WO2015147280A1 - All-solid-state secondary cell, method for manufacturing electrode sheet for cell, and method for manufacturing all-solid-state secondary cell - Google Patents

Abstract

　An all-solid-state secondary cell having a positive electrode active material layer, a negative electrode active material layer, and an inorganic solid-state electrolyte layer interposed between layers, wherein the inorganic solid electrolyte layer contains an ion-conductive inorganic solid electrolyte, and the interface between the positive electrode active material layer and the inorganic solid electrolyte layer and/or the interface between the negative electrode active material layer and the inorganic solid electrolyte layer has a maximum height roughness (Rz) of l.5-5 μm.

Description

All-solid secondary battery, method for producing battery electrode sheet, and method for producing all-solid secondary battery

The present invention relates to an all solid state secondary battery, a method for producing an electrode sheet for a battery, and a method for producing an all solid state secondary battery.

Currently, many lithium ion batteries that are widely used use an electrolytic solution. Attempts have been made to replace this electrolytic solution with a solid electrolyte and make all the constituent materials solid. Among them, the reliability and stability at the time of use are cited as advantages of the technology using an inorganic solid electrolyte. A flammable material such as a carbonate-based solvent is used as a medium for the electrolytic solution used in the lithium ion secondary battery. Although various measures have been taken, further measures in preparation for overcharge are desired. An all-solid-state secondary battery made of an inorganic compound that can make the electrolyte incombustible is positioned as a fundamental solution. In addition, it is an advantage that the inorganic solid electrolyte exhibits higher ionic conductivity than the polymer electrolyte.
A further advantage of the all-solid-state secondary battery is that it is suitable for increasing the energy density by stacking electrodes. Specifically, a battery having a structure in which an electrode and an electrolyte are directly arranged in series can be obtained. At this time, since the metal package for sealing the battery cell, the copper wire and the bus bar for connecting the battery cell can be omitted, the energy density of the battery is greatly increased. In addition, good compatibility with the positive electrode material capable of increasing the potential is also mentioned as an advantage.

Developed as a next-generation lithium ion secondary battery due to the above-described advantages, it has been vigorously developed (Non-patent Document 1). Among all-solid-state secondary batteries, the inorganic solid electrolyte layer is a member that is not found in liquid batteries or polymer batteries, and is expected to be developed. This solid electrolyte layer is usually formed by heating and pressing an electrolyte material applied thereto together with a binder or the like. Thereby, the joining state between the solid electrolyte layers can be changed from point contact to surface contact, the grain boundary resistance can be reduced, and the impedance can be lowered.

As for specific manufacturing procedures, the conventional all-solid-state secondary battery is mixed with powder or lump active material, conductive additive, binder, and other additives as necessary, and then pressed (pressure molding). (Patent Document 1). However, this method has very low productivity. Therefore, wet-on-dry processing procedures disclosed in Patent Documents 2 to 4 below have been proposed. The procedure is as follows. An organic solvent is further added to the powder mixture to prepare a slurry for the positive electrode active material layer or the negative electrode active material layer. These are each applied on a separate current collector and dried to form an electrode sheet. Next, a slurry for an inorganic solid electrolyte layer is applied on the dried / cured positive electrode active material layer or negative electrode active material layer, and dried to form an inorganic solid electrolyte layer.

JP 2008-123594 A JP 2007-227362 A International Publication No. 2011/105574 Pamphlet JP 2012-243476 A

According to the present inventors' confirmation, in the above wet-on-dry method, defects such as pinholes may occur in the active material layer and the inorganic solid electrolyte layer, which may cause a short circuit of the battery. I understand. In addition, each layer may be smoothed to hinder the improvement of ion conductivity, or interface peeling may occur due to a volume change during charging / discharging.

Accordingly, the present invention provides an all-solid-state secondary battery that exhibits good ion conductivity and effectively improves the peel resistance between the active material layer and the inorganic solid electrolyte layer through the development of a manufacturing technology for the all-solid-state secondary battery. It aims at providing the manufacturing method of a battery electrode sheet, and the manufacturing method of an all-solid-state secondary battery.

The inventors of the present invention have studied various manufacturing improvements regarding the manufacture of all-solid-state secondary batteries, and analyzed the effects through experimental confirmation. As a result, when the active material layer and the solid electrolyte layer are formed by a coating method, the following layer is applied while the previously formed layer is wet using a paste to improve performance quality. I found that I can do it. Specifically, moderate unevenness can be imparted to the interface of each layer after curing. Thereby, a physical anchor effect is expressed, it contributes to the fall of interface resistance, and ionic conductivity can be raised. Moreover, the improvement effect with respect to generation | occurrence | production of a pinhole is also expressed, and manufacturing quality can be improved. The present invention has been completed based on the above findings.

[1] An all-solid secondary battery having a positive electrode active material layer, a negative electrode active material layer, and an inorganic solid electrolyte layer interposed between the two layers,
The inorganic solid electrolyte layer includes an ion conductive inorganic solid electrolyte,
An all-solid secondary battery in which the maximum height roughness Rz of at least one of the interface between the positive electrode active material layer and the inorganic solid electrolyte layer or the interface between the negative electrode active material layer and the inorganic solid electrolyte layer is 1.5 μm to 5 μm.
The maximum height roughness means the maximum height roughness Rz of the roughness curve defined in JIS B0601-2013.
[2] In any of the positive electrode active material layer, the inorganic solid electrolyte layer, and the negative electrode active material layer, the number of pinholes is regulated to 16 or less per 1 mm ^2. Next battery.
[3] Slurry for forming the inorganic solid electrolyte layer while the positive electrode active material layer or the negative electrode active material layer is formed by applying a slurry and the positive electrode active material layer or the negative electrode active material layer is in a wet state. The all-solid-state secondary battery according to [1] or [2], wherein the inorganic solid electrolyte layer is formed by applying a coating.
[4] The all-solid-state secondary battery according to any one of [1] to [3], wherein the positive electrode active material layer and the negative electrode active material layer have a thickness of 1 μm to 1000 μm.
[5] The all-solid-state secondary battery according to any one of [1] to [4], wherein the inorganic solid electrolyte layer has a thickness of 1 μm or more and 1000 μm or less.
[6] Any of [1] to [5], wherein the maximum height roughness Rz of at least one of the interface between the positive electrode active material layer and the inorganic solid electrolyte layer or the negative electrode active material layer and the inorganic solid electrolyte layer is 3 μm or less. The all-solid-state secondary battery as described in any one.
[7] The all solid state secondary battery according to any one of [1] to [6], wherein the inorganic solid electrolyte is a sulfide-based inorganic solid electrolyte.
[8] The all-solid-state secondary battery according to any one of [1] to [6], wherein the inorganic solid electrolyte is an oxide-based inorganic solid electrolyte.
[9] The all-solid secondary battery according to [8], wherein the inorganic solid electrolyte is selected from compounds of the following formula.
· _Li x _La y TiO ₃
x = 0.3 to 0.7, y = 0.3 to 0.7
・ Li ₇ La ₃ Zr ₂ O ₁₂
・ Li _3.5 Zn _0.25 GeO ₄
LiTi ₂ P ₃ O ₁₂ ,
Li _{1 + x + y} (Al, Ga) _x (Ti, Ge) ₂ -xSi _y P ₃ -yO ₁₂
0 ≦ x ≦ 1, 0 ≦ y ≦ 1
・ Li ₃ PO ₄
・ LiPON
・ LiPOD
D is Ti, V, Cr, Mn, Fe, Co, Ni, Cu,
Zr, Nb, Mo, Ru, Ag, Ta, W, Pt, and Au
At least one selected from LiAON
A is at least one selected from Si, B, Ge, Al, C, Ga, etc. [10] At least one of the positive electrode active material layer, the negative electrode active material layer, and the inorganic solid electrolyte layer contains a binder. [1] The all-solid-state secondary battery according to any one of [9].
[11] A production method for forming an inorganic solid electrolyte layer on a positive electrode active material layer or a negative electrode active material layer by a coating method,
The step of applying a slurry for forming a positive electrode active material layer or a negative electrode active material layer on a current collector, while the obtained positive electrode active material layer or negative electrode active material layer is in a wet state, an inorganic solid electrolyte layer is formed. The manufacturing method of the electrode sheet for batteries which has the process of apply | coating the slurry for forming.
[12] The method for producing a battery electrode sheet according to [11], wherein the application of the slurry for the positive electrode active material layer or the negative electrode active material layer and the application of the slurry for the inorganic solid electrolyte layer are performed simultaneously or sequentially.
[13] A method for producing an all-solid secondary battery, wherein an all-solid secondary battery is produced via the method for producing an electrode sheet for a battery according to [11] or [12].

In this 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.

The all-solid-state secondary battery of the present invention exhibits good ionic conductivity and is excellent in peel resistance between the active material layer and the inorganic solid electrolyte layer. Moreover, according to the manufacturing method of the battery electrode sheet of this invention, and the manufacturing method of an all-solid-state secondary battery, the all-solid-state secondary battery which exhibits said outstanding performance can be manufactured suitably.
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.

FIG. 1 is a cross-sectional view schematically showing an all solid lithium ion secondary battery according to a preferred embodiment of the present invention. FIG. 2 is a process explanatory view schematically showing a manufacturing process according to a preferred embodiment of the present invention. FIG. 3 is a process explanatory view schematically showing a manufacturing process according to another preferred embodiment of the present invention. FIG. 4 is a cross-sectional view of a sample schematically shown for explaining a method for measuring each parameter in the roughness curve. FIG. 5 is a graph for explaining the definition of each parameter in the roughness curve. FIG. 6 is a photomicrograph (left) and an image processed image (right) showing an example of pinhole measurement.

The all-solid secondary battery of the present invention has specific irregularities at the interface between the inorganic solid electrolyte layer and the active material layer. Hereinafter, preferred embodiments thereof will be described. First, an example of an all-solid secondary battery which is a preferred application mode thereof will be described.

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 of the present embodiment includes a negative electrode current collector 1, a negative electrode active material layer 2, an inorganic solid electrolyte layer 3, a positive electrode active material layer 4, and a positive electrode current collector 5 in that order as viewed from the negative electrode side. Have in. Each layer is in contact with each other and has a laminated structure. 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 discharge, lithium ions (Li ⁺ ) accumulated in the negative electrode are returned to the positive electrode side, and electrons are supplied to the working part 6. In the example shown in the figure, a light bulb is adopted as the operation part 6 and is turned on by discharge. In the present invention, the solid electrolyte composition is preferably used as a constituent material of the negative electrode active material layer, the positive electrode active material layer, and the inorganic solid electrolyte layer. Among them, the inorganic solid electrolyte layer, the positive electrode active material layer, and the negative electrode active material layer It is preferable to use as all constituent materials. Note that the positive electrode active material layer and the negative electrode active material layer may be collectively referred to as an active material layer.

The thicknesses of the positive electrode active material layer 4 and the negative electrode active material layer 3 can be determined according to the target battery capacity. In consideration of general element dimensions, it is preferably 1 μm or more, more preferably 1.5 μm or more, further preferably 3 μm or more, and particularly preferably 5 μm or more. As an upper limit, it is preferable that it is 1000 micrometers or less, It is more preferable that it is 600 micrometers or less, It is further more preferable that it is 400 micrometers or less, It is especially preferable that it is 200 micrometers or less.
On the other hand, the inorganic solid electrolyte layer 3 is desirably as thin as possible while preventing a short circuit between the positive and negative electrodes. Furthermore, it is preferable that the effect of the present invention is remarkably exhibited. Specifically, it is preferably 1 μm or more, more preferably 1.5 μm or more, further preferably 3 μm or more, and more preferably 5 μm or more. It is particularly preferred that As an upper limit, it is preferable that it is 1000 micrometers or less, It is more preferable that it is 600 micrometers or less, It is further more preferable that it is 400 micrometers or less, It is especially preferable that it is 200 micrometers or less.
In FIG. 1, as described above, a laminate including a current collector, an active material layer, and a solid electrolyte layer is referred to as an “all-solid secondary battery”. The secondary battery electrode sheet may be housed in a casing (case) to be an all-solid secondary battery (for example, a coin battery, a laminate battery, or the like).

In the present invention, the maximum height roughness Rz of at least one of the interface between the positive electrode active material layer and the inorganic solid electrolyte layer or the negative electrode active material layer and the inorganic solid electrolyte layer is 1.5 μm to 5 μm. This means that the interface between the two layers has irregularities with moderate roughness. That is, by setting the range of the maximum height roughness Rz to be equal to or more than the above lower limit value, the layer interface has a three-dimensional roughness, so that the active material can be activated even if a volume change occurs due to charge / discharge. As a result, a so-called anchor effect that makes peeling at the interface between the active material and the inorganic solid electrolyte less likely occurs, and at the same time, the contact area between the active material and the inorganic solid electrolyte increases, resulting in improved ionic conductivity. From the viewpoint of the above action, the lower limit value of the maximum height roughness Rz is preferably 2 μm or more, and more preferably 2.3 μm or more. The upper limit is further preferably 4 μm or less, and particularly preferably 3 μm or less.
Unless otherwise specified in the present invention, the maximum height roughness Rz means Rz (maximum height roughness) in a roughness curve defined by JIS B0601-2013. In the definition of Rz in JIS B0601-2013, as shown in FIG. 5, it means the sum (Rz = Rp + Rv) of the maximum peak height Rp and the maximum valley depth Rv of the roughness curve at the reference length. The reference length in the present invention is 200 μm unless otherwise specified. The roughness curve of the layer interface and its Rz (maximum height roughness) can be measured by observing a cross section perpendicular to the layer with an SEM as shown in FIG.
In order to set the maximum height roughness Rz within a specific range, for example, a simultaneous multi-layer coating method or a wet-on-wet method described later can be employed. In this way, by applying the upper layer paste in a state in which the underlying layer is kept in a wet state, the underlying layer can flow appropriately and an interface with a suitable roughness can be realized. . However, in the present invention, the manufacturing method is not limited to these. For example, even if it is a powder laminated film or a dry cured film, after roughening the surface by pressing, it may be roughened by brushing or the like. Or it is good also as a setting which a predetermined unevenness | corrugation remains on the surface dried and pressed by applying an inorganic solid electrolyte particle or active material particle with a large particle size.
In order to adjust the maximum height roughness Rz, the size of the solid electrolyte particles and the active material particles to be contained in the solid electrolyte layer and the active material layer is changed in consideration of the flow of particles during the drying process. And adjusting the amount of the particles, adjusting the wettability and viscosity of the composition (paste) forming the solid electrolyte layer and the active material layer, and the like.

In the roughness curve of the layer interface, the density of the unevenness is not particularly limited, but it is preferably present relatively densely from the viewpoint of suitably exhibiting the effects of the present invention. In terms of the average length RSm of the roughness curve element, it is preferably 0.01 μm or more, more preferably 0.03 μm or more, and particularly preferably 0.05 μm or more. The upper limit is preferably 90 μm or less, more preferably 60 μm or less, and particularly preferably 50 μm or less.
The average length RSm of the roughness curve element can be measured by observing a cross section perpendicular to the layer with an SEM as shown in FIG. 4 unless otherwise specified. The reference length is set to 200 μm as in the measurement of the maximum roughness height.

In the present invention, in any of the positive electrode active material layer, the inorganic solid electrolyte layer, and the negative electrode active material layer, the number of pinholes is preferably regulated to 16 or less per 1 mm ² . This pinhole usually occurs when a base layer is dried and solidified and has irregularities, and a paste is applied thereon and dried. In particular, if there are convex portions (hole-like portions) in the underlying layer, the paste may not be placed there and may become pinholes.
In the present invention, this pinhole can be suppressed or prevented by employing a multilayer coating or a wet-on-wet method. The pinhole is preferably not present because it may cause an electrically non-uniform state at this portion, or may cause a peeling start point or a short circuit. From this viewpoint, in the present invention, the number of pinholes is preferably 8 or less per 1 mm ² , particularly preferably 4 or less, and particularly preferably 0.

<Coating method>
As described above, in the present invention, it is preferable to employ a multilayer coating method or a wet-on-wet method by using a paste as a raw material for forming each layer. Specifically, in this method, the positive electrode active material layer or the negative electrode active material layer is formed by applying a slurry, and the inorganic solid electrolyte layer is formed while the positive electrode active material layer or the negative electrode active material layer is in a wet state. Apply the slurry for. Here, the wet state can be defined as a state where the solid content concentration is 75% by mass or less. The solid content concentration is preferably 70% by mass or less, more preferably 60% by mass or less, and particularly preferably 50% by mass or less.
Although this specific method is not specifically limited, For example, the apparatus and process shown to FIG. 2 and FIG. 3 are mentioned.

The nozzle (simultaneous multi-layer device) 20 shown in FIG. 2 is provided with a hole for supplying the lower layer coating liquid 2A and a hole for supplying the upper layer coating liquid 2B. This hole extends in the depth direction of the paper surface and forms a semi-cylindrical space. This one end is in a released state, and the coating liquid is applied in the direction of the support 21. This released portion also extends in the depth direction of the paper surface and forms a space in the form on the slit.
The coating liquid supplied to each hole is supplied to the surface of the support (metal foil) 21 through the slit-shaped space. At this time, the lower layer coating solution 2 </ b> A slightly in front reaches the support 21 first to form the lower layer 22. The upper layer coating solution 2 </ b> B applied immediately thereafter is applied to the upper surface of the lower layer to form the upper layer 23. In this way, a three-layer structure in which the lower layer and the upper layer are provided on the support is realized.
Here, in the present invention, although not shown, it is preferable to apply a nozzle for applying three coating liquids. That is, in the example of FIG. 2, the nozzle has a structure in which another hole and a slit are further provided on the further side, whereby three layers of a lower layer, a middle layer, and an upper layer can be formed on the support. If necessary, a support (metal foil) can be disposed above the upper layer to obtain a structure of an all-solid-state secondary battery. In the present invention, an example can be given in which the lower layer is a positive electrode active material layer, the middle layer is an inorganic solid electrolyte layer, and the upper layer is a negative electrode active material layer. Thereby, the paste (coating liquid) of the upper negative electrode active material layer can be applied while maintaining the wettability of the positive electrode active material layer as the lower layer and the wettability of the inorganic solid electrolyte layer as the middle layer. As a result, the effect of suppressing pinholes as described above, and the effect of improving ion conductivity and binding properties can be expected.
Describing preferable process conditions in the present embodiment, the conveying speed of the support is preferably 2 to 500 m / min, more preferably 10 to 400 m / min, more preferably 30 to 360 m / min from the capability and accuracy of the conveying system of the coating machine. Is particularly preferred.
The supply speed of the coating liquid is set by the coating width, the coating speed, the target film thickness after drying and the solid content of the coating liquid, but is preferably 1 to 10000 ml / min from the ability of the liquid feed pump and the like, and preferably 2 to 8000 ml / min. Is more preferably 3 to 6000 ml / min, particularly preferably 4 to 4000 ml / min.
The liquid viscosity is preferably from 1 to 100,000 mPa · s, more preferably from 2 to 10,000 mPa · s, and even more preferably from 5 to 5000 mPa · s, from the viewpoint of the ability of the liquid feeding system, leveling properties after coating, and coating thickness after drying. 10 to 1000 mPa · s is particularly preferable.
Further, when the viscosity of the coating solution forming each layer is greatly different, the roughness of the interface becomes large. Therefore, the difference in the viscosity of the coating solution forming each layer is preferably 1000 mPa · s or less, more preferably 100 mPa · s or less, and 50 mPa · More preferably s or less, and particularly preferably 10 mPa · s or less.

FIG. 3 shows an example in which three different nozzles 30A, 30B, and 30C are used. In principle, the apparatus is the same as the apparatus of FIG. 2, but the lower layer coating liquid 3 </ b> A is applied on the support 31, and this forms the lower layer 32. Thereafter, in a state where the wettability of the lower layer is maintained, the intermediate layer coating solution 3B is applied at a slight interval, and this forms the intermediate layer 33. Thereafter, the upper layer coating liquid 3C is applied, and this forms the upper layer 34. In this manner, a laminated structure having a lower positive electrode active material layer, a middle inorganic solid electrolyte layer, and an upper negative electrode active material layer is realized. By arranging a support (electrode body) on the upper layer, an all-solid secondary battery structure can be obtained.
The preferable range of each process condition such as the conveyance speed of the support and the supply speed of each coating liquid is the same as the conditions in the apparatus of FIG.

In each of the above embodiments, when each coating liquid (paste) is sequentially applied, the application interval of each coating liquid is not particularly limited as long as the wettability of the previously applied layer is maintained, Within 2 seconds is preferable, within 0.5 seconds is more preferable, and within 0.2 seconds is particularly preferable.

Regarding the above-described simultaneous multi-layer coating or wet-on-wet manufacturing method or manufacturing apparatus, and preferred coating liquid properties, for example, JP-A-5-62167, JP-A-5-62177, JP-A-3181031, Reference can be made to JP-A-4-325919, JP-A-4-271016, JP-A-3-8471, JP-A-2-105331, and JP-A-2010-113819.

<Solid electrolyte composition>
(Inorganic solid electrolyte)
An inorganic solid electrolyte is an inorganic solid electrolyte. In the present specification, the term “solid electrolyte” means a solid electrolyte capable of moving ions therein. From this viewpoint, the inorganic solid electrolyte may be referred to as an ion conductive inorganic solid electrolyte in consideration of the distinction from the electrolyte salt (supporting electrolyte) described later. The ionic conductivity of the inorganic solid electrolyte is not particularly limited, but is preferably 1 × 10 ⁻⁶ S / cm or more, more preferably 1 × 10 ⁻⁵ S / cm or more in lithium ions. It is more preferably 10 ⁻⁴ S / cm or more, and particularly preferably 1 × 10 ⁻³ S / cm or more. There is no particular upper limit, but 1 S / cm or less is practical. Unless otherwise specified, the ion conductivity measurement method is based on the conditions measured in Examples described later.

Since inorganic solid electrolytes do not contain organic compounds such as polymer compounds and complex salts as electrolytes, they are clearly different from organic solid electrolytes (polymer electrolytes typified by PEO, organic electrolyte salts typified by LiTFSI, etc.). Differentiated. In addition, since the inorganic solid electrolyte is a non-dissociable solid in a steady state, it does not dissociate or release into cations and anions even in the liquid. In this respect, it is also clearly distinguished from inorganic electrolyte salts (LiPF ₆ , LiBF ₄ , LiFSI, LiCl, etc.) in which cations and anions are dissociated or liberated in the electrolytic solution or polymer. In general, the inorganic solid electrolyte has conductivity of metal ions (preferably lithium ions) belonging to Group 1 or Group 2 of the periodic table, but does not have electronic conductivity.

In the present invention, the electrolyte layer or the active material layer contains a metal ion (preferably lithium ion) conductive inorganic solid electrolyte belonging to Group 1 or Group 2 of the Periodic Table. As the inorganic solid electrolyte, a solid electrolyte material applied to this type of product 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.

(I) Sulfide-based inorganic solid electrolyte The sulfide-based inorganic solid electrolyte contains sulfur (S) and has ion conductivity of a metal belonging to Group 1 or Group 2 of the periodic table, and What has electronic insulation is preferable. For example, a lithium ion conductive inorganic solid electrolyte that satisfies the composition represented by the following formula (1) can be given.

Li _{a Mb} P _c S _d (1)

(In the formula, M represents an element selected from B, Zn, Si, Cu, Ga, and Ge. Ad represents the composition ratio of each element, and a: b: c: d represents 1 to 12, respectively. : 0 to 1: 1: 2 to 9 are satisfied.)

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

The sulfide-based inorganic solid electrolyte may be amorphous (glass) or crystallized (glass ceramic), or only part of it may be crystallized.

The ratio of Li ₂ S to P ₂ S ₅ in the Li—PS system glass and the 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 75:25. By setting the ratio of Li ₂ S to P ₂ S ₅ within this range, the lithium ion conductivity can be 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.

Specific examples of the compound include those using a raw material composition containing, for example, Li ₂ S and a sulfide of an element belonging to Group 13 to Group 15. Specifically, Li ₂ S—P ₂ S ₅ , 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 —Al ₂ S ₃ , Li ₂ S—SiS ₂ —P ₂ S ₅ , Li ₂ S—SiS ₂ —LiI, Li ₂ S—SiS ₂ —Li ₄ SiO ₄ , Li ₂ Examples thereof include S—SiS ₂ —Li ₃ PO ₄ and Li ₁₀ GeP ₂ S ₁₂ . Among them, Li ₂ S—P ₂ S ₅ , Li ₂ S—GeS ₂ —Ga ₂ S ₃ , Li ₂ SGeS ₂ —P ₂ S ₅ , Li ₂ S—SiS ₂ —P ₂ S ₅ , Li ₂ S— A crystalline and / or amorphous raw material composition made of SiS ₂ —Li ₄ SiO ₄ or Li ₂ S—SiS ₂ —Li ₃ PO ₄ is preferable because it has high lithium ion conductivity. Examples of a method for synthesizing a sulfide 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.

The sulfide-based inorganic solid electrolyte is, for example, T.M. 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, and the like.

(Ii) Oxide-based inorganic solid electrolyte The oxide-based solid electrolyte contains oxygen (O), has an ionic conductivity of a metal belonging to Group 1 or Group 2 of the periodic table, and is an electron What has insulation is preferable.

As specific compound examples, for example, Li _x La _y TiO ₃ [x = 0.3 to 0.7, y = 0.3 to 0.7] (LLT), Li ₇ La ₃ Zr ₂ O ₁₂ (LLZ) ), Li _3.5 Zn _0.25 GeO ₄ having a LISICON (Lithium super ionic conductor) type crystal structure, LiTi ₂ P ₃ O ₁₂ Al, Li ₁₊ having a NASICON (Natium super ionic conductor) type crystal structure, Li ₁₊ ) _X (Ti, Ge) ₂ -xSi _y P ₃ -yO ₁₂ (where 0 ≦ x ≦ 1, 0 ≦ y ≦ 1), the above Li ₇ La ₃ Zr ₂ O ₁₂ having a garnet-type crystal structure, etc. It is done. Phosphorus compounds containing Li, P and O are also desirable. For example, lithium phosphate (Li ₃ PO ₄ ), LiPON obtained by substituting part of oxygen of lithium phosphate with nitrogen, LiPOD (D is Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zr, Nb) , Mo, Ru, Ag, Ta, W, Pt, Au, etc.). LiAON (A is at least one selected from Si, B, Ge, Al, C, Ga, etc.) and the like can also be preferably used.
Among them, Li _{1 + x + y} (Al, Ga) _x (Ti, Ge) ₂ -xSi _y P ₃ -yO ₁₂ (where 0 ≦ x ≦ 1, 0 ≦ y ≦ 1) has high lithium ion conductivity. It is preferable because it is chemically stable and easy to handle. These may be used alone or in combination of two or more.

The ionic conductivity of the lithium ion conductive oxide-based inorganic solid electrolyte is preferably 1 × 10 ⁻⁶ S / cm or more, more preferably 1 × 10 ⁻⁵ S / cm or more. X 10 ⁻⁵ S / cm or more is particularly preferable.

In the present invention, it is particularly preferable to use an oxide-based inorganic solid electrolyte. Since the oxide-based inorganic solid electrolyte generally has a higher hardness, the interface resistance is likely to increase in the all-solid secondary battery. By applying the present invention, the effect becomes more prominent. In particular, the oxide-based inorganic solid electrolyte is hard and tends to be inferior in moldability, and the roughness of the interface between the active material layer and the inorganic solid electrolyte layer after coating tends to remain after molding. Therefore, it is effective to apply the present invention or a preferred embodiment thereof whose production is controlled at the application stage.
The said inorganic solid electrolyte may be used individually by 1 type, or may be used in combination of 2 or more type.

The average particle size of the inorganic solid electrolyte is not particularly limited, but is preferably selected in consideration of the influence on the interface roughness of the active material layer / inorganic solid electrolyte layer. Specifically, it is preferably 0.01 μm or more, more preferably 0.1 μm or more, further preferably 0.5 μm or more, and particularly preferably 1 μm or more. As an upper limit, it is preferable that it is 100 micrometers or less, It is more preferable that it is 50 micrometers or less, It is further more preferable that it is 10 micrometers or less, It is especially preferable that it is 5 micrometers or less. Unless otherwise specified, the average particle size of the inorganic solid electrolyte is determined according to the conditions measured in Examples described later.

The concentration of the inorganic solid electrolyte in the solid electrolyte composition is preferably 50% by mass or more and 100% by mass in 100% by mass of the solid component when considering both the battery performance and the reduction / maintenance effect of the interface resistance. % 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, when used together with a positive electrode active material or a negative electrode active material to be described later, the sum is preferably in the above concentration range.

(binder)
A binder can be used in the solid electrolyte composition of the present invention. Thereby, the above-described inorganic solid electrolyte particles can be bound to realize better ion conductivity. The type of the binder is not particularly limited, but a styrene-acrylic copolymer (see, for example, JP-A-2013-008611 and International Publication No. 2011-105574 pamphlet), and a hydrogenated butadiene copolymer (see, for example, JP-A-11-11). No. 086899, pamphlet of International Publication No. 2013/001623, etc.), polyolefin polymers such as polyethylene, polypropylene, polytetrafluoroethylene (for example, see JP 2012-99315 A), compounds having polyoxyethylene chains ( JP-A-2013-008611), norbornene-based polymer (JP-A-2011-233422) and the like can be used.

The polymer compound constituting the binder preferably has a weight average molecular weight of 5,000 or more, more preferably 10,000 or more, and particularly preferably 30,000 or more. As an upper limit, it is preferable that it is 1,000,000 or less, and it is more preferable that it is 400,000 or less. The molecular weight measurement method is based on the conditions measured in the examples described below unless otherwise specified.

The glass transition temperature (Tg) of the binder polymer is preferably 100 ° C. or less from the viewpoint of improving the binding property, more preferably 30 ° C. or less, and particularly preferably 0 ° C. or less. The lower limit is preferably −100 ° C. or higher, more preferably −80 ° C. or higher, from the viewpoint of manufacturing suitability and performance stability.
The binder polymer may be crystalline or amorphous. In the case of crystallinity, the melting point is preferably 200 ° C. or lower, more preferably 190 ° C. or lower, and particularly preferably 180 ° C. or lower. Although there is no lower limit in particular, 120 degreeC or more is preferable and 140 degreeC or more is more preferable.

In addition, the measurement from the created all-solid-state secondary battery is, for example, disassembling the battery, placing the electrode in water and dispersing the material, filtering, collecting the remaining solid, and measuring Tg described later The glass transition temperature can be measured by the method.

The average particle size of the binder polymer particles is preferably 0.01 μm or more, more preferably 0.05 μm or more, and particularly preferably 0.1 μm or more. As an upper limit, it is preferable that it is 500 micrometers or less, It is more preferable that it is 100 micrometers or less, It is especially preferable that it is 10 micrometers or less.
The standard deviation of the particle size distribution is preferably 0.05 or more, more preferably 0.1 or more, and particularly preferably 0.15 or more. The upper limit is preferably 1 or less, more preferably 0.8 or less, and particularly preferably 0.6 or less.
In the present invention, the average particle diameter and the degree of particle dispersion of the polymer particles are based on the conditions (dynamic light scattering method) employed in Examples described below unless otherwise specified.

In the present invention, the binder polymer particles preferably have a smaller particle size than the average particle size of the inorganic solid electrolyte particles. By setting the size of the polymer particles in the above range, it is possible to realize good adhesion and suppression of interfacial resistance in combination with the inorganic solid electrolyte particles having a predetermined particle size distribution. In addition, the measurement from the prepared all-solid-state secondary battery, for example, after disassembling the battery and peeling off the electrode, the electrode material is measured according to the method for measuring the particle size of the polymer described later, and measured in advance. This can be done by eliminating the measured value of the particle size of the particles other than the polymer.

The blending amount of the binder is preferably 0.1 parts by mass or more, and 0.3 parts by mass or more with respect to 100 parts by mass of the inorganic solid electrolyte (including this when an active material is used). More preferred is 1 part by mass or more. As an upper limit, it is preferable that it is 50 mass parts or less, It is more preferable that it is 20 mass parts or less, It is especially preferable that it is 10 mass parts or less.
For the solid electrolyte composition, in the solid content, the binder is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, and particularly preferably 1% by mass or more. preferable. As an upper limit, it is preferable that it is 50 mass% or less, it is more preferable that it is 20 mass% or less, and it is especially preferable that it is 10 mass% or less.
By using the binder in the above range, it is possible to more effectively achieve both the adhesion of the inorganic solid electrolyte and the suppression of the interface resistance.

¡Binders may be used alone or in combination of a plurality of types. Further, it may be used in combination with other particles.

The binder particles may be composed of only a specific polymer constituting the binder particles, or may be composed in a form containing another kind of material (polymer, low molecular compound, inorganic compound, etc.).

(Lithium salt [electrolyte salt])
In the all solid state secondary battery of the present invention, the solid electrolyte composition may contain a lithium salt. As the lithium salt, a lithium salt usually used in this type of product is preferable, and there is no particular limitation, but for example, the following are preferable.

(L-1) Inorganic lithium salts: inorganic fluoride salts such as LiPF ₆ , LiBF ₄ , LiAsF ₆ , LiSbF ₆ ; perhalogenates such as LiClO ₄ , LiBrO ₄ , LiIO ₄ ; inorganic chloride salts such as LiAlCl ₄ etc.

(L-2) Fluorine-containing organic lithium salt: perfluoroalkane sulfonate such as LiCF ₃ SO ₃ ; LiN (CF ₃ SO ₂ ) ₂ , LiN (CF ₃ CF ₂ SO ₂ ) ₂ , LiN (FSO ₂ ) ₂ , Perfluoroalkanesulfonylimide salts such as LiN (CF ₃ SO ₂ ) (C ₄ F ₉ SO ₂ ); perfluoroalkanesulfonylmethide salts such as LiC (CF ₃ SO ₂ ) ₃ ; Li [PF ₅ (CF ₂ CF ₂ CF ₃ )], Li [PF ₄ (CF ₂ CF ₂ CF ₃ ) ₂ ], Li [PF ₃ (CF ₂ CF ₂ CF ₃ ) ₃ ], Li [PF ₅ (CF ₂ CF ₂ CF ₂ CF _{3 )], Li [PF 4 (} CF 2 CF 2 CF 2 CF 3) 2], Li [PF 3 (CF 2 CF 2 CF 2 CF 3) 3] fluoroalkyl fluoride such as potash Acid salts, and the like.

(L-3) Oxalatoborate salt: lithium bis (oxalato) borate, lithium difluorooxalatoborate and the like.
Among these, LiPF ₆ , LiBF ₄ , LiAsF ₆ , LiSbF ₆ , LiClO ₄ , Li (Rf ¹ SO ₃ ), LiN (Rf ¹ SO ₂ ) ₂ , LiN (FSO ₂ ) ₂ , and LiN (Rf ¹ SO ₂ ) (Rf ² SO ₂ ), preferably LiPF ₆ , LiBF ₄ , LiN (Rf ¹ SO ₂ ) ₂ , LiN (FSO ₂ ) ₂ , and LiN (Rf ¹ SO ₂ ) (Rf ² SO ₂ ) More preferred are imide salts. Here, Rf ¹ and Rf ² each represent a perfluoroalkyl group.

The content of the lithium salt is preferably 0.1 parts by mass or more and more preferably 0.5 parts by mass or more with respect to 100 parts by mass of the inorganic solid electrolyte. As an upper limit, it is preferable that it is 10 mass parts or less, and it is more preferable that it is 5 mass parts or less.
In addition, the electrolyte used for electrolyte solution may be used individually by 1 type, or may combine 2 or more types arbitrarily.

(Dispersion medium)
In the solid electrolyte composition of the present invention, a dispersion medium in which the above components are dispersed may be used. When producing an all-solid secondary battery, it is preferable to add a dispersion medium to the solid electrolyte composition to make a paste from the viewpoint of uniformly coating the solid electrolyte composition to form a film. When forming the solid electrolyte layer of the all-solid secondary battery, the dispersion medium is removed by drying.
Examples of the dispersion medium include a water-soluble organic solvent. Specific examples include the following.
Alcohol compound solvent Methyl alcohol, ethyl alcohol, 1-propyl alcohol, 2-propyl alcohol, 2-butanol, ethylene glycol, propylene glycol, glycerin, 1,6-hexanediol, cyclohexanediol, sorbitol, xylitol, 2-methyl- 2,4-pentanediol, 1,3-butanediol, 1,4-butanediol, etc. ・ Ether compound solvents (including hydroxyl group-containing ether compounds)
Dimethyl ether, diethyl ether, diisopropyl ether, dibutyl ether, t-butyl methyl ether, cyclohexyl methyl ether, anisole, tetrahydrofuran, alkylene glycol alkyl ether (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.) Amide compound solvents N, N-dimethylformamide, 1-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, etc. ・ Ketone compound solvents Acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, etc. ・ Aromatic compound solvents benzene, toluene, etc. Aliphatic compound solvent Hexane, heptane, cyclohexane, methylcyclohexane, octane, pentane, cyclopentane, etc. ・ Nitrile compound solvent Acetonitrile, isobutyronitrile

In the present invention, it is particularly preferable to use an ether compound solvent, a ketone compound solvent, an aromatic compound solvent, or an aliphatic compound solvent. The dispersion medium preferably has a boiling point at normal pressure (1 atm) of 80 ° C. or higher, more preferably 90 ° C. or higher. The upper limit is preferably 220 ° C. or lower, and more preferably 180 ° C. or lower. The solubility of the binder in the dispersion medium is preferably 20% by mass or less, more preferably 10% by mass or less, and particularly preferably 3% by mass or less at 20 ° C. The lower limit is practically 0.01% by mass or more.
The said dispersion medium may be used individually by 1 type, or may be used in combination of 2 or more type.
In the wet-on-wet system (multilayer coating, etc.), it is preferable to select an appropriate one particularly at the boiling point of the solvent. This is because the evaporation rate is determined. For example, if a solvent having a low boiling point and excessively fast drying is used for the lower layer, liquid properties may be greatly different between the upper and lower layers when the upper layer is applied, and the interface may be disturbed. On the contrary, if the boiling point of the solvent is too high, the drying load increases, and the coating speed may be restricted.

In the present invention, it is preferable that the viscosity of the solid electrolyte composition is adjusted in relation to simultaneous multilayer coating or a wet-on-wet manufacturing method. The viscosity of the composition is preferably 1 mPa · s or more, more preferably 2 mPa · s or more, and particularly preferably 5 mPa · s or more. The upper limit is preferably 100,000 mPa · s or less, more preferably 10,000 mPa · s or less, and particularly preferably 5000 mPa · s or less.
Unless otherwise specified, the viscosity measurement method is based on the conditions measured in the examples described later.
In this invention, the quantity of the dispersion medium in a solid electrolyte composition can be made into arbitrary quantity with the balance of the viscosity of a solid electrolyte composition, and a dry load. Generally, it is preferably 20 to 99% by mass in the solid electrolyte composition.

(Method for preparing solid electrolyte composition)
The solid electrolyte composition of the present invention may be prepared by a conventional method, and examples thereof include a method of treating the inorganic solid electrolyte particles by a wet dispersion method or a dry dispersion method. Examples of the wet dispersion method include a ball mill, a bead mill, and a sand mill. Similarly, examples of the dry dispersion method include a ball mill, a bead mill, and a sand mill. After this dispersion, particles and aggregates other than the predetermined particle diameter can be removed by appropriately performing filtration.
In addition, in order to disperse the inorganic solid electrolyte particles in a wet or dry manner, various dispersion media such as various dispersion balls and dispersion beads can be used. Among them, zirconia beads, titania beads, alumina beads, and steel beads, which are high specific gravity dispersion media, are suitable.

(Positive electrode active material)
The solid electrolyte composition of the present invention may contain a positive electrode active material. Thereby, it can be set as the composition for positive electrode materials. It is preferable to use a transition metal oxide for the positive electrode active material, and it is preferable to have a transition element M ^a (one or more elements selected from Co, Ni, Fe, Mn, Cu, and V). Further, mixed element M ^b (elements of the first (Ia) group of the metal periodic table other than lithium, elements of the second (IIa) group, Al, Ga, In, Ge, Sn, Pb, Sb, Bi, Si , P, B, etc.) may be mixed. Examples of the transition metal oxide include specific transition metal oxides including those represented by any of the following formulas (MA) to (MC), or other transition metal oxides such as V ₂ O ₅ and MnO _2. Is mentioned. As the positive electrode active material, a particulate positive electrode active material may be used. Specifically, a transition metal oxide capable of reversibly inserting and releasing lithium ions can be used, but the specific transition metal oxide is preferably used.

The transition metal oxides, oxides containing the above transition element M ^a is preferably exemplified. At this time, a mixed element M ^b (preferably Al) or the like may be mixed. The mixing amount is preferably 0 to 30 mol% with respect to the amount of the transition metal. That the molar ratio of li / ^{M a} was synthesized were mixed so that 0.3 to 2.2, more preferably.

[Transition metal oxide represented by formula (MA) (layered rock salt structure)]
As the lithium-containing transition metal oxide, those represented by the following formula are preferable.
Li _a M ¹ O _b (MA)

Wherein, ^{M 1} is as defined above Ma. a represents 0 to 1.2 (preferably 0.2 to 1.2), and preferably 0.6 to 1.1. b represents 1 to 3 and is preferably 2. A part of M ¹ may be substituted with the mixed element M ^b . The transition metal oxide represented by the above formula (MA) typically has a layered rock salt structure.

The transition metal oxide is more preferably one represented by the following formulas.
_{(MA-1) Li g CoO} k
_{(MA-2) Li g NiO} k
_{(MA-3) Li g MnO} k
_{(MA-4) Li g Co} j Ni 1-j O k
_{(MA-5) Li g Ni} j Mn 1-j O k
_{(MA-6) Li g Co} j Ni i Al 1-j-i O k
_{(MA-7) Li g Co} j Ni i Mn 1-j-i O k

Here, g has the same meaning as a. j represents 0.1 to 0.9. i represents 0 to 1; However, 1-ji is 0 or more. k has the same meaning as b above. Specific examples of the transition metal compound include LiCoO ₂ (lithium cobaltate [LCO]), LiNi ₂ O ₂ (lithium nickelate) LiNi _0.85 Co _0.01 Al _0.05 O ₂ (nickel cobalt aluminum acid Lithium [NCA]), LiNi _0.33 Co _0.33 Mn _0.33 O ₂ (lithium nickel manganese cobaltate [NMC]), LiNi _0.5 Mn _0.5 O ₂ (lithium manganese nickelate).

The transition metal oxide represented by the formula (MA) partially overlaps, but when represented by changing the notation, those represented by the following are also preferable examples.
_{(I) Li g Ni x Mn} y Co z O 2 (x> 0.2, y> 0.2, z ≧ 0, x + y + z = 1)
Representative:
_{Li g Ni 1/3 Mn 1/3 Co 1/3} O 2
Li _g Ni _1/2 Mn _1/2 O _{2
(Ii) Li g Ni x Co} y Al z O 2 (x> 0.7, y>0.1,0.1> z ≧ 0.05, x + y + z = 1)
Representative:
_{Li g Ni 0.8 Co 0.15 Al 0.05} O 2

[Transition metal oxide represented by formula (MB) (spinel structure)]
Among the lithium-containing transition metal oxides, those represented by the following formula (MB) are also preferable.
Li _c M ² ₂ O _d (MB)

Wherein, ^{M 2} is as defined above Ma. c represents 0 to 2 (preferably 0.2 to 2), and preferably 0.6 to 1.5. d represents 3 to 5 and is preferably 4.

The transition metal oxide represented by the formula (MB) is more preferably one represented by the following formulas.
_{(MB-1) Li m Mn} 2 O n
_{(MB-2) Li m Mn} p Al 2-p O n
_{(MB-3) Li m Mn} p Ni 2-p O n

m is synonymous with c. n is synonymous with d. p represents 0-2. Specific examples of the transition metal compound are LiMn ₂ O ₄ and LiMn _1.5 Ni _0.5 O ₄ .

Preferred examples of the transition metal oxide represented by the formula (MB) include those represented by the following.
(A) LiCoMnO ₄
(B) Li ₂ FeMn ₃ O ₈
(C) Li ₂ CuMn ₃ O ₈
(D) Li ₂ CrMn ₃ O ₈
(E) Li ₂ NiMn ₃ O ₈
Of these, an electrode containing Ni is more preferable from the viewpoint of high capacity and high output.

[Transition metal oxide represented by formula (MC)]
As the lithium-containing transition metal oxide, it is also preferable to use a lithium-containing transition metal phosphor oxide, and among them, one represented by the following formula (MC) is also preferable.
Li _e M ³ (PO ₄ ) _f ... (MC)

In the formula, e represents 0 to 2 (preferably 0.2 to 2), and is preferably 0.5 to 1.5. f represents 1 to 5, and preferably 0.5 to 2.

The M ³ represents one or more elements selected from V, Ti, Cr, Mn, Fe, Co, Ni, and Cu. The ^{M 3} are, in addition to the mixing element ^{M b} above, Ti, Cr, Zn, Zr, may be substituted by other metals such as Nb. Specific examples include, for example, olivine-type iron phosphates such as LiFePO ₄ and Li ₃ Fe ₂ (PO ₄ ) ₃ , iron pyrophosphates such as LiFeP ₂ O ₇ , cobalt phosphates such as LiCoPO ₄ , and Li _3. Monoclinic Nasicon type vanadium phosphate salts such as V ₂ (PO ₄ ) ₃ (lithium vanadium phosphate) can be mentioned.
The a, c, g, m, and e values representing the composition of Li are values that change due to charge and discharge, and are typically evaluated as values in a stable state when Li is contained. In the above formulas (a) to (e), the composition of Li is shown as a specific value, but this also varies depending on the operation of the battery.

The average particle size of the positive electrode active material is preferably 0.01 μm or more, more preferably 0.1 μm or more, even more preferably 0.5 μm or more in consideration of the influence on the interface roughness of the active material layer / inorganic solid electrolyte layer. 1 μm or more is particularly preferable. As an upper limit, 100 micrometers or less are preferable, 50 or less are more preferable, 10 or less are more preferable, and 5 micrometers or less are especially preferable. 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 concentration of the positive electrode active material is not particularly limited, but is preferably 20 to 90% by mass, and more preferably 40 to 80% by mass in 100% by mass of the solid component in the solid electrolyte composition.
The positive electrode active materials may be used alone or in combination of two or more.

(Negative electrode active material)
The solid electrolyte composition of the present invention may contain a negative electrode active material. Thereby, it can be set as the composition for negative electrode materials. As the negative electrode active material, those capable of reversibly inserting and releasing lithium ions are preferable. 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 an alloy with lithium such as Sn or Si. Examples thereof include metals that can be formed. Of these, carbonaceous materials or lithium composite oxides are 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. Examples thereof include carbonaceous materials obtained by baking various synthetic resins such as artificial pitches such as petroleum pitch, natural graphite, and vapor-grown graphite, and PAN-based resins and furfuryl alcohol resins. Furthermore, various carbon fibers such as PAN-based carbon fiber, cellulose-based carbon fiber, pitch-based carbon fiber, vapor-grown carbon fiber, dehydrated PVA-based carbon fiber, lignin carbon fiber, glassy carbon fiber, activated carbon fiber, mesophase micro Examples thereof include spheres, graphite whiskers, and flat graphite.

These carbonaceous materials can be divided into non-graphitizable carbon materials and graphite-based carbon materials depending on the degree of graphitization. Further, the carbonaceous material preferably has a face spacing, 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 group of compounds consisting of the above amorphous oxide and chalcogenide, amorphous metal oxides and chalcogenides are more preferable, and elements in groups 13 (IIIB) to 15 (VB) of the periodic table are preferable. Particularly preferred are oxides and chalcogenides composed of one kind of Al, Ga, Si, Sn, Ge, Pb, Sb, Bi or a combination of two or more kinds thereof. 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 ₅ , Bi ₂ O ₃ , Bi ₂ O ₄ , SnSiO ₃ , GeS, SnS, SnS ₂ , PbS, PbS ₂ , Sb ₂ S ₃ , Sb ₂ S ₅ , such as SnSiS ₃ may preferably be mentioned. Moreover, these may be a complex oxide with lithium oxide, for example, Li ₂ SnO ₂ .

The average particle size of the negative electrode active material is preferably 0.01 μm or more, more preferably 0.1 μm or more, even more preferably 0.5 μm or more in consideration of the influence on the interface roughness of the active material layer / inorganic solid electrolyte layer. 1 μm or more is particularly preferable. As an upper limit, 100 micrometers or less are preferable, 50 or less are more preferable, 10 or less are more preferable, and 5 micrometers or less are especially preferable. To obtain a predetermined particle size, a well-known 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 size, 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 chemical formula of the compound obtained by the above firing method can be calculated from an inductively coupled plasma (ICP) emission spectroscopic analysis method as a measurement method, and from a mass difference between powders before and after firing as a simple method.

Examples of the negative electrode active material that can be used in combination with the amorphous oxide negative electrode active material centering on Sn, Si, and Ge include carbon materials that can occlude and release lithium ions or lithium metal, lithium, lithium alloys, lithium A metal that can be alloyed with is preferable.

In the all solid state secondary battery of the present invention, it is also preferable to apply a negative electrode active material containing Si element. In general, a Si negative electrode can occlude more Li ions than current carbon negative electrodes (graphite, acetylene black, etc.). That is, since the amount of Li ion storage per weight increases, the battery capacity can be increased. As a result, there is an advantage that the battery driving time can be extended, and use in a battery for vehicles is expected in the future. On the other hand, it is known that the volume change associated with insertion and extraction of Li ions is large. In one example, the volume expansion of the carbon negative electrode is about 1.2 to 1.5 times, and the volume of Si negative electrode is about three times. There is also an example. By repeating this expansion and contraction (repeating charge and discharge), the durability of the electrode layer is insufficient, and for example, contact shortage is likely to occur, and cycle life (battery life) is shortened.
According to the solid electrolyte composition of the present invention, even in an electrode layer in which such expansion / contraction increases, the high durability (strength) can be exhibited and the excellent advantages can be exhibited more effectively. .

The concentration of the negative electrode active material is not particularly limited, but is preferably 10 to 80% by mass, more preferably 20 to 70% by mass in 100% by mass of the solid component in the solid electrolyte composition.

In the above embodiment, an example in which the solid electrolyte composition according to the present invention contains a positive electrode active material or a negative electrode active material has been described, but the present invention is not construed as being limited thereto. For example, a paste containing a positive electrode active material or a negative electrode active material may be prepared as a composition that does not contain inorganic solid electrolyte particles. Moreover, you may make the active material layer of a positive electrode and a negative electrode contain a conductive support agent suitably as needed. As general electron conductive materials, carbon fibers such as graphite, carbon black, acetylene black, ketjen black, carbon nanotubes, metal powders, metal fibers, polyphenylene derivatives, and the like can be included.
The said negative electrode active material may be used individually by 1 type, or may be used in combination of 2 or more type.

<Current collector (metal foil)>
As the positive / negative current collector, an electron conductor that does not cause a chemical change is preferably used. As the current collector of the positive electrode, in addition to aluminum, stainless steel, nickel, titanium, etc., the surface of aluminum or stainless steel is preferably treated with carbon, nickel, titanium, or silver. Among them, aluminum and aluminum alloys are preferable. More preferred. As the negative electrode current collector, aluminum, copper, stainless steel, nickel, and titanium are preferable, and aluminum, copper, and a copper alloy are more preferable.

As the shape of the current collector, a film sheet is usually used, but a net, a punched one, a lath body, a porous body, a foamed body, a molded body of a fiber group, and the like can also be used. The thickness of the current collector is not particularly limited, but is preferably 1 μm to 500 μm. Moreover, it is also preferable that the current collector surface is roughened by surface treatment.

<Preparation of all-solid secondary battery>
The all-solid-state secondary battery may be manufactured by a conventional method. The coating method for each of the above compositions is preferably the simultaneous multi-layer coating method or the wet-on-wet method described above. At this time, a heat treatment is performed after each application of the composition forming the positive electrode active material layer (paste), the composition forming the inorganic solid electrolyte layer (paste), and the composition forming the negative electrode active material layer (paste). It is preferable. Although heating temperature is not specifically limited, 30 degreeC or more is preferable and 60 degreeC or more is more preferable. The upper limit is preferably 300 ° C. or lower, and more preferably 250 ° C. or lower.

<Use of all-solid-state secondary battery>
The all solid state secondary battery according to the present invention can be applied to various uses. Although the application mode is not particularly limited, 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 cellular phone, a cordless phone, a pager, a handy terminal, a portable fax machine, a portable copy, Examples include portable printers, headphone stereos, video movies, LCD TVs, handy cleaners, portable CDs, minidiscs, electric shavers, transceivers, electronic notebooks, calculators, memory cards, portable tape recorders, radios, backup power supplies, and memory cards. 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 use and space use. 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 reliability is indispensable and further compatibility of battery performance is required. In addition, electric vehicles and the like are equipped with high-capacity secondary batteries and are expected to be charged every day at home, and thus more reliability is required for 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 refers to 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 is classified into a 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 Li-PS, LLT, or LLZ. Is done. 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 an electrolyte (polymer electrolyte) using the above-described polymer compound 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. This is sometimes referred to as “electrolyte salt” or “supporting electrolyte”. Examples of the electrolyte salt include LiTFSI (lithium bistrifluoromethanesulfonimide).
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, the solid electrolyte composition basically refers to a composition (typically a paste) that is a material for forming the electrolyte layer, and the electrolyte layer formed by curing the composition includes It shall not be included.

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

Synthesis of sulfide-based inorganic solid electrolyte (Li—PS glass) Lithium sulfide (Li ₂ S, manufactured by Aldrich, purity> 99.98%) in a glove box under an argon atmosphere (dew point of −70 ° C.) 2.42 g and diphosphorus pentasulfide (P ₂ S ₅ , Aldrich, purity> 99%) 3.90 g were weighed, put into an agate mortar, and mixed for 5 minutes using an agate pestle. Incidentally, Li ₂ S and _P 2 _{S 5} at a molar ratio of _{Li 2 S: P 2 S 5} = 75: was 25.
66 zirconia beads having a diameter of 5 mm were introduced into a 45 mL container (manufactured by Fritsch) made of zirconia, the whole mixture of lithium sulfide and diphosphorus pentasulfide was introduced, and the container was completely sealed under an argon atmosphere. A container is set on a planetary ball mill P-7 manufactured by Frichtu, and mechanical milling is performed at a temperature of 25 ° C. and a rotation speed of 510 rpm for 20 hours to obtain 6.20 g of a yellow powder sulfide solid electrolyte material (Li / P / S glass). Obtained.

Preparation Example of Solid Electrolyte Composition (i) Preparation of Solid Electrolyte Composition S-1 160 zirconia beads having a diameter of 5 mm were placed in a 45 mL zirconia container (manufactured by Fritsch), and an inorganic solid electrolyte LLT (manufactured by Toyoshima Seisakusho) After adding 9.0 g of HSBR (JSR Dynalon 1321P) as a binder and 15.0 g of toluene as a dispersion medium, the container was set in a planetary ball mill P-7 manufactured by Fritsch Co., and rotated at 360 rpm. The wet dispersion was performed to obtain a solid electrolyte composition S-1. The average particle size of the inorganic solid electrolyte particles was as shown in the table. The viscosity was 540 mPa · s (25 ° C.).
The HSBR had a weight molecular weight of 200,000 and a Tg of −50 ° C.

Solid electrolyte composition S-2 was prepared in the same manner as solid electrolyte composition S-1.
In Table 1 below, the solid electrolyte compositions S-1 and S-2 used for the solid electrolyte layer are indicated as LLT (S-1) and LLT (S-2), respectively.

(Ii) Preparation of Solid Electrolyte Composition S-3 160 zirconia beads having a diameter of 5 mm are placed in a 45 mL container (manufactured by Fritsch) made of zirconia, and a sulfide inorganic solid electrolyte (Li—PS glass) 9. 0g, HSBR (JSR Dynalon 1321P) 0.3g as binder and 15.0g toluene as dispersion medium were added, and then the vessel was set on a planetary ball mill P-7 manufactured by Fritsch, and wetted at 360 rpm for 90 minutes. Dispersion was performed to obtain a solid electrolyte composition S-3. The average particle diameter of the sulfide solid electrolyte particles was as shown in the table. The viscosity was 600 mPa · s (25 ° C.).
In Table 1 below, the solid electrolyte composition S-3 used for the solid electrolyte layer was described as sulfide (S-3).

Preparation of secondary battery positive electrode composition In a planetary mixer (TK Hibismix, manufactured by PRIMIX), 100 parts of lithium cobaltate, 5 parts of acetylene black, 75 parts of the solid electrolyte composition S-1 obtained above, N -270 parts of methylpyrrolidone were added and stirred at 40 rpm for 1 hour. The viscosity was 120 mPa · s (25 ° C.).

Preparation of composition for secondary battery negative electrode Planetary mixer (TK Hibismix, manufactured by PRIMIX), 100 parts of graphite (Nippon Graphite Industries spheroidized graphite powder), 5 parts of acetylene black, solid electrolyte obtained above Composition S-1 (75 parts) and N-methylpyrrolidone (270 parts) were added, and the mixture was stirred at 40 rpm for 1 hour. The viscosity was 110 mPa · s (25 ° C.).

(Comparative example) Wet-on-dry method (c02)
Preparation of positive electrode for secondary battery The composition for positive electrode of the secondary battery obtained above was applied with a stainless steel (SUS316L) foil having a thickness of 20 μm and an applicator having an arbitrary clearance, and heated at 80 ° C. for 1 hour and further at 110 ° C. for 1 hour. Then, the coating solvent was dried. When this dried product was sampled and the solid content concentration was identified, it was 99% by mass or more (the wet state was lost). Then, it heated and pressurized so that it might become arbitrary density using the heat press machine, and the positive electrode for secondary batteries was obtained.

Production of Secondary Battery Electrode Sheet On the positive electrode for secondary battery obtained above, the solid electrolyte composition obtained above was applied with an applicator having an arbitrary clearance, and 80 ° C. for 1 hour and further 110 ° C. Heated for 1 hour. Thereafter, the composition for a secondary battery negative electrode obtained above was further applied and heated at 80 ° C. for 1 hour and further at 110 ° C. for 1 hour. A stainless steel (SUS316L) foil having a thickness of 20 μm was combined on the negative electrode layer, and heated and pressurized to an arbitrary density using a heat press machine to obtain an electrode sheet for a secondary battery.

(Comparative example) Powder lamination method (c01)
Preparation Example of Solid Electrolyte Composition 160 zirconia beads having a diameter of 5 mm are put into a 45 mL container (manufactured by Fritsch) made of zirconia, 9.0 g of inorganic solid electrolyte LLT (manufactured by Toyoshima Seisakusho), and HSBR (manufactured by JSR) as a binder. After adding 0.3 g of Dynalon 1321P), the container was set on a planetary ball mill P-7 manufactured by Fritsch, and dry dispersion was performed at a rotation speed of 360 rpm for 120 minutes to obtain a solid electrolyte composition S-2. The average particle size of the inorganic solid electrolyte particles was as shown in the table.
Preparation Example of Secondary Battery Positive Electrode Composition A planetary mixer (TK Hibismix, manufactured by PRIMIX) was charged with 100 parts of lithium cobaltate, 5 parts of acetylene black, and 75 parts of the solid electrolyte composition S-2 obtained above. In addition, stirring was performed at 40 rpm for 1 hour.
Preparation Example of Secondary Battery Negative Electrode Composition Planetary mixer (TK Hibismix, manufactured by PRIMIX), 100 parts of graphite (Nippon Graphite Industries spheroidized graphite powder), 5 parts of acetylene black, solid obtained above 75 parts of the electrolyte composition S-2 was added and stirred at 40 rpm for 1 hour.
Preparation of Secondary Battery Electrode Sheet The secondary battery positive electrode composition powder obtained above was placed on a 20 μm thick SUS316L foil as a positive electrode current collector so as to have an arbitrary thickness. Then, the positive electrode composition powder for the secondary battery together with the positive electrode current collector is heated and pressurized to a desired density using a heat press machine to form a positive electrode composition powder molding layer on the surface of the positive electrode current collector did.
Next, the solid electrolyte composition powder obtained above was placed on the positive electrode composition powder molding layer so as to have an arbitrary thickness. Then, the positive electrode current collector and the positive electrode composition powder molding layer together with the solid electrolyte composition powder are heated and pressurized to a desired density using a heat press machine, and the solid electrolyte is applied to the surface of the positive electrode composition powder molding layer. A composition powder molding layer was formed.
Further, the negative electrode composition powder was placed on the solid electrolyte composition powder molding layer so as to have an arbitrary thickness. A SUS316L foil having a thickness of 20 μm as a negative electrode current collector was laminated on the surface.
And it heated and pressurized so that it might become arbitrary density using a heat press machine, and the electrode sheet for secondary batteries was obtained.

(Example) Simultaneous multilayer coating method (101 to 103, 105)
An all-solid secondary battery was manufactured using the apparatus shown in FIG. However, although the apparatus shown in FIG. 2 supplies two liquids, in this embodiment, an apparatus (nozzle) that supplies three liquids is used. Specifically, a stainless steel (SUS316L) foil having a thickness of 20 μm was supplied as the support 21. On top of this, the positive electrode composition, the solid electrolyte composition S-1 and the negative electrode composition prepared above were simultaneously applied as shown in the figure. At this time, the positive electrode composition is supplied as the lower layer coating liquid 2A, the solid electrolyte composition S-1 is supplied as the upper layer coating liquid 2B, and the negative electrode composition as the upper layer coating liquid (not shown). Supplied. The temperature of the nozzle of the supply unit was room temperature (about 25 ° C.).
The positive electrode composition and the negative electrode composition when the solid electrolyte composition was laminated were sampled, and the solid content concentration was measured. As a result, in all cases, the solid content was about 40% by mass (the wet state was maintained). Then, it heated at 80 degreeC for 1 hour and further 110 degreeC for 1 hour, laminated | stacked SUS316L foil, and heated and pressurized so that it might become arbitrary density using the heat press machine, and obtained the electrode sheet for secondary batteries.
In addition, the thickness of the cured film (inorganic solid electrolyte layer) of a solid electrolyte composition made a difference by adjusting the supply amount of the raw material composition.

(Example) Wet-on-wet system (104)
An all-solid secondary battery was manufactured using the apparatus shown in FIG. Specifically, a stainless steel (SUS316L) foil having a thickness of 20 μm was supplied as the support 31. On top of this, the positive electrode composition, the solid electrolyte composition (S-1) and the negative electrode composition prepared above were simultaneously applied as shown in the figure. At this time, the positive electrode composition was supplied as the previous coating liquid 3A, the solid electrolyte composition (S-1) was supplied as the subsequent coating liquid 3B, and the negative electrode composition was further supplied as the subsequent coating liquid 3C. . The temperature of the nozzle of the supply unit was room temperature (about 25 ° C.). Then, it heated at 80 degreeC for 1 hour and further 110 degreeC for 1 hour, laminated | stacked SUS316L foil, and heated and pressurized so that it might become arbitrary density using the heat press machine, and obtained the electrode sheet for secondary batteries.

<Table notes>
SUS316L: Ni / Cr / Mo / Fe = 12/17 / 2.5 / 68.5 (mass ratio)
LLT: Li _0.33 La _0.55 TiO ₃
LLZ: Li ₇ La ₃ Zr ₂ O ₁₂
Sulfide: Sulfide inorganic solid electrolyte (Li-PS glass)
Simultaneous layering: Simultaneous layering method wet on wet: Wet on wet method wet on dry: Wet on dry method Powder stacking: Powder stacking method Particle size: Average particle size Average length: Average length of roughness curve element

The measurement method of each parameter is as follows.
<Surface roughness measurement method>
The cross section of the laminate composed of the positive electrode layer / inorganic solid electrolyte layer / negative electrode layer is photographed at 1000 times using SEM. The cross section was cut with a diamond knife manufactured by DiATOME, and a portion suitable for observation was selected. The average value was employ | adopted as a measurement location as 20 locations. The curve of the interface of the positive electrode layer or negative electrode layer and inorganic solid electrolyte layer of the obtained image is obtained (in FIG. 4, the curve obtained in the example of the positive electrode layer is illustrated by a line). For the obtained roughness curve, the sum of the maximum peak height Rp and the maximum valley depth Rv of the roughness curve at the reference length of 200 μm (Rz = Rp + Rv) according to the definition of the maximum height roughness Rz of JIS B0601-2013 (FIG. 5). )
Similarly, RSm was measured according to JIS B0601-2013, and 50 line segments within a 200 μm length were arbitrarily selected. The average value was adopted as the evaluation result.

<Pinhole measurement method>
For example, after applying and drying the positive electrode layer forming slurry on the current collector and then applying and drying the inorganic solid electrolyte layer forming slurry, the surface of the dried inorganic solid electrolyte layer is 200 times using SEM (Hitachi). Take a picture with High Technologies TM-1000). The target area to be measured is 900 μm × 700 μm.
The following A to C were evaluated by counting the number of pinholes in 50 arbitrarily selected regions and averaging them per 1 mm ² .
A: A pinhole was not confirmed.
B: 16 or less were confirmed.
C: 17 or more were confirmed.

<Measuring method of particle size and particle size distribution>
Using a dynamic light scattering particle size distribution analyzer (LB-500 manufactured by Horiba, Ltd.) in accordance with JIS 8826: 2005, the inorganic solid electrolyte particle dispersion is dispensed into a 20 ml sample bottle, and the solid content concentration with toluene Was adjusted to 0.2 mass%, data was acquired 50 times using a 2 ml measuring quartz cell at a temperature of 25 ° C., and the obtained volume-based arithmetic average was taken as the average particle diameter.

<Evaluation of electrode binding>
In the secondary battery electrode sheet preparation step, the binding property was evaluated using the electrode sheet before applying the negative electrode current collector SUS316L foil (the state in which the negative electrode composition was applied and dried). . An adhesive tape (cellophane tape (“CT24”, manufactured by Nichiban Co., Ltd.)) was applied to the negative electrode composition after drying, and the peeled area was visually confirmed when peeled off at a constant speed. The area ratio of the part that was not peeled was evaluated as follows.
A: 100%
B: 95% or more and less than 100% C: Less than 95%

<Measurement of ionic conductivity>
The electrode sheet for the secondary battery obtained above was punched into a disk shape having a diameter of 14.5 mm, and was put into a stainless steel 2032 type coin case incorporating a spacer and a washer to produce a coin battery. From the outside of the coin battery, it was sandwiched between jigs capable of applying a pressure of 500 kgf / cm ² between the electrodes, and obtained by an AC impedance method in a constant temperature bath at 30 ° C. The results are shown in Table 1 according to the following evaluation criteria.
A: Based on the comparative example c01, which exceeds + 10% B: Above the conductivity, based on the comparative example c01, + 10% or less C: Based on the comparative example c01, below this conductivity

<Measurement of molecular weight>
The weight average molecular weight in terms of standard polystyrene was measured by gel permeation chromatography (GPC). As a measuring method, it measured by the method of the following conditions.
(conditions)
Column: TOSOH TSKgel Super HZM-H, TOSOH TSKgel Super HZ4000, TOSOH TSKgel Super HZ2000 connected to column Carrier: Tetrahydrofuran

<Measurement method of viscosity>
50 mL of the solid electrolyte composition was measured with a B-type viscometer BL2 manufactured by Tokyo Keiki Co., Ltd. The sample was kept warm at the measurement start temperature until the temperature became constant, and the measurement was started thereafter. The measurement temperature was 25 ° C.

<Measurement method of solid content concentration of paste>
The solid content was calculated from the weight of the paste before and after heating and drying using the reduced amount as a solvent using an infrared heating and drying mass measuring machine MOC-102H manufactured by Shimadzu Corporation.

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 priority based on Japanese Patent Application No. 2014-070093 filed in Japan on March 28, 2014 and Japanese Patent Application No. 2015-030377 filed on February 19, 2015 in Japan. Which are hereby incorporated by reference herein as part of their description.

DESCRIPTION OF SYMBOLS 1 Negative electrode current collector 2 Negative electrode active material layer 3 Inorganic solid electrolyte layer 4 Positive electrode active material layer 5 Positive electrode current collector 6 Working part 10 All-solid secondary battery 20 Nozzle 2A Lower layer coating liquid 2B Upper layer coating liquid 21 Support ( Metal foil)
22 Coating film lower layer 23 Coating film upper layer 30A, 30B, 30C Nozzle 3A Lower layer coating liquid 3B Middle layer coating liquid 3C Upper layer coating liquid 31 Support (metal foil)
32 Coating film lower layer 33 Coating film middle layer 34 Coating film upper layer

Claims (13)

1. An all-solid-state secondary battery having a positive electrode active material layer, a negative electrode active material layer, and an inorganic solid electrolyte layer interposed between the two layers,
   The inorganic solid electrolyte layer includes an ion conductive inorganic solid electrolyte,
   An all-solid secondary battery in which the maximum height roughness Rz of at least one of the interface between the positive electrode active material layer and the inorganic solid electrolyte layer or the interface between the negative electrode active material layer and the inorganic solid electrolyte layer is 1.5 μm to 5 μm.
   The maximum height roughness means the maximum height roughness Rz of the roughness curve defined in JIS B0601-2013.
2. ^2. The all-solid-state secondary battery according to claim 1, wherein the number of pinholes in each of the positive electrode active material layer, the inorganic solid electrolyte layer, and the negative electrode active material layer is regulated to 16 or less per 1 mm ² .
3. While the positive electrode active material layer or the negative electrode active material layer is formed by applying a slurry and the positive electrode active material layer or the negative electrode active material layer is in a wet state, a slurry for forming the inorganic solid electrolyte layer is applied. The all-solid-state secondary battery according to claim 1, wherein the inorganic solid electrolyte layer is formed.
4. The all-solid-state secondary battery according to any one of claims 1 to 3, wherein the positive electrode active material layer and the negative electrode active material layer have a thickness of 1 µm to 1000 µm.
5. The all-solid-state secondary battery according to any one of claims 1 to 4, wherein the inorganic solid electrolyte layer has a thickness of 1 µm or more and 1000 µm or less.
6. 6. The maximum height roughness Rz of at least one of the interface between the positive electrode active material layer and the inorganic solid electrolyte layer or the negative electrode active material layer and the inorganic solid electrolyte layer is 3 μm or less. All-solid secondary battery.
7. The all-solid-state secondary battery according to any one of claims 1 to 6, wherein the inorganic solid electrolyte is a sulfide-based inorganic solid electrolyte.
8. The all-solid-state secondary battery according to any one of claims 1 to 6, wherein the inorganic solid electrolyte is an oxide-based inorganic solid electrolyte.
9. The all-solid-state secondary battery according to claim 8, wherein the inorganic solid electrolyte is selected from a compound represented by the following formula.
   · _Li x _La y TiO ₃
   x = 0.3 to 0.7, y = 0.3 to 0.7
   ・ Li ₇ La ₃ Zr ₂ O ₁₂
   ・ Li _3.5 Zn _0.25 GeO ₄
   LiTi ₂ P ₃ O ₁₂ ,
   Li _{1 + x + y} (Al, Ga) _x (Ti, Ge) ₂ -xSi _y P ₃ -yO ₁₂
   0 ≦ x ≦ 1, 0 ≦ y ≦ 1
   ・ Li ₃ PO ₄
   ・ LiPON
   ・ LiPOD
   D is Ti, V, Cr, Mn, Fe, Co, Ni, Cu,
   Zr, Nb, Mo, Ru, Ag, Ta, W, Pt, and Au
   At least one selected from LiAON
   A is at least one selected from Si, B, Ge, Al, C, Ga, etc.
10. 10. The all solid state secondary battery according to claim 1, wherein at least one of the positive electrode active material layer, the negative electrode active material layer, and the inorganic solid electrolyte layer contains a binder.
11. A manufacturing method for forming an inorganic solid electrolyte layer on a positive electrode active material layer or a negative electrode active material layer by a coating method,
    The step of applying a slurry for forming a positive electrode active material layer or a negative electrode active material layer on a current collector, while the obtained positive electrode active material layer or negative electrode active material layer is in a wet state, an inorganic solid electrolyte layer is formed. The manufacturing method of the electrode sheet for batteries which has the process of apply | coating the slurry for forming.
12. The method for producing a battery electrode sheet according to claim 11, wherein the application of the slurry of the positive electrode active material layer or the negative electrode active material layer and the application of the slurry of the inorganic solid electrolyte layer are performed simultaneously or sequentially.
13. A method for producing an all-solid-state secondary battery, comprising producing an all-solid-state secondary battery via the method for producing an electrode sheet for a battery according to claim 11 or 12.

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