Zn:Fe:LiNbO3单晶的坩埚下降法生长及其成分研究

通过优选合适的化学原料，用坩埚下降法生长出了无宏观缺陷的Zn：Fe：LiNbO3(Zn：Fe：LN)单晶。生长的工艺参数是：用微凸生长界面生长，生长速度为1～3mm／h，温度梯度为20～30℃／cm。用X射线衍射及DTA对晶体进行了分析；测定了晶体的吸收光谱。结果表明：所有Zn：Fe：LN晶体中的Fe^2 浓度沿生长方向增加；掺杂3％ZnO(摩尔分数)的Zn：Fe：LN单晶中的Fe^2 浓度沿生长方向的变化量比掺杂6％ZnO的大。从坩埚下降法的温场特点、晶体的热处理过程、环境气氛，以及ZnO组分对Fe离子的排斥作用解释了产生Fe^2 离子浓度变化的原因。     

聚丙烯酸锂的合成与性能

研制了一种新型阳离子导电聚合物—聚丙烯酸锂 (PAALi) ,分子量在 2 0 ,0 0 0～4 0 0 ,0 0 0范围内 ,室温离子电导率为 10 - 8～ 10 - 9S·cm- 1;研究了聚合条件对产率的影响 ;探讨了分子量、锂离子含量、温度对其离子导电率的影响。     

In:Fe:LiNbO_3晶体波导基片光折变性能的研究

采用Czochralski技术生长了掺In摩尔分数分别为1%,2%和3%的In∶Fe∶LiNbO3晶体。测试In∶Fe∶LiNbO3晶体的红外光谱发现:3%In∶Fe∶LiNbO3晶体的OH-吸收峰由Fe∶LiNbO3晶体的3484cm-1位移到3507cm-1。首次以全息法研究了In∶Fe∶LiNbO3晶体波导基片光折变灵敏度。研究表明:晶体波导基片的光折变灵敏度大小顺序为Fe∶LiNbO3>1%In∶Fe∶LiNbO3>2%In∶Fe∶LiNbO3>3%In∶Fe∶LiNbO3。采用锂空位模型讨论了3%In∶Fe∶LiNbO3晶体OH-吸收峰位移的机理。讨论了In∶Fe∶LiNbO3晶体波导基片光折变灵敏度减弱和抗光折变能力增强的机理。     

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.     

一种新型的锂离子二次电池的电解质

本文介绍了氟烷基膦酸锂盐的一种Li[PF3(C2F5)3]的制备做了介绍，并将Li[PF3(C2F5)3]的电解液和六氟磷酸锂(LiPF6)的电解液在对水的稳定性，电化学稳定性，离子导电性以及热稳定性方面做了比较。     

Synthesis and electrochemical characterization of a new Se-doped spinel material for lithium secondary batteries

A new Se-doped spinel material, LiAl_0.18Se_0.02Mn_1.8O₄ powder with a phase-pure polycrystalline was synthesized by a sol–gel method. The material in the 3 V region (2.4 3.5 V) and both the 3 and 4 V region (2.4 4.4 V) initially deliver a discharge capacity of 81 and 178 mA h g^–1 which increase with cycling to reach 110 and 204 after 50 cycles, respectively. The material shows excellent cycleability in the 4 V region (3.0 4.4 V) with almost no capacity loss. The structural integrity of the Se-doped spinel was characterized by charge–discharge cycling tests and X-;ray diffraction.     

Cycling of lithium/metal oxide cells using composite electrolytes containing fumed silicas

The effect on cycle capacity is reported of cathode material (metal oxide, carbon, and current collector) in lithium/metal oxide cells cycled with fumed silica-based composite electrolytes. Three types of electrolytes are compared: filler-free electrolyte consisting of methyl-terminated poly(ethylene glycol) oligomer (PEGdm, M_w=250)+lithium bis(trifluromethylsufonyl)imide (LiTFSI) (Li:O=1:20), and two composite systems of the above baseline liquid electrolyte containing 10-wt% A200 (hydrophilic fumed silica) or R805 (hydrophobic fumed silica with octyl surface group). The composite electrolytes are solid-like gels. Three cathode active materials (LiCoO₂, V₆O₁₃, and Li_xMnO₂), four conducting carbons (graphite Timrex® SFG 15, SFG 44, carbon black Vulcan XC72R, and Ketjenblack EC-600JD), and three current collector materials (Al, Ni, and carbon fiber) were studied. Cells with composite electrolytes show higher capacity, reduced capacity fade, and less cell polarization than those with filler-free electrolyte. Among the three active materials studied, V₆O₁₃ cathodes deliver the highest capacity and Li_xMnO₂ cathodes render the best capacity retention. Discharge capacity of Li/LiCoO₂ cells is affected greatly by cathode carbon type, and the capacity decreases in the order of Ketjenblack>SFG 15>SFG 44>Vulcan. Current collector material also plays a significant role in cell cycling performance. Lithium/vanadium oxide (V₆O₁₃) cells deliver increased capacity using Ni foil and carbon fiber current collectors in comparison to an Al foil current collector.     

大量Li+存在的卤水体系中容量法测定Ca2+的分析方法研究

在Li 、Ca2 共存的相化学研究中,大量Li 的存在对配位滴定法测定Ca2 易产生较大干扰,致使卤水体系中钙的测定结果产生较大偏离。本文在进一步研究了用三乙醇胺作掩蔽剂消除Li 干扰的实验基础上,对高锂钙比(mLi∶mCa≥5)消除Li 的干扰,首次发现正丁醇-无水乙醇的混合液可有效掩蔽共存Li 的干扰。实验结果表明,该方法可使Ca2 分析结果相对误差不超过0.3%。样品加标回收率为99.90%~100.09%,相对标准偏差<0.2%。     

Binder effect on cycling performance of silicon/carbon composite anodes for lithium ion batteries

The cycling performance of a silicon/carbon composite anode has been significantly enhanced by using acrylic adhesive and modified acrylic adhesive as binder to fabricate the electrodes for lithium ion batteries. The capacity retentions of Si/C composite electrodes bound by acrylic adhesive and modified acrylic adhesive are 79% and 90% after 50 cycles, respectively. These two binders are electrochemically stable in the organic electrolyte in the working window. They also show larger adhesion strength between the coating and the Cu current collector as well as smaller solvent absorption in the electrolyte solvent than polyvinylidene fluoride (PVDF). Furthermore, sodium carboxyl methyl cellulose (CMC) plays an important role on improving the properties of acrylic adhesive, which increases the adhesive strength of acrylic adhesive and improves the activation of the electrodes.     

Advanced Sn/C composite anodes for lithium ion batteries

Metallic tin was deposited in fine particulate form on the surface of carbonaceous mesophase spherules (CMS) and in the pores of porous carbon by the decomposition and reduction of tin(II) 2-ethylhexanoate at 450 °C. The Sn/C composite powders obtained were used as anode materials for lithium ion cells. Electrochemical cycling tests of coin cells show that the dispersion of tin into the carbonaceous materials enhances the reversible capacity of the electrodes. The capacity retention at the 50th cycle is 91 % for Sn/CMS composite containing 22% tin, against 428 mAh g^–1 at the first cycle. With further increase in tin content, the capacity fade upon cycling is more rapid.