title: Anion-Tunable Properties and Electrochemical Performance of Functionalized Ferrocene Compounds.
abstract: We report a series of ionically modified ferrocene compounds for hybrid lithium-organic non-aqueous redox flow batteries, based on the ferrocene/ferrocenium redox couple as the active catholyte material. Tetraalkylammonium ionic moieties were incorporated into the ferrocene structure, in order to enhance the solubility of the otherwise relatively insoluble ferrocene. The effect of various counter anions of the tetraalkylammonium ionized species appended to the ferrocene, such as bis(trifluoromethanesulfonyl)imide, hexafluorophosphate, perchlorate, tetrafluoroborate, and dicyanamide on the solubility of the ferrocene was investigated. The solution chemistry of the ferrocene species was studied, in order to understand the mechanism of solubility enhancement. Finally, the electrochemical performance of these ionized ferrocene species was evaluated and shown to have excellent cell efficiency and superior cycling stability.
authors.affiliation: Energy and Environment Directorate, Richland, WA 99352, USA.
authors.forename: Lelia
authors.initials: L
authors.lastname: Cosimbescu
authors.affiliation: Energy and Environment Directorate, Richland, WA 99352, USA.
authors.forename: Xiaoliang
authors.initials: X
authors.lastname: Wei
authors.affiliation: Fundamental and Computation Science Directorate, Richland, WA 99352, USA.
authors.forename: M
authors.initials: M
authors.lastname: Vijayakumar
authors.affiliation: Energy and Environment Directorate, Richland, WA 99352, USA.
authors.forename: Wu
authors.initials: W
authors.lastname: Xu
authors.affiliation: Fundamental and Computation Science Directorate, Richland, WA 99352, USA.
authors.forename: Monte L
authors.initials: ML
authors.lastname: Helm
authors.affiliation: Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, WA 99352, USA.
authors.forename: Sarah D
authors.initials: SD
authors.lastname: Burton
authors.affiliation: National Security Directorate, Richland, WA 99352, USA.
authors.forename: Christina M
authors.initials: CM
authors.lastname: Sorensen
authors.affiliation: Energy and Environment Directorate, Richland, WA 99352, USA.
authors.forename: Jun
authors.initials: J
authors.lastname: Liu
authors.affiliation: Energy and Environment Directorate, Richland, WA 99352, USA.
authors.forename: Vincent
authors.initials: V
authors.lastname: Sprenkle
authors.affiliation: Energy and Environment Directorate, Richland, WA 99352, USA.
authors.forename: Wei
authors.initials: W
authors.lastname: Wang