title: Holey graphene nanosheets with surface functional groups as high-performance supercapacitors in ionic-liquid electrolyte.
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.
authors.affiliation: Institute of Materials Science and Engineering, National Central University, 300 Jhong-Da Road, Taoyuan (Taiwan), Fax: (+886) 3-2805034.
authors.forename: Cheng-Hsien
authors.initials: CH
authors.lastname: Yang
authors.affiliation: Institute of Materials Science and Engineering, National Central University, 300 Jhong-Da Road, Taoyuan (Taiwan), Fax: (+886) 3-2805034.
authors.forename: Po-Ling
authors.initials: PL
authors.lastname: Huang
authors.affiliation: Institute of Materials Science and Engineering, National Central University, 300 Jhong-Da Road, Taoyuan (Taiwan), Fax: (+886) 3-2805034.
authors.forename: Xu-Feng
authors.initials: XF
authors.lastname: Luo
authors.affiliation: Institute of Materials Science and Engineering, National Central University, 300 Jhong-Da Road, Taoyuan (Taiwan), Fax: (+886) 3-2805034.
authors.forename: Chueh-Han
authors.initials: CH
authors.lastname: Wang
authors.affiliation: Institute of Materials Science and Engineering, National Central University, 300 Jhong-Da Road, Taoyuan (Taiwan), Fax: (+886) 3-2805034.
authors.forename: Chi
authors.initials: C
authors.lastname: Li
authors.affiliation: Institute of Materials Science and Engineering, National Central University, 300 Jhong-Da Road, Taoyuan (Taiwan), Fax: (+886) 3-2805034.
authors.forename: Yi-Hsuan
authors.initials: YH
authors.lastname: Wu
authors.affiliation: Institute of Materials Science and Engineering, National Central University, 300 Jhong-Da Road, Taoyuan (Taiwan), Fax: (+886) 3-2805034. jkchang@ncu.edu.tw.|Department of Chemical and Materials Engineering, National Central University (Taiwan). jkchang@ncu.edu.tw.|Department of Mechanical Engineering, National Central University (Taiwan). jkchang@ncu.edu.tw.
authors.forename: Jeng-Kuei
authors.initials: JK
authors.lastname: Chang
mesh_terms: D002244:Carbon / Q000737:chemistry; D025802:Electric Capacitance; D004566:Electrodes; D004573:Electrolytes / Q000737:chemistry; D006108:Graphite / Q000737:chemistry*; D052578:Ionic Liquids / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure; D009570:Nitriles / Q000737:chemistry*; D016062:Porosity; D011759:Pyrrolidines / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D004573:Electrolytes; D052578:Ionic Liquids; D009570:Nitriles; D011759:Pyrrolidines; D002244:Carbon; D006108:Graphite; C583114:1-butyl-1-methylpyrrolidinium dicyanamide
keywords: electrochemical properties; graphene; ionic liquid; supercapacitors; surface functional groups