▎ 摘　　要

A high-performing, lightweight, and flexible asymmetric supercapacitor (ASC) using NiCo-layered double hydroxide (NiCo LDH) supported on 3D nitrogen-doped graphene (NG) as a positive electrode and NG as a negative electrode is demonstrated. Highly conductive NG provides fast electron transfer and facilitates (dis)charging of NiCo LDH deposited on it. The composite electrode of NiCo LDH@NG exhibits a high specific capacitance of 1421Fg(-1) at 2Ag(-1). Moreover, the as-obtained hybrid electrode shows an excellent rate capability with a specific capacitance of 1397Fg(-1) at a high current density of 10Ag(-1), which is about 98% of the capacitance obtained at 2Ag(-1). The flexible ASC device shows a specific capacitance of 109Fg(-1) at 0.5Ag(-1) and a maximum energy density of 49Whkg(-1), which is comparable with or superior to previously reported electrodes based on nickel-cobalt hydroxides. Furthermore, an excellent mechanical stability is obtained. Under repeated mechanical bendings, the ASC demonstrates high bending stability up to 450 bending cycles at a 90 degrees angle. Hence, this flexible NiCo LDH@NG electrode that is free of binders and conductive agents shows superior performance and stability, and is a promising candidate for the future wearable energy storage devices.