###### Abstract  
Aromatic and aliphatic N-heterocyclic chemical salts were synthesized by counter-anion-exchange reactions after substitution reactions in order to apply them as organic electrolyte supporters in an electrochemical capacitor (super capacitor). The aromatic N-heterocyclic salts were N-methylpyridinium tetrafluoroborate ([IMPy]\({}^{+}\)[BF\({}_{4}\)]\({}^{-}\)), N-methylpyridinium hexafluorophosphate ([MPy]\({}^{+}\)[PF\({}_{6}\)]\({}^{-}\)), 1,3-dibutylimidazolium tetrafluoroborate ([DI]\({}^{+}\)[BF\({}_{4}\)]\({}^{-}\)), 1,3-dibutylimidazolium hexafluorophosphate ([DI]\({}^{+}\)[PF\({}_{6}\)]\({}^{-}\)), 1,1-butyl-4-methyl-1,2,4-triazolium tetrafluoroborate ([BMTA]\({}^{+}\)[BF\({}_{4}\)]\({}^{-}\)), and 1-butyl-4-methyl-1,2,4-triazolium hexafluorophosphate ([BMTA]\({}^{+}\)[PF\({}_{6}\)]\({}^{-}\)). The aliphatic N-heterocyclic salts were N,N-dimethylpiperidium tetrafluoroborate ([DMP]\({}^{+}\)[BF\({}_{4}\)]\({}^{-}\)), N,N-dimethylpiperillium hexafluorophosphate ([DMPy]\({}^{+}\)[PF\({}_{6}\)]\({}^{-}\)), N,N-dimethylply pyrrolium tetrafluoroborate ([DMPy]\({}^{+}\)[PF\({}_{6}\)]\({}^{-}\)) and N,N-dimethylpyrrolidin hexafluorophosphate ([DMPy]\({}^{+}\)[PF\({}_{6}\)]\({}^{-}\)), 1-ethyltriethamine tetrafluoroborate ([E-TEDA]\({}^{+}\)[BF\({}_{4}\)]\({}^{-}\)), and 1-ethyltriethamine hexafluorophosphate ([E-TEDA]\({}^{+}\)[PF\({}_{6}\)]\({}^{-}\)), respectively. We confirmed the successful synthesis of the aromatic and aliphatic N-heterocyclic chemical salts by \({}^{1}\)H-NMR, FT-IR, and GC/MS analysis before conducting the counter-anion-exchange reactions. Then, we determined the electrochemical potential of vanadium acetylacetonate (V(acac)\({}_{3}\)) under acetonitrile in the presence of the N-heterocyclic chemical salts as energy-storage chemicals. By cyclic voltammetry, the maximum voltages with the N-heterocyclic chemical salts in acetonitrile reached 2.2 V under a fixed current value. Charge-discharge experiments were performed in the electrochemical capacitor with an anion-exchange membrane using a non-aqueous electrolyte prepared with a synthesized N-heterocyclic salt in acetonitrile. vanadium electrochemical capacitor; N-heterocyclic aromatic salts; N-heterocyclic aliphatic salts; vanadium acetylacetonate; energy-storage chemicals; counter-anion-exchange reaction +
Footnote †: journal: Applied Sci. to power and energy loss. Another problem of the aqueous electrochemical capacitor system is the low cell potential because of the aqueous electrolyte solutions [14]. On the other hand, non-aqueous systems exhibit wide potential windows and a wide temperature range compared with aqueous systems because of the physical and chemical properties of the non-aqueous electrolyte solution [15]. Despite the advantages of a non-aqueous electrolyte solution in the electrochemical capacitor, there have been few studies of this setup because of the difficulties in synthesizing the organic electrolyte, the low solubility of vanadium salts as energy-storage materials, and the physical problem of the membrane for ion exchange during the charge-discharge process under a non-aqueous electrochemical capacitor. To solve the above-mentioned problems, this study synthesized the N-heterocyclic chemical salts [MPy]\({}^{+}\)[BF\({}_{4}\)]\({}^{-}\), [MPy]\({}^{+}\)[PF\({}_{6}\)]\({}^{-}\), [DI]\({}^{+}\)[BF\({}_{4}\)]\({}^{-}\), [DI]\({}^{+}\)[PF\({}_{6}\)]\({}^{-}\), [BMTA]\({}^{+}\)[BF\({}_{4}\)]\({}^{-}\), [BMTA]\({}^{+}\)[PF\({}_{6}\)]\({}^{-}\), [DMP]\({}^{+}\)[BF\({}_{4}\)]\({}^{-}\), [DMP]\({}^{+}\)[PF\({}_{6}\)]\({}^{-}\), [DMPy]\({}^{+}\)[BF\({}_{4}\)]\({}^{-}\), [DMPy]\({}^{+}\)[PF\({}_{6}\)]\({}^{-}\), [E-TEDA]\({}^{+}\)[BF\({}_{4}\)]\({}^{-}\), and [E-TEDA]\({}^{+}\)[PF\({}_{6}\)]\({}^{-}\) through counter-anion-exchange reactions after the SN2 reaction. Proton nuclear magnetic resonance (\({}^{1}\)H-NMR), Fourier transform infrared (FT-IR), and gas chromatography with mass spectrometry (GC/MS) were used to confirm the synthesized products during the reaction.