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

3 years ago

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

Panpan Chang, Mingming Chen, Masahiro Toyoda, Taro Kinumoto, Tomoki Tsumura, Chengyang Wang

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 m2 g−1, a high sp2-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 C10/0.05 of 56.8 % in TEABF4/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 TEABF4/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. No secret agent: A series of conductive hierarchical C/C composites are constructed. Totally different from the state-of the-art porous carbons with high specific surface area (SSA) but low electrical conductivity, the as-prepared C/C composites are of ample SSA, hierarchical pore structure, and adequate electrical conductivity. When used as a carbon-black-free electrode, they achieve high gravimetric specific capacitance, excellent rate performance, and outstanding long-term stability in both KOH aqueous and TEABF4/PC organic electrolytes.

Publisher URL: http://onlinelibrary.wiley.com/resolve/doi

DOI: 10.1002/celc.201700650