Synthesis of a hierarchical nanoporous carbon material with controllable pore size and effective surface area for high-performance electrochemical capacitors

Abstract

A simple carbonization procedure is proposed for the synthesis of hierarchical nanoporous carbons with controllable pore size and effective surface area as electrode materials for high-performance electrochemical double-layer capacitors. The procedure is based on the carbonization of interpenetrating polymer networks (IPNs) composed of cross-linked polystyrene (PS) and poly(methyl methacrylate) (PMMA). The as-obtained hierarchical nanoporous carbons (HNC-IPNs) have controllable pore size, interconnected pore structure, high specific surface area, excellent electrical conductivity and electrochemical stability with the different mass ratio of PS/PMMA. In addition, there is authentically an excellent linear relationship between effective specific surface area (E-SSA) and specific capacitance. Especially, the HNC-IPN-4 exhibits the highest specific surface area (SSA) of 1346 m² g⁻¹, relative high E-SSA of 603 m² g⁻¹, and excellent specific capacitance of 260 F g⁻¹ under the current density of 0.5 A g⁻¹ in 6 M KOH. Meanwhile, the HNC-IPN-4 exhibits a superior cycling performance without any degradation after 10 000 cycles with the current density of 2 A g⁻¹ as well as exhibits high capacitance retention, i.e., 96.0% of the initial specific capacitance after 20 000 cycles.