Applied Surface Science | 2019
Construction of hierarchical Co-Ni-S nanosheets as free-standing electrode for superior-performance asymmetric supercapacitors
Abstract
Abstract Co-Ni-S nanoarchitectures with considerable conductivity and superior electrochemical performance have been successfully designed and grown on Ni foam substrates. The collective effects of structure and composition endow Co-Ni-S electrodes better electrochemical performance with ultra-high areal capacitances of 6.3\u202fF\u202fcm−2 at 1\u202fmA\u202fcm−2 (4.2\u202fF\u202fcm−2 retained at 8\u202fmA\u202fcm−2) and remarkable rate capability of 65% at 10\u202fmA\u202fcm−2. Correspondingly, asymmetric supercapacitors are assembled with Co-Ni-S sample and active carbon as the positive and negative electrodes, which display an excellent energy density of ∼50\u202fWh\u202fkg−1 at a power density of ∼0.783\u202fkW\u202fkg−1. Furthermore, the capacitance maintains 71% of the initial value after cycling 6000 times at 1\u202fA\u202fg−1. These results have great significance for the optimization of asymmetric supercapacitors as the energy-storage devices for the next generation.