Preparation of phenanthrenequinone modified porous carbon nanotube composite material for symmetric supercapacitor

In purpose of obtaining electrode materials with superior electrochemical properties for supercapacitor, porous carbon nanotubes (PCNTs) were firstly prepared by the carbonization and activation of polypyrrole (PPy) nanotubes. The obtained PCNTs were further modified with 9,10-phenanthrenequinone(PQ) molecules via π-π stacking interaction through one-step solvothermal method. The electrochemical performance of the obtained composites (PQ/PCNTs) with different mass ratios of PQ to PCNTs as the electrode materials for supercapacitors were investigated by cyclic voltammetry (CV), galvonostantic charging-discharging (GCD) and electrochemical impedance spectroscopy (EIS). The experimental results show that the composites with the mass ratio of PQ molecule to PCNTs of 5∶5 achieves the largest specific capacity of 407.7 C∙g⁻¹ at a current density of 1 A∙g⁻¹. The resultant composite also exhibits excellent rate capability (the specific capacity at a current density of 50 A∙g⁻¹ is equal to 307.3 C∙g⁻¹) and cycling stability (capacitance retention of 91.4% after 10,000 cycles at the current density of 10 A∙g⁻¹). Furthermore, a symmetric supercapacitor was assembled with the mass ratio of PQ molecule to PCNTs of 5∶5 as electrode materials to investigate the practical applications of the composites. And the assembled symmetric supercapacitor delivers an energy density as high as 21.5 W∙h∙kg⁻¹ and a power density of 0.8 kW∙kg⁻¹.