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 Sm-1. Even totally free of any CB, the resultant EDLC electrode achieved a high gravimetric capacitance of 130.4 Fg(-1) at 50 mAg(-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 Ag-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.