- Title
- An investigation of the reduction of molten carbonate salts for the formation of electrochemically active supercapacitor materials
- Creator
- Hughes, Matthew A.
- Relation
- University of Newcastle Research Higher Degree Thesis
- Resource Type
- thesis
- Date
- 2020
- Description
- Research Doctorate - Doctor of Philosophy (PhD)
- Description
- In this work, the relationship between the conditions of carbon deposition from molten carbonate systems and the characteristics of the produced carbons is investigated. Throughout this thesis, both physical and electrochemical analysis techniques have been used to identify variation in the morphological, structural, and electrochemical characteristics of synthesised carbons. The mechanisms and specifics of carbon growth at substrates under certain conditions, with carbon growth at a nucleating metal such as copper being identified and investigated as a special case which gives rise to unique carbon morphologies, and the trends in the variation of physical characteristics of carbons produced through molten carbonate reduction with deposition parameter variation has been explained both in terms of energy of deposition systems and, for the special case of deposition at copper, from a nucleation and growth perspective. The charge-storage characteristics of synthesised carbons has been investigated using cyclic-voltammetry (CV), step potential electrochemical spectroscopy (SPECS), and electrochemical impedance spectroscopy (EIS), and high capacitances associated with high degrees of folding and surface functionalisation have been associated with highly amorphous carbons deposited under low system energy conditions. The presence of inductive behaviour has been identified in the synthesised materials when cycled at an intermediate frequency, and this has been attributed largely to diffusion processes within the microporous structure of the materials. The synthesised carbons have been identified as consisting of a combination of graphitised and amorphous phases with varied topographies. Highly amorphous carbons with high degrees of oxygen functionalisation have been identified as superior for aqueous supercapacitor applications using CV, SPECS, and EIS, and deconvolution of the electric double layer and pseudocapacitive contributions to the total capacitive using SPECS have allowed for links to be drawn between the structure of synthesised carbons and their supercapacitive performance. The parameters of molten carbonate reduction and the cell parameters in three electrode supercapacitors have been optimised to allow for the synthesis of high performing aqueous supercapacitors, with carbons with excellent cycling stability and performances as high as 425 F g-1 being examined in 0.5 M Na₂SO₄ electrolytes.
- Subject
- electrodeposited carbon; molten carbonate electrolytes; aqueous supercapacitor; hybrid capacitor; thesis by publication
- Identifier
- http://hdl.handle.net/1959.13/1410851
- Identifier
- uon:36245
- Rights
- Copyright 2020 Matthew A. Hughes
- Language
- eng
- Full Text
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| Thumbnail | File | Description | Size | Format | |||
|---|---|---|---|---|---|---|---|
| View Details Download | ATTACHMENT01 | Thesis | 20 MB | Adobe Acrobat PDF | View Details Download | ||
| View Details Download | ATTACHMENT02 | Abstract | 252 KB | Adobe Acrobat PDF | View Details Download |