Hierarchical polypyrrole/Ni3S2@MoS2 core–shell nanostructures on a nickel foam for high-performance supercapacitors

Abstract

Hierarchical polypyrrole/Ni₃S₂@MoS₂ core–shell nanostructures have been successfully designed and constructed on a Ni foam substrate with the aid of a two-step solution-phase synthesis protocol, where the polypyrrole is sandwiched between the metal sulfide and nickel foam substrate. The as-prepared hierarchical polypyrrole/Ni₃S₂@MoS₂ active materials exhibit superior supercapacitor performance with an areal capacitance of 5.29 F cm⁻² at a current density of 2.5 mA cm⁻² and 4 F cm⁻² even at a high power density of 10 mA cm⁻², and 6 times the capacitance compared to the Ni₃S₂@MoS₂ core–shell nanowires. An asymmetric supercapacitor device based on polypyrrole/Ni₃S₂@MoS₂ as the positive electrode, porous carbon as the negative electrode and KOH as the electrolyte can work steadily at a voltage of 1.5 V, and present excellent electrochemical performance. The stupendous specific capacitance, enhanced cycle stability, elevated energy density and power density as an asymmetric supercapacitor device of these electrode materials indicate that it could be a potential candidate in the field of supercapacitors.