Holey Graphene Nanosheets with Surface Functional Groups as High-Performance Supercapacitors in Ionic-Liquid Electrolyte

Cheng Hsien Yang, Po Ling Huang, Xu Feng Luo, Chueh Han Wang, Chi Li, Yi Hsuan Wu, Jeng-Kuei Chang*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

30 Scopus citations

Abstract

Pores and surface functional groups are created on graphene nanosheets (GNSs) to improve supercapacitor properties in a butylmethylpyrrolidinium-dicyanamide (BMP-DCA) ionic liquid (IL) electrolyte. The GNS electrode exhibits an optimal capacitance of 330 F g-1 and a satisfactory rate capability within a wide potential range of 3.3 V at 25 °C. Pseudocapacitive effects are confirmed using X-ray photoelectron spectroscopy. Under the same conditions, carbon nanotube and activated carbon electrodes show capacitances of 80 and 81 F g-1, respectively. Increasing the operation temperature increases the conductivity and decreases the viscosity of the IL electrolyte, further improving cell performance. At 60 °C, a symmetric-electrode GNS supercapacitor with the IL electrolyte is able to deliver maximum energy and power densities of 140 Wh kg-1 and 52.5 kW kg-1 (based on the active material on both electrodes), respectively, which are much higher than the 20 Wh kg-1 and 17.8 kW kg-1 obtained for a control cell with a conventional organic electrolyte.

Original languageEnglish
Pages (from-to)1779-1786
Number of pages8
JournalChemSusChem
Volume8
Issue number10
DOIs
StatePublished - 11 May 2015

Keywords

  • electrochemical properties
  • graphene
  • ionic liquid
  • supercapacitors
  • surface functional groups

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