Novel PEO-based solid composite polymer electrolytes with inorganic–organic hybrid polyphosphazene microspheres as fillers

Novel solid-state composite polymer electrolytes based on poly (ethylene oxide) (PEO) by using LiClO₄ as doping salts and inorganic–organic hybrid poly (cyclotriphosphazene-co-4,4′-sulfonyldiphenol) (PZS) microspheres as fillers were prepared. Electrochemical and thermal properties of PEO-based polymer electrolytes incorporated with PZS microspheres were studied. Differential scanning calorimetry (DSC) results showed there was a decrease in the glass transition temperature of the electrolytes and the crystallinity of the samples in the presence of the fillers. Maximum ionic conductivity values of 1.2 × 10⁻⁵ S cm⁻¹ at ambient temperature and 7.5 × 10⁻⁴ S cm⁻¹ at 80° were obtained and lithium ion transference number was 0.29. Compared with traditional ceramic fillers such as SiO₂, the addition of PZS microspheres increased the ionic conductivity of the electrolytes slightly and led to remarkable enhancement in the lithium ion transference number.     

Effect of an Nb2O5 nanolayer coating on ZnO electrodes in dye-sensitized solar cells

Nanostructured porous zinc oxide electrodes for use in dye-sensitized solar cells (DSSCs) were coated with thin niobium oxide layers by using sol–gel transformation of niobium pentaethoxide in air. Coating solutions were prepared by mixing niobium pentaethoxide and ethanol. A dip-coating technique was adopted at a low withdrawal speed of 100 μm s⁻¹. The coated electrodes were then heat-treated at temperatures between 400 and 600 °C. The presence of niobium in the coated electrodes was confirmed by X-ray photoelectron spectroscopy. As expected, the niobium oxide layers worked as an energy barrier between the ZnO electrode and electrolyte. Open-circuit voltage (V_OC) of the cells using the coated electrodes was then enhanced up to 0.768 V, which was attributable to the suppression of the recombination of photogenerated electrons with oxidized species in electrolytes. An additional benefit of the coating was that grain growth of ZnO particles in the electrodes was hindered and short-circuit photocurrent density (J_SC) was kept relatively high due to large amounts of adsorbed dye. An overall light-to-electricity conversion efficiency was increased to a maximum of 5.19%, indicating that the proper coating technique was the key for improving the performance of ZnO-based DSSCs.     

Morphology,crystallinity, and electrochemical properties of in situ formed poly(ethylene oxide)/TiO2 nanocomposite polymer electrolytes

A method to produce nanocomposite polymer electrolytes consisting of poly(ethylene oxide) (PEO) as the polymer matrix, lithium tetrafluoroborate (LiBF₄) as the lithium salt, and TiO₂ as the inert ceramic filler is described. The ceramic filler, TiO₂, was synthesized in situ by a sol–gel process. The morphology and crystallinity of the nanocomposite polymer electrolytes were examined by scanning electron microscopy and differential scanning calorimetry, respectively. The electrochemical properties of interest to battery applications, such as ionic conductivity, Li⁺ transference number, and stability window were investigated. The room‐temperature ionic conductivity of these polymer electrolytes was an order of magnitude higher than that of the TiO₂ free sample. A high Li⁺ transference number of 0.51 was recorded, and the nanocomposite electrolyte was found to be electrochemically stable up to 4.5 V versus Li⁺/Li. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2815–2822, 2003     

Solid-state mechanochemical synthesis of CsHSO4 and 1,2,4-triazole inorganic–organic composite electrolytes for dry fuel cells

Inorganic–organic composite electrolytes for use in dry fuel cells were synthesized from CsHSO₄ (CHS) and 1,2,4-triazole (Tz). CHS and Tz were mechanochemically treated in a dry nitrogen atmosphere to obtain composites with xCHS·(100 − x)Tz, where x is the amount (mol) and was varied in increments of 10 between 90 and 50. Structural investigation of the composites indicated that chemical interactions occurred between CHS and Tz after solid-state mechanochemical treatment. The proton conductivity of the composite electrolytes was largely increased by introduction of Tz, particularly in the low temperature region. The composite with x = 80 showed high proton conductivity (6.0 × 10⁻⁴ to 1.60 × 10⁻³ S cm⁻¹) over a wide temperature range (60–160 °C) in a dry atmosphere. These observations suggest that proton transfer in the CHS and Tz composite systems includes the proton-hopping mechanism and self-dissociation. This phenomenon probably supports proton diffusion, especially in low temperature regions.     

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.     

Lithium transference number measurements and complex abilities in anion trapping triphenyloborane-poly(ethylene oxide) dimethyl ether-lithium trifluoromethanesulfonate composite electrolyte

In this paper we report the combined, positive effect of triphenyloborane (BPh₃) additive on conductivity and lithium cation transference numbers in poly(ethylene oxide) dimethyl ether (PEODME)-lithium trifluoromethanesulfonate (LiCF₃SO₃, LiTf) electrolytes. The transport mechanism is discussed on the basis of impedance measurements, restricted diffusion t⁺ measurements, ionic association semi-empirical quantitative estimation and spectroscopic studies. A substantial increase in the lithium transference number values in triphenylborane enriched composite electrolytes was observed in comparison with the pure PEODME-LiCF₃SO₃ electrolyte. This effect is assisted by ionic conductivity enhancement.     

A new carbon nanotubes (CNTs)–poly acrylonitrile (PAN) composite electrolyte for solid state dye sensitized solar cells

A new carbon nanotube (CNTs)–poly acrylonitrile (PAN) composite electrolyte was prepared by the thermal polymerization of acrylonitrile (AN) with CNTs for solid-state dye sensitized solar cells (DSSCs). It was found that the uniform CNT–PAN composite was formed due to the thermal polymerization of AN on CNTs. The strong bonding between CNTs and PAN could be confirmed by the characterization of XPS and Raman spectroscopy, resulting in the lowering of crystallinity and the increasing the ionic conductivity of composite electrolytes. On comparison with bare CNTs and the other composite electrolytes, the formation of triiodide (I₃⁻) ions in CNT–PAN composite electrolytes was drastically increased which was expected from the high ionic conductivity of electrolyte via I₃⁻/I⁻ redox couple. DSSCs fabricated with CNT–PAN composite electrolytes achieved relatively high conversion efficiency of 3.9% with an open circuit voltage (V_OC) of 0.57 V, short circuit current density (J_SC) of 10.9 mA/cm² and fill factor of 63.6%, which attributed to supply the higher extent of I₃⁻ ions from CNT–PAN composite electrolyte during the charge transport process.     

Effect of surface modified porous inorganic-organic hybrid polyphosphazene nanotubes on the properties of polyethylene oxide based solid polymer electrolytes

2-(2-methyloxyethoxy)ethanol modified poly (cyclotriphosphazene-co-4,4′-sufonyldiphenol) (PZS) nanotubes were synthesized and solid composite polymer electrolytes based on the surface modified polyphosphazene nanotubes added to PEO/LiClO₄ model system were prepared. Differential Scanning Calorimetry (DSC) and Scanning Electron Microscopy (SEM) were used to investigate the characteristics of the composite polymer electrolytes (CPE). The ionic conductivity, lithium ion transference number and electrochemical stability window can be enhanced after the addition of surface modified PZS nanotubes. The electrochemical investigation shows that the solid composite polymer electrolytes incorporated with PZS nanotubes have higher ionic conductivity and lithium ion transference number than the filler SiO₂. Maximum ionic conductivity values of 4.95 × 10⁻⁵ S cm⁻¹ at ambient temperature and 1.64 × 10⁻³ S cm⁻¹ at 80 °C with 10 wt % content of surface modified PZS nanotubes were obtained and the lithium ion transference number was 0.41. The good chemical properties of the solid state composite polymer electrolytes suggested that the inorganic-organic hybrid polyphosphazene nanotubes had a promising use as fillers in solid composite polymer electrolytes and the PEO₁₀-LiClO₄-PZS nanotubes solid composite polymer electrolyte can be used as a candidate material for lithium polymer batteries.     

Synthesis and characterization of a new hyperbranched organic–inorganic solid polymer electrolyte with cyanuric chloride as a core element

A new hyperbranched organic–inorganic hybrid electrolyte based on the use of 2,4,6-trichloro-1,3,5-triazine (cyanuric chloride, CC) as the coupling core to couple with oligo(oxyalkylene)-amines, followed by condensation with (3-glycidoxypropyl)-trimethoxysilane (GLYMO) and complexed with LiClO₄, has been prepared and characterized. The Vogel–Tamman–Fulcher (VTF) like conductivity behavior is observed in the present organic–inorganic hybrid electrolytes with a maximum ionic conductivity value of 4.4 × 10⁻⁵ S cm⁻¹ at 30 °C. Multinuclear NMR techniques are used to provide a microscopic view for the specific interaction between the polymer chains and Li⁺ cations and their dynamic behaviors. The results of 2D ¹H–¹³C wide-line separation (WISE) and ⁷Li static line NMR width measurements divulge that the mobility of the ⁷Li cations is strongly related to a dynamic environment created by the polymer motion in the amorphous phase. The combined results of conductivity and ⁷Li pulse-gradient spin-echo (PGSE) NMR self-diffusion coefficient measurements reveal that the conductivity enhancement at low salt concentrations is mainly caused by the high mobility of the lithium cations.     

The effects of LiBOB additive for stable SEI formation of PP13TFSI-organic mixed electrolyte in lithium ion batteries

A safe electrolyte system is prepared from N-methyl-N-propylpiperidinium bis (trifluoromethanesulfonyl) imide (PP13TFSI), organic electrolyte (1 mol L⁻¹ LiPF₆/EC-DEC) and lithium bis (oxalato) borate (LiBOB). The additive of LiBOB enhances the stability of interface between electrolyte and anode. The LiBOB-containing mixed electrolytes show non-flammability and good compatibility with active materials. The performance of anode for lithium ion battery is successfully improved by LiBOB-containing mixed electrolytes, which shows 200 mA h g⁻¹ reversible capacities at 0.3 C rate. The ionic conductivity and the lithium ion transference number in LiBOB-containing mixed electrolytes system also suits to application for lithium ion battery.     

Association properties of a high molecular weight poly(propylene oxide–b–ethylene oxide) diblock copolymer in aqueous solution

Summary Summary A high molecular weight poly(propylene oxide–b–ethylene oxide) diblock copolymer was prepared via sequential anionic suspension polymerization using a calcium amidealkoxide initiating system. ¹H nuclear magnetic resonance, viscometry and static and dynamic light scattering have been used to characterize the copolymer and to examine its self–assembly in aqueous solution. The copolymer was found to self–associate in a narrow concentration range above a certain critical aggregation concentration. The weight–average molecular weight, the radii of gyration, the second virial coefficients, the diffusion coefficients, and the hydrodynamic radii of the particles in both unimer and aggregate regions were determined. Aggregates of low aggregation number (2–3) were formed. Dynamic light scattering measurements performed in a wide concentration range revealed an enhanced aggregate stability towards dissociation upon dilution.     

Synthesis of sulfonated poly(styrene-co-methyl methacrylate) by semicontinuous heterophase polymerization for filtration membranes

In this study, styrene (St) and methyl methacrylate (MMA) were copolymerized in semicontinuous heterophase using Hitenol-BC10 (HBC10) as polymerizable surfactant and ammonium persulfate as initiator to obtain copolymers of poly(St-co-MMA). The effects of St/MMA weight ratio and surfactant concentration on kinetics, and colloidal properties of latexes were studied. Copolymers and latexes were characterized by scanning electron microscopy, thermogravimetric analysis (TGA), gel permeation chromatography (GPC), Fourier transform infrared (FTIR) spectroscopy, and X-ray diffraction analysis. Fast reaction rates under monomer starved conditions and high conversions (>85%) were observed in all cases, with a weight-average molecular weight in the range of 2.10 × 10⁶ to 0.96 × 10⁶ g mol⁻¹, decreasing with the HBC10 concentration due to an effect of chain transference to surfactant. Stable latexes with spherical particles with average diameter in the interval of 65–41 nm and Z-potential in the interval of −68.24 to −38.44 mV were obtained. Copolymers were sulfonated using acetyl sulfate as sulfonating agents and subsequently used for filtration membrane fabrication through the phase inversion method. Membranes were tested in simulated seawater filtration (3.5% NaCl) under constant pressure. At a pressure of 20 psia, permeated flux (J) of pure water and salt rejection (R) varied from 13.8 to 20.5 L m⁻² h⁻¹ and 37.8%–50.7%, respectively. It was concluded that membrane's performance is dependent on copolymer composition, the crystallinity of copolymers, and the ionic exchange capacity of membranes, being the best membrane composed of 90/10 of St-to-MMA weight ratio and using a monomer-to-surfactant weight ratio of 29.9.     

Measurement of transference numbers for lithium ion electrolytes via four different methods, a comparative study

We report here on comparative measurements of cationic transference numbers of some lithium battery related electrolytes including lithium tetrafluoroborate in propylene carbonate, lithium hexafluorophosphate in blends of ethylene carbonate/diethyl carbonate and ethylene carbonate/propylene carbonate/dimethyl carbonate, as well as lithium difluoromono (oxalate) borate in an ethylene carbonate/diethyl carbonate blend via four different methods. Whereas three electrochemical methods yield transference numbers decreasing with concentration in accordance with electrostatic theories, valid for low to intermediate concentrations of the electrolyte, nuclear magnetic resonance spectroscopy measurements show increasing transference numbers with increasing concentration. The discrepancy is attributed to effects of ion–ion and ion–solvent interaction.     

Enhanced ion conductivity of poly(ethylene oxide)-based single ion conductors with lithium 1,2,3-triazolate end groups

Poly(ethylene oxide) (PEO)-based single ion conductors (SICs) are of great interest for applications in modern lithium ion batteries. They have several advantages over other common electrolytes such as high cation transference numbers, low toxicity, and nonflammability, but their major disadvantage is the low ion conductivity. Here, linear PEO-based SICs with lithium 1,2,3-triazolate (TrLi) end groups are synthesized and studied in terms of crystallinity by differential scanning calorimetry, and with respect to ion conductivity by impedance spectroscopy. Introduction of TrLi end groups to PEO chains reduces its crystallinity and melting temperature as well as an enhancement of the ion conductivity up to 8.0·10⁻⁶ S cm⁻¹ at 70°C is observed. The increased ion conductivity is a direct result of the Tr rings, which can actively contribute to the conduction mechanism. In comparison with conductivities of other PEO-based SICs reached so far (σ₀ ≤ 10⁻⁶ S cm⁻¹), the results of this study show that the introduction of TrLi end groups is a new approach to enhance the Li⁺-ion conductivity of PEO-based SICs that have also a good electrochemical stability versus lithium electrodes as revealed by linear sweep voltammetry. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 46949.     

Synthesis of graft copolymer polyethylene‐ graft‐poly(ethylene oxide) by a new anionic graft‐from polymerization

A series of amphiphilic graft copolymers, PE‐graft‐PEO, containing hydrophobic polyethylene (PE) as the backbone and hydrophilic poly(ethylene oxide) (PEO) as the side‐chain, have been synthesized by a novel route. The graft structure and the molecular weight, as well as the molecular weight distribution of the graft copolymer can easily be controlled. The molecular weight of the side‐chain PEO is proportional to the reaction time and the monomer concentration, which indicates the ‘living’ character of the anionic polymerization of ethylene oxide. The produced copolymers PE‐graft‐PEO were characterized by ¹H NMR and DSC measurements. Copyright © 2004 Society of Chemical Industry     

Cationic conduction in oligoether salt–comblike polyether complex

Polymeric solid electrolytes, with excellent cationic conductivity, were prepared from the complexation of lithium methoxyoligo(oxyethylene) sulfate and lithium methoxyoligo(oxyethylene) sulfonate with poly[methoxyoligo(oxyethylene)methacrylate-co-acrylamide]. The electrolytes exhibit low glass transition temperature and have almost no crystal. Their ionic conductivities at 25°C are over 10^?5 S/cm. The carrier number in the complex decreases while ionic mobility increases considerably with increasing considerably with increasing temperature. The polarization reversing method confirms that the cationic transference numbers are all over 0.9. The electrolytes have single ion conduction characteristics in DC polarization. © 1995 John Wiley & Sons, Inc.     

Porous biodegradable polyesters. I. Preparation of porous poly(L‐lactide) films by extraction of poly(ethylene oxide) from their blends

Porous poly(L ‐lactide) (PLLA) films were prepared by water extraction of poly(ethylene oxide) (PEO) from solution‐cast PLLA and PEO blend films. The dependence of blend ratio and molecular weight of PEO on the porosity and pore size of films was investigated by gravimetry and scanning electron microscopy. The film porosity and extracted weight ratio were in good agreement with the expected for porous films prepared using PEO of low molecular weight (M_w = 1 × 10³), but shifted to lower values than expected when high molecular weight PEO (M_w = 1 × 10⁵) was utilized. The maximum pore size was larger for porous films prepared from PEO having higher molecular weight, when compared at the same blending ratio of PLLA and PEO before water extraction. Differential scanning calorimetry of as‐cast PLLA and PEO blend films revealed that PLLA and PEO were phase‐separated at least after solvent evaporation. On the other hand, comparison of blend films before and after extraction suggested that a small amount of PEO was trapped in the amorphous region between PLLA crystallites even after water extraction and hindered PLLA crystallization during solvent evaporation. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 629–637, 2000     

An easy one-step electrosynthesis of graphene/polyaniline composites and electrochemical capacitor

An easy electrochemical technique is proposed to prepare electrochemically reduced graphene oxide (ERGO)/polyaniline (PANI) composites in a single step. The technique uses a two-electrode cell in which a separator soaked with an acid solution is sandwiched between graphene oxide (GO)/aniline films deposited on conductive substrates and an alternating voltage was applied to the electrodes. Successful preparations of ERGO/PANI composites were evidenced by characterizations due to UV–vis-NIR, FT-IR, XPS, XRD, and SEM measurements with free-standing films of ERGO/PANI obtained easily by disassembling the two-electrode cells. The ERGO/PANI films exhibited a high mechanical stability, flexibility, and conductivity (68 S cm⁻¹ for the composite film containing 80% ERGO) with nanostructured PANI particles (smaller than 20 nm) embedded homogeneously between the ERGO layers. The two-electrode cells acted as electrochemical capacitors (ECs) after a sufficient voltage cycling and exhibited relatively large specific capacitances (195–243 F g⁻¹ at a scan rate of 100 mV s⁻¹) with an excellent cycle life (retention of 83% capacitance after 20,000 charge–discharge cycles). Influences of the GO/aniline ratio, the sort of electrolytes, and the weight of the composite on the energy storage characteristics of ECs comprising the ERGO/PANI composites were also studied.     

Ionic conductivity and lithium electrode stability in Hydrin: LiBF4 elastomers

Three commercial elastomers, Hydrin C, Hydrin H and Hydrin T, which contain ethylene oxide and epichlorohydrin repeat units, have been investigated as polymer electrolytes in contact with lithium electrode. The influence of polyethylene glycol and fine particles of zeolite on ionic conductivity of Hydrin-LiBF₄ electrolytes and the exchange current density of the lithium electrode reaction has been studied by using impedance spectroscopy and cyclic voltammetry. The specific conductivity of the elastomeric electrolyte is about 10^–5 S cm^–1 at room temperature when polyethylene glycol is present. But the mechanical stability of the film is less. The addition of zeolite particles to the elastomers also improves the specific conductivity. When present in low concentrations, the zeolite particles show catalytic effect on the electrochemical reaction at lithium electrode at ambient temperature. The lithium electrode reaction is reversible and the electrolyte possesses good electrochemical stability.     

Effect of electrolyte on interfacial dilational properties of chemical flooding systems by relaxation measurements

In the present work, the influences of different types of electrolytes on interfacial dilational properties of anionic surfactant sodium 4,5-diheptyl-2-propylbenzene sulfonate 377 and asymmetrical anionic Gemini surfactant C₁₂COONa-p-C₉SO₃Na in the absence or presence of 1500 ppm partly hydrolyzed polyacrylamide were studied at decane–water interface, respectively, by means of interfacial tension relaxation measurements. The decay curves of interfacial tension were fitted by the summation of a number of exponential functions. The dilational elasticity (?_r) and dilational viscosity component (?_i) were calculated by Fourier transform and displayed as Cole–Cole plots (plotting ?_i or ?_i/?₀ as a function of ?_r or ?_r/?₀ respectively). The experimental results show that only single reorientation process dominates the interfacial properties in the presence of any electrolyte for 1 × 10⁻⁶ mol L⁻¹ 377 solution, resulting form the more compacted film by electrostatic screening. On the other hand, the contribution of reorientation process at higher frequency decrease after the addition of NaCl and there exists no pure reorientation process in the presence of CaCl₂ or MgCl₂ for Gemini surfactant because of the slight increase of interfacial concentration due to larger molecular size and strong steric hindrance between alkyl chains. The addition of polymer can significantly modify the dilational properties of adsorbed surfactant layer due to the formation of mixed adsorption film through hydrophobic interaction between polymer chain and alkyl chain of surfactant molecule. The normalized Cole–Cole plots of surfactant-polymer films with different types of electrolytes show the similar characteristic in general and no pure reorientation process can be observed in any case.