Ion conductor comprising a high-temperature phase of LiCB9H 10 and a method of manufacturing the same

Abstract

According to the present application, it is possible to provide a method for producing an ion conductor including LiCB9H 10 and LiCB 11 H 12 , the method for producing an ion conductor including: a solutionizing step of mixing LiCB9H 10 and LiCB 11 H 12 in a solvent at a molar ratio of LiCB9H 10 / LiCB 11 H 12 = 1.1 to 20 to prepare a homogeneous solution; a drying step of removing the solvent from the homogeneous solution to obtain a precursor; and a heat treatment step of subjecting the precursor to a heat treatment to obtain an ion conductor.

Description

TECHNICAL FIELD

[0001] The present application relates to an ion conductor comprising a high-temperature phase of LiCB9H 10 and a manufacturing method thereof. BACKGROUND

[0002] In recent years, the demand for lithium ion secondary batteries has increased in applications such as portable information terminals, portable electronic devices, electric vehicles, hybrid electric vehicles, and stationary power storage systems. However, current lithium ion secondary batteries use flammable organic solvents as electrolytes, and require robust outer packaging to prevent leakage of the organic solvents. In addition, in portable personal computers and the like, structures to prevent risks in the event of electrolyte leakage are required, and there are limitations on the structure of the device.

[0003] Furthermore, its applications have expanded to mobile bodies such as automobiles and aircraft, and large capacity is required in stationary lithium ion secondary batteries. Under such circumstances, there is a tendency to place greater emphasis on safety than in the past, and development of all-solid lithium ion secondary batteries that do not use harmful substances such as organic solvents is being pursued.

[0004] For example, oxides, phosphoric acid compounds, organic polymers, sulfides, complex hydrides, and the like are being studied as solid electrolytes in all-solid lithium ion secondary batteries.

[0005] All-solid batteries are roughly classified into thin film type and bulk type. With regard to the thin film type, although interfaces are desirably formed by vapor deposition, the electrode layer is as thin as several μm, the electrode area is small, the energy that can be stored in each single cell is small, and the cost is high. Therefore, it is not suitable as a battery for large-scale power storage devices or electric vehicles that require storage of a large amount of energy. On the other hand, the thickness of the electrode layer of the bulk type can be several tens of μm to 100 μm, and an all-solid battery having a high energy density can be produced.

[0006] Among solid electrolytes, sulfides and complex hydrides have high ionic conductivity and are relatively soft, and thus have the characteristic of easily forming interfaces between solids, and research on bulk-type all-solid batteries is being pursued (Patent Documents 1 and 2).

[0007] However, existing sulfide solid electrolytes have the property of reacting with water, and hydrogen sulfide is generated from the sulfide, and there is a problem of a decrease in ionic conductivity after reaction with moisture. On the other hand, complex hydride solid electrolytes have a tendency to have slightly lower ionic conductivity than sulfide solid electrolytes, and improvement in ionic conductivity is desired.

[0008] A solid electrolyte called carborane (6.7 mS / cm at 25°C) having high ionic conductivity is described in Non-Patent Literature 1, but a mechanical grinding method is used. The mechanical grinding method has problems in terms of mass production, and a mass synthesis method using a solution is desired. On the other hand, Non-Patent Literature 2 discloses a method in which a solid electrolyte solution in which a hydridoboron compound as a solid electrolyte is dissolved is applied to the fitting surface of the positive electrode layer and the negative electrode layer of an electrode, and then the solvent is removed and laminated, and a low pressure is applied, whereby a full solid battery having excellent productivity is manufactured.

[0009] In Non-Patent Literature 3, a solid electrolyte called carborane having high ionic conductivity (5 mS / cm at 35°C) is synthesized using an aqueous solvent, but not only a high-temperature phase of LiCB9H 10 , but also a complex phase of LiCB9H 10 and LiCB 11 H 12 is formed. In addition, further improvement of ionic conductivity is desired.

[0010] Prior Art Documents

[0011] Patent Documents

[0012] Patent Document 1: Japanese Patent 6246816

[0013] Patent Document 2: WO2017-126416

[0014] Non-Patent Literature

[0015] Non-Patent Literature 1: Nature Communications volume 10, Article number: 1081 (2019)

[0016] Non-Patent Literature 2: 59th Battery Symposium 3B04 Development of all-solid-state lithium battery using hydride-based solid electrolyte and battery characteristics thereof

[0017] Non-Patent Literature 3: ACS Energy Lett. 2016, 1, 659-664 SUMMARY

[0018] PROBLEMS TO BE SOLVED BY THE INVENTION

[0019] An object of the present application is to provide an ion conductor having excellent various properties such as ion conductivity and a method for producing the same.

[0020] TECHNICAL SOLUTION FOR SOLVING THE PROBLEMS

[0021] The present inventors have conducted intensive studies in order to solve the above-described technical problems, and as a result, have found that an ionic conductor obtained by using a homogeneous solution prepared by mixing LiCB9H 10 and LiCB 11 H 12 in a solvent at a specific molar ratio is capable of solving the above-described technical problems. That is, the present application is as described below.

[0022] <1> A production method of an ionic conductor containing LiCB9H 10 and LiCB 11 H 12 , the production method comprising:

[0023] a solutionizing step of mixing LiCB9H 10 and LiCB 11 H 12 in a solvent at a molar ratio of LiCB9H 10 / LiCB 11 H 12 = 1.1 to 20 to prepare a homogeneous solution;

[0024] a drying step of removing the solvent from the homogeneous solution to obtain a precursor; and

[0025] a heat treatment step of subjecting the precursor to a heat treatment to obtain the ionic conductor.

[0026] <2> The production method of the ionic conductor according to <1> described above, wherein the solvent in the solutionizing step is at least one selected from the group consisting of water, tetrahydrofuran, acetonitrile, acetone, ethyl acetate, methyl acetate, toluene, dichloromethane, and trichloromethane.

[0027] <3> The production method of the ionic conductor according to <1> described above, wherein the solvent in the solutionizing step consists of water.

[0028] <4> The production method of the ionic conductor according to any one of <1> to <3> described above, wherein the stirring and mixing time in the solutionizing step is 5 minutes to 48 hours.

[0029] <5> The production method of the ionic conductor according to any one of <1> to <4> described above, wherein the molar ratio of LiCB9H 10 to LiCB 11 H 12 in the solutionizing step is LiCB9H 10 / LiCB 11 H 12 = 1.5 to 9.

[0030] The manufacturing method of the ion conductor according to any one of the above <1> to <5>, wherein the temperature in the drying step is 50 to 260°C.

[0031] The manufacturing method of the ion conductor according to any one of the above <1> to <6>, wherein the drying time in the drying step is 1 to 24 hours.

[0032] The manufacturing method of the ion conductor according to any one of the above <1> to <7>, wherein the temperature in the heat treatment step is 150 to 260°C.

[0033] The manufacturing method of the ion conductor according to any one of the above <1> to <8>, wherein the heat treatment time in the heat treatment step is 1 to 24 hours.

[0034] The manufacturing method of the ion conductor according to any one of the above <1> to <9>, wherein the obtained ion conductor has a single-phase crystal structure of a high-temperature phase of LiCB9H 10 .

[0035] The manufacturing method of the ion conductor according to any one of the above <1> to <10>, wherein the obtained ion conductor has X-ray diffraction peaks at least at 2θ = 14.9 ± 0.3 deg, 16.4 ± 0.3 deg, 17.1 ± 0.5 deg in X-ray diffraction measurement at 25°C, and the intensity ratio (B / A) calculated from A = (X-ray diffraction intensity at 16.4 ± 0.3 deg) - (X-ray diffraction intensity at 20 deg), B = (X-ray diffraction intensity at 17.1 ± 0.5 deg) - (X-ray diffraction intensity at 20 deg) is 1.0 to 20.

[0036] The manufacturing method of the ion conductor according to any one of the above <1> to <11>, wherein the obtained ion conductor has an ion conductivity of 1.0 to 10 mScm -1 at 25°C.

[0037] The ion conductor obtained by the manufacturing method of the ion conductor according to any one of the above <1> to <12>.

[0038] The electrode using the ion conductor according to the above <13>.

[0039] The all-solid-state battery using the ion conductor according to the above <13>.

[0040] Effects of the Invention

[0041] According to the present application, an ion conductor having excellent various properties such as ion conductivity and a manufacturing method thereof can be provided. BRIEF DESCRIPTION OF DRAWINGS

[0042] Figure 1 X-ray diffraction peaks in a powder of the ion conductor obtained in Example 1 are shown.

[0043] Figure 2 Raman spectrum of the ion conductor obtained in Example 1 is shown.

[0044] Figure 3 Measurement results of ion conductivity of the ion conductor obtained in Example 1 are shown.

[0045] Figure 4 Measurement results of differential thermal analysis (DTA) of the ion conductor obtained in Example 1 are shown. DETAILED DESCRIPTION

[0046] Hereinafter, an embodiment of the present application will be described. The materials, configurations, and the like described below are not limiting of the present application, and various changes can be made within the scope of the gist of the present application.

[0047] 1. Ion conductor

[0048] According to one embodiment of the present application, an ion conductor containing lithium (Li), carbon (C), boron (B), and hydrogen (H) is provided. The above embodiment preferably contains, as a crystal, a high-temperature phase (high-ion-conducting phase) of LiCB9H 10 , more preferably contains, as a crystal, a high-temperature phase (high-ion-conducting phase) of LiCB9H 10 , and is composed of LiCB9H 10 and LiCB 11 H 12 .

[0049] The ion conductor of the present application preferably has peaks at 749 cm 10 (±5 cm -1 ) based on LiCB9H -1 and 763 cm 11 (±5 cm 12 ) based on LiCB -1 H -1 , respectively, in Raman spectroscopic measurement. Peaks can be present in other regions as well, but the peaks indicating respective characteristics are the above peaks.

[0050] The ion conductor of the present application preferably contains, as a crystal, a high-temperature phase of LiCB9H 10 . LiCB9H 10Due to its crystalline state, it has a high-temperature phase and a low-temperature phase. The high-temperature phase has high ionic conductivity at higher temperatures (e.g., around 75–150°C), but becomes a low-temperature phase near room temperature (e.g., around 20–65°C), where the ionic conductivity decreases.

[0051] In X-ray diffraction measurements of the ionic conductor of the present invention at 25°C, it is preferred to have a LiCB9H-based structure at least at 2θ = 14.9 ± 0.3 deg, 16.4 ± 0.3 deg, and 17.1 ± 0.5 deg. 10 The X-ray diffraction peaks of the high-temperature phase. More preferably, the intensity ratio (B / A) calculated from A = (X-ray diffraction intensity of 16.4 ± 0.3 degrees) - (X-ray diffraction intensity of 20 degrees) and B = (X-ray diffraction intensity of 17.1 ± 0.5 degrees) - (X-ray diffraction intensity of 20 degrees) is in the range of 1.0 to 20, further preferably in the range of 1.0 to 15, and particularly preferably in the range of 1.0 to 10. When the intensity ratio (B / A) is in the range of 1.0 to 20, by using LiCB9H 10 LiCB solid solution in high temperature phase 11 H 12 The phase transition temperature decreases, allowing it to maintain high ionic conductivity even near room temperature. This solid solution in LiCB9H... 10 / LiCB 11 H 12 This condition holds true when the molar ratio is 1.1 or higher. LiCB9H is preferred. 10 / LiCB 11 H 12 =1.1~20, more preferably LiCB9H 10 / LiCB 11 H 12 =1.25~10, with LiCB9H being particularly preferred. 10 / LiCB 11 H 12 =1.5 to 9, which is a value with high ionic conductivity.

[0052] Even if the ion conductor of the present invention contains X-ray diffraction peaks other than those mentioned above, the desired effect can still be obtained.

[0053] Furthermore, the ionic conductor of the present invention may also contain components other than lithium (Li), carbon (C), boron (B), and hydrogen (H). Other components may include, for example, oxygen (O), nitrogen (N), sulfur (S), fluorine (F), chlorine (Cl), bromine (Br), iodine (I), silicon (Si), germanium (Ge), phosphorus (P), alkali metals, and alkaline earth metals.

[0054] The ion conductor described above is flexible and can be formed into an electrode layer and a solid electrolyte layer by a cold press. Furthermore, the electrode layer and the solid electrolyte layer thus formed are excellent in strength compared with a case where a large amount of a sulfide solid electrolyte or an oxide solid electrolyte is contained. Therefore, by using the ion conductor of the present application, an electrode layer and a solid electrolyte layer which are excellent in formability and less likely to be broken (less likely to be cracked) can be produced. In addition, the ion conductor of the present application has a low density, and therefore an electrode layer and a solid electrolyte layer which are relatively light can be produced. Thus, the weight of the entire battery can be reduced, which is preferable. Furthermore, in the case where the ion conductor of the present application is used in a solid electrolyte layer, the interfacial resistance with an electrode layer can be reduced.

[0055] Further, the ion conductor described above is not decomposed even when it is brought into contact with moisture or oxygen, and does not generate a dangerous toxic gas.

[0056] The ion conductivity of the ion conductor of the present application at 25°C is preferably 1.0 to 10 mScm -1 , more preferably 2.0 to 10 mScm -1 .

[0057] 2. Method for producing an ion conductor

[0058] According to another embodiment of the present application, there is provided a method for producing an ion conductor containing LiCB9H 10 and LiCB 11 H 12 , which comprises: a solutionizing step of mixing LiCB9H 10 and LiCB 11 H 12 in a solvent at a molar ratio of LiCB9H 10 / LiCB 11 H 12 = 1.1 to 20 to prepare a homogeneous solution; a drying step of removing the solvent from the homogeneous solution to obtain a precursor; and a heat treatment step of subjecting the precursor to a heat treatment to obtain the ion conductor.

[0059] In the present application, "a homogeneous solution" is defined as a solution in which at least lithium (Li), carbon (C), boron (B), and hydrogen (H) are contained in a solvent, there is no undissolved precipitate, and the raw materials are dissolved in the solvent.

[0060] As the raw materials, LiCB9H 10 and LiCB 11 H 12 , generally commercially available products can be used. In addition, the purity thereof is preferably 95% or more, more preferably 98% or more. By using a compound having a purity in the above range, a desired crystal is easily obtained.

[0061] LiCB9H 10 With LiCB 11 H 12 The mixing ratio needs to be LiCB9H 10 / LiCB 11 H 12 A molar ratio of 1.1 or higher is preferred. LiCB9H is preferred. 10 / LiCB 11 H 12 =1.1~20, more preferably LiCB9H 10 / LiCB 11 H 12 =1.25~10, with LiCB9H being particularly preferred. 10 / LiCB 11 H 12 =1.5 to 9. As mentioned above, the ionic conductivity exhibits particularly high values ​​within this range.

[0062] LiCB9H 10 With LiCB 11 H 12 The mixture can be mixed in the atmosphere with a homogeneous solvent.

[0063] As a mixing method, it can also be carried out in a solvent. There are no particular limitations on the solvent, and examples include water, nitrile solvents mainly composed of acetonitrile, ether solvents such as tetrahydrofuran and diethyl ether, N,N-dimethylformamide, N,N-dimethylacetamide, alcohol solvents such as methanol and ethanol, acetone, ethyl acetate, methyl acetate, toluene, dichloromethane, and chloroform. Among these solvents, water is particularly preferred for safety reasons.

[0064] The mixing time in the solvent varies depending on the mixing method. In the case of stirring and mixing in the solvent, it is preferred to be 5 minutes to 48 hours, and more preferably 5 minutes to 1 hour.

[0065] The pressure used in the solution process is typically in the range of 0.1 Pa to 2 MPa absolute pressure. Preferably, it is 101 kPa to 1 MPa.

[0066] The solution-forming process is preferably carried out in an inert gas atmosphere or in a sufficiently dry atmosphere. There are no particular limitations on the inert gas, but argon is particularly preferred.

[0067] The drying temperature of the solvent in the drying process is typically in the range of 50–300°C. Preferably, it is 50–260°C, and more preferably 150–220°C.

[0068] In addition, the drying time of the solvent in the drying step is slightly different depending on the kind of the solvent and the drying temperature, but the solvent can be sufficiently removed by performing for 1 to 24 hours. The drying time of the solvent is more preferably 10 to 14 hours. Among them, by removing the solvent under reduced pressure, such as vacuum drying, circulating a non-active gas such as nitrogen, argon, and the like in which the moisture is sufficiently small, the temperature at the time of removing the solvent can be reduced and the required time can be shortened. Among them, the heating treatment step and the drying step of the later stage can be performed simultaneously.

[0069] The reduced pressure condition of the solvent in the drying step is usually 10 -1 Pa or less. It is preferably 5 x 10 -4 Pa or less.

[0070] In the heating treatment step, the precursor obtained in the drying step is subjected to heating treatment to obtain an ion conductor.

[0071] The heating temperature is preferably in the range of 150 to 260°C, and more preferably in the range of 180 to 220°C. When the temperature is lower than the above range, it is difficult to produce the desired crystal, on the other hand, even if the temperature is higher than the above range, sometimes crystals other than the target are generated.

[0072] The heating time, although it slightly varies depending on the heating temperature, can be usually in the range of 1 to 24 hours to sufficiently crystallize. When heating at a higher temperature for a long time exceeding the above range, the ion conductor can be deteriorated, and thus it is not preferable. The more preferable heating time is in the range of 10 to 14 hours.

[0073] The heating can be performed under vacuum to 1 MPa or under a non-active gas atmosphere, and it is preferably performed under vacuum. As the non-active gas, nitrogen, helium, argon, and the like can be used, and among them, argon is preferable. In the present application, instead of vacuum, heating treatment can be performed under an argon atmosphere at 1 MPa, for example. It is preferable to be low in oxygen and moisture.

[0074] The ion conductor obtained by the above production method of the present application has a peak at 749 cm 10 (±5 cm -1 ) based on LiCB9H -1 and 763 cm 11 (±5 cm 12 ) based on LiCB -1 H -1 , respectively, in Raman spectroscopy. In addition, in the X-ray diffraction measurement at 25°C, at least 2θ = 14.9 ± 0.3 deg, 16.4 ± 0.3 deg, 17.1 ± 0.5 deg based on LiCB9H 10The intensity ratio (B / A) calculated from the X-ray diffraction intensities of A = (16.4 ± 0.3 deg of X-ray diffraction intensity) - (20 deg of X-ray diffraction intensity), B = (17.1 ± 0.5 deg of X-ray diffraction intensity) - (20 deg of X-ray diffraction intensity) of the high-temperature phase of the above-mentioned X-ray diffraction peak is preferably in the range of 1 to 20, more preferably in the range of 1.0 to 15, and particularly preferably in the range of 1.0 to 10.

[0075] 3. All-solid battery

[0076] The ion conductor of the present application can be used as a solid electrolyte for an all-solid battery. Therefore, according to one embodiment of the present application, a solid electrolyte for an all-solid battery comprising the above-mentioned ion conductor is provided. In addition, according to a further embodiment of the present application, an all-solid battery using the above-mentioned solid electrolyte for an all-solid battery is provided.

[0077] In the present specification, the all-solid battery refers to a lithium ion responsible all-solid battery, and particularly an all-solid lithium ion secondary battery. The all-solid battery has a structure in which a solid electrolyte layer is disposed between a positive electrode layer and a negative electrode layer. The ion conductor of the present application can be contained in any one or more of the positive electrode layer, the negative electrode layer, and the solid electrolyte layer as a solid electrolyte. In the case of use for an electrode layer, use for the negative electrode layer is preferred compared to use for the positive electrode layer. This is because the negative electrode layer is more difficult to undergo a side reaction. In the case where the ion conductor of the present application is contained in the positive electrode layer or the negative electrode layer, the ion conductor is used in combination with a known positive electrode active material or negative electrode active material for a lithium ion secondary battery. As the negative electrode layer, if a bulk type in which an active material is mixed with a solid electrolyte is used, the capacity of each single cell becomes large, and thus is preferred.

[0078] The all-solid battery is produced by forming and laminating the above-mentioned layers, but the method of forming and the method of laminating each layer are not particularly limited. For example, there are a method in which a material in which a solid electrolyte and / or an electrode active material is dispersed in a solvent is formed into a paste-like material by a doctor blade, spin coating, or the like, and film formation is performed by calendering; a vapor phase method in which film formation and lamination are performed using a vacuum evaporation method, an ion plating method, a sputtering method, a laser ablation method, or the like; a press method in which a powder is formed by a hot press or a cold press to which no temperature is applied, and lamination is performed; and the like. The ion conductor of the present application is relatively soft, and thus it is particularly preferred that the battery be produced by forming and laminating by pressing. In addition, it is also possible to previously form an electrode layer to which an active material, a conductive aid, a binder, or the like is added, to flow a solution obtained by dissolving a solid electrolyte in a solvent or a slurry obtained by dispersing a solid electrolyte in a solvent into the electrode layer, and then to remove the solvent, thereby adding the solid electrolyte into the electrode layer.

[0079] As an atmosphere in which the all-solid battery is produced, it is preferable to be performed in a non-reactive gas or a dry chamber in which moisture is managed. As the moisture management, it is more preferable to be in a range of dew point -10°C to -100°C, particularly preferably in a range of dew point -20°C to -80°C, and especially preferably in a range of dew point -30°C to -75°C. This is to prevent a case where, although the hydrolysis rate of the ion conductor of the present application is extremely slow, the ionic conductivity is decreased due to formation of hydrates.

[0080] Example

[0081] Hereinafter, the present application will be described in detail by examples, but the content of the present application is not limited to this.

[0082] Preparation of Ion Conductor

[0083] (Example 1)

[0084] In a glove box under argon atmosphere, 240 mg of LiCB9H 10 (Katchem Corporation), 122.2 mg of LiCB 11 H 12 (Katchem Corporation) were weighed so as to be in a molar ratio of LiCB9H 10 : LiCB 11 H 12 = 7:3. Then, 10 mL of pure water (Water, Reagent, Alfa Aesar) was added to the mixed powder of LiCB9H 10 and LiCB 11 H 12 weighed in advance so as to be dissolved, and stirred using a stirrer for 30 minutes. The resulting uniform solution was dried in a glass tube oven under a reduced pressure of 0.1 Pa or less at 150°C for 12 hours, whereby the pure water was removed, and a dried white powder (precursor) was obtained. The obtained white powder was kneaded with a mortar for 15 minutes, and 50 mg thereof was pelletized at 240 MPa, and vacuum heat-treated at 200°C for 12 hours using a turbo pump. The obtained ion conductor was subjected to an alternating current impedance method measurement, and the ionic conductivity was measured. As a result of X-ray diffraction, the high-temperature phase of LiCB9H 10 of the obtained ion conductor became stable. In the DTA measurement, no phase transition was observed, and the Raman spectrum also exhibited the same spectrum as that of the one produced by ball-milling synthesis.

[0085] (Comparative Example 1)

[0086] In Example 1, 240 mg of LiCB9H 10 , 122.2 mg of LiCB 11 H 12The raw materials were used in a molar ratio of 5:5, and the ionic conductor was otherwise manufactured in the same manner as in Example 1.

[0087] <X-ray Diffraction Measurement>

[0088] The ionic conductor powder obtained in Example 1 was subjected to X-ray diffraction (X'pertPro, CuKα) measurements using a Lindemann glass capillary (0.5 mm outer diameter, 0.01 mm thickness) at room temperature (25 °C) under an argon atmosphere. The obtained X-ray diffraction peaks are represented in... Figure 1 In the middle. For comparison, Figure 1 It also indicates that LiCB9H is used as a raw material. 10 LiCB 11 H 12 and LiCB9H 10 X-ray diffraction peaks (at a high temperature of 150℃).

[0089] In Example 1, X-ray diffraction peaks were observed at at least 2θ = 14.9 ± 0.3 degrees, 16.4 ± 0.3 degrees, and 17.1 ± 0.5 degrees. Furthermore, LiCB9H will be used as the reference material. 10 The intensities at the peak positions of the high-temperature phase, 16.44 degrees, and 17.07 degrees are designated as A and B, respectively. The value of 2θ = 20 degrees is considered as the baseline, and the intensities are calculated using A = (X-ray diffraction intensity at 16.44 degrees) - (X-ray diffraction intensity at 20 degrees) and B = (X-ray diffraction intensity at 17.07 degrees) - (X-ray diffraction intensity at 20 degrees).

[0090] Example 1 due to LiCB9H 10 The peak positions of the high-temperature phase are consistent, therefore it can be known that it is a solid solution.

[0091] <Raman Spectrophotometry>

[0092] (1) Sample preparation

[0093] The sample was prepared using a sealed container with a quartz glass (Φ60mm, 1mm thick) as an optical window at the top. The sample was kept liquid in contact with the quartz glass in a glove box under an argon atmosphere. The container was then sealed and removed from the glove box for Raman spectrophotometry.

[0094] (2) Measurement conditions

[0095] Using a laser Raman spectrophotometer NRS-5100 (manufactured by JASCO Corporation), the measurement was performed with an excitation wavelength of 532.15 nm and an exposure time of 5 seconds. The obtained Raman spectrum is shown in Figure 2 .

[0096] LiCB9H 10 at 749 cm -1 -1, LiCB 11 H 12 at 763 cm -1 -1. Among them, the Raman shift value is derived from the combination and is hardly affected by the crystalline state. It is known that the peak at 763 cm -1 in Example 1 is a shoulder peak of the peak at 749 cm -1 .

[0097] < Ion conductivity measurement >

[0098] In an argon atmosphere glove box, the ion conductor obtained in Example 1, LiCB9H 10 and LiCB 11 H 12 as raw materials were subjected to uniaxial molding (240 MPa) to produce a disk having a thickness of about 1 mm, The temperature was raised and lowered at 10°C intervals in the temperature range from room temperature to 150°C or 80°C, and the alternating current impedance measurement based on the two-terminal method (HIOKI 3532-80, chemical impedance meter) using a lithium electrode was performed, and the ion conductivity was calculated. The measurement frequency range was 4 Hz to 1 MHz, and the amplitude was 100 mV.

[0099] The results of the measurement of the respective ion conductivities are shown in Figure 3 . In addition, the ion conductivities at room temperature (25°C) and the activation energies are shown in Table 1. Among them, the phenomenon of sharp decrease in ion conductivity at low temperature, which is observed in LiCB9H 10 and LiCB 11 H 12 as raw materials, was not observed in Example 1. In addition, the ion conductivity of the ion conductor obtained in Comparative Example 1 is shown in Table 1.

[0100] Table 1 Ion conductivities at 25°C and activation energies

[0101] Example 1 Comparative Example 1 Ionic conductivity / mScm -1 ]] 5.6 0.8 Activation energy / kJ mol -1 ]] 28.8 -

[0102] < Differential thermal analysis DTA measurement >

[0103] For the powder of the ion conductor obtained in Example 1, differential thermal analysis DTA measurement was performed using a differential thermal analysis DTA device (Rigaku Thermo Plus TG-8120 system) under an argon atmosphere under conditions of from room temperature to 200°C and a temperature increase / decrease rate of 5°C / min. In this case, in Example 1, no phase transition was observed in LiCB9H10 and LiCB11H10, which were raw materials, and the like. Example 2 10 Example 3 11 Example 4 12 Example 5

Claims

1. A method for manufacturing an ionic conductor, wherein the ionic conductor comprises LiCB9H 10 and LiCB 11 H 12 The method for manufacturing the ionic conductor is characterized by comprising: LiCB9H 10 and LiCB 11 H 12 With LiCB9H 10 / LiCB 11 H 12 A solution preparation process in which a homogeneous solution is prepared by mixing in a solvent at a molar ratio of 1.1 to 20. The drying process of removing the solvent from the homogeneous solution to obtain the precursor; and A heat treatment process for obtaining an ionic conductor by heating the precursor.

2. The method for manufacturing an ionic conductor as described in claim 1, characterized in that: The solvent used in the solution-forming process is selected from at least one of water, tetrahydrofuran, acetonitrile, acetone, ethyl acetate, methyl acetate, toluene, dichloromethane, and chloroform.

3. The method for manufacturing an ionic conductor as described in claim 1, characterized in that: The solvent used in the solution treatment process is water.

4. The method for manufacturing an ionic conductor according to any one of claims 1 to 3, characterized in that: The stirring and mixing time in the solution-forming process is from 5 minutes to 48 hours.

5. The method for manufacturing an ionic conductor according to any one of claims 1 to 3, characterized in that: LiCB9H in the solution treatment process 10 With LiCB 11 H 12 The molar ratio is LiCB9H 10 / LiCB 11 H 12 =1.5~9.

6. The method for manufacturing an ionic conductor according to any one of claims 1 to 3, characterized in that: The temperature in the drying process is 50–260°C.

7. The method for manufacturing an ionic conductor according to any one of claims 1 to 3, characterized in that: The drying time in the drying process is 1 to 24 hours.

8. The method for manufacturing an ionic conductor according to any one of claims 1 to 3, characterized in that: The temperature in the heat treatment process is 150–260°C.

9. The method for manufacturing an ionic conductor according to any one of claims 1 to 3, characterized in that: The heating time in the heat treatment process is 1 to 24 hours.

10. The method for manufacturing an ionic conductor according to any one of claims 1 to 3, characterized in that: The obtained ionic conductor has LiCB9H 10 The high-temperature phase is a single-phase crystal structure.

11. The method for manufacturing an ionic conductor according to any one of claims 1 to 3, characterized in that: The obtained ionic conductor exhibits X-ray diffraction peaks at at least 2θ = 14.9 ± 0.3 deg, 16.4 ± 0.3 deg, and 17.1 ± 0.5 deg in X-ray diffraction measurements at 25 °C. The intensity ratio B / A, calculated from A = (X-ray diffraction intensity at 16.4 ± 0.3 deg) - (X-ray diffraction intensity at 20 deg) and B = (X-ray diffraction intensity at 17.1 ± 0.5 deg) - (X-ray diffraction intensity at 20 deg), is 1.0–20.

12. The method for manufacturing an ionic conductor according to any one of claims 1 to 3, characterized in that: The obtained ionic conductor has an ionic conductivity of 1.0–10 mS / cm at 25 °C. -1 .

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