Zinc ion conducting blended polymer electrolytes based on room temperature ionic liquid and ceramic filler

Zinc ion conducting nanocomposite gel polymer electrolytes (NCGPEs) comprising of poly(vinyl chloride) (PVC)/poly(ethyl methacrylate) (PEMA) blend, zinc triflate [Zn(OTf)₂] salt, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMIMTFSI) ionic liquid (IL) and fumed silica (SiO₂) viz. [PVC/PEMA–Zn(OTf)₂–EMIMTFSI–SiO₂] exhibited the highest ionic conductivity value of 6.71 × 10⁻⁴ Scm⁻¹ at room temperature. The ion–filler–polymer interactions and probable conformational changes observed in the structure of the gel composites due to the entrapment of IL and dispersion of nano-sized SiO₂ were confirmed from X-ray diffraction (XRD) and Attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy. Scanning electron microscopic (SEM) images of NCGPEs demonstrated uniform surface with abundant interconnected micropores. The cationic transport number of NCGPE samples has been found to be appreciably enhanced up to a maximum of 0.69 thus demonstrating a considerable improvement in Zn²⁺ ion conductivity. The NCGPE film possesses an electrochemical stability window up to 5.07 V (vs. Zn/Zn²⁺) and ensures feasible zinc stripping/plating in the redox process. The addition of SiO₂ into the gel polymer electrolyte system has effectively reduced the glass-transition temperature (T_g) of the NCGPE films and also accomplished improved thermal stability up to approximately 180 °C which were ascertained from Differential scanning calorimetry (DSC) and Thermogravimetric (TG) results. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47654.     

Ion migration in liquid polymer electrolytes

Solutions of alkali metal thiocyanates in liquid copolymers of ethylene oxide and propylene oxide provide a convenient medium for measuring conductivities, viscosities and transport numbers in polymer electrolytes by classical methods. The high value of the anion transport number (typically ca. 0.95) is noteworthy. A model, which emphasises the importance of intramolecular solvation of cations, the effects of ion pairing and redissociation, and the crosslinking action of anions at high salt concentrations, accounts satisfactorily for the properties of these liquid systems.     

Ion transport phenomena in polymeric electrolytes

The aim of the present work is to generalize an ion transport phenomena observed in composite polymeric electrolytes using the previously developed models as well as design a new approach which would be helpful in describing changes in conductivity and lithium ion transference numbers occurring upon addition of fillers to polymeric electrolytes. The concept is based on the observation of changes in ionic associations in the polymeric electrolytes studied in a wide salt concentration range. The idea is illustrated by the results coming from a variety of electrochemical and structural data obtained for composite electrolytes containing specially designed inorganic and organic fillers.     

Tailor-made fumed silica-based nano-composite polymer electrolytes consisting of BmImTFSI ionic liquid

In this work, nano-sized fumed silica (SiO₂) was embedded in poly(methyl methacrylate) (PMMA)?Cpoly(vinyl chloride) (PVC) blend with 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl imide) (BmImTFSI) as ionic liquid. These composite polymer electrolytes (CPEs) were prepared by solution casting technique. The samples followed Arrhenius behavior in the temperature-dependence of ionic conductivity and further proved the ionic hopping mechanism in the polymer electrolyte. It is suggested the formation of three-dimensional polymer network among the aggregates weakens the interaction of polar group of the polymer backbone and initiates the ionic decoupling process. The mobile ions from adjacent sites would occupy this vacant site and reform the interactive bond with the polymer backbone whereby the ionic hopping mechanism is generated. The activation energy (E _a) is further determined. The higher the ionic conductivity, the lower the activation energy. The maximum ionic conductivity of (8.26?±?0.02) mScm^?1 was achieved at 80?°C upon inclusion of 8 wt% of SiO₂. X-ray diffraction (XRD) analysis revealed the higher amorphous region with increasing SiO₂ mass loadings. The coherence length is further determined by using Debye?CScherrer equation. Higher amorphous region in the polymer matrix is conferred by showing the lower coherent length. Scanning electron microscopy (SEM) was applied to examine the morphology of polymer electrolytes. Based on the differential scanning calorimetry (DSC) study, glass transition temperature (T _g) and melting temperature (T _m) were decreased. Highly flexible polymer chain is produced when the T _g was lowered down. On the other hand, thermal stability of polymer electrolytes was increased by SiO₂ dispersion, as depicted in thermogravimetric analysis (TGA).     

Ion, solvent and polymer dynamics in polyaniline conducting polymer films

We describe the application of a new model for the visualization of mobile species (ion and solvent) transfers accompanying redox switching of electroactive films. The system studied was polyaniline, for which the mobile species population changes were determined from redox-driven film mass changes using a thickness shear mode acoustic wave resonator. Acoustic admittance data were used to establish conditions under which the resonator frequency response could be interpreted gravimetrically. Charge and frequency changes accompanying the first redox transition of polyaniline films exposed to aqueous perchloric acid were then used to determine the film's ion and solvent populations. The data are best described by a mechanism in which the early stages of film oxidation are associated with proton transfer (exit) and the latter stages with perchlorate transfer (entry) to satisfy electroneutrality; solvent enters throughout film oxidation and exits throughout film reduction. The alternative of a single ion satisfying electroneutrality throughout would require the rather less likely situation of a non-monotonic solvent flux. Application of the model's diagnostic criteria indicates that the film solvent population is in equilibrium on the timescale of slow scan voltammetry, but shows thermodynamic non-idealities. Hysteresis in the film ion population signals failure of the redox state to maintain equilibrium with the applied potential.     

Electroplasticity memory devices using conducting polymers and solid polymer electrolytes

Erasable memory devices are fabricated by the combination of a conducting polymer and solid polymer electrolyte. The former is used as a memory channel and the latter as an electrolyte medium. The channel conductivity can be controlled over 3-4 orders of magnitude by electrochemical doping through a writing electrode. The response time, depending on the writing voltage, is several seconds. The characteristics of the memory device are discussed.     

Characterizations of proton conducting polymer electrolytes for electrochemical capacitors

Solid polymer electrolytes containing phosphotungstic acid (PWA) and/or silicotungstic acid (SiWA) in polyvinyl alcohol (PVA) were investigated for their proton conductivities. Enhanced conductivity was obtained when mixing PWA and SiWA at equal ratio. This polymer electrolyte was found viable for electrochemical capacitors. Thermal and structural analyses were conducted with DSC, XRD, and FTIR. The polymer electrolyte exhibited a different structure and different thermal properties from its respective components. The polymer electrolyte retained its original Keggin structure but contained crystallized protonated water in the form of H₅O₂⁺. The protonated water may contribute to the proton conductivity of the polymer electrolyte.     

Electrospun PVdF-based fibrous polymer electrolytes for lithium ion polymer batteries

This paper discusses the preparation of microporous fibrous membranes from PVdF solutions with different polymer contents, using the electrospinning technique. Electrospun PVdF-based fibrous membranes with average fiber diameters (AFD's) of 0.45-1.38 μm have an apparent porosity and a mean pore size (MPS) of 80-89% and 1.1-4.3 μm, respectively. They exhibited a high uptake of the electrolyte solution (320-350%) and a high ionic conductivity of above 1 × 10⁻³ s/cm at room temperature. Their ionic conductivity increased with the decrease in the AFD of the fibrous membrane due to its high electrolyte uptake. The interaction between the electrolyte molecules and the PVdF with a high crystalline content may have had a minor effect on the lithium ion transfer in the fibrous polymer electrolyte, unlike in a nanoporous gel polymer electrolyte. The fibrous polymer electrolyte that contained a 1 M LiPF₆-EC/DMC/DEC (1/1/1 by weight) solution showed a high electrochemical stability of above 5.0 V, which increased with the decrease in the AFD The interfacial resistance (R_i) between the polymer electrolyte and the lithium electrode slightly increased with the storage time, compared with the higher increase in the interfacial resistance of other gel polymer electrolytes. The prototype cell (MCMB/PVdF-based fibrous electrolyte/LiCoO₂) showed a very stable charge-discharge behavior with a slight capacity loss under constant current and voltage conditions at the C/2-rate of 20 and 60 °C.     

Structural and ion transport properties of sodium ion conducting Na2MTeO6 (M= MgNi and MgZn) solid electrolytes

Solid-state electrolytes Na₂MTeO₆ (M = MgNi and MgZn) were prepared via a conventional solid-state reaction method. Structural properties of the samples were investigated by using powder X-ray diffraction (XRD), Raman, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy (XPS) techniques. XPS and XRD studies indicate the phase pure hexagonal layered P2-type structure of samples. Raman and FTIR spectroscopy reveal the possible bending and stretching vibration modes for Te–O and other metal oxides. The ion transport properties of the solid electrolytes were investigated by using AC impedance spectroscopy. The electrical properties were examined by means of classical brick layer model. The specific grain conductivity (σ_g) is found to be 2.13 × 10⁻⁵ S cm⁻¹ and 0.90 × 10⁻⁵ S cm⁻¹ at 20 °C for Na₂MgNiTeO₆ and Na₂MgZnTeO₆ electrolytes, respectively. The activation energy of σ_g for Na₂MgNiTeO₆ and Na₂MgZnTeO₆ is found to be 0.59 eV and 0.36 eV respectively for the temperature below 30 °C. Summerfield AC conductivity scaling analysis of samples is performed. These electrolytes could be potential candidates in solid-state Na⁺ battery applications.     

Sonochemical synthesis and characterization of amine‐modified graphene/conducting polymer nanocomposites

The objective of this work is to modify graphene and study the effect of modification of graphene in thermal and electrical properties of graphene/polypyrrole and graphene/polyaniline nanocomposites. The amine functionalization of graphene was confirmed by Fourier transform infrared spectroscopy and X‐ray photoelectron spectroscopy. The nanocomposites were prepared by insitu oxidative polymerization method using ammonium persulfate as oxidant. Field emission scanning electron microscopy and high‐resolution transmission electron microscopy were used to study the morphology of the nanocomposites which indicates toward the better dispersion of modified graphene within the polymer matrices as compared to unmodified composites. The modification of graphene played an important role in the noticeable improvements in electrical conductivity of the prepared composites. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Studies of a novel conducting polymer by cyclic and square wave voltammetries: Its synthesis and characterization

A novel conducting polymer of polynaphthidine, poly(NAP), was synthesized electrochemically by direct anodic oxidation of naphthidine in aqueous media. The yield of the electropolymerization reaction depends on the temperature and pH of the solution. It was possible to differentiate two working regions: I (for pH < 0.5 and all temperatures) where the film yield tends to zero and II (for approximately 2.0 < pH < 2.8 and temperatures >15 °C) where the film production is maximum. Therefore, the naphthidine electrooxidation mechanism was studied under experimental conditions of region I by cyclic (CV) and square wave voltammetries (SWV) as well as by controlled potential electrolysis.The experimental conditions of region II were chosen to obtain the poly(NAP). The electrochemical response of the film was investigated in pH 1 HClO₄ + 0.1 M NaClO₄ electrolyte solution by CV and SWV. A plot of I_p,n/fvs. f from SW voltammograms showed the so-called “quasi-reversible maximum”. Formal potential, formal rate constant and anodic transfer coefficient for the surface redox process were also evaluated from the SWV.The poly(NAP) is insoluble in common organic solvents and shows electrochromic behaviour. Its probable structure was determined by FTIR spectroscopy.     

A conducting composite of polythiophene: synthesis and characterization

Conducting polymer composites of polythiophene, using a polyamide as the insulating matrix, were prepared via electrochemical methods. The characterization of the composite was done by scanning electron microscopy, differential scanning calorimetry, thermogravimetric analysis, Fourier transform infrared and pyrolysis studies. The conductivities were measured by a four-probe technique. The cited methods revealed that the composites have properties different from those of simple mechanical mixtures of the two polymers.     

Ion and water transport characteristics of Nafion membranes as electrolytes

Transport characteristics of Nafion membranes, that have been published earlier, are re-evaluated. It is found that the specific conductivity of the membranes is not only determined by the mobility of the ions, but largely also by the interaction of ions with water and with microscopic membrane channel structures. Similarly, the water transference coefficient, defined as the number of moles of water transported per Faraday through the membrane, is governed by two effects: an electrostatic effect between ion and water dipoles, and an effect due to the size of the cation. Contributions to electro-osmotic water transfer are water of hydration to cations and hydrodynamically pushed water molecules. The size of the ion compared to the channel diameter, has a major impact on the electric conductivity, but also on water transport. It is shown that hydrophilic cations can promote an enlarged hydrophilic domain in the membrane, that is accompanied by a lower membrane resistance. Criteria for designing high performance ion conducting membranes are given based on this basis.     

Lithium sulfonate promoted compatibilization in single ion conducting solid polymer electrolytes based on lithium salt of sulfonated polysulfone and polyether epoxy

Polymeric lithium salts of sulfonated polysulfone (SPSU(X)Li) were synthesized via post sulfonation route followed by ion exchange. A novel single ion conducting solid polymer electrolyte (SPE) was prepared by curing poly(ethylene glycol)diglycidyl ether (PEGDGE) with 4,4′ diaminodiphenyl sulfone (DDS) in SPSU(X)Li matrix. The ionic conductivity, thermal stability and tensile properties were investigated as a function of degree of sulfonation and PEGDGE concentration. The introduction of lithium sulfonate groups in polysulfone promoted compatibility of SPSU(X)Li and PEGDGE in SPE. AFM analysis demonstrated heterogeneous phase morphology and reduction in size of dispersed PEGDGE phase with increasing degree of sulfonation. The interactions between lithium sulfonate and polyether epoxy improved thermal stability of the epoxy network. The enhanced compatibility also caused improvement in elongation at break compared to neat SPSU(X)Li. The higher Li⁺ ion concentration and the segmental mobility of the polymer chains above T_g contributed to the high ionic conductivity at high temperature in the single ion conducting SPE.     

Processing and characterization of a biaxially oriented conducting polymer

Two methods have been developed for the preparation of biaxially oriented poly(phenylene vinylene) from its poly(sulfonium salt) precursor. A two-stage stretching process permits non-equibiaxial stretching over a wide range of deformation ratios and a bubble expansion technique allows equibiaxial planar extension. The resulting films were examined using X-ray diffraction prior to chemical doping with SbF₅ vapor. Biaxial orientation was shown to exert considerable influence over the attainable electrical conductivity.     

Lithium ion conducting polymeric electrolytes based on poly(ethylene adipate)

We report the preparation and properties of polymeric lithium ion conducting films based on poly(ethylene adipate) with lithium trifluoromethanesulfonate and blends of poly(ethylene adipate) and poly(vinyl acetate) with lithium triflouromethanesulfonate.The conductivity/temperature behaviour of these films was found to be very similar to those based on poly(ethylene oxide), with Arrhenius behaviour above the crystalline melting point and slight hysteresis below this temperature.     

Electrochemical polymerization and characterization of a functional dicarbazole conducting polymer

The electropolymerization of the unique dicarbazole monomer, 2,6-bis-carbazole-9-yl-hexanoic acid pentafluorophenyl ester, is reported. This chiral monomer possesses two carbazole units and a chiral grafting center, activated ester for covalent amine-coupling. Contrary to monocarbazole monomers unable of internal cross-linking, its specifically designed dicarbazole skeleton allowed us to obtain highly reticulated polydicarbazole films functionalized for probe coupling. Full analysis of its electrochemical polymerization revealed different oxidation potentials for the two structurally different carbazole units. The electrochemical activity of the polydicarbazole-coated electrode has been characterized in different redox electrolytes. Contacted by a model protein (BSA), this film has been easily passivated at the Rubpy₃(PF₆) electrochemical window.     

Design and synthesis of conducting secondary crosslinked interpenetrating polymer network

A new conducting composite of a secondary crosslinked interpenetrating polymer network (IPN) was first designed and synthesized by chemically incorporating a rigid conducting polymer within the flexible crosslinked network and forming the link between them. The new conducting composite produced with a low content of polypyrrole exhibited unusually good conductivity, processability, and mechanical properties, and the conductivity was not influenced by the formation of an IPN. © 1997 John Wiley & Sons, Inc.