Synthesis of Morphology Controlled NiCo-LDH Microflowers Derived from ZIF-67 using Binary Additives and Their Excellent Asymmetric Supercapacitor Properties

•NiCo-LDH with a three-dimensional (3D) hierarchical hexagonal flower-like structure is synthesized.•Binary additives H2tfbdc and HMT are used to tune morphology and deliver large interlayer spacing of 9.3 d(Å).•The synergic effect of hydrothermal heating temperature and time is optimized.•The assembled ASC supercapacitor device exhibits excellent energy density and power density.