锂离子蓄电池技术进展及市场前景

锂离子蓄电池是以锂离子在碳负极和嵌入化合物正极中的嵌入和脱嵌为原理发展起来的一种新型蓄电池.到目前为止,国外1865型圆柱Li_xC/LIPF_6—EC+DEC/Li_1-xCoO_2锂离子蓄电池的比能量已达到105Wh/kg和270Wh/L.而其月自放电已降至12%以下,在100%DOD和lC率下的循环寿命达到1000次.这种电池已广泛应用于大哥大,摄相机及笔记本计算机等设备中,还有可能在将来应用于电动汽车中作电源.     

蒙脱石有机插层复合物的制备及XRD分析

以辽宁某地钙基蒙脱石为原料,经碳酸钠钠化改型后,用十六烷基三甲基溴化铵作插层剂对其进行有机插层处理,考察插层剂的最佳用量。采用XRD技术对所研制的蒙脱石有机插层复合物进行分析,结果表明,插层剂用量为120%mmol/100gCEC时所制备的蒙脱石有机插层复合物的插层效果最好。     

Superconducting Properties of Iodine-Intercalated Bi<Subscript>2</Subscript>Sr<Subscript>2</Subscript>Ca<Subscript>2</Subscript>Cu<Subscript>3</Subscript>O<Subscript>10+<Emphasis Type="Italic">x</Emphasis></Subscript>

The superconducting properties of iodine-intercalated high-temperature superconducting Bi₂Sr₂Ca₂Cu₃O_10+x phase (Bi-2223) were systematically studied. It was found that for samples containing a significant amount of Bi₂Sr₂CaCu₂O_8+x , iodine intercalation results in the dramatic decrease of the inter-granular critical current density, as well as a significant decrease of the critical temperature (T _c), the critical current density in the grains (J _cg), and of the amount of Bi-2223. For samples with a large amount of Bi-2223, T _c changes insignificantly, whereas J _cg can even increase. We argue that the different behavior of the superconducting parameters is the result of various oxygen concentrations, and we explain the effect of iodine intercalation based on the parabolic dependence between T _c and the number of holes per CuO₂ layer. The H(T) curves (determined from the peak position in the loss signal of ac susceptibility) for intercalated samples deviate significantly from the quasi 2D-like behavior, pointing toward an enhancement of the 3D fluctuations of vortices. For the change in the values and dimensionality of the flux pinning in the process of the intercalation, we attempted a qualitative explanation based on the models proposed in literature.     

Formation of Nd2Fe14B hydride by milling of anhydride particles in toluene in a closed reactor

When milling micrometer thin Nd₂Fe₁₄B platelets, of an average 1–2 mm diameter, in toluene in a closed reactor, part of the toluene decomposes at the surface of the platelets and yields nascent hydrogen and carbon/low hydrocarbons. The hydrogen diffuses into the Nd₂Fe₁₄B platelets and the carbon forms a thin surface passivation layer of the platelets, forming the stable Nd₂Fe₁₄BH _x ,x ≤ 5, hydride at room temperature. On heating in a calorimeter, the hydrogen desorbs off the sample with a well-defined endotherm between 370 and 425 K. An N₂ gas atmosphere, if used during the heating, facilitates the H-desorption process with the modified kinetic parameters. For example, the enthalpy of the H-desorption ΔH and the related activation energyE _a have the measured values ΔH = 153 J/g andE _a = 58·2 kJ/mol in argon and ΔH = 256 J/g andE _a = 41·6 kJ/mol in N₂. It is argued that N₂ gas has a fast reaction with the H atoms desorbing off the thin sample platelets and forms NH₃ gas with an instantaneous decrease of the total external gas pressure at the sample. This supports the fast desorption of H atoms in the sample with the modified desorption kinetics in N₂ gas.     

Mesoporous assembly of 2D manganate nanosheets intercalated with cobalt ions

Mesoporous compound of cobalt-layered manganese oxide was synthesized by self-assembly reaction between 2D manganate nanosheets and cobalt ions. It was found that 2D manganate nanosheets are interstratified with cobalt ions, leading to the formation of porous intercalation heterostructure with expanded surface area of ∼ 44-100 m²/g. The mesopores with the average diameters of ∼ 11-17 nm originate from the house-of-cards type stacking of the layered manganate crystallites. Co K- and Mn K-edge X-ray absorption spectroscopy revealed that both the cobalt and manganese ions are stabilized in octahedral symmetry with the mixed oxidation states of Mn³⁺/Mn⁴⁺ and Co²⁺/Co³⁺. Considering high oxidation states of component metal ions, this porous material is expected to be very useful as redox catalysts and/or lithium intercalation electrodes.     

含泥化夹层顺层和反倾岩质边坡动力响应差异性研究

设计并制作了两个同尺寸的含泥化夹层顺层和反倾岩质边坡,并进行了大型振动台试验,对含泥化夹层顺层和反倾岩质边坡的动力响应差异性进行了分析,研究结果表明:顺层边坡坡体内部加速度放大系数整体上小于反倾边坡;在坡体中上部(相对高度大于0.4),顺层边坡坡面加速度放大系数大于反倾边坡,在坡体下部(相对高度小于等于0.4),顺层边坡坡面加速度放大系数与反倾边坡近似相等;顺层边坡和反倾边坡坡面位移随输入地震动强度增大而大幅度增加,顺层边坡坡面位移大于反倾边坡,且随着输入地震波幅值的增加,顺层边坡和反倾边坡坡顶位移之间的差值增大;反倾边坡较顺层边坡具有更高的地震稳定性;顺层边坡破坏形式主要表现为坡体后缘的垂直张拉裂隙、岩层沿泥化夹层的顺层滑动以及坡顶岩块崩落,而反倾边坡的破坏形式主要表现为坡面水平向和垂直向裂隙交错、泥化夹层挤出以及坡顶被震碎。     

乙烯-丙烯酸酯-马来酸酐三元共聚物熔融插层有机蒙脱土对膨胀阻燃聚丙烯薄膜性能的影响

以新型成炭剂(CFA)、改性聚磷酸铵(MAPP)、乙烯-丙烯酸酯-马来酸酐三元共聚物熔融插层有机蒙脱土(EMH-OMMT)母粒复配成膨胀阻燃剂(IFR),与聚丙烯(PP)共混后通过流延薄膜机制备膨胀阻燃PP薄膜。对其进行了阻燃性能、力学性能测试,并运用热重分析表征了其热分解过程。相比未熔融插层OMMT和传统的4A分子筛协效剂,EMH-OMMT不仅提高了体系的阻燃性能,使薄膜(0.2mm)在IFR添加28%时通过了VTM-0级,而且明显提高了体系的力学性能。     

聚酰亚胺/有机蒙脱土/丁苯橡胶复合材料性能的研究

将聚酰亚胺(PI)与有机蒙脱土(OMMT)混合,制备了PI/OMMT粉状材料;将粉状材料与丁苯胶乳(SBR)混合,制备了颗粒状PI/OMMT/SBR复合材料.SEM照片显示,有机蒙脱土可改善聚酰亚胺与丁苯橡胶的相容性.X射线衍射(XRD)结果表明,聚酰亚胺分子链与丁苯橡胶分子链一起插入有机蒙脱土层间,使层间距变大;有机蒙脱土作为交联点存在.动态力学性能测试结果表明,在频率扫描下,加入PI/OMMT后丁苯橡胶的G′最高,但tanδ较低.     

坝体材料非线性对坝基深层抗滑稳定影响分析

结合亭子口水利枢纽升船机上闸首坝基深层抗滑稳定研究,采用非线性有限元法对坝基软弱夹层及抗滑齿槽受荷破坏过程进行了计算分析。为考证齿槽周边坝体混凝土是否会先于软弱夹层屈服,考虑坝体材料为非线性本构关系,并将计算成果与坝体材料为线性本构关系的结果进行比较,分析认为坝体为非线性材料时计算出来的安全系数较小。计算表明,升船机上闸首在设置抗滑齿槽后,整个坝基系统的安全系数较高,坝基深层抗滑稳定是安全的。