Jul 08, 2013 |
Mesoporous graphene nano-balls as enhanced supercapacitor material
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(Nanowerk News) Korean Researchers from Ulsan National Institute of Science and Technology (UNIST) developed a new method to massively synthesize enhanced yet affordable materials for supercapacitors.
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Supercapacitors have attracted increasing attention due to their long life cycle, highly reversible charge storage process and specific power density along with increased concern over the exhaustion of natural resources.
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Graphene has been recognized as a promising active material for supercapacitors due to its outstanding electrical conductivity and large surface area, as they are the two most important requirements for supercapacitors.
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Among the various methods for the fabrication of graphene sheets, the chemical vapor deposition (CVD) technique is highly recommended due to the high conductivity of as-prepared graphene. But the scalability is still needed for commercialization. Additionally these limitations called for great interest on further improvement.
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The research team led by Prof. Ji-Hyun Jang from UNIST, previously reported a novel approach to synthesize CVD-grown three-dimensional graphene nano-networks (3-D GNs) that can be mass produced while retaining the excellent properties of 2D graphene and published in Scientific Reports in May 2013.
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Here, Prof. Jang extended her previous research in Scientific Reports and demonstrated a unique route to obtain a mass-producible mesoporous graphene nano-ball (MGB) with a large surface area and great conductivity, via precursor-assisted CVD, using metal precursors as a catalyst which is applicable to supercapacitors ("Chemical Vapor Deposition of Mesoporous Graphene Nanoballs for Supercapacitor").
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A mass-producible mesoporous graphene nanoball (MGB) was fabricated via a precursor-assisted chemical vapor deposition (CVD) technique for supercapacitor application.
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Prof. Ji-Hyun Jang is from the Interdisciplinary School of Green Energy at UNIST and the fellow researchers include Jung-Soo Lee, Sun-I Kim and Jong-Chul Yoon from the Interdisciplinary School of Green Energy at UNIST.
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Compared to the conventional graphene synthesis methods, a new way, suggested by the UNIST research group, is scalable and able to produce high quality and customizable graphene with better environmental impacts.
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With the resulting materials, mesoporous graphene balls, the capacity of supercapacitor has been improved significantly. Due to the unique mesoporous structure, three-dimensional networks are formed, which help to improve conductivity. Furthermore, mesopores inside the graphene surfaces induce nanochannels to transport ions in electrolyte, and improve the properties of supercapacitor.
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The MGB presents a specific surface area of 508 m2/g and mesoporosity with a mean pore diameter of 4.27 nm. The conductivity of the p-doped MGB obtained from more than 10 samples was 6.5 S/cm. The MGB-based supercapacitor shows good performance, including an excellent capacitance of 206 F/g and 96% retention of capacitance after 10,000 cycles even at a high current density.
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"Our work is very meaningful since we succeed in the fabrication of CVD-grown graphene with high qualities on a gram scale," said Prof. Jang. "When the mesoporous graphene balls are used as an electrode material for supercapacitor, it proves great potential for energy storage devices with high efficiency."
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She also said "If the properties of mesoporous graphene are improved further by continuous research, developing an electric vehicle with high power will become a realization not just a dream," showing their future research plan.
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