This thesis contains the research performed on novel magnetically ordered pseudocapacitive materials (MOPCs) which display interesting and unique capacitive properties. These properties are a result of the strong magneto-capacitive and magneto-electric coupling characteristics that MOPC materials possess at room temperature. The purpose of this research is to investigate the unique capacitive properties of NiFe2O4 (NFO) and SrFe12O19(SFO) by examining the effects that the high energy ball milling procedure, the addition of a charge transfer mediation and biomimetic dispersing agent called gallocyanine dye, and the formation of composite electrodes at varying mass ratios with pseudocapacitive conducting polypyrrole polymer have on the capacitance of NFO and SFO. / The enhanced cycle stability, cycle lifetime, capacitance retention, and power densities of electrochemical capacitors make them an increasingly attractive option for modern energy storage needs, including grid level energy storage systems, mobile electronics, heavy construction equipment, military communication devices, power tools, public transportation, electric vehicles and capacitive water deionization systems to name a few. Recently, materials that displayed magnetoelectric coupling phenomena leading to enhanced magneto-capacitive properties are of particular interest, specifically ferrimagnetic spinels and hexagonal ferrites. This thesis is aimed at improving the capacitive performance of NiFe2O4 (NFO) and SrFe12O19 (SFO) based magnetically ordered pseudocapacitor electrodes by elucidating the effects of various nanomaterials preparation techniques on capacitance. The nanomaterials preparation techniques explored in this body of work include the addition of biomimetic dispersing agents, application of high energy ball milling, and forming composites using n-doped conducting pseudocapacitive polypyrrole polymers. Project 1 explored how the addition of gallocyanine dye (GCD) dispersing agent affects the capacitance of NFO. Additionally, the effects of the high energy ball milling (HEBM) process on capacitance were explored and these results were combined with the optimized gallocyanine dye results. Lastly NFO composites with Tiron-doped PPy were prepared at varying mass ratios and combined with optimized HEBM results to achieve the best capacitance results. Project 2 utilized the optimized GCD mass ratios with HEBM to enhance the capacitance of SFO. Tiron doped PPy was used with HEBM SFO at varying mass ratios to achieve the best performing composite electrode. Lastly, the best electrode composition from project 2 was used as anode in an aqueous asymmetric cell using MnO2 as the cathode, proving to be a viable anode chemistry in practical electrochemical capacitor applications. / Thesis / Master of Applied Science (MASc) / The global power demand has been increasing rapidly since the advent of the industrial era, unfortunately human civilization has mostly relied upon fossil fuels to provide the necessary energy for the function of society resulting in vast quantities of greenhouse gases being released into the atmosphere, having a global warming effect on the planet. Recently renewable energy production technologies have been developed but many are intermittent in nature and require efficient energy storage devices to properly hold that energy. Additionally, with countless industries requiring varying quantities of energy or power, the solution for adequate energy storage is a complex multifaceted one that cannot be solved by one energy storage technology alone. For this reason, additional energy storage technology must be developed. The main goal of this work is to develop electrochemical capacitor (ECs) technology, an energy storage solution with greater capacitance retention, cycle stability and cycle lifetime attributes at high charge-discharge rates relative to current battery technology, meaning that ECs can outperform batteries in high power demand applications such as; regenerative breaking, hand-held power tools, heavy construction equipment and even the large energy fluctuations associated with grid level energy storage. Materials with novel magnetic properties were explored to be developed for high active mass loaded electrodes using advanced nano-materials preparation techniques to enhance capacitance. Doing so increased the performance of these energy storage devices drastically, overcoming the poor intercalation attributes associated with high active mass loaded electrodes, making them viable for practical energy storage applications.
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/30396 |
| Date | January 2024 |
| Creators | MacDonald, Michael |
| Contributors | Zhitomirsky, Igor, Materials Science and Engineering |
| Source Sets | McMaster University |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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