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Issue 24, 2017
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Multi-porous Co3O4 nanoflakes @ sponge-like few-layer partially reduced graphene oxide hybrids: towards highly stable asymmetric supercapacitors

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Abstract

The controlled growth of metal oxide nanostructures within hierarchically porous conductive carbon-based frameworks is critically important to achieving high volumetric performance and appropriate channel size for energy storage applications. Herein, we grow cobalt oxide (Co3O4) nanoflakes, using a sequential-electrodeposition process, into spherically porous sponge-like few-layer partially reduced graphene oxide (SrGO) synthesized by template-directed ordered assembly. Maximum specific/volumetric capacitances of 1112 F gCo3O4−1 (at 3.3 A gCo3O4−1), 178 F cm−3 (at 2.6 A cm−2), and 406 F gtotal−1 (at 1 A gtotal−1) and sensible rate capability (80% retention by increasing the charge/discharge current from 1 A g−1 to 16 A g−1) are obtained for the Co3O4 nanoflakes@SrGO hybrid electrodes. Besides, an asymmetric supercapacitor is made with the Co3O4[63%]@SrGO[37%] hybrid and activated carbon as a positive and a negative electrode, respectively. Electrochemical results indicate an energy density of 23.3 W h kg−1 at a high power density of 2300 W kg−1 (discharge time of about 42 s) and 62% retention even at a remarkable power density of 36 600 W kg−1 (discharge time of 1.6 s). Moreover, it shows excellent cycling stability with no decay after 20 000 charge/discharge cycles. This performance is attributed to the unique pore-sizes for an ion to channel into the porous structures, conductivity, and mechanical stability of the SrGO framework, which makes it promising for next-generation supercapacitors.

Graphical abstract: Multi-porous Co3O4 nanoflakes @ sponge-like few-layer partially reduced graphene oxide hybrids: towards highly stable asymmetric supercapacitors

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Article information


Submitted
20 Jan 2017
Accepted
27 Apr 2017
First published
27 Apr 2017

J. Mater. Chem. A, 2017,5, 12569-12577
Article type
Paper

Multi-porous Co3O4 nanoflakes @ sponge-like few-layer partially reduced graphene oxide hybrids: towards highly stable asymmetric supercapacitors

M. Qorbani, T. Chou, Y. Lee, S. Samireddi, N. Naseri, A. Ganguly, A. Esfandiar, C. Wang, L. Chen, K. Chen and A. Z. Moshfegh, J. Mater. Chem. A, 2017, 5, 12569
DOI: 10.1039/C7TA00694B

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