CN100583543C - Lithium ion conductive solid electrolyte, method for producing same, solid electrolyte for lithium secondary battery using same, and all-solid-state lithium battery using same - Google Patents

Abstract

The present invention provides a lithium ion conductive solid electrolyte, which also shows high lithium ion conductivity at room temperature, is difficult to be oxidized, and has few toxicity problems, and contains lithium (Li), boron ( B), sulfur (S) and oxygen (O) elements, the ratio of sulfur and oxygen elements (O/S) is 0.01 to 1.43.

Description

Lithium-ion conductive solid electrolyte, method for producing same, solid electrolyte for lithium secondary battery using the same, and all-solid lithium battery using the solid electrolyte for secondary battery

technical field

The present invention relates to: a lithium-ion conductive solid electrolyte containing lithium, boron, sulfur and oxygen as constituents and having a specific ratio of sulfur to oxygen; containing lithium, boron, sulfur and oxygen as constituents and having a specific X-ray The lithium ion conductive solid electrolyte of the diffraction peak; lithium sulfide (Li ₂ S): diboron trisulfide (B ₂ S ₃ ): the molar % ratio of the compound represented by Li _a MO _b has the following formula X(100-Y): (1-X)(100-Y): Lithium-ion conductive solid electrolyte of the composition represented by Y; sulfide glass of the composition [wherein, M represents a composition selected from phosphorus, silicon, aluminum, boron, sulfur, germanium, gallium , elements in indium, a and b independently represent a number from 1 to 10, X represents a number from 0.5 to 0.9, and Y represents 0.5 to 30 mol%. ]Method for producing solid electrolyte heat-treated at 100 to 350°C; lithium ion conductive solid electrolyte obtained by the production method; solid electrolyte for lithium secondary battery using the solid electrolyte and solid electrolyte for secondary battery using the solid electrolyte An all-solid lithium battery.

Background technique

In recent years, the demand for high-performance lithium secondary batteries used in portable information terminals, portable electronic devices, household small power storage devices, two-wheeled motorcycles powered by electric motors, electric vehicles, and hybrid electric vehicles is increasing. Increase.

Here, the term "secondary battery" refers to a battery that can be charged and discharged.

In addition, with the expansion of usable applications, further improvements in safety and performance of secondary batteries are required.

Inorganic solid electrolytes are nonflammable in nature and are safer materials than commonly used organic electrolytes.

However, due to poor electrochemical performance compared with organic-based electrolytes, further improvement in the performance of inorganic solid electrolytes is required.

Conventionally, electrolytes exhibiting high lithium ion conductivity at room temperature were basically limited to organic electrolytes.

However, conventional organic electrolytes are flammable because they contain organic solvents.

Therefore, when an ion conductive material containing an organic solvent is used as an electrolyte of a battery, there is a possibility of liquid leakage or a risk of ignition.

In addition, since this organic electrolyte is a liquid, it not only conducts lithium ions but also conducts counter ions, so the mobility of lithium ions is 1 or less.

In response to such problems, various sulfide-based solid electrolytes have been studied in the past.

For example, in the 1980s, sulfide glasses with an ion conductivity of 10 ^-3 S/cm, such as LiI-Li ₂ SP ₂ S ₅ , LiI-Li ₂ SB ₂ S ₃ , LiI-Li ₂ S-SiS ₂ , etc.

However, in order to improve ionic conductivity, these solid electrolytes are doped with lithium iodide, so they are susceptible to electrochemical oxidation, and it is difficult to form an all-solid lithium battery that operates above 3V.

In addition, phosphorus pentasulfide (P ₂ S ₅ ) used as a raw material of the solid electrolyte has a problem of toxicity, which causes industrial difficulties.

Contents of the invention

Under such circumstances, the present invention aims to provide a lithium ion conductive solid electrolyte, which also exhibits high lithium ion conductivity at room temperature, is difficult to be oxidized, and has few toxicity problems; the solid electrolyte A manufacturing method; a solid electrolyte obtained by the manufacturing method; a solid electrolyte for a lithium secondary battery using the solid electrolyte; and an all-solid lithium battery using the solid electrolyte for the secondary battery.

The inventors of the present invention have repeatedly conducted intensive studies in order to achieve the object, and as a result, have found that, after melting and reacting a raw material mixture composed of lithium sulfide, diboron trisulfide, and a compound represented by the general formula Li _a MO _b , by rapidly cooling, A lithium ion conductive solid electrolyte with high ion conductivity can be obtained, thereby completing the present invention.

That is, the present invention provides:

1. A lithium ion conductive solid electrolyte is characterized in that, as constituents, containing lithium (Li), boron (B), sulfur (S) and oxygen (O) elements, the ratio of sulfur to oxygen elements (O/ S) is 0.01 to 1.43.

2. A lithium ion conductive solid electrolyte, characterized in that lithium sulfide (Li ₂ S): diboron trisulfide (B ₂ S ₃ ): the mole percent ratio of the compound represented by Li _a MO _b has a ratio of X( 100-Y):(1-X)(100-Y):Y represents the composition.

[Wherein, M represents an element selected from phosphorus (P), silicon (Si), aluminum (Al), boron (B), sulfur (S), germanium (Ge), gallium (Ga), indium (In), a and b independently represent a number of 1 to 10, X represents a number of 0.5 to 0.9, and Y represents 0.5 to 30 mol%. ]

3. A lithium ion conductive solid electrolyte, characterized in that, as constituents, containing lithium (Li), boron (B), sulfur (S) and oxygen (O) elements, in X-ray diffraction (CuKα:λ= 0.15418nm), there are diffraction peaks at 2θ=19.540±0.3deg, 28.640±0.3deg and 29.940±0.3deg.

4. A method for producing a lithium ion conductive solid electrolyte, characterized in that the molar % ratio of lithium sulfide (Li ₂ S): diboron trisulfide (B ₂ S ₃ ): the compound represented by Li _a MO _b The sulfide-based glass having a composition represented by X(100-Y):(1-X)(100-Y):Y is heat-treated at 100 to 350°C.

[Wherein, M represents an element selected from phosphorus (P), silicon (Si), aluminum (Al), boron (B), sulfur (S), germanium (Ge), gallium (Ga), indium (In), a and b independently represent a number of 1 to 10, X represents a number of 0.5 to 0.9, and Y represents 0.5 to 30 mol%. ]

5. The method for producing a lithium ion conductive solid electrolyte according to 4 above, wherein the compound represented by the general formula Li _a MO _b is selected from lithium silicate, lithium borate, and lithium phosphate.

6. The method for producing a lithium ion conductive solid electrolyte according to 4 or 5 above, wherein instead of diboron trisulfide, a mixture of boron and elemental sulfur is used in an equivalent molar ratio.

7. A lithium ion conductive solid electrolyte obtained by the production method described in any one of 4 to 6 above.

8. A solid electrolyte for a lithium secondary battery using the lithium ion conductive solid electrolyte described in any one of 1 to 3 or 7 above.

9. An all-solid lithium battery using the solid electrolyte for lithium secondary batteries described in 8 above.

Since the lithium ion conductive solid electrolyte of the present invention has a decomposition voltage of at least 10 V or more, it is an inorganic solid, so it is non-flammable, and exhibits 10 ^-3 at room temperature while maintaining the characteristic of lithium ion mobility of 1. Very high lithium ion conductivity around S/cm.

Therefore, it is very suitable as a solid electrolyte material for lithium batteries.

In addition, the all-solid lithium battery using the lithium ion conductive solid electrolyte of the present invention not only has high energy density, is excellent in safety and charge-discharge cycle performance, but also has no high toxicity in the raw materials used.

Description of drawings

FIG. 1 is a graph showing X-ray diffraction patterns of powder samples of molten reactants (before heat treatment) and heat-treated products obtained in Example 1. FIG.

FIG. 2 is a graph showing a cyclic voltammetry curve of a heat-treated product in Example 6. FIG.

FIG. 3 is a graph showing the charge-discharge characteristics of the battery obtained in Example 7. FIG.

Detailed ways

The lithium ion conductive solid electrolyte of the present invention contains lithium, boron, sulfur and oxygen as constituents, and the ratio (O/S) of sulfur to oxygen is 0.01-1.43, preferably 0.03-1.2, more preferably 0.05-1.0.

The lithium ion conductive solid electrolyte includes: sulfide-based glass obtained by rapidly cooling molten reactants described later; sulfide-based crystallized glass obtained by heat-treating the glass; and sulfide-based glass and sulfide-based crystallized glass. Mixture of any proportion of tempered glass.

In addition, the lithium ion conductive solid electrolyte of the present invention is a lithium ion conductive solid electrolyte characterized by lithium sulfide (Li ₂ S): diboron trisulfide (B ₂ S ₃ ): represented by Li _a MO _b The molar % ratio of the compound has a composition represented by X(100-Y):(1-X)(100-Y):Y.

[Wherein, M represents an element selected from phosphorus (P), silicon (Si), aluminum (Al), boron (B), sulfur (S), germanium (Ge), gallium (Ga), indium (In), a and b independently represent a number of 1 to 10, X represents a number of 0.5 to 0.9, and Y represents 0.5 to 30 mol%. ]

The lithium ion conductive solid electrolyte includes: sulfide-based glass obtained by rapidly cooling molten reactants described later; sulfide-based crystallized glass obtained by heat-treating the glass; and sulfide-based glass and sulfide-based crystallized glass. Mixture of any proportion of tempered glass.

In addition, the lithium-ion conductive solid electrolyte of the present invention contains lithium, boron, sulfur, and oxygen elements as constituents, and in X-ray diffraction (CuKα: λ=0.15418nm), at 2θ=19.540±0.3deg, 28.640±0.3 There are diffraction peaks at deg and 29.940±0.3deg.

The lithium ion conductive solid electrolyte includes sulfide-based crystallized glass obtained by heat-treating sulfide-based glass described later.

Furthermore, in the lithium ion conductive solid electrolyte of the present invention, elements selected from silicon, phosphorus, aluminum, germanium, gallium, and indium may be added as other constituents.

The lithium ion conductive solid electrolyte of the present invention can be obtained by making lithium sulfide: diboron trisulfide or a mixture of boron and sulfur elements in a molar ratio equivalent to diboron trisulfide: the mole % ratio of the compound represented by Li _a MO _b A raw material mixture composed of X(100-Y):(1-X)(100-Y):Y is melted and reacted, and then quenched to produce it.

M, a, b, X and Y are the same as described above.

In addition, the lithium ion conductive solid electrolyte of the present invention can be obtained by making lithium sulfide: diboron trisulfide or a mixture of boron and sulfur elements in a molar ratio equivalent to diboron trisulfide: the mole of the compound represented by Li _a MO _b The % ratio is X(100-Y):(1-X)(100-Y):Y, the raw material mixture is melted and reacted, then rapidly cooled, and then heat-treated at 100-350° C. to manufacture.

The lithium sulfide used in the present invention is not particularly limited, but the higher the purity, the better.

In addition, diboron trisulfide, boron, and sulfur are not particularly limited, but the higher the purity, the better.

In addition, a compound represented by the general formula Li _a MO _b [wherein, M represents an element selected from phosphorus, silicon, aluminum, boron, sulfur, germanium, gallium, and indium, and a and b independently represent numbers from 1 to 10] It is not particularly limited, but the higher the purity, the more desirable it is.

Lithium silicate (Li ₄ SiO ₄ ), lithium borate (LiBO ₂ ), and lithium phosphate (Li ₃ PO ₄ ) are ideally exemplified as the compound represented by the general formula Li _a MO _b .

The above-mentioned M is a compound of an element selected from phosphorus, aluminum, boron, germanium, gallium, and indium other than silicon, and it is not particularly limited as long as it forms a compound having the same crystal structure as lithium silicate, lithium borate, and lithium phosphate. .

Examples of these compounds include LiAlO ₂ , Li ₃ BO ₃ , Li ₂ SO ₄ and the like.

As diboron trisulfide, boron, sulfur, and compounds represented by the general formula Li _a MO _b used in the present invention, commercially available products can be used as long as they are of high purity.

In the present invention, the content of the compound represented by the general formula Li _a MO _b in the raw material mixture is 0.5-30 mol%, preferably 1-20 mol%, more preferably 1-15 mol%.

In addition, the content of lithium sulfide is preferably 50 to 99 mol%, more preferably 55 to 85 mol%, and even more preferably 60 to 80 mol%, and the rest is diboron trisulfide or boron and sulfur in a molar ratio equivalent to diboron trisulfide. A mixture of elements.

The melting reaction temperature of the mixture is usually 400-1000°C, preferably 600-1000°C, more preferably 700-1000°C, and the melting reaction time is usually 0.1-12 hours, preferably 0.5-10 hours.

The quenching temperature of the molten reactant is usually below 10°C, preferably below 0°C, and the cooling rate is about 0.01-10000K/sec, preferably 1-10000K/sec.

The molten reactant (sulfide-based glass) thus obtained is glassy (completely amorphous), and generally has an ion conductivity of 0.5 to 10×10 ^-4 (S/cm).

The lithium ion conductive solid electrolyte of the present invention can also be produced by heat-treating the molten reactant (sulfide glass).

The heat treatment is 100-350°C, preferably 150-340°C, more preferably 180-330°C, and the heat treatment time is usually 0.01-240 hours, preferably 0.1-24 hours, although it depends on the heat treatment temperature.

By this heat treatment, a partially or completely crystallized solid electrolyte can be obtained.

The solid electrolyte thus obtained generally exhibits an ion conductivity of 3.0×10 ^-4 to 3.0×10 ^-3 (S/cm).

The method for producing lithium sulfide used in the present invention is not particularly limited as long as it can reduce impurities.

For example, it can also be obtained by refining lithium sulfide produced by the following method.

Among the following production methods, the method a or b is particularly preferable.

a. A method in which lithium hydroxide and hydrogen sulfide are reacted at 0 to 150°C in an aprotic organic solvent to generate lithium hydrosulfide, and then the reaction solution is dehydrogenated at 150 to 200°C (JP-330312 Bulletin).

b. A method of directly producing lithium sulfide by reacting lithium hydroxide and hydrogen sulfide in an aprotic organic solvent at 150 to 200° C. (JP-A-7-330312).

c. A method of reacting lithium hydroxide with a gaseous sulfur source at a temperature of 130 to 445°C (JP-A-9-283156).

There are no particular limitations on the method of refining the lithium sulfide obtained as described above.

As a preferable purification method, Japanese Patent Application No. 2003-363403 etc. are mentioned, for example.

Specifically, the lithium sulfide obtained as described above is washed at a temperature of 100° C. or higher using an organic solvent.

The reason why the organic solvent is used at a temperature above 100°C is because N-methylaminobutyric acid, an impurity generated when the organic solvent used in the production of lithium sulfide is N-methyl-2-pyrrolidone (NMP) The temperature at which lithium (LMAB) can be dissolved in an organic solvent is 100°C, so LMAB is dissolved in an organic solvent for washing to remove it from lithium sulfide.

The organic solvent used for washing is preferably an aprotic polar solvent, and more preferably the same aprotic organic solvent used in the production of lithium sulfide is the same as the aprotic polar organic solvent used for washing.

As an aprotic polar organic solvent that can be ideally used in washing, for example, aprotic polar organic compounds such as amide compounds, lactam compounds, urea compounds, organosulfur compounds, and cyclic organophosphorus compounds, It can be ideally used as a single solvent or a mixed solvent.

Among these aprotic polar organic solvents, examples of the amide compound include N,N-dimethylformamide, N,N-diethylformamide, N,N-dimethylacetamide , N, N-dipropylacetamide, N, N-dimethylbenzamide, etc.

In addition, examples of the lactam compound include caprolactam, N-methylcaprolactam, N-ethylcaprolactam, N-isopropylcaprolactam, N-isobutylcaprolactam, N-n-propylcaprolactam, N- N-alkylcaprolactams such as n-butylcaprolactam and N-cyclohexylcaprolactam; N-methyl-2-pyrrolidone (NMP), N-ethyl-2-pyrrolidone, N-isopropyl-2-pyrrolidone, N -Isobutyl-2-pyrrolidone, N-n-propyl-2-pyrrolidone, N-n-butyl-2-pyrrolidone, N-cyclohexyl-2-pyrrolidone, N-methyl-3-methyl-2- Pyrrolidone, N-ethyl-3-methyl-2-pyrrolidone, N-methyl-3,4,5-trimethyl-2-pyrrolidone, N-methyl-2-piperidone, N-ethyl -2-piperidone, N-isopropyl-2-piperidone, N-methyl-6-methyl-2-piperidone, N-methyl-3-ethyl-2-piperidone wait.

Examples of the organosulfur compound include dimethyl sulfoxide, diethyl sulfoxide, diphenylene sulfone, 1-methyl-1-oxosulfolane, 1-phenyl- 1-Oxysulfone etc.

Various aprotic organic compounds may be used alone or in combination of two or more, or may be mixed with other solvent components that do not interfere with the object of the present invention and used as the aprotic organic solvent.

Preferred solvents among the various aprotic organic solvents are N-alkylcaprolactam and N-alkylpyrrolidone, and a particularly preferred solvent is N-methyl-2-pyrrolidone (NMP).

The amount of the organic solvent used for washing is not particularly limited, and the number of times of washing is also not particularly limited, but preferably 2 or more times.

Washing is preferably performed under inert gas such as nitrogen or argon.

By drying the washed lithium sulfide at a temperature above the boiling point of the aprotic organic solvent used in the washing, under the flow of an inert gas such as nitrogen, under normal pressure or reduced pressure, drying for more than 5 minutes, preferably about 2 to 5 minutes. More than 3 hours, just can obtain the high-purity lithium sulfide used in the present invention.

By using the solid electrolyte of the present invention having excellent characteristics as described above, an all-solid lithium battery excellent in long-term stability can be obtained.

Examples of the negative electrode active material of the all-solid lithium battery of the present invention include carbon, indium, lithium, LiAl, LiWO ₂ , LiMoO ₂ , LiTiS ₂ , and the like, preferably indium.

In addition, examples of the positive electrode active material include metal acid lithium salts such as LiCoO ₂ , LiNiO ₂ , and LiMn ₂ O ₄ , MnO ₂ , V ₂ O ₅ , and the like, among which LiCoO ₂ is preferable.

As a method of manufacturing an all-solid lithium battery using the lithium ion conductive solid electrolyte obtained by the method of the present invention, conventionally known methods can be used.

For example, in an all-solid lithium battery consisting of a sealing plate, an insulating filler, a plate group, a positive plate, a positive lead, a negative plate, a negative lead, a solid electrolyte, and an insulating ring in a battery case, the solid electrolyte can be placed in a thin sheet Forming, packing and use.

Any shape of the all-solid lithium battery can be used, such as a coin type, a button type, a sheet type, a laminated type, a cylindrical type, a flat type, a square shape, a large shape used in electric vehicles, and the like.

Example

Hereinafter, the present invention will be described in more detail using examples and comparative examples, but the present invention is not limited by these examples.

Reference example 1

(1) Manufacture of lithium sulfide

Lithium sulfide is produced according to the first method (two-step method) of JP-A-7-330312.

Specifically, in a 10-liter autoclave equipped with stirring blades, 3326.4 g (33.6 moles) of N-methyl-2-pyrrolidone (NMP) and 287.4 g (12 moles) of lithium hydroxide were added, and the temperature was raised to 130 ℃.

After the temperature was raised, hydrogen sulfide was blown into the liquid at a supply rate of 3 liters/minute for 2 hours.

Next, the temperature of the reaction solution was raised under nitrogen gas flow (200 cm ³ /min), and part of the reacted hydrogen sulfide was dehydrosulfurized.

As the temperature rises, by-produced water due to the reaction of hydrogen sulfide and lithium hydroxide begins to evaporate, and the water is condensed by the condenser and discharged outside the system.

While the temperature of the reaction solution rose while distilling water out of the system, the temperature rise was stopped when it reached 180° C., and the temperature was kept constant.

After the hydrogen sulfide removal reaction was completed (about 80 minutes), the reaction was terminated to obtain lithium sulfide.

(2) Refining of lithium sulfide

After decanting NMP in 500 mL of the slurry reaction solution (NMP-lithium sulfide slurry) obtained in (1), 100 mL of dehydrated NMP was added and stirred at 105° C. for about 1 hour.

NMP was decanted while maintaining the temperature.

Next, 100 mL of NMP was added, stirred at 105° C. for about 1 hour, and the NMP was decanted while maintaining the temperature, and the same operation was repeated four times in total.

After the decantation was completed, it was dried under reduced pressure at 230° C. for 2 hours to obtain high-purity lithium sulfide.

Example 1

0.2903g (0.00632 mole) of high-purity lithium sulfide (Li ₂ S) of reference example 1, 0.3240g (0.00272 mole) of diboron trisulfide (B ₂ S ₃ ) and lithium silicate (Li ₄ SiO ₄ ) 0.0562g (0.00047 mol) was thoroughly mixed in a mortar, granulated, put into a carbon-coated quartz glass tube, and vacuum-sealed.

Then, it was charged into a vertical reaction furnace, and the temperature was raised to 800° C. over 4 hours, and a melting reaction was performed at this temperature for 2 hours.

After the reaction, the quartz tube was plunged into ice water for rapid cooling.

The quartz tube was opened, and X-ray diffraction was performed on the powder sample of the obtained molten reactant (sulfide-based glass). As a result, the peaks of lithium sulfide, diboron trisulfide, and lithium silicate disappeared, and it was confirmed that a vitrified.

The powder samples were heat treated at 215°C for 30 minutes.

X-ray diffraction was performed on the obtained powder sample of the heat-treated product (sulfide-based crystallized glass), and as a result, it was confirmed that a part of crystallization occurred (see FIG. 1 ).

In addition, the electrical conductivity of the powder sample of the heat-treated product was measured by AC impedance method. As a result, the ion conductivity at room temperature was 10.1×10 ^-4 S/cm.

Similarly, X-ray diffraction was performed on a powder sample of the molten reactant (before heat treatment) (see FIG. 1 ).

In addition, the electrical conductivity was measured, and as a result, the ion conductivity at room temperature was 3.5× ^{10 −4 S} /cm.

Table 1 shows the obtained results. In addition, in Table 1, "untreated" means before heat treatment.

Example 2

Reaction and operation were carried out in the same manner as in Example 1 except that lithium silicate was replaced with 0.0336 g (0.00028 mol).

Table 1 shows the obtained results.

Example 3

Reaction and operation were carried out in the same manner as in Example 1 except that lithium silicate was replaced with 0.0456 g (0.00038 mol).

Table 1 shows the obtained results.

Example 4

Reaction and operation were carried out in the same manner as in Example 1 except that lithium silicate was replaced with 0.0692 g (0.00058 mol).

Table 1 shows the obtained results.

Example 5

Reaction and operation were carried out in the same manner as in Example 1 except that lithium silicate was replaced with 0.0815 g (0.000688 mol).

Table 1 shows the obtained results. In addition, the term "untreated" in Table 1 means before heat treatment.

Example 6

Using the heat-treated product (sulfide-based crystallized glass) synthesized in Example 1, the cyclic voltammetry curve was measured in the range of -0.5 to 10V at a scan rate of 10 mV/sec.

The results are shown in FIG. 2 .

Also, the vertical axis represents current/A, and the horizontal axis represents potential (VvsLi ⁺ /Li).

Example 7

Using the heat-treated product (sulfide-based crystallized glass) synthesized in Example 4, lithium cobaltate (LiCoO ₂ ) as a positive electrode active material, and indium (In) as a negative electrode active material, a lithium battery was produced as follows, and evaluated its battery characteristics.

Using the negative electrode active material (56.6 mg) and the positive electrode active material (11.9 mg), the heat-treated product (165.5 mg) was sandwiched between them to make three layers of pellets to form a measurement unit cell. .

The upper limit voltage of charge and discharge was set to 3.7 V, the lower limit voltage was set to 2 V, and the current density was set to 12.7 μA·cm ⁻² for the measurement cell, and charge and discharge were studied.

The obtained results are shown in FIG. 3 .

Furthermore, the vertical axis represents the cell voltage/V, and the horizontal axis represents the capacity/mAh·g ^-1 relative to 1 g of lithium cobaltate.

Comparative example 1

The reaction and operation were carried out in the same manner as in Example 1 except that lithium silicate was not added.

Table 1 shows the obtained results.

Comparative example 2

Reaction and operation were carried out in the same manner as in Example 1, except that lithium silicate was not added, high-purity lithium sulfide was 0.3489 g (0.00759 mol), and diboron trisulfide was 0.3396 g (0.00288 mol).

Table 1 shows the obtained results.

Comparative example 3

Reaction and operation were carried out in the same manner as in Example 1, except that lithium silicate was not added, high-purity lithium sulfide was 0.2651 g (0.00577 mol), and diboron trisulfide was 0.3349 g (0.00284 mol).

Table 1 shows the obtained results.

Table 1

Example 8

0.2903g (0.00632 moles) of high-purity lithium sulfide (Li ₂ S) of Reference Example 1, 0.3204g (0.00272 moles) of diboron trisulfide (B ₂ S ₃ ) and 0.0338g (0.00068 moles) of lithium borate (LiBO ₂ ) ) were thoroughly mixed in a mortar, granulated, put into a carbon-coated quartz glass tube, and vacuum-sealed.

Then, it was charged into a vertical reaction furnace, and the temperature was raised to 800° C. over 4 hours, and a melting reaction was performed at this temperature for 2 hours.

After the reaction, the quartz tube was plunged into ice water for rapid cooling.

The quartz tube was opened, and X-ray diffraction was performed on the obtained powder sample of the molten reactant (sulfide-based glass). As a result, no clear diffraction line was observed, and vitrification of the sample was confirmed.

The electrical conductivity of this powder sample of the molten reactant was measured by an AC impedance method, and as a result, the ion conductivity at room temperature was 6.7×10 ^-4 S/cm.

Table 2 shows the obtained results. In addition, in Table 2, "untreated" means before heat treatment.

Example 9

Reaction and operation were carried out in the same manner as in Example 8, except that lithium borate was replaced with 0.0443 g (0.00089 mol).

As a result of X-ray diffraction of the obtained powder sample of the molten reactant (sulfide-based glass), no clear diffraction line was observed, and it was confirmed that the sample was vitrified.

The electrical conductivity of the powder sample of the molten reactant was measured, and as a result, the ion conductivity at room temperature was 9.5×10 ^-4 S/cm.

Table 2 shows the obtained results.

Example 10

Reaction and operation were carried out in the same manner as in Example 8, except that lithium borate was replaced by lithium phosphate (Li ₃ PO ₄ ) and the amount used was replaced by 0.0534 g (0.000475 mol).

As a result of X-ray diffraction of the obtained powder sample of the molten reactant (sulfide-based glass; before heat treatment), no clear diffraction line was observed, and it was confirmed that the sample was vitrified.

As a result of measuring the electrical conductivity of the powder sample of the molten reactant, the ion conductivity at room temperature was 8.1×10 ^-4 S/cm.

A powder sample of the molten reactant (before heat treatment) was heat treated at 230° C. for 30 minutes.

The electrical conductivity of the obtained powder sample of the heat-treated product (sulfide-based crystallized glass) was measured. As a result, the ion conductivity at room temperature was 22.0×10 ^-4 S/cm.

Table 2 shows the obtained results.

Example 11

Reaction and operation were carried out in the same manner as in Example 8, except that lithium borate was replaced with lithium phosphate (Li ₃ PO ₄ ) and the amount used was replaced with 0.0787 g (0.00068 mol).

As a result of X-ray diffraction of the obtained powder sample of the molten reactant (sulfide-based glass; before heat treatment), no clear diffraction line was observed, and it was confirmed that the sample was vitrified.

The electrical conductivity of the powder sample of the molten reactant was measured, and as a result, the ion conductivity at room temperature was 8.0×10 ^-4 S/cm.

A powder sample of the molten reactant (before heat treatment) was heat treated at 230° C. for 30 minutes.

The electrical conductivity of the obtained powder sample of the heat-treated product (sulfide-based crystallized glass) was measured. As a result, the ion conductivity at room temperature was 24.0×10 ^-4 S/cm.

Table 2 shows the obtained results.

Example 12

Reaction and operation were carried out in the same manner as in Example 8, except that lithium borate was replaced by lithium phosphate (Li ₃ PO ₄ ) and the amount used was replaced by 0.0324 g (0.00028 mol).

As a result of X-ray diffraction of the obtained powder sample of the molten reactant (sulfide-based glass; before heat treatment), no clear diffraction line was observed, and it was confirmed that the sample was vitrified.

The electrical conductivity of this powder sample of the molten reactant was measured, and as a result, the ion conductivity at room temperature was 6.1×10 ^-4 S/cm.

A powder sample of the molten reactant (before heat treatment) was heat treated at 230° C. for 30 minutes.

The electrical conductivity of the obtained powder sample of the heat-treated product (sulfide-based crystallized glass) was measured. As a result, the ion conductivity at room temperature was 19.0×10 ^-4 S/cm.

Table 2 shows the obtained results. In addition, the term "untreated" in Table 2 means before heat treatment.

Table 2

Industrial Utilization Possibility

The lithium ion conductive solid electrolyte obtained by the method of the present invention can be used as a complete battery for portable information terminals, portable electronic equipment, household small power storage devices, two-wheeled motorcycles with electric motors as the power source, electric vehicles, and compound electric vehicles. Solid lithium batteries are used, however, it is not particularly limited to them.

Claims (8)

1. lithium-ion-conducting solid electrolyte, it is to contain 60～80 moles of % lithium sulfide (Li ₂S), 1～15 mole of % is with Li _aMO _bCompound, the surplus of expression are boron sulfide (B ₂S ₃) raw mix frit reaction thing chilling and sulfide-based glass; The sulfide-based sintered glass ceramics that this sulfide-based glass heat processing is got; Or the mixture of the ratio arbitrarily of above-mentioned sulfide-based glass and above-mentioned sulfide-based sintered glass ceramics,

Wherein, M represents to be selected from the element in phosphorus (P), silicon (Si), aluminium (Al), boron (B), sulphur (S), germanium (Ge), gallium (Ga), the indium (In), and a and b represent 1～10 number independently.

2. a lithium-ion-conducting solid electrolyte is characterized in that, has lithium sulfide (Li ₂S): with Li _aMO _bThe mole % ratio of the compound of expression be 60～80: 1～15 and surplus be boron sulfide (B ₂S ₃) composition.

Wherein, M represents to be selected from the element in phosphorus (P), silicon (Si), aluminium (Al), boron (B), sulphur (S), germanium (Ge), gallium (Ga), the indium (In), and a and b represent 1～10 number independently.

3. a method for producing lithium ion conductive solid electrolyte is characterized in that, will have lithium sulfide (Li2S): with Li _aMO _bThe mole % ratio of the compound of expression be 60～80: 1～15 and surplus be boron sulfide (B ₂S ₃) the sulfide-based glass of composition under 100～350 ℃, heat-treat.

Wherein, M represents to be selected from the element in phosphorus (P), silicon (Si), aluminium (Al), boron (B), sulphur (S), germanium (Ge), gallium (Ga), the indium (In), and a and b represent 1～10 number independently.

According in the claim 3 record method for producing lithium ion conductive solid electrolyte, wherein, with general formula Li _aMO _bThe compound of expression is selected from lithium metasilicate, lithium borate, lithium phosphate.

5. according to the method for producing lithium ion conductive solid electrolyte of claim 3 or 4 records, wherein, replace boron sulfide, and use the boron of suitable mol ratio and the mixture of element sulphur.

6. one kind is utilized any lithium-ion-conducting solid electrolyte that the manufacture method of being put down in writing obtains in the claim 3～5.

7. secondary lithium batteries solid electrolyte that uses claim 1,2 or 6 lithium-ion-conducting solid electrolytes of being put down in writing to form.

8. all-solid lithium battery that the secondary lithium batteries solid electrolyte that uses in the claim 7 record forms.

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