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

Abstract

The present invention provides: an electrode composition which contains an inorganic solid electrolyte, an active material, a polymer binder that is configured to contain a linear polymer, and a dispersion medium, wherein the radius α of gyration of the polymer binder and the equivalent median diameter D50 of the inorganic solid electrolyte and the active material are inside (including the boundary line) of a polygonal region with vertices at points A to E in a rectangular coordinate system wherein the radius α of gyration is taken on the x-axis and the median diameter D50 is taken on the y-axis; an electrode sheet for all-solid-state secondary batteries and an all-solid-state secondary battery, each of which uses this electrode composition; a method for producing an electrode sheet for all-solid-state secondary batteries; and a method for producing an all-solid-state secondary battery.

Description

[Technical Field]

[0001] The present invention relates to an electrode composition, an electrode sheet for an all-solid-state secondary battery, an all-solid-state secondary battery, and a method for manufacturing the electrode sheet for an all-solid-state secondary battery and the all-solid-state secondary battery. [Background technology]

[0002] All-solid-state secondary batteries, in which the negative electrode, electrolyte, and positive electrode are all solid, can significantly improve the safety and reliability that are issues with secondary batteries that use organic electrolytes. It is also believed that they can achieve longer life. Furthermore, all-solid-state secondary batteries can be configured with electrodes and electrolytes directly arranged in series. This allows for higher energy density than secondary batteries that use organic electrolytes, and they are expected to be used in electric vehicles, large-scale storage batteries, and other applications.

[0003] In such all-solid-state secondary batteries, materials forming constituent layers (such as a solid electrolyte layer, a negative electrode active material layer, and a positive electrode active material layer) include active materials such as inorganic solid electrolytes, negative electrode active materials, and positive electrode active materials. Among these, inorganic solid electrolytes, particularly oxide-based inorganic solid electrolytes and sulfide-based inorganic solid electrolytes, have recently been expected as electrolyte materials with high ionic conductivity approaching that of organic electrolyte solutions. Therefore, in order to achieve high ionic conductivity, which is a basic performance requirement of all-solid-state secondary batteries, materials containing the above-mentioned inorganic solid electrolyte and active material have been proposed as materials for forming negative electrode active material layers or positive electrode active material layers. For example, Patent Document 1 describes a "slurry containing a solid electrolyte and a specific polymer," in which the "specific polymer" is a hydrogenated block copolymer obtained by hydrogenating a linear or branched block copolymer comprising (A) a block made of polybutadiene having a 1,2-vinyl bond content of 15% or less, and (B) a block made of a butadiene (co)polymer consisting of 50 to 100% by weight of butadiene and 0 to 50% by weight of other monomers, and wherein the 1,2-vinyl bond content of the butadiene portion is 20 to 90%, and wherein the (A) / (B) ratio is 5 / 95 to 70 / 30% by weight. Furthermore, Patent Document 2 describes a solid electrolyte composition that contains "at least one dendritic polymer selected from the group consisting of dendrons, dendrimers, and hyperbranched polymers, and an inorganic solid electrolyte that has ionic conductivity for a metal belonging to Group 1 or 2 of the periodic table," in which the dendritic polymer has a specific functional group. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 11-086899 [Patent Document 2] International Publication No. 2017 / 018456A1 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the constituent layers composed of solid particles such as inorganic solid electrolytes, active materials, and conductive additives, the state of interfacial contact between the solid particles is restricted. Therefore, even if the solid particles themselves forming the constituent layers can exhibit high ionic conductivity, the interfacial resistance of the solid particles increases, reducing the electronic and ionic conductivity, making it impossible to extract (discharge) a large current from the all-solid-state secondary battery.

[0006] When forming an active material layer using a material (also referred to as an electrode material) containing an inorganic solid electrolyte and an active material, conventional electrode materials tend to cause dripping (a phenomenon in which the electrode material flows and the shape of the edges of the coated layer collapses (reduces thickness)) when the electrode material is formed into a film on a substrate. This dripping tends to occur near both widthwise edges of the electrode material applied in sheet form. Increasing the viscosity (concentration) of the electrode material is effective in suppressing this dripping, but this causes coating unevenness (uneven layer thickness) in the coated layer of the electrode material. This coating unevenness tends to occur near the widthwise center of the electrode material applied in sheet form.

[0007] In recent years, development toward the practical application of all-solid-state secondary batteries has progressed rapidly. To address this, improvements are desired in both the battery performance (higher energy density) and industrial manufacturing of all-solid-state secondary batteries. Increasing the active material layer thickness is an effective way to increase the energy density of all-solid-state secondary batteries. This can be achieved, for example, by increasing the amount of electrode material applied or by increasing the solid content concentration. Even when forming thicker active material layers, it would be advantageous from an industrial manufacturing perspective if the electrode material could be formed in a single film formation process. However, conventional electrode materials with increased solid content or high application rates can result in significant dripping or uneven coating. Therefore, it is difficult to obtain a uniformly thick active material layer of a desired shape using film formation methods in which the electrode material is applied and dried on a substrate, especially film formation methods using the roll-to-roll method, which allows for continuous film formation in sheet form and is highly productive.

[0008] As described above, there is a need for an electrode material that can suppress the occurrence of dripping and uneven coating even when applied to a film-forming method, in addition to improving ionic conductivity, which is a basic performance of all-solid-state secondary batteries. However, Patent Documents 1 and 2 do not mention this point of view.

[0009] An object of the present invention is to provide an electrode composition that can form an active material layer that can exhibit high ionic conductivity while suppressing the occurrence of dripping and uneven application during film formation. Another object of the present invention is to provide an electrode sheet for an all-solid-state secondary battery, an all-solid-state secondary battery, and a method for manufacturing the electrode sheet for an all-solid-state secondary battery and the all-solid-state secondary battery, using the electrode composition. [Means for solving the problem]

[0010] The present inventors have conducted studies focusing on the relationship between the inorganic solid electrolyte, active material, and polymer binder used in the electrode composition from the viewpoints of improving the coating properties (dripping and coating unevenness) of the electrode composition and the ability to construct a conductive path formed by solid particles when the electrode composition is used as an active material layer. As a result, the ... 50 It has been found that by setting the radius of rotation α of the polymer binder containing a linear polymer within a specific range described below, it is possible to suppress both dripping of the electrode composition and uneven coating during film formation, and also to establish sufficient ion conduction paths between the solid particles. The present invention was completed through further investigation based on these findings.

[0011] That is, the above problems were solved by the following means. <1> An electrode composition comprising an inorganic solid electrolyte having ion conductivity of a metal belonging to Group 1 or 2 of the periodic table, an active material, a polymer binder, and a dispersion medium, the polymer binder comprises a linear polymer, the radius of rotation α of the polymer binder in the dispersion medium, and the median diameter D of the inorganic solid electrolyte and the active material converted into a content ratio; 50 The radius of rotation α is the x-axis, and the median diameter D 50An electrode composition located within a polygonal area (including the boundary line) with vertices A (50,60), B (178,4600), C (85,4600), D (12,2000), and E (12,60) in a Cartesian coordinate system with y-axis at . <2> SP value of linear polymer is 16-20MPa 1 / 2 That is, <1> The electrode composition according to claim 1. <3> the polymer binder has an adsorption rate of 40% or less for the active material in the dispersion medium; <1> or <2> The electrode composition according to claim 1. <4> The linear polymer contains a component having a functional group with a pKa of 8 or less. <1> ~ <3> 10. An electrode composition according to any one of the preceding claims. <5> The polymer binder is soluble in the dispersion medium. <1> ~ <4> 10. An electrode composition according to any one of the preceding claims. <6> The active material contains silicon as a constituent element. <1> ~ <5> 10. An electrode composition according to any one of the preceding claims. <7> The inorganic solid electrolyte is a sulfide-based inorganic solid electrolyte. <1> ~ <6> 10. An electrode composition according to any one of the preceding claims. <8> Dispersion medium SP value: 14 to 24 MPa 1 / 2 That is, <1> ~ <7> 10. An electrode composition according to any one of the preceding claims. <9> the above <1> ~ <8> 1. An electrode sheet for an all-solid-state secondary battery, comprising a layer made of the electrode composition according to any one of 1 to 3 above on a substrate surface. <10> An all-solid-state secondary battery comprising a positive electrode active material layer, a solid electrolyte layer, and a negative electrode active material layer in this order, At least one of the positive electrode active material layer and the negative electrode active material layer is <1> ~ <8> 1. An all-solid-state secondary battery, wherein the layer is made of the electrode composition according to any one of 1 to 3. <11> the above <1> ~ <8> 1. A method for producing an electrode sheet for an all-solid-state secondary battery, comprising forming a film of the electrode composition according to any one of the above items on a surface of a substrate. <12> the above <11> 2. A method for producing an all-solid-state secondary battery, comprising the steps of: producing an all-solid-state secondary battery through the method for producing an all-solid-state secondary battery according to claim 1 ; [Effects of the Invention]

[0012] The present invention can provide an electrode composition that can form an active material layer that can exhibit high ionic conductivity while suppressing the occurrence of dripping and uneven coating during film formation. The present invention can also provide an electrode sheet for an all-solid-state secondary battery and an all-solid-state secondary battery that have an active material layer composed of this electrode composition. Furthermore, the present invention can provide 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. The above and other features and advantages of the present invention will become more apparent from the following description, taken in conjunction with the accompanying drawings where appropriate. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a longitudinal sectional view schematically showing an all-solid-state secondary battery according to a preferred embodiment of the present invention. [Figure 2] FIG. 2 is a longitudinal sectional view schematically showing a coin-type all-solid-state secondary battery produced in the example. [Figure 3] FIG. 3 is a diagram showing the relationship between the median diameter D50 and the radius of gyration α in the present invention. [Figure 4] FIG. 4 is a diagram illustrating the layer thickness measurement points in the coating unevenness test in the examples. DETAILED DESCRIPTION OF THE INVENTION

[0014] In the present invention, a numerical range expressed using "to" means a range that includes the numerical values ​​written before and after "to" as the lower and upper limits. In the present invention, when multiple numerical ranges are set for the content of a component, physical properties, etc., the upper and lower limits forming the numerical range are not limited to a specific combination of upper and lower limits, and any numerical range can be formed by appropriately combining the upper and lower limits of each numerical range. In the present invention, the expression of a compound (for example, when it is referred to by adding "compound" to the end) is used to mean not only the compound itself, but also its salts and ions. It also means to include derivatives that have been partially modified, such as by introducing a substituent, within the scope that does not impair the effects of the present invention. In the present invention, (meth)acrylic means one or both of acrylic and methacrylic. The same applies to (meth)acrylate. In the present invention, substituents, linking groups, etc. (hereinafter referred to as substituents, etc.) that are not specified as substituted or unsubstituted mean that the group may have an appropriate substituent. Therefore, even when simply described as a YYY group in the present invention, this YYY group includes not only an embodiment in which it has no substituent, but also an embodiment in which it further has a substituent. This also applies to compounds in which it is not specified as substituted or unsubstituted. Preferred substituents include, for example, the substituent Z described below. In the present invention, when there are multiple substituents, etc., designated by a specific symbol, or when multiple substituents, etc., are simultaneously or alternatively specified, it means that the respective substituents, etc., may be the same or different from each other. Furthermore, even if not otherwise specified, when multiple substituents, etc., are adjacent, they may be linked to each other or condensed to form a ring. In the present invention, the term "polymer" refers to a polymer, and is synonymous with the term "polymer compound." The term "polymer binder" (also simply referred to as "binder") refers to a binder made of a polymer, and includes both the polymer itself and a binder made up (formed) containing a polymer.

[0015] In the present invention, a composition containing an inorganic solid electrolyte and an active material and used as a material for forming an 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 a solid electrolyte layer of an all-solid-state secondary battery is referred to as an inorganic solid electrolyte-containing composition, and this composition usually does not contain an active material. In the present invention, the electrode composition includes a positive electrode composition containing a positive electrode active material and a negative electrode composition containing a negative electrode active material. Therefore, either one of the positive electrode composition and the negative electrode composition, or both together, may be simply referred to as an electrode composition. Furthermore, either one of the positive electrode active material layer and the negative electrode active material layer, or both together, may be simply referred to as an active material layer or an electrode active material layer. Furthermore, either one of the positive electrode active material and the negative electrode active material, or both together, may be simply referred to as an active material or an electrode active material.

[0016] [Electrode composition] The electrode composition of the present invention contains an inorganic solid electrolyte having ionic conductivity of a metal belonging to Group 1 or 2 of the periodic table, an active material, a polymer binder, and a dispersion medium. In the electrode composition of the present invention, the radius of gyration α of the polymer binder containing a linear polymer in the dispersion medium and the median diameter D of the inorganic solid electrolyte (particles) and the active material (particles) converted into their respective median diameters in terms of their contents (mass fractions) in the electrode composition are 50 As shown in Figure 3, the radius of rotation α is on the x-axis, and the median diameter D 50 In an orthogonal coordinate system with y as the y-axis, the electrode composition satisfies the relationship that it exists within a pentagonal region (including on the boundary line) having five specific points A to E as vertices, which will be described later. The electrode composition of the present invention that satisfies this relationship can form an active material layer that can exhibit high ionic conductivity while making it possible to suppress the occurrence of dripping and uneven application during film formation. By using this electrode composition as a material for forming an active material layer, it is possible to realize an electrode sheet for an all-solid-state secondary battery having, on the surface of a substrate, an active material layer that is uniform in thickness, has a predetermined shape, and can be appropriately thickened even in a film formation method, and further an all-solid-state secondary battery that exhibits high ionic conductivity (low resistance).

[0017] The details of the reason for this are not yet clear, but it is thought to be as follows. That is, the polymer binder is configured to contain a linear polymer and has a median diameter D 50and the radius of gyration α, in the electrode composition, the surfaces of the solid particles such as the inorganic solid electrolyte and the active material are not excessively coated, and when the active material layer is formed, contact between the solid particles is ensured to form a sufficient conductive path. In addition, the inorganic solid electrolyte, the active material, and the polymer binder have a median diameter D 50 Since the relationship between the radius of gyration α and the size and number (number of molecules per mass content) of the polymer binder relative to the inorganic solid electrolyte and the active material is satisfied, it is possible to set a good balance, thereby improving the dispersibility of the inorganic solid electrolyte and the active material and reducing excessive interactions between the polymer binders. As a result, an excessive increase in viscosity in the electrode composition is suppressed, and a good balance can be achieved between fluidity during application and non-fluidity after application. Thus, the electrode composition of the present invention can suppress the occurrence of dripping and uneven coating during film formation, and can form an active material layer that is uniform in thickness and has a predetermined shape even in the film formation method, and that can exhibit high ionic conductivity. Furthermore, this electrode composition is such that the inorganic solid electrolyte, active material, and polymer binder have a median diameter D 50 and the radius of gyration α, the fluidity at the time of application and the non-fluidity after application can be maintained even if the contents of the inorganic solid electrolyte and active material are increased. Therefore, even if the active material layer is thick, an active material layer having a uniform thickness and a predetermined shape can be formed by a film-forming method such as a highly productive roll-to-roll method.

[0018] The median diameter D that the electrode composition of the present invention should satisfy 50 The relationship between the radius of rotation α and the radius of rotation α will be explained. The radius of rotation α of the polymer binder containing a linear polymer in the dispersion medium contained in the electrode composition means the size of the polymer binder (linear polymer molecule) in this dispersion medium, and the median diameter D 50 means the overall size of the inorganic solid electrolyte and active material in which the polymer binder acts in the electrode composition and the active material layer formed therefrom. In the electrode composition, the radius of gyration α also means the number of polymer binders present per unit mass, and the median diameter D 50It also means the total number of inorganic solid electrolytes and active materials present per unit mass. In the present invention, by satisfying the above relationship, the size of the polymer binder, the size of the inorganic solid electrolyte, and the active material, as well as the number of the polymer binder, the inorganic solid electrolyte, and the active material present per unit mass, are set in a balanced manner, and as described above, it is possible to achieve both high ionic conductivity in the active material layer and fluidity during application and non-fluidity after application of the electrode composition.

[0019] Radius of gyration α and median diameter D 50 In the Cartesian coordinate system shown in Figure 3, the relationship exists within a pentagonal area (including the boundary line) with vertices A (50,60), B (178,4600), C (85,4600), D (12,2000), and E (12,60). The radius of gyration α and median diameter D 50 When the radius of gyration α and the median diameter D are within the above range, an active material layer can be formed that can exhibit high ionic conductivity while suppressing the occurrence of dripping and uneven application of the electrode composition, as described above. 50 If the difference is outside the above range, it is not possible to suppress the occurrence of dripping and uneven application of the electrode composition and improve the ionic conductivity at the same time. A line connecting points A and B (for example, D 50 If the value is inside the above range (including on a straight line; the same applies hereinafter) of α=35α-1700, the effect of improving coating unevenness is particularly excellent, but if it is outside the range, the effect of improving coating unevenness and ion conductivity is inferior. A line connecting points B and C (D 50 When the thickness is within the above range of 0.05 mm / s (=4600), the occurrence of uneven coating and dripping is suppressed, and in particular, the size of the inorganic solid electrolyte and the active material is such that their surfaces are adequately covered with the polymer binder, resulting in an excellent effect of improving ionic conductivity. A straight line connecting points C and D (for example, D 50 If the thickness is inside the above range of α=36α+1600, the effects of improving the liquid dripping and ionic conductivity are particularly excellent, and if it is outside the range, the effects of improving the liquid dripping and ionic conductivity are inferior. When the polymer binder is located inside the above region of the straight line (α=12) connecting points D and E, the size of the polymer binder is large enough to adequately cover the surfaces of the inorganic solid electrolyte and the active material, thereby maintaining the effect of suppressing dripping and uneven coating while particularly enhancing the effect of improving ionic conductivity. A line connecting point E and point A (D 50 = 60), the size of the inorganic solid electrolyte and the active material is such that the surfaces thereof are adequately covered with the polymer binder, and the effect of improving ion conductivity in particular is excellent.

[0020] In the present invention, the radius of rotation α and the median diameter D 50 The region in the orthogonal coordinate system that satisfies the above conditions can be a polygonal region (including a boundary line) in which at least one of the five points is replaced with one or more points other than the five points. Even in this region, it is possible to suppress dripping and uneven coating and improve ionic conductivity. The radius of gyration α and the median diameter D 50 In the Cartesian coordinate system shown in FIG. 3, it is preferable that the point is within a hexagonal area (including the boundary line) with vertices A, F (85,2800), C, G (37,2800), D, and E. The line connecting A and F is, for example, D 50 =78α-3900. Radius of gyration α and median diameter D 50 More preferably, it is within a pentagonal area with vertices A, F, G, D, and E (including on the boundary line), even more preferably within a quadrangular area with vertices A, H (50,2000), D, and E (including on the boundary line), and particularly preferably within a quadrangular area with vertices J (50,900), H, D, and I (12,900) (including on the boundary line).

[0021] Even when the electrode composition contains a positive electrode active material as the active material, the radius of gyration α and the median diameter D 50If the thickness is within the above ranges, an active material layer can be formed that can exhibit high ionic conductivity while suppressing dripping and uneven application of the electrode composition. However, it may also be any of the areas defined below. In the Cartesian coordinate system shown in Figure 3, the radius of gyration α and the median diameter D 50 The point is located within the pentagonal area (including the boundary line) with the vertices AP point (50,120), BP point (172,4500), CP point (85,4500), DP point (16,1600) and EP point (16,120). Here, the line connecting the AP point and the BP point is, for example, D 50 =36α-1700, and the line connecting the CP point and the DP point is, for example, D 50 =42α+930. The significance of the lines connecting two of the five points that define this pentagon is the same as that of points A to E above. This area can also be a polygonal area in which at least one of the five points is replaced with one or more points other than the five points. A preferred region in the Cartesian coordinate system is the hexagonal region (including the boundary line) with the vertices AP, FP (85,2700), CP, GP (37,2600), DP, and EP points as its vertices, because it can achieve a better balance between suppressing dripping and uneven application of the electrode composition and improving ionic conductivity. Here, the line connecting the AP and FP points is, for example, D 50 =74α-3600. In the positive electrode composition, the radius of gyration α and the median diameter D 50 More preferably, it is within a pentagonal area with points AP, FP, GP, DP, and EP as vertices (however, this includes the boundary line), and even more preferably, it is within a polygonal area with points AP, HP (50,1600), DP, and EP as vertices (however, this includes the boundary line).

[0022] The radius of rotation α is not particularly limited as long as it satisfies the above relationship. For example, the radius of rotation α can be set to a value equal to the median diameter D 50With respect to the saturation index, it is preferably 12 or more, more preferably 16 or more, even more preferably 20 or more, and particularly preferably 25 or more. On the other hand, the upper limit is preferably 178 or less, more preferably 172 or less, even more preferably 140 or less, particularly preferably 100 or less, and most preferably 70 or less.

[0023] The radius of gyration α can be measured using the following polymer binder solution: A static light scattering measurement device (DLS-8000, manufactured by Otsuka Electronics Co., Ltd., laser wavelength λ=632.8 nm) was used to measure the scattering intensity I at scattering angles θ=50°, 60°, 70°, 80°, 90°, 100°, 110°, 120°, and 130° for the polymer binder solution (four polymer concentrations, 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 is measured and the excess Rayleigh ratio is calculated using the following formula: The obtained excess Rayleigh ratio R θ A Zimm plot was created based on the following formula (I), and the q 2 The radius of gyration α can be calculated by evaluating the slope of the In the following formula, n and δn / δc are the refractive index and the concentration change rate of the polymer binder solution, respectively, and can be determined using, for example, a differential refractometer (DRM-3000, manufactured by Otsuka Electronics Co., Ltd.). tol and R tol are the refractive index and Rayleigh ratio of toluene, and known values ​​can be found in, for example, literature [1] (ERPike, WRMPomeroy, JMVaughan, J. Chem. Phys., 62 (1975), 3188-3192). q is the scattering vector, and k is an optical constant, each defined by the following equations. M w is the mass average molecular weight of the polymer to be measured, N A is the Avogadro constant. A2 is the second virial coefficient. In this measurement, O(q4 ) and O(c 2 ) is ignored because it results in a small value. The polymer binder solution is prepared by dissolving the polymer to be measured in the dispersion medium (butyl butyrate in this example) used to prepare the electrode composition.

[0024]

number

[0025] The radius of gyration α of the polymer binder can be adjusted as appropriate by the molecular structure (linear) of the polymer (usually a linear polymer) that forms the polymer binder, the mass average molecular weight, the presence or absence of a functional group with a pKa of 8 or less (described later), the content of a component having such a functional group in the polymer, the SP value, etc. For example, to increase the radius of gyration α, the mass average molecular weight can be increased, a functional group with a pKa of 8 or less can be introduced, or the difference between the SP value of the polymer binder and the SP value of the dispersion medium can be set to 2 or less.

[0026] Median diameter D 50 is not particularly limited as long as the above relationship is satisfied. For example, the median diameter D 50 is preferably 60 nm or more, more preferably 300 nm or more, and even more preferably 500 nm or more, relative to the radius of gyration α in the above-mentioned range, while the upper limit thereof 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. Median diameter D 50 is the median diameter D of the inorganic solid electrolyte S-50 and the median diameter D of the active material A-50 and are measured by the methods described below, and the values ​​calculated from the following formula are rounded off to two significant digits. Median diameter D 50 =(D S-50 ×W S )+(D A-50 ×W A ) In the formula, D S-50 is the median diameter of the inorganic solid electrolyte, D A-50 indicates the median diameter of the active material. S and W A indicate the mass fraction of the inorganic solid electrolyte and the mass fraction of the active material, respectively, relative to the total mass of the inorganic solid electrolyte and the active material in the electrode composition.

[0027] The electrode composition of the present invention is preferably a slurry in which the inorganic solid electrolyte and the active material are dispersed in the form of particles in a dispersion medium.

[0028] 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, although there is no particular limitation on whether the polymer binder is adsorbed to the inorganic solid electrolyte, it is preferable that the polymer binder be adsorbed to the active material within a range that satisfies the adsorption rate described below. This allows for enhanced dispersibility without excessively coating the surface of the active material. On the other hand, the polymer binder functions as a binder that binds together solid particles of the active material, inorganic solid electrolyte, and further solid particles of a conductive additive that may coexist in the active material layer. It also functions as a binder that binds together the current collector and the solid particles. In the electrode composition, the polymer binder does not necessarily have the function of binding together solid particles.

[0029] The viscosity (initial viscosity) of the electrode composition of the present invention 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, the viscosity under the following measurement conditions is preferably 300 to 4000 cP, more preferably 800 to 4000 cP, in order to enable excellent coating properties without dripping and uneven coating. - Measurement conditions - Temperature: 23℃ Shear rate: 10 / s Measuring equipment: TV-35 type viscometer (manufactured by Toki Sangyo Co., Ltd.) Measurement method: Drop 1.1 ml of the composition into a sample cup, set the sample cup in a viscometer equipped with a standard cone rotor (1°34' x R24), set the measurement range to "U," rotate at the above shear rate, and read the value after 1 minute.

[0030] The electrode composition of the present invention is preferably a non-aqueous composition. In the present invention, the non-aqueous composition includes not only an embodiment that does not contain water, but also an embodiment in which the water content (also referred to as water content) is preferably 500 ppm or less. In a non-aqueous composition, the water content is more preferably 200 ppm or less, even more preferably 100 ppm or less, and particularly preferably 50 ppm or less. When the electrode composition is a non-aqueous composition, deterioration of the inorganic solid electrolyte can be suppressed. The water content refers to the amount of water contained in the electrode composition (mass ratio relative to the electrode composition), and specifically, is the value measured by filtering through a 0.02 μm membrane filter and using Karl Fischer titration.

[0031] The electrode composition of the present invention can be preferably used as an electrode sheet for an all-solid-state secondary battery or as a material for forming an active material layer of an all-solid-state secondary battery, particularly as a material for forming a negative electrode sheet or a negative electrode active material layer for an all-solid-state secondary battery containing a negative electrode active material that expands and contracts significantly during charging and discharging.

[0032] Components contained in the electrode composition of the present invention and components that can be contained therein will be described below.

[0033] <Inorganic solid electrolyte> The electrode composition of the present invention contains an inorganic solid electrolyte. In the present invention, the term "inorganic solid electrolyte" refers to an inorganic solid electrolyte, and a solid electrolyte is a solid electrolyte capable of transferring ions therein. Because inorganic solid electrolytes do not contain organic substances as the main ion-conducting material, they are clearly distinguished from organic solid electrolytes (polymer electrolytes such as polyethylene oxide (PEO) and organic electrolyte salts such as lithium bis(trifluoromethanesulfonyl)imide (LiTFSI)). Furthermore, inorganic solid electrolytes are solid in a steady state and are not typically dissociated or liberated into cations and anions. In this respect, they are also clearly distinguished from electrolytic solutions or inorganic electrolyte salts (such as LiPF, LiBF, lithium bis(fluorosulfonyl)imide (LiFSI), and LiCl) that are dissociated or liberated into cations and anions in a polymer. The inorganic solid electrolyte is not particularly limited as long as it has ionic conductivity for metals belonging to Group 1 or Group 2 of the periodic table, but generally does not have electronic conductivity. When the all-solid-state secondary battery of the present invention is a lithium-ion battery, the inorganic solid electrolyte preferably has ionic conductivity for lithium ions.

[0034] The inorganic solid electrolyte contained in the electrode composition of the present invention is in the form of particles at least in the electrode composition. The shape of the particles is not particularly limited and may be flat, amorphous, etc., but spherical or granular is preferred. Inorganic solid electrolyte particle size (volume average particle size: median size) D S-50 is the median diameter D 50 As long as the above condition is satisfied, there are no particular limitations and the value can be set appropriately. S-50 is, for example, preferably 0.01 μm or more, more preferably 0.05 μm or more, even more preferably 1.4 μm or more, and particularly preferably 2.7 μm or more. S-50 The upper limit is preferably 4.5 μm or less, more preferably 4.0 μm or less, even more preferably 3.2 μm or less, particularly preferably 2.1 μm or less, and most preferably 1.9 μm or less. The particle size of inorganic solid electrolytes is measured using the following procedure. Inorganic solid electrolyte particles are diluted with water (heptane for substances unstable in water) to prepare a 1% by mass dispersion in a 20 mL sample bottle. The diluted dispersion sample is irradiated with 1 kHz ultrasound for 10 minutes and used for testing immediately thereafter. This dispersion sample is used with a laser diffraction / scattering particle size distribution analyzer LA-920 (trade name, manufactured by HORIBA Corporation) and a quartz measurement cell at a temperature of 25°C, and data is collected 50 times to determine the volume average particle diameter D S-50 For other detailed conditions, refer to the description in Japanese Industrial Standards (JIS) Z 8828:2013 "Particle size analysis - dynamic light scattering method" as necessary. Five samples are prepared for each level, and the average value is used. When the electrode composition contains two or more inorganic solid electrolytes, the practical median diameter D S-50 can also be measured by the above method, but in the present invention, the median diameter is measured for each inorganic solid electrolyte by the above method and calculated from the following formula. Median diameter D S-50 =D S1-50 ×W S1 +D S2-50 ×W S2 +··· In the formula, D S1-50 , D S2-50 ··· indicates the median diameter of the inorganic solid electrolyte, and W S1 , W S2 ··· indicates the mass fraction of the inorganic solid electrolyte relative to the total volume.

[0035] The method for adjusting the average particle size is not particularly limited, and known methods can be applied, such as a method using a conventional pulverizer or classifier. Suitable pulverizers or classifiers include, for example, a mortar, a ball mill, a sand mill, a vibration ball mill, a satellite ball mill, a planetary ball mill, a swirling airflow jet mill, or a sieve. Wet pulverization can be performed in the presence of a dispersion medium such as water or methanol. Classification is preferably performed to obtain the desired particle size. Classification is not particularly limited, and can be performed using a sieve, an air classifier, or the like. Both dry and wet classification methods can be used.

[0036] The inorganic solid electrolyte may be selected from solid electrolyte materials typically used in all-solid-state secondary batteries. Examples of inorganic solid electrolytes include (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. Sulfide-based inorganic solid electrolytes are preferred because they can form a better interface between the active material and the inorganic solid electrolyte.

[0037] (i) Sulfide-based inorganic solid electrolyte The sulfide-based inorganic solid electrolyte preferably contains sulfur atoms, has the ionic conductivity of a metal belonging to Group 1 or 2 of the periodic table, and has electronic insulation. The sulfide-based inorganic solid electrolyte preferably contains at least Li, S, and P as elements and has lithium ion conductivity, but may contain elements other than Li, S, and P as appropriate.

[0038] An example of the sulfide-based inorganic solid electrolyte is a lithium ion conductive inorganic solid electrolyte that satisfies the composition represented by the following formula (S1). L a1 M b1 P c1 S d1 A e1 (S1) In the formula, L represents an element selected from Li, Na, and K, and Li is preferred. M represents an element selected from B, Zn, Sn, Si, Cu, Ga, Sb, Al, and Ge. A represents an element selected from I, Br, Cl, and F. a1 to e1 represent the composition ratio of each element, and a1:b1:c1:d1:e1 satisfies the ratio 1-12:0-5:1:2-12:0-10. a1 is preferably 1-9, and more preferably 1.5-7.5. b1 is preferably 0-3, and more preferably 0-1. d1 is preferably 2.5-10, and more preferably 3.0-8.5. e1 is preferably 0-5, and more preferably 0-3.

[0039] The composition ratio of each element can be controlled by adjusting the blending amounts of raw material compounds when producing the sulfide-based inorganic solid electrolyte, as described below.

[0040] The sulfide-based inorganic solid electrolyte may be amorphous (glass) or crystallized (glass-ceramic), or may be only partially crystallized. For example, a Li-PS-based glass containing Li, P, and S, or a Li-PS-based glass-ceramic containing Li, P, and S may be used. The sulfide-based inorganic solid electrolyte can be produced by reacting at least two or more raw materials selected from the group consisting of lithium sulfide (LiS), phosphorus sulfide (e.g., diphosphorus pentasulfide (PS)), elemental phosphorus, elemental sulfur, sodium sulfide, hydrogen sulfide, lithium halides (e.g., LiI, LiBr, LiCl), and sulfides of the elements represented by M above (e.g., SiS, SnS, GeS).

[0041] In the Li-PS glass and Li-PS glass ceramics, the ratio of Li2S to P2S5 is preferably 60:40 to 90:10, more preferably 68:32 to 78:22, in terms of the molar ratio of Li2S:P2S5. By setting the ratio of Li2S to P2S5 within this range, the lithium ion conductivity can be increased. Specifically, the lithium ion conductivity is preferably 1×10 -4 S / cm or more, preferably 1×10 -3 S / cm or more. There is no upper limit, but it is 1×10 -1 It is practical to have a value of S / cm or less.

[0042] Specific examples of sulfide-based inorganic solid electrolytes, including combinations of raw materials, are shown below: 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-Al2S3 , Li2S-GeS2, Li2S-GeS2-ZnS, Li2S-Ga2S3, Li2S-GeS2-Ga2S3, Li2S-GeS2-P2S5, Li2S-GeS2-Sb2S5, Li2S-GeS2-Al2S3, Li2S-SiS2, L i2S-Al2S3, Li2S-SiS2-Al2S3, Li2S-SiS2-P2S5, Li2S-SiS2-P2S5-LiI, Li2S-SiS2-LiI, Li2S-SiS2-Li4SiO4, Li2S-SiS2-Li3PO4, Li 10 GeP2S 12 However, the mixing ratio of each raw material is not important. As a method for synthesizing a sulfide-based inorganic solid electrolyte material using such a raw material composition, for example, an amorphization method can be mentioned. Examples of the amorphization method include a mechanical milling method, a solution method, and a melt quenching method. This is because processing at room temperature becomes possible, and the manufacturing process can be simplified.

[0043] (ii) Oxide-based inorganic solid electrolyte The oxide-based inorganic solid electrolyte preferably contains oxygen atoms, has the ionic conductivity of a metal belonging to Group 1 or 2 of the periodic table, and has electronic insulation properties. Oxide-based inorganic solid electrolytes have an ionic conductivity of 1×10 -6 S / cm or more is preferable, and 5×10 -6 S / cm or more is more preferable, and 1×10 -5 It is particularly preferable that the viscosity is 1×10 S / cm or more. -1It is practical that it is below S / cm.

[0044] Specific compound examples include, for example, Li xa La ya TiO3 [xa satisfies 0.3 ≤ xa ≤ 0.7, and ya satisfies 0.3 ≤ ya ≤ 0.7.](LLT); Li xb La yb Zr zb M bb mb O nb (M bb is one or more elements selected from Al, Mg, Ca, Sr, V, Nb, Ta, Ti, Ge, In and Sn. xb satisfies 5 ≤ xb ≤ 10, yb satisfies 1 ≤ yb ≤ 4, zb satisfies 1 ≤ zb ≤ 4, mb satisfies 0 ≤ mb ≤ 2, and nb satisfies 5 ≤ nb ≤ 20.); Li xc B yc M cc zc O nc (M cc is one or more elements 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, and nd satisfies 3 ≤ nd ≤ 13.); Li (3-2xe) M ee xe D ee O(xe represents a number from 0 or more to 0.1 or less, and M ee represents a divalent metal atom. D ee )]]represents 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, and zf satisfies 1 ≤ zf ≤ 10.); Lixg S yg O zg (xg satisfies 1 ≤ xg ≤ 3, yg satisfies 0 < yg ≤ 2, and zg satisfies 1 ≤ zg ≤ 10); Li3BO3; Li3BO3-Li2SO4; Li2O-B2O3-P2O5; Li2O-SiO2; Li6BaLa2Ta2O 12 ; Li3PO (4-3 / 2w) N w (w is w < 1); Li having a LISICON (Lithium super ionic conductor) type crystal structure 3.5 Zn 0.25 GeO4; La having a perovskite type crystal structure 0.55 Li 0.35 TiO3; LiTi2P3O having a NASICON (Natrium super ionic conductor) type 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 and yh satisfies 0 ≤ yh ≤ 1); Li7La3Zr2O having a garnet type crystal structure 12 (LLZ), etc. can be mentioned. Also, phosphorus compounds containing Li, P, and O are desirable. For example, lithium phosphate (Li3PO4); LiPON in which part of the oxygen element of lithium phosphate is substituted with a nitrogen element; LiPOD 1 (D 1 is preferably one or more elements selected from Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zr, Nb, Mo, Ru, Ag, Ta, W, Pt, and Au.) etc. can be mentioned. Furthermore, LiA 1 ON (A 1 is one or more elements selected from Si, B, Ge, Al, C, and Ga.) etc. can also be preferably used.

[0045] (iii) Halide-based inorganic solid electrolyte The halide-based inorganic solid electrolyte is preferably a compound that contains a halogen atom, has ionic conductivity of a metal belonging to Group 1 or 2 of the periodic table, and has electronic insulation properties. The halide-based inorganic solid electrolyte is not particularly limited, but examples thereof include LiCl, LiBr, LiI, and compounds such as Li3YBr6 and Li3YCl6 described in ADVANCED MATERIALS, 2018, 30, 1803075. Of these, Li3YBr6 and Li3YCl6 are preferred.

[0046] (iv) Hydride-based inorganic solid electrolytes The hydride-based inorganic solid electrolyte is preferably a compound that contains hydrogen atoms, has the ionic conductivity of a metal belonging to Group 1 or 2 of the periodic table, and has electronic insulation properties. The hydride-based inorganic solid electrolyte is not particularly limited, but examples thereof include LiBH4, Li4(BH4)3I, 3LiBH4-LiCl, and the like.

[0047] The inorganic solid electrolyte may be contained in one kind or in two or more kinds. The content of the inorganic solid electrolyte in the electrode composition is not particularly limited, but in terms of dispersibility, ionic conductivity, etc., the total content including the active material is preferably 50% by mass or more, more preferably 70% by mass or more, and particularly preferably 90% by mass or more, based on 100% by mass of solid content. From the same viewpoint, the upper limit is preferably 99.9% by mass or less, more preferably 99.5% by mass or less, and particularly preferably 99% by mass or less. In the present invention, the solid content (solid components) refers to components that do not volatilize or vaporize when the electrode composition is dried at 150°C under a nitrogen atmosphere at an atmospheric pressure of 1 mmHg for 6 hours. Typically, this refers to components other than the dispersion medium described below.

[0048] In the electrode composition, the content ratio of the inorganic solid electrolyte to the active material described later [content of inorganic solid electrolyte: content of active material] is not particularly limited, and the median diameter D 50It is set appropriately taking into consideration the above, etc. For example, the content ratio [content of inorganic solid electrolyte: content of active material] can be 1:1 to 1:10, and preferably 1:1 to 1:6.

[0049] <Active material> The electrode composition of the present invention may also contain an active material capable of inserting and releasing ions of a metal belonging to Group 1 or 2 of the periodic table. The active material contained in the electrode composition of the present invention is in a particulate form at least in the electrode composition. The shape of the particles is not particularly limited and may be flat, amorphous, etc., but spherical or granular is preferred.

[0050] The average particle size (median diameter D A-50 ) is the median diameter D 50 As long as the above condition is satisfied, there are no particular limitations and the value can be set appropriately. A-50 is preferably 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, from the viewpoints of, for example, dispersibility, conductivity, etc. The lower limit of the average particle size is practically 0.01 μm or more, and for example, is preferably 0.05 μm or more, more preferably 0.2 μm or more, and even more preferably 0.3 μm or more. The average particle size of the active material can be measured in the same manner as the particle size of the inorganic solid electrolyte. The method for adjusting the average particle size can be any of the known methods described for the inorganic solid electrolyte without any particular limitation.

[0051] The active material includes a positive electrode active material and a negative electrode active material. (Cathode active material) The positive electrode active material is an active material capable of inserting and releasing ions of a metal belonging to Group 1 or 2 of the periodic table, and is preferably one that can insert and release lithium ions reversibly. The material is not particularly limited as long as it has the above-mentioned properties, and may be a transition metal oxide, an organic substance, sulfur, or other element that can be composited with Li when the battery is disassembled. Among these, it is preferable to use a transition metal oxide as the positive electrode active material, and a transition metal element M a A transition metal oxide containing at least one element selected from Co, Ni, Fe, Mn, Cu, and V is more preferred. b (Elements of Group 1 (Ia) of the periodic table other than lithium, elements of Group 2 (IIa), Al, Ga, In, Ge, Sn, Pb, Sb, Bi, Si, P, B, etc.) may be mixed. The amount of the mixed element is determined by the following formula: a The amount of Li / M is preferably 0 to 30 mol % relative to the amount of Li (100 mol %). a More preferably, the compounds are synthesized by mixing them so that the molar ratio is 0.3 to 2.2. Specific examples of transition metal oxides include (MA) transition metal oxides having a layered rock salt structure, (MB) transition metal oxides having a spinel structure, (MC) lithium-containing transition metal phosphate compounds, (MD) lithium-containing transition metal halide phosphate compounds, and (ME) lithium-containing transition metal silicate compounds.

[0052] (MA) Specific examples of transition metal oxides with a layered rock salt structure include LiCoO2 (lithium cobalt oxide [LCO]), LiNi2O2 (lithium nickel oxide), and LiNi 0.85 Co 0.10 Al 0.05 O2 (nickel cobalt lithium aluminate [NCA]), LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (lithium nickel manganese cobalt oxide [NMC]) and LiNi 0.5 Mn 0.5 O2 (lithium manganese nickel oxide). (MB) Specific examples of transition metal oxides having a spinel structure include LiMn2O4 (LMO), LiCoMnO4, Li2FeMn3O8, Li2CuMn3O8, Li2CrMn3O8, and Li2NiMn3O8. (MC) Examples of lithium-containing transition metal phosphate compounds 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). (MD) Examples of lithium-containing transition metal halide phosphate compounds include iron fluorophosphates such as Li2FePO4F, manganese fluorophosphates such as Li2MnPO4F, and cobalt fluorophosphates such as Li2CoPO4F. (ME) Examples of lithium-containing transition metal silicate compounds include Li2FeSiO4, Li2MnSiO4, and Li2CoSiO4. In the present invention, transition metal oxides having a layered rock salt structure (MA) are preferred, and LCO or NMC are more preferred.

[0053] The positive electrode active material obtained by the baking method may be used after being washed with water, an acidic aqueous solution, an alkaline aqueous solution, or an organic solvent.

[0054] The electrode composition may contain one or more positive electrode active materials.

[0055] The content of the positive electrode active material in the electrode composition is not particularly limited, and is preferably 10 to 97 mass%, more preferably 30 to 95 mass%, even more preferably 40 to 93 mass%, and particularly preferably 50 to 90 mass%, based on 100 mass% of the solid content.

[0056] (Negative electrode active material) The negative electrode active material is an active material capable of inserting and releasing ions of a metal belonging to Group 1 or 2 of the periodic table, and is preferably one that can insert and release lithium ions reversibly. The material is not particularly limited as long as it has the above-mentioned properties, and examples thereof include carbonaceous materials, metal oxides, metal composite oxides, lithium alone, lithium alloys, and negative electrode active materials that can form an alloy (can be alloyed) with lithium. Among these, carbonaceous materials, metal composite oxides, and lithium alone are preferably used from the viewpoint of reliability. Active materials that can be alloyed with lithium are preferred in that they enable the production of all-solid-state secondary batteries with a large capacity.

[0057] The carbonaceous material used as the negative electrode active material is a material essentially composed of carbon. Examples include carbon black such as petroleum pitch and acetylene black (AB), graphite (natural graphite, artificial graphite such as vapor-grown graphite, etc.), and carbonaceous materials obtained by calcining various synthetic resins such as PAN (polyacrylonitrile)-based resins and furfuryl alcohol resins. Further examples include various carbon fibers such as PAN-based carbon fiber, cellulose-based carbon fiber, pitch-based carbon fiber, vapor-grown carbon fiber, dehydrated PVA (polyvinyl alcohol)-based carbon fiber, lignin carbon fiber, glassy carbon fiber, and activated carbon fiber, as well as mesophase microspheres, graphite whiskers, and tabular graphite. These carbonaceous materials can be divided into non-graphitizable carbonaceous materials (also called hard carbon) and graphite-based carbonaceous materials depending on the degree of graphitization. Furthermore, the carbonaceous material preferably has the interplanar spacing, density, and crystallite size described in JP-A-62-22066, JP-A-2-6856, and JP-A-3-45473. The carbonaceous material does not need to be a single material, and a mixture of natural graphite and artificial graphite described in JP-A-5-90844, graphite with a coating layer described in JP-A-6-4516, and the like can also be used. As the carbonaceous material, hard carbon or graphite is preferably used, and graphite is more preferably used.

[0058] The oxide of a metal or metalloid element used as the negative electrode active material is not particularly limited as long as it is an oxide capable of absorbing and releasing lithium, and examples thereof include oxides of metal elements (metal oxides), composite oxides of metal elements, or composite oxides of metal elements and metalloid elements (collectively referred to as metal composite oxides), and oxides of metalloid elements (metalloid oxides). Amorphous oxides are preferred as these oxides, and chalcogenides, which are reaction products of metal elements and elements of Group 16 of the periodic table, are also preferred. In the present invention, the term "metalloid element" refers to an element exhibiting properties intermediate between metal elements and non-metalloid elements, and typically includes six elements: boron, silicon, germanium, arsenic, antimony, and tellurium, and three elements: selenium, polonium, and astatine. Furthermore, "amorphous" refers to an element that exhibits a broad scattering band with a peak in the 2θ range of 20° to 40° in an X-ray diffraction method using CuKα radiation, and may also have crystalline diffraction lines. The strongest intensity of the crystalline diffraction lines seen at 2θ values ​​of 40° to 70° is preferably 100 times or less, more preferably 5 times or less, the diffraction line intensity at the apex of the broad scattering band seen at 2θ values ​​of 20° to 40°, and it is particularly preferable that there are no crystalline diffraction lines.

[0059] Among the compounds consisting of the amorphous oxides and chalcogenides, amorphous oxides or chalcogenides of metalloid elements are more preferred, and (composite) oxides or chalcogenides consisting of one or a combination of two or more elements selected from the elements of 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 Ga2O3, GeO, PbO, PbO2, Pb2O3, Pb2O4, Pb3O4, Sb2O3, Sb2O4, Sb2O8Bi2O3, Sb2O8Si2O3, Sb2O5, Bi2O3, Bi2O4, GeS, PbS, PbS2, Sb2S3, and Sb2S5. Suitable examples of negative electrode active materials that can be used in combination with amorphous oxides mainly containing Sn, Si, or Ge include carbonaceous materials that can occlude and / or release lithium ions or lithium metal, lithium alone, lithium alloys, and negative electrode active materials that can be alloyed with lithium.

[0060] From the viewpoint of high current density charge / discharge characteristics, it is preferable that the oxides of metal or semi-metal elements, particularly the metal (composite) oxides and the chalcogenides contain at least one of titanium and lithium as a constituent component. Examples of lithium-containing metal composite oxides (lithium composite metal oxides) include composite oxides of lithium oxide and the metal (composite) oxides or the chalcogenides, more specifically Li2SnO2. The negative electrode active material, for example, a metal oxide, preferably contains titanium (titanium oxide). Specifically, Li4Ti5O 12 Lithium titanate (LTO) is preferred because it has excellent rapid charge / discharge characteristics due to its small volume change when absorbing and releasing lithium ions, and it can suppress electrode deterioration and improve the lifespan of lithium ion secondary batteries.

[0061] The lithium alloy used as the negative electrode active material is not particularly limited as long as it is an alloy that is commonly used as a negative electrode active material for secondary batteries, and examples thereof include lithium-aluminum alloys, specifically lithium-aluminum alloys having lithium as the base metal and 10 mass % of aluminum added thereto.

[0062] The negative electrode active material capable of forming an alloy with lithium is not particularly limited as long as it is one that is commonly used as a negative electrode active material for secondary batteries. Examples of such active materials include (negative electrode) active materials (alloys, etc.) containing silicon or tin, and metals such as Al and In. A negative electrode active material containing silicon (silicon-containing active material) that enables higher battery capacity is preferred, and a silicon-containing active material in which the silicon content of all constituent elements is 50 mol % or more is more preferred. Generally, negative electrodes containing these negative electrode active materials (for example, Si negative electrodes containing silicon element-containing active materials, Sn negative electrodes containing active materials having tin elements, etc.) can occlude more Li ions than carbon negative electrodes (such as graphite and acetylene black). That is, the amount of Li ions occluded per unit mass increases. Therefore, the battery capacity (energy density) can be increased. As a result, there is an advantage that the battery driving time can be lengthened. Examples of the silicon element-containing active material include silicon materials such as Si and SiOx (0 < x ≦ 1), and further silicon-containing alloys containing titanium, vanadium, chromium, manganese, nickel, copper, lanthanum, etc. (for example, LaSi2, VSi2, La-Si, Gd-Si, Ni-Si), or organized active materials (for example, LaSi2 / Si). In addition, active materials containing silicon elements and tin elements such as SnSiO3 and SnSiS3 can also be mentioned. Note that SiOx can be used as a negative electrode active material (semimetal oxide) itself, and can also be used as a negative electrode active material (its precursor material) that can be alloyed with lithium because Si is generated by the operation of all-solid-state secondary batteries. Examples of the negative electrode active material having a tin element include Sn, SnO, SnO2, SnS, SnS2, and further active materials containing the above silicon element and tin element. In addition, composite oxides with lithium oxide, for example, Li2SnO2, can also be mentioned.

[0063] In the present invention, the above-described negative electrode active materials can be used without particular limitation. However, from the viewpoint of battery capacity, a negative electrode active material that can be alloyed with lithium is a preferred embodiment as the negative electrode active material. Among them, the above silicon material or silicon-containing alloy (alloy containing silicon element) is more preferred, and it is still more preferred to include silicon (Si) or a silicon-containing alloy.

[0064] The negative electrode active material contained in the electrode composition may be one kind or two or more kinds.

[0065] The content of the negative electrode active material in the electrode composition is not particularly limited, and is preferably 10 to 90 mass %, more preferably 20 to 85 mass %, even more preferably 30 to 80 mass %, and still more preferably 40 to 75 mass %, based on 100 mass % of the solid content.

[0066] The chemical formula of the compound obtained by the above calcination method can be measured by inductively coupled plasma (ICP) emission spectroscopy, or simply calculated from the difference in mass of the powder before and after calcination.

[0067] (Coating of active material) The surfaces of the positive electrode active material and the negative electrode active material may be coated with another metal oxide. Examples of the surface coating agent include metal oxides containing Ti, Nb, Ta, W, Zr, Al, Si, or Li. Specific examples include titanate spinel, tantalum-based oxides, niobium-based oxides, and lithium niobate-based compounds, such as Li4Ti5O 12 , Li2Ti2O5, LiTaO3, LiNbO3, LiAlO2, Li2ZrO3, Li2WO4, Li2TiO3, Li2B4O7, Li3PO4, Li2MoO4, Li3BO3, LiBO2, Li2CO3, Li2SiO3, SiO2, TiO2, ZrO2, Al2O3, B2O3, etc. The surface of the electrode containing the positive electrode active material or the negative electrode active material may be surface-treated with sulfur or phosphorus. Furthermore, the particle surfaces of the positive electrode active material or negative electrode active material may be subjected to a surface treatment with active rays or active gas (plasma, etc.) before or after the above surface coating.

[0068] <Polymer binder> The polymer binder contained in the electrode composition of the present invention is a binder containing a linear polymer. When the polymer binder contains a linear polymer, the above-mentioned radius of gyration α and median diameter D 50 This reinforces the effect of the relationship that satisfies the above, thereby suppressing the occurrence of dripping and uneven application of the electrode composition and improving ionic conductivity. In the present invention, a linear polymer refers to a polymer having a main chain formed by linear polymerization or condensation of polycondensable compounds, and having no branched polymer chains (including graft chains) or crosslinked structures. Examples of such a polymer include a chain polymer of a polymerizable compound having one carbon-carbon double bond, and a step-growth polymer of bifunctional condensable compounds. In the present invention, the main chain of a polymer refers to a linear molecular chain in which all other molecular chains constituting the polymer can be considered as branched chains or pendant groups relative to the main chain. Typically, the longest chain among the molecular chains constituting the polymer becomes the main chain, although this depends on the mass average molecular weight of the branched chains considered as branched chains or pendant groups. However, terminal groups at the polymer ends are not included in the main chain. Furthermore, the side chain of a polymer refers to branched chains other than the main chain, and includes short and long chains.

[0069] - Physical properties or characteristics of linear polymers or polymer binders - The linear polymer preferably satisfies the SP value range below, and the polymer binder preferably exhibits an adsorption rate and solubility in the dispersion medium within the range below. Furthermore, in addition to these physical properties or characteristics, the polymer binder or linear polymer preferably also has the following physical properties or characteristics as appropriate.

[0070] The SP value, which is a preferable property of the linear polymer, is not particularly limited, and is, for example, 12.0 to 21.5 MPa. 1 / 2 However, in terms of dispersibility of the electrode composition, a pressure of 12.0 to 21.5 MPa is preferred. 1 / 2 Preferably, the pressure is 16 to 20 MPa. 1 / 2 More preferably, it is 17 to 20 MPa. 1 / 2 More preferably, the pressure is 17 to 19.5 MPa. 1 / 2 It is particularly preferable that the pressure is 18 to 19.5 MPa. 1 / 2 It is most preferable that: The method for calculating the SP value will be explained. First, the SP value (MPa) of each component (structural unit) that makes up the linear polymer 1 / 2) is determined by the Hoy method (HL Hoy JOURNAL OF PAINT TECHNOLOGY Vol. 42, No. 541, 1970, 76-118, and POLYMER HANDBOOK 4 th , Chapter 59, VII, p. 686, Table 5, Table 6 and the following formula in Table 6).

[0071]

number

[0072] The components determined as above and the SP value (MPa 1 / 2 ) to obtain the SP of the linear polymer. p Value (MPa 1 / 2 The SP values ​​of the constituent components obtained in accordance with the above document are calculated using the SP values ​​(MPa 1 / 2 ) (for example, 1 cal 1 / 2 cm -3 / 2 ≒2.05J 1 / 2 cm -3 / 2 ≒2.05 MPa 1 / 2 ) and use it. SP p 2 =(SP1 2 ×W1)+(SP2 2 ×W2)+··· 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 the present invention, the mass fraction of a constituent component refers to the mass fraction of the constituent component (the raw material compound from which this constituent component is derived) in the linear polymer. The SP value of a polymer can be adjusted by the type or composition (type and content of constituent components) of the linear polymer.

[0073] It is preferable that the SP value of the linear polymer satisfy the difference (absolute value) in SP value with respect to the SP value of the dispersion medium within the range described below, in order to achieve even higher dispersibility.

[0074] The adsorption rate, which is a desirable property of the polymer binder, is the adsorption rate A of the active material contained in the electrode composition in the dispersion medium contained in the electrode composition. AM Although there is no particular limitation, it is preferable that the adsorption rate A of the active material is 40% or less. AM When the content is 40% or less, the active material is not excessively adsorbed, which contributes to improving the dispersibility and further improving the conductivity. In the present invention, the adsorption rate A of the polymer binder AM is a value measured using the active material and dispersion medium contained in the electrode composition, and is an index showing the degree of adsorption of the polymer binder to the active material in the dispersion medium. Here, adsorption of the polymer binder to the active material includes not only physical adsorption but also chemical adsorption (adsorption by chemical bond formation, adsorption by electron exchange, etc.). When the electrode composition contains multiple types of active materials, the adsorption rate is measured for an active material having the same composition (type and content) as the active material composition in the electrode composition. Similarly, when the electrode composition contains multiple types of dispersion medium, the adsorption rate is measured using a dispersion medium having the same composition (type and content) as the dispersion medium in the electrode composition. Furthermore, when multiple types of polymer binders are used, the adsorption rate is measured for the multiple types of polymer binders, as in the electrode composition. In the present invention, the adsorption rate of the polymer binder is a value calculated by the method described in the examples. In the present invention, the adsorption rate A AM can be appropriately set depending on the type of polymer contained in the polymer binder (structure and composition of the polymer chain), the type or content of functional groups possessed by the polymer, the form of the polymer binder (amount dissolved in the dispersion medium), etc. Adsorption rate A AM The adsorption rate A can be set to 60% or less, preferably 45% or less, and more preferably 30% or less, in order to further increase the dispersibility. AM The lower limit of the adsorption rate is not particularly limited and can be 0%. From the viewpoint of dispersibility, the lower limit of the adsorption rate is preferably as small as possible, for example, preferably 0.1% or more, more preferably 1% or more.

[0075] A preferred property of the polymer binder (linear polymer) is that it dissolves in the dispersion medium contained in the electrode composition (solubility). The polymer binder in the electrode composition is usually present in a dissolved state in the dispersion medium, although this depends on the content. This allows the polymer binder to stably perform its function of dispersing solid particles in the dispersion medium. In the present invention, the polymer binder being dissolved in the dispersion medium in the electrode composition is not limited to an embodiment in which all of the polymer binder is dissolved in the dispersion medium, and a part of the polymer binder may be insoluble in the electrode composition as long as the solubility in the dispersion medium is, for example, 80% or more. The solubility is measured as follows. Specifically, a specified amount of the polymer binder to be measured is weighed into a glass bottle, and 100 g of the same type of dispersion medium as the dispersion medium contained in the electrode composition is added thereto. The mixture is stirred for 24 hours at 80 rpm on a mix rotor at a temperature of 25°C. The transmittance of the mixture thus obtained after 24 hours of stirring is measured under the following conditions. This test (transmittance measurement) is performed by changing the amount of binder dissolved (the above-specified amount), 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 above-specified dispersion medium. <Transmittance measurement conditions> Dynamic light scattering (DLS) measurements Equipment: DLS measurement equipment DLS-8000 manufactured by Otsuka Electronics Laser wavelength, output: 488nm / 100mW Sample cell: NMR tube

[0076] The linear polymer may have a radius of gyration α within the above range, and its mass average molecular weight is not particularly limited and is appropriately set in consideration of the radius of gyration α. ​​The mass average molecular weight of the linear polymer can be, for example, 10,000 or more, preferably 15,000 or more, more preferably 30,000 or more, and even more preferably 50,000 or more. The upper limit is essentially 5,000,000 or less, but is 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. The mass average molecular weight of the fluorine-based polymer described later can be set within the above range, but taking into consideration the radius of gyration α, etc., it is more preferably 150,000 or more, particularly preferably 200,000 or more, and most preferably 300,000 or more. The upper limit is more preferably 1,500,000 or less, particularly preferably 1,200,000 or less.

[0077] - Molecular weight measurement - In the present invention, unless otherwise specified, the molecular weight of a polymer, polymer chain, or macromonomer refers to the mass average molecular weight or number average molecular weight measured by gel permeation chromatography (GPC) in terms of standard polystyrene. The measurement method can be basically the following Condition 1 or Condition 2 (preferred). However, depending on the type of polymer or macromonomer, an appropriate eluent may be selected and used. (Condition 1) Column: Two TOSOH TSKgel Super AWM-H (product name, manufactured by Tosoh Corporation) connected together Carrier: 10mM LiBr / N-methylpyrrolidone Measurement temperature: 40℃ Carrier flow rate: 1.0 ml / min Sample concentration: 0.1% by mass Detector: RI (refractive index) detector (Condition 2) Column: A column connected with TOSOH TSKgel Super HZM-H, TOSOH TSKgel Super HZ4000, or TOSOH TSKgel Super HZ2000 (all trade names, manufactured by Tosoh Corporation) is used. Carrier: Tetrahydrofuran Measurement temperature: 40℃ Carrier flow rate: 1.0 ml / min Sample concentration: 0.1% by mass Detector: RI (refractive index) detector

[0078] The water concentration of the polymer binder (linear polymer) is preferably 100 ppm (by mass) or less. The polymer binder may be prepared by crystallizing the polymer and drying it, or the polymer binder dispersion may be used as is.

[0079] The linear polymer is preferably amorphous. In the present invention, a polymer being "amorphous" typically means that no endothermic peak due to crystalline melting is observed when measured at the glass transition temperature.

[0080] - Linear polymer - The linear polymer is not particularly limited in type, composition, etc., as long as it satisfies the above-mentioned preferred characteristics or physical properties, and various polymers can be used as binder polymers for all-solid-state secondary batteries. The linear polymer preferably contains a constituent component having a functional group with a pKa of 8 or less. When the linear polymer contains this constituent component, the radius of gyration α can be set within an appropriate range, and the polymer binder can further improve the coatability and ionic conductivity of the electrode composition. This constituent has a functional group with a pKa of 8 or less, either directly or via a linking group, in a partial structure to be incorporated into the main chain of the linear polymer. The partial structure to be incorporated into the main chain of the linear polymer is appropriately selected depending on the type of linear polymer, and examples thereof include a carbon chain (carbon-carbon bond). pKa refers to 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 of sodium hydroxide solution dropwise to an aqueous solution of the polymer binder and measuring the amount of sodium hydroxide solution added up to the half-equivalent point. Functional groups with a pKa of 8 or less are not particularly limited, and examples include acidic functional groups such as carboxyl groups, phosphoryl groups (phosphate groups), phosphonic acid groups, and sulfo groups (sulfonic acid groups), as well as phenolic hydroxyl groups. The linking group is not particularly limited, and examples thereof include an alkylene group (preferably having 1 to 12 carbon atoms, more preferably having 1 to 6 carbon atoms, and even more preferably having 1 to 3 carbon atoms), an alkenylene group (preferably having 2 to 6 carbon atoms, and more preferably having 2 to 3 carbon atoms), an arylene group (preferably having 6 to 24 carbon atoms, and more preferably having 6 to 10 carbon atoms), an oxygen atom, a sulfur atom, an imino group (—NR N -:R N represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 10 carbon atoms. ), a carbonyl group, a phosphate linking group (-OP(OH)(O)-O-), a phosphonate linking group (-P(OH)(O)-O-), or a group relating to a combination thereof. The linking group is preferably a group formed by combining an alkylene group, an arylene group, a carbonyl group, an oxygen atom, a sulfur atom, and an imino group, more preferably a group formed by combining an alkylene group, an arylene group, a carbonyl group, an oxygen atom, an imino group, or a polyalkyleneoxy chain (a combination of an alkylene group and an oxygen atom), and more preferably a -CO-O- group or a -CO-N(R N )-group(R N represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 10 carbon atoms. A group containing —CO—O— group or —CO—N(R N Examples of groups containing a -)- group include groups further containing an alkylene group, an arylene group, a -CO-O- group, a polyalkyleneoxy chain, etc. The number of atoms constituting the linking group and the number of linked atoms are as follows. However, the polyalkyleneoxy chain constituting the linking group is not limited to the above. In the present 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 linking atoms in the linking group is preferably 10 or less, more preferably 8 or less. The lower limit is 1 or more. The number of linking atoms refers to the minimum number of atoms connecting predetermined structural moieties. For example, in the case of -CH2-C(=O)-O-, the number of atoms constituting the linking group is 6, but the number of linking atoms is 3.

[0081] The partial structure and linking group incorporated into the main chain may each have a substituent. Such a substituent is not particularly limited and examples thereof include groups selected from the substituent Z described below.

[0082] The constituent having a functional group with a pKa of 8 or less can be formed by appropriately combining the partial structure incorporated into the main chain, the functional group with a pKa of 8 or less, and further the linking group. For example, a constituent derived from a (meth)acrylic acid compound described below, a constituent derived from a compound obtained by introducing a functional group with a pKa of 8 or less into a (meth)acrylic compound (M1), or a constituent derived from a compound obtained by introducing a functional group with a pKa of 8 or less into a vinyl compound (M2) described below is preferred. Examples include (meth)acrylic acid compounds, acrylic acid ester compounds having a functional group with a pKa of 8 or less introduced, vinyl compounds (M2) having a functional group with a pKa of 8 or less introduced (particularly, styrene compounds having a functional group with a pKa of 8 or less introduced, and ring-opened compounds (including monoesters) of unsaturated carboxylic acid anhydrides (e.g., maleic anhydride compounds), etc.). When the ring-opened compound of the unsaturated carboxylic acid anhydride is a monoester, the group forming the ester is not particularly limited, and examples include groups selected from the substituent Z described below, with alkyl groups being preferred. Specific examples of components having a functional group with a pKa of 8 or less include components in the linear polymers described in the Examples and below, but the present invention is not limited to these.

[0083] The linear polymer may have one or more constituent components having a functional group with a pKa of 8 or less. The content of the constituent components having a functional group with a pKa of 8 or less in the linear polymer is determined by appropriately considering the radius of gyration α of the linear polymer, as well as the SP value, and the like, and details will be described later.

[0084] Preferred examples of the linear polymer include polymers having at least one bond selected from a urethane bond, a urea bond, an amide bond, an imide bond, and an ester bond, or a polymer chain of a carbon-carbon double bond in the main chain.

[0085] The bond is not particularly limited as long as it is contained in the main chain of the polymer, and may be contained in a constituent component (repeating unit) and / or as a bond connecting different constituent components. Furthermore, the number of bonds contained in the main chain is not limited to one, but may be two or more, preferably one to six, and more preferably one to four. In this case, the bonding pattern of the main chain is not particularly limited, and may include two or more types of bonds randomly, or may be a segmented main chain consisting of segments having specific bonds and segments having other bonds. The main chain having the above bond is not particularly limited, but is preferably a main chain having at least one segment of the above bonds, and more preferably a main chain made of polyamide, polyurea or polyurethane. Examples of polymers having a urethane bond, urea bond, amide bond, imide bond, or ester bond in the main chain include sequential polymerization (polycondensation, polyaddition, or addition-condensation) polymers such as polyurethane, polyurea, polyamide, polyimide, and polyester, or copolymers thereof. The copolymer may be a block copolymer having each of the above polymers as a segment, or a random copolymer in which the constituent components of two or more of the above polymers are randomly bonded.

[0086] Examples of polymers having a polymer chain of carbon-carbon double bonds in the main chain include chain-polymerized polymers such as fluorine-based polymers (fluorine-containing polymers), hydrocarbon-based polymers, vinyl-based polymers, (meth)acrylic polymers, etc. The polymerization mode of these chain-polymerized polymers is not particularly limited, and may be any of block copolymers, alternating copolymers, and random copolymers, with random copolymers being preferred. The linear polymer can be appropriately selected from the above-mentioned polymers, but is preferably a (meth)acrylic polymer, a fluorine-based polymer or a vinyl-based polymer, more preferably a (meth)acrylic polymer or a fluorine-based polymer.

[0087] Examples of (meth)acrylic polymers suitable as linear polymers include polymers consisting of a (meth)acrylic compound (M1), preferably a (co)polymer with a compound that further derives a component having a functional group with a pKa of 8 or less, the polymer containing 50% by mass or more of a component derived from a (meth)acrylic compound. Here, when the component having a functional group with a pKa of 8 or less is a (meth)acrylic acid compound or a component derived from a (meth)acrylic compound, the content of the component having a functional group with a pKa of 8 or less is included in the content of the component derived from the (meth)acrylic compound. Copolymers with vinyl monomers other than the (meth)acrylic compound (M1) are also preferred as (meth)acrylic polymers. A fluorine-containing polymer suitable as the linear polymer includes a (co)polymer of a polymerizable compound containing a fluorine atom (a fluorine-containing polymerizable compound). Further preferred fluorine-containing polymers include copolymers with a (meth)acrylic compound (M1), a vinyl monomer other than the (meth)acrylic compound (M1), or a compound that leads to a constituent having a functional group with a pKa of 8 or less. Examples of vinyl polymers suitable as linear polymers include polymers composed of copolymers containing 50% by mass or more of vinyl monomer-derived components, which are (co)polymers of vinyl monomers other than the (meth)acrylic compound (M1), preferably compounds that further derive a component having a functional group with a pKa of 8 or less. When the component having a functional group with a pKa of 8 or less is derived from a vinyl monomer, the content of the component having a functional group with a pKa of 8 or less is included in the content of the vinyl monomer-derived component. Furthermore, copolymers with a (meth)acrylic compound (M1) are also preferred as vinyl polymers.

[0088] Examples of the (meth)acrylic compound (M1) include (meth)acrylic acid ester compounds, (meth)acrylamide compounds, (meth)acrylonitrile compounds, etc., other than compounds that lead to components having a functional group with a pKa of 8 or less (compounds to which a functional group with a pKa of 8 or less has not been introduced). Among these, (meth)acrylic acid ester compounds and (meth)acrylamide compounds are preferred. Examples of (meth)acrylic acid ester compounds include (meth)acrylic acid alkyl ester compounds, (meth)acrylic acid aryl ester compounds, (meth)acrylic acid ester compounds having heterocyclic groups, and even polymerized chain (meth)acrylic acid ester compounds, with (meth)acrylic acid alkyl ester compounds being preferred. The number of carbon atoms in the alkyl group constituting the (meth)acrylic acid alkyl ester compound is not particularly limited, but can be, for example, 1 to 24. From the viewpoints of dispersibility and adhesion, it is preferably 3 to 20, more preferably 4 to 16, and even more preferably 6 to 14. In the present invention, the (meth)acrylic acid alkyl ester compound can be a combination of a (meth)acrylic acid ester compound having a long-chain alkyl group with 4 to 16 carbon atoms and a (meth)acrylic acid ester 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, but 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 may be substituted with an alkyl group or an aryl group. The polymer chain of the (meth)acrylic acid ester compound is not particularly limited, but is preferably an alkylene oxide polymer chain, and more preferably a polymer chain made of an alkylene oxide having 2 to 4 carbon atoms. The degree of polymerization of the polymer chain is not particularly limited and is set appropriately. An alkyl group or an aryl group is usually bonded to the end of the polymer chain.

[0089] The fluorine-containing polymerizable compound is not particularly limited, and examples thereof include compounds commonly used in fluorine-based polymers. For example, it refers to a compound in which a fluorine atom is bonded to a carbon-carbon double bond directly or via a linking group. The linking group is not particularly limited, and examples thereof include the linking groups in the above-mentioned components having a functional group with a pKa of 8 or less. The fluorine-containing polymerizable compound is not particularly limited, and examples thereof include fluorinated vinyl compounds such as vinylidene fluoride (VDF), hexafluoropropylene (HFP), tetrafluoroethylene (TFE), trifluoroethylene, monofluoroethylene, and chlorotrifluoroethylene, and perfluoroalkyl ether compounds such as trifluoromethyl vinyl ether and pentafluoroethyl vinyl ether.

[0090] The vinyl monomer is not particularly limited, but among vinyl compounds copolymerizable with (meth)acrylic compounds (M1) and the like, vinyl compounds (M2) other than vinyl compounds that lead to components having a functional group with a pKa of 8 or less are preferred, such as aromatic vinyl compounds such as styrene compounds, vinyl naphthalene compounds, and vinyl carbazole compounds, as well as compounds without a functional group with a pKa of 8 or less, such as allyl compounds, vinyl ether compounds, vinyl ester compounds, dialkyl itaconate compounds, and unsaturated carboxylic acid anhydrides. Examples of vinyl compounds include the "vinyl monomers" described in JP 2015-88486 A.

[0091] The (meth)acrylic compound (M1), the fluorine-containing polymerizable compound, and the vinyl compound (M2) may each have a substituent. The substituent is not particularly limited as long as it is a group other than a functional group having a pKa of 8 or less, and examples thereof include groups selected from the substituent Z described below.

[0092] The (meth)acrylic compound (M1) and the vinyl compound (M2) are preferably compounds represented by the following formula (b-1): This compound is preferably different from the above-mentioned compounds that lead to constituents having functional groups with a pKa of 8 or less.

[0093] [ka]

[0094] In the formula, R 1 represents a hydrogen atom, a hydroxy group, a cyano group, a halogen atom, an alkyl group (preferably having 1 to 24 carbon atoms, more preferably having 1 to 12 carbon atoms, and particularly preferably having 1 to 6 carbon atoms), an alkenyl group (preferably having 2 to 24 carbon atoms, more preferably having 2 to 12 carbon atoms, and particularly preferably having 2 to 6 carbon atoms), an alkynyl group (preferably having 2 to 24 carbon atoms, more preferably having 2 to 12 carbon atoms, and particularly preferably having 2 to 6 carbon atoms), or an aryl group (preferably having 6 to 22 carbon atoms, and more preferably having 6 to 14 carbon atoms). Among these, a hydrogen atom or an alkyl group is preferred, and a hydrogen atom or a methyl group is more preferred.

[0095] R 2 represents a hydrogen atom or a substituent. 2 The substituent that can be taken as is not particularly limited, but examples thereof include an alkyl group (which may be branched but is preferably straight), an alkenyl group (preferably having 2 to 12 carbon atoms, more preferably having 2 to 6 carbon atoms, and particularly preferably having 2 or 3 carbon atoms), an aryl group (preferably having 6 to 22 carbon atoms, more preferably having 6 to 14 carbon atoms), an aralkyl group (preferably having 7 to 23 carbon atoms, more preferably having 7 to 15 carbon atoms), and a cyano group. The number of carbon atoms in the alkyl group is the same as the number of carbon atoms in the alkyl group constituting the above-mentioned (meth)acrylic acid alkyl ester compound, and the preferred range is also the same.

[0096] L 1 is a linking group, and is not particularly limited, but examples thereof include the linking groups in the constituent components having the above-mentioned functional groups with a pKa of 8 or less. L 1 is a -CO-O- group or a -CO-N(R N )-group(R N is as above.) (However, -O- or -N(R N )- is R 2 and (the mode of bonding with), the compound represented by the above formula (b-1) corresponds to the (meth)acrylic compound (M1), and the others correspond to the vinyl compound (M2).

[0097] n is 0 or 1, preferably 1, provided that -(L 1 ) n -R 2 When R represents one type of substituent (for example, an alkyl group), n is set to 0, and R 2 is the substituent (alkyl group).

[0098] The (meth)acrylic compound (M1) is preferably a compound represented by the following formula (b-2) or (b-3): These compounds are preferably different from the compounds mentioned above that lead to constituents having functional groups with a pKa of 8 or less.

[0099] [ka]

[0100] R 1 , n has the same meaning as in the above formula (b-1). R 3 is R 2 is synonymous with. L 2 is a linking group, and the above L 1 is synonymous with. L 3 is a linking group, and the above L 1 However, an alkylene group having 1 to 6 carbon atoms (preferably 2 to 4 carbon atoms) is preferred. m is preferably an integer of 1 to 200, more preferably an integer of 1 to 100, and even more preferably an integer of 1 to 50.

[0101] In the above formulas (b-1) to (b-3), the carbon atom forming the polymerizable group is R 1 The carbon atom to which R is not bonded is represented as an unsubstituted carbon atom (HC=), but it may have a substituent. The substituent is not particularly limited, but for example, R 1 Examples of the groups that can be taken as the substituent include the above groups. In addition, in formulas (b-1) to (b-3), groups that may have a substituent, such as an alkyl group, an aryl group, an alkylene group, or an arylene group, may have a substituent within a range that does not impair the effects of the present invention. The substituent is not particularly limited, and examples thereof include groups selected from the substituent Z described below, and specific examples thereof include a halogen atom.

[0102] Specific examples of the (meth)acrylic compound (M1) and the vinyl compound (M2) include compounds that lead to the constituent components of the linear polymers described in the Examples and below, but the present invention is not limited to these. The linear polymer may contain one or more of the above (meth)acrylic compound (M1), fluorine-containing polymerizable compound or vinyl-based monomer.

[0103] The linear polymer may have or not have a component derived from a macromonomer having a number-average molecular weight of 1,000 or more. In the present invention, a component not derived from a macromonomer is preferred. The macromonomer having a number-average molecular weight of 1,000 or more is not particularly limited as long as it does not include a compound represented by any of the above formulas (b-1) to (b-3), and examples thereof include macromonomer (X) described in JP 2015-088486 A.

[0104] The content of each component in the linear polymer is not particularly limited and is determined taking into consideration the radius of gyration α of the polymer, the SP value, and the like, as appropriate, and is set, for example, within the following ranges. The content of each constituent component in the (meth)acrylic polymer is set, for example, within the following ranges so that the total content of all constituent components is 100% by mass. The content of components derived from (meth)acrylic compounds (components derived from (meth)acrylic compounds and components derived from (meth)acrylic compounds (M1) among components having a functional group with a pKa of 8 or less) 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 be 100% by mass, but can also be 98% by mass or less. The content of the constituent component derived from the (meth)acrylic compound (M1) (excluding constituent components having a functional group with a pKa of 8 or less) is, for example, preferably 45 to 100 mass%, more preferably 50 to 100 mass%, even more preferably 70 to 100 mass%, and particularly preferably 90 to 98 mass%. The content of the component having a functional group with a pKa of 8 or less is, for example, preferably 0 to 55 mass%, more preferably 1 to 30 mass%, even more preferably 3 to 20 mass%, and particularly preferably 3 to 7 mass%. The content of components derived from vinyl compounds (excluding 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, and more preferably 0 to 30% by mass. The content of components derived from styrene compounds, among vinyl compounds, is set in consideration of the above range, but is preferably 0 to 40% by mass, and more preferably 10 to 30% by mass. The content of the constituent component derived from the macromonomer is preferably, for example, 0 to 30% by mass.

[0105] The content of each constituent component in the fluoropolymer is set, for example, within the following range so that the total content of all constituent components is 100% by mass. The content of components derived from fluorine-containing polymerizable compounds (components derived from fluorine-containing polymerizable compounds among components having a functional group with a pKa of 8 or less and components derived from fluorine-containing polymerizable compounds without a functional group with a pKa of 8 or less) is not particularly limited, and is, for example, more preferably 60% by mass or more, and even more preferably 80% by mass or more. The upper limit of the content can be 100% by mass, but is preferably 97% by mass or less, and more preferably 94% by mass or less. The content of components derived from fluorine-containing polymerizable compounds (excluding components having functional groups with a pKa of 8 or less) is, for example, 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 components derived from vinylidene fluoride compounds among fluorine-containing polymerizable compounds is set in consideration of the above range, but is preferably 50 to 90% by mass, and more preferably 60 to 85% by mass. The content of components derived from hexafluoropropylene compounds is set in consideration of the above range, but is preferably 10 to 50% by mass, and more preferably 15 to 40% by mass. The content of the constituent component having a functional group with a pKa of 8 or less is, for example, preferably 0 to 30 mass %, more preferably 0 to 20 mass %, and even more preferably 0.05 to 10 mass %. The content of each of the constituent component derived from the (meth)acrylic compound (M1), the constituent component derived from the vinyl compound, and the constituent component derived from the macromonomer is not particularly limited, and can be, for example, 0 to 15% by mass.

[0106] The content of each component in the vinyl polymer is set, for example, within the following range so that the total content of all components is 100% by mass. The content of vinyl monomer-derived components (components having a functional group with a pKa of 8 or less that are derived from vinyl monomers and components derived from vinyl monomers other than the (meth)acrylic 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 be 100% by mass, but can also be 90% by mass or less. The content of components derived from vinyl compounds (excluding components having functional groups with a pKa of 8 or less) is, for example, preferably 50 to 90 mass%, more preferably 60 to 90 mass%, and even more preferably 65 to 85 mass%. The content of components derived from styrene compounds, among vinyl compounds, is set in consideration of the above range, but is preferably 0 to 80 mass%, more preferably 10 to 50 mass%. The content of the constituent component having a functional group with a pKa of 8 or less is, for example, preferably 0 to 30 mass %, more preferably 0 to 20 mass %, and even more preferably 0.05 to 10 mass %. The content of the constituent component derived from the (meth)acrylic compound (M1) (excluding the constituent component having a functional group with a pKa of 8 or less) may be less than 50 mass %, and for example, is preferably 0 to 40 mass %, and more preferably 0 to 30 mass %. The content of the constituent component derived from the macromonomer is preferably, for example, 0 to 30% by mass.

[0107] The linear polymer may have a substituent. The substituent is not particularly limited, but preferably includes a group selected from the following substituent Z.

[0108] The linear polymer can be synthesized by selecting raw material compounds by a known method according to the type of bond in the main chain, and subjecting the raw material compounds to polyaddition or condensation polymerization.

[0109] - Substituent Z - Alkyl groups (preferably alkyl groups having 1 to 20 carbon atoms, for example, methyl, ethyl, isopropyl, t-butyl, pentyl, heptyl, 1-ethylpentyl, benzyl, 2-ethoxyethyl, 1-carboxymethyl, etc.), alkenyl groups (preferably alkenyl groups having 2 to 20 carbon atoms, for example, vinyl, allyl, oleyl, etc.), alkynyl groups (preferably alkynyl groups having 2 to 20 carbon atoms, for example, ethynyl, butadiynyl, phenylethynyl, etc.), cycloalkyl groups (preferably cycloalkyl groups having 3 to 20 carbon atoms, for example, cyclopropyl, cyclopentyl, etc.), cyclohexyl, 4-methylcyclohexyl, etc. In the present invention, the term "alkyl group" generally includes a cycloalkyl group, but will be described separately here.), aryl groups (preferably aryl groups having 6 to 26 carbon atoms, for example, phenyl, 1-naphthyl, 4-methoxyphenyl, 2-chlorophenyl, 3-methylphenyl, etc.), aralkyl groups (preferably aralkyl groups having 7 to 23 carbon atoms, for example, benzyl, phenethyl, etc.), heterocyclic groups (preferably heterocyclic groups having 2 to 20 carbon atoms, more preferably at least one oxygen atom, sulfur atom, nitrogen atom, etc.), The heterocyclic group includes an aromatic heterocyclic group and an aliphatic heterocyclic group. Examples of the heterocyclic group include a tetrahydropyran ring group, a tetrahydrofuran ring group, 2-pyridyl, 4-pyridyl, 2-imidazolyl, 2-benzimidazolyl, 2-thiazolyl, 2-oxazolyl, a pyrrolidone group, etc.), an alkoxy group (preferably an alkoxy group having 1 to 20 carbon atoms, for example, methoxy, ethoxy, isopropyloxy, benzyloxy, etc.), an aryloxy group (preferably an aryloxy group having 6 to 26 carbon atoms, for example, phenoxy, 1-naphthyloxy, etc.), and the like. oxy, 3-methylphenoxy, 4-methoxyphenoxy, etc.), heterocyclic oxy groups (groups in which an -O- group is bonded to the above heterocyclic group), alkoxycarbonyl groups (preferably alkoxycarbonyl groups having 2 to 20 carbon atoms, for example, ethoxycarbonyl, 2-ethylhexyloxycarbonyl, dodecyloxycarbonyl, etc.), aryloxycarbonyl groups (preferably aryloxycarbonyl groups having 6 to 26 carbon atoms, for example, phenoxycarbonyl, 1-naphthyloxycarbonyl, 3-methylphenoxycarbonyl, 4-methoxyphenoxycarbonyl, etc.),Heterocyclic oxycarbonyl groups (groups in which an -O-CO- group is bonded to the above heterocyclic group), amino groups (preferably containing an amino group having 0 to 20 carbon atoms, an alkylamino group, or an arylamino group, for example, amino (-NH2), N,N-dimethylamino, N,N-diethylamino, N-ethylamino, anilino, etc.), sulfamoyl groups (preferably containing a sulfamoyl group having 0 to 20 carbon atoms, for example, N,N-dimethylsulfamoyl, N-phenylsulfamoyl, etc.), acyl groups (alkylcarbonyl groups, alkenylcarbonyl groups, alkynylcarbonyl groups, arylcarbonyl groups, etc.), and heterocyclic carbonyl groups, preferably acyl groups having 1 to 20 carbon atoms, such as acetyl, propionyl, butyryl, octanoyl, hexadecanoyl, acryloyl, methacryloyl, crotonoyl, benzoyl, naphthoyl, and nicotinoyl; acyloxy groups (including alkylcarbonyloxy groups, alkenylcarbonyloxy groups, alkynylcarbonyloxy groups, and heterocyclic carbonyloxy groups, preferably acyloxy groups having 1 to 20 carbon atoms, such as acetyloxy, propionyloxy, butyryloxy, octanoyloxy, and hexadecanoyl); Examples of such groups include aryloxy groups (preferably aryloxy groups having 7 to 23 carbon atoms, such as benzoyloxy and naphthoyloxy), aryloxy groups (preferably aryloxy groups having 7 to 23 carbon atoms, such as benzoyloxy and naphthoyloxy), carbamoyl groups (preferably carbamoyl groups having 1 to 20 carbon atoms, such as N,N-dimethylcarbamoyl and N-phenylcarbamoyl), acylamino groups (preferably acylamino groups having 1 to 20 carbon atoms, such as acetylamino and benzoylamino), alkylthio groups (preferably alkylthio groups having 1 to 20 carbon atoms, such as benzoyloxy and naphthoyloxy), and alkylthio groups (preferably alkylthio groups having 1 to 20 carbon atoms). an arylthio group (preferably an arylthio group having 6 to 26 carbon atoms, for example, phenylthio, 1-naphthylthio, 3-methylphenylthio, 4-methoxyphenylthio), a heterocyclic thio group (a group in which an -S- group is bonded to the above heterocyclic group), an alkylsulfonyl group (preferably an alkylsulfonyl group having 1 to 20 carbon atoms, for example, methylsulfonyl, ethylsulfonyl), an arylsulfonyl group (preferably an arylsulfonyl group having 6 to 22 carbon atoms, for example, benzenesulfonyl),Alkylsilyl groups (preferably alkylsilyl groups having 1 to 20 carbon atoms, for example, monomethylsilyl, dimethylsilyl, trimethylsilyl, triethylsilyl, etc.), arylsilyl groups (preferably arylsilyl groups having 6 to 42 carbon atoms, for example, triphenylsilyl, etc.), alkoxysilyl groups (preferably alkoxysilyl groups having 1 to 20 carbon atoms, for example, monomethoxysilyl, dimethoxysilyl, trimethoxysilyl, triethoxysilyl, etc.), aryloxysilyl groups (preferably aryloxysilyl groups having 6 to 42 carbon atoms, for example, triphenyloxysilyl, etc.), phosphoryl groups (preferably phosphate groups having 0 to 20 carbon atoms, for example, -OP(=O)(R, P )2), a phosphonyl group (preferably a phosphonyl group having 0 to 20 carbon atoms, for example, —P(═O)(R P )2), a phosphinyl group (preferably a phosphinyl group having 0 to 20 carbon atoms, for example, —P(R P )2), a phosphonic acid group (preferably a phosphonic acid group having 0 to 20 carbon atoms, for example, —PO(OR P ) 2), sulfo group (sulfonic acid group), carboxy group, hydroxy group, sulfanyl group, cyano group, halogen atom (e.g., fluorine atom, chlorine atom, bromine atom, iodine atom, etc.). P is a hydrogen atom or a substituent (preferably a group selected from the substituent Z). Furthermore, each of the groups listed as the substituent Z may be further substituted with the above-mentioned substituent Z. The alkyl group, alkylene group, alkenyl group, alkenylene group, alkynyl group and / or alkynylene group may be cyclic or chain-like, and may be straight-chain or branched.

[0110] Specific examples of linear polymers include the polymers shown below in addition to those synthesized in the examples, but the present invention is not limited to these. In the specific examples below, the contents of the constituent components are appropriately set taking into consideration the radius of gyration α, the SP value, etc.

[0111] [ka]

[0112] The polymer binder may contain one or more linear polymers. The polymer binder may also contain other polymers, etc., as long as the effect of the linear polymer is not impaired. As the other polymers, polymers that are commonly used as binders for all-solid-state secondary batteries can be used without any particular limitation.

[0113] The electrode composition may contain one or more types of binder. The content of the binder in the electrode composition is not particularly limited, but is preferably 0.05 to 8.0 mass%, more preferably 0.1 to 6.0 mass%, even more preferably 0.2 to 4.0 mass%, and particularly preferably 0.2 to 1.0 mass%, from the viewpoints of improving dispersibility, suppressing a decrease in ionic conductivity, and further strengthening the binding of solid particles. For the same reasons, the content of the binder in 100 mass% of the solids content of the electrode composition is preferably 0.1 to 10.0 mass%, more preferably 0.2 to 8 mass%, even more preferably 0.3 to 6.0 mass%, and particularly preferably 0.3 to 1.0 mass%. In the present invention, at 100% by mass of solid content, the mass ratio of the combined mass (total amount) of the inorganic solid electrolyte and the active material to the mass of the polymer binder [(mass of inorganic solid electrolyte + mass of active material) / (total mass of polymer binder)] is preferably in the range of 1,000 to 1. This ratio is more preferably 500 to 2, and even more preferably 100 to 10.

[0114] <Dispersion medium> The electrode composition of the present invention contains a dispersion medium that disperses or dissolves the above-mentioned components. Such a dispersion medium may be any organic compound that is liquid in the environment of use, and examples thereof include various organic solvents, specifically alcohol compounds, ether compounds, amide compounds, amine compounds, ketone compounds, aromatic compounds, aliphatic compounds, nitrile compounds, ester compounds, etc. The dispersion medium may be a non-polar dispersion medium (hydrophobic dispersion medium) or a polar dispersion medium (hydrophilic dispersion medium), but a non-polar dispersion medium is preferred in that it can exhibit excellent dispersibility. A non-polar dispersion medium generally refers to a medium with low affinity for water, and in the present invention, examples of the non-polar dispersion medium include ester compounds, ketone compounds, ether compounds, aromatic compounds, and aliphatic compounds.

[0115] Examples of alcohol compounds include methyl alcohol, ethyl alcohol, 1-propyl alcohol, 2-propyl alcohol, 2-butanol, ethylene glycol, propylene glycol, glycerin, 1,6-hexanediol, cyclohexanediol, sorbitol, xylitol, 2-methyl-2,4-pentanediol, 1,3-butanediol, and 1,4-butanediol.

[0116] Examples of the ether compound 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, dioxane (including 1,2-, 1,3-, and 1,4-isomers), etc.).

[0117] Examples of the amide compound include N,N-dimethylformamide, N-methyl-2-pyrrolidone, 2-pyrrolidinone, 1,3-dimethyl-2-imidazolidinone, ε-caprolactam, formamide, N-methylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, N-methylpropanamide, and hexamethylphosphoric triamide.

[0118] Examples of the amine compound include triethylamine, diisopropylethylamine, and tributylamine. 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), isobutyl propyl ketone, sec-butyl propyl ketone, pentyl propyl ketone, and butyl propyl ketone. Examples of aromatic compounds include benzene, toluene, xylene, and perfluorotoluene. Examples of aliphatic compounds include hexane, heptane, octane, nonane, decane, dodecane, cyclohexane, methylcyclohexane, ethylcyclohexane, cycloheptane, cyclooctane, decalin, paraffin, gasoline, naphtha, kerosene, and diesel. Examples of the nitrile compound include acetonitrile, propionitrile, and isobutyronitrile. Examples of the ester compound include ethyl acetate, propyl acetate, butyl acetate, ethyl butyrate, propyl butyrate, isopropyl butyrate, butyl butyrate, isobutyl butyrate, butyl pentanoate, pentyl pentanoate, ethyl isobutyrate, propyl isobutyrate, isopropyl isobutyrate, isobutyl isobutyrate, propyl pivalate, isopropyl pivalate, butyl pivalate, and isobutyl pivalate.

[0119] In the present invention, among these, ether compounds, ketone compounds, aromatic compounds, aliphatic compounds, and ester compounds are preferred, and ester compounds, ketone compounds, aromatic compounds, and ether compounds are more preferred.

[0120] The number of carbon atoms in the compound constituting the dispersion medium is not particularly limited, and is preferably 2 to 30, more preferably 4 to 20, even more preferably 6 to 15, and particularly preferably 7 to 12.

[0121] The dispersion medium is characterized by, for example, the SP value (unit: MPa) in terms of the dispersibility of solid particles. 1 / 2 ) is preferably 14 to 24, more preferably 15 to 22, and even more preferably 17 to 20. The difference (absolute value) in the SP value between the dispersion medium and the linear polymer is not particularly limited and can be, for example, 7.0 or less, but is preferably 3 or less, more preferably 0 to 2, and even more preferably 0 to 1, in that the molecular chain of the linear polymer spreads in the dispersion medium, improving its own dispersibility and thereby further improving the dispersibility of the solid particles. The SP value of the dispersion medium is calculated by the Hoy method described above, and is expressed in units of MPa. 1 / 2 The SP value is a value converted into a mass fraction. When an electrode composition contains two or more dispersion media, the SP value of the dispersion media means the SP value of the dispersion media as a whole, and is the sum of the products of the SP values ​​of each dispersion media and their mass fractions. Specifically, the SP value is calculated in the same manner as the SP value of the polymer described above, except that the SP value of each dispersion media is used instead of the SP value of the constituent components. The SP values ​​(units omitted) of major dispersion media are shown below. MIBK (18.4), diisopropyl ether (16.8), dibutyl ether (17.9), diisopropyl 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)

[0122] The boiling point of the dispersion medium at normal pressure (1 atmosphere) is preferably 50° C. or higher, more preferably 70° C. or higher. The upper limit is preferably 250° C. or lower, more preferably 220° C. or lower.

[0123] The electrode composition of the present invention may contain one or more dispersion media, such as a mixed xylene (a mixture of o-xylene, p-xylene, m-xylene, and ethylbenzene). In the present invention, the content of the dispersion medium in the electrode composition is not particularly limited and can be set appropriately, for example, preferably 10 to 80 mass %, more preferably 30 to 70 mass %, and particularly preferably 40 to 60 mass % in the electrode composition. The electrode composition of the present invention contains an inorganic solid electrolyte, an active material, and a polymer binder that satisfy the above relationship, and therefore can achieve a high solids concentration (reduce the content of the dispersion medium) without impairing dispersibility, etc. For example, the content of the dispersion medium in the electrode composition can be 40% by mass or less, and can be reduced to 30% by mass or less. In practice, the lower limit of the content is 5% by mass or more, and preferably 10% by mass or more. An electrode composition with such an increased solids concentration can form a thick active material layer suitable for achieving high energy density.

[0124] <Conductive additive> The electrode composition of the present invention preferably contains a conductive auxiliary agent. For example, the silicon atom-containing active material as the negative electrode active material is preferably used in combination with a conductive auxiliary agent. The conductive additive is not particularly limited, and may be any of those known as general conductive additives. For example, it may be an electron conductive material, such as graphites (e.g., natural graphite, artificial graphite), carbon blacks (e.g., acetylene black, ketjen black, furnace black), amorphous carbon (e.g., needle coke), carbon fibers (e.g., vapor-grown carbon fiber, carbon nanotube), carbonaceous materials (e.g., graphene, fullerene), metal powders (e.g., copper, nickel), metal fibers, or conductive polymers (e.g., polyaniline, polypyrrole, polythiophene, polyacetylene, polyphenylene derivatives). In the present invention, when an active material and a conductive additive are used in combination, the conductive additive is one among the above-mentioned conductive additives that does not insert or release ions of metals belonging to Group 1 or Group 2 of the periodic table (preferably Li ions) when the battery is charged and discharged, and does not function as an active material. Therefore, among conductive additives, one that can function as an active material in the active material layer when the battery is charged and discharged is classified as an active material rather than a conductive additive. Whether or not a conductive additive functions as an active material when the battery is charged and discharged is not uniquely determined, but is determined by the combination with the active material.

[0125] The conductive assistant contained in the electrode composition of the present invention may be one type or two or more types. The shape of the conductive additive is not particularly limited, but a particulate shape is preferred. When the electrode composition of the present invention contains a conductive auxiliary, the content of the conductive auxiliary in the electrode composition is preferably 0 to 10 mass %, more preferably 0 to 5 mass %, based on 100 mass % of the solid content.

[0126] <Lithium salt> The electrode composition of the present invention also preferably contains a lithium salt (supporting electrolyte). The lithium salt is preferably a lithium salt that is usually used in this type of product, and is not particularly limited. For example, the lithium salts described in paragraphs 0082 to 0085 of JP-A No. 2015-088486 are preferred. When the electrode composition of the present invention contains a lithium salt, the content of the lithium salt is preferably 0.1 parts by mass or more, more preferably 5 parts by mass or more, relative to 100 parts by mass of the solid electrolyte, and the upper limit is preferably 50 parts by mass or less, more preferably 20 parts by mass or less.

[0127] <Dispersant> The electrode composition of the present invention may contain no dispersant other than the polymer binder because the polymer binder also functions as a dispersant. However, the dispersant may contain a dispersant. The dispersant may be selected from those typically used in all-solid-state secondary batteries. Generally, compounds intended for particle adsorption and steric and / or electrostatic repulsion are preferably used.

[0128] <Other additives> The electrode composition of the present invention may contain, as appropriate, other components in addition to the above components, such as an ionic liquid, a thickener, a polymerization initiator (such as one that generates an acid or radical by heat or light), an antifoaming agent, a leveling agent, a dehydrating agent, and an antioxidant. The ionic liquid is contained to further improve ionic conductivity, and any known ionic liquid can be used without particular limitation. The electrode composition may also contain a polymer other than the linear polymer described above, a commonly used binder, and the like.

[0129] (Preparation of electrode composition) The electrode composition of the present invention can be prepared as a mixture, preferably as a slurry, by mixing an inorganic solid electrolyte, an active material, the above-mentioned polymer binder, a dispersion medium, preferably a conductive aid, and further optionally a lithium salt and other optional components, for example, in any of various commonly used mixers. The mixing method is not particularly limited, and can be performed using a known mixer such as a ball mill, bead mill, planetary mixer, blade mixer, roll mill, kneader, disk mill, planetary mixer, narrow gap disperser, etc. The components may be mixed all at once or sequentially. The mixing environment is not particularly limited, and examples include dry air or an inert gas. The mixing conditions are also not particularly limited, and can be set appropriately.

[0130] [Electrode sheet for all-solid-state secondary batteries] The electrode sheet for an all-solid-state secondary battery of the present invention (sometimes simply referred to as an electrode sheet) is a sheet-like molded article that can form an active material layer or an electrode (a laminate of an active material layer and a current collector) of an all-solid-state secondary battery, and includes various embodiments depending on its application. The electrode sheet of the present invention has an active material layer formed from the electrode composition of the present invention on the surface of a substrate. Therefore, the electrode sheet of the present invention has an active material layer with a uniform thickness and a predetermined shape, even when produced industrially using a highly productive roll-to-roll method. This electrode sheet is used as the active material layer of an all-solid-state secondary battery, and when a current collector is used as the substrate, as an electrode of the all-solid-state secondary battery.

[0131] The electrode sheet of the present invention may be any electrode sheet having an active material layer on the surface of a substrate. The electrode sheet may include an embodiment having a substrate, an active material layer, and a solid electrolyte layer in this order, as well as an embodiment having a substrate, an active material layer, a solid electrolyte layer, and an active material layer in this order. The electrode sheet may have other layers in addition to the above-described layers. Examples of other layers include a protective layer (release sheet), a coating layer, and the like.

[0132] The substrate is not particularly limited as long as it can support the active material layer, and examples thereof include sheets (plates) of materials described below for the current collector, organic materials, inorganic materials, etc. Examples of organic materials include various polymers, specifically polyethylene terephthalate, polypropylene, polyethylene, cellulose, etc. Examples of inorganic materials include glass, ceramics, etc.

[0133] 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 is preferably the same as the content of each component in the solid content 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 of each layer described in the all-solid-state secondary battery described below. In the present invention, each layer constituting the sheet for an all-solid-state secondary battery may have a single-layer structure or a multi-layer structure. The solid electrolyte layer, and further the active material layer when not formed from the electrode composition of the present invention, are formed from ordinary constituent layer forming materials.

[0134] In the electrode sheet of the present invention, the active material layer on the surface of the substrate is formed from the electrode composition of the present invention. Therefore, by using the electrode sheet of the present invention as the active material layer of an all-solid-state secondary battery, or as an electrode of an all-solid-state secondary battery when a current collector is used as the substrate, an all-solid-state secondary battery exhibiting high ionic conductivity (low resistance) can be realized. The electrode sheet for an all-solid-state secondary battery of the present invention has an active material layer with a uniform thickness and a predetermined shape, even when produced industrially, for example, by a highly productive roll-to-roll process. Furthermore, the electrode sheet for an all-solid-state secondary battery of the present invention can be used as is (without cutting off the edges of the sheet-like body) as an electrode for an all-solid-state secondary battery. Using this electrode sheet for an all-solid-state secondary battery as an electrode contributes to the production of all-solid-state secondary batteries with high ionic conductivity and low resistance, particularly in industrial production, while reducing production costs. Therefore, the electrode sheet for an all-solid-state secondary battery of the present invention is suitable for use as a sheet capable of forming an electrode for an all-solid-state secondary battery. In the present invention, the active material layer with a uniform thickness and a predetermined shape is an active material layer formed while suppressing the occurrence of dripping and uneven application of the electrode composition, and can be evaluated as described in the examples.

[0135] [Method of manufacturing electrode sheets for all-solid-state secondary batteries] The method for producing the electrode sheet for an all-solid-state secondary battery of the present invention is not particularly limited, and examples include a method in which the electrode composition of the present invention is coated and dried on the surface of a substrate (optionally via another layer) to form a layer (coated and dried layer) composed of the electrode composition. This allows the production of a sheet having a substrate and a coated and dried layer. Here, the term "coated and dried 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 having a composition obtained by removing the dispersion medium from the electrode composition of the present invention). The coated and dried layer or the active material layer composed of the coated and dried layer may contain residual dispersion medium as long as it does not impair the effects of the present invention. The residual amount can be, for example, 3 mass % or less in each layer. In the method for producing an electrode sheet for an all-solid-state secondary battery of the present invention, each step such as coating and drying will be described in the method for producing an all-solid-state secondary battery below.

[0136] In this way, it is possible to produce an electrode sheet for an all-solid-state secondary battery having an active material layer made of a coated and dried layer, or an active material layer produced by appropriately pressurizing the coated and dried layer, etc. The pressurizing conditions for the coated and dried layer will be described later in the method for producing an all-solid-state secondary battery. In addition, in the method for producing a sheet for an all-solid-state secondary battery of the present invention, the substrate, protective layer (particularly the release sheet), etc. can also be peeled off.

[0137] [All-solid-state secondary battery] The all-solid-state secondary battery of the present invention has a positive electrode active material layer, a negative electrode active material layer facing 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 not particularly limited in other configuration as long as it has a solid electrolyte layer between the positive electrode active material layer and the negative electrode active material layer, and for example, a known configuration related to all-solid-state secondary batteries can be adopted. The positive electrode active material layer is preferably formed on a positive electrode current collector and constitutes a positive electrode. The negative electrode active material layer is preferably formed on a negative electrode current collector and constitutes a negative electrode.

[0138] At least one of the negative electrode active material layer and the positive electrode active material layer is preferably formed from the electrode composition of the present invention, and the negative electrode active material layer and the positive electrode active material layer are preferably formed from 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 from the electrode composition of the present invention, exhibits high ionic conductivity (low resistance) and can extract a large current, even when produced by an industrially advantageous roll-to-roll method. The active material layer formed from the electrode composition of the present invention preferably has the same component types and contents as those in the solid content of the electrode composition of the present invention. When the active material layer or the solid electrolyte layer is not formed from the electrode composition of the present invention, known materials can be used. In the present invention, each of the constituent layers (including the current collector, etc.) that constitute the all-solid-state secondary battery may have a single-layer structure or a multi-layer structure.

[0139] <Positive Electrode Active Material Layer and Negative Electrode Active Material Layer> The thickness of the negative electrode active material layer and the positive electrode active material layer is not particularly limited. Taking into consideration the dimensions of a typical all-solid-state secondary battery, the thickness of each layer is preferably 10 to 1,000 μm, and more preferably 20 μm or more and less than 500 μm. In the all-solid-state secondary battery of the present invention, it is further preferable that the thickness of at least one of the positive electrode active material layer and the negative electrode active material layer is 50 μm or more and less than 500 μm. The active material layer having the above thickness may be a single layer (one application of the electrode composition) or a multilayer (multiple applications of the electrode composition), but from the viewpoints of resistance reduction and productivity, it is preferable to form a single active material layer having a large layer thickness using the electrode composition of the present invention, which can be formed into a thick layer. The layer thickness of the thick single active material layer that can be preferably formed using the electrode composition of the present invention can be, for example, 70 μm or more, and can also be 100 μm or more. <Solid electrolyte layer> The solid electrolyte layer is formed using a known material capable of forming a solid electrolyte layer of an all-solid-state secondary battery. The thickness is not particularly limited, but is preferably 10 to 1,000 μm, and more preferably 20 μm or more and less than 500 μm.

[0140] <Current collector> The positive electrode active material layer and the negative electrode active material layer may each have a current collector on the side opposite to the solid electrolyte layer, and such positive electrode current collector and negative electrode current collector are preferably made of an electron conductor. In the present invention, either the positive electrode current collector or the negative electrode current collector, or both of them together, may be simply referred to as current collectors. As the material for forming the positive electrode current collector, aluminum, aluminum alloy, stainless steel, nickel, titanium, etc., as well as aluminum or stainless steel surface treated with carbon, nickel, titanium or silver (thin film formed), are preferred, and among these, aluminum and aluminum alloy are more preferred. As the material for forming the negative electrode current collector, aluminum, copper, a copper alloy, stainless steel, nickel, titanium, etc., as well as aluminum, copper, a copper alloy, or stainless steel whose surface is treated with carbon, nickel, titanium, or silver are preferred, and aluminum, copper, a copper alloy, and stainless steel are more preferred.

[0141] The collector is usually in the form of a film sheet, but it is also possible to use a net, a punched material, a lath material, a porous material, a foam material, a molded material of a group of fibers, or the like. The thickness of the current collector is not particularly limited, but is preferably 1 to 500 μm. It is also preferable to make the surface of the current collector uneven by surface treatment.

[0142] <Other configurations> In the present invention, a functional layer or member may be appropriately interposed or disposed between or on the outside of each of the negative electrode current collector, negative electrode active material layer, solid electrolyte layer, positive electrode active material layer, and positive electrode current collector.

[0143] <Case> Depending on the application, the all-solid-state secondary battery of the present invention may be used as an all-solid-state secondary battery with the above structure as it is, but it is preferable to further encapsulate it in an appropriate casing to make it into a dry battery. The casing may be made of metal or resin (plastic). When a metallic casing is used, for example, an aluminum alloy or stainless steel may be used. It is preferable that the metallic casing is divided into a positive electrode casing and a negative electrode casing, and that the positive electrode current collector and the negative electrode current collector are electrically connected, respectively. It is preferable that the positive electrode casing and the negative electrode casing are joined and integrated via a gasket to prevent short circuits.

[0144] An all-solid-state secondary battery according to a preferred embodiment of the present invention will be described below with reference to FIG. 1, but the present invention is not limited thereto.

[0145] FIG. 1 is a cross-sectional view showing a schematic diagram of an all-solid-state secondary battery (lithium ion secondary battery) according to a preferred embodiment of the present invention. The all-solid-state secondary battery 10 of this embodiment has, as viewed from the negative electrode side, 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, in this order. Each layer is in contact with each other and has an adjacent structure. By adopting such a structure, electrons (e - ) is supplied to the battery, and lithium ions (Li + On the other hand, during discharge, the lithium ions (Li + ) is returned to the positive electrode side, and electrons are supplied to the operating part 6. In the illustrated example, a light bulb is used as a model for the operating part 6, and it is lit by the discharge.

[0146] When an all-solid-state secondary battery having the layer structure shown in FIG. 1 is placed in a 2032-type coin case, this all-solid-state secondary battery is referred to as a laminate 12 for an all-solid-state secondary battery, and a battery produced by placing this laminate 12 for an all-solid-state secondary battery in a 2032-type coin case 11 (for example, a coin-type all-solid-state secondary battery shown in FIG. 2) is sometimes referred to as an all-solid-state secondary battery 13.

[0147] (solid electrolyte layer) The solid electrolyte layer may be any of those used in conventional all-solid-state secondary batteries without any particular limitations. This solid electrolyte layer contains an inorganic solid electrolyte having ionic conductivity of a metal belonging to Group 1 or 2 of the periodic table, and the optional components described above within the range that does not impair the effects of the present invention, and usually does not contain an active material.

[0148] (Positive electrode active material layer and negative electrode active material layer) In the all-solid-state secondary battery 10, both the positive electrode active material layer and the negative electrode active material layer are formed of the electrode composition of the present invention. Preferably, the positive electrode, in which a positive electrode active material layer and a positive electrode current collector are laminated, and the negative electrode, in which a negative electrode active material layer and a negative electrode current collector are laminated, are formed of the electrode sheet of the present invention, in which the current collector is used as a substrate. The positive electrode active material layer contains an inorganic solid electrolyte having ionic conductivity of a metal belonging to Group 1 or 2 of the periodic table, a positive electrode active material, a polymer binder, and the above-mentioned optional components and the like within the scope of not impairing the effects of the present invention. The negative electrode active material layer contains an inorganic solid electrolyte having ionic conductivity of a metal belonging to Group 1 or 2 of the periodic table, a negative electrode active material, a polymer binder, and the above-mentioned optional components within the scope of not impairing 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 the lithium metal layer include a layer formed by depositing or molding lithium metal powder, lithium foil, and a lithium vapor-deposited film. The thickness of the lithium metal layer can be, for example, 1 to 500 μm, regardless of the thickness of the negative electrode active material layer.

[0149] 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 may be the same or different from one another.

[0150] In the present invention, when the active material layer is formed from the electrode composition of the present invention, an all-solid-state secondary battery exhibiting high ionic conductivity (low resistance) can be realized even when produced by the industrially advantageous roll-to-roll method.

[0151] (current collector) The positive electrode current collector 5 and the negative electrode current collector 1 are as described above.

[0152] [Manufacturing all-solid-state secondary batteries] The all-solid-state secondary battery can be produced by a conventional method. Specifically, the all-solid-state secondary battery can be produced by forming at least one active material layer using the electrode composition of the present invention, and then forming a solid electrolyte layer and, as appropriate, the other active material layer or electrode using a known material.

[0153] The all-solid-state secondary battery of the present invention can be produced by a method (a method for producing an electrode sheet for an all-solid-state secondary battery of the present invention) that includes (intervenes through) a step of applying the electrode composition of the present invention to the surface of a substrate (for example, a metal foil that will become a current collector) and drying to form (produce) a coating film. For example, a cathode sheet for an all-solid-state secondary battery is produced by depositing an electrode composition containing a cathode active material as a cathode material (cathode composition) on a metal foil cathode current collector to form a cathode active material layer. Next, a solid electrolyte composition for forming a solid electrolyte layer is deposited on the cathode active material layer to form a solid electrolyte layer. Furthermore, an electrode composition containing a negative electrode active material as a negative electrode material (negative electrode composition) is deposited on the solid electrolyte layer to form a negative electrode active material layer. By overlaying 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 a solid electrolyte layer is sandwiched between a cathode active material layer and a negative electrode active material layer can be obtained. This can also be enclosed in a housing to form a desired all-solid-state secondary battery. Alternatively, the method for forming each layer may be reversed, and an all-solid-state secondary battery may be produced by forming an anode active material layer, a solid electrolyte layer, and a cathode active material layer on an anode current collector, and then stacking the anode current collector on top of the anode active material layer, a solid electrolyte layer, and a cathode current collector on top of the anode active material layer.

[0154] Another method is as follows. That is, a positive electrode sheet for an all-solid-state secondary battery is produced as described above. Furthermore, an electrode composition containing a negative electrode active material as a negative electrode material (negative electrode composition) is formed as a film on a metal foil serving as a negative electrode current collector to form a negative electrode active material layer, thereby producing a negative electrode sheet for an all-solid-state secondary battery. Next, a solid electrolyte layer is formed on the active material layer of either of these sheets as described above. Furthermore, the other of the positive electrode sheet for an all-solid-state secondary battery and the negative electrode sheet for an all-solid-state secondary battery is laminated on the solid electrolyte layer so that the solid electrolyte layer and the active material layer are in contact with each other. In this manner, an all-solid-state secondary battery can be produced. Another method is as follows. That is, a positive electrode sheet for an all-solid-state secondary battery and a negative electrode sheet for an all-solid-state secondary battery are prepared as described above. Separately, an inorganic solid electrolyte-containing composition is formed into a film on a substrate to prepare a solid electrolyte sheet for an all-solid-state secondary battery comprising a solid electrolyte layer. Furthermore, the positive electrode sheet for an all-solid-state secondary battery and the negative electrode sheet for an all-solid-state secondary battery are laminated so as to sandwich the solid electrolyte layer peeled from the substrate. In this way, an all-solid-state secondary battery can be produced.

[0155] In yet another method, a positive electrode sheet for an all-solid-state secondary battery 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 prepared as described above. Next, the positive electrode sheet for an all-solid-state secondary battery or the negative electrode sheet for an all-solid-state secondary battery and the solid electrolyte sheet for an all-solid-state secondary battery are stacked together with the positive electrode active material layer or the negative electrode active material layer in contact with the solid electrolyte layer, and pressurized. In this way, the solid electrolyte layer is transferred to the positive electrode sheet for an all-solid-state secondary battery or the negative electrode sheet for an all-solid-state secondary battery. Thereafter, the solid electrolyte layer from which the substrate of the solid electrolyte sheet for an all-solid-state secondary battery has been peeled is stacked with the negative electrode sheet for an all-solid-state secondary battery or the positive electrode sheet for an all-solid-state secondary battery (with the negative electrode active material layer or the positive electrode active material layer in contact with the solid electrolyte layer) and pressurized. In this way, an all-solid-state secondary battery can be produced. The pressurization method and pressurization conditions in this method are not particularly limited, and the method and pressurization conditions described in the pressurization step below can be applied.

[0156] The active material layer or the like can be formed, for example, by pressurizing the electrode composition or the like on the substrate or the active material layer under pressure conditions to be described later, or a sheet molded body can also be used. In the above manufacturing method, the electrode composition of the present invention may be used for either the positive electrode composition or the negative electrode composition, and the electrode composition of the present invention may be used for both the positive electrode composition and the negative electrode composition. When the active material layer is formed using a composition other than the electrode composition of the present invention, examples of the material include commonly used compositions, etc. Alternatively, instead of forming a negative electrode active material layer during the production of an all-solid-state secondary battery, the negative electrode active material layer can be formed by bonding ions of a metal belonging to Group 1 or Group 2 of the periodic table, which have accumulated in the negative electrode current collector during initialization or charging during use (described later), with electrons and depositing the metal on the negative electrode current collector, etc.

[0157] <Formation of each layer (film formation)> The method for applying each composition is not particularly limited and can be appropriately selected, and examples thereof include coating (preferably wet coating), spray coating, spin coating, dip coating, slit coating, stripe coating, and bar coating. The coated composition is preferably subjected to a drying treatment (heat treatment). The drying treatment may be performed after each coating of the composition or after multi-layer coating. The drying temperature is not particularly limited, and is, for example, preferably 30°C or higher, more preferably 60°C or higher, and even more preferably 80°C or higher. The upper limit is not particularly limited, but is preferably 300°C or lower, more preferably 250°C or lower, and even more preferably 200°C or lower. Heating within this temperature range can remove the dispersion medium and create a solid state (coated, dried layer). In addition, it is preferable not to raise the temperature too high, as this avoids damaging the components of the all-solid-state secondary battery. This allows the all-solid-state secondary battery to exhibit excellent overall performance and obtain good ionic conductivity.

[0158] After applying each composition, after stacking the constituent layers, or after fabricating the all-solid-state secondary battery, it is preferable to pressurize each layer or the all-solid-state secondary battery. Examples of a pressurizing method include a hydraulic cylinder press. The pressure is not particularly limited, and is generally preferably in the range of 5 to 1500 MPa. The applied compositions may be heated simultaneously with the pressing. The heating temperature is not particularly limited and is generally in the range of 30 to 300°C. Pressing may also be carried out at a temperature higher than the glass transition temperature of the inorganic solid electrolyte. Pressing may also be carried out at a temperature higher than the glass transition temperature of the polymer contained in the polymer binder. However, the temperature is generally not higher than the melting point of the polymer. The pressure may be applied after the application solvent or dispersion medium has been dried in advance, or may be applied while the solvent or dispersion medium remains. The compositions may be applied simultaneously, or coating, drying and pressing may be carried out simultaneously and / or sequentially. After being applied to separate substrates, the compositions may be laminated by transfer.

[0159] The atmosphere in the film-forming method (coating, drying, and pressurization (under heating)) is not particularly limited, and may be any of the atmosphere, dry air (dew point -20°C or lower), and inert gas (e.g., argon gas, helium gas, and nitrogen gas). The pressing time may be short (for example, within a few hours) and high pressure may be applied, or long (for example, one day or more) and moderate pressure may be applied. In the case of an all-solid-state secondary battery other than an electrode sheet for an all-solid-state secondary battery, for example, a restraining device for the all-solid-state secondary battery (such as a screw tightening pressure) may be used to continuously apply moderate pressure. The pressing pressure may be uniform or may vary with respect to the pressed portion such as the sheet surface. The pressure can be varied depending on the area or thickness of the pressed portion, or the same portion can be subjected to different pressures in stages. The press surface may be smooth or roughened.

[0160] In the present invention, the formation of each of the above-mentioned layers, particularly the formation of a film of the electrode composition of the present invention, can be carried out by a so-called batch method using a sheet-like substrate, but can also be carried out by a roll-to-roll method, which is one of the most productive industrial production methods. Furthermore, the active material layer used in the production of an all-solid-state secondary battery may be prepared by cutting out an electrode sheet for an all-solid-state secondary battery, punching, or the like, but it is preferable to use the produced sheet for an all-solid-state secondary battery as is in terms of productivity and reduction of production costs.

[0161] <Initialization> The all-solid-state secondary battery produced as described above is preferably initialized after production or before use. The initialization is not particularly limited, and can be performed, for example, by carrying out initial charge and discharge under an elevated pressure, and then releasing the pressure until the pressure reaches the general operating pressure of an all-solid-state secondary battery.

[0162] [Applications of all-solid-state secondary batteries] The all-solid-state secondary battery of the present invention can be used in a variety of applications. While there are no particular limitations on the application, examples of applications include electronic devices such as notebook computers, pen-input PCs, mobile PCs, electronic book players, mobile phones, cordless phone handsets, pagers, handheld terminals, portable fax machines, portable copiers, portable printers, headphone stereos, video camcorders, LCD televisions, handheld vacuum cleaners, portable CD players, mini-discs, electric shavers, transceivers, electronic organizers, calculators, memory cards, portable tape recorders, radios, and backup power supplies. Other consumer applications include automobiles (e.g., electric vehicles), electric vehicles, motors, lighting fixtures, toys, game consoles, road conditioners, clocks, flash devices, cameras, and medical devices (e.g., pacemakers, hearing aids, and shoulder massagers). Furthermore, the battery can be used for various military and space applications. It can also be combined with solar cells. [Example]

[0163] The present invention will be described in more detail below based on examples, but the present invention should not be construed as being limited thereto. In the following examples, "parts" and "%" representing compositions are based on mass unless otherwise specified. In the present invention, "room temperature" means 25°C.

[0164] 1. Polymer synthesis and preparation of binder solution or dispersion Each polymer shown in Table 1 and having the chemical formula given below was synthesized as follows. [Synthesis Example S-1: Synthesis of Polymer S-1 and Preparation of Binder Solution S-1] To a 100 mL measuring cylinder, 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 Industries, Ltd.), and 0.36 g of polymerization initiator V-601 (trade name, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were added and dissolved in 36.0 g of butyl butyrate to prepare a monomer solution. 18.0 g of butyl butyrate was added to a 300 mL three-neck flask and stirred at 80°C, to which the above monomer solution was added dropwise over 2 hours. After the dropwise addition was completed, the temperature was raised to 90°C and stirring continued for 2 hours. The resulting polymerization solution was poured into 480 g of a water / acetone mixed solvent (70 / 30 weight ratio), stirred for 10 minutes, and then allowed to stand for 10 minutes. The supernatant was removed, and the resulting precipitate was dissolved in 80 g of butyl butyrate. The mixture was heated at 30 hPa and 60°C for 1 hour to distill off the methanol. In this way, polymer S-1 (a (meth)acrylic polymer of a random copolymer) was synthesized, and a binder solution S-1 (concentration: 38% by mass) consisting of polymer S-1 was obtained.

[0165] [Synthesis Example S-2: Synthesis of Polymer S-2 and Preparation of Binder Solution S-2] An autoclave was charged with 100 parts by mass of ion-exchanged water, 65 parts by mass of vinylidene fluoride, 20 parts by mass of hexafluoropropene, and 15 parts by mass of tetrafluoroethylene, and then 1 part by mass of a polymerization initiator, Peroyl IPP (trade name, chemical name: diisopropyl peroxydicarbonate, manufactured by NOF Corporation), 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 was added to 10 parts by mass of the obtained polymer to dissolve it. In this way, polymer S-2 (a fluorine-based polymer of a random copolymer) was synthesized, and a binder solution S-2 (concentration 6.3% by mass) consisting of polymer S-2 was obtained.

[0166] [Synthesis Example S-3: Synthesis of Polymer S-3 and Preparation of Binder Solution S-3] An autoclave was charged with 100 parts by mass of ion-exchanged water, 70 parts by mass of vinylidene fluoride, and 30 parts by mass of hexafluoropropene, and then 1 part by mass of a polymerization initiator, Perloyl IPP (trade name, chemical name: diisopropyl peroxydicarbonate, manufactured by NOF Corporation), 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 mass of butyl butyrate was added to 10 parts by mass of the obtained polymer to dissolve it. In this way, polymer S-3 (a fluorine-based polymer of a random copolymer) was synthesized, and a binder solution S-3 (concentration: 20% by mass) consisting of polymer S-3 was obtained.

[0167] [Synthesis Example S-4: Synthesis of Polymer S-4 and Preparation of Binder Solution S-4] To a 100 mL measuring cylinder, 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 Industries Co., Ltd.) were added, and the mixture was dissolved in 36.0 g of butyl butyrate to prepare a monomer solution. 18.0 g of butyl butyrate was added to a 300 mL three-necked flask and stirred at 80° C., to which the monomer solution was added dropwise over 2 hours. After completion of the dropwise addition, the temperature was raised to 90° C. and the mixture was stirred for 2 hours. In this way, polymer S-4 (a (meth)acrylic polymer of a random copolymer) was synthesized, and a binder solution S-4 (concentration: 40% by mass) consisting of polymer S-4 was obtained.

[0168] [Synthesis Example S-5: Synthesis of Polymer S-5 and Preparation of Binder Solution S-5] Polymer S-5 was synthesized in the same manner as in Synthesis Example S-1, except that in Synthesis Example S-1, compounds that lead to each component were used so that polymer S-5 had the composition (content of the component) shown in Table 1, and the amount of V-601 added was changed to 1.08 g, and binder solution S-5 consisting of this polymer was obtained. [Synthesis Example S-6: Synthesis of Polymer S-6 and Preparation of Binder Solution S-6] Polymer S-6 was synthesized in the same manner as in Synthesis Example S-1, except that in Synthesis Example S-1, compounds that lead to each component were used so that polymer S-6 would have the composition (content of the component) shown in Table 1, and the amount of V-601 added was changed to 3.16 g, and binder solution S-6 consisting of this polymer was obtained.

[0169] [Synthesis Examples S-7 and S-8: Synthesis of Polymers S-7 and S-8, and Preparation of Binder Solutions S-7 and S-8] Polymers S-7 and S-8 were synthesized in the same manner as in Synthesis Example S-1, except that compounds were used to derive the respective constituent components so that polymers S-7 and S-8 had the compositions (contents of the constituent components) shown in Table 1, and binder solutions S-7 and S-8 composed of the respective polymers were obtained, respectively.

[0170] [Synthesis Example S-9: Synthesis of Polymer S-9 and Preparation of Binder Solution S-9] Polymer S-9 was synthesized in the same manner as in Synthesis Example S-6, except that in Synthesis Example S-6, compounds were used that lead to each component so that polymer S-9 had the composition shown in Table 1 (types and contents of components), and a binder solution S-9 consisting of this polymer was obtained. [Synthesis Example S-10: Synthesis of Polymer S-10 and Preparation of Binder Solution S-10] Polymer S-10 was synthesized in the same manner as in Synthesis Example S-2, except that the amount of perloyl IPP added was changed to 0.1 parts by mass, and a binder solution S-10 consisting of this polymer was obtained.

[0171] [Synthesis Example S-11: Synthesis of Polymer S-11 and Preparation of Binder Dispersion S-11] To a 100 mL measuring cylinder, 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 Industries, Ltd.) were added, and the mixture was dissolved in 36.0 g of butyl butyrate to prepare a monomer solution. 18.0 g of butyl butyrate was added to a 300 mL three-necked flask and stirred at 80° C., to which the monomer solution was added dropwise over 2 hours. After completion of the dropwise addition, the temperature was raised to 90° C. and the mixture was stirred for 2 hours. In this way, polymer S-11 (a random copolymer (meth)acrylic polymer) was synthesized, and a binder dispersion S-11 (concentration: 40% by mass) consisting of polymer S-11 was obtained. The average particle size of the binder in this dispersion was 140 nm.

[0172] [Synthesis Example T-1: Synthesis of Polymer T-1 and Preparation of Binder Solution T-1] Polymer T-1 was synthesized in the same manner as in Synthesis Example S-1, except that the amount of V-601 added was changed to 0.12 g, and a binder solution T-1 made of this polymer was obtained. [Synthesis Example T-2: Synthesis of Polymer T-2 and Preparation of Binder Solution T-2] Polymer T-2 was synthesized in the same manner as in Synthesis Example S-2, except that the amount of Perloyl IPP added in Synthesis Example S-2 was changed to 0.8 parts by mass, and a binder solution T-2 consisting of this polymer was obtained.

[0173] [Synthesis Example T-3: Synthesis of Polymer T-3 and Preparation of Binder Solution T-3] Polymer T-3 was synthesized in the same manner as in Synthesis Example S-3, except that the amount of Perloyl IPP added was changed to 0.3 parts by mass, and a binder solution T-3 consisting of this polymer was obtained. [Synthesis Example T-4: Synthesis of Polymer T-4 and Preparation of Binder Solution T-4] Polymer T-4 was synthesized in the same manner as in Synthesis Example S-4, except that the amount of V-601 added was changed to 0.32 g, and a binder solution T-4 made of this polymer was obtained.

[0174] [Synthesis Example T-5: Synthesis of Polymer T-5 and Preparation of Binder Solution T-5] Polymer T-5 was synthesized in the same manner as in Synthesis Example S-5, except that the amount of V-601 added was changed to 1.20 g, and a binder solution T-5 made of this polymer was obtained. [Synthesis Example T-6: Synthesis of Polymer T-6 and Preparation of Binder Solution T-6] Polymer T-6 was synthesized in the same manner as in Synthesis Example S-6, except that the amount of V-601 added was changed to 3.30 g, and a binder solution T-6 made of this polymer was obtained.

[0175] [Synthesis Example T-7: Synthesis of Polymer T-7 and Preparation of Binder Dispersion T-7] To a 100 mL measuring cylinder, 38.8 g of dodecyl acrylate (Tokyo Chemical Industry Co., Ltd.), 0.80 g of maleic acid (Fujifilm Wako Pure Chemical Industries, Ltd.), 0.40 g of poly(ethylene glycol) diacrylate (Aldrich Chemicals) and 0.36 g of polymerization initiator V-601 (trade name, Fujifilm Wako Pure Chemical Industries, Ltd.) were added and dissolved in 40.0 g of butyl butyrate to prepare a monomer solution. 20.0 g of butyl butyrate was added to a 300 mL three-necked flask and stirred at 80° C. The monomer solution was added dropwise over 2 hours. After the dropwise addition was completed, the mixture was stirred at 80° C. for 2 hours, then heated to 90° C. and stirred for 2 hours. In this way, polymer T-7 (crosslinked (meth)acrylic polymer of random copolymer) was synthesized. This polymer T-7 was not soluble in butyl butyrate, and a binder consisting of polymer T-7 was obtained as dispersion T-7 (concentration 40% by mass). The average particle diameter of the binder in this dispersion was 180 nm.

[0176] [Preparation Example T-8: Preparation of Binder Solution T-8] Polymer T-8 was a polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP polymer, manufactured by Almacare, mass average molecular weight 100,000). Polymer T-8 was dissolved in butyl butyrate to prepare a binder solution T-8 with a concentration of 10% by mass.

[0177] The composition, mass average molecular weight, radius of gyration α and SP value (MPa) of each polymer synthesized 1 / 2 ) are shown in Table 1. The mass average molecular weight, radius of gyration α and SP value (MPa 1 / 2 ) were measured by the above-mentioned methods. For polymers S-2, S-3, S-10, T-2, T-3, and T-8, the compounds that lead to the constituent components that make up the fluorine-based polymer are listed in the "Constituent M1" column using " / ". Since the composition of polymer T-8 is unknown, it is shown with "-" in the "Content" and "SP value" columns. The "S" and "T" attached to the above polymer numbers more clearly indicate that the polymer is primarily used in the electrode compositions of the Examples or Comparative Examples, and have no other meaning.

[0178] The synthesized polymers are shown below. The content (mass %) of each component is shown in Table 1. [ka]

[0179] [Table 1]

[0180] In the table, "-" in the component column indicates that the corresponding component is not contained. The compounds from which each constituent component is derived are explained below. The SP values ​​in the following compounds are values ​​when the compounds are made into constituent components (homopolymers). - Component M1 - LA: Dodecyl acrylate (SP value: 18.8 MPa) 1 / 2 , manufactured by Tokyo Chemical Industry Co., Ltd.) EA: Ethyl acrylate (SP value: 20.1 MPa) 1 / 2 , manufactured by Tokyo Chemical Industry Co., Ltd.) LMA: Dodecyl methacrylate (SP value: 18.5 MPa) 1 / 2 , manufactured by Tokyo Chemical Industry Co., Ltd.) VDF: Polyvinylidene fluoride (SP value: 13.1 MPa) 1 / 2 , manufactured by Shinquest) HFP: Hexafluoropropylene (SP value: 9.4 MPa) 1 / 2 , manufactured by Shinquest) TFE: Tetrafluoroethylene (SP value: 10.1 MPa) 1 / 2 , manufactured by Shinquest) - Component M2 - The component M2 represents a component having a functional group with a pKa of 8 or less. Maleic acid: (SP value: 22.2 MPa 1 / 2 , Fujifilm Wako Pure Chemical Industries, Ltd.) Monoisopropyl fumarate: (SP value: 20.3 MPa 1 / 2 , manufactured by Tokyo Chemical Industry Co., Ltd.) 4-Hydroxystyrene: (SP value: 21.9 MPa 1 / 2 , manufactured by Tokyo Chemical Industry Co., Ltd.) MAEHP: Mono-2-(methacryloyloxy)ethyl phthalate (SP value: 21.4 MPa) 1 / 2 , manufactured by Tokyo Chemical Industry Co., Ltd.) AEHS: Mono(2-acryloyloxyethyl) succinate (SP value: 21.8 MPa) 1 / 2 , manufactured by Tokyo Chemical Industry Co., Ltd.)

[0181] - Constituent M3 - Component M3 represents a component that does not correspond to either component M1 or M2. HEA: Hydroxyethyl acrylate (SP value: 25.9 MPa) 1 / 2 , manufactured by Tokyo Chemical Industry Co., Ltd.) PEGDA700: Poly(ethylene glycol) diacrylate (number average molecular weight 700, SP value: 21.7 MPa) 1 / 2 , manufactured by Aldrich)

[0182] 2. Synthesis of sulfide-based inorganic solid electrolyte [Synthesis Example L-1: Median diameter D S1-50 Synthesis of 60 nm inorganic solid electrolyte LPS1] The sulfide-based inorganic solid electrolyte was synthesized with reference to the non-patent literature of T. Ohtomo, A. Hayashi, M. Tatsumisago, Y. Tsuchida, S. Hama, K. Kawamoto, Journal of Power Sources, 233, (2013), pp. 231-235, and A. Hayashi, S. Hama, H. Morimoto, M. Tatsumisago, T. Minami, Chem. Lett., (2001), pp. 872-873. Specifically, in a glove box under an argon atmosphere (dew point -70°C), 2.42 g of lithium sulfide (Li2S, Aldrich, purity >99.98%) and 3.90 g of diphosphorus pentasulfide (P2S5, Aldrich, purity >99%) were weighed out, placed in an agate mortar, and mixed for 5 minutes using an agate pestle. The molar ratio of Li2S to P2S5 was Li2S:P2S5 = 75:25. Next, 66 g of 5 mm diameter zirconia beads were placed in a 45 mL zirconia container (manufactured by Fritsch), and the entire lithium sulfide and diphosphorus pentasulfide mixture was added. The container was then completely sealed under an argon atmosphere. The container was then placed in a planetary ball mill P-7 (trade name, manufactured by Fritsch) and mechanically milled at 25°C and 700 rpm for 48 hours to obtain 6.20 g of a yellow sulfide-based inorganic solid electrolyte powder (Li-PS-based glass, hereinafter sometimes referred to as LPS). Thus, the median diameter DS1-50 We synthesized an inorganic solid electrolyte LPS1 with a thickness of 60 nm.

[0183] [Synthesis Example L-2: Median diameter D S2-50 Synthesis of inorganic solid electrolyte LPS2 with a diameter of 1500 nm In Synthesis Example L-1, the median diameter D S1-50 synthesized a 1500 nm inorganic solid electrolyte LPS2.

[0184] [Synthesis Example L-3: Median diameter D S3-50 Synthesis of inorganic solid electrolyte LPS3 with a 2900 nm In Synthesis Example L-1, the median diameter D S1-50 We synthesized an inorganic solid electrolyte LPS3 with a molecular weight of 2900 nm.

[0185] [Synthesis Example L-4: Median diameter D S4-50 Synthesis of inorganic solid electrolyte LPS4 with a wavelength of 4200 nm In Synthesis Example L-1, the median diameter D S1-50 synthesized an inorganic solid electrolyte LPS4 with a diameter of 4200 nm.

[0186] 3. NMC:LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 Preparation of O2 (Lithium Nickel Manganese Cobalt Oxide) [Synthesis Example C-1: Median diameter D AC-50 Synthesis of NMC1 with 55 nm Sodium hydroxide and ammonia were continuously added to an aqueous solution (1 mol / L) of nickel sulfate, cobalt sulfate, and manganese sulfate at 60°C to adjust the pH to 11.3, and a metal composite hydroxide was prepared by coprecipitation, consisting of a solid solution of nickel, manganese, and cobalt in a molar ratio of 33:33:33. This metal composite hydroxide and lithium carbonate were weighed so that the ratio of the total number of moles of metals other than Li (Ni, Co, Mn) to the number of moles of Li was 1:1, and then thoroughly mixed. The mixture was heated at a rate of 5°C / min and pre-baked in an air atmosphere at 750°C for 2 hours, then heated at a rate of 3°C / min and pre-baked at 850°C for 10 hours. The mixture was then cooled to room temperature and the median diameter D AC-50 synthesized 55 nm of NMC1.

[0187] [Synthesis Example C-2: Median diameter D AC-50 Synthesis of NMC2 with a molecular weight of 140 nm In Synthesis Example C-1, the median diameter D AC-50 synthesized 140 nm of NMC2. [Synthesis Example C-3: Median diameter D AC-50 Synthesis of 200 nm NMC3 In Synthesis Example C-1, the median diameter D AC-50 synthesized 200 nm of NMC3. [Synthesis Example C-4: Median diameter D AC-50 Synthesis of NMC4 at 1700 nm] In Synthesis Example C-1, the median diameter D AC-50 synthesized NMC4 at 1700 nm. [Synthesis Example C-5: Median diameter D AC-50 Synthesis of NMC5 at 2000 nm In Synthesis Example C-1, the median diameter D AC-50 synthesized 2000 nm of NMC5. [Synthesis Example C-6: Median diameter DAC-50 Synthesis of NMC6 at 2500 nm In Synthesis Example C-1, the median diameter D AC-50 synthesized NMC6 at 2500 nm.

[0188] [Synthesis Example C-7: Median diameter D AC-50 Synthesis of NMC7 at 2600 nm] In Synthesis Example C-1, the median diameter D AC-50 synthesized NMC7 at 2600 nm. [Synthesis Example C-8: Median diameter D AC-50 Synthesis of NMC8 at 4000 nm In Synthesis Example C-1, the median diameter D AC-50 synthesized NMC8 at 4000 nm. [Synthesis Example C-9: Median diameter D AC-50 Synthesis of NMC9 at 4600 nm] In Synthesis Example C-1, the median diameter D AC-50 synthesized NMC9 with a wavelength of 4600 nm. [Synthesis Example C-10: Median diameter D AC-50 Synthesis of NMC10 at 5000 nm In Synthesis Example C-1, the median diameter D AC-50 synthesized 5000 nm NMC10. [Synthesis Example C-11: Median diameter D AC-50 Synthesis of NMC11 at 5300 nm] In Synthesis Example C-1, the median diameter D AC-50 synthesized NMC11 with an emission wavelength of 5300 nm.

[0189] 4. Silicon (Si) Preparation Silicon 1: Median diameter D AA-50 = 55 nm (Aldrich) Silicon 2: Median diameter D AA-50 = 200 nm (Silgrain MicronCut, manufactured by Elkem) Silicon 3: Median diameter D AA-50 = 350 nm (Silgrain MicronCut, manufactured by Elkem) Silicon 4: Median diameter D AA-50 =2000nm (NER Japan) Silicon 5: Median diameter D AA-50 =2400nm (NER Japan) Silicon 6: Median diameter D AA-50 =2800nm ​​(NER Japan) Silicon 7: Median diameter D AA-50 =3000nm (NER Japan) Silicon 8: Median diameter D AA-50 =4000nm (NER Japan) Silicon 9: Median diameter D AA-50 =5000nm (IPROS) Silicon 10: Median diameter D AA-50 =5300nm (NER Japan)

[0190] [Example 1] Each of the compositions shown in Tables 2-1 to 2-4 (collectively referred to as Table 2) was prepared as follows.

[0191] <Preparation of Positive Electrode Composition> 60 g of zirconia beads with a diameter of 5 mm were placed in a 45 mL zirconia container (manufactured by Fritsch), and 10.2 g of LPS synthesized in each of the above Synthesis Examples L shown in the "Inorganic Solid Electrolyte" column of Table 2-1 and 13 g (total amount) of butyl butyrate as a dispersion medium were added. This container was placed in a Fritsch planetary ball mill P-7 (trade name) and stirred at 25°C at a rotation speed of 200 pm for 30 minutes. Thereafter, 25.9 g of NMC as the positive electrode active material shown in the "Positive electrode active material" column of Table 2-2, which was synthesized in each of Synthesis Examples C above, 0.74 g of acetylene black (AB) as a conductive additive, and 0.19 g (solid content mass) of the binder solution or dispersion shown in the "Binder solution or dispersion" column of Table 2-1 were added to the container, and the container was set in a planetary ball mill P-7. Mixing was continued for 30 minutes at a temperature of 25°C and a rotation speed of 200 rpm, to prepare positive electrode compositions (slurries) PK-1 to PK-14 and PKc21 to PKc31, respectively.

[0192] <Preparation of negative electrode composition> 60 g of zirconia beads with a diameter of 5 mm were placed in a 45 mL zirconia container (manufactured by Fritsch), and 11.4 g of LPS synthesized in each Synthesis Example L shown in the "Inorganic Solid Electrolyte" column of Table 2-3, 0.13 g (solid content by mass) of the binder solution or dispersion shown in the "Binder Solution or Dispersion" column of Table 2-3, and 25.0 g (total amount) of butyl butyrate were added. This container was placed in a Fritsch planetary ball mill P-7 (trade name), and mixing was carried out for 60 minutes at a temperature of 25°C and a rotation speed of 300 pm. Thereafter, 12.5 g of silicon (Si) as the negative electrode active material shown in the "Negative electrode active material" column of Table 2-4 prepared as described above and 1.0 g of VGCF (manufactured by Showa Denko K.K.) as a conductive additive were added, and similarly, the container was set in a planetary ball mill P-7 and mixed at a temperature of 25°C and a rotation speed of 100 rpm for 10 minutes to prepare negative electrode compositions (slurries) NK-1 to NK-17 and NKc21 to NKc31, respectively.

[0193] For each of the prepared compositions, the viscosity (cP), the median diameter D of the inorganic solid electrolyte and the active material S-50 (nm) and D A-50 (nm), as well as the mass average molecular weight, radius of gyration α, and SP value (MPa1 / 2 ), adsorption rate A AM The median diameter D of the inorganic solid electrolyte and the active material contained in each composition is shown in Table 2. 50 Calculate using the above method and add "D 50 The SP values ​​of each polymer and the dispersion medium (the SP value of butyl butyrate is 18.6 MPa) are shown in the " column (units are omitted in the table). 1 / 2 The difference (absolute value) between the SP value and the pKa value was calculated, and is shown in the "SP value difference" and "pKa" columns of Table 2. The viscosity (cP) of the composition, as well as the median diameter (nm), mass average molecular weight, radius of gyration α, and SP value (MPa 1 / 2 ) was measured or calculated by the above method. AM (%) was measured by the following method (units are omitted in the table). In Table 2, the composition content is the content (mass%) relative to the total mass of the composition, and the solid content is the content (mass%) relative to 100% by mass of the solid content of the composition, and units are omitted in the table. The SP values ​​and SP value differences shown in Table 2 are in MPa. 1 / 2 The unit of the adsorption rate is mass %, but this is omitted in Table 2. In each composition, the polymer binders consisting of polymers S-1 to S-10, T-1 to T-6, and T-8 were dissolved in the dispersion medium, and the binders consisting of polymers S-11 and T-7 were dispersed in the dispersion medium in particulate form.

[0194] [Adsorption rate A of binder to active material AM Measurement of The adsorption rate A was measured using the active material, polymer binder, and dispersion medium used in the preparation of each electrode composition shown in Table 2. AM was measured. That is, a binder solution with a concentration of 1% by mass was prepared by dissolving the polymer binder in a dispersion medium (butyl butyrate). Polymers S-11 and T-7 were prepared as binder dispersions with a concentration of 1% by mass. The binder solution or dispersion and the active material were placed in a 15 mL vial, with the mass ratio of the polymer binder to the active material in the binder solution or dispersion being 42:1. The mixture was stirred at room temperature at 80 rpm using a mixer rotor for 1 hour, and then allowed to stand. The supernatant obtained by solid-liquid separation was filtered through a filter with a pore size of 1 μm, and the entire filtrate was dried to solid. The mass of the polymer binder remaining in the filtrate (the mass of the polymer binder not adsorbed to the active material) W A The mass W A and the mass W of the polymer binder contained in the binder solution used for the measurement B From the following formula, the adsorption rate A of the polymer binder to the active material is calculated. AM (% by mass) was calculated. Adsorption rate A of polymer binder AM is the average value of the adsorption rate obtained by performing the above measurement twice. Adsorption rate A AM (%)=[(W B -W A ) / W B ] x 100 The adsorption rate A was measured using the active material and polymer binder extracted from the formed active material layer and the dispersion medium used in preparing the electrode composition. AM When measured, similar values ​​were obtained.

[0195] [Table 2-1]

[0196] [Table 2-2]

[0197] [Table 2-3]

[0198] [Table 2-4]

[0199] LPS1 to LPS4: LPS1 to LPS4 synthesized in Synthesis Examples L-1 to L-4 NMC1 to NMC11: NMC1 to NMC11 synthesized in Synthesis Examples C-1 to C-10 Si1 to Si10: Silicon 1 to Silicon 10 prepared as described above AB: Acetylene black VGCF: Carbon nanotubes

[0200] <Preparation of positive electrode sheet for all-solid-state secondary battery> Each of the positive electrode compositions shown in the "Electrode Composition No." column in Table 3 obtained above was applied to a 20 μm-thick aluminum foil using a Baker-type applicator (product name: SA-201, manufactured by Tester Sangyo Co., Ltd.), heated at 80°C for 1 hour, and then heated at 110°C for 1 hour to dry the positive electrode composition (removing the dispersion medium). Thereafter, using a heat press, the dried positive electrode composition was pressed (10 MPa, 1 minute) at 25°C to produce positive electrode sheets for all-solid-state secondary batteries (referred to as positive electrode sheets in Table 3) 101 to 114 and c11 to c21, each having a positive electrode active material layer with a thickness of 120 μm.

[0201] <Preparation of negative electrode sheet for all-solid-state secondary battery> Each of the negative electrode compositions shown in the "Electrode composition No." column in Table 3 obtained above was applied to a copper foil having a thickness of 20 μm using a Baker-type applicator (product name: SA-201), heated at 80°C for 1 hour, and then heated at 110°C for 1 hour to dry the negative electrode composition (removing the dispersion medium). Thereafter, using a heat press, the dried negative electrode composition was pressed (10 MPa, 1 minute) at 25°C to produce negative electrode sheets for all-solid-state secondary batteries (referred to as negative electrode sheets in Table 3) 115 to 131 and c22 to c32, each having a negative electrode active material layer with a thickness of 110 μm.

[0202] <Evaluation 1: Coating unevenness test> The active material layer of each of the prepared all-solid-state secondary battery positive electrode sheets and all-solid-state secondary battery negative electrode sheets (length: 50 mm × width: 20 mm) was peeled from the substrate (aluminum foil or copper foil), and then a test piece TP measuring 10 mm × 10 mm was cut out from approximately the center of the width direction of this active material layer. Note that for each active material layer, the test piece TP was cut out at the same position in the longitudinal direction, avoiding both ends in the longitudinal direction. For this test piece TP, the layer thickness was measured at five points using a constant pressure thickness measuring instrument (manufactured by Teclock Corporation), and the arithmetic mean value Y of the layer thickness was calculated. The occurrence of coating unevenness was evaluated by applying the largest deviation value (maximum deviation value) among the deviation values ​​(%) obtained from each measurement value and its arithmetic mean value Y using the following formula (a) or (b) to the following evaluation criteria. In this test, the smaller the maximum deviation value (%), the more uniform the layer thickness of the active material layer, i.e., the more effectively the occurrence of coating unevenness of the electrode composition can be suppressed. In this test, an evaluation criterion of "D" or higher is considered a pass level. Formula (a): 100 × (maximum value of the layer thickness at five points - arithmetic mean value Y) / (arithmetic mean value Y) Formula (b): 100 × (arithmetic mean value Y − minimum value of layer thickness at 5 points) / (arithmetic mean value Y) The layer thickness was measured at the following five points: A to E for each test piece TP. First, as shown in FIG. 4, three imaginary lines y1, y2, and y3 are drawn to divide the test piece TP into four equal parts in the vertical direction. Then, three imaginary lines x1, x2, and x3 are drawn to divide the test piece TP into four equal parts in the horizontal direction in the same way, thereby dividing the surface of the test piece TP into a grid pattern. The measurement points are intersection A between virtual lines x1 and y1, intersection B between virtual lines x1 and y3, intersection C between virtual lines x2 and y2, intersection D between virtual lines x3 and y1, and intersection E between virtual lines x3 and y3. - Evaluation Criteria - A: Maximum deviation value < 1% B: 1%≦Maximum deviation value< 3% C: 3%≦Maximum deviation value< 5% D: 5%≦Maximum deviation value<10% E: 10%≦Maximum deviation value<20% F: 20%≦Maximum deviation value

[0203] <Evaluation 2: Dripping test (shape retention properties)> For each of the remaining active material layers cut out from the test piece TP used for the layer thickness measurement in the above <Evaluation 1: Coating Unevenness Test>, the layer thicknesses X1 and X2 were measured using a constant pressure thickness measuring device (manufactured by Teclock Corporation) at measurement points (two points) 2 mm inward from each of the two widthwise edges in the direction perpendicular to these edges. Note that for each active material layer, the measurement points were located at the same position in the vertical direction, avoiding both vertical edges. The thickness ratios (X1 / Y and X2 / Y) of the layer thickness X1 or X2 to the "arithmetic mean value Y of the layer thickness" in the above <Evaluation 1: Coating Unevenness Test> were calculated, and the average value (X / Y) was applied to the following evaluation criteria to evaluate the occurrence of dripping. In this test, a smaller average value of the thickness ratio indicates a more uniform layer thickness in the width direction of the active material layer, i.e., the more effectively the occurrence of dripping of the electrode composition can be suppressed. In this test, an evaluation criterion of "D" or higher is considered a pass level. - Evaluation Criteria - A: 0.95≦Average thickness ratio (X / Y) B: 0.90≦Average thickness ratio (X / Y)<0.95 C: 0.85≦Average thickness ratio (X / Y)<0.90 D: 0.80≦Average thickness ratio (X / Y)<0.85 E: 0.70≦Average thickness ratio (X / Y)<0.80 F: Average thickness ratio (X / Y)<0.70

[0204] [Table 3]

[0205] <Manufacturing all-solid-state secondary batteries> First, a positive electrode sheet for an all-solid-state secondary battery having a solid electrolyte layer and a negative electrode sheet for an all-solid-state secondary battery having a solid electrolyte layer were produced, both of which were to be used in the production of an all-solid-state secondary battery.

[0206] - Fabrication of a cathode sheet with a solid electrolyte layer for all-solid-state secondary batteries - Onto the positive electrode active material layer of each positive electrode sheet for an all-solid-state secondary battery shown in the "Electrode active material layer (sheet No.)" column in Table 4, a solid electrolyte sheet K-1 for an all-solid-state secondary battery prepared by the following method was laid so that the solid electrolyte layer was in contact with the positive electrode active material layer, and after transferring (laminating) by applying a pressure of 50 MPa at 25°C using a press, a pressure of 600 MPa was applied at 25°C to prepare positive electrode sheets for an all-solid-state secondary battery 101 to 114 and c11 to c21 (positive electrode active material layer thickness 90 μm) each having a solid electrolyte layer with a thickness of 30 μm.

[0207] - Fabrication of a negative electrode sheet with a solid electrolyte layer for all-solid-state secondary batteries - Onto the negative electrode active material layer of each negative electrode sheet for an all-solid-state secondary battery shown in the "Electrode active material layer (sheet No.)" column in Table 4, a solid electrolyte sheet K-1 for an all-solid-state secondary battery prepared by the following method was laid so that the solid electrolyte layer was in contact with the negative electrode active material layer, and after transferring (laminating) by applying a pressure of 50 MPa at 25°C using a press, a pressure of 600 MPa was applied at 25°C to prepare negative electrode sheets for all-solid-state secondary batteries 115 to 131 and c22 to c32 (negative electrode active material layer thickness: 80 μm), each of which had a solid electrolyte layer with a thickness of 30 μm.

[0208] A solid electrolyte sheet for a solid secondary battery K-1 used for producing an electrode sheet for an all-solid secondary battery was prepared as follows. - Preparation of inorganic solid electrolyte-containing composition K-1 - A 45 mL zirconia container (manufactured by Fritsch) was charged with 60 g of zirconia beads with a diameter of 5 mm, and then charged with 8.4 g of the LPS synthesized in Synthesis Example L-2 above, 0.6 g (solids mass) of KYNAR FLEX 2500-20 (trade name, PVdF-HFP: polyvinylidene fluoride hexafluoropropylene copolymer, manufactured by Arkema), and 11 g of butyl butyrate as a dispersion medium. The container was then placed in a Fritsch planetary ball mill P-7 (trade name). Mixing was carried out for 10 minutes at 25°C and 150 rpm to prepare inorganic solid electrolyte-containing composition (slurry) K-1.

[0209] - Fabrication of solid electrolyte sheet K-1 for all-solid-state secondary batteries - The inorganic solid electrolyte-containing composition obtained above was applied to a 20 μm-thick aluminum foil using a Baker-type applicator (product name: SA-201, manufactured by Tester Sangyo Co., Ltd.) and heated at 80°C for 2 hours to dry the inorganic solid electrolyte-containing composition (remove the dispersion medium). The dried inorganic solid electrolyte-containing composition was then heated and pressed using a heat press at a temperature of 120°C and a pressure of 40 MPa for 10 seconds to produce a solid electrolyte sheet K-1 for an all-solid-state secondary battery. The film thickness of the solid electrolyte layer was 50 μm.

[0210] - Manufacturing of all-solid-state secondary batteries - Next, an all-solid-state secondary battery No. 101 having the layer structure shown in FIG. 1 was produced. The positive electrode sheet for all-solid-state secondary batteries No. 101 provided with the solid electrolyte layer obtained above (the aluminum foil of the solid electrolyte-containing sheet K-1 had been peeled off) was cut into a disk shape with a diameter of 14.5 mm and placed in a stainless steel 2032-type coin case 11 incorporating a spacer and a washer (not shown in FIG. 2), as shown in FIG. 2. Next, a lithium foil cut into a disk shape with a diameter of 15 mm was placed on top of the solid electrolyte layer. After that, stainless steel foil was further placed on top of that, and the 2032-type coin case 11 was crimped to produce the all-solid-state secondary battery No. 101 shown in FIG. 2. The all-solid-state secondary battery produced in this manner has the layer structure shown in FIG. 1 (where the lithium foil corresponds to the negative electrode active material layer 2 and the negative electrode current collector 1).

[0211] All solid state secondary batteries Nos. 102 to 114 and c101 to c111 were produced in the same manner as in the production of all solid state secondary battery No. 101, except that in the production of the all solid state secondary battery No. 101, positive electrode sheets for all solid state secondary batteries having a solid electrolyte layer, represented by the numbers shown in the "Electrode active material layer (sheet No.)" column in Table 4, were used instead of positive electrode sheet No. 101 for all solid state secondary batteries having a solid electrolyte layer.

[0212] Also, an all-solid-state secondary battery No. 115 having the layer structure shown in FIG. 1 was produced as follows. The solid electrolyte-containing negative electrode sheet No. 115 for an all-solid-state secondary battery obtained above (the aluminum foil of the solid electrolyte-containing sheet K-1 had been peeled off) was cut into a disk shape with a diameter of 14.5 mm and placed in a stainless steel 2032-type coin case 11 incorporating a spacer and a washer (not shown in FIG. 2 ) as shown in FIG. 2 . Next, a positive electrode sheet (positive electrode active material layer) punched out to a diameter of 14.0 mm from the positive electrode sheet for an all-solid-state secondary battery prepared below was placed on top of the solid electrolyte layer. A stainless steel foil (positive electrode current collector) was further placed on top of the positive electrode sheet to form an all-solid-state secondary battery laminate 12 (a laminate consisting of stainless steel foil-aluminum foil-positive electrode active material layer-solid electrolyte layer-negative electrode active material layer-copper foil). The 2032-type coin case 11 was then crimped to produce the all-solid-state secondary battery No. 115 shown in FIG. 2 .

[0213] A positive electrode sheet for a solid secondary battery used in the production of all-solid secondary battery No. 115 was prepared. - Preparation of positive electrode composition - A 45 mL zirconia container (manufactured by Fritsch) was charged with 180 zirconia beads with a diameter of 5 mm, and 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) as a solid content mass, and 22 g of butyl butyrate were added. The container was placed in a Fritsch planetary ball mill P-7 (trade name) and stirred at 25°C at 300 rpm for 60 minutes. Then, LiNi was added as a positive electrode active material. 1 / 3 Co 1 / 3 Mn 1 / 3 7.0 g of O2 (NMC) was added, and the container was similarly set in the planetary ball mill P-7, and mixing was continued for 5 minutes at 25°C and 100 rpm to prepare a positive electrode composition. - Fabrication of positive electrode sheets for solid secondary batteries - The positive electrode composition obtained above was applied to a 20 μm-thick aluminum foil (positive electrode current collector) using a Baker-type applicator (product name: SA-201, manufactured by Tester Sangyo Co., Ltd.), and heated at 100° C. for 2 hours to dry the positive electrode composition (remove the dispersion medium). Thereafter, using a heat press, the dried positive electrode composition was pressed (10 MPa, 1 minute) at 25° C. to produce a positive electrode sheet for an all-solid-state secondary battery having a positive electrode active material layer with a thickness of 80 μm.

[0214] All solid state secondary batteries Nos. 116 to 131 and c112 to c122 were produced in the same manner as in the production of all solid state secondary battery No. 115, except that in the production of the all solid state secondary battery No. 115, negative electrode sheets for all solid state secondary batteries having a solid electrolyte layer, represented by the numbers shown in the "Electrode active material layer (sheet No.)" column in Table 4, were used instead of negative electrode sheet No. 115 for all solid state secondary batteries having a solid electrolyte layer.

[0215] <Evaluation 3: Ionic conductivity measurement> The ionic conductivity of each of the manufactured all-solid-state secondary batteries was measured. Specifically, for each all-solid-state secondary battery, AC impedance was measured at a voltage amplitude of 5 mV and a frequency of 1 MHz to 1 Hz using a 1255B FREQUENCY RESPONSE ANALYZER (trade name, manufactured by SOLARTRON) in a thermostatic bath at 25°C. From this, the resistance in the layer thickness direction of the ionic conductivity measurement sample was determined, and the ionic conductivity was calculated using the following formula (1). Equation (1): Ionic conductivity σ (mS / cm) = 1000 × sample layer thickness (cm) / [resistance (Ω) × sample area (cm 2 )] In formula (1), the sample layer thickness is the value (total thickness of the solid electrolyte layer and the electrode active material layer) measured before placing the laminate 12 in the 2032-type coin case 11 and subtracted by the thickness of the current collector. The sample area is the area of ​​a disk-shaped sheet with a diameter of 14.5 mm. The obtained ionic conductivity σ was judged to fall within any of the following evaluation criteria. In this test, the ionic conductivity σ is evaluated as passing if it is "D" or higher. - Evaluation Criteria - A: 0.60≦σ B: 0.50≦σ<0.60 C: 0.40≦σ<0.50 D: 0.30≦σ<0.40 E:0.20≦σ<0.30 F: σ<0.20

[0216] [Table 4]

[0217] The results shown in Tables 3 and 4 reveal the following. Comparative electrode compositions PKc21 to PKc31 and NKc21 to NKc31, which do not satisfy the above relationship defined in the present invention, are unable to balance the suppression of coating unevenness, the suppression of dripping, and the improvement of ionic conductivity of all-solid-state secondary batteries. The same is true for comparative electrode compositions PKc29, PKc31, NKc29, and NKc31, which contain a polymer binder made of crosslinked polymer T-7. In contrast, 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 further satisfy the above relationship specified in the present invention, can suppress coating unevenness and dripping even when applied to a film formation method, and can form an active material layer of a predetermined shape with a uniform layer thickness. By using these electrode compositions to form an active material layer for an all-solid-state secondary battery, high ionic conductivity (low resistance) can be achieved for the resulting all-solid-state secondary battery. These results demonstrate that even if the solids concentration of the electrode composition of the present invention is increased or the coating amount of the electrode composition of the present invention is increased, coating unevenness and dripping can be suppressed, and an active material layer that can achieve high ionic conductivity can be formed.

[0218] While the present invention has been described in connection with embodiments thereof, we do not intend to limit our invention to any of the details of the description unless otherwise specified, and believe that the claims should be construed broadly without departing from the spirit and scope of the invention as set forth in the appended claims.

[0219] This application claims priority based on Japanese Patent Application No. 2020-177998, filed on October 23, 2020, the contents of which are incorporated herein by reference as part of the present specification. [Explanation of symbols]

[0220] 1 Negative electrode current collector 2 Negative electrode active material layer 3 Solid electrolyte layer 4 Cathode active material layer 5 Positive electrode current collector 6. Operating parts 10 All-solid-state secondary battery 11 2032 type coin case 12. Laminates for all-solid-state secondary batteries 13 Coin-type all-solid-state secondary battery TP test specimen

Claims

1. An electrode composition comprising an inorganic solid electrolyte having ion conductivity of a metal belonging to Group 1 or 2 of the periodic table, an active material, a polymer binder, and a dispersion medium, the polymer binder comprises a linear polymer, the radius of rotation α of the polymer binder in the dispersion medium, and the median diameter D of the inorganic solid electrolyte and the active material converted into a content ratio; ５０ The radius of rotation α is the x-axis, and the median diameter D ５０ In a Cartesian coordinate system with the y-axis at point A (50, 60), point B (178, 4600), point C (85, 4600), point D (12, 2000), and point E (12, 60), the electrode composition is located within a polygonal area (including the boundary line) with vertices at point A (50, 60), point B (178, 4600), point C (85, 4600), point D (12, 2000), and point E (12, 60).

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

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

4. 4. The electrode composition according to claim 1, wherein the linear polymer contains a component having a functional group with a pKa of 8 or less.

5. 5. The electrode composition according to claim 1, wherein the polymer binder is soluble in the dispersion medium.

6. 6. The electrode composition according to claim 1, wherein the active material contains silicon as a constituent element.

7. The electrode composition according to any one of claims 1 to 6, wherein the inorganic solid electrolyte is a sulfide-based inorganic solid electrolyte.

8. The SP value of the dispersion medium is 14 to 24 MPa. １／２ The electrode composition according to any one of claims 1 to 7,

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

10. An all-solid-state secondary battery comprising a positive electrode active material layer, a solid electrolyte layer, and a negative electrode active material layer in this order, An all-solid-state secondary battery, wherein at least one of the positive electrode active material layer and the negative electrode active material layer is a layer constituted by the electrode composition according to any one of claims 1 to 8.

11. A method for producing an electrode sheet for an all-solid-state secondary battery, comprising forming a film of the electrode composition according to any one of claims 1 to 8 on a surface of a substrate.

12. A method for producing an all-solid-state secondary battery, comprising producing an all-solid-state secondary battery through the method according to claim 11.

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