Electrochemical performance of electric double layer capacitor by addition of nano-carbon into activated carbon electrode

摘要

Nano-carbon (NC) was synthesized by arc discharge in a semi-continuous process in different medium. Electric double layer capacitors (EDLCs) were fabricated for the first time with pristine NC or the addition of NC to the activated carbon (AC) electrode as conducting material to decrease the resistance of EDLCs. The electrochemical performance of the NC/AC composite is systematically investigated using cyclic voltammetric, discharge at constant current and electrochemical impedance spectroscopic (EIS) techniques. The results showed that specific capacitance (Csp) of NC synthesized in pure N2 is bigger than that synthesized in C2H2/N2 medium and the Csp of NC from arc chamber is far bigger than that from cooling chamber while the average internal resistance (Ri) of the former are both lower than that of the latter. Field emission scanning electron microscope (FE-SEM) observation reveals that the diameter of NC from arc chamber synthesized in pure N2 medium (NCN2ArcChamber) ranges from 80 to 100 nm while the diameter of AC is in the range of 1 to 5 μm. Thus, NCN2ArcChamber is selected and added to the AC electrode. EDLC using NCN2ArcChamber/AC composite showed a lower Ri of 0.46 Ω comparison to the pure NCN2ArcChamber or AC while the Csp of NCN2ArcChamber/AC composite increased with increasing AC content in NCN2ArcChamber/AC composite. The above results show that NCN2ArcChamber might be one of the suitable conducting materials to decrease the resistance of EDLC while maintaining its higher Csp.