Новий протонпровідний електроліт для високотемпературних паливних елементів на основі гідрофобної солі гуанідину
Guanidine salts are promising proton conductors due to the high content of exchangeable protons in guanidinium cation that ensure an efficient proton transfer along hydrogen-bonded network formed by proton donor and proton acceptor sites. However, the high melting point of most guanidine salts is a...
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| Date: | 2021 |
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V.P. Kukhar Institute of Bioorganic Chemistry and Petrochemistry of the National Academy of Sciences of Ukraine
2021
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Catalysis and petrochemistry| _version_ | 1872009025506246656 |
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| author | Rogalsky, S.P. Tarasyuk, O.P. Povazhnyi, V.A. Cherniavska, T.V. Makhno, S.M. |
| author_facet | Rogalsky, S.P. Tarasyuk, O.P. Povazhnyi, V.A. Cherniavska, T.V. Makhno, S.M. |
| author_institution_txt_mv | [
{
"author": "S.P. Rogalsky",
"institution": "V.P. Kukhar Institute of Bioorganic Chemistry and Petrochemistry of the National Academy of Sciences of Ukraine, 50, Kharkivske shosse, 02160 Kyiv"
},
{
"author": "O.P. Tarasyuk",
"institution": "V.P. Kukhar Institute of Bioorganic Chemistry and Petrochemistry of the National Academy of Sciences of Ukraine, 50, Kharkivske shosse, 02160 Kyiv"
},
{
"author": "V.A. Povazhnyi",
"institution": "V.P. Kukhar Institute of Bioorganic Chemistry and Petrochemistry of the National Academy of Sciences of Ukraine, 50, Kharkivske shosse, 02160 Kyiv"
},
{
"author": "T.V. Cherniavska",
"institution": "Сhuiko Institute of Surface Chemistry of the National Academy of Sciences of Ukraine, 17, General Naumov str. 03164 Kyiv,"
},
{
"author": "S.M. Makhno",
"institution": "Сhuiko Institute of Surface Chemistry of the National Academy of Sciences of Ukraine, 17, General Naumov str. 03164 Kyiv"
}
] |
| author_sort | Rogalsky, S.P. |
| baseUrl_str | https://kataliz.org.ua/index.php/journal/oai |
| collection | OJS |
| datestamp_date | 2023-09-28T12:21:19Z |
| description | Guanidine salts are promising proton conductors due to the high content of exchangeable protons in guanidinium cation that ensure an efficient proton transfer along hydrogen-bonded network formed by proton donor and proton acceptor sites. However, the high melting point of most guanidine salts is a serious drawback for their application as proton conducting electrolytes for fuel cells. Reducing the symmetry of guanidinium cations by the substitution of hydrogen atoms on alkyl radicals reduces the melting points but also leads to decreased proton conductivity. In this study, monosubstituted guanidine salt, N-butylguanidinium bis(trifluoromethylsulfonyl)imide (BG-TFSI), has been synthesized by a simple two-step method. It is water immiscible room temperature protic ionic liquid. The structure of BG-TFSI was confirmed by nuclear magnetic resonance spectroscopy, as well as infrared spectroscopy. According to thermal gravimetric analysis data, the ionic liquid has the thermal degradation point (5% weight loss) of 348 °C which indicates its excellent thermal stability for use in high-temperature fuel cells. The ionic conductivity of BG-TFSI determined by the electrochemical impedance method was found to be 9·10-4 S/cm at room temperature. This value increased by almost one order of magnitude at temperatures above 100 °C thus reaching an acceptable level for use in fuel cells. The activation energy Ea of ionic conductivity calculated from the Arrhenius plot for BG-TFSI is 16.4 kJ/mol which is close to Ea values reported for other guanidine salts. Based on the obtained results one can assume that the proton transport in BG-TFSI is dominated by Grotthus-type (hopping) mechanism. The results of this study indicated that BG-TFSI is a promising proton conducting electrolyte for fuel cells operating at elevated temperatures in water-free conditions. The hydrophobicity of the ionic liquid is an important advantage since it can prevent its leaching from the polymer electrolyte membrane during fuel cell operation. |
| doi_str_mv | 10.15407/kataliz2021.32.086 |
| first_indexed | 2026-03-12T15:50:10Z |
| format | Article |
| fulltext |
86 Каталіз та нафтохімія, 2021, №32
ISSN 2707-5796. Kataliz ta naftohimia. 2021, 32
UDC 544.6.018.462
https://doi.org/10.15407/kataliz2021.32.086
New promising proton conducting electrolyte for high-temperature
fuel cells based on hydrophobic guanidine salt
S.P. Rogalsky1*, O.P. Tarasyuk1, V.A. Povazhnyi1, T.V. Cherniavska2, S.M. Makhno2
1 V.P. Kukhar Institute of Bioorganic Chemistry and Petrochemistry of the National Academy of Sciences of Ukraine,
50, Kharkivske shosse, 02160 Kyiv, Ukraine, sergey.rogalsky@gmail.com
2 Сhuiko Institute of Surface Chemistry of the National Academy of Sciences of Ukraine,
17, General Naumov str. 03164 Kyiv, Ukraine, stmax@ukr.net
Guanidine salts are promising proton conductors due to the high content of exchangeable protons in
guanidinium cation that ensure an efficient proton transfer along hydrogen-bonded network formed by proton donor
and proton acceptor sites. However, the high melting point of most guanidine salts is a serious drawback for their
application as proton conducting electrolytes for fuel cells. Reducing the symmetry of guanidinium cations by the
substitution of hydrogen atoms on alkyl radicals reduces the melting points but also leads to decreased proton
conductivity. In this study, monosubstituted guanidine salt, N-butylguanidinium bis(trifluoromethylsulfonyl)imide
(BG-TFSI), has been synthesized by a simple two-step method. It is water immiscible room temperature protic ionic
liquid. The structure of BG-TFSI was confirmed by nuclear magnetic resonance spectroscopy, as well as infrared
spectroscopy. According to thermal gravimetric analysis data, the ionic liquid has the thermal degradation point (5%
weight loss) of 348 °C which indicates its excellent thermal stability for use in high-temperature fuel cells. The ionic
conductivity of BG-TFSI determined by the electrochemical impedance method was found to be 9·10-4 S/cm at room
temperature. This value increased by almost one order of magnitude at temperatures above 100 °C thus reaching an
acceptable level for use in fuel cells. The activation energy Ea of ionic conductivity calculated from the Arrhenius plot
for BG-TFSI is 16.4 kJ/mol which is close to Ea values reported for other guanidine salts. Based on the obtained
results one can assume that the proton transport in BG-TFSI is dominated by Grotthus-type (hopping) mechanism.
The results of this study indicated that BG-TFSI is a promising proton conducting electrolyte for fuel cells operating
at elevated temperatures in water-free conditions. The hydrophobicity of the ionic liquid is an important advantage
since it can prevent its leaching from the polymer electrolyte membrane during fuel cell operation.
Keywords: guanidine salt, protic ionic liquid, ionic conductivity, proton conducting electrolyte
______________________________________________________________________________________________________
Introduction
Nowadays, protic ionic liquids (PILs), which are
low temperature molten salts of Brønsted acids and
Brønsted bases, are considered extremely promising
proton conducting electrolytes for fuel cell applications
[1]. A wide variety of organic amines, both aliphatic
and heterocyclic, can be used as Brønsted bases to
prepare neutral salts with strong inorganic and organic
acids such as trifluoromethanesulfonic acid,
bis(trifluoromethylsulfonyl)imide, p-toluenesulfonic
acid, dialkyl phosphate [2-6]. PILs have important
advantages such as negligible vapor pressure, thermal
stability which often exceeds 300 °C, as well as high
ionic conductivity within the range from 10-3 to 10-1
S/cm at elevated temperatures under anhydrous
conditions [1]. These compounds are being actively
studied as potential proton conducting electrolytes for
fuel cells operating above 100 °C without external
humidification [1-3, 5-7]. Hydrophobicity is a
desirable characteristic for proton conducting
electrolytes, as it prevents them from being washed out
by the water formed during fuel cell operation.
Therefore, water-immiscible PILs comprising TFSI
anion are of great interest.
Due to their polar structure, PILs have excellent
compatibility with thermally stable polymers such as
polybenzimidazole (PBI) and polyimide (PI) which are
commonly used for the fabrication of polymer-
electrolyte membranes for fuel cells [8-10]. Thus,
dense composite membranes containing more than 50
wt% of PIL were prepared, namely PBI/diethylmethyl-
ammonium trifluoromethanesulfonate (dema/ TfO) [8],
PI/1-butylimidazolium bis(trifluoromethylsulfonyl)
imide (BIM-TFSI) [9], and PI/2-butylamino-
imidazolinium bis(trifluoromethylsulfonyl)imide
(BAIM-TFSI) [10].
The most commonly used PILs contain one or
two mobile protons bound to the cation [2, 3, 7, 8]. At
mailto:sergey.rogalsky@gmail.com
mailto:stmax@ukr.net
Каталіз та нафтохімія, 2021, №32 87
ISSN 2707-5796. Kataliz ta naftohimia. 2021, 32
the same time, the high content of dissociable protons
in the PIL structure is desirable since this can facilitate
proton transfer along the hydrogen-bonded network.
Moreover, in such a case a stronger physicochemical
interaction between the ionic liquid and the polymer
matrix can be expected [10]. From this point of view,
guanidinium-based PILs seem very promising proton
conductors due to the presence of six exchangeable
protons in the cation [11, 12]. On the other hand, the
high melting point of most guanidine salts is a serious
drawback for their application as proton conducting
electrolytes. Reducing symmetry of cations can reduce
the melting points, and a series of room temperature
PILs comprising both common and cyclic guanidinium
cations and TFSI anion have been synthesized [13].
However, the substitution of hydrogen atoms on alkyl
radicals in the cation led to decreased proton
conductivity [14-16].
This research aimed to synthesize hydrophobic
guanidine salt which is liquid at room temperature.
Thus, water immiscible room temperature PIL based
on monoalkylguanidine salt has been synthesized and
studied in terms of thermal stability (TGA) and ionic
conductivity by using electrochemical impedance.
Materials and methods
Following chemicals were used for the synthesis
of ionic liquid: guanidine hydrochloride (98%),
butylamine (for synthesis) (Sigma-Aldrich), lithium
bis(trifluoromethylsulfonyl)imide (Acros), methylene
chloride (Uoslab, Ukraine).
Hydrophobic ionic liquid N-butylguanidinium bis
(trifluoromethylsulfonyl)imide (BG-TFSI) was synthe-
sized according to Scheme 1. Water soluble precursor,
N-butylguanidine hydrochloride (BG-Cl) was
synthesized using the method described in [17]. The
mixture of guanidine hydrochloride (20 g, 0.2 mol) and
butylamine (29 g, 0.4 mol) was put into a round-
bottomed flask equipped with a mechanical stirrer and
reflux condenser. The mixture was heated to 80oC and
stirred for 24 h. The residual butylamine was removed
by distillation and further in vacuum 10 mbar at 80oC.
The obtained product (BG-Cl) is viscous hazel liquid,
highly soluble in water.
7.6 g (0.05 mol) of BG-Cl were dissolved in water
(50 mL) under stirring and the solution of lithium
bis(trifluoromethylsulfonyl)imide (14.5 g, 0.05 mol) in
50 mL of water was added. The formed bottom layer
of the ionic liquid BG-TFSI was extracted with
methylene chloride (2 50 mL), washed with water
(100 mL) and dried under sodium sulfate. Methylene
chloride was distilled off, and residual solvent was
removed in vacuum 20 mbar at 70 °С for 8 h. The
viscous liquid of light yellow color was obtained.
N
H
NH
2
NH
2
NH
2
NH
2
NH
2
N
H
NH
2
NH
2
N
H
NH
2
NH
2
+
80 oC
+
_
-NH
3
+
Cl
_
(CF
3
SO
2
)
2
NLi
H
2
O, - LiCl
+
_
Cl
+_
Cl
(BG-TFSI)
(BG-Cl)
(CF
3
SO
2
)
2
N
CH
3
(CH
2
)
3
NH
2
Scheme. Synthesis of protic ionic liquid BG-TFSI.
1H NMR technique was used to characterize the
structure of BG-TFSI. 1H NMR spectra were recorded
in DMSO-d6 on a Varian Gemini-2000 (400 MHz)
spectrometer using TMS as internal standard. The
vibrational properties of ionic liquid were carried out
using a Bruker Tensor-37 FT Infrared spectrometer.
The sample was prepared as a tablet with KBr. The
spectrum was collected over the range of 400–4000
cm−1 at a resolution of 4 cm−1 in a dry atmosphere.
Thermal gravimetric analysis (TGA) was made
using a Q-1500D thermal analyzer. About 100 mg of
sample was heated from 30 oC to 1000 oC with a
heating rate of 10 °C/min in air.
The ionic conductivity was measured with the
help of impedance spectrometer Solartron SI 1260 in
the temperature range 25 – 170 °C.
Results and discussion
Figure 1 contains 1H NMR spectrum of BG-
TFSI. The triplet signal at 0.89 ppm is assigned to
methyl protons (d) of butyl radical. The sharp peaks at
1.44 and 1.31 ppm are the signals of methylene
protons (b) and (c), respectively. The sharp and
splitting peak at 3.1 ppm is assigned to protons (a) of
NCH2 group. The broadening and splitting peaks in the
region 6.5-7.8 ppm are assigned to the resonance of
guanidine protons C-NH-C, C-NH2 and C=NH2
+.
88 Каталіз та нафтохімія, 2021, №32
ISSN 2707-5796. Kataliz ta naftohimia. 2021, 32
Fig. 1. 1H NMR spectrum of BG-TFSI.
The infrared spectrum of ionic liquid BG-TFSI
(Fig. 2) is characterized by a strong absorption band
located at 1645 cm-1 and broad bands in the region
3200-3600 cm-1. The high-frequency modes are
assigned to symmetric and asymmetric bands of NH2
groups and the band at 1645 cm-1 to the scissoring
mode of the NH2 units [18]. The weak but distinct peak
observed at 2941 cm-1 is assigned to the asymmetric
stretching vibration of CH2 of disordered alkyl chains
[19]. The symmetric stretching CH2 mode expected to
be around 2875 cm-1, contributes therefore to the
broadening of the band whose maximum is located at
2881 cm-1. The bands at 2966 and 2881 cm-1 are
respectively attributed to asymmetric and symmetric
stretching vibrational modes of methyl groups. The
band at 1467 cm-1 is assigned to the bending vibrations
of CH2 groups [20]. The strong intensity bands are
located at 1658 cm-1 for the C=N stretching vibration
mode, at 1344 cm-1 and 1128 cm-1 for the SO2
antisymmetric and symmetric stretching modes and at
1186 cm-1 and 1051 cm-1 for CF3 antisymmetric
stretching and the C-C stretching modes, respectively
[21].
Fig. 2. IR spectrum of BG-TFSI.
According to TGA data, the ionic liquid has the
thermal degradation point (5% weight loss) of 348 °C,
and the maximum degradation rate is observed at
426 °C (Fig. 3, Table 1). The obtained data are similar
Каталіз та нафтохімія, 2021, №32 89
ISSN 2707-5796. Kataliz ta naftohimia. 2021, 32
to those for other reported PILs comprising TFSI anion
[2, 3, 10] and indicate sufficient thermal stability of
BG-TFSI for high temperature fuel cell applications.
100 200 300 400 500 600 700 800 900 1000
-0,5
0,0
0,5
Temperature, °С
І,
r
e
la
ti
v
e
u
n
it
s
TG
DTG
DTA
100
80
60
40
20
0
W
e
ig
h
t lo
ss, %
Fig. 3. TGA curves of BG-TFSI.
Frequency dependences of real and imaginary
components of the electrical conductivities of BG-
TFSI (Fig. 4) indicate the ionic mechanism of conduc-
tivity. At low frequencies (up to 0.1 Hz) the
conductivity of the system has the lowest value due to
the accumulation of charges on electrodes that block
the surface by a double electrical layer [22]. The
increase of ionic conductivity is observed with
increasing frequencies up to 102 Hz and the maximum
on the bottom curve indicates a decrease in the
capacitance of the electrical double layer at the
electrode. Further frequency growth leads to charge
dissipation when moved through the system [17]. The
ionic conductivity of BG-TFSI is around 10-3 S/cm at
room temperature and increases by almost one order of
magnitude at 170 °C (Fig. 5, Table 2) that indicates its
availability as a proton conducting electrolyte for high-
temperature fuel cells. It should also be noted that the
hydrophobicity of BG-TFSI is an important advantage,
since it can prevent its leaching from the polymer-
electrolyte membrane during fuel cell operation [6].
Table 1. TGA data for BG-TFSI
Sample Tm=5%, °C Tm=10%, °C Tm=20%, °C Tm=50%, °C
BG-TFSI 348 377 398 424
Fig. 4. Frequencies dependences of real (') and
imaginary ('') components of the ionic conductivity of
BG-TFSI at 20 °C.
Fig. 5. Ionic conductivity (at frequency of 1 kHz) of
BG-TFSI as a function of temperature.
Table 2. Ionic conductivity of protic ionic liquid BG-TFSI as a function of temperature
Sample
, S/cm
25°С 80°С 130°С 170°С
BG-TFSI 9.1·10-4 2.9·10-3 6.3·10-3 8·10-3
90 Каталіз та нафтохімія, 2021, №32
ISSN 2707-5796. Kataliz ta naftohimia. 2021, 32
As earlier noted, there are two types of charge
transport mechanism in PILs: vehicle (molecular
diffusion) and Grotthus-type (proton migration in the
hydrogen-bonded networks). N-butylguanidinium
cation of BG-TFSI contains five exchangeable protons
which may ensure an efficient proton hopping
conduction mechanism. The last one involves thermal
activation and follows Arrhenius law as a function of
temperature:
ln = -Ea/RT + ln0
where 0 is the maximum electrical conductivity at
infinite temperature (Scm-1), Ea is the activation
energy (kJmol-1) which indicates the energy needed
for an ion to jump to a free hole, R is the universal gas
constant (8.314 Jmol−1K−1), and T is the absolute
temperature (K).
Thus, the activation energy for ionic conducti-
vity characterizes the difficulty level of ions migration
under the electric field. In the Arrhenius diagram (Fig.
6), the dependence of ionic conductivity on tempera-
ture (ln vs 1000/T) is linear in the range from 40 to
140 oC for BG-TFSI. The activation energy Ea
calculated from the slope value (Fig. 6) is 16.4 kJ/mol.
This value is close to Ea values reported for other
guanidinium based PILs, 1-butylguanidinium tetra-
fluoroborate (Ea = 17 kJ/mol) [17] and guanidinium
nonaflate (Ea = 19 kJ/mol) [23]. Overall, the obtained
results indicate that the presence of butyl radical in
guanidinium cation does not prevent efficient proton
transfer in BG-TFSI.
Fig. 6. Arrhenius plot of ionic conductivity for BG-
TFSI
Conclusions
New hydrophobic protic ionic liquid comprising
monosubstituted guanidinium cation, N-butyl-
guanidinium bis(trifluoromethylsulfonyl)imide (BG-
TFSI), has been synthesized by a simple two-step
method. The first stage involves condensation between
guanidine hydrochloride and butylamine to prepare
water soluble precursor N-butylguanidine hydro-
chloride (BG-Cl). At the second stage, BG-Cl was
converted into the water-immiscible ionic liquid BG-
TFSI by anion exchange reaction with lithium bis
(trifluoromethylsulfonyl)imide in water solution.
According to TGA data, the ionic liquid has the
thermal degradation point (5% weight loss) of 348 °C
which indicates its sufficient thermal stability for use
in high-temperature fuel cells. The ionic conductivity
of BG-TFSI determined by the electrochemical impe-
dance method was found to be 9·10-4 S/cm at room
temperature. This value increased by almost one order
of magnitude at temperatures above 100 °C thus
reaching an acceptable level for use in fuel cells. The
activation energy Ea calculated from the Arrhenius plot
for BG-TFSI was found to be 16.4 kJ/mol which is
close to Ea values reported for other guanidinium
based ionic liquids. The obtained data also indicate
that the proton transport in BG-TFSI is dominated by
Grotthus-type (hopping) mechanism.
The liquid state of N-alkyl substituted guanidine
salt BG-TFSI is an important advantage over most
common guanidine salts which have high melting
points. Thus, room temperature PIL can provide a
satisfactory level of proton conductivity over a wide
temperature range.
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92 Каталіз та нафтохімія, 2021, №32
ISSN 2707-5796. Kataliz ta naftohimia. 2021, 32
Новий протонпровідний електроліт для високотемпературних паливних
елементів на основі гідрофобної солі гуанідину
С.П. Рогальський1*, О.П. Тарасюк1, В.А. Поважний1, Т.В. Чернявська2, С.М. Махно2
1Інститут біоорганічної хімії та нафтохімії ім. В.П. Кухаря НАН України, 50, Харківське шосе,
02160 Київ, Україна, sergey.rogalsky@gmail.com
1Інститут хімії поверхні ім. О.О. Чуйка НАН України, 17, вул. Генерала Наумова,
03164 Київ, Україна, stmax@ukr.net
Солі гуанідину є перспективними протонними провідниками завдяки високому вмісту у складі їх
катіона протонів, здатних до обміну. Це забезпечує ефективне перенесення протонів вздовж сітки водневих
зв’язків між донорними і акцепторними групами. Однак високі температури плавлення солей гуанідину є
істотним недоліком для їх використання як протонпровідних електролітів. Порушення симетрії гуанідинієвих
катіонів заміщенням водневих атомів на алкільні радикали зменшує температуру плавлення солей, а також їх
протонну провідність. У цій роботі синтезовано монозаміщену сіль гуанідину -
біс(трифторметилсульфоніл)імід N-бутилгуанідинію (БГ-ТФСІ) двостадійним методом. Сполука є протонною
іонною рідиною, яка не змішується з водою. Будову БГ-ТФСІ підтверджено методами ядерного магнітного
резонансу та інфрачервоної спектроскопії. Згідно з результатами термогравіметричного аналізу, іонна рідина
має температуру початку деструкції (втрата маси 5%) 348 °C, що свідчить про її достатню термічну стійкість
для використання у високотемпературних паливних елементах. Іонна провідність БГ-ТФСІ, визначена
методом електрохімічного імпедансу, становить 9·10-4 См/см за кімнатної температури і зростає майже на
один порядок за температур вище 100 °C. Таким чином, іонна рідина має необхідний рівень провідності для
застосуванн як електроліту в паливних елементах. Енергія активації іонної провідності Ea, визначена із
залежності Ареніуса для БГ-ТФСІ, становить 16.4 kJ/mol і є близькою до величин Ea для інших солей
гуанідину. На основі отриманих результатів можна припустити, що протонний транспорт в БГ-ТФСІ
відбувається переважно за стрибковим механізмом (Гротгуса). Результати роботи засвідчили перспективність
протонної іонної рідини БГ-ТФСІ як електроліту для паливних елементів, які функціонують за підвищених
температур і відсутності зволоження. Гідрофобність іонної рідини є важливою перевагою, оскільки може
запобігати її вимиванню з полімер-електролітної мембрани при роботі паливного елементу.
Ключові слова: сіль гуанідину, протонна іонна рідина, іонна провідність, протонпровідний електроліт
mailto:sergey.rogalsky@gmail.com
mailto:stmax@ukr.net
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| id | oai:katalizorgua:article-65 |
| institution | Catalysis and petrochemistry |
| keywords_txt_mv | keywords |
| language | English |
| last_indexed | 2026-03-12T15:50:10Z |
| publishDate | 2021 |
| publisher | V.P. Kukhar Institute of Bioorganic Chemistry and Petrochemistry of the National Academy of Sciences of Ukraine |
| record_format | ojs |
| resource_txt_mv | katalizorgua/ba/2d29a6d24fee6bff4298c6a3c40900ba.pdf |
| spelling | oai:katalizorgua:article-652023-09-28T12:21:19Z New promising proton conducting electrolyte for high-temperature fuel cells based on hydrophobic guanidine salt Новий протонпровідний електроліт для високотемпературних паливних елементів на основі гідрофобної солі гуанідину Rogalsky, S.P. Tarasyuk, O.P. Povazhnyi, V.A. Cherniavska, T.V. Makhno, S.M. guanidine salt protic ionic liquid ionic conductivity proton conducting electrolyte сіль гуанідину протонна іонна рідина іонна провідність протонпровідний електроліт Guanidine salts are promising proton conductors due to the high content of exchangeable protons in guanidinium cation that ensure an efficient proton transfer along hydrogen-bonded network formed by proton donor and proton acceptor sites. However, the high melting point of most guanidine salts is a serious drawback for their application as proton conducting electrolytes for fuel cells. Reducing the symmetry of guanidinium cations by the substitution of hydrogen atoms on alkyl radicals reduces the melting points but also leads to decreased proton conductivity. In this study, monosubstituted guanidine salt, N-butylguanidinium bis(trifluoromethylsulfonyl)imide (BG-TFSI), has been synthesized by a simple two-step method. It is water immiscible room temperature protic ionic liquid. The structure of BG-TFSI was confirmed by nuclear magnetic resonance spectroscopy, as well as infrared spectroscopy. According to thermal gravimetric analysis data, the ionic liquid has the thermal degradation point (5% weight loss) of 348 °C which indicates its excellent thermal stability for use in high-temperature fuel cells. The ionic conductivity of BG-TFSI determined by the electrochemical impedance method was found to be 9·10-4 S/cm at room temperature. This value increased by almost one order of magnitude at temperatures above 100 °C thus reaching an acceptable level for use in fuel cells. The activation energy Ea of ionic conductivity calculated from the Arrhenius plot for BG-TFSI is 16.4 kJ/mol which is close to Ea values reported for other guanidine salts. Based on the obtained results one can assume that the proton transport in BG-TFSI is dominated by Grotthus-type (hopping) mechanism. The results of this study indicated that BG-TFSI is a promising proton conducting electrolyte for fuel cells operating at elevated temperatures in water-free conditions. The hydrophobicity of the ionic liquid is an important advantage since it can prevent its leaching from the polymer electrolyte membrane during fuel cell operation. Солі гуанідину є перспективними протонними провідниками завдяки високому вмісту у складі їх катіона протонів, здатних до обміну. Це забезпечує ефективне перенесення протонів вздовж сітки водневих зв’язків між донорними і акцепторними групами. Однак високі температури плавлення солей гуанідину є істотним недоліком для їх використання як протонпровідних електролітів. Порушення симетрії гуанідинієвих катіонів заміщенням водневих атомів на алкільні радикали зменшує температуру плавлення солей, а також їх протонну провідність. У цій роботі синтезовано монозаміщену сіль гуанідину-біс(трифторметилсульфоніл)імід N-бутилгуанідинію (БГ-ТФСІ) двостадійним методом. Сполука є протонною іонною рідиною, яка не змішується з водою. Будову БГ-ТФСІ підтверджено методами ядерного магнітного резонансу та інфрачервоної спектроскопії. Згідно з результатами термогравіметричного аналізу, іонна рідина має температуру початку деструкції (втрата маси 5%) 348 °C, що свідчить про її достатню термічну стійкість для використання у високотемпературних паливних елементах. Іонна провідність БГ-ТФСІ, визначена методом електрохімічного імпедансу, становить 9·10-4 См/см за кімнатної температури і зростає майже на один порядок за температур вище 100 °C. Таким чином, іонна рідина має необхідний рівень провідності для застосуванн як електроліту в паливних елементах. Енергія активації іонної провідності Ea, визначена із залежності Ареніуса для БГ-ТФСІ, становить 16.4 kJ/mol і є близькою до величин Ea для інших солей гуанідину. На основі отриманих результатів можна припустити, що протонний транспорт в БГ-ТФСІ відбувається переважно за стрибковим механізмом (Гротгуса). Результати роботи засвідчили перспективність протонної іонної рідини БГ-ТФСІ як електроліту для паливних елементів, які функціонують за підвищених температур і відсутності зволоження. Гідрофобність іонної рідини є важливою перевагою, оскільки може запобігати її вимиванню з полімер-електролітної мембрани при роботі паливного елементу. V.P. Kukhar Institute of Bioorganic Chemistry and Petrochemistry of the National Academy of Sciences of Ukraine 2021-12-28 Article Article application/pdf https://kataliz.org.ua/index.php/journal/article/view/65 10.15407/kataliz2021.32.086 Catalysis and petrochemistry; No. 32 (2021): Catalysis and petrochemistry; 86-92 Каталіз та нафтохімія; № 32 (2021): Каталіз та нафтохімія; 86-92 2707-5796 2412-4176 10.15407/kataliz2021.32 en https://kataliz.org.ua/index.php/journal/article/view/65/55 Copyright (c) 2021 Catalysis and petrochemistry |
| spellingShingle | сіль гуанідину протонна іонна рідина іонна провідність протонпровідний електроліт Rogalsky, S.P. Tarasyuk, O.P. Povazhnyi, V.A. Cherniavska, T.V. Makhno, S.M. Новий протонпровідний електроліт для високотемпературних паливних елементів на основі гідрофобної солі гуанідину |
| title | Новий протонпровідний електроліт для високотемпературних паливних елементів на основі гідрофобної солі гуанідину |
| title_alt | New promising proton conducting electrolyte for high-temperature fuel cells based on hydrophobic guanidine salt |
| title_full | Новий протонпровідний електроліт для високотемпературних паливних елементів на основі гідрофобної солі гуанідину |
| title_fullStr | Новий протонпровідний електроліт для високотемпературних паливних елементів на основі гідрофобної солі гуанідину |
| title_full_unstemmed | Новий протонпровідний електроліт для високотемпературних паливних елементів на основі гідрофобної солі гуанідину |
| title_short | Новий протонпровідний електроліт для високотемпературних паливних елементів на основі гідрофобної солі гуанідину |
| title_sort | новий протонпровідний електроліт для високотемпературних паливних елементів на основі гідрофобної солі гуанідину |
| topic | сіль гуанідину протонна іонна рідина іонна провідність протонпровідний електроліт |
| topic_facet | guanidine salt protic ionic liquid ionic conductivity proton conducting electrolyte сіль гуанідину протонна іонна рідина іонна провідність протонпровідний електроліт |
| url | https://kataliz.org.ua/index.php/journal/article/view/65 |
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