Room temperature ionic liquids with tailored physicochemical properties are promising electrolytes for numerous energy technology devices including supercapacitors, lithium batteries, and fuel cells. Understanding structure-property relationships of ionic liquids is critically important to the rational design of their electrochemical properties including ionic conductivity, diffusion, and stability of the electrical double layer of interest to the performance of energy devices. In this study, we examined the electrochemical properties of ionic liquids containing a common bis(trifluoromethylsulfonyl)imide anion ([NTf<sub>2</sub>]<sup>-</sup>) and a series of R-3-methylimidazolium cations functionalized with various R groups (table 1). In particular, we investigated the influence of ionic symmetry, chain lengths, aromatic substituents and p-p stacking interactions on the electrochemical properties of ionic liquids using cyclic voltammetry and electrochemical impedance spectroscopy. Stable potential windows, diffusion coefficients and heterogeneous electron transfer rates were evaluated in order to investigate how the physicochemical properties of each ionic liquid, such as dipole moment, viscosity and density, contribute to the overall electrochemical performance. Furthermore, supercapacitors were fabricated using two-electrode liquid cell to examine the efficiency and stability of different ionic liquids in functional devices.

Investigation of structural properties of imidazolium-based ionic liquids on redox electrochemistry

256th National Meeting (2018)

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