Charge transport in nonstoichiometric 2-fluoropyridinium triflate protic ionic liquids

Research output: Contribution to journalArticle

Abstract

Pyridinium triflate protic ionic liquids have been demonstrated to be highly dissociated, and nonstoichiometric compositions have been used in protic energy devices such as the all-organic proton battery. Herein, we use a combination of pulsed field gradient NMR spectroscopy and electrochemical impedance spectroscopy to investigate the charge transport properties of the nonstoichiometric protic ionic liquid 2-fluoropyridinium triflate and the variation with acid doping level. While all diffusion coefficients decreased with the amount of acid doping, the room temperature conductivity increased due to the concurrent increase in charge carrier concentration. The maximum room temperature conductivity was 7.33 mS/cm, obtained when 14% of the pyridine was protonated with triflic acid, while higher acid doping levels lead to liquid/solid mixtures with low conductivity. PEDOT supercapacitor cells with this electrolyte demonstrated very high capacitance (83.9 F/g) and charge storage capacity (23.3 mAh/g). In addition we predict that using a lower acid doping level than previously will result in superior electrolyte performance in proton batteries due to improvements in conductivity, processability and electrochemical stability.

Details

Authors
Organisations
External organisations
  • University of South Australia
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Polymer Technologies
  • Polymer Chemistry
  • Materials Chemistry
  • Physical Chemistry
Original languageEnglish
Pages (from-to)23427-23432
JournalJournal of Physical Chemistry C
Volume123
Issue number38
Publication statusPublished - 2019
Publication categoryResearch
Peer-reviewedYes