Liquides ioniques électroactifs dans la composition d’électrolytes avancés pour des applications en énergie
This thesis contribute to the development of new electrolytes to improve the safety of lithium-ion batteries through the study and development of advanced electrolytes based on novel ionic liquids. Using newly developed synthetic approaches, several electroactive ionic liquids, which are obtained by modifying either the cation or the anion of the ionic liquid, are studied to understand how the structure of the salt’s ionic constituents affect its physico-chemical and electrochemical properties. The general methodology that guided the work throughout the whole thesis has to establish comparisons between similar ionic liquids that present the redox group on the cation and on the anion. The progress that has been made in understanding redox ionic liquids in this thesis allowed their application in several types of energy storage devices. The thesis will describe how advanced electrolytes based on these ionic liquids have been applied to prevent overcharging positive electrode materials in lithium-ion batteries, to improve safety by decreasing flammability, to increase the concentration of additives over their solubility, to increase energy density of supercapacitors and to achieve air- and moisture-stable electrochromic species for self-bleaching electrochromic devices. This thesis contributes to the field of energy storage by improving electrolytes and to the domain of ionic liquid by providing new synthesis methods, novel ion structures, and a better understanding of the fundamental of electroactive ionic liquids.
Electrochemistry Lithium ion batteries Synthesis of ionic liquids Electroactive species Concentrated electrolyte and redox shuttle