Comparative experiment on layered Li（Ni1/3Co1/3Mn1/3）O2 as the alternative material for LiCoO2

This work was financially supported by the National Natural Science Foundation of China （No.50472093）.     

共沉淀法制备LaF3表面修饰LiNi1／3C01／3Mn1／302及性能研究

以LiNi1／3CO1／3Mn1／302为正极材料,采用共沉淀合成方法制备LaF3表面修饰LiNimCo1/3Mnm02正极材料,利用X射线衍射（XRD）、扫描电镜（SEM）和电化学测试等方法对合成材料的结构、形貌以及电化学性能进行表征。结果表明：经过LaF3表面修饰的LiNi1／3C01／3Mn1／302材料保持了LiNi1／3Co1／3Mn1/302层状结构,其中LaFs表面修饰量为0．59％时,在电压为2．75-4．50V范围内,以0．3mA／cm。电流密度下经恒电流充放电测试,其首次放电比容量为172．7mAh／g,经过50周充放电循环后放电比容量为163．5mAh／g,表现出较高的初始放电比容量和良好的抗过充电性能。     

Coating of LiNi1/3Mn1/3Co1/3O2 cathode materials with alumina by solid state reaction at room temperature

Alumina coated LiNi1/3Mn1/3Co1/3O2 particles were obtained by a simple method of solid state reaction at room temperature. The reaction mechanism of solid state reaction at room temperature was investigated. The structure and morphology of the coating materials were investigated by XRD, SEM and TEM. The electrochemical performances of uncoated and Al2O3-coated LiNi1/3Co1/3Mn1/3O2 cathode materials were studied within a voltage window of 3.00-4.35 V at current density of 30 mA/g. SEM, TEM and EDS analytical results indicate that the surface of LiNi1/3Mn1/3Co1/3O2 particles is coated with very fine Al2O3 composite, which leads to the improved cycle ability though a slight decrease in the first discharge capacity is observed. It is proposed that surface treatment by solid state reaction at room temperature is a simple and effective method to improve the cycle performance of LiNi1/3Co1/3Mn1/3O2 particles.     

共沉淀法制备LaF_3表面修饰LiNi_(1/3)Co_(1/3)Mn_(1/3)O_2及性能研究

以LiNi1/3Co1/3Mn1/3O2为正极材料,采用共沉淀合成方法制备LaF3表面修饰LiNi1/3Co1/3Mn1/3O2正极材料,利用X射线衍射(XRD)、扫描电镜(SEM)和电化学测试等方法对合成材料的结构、形貌以及电化学性能进行表征。结果表明:经过LaF3表面修饰的LiNi1/3Co1/3Mn1/3O2材料保持了LiNi1/3Co1/3Mn1/3O2层状结构,其中LaF3表面修饰量为0.59%时,在电压为2.75～4.50V范围内,以0.3mA/cm2电流密度下经恒电流充放电测试,其首次放电比容量为172.7mAh/g,经过50周充放电循环后放电比容量为163.5mAh/g,表现出较高的初始放电比容量和良好的抗过充电性能。     

镍离子注入Al2O3/1Cr18Ni9Ti钎焊界面成分分析

利用扫描电镜观察了镍离子注入Ａｌ２Ｏ３／１Ｃｒ１８Ｎｉ９Ｔｉ钎焊界面的形貌,并用ｘｌⅡ能谱分析仪对焊缝进行面、线和点扫描成分分析,结果表明,焊接面非常完整,在Ａｌ２Ｏ钎焊料／１Ｃｒ１８Ｎｉ９Ｔｉ相互界面处存在着元素扩散。     

锌对Li（Ni_（1/3）Co_（1/3）Mn_（1/3））O_2电极首次脱锂过程电化学性能的影响

共沉积法制备不同含锌量的锂离子电池正极材料Li（Ni1/3Co1/3Mn1/3）O2.采用交流阻抗谱分析该正极材料在首次脱锂过程中的电化学特性以及锌对电极阻抗和锂离子扩散系数的影响.电极阻抗图谱分析结果表明：3.7～4.4V为电极发生电化学反应的电位区间;锌减小了电极材料的SEI膜阻抗和电荷转移阻抗;少量固溶锌提高了锂离子在材料固相中的扩散能力.     

纳米Ni_3Al/Al_2O_3复合陶瓷的制备及性能

利用氢电弧等离子体法制备了纳米Ni3Al金属间化合物,并以此为弥散相,以氧化铝为基体,采用热压烧结工艺在1 450℃下制得纳米Ni3Al/Al2O3复合陶瓷,并研究其力学性能和微观结构。结果表明:加入纳米Ni3Al的复合陶瓷断裂韧性比纯氧化铝陶瓷有了明显提高,当加入质量分数5%纳米Ni3Al时,断裂韧性最高达12.1 MPa.m1/2。利用扫描电子显微镜观察试样的断口形貌,分析陶瓷的微观结构发现:随着纳米Ni3Al含量的增加,片状晶数量逐渐降低,说明纳米Ni3Al质量分数的加入抑制了片晶的生长。     

Modification of LiCo1/3Ni1/3Mn1/3O2 cathode material by CeO2-coating

LiCo_1/3Ni_1/3Mn_1/3O₂ was coated by a layer of 1.0 wt% CeO₂ via sol-gel method. The bared and coated LiMn_1/3Co_1/3Ni_1/3O₂ was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), cyclic voltammogram (CV) and galvanotactic charge-discharge test. The results show that the coating layer has no effect on the crystal structure, only coating on the surface; the 1.0 wt% CeO₂-coated LiCo_1/3Ni_1/3Mn_1/3O₂ exhibits better discharge capacity and cycling performance than the bared LiCo_1/3Ni_1/3Mn_1/3O₂. The discharge capacity of 1.0 wt% CeO₂-coated cathode is 182.5 mAh·g⁻¹ at a current density of 20 mA·g⁻¹, in contrast to 165.8 mAh·g⁻¹of the bared sample. The discharge capacity retention of 1.0 wt% CeO₂-coated sample after 12 cycles reaches 93.2%, in comparison with 86.6% of the bared sample. CV results show that the CeO₂ coating could suppress phase transitions and prevent the surface of cathode material from direct contact with the electrolyte, thus enhance the electrochemical performance of the coated material.     

Solid Solution Characteristics of Pb（B1/3Nb2/3）O3-bascd Composite Ceramics

The solid solution characteristics of Pb(B1/33Nb2/3)O3-based(B=Zn2+,Mg2+,Ni2+)composite ceramics prepared by two-phase mixed-sintering method were developed based on dielectric measurements.Results show that there are double dielectric peaks for PZN-based composite ceramic,implying two phases coexist.However single dielectric peak was presented in PMN-and PNN-based composite ceramics,respectively.It is indicated that obvious solid solution reaction exists during the sintering process of these two systems.The effects of B-site ion difference on the solid solution characteristics were discussed by crystal chemistry.SEM was employed to investigated the microstructures of composite ceramics.The influences of solid solution reaction on grain growth were discussed.     

ZrO2/Al2O3复合载体中ZrO2的晶相和晶粒尺寸对Ni基催化剂性能的影响

用沉积-沉淀和溶胶-凝胶等法在扩孔后的Al2O3基载体上分别制备了不同ZrO2晶相和品粒尺寸的负载型纳米ZrO2／Al2O3复合载体，并用浸渍法制备了Ni／ZrO2／Al2O3．考察了纳米ZrO2品型结构和品粒尺寸对CO2重整CH4催化剂Ni／ZrO2／Al2O3的性能影响．结果表明，四方相ZrO2（t—ZrO2）有利于提高催化剂的表面吸附性能和催化剂的稳定性，同时t-ZrO2晶粒尺寸越小，活性物种的分散度越高，催化剂的活性好．     

Ni／Al2O3催化剂催化乙醇水蒸气重整制氢的研究

为提高用于燃料电池的乙醇水蒸气重整制氢反应催化剂的活性,采用壳聚糖扩孔以Al2O3为载体,Ni为活性中心的催化剂。利用X射线衍射（XRD）、BET比表面测试手段对催化剂的结构进行了表征。考察了反应温度、水醇物质的量的比、液体进料空速等对反应的影响。结果表明,经600℃焙烧2h的催化剂,在水醇物质的量的比为3：1,液体进料空速（WHSV）为4．8h^-1,反应温度500℃时,产气量接近40mL／min,H2选择性达到68％。乙醇水蒸气重整制氢Ni／Al2O3催化剂的最佳反应温度为500～550℃,水醇物质的量的比一般控制在3：1～5：1范围内较好。     

MgO和ZrO2包覆对正极材料结构和电性能的影响

通过共沉淀法制备了前驱体Ni1/3Co1/3-xMn1/3（OH）2,然后与LiOH·H2O、不同金属氧化物（MgO、ZrO2）分别混合制备锂离子电池正极材料LiNi1/3Co1/3-xMn1/3MxO2（M=Mg,Zr）.通过X射线衍射（XRD）、扫描电镜（SEM）、高精度电池测试系统、交流阻抗对材料结构和电化学性能进行了表征。实验结果表明,包覆MgO后,材料的结构发生变化,而包覆ZrO2没有改变正极材料的结构。与无包覆的正极材料相比较,包覆ZrO2材料的首次放电量为119.07 mAhg-1,20次循环后容量保持率为92.64%,放电量仍达到110.31 mAhg-1。     

稀土助剂La2O3在CH4-CO2重整反应中的应用

采用浸渍法制备不同La2O3含量的Ni/La2O3-γ-Al2O3系列催化剂.通过固定床流动反应的方法,考察添加稀土助剂La2O3对镍基催化剂在CH4-CO2重整反应中的活性、稳定性的影响.结果表明：La2O3的加入能够有效地提高Ni基催化剂的活性和抗积炭性能,延长催化剂的使用寿命.但La2O3的负载量不宜过多,否则会使催化剂的活性降低.     

Ni/纳米Al2O3微粒复合电镀工艺的试验研究

采用复合电镀的方法在45#钢表面制备获得Ni/纳米Al2O3微粒复合镀层.利用正交试验法研究了电流密度、镀液pH值和镀液温度对Ni/纳米Al2O3微粒复合镀层性能和沉积过程的影响.结果发现,它们对镀层沉积过程及其性能都有影响,但影响的程度和规律不同.最后综合考虑各因素,制订出Ni和纳米Al2O3微粒在45#钢表面发生共沉积的较理想工艺.     

PA11/Al_2O_3涂覆汽车花键轴研究

研究了PA11/纳米Al2O3复合材料的摩擦性能。考察了纳米Al2O3含量及速率对材料摩擦系数和磨耗性能的影响,进行了涂覆花键轴的台架试验和道路行驶试验,并与尼龙11进行对比。结果表明,复合材料中纳米Al2O3为9%时材料的耐磨性能最好。SEM图片表明复合材料的磨损机理从纯PA11材料的粘着磨损转为轻微的磨粒磨损和粘着磨损。尼龙11与纳米Al2O3复合材料能明显提高花键轴的使用寿命。     

Structure and Oxidation Behavior of a Plasma Sprayed Yttrium Silicates Coated SiC-C/C with a Glass Outer Sealant from 1 573K to 1 873K

Different compositions of yttrium silicates coatings were deposited on SiC-C/C by plasma spraying and an outer borosilicate glass was applied on the yttrium silicates coatings surfaces.The structure of the multi-layer coatings was characterized by XRD and SEM analyses.High temperature oxidation behavior of the multi-layer coatings coated C/C composites was investigated.Results show that SiC/2SiO_2Y_2O_3/I.5SiO_2 Y_2O_3/SiO_2 Y_2O_3/glass multi-layer coating has better high temperature oxidation resistance,protecting carbon/ carbon composites from oxidation at 1 773 K in air for 164 h with the weight loss of 1.65%.The oxidation weight loss of the coated C/C with time accorded with parabolic rule in the temperature range 1 573 K-1 873 K; and the corresponding oxidation activation energy of the coated carbon/carbon composites is 132.2 kJ/mol.     

SiO2/Fe2O3复合颜料的制备工艺

在Fe2O3颗粒的悬浮液中以硅酸钠为硅源,稀盐酸调节反应体系的pH值,合成SiO2-Fe2O3核-壳粒子.研究Fe2O3表面包覆SiO2的影响因素,确定最优改性剂和改性条件.采用XRD、SEM对表面改性前后的Fe2O3进行表征,用酸溶率评价包膜效果.以硅酸钠作为硅源,在反应温度85℃、pH值为9~10、改性时间为2 h时,制备出SiO2-Fe2O3复合颜料.包覆后的Fe2O3的耐温性和耐酸性显著提高,干粉耐温性达到1000℃.     

La对CH_4-CO_2重整反应催化剂性能的影响

采用等体积浸渍法制备了Ni/γ-Al2O3和Ni/La2O3-γ-Al2O3系列催化剂,通过固定床反应、热重分析等方法,考察了催化剂的性能。结果表明：Ni质量分数为10%的Ni/γ-Al2O3催化剂具有较高的活性;稀土元素La的加入,提高了催化剂的抗积炭性能;在相同的反应条件下,10%Ni/3%La2O3-γ-Al2O3催化剂的积炭量比10%Ni/γ-Al2O3催化剂积炭量降低了40%,稳定性大大提高。以Ni/La2O3-γ-Al2O3催化剂中Ni质量分数10%,并且La质量分数3%为最佳,实验条件下制得的合成气CO/H2接近1/1。     

Structure and oxidation behavior of a plasma sprayed yttrium silicates coated SiC-C/C with a glass outer sealant from 1 573K to 1 873K

Different compositions of yttrium silicates coatings were deposited on SiC-C/C by plasma spraying and an outer borosilicate glass was applied on the yttrium silicates coatings surfaces. The structure of the multi-layer coatings was characterized by XRD and SEM analyses. High temperature oxidation behavior of the multi-layer coatings coated C/C composites was investigated. Results show that SiC/2SiO2 Y2O3/1.5SiO2 Y203/ SiO2 Y2O3/glass multi-layer coating has better high temperature oxidation resistance, protecting carbon/ carbon composites from oxidation at 1 773 K in air for 164 h with the weight loss of 1.65%. The oxidation weight loss of the coated C/C with time accorded with parabolic rule in the temperature range 1 573 K-1 873 K; and the corresponding oxidation activation energy of the coated carbon/carbon composites is 132.2 kJ/mol.     

Research on Surface Modification of 96 Al2O3 by Ni Ion Implantation

A matrix of 96 Al2O3 ceramics was implanted with Ni ion of different dosages and energies using a MEVVA implanter. Then metallic structures of copper were made on the implanted ceramics, by using selective electroless copper plating. In addition, the characteristics and microstructure of the implanted layer were studied by using the SEM, RBS and XPS. The results show that： 1） the implanted Ni exits as Ni^2, Ni^2＋, and Ni^3＋ in the surface of Al2O3 and metal Ni particles precipitate on ceramics during implantation; 2） the concentration of Ni submits to the Gauss distribution along the direction of implantation on the surface of Al2O3 and high Ni concentration on the surface can be obtained if the Ni is implanted with low energy and a high dosage and 3） Ni ion implantation can activate the surface of Al2O3 and induce electroless copper plating on the ceramics.