阳极组分对热喷涂制备SOFC输出特性的影响

针对传统管状与板块结构SOFC的特点,提出了集两种结构设计的优点为一体的金属陶瓷支撑管状结构SOFC,并采用低成本的火焰喷涂与等离子喷涂制备电池各结构层.采用3种不同成分与结构的阳极探讨了阳极结构对电池输出特性的影响,结果表明,阳极结构对电池运行时的极化产生显著影响,采用小颗粒的NiO与YSZ的复合粉末制备的阳极,可以有效增加阳极的三相界面,从而降低阳极极化,显著提高电池的输出功率密度,1000℃时可达到最大值0.57 W/cm2.这些结果为优化电池阳极结构层的设计与制备提供了依据.     

流延法制备的SOFC阳极及其性能

研究了以流延法成型中温平板式固体氧化物燃料电池(IT-SOFC)Ni-YSZ阳极基底金属陶瓷,并成功地制备出厚度为200-500μm的该金属陶瓷基底材料.在其中添加不同种类的成孔剂以增加孔隙率.对以该流延工艺制备的素坯及复合陶瓷的性能进行了研究,其中,素坯膜的热烧结性能通过热重-差示扫描分析进行了研究;复合陶瓷基体材料的孔隙率以阿基米德排水法进行了测试;并以扫描电子显微镜观察了其微观形貌.确定了NiO-YSZ基底材料的预烧及成瓷烧结温度范围.随着烧结温度的升高,孔隙率逐渐下降.其中,有机成孔剂和无机成孔剂在造孔性能方面还存在着某些方面的差异.     

NiO-YSZ/YSZ复合梯度材料制备工艺与性能

探索了以NiO和YSZ微粉为原料,采用干压成型的方法制备NiO-YSZ/YSZ复合材料的工艺过程.实验结果表明随着NiO含量的减少,实验样品收缩率和相对密度均逐渐增加;当NiO含量从46%(体积分数,下同)降为30%时,1400℃,1 h下得到的样品收缩率由17.6%逐渐增至21.8%,相对密度由64.04%增至75.93%;1450℃,2 h下得到的样品收缩率则由21.2%逐渐增至23.3%,相对密度也由66.9%增至74.2%.选用1400℃,1 h的烧结工艺能得到晶粒大小均匀,晶粒尺寸较小的复合材料.各复合层的收缩率差值在1%以上,即可造成不同程度的翘曲.要以干压成型制备NiO-YSZ/YSZ复合梯度材料,3层复合是远远不够的.复合梯度材料较好地改善电极与电解质间的界面接触状态,为其在燃料电池上的应用奠定了基础.     

燃烧法制备中温SOFC电解质及其电极材料

采用一种新的燃烧合成陶瓷粉体的方法——硝酸盐-柠檬酸盐燃烧法低温合成中温SOFC所有元件的初始粉体并组装成单电池，电池的电解质材料为Ce0.8Gd0.2O1.9，阴极材料为掺杂一定量固体电解质的La0.6Sr0．4Fe0.8Co0.2O3，阳极材料为固体电解质与NiO的复合材料。单电池的性能测试结果表明：单电池的输出电压和输出电流皆随其运行温度升高而增大，同时单电池的开路电压随温度升高而下降。以Ce0.8Gd0.2O1.9电解质材料为电解质的单电池在750℃的最大输出功率密度约为85mW／cm^2。     

燃烧法制备中温SOFC电解质及其电极材料

采用一种新的燃烧合成陶瓷粉体的方法--硝酸盐-柠檬酸盐燃烧法低温合成中温SOFC所有元件的初始粉体并组装成单电池,电池的电解质材料为Ce0.8Gd0.2O1.9,阴极材料为掺杂一定量固体电解质的La0.6Sr0.4Fe0.8Co0.2O3,阳极材料为固体电解质与NiO的复合材料.单电池的性能测试结果表明:单电池的输出电压和输出电流皆随其运行温度升高而增大,同时单电池的开路电压随温度升高而下降.以Ce0.8Gd0.2O1.9电解质材料为电解质的单电池在750℃的最大输出功率密度约为85 mW/cm2.     

燃烧法制备SOFC用Ni/YSZ阳极材料

以Y(NO3)3、Zr(NO3)4、Ni(NO3)2和有机燃料为原料,采用低温燃烧法制备了NiO/YSZ复合粉料,然后于800℃在H2中还原制备了Ni/YSZ阳极材料.研究了燃烧合成过程中氧化物与有机燃料的配比对反应产物的影响.结果表明当氧化物与燃料的比例为23时,低温燃烧后可成功合成结晶充分的NiO/YSZ粉体.对合成粉体的SEM、TEM观察以及制备的Ni/YSZ阳极材料的SEM观察结果表明,低温燃烧合成的NiO/YSZ粉体细小且两相混合均匀,颗粒粒径为0.5 μm～1 μm.与机械混合法相比,采用燃烧法合成粉体,干压成型制备的Ni/YSZ阳极材料,不仅Ni在YSZ基质中分布更均匀,而且金属陶瓷中的两相均形成了连续的网络结构.     

燃料电池Ni／SCO阳极流延膜的性能研究

以有机基流延工艺制备出了不同Ni含量的NiO／Sm0.2Ce0.8O1.9(NiO／SCO)燃料电池阳极支撑体膜。研究了制备工艺条件和Ni含量等因素对阳极膜微结构和性能的影响。试验结果表明：NiO／SCO流延生坯的烧结温度对最终阳极烧结体的孔隙特性有着决定的影响；为获得具有较高孔隙率和一定孔径分布的阳极烧结体，生坯的烧结温度应不超过1350℃；此外，不同含Ni量阳极流延生坯的烧结行为及烧结体的性能也存在明显的差异，在相同的烧结温度下，高含Ni量阳极烧结体的孔隙率和孔径都明显小于低含Ni量的烧结体，其晶粒的平均尺寸则增大。对不同温度下Ni／SCO阳极电导率的测量结果则表明，Ni／SCO阳极的导电性能也与其Ni含量和制备工艺有着密切的关系。     

连接体合金在SOFC还原气氛下氧化膜的形成及热应力分析

针对新型金属连接体材料Fe-Cr-Co合金,通过750℃的循环氧化实验研究其在SOFC阳极气氛(N2+2％H2+60％H2O)下的高温氧化行为,随后基于真实氧化膜和合金的界面微观形貌进行热应力分析.利用X射线衍射仪(XRD)和配备能谱仪(EDS)的场发射扫描电子显微镜(SEM)对合金氧化膜的相结构和截面形貌以及成分进行...     

BaO-CaO-Al2O3-SiO2系玻璃陶瓷在SOFC中的应用

研究了BaO-CaO-Al2O3-SiO2体系玻璃陶瓷封接材料在固体氧化物燃料电池中的应用.该体系封接材料与铁酸镧(LSF)阴极材料和Fe-Cr合金连接体之间具有良好的热膨胀性能匹配性,良好的粘接性,并且封接材料与两种电池材料之间有良好的稳定性和相容性,BaO-CaO-Al2O3-SiO2体系玻璃陶瓷可以作为固体氧化物燃料电池的封接材料.     

Co掺杂SrTiO_3阳极材料性能研究

通过高温固相合成法制备了SrCoxTi1-xO3,并通过X射线衍射仪、扫描电镜、密度和电导率的测量,系统地研究了掺杂量对Co掺杂的SrTiO3性能的影响,研究了Co掺杂的SrTiO3与电解质材料(YSZ)的兼容性。研究表明,在1500℃还原气氛(5%H2+95%Ar)下,Co在SrTiO3中的掺杂量在10mol%以下。SrCoxTi1-xO3的电导率呈现离子电导的特征,并随着Co掺杂量的增加而减小。SrCo0.05Ti0.95O3与YSZ在1100℃以下可以稳定共存。     

Ni-YSZ films deposited by reactive magnetron sputtering for SOFC applications

Ni-YSZ films are deposited by reactive magnetron sputtering from a single Ni/Zr/Y metallic target at rates as high as 4 µm h^− 1. Tailoring both DC pulsed power and oxygen partial pressure, a stable deposition process was obtained. Columnar morphology was observed in the as-deposited films. Annealing in air at 900 °C was conducted, after which a fully crystallized structure was achieved. Chemical composition has been measured by Rutherford Backscattering Spectroscopy (RBS) and Nuclear Reaction Analysis (NRA). To find optimal conditions for reactive deposition of the films, effect of oxygen flow rate on the discharge parameters was studied. Film deposition onto glass substrates was carried out to measure electrical conductivity.     

A novel approach to co-sintering of doped lanthanum chromite interconnect on Ni-YSZ anode substrate for SOFC applications

A cost-effective method was developed to fabricate dense doped LaCrO₃ bases interconnect membrane on anode substrate for solid oxide fuel cell (SOFC) applications. As conventional lanthanum chromite interconnect is difficult to be co-sintered with green anode, a simple and cost effective screen printing/co-sintering process was employed, and dense La_1−x−ySr_xCa_yCrO_3−δ interconnect membrane was successfully prepared on the anode support of NiO-YSZ. In this method a base layer of doped lanthanum chromite (La_1−xSr_xCrO_3−δ) was applied on NiO-YSZ substrate and a top layer of CaCrO₄ was then coated and co-sintered to melt the top layer. By means of this method, not only CaCrO₄ melts and fills the open pores in the base layer, but it also dissolves in base layer forming La_1−x−ySr_xCa_yCrO_3−δ as a single layer. The sintering characteristics, microstructure and electrical conductivity of interconnect were investigated. In addition, the effects of composition on sintering and electrical properties were studied.     

Formation of nanostructured YSZ/Ni anode with pore channels by plasma spraying

YSZ/Ni is the conventionally most used material for making the anode of a solid oxide fuel cell. Agglomerated nanostructured YSZ/NiO powders and plasma spray are applied to produce nanostructured YSZ/NiO coatings on porous support substrates. After reduction in an ambient atmosphere of 7% hydrogen and 93% argon at about 800 °C for 4 hours, a novel SOFC anode with nanostructured characteristics such as nano YSZ particles, nano Ni particles, nano pores and nano pore channels is produced. This new YSZ/Ni anode provides larger triple phase boundaries for hydrogen oxidation reactions. X-ray diffraction patterns of these YSZ/NiO coatings after 1 h of heat treatment at temperatures from 700 to 1100 °C are obtained and Scherrer analysis is conducted to study the effect of temperature on grain size. The results obtained from SEM, TEM, XRD and EDX measurements and analyses are presented in this investigation.     

Electrocatalysis of carbon anode in aluminium electrolysis

The anodic overvoltage of the carbon anode in aluminum electrolysis is of the order of 0.6 V at normal currem densities. However, it can be reduced somewhat by doping the anode carbon with various inorganic compounds. A new apparatus was designed to improve the precision of overvoltage measurements. Anodes were doped with MgAl2O4 and AlF3both by impregnation of the coke and by adding powder, and the measured overvoltage was compared with that of undoped samples. For prebake type anodes baked at around 1150℃, the anodic overvoltage was reduced by 40-60 mV,and for Soderberg type anodes, baked at 950 ℃, by 60-80 mV.     

Microstructure characterization and electrical conductivity of electroless nano Ni coated 8YSZ cermets

Using a common electroless bath, Ni-8YSZ (Ni-8 mol% yttria stabilized zirconia) composite nano powder have been synthesized without use of any expensive sensitizing agent. HRTEM micrographs indicated that the coating morphology of Ni nano particles on the 8YSZ showed a spotty, discontinuous distribution and the Ni nano particles appeared as a crystalline phase. The amount of Ni in the composite powders was varied from 36-51 wt.% by changing the substrate powder loading in the electroless bath. Bar type samples were prepared by uniaxial pressing and sintering at 1300 °C for 2 h with these coated powders. The cubic (c)-zirconia was found to partially dissociate into monoclinic (m)-zirconia on sintering with Ni content 41% or higher and also increases with the increase of Ni content. The microstructure of each Ni-YSZ cermet after reduction in a H₂ + Ar gas atmosphere showed dual scale porosity (micro and submicron porosity). The Ni-8YSZ cermet samples showed metallic electrical conduction behavior, proving the percolation capability of the synthesized nano composite.     

Cr doping effect in B-site of La<Subscript>0.75</Subscript>Sr<Subscript>0.25</Subscript>MnO<Subscript>3</Subscript> on its phase stability and performance as an SOFC anode

La_0.75Sr_0.25Cr _y Mn_1−y O₃ (LSCM) (y = 0.0–0.6) composite oxides were synthesized by a complexing process of combining ethylene diamine tetraacetic acid (EDTA) and citrate. X-ray diffraction (XRD), temperature-programmed reduction, electrical conductivity, I–V polarization, and impedance spectroscopy were conducted to investigate the Cr doping effect of La_0.75Sr_0.25MnO₃ on its phase stability and electrochemical performance as a solid-oxide fuel cell (SOFC) anode. The chemical and structural stabilities of the oxides increased steadily with increasing Cr doping concentration, while the electrical conductivity decreased on the contrary. At y ≥ 0.4, the basic perovskite structure under the anode operating condition was sustained. a cell with 0.5-mm-thick scandia-stabilized zirconia electrolyte and La_0.75Sr_0.25Cr _y Mn_1−y O₃ anode delivered a power density of ∼15 mW·cm⁻² at 850°C.