Fluorine‐Free Biomass‐Derived Ionic Liquid Electrolytes: Ion Dynamics and Electrochemical Properties

Here we present the synthesis, physical characterization, and transport as well as electrochemical properties of a novel class of ten ionic liquids (ILs) derived from biomass. Two biomass derived anions such as furan‐2‐carboxylate [FuA] and tetrahydrofuran‐2‐carboxylate [HFuA] are coupled to a range of nitrogen heterocyclic cations to create the ILs, for which the nature of cation controlled their properties. For instance, the thermal decomposition temperature ranges from 183 to 259 °C, the glass transition temperature from − 47 to − 70 °C, and the ionic conductivity from 0.002 to 1.4 mS cm −1 at 20 °C. The supercapacitors prepared using [EPy][FuA] and [EMPip][FuA] exhibited specific capacitances of 99 F g −1 and 70 F g −1 at 0.2 A g −1 , respectively. The [EPy][FuA]‐based supercapacitor achieved an energy density of 56 Wh kg −1 as well as a power density of 410 W kg −1 at 0.2 A g −1 , while the [EMPip][FuA]‐based supercapacitor achieved an energy density of 36 Wh kg −1 and a power density of 360 W kg −1 at 0.2 A g −1 . In addition, the supercapacitors retained 98% and 94% of their initial capacitances after 6000 cycles, for [EPy][FuA] and [EMPip][FuA] electrolytes, respectively.