ISSN 1070-4272, Russian Journal of Applied Chemistry, 2016, Vol. 89, No. 5, pp. 1000−1008. © Pleiades Publishing, Ltd., 2016.
The text was submitted by the authors in English.
Electric double layer capacitors (EDLCs), also known
as supercapacitors, occupy an intermediate position
between batteries, which have high energy density, and
high-power dielectric capacitors . Main advantages
of EDLCs compared with traditional energy storage
devices are high power (>10
), long cycle life
(more than 500k charge/discharge cycles), wide operating
temperature range (–25…+70°), low internal resistance
The operating principle of supercapacitors is based on
the charge/discharge of electric double layer and their
capacitance depend on the ionic conductivity of an
electrolyte as well as on the surface properties of an
electrode material [1, 8, 9]. An electrochemical process in
the EDLC can be represented by the following equation,
2E + C
where E, E
is the discharged, positively and
negatively charged surface of a porous electrode material,
are the cations and anions of the
electrolyte, respectively, || is the electric double layer
where charge is accumulated by means of physical and
chemical sorption .
The capacitance and power of the EDLCs depends
strongly on the surface area and porosity of the electrode
material. Therefore their electrodes are usually fabricated
using porous carbon materials of the high speciﬁ c surface
area (>1000 m
), e.g. activated carbons (ACs), carbon
aerogels, nanotubes, nanoﬁ bers, etc. [9–12].
More organic electrolytes for supercapacitors are
solutions containing quaternary ammonium salts in
acetonitrile or propylene carbonate (PC). As a result,
this enables one to achive high rated voltage (2.7–2.8 V)
[13–15]. Futhermore, the voltage range can be increased
up to 3 V just changing the electrode mass ratio .
An analysis of literature sources [17–19] has showed
that recently substituted ammonium salts of bis(oxalato)-
borate acid, which can be described by general formula
NBOB (where R is the alkyl radical, e.g. methyl Me,
ethyl Et, buthyl Bu, etc.), ﬁ nd a wide application as
electrolytes for EDLCs because they have high solubility
in aprotic solvents, achieve the wide potential range of
electrochemical stability and are relatively inexpensive.
Cation size affects the thermal stability of these salts:
NBOB decomposes at 215° without pre-melting,
Electrochemical Behavior of Activated Carbon Electrodes
in Electric Double Layer Capacitors with Tetrametylammonium
Bis(oxalato)borate Electrolyte Synthesized
by Microwave Irradiation
N. I. Globa*, O. B. Pushyk, D. G. Gromadskyi, O. I. Milovanova, and S. A. Kirillov
Joint Department of Electrochemical Energy Systems, 38A Vernadsky ave., 03142, Kyiv, Ukraine
Received June 10, 2016
Abstract—The electrochemical behavior of electric double layer capacitors (EDLCs) with tetramethylam-
monium bis(oxalato)borate electrolyte and electrodes based on various activated carbons (ACs) was studied.
Tetraalkylammonium bis(oxalate)borate salts were synthesized by means of microwave (MW) irradiation. The
speciﬁ c conductivities of salt solutions were determined. It was shown that the efﬁ ciency of electric double layer
capacitors increases with an increase in speciﬁ c surface area and a decrease in the purity of carbon materials.