Polyaniline nanowire arrays on three-dimensional hollow graphene balls for high-performance symmetric supercapacitor

Three-dimensional graphene-based hybrid is a promising supercapacitor electrode material. Herein, a novel hybrid of polyaniline nanowire array/three-dimensional hollow graphene balls (PANI NWA/3D HGBs) is prepared. Three-dimensional hollow graphene balls (3D HGBs) are first fabricated by template-oriented carbon segregation and then polyaniline nanowire arrays (PANI NWAs) are grown on their surface by in-situ polymerization of aniline monomers. The results show that PANI NWAs with the length of ∼200 nm are vertically grown on 3D HGBs with a diameter of ∼500 nm. 3D HGBs act as the stable skeleton during long-term cyclic testing, and PANI NWAs provide a larger contact area with the electrolyte and a direct ion diffusion path. The hybrid exhibits a high specific capacitance of 635 F⋅g⁻¹ at 1 A⋅g⁻¹. When it's assembled into a symmetric supercapacitor, it exhibits an energy density of 25.3 Wh⋅kg⁻¹ at a power density of 553.4 W⋅kg⁻¹ and maintains a good cycle stability of 89% after 5000 cycles at 1.0 A⋅g⁻¹.