High-performance freestanding supercapacitor electrode based on polypyrrole coated nickel cobalt sulfide nanostructures

Abstract

In the present work, we report the successful fabrication of dandelion-like Nickel–Cobalt Sulfide@Polypyrrole microspheres through the hydrothermal method and its possible application as a binder-free electrode in supercapacitors. This electrode exhibited low charge transfer resistance with a remarkable specific capacitance of 2554.9 F g−1 at 2.54 A g−1, in addition to considerable cycle life stability. Also, an asymmetric device was prepared using NiCo2S4@PPy/NF as positive and rGO/NF as negative electrodes. This asymmetric supercapacitor exhibited a specific capacitance of 98.9 F g−1 at 1.84 A g−1 and delivered an energy density of 35.17 Wh kg−1 at a power density of 1472 W kg−1. Such a remarkable performance can be originated from the synergy effect of NiCo2S4 and PPy and the direct deposition of the composite on the current collector. Our findings suggest the dandelion-like NiCo2S4@PPy as a promising material for making high-performance supercapacitors.