Activated hierarchical porous carbon as electrode membrane accommodated with triblock copolymer for supercapacitors

Abstract

Homopolymer PAN and triblock copolymer PAN-b-PMMA-b-PAN synthesized by RAFT polymerization were used to fabricate activated hierarchical porous carbon membranes by combining phase inversion, carbonization, and HNO3 activation method; during the preparation process, a lot of micro- and meso-pores generated because of phase separation of PAN and microphase separation of PAN-b-PMMA-b-PAN. The hierarchical porous structure shortened ions transport paths and facilitated the rapid migration of electrolyte ions. When the polymer membrane was prepared by the casting solution with 5wt% of PAN-b-PMMA-b-PAN and the electrochemical performance was tested at the current densities from 0.5 to 5Ag−1, a high-end specific capacitance of 297.0Fg−1 and a capacitance retention of 75% were obtained in three-electrode configuration; this specific capacitance remained above 90% of initial value after 2000 cycles at 2Ag−1 in 6M KOH aqueous solution. Moreover, symmetric supercapacitors assembled with the prepared materials achieved high energy density (15.8WhKg−1) and power density (4000WKg−1) in 1M Na2SO4 solution. The unique features and structures endowed the electrode membrane with good capacitive performance in both three-electrode and two-electrode configuration, which can be used as electrode membranes for high-performance energy storage devices and other applications.