CARBONLETT, vol. 22, no. 1, pp.70-80, 2017

DOI: http://dx.doi.org/10.5714/CL.

High-energy-density activated carbon electrode for organic electric-double-layer-capacitor using carbonized petroleum pitch

Poo Reum Choi¹, Sang-Gil Kim², Ji Chul Jung^1,♠ and Myung-Soo Kim^1,♠

Affiliation: ¹Department of Chemical Engineering, Myongji University, Yongin 17058, Korea
²R&D Center, Vitzrocell Co. Ltd., Yesan 32417, Korea

Abstract: Activated carbons (ACs) have been used as electrode materials of electric double-layer capacitors (EDLC) due to their high specific surface areas (SSA), stability, and ecological advantages. In order to make high-energy-density ACs for EDLC, petroleum pitch (PP) precarbonized at 500-1000°C in N₂ gas for 1 h was used as the electrode material of the EDLC after KOH activation. As the pre-carbonization temperature increased, the SSA, pore volume and gravimetric capacitance tended to decrease, but the crystallinity and electrode density tended to increase, showing a maximum volumetric capacitance at a medium carbonization temperature. Therefore, it was possible to control the crystalline structure, SSA, and pore structure of AC by changing the pre-carbonization temperature. Because the electrode density increased with increasing of the pre-carbonization temperature, the highest volumetric capacitance of 28.4 F/cc was obtained from the PP pre-carbonized at 700°C, exhibiting a value over 150% of that of a commercial AC (MSP-20) for EDLC. Electrochemical activation was observed from the electrodes of PP as they were pre-carbonized at high temperatures above 700°C and then activated by KOH. This process was found to have a significant effect on the specific capacitance and it was demonstrated that the higher charging voltage of EDLC was, the greater the electrochemical activation effect was.

Keyword: activated carbon, petroleum pitch, EDLC, electrochemical activation, volumetric capacitance