Hollow nanostructure boosts the surface capacitive charge storage of NiCo-LDH derived from metal-organic framework for high performance asymmetric supercapacitor

Abstract

Layered double hydroxide (LDH) has great potential as advanced electrode material for supercapacitor. In this paper, by tuning the reaction temperature, two Ni Co-LDH nanostructures (hollow nanocage and sea urchin) were synthesized through the hydrolysis etching process of ZIF-67 crystals and Ni2+ ions. It has been found that the morphology of the electrode material has a great influence on the electrochemical performance and analysis the reason of this behavior is essential for understanding the morphology-related electrochemical performance. Here, a much more capacitive charge storage behavior of hollow Ni Co-LDH than that of sea urchin-shaped product is demonstrated by electrochemical kinetic analysis. The higher capacitive behavior of hollow Ni Co-LDH suggests a rapid surface redox reaction during the electrochemical process, which will lead to excellent electrochemical properties. An asymmetric supercapacitor assembled using hollow NiCo-LDH as the positive electrode displays a high energy density of 88.6 Wh kg−1 at 749.9 W kg−1, further demonstrating its great application potential. These results provide insights into the reasons for the excellent electrochemical performance of hollow nanostructure.