Porous nickel-cobalt layered double hydroxide nanoflake array derived from ZIF-L-Co nanoflake array for battery-type electrodes with enhanced energy storage performance

In view of the complicated synthesis procedures of metallic layered double hydroxides (LDHs) in general preparation, we here report a facile route for synthesizing porous nickel-cobalt layered double hydroxide nanoflake array (Ni-Co LDH-NFA) on nickel foam on the base of our previously reported leaf-like Co containing zeolitic imidazolate framworks (ZIF-L-Co). The ZIF-L-Co nanoflake array (ZIF-NFA) is first grown on nickel foam, which serves as a sacrificial template to synthesize Ni-Co LDH-NFA when it reacts with nickel nitrate at room temperature. The as-prepared Ni-Co LDH-NFA could be directly used as battery-type electrodes without polymer binder. Due to the highly ordered layered crystal structure of LDH and the well-defined porous nanostructure of nanoflake array, such Ni-Co LDH-NFA electrode exhibits outstanding specific capacity of 894 C g(-1) at a current density of 2 A g(-1). In addition, an assembled asymmetric supercapacitor device also exhibits excellent specific energy density of 48.6 Wh kg(-1) at a specific power density of 1700 W kg(-1). Even at a high power density of 17 kW kg(-1), the device could still remain an energy density of 18.5 Wh kg(-1). (C) 2017 Elsevier Ltd. All rights reserved.