title: Biredox ionic liquids with solid-like redox density in the liquid state for high-energy supercapacitors.
abstract: Kinetics of electrochemical reactions are several orders of magnitude slower in solids than in liquids as a result of the much lower ion diffusivity. Yet, the solid state maximizes the density of redox species, which is at least two orders of magnitude lower in liquids because of solubility limitations. With regard to electrochemical energy storage devices, this leads to high-energy batteries with limited power and high-power supercapacitors with a well-known energy deficiency. For such devices the ideal system should endow the liquid state with a density of redox species close to the solid state. Here we report an approach based on biredox ionic liquids to achieve bulk-like redox density at liquid-like fast kinetics. The cation and anion of these biredox ionic liquids bear moieties that undergo very fast reversible redox reactions. As a first demonstration of their potential for high-capacity/high-rate charge storage, we used them in redox supercapacitors. These ionic liquids are able to decouple charge storage from an ion-accessible electrode surface, by storing significant charge in the pores of the electrodes, to minimize self-discharge and leakage current as a result of retaining the redox species in the pores, and to raise working voltage due to their wide electrochemical window.
authors.affiliation: Institut Charles Gerhardt Montpellier, UMR 5253, CC 1701, Université Montpellier, Place Eugène Bataillon, 34095 Montpellier Cedex 5, France.|Réseau sur le stockage electrochimique de l'énergie (RS2E), FR CNRS.
authors.forename: Eléonore
authors.initials: E
authors.lastname: Mourad
authors.affiliation: Institut Charles Gerhardt Montpellier, UMR 5253, CC 1701, Université Montpellier, Place Eugène Bataillon, 34095 Montpellier Cedex 5, France.|Réseau sur le stockage electrochimique de l'énergie (RS2E), FR CNRS.
authors.forename: Laura
authors.initials: L
authors.lastname: Coustan
authors.affiliation: Institut Charles Gerhardt Montpellier, UMR 5253, CC 1701, Université Montpellier, Place Eugène Bataillon, 34095 Montpellier Cedex 5, France.|Réseau sur le stockage electrochimique de l'énergie (RS2E), FR CNRS.
authors.forename: Pierre
authors.initials: P
authors.lastname: Lannelongue
authors.affiliation: Université Bordeaux, ISM, CNRS UMR 5255, F-33400 Talence, France.
authors.forename: Dodzi
authors.initials: D
authors.lastname: Zigah
authors.affiliation: Institut Charles Gerhardt Montpellier, UMR 5253, CC 1701, Université Montpellier, Place Eugène Bataillon, 34095 Montpellier Cedex 5, France.
authors.forename: Ahmad
authors.initials: A
authors.lastname: Mehdi
authors.affiliation: Institut Charles Gerhardt Montpellier, UMR 5253, CC 1701, Université Montpellier, Place Eugène Bataillon, 34095 Montpellier Cedex 5, France.
authors.forename: André
authors.initials: A
authors.lastname: Vioux
authors.affiliation: Institute for Chemistry and Technology of Materials, Graz University of Technology, Stremayrgasse 9, 8010 Graz, Austria.
authors.forename: Stefan A
authors.identifier: 0000-0003-2902-5319
authors.initials: SA
authors.lastname: Freunberger
authors.affiliation: Institut Charles Gerhardt Montpellier, UMR 5253, CC 1701, Université Montpellier, Place Eugène Bataillon, 34095 Montpellier Cedex 5, France.|Réseau sur le stockage electrochimique de l'énergie (RS2E), FR CNRS.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Favier
authors.affiliation: Institut Charles Gerhardt Montpellier, UMR 5253, CC 1701, Université Montpellier, Place Eugène Bataillon, 34095 Montpellier Cedex 5, France.|Réseau sur le stockage electrochimique de l'énergie (RS2E), FR CNRS.
authors.forename: Olivier
authors.initials: O
authors.lastname: Fontaine