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).     

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.     

Structural,morphological, optical and dielectric properties of M3+/PVA/PEG SPE Films (M = La,Y, Fe or Ir)

Low band gap polymer complexes are promising due to its flexibility, and exhibiting electronic and optical properties of inorganic semiconductors. The effect of PEG on the physical properties of PVA was evaluated. Then, blend (PVA: PEG = 50:50) doped with rare earth (La or Y) and transition metal (Fe or Ir) chlorides to obtain solid polymer electrolyte films. XRD shows that adding PEG to PVA results in a new peak, 2θ = 23^o with increased intensity as PEG ratio increases. However, doping with La³⁺, Fe³⁺ or Ir³⁺ eliminate this peak and decrease the crystallinity. SEM exhibits significant changes in the morphology of films. FTIR confirms miscibility between PVA & PEG and the complexation of the salts. The optical band gap (E_g) of PVA ~ 5.37 eV, decreased slightly by blending with PEG. While it decreased significantly to 2.64 eV and 2.78 eV after doping with Fe³⁺ or Ir³⁺. There are a consistency between E_g values obtained by Tauc's model and that obtained from the optical dielectric loss. The dielectric constant and loss, in temperature range 303–405 K & frequency range 1.0 kHz ‐ 5.0 MHz, indicate one or two relaxation peak(s) depending on the film composition. Accordingly, conduction mechanism varied between correlated barrier hopping and large polaron tunneling. The DC conductivity was strongly depend on the dielectric loss. The transition metal salts appear to be more effective than the rare earth ones in increasing σ_ac of films to higher values that candidates them in semiconductors industry.     

Effect of polyoxomolybdate nanocluster doping on the dielectric characteristics of polyvinyl alcohol nanocomposite films

Electrophysical parameters of polyvinyl alcohol (PVA) films comprising nanocluster molybdenum-based polyoxometalates (POMs), namely electrical conductivity, dielectric loss tangent, and dielectric permittivity, have been studied. Frequency and concentration curves have been plotted for these properties, which characterize the relaxation parameters of polymeric macromolecules and interactions of the polymer with spheroidal Keplerate POMs (Mo₁₃₂ and Mo₇₂Fe₃₀) and toroidal POMs (Mo₁₃₈).     

Effect of polyaniline (PANI) on Poly(vinylidene fluoride-co-hexaflouro propylene) (PVDF-co-HFP) polymer electrolyte membrane prepared by breath figure method

Poly(vinylidene fluoride-co-hexaflouro propylene) is a well-known material for polymer electrolyte membranes (PEMs) due to its low cost, high mechanical integrity and excellent chemical resistance; however, its pure form has limited characteristics that require further modification to achieve optimum results. Therefore, the different dosages of polyaniline (PANI) (10 wt%, 20 wt%, 30 wt%, 40 wt% and 50 wt%) were incorporated into PVDF-HFP blend to fabricate PVDF-HFP/PANI polymer electrolyte membrane by using breath-figure method. The FTIR peaks of PVDF-HFP and PVDF-HFP/PANI membrane confirms the successful incorporation of PANI into PVDF-HFP blend, while TGA, DSC and XRD analysis shows the PANI effect on stability and ionic conductivity of PVDF-HFP membrane. The PVDF-HFP/PANI membrane with 30 wt% PANI found superior with the highest porosity of 83%, electrolyte uptake of 270% and ionic conductivity of 1.96 mS cm⁻¹; however, the other concentrations of PANI were also effective and enhanced the performance of PVDF-HFP membrane. This shows the improved performances of PVDF-HFP membrane were attributed to successful incorporation of PANI and the proposed membrane can be a suitable alternative PEM or a separator for energy devices.     

Investigations on electrical properties of PVP:KIO4 polymer electrolyte films

Solid polymer electrolytes based on poly(vinyl pyrrolidone) (PVP) complexed with potassium periodide (KIO₄) salt at different weight percent ratios were prepared using solution-cast technique. X-ray diffraction (XRD) results revealed that the amorphous nature of PVP polymer matrix increased with the increase of KIO₄ salt concentration. The complexation of the salt with the polymer was confirmed by Fourier transform infrared (FTIR) spectroscopy studies. The ionic conductivity was found to increase with the increase of temperature as well as dopant concentration. The maximum ionic conductivity (1.421 × 10⁻⁴ S cm⁻¹) was obtained for 15 wt% KIO₄ doped polymer electrolyte at room temperature. The variation of ac conductivity with frequency obeyed Jonscher power law. The dynamical aspects of electrical transport process in the electrolyte were analyzed using complex electrical modulus. The peaks found in the electric modulus plots have been characterized in terms of the stretched exponential parameter. Optical absorption studies were performed in the wavelength range 200–600 nm and the absorption band energies (direct band gap and indirect band gap) values were evaluated. Using these polymer electrolyte films electrochemical cells were fabricated and their discharge characteristics were studied.     

Electrical and Structural Properties of Poly (Methyl Methacrylate) Doped Potassium Iodide (KI) Solid Polymer Electrolyte

A high-conducting salt-doped polymer electrolyte layer has been created here for use in photocell technologies. The solution casting method is used to produce ion conducting film where poly (methyl methacrylate) (PMMA) is used as the host polymer and potassium iodide (KI) as the dopant. The conductivity and amorphic increases of the polymer electrolytes with the addition of salt concentrations helps in the enhancement of the charge transfer properties. Using electrochemical impedance spectroscopy (EIS), ionic conductivity is evaluated where maximum conductivity is 3.99 × 10⁻⁶ S cm^-1 at 20 wt% KI concentration. Polarized optical microscopy (POM) shows the reduction in crystallinity by salt doping, while Fourier transforms infrared spectroscopy (FTIR) shows the complexation as well as composite nature of the film. Ionic transference number (t_ion) measurement shows the predominantly ionic nature of this polymer electrolyte.     

Preparation and characterization of pva based solid polymer electrolytes for electrochemical cell applications

Solid polymer electrolyte films containing poly(vinyl alcohol) (PVA) and magnesium nitrate (Mg(NO3)2) were prepared by solution casting technique and characterized by using XRD, FTIR, DSC and AC impedance spectroscopic analysis. The amorphous nature of the polymer electrolyte films has been confirmed by XRD. The complex formation between PVA and Mg salt has been confirmed by FTIR. The glass transition temperature decreases with increasing the Mg salt concentration. The AC impedance studies are performed to evaluate the ionic conductivity of the polymer electrolyte films in the range of 303 383 K, and the temperature dependence seems to obey the Arrhenius behavior. Transport number measurements show that the charge transport is mainly due to ions. Electrochemical cell of configuration Mg/(PVA + Mg(NO3)2) (70:30)/(I2 + C + electrolyte) has been fabricated. The discharge characteristics of the cell were studied for a constant load of 100 kΩ.     

Spectroscopic and Discharge Studies on Graphene Oxide Doped PVA/PVP Blend Nanocomposite Polymer Films

Graphene oxide (GO) nanoparticles were synthesized by modified Hummers method. The synthesized GO nanoparticles were incorporated in polyvinyl alcohol/polyvinyl pyrrolidone (PVA/PVP) blend polymers for the preparation of nanocomposite polymer films by solution cast technique. Different characterizations such as XRD, UV–Vis and FTIR were carried-out on to the prepared nanocomposite polymer films. The thermal analysis of the films was studied by DSC. The morphology of PVA/PVP:GO polymer films confirms GO was exfoliated within the PVA/PVP matrix and also reveals the heterogeneous phase of nanocomposite polymer electrolyte systems. From the conductivity studies the highest conductivity of PVA/PVP: GO (0.45: 0.3) was found to be 8.05 × 10^–4 S/cm at room temperature. Solid state battery has been fabricated with the configuration of Mg⁺/(PVA/PVP:GO)/(I₂ + C + electrolyte) and its cell parameters were calculated for a constant load of 100 kΩ.     

The effect of polyvinyl alcohol (PVA) on the optical,electrical and solid state properties of copper zinc tin sulfide (CZTS) deposited by sensitive spray pyrolysis (SSP)

Recently, the use of CZTS as the basis for other generation of low cost thin films solar cells has stimulated further researches. Its excellent p-type absorber nature, relatively high absorption coefficient and ideal energy band-gap of 1.5eV motivated these efforts. Additionally, CZTS consist of earth-abundant, cheap and non-toxic elements with very low manufacturing cost. Initially, copper indium gallium selenide (CIGS) solar cell device emerged but suffered limitations in further development because of rare indium and gallium in the device structure therefore, CZTS is recently preferred as an alternative to CIGS commercial solar cell absorber layer. In this work, solution mixture of CZTS and PVA was deposited on a substrate at temperature of 150 °C. Sensitive spray pyrolysis was used to grow the thin films where calculated amount of the precursor mixture was allowed to fall and be deposited on a heated substrate to form CZTS/PVA thin films. Subsequently, the thin film samples were annealed at a temperature of 200^oCfor 1 h to achieving pure crystalline thin film formation. SEM, XRD analysis, Optical, Solid State properties and Raman analysis were studied. The XRD analysis showed that the thin films fell into the pure kesterite structure of CZTS. Results show that produced thin films exhibited higher absorption coefficient and optical conductivity than pure CZTS, 10⁶ m^?1 and 10¹⁴(S^?1) against 10⁴cm^?1 and 10¹²(S^?1) respectively. The band-gap is between 1.53eV and 1.73eV. Using a PVA concentration of 0.05 M yielded highest absorbance and optical conductivity with lowest real dielectric constant and transmittance. These improved optical, electrical and solid state properties suitably qualify these thin films as absorber layer material for solar cell applications.     

Modification and characterization of semi-crystalline poly(vinyl alcohol) with interpenetrating poly(acrylic acid) by UV radiation method for alkaline solid polymer electrolytes membrane

Semi-crystalline poly(vinyl alcohol) was modified by UV radiation with acrylic acid monomer to get interpenetrating poly(acrylic acid) modified poly(vinyl alcohol), PVAAA, membrane. The stability of various PVAAA membranes in water, 2 M CH₃OH, 2 M H₂SO₄, and 40 wt% KOH aqueous media were evaluated. It was found that the stability of PVAAA membrane is stable in 40 wt% KOH solution. The PVAAA membranes were characterized by differential scanning calorimetry, X-ray diffraction, and thermogravimetry analysis. These results show that (1) the crystallinity in PVAAA decreased with increasing the content of poly(acrylic acid) in the PVAAA membranes. (2) The melting point of the PVAAA membrane is reduced with increasing the content of poly(acrylic acid) in the membrane. (3) Three stages of thermal degradation were found for pure PVA. Compared to pure PVA, the temperature of thermal degradation increased for the PVAAA membrane. The various PVAAA membranes were immersed in KOH solution to form polymer electrolyte membranes, PVAAA-KOH, and their performances for alkaline solid polymer electrolyte were conducted. At room temperature, the ionic conductivity increased from 0.044 to 0.312 S/cm. The result was due to the formation of interpenetrating polymer chain of poly(acrylic acid) in the PVAAA membrane and resulting in the increase of charge carriers in the PVA polymer matrix. Compared to the data reported for different membranes by other studies, our PVAAA membrane are highly ionic conducting alkaline solid polymer electrolytes membranes.     

Solid polymer electrolyte based on tragacanth gum-ammonium thiocyanate

Research towards solid polymer electrolytes based on biopolymers has grown extensively over the past years due to its abundance in nature, non-toxicity, low cost, and biodegradability. When compared to standard biopolymers, electrochemical study on natural gums is very limited. Therefore, in the present work, polymer electrolytes based on gum tragacanth have been prepared and characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), electrochemical impedance spectroscopy (EIS), thermogravimetry, and transference number studies. The polymer-salt complex formation is confirmed using FTIR studies while XRD spectra reveal the amorphous nature of the polymer membranes. The highest conductivity of 9.161?×?10^?3 S/cm was obtained for the film with 1 g of gum tragacanth and 0.5 g of ammonium thiocyanate. The Thermogravimetry study showed that the electrolyte is thermally stable. The transference number study confirmed that the main charge carriers are ions. The primary battery has been constructed using the prepared electrolyte, and the OCV was found to be 1.31 V.

     

Electrical and optical characterization of PMMA doped with Y0.0025Si0.025Ba0.9725 (Ti(0.9)Sn0.1)O3 ceramic

<正>Poly(methylmetacrylate)(PMMA)/Y_(0.0025)Si_(0.025)Ba_(0.9725)(Ti_((0.9))Sn_(0.1))O_3(YBTS) composites were prepared at different weight ratios of YBTS(0 wt%,5 wt%,10 wt%and 20 wt%YBTS) in order to investigate effect of YBTS additions on the electrical and optical properties of PMMA host.The electrical properties(impedance,dielectric constant dielectric loss and AC conductivity) were studied in the frequency range 10 kHz-1 MHz and in temperature range 20-90℃.Upon increasing the contents of YBTS ceramic,we observed a reduction in the impedance and an increase in the dielectric constant,dielectric loss and AC conductivity of PMMA host.We also found that the relaxation process at high YBTS contents was due to relaxation in the ionic conductivity.The absorption coefficient(α) has been determined in the wavelength range 230-800 nm at room temperature for all YBTS-PMMA composites.Moreover,the addition of YBTS ceramic highly enhances the UV absorption of PMMA host especially below 300 nm.Addition of 20 wt%YBTS ceramic to PMMA host decreases the optical energy gap from 5 eV to 3.41 eV.Correlations between electrical,optical and SEM results are reported.     

The origin of DC electrical conduction and dielectric relaxation in pristine and doped poly(3‐hexylthiophene) films

We present here the evidence for the origin of dc electrical conduction and dielectric relaxation in pristine and doped poly(3‐hexylthiophene) (P3HT) films. P3HT has been synthesized and purified to obtain pristine P3HT polymer films. P3HT films are chemically doped to make conducting P3HT films with different conductivity level. Temperature (77–350 K) dependent dc conductivity (σ_dc) and dielectric constant (ε′(ω)) measurements on pristine and doped P3HT films have been conducted to evaluate dc and ac electrical conduction parameters. The relaxation frequency (f_R) and static dielectric constant (ε₀) have been estimated from dielectric constant measurements. A correlation between dc electrical conduction and dielectric relaxation data indicates that both dc and ac electrical conductions originate from the same hopping process in this system. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1047–1053, 2010     

Structure and ion transport in an ethylene carbonate-modified biodegradable gel polymer electrolyte

The influence of ethylene carbonate (EC) addition on 85poly(ε-caprolactone):15Lithium thiocyanate (85PCL:15LiSCN) polymer electrolyte is investigated using X-ray diffraction, impedance spectroscopy, Wagner's polarization and electrochemical measurements. The results reveal that the amorphicity of the 85PCL:15LiSCN system increases with increase of EC content up to an optimal level of 40 wt.%. This is reflected in the electrical properties of the gel polymer electrolytes, i.e., the 40 wt.% EC-incorporated gel polymer electrolyte exhibits both high amorphicity and high electrical conductivity as compared to the other samples. The EC concentration dependences of dielectric constant and electrical conductivity show a similar trend, indicating that these properties are closely related to each other. The total ionic transference numbers of EC-incorporated gel polymer electrolytes are in the range 0.989–0.993, demonstrating that they are almost completely ionic conductors. The electrochemical stability window of the 40 wt.% EC-incorporated gel polymer electrolyte is ∼4.1 V along with the electrical conductivity of 2.2 × 10⁻⁴ S cm⁻¹, which is significantly improved as compared to the 85PCL:15LiSCN system (3.0 V and 1.04 × 10⁻⁶ S cm⁻¹). Consequently, the addition of EC in the 85PCL:15LiSCN polymer electrolyte leads to a promising improvement in its various properties.     

PVA-膨润土-KOH-H2O复合碱性聚合物电解质的制备与表征

以聚乙烯醇(PVA)与膨润土(bentonite)和氢氧化钾为原料, 采用溶液浇铸法制备了PVA-膨润土-KOH-H2O复合碱性聚合物电解质膜. 运用X衍射(XRD)、扫描电镜(SEM)和循环伏安(CV)等技术对复合膜进行了表征, 分析了膨润土对聚合物膜电导率的影响. 结果表明, 膨润土对电解质的导电性能具有双重作用: 一方面膨润土本身会阻塞PVA内部结构中的部分离子通道, 导致复合电解质的电导率降低; 另一方面, 膨润土有助于体系中KOH含量的增加, 同时PVA-膨润土相界面高导电性缺陷层的形成有助于体系电导率的提高. 当体系水的质量分数较低时, 复合电解质体系电导率存在极大值; 当w(H2O)为65%时, 则观察到电导率的线性增加趋势; 电解质最高室温电导率达0.110 S·cm-1. XRD图谱显示适当配比的复合膜中PVA呈无定形态; SEM结果证实了适当配比的复合膜中存在大量微米级孔径的微孔通道. 循环伏安曲线表明PVA-膨润土-KOH-H2O碱性聚合物电解质膜有约2.0 V的较宽电化学稳定窗口.     

Ion- Beam Modification of Peo Based Polymer Electrolytes

In this paper, we report the ion beam interaction with a well explored ion conducting polymer electrolyte, viz., polyethylene oxide complexed with sodium iodide (PEO:NaI). Li³⁺ ions at 50 MeV were bombarded on the film at different flux. The conductivity modulation of the films has been reported due to interaction at different fluence. The increase in the total conductivity is explained in terms of the change in the number of charge carriers and the dielectric constant of the polymer electrolyte films.     

聚苯并咪唑-锂盐-聚乙二醇单甲醚共混全固态聚合物电解质的制备及性能

使用共混后浇铸成膜的方法,制备了聚苯并咪唑-锂盐-聚乙二醇单甲醚组成的锂离子电池共混全固态聚合物电解质。通过傅里叶红外光谱(FT-IR)、X射线衍射(XRD)、差示扫描量热(DSC)、拉伸与交流阻抗测试表征了共混全固态电解质的结构与性能。研究了不同锂盐以及各组分含量对共混全固态电解质的力学性能与电导率的影响。结果表明:聚苯并咪唑与聚乙二醇单甲醚之间存在氢键;共混全固态电解质中聚乙二醇单甲醚处于无定形态;锂盐的加入使聚乙二醇单甲醚的玻璃化转变温度下降;聚乙二醇单甲醚含量越高,共混膜强度越低,电导率越高,并且使用三氟甲磺酸锂作为锂盐时其电导率最高,室温下可以达到3.58×10~(-5) S/cm,高温下可以达到3.3×10~(-3) S/cm,高温下满足对锂离子电池的使用需求。     

Synthesis and characterization of bisulfonated poly(vinyl alcohol)/graphene oxide composite membranes with improved proton exchange capabilities

Composite membranes based on poly(vinyl alcohol) (PVA) and graphene oxide (GO) were prepared by solution-casting method to be used as proton exchange membranes (PEMs) in fuel cell (FC) applications. Bisulfonation was employed as a strategy to enhance the proton conductivity of these membranes. First, a direct sulfonation of the polymer matrix was accomplished by intra-sulfonation of the polymer matrix with propane sultone, followed by the inter-sulfonation of the polymer chains using sulfosuccinic acid (SSA) as a crosslinking agent. Furthermore, the addition of graphene oxide (GO) as inorganic filler was also evaluated to enhance the proton-conducting of the composite membranes. These membranes were fully characterized by scanning electron microscopy (SEM), Fourier transformed infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and tensile tests. Besides, the proton conductivity of these membranes in a fully hydrated state was also analyzed by electrochemical impedance spectroscopy (EIS). The effect of the intra- and inter-sulfonation of the polymer matrix on the structural, morphological, thermal and mechanical properties of the membranes were determined. Increasing the density of sulfonic acid groups in the membranes resulted in a trade-off between a better proton conductivity (improving from 0.26 to 1.00 mS/cm) and a decreased thermal and mechanical stability. In contrast, the incorporation of GO nanoparticles into the polymer matrix improved the thermal and mechanical stability of both bisulfonated composite membranes. The proton conductivity appreciably increased by the combination of bisulfonation and introduction of GO nanoparticles into the polymer matrix. The sPVA/30SSA/GO composite membrane exhibited a proton conductivity of 1.95 mS/cm at 25 °C. The combination of the GO nanoparticles with the chemical bisulfonation approach of PVA allows thus assembling promising proton exchange membrane candidates for fuel cell applications.     

Dynamic mechanical and dielectrical properties of poly(vinyl alcohol) and poly(vinyl alcohol)‐based nanocomposites

In this article we report on the investigation of the dynamics of poly(vinyl alcohol) (PVA) and PVA‐based composite films by means of dielectric spectroscopy and dynamic mechanical thermal analysis. Once the characterization of pure PVA was done, we studied the effect of a nanostructured magnetic filler (nanosized CoFe₂O₄ particles homogeneously dispersed within a sulfonated polystyrene matrix) on the dynamics of PVA. Our results suggest that the α‐relaxation process, corresponding to the glass transition of PVA, is affected by the filler. The glass‐transition temperature of PVA increases with filler content up to compositions of around 10 wt %, probably as a result of polymer–filler interactions that reduce the polymer chain mobility. For filler contents higher than 10 wt %, the glass‐transition temperature of PVA decreases as a result of the absorption of water that causes a plasticizing effect. The β‐ and γ‐relaxation processes of PVA are not affected by the filler as stated from both dynamic mechanical thermal analysis and dielectric spectroscopy. Nevertheless, both relaxation processes are greatly affected by the moisture content. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 1968–1975, 2001