▎ 摘　　要

A dopamine (DA)-based construction strategy is reported for designing high performance 2D NiCo-hydroxide nanosheets/graphene@polydopamine (NiCo-OH/G@PDA) composites. The strong coordination bond energies between the dopamine and metal ions are crucial for PDA to induce the formation of NiCo-OH nanosheets. The 2D structured NiCo-OH nanosheets can shorten the transportation path of charge and electrons and provide abundant redox reaction sites to enhance the pseudocapacitance. The high redox activity of N/O groups of PDA can also boost the pseudocapacitance to enhance the electrochemical performance. Moreover, the existing graphene in the NiCo-OH/G@PDA composite may construct a conductive network to boost redox reactions. Owing to the synergic effects of 2D NiCo-OH nanosheets, PDA and graphene, the prepared NiCo-OH/G@PDA with an optimized amount of DA delivers a high capacity of 1520 F g(-1) at 1 A g(-1) with an excellent rate capability of 68% at 50 A g(-1) and good cycling stability. Furthermore, the assembled asymmetric supercapacitor exhibits a high energy density of 47 W h kg(-1) at a power density of 1600 W kg(-1). This work can provide a promising novel strategy for the development of 2D metal hydroxides for high-performance supercapacitors.