Abstract
Electrolytes are at the heart of batteries and supercapacitors and their primary role is to conduct ions, and even if their specifications are actually more complex: chemical stability, high cell voltage, high conductivity. However, depending on the design of the molecules that compose the cation and/or anion, their function could be expanded. Ionic liquids are particularly suitable for this functionalization because of their interesting properties as an electrolyte and their ease of synthesis.In the field of supercapacitors, energy density is a technological limitation. To address this, an innovative strategy is the addition of redox molecules to the electrolyte to participate in charge storage. Despite the promise to increase energy densities (or apparent capacities), the use of redox electrolyte faces two clearly identified limitations: (1) the diffusion of redox molecules decreases the coulombic efficiency and (2) the self-discharge is important. One of these possibilities is the use of biredox ionic liquids (2 oxidation-reducing pairs). This thesis work focused on the study of electrolyte dynamics based on redox ionic liquids for supercapacitor application. The effect of the confinement of redox electrolytes in the porosity of carbon electrodes has been studied. Thanks to this, the different interactions as diffusion and adsorption between redox ionic liquids and electrodes are described. The formalism used to understand these different electrochemical dynamics allow us to combine theory and experimentation to go ever further in understanding the interactions of redox ionic liquids as an electrolyte for energy storage.