Highly Conductive Hierarchical C/C Composites to Eliminate Conductive Agent in EDLC Electrodes

Nowadays, when fabricating electric double‐layer capacitor (EDLC) electrodes, 10–20 % conductive carbon black (CB) is indispensable to guarantee a satisfactory power output of the whole EDLC. Herein, we constructed a series of porous frame‐filling C/C composites with ample specific surface area (SSA) and adequate electrical conductivity ( e ‐conductivity), aiming at CB‐free EDLC electrodes. The content of the frame and KOH dosage were well‐optimized to balance the SSA and e ‐conductivity. An optimized sample, named F310 exhibits an abundant SSA of 2562 m 2  g −1 , a high sp 2 ‐bonding carbon content of 88.2 %, and sufficient e ‐conductivity of 120 S m −1 . Even totally free of any CB, the resultant EDLC electrode achieved a high gravimetric capacitance of 130.4 F g −1 at 50 mA g −1 with a rate capacity C 10/0.05 of 56.8 % in TEABF 4 /PC electrolyte. Significantly, it could also run independently up to 10,000 cycles at 1 A g −1 with a capacitance retention of 78.3 % in TEABF 4 /PC electrolyte. More importantly, when the CB‐free electrode is in use, the lifespan at a stable high‐rate output is clearly decided by the e ‐conductivity rather than the mesoporous channels.