PEO-based polymer electrolytes

Like a liquid solvent, poly(ethylene oxide) dissolves a wide variety of inorganic salts. Ionic conductivity occurs in the amorphous region of the polymer and typically both anions and cations are mobile to some extent. This paper discusses the preparation, thermal behaviour and ionic transport of thin cast films of PEO-based electrolytes containing monovalent and divalent cations. The techniques that shed light on the structure-conductivity relationship are emphasized. The temperature and composition dependence of conductivity is also considered. Finally, attention has been paid to the possible uses of these polymeric electrolytes in solid-state electrochemical devices such as primary and secondary batteries, electrochromic displays and sensors.     

急-锂单离子导电聚合物电解质的制备及其界面稳定性

以（对苯乙烯磺酸基）三氟甲基磺酰亚胺锂（LiSTFSI）、聚乙二醇甲醚甲基丙烯酸酯(PEGM)和甲基丙烯酸四氟丙酯（TFMA）、甲基丙烯酸八氟戊酯（OFMA）、甲基丙烯酸十二氟庚酯(DFMA)为单体,合成了三种锂单离子导电聚合物电解质隔膜。采用FTIR、SEM、EIS和LSV对隔膜进行了表征。研究表明,所合成的电解质膜具有较高的离子电导率（90 ℃,10-5 S/cm）、较宽的电化学稳定窗口（4.5 V）和高的锂离子迁移数（≈1）。将隔膜组装CR 2025扣式电池进行恒电位间歇滴定法（PITT）测试,结果显示电解质隔膜拥有较高的锂离子扩散系数（60 ℃,10-9 cm2/s）。经热处理后,电解质膜与锂金属的界面稳定性得到明显提升,X射线光电子能谱（XPS）测试表明这与含氟侧链基团在聚合物电解质的表面富集有关。     

Effect of succinonitrile and nano-hydroxyapatite on ionic conductivity and interfacial stability of polyether-based plasticized nanocomposite polymer electrolytes (PNCSPE)

A series of novel plasticized nanocomposite solid polymer electrolytes (PNCSPE) consisting of polyethylene oxide as polymer host, lithium bisoxalatoborate as salt with different weight ratios of succinonitrile and nano-hydroxyapatite was prepared by membrane hot-press technique. The electrical property of PNCSPE was investigated by AC impedance analysis. The migration of lithium ion in the polymer matrix was confirmed from cyclic voltammetry study. The incorporation of different compositions of filler and plasticizer in the polymer matrix significantly enhanced the amorphous nature resulted in increase in ionic conductivity of PNCSPE. The maximum ionic conductivity was found to be in the order of 10^?3.1 S/cm.     

Synthesis and electrochemical characterization of PEO-based polymer electrolytes with room temperature ionic liquids

New gel polymer electrolytes containing 1-butyl-4-methylpyridinium bis(trifluoromethanesulfonyl)imide (BMPyTFSI) ionic liquid are prepared by solution casting method. Thermal and electrochemical properties have been determined for these gel polymer electrolytes. The addition of BMPyTFSI to the P(EO)₂₀LiTFSI electrolyte results in an increase of the ionic conductivity, and at high BMPyTFSI concentration (BMPy⁺/Li⁺ = 1.0), the ionic conductivity reaches the value of 6.9 × 10⁻⁴ S/cm at 40 °C. The lithium ion transference numbers obtained from polarization measurements at 40 °C were found to decrease as the amount of BMPyTFSI increased. However, the lithium ionic conductivity increased with the content of BMPyTFSI. The electrochemical stability and interfacial stability for these gel polymer electrolytes were significantly improved due to the incorporation of BMPyTFSI.     

Ionic conductivity and interfacial properties of polymer electrolytes based on PEO and boroxine ring polymer

Blended polymer electrolytes based on poly(ethylene oxide) (PEO) and boroxine ring polymer (BP) solvated with lithium triflate were formulated and evaluated. Compared to PEO–salt polymer electrolyte, ionic conductivities of blended polymer electrolytes were two orders of magnitude higher in a low‐temperature range; as well, lithium transference numbers were increased to ～ 0.4. These were due to the increased mobility and anion trapping of boroxine rings. BP also exhibited the stabilizing effect on lithium–polymer electrolyte interface, and a reduced interfacial resistance between lithium metal and the polymer electrolyte was found with increasing of BP content. Polymer electrolytes based on PEO and BP are suitable for use in lithium secondary battery. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 17–21, 2002; DOI 10.1002/app.10090     

Effect of calix[6]pyrrole anion receptor addition on properties of PEO-based solid polymer electrolytes doped with LiTf and LiTfSI salts

In this article the impact of anion receptor (1,1,3,3,5,5-meso-hexaphenyl-2,2,4,4,6,6-meso-hexamethyl-calix[6]pyrrole) on physicochemical and ion transport properties of poly(ethylene oxide)-salt composites is discussed. Two salts, lithium triflate and lithium bis(trifluoromethane) sulfonamide, were tested. It is shown that addition of the anion receptor significantly increases glass transition temperature of the composite suggesting changes in the velocity of segmental motions of the polymeric matrix. Also some discrepancies between crystallinity of the electrolyte measured by means of DSC and the one measured by means of XRD for lithium triflate containing electrolytes are discussed. It is proved that the influence of the anion receptor on electrolyte properties depends on the coordinating properties of the anion. In consequence this two structurally similar anions are found to reveal opposite behavior. In systems containing LiTf significant changes in properties are observed upon receptor addition. Contrastively, LiTfSI does not interact with receptor and obtained samples exhibit non-homogenous structure with consequent receptor participation.     

Effect of tacticity of poly(methyl methacrylate) on interfacial region with silica in polymer nanocomposite

The effect of tacticity on the interfacial region between poly(methyl methacrylate) (PMMA) and silica in a PMMA/silica nanocomposite was investigated by differential scanning calorimetry (DSC), Fourier-transform infrared spectroscopy (FT-IR), and X-ray diffraction (XRD). The glass transition temperature (T_g) values of the syndiotactic (st-) and atactic (at-) PMMA/silica nanocomposites are higher than those of the neat PMMA. Conversely, the T_g of the isotactic (it-) PMMA/silica nanocomposite is slightly higher than that of the neat it-PMMA. DSC and XRD results suggest that the restriction of the PMMA chain mobility in the silica nanoparticle interfacial region heightens as the syndiotactic content increases. FT-IR results show that this phenomenon is caused by the interaction between the carbonyl group of PMMA and the silanol group on the silicon dioxide surface. Therefore, it can be concluded that the syndiotactic-rich PMMA has a significantly different molecular mobility from that of the neat PMMA in the interfacial region with silica nanoparticle surface than isotactic-rich PMMA.     

Effect of gel electrolytes containing silica nanoparticles on aluminum corrosion

We have investigated corrosion of aluminum current collectors in electrolytes containing LiTFSI salt by chronopotentiometry, cyclic voltammetery, chronoamperometry, electrochemical impedance spectroscopy, and optical microscopy. Open-circuit potentials for cells with gel electrolytes containing silica nanoparticles are relatively stable in comparison to the corresponding baseline liquid, which suggests that the Al/electrolyte interface is more stable in presence of silica nanoparticles. Cyclic voltammetery and chronoamperometry data show that the current density for Li/electrolyte/Al cells with gel electrolytes containing fumed silica was less than that for baseline liquid electrolyte. The Nyquist plot for liquid electrolyte after chronoamperometry is semicircular-like, that is a corrosion reaction occurred. After cell disassembly, black particulates are evident and pits are observed on the aluminum foil. In comparison, no corrosion products are observed for cells containing gel electrolytes, and the Nyquist plots indicate that corrosion does not occur appreciably. Gel electrolytes produce impedance spectra with a large phase lag over a wide frequency range, which is not observed for the baseline liquid electrolyte. These phenomena may be interpreted as a good film-coating behavior associated with gel electrolytes, which results in a lower aluminum corrosion rate.     

Effect of oligomer on dye-sensitized solar cells employing polymer electrolytes

The effect of oligomer (M _n =400–500 g/mol) on dye-sensitized solar cells (DSSC) employing polymer electrolytes consisting of poly(epichlorohydrin-co-ethylene oxide) (Epichlomer), LiI, 1-methyl-3-propylimidazolium iodide (MPII) and I₂ is investigated. Five kinds of oligomer, poly(ethylene glycol) (PEG, M _n =400 and 1,000 g/mol), poly(ethylene glycol) dimethyl ether (PEGDME), poly(propylene glycol) (PPG) and poly(ethylene glycol) diglycidyl ether (PEGDGE), were introduced to elucidate the role of terminal groups and chain length. The coordinative interactions and structures of polymer electrolytes were characterized by FT-IR spectroscopy and X-ray diffraction (XRD). The improved interfacial contact between the electrolytes and the electrodes by the oligomer addition was confirmed using a field-emission scanning electron microscope (FE-SEM). The electrolytes exhibited ionic conductivities on the order of 10^?4 S/cm, but PEGDGE electrolyte showed much lower value (～10^?8 S/cm). As a result, the energy conversion efficiency of DSSC was significantly affected by the oligomer. For example, the DSSC employing PEGDME with methyl terminal groups exhibited 3.95% at 100 mW/cm², which is 200-fold higher than that employing PEGDGE.     

Ionic conductivity and physical stability study of gel nework polymer electrolytes

Gel polymer electrolytes (GPE) were prepared by a crosslinking reaction between poly(ethylene glycol) and a crosslinking agent with three isocyanate groups in the presence of propylene carbonate (PC) and ethylene carbonate (EC) or their mixture, and their ionic conducting behavior was carefully investigated. When the plasticizer amount was fixed, the ionic conductivity was greatly influenced by the nature of plasticizers. It was found that the conductivity data followed the Arrhenius equation in the GPE. Whatever plasticizer was used, a maximum ambient conductivity was found at a salt concentration near [Li⁺]/[EO] equal to 0.20. The physical stability of GPE was studied qualitatively by weight loss of GPE under pressure. It was shown that the stability was greatly affected by the network structure of the GPE and the most stable one in our research was the GPE containing the PEO₁₀₀₀ segment, which has a strong interaction between network and plasticizers. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2957–2962, 2000     

丙烯酰胺聚合物与发泡剂对油水界面性质及乳状液稳定性的影响

用界面张力仪、表面黏弹性仪和Zeta电位仪研究了胜利埕东油田聚合物强化泡沫复合驱中聚合物和/或发泡剂质量浓度对油水界面特性及乳状液稳定性的影响.结果表明,随聚合物质量浓度增加,模拟水与原油模拟油间油水界面张力、界面剪切黏度和油滴表面的Zeta电位绝对值增大;而随发泡剂质量浓度增加,模拟水与原油模拟油间的界面张力降低,界面剪切黏度有所增加,但变化幅度很小,油滴表面的Zeta电位绝对值增大;原油模拟油与含聚合物和发泡剂的模拟水间所形成的W/O乳状液稳定性随聚合物和/或发泡剂质量浓度增加而增强.     

Gel-based composite polymer electrolytes with novel hierarchical mesoporous silica network for lithium batteries

In the present work, novel gel-based composite polymer electrolytes for lithium batteries were prepared by introducing a hierarchical mesoporous silica network to the poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP)-based gel electrolytes. As compared with the PVDF-HFP-based gel electrolytes with/without conventional nano-sized silica fillers, the novel electrolytes have shown more homogeneous microstructure, higher ionic conductivity and better mechanical stability, which could be caused by the strong silica network and the effective interactions among the polymer, the liquid electrolytes and the silica. Moreover, the cell with this kind of electrolytes could achieve a discharge capacity as much as 150 mAh g⁻¹ at room temperature (LiCoO₂ as the cathode active material), with high Coulomb efficiency.     

Effect of the silica precursor on the conductivity of hectorite-derived polymer nanocomposites

New hectorite and organo-hectorite clays have been prepared using different silica sol sources, in order to examine the importance of sol particle size, pH, and surface chemistry on the final matrix. Polymer-clay nanocomposites (PCN) are prepared by intercalating polyethylene oxide in the clay layers of lithium hectorites. The resulting films are physically and electrochemically evaluated. Conductivity values, activation energies, and lithium transference numbers indicate that the PCNs are single ion conductors with transference numbers close to unity. The activation energies are in the range of 0.02 V, two orders of magnitude lower than the conventional polymer electrolytes.     

Effect of PBMA on PVC‐based polymer blend electrolytes

Poly(vinyl chloride) (PVC)—poly(butyl methacrylate) (PBMA) blended polymer electrolytes with lithium perchlorate (LiClO₄) as the complexing salts are prepared by solution casting technique. The addition of PBMA into PVC matrix is found to induce considerable changes in physical and electrical properties of the polymer electrolytes. Addition of PBMA into PVC matrix is found to increase the conductivity by two orders of magnitude (1.108 × 10^?5 S cm^?1) when compared with that of the pristine PVC polymer electrolyte (10^?7 S cm^?1). Structural, thermal, mechanical, morphological, and polymer–salt interactions are ascertained from X‐ray diffraction (XRD), thermogravimetry/differential thermal analysis (TG/DTA), mechanical analysis, scanning electron microscope (SEM), and Fourier transform infrared spectroscopy (FTIR) respectively. A thermal stability upto 250 °C is asserted from the TG/DTA analysis. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 44939.     

Effect of interfacial attraction on intercalation in polymer/clay nanocomposites

In order to examine the adhesive behavior of a polar polymer between hydrophilic clay layers, the so‐called glue effect, a clay intercalation by an ethylene–vinyl alcohol (EVOH) copolymer, which was capable of strong hydrogen bonding with the silicate surface of clay, was prepared by the melt intercalation technique and compared with a clay nanocomposite containing styrene–acrylonitrile (SAN) copolymer of less polar interaction energy in terms of the morphology and mechanical properties. Although initial penetration of the guest polymer into the gallery of the host clay occurred more rapidly for EVOH because of its strong hydrophilic nature, the dissociation of clay nanoplatelets was better developed for SAN with less polar interaction with clay, well evidencing the fact that the glue effect effectively affects the intercalation behavior of polymer/clay nanocomposites. However, the mechanical properties of the EVOH/clay nanocomposite were superior to those of SAN/clay nanocomposites. Although dissociation of respective silicate layers was poor for EVOH/clay nanocomposites, strong attractive energy stabilizes the interface between inorganic nanoparticles and the polymer matrix much more effectively, resulting in higher mechanical properties. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2749–2753, 2006     

Study of the interfacial stability of PVdF/HFP gel electrolytes with sub-micro- and nano-sized surface-modified silicas

The aim of the presented work was to perform a preliminary study of the physicochemical and interfacial properties of hybrid organic-inorganic gel electrolytes for Li-ion batteries based on the PVdF/HFP polymeric matrix and surface-modified silicas. Two types of silica fillers of different grain sizes (>500 nm and ∼100 nm) were used as additives. The silica particles were modified by two different functional groups, i.e. methacryloxy and vinyl ones. The gel electrolytes based on PVdF/HFP copolymer were prepared according to the so-called Bellcore two-step process. The motivation of the present work was to study more deeply those systems in terms of morphology by means of scanning electron microscopy techniques. Fillers modified with identical functional groups but differing fundamentally in the manufacturing processes were compared in terms of the impact on morphology and electrochemical performance of the resulting membranes. Interfacial properties were examined by means of impedance spectroscopy technique using Swagelok-type cells with two lithium electrodes.     

聚合物对原油乳状液稳定性的影响

为了全面研究聚合物驱对孤岛油田原油乳状液稳定性的影响,通过结合瓶试法和光散射法研究驱油剂对原油乳状液稳定性的影响。用瓶试法可以得到宏观脱水率,用光散射法可以得到稳定性系数、平均粒径变化、澄清度的变化以及出水层峰的厚度等。结果表明,随着原油乳状液中聚合物浓度的增加,原油乳状液的脱水率减少,稳定性系数减小,原油乳状液平均粒径减小,破乳后脱出水澄清度减小,出水层峰的厚度减小。     

First international symposium on polymer electrolytes

We review the effects of temperature on conductance and viscosity in the liquid state of vitreous ionic conductors and show how differences may be best understood by comparison of relaxation times for electrical and mechanical stresses acting on liquid or glassy states of the material. This leads to the definition of a conductivity/viscosity mode decoupling index, useful as a figure of merit for the solid electrolyte. In applying the same approach to polymer electrolyte systems a problem is encountered due to the molecular weight dependence of the viscosity. This is resolved by deriving a ‘monomer’ shear relaxation time for the polymer electrolyte solution and showing that this quantity corresponds closely with the ‘local’ mechanical relaxation time obtained from light scattering studies (which is a molecular weight independent quantity for pure polypropylene oxide and other polymers of low T_g). Comparison of the electrical relaxation times of the polymer solution with the ‘local’ (or ‘matrix’) relaxation times then shows that the relationship found for superionic glass-forming systems is inverted in the case of polymer electrolytes. The latter have fractional decoupling indexes which may be interpreted in terms of serial coupling phenomena; i.e. ions must first decouple from their partner ions (in ion pairs), or from their intramolecular solvation states, before they can contribute to conductivity relaxation which is itself coupled to the local polymer matrix relaxation. An extreme case is illustrated using the weak electrolyte, lithium acetate, for which the decoupling index is ～6 × 10^?5.     

Proton-conducting polymer electrolytes based on methacrylates

Proton-conducting polymer electrolytes based on methacrylates were prepared by direct, radical polymerization of ethyl (EMA), 2-ethoxyethyl (EOEMA), and 2-hydroxyethyl methacrylate (HEMA). Samples with embedded solutions of phosphoric acid in propylene carbonate (PC), γ-butyrolactone (GBL), N,N-dimethylformamide (DMF) and their mixtures were studied using impedance, voltammetrical and thermogravimetric methods. Membranes of long-term stability exhibit ionic conductivity up to 6.7 × 10⁻⁵ S cm⁻¹ at 25 °C reached for the sample PEMA-PC-H₃PO₄ (31:42:27 mol.%). The accessible electrochemical potential window is 2.2-3 V depending on the working electrode material (glassy carbon or platinum). The thermogravimetric analysis shows that the membranes are thermally stable up to 110-130 °C.     

Electrorheological fluids based on polymer electrolytes

The phenomenon of electrorheological activity taking part in so called electrorheological fluids (ERFs) relies on strong and reversible changes of fluid viscosity upon application of electric field and finds interesting technical applications. ERFs typically comprise dispersions of polarisable solid particles in liquid matrices. The paper describes studies on complexes of polyacrylonitrile with various salts of alkaline elements. The materials in a powder form were dispersed in silicone oil as well as in active matrices containing a liquid crystalline polymer. It was found that these novel systems were substantially anhydrous and electrorheologically active. The observed ER effect was relatively high and accompanied by very low current consumption. The magnitude of the ER effect was correlated with bulk ionic conductivity of the studied materials. The optimal bulk conductivity giving the highest ER effect at reasonably low currents amounted to about 10⁻⁵ S/cm. Higher conductivities resulted in higher currents only and saturation of the yield stress values. It was also shown that dispersions of the polymer complexes in a solution of poly(n-hexyl isocyanatye) in xylene manifested enhanced ER activity.