JP2018142491A - Proton conducting electrolyte and fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a proton conductive electrolyte that can be used even at 100° C. or higher and without humidification, and a fuel cell provided with this proton conductive electrolyte. A proton-conducting electrolyte containing a compound having a temperature range of a plastic crystal in a temperature range of 100° C. or higher. The compound is a proton conductive electrolyte containing an anion having a cyclic sulfonylimide skeleton represented by formula (I). Alternatively, the compound is a proton-conducting electrolyte having a cyclic or chain-like tertiary amino group having an amino group and containing a cation to which a proton has been added. [Selection diagram] None

Description

  The present invention relates to a proton conductive electrolyte and a fuel cell.

  Fuel cells are classified into several types depending on the type of electrolyte. Among these, solid polymer fuel cells (PEFC) using a polymer membrane having ion conductivity (ion exchange membrane) as the electrolyte can be reduced in size and weight. Therefore, it is expected to be applied to portable devices, fuel cell vehicles and the like.

  PEFC generates electricity by sandwiching an ion exchange membrane as an electrolyte between a positive electrode and a negative electrode, supplying oxygen to the positive electrode, and supplying a fuel such as hydrogen to the negative electrode. As an electrolyte of PEFC, for example, a perfluoroalkyl sulfonic acid polymer (for example, Nafion (registered trademark)) membrane or the like is used.

  A PEFC using a fluorocarbon ion exchange membrane such as a perfluoroalkylsulfonic acid polymer membrane is operated in a relatively low temperature range of about 80 ° C. This is because the ion exchange membrane needs to be sufficiently humidified in order to improve proton conductivity, the operating temperature is limited to less than the boiling point of water, and the heat resistance of the ion exchange membrane is low. It is done.

  On the other hand, in recent years, various advantages by increasing the operating temperature of PEFC have been reported. Advantages of increasing the operating temperature of PEFC include the ability to reduce the amount of platinum and other catalysts used by improving power generation efficiency and the reduction of CO poisoning in platinum and other catalysts. For example, the system can be simplified (see, for example, Patent Document 1). Thus, there is an increasing expectation for PEFC that can operate in a medium temperature range of about 100 ° C to 200 ° C. For example, a conductive membrane that can be used at 100 ° C. or higher and without humidification, and a fuel cell using the conductive membrane as an electrolyte have been proposed (for example, see Patent Documents 1 and 2).

JP 2004-185891 A Japanese Patent Laid-Open No. 2006-4621

  As described above, development of a new proton-conducting electrolyte that can be used at 100 ° C. or higher and without humidification is demanded from the viewpoint of improving power generation efficiency and simplifying the system.

  An object of one embodiment of the present invention is to provide a proton conductive electrolyte that can be used at 100 ° C. or higher and without humidification, and a fuel cell including the proton conductive electrolyte.

Means for solving the above problems include the following aspects.
<1> A proton conductive electrolyte containing a compound having a temperature region that becomes a plastic crystal in a temperature region of 100 ° C. or higher.
<2> The proton conductive electrolyte according to <1>, wherein the compound includes an anion having a cyclic sulfonylimide skeleton.
<3> The proton conductive electrolyte according to <1> or <2>, wherein the compound includes an anion having a cyclic perfluoroalkylsulfonylimide skeleton.
<4> The proton conductive electrolyte according to <2>, wherein the anion having a cyclic sulfonylimide skeleton is an anion represented by the following chemical formula (I).

<5> The proton conductive electrolyte according to any one of <1> to <4>, wherein the compound includes a cation having an amino group.
<6> The proton conductive electrolyte according to any one of <1> to <5>, wherein the compound includes an amino group and includes a cation provided with a proton.
<7> The proton conduction according to <6>, wherein the cation having an amino group and imparted with a proton is at least one selected from cations imparted with a proton to a compound represented by the following chemical formula: Electrolyte.

<8> The proton conductive electrolyte according to any one of <1> to <7>, further including at least one of a proton donating compound and a proton coordination compound.

<9> A fuel cell comprising the proton conductive electrolyte according to any one of <1> to <8>.

  According to one aspect of the present invention, a proton conductive electrolyte that can be used at 100 ° C. or higher and without humidification, a compound used to form the proton conductive electrolyte, and a fuel cell including the proton conductive electrolyte are provided. Can do.

2 is a graph showing the results of differential scanning calorimetry (DSC) in Example 1. 4 is a graph showing the results of ionic conductivity in Example 1. It is a graph which shows the result of differential scanning calorimetry (DSC) in Example 2. It is a graph which shows the result of the ionic conductivity in Example 2. 6 is a graph showing the results of differential scanning calorimetry (DSC) in Example 3. It is a graph which shows the result of the ionic conductivity in Example 3. It is a graph which shows the result of differential scanning calorimetry (DSC) in Example 4. It is a graph which shows the result of the ionic conductivity in Example 4. 10 is a graph showing the results of differential scanning calorimetry (DSC) in Example 5. It is a graph which shows the result of differential scanning calorimetry (DSC) in Example 6. It is a graph which shows the result of differential scanning calorimetry (DSC) in Example 7. 10 is a graph showing the results of differential scanning calorimetry (DSC) in Example 8. It is a graph which shows the result of differential scanning calorimetry (DSC) in Example 9. It is a graph which shows the result of differential scanning calorimetry (DSC) in Example 10. 14 is a graph showing the results of differential scanning calorimetry (DSC) in Example 11. It is a graph which shows the result of differential scanning calorimetry (DSC) in Example 12. It is a graph which shows the result of differential scanning calorimetry (DSC) in Example 13. It is a graph which shows the result of differential scanning calorimetry (DSC) in Example 14. It is a graph which shows the result of differential scanning calorimetry (DSC) in Example 15. It is a graph which shows the result of the differential scanning calorimetry (DSC) in Example 16. It is a graph which shows the result of the differential scanning calorimetry (DSC) in Example 17 (no proton donating compound dope). It is a graph which shows the result of the ionic conductivity in Example 17 (no proton donating compound dope). It is a graph which shows the result of the differential scanning calorimetry (DSC) in Example 18 (with proton donating compound dope). It is a graph which shows the result of the ionic conductivity in Example 18 (with proton donating compound dope).

Hereinafter, the present disclosure will be described in detail.
In the present disclosure, the numerical ranges indicated by using “to” include numerical values described before and after “to” as the minimum value and the maximum value, respectively.

  The proton conductive electrolyte of the present disclosure includes a compound having a temperature range that becomes a plastic crystal in a temperature range of 100 ° C. or higher (hereinafter also referred to as “compound of the present disclosure”).

  In general, a plastic crystal is an intermediate state between a crystal and a liquid. In detail, plastic crystal is a solid state in which regularity is seen in the three-dimensional arrangement of molecules or ions constituting it, but there is no regularity in the orientation of molecules or ions as in the liquid state. Molecules or ions exhibiting plastic crystallinity can also rotate. In the plastic crystal, proton conduction occurs by a mechanism (Grotus mechanism) in which target ions, for example, protons hop between molecules. Therefore, in the proton conductive electrolyte of the present disclosure, the proton conductive electrolyte includes a compound having a temperature region that becomes a plastic crystal in a temperature region that becomes a plastic crystal, and that has a temperature region that becomes a plastic crystal in a temperature region of 100 ° C. or higher. By using the fuel cell, the fuel cell can operate in a temperature range of 100 ° C. or higher.

  Further, in a normal polymer electrolyte fuel cell (PEFC), proton conduction occurs due to a mechanism (vehicle mechanism) in which oxonium ions in which protons are bonded to water molecules move in the electrolyte. Therefore, humidification of the electrolyte is necessary for proton conduction.

  On the other hand, in the fuel cell using the proton conductive electrolyte of the present disclosure, as described above, proton conduction occurs due to a mechanism in which protons hop between molecules (Grotus mechanism), and thus high proton conductivity without humidification. Can be obtained. Therefore, by using the proton conductive electrolyte of the present disclosure, the fuel cell can operate without being humidified in a temperature range of 100 ° C. or higher.

In the present disclosure, a compound that exhibits a peak corresponding to a phase transition between solid phases that becomes a plastic crystal by differential scanning calorimetry (DSC) is referred to as a “compound that becomes a plastic crystal”.
In the present disclosure, the “temperature range in which a plastic crystal is formed” refers to a first peak corresponding to a phase transition between solid phases that forms a plastic crystal when the temperature is raised, and a first peak in differential scanning calorimetry (DSC). Indicates a temperature region between the temperature showing the first peak and the temperature showing the second peak, when it has a second peak corresponding to the melting point at a temperature higher than the temperature obtained.
Therefore, “having a temperature region in which a plastic crystal is formed in a temperature region of 100 ° C. or higher” indicates that the second peak is 100 ° C. or higher when the first peak and the second peak are included. In addition, the compound which has the temperature range which becomes a plastic crystal in the temperature range of 100 degreeC or more may have the temperature range which becomes a plastic crystal in the temperature range below 100 degreeC, and does not need to have it. .
Moreover, when the compound of this indication is decomposed | disassembled before melting | dissolving, let the temperature range between the temperature which shows a 1st peak, and the temperature which a compound decomposes | disassemble be "the temperature range which becomes a plastic crystal."

  In the compound of the present disclosure, the temperature range for forming a plastic crystal is not particularly limited as long as it is 100 ° C. or higher, and may be, for example, 100 ° C. to 400 ° C. or 120 ° C. to 350 ° C. .

  The compound of the present disclosure preferably includes an anion having a cyclic sulfonylimide skeleton. Inclusion of an anion having a cyclic sulfonylimide skeleton as a counter ion tends to allow an increase in melting point by limiting molecular motion compared to a compound containing an anion having a chain sulfonylimide skeleton as a counter ion. There is a tendency that the temperature region in which the plastic crystal of the compound of the present disclosure becomes a plastic crystal can be shifted to higher temperatures. Furthermore, since a high degree of dissociation derived from the sulfonylimide skeleton can be obtained, proton conductivity tends to be improved.

An anion having a cyclic sulfonylimide skeleton refers to an anion having a “—S (═O) ₂ —N ^— S (═O) ₂ —” skeleton in the ring structure. The ring structure is preferably a 4-membered ring to an 8-membered ring, more preferably a 5-membered ring to a 7-membered ring, and even more preferably a 6-membered ring.

  The compound of the present disclosure preferably includes an anion having a cyclic perfluoroalkylsulfonylimide skeleton. By including an anion having a cyclic perfluoroalkylsulfonylimide skeleton as a counter ion, the compound having an anion having a chain perfluorosulfonylimide skeleton (for example, a bis (trifluoromethanesulfonyl) imide anion) as a counter ion. By limiting the molecular motion, the melting point tends to be increased, and the temperature range that becomes the plastic crystal of the compound of the present disclosure tends to be shifted to a higher temperature.

The anion having a cyclic perfluoroalkylsulfonylimide skeleton refers to an anion having a “—S (═O) ₂ —N ^— S (═O) ₂ —” skeleton and a perfluoroalkynyl group in the ring structure. Further, both ends of the “—S (═O) ₂ —N ^— S (═O) ₂ —” skeleton are respectively bonded to both ends of the perfluoroalkynyl group to form a ring structure. Also good. The ring structure is preferably a 4-membered ring to an 8-membered ring, more preferably a 5-membered ring to a 7-membered ring, and even more preferably a 6-membered ring. Examples of the anion having a 6-membered cyclic perfluoroalkylsulfonylimide skeleton include anions represented by the following chemical formula (I).

  The fluorine atom in the perfluoroalkynyl group may be substituted with another atom or a functional group such as an alkyl group.

The compound of the present disclosure preferably includes a cation having an amino group. Examples of the amino group include a primary amino group, a secondary amino group, a tertiary amino group, and a quaternary amino group.
The cation having an amino group is not particularly limited, and may be a cation derived from a chain amine or a cation derived from a cyclic amine. When the cation having an amino group is a cation derived from a cyclic amine, the cyclic amine may have an amino group in the ring structure, or may have an amino group branched from the ring structure. Good. In addition, the cation having an amino group may have one amino group or a plurality of amino groups.

  Examples of the cation having an amino group include an amine cation and an ammonium cation. The cation having an amino group may be a cation having an amino group and a proton.

  The chain amine may be a linear or branched amine, and is a compound in which the nitrogen atom in the chain amine is bonded to one to four hydrocarbon groups having 1 to 10 carbon atoms. Is preferable, and a compound having 1 to 3 bonds is more preferable. The chain amine may have one amino group in the molecule or a plurality of amino groups.

  As the cyclic amine, a compound having one or more amino groups in the ring structure and having a ring structure of 5 to 9 members is preferable. The hydrogen atom in the ring structure may be substituted with another atom or a functional group such as an alkyl group.

  The cyclic amine is more preferably a compound having an amino group in the ring structure and a ring structure of any of a 5-membered ring, a 7-membered ring and an 8-membered ring from the viewpoint of improving proton conductivity. More preferably, the compound has an amino group in the ring structure and the ring structure is a 5-membered ring.

  The cation having an amino group and imparted with a proton is preferably at least one selected from cations imparted with a proton to a compound represented by the following chemical formula.

  In addition, the compound of the present disclosure may be a compound including a cation having an amino group and having a proton attached thereto, and an anion having the above-described cyclic sulfonylimide skeleton. The compound containing the provided cation and the anion which has a cyclic | annular perfluoroalkyl sulfonylimide skeleton may be sufficient.

  The compound of the present disclosure is obtained by reacting, for example, a halogen salt of a cation having an amino group (preferably an ammonium cation) and an anion salt having a cyclic sulfonylimide skeleton (lithium salt, sodium salt, potassium salt, etc.). Can be synthesized.

  In addition, the proton conductive electrolyte of the present disclosure preferably further includes at least one of a proton donating compound and a proton coordination compound. This tends to improve the proton conductivity of the proton conductive electrolyte.

  The proton donating compound is not particularly limited as long as it imparts protons to other compounds, and examples thereof include inorganic or organic proton donating compounds (for example, inorganic or organic proton acids). Examples of inorganic proton donating compounds include hydrochloric acid, sulfuric acid, boric acid, nitric acid, phosphoric acid, perchloric acid, and the like. Examples of organic proton donating compounds include formic acid, acetic acid, propionic acid, oxalic acid, benzoic acid, acrylic acid, methacrylic acid, itaconic acid, phthalic acid, maleic acid, benzenesulfonic acid, o, m, and p-toluene. Examples include sulfonic acid, methanesulfonic acid, trifluoromethanesulfonic acid, nonafluoro-1-butanesulfonic acid, heptadecafluorooctanesulfonic acid, bis (trifluoromethane) sulfnimide (HTFSI), trifluoroacetic acid, imidazole, benzimidazole, and triazole. It is done. Further, the proton donating compound may be a compound represented by the following chemical formula (II).

  The proton-coordinating compound is not particularly limited as long as it has a coordination point for coordinating protons in the molecule. For example, aliphatic amines, imidazoles, triazoles, benzimidazoles, benzotriazoles, these Derivatives and the like.

  For example, for a cation having an amino group contained in the compound of the present disclosure, when the amino group is a quaternary amino group, the proton conductive electrolyte of the present disclosure further improves the proton donating compound from the viewpoint of increasing proton conductivity. It is preferable to include.

  In the proton conductive electrolyte of the present disclosure, the content of at least one of the proton donating compound and the proton coordination compound is not particularly limited, and is 0.01 mol to 0.3 mol with respect to 1 mol of the compound of the present disclosure. The molar ratio is preferably 0.05 mol, more preferably 0.05 mol to 0.2 mol, and still more preferably 0.08 mol to 0.15 mol.

<Fuel cell>
The fuel cell according to the present disclosure includes the proton conductive electrolyte described above. Accordingly, a fuel cell that can operate even at 100 ° C. or higher and without humidification, and more specifically, has a temperature range that can operate at 100 ° C. or higher and that can operate without humidification in the temperature range is provided. can do.

  Since the fuel cell of the present disclosure can be operated at 100 ° C. or higher, it has excellent power generation efficiency and can reduce the amount of catalyst such as platinum. This reduces the cost of the fuel cell. In addition, since the fuel cell of the present disclosure can operate at a higher temperature than a normal solid polymer fuel cell, higher-temperature exhaust heat is generated, and the exhaust heat can be effectively used.

  Furthermore, by operating the fuel cell at 100 ° C. or higher, CO poisoning in a catalyst such as platinum can be reduced, and CO removal is unnecessary or the burden of CO removal is reduced. This eliminates the need for a CO converter and a CO remover in a fuel cell system including a fuel reformer, or reduces these burdens, and simplifies the system configuration.

  The fuel cell of the present disclosure may be incorporated in a portable device, a fuel cell vehicle, or the like.

  Hereinafter, the present disclosure will be described in detail by way of examples, but the present disclosure is not limited thereto. In the graph showing the DSC results in each figure, the horizontal axis represents temperature (° C.).

[Example 1]
First, a compound having an amino group and a compound represented by the above-mentioned chemical formula (II) are mixed and reacted to obtain a compound containing a cation having an amino group and an anion represented by the above-mentioned chemical formula (I). Obtained. Pyrrolidine was used as the compound having an amino group.

  Next, for the obtained compound, after recrystallization, the temperature at which the interphase transition occurs and the melting point were determined by differential scanning calorimetry (DSC). Specifically, using a differential scanning calorimeter (manufactured by Shimadzu Corporation, DSC-60), the measurement was performed at a heating rate of 10 ° C. per minute. The results are shown in FIG.

As shown in FIG. 1 and Table 1, peaks corresponding to the phase transition between solid phases were observed at −61.7 ° C. and 142.5 ° C., and peaks corresponding to the melting point were observed at 199.9 ° C. . The melting entropy was 13.97 J / mol K.
Thereby, about the compound obtained in Example 1, it confirmed that 142.5 degreeC-199.9 degreeC was a temperature range used as a plastic crystal.

Moreover, about the obtained compound, it heat-processed at 180 degreeC for 4.5 hours, and measured ion conductivity (Conductivity (Scm < ^-1 >)). Ion conductivity was measured in an argon atmosphere in order to eliminate the influence of water vapor. The ion conductivity was measured after confirming that the resistance value was constant, and a metal plate was used for all measurements.
The results are shown in FIG.
In addition, the sample after the measurement was discolored black.

As shown in FIG. 2, the ionic conductivity increases with increasing temperature (decreasing 1000 / T) from around 1000 / T (K ⁻¹ ) exceeding 2.4 (near the temperature region where the plastic crystal is formed). An upward trend was confirmed. Thereby, when the temperature range which becomes a plastic crystal exists in the temperature range of 100 degreeC or more, it was shown that ion conductivity increases in the temperature range.

[Example 2]
A compound containing a cation having an amino group and an anion represented by the above-mentioned chemical formula (I) was obtained in the same manner as in Example 1 except that piperidine was used as the compound having an amino group.

Next, for the obtained compound, after recrystallization, the temperature at which the interphase transition occurs and the melting point were determined by differential scanning calorimetry (DSC) in the same manner as in Example 1.
The results are shown in FIG.

As shown in FIG. 3 and Table 1, peaks corresponding to the phase transition between solid phases were observed at about 31 ° C. and 143.9 ° C., and a peak corresponding to the melting point was observed at 216.2 ° C. The melting entropy was 15.7 J / mol K.
Thereby, about the compound obtained in Example 2, it was confirmed that 143.9 degreeC-216.2 degreeC is a temperature range used as a plastic crystal.

Further, the obtained compound was heat-treated at 200 ° C. for 26 hours, and the ionic conductivity was measured in the same manner as in Example 1.
The results are shown in FIG.
There was no particular change in the sample after measurement.

As shown in FIG. 4, it was confirmed that 1000 / T (K ⁻¹ ) tends to increase significantly with increasing temperature from around 2.4 (near the temperature region where the plastic crystal is formed). Thereby, when the temperature range which becomes a plastic crystal exists in the temperature range of 100 degreeC or more, it was shown that ion conductivity increases in the temperature range.

[Example 3]
Except having used hexamethyleneimine as a compound which has an amino group, it carried out similarly to Example 1, and obtained the compound containing the cation which has an amino group, and the anion represented by the above-mentioned chemical formula (I).

Next, for the obtained compound, after recrystallization, the temperature at which the interphase transition occurs and the melting point were determined by differential scanning calorimetry (DSC) in the same manner as in Example 1.
The results are shown in FIG.

As shown in FIG. 5 and Table 1, a peak corresponding to the interphase transition was observed at 137.1 ° C., and a peak corresponding to the melting point was observed at 193.7 ° C. The melting entropy was 14.7 J / mol K.
Thereby, about the compound obtained in Example 3, it was confirmed that 137.1 degreeC-193.7 degreeC is a temperature range used as a plastic crystal.

Further, the obtained compound was heat-treated at 170 ° C. for about 23 hours, and then the ionic conductivity was measured in the same manner as in Example 1.
The results are shown in FIG.
In addition, a part of the sample after the measurement was dark.

As shown in FIG. 6, the ionic conductivity tends to increase greatly as the temperature increases from about 1000 / T (K ⁻¹ ) between 2.4 and 2.5 (near the temperature range where the plastic crystal is formed). confirmed. Thereby, when the temperature range which becomes a plastic crystal exists in the temperature range of 100 degreeC or more, it was shown that ion conductivity increases in the temperature range.

[Example 4]
Except having used heptamethyleneimine as a compound which has an amino group, it carried out similarly to Example 1, and obtained the compound containing the cation which has an amino group, and the anion represented by the above-mentioned chemical formula (I).

Next, for the obtained compound, after recrystallization, the temperature at which the interphase transition occurs and the melting point were determined by differential scanning calorimetry (DSC) in the same manner as in Example 1.
The results are shown in FIG.

As shown in FIG. 7 and Table 1, peaks corresponding to the phase transition between solid phases were observed at 134.5 ° C. and 144.3 ° C., and a peak corresponding to the melting point was observed at 177.7 ° C. The melting entropy was 11.2 J / mol K.
Thereby, about the compound obtained in Example 4, it was confirmed that 144.3 degreeC-177.7 degreeC is a temperature range used as a plastic crystal.

Further, the obtained compound was heat-treated at 160 ° C. for 12 hours, and then ion conductivity was measured in the same manner as in Example 1.
The results are shown in FIG.
There was no particular change in the sample after measurement.

As shown in FIG. 8, it is confirmed that the ionic conductivity tends to increase greatly as the temperature rises from 1000 / T (K ⁻¹ ) between 2.4 and 2.5 (near the temperature range where the plastic crystal is formed). It was done. Thereby, when the temperature range which becomes a plastic crystal exists in the temperature range of 100 degreeC or more, it was shown that ion conductivity increases in the temperature range.

[Examples 5 to 16]
Except having used the compound shown in Table 1 as a compound which has an amino group, it carried out similarly to Example 1, and obtained the compound containing the cation which has an amino group, and the anion represented by the above-mentioned chemical formula (I).

Next, with respect to the compounds obtained in Examples 5 to 16, in the same manner as in Example 1, differential scanning calorimetry (DSC) was performed to determine the temperature at which interphase transition occurs and the melting point. Examples 5 to 7 and Example 14 perform differential scanning calorimetry (DSC) after recrystallization, and Examples 8 to 13 and Examples 15 and 16 perform differential scanning calorimetry (DSC) after synthesis. It was.
The results are shown in FIGS. 9 to 20 and Table 1. In Table 1, “-” indicates that there is no data.

As shown in Table 1 and FIGS. 9-20, about the compound containing the cation which has an amino group in Example 5- Example 16, and the anion represented by the above-mentioned chemical formula (I), it is soft at 100 degreeC or more. It was confirmed that there was a temperature region that became viscous crystals and did not melt.
As shown in FIG. 13, in Example 8, the melting point did not appear in the DSC curve, but it was found that the measurement sample was dark at around 300 ° C. In Example 8, it is presumed that the temperature from decomposition at a temperature of 95.5 ° C. at which a peak corresponding to the phase transition between solid phases is observed is a temperature range in which a plastic crystal is formed.

[Examples 17 and 18]
Next, a compound containing a pyrrolidine cation and the anion represented by the above chemical formula (I) was synthesized in the same manner as in Example 2, and the ion conductivity when this compound was doped with a proton donating compound was synthesized. The impact was examined.
First, as Example 17, a compound containing a pyrrolidine cation and the anion represented by the above chemical formula (I) (without proton donating compound dope) was prepared. As Example 18, the pyrrolidine cation and the above chemical formula ( A compound (with proton donating compound dope) containing an anion represented by I) was prepared. About Example 18, 0.1 mol dope with respect to 1 mol of compounds which synthesize | combined the compound represented by the above-mentioned chemical formula (II).

Next, the temperature and melting point at which the interphase transition occurred were determined by differential scanning calorimetry (DSC) in the same manner as in Example 1 for the obtained compound.
The results are shown in FIGS.

As shown in FIG. 21, in Example 17, peaks corresponding to the interphase transition were observed at 31 to 34 ° C. and 148.0 ° C., and peaks corresponding to the melting point were observed at 216.8 ° C. It was.
Moreover, as shown in FIG. 23, in Example 18, the peaks corresponding to the phase transition between the solid phases were observed at 31 to 34 ° C. and 145.0 ° C., and the peak corresponding to the melting point was at 209.8 ° C. Observed.

Moreover, about the obtained compound, after heat-processing at 200 degreeC for 16 hours 45 minutes, ion conductivity (Conductivity (Scm < ^-1 >)) was measured. Ion conductivity was measured in an argon atmosphere in order to eliminate the influence of water vapor. The ion conductivity was measured after confirming that the resistance value was constant, and a metal plate was used for all measurements.
The results are shown in FIGS.

  As shown in FIGS. 22 and 24, it was confirmed that doping the proton donating compound improves the ion conductivity as compared with the case where the proton donating compound is not doped.

[Example 19]
A compound containing an amino group represented by the chemical formula [N (CH ₂ CH ₃ ) ₃ CH ₃ ] ⁺ X ⁻ (X is a chlorine atom) and a lithium salt of an anion represented by the above chemical formula (I) To obtain a compound containing a cation having an amino group represented by the chemical formula [N (CH ₂ CH ₃ ) ₃ CH ₃ ] ⁺ and an anion represented by the chemical formula (I).

Next, for the obtained compound, after recrystallization, the temperature at which the interphase transition occurs and the melting point were determined by differential scanning calorimetry (DSC) in the same manner as in Example 1.
A peak corresponding to the interphase transition was observed at −28.2 ° C., and a peak corresponding to the melting point was observed at 268.3 ° C. The melting entropy was 7.4 J / mol K.
Thereby, about the compound obtained in Example 19, it was confirmed that -28.2 degreeC-268.3 degreeC is a temperature range used as a plastic crystal.
In addition, about the compound obtained in Example 19, it is preferable to dope a proton-donating compound from the point which improves proton conductivity.

[Comparative Example 1]
A compound having an amino group represented by the chemical formula [N (CH ₂ CH ₃ ) ₃ CH ₃ ] ⁺ Cl ⁻ is reacted with a compound containing a lithium salt of an anion represented by the following chemical formula (III). A compound containing a cation having an amino group represented by N (CH ₂ CH ₃ ) ₃ CH ₃ ] ⁺ and an anion represented by the following chemical formula (III) was obtained.

Next, for the obtained compound, after recrystallization, the temperature at which the interphase transition occurs and the melting point were determined by differential scanning calorimetry (DSC) in the same manner as in Example 1.
A peak corresponding to the phase transition between solid phases was observed at −51.7 ° C., and a peak corresponding to the melting point was observed at 95.6 ° C. The melting entropy was 7.6 J / mol K.
Thereby, about the compound obtained by the comparative example 1, -51.7 degreeC-95.6 degreeC is a temperature range used as a plastic crystal, and confirms that the temperature range used as a plastic crystal is less than 100 degreeC. did.

[Comparative Example 1]
A cation chloride having an amino group represented by the following chemical formula (IV) is reacted with a compound containing a lithium salt of an anion represented by the above chemical formula (III), and represented by the following chemical formula (IV). A compound containing a cation having an amino group and an anion represented by the chemical formula (III) was obtained.

Next, for the obtained compound, after recrystallization, the temperature at which the interphase transition occurs and the melting point were determined by differential scanning calorimetry (DSC) in the same manner as in Example 1.
A peak corresponding to the interphase transition was observed at −14 ° C., and a peak corresponding to the melting point was observed at 86 ° C.
Thereby, about the compound obtained by the comparative example 2, it was confirmed that -14 degreeC-86 degreeC is a temperature range used as a plastic crystal, and the temperature range used as a plastic crystal is less than 100 degreeC.

Claims (9)

  A proton-conducting electrolyte comprising a compound having a temperature region that becomes a plastic crystal in a temperature region of 100 ° C. or higher.   The proton conductive electrolyte according to claim 1, wherein the compound contains an anion having a cyclic sulfonylimide skeleton.   The proton conductive electrolyte according to claim 1, wherein the compound contains an anion having a cyclic perfluoroalkylsulfonylimide skeleton. The proton conductive electrolyte according to claim 2, wherein the anion having the cyclic sulfonylimide skeleton is an anion represented by the following chemical formula (I).
  The proton conductive electrolyte according to any one of claims 1 to 4, wherein the compound includes a cation having an amino group.   The proton conductive electrolyte according to any one of claims 1 to 5, wherein the compound includes an amino group and a cation to which a proton is imparted. The proton-conducting electrolyte according to claim 6, wherein the cation having an amino group and imparted with a proton is at least one selected from cations imparted with a proton in a compound represented by the following chemical formula.
  The proton conductive electrolyte according to any one of claims 1 to 7, further comprising at least one of a proton donating compound and a proton coordination compound.   A fuel cell comprising the proton conductive electrolyte according to any one of claims 1 to 8.