Synthesis of aromatic and aliphatic n-heterocyclic salts and their application as organic electrolyte supporters in electrochemical capacitor

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 ([MPy]+ [BF4 ]− ), N-methylpyridinium hex-afluorophosphate ([MPy]+ [PF6 ]− ), 1,3-dibuthylimidazolium tetrafluoroborate ([DI]+ [BF4 ]− ), 1,3-dibuthylimidazolium hexafluorophosphate ([DI]+ [PF6 ]− ), 1-buthyl-4-methyl-1,2,4-triazolium tetrafluoroborate ([BMTA]+ [BF4 ]− ), and 1-buthyl-4-methyl-1,2,4-triazolium hexafluorophosphate ([BMTA]+ [PF6 ]− ). The aliphatic N-heterocyclic salts were N,N-dimethylpiperilidium tetraflu-oroborate ([DMP]+ [BF4 ]− ), N,N-dimethylpiperilidium hexafluorophosphate ([DMPy]+ [PF6 ]− ), N,N-dimethylpyrrolidium tetrafluoroborate ([DMPy]+ [BF4 ]− ) and N,N-dimethylpyrrolidium hexafluorophosphate ([DMPy]+ [PF6 ]− ), 1-ethyltriethamine tetrafluoroborate ([E-TEDA]+ [BF4 ]− ), and 1-ethyltriethamine hexafluorophosphate ([E-TEDA]+ [PF6 ]− ), respectively. We confirmed the successful synthesis of the aromatic and aliphatic N-heterocyclic chemical salts by1 H-NMR, FT-IR, and GC/MS analysis before conducting the counter-anion-exchange reactions. Then, we deter-mined 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 voltam-metry, 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.