Past Research Students

Lukhanyo Bolo

Qualification: MSc Chemistry – 2015 

Project Title: An investigation into the effects of nano-carbons on the negative electrode morphology of lead acid batteries under high rate partial state of capacity cycling. 
 
Description: The research work in the dissertation involved the investigation of improving the performance of Pb-acid batteries that was requested by a local battery manufacturer. The project focused on the fundamental understanding of the effect of carbons, and in particular nano-carbons on the reduction of the sulfation effect of the negative plate in Pb-acid batteries that was subjected to partial state of capacity cycling. The study was done in two parts: the first part was to obtain manufactured negative plates that were constructed into suitable industrial scale cells that contained the nano carbon and subjecting them to a number of electrochemical testing. The second part was to study the effect of the carbons on the material morphology of the negative plate by using Electrochemical Atomic Force Microscopy (EC-AFM) and SEM and correlating the findings of the reasons of the improved capacity cycling of the cells that contained the nano-carbons.
Charmelle Snyders
Qualification: PhD Chemistry – 2017
 
Project Title: An investigation of the morphological and electrochemical properties of spinel cathode oxide materials used in Li-ion batteries. 
 
Description: This thesis was based on the material characterization of the positive active material used in Li-ion batteries, following two synthesis routes. In her work, she investigated the phase transitions that occurred during the synthesis of a well-known cathode material used in the manufacturing of lithium-ion batteries, namely the doped manganese oxide spinel. By using in-situ temperature powder x-ray diffraction as well as thermal gravimetric analysis, the phase modifications as the material changes from a typical amorphous gel to a crystalline electrochemical active material by using full pattern rietveld refinement of the diffractograms. The active phases had already formed at a much lower temperature to what was reported in literature with a significantly smaller crystallite size. Subsequently she showed that the aqueous phase of the material could be continuously spray-dried at a relatively low temperature to form nano-based particles of the electro-active material when compared to the conventional batch process material. 
Brandon Davoren
Qualification: MSc Chemistry – 2017
 
Project Title: Tribocorrosion Properties of Friction Stir Welded and Laser Welded Titanium Alloy.
 
Description: The research work described in the dissertation was about an investigation in using tribocorrosion to possibly differentiate between the weld zone and the parent material. Tribocorrosion is the combination of the fields of tribology and electrochemical corrosion to study the effect on the surfaces of a welded titanium alloy. The study was done in collaboration with eNtsa in the faculty of mechanical engineering who supplied the samples as well as the use of their tribometer. The samples used in the study was a titanium based alloy known as Ti6Al4V which was subjected to friction stir welding and laser welding processes. The welding process induces different material properties onto the surface of the sample, and in this study, the effect it has on the material’s corrosion properties.  
Zippo Madikane
Qualification: MSc Chemistry - 2018

Project title: Electrospinning of carbon nanofibers for the investigation of the behavior of lead electrodeposits on the carbon surface

Description: When the lead-acid battery is being discharged, the positive active material PbO₂ and the negative active material Pb reacts with the electrolyte H₂SO₄ leading to the formation of PbSO₄ and H₂O. The formed PbSO₄ (insulator) is changed back into its original state of PbO₂ and Pb (metallic) when the battery is recharged. As the battery is charged, there are larger particles of PbSO₄ that remain unconverted, in particular the negative electrode and thereby reducing its performance, especially in terms of the charge acceptance of the battery. The study looked at improving the performance of the battery by adding carbon nanofibers into the manufacturing of negative plate thereby improving the surface area and  conductivity of plate during capacity cycling. The nanofibers were made by electrospinning technique where the source of carbon used are conductive polymers such as polyaniline, polyacrylonitrile and polypyrole with the addition of primarily sugar based compounds.
Nomasonto Rapulenyane
Qualification: PhD Chemistry – 2018

Project title: Development of high capacity lithium-manganese-rich cathode materials xLi2MnO3•(1-x)LiMn0.5Ni0.5O2 for lithium ion batteries

Description: 

The research work of this study was in collaboration with the CSIR in Pretoria. The project looked at developing a synthesis method to produce layered cathode materials that have the formula xLi2MnO3•(1-x)LiMO2 (M= Ni and Mn) that are used in lithium ion batteries. The prepared materials were shown to be made using a simpler one pot synthesis route and would display high capacity of above 200 mAh/g within a voltage range of 2.0 V to 4.8 V. The project made use of number of experimental techniques such as powder x-ray diffraction and x-ray photoelectron spectroscopy to highlight the structural and physical properties of the materials synthesized under different conditions. Aspects of the research work were published in a journal article https://doi.org/10.1016/j.jallcom.2018.05.207 and filed as local patents.

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