Supercapacitive Properties of Micropore- and Mesopore-Rich Activated Carbon in Ionic-Liquid Electrolytes with Various Constituent Ions

Quoc Dat Nguyen, Jagabandhu Patra, Chien Te Hsieh, Jianlin Li, Quan Feng Dong, Jeng-Kuei Chang*

*Corresponding author for this work

Research output: Contribution to journalArticle

4 Scopus citations

Abstract

Ionic-liquid (IL) electrolytes, characterized by large potential windows, intrinsic ionic conductivity, low environmental hazard, and high safety, are used for micropore- and mesopore-rich activated-carbon (AC micro and AC meso ) supercapacitors. IL electrolytes consisting of various cations [1-ethyl-3-methylimidazolium (EMI + ), N-propyl-N-methylpyrrolidinium (PMP + ), and N-butyl-N-methylpyrrolidinium (BMP + )] and various anions [bis(trifluoromethylsulfonyl)imide (TFSI ), BF 4 , and bis(fluorosulfonyl)imide (FSI )] are investigated. The electrolyte conductivity, viscosity, and ion transport properties at the AC micro and AC meso electrodes are studied. In addition, the capacitance, rate capability, and cycling stability of the two types of AC electrodes are systematically examined and post-mortem material analyses are conducted. The effects of IL composition on the charge–discharge capacitances of the AC micro electrodes are more pronounced than those for the AC meso electrodes. The FSI-based IL electrolytes, for which electrochemical properties are cation dependent, are found to be promising. Incorporating EMI + with FSI results in a low electrolyte viscosity and a fast ion transport, giving rise to optimized electrode capacitance and rate capability. Replacing EMI + with PMP + increases the cell voltage (to 3.5 V) and maximum energy density (to 42 Wh kg −1 ) of the AC micro cell at the cost of cycling stability.

Original languageEnglish
Pages (from-to)449-456
Number of pages8
JournalChemSusChem
Volume12
Issue number2
DOIs
StatePublished - 24 Jan 2019

Keywords

  • carbon
  • electric double-layer
  • ionic liquids
  • pore size
  • supercapacitors

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