Browsing by Author "Willenberg, Shane"

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    Carbon supported aluminium trifluoride nanoparticles functionalized lithium manganese oxide for the development of advanced lithium ion battery system
    (University of the Western Cape, 2017) Willenberg, Shane; Ross, Natasha
    A novel lithium ion (Li-ion) battery cathode material has been investigated for potential mobile technology energy storage applications. I have successfully synthesized Lithium Manganese oxide (LMO), reduced Graphene Oxide (rGO) and Aluminium trifluoride (AlF3). The cathode coated nanocomposite was compiled of the aforementioned materials to give [AlF3LiMn2O4-rGO]. A single-phase spinel was observed from X-ray diffraction (XRD) studies with a high intensity (111) plane which indicates good electrochemical activity. No alterations to the crystal structure were observed after forming the composite nano-cathode material. Fourier transfer infrared (FTIR) spectroscopy showed the vibrational spectrum of LiMn2O4 with a with asymmetric MnO6 stretching confirming that the spinel was formed.
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    Electrochemical analysis of architecturally enhanced LiFe0.5Mn0.5PO4 multiwalled carbon nanotube composite
    (Hindawi, 2021) Sifuba, Sabelo; Willenberg, Shane; Feleni, Usisipho
    In this work, the effect of carbon on the electrochemical properties of multiwalled carbon nanotube (MWCNT) functionalized lithium iron manganese phosphate was studied. In an attempt to provide insight into the structural and electronic properties of optimized electrode materials, a systematic study based on a combination of structural and spectroscopic techniques was conducted. The phosphor-olivine LiFe0.5Mn0.5PO4 was synthesized via a simple microwave synthesis using LiFePO4 and LiMnPO4 as precursors. Cyclic voltammetry was used to evaluate the electrochemical parameters (electron transfer and ionic diffusivity) of the LiFe0.5Mn0.5PO4 redox couples. The redox potentials show two separate distinct redox peaks that correspond to Mn2+/Mn3+ (4.1 V vs Li/Li+) and Fe2+/Fe3+ (3.5 V vs Li/Li+) due to interaction arrangement of Fe-O-Mn in the olivine lattice. The electrochemical impedance spectroscopy (EIS) results showed LiFe0.5Mn0.5PO4-MWCNTs have high conductivity with reduced charge resistance. This result demonstrates that MWCNTs stimulate faster electron transfer and stability for the LiFe0.5Mn0.5PO4 framework, which demonstrates to be favorable as a host material for Li+ ions.
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    Spectroscopic and electrochemical exploration of carbon-infused intercalation-type spinel composite for aqueous systems
    (Frontiers Media, 2022) Willenberg, Shane; Carleschi, Emanuela; Ross, Natasha
    Lithium-manganese-based compounds are promising intercalation host materials for aqueous battery systems due to their synergy with high ionic conductive aqueous electrolytes, safety, eco-friendliness, and low cost. Yet, due to poor electrical conductivity and trapping of diffused electrolyte cations within its crystal formation, achieving optimum cycle stability and rate capability remains a challenge. This unfortunately limits their use in modern day high-powered devices, which require quality output with high reliability. Here, the authors propose a facile method to produce LiMn2O4 and LiFe0.5Mn0.5PO4 and compare their structural stability and corresponding electrochemical performance by controlling the interfacial layer through multi-walled carbon nanotubes’ (MWCNTs) infusion.