碳酸盐共沉淀法合成LiNi1/3Co1/3Mn1/3O2及其电化学性能

以碳酸盐共沉淀法合成了Ni1/3Co1/3Mn1/3CO3前驱体,然后以Ni1/3Co1/3Mn1/3CO3和LiOH·H2O为原料,合成出了层状锂离子电池正极材料Li Ni1/3Co1/3Mn1/3O2.通过XRD,SEM和电化学测试对Li Ni1/3Co1/3Mn1/3O2材料的结构、形貌及电化学性能进行了测试和表征.结果表明,800℃烧结12 h所合成的样品粒度大小分布比较均匀,以0.2 C充放电,其首次放电容量为153 mAh·g-1,循环30次后容量为140 mAh·g-1.     

熔盐法合成LiMn_（1/3）Ni_（1/3）Co_（1/3）O_2及AA电池的电化学性能

以KCl为熔盐,采用熔盐法合成了锂离子电池正极材料LiMn1/3Ni1/3Co1/3O2,扫描电子显微镜（SEM）显示此方法制备产物具有较好的晶形,颗粒较均匀.XRD表征结果显示产物为层状结构,充放电测试结果显示出材料在3.6 V平台附近有较大的可逆容量.在900℃时保温8 h时合成的LiMn1/3Ni1/3Co1/3O2具有较好的电化学性能,制作成AA电池,在2.75～4.2 V之间进行充放电测试,在1 C倍率下放电,LiMn1/3Ni1/3Co1/3O2的初始放电容量可达132.9 mAh/g,循环50多次后容量仍为124.6 mAh/g,容量保持率为93.75﹪.     

非均匀沉淀法包覆合成LiNi0.9 Co0.07 Mn0.03O2锂离子正极材料

采用非均匀沉淀法包覆合成了LiNi0.9Co0.07Mn0.03O2锂离子正极材料.前驱体合成中各工艺条件与包覆材料的比表面积和电化学性能息息相关.试验研究了沉淀剂、搅拌速度、pH值和氨水浓度对包覆沉淀的影响及煅烧过程对材料电化学性能的影响.结果表明:在优化实验条件下Co/Mn复合包覆在β-Ni(OH)2表面上;正极LiNi0.9Co0.07Mn0.03O2首次放电容量为195mAh·g-1,50次循环后容量仍保持为188.6mAh·g-1.循环伏安研究表明:与LiNiO2相比,Co/Mn复合包覆合成正极材料LiNi0.9Co0.07Mn0.03O2的相变得到很好的抑制,材料显示出良好的循环性能.     

熔盐法合成LiMn1/3Ni1/3Co1/3O2及AA电池的电化学性能

以KCl为熔盐,采用熔盐法合成了锂离子电池正极材料LiMn1/3Ni1/3Co1/3O2,扫描电子显微镜(SEM)显示此方法制备产物具有较好的晶形,颗粒较均匀.XRD表征结果显示产物为层状结构,充放电测试结果显示出材料在3.6 V平台附近有较大的可逆容量.在900℃时保温8 h时合成的LiMn1/3Ni1/3Co1/3...     

一维纳米LiNi1/3Co1/3Mn1/3O2纤维的合成及性能研究

通过静电纺丝法制备出一维纳米LiNi1/3Co1/3Mn1/3O2纤维,根据扫描电子显微镜(SEM)、X射线衍射(XRD)、充放电实验,循环伏安法和交流阻抗法对纳米纤维的形貌、晶体结构和电化学性能进行研究.结果表明,纳米纤维的直径在150～300 nm之间,且具有典型的α-NaFeO2层状结构;所制备的LiNi1/3Co1/3Mn1/3O2纳米纤维在0.5 C(85 mA/g)的倍率下循环30次容量保持率达到了94.1％;在倍率分别为0.1 C、0.2 C、0.5 C、1.0 C、2.0 C和0.2 C的充放电测试中,其比容量分别达到了157 mAh/g、144 mAh/g、134 mAh/g、125 mAh/g、115 mAh/g和141 mAh/g;在CV和EIS测试中,材料表现出优异的可逆性和循环稳定性.由于具有特殊的一维形貌,LiNi1/3Co1/3Mn1/3O2纳米纤维表现出优异的电化学性能.     

LiNi0.6Co0.1Mn0.3O2正极材料的合成与性能

采用共沉淀-高温固相法制备LiNi0.6Co0.1Mn0.3O2锂离子正极材料,并使用X 射线衍射仪（XRD）和扫描电镜（SEM）技术分别表征其结构和形貌.然后将所得LiNi0.6Co0.1Mn0.3O2正极材料组装成扣式电池,并表征其电化学性能,探讨烧结温度和锂配量对其电化学性能的影响.结果表明：所得LiNi0.6Co0.1Mn0.3O2正极材料的放电比容量随烧结温度的升高而增大,且在900℃时表现出最佳的电化学性能.室温下,1C倍率下,锂配量(n(Li)/n(Ni+ Co+ Mn)=1.09)时,正极材料的首次放电容量为143.7 mAh/g,50次循环后,正极材料的放电比容量仍有141.3 mAh/g,容量保持率为98.3%.     

Si4+掺杂对富锂Li[Li0.15Mn0.575Ni0.275]1-xSixO2材料性能的影响

利用共沉淀合成的锰镍氢氧化物前躯体,采用Si掺杂合成Li[Li0.15Mn0.575Ni0.275]1-xSixO2(0≤x≤4%)正极材料.用X射线衍射和扫描电镜对合成的粉末样品进行了表征,研究了材料的电化学性能.通过掺杂样品的晶胞参数及电化学性能研究发现:少量的Si4+掺杂可有效提高材料的循环性能;随掺杂量的增大,晶格畸变增大,半高宽变大;其中掺量x=1%的材料电化学性能最佳,4.2 V首次放电容量为146.7 mAh/g,经200次循环放电容量仍保持在135.7 mAh/g,容量保持率为92%.     

LiNi1/3Co1/3Mn1/3O2正极材料的合成与性能

采用共沉淀-高温固相法制备LiNi_1/3Mn_1/3Co_1/3O₂正极材料,利用XRD和SEM对所制试样的晶体结构和形貌进行表征,研究了烧结温度对材料电化学性能的影响.结果表明,焙烧温度为850 ℃制备的材料具有较好电化学性能,在25 ℃,电压范围为2.75~4.2 V,1 C充电6 C放电下首次放电比容量为124.2 mAh/g,50次循环后容量保持率为95.2 %.      

喷雾干燥法合成锂离子电池复合正极材料xLiFePO4.yLi3V2(PO4)3及性能研究

采用喷雾干燥和高温固相法合成了一系列xLiFePO4·yLi3 V2( PO4)3复合正极材料.电化学测试结果表明,0.95LiFePO4·0.05Li3 V2( PO4)3复合正极材料具有较高的比容量、优良的循环性能和倍率性能,在电压范围为2.0V～4.3V,0.1C,1C,5C条件下的放电容量分别为162.7,147.7和122.3 mAh·g-1.0.5LiFePO4·0.5Li3 V2(PO4)3和0.3LiFePO4·0.7Li3 V2 (PO4)3复合正极材料则表现出了良好的倍率性能,5C,10C充放电条件下容量保持率分别为:77％,73％,88％,82％.     

改进方法合成钛掺杂锂离子电池三元正极材料

采用改进溶胶-凝胶法合成了具有良好的晶体结构和电化学稳定性的正极材料Li[Ni1/3Co1/3Mn1/3]0.9Ti0.1O2,通过优化前驱体的制备来提高原子混合程度,从而达到改善材料循环稳定性的目的。XRD测试表明,样品的Li+/Ni2+混排程度很低,TEM图片显示材料的结晶度很高,原子排列有序,这有利于实现更大的锂离子扩散系数。在0.5 C倍率下循环200次后,材料的容量保持率高达84.6%,与未掺钛的LiNi1/3Co1/3Mn1/3O2仅为52.0%相比,钛掺杂的材料表现出优异的电化学性能。此外,掺钛材料在0.1、0.2、0.5、1.0、2.0和5.0 C时具有更好的充放电倍率性能,分别为164.9、162.4、152.4、142.4、129.7和102.8 mAh/g。研究成果可以为设计具有更好电化学性能的锂离子电池材料提供参考。     

Anisotropic Magnetoresistance of Perovskite La_(2/3)Ca_(1/3)MnO_3/YBa_2Cu_4O_8/La_(2/3)Ca_(1/3)MnO_3 Trilayer Films

Magneticanisotropyhasbeenfoundinmanyex oticmaterials,suchasmetallicsuperlatticeswithgi antmagnetoresistanceeffectsandthehightempera turesuperconductingoxideYBa2Cu3O7 δ[1～4].The anisotropycouldfindnovelusesinnewdeviceappli cations.Agoodexampleisthehig…     

Enhancement of La_2O_3 to Li-Mn/WO_3/TiO_2 for oxidative coupling of methane

A series of La_2O_3-promoted Li-Mn/WO_3/TiO_2 catalysts were prepared by varying the concentration of La_2O_3 promoter.The effect of La_2O_3 promoter on its properties and catalytic performance for OCM was characterized with XRD,FT-IR,O_2-TPD,Raman,CO_2-TPD,H_2-TPR,XPS and CH_4-TPSR,The results show that all the La_2O_3-promoted Li-Mn/WO_3/TiO_2 catalysts possess a larger amount of strong basic sites and more abundant chemisorbed oxygen species in comparison with Li-Mn/WO_3/TiO_2,which is beneficial to OCM reaction.Furthermore,La_2O_3 promoter can enhance the mobility of the oxygen species and the Mn species redox ability,which can also be favorable for the improvement of the catalytic performance for OCM,Due to the optimal synergistic interaction of these factors,5 wt%La_2O_3-Li-Mn/WO_3/TiO_2 exhibits the best performance among all the catalysts,on which the highest C_2 yield of 19.2% is achieved at 750℃.     

Al2O3La2O3Y2O3/Cu复合材料的电弧侵蚀特性研究

采用喷射沉积和内氧化法制备出Al₂O₃La₂O₃Y₂O₃/Cu复合材料,研究该材料在直流20 V/20 A的工作条件下触点的电弧侵蚀特性,并与Al₂O₃/Cu材料进行了对比分析.利用电子天平、扫描电镜等方法分析电弧侵蚀后触点的质量变化和表面微观结构.结果表明,通过添加Y₂O₃、La₂O₃稀土氧化物颗粒,可有效降低触头材料的材料转移量.Al₂O₃La₂O₃Y₂O₃/Cu材料的抗熔焊性和抗烧损性优于Al₂O₃/Cu材料的性能.在直流阻性负载条件下Al₂O₃La₂O₃Y₂O₃/Cu阳极触头表面形成凹坑,阴极触头表面形成凸起,触点表面显示出浆糊状凝固物和喷发坑等电弧侵蚀形貌特征.      

CaO-La2O3-B2O3-Eu2O3转光玻璃的合成及荧光性质

X射线衍射研究表明CaO-La2O3-B2O3-Eu2O3体系的玻璃化温度在1025℃附近.荧光光谱和ESR谱研究表明,在CaO-La2O3-B2O3-Eu2O3玻璃体系中存在着Eu2+和Eu3+两种价态离子. 316, 360, 379, 394, 413, 462和532nm锐线激发峰和592,616和650红区发射峰分别对应Eu3+的f-f激发跃迁和5D0-7FJ (J=1,2,3)跃迁发射;351nm和427nm宽带激发峰和蓝区发射分别对应Eu2+的5d-4f激发跃迁和发射.     

Wettability of silicon carbide ceramic by Al2O3/Dy2O3 and Al2O3/Yb2O3 systems

Wettability is an important phenomenon in the liquid phase sintering of silicon carbide (SiC) ceramics. This work involved a study of the wetting of SiC ceramics by two oxide systems, Al₂O₃ /Dy₂O₃ and Al₂O₃ /Yb₂O₃, which have so far not been studied for application in the sintering of SiC ceramics. Five mixtures of each system were prepared, with different compositions close to their respective eutectic ones. Samples of the mixtures were pressed into cylindrical specimens, which were placed on a SiC plate and subjected to temperatures above their melting points using a graphite resistance furnace. The behavior of the melted mixtures on the SiC plate was observed by means of an imaging system using a CCD camera and the sessile drop method was employed to determine the contact angle, the parameter that measures the degree of wettability. The results of variation in the contact angle as a function of temperature were plotted in graphic form which showed that the curves displayed a fast decline and good spreading. All the samples of the two systems presented final contact angles of 40° to 10° indicating their good wetting on SiC in the argon atmosphere. The melted/solidified area and interface between SiC and melted/solidified phase were evaluated by scanning electron microscopy (SEM) and their crystalline phases were identified by X-ray diffraction (DRX). The DRX analysis showed that Al₂O₃ and RE₂O₃ reacted and formed the Dy₃Al₅O₁₂ (DyAg) and Yb₃Al₅O₁₂ (YbAg) phases. The results indicated that the two systems had a promising potential as additives for the sintering of SiC ceramics.     

Catalytic Synthesis of Tert-Butyl Acetate by Nd2O3/Al2O3-Nd2O3/ZnO

Nd2O3 was used to support Al2O3 and ZnO to prepare a supported solid base catalyst and investigate the effect of catalyst and reaction conditions on the synthesis of tert-butyl acetate. The composited oxide of Nd2O3/Al2O3-Nd2O3/ZnO exhibited excellent catalytic activity for the synthsis of tert-butyl acetate. The molar ratio of tert-butanol to acetic anhydride is 31, the catalyst in total amount of reactant nearly 0.5%, and reaction time 6 h. With the above conditions, yield of the reaction could reach to 65%. The structure of product were verified by the FT-IR, Element analysis, and MS, which proved that the product was tert-butyl acetate.     

Ln2O3／Al2O3催化合成内增塑剂DOM

采用共沉淀焙烧法制成的Ｌｎ２Ｏ３／Ａｌ２Ｏ３ 担载型催化剂,由于比表面大,分散性好,在催化合成ＤＯＭ 中效果明显。