Effect of incorporation of different plasticizers on structural and ion transport properties of PVA-LiClO4 based electrolytes

To date high ionic conducting polymer electrolytes are of great interest because of their potential applications in various electrochemical devices such as batteries, fuel cells, solar cells and super capacitors etc., as electrolytes. Ion conduction through polymer electrolytes can occur mostly in amorphous environment exists above their glass transition temperature (Tg). In order to improve ionic conductivity, many approaches such as addition of plasticizer, blending of polymers, nano composite have been employed. This paper reviews the influence of different plasticizers/additives on the ion transport mechanism of Poly(vinyl alcohol) (PVA)-LiClO4 polymer electrolytes since poly vinyl alcohol is a semi crystalline, synthetic biodegradable polymer and lithium perchlorate is one of the most moisture resistant lithium salts. This review also reveals the relation between dynamical disorder in polymer electrolyte with ionic conductivity

Vibrational, electrical, dielectric and optical properties of PVA-LiPF6 solid polymer electrolytes

Solid polymer electrolytes based on polyvinyl alcohol (PVA) doped with LiPF6 have been prepared using solution casting technique. Electrical properties of prepared electrolyte films were analyzed using AC impedance spectroscopy. The ionic conductivity was found to increase with increasing salt concentration. The maximum conductivity of 8.94 × 10−3 S·cm−1 was obtained at ambient temperature for the film containing 20 mol% of LiPF6. The conductivity enhancement was correlated to the enhancement of available charge carriers. The formation of a complex between the polymer and salt was confirmed by Fourier transform infrared spectroscopy (FT-IR). The optical nature of the polymer electrolyte films was analyzed through UV-Vis spectroscopy

Ionic Conductivity studies on Plasticized Proton conducting solid polymer electrolyte complexes PVA -NH 2 SO 3 H-PEG

Abstract : An attempt was made in the present work to develop a new plasticized proton conducting polymer electrolytes comprising of Poly (vinyl alcohol) (PVA) -Sulfamic Acid (SA) -Poly ethylene glycol (PEG 400 ). The role of the plasticizer was studied in terms of dc conductivity (σ dc ), activation energy (E a ) and mobility of the charge carrier (μ) using ac impedance spectroscopy. The dc conductivity was enhanced by two order of magnitude for 48 mol % of PEG plasticized polymer electrolyte than the unplasticized polymer electrolyte at 313K. The low activation energy (0.445eV) and high mobility of the charge carrier (4.42x10 -8 cm 2 v -1 s -1 ) were observed for the plasticized polymer electrolyte

Ionic conductivity studies on LiSmO(2) by impedance spectroscopy

Lithium samarium oxide has been prepared by solid-state reaction method and characterized by X-ray diffraction (XRD) and impedance spectroscopy. XRD pattern of the sample reveals the formation of the sample. The conductivity studies, dielectric studies, and modulus analysis of the samples have been carried out for different temperatures. The bulk conductivity of the sample has been found to be 1.21 x 10(-5) Scm(-1) at 420 A degrees C. The temperature variation of the direct current conductivity obeys the Arrhenius relation. The modulus analysis of the sample indicates the non-Debye nature of the sample which corresponds to long-time slow polarization and relaxation of hopping charges

Hydrothermal impact of multiwall carbon nanotube diameter in a conventional square cavity

This study aimed to computationally examine the effect of the average diameter of multiwall carbon nanotubes (MWCNTs) on the hydrothermal properties of a square cavity. A conventional square cavity filled with MWCNT–water was used for the experiment. The left and right walls of the cavity are maintained as hot and cold respectively, whereas the top and bottom walls were assumed to be adiabatic. Mathematical models were developed using the Navier–Stokes equations by applying the thermophysical properties of the MWCNT–water nanofluid. A newly proposed correlation between the effective thermal conductivity and the diameter of carbon nanotube was utilized to analyze the impact of the average diameter on the natural convection of nanofluid inside the cavity. The governing equations were non-dimensionalized using suitable variables and then solved using the Galerkin finite element technique. The combined effects of the Rayleigh number (103<Ra<106) and the average diameter of the MWCNTs (10 nm to 30 nm) on the streamlines, isolines, velocity, local Nusselt number, and mean Nusselt number were examined in detail. It is found that the flow and heat transfer rate inside the cavity can be effectively controlled by increasing the average diameter of MWCNTs at higher Rayleigh numbers compared to lower Rayleigh number. A larger MWCNT diameter dominated the impact of the buoyancy force inside the square cavity

Preparation and characterization of PVA/PAM/NH4SCN polymer film by ultrasound-assisted solution casting method for application in electric double layer capacitor

The structural analysis of PVA/PAM blend polymer electrolytes made in the different ratio of 70: 30, 50: 50 and 30: 70 by ultrasound-assisted solution casting technique shows a good miscibility between the polymers. The different weight percentage of ammonium thiocyanate (NH4SCN) salt as an ionic dopant was added to the PVA/PAM (50: 50) blend film and tested for the structural changes, electrical and electrochemical properties. The 50 wt% PVA-50 wt% PAM-20 wt% NH4SCN (UN20) blend film prepared in the presence of ultrasound exhibits a high conductivity value of 1.66 x 10(-4) S cm(-1), whereas the above blend membrane prepared in the absence of ultrasound (WN20) exhibits a conductivity value of 3.98 x 10(-5) S cm(-1). The electric double-layer capacitor (EDLC) fabricated using the activated carbon as the electrode and the film UN20 as the polymer electrolyte exhibited a specific capacitance value of 1230 mF g(-1) as observed by the cyclic voltammetry studies, whereas the EDLC made with the film WN20 exhibited a poor specific capacitance value of 293 mF g(-1). The charge-discharge studies of the device made using the film UN20 was found to exhibit a first cycle discharge capacitance of 2562 mF g(-1) for a current load of 1 mA in the voltage range of 0-1 V. The reasons for the changes in the properties of the films prepared in presence and in absence of the ultrasound and its effect in performance of EDLC were discussed

Effects of vertically embedded parallel hot elliptic obstacles inside a fully sinusoidal enclosure filled with SWCNT–water nanofluid

Advancements in nanotechnology, particularly the use of nanofluids for heat transfer, have been receiving significant attention for improving the efficacy of heat transfer in systems that employ thermal, electronic, medical, and transportation applications. The thermal performance of a two-dimensional, incompressible flow of single-wall carbon nanotube (SWCNT)–water nanofluid inside a completely sinusoidal enclosure under cold boundary conditions was examined numerically. The impacts of two vertically embedded parallel elliptical hot obstacles have been discussed with respect to thermal radiation. The consequences of flow and thermal control parameters such as the Rayleigh number (104 ≤ RaE ≤ 106), volume fraction of SWCNTs (1.5% ≤ ς ≤ 5.5%), and radiation parameters (0 ≤ Nr ≤ 2) with elliptical obstacles of different sizes were studied through streamlines, isolines, and local and mean Nusselt number plots. To analyze the radiation impact, Rosseland thermal radiation was incorporated into the energy equation. A modified correlation for the thermal conductivity of the SWCNT and base fluid was considered. The Galerkin finite element method was applied to numerically solve the dimensionless equations with appropriate boundary conditions. The mean Nusselt number increased with the increasing size of the vertical semi-major axes of the elliptical obstacles

Structural, dielectric, and conductivity studies of yttrium-doped LiNiPO(4) cathode materials

Olivine-structured pure LiNiPO(4) and yttrium-doped LiNiPO(4) have been synthesized by a Pechini-type polymerizable precursor method. Compound formation temperature is confirmed from thermogravimetry to differential thermal analysis. Powder X-ray diffraction pattern confirmed the formation of phase pure LiNiPO(4) compound with an orthorhombic structure with fine crystallite size. Presence of preferred local cation environment is understood from Fourier transform infrared spectroscopy (FTIR) studies. XRD and FTIR studies show that doped yttrium ion entered in the lattice of LiNiPO(4.) It has been found that the ionic conductivity of LiNiPO(4) is enhanced by around two orders of magnitude by doping yttrium. Dielectric spectra show the decrease in dielectric constant with increase in frequency. Dielectric loss spectra reveal that dc conduction contribution predominates in the sample