An investigation of the interfacial stability between the anode and electrolyte layer of LSGM-based SOFCs

LSGM is known to have very serious interfacial reactivity with other unit cell components even though it is one of the most favorable solid electrolytes for intermediate-temperature SOFCs. Above all, the formation of a La-deficient La-Sr-Ga-O phase at the LSGM/NiO or the LSGM/CeO₂ interface is most problematic in LSGM-based SOFCs due to the very resistive nature of its electrical property in fuel cell operating conditions. In this study, we investigated the interfacial reactions in LSGM-based SOFCs under various fabrication conditions, in order to discern a method to either avoid or diminish the undesirable influence of these interfacial reactions. Microstructural evolution due to the chemical reactions between the anode and electrolyte layer were characterized with an Environmental Scanning Electron Microscopy (ESEM-PHILIPS XL-30) and an Energy Dispersive X-ray (EDX-Link XL30) analysis. The spatial distributions of each constituent element at the interfaces were thoroughly investigated with an Electron Probe Micro-Analyzer (EPMA-JEOL. JXA-8600).     

Microstructure and ionic conductivity of Sr- and Mg-doped LaGaO3

Samples of Sr- and Mg-doped LaGaO₃ (LSGM) with various concentrations of Sr and Mg were prepared by using solid-state reaction method. Results show that ionic conductivities increase with the increase of relative densities. It can also be known that the optimized concentration in with high conductivity is LSGM1520 or LSGM2015. The results also show that, in various concentrations of LSGM, equiaxed, rode-like, polygonal secondary phases such as LaSrGaO₄ or LaSrGa₃O₇ were detected besides (La,Sr)(Ga,Mg)O₃ by means of SEM and EDX. With the increase of doped elements, i.e. x + y, the grain size increases.     

Proton and oxide-ionic conduction in Sr- and Zn-doped LaGaO3

The ionic conduction behaviors in La_0.9Sr_0.1Ga_0.9Zn_0.1O_3−α under different atmospheres at 600–1,000 °C were studied by various electrochemical methods including ac impedance, hydrogen and oxygen concentration cells, electrochemical hydrogen and oxygen pumping, etc. The proton conduction in this oxide was investigated for the first time. The hydrogen concentration cell and oxygen concentration cell showed stable electromotive forces close to the theoretical ones calculated from Nernst’s equation, indicating that the conduction was almost pure ionic under hydrogen atmosphere or dry oxygen atmosphere. The electrochemical hydrogen pumping rates coincided with the theoretical ones calculated from Faraday’s law, confirming that La_0.9Sr_0.1Ga_0.9Zn_0.1O_3−α is a proton conductor under hydrogen atmosphere. A similar result for electrochemical oxygen pumping was obtained, indicating that it is an oxide-ionic conductor under dry oxygen atmosphere. The ionic conductivity was about 0.06 S cm⁻¹ at 1,000 °C.     

微波辅助PVP溶液聚合法制备LSGM电解质粉末

采用了一种全新的化学方法(PVP溶液聚合法)成功制备出了La0.8Sr0.2Ga0.83Mg0.17O2.815粉末;研究了不同含量聚合载体(PVP)对结果的影响规律,找到了能保证金属离子在聚合网状结构中均匀分布并防止偏析的最佳的PVP含量;探索了所制备产物在不同温度下的烧结行为.与传统的Pechini法相比,本实验所需有机物聚合载体(PVP)的量更少,这也证明PVP可以作为一种制备LSGM粉末更为有效的载体.而微波具有更高的加热速率,加热时反应体系中不会存在温度梯度,使得反应更加均匀,制备的粉末杂质更少,压片烧结后其晶粒尺寸也更小(2～3μm).     

多孔硅/硅钛合金的制备及在锂离子电池负极上的应用

以钛掺杂介孔二氧化硅SBA-15为前驱体,用镁热还原法制备多孔硅/硅钛合金复合材料。采用X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)和红外光谱(FT-IR)等方法对复合材料进行表征;利用恒电流充放电对复合材料作为锂离子电池负极材料的电化学性能进行分析。结果表明,多孔结构为体积膨胀提供了缓冲空间,硅钛合金的存在起到支撑骨架的作用,同时一定程度上改善了负极材料的导电性,多孔硅/硅钛合金复合材料具有较好的循环稳定性,0.1C循环50圈后可逆容量为801mAh/g,倍率性能也较单质硅材料大大提高,1C倍率下放电容量为618.9mAh/g。     

Synthesis of Sr- and Fe-doped LaGaO3 perovskites by the modified citrate method

Fine particle strontium and iron substituted lanthanum gallates La_1–x Sr _x Ga_1–y Fe _y O_3–, where x = 0.2, 0.4, and 0.6; y = 0.2, 0.4, 0.6, and 0.8, have been synthesized by a modified citrate method. The formation of these powders was confirmed by the X-ray powder diffraction (XRD) and the fine particle of La_0.6Sr_0.4Ga_0.2Fe_0.8O_3– was investigated by scanning electron microscopy (SEM), and particle size analysis. The single phase of La_0.8Sr_0.2Ga_0.4Fe_0.6O_3–, La_0.6Sr_0.4Ga_0.2Fe_0.8O_3–, and La_0.4Sr_0.6Ga_0.2Fe_0.8O_3– powders could be obtained both with and without calcination. The amount of the secondary phase increased when the amount of Sr in La_1–x Sr _x Fe_0.6Ga_0.4O_3– was more than 0.2 (x > 0.2) and the amount of Fe in La_0.6Sr_0.4Ga_1–y Fe _y O_3– and La_0.4Sr_0.6Ga_0.2Fe_0.8O_3– was less than 0.8 (y < 0.8). The results indicated that in the pH range of 1.36–9.27, the single phase of La_0.6Sr_0.4Ga_0.2Fe_0.8O_3– was formed without calcination and the pH had negligible effects on the structure and lattice parameter. The fine particle of these calcined powders (<4 m) was obtained with the average particle size 1.70 m at pH = 1.36 and with the average particle size between 0.56–0.60 m at pH range between 3.39–9.27, and with a lattice parameter about 3.9 Å.     

锂电池负极材料氧化锡多孔疏松纳米球的制备、表征及电化学性能研究

在不使用模板和表面活性剂的前提下,利用水热法成功制备出了具有多孔疏松结构的SnO2纳米球,该球体是由无数个小的纳米颗粒组装而成的。运用X射线粉末衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)和选区电子衍射(SAED)等对所得产物的晶体结构和形貌进行了表征,同时也对其作为锂离子电池负极的电化学性能进行了系统的研究。     

Synthesis and electrochemical characterization of Si-Mn alloy anode materials for high energy lithium secondary batteries

The Si-Mn alloys as anode active materials were prepared by mechanical milling and calcination at three different temperatures like 600, 700, and 800 degrees C. The alloys were characterized by X-ray diffraction, field emission-scanning electron microscopy, field emission-transmission electron microscopy, and electrochemical cycling within a range of 2.5 V to 0.01 V versus Li/Li+. We found that the Si-Mn alloy calcined at 800 degrees C exhibited (i) an enhanced reversible capacity during the intercalation and de-intercalation process and (ii) a reduction in fading capacity characteristic due to modified structural and interfacial properties. Increasing the calcination temperature could improve the electrochemical performance of these materials, especially at 800 degrees C. Hence this alloy possibly suited to apply for lithium rechargeable batteries. The reversible capability after fourth cycling increases in the range of 95% to nearly 99% coulombic efficiency during the following intercalation and de-intercalation process. The Si-Mn alloy has the potential to be suitable for use as an anode active material in lithium rechargeable batteries.     

Synthesis and electrochemical characterization of carbon spheres as anode material for lithium-ion battery

Carbon spheres were synthesized by the thermal decomposition of RF precursor which was synthesized by surfactant-assisted polycondensation of resorcinol with formaldehyde. The morphology of precursor was preserved during the decomposition process. EDS, TG, SEM, CV and galvanostatic charge-discharge methods are used to characterize the composition, morphology, and electrochemical performance of carbon spheres. The results revealed that these carbon spheres had a spherical morphology, smooth surface and probable size of about 400 nm. When the carbon spheres were used as anode materials for lithium-ion battery, they exhibited a high lithium storage capacity and good cycle performance. In addition, the possible progress for the preparation of carbon spheres was proposed.     

A Valence Electron Structure Criterion of Ionic Conductivity of Sr- and Mg-doped LaGaO_3 Ceramics

The valence electron structures of Sr- and Mg-doped LaGaO3 ceramics with different compositions were calculated by Empirical Electron Theory of Solids and Molecules (EET). A criterion for the ionic conductivity was proposed, i.e. the 1/(nAnB) increases with increasing the ionic conductivity when x or y≤20% (in molar fraction).     

A Valence Electron Structure of Sr- and Mg-doped LaGaO3 Criterion of Ionic Conductivity Ceramics

The valence electron structures of Sr- and Mg-doped LaGaO3 ceramics with different compositions were calculated by Empirical Electron Theory of Solids and Molecules （EET）. A criterion for the ionic conductivity was proposed, i.e. the 1/（nAnB） increases with increasing the ionic conductivity when x or y〈20% （in molar fraction）.     

石墨烯负载Fe_2O_3纳米复合材料及储能性能研究

针对锂离子电池体系,以提高负极材料可逆充放电容量为目的,制备了Fe2O3-石墨烯纳米复合材料,并利用XRD、SEM对其结构和形貌进行了表征分析,通过恒流充放电测试对其电化学性能进行系统研究。采用水热法成功制备了二元的Fe2O3-石墨烯纳米复合材料,纳米Fe2O3分布较为均匀,形貌多为菱形块状或类球状多面体,且与石墨烯片相互交叠,有效抑制了双方的团聚,形成了有利于储锂的堆砌结构。电化学性能测试表明,Fe2O3-石墨烯纳米复合材料的储锂性能大大优于石墨烯和纳米Fe2O3,30次循环后,可逆容量仍高达1 252mAh/g,循环性能优异;随着石墨烯加入量的增大,Fe2O3-石墨烯纳米复合材料的可逆容量越高。     

中温固体电解质LaGaO3的制备

分别采用固相反应法、凝胶燃烧法分别制备了镓酸镧基固体电解质粉体(La0．9Sr0.1Ga0．8Mg0．2O3-δ)．讨论了煅烧温度对粉体物相的影响,比较了两种方法所制备粉体的特点．X射线衍射分析表明．固相反应法制备需经1250℃下预烧15h,1500℃下煅烧24h．得到La0．9Sr0.1Ga0．8Mg0．2O3-δ粉体颗粒尺寸在1μm,而凝胶燃烧法仅需在1400℃煅烧10h可以合成La0．9Sr0.1Ga0．8Mg0．2O3-δ粉体,粉体颗粒尺寸150nm。     

镓酸镧基陶瓷燃料电池电极材料研究进展

综述了镓酸镧基陶瓷燃料电池电极材料的研究进展,对目前广泛研究的Ni负极材料研究中存在的问题和改进研究进行了详细的介绍,评述了掺杂LaMnO3等正极材料与镓酸镧电解质的化学相容性以及今后电极材料的发展方向.     

3DOM SnO2-SiO2锂离子电池负极材料的制备及电化学性能

针对SnO2锂离子电池负极材料长循环性能差的缺点,把非晶SiO2引入SnO2材料中,形成SnO2-SiO2纳米复合材料。采用聚苯乙烯(PS)胶晶作为模板,制备出三维有序大孔SnO2-SiO2纳米复合材料。研究结果表明,3DOM SnO2材料晶体结构和3DOM SnO2-SiO2材料相似,但是加入SiO2以后,3DOM SnO2-SiO2材料的长循环性能得到显著提高。在500 mAh/g的电流密度下循环100次,此时加0%Si的3DOM SnO2-SiO2材料的充电比容量急剧衰减为147 mAh/g,加5%Si的3DOM SnO2-SiO2材料的充电比容量达654 mAh/g,此外500次循环后加5%Si的3DOM SnO2-SiO2材料充电比容量增至728 mAh/g。这些结果表明SiO2能够改善3DOM SnO2材料长循环稳定性。     

Synthesis and electrochemical properties of Co3O4 nanofibers as anode materials for lithium-ion batteries

Co₃O₄ nanofibers as anode materials for lithium-ion batteries were prepared from sol precursors by using electrospinning. The morphology, structure and electrochemical properties of Co₃O₄ nanofibers were characterized by atomic force microscopy (AFM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and charge-discharge experiments. The results show that Co₃O₄ nanofibers possessed typical spinel structure with average diameter of 200 nm. The initial capacity of Co₃O₄ nanofibers was 1336 mAhg^− 1 and the capacity reached 604 mAhg^− 1 up to 40 cycles. It was suggested that the high reversible capacity could be ascribed to the high surface area offered by the nanofibers' structure.     

电化学方法制备纳米MgTiO3及表征

以金属阳极溶解法制得MgTiO3前驱体MgTi(OCH2CH3)(6-y)(acac)y[acac为乙酰丙酮基];讨论了影响电合成镁、钛醇盐配合物的主要因素。在pH=8.5的条件下,将含有前驱体的电解液直接水解形成凝胶,凝胶经洗涤、干燥后,在500℃下煅烧2h,制得纳米Mg-TiO3粉体。采用红外(IR)、热重-差热分析(TG-DTA)、X-射线衍射(XRD)、电子透射技术(TEM)等对前驱体和纳米Mg-TiO3进行了表征。实验表明,在使用导电盐Bu4NBr浓度0.04mol/L,控制电解液温度35～40℃之间的条件下,制得的纳米Mg-TiO3粉体纯度高,平均粒径在20～30nm之间。     

铜掺杂的磷酸铁锂复合正极材料的制备和电性能研究

利用共沉淀法制备了铜掺杂的磷酸铁锂正极材料。对产物进行了XRD、SEM、FT-IR、DSC表征分析。结果表明Cu掺杂的LiFePO4具有与LiFePO4相同的单一橄榄石型晶体结构,样品粒径在0.4～20μm左右,形貌规整,粒径分布均匀。0.2C倍率下LiFePO4/C的充放电比容量达到142和144mAh/g,而LiCuxFe1-xPO4/C在充放电的比容量分别为150.1和151mAh/g。LiCuFePO4/C循环40圈后比容量保持率为97.8%,而LiFePO4/C的保持率仅为82.1%。     

二氧化锡中空球的制备及其电化学性能研究

用碳球做模板,SnCl_4·5H_2O和尿素为前驱体制备了二氧化锡(SnO_2)中空球.X射线衍射(XRD)、扫描电镜(SEM)和高分辨透射电镜(HRTEM)结果表明:制备出来的SnO_2中空球为四方相结构,其直径和壁厚分别约为250nm和40nm.恒电流充放电测试结果显示:在电流密度为160mAh·g~(-1)(0.20时,该SnO_2中空球的首次放电容量为1720mAh·g~(-1),第15周期放电容量保持到615mAh·g~(-1);从第4周期开始,库仑效率均保持在90%以上.电流密度为320mAh·g~1(0.4C)时,第15周期放电容量保持到588mAh·g~(-1).以上结果表明,这种材料具有较高的储锂容量和较好的可逆性能,是一种有前景的锂离子电池负极材料.