JP6948474B2 - Negative electrode sheet for all-solid-state secondary batteries and all-solid-state secondary batteries - Google Patents

Description

The present invention relates to an all-solid-state secondary battery and a negative electrode sheet for an all-solid-state secondary battery.

A lithium ion secondary battery is a storage battery having a negative electrode, a positive electrode, and an electrolyte sandwiched between the negative electrode and the positive electrode, and capable of charging and discharging by reciprocating lithium ions between the two electrodes. Conventionally, an organic electrolyte has been used as an electrolyte in a lithium ion secondary battery. However, the organic electrolyte is liable to leak, and there is a risk of short-circuiting and ignition inside the battery due to overcharging or overdischarging, and further improvement in safety and reliability is required.
Under such circumstances, an all-solid-state secondary battery using an inorganic solid electrolyte instead of the organic electrolyte has attracted attention. In an all-solid-state secondary battery, the negative electrode, electrolyte, and positive electrode are all made of solid, which can greatly improve the safety and reliability of batteries using organic electrolytes, and can also extend the life of the battery. It is said that Further, the all-solid-state secondary battery can have a laminated 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 various electronic devices, electric vehicles, large storage batteries, and the like.

The basic layer structure of an all-solid-state secondary battery is a laminated structure consisting of a positive electrode layer, a solid electrolyte layer, and a negative electrode layer. The positive electrode of an all-solid secondary battery generally has a structure in which a positive electrode current collector layer made of a metal foil and a positive electrode active material layer are laminated, and the positive electrode active material layer is in contact with a solid electrolyte layer. Similarly, the negative electrode also has a structure in which a negative electrode current collector layer made of a metal foil and a negative electrode active material layer are laminated, and the negative electrode active material layer is in contact with a solid electrolyte layer.
For the positive electrode active material layer of the all-solid-state secondary battery, a material capable of inserting and releasing metal ions (typically lithium ions) belonging to Group 1 or Group 2 of the periodic table is used. When charging the battery, electrons flow from the positive electrode side to the negative electrode side in the external circuit connecting the positive electrode and the negative electrode, and along with this, the above metal ions are released from the positive electrode active material to the negative electrode side, and these metal ions are discharged to the negative electrode side. Inserted into the active material. The negative electrode active material expands due to the insertion of metal ions, and its volume increases.
On the other hand, in order to eliminate the potential difference caused by charging during discharging, electrons flow from the negative electrode side to the positive electrode side in the external circuit. Along with this, metal ions are released from the negative electrode active material to the positive electrode side, and the released metal ions are inserted into the positive electrode active material, combined with electrons, and reduced to the original state. The negative electrode active material contracts due to the release of metal ions, and the volume decreases (returns to the volume before the metal ions were inserted).

Patent Document 1 has a problem that, in a non-aqueous electrolyte battery, a current tends to concentrate in the vicinity of the outer peripheral edge of each active material when the battery is charged and discharged, and this current concentration causes an in-plane distribution in the volume change of the active material. Have been described. More specifically, since the volume change in the vicinity of the outer peripheral edge of the active material layer during charging / discharging of the battery is larger than that in the central portion, each in the vicinity of the outer peripheral edge of each active material layer as the battery is charged / discharged. A problem has been raised in which good bonding between the active material layer and the solid electrolyte layer cannot be maintained, and the discharge capacity is significantly reduced.

Japanese Unexamined Patent Publication No. 2013-16280

As described above, the negative electrode active material expands by inserting metal ions during charging, and releases metal ions and contracts during discharging. That is, the volume change due to charging / discharging is large. This volume change becomes larger as the negative electrode active material has a higher occlusion capacity of metal ions.
When the negative electrode active material expands during charging, the solid electrolyte existing around it is pushed outward. On the other hand, even if the negative electrode active material shrinks and returns to the original state during discharge, the pushed solid electrolyte does not easily follow the shrinkage of the negative electrode active material. That is, a void is generated between the negative electrode active material constituting the negative electrode active material layer and the solid electrolyte, the conduction path is interrupted, and the internal resistance increases. In order to suppress the generation of this void, the all-solid-state secondary battery is generally used by being enclosed in a housing or the like with a high restraining pressure. However, this high-pressure encapsulation hinders the miniaturization and weight reduction of the all-solid-state secondary battery.
The present invention is an all-solid-state secondary battery in which voids are unlikely to occur in the negative electrode active material layer due to expansion and contraction of the negative electrode active material and an increase in internal resistance due to repeated charging and discharging can be sufficiently suppressed, and the all-solid-state secondary battery. An object of the present invention is to provide a negative electrode sheet suitable as a constituent material of a next battery. Another object of the present invention is to provide an electronic device and an electric vehicle having the all-solid-state secondary battery.

The above problems have been solved by the following means.
[1]
An all-solid-state secondary battery having a laminated structure in which a negative electrode active material layer, a solid electrolyte layer, and a positive electrode active material layer are laminated in this order.
The negative electrode active material layer has a solid particle region X containing a negative electrode active material and an inorganic solid electrolyte, and a polymer region Y formed of a polymer having a tensile elastic modulus of 700 MPa or less.
The solid particle region X and the polymer region Y are arranged in the negative electrode active material layer in the laminating direction of the laminated structure and also in one direction perpendicular to the laminating direction.
In the cross section of the negative electrode active material layer perpendicular to one direction perpendicular to the stacking direction, the solid particle region X and the polymer region Y are alternately arranged in contact with each other. An all-solid-state secondary battery in which the relationship between the widths of both the solid particle region X and the polymer region Y adjacent to each other satisfies the following equation.
0.01 ≤ Y ^w / X ^w ≤ 1.00
X ^w : Width of solid particle region X Y ^w : Width of polymer region Y [2]
The all-solid-state secondary battery according to [1], wherein the solid particle region X contains a particulate binder.
[3]
The all-solid-state secondary battery according to [1] or [2], wherein the negative electrode active material is a silicon-based negative electrode active material.
[4]
The all-solid-state secondary battery according to any one of [1] to [3], wherein the inorganic solid electrolyte is a sulfide-based inorganic solid electrolyte.
[5]
The all-solid-state secondary battery according to any one of [1] to [4], wherein the polymer having a tensile elastic modulus of 700 MPa or less is an elastomer.
[6]
An electronic device having the all-solid-state secondary battery according to any one of [1] to [5].
[7]
An electric vehicle having an all-solid-state secondary battery according to any one of [1] to [5].
[8]
A negative electrode sheet for an all-solid-state secondary battery having a negative electrode active material layer.
The negative electrode active material layer has a solid particle region X containing a negative electrode active material and an inorganic solid electrolyte, and a polymer region Y formed of a polymer having a tensile elastic modulus of 700 MPa or less.
The solid particle region X and the polymer region Y are arranged in the negative electrode active material layer in a direction perpendicular to the surface of the negative electrode active material layer and also in one direction parallel to the surface of the negative electrode active material layer. Arranged in
In a cross section of the negative electrode active material layer parallel to the surface of the negative electrode active material layer and perpendicular to one direction, the solid particle regions X and the polymer regions Y are alternately arranged in contact with each other. A negative electrode sheet for an all-solid-state secondary battery in which the relationship between the widths of both the solid particle region X and the polymer region Y adjacent to each other in the cross section satisfies the following formula.
0.01 ≤ Y ^w / X ^w ≤ 1.00
X ^w : Width of solid particle region X Y ^w : Width of polymer region Y

In the description of 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 all-solid-state secondary battery of the present invention, voids are less likely to occur in the negative electrode active material layer even due to expansion and contraction of the negative electrode active material, and an increase in internal resistance due to repeated charging and discharging can be sufficiently suppressed. In the electronic device and the electric vehicle of the present invention, the increase in internal resistance of the all-solid-state secondary battery contained therein due to repeated charging and discharging is suppressed, and the life of the battery is extended. The negative electrode sheet for an all-solid-state secondary battery of the present invention is suitable as a material for forming a negative electrode layer of the all-solid-state secondary battery of the present invention.

FIG. 1 is a vertical cross-sectional view schematically showing a basic laminated structure of an all-solid-state secondary battery. FIG. 2 is a perspective view schematically showing the configuration of the negative electrode active material layer of the all-solid-state secondary battery of the present invention. FIG. 3 is a cross-sectional view taken along the ABCD surface shown in FIG.

Preferred embodiments of the all-solid-state secondary battery of the present invention will be described, but the present invention is not limited to these embodiments except as specified in the present invention.

[All-solid-state secondary battery]
The all-solid-state secondary battery of the present invention has a laminated structure in which a negative electrode active material layer, a solid electrolyte layer, and a positive electrode active material layer are laminated in this order. FIG. 1 shows an example of a laminated structure of each functional layer in the all-solid-state secondary battery of the present invention. FIG. 1 is a cross-sectional view showing a schematic representation of an all-solid-state secondary battery, and the description of the housing and the like is omitted. The all-solid secondary battery 101 has a negative electrode current collector layer 11, a negative electrode active material layer 12, a solid electrolyte layer 13, a positive electrode active material layer 14, and a positive electrode current collector layer 15 in this order when viewed from the negative electrode side. Adjacent layers are in contact with each other. 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 ions (Li ⁺ ) accumulated in the negative electrode are returned to the positive electrode side, and electrons are supplied to the operating portion 16. In the illustrated example, a light bulb is used as a model for the operating portion 16, and the light bulb is turned on by electric discharge.
Although FIG. 1 shows a laminated structure of five layers including a negative electrode current collector layer 11, a negative electrode active material layer 12, a solid electrolyte layer 13, a positive electrode active material layer 14, and a positive electrode current collector layer 15. The all-solid-state secondary battery of the present invention is not limited to this form. For example, from a laminate in which a positive electrode active material layer, a solid electrolyte layer, and a negative electrode active material layer are laminated in this order, and a current collector layer arranged in contact with the positive electrode active material layer or the negative electrode active material layer of the laminated body. An all-solid secondary battery (monopolar) consisting of multiple units in which the laminated structure is one unit and the units are stacked on a current collector such as a metal foil so that the current collector layers do not come into contact with each other. An all-solid secondary battery having a type or bipolar laminated structure) is also a preferred form of the all-solid secondary battery of the present invention. In this case, if at least one of the plurality of negative electrode active material layers has the structure of the negative electrode active material layer specified in the present invention, the all-solid-state secondary battery of the present invention is used. In an all-solid-state secondary battery having a monopolar type or bipolar type laminated structure, it is preferable that all the negative electrode active material layers have the structure of the negative electrode active material layer specified in the present invention.

<Negative electrode active material layer>
In the all-solid-state secondary battery of the present invention, the negative electrode active material layer has a solid particle region X (hereinafter, also simply referred to as “region X”) containing a negative electrode active material and an inorganic solid electrolyte, and a tensile elasticity of 700 MPa or less. It has a polymer region Y (hereinafter, also simply referred to as “region Y”). Regions X and Y are alternately and adjacent to each other in the negative electrode active material layer. The arrangement of the area X and the area Y will be described with reference to FIG.
FIG. 2 is a perspective view showing one form of a negative electrode active material layer constituting the all-solid-state secondary battery of the present invention shown in FIG. The regions X (1a, 1b, 1c) and the regions Y (2a, 2b) are both arranged in the negative electrode active material layer in the stacking direction (L direction) in the laminated structure of the all-solid-state secondary battery shown in FIG. (Penetrating in the stacking direction (L direction)). As a result, it is possible to more reliably secure the conduction path of the ion moving in the L direction in the region X. Further, both the region X and the region Y are arranged side by side in the depth direction (Z direction) of the negative electrode active material layer (the region X also penetrates in the depth direction (Z direction)). As a result, the expansion of the negative electrode active material in the region X during charging can be absorbed more reliably. As shown in FIG. 2, the regions X and Y are alternately arranged so as to be in contact with each other.
As described above, in the negative electrode active material layer constituting the all-solid-state secondary battery of the present invention, the regions X and Y are arranged in the negative electrode active material layer in the stacking direction (L direction) of each functional layer, and The structure is arranged side by side in one direction (Z direction in FIG. 2) perpendicular to the stacking direction. Further, in a cross section (for example, ABCD surface) of the negative electrode active material layer perpendicular to one direction (Z direction in FIG. 2) perpendicular to the stacking direction (L direction) of each functional layer, the solid particle region X And the polymer region Y are alternately arranged in contact with each other.
Although FIG. 2 shows the shape of the negative electrode active material layer as a rectangular parallelepiped, the present invention is not limited to this form, and can be a desired shape such as a cylindrical shape.

A cross section perpendicular to the Z direction of FIG. 2 is shown in FIG. In the cross section shown in FIG. 3, the relationship between the widths of the solid particle region X and the polymer region Y adjacent to each other ^{satisfies 0.01 ≦ Y w} / X ^w ≦ 1.00. Here, X ^w is the width of the solid particle region X (1a, 1b, 1c) in ^{the cross section of FIG. 3, and Y w} is the width of the polymer region Y (2a, 2b) in the cross section of FIG. X ^w and Y ^{w satisfy 0.01 ≤ Y w} / X ^w ≤ 1.00 in all the cross sections perpendicular to the Z direction (the ABCD plane and all the cross sections parallel to the ABCD plane). Further, although there are usually a plurality of combinations (pairs) of the solid particle region X and the polymer region Y adjacent to each other (in FIGS. 2 and 3, 4 pairs of 1a and 2a, 2a and 1b, 1b and 2b, 2b and 1c). ^{, 0.01 ≦ Y w} / X ^w ≦ 1.00 is satisfied in all combinations of the solid particle region X and the polymer region Y adjacent to each other.
X ^w and Y ^w are determined as follows.
It is assumed that the cross section of the negative electrode active material layer perpendicular to the Z direction (cross section shown in FIG. 3) is divided into six equal parts in the L direction, and this cross section is divided into six regions. At this time, there are five boundary portions that divide each of the six regions. The widths of both the solid particle region X and the polymer region Y were measured for these five boundary portions, and the average of the five measured values obtained for each of the solid particle region X and the polymer region Y was defined as X ^w . Let Y ^w . This measurement can be performed by observing the cross section with a scanning electron microscope and measuring the width of the five boundary portions.
The relationship between X ^w and Y ^{w preferably satisfies 0.02 ≦ Y w} / X ^w ≦ 0.80, and more preferably 0.02 ≦ Y ^w / X ^w ≦ 0.70.

By configuring the negative electrode active material layer in this way, the soft polymer region having a tensile elasticity of 700 MPa or less effectively absorbs the expansion of the negative electrode active material layer during charging and shrinks the negative electrode active material during discharging. Since the polymer region returns to its original shape following the above, voids are unlikely to occur between the solid particles constituting the negative electrode active material layer. As a result, it is possible to sufficiently suppress an increase in internal resistance due to repeated charging and discharging. Further, since the size of the polymer region is limited, a sufficient discharge capacity can be secured.
The negative electrode active material layer usually has a plurality of regions X divided by the region Y, and also has a plurality of regions Y divided by the region X, as shown in FIGS. 2 and 3. These plurality of regions X may have the same size and composition as each other, or may differ from each other. Also, the plurality of regions Y may be the same in size and composition from each other, or may be different from each other. It is preferable that the plurality of regions X have the same size and composition as each other. Similarly, the plurality of regions Y preferably have the same size and composition as each other.
As shown in FIGS. 2 and 3, the negative electrode active material layer is arranged so that the solid particle region X and the polymer region Y are alternately arranged in a cross section perpendicular to the Z direction. The outermost region in this alternating arrangement is preferably the solid particle region X.

In the negative electrode active material layer, ^{the sizes of X w} and Y ^w are not particularly limited as long as the above relational expression is satisfied. For example, X ^w can be 0.01 to 1000 mm, preferably 0.1 to 100 mm, more preferably 1 to 50 mm.

Subsequently, the constituent materials of the negative electrode active material layer will be described.

[Area X]
In the negative electrode active material layer constituting the all-solid-state secondary battery of the present invention, the region X contains a negative electrode active material and an inorganic solid electrolyte as solid particles.

(Negative electrode active material)
The negative electrode active material is an active material capable of inserting and releasing ions of a metal belonging to Group 1 or Group 2 of the periodic table.
The negative electrode active material is preferably one capable of reversibly inserting and / or releasing lithium ions. The material is not particularly limited as long as it has the above-mentioned characteristics, and is a carbonaceous material, an oxide of a metal or a semi-metallic element (including a composite oxide), a simple lithium substance, a lithium alloy, or an alloy with lithium. Examples thereof include active materials that can be converted (form an alloy with lithium). Among them, from the viewpoint of reliability, a carbonaceous material, an oxide of a metalloid element, a metal composite oxide, or a simple substance of lithium is preferable. An active material that can be alloyed with lithium is preferable in that the capacity of the all-solid-state secondary battery can be increased.

The carbonaceous material used as the negative electrode active material is a material substantially composed of carbon. For example, various synthesis of petroleum pitch, carbon black such as acetylene black (AB), graphite (artificial graphite such as natural graphite and vapor-grown graphite), and PAN (polyacrylonitrile) -based resin or furfuryl alcohol resin. A carbonaceous material obtained by firing a resin can be mentioned. Furthermore, various carbon fibers such as PAN-based carbon fibers, cellulose-based carbon fibers, pitch-based carbon fibers, vapor-grown carbon fibers, dehydrated PVA (polypoly alcohol) -based carbon fibers, lignin carbon fibers, glassy carbon fibers, and activated carbon fibers. Kind, mesophase microspheres, graphite whisker, flat plate graphite and the like can also be mentioned.

These carbonaceous materials can also be divided into non-graphitizable carbonaceous materials (also referred to as hard carbon) and graphite-based carbonaceous materials depending on the degree of graphitization. Further, the carbonaceous material preferably has the plane spacing or density and the size of crystallites described in JP-A-62-22066, JP-A-2-6856, and JP-A-3-45473. The carbonaceous material does not have to be a single material, and a mixture of natural graphite and artificial graphite described in JP-A-5-90844, graphite having a coating layer described in JP-A-6-4516, and the like should be used. You can also.
As the carbonaceous material, hard carbon or graphite is preferably used, and graphite is more preferably used.

The metal or semi-metal element oxide applied as the negative electrode active material is not particularly limited as long as it is an oxide capable of storing and releasing lithium, and is a composite of a metal element oxide (metal oxide) and a metal element. Examples thereof include oxides or composite oxides of metal elements and semi-metal elements (collectively referred to as metal composite oxides) and oxides of semi-metal elements (semi-metal oxides). As these oxides, amorphous oxides are preferable, and chalcogenite, which is a reaction product of a metal element and an element of Group 16 of the periodic table, is also preferable. In the present invention, the metalloid element means an element exhibiting properties intermediate between a metal element and a non-metalloid element, and usually contains six elements of boron, silicon, germanium, arsenic, antimony and tellurium, and further selenium. , Polonium and Astatin. Further, "amorphous" means an X-ray diffraction method using CuKα rays, which has a broad scattering band having an apex in a region of 20 ° to 40 ° in 2θ value, and a crystalline diffraction line is used. You may have. The strongest intensity of the crystalline diffraction lines found at the 2θ value of 40 ° to 70 ° is 100 times or less the diffraction line intensity at the apex of the broad scattering band seen at the 2θ value of 20 ° to 40 °. It is preferable that it is 5 times or less, and it is particularly preferable that it does not have a crystalline diffraction line.

Among the compound group consisting of the amorphous oxide and the chalcogenide, the amorphous oxide of the metalloid element or the chalcogenide is more preferable, and the elements of the groups 13 (IIIB) to 15 (VB) of the periodic table (for example). , Al, Ga, Si, Sn, Ge, Pb, Sb and Bi) alone or a combination of two or more (composite) oxides, or chalcogenides are particularly preferred. Specific examples of preferable amorphous oxides and chalcogenides include, for example, Ga ₂ O ₃ , SiO, GeO, SnO, SnO ₂ , PbO, PbO ₂ , Pb ₂ O ₃ , Pb ₂ O ₄ , Pb ₃ O ₄ , Sb ₂ O ₃ , Sb ₂ O ₄ , Sb ₂ O ₈ Bi ₂ O ₃ , Sb ₂ O ₈ Si ₂ O ₃ , Sb ₂ O ₅ , Bi ₂ O ₃ , Bi ₂ O ₄ , SnSiO ₃ , GeS, SnS, SnS ₂ , PbS, PbS ₂ , Sb ₂ S ₃ , Sb ₂ S ₅ or SnSi _{S 3} are preferably mentioned.

Examples of the negative electrode active material that can be used in combination with the amorphous oxide negative electrode active material centering on Sn, Si, and Ge include a carbonaceous material capable of occluding and / or releasing lithium ions or lithium metal, lithium alone, and lithium. An active material that can be alloyed with an alloy or lithium is preferably used.

It is preferable that the oxide of a metal or a metalloid element, particularly a metal (composite) oxide and the chalcogenide, contains at least one of titanium and lithium as a constituent component from the viewpoint of high current density charge / discharge characteristics. Examples of the lithium-containing metal composite oxide (lithium composite metal oxide) include a composite oxide of lithium oxide and the metal (composite) oxide or the chalcogenide, and more specifically, Li ₂ SnO _2. Can be mentioned.
It is also preferable that the negative electrode active material, for example, a metal oxide, contains a titanium atom (titanium oxide). Specifically, Li ₄ Ti ₅ O ₁₂ (lithium titanate [LTO]) has excellent rapid charge / discharge characteristics because the volume fluctuation during storage and release of lithium ions is small, and deterioration of electrodes is suppressed and lithium ion secondary This is preferable in that the battery life can be improved.

The lithium alloy as the negative electrode active material is not particularly limited as long as it is an alloy usually used as the negative electrode active material of the secondary battery, and examples thereof include a lithium aluminum alloy.

The active material that can be alloyed with lithium is not particularly limited as long as it is usually used as the negative electrode active material of the secondary battery, and for example, each metal or metalloid such as Sn, Si, Al and In, and further. , Silicon-based negative electrode active material (for example, Si or SiO) containing Si element as a constituent element can be mentioned. SiO itself can be used as a negative electrode active material (metalloid oxide), and since Si is generated by the operation of an all-solid-state secondary battery, an active material that can be alloyed with lithium (a precursor material thereof). ) Can be used. Among them, a silicon-based negative electrode active material is preferable, and Si is more preferable.
As described above, the negative electrode active material layer formed by using the active material that can be alloyed with lithium has a large expansion and contraction due to charging and discharging. On the other hand, in general, more Li ions can be occluded as compared with the negative electrode active material layer (carbon negative electrode) formed by using a carbon-based material such as graphite and acetylene black. That is, the amount of Li ions occluded per unit mass increases. Therefore, there is an advantage that the battery capacity can be increased and the battery drive time can be lengthened.

In the present invention, the chemical formula of the compound obtained by the firing method can be calculated from the inductively coupled plasma (ICP) emission spectroscopic analysis method as a measuring method and the mass difference of the powder before and after firing as a simple method.

-Coating of negative electrode active material-
The surface of the negative electrode active material may be surface-coated with another metal oxide. Examples of the surface coating agent include metal oxides containing Ti, Nb, Ta, W, Zr, Al, Si or Li. Specific examples thereof include spinel titanate, tantalum oxide, niobate oxide, lithium niobate compound and the like. Specifically, Li ₄ Ti ₅ O ₁₂ , Li ₂ Ti ₂ O ₅ and LiTaO ₃ , LiNbO ₃ , LiAlO ₂ , Li ₂ ZrO ₃ , Li ₂ WO ₄ , Li ₂ TIO ₃ , Li ₂ B ₄ O ₇ , Li ₃ PO ₄ , Li ₂ MoO ₄ , Li ₃ BO ₃ , LiBO ₂ , Li ₂ CO ₃ , Li ₂ SiO ₃ , SiO ₂ , TiO ₂ , ZrO ₂ , Al ₂ O ₃ , B ₂ O _{3, and the} like.
Further, the surface of the electrode containing the negative electrode active material may be surface-treated with sulfur or phosphorus.
Further, the particle surface of the negative electrode active material may be surface-treated with active light rays or an active gas (plasma or the like) before and after the surface coating.

The shape of the negative electrode active material is not particularly limited, but is preferably in the form of particles. The average particle size of the negative electrode active material is not particularly limited, but is preferably 0.1 to 60 μm. The average particle size of the negative electrode active material particles can be measured in the same manner as the average particle size of the inorganic solid electrolyte. A normal crusher or classifier is used to adjust the negative electrode active material to a predetermined particle size. For example, a mortar, a ball mill, a sand mill, a vibrating ball mill, a satellite ball mill, a planetary ball mill, a swirling airflow type jet mill, a sieve, or the like is preferably used. At the time of pulverization, wet pulverization in which an organic solvent such as water or methanol coexists can also be performed. It is preferable to perform classification in order to obtain a desired particle size. The classification is not particularly limited, and can be performed using a sieve, a wind power classifier, or the like. Both dry and wet classifications can be used.

The region X may contain one or more negative electrode active materials.

The content of the negative electrode active material in the region X is not particularly limited, and is preferably 10 to 90% by mass, more preferably 20 to 85% by mass, more preferably 30 to 80% by mass, and 40. It is more preferably ~ 75% by mass.

(Inorganic solid electrolyte)
The negative electrode active material layer of the present invention contains an inorganic solid electrolyte in region X.
In the present invention, the inorganic solid electrolyte is an inorganic solid electrolyte, and the solid electrolyte is a solid electrolyte capable of transferring ions inside the solid electrolyte. Since it does not contain organic substances as the main ionic conductive material, it is an organic solid electrolyte (polyelectrolyte represented by polyethylene oxide (PEO), organic such as lithium bis (trifluoromethanesulfonyl) imide (LiTFSI)). It is clearly distinguished from electrolyte salts). Further, since the inorganic solid electrolyte is a solid in a steady state, it is usually not dissociated or liberated into cations and anions. _{In this respect, it is clearly distinguished from the electrolyte or inorganic electrolyte salts (LiPF 6} , LiBF ₄ , Lithium bis (fluorosulfonyl) imide (LiFSI), LiCl, etc.) that are dissociated or liberated into cations and anions in the polymer. Will be done. The inorganic solid electrolyte is not particularly limited as long as it has the ionic conductivity of a metal belonging to Group 1 or Group 2 of the periodic table, and is generally one having no electron conductivity. When the all-solid-state secondary battery of the present invention is a lithium-ion battery, the inorganic solid electrolyte preferably has lithium ion ionic conductivity.

As the inorganic solid electrolyte, a solid electrolyte material usually used for an all-solid secondary battery can be appropriately selected and used. Typical examples of the inorganic solid electrolyte include (i) a sulfide-based inorganic solid electrolyte and (ii) an oxide-based inorganic solid electrolyte. In the present invention, a sulfide-based inorganic solid electrolyte is preferably used from the viewpoint of being able to form a better interface between the active material and the inorganic solid electrolyte.

(I) Sulfide-based inorganic solid electrolyte The sulfide-based inorganic solid electrolyte contains a sulfur atom, has ionic conductivity of a metal belonging to Group 1 or Group 2 of the Periodic Table, and is electronically insulated. Those having sex are preferable. The sulfide-based inorganic solid electrolyte preferably contains at least Li, S and P as elements and has lithium ion conductivity, but other than Li, S and P may be used depending on the purpose or case. It may contain elements.

Examples of the sulfide-based inorganic solid electrolyte include a lithium ion conductive inorganic solid electrolyte satisfying the composition represented by the following formula (1).

L _a1 M _b1 P _c1 S _d1 A _e1 (1)

In the formula, L represents an element selected from Li, Na and K, with Li being preferred. M represents an element selected from B, Zn, Sn, Si, Cu, Ga, Sb, Al and Ge. A represents an element selected from I, Br, Cl and F. a1 to e1 indicate the composition ratio of each element, and a1: b1: c1: d1: e1 satisfy 1 to 12:00 to 5: 1: 2 to 12:00 to 10. a1 is preferably 1 to 9, more preferably 1.5 to 7.5. b1 is preferably 0 to 3, more preferably 0 to 1. d1 is preferably 2.5 to 10 and more preferably 3.0 to 8.5. e1 is preferably 0 to 5, more preferably 0 to 3.

The composition ratio of each element can be controlled by adjusting the blending amount of the raw material compound when producing the sulfide-based inorganic solid electrolyte as described below.

The sulfide-based inorganic solid electrolyte may be amorphous (glass) or crystallized (glass-ceramic), or only a part thereof may be crystallized. For example, Li-PS-based glass containing Li, P and S, or Li-PS-based glass ceramics containing Li, P and S can be used.
Sulfide-based inorganic solid electrolytes include, for example, lithium sulfide (Li ₂ S), phosphorus sulfide (for example, diphosphorus pentasulfide (P ₂ S ₅ )), simple phosphorus, simple sulfur, sodium sulfide, hydrogen sulfide, and lithium halide (eg, lithium halide). It can be produced by the reaction of at least two or more raw materials in sulfides of LiI, LiBr, LiCl) and the element represented by M (for example, SiS ₂ , SnS, GeS _2).

The ratio of _{Li 2} S to P ₂ S _{5 in} Li-PS-based glass and Li-PS-based glass ceramics is the molar ratio of _{Li 2} S: P ₂ S _{5, preferably 60:40 to} It is 90:10, more preferably 68:32 to 78:22. By _{setting the ratio of Li 2} S and P ₂ S ₅ in this range, the lithium ion conductivity can be made high. Specifically, the lithium ion conductivity can be preferably 1 × 10 ^-4 S / cm or more, and more preferably 1 × 10 ^-3 S / cm or more. There is no particular upper limit, but it is practical that it is ^{1 × 10 -1 S / cm or less.}

As an example of a specific sulfide-based inorganic solid electrolyte, a combination example of raw materials is shown below. For _{example, Li 2 S-P 2 S} 5, Li 2 S-P 2 S 5 -LiCl, Li 2 S-P 2 S 5 -H 2 S, Li 2 S-P 2 S 5 -H 2 S-LiCl, Li ₂ S-LiI-P ₂ S ₅ , Li ₂ S-LiI-Li ₂ O-P ₂ S ₅ , Li ₂ S-LiBr-P ₂ S ₅ , Li ₂ S-Li ₂ O-P ₂ S ₅ , Li ₂ S-Li ₃ PO _4- P ₂ S ₅ , Li ₂ S-P ₂ S _5- P ₂ O ₅ , Li ₂ S-P ₂ S _5- SiS ₂ , Li ₂ S-P ₂ S _5- SiS _2- LiCl, Li ₂ S-P ₂ S _5- SnS, Li ₂ S-P ₂ S _5- Al ₂ S ₃ , Li ₂ S-GeS ₂ , Li ₂ S-GeS _2- ZnS, Li ₂ S-Ga ₂ S ₃ , Li ₂ S-GeS _2- Ga ₂ S ₃ , Li ₂ S-GeS _2- P ₂ S ₅ , Li ₂ S-GeS _2- Sb ₂ S ₅ , Li ₂ S-GeS _2- Al ₂ S ₃ , Li ₂ S-SiS ₂ , Li ₂ S-SiS ₅ , Li ₂ S-Al ₂ S ₃ , Li ₂ S-SiS _2- Al ₂ S ₃ , Li ₂ S-SiS _2- P ₂ S ₅ , Li ₂ S-SiS _2- P ₂ S _5- LiI, Li ₂ S-SiS _2- LiI, Li ₂ S-SiS _{2 -Li 4} SiO ₄ , Li ₂ S-SiS _{2 -Li 3} PO ₄ , Li ₁₀ GeP ₂ such as S _12, and the like. However, the mixing ratio of each raw material does not matter. As a method for synthesizing a sulfide-based inorganic solid electrolyte material using such a raw material composition, for example, an amorphization method can be mentioned. Examples of the amorphization method include a mechanical milling method, a solution method and a melt quenching method. This is because processing at room temperature is possible and the manufacturing process can be simplified.

(Ii) Oxide-based inorganic solid electrolyte The oxide-based inorganic solid electrolyte contains an oxygen atom, has ionic conductivity of a metal belonging to Group 1 or Group 2 of the Periodic Table, and is electronically insulated. Those having sex are preferable.
The oxide-based inorganic solid electrolyte preferably has an ionic conductivity of 1 × 10 ^-6 S / cm or more, more preferably 5 × 10 ^-6 S / cm or more, and 1 × 10 ^-5 S / cm or more. It is particularly preferable that it is / cm or more. The upper limit is not particularly limited, but it is practical that it is ^{1 × 10 -1 S / cm or less.}

As a specific example of the compound, for example, Li _xa La _ya TiO ₃ [xa satisfies 0.3 ≦ xa ≦ 0.7, and ya satisfies 0.3 ≦ ya ≦ 0.7. (LLT); Li _{xb Layb} Zr _zb M ^bb _{mb Onb} (M ^bb is one or more elements selected from Al, Mg, Ca, Sr, V, Nb, Ta, Ti, Ge, In and Sn. Xb satisfies 5 ≦ xb ≦ 10, yb satisfies 1 ≦ yb ≦ 4, zb satisfies 1 ≦ zb ≦ 4, mb satisfies 0 ≦ mb ≦ 2, and nb satisfies 5 ≦ nb ≦ 20. Satisfy.); Li _{xc Byc} M ^cc _{zc Onc} (M ^cc is one or more elements selected from C, S, Al, Si, Ga, Ge, In and Sn. Xc is 0 <xc ≦ 5 , Yc satisfies 0 <yc ≦ 1, zc satisfies 0 <zc ≦ 1, nc satisfies 0 <nc ≦ 6); Li _xd (Al, Ga) _yd (Ti, Ge) _zd Si. _ad P _md O _nd (xd satisfies 1 ≦ xd ≦ 3, yd satisfies 0 ≦ yd ≦ 1, zd satisfies 0 ≦ zd ≦ 2, ad satisfies 0 ≦ ad ≦ 1, md is 1 ≦ met md ≦ 7, nd satisfies _{3 ≦ nd ≦ 13);.} Li (3-2xe) M ee xe D ee O (xe represents a number of 0 to ^{0.1, M ee} divalent ^{.D ee} representing the metal atom represents a combination of halogen atom or two or more halogen _{atoms);. Li xf Si yf O} zf (xf satisfies 1 ≦ xf ≦ 5, yf satisfies 0 <yf ≦ 3 , Zf satisfies 1 ≦ zf ≦ 10); Li _xg S _yg O _zg (xg satisfies 1 ≦ xg ≦ 3, yg satisfies 0 <yg ≦ 2, and zg satisfies 1 ≦ zg ≦ 10. ); Li ₃ BO ₃ ; Li ₃ BO _{3- Li 2} SO ₄ ; Li ₂ O-B ₂ O _3- P ₂ O ₅ ; Li ₂ O-SiO ₂ ; Li ₆ BaLa ₂ Ta ₂ O ₁₂ ; Li ₃ PO _{(4-3 / 2w)} N _{w (w is w <1); Li 3.5} Zn _0.25 GeO ₄ having a LISION (Lithium super ionic controller) type crystal structure _{; La 0.55} having a perovskite type crystal structure Li _0.35 TiO _{3 ; LiTi 2} P ₃ O ₁₂ having a NASICON (Naturium super ionic controller) type crystal structure; Li _{1 + xh + yh} (Al, Ga) _xh (Ti, Ge) _{2-xh Sihy} P _3-yh O ₁₂ (xh satisfies 0 ≦ xh ≦ 1, yh satisfies 0 ≦ yh ≦ 1. _{); Li 7} La ₃ Zr ₂ O ₁₂ (LLZ) having a garnet-type crystal structure and the like can be mentioned.
Phosphorus compounds containing Li, P and O are also desirable. For example, lithium phosphate (Li ₃ PO ₄ ); LiPON in which a part of oxygen of lithium phosphate is replaced with nitrogen; LiPOD ¹ (D ¹ is preferably Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zr, Nb, Mo, Ru, Ag, Ta, W, Pt and one or more elements selected from Au) and the like.
Further, LiA ¹ ON (A ¹ is one or more elements selected from Si, B, Ge, Al, C and Ga) and the like can also be preferably used.

The inorganic solid electrolyte is preferably particles. In this case, the average particle size (volume average particle size) of the inorganic solid electrolyte is not particularly limited, but is preferably 0.01 μm or more, and more preferably 0.1 μm or more. The upper limit is preferably 100 μm or less, and more preferably 50 μm or less. The average particle size is measured by the following procedure. Inorganic solid electrolyte particles are prepared by diluting 1% by mass of a dispersion in a 20 mL sample bottle with water (heptane in the case of a water-unstable substance). The diluted dispersed sample is irradiated with 1 kHz ultrasonic waves for 10 minutes, and immediately after that, it is used for the test. Using this dispersion sample, data was captured 50 times using a measurement quartz cell at a temperature of 25 ° C. using a laser diffraction / scattering particle size distribution measuring device LA-920 (trade name, manufactured by HORIBA). Obtain the volume average particle size. For other detailed conditions, etc., refer to the description of JIS Z 8828: 2013 “Particle size analysis-Dynamic light scattering method” as necessary. Five samples are prepared for each level and the average value is adopted.

The content of the inorganic solid electrolyte in the region X can be, for example, 10 to 90% by mass, preferably 15 to 80% by mass, more preferably 20 to 70% by mass, still more preferably 35 to 60% by mass.

(binder)
The negative electrode active material layer of the present invention may have a binder in the region X.
The binder contained in the negative electrode active material layer can be composed of various organic polymer compounds (polymers). The binder enhances the binding property between solid particles such as an inorganic solid electrolyte and an active material, and contributes to the improvement of mechanical strength, ionic conductivity and the like. The organic polymer compound constituting the binder may be in the form of particles or may be in the form of non-particulates. From the viewpoint of further enhancing ionic conductivity, a particulate binder is preferable. The particulate binder has a particle size (volume average particle size) of preferably 10 to 1000 nm, more preferably 20 to 750 nm, further preferably 30 to 500 nm, and even more preferably 50 to 300 nm.

The binder can be composed of, for example, the organic polymer compounds described below.

-Fluororesin-
Examples of the fluororesin include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), and a copolymer of polyvinylidene fluoride and hexafluoropropylene (PVdF-HFP).

-Hydrocarbon-based thermoplastic resin-
Examples of the hydrocarbon-based thermoplastic resin include polyethylene, polypropylene, styrene-butadiene rubber (SBR), hydrogenated styrene-butadiene rubber (HSBR), butylene rubber, acrylonitrile-butadiene rubber, polybutadiene, and polyisoprene.

-(Meta) acrylic resin-
Examples of the (meth) acrylic resin include various (meth) acrylic monomers, (meth) acrylamide monomers, and two or more copolymers of these monomers.
Further, a copolymer (copolymer) with other vinyl-based monomers is also preferably used. For example, a copolymer of methyl (meth) acrylate and styrene, a polymer of methyl (meth) acrylate and acrylonitrile, and a polymer of butyl (meth) acrylate, acrylonitrile and styrene can be mentioned. It is not limited to these. Further, the (meth) acrylic resin may have a constituent component derived from a macromonomer. In the present specification, the copolymer may be either a statistical copolymer or a periodic copolymer, and a random copolymer is preferable.

-Other resins-
Examples of other resins include polyurethane resin, polyurea resin, polyamide resin, polyimide resin, polyester resin, polyether resin, polycarbonate resin, cellulose derivative resin and the like.

When the region X contains a binder, the content of the binder in the region X can be 1 to 20% by mass, preferably 2 to 15% by mass, more preferably 3 to 10% by mass.

Among the above, fluorine-containing resin, hydrocarbon-based thermoplastic resin, (meth) acrylic resin, polyurethane resin, polycarbonate resin and cellulose derivative resin are preferable, and the affinity with the inorganic solid electrolyte is good, and the resin itself A (meth) acrylic resin or a polyurethane resin is particularly preferable because it has good flexibility and can exhibit stronger binding property to solid particles.
Commercially available products can be used as the above-mentioned various resins. It can also be prepared by a conventional method.
The number average molecular weight of the polymer constituting the binder is preferably 1000 to 1000000, more preferably 1000 to 500000, from the viewpoint of improving the binding property between the solid particles.
The organic polymer compound described above is an example, and the binder in the present invention is not limited to these forms.

[Area Y]
In the negative electrode active material layer constituting the all-solid-state secondary battery of the present invention, the region Y is composed of a polymer having a tensile elastic modulus of 700 MPa or less. The region Y can be composed of one kind or two or more kinds of polymers having a tensile elastic modulus of 700 MPa or less. Further, the region Y may include an air region as long as the effect of the present invention is not impaired.

(Polymer with tensile elastic modulus of 700 MPa or less)
A polymer having a tensile elastic modulus of 700 MPa or less (hereinafter, also referred to as “polymer Y”) has soft physical properties and absorbs expansion of the negative electrode active material layer during charging in region X.
The tensile elastic modulus of the polymer Y is not particularly limited as long as it is 700 MPa or less. For example, the elastic modulus of the polymer Y can be 10 to 700 MPa, preferably 20 to 600 MPa, more preferably 30 to 550 MPa, and particularly preferably 50 to 500 MPa.
The polymer Y is preferably an elastomer (a polymer that exhibits rubber elasticity at room temperature (25 ° C.)).
The type of polymer Y is also not particularly limited, and examples thereof include polyurethane-based elastomers, styrene-based elastomers, olefin-based elastomers, vinyl chloride-based elastomers, polyester-based elastomers, polyamide-based elastomers, silicone-based elastomers, and fluorine-based elastomers. ..

-Polyurethane elastomer-
The polyurethane-based elastomer is an elastomer in which the hard segment has a polyurethane structure. Examples of the polyurethane-based elastomer include an elastomer containing a structural unit of a hard segment composed of a low molecular weight glycol and a diisocyanate and a soft segment composed of a polymer (long chain) diol and a diisocyanate.
Examples of the high molecular weight (long chain) diol include polypropylene glycol, polytetramethylene oxide, poly (1,4-butylene adipate), poly (ethylene-1,4-butylene adipate), polycaprolactone, and poly (1,6-he). Xylene carbonate), poly (1,6-hexylene / neopentylene adipate) and the like. The number average molecular weight of the polymer (long chain) diol is preferably 500 or more and less than 10,000.
As the low molecular weight glycol, short chain diols such as ethylene glycol, propylene glycol, 1,4-butanediol and bisphenol A can be used. The number average molecular weight of the short chain diol is preferably 48 or more and less than 500.

-Styrene-based elastomer-
The styrene-based elastomer is an elastomer in which the hard segment has a polystyrene structure. Examples of styrene-based elastomers include styrene-butadiene block copolymer (SBR), hydrogenated styrene-butadiene block copolymer (SEB, styrene-ethylene / butylene block copolymer), and styrene-butadiene-styrene block copolymer. Combined (SBS), hydrogenated styrene-butadiene-styrene block copolymer (SEBS, styrene-ethylene / butylene-styrene block copolymer), styrene-isoprene block copolymer (SIR), hydrogenated styrene-isoprene block Polymers (SEP, styrene-ethylene / propylene block copolymers), styrene-isoprene-styrene block copolymers (SIS), hydrogenated styrene-isoprene-styrene block copolymers (SEPS, styrene-ethylene / propylene-styrene) Block copolymers) and the like, and one or more of these can be used.

-Olefin-based elastomer-
The olefin-based elastomer is a crosslinked or non-crosslinked elastomer having a polyolefin structure. Examples of the olefin-based elastomer include an ethylene-propylene copolymer, an ethylene-1-butene copolymer, an ethylene-α-olefin copolymer, a propylene-1-butene copolymer, and a propylene-α-olefin copolymer. , 1-butene-α-olefin copolymer, propylene-1-butene-ethylene copolymer, propylene-α-olefin-ethylene copolymer, propylene-α-olefin-1-butene copolymer, 1-butene Ethylene-propylene rubber was dispersed in −α-olefin-ethylene copolymer, isoprene rubber (IR), cis-1,4-polybutadiene (BR), chloroprene rubber (CR), butyl rubber (IIR), and polypropylene. Examples thereof include an elastomer and an elastomer in which ethylene-propylene-diene rubber is dispersed in polypropylene, and one or more of these can be used.

-Vinyl chloride elastomer-
A vinyl chloride-based elastomer is an elastomer in which the hard segment has a polyvinyl chloride structure. Examples of the vinyl chloride-based elastomer include polyvinyl chloride having a high degree of polymerization. Further, an elastomer in which the crosslinked portion functions as a hard segment and the linear portion functions as a soft segment by using partially crosslinked polyvinyl chloride can be mentioned.

-Polyester elastomer-
A polyester-based elastomer is an elastomer in which the hard segment has a polyester structure. For example, a block copolymer composed of a high melting point polyester segment (hard segment) described in JP-A-11-92636 and a low melting point polymer segment (soft segment) having a molecular weight of about 400 to 6,000 can be used. Examples of the refractory polyester segment include polybutylene terephthalate (PBT) and the like. Further, examples of the low melting point polymer segment include an amorphous polyether having a glass transition temperature of −70 ° C., for example, polytetramethylene ether glycol (PTMG) and the like.

-Polyamide-based elastomer-
The polyamide-based elastomer is an elastomer in which the hard segment has a polyamide structure. For example, a multi-block copolymer in which the hard segment is polyamide and the soft segment is a polyether or polyester can be mentioned. Examples of the hard segment include polyamides 6, 66, 610, 11, 12 and the like. Examples of the polyether in the soft segment include polyethylene glycol, diol poly (oxytetramethylene) glycol, poly (oxypropylene) glycol and the like, and the polyester includes poly (ethylene adipate) glycol and poly (butylene-1,4-adipate) glycol. And so on.

-Silicone elastomer-
The silicone-based elastomer is an elastomer having an organopolysiloxane structure. A crosslinked structure is introduced into an organopolysiloxane, and for example, polydimethylsiloxane-based, polymethylphenylsiloxane-based, and polydiphenylsiloxane-based elastomers are known. Silicone Specific examples of commercially available silicone-based elastomers include KE series (manufactured by Shin-Etsu Chemical Co., Ltd.), SE series, CY series, and SH series (all manufactured by Toray Dow Corning Silicone Co., Ltd.).

-Fluorine-based elastomer-
The fluoroelastomer is an elastomer in which the hard segment is formed of a fluororesin. Examples of the fluorine-based elastomer include tetrafluoroethylene-ethylene copolymer, tetrafluoroethylene-propylene copolymer, chlorotrifluoroethylene-ethylene copolymer, polyvinylidene fluoride, polyvinyl fluoride, and vinylidene fluoride-hexa. Fluoropropylene copolymer, tetrafluoroethylene-vinylidene fluoride-hexafluoropropylene copolymer, tetrafluoroethylene-vinylidene fluoride-perfluoroalkyl vinyl ether copolymer, tetrafluoroethylene-vinylidene fluoride-propylene copolymer, Examples thereof include a tetrafluoroethylene-vinylidene fluoride-hexafluoropropylene copolymer.

Of these, the polymer Y is preferably a polyurethane-based elastomer.

The tensile modulus of the polymer is measured according to JIS K6251: 2010 "Vulcanized rubber and thermoplastic rubber", and the dumbbell-shaped test piece is measured as No. 1.

<Formation of negative electrode active material layer>
Subsequently, the formation of the negative electrode active material layer will be described.
The formation of the negative electrode active material layer constituting the all-solid-state secondary battery of the present invention is not particularly limited as long as the negative electrode active material layer satisfying the provisions of the present invention can be formed. For example, a region X forming coating liquid (slurry) containing the constituent material of region X and a dispersion medium and a region Y forming coating liquid in which the constituent material (polymer) of region Y is dissolved are prepared, and these coating liquids are used. , Can be applied on a substrate (negative electrode current collector or solid electrolyte layer, that is, a layer in contact with the negative electrode active material layer in an all-solid secondary battery) and dried if necessary. These coating liquids can be applied sequentially. Further, in consideration of manufacturing efficiency, coating accuracy, etc., it is preferable to apply the coating at the same time. For this simultaneous coating, for example, a coating device in which a number of nozzles corresponding to the number of regions X and regions Y to be formed is arranged in a row is prepared, and a coating liquid for forming region X and a coating liquid for forming region Y are supplied from each nozzle. This can be done by moving the nozzles arranged in a row on the substrate while alternately discharging them so that they are in contact with each other at the same time.
Further, the negative electrode active material layer can be formed by methods such as self-assembly, etching treatment, optical imprinting, and inkjet, alone or in combination.

As the dispersion medium used in the coating liquid for forming region X, for example, an alcohol compound solvent, an ether compound solvent, an amide compound solvent, an amino compound solvent, a ketone compound solvent, an ester compound solvent, an aromatic compound solvent, an aliphatic compound solvent, and a nitrile. Examples include compound solvents.
Examples of the alcohol compound solvent include methyl alcohol, ethyl alcohol, 1-propyl alcohol, 2-butanol, ethylene glycol, propylene glycol, glycerin, 1,6-hexanediol, 1,3-butanediol, and 1,4-. Butanediol can be mentioned.

Examples of the ether compound solvent include alkylene glycol alkyl ethers (ethylene glycol monomethyl ether, ethylene glycol monobutyl ether, diethylene glycol, dipropylene glycol, propylene glycol monomethyl ether, diethylene glycol monomethyl ether, triethylene glycol, polyethylene glycol, propylene glycol dimethyl ether, and di. Propropylene glycol monomethyl ether, tripropylene glycol monomethyl ether, diethylene glycol monobutyl ether, diethylene glycol dibutyl ether, etc.), dialkyl ether (dimethyl ether, diethyl ether, dibutyl ether, etc.), tetrahydrofuran, and dioxane (1,2-, 1,3- and 1). , 4-Including each isomer).

Examples of the amide compound solvent include N, N-dimethylformamide, 1-methyl-2-pyrrolidone, 2-pyrrolidinone, 1,3-dimethyl-2-imidazolidinone, 2-pyrrolidinone, ε-caprolactam, formamide, and N. Included are-methylformamide, acetamide, N-methylacetamide, N, N-dimethylacetamide, N-methylpropanamide, and hexamethylphosphoric triamide.

Examples of the amino compound solvent include triethylamine and tributylamine.

Examples of the ketone compound solvent include acetone, methyl ethyl ketone, diethyl ketone, dipropyl ketone, dibutyl ketone, and diisobutyl ketone.

Examples of the ester compound solvent include methyl acetate, ethyl acetate, propyl acetate, butyl acetate, pentyl acetate, hexyl acetate, methyl propionate, ethyl propionate, propyl propionate, butyl propionate, methyl butyrate, ethyl butyrate, and propyl butyrate. , Butyrate butyl, isobutyl isobutyrate, pentyl butyrate, methyl valerate, ethyl valerate, propyl valerate, butyl valerate, methyl caproate, ethyl caproate, propyl caproate, butyl caproate and the like.

Examples of the aromatic compound solvent include benzene, toluene, xylene, and mesitylene.

Aliphatic compound solvents include, for example, hexane, heptane, cyclohexane, methylcyclohexane, ethylcyclohexane, decalin, octane, pentane, cyclopentane, and cyclooctane.

Examples of the nitrile compound solvent include acetonitrile, propyronitrile, and butyronitrile.

The above-mentioned coating liquid for forming region X itself can be prepared by a conventional method. Specifically, the constituent material of region X and the dispersion medium can be mixed and prepared. This mixing can be performed using various mixers. For example, ball mills, bead mills, planetary mixers, blade mixers, roll mills, kneaders, disc mills and the like can be mentioned. The content of each constituent material in the coating liquid is not particularly limited as long as a coating film exhibiting a desired function can be formed, and is appropriately set in consideration of film thickness, dispersibility and the like.

The coating liquid for forming the region Y can be prepared, for example, by dissolving the above-mentioned polymer constituting the region Y having a tensile elastic modulus of 700 MPa or less in a solvent or dispersing it in the solvent. The solvent used in the coating solution for forming the region Y can be appropriately selected depending on the type of polymer used, solubility and the like. Further, the content of the polymer in the coating liquid for forming the region Y can also be appropriately set according to the purpose in consideration of the thickness of the layer to be formed and the like.

The drying temperature of the formed coating film is not particularly limited, and is preferably 30 ° C. or higher, more preferably 60 ° C. or higher, and further preferably 80 ° C. or higher. The drying temperature is preferably 300 ° C. or lower, more preferably 250 ° C. or lower, and even more preferably 200 ° C. or lower.

The layers other than the negative electrode active material layer constituting the laminated structure of the all-solid-state secondary battery of the present invention will be described.

<Solid electrolyte layer>
The solid electrolyte layer constituting the all-solid-state secondary battery of the present invention contains the above-mentioned inorganic solid electrolyte and, if necessary, the binder described in the above-mentioned region X. The content of each component of the solid electrolyte layer can be appropriately adjusted according to the purpose. For example, the content of the inorganic solid electrolyte in the solid electrolyte layer is preferably 50% by mass or more, more preferably 70% by mass or more, further preferably 80% by mass or more, still more preferably 90% by mass or more.
When the solid electrolyte layer contains a binder, the content of the binder in the solid content of the solid electrolyte composition can be 1 to 20% by mass, preferably 2 to 15% by mass, more preferably 3 to 10% by mass.
The solid electrolyte layer constituting the all-solid secondary battery of the present invention is coated with, for example, a coating liquid (slurry) for forming a solid electrolyte layer containing the above-mentioned inorganic solid electrolyte, a binder if necessary, and the above-mentioned dispersion medium. Can be formed.

The solid electrolyte layer may contain a lithium salt (supporting electrolyte).
As the lithium salt, the lithium salt usually used for this kind of product is preferable, and there is no particular limitation. For example, the lithium salt described in paragraphs 0083-00885 of JP2015-088486 is preferable.
When the solid electrolyte-containing layer contains a lithium salt, the content of the lithium salt is preferably 0.1 part by mass or more, more preferably 5 parts by mass or more, based on 100 parts by mass of the inorganic solid electrolyte. The upper limit is preferably 50 parts by mass or less, more preferably 20 parts by mass or less.

The solid electrolyte layer may contain an ionic liquid in order to further improve the ionic conductivity. The ionic liquid is not particularly limited, but one that dissolves the above-mentioned lithium salt is preferable from the viewpoint of effectively improving the ionic conductivity. For example, a compound composed of a combination of the following cations and anions can be mentioned.

<Positive electrode active material layer>
The positive electrode active material layer constituting the all-solid-state secondary battery of the present invention can be formed of ordinary constituent materials used in the all-solid-state secondary battery. The positive electrode active material layer contains a positive electrode active material. The positive electrode active material layer may have the same structure as the above-mentioned solid electrolyte layer except that it contains the positive electrode active material.
The content of each component in the positive electrode active material layer can be appropriately adjusted according to the purpose. For example, the content of the positive electrode active material in the positive electrode active material layer can be 20 to 95% by mass, more preferably 30 to 90% by mass.
In the present invention, as the positive electrode active material layer, a positive electrode active material layer forming coating liquid containing the positive electrode active material is prepared in the above-mentioned solid electrolyte layer forming coating liquid (slurry), and this is used as a base material (current collector). Alternatively, it can be formed by applying it to a solid electrolyte layer, that is, a layer in contact with the positive electrode active material layer in an all-solid secondary battery).

(Positive electrode active material)
The positive electrode active material is preferably one capable of reversibly inserting and / or releasing lithium ions. The material is not particularly limited as long as it has the above-mentioned properties, and may be a transition metal oxide, an element that can be compounded with Li such as sulfur, or the like.
Among them, as the positive electrode active material, a transition metal oxide having preferably used a transition metal oxide, a transition metal element ^{M a (Co, Ni, Fe} , Mn, 1 or more elements selected from Cu and V) the The thing is more preferable. Further, the 1 (Ia) group elements of the transition metal oxide to elemental ^{M b} (Table metal periodic other than lithium, the elements of the 2 (IIa) group, Al, Ga, In, Ge , Sn, Pb, Elements such as Sb, Bi, Si, P and B) may be mixed. The mixing amount, 0~30mol% is preferred for the amount of the transition metal element ^{M a (100mol%).} That the molar ratio of li / ^{M a} is synthesized by mixing so that 0.3 to 2.2 is more preferable.
Specific examples of the transition metal oxide include (MA) a transition metal oxide having a layered rock salt type structure, (MB) a transition metal oxide having a spinel type structure, (MC) a lithium-containing transition metal phosphoric acid compound, and (MD). ) Lithium-containing transition metal halide phosphoric acid compound, (ME) lithium-containing transition metal silicic acid compound and the like can be mentioned.

(MA) Specific examples of the transition metal oxide having a layered rock salt structure include LiCoO ₂ (lithium cobalt oxide [LCO]), LiNi ₂ O ₂ (lithium nickel oxide), LiNi _0.85 Co _0.10 Al _{0. 05} O ₂ (Lithium Nickel Cobalt Oxide [NCA]), LiNi _1/3 Co _1/3 Mn _1/3 O ₂ (Lithium Nickel Manganese Cobalt Oxide [NMC]), LiNi _0.5 Mn _0.5 O ₂ ( Lithium manganese nickel oxide).
(MB) Specific examples of the transition metal oxide having a spinel _{structure, LiMn 2 O 4 (LMO)} , LiCoMnO 4, Li 2 FeMn 3 O 8, Li 2 CuMn 3 O 8, Li 2 CrMn 3 O 8 and Li ₂ Nimn ₃ O ₈ can be mentioned.
Examples of the (MC) lithium-containing transition metal phosphate compound include olivine-type iron phosphate salts such as _{LiFePO 4} and Li ₃ Fe ₂ (PO ₄ ) ₃ , iron pyrophosphates such as _{LiFeP 2} O _{7 , and LiCoPO 4.} Examples thereof include cobalt phosphates of Li ₃ V ₂ (PO ₄ ) ₃ (lithium vanadium phosphate) and other monoclinic pachicon-type vanadium phosphate salts.
(MD) as the lithium-containing transition metal halogenated phosphate compound, for _example, Li 2 FePO ₄ F such fluorinated phosphorus iron _salt, Li 2 MnPO ₄ hexafluorophosphate manganese salts such as F and _Li 2 CoPO ₄ F Fluorophosphate cobalts such as.
Examples of the (ME) lithium-containing transition metal silicic acid compound include Li ₂ FeSiO ₄ , Li ₂ MnSiO ₄ , and Li ₂ CoSiO ₄ .
In the present invention, a transition metal oxide having a (MA) layered rock salt type structure is preferable, and LCO or NMC is more preferable.

The shape of the positive electrode active material is not particularly limited, but is preferably in the form of particles. The average particle size (sphere-equivalent average particle size) of the positive electrode active material is not particularly limited. For example, it can be 0.1 to 50 μm. The average particle size of the positive electrode active material particles can be measured in the same manner as the average particle size of the inorganic solid electrolyte. In order to make the positive electrode active material have a predetermined particle size, a normal crusher or classifier is used in the same manner as the negative electrode active material.
The positive electrode active material obtained by the firing method may be used after being washed with water, an acidic aqueous solution, an alkaline aqueous solution, or an organic solvent.

Like the negative electrode active material, the positive electrode active material may be surface-coated with the above-mentioned surface coating agent, sulfur or phosphorus, and further with the above-mentioned active light rays or the like.

The positive electrode active material may be used alone or in combination of two or more.
When forming the positive electrode active material layer, the mass (mg) (grain amount) of the positive electrode active material per ^{unit area (cm 2) of the positive electrode active material layer is not particularly limited.} It can be appropriately determined according to the designed battery capacity. For example, it can be 1 to 100 mg / cm ^2.

The content of the positive electrode active material in the positive electrode active material layer is preferably 10 to 97% by mass, more preferably 30 to 95% by mass, further preferably 40 to 93% by mass, and particularly preferably 50 to 90% by mass.

In the all-solid-state secondary battery of the present invention, the thickness of each of the negative electrode active material layer, the solid electrolyte layer and the positive electrode active material layer is not particularly limited. The thickness of each layer is preferably 10 μm to 500 μm, more preferably 20 to 400 μm, and even more preferably 20 to 200 μm, respectively, considering the dimensions of a general all-solid-state secondary battery. Further, each layer of the negative electrode active material layer, the solid electrolyte layer and the positive electrode active material layer may be a single layer or a plurality of layers. In the case of multiple layers, it is preferable that the thickness of the entire multiple layers is within the above preferable range.

<Current collector>
The positive electrode current collector and the negative electrode current collector are preferably electron conductors. As a material for forming the positive electrode current collector, in addition to aluminum, aluminum alloy, stainless steel, nickel and titanium, the surface of aluminum or stainless steel is treated with carbon, nickel, titanium or silver (a thin film is formed). Of these, aluminum and aluminum alloys are more preferable.
As a material for forming the negative electrode current collector, in addition to aluminum, copper, copper alloy, stainless steel, nickel and titanium, carbon, nickel, titanium or silver is treated on the surface of aluminum, copper, copper alloy or stainless steel. Preferably, aluminum, copper, copper alloy and stainless steel are more preferable.

The shape of the current collector is usually a film sheet, but a net, a punched body, a lath body, a porous body, a foam body, a molded body of a fiber group, or the like can also be used.
The thickness of the current collector is not particularly limited, but is preferably 1 to 500 μm, more preferably 2 to 300 μm, and even more preferably 2 to 200 μm. Further, it is also preferable that the surface of the current collector is made uneven by surface treatment.

[Manufacturing of all-solid-state secondary batteries]
The laminated structure of the all-solid-state secondary battery of the present invention can be formed by a conventional method except that the structure of the negative electrode active material layer is the structure specified in the present invention described above. For example, the descriptions of JP-A-2018-106844, JP-A-2016-181448, JP-A-2016-081822, and the like can be referred to.
The obtained laminate is usually housed in an appropriate housing (sealed in a housing, housed in a coin case, etc.) and put into a pressurized state to form an all-solid-state secondary battery. The all-solid-state secondary battery according to the present invention has a polymer region in the negative electrode active material layer that absorbs the expansion of the negative electrode active material during charging and follows the shrinkage of the negative electrode active material during discharge. Sufficient cycle characteristics can be realized even if the pressurization of the above is set to a lower pressure condition than before.
The housing may be made of metal or resin (plastic). When a metallic material is used, for example, one made of aluminum alloy or stainless steel can be mentioned. It is preferable that the metallic housing is divided into a positive electrode side housing and a negative electrode side housing, and electrically connected to the positive electrode current collector and the negative electrode current collector, respectively. It is preferable that the housing on the positive electrode side and the housing on the negative electrode side are joined and integrated via a gasket for preventing a short circuit.

<Initialization>
The all-solid-state secondary battery manufactured as described above is preferably initialized after manufacturing or before use. The 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.

[Applications for all-solid-state secondary batteries]
The all-solid-state secondary battery obtained by the production method of the present invention can be applied to various uses. The application mode is not particularly limited, but for example, when mounted on an electronic device, a laptop 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. Examples include copying, mobile printers, headphone stereos, video movies, LCD TVs, handy cleaners, portable CDs, mini discs, electric shavers, transceivers, electronic notebooks, calculators, portable tape recorders, radios, backup power supplies, memory cards, etc. Other consumer products include automobiles (electric vehicles, etc.), 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 various munitions and space. It can also be combined with a solar cell.

[Negative electrode sheet for all-solid-state secondary battery]
The negative electrode sheet for an all-solid-state secondary battery of the present invention (also referred to as "negative electrode sheet of the present invention") is a sheet suitable as a material constituting the negative electrode of the all-solid-state secondary battery of the present invention.
That is, the negative electrode sheet of the present invention has a negative electrode active material layer, and the negative electrode active material layer is formed of a solid particle region X containing a negative electrode active material and an inorganic solid electrolyte and a polymer having a tensile elasticity of 700 MPa or less. It has a polymer region Y and the like. The solid particle region X and the polymer region Y are arranged in the negative electrode active material layer in a direction (L direction) perpendicular to the surface of the negative electrode active material layer and in one direction (Z direction) parallel to the surface of the negative electrode active material layer. ) Are also arranged side by side. In a cross section of the negative electrode active material layer perpendicular to the above-mentioned "one direction parallel to the surface of the negative electrode active material layer", the solid particle region X and the polymer region Y are alternately arranged in contact with each other. The relationship between ^{the width X w} of the solid particle regions X adjacent to each other in the cross section and the width Y ^{w of the polymer region Y satisfies 0.01 ≦ Y w} / X ^w ≦ 1.00. The interpretation of 0.01 ≤ Y ^w / X ^w ≤ 1.00, the method for determining ^{Y w} and X ^{w , and the preferred range of Y w} / X ^w are the description of the negative electrode active material layer in the all-solid-state secondary battery of the present invention. As described in.
Typical forms of the negative electrode sheet of the present invention include a two-layer structure in which the negative electrode active material layer is formed on the current collector, a positive electrode active material layer, a solid electrolyte layer, and the negative electrode activity on the current collector. Examples thereof include forms in which material layers are laminated in this order, but the negative electrode sheet of the present invention is not limited to these forms except as specified in the present invention.
The preferred forms of the current collector, the negative electrode active material layer, the solid electrolyte layer, and the positive electrode active material layer that can form the negative electrode sheet of the present invention are the same as those described in the above-described all-solid-state secondary battery of the present invention. ..

Hereinafter, the present invention will be described in more detail based on Examples. It should be noted that the present invention is not construed as being limited thereto.

[Sulfide-based inorganic solid electrolyte (Li-PS-based glass) synthesis]
Sulfide-based inorganic solid electrolytes are described in T.I. Ohtomo, A.M. Hayashi, M. et al. Tassumisago, Y. et al. Tsuchida, S.A. Hama, K.K. Kawamoto, Journal of Power Sources, 233, (2013), pp231-235 and A.M. Hayashi, S.A. Hama, H. Morimoto, M.D. Tatsumi sago, T. et al. Minami, Chem. Lett. , (2001), pp872-873, was synthesized with reference to the non-patent documents.

Specifically, in a glove box under an argon atmosphere (dew point -70 ° C.), lithium sulfide (Li ₂ S, manufactured by Aldrich, purity> 99.98%) 2.42 kg, diphosphorus pentasulfide (P ₂ S). _5. Aldrich, purity> 99%) 3.90 kg was weighed, put into an agate mortar, and mixed for 5 minutes using an agate mortar. The molar ratios of _{Li 2} S and P ₂ S _{5 were Li 2} S: P ₂ S ₅ = 75: 25.
66 zirconia beads having a diameter of 5 mm were put into a 45 mL container made of zirconia (manufactured by Fritsch), and the entire mixture of lithium sulfide and diphosphorus pentasulfide was put into the container, and the container was sealed under an argon atmosphere. A container is set in a planetary ball mill P-7 (trade name) manufactured by Fritsch, and mechanical milling is performed at a temperature of 25 ° C. and a rotation speed of 510 rpm for 20 hours. Glass, also referred to as "LPS") 6.20 g was obtained.

[Example of Synthesis of Polymer Constituting Binder B]
200 parts by mass of heptane was added to a 1 L three-necked flask equipped with a reflux condenser and a gas introduction cock, nitrogen gas was introduced at a flow rate of 200 mL / min for 10 minutes, and then the temperature was raised from room temperature to 80 ° C. In the stirring heptane, 90 parts by mass of a solution prepared in a separate container (butyl acrylate (manufactured by Wako Pure Chemical Industries, Ltd.), 20 parts by mass of methyl methacrylate (the above-exemplified compound, manufactured by Wako Pure Chemical Industries, Ltd.), Acrylic acid (manufactured by Wako Pure Chemical Industries, Ltd.) 10 parts by mass, B-27 (synthetic product described later) 20 parts by mass, macromonomer MM-1 (synthetic product described later) 60 parts by mass (solid content), polymerization initiator V A solution prepared by mixing 2.0 parts by mass of −601 (trade name, manufactured by Wako Pure Chemical Industries, Ltd.) was added dropwise over 2 hours, and then the mixture was stirred at 80 ° C. for 2 hours. Then, 1.0 part by mass of V-601 was further added to the obtained mixture, and the mixture was stirred at 90 ° C. for 2 hours. The obtained solution was diluted with heptane to obtain a dispersion of binder B. The volume average particle size of the binder B in this dispersion was 100 nm.

[Synthesis of B-27]
80 g of cholesterol (manufactured by Tokyo Chemical Industry Co., Ltd.), 50 g of monooxalate (2-acryloyloxyethyl) (manufactured by Aldrich), 5 g of 4-dimethylaminopyridine (manufactured by Tokyo Chemical Industry Co., Ltd.) in a 1 L three-necked flask. After adding 500 g of dichloromethane, the mixture was stirred at 20 ° C. for 5 minutes. 52 g of 1- (3-dimethylaminopropyl) -3-ethylcarbodiimide hydrochloride (manufactured by Tokyo Chemical Industry Co., Ltd.) was added to the stirring solution over 30 minutes, and the mixture was stirred at 20 ° C. for 5 hours. Then, it was washed with 0.1 M hydrochloric acid three times, dried over magnesium sulfate, and distilled under reduced pressure. The obtained sample was purified by silica gel column chromatography to obtain B-27.

[Synthesis of macromonomer MM-1]
190 parts by mass of toluene was added to a 1 L three-necked flask equipped with a reflux condenser and a gas introduction cock, nitrogen gas was introduced at a flow rate of 200 mL / min for 10 minutes, and then the temperature was raised from room temperature to 80 ° C. A solution prepared in a separate container (formulation α below) was added dropwise to the stirring toluene over 2 hours, and the mixture was stirred at 80 ° C. for 2 hours. Then, 0.2 parts by mass of V-601 (manufactured by Wako Pure Chemical Industries, Ltd.) was added, and the mixture was further stirred at 95 ° C. for 2 hours. 0.025 parts by mass of 2,2,6,6-tetramethylpiperidin-1-oxyl (manufactured by Tokyo Chemical Industry Co., Ltd.) and glycidyl methacrylate (manufactured by Wako Pure Chemical Industries, Ltd.) in a solution kept at 95 ° C. after stirring. 13 parts by mass and 2.5 parts by mass of tetrabutylammonium bromide (manufactured by Tokyo Chemical Industry Co., Ltd.) were added, and the mixture was stirred at 120 ° C. for 3 hours. The obtained mixture was cooled to room temperature and then added to methanol for precipitation. The precipitate was collected by filtration, washed twice with methanol, and then 300 parts by mass of heptane was added to dissolve the mixture. The obtained solution was concentrated under reduced pressure to obtain a solution of macromonomer MM-1. The solid content concentration was 43.4% by mass, the SP value was 9.1, and the mass average molecular weight was 16,000. The obtained macromonomer MM-1 is shown below.

(Prescription α)
Dodecyl Methacrylate (manufactured by Wako Pure Chemical Industries, Ltd.) 150 parts by mass Methyl methacrylate (manufactured by Wako Pure Chemical Industries, Ltd.) 59 parts by mass 3-mercaptoisobutyric acid (manufactured by Tokyo Chemical Industry Co., Ltd.) 2 parts by mass V-601 (Wako Pure Chemical Industries, Ltd.) (Made by Kogyo Co., Ltd.) 1.9 parts by mass

[Preparation of slurry for forming solid electrolyte layer]
130 zirconia beads having a diameter of 5 mm were placed in a 45 mL container made of zirconia (manufactured by Fritsch), 3.0 g of the LPS synthesized above, 0.09 g of the dispersion liquid of the binder B in terms of solid content, as a dispersion medium. 9.0 g of toluene was added. A container is set in a planetary ball mill P-7 (trade name) manufactured by Fritsch, and mixed at a temperature of 25 ° C. and a rotation speed of 100 rpm for 30 minutes to form a solid electrolyte layer containing LPS having a particle size of 2.0 μm. A slurry for forming a solid electrolyte layer was prepared.

[Preparation of slurry for forming positive electrode active material layer]
180 zirconia beads having a diameter of 5 mm were placed in a 45 mL container made of zirconia (manufactured by Fritsch), 2.8 g of the LPS synthesized above, 0.1 g of the dispersion liquid of the binder B in terms of solid content, as a dispersion medium. 12.3 g of toluene was added. The container was set on a planetary ball mill P-7 (trade name) manufactured by Fritsch, and mixed at a temperature of 25 ° C. and a rotation speed of 300 rpm for 2 hours. After that, 7.0 g of NMC (LiNi _0.33 Co _0.33 Mn _0.33 O ₂ (manufactured by Aldrich)) as an active material and 0.2 g of acetylene black (manufactured by Denka Co., Ltd.) as a conductive additive were placed in a 0.2 g container. Similarly, the container was set in the planetary ball mill P-7, and mixing was continued for 10 minutes at a temperature of 25 ° C. and a rotation speed of 100 rpm to prepare a slurry for forming a positive electrode active material layer.

[Preparation of slurry for forming solid particle region X of negative electrode active material layer]
180 zirconia beads having a diameter of 5 mm were put into a 45 mL container made of zirconia (manufactured by Fritsch), 4.7 g of LPS synthesized above, 0.1 g of the dispersion liquid of the binder B in terms of solid content, and heptane 12 as a dispersion medium. .3 g was added. The container was set on a planetary ball mill P-7 manufactured by Fritsch, and mixed at a temperature of 25 ° C. and a rotation speed of 300 rpm for 2 hours. Then, 4.7 g of silicon powder (manufactured by Alfa Aesar) as an active material and 0.5 g of acetylene black (manufactured by Denka) as a conductive auxiliary agent were put into a container, and similarly, the container was put into a planetary ball mill P-7. Was set, and mixing was continued for 15 minutes at a temperature of 25 ° C. and a rotation speed of 200 rpm to prepare a slurry for forming a solid particle region X.

[Preparation of coating liquid for forming polymer region Y of negative electrode active material layer]
4.5 g of a polyurethane elastomer having a tensile elastic modulus of 100 MPa (standard urethane altitude 95, obtained from Misumi) was added to 5.5 g of heptane, and mixed at 25 ° C. for 30 minutes at a rotation speed of 200 rpm using a magnet stirrer. In this way, a coating liquid for forming the polymer region Y, in which the polyurethane resin was dissolved, was prepared.

[Example 1] Fabrication of all-solid-state secondary battery [Positive sheet for all-solid-state secondary battery-Preparation of solid electrolyte sheet]
The slurry for forming the positive electrode active material layer prepared above was applied onto an aluminum foil (positive electrode current collector) having a thickness of 20 μm with an applicator (trade name: SA-201 Baker type applicator, manufactured by Tester Sangyo Co., Ltd.). After heating at 80 ° C. for 1 hour, the mixture was further heated at 110 ° C. for 1 hour to dry the slurry for forming the positive electrode active material layer. Then, using a heat press machine, pressure was applied while heating (120 ° C.) (180 MPa, 1 minute) to prepare a positive electrode sheet for an all-solid secondary battery having a laminated structure of a positive electrode active material layer / aluminum foil. The thickness of the positive electrode active material layer was 60 μm.
The slurry for forming the solid electrolyte layer prepared above is applied onto the positive electrode active material layer of the positive electrode sheet obtained above by the Baker type applicator, heated at 80 ° C. for 1 hour, and then further heated at 100 ° C. for 1 hour. Then, a solid electrolyte layer having a thickness of 20 μm was formed.

[Manufacturing of negative electrode sheet for all-solid-state secondary battery]
The slurry for forming the solid particle region X and the coating liquid for forming the polymer region Y prepared above are arranged in a straight line alternately on a copper foil (negative electrode current collector) having a thickness of 20 μm in contact with each other. Was applied to. For this coating, a coating device in which five nozzles were arranged in a row was used. Specifically, the nozzles arranged in a row are moved in a straight line on the copper foil so that the slurry for forming the solid particle region X and the coating liquid for forming the polymer region Y are discharged from the nozzles adjacent to each other. While simultaneously discharging the slurry for forming the solid particle region X and the coating liquid for forming the polymer region Y, a coating film was formed. Of the five nozzles, the outermost nozzle and the central nozzle (the first, third, and fifth nozzles in order from the end) discharge the solid particle region X forming slurry, and the other nozzles (from the end). The coating liquid for forming the polymer region Y was discharged from the second and fourth nozzles).
Then, after heating at 80 ° C. for 1 hour, further heating at 110 ° C. for 1 hour was performed to dry the slurry or coating liquid. Then, using a heat press machine, pressure was applied while heating (120 ° C.) (120 MPa, 1 minute) to prepare a negative electrode sheet for an all-solid secondary battery having a laminated structure of a negative electrode active material layer / copper foil. The thickness of the negative electrode active material layer was 60 μm. ^{In the formed negative electrode active material layer, the width X w} of the solid particle region X corresponding to each nozzle was set to ^{40 mm, and the width Y w} of the polymer region Y corresponding to each nozzle was set to 0.4 mm (Y ^w / X ^w). = 0.01).

[Manufacturing of all-solid-state secondary battery]
On the "positive electrode sheet for all-solid-state secondary battery-solid electrolyte sheet" prepared above, the "negative electrode sheet for all-solid-state secondary battery" is layered so that the solid electrolyte layer and the negative electrode active material layer are in contact with each other, and 10 at 50 MPa. Pressurized for seconds. An all-solid-state battery (laminate cell) was produced by making the obtained laminate into a 120 mm square size and vacuum-sealing the laminate.

[Examples 2 to 12, Comparative Examples 1 to 5] Preparation of all-solid-state secondary battery The types of the negative electrode active material, the inorganic solid electrolyte, the binder, and the polymer forming the polymer region Y are changed as shown in the table below. Further, an all-solid-state secondary battery was produced in the same manner as in Example 1 except that the width of the solid particle region X and the width of the polymer region Y in the negative electrode active material layer were changed as shown in the table below. The inorganic solid electrolyte and the binder were changed as shown in the table below in all the layers of the negative electrode active material layer, the positive electrode active material layer and the solid electrolyte layer. The amounts of the negative electrode active material, the inorganic solid electrolyte, the binder, and the polymer forming the polymer region Y are the same as in Example 1.

[Evaluation of battery performance]
The battery performance of the all-solid-state secondary battery was evaluated using a charge / discharge evaluation device "TOSCAT-3000" (trade name) manufactured by Toyo Systems Co., Ltd. Specifically, the all-solid-state secondary battery was charged with a current value of 0.2 mA until the battery voltage reached 4.2 V, and then discharged at a current value of 2.0 mA until the battery voltage reached 3.0 V. The battery voltage 10 seconds after the start of discharge was read according to the following criteria, and evaluated by applying the following criteria. The higher the battery voltage 10 seconds after the start of discharge, the lower the resistance.
<Battery performance (resistance) evaluation criteria>
AA: 4.10V or more A: 4.05V or more and less than 4.10V B: 4.00V or more and less than 4.05V C: 3.90V or more and less than 4.00V D: Less than 3.90V E: A short circuit occurred.
[Test Example] Evaluation of cycle characteristics The cycle characteristics of an all-solid-state secondary battery were evaluated using a charge / discharge evaluation device "TOSCAT-3000" (trade name) manufactured by Toyo Systems Co., Ltd. Specifically, using the battery produced above, charging / discharging of 4.2 V to 3.0 V was repeated four times at 30 ° C. with a charging current value of 0.35 mA and a discharge current value of 0.7 mA.
Then, as a cycle test, a test was carried out in which charging / discharging of 4.2 V to 3.0 V was repeated under the condition of a charge / discharge current value of 0.7 mA in an environment of 30 ° C.
In this cycle test, the number of cycles in which the discharge capacity was 80% when the discharge capacity in the first cycle was 100% was evaluated by applying the following evaluation criteria.
By this test, it is possible to grasp whether the electron / ion path of the negative electrode active material in the negative electrode layer can be maintained when the battery is operated at 4.2 V.
<Cycle characterization criteria>
AA: Number of cycles 200 or more A: Number of cycles 100 to 199 B: Number of cycles 50 to 99 C: Number of cycles 21 to 49 D: Number of cycles 11 to 20 E: Number of cycles 0 to 10 Shown in the table.

The abbreviations in the above table will be described below.
-Negative electrode active material-
Si: Silicon powder 1-5 μm (manufactured by Alfa Aesar)
C: Graphite (manufactured by Showa Denko)
-Inorganic solid electrolyte-
Sulfide-based: Li-PS-based glass Oxide-based: LLZ: Li ₇ La ₃ Zr ₂ O ₁₂ (Lithium lanthanum zirconate, average particle size 5.0 μm, Toyoshima Seisakusho)
-Binder-
Particulate matter: The dispersion liquid of the binder B was used.
Solubility: A binder solution in which styrene-butadiene rubber (styrene-butadiene block copolymer, manufactured by Zeon Corporation) was dissolved in heptane was used.
-Polymer in polymer region Y-
PU1: Polyurethane elastomer (tensile elastic modulus 100 MPa, manufactured by BASF)
PU2: Polyurethane elastomer (tensile elastic modulus 500 MPa, manufactured by BASF)
PU3: Polyurethane elastomer (tensile elastic modulus 690 MPa, manufactured by BASF)
SBR: Styrene-butadiene rubber (styrene-butadiene block copolymer, soluble in heptane, tensile modulus 100 MPa, manufactured by JSR Corporation)
High-density PE: High-density polyethylene (tensile elastic modulus 1000 MPa, manufactured by BASF)

As shown in the above table, when the negative electrode active material layer does not have a polymer region and is formed only in the solid particle region, the result is that the cycle characteristics are inferior (Comparative Example 1).
Further, even if the negative electrode active material layer has a polymer region, if the tensile elastic modulus of the polymer constituting the polymer region is higher than the specification of the present invention (700 MPa or less), the cycle characteristics are still inferior (Comparative Example). 5).
Further, even if the negative electrode active material layer has a polymer region and the tensile elastic modulus of the polymer constituting this polymer region is within the provisions of the present invention, the relationship between the width of the solid particle region and the width of the polymer region (Y ^w). When / X ^w ) was smaller than the specification of the present invention, the result was also inferior in cycle characteristics (Comparative Examples 2 and 3). On the contrary, when Y ^w / X ^w is larger than the specification of the present invention, the cycle characteristics are excellent, but the battery resistance is high and the performance is inferior (Comparative Example 4).
On the other hand, the all-solid-state secondary battery of the present invention, in which the composition of the negative electrode active material layer satisfies the provisions of the present invention, is excellent in cycle characteristics while suppressing an increase in resistance (Examples 1 to 12).

Although the present invention has been described with its embodiments, we do not intend to limit our invention in any detail of the description unless otherwise specified, and contrary to the spirit and scope of the invention set forth in the appended claims. I think that it should be widely interpreted without.

The present application claims priority based on Japanese Patent Application No. 2018-175752, which was filed in Japan on September 20, 2018, which is referred to herein and is described herein. Incorporate as a part.

101 All-solid secondary battery 11 Negative electrode current collector 12 Negative electrode active material layer 13 Solid electrolyte layer 14 Positive electrode active material layer 15 Positive electrode current collector layer 16 Operating parts 1a, 1b, 1c Solid particle region 2a, 2b Polymer region L Lamination direction (Direction perpendicular to the surface of the negative electrode active material layer)
Z Depth direction of the negative electrode active material layer (one direction parallel to the surface of the negative electrode active material layer)
X ^w Width of solid particle region Y ^w Width of polymer region

Claims (8)

An all-solid-state secondary battery having a laminated structure in which a negative electrode active material layer, a solid electrolyte layer, and a positive electrode active material layer are laminated in this order.
The negative electrode active material layer has a solid particle region X containing a negative electrode active material and an inorganic solid electrolyte, and a polymer region Y formed of a polymer having a tensile elastic modulus of 700 MPa or less.
The solid particle region X and the polymer region Y are arranged in the negative electrode active material layer in the laminating direction of the laminated structure and also in one direction perpendicular to the laminating direction.
In a cross section of the negative electrode active material layer perpendicular to one direction perpendicular to the stacking direction, the solid particle region X and the polymer region Y are alternately arranged in contact with each other, and in the cross section, the solid particle region X and the polymer region Y are arranged in contact with each other. An all-solid-state secondary battery in which the relationship between the widths of both the solid particle region X and the polymer region Y adjacent to each other satisfies the following equation.
0.01 ≤ Y ^w / X ^w ≤ 1.00
X ^w : Width of solid particle region X Y ^w : Width of polymer region Y The all-solid-state secondary battery according to claim 1, wherein the solid-state particle region X contains a particulate binder. The all-solid-state secondary battery according to claim 1 or 2, wherein the negative electrode active material is a silicon-based negative electrode active material. The all-solid-state secondary battery according to any one of claims 1 to 3, wherein the inorganic solid electrolyte is a sulfide-based inorganic solid electrolyte. The all-solid-state secondary battery according to any one of claims 1 to 4, wherein the polymer having a tensile elastic modulus of 700 MPa or less is an elastomer. An electronic device having an all-solid-state secondary battery according to any one of claims 1 to 5. An electric vehicle having an all-solid-state secondary battery according to any one of claims 1 to 5. A negative electrode sheet for an all-solid-state secondary battery having a negative electrode active material layer.
The negative electrode active material layer has a solid particle region X containing a negative electrode active material and an inorganic solid electrolyte, and a polymer region Y formed of a polymer having a tensile elastic modulus of 700 MPa or less.
The solid particle region X and the polymer region Y are arranged in the negative electrode active material layer in a direction perpendicular to the surface of the negative electrode active material layer and also in one direction parallel to the surface of the negative electrode active material layer. Arranged in
In a cross section of the negative electrode active material layer parallel to the surface of the negative electrode active material layer and perpendicular to one direction, the solid particle region X and the polymer region Y are alternately arranged in contact with each other. A negative electrode sheet for an all-solid-state secondary battery in which the relationship between the widths of both the solid particle region X and the polymer region Y adjacent to each other in the cross section satisfies the following formula.
0.01 ≤ Y ^w / X ^w ≤ 1.00
X ^w : Width of solid particle region X Y ^w : Width of polymer region Y

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