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Capacitance behavior of KOH activated mesocarbon microbeads in different aqueous electrolytes

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Abstract.
A series of microporous carbons with wide scope of porosity development (surface area
SDFT = 1200–2460 m2 g−1, micropore volume VDR = 0.43–1.2 cm3 g−1, average micropore width
L0 = 0.9–1.5 nm) was prepared by KOH activation of coal-tar pitch derived mesocarbon microbeads
(MCMB). The activated MCMB were tested as an electrode material of capacitor in two-electrode system
operating in various aqueous electrolytic solutions using galvanostatic, voltammetry and impedance
spectroscopy techniques. The study shows that the capability of charge accumulation in electric
double layer is controlled primarily by electrolyte properties. Independent of porosity development the
capacitance of activated MCMB decreases in the order: 6 mol L−1 KOH, 1 mol L−1 H2SO4, 4.5 mol L−1 KCl,
2 mol L−1 KNO3 and 0.5 mol L−1 Na2SO4. The sequence corresponds basically to the solution conductivity.
Activated MCMB of moderate surface area (SDFT = 1450–1650 m2 g−1) and relatively narrow micropores
(L0 = 0.9–1.05 nm), which were produced from MCMB carbonized at 600–700 ◦C by activation at 700 ◦C
using 2:1 KOH/MCMB ratio, seem to be most promising electrode material. They demonstrate superior
both the gravimetric and volumetric capacitances (in 6 mol L−1 KOH 280–300 F g−1 and above 160 F cm−3,
respectively) and a good performance at the current density up to 20 A g−1. Apart from the suitable
pore size distribution, the specific particle morphology and a high extent of orientation of constituting
defective graphene layers seem to contribute to the superior capacitance properties of activated MCMB
compared to ordinary activated carbons.

Keywords: KOH activated mesocarbon microbeads; Porous texture; Aqueous electrolyte; Capacitance; Electrochemical capacitor; Double layer capacitor; EDLC

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Ketersediaan

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Informasi Detail

Judul Seri

Electrochimica Acta

No. Panggil

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Penerbit

New York : Elsevier Ltd.., 2012

Deskripsi Fisik

Electrochimica Acta 86 (2012) 260– 267

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

86 (2012)

Subjek

KAPASITOR ELEKTROKIMIA

Info Detail Spesifik

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Pernyataan Tanggungjawab

agus

Versi lain/terkait

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