Conductivity behaviour of proton conducting polymer gel electrolytes with PVdF-HFP

Electrical conductivity of polymer gel electrolytes containing different hydroxy substituted benzoic acids and polyvinylidenefluoride-hexafluoropropylene (PVdF-HFP) has been studied. The conductivity of solution and gel electrolytes shows ortho effect and has been found to depend upon the acidity constant of the acid used and varies as σ (ortho-) > σ (meta-) > σ (para-). The addition of PVdF-HFP to solution electrolytes results in an increase in conductivity and the conductivity of gel electrolytes has been found to be higher than that of the corresponding liquid electrolytes for all the three acids studied i.e. σ (gel) >σ (liquid). The increase in conductivity with polymer addition has also been found to depend upon the acid concentration.     

Quantum chemical modeling of the degradation of the polymer matrix and solvent molecules in nanocomposite polymer gel electrolytes

Quantum chemical calculations of molecular structures and magnetic shielding constants for H and C nuclei were performed by the density functional method. The structures of the polyester diacrylate degradation products formed under sonication in the presence of TiO₂ or Li₂TiO₃ nanoparticles in the electrolyte polyester diacrylate—LiClO₄—ethylene carbonate—nanopowder were proposed based on agreement of the goodness-of-fit with the experimental NMR spectra of the polymer electrolytes. The surface centers on TiO₂ and Li₂TiO₃ under the ultrasonic energy absorption conditions were concluded to catalyze the unexpected metathesis of σ-C—H bonds in the α-positions to the carbonyl group.     

Compositional effect of PVdF-PEMA blend gel polymer electrolytes for lithium polymer batteries

Owing to their improved mechanical properties and good polymer miscibility, the blend gel polymer electrolytes of poly (vinylidene fluoride) (PVdF)-poly(ethyl methacrylate) (PEMA) have been prepared using solvent casting technique and characterized for their electrochemical performances. The electrolyte shows a maximum ionic conductivity of 1.5 × 10⁻⁴ S cm⁻¹ at 301 K for the 90:10 blend ratio of PVdF:PEMA system with good transport property. The ionic conductivity is enhanced, in accompany with improved microstructural homogeneity, at low PEMA contents, while the decreased conductivity at high contents has been attributed to increasing crystalline PEMA domains. With the optimum PVdF:PEMA ratio, the complex system was found to facile reasonable ionic transference number and exhibit superior interfacial stability with Li electrode.     

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.     

Polyethylene oxide-based nanocomposite polymer electrolytes for redox capacitors

In this work, the use of a polyethylene oxide-based nanocomposite polymer electrolyte (NCPE) in a redox capacitor with polypyrrole electrodes has been studied. To the best of our knowledge, not much work has been reported in the literature on redox capacitors fabricated using NCPEs. The composition of the polyethylene oxide (PEO)-based NCPE was fine tuned to obtain films with the highest ionic conductivity. They were mechanically stable to handle for any purpose without damaging the film. The optimized composition was {[(10PEO:NaClO₄) molar ratio]: 75 wt.% propylene carbonate (PC)}: 5 wt.% TiO₂. This electrolyte film showed an ambient temperature ionic conductivity of 5.42 × 10^?3 S cm^?1. It was employed in a redox capacitor with polypyrrole electrodes polymerized in the presence of sodium perchlorate in non-aqueous medium. Performance of the redox capacitors were observed using cycling voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge discharge test. It was possible to observe a satisfactory capacitive behavior in the range 58–83 F/g. Further, the redox capacitors had the ability to retain for continuous charge discharge processes.     

Ionic liquid-based sodium ion-conducting composite gel polymer electrolytes: effect of active and passive fillers

Journal of Solid State Electrochemistry - We report the studies on composite gel polymer electrolytes (GPEs) comprising 0.5 M solution of sodium trifluoromethane sulfonate (Na-triflate or...     

Conductivity studies of polymer electrolytes based on aliphatic polyesters

A series of aliphatic polyesters of sebacoyl chloride and poly(ethylene glycol) containing a different number of ethylene oxide groups was synthesized and characterized. These polyesters were complexed with lithium perchlorate to obtain a new class of polymer electrolyte. The relationships between the structure and properties of these polymer electrolytes were investigated. The main factor that affects the ionic conductivity in these systems was found to be the solvating capacity of the polyester for the lithium salt. These polymer electrolytes showed ionic conductivities up to 10^?5 ? 10^?4 S/cm at 25°C. The mechanical strength was improved by cross-linking, and the cross-linked polyester complexed with a LiCIO₄ salt showed an ionic conductivity of 2 × 10^?5 S/cm at room temperature. ⁷Li NMR spin-spin relaxation and dielectric relaxation studies were also carried out to investigate the local environments and dynamics of ions in the polymer electrolytes. © 1995 John Wiley & Sons, Inc.     

Polyacrylamide-methanesulfonic acid gel polymer electrolytes for tin-air battery

The present work describes the synthesis and characterization of gel polymer electrolytes containing methanesulfonic acid (MSA) with Polyacrylamide (PAAm). The PAAm–MSA gel electrolytes were prepared with different concentrations of MSA. Addition of 0.5 M of MSA into the electrolyte increased the ionic conductivity of PAAm from 1.35 × 10^?3 to 1.56 × 10^?2 S cm^?1. The maximum ionic conductivity of 7.0 × 10^?1 S cm^?1 was obtained with 3 M MSA at room temperature. The chemical interaction between PAAm and MSA was studied by Fourier transformed infra-red. The performance as a polymer electrolyte was evaluated from the cell discharge and open circuit potential measurements of a tin-air cell. The tin-air cell supported relatively high current, up to 12 mA cm^?2 with a maximum power density of 5 mW cm^?2. The open-circuit potential of the cell was 1.27 V for 24 h.     

Review on gel polymer electrolytes for lithium batteries

This paper reviews the state-of-art of polymer electrolytes in view of their electrochemical and physical properties for the applications in lithium batteries. This review mainly encompasses on five polymer hosts namely poly(ethylene oxide) (PEO), poly(acrylonitrile) (PAN), poly(methyl methacrylate) (PMMA), poly(vinylidene fluoride) (PVdF) and poly(vinylidene fluoride-hexafluoro propylene) (PVdF-HFP) as electrolytes. Also the ionic conductivity, morphology, porosity and cycling behavior of PVdF-HFP membranes prepared by phase inversion technique with different non-solvents have been presented. The cycling behavior of LiMn₂O₄/polymer electrolyte (PE)/Li cells is also described.     

Research progress on gel polymer electrolytes for lithium-sulfur batteries

Lithium-sulfur(Li-S)batteries have become a promising candidate for advanced energy storage system owing to low cost and high theoretical specific energy.In the last decade,in pursuit of Li-S batteries with enhanced safety and energy density,the investigation on the electrolytes has leaped form liquid organic electrolytes to solid polymer ones.However,such solid-state Li-S battery system is greatly limited by unfavorable ionic conductivity,poor interfacial contact and narrow electrochemical windows on account of the absence of any liquid components.To address these issues,gel polymer electrolytes(GPEs),the incorporation of liquid electrolytes into solid polymer matrixes,have been newly developed.Although the excellent ionic transport and low interfacial resistance provided by GPEs have prompted numerous researchers to make certain progress on high-performance Li-S coins,a comprehensive review on GPEs for Li-S batteries remains vacant.Herein,this review focuses on recent development and progress on GPEs in view of their physical and chemical properties for the applications in Li-S batteries.Studies on the components including solid hosts,liquid solutions and fillers of GPEs are systematically summarized with particular emphasis on the relationship between components and performance.Finally,current challenges and directional outlook for fabricating GPEs-based Li-S batteries with outstanding performance are outlined.     

Electrical and electrochemical studies on magnesium ion-based polymer gel electrolytes

The development of polymer gel electrolyte system with high ionic conductivity is the main objective of polymer research. Electrochemical devices based on lithium ion-conducting polymer electrolyte are not safe due to the explosive nature of lithium. An attempt has been made to synthesize magnesium ion-conducting polymeric gel electrolytes, poly (vinylidene fluoride-co-hexafluoropropylene)–propylene carbonate–magnesium perchlorate, PVdF(HFP)-PC–Mg(ClO₄)₂ using standard solution-cast techniques. The maximum room temperature ionic conductivity of the synthesized electrolyte system has been observed to be 5.0 × 10⁻³ S cm⁻¹, which is quite acceptable from a device fabrication point of view. The temperature-dependent conductivity and the dielectric behavior were also analyzed. The pattern of the temperature-dependent conductivity shows the Arrhenius behavior. The dielectric constant ε _r and dielectric loss ε _i increases with temperature in the low-frequency region but almost negligible in the high-frequency region. This behavior can be explained on the basis of electrode polarization effects. The real part M _r and imaginary part M _i versus frequency indicate that the systems are predominantly ionic conductors. Further, the synthesized electrolyte materials have been checked for its suitability in energy storage devices namely redox supercapacitor with conducting polymer polypyrrole as electrode materials, and finally, it was observed that it shows good capacitive behavior in low-frequency region. Preliminary studies show that the overall capacitance of 22 mF cm⁻² which is equivalent to a single electrode specific capacitance of 117 F gm⁻¹ was observed for the above said supercapacitors.     

Conductivity,thermal and morphology studies of PEO based salted polymer electrolytes

Polymer electrolyte has been prepared via solution-casting technique. The polymer electrolytes are formed from polyethylene oxide (PEO) and lithium hexafluorate is used as the doping salt. The conductivity increases from 10⁻⁹ to 10⁻⁴ S cm⁻¹ upon the addition of various concentrations of salt. The results reveal that the conductivity increases with increasing temperature when the salt concentration increases up to 20 wt% The conductivity for 20 wt% of salt remains similar to the conductivity for 15 wt% of salt at 318 K. Differential scanning calorimetry studies show that the melting transition temperature and crystallinity decreases upon the addition of various concentrations of salt. Thermogravimetric analysis (TGA) results indicate that a significant effect on the thermal stability of polyethylene–lithium salt composites. SEM images reveal that the morphology of polymer electrolyte's surface changes when various concentrations of salt are added into the polymer system.     

Internal in situ gel polymer electrolytes for high-performance quasi-solid-state lithium ion batteries

Journal of Solid State Electrochemistry - The performance of solid-state lithium ion battery mainly depends on the performance of the electrolyte and the interface between the electrolyte and the...     

Causes of the double maximum conductivity of nanocomposite polymer electrolytes for lithium power sources

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Novel zinc ion conducting polymer gel electrolytes based on ionic liquids

We report novel zinc ion conducting polymer gel electrolytes (PGEs) based on non-volatile room temperature ionic liquids. The PGEs consist of an ionic liquid, with a zinc salt dissolved in it, blended with a polymer matrix, poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP). The resultant electrolyte membranes are freestanding, translucent, flexible and elastic, with excellent mechanical integrity and strength. They possess exceptional thermal stability, exhibit essentially no weight loss under dynamic vacuum or upon heating to 200 °C, and remain the same gel phase in wide temperature ranges, with ionic conductivities on the order of 10⁻³ S/cm at room temperature, 10⁻⁴ S/cm at −20 °C and 4–5 × 10⁻³ S/cm at 80 °C. Electrochemical tests show that zinc ions are mobile in the membranes and zinc metal is capable of dissolution into and deposition from the membranes. The membranes also exhibit wide electrochemical stability windows. The results of this study demonstrate the promise of developing PGEs based on ionic liquids for potential application in next-generation non-aqueous zinc battery systems.     

Insights on electrochemical properties of gel polymer electrolytes based on methylmethacrylate

This paper explains some properties of gel polymer electrolytes, which are mostly used in lithium ion batteries. An emphasis is laid on the internal structure and its influence on the mobility of ions in the substance. The ions are solvated and located randomly in the liquid base of the gel, and their movement is predominantly determined by the Stokes law for liquid electrolytes. Polymethylmethacrylate gel is used as a model substance here. This report is based on the experience of the authors and their associates.     

Composite gel membranes: a new class of improved polymer electrolytes for lithium batteries

Novel composite, gel-type polymer electrolytes have been prepared by dispersing selected ceramic powders into a matrix formed by a lithium salt solution contained in a poly(acrylonitrile) (PAN) network. The electrochemical characterization demonstrates that these new types of composite gel electrolytes have high ionic conductivity, wide electrochemical stability and, particularly, high chemical integrity (no liquid leakage) even at temperatures above ambient. These unique properties make the composite gel membranes particularly suitable as electrolyte separators in lithium ion polymer batteries.     

Acetone adsorption on hydroxylated silica gel: Correlation of sorption isotherms and IR spectra

The synthesis of MTBE from methanol and isobutene has been carried out over a ZSM-5 based catalyst, in two types of continuous flow catalytic reactors, fixed-bed and fluidized-bed. We have studied the influence of the molar ratio methanol to isobutene, the temperature and the weight hourly spatial velocity (WHSV) on the yield of MTBE.     

Substituent effect on the IR and PMR spectra of diphenylamines

PMR chemical shifts of various m- and p-substituted diphenylamines were correlated with σ-constants. However, the NH stretching frequencies of these amines were not linear with the σ- constants, and the irregularity in the ν_NHvs σ plot was interpreted by taking into accounts the following factors: the changes in hybridization of the imino N atoms, the normal electronic effect of the substituent and the steric effect on the planarity of the amine molecules. Results on the CN stretching absorptions were also presented.