Co^3＋—modified Surface of LiMn2O4 Spinel for its Improvementof Electrochemical Properties

Cobalt was used to modify the surface of spinel LiMn2O4 by a solution technique to produce Co^3 -modified surface material (COMSM). Cobalt was only doped into the surface of LiMn2O4 spinel. XPS(X-ray photoelectron spectroscopy) analysis confirms the valence state of Co^3 . COMSM has stable spinel structure and can prevent active materials from the corrosion of electrolyte. The ICP(inductively coupled plasma) determination of the spinel dissolution in electrolyte showed the content of Mn dissolved from COMSM was smaller than that from the pure spinel. AC impedance patterns show that the charge-transfer resistance (Rct) for COMSM is smaller than that for pure spinel. The particles of COMSM are bigger in size than those of pure spinel according to the micrographs of SEM(scanning electron microscopy). The determinations of the electrochemical characterization show that COMSM has both good cycling performance and high initial capacity of 124.1 mA/h at an average capacity loss of 0.19 mAh/g per cycle.     

LiFePO4基正极材料容量的温度敏感特性及交流阻抗谱研究

采用原位碳包覆法制备了锂离子二次电池用LiFePO4／C复合正极材料。考察了环境温度对LiFePO4/C电池容量的影响，得到容量与绝对温度之间符合Arrhenius关系。运用交流阻抗谱分析了温度与电池电化学特性的关系，并对电极基于电荷和质量传递控制过程给出了一种新的模拟等效电路，通过Zview拟合软件得到了各个模拟元件的数值及变化趋势，从而定量地解释LiFePO4／C复合电极容量与温度的关系。     

磁化水配料对TiO2压敏陶瓷电性能和微观结构的影响

研究了使用磁化水配料对TiO2压敏陶瓷电性能和微观结构的影响。电性能测量及SEM和XRD微观结构分析结果表明：磁化水配料制备的TiO2压敏电阻具有较低的压敏电压和较高的非线性指数α。材料的主晶相为金红石相，由Ce,Si,Ti组成的Perrierite第二相均匀分布在晶界区域。因此，采用磁化水配料可以改善材料的工艺性能和陶瓷烧结体的微观结构，从而提高元件的电性能。     

锂离子电池固态聚合物电解质研究进展

电解质是制备高功率密度和高能量密度、长循环寿命的锂离子电池的重要材料之一,而聚合物电解质是实现全固态锂离子电池的关键技术.总结近几年来为提高聚合物电解质电导率所作研究的新进展,并提出了今后的研究方向.     

BaTiO3系PTCR材料电学性能的复阻抗解析

采用复阻抗解析法研究了ＢａＴｉＯ３系ＰＴＣＲ材料晶粒、晶界的电学性能。结果表明：使用欧姆接触电极的ＰＴＣＲ材料等效电路的复阻抗为：晶粒电阻呈ＮＴＣ特性，而晶界电阻天Ｔ〈Ｔｃ时呈ＮＴＣ特性，Ｔ〉Ｔｃ时呈明显的ＰＴＣ特性；ＰＴＣ效应是一种晶界效应。     

光纤光栅形状传感器的研究

传感器总长810mm,直径为2.5mm,4根光纤布喇格光栅(fiber Bragg grating,FBG)互成90°分布在用记忆合金丝(Shap Memory Alloy,SMA)做基材的表面。通过在波分复用的基础上添加光时分复用来改进传感网络布置,提高测量精度;同时,设计了一套封装装置来确保封装时FBG与基材之间的准确定位以及黏结剂能够均匀的涂覆在基材和FBG表面,提高传感器的封装精度。实验结果表明,该FBG形状传感器的测量精度为3.1%。     

精密激光刻划机中的光学技术

本文介绍的工作台用计算机结合光电编码器控制伺服电机驱动的精密激光刻划机，运用激光轴予偏置以适应非平面工件刻划，以激光或不同线密度改变刻线宽度，用微光点指示工位等光学技术，有效地提高了整机的高精度高质量刻划性能。     

精甲醇火车槽车的组合清洗

叙述精甲醇火车槽车启用前进行清洗的必要性.采用组合清洗工艺对槽车内壁进行清洗,达到了非常好的效果.     

纳米级二氧化锆粉体合成新方法

以分析纯氢氧化钠和氯氧化锆为原料,通过低温强碱合成法简单,方便地合成了二氧化锆晶核。通过４００℃的热处理形成四方或立方相二氧化锆超细粉,其一次颗粒尺寸约为７ｎｍ左右。     

Effect of Ta2O5 in (Ca,Si, Ta)-doped TiO2 ceramic varistors

TiO₂ varistors doped with 0.2 mol% Ca, 0.4 mol% Si and different concentrations of Ta were obtained by ceramic sintering processing at 1350 °C. The effect of Ta on the microstructures, nonlinear electrical behavior and dielectric properties of the (Ca, Si, Ta)-doped TiO₂ ceramics were investigated. The ceramics have nonlinear coefficients of α = 3.0–5.0 and ultrahigh relative dielectric constants which is up to 10⁴. Experimental evidence shows that small quantities of Ta₂O₅ improve the nonlinear properties of the samples significantly. It was found that an optimal doping composition of 0.8 mol% Ta₂O₅ leads to a low breakdown voltage of 14.7 V/mm, a high nonlinear constant of 4.8 and an ultrahigh electrical permittivity of 5.0 × 10⁴ and tg δ = 0.66 (measured at 1 kHz), which is consistent with the highest and narrowest grain boundary barriers of the ceramics. In view of these electrical characteristics, the TiO₂–0.8 mol% Ta₂O₅ ceramic is a viable candidate for capacitor–varistor functional devices. The characteristics of the ceramics can be explained by the effect and the maximum of the substitution of Ta⁵⁺ for Ti⁴⁺.