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Volume 91 Issue 7 | p. 43 | Concentrates
Issue Date: February 18, 2013

Crumpled Graphene Retains High Capacitance

Resistance to aggregation and sheet stacking bodes well for device scale-up
Department: Science & Technology
Keywords: graphene, Jiaxing Huang, capacitor, ultracapacitor, crumpled graphene
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Capacitors made from thin graphene flakes function poorly because the flakes tend to aggregate and restack during processing, thereby reducing graphene area and device capacitance. Crumpled graphene sheets avoid that problem.
Credit: ACS Nano
Graphic symbolically shows crumpled and thin sheets of grapheme. Capacitors made from thin graphene flakes function poorly because the flakes tend to aggregate and restack during processing, thereby reducing graphene area and device capacitance, as show in plot. Crumpled graphene sheets avoid that problem.
 
Capacitors made from thin graphene flakes function poorly because the flakes tend to aggregate and restack during processing, thereby reducing graphene area and device capacitance. Crumpled graphene sheets avoid that problem.
Credit: ACS Nano

Graphene’s intrinsically high conductivity and extreme thinness should make it outstanding for use in advanced electronics such as ultracapacitors, a type of charge storage device. In practice, those properties are often difficult to exploit when standard procedures are used to prepare bulk quantities of graphene from graphite powders. Those methods tend to cause ultrathin graphene flakes to aggregate and form stacks, greatly reducing the material’s surface area and electronic and ionic conductivity. A recently developed aerosol-based method to make crumpled graphene sheets can overcome those problems, because like wadded paper balls, crumpled graphene sheets resist aggregation and compression. Jiayan Luo, Hee Dong Jang, and Jiaxing Huang of Northwestern University prepared a series of capacitors with increasing mass of crumpled graphene. The capacitance values increased roughly linearly with mass, suggesting that the devices could be scaled up to meet the needs of various applications (ACS Nano, DOI: 10.1021/nn3052378). In contrast, increasing the loading of flat graphene leads to successively weaker capacitance per weight of graphene, as the increase in material causes greater aggregation, the team reports.

 
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ISSN 0009-2347
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