Papers by Author: Siti Aishah Hashim Ali

Abstract: Nanocomposite polymer electrolytes were prepared by incorporating different amounts of zirconium oxide (ZrO2) nanofiller to poly(vinylidene fluoride-co-hexafluoropropylene)-lithium trifluoromethane sulfonate (PVDF-HFP-LiCF3SO3). X-ray diffraction (XRD) study has been carried out to investigate the structural features of the electrolyte films while a.c. impedance spectroscopy has been performed to investigate their electrical properties. The conductivity of nanocomposite polymer electrolyte systems is influenced by nanofiller concentration. The increase in conductivity is attributable to the increase in the fraction of amorphous region and the number of charge carriers and vice versa. The highest conductivity obtained is in the order of 10-3 S cm-1 for the system dispersed with 5 wt% of ZrO2 nanofiller.

Abstract: In the authors' laboratory, fern-like fractals have been cultured in polymer electrolyte membranes of polyethylene oxide (PEO) doped with ammonium iodide (NH4I). The simulation study was then carried out utilizing the Diffusion Limited Aggregation (DLA) based on random motion of aggregating particles modelling technique. The fractal dimension values and the forms of the simulated fractals are comparable to those observed in the PEO polymer membranes. These indicate that the simulation using the DLA model done in this study has resulted outputs that are in abidance with the original fractals cultured in the polymer membranes.

Abstract: A mathematical model for the transport in cathode of a lithium-ion cell is developed and analytical solutions to the model equations are obtained. The derived equation is tested by fitting it to published experimental discharge characteristics. Wherever possible, the values of the relevant parameters are obtained from the same literature from which the discharge characteristics were obtained. The agreement between the predicted and the experimental discharge curves are measured statistically using t-test. Since the discharge characteristics are usually plotted as voltage versus time or capacity or even state-of-discharge, hence the expression for the cell voltage has been derived.