ISSN 1070-4272, Russian Journal of Applied Chemistry, 2006, Vol. 79, No. 4, pp. 602!604. + Pleiades Publishing, Inc., 2006.
Original Russian Text + N. D. Ivanova, O. A. Stadnik, 2006, published in Zhurnal Prikladnoi Khimii, 2006, Vol. 79, No. 4, pp. 611!613.
AND CORROSION PROTECTION OF METALS
Kinetics of Electrooxidation of Co(II) Ions
in a Fluorine-containing Electrolyte
N. D. Ivanova and O. A. Stadnik
Vernadsky Institute of General and Inorganic Chemistry, National Academy of Sciences of the Ukraine, Kiev, Ukraine
Received June 16, 2005; in final form, December 2005
Abstract-The electrochemical oxidation of Co(II) ions in fluorine-containing electrolytes on stationary
and rotating disc electrodes was studied.
In recent years [1,2], thin-film chemical power
sources (CPs) have been actively developed. CPs are
rather widely used in various electronic circuits, min-
iature batteries with high specific electrical charac-
teristics, displays, integrated circuits, high-quality
amplifiers, etc. Thin-film cathodes are promising for
development of rolled CPss, which have high specific
capacity. There are great expectations for application
of disordered nanostructure electrode materials .
The disordered structure ensures a high rate of in-
troduction of cations (lithium, hydrogen, etc.) into
the cathode mass.
Cobalt oxides find increasing use in batteries, for
making higher their voltage, and in thin-film CPss
, which poses the question of their manufacture.
Pyrolytic and chemical methods are known, as well
as the electrochemical technique involving oxidation
of metallic cobalt at a constant anodic polarization .
A sufficiently simple method has been developed for
synthesis of oxide compounds, including cobalt ox-
ides, from fluorine-containing electrolytes via incom-
plete oxidation3reduction .
The aim of this study was to synthesize oxide com-
pounds of cobalt by the electrochemical method and
to determine the kinetics of this process.
We used in the study solutions containing 103
30 g l
cobalt sulfate heptahydrate and 203 40 g l
ammonium fluoride. The current3voltage depen-
dences were studied on a PI-50-1.1 potentiostat with
an LKD-4 XY-recorder. The potential sweep rate was
. Platinum pressed into polyethylene
served as a working electrode (0.13 cm
) and a 4 cm
platinum plate, as a cathode.
The mass-transfer components were determined
by the method of a rotating disc electrode (RDE).
The same solutions as in the preceding case were
used in the study, with and without a supporting elec-
trolyte (1 M solution of sodium sulfate). The rate
of disc rotation was varied within the range 2003
600 rpm, which corresponds to 255 < Re < 766 .
At the disc rotation rates chosen, convective diffu-
sion can be disregarded. A saturated calomel electrode
(SCE) served as reference in both cases. All the poten-
tials in Figs. 134 are given relative to a standard
To determine the diffusion coefficient, the viscos-
ity of working solutions was evaluated using a cap-
illary viscometer as the ratio of the times of gravity
Fig. 1. E!log j dependences obtained for electrolytes of
different compositions. ( j ) Current density. Curve numbers
correspond to electrolyte numbers in Table 1; the same
for Figs. 2 and 4.