Cellulose triacetate‐based polymer gel electrolytes

New composite polymer gels were obtained from cellulose triacetate (CTA), N‐methyl‐N′‐propylpyrrolidinium bis(trifluoromethanesulfonyl)imide (Pyr_1,3TFSI), and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI). Analysis by differential scanning calorimeter and scanning electron microscope showed that the ionic gel consisting of CTA, Pyr_1,3TFSI, and LiTFSI formed a completely homogeneous phase at the molar ratio of CTA/Pyr_1,3TFSI/LiTFSI = 1/3/1.5. The ionic conductivity of the polymer gel was significantly enhanced by the presence of LiTFSI. FTIR study strongly implies that the interaction of lithium ion with the carbonyl group of CTA could be responsible for the increase in conductivity. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Novel nanocomposite of poly(acrylonitrile‐co‐glycidyl methacrylate) crosslinked with Jeffamine‐functionalized multiwalled carbon nanotubes as gel polymer electrolytes

Multiwalled carbon nanotubes (MWCNTs) were functionalized with α,ω‐diamino poly(propylene oxide) (Jeffamine) of different molecular weights and crosslinked with poly(acrylonitrile‐co‐glycidyl methacrylate) [P(AN‐GMA)] to prepare a novel nanocomposite for applications in gel polymer electrolytes (GPEs). The synthesized copolymer was characterized by ¹H‐NMR, Fourier transform infrared, and thermal analysis. Scanning electron microscope observation revealed that the Jeffamine‐functionalized MWCNTs distributed uniformly in the nanocomposite membrane. The mechanical behaviors of the nanocomposite membranes were investigated. It was found that the crosslinked nanocomposite membranes of P(AN‐GMA) and Jeffamine‐functionalized MWCNTs exhibited much higher mechanical strength than the counterpart nanocomposite obtained by physical blending. Moreover, the weight content and molecular weights of Jeffamine had an effect on the mechanical properties of the nanocomposites. Differential scanning calorimeter measurements showed that the crosslinked nanocomposite membranes were amorphous. GPEs based on the nanocomposite were prepared and characterized by complex impedance measurements. The GPE based on the nanocomposite of P(AN‐GMA) crosslinked with 6 wt % of MWCNTs functionalized by Jeffamine D400 showed an ionic conductivity of about 3.39 × 10^?4 S cm^?1 at 25°C, which is much higher than the counterpart nanocomposite of physically blended P(AN‐GMA) and MWCNTs. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Molecular mobility in comb‐like copolymethacrylates with chalcone‐containing side‐chains

The molecular mobility of comb‐like copolymers of amyl methacrylate with N‐methacryloyl‐(4‐amino‐4′‐bromochalcone) with various concentrations (20, 30, 40, 50 and 60 mol%) of chalcone‐containing comonomer was studied using dielectric spectroscopy. It was found that chalcone chromophores participate in two forms of molecular mobility: cooperative motion in the rubbery state (δ‐relaxation) and local motion in the glassy state (β‐relaxation). In addition, α‐, β₁‐ and γ‐processes, being related to cooperative segmental mobility, to local motion of ester groups adjacent to the backbone and to local motion of terminal side‐groups, respectively, were evident. The molecular mobility of the β₁‐, β‐ and γ‐processes changed slightly with the concentration of chromophore groups. For the δ‐ and α‐processes, the glass transition temperatures, T_δ and T_g, increased with the molar fraction of chalcone groups, the difference between them remaining nearly constant (ca 55 °C). The T_δ values obtained should be considered as optimal temperatures for the corona‐poling of the chromophore‐containing polymers for the preparation of second‐order nonlinear optical polymer films with non‐centrosymmetric arrangement of chromophore groups. Copyright © 2011 Society of Chemical Industry     

Mechanical properties and ionic conductivity of gel polymer electrolyte based on poly(vinylidene‐fluoride‐co‐hexafluoropropylene)

The main thermodynamic parameters were evaluated for the dextran/methoxy ethylene glycol (MEG) system by viscosity measurements at 25, 30, 35, 40, and 45°C. The long-range and short-range interaction parameters were determined by extrapolation methods, i.e, Kurata-Stockmayer-Fixman, Berry, and Inagaki-Suzuki-Kurata equations. Calculated values, as well as the unperturbed root-mean-square end-to-end distance and hydrodynamic expansion factor, were interpreted mainly on the basis of hydrogen-bond formation between polymer segments and dextran/MEG molecules in solution. The thermodynamic interaction parameter was also evaluated for the same system. The theta temperatures were obtained from the temperature dependence of the interaction parameter, dependence of (1/2-χ) and the second virial coefficient in the temperature interval of 25 and 45°C for the system and quite a good accordance was indicated with the calculated values evaluated via extrapolation and interpolation methods. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 948–953, 2001     

Ionic conductivity and physical stability study of gel nework polymer electrolytes

Gel polymer electrolytes (GPE) were prepared by a crosslinking reaction between poly(ethylene glycol) and a crosslinking agent with three isocyanate groups in the presence of propylene carbonate (PC) and ethylene carbonate (EC) or their mixture, and their ionic conducting behavior was carefully investigated. When the plasticizer amount was fixed, the ionic conductivity was greatly influenced by the nature of plasticizers. It was found that the conductivity data followed the Arrhenius equation in the GPE. Whatever plasticizer was used, a maximum ambient conductivity was found at a salt concentration near [Li⁺]/[EO] equal to 0.20. The physical stability of GPE was studied qualitatively by weight loss of GPE under pressure. It was shown that the stability was greatly affected by the network structure of the GPE and the most stable one in our research was the GPE containing the PEO₁₀₀₀ segment, which has a strong interaction between network and plasticizers. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2957–2962, 2000     

A study on polyurethane/acrylate crosslinked gel polymer electrolytes

2,4‐Toluene diisocyanate, poly(propylene glycol), poly(ethylene glycol) (PEG) and 2‐hydroxyethyl methacrylate were used to synthesize PEG–UA (urethane acrylate) monomer. The crosslinked polymer and gel polymer electrolytes were prepared in dioxane by free radical polymerization. The swelling behaviour, thermal degradation properties, morphology and ionic conductivity of the gel polymer electrolytes were investigated. With decrease in the proportion of dioxane used, the synthesized polymer's network density increased, its affinity with a solution of 1 M LiClO₄ in propylene carbonate (PC) decreased, and more microgel which diffused in the network. At the same time, the conductivity increased and reached 4 × 10^?4 S cm^?1 at 25 °C. Copyright © 2003 Society of Chemical Industry     

Solid polymer electrolytes. XI. Preparation,characterization and ionic conductivity of new plasticized polymer electrolytes based on chemical‐covalent polyether–siloxane hybrids

A new hybrid polymer electrolyte system based on chemical‐covalent polyether and siloxane phases is designed and prepared via the sol–gel approach and epoxide crosslinking. FT‐IR, ¹³C solid‐state NMR, and thermal analysis (differential scanning calorimetry (DSC) and TGA) are used to characterize the structure of these hybrids. These hybrid films are immersed into the liquid electrolyte (1M LiClO₄/propylene carbonate) to form plasticized polymer electrolytes. The effects of hybrid composition, liquid electrolyte content, and temperature on the ionic conductivity of hybrid electrolytes are investigated and discussed. DSC traces demonstrate the presence of two second‐order transitions for all the samples and show a significant change in the thermal events with the amount of absorbed LiClO₄/PC content. TGA results indicate these hybrid networks with excellent thermal stability. The EDS‐0.5 sample with a 75 wt % liquid electrolyte exhibits the ionic conductivity of 5.3 × 10^?3 S cm^?1 at 95°C and 1.4 × 10^?3 S cm^?1 at 15°C, in which the film shows homogenous and good mechanical strength as well as good chemical stability. In the plot of ionic conductivity and composition for these hybrids containing 45 wt % liquid electrolyte, the conductivity shows a maximum value corresponding to the sample with the weight ratio of GPTMS/PEGDE of 0.1. These obtained results are correlated and used to interpret the ion conduction behavior within the hybrid networks. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1000–1007, 2006     

Crystallinity,thermal properties,morphology and conductivity of quaternary plasticized PEO‐based polymer electrolytes

Quaternary plasticized solid polymer electrolyte (SPE) films composed of poly(ethylene oxide), LiClO₄, Li_1.3Al_0.3Ti_1.7(PO₄)₃, and either ethylene carbonate or propylene carbonate as plasticizer (over a range of 10–40 wt%) were prepared by a solution‐cast technique. X‐ray diffraction (XRD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS) indicated that components such as LiClO₄ and Li_1.3Al_0.3Ti_1.7(PO₄)₃ and the plasticizers exerted important effects on the plasticized quaternary SPE systems. XRD analysis revealed the influence from each component on the crystalline phase. DSC results demonstrated the greater flexibility of the polymer chains, which favored ionic conduction. SEM examination revealed the smooth and homogeneous surface morphology of the plasticized polymer electrolyte films. EIS suggested that the temperature dependence of the films' ionic conductivity obeyed the Vogel–Tamman–Fulcher (VTF) relation, and that the segmental movement of the polymer chains was closely related to ionic conduction with increasing temperature. The pre‐exponential factor and pseudo activation energy both increased with increasing plasticizer content and were maximized at 40 wt% plasticizer content. The charge transport in all polymer electrolyte films was predominantly reliant on lithium ions. All transference numbers were less than 0.5. Copyright © 2006 Society of Chemical Industry     

Effect of PBMA on PVC‐based polymer blend electrolytes

Poly(vinyl chloride) (PVC)—poly(butyl methacrylate) (PBMA) blended polymer electrolytes with lithium perchlorate (LiClO₄) as the complexing salts are prepared by solution casting technique. The addition of PBMA into PVC matrix is found to induce considerable changes in physical and electrical properties of the polymer electrolytes. Addition of PBMA into PVC matrix is found to increase the conductivity by two orders of magnitude (1.108 × 10^?5 S cm^?1) when compared with that of the pristine PVC polymer electrolyte (10^?7 S cm^?1). Structural, thermal, mechanical, morphological, and polymer–salt interactions are ascertained from X‐ray diffraction (XRD), thermogravimetry/differential thermal analysis (TG/DTA), mechanical analysis, scanning electron microscope (SEM), and Fourier transform infrared spectroscopy (FTIR) respectively. A thermal stability upto 250 °C is asserted from the TG/DTA analysis. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 44939.     

Electrochemical studies on composite gel polymer electrolytes for lithium sulfur‐batteries

Poly(ethylene oxide)‐based composite gel polymer electrolytes (CGPE's) were prepared for various concentrations of magnesium aluminate (MgAl₂O₄) and LiTFSI as salt with a combination of 1,3‐dioxolane (DOL) and tetraethylene glycol dimethyl ether (TEGDME) as plasticizer by a simple solution casting technique. The addition of plasticizers has significantly improved the ionic conductivity of the gel electrolytes. The prepared CGPEs were subjected to scanning electron microscopy, thermal, and FT‐IR analysis. The electrochemical properties such as ionic conductivity, compatibility, and charge–discharge behavior have also been studied. Preliminary studies revealed that the prepared CGPE can be employed as a potential electrolyte for lithium–sulfur (Li–S) batteries. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44594.     

Ionic conductivity of polymer electrolytes and future applications

Polymer electrolytes are solvent-free ion-conducting polymers and provide new and attractive materials in both polymer chemistry and electrochemistry. A proper understanding of ion dissociation and ion transport in such polymers is necessary for their application as solid electrolytes in electrochemical devices. Ionic conduction behaviour in polymer electrolytes is described here in relation to the characteristic properties. Of special interest is the ability of polymer electrolytes to include various kinds of electroactive molecules within them. The combination of this ability with their high ionic conductivity has enabled polymer electrolytes to be used as media for electrochemical syntheses and redox reactions.     

Polymer gel electrolytes prepared from P(EG‐co‐PG) and their nanocomposites using organically modified montmorillonite

Polymer gel electrolytes were prepared by thermal crosslinking reaction of a series of acrylic end‐capped poly(ethylene glycol) and poly(propylene glycol) [P(EG‐co‐PG)] having various geometries and molecular weights. Acrylic end‐capped prepolymers were prepared by the esterification of low molecular weight (M_n: 1900–5000) P(EG‐co‐PG) with acrylic acid. The linear increase in the ionic conductivity of polymer gel electrolyte films was observed with increasing temperature. The increase in the conductivity was also monitored by increasing the molecular weight of precursor polymer. Nanocomposite electrolytes were prepared by the addition of 5 wt % of organically modified layered silicate (montmorillonite) into the gel polymer electrolytes. The enhancement of the ionic conductivity as well as mechanical properties was observed in the nanocomposite systems. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 894–899, 2004     

Study on morphology behavior of PVDF‐based electrolytes

Three nonelectrolyte samples and one gel polymer electrolyte sample were prepared from poly(vinylidene fluoride) (PVDF), propylene glycol carbonate (PC), and LiClO₄ in the present article. Fourier transform infrared spectroscopy, dynamic mechanical analysis, differential scanning calorimetry, thermogravimetric analysis, X‐ray diffraction, and scanning electron microscopy were used to study morphology structure of all the samples. Results showed that there were great interactions among PVDF, PC, and lithium salt, which led to different morphology properties of different samples. Interactions between PVDF and PC mainly occurred on the surface area of PVDF crystalline, while interactions between PC, PVDF, and lithium salt mainly occurred in the amorphous area. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3839–3842, 2004     

NMR measurements of self diffusion in polymer gel electrolytes

The pulsed field gradient NMR spin-echo technique has been used to measure the self diffusion coefficients of solvent molecules, Li⁺ cations and CF₃SO₃⁻¹ anions in polyvinylidene fluoride (PVDF) gel electrolytes incorporating liquid electrolytes based on either N,N-dimethylformamide (DMF) or tetraglyme (TG) and lithium triflate (LiT). Using the Nernst–Einstein equation with the NMR diffusivities, calculated values for the ionic conductivity were obtained and compared with those determined by ac conductivity measurements to provide estimates of ionic association. These results for the gel electrolytes are compared with those for the corresponding liquid electrolytes, over a range of salt concentrations and temperatures. In general terms, the comparisons support the simple conclusion that regions of liquid electrolyte exist within the gel electrolytes, consistent with limited measurements of the transverse relaxation time T₂ on these systems, which are also reported. There are, however, some small but significant differences between the behaviours of the gel electrolytes and the liquid electrolytes and these are discussed.     

Preparation and evaluation of two kinds of solid polymer electrolytes made from crosslinked poly(ether urethane) elastomers consisting of a comb‐like and a hyperbranched polyether

Two novel polyethers, one comb‐like and another hyperbranched, were synthesized by the cationic ring‐opening polymerization of 3‐(methoxy(triethylenoxy))methyl‐ and 3‐(hydroxy‐(triethylenoxy))methyl‐3′‐methyloxetane, respectively. The former reacted with a multifunctional isocyanate and the latter with a difunctional isocyanate to give rise to the corresponding crosslinked poly(ether urethane) elastomers, PCEU and PHEU. Accordingly, two kinds of solid polymer electrolytes (SPEs) were prepared from these two elastomers in situ in the presence of lithium salt trifluoromethanesulfonimide. It was found that the PCEU‐based SPEs shows a higher ionic conductivity than that PHEU‐based ones due to its more mobile pendent chains and appropriate crosslinking density in the polymeric network. The maximum ionic conductivities of 1.4 × 10^?5 S/cm at 30°C and 3.5 × 10^?4 S/cm at 80°C were attained at the molar ratio of O/Li = 7.5. The DSC measurements clearly demonstrated that PCEU indeed possesses the more flexible chain motion ability than PHEU. The electrochemical stability window of PCEU, which is 1.7–4.0 V was measured by cyclic voltammogram. Additionally, the significantly high decomposition temperature as evidenced by TGA analyses endowed these SPEs a good safe performance. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Ionically conductive polymer gel electrolytes consisting of crosslinked methacrylonitrile and organic electrolyte

To develop a highly ion‐conductive polymer electrolyte, we copolymerized methacrylonitrile (MAN) with ethylene glycol dimethacrylate (EGDMA) in propylene carbonate that contained tetraethylammonium tetrafluoroborate (TEATFB), changing the TEATFB concentration and the MAN/EGDMA molar ratio. We characterized the obtained polymer gel electrolytes with complex impedance analysis and cyclic voltammetry, intending to apply them to electric double‐layer capacitors. The ionic conductivities of the polymer gel electrolytes were dependent on the TEATFB concentration, the temperature, and particularly the crosslinking degree. The polymer gel electrolytes in this system exhibited high room‐temperature conductivities (>10^?3 S/cm). Furthermore, these polymer electrolytes showed good electrochemical stability windows ranging from ?4.0 to +4.0 V versus Ag. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2655–2659, 2002     

Magnetic resonance and conductivity study of gelatin-based proton conductor polymer electrolytes

This work report results from proton nuclear magnetic resonance (NMR), continuous-wave (CW-EPR) and pulsed electron paramagnetic resonance (P-EPR) and complex impedance spectroscopy of gelatin-based polymer gel electrolytes containing acetic acid, cross-linked with formaldehyde and plasticized with glycerol. Ionic conductivity of 2 × 10⁻⁵ S/cm was obtained at room temperature for samples prepared with 33 wt% of acetic acid. Proton (¹H) line shapes and spin-lattice relaxation times were measured as a function of temperature. The NMR results show that the proton mobility is dependent on acetic acid content in the plasticized polymer gel electrolytes. The CW-EPR spectra, which were carried out in samples doped with copper perchlorate, indicate the presence of the paramagnetic Cu²⁺ ions in axially distorted sites. The P-EPR technique, known as electron spin echo envelope modulation (ESEEM), was employed to show the involvement of both, hydrogen and nitrogen atoms, in the copper complexation of the gel electrolyte.     

Mechanically robust and highly electrochemical performance of polyethylene oxide gel polymer electrolyte

Synthesizing high-performance of gel polymer electrolytes (GPEs) with simple methods and common materials has long been a crucial concern for lithium-ion batteries. Here, the poor mechanical properties of polyethylene oxide (PEO) based GPEs were overcome by introducing strong hydrogen bond between PEO and polyacrylic acid (PAA). Easy-available PEO/PAA membranes were prepared though hot processing approach without use of organic solvent during all processes. The mechanical properties and crystalline of dry composites could be tuned by the addition content of PAA. After quick absorbing electrolyte in 30 min, the tensile strength and elongation at break of the GPEs composites are ranged from 0.07 to 0.63 MPa, and 525% to 722%. Moreover, the lithium-ion conductivity and transference number with 30 wt% addition of PAA reach up to 1.66 and 0.58 mS/cm, respectively. After 500 cycling at 0.5 C, the discharge specific capacity and the capacity retention rate are still up to 134.1 mAh/g and 88.7%, respectively. This research proves the great possibility of applying environmentally friendly method, low cost, and high electrochemical performances of PEO/PAA based GPEs in the lithium batteries.     

Structure and ionic conductive properties of polydioxolane–polyurethane‐based electrolytes

A series of polyurethanes (PUs) with different polyether soft segments [polydioxolane (PDXL), polyethylene glycol (PEG), or PDXL/PEG] were synthesized successfully, and solid polymer electrolytes based on PU/LiClO₄ complexes were prepared. The relations between structure and the ionic conductive properties of the PU‐based electrolytes were investigated by means of Fourier transform infrared spectroscopy, differential scanning calorimetry, dynamic mechanical analysis, and complex impedance analysis. Results showed that the glass‐transition temperature (T_g) of PDXL–PU was lower than that of PEG–PU. Doped lithium perchlorate (LiClO₄) salt could be dissolved well in soft segments of PDXL–PU. The ionic conductivity of the PDXL–PU/LiClO₄ complex could reach a value of 2 × 10^?5 S/cm at room temperature without the addition of an organic plasticizer. The system with PDXL/PEG as a soft segment had a higher T_g and a lower ionic conductivity than the one with PDXL as a soft segment. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 103–111, 2002     

1H NMR,thermal, and conductivity studies on PVAc based gel polymer electrolytes

The lithium‐ion conducting gel polymer electrolytes (GPE), PVAc‐DMF‐LiClO₄ of various compositions have been prepared by solution casting technique. ¹H NMR results reveal the existence of DMF in the gel polymer electrolytes at ambient temperature. Structure and surface morphology characterization have been studied by X‐ray diffraction analysis (XRD) and scanning electron microscopy (SEM) measurements. Thermal and conductivity behavior of polymer‐ and plasticizer‐salt complexes have been studied by differential scanning calorimetry (DSC), TG/DTA, and impedance spectroscopy results. XRD and SEM analyses indicate the amorphous nature of the gel polymer‐salt complex. DSC measurements show a decrease in T_g with the increase in DMF concentrations. The thermal stability of the PVAc : DMF : LiClO₄ gel polymer electrolytes has been found to be in the range of (30–60°C). The dc conductivity of gel polymer electrolytes, obtained from impedance spectra, has been found to vary between 7.6 × 10^?7 and 4.1 × 10^?4 S cm^?1 at 303 K depending on the concentration of DMF (10–20 wt %) in the polymer electrolytes. The temperature dependence of conductivity of the polymer electrolyte complexes appears to obey the VTF behavior. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008