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Issue 35, 2017
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2D reentrant auxetic structures of graphene/CNT networks for omnidirectionally stretchable supercapacitors

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Abstract

Stretchable energy storage systems are essential for the realization of implantable and epidermal electronics. However, high-performance stretchable supercapacitors have received less attention because currently available processing techniques and material structures are too limited to overcome the trade-off relationship among electrical conductivity, ion-accessible surface area, and stretchability of electrodes. Herein, we introduce novel 2D reentrant cellular structures of porous graphene/CNT networks for omnidirectionally stretchable supercapacitor electrodes. Reentrant structures, with inwardly protruded frameworks in porous networks, were fabricated by the radial compression of vertically aligned honeycomb-like rGO/CNT networks, which were prepared by a directional crystallization method. Unlike typical porous graphene structures, the reentrant structure provided structure-assisted stretchability, such as accordion and origami structures, to otherwise unstretchable materials. The 2D reentrant structures of graphene/CNT networks maintained excellent electrical conductivities under biaxial stretching conditions and showed a slightly negative or near-zero Poisson's ratio over a wide strain range because of their structural uniqueness. For practical applications, we fabricated all-solid-state supercapacitors based on 2D auxetic structures. A radial compression process up to 1/10th densified the electrode, significantly increasing the areal and volumetric capacitances of the electrodes. Additionally, vertically aligned graphene/CNT networks provided a plentiful surface area and induced sufficient ion transport pathways for the electrodes. Therefore, they exhibited high gravimetric and areal capacitance values of 152.4 F g−1 and 2.9 F cm−2, respectively, and had an excellent retention ratio of 88% under a biaxial strain of 100%. Auxetic cellular and vertically aligned structures provide a new strategy for the preparation of robust platforms for stretchable energy storage electrodes.

Graphical abstract: 2D reentrant auxetic structures of graphene/CNT networks for omnidirectionally stretchable supercapacitors

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Publication details

The article was received on 22 Apr 2017, accepted on 14 Aug 2017 and first published on 15 Aug 2017


Article type: Paper
DOI: 10.1039/C7NR02869E
Citation: Nanoscale, 2017,9, 13272-13280

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    2D reentrant auxetic structures of graphene/CNT networks for omnidirectionally stretchable supercapacitors

    B. S. Kim, K. Lee, S. Kang, S. Lee, J. B. Pyo, I. S. Choi, K. Char, J. H. Park, S. Lee, J. Lee and J. G. Son, Nanoscale, 2017, 9, 13272
    DOI: 10.1039/C7NR02869E

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