JP2012138346A - Composition including lithium ion conductive solid electrolyte and method for preserving the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composition capable of being preserved for a long period while a sulfide-based solid electrolyte is dispersed, and including a binder dissolved therein.SOLUTION: The composition includes: a lithium ion conductive solid electrolyte containing lithium and sulfur; a nitrile compound represented as R-CN; and a binder. The nitrile compound is liquid at a temperature of 25°C and a pressure of 101,325 Pa, and satisfies the following relationships: 0.05≤(Y+Z)/(X+Y+Z)≤0.75 and Z/(Y+Z)≤0.5. R represents a linear or branched hydrocarbon group having 3 or more and 40 or less carbon atoms, or a group having a cyclic structure having 3-10 carbon atoms, and may include a hydrocarbon group having 1 or more and 20 or less carbon atoms and/or a group having a cyclic structure having 3-10 carbon atoms. X represents the weight of the nitrile compound, Y represents the weight of the lithium ion conductive solid electrolyte, and Z represents the weight of the binder.

Description

  The present invention relates to a composition containing a lithium ion conductive solid electrolyte and a storage method thereof.

With the recent development of mobile communication and information electronic devices, the demand for high-capacity and lightweight lithium secondary batteries tends to increase. Most electrolytes exhibiting high lithium ion conductivity at room temperature are liquids, and many of the commercially available lithium ion secondary batteries use organic electrolytes.
The lithium secondary battery using this organic electrolyte has a risk of leakage, ignition and explosion, and a battery with higher safety is desired. An all-solid battery using a solid electrolyte has a feature that electrolyte leakage and ignition hardly occur. However, the ionic conductivity of the solid electrolyte is generally low and it is difficult to put it to practical use.

In a lithium secondary battery using a solid electrolyte, a lithium ion conductive ceramic based on Li ₃ N is conventionally known as a solid electrolyte exhibiting high ion conductivity of 10 ⁻³ Scm ⁻¹ at room temperature. However, since the decomposition voltage is low, a battery that operates at 3 V or more cannot be constructed.

As a sulfide-based solid electrolyte, 10 ⁻⁴ Scm ⁻¹ solid electrolyte is disclosed in Patent Document 1, and in Patent Document 2, an electrolyte synthesized from Li ₂ S and P ₂ S ₅ is similarly 10 ^-4 Scm- ¹ ion conductivity is disclosed. Furthermore, the Li ₂ S and _P 2 _{S 5} in Patent Document 3 68 to 74 mol%: 26-32 mol% of the combined sulfide-based crystallized glass ¹⁰ -3 ^{Scm -1} single ion conductivity at a ratio of Realized.

  The electrolyte has the disadvantage that it is hydrolyzed when it comes into contact with moisture, resulting in a decrease in ionic conductivity. Therefore, a method of handling the electrolyte at a dew point of −40 ° C. or less has been developed (Patent Document 4).

  However, in order to store the electrolyte at a dew point of −40 ° C. or lower, it is necessary to store it in a highly airtight container or in a nonpolar solution.

Further, when the electrolyte layer of a lithium ion battery is manufactured by a coating method, it is manufactured using a slurry in which the electrolyte is dispersed in a liquid. However, since the electrolyte is an inorganic substance, an organic binder (hereinafter referred to as “binder”) is used. , Referred to as “binder”), the electrolyte layer does not adhere to the electrode layer. Moreover, in order to function as a binder, the binder had to be dissolved in the liquid.
However, the nonpolar solution has a drawback that the binder does not dissolve.

JP-A-4-202024 JP 2002-109955 A JP 2005-228570 A JP 2002-212705 A

  An object of the present invention is to provide a composition that can be stored for a long time in a state where a sulfide-based solid electrolyte is dispersed and in which a binder is dissolved.

According to the present invention, the following compositions and the like are provided.
1. Lithium ion conductive solid electrolyte containing lithium and sulfur,
A nitrile compound represented by formula (1), and a binder,
The nitrile compound is liquid at a temperature of 25 ° C. and a pressure of 101325 Pa.
A composition satisfying the formulas (I) and (II).
R-CN (1)
(In Formula (1), R is a linear or branched hydrocarbon group having 3 to 40 carbon atoms, or a group having a cyclic structure having 3 to 10 carbon atoms, and carbonization having 1 to 20 carbon atoms. A hydrogen group and / or a group having a cyclic structure having 3 to 10 carbon atoms may be included.)
0.05 ≦ (Y + Z) / (X + Y + Z) ≦ 0.75 (I)
Z / (Y + Z) ≦ 0.5 (II)
(In formulas (I) and (II), X represents the weight of the nitrile compound, Y represents the weight of the lithium ion conductive solid electrolyte, and Z represents the weight of the binder.)
2. 2. The composition according to 1, wherein the lithium ion conductive solid electrolyte is pulverized electrolyte particles.
3. The composition according to 1 or 2, wherein the water content of the nitrile compound is 50 ppm or less.
4). The composition in any one of 1-3 containing an active material.
5. A method for storing a lithium ion conductive solid electrolyte, comprising storing a lithium ion conductive solid electrolyte containing lithium and sulfur in a nitrile compound represented by formula (1) that is liquid at a temperature of 25 ° C. and a pressure of 101325 Pa.
R-CN (1)
(R in Formula (1) is a linear or branched hydrocarbon group having 3 to 40 carbon atoms, or a group having a cyclic structure having 3 to 10 carbon atoms, and having 1 to 20 carbon atoms. A hydrogen group and / or a group having a cyclic structure having 3 to 10 carbon atoms may be included.)
6). Lithium ion conductive solid electrolyte and binder containing lithium and sulfur are stored in a nitrile compound represented by formula (1) which is liquid at a temperature of 25 ° C. and a pressure of 101325 Pa. .
R-CN (1)
(R in Formula (1) is a linear or branched hydrocarbon group having 3 to 40 carbon atoms, or a group having a cyclic structure having 3 to 10 carbon atoms, and having 1 to 20 carbon atoms. A hydrogen group and / or a group having a cyclic structure having 3 to 10 carbon atoms may be included.)

  ADVANTAGE OF THE INVENTION According to this invention, the composition which can be preserve | saved for a long time in the state which disperse | distributed sulfide type solid electrolyte, and the binder has melt | dissolved can be provided.

The composition of this invention contains the lithium ion conductive solid electrolyte (henceforth a solid electrolyte) containing lithium and sulfur, the nitrile compound shown by Formula (1), and a binder.
R-CN (1)
In formula (1), R is a linear or branched hydrocarbon group having 3 to 40 carbon atoms, or a group having a cyclic structure having 3 to 10 carbon atoms, and a hydrocarbon having 1 to 20 carbon atoms. A group and / or a group having a cyclic structure having 3 to 10 carbon atoms may be included.
The nitrile compound is a liquid in an environment at a temperature of 25 ° C. and a pressure of 101325 Pa (atmospheric pressure).

The composition of the present invention satisfies the formulas (I) and (II).
0.05 ≦ (Y + Z) / (X + Y + Z) ≦ 0.75 (I)
Z / (Y + Z) ≦ 0.5 (II)
In the formulas (I) and (II), X represents the weight of the nitrile compound, Y represents the weight of the solid electrolyte, and Z represents the weight of the binder.

1. Solid electrolyte The solid electrolyte may be glass or glass ceramics.
The solid electrolyte is preferably in the form of particles. The particle size is not particularly limited and is, for example, from 0.1 μm to 100 μm. The particle size can be measured by the method described in the examples.

(1) Raw material The solid electrolyte contains Li and S. The solid electrolyte preferably contains at least one element selected from the group consisting of P, B, Si, Ge, and Al, and an Li element and an S element.
In particular, it is preferable that Li, S, and P are included, and the ratio of Li, S, and P is 20 to 42:11 to 20:47 to 60 (mol%).

When the sulfide-based solid electrolyte is produced from lithium sulfide and diphosphorus pentasulfide, the mixing molar ratio is usually 50:50 to 80:20, preferably 60:40 to 75:25. Particularly preferably, it is about Li ₂ S: P ₂ S ₅ = 68: 32 to 74:26 (molar ratio).

(2) Glass ceramics The crystal structure is preferably at least one crystal phase selected from the group consisting of Li ₇ PS ₆ , Li ₄ P ₂ S ₆ , Li ₃ PS ₄ and Li ₇ P ₃ S ₁₁ , more preferably. A Li ₇ P ₃ S ₁₁ crystal phase is preferred.
If it is the said crystal structure, ion conductivity is higher than glass, and if a lithium ion battery is manufactured using the glass ceramic which has this crystal structure, a high performance lithium ion battery will be manufactured.

(3) Manufacturing Method of Glass / Glass Ceramics Glass / glass ceramics are manufactured with a dew point kept at −40 ° C. or lower, but are preferably manufactured under an inert gas stream. This is because lithium sulfide, diphosphorus pentasulfide, glass and glass ceramics, which are raw materials for glass, react with moisture to cause hydrolysis.

(I) Preparation of glass below, for explaining a method for manufacturing a glass solid electrolytes in the case of using _P 2 _{S 5} and Li ₂ S as a raw material.
Examples of the method for producing a glass solid electrolyte include a melt quenching method and a mechanical milling method (MM method).
In the case of the melt quenching method, a predetermined amount of P ₂ S ₅ and Li ₂ S are mixed in a mortar, and the pellets are placed in a carbon-coated quartz tube and sealed in a vacuum. After reacting under predetermined reaction conditions (usually 400 ° C. to 1000 ° C., 0.1 hour to 12 hours), a sulfide-based glass solid electrolyte is obtained by putting in ice and rapidly cooling.
In addition, since the solid electrolyte manufactured by the rapid cooling method is a lump and is not in the form of particles, it may be stored in a lump state or may be pulverized and stored as described below.

In the case of the MM method, a sulfide-based glass solid electrolyte is obtained by mixing a predetermined amount of P ₂ S ₅ and Li ₂ S in a mortar and reacting them by a mechanical milling method. Li ₂ S is preferably highly pure.
In the MM method, various types such as a rotating ball mill, a rolling ball mill, a vibrating ball mill, and a planetary ball mill can be used. As conditions for the MM method, for example, when a planetary ball mill is used, the rotation speed may be several tens to several hundreds of revolutions / minute, and the treatment may be performed for 0.5 hours to 100 hours.

(Ii) Manufacturing Method of Glass Ceramics The heat treatment for crystallizing the glass is performed at a temperature of 230 ° C. or higher because the glass transition temperature of the sulfide-based glass is 230 ° C.
Crystallization occurs by heating at a temperature range of 230 ° C. to 350 ° C. for 0.1 hours to 24 hours, more preferably 0.5 hours to 12 hours, and even more preferably 2 hours to 5 hours.

(3) Grinding of glass / glass ceramics The solid electrolyte may be obtained by grinding the glass / glass ceramics. The pulverization is not particularly limited as long as it is a method capable of pulverizing glass and glass ceramics.

2. Nitrile Compound The nitrile compound is represented by the formula (1) and is a liquid in an environment having a temperature of 25 ° C. and a pressure of 101325 Pa.
R-CN (1)
R in the formula (1) is a linear or branched hydrocarbon group having 3 to 40 carbon atoms, or a group having a cyclic structure having 3 to 10 carbon atoms, and a hydrocarbon having 1 to 20 carbon atoms. A group and / or a group having a cyclic structure having 3 to 10 carbon atoms may be included. Such a nitrile compound (solvent) can dissolve the following binder without deteriorating the solid electrolyte.

The hydrocarbon group having 3 to 40 carbon atoms is preferably a linear or branched (more preferably branched) alkyl group having 3 to 10 (more preferably 3 to 6) carbon atoms.
The cyclic structure having 3 to 10 carbon atoms is preferably a benzene ring, and the group having a cyclic structure having 3 to 10 carbon atoms is, for example, a phenyl group, alkyl (having 1 to 10 carbon atoms, preferably 1 to 6 carbon atoms). ) A phenyl group or a phenylalkyl (C1-C10, preferably C1-C6) group.

式（２）において、Ｒ_１は、炭素数１以上２０以下のアルキル基、フェニル基、又は炭素数３以上１０以下のシクロアルキル基である。Ｒ_２、Ｒ_３、Ｒ_４は、水素、炭素数１以上２０以下のアルキル基、フェニル基、又は炭素数３以上１０以下のシクロアルキル基であり、Ｒ_１〜Ｒ_４は同一でも異なっていてもよい。
また、Ｒ_３とＲ_４が水素である場合には、炭素数はＲ_１＋Ｒ_２≧３である。 It is preferable that Formula (1) is Formula (2).

In Formula (2), R ₁ is an alkyl group having 1 to 20 carbon atoms, a phenyl group, or a cycloalkyl group having 3 to 10 carbon atoms. R ₂ , R ₃ , and R ₄ are hydrogen, an alkyl group having 1 to 20 carbon atoms, a phenyl group, or a cycloalkyl group having 3 to 10 carbon atoms, and R _{1 to} R ₄ are the same or different. Also good.
When R ₃ and R ₄ are hydrogen, the carbon number is R ₁ + R ₂ ≧ 3.

式（３）において、Ｒ_１２及びＲ_１３はメチル基又は水素であり、Ｒ_１１は、炭素数１〜１０のアルキル基又はフェニル基である。
Ｒ_１１がフェニル基である場合には、Ｒ_１２及びＲ_１３が水素であること、即ちＲ_１１、Ｒ_１２及びＲ_１３で示される置換基は、無置換のフェニル基であることがより好ましい。
Ｒ_１１がフェニル基である場合には、式(３)中のCN、Ｒ_１２及びＲ_１３はそれぞれフェニル基の異なる位に置換される。 More preferably, Formula (1) is represented by the following Formula (3).

In Formula (3), R ₁₂ and R ₁₃ are a methyl group or hydrogen, and R ₁₁ is an alkyl group having 1 to 10 carbon atoms or a phenyl group.
When R ₁₁ is a phenyl group, R ₁₂ and R ₁₃ are preferably hydrogen, that is, the substituent represented by R ₁₁ , R ₁₂ and R ₁₃ is more preferably an unsubstituted phenyl group.
When R ₁₁ is a phenyl group, CN, R ₁₂ and R ₁₃ in formula (3) are each substituted at a different position of the phenyl group.

Specific examples of the nitrile compound include benzonitrile, isobutyronitrile, and isovaleronitrile.
The water content in the nitrile compound is preferably 50 ppm or less. When the water content is 50 ppm or less, the deterioration of the electrolyte can be further suppressed. The moisture content is measured with a Karl Fischer moisture meter.

3. Binder The binder only needs to be one that does not deteriorate due to the above solution. The binder refers to a binder having a function of bringing the electrolyte particles into close contact with the electrode layer and bringing the electrolyte particles into close contact with each other.
As the binder, polyethylene and vinylidene fluoride are suitable,
Examples thereof include polyvinylidene fluoride, polyethylene glycol, polyethylene oxide, polyacrylonitrile, polymethyl methacrylate, polysiloxy acid, vinylidene fluoride-hexafluoropropylene copolymer, and the like.

Preferably, the binder is a polymer having a unit of the following formula (10) or a unit of the formula (11).
_{- [OCH 2 CH 2] n} - ··· (10)
_{- [CH 2 -CF 2] n} - ··· (11)
The weight average molecular weight is preferably 10,000 to 100,000. The weight average molecular weight is measured by gel permeation chromatography (GPC).

More preferably, it is represented by the following formula.
_{R 20 - [OCH 2 CH 2} ] n -H
R ₂₁ — [CH ₂ —CF ₂ ] _n —R _{21 ′}
R ₂₀ , R ₂₁ and R _{21 ′} are each a linear or branched hydrocarbon group, a group having a cyclic structure, or a functional group, and the hydrocarbon group and the group having a cyclic structure may include a functional group. Good.

4). Ratio of each component The ratio of the solid electrolyte and the nitrile compound (solvent) is not particularly limited. For example, when storing in a container, the solid electrolyte may be immersed in the solvent.

When the binder and the solid electrolyte are stored together, the solid electrolyte and the binder need only be immersed in a solvent.
For example, it is preferable to follow the following formula.
0.05 ≦ (Y + Z) / (X + Y + Z) ≦ 0.75
Z / (Y + Z) ≦ 0.5
In the formula, X represents the weight of the solvent, Y represents the weight of the solid electrolyte, and Z represents the weight of the binder.

If (Y + Z) / (X + Y + Z) is less than 0.05, it may become liquid and cannot be applied. Further, if (Y + Z) / (X + Y + Z) exceeds 0.75, the amount of solid components increases, and it may be difficult to form an electrolyte layer by a coating method.
Here, the units of X, Y and Z are the same. If the unit of X is g, the unit of Y and Z is also g.

5. Other Components The composition of the present invention may contain an active material.
The active material may be dissolved or dispersed in the nitrile compound.

(1) Active material The active material should just be what does not deteriorate with the said solution.
The active material includes a positive electrode active material used for manufacturing a positive electrode and a negative electrode active material used for manufacturing a negative electrode.
As the positive electrode active material, a metal oxide capable of insertion / extraction of lithium ions and a material known as a positive electrode active material in the battery field can be used.

For example, in the sulfide system, titanium sulfide (TiS ₂ ), molybdenum sulfide (MoS ₂ ), iron sulfide (FeS, FeS ₂ ), copper sulfide (CuS), nickel sulfide (Ni ₃ S ₂ ), etc. can be used. TiS ₂ is preferred. These substances can be used alone or in combination of two or more.

Moreover, as an oxide type, Preferably the thing of a following formula is mentioned.
LiNi _x M _1-x O _{2
LiNi a Co b Al 1-a} -b O 2
(Wherein x is a number satisfying 0.1 <x <0.9, M is an element selected from the group consisting of Fe, Co, Mn and Al, and 0 ≦ a ≦ 1, 0 ≦ b ≦ 1)

Also, for example, bismuth oxide (Bi ₂ O ₃ ), bismuth leadate (Bi ₂ Pb ₂ O ₅ ), copper oxide (CuO), vanadium oxide (V ₆ O ₁₃ ), lithium cobaltate (LiCoO ₂ ), nickel acid Lithium (LiNiO ₂ ), lithium manganate (LiMn ₂ O ₄ ), olivine-type lithium iron phosphate (LiFePO ₄ ), nickel-manganese oxide (LiNi _0.5 Mn _0.5 O ₂ ), nickel-aluminum - cobalt oxide _{(LiNi 0.8 Co 0.15 Al 0.05 O} 2), nickel - manganese - cobalt oxide _{(LiNi 0.33 Co 0.33 Mn 0.33 O} 2) or the like can be used In particular, LiCoO ₂ and LiNi _0.8 Co _0.15 Al _0.05 O ₂ are suitable. These substances can be used alone or in combination of two or more.

It is also possible to use a mixture of the above sulfides and oxides. In addition to the above, niobium selenide (NbSe ₃ ) can also be used.
A material whose surface is coated with an oxide, sulfide or the like can be suitably used as necessary.

As the negative electrode active material, a material capable of inserting and desorbing lithium ions, and a known negative electrode active material in the battery field can be used.
For example, carbon materials, specifically artificial graphite, graphite carbon fiber, resin-fired carbon, pyrolytic vapor-grown carbon, coke, mesocarbon microbeads (MCMB), furfuryl alcohol resin-fired carbon, polyacene, pitch-based carbon Examples thereof include fibers, vapor-grown carbon fibers, natural graphite and non-graphitizable carbon, and artificial graphite is particularly preferable.

An alloy combined with a metal itself such as metallic lithium, metallic indium, metallic aluminum, metallic silicon, metallic tin, or another element or compound can be used as the negative electrode active material.
These negative electrode active materials can be used individually by 1 type or in combination of 2 or more types.

6). The preservation | save method of this invention The preservation | save method of the lithium ion conductive solid electrolyte of this invention preserve | saves said solid electrolyte in said nitrile compound.
It should be noted that the amount of the nitrile compound used for storage should be such that the lithium ion conductive solid electrolyte is immersed and does not come into contact with air.
Therefore, the amount of the nitrile compound varies depending on the container to be stored.

If the sulfide-based solid electrolyte is in the form of particles, according to the first storage method, the sulfide-based solid electrolyte particles are dispersed in the nitrile compound. An electrolyte layer can be produced by a coating method as a slurry.
In addition, you may preserve | save by adding said binder to a solid electrolyte and a nitrile compound.

  As the storage container, a normal storage container can be used, but a container having high airtightness is preferable. Moreover, what can be filled with inert gas, such as argon gas, in the space which is not filled with the solution is preferable.

Production Example 1
The following was performed in an atmosphere kept at a dew point of −60 ° C. or lower.
(1) Production of lithium sulfide Lithium sulfide was produced according to the method of the first aspect (two-step method) of JP-A-7-330312. Specifically, N-methyl-2-pyrrolidone (NMP) 3326.4 g (33.6 mol) and lithium hydroxide 287.4 g (12 mol) were charged into a 10 liter autoclave equipped with a stirring blade, and 300 rpm, 130 The temperature was raised to ° C. After the temperature rise, hydrogen sulfide was blown into the liquid at a supply rate of 3 liters / minute for 2 hours.

  Subsequently, this reaction solution was heated in a nitrogen stream (200 cc / min) to dehydrosulfide a part of the reacted hydrogen sulfide. As the temperature increased, water produced as a by-product due to the reaction between hydrogen sulfide and lithium hydroxide started to evaporate, but this water was condensed by the condenser and extracted out of the system. While water was distilled out of the system, the temperature of the reaction solution rose, but when the temperature reached 180 ° C., the temperature increase was stopped and the temperature was kept constant. After the dehydrosulfurization reaction was completed (about 80 minutes), the reaction was completed to obtain lithium sulfide.

(2) Purification of lithium sulfide After decanting NMP in the 500 mL slurry reaction solution (NMP-lithium sulfide slurry) obtained in (1) above, 100 mL of dehydrated NMP was added and stirred at 105 ° C. for about 1 hour. . NMP was decanted at that temperature. Further, 100 mL of NMP was added, stirred at 105 ° C. for about 1 hour, NMP was decanted at that temperature, and the same operation was repeated a total of 4 times. After completion of the decantation, lithium sulfide was dried at 230 ° C. (temperature higher than the boiling point of NMP) under a nitrogen stream for 3 hours under normal pressure.

(3) Manufacture of sulfide-based solid electrolyte (glass) 16.27 g of lithium sulfide manufactured in the above (2) and 33.73 g of P ₂ S ₅ (manufactured by Aldrich) were mixed with 500 ml of planetary ball mill (PM-400 manufactured by Lecce). It was put in a container (Li ₂ S 70 mol%: P ₂ S ₅ 30 mol%), and 175 alumina balls having a diameter of 10 mm were further added and fixed with a jig.
Give 70Li _{2 S-30P 2} S ₅ based sulfide solid electrolyte (glass) by 36 hours in this state.

The method for measuring the particle size of glass is as follows when the laser diffraction particle size distribution analyzer is Mastersizer 2000 manufactured by Malvern Instruments Ltd.
First, 110 ml of dehydrated toluene (Wako Pure Chemicals, product name: special grade) was placed in the dispersion tank of the apparatus, and 6% of dehydrated tertiary butyl alcohol (Wako Pure Chemicals, special grade) was added as a dispersant. Added.
Here, the addition of a dispersant to toluene is not to make the “aggregated solid electrolyte particles” in the solid electrolyte-containing composition primary particles (disperse), but in the solid electrolyte-containing composition to be measured. This is to prevent the solid electrolyte particles from aggregating.

  The laser diffraction particle size distribution measurement method can measure the particle size distribution without drying the composition, and measures the particle size distribution by irradiating a particle group in the composition with laser and analyzing the scattered light. be able to.

After sufficiently mixing the above mixture, solid electrolyte particles are added and the particle size is measured. The amount of the solid electrolyte particles added is adjusted so that the laser scattering intensity corresponding to the particle concentration falls within a specified range (10 to 20%) on the operation screen specified by the master sizer 2000. If this range is exceeded, multiple scattering may occur, and an accurate particle size distribution may not be obtained. On the other hand, when the amount is less than this range, the SN ratio is deteriorated, and there is a possibility that accurate measurement cannot be performed. In Master Sizer 2000, the laser scattering intensity is displayed based on the addition amount of the solid electrolyte particles. Therefore, the addition amount that falls within the laser scattering intensity may be found.
Although the optimum amount of the solid electrolyte particles varies depending on the concentration of the composition, it is about 10 μL to 200 μL.

  The average particle diameter of the sulfide-based solid electrolyte (glass) was 150 μm (volume basis average, the same applies hereinafter).

(4) glass-ceramics manufacturing the 70Li _{2 S-30P 2} S ₅ based sulfide solid electrolyte (glass) 70Li _{2 S-30P 2} S ₅ system by a heating for 2 hours at 300 ° C. sulfide solid electrolyte (glass ceramics ) The average particle size of the glass ceramics was 100 μm. The ionic conductivity of the glass ceramic was 1.32 × 10 ⁻³ S / cm.

Production Example 2
In the preparation of the solid electrolyte of Production Example 1 (3), Li ₂ S and P ₂ S ₅ (manufactured by Aldrich) were mixed at a molar ratio of 75:25, and 75Li ₂ S-25P ₂ S ₅ system sulfide was mixed. A solid electrolyte (glass) was obtained. The average particle size of the glass was 68 μm.
Incidentally, the raw material ratio of Li ₂ S and _P 2 _{S 5,} except different, was performed in the same manner as in Production Example 1 (3).
The recovery rate of the solid electrolyte glass particles was 82%. In the X-ray diffraction measurement (CuKα: λ = 1.5418４), the peak of the raw material Li ₂ S was not observed, and the halo pattern was attributed to the solid electrolyte glass. . Moreover, the ionic conductivity of the obtained glass particle was 2.29 × 10 ⁻⁴ S / cm.

Example 1
(1) Slurry of solid electrolyte 16.5 g of the glass ceramic of Production Example 1 was transferred to a 45 ml mill pot in which 20 Zr balls having a diameter of 10 mm were previously placed, and subjected to N ₂ bubbling treatment for 24 hours (manufactured by Wako Pure Chemical Industries, Ltd.) (water content) 20 g) was added and sealed (solid content concentration 45 wt%). This was mechanically milled at 370 rpm for 60 minutes to pulverize the glass ceramics to obtain a slurry containing the pulverized glass ceramics.

  The slurry was air-dried and then vacuum-dried at 150 ° C. for 2 hours with a tube heater, and the particle size was measured. The average particle size was 10 μm. The method for measuring the particle size is the same as described above.

(2) Storage of slurry This slurry was stored under the following conditions, and the ionic conductivity was measured.
The slurry was stored in a glove box (dew point −60 ° C., oxygen concentration 0.1 ppm, 25 ° C.) for 0 hour (immediately after MM treatment), 120 hours, and 240 hours.
Thereafter, each slurry was air-dried and then vacuum-dried at 150 ° C. for 2 hours with a tube heater, and the ionic conductivity was measured according to the above method.

The ionic conductivity was as follows.
0 hour: 1.31 × 10 ⁻³ S / cm
120 hours: 1.55 × 10 ⁻³ S / cm
240 hours: 1.61 × 10 ⁻³ S / cm

The ionic conductivity of the sulfide-based solid electrolyte glass ceramic was measured according to the following method.
A sulfide-based solid electrolyte glass ceramic was filled in a tablet molding machine, and a pressure of 4 to 6 MPa was applied to obtain a molded body. Furthermore, a composite material in which carbon and the electrolyte glass ceramic are mixed at a weight ratio of 1: 1 as an electrode is placed on both surfaces of the molded body, and pressure is again applied by a tablet molding machine, whereby a molded body for measuring conductivity (diameter About 10 mm and thickness about 1 mm).
The molded body was subjected to ionic conductivity measurement by AC impedance measurement. The conductivity value was a value at 25 ° C.

  From the above results, it was found that glass ceramics are slow to deteriorate in benzonitrile.

(3) Mixing with Binder When 1.13 g of PEO (polyethylene oxide) polymer (manufactured by Aldrich) was mixed with the slurry immediately after the MM treatment, it was confirmed that the slurry was dissolved in the slurry. In addition, 0.75 g of PVDF-HFP (vinylidene fluoride / hexafluoropropylene copolymer) (binder: manufactured by Arkema, product name: KYNAR2750-01) was mixed with the slurry immediately after the MM treatment and dissolved in the slurry. It was confirmed.

Example 2
(1) Slurry of solid electrolyte 5 g of the glass ceramic of Production Example 1 was transferred to a 45 ml mill pot in which 20 Zr balls having a diameter of 10 mm were previously placed, and subjected to N ₂ bubbling treatment for 24 hours, 15 g of isobutyronitrile (moisture content of 50 ppm or less) Was added and sealed (solid content concentration 25 wt%). This was mechanically milled at 370 rpm for 120 minutes to pulverize the glass ceramics to obtain a slurry containing the pulverized glass ceramics.

  The slurry was air-dried and then vacuum-dried at 150 ° C. for 2 hours with a tube heater, and the particle size was measured. The average particle size was 1 μm. In addition, the measuring method of a particle size is the same as the above.

(2) Storage of slurry The slurry was stored in the same manner as in Example 1, and after 4 hours of vacuum drying at 150 ° C., the ionic conductivity was measured according to the above method. The ionic conductivity was as follows.
0 hour: 1.25 × 10 ⁻³ S / cm
48 hours: 9.88 × 10 ⁻⁴ S / cm
120 hours: 8.28 × 10 ⁻⁴ S / cm
It was found that glass ceramics are slow to deteriorate in isobutyronitrile.

(3) Mixing with Binder When 0.62 g of the same PEO polymer as in Example 1 was mixed with the slurry immediately after the MM treatment, it was confirmed that the slurry was dissolved in the slurry. Moreover, when 0.41 g of PVDF-HFP was mixed with the slurry immediately after the MM treatment, it was confirmed that the slurry was dissolved in the slurry.

Example 3
(1) Slurry of solid electrolyte 4 g of the glass of Production Example 2 was transferred to a 45 ml mill pot containing 20 Zr balls having a diameter of 10 mm in advance, and 16 g of isobutyronitrile (moisture content of 50 ppm or less) subjected to N ₂ bubbling treatment for 24 hours. In addition, it was sealed (solid content concentration 20 wt%). This was mechanically milled at 370 rpm for 120 minutes to pulverize the glass to obtain a slurry containing the pulverized glass.

(2) Storage of the slurry The slurry was stored in the same manner as in Example 1, and after vacuum drying at 150 ° C. for 4 hours, the ionic conductivity was measured according to the above method. The ionic conductivity was as follows.
0 hour: 1.40 × 10 ⁻⁴ S / cm
70 hours: 3.24 × 10 ⁻⁴ S / cm
166 hours: 2.26 × 10 ⁻⁴ S / cm
Glass was found to be slow to degrade in isobutyronitrile.

(3) Mixing with binder When 0.62 g of PEO polymer was mixed with the slurry immediately after the MM treatment, it was confirmed that the slurry was dissolved in the slurry. Moreover, when 0.41 g of PVDF-HFP was mixed with the slurry immediately after the MM treatment, it was confirmed that the slurry was dissolved in the slurry.

Comparative Example 1
As in Production Example 1, a 70Li ₂ S-30P ₂ S ₅ sulfide-based solid electrolyte (glass ceramics) was produced, and 30 g of this solid electrolyte was sealed in a glass bottle. This operation was performed in a glove box (dew point −90 ° C., oxygen concentration 0.1 ppm).
This state was stored for 240 hours, and the ionic conductivity was measured and evaluated. The ionic conductivity was 1.32 × 10 ⁻³ S / cm.
Comparative Example 1 shows that the electrolyte can be prevented from deteriorating if stored with a very low dew point. Therefore, according to the present invention, it can be seen that the deterioration of the electrolyte can be prevented in the same manner as the storage in a state where the dew point is very low.

Comparative Example 2
(1) Slurry of solid electrolyte 8 g of the glass ceramic of Production Example 1 was transferred to a 45 ml mill pot in which 20 Zr balls having a diameter of 10 mm were previously placed and subjected to N ₂ bubbling treatment for 24 hours (product name: manufactured by Kishida Chemical Co., Ltd.). Special grade) (water content 50 ppm or less) 12 g was added and sealed (solid content concentration 40 wt%). This was mechanically milled at 370 rpm for 120 minutes to pulverize the glass ceramics to obtain a slurry containing the pulverized glass ceramics.
The slurry was air-dried and then vacuum-dried at 150 ° C. for 2 hours with a tube heater, and the particle size was measured. The average particle size was 10 μm. The method for measuring the particle size is the same as described above.

(2) Storage of slurry The slurry was stored in the same manner as in Example 1, and the ionic conductivity was measured. The ionic conductivity was as follows.
0 hour: 8.76 × 10 ⁻⁴ S / cm
48 hours: 4.19 × 10 ⁻⁴ S / cm
120 hours: 2.72 × 10 ⁻⁴ S / cm
It has been found that glass ceramics are rapidly degraded in diethyl carbonate.

(3) Mixing with binder When 0.62 g of PEO polymer was mixed with the slurry immediately after the MM treatment, it was confirmed that the slurry was dissolved in the slurry. However, when 0.41 g of PVDF-HFP was mixed with the slurry immediately after the MM treatment, it was not dissolved in the slurry.

Comparative Example 3
10 g of the glass ceramic of Production Example 1 was transferred to a 45 ml mill pot in which 20 Zr balls having a diameter of 10 mm were previously placed, and 15 g of propionitrile (CH ₃ CH ₂ CN) (moisture content of 50 ppm or less) subjected to N ₂ bubbling treatment for 24 hours. In addition, it was sealed (solid content concentration 40 wt%). This was mechanically milled at 370 rpm for 60 minutes to pulverize the glass ceramics and obtain a slurry containing the pulverized glass ceramics.
However, the glass ceramics expanded and did not become a slurry.

Comparative Example 4
(1) Slurry of solid electrolyte 2 g of the glass of Production Example 2 was subjected to N ₂ bubbling treatment for 24 hours, and 6.4 g of diethyl carbonate (manufactured by Kishida Chemical Co., Ltd., product name: special grade) (water content of 50 ppm or less) was added and sealed. (Solid content concentration 24 wt%). This was stirred for 3 hours to obtain a slurry containing glass.

(2) Storage of slurry The slurry was stored in the same manner as in Example 1, and the ionic conductivity was measured. The ionic conductivity was as follows.
0 hour: 2.49 × 10 ⁻⁵ S / cm
It has been found that the glass is rapidly degraded in diethyl carbonate.

(3) Mixing with binder When 0.26 g of a PEO polymer was mixed with the slurry immediately after the MM treatment, it was confirmed that it was dissolved in the slurry. However, when 0.17 g of PVDF-HFP was mixed with the slurry immediately after the MM treatment, it did not dissolve in the slurry.

  The composition of this invention can be used for the member of a lithium ion battery.

Claims (6)

Lithium ion conductive solid electrolyte containing lithium and sulfur,
A nitrile compound represented by formula (1), and a binder,
The nitrile compound is liquid at a temperature of 25 ° C. and a pressure of 101325 Pa.
A composition satisfying the formulas (I) and (II).
R-CN (1)
(In Formula (1), R is a linear or branched hydrocarbon group having 3 to 40 carbon atoms, or a group having a cyclic structure having 3 to 10 carbon atoms, and carbonization having 1 to 20 carbon atoms. A hydrogen group and / or a group having a cyclic structure having 3 to 10 carbon atoms may be included.)
0.05 ≦ (Y + Z) / (X + Y + Z) ≦ 0.75 (I)
Z / (Y + Z) ≦ 0.5 (II)
(In formulas (I) and (II), X represents the weight of the nitrile compound, Y represents the weight of the lithium ion conductive solid electrolyte, and Z represents the weight of the binder.)   The composition according to claim 1, wherein the lithium ion conductive solid electrolyte is pulverized electrolyte particles.   The composition according to claim 1 or 2, wherein the nitrile compound has a water content of 50 ppm or less.   The composition in any one of Claims 1-3 containing an active material. A method for storing a lithium ion conductive solid electrolyte, comprising storing a lithium ion conductive solid electrolyte containing lithium and sulfur in a nitrile compound represented by formula (1) that is liquid at a temperature of 25 ° C. and a pressure of 101325 Pa.
R-CN (1)
(R in Formula (1) is a linear or branched hydrocarbon group having 3 to 40 carbon atoms, or a group having a cyclic structure having 3 to 10 carbon atoms, and having 1 to 20 carbon atoms. A hydrogen group and / or a group having a cyclic structure having 3 to 10 carbon atoms may be included.) A method for storing a lithium ion conductive solid electrolyte and a binder, wherein the lithium ion conductive solid electrolyte and binder containing lithium and sulfur are stored in a nitrile compound represented by formula (1) that is liquid at a temperature of 25 ° C. and a pressure of 101325 Pa. .
R-CN (1)
(R in Formula (1) is a linear or branched hydrocarbon group having 3 to 40 carbon atoms, or a group having a cyclic structure having 3 to 10 carbon atoms, and having 1 to 20 carbon atoms. A hydrogen group and / or a group having a cyclic structure having 3 to 10 carbon atoms may be included.)