With a unique blend of power and energy densities, as well as long cycling lives, electrochemical supercapacitors are finding greater application in energy storage solutions. Among candidate materials for supercapacitors, MnO2 has garnered a great deal of attention. However, its low intrinsic electrical conductivity has proven to be a serious hindrance on performance when used in supercapacitor electrodes. Efficient use of conductive additives is a demonstrated, effective method to combat this problem, however there is still a great need for improvement. Two new colloidal processing techniques have been developed to mix chemically synthesized MnO2 and conductive multi-walled carbon nanotubes (MWCNT). The first strategy involved the linking of MnO2 and MWCNT through the formation of a Schiff base. 3,4-dihydroxybenzaldehyde (DB) was used to modify MnO2, while MWCNT were dispersed with the dye New Fuchsin (NF). These compounds were selected due to the presence of molecular features previously identified as conducive to strong adsorption and good colloidal dispersion, as well as the necessary functional groups required to form a Schiff base. The second involved the use of liquid-liquid extraction, primarily in an attempt to prevent post synthesis MnO2 particle agglomeration. Lauryl gallate (LG) was used as an extracting and dispersing agent for MnO2 synthesized via the reaction between aqueous potassium permanganate (KMnO4) and 1-butanol. LG facilitated the co-dispersion and mixing of both MnO2 and MWCNT in the 1-butanol phase. V2O3 was also investigated as a replacement for MnO2, as its high intrinsic electrical conductivity gives it a potential advantage over MnO2. In each of these three projects, electrodes were produced with exceptionally high areal normalized capacitances at high active mass loadings. The MnO2-MWCNT composites were used to fabricate full asymmetric supercapacitor devices that were able to deliver a useable amount of energy. / Thesis / Master of Applied Science (MASc) / The modern world has an insatiable appetite for energy and must have access to it for stationary and mobile applications. To meet this demand, it is of paramount importance to develop new, high performance energy storage technologies. The energy requirements for different applications, however, necessitate storage devices that have suitable properties. The energy stored in a large pool of hot water is not in a suitable form to power a cellphone. The key goal of this work was to further develop one particular energy storage technology, called electrochemical supercapacitors. Novel processing techniques were developed and new materials investigated with the aim of producing supercapacitor electrodes that would exceed the performance of what is already available today. The materials that were produced exhibited very high performance and offered new insight and direction for further research in this exciting field.
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/22265 |
| Date | January 2017 |
| Creators | Wallar, Cameron |
| Contributors | Zhitomirsky, Igor, Materials Science and Engineering |
| Source Sets | McMaster University |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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