Characteristics of proton conducting polymer electrolyte based on chitosan acetate complexed with CH3COONH4

The polymer electrolytes based on chitosan and ammonium acetate (CH₃COONH₄) were prepared by solution casting technique and the properties were studied. With the addition of CH₃COONH₄, the amorphous nature of the polymer electrolytes was promoted. The glass transition temperature, activation energy, and conductivity are closely related. Lower the glass transition temperature, lower the activation energy, higher the conductivity. The 40 wt % ammonium acetate doped polymer electrolyte has the lowest glass transition temperature of 369 K, the lowest activation energy of 0.19 eV, and the highest ionic conductivity of 2.87 × 10^?4 S cm^?1 at room temperature. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 549–554, 2009     

Low glass transition temperature polymer electrolyte prepared from ionic liquid grafted polyethylene oxide

In this contribution, we report a new type of poly (ionic liquids) prepared by imidazolium ionic liquids directly grafting onto polyethylene oxide backbone. Different molecular weights of poly (ionic liquids) are obtained with a low glass transition temperature up to ?14 °C. The materials as polymer electrolyte achieve a high conductivity around 10^?5 S cm^?1 at 30 °C and close to 10^?3 S cm^?1 at 90 °C. High viscosity up to 4000 Pa s at room temperature would minimize the electrolytes leaking in electrochemical devices. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2104–2110     

The structure and electric characters of proton‐conducting chitosan membranes with various ammonium salts as complexant

The structural and electric properties of chitosan electrolytes doped by three different ammonium salts [CH₃COONH₄, NH₄Cl, and (NH₄)₂SO₄] were discussed. The chitosan electrolytes were prepared by solution casting technique. The results show that the addition of ammonium salts leads to: The formation of complexation between ammonium salts and chitosan matrix, the destruction of crystal forms, and the enhancement of amorphous nature. With the rise of salt content, both the glass transition temperature and the activation energy show a “V”‐type trend, whereas the conductivity exhibits a reverse trend. For different ammonium salts, the electric properties of the chitosan electrolyte are different due to the Coulomb force between anion of salts and functional groups. The CH₃COONH₄ doped chitosan electrolyte exhibits the optimum electric properties, whereas those of (NH₄)₂SO₄ doped chitosan electrolyte are worst. The chitosan electrolyte doped with 40 wt % CH₃COONH₄ has the lowest glass transition temperature of 369 K, the lowest activation energy of 0.19 eV, and the highest ionic conductivity of 2.87 × 10^?4 S cm^?1 at room temperature. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 880–885, 2010     

Conductivity and thermal behavior of proton conducting polymer electrolyte based on poly (N-vinyl pyrrolidone)

The polymer electrolytes based on poly N-vinyl pyrrolidone (PVP) and ammonium thiocyanate (NH₄SCN) with different compositions have been prepared by solution casting technique. The amorphous nature of the polymer electrolytes has been confirmed by XRD analysis. The shift in T_g values and the melting temperatures of the PVP-NH₄SCN electrolytes shown by DSC thermo-grams indicate an interaction between the polymer and the salt. The dependence of T_g and conductivity upon salt concentration have been discussed. The conductivity analysis shows that the 20 mol% ammonium thiocyanate doped polymer electrolyte exhibit high ionic conductivity and it has been found to be 1.7 × 10⁻⁴ S cm⁻¹, at room temperature. The conductivity values follow the Arrhenius equation and the activation energy for 20 mol% ammonium thiocyanate doped polymer electrolyte has been found to be 0.52 eV.     

Solid polymer electrolytes III: Preparation,characterization, and ionic conductivity of new gelled polymer electrolytes based on segmented,perfluoropolyether‐modified polyurethane

New segmented polyurethanes with perfluoropolyether (PFPE) and poly(ethylene oxide) blocks were synthesized from a fluorinated macrodiol mixed with poly(ethylene glycol) (PEG) in different ratios as a soft segment, 2,4‐toluene diisocyanate as a hard segment, and ethylene glycol as a chain extender. Fourier transform infrared, NMR, and thermal analysis [differential scanning calorimetry and thermogravimetric analysis (TGA)] were used to characterize the structures of these copolymers. The copolymer films were immersed in a liquid electrolyte (1 M LiClO₄/propylene carbonate) to form gel‐type electrolytes. The ionic conductivities of these polymer electrolytes were investigated through changes in the copolymer composition and content of the liquid electrolyte. The relative molar ratio of PFPE and PEG in the copolymer played an important role in the conductivity and the capacity to retain the liquid electrolyte solution. The copolymer with a 50/50 PFPE/PEG ratio, having the lowest decomposition temperature shown by TGA, exhibited the highest ionic conductivity and lowest activation energy for ion transportation. The conductivities of these systems were about 10^?3 S cm^?1 at room temperature and 10^?2 S cm^?1 at 70 °C; the films immersed in the liquid electrolyte with an increase of 70 wt % were homogenous with good mechanical properties. © 2002 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 486–495, 2002; DOI 10.1002/pola.10119     

Synthesis and characterization of polymer electrolytes based on cross‐linked phenoxy‐containing polyphosphazenes

A new method to prepare the polymer electrolytes for lithium‐ion batteries is proposed. The polymer electrolytes were prepared by reacting poly(phosphazene)s (MEEPP) having 2‐(2‐methoxyethoxy)ethoxy and 2‐(phenoxy)ethoxy units with 2,4,6‐tris[bis(methoxymethyl)amino]‐1,3,5‐triazine (CYMEL) as a cross‐linking agent. This method is simple and reliable for controlling the cross‐linking extent, thereby providing a straightforward way to produce a flexible polymer electrolyte membrane. The 6 mol % cross‐linked polymer electrolyte (ethylene oxide unit (EO)/Li = 24:1) exhibited a maximum ionic conductivity of 5.36 × 10^?5 S cm^?1 at 100 °C. The ⁷Li linewidths of solid‐state static NMR showed that the ionic conductivity was strongly related to polymer segment motion. Moreover, the electrochemical stability of the MEEPP polymer electrolytes increased with an increasing extent of cross‐linking, the highest oxidation voltage of which reached as high as 7.0 V. Moreover, phenoxy‐containing polyphosphazenes are very useful model polymers to study the relationship between the polymer flexibility; that is, the cross‐linking extent and the mobility of metal ions. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 352–358     

Conductivity and Dielectric Behavior Studies of Carboxymethyl Cellulose from Kenaf Bast Fiber Incorporated with Ammonium Acetate-BMATFSI Biopolymer Electrolytes

This work was undertaken to study the conductivity and dielectric behavior of a biopolymer electrolyte based on carboxymethyl cellulose that was synthesized from kenaf fiber. Biopolymer electrolytes comprised of various weight percentage ratios of the host polymer, ammonium acetate salt, and butyl-trimethyl ammonium bis(trifluoromethylsulfonyl)imide ionic liquid were prepared by the solution casting technique. The conductivity values were determined by impedance spectroscopy. The highest conductivity found was 2.18 × 10^?3 S cm^?1 at ambient temperature for the film incorporated with 20 wt.% salt and 20 wt.% ionic liquid. In order to understand the conductivity behavior, a dielectric study was carried out. The results showed that the system obeys the Arrhenius rule and confirmed non-Debye behavior in the sample.     

High ionic conductivity of all-solid polymer electrolytes based on polyorganophosphazenes

A series of all-solid polymer electrolytes were prepared by cross-linking new designed poly(organophosphazene) macromonomers. The ionic conductivities of these all-solid, dimensional steady polymer electrolytes were reported. The temperature dependence of ionic conductivity of the all-solid polymer electrolytes suggested that the ionic transport is correlated with the segmental motion of the polymer. The relationship between lithium salts content and ionic conductivity was discussed and investigated by Infrared spectrum. Furthermore, the polarity of the host materials was thought to be a key to the ionic conductivity of polymer electrolyte. The all-solid polymer electrolytes based on these poly(organophosphazenes) showed ionic conductivity of 10⁻⁴ S cm⁻¹ at room temperature.     

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.     

Proton-conducting membranes: poly (N-vinyl pyrrolidone) complexes with various ammonium salts

The present study focuses on the proton-conducting polymer electrolytes; poly (N-vinyl pyrrolidone)–ammonium thiocyanate and poly (N-vinyl pyrrolidone)–ammonium acetate prepared by solution casting technique. The XRD analysis indicates the amorphous nature of the polymer electrolytes. The Raman spectra of the C=O vibration of pure polymer PVP at 1,663 cm^?1 has been appeared as doublet in the polymer electrolytes. The introduction of this new peak in the salt-doped polymer electrolytes may be due to interaction of the cation with the polymer. The room temperature ionic conductivity σ _303κ has been found to be high, 1.7?×?10^?4 S cm^?1 for 80 mol% PVP–20 mol% NH₄SCN and 1.5?×?10^?6 S cm^?1 for 75 mol% PVP–25 mol% CH₃COONH₄. The polymer electrolytes have been tested for their application in Zn–air battery.     

Cross-linking copolymers of acrylates’ gel electrolytes with high conductivity for lithium-ion batteries

The cross-linking gel copolymer electrolytes containing alkyl acrylates, triethylene glycol dimethacrylate, and liquid electrolyte were prepared by in situ thermal polymerization. The gel polymer electrolytes containing 15 wt% polymer content and 85 wt% liquid electrolyte content with sufficient mechanical strength showed the high ionic conductivity around 5?×?10^?3 Scm^?1 at room temperature. The gel electrolytes containing different polymer matrices were prepared, and their physical observation and conductivity were discussed carefully. The cross-linking copolymer gel electrolytes of alkyl acrylates with other monomers were designed and synthesized. The results showed that copolymerization can improve the mechanical properties and ionic conductivities of the gel electrolytes. The polymer matrices of gels had excellent thermal stability and electrochemical stability. The scanning electron microscope analysis showed the gel electrolyte was the homogeneous structure, and the cross-linking polymer host was the porous three-dimensional network structure, which demonstrated the high conductivity of the gel electrolytes. The gel polymer Li-ion battery was prepared by this in situ thermal polymerization. The cell exhibited high charge-discharge efficiency at 0.1 C. The results of LiFePO4-PEA-Li cell and graphite-PEA-Li cell showed that gel polymer electrolytes have good compatibility with the battery electrodes materials.     

Synthesis and ionic conductivity of hyperbranched poly(glycidol)

A novel hyperbranched poly(glycidol) (HPG) was prepared and characterized. The synthesized HPG was used as a substrate of a polymer electrolyte. The ionic conductivity of a blend of HPG, polyurethane (PU), and salt was studied. The ionic conductivity of HPG/PU/LiClO₄ was about 6.6 × 10^?6 S · cm^?1 at 20 °C and 6.3 × 10^?4 S · cm^?1 at 60 °C. The results indicated that HPG showed higher solubility for salt than linear polyether when both had the same [O]/[Li⁺] molar ratio. The main reason was that more cavities and a lower degree of chain entanglement in HPG resulted in a lower glass‐transition temperature and were beneficial for decreasing the aggregation of salt or enhancing the ionic conductivity. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 2225–2230, 2001     

Effect of ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide on the properties of poly(glycidyl methacrylate) based solid polymer electrolytes

A free standing polymer electrolytes films, containing poly(glycidyl methacrylate) (PGMA) as the polymer host, lithium perchlorate (LiClO₄), and ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl) imide [Bmim][TFSI] as a plasticizer was successfully prepared via the solution casting method. The XRD analysis revealed the amorphous nature of the electrolyte. ATR-FTIR and thermal studies confirmed the interaction and complexation between the polymer host and the ionic liquid. The maximum ionic conductivity of the solid polymer electrolyte was found at 2.56 × 10^–5 S cm^–1 by the addition of 60 wt % [Bmim][TFSI] at room temperature and increased up to 3.19 × 10^–4 S cm^–1 at 373 K, as well as exhibited a transition of temperature dependence of conductivity: Arrhenius-like behavior at low and high temperatures.     

Ionic conductivity probed in main chain liquid crystalline azobenzene polyesters

Three main chain thermotropic liquid crystalline (LC) azobenzene polymers were synthesized using the azobenzene twin molecule (P4P) having the structure Phenylazobenzene‐tetraethyleneglycol‐Phenylazobenzene as the AA monomer and diols like diethylene glycol, tetraethylene glycol (TEG), and hexaethylene glycol as the BB comonomer. Terminal ? C(O)OMe units on P4P facilitated transesterification with diols to form polyesters. All polymers exhibited stable smectic mesophases. One of the polymers, Poly(P4PTEG) was chosen to prepare composite polymer electrolytes with LiCF₃SO₃ and ionic conductivity was measured by ac impedance spectroscopy. The polymer/0.3 Li salt complex exhibited a maximum ionic conductivity in the range of 10^?5 S cm^?1 at room temperature (25 °C), which increased to 10^?4 S cm^?1 above 65 °C. The temperature dependence of ionic conductivity was compared with the phase transitions occurring in the sample and it was observed that the glass transition had a higher influence on the ionic conductivity compared to the ordered LC phase. Reversible ionic conductivity switching was observed upon irradiation of the polymer/0.3 Li salt complex with alternate UV and visible irradiation. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 629–641     

Employment of [Amim] Cl in the effort to upgrade the properties of cellulose acetate based polymer electrolytes

Transparent thin film polymer electrolytes were prepared by solvent casting technique with the doping of environmental-friendly ionic liquid, 1-allyl-3-methylimidazolium chloride ([Amim] Cl) into the matrix formed by cellulose acetate (CA) and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI). The ionic conducting nature of this system improves significantly from the order of 10^?7–10^?2 S cm^?1 upon increasing doping of [Amim] Cl content till a maximum of 4.68 × 10^?2 S cm^?1 is attained for the composition CA:LiTFSI:[Amim] Cl (14:6:80 wt%). The improving trend in ionic conductivity results from the bond weakening between the connecting atoms in the crystalline region that induces to the increase in amorphous counterpart fractions in the CA matrix. This observation was proved via the accountancies in the reduction of relative viscosity, root mean square value and increase in void as increase in [Amim] Cl doping. The resultant phase conversion hence permits immense lithium ion (Li⁺) fluidity along the polymer backbone and assisting the improvement in ionic conductivity. The thin film polymer electrolyte is found to be elastic in the presence of crystalline fraction and radically deforms upon the chains diffusion into the amorphous fraction. The linear curvatures of the Arrhenius plot justify the conductivity improvement as via the increasing frequency of Li⁺ ions hopping as the temperature increases. The increasing addition of [Amim] Cl diminishes both the heat-resistivity and thermal stability of CA:LiTFSI:[Amim] Cl matrix.     

Effect of solvents on properties of polymer gel-electrolyte based on polyester diacrylate

New polymer gel electrolytes based on polyester diacrylates and LiClO₄ salt solutions in organic solvents are developed for lithium ion and lithium polymer batteries with a high ionic conductivity up to 2.7 × 10^?3 Ohm^?1cm^?1 at the room temperature. To choose the optimum liquid electrolyte composition, the dependence is studied of physico-chemical parameters of new gel electrolytes on the composition of the mixture of aprotic organic solvents: ethylene carbonate, propylene carbonate, and λ-butyrolacton. The bulk conductivity of gel electrolytes and exchange currents at the gel electrolyte/Li interface are studied using the electrochemical impedance method in symmetrical cells with two Li electrodes. The glass transition temperature and gel homogeneity are determined using the method of differential scanning calorimetry. It is found that the optimum mixture is that of propylene carbonate and λ-butyrolacton, in which a homogeneous polymer gel is formed in a wide temperature range of ?150 to +50°C.     

Gel polymer electrolytes prepared with porous membranes based on an acrylonitrile/methyl methacrylate copolymer

Porous membranes based on acrylonitrile/methyl methacrylate copolymer were prepared by a phase‐inversion method. Microstructures of the porous membranes were controlled through the variation of the evaporation drying time before immersion in a nonsolvent bath. Gel polymer electrolytes were prepared from these porous membranes via soaking in an organic electrolyte solution. They encapsulated the electrolyte solution well without solvent leakage and maintained good mechanical properties that allowed the preparation of thin films (～23 μm). These systems showed acceptable ionic conductivity values (>6.0 × 10^?4 S/cm) at room temperature and sufficient electrochemical stability over 4.4 V that allowed applications in lithium‐ion polymer batteries. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1496–1502, 2002     

Tough Gel Electrolyte Using Double Polymer Network Design for the Safe,Stable Cycling of Lithium Metal Anode

The growth of lithium dendrites and low coulombic efficiency restrict the development of Li metal anodes. Polymer electrolytes are expected to be promising candidates to solve the issue, but ways to obtain a polymer electrolyte that integrates high ionic conductivity and high mechanical toughness is still challenging. By introducing a double polymer network into the electrolyte design to reshape it, a tough polymer electrolyte was developed with high conductivity, and stable operation of lithium metal anodes was further realized. The double network (DNW) gel electrolyte has high modulus of 44.3 MPa and high fracture energy of 69.5 kJ m^?2. The conductivity of DNW gel is 0.81 mS cm^?1 at 30 °C. By using this gel electrolyte design, the lithium metal electrode could be cycled more than 400 times with a coulombic efficiency (CE) as high as 96.3 % with carbonate‐based electrolytes.     

Boron-incorporated Sulfonated polysulfone/polyphosphoric acid electrolytes for supercapacitor application

In the present work, boron-doped multicomponent gel polymer electrolytes composed of host polymer, sulfonated polysulfone (SPSU) and the additives; ionic liquid, 1-ethyl-3-methyl-imidazolium tetrafluoroborate (IL), H₃BO₃, polyphosphoric acid (PPA) were prepared. Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA) techniques were used to characterize the sulfonated polysulfone-based electrolytes. Ion conductivity of these gel electrolytes were studied by dielectric impedance analyzer within the temperature from ?20 to 100°C. The ionic conductivity of the SPSU-5IL-1PPA and SPSU-5IL-1H₃BO₃-1PPA were measured as 4.8 × 10^?3 and 9 × 10^?4 S cm^?1, respectively. Supercapacitor having activated carbon-based composite electrode and electrolyte was constructed with the configuration: Al/C/electrolyte/C/Al. The electrochemical properties and ion transfer characteristics of the supercapacitor were investigated by the cyclic voltammetry (CV). Galvanostatic charge—discharge experiments exhibited good electrochemical reversibility and produced a specific capacitance value of 120 F g^?1 at 1 A g^?1. The symmetric supercapacitor system was retained almost 85% of its initial activity after 1000 cycle.     

Ionic conductivity of multiarm star polymer/LiClO4 electrolytes

A series of polymer electrolytes based on multiarm polymers and lithium salt complexes were characterized by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and impedance measurement. The relationships of conductivity with salt concentration, temperature, and arm numbers are discussed. It is suggested that the star polymer has a higher solvency and ion transfer ability on lithium salts than on linear polymers. The conductivity maximum appeared at a higher salt concentration ([EO]/[Li] = 4). Impedance measurement suggested that the optimum conductivity was 2 × 10^?4 s · cm^?1. The conductivity increased with temperature and the dependence of ionic conductivity on temperature fits the Arrhenius equation. Among the studied systems, the star polymer with a five arm number performs better than other structures. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 4195–4198, 2004