The key role of microscopic structure and graphene sheet-high homogenization in the high rate capability and cycling stability of Ni-Co LDH.

As a typical electrode material in Faraday supercapacitors (FSs), Ni(OH)2 has some intrinsic issues such as low electrical conductivity and structural instability, resulting in its low performance. In view of these issues, we design a multifunctional nanostructure, rigid nanosheet-interlaced structure of Ni-Co LDH/graphene to improve the electrical conductivity and structural stability of Ni(OH)2. Under the high shear applied by a high shear mixer (HSM) and the regulation of polyvinylpyrrolidone (PVP), the designed structure is realized. Benefitting from the well-designed structure and improved electrical conductivity of the graphene sheet-high homogenization, Ni-Co LDH/graphene presents the expected performance. It exhibits a high specific capacity of 1020 C g-1 at a low current density of 2.7 A g-1 and excellent high rate performance (637.5 C g-1 at 62.5 A g-1). The asymmetrical supercapacitors (ASCs) assembled with the composite as the positive material show high energy density (86.5 W h kg-1 at a power density of 695.7 W kg-1). Due to the improved structural stability, the ASCs also exhibit high cycling stability (a capacity retention of 97.8% after 10 000 charge-discharge cycles).