High performance supercapacitor based on polyaniline nanowire arrays grown on three-dimensional graphene with small pore sizes
Three-dimensional graphene (3D GR)-based hybrid has received a significant attention due to their unique structures and promising applications in supercapacitors. In this paper, 3D GR with small pore sizes is prepared by chemical vapor deposition using commercial nickel nanowires as the template. After nitric acid treatment, the hydrophilicity of 3D GR is improved. Polyaniline nanowire arrays (PANI NWAs) are successfully grown on its surface by in-situ polymerization to obtain the hybrid of PANI NWA/3D GR. The results show that PANI NWAs with the length of ～300 nm are vertically grown on 3D GR with a pore diameter of ～2 μm. The small pore size of the 3D GR not only improves the mechanical properties of the 3D GR, but also provides a lot of sites for the growth of PANI NWAs. Meanwhile, PANI NWAs provide a shorter ion diffusion path and a larger contact area with the electrolyte. Due to the unique structure, the hybrid exhibits a high specific capacitance of 789.9 F·g-1 at 10 mV·s-1. When it’s assembled into a symmetric supercapacitor, it exhibits an energy density of 32.2 Wh·kg-1 at a power density of 793.3 W·kg-1 and maintains a good cycle stability of 90% after 5000 cycles at 1.0 A·g-1.