Hybrid electrochemical supercapacitors based on aqueous electrolyte solutions
In this paper it was investigated the system of the hybrid iodine electrochemical supercapacitor, which provides the discharge capacity over 7500 F/g. Microporous carbon material obtained by high temperature steam activation of the natural raw materials was used as an anode material for electrodes...
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Науковий фізико-технологічний центр МОН та НАН України
2012
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| Цитувати: | Hybrid electrochemical supercapacitors based on aqueous electrolyte solutions / B.P. Bakhmatyuk, A.S. Kurepa // Физическая инженерия поверхности. — 2012. — Т. 10, № 3. — С. 281–285. — Бібліогр.: 14 назв. — англ. |
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irk-123456789-989722016-04-20T03:02:45Z Hybrid electrochemical supercapacitors based on aqueous electrolyte solutions Bakhmatyuk, B.P. Kurepa, A.S. In this paper it was investigated the system of the hybrid iodine electrochemical supercapacitor, which provides the discharge capacity over 7500 F/g. Microporous carbon material obtained by high temperature steam activation of the natural raw materials was used as an anode material for electrodes preparation. Moreover, the system of hybrid alkaline electrochemical supercapacitor was investigated, and it was proved, that additional activation of the activated carbon material in the molten NaOH can increase the available for charge surface of the material. As a result, discharge capacity per weight of active material can increase up to 342 F/g and the energy density is 6.5 times greater than value of known symmetric supercapacitors. Вроботі використовуючи мікропористий вуглецевий матеріал, отриманий високотемпературною активацією у водяній парі природньої сировини, досліджена система йодидного гібридного електрохімічного суперконденсатора, що забезпечує питому ємність на розряді понад 7500 Ф/г. Досліджена система лужного гібридного електрохімічного суперконденсатора і доведено, що доактивація активованого вуглецевого матеріалу в розплаві NaOH дозволяє підвищити доступну до заряду поверхню матеріалу. І як результат дозволяє підвищити розрядну ємність на масу активного матеріалу до 342 Ф/г та збільшує питому енергоємність в 6,5 разів у порівнянніз відомими симетричними суперконденсаторами. В работе используя микропористый углеродный материал, полученный высокотемпературной активацией в водяном паре естественного сырья, исследована система йодидного гибридного электрохимического суперконденсатора, которая обеспечивает удельную емкость на разряде свыше 7500 Ф/г. Исследована система щелочного гибридного электрохимического суперконденсатора и доказано, что дополнительная активация активированного углеродного материала в расплаве NaOH, позволяет повысить доступную для заряда поверхность материала. И как результат позволяет повысить разрядную емкость на массу активного материала до 342 Ф/г и увеличивает удельную энергоемкость в 6,5 раз по сравнению с известными симметричными суперконденсаторами. 2012 Article Hybrid electrochemical supercapacitors based on aqueous electrolyte solutions / B.P. Bakhmatyuk, A.S. Kurepa // Физическая инженерия поверхности. — 2012. — Т. 10, № 3. — С. 281–285. — Бібліогр.: 14 назв. — англ. 1999-8074 http://dspace.nbuv.gov.ua/handle/123456789/98972 541.136.88, 541.135, 544.65 en Физическая инженерия поверхности Науковий фізико-технологічний центр МОН та НАН України |
| institution |
Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| collection |
DSpace DC |
| language |
English |
| description |
In this paper it was investigated the system of the hybrid iodine electrochemical supercapacitor,
which provides the discharge capacity over 7500 F/g. Microporous carbon material obtained by high
temperature steam activation of the natural raw materials was used as an anode material for electrodes
preparation. Moreover, the system of hybrid alkaline electrochemical supercapacitor was investigated,
and it was proved, that additional activation of the activated carbon material in the molten NaOH can
increase the available for charge surface of the material. As a result, discharge capacity per weight
of active material can increase up to 342 F/g and the energy density is 6.5 times greater than value of
known symmetric supercapacitors. |
| format |
Article |
| author |
Bakhmatyuk, B.P. Kurepa, A.S. |
| spellingShingle |
Bakhmatyuk, B.P. Kurepa, A.S. Hybrid electrochemical supercapacitors based on aqueous electrolyte solutions Физическая инженерия поверхности |
| author_facet |
Bakhmatyuk, B.P. Kurepa, A.S. |
| author_sort |
Bakhmatyuk, B.P. |
| title |
Hybrid electrochemical supercapacitors based on aqueous electrolyte solutions |
| title_short |
Hybrid electrochemical supercapacitors based on aqueous electrolyte solutions |
| title_full |
Hybrid electrochemical supercapacitors based on aqueous electrolyte solutions |
| title_fullStr |
Hybrid electrochemical supercapacitors based on aqueous electrolyte solutions |
| title_full_unstemmed |
Hybrid electrochemical supercapacitors based on aqueous electrolyte solutions |
| title_sort |
hybrid electrochemical supercapacitors based on aqueous electrolyte solutions |
| publisher |
Науковий фізико-технологічний центр МОН та НАН України |
| publishDate |
2012 |
| url |
http://dspace.nbuv.gov.ua/handle/123456789/98972 |
| citation_txt |
Hybrid electrochemical supercapacitors based on aqueous electrolyte solutions / B.P. Bakhmatyuk, A.S. Kurepa // Физическая инженерия поверхности. — 2012. — Т. 10, № 3. — С. 281–285. — Бібліогр.: 14 назв. — англ. |
| series |
Физическая инженерия поверхности |
| work_keys_str_mv |
AT bakhmatyukbp hybridelectrochemicalsupercapacitorsbasedonaqueouselectrolytesolutions AT kurepaas hybridelectrochemicalsupercapacitorsbasedonaqueouselectrolytesolutions |
| first_indexed |
2025-07-07T07:17:16Z |
| last_indexed |
2025-07-07T07:17:16Z |
| _version_ |
1836971602720325632 |
| fulltext |
281
INTRODUCTION
Electrochemical supercapacitors (SC) are power
sources, which occupy an intermediate position
between batteries and conventional capacitors. They
are dynamically developing [2, 3] starting from the
first patent for SC [1]. There are three main types
of electrochemical supercapacitors:
− double layer capacitors (DLC), which consist
of ideally polarized electrodes (often from
activated carbon) in organic and aqueous
solutions of electrolytes [4];
− so-called pseudocapacitors, capacity of which
is provided by a pseudocapacity of Faraday
processes of polymers and metal oxides. For
example, a pseudocapacity of hydrogenation-
dehydrogenation of ruthenium oxides [5];
− hybrid electrochemical s upercapacitors
(HESC), which contain well polarized electrode,
based on activated carbon material and almost
unpolarized counter electrode in electrolyte
systems. This allows to twice the growing of
potential change of the carbon electrode and the
UDC 541.136.88, 541.135, 544.65
HYBRID ELECTROCHEMICAL SUPERCAPACITORS BASED ON AQUEOUS
ELECTROLYTE SOLUTIONS
B.P. Bakhmatyuk, A.S. Kurepa
National University “Lviv Polytechnic”
Ukraine
Received 02.07.2012
In this paper it was investigated the system of the hybrid iodine electrochemical supercapacitor,
which provides the discharge capacity over 7500 F/g. Microporous carbon material obtained by high
temperature steam activation of the natural raw materials was used as an anode material for electrodes
preparation. Moreover, the system of hybrid alkaline electrochemical supercapacitor was investigated,
and it was proved, that additional activation of the activated carbon material in the molten NaOH can
increase the available for charge surface of the material. As a result, discharge capacity per weight
of active material can increase up to 342 F/g and the energy density is 6.5 times greater than value of
known symmetric supercapacitors.
Keywords: ultracapacitor, electrochemistry, pseudocapacitance, activated carbon, hybrid super-
capacitor.
В роботі використовуючи мікропористий вуглецевий матеріал, отриманий високотемпературною
активацією у водяній парі природньої сировини, досліджена система йодидного гібридного елект-
рохімічного суперконденсатора, що забезпечує питому ємність на розряді понад 7500 Ф/г. До-
сліджена система лужного гібридного електрохімічного суперконденсатора і доведено, що до-
активація активованого вуглецевого матеріалу в розплаві NaOH дозволяє підвищити доступну
до заряду поверхню матеріалу. І як результат дозволяє підвищити розрядну ємність на масу
активного матеріалу до 342 Ф/г та збільшує питому енергоємність в 6,5 разів у порівнянні з ві-
домими симетричними суперконденсаторами.
Ключові слова: суперконденсатор, електрохімія, псевдоємність, активоване вугілля, гібридний
іоністор.
В работе используя микропористый углеродный материал, полученный высокотемпературной
активацией в водяном паре естественного сырья, исследована система йодидного гибридного
электрохимического суперконденсатора, которая обеспечивает удельную емкость на разряде
свыше 7500 Ф/г. Исследована система щелочного гибридного электрохимического суперконден-
сатора и доказано, что дополнительная активация активированного углеродного материала в
расплаве NaOH, позволяет повысить доступную для заряда поверхность материала. И как
результат позволяет повысить разрядную емкость на массу активного материала до 342 Ф/г и
увеличивает удельную энергоемкость в 6,5 раз по сравнению с известными симметричными
суперконденсаторами.
Ключевые слова: суперконденсатор, электрохимия, псевдоемкость, активированный уголь,
гибридный ионистор.
B.P. Bakhmatyuk, A.S. Kurepa, 2012
ФІП ФИП PSE, 2012, т. 10, № 3 vol. 10, No. 3282
capacitance value of the unit, compared to the
DLC, due to absence of the second serial
polarized electrode in an equivalent electrical
circuit. These factors can increase the energy of
HESC some 2 to 5 times by comparison with
the symmetrical design [6, 7].
However, existing electrochemical capacitor
electrodes cannot provide capacity greater than 900
F/g, so it does not meet growing needs of various
branches of engineering and automotive industry [4].
For example, if the HESC [6] is the system of not
polarized electrode PbO2|PbSO4 and negative well
polarized activated carbon electrode, between
which the separator with an aqueous solution of
sulfuric acid is located. In such system implementation
of the total reaction is:
PbO2+ 2H2SO4 + (H+)ad|E
–
s ↔ PbSO4 +2H2O +
+ (HSO–
4)ad| E
+
s, (1)
where Es is surface of the electrode.
This system provides a capacitance of carbon
electrode up to 600 F/g. The disadvantages of such
systems are much smaller electrical capacities of the
theoretically calculated for hybrid electrochemical
capacitors, and low values of energy at considerable
cost to the manufacture and using environmentally
hazardous materials. Constantly growing demands
of engineering and electronics can be satisfied only
with much more power-consuming and more
powerful devices with low cost and environmental
cleanliness.
Objective of this paper is to create HESC with
no polarized electrode and well polarized electrode
based on activated carbon, which would provide
tenfold increasing in electrical capacity, which would
let increasing of the energy content, while using only
environmentally friendly materials and lower cost of
its production.
EXPERIMENTAL
Isotherms of the nitrogen adsorption were obtained
by using Quantachrome NovaWin − Quantachrome
Instruments (version 11.0). HESC have been
jacketed into blister foil (fig. 1). They consist of
polarized carbon electrode and unpolarized zinc-
metal electrode divided by the separator with
electrolyte and current collectors, which was made
of stainless steel. The positive electrode was made
from activated carbon with the addition of 3% teflon
binder. It represents a square thin film, with 3 sm si-
de, which thickness is 60 − 86 мm. For this purpose,
it was used activated carbon with the surface area
1246 − 1377 m2/g. Coal film was pressed onto the
current collector. Unpolarized electrode was made
by prior electroplating of the metal onto the current
collector with the layer thickness of 40 мm. Appo-
inted electrodes was divided by a separator
BAHYT-48 tacked in two layers, which was pre-
viously immersed in a water solution of 30% KOH
or 20%LiI + 15%ZnCl2. Charge and discharge
characteristics were investigated with a help of
AUTOLAB measuring complex made in Nether-
lands by “ECO CHEMIE”.
RESULTS AND DISCUSSION
Initial activated carbon material (ACM) was ob-
tained by high temperature carbonization and ac-
tivation of apricot seeds in water vapor at 950 °С.
The BET surface area of material was 1246 m2/g,
according to nitrogen adsorption isotherms at 77 K
(fig. 2a).
ACM was subjected to the activation in the melt
of sodium hydroxide. Homogeneous mixture of
material with fivefold weight of sodium hydroxide
was heated in an atmosphere of argon from room
temperature to 500 °С with speed of 20 °С per
minute and it was held at this temperature for
30 min. Thus additionally activated material was
washed in warm water from alkali and dried. The
resulting activated material (ACMR) had a BET
surface value equal to 1377 m2/g (fig. 2b).
The resulting ACM was tested in the system of
symmetric SC in aqueous 30% KOH. Galvanostatic
charge-discharge results (fig. 3) was showed typi-
Fig. 1. Schematic structure of fabricated HESC prototype.
HYBRID ELECTROCHEMICAL SUPERCAPACITORS BASED ON AQUEOUS ELECTROLYTE SOLUTIONS
283
cally high value of the coulomb cycle efficiency
η = 99% and the capacitance C = 186 F/g. Ac-
cording to the data represented in paper [8], it cor-
responds to 986 m2/g of available surface for po-
tassium ions charging by the equation:
Сх + K+ + e− = E−
s||K
+ , (2)
here Сх – surface of the porous structure of the
ACM, K+ – cations of the electrolyte, || – dual layer,
where charge is accumulated by the mechanism of
physical adsorption.
The resulting value of C = 186 F/g is insufficient
to build a competitive SC. Therefore, it was inves-
tigated the system of HESC, which contains positive
polarized electrode based on ACMR and negative
unpolarized zinc electrode, divided by a separator
immersed in an aqueous 30% KOH. There is well
reverse process (2) on the positive carbon elect-
rode. And as well, reverse electrode process in al-
kaline medium of zinc-metal anode occurs on the
negative electrode:
Zn + 2ОН– = ZnO + H2O +2e−. (3)
Thus the total reaction which is implemented in
the capacitor will look like:
2Cx + 2K+ + ZnO + H2O = 2Cx||K
+ + Zn + 2ОН−.
(4)
Fig. 4 illustrates charge-discharge cycle of the
proposed HESC. Cycle recorded in galvanostatic
mode with current density i = 1 A/g, which is cal-
culated for an active mass of the working electrode.
Discharge presented in fig. 4 is corresponding to
the capacity С = ∆Qd/∆U = 287 C/g/0.84 V =
= 342 F/g with a coulombic efficiency of the cycle
η = (∆Qd/∆Qc)⋅100% = (287/290)⋅100% = 99%,
where ∆Qd, ∆Qc – amount of charging and dischar-
ging electricity of the cycle. Significant increase in
discharge capacity is related to increase of available
for charge (by equation (2)) surface of ACMR up
to 1100 m2/g. Charging-discharging of ACMR is oc-
curs in the electrode potentials from 0.04 to −0,9 V
according to the standard hydrogen electrode.
Ragone dependence (fig. 5) has been calculated
in the coordinates of energy density v. power density
(W – P), submitted to the masses of both electrodes.
For this, it was recorded galvanostatic cycles with
different current loadings (from 1 to 5 A/g).
The discharge energy was determined by the
equation:
a)
b)
Fig. 2. Nitrogen adsorption isotherm for activated (a) and
additionally activated in NaOH (b) carbon material.
Fig. 3. Galvanostatic cycle of symmetric SC in 30% aqueous
solution of KOH (current density is i = 1 A/g).
Fig. 4. The cycle of galvanostatic charge-discharge of
proposed HESC with current density i = 1 A/g.
B.P. BAKHMATYUK, A.S. KUREPA,
ФІП ФИП PSE, 2012, т. 10, № 3 vol. 10, No. 3
ФІП ФИП PSE, 2012, т. 10, № 3 vol. 10, No. 3284
2 2
2 1
1 2
311 F/g
2
U UCW
m m
−= ⋅ = ×
+
2 2
21.23 0.4 V 211 J/g 59 mW h/g
2
−× = = ⋅ , (5)
where C – capacity represented to the active mass
of both electrodes (m1 m2), U2 and U1 – voltage of
beginning and expiration of the discharge, respec-
tively. The power of discharge was determined ac-
cording to the next equation: P = i⋅Uav= 0.91A/g×
×0.82 V = 0.74 W/g, here Uavr– discharge volta-
ge, which corresponds to 0.5∆Qd. Coulombic
efficiency of cycling was within 95 − 98%
The proposed alkaline HESC ensures 6.5 times
increase at the energy obtained with a more than
ninefold increase at the current load, compared to
the alkaline symmetrical electrochemical super-
capacitors [9 − 11]. For comparison of investigated
energy storage systems with known lead acid and
alkaline cadmium-nickel batteries, we assume that
the proposed alkaline HESC will contain 30% by
weight of active components of the cathode. That
case values of the energy density and power power
density listed to the device will be P = 222 W/kg
and W = 18 W⋅h/kg. Using data obtained from the
high currents discharge [12] for lead battery
(P = 90 W/kg and W = 9 W⋅h/kg) and for the
cadmium-nickel batteries (P = 200 W/kg and
W = 10 W⋅h/kg) we find, that the proposed HESC
system shows double increase of both parameters
compared to the lead battery, and shows an 1.8 ti-
mes increase in the energy intensity with simul-
taneously little power increase, with the comparison
to the cadmium-nickel battery.
The ability of microporous activated carbon
materials to charge up to 2000 F/g at the positive
electrode polarization, which does not reach the
potential of iodine allocation in the free state, has
been shown in articles [13, 14]. Therefore, this article
investigates iodine HESC, which has polarized, on
the basis of ACM with S = 1246 m2/g, and unpola-
rized metal electrodes, between which the separator
with 20%LiI + 15%ZnCl2 dissolved in water is loca-
ted. Consideration of the most well-known from the
literature values for iodine index of activated carbon
materials – 1.1 mg/m2, and the electrochemical
equivalent of iodine 13.16⋅10−-4 g/C, we have cal-
culated the maximum electric charge of the surfa-
ce by iodine atoms – qІ = 0.836 C/m2. In this ca-
se, the maximum calculated electric charge for
our investigational ACM is С = 0.836 C/m2×
×1246 m2/g = 1042 C/g. Metallic zinc was used as
an unpolarized electrode material. The system of
iodine HESC can be represented as follows:
(−)Zn|Zn2+, I−|CхI(+). (6)
Well reverse process of electrochemical in-
tercalation of ions into the pores with diameter
d ≥ 0.45 nm occurs at polarized carbon electrodes:
CxІ + e– ↔ Cx + І–, (7)
where х = 9. Process of electrolytic deposition and
anodic dissolution of metal is occurs at unpolarized
electrode:
Zn2+ + 2e− = Zn. (8)
Overall current creative process of iodine HESC
can be represented as follows:
CхI + 0.5Zn = Cх + I− + 0.5Zn2+. (9)
Manufactured HESC was charged in the po-
tentiostatic mode at the potential of 1.25 V for two
hours and discharged in the galvanostatic mode with
value of current density – 480 mA/g (fig. 6).
The resulting value of capacitance is equal to
С = 834.75 C/g/0.11 V = 7589 F/g, which is
calculated to the polarized electrode active material,
which is 12,8 times greater than the maximum
capacity of carbon electrode reported in the literature
[6]. The discharge capacity and the electrical
capacity of iodine HESC (fig. 6) values was
P = 420 W and W = 214 W⋅h per 1 kg of active
mass of used electrodes. Assume that the proposed
iodine HESC will contain 25% by weight of active
components of the cathode, for comparison in-
vestigated system of iodine HESC with known lead
acid batteries and alkaline cadmium-nickel batteries.
Fig. 5. Ragone dependence for investigated alkaline HESC.
HYBRID ELECTROCHEMICAL SUPERCAPACITORS BASED ON AQUEOUS ELECTROLYTE SOLUTIONS
285
Then the value of these physical quantities at device
will be P = 105 W/kg and W = 53.5 W⋅h/kg, which
is 6 times higher than energy consumption of lead
battery with comparable power.
CONCLUSIONS
1. High temperature activation of apricot seeds in
water vapor provides a microporous activated
carbon material with the surface by BET equal
to 1246 m2/g, and its further activation at melted
NaOH increases the specific surface area to
1377 m2/g.
2. Using additionally activated carbon material in
the system of alkaline hybrid electrochemical
supercapacitor provide 6.5 times increasing of
the energy obtained in more than ninefold in-
crease in the current load, in comparison with
alkaline symmetrical electrochemical super-
capacitors.
3. As cathode component of the iodine hybrid
electrochemical supercapacitor investigated
activated carbon material provides capacity that
is 12.8 times exceeds the maximum capacity of
carbon electrodes, which was reported in
literature. Obtained values of discharge power
and electrical capacity for this system reached
P = 420 W and W = 214 W⋅h per 1 kg of acti-
ve mass of used electrodes.
4. There are perspective of design and techno-
logical work to create the appropriate device,
because comparing the discharge characteristics
of the investigated hybrid electrochemical
supercapacitors with lead acid battery show the
predominance of the first.
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Fig. 6. Galvanostatic discharge of iodine HESC with current
density 480 mA/g.
B.P. BAKHMATYUK, A.S. KUREPA,
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