The influence of nitric acid oxidation on the electrochemical performance of asphaltene-based ordered mesoporous carbon

Asphaltene-based ordered mesoporous carbon (OMC) was oxidized with 5mol/L nitric acid at 40-100℃. The influence of nitric acid oxidation treatment on its textural properties and electrochemical performance as a supercapacitor electrode material was investigated and the ionic transport behavior in relation to surface chemical structure was discussed. The pore structures and electrochemical performance were examined using XRD, nitrogen adsorption and an electrochemical workstation. Results indicate that electrochemical performance can be improved with nitric acid treatment under mild conditions. The regular mesostructure can be retained, and the surface areas and pore volumes vary slightly when oxidation temperature is below 60℃. A capacitor assembled with the OMC sample oxidized at 60℃ exhibits excellent electric double layer behavior, improved frequency response characteristics and a fast charge-discharge rate with a time constant of 6s. The gravimetric specific capacitance and energy density of OMC oxidized at 60℃ are 138F · g^-1 and 3.9Wh · kg^-1 respectively at a scanning rate of 5mV · s^-1. These values are respectively 57% and 63% greater than for the un-treated one.