Muhd Zu Azhan Yahya

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.

Effect of pressure on structural, electronic and elastic properties of cubic (Pm3m) SnTiO 3 using first principle calculation

The electronic band structure, density of state and elastic properties of lead-free perovskite oxide SnTiO3 (ST) were investigated by employing first principles calculation using the Density Functional Theory (DFT) within local density approximation (LDA). The energy band gap was calculated from the separation between the Ti 3d (conduction band) and the maximum of O 2p (valence band). This gives an indirect band gap of 2.36 eV. The elastic constants and their pressure dependence were calculated up to 30 GPa and the independent elastic constants (C11, C12, and C44), bulk modules, B were obtained and analyzed. The results showed that SnTiO3 have a mechanical stability in cubic phase (Pm3m).

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.

First Principle Study of Dynamical Properties of a New Perovskite Material Based on GeTiO3

The dynamical properties of a new perovskite GeTiO3 materials have been investigated by using first principle calculation based on Density Functional Theory (DFT) within the gradient generalized approximation (GGA). All calculations were performed using the Cambridge Serial Total Energy Package (CASTEP) computer code. The calculations include the structural parameter, Born effective charges, and phonon dispersion. The calculated Born effective charges and phonon dispersion have been analyzed and the possibility of ferroelectric feature in GeTiO3 compounds has been discussed. From the analysis, the calculated Born effective charge ZGe and ZTi showed large anomaly compared to the nominal charge which contributed to the large atomic displacement. The calculated phonon dispersion showed the most unstable mode was at G point and the unstable modes were dominated by Ge branch. The dynamical properties and ferroelectric properties in GeTiO3 are discussed and compared with the ferroelectric feature in PbTiO3.

Conductivity studies on cellulose acetate–ammonium tetrafluoroborate based polymer electrolytes

Abstract In this work, cellulose acetate was doped, with ammonium tetrafluoroborate as doping salt, to form polymer electrolytes. Further enhancement in conductivity was carried out by plasticising the salted polymer electrolytes with polyethylene glycols (polyethylene glycol 600). The ionic conductivity σ of the films was determined using electrochemical impedance spectroscopy. The highest σ obtained for the cellulose acetate–ammonium tetrafluoroborate film was 2·18×10−7 S cm−1 and enhanced to 1·41×10−5 S cm−1 with the addition of 30 wt-% polyethylene glycol 600. The data were then analysed using complex permittivity ϵ* and complex electrical modulus formalism M* for the highest conductivity unplasticised and plasticised samples at various temperatures. The temperature dependent conductivity data obey the Arrhenius relationship. The polymer–salt complexation has also been confirmed by attenuated total reflectance Fourier transform infrared spectral studies.

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.

Investigation on effects of substituents in N,N′-dibensylidene ethane-1,2-diamine towards corrosion inhibition on steel in 1M HCl

Abstract Schiff base compounds, namely, N,N′-dibensylideneethane-1,2-diamine (baen), N,N′-bis(4-chlorobenzylidene)ethane-1,2-diamine (cbaen), N,N′-bis(4-methyl benzylidene)ethane-1,2-diamine (mbaen) and 4-(((2-4-hydroxybenzylidene amino)ethylimino) methyl)phenol (hbaen) were tested as corrosion inhibitors on mild steel in 1M HCl via polarisation method. These compounds were synthesised from the corresponding substituted benzaldehydes and ethylenediamine. Results indicate that the presence of chloro, methyl and hydroxyl substituents enhance the inhibitive properties of N,N′-dibensylideneethane-1,2-diamine. Cbaen achieved the highest inhibition efficiency of 80·76% at 1 × 10–3 M.

Frequency dependent conductivity studies on PMMA–LiCF3SO3 polymer electrolytes

Abstract Polymer electrolytes composed of poly(methylmethacrylate) as a host polymer and lithium triflate as a salt have been prepared by solution cast technique. Polymer salt complexation has been confirmed by attenuated total reflectance Fourier transform infrared spectral studies. The ac conductivity as a function of temperatures in the frequency range 100 Hz–1 MHz has been carried out. The conductivity–temperature plots found follows the Arrhenius rule. The complex permittivity ϵ* and complex electric modulus M* have been analysed. The dispersion observe at low frequency is due to the space charge effect arising from the electrodes. The modulus spectra reveal that the dispersion deviates from the Debye behaviour. The ionic conductivity relaxation is determined from the maximum of the peaks of the dielectric loss modulus associated with the ac activation energy for ion relaxation E fp=0·337 eV, which agrees well with the dc conduction activation energy E A=0·341 eV. Thus, it is suggested that the dynamic mechanism for the ionic conduction is achieved at the same energy barrier while conducting as well as relaxing.

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.