Structure and Electrical Properties of Ni-substituted Lanthanum Gallate Perovskites

Crystal structure, electrical conductivity and thermal expansion of materials in the system La_0.9Sr_0.1Ga_1–yNi_yO₃ (LSGN) with 0 < y 0.5 have been studied as a function of Ni content, temperature and P_{o 2}. The materials have an orthorhombic structure at low dopant content and a hexagonal structure for higher Ni content. The (P_{o 2}, T) results show increasing electronic conductivity at high P_{o 2} with increasing Ni content. At low P_{o 2} the conductivity fits a model for predominant ionic conductivity. AC impedance spectroscopy on an electron blocking cell of the form M/LSG/LSGN/LSG/M was used to isolate the ionic conductivity in the y=0.1 and 0.2 materials. The materials were found to have appreciable ionic conductivity in air with a similar magnitude and activation energy to the electrolyte materials. An analysis of the low frequency impedance of the blocking cell provided values for D at 800°C of the order of 9 × 10^–5 cm²/s. An evaluation of the so called chemical capacitance enabled determination of the electron density and mobility. The calculated electronic mobility of 3.8 × 10^–3 cm²/Vs and activation energy of 0.14 eV for the y = 0.2 material are in excellent agreement with expectations of an electronic transport model involving electron hopping within the Ni impurity band. The thermal expansion coefficients of the Ni doped materials were determined as a function of temperature and dopant level. The presence of mixed conductivity suggests that this material may be useful as an electrode for a lanthanum gallate based fuel cell or other electrochemical device.     

Performance of La0.9Sr0.1Ga0.5Ni0.5O3 as a Cathode for a Lanthanum Gallate Fuel Cell

The cathodic overpotential of a La_0.9Sr_0.1Ga_0.5Ni_0.5O₃ (LSGN) electrode on a La_0.9Sr_0.1Ga_0.8Mg_0.2O₃ (LSGM) electrolyte was studied using the current interruption technique. The electrode performance was found to be clearly superior to La_0.85Sr_0.15MnO₃ and comparable to La_0.6Sr_0.4CoO₃ in the temperature range of 700–850°C. The exchange current density is a maximum in air and is smaller in either 100% O₂ or 2% O₂ suggesting that the occupation of surface adsorption sites is important. The overpotential-current density curves suggest that charge transfer is the limiting process for high current densities. An energy dispersive spectrometry line scan did not show any significant interdiffusion of Ni ions across the electrode/electrolyte boundary.     

高温极化对Ni8-Fe2-LSGMC5复合阳极性能的影响

利用XRD、SEM及多种电化学技术,考察了高温原位极化对Ni8-Fe2-La0.8Sr0.2Ga0.8Mg0.15Co0.05O3-δ(LSGMC5)复合阳极性能的影响.高温极化改善了Ni-Fe复合阳极及电极/电解质界面的微观结构,减小了欧姆电阻和极化电阻,提高了电极的活性.极化没有改变复合阳极的物相,电极以Ni3Fe合金的形式存在.极化电流密度是决定电极性能的主要因素,在925 ℃下,随着极化电流密度由0 A/cm2增大至6 A/cm2,相应的电池在800 ℃下的最大功率密度由0.09 W/cm2增加至1.00 W/cm2.     

固体氧化物燃料电池研究进展

固体氧化物燃料电池是直接将化学能转化成电能的全固态化学发电装置,具有能量转化效率高,无腐蚀,燃料适应性强和寿命长等优点。介绍了固体氧化物燃料电池的阳极、阴极、电解质等核心部件,介绍了固体氧化物燃料电池存在的问题,并对未来发展前景进行了展望。     

固体氧化物燃料电池

本文综述了高温氧化物燃料电池的种类、结构、发展现状及应用前景。介绍了固体电解质、阴电极、阳电极，内联接材料的组成及制造工艺。     

柠檬酸盐法制备的La0.8Sr0.2Ga0.8Mg0.15Co0.05O3 夹层对阴极性能的影响

考察了在Sm0.5Sr0.5CoO3(SSC)-La0.8Sr0.2Ga0.8Mg0.15Co0.05O3(LSGMC5)/LSGMC5界面中加入柠檬酸盐法合成的LSGMC5夹层对界面的影响。考察了含不同温度焙烧的LSGMC5夹层的SSC-LSGMC5/LSGMC5/LSGMC5组合的微观结构及电化学性能。当夹层焙烧温度高于1 623 K时,夹层与电极的结合优于无夹层的电极/电解质界面,具有大的两相界面面积及三相界面长度。制备的组合的氧还原性能依赖于夹层以及电极的焙烧温度,含有1 673 K烧结夹层、1 123 K焙烧电极的样品具有最高的活性。与含固相法制备的LSGMC5夹层的样品相比,采用含柠檬酸盐法制备的夹层的组合具有更小的欧姆电阻及更高的氧还原活性。     

中低温SOFC钙钛矿型阴极材料的研究进展

阐述了钙钛矿材料的结构和渗氧特征,总结了目前中低温(400～750℃)固体氧化物燃料电池(SOFC)阴极材料钙钛矿系列ABO3型、K2NiF4型、YBa2Cu3O7-δ(YBCO)型和BiVOx型氧化物的研究现状.     

Ni-Fe-LSGMC8.5复合阳极的研究

制备并表征了Ni-Fe-LSGMC8.5复合阳极,电极中的n(Ni)∶n(Fe)分别为9∶1、8∶2、7∶3和5∶5。结果表明:复合阳极中的Ni和Fe以合金的形式存在,Fe含量的增加促进了电极的烧结,同时改变了电极/电解质界面的微观结构。当电极中的n(Ni)∶n(Fe)为8∶2和7∶3时,电极具有最高的电化学活性以及最小的欧姆电阻。当阳极中的n(Ni)∶n(Fe)为8∶2时,组成的Ni-Fe-LSGMC8.5|LSGMC5|SSC-LSGMC5电池在800℃、750℃、700℃和650℃下,最大功率密度分别达到1.20W/cm2、0.92 W/cm2、0.60 W/cm2和0.39 W/cm2。     

钙钛矿型SOFC阴极材料的研究进展

阴极是固体氧化物燃料电池(SOFC)的重要部件之一,阴极的性能对SOFC的性能(尤其是低温SOFC的性能)起着决定性的作用,阴极的界面电阻是整个电池电阻的70%～85%.ABO2型钙钛矿稀土复合氧化物是目前最普遍应用的固体氧化物燃料电池的阴极材料,钙钛矿材料的结构特点决定了该材料具有电子-离子混合导电性.对固体氧化物燃料电池阴极材料的催化机理、制备方法、复合梯度阴极进行了详细的描述,并提出了通过改善微结构来提高低温阴极材料的性能是今后发展的主要方向.     

A Strategy for Analysis and Modelling of Impedance Spectroscopy Data of Electroceramics: Doped Lanthanum Gallate

Modelling of impedance spectroscopy (IS) data of electroceramics depends critically on the correct choice of equivalent electrical circuit so that the extracted parameters have physical significance. The strategy proposed to choose the correct circuit involves analysis of IS data in several of the four complex formalisms: impedance, electric modulus, admittance and permittivity together with consideration of the frequency and temperature dependence of data and the magnitude and temperature dependence of extracted resistance and capacitance values. This is demonstrated using IS data from oxide-ion conducting La_0.80Sr_0.20Ga_0.83Mg_0.17O_2.82 ceramics over the range 182 to 280°C. Low temperature data are fitted first, to allow a full characterisation of the bulk response; some of the bulk parameters may then be fixed to enable fitting of the higher temperature data which increasingly feature lower frequency phenomena such as grain boundary impedances. The most appropriate circuit in this case is found to consist of a parallel combination of a resistor, capacitor and constant phase element (CPE) for the bulk response in series with a resistor and capacitor in parallel for a constriction resistance. The origin of the constriction resistance may be associated with the presence of plate-like LaSrGaO₄ secondary phase within the grains and/or with the presence of pores at the grain boundaries. The importance of choosing (a) the correct equivalent circuit and (b) approximately correct input values for the various circuit parameters to be fitted and refined are demonstrated.     

基于H-SOFC阴极材料的研究进展

围绕目前适用于质子导体作为电解质的固体氧化物燃料电池(H-SOFC)的阴极材料的研究进展,着重综述钙钛矿结构、LnBaCo_2O_(5+δ)系列及非钴基阴极材料在各种质子导体电解质上的电导率、热膨胀性能和电化学性能。     

固体氧化物燃料电池阴极材料的研究进展

综述了固体氧化物燃料电池(SOFC)阴极材料的性能.在钙钛矿型阴极材料中,Mn基材料具有较好的高温工作特性;Co基材料具有较好的低温催化特性和电导特性,但化学和结构稳定性差;Fe基材料具有较好的化学和结构稳定性,但低温下的催化性能尚需改进.其他结构类型的复合氧化物阴极材料的研究也在进行.     

固体氧化物燃料电池复合阴极研究

中低温(600~800 ℃)固体氧化物燃料电池是目前研究的主流。降低工作温度虽然能够解决材料选择、热应力、腐蚀等一系列问题,但是导致了阴极性能和阴极效率下降。复合阴极在某种程度上可以改善低温下阴极性能恶化的情况,降低过电位和极化电阻、界面电阻等。介绍了复合阴极的研究理论和研究方法,以及为解决这些问题所进行的阴极复合研究的现状,包括阴极材料与电解质、贵金属材料复合的研究现状,提出了今后的研究方向及应解决的问题。     

Ceria-Zirconia Composite Electrolyte for Solid Oxide Fuel Cells

Ceria-zirconia-ceria sandwich structured composite filmelectrolytes were designed in order to offer high ionic and low electronicconductivity electrolyte films. Calculation of oxygen potential profile inthe composite film electrolyte indicates that a very thin zirconia filmkills the electronic current of ceria without affecting the ionicconductivity. The composite films were successfully prepared by a co-fireprocess. The main problem was the fact that the ceria and zirconia greenfilms had different shrinkage behaviors. Successful co-firing was achievedby controlling the temperature program and amount of binder. De-laminationbetween yttria stabilized zirconia(YSZ) and gadolinia doped ceria(GDC)layers was overcome by the formation of a solid solution phase at theinterface of the two films. The resultant composite films, however, showedpoor electrical conductivity compared with theoretical values. The formationof a solid solution phase can have a negative effect on compositeelectrolytes. Also, the composite film is unsatisfactory in terms ofmechanical strength. This could be due to the lattice expansion in reducingatmospheres, thermal expansion coefficient mismatch, or the intrinsicweakness of the ceria texture.     

日本燃料电池的发展状况

简要地概述了日本燃料电池的发展状况。因燃料电池两电极中均含有贵重金属 (铂 钌 )作催化剂 ,大部分情况需要防止其对一氧化碳的中毒失效。如果含有碱性电解质 ,要考虑除去二氧化碳。碱性燃料电池开发较早 ;高分子电解质燃料电池在家庭及动力电源的应用上取得很大进展 ;磷酸型燃料电池已广泛应用于供电、供热 ;熔融碳酸型燃料电池则非常适合于大规模及高效率的电站应用 ;固体氧化物燃料电池的重点集中于平面基材的研究 ,以降低成本 ,适合大规模生产。在各种燃料电池的研究开发上 ,不单只是利用燃料来发电 ;更重要的是使能源得到合理的充分利用。通过对上述五种燃料电池的性能比较 ,分析了它们今后的发展方向     

固体氧化物燃料电池研究--10%Cu-Ce0.15Zr0.85O2作阳极材料

以10%Cu-Ce0.15Zr0.85O2为阳极、Pt为阴极和参考电极,组装了固体氧化物燃料电池(SOFC)单电池并进行了测试,考察了操作温度、甲烷流量等对电池性能的影响,发现提高操作温度以及在阳极材料中添加CeO2可以显著改善电池性能。升高温度,阳极极化曲线中的极限电流密度值随之上升;阳极中CeO2含量为10%时,功率最大值由未加时的4.10 mW/cm2增大至9.76 mW/cm2,对应的电流密度由12.22 mA/cm2增大至35.7 mA/cm2。甲烷的流量对电池开路电位有显著的影响,但当甲烷流量在18 mL/min以上时,其影响已十分微弱。     

SOFC用钙钛矿型质子传导固体电解质

钙钛矿型高温质子导体BaCeO3、SrCeO3和MZrO3在纯H2气氛中为纯质子导体,但在SOFC工作条件下,有些表现为质子、氧离子,甚至电子的混合导体,有些质子导体在CO2气氛中的化学稳定性较差.通过掺杂和化学计量比的控制,这些问题可以得到改善.介绍了钙钛矿型质子导体SOFC的工作原理、质子传输机理及SOFC用电解质的性能.     

用于燃料电池的氧化锆薄膜制备方法进展

固体氧化物燃料电池(SOFC)具有高效率、低污染等优点,氧化钇稳定氧化锆(YSZ)是目前用于SOFC的最成功的电解质材料,为了减小高温运行带来的困难,应用中需将YSZ制成薄膜。综述了制备YSZ 薄膜的各种方法,其中包括化学气相沉积(CVD)、电化学气相沉积(EVD)、溶胶-凝胶法(Sol-gel)和喷雾热解法等化学方法;物理气相沉积技术(PVD)和喷涂技术等物理方法;以及电泳沉积法(EPD)、注浆成型法和离心浇铸法等陶瓷成型方法,介绍了近年来采用上述方法制备的YSZ膜的性能及其用于SOFC电池研究取得的实验结果,最后评述了这些方法各自的特点。     

La1-xCaxCrO3对硫-氧燃料电池催化性能的研究

通过共沉淀法制备出La1-xCaxCrO3(x=0,0.1,0.2,0.3)作为阳极催化剂,分别以钇稳定氧化锆(YSZ)粉体和La0.66Sr0.4Co0.2Fe0.8O3-x(LSCF)粉体作为硫-氧燃料电池的电解质材料和阴极材料.发现在700～800 ℃时,La1-xCaxCrO3(x=0,0.1,0.2,0.3)...     

SOFC复合阴极的研究进展

复合阴极可以提高固体氧化物燃料电池(SOFC)在高温下的性能和效率,降低过电位、极化电阻和界面电阻。对LSM、LSCF和贵金属复合阴极的机理、电化学性能进行了研究。此类复合阴极的综合性能均得到改善,但对微观结构仍需进一步研究。