Ab Malik Marwan Ali

Electrical conductivity studies on PVA/PVP-KOH alkaline solid polymer blend electrolyte

A series of conducting thin-film solid electrolytes based on poly (vinyl alcohol)/ poly (vinyl pyrrolidone) (PVA/PVP) polymer blend was prepared by the solution casting technique. PVA and PVP were mixed in various weight percent ratios and dissolved in 20 ml of distilled water. The samples were analyzed by using impedance spectroscopy in the frequency range between 100 Hz and 1 MHz. The PVA/PVP system with a composition of 80% PVA and 20 wt.% PVP exhibits the highest conductivity of (2.2±1.4) × 10−7 Scm−1. The highest conducting PVA/PVP blend was then further studied by adding different amounts of potassium hydroxide (KOH) ionic dopant. Water has been used as solvent to prepare PVA/PVP-KOH based alkaline solid polymer blend electrolyte films. The conductivity was enhanced to (1.5 ± 1.1) × 10−4 Scm−1 when 40 wt.% KOH was added.

Studies on cellulose acetate-based gel polymer electrolytes for proton batteries

Abstract Biomaterial-based cellulose is biodegradable, biocompatible and possesses good mechanical properties. Previous studies have proven that it can be used as the separator for various kinds of batteries, such as lead–acid batteries, silver–zinc rechargeable batteries, as an additive for preparation of pasted zinc electrodes for zinc–air batteries and as binders/surface modifiers for graphite anodes for lithium batteries. However, it never intensively been used as a polymer electrolyte in advanced batteries. Substantial progress has been made in the development of proton conductors with high ionic conductivity. Hence, proton batteries can be considered as cost effective alternatives for battery applications. The present study involves the fabrication and characterisation of gelled cellulose polymer proton battery with the configuration Zn/composite cellulose electrolytes/MnO2. The open circuit voltage (OCV) of the cell is ∼1·6 V. The constancy of OCV was tested for over 24 h. The discharge capacity was 24·65 mA h for 0·5 mA and 22·41 mA h for 1 mA.

First Principles LDA+U Calculations for ZnO Materials

The electronic, structural, elastic, and optical properties of zinc oxide (ZnO) with wurtzite-type structure were investigated using first-principles calculation based on density functional theory (DFT) with local density approximation (LDA) plus Hubbard U (DFT–LDA+U)method. Hubbard U improved the calculated results, allowing it to exhibit good agreement with experimental data. The DFT–LDA+U method successfully predicted the electronic properties of ZnO with better described the localization of transition metal Zn 3d electron. The calculated optical dielectric function of ZnO and its relation with electronic properties were further discussed.

ELECTRICAL PROPERTIES OF PEO-LiCF3SO3-SiO2 NANOCOMPOSITE POLYMER ELECTROLYTES

Abstract Nanoparticle oxide fillers such as SiO2 have been previously shown to affect the properties of polymer electrolytes, especially those based on polyether–lithium salt systems. In this work nanocomposite solid polymer electrolyte films composed of polyethyleneoxide (PEO), lithium triflate (LiCF3SO3) and SiO2 nanofiller (15 nm in size) have been prepared by using solution cast method. At room temperature, the sample 80PEO–20LiCF3SO3 (wt-%) was found to have the highest conductivity of about 2·04 × 10–7 S cm–1. The 88PEO–LiCF3SO3–12SiO2 (wt-%) has high ionic conductivity of about 1·28 × 10–3 S cm–1 at room temperature. The effects of concentration of filler on the dielectric properties of the electrolytes were also studied. Temperature effects on the dielectric properties revealed that the electrolytes to be of the non-Debye type.

Electrical Properties of Plasticized Chitosan-Lithium Imide with Oleic Acid- Based Polymer Electrolytes for Lithium Rechargeable Batteries

Solid polymer electrolytes (SPEs) were prepared and their electrochemical characteristics were characterized. The composition of SPEs containing chitosan, lithium trifluoromethane sulfonimide (LiN(CF3SO2)2) and oleic acid (OA) was optimized employing ac impedance measurements at various temperatures. The electrical conductivity of the SPEs with OA shows the highest value and the presence of OA does not change the structure of the polymer.

Natural rubber-grafted with 30% poly(methylmethacrylate) characterization for application in lithium polymer battery

In this study, a composite plasticized polymer electrolytes (CPEs) compassed of 30% methyl grafted natural rubber (MG30) doped with lithium triflate (LiTf) and silicon dioxide (SiO2) was prepared by solution cast technique. The polymer-salt complexation has been confirmed by ATR-FTIR spectral studies. The CPEs were then investigated as an ionic conducting polymer. The conductivity of the CPEs was measured by AC impedance spectroscopy and shows that the sample containing 60 wt.% MG30:33 wt.% LiTf:7 wt.% SiO2 exhibit the highest conductivity of up to 10−4 S.cm−1 at room temperature. In order to understand the thermal effect on the ionic migration in the CPEs, temperature dependent-conductivity was performed as a function of temperature between 300 K and 363 K and demonstrates that the conductivity of CPEs depart from the Arrhenius rule. The modulus formalism studies establish the CPEs films behave as an ionic conductor and confirmed by ionic transference number.

PLASTICIZED PVA/PVP–KOH ALKALINE SOLID POLYMER BLEND ELECTROLYTE FOR ELECTROCHEMICAL CELLS

Solid polymer electrolytes comprising a blend of poly (vinyl alcohol) (PVA) and poly (vinyl pyrrolidone) (PVP) with different concentration of potassium hydroxide (KOH) as ionic dopant were prepared using a solution–casting technique. The conductivity was enhanced to (1.5 ± 1.1) × 10-4S cm-1 when 40 wt.% KOH was added. The highest conductivity exhibited when 20 wt.% ethylene carbonate (EC) and 30 wt.% propylene carbonate (PC) was added into the PVA/PVP–KOH sample electrolytes. Conductivity–temperature dependence of the plasticized samples was established to obey an Arrhenian relationship with the activation energy of the order of 0.08–0.4 eV, depending on the plasticizer concentration. Electrochemical cells of Zn|PVA/PVP–KOH + EC|MnO2 and Zn|PVA/PVP–KOH + PC|MnO2 have been fabricated. The discharge characteristics of the cells are considered under a constant current of 1 mA. The open circuit voltage (OCV) and discharge capacity of the cells are measured.

First-principles study on structural, electronic and optical properties of TiO2 for dye-sensitized solar cells photoanode

First-principles study based on density functional theory (DFT) framework for structural, electronic and optical properties of titanium dioxide (TiO2) in anatase and rutile phases are investigated. Anatase phase exhibits wide band gap compare to rutile phase. The partial and total density of states for TiO2 (anatase and rutile) describes the occupying of titanium (Ti) and oxygen (O) atoms at each energy level. TiO2 has a high dielectric constant to avoid the recombination process while its high refractive index provides the efficient of light diffusion. The optical absorption of TiO2 occurs in ultraviolet (UV) light of the wavelength photon. The results from the first-principles calculations will be helpful to give an understanding about the properties of TiO2 as promising photoanode in dye-sensitized solar cell (DSSC).

Excitation and Emission Properties of Poly(N-Carbazole)/Poly(vinylpyrrolidone) Blends Characterized by Fluorescence Spectroscopy

We present the results concerning the excitation and emissions spectra of Poly (N-carbazole) (PVK) blend with different compositions of polyvinylpyrrolidone (PVP). Doctor blade technique was used to coat the blended polymer on a quartz substrate. The influences of polymer composition to the excitation and emission spectra were observed under UV excitation source of a xenon lamp. The result shows a discrepancy in the maximum excitation, emission and Stokes shift for each samples. The variation of Full Width at Half Maximum (FWHM) for excitation and emission indicate that the variation in composition has affected on the fluorescence properties of the blended thin film polymer system. Fourier Transform Infrared (FTIR) spectroscopy reveals that the discrepancy in the emission and excitation properties of this polymer blending system is due to the discrepancy of infrared absorption peak in the carbazole functional group.

The preparation and characterization of sulfonated poly (ether ether ketone) and Cellulose Acetate (SPEEK-CA) membrane in proton exchange membrane fuel cells (PEMFCs) by UV-crosslink technique

A new series of cross linked proton conducting membranes consists of sulfonated poly (ether ether ketone) (SPEEK) and Cellulose Acetate (CA) has been developed over a wide range of compositions; SPEEK1−xCAx where x= 0.002,0.004, 0.006, 0.008, 0.01. The polymer electrolyte membrane is prepared by solution cast technique. The results indicate that the proton conductivity of the membranes increase with increasing solid proton conducting material. FTIR analysis shows that the cross linking reaction is performed successfully. All the results indicate that these cross-linked membranes based on SPEEK/CA show good prospect for the use as proton exchange membrane.