title: Hierarchically nanoperforated graphene as a high performance electrode material for ultracapacitors.
abstract: High performance is reported for a symmetric ultracapacitor (UC) cell made up of hierarchically perforated graphene nanosheets (HPGN) as an electrode material with excellent values of energy density (68.43 Wh kg⁻¹) and power density (36.31 kW kg⁻¹). Perforations are incorporated in the graphite oxide (GO) and graphene system at room temperature by using silica nanoparticles as template. The symmetric HPGN-based UC cell exhibits excellent specific capacitance (Cs) of 492 F g⁻¹ at 0.1 A g⁻¹ and 200 F g⁻¹ at 20 A g⁻¹ in 1 M H₂SO₄ electrolyte. This performance is further highlighted by galvanostatic charge-discharge study at 2 A g⁻¹ over a large number (1000) of cycles exhibiting 93% retention of the initial Cs. These property features are far superior as compared to those of symmetric UC cells made up of only graphene nanosheets (GNs), i.e. graphene sheets without perforations. The latter exhibit Cs of only 158 F g⁻¹ at 0.1 A g⁻¹ and the cells is not stable at high current density.
authors.affiliation: Centre of Excellence in Solar Energy, National Chemical Laboratory-CSIR-NCL, Dr. Homi Bhabha Road, Pune 411008, India & Network Institute of Solar Energy-CSIR-NISE, New Delhi, India.
authors.forename: Dattakumar
authors.initials: D
authors.lastname: Mhamane
authors.forename: Anil
authors.initials: A
authors.lastname: Suryawanshi
authors.forename: Sreekuttan M
authors.initials: SM
authors.lastname: Unni
authors.forename: Chandrashekhar
authors.initials: C
authors.lastname: Rode
authors.forename: Sreekumar
authors.initials: S
authors.lastname: Kurungot
authors.forename: Satishchandra
authors.initials: S
authors.lastname: Ogale
mesh_terms: D025802:Electric Capacitance; D004566:Electrodes; D006108:Graphite / Q000737:chemistry*; D049329:Nanostructures / Q000737:chemistry*; D036103:Nanotechnology / Q000379:methods*
chemical_list: D006108:Graphite
keywords: charge-discharge; graphene; perforated materials; silica; ultracapacitors