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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Flexible and lightweight fiber-shaped micro-supercapacitors have attracted tremendous attentions in the next-generation portable electronic devices, due to their high flexibility, tiny volume, and wearability. Herein, we successfully fabricated a ternary...

Miniaturization of electronic devices with portable, flexible and wearable characteristics created a great demand for high-performance microscale energy storage devices with lightweight and flexible properties. Among the energy storage devices, wire-shaped supercapacitors (WSSCs) have recently received tremendous attention due to their tiny volume, wearability, high flexibility and potential applications in the next-generation portable/wearable electronic devices. Herein, we successfully fabricated a porous dendritic Ni–Cu film on Cu wire substrate (CWE) for fabrication of high-performance wire-type supercapacitors. The porous structure with dendritic morphology provides a high surface area, short ion diffusion pathway and low contact resistance between electroactive materials and metal wire electrode. The Ni­(OH)2 electroactive material is then deposited on Ni–Cu/CWE. The fabricated Ni­(OH)2/Ni–Cu/CWE exhibits excellent electrochemical performances with high areal (volumetric and length) specific capacitance of 12.2 F cm–2 (1220.89 F cm–3, 1.53 F cm–1), respectively at a current density of 4 mA cm–2, and an excellent cycle stability (100% even after 3500 cycles). A novel fiber-shaped flexible asymmetric micro–supercapacitor (ASC) based on Ni­(OH)2/Ni–Cu/CW as positive electrode and reduced graphene oxide/carbon fiber (RGO/CF) as the binder free negative electrode was assembled. This device can be operated reversibly in the voltage range of 0–1.6 V and exhibited a maximum areal and volumetric energy (E A = 195 μWh cm–2, E V = 15.04 mWh cm–3) and power (P A = 7643 μW cm–2, P V = 588 mW cm–3) densities. In addition, the ASC device also exhibits an excellent cycling stability with 95.7% capacitance retention after 5000 cycles and good mechanical stability, which is checked by bending of the whole device at various angles. These promising results indicated the great potential of our fabricated device for portable, flexible and wearable applications.