Russian Journal of Applied Chemistry, 2010, Vol. 83, No. 10, pp. 1811−1815.
Pleiades Publishing, Ltd., 2010.
Original Russian Text
S.P. Kuksenko, I.O. Kovalenko, 2010, published in Zhurnal Prikladnoi Khimii, 2010, Vol. 83, No. 10, pp. 1672−1676.
AND CORROSION PROTECTION OF METALS
Synthesis of a Silicon–Graphite Composite for the Hybrid
Electrode of Lithium–Ion Batteries
S. P. Kuksenko and I. O. Kovalenko
Chuiko Institute of Surface Chemistry, National Academy of Sciences of Ukraine, Kiev, Ukraine
Received November 23, 2009
Abstract—Comprehensive analysis was made of the cycling parameters (reversible speciﬁ c capacity, Coulomb
efﬁ ciency of cycles, accumulated irreversible capacity, and retention of reversible capacity) of a hybrid electrode
based on a mixture of MAG synthetic graphite and silicon–graphite composite produced by mechanical grinding.
At present, considerable researchers’ efforts are
aimed at improving the service characteristics of
lithium-ion batteries (LIBs) [1, 2]. To satisfy the demand
for LIBs with high energy and power, intensive studies
with lithium alloys are being carried out. Aluminum, tin,
and silicon electrochemically form alloys with lithium,
which have a substantially higher reversible capacity,
compared with the conventionally used carbon materials.
After a report  about the industrial manufacture by
Sony Corp. of a new generation of LIBs of the type
Nexelion 1443W1 (speciﬁ c energy of 478 W h dm
with a hybrid negative electrode composed of equal
mass fractions of graphite and amorphous phase of the
CoSn alloy, the idea to use lithium alloys has received
an additional stimulus for its development.
Of particular interest are silicon-carbon composite
materials [4–13] in which uniformly distributed
active silicon has a good mechanical adherence to
the electrically conducting and electrochemically
active carbon matrix, with the adhesion of silicon to
this matrix preserved even under a strong mechanical
stress produced by alternating processes of lithium
Until now, high cycling parameters could be only
obtained with sputtered thin-ﬁ lm silicon-carbon
composite electrodes [8–10]. However, their industrial
manufacture is hindered by economical factors. Of
considerable interest are classical “pasted” powder-
based electrodes. In this context, attention should be
given to a method of intensive mechanical grinding of
silicon in a mixture with graphite [4–7, 12], because
this method enables easy production of composites with
homogeneous structure and controlled composition and
fraction-grain size of the constituent powders.
The goal of earlier studies [4–7] was to obtain
nanosize silicon by high-speed grinding, with mixtures
with low content of silicon used for this purpose. As
a result, opinion has been formed  that composites with
silicon and carbon (both nanosize) provide considerably
better electrochemical parameters and cycling stability
of electrodes, compared with composites constituted
by micrometer particles. However, it was ignored that
the chemical interaction of the active electrode material
with the organic electrolyte is enhanced because of
the larger electrode/electrolyte contact area and high
surface energy of nanoparticles, and this leads, with
each subsequent cycle, to an excessive rise in such
an important cycling parameter as the accumulated
irreversible capacity [14, 15].
To combine the advantages of silicon and graphite:
the very high reversible capacity and high Coulomb
efﬁ ciency of cycles, we used in this study mechanical
grinding to produce silicon–graphite composites with
comparatively high content of silicon and minimum
changes in the morphology of graphite and fabricated
a hybrid electrode from a mixture of synthetic graphite
with a minor amount of the composite. The reversible
speciﬁ c capacity and retention of the reversible capacity
of the hybrid electrode were analyzed together with the
irreversible capacity accumulated in prolonged cycling.