阅读说明：本技术 包含LiCB9H10的高温相的离子导体及其制造方法、和包含该离子导体的全固体电池用固体电解质 (Comprising LiCB9H10And a method for producing the same, and a solid electrolyte for all-solid-state batteries containing the same ) 是由 野上玄器 野口敬太 金相仑 折茂慎一 于 2019-08-16 设计创作，主要内容包括：根据本发明的一个方式,提供一种包含LiCB-9H-(10)和LiCB-(11)H-(12)的离子导体的制造方法,该方法包括将LiCB-9H-(10)和LiCB-(11)H-(12)以LiCB-9H-(10)/LiCB-(11)H-(12)＝1.1～20的摩尔比混合的工序。根据本发明的另一方式,提供一种包含锂(Li)、碳(C)、硼(B)和氢(H)的离子导体,其在25℃下进行X射线衍射测定时,至少在2θ＝14.9±0.3deg、16.4±0.3deg、17.1±0.5deg具有X射线衍射峰,根据A＝(16.4±0.3deg的X射线衍射强度)－(20deg的X射线衍射强度)、B＝(17.1±0.5deg的X射线衍射强度)－(20deg的X射线衍射强度)算出的强度比(B/A)为1.0～20。(According to one embodiment of the present invention, there is provided a composition comprising LiCB 9 H 10 And LiCB 11 H 12 The method for producing an ion conductor, which comprises subjecting LiCB 9 H 10 And LiCB 11 H 12 With LiCB 9 H 10 /LiCB 11 H 12 Mixing at a molar ratio of 1.1 to 20. According to another aspect of the present invention, there is provided an ion conductor including lithium (Li), carbon (C), boron (B), and hydrogen (H), which has X-ray diffraction peaks at least at 14.9 ± 0.3deg, 16.4 ± 0.3deg, and 17.1 ± 0.5deg, when measured by X-ray diffraction at 25 ℃, and has an intensity ratio (B/a) of 1.0 to 20 calculated from an a ═ X-ray diffraction intensity (16.4 ± 0.3 deg) - (20deg X-ray diffraction intensity), and a B ═ X-ray diffraction intensity (17.1 ± 0.5 deg) - (20deg X-ray diffraction intensity).)

1. A method for manufacturing an ion conductor comprising LiCB₉H₁₀And LiCB₁₁H₁₂The manufacturing method is characterized by comprising:

mixing LiCB₉H₁₀And LiCB₁₁H₁₂With LiCB₉H₁₀/LiCB₁₁H₁₂And (3) mixing the components in a molar ratio of 1.1 to 20.

2. The method for manufacturing an ion conductor according to claim 1, wherein:

the mixing is performed by performing a mechanical milling process.

3. The method for manufacturing an ion conductor according to claim 2, wherein:

the time for performing the mechanical polishing treatment is 1 to 48 hours.

4. The method for manufacturing an ion conductor according to any one of claims 1 to 3, wherein:

the obtained ion conductor has X-ray diffraction peaks at least at 14.9 + -0.3 deg.C, 16.4 + -0.3 deg.C, and 17.1 + -0.5 deg.C when measured by X-ray diffraction at 25 deg.C, and the intensity ratio B/A calculated from A ═ 14.9 + -0.3 deg.C-20 deg.C and B ═ 17.1 + -0.5 deg.C-20 deg.C.

5. An ion conductor comprising lithium (Li), carbon (C), boron (B), and hydrogen (H), characterized in that:

when measured by X-ray diffraction at 25 ℃, the compound has X-ray diffraction peaks at least at 2 theta of 14.9 +/-0.3 deg, 16.4 +/-0.3 deg and 17.1 +/-0.5 deg, and the intensity ratio B/A calculated from A (X-ray diffraction intensity of 16.4 +/-0.3 deg) - (X-ray diffraction intensity of 20 deg) and B (X-ray diffraction intensity of 17.1 +/-0.5 deg) - (X-ray diffraction intensity of 20 deg) is 1.0-20.

6. The ion conductor of claim 5, wherein:

the ion conductor comprises LiCB₉H₁₀。

7. The ion conductor of claim 6, wherein:

the ion conductor further comprises LiCB₁₁H₁₂。

8. The ion conductor of any of claims 5 to 7, wherein:

in Raman spectroscopy, at 749cm^－1(±5cm^－1) And 763cm^－1(±5cm^－1) Each having a peak.

9. The ion conductor of any of claims 5 to 8, wherein:

the ionic conductivity at 25 ℃ is 1.0-10 mScm^－1。

10. A solid electrolyte for an all-solid battery, comprising:

an ion conductor as claimed in any one of claims 5 to 9.

11. An electrode, characterized by:

by contacting the solid electrolyte of claim 10 with lithium metal.

12. An all-solid battery characterized by comprising:

the electrode of claim 11.

Technical Field

The present invention relates to compositions comprising LiCB₉H₁₀The high-temperature phase ion conductor of (1), a method for producing the same, and a solid electrolyte for all-solid-state batteries containing the same.

Background

In recent years, there has been an increasing demand for lithium ion secondary batteries for applications such as mobile information terminals, mobile electronic devices, electric vehicles, hybrid electric vehicles, and stationary power storage systems. However, current lithium ion secondary batteries use flammable organic solvents as the electrolyte solution, and require a strong exterior to prevent leakage of the organic solvents. Further, in portable computers and the like, it is necessary to adopt a structure capable of providing for a risk in case of leakage of the electrolytic solution, and there is a limitation on the structure of the apparatus.

Further, the applications thereof are expanding to mobile bodies such as automobiles and airplanes, and a large capacity is required for a stationary lithium ion secondary battery. Under such circumstances, there is a trend toward higher importance on safety than ever, and efforts have been made to develop all-solid-state lithium-ion secondary batteries that do not use harmful substances such as organic solvents.

For example, as a solid electrolyte in an all-solid lithium ion secondary battery, use of an oxide, a phosphoric acid compound, an organic polymer, a sulfide, a complex hydride, and the like has been studied.

The large category of all-solid batteries is classified into a film type and a bulk type. In the thin film type, although interface bonding can be formed ideally by vapor phase deposition, the electrode layer is as thin as several μm, the electrode area is small, the energy that can be stored per 1 unit is small, and the cost is high. Therefore, it is not suitable as a large-sized power storage device requiring storage of a large amount of energy and a battery for an electric vehicle. On the other hand, the thickness of the bulk-type electrode layer can be set to several tens μm to 100 μm, and an all-solid-state battery having a high energy density can be manufactured.

Among solid electrolytes, sulfide and complex hydride have characteristics of high ionic conductivity and relatively soft and thus easily form a solid-solid interface, and application to a bulk-type all-solid battery is being studied (patent documents 1 and 2).

However, the conventional sulfide solid electrolyte has a property of reacting with water, and sulfide generates hydrogen sulfide, thereby causing a technical problem that the ionic conductivity is lowered after the reaction with water. On the other hand, the complex hydride solid electrolyte tends to have a slightly lower ion conductivity than the sulfide solid electrolyte, and it is desired to improve the ion conductivity.

Patent document 3 describes a so-called carborane-based solid electrolyte, but does not describe ion conductivity.

Documents of the prior art

Patent document

Patent document 1: japanese patent 6246816

Patent document 2: WO 2017-126416

Patent document 3: US2016/0372786A1

Disclosure of Invention

Technical problem to be solved by the invention

An object of the present invention is to provide an ion conductor having excellent various characteristics such as ion conductivity, a method for producing the same, and a solid electrolyte for an all-solid-state battery including the ion conductor.

Technical solution for solving technical problem

The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, have found that LiCB can be used as a material for a semiconductor device₉H₁₀And LiCB₁₁H₁₂The ion conductor obtained by mixing the components at a specific molar ratio can solve the above-mentioned problems. Namely, the present invention is as follows.

< 1 > a method for producing an ion conductor comprising LiCB₉H₁₀And LiCB₁₁H₁₂The manufacturing method comprises the following steps:

mixing LiCB₉H₁₀And LiCB₁₁H₁₂With LiCB₉H₁₀/LiCB₁₁H₁₂And (3) mixing the components in a molar ratio of 1.1 to 20.

< 2 > the method for producing an ion conductor as described in the above < 1 >, wherein the mixing is performed by performing a mechanical polishing treatment.

< 3 > the method for producing an ion conductor as described in < 2 >, wherein the mechanical polishing treatment is performed for 1 to 48 hours.

< 4 > the method for producing an ion conductor, according to any one of the above < 1 > to < 3 >, wherein the obtained ion conductor has an X-ray diffraction peak at least at 14.9 ± 0.3deg, 16.4 ± 0.3deg and 17.1 ± 0.5deg, and an intensity ratio (B/a) calculated from a ═ 14.9 ± 0.3deg (X-ray diffraction intensity of 16.4 ± 0.3 deg) - (X-ray diffraction intensity of 20 deg) and B ═ 17.1 ± 0.5deg (X-ray diffraction intensity of 20 deg) is 1.0 to 20, when measured by X-ray diffraction at 25 ℃.

< 5 > an ion conductor comprising lithium (Li), carbon (C), boron (B) and hydrogen (H), having X-ray diffraction peaks at least at 2 θ ═ 14.9. + -. 0.3deg, 16.4. + -. 0.3deg and 17.1. + -. 0.5deg when measured by X-ray diffraction at 25 ℃, and having an intensity ratio (B/A) of 1.0 to 20 calculated from A ═ 14.9. + -. 0.3deg X-ray diffraction intensity (X-ray diffraction intensity of 16.4. + -. 0.3 deg) to 20deg X-ray diffraction intensity (X-ray diffraction intensity of 17.1. + -. 0.5 deg) and B ═ 17.1. + -. 0.5deg X-ray diffraction intensity (X-ray diffraction intensity of 20 deg).

< 6 > the ion conductor as stated in above < 5 >, wherein the above ion conductor comprises LiCB₉H₁₀。

< 7 > the ion conductor as stated in above < 6 >, wherein the above ion conductor further comprises LiCB₁₁H₁₂。

< 8 > the ion conductor according to any one of the above < 5 > - < 7 > which is 749cm in Raman spectroscopy^－1(±5cm^－1) And 763cm^－1(±5cm^－1) Each having a peak.

< 9 > the ion conductor according to any one of the above < 5 > to < 8 >, wherein the ionic conductivity at 25 ℃ is 1.0 to 10mScm^－1。

< 10 > a solid electrolyte for all-solid batteries, comprising the ion conductor as defined in any one of the above < 5 > to < 9 >.

< 11 > an electrode obtained by bringing the solid electrolyte as described above < 10 > into contact with metallic lithium.

< 12 > an all-solid-state battery having the electrode as described above < 11 >.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, an ion conductor excellent in various characteristics such as ion conductivity, a method for producing the same, and a solid electrolyte for an all-solid-state battery including the ion conductor can be provided.

Drawings

FIG. 1A shows X-ray diffraction peaks of powders of ion conductors obtained in examples 1 to 4 and comparative example 1.

Fig. 1B is an enlarged view of a part of the X-ray diffraction spectrum of fig. 1A.

FIG. 2A shows Raman spectra of the ion conductors obtained in examples 1 to 4 and comparative example 1.

Fig. 2B is a diagram in which a part of the raman spectrum of fig. 1A is enlarged.

FIG. 3 shows the results of measuring the ion conductivity of the ion conductors obtained in examples 1 to 4 and comparative example 1.

Fig. 4A shows the results of measuring the voltage applied between the electrodes of the evaluation unit in example 5.

Fig. 4B is an enlarged view of a part of fig. 4A.

Fig. 5A shows the results of the charge and discharge test in example 6.

Fig. 5B shows the results of the charge and discharge test in example 6.

Detailed Description

Hereinafter, embodiments of the present invention will be described. The materials, structures, and the like described below are not intended to limit the present invention, and various modifications can be made within the scope of the present invention.

1. Ion conductor

According to an embodiment of the present invention, there is provided an ion conductor including lithium (Li), carbon (C), boron (B), and hydrogen (H). The above embodiment preferably contains LiCB as a crystal₉H₁₀More preferably, the high temperature phase (high ion conducting phase) of (2), more preferably comprises LiCB₉H₁₀And LiCB₁₁H₁₂。

The ion conductor of the invention is preferably based on LiCB in Raman spectroscopy₉H₁₀749cm^－1(±5cm^－1) And based on LiCB₁₁H₁₂763cm^－1(±5cm^－1) Each having a peak. Peaks may be present in other regions, but peaks representing each feature are as described above.

The ion conductor of the present invention preferably contains LiCB as a crystal₉H₁₀The high temperature phase of (2). LiCB₉H₁₀Has a high temperature phase and a low temperature phase depending on the crystalline state, and has a high ionic conductivity at a high temperature (for example, about 75 to 150 ℃) and a low temperature at a temperature around room temperature (for example, about 20 to 65 ℃), and the ionic conductivity is lowered。

The ion conductor of the present invention has a structure based on LiCB at least in terms of 2 theta 14.9 + -0.3 deg, 16.4 + -0.3 deg, 17.1 + -0.5 deg as measured by X-ray diffraction at 25 deg.C₉H₁₀X-ray diffraction peak of the high temperature phase (2). The intensity ratio (B/a) calculated from a ═ X-ray diffraction intensity (16.4 ± 0.3 deg) - (20deg X-ray diffraction intensity) and B ═ X-ray diffraction intensity (17.1 ± 0.5 deg) - (20deg X-ray diffraction intensity) is preferably in the range of 1.0 to 20, more 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, the intensity ratio is determined by adding LiCB₉H₁₀High temperature phase solid solution LiCB of₁₁H₁₂Therefore, the phase transition temperature is lowered, and the state of high ionic conductivity can be maintained even at around room temperature. In LiCB₉H₁₀/LiCB₁₁H₁₂When the molar ratio is 1.1 or more, the solid solution is established. LiCB is preferred₉H₁₀/LiCB₁₁H₁₂1.1 to 20, more preferably LiCB₉H₁₀/LiCB₁₁H₁₂When the ratio is 1.25 to 10, LiCB is particularly preferable₉H₁₀/LiCB₁₁H₁₂1.5 to 9, and in this range, the ionic conductivity shows a high value.

In addition, the ion conductor of the present invention can obtain a desired effect even if it includes an X-ray diffraction peak other than the above.

The ion conductor of the present invention may contain components other than lithium (Li), carbon (C), boron (B), and hydrogen (H). Examples of the other components include oxygen (O), nitrogen (N), sulfur (S), fluorine (F), Chlorine (CI), bromine (Br), iodine (I), silicon (Si), germanium (Ge), phosphorus (P), alkali metals, and alkaline earth metals.

The ion conductor is flexible and can be formed into an electrode layer and a solid electrolyte layer by cold pressing. The electrode layer and the solid electrolyte layer thus formed are superior in strength to those containing a large amount of sulfide solid electrolyte or oxide solid electrolyte. Therefore, by using the ion conductor of the present invention, an electrode layer and a solid electrolyte layer which have good formability and are less likely to be broken (are less likely to be cracked) can be produced. Further, since the ion conductor of the present invention has a low density, it is possible to manufacture a relatively light electrode layer and a relatively light solid electrolyte layer. This is preferable because the weight of the entire battery can be reduced. In addition, when the ion conductor of the present invention is used for the solid electrolyte layer, the interface resistance with the electrode layer can be reduced.

Furthermore, the ion conductor does not decompose even when contacted with moisture or oxygen, and does not generate dangerous toxic gas.

The ionic conductor preferably has an ionic conductivity of 1.0 to 10mScm at 25 DEG C^－1More preferably 2.0 to 10mScm^－1。

2. Method for manufacturing ion conductor

According to another embodiment of the present invention, there is provided a method of manufacturing an ion conductor including LiCB₉H₁₀And LiCB₁₁H₁₂The preparation method comprises the step of mixing LiCB₉H₁₀And LiCB₁₁H₁₂With LiCB₉H₁₀/LiCB₁₁H₁₂And (3) mixing the components in a molar ratio of 1.1 to 20.

LiCB as a raw material₉H₁₀And LiCB₁₁H₁₂Generally commercially available substances can be used. The purity is preferably 95% or more, and more preferably 98% or more. By using a compound having a purity within the above range, a desired crystal can be easily obtained.

LiCB is required to be mixed₉H₁₀With LiCB₁₁H₁₂The mixing ratio of (A) is LiCB₉H₁₀/LiCB₁₁H₁₂1.1 or more. LiCB is preferred₉H₁₀/LiCB₁₁H₁₂1.1 to 20, more preferably LiCB₉H₁₀/LiCB₁₁H₁₂When the ratio is 1.25 to 10, LiCB is particularly preferable₉H₁₀/LiCB₁₁H₁₂1.5 to 9. As described above, in this range, the ion conductivity exhibits a particularly high value.

LiCB₉H₁₀And LiCB₁₁H₁₂Is preferably mixed in an inert gasThe reaction is carried out under an atmosphere. Examples of the inert gas include helium, nitrogen, and argon is preferable. The concentrations of water and oxygen in the inert gas are preferably controlled to be low, and more preferably less than 1 ppm.

The mixing method is not particularly limited, and stirring and mixing in a solvent can be employed. Mechanical mixing can also be employed, and examples thereof include a method using a kneader, a ball mill, a planetary ball mill, a bead mill, a rotary and orbital mixer, a high-speed stirring type mixing device, a drum mixer, and the like. Among these, a planetary ball mill having excellent pulverizing power and mixing power is more preferable, and particularly, a mechanical grinding treatment using a planetary ball mill is preferably performed to mix them. The mechanical mixing is preferably carried out dry, but may also be carried out in a solvent. The solvent is not particularly limited regardless of the method, and examples thereof include nitrile solvents including acetonitrile, ether solvents such as tetrahydrofuran and diethyl ether, alcohol solvents such as N, N-dimethylformamide, N-dimethylacetamide and methanol and ethanol.

The mixing time varies depending on the mixing method, and when the mixture is stirred and mixed in a solvent, the mixing time is, for example, 1 to 48 hours, preferably 5 to 24 hours. In addition, in the case of using a solvent, the mixing time can be shortened. The mixing time in the mechanical mixing is, for example, 1 to 24 hours, preferably 5 to 20 hours in the case of using a planetary ball mill.

The reaction pressure is usually in the range of 0.1Pa to 2MPa in terms of absolute pressure. Preferably from 101kPa to 1 MPa.

The ion conductor obtained by the above-described production method of the present invention is preferably based on LiCB in raman spectroscopy measurement₉H₁₀749cm^－1(±5cm^－1) And based on LiCB₁₁H₁₂763cm^－1(±5cm^－1) Each having a peak. In addition, when the X-ray diffraction measurement is carried out at 25 ℃, at least 2 theta is 14.9 +/-0.3 deg, 16.4 +/-0.3 deg and 17.1 +/-0.5 deg based on LiCB₉H₁₀The high temperature phase of (2) is determined by (16.4. + -. 0.3deg X-ray diffraction intensity) - (20 deg) according to A ═ X-ray diffraction intensityThe X-ray diffraction intensity of (1), B ═ an intensity ratio (B/a) calculated from (17.1 ± 0.5deg X-ray diffraction intensity) - (20deg X-ray diffraction intensity) 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.

3. All-solid-state battery

The ion conductor of the present invention can be used as a solid electrolyte for an all-solid battery. Therefore, according to an embodiment of the present invention, there is provided a solid electrolyte for an all-solid battery including the above-described ion conductor. In another embodiment of the present invention, there is provided an all-solid-state battery using the solid electrolyte for an all-solid-state battery.

In the present specification, an all-solid battery refers to an all-solid battery in which lithium ions are responsible for electrical conduction, and particularly to 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 invention may be contained as a solid electrolyte in any one or more of the positive electrode layer, the negative electrode layer, and the solid electrolyte layer. In the case of use in an electrode layer, it is more preferable to use in a positive electrode layer than in a negative electrode layer. This is because the positive electrode layer is less likely to cause side reactions. When the ion conductor of the present invention is included 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 positive electrode layer, if a bulk type in which an active material and a solid electrolyte are mixed with each other is used, the capacity per unit becomes large, and thus it is preferable.

The all-solid-state battery is produced by molding and laminating the above-described layers, but the molding method and the laminating method of the layers are not particularly limited. For example, the following methods are available: a method in which a solid electrolyte and/or an electrode active material are dispersed in a solvent to prepare a slurry-like object, the slurry-like object is coated by blade coating, spin coating, or the like, and the coated object is rolled to form a film; a vapor phase method in which film formation and lamination are performed by a vacuum evaporation method, an ion plating method, a sputtering method, a laser ablation method, or the like; a pressing method in which a powder is formed by hot pressing or cold pressing without applying a temperature, and is laminated. The ion conductor of the present invention is relatively flexible, and is particularly preferably molded and laminated by pressing to produce a battery. Alternatively, an electrode layer containing an active material, a conductive auxiliary agent, and a binder may be formed in advance, and a solution obtained by dissolving a solid electrolyte in a solvent or a slurry obtained by dispersing a solid electrolyte in a solvent may be poured into the electrode layer, and then the solvent may be removed to incorporate the solid electrolyte into the electrode layer.

The atmosphere for producing the all-solid-state battery is preferably performed in an inert gas or dry chamber in which the moisture is controlled. The water content is controlled in the range of-10 ℃ to-100 ℃, more preferably in the range of-20 ℃ to-80 ℃, and particularly preferably in the range of-30 ℃ to-75 ℃. This is because the hydrolysis rate of the ion conductor of the present invention is extremely slow, but the ion conductivity is prevented from being lowered by the formation of hydrate.

Examples

The present invention will be described in detail below with reference to examples, but the present invention is not limited thereto.

< preparation of ion conductor >

(example 1)

In a glove box under argon atmosphere, LiCB was charged₉H₁₀(Katchem Co., Ltd.) and LiCB₁₁H₁₂(Katchem Co., Ltd.) to obtain LiCB₉H₁₀﹕LiCB₁₁H₁₂100mg were measured at a molar ratio of 9: 1 and premixed using an agate mortar. Then, the premixed raw materials were put into a 45mL SUJ-2 canister, and further SUJ-2 balls (20) the cans were completely sealed. The pot was mounted on a planetary ball mill (P7 manufactured by Fritsch), and mechanical milling was performed at 400rpm for 20 hours to obtain an ion conductor. As a result of X-ray diffraction, the obtained ion conductor contained LiCB₉H₁₀The high temperature phase of (2).

(example 2)

Mixing LiCB₉H₁₀And LiCB₁₁H₁₂The mixing molar ratio of (A) was changed to LiCB₉H₁₀﹕LiCB₁₁H₁₂An ion conductor was produced in the same manner as in example 1, except that the ratio was 8: 2.

(example 3)

Mixing LiCB₉H₁₀And LiCB₁₁H₁₂The mixing molar ratio of (A) was changed to LiCB₉H₁₀﹕LiCB₁₁H₁₂Ion conductors were produced in the same manner as in example 1, except that the ion conductors were 7: 3.

(example 4)

Mixing LiCB₉H₁₀And LiCB₁₁H₁₂The mixing molar ratio of (A) was changed to LiCB₉H₁₀﹕LiCB₁₁H₁₂Ion conductors were produced in the same manner as in example 1, except that the ion conductors were 6: 4.

Comparative example 1

Mixing LiCB₉H₁₀And LiCB₁₁H₁₂The mixing molar ratio of (A) was changed to LiCB₉H₁₀﹕LiCB₁₁H₁₂Ion conductors were produced in the same manner as in example 1, except that the ratio was 5: 5. According to the results of X-ray diffraction, the obtained ion conductor was LiCB₉H₁₀And LiCB₁₁H₁₂Mixing phases of (1).

< X-ray diffraction measurement >

The ion conductor powders obtained in examples 1 to 4 and comparative example 1 were subjected to X-ray diffraction measurement (X 'pert Pro, manufactured by PANALYTIC Co., Ltd., X' Pert Pro, X 'Per T O, X' K, Y.K.) using a Lindman glass capillary (outer diameter 0.5mm, thickness 0.01mm) under an argon atmosphere at room temperature (25 ℃ C, The obtained X-ray diffraction peaks are shown in fig. 1A and 1B. FIG. 1A also shows LiCB as a raw material for comparison₉H₁₀And LiCB₁₁H₁₂X-ray diffraction peak of (2).

In examples 1 to 4, X-ray diffraction peaks were observed at least at 14.9 ± 0.3deg, 16.4 ± 0.3deg, and 17.1 ± 0.5 deg. And will be LiCB₉H₁₀The intensities at the peak positions of 16.44deg and 17.07deg of the high-temperature phase of (2) are shown as A and B, respectively, and the intensity ratios (B/A) are shown in Table 1. The intensities were calculated from a ═ a (X-ray diffraction intensity of 16.44 deg) - (X-ray diffraction intensity of 20 deg) and B ═ B (X-ray diffraction intensity of 17.07 deg) - (X-ray diffraction intensity of 20 deg), with the value of 2 θ ═ 20deg as a baseline.

Examples 1 to 4 and LiCB₉H₁₀The peak positions of the high-temperature phases are identical, and hence it is known that the phases become solid solutions, but comparative example 1 is LiCB₉H₁₀Low temperature phase and LiCB₁₁H₁₂The mixed phase (2) is not in the solid solution region.

[ Table 1]

TABLE 1 Strength ratio of examples and comparative examples

	Example 1	Example 2	Example 3	Example 4	Comparative example 1
						LiCB9H10﹕LiCB11H12	9﹕1	8﹕2	7﹕3	6﹕4	5﹕5
Intensity ratio (B/A)	8.6	4.7	2.6	1.6	0.93

< Raman Spectroscopy >

(1) Sample preparation

Using a quartz glass having (A) in the upper partThickness 1mm) was prepared as a closed container for an optical window. The liquid was stored in a glove box under an argon atmosphere in a state where the sample was in contact with quartz glass, and then the container was closed and taken out of the glove box to perform raman spectroscopy.

(2) Measurement conditions

The measurement was carried out using a laser Raman spectrometer NRS-5100 (manufactured by Nippon spectral Co., Ltd.) at an excitation wavelength of 532.15nm and an exposure time of 5 seconds. The obtained raman spectrum is shown in fig. 2.

LiCB₉H₁₀At 749cm^－1Having a peak, LiCB₁₁H₁₂At 763cm^－1With a peak. In addition, the raman shift value is derived from bonding and is hardly affected by the crystal state. 763cm in examples 1 to 2^－1Has a peak of 749cm^－1Shoulder of (4) in examples 3 to 4 and comparative example 1, 749cm^－1Peak of (2) is 763cm^－1Although LiCB was found to be present₉H₁₀And LiCB₁₁H₁₂。

< determination of ion conductivity >

In a glove box under argon atmosphere, the ion conductors obtained in examples 1 to 4 and comparative example 1 and LiCB as a raw material were placed₉H₁₀And LiCB₁₁H₁₂Uniaxially molded (240MPa) to obtain a sheet having a thickness of about 1mm,A disc of (2). The temperature was raised and lowered at intervals of 10 ℃ in a temperature range from room temperature to 150 ℃ or 80 ℃, and the ionic conductivity was calculated by measuring the ac impedance by a two-terminal method using a lithium electrode (HIOKI 3532-80, chemical impedance meter). The measurement frequency range is 4 Hz-1 MHz, and the amplitude is 100 mV.

Fig. 3 shows the measurement results of the ion conductivity of each sample. The ionic conductivity at room temperature (25 ℃ C.) is shown in Table 2. In addition, in examples 1 to 4 and comparative example 1, LiCB as a raw material was not observed₉H₁₀And LiCB₁₁H₁₂The phenomenon of sharp drop of ion conductivity at low temperature is seen. However, it is understood that the difference between the ion conductivity of comparative example 1 and examples 1 to 4 is large, and even in example 4 having the lowest ion conductivity among examples 1 to 4, the ion conductivity at room temperature is improved by 2 times as compared with comparative example 1.

[ Table 2]

Ionic conductivity at 225 ℃ in Table

	Example 1	Example 2	Example 3	Example 4	Comparative example 1
						LiCB9H10﹕LiCB11H12	9﹕1	8﹕2	7﹕3	6﹕4	5﹕5
Ion conductivity/mScm－1	2.3	2.2	1.4	1.0	0.49

(example 5)

< dissolution/precipitation test with lithium symmetrical cell >

The ion conductor powder obtained in example 3 was put into a powder tablet forming machine having a diameter of 8mm, and was press-formed into a disk shape under a pressure of 143MPa, to obtain a disk-shaped pellet in which a solid electrolyte layer (300 μm) was laminated. The pellets were stuck on both sides thereof in a thickness of 200 μm,The lithium metal foil (manufactured by Wako metals Co., Ltd.) was put into a constraint test cell (manufactured by Baoquan) for an all-solid battery made of SUS304 and sealed to prepare an evaluation cell. All the above operations were carried out in a glove box under an argon atmosphere. The evaluation unit thus prepared was measured for temperature of 25 ℃ and current density using a potentiostat/galvanostat (VMP 3, Bio-Logic)0.2mA/cm^－2The process of reversing the polarity and flowing a current for 0.5 hours each was set to 1 cycle (1 cycle for 1 hour), and the voltage applied between the electrodes of the evaluation unit was measured. The results are shown in FIG. 4. The overvoltage is as small as less than 0.01V and is stable, and an abnormal voltage is not shown. Even after 100 cycles, the increase in overvoltage was only slight, indicating that the dissolution/precipitation of Li was repeated well.

(example 6)

< Charge and discharge test >

(preparation of Positive electrode active Material)

Sulfur (S) (purity 99.98% manufactured by Sigma-Aldrich), ketjen black (EC 600JD manufactured by Lion corporation) and Maxsorb (registered trademark) (MSC 30 manufactured by kansy thermal chemistry) were placed in a 45mL SUJ-2 canister so as to obtain a weight ratio of S: ketjen black: Maxsorb (registered trademark): 50: 25. Further put SUJ-2 into the pellet (20) the cans were completely sealed. The pot was mounted on a planetary ball mill (P7, manufactured by Fritsch), and mechanically ground at 400rpm for 20 hours to obtain an S-carbon composite positive electrode active material.

(preparation of Positive electrode layer powder)

The positive electrode layer powder was prepared by weighing and mixing the S-carbon composite positive electrode active material prepared as described above with the ion conductor obtained in example 3 at a weight ratio of 1: 1 in a glove box.

(preparation of all-solid-State Battery)

The ion conductor powder obtained in example 3 was put into a powder tablet forming machine having a diameter of 10mm, and was press-formed into a disk shape under a pressure of 143MPa (formation of a solid electrolyte layer). The positive electrode layer powder prepared as described above was put into a tablet molding machine without taking out the molded product, and was integrally molded under a pressure of 285 MPa. Thus, a disk-shaped pellet in which a positive electrode layer (75 μm) and a solid electrolyte layer (300 μm) were laminated was obtained. The pellets were bonded to the opposite side of the positive electrode layer with a thickness of 200 μm,The lithium metal foil (manufactured by Wako metals Co., Ltd.) was used as a lithium negative electrode layer, and the lithium negative electrode layer was put into a constraint test cell (manufactured by Baoquan) for an all-solid secondary battery made of SUS304 and sealed to obtain an all-solid secondary battery.

(Charge and discharge test)

The all-solid-state secondary battery obtained as described above was subjected to a charge/discharge test from the start of discharge using a potentiostat/galvanostat (VMP 3, Bio-Logic) at a measurement temperature of 25 ℃, a cut-off voltage of 1.0 to 2.5V, and a constant current of 0.1C. The discharge capacity obtained in the battery subjected to the test was expressed as a value per 1g of the sulfur-based electrode active material. Then, the coulomb efficiency is calculated from the charge capacity/discharge capacity. The results are shown in FIG. 5.

Although a large irreversible capacity was observed at the time of initial discharge, high coulombic efficiency of 98% or more was shown after the 2 nd cycle. The discharge capacity at the first cycle was 1900mAh/g as the cycle characteristic, while 1300mAh/g at the 2 nd cycle showed a large drop, but was stable after the 3 rd cycle and was 1100mAh/g at the 20 th cycle, and a large apparent capacity could be obtained.