title: Interconnected carbon nanosheets derived from hemp for ultrafast supercapacitors with high energy.
abstract: We created unique interconnected partially graphitic carbon nanosheets (10-30 nm in thickness) with high specific surface area (up to 2287 m(2) g(-1)), significant volume fraction of mesoporosity (up to 58%), and good electrical conductivity (211-226 S m(-1)) from hemp bast fiber. The nanosheets are ideally suited for low (down to 0 °C) through high (100 °C) temperature ionic-liquid-based supercapacitor applications: At 0 °C and a current density of 10 A g(-1), the electrode maintains a remarkable capacitance of 106 F g(-1). At 20, 60, and 100 °C and an extreme current density of 100 A g(-1), there is excellent capacitance retention (72-92%) with the specific capacitances being 113, 144, and 142 F g(-1), respectively. These characteristics favorably place the materials on a Ragone chart providing among the best power-energy characteristics (on an active mass normalized basis) ever reported for an electrochemical capacitor: At a very high power density of 20 kW kg(-1) and 20, 60, and 100 °C, the energy densities are 19, 34, and 40 Wh kg(-1), respectively. Moreover the assembled supercapacitor device yields a maximum energy density of 12 Wh kg(-1), which is higher than that of commercially available supercapacitors. By taking advantage of the complex multilayered structure of a hemp bast fiber precursor, such exquisite carbons were able to be achieved by simple hydrothermal carbonization combined with activation. This novel precursor-synthesis route presents a great potential for facile large-scale production of high-performance carbons for a variety of diverse applications including energy storage.
authors: Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta T6G 2 V4, Canada.
authors: Huanlei
authors: H
authors: Wang
authors: Zhanwei
authors: Z
authors: Xu
authors: Alireza
authors: A
authors: Kohandehghan
authors: Zhi
authors: Z
authors: Li
authors: Kai
authors: K
authors: Cui
authors: Xuehai
authors: X
authors: Tan
authors: Tyler James
authors: TJ
authors: Stephenson
authors: Cecil K
authors: CK
authors: King'ondu
authors: Chris M B
authors: CM
authors: Holt
authors: Brian C
authors: BC
authors: Olsen
authors: Jin Kwon
authors: JK
authors: Tak
authors: Don
authors: D
authors: Harfield
authors: Anthony O
authors: AO
authors: Anyia
authors: David
authors: D
authors: Mitlin
mesh_terms: D000327:Adsorption; D002188:Cannabis / Q000737:chemistry*; D025802:Electric Capacitance; D004563:Electrochemistry; D006108:Graphite / Q000737:chemistry*; D049329:Nanostructures / Q000737:chemistry*; D009584:Nitrogen / Q000737:chemistry; D013499:Surface Properties; D013997:Time Factors
chemical_list: D006108:Graphite; D009584:Nitrogen