SINGLE-ION CONDUCTIVITY IN POLY (LITHIUM PROPIONATE METHYL SILOXANE)

Poly(lithium propionate methyl siloxane )as a single-ion carrier source was synthesized. The crosslinked film showed lower lithium ionic conductivity at room temperature (about 10~(-10) S/cm). However,the lithium ionic conductivity was obviously increased by blending with high polar polymers such as polyethylene oxide, poly (methylsiloxane - co- ethylene oxide) and poly (methylsiloxane- g- ethylene oxide). In the blend system a high conductivity of 10~(-7)-10~(-5) Scm~(-1) at room temperature was obtained and the single-ion conductivity was deeply influenced by the content of the poly (lithium propionate methyl siioxane). The dc ionic conductivity of the flexible crosslinked films is more stable over time.     

IONIC CONDUCTIVITY IN CROSSLINKED POLY (METHYLSILOXANE-g-ETHYLENE OXIDE) NETWORK FILMS CONTAINING LITHIUM PERCHLORATE

Polymer electrolytes based on poly (methylsiloxane-g-ethylene oxide) and LiClO_4 have been prepared. The network films crosslinked by a crosslinking agent are found to exhibit a considerably high ionic conductivity of about 10~(-4) Scm~(-1) at room temperature and have good flexibility.     

Synthesis of networked polymers with lithium counter cations from a difunctional epoxide containing poly(ethylene glycol) and an epoxide monomer carrying a lithium sulfonate salt moiety

Poly(ethylene glycol)‐based networked polymers that had lithium sulfonate salt structures on the network were prepared by heating a mixture of poly(ethylene glycol) diglycidyl ether (PEGGE), poly(ethylene glycol) bis(3‐aminopropyl) terminated (PEGBA), and an ionic epoxy monomer, lithium 3‐glycidyloxypropanesulfonate (LiGPS). Flexible self‐standing networked polymer films showed high thermal stability, low crystallinity, low glass transition temperature, and good mechanical strength. The materials were ion conductive at room temperature even under a dry condition, although the ionic conductivity was rather low (10^?6 to 10^?5 S/m). The ionic conductivity increased with the increase in temperature to above 1 × 10^?4 S/m at 90 °C. The film samples became swollen by immersing in propylene carbonate (PC) or PC solution of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI). The samples swollen in PC showed higher ionic conductivity (ca.1 × 10^?3 S/m at room temperature), and the samples swollen in LiTFSI/PC showed much higher ionic conductivity (nearly 1 S/m at room temperature). © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3113–3118, 2010     

Safety-enhanced Polymer Electrolytes with High Ambient-temperature Lithium-ion Conductivity Based on ABA Triblock Copolymers

Liquid electrolytes used in lithium-ion batteries suffer from leakage,flammability,and lithium dendrites,making polymer electrolyte a potential alternative.Herein,a series of ABA triblock copolymers(ABA-x)containing a mesogen-jacketed liquid crystalline polymer(MJLCP)with a polynorbornene backbone as segment A and a second polynorbornene-based polymer having poly(ethylene oxide)(PEO)side chains as segment B were synthesized through tandem ring-opening metathesis polymerizations.The block copolymers can self-assemble into ordered morphologies at 200℃.After doping of lithium salts and ionic liquid(IL),ABA-x self-assembles into cylindrical structures.The MJLCP segments with a high glass transition temperature and a stable liquid crystalline phase serve as physical crosslinking points,which significantly improve the mechanical performance of the polymer electrolytes.The ionic conductivity of ABA-x/lithium salt/IL is as high as 10-3 S·cm-1 at ambient temperature owing to the high IL uptake and the continuous phase of conducting PEO domains.The relationship between ionic conductivity and temperature fits the Vogel-Tamman-Fulcher(VTF)equation.In addition,the electrolyte films are flame retardant owing to the addition of IL.The polymer electrolytes with good safety and high ambient-temperature ionic conductivity developed in this work are potentially useful in solid lithium-ion batteries.     

Novel composite polymer electrolytes based on poly(ether-urethane) network polymer and modified montmorillonite

Novel composite solid polymer electrolytes (CSPEs) and composite gel polymer electrolytes (CGPEs) have been prepared. CSPE consists of poly(ether-urethane) network polymer, which is superior to poly(ethylene oxide) in mechanical stability due to its cross-linked structure, modified montmorillonite (MMMT) and LiClO₄, and CGPE with good mechanical strength comprises of the CSPE and LiClO₄–PC (propylene carbonate) solution. The ionic conductivity can be enhanced after the addition of MMMT, and CGPE exhibits ionic conductivity in the order of 10⁻³ S/cm at room temperature. The temperature dependence of the ionic conductivity of the CSPE follows the Vogel–Tamman–Fulcher (VTF) equation. The effects of MMMT on the interactions in these systems and the possible conduction mechanisms are also discussed.     

Dielectric study of hot-pressed nanocomposite polymer electrolytes

Ion-conducting nanocomposite polymer electrolyte films based on poly(ethylene oxide)-NaPO₃ 3: 1 with up to 15 wt % of SiO₂ have been prepared using recently developed hot-press technique instead of conventional solution cast method. With 7 wt % of SiO₂, the film conductivity has been enhanced by an order of magnitude. The materials have been characterized by Fourier transform infrared spectrometry and thermogravimetric analysis. For the composition with the highest conductivity, the temperature dependences of ionic mobility, mobile ions concentration, ionic transference number, and ionic drift velocity have been determined. Dielectric constant and dielectric loss have been measured. The conductivity enhancement has been discussed on the basis of existing theories of dielectrics.     

马来酸酐—醋酸乙烯酯梳状聚合物单阳离子导体的制备及表征

马来酸酐－醋酸乙烯酯交替共聚物以聚乙二醇单醚醇解，得到带有不同长度的聚醚氧侧链的羧酸型梳状聚合物，其碱金属盐在加入适当增塑剂成膜后，可作为聚合物单阳离子导体，其结构以非晶态为主，具有较低的玻璃化转变温度及较好的热稳定性，增塑后的室温电导率最高可达１０－５Ｓ／ｃｍ．研究发现，适当增加侧链的长度有利于提高聚合物膜的离子电导率．此外，还详细探讨了增塑剂、阳离子半径、温度及外加频率等因素对电导率的影响．     

Preparation and properties of ionic‐liquid‐containing poly(ethylene glycol)‐based networked polymer films having lithium salt structures

Ionic‐liquid‐containing polymer films were prepared by swelling poly(ethylene glycol)‐based networked polymers having lithium salt structures with an ionic liquid, 1‐ethyl‐3‐methylimidazolium bis(fluorosulfonyl)imide (EMImFSI), or with an EMImFSI solution of lithium bis(trifluoromethanesulfonyl) imide (LiTFSI). Their fundamental physical properties were investigated. The networked polymer films having lithium salt structures were prepared by curing a mixture of poly(ethylene glycol) diglycidyl ether and lithium 3‐glycidyloxypropanesulfonate or lithium 3‐(glycidyloxypropanesulfonyl)(trifluoromethanesulfonyl)imide with poly(ethylene glycol) bis(3‐aminopropyl) terminated. The obtained ionic‐liquid‐containing films were flexible and self‐standing. They showed high ionic conductivity at room temperature, 1.16–2.09 S/m for samples without LiTFSI and 0.29–0.43 S/m for those with 10 wt % LiTFSI. Their thermal decomposition temperature was above 220 °C, and melting temperature of the ionic liquid incorporated in the film was around ?16 °C. They exhibited high safety due to good nonflammability of the ionic liquid. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Highly ion conductive poly(ethylene oxide)-based solid polymer electrolytes from hydrogen bonding layer-by-layer assembly

We report the development of a solid polymer electrolyte film from hydrogen bonding layer-by-layer (LBL) assembly that outperforms previously reported LBL assembled films and approaches battery integration capability. Films were fabricated by alternating deposition of poly(ethylene oxide) (PEO) and poly(acrylic acid) (PAA) layers from aqueous solutions. Film quality benefits from increasing PEO molecular weight even into the 10(6) range due to the intrinsically low PEO/PAA cross-link density. Assembly is disrupted at pH near the PAA ionization onset, and a potential mechanism for modulating PEO:PAA ratio within assembled films by manipulating pH is discussed. Ionic conductivity of 5 x 10(-5) S/cm is achievable after short exposure to 100% relative humidity (RH) for plasticization. Adding free ions by exposing PEO/ PAA films to lithium salt solutions enhanced conductivity to greater than 10(-5) S/cm at only 52% RH and tentatively greater than 10(-4) S/cm at 100% RH. The excellent stability of PEO/PAA films even when exposed to 1.0 M salt solutions led to an exploration of LBL assembly with added electrolyte present in the adsorption step. Fortuitously, the modulation of PEO/PAA assembly by ionic strength is analogous to that of electrostatic LBL assembly and can be attributed to electrolyte interactions with PEO and PAA. Dry ionic conductivity was enhanced in films assembled in the presence of salt as compared to films that were merely exposed to salt after assembly, implying different morphologies. These results reveal clear directions for the evolution of these promising solid polymer electrolytes into elements appropriate for electrochemical power storage and generation applications.     

红外光谱研究PEO基离子液体聚合物电解质

以聚氧化乙烯(PEO)为聚合物基体, 双三氟甲基磺酸亚酰胺锂(LiTFSI)为锂盐, 加入不同量的离子液体(BMIMPF₆)为增塑剂, 制备离子液体聚合物电解质. 运用发射FTIR光谱技术实时监测所制备聚合物电解质的结构随温度的变化. 结合FTIR透射光谱\, SEM和XRD的研究结果分析了离子液体对离子电导率的影响, 并初步提出离子导电增强机制.     

IONIC CONDUCTIVITY OF POLY(β-ALKOXYCARBONYLETHYLMETHYLSILOXANE)-LiClO4 CROSSLINKED FILMS

Poly (β-carboxyethylmethylsiloxane)-LiClO_4 and poly (β-alkoxylethylmethylsiloxane)-LiClO_4 crosslinked fllms have been prepared. The ionic conductivity of the films depends on the polymer species, concentration of lithium perchlorate, temperature and content of crosslinking agent. The effect of high polar organic solvent 1, 4-butyrolactone on the ionic conductivity and mechanical properties of poly (β-carhoxyethylmethylsiloxane )-LiClO_4 system was also investignied.     

Polymer electrolytes based on room temperature ionic liquid: 2,3-dimethyl-1-octylimidazolium triflate

Room temperature ionic liquid (DMOImTf) based upon 2,3-dimethyl-1-octylimidazolium cation and trifluoromethanesulfonate or triflate (CF(3)SO(3))(-) anion has been synthesized and shows conductivity of 5.68 mS/cm and viscosity of 26.4 cP at 25 degrees C. Ion conducting polymer electrolytes based on polymers (poly(ethylene oxide) (PEO) and polyvinylidenefluoride-co-hexafluoropropylene (PVdF-HFP)) and ionic liquid (DMOImTf) were prepared in film form by the casting technique. The conductivity of polymer electrolytes containing 0.5 M LiCF(3)SO(3) in PEO:DMOImTf taken in equal weight ratio increases with the addition of propylene carbonate (PC) while its mechanical stability improved by dispersing nanosize fumed silica. However, polymer electrolytes containing PVdF-HFP and ionic liquid show a high value of conductivity (10(-4)-10(-3) S/cm) alongwith better mechanical stability.     

Syntheses and characterizations of soft‐segment ionic polyurethanes

Novel soft‐segment ionic polyurethane (linear and crosslinking) have been prepared based up on sodium sulfonate–side chains poly(ethylene oxide) (SPEO). SPEO was synthesized by grafting the sodium sulfonate onto the chain of poly(ethylene oxide) with molecular weights of 400, 600, 800, and 1000. The SPEO and the ionic polyurethane were characterized by elemental analysis, ¹H‐NMR, ¹³C‐NMR, gel permeation chromatography, and impedance analysis. The effect of plasticizer on the ionic conductivity of the polyurethane was also investigated. These solid polymer electrolytes possess a higher ionic conductivity (about 10⁻⁶ S/cm at room temperature) than the corresponding sulfonated hard‐segment polyurethane electrolytes. The presence of the hydroxyl group in the electrolyte tends to lower the ionic conductivity. Crosslinking of polyurethane results in the enhancement of the dimensional stability, while maintaining the same level of the ionic conductivity. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 837–845, 1999     

聚苯并咪唑-锂盐-聚乙二醇单甲醚共混全固态聚合物电解质的制备及性能

使用共混后浇铸成膜的方法,制备了聚苯并咪唑-锂盐-聚乙二醇单甲醚组成的锂离子电池共混全固态聚合物电解质。通过傅里叶红外光谱(FT-IR)、X射线衍射(XRD)、差示扫描量热(DSC)、拉伸与交流阻抗测试表征了共混全固态电解质的结构与性能。研究了不同锂盐以及各组分含量对共混全固态电解质的力学性能与电导率的影响。结果表明:聚苯并咪唑与聚乙二醇单甲醚之间存在氢键;共混全固态电解质中聚乙二醇单甲醚处于无定形态;锂盐的加入使聚乙二醇单甲醚的玻璃化转变温度下降;聚乙二醇单甲醚含量越高,共混膜强度越低,电导率越高,并且使用三氟甲磺酸锂作为锂盐时其电导率最高,室温下可以达到3.58×10~(-5) S/cm,高温下可以达到3.3×10~(-3) S/cm,高温下满足对锂离子电池的使用需求。     

Effect of Tacticity of Poly(Methyl Methacrylate) on Conductivity of Poly(Ethylene Oxide)-Poly(Methyl Methacrylate) Blend-Based Polymeric Electrolytest

Abstract

Polymer electrolytes based on blends of poly(ethylene oxide) (PEO) with various stereoisomers of poly(methyl methacrylate) (PMMA) were studied by means of impedance spectroscopy and DSC. It was found that isotactic poly(methyl methacrylate) (1PMMA)-based electrolytes exhibit ambient temperature conductivities at least one order of magnitude higher than the electrolytes containing other stereoisomers of PMMA. The highest value of room temperature conductivity equal to 9 × 10^?5 S/cm was measured for a sample containing 30 wt% IPMMA. The effect observed results from the presence of a flexible amorphous phase in PEO-IPMMA blends which is favorable for fast ionic transport. A small increase of ionic conductivity with decreasing molecular weight of the added atactic poly(methyl methacrylate) was also observed.     

Ion gels prepared by in situ radical polymerization of vinyl monomers in an ionic liquid and their characterization as polymer electrolytes

To realize polymer electrolytes with high ionic conductivity, we exploited the high ionic conductivity of an ionic liquid. In situ free radical polymerization of compatible vinyl monomers in a room temperature ionic liquid, 1-ethyl-3-methyl imidazolium bis(trifluoromethane sulfonyl)imide (EMITFSI), afforded a novel series of polymer electrolytes. Polymer gels obtained by the polymerization of methyl methacrylate (MMA) in EMITFSI in the presence of a small amount of a cross-linker gave self-standing, flexible, and transparent films. The glass transition temperatures of the gels, which we named "ion gels", decreased with increasing mole fraction of EMITFSI and behaved as a completely compatible binary system of poly(methyl methacrylate) (PMMA) and EMITFSI. The temperature dependence of the ionic conductivity of the ion gels followed the Vogel-Tamman-Fulcher (VTF) equation, and the ionic conductivity at ambient temperature reached a value close to 10(-2) S cm(-1). Similarly to the behavior of the ionic liquid, the cation in the ion gels diffused faster than the anion. The number of carrier ions, calculated from the Nernst-Einstein equation, was found to increase for an ion gel from the corresponding value for the ionic liquid itself. The cation transference number increased with decreasing EMITFSI concentration due to interaction between the PMMA matrix and the TFSI(-) anion, which prohibited the formation of ion clusters or associates, as was the case for the ionic liquid itself.     

Investigations on poly(methyl methacrylate)-poly(ethylene oxide) hybrid polymer electrolytes with dioctyl phthalate, dimethyl phthalate and diethyl phthalate as plasticizers

Plasticizers can be used to change the mechanical and electrical properties of polymer electrolytes by reducing the degree of crystallinity and lowering the glass transition temperature. The transport properties of gel-type ionic conducting membranes consisting of poly(ethylene oxide) (PEO), poly(methyl methacrylate) (PMMA), LiClO₄ and dioctyl phthalate, diethyl phthalate or dimethyl phthalate (DMP) are studied. The polymer films are characterized by X-ray diffraction, Fourier transform infrared and impedance spectroscopic studies. It is found that the addition of DMP as the plasticizer in the PEO-PMMA-LiClO₄ polymer complex favours an enhancement in ionic conductivity. The maximum conductivity value obtained for the solid polymer electrolyte film at 305 K is 3.529×10^{– 4} S cm^–1. Electronic Publication     

Single‐Walled Carbon Nanotubes in Highly Viscous Media: A Comparison between the Dispersive Agents [BMIM][BF4], L121, and Triton X‐100

Dispersions of single‐walled carbon nanotubes (SWNTs) have been prepared by using the room‐temperature ionic liquid [BMIM][BF₄] (1‐butyl‐3‐methylimidazolium tetrafluoroborate), the triblock copolymer Pluronic L121 [poly(ethylene oxide)₅‐poly(propylene oxide)₆₈‐poly(ethylene oxide)₅] and the non‐ionic surfactant Triton X‐100 (TX100) in the pure state. The size of the SWNTs aggregates and the dispersion degree in the three viscous systems depend on the sonication time, as highlighted by UV/Vis/NIR spectroscopy and optical microscopy analysis. A nonlinear increase in conductivity can be observed as a function of the SWNTs loading, as suggested by electrochemical impedance spectroscopy. The generation of a three‐dimensional network of SWNTs showing a viscoelastic gel‐like behavior above a critical percolation concentration has been found at 25 °C in all the investigated systems by oscillatory rheology measurements.     

Electrical conduction in olefin oxide polymers

The electrical conductivities in vacuo of poly(ethylene oxide) and two higher olefin oxide polymers have been found to be ～9 orders higher than for other saturated organic polymers. The possibility of ionic transport resulting from the presence of impurities (including water) has been eliminated, and it is proposed that an inherent ionic process is operative, involving the generation of protons and then subsequent transport by a handing-on process. The two general requirements are the presence of proton-accepting atoms (in this case oxygen) in the polymer chains; and proximity to the melting point to ensure adequate chain-mobility. These requirements are met by poly(ethylene oxide), poly(trimethylene oxide), and poly(tetramethylene oxide), which are all close to their melting points at room temperature. poly(methylene oxide), with a melting point of ～180°C., on the other hand, has the low conductivity of a typical insulator.     

Effects of gamma and electron beam irradiation on polymer electrolytes

Polymer electrolytes based on poly(ethylene oxide) and lithium salts have been widely studied in recent years. In order to enhance the room temperature ionic conductivity of PEO-LiX complexes, various techniques, such as addition of plasticizers and crown ether, and also irradiation by γ and electron beams have been investigated. The enhancement of the conductivity by irradiation has been accounted for the decreasing of the crystallinity of PEO-LiX. We reviewed these results and have investigated the degradation processes of PEO using Tb³⁺ fluorescence probes. We have also studied on the effects of irradiation of polymers such as poly(acrylic acid) (PAA), poly(methacrylic acid) (PMA) and PEO using Tb⁺³ fluorescence probe. Various monomers containing SO₃H and COOH have been grafted on poly(ethylene oxide) using irradiation technique. The structures and ionic conductivities of Li and Na salts of irradiated products were investigated in detail.