Supercapacitive performance of porous graphene nanosheets in bis(trifluoromethylsulfony)imide and bis(fluorosulfonyl)imide ionic liquid electrolytes

Bo Rui Pan, Sheng Wei Lee, Chung Jen Tseng, Chien Liang Chang, Wu Ching Hung, Jeng-Kuei Chang*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

3 Scopus citations

Abstract

A method of high-heating-rate thermal reduction is used to produce porous graphene nanosheets (PGNSs). This material is characterized by a unique holey structure, which is suitable for ionic liquid (IL) electrolyte. To study the effects of electrolyte anion, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfony)imide (EMI-TFSI) and 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (EMI-FSI) ILs are used. Due to the smaller size of FSI, EMI-FSI shows a higher conductivity and lower viscosity than those of EMI-TFSI. The specific capacitances of PGNS electrodes are 90 and 260 F g−1, respectively, measured in EMI-TFSI and EMI-FSI ILs at a potential scan rate of 50 mV s−1. The PGNS symmetric cell with EMI-FSI electrolyte is able to deliver a maximum energy and power densities of 110 Wh kg−1 and 101 kW kg−1, respectively, with a cell voltage of 3.5 V. In addition, 85% of the initial capacity can be retained after 2000 charge–discharge cycles.

Original languageEnglish
Pages (from-to)2197-2203
Number of pages7
JournalJournal of Solid State Electrochemistry
Volume22
Issue number7
DOIs
StatePublished - 1 Jul 2018

Keywords

  • Graphene electrode
  • Ionic liquid
  • Porous structure
  • Supercapacitor

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