Browsing by Author "Nurul Hayati Idris"

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    Advanced materials for lithium rechargeable battery
    (University of Wollongong (Degree of Doctor of Philosophy), 2011) Nurul Hayati Idris
    Due to the rapid increase in the use of portable computers, mobile phones, and electric vehicles, there is an increasing demand for larger capacity, smaller size, lighter weight and lower priced rechargeable batteries. Lithium ion battery technology offers the highest energy densities by weight of all the commercial rechargeable battery technologies, with high voltage, long cycle life, and a wide environmental operation range.
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    Comparison on electrochemical performances of LiNi0.5Mn1.5O4 cathode materials synthesized using different precursors
    (Materials Today: Proceedings, 2015) Nabilah Mokhtar; Nurul Hayati Idris
    In this work, LiNi0.5Mn1.5O4 has been synthesized by using acetate and carbonate precursors, respectively and ball-milled with citric acid, followed by heat treatment at high temperature. The structure, morphology and electrochemical performances of all samples were investigated using X-ray diffraction, scanning electron microscope, and galvanostatic testing. The high crystallinity and small particle size are affected by the homogeneity of the samples with the presence of citric acid. It was shown that the electrochemical performances of LiNi0.5Mn1.5O4 prepared from acetate precursor exhibit the highest discharge capacity of 120 mAh g-1 at 1 C rate.
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    Enhanced capacitance of hybrid layered graphene/nickel nanocomposite for supercapacitors
    (Scientific Reports, 2016) Norsaadatul Akmal Mohd Zaid; Nurul Hayati Idris
    In this work, Ni nanoparticles were directly decorated on graphene (G) nanosheets via mechanical ball milling. Based on transmission electron microscopy observations, the Ni nanoparticles were well dispersed and attached to the G nanosheet without any agglomerations. Electrochemical results showed that the capacitance of a G/Ni nanocomposite was 275 F g−1 at a current density of 2 A g−1, which is higher than the capacitance of bare G (145 F g−1) and bare Ni (3 F g−1). The G/Ni electrode also showed superior performance at a high current density, exhibiting a capacitance of 190 F g−1 at a current density of 5 A g−1 and a capacitance of 144 F g−1 at a current density of 10 A g−1. The equivalent series resistance for G/Ni nanocomposites also decreased. The enhanced performance of this hybrid supercapacitor is best described by the synergistic effect, i.e. dual charge-storage mechanism, which is demonstrated by electrical double layer and pseudocapacitance materials. Moreover, a high specific surface area and electrical conductivity of the materials enhanced the capacitance. These results indicate that the G/Ni nanocomposite is a potential supercapacitor.