Enhanced electrical and electrochemical properties of PMMA-clay nanocomposite gel polymer electrolytes

In the present work, effect of organically modified montmorillonite (MMT) clays on PMMA-based electrolytes has been investigated. The nanocomposites have been prepared by solution intercalation technique with varying clay loading from 0 to 5 wt.%. The formation of partially exfoliated nanocomposites has been confirmed by XRD and TEM analyses. The obtained nanocomposites were soaked with 1 M LiClO₄ in 1:1 (v/v) solution of propylene carbonate (PC) and diethyl carbonate (DEC) to get the required gel electrolytes. Surface morphology and structural conformation of the nanocomposite electrolytes have been examined by SEM and FTIR analyses, respectively. It has been observed that the ionic conductivity of the nanocomposite gel polymer electrolytes increases with the increase in clay loading and attains a maximum value of 1.3 × 10⁻³ S/cm at room temperature as revealed by ac impedance spectroscopy. Improvement of electrochemical and interfacial stabilities has also been observed in the gel electrolytes containing MMT fillers.     

New polymer electrolyte for electrochemical application

A solid polymer electrolyte consisting of poly vinylpyrrolidone (PVP) and potassium iodide (KI) were developed, characterized for possible application in dye sensitized solar cell (DSSC) as an electrolyte. Complex impedance spectroscopy revealed the enhancement in electrical conductivity (σ) by salt doping and a conductivity maximum was obtained at 30 wt% KI concentration. Dielectric phenomena also support the σ data. Fourier transform infrared spectroscopy (FTIR) confirmed the composite nature of polymer electrolyte film. Using maximum electrical conductivity film we have fabricated a DSSC which shows 0.14% efficiency at 1 sun condition.     

Structural,electrical and optical properties of pure and NaLaF<Subscript>4</Subscript> doped PEO polymer electrolyte films

A Sodium ion conducting polymer electrolyte based on Polyethylene oxide (PEO) complexed with Sodium lanthanum tetra fluoride (NaLaF₄) was prepared using solution cast technique. The complexation of the salt with PEO was confirmed by X-ray diffraction (XRD) and Fourier Transform Infrared spectroscopic (FTIR) studies. Differential Scanning Calorimetry (DSC) is carried out to determine the melting temperature of these electrolyte films. Electrical conductivity was measured in the temperature range 300–370 K as a function of dopant concentration as well as temperature. Optical absorption studies were made in the wavelength range 200–600 nm on pure and NaLaF₄ doped PEO film. The absorption edge was observed at 4.62 eV for undoped PEO while it ranged from 3.16 to 3.5 eV for NaLaF₄ doped films. The direct band gaps for undoped and NaLaF₄ doped PEO films were found to be, respectively, 4.54 and 3.44, 3.24 and 3.12 eV while the indirect band gaps were 4.43 and 3.25, 3.05 and 2.9 eV, respectively. It was found that the energy gaps and band edge values shifted to lower energies on doping with NaLaF₄ salt.     

Structure,electrical and optical properties of (PVA/LiAsF6) polymer composite electrolyte films

In this work, Li⁺ ion conducting polymer composite electrolyte films (PECs) were prepared based on poly (vinyl alcohol) (PVA), lithium hexafluoro arsenate (LiAsF₆), and ceramic filler TiO₂ using solution cast technique. The XRD and FTIR spectra were used to determine the complexation of the PVA polymer with LiAsF₆ salt. The ionic conductivities of the (PVA + LiAsF₆) and (PVA + LiAsF₆ + TiO₂) films have been determined by the A.C. impedance measurements in the temperature range 320–440 K. The maximum conductivity was found to be 5.10 × 10^?4 S cm^?1 for PVA:LiAsF₆ (75:25) + 5 wt% TiO₂ polymer composite film at 320 K. The calculation of Li⁺ ion transference number was carried out by the combination of A.C. impedance and D.C. polarization methods and is found to be 0.52 for PVA:LiAsF₆ (75:25) + 5 wt% TiO₂ film. Optical properties such as direct energy gap, indirect energy gap, and optical absorption edge values were investigated in pure PVA and salt complexed PVA films from their optical absorption spectra in the wavelength range of 200–600 nm. The absorption edge was found at 5.76 eV for undoped film, while it is observed at 4.87 and 4.70 eV for 20 and 25 wt% LiAsF₆ doped films, respectively. The direct band gaps for these undoped and salt doped PVA films were found to be 5.40, 5.12, and 4.87 eV, respectively, whereas the indirect band gaps were determined as 4.75, 4.45, and 4.30 eV. POLYM. ENG. SCI., 2010. © 2009 Society of Plastics Engineers     

Structural characterization and electrical properties of carbon nanotubes/epoxy polymer composites

The purpose of this study is to identify the relationship between the electrical and structural characteristics of multiwalled carbon nanotubes dispersed into the polymer matrix of a resin. In a first step, the composites were characterized by small‐angle neutron scattering, which provide information about the bulk dispersion of nanotubes in the matrix and form three‐dimensional networks with a surface fractal behavior. In the second step, a dielectric and electrical study was carried out in the frequency range between 1 Hz and 10 MHz at room temperature. We have found that the electric and dielectric behavior of these composites can be described by Jonscher's universal dielectric response. We show that the critical exponents describing the concentration dependence of the conductivity and the dielectric constant, obtained in the vicinity of the percolation threshold, are in good agreement with the theoretical values. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44514.     

Structural,electrical and electrochemical characterization of Ni-Pr oxide thick films

Oxides with metallic conductivity could and have been used instead of noble metals as insert electrodes in aqueous solutions as well as electrodes for high temperature fuel cells and electrolysers and as catalysts for the conversion of exhaust gases from internal combustion engines. The aim of this paper is to report the results of a physico-chemical characterization (structure, morphology, electrochemical behaviour) of Ni-Pr oxides which have been proposed as electrode materials for high temperature fuel cells.The electrochemical characterization was carried out in aqueous solutions at room temperature and with solid electrolytes at high temperature. Evidence has been found in the former case for an oxide electrode type of behaviour. In the high temperature case, very low overvoltage values have been observed during cathodic oxygen reduction, while the electrode undergoes a reaction with oxygen during anodic oxygen evolution.     

Dual functionality of PTSA as electrolyte and dopant in the electrochemical synthesis of polyaniline,and its effect on electrical properties

The electrochemical synthesis of polyaniline (PAni) powder was carried out from an aqueous solution of 0.15 mol L^?1 aniline with varying concentrations of p‐toluenesulphonic acid (PTSA) at room temperature. The PAni samples thus obtained were characterized using DC and AC conductivity, dielectric properties, infrared spectroscopy, thermogravimetric analysis, X‐ray analysis, scanning electron microscopy and ultraviolet spectroscopy. Results showed that PTSA is acting both as electrolyte and doping agent. With an increase in the PTSA concentration, there is more polaron formation, and this means an increase in charge carrier concentration and mobility. This accounts for the increase in conductivity and improved dielectric properties of the resultant PAni. The polymer was subjected to a heating and cooling cycle. The change in conductivity during the heating cycle is quite different from that during the cooling cycle, indicating some kind of hysteresis phenomenon occurring in the system. Moreover there is a net decrease in room temperature conductivity of PAni when subjected to the heating–cooling cycle. This may be due to the oxidation of PAni and generation of some kind of disorder in the structure of PAni during the heating–cooling process. Copyright © 2007 Society of Chemical Industry     

Some thermodynamic,electrical and electrochemical properties of silver vanadium bronzes

Silver vanadium bronzes (Ag_xV₂O₅) were investigated for their electrical, electrochemical and thermodynamic properties. The specific conductivity of β  Ag_xV₂O₅ as a function of temperature and composition parameter x is measured.From emf measurements values are obtained for the partial thermodynamic functions ΔH?_Ag and ΔS?_Ag for Ag_xV₂O₅ as a function of x. By aid of these values an integral curve for ΔH?_Ag and Δ?_Ag(500 K) as a function of x is constructed. It follows that silver vanadium bronzes have remarkable thermodynamic properties.Finally some current density — voltage curves are given at different temperatures for galvanic cells with a Ag_0.30V₂O₅  bronze as a cathode material.     

Enhancement of electrochemical properties of hot-pressed poly(ethylene oxide)-based nanocomposite polymer electrolyte films for all-solid-state lithium polymer batteries

PEO₁₆-LiClO₄-ZnAl₂O₄ nanocomposite polymer electrolyte (NCPE) films prepared by hot-pressing method have been investigated. In order to compare with the hot-pressed NCPEs, the NCPE films have also been prepared using the conventional solution-casting method. Field emission scanning electron microscopy (FESEM), differential scanning calorimetry (DSC), conductivity (σ) and interface property studies have been carried out on above two kinds of films. The results show that the NCPE film prepared by hot-pressing method has smoother surface, higher interface stability, lower crystallization and melting temperature values than that prepared by solution-casting method. An all-solid-state lithium polymer battery using the hot-pressed NCPE film as electrolyte, lithium metal and LiFePO₄ as anode and cathode respectively, shows high discharge specific capacity, good rate capacity, high coulombic efficiency, and excellent cycling stability as revealed by galvanostatical charge/discharge cycling tests.     

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.     

基于互穿网络技术构筑环境友好型聚合物电解质膜与电化学性能

利用互穿网络技术通过乳液聚合法制备环境友好型聚合物电解质膜,采用FTIR、XPS、SEM、TEM和TG等技术对样品结构和形貌进行表征;通过CV、EIS和充放电测试结果分析样品的电化学性能。结果表明：当m(AMPS):m(BA):m(AA):m(AN)=1:3:2:2时,互穿网络聚合物电解质膜的离子电导率为0.88mS/cm;聚合物膜的抗拉强度为7.53MPa,断裂伸长率为90.4%;聚合物膜的吸液量为150%,热收缩率为4%,表现出最佳的力学性能和电化学性能。该互穿网络聚合物电解质膜与目前锂离子电池主流的正负极材料具有较好的相容性,普适性较好。以LiCoO₂为正极,石墨为负极,0.2C倍率下,首次放电比容量分别为141.3mAh/g和347.1mAh/g,100次循环后容量保持率分别为94.8%和85.0%;2C倍率下,放电比容量为119.8mAh/g和239.0mAh/g。关键词：聚合物电解质膜;互穿网络技术;环境友好;锂离子电池     

有机无机复合固态电解质的制备及电性能研究

本文以聚环氧乙烯(PEO)为基体,添加无机固态电解质颗粒(LA),通过超声分散法制备出电化学性能优异且具有自支撑柔性的有机无机复合固态电解质膜,并组装扣式电池测试电性能,包括离子电导率、电化学窗口、锂离子迁移数及界面阻抗,得出LA对电解质膜电性能的影响.     

Mechanical,thermal, and electrical properties of metal fiber-filled polymer composites

The critical concentration at which a metal-filled composite becomes electrically conductive can be dramatically reduced by adding the metal as randomly dispersed fibers. The higher the aspect ratio of the fibers, the lower the concentration needed to induce electrical conductance. Composites exhibiting resistivities below 20 ohm-cm have been produced with less than 8 volume percent aluminum fibers, having an aspect ratio of 24:1. At low fiber loadings the tensile strength of the composites is similar to that of the unfilled polymer. The thermal properties of these composites are shown to increase monotonically in accordance with the theoretical development of Nielsen.     

Structural and electrical properties of ZnO:Ag core-shell nanoparticles synthesized by a polymer precursor method

Monodispersed core-shell type ZnO:Ag nanoparticles were synthesized by a polymer precursor method and their structural and electrical properties were reported in detail. The synthesis technique involves a sol-gel type chemical reaction between aqueous solutions of poly-vinyl alcohol (PVA), sucrose and Zn²⁺ salt. The Zn²⁺-PVA-sucrose polymer precursor powders so obtained after the reaction was further explored for the synthesis of ZnO:Ag nanoparticles. The key part of the work lies in the use of polymer coated ZnO nanoparticles as templates to obtain the ZnO core-Ag shell type nanostructures. Structural and spectroscopic analyses of the derived samples were performed with X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). The XRD patterns of the ZnO:Ag nanoparticles consist of distinct peaks corresponding to the hexagonal wurtzite type (space group P63mc) crystal structure of ZnO along with the typical peaks of face centered cubic crystal structure of metallic silver. EDS and XPS analyses confirmed the chemical composition and surface structure of the core-shell nanoparticles. Microstructural analysis revealed the monodispersed platelet shaped ZnO nanoparticles with a thin layer of Ag coating on the surface. UV–visible diffuse reflectance studies revealed the effects of Ag coating on the optical properties of the samples. Detail analysis of the dielectric properties of the samples were performed as a function of frequency (1 Hz to 10 MHz) and temperature (300–528 K) to investigate the electrical conduction mechanism in the samples.     

Development and electrochemical studies of gas diffusion electrodes for polymer electrolyte fuel cells

Electrochemical studies on low catalyst loading gas diffusion electrodes for polymer electrolyte fuel cells are reported. The best performance is obtained with an electrode formed from 20 wt% Pt/C, 0.4 mg Pt cm^–2 and 1.1 mg Nafion^® cm^–2 in the catalyst layer and 15% PTFE in a diffusion layer of 50 µm thickness, for both the cathode and the anode. However, it is also observed that the platinum requirement can be diminished to values close to 0.2 mg Pt cm^–2 in the cathode and 0.1 mg pt cm^–2 in the anode, without appreciably affecting the good characteristics of the fuel cell response. The experimental fuel cell data were analysed using theoretical models of the electrode structure and of the fuel cell system. It is seen that most of the electrode systems present limiting currents and some also show linear diffusion components arising from diffusion limitations in the gas channels and/or in the thin film of electrolyte covering the catalyst particles.     

Optical and electrical properties of a new polymer

Thin film of poly (5-isopropylidenecyclo-1,4-vinylene-2,3-dicarboxylicacidamide-s-methyl hydrazinecarbodithioate) (II) (Scheme 1) of 5 μm thickness was prepared. The dielectric properties of the prepared sample were studied as a function of frequency and temperature, and the results were analyzed by the Cole–Cole method. The optical permittivity and the dc-conductivity have been deduced, and the activation energy has been calculated and found to be 0.023 eV. Also, a detailed study of optical absorption is presented. The optical absorption spectra were measured in the wavelength range from 200–600 nm. The calculated absorption coefficient, absorption index, and determined values of energy gaps ( and ΔE) are presented. The results indicate that both mechanisms of direct and indirect transitions exist. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65:1653–1657, 1997     

Enhanced electrochemical performance of Lithium-ion batteries by conformal coating of polymer electrolyte

This work reports the conformal coating of poly(poly(ethylene glycol) methyl ether methacrylate) (P(MePEGMA)) polymer electrolyte on highly organized titania nanotubes (TiO₂nts) fabricated by electrochemical anodization of Ti foil. The conformal coating was achieved by electropolymerization using cyclic voltammetry technique. The characterization of the polymer electrolyte by proton nuclear magnetic resonance (¹H NMR) and size-exclusion chromatography (SEC) shows the formation of short polymer chains, mainly trimers. X-ray photoelectron spectroscopy (XPS) results confirm the presence of the polymer and LiTFSI salt. The galvanostatic tests at 1C show that the performance of the half cell against metallic Li foil is improved by 33% when TiO₂nts are conformally coated with the polymer electrolyte.     

Structural,electrical, and magnetic properties of Zn substituted magnesium ferrite

Zinc substituted magnesium (Mg–Zn) ferrites with the general formula Mg_1−xZn_xFe₂O₄ (x=0.00, 0.25, 0.50, 0.75, and 1.00) were prepared using the solution combustion route. The dried powder after calcination (700 °C for 2 h) was compacted and sintered at 1050 °C for 3 h. The structural, morphological, dielectric and magnetic properties of the sintered ferrites were studied using X-ray diffraction (XRD), scanning electron microscopy (SEM), impedance spectroscopy, and vibration sample magnetometry (VSM). The XRD analysis of sintered samples confirmed that the expected spinel cubic phase was formed for all samples. The crystallite sizes evaluated using Scherre's formula were found to be in the range of 47–80 nm. SEM analysis showed homogeneous grains with a polyhedral structure. The electrical conductivity increased with increasing frequency, which is normal dielectric behavior for such materials. The dielectric constant, dielectric loss tangent, and AC conductivity were found to be lowest for x=0.50. The VSM results showed that the zinc concentration had a significant influence on the saturation magnetization and coercivity.     

Hydrogen production by electrochemical decomposition of formic acid via solid polymer electrolyte

The aim of this work is to investigate the feasibility of simultaneous hydrogen production by electrochemical decomposition of formic acid via solid polymer electrolyte (SPE) in an electrochemical reactor. Titanium oxide coated with iridium oxide as anode and carbon fibre with Pt catalyst as cathode were used in the experiments.