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Asymmetric capacitance response from the chemical characteristics of activated carbons in KOH electrolyte

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Abstract.
The positive and negative capacitance behaviors of heat-treated activated carbons are separately studied
in a three-electrode configuration using 6 M KOH and 1 M H2SO4 as electrolytes. Heat treatment of activated
carbons at 400–800 oC causes slight changes in surface area accompanied by a significant removal
of oxygen-containing functional groups. Consequently, the specific surface capacitance with a 25% reduction
in the negative and an 8% reduction in the positive are monitored in KOH electrolyte. The unequal
capacitance reductions as well as the asymmetric CV curves reveal that the negative pseudo-capacitances
are much larger than the positive ones in KOH electrolyte. These results could be ascribed to the redox
reactions preferring in the negative region. The insertion process of cation also plays a significant effect
on the asymmetric capacitance behavior. Compared with the identical electrochemical response in H2SO4
electrolyte, huge difference in the capacitance values of both electrodes in KOH electrolyte will give a less
contribution to the cell capacitance. To optimize the cell performance, a suitably increasing the weigh of
active materials in the positive, especially for activated carbon with high level of oxygen-containing functional groups, is recommended.

Keywords: Electrochemical capacitors; Oxygen-containing functional groups; Pseudo-capacitance; Inorganic electrolyte; Asymmetric capacitance response

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Ketersediaan

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Informasi Detail

Judul Seri

Journal of Electroanalytical Chemistry

No. Panggil

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Penerbit

New York : Elsevier B.V.., 2011

Deskripsi Fisik

Journal of Electroanalytical Chemistry 659 (2011) 161–167

Bahasa

English

ISBN/ISSN

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Klasifikasi

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Tipe Isi

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Tipe Media

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Tipe Pembawa

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Edisi

659 (2011)

Subjek

KAPASITOR ELEKTROKIMIA

Info Detail Spesifik

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Pernyataan Tanggungjawab

agus

Versi lain/terkait

Lampiran Berkas

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