Effect of lithium salt concentration in PVAc/PMMA-based gel polymer electrolytes

Hybrid solid polymer electrolyte films comprising of poly(vinyl acetate) (PVAc), poly(methyl methacrylate) (PMMA), LiClO₄, and propylene carbonate are prepared by solution casting technique by varying the salt concentration. In this study, PVAc/PMMA polymer blend ratio is fixed as 25:75 on the basis of conductivity and mechanical stability of the film. X-ray diffraction, Fourier transform infrared impedance, thermogravimetry/differential thermal analysis and scanning electron microscopy studies are carried out for the polymer electrolytes. The maximum ionic conductivity is found to be 4.511 × 10⁻⁴ S cm⁻¹ at 303 K for the plasticized polymer electrolyte with 8 wt.% of LiClO₄. The ionic conductivity is found to decrease with an increase of LiClO₄ concentration.     

Conductivity and thermal studies of blend polymer electrolytes based on PVAc–PMMA

The polymer electrolytes comprising blend of poly(vinyl acetate) (PVAc) and poly(methylmethacrylate) (PMMA) as a host polymer and LiClO₄ as a dopant are prepared by solution casting technique. The amorphous nature of the polymer–salt complex has been confirmed by XRD analysis. The DSC thermograms show two T_g's for PVAc–PMMA blend. A decrease in T_g with the LiClO₄ content reveals the increase of segmental motion. Conductance spectra results are found to obey the Jonscher's power law and the maximum dc conductivity value is found to be 1.76 × 10^− 3 S cm^− 1 at 303 K for the blend polymer complex with 20 wt.% LiClO₄, which is suitable for the Li rechargeable batteries. The conductivity–temperature plots are found to follow an Arrhenius nature. The dc conductivity is found to increase with increase of salt concentration in the blend polymer complexes.     

Development and characterizations of PVdF-PEMA gel polymer electrolytes

A new class of gel polymer electrolytes comprising the blend of poly(ethyl methacrylate) (PEMA) and poly(vinylidene fluoride), the mixture of ethylene carbonate and propylene carbonate as a plasticizer, and lithium perchlorate (LiClO₄) as a salt was prepared using solvent casting technique. The formation of polymer–salt complexes has been confirmed by XRD analysis. Morphological and thermal studies have been performed using SEM and DMA analyses. A comparative look between PEMA and poly(methyl methacrylate) (PMMA) electrolytes has showed that PEMA electrolytes exhibited better electrochemical performances than PMMA electrolytes, despites its lower conductivity.     

New polymer electrolyte based on (PVA–PAN) blend for Li-ion battery applications

A polymer blend electrolyte based on polyvinyl alcohol (PVA) and polyacrylonitrile (PAN) was prepared by a simple solvent casting technique in different compositions. The ionic conductivity of polymer blend electrolytes was investigated by varying the PAN content in the PVA matrix. The ionic conductivity of polymer blend electrolyte increased with the increase of PAN content. The effect of lithium salt concentrations was also studied for the polymer blend electrolyte of high ionic conductivity system. A maximum ionic conductivity of 3.76×10⁻³ S/cm was obtained in 3 M LiClO₄ electrolyte solution. The effect of ionic conductivity of polymer blend electrolyte was measured by varying the temperature ranging from 298 to 353 K. Linear sweep voltammetry and DC polarization studies were carried out to find out the stability and lithium transference number of the polymer blend electrolyte. Finally, a prototype cell was assembled with graphite as anode, LiMn₂O₄ as cathode, and polymer blend electrolyte as the electrolyte as well as separator, which showed good compatibility and electrochemical stability up to 4.7 V.     

Investigations on PMMA-PVdF polymer blend electrolyte with esters of dibenzoic acids as plasticizers

Plasticizers can be used to change the electrical and mechanical 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 (methyl methacrylate) (PMMA), poly (vinylidene fluriode) (PVdF), Lithium perchlorate (LiClO₄) and dioctyl phthalate (DOP), dibutyl phthalate (DBP), dimethyl phthalate (DMP) or diethyl phthalate (DEP) were studied. The polymer films were characterized by X-ray diffraction, Thermal, Fourier transform infrared and impedance spectroscopic studies. It is found that the addition of DMP as the plasticizer in the PMMA / PVdF-LiClO₄ polymer complex favours an enhancement in ionic conductivity. The temperature dependence of the conductivity of the polymer films seems to obey the VTF relation. The conductivity values are presented and the results are discussed.     

Preparation and characterizations of PVAc/P(VdF-HFP)-based polymer blend electrolytes

A novel group of polymer blend electrolytes based on the mixture of poly(vinyl acetate) (PVAc), poly(vinylidene fluoride-hexafluoropropylene) (PVdF-HFP), and the lithium salt (LiClO₄) are prepared by solvent casting technique. Ionic conductivity of the polymer blend electrolytes has been investigated by varying the PVAc and PVdF-HFP content in the polymer matrix. The maximum ionic conductivity has been obtained as 0.527 × 10⁻⁴ Scm⁻¹ at 303 K for PVAc/PVdF-HFP ((25/75) wt.%)/LiClO₄ (8 wt.%). The complex formations ascertained from XRD and FTIR spectroscopic techniques and the thermal behavior of the prepared samples has been performed by DSC analysis. The surface morphology and the surface roughness are studied using SEM and AFM scanning techniques respectively.     

Characterization of blend polymer PVA-PVP complexed with ammonium thiocyanate

Thin films of blend polymer electrolytes comprising poly(vinyl alcohol) (PVA) and poly(vinyl pyrrolidone) (PVP) complexed with ammonium thiocyanate (NH₄SCN) salt in different compositions have been prepared by solution casting technique using distilled water as solvent. The prepared films have been investigated by different experimental techniques. The complexation of these films has been studied by FTIR spectroscopy. The increase in amorphousness of the films with increase in NH₄SCN content has been confirmed by XRD analysis. The addition of ammonium thiocyanate salt to PVA-PVP polymer blend shows a shift in T_g of the blend. The effect of salt concentration and temperature on the ionic conductivity of the polymer blend films has been analyzed using AC impedance spectroscopy. The maximum conductivity of 6.85 × 10^?4 S cm^?1 at room temperature has been observed for the blend with 50 mol% PVA-50 mol% PVP complexed with 40 mol% NH₄SCN. The activation energy has been found to be minimum (0.24 eV) for this sample. Wagner’s polarization technique shows that the charge transport in these blend films is predominantly due to ions. Using the highest conductivity blend polymer electrolyte, a proton battery has been fabricated and its discharge characteristics have been studied.     

A novel PEO-based blends solid polymer electrolytes doping liquid crystalline ionomers

A novel PEO-based blends solid polymer electrolytes doping liquid crystalline ionomers (LCI), PEO/PMMA/LiClO₄/LCI, and PEO/LiClO₄/LCI were prepared by solution casting technology. Scanning electron microscope (SEM) and energy-dispersive spectroscopy (EDS) analysis proved that LCI uniformly dispersed into the solid electrolytes and restrained phase separation of PEO and PMMA. Differential scanning calorimetry (DSC) results showed that LCI decreases the crystallinity of blends solid polymer electrolytes. Thermogravimetric analysis (TGA) proved LCI not only improved thermal stability of PEO/PMMA/LiClO₄ blends but also prevent PEO/PMMA from phase separation. Infrared spectra results illustrated that there exists interaction among Li⁺ and O, and LCI that promotes the synergistic effects between PEO and PMMA. The EIS result revealed that the conductivity of the electrolytes increases with LiClO₄ concentration in PEO/PMMA blends, but it increases at first and reaches maximum value of 2.53?×?10^?4 S/cm at 1.0 % of LCI. The addition of 1.0 % LCI increases the conductivity of the electrolytes due to that LCl promoting compatibility and interaction of PEO and PMMA. Under the combined action of rigidity induced crystal unit, soft segment and the terminal ionic groups in LCI, PEO/PMMA interfacial interaction are improved, the reduction of crystallinity degree of PEO leads Li⁺ migration more freely.     

Dielectric and conductivity relaxations in PVAc based polymer electrolytes

The polymer electrolytes composed of a blend of poly (vinyl acetate) (PVAc) and poly (methylmethacrylate) (PMMA) as a host polymer and LiClO₄ as a salt are prepared by a solution casting technique. The formation of blend polymer- salt complex has been confirmed by FT-IR spectral studies. The conductivity- temperature plots are found to follow an Arrhenius nature. Arrhenius plot shows the decrease in activation energy with the increase in salt concentration. The dielectric behaviour of the sample is analysed using dielectric permittivity (ε′), dielectric loss (ε″) and electric modulus (M″) of the samples. The impedance cole- cole plot shows the high frequency semi- circle is due to the bulk effect of the material and the depression in the semicircle shows the non-Debye nature of the material. The bulk conductivity is found to vary between 2.5×10⁻⁵ Scm⁻¹ to 1.7×10⁻³ Scm⁻¹ with the increase of salt concentration of blend polymer samples. The migration energy derived from the dissipation factor is almost equal to the activation energy calculated from conductivity. The modulus spectrum of the samples shows the non-Debye behaviour of the polymer electrolyte films. The low frequency dispersion of the dielectric constant implies the space charge effects arising from the electrodes. Paper presented at the 2nd International Conference on Ionic Devices, Anna University, Chennai, India, Nov. 28–30, 2003.     

Electrical conductivity studies on PVA/PVP-KOH alkaline solid polymer blend electrolyte

A series of conducting thin-film solid electrolytes based on poly (vinyl alcohol)/ poly (vinyl pyrrolidone) (PVA/PVP) polymer blend was prepared by the solution casting technique. PVA and PVP were mixed in various weight percent ratios and dissolved in 20 ml of distilled water. The samples were analyzed by using impedance spectroscopy in the frequency range between 100 Hz and 1 MHz. The PVA/PVP system with a composition of 80% PVA and 20 wt.% PVP exhibits the highest conductivity of (2.2±1.4) × 10⁻⁷ Scm⁻¹. The highest conducting PVA/PVP blend was then further studied by adding different amounts of potassium hydroxide (KOH) ionic dopant. Water has been used as solvent to prepare PVA/PVP-KOH based alkaline solid polymer blend electrolyte films. The conductivity was enhanced to (1.5 ± 1.1) × 10⁻⁴ Scm⁻¹ when 40 wt.% KOH was added. Paper presented at the International Conference on Functional Materials and Devices 2005, Kuala Lumpur, Malaysia, June 6 – 8, 2005.     

Ionic conductivity studies in PMMA/PVdF polymer blend electrolyte with lithium salts

Batteries using ionically conducting polymer membranes as electrolytes are very attractive, since the concept of power sources capable of combining a high energy content with plasticity is very appealing for the consumer electronics market and in electric vehicle applications. Blend based polymer electrolytes composed of poly (methylmethacrylate) (PMMA), Poly Vinylidene fluoride (PVdF), Lithium salt (LiX) (X=ClO₄, BF₄ and CF₃SO₃) and Dimethyl Phthalate (DMP) are prepared using solvent casting technique. The films have been characterized using XRD, FTIR, Thermal and SEM studies; the effect of complexing salt and temperature on ionic conductivity is also discussed. The maximum conductivity value obtained for the solid polymer electrolyte film at 303 K is 4.2 × 10⁻³ S/cm.     

Conductivity studies of plasticized proton conducting PVA–PVIM blend doped with NH4BF4

The proton conducting solid-state polymer electrolyte comprising blend of poly(vinyl alcohol) (PVA) and poly(N-vinylimidazole) (PVIM), ammonium tetrafluoroborate (NH₄BF₄) as salt, and polyethylene glycol (PEG) (molecular weight 300 and 600) as plasticizer is prepared at various compositions by solution cast technique. The prepared films are characterized by Fourier transform infrared spectroscopy, differential scanning calorimetry, X-ray diffraction, and scanning electron microscopy analysis. The conductivity–temperature plots are found to follow an Arrhenius nature. The conductivity of solid polymer electrolytes is found to depend on salt and plasticizer content and also on the dielectric constant value and molecular weight of the plasticizer. Maximum ionic conductivity values of 2.20?×?10^?4 and 1.28?×?10^?4?S?cm^?1 at 30 °C are obtained for the system (PVA–PVIM)?+?20 wt.% NH₄BF₄?+?150 wt.% PEG300 and (PVA–PVIM)?+?20 wt.% NH₄BF₄?+?150 wt.% PEG300, respectively. The blended polymer, complexed with salt and plasticizer, is shown to be a predominantly ionic conductor. The proton transport in the system may be expected to follow Grotthuss-type mechanism.     

Preparation and characterization of PVAc–PMMA-based solid polymer blend electrolytes

In the present work, a novel blend polymer electrolyte membrane using poly(vinyl acetate) (PVAc), poly(methyl methacrylate) (PMMA), and lithium per chlorate (LiClO₄) in different compositions has been prepared by the solution-casting technique. Their chemical, structural characters, thermal behavior, surface morphology, and ionic conductivity were studied using Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric/differential thermal analyzer, scanning electron microscopy, and AC impedance analyzer, respectively. A maximum ionic conductivity value of 1.67 × 10⁻⁴ S/cm at 303 K is obtained for PVAc–PMMA–LiClO₄ complexes in the ratio of 25 × 75, keeping LiClO₄ constant as 10 wt.% among all the compositions studied.     

Effects of MnO<Subscript>2</Subscript> nano-particles on the conductivity of PMMA-PEO-LiClO<Subscript>4</Subscript>-EC polymer electrolytes

Li-ion rechargeable batteries based on polymer electrolytes are of great interest for solid state electrochemical devices nowadays. Many studies have been carried out to improve the ionic conductivity of polymer electrolytes, which include polymer blending, incorporating plasticizers and filler additives in the electrolyte systems. This paper describes the effects of incorporating nano-sized MnO₂ filler on the ionic conductivity enhancement of a plasticized polymer blend PMMA–PEO–LiClO₄–EC electrolyte system. The maximum conductivity achieved is within the range of 10⁻³ S cm⁻¹ by optimizing the composition of the polymers, salts, plasticizer, and filler. The temperature dependence of the polymer conductivity obeys the VTF relationship. DSC and XRD studies are carried out to clarify the complex formation between the polymers, salts, and plasticizer.     

Polymer electrolytes based on copolymer of poly(ethylene glycol) dimethacrylate and imidazolium ionic liquid

Polymer electrolytes based on the copolymer of N-vinylimidazolium tetrafluoroborate (VyImBF₄) and poly(ethylene glycol) dimethacrylate (PEGDMA) have been prepared. Ethylene carbonate (EC) and LiClO₄ are added to form gel polymer electrolytes. The chemical structure of the samples and the interactions between the various constituents are studied by FT-IR. TGA results show that these polymer electrolytes have acceptable thermal stability, are stable up to 155 °C. Measurements of conductivity are carried out as a function of temperature, VyImBF₄ content in poly(VyImBF₄-co-PEGDMA), and the concentration of EC and LiClO₄. The conductivity increases with PEGDMA and EC content. The highest conductivity is obtained with a value of 2.90 × 10^? 6 S cm^? 1 at room temperature for VP1/EC(25 wt.%)–LiClO₄ system, corresponding to the LiClO₄ concentration of 0.70 mol kg^? 1 polymer.     

Infrared and conductivity studies on blends of PMMA/PEO based polymer electrolytes

Poly(methylmetacrylate)/poly(ethylene oxide) (PMMA/PEO) based polymer electrolytes were synthesized using the solution cast technique. Four systems of PMMA/PEO blends based polymer electrolytes films were investigated:

1. PMMA/PEO system,
2. PMMA/PEO + ethylene carbonate (EC) system,
3. PMMA/PEO + lithium hexafluorophosphate (LiPF₆) system and
4. PMMA/PEO + EC + LiPF₆ system.

The polymer electrolytes films were characterized by Impedance Spectroscopy and Fourier Transform Infrared Spectroscopy (FTIR). The FTIR spectra show the complexation occurring between the polymers, plasticizer and lithium salt. The FTIR results give further insight in the conductivity enhancement of PMMA/PEO blends based polymer electrolytes.     

Rheological properties and impedance spectroscopy of PMMA-PVdF blend and PMMA gel polymer electrolytes for advanced lithium batteries

In the present study, blend ionic conducting membranes formed by poly(methylmethacrylate (PMMA) / poly(vinilydenefluoride) (PVDF) (blend ratio PMMA/PVdF=80/20), lithium perchlorate (LiClO₄) as a salt and a mixture of ethylene carbonate (EC)-propylene carbonate (PC) as plasticizer are prepared and characterized by impedance spectroscopy and dynamic rheological experiments. We compared the results obtained on the blends with those on PMMA gel-based polymer electrolytes incorporating the same EC/PC mixture of plasticizer and the same quantities of salt. The main focus of this study is to illustrate the rheological data of the gels and blends electrolytes to point up their mechanical stability with the temperature in sight of the technological application. The conductivity values are reported in the 20–100 °C temperature range for different lithium salt contents, while the rheological behaviour has been recorded up to 140 °C. Paper presented at the Patras Conference on Solid State Ionics — Transport Properties, Patras, Greece, Sept. 14 – 18, 2004.     

Characterization of high ionic conducting PVAc–PMMA blend-based polymer electrolyte for electrochemical applications

A solid polymer blend electrolyte is prepared using poly(vinyl acetate) (PVAc) and poly(methyl methacrylate) (PMMA) polymers with different molecular weight percentage (wt%) of ammonium thiocyanate (NH₄SCN) by solution casting technique with tetrahydrofuran (THF) as a solvent. The structural, morphological, vibrational, thermal and electrical properties of the prepared polymer blend electrolytes have been studied. The incorporation of NH₄SCN into the polymeric matrix causes decrease in the degree of crystallinity of the samples. The complex formation between the polymer and salt has been confirmed by FTIR technique. The increase in T _g with increase in salt concentration has been investigated. The maximum conductivity of 3.684?×?10^?3 S cm^?1 has been observed for the composition of 70PVAc/30PMMA/30 wt% of NH₄SCN at 303 K. This value of ionic conductivity is five orders of magnitude greater than that of 70PVAc/30PMMA polymer membrane. Dielectric and transport studies have been done. The highest conducting polymer electrolyte is used to fabricate proton battery with the configuration Zn/ZnSO₄·7H₂O (anode) ||polymer electrolyte||PbO₂/V₂O₅ (cathode). The open circuit voltage of the fabricated battery is 1.83 V, and its performance has been studied.     

High ionic conductive behavior of cyanoethylated polyvinylalcohol- and polyacrylonitrile-based electrolytes

New type polymer electrolyte films based on poly(acrylonitrile), (PAN), and cyanoethylated poly(vinyl alcohol), (CN-PVA), were prepared and their conducting behaviors were investigated. CN-PVA was prepared from poly(vinyl alcohol), (PVA) and acrylonitrile in the presence of sodium hydroxide and quaternary ammonium halide as a phase transfer catalyst. Free standing PAN- and CN-PVA-based electrolyte films were prepared by casting the propylene carbonate (PC) solution containing PAN, CN-PVA and LiClO₄ and removing some amount of PC. Ionic conductivity of the electrolyte film, (PAN)10(CN-PVA) 10(LiClO₄)8(PC)4 composite film was 14.6 mS cm^− 1 at 30 °C and 22.4 mS cm^− 1 at 60 °C. FTIR results for the electrolyte films suggest that the nitrile groups in the CN-PVA matrix mainly interact with the lithium ions in the films and enhance dissolution of the lithium salt in the electrolyte films.     

Magnesium ion conducting polyvinyl alcohol–polyvinyl pyrrolidone-based blend polymer electrolyte

Structural, thermal, electrical and electrochemical behaviour of polymer blend electrolytes comprising polyvinyl alcohol (PVA) and polyvinyl pyrrolidone (PVP) as host polymers and Mg(ClO₄)₂ as dopant salt have been investigated. The changes in the structural properties on the incorporation of dopant in the blends were investigated by XRD and FTIR analyses. Thermal properties of pure PVA–PVP blend and their complexes were examined by DSC to measure how the thermal transitions of the prepared films were affected by different concentration of Mg(ClO₄)₂. The ionic conductivity and dielectric behaviour were explored using A.C. impedance spectroscopy. The trend of ionic conductivity increases almost proportionally to the content of magnesium salt and can be related to an increase of amorphous phase at high level of dopant salt. The electrochemical stability of the optimum conducting blend polymer electrolyte is found to be ～3.5 V. The Mg²⁺ transference number for the sample with optimized conductivity was found to be 0.31.