Fabrication of interconnected mesoporous carbon sheets for use in high-performance supercapacitors

Abstract

Interconnected mesoporous carbon sheets (IMCSs) for use in supercapacitors were fabricated from coal tar pitch using a metal-organic framework (MOF-5) template method combined with KOH activation. The samples were characterized by transmission electron microscopy, N2 adsorption, X-ray diffraction and X-ray photoelectron spectroscopy. Results show that the specific surface area of IMCSs is in the range of 860 to 1 046 m2 g−1. The IMCS prepared under the optimal conditions presents a high specific capacitance of 242 F g−1 at 0.05 A g−1 in a 6 M KOH aqueous electrolyte. It also exhibits an excellent rate capability with a 80.2% capacitance retention rate as the current density increases from 0.05 to 20 A g−1, and a cycle stability with a 94.2% capacitance retention rate after 10 000 charge-discharge cycles. The good electrochemical performance is ascribed to small hierarchical pores for ion fast transport, abundant accessible micropores for ion storage and interconnected structure for high electron conductivity. This work provides a simple method for the synthesis of IMCSs from cheap polycyclic aromatic hydrocarbons, including coal tar pitch and petroleum pitch, for use in high-performance supercapacitors.