A high-performance hybrid supercapacitor with NiO derived NiO@Ni-MOF composite electrodes

Abstract

Metal-organic framework (MOF) is a class of porous material, which has been gradually applied in supercapacitor fields but remains a significant challenge owing to their intrinsic instability and poor conductivity. Herein, we design a new strategy for synthesizing a well-aligned porous NiO@Ni-MOF/NF cylindrical cage-shape structure derived from NiO self-sacrificed template and precursor. Particularly, this unique construction structure could not only boost the conductivity of the electrode, but also endow the Ni-MOF with a good orientation to promote the transport of electrons and ion in electrochemical energy storage process. The as-prepared NiO@Ni-MOF/NF delivers an amazing specific capacity (1853 C cm−2 at 1 mA cm−2) superior to NiO/NF (242 C cm−2), as well as a relatively low impedance. The hybrid supercapacitor (HSC) is composed of the NiO@Ni-MOF/NF and carbon nanotube (CNT) as the positive and negative electrode, respectively. This HSC exhibits a specific capacitance of 144 F g−1 at 1 A g−1. The maximum energy and power densities of this HSC device reach to 39.2 W h kg−1 and 7000 W kg−1, respectively, showing good cycling stability with 94% capacity retention over 3000 cycles. This work proposes an innovative strategy for rational preparation well-aligned MOF arrays, which could serve as a promising method in the asymmetric supercapacitor devices field.