Influence of pore symmetries on the supercapacitive performance of mesoporous carbons co-templated by F127 and PDMS-PEO

摘要

In the present study, the mesoporous carbons (MPCs) with 2D hexagonal (p6m) and three-dimensional (3D) body-centered cubic (Im (3) over barm) symmetry were synthesized by using triblock copolymer PEO-PPO-PEO (F127) and diblock copolymer polydimethylsiloxane-poly(ethylene oxide) (PDMS-PEO) as co-templates. Common activating agent KOH was further utilized to improve the surface area and micropore volume of the MPCs. Their electrochemical performance as electrode materials for supercapacitors was investigated by cyclic voltammetry, galvanostatic charge-discharge tests and electrochemical impedance spectroscopy. It was found that the supercapacitive performance of 2D p6m mesoporous carbon was superior to that of 3D Im (3) over barm mesoporous carbon because 2D cylindrical mesopores facilitated the faster ion transfer along their smooth channels than within the isolated pores of 3D cubic mesopores. Compared to the pristine mesoporous carbons, the activated samples exhibited notable enhancements in specific capacitances because the micropores produced by KOH activation made the isolated pores interconnect to each other, thus providing more entrances for electrolyte diffusion and also shortening the diffusion distance. The activated sample with 2D p6m symmetry (A-2D-MPC) exhibited the highest specific capacitance of 226.3 F g(-1) in 6 M KOH at the current density of 1 A g-1. (C) 2014 Elsevier Inc. All rights reserved.