富锂正极材料Li[Li0.2Mn0.4Fe0.4]O2的表面包覆改性

用共沉淀法合成了富锂正极材料Li[Li0.2Mn0.4Fe0.4]O2,并对其表面进行Al2O3包覆。采用XRD、SEM和电化学测试等方法对样品进行表征。结果表明,与Li[Li0.2Mn0.4Fe0.4]O2相比,包覆改性后的Li[Li0.2Mn0.4Fe0.4]O2具有较好的电化学性能,其初始放电容量未明显降低,而循环寿命大大提高,4.0%Al2O3包覆处理的富锂正极材料经50次充放电循环后,容量衰减量在9%左右。     

Gd0.2Ce0.8O2包覆LaNi0.6Fe0.4O3-δ阴极制备及性能

应用丝网印刷和共烧结制备LaNi0.6Fe0.4O3-δ/Sc0.1Zr0.9O1.95/LaNi0.6Fe0.4O3-δ对称电池.以硝酸铈和硝酸钆为原料,柠檬酸作燃料,燃烧合成Gd0.2Ce0.8O2(GDC)包覆的LaNi0.6Fe0.4O3-δ(LNF)阴极.实验表明,在750oC工作温度下,纯LaNi0.6Fe0.4O3-δ阴极的极化电阻为0.70Ω.cm2,而21.3%(by mass,下同,如无特殊标注均为质量分数)GDC包覆的LNF-GDC复合阴极的极化电阻最小(0.13Ω.cm2),活化能最低(136.80 kJ.mol-1),故其阴极性能最佳.GDC的包覆加速了气体/阴极/电解质三相界面反应区的扩散过程,降低了阴极极化电阻.     

固相反应法制备α-LiAlO2包覆LiNi0.4Co0.2Mn0.4O2的电化学性能研究

以提高锂离子电池正极材料LiNi_0.4Co_0.2Mn_0.4O₂的循环性能为目的,以LiNO₃和Al(OH)₃为原料,采用固相反应法制备了α-LiAlO₂包覆LiNi_0.4Co_0.2Mn_0.4O₂正极材料。微观组织结构分析结果表明,包覆热处理后LiNi_0.4Co_0.2Mn_0.4O₂颗粒表面形成了一层不均匀絮状包覆物α-LiAlO₂。电化学测试表明,α-LiAlO₂包覆处理有效减缓了充放电循环过程中总阻抗的增加,改善了材料的循环性能。3wt% LiAlO₂包覆的正极材料在室温1C充放电循环100次后,平均每次衰减率由包覆前的0.19%下降到0.14%。     

Al2O3/TiH2包覆粉体的制备及其释氢性能的研究

TiH2颗粒可以作为多孔铝的发泡剂[1,2]. Al2O3包覆TiH2颗粒与未包覆的TiH2颗粒相比, 可以起到控制(延迟)其发泡的作用, 提高泡沫铝材料的孔隙均匀性. 然而, 目前采用的包覆方法是将细小Al2O3粉通过机械研磨包覆在TiH2表面[3].本文尝试采用化学法制备Al2O3/TiH2包覆颗粒, 并研究其包覆的效果. 用化学法制备Al2O3/TiH2包覆颗粒, 并用其作为多孔铝制备中的发泡剂, 此项研究在国内外尚未见报道.     

Ce0.67Zr0.33O2对CH4燃烧催化剂Fe2O3/Al2O3的改性作用

固定n(Ce)/n(Zr)比为0.67/0.33, 用共沉淀法制得一系列CeO2-ZrO2-Al2O3固溶体. 采用这些固溶体作载体, 以Fe2O3为活性组分, 用浸渍法制备了一系列催化剂. BET结果显示, 将适量Ce0.67Zr0.33O2引入到Al2O3载体中有助于催化剂保持较高的比表面积. TPR结果显示, 载体中引入适量的Ce0.67Zr0.33O2可以改善催化剂的氧化还原性能. XRD结果表明, Fe2O3在CeO2-ZrO2-Al2O3载体上呈现出良好的分散状况, 老化前后催化剂的晶相结构基本无明显变化. 特别是当载体中m(Ce0.67Zr0.33O2)∶m(Al2O3)的值为1∶2时, Fe2O3/CeO2-ZrO2-Al2O3催化剂在甲烷催化燃烧中显示出最佳的催化性能和抗高温老化性能.     

Al_2O_3包覆Ba_(0.6)Sr_(0.4)TiO_3复合粉体制备及表征

采用液相包覆法制备了Al2O3包覆的Ba0.6Sr0.4TiO3复合粉体。通过SEM,TEM,TG-DSC,XRD,XPS和ζ电位测试对包覆前后粉体的表面形貌、组织结构、等电点进行了测试和分析。结果表明:Al2O3以无定形结构成功的包覆在Ba0.6Sr0.4TiO3粉体表面,形成了Ba-O-Al、Sr-O-Al和Ti-O-Al键,Ba0.6Sr0.4TiO3颗粒的等电点由包覆前的pH=3.2增大至pH=8。     

氧化钛包覆对LiCo0.2Ni0.4Mn0.4O2结构和性能的影响

采用SEM、 XRD、 XPS、恒电流充放电等方法研究了不同量的氧化钛包覆对LiCo_0.2Ni_0.4Mn_0.4O₂结构和电化学性能的影响。结果表明，0.3mol%氧化钛包覆能显著改善LiCo_0.2Ni_0.4Mn_0.4O₂的循环性能、倍率放电能力及高截止电压(3.0～4.5 V)下的循环性。XPS数据表明氧化钛包覆能明显的抑制样品表面的氧化活性，从而减少了电极材料表面与电解液的反应，改善了LiCo_0.2Ni_0.4Mn_0.4O₂的电化学性能。     

Y2O3包覆LiCo1/3Ni1/3Mn1/3O2的电化学性能

通过在硝酸钇水溶液浸渍并焙烧的简单工艺, 在LiCo1/3Ni1/3Mn1/3O2材料表面包覆了一层Y2O3. 采用X射线衍射(XRD), 扫描电子显微镜(SEM), 透射电子显微镜(TEM), 循环伏安(CV)和恒流充放电对包覆和未包覆的LiCo1/3Ni1/3Mn1/3O2进行了测试分析. 结果表明, Y2O3包覆并没有改变LiCo1/3Ni1/3Mn1/3O2的晶体结构, 只存在于LiCo1/3Ni1/3Mn1/3O2的表面; 与未包覆的材料相比, Y2O3包覆后的材料在高电位下具有更好的容量保持率和放电容量. CV测试表明, 包覆层的存在有效抑制了材料层状结构的转变及电极与电解液的负反应.     

水热法制备LiMnPO4包覆的LiMn2O4正极材料及其改善的电化学特性

通过水热合成的方法制备了不同质量百分比的LiMnPO4包覆LiMn2O4的复合材料,并且利用XRD、拉曼光谱、SEM、TEM以及充放电测试等手段,对其结构和电化学性能进行了表征。研究表明,适当量的LiMnPO4包覆,不仅可以增加材料的可逆比容量,还可以有效提高材料在55℃下的循环特性。1wt%LiMnPO4包覆的LiMn2O4在55℃下的可逆容量为109 mAh.g-1,是其初始容量的96%。此外,1wt%LiMnPO4包覆的LiMn2O4与未包覆的LiMn2O4相比,在倍率特性上也有明显的改善。     

Ce0.67Zr0.33O2对CH4燃烧催化剂Fe2O3/Al2O3的改性作用

固定n(Ce)/n(Zr)比为0.67/0.33,用共沉淀法制得一系列CeO2-ZrO2-Al2O3固溶体.采用这些固溶体作载体,以Fe2O3为活性组分,用浸渍法制备了一系列催化剂.BET结果显示,将适量Ce0.67Zr0.33O2引入到Al2O3载体中有助于催化剂保持较高的比表面积.TPR结果显示,载体中引入适量的Ce0.67Zr0.33O2可以改善催化剂的氧化还原性能.XRD结果表明,Fe2O3在CeO2-ZrO2-Al2O3载体上呈现出良好的分散状况,老化前后催化剂的晶相结构基本无明显变化.特别是当载体中m(Ce0.67Zr0.33O2)∶m(Al2O3)的值为1∶2时,Fe2O3/CeO2-ZrO2-Al2O3催化剂在甲烷催化燃烧中显示出最佳的催化性能和抗高温老化性能.     

锂离子电池正极材料LiNi0.4Co0.2Mn0.4O2的合成、表征及电化学性能

以过渡金属乙酸盐和氢氧化锂为原料, 应用共沉淀或流变相预处理高温烧结法优化并制备出LiNi0.4Co0.2Mn0.4O2正极材料. X射线衍射技术(XRD)及Rietveld结构精修、扫描电子显微技术(SEM)、综合热分析(TG-DSC)表征结果和电化学测试结果表明, 该材料具有单一层状结构, 颗粒大小均匀, 热稳定性好, 首次放电比容量高达208.7 mA·h/g(2.0-4.6V, 0.1 C), 电化学性能优异. 非原位(ex situ)XRD测定结果表明, 材料充至高电位下发生的不可逆相变造成了材料的循环容量衰减.     

Structure Evolution and Electrochemical Performance of Al2O3-coated LiNi0.4Co0.2Mn0.4O2 During Charge-discharge Cycling

Several lithium-ion batteries of 18650-type were assembled with pristine or Al₂O₃-coated LiNi_0.4Co_0.2Mn_0.4O₂(NCM) as cathode material and mesocarbon microbeads(MCMB) as anode material. The cycling performance of the batteries was examined under 25℃ at a 2C rate within a potential range of 2.75-4.20 V. The changes of the crystal structure, the lattice parameter, the mean crystallite size, and the mean micro-strain of pristine NCM and Al₂O₃-coated NCM during the charge-discharge cycling were determined by X-ray diffraction(XRD). The results indicate that the bulk structure of Al₂O₃-coated NCM is more stable than that of pristine NCM, which leads to the better cycling performance of Al₂O₃-coated NCM compared to that of pristine NCM.     

AlF3包覆LiNi0.45Mn0.45Co0.10O2锂离子电池正极材料的结构表征和 电化学性能研究

通过共沉淀与固相反应法制备层状的LiNi0.45Mn0.45Co0.10O2, 并利用X射线衍射(XRD)和电子扫描显微镜(SEM)测定材料的结构和形貌. 在2.5～4.5 V范围内, 以0.1 C (28 mA•g－1)放电, LiNi0.45Mn0.45Co0.10O2正极材料的起始放电容量达到167.2 mAh•g－1, 但循环性能较差. 当采用AlF3包覆后, 材料的循环性能得到明显改善. 利用电化学阻抗谱(EIS)技术探索AlF3包覆对正极材料的电化学性能改善机理, 实验结果表明: AlF3包覆层能够阻止电解液对正极材料的溶解和侵蚀, 稳定其层状结构, 同时降低了电极界面阻抗. 因此AlF3包覆技术是一种改善LiNi0.45Mn0.45Co0.10O2材料电化学性能的有效方法和工具.     

Synthesis and enhanced electrochemical properties of LiNi0.6Co0.2Mn0.2O2 cathode materials via SDBS-assisted hydrothermal method

Journal of Solid State Electrochemistry - LiNi0.6Co0.2Mn0.2O2 (NCM622) materials with shuttle-like hierarchical micro architecture are prepared by sodium dodecyl benzene sulfonate (SDBS) assisted...     

放电温度对LiNi3/8Co2/8Mn3/8O2电化学性能的影响

采用X射线衍射（XRD）、X射线光电子能谱（XPS）、恒流充放电、循环伏安及交流阻抗法，研究了放电温度对LiNi3/8Co2/8Mn3/8O2的倍率特性、锂离子扩散及电荷传递的影响.结果表明， 提高放电温度可显著改善LiNi3/8Co2/8Mn3/8O2的放电容量与倍率放电性能.尽管温度升高使电荷传递活性与锂离子扩散速度都增加，但电荷传递活化能比锂离子扩散活化能大一倍多，表明电荷传递步骤是其电化学反应控制步骤.温度对其电荷传递的影响大于对锂离子扩散的影响.温度升高，电荷传递速率加快，电化学嵌入-迁出反应加速，是其放电容量与倍率放电特性显著改善的主要原因.     

湿化学法合成LiNi_(1/3)Mn_(1/3)Co_(1/3)O_2及其表征(英文)

利用琥珀酸为鳌合剂的湿化学法成功合成了一系列锂离子电池正极材料LiNi1/3Mn1/3Co1/3O2,在合成过程中改变琥珀酸与金属离子摩尔比(R)并研究了这一参数对合成LiNi1/3Mn1/3Co1/3O2材料物理及电化学性质的影响.采用热重、X射线衍射、Rietveld精修、扫描电镜以及超导量子干涉仪对反应机理、材料的结构、形貌以及磁学性质进行了详细表征.得到最佳合成条件为R=1,此时LiNi1/3Mn1/3Co1/3O2的阳离子混排度最低.此外,通过Rietveld精修得到该材料阳离子混排度的结果与通过磁学方法得到的结果定量相符,如对于在R=1条件下合成的样品,Rietveld精修结果显示其阳离子混排度为1.85%,而超导量子干涉仪的测试结果为1.80%.当充放电区间为3.0-4.3V,电流密度为0.2C(1C=160mA·g-1)时,该样品的首次放电容量为161mAh·g-1,库仑效率为93.1%,经过50次循环后,容量保持率可达91.3%.     

锂离子电池正极材料LiNi0.5Co0.2Mn0.3O2的合成及其高温容量衰减研究

采用共沉淀-高温固相烧结法合成了富镍型三元复合正极材料LiNi0.5Co0.2Mn0.3O2.恒流充放电测试表明,材料在3.0～4.4 V下0.2C放电容量达到179.2 mAh.g-1,但在55℃下经历100次充放电循环后发生急剧的容量衰减.电化学交流阻抗谱、X射线光电子能谱和原子发射光谱等实验表明,在高温高电压下,电解液与LiNi0.5Co0.2Mn0.3O2电极材料之间的副反应加剧,导致过渡金属原子溶出,该材料局域结构被破坏.同时,电极材料表面还沉积了高阻抗的LiF/MFx层,使得在电极的充放电过程中电荷转移阻抗和Li+扩散阻抗不断增加,以致电池容量急剧衰减.     

Mn_xCo_(2.5-x)Al_(0.5)O_4尖晶石型三元复合氧化物催化分解N_2O(英文)

用溶胶凝胶法制备了一组Mn_xCo_(2.5-x)Al_(0.5)O_4尖晶石型三元复合氧化物,用于有氧气氛下的N_2O催化分解反应.用N_2物理吸附、X射线衍射(XRD)、扫描电镜(SEM)、H_2程序升温还原(H_2-TPR)、O_2程序升温脱附(O_2-TPD)、X射线光电子能谱(XPS)等技术对催化剂进行了结构表征,考察了催化剂组成、母液pH、K负载量等制备参数对其催化活性的影响.结果表明:K的加入弱化了催化剂表面的金属-氧化学键,有利于表面氧物种的脱除,改性催化剂有较高的催化活性和抗水性,其中母液pH=2、K/(Mn+Co)比为0.02的K/Mn_(0.2)Co_(2.3)Al_(0. 5)O_4催化剂活性较高,该催化剂在有氧、有氧有水气氛400℃连续反应50 h,N_2O转化率分别达98.5%和76.5%.     

LiNi0.8Co0.2O2/CNTs Composite used as the Materials for Supercapacitor Electrodes

Stupercapacitors or electrochemical capacitors(ECs) have attracted considerable attentionas an intermediate power source between conventional capacitors and batteries since they possesshigh power density and energy density, exhibit excellent reversibility, and have long cycle life1.Conductive polymers2, electrically conductive metal oxide3,4, activated carbon5 and carbonnanotubes(CNTs) 6-9 have been used as supercapacitor electrode materials. LiNi0.sCo0.2O2 is apromising lithium battery material because it has some advantages of both LiNiO2 and LiCoO2besides its low cost and high power10.In this paper, the electrochemical properties of supercapacitors based on LiNi0.8Co0.2O2/carbonnanotubes composite and LiNi0.8Co0.2O2/acetylene black composite and CNTs in 1 mol/LLiClO4/EC+DEC [V(EC):V(DEC)=1:1] electrolyte have been investigated by means of constantcharge/discharge current tests. The experiment results show that the LiNi0.8Co0.2O2/carbon nanotubescomposite has better properties than others, and the maximun specific capacitance of thesupercapacitor can reach 284.88F/g, while the energy density is up to 158.27Wh/Kg.That discharge capacities, coulombic efficiencies and energy densities at the first cycle and themaximum value and capacity retention at the 100th cycle for supercapacitors using differentelectrode materials (A) LiNi0.8Co0.2O2/acetylene black, (B) LiNi0. 8Co0.2O2/CNTs, (C) CNTs is listedin table 1*Capacity retention rate obtained by dividing the discharge capacity at the 100th cycle by themaximum valueFrom above, the LiNi0. 8Co0.2O2/carbon nanotubes composite should be a good candidatesupercapacitor electrode material.     

Effect of Various Synthesis methods on the Electrochemical Properties of LiNi1/3Co1/3Mn1/3O2

Layered LiNi1/3Co1/3Mn1/3O2 has the isostructure of α-NaFeO2 and shows high rate capacity with stable cycleability. Furthermore, the thermal behavior of this material is milder than that of lithium nickel oxide and lithium cobalt oxide. In addition, it is expected to be stable at elevated temperatures. Therefore LiNi1/3Co1/3Mn1/3O2 may be the most promising cathode materials of lithium-ion secondary battery.In this research, LiNi1/3Co1/3Mn1/3O2 was prepared by solid-state reaction, sol-gel method and mixed hydroxide method. The influences of synthesis method on the physical and electrochemical properties of LiNi1/3Co1/3Mn1/3O2 were characterized by means of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), charge/discharge cycling cyclic voltammetry and differential scanning calorimetry (DSC). XPS studies show that the predominant oxidation states of Ni, Co and Mn in the LiNi1/3Co1/3Mn1/3O2 compound are 2+, 3+ and 4+. From the voltage profile and cyclic voltammetry, the redox processes occurring at ～3.8V and ～4.5V are assigned to the Ni2+/Ni3+ and Co3+/Co4+ couples, respectively. Different preparation methods result in the difference in morphology (shape, particle size and specific surface area) and electrochemical behaviors. A sample prepared by solid-state reaction has the worst electrochemical performance among these three methods. Sample synthesized by mixed hydroxide method displays the better rate capacity than that prepared by sol-gel method, while the capacity retention of sample prepared by sol-gel method is superior to that synthesized by mixed hydroxide method.