Comparison of capacitive behavior of activated carbons with different pore structures in aqueous and nonaqueous systems |
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Authors: | Shao-yun Zhou Xin-hai Li Zhi-xing Wang Hua-jun Guo Wen-jie Peng |
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Affiliation: | School of Metallurgical Science and Engineering, Central South University, Changsha 410083, China |
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Abstract: | The pore structures of two activated carbons from sawdust with KOH activation and coconut-shell with steam activation for supercapacitor were analyzed by N2 adsorption method. The electrochemical properties of both activated carbons in 6mol/L KOH solution and 1mol/L Et4NPF4/PC were compared, and the effect of pore structure on the capacitance was investigated by cyclic voltammetry, AC impedance and charge-discharge measurements. The results indicate that the capacitance mainly depends on effective surface area, but the power property mainly depends on mesoporosity. At low specific current (1A/g), the maximum specific capacitances of 276.3F/g in aqueous system and 123.9F/g in nonaqueous system can be obtained from sawdust activated carbon with a larger surface area of 1808m2/g, but at a high specific current, the specific capacitance of coconut-shell activated carbon with a higher mesoporosity of 75.1% is more excellent. Activated carbon by KOH activation is fitter for aqueous system and that by steam activation is fitter for nonaqueous system. |
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Keywords: | activated carbon supercapacitor aqueous system nonaqueous system capacitance |
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