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 language | English |
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Pages (from-to) | 2197-2203 |
Number of pages | 7 |
Journal | Journal of Solid State Electrochemistry |
Volume | 22 |
Issue number | 7 |
DOIs | |
State | Published - 1 Jul 2018 |
Keywords
- Graphene electrode
- Ionic liquid
- Porous structure
- Supercapacitor