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

Research output: Contribution to journalArticlepeer-review

4 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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