JP2022020387A - Solid electrolyte layer for all-solid secondary battery and all-solid secondary battery - Google Patents

Abstract

To provide a solid electrolyte layer for an all-solid secondary battery, which can also effectively suppress the generation of an inner side short circuit to a charge under a high rate charging and discharging condition while reducing a layer thickness, and also have a manufacturing property, and provide the all-solid secondary battery with the solid electrolyte layer.SOLUTION: The present invention provides a solid electrolyte layer for an all-solid secondary battery, containing: a sulfide-based inorganic solid electrolyte having a lithium ion conduction property; and a solid compound which can be reacted with a lithium metal, and the all-solid secondary battery with this solid electrolyte layer.SELECTED DRAWING: Figure 1

Description

The present invention relates to a solid electrolyte layer for an all-solid-state secondary battery and an all-solid-state secondary battery.

In the all-solid-state secondary battery, the negative electrode, the electrolyte, and the positive electrode are all solid, and the safety and reliability, which are the problems of the battery using the organic electrolytic solution, can be greatly improved. It is also said that it will be possible to extend the service life. Further, the all-solid-state secondary battery can have a structure in which electrodes and electrolytes are directly arranged side by side and arranged in series. Therefore, it is possible to increase the energy density as compared with a secondary battery using an organic electrolytic solution, and it is expected to be applied to an electric vehicle, a large storage battery, or the like.

Normally, in a lithium secondary battery, when the generated lithium metal dendrite grows and reaches the positive electrode due to repeated charging and discharging, an internal short circuit occurs and the function as a battery is lost. In particular, all-solid-state secondary batteries are prone to internal short circuits due to dendrites. In the all-solid-state secondary battery, the electrolyte layer arranged between the positive and negative electrodes is replaced with the solid electrolyte layer, and the electrolyte layer is also formed of the solid material. Therefore, the voids remaining between the solid materials forming the solid electrolyte layer. This is because the dendrite easily grows through the (pinhole). Therefore, in all-solid-state secondary batteries, suppressing the occurrence of internal short circuits due to the growth of dendrites has become an urgent issue.

Therefore, a technique for preventing the growth of dendrites and preventing the occurrence of an internal short circuit is being studied.
For example, in Patent Document 1, a solid electrolyte layer interposed between a positive electrode and a negative electrode is formed of a powder molded body obtained by molding a solid electrolyte powder, and reacts with lithium metal in the gaps between the powders of the powder molded body. An all-solid-state lithium secondary battery in which an ionic liquid is present as a liquid substance that produces an electronic insulator is described.
Further, Patent Document 2 describes an all-solid-state lithium battery including a solid electrolyte layer containing a sulfide solid electrolyte material and an inorganic solid material represented by a specific formula. In the all-solid-state lithium battery of Patent Document 2, by setting the average particle size of each of the sulfide solid electrolyte material and the inorganic solid material to specific conditions, the generation of voids in the sulfide solid electrolyte material is suppressed and the growth of dendrite is promoted. It is a physical prevention.

Further, as a technique for preventing the occurrence of an internal short circuit due to pressure restraint from the outside of the battery during use, Patent Document 3 describes the following solid electrolyte layer containing a first solid electrolyte and a second solid electrolyte as a spacer. All-solid-state lithium secondary batteries provided are described.

Japanese Unexamined Patent Publication No. 2009-21910 Japanese Unexamined Patent Publication No. 2016-081905 Japanese Unexamined Patent Publication No. 2011-081915

In an all-solid-state secondary battery in which the constituent layers such as the positive electrode active material layer, the negative electrode active material layer, and the solid electrolyte layer are formed of a solid material (solid particles), the constituent layers or the constituent layers are usually used in order to exhibit the desired battery performance. The all-solid-state secondary battery is pressurized to bring the solid particles into contact or close contact with each other. Even when such a pressurizing step is performed, the all-solid-state secondary battery has a great advantage in industrial manufacturing that it can be formed into a long sheet and continuously manufactured.

The demand for improved battery performance for all-solid-state secondary batteries has been increasing in recent years due to the rapid progress in research and development of high performance and practical application of electric vehicles, and the high degree of attention. There is. Increasing the energy density is effective for improving the battery performance, and in order to realize this, a technique for reducing the battery volume by thinning the solid electrolyte layer is being studied. Further, the demand for an all-solid-state secondary battery is not only to improve battery performance, but also to apply charge / discharge (high-rate charge / discharge) at a high current density, which enables quick charging, for example.

However, the thinner the solid electrolyte layer, the easier it is for the dendrites to reach the positive electrode, which causes an early occurrence of an internal short circuit. Further, when charging is performed under high-rate charging / discharging conditions, the generation and growth of dendrites are greatly promoted. Therefore, in order to meet the demands of recent years, the all-solid-state secondary battery is used for the thinning of the solid electrolyte layer and the application of high-rate charge / discharge conditions while maintaining the above-mentioned great advantages in industrial manufacturing. However, it is required that the occurrence of internal short circuit can be effectively suppressed.

Under such circumstances, the present inventors have proceeded with studies on suppressing the occurrence of internal short circuits, and further studies have been made to solve the urgent problem peculiar to all-solid-state secondary batteries that internal short circuits are likely to occur. And it turned out that there is room for improvement. That is, as will be described later, the technique described in Patent Document 1 is difficult to apply to a continuous manufacturing method, and may not be able to contribute to a great advantage in industrial manufacturing. Further, in the technique described in Patent Document 2 in which the generation of voids is suppressed by simply using two kinds of materials in combination, the above-mentioned conditions such as thinning of the solid electrolyte layer and charging under high-rate charge / discharge conditions are further applied. There was room to consider suppressing the occurrence of internal short circuits. Patent Document 3 does not study at all about suppressing the occurrence of an internal short circuit by dendrites.

The present invention provides a solid electrolyte layer for an all-solid-state secondary battery that can effectively suppress the occurrence of internal short circuits even when charging under high-rate charge / discharge conditions while thinning the layer, and enables continuous production. The challenge is to provide. Another object of the present invention is to provide an all-solid-state secondary battery provided with the solid electrolyte layer for the all-solid-state secondary battery.

As a result of various studies, the present inventors have made a lithium metal produced (precipitated) by charging by coexisting a solid compound capable of reacting with a lithium metal with a sulfide-based inorganic solid electrolyte in the solid electrolyte layer. It was found that the arrival of the dendrite to the positive electrode can be suppressed by chemically reacting with the solid compound before or during the growth of the dendrite. In addition, the growth of dendrite by the chemical reaction with the solid compound can be suppressed as long as the solid compound is present, and can be realized even if the solid electrolyte layer is thinned or charged under high-rate charge / discharge conditions. I found out what I could do. Furthermore, since the solid compound coexists in the solid electrolyte layer in a solid state, it can be applied to a continuous manufacturing method, the occurrence of internal short circuits is highly suppressed, and an all-solid-state secondary battery capable of exhibiting high battery performance can be obtained. We also found that it can be manufactured with high productivity by taking advantage of its great manufacturing advantages. The present invention has been further studied based on these findings and has been completed.

That is, the above problem was solved by the following means.
<1> A solid electrolyte layer for an all-solid secondary battery containing a sulfide-based inorganic solid electrolyte having lithium ion conductivity and a solid compound capable of reacting with a lithium metal.
<2> The solid electrolyte layer for a solid secondary battery according to <1>, wherein the solid compound is an inorganic oxide.
<3> The solid compound according to <1> or <2>, wherein the solid compound contains at least one metal element selected from the group consisting of Ti, V, Cr, Mn, Fe, Co, Ni and Cu. Solid electrolyte layer for next battery.
<4> The solid electrolyte layer for a solid secondary battery according to any one of <1> to <3>, wherein the solid compound is an oxide containing each element of Al, Ti, P and Si.
<5> The solid electrolyte layer for a solid secondary battery according to any one of <1> to <4>, wherein the solid compound is represented by the following composition formula.
Composition formula: Li _{(1 + x + y)} Al _x Ti _(2-x) Si _y P _(3-y) O ₁₂
However, x and y are each more than 0 and less than 1.0.
<6> The solid electrolyte layer for a solid secondary battery according to <5>, wherein a part of Ti is substituted with Ge in the above composition formula.
<7> An all-solid-state secondary battery provided with the solid electrolyte layer for a solid-state secondary battery according to any one of <1> to <6> above.

INDUSTRIAL APPLICABILITY The present invention can effectively suppress the occurrence of an internal short circuit even when charging under high-rate charge / discharge conditions while thinning the layer, and is capable of continuous production and has excellent production characteristics. A solid electrolyte layer for a battery can be provided. Further, the present invention can provide an all-solid-state secondary battery provided with the solid electrolyte layer for the all-solid-state secondary battery.

It is a vertical sectional view schematically showing the all-solid-state secondary battery which concerns on a preferable embodiment of this invention. FIG. 2 is a charge / discharge curve showing the charge / discharge result in the charge / discharge test of the all-solid-state secondary battery manufactured in Example 1. FIG. 3 is a charge / discharge curve showing the charge / discharge result in the charge / discharge test of the all-solid-state secondary battery manufactured in Comparative Example 1.

In the present invention, the numerical range represented by using "-" means a range including the numerical values before and after "-" as the lower limit value and the upper limit value.
In the present invention, the indication of a compound (for example, when referred to as a compound at the end) is used to mean that the compound itself, its salt, and its ion are included. Further, it is meant to include a derivative which has been partially changed, such as by introducing a substituent, as long as the effect of the present invention is not impaired.

[Solid electrolyte layer]
The solid electrolyte layer for an all-solid secondary battery of the present invention (sometimes referred to simply as a solid electrolyte layer) contains a sulfide-based inorganic solid electrolyte and a solid compound capable of reacting with a lithium metal.
When the solid electrolyte layer contains a sulfide-based inorganic solid electrolyte and a solid compound, the lithium metal generated by charging is chemically reacted with the solid compound before or during the growth to dendrite to the positive electrode of dendrite. Can be blocked from reaching. Therefore, even under conditions where internal short circuits are likely to occur, such as thinning of the solid electrolyte layer and / or application of high-rate charge / discharge conditions, the technique of physically blocking the growth of dendrites as in Patent Documents 2 and 3 is used. It is possible to suppress the occurrence of internal short circuit at a high level.

Moreover, since the present invention using a solid compound allows the solid compound to coexist in the solid electrolyte layer in a solid state, it can be applied to a continuous production method including a pressurization step, and is an industry peculiar to an all-solid secondary battery. It is also possible to take advantage of the great manufacturing advantages.

As described above, the present inventors simply suppress the occurrence of an internal short circuit by chemically reacting the lithium metal forming the dendrite with a solid compound rather than a physical means before or during the growth to the dendrite. However, the present invention was completed by discovering for the first time that the advantages of the all-solid-state secondary battery can be effectively utilized from the viewpoint of the manufacturing method.
Therefore, the solid-state electrolyte layer of the present invention is an all-solid-state secondary battery that can effectively suppress the occurrence of internal short circuits while realizing high battery performance for practical use of electric vehicles. It can be manufactured with high productivity by taking advantage of the great industrial manufacturing advantages peculiar to the battery.

<Sulfide-based inorganic solid electrolyte>
The sulfide-based inorganic solid electrolyte preferably has lithium ion conductivity and further electron insulating properties. As the sulfide-based inorganic solid electrolyte, a solid electrolyte usually used for an all-solid secondary battery can be appropriately selected and used, and examples thereof include those having a sulfur element as a main component as an anion element.
The sulfide-based inorganic solid electrolyte is not particularly limited, and for example, Li ₂ SP ₂ S ₅ , Li ₂ SP ₂ S ₅ -LiI, Li ₂ SP ₂ S ₅ -LiCl, and the like. Li ₂ SP 2 S ₅ -LiBr, Li ₂ SP ₂ S ₅ -Li ₂ O, Li ₂ SP ₂ S ₅ -Li ₂ O-LiI, Li ₂ S _- SiS ₂ , Li ₂ S- SiS ₂ -LiI, Li ₂ S-SiS ₂ -LiBr, Li ₂ S-SiS ₂ -LiCl, Li ₂ S-SiS ₂ -B ₂ S ₃ -LiI, Li ₂ S-SiS ₂ -P ₂ S ₅ -LiI , Li ₂ SB ₂ S ₃ , Li ₂ SP ₂ S ₅ -Z _m Sn (where m and _n indicate positive numbers; Z indicates any of Ge, Zn, Ga). , Li ₂ S-GeS ₂ , Li ₂ S-SiS ₂ -Li ₃ PO ₄ , Li ₂ S-SiS ₂ -Li _x MO _y (where x, y indicate positive numbers; M is P, Si, Any of Ge, B, Al, Ga, In), Li ₁₀ GeP ₂ S ₁₂ and the like can be mentioned. Further, the sulfide-based inorganic solid electrolyte may be amorphous, crystalline, or glass ceramics.

The sulfide-based inorganic solid electrolyte preferably has an ionic conductor having a Li element, a P element, and an S element. The ionic conductor is usually composed of a Li cation and an anion structure containing P and S. Above all, it is preferable that the ion conductor contains the PS 43 _- structure as the main body (50 mol% or more) of the ^anionic structure. Above all, the ratio of the PS ^43- structure is preferably 70 mol% or more, more preferably 90 mol% or more, based on the _total anion structure of the ionic conductor. The ratio of PS ^43- _structure can be determined by Raman spectroscopy, nuclear magnetic resonance spectroscopy (NMR), X-ray photoelectron spectroscopy (XPS), and the like.

Further, it is preferable that the sulfide-based inorganic solid electrolyte mainly contains the above-mentioned ionic conductor. The ratio of the ionic conductor in the sulfide-based inorganic solid electrolyte is preferably 65 mol% or more, more preferably 75 mol% or more. Further, the sulfide-based inorganic solid electrolyte may be composed of only the above-mentioned ionic conductor, or may contain other components. Examples of other components include LiI. The ratio of LiI is, for example, 5 mol% or more, preferably 20 mol% or more. On the other hand, the ratio of LiI is, for example, 35 mol% or less, preferably 30 mol% or less. In particular, the sulfide-based inorganic solid electrolyte is xLiI · (100−x) (yLi ₂ S · (1-y) P ₂ S ₅ ) (20 ≦ x ≦ 30, 0.7 ≦ y ≦ 0.8). It is preferable to have a composition. In addition, y is preferably 0.72 or more, and more preferably 0.74 or more. Further, y is preferably 0.78 or less, and more preferably 0.76 or less.

The sulfide-based inorganic solid electrolyte preferably has high lithium ion conductivity, and the lithium ion conductivity at room temperature (25 ° C.) is preferably, for example, 1 × 10 ^-4 S / cm or more, and 1 × 10 ⁻ . It is more preferably ³ S / cm or more.

The sulfide-based inorganic solid electrolyte is preferably in the form of powder. In this case, the average particle size of the sulfide-based inorganic solid electrolyte is not particularly limited, and is preferably 0.01 to 100 μm, for example. The average particle size can be obtained, for example, by measuring the particle size of a certain amount of solid electrolyte observed with a scanning electron microscope (SEM) and calculating the average value.

In the present invention, the sulfide-based inorganic solid electrolyte may have at least lithium ion conductivity, and has ion conductivity of a metal belonging to Group 1 or Group 2 of the periodic table other than lithium. May be good. Further, as the sulfide-based inorganic solid electrolyte, in addition to those having lithium ion conductivity, those having ion conductivity of a metal belonging to Group 1 or Group 2 of the Periodic Table other than lithium can also be used in combination. ..

<Solid compound that can react with lithium metal>
The solid compound capable of reacting with the lithium metal is a compound that chemically reacts with the lithium metal and takes a solid state at normal temperature (25 ° C.) and normal pressure (1 atm).
The reaction of the solid compound with the lithium metal is not particularly limited as long as it can be converted into another compound, and examples thereof include a redox reaction, a substitution reaction, and an elimination reaction. As for the reaction with the lithium metal, a redox reaction in which the solid compound comes into contact with the lithium metal to reduce itself and oxidize the lithium metal is preferable. The reaction with the lithium metal is preferably a reaction that occurs specifically with respect to the lithium metal (0-valent lithium), and it is desirable that the reaction with the lithium ion does not occur in terms of maintaining the battery performance.
The reaction with the lithium metal may occur regardless of the operation (charging / discharging) of the all-solid-state secondary battery, but it is preferable that the reaction occurs at least during charging. The conditions under which the reaction occurs are not particularly limited, and may occur under the operating environment conditions of the all-solid-state secondary battery, and it is preferable that the reaction occurs at normal temperature and pressure.
Other compounds produced by the reaction of the solid compound with the lithium metal are not particularly limited, but usually include compounds that do not cause an internal short circuit, compounds that do not promote the growth of dendrites, and the like. For example, a compound having electronic insulation (although it cannot be uniquely determined, the conductivity at a measurement temperature of 25 ° C. is ^10-9 S / cm or less) can be mentioned. For example, as the reaction product in the redox reaction, a compound in which oxidized lithium ions are incorporated into the (crystal) structure of itself (solid compound) is preferable.

The reaction with the lithium metal and other compounds will be specifically described below by taking a solid compound represented by the following composition formula as an example.

Composition formula: Li _{(1 + x + y)} Al _x Ti _(2-x) Si _y P _(3-y) O ₁₂
(However, x and y are each more than 0 and less than 1.0.)

When the solid compound comes into contact with the lithium metal, the lithium metal is oxidized to generate lithium ions and electrons, as shown below. On the other hand, the solid compound (Ti element) is reduced by electrons generated by oxidation of the lithium metal, and the valence of the Ti element in the solid compound changes from tetravalent to trivalent.

Lithium metal (oxidation): Li → Li ^＋ ＋ e ^－
Solid compound (reduction) ^: Ti ⁴⁺ + e- → Ti ³⁺

At this time, if nmol of lithium metal reacts with 1 mol of the solid compound, n mol of Ti element among (2-x) mol of Ti element in the solid compound starts from tetravalent according to the following reaction formula. Reduced to trivalent, lithium ions are incorporated into the crystal structure of the solid compound. In this way, the compound shown in the following composition formula incorporating lithium ions is produced.
In this reaction, (2-x—n) moles of Ti element are not reduced and remain tetravalent.
Up to (2-x) moles of lithium metal can react with the solid compound represented by the above composition formula.

Li _{(1 + x + y)} Al _x Ti _(2-x) Si _y P _(3-y) O ₁₂ + nLi
→ Li _{(1 + x + y + n) x} Al _x Ti _(2-x) Si _y P _(3-y) O ₁₂

The solid compound may be any compound that takes a solid state at normal temperature and pressure, and a compound that causes the above reaction, particularly a compound capable of incorporating lithium ions generated by a redox reaction into the crystal structure is preferable.
Examples of such a compound include an organic compound and an inorganic compound, and an inorganic oxide is preferable and a metal oxide is more preferable in that the above-mentioned redox reaction can occur and lithium ions can be incorporated into the crystal structure. ..
The organic compound is not particularly limited, and examples thereof include alkyl halides such as octadecyl bromide.

Examples of the inorganic oxide include oxides of metal elements, semi-metal elements, and non-metal elements, and the crystal structure does not necessarily have to be in the form of an oxide, and has a crystal structure having an anion such as a phosphate ion. Even if it is a solid compound, it includes a compound that can be represented by the material composition of an oxide (for example, a compound represented by each composition formula described later). Such inorganic oxides are not particularly limited, and specific examples thereof include perovskite-type oxides, spinel oxides, and layered oxides.
As the inorganic oxide, an oxide containing at least one metal element (referred to as a metal oxide in the present invention) is preferable, and Ti is easy to undergo an oxidation-reduction reaction with a lithium metal by easily causing a valence change. , V, Cr, Mn, Fe, Co, Ni and Cu are more preferably oxides (metal oxides) containing at least one metal element selected from the group, and Ti, Mn or Co metal elements at least. A metal oxide containing one kind is more preferable, and a metal oxide containing at least Ti is particularly preferable. The elements other than the above-mentioned metal elements constituting the inorganic oxide and the metal oxide are not particularly limited, and various elements such as metal elements, semi-metal elements, and non-metal elements are appropriately selected.

The solid compound is preferably an oxide containing each element of Al, Ti, P and Si as a metal oxide containing at least Ti, and more preferably an oxide containing Li. Since the redox potential of this oxide is close to that of lithium ions, a redox ^{reaction with a lithium metal occurs rapidly, and lithium ions, for example, while maintaining a crystal structure having a phosphate ion (PO 43-} ₎ . Can be taken in (stabilization of crystal structure). The oxide containing each element of Al, Ti, P and Si is not particularly limited, and examples thereof include metal oxides represented by the composition formula described later.

In the above-mentioned inorganic oxide and metal oxide, a part of the constituent elements may be replaced with another element, and in the present invention, the inorganic oxide and the metal oxide each have a part of the constituent elements. Includes oxides substituted with other elements. Examples of such an oxide include an oxide in which a part of Ti constituting the metal oxide is replaced with Ge or the like.

The solid compound is preferably an oxide represented by the following composition formula. This oxide has high reactivity with lithium metal and can effectively prevent the occurrence of internal short circuit due to lithium dendrite. Further, this compound also has lithium ion conductivity, and it is possible to suppress a decrease in lithium ion conductivity of the solid electrolyte layer when used in combination with a sulfide-based inorganic solid electrolyte. Moreover, the reaction product with the lithium metal also exhibits lithium ion conductivity, and the high lithium ion conductivity obtained by the sulfide-based inorganic solid electrolyte can be maintained while suppressing the occurrence of internal short circuit.

Composition formula: Li _{(1 + x + y)} Al _x Ti _(2-x) Si _y P _(3-y) O ₁₂

In the above composition formula, x is more than 0 and less than 1.0, and can be, for example, 0.1 to 0.5. y is more than 0 and less than 1.0, and can be, for example, 0.1 to 0.3.

The oxide represented by the above composition formula has a Li-substituted NASICON (Na Super Ionic Controller) type main crystal phase, and can take in lithium ions while maintaining the crystal structure. This oxide can be represented by Li ₂ O-Al ₂ O ₃ -SiO ₂ -P ₂ O ₅ -TiO ₂ in the oxide composition (material composition) of each element.

The oxide represented by the above composition formula may be partially substituted with Ge, and includes an oxide represented by the following composition formula (G). In the following composition formula (G), the amount of Ti substituted with Ge is not particularly limited and can be appropriately set.

Composition formula (G): Li _{(1 + x + y)} Al _x (Ti, Ge) _(2-x) Si _y P _(3-y) O ₁₂
X and y in the composition formula (G) are more than 0 and less than 1.0, respectively, and are synonymous with x and y in the above composition formula.

The oxide represented by the composition formula (G) has a Li-substituted NASICON type main crystal phase, and can take in lithium ions while maintaining the crystal structure. This oxide can be represented by Li ₂ O-Al ₂ O ₃ -SiO ₂ -P ₂ O ₅ -TiO ₂ -GeO ₂ in the oxide composition (material composition) of each element.

The solid compound may be appropriately synthesized or prepared and used, or a commercially available product may be used. The oxide represented by each of the above compositions is commercially available, for example, under the trade name "LICGC" (registered trademark, manufactured by OHARA Corporation).

The solid compound is preferably in the form of powder. In this case, the average particle size of the solid compound is not particularly limited, and is preferably 0.01 to 100 μm, for example. The average particle size can be obtained, for example, by measuring the particle size of a certain amount of solid electrolyte observed with a scanning electron microscope (SEM) and calculating the average value.

<Other materials (compounds)>
The solid electrolyte layer may contain a compound other than the sulfide-based inorganic solid electrolyte and the solid compound (other compounds). Examples of other compounds include compounds used for the solid electrolyte layer of an all-solid-state secondary battery without particular limitation, and examples thereof include a binder. Examples of the binder include various binders used in all-solid-state secondary batteries, such as a fluorine-containing binder such as polyvinylidene fluoride (PVDF) and a rubber binder such as butadiene rubber. can. Further, in order to physically fill the voids generated in the solid electrolyte layer, an ionic liquid having lithium ion conductivity or the like may be further contained as long as the action and effect of the present invention are not impaired, but continuous production is performed. It is preferable that the liquid component is not contained.

It is preferable that the sulfide-based inorganic solid electrolyte and the solid compound contained in the solid electrolyte layer are uniformly dispersed.
The solid electrolyte layer of the present invention may contain one kind or two or more kinds of a sulfide-based inorganic solid electrolyte and a solid compound, respectively.
The content of the sulfide-based inorganic solid electrolyte contained in the solid electrolyte layer is usually 0.1% by volume or more, and 0.3% by volume or more, based on the total volume of the sulfide-based inorganic solid electrolyte and the solid compound. Is preferable. The upper limit is not particularly limited, and is preferably 99.9% by volume or less, more preferably 99.5% by volume or less. The content of the solid compound is not particularly limited and is appropriately determined, but in terms of ionic conductivity, it is 0.1 to 50% by volume with respect to the total volume of the sulfide-based inorganic solid electrolyte and the solid compound. It is preferably 0.3 to 47% by volume, more preferably 0.5 to 45% by volume. The total content of the sulfide-based inorganic solid electrolyte and the solid compound contained in the solid electrolyte layer is, for example, preferably 80% by mass or more, more preferably 90% by mass or more, and 95% by mass, on a mass basis. It is more preferably mass% or more. The upper limit of the total content is preferably 99.9% by mass or less, and more preferably 99.5% by mass or less.

The thickness of the solid electrolyte layer is not particularly limited, but is, for example, 1000 μm or less, preferably 500 μm or less, and more preferably 300 μm or less. Further, the lower limit of the thickness is, for example, 1 μm or more, preferably 5 μm or more.
Since the solid electrolyte layer of the present invention contains the solid compound as described above, it can be thinned without impairing the effect of suppressing the occurrence of internal short circuits. As a result, the volume of the all-solid-state secondary battery can be reduced and the energy density can be increased. The thickness of the solid electrolyte layer at this time can be appropriately set in consideration of the energy density and the like regardless of the thickness in the above range, and is preferably 5 to 150 μm, preferably 7 to 100 μm, for example. Is more preferable, and 10 to 50 μm is even more preferable.
The thickness of the solid electrolyte layer means the average thickness of the solid electrolyte layer.

The solid electrolyte layer of the present invention can be produced by a usual method, a sulfide-based inorganic solid electrolyte and a solid compound, and a method of appropriately forming a mixture of other compounds by pressure molding or the like.
The solid electrolyte layer of the present invention can also be produced by applying a continuous production method having the above advantages, which is preferable in terms of productivity. For example, a composition (preferably a slurry) containing a sulfide-based inorganic solid electrolyte and a solid compound, and further other compounds as appropriate is prepared, and this composition is applied to a substrate and dried to form a long shape. The solid electrolyte layer can be produced by a continuous production method such as a roll-to-roll method. In such a roll-to-roll method or the like, it is possible to pressurize the coated dry membrane, the solid electrolyte layer, or the like by a usual method such as a roll press method. The method for applying the composition, the method for drying (conditions), the method for pressurizing (pressurizing conditions), and the like can be appropriately set.

[All-solid-state secondary battery]
The all-solid-state secondary battery of the present invention comprises the above-mentioned solid electrolyte layer of the present invention.
The all-solid-state secondary battery of the present invention provided with this solid electrolyte layer inhibits the growth of lithium metal dendrites even when high-rate charge / discharge conditions are applied as well as normal charging conditions as charge / discharge conditions. The occurrence of internal short circuit can be effectively suppressed. Further, even if the solid electrolyte layer is thinned to the above thickness to improve the energy density, the occurrence of internal short circuit can be effectively suppressed. Moreover, as a manufacturing method, a continuous manufacturing method having a great advantage in industrial manufacturing can be applied without causing deterioration of battery performance.

The all-solid-state secondary battery of the present invention includes a positive electrode active material layer, a negative electrode active material layer, and a solid electrolyte layer. Specifically, the positive electrode active material layer, the negative electrode active material layer, and the solid electrolyte layer of the present invention are provided between the positive electrode active material layer and the negative electrode active material layer.
As shown in FIG. 1, an example of this is shown in FIG. 1, in which the preferred lithium ion all-solid-state secondary battery 10 of the present invention has a negative electrode current collector 1, a negative electrode active material layer 2, a solid electrolyte layer 3, and a positive electrode when viewed from the negative electrode side. The active material layer 4 and the positive electrode current collector 5 are provided in this order. Each layer is in contact with each other and has an adjacent structure. By adopting such a structure, during charging, electrons (e ⁻ ) are supplied to the negative electrode side, and lithium ions (Li ⁺ ) are accumulated there. On the other hand, at the time of discharge, the lithium ion (Li ⁺ ) accumulated in the negative electrode is returned to the positive electrode side, and electrons are supplied to the operating portion 6. In the illustrated example, a light bulb is used as a model for the operating portion 6, and the light bulb is turned on by electric discharge.

<Positive electrode active material layer>
The positive electrode active material layer is a layer containing at least a positive electrode active material. Further, the positive electrode active material layer may contain at least one of a conductive auxiliary agent, a binder and an inorganic solid electrolyte in addition to the positive electrode active material.

As the positive electrode active material, a material usually used for an all-solid-state secondary battery can be appropriately selected and used, and a material capable of reversibly inserting and releasing lithium ions is preferable. Examples of the positive electrode active material include an oxide active material. Specific examples of the oxide active material include LiCoO ₂ , LiMnO ₂ , LiNiO ₂ , LiVO ₂ , LiNi _1/3 Co _1/3 Mn _1/3 O ₂ , LiNi _0.5 Co _0.2 Mn _0. Rock salt layered active material such as ₃ O ₂ , spinel type active material such as LiMn ₂ O ₄ , Li (Ni _0.5 Mn _1.5 ) O ₄ , olivine such as LiFePO ₄ , LiMnPO ₄ , LiNiPO ₄ , LiCuPO ₄ Examples include mold active substances. Further, Li ₂ FeSiO ₄ and Li ₂ MnSiO ₄ may be used as the positive electrode active material.
The positive electrode active material is preferably in the form of particles, and the average particle size is not particularly limited, and can be, for example, 0.1 to 50 μm. The method for measuring the average particle size is the same as that of the above-mentioned sulfide-based inorganic solid electrolyte.
The positive electrode active material may contain one kind or two or more kinds.
The content of the positive electrode active material in the positive electrode active material layer is not particularly limited, and is preferably 10 to 97% by volume, more preferably 20 to 95% by volume, and 30 to 90% by volume in terms of solid content of 100% by volume. More preferably, 40 to 85% by volume is particularly preferable.

The surface of the positive electrode active material may be coated with a coat layer. This is because the reaction between the positive electrode active material and the sulfide inorganic solid electrolyte can be suppressed. Examples of the material of the coat layer include lithium ion conductive oxides such as LiNbO ₃ , Li ₃ PO ₄ , and LiPON. The average thickness of the coat layer is preferably in the range of, for example, 1 to 20 nm, and more preferably in the range of 1 to 10 nm.

<Negative electrode active material layer>
The negative electrode active material layer is a layer containing at least the negative electrode active material. Further, the negative electrode active material layer may contain at least one of a conductive auxiliary agent, a binder and an inorganic solid electrolyte in addition to the negative electrode active material.

As the negative electrode active material, a material usually used for an all-solid-state secondary battery can be appropriately selected and used, and a material capable of reversibly inserting and releasing lithium ions is preferable. Examples of the negative electrode active material include a metal active material and a carbon active material.
Examples of the metal active material include In, Al, Si, Sn and the like. On the other hand, examples of the carbon active material include natural graphite, artificial graphite such as highly oriented graphite (HOPG), mesocarbon microbeads (MCMB), hard carbon, soft carbon and the like.
The negative electrode active material is preferably in the form of particles, and the average particle size is not particularly limited, and can be, for example, 0.1 to 50 μm. The method for measuring the average particle size is the same as that of the above-mentioned sulfide-based inorganic solid electrolyte.
The negative electrode active material may contain one kind or two or more kinds.
The content of the negative electrode active material in the negative electrode active material layer is not particularly limited, and is preferably 10 to 97% by volume, more preferably 20 to 95% by volume, and 30 to 90% by volume in terms of solid content of 100% by volume. More preferably, 40 to 85% by volume is particularly preferable.

As the conductive auxiliary agent that may be contained in the positive electrode active material layer and the negative electrode active material layer, those normally used for all-solid-state secondary batteries can be appropriately selected and used. For example, acetylene black and ketjen black can be used. , VGCF, graphite and other carbon materials. Examples of the binder include those described in the sulfide-based inorganic solid electrolyte. As the inorganic solid electrolyte, those usually used for an all-solid secondary battery can be appropriately selected and used, and examples thereof include the above-mentioned sulfide-based inorganic solid electrolyte and oxide solid electrolyte. The thickness of the positive electrode active material layer varies greatly depending on the configuration of the battery, but is preferably in the range of, for example, 0.1 to 1000 μm.
The conductive auxiliary agent, the binder, and the solid electrolyte may each contain one type or two or more types, and the content thereof is appropriately determined.

The binder material that may be contained in the positive electrode active material layer and the negative electrode active material layer is the same as described above. Further, the inorganic solid electrolyte may be the above-mentioned sulfide-based inorganic solid electrolyte, or may be an inorganic solid electrolyte-containing composition having ionic conductivity of a metal belonging to Group 1 or Group 2 of the periodic table other than lithium. Other inorganic solid electrolytes used in solid secondary batteries may be used.
The thickness of the positive electrode active material layer and the negative electrode active material layer varies greatly depending on the configuration of the battery, but is preferably in the range of, for example, 0.1 to 1000 μm.

<Solid electrolyte layer>
The solid electrolyte layer included in the all-solid-state secondary battery is the solid electrolyte layer of the present invention and contains a solid compound. The details of the solid electrolyte layer are as described above. However, the content of the solid compound in the solid electrolyte layer is reduced as compared with that before use by reacting with the lithium metal by using (charging / discharging) the all-solid secondary battery. Whether or not the solid compound is present in the solid electrolyte layer can be confirmed, for example, by composition analysis using energy dispersive X-ray spectroscopy (EDS).

<Current collector>
Examples of the material of the positive electrode current collector that collects the positive electrode active material layer include stainless steel (SUS), aluminum, nickel, iron, titanium, and carbon. Further, as the material of the negative electrode current collector that collects the current of the negative electrode active material layer, for example, SUS, copper, nickel, carbon and the like can be mentioned.

<Other configurations>
With respect to the all-solid-state secondary battery, configurations other than the above configurations can be applied without particular limitation to the usual configurations. For example, a general battery case can be provided. Examples of the battery case include a battery case made of SUS or aluminum.

The all-solid-state secondary battery may have a normal charge control unit that controls the current density during charging.
In the all-solid-state secondary battery, a restraining pressure in the thickness direction may be applied by the restraining member. The type of the restraining member is not particularly limited, and a general restraining member can be used. The confining pressure (surface pressure) is not particularly limited, but is, for example, 0.1 MPa or more, preferably 1 MPa or more. By increasing the confining pressure, it becomes easier to maintain contact between the particles, such as contact between the active material particles and the electrolyte particles. On the other hand, the restraint pressure (surface pressure) is, for example, 400 MPa or less, preferably 300 MPa or less. This is because if the restraining pressure is too large, the restraining member is required to have high rigidity, and the restraining member may become large in size.

The all-solid-state secondary battery is not particularly limited as long as it has the above-mentioned positive electrode active material layer, negative electrode active material layer and solid electrolyte layer. Examples of the shape of the all-solid-state secondary battery include a coin type, a laminated type, a cylindrical type, and a square type.
Further, the above-mentioned all-solid-state secondary battery is provided with a negative electrode active material layer in the manufacturing process of the all-solid-state secondary battery, but the all-solid-state secondary battery of the present invention is not provided with the negative electrode active material layer at the time of manufacturing. It also includes an embodiment of forming by precipitating lithium metal as a negative electrode active material by subsequent charging. Further, the negative electrode active material layer may be provided as a layer formed by depositing or molding a lithium metal powder, or as a lithium metal layer such as a lithium foil and a lithium vapor deposition film.

The all-solid-state secondary battery of the present invention can be manufactured by a usual method. For example, as shown in Examples described later, the positive electrode active material layer, the negative electrode active material layer, and the solid electrolyte layer can be prepared and then laminated to be produced. Each layer can be produced in the same manner as in the method for producing a solid electrolyte layer of the present invention.
The all-solid-state secondary battery of the present invention can also be manufactured by applying a continuous manufacturing method having the above advantages, which is preferable in terms of productivity. For example, a composition (preferably a slurry) capable of forming each layer is applied and dried on the surface of a current collector or a layer already formed to form a long sheet or a laminated body by a roll-to-roll method or the like. It can be manufactured by the continuous manufacturing method of. In such a roll-to-roll method or the like, it is possible to pressurize the coated dry film, the laminated body or the like by a usual method such as a roll press method.

<Initialization>
The all-solid-state secondary battery manufactured as described above is preferably initialized after manufacturing or before use. Initialization is not particularly limited, and can be performed, for example, by performing initial charging / discharging with the press pressure increased, and then releasing the pressure until the pressure reaches the general working pressure of the all-solid-state secondary battery.

[Use of all-solid-state secondary battery]
The all-solid-state secondary battery of the present invention can be applied to various uses. The application mode is not particularly limited, but for example, when it is mounted on an electronic device, it is a notebook computer, a pen input computer, a mobile computer, an electronic book player, a mobile phone, a cordless phone handset, a pager, a handy terminal, a mobile fax, or a mobile phone. Copy, mobile printer, headphone stereo, video movie, LCD TV, handy cleaner, portable CD, mini disk, electric shaver, transceiver, electronic organizer, calculator, memory card, portable tape recorder, radio, backup power supply, etc. Other consumer products include automobiles, electric vehicles, motors, lighting equipment, toys, game equipment, road conditioners, watches, strobes, cameras, medical equipment (pacemakers, hearing aids, shoulder massagers, etc.). Furthermore, it can be used for space use. It can also be combined with a solar cell.

Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited thereto. In the following examples, "parts" and "%" representing the composition are based on mass unless otherwise specified. In the present invention, "room temperature" means 25 ° C.

[Example 1]
An all-solid-state secondary battery having the layer structure shown in FIG. 1 was manufactured as follows.
(Preparation of positive electrode active material layer)
Lithium nickel cobalt manganate: LiNi _0.5 Co _0.2 Mn _0.3 O ₂ (NCM523) as a positive electrode active material, and argylodite-type sulfide-based inorganic solid electrolyte: Li ₆ PS ₅ Cl (particle size 1 μm). Using VGCF (manufactured by Showa Denko Co., Ltd.) as a conductive auxiliary agent, butadiene rubber as a binder, and mesitylen as a dispersion medium, a slurry having an active material ratio of 50% by volume in solid content was prepared. The content in the slurry is 100% by volume of the solid content, 40% by volume of the sulfide-based inorganic solid electrolyte, 5% by volume of the conductive auxiliary agent, 5% by volume of the binder, and the solid content concentration. Was 60% by volume.
Next, the prepared slurry was applied onto a stainless steel (SUS) foil using an applicator so as to have a capacity of 1.7 mAh / cm ² , and dried at 70 ° C. for 4 hours to prepare a positive electrode sheet. ..

(Preparation of negative electrode active material layer)
Artificial graphite (particle size 20 μm) as the negative electrode active material, algyrodite-type sulfide-based inorganic solid electrolyte: Li ₆ PS ₅ Cl (particle size 1 μm), butadiene rubber as the binder, and mesitylen as the dispersion medium. Was used to prepare a slurry having an active material ratio of 50% by volume in the solid content. The content in the slurry was 45% by volume of the sulfide-based inorganic solid electrolyte, 5% by volume of the binder, and 60% by volume of the solid content at 100% by volume of the solid content.
Next, the prepared slurry was applied onto a SUS foil at 2.0 mAh / cm ² using an applicator, and dried at 70 ° C. for 4 hours to prepare a negative electrode sheet.

(Preparation of solid electrolyte layer)
Algyrodite-type sulfide-based inorganic solid electrolyte: Li ₆ PS ₅ Cl (particle size: 1 μm), Li-substituted NASICON-type solid compound: LICGC (registered trademark) PW-01 (product name, manufactured by O'Hara), and a binder (product name, manufactured by O'Hara). A slurry having a solid content concentration of 50% by mass was prepared using a butadiene rubber as a binder) and mesityrene as a dispersion medium. The volume ratio of the sulfide-based inorganic solid electrolyte to the solid compound was 80:20 (sulfide-based inorganic solid electrolyte: solid compound). The content of the binder in the slurry was 5% by volume at 100% by volume of the solid content.
The Li-substituted NASICON type solid compound used is represented by the following composition formula.
Composition formula: Li _{(1 + x + y)} Al _x Ti _(2-x) Si _y P _(3-y) O ₁₂
(X and y are each more than 0 and less than 1.0.)

Next, the prepared slurry was applied onto a SUS foil and dried at 70 ° C. for 4 hours to prepare a solid electrolyte layer sheet.

(Manufacturing of all-solid-state secondary batteries)
The prepared negative electrode sheet and solid electrolyte sheet were cut into 2.5 cm squares to obtain each sheet piece. The solid electrolyte layer of the solid electrolyte sheet piece is superposed on the negative electrode active material layer of the negative electrode sheet piece, and pressed at 392 MPa using a cold isotropic press (CIP) to form the negative electrode sheet piece and the solid electrolyte sheet piece. A bonded body (laminated body) was obtained. In this bonded body, the thickness of the solid electrolyte layer was 20 μm, and the thickness of the negative electrode active material layer was 70 μm.
Next, the prepared positive electrode sheet was cut into 2 cm squares, and the positive electrode sheet was pressed at 392 MPa using CIP to obtain a positive electrode sheet piece. The thickness of the positive electrode active material layer of this positive electrode sheet piece was 70 μm.
Next, the SUS foils on both sides of the bonded body were peeled off, and the SUS foils on the positive electrode sheet pieces were peeled off. Then, the positive electrode active material layer of the positive electrode sheet piece was superposed on the surface of the solid electrolyte layer of the bonded body, and the SUS foil was superposed as the current collectors of the positive electrode and the negative electrode, and tabbing was performed. This was laminated with an aluminum laminating film to obtain a sheet battery.
Next, the obtained sheet battery was constrained in the stacking direction at 200 MPa using a SUS restraint jig, charged to 4.2 V at 0.1 C, and then discharged to 3 V for initialization (chemical conversion treatment). Completed.
In this way, a sheet-shaped all-solid-state secondary battery was manufactured. This all-solid-state secondary battery had a specific capacity of 150 mAh / g-NCM523 at 25 ° C.

[Comparative Example 1]
(Preparation of solid electrolyte sheet for comparison)
In the preparation of the solid electrolyte layer of Example 1, LICGC (registered trademark) was not used, and the volume ratio of the sulfide-based inorganic solid electrolyte and the solid compound was set to 100: 0 (sulfide-based inorganic solid electrolyte: solid compound). Except for this, a comparative solid electrolyte sheet was prepared in the same manner as in the preparation of the solid electrolyte layer of Example 1. The solid content concentration and the content of the binder in the comparative slurry prepared to form the solid electrolyte layer are the same as those prepared in Example 1.
(Manufacturing of all-solid-state secondary batteries for comparison)
In the production of the all-solid secondary battery of Example 1, the solid electrolyte layer of the comparative solid electrolyte sheet cut into 2.5 cm square was superposed on the negative electrode active material layer of the negative electrode sheet piece produced in Example 1. Except for the above, a comparative bonded body of a negative electrode sheet piece and a comparative solid electrolyte sheet piece was obtained in the same manner as in the production of the all-solid secondary battery of Example 1. In this comparative bonded body, the thickness of the solid electrolyte layer was 20 μm, and the thickness of the negative electrode active material layer was 70 μm.
Next, a sheet-shaped comparative all-solid-state secondary battery was manufactured in the same manner as in the production of the all-solid-state secondary battery of Example 1 except that the obtained comparative all-solid-state battery was used.
The comparative all-solid-state secondary battery had a specific capacity of 150 mAh / g-NCM523 at 25 ° C.

[Charge rate test]
A charge rate test was performed on the manufactured all-solid-state secondary battery of Example 1 and the comparative all-solid-state secondary battery of Comparative Example 1 using the charge / discharge evaluation device TOSCAT-3000 (trade name, manufactured by Toyo System Co., Ltd.). The effect of suppressing the occurrence of internal short circuits was evaluated.
That is, each all-solid-state secondary battery was subjected to a charge rate test from 0.1 C to 6.0 C in an environment of 60 ° C. (CC 4.2 V, CV 0.01 C cut).
Specifically, the charge / discharge curve was obtained by sequentially performing the 0.1C charge / discharge step to the 6.0C charge / discharge step as described below.

(1) 0.1C charge / discharge step For each all-solid-state secondary battery, CC charging was performed at 0.1 C up to 4.2 V, and CV charging was performed at 0.01 C cut. After a 30-minute rest, CC discharge was further performed at 0.1 C up to 3 V, CV discharge was performed at a 0.01 C cut, and a 30-minute rest was performed.
(2) 0.2C charge / discharge step For each all-solid-state secondary battery after the 0.1C charge / discharge step, CC charging was performed at 0.2C up to 4.2V, and CV charging was performed at 0.01C cut. After a 30-minute rest, CC discharge was further performed at 0.2 C up to 3 V, CV discharge was performed at a 0.01 C cut, and a 30-minute rest was performed.
(3) 0.5C charge / discharge step For each all-solid-state secondary battery after the 0.2C charge / discharge step, CC charging was performed at 0.5C up to 4.2V, and CV charging was performed at 0.01C cut. After a 30-minute rest, CC discharge was further performed at 0.5 C up to 3 V, CV discharge was performed at a 0.01 C cut, and a 30-minute rest was performed.
(4) 1.0C charge / discharge step For each all-solid-state secondary battery after the 0.5C charge / discharge step, CC charging was performed at 1.0 C up to 4.2 V, and CV charging was performed at 0.01 C cut. After a 30-minute rest, CC discharge was further performed at 1.0 C up to 3 V, CV discharge was performed at a 0.01 C cut, and a 30-minute rest was performed.

(5) 1.5C charge / discharge step For each all-solid-state secondary battery after the 1.0C charge / discharge step, CC charging was performed at 1.5C up to 4.2V, and CV charging was performed at 0.01C cut. After a 30-minute rest, CC discharge was further performed at 1.5 C up to 3 V, CV discharge was performed at a 0.01 C cut, and a 30-minute rest was performed.
(6) 2.0C charge / discharge step For each all-solid-state secondary battery after the 1.5C charge / discharge step, CC charging was performed at 2.0C up to 4.2V, and CV charging was performed at 0.01C cut. After a 30-minute rest, CC discharge was performed at 2.0 C up to 3 V, CV discharge was performed at a 0.01 C cut, and a 30-minute rest was performed.
(7) 2.5C charge / discharge step For each all-solid-state secondary battery after the 2.0C charge / discharge step, CC charging was performed at 2.5C up to 4.2V, and CV charging was performed at 0.01C cut. After a 30-minute rest, CC discharge was performed at 2.5 C up to 3 V, CV discharge was performed at a 0.01 C cut, and a 30-minute rest was performed.
(8) 3.0C charge / discharge step For each all-solid-state secondary battery after the 2.5C charge / discharge step, CC charging was performed at 3.0C up to 4.2V, and CV charging was performed at 0.01C cut. After a 30-minute rest, CC discharge was performed at 3.0 C up to 3 V, CV discharge was performed at a 0.01 C cut, and a 30-minute rest was performed.

(9) 3.5C charge / discharge step For each all-solid-state secondary battery after the 3.0C charge / discharge step, CC charging was performed at 3.5C up to 4.2V, and CV charging was performed at 0.01C cut. After a 30-minute rest, CC discharge was further performed at 3.5 C up to 3 V, CV discharge was performed at a 0.01 C cut, and a 30-minute rest was performed.
(10) 4.0C charge / discharge step For each all-solid-state secondary battery after the 3.5C charge / discharge step, CC charging was performed at 4.0 C up to 4.2 V, and CV charging was performed at 0.01 C cut. After a 30-minute rest, CC discharge was performed at 4.0 C up to 3 V, CV discharge was performed at a 0.01 C cut, and a 30-minute rest was performed.
(11) 4.5C charge / discharge step For each all-solid-state secondary battery after the 4.0C charge / discharge step, CC charging was performed at 4.5C up to 4.2V, and CV charging was performed at 0.01C cut. After a 30-minute rest, CC discharge was further performed at 4.5 C up to 3 V, CV discharge was performed at a 0.01 C cut, and a 30-minute rest was performed.
(12) 5.0C charge / discharge step For each all-solid-state secondary battery after the 4.5C charge / discharge step was carried out, CC charging was performed at 5.0 C up to 4.2 V, and CV charging was performed at 0.01 C cut. After a 30-minute rest, CC discharge was performed at 5.0 C up to 3 V, CV discharge was performed at a 0.01 C cut, and a 30-minute rest was performed.

(13) 5.5C charge / discharge step For each all-solid-state secondary battery after the 5.0C charge / discharge step, CC charging was performed at 5.5C up to 4.2V, and CV charging was performed at 0.01C cut. After a 30-minute rest, CC discharge was further performed at 5.5 C to 3 V, CV discharge was performed at a 0.01 C cut, and a 30-minute rest was performed.
(14) 6.0C charge / discharge step For each all-solid-state secondary battery after the 5.5C charge / discharge step, CC charging was performed at 6.0 C up to 4.2 V, and CV charging was performed at 0.01 C cut. After a 30-minute rest, CC discharge was further performed at 6.0 C up to 3 V, CV discharge was performed at a 0.01 C cut, and a 30-minute rest was performed.

The charge / discharge curves showing the charge rate results obtained as described above are shown in FIGS. 2 (1) and 3 (comparative example 1).
However, FIG. 2 shows the charge rate results in each charge / discharge step at 0.1C, 1.0C, 2.0C, 4.0C and 6.0C. FIG. 3 shows the charge rate results in each charge / discharge step at 0.1C, 1.0C, 1.5C, 2.0C, 4.0C and 6.0C. The horizontal axis of FIGS. 2 and 3 indicates the capacity Q (mAh).
From the results shown in FIG. 3, the comparative all-solid-state secondary battery of Comparative Example 1 did not cause an internal short circuit under charge / discharge conditions up to 1.0 C, but was internal under high-rate charge / discharge conditions of 1.5 C or higher. It can be seen that a short circuit has occurred. On the other hand, as shown in FIG. 2, the all-solid-state secondary battery of Example 1 is provided with a solid electrolyte layer thinned to 20 μm, and even under a high-rate charge / discharge condition of 6.0 C. The occurrence of internal short circuit can be effectively suppressed. This is because the lithium metal generated by charging reacts with the solid compound contained in the solid electrolyte layer, which suppresses the growth of dendrite and effectively prevents it from reaching the positive electrode active material layer. it is conceivable that.

[Example 2]
In the method for manufacturing the all-solid-state secondary battery of Example 1, the same as the method for manufacturing the all-solid-state secondary battery of Example 1 except that each sheet is manufactured and each sheet is laminated by the roll-to-roll method. The all-solid-state secondary battery of Example 2 was manufactured. When the charge rate test was performed on the manufactured all-solid-state secondary battery in the same manner as in Example 1, the same results as in Example 1 could be obtained, and it can be sufficiently applied to a continuous manufacturing method. I understand.

1 Negative electrode current collector 2 Negative electrode active material layer 3 Solid electrolyte layer 4 Positive electrode active material layer 5 Positive electrode current collector 6 Operating part 10 All-solid-state secondary battery

Claims (7)

A solid electrolyte layer for an all-solid secondary battery containing a sulfide-based inorganic solid electrolyte having lithium ion conductivity and a solid compound capable of reacting with a lithium metal. The solid electrolyte layer for a solid secondary battery according to claim 1, wherein the solid compound is an inorganic oxide. The solid for a solid secondary battery according to claim 1 or 2, wherein the solid compound contains at least one metal element selected from the group consisting of Ti, V, Cr, Mn, Fe, Co, Ni and Cu. Electrolyte layer. The solid electrolyte layer for a solid secondary battery according to any one of claims 1 to 3, wherein the solid compound is an oxide containing each element of Al, Ti, P and Si. The solid electrolyte layer for a solid secondary battery according to any one of claims 1 to 4, wherein the solid compound is represented by the following composition formula.
Composition formula: Li _{(1 + x + y)} Al _x Ti _(2-x) Si _y P _(3-y) O ₁₂
However, x and y are each more than 0 and less than 1.0. The solid electrolyte layer for a solid secondary battery according to claim 5, wherein a part of Ti is substituted with Ge in the composition formula. An all-solid-state secondary battery comprising the solid electrolyte layer for a solid-state secondary battery according to any one of claims 1 to 6.

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