Structural properties and supercapacitive performance evaluation of the nickel oxide/graphene/polypyrrole hybrid ternary nanocomposite in aqueous and organic electrolytes

Recently, hybrid supercapacitors have attracted tremendous attention as promising energy storage and conversion devices due to their excellent energy density and high power density. In the present work, a novel pioneering hybrid ternary nanocomposite of NiO/Gr/PPy was synthesized by a low-cost co-precipitation method, followed by heat treatment and in-situ chemical polymerization. The as-synthesized nanocomposite was drop-cast on a modified Cu current collector to enhance the supercapacitive performance and stability in the electrolyte. The results of electrochemical characterization in 6 M KOH revealed the high specific capacitance and energy density of 970.85 F g⁻¹ and 33.71 Wh kg⁻¹ at 1 A g⁻¹, respectively. This can be attributed to the synergic effect and hybrid performance of NiO, Gr, and PPy. Moreover, a full symmetric cell was assembled by using this hybrid ternary nanocomposite and evaluated in TEA-BF₄/AN. The results showed the high specific capacitance and energy density of 66.17 F g⁻¹ and 36.76 Wh kg⁻¹ within the 2 V potential window, respectively.