Activation of Petroleum Pitch for Production of Porous Carbons with High Electric Double Layer Capacitance

Abstract

Petroleum pitch can be an alternative of coal tar pitch as the precursor of activated carbon because of their lower contents of detrimental impurities and less pollution to the environment when compared with coal tar pitch. High-porosity carbon derived from activation of mesophase pitch with KOH has been successfully used as the electrode materials for electric double layer capacitors (EDLCs).1 Formation of mesophase structure through thermal treatment coordinates the pitch molecules and eventually reinforces the structure of porous carbons obtained from activation. The present study devises a temperature-programmed heating strategy to convert petroleum pitch to mesophase that has a framework advantageous for producing porous carbons suitable for EDLCs. The porous carbon is synthesized by KOH activation and has a Brunauer-Emmett-Teller surface area exceeding 3000 m2/g, When assembled in a symmetric two-electrode cell, the carbon delivers capacitance values of 170 and 102 F g-1 at current densities of 0.5 and 100 A g-1, respectively, in 1 M tetraethylammonium tetrafluoroborate/acetonitrile electrolyte. The energy density of the cell based on the total carbon mass reaches 23 Wh kg- 1 at a power density of 40 kW kg- 1. The results of the present study demonstrate the feasibility of using petroleum pitch as the precursor for porous carbon production and the significance of mesophase pitch structure for regulating the structure of pores suitable for charge storage.