Nanocomposite polymer electrolytes containing silica nanoparticles: Comparison between poly(ethylene glycol) and poly(ethylene oxide) dimethyl ether

Nanocomposite polymer electrolytes consisting of low molecular weight poly(ethylene oxide) (PEO), iodine salt MI (M = K⁺, imidazolium⁺), and fumed silica nanoparticles have been prepared and characterized. The effect of terminal group in PEO, i.e., hydroxyl (? OH) and methyl (CH₃) using poly(ethylene glycol) (PEG) and PEO dimethyl ether (PEODME), respectively, was investigated on the interactions, structures, and ionic conductivities of polymer electrolytes. Wide angle X‐ray scattering (WAXS), differential scanning calorimetry (DSC), and complex viscositymeasurements clearly showed that the gelation of PEG electrolytes occurred more effectively than that of PEODME electrolytes. It was attributed to the fact that the hydroxyl groups of PEG participated in the hydrogen‐bonding interaction between silica nanoparticles, and consequently helped to accelerate the gelation reaction, as confirmed by FTIR spectroscopy. Because of its interaction, the ionic conductivities of PEG electrolytes (maximum value ～ 6.9 × 10^?4 S/cm) were lower than that of PEODME electrolytes (2.3 × 10^?3 S/cm). © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Electrical conductivity of Al-doped Li2ZrO3 ceramics for Li-ion conductor electrolytes

All-solid-state Li-ion batteries (LIBs) have recently attracted widespread attention for their high energy density and safety. Some research have conducted on the Li₂ZrO₃-based Li-ion conductor electrolytes, while there is little work on the conductivity below 100 °C, although it is very important for LIBs work around room temperature. Here, monoclinic Li₂ZrO₃-based ceramics are prepared via a wet chemistry method, and the conductivities of Li₂ZrO₃ ceramics are tuned by defect engineering of Al³⁺ ions introduction. The conductivity of Al-doped Li₂ZrO₃ reaches up to 3.06 × 10^-4 S cm^-1 at 25 °C, the related activation energy of conduction is less than 0.1 eV. Simulation calculation using bond valence site energy reveals that there is a two-dimensional Li-ion migration network in the crystal structure of Li₂ZrO₃.     

The conductivity behaviour of gamma-irradiated PEO-LiX electrolytes. I

In an attempt to enhance the room temperature ionic conductivity of PEO-LiX films, samples have been exposed to gamma-irradiation at 78°C. The success with which cross-links have been introduced into the amorphous form has been evaluated from d.s.c. analysis and temperature-dependent conductivity data. Retardation of the recrystallisation event, associated with uncomplexed poly(ethylene oxide), does not occur over a range of total doses. Changes in overall conductivity levels for the PEO-LiCF₃SO₃ ([EO units]/[Li] = 9) system, indicate light cross-linking at 2.25 Mrad of exposure. However, higher doses result in a substantial amount of chain scission, leading eventually to poor mechanical properties. A similar study on PEO-LiClO₄ ([EO units]/[Li] = 20) confirms that the above route is an ineffective method to improve room temperature conductivity.     

Improving ionic conductivity of polymer-based solid electrolytes for lithium metal batteries

Because of its superior safety and excellent processability, solid polymer electrolytes (SPEs) have attracted widespread attention. In lithium based batteries, SPEs have great prospects in replacing leaky and flammable liquid electrolytes. However, the low ionic conductivity of SPEs cannot meet the requirements of high energy density systems, which is also an important obstacle to its practical application. In this respect, escalating charge carriers (i.e. Li⁺) and Li⁺ transport paths are two major aspects of improving the ionic conductivity of SPEs. This article reviews recent advances from the two perspectives, and the underlying mechanism of these proposed strategies is discussed, including increasing the Li⁺ number and optimizing the Li⁺ transport paths through increasing the types and shortening the distance of Li⁺ transport path. It is hoped that this article can enlighten profound thinking and open up new ways to improve the ionic conductivity of SPEs.     

Enhancement of thermal conductivity of ethylene glycol based silver nanofluids

Nanofluid is a kind of new engineering material consisting of solid particles with size typically of 1-100 nm suspended in base fluids. Nanofluids offer excellent scope of enhancing thermal conductivity of common heat transfer fluids. In the present study, nanofluids are synthesized using silver nitrate (precursor), ethylene glycol (reducing agent), and poly(acrylamide-co-acrylicacid) (dispersion stabilizer). The different concentrations of silver nanofluid (1000-10,000 ppm) were synthesized. The silver particles present in colloidal phase have been characterized by EDX, XRD, UV-visible spectroscopy, Zeta potential and transmission electron microscopy (TEM). The stability as well as thermal conductivity of these nanofluids was determined with a transient hot-wire apparatus, as a lapse of time after preparation. Typically, 10,000 ppm silver nanofluid exhibited rapid increase in the particle size with the passage of time. Thermal conductivity of silver nanofluids increased to 10, 16, and 18% as the amount of silver particles in nanofluid were 1000, 5000, and 10,000 ppm, respectively. After 30 days of preparation, the thermal conductivity of 1000 and 5000 ppm silver nanofluids decreased slightly from 10% and 15% to 9% and 14%, respectively. In addition, the thermal conductivity of 10,000 ppm nanofluid was decreased from 18% to 14% after 30 days. It is very interesting to report that the silver particles were aggregated in early stage of preparation (up to 15 days), which leads to the increase in the size of silver particles. However, no significant change was observed after 15 days which indicates the stability of silver nanofluids.     

液相色谱法测定环氧乙烷和乙二醇装置中气体和液体的醛含量

衍生技术与液相色谱法相结合,将样品与过量的2,4-二硝基苯肼衍生液混合,样品中的甲醛、乙醛分别与2,4-二硝基苯肼发生衍生反应,生成甲醛、乙醛的腙衍生物,用高效液相色谱ODS柱分离,采用DAD检测器在254nm波长下分别测量峰面积,应用标准曲线外标方法计算结果,准确定量测定样品中的甲醛、乙醛含量,解决了环氧乙烷装置反应器出口气中、乙二醇水溶液中以及环氧乙烷和乙二醇产品中的甲醛、乙醛分别定量测定的技术难题,高效、灵敏、准确。     

Solid polymer electrolytes V: microstructure and ionic conductivity of epoxide-crosslinked polyether networks doped with LiClO4

A crosslinked polyether network was prepared from poly(ethylene glycol) diglycidyl ether (PEGDE) cured with poly(propylene oxide) polyamine. Significant interactions between ions and polymer host have been observed for the crosslinked polyether network in the presence of LiClO₄ by means of FT-IR, DSC, TGA, and ⁷Li MAS solid-state NMR. Thermal stability and ionic conductivity of these complexes were also investigated by TGA and AC impedance measurements. The results of FT-IR, DSC, TGA and ⁷Li MAS solid-state NMR measurements indicate the formation of different types of complexes through the interaction of ions with different coordination sites of polymer electrolyte networks. The dependence of ionic conductivity was investigated as a function of temperature, LiClO₄ concentration and the molecular weight of polyether curing agents. It is observed that the behavior of ion transport follows the empirical Vogel-Tamman-Fulcher (VTF) type relationship for all the samples, implying the diffusion of charge carrier is assisted by the segmental motions of polymer chains. Moreover, the conductivity is also correlated with the interactions between ions and polymer host, and the maximum ionic conductivity occurs at the LiClO₄ concentration of [O]/[Li⁺]=15.     

提高凝胶电解质电导率的最新研究进展

综述了一种新型功能高分子材料——凝胶电解质近几年来的研究进展.说明了凝胶电解质的类型:固态聚合物电解质、凝胶聚合物电解质、复合凝胶聚合物电解质.重点阐述了提高凝胶电解质导电性能的方法.主要包括:采用电导率高和化学稳定性高的锂盐,采用交联、共聚和共混等方法对分子结构进行改性,降低结晶性能,添加增塑剂,添加无机填料等.并预...     

铝电解质体系初晶温度、密度和电导率

采用先进的实验技术测定了Na3AlF6-AlF3-Al2O3-CaF2-LiF-NaCl系电解质的初晶温度、密度和电导率. 首先提供了测量的实验数据,接着基于实验数据给出了该体系的初晶温度、密度和电导率的计算公式,并与以前的经验公式作对比,最后从理论上分析了AlF3, Al2O3, LiF和NaCl对电解质物理化学性质的影响. 实验表明,LiF和NaCl能够有效地降低铝电解质的初晶温度并能提高电导率,是十分优良的添加剂,两者配合使用效果良好. 本工作旨在探索新型低温铝电解质组成,为铝电解工业选择适宜的电解质成分提供科学的理论依据.     

分光光度法测定工业用乙二醇二甲醚中微量过氧化物

建立了一种简单、快速、准确的测定乙二醇二甲醚中过氧化物的方法。过氧化物在酸性条件下使碘化钾氧化产生定量碘,产生的碘与淀粉溶液反应生成碘蓝,碘蓝的颜色在一定的浓度范围内符合比尔定律,以此测定过氧化物的总量。结果表明:过氧化物在0.26~40.15μg/mL的浓度范围内,其负对数与吸光度值呈良好的线性关系,相关系数r=0.9993,相对标准偏差为0.97%~1.55%,加标回收率(n=3)为94.76%~98.49%。     

乙二醇快速测定熟料中fCaO

水泥熟料中的fCaO含量过高会直接影响水泥的安定性和强度。过去我厂采用甘油——乙醇法测定需反复煮沸滴定。1990年我厂开始采用了乙二醇快速测定法,提高工效10倍。我们的体会是快速、准确、稳定。 方法及原理:     

电导率法和光度法测定乙醇含水量

本文通过测定不同含水量的二氧化镍乙醇溶液的电导率和吸光度，从而建立了回归方程。并通过显著性检验，发现二氯化镍乙醇溶液的含水量与其电导率成正相关，与其在４２０ｎｍ处的吸光度成负相关，这两种特性可分别应用于乙醇含水量的测定。     

固体聚合物电解质电导率式湿度传感器

以Nafion溶液、二甲基亚砜、碳纸等材料为原料制作成本低廉的湿度传感器，利用感饱和盐溶液定点湿度发生装置，测量不同类型的湿度传感器电导率与相对湿度的关系。结果表明，将氢型膜转化成锂型，加以改性，则会在11％－100％范围内，电导率对数与相对湿度呈良好的线性关系。并通过实验对上述现象做出解释。同时对锂型湿度传感器的性能进行测试。     

全固态聚合物电解质的性能研究

聚合物电解质由于本身的优点,已成为锂离子电池研究的一个热点.聚合物电解质由聚合物、锂盐及添加剂组成,本文综述了聚合物电解质研究的新体系,论述了聚合物电解质中各组分对其性能的影响.     

用ISE法快速测定混合电解质溶液的活度系数

对ＮａＣｌ－ＫＣｌ－Ｈ２Ｏ溶液利用离子选择性电极（ＩＳＥ）的连续滴加法，快速测定出响应ＮａＣｌ的电动势，获得与用文献报道的活度系数计算出的电动势相一致的结果。由此电动势出发可以关联得到混合电解质溶液活度系数的Ｐｉｔｚｅｒ方程的参数，计算ＫＣｌ的活度系数同陆小华－Ｍａｕｒｅｒ提出的电解质溶液模型的预测结果也完全一致，表明本文方法可用于混合电解质溶液活度系数的快速测定。     

乙二醇铝催化酯化法合成聚丁二酸乙二醇酯

聚丁二酸乙二醇酯(PES)具有优异的力学性能和生物降解性能,在可生物降解塑料领域具有广泛的应用前景。以乙二醇铝为催化剂,催化丁二酸和乙二醇直接酯化缩聚合成了高分子量聚丁二酸乙二醇酯(PES)。采用FT-IR和1H-NMR对催化剂和合成聚合物的结构进行了表征,系统分析了催化剂浓度、聚合反应温度和时间对聚合反应的影响。经常压酯交换后获得的预聚体,在240℃条件下,缩聚4 h后,合成PES的特性黏数[η]可达到0.684 dL/g,重均分子量Mw和数均分子量Mn分别可以达到78632和47945,相对分子质量分布系数PDI值为1.64。乙二醇铝体系中获得的PES聚合物分子量与商业锑系和钛系催化体系中合成聚合物分子量相当,具有广泛工业化应用前景。     

Oligomer ethylene glycol based electrolytes for dye‐sensitized solar cell

Oligomer ethylene glycol (O‐EG) based electrolytes without volatile components were prepared and used in dye‐sensitized solar cell (DSSC). The characteristics such as viscosity, ionic conductivity, and ionic activation energy of O‐EG based electrolytes including liquid, gel and solid states were investigated and compared. It is found that the gel and solid O‐EG electrolytes have two E_a values with the changed phase state by going with the increased temperature, and they can increase the onset of applied voltage for generating dark current in DSSCs as from 0.222 V with liquid O‐EG electrolyte to 0.420 V with gel and solid O‐EG electrolytes, which results in the enhanced light‐to‐electricity conversion efficiency from 1.4% with liquid to 1.82% with gel and 1.86% with solid electrolytes. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Morphology and ionic conductivity of thermoplastic polyurethane electrolytes

Thermoplastic polyurethane (TPU) with a mixture of soft segments [poly(ethylene glycol) (PEG) and poly(tetramethylene glycol) (PTMG)], denoted TPU‐M, was prepared as an ion‐conducting polymer electrolyte. TPUs with PEG and PTMG as soft segments were also synthesized individually as polymer electrolytes. The changes in the morphology and ion conductivity of the phase‐segregated TPU‐based polymer electrolytes as a function of the lithium perchlorate concentration were determined with differential scanning calorimetry, Fourier transform infrared spectroscopy, alternating‐current impedance, and linear sweep voltammetry measurements. Both solid and gelatinous polymer electrolytes were characterized in this study. The effect of temperature on conductivity was studied. The conductivity changes revealed the combined influence of PTMG and PEG units in TPU‐M. The swelling characteristics in a liquid electrolyte and the dimensional stability were evaluated for the three TPUs. Because of its dimensional stability and ionic conductivity, the TPU system containing both PEG and PTMG as soft segments was found to be more suitable for electrolyte applications. A room‐temperature conductivity of approximately 1 × 10^?4 was found for TPU‐M containing 50 wt % liquid electrolyte. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1154–1167, 2004     

Electrical conductivity of low-melting electrolytes for aluminium smelting

To determine the electrical conductivity of low-melting electrolytes (AlF₃-rich, e.g. NaF/AlF₃ molar ratio = 1.2), a tube-type cell was used, applying ac-techniques with a sine wave signal with small amplitude in the high frequency range.One melt tested contained 55 mol% NaF and 45 mol% AlF₃ with and without addition of 2 wt.% alumina. Another melt tested contained 55 mol% KF and 45 mol% AlF₃ with and without addition of 2 wt.% alumina. The electrical conductivity data in the molten system can be described by a simple equation of the Arrhenius type:

κ=A e^−B/T