Cobalt oxide nanocomposites modified by NiCo-layered double hydroxide nanosheets as advanced electrodes for supercapacitors

Abstract

Transition metal oxides with metallic composites are attractive for advanced electrodes due to their high capacitance, high conductivity, and low cost. Here, a multihierarchical structure (NiCo LDH/M Co3O4, M is the mass of Co3O4) of NiCo-layered double hydroxide (NiCo LDH) nanosheets uniformly grown on the surface cobalt oxide (Co3O4) is synthesized via a mild hydrothermal method. In particular, the NiCo LDH/50 mg Co3O4 nanocomposite material has the advantages of large specific surface area, wealthy aperture, high pseudo-capacitance, and small internal resistance. Electrochemical investigation reveals that the NiCo LDH/50 mg Co3O4 is rather outstanding, which delivers high energy density, long-life supercapacitor as a positive electrode material. It is worth mentioning that the specific surface area and specific capacitance of NiCo LDH/50 mg Co3O4 are threefolds and fivefolds that of pure Co3O4, respectively. The specific capacitance of NiCo LDH/50 mg Co3O4 is 1393.9 F g−1 at 1 A g−1 with outstanding cycle stability (88.4% up to 5000 cycles). The aqueous asymmetric supercapacitor (ASC) was assembled by employing the NiCo LDH/50 mg Co3O4 as positive electrode and activated carbon (AC) as negative electrode, which delivers a voltage window of 1.5 V and a high energy density of 46.4 Wh kg−1 at a power density of 750.4 W kg−1. These excellent properties make it a promising candidate in electrochemical energy storage materials.