Electrode composition, electrode sheet for all-solid-state secondary battery, all-solid-state secondary battery, and manufacturing method for the latter two

Abstract

This invention provides an electrode composition, an electrode sheet for an all-solid-state secondary battery using the electrode composition, an all-solid-state secondary battery, and a method for manufacturing the electrode sheet and the all-solid-state secondary battery. The electrode composition contains an inorganic solid electrolyte, an active material, a polymer binder comprising a linear polymer, and a dispersion medium. The radius of gyration α of the polymer binder and the equivalent median diameter D of the inorganic solid electrolyte and the active material are specified. 50 With the radius of rotation α as the x-axis and the median diameter D as the x-axis... 50 The region located within a polygon with vertices A to E in an orthogonal coordinate system with the y-axis is included, including the region on the boundary line.

Description

TECHNICAL FIELD

[0001] The present application relates to an electrode composition, an electrode sheet for a full solid-state secondary battery, and a full solid-state secondary battery, and a method for manufacturing an electrode sheet for a full solid-state secondary battery and a full solid-state secondary battery. BACKGROUND

[0002] A negative electrode, an electrolyte, and a positive electrode of a full solid-state secondary battery are all composed of solids, and it is possible to greatly improve safety or reliability, which are issues of secondary batteries using organic electrolytic solutions. Also, it is possible to extend the life. Furthermore, a full solid-state secondary battery can be configured in a structure in which electrodes and electrolytes are directly arranged and connected in series. Therefore, compared with a secondary battery using an organic electrolytic solution, it is possible to be high in energy density, and it is expected to be applied to electric vehicles or large-scale storage batteries, and the like.

[0003] In such a full solid-state secondary battery, as a substance forming a constituent layer (a solid electrolyte layer, a negative electrode active material layer, a positive electrode active material layer, or the like), an inorganic solid electrolyte, an active material such as a negative electrode active material or a positive electrode active material, or the like can be cited. Among them, an inorganic solid electrolyte, particularly, an oxide-based inorganic solid electrolyte and a sulfide-based inorganic solid electrolyte have been expected in recent years as an electrolyte material having high ion conductivity close to that of an organic electrolytic solution.

[0004] Therefore, in order to achieve high ion conductivity required as a basic performance of a full solid-state secondary battery, as a material forming a negative electrode active material layer or a positive electrode active material layer, a material containing the above-described inorganic solid electrolyte and an active material has been proposed. For example, in Patent Literature 1, "a slurry containing a solid electrolyte and a specific polymer" is described, as the "specific polymer", a "hydrogenated block copolymer composed of (A) a block composed of polybutadiene having a 1,2-vinyl bond content of 15% or less and (B) a block composed of butadiene (co)polymer having a 1,2-vinyl bond content of 20 to 90% in the butadiene portion at 50 to 100% by weight and other monomers at 0 to 50% by weight, and a linear or branched block copolymer at a weight ratio of (A) / (B) = 5 / 95 to 70 / 30 is hydrogenated" is used. Also, in Patent Literature 2, "a solid electrolyte composition containing a dendritic polymer selected from at least one of a dendron, a dendritic polymer, and a hyperbranched polymer, and an inorganic solid electrolyte having ion conductivity of a metal belonging to Group 1 or Group 2 of the periodic table" is described, and the dendritic polymer has a specific functional group.

[0005] PRIOR ART DOCUMENTS

[0006] PATENT LITERATURE

[0007] Patent Literature 1: Japanese Patent Application Laid-Open No. 11-086899

[0008] Patent Literature 2: International Publication No. 2017 / 018456 A1 SUMMARY

[0009] Technical Problem to be Solved by the Invention

[0010] However, in the constitution layer constituted by solid particles such as inorganic solid electrolyte, active material, and conductive aid, the interface contact state of the solid particles to each other is limited. Therefore, even if the solid particles constituting the constitution layer themselves can exhibit high ion conductivity, the electron conductivity and ion conductivity are reduced due to the increase in the interface resistance of the solid particles, and thus a large current cannot be extracted (discharged) from the all-solid-state secondary battery.

[0011] When an active material layer is formed using a material containing an inorganic solid electrolyte and an active material (also referred to as an electrode material), if the electrode material is film-formed on a substrate in the conventional electrode material, the coated electrode material can cause liquid dripping (a phenomenon in which the electrode material flows and causes the shape of the end edge of the coated layer to collapse (thickness reduction)). This liquid dripping is likely to occur near the widthwise both end edges of the electrode material coated in a sheet shape. In order to suppress the occurrence of this liquid dripping, it is effective to increase the viscosity (concentration) of the electrode material, but this can cause coating unevenness (unevenness of layer thickness) to occur on the coated layer of the electrode material. This coating unevenness is likely to occur near the widthwise center of the electrode material coated in a sheet shape.

[0012] In recent years, development toward practical use of all-solid-state secondary batteries has been rapidly progressing, and as a countermeasure corresponding thereto, it is desired to improve both the battery performance (high energy density) and the industrial manufacturing of all-solid-state secondary batteries. With respect to the high energy density of all-solid-state secondary batteries, it is effective to make the layer thickness of the active material layer thicker, and as a means thereof, for example, film formation is performed by increasing the coating amount of the electrode material or increasing the solid component concentration. In the film formation of the layer-thickened active material layer, if the electrode material can be film-formed in one film formation process, it is advantageous from the viewpoint of industrial manufacturing. However, if the coating amount of the conventional electrode material or the conventional electrode material having an increased solid component concentration is increased, liquid dripping or coating unevenness is significantly generated, and in the film formation method in which the electrode material is coated and dried on a substrate, particularly in the film formation method in which a roll to roll method capable of continuously film-forming in a sheet shape is applied, it is difficult to obtain a prescribed shape of the active material layer that is uniform and thick-layered (thick-filmed).

[0013] As described above, in addition to improving the ion conductivity which is a basic performance of the all-solid-state secondary battery, there is a demand for an electrode material which can suppress the generation of liquid droplets and the generation of coating unevenness even when applied to a film formation method. However, this point is not described in Patent Literatures 1 and 2.

[0014] An object of the present application is to provide an electrode composition which can suppress the generation of liquid droplets and coating unevenness at the time of film formation, and can form an active material layer which can exhibit high ion conductivity. Furthermore, an object of the present application is to provide an electrode sheet for an all-solid-state secondary battery and an all-solid-state secondary battery using the electrode composition, and a manufacturing method of an electrode sheet for an all-solid-state secondary battery and an all-solid-state secondary battery.

[0015] Means for solving the technical problem

[0016] The present inventors and others have conducted research focusing on the relationship between the inorganic solid electrolyte, the active material, and the polymer binder used in the electrode composition from the viewpoint of improving the coating properties (liquid droplets and coating unevenness) of the electrode composition and the constructability of the conduction path formed by solid particles when the electrode composition is used as an active material layer. As a result, it was found that by setting the overall particle diameter (median diameter D 50 ) of the inorganic solid electrolyte and the active material dispersed in the electrode composition and adhered in the active material layer and the radius of gyration α of the polymer binder composed of a linear polymer within a specific range described below, it is possible to simultaneously suppress the generation of liquid droplets and the generation of coating unevenness of the electrode composition at the time of film formation, and to construct a sufficient ion conduction path between the solid particles. The present application was further developed based on these insights through repeated research, and thus the present application was completed.

[0017] That is, the above-described object is solved by the following solutions.

[0018] <1> An electrode composition containing an inorganic solid electrolyte having ion conductivity of an ion of a metal belonging to Group 1 or Group 2 of the periodic table, an active material, a polymer binder, and a dispersion medium, wherein

[0019] The above-described polymer binder is composed of a linear polymer,

[0020] The radius of gyration α of the above-described polymer binder in the above-described dispersion medium and the median diameter D 50 In the above-described radius of gyration α is the x-axis, and the above-described median diameter D 50in a rectangular coordinate system with the y axis, in a region of a polygon having A point (50, 60), B point (178, 4600), C point (85, 4600), D point (12, 2000), and E point (12, 60) as vertices, wherein the boundary line is included.

[0021] <2> The electrode composition according to <1>, wherein

[0022] The SP value of the linear polymer is 16 to 20 MPa 1 / 2 .

[0023] <3> The electrode composition according to <1> or <2>, wherein

[0024] The adsorption rate of the polymer binder to the active material in the dispersion medium is 40% or less.

[0025] <4> The electrode composition according to any one of <1> to <3>, wherein

[0026] The linear polymer contains a constituent component having a functional group with pKa of 8 or less.

[0027] <5> The electrode composition according to any one of <1> to <4>, wherein

[0028] The polymer binder is dissolved in the dispersion medium.

[0029] <6> The electrode composition according to any one of claims 1 to 5, wherein

[0030] The active material has silicon element as a constituent element.

[0031] <7> The electrode composition according to any one of <1> to <6>, wherein

[0032] The inorganic solid electrolyte is a sulfide-based inorganic solid electrolyte.

[0033] <8> The electrode composition according to any one of <1> to <7>, wherein

[0034] The SP value of the dispersion medium is 14 to 24 MPa 1 / 2 .

[0035] <9> An electrode sheet for a full solid-state secondary battery, having a layer composed of the electrode composition according to any one of <1> to <8> on the surface of a substrate.

[0036] <10> A full solid-state secondary battery sequentially having a positive electrode active material layer, a solid electrolyte layer, and a negative electrode active material layer,

[0037] At least one of the positive electrode active material layer and the negative electrode active material layer is a layer composed of the electrode composition described in any one of <1> to <8> above.

[0038] <11> A method for manufacturing an electrode sheet for an all-solid-state secondary battery, wherein the electrode composition described in any one of <1> to <8> is filmed on the surface of a substrate.

[0039] <12> A method for manufacturing an all-solid-state secondary battery, wherein the all-solid-state secondary battery is manufactured by the manufacturing method described in <11> above.

[0040] Invention Effects

[0041] This invention provides an electrode composition capable of suppressing liquid dripping and uneven coating during film formation, and capable of forming an active material layer exhibiting high ionic conductivity. Furthermore, this invention provides an electrode sheet for an all-solid-state secondary battery having an active material layer composed of this electrode composition, and an all-solid-state secondary battery. Additionally, this invention provides a method for manufacturing an electrode sheet for an all-solid-state secondary battery and an all-solid-state secondary battery using this electrode composition.

[0042] The above-described features and other features and advantages of the present invention will become more apparent from the accompanying drawings and from the following description. Attached Figure Description

[0043] Figure 1 This is a longitudinal sectional view illustrating a preferred embodiment of the all-solid-state secondary battery of the present invention.

[0044] Figure 2 This is a schematic longitudinal sectional view of the button-shaped all-solid-state secondary battery manufactured in the embodiment.

[0045] Figure 3 This indicates the median diameter D in this invention. 50 A graph showing the relationship between the rotation radius α and the rotation radius α.

[0046] Figure 4 This is a diagram illustrating the area where the layer thickness was measured in the uneven coating test of the embodiment. Detailed Implementation

[0047] In this invention, the numerical range indicated by "~" refers to the range encompassed by the values ​​recorded before and after "~" as the lower and upper limits. Furthermore, in this invention, when multiple numerical ranges are defined to describe the content, physical properties, etc., of a component, the upper and lower limits of the numerical range are not limited to specific combinations of upper and lower limits, but can be defined as numerical ranges formed by appropriately combining the upper and lower limits of each numerical range.

[0048] In this invention, the designation of a compound (e.g., when referred to as a compound by appending a compound at the end) means that in addition to the compound itself, it also includes its salt and its ions. Furthermore, it refers to derivatives that include modifications to the introduced substituents or other components without impairing the effects of this invention.

[0049] In this invention, (meth)acrylic acid refers to one or both of acrylic acid and methacrylic acid. The same applies to (meth)acrylates.

[0050] In this invention, the term "substituent, linking group, etc." (hereinafter referred to as "substituent, etc.") that is not explicitly stated as substituted or unsubstituted means that the group may also have suitable substituents. Therefore, in this invention, even when simply described as a YYY group, the YYY group includes not only those without substituents but also those with substituents. This also applies to compounds where substitution or unsubstituent is not explicitly stated. As a preferred substituent, substituent Z, described later, can be cited as an example.

[0051] In this invention, when multiple substituents, etc., are represented by specific symbols, or when multiple substituents, etc., are specified simultaneously or selectively, it means that each substituent, etc., may be the same as or different from each other. Furthermore, even without special explanation, when multiple substituents, etc., are adjacent, it means that they may be linked together or fused together to form a ring.

[0052] In this invention, "polymer" refers to a polymer, but it has the same meaning as "high molecular weight compound". Furthermore, "polymer adhesive" (also simply "adhesive") refers to an adhesive composed of polymers, including the polymer itself and adhesives formed by containing polymers.

[0053] In this invention, a composition containing an inorganic solid electrolyte and an active material and used as a material for forming the active material layer of an all-solid-state secondary battery (active material layer forming material) is referred to as an electrode composition. On the other hand, a composition containing an inorganic solid electrolyte and used as a material for forming the solid electrolyte layer of an all-solid-state secondary battery is referred to as an inorganic solid electrolyte-containing composition, which typically does not contain an active material.

[0054] In this invention, the electrode composition comprises a positive electrode composition containing a positive electrode active material and a negative electrode composition containing a negative electrode active material. Therefore, sometimes either or both of the positive electrode composition and the negative electrode composition are simply referred to as the electrode composition, and sometimes either or both of the positive electrode active material layer and the negative electrode active material layer are simply referred to as the active material layer or the electrode active material layer. Furthermore, either or both of the positive electrode active material and the negative electrode active material are collectively referred to simply as the active material or the electrode active material.

[0055] [Electrode Composition]

[0056] The electrode composition of the present invention contains an inorganic solid electrolyte having ionic conductivity of a metal belonging to Group 1 or Group 2 of the periodic table, an active material, a polymer binder, and a dispersion medium.

[0057] In the electrode composition of the present invention, the median diameter D is obtained by considering the radius of rotation α of the polymer binder composed of linear polymers, the dispersion medium, and the median diameters of the inorganic solid electrolyte (particles) and active material (particles) calculated based on their content (mass fraction) in the electrode composition. 50 Satisfy Figure 3 As shown, with the radius of rotation α as the x-axis and the median diameter D as the x-axis... 50 The relationship exists within a pentagonal region (including the boundary lines) with 5 specific points A to E as vertices in an orthogonal coordinate system with the y-axis as described later. The electrode composition of the present invention, satisfying this relationship, can suppress liquid dripping and uneven coating during film formation, and can form an active material layer exhibiting high ionic conductivity. Furthermore, by using this electrode composition as the active material layer forming material, even in film-forming methods, it is possible to achieve an all-solid-state secondary battery electrode sheet with a uniform layer thickness and a defined shape on the substrate surface, and an all-solid-state secondary battery exhibiting high ionic conductivity (low resistance).

[0058] The detailed reasons are still unclear, but the following is believed.

[0059] That is, the polymer adhesive is composed of linear polymers and satisfies the median diameter D described later. 50 The relationship with the radius of rotation α ensures that the surface of solid particles such as inorganic solid electrolytes and active materials is not excessively coated in the electrode composition. When used as an active material layer, it ensures contact between solid particles and establishes sufficient conduction paths. Furthermore, because the inorganic solid electrolyte, active material, and polymer binder satisfy the median diameter D... 50 The relationship with the radius of rotation α allows for a balanced setting of the size and number (number of molecules per mass) of the polymer binder relative to the inorganic solid electrolyte and active material. This improves the dispersibility of the inorganic solid electrolyte and active material and reduces excessive interaction between the polymer binders. Consequently, by suppressing excessive viscosity increases in the electrode composition, a balanced approach can be taken between flowability during coating and non-flowability after coating.

[0060] Thus, the electrode composition of the present invention suppresses liquid dripping and uneven coating during film formation, and can form an active material layer with uniform thickness, a specified shape, and high ionic conductivity even in film-forming methods. Furthermore, in this electrode composition, the inorganic solid electrolyte, active material, and polymer binder satisfy the median diameter D... 50 The relationship with the radius of rotation α means that even if the content of inorganic solid electrolyte and active material is increased, the fluidity during coating and the non-fluidity after coating can be maintained. Therefore, even with a thick active material layer, or through film-forming methods such as the high-productivity roll-to-roll method, an active material layer with uniform thickness and a specified shape can be formed.

[0061] The electrode composition of the present invention should satisfy the above-mentioned median diameter D. 50 The relationship with the radius of rotation α is explained.

[0062] The radius of gyration α in the dispersion medium of an electrode composition comprising a polymer binder consisting of linear polymers refers to the size of the polymer binder (linear polymer molecules) in that dispersion medium, and the median diameter D. 50 This refers to the overall size of the inorganic solid electrolyte and active material in the electrode composition and the active material layer formed therefrom, where the polymer binder functions. Furthermore, in the electrode composition, the radius of gyration α also represents the number of polymer binders present per unit mass, and the median diameter D... 50 It also represents the total number of inorganic solid electrolytes and active substances per unit mass.

[0063] Furthermore, in this invention, by satisfying the above-mentioned relationships, the size of the polymer binder and the size of the inorganic solid electrolyte and active material, as well as the number of polymer binders, inorganic solid electrolytes and active materials per unit mass, are set in a balanced manner. As described above, this allows for the balance between the high ionic conductivity in the active material layer and the fluidity during coating and the non-fluidity after coating in the electrode composition.

[0064] Rotation radius α and median diameter D 50 exist Figure 3 In the orthogonal coordinate system shown, the following relationship exists within the pentagonal region (including the boundary lines) with vertices A(50, 60), B(178, 4600), C(85, 4600), D(12, 2000), and E(12, 60). The rotation radius α and the median diameter D... 50 Within the aforementioned region, as described above, an active material layer exhibiting high ionic conductivity can be formed while suppressing liquid dripping and uneven coating of the electrode composition. In contrast, if the radius of rotation α and the median diameter D... 50Outside of the aforementioned regions, it is not possible to simultaneously suppress liquid dripping and uneven coating of the electrode composition, as well as improve ionic conductivity. This is explained in detail below.

[0065] If it lies on the line connecting points A and B (for example, D), 50 =35α-1700) On the inner side of the above-mentioned area (including the straight line. The same applies below.), the effect of improving coating unevenness is excellent. If it is on the outer side, the effect of improving coating unevenness and ion conductivity is poor.

[0066] If the line connecting points B and C is located at (D) 50 =4600) On the inner side of the above-mentioned area, it shows the effect of suppressing the generation of uneven coating and liquid dripping. In particular, the size of the inorganic solid electrolyte and active material becomes the size of its surface when appropriately coated with polymer adhesive, and the ionic conductivity is greatly improved.

[0067] If the line connecting points C and D is located (for example, D...), then... 50 =36α+1600) The inner side of the above-mentioned region has a particularly good effect on improving liquid droplet flow and ion conductivity, while the outer side has a poor effect on improving liquid droplet flow and ion conductivity.

[0068] If the polymer adhesive is located inside the region of the line connecting points D and E (α = 12), the size of the polymer adhesive becomes the size of the surface that can properly coat the inorganic solid electrolyte and active material. While maintaining the effect of suppressing liquid dripping and uneven coating, it can also particularly improve the ion conductivity.

[0069] If the line connecting points E and A is located at (D) 50 =60) On the inner side of the above-mentioned region, the size of the inorganic solid electrolyte and active material becomes the size of its surface when appropriately coated with polymer adhesive, especially with excellent improvement in ionic conductivity.

[0070] In this invention, the radius of rotation α and the median diameter D 50 The region in the aforementioned orthogonal coordinate system that satisfies this condition can be defined as a polygonal region (including the boundary lines) in which at least one of the aforementioned five points is replaced by one or more points other than the aforementioned five points. Within this region, liquid dripping and uneven coating can be suppressed, and ionic conductivity can be improved.

[0071] From the perspective of achieving a higher level of uniformity in the liquid droplet formation of the electrode composition, suppressing uneven coating, and improving ionic conductivity, the radius of rotation α and the median diameter D... 50 exist Figure 3In the orthogonal coordinate system shown, the preferred location is within the hexagonal region with vertices A, F (85, 2800), C, G (37, 2800), D, and E (including the boundary lines). The straight line connecting points A and F is, for example, from D... 50 =78α-3900 represents this.

[0072] Rotation radius α and median diameter D 50 More preferably, it is located within the region of a pentagon with vertices A, F, G, D, and E (including the boundary lines). Even more preferably, it is located within the region of a quadrilateral with vertices A, H (50, 2000), D, and E (including the boundary lines). Particularly preferably, it is located within the region of a quadrilateral with vertices J (50, 900), H, D, and I (12, 900) (including the boundary lines).

[0073] When the electrode composition contains a positive electrode active material as the active material, as long as the radius of rotation α and the median diameter D are... 50 Within the aforementioned regions, an active material layer can be formed that suppresses liquid dripping and uneven coating of the electrode composition while exhibiting high ionic conductivity.

[0074] However, it is also possible to set it as the areas specified below.

[0075] exist Figure 3 In the orthogonal coordinate system shown, the radius of rotation α and the median diameter D 50 The region lies within the pentagon with vertices AP (50, 120), BP (172, 4500), CP (85, 4500), DP (16, 1600), and EP (16, 120) (including the boundary lines). Here, the straight line connecting AP and BP is, for example, represented by D... 50 =36α-1700 represents the straight line connecting points CP and DP, for example, represented by D. 50 =42α+930 represents the pentagon. The meaning of the straight line connecting two of the five points that define the pentagon is the same as that of points A to E above.

[0076] In this region, it is also possible to define a polygonal region formed by replacing at least one of the above 5 points with one or more points other than the above 5 points in the region.

[0077] From the viewpoint of achieving a higher level of uniformity in liquid droplet generation and coating unevenness of the electrode composition, as well as improving ionic conductivity, a preferred region in an orthogonal coordinate system can be the hexagonal region (including the boundary lines) with vertices AP, FP (85, 2700), CP, GP (37, 2600), DP, and EP. Here, the straight line connecting AP and FP is, for example, represented by D... 50 =74α-3600 represents this.

[0078] In the positive electrode composition, the radius of rotation α and the median diameter D 50 More preferably, it is located within the region of a pentagon with vertices AP, FP, GP, DP, and EP (including the boundary lines). More preferably, it is located within the region of a polygon with vertices AP, HP (50, 1600), DP, and EP (including the boundary lines).

[0079] There are no particular restrictions on the rotation radius α as long as the above relationship is satisfied. For example, the rotation radius α is relative to the median diameter D of the range described later. 50 Preferably, the value is 12 or higher, more preferably 16 or higher, even more preferably 20 or higher, and especially preferably 25 or higher. On the other hand, the upper limit is preferably 178 or lower, more preferably 172 or lower, even more preferably 140 or lower, especially preferably 100 or lower, and most preferably 70 or lower.

[0080] The radius of gyration α can be determined using the following polymer binder solutions. Specifically, using a static light scattering apparatus (DLS-8000, manufactured by Otsuka Electronics Co., Ltd., laser wavelength λ = 632.8 nm), the scattering intensity I at scattering angles θ = 50°, 60°, 70°, 80°, 90°, 100°, 110°, 120°, and 130° is measured for the polymer binder solution (polymer concentrations at four points, e.g., c = 0.25 mg / mL, 0.50 mg / mL, 0.75 mg / mL, and 1.00 mg / mL), the dispersion medium, and toluene. soln I solv I tol The excess Rayleigh ratio is calculated using the following formula.

[0081] Based on the obtained excess Rayleigh ratio R θ Furthermore, a Zimm plot is constructed based on the following equation (I), and q is obtained by extrapolating the polymer concentration c to zero concentration (c→0). 2 The slope is evaluated to calculate the radius of rotation α.

[0082] In the following formula, n and δn / δc are the refractive index of the polymer adhesive solution and its concentration change rate, respectively, which can be determined, for example, using a differential refractometer (DRM-3000, manufactured by Otsuka Electronics Co., Ltd.). tol and R tol M represents the refractive index and Rayleigh ratio of toluene, for example, values ​​known from reference [1] (ERPike, WRMPomeroy, JMVaughan, J. Chem. Phys., 62 (1975), 3188-3192). q is the scattering vector, and k is the optical constant, defined by the following formulas. w To determine the mass-average molecular weight and N of the polymer of the target object. A O(q) is Avogadro's constant. A2 is the second virial coefficient. In this determination, O(q) 4 ) and O(c 2 The value is negligible due to its small size. The polymer binder solution is prepared by dissolving the polymer of the test object in a dispersion medium (butyl butyrate in the examples) used to prepare the electrode composition.

[0083] [Formula 1]

[0084] Excess Rayleigh

[0085] Formula (I):

[0086]

[0087] The radius of rotation α of a polymer binder can be appropriately adjusted based on the molecular structure (linear), mass-average molecular weight, presence or absence of functional groups below pKa8 (described later), the content of the polymer containing such functional groups, and the SP value of the polymer forming the binder (usually a linear polymer). For example, to increase the radius of rotation α, one can increase the mass-average molecular weight, introduce functional groups below pKa8, and further set the difference between the SP value of the polymer binder and the SP value of the dispersion medium to 2 or less.

[0088] Median diameter D 50 There are no special restrictions as long as the above relationship is satisfied. For example, the median path D 50 The radius of rotation α relative to the above range is preferably 60 nm or more, more preferably 300 nm or more, and even more preferably 500 nm or more. On the other hand, its upper limit is preferably 4600 nm or less, more preferably 4500 nm or less, even more preferably 3000 nm or less, particularly preferably 2000 nm or less, and most preferably 1500 nm or less.

[0089] Median diameter D 50 Let's assume that the median diameter D of the inorganic solid electrolyte is determined using the method described later. S-50 Median diameter D of active substances A-50 The value calculated by the following formula will be rounded to a value with two significant digits.

[0090] Median diameter D 50 =(D S-50 ×W S )+(D A-50 ×W A )

[0091] In the formula, D S-50 D represents the median diameter of inorganic solid electrolytes. A-50 This represents the median diameter of the active substance. W S and W A The mass fractions of the inorganic solid electrolyte and the active material, respectively, represent the total mass of the inorganic solid electrolyte and the active material in the electrode composition.

[0092] The electrode composition of the present invention is preferably a slurry in which inorganic solid electrolyte and active material are dispersed in a dispersion medium in the form of particles.

[0093] In the electrode composition of the present invention, the polymer binder preferably exhibits the function of dispersing the inorganic solid electrolyte and the active material in the dispersion medium. Furthermore, there is no particular limitation on whether the polymer binder adsorbs onto the inorganic solid electrolyte, but it is preferable that it adsorbs onto the active material within a range that satisfies the adsorption rate described later. This allows for improved dispersibility without excessively coating the surface of the active material.

[0094] On the other hand, the polymer binder functions as a binder in the active material layer, bonding together solid particles such as the active material, inorganic solid electrolyte, and even coexisting conductive additives. It also functions as a binder for bonding current collectors and solid particles. In the electrode composition, the polymer binder may not have the function of bonding solid particles together.

[0095] In the electrode composition of the present invention, the viscosity (initial viscosity) after preparation is not particularly limited. In the present invention, since the electrode composition contains an inorganic solid electrolyte, an active material, and a polymer binder that satisfy the above-mentioned relationship, from the viewpoint of achieving coating properties without liquid dripping and uneven coating, the viscosity in the following measurement conditions is preferably 300 to 4000 cP, more preferably 800 to 4000 cP.

[0096] -Determination Conditions-

[0097] Temperature: 23℃

[0098] Shear rate: 10 / s

[0099] Measurement equipment: TV-35 viscometer (manufactured by Toki Sangyo Co., Ltd.)

[0100] Measurement method: Add 1.1 ml of the composition to the sample cup, place the sample cup on the viscometer body equipped with a standard conical rotor (1°34'×R24), set the measurement range to "U", rotate at the above shear rate and read the value after 1 minute.

[0101] The electrode composition of the present invention is preferably a non-aqueous composition. In the present invention, the non-aqueous composition includes not only a water-free state but also a water content (also referred to as moisture content) preferably of 500 ppm or less. In the non-aqueous composition, the water content is more preferably 200 ppm or less, further preferably 100 ppm or less, and particularly preferably 50 ppm or less. If the electrode composition is a non-aqueous composition, the degradation of the inorganic solid electrolyte can be suppressed. The water content refers to the amount of water contained in the electrode composition (mass ratio of the electrode composition), specifically, a value obtained by filtration using a 0.02 μm membrane filter and determination using Karl Fischer titration.

[0102] The electrode composition of the present invention is preferably used as an electrode sheet for all-solid-state secondary batteries or as a material for forming the active material layer of all-solid-state secondary batteries. In particular, it is preferably used as a material for forming a negative electrode sheet or negative electrode active material layer for all-solid-state secondary batteries, which contains a negative electrode active material that expands and contracts significantly due to charging and discharging.

[0103] The components contained in the electrode composition of the present invention and the components that may be contained therein are described below.

[0104] <Inorganic Solid Electrolytes>

[0105] The ground electrode composition of the present invention contains an inorganic solid electrolyte.

[0106] In this invention, inorganic solid electrolyte refers to an inorganic solid electrolyte, which is a solid electrolyte capable of allowing ions to move within it. It is clearly distinguished from organic solid electrolytes (such as polymeric electrolytes represented by polyethylene oxide (PEO) and organic electrolyte salts represented by lithium bis(trifluoromethanesulfonyl)imide (LiTFSI)) from the perspective of not containing organic materials as the primary ion-conducting material. Furthermore, since inorganic solid electrolytes are solid in their stable state, they generally do not dissociate or ionize into cations and anions. In this respect, they are clearly distinguished from inorganic electrolyte salts (such as LiPF6, LiBF4, lithium bis(fluorosulfonyl)imide (LiFSI), and LiCl) that dissociate or ionize into cations and anions in electrolytes or polymers. There are no particular limitations as long as the inorganic solid electrolyte possesses the ion conductivity of metals belonging to Group 1 or Group 2 of the periodic table; it generally does not possess electronic conductivity. In the case of the all-solid-state secondary battery of the present invention being a lithium-ion battery, it is preferable that the inorganic solid electrolyte has the ionic conductivity of lithium ions.

[0107] The inorganic solid electrolyte contained in the electrode composition of the present invention is in particulate form, at least in the electrode composition. The shape of the particles is not particularly limited and can be flat, amorphous, etc., but preferably spherical or granular.

[0108] Particle size (volume average particle size: median diameter) of inorganic solid electrolytes D S-50 As long as the median diameter D is satisfied 50 There are no special restrictions, and they can be set appropriately. D S-50 For example, a depth of 0.01 μm or more is preferred, 0.05 μm or more is more preferred, 1.4 μm or more is even more preferred, and 2.7 μm or more is particularly preferred. As D S-50 The upper limit of the size is preferably 4.5 μm or less, more preferably 4.0 μm or less, further preferably 3.2 μm or less, especially preferably 2.1 μm or less, and most preferably 1.9 μm or less.

[0109] The particle size of the inorganic solid electrolyte was determined using the following steps. A 1% (w / w) dispersion of the inorganic solid electrolyte particles was prepared by diluting the particles with water (or heptane in the case of substances unstable in water) in a 20 mL sample vial. The diluted dispersion sample was then irradiated with ultrasound at 1 kHz for 10 minutes and immediately used in the experiment. Using this dispersion sample, 50 data acquisitions were performed using a laser diffraction / scattering particle size distribution measuring device LA-920 (trade name, manufactured by HORIBA, Ltd.) at 25°C using a measuring quartz cell, thereby obtaining the volume average particle size D. S-50Other detailed conditions should be referred to the Japanese Industrial Standard (JIS) Z8828:2013 "Particle Size Analysis - Dynamic Light Scattering Method" as needed. Five samples should be prepared for each grade and their average value should be used.

[0110] When the electrode composition contains two or more inorganic solid electrolytes, the actual median diameter D of the mixture can also be determined by the above method. S-50 However, in this invention, the median diameter of each inorganic solid electrolyte is measured by the above method and calculated according to the following formula.

[0111] Median diameter D S-50 =D S1-50 ×W S1 +D S2-50 ×W S2 +……

[0112] In the formula, D S1-50 D S2-50 ...represents the median diameter of inorganic solid electrolytes, W S1 W S2 ...represents the mass fraction relative to the total volume of the inorganic solid electrolyte.

[0113] There are no particular limitations on the method for adjusting the average particle size; well-known methods can be used, such as using a conventional pulverizer or classifier. For example, suitable pulverizers or classifiers include mortars, ball mills, sand mills, vibratory ball mills, satellite ball mills, planetary ball mills, rotary air jet mills, and sieves. During pulverization, wet pulverization with a dispersion medium such as water or methanol can be appropriately performed. To achieve the desired particle size, classification is preferred. Classification is not particularly limited; sieves, air classifiers, etc., can be used. Both dry and wet classification methods can be used.

[0114] The aforementioned inorganic solid electrolyte can be appropriately selected from solid electrolyte materials commonly used in all-solid-state secondary batteries. For example, as inorganic solid electrolytes, (i) sulfide-based inorganic solid electrolytes, (ii) oxide-based inorganic solid electrolytes, (iii) halide-based inorganic solid electrolytes, and (iv) hydride-based inorganic solid electrolytes can be mentioned. From the viewpoint of forming a better interface between the active material and the inorganic solid electrolyte, sulfide-based inorganic solid electrolytes are preferred.

[0115] (i) Sulfide-based inorganic solid electrolytes

[0116] The preferred form is a sulfide-based inorganic solid electrolyte containing sulfur atoms, possessing ionic conductivity of a metal belonging to Group 1 or Group 2 of the periodic table, and exhibiting electronic insulation properties. The preferred form is a sulfide-based inorganic solid electrolyte containing at least Li, S, and P as elements, and exhibiting lithium-ion conductivity; however, it may also appropriately contain other elements besides Li, S, and P.

[0117] As a sulfide-based inorganic solid electrolyte, for example, a lithium-ion conductive inorganic solid electrolyte that satisfies the composition represented by the following formula (S1) can be cited.

[0118] L a1 M b1 P c1 S d1 A e1 (S1)

[0119] In the formula, L represents an element selected from Li, Na, and K, preferably Li. M represents an element selected from B, Zn, Sn, Si, Cu, Ga, Sb, Al, and Ge. A represents an element selected from I, Br, Cl, and F. a1 to e1 represent the composition ratio of each element, where a1:b1:c1:d1:e1 satisfies 1–12:0–5:1:2–12:0–10. a1 is preferably 1–9, more preferably 1.5–7.5. b1 is preferably 0–3, more preferably 0–1. d1 is preferably 2.5–10, more preferably 3.0–8.5. e1 is preferably 0–5, more preferably 0–3.

[0120] As described below, the composition ratio of each element can be controlled by adjusting the amount of raw material compounds used in the manufacture of sulfide-based inorganic solid electrolytes.

[0121] Sulfide-based inorganic solid electrolytes can be amorphous (glass), crystallized (glass-ceramic), or partially crystallized. For example, Li-PS-based glasses or Li-PS-based glass-ceramics containing Li, P, and S can be used.

[0122] Sulfide-based inorganic solid electrolytes can be manufactured by reacting at least two of the following raw materials: lithium sulfide (Li2S), phosphorus sulfide (e.g., phosphorus pentasulfide (P2S5)), monomeric phosphorus, monomeric sulfur, sodium sulfide, hydrogen sulfide, lithium halides (e.g., LiI, LiBr, LiCl), and sulfides of the element represented by M above (e.g., SiS2, SnS, GeS2).

[0123] The ratio of Li₂S to P₂S₅ in Li-PS-based glasses and Li-PS-based glass ceramics is preferably 60:40 to 90:10, more preferably 68:32 to 78:22, in terms of the molar ratio of Li₂S:P₂S₅. Setting the Li₂S to P₂S₅ ratio within this range improves lithium-ion conductivity. Specifically, the lithium-ion conductivity is preferably set to 1 × 10⁻⁶. -4 S / cm or higher, more preferably 1×10 -3 S / cm or higher. Although no specific upper limit is set, it is actually 1×10⁻⁶. -1 Below S / cm.

[0124] As specific examples of sulfide-based inorganic solid electrolytes, combinations of raw materials are illustrated below. For example, Li₂S-P₂S₅, Li₂S-P₂S₅-LiCl, Li₂S-P₂S₅-H₂S, Li₂S-P₂S₅-H₂S-LiCl, Li₂S-LiI-P₂S₅, Li₂S-LiI-Li₂O-P₂S₅, Li₂S-LiBr-P₂S₅, Li₂S-Li₂O-P₂S₅, Li₂S-Li₃PO₄-P₂S₅, Li₂S-P₂S₅-P₂O₅, Li₂S-P₂S₅-SiS₂, Li₂S-P₂S₅-SiS₂-LiCl, Li₂S-P₂S₅-SnS, and Li₂S-P₂S₅-Al₂ can be cited. S3, Li2S-GeS2, Li2S-GeS2-ZnS, Li2S-Ga2S3, Li2S-GeS2-Ga2S3, Li2S-GeS2-P2S5, Li2S-GeS2-Sb2S5, Li2S-GeS2-Al2S3, Li2S-SiS2, Li2S-Al2S3, Li2S-SiS2-Al2S3, Li2S-SiS2-P2S5, Li2S-SiS2-P2S5-LiI, Li2S-SiS2-LiI, Li2S-SiS2-Li4SiO4, Li2S-SiS2-Li3PO4, Li 10 GeP2S 12 And so on. The mixing ratio of each raw material is not limited. As a method for synthesizing sulfide-based inorganic solid electrolyte materials using this raw material composition, for example, an amorphization method can be mentioned. As an amorphization method, examples include mechanical polishing, solution processing, and melt quenching. Processing at room temperature is possible, thereby simplifying the manufacturing process.

[0125] (ii) Oxide-based inorganic solid electrolytes

[0126] Oxide-based inorganic solid electrolytes are preferably compounds containing oxygen atoms, possessing ionic conductivity of metals belonging to Group 1 or Group 2 of the periodic table, and having electronic insulation properties.

[0127] For oxide-based inorganic solid electrolytes, the preferred ionic conductivity is 1×10⁻⁶. -6 S / cm or higher, preferably 5×10 -6 S / cm or higher, especially preferably 1×10 -5 S / cm or higher. Although there is no specific upper limit, it is actually 1×10 -1 Below S / cm.

[0128] As a specific example of a compound, Li can be cited. xa La ya TiO3 [xa satisfies 0.3≤xa≤0.7, ya satisfies 0.3≤ya≤0.7.] (LLT); Li xb La yb Zr zb M bb mb O nb (M bb It consists of one or more elements selected from Al, Mg, Ca, Sr, V, Nb, Ta, Ti, Ge, In, and Sn. xb satisfies 5 ≤ ​​xb ≤ 10, yb satisfies 1 ≤ yb ≤ 4, zb satisfies 1 ≤ zb ≤ 4, mb satisfies 0 ≤ mb ≤ 2, and nb satisfies 5 ≤ ​​nb ≤ 20. Li xc B yc M cc zc O nc (M cc It is an element selected from C, S, Al, Si, Ga, Ge, In, and Sn. xc satisfies 0 < xc ≤ 5, yc satisfies 0 < yc ≤ 1, zc satisfies 0 < zc ≤ 1, and nc satisfies 0 < nc ≤ 6. ); Li xd (Al, Ga) yd (Ti, Ge) zd Si ad P md O nd (xd satisfies 1≤xd≤3, yd satisfies 0≤yd≤1, zd satisfies 0≤zd≤2, ad satisfies 0≤ad≤1, md satisfies 1≤md≤7, nd satisfies 3≤nd≤13.) ; Li (3-2xe) M ee xe D ee O(xe) represents a number greater than 0 and less than 0.1, M ee This represents a divalent metal atom. (D) eeRepresents a halogen atom or a combination of two or more halogen atoms; Li xf Si yf O zf (xf satisfies 1 ≤ xf ≤ 5, yf satisfies 0 < yf ≤ 3, zf satisfies 1 ≤ zf ≤ 10.) ; Li xg S yg O zg (xg satisfies 1≤xg≤3, yg satisfies 0<yg≤2, zg satisfies 1≤zg≤10.) ; Li3BO3; Li3BO3-Li2SO4; Li2O-B2O3-P2O5; Li2O-SiO2; Li6BaLa2Ta2O 12 Li3PO (4-3 / 2w) N w (w satisfies w < 1); Li has a LISICON (Lithium super ionic conductor) type crystal structure 3.5 Zn 0.25 GeO4; La with a perovskite-type crystal structure 0.55 Li 0.35 TiO3; LiTi2P3O with a NASICON (Natrium super ionic conductor) crystal structure 12 Li 1+xh+yh (Al, Ga) xh (Ti, Ge) 2-xh Si yh P 3-yh O 12 (xh satisfies 0 ≤ xh ≤ 1, yh satisfies 0 ≤ yh ≤ 1.) ; Li7La3Zr2O with garnet-type crystal structure 12 (LLZ) etc.

[0129] Furthermore, phosphorus compounds containing Li, P, and O are preferred. Examples include lithium phosphate (Li3PO4); LiPON, in which nitrogen element replaces a portion of the oxygen element in lithium phosphate; and LiPOD. 1 (D 1 Preferably, it contains one or more elements selected from Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zr, Nb, Mo, Ru, Ag, Ta, W, Pt, and Au.

[0130] Furthermore, LiA can be preferably used. 1 ON(A 1 It consists of one or more elements selected from Si, B, Ge, Al, C, and Ga.

[0131] (iii) Halogen-based inorganic solid electrolytes

[0132] Halogen-based inorganic solid electrolytes are preferably compounds containing halogen atoms, possessing conductivity of ions belonging to Group 1 or Group 2 of the periodic table, and having electronic insulation properties.

[0133] There are no particular limitations on the type of inorganic solid electrolyte, such as LiCl, LiBr, LiI, and compounds like Li3YBr6 and Li3YCl6 described in ADVANCED MATERIALS, 2018, 30, 1803075. Among these, Li3YBr6 and Li3YCl6 are preferred.

[0134] (iv) Hydride-based inorganic solid electrolytes

[0135] Hydride-based inorganic solid electrolytes are preferably compounds containing hydrogen atoms, possessing ionic conductivity of metals belonging to Group 1 or Group 2 of the periodic table, and having electronic insulation properties.

[0136] There are no particular limitations as hydride-based inorganic solid electrolytes; examples include LiBH4, Li4(BH4)3I, and 3LiBH4-LiCl.

[0137] Inorganic solid electrolytes may contain one or more types.

[0138] There is no particular limitation on the content of inorganic solid electrolyte in the electrode composition. From the viewpoint of dispersibility, ionic conductivity, etc., it is preferable that the total content of the solid component (including the active material) is 50% by mass or more, more preferably 70% by mass or more, and especially preferably 90% by mass or more, out of 100% by mass. As an upper limit, from the same viewpoint, it is preferable that it is 99.9% by mass or less, more preferably 99.5% by mass or less, and especially preferably 99% by mass or less.

[0139] In this invention, solid components refer to those components that, when the electrode composition is dried at 150°C for 6 hours under a nitrogen atmosphere and at a pressure of 1 mmHg, do not evaporate or disappear. Typically, this refers to components other than the dispersion medium described later.

[0140] In the electrode composition, the content ratio of inorganic solid electrolyte to the active material (described later) [content of inorganic solid electrolyte: content of active material] is not particularly limited, considering the median diameter D. 50 The ratio of inorganic solid electrolyte to active substance can be set appropriately. For example, the ratio of inorganic solid electrolyte to active substance can be set to 1:1 to 1:10, preferably 1:1 to 1:6.

[0141] <Active Substances>

[0142] The electrode composition of the present invention may also contain an active material capable of intercalating or deintercalating ions of metals belonging to Group 1 or Group 2 of the periodic table.

[0143] The active material contained in the electrode composition of the present invention is in particulate form, at least in the electrode composition. The shape of the particles is not particularly limited and can be flat, amorphous, etc., but preferably spherical or granular.

[0144] The average particle size (median diameter D) of the active material used in this invention A-50 As long as the median path D is satisfied 50 There are no particular restrictions, and they can be set appropriately. For example, considering factors such as dispersion and conductivity, D... A-50 Preferably, the particle size is 10 μm or less, more preferably 5 μm or less, even more preferably 1 μm or less, and particularly preferably 0.6 μm or less. The lower limit of the average particle size is actually 0.01 μm or more, for example, preferably 0.05 μm or more, more preferably 0.2 μm or more, and even more preferably 0.3 μm or more.

[0145] The average particle size of the active material can be determined in the same way as that of inorganic solid electrolytes.

[0146] The method for adjusting the average particle size can be applied without particular limitation to the known methods described in inorganic solid electrolytes.

[0147] Examples of active materials include positive electrode active materials and negative electrode active materials.

[0148] (Positive electrode active material)

[0149] The positive electrode active material is an active material capable of intercalating and deintercalating ions of metals belonging to Group 1 or Group 2 of the periodic table, preferably an active material capable of reversibly intercalating and deintercalating lithium ions. There are no particular limitations as long as the material has the above-mentioned characteristics, and it can be a transition metal oxide or organic matter from the decomposition battery, or an element that can recombine with Li, such as sulfur.

[0150] Among them, transition metal oxides are preferred as positive electrode active materials, and more preferably materials containing the transition metal element M. a A transition metal oxide (selected from one or more elements including Co, Ni, Fe, Mn, Cu, and V). Furthermore, element M may also be mixed into this transition metal oxide. b (Elements of Group 1(Ia) and Group 2(IIa) of the periodic table, excluding lithium, and elements such as Al, Ga, In, Ge, Sn, Pb, Sb, Bi, Si, P, and B). As a mixing amount, it is preferable to be relative to the transition metal element M. a The amount (100 mol%) is 0-30 mol%. More preferably, it is Li / Ma The mixtures were synthesized by mixing in a molar ratio of 0.3 to 2.2.

[0151] Specific examples of transition metal oxides include (MA) transition metal oxides with a layered rock salt structure, (MB) transition metal oxides with a spinel structure, (MC) lithium-containing transition metal phosphate compounds, (MD) lithium-containing transition metal halophosphate compounds, and (ME) lithium-containing transition metal silicate compounds.

[0152] Specific examples of transition metal oxides (MA) with layered rock salt-type structures include LiCoO2 (lithium cobalt oxide [LCO]), LiNi2O2 (lithium nickel oxide), and LiNi 0.85 Co 0.10 Al 0.05 O2 (lithium nickel cobalt aluminum oxide [NCA]), LiNi 1 / 3 Co 1 / 3 Mn 1 / 3O2 (lithium nickel manganese cobalt oxide [NMC]) and LiNi 0.5 Mn 0.5 O2 (lithium manganese nickel oxide).

[0153] Specific examples of transition metal oxides (MB) with spinel-type structures include LiMn2O4 (LMO), LiCoMnO4, Li2FeMn3O8, Li2CuMn3O8, Li2CrMn3O8, and Li2NiMn3O8.

[0154] Examples of lithium-containing transition metal phosphates (MC) include olivine-type iron phosphates such as LiFePO4 and Li3Fe2(PO4)3, iron pyrophosphates such as LiFeP2O7, cobalt phosphates such as LiCoPO4, and monoclinic NASICON-type vanadium phosphates such as Li3V2(PO4)3 (lithium vanadium phosphate).

[0155] Examples of lithium-containing transition metal halophosphates (MD) include, for example, iron fluorophosphates such as Li2FePO4F, manganese fluorophosphates such as Li2MnPO4F, and cobalt fluorophosphates such as Li2CoPO4F.

[0156] Examples of lithium-containing transition metal silicate compounds include, for example, Li2FeSiO4, Li2MnSiO4, and Li2CoSiO4.

[0157] In this invention, (MA) is preferably a transition metal oxide having a layered rock salt structure, and more preferably LCO or NMC.

[0158] Positive active materials obtained by sintering can also be used after being cleaned with water, acidic aqueous solutions, alkaline aqueous solutions, and organic solvents.

[0159] The electrode composition may contain one or more positive active substances.

[0160] The content of the positive electrode active material in the electrode composition is not particularly limited, but it is preferably 10-97% by mass, more preferably 30-95% by mass, even more preferably 40-93% by mass, and especially preferably 50-90% by mass in 100% by mass of solid components.

[0161] (Negative electrode active material)

[0162] The negative electrode active material is an active material capable of intercalating and deintercalating ions of metals belonging to Group 1 or Group 2 of the periodic table, preferably an active material capable of reversibly intercalating and deintercalating lithium ions. There are no particular limitations on the material as long as it possesses the aforementioned properties; examples include carbonaceous materials, metal oxides, metal composite oxides, lithium monomers, lithium alloys, and negative electrode active materials capable of forming alloys with lithium (capable of alloying). From a reliability perspective, carbonaceous materials, metal composite oxides, or lithium monomers are preferred. From the viewpoint of enabling high-capacity all-solid-state secondary batteries, active materials capable of alloying with lithium are preferred.

[0163] Carbonaceous materials used as negative electrode active materials refer to materials that are essentially composed of carbon. Examples include carbonaceous materials produced by sintering petroleum asphalt, carbon black such as acetylene black (AB), graphite (natural graphite, vapor-grown graphite, and other artificial graphite), and various synthetic resins such as PAN (polyacrylonitrile) resins or furfuryl alcohol resins. Furthermore, examples include various types of carbon fibers such as PAN-based carbon fibers, cellulose-based carbon fibers, pitch-based carbon fibers, vapor-grown carbon fibers, dehydrated PVA (polyvinyl alcohol)-based carbon fibers, lignin carbon fibers, glassy carbon fibers, and activated carbon fibers, as well as mesophase microspheres, graphite whiskers, and planar graphite.

[0164] These carbonaceous materials are classified into non-graphitized carbonaceous materials (also known as hard carbon) and graphite-based carbonaceous materials based on the degree of graphitization. Furthermore, the carbonaceous materials preferably possess the facet spacing or density and crystallite size described in Japanese Patent Application Publication Nos. 62-22066, 2-6856, and 3-45473. The carbonaceous material need not be a single material; mixtures of natural and artificial graphite as described in Japanese Patent Application Publication No. 5-90844, or coated graphite as described in Japanese Patent Application Publication No. 6-4516, etc., can also be used.

[0165] As a carbonaceous material, hard carbon or graphite is preferred, with graphite being more preferred.

[0166] As oxides of metals or half-metals suitable as negative electrode active materials, there are no particular limitations as long as they are oxides capable of absorbing and releasing lithium. Examples include oxides of metal elements (metal oxides), composite oxides of metal elements, or composite oxides of metal elements and half-metal elements (collectively referred to as metal composite oxides), and oxides of half-metal elements (half-metal oxides). Among these oxides, amorphous oxides are preferred, and further preferred are chalcogenides, products of the reaction between metal elements and elements of Group 16 of the periodic table. In this invention, a half-metal element refers to an element exhibiting intermediate properties between a metal element and a non-half-metal element, typically including six elements: boron, silicon, germanium, arsenic, antimony, and tellurium, and further including three elements: selenium, polonium, and astatine. Furthermore, amorphous refers to a material having a broad scattering band with vertices in the region of 20° to 40° at 2θ values ​​using CuKα X-ray diffraction, and may also have crystalline diffraction lines. The strongest intensity of the crystalline diffraction lines appearing in the region of 40° to 70° at a 2θ value is preferably 100 times or less than the intensity of the diffraction line at the apex of the broad scattering band appearing in the region of 20° to 40° at a 2θ value, more preferably 5 times or less, and especially preferably a non-crystalline diffraction line.

[0167] Among the compounds comprising the aforementioned amorphous oxides and chalcogenides, amorphous oxides of half-metallic elements or the aforementioned chalcogenides are more preferred, and (composite) oxides or chalcogenides comprising one or more elements selected from groups 13(IIIB) to 15(VB) of the periodic table (e.g., Al, Ga, Si, Sn, Ge, Pb, Sb, and Bi) are particularly preferred. Specific examples of preferred amorphous oxides and chalcogenides include, for example, Ga₂O₃, GeO, PbO, PbO₂, Pb₂O₃, Pb₂O₄, Pb₃O₄, Sb₂O₄, Sb₂O₈Bi₂O₃, Sb₂O₈Si₂O₃, Sb₂O₅, Bi₂O₃, Bi₂O₄, GeS, PbS, PbS₂, Sb₂S₃, or Sb₂S₅.

[0168] As a negative electrode active material that can be used with amorphous oxides centered on Sn, Si, and Ge, carbonaceous materials, lithium monomers, lithium alloys, and negative electrode active materials that can be alloyed with lithium are preferred examples.

[0169] From the viewpoint of high current density charge and discharge characteristics, oxides of metal or half-metal elements, especially metal (composite) oxides and the aforementioned chalcogenides, preferably contain at least one of titanium and lithium as constituent components. Examples of lithium-containing metal composite oxides (lithium composite metal oxides) include composite oxides of lithium oxide with the aforementioned metal (composite) oxides or chalcogenides; more specifically, Li₂SnO₂ can be cited.

[0170] The negative electrode active material, such as a metal oxide, preferably contains titanium (titanium oxide). Specifically, due to Li4Ti5O 12 Lithium titanate (LTO) exhibits minimal volume change during lithium ion adsorption and deintercalation, resulting in excellent rapid charge and discharge characteristics. It is preferred in terms of both suppressing electrode degradation and improving the lifespan of lithium-ion secondary batteries.

[0171] There are no particular restrictions on the lithium alloy used as the negative electrode active material, as long as it is an alloy commonly used as the negative electrode active material in secondary batteries. For example, lithium-aluminum alloys can be cited. Specifically, lithium-aluminum alloys can be cited, which are made by adding 10% by mass of aluminum to lithium as the base metal.

[0172] There are no particular limitations on the negative electrode active material that can form an alloy with lithium, as long as it is a negative electrode active material commonly used in secondary batteries. Examples of such active materials include (negative electrode) active materials (alloys, etc.) containing silicon or tin, metals such as Al and In, and preferably negative electrode active materials containing silicon (silicon-containing active materials) that can achieve higher battery capacity. More preferably, active materials containing silicon have a silicon content of 50 mol% or more of all constituent elements.

[0173] Generally, negative electrodes containing these active materials (e.g., Si negative electrodes containing silicon-containing active materials, Sn negative electrodes containing tin-containing active materials, etc.) can absorb more Li ions compared to carbon negative electrodes (graphite and acetylene black, etc.). That is, the amount of Li ions retained per unit mass increases. Therefore, the battery capacity (energy density) can be increased. Consequently, it has the advantage of extending battery operating time.

[0174] Examples of silicon-containing active materials include silicon materials such as Si and SiOx (0 < x ≤ 1), as well as silicon-containing alloys (e.g., LaSi2, VSi2, La-Si, Gd-Si, Ni-Si) or structured active materials (e.g., LaSi2 / Si) containing elements such as titanium, vanadium, chromium, manganese, nickel, copper, and lanthanum. Additionally, active materials containing silicon elements such as SnSiO3 and SnSiS3, and tin elements, are also included. Furthermore, SiOx can be used as a negative electrode active material (a half-metal oxide) itself, and since Si is generated through the operation of an all-solid-state secondary battery, it can be used as a negative electrode active material (its precursor material) that can be alloyed with lithium.

[0175] Examples of anode active materials containing tin include those containing Sn, SnO, SnO2, SnS, SnS2, and the aforementioned silicon and tin elements. Furthermore, composite oxides with lithium oxide, such as Li2SnO2, can also be cited.

[0176] In this invention, the above-mentioned negative electrode active material can be used without particular limitation. However, from the viewpoint of battery capacity, it is preferable to use a negative electrode active material that can be alloyed with lithium. More preferably, it is the above-mentioned silicon material or silicon-containing alloy (an alloy containing silicon element). It is even more preferably to contain silicon (Si) or a silicon-containing alloy.

[0177] The electrode composition may contain one or more negative electrode active substances.

[0178] The content of the negative electrode active material in the electrode composition is not particularly limited, but is preferably 10-90% by mass, more preferably 20-85% by mass, more preferably 30-80% by mass, and even more preferably 40-75% by mass in 100% by mass of solid components.

[0179] As a determination method, inductively coupled plasma (ICP) emission spectroscopy can be used. As a simple method, the chemical formula of the compound obtained by the above-mentioned firing method can be calculated from the mass difference of the powder before and after firing.

[0180] (Coating of active substances)

[0181] The surfaces of both the positive and negative electrode active materials can be coated with different metal oxides. Examples of surface coating agents include metal oxides containing Ti, Nb, Ta, W, Zr, Al, Si, or Li. Specifically, examples include spinel titanate, tantalum oxides, niobium oxides, and lithium niobate compounds; for instance, Li₄Ti₅O₅ can be used. 12, Li2Ti2O5, LiTaO3, LiNbO3, LiAlO2, Li2ZrO3, Li2WO4, Li2TiO3, Li2B4O7, Li3PO4, Li2MoO4, Li3BO3, LiBO2, Li2CO3, Li2SiO3, SiO2, TiO2, ZrO2, Al2O3, B2O3, etc.

[0182] Furthermore, the electrode surface containing positive or negative active materials can be surface-treated with sulfur or phosphorus.

[0183] Furthermore, the particle surface of the positive or negative active material can be surface-treated by photochemical rays or active gas (plasma, etc.) before and after the aforementioned surface coating.

[0184] <Polymer Adhesives>

[0185] The electrode composition of the present invention contains a polymer binder that is composed of linear polymers. If the polymer binder is composed of linear polymers, it enhances the effect of the aforementioned radius of rotation α and median diameter D. 50 The effect of the satisfied relationship is to suppress liquid dripping and uneven coating of the electrode composition and improve ionic conductivity.

[0186] In this invention, a linear polymer refers to a polymer having a main chain formed by the straight-chain polymerization or condensation of condensation compounds, and without branched polymeric chains (including grafted chains) or cross-linked structures. Examples include chain polymers of polymeric compounds having a single carbon-carbon double bond, and stepwise polymers of difunctional condensation compounds.

[0187] In this invention, the polymer backbone refers to all linear molecular chains that constitute the polymer and can be considered branches or side groups relative to the backbone. While depending on the mass-average molecular weight of the branched chains considered as branches or side groups, typically the longest chain in the polymer's molecular chains becomes the backbone. However, terminal groups present at the ends of the polymer are not included in the backbone. Furthermore, polymer side chains refer to branched chains other than the backbone, including both short and long chains.

[0188] -Physical properties or characteristics of linear polymers or polymer adhesives-

[0189] Linear polymers preferably satisfy the following SP values, and polymer adhesives preferably indicate the following adsorption rates and solubility in the dispersion medium. Furthermore, in addition to these properties, polymer adhesives or linear polymers preferably also suitably possess the following properties.

[0190] The SP value, which is a preferred property for linear polymers, is not particularly limited, and can be set to, for example, 12.0 to 21.5 MPa. 1 / 2 However, from the viewpoint of the dispersibility of the electrode composition, a pressure of 12.0 to 21.5 MPa is preferred. 1 / 2 More preferably 16-20 MPa 1 / 2 More preferably 17-20 MPa 1 / 2 Especially preferred is 17–19.5 MPa 1 / 2 The optimal value is 18–19.5 MPa. 1 / 2 .

[0191] The calculation method for SP values ​​is explained.

[0192] First, unless otherwise specified, the SP value (MPa) of each component (structural unit) constituting the linear polymer is determined by the Hoy method. 1 / 2 (Refer to H.H. L. JOURNAL OF PAINT TECHNOLOGY Vol. 42, No. 541, 1970, 76-118 and POLYMER HANDBOOK 4) th Chapter 59, VII, page 686 (Tables 5 and 6 and the formulas in Table 6).

[0193] [Formula 2]

[0194]

[0195] In the formula, δ t This represents the SP value. Ft represents the molar attraction function (J×cm). 3 ) 1 / 2 / mol, expressed by the following formula. V represents the molar volume (cm³). 3 / mol), represented by the following formula.

[0196] It is represented by the following formula.

[0197] F t =∑n i F t，i V=∑n i V i

[0198]

[0199] In the above formula, F t，i V represents the molar attraction function of each structural unit. i Representing the molar volume of each structural unit

[0200] Product, Δ(P) T，i This represents the correction value for each structural unit, and ni represents the number of each structural unit.

[0201] Using the SP values ​​(MPa) of the constituent components determined above. 1 / 2 The SP of linear polymers can be calculated using the following formula. p Value (MPa) 1 / 2 In addition, the SP values ​​of the constituent components obtained from the above literature will be converted into SP values ​​(MPa). 1 / 2 (For example, 1cal) 1 / 2 cm -3 / 2 ≈2.05J 1 / 2 cm -3 / 2 ≈2.05MPa 1 / 2 And use it.

[0202] Sp p 2 =(SP1) 2 ×W1)+(SP2 2 ×W2)+……

[0203] In the formula, SP1, SP2, ... represent the SP values ​​of the constituent components, and W1, W2, ... represent the mass fractions of the constituent components. In this invention, the mass fraction of the constituent component is the mass fraction of the linear polymer of the constituent component (the raw material compound into which the constituent component is introduced).

[0204] The SP value of a polymer can be adjusted according to the type or composition of the linear polymer (the type and content of the constituent components).

[0205] From the viewpoint of achieving a higher degree of dispersibility, it is preferable that the SP value of the linear polymer is the difference (absolute value) of the SP value relative to the SP value of the dispersion medium within the range described below.

[0206] The preferred characteristic of a polymer binder is the adsorption rate, which is the adsorption rate (A) of the active material contained in the electrode composition by the dispersion medium within the electrode composition. AM There are no particular limitations, but it is preferably below 40%. If the adsorption rate A of the active substance... AM If the concentration is below 40%, it will not be over-adsorbed onto active substances, which helps improve dispersibility and conductivity.

[0207] In this invention, the adsorption rate A of the polymer adhesive is... AMThis value is measured using the active material and dispersion medium contained in the electrode composition, and it is an indicator of the degree to which the polymer binder in the dispersion medium is adsorbed onto the active material. Here, the adsorption of the active material by the polymer binder includes not only physical adsorption but also chemical adsorption (adsorption through the formation of chemical bonds, adsorption through electron donation and acceptance, etc.).

[0208] When the electrode composition contains multiple active substances, the adsorption rate is set to the active substances having the same composition (type and content) as those in the electrode composition. Similarly, when the electrode composition contains multiple dispersion media, the adsorption rate is also measured using dispersion media having the same composition (type and content) as those in the electrode composition. Furthermore, when multiple polymer binders are used, the adsorption rate is set to the multiple polymer binders, similar to the electrode composition.

[0209] In this invention, the adsorption rate of the polymer adhesive is set as a value calculated by the method described in the examples.

[0210] In this invention, the adsorption rate A of the active substance AM The parameters can be appropriately set by the type of polymer contained in the polymer adhesive (the structure and composition of the polymer chain), the type or content of the functional groups of the polymer, and the method of polymer adhesive (the amount dissolved in the dispersion medium).

[0211] From the perspective of further improving dispersibility, the adsorption rate A AM It can be set to 60% or less, preferably 45% or less, and more preferably 30% or less. On the other hand, the adsorption rate A AM There is no particular limitation on the lower limit, and it can be set to 0%. From the point of view of dispersibility, the lower limit of adsorption rate is preferably small, for example, preferably 0.1% or more, and more preferably 1% or more.

[0212] A preferred characteristic of the polymer binder (linear polymer) is its solubility relative to the dispersion medium contained in the electrode composition. While the amount of polymer binder in the electrode composition depends on its content, it is generally present in the electrode composition dissolved in the dispersion medium. Thus, the polymer binder stably functions to disperse solid particles in the dispersion medium.

[0213] In this invention, the way in which the polymer binder dissolves in the dispersion medium in the electrode composition is not limited to all ways in which the polymer binder dissolves in the dispersion medium. For example, if the solubility in the dispersion medium is 80% or more, a portion of the polymer binder may be insoluble in the electrode composition.

[0214] The method for determining solubility is as follows: A specified amount of the polymer binder to be tested is weighed into a glass bottle, and 100 g of a dispersion medium of the same type as the dispersion medium contained in the electrode composition is added. The mixture is stirred at 80 rpm for 24 hours at 25°C on a mixing rotor. The transmittance of the mixture obtained after 24 hours of stirring is determined under the following conditions: This test (transmittance determination) is performed by varying the amount of binder dissolved (the specified amount mentioned above), and the upper limit concentration X (mass%) at which the transmittance becomes 99.8% is defined as the solubility of the polymer binder in the dispersion medium.

[0215] <Transmittance Measurement Conditions>

[0216] Dynamic light scattering (DLS) measurement

[0217] Apparatus: DLS-8000 DLS measuring device manufactured by Otsuka Electronics Co., Ltd.

[0218] Laser wavelength and output: 488nm / 100mW

[0219] Sample cell: NMR tube

[0220] The linear polymer only needs to have a radius of gyration α within the aforementioned range; its mass-average molecular weight is not particularly limited and can be appropriately set considering the aforementioned radius of gyration α. ​​The mass-average molecular weight of the linear polymer can be, for example, set to 10,000 or more, preferably 15,000 or more, more preferably 30,000 or more, and even more preferably 50,000 or more. As an upper limit, it is practically 5,000,000 or less, preferably 4,000,000 or less, more preferably 3,000,000 or less, even more preferably 2,000,000 or less, and particularly preferably 500,000 or less.

[0221] The mass-average molecular weight of the fluoropolymers described later can also be set within the above-mentioned range, but considering the radius of gyration α, it is further preferred to be 150,000 or more, particularly preferred to be 200,000 or more, and most preferably 300,000 or more. As an upper limit, it is further preferred to be 1,500,000 or less, and particularly preferred to be 1,200,000 or less.

[0222] -Determination of molecular weight-

[0223] In this invention, the molecular weight of polymers, polymer chains, and macromonomers, unless otherwise specified, refers to the mass-average molecular weight or number-average molecular weight converted from standard polystyrene obtained by gel permeation chromatography (GPC). As a method for determination, methods under condition 1 or condition 2 (preferred) can be generally cited. Appropriate eluents are selected and used according to the type of polymer or macromonomer.

[0224] (Condition 1)

[0225] Column: Connects 2 TOSOH TSKgel Super AWM-H (trade name, manufactured by TOSOH CORPORATION)

[0226] Charge carriers: 10 mM LiBr / N-methylpyrrolidone

[0227] Measurement temperature: 40℃

[0228] Carrier flow rate: 1.0 ml / min

[0229] Sample concentration: 0.1% by mass

[0230] Detector: RI (Refractive Index) Detector

[0231] (Condition 2)

[0232] Tubes: Tubes connected to TOSOH TSKgel Super HZM-H, TOSOH TSKgel Super HZ4000, and TOSOH TSKgel Super HZ2000 (all trade names, manufactured by Tosoh Corporation) are used.

[0233] Charge carrier: tetrahydrofuran

[0234] Measurement temperature: 40℃

[0235] Carrier flow rate: 1.0 ml / min

[0236] Sample concentration: 0.1% by mass

[0237] Detector: RI (Refractive Index) Detector

[0238] The moisture concentration of the polymer binder (linear polymer) is preferably below 100 ppm (by mass). Furthermore, this polymer binder can be used to crystallize and dry the polymer, or a dispersion of the polymer binder can be used directly.

[0239] The linear polymer is preferably amorphous. In this invention, "amorphous" polymer typically means that no endothermic peak due to crystal melting is observed when measured at the glass transition temperature.

[0240] -Straight-chain polymer-

[0241] As long as the linear polymers meet the above-mentioned preferred characteristics or physical properties, there are no particular restrictions on their type and composition, and various polymers that can be used as adhesives for all-solid-state secondary batteries can be used.

[0242] The linear polymer preferably contains a component having a functional group with a pKa of 8 or less. If the linear polymer contains this component, the radius of rotation α can be set within an appropriate range, and the coating properties and ionic conductivity of the electrode composition can be further improved by using a polymer binder.

[0243] This constituent component has functional groups with a pKa of 8 or less, either directly or via a linker, in the partial structure of the main chain of the linear polymer. The partial structure incorporated into the main chain of the linear polymer can be appropriately selected depending on the type of linear polymer, for example, a carbon chain (carbon-carbon bond).

[0244] pKa is the negative common logarithm (-logKa) of the acid dissociation constant (Ka) in water at 25°C. pKa can be calculated by adding 0.01 mol / L sodium hydroxide solution dropwise to an aqueous solution of the polymer binder and reading the amount of sodium hydroxide solution added to the half-equivalent point. There are no particular restrictions on functional groups with a pKa of 8 or less; examples include acidic functional groups such as carboxyl, phosphoryl (phosphate), phosphonic acid, and sulfonyl (sulfonic acid) groups, as well as phenolic hydroxyl groups.

[0245] There are no particular limitations on the linking group; examples include alkylene groups (preferably 1 to 12 carbon atoms, more preferably 1 to 6, and even more preferably 1 to 3), alkenyl groups (preferably 2 to 6 carbon atoms, more preferably 2 to 3), aryl groups (preferably 6 to 24 carbon atoms, more preferably 6 to 10), oxygen atoms, sulfur atoms, and imino groups (-NR). N -:R N This refers to groups representing hydrogen atoms, alkyl groups with 1 to 6 carbon atoms, or aryl groups with 6 to 10 carbon atoms, carbonyl groups, phosphate linkages (-OP(OH)(O)-O-), phosphonic acid linkages (-P(OH)(O)-O-), or combinations thereof. Preferably, the linkage group is a group composed of alkylene, arylene, carbonyl, oxygen, sulfur, and imino groups; more preferably, it is a group composed of alkylene, arylene, carbonyl, oxygen, imino, or polyalkoxy chains (combinations of alkylene and oxygen atoms); and even more preferably, it contains a -CO-O- group or a -CO-N(R) group. N)-base(R N A group representing a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 10 carbon atoms, or an aryl group. As a group containing -CO-O- or -CO-N(R) N The linking group can include, but is not limited to, groups such as alkylene, arylene, -CO-O-, and polyalkoxide chains. The number of atoms constituting the linking group and the number of linking atoms are as described below. However, the polyalkoxide chains constituting the linking group are not limited to those described above.

[0246] In this invention, the number of atoms constituting the linking group is preferably 1 to 36, more preferably 1 to 24, and even more preferably 1 to 12. The number of connecting atoms in the linking group is preferably 10 or less, more preferably 8 or less. A lower limit is 1 or more. The above-mentioned number of connecting atoms refers to the minimum number of atoms connecting the defined structural parts. For example, in the case of -CH2-C(=O)-O-, the number of atoms constituting the linking group is 6, but the number of connecting atoms is 3.

[0247] The portion of the structure incorporated into the main chain and the linking group may each have substituents. There are no particular limitations on such substituents; for example, groups selected from substituent Z described later can be cited.

[0248] As a constituent having a functional group of pKa 8 or less, it can be appropriately combined and incorporated into the main chain structure, the functional group of pKa 8 or less, and the linking group. For example, constituents derived from (meth)acrylic acid compounds (described later), constituents derived from compounds in which a functional group of pKa 8 or less is introduced into (meth)acrylic acid compound (M1), and constituents derived from compounds in which a functional group of pKa 8 or less is introduced into vinyl compound (M2) (described later) are preferred. Examples include (meth)acrylic acid compounds, acrylate compounds with functional groups of pKa 8 or less, and vinyl compounds (M2) with functional groups of pKa 8 or less (especially styrene compounds with functional groups of pKa 8 or less, and open-ring forms (including monoesters) of unsaturated carboxylic anhydrides (e.g., maleic anhydride compounds). When the open-ring form of the unsaturated carboxylic anhydride is a monoester, the group forming the ester is not particularly limited, and groups selected from substituent Z (described later) are preferred.

[0249] Specific examples of constituent components having functional groups below pKa8 can be given as examples of constituent components in the linear polymers described below, but the present invention is not limited to these.

[0250] Linear polymers can have one or more functional groups with pKa below 8. The content of functional groups with pKa below 8 in linear polymers is appropriately determined by taking into account the rotation radius α and SP value of the linear polymer, etc., which will be described in detail later.

[0251] As a linear polymer, polymers having polymer chains having at least one bond selected from urethane bonds, urea bonds, amide bonds, imide bonds and ester bonds or carbon-carbon double bonds on the main chain are preferred examples.

[0252] The aforementioned bonds are not particularly limited as long as they are included in the polymer backbone; they can be any form contained in the constituent components (repeating units) and / or contained as bonds connecting different constituent components to each other. Furthermore, the backbone is not limited to one type of bond; it can contain two or more types, preferably one to six, and more preferably one to four. In this case, the bonding method of the backbone is not particularly limited; it can randomly contain two or more types of bonds, or it can be a partitioned backbone with partitions containing specific bonds and partitions containing other bonds.

[0253] There are no particular limitations on the main chain having the above-mentioned bonds, but it is preferred to have a main chain having at least one partition of the above-mentioned bonds, and more preferably a main chain made of polyamide, polyurea or polyurethane.

[0254] Polymers that have urethane bonds, urea bonds, amide bonds, imide bonds, or ester bonds in their main chain, as mentioned above, include, for example, step-growth polymers (condensation, addition, or addition condensation) such as polyurethane, polyurea, polyamide, polyimide, and polyester, or copolymers thereof. The copolymer can be a block copolymer in which the aforementioned polymers are used as chain segments, or a random copolymer formed by the random bonding of the constituent components of two or more of the aforementioned polymers.

[0255] Examples of chain polymers with carbon-carbon double bonds in their main chain include fluoropolymers, hydrocarbon polymers, ethylene polymers, and (meth)acrylic acid polymers. The polymerization method for these chain polymers is not particularly limited; they can be any of block copolymers, alternating copolymers, or random copolymers, with random copolymers being preferred.

[0256] As a linear polymer, the above-mentioned polymers can be appropriately selected, preferably (meth)acrylic polymers, fluoropolymers or vinyl polymers, more preferably (meth)acrylic polymers or fluoropolymers.

[0257] Regarding (meth)acrylic acid polymers preferred as linear polymers, examples include (meth)acrylic acid compound (M1), preferably a (co)polymer of a compound having a functional group having a functional group of pKa 8 or less, and a polymer consisting of a polymer containing 50% by mass or more of a functional group derived from (meth)acrylic acid compound. Here, when the functional group having a functional group of pKa 8 or less is a (meth)acrylic acid compound or a component derived from (meth)acrylic acid compound, the content of the functional group having a functional group of pKa 8 or less is included in the content of the component derived from (meth)acrylic acid compound. Furthermore, copolymers with vinyl monomers other than (meth)acrylic acid compound (M1) are also preferred as (meth)acrylic acid polymers.

[0258] Preferred fluorinated polymers as linear polymers include (co)polymers of polymeric compounds containing fluorine atoms (fluorinated polymeric compounds). Also preferred as fluorinated polymers are copolymers of (meth)acrylic acid compound (M1), vinyl monomers other than (meth)acrylic acid compound (M1), and compounds incorporating functional groups having a pKa of 8 or less.

[0259] Regarding vinyl polymers preferred as linear polymers, examples include vinyl monomers other than (meth)acrylic acid compound (M1), preferably copolymers of compounds with functional groups having a further pKa of 8 or less, and polymers composed of copolymers containing 50% by mass or more of the functional group derived from vinyl monomers. Here, when the functional group with a pKa of 8 or less is derived from vinyl monomers, the content of the functional group with a pKa of 8 or less is included in the content of the component derived from vinyl monomers. Furthermore, copolymers with (meth)acrylic acid compound (M1) are also preferred as vinyl polymers.

[0260] Examples of (meth)acrylic acid compounds (M1) include compounds other than those containing a functional group having a pKa of 8 or less, such as (meth)acrylate compounds, (meth)acrylamide compounds, and (meth)acrylonitrile compounds. Among these, (meth)acrylate compounds and (meth)acrylamide compounds are preferred.

[0261] Examples of (meth)acrylate compounds include alkyl (meth)acrylate compounds, aryl (meth)acrylate compounds, heterocyclic (meth)acrylate compounds, and polymeric (meth)acrylate compounds, with alkyl (meth)acrylate compounds being preferred. The number of carbon atoms in the alkyl group constituting the (meth)acrylate compound is not particularly limited, and can be, for example, 1 to 24. From the viewpoint of improving dispersibility and adhesion, 3 to 20 is preferred, more preferably 4 to 16, and even more preferably 6 to 14. In this invention, the alkyl (meth)acrylate compound can also be used in combination with a (meth)acrylate compound having a long-chain alkyl group with 4 to 16 carbon atoms and a (meth)acrylate compound having a short-chain alkyl group with 1 to 3 carbon atoms. The number of carbon atoms in the aryl group constituting the aryl ester is not particularly limited, and can be, for example, 6 to 24, preferably 6 to 10, and more preferably 6. In the (meth)acrylamide compound, the nitrogen atom of the amide group can be substituted with an alkyl or aryl group. The polymer chains of (meth)acrylate compounds are not particularly limited, but are preferably alkylene oxide polymer chains, more preferably polymer chains composed of alkylene oxides having 2 to 4 carbon atoms. The degree of polymerization of the polymer chains is not particularly limited and can be appropriately set. The ends of the polymer chains are typically bonded with alkyl or aryl groups.

[0262] There are no particular limitations on the fluorinated polymerizable compounds, and examples include compounds commonly used in fluorinated polymers. For example, this refers to compounds in which fluorine atoms are directly or via a linker group bonded to a carbon-carbon double bond. There are no particular limitations on the linker group, and examples include linkers in constituent components having functional groups with a pKa of 8 or less. There are no particular limitations on the fluorinated polymerizable compounds, and examples include fluorinated vinylidene fluoride (VDF), hexafluoropropylene (HFP), tetrafluoroethylene (TFE), trifluoroethylene, monofluoroethylene, trifluorochloroethylene, and perfluoroalkyl ethers such as trifluoromethyl vinyl ether and pentafluoroethyl vinyl ether.

[0263] There are no particular limitations on the vinyl monomers used, but vinyl compounds other than those containing functional groups with pKa 8 or lower, which are capable of copolymerizing with vinyl compounds such as (meth)acrylic acid compounds (M1), are preferred. Examples include aromatic vinyl compounds such as styrene compounds, vinylnaphthalene compounds, and vinyl carbazole compounds, as well as compounds that do not contain functional groups with pKa 8 or lower, such as allyl compounds, vinyl ether compounds, vinyl ester compounds, itaconic acid dialkyl ester compounds, and unsaturated carboxylic anhydrides. Examples of vinyl compounds include "vinyl monomers" as described in Japanese Patent Application Publication No. 2015-88486.

[0264] (Meth)acrylic acid compounds (M1), fluorinated polymeric compounds, and vinyl compounds (M2) may each have substituents. There are no particular restrictions on the substituents, as long as they are functional groups other than those with a pKa of 8 or less, and groups selected from substituents Z described later can be given as examples.

[0265] As (meth)acrylic acid compound (M1) and vinyl compound (M2), compounds represented by the following formula (b-1) are preferred. This compound is preferably different from the compounds described above that incorporate functional groups having a pKa of 8 or less.

[0266] [Chemical Formula 1]

[0267]

[0268] In the formula, R 1 The group represents a hydrogen atom, hydroxyl group, cyano group, halogen atom, alkyl group (preferably with 1 to 24 carbon atoms, more preferably 1 to 12, especially preferably 1 to 6), alkenyl group (preferably with 2 to 24 carbon atoms, more preferably 2 to 12, especially preferably 2 to 6), alkynyl group (preferably with 2 to 24 carbon atoms, more preferably 2 to 12, especially preferably 2 to 6), or aryl group (preferably with 6 to 22 carbon atoms, more preferably 6 to 14). Among these, hydrogen atoms or alkyl groups are preferred, and hydrogen atoms or methyl groups are even more preferred.

[0269] R 2 Represents a hydrogen atom or substituent. It can be represented as R. 2 The substituents are not particularly limited, and examples include alkyl (which may be branched, but preferably straight), alkenyl (preferably with 2 to 12 carbon atoms, more preferably 2 to 6, especially preferably 2 or 3), aryl (preferably with 6 to 22 carbon atoms, more preferably 6 to 14), aralkyl (preferably with 7 to 23 carbon atoms, more preferably 7 to 15), and cyano.

[0270] The number of carbon atoms in the alkyl group has the same meaning as the number of carbon atoms in the alkyl group constituting the above-mentioned (meth)acrylate alkyl ester compound, and the preferred range is also the same.

[0271] L 1 The linker is not particularly limited and can be any of the aforementioned constituents having functional groups with pKa 8 or less.

[0272] When L 1 Use -CO-O- or -CO-N(R) N )-base(R N As described above. (where -O- or -N(R)) N )- and R 2 (By bonding method), the compound represented by the above formula (b-1) is equivalent to (meth)acrylic acid compound (M1), and otherwise is equivalent to vinyl compound (M2).

[0273] n is 0 or 1, preferably 1. Where, -(L 1 ) n -R 2 In the case of a substituent (e.g., alkyl), set n to 0 and R to 0. 2 Set as a substituent (alkyl).

[0274] As the aforementioned (meth)acrylic acid compound (M1), compounds represented by the following formulas (b-2) or (b-3) are also preferred. These compounds are preferably different from the aforementioned compounds that incorporate functional groups having a pKa of 8 or less.

[0275] [Chemical Formula 2]

[0276]

[0277] R 1 The meanings of and n are the same as those in the above formula (b-1).

[0278] R 3 With R 2 The meanings are the same.

[0279] L 2 As a connecting base, its meaning is the same as that of L mentioned above. 1 The meanings are the same.

[0280] L 3 As a connecting base, its meaning is the same as that of L mentioned above. 1 The meaning is the same, and preferably an alkylene group with 1 to 6 carbon atoms (preferably 2 to 4).

[0281] m is preferably an integer from 1 to 200, more preferably an integer from 1 to 100, and even more preferably an integer from 1 to 50.

[0282] In the above formulas (b-1) to (b-3), the carbon atoms that form polymeric groups and are not bonded to R 1 The carbon atom is represented as an unsubstituted carbon atom (H₂C=), but it can have substituents. There are no particular restrictions on the substituents, but for example, R can be used. 1 The above-mentioned groups.

[0283] Furthermore, in formulas (b-1) to (b-3), groups employing substituents such as alkyl, aryl, alkylene, and arylene may have substituents to a extent that does not impair the effects of the present invention. There are no particular limitations on the substituents; for example, groups selected from substituent Z described later can be cited, specifically, halogen atoms, etc.

[0284] As specific examples of (meth)acrylic acid compound (M1) and vinyl compound (M2), compounds that are derived constituents in the linear polymers described later can be cited, but the present invention is not limited to these.

[0285] The linear polymer may contain one or more of the above-mentioned (meth)acrylic acid compounds (M1), fluorinated polymeric compounds, or vinyl monomers.

[0286] The linear polymer can also take the form of having or not having components derived from macromonomers with a number average molecular weight of 1,000 or more. In this invention, the form of not having components derived from macromonomers is preferred. As for macromonomers with a number average molecular weight of 1,000 or more, there are no particular limitations as long as they do not contain compounds represented by any of the formulas (b-1) to (b-3) above. For example, the macromonomer (X) described in Japanese Patent Application Publication No. 2015-088486 can be cited.

[0287] The content of each component in a linear polymer is not particularly limited and can be determined by considering factors such as the polymer's radius of rotation α and SP value, for example, within the following range.

[0288] The content of each component in the (meth)acrylic acid polymer is set within the range below, for example, so that the total content of all components is 100 by mass.

[0289] The content of the constituent components derived from (meth)acrylic acid compounds (constituent components having functional groups of pKa 8 or less, including those derived from (meth)acrylic acid compounds and those derived from (meth)acrylic acid compounds (M1)) is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 90% by mass or more. The upper limit of the content can also be set to 100% by mass, but it can also be set to 98% by mass or less.

[0290] The content of the constituent components derived from (meth)acrylic acid compound (M1) (excluding constituent components having functional groups with pKa below 8) is preferably 45 to 100% by mass, more preferably 50 to 100% by mass, even more preferably 70 to 100% by mass, and particularly preferably 90 to 98% by mass.

[0291] The content of the constituent components having functional groups with pKa 8 or less is preferably 0 to 55% by mass, more preferably 1 to 30% by mass, even more preferably 3 to 20% by mass, and especially preferably 3 to 7% by mass.

[0292] The content of the constituent components derived from vinyl compounds (excluding constituent components having functional groups with a pKa of 8 or less) is set to 50% by mass or less, preferably 0 to 40% by mass, more preferably 0 to 30% by mass. The content of the constituent components derived from styrene compounds in the vinyl compounds is set with consideration of the above range, preferably 0 to 40% by mass, more preferably 10 to 30% by mass.

[0293] The content of components derived from macromolecular monomers is, for example, preferably 0 to 30% by mass.

[0294] The content of each component in the fluoropolymer is set within the range below, for example, so that the total content of all components is 100 by mass.

[0295] The content of the constituent components derived from fluorinated polymeric compounds (constituent components having functional groups below pKa8, including those derived from fluorinated polymeric compounds and those derived from fluorinated polymeric compounds without functional groups below pKa8) is not particularly limited, but is more preferably 60% by mass or more, and even more preferably 80% by mass or more. The upper limit of the content can also be set to 100% by mass, preferably 97% by mass or less, and more preferably 94% by mass or less.

[0296] The content of the constituent components derived from fluorinated polymeric compounds (excluding constituent components having functional groups with a pKa of 8 or less) is preferably 50 to 100% by mass, more preferably 60 to 100% by mass, and even more preferably 70 to 100% by mass. The content of the constituent components derived from vinylidene fluoride compounds in the fluorinated polymeric compounds is set within the above range, preferably 50 to 90% by mass, more preferably 60 to 85% by mass. Furthermore, the content of the constituent components derived from hexafluoropropylene compounds is set within the above range, preferably 10 to 50% by mass, more preferably 15 to 40% by mass.

[0297] The content of the constituent components having functional groups with pKa 8 or less is preferably 0 to 30% by mass, more preferably 0 to 20% by mass, and even more preferably 0.05 to 10% by mass.

[0298] There are no particular restrictions on the content of components derived from (meth)acrylic acid compound (M1), components derived from vinyl compounds, or components derived from macromolecular monomers; for example, they can be set to 0 to 15 by mass.

[0299] The content of each component in the vinyl polymer is set within the range below, for example, so that the total content of all components is 100 by mass.

[0300] The content of the constituent components derived from vinyl monomers (constituent components having functional groups below pKa 8 and constituent components derived from vinyl monomers other than (meth)acrylic acid compound (M1)) is preferably more than 50% by mass, more preferably 60% by mass or more, and even more preferably 70% by mass or more. The upper limit of the content can also be set to 100% by mass, but it can also be set to 90% by mass or less.

[0301] The content of the constituent components derived from vinyl compounds (excluding constituent components having functional groups below pKa 8) is preferably 50 to 90% by mass, more preferably 60 to 90% by mass, and even more preferably 65 to 85% by mass. The content of the constituent components derived from styrene compounds in the vinyl compounds is set with consideration of the above range, preferably 0 to 80% by mass, and more preferably 10 to 50% by mass.

[0302] The content of the constituent components having functional groups with pKa 8 or less is preferably 0 to 30% by mass, more preferably 0 to 20% by mass, and even more preferably 0.05 to 10% by mass.

[0303] The content of the constituent components derived from (meth)acrylic acid compound (M1) (excluding constituent components having functional groups below pKa 8) is less than 50% by mass, preferably 0 to 40% by mass, more preferably 0 to 30% by mass.

[0304] The content of components derived from macromolecular monomers is, for example, preferably 0 to 30% by mass.

[0305] Linear polymers may have substituents. There are no particular limitations on the substituents, but groups selected from substituent Z below are preferred.

[0306] Linear polymers can be synthesized by selecting raw material compounds based on the types of bonds in the main chain and by using known methods, and by performing polymerization or condensation polymerization on the raw material compounds.

[0307] -Substituent Z-

[0308] Examples of alkyl groups include alkyl groups (preferably alkyl groups with 1 to 20 carbon atoms, such as methyl, ethyl, isopropyl, tert-butyl, pentyl, heptyl, 1-ethylpentyl, benzyl, 2-ethoxyethyl, 1-carboxymethyl, etc.), alkenyl groups (preferably alkenyl groups with 2 to 20 carbon atoms, such as vinyl, allyl, oleyl, etc.), alkynyl groups (preferably alkynyl groups with 2 to 20 carbon atoms, such as ethynyl, butyrynyl, phenylethynyl, etc.), and cycloalkyl groups (preferably cycloalkyl groups with 3 to 20 carbon atoms, such as cyclopropyl, cyclopentyl, cyclohexyl, 4-methylcyclohexyl, etc.). When the alkyl group is used in this invention, it is generally... The term usually indicates the presence of cycloalkyl groups, but is described separately here. Aryl groups (preferably aryl groups with 6 to 26 carbon atoms, such as phenyl, 1-naphthyl, 4-methoxyphenyl, 2-chlorophenyl, 3-methylphenyl, etc.), aralkyl groups (preferably aralkyl groups with 7 to 23 carbon atoms, such as benzyl, phenethyl, etc.), and heterocyclic groups (preferably heterocyclic groups with 2 to 20 carbon atoms, more preferably heterocyclic groups with a 5 or 6-membered ring having at least one oxygen atom, sulfur atom, and nitrogen atom). Heterocyclic groups include aromatic heterocyclic groups and aliphatic heterocyclic groups. For example, tetrahydropyranyl, tetrahydrofuranyl, 2-pyridyl, etc. 4-pyridinyl, 2-imidazolyl, 2-benzimidazolyl, 2-thiazolyl, 2-oxazolyl, pyrrolidone, etc.), alkoxy groups (preferably alkoxy groups with 1 to 20 carbon atoms, such as methoxy, ethoxy, isopropoxy, benzyloxy, etc.), aryloxy groups (preferably aryloxy groups with 6 to 26 carbon atoms, such as phenoxy, 1-naphthoxy, 3-methylphenoxy, 4-methoxyphenoxy, etc.), heterocyclic oxy groups (groups with -O- groups bonded to the above heterocyclic groups), alkoxycarbonyl groups (preferably alkoxycarbonyl groups with 2 to 20 carbon atoms, such as ethoxycarbonyl, 2-ethylhexyloxycarbonyl, deca-hydroxycarbonyl, etc.). Dialkoxycarbonyl, etc.), aryloxycarbonyl (preferably aryloxycarbonyl with 6 to 26 carbon atoms, such as phenoxycarbonyl, 1-naphthoxycarbonyl, 3-methylphenoxycarbonyl, 4-methoxyphenoxycarbonyl, etc.), heterocyclic oxycarbonyl (a group with -O-CO- group bonded to the above heterocyclic group), amino (preferably containing amino, alkylamino, arylamino with 0 to 20 carbon atoms, such as amino(-NH2), N,N-dimethylamino, N,N-diethylamino, N-ethylamino, aniline, etc.), aminosulfonyl (preferably aminosulfonyl with 0 to 20 carbon atoms, such as N,N-dimethylaminosulfonyl, N-phenylaminosulfonyl, etc.), acyl groups (including alkyl carbonyl, alkenyl carbonyl, alkynyl carbonyl, aryl carbonyl, heterocyclic carbonyl, preferably acyl groups with 1 to 20 carbon atoms, such as acetyl, propionyl, butyryl, octanoyl, hexadecanoyl, acryl, methacryl, crotonyl, benzoyl, naphthoyl, nicotinyl, etc.), acyloxy groups (including alkyl carbonyloxy, alkenyl carbonyloxy, alkynyl carbonyloxy, heterocyclic carbonyloxy, preferably acyloxy groups with 1 to 20 carbon atoms, such as acetyloxy, propionyloxy, butyryloxy, octanoyloxy, hexadecanoyl, etc.), Acryloyloxy, methacryloyloxy, crotonyloxy, nicotinoxy, etc.), aromatic acryloyloxy (preferably aromatic acryloyloxy with 7 to 23 carbon atoms, such as benzoyloxy, naphthyloxy, etc.), carbamoyl (preferably carbamoyl with 1 to 20 carbon atoms, such as N,N-dimethylcarbamoyl, N-phenylcarbamoyl, etc.), amide (preferably amide with 1 to 20 carbon atoms, such as acetamido, benzoylamino, etc.), alkylthio (preferably alkylthio with 1 to 20 carbon atoms, such as methylthio, ethylthio, isopropylthio, benzylthio, etc.) Arylthioyl (preferably arylthioyl with 6 to 26 carbon atoms, such as phenylthioyl, 1-naphthioyl, 3-methylphenylthioyl, 4-methoxyphenylthioyl, etc.), heterocyclic thioyl (a group with -S- group bonded to the above heterocyclic group), alkylsulfonyl (preferably alkylsulfonyl with 1 to 20 carbon atoms, such as methylsulfonyl, ethylsulfonyl, etc.), arylsulfonyl (preferably arylsulfonyl with 6 to 22 carbon atoms, such as benzenesulfonyl, etc.), alkylsilyl (preferably alkylsilyl with 1 to 20 carbon atoms, such as monomethylsilyl, dimethylsilyl, trimethylsilyl, etc.). alkylsilyl, triethylsilyl, etc.), arylsilyl (preferably arylsilyl with 6 to 42 carbon atoms, such as triphenylsilyl), alkoxysilyl (preferably alkoxysilyl with 1 to 20 carbon atoms, such as monomethoxysilyl, dimethoxysilyl, trimethoxysilyl, triethoxysilyl, etc.), aryloxysilyl (preferably aryloxysilyl with 6 to 42 carbon atoms, such as triphenoxysilyl), phosphoryl (preferably phosphoric acid with 0 to 20 carbon atoms, such as -OP(=O)(R, P )2) Phosphonyl group (preferably a phosphonyl group with 0 to 20 carbon atoms, for example, -P(=O)(R P )2) Oxyphosphin group (preferably oxyphosphin group with 0 to 20 carbon atoms, for example, -P(R P 2) Phosphonic acid group (preferably a phosphonic acid group with 0 to 20 carbon atoms, for example, -PO(OR) P 2) Sulfonate (sulfonic acid group), carboxyl group, hydroxyl group, thioalkyl group, cyano group, halogen atom (e.g., fluorine atom, chlorine atom, bromine atom, iodine atom, etc.). R PIt is a hydrogen atom or a substituent (preferably a group selected from substituent Z).

[0309] Furthermore, each of the groups listed in these substituents Z can be further replaced by the aforementioned substituents Z.

[0310] The aforementioned alkyl, alkylene, alkenyl, alkenylene, ynyl and / or ynylene groups can be cyclic or chain-like, and can be straight-chain or branched.

[0311] Specific examples of linear polymers include those synthesized in the examples, as well as the polymers shown below; however, the present invention is not limited to these. Furthermore, in the specific examples below, the content of the constituent components is appropriately set considering factors such as the radius of rotation α and the SP value.

[0312] [Chemical Formula 3]

[0313]

[0314] The polymer binder may contain one or more linear polymers. Furthermore, the polymer binder may contain other polymers, provided that the function of the linear polymers is not impaired. Among these other polymers, polymers commonly used as binders in all-solid-state secondary batteries can be used without particular restriction.

[0315] The electrode composition may contain one or more binders.

[0316] The content of the binder in the electrode composition is not particularly limited, but from the viewpoint of improving dispersibility and suppressing the decrease in ionic conductivity, and thus enhancing the adhesion of solid particles, it is preferably 0.05 to 8.0% by mass, more preferably 0.1 to 6.0% by mass, even more preferably 0.2 to 4.0% by mass, and especially preferably 0.2 to 1.0% by mass. Furthermore, the content of the binder in 100% by mass of the solid components of the electrode composition is preferably 0.1 to 10.0% by mass, more preferably 0.2 to 8% by mass, even more preferably 0.3 to 6.0% by mass, and especially preferably 0.3 to 1.0% by mass, for the same reason.

[0317] In this invention, the mass ratio of the total mass (total amount) of the inorganic solid electrolyte and the active material to the mass of the polymer binder in 100% by mass of the solid component [(mass of inorganic solid electrolyte + mass of active material) / (mass of polymer binder)] is preferably in the range of 1,000 to 1. Furthermore, this ratio is more preferably 500 to 2, and even more preferably 100 to 10.

[0318] <Dispersion Medium>

[0319] The electrode composition of the present invention contains a dispersion medium that disperses or dissolves the above-mentioned components.

[0320] As such a dispersion medium, any organic compound that appears as a liquid in the environment of use can be used, such as various organic solvents, specifically alcohols, ethers, amides, amines, ketones, aromatics, aliphatic compounds, nitriles, esters, etc.

[0321] The dispersion medium can be a nonpolar dispersion medium (hydrophobic dispersion medium) or a polar dispersion medium (hydrophilic dispersion medium). From the viewpoint of exhibiting excellent dispersibility, a nonpolar dispersion medium is preferred. A nonpolar dispersion medium generally refers to a medium with low affinity for water; however, in this invention, examples include ester compounds, ketone compounds, ether compounds, aromatic compounds, and aliphatic compounds.

[0322] Examples of alcohol compounds include, for example, methanol, ethanol, 1-propanol, 2-propanol, 2-butanol, ethylene glycol, propylene glycol, glycerol, 1,6-hexanediol, cyclohexanediol, sorbitol, xylitol, 2-methyl-2,4-pentanediol, 1,3-butanediol, and 1,4-butanediol.

[0323] Examples of ether compounds include alkylene glycols (diethylene glycol, triethylene glycol, polyethylene glycol, dipropylene glycol, etc.), alkylene glycol monoalkyl ethers (ethylene glycol monomethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, tripropylene glycol monomethyl ether, diethylene glycol monobutyl ether, etc.), alkylene glycol dialkyl ethers (ethylene glycol dimethyl ether, etc.), dialkyl ethers (dimethyl ether, diethyl ether, diisopropyl ether, dibutyl ether, etc.), and cyclic ethers (tetrahydrofuran, dioxanes (including 1,2-, 1,3- and 1,4- isomers, etc.)).

[0324] Examples of amide compounds include, for example, N,N-dimethylformamide, N-methyl-2-pyrrolidone, 2-pyrrolidone, 1,3-dimethyl-2-imidazolinone, ε-caprolactam, formamide, N-methylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, N-methylpropaneamide, hexamethylphosphoric triamide, etc.

[0325] Examples of amine compounds include triethylamine, diisopropylethylamine, and tri-n-butylamine.

[0326] Examples of ketone compounds include acetone, methyl ethyl ketone, methyl isobutyl ketone (MIBK), cyclopentanone, cyclohexanone, cycloheptanone, dipropyl ketone, dibutyl ketone, diisopropyl ketone, diisobutyl ketone (DIBK), isobutylpropyl ketone, sec-butylpropyl ketone, pentylpropyl ketone, butylpropyl ketone, etc.

[0327] Examples of aromatic compounds include, for example, benzene, toluene, xylene, and perfluorotoluene.

[0328] Examples of aliphatic compounds include hexane, heptane, octane, nonane, decane, dodecane, cyclohexane, methylcyclohexane, ethylcyclohexane, cycloheptane, cyclooctane, decahydronaphthalene, paraffin wax, gasoline, naphtha, kerosene, and light oil.

[0329] Examples of nitrile compounds include acetonitrile, propionitrile, and isobutyronitrile.

[0330] Examples of ester compounds include, for example, ethyl acetate, propyl acetate, butyl acetate, ethyl butyrate, propyl butyrate, isopropyl butyrate, butyl butyrate, isobutyl butyrate, butyl valerate, pentyl valerate, ethyl isobutyrate, propyl isobutyrate, isopropyl isobutyrate, isobutyl isobutyrate, propyl neovalerate, isopropyl neovalerate, butyl neovalerate, isobutyl neovalerate, etc.

[0331] In this invention, ether compounds, ketone compounds, aromatic compounds, aliphatic compounds, and ester compounds are preferred, and ester compounds, ketone compounds, aromatic compounds, or ether compounds are more preferred.

[0332] There is no particular limitation on the number of carbon atoms in the compound constituting the dispersion medium, but it is preferably 2 to 30, more preferably 4 to 20, even more preferably 6 to 15, and especially preferably 7 to 12.

[0333] The dispersion medium is considered from the perspective of the dispersibility of solid particles, for example, the SP value (unit: MPa). 1 / 2 The SP value is preferably 14 to 24, more preferably 15 to 22, and even more preferably 17 to 20. There is no particular limitation on the absolute value of the difference between the dispersion medium and the linear polymer SP value; for example, it can be set to 7.0 or less. However, considering that the molecular chains of the linear polymer extend in the dispersion medium to improve its own dispersibility, thereby further improving the dispersibility of solid particles, it is preferably 3 or less, more preferably 0 to 2, and even more preferably 0 to 1.

[0334] The SP value of the dispersion medium is set to be the SP value calculated by the Hoy method above, converted to MPa. 1 / 2 The SP value is obtained as follows. When the electrode composition contains two or more dispersion media, the SP value of the dispersion media refers to the SP value of the entire dispersion media, and is set as the sum of the products of the SP value of each dispersion media and its mass fraction. Specifically, except that the SP value of each dispersion media is used instead of the SP value of the constituent components, it is calculated in the same way as the SP value of the polymer described above.

[0335] The following shows the SP values ​​(units omitted) of the main dispersion media.

[0336] MIBK (18.4), diisopropyl ether (16.8), dibutyl ether (17.9), diisobutyl ketone (17.9), DIBK (17.9), butyl butyrate (18.6), butyl acetate (18.9), toluene (18.5), ethylcyclohexane (17.1), cyclooctane (18.8), isobutyl ethyl ether (15.3), N-methylpyrrolidone (NMP, 25.4), perfluorotoluene (13.4)

[0337] The boiling point of the dispersion medium at atmospheric pressure (1 atmosphere) is preferably 50°C or higher, more preferably 70°C or higher. The upper limit is preferably 250°C or lower, and even more preferably 220°C or lower.

[0338] The electrode composition of the present invention may contain one or more dispersion media. Examples of containing two or more dispersion media include mixed xylenes (a mixture of o-xylene, p-xylene, m-xylene, and ethylbenzene).

[0339] In this invention, the content of the dispersion medium in the electrode composition is not particularly limited and can be appropriately set. For example, the content is preferably 10-80% by mass, more preferably 30-70% by mass, and particularly preferably 40-60% by mass in the electrode composition.

[0340] The electrode composition of the present invention contains an inorganic solid electrolyte, an active material, and a polymer binder that satisfy the above-described relationships. Therefore, a high solid content concentration (reducing the content of the dispersion medium) can be achieved without compromising dispersibility, etc. For example, the content of the dispersion medium in the electrode composition can be set to 40% by mass or less, and can be reduced to 30% by mass or less. The lower limit of this content is actually 5% by mass or more, preferably 10% by mass or more. With this electrode composition that increases the solid content concentration, an active material layer with a thicker layer suitable for high energy density can be formed.

[0341] <Conductive additives>

[0342] The electrode composition of the present invention preferably contains a conductive additive, for example, a silicon-containing active material as a negative electrode active material is used in combination with the conductive additive.

[0343] There are no particular restrictions on the conductive additives used; any conductive additives known to be used as conductive additives can be used. For example, they can be graphite materials such as natural graphite and artificial graphite, carbon black such as acetylene black, Ketjen black, and furnace black, amorphous carbon such as needle coke, carbon fiber materials such as vapor-grown carbon fibers or carbon nanotubes, carbonaceous materials such as graphene or fullerene, metal powders such as copper and nickel, metal fibers, or conductive polymers such as polyaniline, polypyrrole, polythiophene, polyacetylene, and polyphenylene derivatives.

[0344] In this invention, when active materials and conductive additives are used in combination, the conductive additives that do not produce the insertion and extraction of metal ions (preferably Li ions) belonging to Group I or Group II of the periodic table during battery charging and discharging, and do not function as active materials, are classified as conductive additives. Therefore, among conductive additives, those that can function as active materials in the active material layer during battery charging and discharging are classified as active materials rather than conductive additives. Whether an additive functions as an active material during battery charging and discharging is determined by its combination with active materials, rather than by a general rule.

[0345] The conductive additive contained in the electrode composition of the present invention may be one type or two or more types.

[0346] There are no particular restrictions on the shape of the conductive additive, but it is preferably in particulate form.

[0347] When the electrode composition of the present invention contains a conductive additive, the content of the conductive additive in the electrode composition is preferably 0 to 10% by mass of 100% by mass of the solid component, more preferably 0 to 5% by mass.

[0348] <Lithium Salts>

[0349] The electrode composition of the present invention preferably contains a lithium salt (supporting electrolyte).

[0350] As a lithium salt, the lithium salt commonly used in this product is preferred, and there are no particular restrictions. For example, the lithium salt described in paragraphs 0082 to 0085 of Japanese Patent Application Publication No. 2015-088486 is preferred.

[0351] When the electrode composition of the present invention contains a lithium salt, the content of the lithium salt relative to 100 parts by weight of the solid electrolyte is preferably 0.1 parts by weight or more, more preferably 5 parts by weight or more. As an upper limit, it is preferably 50 parts by weight or less, more preferably 20 parts by weight or less.

[0352] <Dispersant>

[0353] Since the aforementioned polymer binder also functions as a dispersant, the electrode composition of the present invention may or may not contain a dispersant other than the polymer binder. As a dispersant, a dispersant commonly used in all-solid-state secondary batteries can be suitably selected. Typically, compounds suitable for particle adsorption, steric hindrance, and / or electrostatic repulsion are used.

[0354] <Other Additives>

[0355] The electrode composition of the present invention can appropriately contain ionic liquids, thickeners, polymerization initiators (substances that generate acids or free radicals by heat or light, etc.), defoamers, homogenizers, dehydrating agents, antioxidants, etc., as other components besides those mentioned above. Ionic liquids are liquids contained to further improve ionic conductivity, and known liquids can be used without particular limitation. Furthermore, polymers other than the aforementioned linear polymers, commonly used binders, etc., can be included.

[0356] (Preparation of electrode composition)

[0357] The electrode composition of the present invention can be prepared, for example, by mixing an inorganic solid electrolyte, an active material, the aforementioned polymer binder, a dispersion medium, preferably a conductive additive, and a suitable lithium salt and any other components using various commonly used mixers, as a mixture, preferably as a slurry.

[0358] There are no particular limitations on the mixing method; any known mixer, such as a ball mill, bead mill, planetary mixer, scraper mixer, roller mill, kneader, disc mill, rotary-revolutionary mixer, or narrow-gap disperser, can be used. The components can be mixed all at once or sequentially. There are no particular limitations on the mixing environment; dry air or inert gas conditions are acceptable. Furthermore, there are no particular limitations on the mixing conditions, which can be appropriately set.

[0359] Electrode sheets for all-solid-state rechargeable batteries

[0360] The electrode sheet for all-solid-state secondary batteries of the present invention (sometimes simply referred to as electrode sheet) is a sheet-shaped molded body capable of forming active material or electrode (a laminate of active material layer and current collector) for all-solid-state secondary batteries, and includes various forms depending on its application.

[0361] The electrode sheet of the present invention has an active material layer composed of the electrode composition of the present invention on the surface of a substrate. Therefore, even when manufactured by industrial methods, such as high-yield roll-to-roll methods, the electrode sheet of the present invention has an active material layer with uniform thickness and a defined shape. This electrode sheet is used as an active material layer in an all-solid-state secondary battery, and as an electrode in an all-solid-state secondary battery when a current collector is used as the substrate.

[0362] The electrode sheet of the present invention is simply an electrode sheet having an active material layer on the surface of a substrate. Furthermore, the electrode sheet may also include a form having a substrate, an active material layer, and a solid electrolyte layer in sequence, or a form having a substrate, an active material layer, a solid electrolyte layer, and an active material layer in sequence. The electrode sheet may also have other layers besides the aforementioned layers. Examples of other layers include, for instance, a protective layer (release film), a coating, etc.

[0363] As for the substrate, there are no particular limitations as long as it is a substrate capable of supporting the active material layer. Examples include the materials described in the current collector section, organic materials, inorganic materials, and sheet-like materials. Examples of organic materials include various polymers, specifically polyethylene terephthalate, polypropylene, polyethylene, and cellulose. Examples of inorganic materials include, for example, glass and ceramics.

[0364] The active material layer is formed from the electrode composition of the present invention. In the active material layer formed from the electrode composition of the present invention, the content of each component is not particularly limited, but preferably has the same meaning as the content of each component in the solid components of the electrode composition of the present invention. The layer thickness of each layer constituting the electrode sheet of the present invention is the same as the layer thickness described later in the description of all-solid-state secondary batteries.

[0365] In this invention, each layer constituting the sheet for all-solid-state secondary batteries can be a single-layer structure or a multi-layer structure.

[0366] Furthermore, the solid electrolyte layer, and in other words, the active material layer formed by the electrode composition of the present invention, is formed by a conventional constituent layer forming material.

[0367] In the electrode sheet of the present invention, the active material layer on the surface of the substrate is formed by the electrode composition of the present invention. Therefore, by using the electrode sheet of the present invention as an active material layer in an all-solid-state secondary battery and as an electrode in an all-solid-state secondary battery when using a current collector as a substrate, an all-solid-state secondary battery exhibiting high ionic conductivity (low resistance) can be realized.

[0368] The all-solid-state electrode sheet of the present invention, even when manufactured industrially, such as by a high-efficiency roll-to-roll method, possesses an active material layer with uniform thickness and a defined shape. Furthermore, the all-solid-state electrode sheet of the present invention can be directly used as an electrode for an all-solid-state secondary battery (without cutting off the end edges of the sheet). Using this all-solid-state electrode sheet as an electrode reduces production costs and facilitates the manufacture of low-resistance all-solid-state secondary batteries with high ion conductivity, particularly for industrial applications. Therefore, the all-solid-state electrode sheet of the present invention is suitable as a sheet material capable of forming electrodes for all-solid-state secondary batteries. In the present invention, the active material layer with uniform thickness and a defined shape is an active material layer formed to suppress liquid dripping and uneven coating of the electrode composition, and can be evaluated as described in the examples.

[0369] [Manufacturing method of electrode sheets for all-solid-state secondary batteries]

[0370] The manufacturing method of the electrode sheet for all-solid-state secondary batteries of the present invention is not particularly limited. For example, a method can be described as forming a layer (coating and drying layer) of the electrode composition of the present invention on the surface of a substrate (or with other layers in between). This allows the production of a sheet having a substrate and a coating and drying layer. Here, the coating and drying layer refers to a layer formed by coating the electrode composition of the present invention and drying the dispersion medium (i.e., a layer formed using the electrode composition of the present invention and consisting of a composition from which the dispersion medium is removed). The dispersion medium may remain in the coating and drying layer or the active material layer composed of the coating and drying layer, provided it does not impair the effects of the present invention. The residual amount can, for example, be 3% by mass or less in each layer.

[0371] In the manufacturing method of the electrode sheet for all-solid-state secondary battery of the present invention, each step such as coating and drying will be described in the following manufacturing method of all-solid-state secondary battery.

[0372] In this way, it is possible to manufacture electrode sheets for all-solid-state secondary batteries that have an active material layer consisting of a coated and dried layer, or an active material layer formed by appropriately pressurizing the coated and dried layer. The pressurization conditions for the coated and dried layer will be explained in the manufacturing method of all-solid-state secondary batteries described later.

[0373] Furthermore, in the manufacturing method of the all-solid-state secondary battery sheet of the present invention, it is also possible to peel off the substrate, protective layer (especially the sheet), etc.

[0374] [All-solid-state rechargeable battery]

[0375] The all-solid-state secondary battery of the present invention comprises a positive electrode active material layer, a negative electrode active material layer opposite to the positive electrode active material layer, and a solid electrolyte layer disposed between the positive electrode active material layer and the negative electrode active material layer. The all-solid-state secondary battery of the present invention is only required to have a structure with a solid electrolyte layer between the positive electrode active material layer and the negative electrode active material layer; other structures are not particularly limited, for example, known structures related to all-solid-state secondary batteries can be used. The positive electrode active material layer is preferably formed on a positive electrode current collector and constitutes the positive electrode. The negative electrode active material layer is preferably formed on a negative electrode current collector and constitutes the negative electrode.

[0376] Preferably, at least one of the negative electrode active material layer and the positive electrode active material layer is formed by the electrode composition of the present invention. The all-solid-state secondary battery of the present invention, in which at least one of the negative electrode active material layer and the positive electrode active material layer is formed by the electrode composition of the present invention, exhibits high ionic conductivity (low resistance) and is capable of extracting large currents, even when manufactured using an industrially advantageous roll-to-roll method.

[0377] Regarding the types and amounts of components contained therein, the active material layer formed by the electrode composition of the present invention is preferably the same as that in the solid components of the electrode composition of the present invention. Alternatively, when the active material layer or the solid electrolyte layer is not formed by the electrode composition of the present invention, known materials can be used.

[0378] In this invention, each constituent layer (including current collectors, etc.) constituting the all-solid-state secondary battery can be a single-layer structure or a multi-layer structure.

[0379] <Positive electrode active material layer and negative electrode active material layer>

[0380] There are no particular limitations on the thickness of each of the negative electrode active material layer and the positive electrode active material layer. Considering the size of a typical all-solid-state secondary battery, the thickness of each layer is preferably 10 to 1,000 μm, more preferably 20 μm or more and less than 500 μm. In the all-solid-state secondary battery of the present invention, the thickness of at least one of the positive electrode active material layer and the negative electrode active material layer is further preferably 50 μm or more and less than 500 μm.

[0381] The active material layer having the above-mentioned thickness can be a single layer (one-time coating of the electrode composition) or a multilayer (multiple coatings of the electrode composition). However, from the perspective of reducing resistance and improving productivity, it is preferable to use the electrode composition of the present invention, which is capable of being thickened, to form a single layer of active material with a large layer thickness. Preferably, the layer thickness of the active material capable of forming a thickened single layer of the electrode composition of the present invention can be set to, for example, 70 μm or more, and furthermore, it can be set to 100 μm or more.

[0382] <Solid Electrolyte Layer>

[0383] The solid electrolyte layer is formed using a known material capable of forming a solid electrolyte layer for an all-solid-state secondary battery. Its thickness is not particularly limited, but is preferably 10 to 1,000 μm, more preferably 20 μm or more and less than 500 μm.

[0384] <Current Collector>

[0385] Both the positive and negative electrode active material layers may have current collectors on the opposite side of the solid electrolyte layer. These positive and negative electrode current collectors are preferably electron conductors.

[0386] In this invention, either the positive current collector or the negative current collector, or both together, are sometimes referred to simply as a current collector.

[0387] In addition to aluminum, aluminum alloys, stainless steel, nickel, and titanium, materials in which carbon, nickel, titanium, or silver (materials forming thin films) are treated on the surface of aluminum or stainless steel are preferred as the material forming the positive current collector. Among these, aluminum and aluminum alloys are more preferred.

[0388] In addition to aluminum, copper, copper alloys, stainless steel, nickel, and titanium, materials that have been treated with carbon, nickel, titanium, or silver on the surface of aluminum, copper, copper alloys, or stainless steel are preferred as materials for forming the negative current collector. More preferably, aluminum, copper, copper alloys, and stainless steel are preferred.

[0389] Current collectors are typically in the form of a membrane, but can also be made of mesh, perforated material, lath, porous material, foam, or fiber assembly.

[0390] There is no particular limitation on the thickness of the current collector, but it is preferably 1 to 500 μm. Furthermore, it is also preferable to have irregularities on the surface of the current collector through surface treatment.

[0391] <Other Structures>

[0392] In this invention, functional layers or components may be appropriately inserted or disposed between or on the outside of the layers of the negative electrode current collector, the negative electrode active material layer, the solid electrolyte layer, the positive electrode active material layer, and the positive electrode current collector.

[0393] <Frame>

[0394] The all-solid-state secondary battery of the present invention can be used as an all-solid-state secondary battery in the above-described structural state depending on the application, but in order to make it into a dry cell form, it is preferable to further enclose it in a suitable casing. The casing can be a metallic casing or a resin (plastic) casing. When using a metallic casing, for example, a casing made of aluminum alloy or stainless steel can be cited. Preferably, the metallic casing is divided into a positive electrode side casing and a negative electrode side casing, which are electrically connected to the positive electrode current collector and the negative electrode current collector, respectively. Preferably, the positive electrode side casing and the negative electrode side casing are joined together as one piece with a short-circuit prevention gasket.

[0395] The following is for reference. Figure 1 The preferred embodiments of the present invention will be described, but the present invention is not limited thereto.

[0396] Figure 1 This is a schematic cross-sectional view illustrating a preferred embodiment of the all-solid-state secondary battery (lithium-ion secondary battery) of the present invention. Viewed from the negative electrode side, the all-solid-state secondary battery 10 of this embodiment sequentially comprises a negative electrode current collector 1, a negative electrode active material layer 2, a solid electrolyte layer 3, a positive electrode active material layer 4, and a positive electrode current collector 5. Each layer is in contact with the others and has an adjacent structure. By employing such a structure, electrons (electrons) are supplied to the negative electrode side during charging. - ), and accumulate lithium ions (Li) here. + On the other hand, during discharge, lithium ions (Li) accumulated at the negative electrode... + The electrons return to the positive side and supply electrons to the working part 6. In the illustrated example, a light bulb is used as a model in the working part 6, and the bulb is lit by discharging.

[0397] In having Figure 1 When the all-solid-state secondary battery with the layered structure shown is placed in a 2032-type button cell, it is sometimes referred to as the all-solid-state secondary battery laminate 12. A battery manufactured by placing this all-solid-state secondary battery laminate 12 into a 2032-type button cell 11 (for example, ...) Figure 2 The button-type all-solid-state secondary battery shown is called an all-solid-state secondary battery 13.

[0398] (Solid electrolyte layer)

[0399] The solid electrolyte layer can use materials that have been used in conventional all-solid-state secondary batteries without particular limitations. This solid electrolyte layer typically contains an inorganic solid electrolyte having ionic conductivity of a metal belonging to Group 1 or Group 2 of the periodic table, and any of the aforementioned components within the scope that does not impair the effects of this invention; it generally does not contain active materials.

[0400] (Positive electrode active material layer and negative electrode active material layer)

[0401] In the all-solid-state secondary battery 10, both the positive electrode active material layer and the negative electrode active material layer are formed from the electrode composition of the present invention. Preferably, the positive electrode, which is formed by stacking the positive electrode active material layer and the positive electrode current collector, and the negative electrode, which is formed by stacking the negative electrode active material layer and the negative electrode current collector, are formed from the electrode sheet of the present invention using the current collector as a substrate.

[0402] The positive electrode active material layer contains an inorganic solid electrolyte having the ionic conductivity of a metal belonging to Group I or Group II of the periodic table, a positive electrode active material, a polymer binder, and any of the above-mentioned components within the scope that does not impair the effects of the present invention.

[0403] The negative electrode active material layer contains an inorganic solid electrolyte having ionic conductivity of a metal belonging to Group I or Group II of the periodic table, a negative electrode active material, a polymer binder, and any of the above-mentioned components within the range that does not impair the effects of the present invention. In the all-solid-state secondary battery 10, the negative electrode active material layer can be a lithium metal layer. Examples of lithium metal layers include layers formed by stacking or molding lithium metal powder, lithium foil, and lithium vapor-deposited films. The thickness of the lithium metal layer is independent of the aforementioned thickness of the negative electrode active material layer, and for example, can be set to 1 to 500 μm.

[0404] The inorganic solid electrolyte and polymer binder contained in the positive electrode active material layer 4, the solid electrolyte layer 3 and the negative electrode active material layer 2 can be of the same type or different types.

[0405] In this invention, when the active material layer is formed from the electrode composition of this invention, an all-solid-state secondary battery exhibiting high ionic conductivity (low resistance) can be realized even when manufactured by an industrially advantageous roll-to-roll method.

[0406] (Current collector)

[0407] The positive current collector 5 and the negative current collector 1 are as described above.

[0408] [Manufacturing of all-solid-state rechargeable batteries]

[0409] All-solid-state secondary batteries can be manufactured using conventional methods. Specifically, all-solid-state secondary batteries can be manufactured by forming at least one active material layer using the electrode composition of the present invention, and forming a solid electrolyte layer, another suitable active material layer, or an electrode using known materials.

[0410] The all-solid-state secondary battery of the present invention can be manufactured by a method comprising the steps of coating the electrode composition of the present invention onto the surface of a substrate (e.g., a metal foil that serves as a current collector) and drying it to form a coating film (film forming).

[0411] For example, a positive electrode active material layer is formed by forming an electrode composition containing a positive electrode active material (positive electrode composition) on a metal foil serving as the positive electrode current collector to produce a positive electrode sheet for an all-solid-state secondary battery. Next, a solid electrolyte layer is formed by forming a solid electrolyte composition for forming a solid electrolyte layer on this positive electrode active material layer. Furthermore, a negative electrode active material layer is formed by forming an electrode composition containing a negative electrode active material (negative electrode composition) on the solid electrolyte layer. By overlapping a negative electrode current collector (metal foil) on the negative electrode active material layer, an all-solid-state secondary battery with a structure in which the solid electrolyte layer is sandwiched between the positive and negative electrode active material layers can be obtained. It can also be encapsulated in a casing to form a desired all-solid-state secondary battery.

[0412] Furthermore, in contrast to the methods for forming each layer, it is also possible to manufacture an all-solid-state secondary battery by forming a negative electrode active material layer, a solid electrolyte layer, and a positive electrode active material layer on the negative electrode current collector and then overlapping the positive electrode current collector.

[0413] As another method, the following approach can be used: The positive electrode sheet for an all-solid-state secondary battery is fabricated as described above. Furthermore, an electrode composition containing a negative electrode active material (negative electrode composition) is formed on a metal foil serving as the negative electrode current collector to create a negative electrode active material layer, thus fabricating the negative electrode sheet for an all-solid-state secondary battery. Next, a solid electrolyte layer is formed on the active material layer of any one of these sheets, as described above. Then, the positive electrode sheet for an all-solid-state secondary battery and another negative electrode sheet for an all-solid-state secondary battery are stacked on the solid electrolyte layer in such a way that the solid electrolyte layer and the active material layer are in contact. In this way, an all-solid-state secondary battery can be manufactured.

[0414] Furthermore, as another method, the following can be cited: That is, to manufacture the positive electrode sheet and the negative electrode sheet for an all-solid-state secondary battery as described above. In addition, a solid electrolyte sheet for an all-solid-state secondary battery, consisting of a solid electrolyte layer, can be manufactured by forming a film of a composition containing an inorganic solid electrolyte on a substrate. Moreover, the solid electrolyte layer, which has been peeled off from the substrate, is stacked in a manner where the positive electrode sheet and the negative electrode sheet for an all-solid-state secondary battery are sandwiched between them. In this way, an all-solid-state secondary battery can be manufactured.

[0415] Furthermore, as another method, as described above, a positive electrode sheet or a negative electrode sheet for an all-solid-state secondary battery and a solid electrolyte sheet for an all-solid-state secondary battery are fabricated. Next, the positive electrode sheet or a negative electrode sheet and the solid electrolyte sheet are overlapped while the positive electrode active material layer or a negative electrode active material layer is in contact with the solid electrolyte layer, and pressure is applied. This transfers the solid electrolyte layer onto the positive electrode sheet or the negative electrode sheet. Then, the solid electrolyte layer obtained by peeling off the substrate of the solid electrolyte sheet and the negative electrode sheet or the positive electrode sheet (while the negative electrode active material layer or the positive electrode active material layer is in contact with the solid electrolyte layer) are overlapped and pressure is applied. In this way, an all-solid-state secondary battery can be manufactured. There are no particular limitations on the pressure application method and conditions in this method; the methods and conditions described in the pressure application process described later can be used.

[0416] The active material layer, for example, can also be used to form an electrode composition by pressure molding on a substrate or active material layer under pressure conditions described later, or a sheet molded body can also be used.

[0417] In the above manufacturing method, either the positive electrode composition or the negative electrode composition can use the electrode composition of the present invention, and both the positive electrode composition and the negative electrode composition can use the electrode composition of the present invention.

[0418] When an active material layer is formed from a composition other than the electrode composition of the present invention, commonly used compositions and the like can be cited as materials. Furthermore, in the manufacture of an all-solid-state secondary battery, instead of forming a negative electrode active material layer, ions of metals belonging to Group I or Group II of the periodic table accumulated in the negative electrode current collector during initialization or charging (described later) combine with electrons, and are deposited as metal on the negative electrode current collector, thereby forming a negative electrode active material layer.

[0419] <Formation of each layer (film formation)>

[0420] There are no particular limitations on the coating method for each composition, and it can be appropriately selected. For example, coating (preferably wet coating), spraying, spin coating, dip coating, slot coating, strip coating, and bar coating can be used.

[0421] It is preferable to perform a drying treatment (heat treatment) on the coated composition. The drying treatment can be performed after each coating of the composition or after multiple coatings. There are no particular limitations on the drying temperature; for example, 30°C or higher is preferred, more preferably 60°C or higher, and even more preferably 80°C or higher. There are no particular upper limits; preferably 300°C or lower, more preferably 250°C or lower, and even more preferably 200°C or lower. Heating within this temperature range allows the dispersion medium to be removed, resulting in a solid state (coated dried layer). Furthermore, this avoids excessively high temperatures and damage to the components of the all-solid-state secondary battery, which is therefore preferable. As a result, the all-solid-state secondary battery exhibits excellent overall performance and achieves good ionic conductivity.

[0422] After coating each composition, the layers are overlapped to form a solid-state secondary battery, or after fabrication of the all-solid-state secondary battery, each layer or the all-solid-state secondary battery is pressurized. Examples of pressurization methods include hydraulic cylinder presses. There are no particular limitations on the pressure applied, but a range of 5 to 1500 MPa is generally preferred.

[0423] Furthermore, the coated compositions can be heated simultaneously under pressure. There are no particular limitations on the heating temperature.

[0424] Generally, the temperature range is 30–300°C. Stamping can also be performed at temperatures higher than the glass transition temperature of the inorganic solid electrolyte. Additionally, stamping can be performed at temperatures higher than the glass transition temperature of the polymer contained in the polymer binder. However, the temperature is typically no higher than the melting point of the polymer.

[0425] Pressurization can be performed either with the solvent or dispersion medium pre-dried or with residual solvent or dispersion medium remaining.

[0426] Alternatively, the various compositions can be coated simultaneously, or the coating, drying, and stamping can be performed simultaneously and / or sequentially. They can be laminated by transfer printing after being coated onto their respective substrates.

[0427] There are no particular restrictions on the atmosphere used in film-forming methods (coating, drying, pressurization (under heating)). It can be any atmosphere, including atmospheric pressure, dry air (dew point below -20°C), or inert gases (e.g., argon, helium, nitrogen).

[0428] The stamping time can be either a short period of time (e.g., within a few hours) to apply high pressure, or a long period of time (more than one day) to apply medium pressure. In the case of solid-state secondary batteries, except for electrode sheets for all-solid-state secondary batteries, for example, the constraint tools of all-solid-state secondary batteries (screw tightening pressure, etc.) can be used to continuously apply medium pressure.

[0429] Compared to the pressure-bearing parts such as the surface of the sheet, the stamping pressure can be uniform or varying.

[0430] The stamping pressure can be varied according to the area or film thickness of the pressed part. Furthermore, it is also possible to apply different pressures to the same part in stages.

[0431] The stamped surface can be smooth or rough.

[0432] In this invention, the formation of the above-mentioned layers, especially the film formation of the electrode composition of this invention, can be carried out using a sheet substrate by a so-called batch process, or by a roll-to-roll process, which also has high productivity in industrial manufacturing methods.

[0433] Furthermore, the active material layer used to manufacture all-solid-state secondary batteries can be prepared by cutting and punching electrode sheets for all-solid-state secondary batteries, but from the viewpoint of reducing productivity and production costs, it is preferable to directly use the fabricated all-solid-state secondary battery sheets.

[0434] <Initialization>

[0435] All-solid-state secondary batteries manufactured in the manner described above are preferably initialized after manufacturing or before use. There are no particular limitations on initialization; for example, initial charging and discharging can be performed under increased stamping pressure, followed by releasing the pressure until the normal operating pressure of the all-solid-state secondary battery is reached.

[0436] Applications of all-solid-state rechargeable batteries

[0437] The all-solid-state secondary battery of this invention is applicable to a wide variety of uses. There are no particular limitations on its application; for example, when incorporated into electronic devices, it can be used in laptops, pen-and-paper computers, mobile computers, e-book readers, mobile phones, cordless phones, pagers, handheld terminals, portable fax machines, portable copiers, portable printers, stereo headphones, camcorders, LCD TVs, portable vacuum cleaners, portable CD players, mini disk drives, electric shavers, transceivers, electronic notebooks, calculators, memory cards, portable recorders, radios, backup power supplies, etc. As other civilian products, it can be used in automobiles (electric vehicles), electric vehicles, motors, lighting fixtures, toys, game consoles, load conditioners, clocks, flashlights, cameras, and medical devices (pacemakers, hearing aids, and shoulder massagers, etc.). Furthermore, it can be used in various military and aerospace applications. It can also be combined with solar cells.

[0438] Example

[0439] The present invention will now be described in further detail with reference to embodiments, but the invention is not limited thereto. In the following embodiments, unless otherwise specified, "parts" and "%" of composition refer to mass. In the present invention, "room temperature" refers to 25°C.

[0440] 1. Polymer synthesis and preparation of adhesive solutions or dispersions

[0441] The following were the synthesis of the following polymers with the chemical formulas described below and the polymers shown in Table 1.

[0442] [Synthetic Example S-1: Synthesis of Polymer S-1 and Preparation of Adhesive Solution S-1]

[0443] A monomer solution was prepared by adding 34.9 g of dodecyl acrylate (manufactured by Tokyo Chemical Industry Co., Ltd.), 1.1 g of maleic anhydride (manufactured by FUJIFILM Wako Pure Chemical Corporation), and 0.36 g of polymerization initiator V-601 (trade name, manufactured by FUJIFILM Wako Pure Chemical Corporation) to a 100 mL graduated cylinder and dissolving it in 36.0 g of butyl butyrate.

[0444] 18.0 g of butyl butyrate was added to a 300 mL three-necked flask, and the monomer solution was added dropwise over 2 hours at 80 °C with stirring. After the addition was complete, the temperature was raised to 90 °C and stirred for 2 hours. The resulting polymer solution was poured into 480 g of a water / acetone mixture (70 / 30 weight ratio), stirred for 10 minutes, and then allowed to stand for 10 minutes. The precipitate obtained after removing the supernatant was dissolved in 80 g of butyl butyrate, heated at 30 hPa and 60 °C for 1 hour, and methanol was removed by distillation.

[0445] Thus, by synthesizing polymer S-1 (a random copolymer of (meth)acrylic acid polymer), a solution S-1 (concentration 38% by mass) of an adhesive composed of polymer S-1 was obtained.

[0446] [Synthetic Example S-2: Synthesis of Polymer S-2 and Preparation of Adhesive Solution S-2]

[0447] 100 parts by mass of ion-exchanged water, 65 parts by mass of vinylidene fluoride, 20 parts by mass of hexafluoropropylene, and 15 parts by mass of tetrafluoroethylene were added to an autoclave. Then, 1 part by mass of the polymerization initiator PEROYL IPP (trade name, chemical name: diisopropyl peroxide, manufactured by NOF CORPORATION) was added, and the mixture was stirred at 40°C for 24 hours. After stirring, the precipitate was filtered and dried at 100°C for 10 hours. 150 parts by mass of butyl butyrate were added to 10 parts by mass of the obtained polymer and dissolved.

[0448] Thus, by synthesizing polymer S-2 (a fluorinated polymer of random copolymer), a solution S-2 (concentration 6.3% by mass) of adhesive composed of polymer S-2 was obtained.

[0449] [Synthetic Example S-3: Synthesis of Polymer S-3 and Preparation of Adhesive Solution S-3]

[0450] 100 parts by weight of ion-exchanged water, 70 parts by weight of vinylidene fluoride, and 30 parts by weight of hexafluoropropylene were added to an autoclave. 1 part by weight of PEROYL IPP (trade name, chemical name: diisopropyl peroxide, manufactured by NOFCORPORATION) as a polymerization initiator was further added, and the mixture was stirred at 40°C for 24 hours. After stirring, the precipitate was filtered and dried at 100°C for 10 hours. 40 parts by weight of butyl butyrate were added relative to 10 parts by weight of the obtained polymer and dissolved.

[0451] Thus, by synthesizing polymer S-3 (a fluorinated polymer of random copolymer), a solution S-3 (concentration 20% by mass) of adhesive composed of polymer S-3 was obtained.

[0452] [Synthetic Example S-4: Synthesis of Polymer S-4 and Preparation of Adhesive Solution S-4]

[0453] A monomer solution was prepared by adding 34.2 g of dodecyl acrylate (manufactured by Tokyo Chemical Industry Co., Ltd.), 1.8 g of monoisopropyl fumarate (manufactured by Tokyo Chemical Industry Co., Ltd.), and 0.36 g of polymerization initiator V-601 (trade name, manufactured by FUJIFILM Wako Pure Chemical Corporation) to a 100 mL graduated cylinder and dissolving them in 36.0 g of butyl butyrate.

[0454] 18.0 g of butyl butyrate was added to a 300 mL three-necked flask, and the monomer solution was added dropwise over 2 hours at 80 °C with stirring. After the addition was complete, the temperature was raised to 90 °C and stirred for 2 hours.

[0455] Thus, by synthesizing polymer S-4 (a random copolymer of (meth)acrylic acid polymer), a solution S-4 (concentration 40% by mass) of an adhesive composed of polymer S-4 was obtained.

[0456] [Synthetic Example S-5: Synthesis of Polymer S-5 and Preparation of Adhesive Solution S-5]

[0457] In Synthesis Example S-1, compounds that introduce each constituent component were used to make polymer S-5 have the composition shown in Table 1 (content of constituent components). The amount of V-601 added was changed to 1.08 g. Otherwise, polymer S-5 was synthesized in the same manner as in Synthesis Example S-1, and a solution S-5 of adhesive composed of the polymer was obtained.

[0458] [Synthetic Example S-6: Synthesis of Polymer S-6 and Preparation of Adhesive Solution S-6]

[0459] In Synthesis Example S-1, compounds that introduce each constituent component were used to make polymer S-6 have the composition shown in Table 1 (content of constituent components). The amount of V-601 added was changed to 3.16 g. Otherwise, polymer S-6 was synthesized in the same manner as in Synthesis Example S-1, and a solution S-6 of adhesive composed of the polymer was obtained.

[0460] [Synthetic Examples S-7 and S-8: Synthesis of polymers S-7 and S-8, and preparation of adhesive solutions S-7 and S-8]

[0461] In Synthesis Example S-1, compounds that introduce each constituent component are used to make polymers S-7 and S-8 have the composition (content of constituent components) shown in Table 1. Otherwise, polymers S-7 and S-8 are synthesized in the same manner as in Synthesis Example S-1, and solutions S-7 and S-8 of adhesives composed of each polymer are obtained respectively.

[0462] [Synthetic Example S-9: Synthesis of Polymer S-9 and Preparation of Adhesive Solution S-9]

[0463] In Synthesis Example S-6, compounds that introduce each constituent component are used to make polymer S-9 have the composition shown in Table 1 (types and amounts of constituent components). Otherwise, polymer S-9 is synthesized in the same manner as in Synthesis Example S-6, and a solution S-9 of adhesive composed of the polymer is obtained.

[0464] [Synthetic Example S-10: Synthesis of Polymer S-10 and Preparation of Adhesive Solution S-10]

[0465] In Synthesis Example S-2, the amount of Parroyl IPP added was changed to 0.1 parts by mass. Otherwise, polymer S-10 was synthesized in the same manner as in Synthesis Example S-2, and a solution S-10 of adhesive composed of the polymer was obtained.

[0466] [Synthetic Example S-11: Synthesis of Polymer S-11 and Preparation of Adhesive Dispersion S-11]

[0467] A monomer solution was prepared by adding 14.4 g of dodecyl methacrylate (manufactured by Tokyo Chemical Industry Co., Ltd.), 3.6 g of hydroxyethyl acrylate (manufactured by Tokyo Chemical Industry Co., Ltd.), 18.0 g of mono(2-acryloyloxyethyl)succinate, and 0.36 g of polymerization initiator V-601 (trade name, manufactured by FUJIFILM Wako Pure Chemical Corporation) to a 100 mL graduated cylinder and dissolving them in 36.0 g of butyl butyrate.

[0468] 18.0 g of butyl butyrate was added to a 300 mL three-necked flask, and the monomer solution was added dropwise over 2 hours at 80 °C with stirring. After the addition was complete, the temperature was raised to 90 °C and stirred for 2 hours.

[0469] Thus, polymer S-11 (a random copolymer of (meth)acrylic acid polymer) was synthesized, and a dispersion of adhesive S-11 (concentration 40% by mass) was obtained. The average particle size of the adhesive in the dispersion was 140 nm.

[0470] [Synthesis Example T-1: Synthesis of Polymer T-1 and Preparation of Adhesive Solution T-1]

[0471] In Synthesis Example S-1, the amount of V-601 added was changed to 0.12 g. Otherwise, polymer T-1 was synthesized in the same manner as in Synthesis Example S-1, and a solution T-1 of the adhesive composed of the polymer was obtained.

[0472] [Synthesis Example T-2: Synthesis of Polymer T-2 and Preparation of Adhesive Solution T-2]

[0473] In Synthesis Example S-2, the amount of Parroyl IPP added was changed to 0.8 parts by mass. Otherwise, polymer T-2 was synthesized in the same manner as in Synthesis Example S-2, and a solution T-2 of the adhesive composed of the polymer was obtained.

[0474] [Synthetic Example T-3: Synthesis of Polymer T-3 and Preparation of Adhesive Solution T-3]

[0475] In Synthesis Example S-3, the amount of Parroyl IPP added was changed to 0.3 parts by mass. Otherwise, polymer T-3 was synthesized in the same manner as in Synthesis Example S-3, and a solution T-3 of the adhesive composed of the polymer was obtained.

[0476] [Synthetic Example T-4: Synthesis of Polymer T-4 and Preparation of Adhesive Solution T-4]

[0477] In Synthesis Example S-4, the amount of V-601 added was changed to 0.32 g. Otherwise, polymer T-4 was synthesized in the same manner as in Synthesis Example S-4, and a solution T-4 of the adhesive composed of the polymer was obtained.

[0478] [Synthetic Example T-5: Synthesis of Polymer T-5 and Preparation of Adhesive Solution T-5]

[0479] In Synthesis Example S-5, the amount of V-601 added was changed to 1.20 g. Otherwise, polymer T-5 was synthesized in the same manner as in Synthesis Example S-5, and a solution T-5 of the adhesive composed of the polymer was obtained.

[0480] [Synthetic Example T-6: Synthesis of Polymer T-6 and Preparation of Adhesive Solution T-6]

[0481] In Synthesis Example S-6, the amount of V-601 added was changed to 3.30 g. Otherwise, polymer T-6 was synthesized in the same manner as in Synthesis Example S-6, and a solution T-6 of the adhesive composed of the polymer was obtained.

[0482] [Synthetic Example T-7: Synthesis of Polymer T-7 and Preparation of Adhesive Dispersion T-7]

[0483] A monomer solution was prepared by adding 38.8 g of dodecyl acrylate (manufactured by Tokyo Chemical Industry Co., Ltd.), 0.80 g of maleic acid (manufactured by FUJIFILM Wako Pure Chemical Corporation), 0.40 g of poly(ethylene glycol) diacrylate (manufactured by Sigma-Aldrich Co., LLC), and 0.36 g of polymerization initiator V-601 (trade name, manufactured by FUJIFILM Wako Pure Chemical Corporation) to a 100 mL graduated cylinder and dissolving it in 40.0 g of butyl butyrate.

[0484] 20.0 g of butyl butyrate was added to a 300 mL three-necked flask, and the monomer solution was added dropwise over 2 hours at 80 °C with stirring. After the addition was complete, the mixture was stirred at 80 °C for 2 hours, then the temperature was raised to 90 °C and stirred for another 2 hours.

[0485] Thus, polymer T-7 (a crosslinked (meth)acrylic acid polymer of random copolymer) was synthesized. Polymer T-7 is insoluble in butyl butyrate, and a binder composed of polymer T-7 was obtained as a dispersion (40% by mass) of T-7. The average particle size of the binder in this dispersion was 180 nm.

[0486] [Preparation Example T-8: Preparation of Adhesive Solution T-8]

[0487] Polymer T-8 used a polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP polymer, manufactured by Arkema S.A., mass-average molecular weight 100,000). This polymer T-8 was dissolved in butyl butyrate to prepare a 10% by mass adhesive solution T-8.

[0488] The composition, mass-average molecular weight, radius of rotation α, and SP value (MPa) of each polymer synthesized were determined. 1 / 2 The mass-average molecular weight, radius of rotation α, and SP value (MPa) of the polymers are shown in Table 1. 1 / 2 The above methods were used to determine the results.

[0489] Additionally, for polymers S-2, S-3, S-10, T-2, T-3, and T-8, the compounds that constitute the fluorinated polymers are introduced using " / " and listed in the "Composition M1" column. The composition of polymer T-8 is unknown and is indicated by "-" in both the "Content" and "SP Value" columns.

[0490] The "S" and "T" appended to the above polymer No. more specifically indicate the polymer used primarily in the electrode compositions of the examples or comparative examples, and have no further meaning.

[0491] The following shows the synthesized polymers. The content (mass %) of each component is shown in Table 1.

[0492] [Chemical Formula 4]

[0493]

[0494]

[0495] <Abbreviation for table>

[0496] In the table, a "-" in the component column indicates that there is no corresponding component.

[0497] The following describes the compounds that incorporate each constituent component. Additionally, the SP values ​​in the compounds described below are those when they are constituent components (homopolymers).

[0498] -Component M1-

[0499] LA: Dodecyl acrylate (SP value: 18.8 MPa) 1 / 2 , Tokyo Chemical Industry Co., Ltd.)

[0500] EA: Ethyl acrylate (SP value: 20.1 MPa) 1 / 2 , Tokyo Chemical Industry Co., Ltd.)

[0501] LMA: Dodecyl methacrylate (SP value: 18.5 MPa) 1 / 2 , Tokyo Chemical Industry Co., Ltd.)

[0502] VDF: Vinylidene fluoride (SP value: 13.1 MPa) 1 / 2 SynQuest Corporation

[0503] HFP: Hexafluoropropylene (SP value: 9.4 MPa) 1 / 2 SynQuest Corporation

[0504] TFE: Tetrafluoroethylene (SP value: 10.1 MPa) 1 / 2 SynQuest Corporation

[0505] -Component M2-

[0506] Constituent M2 represents a constituent having functional groups with pKa 8 or less.

[0507] Maleic acid: (SP value: 22.2 MPa) 1 / 2 , FUJIFILM Wako Pure Chemical Corporation)

[0508] Monoisopropyl fumarate: (SP value: 20.3 MPa) 1 / 2 , Tokyo Chemical Industry Co., Ltd.)

[0509] 4-Hydroxystyrene: (SP value: 21.9 MPa) 1 / 2 , Tokyo Chemical Industry Co., Ltd.)

[0510] MAEHP: Mono-2-(methacryloyloxy)ethyl phthalate (SP value: 21.4 MPa) 1 / 2 , Tokyo Chemical Industry Co., Ltd.)

[0511] AEHS: Mono(2-Acryloyloxyethyl) Succinate (SP value: 21.8 MPa) 1 / 2 , Tokyo Chemical Industry Co., Ltd.)

[0512] -Component M3-

[0513] Component M3 represents a component that does not correspond to either component M1 or M2.

[0514] HEA: Hydroxyethyl acrylate (SP value: 25.9 MPa) 1 / 2 , Tokyo Chemical Industry Co., Ltd.)

[0515] PEGDA700: Poly(ethylene glycol) diacrylate (number average molecular weight 700, SP value: 21.7 MPa) 1 / 2 (Made by Aldrich, CO.LTD.)

[0516] 2. Synthesis of sulfide-based inorganic solid electrolytes

[0517] [Synthetic Example L-1: Median Radius D] S1-50 Synthesis of LPS1, an inorganic solid electrolyte at 60 nm

[0518] The sulfide-based inorganic solid electrolyte was synthesized with reference to non-patent literature, T. Ohtomo, A. Hayashi, M. Tatsumisago, Y. Tsuchida, S. Hama, K. Kawamoto, Journal of Power Sources, 233, (2013), pp231-235 and A. Hayashi, S. Hama, H. Morimoto, M. Tatsumisago, T. Minami, Chem. Lett., (2001), pp872-873.

[0519] Specifically, 2.42 g of lithium sulfide (Li₂S, manufactured by Aldrich, Inc., purity > 99.98%) and 3.90 g of phosphorus pentasulfide (P₂S₅, manufactured by Aldrich, Inc., purity > 99%) were weighed out in a glove box under an argon atmosphere (dew point -70°C) and placed into an agate mortar. The mixture was then mixed for 5 minutes using an agate pestle. The molar ratio of Li₂S to P₂S₅ was set as Li₂S:P₂S₅ = 75:25.

[0520] Next, 66g of 5mm diameter zirconia beads were added to a 45mL zirconia container (manufactured by Fritsch Co., Ltd.), along with the total amount of the aforementioned mixture of lithium sulfide and phosphorus pentasulfide. The container was then completely sealed under argon atmosphere. The container was placed in a planetary ball mill P-7 (trade name, manufactured by Fritsch Co., Ltd.) and mechanically ground at 25°C and 700 rpm for 48 hours to obtain 6.20g of a yellow powder sulfide-based inorganic solid electrolyte (Li-PS glass, hereinafter, sometimes labeled LPS).

[0521] This synthesizes the median diameter D. S1-50 LPS1 is an inorganic solid electrolyte with a wavelength of 60 nm.

[0522] [Synthetic Example L-2: Median Radius D] S2-50 Synthesis of LPS2, an inorganic solid electrolyte at 1500 nm

[0523] In Synthesis Example L-1, the median diameter D was synthesized in the same manner as in Synthesis Example L-1, except that the mechanical grinding conditions were changed to 700 rpm and 8 hours. S1-50 LPS2 is an inorganic solid electrolyte with a wavelength of 1500 nm.

[0524] [Synthetic Example L-3: Median Radius D] S3-50 Synthesis of LPS3, an inorganic solid electrolyte at 2900 nm

[0525] In Synthesis Example L-1, the median diameter D was synthesized in the same manner as in Synthesis Example L-1, except that the mechanical grinding conditions were changed to a rotation speed of 700 rpm and a grinding time of 4 hours. S1-50 LPS3 is an inorganic solid electrolyte with a wavelength of 2900 nm.

[0526] [Synthetic Example L-4: Median Radius D] S4-50 Synthesis of LPS4, an inorganic solid electrolyte at 4200 nm

[0527] In Synthesis Example L-1, the median diameter D was synthesized in the same manner as in Synthesis Example L-1, except that the mechanical grinding conditions were changed to a rotation speed of 650 rpm and a grinding time of 4 hours. S1-50 The inorganic solid electrolyte LPS4 has a wavelength of 4200 nm.

[0528] 3. NMC: LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 Preparation of O2 (lithium nickel manganese cobalt oxide)

[0529] [Synthetic Example C-1: Median D] AC-50 [Synthesis of 55nm NMC1]

[0530] A 1 mol / L aqueous solution containing nickel sulfate, cobalt sulfate, and manganese sulfate was continuously supplied with sodium hydroxide and ammonia at 60 °C to adjust the pH to 11.3. A metal composite hydroxide with nickel, manganese, and cobalt in a molar ratio of 33:33:33 was prepared by co-precipitation. This metal composite hydroxide and lithium carbonate were weighed to ensure a 1:1 molar ratio of the total moles of metals other than Li (Ni, Co, Mn) to the moles of Li. The mixture was thoroughly mixed, heated at a rate of 5 °C / min, and pre-calcined at 750 °C for 2 hours in air. Then, a formal calcination was performed at 850 °C for 10 hours, with the temperature increased at a rate of 3 °C / min. After cooling to room temperature, a median diameter D was synthesized. AC-50 It is a 55nm NMC1.

[0531] [Synthetic Example C-2: Median Radius D] AC-50 [Synthesis of 140nm NMC2]

[0532] In Synthesis Example C-1, the pre-calcination temperature was set to 800°C and the calcination temperature was set to 830°C. Otherwise, the median diameter D was synthesized in the same manner as in Synthesis Example C-1. AC-50 It is 140nm NMC2.

[0533] [Synthetic Example C-3: Median Radius D] AC-50 Synthesis of 200nm NMC3

[0534] In Synthesis Example C-1, the pre-calcination temperature was set to 820°C and the final calcination temperature was set to 890°C. Otherwise, the median diameter D was synthesized in the same manner as in Synthesis Example C-1. AC-50 It is a 200nm NMC3.

[0535] [Synthetic Example C-4: Median Radius D] AC-50 Synthesis of 1700nm NMC4

[0536] In Synthesis Example C-1, the pre-calcination temperature was set to 900°C and the final calcination temperature was set to 960°C. Otherwise, the median diameter D was synthesized in the same manner as in Synthesis Example C-1. AC-50 It is 1700nm NMC4.

[0537] [Synthetic Example C-5: Median Radius D] AC-50 Synthesis of 2000nm NMC5

[0538] In Synthesis Example C-1, the pre-calcination temperature was set to 930°C and the final calcination temperature was set to 960°C. Otherwise, the median diameter D was synthesized in the same manner as in Synthesis Example C-1. AC-50 It is a 2000nm NMC5.

[0539] [Synthetic Example C-6: Median Radius D] AC-50 Synthesis of 2500nm NMC6

[0540] In Synthesis Example C-1, the pre-calcination temperature was set to 930°C and the final calcination temperature was set to 990°C. Otherwise, the median diameter D was synthesized in the same manner as in Synthesis Example C-1. AC-50 It is NMC6 at 2500nm.

[0541] [Synthetic Example C-7: Median Radius D] AC-50 Synthesis of 2600nm NMC7

[0542] In Synthesis Example C-1, the pre-calcination temperature was set to 960°C and the final calcination temperature was set to 990°C. Otherwise, the median diameter D was synthesized in the same manner as in Synthesis Example C-1. AC-50 It is a 2600nm NMC7.

[0543] [Synthetic Example C-8: Median Radius D] AC-50 Synthesis of 4000nm NMC8

[0544] In Synthesis Example C-1, the pre-calcination temperature was set to 980°C and the final calcination temperature was set to 1040°C. Otherwise, the median diameter D was synthesized in the same manner as in Synthesis Example C-1. AC-50 It is a 4000nm NMC8.

[0545] [Synthetic Example C-9: Median Radius D] AC-50 Synthesis of NMC9 at 4600nm

[0546] In Synthesis Example C-1, the pre-calcination temperature was set to 1000℃ and the final calcination temperature was set to 1080℃. Otherwise, the median diameter D was synthesized in the same manner as in Synthesis Example C-1. AC-50 It is NMC9 with a wavelength of 4600nm.

[0547] [Synthetic Example C-10: Median Radius D] AC-50 Synthesis of 5000nm NMC10

[0548] In Synthesis Example C-1, the pre-calcination temperature was set to 1040℃ and the final calcination temperature was set to 1120℃. Otherwise, the median diameter D was synthesized in the same manner as in Synthesis Example C-1. AC-50 It is NMC10 with a wavelength of 5000nm.

[0549] [Synthetic Example C-11: Median D] AC-50 Synthesis of NMC11 at 5300nm

[0550] In Synthesis Example C-1, the pre-calcination temperature was set to 1080℃ and the final calcination temperature was set to 1150℃. Otherwise, the median diameter D was synthesized in the same manner as in Synthesis Example C-1. AC-50 It is NMC11 with a wavelength of 5300nm.

[0551] 4. Preparation of Silicon (Si)

[0552] Silicon 1: Median diameter D AA-50 =55nm (manufactured by Aldrich, CO.LTD.)

[0553] Silicon 2: Median diameter D AA-50 =200nm (Silgrain MicronCut, manufactured by Elkem Japan)

[0554] Silicon 3: Median diameter D AA-50 =350nm (Silgrain MicronCut, manufactured by Elkem Japan)

[0555] Silicon 4: Median diameter D AA-50 =2000nm (manufactured by Japan Natural Energy & Resources Co., Ltd.)

[0556] Silicon 5: Median diameter D AA-50 =2400nm (manufactured by Japan Natural Energy & Resources Co., Ltd.)

[0557] Silicon 6: Median diameter D AA-50 =2800nm ​​(manufactured by Japan Natural Energy & Resources Co., Ltd.)

[0558] Silicon 7: Median diameter D AA-50 =3000nm (manufactured by Japan Natural Energy & Resources Co., Ltd.)

[0559] Silicon 8: Median diameter D AA-50 =4000nm (manufactured by Japan Natural Energy & Resources Co., Ltd.)

[0560] Silicon 9: Median diameter D AA-50 = 5000nm (IPROS CORPORATION)

[0561] Silicon 10: Median diameter D AA-50=5300nm (manufactured by Japan Natural Energy & Resources Co., Ltd.)

[0562] [Example 1]

[0563] The compositions shown in Tables 2-1 to 2-4 (collectively referred to as Table 2) were prepared as follows.

[0564] <Preparation of the positive electrode composition>

[0565] 60 g of zirconia beads with a diameter of 5 mm were added to a 45 mL zirconium oxide container (manufactured by Fritsch Co., Ltd.), along with 10.2 g of LPS as shown in the "Inorganic Solid Electrolyte" column of Table 2-1 in the above synthesis examples L, and 13 g (total) of butyl butyrate as the dispersion medium. The container was placed in a Fritsch Co., Ltd. planetary ball mill P-7 (trade name) and stirred at 25°C and 200 rpm for 30 minutes. Then, 25.9 g of NMC, the positive electrode active material shown in the "Positive Electrode Active Material" column of Table 2-2, 0.74 g of acetylene black (AB), the conductive additive, and 0.19 g of binder solution or dispersion shown in the "Binder Solution or Dispersion" column of Table 2-1 (mass of solid components) were added to the container. The container was placed in a planetary ball mill P-7 and mixed for 30 minutes at a temperature of 25°C and a speed of 200 rpm to prepare positive electrode compositions (slurries) PK-1 to PK-14 and PKc21 to PKc31, respectively.

[0566] <Preparation of the negative electrode composition>

[0567] 60 g of 5 mm diameter zirconia beads were added to a 45 mL zirconia container (manufactured by Fritsch Co., Ltd.), along with 11.4 g of LPS (shown in the "Inorganic Solid Electrolyte" column of Table 2-3), 0.13 g of binder solution or dispersion (shown in the "Binder Solution or Dispersion" column of Table 2-3) (mass of solid components), and 25.0 g of butyl butyrate (total). The container was placed in a Fritsch Co., Ltd. P-7 planetary ball mill (trade name) and mixed for 60 minutes at 25 °C and 300 rpm. Then, add 12.5g of silicon (Si) as the negative electrode active material and 1.0g of VGCF (made by SHOWA DENKO KK) as the conductive additive, as shown in the "Negative Electrode Active Material" column of Table 2-4. Similarly, place the container in a planetary ball mill P-7 and mix for 10 minutes at a temperature of 25°C and a speed of 100 rpm to prepare negative electrode compositions (slurries) NK-1 to NK-17 and NKc21 to NKc31, respectively.

[0568] For each of the prepared compositions, the viscosity (cP), the median diameter D of the inorganic solid electrolyte, and the active material were considered. S-50 (nm) and D A-50 (nm), and the mass-average molecular weight, radius of gyration α, and SP value (MPa) of the polymer forming the adhesive. 1 / 2 Adsorption rate A of active substances AM The percentages (%) and pKa of functional groups are shown in Table 2. Furthermore, the median diameter D of the inorganic solid electrolyte and active substances contained in each composition was calculated using the above method. 50 This is shown in Table 2 under “D”. 50 "Column (units omitted in the table). In addition, the SP values ​​of each polymer and the dispersion medium were calculated separately (SP value of butyl butyrate: 18.6 MPa)." 1 / 2 The difference (absolute value) and pKa are shown in the "SP value difference" column and "pKa" column of Table 2.

[0569] The viscosity (cP), median diameter (nm), mass-average molecular weight, radius of gyration α, and SP value (MPa) of the composition were determined or calculated using the methods described above. 1 / 2 The adsorption rate A of the active substance was determined by the following method. AM (%) (Units omitted in the table).

[0570] In Table 2, the composition content is the content relative to the total mass of the composition (mass%), and the solid component content is the content relative to 100% by mass of the solid component of the composition (mass%). Units are omitted in the table. Furthermore, the SP values ​​and SP value differences shown in Table 2 are in MPa.1 / 2 The adsorption rate is expressed in terms of mass%, but this is omitted from Table 2.

[0571] In addition, in each composition, the polymer binder composed of polymers S-1 to S-10, T-1 to T-6 and T-8 is dissolved in the dispersion medium, and the binder composed of polymers S-11 and T-7 is dispersed in the dispersion medium in the form of particles.

[0572] [Adsorption rate A of adhesive for active substances] AM [Determination]

[0573] The adsorption rate A was determined using the active material, polymer binder, and dispersion medium used to prepare the electrode compositions shown in Table 2. AM .

[0574] Specifically, a 1% by mass adhesive solution was prepared by dissolving the polymer binder in a dispersion medium (butyl butyrate). Additionally, a 1% by mass adhesive dispersion was prepared for polymers S-11 and T-7. The adhesive solution or dispersion and the active material were placed in a 15 mL vial at a mass ratio of 42:1. The mixture was stirred at 80 rpm for 1 hour at room temperature using a mixing rotor and then allowed to stand. The supernatant obtained from solid-liquid separation was filtered through a 1 μm filter. The filtrate was completely dried, and the mass of the polymer binder remaining in the filtrate (the mass of polymer binder not adsorbed onto the active material) W was measured. A The mass W A and the mass W of the polymer adhesive contained in the adhesive solution used for the determination B The adsorption rate A of the polymer adhesive relative to the active material can be calculated using the following formula. AM (quality%).

[0575] Adsorption rate A of polymer adhesive AM Let denoted as the average adsorption rate obtained by performing the above measurement twice.

[0576] Adsorption rate A AM (%) = [(W) B -W A ) / W B ]×100

[0577] In addition, the adsorption rate A was determined using active material removed from the film-forming active material layer, polymer binder, and dispersion medium used to prepare the electrode composition. AM The result was the same.

[0578]

[0579]

[0580]

[0581]

[0582] <Abbreviation for table>

[0583] LPS1~LPS4: LPS1~LPS4 synthesized in synthesis examples L-1~L-4

[0584] NMC1~NMC11: NMC1~NMC11 synthesized in synthesis examples C-1~C-10

[0585] Si1~Si10: Silicon 1~Silicon 10 prepared as above

[0586] AB: Acetylene Black

[0587] VGCF: Carbon Nanotubes

[0588] <Fabrication of Positive Electrode Sheets for All-Solid-State Secondary Batteries>

[0589] Using a baking applicator (trade name: SA-201, manufactured by TESTER SANGYO CO,.LTD.), the positive electrode compositions shown in the "Electrode Composition No." column of Table 3 obtained above were coated onto aluminum foil with a thickness of 20 μm. The coatings were heated at 80°C for 1 hour, then further heated at 110°C for 1 hour, and dried (to remove the dispersion medium). Then, using a hot press, the dried positive electrode compositions were pressurized at 25°C (10 MPa, 1 minute) to produce positive electrode sheets (labeled as positive electrode sheets in Table 3) 101–114 and c11–c21 for all-solid-state secondary batteries, each having a positive electrode active material layer with a film thickness of 120 μm.

[0590] <Fabrication of negative electrode sheets for all-solid-state secondary batteries>

[0591] Using a baking applicator (trade name: SA-201), the negative electrode compositions shown in the "Electrode Composition No." column of Table 3 obtained above were coated onto copper foil with a thickness of 20 μm. The coatings were heated at 80°C for 1 hour, then further heated at 110°C for 1 hour, and dried (to remove the dispersion medium). Then, using a hot press, the dried negative electrode compositions were pressurized at 25°C (10 MPa, 1 minute) to produce negative electrode sheets (labeled as negative electrode sheets in Table 3) 115–131 and c22–c32 for all-solid-state secondary batteries, each having a negative electrode active material layer with a film thickness of 110 μm.

[0592] <Evaluation 1: Coating Inhomogeneity Test>

[0593] After peeling the active material layer of each positive electrode sheet and each negative electrode sheet (50mm long × 20mm wide) for all-solid-state secondary batteries from the substrate (aluminum foil or copper foil), a test piece 10mm long × 10mm wide is cut from approximately the center of the width of the active material layer. Furthermore, the longitudinal position of the cut test piece TP is set to avoid the same position at both ends of the longitudinal direction within each active material layer. For this test piece TP, the layer thickness is measured at 5 points using a constant voltage thickness gauge (manufactured by TECLOCK Co., Ltd.), and the arithmetic mean Y of the layer thickness is calculated.

[0594] Based on the measured values ​​and their arithmetic mean Y, the larger deviation value (maximum deviation value) obtained using formula (a) or (b) below was applied to the following evaluation criteria to evaluate the occurrence of coating unevenness. In this test, the smaller the maximum deviation value (%), the more uniform the thickness of the active material layer, i.e., the ability to suppress the occurrence of coating unevenness in the electrode composition. In this test, an evaluation criterion of "D" or above is considered acceptable.

[0595] Equation (a): 100 × (maximum value of layer thickness at 5 points - arithmetic mean Y) / (arithmetic mean Y)

[0596] Equation (b): 100 × (arithmetic mean Y - minimum of the layer thicknesses at 5 points) / (arithmetic mean Y)

[0597] For each test piece TP, the layer thickness is measured at the following 5 points: A to E.

[0598] First, such as Figure 4 As shown, draw three virtual lines y1, y2 and y3 that divide the longitudinal direction of the test piece TP into four equal parts. Then, similarly draw three virtual lines x1, x2 and x3 that divide the transverse direction of the test piece TP into four equal parts, thus dividing the surface of the test piece TP into a grid pattern.

[0599] The measurement points are set as the intersection points A of virtual lines x1 and y1, B of virtual lines x1 and y3, C of virtual lines x2 and y2, D of virtual lines x3 and y1, and E of virtual lines x3 and y3.

[0600] -Evaluation Criteria-

[0601] A: Maximum deviation < 1%

[0602] B: 1% ≤ maximum deviation < 3%

[0603] C: 3% ≤ Maximum deviation < 5%

[0604] D: 5% ≤ Maximum deviation < 10%

[0605] E: 10% ≤ maximum deviation < 20%

[0606] F: 20% ≤ Maximum deviation value

[0607] <Evaluation 2: Liquid Drop Test (Shape Maintenance Properties)>

[0608] For each active material layer remaining after cutting out the test piece TP used for layer thickness measurement in the above <Evaluation 1: Coating Inhomogeneity Test>, the layer thicknesses X1 and X2 were measured using a constant pressure thickness gauge (manufactured by TECLOCK Co., Ltd.) at two points 2 mm inside each of the two ends of the active material layer in the width direction, perpendicular to those ends. Furthermore, in each active material layer, the longitudinal positions of the measurement points were set to avoid the same position at both ends in the longitudinal direction.

[0609] The thickness ratios (X1 / Y and X2 / Y) of layer thickness X1 or X2 relative to the "arithmetic mean of layer thickness Y" in the above <Evaluation 1: Coating Inhomogeneity Test> were calculated, and their average value (X / Y) was applied to the following evaluation criteria to evaluate the generation of liquid dripping. In this test, the smaller the average thickness ratio, the more uniform the thickness of the active material layer, i.e., the better the generation of liquid dripping from the electrode composition can be suppressed. In this test, an evaluation criterion of "D" or above is considered acceptable.

[0610] -Evaluation Criteria-

[0611] A: 0.95 ≤ average thickness ratio (X / Y)

[0612] B: 0.90 ≤ average thickness ratio (X / Y) < 0.95

[0613] C: 0.85 ≤ average thickness ratio (X / Y) < 0.90

[0614] D: 0.80 ≤ average thickness ratio (X / Y) < 0.85

[0615] E: 0.70 ≤ average thickness ratio (X / Y) < 0.80

[0616] F: Average thickness ratio (X / Y) < 0.70

[0617] [Table 3]

[0618]

[0619] <Manufacturing of All-Solid-State Secondary Batteries>

[0620] First, positive electrode sheets with solid electrolyte layers for all-solid-state secondary batteries and negative electrode sheets with solid electrolyte layers for all-solid-state secondary batteries were manufactured.

[0621] - Fabrication of positive electrode sheets for all-solid-state secondary batteries with a solid electrolyte layer-

[0622] All-solid-state secondary battery solid electrolyte sheets K-1, manufactured by the following method, were laminated onto the positive active material layer of each all-solid-state secondary battery positive electrode sheet shown in the "Electrode Active Material Layer (Sheet No.)" column of Table 4, with the solid electrolyte layer in contact with the positive active material layer. After being pressurized at 25°C and 50MPa and transferred (laminated) using a press, they were pressurized at 25°C and 600MPa to produce all-solid-state secondary battery positive electrode sheets 101 to 114 and c11 to c21 with a solid electrolyte layer of 30μm thickness (positive active material layer of 90μm thickness).

[0623] - Fabrication of negative electrode sheets for all-solid-state secondary batteries with a solid electrolyte layer-

[0624] By having the solid electrolyte layer in contact with the negative electrode active material layer, solid electrolyte sheets K-1 for all-solid-state secondary batteries, which were fabricated by the following method, were laminated on the negative electrode active material layer of each all-solid-state secondary battery negative electrode sheet shown in the "Electrode Active Material Layer (Sheet No.)" column of Table 4. After being pressurized at 50 MPa at 25°C and transferred (laminated) using a press, they were pressurized at 600 MPa at 25°C. As a result, all-solid-state secondary battery negative electrode sheets 115 to 131 and c22 to c32 with a solid electrolyte layer of 30 μm thickness (negative electrode active material layer of 80 μm thickness) were fabricated.

[0625] The solid electrolyte sheet K-1 for all-solid-state secondary batteries, used for manufacturing electrode sheets for all-solid-state secondary batteries, was prepared as follows.

[0626] -Preparation of composition K-1 containing inorganic solid electrolyte-

[0627] 60 g of 5 mm diameter zirconia beads were added to a 45 mL zirconia container (manufactured by Fritsch Co., Ltd.), along with 8.4 g of LPS synthesized in Synthesis Example L-2 above, 0.6 g of KYNAR FLEX 2500-20 (trade name, PVdF-HFP: polyvinylidene fluoride hexafluoropropylene copolymer, manufactured by ARKEMA) (solid content mass), and 11 g of butyl butyrate as a dispersion medium. The container was then placed in a Fritsch Co., Ltd. planetary ball mill P-7 (trade name). Mixing was performed at 25 °C and 150 rpm for 10 minutes to prepare a composition (slurry) K-1 containing inorganic solid electrolytes.

[0628] -Fabrication of K-1 solid electrolyte sheet for all-solid-state secondary batteries-

[0629] Using a baking applicator (trade name: SA-201, manufactured by TESTER SANGYO CO,.LTD.), the above-obtained composition containing inorganic solid electrolyte was coated onto an aluminum foil with a thickness of 20 μm. The coating was heated at 80°C for 2 hours and then dried (to remove the dispersion medium). Then, using a hot press, the dried composition containing inorganic solid electrolyte was heated and pressurized for 10 seconds at 120°C and 40 MPa to produce solid electrolyte sheets K-1 for all-solid-state secondary batteries. The thickness of the solid electrolyte layer was 50 μm.

[0630] -Manufacturing of all-solid-state secondary batteries-

[0631] Next, a device with Figure 1 The layered structure shown is No. 101, an all-solid-state secondary battery.

[0632] The positive electrode sheet No. 101 (aluminum foil containing solid electrolyte sheet K-1 that has been peeled off) of the all-solid-state secondary battery with the solid electrolyte layer obtained above is cut into a circular plate with a diameter of 14.5 mm, and as shown in the figure. Figure 2 The assembly shown includes spacers and gaskets (in...) Figure 2 In a stainless steel 2032-type button battery case 11 (not shown), lithium foil cut into disc shapes with a diameter of 15 mm is layered on a solid electrolyte layer. After further layering stainless steel foil on top, the 2032-type button battery case 11 is riveted together, thereby manufacturing a [missing information - likely a battery type]. Figure 2 The all-solid-state secondary battery 13 shown is No. 101.

[0633] All-solid-state secondary batteries manufactured in this way have Figure 1 The layer structure shown (where the lithium foil corresponds to the negative electrode active material layer 2 and the negative electrode current collector 1).

[0634] In the manufacture of the aforementioned all-solid-state secondary battery No. 101, the all-solid-state secondary battery positive electrode sheet with a solid electrolyte layer, indicated by No. in the "Electrode Active Material Layer (Sheet No.)" column of Table 4, was used instead of the all-solid-state secondary battery positive electrode sheet No. 101 with a solid electrolyte layer. Otherwise, all-solid-state secondary batteries No. 102 to 114 and c101 to c111 were manufactured in the same manner as the manufacture of all-solid-state secondary battery No. 101.

[0635] Furthermore, the following were manufactured with Figure 1 The layered structure shown is that of the all-solid-state secondary battery No. 115.

[0636] The negative electrode sheet No. 115 (aluminum foil containing the solid electrolyte sheet K-1, which has been peeled off) for an all-solid-state secondary battery with the solid electrolyte obtained above is cut into circular plates with a diameter of 14.5 mm, and as follows: Figure 2 The assembly shown includes spacers and gaskets (in...) Figure 2 In a stainless steel 2032-type button cell battery case 11 (not shown), a positive electrode sheet (positive active material layer) cut to a diameter of 14.0 mm from the positive electrode sheet for all-solid-state secondary batteries (prepared as described below) is stacked on a solid electrolyte layer. A stainless steel foil (positive current collector) is then stacked on top to form an all-solid-state secondary battery laminate 12 (a laminate composed of stainless steel foil, aluminum foil, positive active material layer, solid electrolyte layer, negative active material layer, and copper foil). The 2032-type button cell battery case 11 is then pressed together, thereby manufacturing a... Figure 2 The all-solid-state secondary battery shown is No. 115.

[0637] A positive electrode sheet for all-solid-state secondary batteries, No. 115, was prepared.

[0638] -Preparation of the positive electrode composition-

[0639] 180 zirconia beads with a diameter of 5 mm were added to a 45 mL container (manufactured by Fritsch Co., Ltd.), along with 2.7 g of LPS2 synthesized in Synthesis Example L-2 above, 0.3 g of KYNAR FLEX 2500-20 (trade name, PVdF-HFP: polyvinylidene fluoride hexafluoropropylene copolymer, manufactured by ARKEMA), and 22 g of butyl butyrate. The container was placed in a Fritsch Co., Ltd. planetary ball mill P-7 (trade name) and stirred at 25°C and 300 rpm for 60 minutes. Then, 7.0 g of LiNi was added as the positive electrode active material. 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (NMC) was assembled in the same manner in a planetary ball mill P-7 and mixed for 5 minutes at 25°C and 100 rpm to prepare positive electrode compositions.

[0640] -Fabrication of positive electrode plates for all-solid-state secondary batteries-

[0641] Using a baking applicator (product name: SA-201, manufactured by TESTER SANGYO CO., LTD.), the positive electrode composition obtained above was coated on an aluminum foil (positive electrode current collector) with a thickness of 20 μm, heated at 100 °C for 2 hours, and the positive electrode composition was dried (the dispersion medium was removed). Then, using a hot press, the dried positive electrode composition was pressed at 25 °C (10 MPa, 1 minute) to fabricate a positive electrode sheet for an all-solid-state secondary battery having a positive electrode active material layer with a film thickness of 80 μm.

[0642] In the manufacture of the above all-solid-state secondary battery No. 115, instead of using the negative electrode sheet No. 115 for an all-solid-state secondary battery having a solid electrolyte layer, a negative electrode sheet for an all-solid-state secondary battery having a solid electrolyte layer and indicated by the No. shown in the "electrode active material layer (sheet No.)" column of Table 4 was used. Except for this, all-solid-state secondary batteries No. 116 to 131 and c112 to c122 were manufactured in the same manner as the manufacture of all-solid-state secondary battery No. 115.

[0643] <Evaluation 3: Measurement of ionic conductivity>

[0644] The ionic conductivities of the manufactured all-solid-state secondary batteries were measured. Specifically, for each all-solid-state secondary battery, in a constant temperature bath at 25 °C, using a 1255B FREQUENCY RESPONSE ANALYZER (product name, manufactured by SOLARTRON), the AC impedance was measured up to a voltage amplitude of 5 mV and a frequency range of 1 MHz to 1 Hz. From this, the resistance in the layer thickness direction of the sample for ionic conductivity measurement was obtained, and the ionic conductivity was calculated by the following formula (1).

[0645] Formula (1): Ionic conductivity σ (mS / cm) =

[0646] 1000 × sample layer thickness (cm) / [resistance (Ω) × sample area (cm 2 )]

[0647] In formula (1), the sample layer thickness was measured before putting the laminate 12 into the 2032-type button cell 11 and the value obtained by subtracting the thickness of the current collector (the total layer thickness of the solid electrolyte layer and the electrode active material layer) was used. The sample area was the area of a circular plate-shaped sheet with a diameter of 14.5 mm.

[0648] It was determined whether the obtained ionic conductivity σ was included in any of the following evaluation criteria.

[0649] In the ionic conductivity σ in this experiment, being above the evaluation criterion "D" was considered qualified.

[0650] -Evaluation criteria-

[0651] A: 0.60≤σ

[0652] B: 0.50 ≤ σ < 0.60

[0653] C: 0.40 ≤ σ < 0.50

[0654] D: 0.30 ≤ σ < 0.40

[0655] E: 0.20 ≤ σ < 0.30

[0656] F: σ < 0.20

[0657] [Table 4]

[0658]

[0659] The following information can be obtained from the results shown in Tables 3 and 4.

[0660] The comparative example electrode compositions PKc21-PKc31 and NKc21-NKc31, which do not satisfy the above-described relationships specified in this invention, cannot achieve the purpose of suppressing uneven coating, suppressing liquid dripping, and thus improving the ion conductivity of the all-solid-state secondary battery. This is also true for the comparative example electrode compositions PKc29, PKc31, NKc29, and NKc31, which contain a polymer binder composed of crosslinked polymer T-7.

[0661] In contrast, the electrode compositions PK-1 to PK-14 and NK-1 to NK-17 of the present invention, which contain the polymer binder specified in the present invention and thus satisfy the above-mentioned relationships specified in the present invention, can suppress coating unevenness and liquid dripping even when applied to the film-forming method, and can form an active material layer of a specified shape with uniform thickness. By using these electrode compositions to form the active material layer of an all-solid-state secondary battery, high ionic conductivity (low resistance) can be achieved for the obtained all-solid-state secondary battery. From these results, it can be seen that even by increasing the solid component concentration of the electrode composition of the present invention and increasing the coating amount of the electrode composition of the present invention, coating unevenness and liquid dripping can be suppressed, and an active material layer with high ionic conductivity can be formed.

[0662] The invention has been described together with its embodiments, but unless otherwise specified, the invention is not limited in any detail of the description and should be interpreted broadly without departing from the spirit and scope of the invention as shown in the claims.

[0663] This application claims priority based on Japanese Patent Application 2020-177998, filed on October 23, 2020, the contents of which are incorporated herein by reference and are part of the description herein.

[0664] Symbol Explanation

[0665] 1-Negative electrode current collector, 2-Negative electrode active material layer, 3-Solid electrolyte layer, 4-Positive electrode active material layer, 5-Positive electrode current collector, 6-Working part, 10-All-solid-state secondary battery, 11-Type 2032 button cell battery box, 12-Laminated body for all-solid-state secondary battery, 13-Button type all-solid-state secondary battery, TP-Test piece.

Claims

1. An electrode composition comprising: an inorganic solid electrolyte having conductive ions of metals belonging to Group 1 or Group 2 of the periodic table, an active material, a polymer binder, and a dispersion medium. in, The polymer adhesive is composed of linear polymers. The following radii of rotation α and the following median diameter D 50 With the rotation radius α as the x-axis and the median diameter D as the x-axis... 50 In an orthogonal coordinate system with the y-axis, the region lies within a polygon with vertices A (50, 60), B (178, 4600), C (85, 4600), D (12, 2000), and E (12, 60), where the region includes the boundary line. The radius of rotation α is the radius of rotation of the polymer adhesive in the dispersion medium. The median diameter D 50 The median diameter is obtained by converting the inorganic solid electrolyte and the active substance into their respective median diameters based on their content.

2. The electrode composition according to claim 1, wherein, The SP value of the linear polymer is 16-20 MPa. 1 / 2 .

3. The electrode composition according to claim 1 or 2, wherein, The polymer adhesive has an adsorption rate of less than 40% for the active substance in the dispersion medium.

4. The electrode composition according to claim 1 or 2, wherein, The linear polymer comprises components having functional groups having a pKa of less than 8.

5. The electrode composition according to claim 1 or 2, wherein, The polymer adhesive is dissolved in the dispersion medium.

6. The electrode composition according to claim 1 or 2, wherein, The active material has silicon as a constituent element.

7. The electrode composition according to claim 1 or 2, wherein, The inorganic solid electrolyte is a sulfide-based inorganic solid electrolyte.

8. The electrode composition according to claim 1 or 2, wherein, The SP value of the dispersion medium is 14–24 MPa. 1 / 2 .

9. An electrode sheet for an all-solid-state secondary battery, having a layer on the surface of a substrate composed of the electrode composition according to any one of claims 1 to 8.

10. An all-solid-state secondary battery, comprising sequentially a positive electrode active material layer, a solid electrolyte layer, and a negative electrode active material layer. At least one of the positive electrode active material layer and the negative electrode active material layer is a layer composed of the electrode composition according to any one of claims 1 to 8.

11. A method for manufacturing an electrode sheet for an all-solid-state secondary battery, wherein, The electrode composition of any one of claims 1 to 8 is formed on the surface of a substrate.

12. A method for manufacturing an all-solid-state secondary battery, wherein the all-solid-state secondary battery is manufactured by the manufacturing method of claim 11.

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