Fe3O4 doped double-shelled hollow carbon spheres with hierarchical pore network for durable high-performance supercapacitor

Double-shelled hollow carbon spheres with multiporosity, highly conductive graphite structure and Fe3O4 species was initially prepared (C-C-Fe3O4). The seamless combination between the Fe3O4 species and the porous carbon network leads to a remarkably high capacitivity (1153 F g−1 at 2 A g−1) and good rate capability (514 F g−1 at 100 A g−1) of pseudocapacitive. In addition, the C-C-Fe3O4 assembled asymmetric supercapacitor demonstrates excellent cycling stability (96.7% retention of the initial capacitance after 8000 cycles) and achieves high energy density (17-45 W h kg−1) at powder density of 400-8000 W kg−1. The unique porous carbon structure and seamlessly integration between carbon and Fe3O4 species generate synergistic effect to boost high performance and ideal durability, and high conductivity of the graphitized carbon, the large specific surface area of the hierarchical pore network and the perfectly distributed Fe3O4 redox species in the carbon content also account for its ideal capacitive properties. The multiporous structure could allow efficient diffusion of electrolyte and promote interfacial redox reactions of supercapacitor by facilitating the accessibility of redox active sites, and the highly uniform distribution of Fe3O4 species in the porous carbon makes the best use of conductive carbon network and facilitates good rate capability.