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研究进展

固体氧化物燃料电池(SOFC)是一种全固态燃料电池,连接体作为其中的关键组成部分,显著影响电池的性能。早期的连接体采用陶瓷材料制作,其高昂的成本和较高的电阻阻碍了电池的发展。随着电池工作温度的降低(550～800℃),金属材料取代陶瓷材料成为可能。铁素体不锈钢(FSS)凭借其低成本、良好的机械加工性能、高温下较好的耐腐蚀能力等优点,成为连接体候选材料,但其性能仍需进一步优化。本文综述了550～800℃SOFC连接体材料研究现状,重点介绍了FSS以及表面改性FSS的研究情况,比较了预氧化和各类涂层改性FSS的优缺点,并对连接体材料的研究方向进行了展望。     

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.     

等离子喷涂制备固体氧化物燃料电池电解质涂层研究进展*

等离子喷涂作为一种高性价比的涂层沉积工艺,在固体氧化物燃料电池(SOFC)电解质制备方面比传统方式更灵活、高效,尤其在大面积电解质快速成形上,表现出良好的发展潜力。介绍SOFC的工作原理和研究趋势,综述电解质材料及等离子喷涂制备工艺的研究进展,指明等离子喷涂制备SOFC电解质涂层的发展方向。研究表明:氧化钇、氧化钪稳定的氧化锆是目前商业化应用最广泛的电解质材料,其他如氧化铈基及氧化铋基电解质还须解决还原气氛下价态变化问题,而镧锶镓镁氧化物和硅酸盐电解质则需解决成分和结构稳定性问题。在制备方面,传统湿化学法的高温烧结过程难以制备金属支撑型SOFC,磁控溅射和气相沉积等镀膜技术成本高、效率低,不适合电解质大规模生产。而等离子喷涂技术具有沉积效率高,对基体热输入小,可灵活调控涂层微观结构等优势。等离子喷涂SOFC电解质还存在较大探索空间,基于前期相关工作为后续中低温电解质制备及优化提供思路,随着电解质粉末成本下降及喷涂设备迭代升级,等离子喷涂技术有望在未来成为大规模高效制备SOFC电解质涂层的重要手段。     

MNxO4-x作为ORR/OER活性位点的电催化性能研究

目前开发双功能电催化剂是解决金属-空气电池和燃料电池氧电极电化学过程缓慢及能量转化效率低等问题的重要手段之一,其中负载过渡金属单原子的氮掺杂石墨烯材料（M-N-C）被认为是最有希望替代贵金属的催化材料。研究表明M-N-C催化剂的高活性归因于其中过渡金属-氮氧配合物（MNxO4-x）的存在,为了探究MNxO4-x配位结构对材料催化性能的影响,本文基于第一性原理,通过在Fe-N-C材料中引入氧构建不同的FeNxO4-x（x = 0, 1, 2, 3, 4）配合物,研究金属原子的配位数x对氧还原反应（ORR）和氧析出反应（OER）催化性能的影响。结果表明,具有FeN4配位结构的Fe-N-C材料热力学稳定性及ORR/OER催化性能最佳。此外,本文通过变换过渡金属的种类,即锰、铁、钴、镍、铜（M=Mn、Fe、Co、Ni、Cu）,研究过渡金属的种类M对MN4催化活性的影响。研究发现,具有CoN4配位结构的M-N-C材料热力学稳定,且相较于其他MN4其ORR和OER催化性能最佳。本论文的研究结果可为调节过渡金属单原子的配位环境,设计高效双功能电催化剂提供理论参考。     

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.     

Conductivity and stability of cobalt pyrovanadate

Cobalt pyrovanadate was successfully synthesised by a solid state route and the conductivity in both oxidising and reducing environments was determined for the first time. Impedance measurements between 300 °C and 700 °C in air determined that Co₂V₂O₇ is an intrinsic semiconductor with activation energy of 1.16(3) eV. The conductivity in air reached a maximum of 4 × 10⁻⁴ S cm⁻¹ at 700 °C. Semiconducting behaviour was also observed in 5% H₂/Ar, albeit with a much smaller activation energy of 0.04(4) eV. Between 300 °C and 700 °C the conductivity ranged from 2.45 S cm⁻¹ to 2.68 S cm⁻¹, which is approaching the magnitude required for SOFC anode materials. Thermogravimetric analysis found a significant weight loss upon reduction of the compound. X-ray diffraction analysis, coupled with data from previous research, suggested compound degradation into Co_2−xV_1+xO₄, CoO and VO. The redox instability and the low conductivity lead us to the conclusion that cobalt pyrovanadate is unsuitable for utilisation as an anode material for SOFCs although the conductivity is reasonable in a reducing atmosphere.     

Fabrication and study on Ni1−xFexO-YSZ anodes for intermediate temperature anode-supported solid oxide fuel cells

Bimetal oxides Ni_1−xFe_xO (x = 0.01, 0.04, 0.08, 0.1, 0.15, 0.2, 0.4, 0.5) were synthesized and studied as anodes for intermediate temperature solid oxide fuel cells (SOFCs) based on yttria-stabilized zirconia (YSZ) film electrolyte. A single cell consisted of Ni_1−xFe_xO-YSZ anode, YSZ electrolyte film, LSM–YSZ composite cathode was prepared and tested at the temperature from 600 °C to 850 °C with humidified hydrogen (75 ml min⁻¹) as fuel and ambient air as oxidant. It was found that the cell with Ni_0.9Fe_0.1O-YSZ anode showed the highest power density, 1.238 W cm⁻² at 850 °C, among the cells with different anode composition. The promising performance of Ni_1−xFe_xO as anode suggests that bimetal anodes are worth studied for SOFCs in future.     

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.     

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.     

Synthesis and characterization of cobalt-free Ba0.5Sr0.5Fe0.8Cu0.2O3−δ perovskite oxide cathode nanofibers

The cobalt-free perovskite-oxide, Ba_0.5Sr_0.5Fe_0.8Cu_0.2O_3−δ (BSFC) is a very important cathode material for intermediate-temperature proton-conducting solid oxide fuel cells. Ba_0.5Sr_0.5Fe_0.8Cu_0.2O_3−δ nanofibers were synthesized for the first time by a sol-gel electrospinning. Process wherein a combination of polyvinylpyrrolidone and acetic acid was used as the spinning aid and barium, strontium, iron and copper nitrates were used as precursors for the synthesis of BSFC nanofibers. X-ray diffraction studies on products prepared at different calcination temperatures revealed a cubic perovskite structure at 900 °C. The temperature of calcination has a direct effect on the crystallization and surface morphology of the nanofibers. High porosity, and surface area, in addition to an electrical conductivity of 69.54 S cm⁻¹ at 600 °C demonstrate the capability of BSFC nanofibers to serve as effective cathode materials for intermediate-temperature solid oxide fuel cells.     

PtCo合金电催化剂在燃料电池氧还原催化中的研究现状与进展

质子交换膜燃料电池（PEMFC）具有高效、低温、环保等优点,是解决能源短缺和环境污染双重问题的潜在方案。然而,其阴极氧还原反应（ORR）中迟缓的动力学过程不得不依赖稀缺昂贵的Pt基催化剂,这阻碍了PEMFC技术的进一步发展和应用。为了降低成本并保证高效的催化性能,近年来研究人员已开发了多种技术策略,通过引入过渡金属与Pt合金化为主要策略之一,特别是PtCo双金属催化剂,它表现了更优异的ORR催化性能。本文综述了PtCo合金催化剂在PEMFC氧还原催化中的最新进展和现状,首先总结了催化剂组分控制、粒径调控、晶面调控、掺杂等调控策略对燃料电池催化活性的影响,其次详细介绍了最有前途的PtCo合金结构,如多面体、核壳、纳米框架、有序金属间结构等PtCo合金催化剂,并对催化剂载体研究进行了讨论,最后指出了PtCo合金催化剂在其应用中存在的挑战以及未来前景。