Novel three-dimensional （3D） concentration-gradient Ni-Co hydroxide nanostructures （3DCGNC） have been directly grown on nickel foam by a facile stepwise electrochemical deposition method and intensively investigat...Novel three-dimensional （3D） concentration-gradient Ni-Co hydroxide nanostructures （3DCGNC） have been directly grown on nickel foam by a facile stepwise electrochemical deposition method and 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 doublelayer supercapacitors.展开更多
基金This work was supported by the National Natural Science Foundation of China （No. 21001117）, the Shenzhen Peacock Plan （No. KQCX20140522150815065）, and the Starting-Up Funds of South University of Science and Technology of China （SUSTC） through the Talent Plan of the Shenzhen Government. H. T. L. acknowledges the support from a Key Project of the Hunan Provincial Science and Technology Plan （No. 2014FJ2007）.
文摘Novel three-dimensional （3D） concentration-gradient Ni-Co hydroxide nanostructures （3DCGNC） have been directly grown on nickel foam by a facile stepwise electrochemical deposition method and 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 doublelayer supercapacitors.
