Rational Design of Sandwiched Ni–Co Layered Double Hydroxides Hollow Nanocages/Graphene Derived from Metal–Organic Framework for Sustainable Energy Storage

摘要

In situ growth of Ni–Co layered double hydroxides on graphene nanosheets by virtue of metal–organic framework as a sacrifice template is reported, which yields hollow nanocages uniformly deposited on graphene nanosheets. The strong impact of graphene amount on the electrochemical performance of Ni–Co layered double hydroxides is illustrated. Controlling the mass of graphene (15 mg) leads to a maximum specific capacitance of 1265 F g–1, high rate capability (50% capacitance retention after increasing current density ten times), and good cycling life (92.9% capacitance retention after 2000 circles). The combination of battery-type Ni–Co LDH hollow nanocages/graphene composite and active carbon allows for the excellent electrochemical performance measured in an asymmetric device. In detail, the assembled asymmetric supercapacitor is able to deliver maximum specific capacitance 170.9 F g–1 in a potential window of 0–1.7 V, high energy density (68.0 Wh kg–1), as well as excellent power output (4759 W kg–1). These electrochemical performances, in combination with its facile fabrication, render hollow Ni–Co LDH/graphene composite as a promising electrode material in a sustainable energy storage device.]]>