循环伏安沉积纳米氧化钌基超级电容器电极材料

在三氯化钌(RuCl3)水溶液中,采用循环伏安法在钽电极表面电化学沉积无定形水合氧化钌(RuO2.xH2O)作为超级电容器电极材料。能谱分析表明,在循环伏安负向扫描时Ru3+在钽电极表面还原为钌金属(Ru),沉积的Ru在随后的正向扫描时被氧化为RuO2.xH2O。扫描电镜观测显示出负向扫描沉积的Ru为纳米尺度,因而获得了纳米结构的RuO2.xH2O。由于纳米结构可以提高电极比表面积和显著缩短离子和电子的传输路径,因而获得了具有高电化学活性的RuO2基超级电容器电极材料。循环伏安、恒电流充放电和电化学阻抗谱测试证实,该电极材料在38%(质量分数,下同)的H2SO4溶液中具有接近理想电容器的容量行为,比容量高达730F.g-1(扫描速率为50mV.s-1)。在质量负载为1.2mg.cm-2时,比容量仍高达700F.g-1。另外,其容量在10万次循环后仍保持不变,充放电效率接近100%。并且该方法可以直接在钽金属基底上电化学沉积RuO2.xH2O,避免了在常规电化学沉积法中需要的预涂层。     

均匀沉淀法制备LiFePO4/C及其电化学性能

以FeSO4·7H2O、H3PO4、H2O2和尿素为原料,采用均匀沉淀法制备LiFePO4的前驱体FePO4·xH2O,研究表面活性剂PEG对前驱体FePO4·xH2O形貌的影响。并将获得的FePO4·xH2O与Li2CO3及葡萄糖混合后合成LiFePO4/C。利用XRD、SEM、循环伏安测试、电化学性能测试、交流阻抗测试等手段对LiFePO4/C进行表征。结果表明:当不添加表面活性剂PEG时,FePO4·xH2O颗粒呈球形,但团聚现象严重;添加PEG后,颗粒较分散,形貌为多面体,合成的LiFePO4/C在0.1C时的首次放电比容量为151.0 mA·h/g,倍率性能好,振实密度达1.44 g/cm3。     

金属合金化X（X=Sr、Zr、Sn、Ce）对RuAl抗氧化性能影响的计算研究

目的研究RuAl的金属合金化及其氧化物Al_2O_3和RuO_2两相组的氧化关系,揭示其抗氧化性能机理。方法采用密度泛函理论的第一性原理,建立RuAl掺杂金属原子X及其间隙添加O原子的RuAl-X-O晶胞模型与其氧化产物Al_2O_3和RuO_2的晶胞模型。结果计算的Al_2O_3和RuO_2氧化能结果显示,Al_2O_3的氧化能(-11.43 eV/O_2)比RuO_2的氧化能(-2.28 eV/O_2)小,RuO_2的氧化能值与0值较为接近,在高温下结构稳定性较差,比较容易发生分解,RuAl的抗氧化能力主要依靠氧化产物Al_2O_3来进行。金属X合金化后,RuAl的氧化产物Al_2O_3和RuO_2的氧化能都增加,氧化能差值(eV/O_2)从大到小依次为Zr(0.29)Ce(0.28)Sn(0.22)Sr(-0.49),其中,金属Zr合金化对提高RuAl抗氧化能力的效果最好。计算的氧间隙形成能和电荷密集数等结果显示,金属X原子对RuAl的合金化降低了RuAl中的O固溶度,从而导致RuAl中内氧化速度降低。结论金属X原子对RuAl的合金化,阻碍RuAl表面的O向其内部扩散,障碍"内氧化"的生成条件,在RuAl表层界面的横向方向上容易形成连续、致密的Al_2O_3氧化层,提高RuAl的抗氧化性能。     

Electrochemical and microstructural characterization of cyclic redox behaviour of SOFC anodes

The oxidation of Ni to NiO in solid oxide fuel cell (SOFC) anode will result in large bulk volume change, which may change the interfaces of the two phases in the anode cermet and thus may cause significant performance degradation. The reduction and oxidation (redox) of the Ni/YSZ cermet were studied at 800 ℃. Anodic polarization measurements were performed before and after redox cycles. The anode current density at an overpotential of 100 mV kept decreasing during the whole redox treatment. It decreased from 19.11 to 7.95 mA·cm-2 after two redox cycles. Anode supported unit cell was assembled for cell's discharge measurements. Cell performance declined after each redox cycle. The maximum power density decreased from 126.28 to 40.32 mW·cm-2 . The microstructural changes after redox cycling were recorded using scanning electron microscopy (SEM). The results reveal that after re-oxidation, the Ni gets coarse and has a higher porosity; the nickel network structure turns to be desultory.     

Solid-state synthesis and electrochemical properties of SmVO4 cathode materials for low temperature SOFCs

A new cathode material fabricated by solid state reaction method was reported. The SmVO4 powder was obtained by firing the mixture of Sm2O3 and V2O5 powders in the temperature range of 700-1200 ℃. Its structure was identified by X-ray diffraction method and the electrochemical properties of SmVO4 as cathodes for solid oxide fuel cells (SOFCs) were investigated in single unit cell at the temperature ranged from 450-550 ℃. The results of the single fuel cell unit show that the maximum current densities are 641, 797, 688 mA·cm-2 and the maximum power output are 165, 268, 303 mW·cm-2 and the open circuit voltage are 1.04,0.96,0.92Vat 450, 500 and 550 ℃, respectively.     

Influence of characteristics of stabilized zirconia electrolyte on performance of cermet supported tubular SOFCs

Ni-Al2O3 cermet supported tubular SOFC was fabricated by thermal spraying. Flame-sprayed Al2O3-Ni cermet coating plays dual roles of a support tube and an anode current collector. 4.5mol.% yttria-stabilized zirconia (YSZ) and 10mol.% scandia-stabilized zirconia (ScSZ) coatings were deposited by atmospheric plasma spraying (APS) as the electrolyte in present study. The electrical conductivity of electrolyte was measured using DC method. The post treatment was employed using nitrate solution infiltration to densify APS electrolyte layer for improvement of gas permeability. The electrical conductivity of electrolyte and the performance of single cell were investigated to optimize SOFC performance. The electrical conductivity of the as-sprayed YSZ and ScSZ coating is about 0.03 and 0.07 S·cm-1 at 1000 ℃, respectively. The ohmic polarization significantly influences the performance of SOFC. The maximum output power density at 1000 ℃ increases from 0.47 to 0.76 W·cm-2 as the YSZ electrolyte thickness reduces from 100 μm to 40 μm. Using APS ScSZ coating of about 40 μm as the electrolyte, the test cell presents a maximum power output density of over 0.89 W·m-2 at 1000 ℃.     

TiO2组元对RuO2+SnO2+TiO2/Ti阳极涂层微观结构的影响

通过溶胶凝胶(Sol-gel)过程制备了添加TiO2的RuO2 SnO2／Ti纳米涂层钛阳极，并通过X射线衍射(XRD)、差热分析(DTA)、透射电子显微镜(TEM)分析了TiO2组元对RuO2 TiO2 SnO2／Ti电极涂层的微观结构和晶粒尺寸的影响。结果表明：涂层组成物主要为(Ru，Sn，Ti)O2固溶体，在TiO2含量增加、退火温度升高时，该固溶体仍可稳定存在；添加TiO2细化晶粒的效果不显著，但随退火温度的升高，TiO2相对含量较高的涂层中晶粒长大速率较低，即TiO2具备稳定晶粒尺寸的作用；添加TiO2的涂层晶粒外观呈较理想的等轴状。     

W合金化对RuAl抗氧化性能影响的计算研究

基于密度泛函理论的第一性原理,建立Al_2O_3和RuO_2晶胞模型,计算了Ru Al合金氧化物Al_2O_3和RuO_2的氧化能,结果显示:Al_2O_3的氧化能为–11.43 e V,RuO_2的氧化能为–2.28 e V,Al_2O_3比RuO_2的结构稳定性更好。通过态密度、Bander电荷密度等分析,发现W合金化提高RuAl抗氧化性能的根本原因是:由于W对O的吸附作用,使W周围的Al-O和Ru-O成键强度降低,Al_2O_3和RuO_2的氧化能减少,从而降低其结构稳定性。其中,Al_2O_3结构稳定性降低更加明显。同时,W合金化可降低RuAl合金体系基体内部的Al_2O_3结构稳定性,阻碍生成内氧化过程的生成条件,减少了垂直于表层界面的Al_2O_3的形成,促使表层界面的横向方向上Al_2O_3氧化层的成长,形成连续性致密的Al_2O_3氧化层,提高Ru Al抗氧化性。     

固体氧化物燃料电池(SOFC)用NiMOCr金属连接体氧化行为研究

金属作为固体氧化物燃料电池(SOFC)连接体材料已成为可能并成为研究热点.本论文对SOFC用NiMoCr合金分别在SOFC阴极和阳极气氛条件下的高温氧化性能作了详细的研究.结果表明:阳极(燃料极)条件下氧化所形成的是MnCr2O4尖晶石;阴极(空气极)条件下氧化所形成的是不含Cr的致密NiMnO4型尖晶石,能有效抑制C...     

Electrochemical performance of Ti4+-doped LiFePO4 synthesized by co-precipitation and post-sintering method

Ti4+-mixed FePO4·xH2O precursor was prepared by co-precipitation method,with which Ti4+ cations were added in the process of preparing FePO4·xH2O to pursue an effective and homogenous doping way.Ti4+-doped LiFePO4 was prepared by an ambient-reduction and post-sintering method using the as-prepared precursor,Li2CO3 and oxalic acid as raw materials.The samples were characterized by scanning electron microscopy (SEM),X-ray diffractometry (XRD),electrochemical impedance spectroscopy (EIS),and electrochemical charge/discharge test.Effects of Ti4+-doping and sintering temperature on the physical and electrochemical performance of LiFePO4 powders were investigated.It is noted that Ti4+-doping can improve the electrochemical performance of LiFePO4 remarkably.The Ti4+-doped sample sintered at 600 ℃ delivers an initial discharge capacity of 150,130 and 125 mA·h/g with 0.1C,1C and 2C rates,respectively,without fading after 40 cycles.     

成分配比对RuO2-Ta2O5二元氧化物电容性能的影响

采用热分解法制备了不同Ru/Ta配比的Ti/RuO2-Ta2O5二元混合氧化物电极材料。采用X射线衍射(XRD)、循环伏安(CV)及恒流充放电测试分析了Ti/RuO2-Ta2O5电极的组织结构、伏安特性和恒流充放电性能。结果表明,随氧化钽含量的升高,RuO2-Ta2O5涂层的结晶程度逐渐下降,当Ta2O5含量≥70mol%时,RuO2-Ta2O5混合氧化物完全以非晶态结构存在。Ti/RuO2-Ta2O5电极的比电容随Ta2O5含量的增加呈现先增后减的变化趋势。在Ta2O5含量为70mol%时,电极具有较好的超电容性能,比电容达到621.2F·g-1。     

SO2大气中AZ91D镁合金的腐蚀规律

通过室内模拟实验,研究了含体积分数4×10-6SO2大气中AZ91D镁合金的腐蚀行为。利用原子力显微镜、金相显微镜和扫描电镜观察腐蚀形貌,用XRD分析腐蚀产物。AZ91D镁合金腐蚀1200h的增重变化分为2个阶段,第1阶段符合线性增加规律,第2阶段符合指数衰减规律。腐蚀过程中,β相作为阴极,α相作为阳极,在其上形成颗粒状腐蚀产物,产物不断增多蔓延,直至完全覆盖镁合金表面。同时,在这层产物的裂纹处出现大颗粒产物。腐蚀产物主要为MgO,Mg(OH)2,MgSO3·6H2O,MgSO4·6H2O,随着腐蚀时间的延长,MgO与Mg(OH)2的量减少,而MgSO3·6H2O和MgSO4·6H2O的量增加。     

Electrochemical properties of La0.8Sr0.2FeO3-δbased composite cathode for intermediate temperature SOFC

La0.8Sr0.2FeO3-δ is a new kind of cathode material for intermediate SOFC, but its electrochemical activity is relative poor for the lanthanum gallate based solid oxide fuel cell. In this paper, a novel composite cathode of La0.8Sr0.2FeO3-δ/La0.9 Sr0.1Ga0.8Mg0.2O3-δ was prepared on the LSGM electrolyte substrate by screen-printing method. The results of cathodic polarization measurements show that the overpotential decreases significantly when the composite cathode is used instead of the La0.8Sr0.2FeO3-δ single layer cathode. The cathodic overpotential of the composite La0.8Sr0.2FeO3-δ/La0.9Sr0.1Ga0.8 Mg0.2O3-δ cathode is 150 mV at the current density of 0.2 A·m-2 at 800 ℃, while the cathodic overpotential of the La0.8 Sr0.2 FeO3-δ single layer cathode is higher thaN260 mV at the same condition. The electrochemical impedance spectroscopy was employed to investigate the polarization resistance of the cathode. The polarization resistance of the composite cathode is 1.20 Ω·m2 in open circuit condition, while the value of the single La0.8 Sr0.2 FeO3-δ cathode is 1.235 Ω·m2.     

Ru-Ni-YSZ多维阳极在直接乙醇SOFC的应用研究

采用浸渍-自置换法,以Ru Cl3为添加剂,丙酮为表面活性剂,在阳极支撑SOFC的Ni-YSZ阳极上表面制备纳米Ru功能层,并制备Ru-Ni-YSZ||YSZ||Pd-Ag单电池。通过SEM,TEM,XRD对电极进行表征,发现Ru在Ni-YSZ阳极表面以及内部可以形成多维纳米花状催化层。通过测试不同沉积量和不同温度下纳米Ru层对单电池的电性能的影响。在750℃时,以乙醇为燃料,Ru沉积量为0.6%(质量分数)的燃料达到最高264 m W/cm~2。当Ru沉积量为0.4%时,燃料电池在700,750,800℃时,最大功率分别达到200、261和316 m W/cm2。在开路电压条件下,电池运行15h,没有出现下降和积碳现象。     

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.     

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.     

热分解法制备RuO2-IrO2/Ta超级电容器薄膜电极材料研究

用溶液涂刷热解法制备了RuO2-IrO2/Ta超级电容器薄膜电极材料。X射线衍射(XRD)、扫描电镜(SEM)对薄膜电极材料的结构和形貌的分析表明制备的电极材料具有纳米尺度和多孔结构。热分析表明(RuO2-IrO2).nH2O/Ta的结晶转化温度约为327℃。在频率为100 Hz时经320℃/30 min处理涂刷5层的热分解法制备的电极在浓度为37%的硫酸溶液中获得最大电容为55mF/143 mm2。     

Anodic reaction kinetics of electrowinning zinc in system of Zn(Ⅱ)-NH3-NH4Cl-H2O

The anodic reaction kinetics of zinc electrowinning was investigated on the titanium base RuO2 anode in the system of Zn(Ⅱ)-NH3-NH4Cl-H2O. The effects of stirring speed, ammonium chloride concentration and temperature on anodic reaction rate were studied through the curve measurement of potentiostatic polarization. The results reveal that the electrochemically controlled anodic reaction obeys Tafel equation and the anodic reaction order for ammonium chloride is 1. 056, with the apparent activation energy of 40.17 kJ/mol. The general equation of anodic reaction kinetics was obtained.     

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.     

镁合金微弧氧化体系中四硼酸钠的作用机理研究

利用扫描电镜、电化学工作站等分析手段,探讨了镁合金微弧氧化体系中四硼酸钠添加对膜层组织结构及耐蚀性的影响规律,分析了四硼酸钠在镁合金微弧氧化膜层形成及生长过程中的作用机理。研究发现:微弧放电发生前,(B_4O_7)~(2-)与Mg离子结合于阳极表面形成难溶于水的偏硼酸镁;随着四硼酸钠含量的增加,沉积于阳极表面的偏硼酸镁结构由3 g/L时的颗粒状逐步过渡到15 g/L的网状结构;这些具有高阻抗特性的偏硼酸镁沉积层的形成为微弧放电过程的进行构建出了合适的电场条件;微弧放电发生后,沉积于阳极表面的偏硼酸镁通过提高等脉宽恒峰值电流条件下的