JP2013222530A - All solid state battery and method for charging/discharging all solid state battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an all solid state battery improved in cycle characteristics.SOLUTION: An all solid state battery includes a negative electrode layer and an electrolyte layer containing an inorganic solid electrolyte. In the all solid state battery, a retention rate of a discharge capacity after 100 cycles is 50% or more, under a charge/discharge cycle condition where constant current (CC) charging till 2.65 V at 0.2 C is performed, constant voltage (CV) charging till a current of 0.01 C at a voltage of 2.65 V is performed, and constant current (CC) charging till 0.6 V at 0.2 C is performed.

Description

  The present invention relates to an all-solid battery and an all-solid battery charge / discharge method.

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.
However, a lithium secondary battery using an organic electrolyte has a risk of leakage, ignition and explosion, and a battery with higher safety is desired.

  As a battery for solving the safety problem, an all-solid battery using a solid electrolyte instead of an organic electrolyte has been proposed. The all-solid-state battery has a feature that electrolyte leakage and ignition hardly occur, but has a disadvantage that cycle characteristics are poor.

  An object of the present invention is to provide an all-solid battery having improved cycle characteristics.

According to the present invention, the following all solid state battery and the like are provided.
1. A negative electrode layer;
An electrolyte layer containing an inorganic solid electrolyte;
An all solid state battery comprising:
At 0.2C, constant current (CC) charge up to 2.65V, and at constant voltage (CV) charge until current reaches 0.01C at a voltage of 2.65V. An all-solid-state battery having a discharge capacity maintenance rate of 50% or more after 100 cycles under conditions of a charge / discharge cycle in which current (CC) discharge is performed.
2. 2. The all solid state battery according to 1, wherein the negative electrode layer includes a negative electrode active material and an inorganic solid electrolyte.
3. 3. The all solid state battery according to 2, wherein the negative electrode active material includes one or more metals or alloys selected from silicon, tin, carbon, magnesium, aluminum, and gallium.
4). 4. The all solid state battery according to 2 or 3, wherein the negative electrode active material has an average particle size of 0.01 μm to 100 μm, and the inorganic solid electrolyte has an average particle size of 0.01 μm to 100 μm.
5. The all-solid-state battery in any one of 1-4 whose said inorganic solid electrolyte is the glass which satisfy | fills the composition shown to following formula (1), or the glass ceramics which satisfy | fill the composition shown to following formula (1).
Li _{a Mb} P _c S _d (1)
(In the formula, M represents an element selected from B, Zn, Si, Cu, Ga and Ge. Ad represents the composition ratio of each element, and a: b: c: d represents 1 to 12: 0-0.2: 1: 2-9 are satisfied.)
6). Li ion insertion capacity [mAh / g] into the negative electrode active material, which is performed for the first time after battery manufacture, is not less than (20% of theoretical capacity [mAh / g] of the negative electrode active material),
In the Li ion desorption from the negative electrode active material following the first Li ion insertion performed for the first time, the charging of the all-solid-state battery that ends discharge by leaving lithium in a capacity corresponding to 0.03X or more and 50X or less in the negative electrode active material. Discharge method.
(X is the insertion of Li ions into the negative electrode active material for the first time after half-cell production, and at 0.5 mA / cm ² , Li ions are inserted until the negative electrode active material potential becomes 0.01 V vs. Li / Li ⁺ , then 0.01Vvs.Li/Li ⁺ a, by inserting Li ions until 0.127mA / cm ^2, was desorbed Li ions at 0.5 mA / cm ² until the potential 1.52Vvs.Li/Li ⁺ In this case, the Li capacity remaining in the negative electrode active material.
However, the half cell that determines X includes a structure in which a negative electrode layer and an electrolyte layer are laminated, and the negative electrode active material included in the negative electrode layer is the same as the negative electrode active material included in the negative electrode layer of the all-solid battery, The amount per layer unit area is the same, and the inorganic solid electrolyte included in the electrolyte layer is the same as the inorganic solid electrolyte included in the electrolyte layer of the all-solid battery, and the amount per unit area of the electrolyte layer is the same. . )

  According to the present invention, an all-solid battery with improved cycle characteristics can be provided.

It is a figure which shows the relationship between Li desorption capacity per Si weight of the half cell manufactured in Example 1, and the number of Li desorption insertion cycles.

[All-solid battery]
The all solid state battery of the present invention is an all solid state battery comprising a negative electrode layer and an electrolyte layer containing an inorganic solid electrolyte, and is charged at a constant current (CC) up to 2.65V at 0.2C and at a voltage of 2.65V. Maintaining discharge capacity after 100 cycles under constant charge (CV) charge until current reaches 0.01C and constant current (CC) discharge at 0.2C to 0.6V The rate is 50% or more.

The discharge capacity maintenance rate is 0.2 C, constant current (CC) charge up to 2.65 V, and constant voltage (CV) charge until the current reaches 0.01 C at a voltage of 2.65 V. Then, under the condition of the charge / discharge cycle in which the constant current (CC) discharge is performed up to 0.6V, the first time “0.2C, the constant current (CC) is charged up to 2.65V and the voltage is 2.65V. The discharge capacity (hereinafter referred to as “M ₁ ” as appropriate) was charged at a constant voltage (CV) until the current reached 0.01 C, and was discharged at a constant current (CC) to 0.6 V at 0.2 C. .) And “constant current (CC) charge up to 2.65V at 0.2C, constant voltage (CV) charge until the current reaches 0.01C at a voltage of 2.65V, 0.6V up to a constant current (CC) 100 th discharge capacity in the case of performing 100 times the discharge "(hereinafter, appropriately referred to as" M ₀₀ "called.) Is the ratio of the.
That is, “100 × M ₁₀₀ / M ₁ ” becomes the discharge capacity maintenance rate after 100 cycles.
The discharge capacity maintenance rate after 100 cycles of the all solid state battery of the present invention is preferably 50% or more, more preferably 70% or more.

The all solid state battery of the present invention is specifically an all solid state battery comprising a negative electrode layer, an electrolyte layer containing an inorganic solid electrolyte, and a positive electrode layer.
Hereafter, each structural member of the all-solid-state battery of this invention is demonstrated.

[Negative electrode layer]
The negative electrode layer is preferably a layer containing a negative electrode active material and an inorganic solid electrolyte, for example, a layer containing negative electrode active material particles and inorganic solid electrolyte particles.
(1) Negative electrode active material A negative electrode active material is a negative electrode active material whose theoretical capacity is 800 mAh / g or more, for example. When the theoretical capacity is 800 mAh / g or more, a lithium ion battery having a large energy density can be obtained.
The theoretical capacity is preferably 1500 mAh / g or more, and a lithium battery having a higher energy density can be obtained when the theoretical capacity is 1500 mAh / g or more.
Here, the negative electrode active material may be particles or may not be in the form of particles.
In addition, when the negative electrode active material is negative electrode active material particles, the surface thereof may be coated.

When the negative electrode active material is negative electrode active material particles, the average particle size of the negative electrode active material particles is preferably 0.01 μm or more and 100 μm or less, more preferably 0.05 μm or more and 50 μm or less.
By making the average particle diameter of the negative electrode active material particles 100 μm or less, the number of contact points with the inorganic solid electrolyte particles and the like in the negative electrode layer can be increased, and a sufficient lithium ion conduction path and electron conduction path can be formed. Li insertion / extraction capacity can be increased.
Further, when a composite material including negative electrode active material particles and inorganic solid electrolyte particles is used as the material of the negative electrode layer, the average particle size of the negative electrode active material particles is set to 100 μm or less in the negative electrode layer immediately after production. The number of contact points with the inorganic solid electrolyte particles and the like in the layer can be increased, a sufficient lithium ion conduction path and electron conduction path can be formed, and the Li desorption capacity can be increased. It is presumed that this effect is maintained even when the negative electrode active material particles and / or the inorganic solid electrolyte particles are not in a particulate form by repeating charge and discharge.
Here, the average particle diameter of the negative electrode active material particles can be measured by, for example, observation with a scanning electron microscope, observation with a transmission electron microscope, or a laser diffraction particle size distribution measurement method.

As the negative electrode active material, either a single negative electrode active material or an alloy containing the negative electrode active material can be suitably used. Further, the metal or alloy constituting the negative electrode active material may be any metal or alloy capable of inserting and releasing lithium ions, and a known negative electrode active material in the battery field can be used, preferably silicon, tin, carbon One or more metals or alloys selected from magnesium, aluminum and gallium.
Specific examples of the negative electrode active material include simple metals such as indium, aluminum, silicon, tin, boron, phosphorus, magnesium, calcium, germanium, silver, platinum, lead, bismuth, gallium, and other elements or compounds in these metals. And an alloy containing these metals, more preferably an element containing silicon and an alloy containing silicon.
Examples of the other elements include lithium.

(2) Inorganic solid electrolyte Examples of the inorganic solid electrolyte include (i) an oxide-based solid electrolyte and (ii) a sulfide-based solid electrolyte.
The inorganic solid electrolyte may be a particle or may not take a particulate shape.

(I) Oxide-based solid electrolytes As oxide-based solid electrolytes, LiN, LISICONs; Thio-LISICONs; LiTi ₂ P ₃ O ₁₂ having a NASICON type structure, and an electrolyte obtained by crystallizing them; La _0. A crystal having a perovskite structure such as ₅₅ Li _0.35 TiO ₃ can be used.

(Ii) Sulfide-based solid electrolyte The sulfide-based solid electrolyte is a lithium ion conductive inorganic solid electrolyte that satisfies the composition represented by the following formula (1), for example.
Li _{a Mb} P _c S _d (1)
(In the formula, M represents an element selected from B, Zn, Si, Cu, Ga and Ge. Ad represents the composition ratio of each element, and a: b: c: d represents 1 to 12: 0-0.2: 1: 2-9 are satisfied.)

In the formula (1), the composition ratio of Li, M, P and S is preferably such that b is 0, more preferably b = 0 and the ratio of a, c and d (a: c: d) is a. : C: d = 1-9: 1: 3-7, more preferably b = 0 and a: c: d = 1.5-4: 1: 3.25-4.5.
The composition ratio of each element can be controlled by adjusting the blending amount of the raw material compound when producing the sulfide-based solid electrolyte as described below.

The sulfide-based solid electrolyte may be amorphous (glass) or crystallized (glass ceramic), or only a part may be crystallized.
Here, when crystallized, the ion conductivity may be higher than that of glass. In that case, it is preferable to crystallize.

The crystal structure of the crystallized sulfide-based solid electrolyte is preferably Li ₇ PS ₆ structure, Li ₄ P ₂ S ₆ structure, Li ₃ PS ₄ structure, Li ₄ SiS ₄ structure disclosed in JP-A-2002-109955, Li ₂ SiS ₃ structure, or Li ₇ P ₃ S ₁₁ structure disclosed in Japanese Patent Application Laid-Open No. 2005-228570 and WO 2007/066539, and most preferably Li ₇ P ₃ S ₁₁ structure.
The crystallized portion of the crystallized sulfide solid electrolyte only needs to have any one of these crystal structures, and may have a plurality of crystal structures. Crystallized sulfide solid electrolytes having these crystal structures can exhibit higher ionic conductivity than amorphous sulfide solid electrolytes.
For example, the Li ₇ P ₃ S ₁₁ structure has 2θ = 17.8 ± 0.3 deg, 18.2 ± 0.3 deg, 19.8 ± 0. 0 in X-ray diffraction (CuKα: λ = 1.5418４). It has diffraction peaks at 3 deg, 21.8 ± 0.3 deg, 23.8 ± 0.3 deg, 25.9 ± 0.3 deg, 29.5 ± 0.3 deg, 30.0 ± 0.3 deg.

The degree of crystallinity of the crystallized sulfide-based solid electrolyte (the degree of crystallinity of the crystal structure having higher ionic conductivity than that of the amorphous body) is preferably 50% or more, more preferably 60% or more.
When the crystallinity of the crystallized sulfide-based solid electrolyte is less than 50%, the effect of increasing the ionic conductivity by crystallization may be reduced.

The degree of crystallinity can be measured by using an NMR spectrum apparatus. Specifically, the solid ³¹ P-NMR spectrum of the crystallized sulfide-based solid electrolyte is measured, and the resonance line observed at 70-120 ppm is converted into a Gaussian curve using a nonlinear least square method. It can measure by isolate | separating and calculating | requiring the area ratio of each curve.

As raw materials used for the production of the sulfide-based solid electrolyte, Li ₂ S (lithium sulfide), P ₂ S ₃ (phosphorus trisulfide), P ₂ S ₅ (phosphorus pentasulfide), SiS ₂ (silicon sulfide), Li ₄ SiO ₄ (lithium orthosilicate), Al ₂ S ₃ (aluminum sulfide), simple phosphorus (P), simple sulfur (S), silicon (Si), GeS ₂ (germanium sulfide), B ₂ S ₃ (trisulfide) Diarsenic), Li ₃ PO ₄ (lithium phosphate), Li ₄ GeO ₄ (lithium germanate), LiBO ₂ (lithium metaborate), LiAlO ₃ (lithium aluminate), etc. can be used, and Li ₂ S (sulfurized) Lithium) and P ₂ S ₅ (phosphorus pentasulfide) are preferably used.

A method for producing a sulfide-based solid electrolyte in the case where Li ₂ S (lithium sulfide) and P ₂ S ₅ (diphosphorus pentasulfide) are used as raw materials for the sulfide-based solid electrolyte will be described.
The raw material lithium sulfide is not particularly limited. For example, industrially available ones can be used, and the methods disclosed in JP-A-7-330312, JP-A-9-283156, JP-A-2010-163356, JP-A-2011-084438 are used. Lithium sulfide that can be produced can be used.
In JP 2010-163356 A, lithium hydroxide and hydrogen sulfide are reacted at 70 ° C. to 300 ° C. in a hydrocarbon-based organic solvent to produce lithium hydrosulfide, and this reaction solution is then desulfurized. Lithium sulfide is synthesized by hydrogenation. Moreover, in the said Unexamined-Japanese-Patent No. 2011-084438, lithium hydroxide and hydrogen sulfide are made to react at 10 to 100 degreeC in a water solvent, lithium lithium sulfide is produced | generated, and this reaction liquid is then dehydrosulfurized. To synthesize lithium sulfide.

Lithium sulfide preferably has a total content of lithium salt of sulfur oxide of 0.15% by mass or less, more preferably a total content of lithium salt of sulfur oxide of 0.1% by mass or less. The lithium sulfide preferably has a lithium N-methylaminobutyrate content of 0.15% by mass or less, and more preferably a lithium N-methylaminobutyrate content of 0.1% by mass or less.
When the total content of the lithium salt of sulfur oxide is 0.15% by mass or less, the solid electrolyte obtained by the melt quenching method or the mechanical milling method can be made into a glassy electrolyte (fully amorphous). On the other hand, if the total content of the lithium salt of the sulfur oxide exceeds 0.15% by mass, the obtained electrolyte may become a crystallized product from the beginning, and since the ionic conductivity of this crystallized product is low, it is glassy. The ionic conductivity of the electrolyte may be lowered. Further, even if this crystallized product is subjected to a heat treatment, the crystallized product is not changed, and there is a possibility that a sulfide-based solid electrolyte having high ion conductivity cannot be obtained.
In addition, when the content of lithium N-methylaminobutyrate is 0.15% by mass or less, a deteriorated product of lithium N-methylaminobutyrate does not deteriorate the cycle performance of the lithium ion battery.
By using lithium sulfide with reduced impurities in this way, a high ion conductive electrolyte can be obtained.

In the method for producing lithium sulfide described in JP-A-7-330312 and JP-A-9-283156, the obtained lithium sulfide contains a lithium salt of sulfur oxide and the like, and thus it is preferably purified. On the other hand, in the method for producing lithium sulfide described in JP 2010-163356 A, the obtained lithium sulfide can be used as it is without purification because it contains a very small amount of lithium oxide lithium salt or the like.
In the case of purifying lithium sulfide, a preferable purification method includes, for example, a purification method disclosed in International Publication WO2005 / 40039, and the obtained lithium sulfide is washed at a temperature of 100 ° C. or higher using an organic solvent. To be purified.

P ₂ S ₅ (phosphorus pentasulfide) used as a raw material for the sulfide-based solid electrolyte can be used without particular limitation as long as it is industrially produced and sold diphosphorus pentasulfide.

Sulfide-based solid electrolytes (sulfide-based glass solid electrolytes) are prepared by melting and quenching a mixture of lithium sulfide and phosphorous pentasulfide, a mechanical milling method (MM method), a slurry method in which raw materials are reacted in an organic solvent, etc. It can be produced by reacting.
The mixing ratio (molar ratio) of lithium sulfide and diphosphorus pentasulfide is usually Li ₂ S: P ₂ S ₅ = 40: 60 to 90:10, preferably Li ₂ S: P ₂ S ₅ = 60: 40. to 78: a 22, particularly preferably _{Li 2 S: P 2 S 5} = 68: 32~76: a 24 (molar ratio).

In the case of producing a sulfide-based glass solid electrolyte by a melt quenching method, for example, the melt quenching method disclosed in JP-A-6-279049 or WO2005 / 119706 may be carried out.
Specifically, P ₂ S ₅ and Li ₂ S are mixed in a predetermined amount in a mortar to form a pellet, and the pellet is placed in a carbon-coated quartz tube and vacuum-sealed. Then, it is made to react at a predetermined reaction temperature, put into ice and rapidly cooled to obtain a sulfide-based glass solid electrolyte.
The reaction temperature is preferably 400 ° C to 1000 ° C, more preferably 800 ° C to 900 ° C. Moreover, reaction time becomes like this. Preferably it is 0.1 to 12 hours, More preferably, it is 1 to 12 hours.
The quenching temperature of the reaction product is usually 10 ° C. or less, preferably 0 ° C. or less, and the cooling rate is usually about 1 to 10,000 K / sec, preferably 10 to 10,000 K / sec.

When a sulfide-based glass solid electrolyte is produced by a mechanical milling method, for example, a mechanical milling method disclosed in JP-A-11-134937, JP-A-2004-348972, or JP-A-2004-34897 (hereinafter referred to as “appropriately” MM method)).
Specifically, a predetermined amount of P ₂ S ₅ and Li ₂ S are mixed in a mortar, and the mixture is reacted for a predetermined time using, for example, various ball mills, etc., thereby obtaining a sulfide-based glass solid electrolyte.
In the MM method, the reaction can be performed at room temperature, and the glass solid electrolyte can be produced at room temperature. Therefore, there is an advantage that the raw material is not thermally decomposed and a glass solid electrolyte having a charged composition can be obtained. Further, the MM method has an advantage that the glass solid electrolyte can be made into fine powder simultaneously with the production of the glass solid electrolyte.
Note that the MM method is not limited to room temperature, and as disclosed in JP 2010-30889 A, the temperature in the mill during the mechanical milling process may be adjusted. It is preferable that the raw material be 60 ° C. or higher and 160 ° C. or lower during mechanical milling.

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 described in Japanese Patent Application Laid-Open No. 2010-90003, balls of different diameters are used for balls of a ball mill. You may mix and use.
As conditions for the MM method, for example, when a planetary ball mill is used, the rotational speed may be set to several tens to several hundreds of revolutions / minute, and the treatment may be performed for 0.5 hours to 100 hours.
In addition to the above, as disclosed in JP2009-110920A and JP2009-2111950A, an organic solvent is added to a mixture of P ₂ S ₅ and Li ₂ S to form a slurry, and this slurry May be mechanically milled.

When the sulfide-based glass solid electrolyte is produced by a slurry method, for example, the slurry method disclosed in WO2004 / 093099 or WO2009 / 047977 may be carried out.
Specifically, a sulfide-based glass solid electrolyte is obtained by reacting a predetermined amount of P ₂ S ₅ particles and Li ₂ S particles in an organic solvent for a predetermined time. Moreover, a finer sulfide-based glass solid electrolyte can be obtained by further pulverizing the obtained slurry containing the solid electrolyte with a bead mill or the like.
The reaction temperature is preferably 20 ° C. or higher and 80 ° C. or lower, more preferably 20 ° C. or higher and 60 ° C. or lower. The reaction time is preferably 1 hour or longer and 16 hours or shorter, more preferably 2 hours or longer and 14 hours or shorter.

  When carrying out the slurry method, it is preferable to add an organic solvent to the raw materials lithium sulfide and diphosphorus pentasulfide to form a solution or slurry, and the raw materials (total amount) per liter of the organic solvent. Usually, 0.001 kg or more and 1 kg or less are added, preferably 0.005 kg or more and 0.5 kg or less are added, and particularly preferably 0.01 kg or more and 0.3 kg or more are added.

  The organic solvent to be added is not particularly limited, but is preferably an aprotic organic solvent, such as an aprotic organic solvent (for example, a hydrocarbon organic solvent), an aprotic polar organic compound (for example, an amide compound, a lactam). Compounds, urea compounds, organic sulfur compounds, cyclic organophosphorus compounds, etc.) can be used as a single solvent or as a mixed solvent thereof.

As the hydrocarbon organic solvent, a saturated hydrocarbon solvent, an unsaturated hydrocarbon solvent, or an aromatic hydrocarbon solvent can be used.
Examples of the saturated hydrocarbon solvent include hexane, pentane, 2-ethylhexane, heptane, decane, and cyclohexane; examples of the unsaturated hydrocarbon solvent include hexene, heptene, cyclohexene, and the like. Include toluene, xylene, decalin, 1,2,3,4-tetrahydronaphthalene and the like. Of these hydrocarbon organic solvents, toluene and xylene are particularly preferable.

When a hydrocarbon organic solvent is used in the slurry method, the hydrocarbon organic solvent is preferably dehydrated in advance, and specifically, a hydrocarbon organic solvent having a moisture content of 100 ppm by weight or less is preferable. A hydrocarbon organic solvent having a water content of 30 ppm by weight or less is particularly preferable.
In addition, you may add another solvent to a hydrocarbon type organic solvent as needed. Specific examples of other solvents that can be added include ketones such as acetone and methyl ethyl ketone; ethers such as tetrahydrofuran; alcohols such as ethanol and butanol; esters such as ethyl acetate; halogenated carbonization such as dichloromethane and chlorobenzene. Hydrogen etc. are mentioned.

  In carrying out the slurry method, the reaction disclosed in Japanese Patent Application Laid-Open No. 2010-140893 may be performed by circulating the slurry containing the raw material between the bead mill and the reaction vessel. The raw material lithium sulfide may be pulverized in advance in order to advance the reaction efficiently as disclosed in JP-A-2011-136899, in order to increase the specific surface area of the raw material lithium sulfide, You may immerse in a polar solvent (for example, methanol, diethylcarnate, acetonitrile) whose solubility parameter is 9.0 or more for a predetermined time.

  The case where the sulfide-based glass solid electrolyte is produced by the melt quenching method, the mechanical milling method, or the slurry method has been described, but the production conditions such as temperature conditions, processing time, and charge when carrying out these methods are limited to the above. However, it can be adjusted appropriately according to the equipment used.

A sulfide-based crystallized glass solid electrolyte (sulfide-based glass ceramic solid electrolyte) can be produced by heat-treating the sulfide-based glass solid electrolyte at a predetermined temperature.
A method for producing a sulfide-based solid electrolyte (glass ceramic) is disclosed in, for example, JP-A-2005-228570, WO2007 / 065539, and JP-A-2002-109955.
Although described below a method of manufacturing a sulfide-based glass ceramic solid electrolyte, a sulfide-based glass solid electrolyte used in the preparation of the sulfide-based glass ceramic solid electrolyte material in Li 2 _{S (lithium} sulfide) and P ₂ S It is not limited to the sulfide type glass solid electrolyte obtained using ₅ (diphosphorus pentasulfide).

The heat treatment temperature for producing a sulfide-based glass ceramic solid electrolyte having a Li ₇ P ₃ S ₁₁ structure is preferably 180 ° C. or higher and 330 ° C. or lower, more preferably 200 ° C. or higher and 320 ° C. or lower, and particularly preferably It is 210 degreeC or more and 310 degrees C or less.
When the heat treatment temperature is less than 180 ° C., it may be difficult to obtain a crystallized glass with a high degree of crystallinity, and when the heat treatment temperature exceeds 330 ° C., there is a possibility that a crystallized glass with a low degree of crystallinity will be produced.

The heat treatment time for producing a sulfide-based glass ceramic solid electrolyte having a Li ₇ P ₃ S ₁₁ structure is preferably 3 hours or more and 240 hours or less when the heat treatment temperature is 180 ° C. or more and 210 ° C. or less, Especially preferably, it is 4 hours or more and 230 hours or less. In the case where the heat treatment temperature is higher than 210 ° C. and 330 ° C. or lower, it is preferably 0.1 hours or longer and 240 hours or shorter, more preferably 0.2 hours or longer and 235 hours or shorter, and even more preferably 0.3 hours or shorter. It is more than time and less than 230 hours.
When the heat treatment time is less than 0.1 hour, it may be difficult to obtain a crystallized glass with a high degree of crystallinity, and when the heat treatment time is over 240 hours, a crystallized glass with a low degree of crystallinity may be generated.

The heating conditions for producing a sulfide-based glass ceramic solid electrolyte having a Li ₇ PS ₆ structure, a Li ₄ P ₂ S ₆ structure, a Li ₃ PS ₄ structure and / or a Li ₄ SiS ₄ structure are known heating conditions. For example, the heating conditions disclosed in JP-A-2002-109955 can be applied.
Incidentally, sulfide-based glass ceramic solid electrolyte having the above-mentioned _Li 4 SiS ₄ structure, it is conceivable to produce, for example, from SiS ₂ and Li ₂ S.

A sulfide-based glass-ceramic solid electrolyte having a Li ₇ P ₃ S ₁₁ structure, and a sulfide-based glass having a Li ₇ PS ₆ structure, a Li ₄ P ₂ S ₆ structure, a Li ₃ PS ₄ structure, and / or a Li ₄ SiS ₄ structure. Whichever ceramic solid electrolyte is manufactured, the heat treatment is preferably performed in an environment having a dew point of −40 ° C. or lower, more preferably in an environment having a dew point of −60 ° C. or lower.
The pressure at the time of heating may be a normal pressure or a reduced pressure. The heating atmosphere may be air or an inert atmosphere.
In addition to the above, the heat treatment may be performed in a solvent disclosed in JP 2010-186744 A.

(3) Others The negative electrode layer may be composed of only the negative electrode active material and the inorganic solid electrolyte, and may further contain a conductive additive, a binder, and the like.
The conductive auxiliary agent only needs to have conductivity, and its electronic conductivity is preferably 1 × 10 ³ S / cm or more, more preferably 1 × 10 ⁵ S / cm or more. Examples of the conductive aid include substances selected from carbon materials, metal powders and metal compounds, and mixtures thereof.
Specific examples of conductive aids are preferably carbon materials, nickel, copper, aluminum, indium, silver, cobalt, magnesium, lithium, chromium, gold, ruthenium, platinum, beryllium, iridium, molybdenum, niobium, osnium, rhodium, A substance containing at least one element selected from the group consisting of tungsten and zinc, and more preferably a carbon simple substance having a high conductivity, or a carbon material other than simple carbon; nickel, copper, silver, cobalt, magnesium, lithium, ruthenium , Gold, platinum, niobium, osnium or rhodium, simple metals, mixtures or compounds.
Specific examples of carbon materials include carbon blacks such as ketjen black, acetylene black, denka black, thermal black, and channel black; graphite, carbon fiber, activated carbon, and the like. These may be used alone or in combination of two or more. Is possible. Among these, acetylene black, denka black, and ketjen black having high electron conductivity are preferable.

The binder can improve the moldability of the battery and the bondability of the particles in the battery, thereby improving the charge / discharge capacity.
Examples of binders include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), fluorine-containing resins such as fluororubber; thermoplastic resins such as polypropylene and polyethylene; ethylene-propylene-dienemer (EPDM), sulfonated EPDM, natural Butyl rubber (NBR) or the like can be used alone or as a mixture of two or more. In addition, an aqueous dispersion of cellulose or styrene butadiene rubber (SBR), which is an aqueous binder, can also be used.

The mixing ratio (weight ratio) of the negative electrode active material and the inorganic solid electrolyte contained in the negative electrode layer is preferably negative electrode active material: inorganic solid electrolyte = 95: 5 to 30:70, more preferably negative electrode active material: inorganic solid electrolyte. = 85: 15-40: 60.
When the ratio of the negative electrode active material to the inorganic solid electrolyte is 95% by weight or less, the lithium ion conduction path in the negative electrode layer is increased, the reaction sites are increased, and the Li desorption capacity can be further increased. Moreover, when the ratio of the negative electrode active material with respect to an inorganic solid electrolyte is 30 weight% or more, the amount of negative electrodes in a negative electrode layer increases, and Li insertion capacity can be increased more.

[Electrolyte layer]
The solid electrolyte layer is a layer containing an inorganic solid electrolyte, and may further contain a binder or the like, and the binder is as described above.
The solid electrolyte contained in the negative electrode layer and the solid electrolyte contained in the solid electrolyte layer may be the same or different.
Therefore, the description about the matter mentioned above about a solid electrolyte and a binder is abbreviate | omitted.

As described above, the shape of the solid electrolyte that is a raw material of the solid electrolyte layer may be either a particle shape or a sheet shape.
If it is a solid electrolyte particle, when forming a solid electrolyte layer, it can form by apply | coating the slurry containing a sulfide type solid electrolyte, for example, and can form simply. Moreover, if it is a solid electrolyte particle, an electrolyte layer can also be manufactured using an electrostatic method.

When the solid electrolyte layer is formed of solid electrolyte particles, the solid electrolyte particles of the solid electrolyte layer are preferably fused together. The fusion means that a part of the solid electrolyte particles is dissolved and the dissolved part is integrated with other solid electrolyte particles.
Further, the solid electrolyte layer may be a solid electrolyte plate, and the plate solid electrolyte layer is formed by dissolving a part or all of the solid electrolyte particles and bonding them together to form a plate. Including the case.

[Positive electrode layer]
The positive electrode layer is formed of a positive electrode mixture made of a positive electrode active material and a solid electrolyte. The positive electrode layer may further contain a conductive additive and / or a binder.
The solid electrolyte contained in the positive electrode layer can be the same as the solid electrolyte of the negative electrode layer, and the conductive aid and binder of the positive electrode layer can be the same as the conductive aid and binder of the negative electrode layer. . Therefore, description about a solid electrolyte, a conductive support agent, and a binder is abbreviate | omitted.
When the positive electrode layer includes a solid electrolyte, the solid electrolyte may be the same as or different from the solid electrolyte included in the negative electrode layer and / or the solid electrolyte included in the electrolyte layer.

The positive electrode active material is a material capable of inserting and removing lithium ions, and those known as a positive electrode active material in the battery field can be used.
Specific examples of the positive electrode active material include V ₂ O ₅ , LiCoO ₂ , LiNiO ₂ , LiMnO ₂ , LiMn ₂ O ₄ , Li (Ni _a Co _b Mn _c ) O ₂ (where 0 <a <1,0 <B <1, 0 <c <1, a + b + c = 1), LiNi _1-Y Co _{Y 2} O ₂ , LiCo _1-Y Mn _{Y 2} O ₂ , LiNi _1-Y Mn _{Y 2} O ₂ (where 0 ≦ Y < _{1), Li (Ni a Co} b Mn c) O 4 (0 <a <2,0 <b <2,0 <c <2, a + b + c = 2), LiMn 2-Z Ni Z O 4, LiMn 2- _Z CoZO ₄ (where 0 <Z <2), LiCoPO ₄ , LiFePO ₄ , Li _x CoO ₂ , Li _x NiO ₂ , Li _x Mn ₂ O ₄ , Li _x FePO ₄ , Li _x CoPO ₄ , Li _x Mn _{1 / 3} Ni _1/3 Co _1/3 O ₂ , Li _x Mn _1.5 Ni _0.5 O ₂ (X is 0.1 to 0.9); titanium sulfide (TiS ₂ ), molybdenum sulfide (MoS ₂ ), iron sulfide (FeS, FeS ₂ ), sulfide copper (CuS), nickel sulfide _(Ni 3 _{S 2)} sulfide positive electrode active material such (preferably _TiS 2); bismuth oxide _{(Bi 2 O} 3), lead-acid bismuth _{(Bi 2 Pb 2 O 5)} , oxide Oxide-based positive electrode active materials (preferably cobalt acid) such as copper (CuO), vanadium oxide (V ₆ O ₁₃ ), lithium cobaltate (LiCoO ₂ ), lithium nickelate (LiNiO ₂ ), lithium manganate (LiMnO ₂ ) Lithium) and the like.
These positive electrode active materials can be used singly or as a mixture of two or more.

（式（Ａ）〜（Ｃ）において、Ｘはそれぞれ置換基であり、ｎ及びｍはそれぞれ独立に１〜２の整数であり、ｐ及びｑはそれぞれ独立に１〜４の整数である。
式（Ｄ）において、Ｚはそれぞれ−Ｓ−又は−ＮＨ−であり、ｎは繰返数２〜３００の整数である。）

（式中、ｎ、ｍは、それぞれ１以上の整数である。） In addition to the above, niobium selenide (NbSe ₃ ), organic disulfide compounds shown below, carbon sulfide compounds shown below, sulfur, lithium sulfide, indium metal, and the like can be used as the positive electrode active material.

(In Formulas (A) to (C), X is a substituent, n and m are each independently an integer of 1 to 2, and p and q are each independently an integer of 1 to 4.
In formula (D), Z is -S- or -NH-, respectively, and n is an integer of 2 to 300 repetitions. )

(In the formula, n and m are each an integer of 1 or more.)

[Current collector]
As the current collector, a known current collector can be used.
The current collector is a layer in which a layer made of a metal that reacts with a sulfide-based solid electrolyte, such as Au, Pt, Al, or Cu, is further coated with Au, conductive carbon, or the like.

Regarding the thickness of each layer of the all solid state battery of the present invention, the thickness of the positive electrode layer is preferably 0.01 mm or more and 10 mm or less, and the thickness of the solid electrolyte layer is preferably 0.001 mm or more and 1 mm or less. The thickness of the layer is preferably 0.01 mm or more and 10 mm or less.
When the all-solid-state lithium ion battery of this invention contains a collector, the thickness of the said collector is although it does not specifically limit, For example, they are 5 nm-10 mm, Preferably they are 30 nm-2 mm.
The all solid lithium ion battery of the present invention can be manufactured by a known method, for example, by a coating method or an electrostatic method (an electrostatic spray method, an electrostatic screen method, etc.).

[Charging / discharging method of all solid state battery]
In the charge / discharge method of the present invention, the Li ion insertion capacity [mAh / g] into the negative electrode active material, which is performed for the first time after the battery is manufactured, is equal to or greater than (20% of the theoretical capacity [mAh / g] of the negative electrode active material). In Li ion desorption from the negative electrode active material following Li ion insertion that is performed for the first time after the manufacture, the lithium having a capacity corresponding to 0.03X or more and 50X or less is left in the negative electrode active material, and the discharge is terminated.
X is 0.5 mA / cm ² and the negative electrode active material potential is 0.01 Vvs. In Li ion insertion into the negative electrode active material that is performed for the first time after the half cell is manufactured. Li ions were inserted until Li / Li ⁺ and then 0.01 Vvs. Li / Li ⁺ is, by inserting Li ions until 0.127mA / cm ^2, the potential 1.52Vvs at 0.5 mA / cm ^2. This is the Li capacity remaining in the negative electrode active material when Li ions are desorbed to Li / Li ⁺ .

For all solid state batteries, the cycle characteristics can be improved by carrying out the charge / discharge method of the present invention. For example, the discharge capacity after 100 cycles under specific charge / discharge cycle conditions as in the all solid state battery of the present invention. The maintenance rate can be 50% or more.
When the amount of lithium inserted into the negative electrode active material particles is not sufficient in the initial charging of the battery immediately after production, the negative electrode active material particles hardly expand, and between the negative electrode active material particles and between the negative electrode active material particles and inorganic The contact point (contact surface) between the solid electrolyte particles is not sufficiently established. On the other hand, when the amount of lithium inserted into the negative electrode active material particles is sufficient, the contact points between the negative electrode active material particles and between the negative electrode active material particles and the solid electrolyte particles increase due to sufficient expansion of the negative electrode active material particles. It is estimated that the battery performance is improved by increasing the contact area. In addition, when the amount of lithium inserted into the negative electrode active material particles is sufficient, the solid electrolyte particles and the negative electrode active material particles in the negative electrode are pressed against each other due to expansion, creating voids in the negative electrode and forming a dense negative electrode. It is presumed that the contact point is increased by the effect, and the contact area is increased.
When the amount of lithium inserted into the negative electrode active material particles is sufficient, by pressing the solid electrolyte particles or negative electrode active material particles in the negative electrode, the negative electrode active material particles and the solid electrolyte particles or other negative electrode active material particles It is estimated that it is easy to maintain the contact state, and it is easy to maintain the contact state between the negative electrode active material particles and the solid electrolyte particles or other negative electrode active material particles even if lithium is desorbed from the negative electrode active material particles to a certain amount. Presumed.
When the amount of lithium inserted into the negative electrode active material particles is insufficient, the contact state between the negative electrode active material and the inorganic solid electrolyte and the contact state between the negative electrode active materials cannot be maintained, and the contact between the negative electrode active material and the inorganic solid electrolyte is not maintained. Since the lithium ion conduction path and the electron conduction path between the negative electrode active material disappear, the Li insertion / desorption capacity into the negative electrode active material also decreases. When the charge / discharge cycle is performed in such an environment, the cycle characteristics are extremely low.
In addition, when the amount of lithium desorption from the negative electrode active material during the first discharge is increased in a state where the binding has not been sufficiently established, the volumetric shrinkage of the negative electrode active material is large, and therefore, between the particles including the negative electrode active material and the negative electrode Peeling tends to occur between the particles containing the active material and the inorganic solid electrolyte particles. As a result, the lithium ion conduction path between the negative electrode active material and the inorganic solid electrolyte and the electron conduction path between the negative electrode active material disappear, and the Li insertion / desorption capacity into the negative electrode active material also decreases.
The “irreversible capacity” is the first charge after the manufacture of the same all-solid-state battery to be charged / discharged, and remains at the negative electrode when the maximum charge is performed and the maximum discharge is performed by the subsequent discharge. Refers to the capacity of lithium.

In the charging / discharging method of the present invention, when the Li ion insertion capacity into the negative electrode active material, which is performed for the first time after battery manufacture, is less than (20% of the theoretical capacity [mAh / g] of the negative electrode active material), particles containing the negative electrode active material The expansion amount is small, the contact state between the particles is insufficient, the particles are easily separated, and the effects of the invention are hardly obtained.
Further, in the charging method of the present invention, when the remaining capacity in the negative electrode active material of lithium after Li ion desorption from the negative electrode active material following the first Li ion insertion after the battery production is less than 0.03X, After the discharge in the discharge cycle, the contact state between the particles becomes insufficient, the particles are easily separated, and the effects of the invention are hardly obtained. Similarly, when the remaining capacity in the negative electrode active material of lithium exceeds 50X, there is a possibility that sufficient capacity cannot be obtained during the charge / discharge cycle.

In the charging / discharging method of the present invention, the Li ion insertion capacity into the negative electrode active material preferably performed for the first time after the production of the battery is equal to or greater than 30% of the theoretical capacity [mAh / g] of the negative electrode active material. In Li ion desorption from the negative electrode active material following the Li ion insertion to be performed, lithium having a capacity corresponding to 0.1X or more and 20X or less is left in the negative electrode active material, and the discharge is terminated.
In the charging / discharging method of the present invention, the Li ion insertion capacity into the negative electrode active material, which is preferably performed for the first time after the battery is manufactured, is 40% or more of the theoretical capacity [mAh / g] of the negative electrode active material. In Li ion desorption from the negative electrode active material following Li ion insertion performed for the first time, lithium having a capacity corresponding to 0.2X or more and 7X or less is left in the negative electrode active material, and the discharge is terminated.

In the charging / discharging method of the present invention, the Li ion insertion capacity into the negative electrode active material that is performed for the first time after manufacturing the battery is, for example, 20% or more of the theoretical capacity [mAh / g] of the negative electrode active material). Si having a theoretical capacity of 4200 mAh / g is used as the material, and the Li ion insertion (charging) reaction is terminated at 840 mAh / g or more, which is 20% of the Si theoretical capacity, when Li ions are inserted (charged) into the negative electrode active material. As described above, program control may be performed, and a circuit capable of similar control may be used. Also, empirically, program control may be performed such that the Li ion insertion reaction (charging) is terminated at the potential (voltage) or current value when the current is 840 mAh / g or more, and a circuit capable of similar control is used. May be.
Further, in the case where Sn (theoretical capacity 990 mAh / g) is used as the negative electrode active material instead of Si, it can be carried out in the same manner as in the case of Si.
In addition, in Li ion desorption from the negative electrode active material following Li ion insertion that is performed for the first time after the manufacture of the battery, a lithium having a capacity corresponding to 0.03X or more and 50X or less is left in the negative electrode active material to complete the discharge. Measures the value of X in advance, and performs program control so that it is 0.03X or more and 50X or less at the time of Li ion desorption (discharge) from the negative electrode active material following Li ion insertion that is performed for the first time after battery manufacture. Alternatively, a circuit capable of similar control may be used. In addition, a program control may be performed so that the Li ion insertion reaction (charging) is terminated by an electric potential (voltage) or current value when 0.03X or more and 50X or less is obtained empirically. May be used.
The remaining Li ion capacity corresponds to a value obtained by subtracting the subsequent Li ion desorption capacity from the Li ion insertion capacity into the negative electrode active material.

X is 0.5 mA / cm ² and the negative electrode active material potential is 0.01 Vvs. In Li ion insertion into the negative electrode active material that is performed for the first time after the half cell is manufactured. Li ions were inserted until Li / Li ⁺ and then 0.01 Vvs. Li / Li ⁺ is, by inserting Li ions until 0.127mA / cm ^2, the potential 1.52Vvs at 0.5 mA / cm ^2. This is the Li capacity remaining in the negative electrode active material when Li ions are desorbed to Li / Li ⁺ .
Here, in the half cell for measuring X, the electrolyte layer is the same as the electrolyte layer of the all-solid battery that performs charge / discharge, and the working electrode is the same as the negative electrode layer of the all-solid battery (full cell) that performs charge / discharge. . “Same” means that for the electrolyte layer, the inorganic solid electrolyte itself and its basis weight (solid electrolytic mass per unit area) are the same, and for the negative electrode layer, the negative electrode mixture itself and its basis weight (unit area) It means that the negative electrode composite material amount is the same.
In addition, the pressure applied when pressure-molding the electrolyte layer and the negative electrode mixture layer is the same for both the half-cell and the all-solid-state battery (full cell), and the pressure applied to the cell at the start of electrochemical measurement (charge / discharge evaluation) Are the same for both half-cells and all-solid-state batteries (full cells).

[Production of solid electrolyte]
Production Example Production and purification of lithium sulfide were carried out in the same manner as in the examples of International Publication WO2005 / 040039A1. Specifically, it is as follows.
(1) Production of lithium sulfide A 10-liter autoclave equipped with a stirring blade was charged with 3326.4 g (33.6 mol) of N-methyl-2-pyrrolidone (NMP) and 287.4 g (12 mol) of lithium hydroxide at 300 rpm. The temperature was raised to 130 ° C. After the temperature rise, hydrogen sulfide was blown into the liquid for 2 hours at a supply rate of 3 liters / minute.
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. The impurity content in the obtained lithium sulfide was measured.
Incidentally, lithium sulfite _(Li 2 _SO 3), the content of each sulfur oxide lithium sulfate _(Li 2 SO ₄₎ and lithium thiosulfate _{(Li 2 S 2 O 3)} , and N- methylamino acid lithium (LMAB) Was quantified by ion chromatography. As a result, the total content of sulfur oxides was 0.13% by mass, and LMAB was 0.07% by mass.

(3) Production of solid electrolyte The solid electrolyte was obtained by the following method. High purity _Li 2 _{S0.6508g (0.01417mol)} prepared according to the method described in International Patent Publication WO2005 / _40039, P 2 _{S 5} were mixed well (Aldrich) 1.3492g (0.00607mol), The mixed powder was put into an alumina pot and completely sealed. This pot was attached to a planetary ball mill. First, milling was performed at a low speed (85 rpm) for several minutes in order to sufficiently mix the starting materials. Thereafter, the rotational speed was gradually increased to 370 rpm, and mechanical milling was performed for 20 hours.
It was confirmed by X-ray measurement that the obtained powder was vitrified. Next, this powder was heat-treated at 300 ° C. for 2 hours to obtain a solid electrolyte.
The ionic conductivity was measured by an AC impedance method (measurement frequency: 100 Hz to 15 MHz) and found to be 1.0 × 10 ⁻³ S / cm at room temperature.

Example 1
[Production and Evaluation of Half Cell Using Negative Electrode Compound]
(1) Production of negative electrode composite sheet 8.15 g of inorganic solid electrolyte powder, which is the solid electrolyte glass prepared in the production example, and Si powder having an average diameter of 5 μm (manufactured by High Purity Chemical Laboratory, purity 99.9%) 49 g was lightly mixed, and 11.5 g of isobutyronitrile (manufactured by Kishida Chemical) was added to the mixture. Furthermore, as a binder, it was dissolved in isobutyronitrile (manufactured by Kishida Chemical Co., Ltd.) so as to be 10 wt% of polyvinylidene fluoride-hexafluoropropylene copolymer (PVdF-HFP) (manufactured by arkema, KYNER (registered trademark)) 3.59 g of solution was added.
Twenty zirconia balls having a diameter of 10 mm were added to the mixture, the alumina pot was completely sealed, and the pot was attached to a planetary ball mill. A slurry was obtained by performing mechanical milling at 370 rpm for 2 hours.

Apply a conductive primer (made by Nippon Graphite, product name: Bunny Height) on aluminum foil (Toyo Aluminum, 1N-30-H18, thickness 0.03 mm) to a thickness of 0.01 mm, and fully Dried. On this electroconductive primer layer, the slurry prepared above was apply | coated, and after application | coating, it vacuum-dried at 150 degreeC for 3 hours, and obtained the negative mix sheet.
The amount of slurry applied was adjusted so that the solid content after removal of the solvent (corresponding to the weight of the negative electrode mixture) was 5.51 mg / cm ² per unit area.

(2) Production of half cell using negative electrode composite sheet 60 mg of inorganic solid electrolyte powder, which is the solid electrolyte glass prepared in the production example, was put into a ceramic cylinder having a diameter of 10 mm and subjected to pressure molding to form an electrolyte layer (electrolyte sheet) Inorganic solid electrolyte powder basis weight: 76.4 mg / cm ² ).
Next, the negative electrode composite sheet prepared in (1) (amount of negative electrode active material: 2.94 mg, basis weight of negative electrode mixture: 5.51 mg / cm ² ) was punched out into a circle using a punch with a diameter of 10 mm. The negative electrode composite material layer side of the punched sheet was pressure-molded so as to be in contact with the electrolyte layer to obtain a working electrode. From the opposite side of the working electrode, LiIn alloy foil was bonded and pressure-molded as a reference electrode and a counter electrode. Finally, the periphery of the cell was screwed at four positions every 90 degrees to pressurize in the stacking direction. In this way, a bipolar half cell having a three-layer structure was produced.
When the atomic ratio Li / In is 0.8 or less, the LiIn alloy can be used as a reference electrode because the Li desorption reaction potential is kept constant (0.62 V vs. Li / Li ⁺ ). Is possible.

(3) Evaluation of half cell using negative electrode composite material The prepared half cell was 0.5 mA / cm ² and the potential was 0.01 Vvs. Until Li / Li ⁺ , then 0.01 V vs. Li / Li ⁺ is, by inserting Li ions until 0.127mA / cm ^2, the potential 1.52Vvs at 0.5 mA / cm ^2. Li ions were desorbed to Li / Li ⁺ . At this time, the amount of Li ion insertion into the negative electrode active material performed for the first time after fabrication was 86.5% (3635 mAh / g) of the theoretical capacity of Si (4200 mAh / g).
Further, the Li capacity (687 mAh / g) remaining in Si after Li ion desorption from the negative electrode active material following Li ion insertion performed for the first time after battery production was defined as X.
The “Li ion insertion capacity” means the capacity of Li ions inserted into Si (negative electrode active material) contained in the negative electrode of the half cell. “Li capacity remaining in Si” means the capacity of Li ions remaining in Si (negative electrode active material) contained in the negative electrode of the half cell.

About the obtained half cell, cycle characteristic evaluation was performed as follows.
About 1.02 mA / cm ² for a half cell, 0.01 Vvs. Li insertion was performed at a constant current (CC) up to Li / Li ⁺ , and Li insertion was performed at a constant voltage (CV) until the current reached 0.127 mA / cm ² at that voltage. Li insertion was terminated when it reached 30.3% of the theoretical capacity of the active material (Si) during Li insertion (capacity per Si weight was 1271 mAh / g). Thereafter, at 1.02 mA / cm ² , 0.72 Vvs. Li desorption was performed at a constant current (CC) up to Li / Li ⁺ . The Li desorption cycle was repeated under these conditions, and the Li desorption capacity for each cycle was measured.
FIG. 1 shows the relationship between the Li desorption capacity per Si weight and the number of Li desorption insertion cycles.

  From FIG. 1, the Li ion insertion capacity into the negative electrode active material that is performed for the first time after manufacturing the battery is equal to or greater than (20% of the theoretical capacity [mAh / g]) of the negative electrode active material. In Example 1, in which Li ion desorption from the negative electrode active material left lithium in a capacity corresponding to 0.03X or more and 50X or less in the negative electrode active material to terminate the discharge, the discharge exceeded 200 cycles. It can be seen that the Li desorption capacity keeps almost constant.

Example 2
[Manufacture and evaluation of all-solid-state batteries]
(4) Preparation of positive electrode mixture After mixing 0.500 g of sulfur (manufactured by Aldrich, purity 99.998%) and 0.214 g of carbon (MSC30) in a mortar, the mixture of sulfur carbon was put in a hermetic stainless steel container. . This container was heat-treated in an electric furnace to prepare a sulfur carbon composite. In the heat treatment, the temperature was raised from room temperature to 150 ° C. at 10 ° C./min, held at 150 ° C. for 6 hours, further heated to 300 ° C. at 10 ° C./min, held for 2.75 hours, and then It was carried out by natural cooling.
The obtained sulfur carbon composite and the solid electrolyte powder prepared in the production example were mixed at a mass ratio of 50:50, and this mixture was mixed at room temperature (25 ° C.) in argon with a planetary ball mill (manufactured by Fritsch: Model No. P-7). ), Mechanical milling was performed at a rotational speed of 370 rpm for 5 hours to obtain a positive electrode mixture.

(5) Production of an all-solid-state lithium ion battery 60 mg of the inorganic solid electrolyte powder (glass) produced in the production example was put into a ceramic cylinder having a diameter of 10 mm, and pressure-molded to form an electrolyte layer (electrolyte sheet, inorganic solid electrolyte powder). The weight per unit area was 76.4 mg / cm ² ), and 6.9 mg of the positive electrode mixture prepared in (4) was added and pressure-molded to obtain a positive electrode layer. The negative electrode composite sheet prepared in (1) (negative electrode active material amount: 2.94 mg, negative electrode composite weight per unit area: 5.51 mg / cm ² ) was punched out using a punch having a diameter of 10 mm. The negative electrode mixture layer side of the sheet punched from the side opposite to the positive electrode layer was pressure-molded so as to be in contact with the electrolyte layer to obtain a negative electrode layer. The pressure when pressure-molding the electrolyte layer and the negative electrode layer was the same as that of the half cell. Next, as a lithium source, 2.1 mg of lithium foil (Honjo Metal Co., Ltd.) was bonded to the positive electrode layer side and pressure molded. The pressure applied after sticking the lithium foil was the same as the pressure applied when pressure-molding the reference electrode layer (LiIn alloy) of the half cell. Finally, the periphery of the cell was screwed in four places every 90 degrees to pressurize in the stacking direction. In this manner, an all-solid lithium ion battery having a four-layer structure was produced.

(6) Evaluation of all-solid-state lithium battery About the manufactured all-solid-state lithium ion battery, a constant current (CC) charge (Li ion insertion to a negative electrode active material) is carried out until the voltage will be 2.65V at 0.1C, and the voltage The battery was charged at a constant voltage (CV) until the current reached 0.01 C (insertion of Li ions into the negative electrode active material). After charging, discharging was performed (Li ion desorption from the negative electrode active material) until the voltage became 0.6 V at 0.1 C.
At this time, the Li ion insertion capacity into the negative electrode active material performed for the first time after manufacturing the battery was 57.8% (2426 mAh / g) of the theoretical capacity of Si (4200 mAh / g).
In Li ion desorption operation from the negative electrode active material following Li ion insertion performed for the first time after manufacturing the battery, Li corresponding to 1.35X (927 mAh / g) remains in the Si as Li desorption finished.

After the above operation, the cycle characteristics of the all-solid lithium battery were evaluated as follows.
About the all-solid-state lithium battery, constant current (CC) charge to 2.65V was carried out at 0.2C, and constant voltage (CV) charge was performed until the electric current became 0.01C with the voltage. Then, constant current (CC) discharge was performed to 0.6V at 0.2C.
The charge / discharge cycle was repeated under these conditions, and the discharge capacity retention ratio [%] after 100 cycles (discharge capacity at 100th cycle / discharge capacity at the first cycle × 100) was calculated. The results are shown in Table 1.

Example 3
60 mg of the inorganic solid electrolyte powder (glass) produced in the production example was put into a ceramic cylinder having a diameter of 10 mm, and pressure-molded to form an electrolyte layer (electrolyte sheet, inorganic solid electrolyte powder basis weight: 76.4 mg / cm ² ). Further, 6.9 mg of the positive electrode mixture prepared in (4) was added and pressure-molded to obtain a positive electrode layer. The negative electrode composite sheet prepared in (1) (negative electrode active material amount: 2.94 mg, negative electrode composite weight per unit area: 5.51 mg / cm ² ) was punched out using a punch having a diameter of 10 mm. The negative electrode mixture layer side of the sheet punched from the side opposite to the positive electrode layer was pressure-molded so as to be in contact with the electrolyte layer to obtain a negative electrode layer. The pressure when pressure-molding the electrolyte layer and the negative electrode layer was the same as that of the half cell. Next, 3.6 mg of lithium foil (Honjo Metal Co., Ltd.) as a lithium source was bonded to the positive electrode layer side and pressure molded. The pressure applied after sticking the lithium foil was the same as the pressure applied when pressure-molding the reference electrode layer (LiIn alloy) of the half cell. Finally, the periphery of the cell was screwed in four places every 90 degrees to pressurize in the stacking direction. In this manner, an all-solid lithium ion battery having a four-layer structure was produced.

About the manufactured all-solid-state lithium ion battery, constant current (CC) charge (Li ion insertion into a negative electrode active material) is carried out until the voltage will be 2.65V at 0.1C, and until the electric current will be 0.01C at the voltage Constant voltage (CV) charging (insertion of Li ions into the negative electrode active material) was performed. After charging, discharging was performed (Li ion desorption from the negative electrode active material) until the voltage became 0.6 V at 0.1 C.
At this time, the Li ion insertion capacity into the negative electrode active material performed for the first time after manufacturing the battery was 98.8% (4150 mAh / g) of the theoretical capacity of Si (4200 mAh / g).
In Li ion desorption operation from the negative electrode active material following Li ion insertion performed for the first time after manufacturing the battery, Li corresponding to 3.86X (2651 mAh / g) remains in the negative electrode active material in the Si, thereby desorbing Li. finished.

After the above operation, the cycle characteristics of the all-solid lithium battery were evaluated as follows.
About the all-solid-state lithium battery, constant current (CC) charge to 2.65V was carried out at 0.2C, and constant voltage (CV) charge was performed until the electric current became 0.01C with the voltage. Then, constant current (CC) discharge was performed to 0.6V at 0.2C.
The charge / discharge cycle was repeated under these conditions, and the discharge capacity retention ratio [%] after 100 cycles (discharge capacity at 100th cycle / discharge capacity at the first cycle × 100) was calculated. The results are shown in Table 1.

Comparative Example 1
60 mg of the inorganic solid electrolyte powder prepared in the production example was put into a ceramic cylinder having a diameter of 10 mm, and pressure-molded to form an electrolyte layer (electrolyte sheet, inorganic solid electrolyte powder basis weight: 76.4 mg / cm ² ). 6.9 mg of the positive electrode mixture prepared in (4) of Example 1 was charged and pressure-molded to obtain a positive electrode layer.
The negative electrode mixture slurry prepared in (1) was vacuum dried at 150 ° C. for 3 hours, and the solvent was removed to obtain a negative electrode mixture. 4.33 mg of this negative electrode mixture (amount of negative electrode active material: 2.94 mg, weight per unit area of negative electrode mixture: 5.51 mg / cm ² ) was pressure-molded so as to be in contact with the electrolyte layer to obtain a negative electrode layer.
The pressure when pressure-molding the electrolyte layer and the negative electrode layer was the same as that of the half cell. Furthermore, as a lithium source, 2.1 mg of lithium foil (made by Honjo Metal) was bonded to the negative electrode layer side and pressure-molded. The pressure applied after sticking the lithium foil was the same as the pressure applied when pressure-molding the reference electrode layer (LiIn alloy) of the half cell. Finally, the periphery of the cell was screwed in four places every 90 degrees to pressurize in the stacking direction. In this manner, an all-solid lithium ion battery having a four-layer structure was produced.

The produced all solid lithium ion battery was discharged at a charge / discharge rate of 0.1 C until the voltage reached 0.6V.
After that, constant current (CC) charge (insertion of Li ions into the negative electrode active material) to 2.65 V at 0.2 C, and constant voltage (CV) charge (negative electrode active material) until the current reaches 0.01 C at that voltage. Li ion insertion). Thereafter, constant current (CC) discharge (desorption of Li ions from the negative electrode active material) was performed at 0.2 C up to 0.6 V.
At this time, the Li ion insertion capacity into the negative electrode active material performed for the first time after manufacturing the battery was 30.7% (1292 mAh / g) of the theoretical capacity of Si (4200 mAh / g).
In the Li ion desorption operation from the negative electrode active material following the first Li ion insertion after battery manufacture, Li corresponding to 0.025X (16.9 mAh / g) remains in the negative electrode active material in the Si desorption. I finished the release.
After the above operation, the cycle characteristics of the all-solid lithium battery were evaluated as follows.
About the all-solid-state lithium battery, constant current (CC) charge to 2.65V was carried out at 0.2C, and constant voltage (CV) charge was performed until the electric current became 0.01C with the voltage. Then, constant current (CC) discharge was performed to 0.6V at 0.2C.
The charge / discharge cycle was repeated under these conditions, and the discharge capacity retention ratio [%] after 100 cycles (discharge capacity at 100th cycle / discharge capacity at the first cycle × 100) was calculated. The results are shown in Table 1.

  From Table 1, the Li ion insertion capacity into the negative electrode active material, which is performed for the first time after manufacturing the battery, is not less than (20% of the theoretical capacity [mAh / g]) of the negative electrode active material as compared with Comparative Example 1, and this is performed for the first time after manufacturing the battery. Example 2 and Example in which, in Li ion desorption from the negative electrode active material following Li ion insertion, lithium having a capacity corresponding to 0.03X or more and 50X or less was left in the negative electrode active material to terminate the discharge. 3 shows that the discharge capacity retention rate after 100 cycles is high.

  As described above, according to the charging / discharging method of the present invention, for example, even when Si is used as the negative electrode active material, if Li corresponding to the irreversible capacity is left in Si, the all-solid lithium battery Even if charging / discharging is repeated, the cycle characteristics can be prevented from deteriorating.

The charging / discharging control system, the charging / discharging control circuit, and the charging / discharging control program for implementing the charging / discharging method of the all-solid-state battery of the present invention can be used for an apparatus or a device that charges a lithium ion battery.
The all solid state battery of the present invention can be used as a battery for a portable information terminal, a portable electronic device, a small electric power storage device for home use, a motorcycle using a motor as a voltage source, an electric vehicle, a hybrid electric vehicle, or the like.

Claims (6)

A negative electrode layer;
An electrolyte layer containing an inorganic solid electrolyte;
An all solid state battery comprising:
At 0.2C, constant current (CC) charge up to 2.65V, and at constant voltage (CV) charge until current reaches 0.01C at a voltage of 2.65V. An all-solid-state battery having a discharge capacity maintenance rate of 50% or more after 100 cycles under conditions of a charge / discharge cycle in which current (CC) discharge is performed.   The all-solid-state battery according to claim 1, wherein the negative electrode layer includes a negative electrode active material and an inorganic solid electrolyte.   The all-solid-state battery according to claim 2, wherein the negative electrode active material includes one or more metals or alloys selected from silicon, tin, carbon, magnesium, aluminum, and gallium.   4. The all-solid-state battery according to claim 2, wherein the negative electrode active material has an average particle size of 0.01 μm to 100 μm, and the inorganic solid electrolyte has an average particle size of 0.01 μm to 100 μm. The all-solid-state battery according to any one of claims 1 to 4, wherein the inorganic solid electrolyte is glass satisfying a composition represented by the following formula (1) or glass ceramic satisfying a composition represented by the following formula (1).
Li _{a Mb} P _c S _d (1)
(In the formula, M represents an element selected from B, Zn, Si, Cu, Ga and Ge. Ad represents the composition ratio of each element, and a: b: c: d represents 1 to 12: 0-0.2: 1: 2-9 are satisfied.) Li ion insertion capacity [mAh / g] into the negative electrode active material, which is performed for the first time after battery manufacture, is not less than (20% of theoretical capacity [mAh / g] of the negative electrode active material),
In the Li ion desorption from the negative electrode active material following the first Li ion insertion performed for the first time, the charging of the all-solid-state battery that ends discharge by leaving lithium in a capacity corresponding to 0.03X or more and 50X or less in the negative electrode active material. Discharge method.
(X is the insertion of Li ions into the negative electrode active material for the first time after half-cell production, and at 0.5 mA / cm ² , Li ions are inserted until the negative electrode active material potential becomes 0.01 V vs. Li / Li ⁺ , then 0.01Vvs.Li/Li ⁺ a, by inserting Li ions until 0.127mA / cm ^2, was desorbed Li ions at 0.5 mA / cm ² until the potential 1.52Vvs.Li/Li ⁺ In this case, the Li capacity remaining in the negative electrode active material.
However, the half cell that determines X includes a structure in which a negative electrode layer and an electrolyte layer are laminated, and the negative electrode active material included in the negative electrode layer is the same as the negative electrode active material included in the negative electrode layer of the all-solid battery, The amount per layer unit area is the same, and the inorganic solid electrolyte included in the electrolyte layer is the same as the inorganic solid electrolyte included in the electrolyte layer of the all-solid battery, and the amount per unit area of the electrolyte layer is the same. . )

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