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Preparation and Electrochemical Performance of Activated Carbon Made from Peanut Shell

Author: NiuShuZhang
Tutor: ZhuYuMei
School: Tianjin University
Course: Materials Science
Keywords: peanut shell activated carbon supercapacitor electrochemical properties
CLC: TM53
Type: Master's thesis
Year: 2009
Downloads: 71
Quote: 1
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Abstract

Supercapacitors have been recognized as unique energy storage devices which can provide energy densities higher than those of conventional electrolytic capacitors, and higher power density and longer cycle life than batteries, filling the gap between conventional dielectric capacitors and batteries. Thus, supercapacitors are widely applied in different fields, for example, power requirement, energy storage and composite systems including electrochemical capacitors and batteries.In this paper activated carbons with high surface area were prepared from peanut shells and ZnCl₂ as activator, and their capacitive performances were investigated in detail. The morphologies of the activated carbon were observed by scanning electron microscopy（SEM）.The specific surface area and pore structure were characterized by N₂ absorption/desorption isotherms. Their electrochemical performances in 6mol/L KOH aqueous and 1mo1/L Et₄NBF₄/PC electrolyte were evaluated by galvanostatic charge-discharge, cyclic voltammetry and impedance spectroscopy. Then, the effect of dipping proportion,activated tempreture and heating rate ware researched.Experimental results showed that the ZnCl₂ joined in the peanut shells obviously decreased the carbonization temperature, improved the pore structure, increased the surface of activated carbon and had no significant effect on the functional group of activated carbon .Activated carbons were prepared from peanut shells activated by ZnCl₂, along with the impregnation ratio from 1:1 to 4:1, the specific surface area of activated carbon derived from 540.1 m²/g up to 1205 m²/g, pore volume from 0.2339cm³/g up to 1.1150 cm³/g and average pore size from 1.732nm to 3.973nm.Activated carbons were prepared from peanut shells activated by ZnCl₂,along with the activation temperature from 500℃to 800℃, the specific surface area of activated carbon derived from 1143 m²/g down to 930.7 m²/g, pore volume from 1.0360 cm³/g reduced to 0.8625 cm³/g, average pore diameter rose from 3.624nm to 3.988nm.Activated carbons were prepared from peanut shells activated by ZnCl₂, along with the heating rate improved from 3℃/min to 5℃/min and then increased to 10℃/min, the specific surface area of activated carbon derived from 937 m²/g to 979 m²/g and then fell to 940m²/g , pore volume rose from 0.8820 cm³/g to 0.9592 cm³/g and then fell to 0.6173 cm³/g, average pore size rose from 3.768nm to 3.916nm and then in the reduced to 2.626nm. Peanut shells-based activated carbon prepared at 500℃for 2h had surface area as high as 1143m²/g with mesoporosity ratio of 29.40%.Its capacitance in aqueous electrolyte reached 199.2 F/g and the internal resistance reached 1.5Ωwith good rate performance. The sample prepared at 500℃for 2h had the highest capacitance of 70.81F/g and the internal resistance reached 5.2Ωin 1mo1/L Et₄NBF₄/PC electrolyte.

Preparation and Electrochemical Performance of Activated Carbon Made from Peanut Shell

Abstract

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