ISSN 1070-4272, Russian Journal of Applied Chemistry, 2008, Vol. 81, No. 6, pp. 978!982. + Pleiades Publishing, Ltd., 2008.
Original Russian Text + R.D. Apostolova, L.I. Neduzhko, E.M. Shembel
, 2008, published in Zhurnal Prikladnoi Khimii, 2008, Vol. 81,
No. 6, pp. 939!943.
AND CORROSION PROTECTION OF METALS
Electrolytic Iron Sulfides in Prototype Lithium Batteries
with Gel Electrolytes Based on Poly(vinyliden fluoride)
and Its Derivatives
R. D. Apostolova, L. I. Neduzhko, and E. M. Shembel
Ukrainian State University of Chemical Engineering, Dnepropertovsk, Ukraine
Received May 16, 2007
Abstract-Electrolytic thin-film iron sulfide compounds were studied in prototype lithium batteries
with gel electrolytes based on poly(vinyliden fluoride) and its derivatives by the method of galvanostatic
cycling at room temperature. A discharge capacity of 2003280 mA h g
in 803180 cycles was obtained.
Transition-metal sulfides (M = Mo, Ni, Fe, etc.)
are widely used owing to their electrical, magnetic,
optical, catalytic, and other properties. Depending
on the intended use, M-sulfides are obtained as
micrometer or submicrometer particles, which may
be rod-like, spherical, and other amorphous or
crystalline formations and films . Films of
M-sulfides are attractive because they can provide
efficient electrochemical conversion in electrodes of
thin-film lithium and lithium-ion batteries [4, 5].
The demand for batteries of this kind is growing
because of the miniaturization of power sources
necessary for portable means of communication,
electronic devices, and other power consumers.
Among the numerous known film-formation
methods (magnetron, laser, and RF sputtering,
thermal evaporation in a vacuum, and electrode-
position), the electrolytic method was chosen for
synthesis of thin-film electrode materials for lithium
chemical power cells (CPC) .
Electrolysis has been used to obtain thin-film
molybdenum sulfides  and Fe sulfide compounds
(e-Fe,S) with a thickness of 3320 mm . Until re-
cently, iron sulfides (FeS, FeS
) have been used
in cathodes of lithium cells and in lithium batteries
of high-temperature type with a LiCl3KCl eutectic
and of medium-temperature type with solid poly-
meric electrolytes [9, 10]. It has been shown that
a reversible electrochemical transformation of nat-
ural pyrite is possible in gel electrolytes . At
the same time, only a minor fraction of the theo-
retical specific energy of natural pyrite (FeS
be obtained in cycling in a lithium CPC in pair
with a solar cell at room temperature . At
the same time, iron sulfide products of electrolysis
(e-Fe, S) can be considered suitable electrode
materials for low-temperature lithium batteries .
Their reversible capacity in electrochemical con-
version in an electrolyte composed of propylene
carbonate (PC), dimethoxyethane (DME), and 1 M
is 2003300 mA h g
(in 40350th cycles).
Because gel electrolytes are preferable to liquid
electrolytes for thin-film lithium batteries for en-
vironmental safety reasons, studies of the thin-film
e-Fe,S system were continued on prototype lithium
CPC with gel-like polymeric electrolytes.
The e-Fe,S compounds were deposited as com-
pact formations with a mass of 1.537.0 mg cm
on 10 0 10 0 0.1-mm aluminum alloy (AMG-6)
substrates by cathodic reduction of solutions con-
taining iron sulfate, sodium thiosulfate, and stabi-
lizing additives. The synthesis conditions have been
described in detail previously . The structure
of the compounds synthesized was determined by
an X-ray diffraction analysis (DRON-2.0 diffrac-
tometer, LiF single crystal as monochromator,
radiation). The radiation intensity was mea-
sured in the range 2q =10o380o.