Metal framework as a novel approach for the fabrication of electric double layer capacitor device with high energy density using plasticized Poly(vinyl alcohol): Ammonium Thiocyanate based Polymer Electrolyte

High performance electric double-layer capacitors (EDLCs) based on poly (vinyl alcohol) (PVA): ammonium thiocyanate (NH4SCN):Cu(II)-complex plasticized with glycerol (GLY) have been fabricated. The maximum DC ionic conductivity (σDC) of 2.25 × 10-3 S cm-1 is achieved at ambient temperature. The X-ray diffraction (XRD) patterns confirmed that the addition of both Cu(II)–complex and GLY enhanced the amorphous region within the samples. Through the Fourier transform infrared (FTIR) the interactions between the host polymer and other components of the prepared electrolyte are observed. The FESEM images reveal that the surface morphology of the samples showed a uniform smooth surface at high GLY concentration. This is in good agreement with the XRD and FTIR results. Transference numbers of ion (tion) and electron (tel) for the highest conducting composite polymer electrolyte (CPE) are recognized to be 0.971 and 0.029, respectively. The linear sweep voltammetry (LSV) revealed that the electrochemical stability window for the CPE is 2.15 V. These high values of tion and potential stability established the suitability of the synthesized systems for EDLC application. Cyclic voltammetry (CV) offered nearly rectangular shape with the lack of Faradaic peak. The specific capacitance and energy density of the EDLC are nearly constant within 1000 cycles at a current density of 0.5 mA/cm2 with average of 155.322 F/g and 17.473 Wh/Kg, respectively. The energy density of the EDLC in the current work is in the range of battery specific energy. The EDLC performance was found to be stable over 1000 cycles. The low value of equivalent series resistance reveals that the EDLC has good electrolyte-electrode contact. The EDLC exhibited the initial high power density of 4.960 × 103 W/K

Effect of ohmic-drop on electrochemical performance of EDLC fabricated from PVA:dextran:NH4I based polymer blend electrolytes

Proton conducting solid polymer blend electrolytes based on poly(vinyl alcohol)(PVA):dextran that were doped with different quantities of ammonium iodide (NH4I) were prepared. The X-ray diffraction (XRD) and Fourier-transform infrared (FTIR) study were carried out to examine the compatibility of NH4I withPVA:dextran polymers. FTIR spectroscopy assessment was used to establish the presence of a complex formation between the PVA:dextran and added salt through the modification and reduction in the intensity of FTIR bands relevant to the functional groups. The field emission scanning electron microscopy (FESEM) examination was used to assess the channels for proton transport. Electrical impedance spectroscopy (EIS) was used to analyse the samples conductivity behaviour. The sample with 20 wt.% of added salt has shown a high DC conductivity which can be employed in electrochemical devices such as EDLC. It is also demonstrated by the transference number (TNM) and linear sweep voltammetry (LSV) that it is appropriate to use the largest conducting sample for electrochemical device. There was electrochemical stability of the electrolyte sample with voltage sweeping linearly to 1.3 V. It is shown by the outcome of cyclic voltammetry (CV) plot that charge storage at the site of electrode-electrolyte is non-Faradiac. A high drop voltage (Vd=IR) is implied by the usual galvanostatic charge-discharge. The equivalent series resistance (Res) increases as a result of the increase in Vd all the way through the charge-discharge cycle. Specific capacitance (Csp) is nearly constant from the foremost cycle to the 100th cycle, with average of 4.2 F/g

Electrochemical characterizations and the effect of glycerol in biopolymer electrolytes based on methylcellulose-potato starch blend

Polymer electrolytes have been prepared by blending methylcellulose (MC)-potato starch, doped with lithium perchlorate (LiClO4) and plasticized with glycerol. The blend of 60 wt% MC-40 wt% starch was found to be the most suitable ratio to serve as polymer host. Fourier transform infrared (FTIR) spectroscopy analysis proved the interaction among the components. X-ray diffraction (XRD) analysis indicated that the conductivity enhancement is due to the increase in amorphous content. The highest ionic conductivity obtained at room temperature was (4.25 ± 0.82) × 10−4 S cm−1 for MC-starch-LiClO4-20 wt% glycerol. The highest conducting samples in both systems were found to obey Arrhenius rule. Dielectric study further strengthens the conductivity result

Structural, morphological and electrochemical impedance study of CS: LiTf based solid polymer electrolyte: Reformulated arrhenius equation for ion transport study

This paper discusses ion conduction mechanism in terms of reformulated Arrhenius equation. Understanding the fundamental concepts of Li ion transport is crucial for Li battery technology. Structural and morphological investigations are significant to understand the structure-properties relationships. The broadening of X-ray peaks of chitosan upon the addition of LiTf salt reveals that the crystalline domains are reduced. The SEM micrographs reveal that the samples have a smooth surface. Electrochemical impedance spectroscopy (EIS) was used to obtain the electrical and dielectric parameters. The dielectric constant and DC ionic conductivity follows the same trend with salt concentration. The behavior of Arrhenius and modified Arrhenius equations versus temperature are clarified. The influence of dielectric constant on DC conductivity experimentally achieved. The reformulated Arrhenius equation exhibited more linearity between the DC conductivity and 1000/(ε'×T). The shortcoming of Arrhenius equation can be understood from the less linear behavior of DC conductivity versus 1000/T. The pre-exponential factor is almost constant at different temperature and independent on dielectric constant. The calculated activation energy from the reformulated Arrhenius equation is greater than that obtained from Arrhenius equation

The effect of LiCF3SO3 on the complexation with potato starch-chitosan blend polymer electrolytes

This work examines the effect of lithium trifluoromethanesulfonate (LiCF3SO3) and glycerol on the conductivity and dielectric properties of potato starch-chitosan blend-based electrolytes. The electrolytes are prepared via solution cast technique. From X-ray diffraction (XRD) analysis, the blend of 50 wt.% starch and 50 wt.% chitosan is found to be the most amorphous blend. Fourier transform infrared (FTIR) spectroscopy studies show the interaction between the electrolyte materials. The room temperature conductivity of pure starch-chitosan film is found to be (2.85 ± 1.31) × 10−10 S cm−1. The incorporation of 45 wt.% LiCF3SO3 increases the conductivity to (7.65 ± 2.27) × 10−5 S cm−1. Further conductivity enhancement up to (1.32 ± 0.35) × 10−3 S cm−1 has been observed on addition of 30 wt.% glycerol. This trend in conductivity is verified by XRD and dielectric analysis. The temperature dependence of conductivity of all electrolytes are Arrhenian

Chitosan-PEO proton conducting polymer electrolyte membrane doped with NH 4NO 3

The polymer electrolyte membrane in this work was prepared using the solution casting technique. The polymer host is a blend of chitosan and polyethylene oxide. The solution of the blend was added with ammonium nitrate (NH 4NO 3) to supply the charge carriers for ionic conduction. From X-ray diffraction and scanning electron microscopy image, it can be inferred that the film of the 3 : 2 chitosan-polyethylene oxide blend is the most amorphous and suitable to serve as polymer host. The sample containing 40 wt-%NH 4NO 3 exhibited the highest room temperature conductivity of 1.02×10 -4 S cm -1. The salted samples were also characterised using X-ray diffraction and scanning electron microscopy in order to establish conductivity variation with different salt contents. © W. S. Maney & Son Ltd. 2011

Plasticized chitosan-PVA blend polymer electrolyte based proton battery

This paper focused on the transport studies of PVA-chitosan blended electrolyte system and application in proton batteries. The electrolytes were prepared by the solution cast technique. In this work, 36 wt.% PVA and 24 wt.% chitosan blend doped with 40 wt.% NH(4)NO(3) exhibited the highest room temperature conductivity. The conductivity value obtained was 2.07 x 10(-5) S cm(-1). EC was then added in various quantities to the 60 wt.% [60 wt.% PVA-40 wt.% chitosan]-40 wt.% NH(4)NO(3) composition in order to enhance the conductivity of the sample. The highest conductivity obtained was 1.60 x 10(-3) S cm(-1) for the sample containing 70 wt.% EC. The Rice and Roth model was applied to analyze the conductivity enhancement. The highest conducting sample in the plasticized system was used to fabricate several batteries with configuration Zn//MnO(2). The open circuit potential (OCP) of the fabricated batteries was between 1.6 and 1.7 V. (C) 2009 Elsevier Ltd. All rights reserved

Electrical impedance and conduction mechanism analysis of biopolymer electrolytes based on methyl cellulose doped with ammonium iodide

In the present study, the potential of methyl cellulose (MC) as biopolymer electrolyte (BPE) will be studied extensively by means of conductivity and the conduction mechanism. BPE films based on MC doped with ammonium iodide (NH4I) salt were prepared by solution-casting method. X-ray diffraction (XRD) explains that the conductivity enhancement of the electrolytes is affected by the degree of crystallinity. Field emission scanning electron microscopy (FESEM) analysis shows the difference in the electrolyte’s surface with respect to NH4I. On addition of 40 wt.% of NH4I, the highest room temperature conductivity of (5.08 ± 0.04) × 10−4 S cm−1 was achieved. The temperature dependence relationship for the salted electrolyte was found to obey the Arrhenius rule where R2 ∼1 from which the activation energy (Ea) was evaluated. The dielectric study analyzed using complex permittivity ε* for the sample with the highest conductivity at elevated temperature shows a non- Debye behavior. These salted electrolytes follow the correlated barrier hopping (CBH) model

FTIR Studies of plasticized poly(vinyl alcohol)-chitosan blend doped With NH4NO3 polymer electrolyte membrane

Fourier transform infrared (FTIR) spectroscopy studies of poly(vinyl alcohol) (PVA), and chitosan polymer blend doped with ammonium nitrate (NH4NO3) salt and plasticized with ethylene carbonate (EC) have been performed with emphasis on the shift of the carboxamide, amine and hydroxyl bands. 1% acetic acid solution was used as the solvent. It is observed from the chitosan film spectrum that evidence of polymer-solvent interaction can be observed from the shifting of the carboxamide band at 1660 cm(-1) and the amine band at 1591 cm(-1) to 1650 and 1557 cm(-1) respectively and the shift of the hydroxyl band from 3377 to 3354 cm(-1). The hydroxyl band in the spectrum of PVA powder is observed at 3354 cm(-1) and is observed at 3343 cm(-1) in the spectrum of the PVA film. On addition of NH4NO3 up to 30 wt.%, the carboxamide, amine and hydroxyl bands shifted from 1650, 1557 and 3354 cm(-1) to 1642, 1541 and 3348 cm(-1) indicating that the chitosan has complexed with the salt. In the PVA-NH4NO3 spectrum, the hydroxyl band has shifted from 3343 to 3272 cm(-1) on addition of salt from 10 to 30 wt.%. EC acts as a plasticizing agent since there is no shift in the bands as observed in the spectrum of PVA-chitosan-EC films. The mechanism of ion migration is proposed for the plasticized and unplasticized PVA-chitosan-NH4NO3 systems. In the spectrum of PVA-chitosan-NH4NO3-EC complex, the doublet C=O stretching in EC is observed in the vicinity 1800 and 1700. This indicates that there is some interaction between the salt and EC. (C) 2010 Elsevier B.V. All rights reserved

A conceptual review on polymer electrolytes and ion transport models

This review article provides a deep insight into the ion conduction mechanism in polymer electrolytes (PEs). The concepts of different categories of polymer electrolytes are discussed. The significance of the existence of functional (polar) groups on the backbone of host polymers, which are used in polymer electrolytes, is well explained. The working principle of electrical impedance spectroscopy (EIS) is overviewed. The relationship between impedance plots and equivalent circuits, which are crucial for electrical characterization, is extensively interpreted. Based on the patterns of dc conductivity (σdc) versus 1000/T, the ion transport models of Arrhenius and Vogel–Tammann–Fulcher (VTF) are discussed. Effects of coupling and decoupling between ionic motion and polymer segmental relaxation are analyzed. The important role of dielectric constant on cationic transport in PEs is also explained. The relationships existing between electrical and dielectric parameters are elucidated, which help interpret and understand the ion conduction mechanism. From the reported empirical curves of dc conductivity vs. dielectric constant, the reformulated Arrhenius [σdc(T)=σ0exp(−EakBTε′)] equation is proposed. Finally, other important phenomena, occurring in polymer electrolytes, are shown to be understandable from the dielectric constant studies. Keywords: Polar polymers, Polymer electrolytes, Electrical impedance spectroscopy, Impedance plots, Arrhenius model, Vogel–Tammann–Fulcher (VTF) model, Reformulated Arrhenius mode