Characterization of Polymer Electrolytes Based on Poly(vinylidene fluoride-co -hexafluoropropylene) and Lithium Triflate (original) (raw)
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All-solid batteries using polymer electrolytes have been accepted as a final target of lithium secondary batteries. This is because the polymer electrolytes in place of conventionally used organic electrolyte solutions are expected to demonstrate high safety performance against an accident such as thermal shock during utilization. Furthermore, the final system of all-solid batteries could be simplified without a sealed package, separator between electrodes, and any additional apparatus to assure safety. This advantage could contribute to the cost reduction of battery bodies and of the fabrication process.
Materials Research, 2014
Materials based on a mixture of poly(vinylidene fluoride) (PVDF), poly(2-hydroxyethyl methacrylate) (PHEMA) and LiClO 4 were produced to evaluate their ionic behavior and morphological structure to determine if they can be used as an electrolyte in electrical devices. FTIR chemical analysis results indicated the presence of interactions between PVDF, PHEMA and LiClO 4 . MDSC results showed that the transition temperatures of the polymers shifted to higher temperatures for systems containing high concentrations of each polymer. SEM images indicated that there was some miscibility between the polymers especially for the 25 and 75 wt. % compositions. In terms of the electrical performance, the ionic conductivity level of the electrolyte could be controlled by changing the composition of the system.
Chemical Science Transactions
Polymer electrolyte (PE) materials consisting of poly(vinylidene fluoride-cohexafluoropropylene) (PVDF-HFP) and zinc trifluoromethanesulfonate (zinc triflate) were prepared and characterized in order to determine the composition with an optimum electrical conductivity. PE films of pure PVDF-HFP and various compositions containing 5, 10, 15, 20 and 25 weight percent of zinc triflate in a polymer matrix of PVDF-HFP were synthesized and analyzed using complex impedance analysis, x-ray diffraction (XRD) and differential scanning calorimetry (DSC) studies. The composition containing 25 weight percent of zinc triflate in PVDF-HFP polymer matrix was found to exhibit an optimum electrical conductivity (σ) of 5.5×10-5 Scm-1 at room temperature (301 K).
Solid State Ionics, 2000
Diffusion coefficients of gel electrolytes composed of lithium salts, LiN(CF SO ) (Imide) and LiN(C F SO ) (BETI), 3 2 2 2 5 2 2 mixed solvent EC / DEC and copolymer PVDF-HFP have been measured using the pulsed-field gradient NMR in order to investigate the conduction mechanisms of the gel electrolytes. The diffusion values depended on the polymer to solution ratio of the gel. However, they were independent of the diffusion time in the range between 20 and 500 ms. This suggests there is no macroscopic blocking effect of the polymer as steric hindrance on the mobility in the migration range between 0.5 and 5 mm. The cation and anion diffusion values approximated each other with the increase in polymer fraction. Estimation of the relative change in carrier concentration using the diffusion and conductivity values confirmed that the dissociation degree of the Imide gels changed orderly depending on the polymer content, which may be due to some interaction between the mobile species and the polymer.
The complex of Poly (vinylidene fluoride-hexafluoro propylene) (PVDF-HFP), Poly (methyl methacrylate)-grafted natural rubber (MG49) (70/30) with lithium trifluoromethane sulfonate (LiCF 3 SO 3) based solid polymer electrolyte has been prepared using solution casting technique. The electrochemical impedance spectroscopy (EIS) has been used to measure the ionic conductivity. This work has demonstrated that the addition of an optimum content of LiCF 3 SO 3 enhance the ionic conductivity of polymer electrolyte films and conductivity values were found to depend upon the concentration of LiCF 3 SO 3. The highest ionic conductivity achieved at 1.97×10ˉ4 S cm-1 for 25 wt. % of LiCF 3 SO 3 at room temperature. By applying the temperature range from 303 K to 373 K the conductivity rise and the maximum conductivity obtained at 5.65×10-3 S cm-1 at 373 K. The interaction between Li ion and F atom in the structure of PVDF-HFP and O atom in MG49 resulting the formation of complex proved by the study of fourier transform infrared spectroscopy (FTIR). The amorphicity and crystallinity of electrolyte films have been characterized by x-ray diffraction (XRD) which indicates decrease in the degree of crystallinity by increasing of salt concentration. Scanning electron microscopy (SEM) appeals that there is no phase separation in the blend. Furthermore the nature of lithium salt has been found to influence the morphology of the polymer-blended electrolytes by improvement of surface morphology from rough to smooth with increasing salt content.
Li ION CONDUCTING POLYMER BASED ON POLYVINYLIDENE FLUORIDE AND Li TRIFLATE
Li ION CONDUCTING POLYMER BASED ON POLYVINYLIDENE FLUORIDE AND Li TRIFLATE. A Series of polymer electrolyte based on Polyvinylidene Fluoride (PVDF) for solid state rechargeable lithium battery has been prepared by solution casting technique. Lithium triflate salt was used as filler with various compositions. Bulk nature and surface morphology of the polymer electrolytes were studied by X-Ray Diffractometer (XRD) and Scanning Electron Microscope (SEM), respectively. The thermal properties of polymer and salt were confirmed by Differential Scanning Calorimeter (DSC). The electrical properties of electrolyte polymer membrane were studied by using impedance spectrometer. It was found that the highest ionic conductivity was obtained for PVDF + Li Triflate 10% (w/w) which is 4.5411 x 10-3 S/cm. It was also found that there was peak of each composition in the loss tangent suggests the presence of relaxing dipoles in the polymer electrolyte films. The peak shifts towards higher frequency si...
Ionic Conduction Properties of PVDF - HFP Type Gel Polymer Electrolytes with Lithium Imide Salts
Conduction properties of gel polymer electrolytes composed of lithium imide salts, LiN(CF 3 SO 2 ) 2 , LiN(C 2 F 5 -SO 2 ) 2 , and PVDF-HFP copolymer were investigated using the pulsed-field gradient NMR and complex impedance techniques. The diffusion coefficients of the gel decreased with an increase in the polymer fraction in the gel. Carrier concentration exhibited 3 orders of magnitude variation in the fraction change in polymer from 80% to 20%. These results suggest that the polymer interacts with the electrolyte to affect the carrier concentration and mobility of the gel electrolytes. The interactive effect of polymer would be detected in the measurements of spin-lattice relaxation time (T 1 ). The deviation of the symmetric curve of the temperature dependence of T 1 could be divided into two components, one was consistent with the component of solution and independent of the polymer fraction and the other depended on the polymer fraction in the gel.
Journal of Nanoscience and Technology
Polymers complexed with lithium salts are promising for use as solid electrolytes in solid-state lithium batteries. However, the key issue is the ionic conductivity and the process of enhancing it for better performance. Polyethylene glycol-based solid polymer electrolytes complexed with lithium salts are being investigated to explore their suitability in battery applications. In the present work, we report the investigations carried out on PEG-based solid polymer electrolyte complexed with lithium trifluoromethanesulfonate (LiCF3SO3). The ionic conductivity profile as a function of salt content is studied. The effect of the addition of inert nanofiller SiO2 is also investigated to understand the mechanism of enhancement of ionic conductivity. The preparation of the nanocomposite solid polymer electrolytes and characterization by other techniques like powder XRD, IR spectroscopy, thermal measurements and conductivity profile obtained from AC impedance measurements are discussed to get an insight into the mechanism of ion transport and the influence of the addition of nanofiller.
Ion conduction of branched polyethyleneimine–lithium bis(trifluoromethylsulfonyl) imide electrolytes
Electrochimica Acta, 2011
Ionic conductivity of polymer electrolytes containing branched poly (ethylene imine) (BPEI) and lithium bis(trifluoromethyl sulfonyl)imide (LiTFSI) was measured between temperatures of 20 and 70 • C and molar ratios of 20:1 and 400:1. The electrolytes were characterized by impedance spectroscopy, differential scanning calorimetry, and viscosity measurements. At room temperature, the maximum conductivity was 2 × 10 −6 S/cm at a molar ratio of 50:1. The molar conductivity of the electrolytes displayed first a minimum and then a maximum upon increasing salt concentration. A proportionality of molar conductivity to segmental mobility was seen from glass transition temperature and viscosity measurements. Analysis of the Walden product and isoviscosity conductivity showed that the percentage of ions bound in ion pairs increased at low concentrations below 0.1 mol/kg. The average dipole moment decreased with salt concentration. The temperature dependence of the ionic conductivity showed an Arrhenius behavior.
Ionic conduction in P(VDF-HFP)/PVDF–(PC + DEC)–LiClO 4 polymer gel electrolytes
Electrochimica Acta, 2004
Gel polymer electrolytes composed of poly(vinylidene fluoride-hexafluoropropylene) copolymer, poly(vinylidene fluoride) polymer, PC + DEC as plasticizer and LiClO 4 as salt have been synthesized by solvent casting technique with varying the plasticizer-salt concentration ratio systematically. Complex impedance spectroscopy has been carried out to investigate ionic conduction in P(VDF-HFP)-(PC + DEC)-LiClO 4 and PVDF-(PC + DEC)-LiClO 4 electrolyte systems. Transport number measurements have been made by Wagner's polarization technique. With all other parameters same, P(VDF-HFP) electrolytes exhibit higher ionic conductivity and transport number as compared to PVDF based electrolytes which could be attributed to higher degree of amorphicity in the P(VDF-HFP) system. XRD and FTIR studies have been conducted to investigate the structural and complexation in the polymer gel electrolytes. Microstructural studies by SEM exhibit higher amorphicity and solvent retention capability for P(VDF-HFP)-(PC + DEC)-LiClO 4 system than those of PVDF-(PC + DEC)-LiClO 4 system.