ELECTROCHEMICAL PROPERTIES OF THE ALUMINIUM FILMS WITH GRAPHENE-BENTONITE COVERING
The changes in the conductivity type, capacitance value, and equivalent circuit models of the composite materials, taking into account the impact of graphene-bentonite covers on the aluminum carrier, are discussed. The EIS spectra of the pure aluminum foil lay in the positive reactive resistance dom...
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| Дата: | 2024 |
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V.I.Vernadsky Institute of General and Inorganic Chemistry
2024
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Ukrainian Chemistry Journal| _version_ | 1871466048805404672 |
|---|---|
| author | Boichuk, Oleksandr Pershina, Katherine |
| author_facet | Boichuk, Oleksandr Pershina, Katherine |
| author_institution_txt_mv | [
{
"author": "Oleksandr Boichuk",
"institution": "Vernadsky Institute of General and Inorganic Chemistry N.A.S of Ukraine, Kiev, Palladin av., 32\/34,03142 Ukraine"
},
{
"author": "Katherine Pershina",
"institution": "Vernadsky Institute of General and Inorganic Chemistry N.A.S of Ukraine, Kiev, Palladin av., 32\/34,03142 Ukraine"
}
] |
| author_sort | Boichuk, Oleksandr |
| baseUrl_str | https://ucj.org.ua/index.php/journal/oai |
| collection | OJS |
| datestamp_date | 2026-07-22T08:23:54Z |
| description | The changes in the conductivity type, capacitance value, and equivalent circuit models of the composite materials, taking into account the impact of graphene-bentonite covers on the aluminum carrier, are discussed. The EIS spectra of the pure aluminum foil lay in the positive reactive resistance domain characterized by the impact of the inductance. The conductivity value is 3.9± 0.1 Sm/cm with decreasing electrostatic capacitance from 0.08 to 0.02 F/g in the frequency range 10-1÷104 Hz. Applying the graphene-bentonite coating changes types of conductivity, from electron type to ionic type. Conductivity has two orders smaller value, and rises with increasing the frequency from 0.014 to 0.02 Sm/cm. The electrochemical equivalent circuit in the case of covering by graphene-bentonite mixtures is the R-CPE parallel circuit has characteristic of the porous electrodes in a supercapacitor. Presence of a dielectric component (bentonite) on the foil surface limits the polarization of composite material and decreases the capacitance value. |
| doi_str_mv | 10.33609/2708-129X.90.5.2024.21-27 |
| first_indexed | 2025-09-24T17:43:56Z |
| format | Article |
| fulltext |
21
UDC 544.023+549.02+553.08+547.99 doi: 10.33609/2708-129X.90.5.2024.21-27
ELECTROCHEMICAL PROPERTIES OF THE ALUMINIUM FILMS
WITH GRAPHENE-BENTONITE COVERING.
O.V. Boychuk1*, K. D. Pershina2
1V.I. Vernadskiy Institute of General and Inorganic Chemistry N.A.S. of Ukraine,
32/34 Acad. Palladin ave., 03142 Kyiv, Ukraine;
2Joint Department of the Electrochemical Energy Systems N.A.S. of Ukraine,
38 А Acad. Vernadskiy ave., 03680 Kyiv, Ukraine
Email: 9spiritlucker9@gmail.com
The changes in the conductivity type, capacitance value, and equivalent circuit models of
the composite materials, taking into account the impact of graphene-bentonite covers on the
aluminum carrier, are discussed. The EIS spectra of the pure aluminum foil lay in the positive
reactive resistance domain characterized by the impact of the inductance. The conductivity
value is 3.9± 0.1 Sm/cm with decreasing electrostatic capacitance from 0.08 to 0.02 F/g in
the frequency range 10-1÷104 Hz. Applying the graphene-bentonite coating changes types
of conductivity, from electron type to ionic type. Conductivity has two orders smaller value,
and rises with increasing the frequency from 0.014 to 0.02 Sm/cm. The electrochemical equi
valent circuit in the case of covering by graphene-bentonite mixtures is the R-CPE parallel
circuit has characteristic of the porous electrodes in a supercapacitor. Presence of a dielectric
component (bentonite) on the foil surface limits the polarization of composite material and
decreases the capacitance value.
Keywords: graphene, bentonite, aluminium foil, composite material, conductivity, ca
pacity.
INTRODUCTION. Graphene shows many
interesting optical, electronic, and mechani-
cal properties because of its two-dimension-
al (2D) crystal structure. The high speed of
charge moving in graphene with a 2D crystal
lattice is the base of the high conductivity [1].
That is why, graphene has interesting electrical
properties that can be use in modern energy
conversion devices.
Nowadays, the main requirements for bat-
teries and supercapacitors are long lifetime and
fast charging rate during recharging. Superca-
pacitors incorporated inside the batteries are
used to comply with high speed charging rates
of the device. The properties of supercapaci-
tors are low maintenance, low self-discharging,
rising power capabilities, a charge-discharge
process occurring in seconds, and long cyclic
22 ISSN 2708-129X. Укр. хім. журн., 2024
ELECTROCHEMICAL PROPERTIES OF THE ALUMINIUM FILMS WITH GRAPHENE-BENTONITE COVERING.PHISICAL CHEMISTRY
life [2]. Also, supercapacitors come out with
a higher energy density compared to conven-
tional capacitors. Electrodes of the supercapa
citor are made of porous carbon, but not long
ago, researchers started to investigate using
graphene in elements of electrodes as covering
on the aluminum conductive carrier [2].
On the other hand, aluminum is widely
used in electrical power distribution systems,
thanks to its advantages such as low density,
high conductivity, and in expensive cost [3].
The rising of it selectrical capacitance and safe-
ty of start conductivity would generate great-
er economic benefits because of reduced line
electrical losses in large power grids.
The active chemical property of aluminum
makes it difficult to upgrade it selectrical con-
ductivity by refinement and purification [4].
Furthermore, alloying is necessary for most of
aluminum’s practical applications to enhance
its mechanical strength, but alloying is detri-
mental to high electrical conductivity because
of more electron scattering centers [5, 6]. Thus,
achieving electrical conductivity at a level of
pure aluminum in practical applications is
a major challenge. One of the main ways to
solve this problem is the use of variouscovers,
especially covers consisting of 2D structures
and 3D structures such as graphene-bentonite
mixtures [7, 8].
The target of this work is to detect the effect
of a graphene-bentonite mixture on the elec-
trical properties of the conductive aluminum
foil carrier.
EXPERIMENT AND DISCUSSION OF THE
RESULTS. Natural bentonite from Dashukiv,
Ukraine was used as the main 3D matrix of the
composite for covering (Table 1).
Table 1.
The main physical and chemical proper-
ties of the bentonite.
Compound,
mass % Structure Surface area,
m2/g
SiO2 – 58.3;
А12О3 – 12.8;
Fe2O3 – 6.8;
СаО – 1.45;
MgO – 1.6;
Na2O+К2О – 0.5
Layered
Grain size
50–110 nm
36±2
Graphene C-750 (Sigma–Aldrich) with a
molecular weight of 12.01 a.u. was used as an
electroconductive component of the compo
site. Such kind of graphene has a platelet shape
and is composed of short stacks of graphene
sheets with a size of 20–50 nm. For prelimi-
nary preparation, graphene was treated with
95% ethanol to remove absorbed water from
the volume before mixturing.
The covering mixture for the aluminum car-
rier consisted of 45% natural bentonite, 45%
graphene as a conductive component, and 10%
polyvinylidene fluoride (PVDF) binder Solef
6020 (Solvay, Belgium). Covers were prepared
using slurry technology. For this the compo-
nents of the mixture in the calculated quanti-
ties were added in portions to a previously pre-
pared 7% solution of the binder in dimethy-
lacetamide, and homogenized on a high-speed
mixer at a stirring speed of 2500–3000 rpm for
40 minutes.
After that, the suspension was subjected
to ultra sonic dispersion for a total duration
of 5 min. Next, the finished suspension was
applied using a Doctor Blade applicator to a
7–8 µkm thick aluminum foil tape (current
collector). The coated foil was dried at a tem-
perature of 60–70 °C for 1 hour, rolled on ro
23https://ucj.org.ua
O.V. Boychuk, K. D. Pershina UCJ № 5 / Vol. 90
llers, compacted by 25–30%, and cut into strips
measuring 100 mm by 22 mm.
The impedance spectra of the samples were
recorded in a two-electrode cell (Fig.1) on an
Autolab 30 PGSTAT301N MetrohmAutolab
electrochemical module in a two-electrode cell
equipped with a FRA (Frequency Response
Analyzer) module in the frequency range
10-2–106 Hz. The results were processed using
Nova 2.1 and ZView2 software.
The impedance spectra of aluminum foil
and foil with graphene-bentonite coating have
significant differences in the form of impe
dance spectra and their electrochemical equi
valent circuits (Fig. 2, 3, 6). The EIS spectra
of the pure aluminum foil lay in the positive
range of reactive resistance characterized by
the impact of the inductance.
The impedance spectra of aluminum foil and foil with graphene-bentonite coating have significant
differences in the form of impedance spectra and their electrochemical equivalent circuits (Fig. 2, 3,
6). The EIS spectra of the pure aluminum foil lay in the positive range of reactive resistance
characterized by the impact of the inductance.
a
b
Fig. 2. Impedance spectra of Al foil (a), Al foil covered by graphene-bentonite mixture (b).
The electrochemical equivalent circuit of this sample is close to the equivalent circuit of the
oscillatory circuit. The main difference in these circuits is changing the capacitance (C) element onto
the constant phase element (CPE) element (Fig. 4, Table 2).
Fig. 3. Equivalent circuits of Al foil.
Table 2.
Calculations of equivalent circuits of Al foil
Element Freedo
m Value Error Error
%
R3 Free() 0.2601 0.0009 0.35
CPE1-T Free(+) 1.7 E5 62841 37.62
CPE1-P Free() -0.760 0.043 5.633
L1 Free() 2.11E-7 3.3E-8 15.764
Weighted Sum of Squares: 6.3843
Al
Z', Ohm
0,2 0,3 0,4 0,5 0,6 0,7
Z"
,
O
hm
0,0
0,5
1,0
1,5
bent_steklo(3)
Z', Ohm
35 40 45 50 55 60 65 70 75
Z"
,
O
hm
-12
-10
-8
-6
-4
-2
0
2
R3 CPE1 L1
Element Freedom Value Error Error %
R3 Free(±) 0.25702 0.00089849 0.34958
CPE1-T Free(+) 1.6704E5 62841 37.62
CPE1-P Free(±) -0.76007 0.042815 5.633
L1 Free(±) 2.1095E-7 3.3255E-8 15.764
Chi-Squared: 0.10297
Weighted Sum of Squares: 6.3843
Data File: G:\звіт\Конференция\Al.dfr
Circuit Model File: G:\звіт\БРНО\B.mdl
Mode: Run Fitting / Freq. Range (0.01 - 1000000)
Maximum Iterations: 100
Optimization Iterations: 0
Type of Fitting: Complex
Type of Weighting: Calc-Modulus
The impedance spectra of aluminum foil and foil with graphene-bentonite coating have significant
differences in the form of impedance spectra and their electrochemical equivalent circuits (Fig. 2, 3,
6). The EIS spectra of the pure aluminum foil lay in the positive range of reactive resistance
characterized by the impact of the inductance.
a
b
Fig. 2. Impedance spectra of Al foil (a), Al foil covered by graphene-bentonite mixture (b).
The electrochemical equivalent circuit of this sample is close to the equivalent circuit of the
oscillatory circuit. The main difference in these circuits is changing the capacitance (C) element onto
the constant phase element (CPE) element (Fig. 4, Table 2).
Fig. 3. Equivalent circuits of Al foil.
Table 2.
Calculations of equivalent circuits of Al foil
Element Freedo
m Value Error Error
%
R3 Free() 0.2601 0.0009 0.35
CPE1-T Free(+) 1.7 E5 62841 37.62
CPE1-P Free() -0.760 0.043 5.633
L1 Free() 2.11E-7 3.3E-8 15.764
Weighted Sum of Squares: 6.3843
Al
Z', Ohm
0,2 0,3 0,4 0,5 0,6 0,7
Z"
,
O
hm
0,0
0,5
1,0
1,5
bent_steklo(3)
Z', Ohm
35 40 45 50 55 60 65 70 75
Z"
,
O
hm
-12
-10
-8
-6
-4
-2
0
2
R3 CPE1 L1
Element Freedom Value Error Error %
R3 Free(±) 0.25702 0.00089849 0.34958
CPE1-T Free(+) 1.6704E5 62841 37.62
CPE1-P Free(±) -0.76007 0.042815 5.633
L1 Free(±) 2.1095E-7 3.3255E-8 15.764
Chi-Squared: 0.10297
Weighted Sum of Squares: 6.3843
Data File: G:\звіт\Конференция\Al.dfr
Circuit Model File: G:\звіт\БРНО\B.mdl
Mode: Run Fitting / Freq. Range (0.01 - 1000000)
Maximum Iterations: 100
Optimization Iterations: 0
Type of Fitting: Complex
Type of Weighting: Calc-Modulus
Fig. 1. The electrochemical analysis set-up.
a b
Fig. 2. Impedance spectra of Al foil (a), Al foil covered by graphene-bentonite mixture (b).
The electrochemical equivalent circuit of
this sample is close to the equivalent circuit
of the oscillatory circuit. The main difference
in these circuits is changing the capacitance
(C) element onto the constant phase element
(CPE) element (Fig. 4, Table 2).
24 ISSN 2708-129X. Укр. хім. журн., 2024
ELECTROCHEMICAL PROPERTIES OF THE ALUMINIUM FILMS WITH GRAPHENE-BENTONITE COVERING.PHISICAL CHEMISTRY
Fig. 3. Equivalent circuits of Al foil.
Table 2.
Calculations of equivalent circuits of Al foil
Element Freedom Value Error Error %
R3 Free(±) 0.2601 0.0009 0.35
CPE1-T Free(+) 1.7 E5 62841 37.62
CPE1-P Free(±) -0.760 0.043 5.633
L1 Free(±) 2.11E-7 3.3E-8 15.764
Weighted Sum of Squares: 6.3843
Such elementcan be characterized by the ele
ment of supercapacitors with non-ideal, CPE
behavior, and the capacitance of CPE circuits
exhibits a power law dependence on potential
sweep rate based on the CPE coefficient n.
Such elementcan be characterized by the element of supercapacitors with non-ideal, CPE behavior,
and the capacitance of CPE circuits exhibits a power law dependence on potential sweep rate based on
the CPE coefficient n.
n
CPE jAZ )(1 . (1)
Reactive resistance X can include capacitive and inductive components that depend on the frequency
of the alternating current supply circuit
𝑋𝑋𝐿𝐿 = 𝜔𝜔𝜔𝜔, 𝑋𝑋𝑐𝑐 = 1 𝜔𝜔𝜔𝜔⁄ . (2)
The addition of reactive components is subject to complex rules. For the serial connection of L and C
in the case of an oscillatory circuit, the expression will be valid:
𝑍𝑍 = √𝑋𝑋2 + 𝑅𝑅2; (3)
𝑋𝑋 = 𝜔𝜔𝜔𝜔 − 1 𝜔𝜔𝜔𝜔. ⁄ (4)
According to eq. 4 for receiving a positive reactive resistance the capacitance should be high and give
the possibility to ignore the value of the 1/ωC in eq. 4.
The calculations of the capacitance value from impedance spectra (Table 3) fully agree with
this statement.The electrostatic capacitance decreases from 0.08 to 0.02 F/g in the frequency range 10-
1÷104 Hz.
The conductivity value is 3.9± 0.1 Sm/cm with decreasing electrostatic capacitance from 0.08
to 0.02 F/g in the frequency range 10-1÷104 Hz. Such behavior is more special for materials with
metallic (electron) types of conductivity (Fig. 4).
Fig.4. Dependence of electrical conductivity on frequency of the Al foil.
The appearance in the equivalent circuit of the CPE element is a formal description of a
complex system, which gives only an external, qualitative appearance, without reflecting the physical
essence of the phenomenon. In this case, CPE is the simplest model, which only formally
approximates a more complex distribution of object parameters, and could be connected with the
Al
F x10n , Hz
-2 -1 0 1 2 3 4 5 6
S
/c
m
3,2
3,3
3,4
3,5
3,6
3,7
3,8
3,9
4,0
(1)
Reactive resistance X can include capacitive
and inductive components that depend on the
frequency of the alternating current supply cir-
cuit
Such elementcan be characterized by the element of supercapacitors with non-ideal, CPE behavior,
and the capacitance of CPE circuits exhibits a power law dependence on potential sweep rate based on
the CPE coefficient n.
n
CPE jAZ )(1 . (1)
Reactive resistance X can include capacitive and inductive components that depend on the frequency
of the alternating current supply circuit
𝑋𝑋𝐿𝐿 = 𝜔𝜔𝜔𝜔, 𝑋𝑋𝑐𝑐 = 1 𝜔𝜔𝜔𝜔⁄ . (2)
The addition of reactive components is subject to complex rules. For the serial connection of L and C
in the case of an oscillatory circuit, the expression will be valid:
𝑍𝑍 = √𝑋𝑋2 + 𝑅𝑅2; (3)
𝑋𝑋 = 𝜔𝜔𝜔𝜔 − 1 𝜔𝜔𝜔𝜔. ⁄ (4)
According to eq. 4 for receiving a positive reactive resistance the capacitance should be high and give
the possibility to ignore the value of the 1/ωC in eq. 4.
The calculations of the capacitance value from impedance spectra (Table 3) fully agree with
this statement.The electrostatic capacitance decreases from 0.08 to 0.02 F/g in the frequency range 10-
1÷104 Hz.
The conductivity value is 3.9± 0.1 Sm/cm with decreasing electrostatic capacitance from 0.08
to 0.02 F/g in the frequency range 10-1÷104 Hz. Such behavior is more special for materials with
metallic (electron) types of conductivity (Fig. 4).
Fig.4. Dependence of electrical conductivity on frequency of the Al foil.
The appearance in the equivalent circuit of the CPE element is a formal description of a
complex system, which gives only an external, qualitative appearance, without reflecting the physical
essence of the phenomenon. In this case, CPE is the simplest model, which only formally
approximates a more complex distribution of object parameters, and could be connected with the
Al
F x10n , Hz
-2 -1 0 1 2 3 4 5 6
S
/c
m
3,2
3,3
3,4
3,5
3,6
3,7
3,8
3,9
4,0
(2)
The addition of reactive components is sub-
ject to complex rules. For the serial connection
of L and C in the case of an oscillatory circuit,
the expression will be valid:
Such elementcan be characterized by the element of supercapacitors with non-ideal, CPE behavior,
and the capacitance of CPE circuits exhibits a power law dependence on potential sweep rate based on
the CPE coefficient n.
n
CPE jAZ )(1 . (1)
Reactive resistance X can include capacitive and inductive components that depend on the frequency
of the alternating current supply circuit
𝑋𝑋𝐿𝐿 = 𝜔𝜔𝜔𝜔, 𝑋𝑋𝑐𝑐 = 1 𝜔𝜔𝜔𝜔⁄ . (2)
The addition of reactive components is subject to complex rules. For the serial connection of L and C
in the case of an oscillatory circuit, the expression will be valid:
𝑍𝑍 = √𝑋𝑋2 + 𝑅𝑅2; (3)
𝑋𝑋 = 𝜔𝜔𝜔𝜔 − 1 𝜔𝜔𝜔𝜔. ⁄ (4)
According to eq. 4 for receiving a positive reactive resistance the capacitance should be high and give
the possibility to ignore the value of the 1/ωC in eq. 4.
The calculations of the capacitance value from impedance spectra (Table 3) fully agree with
this statement.The electrostatic capacitance decreases from 0.08 to 0.02 F/g in the frequency range 10-
1÷104 Hz.
The conductivity value is 3.9± 0.1 Sm/cm with decreasing electrostatic capacitance from 0.08
to 0.02 F/g in the frequency range 10-1÷104 Hz. Such behavior is more special for materials with
metallic (electron) types of conductivity (Fig. 4).
Fig.4. Dependence of electrical conductivity on frequency of the Al foil.
The appearance in the equivalent circuit of the CPE element is a formal description of a
complex system, which gives only an external, qualitative appearance, without reflecting the physical
essence of the phenomenon. In this case, CPE is the simplest model, which only formally
approximates a more complex distribution of object parameters, and could be connected with the
Al
F x10n , Hz
-2 -1 0 1 2 3 4 5 6
S
/c
m
3,2
3,3
3,4
3,5
3,6
3,7
3,8
3,9
4,0
(3)
Such elementcan be characterized by the element of supercapacitors with non-ideal, CPE behavior,
and the capacitance of CPE circuits exhibits a power law dependence on potential sweep rate based on
the CPE coefficient n.
n
CPE jAZ )(1 . (1)
Reactive resistance X can include capacitive and inductive components that depend on the frequency
of the alternating current supply circuit
𝑋𝑋𝐿𝐿 = 𝜔𝜔𝜔𝜔, 𝑋𝑋𝑐𝑐 = 1 𝜔𝜔𝜔𝜔⁄ . (2)
The addition of reactive components is subject to complex rules. For the serial connection of L and C
in the case of an oscillatory circuit, the expression will be valid:
𝑍𝑍 = √𝑋𝑋2 + 𝑅𝑅2; (3)
𝑋𝑋 = 𝜔𝜔𝜔𝜔 − 1 𝜔𝜔𝜔𝜔. ⁄ (4)
According to eq. 4 for receiving a positive reactive resistance the capacitance should be high and give
the possibility to ignore the value of the 1/ωC in eq. 4.
The calculations of the capacitance value from impedance spectra (Table 3) fully agree with
this statement.The electrostatic capacitance decreases from 0.08 to 0.02 F/g in the frequency range 10-
1÷104 Hz.
The conductivity value is 3.9± 0.1 Sm/cm with decreasing electrostatic capacitance from 0.08
to 0.02 F/g in the frequency range 10-1÷104 Hz. Such behavior is more special for materials with
metallic (electron) types of conductivity (Fig. 4).
Fig.4. Dependence of electrical conductivity on frequency of the Al foil.
The appearance in the equivalent circuit of the CPE element is a formal description of a
complex system, which gives only an external, qualitative appearance, without reflecting the physical
essence of the phenomenon. In this case, CPE is the simplest model, which only formally
approximates a more complex distribution of object parameters, and could be connected with the
Al
F x10n , Hz
-2 -1 0 1 2 3 4 5 6
S
/c
m
3,2
3,3
3,4
3,5
3,6
3,7
3,8
3,9
4,0
(4)
According to eq. 4 for receiving a positive
reactive resistance the capacitance should be
high and give the possibility to ignore the value
of the 1/ωC in eq. 4.
The calculations of the capacitance value
from impedance spectra (Table 3) fully agree
with this statement.The electrostatic capac-
itance decreases from 0.08 to 0.02 F/g in the
frequency range 10-1÷104 Hz.
The conductivity value is 3.9± 0.1 Sm/
cm with decreasing electrostatic capacitance
from 0.08 to 0.02 F/g in the frequency range
10-1÷104 Hz. Such behavior is more special for
materials with metallic (electron) types of con-
ductivity (Fig. 4).
Fig.4. Dependence of electrical conductivity on
frequency of the Al foil.
The appearance in the equivalent circuit of
the CPE element is a formal description of a
complex system, which gives only an external,
qualitative appearance, without reflecting the
physical essence of the phenomenon. In this
case, CPE is the simplest model, which only
formally approximates a more complex distri-
bution of object parameters, and could be con-
nected with the presence of aluminum oxides
which take part in the formation of the porous
system on the foil surface, and the mechanical
deformation of the foil.
The impedance spectra of aluminum foil and foil with graphene-bentonite coating have significant
differences in the form of impedance spectra and their electrochemical equivalent circuits (Fig. 2, 3,
6). The EIS spectra of the pure aluminum foil lay in the positive range of reactive resistance
characterized by the impact of the inductance.
a
b
Fig. 2. Impedance spectra of Al foil (a), Al foil covered by graphene-bentonite mixture (b).
The electrochemical equivalent circuit of this sample is close to the equivalent circuit of the
oscillatory circuit. The main difference in these circuits is changing the capacitance (C) element onto
the constant phase element (CPE) element (Fig. 4, Table 2).
Fig. 3. Equivalent circuits of Al foil.
Table 2.
Calculations of equivalent circuits of Al foil
Element Freedo
m Value Error Error
%
R3 Free() 0.2601 0.0009 0.35
CPE1-T Free(+) 1.7 E5 62841 37.62
CPE1-P Free() -0.760 0.043 5.633
L1 Free() 2.11E-7 3.3E-8 15.764
Weighted Sum of Squares: 6.3843
Al
Z', Ohm
0,2 0,3 0,4 0,5 0,6 0,7
Z"
,
O
hm
0,0
0,5
1,0
1,5
bent_steklo(3)
Z', Ohm
35 40 45 50 55 60 65 70 75
Z"
,
O
hm
-12
-10
-8
-6
-4
-2
0
2
R3 CPE1 L1
Element Freedom Value Error Error %
R3 Free(±) 0.25702 0.00089849 0.34958
CPE1-T Free(+) 1.6704E5 62841 37.62
CPE1-P Free(±) -0.76007 0.042815 5.633
L1 Free(±) 2.1095E-7 3.3255E-8 15.764
Chi-Squared: 0.10297
Weighted Sum of Squares: 6.3843
Data File: G:\звіт\Конференция\Al.dfr
Circuit Model File: G:\звіт\БРНО\B.mdl
Mode: Run Fitting / Freq. Range (0.01 - 1000000)
Maximum Iterations: 100
Optimization Iterations: 0
Type of Fitting: Complex
Type of Weighting: Calc-Modulus
Such elementcan be characterized by the element of supercapacitors with non-ideal, CPE behavior,
and the capacitance of CPE circuits exhibits a power law dependence on potential sweep rate based on
the CPE coefficient n.
n
CPE jAZ )(1 . (1)
Reactive resistance X can include capacitive and inductive components that depend on the frequency
of the alternating current supply circuit
𝑋𝑋𝐿𝐿 = 𝜔𝜔𝜔𝜔, 𝑋𝑋𝑐𝑐 = 1 𝜔𝜔𝜔𝜔⁄ . (2)
The addition of reactive components is subject to complex rules. For the serial connection of L and C
in the case of an oscillatory circuit, the expression will be valid:
𝑍𝑍 = √𝑋𝑋2 + 𝑅𝑅2; (3)
𝑋𝑋 = 𝜔𝜔𝜔𝜔 − 1 𝜔𝜔𝜔𝜔. ⁄ (4)
According to eq. 4 for receiving a positive reactive resistance the capacitance should be high and give
the possibility to ignore the value of the 1/ωC in eq. 4.
The calculations of the capacitance value from impedance spectra (Table 3) fully agree with
this statement.The electrostatic capacitance decreases from 0.08 to 0.02 F/g in the frequency range 10-
1÷104 Hz.
The conductivity value is 3.9± 0.1 Sm/cm with decreasing electrostatic capacitance from 0.08
to 0.02 F/g in the frequency range 10-1÷104 Hz. Such behavior is more special for materials with
metallic (electron) types of conductivity (Fig. 4).
Fig.4. Dependence of electrical conductivity on frequency of the Al foil.
The appearance in the equivalent circuit of the CPE element is a formal description of a
complex system, which gives only an external, qualitative appearance, without reflecting the physical
essence of the phenomenon. In this case, CPE is the simplest model, which only formally
approximates a more complex distribution of object parameters, and could be connected with the
Al
F x10n , Hz
-2 -1 0 1 2 3 4 5 6
S
/c
m
3,2
3,3
3,4
3,5
3,6
3,7
3,8
3,9
4,0
25https://ucj.org.ua
O.V. Boychuk, K. D. Pershina UCJ № 5 / Vol. 90
Applying the graphene-bentonite coating
changes the type of conductivity from electron
type to ionic type.
Table 3
Capacitance data in the frequency range
102-104
F, Hz C,F /g Al
C,F/gAl +
Graphene with
bentonite
1484,9710 0,0195 1,3978e-5
849,7515 0,0418 2,6147e-5
486,2609 0,0751 3,7145e-5
278,2561 0,0710 6,7204e-5
159,2297 0,0840 1,3327e-4
91,1166 0,0846 1,8769e-4
In case of the ionic type, the conductivity
rises with increasing frequancy, butconducti
vity has two orders smaller value, and rises
with increasing the frequency from 0.014 to
0.02 Sm/cm (Fig. 5).
Fig. 5. Dependence of electrical conductivity on
frequency of Al foil covered by graphene-bentonite
mixtures.
The view of the impedance spectrum
(Fig. 2 b) and the electrochemical equivalent
circuit (Fig. 6, Table 4) also change in the case
of covering by graphene-bentonite mixtures. It
has a view that looks like the ZARC element
(R-CPE parallel circuit) for porous electrodes
of a supercapacitor [9, 10].
Fig. 6. Equivalent circuits of Al foil covered by
covered by graphene-bentonite mixture.
Table 4.
Calculations of equivalent circuits of Al
foil covered by covered by graphene-bento
nite mixture.
Element Freedom Value Error Error %
R1 Free(±) 23.88 1.510 6.32
CPE1-T Free(±) 1.378E-5 1.63 E-6 11.87
CPE1-P Free(±) 0.5207 0.0124 2.40
R3 Free(±) 47.56 1.551 3.26
Weighted Sum of Squares: 6.3843
The presence of such a circuit exhibits the
electrochemical double layer capacitors (su-
percapacitors) with non-ideal CPE element be-
haviour, and spectra fully lays in a negative va
lue of the reactive resistance [9]. The presence
of a dielectric component (bentonite) on the
foil surface limits the polarization of composite
material (Fig. 2. b) and decreases capacitance
value (Table 3). Received equvalent model is
very close to model of the porous electrode in
the self-discharging conditions [10].
presence of aluminum oxides which take part in the formation of the porous system on the foil
surface, and the mechanical deformation of the foil.
Applying the graphene-bentonite coating changes the type of conductivity from electron type
to ionic type.
Table 3
Capacitance data in the frequency range 102-104
In case of the ionic type, the conductivity rises with increasing frequancy, butconductivity has two
orders smaller value, and rises with increasing the frequency from 0.014 to 0.02 Sm/cm (Fig. 5).
Fig. 5. Dependence of electrical conductivity on frequency of Al foil covered by graphene-bentonite mixtures.
The view of the impedance spectrum (Fig. 2 b) and the electrochemical equivalent circuit (Fig. 6,
Table 4) also change in the case of covering by graphene-bentonite mixtures. It has a view that looks
like the ZARC element (R-CPE parallel circuit) for porous electrodes of a supercapacitor [9, 10].
Fig. 6. Equivalent circuits of Al foil covered by covered by graphene-bentonite mixture.
Table 4.
Calculations of equivalent circuits of Al foil covered by covered by graphene-bentonite mixture.
Element Freedom Value Error Error
%
R1 Free() 23.88 1.510 6.32
Z ' bent_steklo(3)
F x10n , Hz
-2 -1 0 1 2 3 4 5 6
, S
/c
m
0,013
0,014
0,015
0,016
0,017
0,018
0,019
R1 CPE1
R3
Element Freedom Value Error Error %
R1 Free(±) 23.88 1.5098 6.3224
CPE1-T Free(±) 1.3779E-5 1.6354E-6 11.869
CPE1-P Free(±) 0.52077 0.012492 2.3988
R3 Free(±) 47.56 1.551 3.2611
Chi-Squared: 0.24991
Weighted Sum of Squares: 15.494
Data File: G:\звіт\Конференция\bent_steklo(3).dfr
Circuit Model File: F:\models\1.mdl
Mode: Run Fitting / Selected Points (0 - 32)
Maximum Iterations: 200
Optimization Iterations: 4
Type of Fitting: Complex
Type of Weighting: Unit Weighting
F, Hz C,F /g Al C,F/gAl+Graphene with bentonite
1484,9710 0,0195 1,3978e-5
849,7515 0,0418 2,6147e-5
486,2609 0,0751 3,7145e-5
278,2561 0,0710 6,7204e-5
159,2297 0,0840 1,3327e-4
91,1166 0,0846 1,8769e-4
presence of aluminum oxides which take part in the formation of the porous system on the foil
surface, and the mechanical deformation of the foil.
Applying the graphene-bentonite coating changes the type of conductivity from electron type
to ionic type.
Table 3
Capacitance data in the frequency range 102-104
In case of the ionic type, the conductivity rises with increasing frequancy, butconductivity has two
orders smaller value, and rises with increasing the frequency from 0.014 to 0.02 Sm/cm (Fig. 5).
Fig. 5. Dependence of electrical conductivity on frequency of Al foil covered by graphene-bentonite mixtures.
The view of the impedance spectrum (Fig. 2 b) and the electrochemical equivalent circuit (Fig. 6,
Table 4) also change in the case of covering by graphene-bentonite mixtures. It has a view that looks
like the ZARC element (R-CPE parallel circuit) for porous electrodes of a supercapacitor [9, 10].
Fig. 6. Equivalent circuits of Al foil covered by covered by graphene-bentonite mixture.
Table 4.
Calculations of equivalent circuits of Al foil covered by covered by graphene-bentonite mixture.
Element Freedom Value Error Error
%
R1 Free() 23.88 1.510 6.32
Z ' bent_steklo(3)
F x10n , Hz
-2 -1 0 1 2 3 4 5 6
, S
/c
m
0,013
0,014
0,015
0,016
0,017
0,018
0,019
R1 CPE1
R3
Element Freedom Value Error Error %
R1 Free(±) 23.88 1.5098 6.3224
CPE1-T Free(±) 1.3779E-5 1.6354E-6 11.869
CPE1-P Free(±) 0.52077 0.012492 2.3988
R3 Free(±) 47.56 1.551 3.2611
Chi-Squared: 0.24991
Weighted Sum of Squares: 15.494
Data File: G:\звіт\Конференция\bent_steklo(3).dfr
Circuit Model File: F:\models\1.mdl
Mode: Run Fitting / Selected Points (0 - 32)
Maximum Iterations: 200
Optimization Iterations: 4
Type of Fitting: Complex
Type of Weighting: Unit Weighting
F, Hz C,F /g Al C,F/gAl+Graphene with bentonite
1484,9710 0,0195 1,3978e-5
849,7515 0,0418 2,6147e-5
486,2609 0,0751 3,7145e-5
278,2561 0,0710 6,7204e-5
159,2297 0,0840 1,3327e-4
91,1166 0,0846 1,8769e-4
26 ISSN 2708-129X. Укр. хім. журн., 2024
ELECTROCHEMICAL PROPERTIES OF THE ALUMINIUM FILMS WITH GRAPHENE-BENTONITE COVERING.PHISICAL CHEMISTRY
CONCLUSIONS. The experiment and cal-
culations of conductivity and capacity of Al-
graphene-bentonite composites established
that the application of the graphene-bentonite
coating forms an additional surface capacity
that participates in the preservation of the elect
rical energy and protects the conductive carri-
er from electrical loss under the oxidation on
the open air. Such an effect can be received due
to the formation of the bentonite-graphene po-
rous electrode with a self-discharging ability.
The work was carried out with the sup-
port from the National Academy of
Sciences of Ukraine with in the budget
program 316 NT "Development of ma-
terials and processes for the extraction of va
luable and toxic components from liquids of
biogenic and technogenic origin".
ЕЛЕКТРОХІМІЧНІ ВЛАСТИВОСТІ АЛЮМІНІ-
ЄВИХ ПЛІВОК ІЗ ГРАФЕН-БЕНТОНІТОВИМ
ПОКРИТТЯМ
O. В. Бойчук1, K. Д. Першина2
1 Інститут загальної та неорганічної хімії
ім. В. І. Вернадського НАН України,
просп. Акад. Палладіна, 32/34, Київ 03142,
Україна;
2 Міжвідомче відділення електрохімічної
енергетики НАН України,
просп. Акад. Вернадського, 38 А, Київ 03680,
Україна
E-mail: 9spiritlucker9@gmail.com
Обговорено зміни типу провідності,
значення ємності та моделі еквівалентної
схеми композиційних матеріалів з ураху-
ванням впливу графен-бентонітових по-
криттів на алюмінієвий носій. Спектри EIS
чистої алюмінієвої фольги лежать в області
позитивного реактивного опору, що харак-
теризується впливом індуктивності. Вели-
чина електропровідності 3,9±0,1 См/см при
спадній електростатичній ємності від 0,08
до 0,02 Ф/г в діапазоні частот 10-1÷104 Гц.
Нанесення графен-бентонітового покриття
змінює типи провідності, від електронного
до іонного. Електропровідність має на два
порядки менше значення і зростає зі збіль-
шенням частоти від 0,014 до 0,02 См/см.
Електрохімічна еквівалентна схема у ви-
падку покриття графен-бентонітовими
сумішами – паралельна схема R-CPE має
характеристику пористих електродів у су-
перконденсаторі. Наявність на поверхні
фольги діелектричної складової (бентоні-
ту) обмежує поляризацію композиційного
матеріалу та зменшує величину ємності.
Ключові слова: графен, бентоніт, алюмі-
нієва фольга, композитний матеріал, елект
ропровідність, ємність.
REFERENCES
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Cтаття надійшла 12.02.2024.
|
| id | oai:ojs2.1444248.nisspano.web.hosting-test.net:article-664 |
| institution | Ukrainian Chemistry Journal |
| keywords_txt_mv | keywords |
| language | English |
| last_indexed | 2026-07-23T01:11:44Z |
| publishDate | 2024 |
| publisher | V.I.Vernadsky Institute of General and Inorganic Chemistry |
| record_format | ojs |
| resource_txt_mv | ucjorgua/35/40cf3715e44e43eabc53cd94e34c3035.pdf |
| spelling | oai:ojs2.1444248.nisspano.web.hosting-test.net:article-6642026-07-22T08:23:54Z ELECTROCHEMICAL PROPERTIES OF THE ALUMINIUM FILMS WITH GRAPHENE-BENTONITE COVERING Boichuk, Oleksandr Pershina, Katherine graphene, bentonite, aluminium foil, composite material, conductivity, capacity. The changes in the conductivity type, capacitance value, and equivalent circuit models of the composite materials, taking into account the impact of graphene-bentonite covers on the aluminum carrier, are discussed. The EIS spectra of the pure aluminum foil lay in the positive reactive resistance domain characterized by the impact of the inductance. The conductivity value is 3.9± 0.1 Sm/cm with decreasing electrostatic capacitance from 0.08 to 0.02 F/g in the frequency range 10-1÷104 Hz. Applying the graphene-bentonite coating changes types of conductivity, from electron type to ionic type. Conductivity has two orders smaller value, and rises with increasing the frequency from 0.014 to 0.02 Sm/cm. The electrochemical equivalent circuit in the case of covering by graphene-bentonite mixtures is the R-CPE parallel circuit has characteristic of the porous electrodes in a supercapacitor. Presence of a dielectric component (bentonite) on the foil surface limits the polarization of composite material and decreases the capacitance value. V.I.Vernadsky Institute of General and Inorganic Chemistry 2024-06-28 Article Article Physical chemistry Физическая xимия Фізична xімія application/pdf https://ucj.org.ua/index.php/journal/article/view/664 10.33609/2708-129X.90.5.2024.21-27 Ukrainian Chemistry Journal; Vol. 90 No. 5 (2024): Ukrainian Chemistry Journal; 21-27 Украинский химический журнал; ##issue.vol## 90 ##issue.no## 5 (2024): Ukrainian Chemistry Journal; 21-27 Український хімічний журнал; Том 90 № 5 (2024): Ukrainian Chemistry Journal; 21-27 2708-129X 2708-1281 en https://ucj.org.ua/index.php/journal/article/view/664/330 Copyright (c) 2024 Oleksandr Boichuk, Katherine Pershina https://creativecommons.org/licenses/by-nc/4.0 |
| spellingShingle | Boichuk, Oleksandr Pershina, Katherine ELECTROCHEMICAL PROPERTIES OF THE ALUMINIUM FILMS WITH GRAPHENE-BENTONITE COVERING |
| title | ELECTROCHEMICAL PROPERTIES OF THE ALUMINIUM FILMS WITH GRAPHENE-BENTONITE COVERING |
| title_full | ELECTROCHEMICAL PROPERTIES OF THE ALUMINIUM FILMS WITH GRAPHENE-BENTONITE COVERING |
| title_fullStr | ELECTROCHEMICAL PROPERTIES OF THE ALUMINIUM FILMS WITH GRAPHENE-BENTONITE COVERING |
| title_full_unstemmed | ELECTROCHEMICAL PROPERTIES OF THE ALUMINIUM FILMS WITH GRAPHENE-BENTONITE COVERING |
| title_short | ELECTROCHEMICAL PROPERTIES OF THE ALUMINIUM FILMS WITH GRAPHENE-BENTONITE COVERING |
| title_sort | electrochemical properties of the aluminium films with graphene-bentonite covering |
| topic_facet | graphene bentonite aluminium foil composite material conductivity capacity. |
| url | https://ucj.org.ua/index.php/journal/article/view/664 |
| work_keys_str_mv | AT boichukoleksandr electrochemicalpropertiesofthealuminiumfilmswithgraphenebentonitecovering AT pershinakatherine electrochemicalpropertiesofthealuminiumfilmswithgraphenebentonitecovering |