimization of the microstructure of porous composite cathodes in solid oxide fuel cells

A comprehensive micromodel to predict the electrochemical performance of porous composite LSM‐YSZ cathodes in solid oxide fuel cells (SOFCs) is developed. The random packing sphere model is used to estimate the cathode microstructural properties required for the micromodel. The micromodel developed takes into account the complex interdependency among the mass transport, electron and ion transports, and the electrochemical reaction, and can be used for optimization of the microstructure of porous LSM‐YSZ composite cathodes. It is shown that the electrochemical performance of these cathodes depends on the microstructural variables of the cathode porosity, thickness, particle size ratio, and size and volume fraction of LSM particles. The effect of these microstructural variables on the cathode total resistance, as the objective function to achieve the optimum microstructure for the cathode, is studied through computer simulation. The results indicated that for a LSM‐YSZ cathode operated at the average temperature of 1073.15 K, bulk oxygen partial pressure of 0.21 atm, and total current density of 5000 Am^?2, and constrained to the minimum value of 1 μm for the size of LSM particles and 0.25 for the cathode porosity, the optimum microstructure is obtained at the particle size ratio of unity, LSM particle size of 1 μm and volume fraction of 0.413, porosity of 0.25, and thickness of 60 μm. The cathode total resistance corresponding to the cathode optimized is estimated to be 0.291 Ω cm². © 2011 American Institute of Chemical Engineers AIChE J, 2012     

清液体系中高性能T型沸石分子筛膜的合成

由摩尔组成为SiO2:Al2O3:Na2O:K2O:H2O=1:0.015:0.25:0.08:25的澄清溶液,在预涂晶种的管状莫来石支撑体上水热合成T型沸石分子筛膜.在高于100℃清液体系中合成出了高性能T型沸石分子筛膜.用X射线衍射(X-ray diffraction,XRD)仪和扫描电子显微镜(scanning electron microscope,SEM)对150℃下合成35 h的分子筛膜进行了表征.XRD谱表明:T型沸石分子筛成功地生长在预涂晶种的支撑体上.支撑体的外表面覆盖着20 μm厚有取向的晶体层.从SEM照片判断,起到分离作用的是生长致密的中间层,而不是表层.在150℃下制备的膜,对水/乙醇、水/异丙醇混合物具有高渗透汽化分离性能.优异的渗透汽化性能归因于在涂有晶种的多孔支撑体上生长了一层高结晶度且缺陷较少的T型沸石分子筛晶体层.