The controlled fabrication of hierarchical CoS2@NiS2 core-shell nanocubes by utilizing prussian blue analogue for enhanced capacitive energy storage performance

Abstract

In this project, for the first time we successfully develop an approach to fabricate a novel core-shell structure of CoPBA@Ni(OH)2, in which Ni(OH)2 nano-sheets covered on the surface of CoPBA nanocubes through in-situ etching and growing processes, furthermore, being sulfurized into its hierarchical porous structure of CoS2@NiS2. The CoS2@NiS2 composite as a high-performance surpercapacitor electrode has been demonstrated. It exhibits very high specific capacitance value of 1731.2 F g−1 at 1 A g−1, excellent rate performance of 83.5% retention at 10 A g−1 and cycle performance with 87.1% retention after 5000 cycles together with distinguished coulombic efficiency of around 100%. Kinetic analysis and electrochemical impedance spectroscopy (EIS) results reveal the related mechanism. Herein, prussian blue analogue (PBA) as central core with cubic skeleton displays some great advantages, (1) it can provide more efficient electron conduction path to reduce the resistance of composite, (2) it can effectively prevent the agglomeration of electroactive Ni(OH)2 as well as sulfurized CoS2@NiS2 composite, (3) it can reduce ion diffusion pathway with mesoporous structure and enlarged surface area, greatly improving cycle stability. Such synthetic strategy opens up a new avenue for the effective construction of core-shell structure based on PBA basement for promising supercapacitor application.