固体氧化物燃料电池电解质材料的发展趋势

本文综述了近年来用于固体氧化物燃料电池(Solid oxide fuel cells,SOFCs)的面心立方萤石型、立方钙钛矿型和磷灰石型结构电解质材料在国内外的研究进展情况,并简要介绍了SOFCs电解质薄膜制备工艺的研究情况,最后对电解质材料中低温化的发展趋势进行了展望.     

固体氧化物燃料电池的关键材料概述

固体氧化物燃料电池(SOFCs)因具有能量转换率高、燃料适应性强、环境友好和操作方便等优点,受到了人们的普遍关注,但是SOFCs的广泛应用还有待于其关键材料的进一步发展。本文系统的介绍了固体氧化物燃料电池对关键材料——电解质材料、阳极材料、阴极材料的要求及其研究现状,并提出了固体氧化物燃料电池在其关键材料方面的一些有待解决的问题。     

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.     

中低温固体氧化物燃料电池电解质研究进展

固体氧化物燃料电池的中低温化是其商业化的关键所在,而在中低温度下具有高离子电导率等优良性能的电解质材料成为当今的研究热点。本文中阐述了各种电解质的导电机理、性能和研究现状,讨论了它们的优缺点和应用,且指出了中低温电解质材料的发展方向和亟待解决的问题。     

浸渗法制备固体氧化物燃料电池复合阴极研究进展

中低温化是目前固体氧化燃料电池研究的主要方向,影响其发展的主要问题是电解质及阴极材料的研制.浸渗法制备复合阴极能够显著提高电池在中低温下的电化学性能和效率,是目前研究的热点之一.本文介绍了近年来采用具有催化活性的电极材料、贵金属、氧离子传导材料等作为浸渗剂制备复合阴极的研究现状,并对其发展方向进行了展望.     

固体氧化物燃料电池电解质制备方法的研究

固体氧化物燃料电池(SOFC)作为一种绿色能源得到了广泛关注,SOFC中关键材料是电解质,LaGaO_3基固体电解质(LSGM)不仅离子电导率高,而且在电池工作时稳定性好,因此成为了研究焦点。本文综述了制备中低温固体氧化物燃料电池电解质LSGM的三种方法,包括传统的固相反应法、高温高压法和溶胶凝胶法;介绍了各种方法的流程以及它们各自的优缺点。     

原位析出纳米合金的PrBaFe2O6-δ 基阳极构筑及其在固体碳燃料电池中的应用研究

开发高性能阳极材料对于固体碳为燃料的固体氧化物燃料电池（solid oxide fuel cells, SOFCs）的发展意义重大。本文研究了原位析出Fe以及FeNi合金的PrBaFe₂O_6-δ （PBF）基层状双钙钛矿材料在SOFCs中的应用。通过溶胶-凝胶法制备了Ni掺杂的 (PrBa)_0.95Fe_1.7Ti_0.2Ni_0.1O_6-δ （PBFTN）阳极材料。XRD表明合成的材料呈现钙钛矿结构且在阳极还原性气氛下保持稳定。XRD、SEM、TEM、XPS结果表明在还原性气氛下材料表面析出大量均匀分布的纳米金属颗粒。当采用纯的纳米活性炭为燃料时,电解质支撑型的以PBFTN为阳极的单电池在800℃下实现了698 mW·cm^-2的最大功率密度,性能十分优异,表明其是一种具有潜力的SOFCs阳极材料。     

原位析出纳米合金的PrBaFe2O6-δ 基阳极构筑及其在固体碳燃料电池中的应用研究

开发高性能阳极材料对于固体碳为燃料的固体氧化物燃料电池（solid oxide fuel cells, SOFCs）的发展意义重大。本文研究了原位析出Fe以及FeNi合金的PrBaFe₂O_6-δ （PBF）基层状双钙钛矿材料在SOFCs中的应用。通过溶胶-凝胶法制备了Ni掺杂的 (PrBa)_0.95Fe_1.7Ti_0.2Ni_0.1O_6-δ （PBFTN）阳极材料。XRD表明合成的材料呈现钙钛矿结构且在阳极还原性气氛下保持稳定。XRD、SEM、TEM、XPS结果表明在还原性气氛下材料表面析出大量均匀分布的纳米金属颗粒。当采用纯的纳米活性炭为燃料时,电解质支撑型的以PBFTN为阳极的单电池在800℃下实现了698 mW·cm^-2的最大功率密度,性能十分优异,表明其是一种具有潜力的SOFCs阳极材料。     

甘氨酸-硝酸盐燃烧法制备Ce_(0.8)Y_(0.2-x)Sm_xO_(1.9)电解质材料及其性能

采用甘氨酸-硝酸盐燃烧法合成了中低温固体氧化物燃料电池(SOFCs)的电解质材料Ce_(0.8)Y_(0.2-x)Sm_xO_(1.9)(CYSO,x=0.0～0.20)。通过热重-差热分析(TG-DSC), X射线衍射(XRD),扫描电镜(SEM)及交流阻抗技术分析材料的性能.结果表明:初始粉体经700℃煅烧2 h后形成单相的结晶性能良好的具有萤石结构晶粒尺寸约为25 nm的CYSO纳米粉体,CYSO晶格常数随Sm掺杂量的增加而增大;CYSO纳米粉体烧结性能良好,在1400℃烧结5 h后样品的相对密度均超过95.0%。电化学性能研究表明Sm、Y共掺杂能改善CeO_2基电解质材料的性能,其中Ce_(0.8)Y_(0.2-x)Sm_xO_(1.9)在800℃时电导率高达0.050 S/cm,电导活化能低至0.386 eV。因此,甘氨酸-硝酸盐燃烧法合成CYSO有利于降低烧结温度,提高纯度,改善电解质的性能。     

固体氧化物燃料电池电解质材料概述

固体氧化物燃料电池(SOFC)作为燃料电池发展的第三代产物,它具有高燃料转化率、高功率密度和环境友好等优点,被誉为一种具有广阔应用前景的技术。本文从材料特性、发展状况、存在问题和研究趋势等方面概述了几种萤石结构和钙钛矿结构的SOFC电解质材料。中低温SOFC电解质材料是未来主要研究方向,如果能解决材料的制备成本、稳定性等问题,那么中低温SOFC有望实现商业化。     

Efficient strategy to boost the electrochemical performance of yttrium stabilized zirconia electrolyte solid oxide fuel cell for low-temperature applications

Yttrium stabilized zirconia (YSZ) used as the state-of-the-art electrolyte for solid oxide fuel cells (SOFCs) requires high temperature (over 800 °C) to realize sufficient oxygen ion conductivity. Thus, the high operational temperature is the main restriction for the commercial process of YSZ-based SOFCs. To obtain decent ionic conductivity at intermediate-low temperatures, Sr-free cathode LaNiO₃ is introduced into YSZ to construct a novel LaNiO₃-YSZ composite electrolyte, which is sandwiched by two Ni_0.8Co_0.15Al_0.05LiO_2-δ (NCAL) electrodes to assemble systematical fuel cells. This device presents an excellent peak output of 1045 mW cm^-2 at 600 °C and even 399 mW cm^-2 at 450 °C. A series of characterizations indicates that the oxygen ion conductivity of the LaNiO₃-YSZ composite is significantly promoted in comparison with that of pure YSZ, and the LaNiO₃ component has certain proton conductivity after hydrogenation. Both of the two factors contributes to the superior performance of such devices at intermediate-low temperatures. Furthermore, the sharp decrease in electronic conductivity for LaNiO₃ in hydrogen atmosphere combined with Schottky junction at the anode-electrolyte interface eliminates the short-circuiting problem. Our work demonstrates that incorporating Sr-free cathode LaNiO₃ into the YSZ electrolyte is an efficient strategy to boost the performance and reduce the operational temperature of YSZ-based SOFCs.     

Operation viability and performance of solid oxide fuel cell fuelled by different feeds

The performances of solid oxide fuel cells (SOFCs) fed by different types of feed, i.e. biogas, biogas-reformed feed, methane-reformed feed and pure hydrogen, are simulated in this work. Maximum temperature gradient and maximum cell temperature are regarded as indicators for operation viability investigation whereas power density and electrical efficiency are considered as performance indicators. The change in operating parameters, i.e. excess air, fuel feed rate and operating voltage, affects both the performance and operation viability of SOFC, and therefore, these operating parameters should be carefully selected to obtain best possible power density and reasonable temperature and temperature gradient. Pure hydrogen feed offers the highest SOFC performance among the other feeds. Extremely high excess air is required for SOFC fed by biogas to become operation viable and, in addition, its power density is much lower than those of SOFCs fed by the other feeds. Methane-reformed feed offers higher power density than biogas-reformed feed since H₂ concentration of the former one is higher.     

氨燃料固体氧化物燃料电池性能研究进展与展望

氨是一种零碳燃料,也是富氢载体,具有较大储运优势。固体氧化物燃料电池(solid oxide fuel cell, SOFC)是一种清洁高效发电装置,在分布式发电、热电联供、储能调峰等领域有广阔应用前景,氨气可直接用作SOFC阳极燃料以实现高效、清洁、低成本发电。首先简介了质子传导型和氧离子传导型氨SOFC的工作原理,电解质、电极材料的选择以及氨气在阳极的分解过程。其次总结了氨SOFC的实验研究现状,以单电池最大功率密度为评价指标,综述了不同电解质/电极材料、电解质厚度、操作温度等因素下两种传导类型的氨SOFC的性能表现,并分析了造成电池性能差异的原因。之后介绍了氨SOFC当前面临的挑战,最后对氨SOFC未来研究方向、热电联供系统的应用进行了展望。     

Computational Studies for the Evaluation of Fuel Flexibility in Solid Oxide Fuel Cells: A Case with Biosyngas

The fuel flexibility of solid oxide fuel cells (SOFCs) is one of the advantages of this technology, and biosyngas produced from biomass is emerging as a new fuel. The fuelling of SOFCs with different fuels is always challenging because of the associated risks. Mathematical modeling tools are useful for predicting the operational safety constraints and designs of SOFCs that are suitable for different fuels. Using a single channel model that incorporates direct internal reforming (DIR), this work investigates the fuel flexibility of an anode‐supported intermediate temperature planar solid oxide fuel under co‐flow operation. The DIR reaction of methane, the water‐gas shift reaction (WGS) and the electrochemical reaction of hydrogen are the three reactions taken into account in this simulation work. Detailed comparisons of the gas concentrations, the current density distributions and the temperature change profiles are presented and discussed. These simulation results provide the initial data for performance analyses and safety predictions, which will be helpful for our future experimental investigations. The thermodynamic predictions of both nickel oxidation and carbon deposition are employed to check the operational safety of SOFCs fuelled with biosyngas.     

Electrochemical performance of low-temperature solid oxide fuel cells running on syngas from pyrolytic urban sludge

Low temperature solid oxide fuel cells (SOFCs) that efficiently utilize widely available hydrocarbon resources are highly desirable for cost reduction and durability purposes. In this work, SOFCs consisting of highly ionic conductive ceria-carbonate composite electrolytes and lithiated transition metal oxide symmetric electrodes are assembled and their electrochemical performances at reduced temperature (≤650 °C) are investigated using syngas fuel (44.65% H₂, 10.19% CH_4, 2.01% CO and the balanced CO₂) derived from pyrolytic urban sludge. The cell gives a peak power output of 127 mW cm^?2 at 600 °C and shows a relatively stable operation for 11 hours under constant voltage operational conditions. Though the composite electrode presents a moderately high polarization resistance toward CH₄ and CO oxidation and the electrochemical performance is highly correlated with the microstructure of ceria-carbonate electrolyte, it is interesting to see that a higher concentration of methane is obtained after the fuel cell reaction, which may suggest an alternative approach to realize the power and chemical co-generation within such a SOFC reactor. Finally, the symmetric electrode shows high resistance toward carbon deposition, possibly due to its high alkaline nature.     

An investigation of fuel composition and flow‐rate effects in a H2S fuelled sofc: Experiments and thermodynamic analysis

Hydrogen sulphide (H₂S)‐fuelled solid oxide fuel cells (SOFCs) can potentially generate useful electrical energy while disposing of H₂S, a toxic by‐product of the fossil fuel industry, on site. Experimental results from H₂S fuelled SOFCs exhibit characteristics, for example, an unusual dependence of cell performance on fuel composition and flow‐rate, which are poorly explained in the literature. In this work we: (a) present results for experiments where the composition and flow‐rates were varied for both the fuel and oxidant streams to analyse their effect on fuel cell performance, and (b) develop and use a thermodynamic analysis to help understand these experimental results. Through this work, we shed further light on two basic questions unanswered so far, (1) Why does the flow‐rate of the fuel affect the open circuit potential of the fuel cell? (2) Which of the chemical species present in the fuel is oxidised on the anode? Our experiments and analysis suggest that H₂S, and not H₂ produced from H₂S dissociation, is preferentially electro‐oxidised on the anode in our experiments. © 2011 Canadian Society for Chemical Engineering     

Solid oxide fuel cells in combination with biomass gasification for electric power generation

Biomass, a source of renewable energy, represents an effective substitute to fossil fuels. Gasification is a process that organics are thermochemically converted into valuable gaseous products(e.g. biogas). In this work, the catalytic test demonstrated that the biogas produced from biomass gasification mainly consists of H_2,CH_4, CO,and CO_2, which were then be used as the fuel for solid oxide fuel cell(SOFC). Planar SOFCs were fabricated and adopted. The steam reforming of biogas was carried out at the anode of a SOFC to obtain a hydrogen-rich fuel.The performance of the SOFCs operating on generated biogas was investigated by I–V polarization and electrochemical impedance spectra characterizations. An excellent cell performance was obtained, for example,the peak power density of the SOFC reached 1391 mW·cm~(-2) at 750℃ when the generated biogas was used as the fuel. Furthermore, the SOFC fuelled by simulated biogas delivered a very stable operation.     

Gas-tight yttria-doped barium zirconate thin film electrolyte via chemical solution deposition technique

A 500 nm thick yttria-doped barium zirconate (BZY) proton conducting electrolyte film, fabricated via a low-cost and high-throughput chemical solution deposition (CSD) technique, was sintered at a remarkably low temperature of 1000 °C, which is much lower than the typical solid state sintering temperature of minimum 1300 °C. Therefore, the detrimental issues, commonly encountered in solid state sintering, such as barium evaporation and phase separation, were not observed. Gas-tightness of the BZY film was confirmed by 8 h of stable open circuit voltage (OCV) at 1.08 V from a button fuel cell with NiO-BZY anode substrate and LSCF cathode. The application of the film is aimed at the electrolytes of intermediate to low temperature solid oxide fuel cells (SOFCs).     

Dense 8 mol% yttria-stabilized zirconia electrolyte by DLP stereolithography

Solid Oxide Fuel Cells (SOFCs) are environmentally efficient energy conversion devices, but are partially limited by the complicated fabrication procedure. In this work, dense 8 mol% yttria-stabilized zirconia (8YSZ) ceramics were successfully realized through a DLP (digital light processing) stereolithography method and the electrolyte self-supported fuel cell was also tested at 800 °C. The sintering behavior of the as-printed planar samples were investigated and a fully dense ceramic can be achieved at 1450 °C. The total conductivity of the sintered 8YSZ can reach 2.18 × 10⁻² S cm⁻¹ at a test temperature of 800 °C, which is acceptable for practical application. For the electrolyte self-supported fuel cell test, a power density of 114.3 mW cm⁻² can be achieved when Ni-8YSZ cermet and La_0.8Sr_0.2MnO₃ (LSM) were used as anode and cathode. It was demonstrated that 3D printing is a promising processing technique to build up electrolyte self-supported SOFCs with desired structure for the future development.