Material Development for Improved Supercapacitor and Battery-Supercapacitor Hybrid Performance
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Authors
Chamberland, Joshua P.
Date
2024-12-05
Type
thesis
Language
eng
Keyword
Energy Storage , Supercapacitor , Battery-Supercapacitor Hybrid , Graphene , Ionic Liquid , Nitroxyl Radical
Alternative Title
Abstract
In this thesis, we develop materials to improve the performance of supercapacitors and battery-supercapacitor hybrids as energy storage devices. First, process parameters used to synthesize graphene hydrogels from high-concentration aqueous graphene nanoplatelet dispersions are optimized using a design of experiments. This method produces an electrode material with a high specific surface area of 810 m2 g-1 and electrical conductivity of 2016 S m-1 which, when applied in an aqueous supercapacitor, results in volumetric capacitances more than 360% greater than a conventional graphene hydrogel electrode made from aqueous graphene oxide dispersions alone. Next, we develop a novel ionic liquid-based battery-supercapacitor hybrid that uses all three oxidation states of the organic species 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO). Usage of the ionic liquid 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIM BF4) allows for the reversible reduction of TEMPO, resulting in over 1000 charge/discharge cycles. The specific discharge capacity of the battery-supercapacitor hybrid is 226 mAh g−1 at 1 A g−1, which is almost 10 times higher than that of a comparable supercapacitor without added TEMPO. The device can operate at exceedingly high current densities of at least 50 A g-1 while still achieving 88 mAh g−1 due to the rapid kinetics of the TEMPO reactions.
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Queen's University's Thesis/Dissertation Non-Exclusive License for Deposit to QSpace and Library and Archives Canada
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Copying and Preserving Your Thesis
This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.
ProQuest PhD and Master's Theses International Dissemination Agreement
Intellectual Property Guidelines at Queen's University
Copying and Preserving Your Thesis
This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.