Facile synthesis of core-shell nanostructured hollow carbon nanospheres@nickel cobalt double hydroxides as high-performance electrode materials for supercapacitors

Core-shell nanostructured hollow carbon nanospheres@ nickel cobalt double hydroxides ( HCNs@ NiCo-LDH) were fabricated using a facile hydrothermal method and investigated as high-performance electrode materials for supercapacitors. HCNs were acquired by a successive polymerization, carbonization and etching process, which was subsequently wrapped by ultrathin NiCo-LDH nanosheets. The HCNs@ NiCo-LDH electrode achieved a high specific capacitance ( 2558 F g(-1) at 1 A g-1) and outstanding rate capability with 74.9% capacitance retention after a 20-fold increase in current density. Capacitances of 2405, 2310, 2168, 2006 and 1916 F g(-1) can be achieved at rates of 3, 5, 10, 15 and 20 A g(-1), respectively, which are much higher than the specific capacitances of most reported carbon loaded NiCo-LDH. Specifically, the assembled HCNs@ NiCo-LDH// graphene asymmetric supercapacitor displayed distinguished capacitive behaviors with a prominent specific capacitance of 172.8 F g(-1) and eminent cycling stability with 93.5% capacitance retention after 3000 cycles. These remarkable electrochemical properties indicate that the unique HCNs@ NiCo-LDH core-shell electrode is highly promising for application in energy storage fields.