固体氧化物燃料电池连接体材料研究进展

固体氧化物燃料电池(SOFC)是高效、洁净、全固态的电化学装置,是发展比较快的能源技术之一.本文总结了SOFC关键组件连接体材料的研究进展,详细论述了近年发展起来的金属连接体材料的研究状况,总结了目前研究比较广泛的Ni基、Fe基、Cr基连接体合金的性能特点和存在的主要问题,最后介绍了经过表面处理的Fe-Cr基合金应作为SOFC金属连接体材料的研究重点.     

固体氧化物燃料电池材料的发展前景

简要评述了固体氧化物燃料电池（SOFC）材料体系,以及研究开发这一材料体系需要注意的一些关键技术问题。我国丰富的稀土资源可用于开发固体氧化物燃料电池材料,同时具有较好的工业基础和研究实力,这类材料在我国将具有广阔的市场。     

固体氧化物燃料电池合金连接体涂层材料研究进展

固体氧化物燃料电池(SOFC)向中温化发展,使得用金属材料作连接体成为可能.但是金属连接体在SOFC工作的高温氧化和湿氢环境中,其使用寿命受到严重限制,需要表面保护层.常用钙钛矿结构和尖晶石结构类的氧化物作为金属涂层材料.在合金表面涂覆致密氧化物涂层很关键,通过涂层材料与合金挥发出的Cr类元素之间的化学反应,可以降低Cr挥发,减弱Cr对阴极的毒化,阻止合金的进一步氧化.涂层材料还需要有高的电子电导率,与合金匹配的热膨胀性能,以降低界面电阻,防止涂层脱落.目前,还没有哪一种材料能够满足这多方面的要求,因此合金保护涂层材料还需要进一步的研究.     

固体氧化物燃料电池的研究进展

回顾了固体氧化物燃料电池的发展历史以及目前发展状况。介绍了固体氧化物燃料电池的工作原理以及作为燃料电池的阳极、阴极、电解质和连接材料的选择依据。评述了分别应用于阳极、阴极、电解质以及连接材料的材料目前的研究状况和面临的一些问题。最后提出了固体氧化物燃料电池能够得以应用必须解决的一些瓶颈因素。     

涂层在固体氧化物燃料电池金属连接体中的应用

固体氧化物燃料电池工作温度的降低,使铁素体不锈钢用作连接体成为了可能。这类连接体具有热导率高、导电性能好、热膨胀性匹配等优点,但也存在一些问题,如高价Cr的挥发以及抗氧化性弱等。涂层可以改善铁素体不锈钢的相关性能。本文综述了稀土氧化物涂层、钙钛矿涂层以及尖晶石涂层的涂层类型和涂覆方法,比较了在金属连接体中的应用效果。     

固体氧化物燃料电池金属连接体腐蚀研究进展

固体氧化物燃料电池(SOFC)常用廉价、易加工、导电性强的铁素体不锈钢作为连接体材料。然而,SOFC电堆中苛刻环境限制连接体的使用。本文介绍了近年来连接体材料腐蚀行为的研究现状,综述了空气、燃料气氛、双重气氛、微量合金元素、接触环境等因素对连接体腐蚀的影响规律,系统地阐述了连接体材料的腐蚀机理,并指出连接体腐蚀行为研究中存在的不足以及未来发展方向。     

固体氧化物燃料电池铬酸镧连接材料研究现状

掺杂二价减土金属的铬酸镧是目前研究最深入，应用效果最好的固体氧化物燃料电池（SOFC）的连接材料，它几乎占整个SOFC制造成本的一半，本文就其研究现状进行了综述。     

固体氧化物燃料电池封接材料和封接实验研究

平板式固体氧化物燃料电池组元材料的封接一直是困扰SOFC快速发展的瓶颈.实验选定封接材料的组成,通过球磨7h～8h后,1300℃～1600℃高温熔融,快速水淬冷却,获得玻璃状材料,球磨后过175 μ m的筛得到实验用封接材料粉末.热膨胀性能测试结果表明,封接材料的热膨胀系数与电解质和金属连接体在同一数量级,表现出良好的热匹配性.将7种封接材料用于电解质与连接体的连接,从900℃到1300℃分别进行了封接实验,确定了S1,S3,S5,S6和S7最适宜的封接温度.对封接样品进行热循环试验,用吸红实验检验气密性,结果显示,使用封接材料S5和S7的封接样品,封接效果较为理想.扫描电镜观察封接界面的微观形貌表明,封接材料与电解质连接较好,但与金属连接不够紧密.实验结果显示,S1,S3,S5,S6和S7均可用于金属与陶瓷的封接,其中,S5,S6和S7的性能更为稳定.     

等离子喷涂技术在固体氧化物燃料电池中的应用

介绍了等离子喷涂制备固体氧化物燃料电池（SOFC）中的电解质、阴阳极及其功能组件的研究进展,分析了其中的关键技术.研究表明：采用等离子喷涂,通过选择适当的粉末原料,工艺优化和改进送粉方式,可以得到满足SOFC要求的致密电解质,多孔阴极和阳极.三者的厚度均为30～50 μm,SOFC总厚度低于100～120μm,可以将固体氧化物燃料电池的运行温度降低到中温800℃下的范围,降低电池运行温度,从而降低了对相关材料的要求和运行成本.     

固体氧化物燃料电池铈基电解质的研究进展

开发在中、低温下具有高电导率的电解质材料是未来发展低成本固体氧化物燃料电池（SOFC）的重要方向。掺杂氧化铈（DCO）在500~700 ℃时,具有良好的导电性能,其离子电导率远远高于同温度下氧化钇稳定的氧化锆（YSZ）电解质材料,因此其成为中温SOFC电解质材料应用与研究的重点。但DCO在还原气氛下Ce4+部分还原为Ce3+,会引起电子电导增加、制造成本提高、开路电压降低等问题。针对这些问题,大量研究通过稀土或碱金属掺杂、电解质复合进行了探索,发现掺杂和多相电解质复合有助于提高DCO的离子电导率和稳定性。在概述锆基固体电解质、Bi2O3基电解质、LaGaO3基氧化物、CeO2基氧化物等SOFC电解质的基础上,重点综述了单掺杂、双掺杂和多掺杂的氧化铈电解质,同时综述了掺杂氧化铈-碳酸盐复合电解质和两种电解质复合的电解质材料的研究进展。另外,介绍了流延、丝网印刷、浆料涂覆、电泳沉积、喷雾热解、溅射、大气等离子喷涂、激光脉冲沉积等制膜方法,在铈基电解质膜制备方面的应用。最后,对铈基电解质的发展前景和方向进行了展望。     

Evaluation of commercial alloys as cathode current collector for metal-supported tubular solid oxide fuel cells

Ferritic stainless steels have become promising candidate materials for interconnects in tubular metal-supported solid oxide fuel cell stacks. A number of ferritic alloys containing between 18 and 26 mass% Cr and discrete changes in minor alloying elements and reactive elements were isothermally oxidized at 800 °C in air and their electrical resistance was measured with the objective of obtaining an overview of the properties relevant for applications for cathode side interconnect. The alloys containing Mn showed a (Mn,Cr)₃O₄ spinel layer on top of a Cr₂O₃ oxide. The electrical conductivity of the steels forming this kind of oxide layer was higher than the measured for only Cr₂O₃ former or oxide dispersion strengthened alloys and increased when the alloy contained Ti or Nb. Oxide scale spallation was observed for F18TNb and E-Brite, both containing Si. The influence of different cyclic oxidations was studied for the Crofer22APU steel, showing an irregular oxide growth as well as an increase in conductivity of the oxide scale formed when 12-h cycles were applied.     

Ceramic materials containing rare earth oxides for solid oxide fuel cell

Materials for a solid oxide fuel cell were investigated aiming especially at low temperature operation of the cell. Although yttria-stabilized zirconia has been most popularly investigated as an electrolyte for the cell, the conductivity reaches the allowable level only around or higher than 1000 °C. The use of a ceria-based electrolyte, especially samaria doped ceria, significantly lowered the operation temperature of the cell due to its high oxide ion conductivity. The reduction of ceria with H₂ and resultant electronic conduction could be avoided by the coating of YSZ on to the anode side of the ceria. The ceria layer facing the air electrode is effective in reducing cathodic polarization. Ni-ceria cermet exhibited higher fuel electrode performance than Ni-YSZ cermet in lowering polarization.     

Dip coating technique in fabrication of cone-shaped anode-supported solid oxide fuel cells

A simple and cost-effective dip coating technique was successfully developed to fabricate NiO-YSZ anode substrates for cone-shaped anode-supported solid oxide fuel cells. A single cell, NiO-YSZ/YSZ/LSM-YSZ, was assembled and tested to demonstrate the feasibility of the technique applied. Using humidified hydrogen (75 ml/min) as fuel and ambient air as oxidant, the maximum power density of the cell was 0.78 and 1.0 W/cm² at 800 and 850 °C, respectively. The observed open-circuit voltages (OCV) was closed to the theoretical value and the scanning electron microscope (SEM) results revealed that the microstructures of the anode substrate and the cathode layer are porous and the electrolyte film is dense.     

SmBaCoCuO5+x as cathode material based on GDC electrolyte for intermediate-temperature solid oxide fuel cells

The performance of SmBaCoCuO_5+x (SBCCO) cathode has been investigated for their potential utilization in intermediate-temperature solid oxide fuel cells (IT-SOFCs). The powder X-ray diffraction (XRD), thermal expansion and electrochemical performance on Ce_0.9Gd_0.1O_1.95 (GDC) electrolyte are evaluated. XRD results show that there is no chemical reaction between SBCCO cathode and GDC electrolyte when the temperature is below 950 °C. The thermal expansion coefficient (TEC) value of SBCCO is 15.53 × 10⁻⁶ K⁻¹, which is ∼23% lower than the TEC of the SmBaCo₂O_5+x (SBCO) sample. The electrochemical impedance spectra reveals that SBCCO symmetrical half-cells by sintering at 950 °C has the best electrochemical performance and the area specific resistance (ASR) of SBCCO cathode is as low as 0.086 Ω cm² at 800 °C. An electrolyte-supported fuel cell generates good performance with the maximum power density of 517 mW cm⁻² at 800 °C in H₂. Preliminary results indicate that SBCCO is promising as a cathode for IT-SOFCs.     

Compatibility between glass sealants and electrode materials of solid oxide fuel cells

BaO-CaO-Al2O3-SiO2-La2O3-B2O3 system glass materials were investigated as sealants for a solid oxide fuel cell (SOFC).The transition temperature (Tg) and the crystal temperature (Td) values decrease greatly with the increase of BaCO3 content when the other components do not change.For the thermal expansion coefficient (TEC) values,the trend is inverse.The sealant has superior thermal expansion coefficient matching properties with La(Sr)MnO3 (LSM) cathode,La(Sr)FeO3 (LSF) cathode,Ni-LDC (La doped CeO2) anode,and Ni-YSZ (yttria stabilized zirconia) cermet anode.The sealant also has superior stability,compatibility,and good bonding characteristic with these electrode materials at 800-900℃.The results indicate that the aluminosilicate system glass sealant possesses superior compatibility with electrode materials of the solid oxide fuel cell.     

Critical issues in catalytic diesel reforming for solid oxide fuel cells

Developing low-cost diesel-reforming catalysts and improving fuel mixing prior to catalytic reforming were addressed as two critical issues under the current study. Ruthenium-doped lanthanum chromite and aluminite were explored as catalysts for the autothermal reforming of diesel fuel. Dodecane was used as a surrogate fuel. Both catalysts yielded nearly 20 moles of hydrogen per mole of dodecane at oxygen-to-carbon ratios of 0.5 and steam-to-carbon ratios of 2 at space velocities near 100,000/h⁻¹. Both catalysts were shown to have good S tolerance when tested with a fuel mixture containing 50 parts per million S in the form of dibenzothiophene. Parallel to catalyst development, the impact of fuel mixing and vaporization through improved liquid injection also is under investigation. This paper was presented at the ASM Materials Solutions Conference & Show held October 18–21, 2004 in Columbus, OH.     

Plasma spraying of lanthanum silicate electrolytes for intermediate temperature solid oxide fuel cells (ITSOFCs)

A new challenge in the field of solid oxide fuel cells (SOFCs) concerns reducing their operating temperature to 973 K. Apatite ceramics are interesting candidates for SOFC electrolytes due to their high ionic conductivity at this temperature. The present work reports on the fabrication and characterization of La₉SrSi₆O_26.5 coatings obtained by atmospheric plasma spraying with two different plasma spray powers. The microstructure and the composition of the as-sprayed and heat-treated coatings were investigated by several techniques including X-Ray Diffraction, Inductively Coupled Plasma-Atomic Emission Spectroscopy and Scanning Electron Microscopy. The open porosity of the coatings was evaluated by the Archimedean method. It was found that the as-sprayed apatite coatings were composed of an amorphous phase as well as of a crystalline apatite phase, and that they contained chemical heterogeneities resulting from Si volatilization in the high-temperature plasma. Furthermore, a heat treatment rendered it possible to obtain denser, fully crystallized apatite coatings. Ionic conductivity measurements carried out with impedance spectroscopy demonstrated that the conductivity of the apatite coatings - depending on the spraying conditions - increased with sintering.     

High-temperature electrical testing of a solid oxide fuel cell cathode contact material

The development of high-temperature solid-state devices for energy generation and environmental control applications has advanced remarkably over the past decade. However, there remain a number of technical barriers that still impede widespread commercial application. One of these, for example, is the development of a robust method of conductively joining the mixed-conducting oxide electrodes that lie at the heart of the device to the heat resistant metal interconnect used to transmit power to or from the electrodes and electrochemically active membrane. This study investigated the high-temperature electrical and microstructural characteristics of a series of conductive glass composite paste junctions between two contact materials representative of those used in solid-state electrochemical devices, lanthanum calcium manganate, and 430 stainless steel. This paper was presented at the Fuel Cells: Materials, Processing, and Manufacturing Technologies Symposium sponsored by the Energy/Utilities Industrial Sector & Ground Transportation Industrial Sector and the Specialty Materials Critical Technologies Sector at the ASM International Materials Solutions Conference, October 13–15, 2003, in Pittsburgh, PA. The symposium was organized by P. Singh, Pacific Northwest National Laboratory, S.C. Deevi, Philip Morris USA, T. Armstrong, Oak Ridge National Laboratory, and T. Dubois, U.S. Army CECOM.     

Designing sealing glasses for solid oxide fuel cells

Thermal and chemical properties of “invert” glasses and glass-ceramics developed for hermetic seals for solid oxide fuel cells are described. The glasses crystallize to form thermally stable pyro- and orthosilicate phases with the requisite thermal expansion match to the Y-stabilized ZrO₂ (YSZ) electrolyte. In addition, the glasses bond to Cr-steel substrates at 800–850 °C without forming extensive interfacial reaction products. The thermal expansion characteristics of the glass-ceramics remain essentially unchanged after 28 days at 750 °C. Compositions with lower (≤2 mol%) B₂O₃ contents exhibit the lowest volatilization rates when exposed to wet forming gas at 750 °C. This paper was presented at the ASM Materials Solutions Conference & Show held October 18–21, 2004 in Columbus, OH.     

A facile and environment-friendly method to fabricate thin electrolyte films for solid oxide fuel cells

A facile and environment-friendly method, the so-called vertical deposition (abbreviated as VD) method, is used to prepare thin yttria-stabilized zirconia (YSZ) films (≤5 μm) for solid oxide fuel cells (SOFCs). The YSZ films are self-assembled by VD process based on capillary force. The influence of experimental conditions (e.g. concentration of YSZ dispersion, deposition times, and sintering procedure) on the morphology of the films produced and thereby on the performance of SOFC devices is investigated. The single cell utilizing a 5 μm dense YSZ film as solid electrolyte achieves a high open circuit voltage of 1.05 V which remains stable at 700 °C for 4 h. The peak power density is 0.4 W cm⁻² at 800 °C for the phase inversion anode-supported fuel cell composed of an YSZ electrolyte film of 5 μm thick. The VD method developed herein is promising for preparing ultra-thin electrolyte films for SOFCs.