Nickel foam supported hierarchical NiCo2S4@NiFe LDH heterostructures as highly efficient electrode for long cycling stability supercapacitor

Abstract

Layered double hydroxides (LDHs) based heterostructures provide an opportunity for the development of high-performance supercapacitors. Up till now, hierarchical NiCo2S4@NiFe LDH heterostructure is scarcely investigated for supercapacitor. In this work, the hierarchical NiCo2S4@NiFe LDH heterostructure nanosheet arrays on Ni-foam (NF) were synthesized by a facile hydrothermal method. As the supercapacitor electrode, it has been revealed that the incorporation of NiFe can significantly increase the capacitive performance of the heterostructure. At a current density of 1 Ag−1, a specific capacitance of NiCo2S4@NiFe LDH electrode was reached up to 827 Fg−1, outperforming that of pristine NiCo2S4 and NiFe LDH. Moreover, the electrode keeps 90.2% of its preliminary capacitance after 12,000 cycles at 5 A g−1. In addition, NiCo2S4@NiFe LDH electrode offer high energy density of 38.1 W h kg−1 and power density of 1800 W kg−1. According to DFT calculations, NiFe-LDH adsorption on NiCo2S4 is strong and governed by large interfacial interactions with a charge transfer of 0.44 eV to NiCo2S4 surface thus demonstrating the significantly improved electrochemical performance. Hence, such an outstanding electrochemical finding suggest that NiCo2S4@NiFe LDH heterostructures could be attractive electrode materials as practical supercapacitors for next generation energy storage devices.