Facile electrodeposition of 3D concentration-gradient Ni-Co hydroxide nanostructures on nickel foam as high performance electrodes for asymmetric supercapacitors
electrodeposition, concentration-gradient, nickel cobalt hydroxides, supercapacitors
Novel three-dimensional (3D) concentration-gradient Ni–Co hydroxide nano- structures (3DCGNC) have been directly grown on nickel foam by a facile stepwise electrochemical deposition methodand intensively investigated as binder- and conductor-free electrode for supercapacitors. Based on a three- electrode electrochemical characterization technique, the obtained 3DCGNC electrodes demonstrated a high specific capacitance of 1,760 F·g–1 and a remarkable rate capability whereby more than 62.5% capacitance was retained when the current density was raised from 1 to 100 A·g–1. More importantly, asymmetric supercapacitors were assembled by using the obtained 3DCGNC as the cathode and Ketjenblack as a conventional activated carbon anode. The fabricated asymmetric supercapacitors exhibited very promising electrochemical performances with an excellent combination of high energy density of 103.0 Wh·kg–1 at a power density of 3.0 kW·kg–1, and excellent rate capability—energy densities of about 70.4 and 26.0 Wh·kg–1 were achieved when the average power densities were increased to 26.2 and 133.4 kW·kg–1, respectively. Moreover, an extremely stable cycling life with only 2.7% capacitance loss after 20,000 cycles at a current density of 5 A·g–1 was achieved, which compares very well with the traditional double- layer supercapacitors.
Tsinghua University Press
Mingyang Yang,Hua Cheng,Yingying Gu,Zhifang Sun,Jing Hu,Lujie Cao,Fucong Lv,Minchan Li,Wenxi Wang,Zhenyu Wang,Shaofei Wu,Hongtao Liu,Zhouguang Lu, Facile electrodeposition of 3D concentration-gradient Ni-Co hydroxide nanostructures on nickel foam as high performance electrodes for asymmetric supercapacitors. NanoRes.2015, 8(8): 2744–2754