СТРУКТУРНІ, ПОВЕРХНЕВІ ТА ЕЛЕКТРОХІМІЧНІ ХАРАКТЕРИСТИКИ TiO2 ДЛЯ ВИКОРИСТАННЯ В ЛІТІЙ-ІОННИХ АКУМУЛЯТОРАХ
The paper presents structural, surface, thermodynamic and kinetic characteristics of titanium dioxide samples obtained by means of alkaline hydrolysis of TiCl4 by LiOH solutions and further heat treatment. TiO2 samples have the anatase structure with crystallite size of 7–10 nm. An incr...
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| Дата: | 2020 |
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V.I.Vernadsky Institute of General and Inorganic Chemistry
2020
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Репозитарії
Ukrainian Chemistry Journal| _version_ | 1871465621329281024 |
|---|---|
| author | Globa, Nataliy Lisnycha, Tatyana Shmatok, Yurii Sirosh, Vitalii Kirillov, Sviatoslav |
| author_facet | Globa, Nataliy Lisnycha, Tatyana Shmatok, Yurii Sirosh, Vitalii Kirillov, Sviatoslav |
| author_institution_txt_mv | [
{
"author": "Nataliy Globa",
"institution": "Joint Department of Electrochemical Energy Systems, NAS of Ukraine"
},
{
"author": "Tatyana Lisnycha",
"institution": "Joint Department of Electrochemical Energy Systems, NAS of Ukraine"
},
{
"author": "Yurii Shmatok",
"institution": "Joint Department of Electrochemical Energy Systems, NAS of Ukraine"
},
{
"author": "Vitalii Sirosh",
"institution": "Joint Department of Electrochemical Energy Systems, NAS of Ukraine"
},
{
"author": "Sviatoslav Kirillov",
"institution": "Joint Department of Electrochemical Energy Systems, NAS of Ukraine"
}
] |
| author_sort | Globa, Nataliy |
| baseUrl_str | https://ucj.org.ua/index.php/journal/oai |
| collection | OJS |
| datestamp_date | 2026-07-22T08:23:44Z |
| description | The paper presents structural, surface, thermodynamic and kinetic characteristics of titanium dioxide samples obtained by means of alkaline hydrolysis of TiCl4 by LiOH solutions and further heat treatment. TiO2 samples have the anatase structure with crystallite size of 7–10 nm. An increase in the heat treatment temperature from 150 °C to 470 °C leads to a decrease in the specific surface area from 404 to 80 m2/g and the total pore volume from 0.340 to 0.152 cm3/g. The influence of electrolyte composition and surface properties of TiO2 on its behavior in cells with lithium anode investigated by means of galvanostatic cycling and impedance spectroscopy is discussed. |
| doi_str_mv | 10.33609/2708-129X.86.9.2020.14-27 |
| first_indexed | 2025-09-24T17:43:34Z |
| format | Article |
| fulltext |
14 ISSN 2708-129X. Укр. хім. журн., 2020
UDC 541.136. doi: 10.33609/2708-129X.86.9.2020.14-27
STRUCTURAL, SURFACE AND ELECTROCHEMICAL CHARACTERISTICS
OF TiO2 FOR LITHIUM-ION BATTERIES
N. I. Globa*, T. V. Lisnycha, Yu. V. Shmatok, V. A. Sirosh, S. A. Kirillov
Joint Department of Electrochemical Energy Systems of NAS of Ukraine, 38A Vernadsky Ave., Kyiv
03680, Ukraine
*е-mail: gnl-n@ukr.net
The paper presents structural, surface, thermodynamic and kinetic characteristics of tita-
nium dioxide samples obtained by means of alkaline hydrolysis of TiCl4 by LiOH solutions
and further heat treatment. TiO2 samples have the anatase structure with crystallite size of
7–10 nm. An increase in the heat treatment temperature from 150 °C to 470 °C leads to a de-
crease in the specific surface area from 404 to 80 m2/g and the total pore volume from 0.340
to 0.152 cm3/g. The influence of electrolyte composition and surface properties of TiO2 on its
behavior in cells with lithium anode investigated by means of galvanostatic cycling and imped-
ance spectroscopy is discussed.
Key words: titanium dioxide, surface properties, electrolyte, solid electrolyte interface, qua-
si-equilibrium voltage
INTRODUCTION. Titanium dioxide TiO2
is a well-studied electrode material for lithi-
um-ion batteries. Among known TiO2 struc-
tural modifications, titanium dioxide with ana-
tase structure is characterized by high specific
capacity and its stability during the long-term
cycling.
The process of lithium intercalation-dein-
tercalation in the structure of TiO2 proceeds
in accordance with reaction 1, which corre-
sponds to the theoretical specific capacity of
335 mAh/g (for x = 1)
TiO2 + xLi + xe− ↔ LixTiO2. (1)
However, the experimentally obtained
specific capacity, as a rule, does not exceed
200 mAh/g and corresponds to ~0.6 moles of
lithium ions reversibly intercalating into the
structure of TiO2. Higher values of discharge
capacity are realized at higher temperatures [1]
or for TiO2 nanoparticles of less than 7 nm [2].
There are also publications in the litera-
ture with comparatively higher values of spe-
cific capacity obtained by cycling of TiO2 in
cells with lithium anode. Specific capacities of
276 mAh/g at the first cycle and 218 mAh/g
upon cycling with a coulombic efficiency
of 79 % were obtained by the authors [3] for
UCJ № 9 / Vol. 86N. I. Globa, T. V. Lisnycha, Yu. V. Shmatok, V. A. Sirosh, S. A. Kirillov
15https://ucj.org.ua
electrodes consisting of mesoporous TiO2
spheres / graphene composite.
The influence of particle size, structural and
surface characteristics of TiO2 on its specific
capacity and stability cycling are studied in de-
tail [4–12]. It has been noted that a decrease in
particle size and an increase in the specific sur-
face of TiO2 improve its capacity and cycling
properties.
It is known that the discharge of TiO2 with
the formation of Li1TiO2 compound is thermo
dynamically possible [13]. However, experi-
mental specific capacities close to theoretical
values are not achieved as a result of kinetic
difficulties caused by a decrease of diffusion
coefficient of lithium at x > 0.5.
The reason of the increase in the diffusion
coefficient is the formation of Li1TiO2 that
complicates the access of lithium cations to the
surface of TiO2 particles. At the voltage value
of ~1.75 V, the discharge proceeds in the con-
ditions of simultaneous presence of two phas-
es, namely TiO2 phase and rhombic LiхTiO2
formed as a result of intercalation of lithium.
An increase in the thickness of the LiхTiO2 lay-
er leads to a change in the kinetics of interca-
lation-deintercalation of lithium, changing the
nature of discharge-charge curves that turn
into a sloping curve with a relatively small pla-
teau at the voltage of ~ 1.45 V.
In accordance with the results given in Ref.
[14], the quasi-equilibrium voltage on the dis-
charge curve at the voltage region of ~ 1.75 V
depends on the size of TiO2 particles, and their
increase from 15 nm to 300 nm leads to in-
creasing the quasi-equilibrium voltage from
1.802 V to 1.811 V. The authors explain this
effect by the difference in the surface energy of
the compounds formed upon discharge. The
surface energy of β-LiTiO2 phase is larger in
comparison with the α-LixTiO2 phase, which
leads to a higher value of the quasi-equilibrium
voltage. It is also noted that the dependence of
the values of quasi-equilibrium voltage on the
particle size may arise from capillary effects
affecting the chemical potential of crystallites.
The particle size reduction contributes to in-
creasing the chemical potential of crystallite
and thereby reduces the quasi-equilibrium
voltage of TiO2 vs. Li/Li+ [14].
In addition to dimensional effects and struc-
tural properties of TiO2, specific and kinetic
characteristics of lithium intercalation-dein-
tercalation reaction also depend on the elec-
trolyte composition. This is due to the fact that
electrical conductivity and the range of elec-
trochemical stability potentials of electrolyte
determine the resistance at the phase bounda-
ry and in the porous structure of electrode. The
effect of electrolyte composition is manifested
especially at low voltage discharge. This is due
to processes of electrolyte decomposition and
solid electrolyte film formation showing up in
this voltage region.
The purpose of this work is to determine
the effect of annealing conditions of TiO2 on its
physico-chemical parameters, thermodynamic
and kinetic characteristics in lithium cells with
different electrolyte composition.
EXPERIMENT AND DISCUSSION OF THE
RESULTS. TiO2 samples were synthesized by
means of alkaline hydrolysis of TiCl4 by LiOH
solutions. Precipitates obtained were washed
with distilled water until pH 7 was reached,
dried at 150 °C for 10 h in air, and subjected to
further thermal treatment at 350–470 °C with
total duration up to 46 h (350 °C – 4 h, 350 °C –
26 h, 350 °C – 40 h, 350 °C – 40 h + 470 °C – 6 h).
The phase composition of the samples was
studied by means of X-ray diffraction (XRD) on
PHISICAL CHEMISTRY STRUCTURAL, SURFACE AND ELECTROCHEMICAL CHARACTERISTICS OF TiO2 FOR APPLICATION IN LITHIUM-ION BATTERIES
16 ISSN 2708-129X. Укр. хім. журн., 2020
a DRON 4-07 diffractometer (LOMO, Russia)
with Cu-Kα radiation. The crystallite size was
calculated by the Scherrer equation from the
broadening of the (101) peak. The morphology
and particle size were determined by scanning
electron microscopy (SEM) on a JEOL JSM
6700F microscope (Japan). The pore size and
porosity were found by the BET method on a
Micrometrics ASAP 2000 device (USA) using
N2 adsorption-desorption isotherms at 77 K.
Electrochemical properties of the materi-
als in question were investigated in CR2016
coin cells with a lithium electrode. The work-
ing electrodes consisted of 85 % of TiO2, 10 %
of Timcal Super P carbon black and 5 % of a
poly(vinylidenedifluoride) binder (PVDF,
Solef 6020, Solvay). A dry mixture of TiO2 and
carbon black was gradually added to a solu-
tion of PVDF in N-methyl-pyrrolidone (99 %,
Aldrich) and stirred under the rotation speed
of ~2500 rpm. The resulting slurry was cast
onto the surface of 50 μm thick aluminum foil
using a doctor blade. The cathode tape was
dried at 60 °C until complete removal of the
solvent and then rolled. Finally, cathodes cut
in the form of disks with the area of 2 cm2 were
dried in vacuum at 120 °С for 6–7 h directly
before assembling the cells. The active material
load was ≈ 5,5 mg/cm2. Celgard 2400 polypro-
pylene film was used as a separator.
Electrolytes were prepared using a mixture
of ethylene carbonate (ЕC, 98%, Aldrich) and
dimethyl carbonate (DMC, 99%, Aldrich)
taken in the volume ratio of 1:1. LiClO4
(Synbias, Ukraine) was additionally recrys-
tallized and dried in vacuum at 170 °C for
14 h. LiPF6 (99.9%, Gelon) and LiN(CF3SO2)2,
(LiTFSI, 99%, Aldrich) were also dried in
vacuum before the preparation of solutions.
The lithium salt concentration in electrolyte
solution was 1 mol/L. All works on electrolyte
preparation and cell assembling were carried
out in dry glove boxes.
The electrical conductivity of the electro-
lytes was determined in the temperature range
of 15–50 °C and calculated on the basis of
impedance spectra (Z2000 impedancemeter,
Elins, Russia), obtained in the 100-1 kHz fre-
quency range in glass cells with plane-parallel
platinum electrodes.
Galvanostatic cycling was carried out at the
constant temperature of 25 ± 1 °C on a Neware
Battery Testing System (China). Charge/dis-
charge investigations were performed in the
voltage ranges of 1.5-2.75 V and 1.0-2.75 V vs.
Li/Li+ at different current densities, expressed
in C units (1 C = 335 mA/g).
Physico-chemical characterization of TiO2.
According to the XRD data (Fig. 1), all TiO2
samples have the anatase structure. In all cas-
es, no impurity peaks have been detected. The
sample dried at 150 ºC is of low crystallinity, as
indicated by weak peaks in the respective XRD
pattern. Total crystallinity increases with in-
creasing temperature and duration of heating.
The crystallite sizes d(101) calculated using the
width of the (101) reflections are presented in
Table 1. Their values change twice from 5 nm
for the dried sample to ~10 nm for the sample
treated at 470 ºC.
As can be seen from the SEM micrographs
(Fig. 2), TiO2 samples consist of highly aggre-
gated, irregularly shaped nanoparticles. The
size of the particles depends on the thermal
annealing conditions (temperature and dura-
tion) and varies in the range of ~40–80 nm.
The particle sizes exceed the crystallite sizes,
which means that each particle consists of up
to tencrystallites as the result of aggregation of
nanoscale crystallites upon heating.
UCJ № 9 / Vol. 86N. I. Globa, T. V. Lisnycha, Yu. V. Shmatok, V. A. Sirosh, S. A. Kirillov
17https://ucj.org.ua
Fig. 1 XRD patterns of TiO2 samples
According to the IUPAC classification, ni-
trogen adsorption-desorption isotherms for
the samples can be attributed to type IV iso-
therms with capillary condensation in mes-
opores. The calculated values of the specific
surface area (Ssp) and total pore volume (Vp) of
TiO2 samples greatly depend on the treatment
conditions (Table 1). After drying at 150 °C,
the specific surface area is 404 m2/g and the
pore volume is 0.34 cm3/g. Heat treatment at
temperatures up to 470 °C leads to a decrease
in the specific surface area and the pore vol-
ume to 80 m2/g and 0.152 cm3/g, respectively.
At the same time, the pore size increases from
1.7 to 2.75 nm.
Table 1.
Crystallite size and surface properties
of TiO2 samples
Sample d(101),
nm
Ssp,
m2/g
Vp,
cm3/g
Rp,
nm
150 ºC – 10 h 5.0 404 0.340 1.7
350 ºC – 4 h 7.0 174 0.264 2.2
350 ºC – 26 h 8.5 125 0.230 2.65
350 ºC – 40 h 8.8 113 0.225 2.7
470 ºC – 6 h 9.8 80 0.152 2.75
Fig. 2 SEM micrographs of TiO2 powders thermally treated at150 ºC (a), 350 ºC – 4h (b), 350 ºC – 26h
(c), 350 ºC – 40h (d), 470 ºC – 6h (e)
PHISICAL CHEMISTRY STRUCTURAL, SURFACE AND ELECTROCHEMICAL CHARACTERISTICS OF TiO2 FOR APPLICATION IN LITHIUM-ION BATTERIES
18 ISSN 2708-129X. Укр. хім. журн., 2020
Effect of electrolyte composition on electro-
chemical properties of TiO2. Electrochemical
investigations were made for TiO2 samples
thermally treated at 350 ºC and 470 ºC. The
compositions of electrolytes and their specific
conductivities are presented in Table 2.
In the first discharge cycles, process of lith-
ium intercalation into the TiO2 structure are
complicated by the electrolyte decomposition
and formation of a solid electrolyte interface
(SEI). The contribution of side (secondary)
reactions depends on the electrolyte composi-
tion, cycling voltage range, as well as the sur-
face and structural properties of the electrodes.
The quantitative contribution of the side pro-
cesses to the overall electrochemical process
can be determined based on the ratio of the
discharge and charge capacities of the first two
cycles. The results given in Table 3 demon-
strate how the electrolyte composition and the
conditions of thermal annealing of TiO2 affect
the ratio of the discharge capacities of the first
(Q1) and second (Q2) cycles. The Q1/Q2 ratio
in the case of 1M LiClO4 – EC:DMC electro-
lyte decreases with an increase in temperature
and time of annealing of TiO2. The maximum
value of Q1/Q2 is characteristic of the sam-
ple 350-4. At the same time, the Q1/Q2 ratios
obtained with the 1M LiPF6 – EC:DMC and
1M LiTFSI – EC:DMC electrolytes are signifi-
cantly lower and practically independent of the
heat treatment conditions of TiO2.
Table 2
Composition and conductivity of electrolytes
No Electrolyte composition
Specific conductivity, mSm/сm
15 °С 25 °С 40 °С 50 °С
1 1M LiPF6 – EC:DMC 9.8 12.1 15.4 17.5
2 1M LiClO4 – EC:DMC 7.7 9.4 12.0 13.6
3 1M LiTFSI – EC:DMC 7.5 9.2 11.7 13.5
Table 3.
Effect of electrolyte composition and thermal annealing conditions
on the specific capacity of the first and second cycle
Sample Electrolyte composition Q1, mAh/g Q2, mAh/g Q1/Q2
At cycling voltage range of 2.75–1.5 V
350 ºC – 4 h 1M LiClO4 – EC:DMC 186 109 1.7
470 ºC – 6 h 1M LiClO4 – EC:DMC 163 144 1.13
350 ºC – 4 h 1M LiPF6 – EC:DMC 172 163 1.05
350 ºC – 4 h 1M LiTFSI – EC:DMC 160 150 1.07
At cycling voltage range of 2.75–1.0 V
350 ºC – 4 h 1M LiClO4 – EC:DMC 290 206 1.41
350 ºC – 4 h 1M LiPF6 – EC:DMC 266 224 1.19
470 ºC – 6 h 1M LiPF6 – EC:DMC 246 219 1.12
UCJ № 9 / Vol. 86N. I. Globa, T. V. Lisnycha, Yu. V. Shmatok, V. A. Sirosh, S. A. Kirillov
19https://ucj.org.ua
The charge-discharge curves of the 10th cycle
registered in different electrolytes are shown in
Fig. 3. The points on the curves correspond-
ing to quasi-equilibrium voltage obtained after
2 hours of relaxation, represent open circuit
voltage (OCV). The curves have three main
parts corresponding to different stages of lithi-
um intercalation [5, 8, 15, 16].
The first part of the discharge curve (before
a plateau at ~1.75 V) is associated with the for-
mation of SEI. It is assumed that in this voltage
range, there is no formation of new phases and
the x value in LiхTiO2 compound is less than
0.028 [14]. In accordance with our results, the
value of x does not exceed 0.03.
The plateau on the discharge curve at the
voltage of ~1.75 V corresponds to the forma-
tion of a LiхTiO2 compound (where х < 0.5)
with the theoretical specific capacity of
167.5 mAh/g. However, practically, the value
of x depends on the morphology and struc-
tural characteristics of TiO2 particles and, as
a rule, does not exceed ~0.4 [14]. The authors
[14] suggest that the discharge in this volt-
age region is determined by the simultane-
ous presence of the initial TiO2 phase and an
orthorhombic LiхTiO2 phase formed during
discharge. The process limiting the kinetics
of the discharge is associated with the limited
access of lithium ions to the surface of TiO2
as a result of formation of LixTiO2 structure.
Therefore, a decrease in the particle size of
TiO2 is considered as the main factor con-
tributing to an increase in the specific capac-
ity. That is, the smaller the particle sizes, the
higher the specific capacity of TiO2. It is be-
lieved that when the LiхTiO2 layer thickness
is more than 3-4 nm, the discharge rate is sig-
nificantly inhibited and the specific capacity
decreases [14].
Fig. 3 Discharge-charge curves of the 10th
cycle for Li-TiO2 cells with different electrolytes
at the current density of 40 mA/g (TiO2 sample
350 ºC – 4 h)
The discharge in the 1.7-1.0 V voltage range
is associated with filling of remaining octahe-
dral sites and formation of the LixTiO2 (x>0,5)
compound [17]. At the voltage below 1.7 V,
the discharge curve represents a sloping curve
without pronounced voltage plateau. The spe-
cific capacity value of TiO2 in this region is
determined by both structural and surface fac-
tors (crystallite size and specific surface) and
the properties of the SEI formed. The first two
factors depend on the conditions of the syn-
thesis of TiO2 and the third is determined not
only by the surface and structural properties of
TiO2, but also by the properties of the electro-
lyte [14, 18-21].
PHISICAL CHEMISTRY STRUCTURAL, SURFACE AND ELECTROCHEMICAL CHARACTERISTICS OF TiO2 FOR APPLICATION IN LITHIUM-ION BATTERIES
20 ISSN 2708-129X. Укр. хім. журн., 2020
Fig. 4. Cycling performance of 350–4 TiO2 sam-
ple with the different electrolyte solutions in the
voltage ranges of 1.5–2.75 V (a) and 1.0-2.75 V (b)
and the effect of the discharge current density on
the specific capacity in the cycling voltage range of
1.5–2.75 V (с).
The hysteresis existing between the corre-
sponding charge and discharge curves slight-
ly depends on the electrolyte composition. In
all cases, when the concentration of lithium
ions in LiхTiO2 increases from ~0.36 to ~0.6,
the magnitude of hysteresis also increases.
Depending on the electrolyte composition, the
difference in the values of quasi-equilibrium
voltage in the lithium concentration range of
0.03–0.36 is no more than 6 mV.
The 350–4 TiO2 samples have higher sen-
sitivity to the LiClO4-containing electrolyte
manifesting a significant decrease of the spe-
cific capacity at the second cycle in comparison
with the first cycle, even at the relatively low
current density (40 mA/g), Table 3.
The decrease in capacity is due to a signifi-
cant increase in cell internal resistance, which
was determined by software for cycling, ac-
cording to the voltage drop when the discharge
current was turned on. So, on cycling in the
voltage range of 1.5–2.75 V, the cell resistance
values at the first and second cycles for dif-
ferent samples changed from 178 to 293 Ohm
for 350–4 sample, from 150 to 216 Ohm for
350–26 sample, from 150 to 208 Ohm for
350–40 sample and from 95 to 131 Ohm for
470–6 sample. After approximately 5–6 cy-
cles, the cell resistance decreases up to 120–
140 Ohm and is very close for all the stud-
ied samples. As a result, the specific capacity
increases and remains stable during further
cycling. Similar results have been published
previously by two of us [12].
In more detail, the effect of the electrolyte
composition on the change of specific capacity
from the cycle number and current density is
shown in Fig. 4. In the cycling voltages range
of1.5–2.75 V (Fig. 4a), the specific capacity re-
mains stable for all electrolyte compositions.
However, when the discharge voltage decreas-
es to 1.0 V, the specific capacity decreases no-
ticeably faster in the case of LiClO4-containing
electrolyte (Fig. 4b). The dependence of the
UCJ № 9 / Vol. 86N. I. Globa, T. V. Lisnycha, Yu. V. Shmatok, V. A. Sirosh, S. A. Kirillov
21https://ucj.org.ua
specific capacity on the discharge current den-
sity is shown in Fig. 4c. The minimum capacity
loss with a change of current density from 40 to
400 mA/g is obtained in 1M LiPF6 – EC:DMC
whose specific conductivity is the highest
(Table 2).
Quasi-equilibrium voltage and kinetic
characteristics of TiO2. Fig. 5 shows the dis-
charge-charge curves and the values of the
quasi-equilibrium voltage obtained for 350–4
and 470–6 samples in different electrolytes.
These curves do not differ from those dis-
cussed previously (Fig. 2). However, the speci-
ficcapacity of 470–6 sample obtained on the
voltage plateau of 1.75 V is approximately 10%
higher than that of the sample 350–4, and the
difference in the values of quasi-equilibrium
voltages is not more than 6 mV.
Fig. 5. Discharge-charge curves of 350-4 and 470-6 TiO2 samples at the current density of 40 mA/g in
electrolytes (a) 1M LiPF6 – EC:DMC and (b) 1M LiClO4 – EC:DMC. Points indicate quasi-equilibrium
voltage values.
Fig. 6 shows the dependences of specific ca-
pacity of TiO2 on cycle number and discharge
current density obtained in 1М LiClO4–
EC:DMC electrolyte upon cycling in different
voltage ranges. The specific capacity during cy-
cling in the voltage range of 2.75–1.5 V is quite
stable for all TiO2 samples. When the discharge
voltage decreases to 1.0 V, the specific capaci-
ty of the 350-4 sample decreases more signifi-
cantly (Fig. 6 с).
When samples are cycled within a volt-
age range of 1–2.75 V at the current density of
40 mA/g, the specific capacity is practically in-
dependent of the conditions of thermal anneal-
ing of TiO2 (Fig. 7a). However, at current den-
sity of 400 mA/g, the specific capacity of 350–4
PHISICAL CHEMISTRY STRUCTURAL, SURFACE AND ELECTROCHEMICAL CHARACTERISTICS OF TiO2 FOR APPLICATION IN LITHIUM-ION BATTERIES
22 ISSN 2708-129X. Укр. хім. журн., 2020
and 470–6 samples decreases by 50 and 25 %,
respectively. We suppose that this may be due
to the difference in the resistance of SEI, whose
properties affect the charge transfer resistance.
Fig. 6. Dependences of specific capacity of dif-
ferent TiO2 samples on the cycle number (a) and
discharge current density (b) during the cycling in
the voltage range of 1.5–2.75 V and (c) on the cycle
number during the cycling in the voltage range of
1.0–2.75 V. Electrolyte – 1М LiClO4 – EC:DMC
Impedance spectroscopy of Li-TiO2 cells. In
order to determine a relationship between
the thermal annealing conditions of TiO2 and
the resistance occurring in Li-TiO2 cells, we
have analyzed the impedance spectra obtained
at the resistance occurring in Li-TiO2 cells, we
have analyzed the impedance spectra obtained
at the various stages of discharge. To this end,
TiO2 samples have been taken with maximum
and minimum specific surface area, 350–4 and
470–6, respectively. Fig. 8 shows the impedance
hodographs in the Nyquist coordinates ob-
tained at the various stages of discharge of Li-
TiO2 cells with 1M LiPF6 – EC:DMC electrolyte.
The impedance spectra for almost all discharge
stages consist of two incomplete semicircles at
high and medium frequencies and an almost
straight line at low-frequencies. The presence of
two semicircles in the high-frequency region in-
dicates the formation of inhomogeneous layers
with different conductivities or diffusion rates.
The radii of semicircles, which are responsible
for the resistance of the real and imaginary parts
of the impedance for samples 350–4 and 470–6
are significantly different.
The resistance Rmin is basically equal to the
sum of the resistances of the electrolyte layer,
separator and the interface between the po-
rous electrode and current collector. The Rmin
value obtained for two samples do not differ
significantly and are practically constant over
the whole discharge process. The authors [22]
believe that the semicircle obtained in the
high-frequency region corresponds to a par-
allel combination of resistance and capacity
of the SEI and determine the migration rate of
lithium ions in its surface layer. Thus, it can be
assumed that the difference in the resistance of
the semicircles in the high-frequency region
may be ascribed to differences in the structure
of the SEI whose properties depend on the sur-
face properties of the samples.
UCJ № 9 / Vol. 86N. I. Globa, T. V. Lisnycha, Yu. V. Shmatok, V. A. Sirosh, S. A. Kirillov
23https://ucj.org.ua
Fig. 7. Dependences of specific capacity of different TiO2 samples on the cycle number (a) and dis-
charge current density (b) during the cycling in the voltage range of 1.0-2.75 V. Electrolyte – 1M LiPF6 –
EC:DMC.
Fig. 8 Impedance spectra of Li-TiO2 cells at the various stages of discharge with TiO2 samples 350–4
(a) and 470–6 (b). Electrolyte – 1M LiPF6 – EС:DMС.
The dependence of the resistance of the ac-
tive part of impedance and OCV on the state
of discharge is shown in Fig. 9. The resistance
values were determined at the frequency of 0.1
Hz. The greatest difference of the resistance
obtained for fully charged cells (Qdch = 0) and
in a case of 350–4 sample its value is about
5 times higher than for 470–6 sample, where-
PHISICAL CHEMISTRY STRUCTURAL, SURFACE AND ELECTROCHEMICAL CHARACTERISTICS OF TiO2 FOR APPLICATION IN LITHIUM-ION BATTERIES
24 ISSN 2708-129X. Укр. хім. журн., 2020
in the OCV values practically do not differ.
However, after discharge to the capacity of 40
mAh/g, the resistance of both cells decreases
and then does not change significantly within
the discharge plate of 1.75 V. The closest both
in character and resistance are the spectra ob-
tained after the formation of LixTiO2 (x>0.5),
suggesting that the diffusion rate at the end of
the discharge is determined by the conductivi-
ty of LixTiO2 phase.
Fig. 9. Dependences of the resistance of the ac-
tive part of impedance and OCV at different stages
of discharge
CONCLUSIONS. In this paper, results of the
investigation of structural, surface, thermody-
namic and kinetic characteristics of titanium
dioxide obtained by alkaline hydrolysis are
presented. According to XRD and SEM data,
TiO2 samples have the anatase structure and
consist of highly aggregated, irregularly shaped
nanoparticles of 40–80 nm. The specific sur-
face area of the dried TiO2 sample is 404 m2/g
and farther heat treatment at 350–470 °C with
different duration leads to a gradual decrease
in the specific surface area to 80 m2/g.
The thermodynamics and kinetics of lith-
ium intercalation-deintercalation process in
TiO2 have been studied in a wide range of
current densities at different cycling voltage
conditions. The specific capacity and its sta-
bility upon cycling at different current loads
depend on the electrolyte composition and
thermal annealing conditions of TiO2 sam-
ples. It is shown that at low current densities,
the structural and surface properties almost
do not affect the specific capacity of TiO2.
The maximum specific capacity upon cycling
in the voltage range of 1.0–2.75 V and at the
current density of 40 mA/g obtained in 1M
LiPF6 – EC:DMC electrolyte is ~ 210 mAh/g
for both 350–4 and 470–6 TiO2 samples, while
the decrease in capacity after 100 cycles is ~
18%. The kinetics of the discharge process
at high current densities is limited by charge
transfer in the solid electrolyte interface,
whose resistance depends on the specific sur-
face area of TiO2. A decrease in the specific
surface of TiO2 promotes the decrease in the
charge transfer resistance and results in the
increase in specific capacity. At the current
density of 400 mA/g, the specific capacities
of 145 mAh/g and 80 mAh/g are obtained
for TiO2 samples with the specific surface of
80 m2/g (sample 470–6) and 175 m2/g (sample
350–4), respectively.
Acknowledgement. The authors are grate-
ful to National Academy of Sciences of Ukraine
for financial and technical support of research.
UCJ № 9 / Vol. 86N. I. Globa, T. V. Lisnycha, Yu. V. Shmatok, V. A. Sirosh, S. A. Kirillov
25https://ucj.org.ua
СТРУКТУРНІ, ПОВЕРХНЕВІ
ТА ЕЛЕКТРОХІМІЧНІ ХАРАКТЕРИСТИКИ
TiO2 ДЛЯ ВИКОРИСТАННЯ В ЛІТІЙ-ІОННИХ
АКУМУЛЯТОРАХ
Н. І. Глоба*, Т. В. Ліснича, Ю. В. Шматок,
В. А. Сірош, С. О. Кириллов
Міжвідомче відділення електрохіміч-
ної енергетики НАН України, бульвар
Академіка Вернадського, 38а, Київ 03680,
Україна
*е-mail: gnl-n@ukr.net
У роботі подано результати дослідження
структурних, поверхневих, термодинаміч-
них та кінетичних характеристик зразків
діоксиду титану, отриманих методом луж-
ного гідролізу з розчинів TiCl4 і LiOH із на-
ступним термообробленням за різних умов.
Показано, що зразки ТіО2 мають структуру
анатазу з розмірами кристалітів 5–10 нм.
Підвищення температури термооброблен-
ня зі 150 °C до 470 °C призводить до змен-
шення питомої площі поверхні ТіО2 з 404
до 80 м2/г та загального об’єму пор з 0,340
до 0,152 см3/г. Методами гальваностатично-
го циклування та імпедансної спектроско-
пії досліджено вплив складу електроліту
та поверхневих властивостей зразків ТіО2
на їхні питомі, термодинамічні та кінетич-
ні характеристики в комірках з літієвим
анодом.
Ключові слова: діоксид титану, питома
поверхня, електроліт, твердоелектролітна
плівка, квазі-рівноважний потенціал.
СТРУКТУРНЫЕ, ПОВЕРХНОСТНЫЕ
И ЭЛЕКТРОХИМИЧЕСКИЕ ХАРАКТЕРИСТИКИ
TiO2 ДЛЯ ИСПОЛЬЗОВАНИЯ В ЛИТИЙ-
ИОННЫХ АККУМУЛЯТОРАХ
Н. И. Глоба*, Т. В. Лесничая, Ю. В. Шматок,
В. А. Сирош, С. А. Кириллов
Межведомственное отделение электро-
химической энергетики НАН Украины, буль
вар Академика Вернадского, 38а, Киев 03680,
Украина
*е-mail: gnl-n@ukr.net
В работе представлены результаты ис-
следования структурных, поверхностных,
термодинамических и кинетических ха-
рактеристик образцов диоксида титана,
полученных методом щелочного гидролиза
из растворов TiCl4 и LiOH с последующей
термообработкой при разных условиях.
Показано, что образцы ТіО2 имеют струк-
туру анатаза с размерами кристаллитов
5–10 нм. Повышение температуры термо-
обработки со 150 °C до 470 °C приводит к
уменьшению удельной площади поверхно-
сти ТіО2 со 404 до 80 м2/г и общего объема
пор с 0,340 до 0,152 см3/г. Методом гальва-
ностатического циклирования и импеданс-
ной спектроскопии исследовано влияние
состава электролита и поверхностных
свойств образцов ТіО2 на их удельные,
термодинамические и кинетические харак-
теристики в ячейках с литиевым анодом.
Ключевые слова: диоксид титана, удель-
ная поверхность, электролит, твердоэлект
ролитная пленка, квази-равновесный по-
тенциал.
PHISICAL CHEMISTRY STRUCTURAL, SURFACE AND ELECTROCHEMICAL CHARACTERISTICS OF TiO2 FOR APPLICATION IN LITHIUM-ION BATTERIES
26 ISSN 2708-129X. Укр. хім. журн., 2020
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27https://ucj.org.ua
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Стаття надійшла 30.09.2020.
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| id | oai:ojs2.1444248.nisspano.web.hosting-test.net:article-231 |
| institution | Ukrainian Chemistry Journal |
| keywords_txt_mv | keywords |
| language | English |
| last_indexed | 2026-07-23T01:04:57Z |
| publishDate | 2020 |
| publisher | V.I.Vernadsky Institute of General and Inorganic Chemistry |
| record_format | ojs |
| resource_txt_mv | ucjorgua/3b/a693d5c4dc078c0ef0ac65dc25277e3b.pdf |
| spelling | oai:ojs2.1444248.nisspano.web.hosting-test.net:article-2312026-07-22T08:23:44Z STRUCTURAL, SURFACE AND ELECTROCHEMICAL CHARACTERISTICS OF TiO2 FOR LITHIUM-ION BATTERIES СТРУКТУРНЫЕ, ПОВЕРХНОСТНЫЕ И ЭЛЕКТРОХИМИЧЕСКИЕ ХАРАКТЕРИСТИКИ TiO2 ДЛЯ ИСПОЛЬЗОВАНИЯ В ЛИТИЙ- ИОННЫХ АККУМУЛЯТОРАХ СТРУКТУРНІ, ПОВЕРХНЕВІ ТА ЕЛЕКТРОХІМІЧНІ ХАРАКТЕРИСТИКИ TiO2 ДЛЯ ВИКОРИСТАННЯ В ЛІТІЙ-ІОННИХ АКУМУЛЯТОРАХ Globa, Nataliy Lisnycha, Tatyana Shmatok, Yurii Sirosh, Vitalii Kirillov, Sviatoslav titanium dioxide, surface properties, electrolyte, solid electrolyte interface, quasi-equilibrium voltage The paper presents structural, surface, thermodynamic and kinetic characteristics of titanium dioxide samples obtained by means of alkaline hydrolysis of TiCl4 by LiOH solutions and further heat treatment. TiO2 samples have the anatase structure with crystallite size of 7–10&nbsp;nm. An increase in the heat treatment temperature from 150 °C to 470 °C leads to a decrease in the specific surface area from 404 to 80 m2/g and the total pore volume from 0.340 to 0.152 cm3/g. The influence of electrolyte composition and surface properties of TiO2 on its behavior in cells with lithium anode investigated by means of galvanostatic cycling and impedance spectroscopy is discussed. V.I.Vernadsky Institute of General and Inorganic Chemistry 2020-10-20 Article Article Physical chemistry Физическая xимия Фізична xімія application/pdf https://ucj.org.ua/index.php/journal/article/view/231 10.33609/2708-129X.86.9.2020.14-27 Ukrainian Chemistry Journal; Vol. 86 No. 9 (2020): Ukrainian Chemistry Journal; 14-27 Украинский химический журнал; ##issue.vol## 86 ##issue.no## 9 (2020): Украинский химический журнал; 14-27 Український хімічний журнал; Том 86 № 9 (2020): Український хімічний журнал; 14-27 2708-129X 2708-1281 en https://ucj.org.ua/index.php/journal/article/view/231/125 Copyright (c) 2020 Nataliy Globa, Tatyana Lisnycha, Yurii Shmatok, Vitalii Sirosh, Sviatoslav Kirillov https://creativecommons.org/licenses/by-nc/4.0 |
| spellingShingle | Globa, Nataliy Lisnycha, Tatyana Shmatok, Yurii Sirosh, Vitalii Kirillov, Sviatoslav СТРУКТУРНІ, ПОВЕРХНЕВІ ТА ЕЛЕКТРОХІМІЧНІ ХАРАКТЕРИСТИКИ TiO2 ДЛЯ ВИКОРИСТАННЯ В ЛІТІЙ-ІОННИХ АКУМУЛЯТОРАХ |
| title | СТРУКТУРНІ, ПОВЕРХНЕВІ ТА ЕЛЕКТРОХІМІЧНІ ХАРАКТЕРИСТИКИ TiO2 ДЛЯ ВИКОРИСТАННЯ В ЛІТІЙ-ІОННИХ АКУМУЛЯТОРАХ |
| title_alt | STRUCTURAL, SURFACE AND ELECTROCHEMICAL CHARACTERISTICS OF TiO2 FOR LITHIUM-ION BATTERIES СТРУКТУРНЫЕ, ПОВЕРХНОСТНЫЕ И ЭЛЕКТРОХИМИЧЕСКИЕ ХАРАКТЕРИСТИКИ TiO2 ДЛЯ ИСПОЛЬЗОВАНИЯ В ЛИТИЙ- ИОННЫХ АККУМУЛЯТОРАХ |
| title_full | СТРУКТУРНІ, ПОВЕРХНЕВІ ТА ЕЛЕКТРОХІМІЧНІ ХАРАКТЕРИСТИКИ TiO2 ДЛЯ ВИКОРИСТАННЯ В ЛІТІЙ-ІОННИХ АКУМУЛЯТОРАХ |
| title_fullStr | СТРУКТУРНІ, ПОВЕРХНЕВІ ТА ЕЛЕКТРОХІМІЧНІ ХАРАКТЕРИСТИКИ TiO2 ДЛЯ ВИКОРИСТАННЯ В ЛІТІЙ-ІОННИХ АКУМУЛЯТОРАХ |
| title_full_unstemmed | СТРУКТУРНІ, ПОВЕРХНЕВІ ТА ЕЛЕКТРОХІМІЧНІ ХАРАКТЕРИСТИКИ TiO2 ДЛЯ ВИКОРИСТАННЯ В ЛІТІЙ-ІОННИХ АКУМУЛЯТОРАХ |
| title_short | СТРУКТУРНІ, ПОВЕРХНЕВІ ТА ЕЛЕКТРОХІМІЧНІ ХАРАКТЕРИСТИКИ TiO2 ДЛЯ ВИКОРИСТАННЯ В ЛІТІЙ-ІОННИХ АКУМУЛЯТОРАХ |
| title_sort | структурні, поверхневі та електрохімічні характеристики tio2 для використання в літій-іонних акумуляторах |
| topic_facet | titanium dioxide surface properties electrolyte solid electrolyte interface quasi-equilibrium voltage |
| url | https://ucj.org.ua/index.php/journal/article/view/231 |
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