Hierarchical NiCo LDH–rGO/Ni Foam Composite as Electrode Material for High-Performance Supercapacitors

In this study, a bulk composite material symbolized as NiCo LDH–rGO/Ni F was developed by a solvothermal process for the first time. This material was fabricated through simultaneous growth of nickel–cobalt layered double hydroxide (NiCo LDH) and reduced graphene oxide (rGO) on nickel foam. This bulk composite can be used directly as a binder-free electrode for supercapacitors (SCs). The physicochemical properties of this composite were characterized by scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. The electrochemical properties of the composite were measured by the cyclic voltammetry and galvanostatic charge–discharge. The results show that this composite had a hierarchical structure and exhibited a significantly enhanced specific capacitance of up to 3383 F/g at 1 A/g. The asymmetric SC using this composite as a positive electrode had a high energy density of 40.54 Wh/kg at the power density of 206.5 W/kg and good cycling stability. Owing to the synergies between the metal oxides and the rGO, the preparation method of in situ growth and its hierarchical structure, this bulk composite displayed excellent electrochemical performance and had a promising application as an efficient electrode for high-performance SCs.