Double‐activated porous carbons for high‐performance supercapacitor electrodes

Abstract The double‐activated porous carbons (DAPCs) with unique bimodal pore structure were prepared by activating commercial microporous carbon (CMCs) twice through KOH (double activation) at high temperature. The as‐prepared DAPCs show larger surface area (833 m 2 ·g −1 ), and the pores are composed of micropores (size of ~1.8 nm) and mesopores (size of ~4.5 nm). Such special hierarchical porous structures integrate the dual advantages of micropore and mesopore, having not only the high energy storage of the micropores but also the high‐rate performance of the mesopores for supercapacitors (SCs). As a result, the optimized DAPCs‐3‐1 exhibits a high specific capacitance of 277 F·g −1 at 1 A·g −1 , enhanced rate performance of 197 F·g −1 at a high current density of 10 A·g −1 , and excellent cycling stability with 94.2% capacity retention after 10,000 cycles in the 1 mol·L −1 Na 2 SO 4 electrolyte. The facile double activation could be a promising method to prepare suitable porous carbons with exceptional electrochemical properties for SCs.