The development of asymmetric supercapacitors requires the design of electrode construction and the utilization of new electroactive materials. In this regard, an effective strategy is the loading of active materials on an integrated 3D porous graphene-based substrate such as graphene foam (GF). Herein, we successfully designed and fabricated a novel ternary binder-free nanocomposite consisting of polypyrrole, Fe–Co sulfide, and reduced graphene oxide on a nickel foam electrode (PPy/FeCoS-rGO/NF) via a facile, cost-effective, and powerful electrodeposition method for application in high-performance asymmetric supercapacitors. The monolithic 3D porous graphene foam (GF) obtained by the facile immersion method not only improves uniform growth of the FeCoS ultrathin porous nanosheet and conductive PPy film but also significantly boosts the mechanical stability, rate capability, and energy storage capacity. The results revealed that FeCoS interconnected nanosheets coated with a highly conductive PPy layer via the electrodeposition method are well decorated on the wrinkled surface of the graphene foam backbones. The PPy/FeCoS-rGO/NF exhibits excellent electrochemical performance with a high specific capacitance of 3178 F/g at 2 A/g and a good rate capability. The excellent electrochemical performance can be ascribed to the high surface area, superior electronic conductivity, low contact resistance between the PPy/FeCoS-rGO active layer and Ni foam current collector, short diffusion pathway for electrolyte ions, fast electron transfer, and effective utilization of active material during Faradaic charge-storage processes. Benefiting from their superior properties, a hybrid asymmetric supercapacitor is assembled by employing PPy/FeCoS-rGO/NF as the positive electrode and nickel foam coated with reduced graphene oxide (rGO/NF) as the negative electrode. Assembling the PPy/FeCoS-rGO//rGO device exhibits a high specific capacitance of 94 F/g at 1 A/g and an energy density of 28.3 Wh kg–1 at a power density of 810 W kg–1. Moreover, the asymmetric supercapacitor device shows an outstanding cycling performance with 97.5% capacitance retention after 2500 cycles. The obtained results demonstrate the PPy/FeCoS-rGO/NF electrode can be used as a promising electrode material for asymmetric supercapacitor applications.

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