The porous structures of activated carbon aerogels and their effects on electrochemical performance

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• 作者：Junbing Wang ; Xiaoqing Yang ; Dingcai Wu ; Ruowen Fu ; Mildred S. Dresselhaus ; Gene Dresselhaus
• 关键词：Carbon aerogel ; Activation ; Porosity ; Electrochemical properties
• 刊名：Journal of Power Sources
• 出版年：2008
• 出版时间：15 October 2008
• 年：2008
• 卷：185
• 期：1
• 页码：589-594
• 全文大小：983 K

文摘

The pore structures of carbon aerogels were designed and controlled by changing conditions for both the microemulsion-templated sol–gel polymerization and the KOH activation processes. The resulting pore structures were characterized by means of N₂ adsorption and SEM. A new pore model is proposed and the relationship between the pore structures of the activated carbon aerogels (ACAs) and their electrochemical performance is discussed. The experimental results show that the ACAs which were prepared contain four types of pores: (A) micropores with diameters below 2 nm; (B) small mesopores with diameters from 2 to 5 nm; (C) large mesopores with diameters from 5 to 40 nm; and (D) large pores and channels with diameters over 40 nm. Appropriate activation with KOH can increase the numbers of micropores and small mesopores as well as the BET areas, resulting in an increase in the specific capacitance (C_s) of the ACA samples. The type D pores and channels play an important role in the enhancement of the electrochemical capacitance under high charge–discharge current conditions. Though ACAs with different porous models show a linear relation between C_s and BET area separately, the surface areas of micropores of the ACAs with appropriate type D pores and channels have a higher accessibility and efficiency in the storage of energy than those with closed type C pores.