WO2017104583A1

WO2017104583A1 - All-solid secondary battery, electrode sheet for all-solid secondary battery, and method of manufacturing said battery and sheet

Info

Publication number: WO2017104583A1
Application number: PCT/JP2016/086820
Authority: WO
Inventors: 目黒　克彦; 宏顕望月
Original assignee: 富士フイルム株式会社
Priority date: 2015-12-14
Filing date: 2016-12-09
Publication date: 2017-06-22
Also published as: JPWO2017104583A1; JP6640874B2

Abstract

An all-solid secondary battery, a method for manufacturing the same, an electrode sheet for an all-solid secondary battery, and a method for manufacturing the same, said battery being provided with a cathode that has an electroconductive film and a cathode active material layer in the stated order on the surface of a collector, an anode that has an anode active material layer, and an inorganic solid electrolyte layer between the cathode active material layer and the anode active material layer; the surface of the collector having an arithmetic average roughness Ra of 0.24 to 0.38 µm, and 10 to 80 recesses per 100 µm²; and said recesses having an average opening diameter of 0.3 to 3.0 µm.

Description

All-solid-state secondary battery, electrode sheet for all-solid-state secondary battery, and production method thereof

The present invention relates to an all-solid-state secondary battery, an electrode sheet for an all-solid-state secondary battery, and methods for producing them.

A lithium ion secondary battery is a storage battery that has a negative electrode, a positive electrode, and an electrolyte sandwiched between the negative electrode and the positive electrode, and can be charged and discharged by reciprocating lithium ions between the two electrodes. Conventionally, an organic electrolytic solution has been used as an electrolyte in a lithium ion secondary battery. However, the organic electrolyte is liable to leak, and there is a possibility that a short circuit occurs inside the battery due to overcharge and overdischarge, resulting in ignition, and further improvements in reliability and safety are required.
Under such circumstances, an all-solid secondary battery using an inorganic solid electrolyte instead of an organic electrolyte has been attracting attention. The all-solid-state secondary battery consists of a solid negative electrode, electrolyte, and positive electrode, which can greatly improve safety and reliability, which is a problem of batteries using organic electrolytes, and can extend the service life. It will be. Furthermore, the all-solid-state secondary battery can have a structure in which electrodes and an electrolyte are directly arranged in series. Therefore, it is possible to increase the energy density compared to a secondary battery using an organic electrolyte, and application to an electric vehicle or a large storage battery is expected.

The electrode of the all-solid-state secondary battery has a current collector and an active material layer formed on the current collector. In this electrode, a conductive film may be provided between the current collector and the active material layer for the purpose of improving the adhesion between the active material layer and the current collector or good ionic conductivity of the electrode (for example, Patent Document 1).

Japanese Patent Laying-Open No. 2015-5421

In the all solid state secondary battery, since the inorganic solid electrolyte is usually fine particles, a certain amount of fine voids (also simply referred to as voids) are generated between the electrolyte particles forming the solid electrolyte layer. It is considered that reducing the voids between the particles greatly contributes to improvement of battery characteristics such as ion conductivity. This applies to the case where the electrode is formed using a particulate electrode active material, preferably a particulate inorganic solid electrolyte. Therefore, in an all-solid-state secondary battery using solid particles such as an electrode active material or an inorganic solid electrolyte, a pressure load is applied to the solid particles of the inorganic solid electrolyte layer or the active material layer in order to exert a desired ionic conductivity. To reduce the voids between the particles.
However, if a pressure load is excessively applied during production or use, the conductive film provided on the electrode is peeled off from the current collector, and the ionic conductivity between the current collector and the active material layer is lowered. In addition, the inorganic solid electrolyte breaks through (breaks) the conductive film, or the electrode active material breaks through the conductive film provided on the counter electrode, and a short circuit occurs.
Thus, in an all-solid-state secondary battery subjected to a pressure load, a pressure load for improving ion conductivity (reduction of inter-particle voids), prevention of peeling of the conductive film and prevention of short circuit (damage prevention) Is in a trade-off relationship. Therefore, the performance of the conventional all-solid secondary battery is not sufficient and there is room for improvement.

Even if the present invention has an inorganic solid electrolyte layer closely packed with an inorganic solid electrolyte, it is possible to ensure the adhesion between the current collector and the conductive film and further prevent the occurrence of a short circuit. It is an object to provide a secondary battery and a manufacturing method thereof. Moreover, this invention makes it a subject to provide the electrode sheet for all-solid-state secondary batteries used suitably for the said all-solid-state secondary battery, and its manufacturing method.
In the present invention, the term “closely packed with an inorganic solid electrolyte” means that a fine void having no substance such as a binder (binder) between particles of the inorganic solid electrolyte substantially reduces ionic conductivity. This means filling the inorganic solid electrolyte in a state where it does not exist to the extent that it does not affect (forming an inorganic solid electrolyte layer). The level that does not have a substantial effect cannot be uniquely determined. For example, when the cross section (63 μm × 48 μm) of the all-solid-state secondary battery is observed with a scanning microscope at a magnification of 3000 times, It can be set to such an extent that voids originating from the interface (which cannot be uniquely determined, but usually have a diameter or major axis length of 1 μm or more) cannot be confirmed.

In the all-solid-state secondary battery provided with the conductive film, the present inventors examined the effect on the battery when a pressure load was applied. The conductive film was formed into a thin film by vapor deposition or the like, In addition to this, by setting the surface of the current collector on which the conductive film is provided to a specific surface morphology, the interaction between the conductive film and the surface of the current collector is enhanced, and pressure is applied. It has been found that even when a load acts, high adhesion between the current collector and the conductive film can be secured, and occurrence of a short circuit can be prevented. The present invention has been further studied based on these findings and has been completed.

That is, the above problem has been solved by the following means.
<1> A positive electrode having a conductive film and a positive electrode active material layer in this order on the surface of a current collector, a negative electrode having a negative electrode active material layer, and an inorganic solid electrolyte layer between the positive electrode active material layer and the negative electrode active material layer An all solid state secondary battery comprising:
The surface of the current collector of the positive electrode has an arithmetic average roughness Ra of 0.24 to 0.38 μm, and 10 to 80 recesses / 100 μm ² having an average opening diameter of 0.3 to 3.0 μm. All-solid secondary battery.
<2> The negative electrode has a conductive film and a negative electrode active material layer in this order on the surface of the current collector,
The surface of the current collector of the negative electrode has an arithmetic average roughness Ra of 0.24 to 0.38 μm, and 10 to 80 concave portions with an average opening diameter of 0.3 to 3.0 μm / 100 μm ^2. The all-solid-state secondary battery as described in <1>.
<3> The all-solid secondary according to <1> or <2>, wherein the surface has an arithmetic average roughness Ra of 0.25 to 0.31, and the number of recesses is 40 to 70/100 μm ² battery.
<4> The all-solid-state secondary battery according to any one of <1> to <3>, wherein the conductive film is a film of a metal, a metal oxide, or a carbonaceous material.
<5> A current collector having a surface having an arithmetic average roughness Ra of 0.24 to 0.38 μm and 10 to 80 concave portions with an average opening diameter of 0.3 to 3.0 μm / 100 μm ² An electrode sheet for an all-solid-state secondary battery having a conductive film and an active material layer in this order on the surface.
<6> A current collector having a surface having an arithmetic average roughness Ra of 0.24 to 0.38 μm and a recess having an average opening diameter of 0.3 to 3.0 μm of 10 to 80/100 μm ² The manufacturing method of the electrode sheet for all-solid-state secondary batteries which forms a conductive film on the surface and then forms an active material layer.
<7> The method for producing an electrode sheet for an all-solid-state secondary battery according to <6>, wherein the surface of the current collector is roughened by an electrochemical roughening treatment.
<8> The method for producing an electrode sheet for an all-solid-state secondary battery according to <6> or <7>, wherein the conductive film is formed by a vapor deposition method or a coating method using a metal, a metal oxide, or a carbonaceous material.
<9> A method for producing an all-solid secondary battery, including the method for producing an electrode sheet for an all-solid secondary battery according to any one of <6> to <8>.

In the present specification, a numerical range expressed using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.
In the present specification, when “acryl” is simply described, it means methacryl and / or acryl.

Even if the all-solid-state secondary battery of the present invention has an inorganic solid electrolyte layer closely packed with an inorganic solid electrolyte, it can ensure the adhesion between the current collector and the conductive film, and further, the occurrence of a short circuit. Can also be prevented. Moreover, the electrode sheet for all-solid-state secondary batteries of this invention can be used suitably for the all-solid-state secondary battery which has said outstanding characteristic.
The above and other features and advantages of the present invention will become more apparent from the following description, with reference where appropriate to the accompanying drawings.

It is a longitudinal cross-sectional view which shows typically the all-solid-state secondary battery which concerns on preferable embodiment of this invention. It is a longitudinal cross-sectional view which shows typically the all-solid-state secondary battery (coin battery) produced in the Example.

The all solid state secondary battery of the present invention has a positive electrode, a negative electrode facing the positive electrode, and a solid electrolyte layer between the positive electrode and the negative electrode. The positive electrode has a positive electrode conductive film and a positive electrode active material layer in this order on the surface of the positive electrode current collector. The negative electrode has a negative electrode active material layer on the negative electrode current collector, and may have a negative electrode conductive film on the surface of the negative electrode current collector on which the negative electrode active material layer is formed. The positive electrode current collector forming the positive electrode has a specific surface form (uneven structure) described later. When the negative electrode current collector that forms the negative electrode includes a negative electrode conductive film, the surface on which the negative electrode conductive film is formed preferably has the same surface form as the positive electrode current collector.
Hereinafter, preferred embodiments of the present invention will be described, but the present invention is not limited thereto.

[All-solid secondary battery]
FIG. 1 is a cross-sectional view schematically showing an all solid state secondary battery (lithium ion secondary battery) according to a preferred embodiment of the present invention. The all-solid-state secondary battery 10 according to this embodiment includes a negative electrode current collector 1, a negative electrode conductive film 7, a negative electrode active material layer 2, a solid electrolyte layer 3, a positive electrode active material layer 4, and a positive electrode conductive film as viewed from the negative electrode side. 8. It has a structure in which the positive electrode current collector 5 is laminated in this order, and adjacent layers are in direct contact with each other. By adopting such a structure, at the time of charging, electrons (e ⁻ ) are supplied to the negative electrode side, and lithium ions (Li ⁺ ) are accumulated therein. On the other hand, at the time of discharging, lithium ions (Li ⁺ ) accumulated in the negative electrode are returned to the positive electrode side, and electrons can be supplied to the working part 6. In the example of the illustrated all-solid-state secondary battery, a light bulb is adopted as a model for the operation site 6 and is lit by discharge.

[Current collector (metal foil)]
The positive electrode current collector 5 and the negative electrode current collector 1 are preferably electronic conductors.
In the present invention, either or both of the positive electrode current collector and the negative electrode current collector may be simply referred to as a current collector.
As a material for forming the positive electrode current collector, aluminum, aluminum alloy, stainless steel, nickel, titanium and the like are preferable, and among them, aluminum and aluminum alloy are more preferable.
As the material for forming the negative electrode current collector, aluminum, copper, copper alloy, stainless steel, nickel, and titanium are preferable, and aluminum, copper, and copper alloy are more preferable.

The shape of the current collector is usually a film sheet, but if a conductive film can be formed, the net, punched, lath, porous, foam, and fiber group are formed. The body can also be used.
The thickness of the current collector is not particularly limited, but is preferably 1 to 500 μm.

The positive electrode current collector has the following surface form on the surface on which the positive electrode conductive film is formed.
(1) Arithmetic mean roughness Ra is 0.24 to 0.38 μm
(2) The number of recesses having an average opening diameter of 0.3 to 3.0 μm is 10 to 80/100 μm ²

The arithmetic average roughness Ra is 0.24 to 0.38 μm. When the arithmetic average roughness Ra is smaller than 0.24 μm, the adhesion between the positive electrode current collector and the positive electrode conductive film is not sufficient, and the positive electrode conductive film may be peeled off from the positive electrode current collector. On the other hand, if the arithmetic average roughness Ra is larger than 0.38 μm, the all solid state secondary battery may be short-circuited. Further, the positive electrode conductive film may be peeled off. Arithmetic average roughness Ra is preferably 0.25 to 0.37 μm, more preferably 0.25 to 0.31 μm, in terms of adhesion between the positive electrode current collector and the positive electrode conductive film and prevention of occurrence of short circuit. preferable.

The arithmetic average roughness Ra is an arithmetic average roughness measured according to JIS B0601: 2010 using a stylus type surface roughness meter (for example, a surface roughness measuring machine SJ-401 manufactured by Mitutoyo Corporation). .

The positive electrode current collector has a recess on its surface. The concave portion is not particularly limited with respect to the average opening diameter, but the concave portion having an average opening diameter of 0.3 to 3.0 μm includes the adhesion between the positive electrode current collector and the positive electrode conductive film, And it is important in terms of preventing the occurrence of short circuits. The average opening diameter of the recesses is preferably 0.8 to 3.0 μm.
In the present invention, the surface of the positive electrode current collector has 10 to 80 recesses having an average opening diameter of 0.3 to 3.0 μm per surface area of 100 μm ² . If the number of concave portions with the average opening diameter per unit surface area (sometimes referred to as the number of concave portions) is less than 10, the adhesion between the positive electrode current collector and the positive electrode conductive film is not sufficient, and the positive electrode current collector In some cases, the positive electrode conductive film may peel off. On the other hand, if the number of recesses is more than 80, the peripheral edge of each opening becomes a protrusion, and the short circuit may increase during a pressure load. In terms of adhesion between the positive electrode current collector and the positive electrode conductive film and prevention of short circuit, the number of recesses is preferably 15 to 70, more preferably 20 to 70, and still more preferably 40 to 70.

In the present invention, by setting the arithmetic average roughness Ra and the number of recesses within the above ranges, the interaction with the positive electrode conductive film formed on the thin film is increased, and a pressure load force is applied during and after production. Even if the inorganic solid electrolyte is closely packed, the adhesion between the positive electrode current collector and the positive electrode conductive film and the occurrence of a short circuit can be achieved at a high level.

The opening diameter of a recessed part means the opening diameter of a recessed part, and the average opening diameter of a recessed part is the average value.
Specifically, using a high-resolution scanning electron microscope (SEM), the surface of the positive electrode current collector was photographed at a magnification of 2000 times from directly above, and in the obtained SEM image, the periphery (“the opening of the recess was defined). At least 50 concave portions having a substantially circular shape (annular shape) are extracted, and the diameter is read as an opening diameter to calculate an average opening diameter.
In addition, when one recessed part overlaps with another recessed part, it does not extract as a recessed part.
Further, in the obtained SEM image, a recess having an opening diameter of 0.3 to 3.0 μm existing in a 10 μm × 10 μm region (arbitrary three regions) (limited to a recess in which the edge of the opening is continuous in an annular shape) Is counted for each region, and the average value is calculated as the number of recesses (pieces / 100 μm ² ).

Although the surface form of the negative electrode current collector is not particularly limited, it is preferable that the negative electrode current collector has a surface form satisfying the above (1) and (2) as in the positive electrode current collector. In this case, the surface forms of the positive electrode current collector and the negative electrode current collector may be the same or different.

[Conductive film]
The conductive film (positive electrode conductive film) 8 forming the positive electrode may be any film formed of a conductive material.
Examples of the conductive material include conductive particles such as metals, metal oxides, and carbonaceous materials. Examples of the metal include copper, nickel, chromium, aluminum, platinum, silver, zinc, titanium, indium, antimony, bismuth, cobalt, tungsten, molybdenum, and alloys thereof. As a metal oxide, the said metal oxide is mentioned, for example. As a carbonaceous material, the carbonaceous material demonstrated with the conductive support agent mentioned later is mentioned, for example. Among these, metals or carbonaceous materials are preferable, carbonaceous materials are more preferable, and graphite or carbon nanotubes (CNT) are more preferable.

The film thickness of the positive electrode conductive film is not particularly limited, but is preferably 0.05 to 50 μm, more preferably 0.1 to 30 μm in terms of adhesion to the positive electrode current collector, stress relaxation under pressure load, and the like. preferable.
The positive electrode conductive film is not a solid fine particle of a conductive material, but is formed into a thin film by a coating (printing) method, a vapor deposition method, a plating method, or the like, and has an adhesive property with a positive electrode current collector and a conductive material. From the viewpoint of improving the property, it is preferable.

This positive electrode conductive film preferably has a low volume resistivity because of its characteristics, and those having a volume resistivity of 0.5Ω-cm or less, for example, 1 × 10 ⁻¹ to 1 × 10 ⁻⁵ Ω-cm are used. it can. The volume resistivity is preferably 5 × 10 ⁻² to 5 × 10 ⁻⁵ Ω-cm, more preferably 1 × 10 ⁻² to 1 × 10 ⁻⁴ Ω-cm.

When the negative electrode includes a conductive film (negative electrode conductive film) 7, the negative electrode conductive film is synonymous with the positive electrode conductive film, and preferable ones are also the same. However, the type and thickness of the material having conductivity may be the same as or different from those of the positive electrode conductive film.
In the present invention, either or both of the positive electrode conductive film and the negative electrode conductive film may be simply referred to as a conductive film.

[Positive electrode active material layer, solid electrolyte layer, negative electrode active material layer]
The thicknesses of the positive electrode active material layer 4, the solid electrolyte layer 3, and the negative electrode active material layer 2 are not particularly limited. Considering general battery dimensions, the thickness of each of the above layers is preferably 10 to 1,000 μm, more preferably 20 μm or more and less than 500 μm. In the all solid state secondary battery of the present invention, it is more preferable that the thickness of at least one of the positive electrode active material layer 4, the solid electrolyte layer 3 and the negative electrode active material layer 2 is 50 μm or more and less than 500 μm.

The solid electrolyte layer 3 contains an inorganic solid electrolyte, and preferably contains a binder from the viewpoint of improving the binding between solid particles and between layers. The solid electrolyte layer usually does not contain a positive electrode active material and / or a negative electrode active material. The positive electrode active material layer 4 and the negative electrode active material layer 2 each contain a positive electrode active material or a negative electrode active material, and preferably contain a solid electrolyte from the viewpoint of improving ion conductivity. Each active material layer preferably contains a binder from the viewpoint of improving the binding between the solid particles, the active material layer-solid electrolyte layer, and the active material layer-conductive film.
The inorganic solid electrolyte and the binder contained in the positive electrode active material layer 4, the solid electrolyte layer 3, and the negative electrode active material layer 2 may be the same or different from each other.
In the present invention, one or both of the positive electrode active material and the negative electrode active material may be simply referred to as an active material or an electrode active material. One or both of the positive electrode active material layer and the negative electrode active material layer may be simply referred to as an active material layer.

(Inorganic solid electrolyte)
The inorganic solid electrolyte is an inorganic solid electrolyte, and the solid electrolyte is a solid electrolyte capable of moving ions inside. Since it does not contain organic substances as the main ion conductive material, organic solid electrolytes (polymer electrolytes typified by polyethylene oxide (PEO), etc., organics typified by lithium bis (trifluoromethanesulfonyl) imide (LiTFSI), etc. It is clearly distinguished from the electrolyte salt). Further, since the inorganic solid electrolyte is solid in a steady state, it is not dissociated or released into cations and anions. In this respect, it is also clearly distinguished from inorganic electrolyte salts (LiPF ₆ , LiBF ₄ , lithium bis (fluorosulfonyl) imide (LiFSI), LiCl, etc.) in which cations and anions are dissociated or liberated in the electrolyte or polymer. . The inorganic solid electrolyte is not particularly limited as long as it has conductivity of ions of metal elements belonging to Group 1 or Group 2 of the periodic table, and generally does not have electron conductivity.

In the present invention, the inorganic solid electrolyte has ion conductivity of a metal element belonging to Group 1 or Group 2 of the periodic table. When the all solid state secondary battery of the present invention is a lithium ion battery, the inorganic solid electrolyte preferably has an ionic conductivity of lithium ions.
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 inorganic solid electrolytes include (i) sulfide-based inorganic solid electrolytes and (ii) oxide-based inorganic solid electrolytes. In the present invention, a sulfide-based inorganic solid electrolyte is preferably used from the viewpoint that a better interface can be formed 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 (S) and has ionic conductivity of a metal element belonging to Group 1 or Group 2 of the periodic table, And what has electronic insulation is preferable. The sulfide-based inorganic solid electrolyte preferably contains at least Li, S, and P as elements and has lithium ion conductivity. However, depending on the purpose or the case, other than Li, S, and P may be used. An element may be included.
For example, a lithium ion conductive inorganic solid electrolyte that satisfies the composition represented by the following formula (A) can be mentioned and is preferable.

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

In the formula, L represents an element selected from Li, Na and K, and Li is preferred.
M represents an element selected from B, Zn, Sn, Si, Cu, Ga, Sb, Al, and Ge. Among these, B, Sn, Si, Al, or Ge is preferable, and Sn, Al, or Ge is more preferable.
A represents I, Br, Cl or F, preferably I or Br, and particularly preferably I.
L, M, and A can each be one or more of the above elements.
a1 to e1 indicate the composition ratio of each element, and a1: b1: c1: d1: e1 satisfies 1 to 12: 0 to 1: 1: 2 to 12: 0 to 5. a1 is further preferably 1 to 9, and more preferably 1.5 to 4. b1 is preferably 0 to 0.5. Further, d1 is preferably 3 to 7, and more preferably 3.25 to 4.5. Further, e1 is preferably 0 to 3, more preferably 0 to 1.

In the formula (A), the composition ratio of L, M, P, S and A is preferably such that b1 and e1 are 0, more preferably b1 = 0 and e1 = 0 and the ratio of a1, c1 and d1 is a1: c1: d1 = 1-9: 1: 3-7, more preferably b1 = 0 and e1 = 0 and a1: c1: d1 = 1.5-4: 1: 3.25-4. 5. As will be described later, 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.

The sulfide-based inorganic solid electrolyte may be amorphous (glass) or crystallized (glass ceramic), or only a part may be crystallized. For example, Li—PS system glass containing Li, P, and S, or Li—PS system glass ceramics containing Li, P, and S can be used.
The sulfide-based inorganic solid electrolyte includes [1] lithium sulfide (Li ₂ S) and phosphorus sulfide (for example, diphosphorus pentasulfide (P ₂ S ₅ )), [2] lithium sulfide and at least one of simple phosphorus and simple sulfur, Or [3] It can be produced by the reaction of lithium sulfide, phosphorus sulfide (for example, diphosphorus pentasulfide (P ₂ S ₅ )), at least one of elemental phosphorus and elemental sulfur.

The ratio of Li ₂ S to P ₂ S ₅ in the Li—PS system glass and Li—PS system glass ceramic is a molar ratio of Li ₂ S: P ₂ S ₅ , preferably 65:35 to 85:15, more preferably 68:32 to 77:23. By setting the ratio of Li ₂ S to P ₂ S ₅ within this range, the lithium ion conductivity can be further increased. Specifically, the lithium ion conductivity can be preferably 1 × 10 ⁻⁴ S / cm or more, more preferably 1 × 10 ⁻³ S / cm or more. Although there is no particular upper limit, it is practical that it is 1 × 10 ⁻¹ S / cm or less.

Specific examples of the sulfide-based inorganic solid electrolyte include, for example, those using a raw material composition containing Li ₂ S and a sulfide of an element belonging to Group 13 to Group 15. it can. More specifically, Li ₂ S—P ₂ S ₅ , 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 —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-Al 2 S 3, Li 2 S-SiS 2 - _{_{_{_{l 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 S _{12 and the} like. Among them, Li ₂ S—P ₂ S ₅ , Li ₂ S—GeS ₂ —Ga ₂ S ₃ , Li ₂ S—SiS ₂ —P ₂ S ₅ , Li ₂ S—SiS ₂ —Li ₄ SiO ₄ , Li ₂ S—SiS ₂ —Li ₃ PO _4, Li ₂ S—LiI—Li ₂ O—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 , since a raw material composition of crystalline, amorphous or mixed crystalline and amorphous material composed of Li ₂ S—GeS ₂ —P ₂ S ₅ and Li ₁₀ GeP ₂ S ₁₂ has high lithium ion conductivity. preferable. Examples of a method for synthesizing a sulfide-based inorganic solid electrolyte material using such a raw material composition include an amorphization method. Examples of the amorphization method include a mechanical milling method and a melt quenching method, and among them, the mechanical milling method is preferable. 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 (O) and has ionic conductivity of a metal element belonging to Group 1 or Group 2 of the periodic table, And what has electronic insulation is 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 is particularly preferable. The upper limit is not particularly limited, but it is practical that it is 1 × 10 ⁻¹ S / cm or less.

As a specific compound example, 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 La _yb 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. Li _xc B _yc 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, and nc satisfies 0 ≦ nc ≦ 6); Li _xd (Al, Ga) _yd (Ti, Ge) _zd Si _ad P _md _Ond (xd satisfies 1 ≦ xd ≦ 3, yd Satisfies 0 ≦ yd ≦ 1, zd satisfies 0 ≦ zd ≦ 2, ad satisfies 0 ≦ ad ≦ 1, md satisfies 1 ≦ md ≦ 7, and 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 represents a divalent metal atom, D ^ee represents a halogen atom or two or more types of halogen atoms; Li _xf Si _yf O _zf (xf satisfies 1 ≦ xf ≦ 5, yf satisfies 0 <yf ≦ 3, and 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); LISICON Li 3.5} Zn 0.25 GeO with (Lithium super ionic conductor) type crystal structure ₄ ; La _0.55 Li _0.35 TiO ₃ having a perovskite-type crystal structure; LiTi ₂ P ₃ O ₁₂ having a NASICON (Natrium super ionic conductor) type crystal structure; Li _{1 + xh + yh} (Al, Ge) _xh (Ti, Ge) _2-xh Si _yh P _3-yh O ₁₂ (xh satisfies 0 ≦ xh ≦ 1 and yh satisfies 0 ≦ yh ≦ 1) And Li ₇ La ₃ Zr ₂ O ₁₂ (LLZ) having a garnet-type crystal structure.
Phosphorus compounds containing Li, P and O are also desirable. For example, lithium phosphate (Li ₃ PO ₄ ); LiPON obtained by substituting a part of oxygen of lithium phosphate with nitrogen; LiPOD ¹ (D ¹ is preferably Ti, V, Cr, Mn, Fe, Co, Ni, And at least one element selected from Cu, Zr, Nb, Mo, Ru, Ag, Ta, W, Pt, and Au.
Furthermore, LiA ¹ ON (A ¹ is one or more elements selected from Si, B, Ge, Al, C, and Ga) can be preferably used.
Among _them, (is as M bb, xb, yb, zb , mb and nb _{_{^{_{above.) LLT, Li xb La yb}}}} Zr zb M bb mb O nb, LLZ, Li 3 BO 3, Li 3 BO 3 -Li _{_{_{_{2 SO 4, Li xd (Al}}}} , Ga) yd (Ti, Ge) zd Si ad P md O nd (xd, yd, zd, ad, md and nd are as defined above.) is preferable.
These may be used alone or in combination of two or more.

The inorganic solid electrolyte is preferably a particle. The volume average particle diameter of the particulate inorganic solid electrolyte is not particularly limited, but is preferably 0.01 μm or more, and more preferably 0.1 μm or more. As an upper limit, it is preferable that it is 100 micrometers or less, and it is more preferable that it is 50 micrometers or less. In addition, the measurement of the volume average particle diameter of an inorganic solid electrolyte is performed in the following procedures. The inorganic solid electrolyte particles are prepared by diluting a 1 mass% dispersion in a 20 mL sample bottle using water (heptane in the case of a substance unstable to water). The diluted dispersion sample is irradiated with 1 kHz ultrasonic waves for 10 minutes and used immediately after that. Using this dispersion liquid sample, using a laser diffraction / scattering particle size distribution measuring device LA-920 (trade name, manufactured by HORIBA), data was acquired 50 times using a quartz cell for measurement at a temperature of 25 ° C., Obtain the volume average particle size. For other detailed conditions, the description of JISZ8828: 2013 “Particle Size Analysis—Dynamic Light Scattering Method” is referred to as necessary. Five samples are prepared for each level, and the average value is adopted.

The content of the solid component in the inorganic solid electrolyte layer of the inorganic solid electrolyte is 5% by mass or more at 100% by mass of the solid component when considering both the battery performance and the effect of reducing and maintaining the interface resistance. Is more preferable, 70% by mass or more is more preferable, and 90% by mass or more is particularly preferable. As an upper limit, it is preferable that it is 99.9 mass% or less from the same viewpoint, It is more preferable that it is 99.5 mass% or less, It is especially preferable that it is 99 mass% or less.
However, the content of the inorganic solid electrolyte in the positive electrode active material layer or the negative electrode active material layer is preferably such that the total content of the positive electrode active material or the negative electrode active material and the inorganic solid electrolyte is in the above range.
In the present specification, the solid component refers to a component that does not volatilize or evaporate when dried at 170 ° C. for 6 hours. Typically, it refers to components other than the dispersion medium described below.
An inorganic solid electrolyte may be used individually by 1 type, or may be used in combination of 2 or more type.

(binder)
In the all solid state secondary battery of the present invention, each layer (that is, a negative electrode active material layer, a solid electrolyte layer and / or a positive electrode active material layer, the same shall apply hereinafter) preferably contains a binder. The binder that can be used in the present invention is not particularly limited as long as it is an organic polymer.
The binder that can be used in the present invention is preferably a binder that is usually used as a binder for a positive electrode or a negative electrode of a battery material, and is not particularly limited. For example, a binder made of a resin described below is preferable.

Examples of the fluorine-containing resin include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), and a copolymer of polyvinylidene fluoride and hexafluoropropylene (PVdF-HFP).
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, polyisoprene, and polyisoprene latex.
Examples of the acrylic resin include poly (meth) methyl acrylate, poly (meth) ethyl acrylate, poly (meth) acrylate isopropyl, poly (meth) acrylate isobutyl, poly (meth) butyl acrylate, poly (meth) ) Hexyl acrylate, poly (meth) acrylate octyl, poly (meth) acrylate dodecyl, poly (meth) acrylate stearyl, poly (meth) acrylate 2-hydroxyethyl, poly (meth) acrylic acid, poly (meth) ) Benzyl acrylate, poly (meth) acrylate glycidyl, poly (meth) acrylate dimethylaminopropyl, and copolymers of monomers constituting these resins.
Examples of the urethane resin include polyurethane.
Further, copolymers with other vinyl monomers are also preferably used. Examples thereof include a poly (meth) methyl acrylate-polystyrene copolymer, a poly (meth) methyl acrylate-acrylonitrile copolymer, and a poly (meth) butyl acrylate-acrylonitrile-styrene copolymer. In the present invention, PVdF-HFP or HSBR is preferably used.
These may be used individually by 1 type, or may be used in combination of 2 or more type.

The polymer constituting the binder that can be used in the present invention preferably has a mass average molecular weight of 10,000 or more, more preferably 20,000 or more, and even more preferably 50,000 or more. As an upper limit, 1,000,000 or less is preferable, 200,000 or less is more preferable, and 100,000 or less is more preferable.
In the present invention, the molecular weight of the polymer means a mass average molecular weight unless otherwise specified. The mass average molecular weight can be measured as a molecular weight in terms of polystyrene by gel permeation chromatography (GPC). The measuring method is based on the measuring method in the examples described later. The eluent used is THF (tetrahydrofuran), and is selected from chloroform, NMP (N-methyl-2-pyrrolidone), and m-cresol / chloroform (manufactured by Shonan Wako Pure Chemical Industries, Ltd.). be able to.

In the all solid state secondary battery of the present invention, when there is a layer containing a binder, the content of the binder in the layer is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and 1% by mass or more. Is more preferable. As an upper limit, 10 mass% or less is preferable from a viewpoint of a battery characteristic, 8 mass% or less is more preferable, 6 mass% or less is further more preferable, and 5 mass% or less is especially preferable.
In the present invention, when each layer contains a binder, the mass ratio of the total mass (total amount) of the inorganic solid electrolyte and the active material to the mass of the binder [(mass of the inorganic solid electrolyte + mass of the active material) / mass of the binder] Is preferably in the range of 1,000 to 1. This ratio is more preferably 500 to 2, and further preferably 100 to 10.

(Lithium salt)
Each layer also preferably contains a lithium salt. The lithium salt is preferably a lithium salt usually used for an all-solid secondary battery, and is not particularly limited. For example, lithium salts described in paragraphs 0082 to 0085 of JP-A-2015-088486 are preferable.
The content of the lithium salt is preferably 0 part by mass or more and more preferably 5 parts by mass or more with respect to 100 parts by mass of the solid electrolyte. As an upper limit, 50 mass parts or less are preferable, and 20 mass parts or less are more preferable.

(Conductive aid)
Each layer, particularly the active material layer, may contain a conductive additive used for improving the electronic conductivity of the active material. As the conductive auxiliary agent, a general conductive auxiliary agent can be used. For example, graphites such as natural graphite and artificial graphite, carbon blacks such as acetylene black, ketjen black and furnace black, amorphous carbon such as needle coke, vapor grown carbon fiber or carbon nanotube, which are electron conductive materials Carbon fibers such as graphene, carbonaceous materials such as graphene or fullerene, metal powders such as copper and nickel, and metal fibers may be used, and conductive polymers such as polyaniline, polypyrrole, polythiophene, polyacetylene, and polyphenylene derivatives May be used. Moreover, 1 type of these may be used and 2 or more types may be used.
In the all solid state secondary battery of the present invention, when there is a layer containing a conductive assistant, the content of the conductive assistant in the layer is not particularly limited and can be appropriately set in consideration of battery characteristics and the like.

(Dispersant)
In the present invention, it is preferable to contain a dispersant in any of the positive electrode active material layer, the solid electrolyte layer, and the negative electrode active material layer. By adding a dispersant, even when the concentration of either the electrode active material or the inorganic solid electrolyte is high, aggregation can be suppressed, and a uniform electrode layer (active material layer) and solid electrolyte layer can be formed. It is effective for improvement. As the dispersant, those usually used for all-solid secondary batteries can be appropriately selected and used. For example, it consists of a low molecule or oligomer having a molecular weight of 200 or more and less than 3000, and contains the functional group represented by the functional group (I) and an alkyl group having 8 or more carbon atoms or an aryl group having 10 or more carbon atoms in the same molecule. Those are preferred.
Functional group (I): acidic group, group having basic nitrogen atom, (meth) acryl group, (meth) acrylamide group, alkoxysilyl group, epoxy group, oxetanyl group, isocyanate group, cyano group, thiol group and hydroxy Group (an acidic group, a group having a basic nitrogen atom, an alkoxysilyl group, a cyano group, a thiol group, and a hydroxy group are preferable, and a carboxy group, a sulfonic acid group, a cyano group, an amino group, and a hydroxy group are more preferable).
In the all solid state secondary battery of the present invention, when there is a layer containing a dispersant, the content of the dispersant in the layer is not particularly limited and can be appropriately set in consideration of battery characteristics and the like.

(Positive electrode active material)
Next, the positive electrode active material used for the positive electrode active material layer 4 of the all-solid-state secondary battery of the present invention will be described. The positive electrode active material is preferably one that can reversibly insert and / or release lithium ions. The material is not particularly limited, and may be a transition metal oxide or an element that can be complexed with Li such as sulfur. Among them, as the positive electrode active material, it is preferable to use a transition metal oxide, and a transition metal oxide having a transition metal element M ^a (one or more elements selected from Co, Ni, Fe, Mn, Cu, and V). More preferred. In addition, this transition metal oxide includes an element M ^b (an element of the first (Ia) group of the metal periodic table other than lithium, an element of the second (IIa) group, Al, Ga, In, Ge, Sn, Pb, Elements such as Sb, Bi, Si, P, and B) may be mixed. The mixing amount, 0 ~ 30 mol% relative to the amount of the transition metal element ^{M a} is preferable. Those synthesized by mixing so that the molar ratio of Li / Ma is 0.3 to 2.2 are more preferable.
Specific examples of the transition metal oxide include (MA) a transition metal oxide having a layered rock salt structure, (MB) a transition metal oxide having a spinel structure, (MC) a lithium-containing transition metal phosphate compound, (MD And lithium-containing transition metal halide phosphate compounds, (ME) lithium-containing transition metal silicate compounds, and the like.

(MA) As specific examples of the transition metal oxide having a layered rock salt structure, LiCoO ₂ (lithium cobaltate [LCO]), LiNi ₂ O ₂ (lithium nickelate), LiNi _0.85 Co _0.10 Al _{0. 05} O ₂ (nickel cobalt lithium aluminum oxide [NCA]), LiNi _1/3 Co _1/3 Mn _1/3 O ₂ (nickel manganese lithium cobalt oxide [NMC]), LiNi _0.5 Mn _0.5 O ₂ ( Lithium manganese nickelate).
Specific examples of the transition metal oxide having an (MB) spinel structure include 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. .
Examples of (MC) lithium-containing transition metal phosphate compounds 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 , LiCoPO _{4 and the} like. And monoclinic Nasicon type vanadium phosphate salts such as Li ₃ V ₂ (PO ₄ ) ₃ (vanadium lithium phosphate).
The (MD) 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, Li 2 CoPO ₄ F Cobalt fluorophosphates such as
Examples of the (ME) lithium-containing transition metal silicate compound include Li ₂ FeSiO ₄ , Li ₂ MnSiO ₄ , Li ₂ CoSiO _{4, and the} like.
In the present invention, a transition metal oxide having a (MA) layered rock salt structure is preferable, and LCO is more preferable.

The shape of the positive electrode active material is not particularly limited, but is preferably particulate. The volume average particle diameter (sphere conversion average particle diameter) of the positive electrode active material is not particularly limited. For example, the thickness can be 0.1 to 50 μm. In order to make the positive electrode active material have a predetermined particle size, an ordinary pulverizer or classifier may be used. 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. The volume average particle diameter (sphere-converted average particle diameter) of the positive electrode active material particles can be measured using a laser diffraction / scattering particle size distribution analyzer LA-920 (trade name, manufactured by HORIBA).

The content of the positive electrode active material in the positive electrode active material layer is not particularly limited, preferably 10 to 95% by mass, more preferably 20 to 90% by mass, further preferably 30 to 85% by mass, and 50 to 80% by mass. Particularly preferred.

When forming the positive electrode active material layer, the mass (mg) (weight per unit area) 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 arbitrarily determined according to the designed battery capacity.
The positive electrode active materials may be used alone or in combination of two or more.

(Negative electrode active material)
Next, the negative electrode active material used for the negative electrode active material layer of the all solid state secondary battery of the present invention will be described. The negative electrode active material is preferably one that can reversibly insert and / or release lithium ions. The material is not particularly limited, and is a carbonaceous material, a metal oxide such as tin oxide or silicon oxide, a metal composite oxide, a lithium alloy such as lithium alone or a lithium aluminum alloy, and a lithium such as Sn, Si or In. And metals capable of forming an alloy. Among these, a carbonaceous material or a lithium composite oxide is preferably used from the viewpoint of reliability. In addition, the metal composite oxide is preferably capable of inserting and extracting lithium. The material is not particularly limited, but preferably contains titanium and / or lithium as a constituent component from the viewpoint of high current density charge / discharge characteristics.

The carbonaceous material used as the negative electrode active material is a material substantially made of carbon. For example, various synthetics such as petroleum pitch, carbon black such as acetylene black (AB), graphite (natural graphite, artificial graphite such as vapor-grown graphite), PAN (polyacrylonitrile) resin or furfuryl alcohol resin, etc. The carbonaceous material which baked resin can be mentioned. Further, various carbon fibers such as PAN-based carbon fiber, cellulose-based carbon fiber, pitch-based carbon fiber, vapor-grown carbon fiber, dehydrated PVA (polyvinyl alcohol) -based carbon fiber, lignin carbon fiber, glassy carbon fiber, activated carbon fiber, etc. And mesophase microspheres, graphite whiskers, flat graphite and the like.

These carbonaceous materials can be divided into non-graphitizable carbonaceous materials and graphite-based carbonaceous materials according to the degree of graphitization. The carbonaceous material preferably has a face spacing or density and crystallite size described in JP-A-62-222066, JP-A-2-6856, and 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, or the like is used. You can also.

As the metal oxide and metal composite oxide applied as the negative electrode active material, an amorphous oxide is particularly preferable, and chalcogenite, which is a reaction product of a metal element and an element of Group 16 of the periodic table, is also preferably used. It is done. The term “amorphous” as used herein means an X-ray diffraction method using CuKα rays, which has a broad scattering band having a peak in the region of 20 ° to 40 ° in terms of 2θ, and is a crystalline diffraction line. You may have. The strongest intensity of crystalline diffraction lines seen from 2 ° to 40 ° to 70 ° is 100 times the diffraction line intensity at the peak of the broad scattering band seen from 2 ° to 20 °. It is preferable that it is 5 times or less, and it is particularly preferable not to have a crystalline diffraction line.

Among the compound group consisting of the amorphous oxide and the chalcogenide, the amorphous oxide of the metalloid element and the chalcogenide are more preferable, and elements of Groups 13 (IIIB) to 15 (VB) of the periodic table, Al , Ga, Si, Sn, Ge, Pb, Sb, Bi alone or in combination of two or more thereof, and chalcogenide are particularly preferable. 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 i ₂ O ₃ , Bi ₂ O ₄ , SnSiO ₃ , GeS, SnS, SnS ₂ , PbS, PbS ₂ , Sb ₂ S ₃ , Sb ₂ S ₅ , SnSiS ₃ is preferred. Moreover, these may be a complex oxide with lithium oxide, for example, Li ₂ SnO ₂ .

It is also preferable that the negative electrode active material contains a titanium atom. More specifically, Li ₄ Ti ₅ O ₁₂ (lithium titanate [LTO]) is excellent in rapid charge / discharge characteristics due to small volume fluctuations during occlusion and release of lithium ions, and the deterioration of the electrode is suppressed, and the lithium ion secondary This is preferable in that the battery life can be improved.

In the present invention, hard carbon or graphite is preferably used, and graphite is more preferably used. In the present invention, the carbonaceous materials may be used singly or in combination of two or more.

The shape of the negative electrode active material is not particularly limited, but is preferably particulate. The average particle size of the negative electrode active material is preferably 0.1 to 60 μm. In order to obtain a predetermined particle size, an ordinary pulverizer or classifier is used. For example, a mortar, a ball mill, a sand mill, a vibrating ball mill, a satellite ball mill, a planetary ball mill, a swirling air flow type jet mill or a sieve is preferably used. When pulverizing, wet pulverization in the presence of water or an organic solvent such as methanol can be performed as necessary. In order to obtain a desired particle diameter, classification is preferably performed. The classification method is not particularly limited, and a sieve, an air classifier, or the like can be used as necessary. Classification can be used both dry and wet. The average particle diameter of the negative electrode active material particles can be measured by the same method as the above-described method for measuring the volume average particle diameter of the positive electrode active material.

The content of the negative electrode active material in the negative electrode active material layer is not particularly limited, is preferably 10 to 95% by mass, more preferably 20 to 90% by mass, and more preferably 30 to 85% by mass. More preferably, it is 40 to 80% by mass.

When the negative electrode active material layer is formed, the mass (mg) (weight per unit area) of the negative electrode active material per unit area (cm ² ) of the negative electrode active material layer is not particularly limited. It can be arbitrarily determined according to the designed battery capacity.
The said negative electrode active material may be used individually by 1 type, or may be used in combination of 2 or more type.

In the present invention, a functional layer or a member is appropriately interposed or disposed between or outside each of the negative electrode conductive film, the negative electrode active material layer, the solid electrolyte layer, the positive electrode active material layer, and the positive electrode conductive film. May be. Moreover, each said layer and electrical power collector may be comprised by the single layer, or may be comprised by the multilayer.

[Case]
The basic structure of the all-solid-state secondary battery can be manufactured by arranging each of the above layers. Depending on the application, it may be used as an all-solid secondary battery as it is, but in order to form a dry battery, it is further enclosed in a suitable housing. The housing may be metallic or made of resin (plastic). When using a metallic thing, the thing made from an aluminum alloy or stainless steel can be mentioned, for example. The metallic housing is preferably divided into a positive-side housing and a negative-side housing, and electrically connected to the positive current collector and the negative current collector, respectively. The casing on the positive electrode side and the casing on the negative electrode side are preferably joined and integrated through a gasket for preventing a short circuit.

[Electrode sheet for all-solid-state secondary battery]
The electrode sheet for an all-solid-state secondary battery of the present invention (hereinafter simply referred to as “electrode sheet of the present invention”) is an electrode sheet having a conductive film and an active material layer in this order on a current collector, It can use suitably for the all-solid-state secondary battery of this invention.
This electrode sheet is usually a sheet having a current collector and an active material layer provided with a conductive film, but an embodiment having a current collector with a conductive film, an active material layer and a solid electrolyte layer in this order, and The aspect which has a collector with an electroconductive film, an active material layer, a solid electrolyte layer, and an active material layer in this order is also included.
The configuration and the layer thickness of each layer constituting the electrode sheet are the same as the configuration and the layer thickness of each layer described in the all solid state secondary battery of the present invention.

[Manufacture of all-solid-state secondary battery and electrode sheet for all-solid-state secondary battery]
The all-solid-state secondary battery and the electrode sheet for the all-solid-state secondary battery can be produced by a conventional method. This will be described in detail below.
The all-solid-state secondary battery and the all-solid-state secondary battery electrode sheet of the present invention form a conductive film on a metal foil serving as a current collector, and then apply the solid electrolyte composition to form a coating film. It can be manufactured by forming.
For example, a positive electrode conductive film is formed on a metal foil that is a positive electrode current collector, a positive electrode material (positive electrode composition) is applied to form a positive electrode active material layer, and a positive electrode sheet for an all-solid-state secondary battery is formed. Make it. Next, a solid electrolyte composition for forming a solid electrolyte layer is applied on the positive electrode active material layer of the sheet to form a solid electrolyte layer. Further, a negative electrode material (negative electrode composition) is applied on the solid electrolyte layer to form a negative electrode active material layer. A solid electrolyte layer was sandwiched between the positive electrode active material layer and the negative electrode active material layer by superimposing a negative electrode current collector (metal foil) provided with a negative electrode conductive film as necessary on the negative electrode active material layer. An all-solid secondary battery having a structure can be obtained. If necessary, this can be enclosed in a housing to obtain a desired all-solid secondary battery.
Further, by reversely forming each layer, a negative electrode active material layer, a solid electrolyte layer, and a positive electrode active material layer are formed on the negative electrode current collector, and the positive electrode current collector with the positive electrode conductive film is stacked, A solid secondary battery can also be manufactured.

Another method includes the following method. That is, a positive electrode sheet for an all-solid secondary battery is produced as described above. Further, a negative electrode conductive film is formed on a metal foil as a negative electrode current collector, and a negative electrode material (a composition for negative electrode layer) is applied to form a negative electrode active material layer. A sheet is produced. Next, a solid electrolyte layer is formed on one of the active material layers of these sheets as described above. Furthermore, the other of the positive electrode sheet for an all solid secondary battery and the negative electrode sheet for an all solid secondary battery is laminated on the solid electrolyte layer so that the solid electrolyte layer and the active material layer are in contact with each other. In this way, an all-solid secondary battery can be manufactured.
Another method includes the following method. That is, as described above, a positive electrode sheet for an all-solid secondary battery and a negative electrode sheet for an all-solid secondary battery are produced. Separately, a solid electrolyte composition is applied to a substrate to produce a solid electrolyte sheet composed of a solid electrolyte layer. Furthermore, it laminates | stacks so that a solid electrolyte sheet may be pinched | interposed with the positive electrode sheet for all-solid-state secondary batteries, and the negative electrode sheet for all-solid-state secondary batteries. In this way, an all-solid secondary battery can be manufactured.

An all-solid-state secondary battery can also be manufactured by a combination of the above forming methods. For example, as described above, a positive electrode sheet for an all-solid secondary battery, a negative electrode sheet for an all-solid secondary battery, and a solid electrolyte sheet are respectively produced. Then, after laminating the solid electrolyte layer peeled off from the base material on the negative electrode sheet for an all solid secondary battery, an all solid secondary battery can be produced by pasting the positive electrode sheet for the all solid secondary battery. it can. In this method, the solid electrolyte layer can be laminated on the positive electrode sheet for an all-solid secondary battery, and bonded to the negative electrode sheet for an all-solid secondary battery.
In the said manufacturing method, it can replace with the said negative electrode sheet for all-solid-state secondary batteries, and can also use the sheet | seat provided with the negative electrode electrical power collector and the negative electrode active material layer adjacent to this.

Each process (process) in the said manufacturing method is demonstrated concretely.
(Roughening of current collector)
The positive electrode current collector used in the above production method is provided with a positive electrode conductive film on the surface thereof. The negative electrode current collector is provided with a negative electrode conductive film on the surface thereof as necessary. At this time, the surface of the current collector is roughened as necessary, and the current collector is set to the surface form.
The method for roughening the surface of the current collector is not particularly limited, and a normal method can be employed. For example, when producing a current collector by rolling, a method of transferring the surface state of a rolling roll can be mentioned. Further, a method of roughening the surface of the current collector by a sandblast method or the like can be mentioned. In this case, the surface form can be appropriately set according to the conditions of the material, shape, particle size, spraying pressure, spraying speed, and spraying time of the sand used. Furthermore, a method of subjecting the current collector to an electrochemical surface roughening treatment (also referred to as an electrolytic surface roughening treatment) is also included. In the present invention, electrolytic surface roughening is preferred.

Hereinafter, an electrolytic surface-roughening method will be described by taking a current collector made of aluminum as an example. However, the surface form of the current collector can be appropriately set by subjecting the current collector formed of a material other than aluminum to the same electrolytic surface roughening.

The aluminum forming the current collector subjected to the electrolytic surface roughening treatment is not particularly limited, and a normal aluminum foil can be used. The aluminum foil is a metal foil mainly composed of aluminum. For example, alloy numbers 1085, 1N30, and 3003 described in Japanese Industrial Standard (JIS Standard) H4000 can be used.
The thickness of the aluminum foil may be the same as the thickness of the current collector, but is preferably 100 μm or less, preferably 5 to 80 μm, and more preferably 10 to 50 μm.

The electrochemical roughening treatment of the aluminum foil may include various treatments or steps other than the electrochemical roughening treatment as long as it includes at least the electrochemical roughening treatment.
As an electrochemical surface-roughening method for obtaining the above surface form, for example, if necessary, an aluminum foil is subjected to an alkali etching treatment, followed by an acid desmutting treatment and an electrochemical surface-roughening treatment using an electrolytic solution in sequence. Examples of the method include a method of performing an alkali etching treatment, an acid desmutting treatment on an aluminum foil, and an electrochemical surface roughening treatment using different electrolytic solutions a plurality of times, but the present invention is not limited thereto. In these methods, after the electrochemical surface roughening treatment, an alkali etching treatment and an acid desmutting treatment may be further performed.
Hereinafter, each process of the surface treatment will be described in detail.

-Electrochemical roughening-
In the electrochemical surface roughening treatment, an electrolytic solution used for the electrochemical surface roughening treatment using a normal alternating current can be used. Among them, it is preferable to use an electrolytic solution mainly composed of hydrochloric acid or nitric acid because the above-described surface shape can be easily obtained.

Electrolytic surface roughening can be performed according to, for example, the electrochemical grain method (electrolytic grain method) described in Japanese Patent Publication No. 48-28123 and British Patent No. 896,563. This electrolytic grain method uses a sinusoidal alternating current, but it may be performed using a special waveform as described in JP-A-52-58602. Further, the waveform described in JP-A-3-79799 can also be used. Further, JP-A-55-158298, JP-A-56-28898, JP-A-52-58602, JP-A-52-152302, JP-A-54-85802, JP-A-60-190392, JP-A-58-120531, JP-A-63-176187, JP-A-1-5889, JP-A-1-280590, JP-A-1-118489, JP-A-1-148592, and JP-A-1-17896. JP-A-1-188315, JP-A-1-1549797, JP-A-2-235794, JP-A-3-260100, JP-A-3-253600, JP-A-4-72079, JP-A-4-72098, The methods described in JP-A-3-267400 and JP-A-1-141094 can also be applied. In addition to the above, it is also possible to perform electrolysis using an alternating current having a special frequency that has been proposed as a method of manufacturing an electrolytic capacitor. For example, it is described in JP-A-58-207400, US Pat. Nos. 4,276,129 and 4,676,879.

Various electrolyzers and power sources have been proposed. US Pat. No. 4,203,637, JP-A-56-123400, JP-A-57-59770, JP-A-53-12738, JP-A-53. -32821, JP-A 53-32822, JP-A 53-32823, JP-A 55-122896, JP-A 55-13284, JP-A 62-127500, JP-A-1-52100 JP-A-1-52098, JP-A-60-67700, JP-A-1-230800, JP-A-3-257199 and the like can be used. Further, JP-A-52-58602, JP-A-52-152302, JP-A-53-12738, JP-A-53-12739, JP-A-53-32821, JP-A-53-32222, JP 53-32833, JP 53-32824, JP 53-32825, JP 54-85802, JP 55-122896, JP 55-13284, JP 48-28123, JP-B-51-7081, JP-A-52-13338, JP-A-52-133840, JP-A-52-133844, JP-A-52-133845, JP-A-53- Nos. 149135 and 54-146234 can also be used.

As an acidic solution which is an electrolytic solution, in addition to nitric acid and hydrochloric acid, U.S. Pat. Nos. 4,671,859, 4,661,219, 4,618,405, 4,600, 482, 4,566,960, 4,566,958, 4,566,959, 4,416,972, 4,374,710, The electrolyte solution described in each specification of 4,336,113 and 4,184,932 can also be used.

The concentration of the acidic solution is preferably 0.5 to 2.5% by mass, but it is particularly preferably 0.7 to 2.0% by mass in consideration of use in the smut removal treatment. The liquid temperature is preferably 20 to 80 ° C., more preferably 30 to 60 ° C.

An aqueous solution mainly composed of hydrochloric acid or nitric acid is an aqueous solution of hydrochloric acid or nitric acid having a concentration of 1 to 100 g / L. At least one of the hydrochloric acid compounds having hydrochloric acid ions can be used by adding in a range from 1 g / L to saturation. Moreover, the metal contained in aluminum alloys, such as iron, copper, manganese, nickel, titanium, magnesium, a silica, may melt | dissolve in the aqueous solution which has hydrochloric acid or nitric acid as a main component. It is preferable to use a solution obtained by adding aluminum chloride, aluminum nitrate or the like to an aqueous solution of hydrochloric acid or nitric acid having a concentration of 0.5 to 2% by mass so that aluminum ions are 3 to 50 g / L.

Furthermore, by adding and using a compound capable of forming a complex with Cu, uniform graining is possible even for an aluminum foil containing a large amount of Cu. Examples of the compound capable of forming a complex with Cu include ammonia; hydrogen atom of ammonia such as methylamine, ethylamine, dimethylamine, diethylamine, trimethylamine, cyclohexylamine, triethanolamine, triisopropanolamine, EDTA (ethylenediaminetetraacetic acid). And amines obtained by substituting with a hydrocarbon group (aliphatic, aromatic, etc.); metal carbonates such as sodium carbonate, potassium carbonate, potassium hydrogen carbonate and the like. In addition, ammonium salts such as ammonium nitrate, ammonium chloride, ammonium sulfate, ammonium phosphate, and ammonium carbonate are also included. The temperature is preferably 10 to 60 ° C, more preferably 20 to 50 ° C.

The AC power wave used for the electrochemical surface roughening treatment is not particularly limited, and a sine wave, a rectangular wave, a trapezoidal wave, a triangular wave or the like is used, but a rectangular wave or a trapezoidal wave is preferable, and a trapezoidal wave is particularly preferable. In this trapezoidal wave, the time (TP) until the current reaches a peak from zero is preferably 0.5 to 3 msec. If it is less than 0.5 msec, processing irregularities such as chatter marks that occur perpendicular to the traveling direction of the aluminum foil are likely to occur. When TP exceeds 3 msec, especially when a nitric acid electrolyte is used, it is easily affected by trace components in the electrolyte typified by ammonium ions and the like that spontaneously increase by electrolytic treatment, and uniform graining is performed. It becomes hard to be broken.

A trapezoidal wave AC duty ratio of 1: 2 to 2: 1 can be used. However, as described in Japanese Patent Laid-Open No. 5-195300, in an indirect power feeding method that does not use a conductor roll for aluminum. A duty ratio of 1: 1 is preferable. A trapezoidal AC frequency of 0.1 to 120 Hz can be used, but 50 to 70 Hz is preferable in terms of equipment. When the frequency is lower than 50 Hz, the carbon electrode of the main electrode is easily dissolved, and when the frequency is higher than 70 Hz, it is easily affected by an inductance component on the power supply circuit, and the power supply cost is increased.

One or more AC power supplies can be connected to the electrolytic cell. For the purpose of controlling the current ratio between the anode and cathode of alternating current applied to the aluminum foil facing the main electrode, uniform graining, and dissolving the carbon of the main electrode, an auxiliary anode is installed, It is preferable to divert part of the alternating current. An anodic reaction that acts on the aluminum foil facing the main electrode by diverting a part of the current value as a direct current to an auxiliary anode provided in a separate tank from the two main electrodes via a rectifier or switching element It is possible to control the ratio between the current value for the current and the current value for the cathode reaction. On the aluminum foil facing the main electrode, the ratio of the amount of electricity involved in the cathode reaction and the anodic reaction (cathode amount of electricity / anode amount of electricity) is preferably 0.3 to 0.95.

As the electrolytic cell, an electrolytic cell usually used for surface treatment such as a vertical type, a flat type, and a radial type can be used. However, a radial type electrolytic cell as described in JP-A-5-195300 is particularly preferable. preferable. The electrolytic solution passing through the electrolytic cell may be parallel to the traveling direction of the aluminum web or may be a counter.

(Nitric acid electrolysis)
In the present invention, the arithmetic average roughness Ra and the number of recesses are set in the above range by electrochemical surface roughening treatment (hereinafter also referred to as “nitric acid electrolysis”) using an electrolytic solution mainly composed of nitric acid. be able to.
Here, since nitric acid electrolysis enables formation of a uniform and high-density recess, alternating current is used, the peak current density (peak value of current density) is set to 15 A / dm ² or more, and the average current density (average value). ) Is preferably 13 A / dm ² or more, and the amount of electricity is preferably 100 c / dm ² or more. The peak current density is preferably 100 A / dm ² or less, and more preferably 68 A / dm ² or less. Further, the average current density is preferably 40 A / dm ² or less, and more preferably 31.0 A / dm ² or less. The amount of electricity is preferably 400 c / dm ² or less.
The concentration or temperature of the electrolytic solution in nitric acid electrolysis is not particularly limited, and electrolysis is performed at 30 to 60 ° C. using a nitric acid electrolytic solution having a high concentration, for example, a nitric acid concentration of 15 to 35% by mass, or a nitric acid concentration of 0.1%. Electrolysis can be carried out at a high temperature, for example, at 80 ° C. or higher, using a 7-2 mass% nitric acid electrolyte.

(Hydrochloric acid electrolysis)
In the present invention, the arithmetic average roughness Ra and the number of recesses are set in the above range also by electrochemical surface roughening treatment (hereinafter, also referred to as “hydrochloric acid electrolysis”) using an electrolytic solution mainly composed of hydrochloric acid. can do.
Here, in hydrochloric acid electrolysis, for the reason that uniform and high-density recesses can be formed, an alternating current is used, the peak current density is 30 A / dm ² or more, the average current density is 13 A / dm ² or more, and The electrolytic treatment is preferably performed under the condition that the amount of electricity is 150 c / dm ² or more. The peak current density is preferably 100 A / dm ² or less, the average current density is preferably 40 A / dm ² or less, and the amount of electricity is preferably 400 c / dm ² or less.

-Desmut treatment-
After the electrolytic surface roughening treatment or the alkali etching treatment, pickling (desmut treatment) is preferably performed to remove dirt (smut) remaining on the surface.
Examples of the acid used include nitric acid, sulfuric acid, phosphoric acid, chromic acid, hydrofluoric acid, and borohydrofluoric acid. The desmutting treatment is performed, for example, by bringing the aluminum foil into contact with an acidic solution (containing aluminum ions of 0.01 to 5% by mass) having a concentration of 0.5 to 30% by mass such as hydrochloric acid, nitric acid, and sulfuric acid. . Examples of the method of bringing the aluminum foil into contact with the acidic solution include a method of passing the aluminum foil through the acidic solution bath, a method of immersing the aluminum foil in the acidic solution bath, and spraying the acidic solution onto the surface of the aluminum foil. A method is mentioned. In the desmutting treatment, the acid solution is mainly composed of an aqueous solution mainly composed of nitric acid or an aqueous solution mainly composed of hydrochloric acid discharged in the above-described electrolytic surface-roughening treatment, or sulfuric acid discharged in an anodic oxidation process described later. It is possible to use a waste solution of an aqueous solution. The temperature of the desmut treatment is preferably 25 to 90 ° C. The processing time is preferably 1 to 180 seconds. Aluminum and aluminum alloy components may be dissolved in the acidic solution used for the desmut treatment.

-Other processing-
In the electrochemical surface roughening treatment method, an alkali etching treatment can be performed before and / or after the electrolytic surface roughening treatment. The alkali etching treatment is a treatment for dissolving the surface layer by bringing the aluminum foil into contact with an alkali solution. This treatment is performed for the purpose of removing the rolling oil, dirt, natural oxide film, etc. on the surface of the aluminum foil or dissolving the smut generated in the acidic electrolyte. The alkali etching treatment can be performed by applying normal conditions without particular limitation.
In the electrochemical surface roughening treatment method, the aluminum foil treated as described above can be anodized as necessary from the viewpoint of preventing corrosion. The anodizing treatment can be performed by a usual method and conditions. Moreover, the sealing process which seals the micropore which exists in an anodic oxide film can also be performed as needed. The sealing treatment can be performed by a usual method and conditions.
A normal method and conditions can be adopted for each treatment in the electrochemical surface roughening treatment method. For example, each process (method or condition) described in JP-A-2015-53240 can be referred to as appropriate.

-Washing treatment-
In the present invention, it is preferable to carry out water washing after completion of the above-described processes. For washing, pure water, well water, tap water, or the like can be used. A nip device may be used to prevent the processing liquid from being brought into the next process.

(Formation of conductive film)
The method for forming the conductive film on the surface of the current collector having the above surface form is not particularly limited. For example, chemical vapor deposition (CVD), physical vapor deposition (BVD), sputtering using the above-described conductive particles. Examples include a deposition method such as phosphorus, a plating method such as electroplating, and an application (printing) method in which a coating composition in which the above-described conductive particles are dispersed in a binder is applied (printed) to the surface of the current collector and dried. It is done. Among these, a method of forming a conductive film by the vapor deposition method or the coating method using the above-described conductive particles is preferable.

(Formation of each layer (film formation))
In order to form each layer of the positive electrode active material layer 4, the solid electrolyte layer 3, and the negative electrode active material layer 2, a solid electrolyte composition is preferably used.
In the present invention, the solid electrolyte composition for forming the solid electrolyte layer contains an inorganic solid electrolyte. Moreover, it is preferable that the composition for positive electrodes for forming a positive electrode active material layer contains a positive electrode active material, and also contains an inorganic solid electrolyte. Similarly, the negative electrode composition for forming the negative electrode active material layer preferably contains a negative electrode active material and further contains an inorganic solid electrolyte.
In the present invention, when the positive electrode composition and the negative electrode composition contain an inorganic solid electrolyte, the solid electrolyte composition for forming the solid electrolyte layer, the positive electrode composition, and the negative electrode composition are combined. Sometimes referred to as a solid electrolyte composition.

The solid electrolyte composition contains an inorganic solid electrolyte, and may contain a positive electrode active material or a negative electrode active material, and further a binder, a lithium salt, a conductive additive, a dispersant, and a dispersion medium.
The inorganic solid electrolyte, the positive electrode active material, the negative electrode active material, the binder, the lithium salt, the conductive assistant and the dispersant are as described above.

Examples of the dispersion medium include the following, which are preferable.
The dispersion medium only needs to disperse each of the above components, and examples thereof include various organic solvents. Specific examples of the dispersion medium include the following.
Examples of the alcohol compound solvent include methyl alcohol, ethyl alcohol, 1-propyl alcohol, 2-propyl alcohol, 2-butanol, ethylene glycol, propylene glycol, glycerin, 1,6-hexanediol, cyclohexanediol, sorbitol, xylitol, Examples include 2-methyl-2,4-pentanediol, 1,3-butanediol, and 1,4-butanediol.
Examples of ether compound solvents 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 monomethyl ether, dipropylene. Glycol monomethyl ether, tripropylene glycol monomethyl ether, diethylene glycol monobutyl ether, diethylene glycol monobutyl ether, etc.), dialkyl ethers (dimethyl ether, diethyl ether, diisopropyl ether, dibutyl ether, etc.), cyclic ethers (tetrahydrofuran, geo Sun (1,2-, 1,3- and each isomer 1,4), etc.), and the like.
Examples of the amide compound solvent include N, N-dimethylformamide, N-methyl-2-pyrrolidone, 2-pyrrolidinone, 1,3-dimethyl-2-imidazolidinone, 2-pyrrolidinone, ε-caprolactam, formamide, N -Methylformamide, acetamide, N-methylacetamide, N, N-dimethylacetamide, N-methylpropanamide, hexamethylphosphoric triamide and the like.
Examples of the amino compound solvent include triethylamine, diisopropylethylamine, tributylamine and the like.
Examples of the ketone compound solvent include acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone.
Examples of the aromatic compound solvent include benzene, toluene, xylene and the like.
Examples of the aliphatic compound solvent include hexane, heptane, octane, decane, and the like.
Examples of the nitrile compound solvent include acetonitrile, propyronitrile, isobutyronitrile, and the like.
Examples of the ester compound solvent include ethyl acetate, butyl acetate, propyl acetate, butyl butyrate, and butyl pentanoate.
Examples of the non-aqueous dispersion medium include the above aromatic compound solvents and aliphatic compound solvents.

In the present invention, among them, ether compound solvents, aliphatic compound solvents, nitrile compound solvents, and aromatic compound solvents are preferable, and heptane, octane, nonane, toluene, and xylene are more preferable.
The dispersion medium preferably has a boiling point of 50 ° C. or higher, more preferably 70 ° C. or higher, at normal pressure (1 atm). The upper limit is preferably 250 ° C. or lower, and more preferably 220 ° C. or lower.
The content of the dispersion medium in the solid electrolyte composition is preferably 10 to 95 parts by weight, more preferably 15 to 90 parts by weight, and particularly preferably 20 to 85 parts by weight with respect to 100 parts by weight as a whole.
The said dispersion medium may be used individually by 1 type, or may be used in combination of 2 or more type.

The solid electrolyte composition of the present invention can be produced by mixing an inorganic solid electrolyte, a binder and a dispersion medium, and if necessary, other components using, for example, various mixers.

The method for applying the solid electrolyte composition is not particularly limited, and can be appropriately selected. Examples thereof include coating (preferably wet coating), spray coating, spin coating coating, dip coating, slit coating, stripe coating, and bar coating coating.
At this time, the solid electrolyte composition may be dried after being applied, or may be dried after being applied in multiple layers. The drying temperature is not particularly limited. The lower limit is preferably 30 ° C or higher, more preferably 60 ° C or higher, and the upper limit is preferably 300 ° C or lower, more preferably 250 ° C or lower. By heating in such a temperature range, a dispersion medium can be removed and it can be set as a solid state.

It is preferable to pressurize each layer or all-solid secondary battery after producing the applied solid electrolyte composition or all-solid-state secondary battery. Moreover, it may pressurize in the state which laminated | stacked each layer. An example of the pressurizing method is a hydraulic cylinder press. The applied pressure is not particularly limited and is generally preferably in the range of 50 to 1500 MPa. By this pressurization, in the solid electrolyte layer or the like, voids derived from the particle interface such as the inorganic solid electrolyte can be eliminated and the inorganic solid electrolyte or the like can be densely filled.
Moreover, you may heat the apply | coated solid electrolyte composition simultaneously with pressurization. The heating temperature is not particularly limited, and is generally in the range of 30 to 300 ° C. It is also possible to press at a temperature higher than the glass transition temperature of the inorganic solid electrolyte. On the other hand, when the inorganic solid electrolyte and the binder coexist, pressing can be performed at a temperature higher than the glass transition temperature of the binder. However, in general, the temperature does not exceed the melting point of the binder.
The pressurization may be performed in a state where the coating solvent or the dispersion medium is previously dried, or may be performed in a state where the solvent or the dispersion medium remains.

The atmosphere during pressurization is not particularly limited, and may be any of the following: air, dry air (dew point of −20 ° C. or lower), inert gas (for example, argon gas, helium gas, nitrogen gas).
The pressing time may be a high pressure in a short time (for example, within several hours), or a medium pressure may be applied for a long time (1 day or more). In the case of an all-solid-state secondary battery other than the electrode sheet or the solid electrolyte sheet for an all-solid-state secondary battery, for example, in order to keep applying moderate pressure, all-solid-state secondary battery restraints (screw tightening pressure, etc.) It can also be used.
The pressing pressure may be uniform or different with respect to the pressed part such as the sheet surface.
The pressing pressure can be changed according to the area or film thickness of the pressed part. Also, the same part can be changed stepwise with different pressures.
The press surface may be smooth or roughened.

(Initialization)
The all solid state secondary battery manufactured as described above is preferably initialized after manufacture or before use. The initialization is not particularly limited, and can be performed, for example, by performing initial charging / discharging in a state where the press pressure is increased, and then releasing the pressure until the general use pressure of the all-solid secondary battery is reached.

[Use of all-solid secondary batteries]
The all solid state secondary battery of the present invention can be applied to various uses. Although there is no particular limitation on the application mode, for example, when installed in an electronic device, a notebook computer, a pen input personal computer, a mobile personal computer, an electronic book player, a mobile phone, a cordless phone, a pager, a handy terminal, a mobile fax machine, a mobile phone Copy, portable printer, headphone stereo, video movie, LCD TV, handy cleaner, portable CD, minidisc, electric shaver, transceiver, electronic notebook, calculator, memory card, portable tape recorder, radio, backup power supply, memory card, etc. It is done. Other consumer products include automobiles, electric vehicles, motors, lighting equipment, toys, game equipment, road conditioners, watches, strobes, cameras, medical equipment (such as pacemakers, hearing aids, and shoulder grinders). Furthermore, it can be used for various military purposes and space. Moreover, it can also combine with a solar cell.

In particular, it is preferably applied to applications that require high capacity and high rate discharge characteristics. For example, in power storage facilities and the like that are expected to increase in capacity in the future, high safety is essential, and further compatibility of battery performance is required. In addition, electric vehicles and the like are equipped with a high-capacity secondary battery and are expected to be charged every day at home, and further safety is required against overcharging. According to the present invention, it is possible to exhibit the excellent effect correspondingly to such a usage pattern.

An all-solid secondary battery is a secondary battery in which the positive electrode, the negative electrode, and the electrolyte are all solid. In other words, it is distinguished from an electrolyte type secondary battery using a carbonate-based solvent as an electrolyte. In this, this invention presupposes an inorganic all-solid-state secondary battery. The all-solid-state secondary battery includes an organic (polymer) all-solid-state secondary battery that uses a polymer compound such as polyethylene oxide as an electrolyte, and an inorganic all-solid-state secondary battery that uses the above-described Li—PS, LLT, LLZ, or the like. It is divided into batteries. The application of the polymer compound to the inorganic all-solid secondary battery is not hindered, and the polymer compound can be applied as a binder for the positive electrode active material, the negative electrode active material, and the inorganic solid electrolyte particles.
The inorganic solid electrolyte is distinguished from the above-described electrolyte (polymer electrolyte) using a polymer compound such as polyethylene oxide as an ion conductive medium, and the inorganic compound serves as an ion conductive medium. Specific examples include Li—PS, LLT, and LLZ. The inorganic solid electrolyte itself does not release cations (Li ions) but exhibits an ion transport function. On the other hand, a material that is added to the electrolytic solution or the solid electrolyte layer and serves as a source of ions that release cations (Li ions) is sometimes called an electrolyte, but it is distinguished from the electrolyte as the ion transport material. In this case, this is called “electrolyte salt” or “supporting electrolyte”. Examples of the electrolyte salt include LiTFSI (lithium bistrifluoromethanesulfonylimide).
In the present invention, the term “composition” means a mixture in which two or more components are uniformly mixed. However, as long as the uniformity is substantially maintained, aggregation or uneven distribution may partially occur within a range in which a desired effect is achieved. In particular, when it is referred to as a solid electrolyte composition, it basically refers to a composition (typically a paste) that is a material for forming a solid electrolyte layer or the like, and an electrolyte layer or the like formed by curing the composition. Shall not be included in this.

Hereinafter, the present invention will be described in more detail based on examples. The present invention is not construed as being limited thereby. In the following examples, “part” and “%” representing the composition are based on mass unless otherwise specified.

<Synthesis of sulfide-based inorganic solid electrolyte>
-Synthesis of Li-PS system glass-
As a sulfide-based inorganic solid electrolyte, T.I. Ohtomo, A .; Hayashi, M .; Tatsumisago, Y. et al. Tsuchida, S .; Hama, K .; Kawamoto, Journal of Power Sources, 233, (2013), pp231-235 and A.K. Hayashi, S .; Hama, H .; Morimoto, M .; Tatsumisago, T .; Minami, Chem. Lett. , (2001), pp 872-873, Li—PS glass was synthesized.

Specifically, in a glove box under an argon atmosphere (dew point −70 ° C.), 2.42 g of lithium sulfide (Li ₂ S, manufactured by Aldrich, purity> 99.98%) and diphosphorus pentasulfide (P ₂ S ₅ , 3.90 g manufactured by Aldrich, purity> 99%) was weighed, put into an agate mortar, and mixed for 5 minutes using an agate pestle. The mixing ratio of Li ₂ S and P ₂ S ₅ was set to Li ₂ S: P ₂ S ₅ = 75: 25 in terms of molar ratio.
A zirconia 45 mL container (manufactured by Fritsch) was charged with 66 zirconia beads having a diameter of 5 mm, and then the entire amount of the mixture of lithium sulfide and diphosphorus pentasulfide was charged, and the container was completely sealed under an argon atmosphere. . This container is set in a planetary ball mill P-7 (trade name, manufactured by Fritsch), mechanical milling is performed at a temperature of 25 ° C. and a rotation speed of 510 rpm for 20 hours, and a yellow powder of Li—PS system glass (sulfide inorganic) 6.20 g of solid electrolyte) was obtained.

<Preparation of current collector>
The surface of an aluminum foil (JIS H-4160, alloy number: 1N30-H, aluminum purity: 99.30%) having a thickness of 20 μm and a width of 200 mm is subjected to the following electrochemical roughening treatment (a1) and desmut treatment A current collector AL-1 was prepared for (b1).
(A1) Electrochemical roughening treatment (nitric acid electrolysis)
First, electrochemical roughening treatment was continuously performed using an AC voltage of 50 Hz. The electrolytic solution at this time was an aqueous solution of 8.9 g / L nitric acid (containing 4.4 g / L of aluminum ions) at a temperature of 50 ° C. The AC power supply waveform is subjected to electrochemical surface roughening using a carbon electrode as a counter electrode, using a trapezoidal rectangular wave alternating current with a time TP of 0.8 msec until the current value reaches a peak from zero, a duty ratio of 1: 1. It was. Ferrite was used for the auxiliary anode. The current density was 60A / dm ² at the peak current, and a 28.1A / dm ² in average, also the quantity of electricity in the aluminum foil of the electric quantity during anodic sum at 120c / dm ² there were. Then, water washing by spraying was performed.
Table 1 below shows the conditions for electrochemical surface roughening.
(B1) Desmutting treatment Next, a desmutting treatment by spraying was performed for 30 seconds with a 25% by weight aqueous solution of sulfuric acid having a temperature of 60 ° C. (containing 0.5% by weight of aluminum ions), followed by washing with water by spraying.

The current collector AL-1 was produced in the same manner as the current collector AL-1, except that the electrochemical roughening treatment conditions were changed to the treatment conditions shown in Table 1 below. Body AL-2 to 5 and current collector C-AL-1 to 3 for comparison were prepared.

For each of the current collectors AL-1 to 5 and C-AL-1 to 3 produced, the arithmetic average roughness Ra and the number of recesses having an average opening diameter of 0.3 to 3.0 μm were determined based on the above method. It was measured. The results are shown in Table 2 below.

Example 1
<Preparation of each composition>
-Preparation of solid electrolyte composition-
180 pieces of zirconia beads having a diameter of 5 mm are put into a 45 mL container (manufactured by Fritsch) made of zirconia, 9.5 g of the Li—PS system glass synthesized above, 0.5 g of PVdF—HFP, and 1,4 as a dispersion medium. -15.0 g of dioxane was charged. Thereafter, this container was set in a planetary ball mill P-7 (trade name, manufactured by Fritsch), and stirring was continued for 2 hours at a temperature of 25 ° C. and a rotation speed of 300 rpm to prepare a solid electrolyte composition.
The PVdF-HFP was measured by GPC under the following conditions, and the mass average molecular weight was 70,000.

-Preparation of composition for positive electrode-
180 zirconia beads having a diameter of 5 mm are put into a 45 mL container (manufactured by Fritsch) made of zirconia, 1.5 g of the Li—PS system glass synthesized above, 0.5 g of PVdF—HFP, and 1,4 as dispersion media. -Charge 12.3 g of dioxane. This container was set in a planetary ball mill P-7 (manufactured by Fritsch), and machine dispersion was continued for 2 hours under the conditions of a temperature of 25 ° C. and a rotation speed of 300 rpm. Thereafter, 8.0 g of lithium cobalt oxide (LCO, manufactured by Nippon Kagaku Kogyo Co., Ltd.) as an active material is put into the container, and the container is set again on the planetary ball mill P-7, at a temperature of 25 ° C. and a rotation speed of 100 rpm. Mixing continued for 15 minutes. In this way, a positive electrode composition was prepared.

-Preparation of composition for negative electrode-
180 pieces of zirconia beads having a diameter of 5 mm are put into a 45 mL container (manufactured by Fritsch) made of zirconia, and 8 parts by mass of graphite (spheroidized graphite powder manufactured by Nippon Graphite Industries, Ltd., described as “graphite” in Table 2 below) , 2 parts by mass of the Li—PS glass synthesized above, 0.3 part by mass of binder (HSBR, hydrogenated styrene butadiene rubber, JSR product name: Dynalon 1321P), and 10 parts by mass of heptane as a dispersion medium did. This container was set on a planetary ball mill P-7 (trade name, manufactured by Fritsch), and mechanical dispersion was continued for 90 minutes at a temperature of 25 ° C. and a rotation speed of 360 rpm to prepare a composition for a negative electrode.
The mass average molecular weight of the HSBR measured by GPC was 200,000, and Tg was −50 ° C.

-Measurement of mass average molecular weight-
As the mass average molecular weight of the binder used in the present invention, a standard polystyrene converted by GPC was adopted. The measurement apparatus and measurement conditions are shown below.
Column: TOSOH TSKgel Super HZM-H,
TOSOH TSKgel Super HZ4000,
TOSOH TSKgel Super HZ2000 (both trade names, manufactured by Tosoh Corporation)
A column connected with was used.
Carrier: Tetrahydrofuran Measurement temperature: 40 ° C
Carrier flow rate: 1.0 mL / min
Sample concentration: 0.1% by mass
Detector: RI (refractive index) detector

<Preparation of negative electrode sheet for all solid state secondary battery>
A negative electrode conductive film having a thickness of 4 μm was formed on a copper foil having a thickness of 20 μm as follows. That is, a commercially available conductive paint (trade name: Bunny Height # 27, manufactured by Nippon Graphite Industries Co., Ltd.) was diluted with a xylene / toluene = 1/1 mixed solvent and applied with a gravure coating machine so as to obtain a uniform film thickness. As a negative electrode conductive film, a carbon coated foil (volume resistivity: 0.4 Ω-cm) was obtained.

Next, the negative electrode composition prepared above was applied onto a conductive film provided on a copper foil by an applicator (trade name: SA-201 Baker type applicator, manufactured by Tester Sangyo Co., Ltd.) with adjustable clearance, and 80 After heating at 1 ° C. for 1 hour, the composition was further heated at 110 ° C. for 1 hour to dry the negative electrode composition. Then, using a heat press, the dried negative electrode composition is heated (110 ° C.) while being pressurized (605 MPa, 1 minute), and has a negative electrode active material layer with a thickness of 100 μm. A sheet was produced.

Furthermore, the solid electrolyte composition prepared above was applied onto the negative electrode active material layer by the above-described Baker type applicator, and the solid electrolyte composition was heated at 80 ° C. for 1 hour, and further heated at 110 ° C. for 6 hours. The sheet having the solid electrolyte layer formed on the negative electrode active material layer was pressurized (605 MPa, 1 minute) while being heated (120 ° C.) using a heat press, and the total film thickness with the negative electrode active material layer was 150 μm. A negative electrode sheet for an all-solid secondary battery with a solid electrolyte layer was produced. The film thickness of the solid electrolyte layer was 50 μm.

<Preparation of positive electrode sheet for all solid state secondary battery>
A positive electrode conductive film having a thickness of 4 μm was formed on the surface of the current collector AL-1 produced as described above as follows. That is, a commercially available conductive paint (trade name: Bunny Height # 27, manufactured by Nippon Graphite Industries Co., Ltd.) was diluted with a xylene / toluene = 1/1 mixed solvent and applied with a gravure coating machine so as to obtain a uniform film thickness. A carbon coated foil was obtained as a positive electrode conductive film.

Further, the positive electrode composition prepared above was applied onto the positive electrode conductive film by the above-mentioned Baker type applicator, heated at 80 ° C. for 1 hour, and further heated at 110 ° C. for 1 hour to dry the positive electrode composition. did. Then, using a heat press, the dried positive electrode composition is pressurized (605 MPa, 1 minute) while heating (120 ° C.), and has a positive electrode active material layer with a film thickness of 100 μm. A sheet was produced.

<Manufacture of all-solid-state secondary batteries>
An all-solid secondary battery shown in FIG. 2 was produced.
The negative electrode sheet for an all solid secondary battery with the solid electrolyte layer produced above was cut out into a disk shape with a diameter of 10 mm, and the positive electrode sheet for an all solid secondary battery was cut out into a disk shape with a diameter of 10 mm. The cut-out negative electrode sheet piece for an all-solid-state secondary battery with a solid electrolyte layer and the positive-electrode sheet piece for an all-solid-state secondary battery are attached by pressing at 605 MPa so that the solid electrolyte layer and the positive electrode active material layer face each other. After the alignment, all-solid-state secondary battery (coin battery) 13 was manufactured by placing it in a stainless steel 2032 type coin case 11 incorporating a spacer and washer (both not shown in FIG. 2) and applying a restraining pressure from the outside. . In FIG. 2, 12 shows the laminated body of the electrode sheet for all-solid-state secondary batteries which laminated | stacked the negative electrode sheet piece for all-solid-state secondary batteries with a solid electrolyte layer, and the positive electrode sheet piece for all-solid-state secondary batteries.
The layer configuration of the all-solid secondary battery manufactured in this way has the layer configuration shown in FIG.

(Examples 2 to 5 and Comparative Examples 1 to 3)
In the production of the all-solid secondary battery of Example 1, except that the current collector AL-1 was changed to the current collector shown in Table 2, the same as the production of the all-solid secondary battery of Example 1, The all solid state secondary batteries of Examples 2, 4, 5 and Comparative Examples 1 to 3 were produced, respectively.
Further, in the production of the all-solid-state secondary battery of Example 1, the current collector AL-1 was changed to the current collector shown in Table 2, and further replaced with a graphite positive electrode conductive film as follows. An all-solid secondary battery of Example 3 was produced in the same manner as in the production of the all-solid secondary battery of Example 1 except that a positive electrode conductive film (thickness 4 μm) of carbon nanotubes was formed.
(Method of forming carbon nanotube conductive film)
Add 5 parts by mass of carbon nanotubes (CNT) with a fiber diameter of 10 nm, 10 parts by mass of deoxycholic acid, 85 parts by mass of styrene butadiene rubber and 500 parts by mass of xylene / toluene = 1/1 mixed solvent, and prepare a dispersion using a bead mill. Then, coating was performed with a gravure coating machine so as to obtain a uniform film thickness to obtain a carbon-coated foil (volume resistivity: 4 × 10 ⁻⁴ Ω-cm).

<Presence or absence of voids in the solid electrolyte layer>
In each manufactured all-solid-state secondary battery, the presence or absence of fine voids in the solid electrolyte layer was confirmed as follows. The results are shown in Table 2.
The cross section of each all-solid-state secondary battery was observed with a scanning microscope (SEM: Hitachi High-Technologies Corporation, tabletop microscope TM-1000). The evaluation criteria for the presence or absence of voids are when an arbitrary cross section (63 μm × 48 μm) is observed at a magnification of 3000 times, and voids originating from the interface of the solid electrolyte particles (voids having a major axis length of 1 μm or more) cannot be confirmed. Was “no void”, and when the void was confirmed, it was designated “with void”.

<Peeling test of conductive film>
In each manufactured all-solid-state secondary battery, the presence or absence of peeling between the conductive film and the current collector was confirmed as follows. The results are shown in Table 2.
The all solid state secondary battery was disassembled, and the current collector was grasped with tweezers and peeled off. The ratio of the area where the conductive film was peeled off from the peeled current collector and was not transferred to the active material layer (remained as a conductive film) ((total area of conductive film not transferred / current collector surface area)) × 100 (%)) was calculated and judged in the following four stages A to D. The evaluation was performed on the positive electrode conductive film.
In this test, an evaluation “B” or higher is acceptable.
The calculated area ratio is
A: When it is 100% B: When it is 90% or more and less than 100% C: When it is 60% or more and less than 90% D: When it is less than 60%

<Short-circuit test>
In each manufactured all-solid-state secondary battery, the presence or absence of the occurrence of a short circuit was determined as follows based on the resistance value measured by the tester for the resistance of the positive electrode and the negative electrode of the all-solid-state secondary battery. When the measured resistance value is extremely low or approximately 0 V, it is assumed that the circuit is “short-circuited”. The results are shown in Table 2.

From the results shown in Table 2, the following was found. That is, the all-solid-state secondary batteries of Examples 1 to 5 in which the conductive film is formed on the surface of the current collector having a specific surface form in which the arithmetic average roughness Ra and the number of recesses are within a predetermined range are inorganic It was shown that fine voids could not be confirmed in the solid electrolyte layer, the adhesion between the current collector and the conductive film was high, and no short circuit occurred. On the other hand, in the all-solid-state secondary batteries of Comparative Examples 1 to 3 in which a conductive film is formed on the surface of the current collector that does not have the specific surface form, fine voids are confirmed in the inorganic solid electrolyte layer. Although it was not possible, it was shown that the conductive film peeled off from the current collector or a short circuit occurred.

(Examples 6 to 10)
In Examples 1 to 5, the same procedure as in Examples 1 to 5 except that the current collectors AL-1 to AL-5 used in each example were used instead of the copper foil as the negative electrode current collector. Each solid secondary battery was manufactured. About each manufactured all-solid-state secondary battery, the presence or absence of the space | gap of a solid electrolyte layer, a short circuit test, and the peeling test about a negative electrode electroconductive film were done like Example 1. FIG. As a result, Examples 6 to 10 obtained the same results as Examples 1 to 5, respectively.

While this invention has been described in conjunction with its embodiments, we do not intend to limit our invention in any detail of the description unless otherwise specified and are contrary to the spirit and scope of the invention as set forth in the appended claims. I think it should be interpreted widely.

This application claims the priority based on Japanese Patent Application No. 2015-242839 for which it applied for a patent in Japan on December 14, 2015, and these are all referred to here for description of this specification. As part of.

DESCRIPTION OF SYMBOLS 1 Negative electrode collector 2 Negative electrode active material layer 3 Solid electrolyte layer 4 Positive electrode active material layer 5 Positive electrode collector 6 Operating part 7 Negative electrode conductive film 8 Positive electrode conductive film 10 All-solid-state secondary battery 11 Coin case 12 All-solid-state two Laminate of electrode sheet for secondary battery 13 Coin battery

Claims

A positive electrode having a conductive film and a positive electrode active material layer in this order on the surface of the current collector, a negative electrode having a negative electrode active material layer, and an inorganic solid electrolyte layer between the positive electrode active material layer and the negative electrode active material layer; An all-solid secondary battery having
The all-solid-state secondary battery, wherein the surface has an arithmetic average roughness Ra of 0.24 to 0.38 μm and 10 to 80 concave portions with an average opening diameter of 0.3 to 3.0 μm / 100 μm 2 .
The negative electrode has a conductive film and the negative electrode active material layer in this order on the surface of the current collector,
2. The surface according to claim 1, wherein the surface has an arithmetic average roughness Ra of 0.24 to 0.38 μm, and 10 to 80 recesses / 100 μm 2 having an average opening diameter of 0.3 to 3.0 μm. All-solid secondary battery.
3. The all-solid-state secondary battery according to claim 1, wherein the surface has an arithmetic average roughness Ra of 0.25 to 0.31 and a number of recesses of 40 to 70/100 μm 2 .
The all-solid-state secondary battery according to any one of claims 1 to 3, wherein the conductive film is a film of a metal, a metal oxide, or a carbonaceous material.
On the surface of the current collector having a surface with an arithmetic average roughness Ra of 0.24 to 0.38 μm and 10 to 80/100 μm 2 concave portions with an average opening diameter of 0.3 to 3.0 μm An electrode sheet for an all-solid-state secondary battery having a conductive film and an active material layer in this order.
On the surface of the current collector having a surface with an arithmetic average roughness Ra of 0.24 to 0.38 μm and 10 to 80/100 μm 2 concave portions with an average opening diameter of 0.3 to 3.0 μm The manufacturing method of the electrode sheet for all-solid-state secondary batteries which forms a conductive film and then forms an active material layer.
The method for producing an electrode sheet for an all-solid-state secondary battery according to claim 6, wherein the surface is roughened by an electrochemical roughening treatment.
The method for producing an electrode sheet for an all-solid-state secondary battery according to claim 6 or 7, wherein the conductive film is formed by a vapor deposition method or a coating method using a metal, a metal oxide, or a carbonaceous material.
A method for producing an all-solid-state secondary battery, including the method for producing an electrode sheet for an all-solid-state secondary battery according to any one of claims 6 to 8.