JP6369940B2 - Ion conductive composite - Google Patents

Description

  The present invention relates to an ion conductive composite that is a composite of a porous coordination polymer having pores and an ionic liquid, and functions as an electrolyte of an electrochemical device that can operate safely and in a wide temperature range, for example. The present invention relates to an ion conductive composite.

  It has been proposed that ionic liquids are used in electrochemical devices as electrolytes for batteries, electric double layer capacitors and the like because of their high ion conductivity. Since the ionic liquid has extremely high flame retardancy, when it is used as an electrolyte of an electrochemical device, an flammable organic solvent is not required, and an electrochemical device having high safety can be obtained.

  An ionic liquid generally refers to a salt having a melting point of 100 ° C. or lower. An ionic liquid has a higher melting point than an organic solvent, and it often solidifies at room temperature and does not function as an electrolyte for an electrochemical device. In order to allow such an ionic liquid to function as an electrolyte even at room temperature or lower, a method for reducing the melting point of the ionic liquid by filling or injecting the ionic liquid into the nanopores of the porous glass has been proposed (for example, Patent Document 1). Furthermore, a correlation between the size of the nanopore and the melting point of the filled ionic liquid has also been reported (for example, see Non-Patent Document 1).

  By the way, the present applicant has disclosed a patent document 2 in which a porous coordination polymer is filled with an ionic liquid as a material having micropores smaller in size than nanopores, and the melting point is greatly reduced. The porous coordination polymer-ionic liquid composite described in 1) was developed previously.

  However, the porous coordination polymer described in Patent Document 2 generally has a small pore size of 20 mm or less. Further, the diameter of the entrance / exit of the pore is generally 10 mm or less. Therefore, when filling the pores of such a porous coordination polymer with an ionic liquid, the rate at which the ionic liquid diffuses in the pores of the porous coordination polymer is extremely slow. For this reason, the composite described in Patent Document 2 has a problem that the filling rate of the ionic liquid into the porous coordination polymer is lowered, and the ionic conductivity when used as an electrolyte is lowered.

  As a means for improving the filling rate of the ionic liquid, it is conceivable to promote the diffusion of the ionic liquid by mixing the porous coordination polymer and the ionic liquid and then holding the mixture at a high temperature for a long time. However, there is a problem that the porous coordination polymer is gradually decomposed by keeping the temperature high for a long time. When the porous coordination polymer is decomposed, the pores are crushed, so that the melting point is not lowered, or the ionic conductivity is lowered. In addition, since the constituent components of the porous coordination polymer are mixed into the electrolyte as impurities, problems such as metal deposition, gas generation, and deterioration in cycle characteristics have occurred when incorporated into an electrochemical device.

JP 2006-281105 A International Publication No. 2013/161452

M. Kanakubo et.al., Chemical Communications, 2006, issue 17, p. 1828-1830

  An object of the present invention is to provide an ion conductive composite containing an ionic liquid that can operate safely and in a wide temperature range, has high ion conductivity, and functions as an electrolyte of an electrochemical device.

As a result of intensive studies to solve the above problems, the present inventors have found a solution means having the following configuration, and have completed the present invention.
(1) Porous coordination polymer crystal particles having an average primary particle size of 50 nm or less, and a first ionic liquid held in the first pores of the porous coordination polymer An ion conductive composite comprising:
(2) The ion conductive composite as described in (1) above, wherein the first ionic liquid contains lithium.
(3) The ion conductive composite as described in (1) or (2) above, wherein the first ionic liquid exhibits a plastic crystal phase.
(4) The ion conductive composite according to any one of (1) to (3), wherein the first pore further contains an organic solvent.
(5) The ion-conductive composite according to any one of (1) to (4), wherein the surface of the crystal particles has irregularities.
(6) A plurality of the crystal particles constitutes an aggregate including second pores provided between the crystal particles by partially bonding the crystal particles adjacent to each other, and The ion conductive composite according to any one of (1) to (5), wherein the average pore diameter of the pores is larger than the average pore diameter of the first pore.
(7) The ion conductive composite as described in (6) above, wherein the first pore is a micropore and the second pore is a mesopore.
(8) The ion conductive composite according to (6) or (7), wherein the first ionic liquid is contained in the second pore.
(9) The ion conductive composite as described in any one of (6) to (8) above, wherein the second pore contains an organic solvent.
(10) The first pore further includes an organic solvent, and the organic solvent contained in the second pore is the same as the organic solvent contained in the first pore. The ion conductive composite as described in (9) above, wherein
(11) The ion according to any one of (1) to (5), wherein the ion is a structure that is formed by a plurality of the crystal particles and includes a gap provided between the crystal particles. Conductive composite.
(12) The structure is formed by at least one of a plurality of the crystal particles and the aggregate, and has a gap provided in at least one of the crystal particles and the aggregate. The ion conductive composite according to any one of (6) to (10).
(13) The ion conductive composite as described in (11) or (12) above, wherein the structure is a film or a sheet.
(14) The ion conductive composite according to any one of (11) to (13), wherein the structure has an ion conductive substance in the gap.
(15) The ion conductive composite according to (14), wherein the ion conductive substance contains a second ionic liquid.
(16) The ion conductive composite as described in (15) above, wherein the second ionic liquid is the same as the first ionic liquid.
(17) The ion conductive composite according to any one of (14) to (16), wherein the ion conductive substance contains an organic solvent.
(18) At least one of the first pore and the second pore contains an organic solvent, and the organic solvent contained in the ion conductive material is contained in the at least one The ion conductive composite as described in (17) above, which is the same as the organic solvent.

  According to the present invention, by having crystalline particles of a porous coordination polymer having an average primary particle size of 50 nm or less (hereinafter sometimes referred to as porous coordination polymer nanoparticles), The filling rate of the ionic liquid into the pores of the porous coordination polymer can be improved, and the ionic liquid can be held while suppressing the decomposition of the porous coordination polymer. Moreover, the melting point of the ionic liquid can be greatly lowered by retaining the ionic liquid in the pores of the specific porous coordination polymer nanoparticle. Therefore, by using the ion conductive composite of the present invention as an electrolyte, it is possible to realize an electrochemical device such as a battery or an electric double layer capacitor that has a high ion conductivity and can operate in a wide temperature range.

It is a cross-sectional schematic diagram which shows the ion conductive composite which concerns on one embodiment of this invention. It is a cross-sectional schematic diagram which shows the comparative example of an ion conductive composite. It is a cross-sectional schematic diagram which shows the comparative example of an ion conductive composite. It is a cross-sectional schematic diagram which shows the surface vicinity of the ion conductive composite which concerns on one embodiment of this invention. It is a cross-sectional schematic diagram at the time of compounding the porous coordination polymer nanoparticle and ionic liquid which concern on one embodiment of this invention. It is a cross-sectional schematic diagram which shows the surface vicinity of the comparative example of an ion conductive composite. It is a cross-sectional schematic diagram of the comparative example at the time of compounding a porous coordination polymer and an ionic liquid. It is a cross-sectional schematic diagram which shows the ion conductive composite which concerns on the other embodiment of this invention. It is a schematic diagram which shows the structure which compression-molded the ion conductive composite which concerns on other embodiment of this invention. It is a schematic diagram which shows the structure which compression-molded the ion conductive composite which concerns on other embodiment of this invention. 3 is a nitrogen gas adsorption isotherm at 77K of the ion conductive composite according to Example 1. FIG. Δ and ▲ are filling rates of 0%, ○ and ● are filling rates of 25%, and ▽ and ▼ are filling rates of 50%. White indicates a gas adsorption process, and black indicates a desorption process. It is a nitrogen gas adsorption isotherm in 77K of the comparative example of an ion conductive composite. Δ and ▲ are filling rates of 0%, ○ and ● are filling rates of 25%, and ▽ and ▼ are filling rates of 50%. White indicates a gas adsorption process, and black indicates a desorption process. 2 is a differential scanning calorimetric analysis result of the ion conductive composite according to Example 1. FIG. The solid line indicates the heating process, and the dotted line indicates the cooling process. (a) is 50% filling rate, (b) is 75% filling rate, (c) is 100% filling rate, (d) is 125% filling rate, and (e) is EMI-TFSI alone. It is a differential scanning calorimetric analysis result of the comparative example of an ion conductive composite. The solid line indicates the heating process, and the dotted line indicates the cooling process. (a) is a filling factor of 25%, (b) is a filling factor of 50%, (c) is a filling factor of 100%, and (d) is EMI-TFSI alone. It is a cross-sectional schematic diagram which shows the comparative example of an ion conductive composite. 3 is an Arrhenius plot of the ionic conductivity of the ion conductive composite according to Example 1. FIG. (a) is 100% filling rate, (b) is 75% filling rate, (c) is 50% filling rate, and (d) is EMI-TFSI alone. 4 is an Arrhenius plot of the ionic conductivity of the ion conductive composite according to Example 3. (a) shows the case where ethyl carbitol is added, and (b) shows the case where no ethyl carbitol is added. It is a graph which shows the temperature dependence of ionic conductivity. The ionic conductivity is normalized by the value σ _RT at room temperature. (A) is an ion conductive composite according to Example 4, and (b) is (EMI _0.8 Li _0.2 ) TFSI alone.

  Hereinafter, an ion conductive composite according to an embodiment of the present invention (hereinafter sometimes simply referred to as “composite”) will be described with reference to FIGS.

  As shown in FIG. 1, the complex 1 </ b> A is composed of porous coordination polymer nanoparticles (hereinafter sometimes simply referred to as “nanoparticles”) 2 and a first ionic liquid 3. The porous coordination polymer nanoparticle-ionic liquid composite, and the first ionic liquid 3 is held in the first pores 21 of the porous coordination polymer.

  The porous coordination polymer nanoparticles 2 are composed of a porous coordination polymer. The porous coordination polymer is insulative and is also called MOF (Metal-Organic Framework) or PCP (Porous Coordination Polymer). The porous coordination polymer has a large number of first pores 21 in the micropore region and is uniform because the diameter of the first pores 21 is determined from the crystal structure. . Therefore, the physical properties such as the melting point and ionic conductivity of the first ionic liquid 3 held in the first pore 21 are uniform. Furthermore, the first pores 21 of the porous coordination polymer are derived from the crystal lattice as described above. Therefore, the porous coordination polymer nanoparticles 2 having the first pores 21 having a uniform pore diameter in the micropore region can be produced with good reproducibility.

Examples of porous coordination polymers include:
Zn (MeIM) ₂ (hereinafter referred to as ZIF-8)
Al (OH) (BDC) (hereinafter referred to as Al-MIL-53)
Cr (OH) (BDC) (hereinafter referred to as Cr-MIL-53)
Fe (OH) (BDC) (hereinafter referred to as Fe-MIL-53)
VO (BDC) (hereinafter referred to as V-MIL-47)
Zn ₂ (DOBDC) (hereinafter referred to as Zn-MOF-74)
Mg ₂ (DOBDC) (hereinafter referred to as Mg-MOF-74)
Al (OH) (1,4-NDC)
Cr ₃ O (F, OH) (BDC) ₃ (hereinafter referred to as Cr-MIL-101)
Al ₈ (OH) ₁₅ (BTC) ₃ (hereinafter referred to as Al-MIL-110)
Cu ₃ (BTC) ₂ (hereinafter referred to as HKUST-1)
Zr ₆ O ₄ (OH) ₄ (BDC) ₆ or Zr ₆ O ₆ (BDC) ₆ (hereinafter referred to as UiO-66)
Zr ₆ O ₄ (OH) ₄ (BPDC) ₆ or Zr ₆ O ₆ (BPDC) ₆ (hereinafter referred to as UiO-67)
Zr ₆ O ₄ (OH) ₄ (TPDC) ₆ or Zr ₆ O ₆ (TPDC) ₆ (hereinafter referred to as UiO-68)
ZrO (BDC) (hereinafter referred to as MIL-140)
Etc.

The abbreviations used in the above chemical formula are:
H (MeIM): 2-methylimidazole H ₂ (BDC): terephthalic acid H ₄ (DOBDC): 2,5-dihydroxyterephthalic acid H ₂ (1,4-NDC): 1,4-naphthalenedicarboxylic acid H ₃ ( BTC): 1,3,5-benzenetricarboxylic acid H ₂ (BPDC): 4,4′-biphenyldicarboxylic acid H ₂ (TPDC): H ⁺ dissociated in 4,4 ″ -p-terphenyldicarboxylic acid Represents a residue.

The porous coordination polymer forms a main chain by coordinating an organic ligand to a metal ion. All or part of the organic ligand constituting the porous coordination polymer may be substituted with a ligand having an appropriate functional group (for example, terephthalic acid is substituted with 2-hydroxyterephthalic acid. Such). Examples of the functional group include —OH, —COOH, —NH ₂ , —SO ₃ H, —SO ₃ Li, and —SO ₃ Na. -SO ₃ Li, -SO ₃ Na are especially preferable. This is because when the composite 1A is used as an electrolyte for a battery, lithium ions and sodium ions can be supplied to improve ion conductivity. Further, all or part of the metal ions constituting the porous coordination polymer may be substituted with other metal ions. It is desirable that the metal ions have the same valence.

  Further, the porous coordination polymer is required to have durability against the first ionic liquid 3. A porous coordination polymer in which the main chain is formed by coordination bonding of an organic ligand to a metal ion is equivalent to the case where the metal ion is a Lewis acid and the organic ligand is a Lewis base. When a hard acid and base are combined, the crystalline structure of the porous coordination polymer can be maintained even when it comes into contact with the first ionic liquid 3. According to the HSAB rule, generally, a hard acid and a hard base have a strong bond, and a soft acid and a soft base have a strong bond. In the porous coordination polymer, the metal ion is a Lewis acid and the organic ligand is a Lewis base, and the strength of these bonds dominates the resistance of the porous coordination polymer to the first ionic liquid 3. doing.

  Examples of hard acids, hard bases, soft acids, soft bases, intermediate acids, and intermediate bases can be found in, for example, Thomas, G. Medicinal Chemistry: An Introduction, 2nd edition; Wiley: New York, 2007. Has been.

For example, terephthalic acid, 2,5-dihydroxyterephthalic acid, 1,4-naphthalenedicarboxylic acid, 1,3,5-benzenetricarboxylic acid and the like are hard bases having an RCOO ⁻ structure in the molecule. Therefore, a porous coordination polymer obtained from these compounds and a metal ion that is a hard acid (for example, Al ³⁺ , Cr ³⁺ , Mg ²⁺ , Fe ³⁺ , Zr ^4+, etc.) It has excellent resistance to the ionic liquid 3. Specific examples of such a porous coordination polymer include Al-MIL-53, Al (OH) (1,4-NDC), Al-MIL-110, and metal ions whose metal ions are Al ^3+. Cr-MIL-53, Cr-MIL-101 with Cr ³⁺ , Mg-MOF-74 with metal ion Mg ²⁺ , Fe-MIL-53 with metal ion Fe ³⁺ , Zr ⁴⁺ with metal ion UiO-66, UiO-67, UiO-68, etc. are mentioned.

On the other hand, a porous coordination height obtained from a compound that is a hard base and a metal ion that is an acid having an intermediate hardness (for example, Fe ²⁺ , Co ²⁺ , Zn ²⁺ , Cu ^2+, etc.) The molecule is slightly less resistant to the first ionic liquid 3 than a porous coordination polymer obtained from a hard base and a hard acid. Such porous coordination polymer, specifically, MOF-74 metal ions Zn ²⁺ (Zn), metal ions, and the like HKUST-1 of Cu ^2+.

For example, imidazole is a base with intermediate hardness. Therefore, the porous coordination polymer obtained from the imidazole-based ligand and the metal ion that is an acid having intermediate hardness has excellent resistance to the first ionic liquid 3. For example, all of ZIF (Zeolytic Imidazolate Frameworks) type porous coordination polymers composed of Fe ²⁺ , Co ²⁺ , or Zn ²⁺ are applicable, and a representative one is ZIF-8.

  In the porous coordination polymer, it is preferable that the metal ion does not have a coordination unsaturated site. When the metal ion has a coordination unsaturated site, it becomes easy for the anion of the first ionic liquid 3 to approach the metal ion of the porous coordination polymer. As a result, the bond between the metal ion and the organic ligand is weakened, and the porous coordination polymer may be destroyed. That is, Al-MIL-53, Al (OH) (1,4-NDC), Cr-MIL-53, Fe-MIL-53, and ZIF systems (such as ZIF-8) that do not have coordination unsaturated sites Has excellent resistance to the first ionic liquid 3.

Conversely, Cr-MIL-101, Mg-MOF-74, Zn-MOF-74, and HKUST-1 having coordination unsaturated sites have slightly lower resistance to the first ionic liquid 3. However, although UiO-66, UiO-67, and UiO-68 have coordination unsaturated sites, they are exceptionally highly resistant to the first ionic liquid 3. This is because the metal ion constituting the main chain of these porous coordination polymers is Zr ⁴⁺ , but this Zr atom is 8-coordinated to the surrounding atoms and 7-coordinate even when a coordination unsaturated site is formed. This is because it has a higher coordination number than other porous coordination polymers. When the coordination number is large, the anion of the first ionic liquid 3 cannot easily approach Zr ⁴⁺ , and the porous coordination polymer is not easily destroyed.

  On the other hand, as described above, Cr-MIL-101, Mg-MOF-74, Zn-MOF-74, and HKUST-1 have six-coordinate and non-coordinated metal ions constituting the main chain to surrounding atoms. In the case where a saturated site is formed, the coordination number is small and the coordination number is small. Therefore, the anion of the first ionic liquid 3 can easily approach the metal ion and destroy the porous coordination polymer.

  Whether or not the porous coordination polymer has coordination unsaturated sites can be determined by the crystal structure of the porous coordination polymer. The crystal structure of the porous coordination polymer can be examined by, for example, X-ray diffraction or infrared spectroscopy. The number of coordination unsaturated sites is determined by the type of porous coordination polymer. For example, Cr-MIL-101, Mg-MOF-74, Zn-MOF-74, and HKUST-1 have the same number of coordination unsaturated sites and the number of metal ions. UiO-66, UiO-67, and UiO-68 have one coordination unsaturated site per three metal ions.

  In Cr-MIL-101, Mg-MOF-74, Zn-MOF-74, and HKUST-1, each metal ion is coordinated to six oxygen atoms. Five of the six are oxygen atoms of the organic ligand, and the remaining one is an oxygen atom of a solvent (for example, DMF or water) molecule. By heating such a porous coordination polymer while evacuating, for example, solvent molecules coordinated to metal ions can be removed. As a result, one of the six coordination sites of metal ions is vacant and a coordination unsaturated site is formed.

In UiO-66, UiO-67, and UiO-68, each Zr ⁴⁺ is coordinated to eight oxygen atoms. Of the eight, four are oxygen atoms of the organic ligand, two are oxygen atoms derived from μ ₃ —O, and the remaining two are oxygen atoms derived from μ ₃ —OH. By heating such a porous coordination polymer while evacuating, for example, oxygen atoms coordinated with each Zr ⁴⁺ are changed to four oxygen atoms of the organic ligand and μ ₃ —O. Changes to three oxygen atoms derived from. As a result, one coordination unsaturated site is formed.

  In most porous coordination polymers, the coordination sites of metal ions are all occupied by oxygen atoms and nitrogen atoms of the organic ligand, so there are no coordination unsaturated sites. In the case of the complex 1A composed of the porous coordination polymer and the first ionic liquid 3, the anion of the first ionic liquid 3 is easily coordinated to the coordination unsaturated site of the metal ion, It is considered that the coordination unsaturated site has disappeared. In the present specification, by removing the first ionic liquid 3 in the first pores 21 in the porous coordination polymer and performing heating or the like while evacuating, the coordination unsaturated sites are formed. When it can be formed, it is defined as “the porous coordination polymer has coordination unsaturated sites”.

  Whether or not the coordination unsaturated site is formed by removing the first ionic liquid 3 in the first pore 21 and performing heating or the like while evacuating is determined by, for example, infrared spectroscopy or elemental analysis. This can be confirmed by X-ray diffraction. You may evaluate by the change of the optical characteristic when a solvent is made to adsorb | suck.

In the porous coordination polymer, the metal ion is preferably a typical metal element. The typical metal element refers to a metal element that does not belong to the transition metal series, for example, a metal element belonging to Group 1, Group 2, Group 12 to Group 18 of the periodic table. In other words, electrons are sequentially arranged in the s or p orbit of the outermost shell, and have a characteristic property as a metal thereon. Since typical metal elements do not easily change their valence, the porous coordination polymer containing them in the main chain maintains the crystal structure of the porous coordination polymer even when it comes into contact with the first ionic liquid 3. Can do. On the other hand, when the metal element contained in the main chain is a transition metal element, the valence may change due to contact with the first ionic liquid 3, and the crystal structure of the porous coordination polymer may be destroyed. From this point of view, preferable porous coordination polymers include Al-MIL-53, Al (OH) (1,4-NDC), ZIF-8, and those having a metal ion of Zn ²⁺ among ZIF series. Can be mentioned.

  The porous coordination polymer nanoparticles 2 are synthesized by using a metal compound and an organic compound as raw materials and reacting them in a reaction solvent. Thereby, a metal ion and an organic ligand react, and a coordination bond is formed, and a porous coordination polymer is formed. A metal compound is a source of metal ions, and examples thereof include metal nitrate, metal chloride, and metal oxide. Organic compounds are sources of organic ligands such as terephthalic acid, 1,3,5-benzenetricarboxylic acid, 1,4-naphthalenedicarboxylic acid, 2-methylimidazole, 2,5-dihydroxyterephthalic acid, oxalic acid And fumaric acid.

  The reaction solvent is not particularly limited as long as it can dissolve a metal compound and an organic compound, and examples thereof include water, N, N-dimethylformamide (DMF), tetrahydrofuran (THF), ethanol, methanol and the like. A mixture of two or more of these may be used as the reaction solvent. Moreover, you may use an ionic liquid as a reaction solvent. In addition, an appropriate acid or base may be added to adjust the pH. As the acid, for example, glacial acetic acid or hydrofluoric acid can be used. As the base, for example, triethylamine can be used.

  A porous coordination polymer can be synthesized by dissolving and holding or stirring a metal compound and an organic compound in a reaction solvent. The reaction may be at room temperature or lower. Synthesis may be performed while applying ultrasonic waves to the solution. The reaction may be performed in an atmosphere of an inert gas such as nitrogen gas or argon gas in order to prevent deterioration of the raw material. The porous coordination polymer may be synthesized by a spray drying method in which a solution in which a metal compound and an organic compound are dissolved is sprayed under a reduced pressure atmosphere.

  Here, the porous coordination polymer nanoparticle 2 has an average primary particle diameter of 50 nm or less. Thereby, the filling rate of the 1st ionic liquid 3 in the 1st pore 21 of a porous coordination polymer | macromolecule can be improved. That is, the speed at which the first ionic liquid 3 diffuses through the first pores 21 of the porous coordination polymer is extremely slow. Therefore, as shown in FIGS. 2 and 3, in the coarse particle composite 100 according to a comparative example described later, it is considered that the first ionic liquid 3 remains in the vicinity of the surface of the particle. When the average particle size of the primary particles is 50 nm or less, the porous coordination polymer is decomposed by the first ionic liquid 3 when the first ionic liquid 3 is injected into the first pores 21. While being suppressed, the moving distance until the first ionic liquid 3 reaches the center of the particle 2 can be shortened. As a result, the filling rate of the first ionic liquid 3 can be improved. These points will be described in detail later. The average particle size of the primary particles is desirably 5 to 50 nm, and more desirably 5 to 25 nm.

  In order to obtain porous coordination polymer nanoparticles 2 having a small particle size, the reaction is particularly desired to be performed at a low temperature and for a short time. This is because when the reaction is performed at a high temperature for a long time, the nuclei of the particles precipitated in the solution easily grow into coarse particles. Specifically, the reaction temperature is desirably room temperature (23 ° C.) or lower. A container containing a solvent may be cooled while immersed in ice water or the like.

  The reaction time is preferably 1 hour or less, more preferably within 15 minutes, and particularly preferably within 5 minutes. It is desirable to prepare a solution in which a metal compound is dissolved and a solution in which an organic compound is dissolved separately, and mix them together. This is because the reaction between the metal ion and the organic ligand is completed quickly when the solution is mixed. In order to complete the reaction quickly, it is desirable that the metal compound and the organic compound are almost completely ionized in the solution. In general, since an organic compound has a low ionization degree, it is desirable to add a base to a solution of the organic compound and extract protons from the organic compound to be ionized. The molar equivalent of the base is preferably equal to or higher than the molar equivalent of the proton to be extracted, and more preferably twice or more in excess. Triethylamine is desirable as the base. In order to complete the reaction rapidly, it is desirable that either the metal ion or the organic ligand is present in an excess amount relative to the stoichiometric ratio of the porous coordination polymer. Specifically, it is desirable to exist in excess of 2 times or more, more desirably 3 times or more. In addition, as described above, since the ionization degree of the organic compound is low, it is necessary to prepare the ligand capable of reacting sufficiently so that the organic ligand is more excessive than the metal ion. desirable.

  In addition, there is a method in which a solution in which a metal compound is dissolved and a solution in which an organic compound is dissolved are prepared separately, and the other solution is poured all at once while strongly stirring one of the solutions with a stirrer or the like. desirable. Since the reaction between the metal ion and the organic ligand can be completed in an instant, not only finer porous coordination polymer nanoparticles 2 can be obtained, but also as shown in FIG. Can be formed. This is due to the fast completion of the reaction.

  Forming fine irregularities 22 on the surface of the nanoparticles 2 in this way is desirable because the first ionic liquid 3 can be easily introduced into the porous coordination polymer. That is, in the porous coordination polymer in which the main chain is formed by coordination bonding of the organic ligand 24 to the metal ion 23, when the fine irregularities 22 are formed on the surface, FIG. As shown, the first ionic liquid 3 first accumulates in this recess and then diffuses into the first pores 21 of the porous coordination polymer. The surface of the first ionic liquid 3 accumulated in the recess has a large curvature. That is, the surface energy is large. This curvature is relatively close to the curvature when taken into the first pore 21. That is, since the increase in surface energy when the first ionic liquid 3 is introduced into the first pore 21 is small, the introduction of the first ionic liquid 3 into the first pore 21 is easy. Become. On the other hand, in the case of a smooth surface as shown in FIG. 6, there is no place where the first ionic liquid 3 accumulates. Therefore, the first ionic liquid 3 outside the nanoparticles 2 has a very large curvature and a very high surface energy. small. For this reason, when the first ionic liquid 3 is introduced into the first pores 21, the decrease in the curvature of the ionic liquid is extremely large as shown in FIG. That is, the surface energy must change to a much higher state. Therefore, it is difficult to introduce the first ionic liquid 3 into the porous coordination polymer having a smooth surface.

  After the reaction, the porous coordination polymer nanoparticles 2 precipitated or dispersed in the reaction solvent are collected by a technique such as filtration, natural sedimentation, or centrifugation. Since the porous coordination polymer nanoparticles 2 easily pass through the filter paper, spontaneous sedimentation or centrifugation is desirable.

  It is desirable to remove unreacted substances and impurities remaining on the surface of the porous coordination polymer nanoparticles 2 and in the first pores 21. If unreacted substances and impurities remain, when the porous coordination polymer and the first ionic liquid 3 are combined, the first pores 21 are narrowed or completely formed by the unreacted substances and impurities. It becomes difficult to inject the first ionic liquid 3 into the first pore 21. In addition, there is a concern that the physical properties of the first ionic liquid 3 change due to the mixing of impurities, making it difficult to control the melting point. Further, when the composite 1A is used as an electrolyte for an electrochemical device, it causes problems such as metal deposition, gas generation, and deterioration of cycle characteristics.

  As a method for removing unreacted substances and impurities, the porous coordination polymer may be washed with a solvent. The solvent used for washing is preferably water, methanol, THF, or DMF. Water and methanol are particularly desirable. This is because water and methanol have a small molecular size, so that they easily enter the first pores 21 of the porous coordination polymer and can easily remove unreacted substances and impurities in the first pores 21. . The porous coordination polymer may be immersed in a solvent for a long time. The immersion time is desirably 12 hours or more, and more desirably 24 hours or more.

  As another method for removing unreacted substances and impurities, there is a method of desorbing molecules and ions adsorbed by heat treatment. In order to remove organic substances, it is desirable to perform heat treatment in air or in an oxygen atmosphere. In the case of a volatile substance, vacuum heat treatment is desirable. The heating temperature is preferably 100 to 300 ° C.

  It can be confirmed by gas adsorption measurement that the fine irregularities 22 are formed on the surface. The gas is not particularly limited as long as it is inert to the porous coordination polymer, and nitrogen gas is preferably used. When the irregularities 22 are formed on the surface, the volume of the micropores per weight of the porous coordination polymer decreases as is apparent from FIG. Therefore, the formation of irregularities on the surface can be known by examining the volume of the micropores by gas adsorption measurement. In addition, you may confirm uneven | corrugated formation by SEM and TEM.

  Whether or not the porous coordination polymer is formed can be confirmed by performing powder X-ray diffraction (XRD) measurement of the obtained porous coordination polymer and analyzing the obtained diffraction pattern. In addition, an appropriate peak is selected from the obtained diffraction pattern, the half width is measured, and the particle size of the porous coordination polymer, that is, the average particle size of the primary particles is evaluated by applying Scherrer's formula. be able to. The average particle diameter of the primary particles may be evaluated by observing the particles with SEM or TEM.

  The porous coordination polymer nanoparticle 2 made of such a porous coordination polymer is used as an insulating material having insulating properties, that is, not having electron conductivity, and a first ionic liquid is formed inside the first pore 21. 3 is held. Thereby, 1 A of composite_body | complex has what has ion conductivity, but does not have electronic conductivity, and can be used as an electrolyte of a battery or an electrical double layer capacitor.

  By setting the first pore 21 to the size of the micropore region, the melting point of the ionic liquid when a mesopore such as porous glass is filled with the ionic liquid (see, for example, Patent Document 1), and the micropore Compared with the melting point of the ionic liquid expected when pores having a considerable diameter are filled with the ionic liquid, the first ionic liquid 3 can be kept in a liquid state without being substantially solidified. become.

  This is because when the size of the pores that hold the first ionic liquid 3 is in the micropore region, the number of ion pairs that can exist in the pores is less than or equal to the order of 10 pairs in the diameter direction of the pores. Due to the decrease to When the first ionic liquid 3 is solidified, the cations and anions constituting the first ionic liquid 3 need to be regularly arranged by hydrogen bonds. However, when the pore size is in the micropore region, the number of ions present in the pore is extremely reduced. Therefore, it is difficult to find other ions having different polarities, making it difficult to form ion pairs. Furthermore, it becomes virtually impossible to take a crystal structure in which cations and anions are regularly arranged, and the first ionic liquid 3 does not coagulate. As a result, it is considered that the first ionic liquid 3 can always maintain a liquid state.

  Some porous coordination polymers have the property that the size of the first pores 21 is expanded or contracted by the molecules present in the first pores 21. When the first ionic liquid 3 is filled in the first pores 21 of the porous coordination polymer nanoparticle 2 made of such a porous coordination polymer, the cation and the anion are easily arranged regularly. As described above, the first pore 21 is deformed to an optimum size. Therefore, the first ionic liquid 3 is considered to have a stable crystalline state and an increased melting point. Examples of the porous coordination polymer having the property that the size of the first pore 21 expands or contracts include Al-MIL-53, Cr-MIL-53, Fe-MIL-53, and the like.

  In the catalyst field of the International Union of Applied Chemistry (IUPAC), micropores are defined as pores with a diameter of 2 nm or less. Similarly, pores with a diameter of 2 to 50 nm are mesopores, and pores with a diameter of 50 nm or more are macropores. Is defined. The ionic liquid generally means a salt having a melting point of 100 ° C. or lower. However, in the present specification, a salt that has a melting point of 100 ° C. or lower when held in the first pore 21 is referred to as an ionic liquid.

  The diameter of the first pores 21 is preferably 1.5 nm or less, whereby the melting point of the first ionic liquid 3 can be further greatly reduced. The diameter of the first pore 21 is preferably 0.3 nm or more. This is because it is difficult for ions constituting the first ionic liquid 3 to be present in the first pores 21 smaller than 0.3 nm. The diameter of the first pore 21 can be measured, for example, by a gas adsorption method or can be obtained from a crystal structure obtained by X-ray structure analysis. When measuring by the gas adsorption method, the composite 1A is washed with water, methanol, or the like to remove the first ionic liquid 3 or adsorbate in the first pores 21, and then heat-treated in a vacuum. For example, the measurement may be performed after removing the solvent used for washing.

  In the present specification, the diameter of the first pore 21 is the average value of the measured pore diameter distribution (average pore diameter), or the first fine particles derived from the crystalline structure of the porous coordination polymer nanoparticles 2. In the case of having the holes 21, the diameter of the sphere inscribed in the inner wall of the first pore 21 is set, and when the diameter of the first pore 21 is 2 nm or less, the first pore 21 is a micropore. It was an area.

  The shape of the first pore 21 may be one-dimensional, two-dimensional, or three-dimensional, but is preferably three-dimensional. When the shape of the first pore 21 is three-dimensional, the ion conduction path is most reliably constructed. In other words, the ion conduction path is formed isotropically, the interconnection is facilitated, and the ionic conductivity is increased.

  The shape of the porous coordination polymer nanoparticle 2 is not particularly limited, and may be any shape such as a sphere, a cube, a cuboid, a regular octahedron, other polyhedrons, a tree shape, a needle shape, a rod shape, a plate shape, and the like. Also good. That is, the particle in the porous coordination polymer nanoparticle 2 is not limited to a spherical shape, and is a concept including shapes other than a spherical shape as long as the effect is not impaired.

  Examples of the method for injecting the first ionic liquid 3 into the first pore 21 include a method in which a mixture of the particles 2 and the first ionic liquid 3 is allowed to stand. In order to promote the diffusion of the first ionic liquid 3 into the first pores 21, it is desirable to heat the mixture. The heating temperature is preferably 100 to 200 ° C. This is because the diffusion rate of the first ionic liquid 3 increases as the temperature increases, whereas the porous coordination polymer tends to be decomposed by the first ionic liquid 3 when the temperature is too high. The standing temperature is appropriately adjusted depending on the combination of the porous coordination polymer and the first ionic liquid 3.

  The heating time is preferably within 25 hours. This is because if the heating time is too long, the porous coordination polymer is easily decomposed by the first ionic liquid 3. The shorter the moving distance until the first ionic liquid 3 reaches the center of the porous coordination polymer nanoparticle 2 through the first pore 21, the more reliably the first ionic liquid 3 is attached to the nanoparticle 2. It becomes possible to inject into the inside first pore 21. Even when heated to 200 ° C., the rate at which the first ionic liquid 3 diffuses through the first pores 21 of the porous coordination polymer is estimated to be about 1 nm / h (hour). As described above, since the heating time is preferably within 25 hours, the average particle diameter of the primary particles of the porous coordination polymer nanoparticles 2 is 50 nm or less.

  In addition, in order to prevent adsorption of gas, particularly moisture, to the first pores 21 and the first ionic liquid 3, the injection process of the first ionic liquid 3 into the porous coordination polymer is performed in, for example, a vacuum or It is preferable to carry out in a dry atmosphere with a dew point of −20 ° C. or lower. Furthermore, in order to prevent chemical reactions such as oxidation and reduction of the porous coordination polymer and the ionic liquid, it is more preferable to perform the implantation treatment in a vacuum or in an inert gas atmosphere such as nitrogen gas or argon gas.

  Examples of the first ionic liquid 3 include imidazolium salts, pyrrolidinium salts, pyridinium salts, quaternary ammonium salts, quaternary phosphonium salts, and sulfonium salts. Alkali metal salts such as lithium salts and sodium salts, and alkaline earth metal salts such as magnesium salts may be used. Among these, an imidazolium salt having a relatively small cation size, a low melting point, and high ion conductivity is particularly preferably used.

Examples of the anion include halogen such as Cl and Br, BF ₄ , PF ₆ , CF ₃ SO ₃ , FSO ₂ NSO ₂ F (FSI), CF ₃ SO ₂ NSO ₂ CF ₃ (TFSI), and C ₂ F ₅ SO _{2. NSO 2 C 2 F 5 (BETI} ), SCN, ClO 4, SO 3 C 6 H 4 CH 3 (p- toluenesulfonate), and the like. Among these, TFSI that can lower the melting point and has high ion conductivity is particularly preferably used.

  These ionic liquids may be used alone or in combination of two or more. As the battery electrolyte, a lithium salt, sodium salt, or magnesium salt dissolved is particularly preferably used. A lithium salt is particularly desirable. In other words, it is desirable that the first ionic liquid 3 contains lithium. As shown in the literature (for example, Y. Umebayashi et al., J. Phys. Chem. B 2007, 111, 13028.), in the case of an ionic liquid alone, lithium ion is a molecule in which a plurality of anions are coordinated. Existing. In this state, since the size of the molecule is large, the mobility of lithium ions is lowered. However, when the first ionic liquid 3 is introduced into the first pore 21, an interaction works between the anion coordinated with the lithium ion and the inner wall of the first pore 21, and the lithium ion And the anion is weakened. As a result, the binding / dissociation between the lithium ion and the anion becomes easy, and the lithium ion can move so as to jump between the anions. In this conduction mechanism, the smaller the cation size, the smoother movement in the first pore 21 of the porous coordination polymer nanoparticle 2 is possible. Since lithium ions have a small ion radius, they can move smoothly in the first pores 21 of the porous coordination polymer nanoparticles 2. Therefore, the ion conductive composite 1A can be suitably used as an electrolyte of a lithium ion battery. The proportion of lithium ions in the cation in the ionic liquid is preferably 10 to 50%, more preferably 10 to 30% in terms of molar ratio. When the amount of lithium ions is too small, it becomes difficult to function as an electrolyte of the battery. When the amount of lithium ions is too large, the interaction between lithium ions and anions becomes large, and the conductivity of lithium ions tends to extremely decrease.

By injecting such a first ionic liquid 3 into the first pores 21 of the porous coordination polymer nanoparticles 2, a composite 1A is obtained. At this time, the porous coordination polymer having a slightly low resistance to the first ionic liquid 3 as described above has a high degree of dissociation and the first ionic liquid 3, for example, 1-ethyl, in which the cation and the anion easily move individually. When -3-methylimidazolium bis (trifluoromethanesulfonyl) imide (EMI-TFSI) is used, it may be destroyed. When the complex 1A is formed using such a porous coordination polymer, the first ionic liquid 3 having a low dissociation degree, for example, pyrrolidinium ion, piperidinium ion, pyridinium ion, aliphatic quaternary as a cation. One containing an ammonium ion, an aliphatic quaternary phosphonium ion, an aliphatic tertiary sulfonium ion, or a halogen such as Cl ⁻ or Br ⁻ as an anion, BF ₄ ⁻ , PF ₆ ⁻ , ClO ₄ ⁻ , SO ₃ C ₆ H ₄ What contains CH ₃ ⁻ (p-toluenesulfonate), SCN ⁻ or the like may be used.

  The mixing ratio of the porous coordination polymer and the first ionic liquid 3 is such that the total volume of the first pores 21 included in the porous coordination polymer and the volume of the first ionic liquid 3 are equal. However, it may be mixed in such a ratio that the first ionic liquid 3 becomes too little or too much. However, even when the amount of the first ionic liquid 3 is too small, the volume of the first ionic liquid 3 with respect to the total volume of the first pores 21 is preferably 20% or more, more preferably 50% or more. More preferably, it is 75% or more. As the amount of the first ionic liquid 3 is smaller, the path of the first ionic liquid 3 is more likely to be interrupted, and ion conduction may be interrupted. Moreover, when the 1st ionic liquid 3 becomes excess, it is preferable that the volume of the 1st ionic liquid 3 with respect to the total volume of the 1st pore 21 is less than 200% (2 times). In particular, when the purpose is to lower the melting point, when it becomes 200% (twice) or more, the excess first ionic liquid 3 covers the outer periphery of the porous coordination polymer, and the ionic conductivity of the composite 1A is as follows. The rate is limited by the first ionic liquid 3 existing outside the first pore 21. In this case, in particular, even if the first ionic liquid 3 in the first pore 21 is in a liquid state, the surplus first ionic liquid 3 existing outside the first pore 21 is in a solid state. In the temperature range, the ionic conductivity of the composite 1 </ b> A is limited by the solid first ionic liquid 3. Therefore, there is a possibility that the effect of lowering the melting point of the first ionic liquid 3 by holding the first ionic liquid 3 in the first pores 21 in the micropore region may not be obtained.

  The fact that the first ionic liquid 3 is held inside the first pore 21 of the porous coordination polymer is, for example, the differential scanning calorimetry (DSC) of the first ionic liquid 3 alone and the complex 1A. It is only necessary to confirm whether or not the appearance temperature of the peak indicating exotherm or endotherm is different between the case of the first ionic liquid 3 alone and the case of the complex 1A. The composite 1A may not show any exothermic or endothermic peak. Or when the 1st ionic liquid 3 exists excessively with respect to the volume of the 1st pore 21 of a porous coordination polymer, it may show the same melting point as the case of the 1st ionic liquid 3 alone. is there. In such a case, the composite 1A is evaluated while changing the measurement temperature by a method such as a solid nuclear magnetic resonance (NMR) analysis method or an AC impedance method, and the melting point in the case of the first ionic liquid 3 alone is evaluated. By confirming the presence or absence of the phase transition behavior at low temperature, it can be determined whether or not the first ionic liquid 3 is present in the first pores 21 of the porous coordination polymer.

  When the crystal structure of the porous coordination polymer changes depending on the type of molecules occluded inside the first pore 21, the first fine structure is analyzed based on the X-ray diffraction (XRD) pattern analysis. It can also be confirmed that the first ionic liquid 3 is held in the hole 21. For example, when Al-MIL-53 is used as the porous coordination polymer, the monoclinic structure is obtained when only moisture is adsorbed in the first pores 21 by Al-MIL-53 alone. . On the other hand, when EMI-TFSI which is the 1st ionic liquid 3 exists in the 1st pore 21 of Al-MIL-53, it has an orthorhombic structure. Therefore, the presence and type of the substance occluded in the first pore 21 can be determined from the analysis of the X-ray diffraction (XRD) pattern.

  The kind and composition of the porous coordination polymer and the first ionic liquid 3 used are, for example, elemental analysis, X-ray diffraction (XRD) measurement, nuclear magnetic resonance (NMR) analysis, infrared absorption analysis (IR). What is necessary is just to specify by.

  In addition, you may use the ionic liquid which shows a plastic crystal phase (plastic crystal phase) as the 1st ionic liquid 3 mentioned above. Plastic crystals, also called plastic crystals, are a group of materials that are solid but exhibit high ionic conductivity. Unlike the crystalline state where the ions are almost completely fixed, the ions can move freely to some extent in the plastic crystal phase. For this reason, ions are said to hop through the defects in the crystal and exhibit high ionic conductivity.

  When an ionic liquid exhibiting a plastic crystal phase is introduced into the first pores 21 of the porous coordination polymer nanoparticles 2, the ionic liquid in the first pores 21 becomes a plastic crystal phase having a disordered structure. Form. That is, since defects are introduced at a high density, ion hopping conduction is facilitated. In addition, since the porous coordination polymer is made into nanoparticles, the ionic liquid can be filled with high density. Due to these two effects, when an ionic liquid exhibiting a plastic crystal phase is combined with a porous coordination polymer, ion conductivity can be increased.

  An ionic liquid exhibiting a plastic crystal phase also becomes a liquid in the same manner as a normal ionic liquid when heated, and can be combined with a porous coordination polymer in the same manner as described above.

  Any ionic liquid that exhibits a plastic crystal phase alone can be used as the first ionic liquid 3 without any particular limitation. For example, pyrrolidinium salts and quaternary ammonium salts are preferably used. In particular, the pyrrolidinium salt is preferable because the size of the cation is relatively small, so that it easily diffuses in the first pores 21 of the porous coordination polymer and can improve the filling amount, that is, the ionic conductivity becomes high.

  Moreover, 1 A of composites may contain the organic solvent. That is, the composite 1 </ b> A may further contain an organic solvent in the first pores 21. When the organic solvent is dissolved in the first ionic liquid 3, the degree of dissociation of the first ionic liquid 3 is improved, and the ionic conductivity is improved. This is because the organic solvent coordinates with the ions constituting the first ionic liquid 3 to form a solvate and facilitate dissociation of the cation and the anion.

  As an organic solvent, what contains an oxygen atom in a molecule | numerator is desirable. This is because an organic molecule containing an oxygen atom has a large polarity, so that it is easy to form a solvation with ions, and the ionic conductivity is particularly improved. Ethylene carbonate, propylene carbonate, γ-butyrolactone, diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate, diglyme, triglyme, tetraglyme, ethyl carbitol, and cellosolve acetate are easy to form solvates with ions, and especially improve ionic conductivity desirable. Since it is easy to introduce into the first pore 21 of the porous coordination polymer, those having a linear molecular structure are desirable, and diglyme, triglyme, tetraglyme, ethyl carbitol, and cellosolve acetate are particularly desirable.

Next, the composite_body | complex which concerns on other embodiment of this invention is demonstrated based on FIGS.
As shown in FIG. 8, the composite 1B has an average pore diameter larger than the first pores 21 derived from the crystalline structure of the porous coordination polymer between the porous coordination polymer nanoparticles 2 and 2. The second pores 4 having the above are formed. In other words, in the composite 1B, the plurality of porous coordination polymer nanoparticles 2 include the second fine particles provided between the nanoparticles 2 and 2 in which the adjacent nanoparticles 2 and 2 are partially bonded to each other. An assembly including the holes 4 is formed. The average pore diameter of the second pore 4 is larger than the average pore diameter (diameter) of the first pore 21. In the present embodiment, the first pore 21 is a micropore, and the second pore 4 is a mesopore.

  In the composite 1B, the porous coordination polymer nanoparticles 2 and 2 are integrated by continuous connection of crystals. Thereby, while facilitating introduction of the ionic liquid by nano-sizing, the movement of ions between the porous coordination polymer nanoparticles 2 and 2 becomes smooth, and the strength of the composite 1B is improved. In FIG. 8, the second pores 4 are voids, but some or all of them may be filled with an ion conductive material to be described later, or all of them may be filled with the first ionic liquid 3. Particularly desirable. By filling the second pores 4 with an ion conductive material such as the first ionic liquid 3, the conduction of ions between the nanoparticles 2 and 2 becomes smoother. The second pore 4 may contain an organic solvent. Examples of the organic solvent include the same organic solvents as exemplified in the above-described embodiment. When the organic solvent is included in the second pore 4, it is preferable to include the same organic solvent as the organic solvent included in the first pore 21.

  The average pore diameter of the second pores 4 is desirably 5 to 50 nm. If the second pores 4 are too small, the number of the first pores 21 connected thereto is too small, and the second pores 4 hardly contribute to ion conduction. In addition, by setting the average pore diameter of the second pores 4 to 50 nm or less, when the composite 1B is compression-molded, the nano-particles 2 and 2 are more compact than when the composite 1A is simply compression-molded. Since the space is reduced, the occupied volume of the composite 1B in the compression molded body is increased. Since the complexed first ionic liquid 3 is difficult to solidify, the ionic conductivity at a low temperature increases when the volume occupied by the complex 1B is large. The average pore diameter of the second pores 4 can be measured by a gas adsorption method or a mercury intrusion method. The gas adsorption method is desirable when the second pore 4 is a mesopore, and the mercury intrusion method is desirable when the second pore 4 is a macropore (diameter 50 nm or more).

  In order to produce the composite 1 </ b> B having the second pores 4, a device may be added to the method for producing the porous coordination polymer nanoparticles 2. For example, the solution may be continuously stirred or left after the porous coordination polymer nanoparticles 2 are formed in the solution. By this operation, while the surface of the generated nanoparticle 2 is repeatedly dissolved and precipitated, it is bonded to the adjacent nanoparticle 2. The temperature of stirring or standing may be room temperature, low temperature, or high temperature. In order to promote the bonding between the nanoparticles 2 and 2, an additional raw material may be added.

  In order to confirm that the second pores 4 are formed, the gas adsorption measurement may be performed after removing the first ionic liquid 3 and the like by washing by the method described above. For example, when the second pore 4 which is a mesopore is formed, the adsorption is usually observed at a relative pressure (a value obtained by dividing the gas pressure by the saturated vapor pressure) 0.2 to 0.95. Moreover, hysteresis is observed in adsorption and desorption. As another method, the formation of the second pores 4 may be confirmed by observing particles with SEM or TEM.

  The crystal particle diameter of the nanoparticles 2 in the aggregate in which the nanoparticles 2 and 2 are bonded, that is, the average particle diameter of the primary particles may be defined by a value obtained from XRD according to Scherrer's equation. When obtained by SEM or TEM observation, the particle shape of the primary particles may be obtained by extrapolation as shown in FIG. In addition, although the aggregate | assembly of FIG. 8 has illustrated the thing in which the porous coordination polymer nanoparticle 2 was irregularly arranged, the nanoparticle 2 may be regularly arranged. The shape of the aggregate is not particularly limited, and for example, a desired shape such as a spherical shape, a cube shape, a rectangular parallelepiped shape, a regular octahedron shape, a polyhedron shape, a dendritic shape, a needle shape, a rod shape, or a plate shape is adopted.

  On the other hand, as shown in FIG. 9, the composite 1C is a structure obtained by compression-molding the porous coordination polymer nanoparticles 2 into a sheet shape. The structure can be formed into a film instead of a sheet. Moreover, the structure may be comprised from the aggregate | assembly of the nanoparticle 2, and may be comprised from what the nanoparticle 2 and the aggregate | assembly of the nanoparticle 2 were mixed. That is, the structure may be formed by at least one of the plurality of nanoparticles 2 and the aggregate described above. In this embodiment, it is formed by a plurality of nanoparticles 2, that is, the composite 1A. When the composite 1C which is such a structure is used as an electrolyte of a battery or an electric double layer capacitor, the structure 1C has a dense structure, so that the ion conduction path between the nanoparticles 2 and 2 is easily connected. Become. Therefore, the composite 1C is a good ion conductor.

  In the structure obtained by compression-molding the porous coordination polymer nanoparticles 2, a gap 6 is formed between at least one of the porous coordination polymer nanoparticles 2 and 2 and between the aggregates. . In this embodiment, a gap 6 is formed between the nanoparticles 2 and 2. In the gap 6, an ion conductive material 5 is preferably present as shown in FIG. The presence of the ion conductive material 5 in the gap 6 establishes an ion conduction path.

  Examples of the ion conductive substance 5 include water, an organic electrolyte, an ionic liquid, and an ion conductive polymer. Among these, the ion conductive material 5 preferably contains an ionic liquid (second ionic liquid) from the viewpoint of high ion conductivity and low vapor pressure. Unlike ordinary organic electrolytes, ionic liquids with low vapor pressure are not lost by evaporation. In particular, when the same substance (ionic liquid) as the first ionic liquid 3 held in the first pores 21 of the porous coordination polymer is used, the inside and outside of the nanoparticles 2 of the composite 1C are used. This is preferable because the ion conduction becomes smoother.

  Moreover, it is preferable that the ion conductive substance 5 contains an organic solvent. Examples of the organic solvent include the same organic solvents as exemplified in the above-described embodiment. Moreover, when the ion conductive substance 5 contains an organic solvent, it is preferable to contain the same organic solvent as the organic solvent contained in the first pore 21 and the second pore 4.

  A solid ion conductive material may be used as the ion conductive material 5. Examples of the solid ion conductive material include particles of an ion conductive polymer, particles of an inorganic ion conductive material, and the like. In general, although solid ion conductive materials have low ion conductivity, the composite 1C is responsible for the main ion conduction path, and the ion conductive material 5 is an auxiliary position. small. Among solid ion conductive materials, it is particularly preferable to fill the gap 6 with an ion conductive polymer from the viewpoint of easily maintaining the shape of the structure.

  The structure is obtained by, for example, pressure-molding the porous coordination polymer nanoparticles 2 by a known method such as uniaxial pressing, isostatic pressing, roller rolling, or extrusion molding. Alternatively, the structure can be obtained by, for example, forming a slurry in which the porous coordination polymer nanoparticles 2 are dispersed in a solvent by a known sheet forming method such as tape casting, slip casting, spin coating, and drying. . The same applies to an aggregate alone or an aggregate.

  The first ionic liquid 3 is injected into the first pores 21 of the porous coordination polymer of the structure thus obtained. The injection method is as described above. When the ion conductive material 5 is used, the ion conductive material 5 is usually injected into the gap 6 after the first ionic liquid 3 is injected. For example, the ion conductive material 5 is a mixture of the nanoparticles 2 or the aggregates of the nanoparticles 2 and the solid (powder) ion conductive material 5, or liquid ions in the nanoparticles 2 or the aggregates of the nanoparticles 2. The conductive material 5 may be formed in the gap 6 by using it as a solvent. In addition, after the first ionic liquid 3 is injected into the first pores 21 of the porous coordination polymer that is an assembly of the nanoparticles 2 and the nanoparticles 2, the composite 1A and the composite 1B after the injection are injected. You may shape | mold into a desired shape. Then, the ion conductive material 5 may be present in the gap 6.

Summarizing the method of injecting the exemplified ion conductive material 5 into the gap 6, the following (i) to (iii) are obtained.
(I) After molding and injecting the first ionic liquid 3, a liquid ion conductive material 5 is injected into the gap 6.
(Ii) After the first ionic liquid 3 is injected to form the composites 1A and 1B, the liquid ion conductive material 5 is injected into the gap 6.
(Iii) After injecting the first ionic liquid 3, the composites 1A and 1B are molded together with the solid (powder) ion conductive material 5 to inject the ion conductive material 5 into the gap 6.

  The structure 1C in FIGS. 9 to 10 described above is an example in which the porous coordination polymer nanoparticles 2 are irregularly arranged, but the nanoparticles 2 may be regularly arranged. Good. This also applies to the case of an aggregate alone or an aggregate. In addition, the shape of the structure or composite 1C is not particularly limited, and for example, a desired shape such as a sphere, a cube, a rectangular parallelepiped, a regular octahedron, another polyhedron, a tree shape, a needle shape, a rod shape, or a plate shape is adopted. .

  Furthermore, the composites 1B and 1C may contain an additive such as a binder, for example, as long as the effects of the present invention are not impaired.

  The composites 1A to 1C according to the embodiments of the present invention described above can be used for electrochemical devices such as batteries and capacitors. Such an electrochemical device can be obtained by disposing an electrolyte layer including the composites 1A to 1C of each embodiment between a pair of electrodes and enclosing it in an exterior body.

  As the electrode, an electrode containing an active material, for example, a sintered body of an active material such as a metal oxide or a composite oxide, a material in which an active material is solidified with a conductive agent, a metal, a carbon-based material, or the like is used. That's fine. The electrode and the composites 1A to 1C may be in contact with each other through an electrolytic solution or the like. However, if the electrodes and the composites 1A to 1C are in direct contact, the electrode and the ionic liquid (or ion conductive material) inside the composites 1A to 1C It is preferable because ions can be directly exchanged between them.

  As the exterior body, a generally used form and material may be used, but it may be simply covered with an insulating resin or the like.

  When the melting point of the ionic liquid in the composites 1A to 1C according to each embodiment is higher than the melting point of the ionic liquid alone, the composites 1A to 1C are used as an ionic liquid absorbent for applications such as liquid leakage prevention. be able to. With a general porous absorbent, the absorbed ionic liquid may leak again. On the other hand, when the specific porous coordination polymer is used as the adsorbent and the composites 1A to 1C of the respective embodiments are formed, the absorbed ionic liquid is immediately solidified. Can be prevented.

  Furthermore, when the melting point of the ionic liquid in the composites 1A to 1C according to each embodiment is higher than the melting point of the ionic liquid alone, it is possible to concentrate lithium ions and the like in the ionic liquid.

  For example, the melting point of EMI-TFSI in a composite of Al-MIL-53 and EMI-TFSI is 56 ° C, and the melting point of EMI-TFSI alone is -17 ° C. When Al-MIL-53 powder is put into an ionic liquid in which lithium salt is dissolved and maintained at about 65 ° C., ions in the pores are only obtained when lithium ions enter the pores of Al-MIL-53. The liquid solidifies (because the melting point of the ionic liquid increases when a large amount of lithium salt is dissolved). Therefore, it is possible to fill the ionic liquid in which the lithium ion concentration is increased in the pores of Al-MIL-53.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated concretely, this invention is not limited to these Examples.

[Example 1 and Comparative Example]
As crystalline particles of an insulating porous coordination polymer having a first pore, commercially available ZIF-8 (hereinafter referred to as ZIF-8-bulk), and ZIF-8 ( This is hereinafter referred to as ZIF-8-nano). These all have first pores in the micropore region with a diameter of 2 nm or less.

<ZIF-8-bulk>
The ZIF-8-bulk powder was washed with methanol and dried to remove molecules adsorbed inside the first pores. X-ray diffraction (XRD) measurement was performed, and it was confirmed that ZIF-8-bulk had a crystal structure of ZIF-8. From the Scherrer equation, it was confirmed that the crystallite size of ZIF-8-bulk, that is, the average particle size of primary particles was 200 nm.

<ZIF-8-nano>
H (MeIM) was used as the organic ligand source, Zn (NO ₃ ) ₂ .6H ₂ O as the metal ion source, and methanol as the reaction solvent. A solution A was prepared by dissolving 14.8 mmol (mmol) of H (MeIM) and 29.6 mmol of triethylamine in 75 mL of methanol. Further, the methanol of 75 mL, to prepare a solution B obtained by dissolving _{Zn (NO 3) 2 · 6H} 2 O of 3.7 mmol. While solution B was stirred with a magnetic stirrer, all of solution A was poured quickly. The reaction temperature was room temperature (23 ° C.). Stirring was continued for 1 hour to obtain ZIF-8-nano particles. Next, ZIF-8-nano particles were separated by centrifugation, washed with methanol, centrifuged, and dried at room temperature for 1 hour to obtain ZIF-8-nano powder.

  X-ray diffraction (XRD) measurement was performed, and it was confirmed that ZIF-8-nano has a crystal structure of ZIF-8. From the Scherrer equation, it was confirmed that the crystallite size of ZIF-8-nano, that is, the average particle size of primary particles was 12 nm.

  The first ionic liquid was injected into the first pores of ZIF-8-bulk and ZIF-8-nano. Specifically, as the first ionic liquid, 1-ethyl-3-methylimidazolium bis (trifluoromethanesulfonyl) imide (hereinafter may be referred to as EMI-TFSI) which is an imidazolium salt. Using.

Next, ZIF-8-bulk and ZIF-8-nano were each vacuum dried at 150 ° C. for 12 hours to remove adsorbed molecules in the first pores. A porous coordination polymer (ZIF-8-bulk, ZIF-8-nano) was brought into a glove box having a dew point of −20 ° C. or less filled with argon gas. The porous coordination polymer powder and the first ionic liquid were mixed and heat-treated at 200 ° C. in an argon gas atmosphere. There are two heating times: 25 hours and 75 hours. The mixing ratio was an arbitrary ratio such that the volume occupancy of the first ionic liquid was 0 to 125% with respect to the first pore volume of the porous coordination polymer. The calculation was performed assuming that the pore volume of ZIF-8 was 0.64 cm ³ / g and the density of EMI-TFSI was 1.52 g / cm ³ .

  The sample heat-treated for 75 hours turned yellow in both cases of ZIF-8-bulk and ZIF-8-nano. ZIF-8 was a white powder, EMI-TFSI was a colorless and transparent liquid, and the mixture before heating was white. This discoloration is considered to be due to ZIF-8-bulk and ZIF-8-nano being decomposed by EMI-TFSI.

The sample heat treated for 25 hours remained white. Further, when XRD measurement was performed, an XRD pattern derived from the crystal structure of ZIF-8 was obtained. That is, the crystal structure of ZIF-8 is retained after the heat treatment for 25 hours. Therefore, ZIF-8-bulk and ZIF-8-nano are not decomposed by the heat treatment for 25 hours, and the crystal structure is maintained.
Based on the above results, evaluation of composites produced by heat treatment for 25 hours will proceed.

  The results of nitrogen gas adsorption measurement of the obtained composite are shown in FIGS. The measurement temperature is 77K. The horizontal axis is the pressure of nitrogen gas normalized by the saturated vapor pressure of nitrogen at 77K. The vertical axis shows the volume of the adsorbed nitrogen gas normalized by the weight of the porous coordination polymer (not including the weight of the first ionic liquid).

  According to FIG. 11, as the EMI-TFSI filling rate increases to 0, 25, and 50% with respect to the first pore volume, the nitrogen gas adsorption amount continuously decreases. That is, it is shown that the space in which the nitrogen gas can be adsorbed in the first pore is reduced by the incorporation of EMI-TFSI into the first pore of ZIF-8-nano.

  On the other hand, according to FIG. 12, when the EMI-TFSI filling rate is 25%, the first pore volume is also reduced by about 25%. However, when it becomes 50%, it becomes almost impossible to adsorb nitrogen gas. The cause of this will be described with reference to FIGS.

  As shown in FIG. 2, since the first ionic liquid 3 diffuses through the first pores 21 of the porous coordination polymer very slowly, in the case of coarse particles such as ZIF-8-bulk, It is considered that the first ionic liquid 3 remains in the vicinity of the particle surface. Therefore, when the filling rate is 25%, a large number of empty first pores 21 in which the first ionic liquid 3 does not exist remain in the vicinity of the surface as shown in FIG. Therefore, nitrogen gas can freely access the first pore 21 of the porous coordination polymer, and the volume of the first pore 21 is reduced by the volume of the first ionic liquid 3.

  However, when the filling rate is 50%, all the first pores 21 near the surface of the particles are completely filled with the first ionic liquid 3 as shown in FIG. As described above, since the diffusion of the first ionic liquid 3 is slow, closed first pores 21 in which nitrogen gas cannot be accessed are formed inside the particles. Therefore, nitrogen gas can hardly be adsorbed.

Also, pay attention to the low pressure side of FIGS. In general, adsorption to micropores appears in a low pressure region of 0.1 or less. Comparing the EMI-TFSI filling rate of 0%, ZIF-8-bulk has an adsorption amount of 380 cm ³ / g at a gas pressure of 0.1, but ZIF-8-nano greatly decreases to 344 cm ³ / g. Yes.

  This can be explained with reference to FIGS. The surface of the ZIF-8-bulk particle is considered to be as shown in FIG. It is a smooth surface in which metal ions 23 and organic ligands 24 are regularly arranged. On the other hand, the surface of ZIF-8-nano is considered to be as shown in FIG. Since the surface unevenness is increased, the amount of the first pores 21 formed by the metal ions 23 and the organic ligands 24 per unit weight is reduced. Therefore, in ZIF-8-nano, the gas adsorption amount per weight of the porous coordination polymer decreases as shown in FIG.

In addition, according to FIG. 11, ZIF-8-nano and a sample obtained by combining this with EMI-TFSI adsorb nitrogen gas even at a relative pressure (P / P ₀ ) of 0.2 to 0.95. Hysteresis occurs in the process and desorption process. This is a behavior peculiar to a substance having mesopores. That is, ZIF-8-nano has mesopores (second pores). On the other hand, it can be seen that the ZIF-8-bulk shown in FIG. 12 has only micropores and no mesopores.

  TEM observation was performed, and it was confirmed that ZIF-8-nano was an aggregate having a structure in which nanoparticles were bonded as shown in FIG. The reason why the nanoparticles were bonded together is thought to be that during the synthesis of ZIF-8-nano, the two liquids were mixed and then stirred for 1 hour to gradually bond the particles together.

  FIGS. 13 and 14 show differential scanning calorimetry (DSC) of the obtained composite and EMI-TFSI as a reference example alone. The temperature range is −100 to 200 ° C., and the heating and cooling rates are 5 ° C./min. In addition, since no peak was observed in all samples at 100 to 200 ° C., it was omitted in FIGS.

  As shown in FIG. 13, the composite of ZIF-8-nano and EMI-TFSI does not show any endothermic / exothermic peak at a filling rate of 50 to 100%. That is, EMI-TFSI taken into the first pores of ZIF-8-nano does not show clear melting and solidification. At 125%, minute endothermic and exothermic peaks appear, which are substantially the same temperature as in the case of EMI-TFSI alone as a reference example. That is, the peak appearing when the filling rate is 125% is considered to be derived from melting and solidification of EMI-TFSI remaining outside the ZIF-8-nano particles without completely entering the first pores. .

  On the other hand, in the composite of ZIF-8-bulk and EMI-TFSI shown in FIG. 14, no endothermic / exothermic peak appears when the filling rate is 25 to 50%. This is due to the incorporation of EMI-TFSI into the first pore. However, when the filling rate is increased to 100%, endothermic / exothermic peaks appear. That is, ZIF-8-bulk has less EMI-TFSI that can be taken into the first pore than ZIF-8-nano.

  Among the composites of ZIF-8-bulk and EMI-TFSI, those with a filling rate of 50% do not appear any peaks in DSC, so it is considered that all EMI-TFSI is taken into the first pores. . Moreover, from the result of nitrogen gas adsorption measurement, it is considered that EMI-TFSI stays in the vicinity of the surface of ZIF-8-bulk particles. That is, it is considered that the state is as shown in FIG. In FIG. 15, 100 is a complex of ZIF-8-bulk and EMI-TFSI, S1 is a region filled with EMI-TFSI, and S2 is a region not filled with EMI-TFSI.

  When the average particle size of the primary particles of ZIF-8-bulk is 200 nm and EMI-TFSI diffuses to this state in 25 hours, the diffusion rate of EMI-TFSI is estimated to be approximately 1 nm / h (hour). . As described above, if the heating time is too long at the time of compounding, ZIF-8 is decomposed, so the heating time is limited to 25 hours. Therefore, since the diffusion distance of EMI-TFSI is limited to 25 nm, the average particle size of the primary particles of ZIF-8 must be 50 nm or less.

  Next, the ionic conductivity of the sample was evaluated. FIG. 16 shows the temperature dependence of the ionic conductivity of the complex of ZIF-8-nano and EMI-TFSI. The filling rate is 50, 75, 100%. The sample was press-molded and sandwiched between electrodes made of stainless steel (SUS), and the ionic conductivity was evaluated by an AC impedance method in a dry argon gas atmosphere. The measurement frequency is 1 Hz to 1 MHz.

  As a reference example, the ionic conductivity of EMI-TFSI alone was also evaluated. A Kapton ring (inner diameter 3 mm, thickness 0.1 mm) was placed on the SUS electrode, 1 μL of EMI-TFSI was dropped inside the ring, and another SUS electrode was sandwiched from above. Ionic conductivity was evaluated by AC impedance method in a dry argon gas atmosphere.

  As is clear from FIG. 16, the ionic conductivity increased by 2 digits or more as the filling rate increased by 25%. Since the ionic conductivity is proportional to the amount of carriers, in an ordinary system, the ionic conductivity should be proportional to the filling rate. This abnormal conductivity improvement effect can be explained as follows.

  When the filling rate is as low as 50%, the network of the first ionic liquid in the first pores is frequently interrupted. Therefore, the ionic conductivity is extremely low. On the other hand, when the filling rate is increased to 100%, the network of the first ionic liquid spreads in the first pores without interruption, so that the ionic conductivity is greatly improved.

  In ZIF-8-bulk, since the filling rate is limited to 50%, this improvement in ionic conductivity is an effect of making ZIF-8 nanosized to an average primary particle size of 50 nm or less.

  In the case of EMI-TFSI alone as a reference example, a rapid decrease in ionic conductivity was observed at low temperatures. Since the melting point of EMI-TFSI alone is -17 ° C., this rapid decrease is considered to be due to solidification of EMI-TFSI. On the other hand, in the case of the composite, no discontinuous change was observed in the ionic conductivity. Furthermore, the composite with a filling rate of 100% showed higher ionic conductivity than EMI-TFSI alone at a low temperature. Even if the temperature is such that EMI-TFSI alone solidifies and does not exhibit ionic conductivity, the composite does not cause a clear phase transition of EMI-TFSI and is always kept in a liquid state. That is, the composite can be made EMI-TFSI at a low temperature by two synergistic effects, that is, the effect of improving the filling ratio of EMI-TFSI by nano-size ZIF-8 and the effect that EMI-TFSI always maintains a liquid state. It showed higher ionic conductivity than the single case.

[Example 2]
<In case of ionic liquid showing plastic crystal phase>
Evaluation was also performed when N-ethyl-N-methylpyrrolidinium bis (trifluoromethanesulfonyl) imide (hereinafter referred to as Py ₁₂ TFSI), which is a pyrrolidinium salt, was used as the ionic liquid. Py ₁₂ TFSI shows a plastic crystal phase at room temperature. When Py ₁₂ TFSI alone was press-molded and the ionic conductivity was evaluated in the same manner as in Example 1, it was 1 × 10 ⁻⁷ S / cm at room temperature (23 ° C.).

Evaluation was also performed when Py ₁₂ TFSI was combined with ZIF-8-nano. The filling rate is 100%, and the composite method is the same as in the case of EMI-TFSI. This composite exhibited an ionic conductivity of 8 × 10 ⁻⁷ S / cm at room temperature (23 ° C.). That is, when combined with ZIF-8-nano, the ionic conductivity was improved as compared with the case of Py ₁₂ TFSI alone.

On the other hand, the ionic conductivity of the composite of ZIF-8-nano and EMI-TFSI (filling rate 100%) was 4 × 10 ⁻⁷ S / cm at room temperature (23 ° C.). The ionic conductivity of EMI-TFSI alone is 2 × 10 ⁻² S / cm according to the literature (S. Seki et al., J. Phys. Chem. B, 2006, 110 (21), 10228). . That is, when combined with ZIF-8-nano, the ionic conductivity was reduced by almost three orders of magnitude compared to the case of EMI-TFSI alone.

  From the above results, high ionic conductivity was obtained by combining porous coordination polymer nanoparticles and an ionic liquid exhibiting a plastic crystal phase.

  When an ionic liquid exhibiting a plastic crystal phase is introduced into the first pores of the porous coordination polymer nanoparticles, the ionic liquid in the first pores forms a plastic crystal phase having a disordered structure. . That is, since defects are introduced at a high density, ion hopping conduction is facilitated. In addition, since the porous coordination polymer is made into nanoparticles, the ionic liquid can be filled with high density. Due to these two effects, it is considered that when the ionic liquid showing the plastic crystal phase is combined with the porous coordination polymer, the ionic conductivity is increased.

[Example 3]
<When an organic solvent is added>
Put the complex of ZIF-8-nano and EMI-TFSI (filling rate 50%) in a container without a lid, put ethyl carbitol in a container without a lid, put them in the same container and close the lid. Sealed. By leaving it in this state for 12 hours, vapor of ethyl carbitol was sucked into the composite to obtain a composite containing an organic solvent.

  When this composite was press-molded and the ionic conductivity was evaluated in the same manner as in Example 1, the result shown in FIG. 17A was obtained. The ionic conductivity before complexing with ethyl carbitol is shown in FIG. That is, by combining with ethyl carbitol, the ionic conductivity could be increased by about 4 digits.

  From the above results, it can be seen that the composite may contain an organic solvent. When the organic solvent is dissolved in the ionic liquid, the degree of dissociation of the ionic liquid is improved, and the ionic conductivity is improved. This is presumably because the organic solvent coordinated with the ions constituting the ionic liquid to form a solvate and facilitated the dissociation of the cation and the anion.

[Example 4]
<When lithium salt is added>
As an ionic liquid, a mixture of EMI-TFSI and lithium bis (trifluoromethanesulfonyl) imide (hereinafter sometimes referred to as LiTFSI) at a molar ratio of 8: 2 (hereinafter referred to as (EMI _0.8 Li _0.2 ) TFSI) In some cases, evaluation was also performed. The ratio of lithium ions to cations in (EMI _0.8 Li _0.2 ) TFSI is 20% in molar ratio.

With respect to the first pore volume of ZIF-8-nano, the pore volume of ZIF-8 was 0.64 cm ³ / g and the density of (EMI _0.8 Li _0.2 ) TFSI was 1.52 g / cm ³ . The ratio was such that the volume occupancy of one ionic liquid was 100%. The ionic conductivity was evaluated in the same manner as in Example 1. As a reference example, the ion conductivity of (EMI _0.8 Li _0.2 ) TFSI alone was also evaluated. The evaluation method is the same as in the case of EMI-TFSI alone.

The evaluation results of ionic conductivity are shown in FIG. In the case of (EMI _0.8 Li _0.2 ) TFSI alone, which is a reference example, a rapid decrease in ionic conductivity was observed at low temperatures. (EMI _0.8 Li _0.2 ) TFSI alone causes a glass transition at −81 ° C. That is, the rapid decrease in ionic conductivity is thought to be due to vitrification of (EMI _0.8 Li _0.2 ) TFSI. On the other hand, the ionic conductivity of the composite did not change rapidly even at low temperatures. This is probably because (EMI _0.8 Li _0.2 ) TFSI does not have a clear phase transition in the composite and always maintains a liquid state. Since the composite has a small change in ionic conductivity due to temperature, it can be used as an ionic conductor in a wider temperature range.

Further, the diffusion coefficient of lithium ions was evaluated by pulse magnetic field gradient NMR measurement. The sample was enclosed in Pyrex (registered trademark) glass under a dry argon atmosphere. The measurement was performed on ⁷ Li nuclei at a magnetic field of 9.4 T and a frequency of 155.5 MHz. The pulse sequence used was a stimulated-echo pulse sequence (see, for example, Tanner, JE, J. Chem. Phys. 1970, 52, 2523.). The application time of the pulse magnetic field gradient is 1 millisecond, and the interval between the two pulse magnetic field gradients is 40 milliseconds.

The diffusion coefficient of (EMI _0.8 Li _0.2 ) TFSI alone was 8.0 × 10 ⁻¹² m ² / s at 300 ° C., and the composite was 1.8 × 10 ⁻¹² m ² / s at 350 ° C. ZIF-8 has a structure in which pores having a diameter of 12 mm are three-dimensionally connected through openings having a diameter of 3 mm. Despite the fact that lithium ions are confined in this pore network, the diffusion coefficient of the same order as (EMI _0.8 Li _0.2 ) TFSI alone is due to the interaction between lithium ions and anions of ZIF-8. This is thought to be because it was weakened by the interaction with the inner wall, and lithium ions could move so as to jump between the anions. Furthermore, since the size of lithium ions is small, it is considered that it can move smoothly in the pores of ZIF-8.

DESCRIPTION OF SYMBOLS 1A-1C Ion conductive composite 2 Porous coordination polymer nanoparticle 21 1st pore 22 Concavity and convexity 23 Metal ion 24 Organic ligand 3 1st ionic liquid 4 2nd pore 5 Ion conductive substance 6 Gap 100 ZIF-8-bulk and EMI-TFSI complex S1 Region filled with EMI-TFSI S2 Region not filled with EMI-TFSI

Claims (18)

Crystal particles of porous coordination polymer having an average primary particle size of 50 nm or less;
An ion conductive composite comprising: a first ionic liquid held in a first pore of the porous coordination polymer.   The ion conductive composite according to claim 1, wherein the first ionic liquid contains lithium.   The ion conductive composite according to claim 1, wherein the first ionic liquid exhibits a plastic crystal phase.   The ion conductive composite according to claim 1, further comprising an organic solvent in the first pore.   The ion conductive composite according to claim 1, wherein the surface of the crystal particles has irregularities. A plurality of the crystal particles constitute an aggregate including second pores provided between the crystal particles by partially bonding the crystal particles adjacent to each other,
6. The ion conductive composite according to claim 1, wherein an average pore diameter of the second pore is larger than an average pore diameter of the first pore.   The ion conductive composite according to claim 6, wherein the first pore is a micropore, and the second pore is a mesopore.   The ion conductive composite according to claim 6, wherein the second ionic liquid is contained in the second pore.   The ion conductive composite according to any one of claims 6 to 8, wherein an organic solvent is contained in the second pores.   An organic solvent is further contained in the first pore, and the organic solvent contained in the second pore is the same as the organic solvent contained in the first pore. The ion conductive composite according to claim 9, wherein   The ion conductive composite according to any one of claims 1 to 5, wherein the ion conductive composite is a structure that is formed by a plurality of crystal grains and includes a gap provided between the crystal grains.   The structure is formed by at least one of the plurality of crystal grains and the aggregate, and has a gap provided between at least one of the crystal grains and between the aggregates. Item 11. The ion conductive composite according to any one of Items 6 to 10.   The ion conductive composite according to claim 11 or 12, wherein the structure is in the form of a film or a sheet.   The ion conductive composite according to claim 11, wherein the structure has an ion conductive material in the gap.   The ion conductive composite according to claim 14, wherein the ion conductive material contains a second ionic liquid.   The ion conductive composite according to claim 15, wherein the second ionic liquid is the same as the first ionic liquid.   The ion conductive composite according to claim 14, wherein the ion conductive material contains an organic solvent.   At least one of the first pore and the second pore contains an organic solvent, and the organic solvent contained in the ion conductive material includes the organic solvent contained in the at least one The ion conductive composite according to claim 17, which is the same.

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