| In this paper, the high specific surface area activated carbon (HSAAC) was prepared from mesocarbon microbeads (MCMB) by the activation of KOH. The influences of the weight ratio of KOH to MCMB, the velocity of pyrogenation, the activation temperature and activation time on yield, powder specific resistance, adsorption properties and pore structure of activated mesocarbon microbeads had been systematically investigated. Based on these, the technologic methods and conditions which the pore structure and properties of activated mesocarbon microbeads were established. After analyzing the effects of the activation conditions on BET specific surface area and pore structure, the activation mechanism of KOH and the process of pore formation were discussed by use of SEM, XRD, DSC and energy spectrum analysis. Activated mesocarbon microbeads were used as electrode materials of electric double-layer capacitor (EDLC), its performance in 30wt% KOH electrolyte was determined by DC charge-discharge, cyclic voltammetry and AC impedance. The effects of activation conditions on specific capacitance, equivalent series resistance(ESR) and frequency response properties were investigated. Furthermore, the relations between the pore structure and the properties mentioned above were discussed.The analysis of activation mechanism shows that, there are two aspects of reaction such as activation and carbonization resisting in course of activation of MCMB by KOH. During carbonization, the polymerized flat aromatic molecules of microbeads grow and synchronously transform into hexangular-plane carbon layer. Meanwhile, the activation is an oxidation-reduction reaction which turns C into K2CO3. Due to the unique"globe-like"(Brooks-Taylor) structure, anisotropy is obviously observed in activation process. It means that pores are much easier to form and develop in the parallel direction of carbon layer compared with the vertical direction.Experiment results show that, compared to being mixed with KOH solid powder, the BET specific surface area, total pore volume and value of iodine absorption were enhanced when MCMB was mixed with KOH solution before activation. Moreover, the specific capacitance and yield of activated mesocarbon microbeads were also increased. The KOH/MCMB weight ratio, activation temperature and activation time are the main factors which influence the structure and performance of activated mesocarbon microbeads. When KOH/MCMB weight ratio, activation temperature and activating time increased, the BET specific surface area, total pore volume and value of iodine absorption increase firstly and then decrease. However, the yield of activated mesocarbon microbeads decreases gradually with the increasing of these factors. However, the velocity of pyrogenation and concentration of solution have a little influence on structure and performance.The optimum process conditions of preparing activated mesocarbon microbeads are KOH/MCMB ratio of 5, activation temperature at 850℃and activation time for 1 hours. When at the optimum process conditions mentioned above, the activated mesocarbon microbeads'BET specific surface area reaches 3337.2m~2/g, and its total pore volume and iodine absorption value are 2.04cm~3/g, 2705.2 mg/g respectively. The value of BET specific surface area, total pore volume and iodine absorption are much higher than those of HSAAC based on anthracite or petroleum coke. Moreover, activated mesocarbon microbeads have high mesopore content (41.2%) which is benefit for using as electrode materials of EDLC. Using activated mesocarbon microbeads as electrode materials, the specific capacitance of electrode in 30wt% KOH electrolyte reaches 88.3 F/g. This EDLC has good cycle performances and excellent properties of frequency response. It can charge-discharge not only under the small current and long time, but also under the large current and short time. In addition, its internal resistance and drain current are very small, so can suit with different practical application.
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