Effects of Al doping on the electrochemical performances of LiNi0.83Co0.12Mn0.05O2 prepared by coprecipitation

The Ni-rich LiNi_0.83Co_0.12Mn_0.05O₂ (NCM83) cathode materials have drawn intensive attention due to the high energy density and low cost. However, Ni-rich LiNi_1-x-yCo_xMn_yO₂ still has the fatal weakness of poor cycle stability, limiting its further wide application. Bulk doping is an effective means to enhance the cycle stability, yet the electrochemical performances are very sensitive to the doping quantity. Here a facile method of co-precipitation is adopted to coat (Ni_0.4Co_0.2Mn_0.4)_1-xAl_x(OH)_2+x on precursor particles of NCM83. Al ions diffuse evenly in the NCM83 particles after sintering. The cells are operated at a high cut-off voltage of 4.5 V. The discharge capacity of NCM83 is 187.8 mAh g^?1, and decays fast with cycles. The doped sample even exhibits a higher discharge capacity of 195 mAh g^?1, and the capacity retention is improved to 83.8% after 200 cycles.     

沉淀型Ni-La_2O_3/ZrO_2催化剂上CO_2甲烷化性能的研究

采用并流共沉淀法将不同量的稀土氧化物La2O3添加到Ni/ZrO2催化剂中,进行了XRD、TPR分析测试。结果表明,添加一定量的La2O3使催化剂的晶体结构发生变化,产生了新的物种,从而使催化剂表面改性,提高了NiO的分散度,有利于活性中心的形成,并且降低了催化剂的还原温度,当n(La)∶n(Ni)∶n(ZrO2)=0 4∶1∶1时效果最好;考察了反应温度和空速对CO2转化率的影响,在反应温度较低时,由于受到反应动力学的限制,CO2的转化率较低。     

新型功能材料:磁性固体超强酸SO2-4/ZrO2-MgO-Fe3O4的合成及表征

利用化学共沉淀法将磁性基质与固体酸组装制备磁性纳米固体超强酸,借助XRD、TEM、HRTEM、TG-DSC、VSM等手段对样品进行表征.结果表明:MgO的掺杂及磁性基质的引入延缓了ZrO2由T-ZrO2向M-ZrO2转化的趋势;样品粒径分布均匀,平均为30nm;HRTEM显示T-ZrO2晶体生长取向于[101]方向,晶面间距d(101)=0.29 nm;磁性基质的引入赋予了固体超强酸以超顺磁性;Hammett指示剂法测得经800℃焙烧后产物的酸强度H.＜-13.8,酸性大于浓硫酸(Ho=-11.93).     

Ce0.8Sm0.1Gd0.1O1.9电解质的制备及其性能研究

采用共沉淀法合成了Sm、Gd共掺杂CeO2的Ce0.8Sm0.1Gd0.1O1.9（SGC）电解质粉末。研究了工艺条件等对粉末的相组成、结构、颗粒大小的影响。并对SGC烧结体的性能进行了研究。实验结果表明,共沉淀法成功制备出的SGC电解质粉末有良好的烧结性,1 400℃下得到的SGC烧结体的相对密度大于93%。电性能测试表明烧结体在中温范围内具有较高的氧离子电导率。     

Dy_2O_3掺杂对钛酸锶钡陶瓷结构性能的影响

采用草酸盐沉淀法,以硝酸锶、硝酸钡、钛酸丁酯和草酸为原料,Dy2O3为掺杂剂,制得了Ba0.6Sr0.4TiO3粉体,并于1250℃将其烧结成Ba0.6Sr0.4TiO3系电介质陶瓷。利用扫描电镜、X射线衍射及TH2818自动元件分析仪对Dy2O3掺杂量为0.2%~2%的Ba0.6Sr0.4TiO3陶瓷的微观结构和介电性能进行研究。结果表明,Dy2O3的掺杂没有影响到BST陶瓷的主晶相钙钛矿结构,且一定量的Dy3+进入到BST晶格中。BST陶瓷的介电损耗随着掺杂量的增加而逐渐减小,介电常数随着掺杂量的增加呈现先增大后减小的趋势,当掺杂量为0.5%时,介电常数最大,为4 474.48。     

共沉淀法制备PDP荧光粉Y0.95Eu0.05AlO3

以氯化物为原料,氨水和碳酸氢铵作复合沉淀剂,采用共沉淀法合成Y0.95Eu0.05AlO3荧光粉.利用电子扫描电镜以及真空紫外激发下的发射光谱对其进行表征.结果表明,共沉淀法合成的Y0.95Eu0.05AlO3荧光粉粒径约为5μm,粒度较均匀,在真空紫外线147 nm激发下的发射主峰位于615 nm处.     

铜铈钛复合氧化物的制备及其催化一氧化碳氧化反应的性能

采用共沉淀法制备了不同钛含量的铜铈钛复合氧化物催化剂（Cu0.1CCe0.9-xTixO2,X=0～0．3）,采用微反-色谱评价装置考察了Cu0.1Ce0.9-xTixO2催化CO氧化反应的活性,并采用氮吸附／脱附,X-射线衍射以及程序升温还原等技术对催化剂进行了表征。结果表明,适量Ti（X≤0．15）的加入,提高了Cu0.1Ce0.9-xTixO2催化剂中CuO的分散度,从而提高了其催化活性。而当Ti含量过高（X=0．3）时,Cu0.1Ce0.9-xTixO2催化剂中CuO的分散度反而降低,从而导致其催化活性显著降低。     

铜基甲醇合成催化剂的研究

研究了制备工艺和不同前驱体作原料对所制备的Cu／ZnO／Al2O3甲醇合成催化剂活性的影响。结果表明，改进型并流共沉淀法制备的催化剂的活性要比传统并流共沉淀法制备的催化剂高。铜和锌都以醋酸盐代替硝酸盐制备的催化剂，可以提高铜锌组分的分散和铜锌协同作用，因而提高了活性。催化剂TPR研究表明，改进型并流共沉淀法制备的催化剂还原温度要比传统方法制备催化剂低约30℃，不同前驱体的催化剂的还原存在一定差异。另外，考察了不同升温速率下催化剂TPR的差异。     

Synthesis and electrochemical characterization of LiNi0.78Co0.2Al0.02O2 cathode material in a novel co-precipitation method

LiNi0.78 Co0.2 Al0.02O2 cathode materials were prepared with a novel co-precipitation method followed by heat-treating. The properties of the materials were characterized. XRD patterns showed that no secondary phase appeared and the hexagonal lattice parameter c of LiNi0.rsCoo.2AI~0202 was larger than that of LiNi0.8Co0.2O2. The SEM images indicated that the powders of the material were submicron size. The results of the ICP-AES analysis proved that elemental compositions of the material were similar to those of the targeted one. Cyclic voltammetry （3.0- 4. 2 V） illustrated that the new material had good lithium-ion intercalation/de-intercalation performance. The results of galvanostatic cycling showed that the initial specific discharge capacity of the prepared material was 181.4 mAh/g, and the specific discharge capacity was 177.3 mAh/g after 100 cycles （0. 2C, 3.0 - 4. 2 V, vs. Li^＋/Li） with the capacity retention ratio of 97.7%.     

Synthesis and characterization of Li1.05Co0.3Ni0.35Mn0.3M0.05O2 (M=Ge,Sn)cathode materials for lithium ion battery

In order to improve the electrochemical performance and thermal stability of Li_1.05Co_1/3Ni_1/3Mn_1/3O₂ materials,Li_1.05Co_0.3Ni_0.35Mn_0.3M_0.05O₂（M=Ge,Sn）cathode materials were synthesized via co-precipitation method.The structure,electrochemical performance and thermal stability were characterized by X-ray diffraction（XRD）,charge/discharge cycling,cyclic voltammetry（CV）,electrochemical impedance spectroscopy（EIS）and differential scanning calorimetry（DSC）.ESEM showed that Sn-doped and Ge-doped slightly increased the size of grains.XRD and CV showed that Sn-doped and Ge-doped powders were homogeneous and had the better layered structure than the bare one.Sn-doped and Ge-doped improved high rate discharge capacity and cycle-life performance.The reason of the better cycling performance of the doped one was the increasing of lithium-ion diffusion rate and charge transfer rate.Sn-doped and Ge-doped also improved the mateials thermal stability.