Construction of high-performance asymmetric supercapacitor based on the hierarchical Ni3S2/CoFe LDH/Ni foam hybrid

Abstract

Transition metal layered double hydroxides (TM LDHs) nanosheets have stimulated tremendous research enthusiasm, which is gifted with their tunable chemical compositions, large layer distances and superior electrochemical performance. However, the small number of electroactive sites and the low electrical conductivity have restricted their applications in electrode materials. Herein, we construct a hierarchical Ni3S2/CoFe LDH/Ni foam (Ni3S2/CoFe LDH/NF) hybrid by a facile hydrothermal synthesis followed by an electrodeposition without using any chemical binder. The as-constructed Ni3S2/CoFe LDH/NF exhibits an ultrahigh areal capacitance of 5.08 F cm−2 and an excellent rate capability with a capacitance retention of 73.8% at the high current density of 20 mA cm−2. Furthermore, the constructed asymmetric supercapacitor (ASC) based on the Ni3S2/CoFe LDH/NF anode and the activated carbon (AC) cathode shows both a high power density of 986 W kg−1 and a high energy density of 47.31 Wh kg−1 with high cycling stability of 93.4% initial capacitance after 5000 cycles, demonstrating an enormous potential for the practical application in energy storage devices.