Nauka /Interperiodica

particular, in a two-electrode prototype of a real lith-
ium-ion battery (the negative electrode of a carbon-
aceous material and the positive electrode of a lithiated
oxide of a transition metal). Possible, this explains the
considerable discrepancy between the results of many
works concerned with studying LIB (some authors
investigate a system as a whole, while others–individ-
ual electrodes).
PHENOMENOLOGY OF THE LIB CAPACITY 
FADING: THE LIB IMPEDANCE 
AS AN INDICATOR OF THE LIB WORKABILITY
According to information of the Japanese firm Sony
[53], a pioneer and acknowledged authority in the field
of LIB, the capacity of its LIB the size 26650 decreases
by 20% after 500 charge–discharge cycles, and the self-
discharge of LIB stored in ordinary conditions reaches
nearly 10% within three months. The loss of the capac-
ity of cylindrical LIB the size 18650 (diameter 18 mm,
height 65 mm, which are widely spread abroad) with
the cathode based on LiCoO
2
amounts to 10–18% after
500 cycles [54, 55]. During storage of charged batteries
there is observed an irreversible drop of the capacity;
moreover, an increase in the temperature during storage
and an increase in the degree of chargeness severely
affect the degree of the degradation. A three-month
storage of a fully charged battery (EMF 4.2 V) leads to
almost the same drop of the capacity (11%) as that after
500 charge–discharge cycles; as a result of a year-long
storage of fully charged batteries, the irreversible
capacity loss is 30% [55]. Tobishima 
 
et al.
[56] per-
formed tests of LIB 18650 (Sony) stored at 20 and
60°ë
. The voltage of half the batteries was potentiostat-
ically maintained at 4.2 V (fully charged batteries) and
that of the other half, at 4.1 V (partially discharged).
The capacity loss of the fully charged LIB stored for
one year at room temperature was 23%, out of which
18% were irreversible losses. A year-long storage at the
elevated temperature led to a decrease in the capacity of
LIB by 50%, with the irreversible degradation amount-
ing to 40%. The results of these tests showed that dur-
ing storage at room temperature, the decrease in the
degree of chargeness accelerates degradation of LIB,
whereas this factor is not that critical at elevated tem-
peratures.
The authors of [1] presented the results of studying
the possibilities of cylindrical (size 18650) and pris-
matic (size 103450) LIB produced by various Japanese
and European firms. After 300 charge–discharge cycles
at room temperature, the average discharge voltage
reduced by a mere 6%, whereas the energetic losses
amounted to ~21%.
The authors of [46] established that an increase in
the storage temperature by 
15°ë
leads to a twofold
decrease in the lifetime of LIB. The same effect was
registered when elevating the final voltage by 0.1 V
(when exploiting LIB in a regime of continuous
recharging).
Wright 
 
et al.
[42] analyzed the decrease in the
capacity and power of LIB the size 18650 with positive
electrodes based on multicomponent lithiated oxides
LiNi
0.8
Co
0.15
Al
0.05
O
2
and LiNi
0.8
Co
0.10
Al
0.10
O
2
and neg-
ative electrodes of graphite when cycled at 25 and
45°ë
. At 
25°ë
, the decrease in the power decreased
with time linearly, whereas at 
45°ë
, proportionally to
the root square of the cycling duration. The drop of the
power and the capacity of all the tested batteries (pro-
portionally to the root square of the cycling duration),
according to [42], was caused by the thickening and
modification of a layer of solid electrolyte (solid electro-
lyte interface) at the surface of electrodes and by modifi-
cation of properties of the separator.
Broussely