Electrolytes for redox flow battery systems

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dc.contributor.advisorCrouch, Andrew M.
dc.contributor.authorModiba, Portiaen_ZA
dc.contributor.otherUniversity of Stellenbosch. Faculty of Science. Dept. of Chemistry and Polymer Science.
dc.date.accessioned2010-02-23T16:28:19Zen_ZA
dc.date.accessioned2010-08-13T13:11:05Z
dc.date.available2010-02-23T16:28:19Zen_ZA
dc.date.available2010-08-13T13:11:05Z
dc.date.available2010-02-23T16:28:19Z
dc.date.issued2010-03en_ZA
dc.descriptionThesis (PhD (Chemistry and Polymer Science))--University of Stellenbosch, 2010.en_ZA
dc.description.abstractElectrochemical behaviour of Ce, Fe, Cr,V and Mn in the presence of DTPA, EDTA, EDDS, NTA ligands were investigated by using cyclic voltammetry, a rotating disc electrode and electrochemical impedance spectroscopy for use in redox flow battery (RFB) systems. RFB is currently used for energy storage, the vanadium, which is used in most of the RFB’s, however suffers from species crossover and sluggish reactions, which limit the lifetime of the battery. These various ligands and metal complexes mentioned above where all examined to identify the suitable and favoured electrolyte that can be used for a RFB system. Kinetic parameters such as potential, limiting current, transfer coefficient, diffusion coefficients, and rate constants were studied. RDE experiments confirmed that the parameters measured by CV are similar under hydrodynamic conditions and can be used to determine the kinetic parameters of the redox couples. The use of DTPA as a ligand for complexation of Ce(IV) gave more favourable results compared to other ligand with various metal complexes used in this study [1-3]. The results of kinetic studies of Ce(IV)–DTPA complex shows promise as an electrolyte for a redox flow battery. The separation of V(IV)/(V), Fe (III)/(IV),Cr(III)/(IV),Mn (III)/(IV) and Ce(III)/(IV) with various ligands (EDTA, EDDS, NTA and DTPA) were also investigated using capillary electrophoresis. To understand the speciation of these metal complexes as used in this study and particularly the vanadium, for the reason that it has a complicated (V) oxidation state. The charge/discharge performance of all electrolytes used in this work was determined and a high voltage achieved when Ce-DTPA was used, and it is compared to that of the vanadium electrolyte currently in use. This was evaluated with systems studied previously. Therefore, Ce-DTPA will be a suitable electrolyte for redox flow battery systems.en_ZA
dc.identifier.urihttp://hdl.handle.net/10019.1/3999
dc.language.isoenen_ZA
dc.publisherStellenbosch : University of Stellenbosch
dc.rights.holderUniversity of Stellenbosch
dc.subjectElectrolytesen_ZA
dc.subjectRedox flow batteryen_ZA
dc.subjectCyclic voltammetryen_ZA
dc.subjectDissertations -- Chemistryen_ZA
dc.subjectTheses -- Chemistryen_ZA
dc.subject.otherChemistry and Polymer Scienceen_ZA
dc.titleElectrolytes for redox flow battery systemsen_ZA
dc.typeThesisen_ZA
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Doctoral Degrees (Chemistry and Polymer Science)