Construction and application in solid-state asymmetric supercapacitors of gladiolus-like NiSe/CoSe/Ni3Se2 hierarchical nanocomposite with synergistic structural advantages

Gladiolus-like NiSe/CoSe/Ni3Se2 hierarchical nanocomposite supported by nickel foams (NF) was synthesized for the first time by the mixed solvothermal method. Structural characterizations show that the obtained hierarchical nanocomposite forms from the dense growth of NiSe and CoSe nanosheets around Ni3Se2 nanowires. This novel gladiolus-like nanostructure supported by NF possesses the remarkable synergistic structural advantages from 1D/2D nanostructures and porous metallic substrate. It makes the gladiolus-like NiSe/CoSe/Ni3Se2 hierarchical nanocomposite with the excellent electrochemical properties, i.e.: high mass specific capacitance of 1666 F g−1 at 0.5 A g−1, high rate performance of 56.7 % at 2.5 A g−1, and 85.19 % capacitance retention after 5000 cycles. These phenomena are ascribled to the hierarchical nanostructure, heterozygous mettalic atoms, high conductivity, and significant synergistic effect. Subsequently, solid-state asymmetric supercapacitors are built up by using gladiolus-like NiSe/CoSe/Ni3Se2 hierarchical nanocomposite and active carbon as the pair electrodes. This solid-state device has a high areal energy density of 0.33 mWh cm−2 at areal power density of 7 mW cm−2, 80.11 % capacitance retention after 10,000 cycles, and promising commercial value. Thus, the present work not only demonstrates that gladiolus-like NiSe/CoSe/Ni3Se2 hierarchical nanocomposite is the promising electrochemical materials, but also offers a new device for solid-state, small, and smart electronic products. The present groundbreaking work also offers a novel strategy for enhancing the electrochemical capability of supercapacitor electrodes by designing ingenious nanostructures.