Preparation of Wood Activated Carbon for Supercapacitor by Steam Activation

• 1、 College of Chemical Engineering，Nanjing Forestry University，Nanjing 210037 State Key Laboratory of chemistry and utilization of agriculture and forestry biomass in Jiangsu Province,Nanjing 210037

Abstract：In order to prepare activated carbon for supercapacitor electrodes with low price and excellent performance, Masson pine was activated by conventional steam activation method. The element contents and pore structure of the activated carbon was analyzed by the elemental analyzer and the nitrogen adsorption desorption instrument. The electrochemical performance of the electrode materials was measured by the method of cyclic voltammetry, galvanostatic charge-discharge cycles and electrochemical impedance spectroscopy in a 1- ethyl -3- methyl imidazole tetrafluoroborate/acetonitrile electrolyte. And the effects of carbonization temperature, activation temperature and activation time on the electrochemical properties of wood activated carbon were investigated. The results showed that: when the carbonization temperature was 900℃, the surface area of the char reached the maximum value of 703 m2/g. When the activation time was constant, the specific capacitance of the activated carbon increased first and then decreased with the increasing of the activation temperature; When the activation temperature was constant, the changing trend of the specific capacitance was the same as the former. The results of the electrochemical test showed that: When the carbonization temperature was 900℃, the activation temperature was 900℃, and the activation time was 1 h, the activated carbon can get a highest specific capacitance of 155F/g with a sweep speed of 5mv/s. Moreover, it showed good rate capability (105F/g remained at 100mv/s) andgood cycling stability (89% capacitance retention over 5000 cycles), and the energy density in organic electrolyte was as high as 33.4Wh/Kg.

Keywords： steam activation, wood activated carbon, organic electrolyte, supercapacitor