锂离子蓄电池正极材料层状锰酸锂的制备研究

介绍了通过水合-高温法合成的掺杂型的锰酸锂，具有层状结构，初始容量可达到133mAh／g，并具有良好的循环性；同时讨论了合成条件对产物结构与性能的影响。     

模板法制备层状锰酸锂正极材料及其电化学性能研究

以商业级大孔径硅胶为模板,利用硅胶的多孔结构制备了具有纳米尺寸的层状锰酸锂正极材料(o-LiMnO_2),采用XRD、SEM和N_2吸附技术对样品进行表征,结果表明模板法制备的LiMnO_2结晶度较好,纯度较高,颗粒尺寸大约30 nm左右.用循环充放电测试考察了产物的电化学性能,结果显示了模板法制备的层状锰酸锂具有较好的电化学循环性能,30次充放电后仍能保持较高容量,而未采用模扳法制备的微米级材料容量衰减严重.     

聚硫硫代聚脲的结构与性能

以液态聚硫橡胶、异氟尔酮二异氰酸酯和扩链剂3，6-二甲硫基-2，5-二甲苯胺为原料，合成了不同硬段质量分数的聚硫硫代聚脲。IR，DMTA，DSC和应力-应变分析表明，各试样的软硬段中存在着相分离；硬段质量分数减少或是液态聚硫橡胶相对分子质量增加时，试样拉伸强度降低而扯断伸长率增加。     

含硫香料——硫代香茅醇、硫代芳樟醇的合成研究

对香茅醇转化为硫代香茅醇及芳樟醇转化为硫代芳樟醇的合成方法及影响因素进行了研究。产品在极低浓度时,硫代香茅醇具有酸杨梅、番石榴的香韵,硫代芳樟醇具有橙桔香韵。     

含硫香料——硫代香茅醇,硫代芳樟醇的合成研究

对香茅醇转化为硫代香茅醇及芳樟醇转化为硫代芳樟醇的合成方法及影响因素进行了研究。产品在极低浓度时,硫代香茅醇具有酸杨梅、番石榴的香韵,硫代芳樟醇具有橙桔香韵。     

硫代二丙酸的合成

本文讨论了由硫代二丙腈水解制硫代二丙酸的方法，并对酸性水解工艺进行了优化。     

聚硫代醚合成的研究进展

介绍了聚硫代醚的合成方法(如缩聚法、加聚法等),特别综述了加聚法的制备原理和应用实例。研究表明:缩聚法合成的聚硫代醚较早实现了工业化且原料价廉,但存在副产物多、产率低及产物后处理复杂等缺点;加聚法合成的聚硫代醚工艺简单、合成条件温和且产率高,原料稍贵但仍可接受,故加聚法合成的聚硫代醚之综合性能优于缩聚法合成的聚硫代醚。最后对聚硫代醚的发展方向进行了展望。     

L－硫代脯氨酸的合成

以Ｌ－半胱氨酸盐酸盐与甲醛为原料，合成Ｌ－硫代脯氨酸，在反应液中加入适量无机盐代替文献方法中的吡啶，同时起到盐析和调节ｐＨ的作用，产物容易析晶，并大大缩短了反应时间，降低了成本，减少了污染，提高了收率．     

硫代二丙腈的合成

本文讨论了硫代二丙腈的合成方法,并通过实验筛选出了最佳反应条件。     

硫代乙酸的合成

以醋酐和Ｈ２Ｓ为原料合成了医药中间体硫代乙酸。     

Structural Analysis of a New Layered Compound: La0.05Sr0.95MnO3

We have found a new phase of La_0.05Sr_0.95MnO₃ with a 30-layer rhombohedral structure by using electron microscopy. The lattice constants were hexagonal axes of a = 0.5444 nm and c = 6.7582 nm. Both weak and strong intensities appeared in selected area diffraction (SAD) patterns. The strong intensities were caused by the periodicity of 15 (Sr,La)O₃ layers that had a new stacking sequence of (cchch)₃. However, the weak intensities indicated that the 15-layer structure has modulation along the c -direction that is twice as long as that of the structure indicated by the strong intensities. We concluded that the modulation of the 30-layer structure was produced by the introduction of two kinds of oxygen octahedra, Mn³⁺O₆ and Mn⁴⁺O₆.     

Silicon and its effect on the electrochemical properties of Li3V2(PO4)3 cathode material

In this study, silicon and its effect on the properties of Li₃V₂(PO₄)₃ were studied for lithium-ion battery applications. The composite material was synthesized and found to show enhanced capacity and cyclability. The presence of silicon in the composites was confirmed. Furthermore, large particles with rough, corroded-like structures formed, and these were distributed well with the silicon particles. The Li₃V₂(PO₄)₃-Si battery had good properties showing improved cyclability, an improved high performance rate, smaller impedance values and improved lithium-ion diffusion coefficients, as determined by cyclic voltammetry. Furthermore, the optimization of the silicon content led to a Li₃V₂(PO₄)₃-Si battery with a 2?wt% silicon loading that had a discharge capacity of 181?mA?h?g^?1. At 2?C, Li₃V₂(PO₄)₃-Si (2?wt%) still demonstrated a capacity of 111.8?mA?h?g^?1, which was 83.8% of its original capacity (compared with 70.3?mA?h?g^?1 and 63.8% for Li₃V₂(PO₄)₃) after 400 cycles.     

Study of structure and conductivity of Li3/8Sr7/16-3x/2LaxZr1/4Nb3/4O3 solid electrolytes

Li_3/8Sr_7/16-3x/2La_xZr_1/4Nb_3/4O₃ (x = 0, 0.05, 0.10, 0.15, 0.20) were synthesized using the conventional solid-state reaction method. In order to increase the vacancy concentration, La³⁺ was doped on the Sr²⁺ site. Crystal structures of doped samples were characterized by X-ray diffraction. Except, perovskite-type Li_3/8Sr_7/16-3x/2La_xZr_1/4Nb_3/4O₃ (x = 0, 0.05, 0.10, 0.15) samples were fabricated by heat treatment at 1250 °C, 1275 °C, 1275 °C and 1275 °C, respectively, for 15 h. Lattice sizes decreased with the increase of doping amounts because of the smaller ion radius of La³⁺ compared to that of Sr²⁺. Ionic conductivities of the samples were measured by AC impedance spectroscopy. The results showed that the ionic conductivity increases at first and then decreases with raising doping amounts and sintering temperatures. So the optimized composition Li_3/8Sr_7/16-3x/2La_xZr_1/4Nb_3/4O₃ (x = 0.05) sintered at 1275 °C was selected with the highest total conductivity of 3.33 × 10^?5 S cm^?1at 30 °C and an activation energy of 0.27 eV. Additionally, potentiostatic polarization test was used to evaluate the electronic conductivity. The optimal composition Li_3/8Sr_7/16-3x/2La_xZr_1/4Nb_3/4O₃ (x = 0.05) as a possible Li-ion conducting solid electrolyte has an electronic conductivity of only 8.39 × 10^?9 S cm^?1.     

Synthesis and characterization of carbon-coated Li3V2(PO4)3 cathode materials with different carbon sources

The carbon-coated monoclinic Li₃V₂(PO₄)₃ (LVP) cathode materials were synthesized by a solid-state reaction process under the same conditions using citric acid, glucose, PVDF and starch, respectively, as both reduction agents and carbon coating sources. The carbon coating can enhance the conductivity of the composite materials and hinder the growth of Li₃V₂(PO₄)₃ particles. Their structures and physicochemical properties were investigated using X-ray diffraction (XRD), thermogravimetric (TG), scanning electron microscopy (SEM) and electrochemical methods. In the voltage region of 3.0-4.3 V, the electrochemical cycling of these LVP/C electrodes all presents good rate capability and excellent cycle stability. It is found that the citric acid-derived LVP owns the largest reversible capacity of 118 mAh g⁻¹ with no capacity fading during 100 cycles at the rate of 0.2C, and the PVDF-derived LVP possesses a capacity of 95 mAh g⁻¹ even at the rate of 5C. While in the voltage region of 3.0-4.8 V, all samples exhibit a slightly poorer cycle performance with the capacity retention of about 86% after 50 cycles at the rate of 0.2C. The reasons for electrochemical performance of the carbon coated Li₃V₂(PO₄)₃ composites are also discussed. The solid-state reaction is feasible for the preparation of the carbon coated Li₃V₂(PO₄)₃ composites which can offer favorable properties for commercial applications.     

Al2O3-ZrO2负载Ni2P催化剂加氢脱硫脱氮活性

采用浸渍-沉淀法制备Al2O3-ZrO2复合氧化物,通过程序升温还原法制备Ni2P/Al2O3-ZrO2催化剂。运用X射线衍射、N2吸附-脱附、X射线光电子能谱技术对载体和催化剂进行表征,并以噻吩加氢脱硫、吡啶加氢脱氮反应为探针考察复合氧化物对Ni2P催化剂加氢活性的影响。结果表明,在Al2O3表面引入少量ZrO2,既保持了γ-Al2O3大比表面积的结构优势,又减少了P或Ni与Al2O3表面的接触,促进Ni2P的形成。载体中ZrO2质量分数20%的Ni2P/Al2O3-ZrO2催化剂活性最高,载体焙烧温度过高会导致催化剂活性下降。     

Photoluminescence behavior on Sr2+ modified CaCu3Ti4O12 based ceramics

Sr²⁺ modified CaSr_xCu_3-xTi₄O₁₂ceramic powders with x?=?ranging from 0.00 to 3.00 were prepared by solid-state reaction. The effects of Sr²⁺ CCTO powders were evaluated by X-ray diffraction (XRD) with Rietveld refinement revealing a mixture of multiple phases. The Raman spectroscopy analysis pointed out that Sr²⁺ addition produces an emission in the blue region, associated to TiO₆ clusters. Optical properties by means of PL analysis showed emission near to blue region for the samples with x?=?0.00, x?=?0.15, x?=?0.30, corresponding to oxygen vacancies. The emission in the violet region is associated to deep defects while emission in the other samples is linked to shallow defects typical of disordered crystalline structures. Less prominent emission in the green region with the increase of Sr²⁺ corresponds to less self-trapped charges, less interaction between electron and hole, and donor–acceptor recombination.     

Synthesis of LiNi0.9Co0.1O2 from Li2CO3, NiO or NiCO3, and CoCO3 or Co3O4 and their electrochemical properties

Cathode active materials with a composition of LiNi_0.9Co_0.1O₂ were synthesized by a solid-state reaction method at 850 °C using Li₂CO₃, NiO or NiCO₃, and CoCO₃ or Co₃O₄, as the sources of Li, Ni, and Co, respectively. Electrochemical properties, structure, and microstructure of the synthesized LiNi_0.9Co_0.1O₂ samples were analyzed. The curves of voltage vs. x in Li_xNi_0.9Co_0.1O₂ for the first charge–discharge and the intercalated and deintercalated Li quantity Δx were studied. The destruction of unstable 3b sites and phase transitions were discussed from the first and second charge–discharge curves of voltage vs. x in Li_xNi_0.9Co_0.1O₂. The LiNi_0.9Co_0.1O₂ sample synthesized from Li₂CO₃, NiO, and Co₃O₄ had the largest first discharge capacity (151 mA h/g), with a discharge capacity deterioration rate of −0.8 mA h/g/cycle (that is, a discharge capacity increasing 0.8 mA h/g per cycle).     

Low temperature synthesis of a new yellowish brown ceramic pigment based on FeNbO4@ZrSiO4

FeNbO₄@ZrSiO₄ ceramic pigments have been successfully synthesized with MgO as mineralizer by an environment-friendly solid-state reaction method at low temperature. The formation of ZrSiO₄ has been investigated by X-ray diffraction, thermogravimetry and differential scanning calorimeter analysis, respectively. The reflectance spectrum and color properties of the FeNbO₄@ZrSiO₄ pigments have been measured and analyzed. Results illustrate that MgO together with Fe₂O₃–Nb₂O₅ can promote the formation of ZrSiO₄ and decrease the synthesis temperature to 1050?°C that is 400–500?°C lower than the characteristic temperature of ZrSiO₄ formation. A series of FeNbO₄@ZrSiO₄ pigments with high thermostability present color changing from bud yellow to earthy yellow as a function of Fe₂O₃–Nb₂O₅ content. The preparation method used in this work possesses many advantages of safety, simplicity of processing and is free of gas phases, indicating a more favorable method to synthesize ZrSiO₄-based pigments. The new yellowish brown FeNbO₄@ZrSiO₄ pigments are promising for high-temperature ceramic pigments applications.     

Physico-chemical characteristics and CO oxidation studies over Pd/(Mn2O3 + SnO2) catalyst

The mixed oxide catalyst (Mn₂O₃ + SnO₂) prepared by the coprecipitation method has been impregnated with Pd metal and it's catalytic behaviour for CO oxidation reaction has been investigated. In the coprecipitated material, Mn₂O₃ and SnO₂ were found to crystallise at 875 K and 1175 K, respectively, which are significantly higher than the crystallisation temperatures of individual oxides prepared under similar conditions. Results of catalytic oxidation of CO, carried out using the pulse method for the mixed oxide system and the individual oxides, suggest significant synergistic effects between these two oxides. The impregnation of palladium metal facilitated CO oxidation and the catalyst Pd/(Mn₂O₃ + SnO₂) was found to be quite effective for CO oxidation even at room temperature. Further, the CO disproportionation has been observed on palladium sites in the temperature range 350 to 400 K for the individual oxide systems.     

Effect of reduction agent on the performance of Li3V2(PO4)3/C positive material by one-step solid-state reaction

The effects of reduction agent on the electrochemical properties of Li₃V₂(PO₄)₃/C positive materials were studied. An one-step solid-state reaction route was applied to synthesize Li₃V₂(PO₄)₃/C samples. The humic acid, glucose and carbon were used as reduction agent. SEM images show that the particles of sample with humic acid as reduction agent merge with each other and form a porous structure, and yet the particles of sample synthesized using carbon as reduction agent are wrapped with small carbon particles and separate each other. Electrochemical tests show that the samples using humic acid and glucose as reduction agents have better cyclic performance than the one using carbon as reduction agent. At the 200th cycle, the sample using humic acid as reduction agent still keeps 145.2 mAh g⁻¹ at 1 C charge and discharge rates. However, the sample using carbon as reduction agent shows a fast decline in capacity during cycling and has 54.5% capacity loss of the initial value after 200 cycles. The results indicate that different reduction agents can obviously affect the morphologies and electrochemical properties of the products.