Abstract: In order to prepare activated carbons for supercapacitor electrode with low price and good performance, traditional steam activation method was employed to prepare activated carbons from masson pine wood. The elemental analyzer and the nitrogen adsorption/desorption were employed to analyze the element contents and pore structure of the activated carbons. The electrochemical performance of the activated carbon electrodes was examined by the methods including cyclic voltammetry, galvanostatic charge-discharge cycles and electrochemical impedance spectroscopy using 1-ethyl-3-methyl imidazole tetrafluoroborate/acetonitrile (EMIMBF₄/AN) as electrolytes. The effects of activation temperature and time on the electrochemical performance of activated carbon were investigated. The results showed that the specific copacitance of activated carbon increased first and then decreased with the increment of activation temperature and activation time. The activated carbon prepared at carbonization temperature 900℃ and activation temperature 900℃ for 1 h reached the maximum of the specific capacitance. Its specific capacitance reached 155 F/g with a sweep speed of 5 mV/s and remaind 105 F/g at 100 mV/s, and the energy density in organic electrolyte was as high as 33.6 (W·h)/kg. After 5 000 cycles, specific capacitance was remain at value of 89%.

Key words: steam activation, woody activated carbon, organic electrolyte, supercapacitor