sp²–sp³ Hybrid Porous Carbon Materials Applied for Supercapacitors

Abstract

Carbon materials have gained considerable attention in recent years due to their superior properties. Activated carbon has been used in supercapacitors due to its density and rapid adsorption capability. The sp2–sp3 hybrid porous carbon materials are synthesized using herringbone-type carbon nanofibers (CNFs) and carbonized spherical phenol resins, with KOH as the activating agent. The morphology of the hybrid porous carbon facilitates the formation of ribbon-like nanosheets from highly activated CNFs wrapped around spherical resin-based activated carbon. The etching and separation of the CNFs produce a thin ribbon-like nanosheet structure; these CNFs simultaneously form new bonds with activated carbon, forming the sp2–sp3 hybrid porous structure. The relatively poor electrical conductivity of amorphous carbon is improved by the 3D conductive network that interconnects the CNF and amorphous carbon without requiring additional conductive material. The composite electrode has high electron conductivity and a large surface area with a specific capacitance of 120 F g−1. Thus, the strategy substantially simplifies the hybrid materials of sp2-hybridized CNFs and sp3-hybridized amorphous spherical carbon and significantly improves the comprehensive electrochemical performance of supercapacitors. The developed synthesis strategy provides important insights into the design and fabrication of carbon nanostructures that can be potentially applied as electrode materials for supercapacitors.

Keywords

• supercapacitor
• carbon materials
• energy storage system
• carbon nanofiber
• activated carbon