An enhancement on electrical properties of carboxymethyl cellulose-NH4Br based biopolymer electrolytes through impedance characterization

In this work, the formulation of biopolymer electrolytes (BEs) system has been accomplished by incorporating various plasticizers with carboxymethyl cellulose–NH₄Br through solution casting technique. The ionic conductivity at room temperature of BEs system was achieved at ～10^?4 S cm^?1 with addition of 25?wt% NH₄Br and enhanced to ～10^?3 S cm^?1 when plasticizers were added. The temperature-dependence of the BEs system exhibits Arrhenius behavior. Jonschers power law was used to study the electrical properties and shows that the highest conducting BEs system can be represented by overlapping overlapping a large polaron tunneling model for poly(ethylene glycol) system a, small polaron hopping model for glycerol system, and a quantum mechanical tunneling model for ethylene carbonate system.     

Proton Conductor of Propylene Carbonate–Plasticized Carboxyl Methylcellulose–Based Solid Polymer Electrolyte

Carboxyl methylcellulose (CMC) solid polymer electrolytes were prepared by utilizing oleic acid (OA) and different wt.% of propylene carbonate (PC) by using the solution casting technique. An ionic conductivity study of the films was done by using impedance spectroscopy. The highest ionic conductivity gained is 2.52 × 10^?7 S cm^?1 at ambient temperature for sample CMC-OA-PC 10 wt.%. From transference number measurement (TNM), the value of cation diffusion coefficient, D₊, and ionic mobility, μ₊, was higher than the value of anion diffusion coefficient, D_?, and ionic mobility, μ_?. Thus, the results prove that the present samples were proton conductors.     

Proton conducting polymer blend electrolytes based on MC: FTIR,ion transport and electrochemical studies

In this work, the free-standing plasticized solid polymer electrolyte films were made utilizing methylcellulose (MC) and dextran (DN) doped with ammonium fluoride (NH₄F) and plasticized with glycerol by a typical solution casting approach. Based on the characterizations, MC-DN-NH₄F electrolyte has been shown to improve the structural, electrical, and electrochemical properties resulting from the dispersion of glycerol plasticizer. The electrochemical impedance spectroscopy (EIS) measurement for the highest inclusion of plasticizer revealed a conductivity of 2.25 × 10^-3 S/cm. The electrical equivalent circuit (EEC) model has established the circuit elements for each electrolyte. The variation trend of dielectric constant and DC conductivity was matched and confirmed by the EIS data. The fourier transform infrared (FTIR) analysis displayed credible confirmation of polymers-ion-plasticizer interactions. The dielectric study is extra highlighted the conductivity behavior. The dielectric constant and loss (ε′ and ε″) quantities were reported to be high at low frequencies. On the other hand, the irregular shape of the imaginary part of modulus (M“) spectra denotes the non-Debye behaviors of relaxation. The ion transference number (t_ion) value for the maximum plasticized system is 0.944, where the ions are the primary components for the charge transfer process. Stability of the highest conducting sample is determined to be 1.6 V, using linear sweep voltammetry (LSV).     

Investigation of the Ionic Conduction Mechanism in Carboxymethyl Cellulose/Chitosan Biopolymer Blend Electrolyte Impregnated with Ammonium Nitrate

In the present work, an attempt has been made to prepare a new natural biopolymer blend electrolyte of carboxymethyl cellulose/chitosan impregnated with NH₄NO₃ by the solution casting technique. The conductivity for the system was measured by impedance spectroscopy. The incorporation of 40 wt.% NH₄NO₃ optimized the ambient temperature conductivity of the electrolyte up to 1.03 × 10^?5 S cm^?1. All electrolytes were found to follow the Arrhenius relationship. Dielectric studies confirmed that the electrolytes obey non-Debye behavior. The temperature dependence of the power law exponent s for the highest conducting film can be represented by the correlated barrier hopping model.     

Preparation and utilization of poly(methacryloylsilatrane) as a salt‐dissociation enhancer in PEO‐based polymer electrolytes

Polymers containing silatrane units were prepared by the free radical polymerization of methacryloylsilatrane (MPS), and their conductivities were evaluated. We confirmed that MPS can be polymerized without excessive decomposition of the silatrane units by the radical polymerization initiated by azobisisobutyronitrile. The chemical structure of the polymerized MPS (pMPS) was characterized by Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, gel permeation chromatography, and matrix‐assisted laser desorption/ionization time‐of‐flight mass spectroscopy. The pMPS formed a homogeneous complex with lithium trifluoromethyl sulfonate (LiOTf), although the obtained pMPS/LiOTf complex did not show conductivity. The negligible conductivity was caused by the high glass transition temperature (T_g) of the pMPS matrix, which exceeded 70°C. The pMPS was subsequently utilized as a salt‐dissociation enhancer for the poly(ethylene oxide)‐based polymer electrolyte. MPS was copolymerized with poly[methacryloyl oligo(ethylene oxide)] (pMEO) by free radical polymerization. When the pMEO incorporated a small amount of MPS units (i.e. lower than 15 mol%), the elevation in T_g was not observed, and the conductivity markedly improved. Among the series of copolymers and when compared with pristine pMEO, the copolymer containing 6.3% of MPS units had the maximum conductivity (3.1 × 10^?4 S cm^?1 at 80°C). The Vogel–Fulcher–Tammann fitting parameters showed that the conductivity was improved by the increase in the number of carrier ions. The enhancement in salt dissociation was presumably due to the homogeneous incorporation of polar MPS units. However, when the MPS unit content exceeded 15 mol%, the conductivity was lowered because of the increase in T_g. Copyright © 2013 John Wiley & Sons, Ltd.     

Conductivity,structure, and thermal properties of chitosan‐based polymer electrolytes with nanofillers

This paper focus on the effect of nanosize (<50 nm BET) inorganic alumina (Al₂O₃) filler on the structural, conductivity, and thermal properties of chitosan‐based polymer electrolytes. Films of chitosan and its complexes were prepared using solution‐casting technique. Different amounts of Al₂O₃ viz., 3, 4.5, 6, 7.5, 9, 12, and 15 wt% were added to the highest room temperature conducting sample in the chitosan–salt system, i.e. sample containing 60 wt% chitosan–40 wt% NH₄SCN. The conductivity value of the sample is 1.29 × 10^?4 S cm^?1. On addition of 6 wt% Al₂O₃ filler the ionic conductivity increased to 5.86 × 10^?4 S cm^?1. The amide and amino peaks in the spectrum of chitosan at 1636 and 1551 cm^?1, respectively, shift to lower wavenumbers on addition of salt. The glass transition temperature T_g for the highest conducting composite is 190°C. The increase in T_g with increase in more than 6 wt% filler content is attributed to the increase in degree of crystallinity as proven from X‐ray diffraction studies. Copyright © 2009 John Wiley & Sons, Ltd.     

Enhanced electrochemical properties of a novel polyvinyl formal membrane supporting gel polymer electrolyte by Al2O3 modification

Polyvinyl formal (PVFM)‐based dense polymer membranes with nano‐Al₂O₃ doping are prepared via phase inversion method. The membranes and also their performances as gel polymer electrolytes (GPEs) for lithium ion battery are studied by field emission scanning electron microscope, X‐ray diffraction, differential scanning calorimetry, mechanical strength test, electrolyte uptake test, electrochemical impedance spectroscopy, cyclic voltammetry, and charge–discharge test. The polymer membrane with 3 wt % nano‐Al₂O₃ doping shows the improved mechanical strength of 12.16 MPa and electrolyte uptake of 431.25% compared with 10.47 MPa and 310.59% of the undoped sample, respectively. The membrane absorbs and swells liquid electrolyte to form stable GPE with ionic conductivity of 4.92 × 10^?4 S cm^?1 at room temperature, which is higher than 1.77 × 10^?4 S cm^?1 of GPE from the undoped membrane. Moreover, the Al₂O₃‐modified membrane supporting GPE exhibits wide electrochemical stability window of 1.2–4.8 V (vs. Li/Li⁺) and good compatibility with LiFePO₄ electrode, which implies Al₂O₃‐modified PVFM‐based GPE to be a promising candidate for lithium ion batteries. © 2014 Wiley Periodicals, Inc. J. Polym. Sci. Part B: Polym. Phys. 2014 , 52, 572–577     

Glycerol as an efficient plasticizer to increase the DC conductivity and improve the ion transport parameters in biopolymer based electrolytes: XRD,FTIR and EIS studies

In the current work Plasticized sodium ion conducting solid polymer electrolytes (SPEs) based on polyvinyl alcohol: methylcellulose (PVA: MC) and sodium iodide (NaI) as the electrolytic salt are fabricated. The SPE films are created using a renowned solution casting procedure, and the results of the experiments are provided. The development of polymers-salt complexes is supported by the Fourier-transform infrared transform (FTIR) analysis. The degrees of crystallinity of the polymers are noticeably decreased as a result of the glycerol plasticizer, according to X-ray diffraction test. The sample inserted with 40 wt% glycerol has the maximum ionic conductivity, according to electrical impedance spectroscopy (EIS). Electrical equivalence circuits (EEC) are used to explore the electrolytes circuit components. For the highest conducting electrolyte, the number density (n), mobility (µ), and diffusion coefficient (D) of ions are found to be 2 × 10²¹, 1.79 × 10^?6, and 4.59 × 10^?8, respectively. A high dispersion of the real component of dielectric permittivity at a lower frequency are used to infer the space charge influence induced by stainless-still (SS) electrodes. The tangent loss spectra show that the bouncing chance per unit time decreases as the glycerol concentration rises.     

Electrical Characterization and Ionic Transport Properties of Carboxyl Methylcellulose-Oleic Acid Solid Polymer Electrolytes

Electrical impedance spectroscopy was used to measure the conductivity of solid polymer electrolytes. From the impedance study, the highest ionic conductivity of solid polymer electrolytes based on carboxyl methylcellulose as polymer host and oleic acid as the doping salt, prepared by the solution casting method at room temperature, σ_r.t, is 2.11 × 10^?5 S cm^?1 for the sample containing 20 wt.% of oleic acid. Transference number measurement was performed to correlate the diffusion phenomena to the conductivity behavior of carboxyl methylcellulose-oleic acid solid polymer electrolytes. From the transference number measurement study, the conduction species carrier of the cation (+) is higher than that of the anion (?). Thus, the results proved that the samples are proton-conducting solid polymer electrolytes.     

Polyacrylonitrile–lithium bis(oxalato) borate polymer electrolyte for electrical double layer capacitors

Lithium ion conducting polymer electrolytes based on polyacrylonitrile (PAN) and lithium bis(oxalato)borate (LiBOB) have been prepared and characterized. The polymer electrolytes having PAN:LiBOB weight ratios of 90:10, 80:20, 70:30, 60:40 and 50:50 were prepared using dimethylformamide as solvent. The electrolyte having the composition 50 wt.% PAN–50 wt.% LiBOB shows the highest room temperature conductivity of 2.55 × 10^?5 S cm^?1. This sample demonstrated a lithium ion transference number of 0.25 and a breakdown voltage of 1.6 V. The highest conducting electrolyte was then sandwiched between two symmetrical carbon electrodes to fabricate an electrical double layer capacitor (EDLC). The EDLCs were characterized using impedance measurement, cyclic voltammetry (CV) and galvanostatic charge–discharge tests. The capacitance obtained from impedance measurement is about 35 F g^?1 at frequency 10 mHz. From CV, the capacitance is calculated to be 24 F g^?1 at 10 mV s^?1 scan rate. The discharge capacitance of the EDLCs is determined in the range from 22 to 10 F g^?1 at corresponding discharge currents from 0.2 to 1.5 mA, respectively. This also corresponds to a specific energy from 3.01 to 1.47 W h kg^?1 and a specific power from 380 to 474 W kg^?1, respectively. Copyright © 2013 John Wiley & Sons, Ltd.     

HPLC Method for the Determination of the Purity of K[Pt(NH3)Cl3], a Precursor of the Platinum Complexes with Cytostatic Activity

K[Pt(NH₃)Cl₃], a valuable precursor for the preparation of platinum complexes with cytostatic activity, e.g. satraplatin, picoplatin, LA-12 and cycloplatam, is currently prepared from cis-[Pt(NH₃)₂Cl₂] or K₂[PtCl₄] and these are the usual impurities in the final product. A simple, selective and sensitive HPLC-UV analytical method for the determination of the purity of K[Pt(NH₃)Cl₃] and the quantification of the impurities has been developed and validated. The platinum complexes present in the final product were separated on a strong base ion exchange column by the gradient elution with detection at 213 nm. Intra-assay precisions for the platinum complexes respective to their ions ([PtCl₄]^2?, [Pt(NH₃)Cl₃]^? and cis-[Pt(NH₃)₂Cl₂]) were between 0.1 and 2.0% (relative standard deviation); intermediate precisions were between 1.4 and 2.0% and accuracies were between 98.6 and 101.4%. Limits of detection of [PtCl₄]^2?, [Pt(NH₃)Cl₃]^? and cis-[Pt(NH₃)₂Cl₂] were 6 µg · ml^?1, 13 mg · ml^?1 and 5 µg · ml^?1 respectively, limits of quantification of [PtCl₄]^2?, [Pt(NH₃)Cl₃]^? and cis-[Pt(NH₃)₂Cl₂] were 51 µg · ml^?1, 55 mg · ml^?1 and 20 µg · ml^?1 respectively.     

Correlation between the structural,electrical and electrochemical performance of layered Li(Ni<Subscript>0.33</Subscript>Co<Subscript>0.33</Subscript>Mn<Subscript>0.33</Subscript>)O<Subscript>2</Subscript> for lithium ion battery

The Li(Ni_0.33Co_0.33Mn_0.33)O₂ (LNCMO) cathode material is prepared by poly(vinyl pyrrolidone) (PVP)-assisted sol-gel/hydrothermal and poly(ethylene glycol)-block-poly(propylene glycol)-block-poly (ethylene glycol) (Pluronic-P123)-assisted hydrothermal methods. The compound prepared by PVP-assisted hydrothermal method shows a comparatively higher electrical conductivity of ~2?×?10^?5 S cm^?1 and exhibits a discharge capacity of 152 mAh g^?1 in the voltage range of 2.5 to 4.4 V, for a C-rate of 0.2 C, whereas the compounds prepared by P123-assisted hydrothermal method and PVP-assisted sol-gel method show a total electrical conductivity in the order of 10^?6 S cm^?1 and result in poor electrochemical performance. The structural and electrical properties of LNCMO (active material) and its electrochemical performance are correlated. The difference in percentage of ionic and electronic conductivity contribution to the total electrical conductivity is compared by transference number studies. The cation disorder is found to be the limiting factor for the lithium ion diffusion as determined from ionic conductivity values.     

Determination of Bromide,Chloride, and Fluoride in Cigarette Tobacco by Ion Chromatography after Microwave-Induced Combustion

A microwave-induced combustion (MIC) method was applied for cigarette tobacco digestion and further determination of bromide (Br), chloride (Cl), and fluoride (F) by ion chromatography (IC). Samples (up to 500 mg) were combusted at 20 bar of oxygen. Combustion was complete in less than 30 s, and analytes were absorbed in (NH₄)₂CO₃ solutions. A reflux step, not available in other systems, was applied to improve analyte absorption. Absorbing solution with 50 mmol L^?1(NH₄)₂CO₃ was selected because it showed recovery close to 100% for samples containing spikes of halogens. Accuracy of the proposed procedure was evaluated by analysis of certified reference materials and the agreement was better than 97% for all analytes using 50 mmol L^?1 (NH₄)₂CO₃ as absorbing solution and 5 min of reflux. Temperature during combustion was higher than 1400°C and the residual carbon content was always lower than 1%. With the use of the MIC system, up to eight samples could be processed simultaneously, and a single absorbing solution was suitable for all analytes. Limits of quantification by MIC and further IC determination were 0.50, 0.20, and 0.10 µg g^?1 for Br, Cl, and F, respectively.     

Octahedral copper(II) carboxylate complex: synthesis,structural description,DNA-binding and anti-bacterial studies

Self-assembly of CuSO₄, para-methyl-2-phenyl acetate and 1,10-phenanthroline afforded good-quality crystalline complex in quantitative yield. The complex was characterized by FTIR and UV-visible spectroscopy, electrochemistry, and powder and single-crystal XRD studies. Its structure was found to possess axially elongated octahedral symmetry with CuO₄N₂ chromophore. Its purity was assessed by powder XRD spectrum. Absorption study yielded a broad band corresponding to ²E_g→²T_2 g transition. Electrochemical solution study indicated diffusion-controlled irreversible electron transfer process corresponding to Cu(II)/Cu(I) redox couple with diffusion coefficient = 7.89(±0.1)×10^?9 cm²s^?1. Results of spectroscopic techniques support each other. Complex exhibited excellent DNA-binding ability through UV-visible spectroscopy and cyclic voltammetry yielding K_b values 1.399 × 10⁴ M^?1 and 5.81 × 10³ M^?1, respectively. The complex exhibited significant activity against bacterial strains Escherichia coli, Micrococcus luteus and Staphylococcus aureus and good activity against Bacillus subtilis. These preliminary studies impart good biological relevance on the synthesized complex.     

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.     

Thermoelectric behavior of organic thin film nanocomposites

Organic thin film nanocomposites, prepared by liquid‐phase exfoliation, were investigated for their superior electrical properties and thermoelectric behavior. Single‐walled carbon nanotubes (SWNT) were stabilized by intrinsically conductive poly(3,4‐ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) in an aqueous solution. The electrical conductivity (σ) was found to increase linearly as 20 to 95 wt % SWNT. At 95 wt % SWNT, these thin films exhibit metallic electrical conductivity (～4.0 × 10⁵ S m^?1) that is among the highest values ever reported for a free‐standing, fully organic material. The thermopower (S) remains relatively unaltered as the electrical conductivity increases, leading to a maximum power factor (S²σ) of 140 μW m^?1 K^?2. This power factor is within an order of magnitude of bismuth telluride, so it is believed that these flexible films could be used for some unique thermoelectric applications requiring mechanical flexibility and printability. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2013     

Preparation and characterization of conductive chitosan–ionic liquid composite membranes

Anhydrous conductive membranes composing of a composite of chitosan (CS) and ionic liquids with symmetrical carboxyl groups were explored. Scanning electron microscope images revealed that porous composite membranes could be obtained by combining CS with different amounts of 1,4‐bis(3‐carboxymethyl‐imidazolium)‐1‐yl butane chloride ([CBIm]Cl). Fourier transform infrared and proton nuclear magnetic resonance confirmed that the formation of ammonium salts after CS was combined with [CBIm]Cl. The thermal property of CS–ionic liquid composite membranes was studied through thermogravimetric analysis. The anhydrous ionic conductivities of CS–[CBIm]X (X = Cl, Ac, BF₄, and I) composite membranes were measured using ac impedance spectroscopy at room temperature in N₂ atmosphere. The conductivities (0.4–0.7 × 10^?4 Scm^?1), found to be in the same range as semiconductors, were significantly higher than those of pure CS membrane (<10^?8 Scm^?1). In addition, the anhydrous conductivity of composite membrane based on CS–[CBIm]I at room temperature reached a level as high as 0.91 × 10^?2 Scm^?1 when iodine was doped. Copyright © 2011 John Wiley & Sons, Ltd.     

Li1.3Al0.3Ti1.7(PO4)3 filler effect on (PEO)LiClO4 solid polymer electrolyte

Composite polymer electrolyte (CPE) films consisting of PEO, LiClO₄, and Li_1.3Al_0.3Ti_1.7(PO₄)₃ with fixed EO/Li = 8 but different relative compositions of the two lithium salts were prepared by the solution casting method. The CPE films were characterized using SEM, DSC, electrical impedance spectroscopy (EIS), and ion transference number measurement. It was found that the incorporation of LiClO₄ and Li_1.3Al_0.3Ti_1.7(PO₄)₃ into PEO by keeping EO/Li = 8 reduced the crystallinity of PEO from 50.34% to the range of 3.57–15.63% depending upon the relative composition of the two salts. The room temperature impedance spectra of the CPE films all exhibited a shape of depressed semicircle in the high frequency range and inclined line in the low frequency range, but the high temperature ones were mainly inclined lines. The Li⁺ ionic conductivity of the CPE films mildly increased and then decreased with increasing Li_1.3Al_0.3Ti_1.7(PO₄)₃ content, and the maximum conductivities were obtained at Li_1.3Al_0.3Ti_1.7(PO₄)₃ content of 15 wt % for all measuring temperatures, for example, 1.378 × 10^?3 S/cm at 100 °C and 1.387 × 10^?5 S/cm at 25 °C. The temperature dependence of the ionic conductivity of the CPE films follows the Vogel–Tamman–Fulcher (VTF) equation The pseudo activation energies (E_a) were rather low, 0.053–0.062 eV, indicating an easy migration of Li⁺ in the amorphous phase dominant PEO. The pre‐exponent constant A and ion transference number t_Li+ were found to have a similar variation tendency with increasing Li_1.3Al_0.3Ti_1.7(PO₄)₃ content and reached their maximums also at Li_1.3Al_0.3Ti_1.7(PO₄)₃ content of 15 wt %. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 743–751, 2005     

Study of CO2 adsorption in functionalized carbon

We evaluated the ability of CO₂ adsorption in functionalized activated carbons granular and monolithic type, obtained by chemical activation of African palm stone with H₃PO₄ and CaCl₂. We made a comparison between two methods of incorporation of nitrogen groups: the impregnation method with NH₄OH solution and NH₃ gasification. The materials were texturally characterized by N₂ adsorption at 77 K, the isotherms shows obtaining microporous materials with surface areas between 545–1425 m²?g^?1 and pore volumes between 0.22 to 0.53 cm³?g^?1. It was established that with the methodologies used for functionalization is increased content of nitrogen groups, was achieved a higher proportion of such groups when carrying out the process in liquid phase with NH₄OH. The incorporation of nitrogen groups in the material generates an increase of up to 65 % in the CO₂ adsorption capacity of the MCa2 (Monolith prepared with CaCl₂ solution at 2 %) sample. Was reached a maximum adsorption capacity of 344 mgCO²?g^?1 in the MCa2FAL (sample MCa2 functionalized with NH₄OH solution) sample.     

π‐Complexes of Copper(I) with Terminal Alkynes. Synthesis and Crystal Structure of [(HC≡CCH2NH3)(Cu2Br3)] π‐Complex

Crystals of the zwitterionic copper(I) π‐complex [(HC≡CCH₂NH₃)Cu₂Br₃] have been synthesized by interaction of CuBr with [HC≡CCH₂NH₃]Br in aqueous solution (pH < 1) and X‐ray studied. The crystals are monoclinic: space group P2₁/n, a = 6.722(4), b = 12.818(8), c = 9.907(3) Å, β = 100.25(4)°, V = 840.0(8) ų, Z = 4, R = 0.0592 for 3015 reflections. The crystal structure of the π‐complex contains isolated [(HC≡CCH₂NH₃)⁺(Cu₂Br₃)^?]₂ units which are incorporated into a framework by strong hydrogen N–H···Br and C≡C–H···Br bonds. The length of π‐coordinated propargylammonium C≡C bond is equal 1.216(8) Å and Cu(I)–(C≡C) distance equals 1.958(5) Å.