Three-dimensional hierarchical interwoven nitrogen-doped carbon nanotubes/CoxNi1-x-layered double hydroxides ultrathin nanosheets for high-performance supercapacitors

• Published in: Electrochimica acta 2016-06, Vol.203, p.21-29
• Main Authors: Wu, Jian, Liu, Wei-Wei, Wu, Yu-Xuan, Wei, Ting-Cha, Geng, Dongsheng, Mei, Jun, Liu, Hao, Lau, Woon-Ming, Liu, Li-Min
• Format: Article
• Language: English
• Subjects: Carbon nanotubes; First-principles calculations; Layered double hydroxides; Nitrogen doping; Supercapacitor
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/j.electacta.2016.04.033

•A facile, low-cost and scalable route has been developed to design and fabricate 3D hierarchical Ni foam/N-CNTs/CoxNi1-x-LDHs NSs electrodes.•The Ni foam/N-CNTs/Co0.5Ni0.5-LDHs NSs electrode possesses the maximum specific capacitance of 2170Fg−1 (1Ag−1) and areal capacitance of 1.62Fcm−2 (1mAcm−2).•First-principles calculations further reveal that the Co doping can effectively reduce the band gap of Ni(OH)2 and increase the conductivity. Three-dimensional (3D) interwoven nitrogen-doped carbon nanotubes (N-CNTs)/CoxNi1-x-layered double hydroxides (CoxNi1-x-LDHs) ultrathin nanosheets on Ni foam have been rationally designed via the combination of chemical vapor deposition and electrochemical deposition approaches. The CoxNi1-x-LDHs nanosheets are uniformly distributed on the N-CNTs, which can not only serve as the stable frame to improve the specific surface area, but also can enhance the conductivity. The Ni foam/N-CNTs/Co0.5Ni0.5-LDHs nanosheets electrode displays a remarkable maximum capacitance (2170Fg−1 at 1Ag−1 and 1.62Fcm−2 at 1mAcm−2), excellent rate capability (80.9% specific capacitance retention at 20Ag−1 and 75.8% areal capacitance retention at 30mAcm−2) and good cycling stability. First-principles calculations further reveal that the Co doping can effectively reduce the band gap of Ni(OH)2 and increase the conductivity. This work demonstrates a facile synthesis strategy of 3D hierarchical Ni foam/N-CNTs/CoxNi1-x-LDHs nanosheets electrode with remarkable electrochemical properties, which can be used in energy storage and conversion.