Effect of activated carbon xerogel pore size on the capacitance performance of ionic liquid electrolytes

Fiona. B. Sillars, S. Isobel Fletcher, Mojtaba Mirzaeian, Peter J. Hall

Research output: Contribution to journalArticle

Abstract

The use of ionic liquid (IL) electrolytes promises to improve the energy density of electrochemical capacitors (ECs) by allowing for operation at higher voltages. Several studies have also shown that the pore size distribution of materials used to produce electrodes is an important factor in determining EC performance. In this research the capacitative, energy and power performance of ILs 1-ethyl-3-methylimidazolium tetrafluoroborate (EMImBF4), 1-ethyl-3-methylimidazolium dicyanamide (EMImN(CN)2), 1,2-dimethyl-3-propylimidazolium bis(trifluoromethylsulfonyl)imide (DMPImTFSI), and 1-butyl-3-methylpyrrolidinium tris(pentafluoroethyl)trifluorophosphate (BMPyT(F5Et)PF3) were studied and compared with the commercially utilised organic electrolyte 1 M tetraethylammonium tetrafluoroborate solution in anhydrous propylene carbonate (Et4NBF4-PC 1 M). To assess the effect of pore size on IL performance, controlled porosity carbons were produced from phenolic resins activated in CO2. The carbon samples were characterised by nitrogen adsorption-desorption at 77 K and the relevant electrochemical behaviour was characterised by cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy. The best capacitance performance was obtained for the activated carbon xerogel with average pore diameter 3.5 nm, whereas the optimum rate performance was obtained for the activated carbon xerogel with average pore diameter 6 nm. When combined in an EC with IL electrolyte EMImBF4 a specific capacitance of 210 F g-1 was obtained for activated carbon sample with average pore diameter 3.5 nm at an operating voltage of 3 V. The activated carbon sample with average pore diameter 6 nm allowed for maximum capacitance retention of approximately 70% at 64 mA cm-2.
Original languageEnglish
Pages (from-to)695-706
Number of pages12
JournalEnergy & Environmental Science
Volume4
Issue number3
DOIs
Publication statusPublished - 2011
Externally publishedYes

Fingerprint

Ionic Liquids
Xerogels
Ionic liquids
Activated carbon
electrolyte
Electrolytes
Pore size
activated carbon
Capacitance
Capacitors
Carbon
Imides
Phenolic resins
Tetraethylammonium
carbon
Electric potential
Electrochemical impedance spectroscopy
Interleukin-1
Cyclic voltammetry
Propylene

Cite this

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abstract = "The use of ionic liquid (IL) electrolytes promises to improve the energy density of electrochemical capacitors (ECs) by allowing for operation at higher voltages. Several studies have also shown that the pore size distribution of materials used to produce electrodes is an important factor in determining EC performance. In this research the capacitative, energy and power performance of ILs 1-ethyl-3-methylimidazolium tetrafluoroborate (EMImBF4), 1-ethyl-3-methylimidazolium dicyanamide (EMImN(CN)2), 1,2-dimethyl-3-propylimidazolium bis(trifluoromethylsulfonyl)imide (DMPImTFSI), and 1-butyl-3-methylpyrrolidinium tris(pentafluoroethyl)trifluorophosphate (BMPyT(F5Et)PF3) were studied and compared with the commercially utilised organic electrolyte 1 M tetraethylammonium tetrafluoroborate solution in anhydrous propylene carbonate (Et4NBF4-PC 1 M). To assess the effect of pore size on IL performance, controlled porosity carbons were produced from phenolic resins activated in CO2. The carbon samples were characterised by nitrogen adsorption-desorption at 77 K and the relevant electrochemical behaviour was characterised by cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy. The best capacitance performance was obtained for the activated carbon xerogel with average pore diameter 3.5 nm, whereas the optimum rate performance was obtained for the activated carbon xerogel with average pore diameter 6 nm. When combined in an EC with IL electrolyte EMImBF4 a specific capacitance of 210 F g-1 was obtained for activated carbon sample with average pore diameter 3.5 nm at an operating voltage of 3 V. The activated carbon sample with average pore diameter 6 nm allowed for maximum capacitance retention of approximately 70{\%} at 64 mA cm-2.",
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Effect of activated carbon xerogel pore size on the capacitance performance of ionic liquid electrolytes. / Sillars, Fiona. B.; Fletcher, S. Isobel; Mirzaeian, Mojtaba; Hall, Peter J.

In: Energy & Environmental Science, Vol. 4, No. 3, 2011, p. 695-706.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Effect of activated carbon xerogel pore size on the capacitance performance of ionic liquid electrolytes

AU - Sillars, Fiona. B.

AU - Fletcher, S. Isobel

AU - Mirzaeian, Mojtaba

AU - Hall, Peter J.

PY - 2011

Y1 - 2011

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AB - The use of ionic liquid (IL) electrolytes promises to improve the energy density of electrochemical capacitors (ECs) by allowing for operation at higher voltages. Several studies have also shown that the pore size distribution of materials used to produce electrodes is an important factor in determining EC performance. In this research the capacitative, energy and power performance of ILs 1-ethyl-3-methylimidazolium tetrafluoroborate (EMImBF4), 1-ethyl-3-methylimidazolium dicyanamide (EMImN(CN)2), 1,2-dimethyl-3-propylimidazolium bis(trifluoromethylsulfonyl)imide (DMPImTFSI), and 1-butyl-3-methylpyrrolidinium tris(pentafluoroethyl)trifluorophosphate (BMPyT(F5Et)PF3) were studied and compared with the commercially utilised organic electrolyte 1 M tetraethylammonium tetrafluoroborate solution in anhydrous propylene carbonate (Et4NBF4-PC 1 M). To assess the effect of pore size on IL performance, controlled porosity carbons were produced from phenolic resins activated in CO2. The carbon samples were characterised by nitrogen adsorption-desorption at 77 K and the relevant electrochemical behaviour was characterised by cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy. The best capacitance performance was obtained for the activated carbon xerogel with average pore diameter 3.5 nm, whereas the optimum rate performance was obtained for the activated carbon xerogel with average pore diameter 6 nm. When combined in an EC with IL electrolyte EMImBF4 a specific capacitance of 210 F g-1 was obtained for activated carbon sample with average pore diameter 3.5 nm at an operating voltage of 3 V. The activated carbon sample with average pore diameter 6 nm allowed for maximum capacitance retention of approximately 70% at 64 mA cm-2.

U2 - 10.1039/C0EE00337A

DO - 10.1039/C0EE00337A

M3 - Article

VL - 4

SP - 695

EP - 706

JO - Energy & Environmental Science

JF - Energy & Environmental Science

SN - 1754-5706

IS - 3

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