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Millimeter‐Long Vertically Aligned Carbon‐Nanotube‐ Supported Co 3 O 4 Composite Electrode for High‐Performance Asymmetric Supercapacitor
Author(s) -
Yin Yaolong,
Xu Yong,
Zhou Yu,
Yan Ya,
Zhan Ke,
Yang Junhe,
Li Jianqiang,
Zhao Bin
Publication year - 2018
Publication title -
chemelectrochem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.182
H-Index - 59
ISSN - 2196-0216
DOI - 10.1002/celc.201800138
Subject(s) - supercapacitor , materials science , cobalt oxide , current density , capacitance , carbon nanotube , electrode , power density , anode , annealing (glass) , nanotechnology , composite number , oxide , chemical engineering , composite material , chemistry , metallurgy , power (physics) , physics , quantum mechanics , engineering
Cobalt oxide (Co 3 O 4 ) nanoparticles uniformly anchored on vertically aligned carbon nanotube arrays (VACNTs) are synthesized by means of an effective supercritical carbon dioxide (scCO 2 ) assisted impregnation followed by a thermal annealing process. Benefiting from their desirable 3D nanostructure, the Co 3 O 4 /VACNTs (CVN) composites manifest a high specific capacitance of 833 F g −1 at a current density of 1 A g −1 and a good rate capacity with capacitance retention of 89 % even after 20‐fold increase in current density. Coupled with a Fe 3 O 4 /VACNTs (FVN) anode (350 F g −1 at 1 A g −1 ) prepared by the same method, the assembled CVN//FVN asymmetric supercapacitor (ASC) delivers a high energy density of 36 Wh kg −1 (1.65 mWh cm −3 ) at a power density of 0.93 kW kg −1 (0.05 W cm −3 ), and a maximum power density of 13.6 kW kg −1 (0.62 W cm −3 ) at an energy density of 10.6 Wh kg −1 (0.51 mWh cm −3 ). Moreover, even after 5000 charge‐discharge cycles at a current density of 5 A g −1 , the ASC still retains 87 % of its initial specific capacitance. The extraordinary electrochemical performance of the ASC device demonstrates the promise of our VACNTs‐based pseudocapacitive electrode for future energy storage systems.