Bivalent cations conductive solid ionogel electrolytes for metal-ion applications /
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(Published version)
Date
2023
Authors
Demarthe, Nicolas
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thesis
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Abstract
The development of all-solid-state energy storage devices calls for the use of new, innovative materials including electrolytes. These must be competitive with commercial liquid electrolytes in terms of ionic conductivity and electrochemical stability. Ionics liquids (ILs) are already used for their interesting properties such as very low vapour pressure, low melting point, non-flammability, and wide electrochemical windows. Nevertheless, they remain liquid and present leakage and therefore packaging problems. The confinement of ionic liquids in polyvinylidene fluoride polymer (ionogels) limits the risk of thermal runaway in electrochemical devices. These are biphasic materials with continuous interfaces between an ionic liquid and the solid matrix (silica or polymer) that confines it. Ionogels feature very high ionic conductivity. By adding Li, Mg or Zn salts to IL, ionogels can be tailored to specific applications such as supercapacitors and batteries. The switch from monovalent to bivalent cations guarantees a higher theoretical energy density in the device. The present work focuses on the interactions and mobility of ions in ionogels. We are studying the competitive coulombic interactions either between the cation of interest (Li+/Mg2+/Zn2+) and the IL anion or with the confining solid matrix. These studies shed light on the surprising diffusivity of these cations in ionogels. The chemical and physical properties of the polymer play an essential role in these diffusion mechanisms at the solid-liquid interface. Confinement allows the cations of interest to select a preferred interaction with the host polymer, with a possible hopping diffusion mechanism at the continuous interface. Finally, ionogels designed for prototype metal-ion hybrid supercapacitors can be studied in symmetrical cells to confirm that transport properties are better in highly concentrated ionogels than in the ionic liquids themselves.
School/Discipline
University of South Australia. UniSA STEM.
UniSA STEM
UniSA STEM
Dissertation Note
Thesis (PhD(Nantes University and the University of South Australia))--University of South Australia, 2023.
Provenance
Copyright 2023 Nicolas Demarthe.
Description
In English with some French
1 ethesis (165 pages) :
colour illustrations, charts (chiefly colour)
Includes bibliographical references
1 ethesis (165 pages) :
colour illustrations, charts (chiefly colour)
Includes bibliographical references
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506 0#$fstar $2Unrestricted online access