Ionic conductivity in crystalline polymer electrolytes

Polymer electrolytes are the subject of intensive study, in part because of their potential use as the electrolyte in all-solid-state rechargeable lithium batteries. These materials are formed by dissolving a salt (for example LiI) in a solid host polymer such as poly(ethylene oxide) (refs 2, 3, 4, 5, 6), and may be prepared as both crystalline and amorphous phases. Conductivity in polymer electrolytes has long been viewed as confined to the amorphous phase above the glass transition temperature, Tg, where polymer chain motion creates a dynamic, disordered environment that plays a critical role in facilitating ion transport. Here we show that, in contrast to this prevailing view, ionic conductivity in the static, ordered environment of the crystalline phase can be greater than that in the equivalent amorphous material above Tg. Moreover, we demonstrate that ion transport in crystalline polymer electrolytes can be dominated by the cations, whereas both ions are generally mobile in the amorphous phase. Restriction of mobility to the lithium cation is advantageous for battery applications. The realization that order can promote ion transport in polymers is interesting in the context of electronically conducting polymers, where crystallinity favours electron transport.     

非简并共轭高聚物中的弛豫过程

研究了非简并共轭高聚物中的两种典型的动力学方程：（１）光激发，（２）电荷转移，并确定它们的弛豫时间。晶格位形和电子能态随时间的演变过程自洽地显示出光激发的弛豫时间大约是８５ｆｓ，电荷转移的弛豫时间大约是１５０ｆｓ，很明显，光激发的弛豫比电荷转移弛豫的过程要快得多，并指出这种现象在高分子材料中是一种普遍现象，同时给出了物理讨论。     

Increasing the conductivity of crystalline polymer electrolytes

Polymer electrolytes consist of salts dissolved in polymers (for example, polyethylene oxide, PEO), and represent a unique class of solid coordination compounds. They have potential applications in a diverse range of all-solid-state devices, such as rechargeable lithium batteries, flexible electrochromic displays and smart windows. For 30 years, attention was focused on amorphous polymer electrolytes in the belief that crystalline polymer:salt complexes were insulators. This view has been overturned recently by demonstrating ionic conductivity in the crystalline complexes PEO6:LiXF6 (X = P, As, Sb); however, the conductivities were relatively low. Here we demonstrate an increase of 1.5 orders of magnitude in the conductivity of these materials by replacing a small proportion of the XF6- anions in the crystal structure with isovalent N(SO2CF3)2- ions. We suggest that the larger and more irregularly shaped anions disrupt the potential around the Li+ ions, thus enhancing the ionic conductivity in a manner somewhat analogous to the AgBr(1-x)I(x) ionic conductors. The demonstration that doping strategies can enhance the conductivity of crystalline polymer electrolytes represents a significant advance towards the technological exploitation of such materials.     

PAN基凝胶聚合物电解质超级电容器的研究

制备了PAN基凝胶聚合物电解质及PAN基凝胶聚合物超级电容器.采用交流阻抗法测量了凝胶聚合物电解质的离子电导率.采用交流阻抗、循环伏安、恒流充放电等测试方法研究了凝胶聚合物电解质超级电容器的性能,并对交流阻抗谱进行了模拟分析.结果表明,PAN基凝胶聚合物电解质的电导率在室温下可达7.54m s.cm-1,以活性炭为电极材料,内聚合的方式制备的PAN基凝胶聚合物电解质电容器的工作电压可达2.5V,内阻为8.92-12.6Ω.cm2,比容量达20.6 F/g(i=0.5 mA/cm2).     

PUA对光固化PEO基高分子固体电解质性能的影响

将聚醚型(A1)和聚酯型(A2)两种特定结构的聚氨酯丙烯酸酯(PUA)分别与聚乙二醇丙烯酸双酯(PEGDA)、LiX、光引发剂等混合制成光敏体系,然后经UV固化得到高分子固体电解质(SPE)薄膜,并对其机械性能和导电性能进行了测定.结果表明:这两种固体电解质膜的机械性能都比纯聚氧乙烯(PEO)为基体的电解质膜好,加入适当比例的A1的电解质膜的导电性能与以PEO为基体的电解质膜相近,但加入A2的电解质膜的导电性能变差.     

电致变色器件用聚合物凝胶电解质研究进展

电解质是电致变色器件的重要组成部分,为变色反应提供所必需的补偿离子,其性能直接影响器件的响应速率、光学对比度和使用寿命.聚合物凝艘电解质易加工封装且具有较高的离子电导率,因而被广泛用于电致变色器件中.综述了电致变色器件用聚合物凝胶电解质的研究进展,着重介绍了新型离子凝胶和聚离子凝胶电解质在电致变色器件中的应用、存在的问题及发展建议.     

电致变色器件用聚合物凝胶电解质研究进展

电解质是电致变色器件的重要组成部分,为变色反应提供所必需的补偿离子,其性能直接影响器件的响应速率、光学对比度和使用寿命.聚合物凝艘电解质易加工封装且具有较高的离子电导率,因而被广泛用于电致变色器件中.综述了电致变色器件用聚合物凝胶电解质的研究进展,着重介绍了新型离子凝胶和聚离子凝胶电解质在电致变色器件中的应用、存在的问题及发展建议.     

凝胶聚合物电解质MnO2/AC电容器的研究

采用液相氧化法制备了MnO2超级电容器电极材料,以MnO2为正极材料,活性炭(AC)为负极材料,丙烯腈作聚合物单体,碳酸二甲酯(DMC)与碳酸乙烯酯(EC)的混和液作增塑剂,高氯酸锂为支持电解质,采用内聚合法制备PAN基凝胶聚合物电解质MnO2/AC混合电容器.通过循环伏安、交流阻抗、恒流充放电等测试方法对混合电容器的电化学性能进行了测试.结果表明:混合电容器的工作电压为2.5 V,比容量为27.3 F/g(i=0.5 mA/cm2),比同电解质体系的AC/AC电容器提高约48.21%.     

Optimization of polymer electrolytes for quasi-solidstate dye-sensitized solar cells

The dye-sensitized nanocrystalline TiO2 thin filmsolar cells (DSSCs) have attracted much attention since1990s[1— , due to their high light to electrical energy 4]conversion efficiency. So far, many studies have beenmade on the use of liquid electrolytes such as acetonitrile,3-methoxypropionitrile and a mixture of ethylene/pro-pylene carbonate (EC/PC) containing I? /I3 redox cou-?ple. A light to electrical energy conversion efficiency of7%— 12% has been obtained for DSSC using liquid e…     

Electrochemical behaviors of novel composite polymer electrolytes for lithium batteries

A novel composite polymer electrolyte was prepared by blending an appropriate amount of LiClO₄ and 10% (mass fraction)fumed SiO₂ with the block copolymer of poly (ethylene oxide) (PEO) synthesized by poly (ethylene glycol) (PEG) 400 and CH₂Cl₂.The ionic conductivity, electrochemical stability, interfacial characteristic and thermal behavior of the composite polymer electrolytewere studied by the measurements of AC impedance spectroscopy, linear sweep voltammetry and differential scanning calorimetry(DSC), respectively. The glass transition temperature acts as a function of salt concentration, which increases with the LiClO₄ content.Lewis acid-base model interaction mechanism was introduced to interpret the interactive relation between the filled fumed SiO₂ andthe lithium salt in the composite polymer electrolyte. Over the salt concentration range and the measured temperature, the maximumionic conductivity of the composite polymer electrolyte (10-4.41 S/cm) appeared at EO/Li=25 (mole ratio) and 30℃, and the begin-ning oxidative degradation potential versus Li beyond 5 V.     

Quasi—solid—state nanocrystalline TiO2 solar cells using gel network polymer electrolytes based on polysiloxanes

A quasi-solid-state dye-sensitized manocrystal-line porous TiO2 film solar cell was fabricated using a novel gel network polymer electrolyte based on polysiloxanes with both polyethylene oxide internal plasticized side chains and quaternary ammonium groups.The cell exhibited better photoelectrical conversion performance under 60 mW/cm^2 irradiation.The short photocurrnt (Isc) of 5.0mA/cm^2 and open voltage(Voc) of 0.68V were achieved,and the energy conversion efficiency(η) and fill factor (ff) were 3.4% and 0.60,respectively.     

PVA基碱性复合聚合物电解质的制备及其性能

以聚乙烯醇(PVA)、丙三醇(GROL)、SiO2、KOH为原料,采用溶液浇铸法制备PVA基碱性复合聚合物电解质(ASPE)膜.运用交流阻抗法、循环伏安法、X线衍射和红外光谱等技术表征其性能.研究结果表明:添加增塑剂GROL后体系的电化学稳定窗口及力学性能有所降低,在具备良好机械强度前提下,适量GROL的加入可以显著提高体系的离子电导率;PVA/SiO2/KOH/H2O ASPE显示了良好的电化学性能和力学性能,当SiO2添加量为7%(质量分数)时,碱性聚合物电解质的室温离子电导率达到最高14.56×10-3 S/cm,与纯PVA/KOH相比提高了1个数量级;电化学稳定窗口为2.4V,50次循环后窗口大小基本不变.     

论图书馆的休闲功能

在充分认识休闲价值的基础上,指出休闲功能应成为图书馆的又一价值选择,在世界即将进入“休闲时代”的今天,开发图书馆的休闲功能对于提高图书馆的人气,对于拓展图书馆的服务,对于图书馆的自身发展都具有十分重要的意义。     

Relationship between Arctic Oscillation and Pacific Decadal Oscillation on decadal timescale

The Pacific Decadal Oscillation (PDO) is one of the main modes to describe the climate variability in the North Pacific (NP)[1-5]. Recent studies showed that PDO is related to winter surface air temperature and precipitation over North America[3,6], the c…     

论短跑的放松跑技术

本文讨论了短跑的放松跑技术,重新对其进行正确认识,并探讨它对提高短跑成绩的作用。     

超声场对毛细管内电解质浸出过程的影响

为探讨超声场强化化工分离过程的机理 ,以充满电解质溶液的短毛细管中溶质的浸出模拟固液分离体系 ,通过测定浸出动力学曲线 ,探讨了超声场对这一浸取过程的强化作用机理 ,分析了微扰效应对传质过程的影响。实验结果表明 ,超声空化的微扰效应强化了溶质在毛细管内部的扩散 ,且强化作用随毛细管径及超声场强的增大而增大。与升温的强化效果相比较 ,超声场的微扰效应和湍动效应兼顾了强化内外扩散的两个方面 ,与升温浸取过程相比 ,超声场的强化手段更具优势     

用于纳秒级脉冲电场测试的加载天线研究

针对宽频带、大动态、高灵敏度的脉冲电场测试技术始终是电磁脉冲测试研究领域的1个难点,在国家自然科学基金资助下,研制成功了V型加载偶极子天线测试系统,并通过传输函数、方向图实验、计量标定和测试实验验证表明:该测试系统具有宽频带、快响应、小失真的特点,能够满足小于1 ns的静电放电辐射场的测试要求。     

多晶体热弹性弛豫中的红外发散响应

本文应用红外发散模型计论多晶体内的热弹性弛豫过程。在用热力学理论和热传导定律处理固体热弹性弛豫的基础上,考虑了由界面内无序的多休相互作用导致的红外发散响应,修正了熵产生的速率方程,导得热弹性内耗峰公式。此公式得到实验的证实,由此解释多晶体内热流引起的内耗峰的增宽和不对称性。     

核磁共振弛豫和辐射阻尼效应的计算机模拟

对核磁共振弛豫过程和辐射阻尼效应进行了理论分析和计算机模拟,以直观明了的方式描述了这些物理过程,并对模拟结果进行了讨论.模拟结果表明:横向弛豫和纵向弛豫过程在辐射阻尼很小时,不管实验参数如何设定,磁化矢量路径始终发生在以平衡态磁化矢量为半径的球内;当受到强辐射阻尼影响时,磁化矢量路径则发生在以平衡态磁化矢量为半径的球面上.     

聚合物驱后地层残留聚合物再利用技术研究

聚合物驱转水驱后含水率上升快,同时地下又残留大量聚合物,以溶液溶解、吸附、捕集的形式存在.为了解决这个问题,提出了向地层注入再利用剂将地层残留聚合物再利用,形成弱冻胶或(和)絮凝体,封堵高渗透层,控制水的窜流,通过提高波及系数提高原油采收率.残留聚合物再利用技术包括固定技术和絮凝技术.研究证实,絮凝技术主要利用地下低质量浓度的聚合物,固定技术主要利用地下高质量浓度的聚合物.絮凝剂可用固体颗粒,优化的絮凝剂为稳定化钠土;固定剂可用聚合物交联剂,优化的固定剂由地层温度和矿化度决定,对孤岛油田地层条件优选为醋酸铬与乳酸铬的混合物(YG107).该技术在双河油田和孤岛油田矿场试验取得了很好效果,是聚合物驱后提高采收率首要的接替技术.