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Facile dip coating processed 3D MnO2-graphene nanosheets/MWNT-Ni foam composites for electrochemical supercapacitors

Authors :
Yinyi Gao
Tian Ouyang
Guiling Wang
Kui Cheng
Ke Ye
Dianxue Cao
Shuying Kong
Source :
Electrochimica Acta. 226:29-39
Publication Year :
2017
Publisher :
Elsevier BV, 2017.

Abstract

Carbon materials, especially graphene nanosheets (GNS) and/or multi-walled carbon nanotube (MWNT), have been widely used as electrode materials for supercapacitor due to their advantages of higher specific surface area and electronic conductivity, but the relatively low specific capacitance thus results in low energy density hindering their large applications. On the contrary, MnO2 exhibits higher energy density but poor electrical conductivity. In order to obtain high performance supercapacitor electrode, here, combining the advantages of these materials, we have designed a facile two-step strategy to prepare 3D MnO2-GNS-MWNT-Ni foam (MnO2-GM-Ni) electrode. First, GNS and MWNT is wrapped on the surface of Ni foam (GM-Ni) via a “dip & dry” method by using an organic dye as a co-dispersant. Then, by using this 3D GM-Ni as substrate, MnO2 nanoflakes are in-situ supporting on the surface of GNS and MWNT through a hydrothermal reaction. The specific capacitances of MnO2-GM-Ni electrode reach as high as 470.5 F g−1 at 1 A g−1. Furthermore, we have successfully fabricated an asymmetric supercapacitor with MnO2-GM-Ni and GM-Ni as the positive and negative electrodes, respectively. The MnO2-GM-Ni//GM-Ni asymmetric supercapacitor exhibits a maximum energy density of 35.3 Wh kg−1 at a power density of 426 W kg−1 and also a favorable cycling performance that 83.8% capacitance retention after 5000 cycles. These results show manageable and high-performance which offer promising future for practical applications.

Details

ISSN :
00134686
Volume :
226
Database :
OpenAIRE
Journal :
Electrochimica Acta
Accession number :
edsair.doi...........7f25939fd4927040323ed116683aab3c
Full Text :
https://doi.org/10.1016/j.electacta.2016.12.158