Ionic conductivity of LiX-oligo(ethylene oxide)-perfluoro polymer ternary hybrids

Polymeric solid electrolytes were prepared from inorganic lithium salts, endo-acetylated oligo(ethylene oxide) and polyanions with perfluoro(ethylene) main chain. High ionic conductivity was found when these ternary hybrids took micro-segregated structures with continuous cylindrical conduction columns of lithium salt-oligo(ethylene oxide) in the sea of perfluoro-poly(electrolytes). The ionic conductivity of more than 10^?5 S/cm was established at room temperature without affecting the processibility and flexibility of resulting hybrid films.     

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.     

Ionic conductivity and battery characteristic studies on PEO+NaClO3 polymer electrolyte

Solid polymer electrolyte films based on poly (ethylene oxide) PEO complexed with NaClO₃ have been prepared by a solution-cast technique. The solvation of Na⁺ ion with PEO is confirmed by XRD and IR studies. Measurements of the a.c. conductivity in the temperature range 308 – 378 K and the transference numbers have been carried out to investigate the charge transport in this polymer electrolyte system. Transport number data show that the charge transport in this polymer electrolyte system is predominantly due to ions. The highest conductivity (2.12.10⁻⁴ S/cm) has been observed for the 70:30 composition. Using the polymer electrolyte solid state electrochemical cells have been fabricated. The various cell parameters are evaluated and reported.     

Ionic conductivity of electrolytes based on star-branched poly(ethylene oxide) with high concentration of lithium salts

Electrolytes based on star-branched poly(ethylene oxide) with lithium bis(trifluoromethanesulfone)imide LiTFSI and lithium iodide salts were prepared by casting from solution. The electrical properties of electrolytes subjected to various heating and cooling runs were studied by impedance spectroscopy and impedance spectroscopy simultaneous with optical microscope observation. Differential scanning calorimetry was used for additional characterization. The results indicate that in electrolytes with high content of salt, values of ionic conductivity comparable to that of dilute electrolytes can be achieved. Moreover, electrolytes with high amount of salt seem to show weaker temperature dependence of conductivity. Promising results in terms of ionic conductivity were obtained for mixture of LiTFSI and lithium iodide. A few problems which may decrease the performance of studied system as a solid electrolyte were also identified, from which changes of physical properties of samples subjected to thermal cycles and aging seem to be the most important ones.     

Ionic conductivity of polymer electrolytes based on phosphate and polyether copolymers

Linear polyphosphate random copolymers (LPC) composed of phosphate as a linking agent with poly(ethylene glycol) (PEG) and/or poly(tetramethylene glycol) (PTMG) were synthesized to increase local segmental motion for improved ion transport. Ionic conductivity and thermal behavior of LPC series–LiCF₃SO₃ complexes were investigated with various compositions, salt concentrations and temperatures. The PEG(70)/PTMG(30)/LiCF₃SO₃ electrolyte exhibited ionic conductivity of 8.04×10⁻⁵ S/cm at 25°C. Salt concentration with the highest ionic conductivity was considerably dependent on EO/TMO compositions in LPC series–salt systems. Relationship between solvating ability and chain flexibility with various compositions and salt concentrations was investigated through theoretical aspects of the Adam–Gibbs configurational entropy model. Temperature dependence on the ionic conductivity in LPC6 series–salt systems suggested the ion conduction follows the Williams–Landel–Ferry (WLF) mechanism, which is confirmed by Vogel–Tamman–Fulcher (VTF) plots. The ionic conductivity was affected by segmental motion of the polymer matrix. VTF parameters and apparent activation energy were evaluated by a non-linear least square minimization method. These results suggested that the solvating ability of the host polymer might be a dominant factor to improve the ionic conductivity rather than chain mobility.     

Ionic conductivity studies in composite solid polymer electrolytes based on methylmethacrylate

The preparation and characterization of composite polymer electrolytes of PMMA-LiClO₄-DMP for different concentrations of CeO₂ have been investigated. FTIR studies indicate complex formation between the polymer, salt and plasticizer. The electrical conductivity values measured by a.c. impedance spectroscopy are found to depend upon the CeO₂ concentration. 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.     

FTIR and conductivity studies of PVC based polymer electrolyte systems

Poly (vinylchloride) (PVC)-LiBF₄ polymer electrolytes plasticized with DBP in different mole ratios have been studied by FTIR and Impedance Spectroscopic techniques. The complexation has been confirmed from FTIR studies. The maximum room temperature conductivity (2.1·.10⁻⁷ S·.cm⁻¹) has been observed for PVC-LiBF₄-DBP (10-5-85 mole%) complex. 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.     

Structural, vibrational, thermal, and conductivity studies on proton-conducting polymer electrolyte based on poly (N-vinylpyrrolidone)

The proton-conducting polymer electrolytes based on poly (N-vinylpyrrolidone) (PVP), doped with ammonium chloride (NH₄Cl) in different molar ratios, have been prepared by solution-casting technique using distilled water as solvent. The increase in amorphous nature of the polymer electrolytes has been confirmed by XRD analysis. The FTIR analysis confirms the complex formation of the polymer with the salt. A shift in glass transition temperature (T _g) of the PVP/NH₄Cl electrolytes has been observed from the DSC thermograms which indicates the interaction between the polymer and the salt. From the AC impedance spectroscopic analysis, the ionic conductivity of 15?mol% NH₄Cl-doped PVP polymer complex has been found to be maximum of the order of 2.51?×?10^?5?Scm^?1 at room temperature. The dependence of T _g and conductivity upon salt concentration has been discussed. The linear variation of the proton conductivity of the polymer electrolytes with increasing temperature suggests the Arrhenius type thermally activated process. The activation energy calculated from the Arrhenius plot for all compositions of PVP doped with NH₄Cl has been found to vary from 0.49 to 0.92?eV. The dielectric loss curves for the sample 85?mol% PVP:15?mol% NH₄Cl reveal the low-frequency ?? relaxation peak pronounced at high temperature, and it may be caused by side group dipoles. The relaxation parameters of the electrolytes have been obtained by the study of Tan?? as a function of frequency.     

Synergistic film-forming effect of oligo(ethylene oxide)-functionalized trimethoxysilane and propylene carbonate electrolytes on graphite anode

Oligo(ethylene oxide)-functionalized trialkoxysilanes can be used as novel electrolytes for high-voltage cathode, such as LiCoO₂ (4.35 V) and Li_1.2Ni_0.2Mn_0.6O₂ (4.6 V); however, they are not well compatible with graphite anode. In this study, a synergistic solid electrolyte interphase (SEI) film-forming effect between [3-[2-(2-methoxyethoxy)ethoxy]propyl]-trimethoxysilane (TMSM2) and propylene carbonate (PC) on graphite electrode was investigated. Excellent SEI film-forming capability and cycling performance was observed in graphite/Li cells using the electrolyte of 1 M LiPF₆ in the binary solvent of TMSM2 and PC, with the PC content in the range of 10–30 vol.%. Meanwhile, the graphite/Li cells delivered higher specific capacity and better capacity retention in the electrolyte of 1 M LiPF₆ in TMSM2 and PC (TMSM2:PC = 9:1, by vol.), compared with those in the electrolyte of 1 M LiPF₆ in TMSM2 and EC (TMSM2:EC = 9:1, by vol.). The synergistic SEI film-forming properties of TMSM2 and PC on the surface of graphite anode was characterized by electrolyte solution structure analysis through Raman spectroscopy and surface analysis detected by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and Fourier transform infrared spectroscopy (FT-IR) analysis.     

Characterization of nanocomposite polymer electrolyte based on P(ECH-EO)

ZrO₂ nanoparticles have been prepared by poly acrylamide gel route. The synthesized nanosized ZrO₂ have been incorporated into plasticized polymer electrolyte (PPE), P(ECH-EO): LiClO₄: γ-BL system to understand the effect of ZrO₂ on the ionic conductivity. The X-ray diffraction pattern of the synthesized ZrO₂ nanoparticles reveals the crystalline phase. The X-ray diffraction patterns of P(ECH-EO) based NCPEM confirm the polymer-salt-nanoparticle complexation. The scanning electron microscope image of NCPEM confirms that the ZrO₂ nanoparticles were distributed uniformly in the polymer matrix. The presence of nano filler has increased the ionic conductivity and the maximum dc conductivity value is found to be 6.24×10⁻⁶ S cm⁻¹ at 303 K for 96(PPE): 4ZrO₂ (mol%).     

Synthesis and morphological change in poly(ethylene oxide)-sodium chlorate based polymer electrolyte complex with polyaniline

The composites of polyethylene oxide:polyaniline:sodium chlorate is prepared by stirring with anhydrous acetonitrile for 5-6 h to form homogeneous solutions/gels at different weight percentages. The composites are characterized by FTIR and SEM. The predominant peaks that appeared in FTIR spectra confirm the formation of PEO:PANI:NaClO₄ composites. It is found from the SEM studies that there is a significant change in the morphology of various weight percentages of NaClO₄ in PEO-PANI matrix, i.e. from ellipsoidal to square. DC conductivity behavior is seen due to hopping of polarons from one localized state to another that can be confirmed by Mott theory. It is observed from the DC conductivity and SEM studies that these composites can be promising candidates for solid state electrolytes.     

Effect of fillers on magnesium–poly(ethylene oxide) solid polymer electrolyte

A solid polymer electrolyte (SPE) film consisting of poly(ethylene oxide) (PEO) with magnesium chloride as electrolytic salt and B₂O₃ as the filler has been prepared by solution casting technique. The polymeric film was flexible and self-standing with proper mechanical strength and studied for application in a solid-state rechargeable magnesium battery. The interactions between the filler and PEO chains are studied by differential scanning calorimeter and Fourier transform infrared techniques. Composition of SPE is optimized, and maximum conductivity is obtained at 2 wt% B₂O₃. Filler seems to increase the number of free magnesium cations by decoordinating the bond between magnesium cations and ether oxygen of PEO. Cyclic voltammetry results show the reversible capability of magnesium electrode. Solid-state magnesium cell employing magnesium anode, SPE, and manganese oxide was assembled, and its open circuit voltage is found to be 1.9 V.     

Structural and ionic conductivity studies on proton conducting polymer electrolyte based on polyvinyl alcohol

An attempt has been made to prepare a new proton conducting polymer electrolyte based on polyvinyl alcohol (PVA) doped with NH₄NO₃ by solution casting technique. The complex formation between polymer and dissociated salt has been confirmed by X-ray diffraction analysis. The ionic conductivity of the prepared polymer electrolyte has been found by ac impedance spectroscopic analysis. The highest ionic conductivity has been found to be 7.5 × 10⁻³ Scm⁻¹ at ambient temperature for 20 mol% NH₄NO₃-doped PVA with low activation energy (~0.19 eV). The temperature-dependent conductivity of the polymer electrolyte follows an Arrhenius relationship, which shows hopping of ions in the polymer matrix.     

Vibrational spectroscopic and electrochemical characteristics of poly (propylene glycol)-silver triflate polymer electrolyte system

Fourier transform infrared spectroscopic and electrochemical complex impedance studies have been carried out on a series of complexes containing poly(propylene glycol) of molecular weight 4,000 and silver triflate (AgCF₃SO₃) salt corresponding to the ether oxygen to metal cation ratios (O : M) in the range 16:1 to 12:1. The formation of ion pairs and aggregates noticed in the case of specimens having high salt concentrations as well as the complete coordination of the cation with the ether oxygen at low salt concentrations within the PPG4000-AgCF₃SO₃ polymer electrolyte system have been confirmed. The appearance of two weak triflate bands at 1,032 and 1,272 cm⁻¹ in the absorption spectra in respect of low salt concentrations is indicative of the fact that triflate ions are free within the polymer matrix. The room temperature (298 K) electrical conductivity is found to increase with increasing ether oxygen content while exhibiting the maximum value of 7.1 × 10⁻⁵ Scm⁻¹ possibly due to silver ionic transport in the case of the typical composition having an O : M ratio of 16:1.     

Stability domain of a complexed lithium salt-poly(ethylene oxide) polymer electrolyte

The redox stability domain of a polyethylene oxide-lithium trifluoromethanesulphonate polymer electrolyte has been investigated using low-sweep-rate voltammetry, in the range 100–170°C. Below 140°C, its voltage stability window is in excess of 3.3 volts, making it a candidate for use with practical electrochemical couples. The electrolyte is not, however, a pure cation conductor, and problems associated with the observed significant anion mobility must be overcome in order to improve the polymer's suitability as a solid-state electrolyte for battery applications.     

Synthesis and characterization of proton-conducting polymer electrolyte based on polyacrylonitrile (PAN)

Solid polymer electrolytes based on polyacrylonitrile (PAN) doped with ammonium iodide (NH₄I) have been prepared by solution casting method with different molar ratios of polymer and salt using DMF as solvent. The XRD pattern confirms the dissociation of salt. The FTIR analysis confirms the complex formation between the polymer and the salt. A shift in glass transition temperature (T _g ) of the PAN/NH₄I electrolytes has been observed from the DSC thermograms, which indicates the interaction between the polymer and the salt. The conductivity analysis shows that the polymer electrolyte with 20 mol% NH₄I has the highest conductivity equal to 1.106 × 10⁻³ S cm⁻¹ at room temperature. The activation energy (E _a ) has been found to be low for the highest conductivity sample. The dielectric permittivity (ε*) and modulus (M*) have been calculated from the alternating current (AC) impedance spectroscopy in the frequency range 42 Hz–1 MHz. The DC polarization measurement shows that the conductivity is mainly due to ions.

     

Ionic conductivity studies of chitosan-based polymer electrolytes doped with adipic acid

Chitosan acetate–adipic acid film polymer electrolytes have been prepared by the solution cast technique. The highest conductivity is 1.4 × 10⁻⁹ S cm⁻¹ for 35 wt.% of adipic acid at room temperature. The sample with highest conductivity has the lowest activation energy. Calculations using the Rice and Roth model provide number of mobile ions, η. The conductivity is dependent on the diffusion coefficient and mobility.     

Development of dry polymer electrolyte based on polyethylene oxide with co-bridging agent crosslinked by electron beam

Polyethylene oxide (PEO)-based electrolytes were crosslinked using electron beam (EB) irradiation. The gel contents of a polymer film were increased after irradiation doses of 0, 140, 280, and 420 kGy, with ionic conductivities of 0.831, 1.55, 6.08, and 7.95 (× 10^? 5) S cm^? 1 at 40 °C, respectively. The slight decrease in conductivity at higher temperatures after irradiation is due to the retardation of polymer motion by crosslinking. The electrolyte with higher EB dose amount exhibits higher conductivity due to stabilization of the amorphous state. The EB crosslinking with a co-bridging agent shows enhanced conductivities of 4.71, 6.59, and 7.18 (× 10^? 5) S cm^? 1 at 40 °C, after irradiation with 140, 280, and 420 kGy. Addition of the co-bridging agent is effective for developing a crosslinked structure with a smaller EB dose. Tensile strength becomes two to three times higher with irradiation compared to the non-treated polymer. Combination of the EB technique with a co-bridging agent is a simple and effective method to prepare strong dry polymer electrolyte films with improved room temperature conductivity.     

Properties of a gel polymer electrolyte based on lithium salt with poly(vinyl butyral)

Poly(vinyl butyral) (PVB) is of particular interest because of its low cost, extremely wide temperature work range (? 20 to 120 °C), and efficient chemical stability. In this study, a gel polymer electrolyte (GPE) containing Li⁺ ions was fabricated by using dimethylacetylamine (DMA), lithium perchlorate (LiClO₄), and PVB. The experimental results indicated that a highly transparent GPE with a high ionic conductivity (σ) could be obtained by mixing glue (DMA with a PVB content of 10 wt%) with a LiClO₄ content of 6 wt%. It was found that the ionic conductivity (σ) of the GPE depended on the LiClO₄ content, and the GPE with a LiClO₄ content of 6 wt% exhibited a maximum σ of 7.73 mS cm^?1, a viscosity coefficient of 3360 mPa s, and a transmittance greater than 89% (visible region) at room temperature. Furthermore, PVB improved the electrolyte solution leakage, and the LiClO₄ was used as an ion supply source for the high σ of the GPE.     

Ionic conductivity and electrochemical stability of poly(methylmethacrylate)-poly(ethylene oxide) blend-ceramic fillers composites

The role of inorganic ceramic fillers namely nanosized Al₂O₃ (15-25 nm) and TiO₂ (10-14 nm) and ferroelectric filler SrBi₄Ti₄O₁₅ (SBT CIT) (0.5 μm) synthesized by citrate gel technique (CIT) on the ionic conductivity and electrochemical properties of polymer blend 15 wt% PMMA+PEO₈:LiClO₄+2 wt% EC/PC electrolytes were investigated. Enhancement in conductivity was obtained with a maximum of 0.72×10⁻⁵ S cm⁻¹ at 21 °C for 2 wt% of SrBi₄Ti₄O₁₅ (SBT CIT) composite polymer electrolyte. The lithium-ion transport number and the electrochemical stability of the composite polymer electrolytes at ambient temperature were analyzed. An enhancement in electrochemical stability was observed for polymer composites containing 2 wt% of SrBi₄Ti₄O₁₅ (SBT CIT) as fillers.