Construction of core-shell Ni@Ni3S2@NiCo2O4 nanoflakes as advanced electrodes for high-performance hybrid supercapacitors

Abstract

A universal strategy was used to synthesize the core-shell structure Ni@Ni3S2@NiCo2O4 nanoflakes. As wished, benefiting from the core-shell structure of nanoflakes, the as-synthesized Ni@Ni3S2@NiCo2O4 electrode materials show excellent electrochemical performance. Furthermore, the effect of ethylenediamine on the electrochemical performances of the Ni@Ni3S2@NiCo2O4 nanoflakes was studied. In a three-electrode system, the specific capacitance achieves 13.4 F cm−2 at a current density of 1 mA cm−2 and even 11.7 F cm−2 at 10 mA cm−2. Moreover, the fabricated hybrid supercapacitor was assembled using Ni@Ni3S2@NiCo2O4 as a positive electrode, the activated carbon (AC) as a negative electrode, and KOH as an electrolyte, respectively. The assembled device delivers an energy density of 57 Wh∙kg−1 at a power density of 3700 W kg−1 and good cycling stability (82% capacitance retention after 8000 cycles), demonstrating its excellent energy storage property in supercapacitor.