Electrode, battery, and method for manufacturing electrode

Abstract

The present application relates to an electrode, a battery, and a method for manufacturing an electrode. The electrode (10) includes a current collector (5) and an active material mixture layer (11). The active material mixture layer (11) is provided on the current collector (5) and includes first particles (3), second particles (6), first active material particles (1), and second active material particles (4). The active material mixture layer (11) includes a first mixture layer (12) provided on the current collector (5) and including the first particles (3) and the first active material particles (1), and a second mixture layer (13) provided on the first mixture layer (12) and including the second particles (6) and the second active material particles (4). In a cross-sectional view of the electrode (10), the active material mixture layer (11) has a boundary (11A) at which the first active material particles (1) and the second active material particles (4) are in contact in a discontinuous state at least in part.

Description

TECHNICAL FIELD

[0001] The present application relates to an electrode, a battery, and a method for manufacturing an electrode. BACKGROUND

[0002] In recent years, due to the weight reduction and wireless of electronic devices such as personal computers and mobile phones, development of secondary batteries that can be repeatedly used is required. In addition, in the field of automobiles such as electric vehicles or hybrid vehicles, development of secondary batteries with high capacity is also valued. As secondary batteries, there are nickel-cadmium batteries, nickel-hydrogen batteries, lead storage batteries, and lithium ion batteries, etc. Among them, there is an increasing trend in the demand for lithium ion batteries, which have characteristics such as light weight, high voltage, and high energy density.

[0003] A lithium ion battery includes a positive electrode layer, a negative electrode layer, and an electrolyte disposed therebetween, and as the electrolyte, for example, an electrolytic solution obtained by dissolving a supporting electrolyte such as lithium hexafluorophosphate in an organic solvent, or a solid electrolyte is used. Currently, widely popular lithium ion batteries have flammability because they use an electrolyte containing an organic solvent. Therefore, materials, structures, and systems for ensuring the safety of lithium ion batteries are required. On the contrary, it is considered that by using a non-flammable solid electrolyte as an electrolyte, it can be expected that the materials, structures, and systems of lithium ion batteries can be simplified, and the energy density can be increased, the manufacturing cost can be reduced, and the productivity can be improved. Hereinafter, a battery using a solid electrolyte will be referred to as "all-solid-state battery".

[0004] In order to achieve high capacity of all-solid-state batteries, efforts have been made to increase the density of active materials contained in the electrode. However, by increasing the density of active materials, performance degradation of the battery during charging and discharging can occur. For example, by swelling and shrinking of active material particles during charging and discharging, the contact between active material particles decreases, and thus the conductivity of ions and electrons decreases, resulting in performance degradation of the battery. In addition, if the internal stress of the electrode increases due to swelling and shrinking, internal short circuiting due to electrode cracking or buckling occurs, resulting in reduced electrode performance and safety of the battery.

[0005] In Patent Literature 1, an electrode having the following structure is disclosed: in order to solve the performance degradation caused by charging and discharging cycles, the active material layer of the electrode is made into a laminated structure, and active material layers having active material particles with different particle diameters in the thickness direction are laminated.

[0006] PRIOR ART DOCUMENTS

[0007] PATENT LITERATURE

[0008] Patent Literature 1: Japanese Patent Application Laid-Open No. 2006-210003 SUMMARY

[0009] An electrode of one embodiment of the present application includes a current collector and an active material mixture layer. The active material mixture layer includes a first mixture layer and a second mixture layer. The first mixture layer is positioned on the current collector and includes first particles and first active material particles. The second mixture layer is positioned on the first mixture layer and includes second particles and second active material particles. In a cross-sectional view of the electrode, the active material mixture layer has a boundary between the first mixture layer and the second mixture layer at which the first active material particles and the second active material particles are in contact in a discontinuous state in at least a part of the active material mixture layer.

[0010] A method for manufacturing an electrode of one embodiment of the present application includes forming a first mixture coating film on a current collector from a first mixture of first particles and first active material particles; deforming a surface of a part of the first active material particles in a surface portion of the first mixture coating film to form a flat surface by pressing the first mixture coating film; and forming a second mixture coating film on the first mixture coating film after the pressing from a second mixture of second particles and second active material particles. BRIEF DESCRIPTION OF DRAWINGS

[0011] Figure 1 is a schematic cross-sectional view of an electrode of an embodiment.

[0012] Figure 2 is a schematic cross-sectional view of a positive electrode of an embodiment.

[0013] Figure 3 is an enlarged cross-sectional view of a vicinity of a boundary between a first positive electrode mixture layer and a second positive electrode mixture layer of an embodiment.

[0014] Figure 4 is a schematic cross-sectional view of a full solid-state battery of an embodiment.

[0015] Figure 5 is a view for explaining a method for manufacturing a positive electrode of an embodiment.

[0016] Figure 6 is a cross-sectional SEM image of a positive electrode active material mixture layer in an example.

[0017] Figure 7 is a cross-sectional SEM image of a vicinity of a boundary between a first positive electrode mixture layer and a second positive electrode mixture layer in an example.

[0018] Figure 8 is an enlarged cross-sectional SEM image of a positive electrode active material mixture layer in an example.

[0019] Figure 9 Table 1 showing data measured from a cross-sectional SEM image of a positive electrode active material mixture layer in an example is shown.

[0020] Reference Signs

[0021] 1: first active material particle

[0022] 1A: deformed particle

[0023] 1B: undeformed particle

[0024] 1C, 23C, 33C: flat face

[0025] 3: first particle

[0026] 4: second active material particle

[0027] 5: current collector

[0028] 6: second particle

[0029] 10: electrode

[0030] 11: active material mixture layer

[0031] 11A, 20A, 30A: boundary

[0032] 12: first mixture layer

[0033] 13: second mixture layer

[0034] 20: positive active material mixture layer

[0035] 21: first positive mixture layer

[0036] 22: second positive mixture layer

[0037] 23: first positive active material particle

[0038] 23A: deformed positive active material particle

[0039] 23B: undeformed positive active material particle

[0040] 25, 28, 34, 37, 41: solid electrolyte

[0041] 26: second positive active material particle

[0042] 27: positive current collector

[0043] 30: negative active material mixture layer

[0044] 31: first negative mixture layer

[0045] 32: second negative mixture layer

[0046] 33: first negative active material particle

[0047] 33A: deformed negative electrode active material particle

[0048] 33B: non-deformed negative electrode active material particle

[0049] 35: second negative electrode active material particle

[0050] 36: negative electrode current collector

[0051] 40: solid electrolyte layer

[0052] 50: positive electrode

[0053] 60: negative electrode

[0054] 100: all-solid-state battery DETAILED DESCRIPTION

[0055] In the structure of Patent Document 1, performance deterioration caused by unevenness in expansion and shrinkage in the thickness direction of the active material layer can be inhibited to some extent, but sometimes particle shift of the active material particles occurs due to expansion and shrinkage, and particle junctions decrease. Due to the decrease in junctions between the active material particles, ion conduction and electron conduction are hindered, and electrode performance deteriorates.

[0056] The present application was achieved in view of the above-described problems, and provides an electrode and the like having excellent electrode performance by inhibiting deterioration of electrode performance.

[0057] (SUMMARY OF THE INVENTION)

[0058] A summary of one embodiment of the present application is as follows.

[0059] An electrode of one embodiment of the present application includes a current collector and an active material mixture layer. The active material mixture has a first mixture layer and a second mixture layer. The first mixture layer is positioned on the current collector and includes first particles and first active material particles. The second mixture layer is positioned on the first mixture layer and includes second particles and second active material particles. In a cross-sectional view of the electrode, the active material mixture layer has a boundary between the first mixture layer and the second mixture layer at which the first active material particles and the second active material particles are in discontinuous contact in at least a part of the active material mixture layer.

[0060] According to one embodiment of the present application, an electrode or the like having excellent electrode properties can be provided. Specifically, a contact portion of the first active material particles in the first binder layer and the second active material particles in the second binder layer is present at the boundary. Therefore, even if the first active material particles and the second active material particles move in the first binder layer and the second binder layer, respectively, due to expansion and shrinkage or the like, since they are present in the respective binder layers, expansion and shrinkage are difficult to synchronize, and the contact of the first active material particles and the second active material particles is easily maintained. Furthermore, since internal stress caused by expansion and shrinkage of the first active material particles and the second active material particles can be absorbed at the boundary, breakage and buckling of the electrode can be suppressed. Therefore, the electrode of the present embodiment has excellent electrode properties and high durability by suppressing deterioration of electrode properties even when charging and discharging is performed and when exposed to heat or the like.

[0061] In addition, for example, the first active material particles can include deformed particles having a flat surface facing the second binder layer at the boundary, and non-deformed particles having no flat surface.

[0062] Since a portion of the first binder layer is in contact with the second binder layer with a flat surface, stress generated by expansion and shrinkage of the first active material particles is dispersed at the boundary of the first binder layer and the second binder layer. Therefore, internal stress caused by expansion and shrinkage generated in the first binder layer can be effectively absorbed at the boundary of the first binder layer and the second binder layer.

[0063] In addition, for example, at the boundary, the flat surface of the deformed particles can be in contact with the second active material particles.

[0064] Thus, at the boundary, the deformed particles of the first binder layer and the second active material particles of the second binder layer are in contact with each other in a surface and a point. Therefore, even if expansion and shrinkage of the first active material particles and the second active material particles occurs and the first active material particles and the second active material particles move due to charging and discharging or the like, the contact of the first active material particles and the second active material particles is easily maintained. Therefore, deterioration of electrode properties can be further suppressed.

[0065] In addition, for example, the deformed particles can include particles in which the length of the flat surface in a cross-sectional view of the electrode is greater than or equal to the average particle diameter of the non-deformed particles.

[0066] Thus, the deformed particles have a flat surface with sufficient width, and therefore, even if expansion and shrinkage of the first active material particles and the second active material particles occurs and the first active material particles and the second active material particles move due to charging and discharging or the like, the contact of the deformed particles contained in the first active material particles and the second active material particles is easily maintained.

[0067] Further, for example, the deformed particle can be a particle in which an angle formed by an outer periphery of the deformed particle and the flat surface of the deformed particle in a cross-sectional view of the electrode is 90° or more.

[0068] Thus, the deformed particle has a structure in which the width is equal to or more than the flat surface in a cross-sectional view, and thus the deformed particle is less likely to be deformed by stress to the flat surface. Therefore, even if expansion and contraction of the first active material particle and the second active material particle occur, the contact between the deformed particle and the second active material particle is easily maintained.

[0069] Further, for example, the deformed particle can be a particle in which an angle formed by an outer periphery of the deformed particle and the flat surface of the deformed particle in a cross-sectional view of the electrode is 90° or more.

[0070] Thus, the flat surface of the deformed particle has low roughness, and thus the contact between the deformed particle and the second active material particle can be easily ensured.

[0071] Further, for example, the deformed particle can be a particle in which an angle formed by an outer periphery of the deformed particle and the flat surface of the deformed particle in a cross-sectional view of the electrode is 90° or more.

[0072] Thus, the flat surface of the deformed particle has low roughness, and thus the contact between the deformed particle and the second active material particle can be easily ensured.

[0073] Further, for example, the deformed particle can be a particle in which an angle formed by an outer periphery of the deformed particle and the flat surface of the deformed particle in a cross-sectional view of the electrode is 90° or more.

[0074] Thus, the flat surface of the deformed particle has low roughness, and thus the contact between the deformed particle and the second active material particle can be easily ensured.

[0075] Further, for example, the deformed particle can be a particle in which an angle formed by an outer periphery of the deformed particle and the flat surface of the deformed particle in a cross-sectional view of the electrode is 90° or more.

[0076] Thus, the first particle can be uniformly attached to the surface of the first active material particle, and thus even if the first active material particle is pressed in the manufacturing of the electrode, the first active material particle is less likely to be subjected to excessive stress, and the breakage of the first active material particle can be suppressed.

[0077] Further, for example, it can be that in the cross-sectional view of the electrode, the first particles are attached to 80% or more of the surface of the first active material particles.

[0078] Thus, 80% or more of the surface of the first active material particles is covered with the first particles, so even if the first mixture layer is pressed during manufacture of the electrode, it is difficult to apply excess stress to the first active material particles, and it is possible to suppress breakage of the first active material particles 1.

[0079] Further, for example, it can be that the film thickness of the first mixture layer is in a range of 20 μm or more and 200 μm or less.

[0080] By making the film thickness of the first mixture layer 20 μm or more, it is possible to suppress breakage of the first active material particles in the thickness direction when the first mixture layer is pressed. Further, by making the film thickness of the first mixture layer 200 μm or less, it is possible to suppress escape of stress between the first active material particles in the plane direction and cause breakage of the current collector when the first mixture layer is pressed.

[0081] Further, for example, it can be that the first particles and the second particles are solid electrolytes.

[0082] Thus, by including a solid electrolyte in the active material mixture layer, ion conductivity in the active material mixture layer is improved, and electrode performance is improved.

[0083] Further, the battery of one embodiment of the present application includes a positive electrode, a negative electrode, and an electrolyte layer between the positive electrode and the negative electrode, and at least one of the positive electrode and the negative electrode is the electrode.

[0084] Thus, the battery of this embodiment can achieve a battery with excellent electrode performance because it includes the electrode.

[0085] Further, the method for manufacturing the electrode of one embodiment of the present application includes: forming a first mixture coating film over a current collector from a first mixture of first particles and first active material particles; deforming the surface of part of the first active material particles in the surface portion of the first mixture coating film to form a flat surface by pressing the first mixture coating film; and forming a second mixture coating film over the first mixture coating film after the pressing from a second mixture of second particles and second active material particles.

[0086] Thus, an electrode in which first active material particles including deformed particles having a flat surface facing the second solvent coating film at the boundary between the first solvent coating film and the second solvent coating film are formed can be produced. In such an electrode, stress generated by expansion and contraction of the first active material particles is dispersed at the boundary and is efficiently absorbed. Thus, by the production method of the present embodiment, an electrode having excellent electrode properties can be produced.

[0087] Further, by deforming the surface of a portion of the first active material particles in the surface portion of the first solvent coating film to form a flat surface, when the second solvent coating film is formed on the first solvent coating film after pressurization, the particles in the second solvent coating film easily flow on the flat surface of the first solvent coating film surface, and a uniform second solvent coating film can be formed.

[0088] Further, for example, the average particle diameter of the first particles can be 50% or less relative to the average particle diameter of the first active material particles.

[0089] Thus, the first particles can be uniformly attached to the surface of the first active material particles. Thus, the breakage of the first active material particles at the time of pressurization of the first solvent coating film can be suppressed.

[0090] Further, for example, the method of producing the electrode can further include mixing the first active material particles and the first particles in such a manner that 80% or more of the surface of the first active material particles is covered with the first particles, thereby preparing the first mixture.

[0091] Thus, 80% or more of the surface of the first active material particles is covered with the first particles, and thus the breakage of the first active material particles at the time of pressurization of the first solvent coating film can be suppressed.

[0092] Further, for example, the pressurization load of the first solvent coating film can be in a range of 100% or more and 300% or less of the compressive strength of one particle of the first active material particles.

[0093] By pressurizing the first solvent coating film with a load pressure in such a range, deformed particles can be favorably formed, and the breakage of the first active material particles can be suppressed. As a result, the breakage of the first active material particles can be suppressed, and deformed particles having a flat surface can be formed by deforming the first active material particles, and further, the non-deformed active material particles can also be less likely to break, and thus the decrease in electrode properties can be suppressed.

[0094] Hereinafter, an electrode, a battery, and a method for manufacturing an electrode according to an embodiment of the present application will be described with reference to the drawings. Note that each of the drawings is a schematic view and does not necessarily strictly illustrate the shape, the positional relationship, and the ratio. In each drawing, the same reference numeral is given to substantially the same component, and repetitive description is omitted or simplified at times.

[0095] In addition, each of the embodiments below shows one specific example of the present application, and the values, the shapes, the materials, the components, the arrangement positions of the components, and the connection methods are only examples and do not limit the present application. In addition, as to the components in the embodiments below, which are not described in the general technical solution showing the most general concept of the present application, the components are described as arbitrary components.

[0096] In addition, in this specification, terms indicating the relationship between elements such as parallel, and terms indicating the shape of elements such as rectangular, and a numerical range are not expressions indicating only the strict meaning, but expressions indicating that a substantially equivalent range, for example, a difference of several percent or less, is also included.

[0097] In addition, in this specification, a cross-sectional view is a view showing a cross section when a central portion of an electrode or a battery is cut in a stacking direction. In addition, in this specification, a "cross-sectional view" of an electrode means a case where a cross section when a central portion of an electrode or a battery is cut in a stacking direction is observed from the front.

[0098] In addition, in this specification, terms such as "upper" and "lower" in the configuration of a battery are not terms indicating the upward direction (vertically upward) and the downward direction (vertically downward) in the absolute spatial recognition, but are used as terms defined based on the relative positional relationship in the stacking order in the stacked configuration. Furthermore, the terms "upper" and "lower" are applicable not only to a case where two components are arranged in close contact with each other and the two components are in contact with each other, but also to a case where two components are arranged apart from each other with another component interposed therebetween.

[0099] (Embodiment)

[0100] (Electrode)

[0101] Use Figure 1 An electrode according to the present embodiment will be described. Figure 1 is a schematic cross-sectional view of the electrode 10 according to the present embodiment. Note that in Figure 1 , a region where the first particles 3 and the second particles 6 exist is indicated by a region with dots, and is a view in which illustration of the particle shape of the first particles 3 and the second particles 6 is omitted.

[0102] As Figure 1As shown, the electrode 10 of this embodiment includes a current collector 5 and an active substance mixture layer 11 located on the current collector 5 and comprising a first particle 3, a second particle 6, a first active substance particle 1, and a second active substance particle 4. The active substance mixture layer 11 has a first mixture layer 12 located on the current collector 5 and comprising the first particle 3 and the first active substance particle 1, and a second mixture layer 13 located on the first mixture layer 12 and comprising the second particle 6 and the second active substance particle 4. That is, in the active substance mixture layer 11, the first mixture layer 12 and the second mixture layer 13 are sequentially stacked on the current collector 5. Figure 1 As shown in the cross-sectional view of electrode 10, the active material mixture layer 11 has at least a portion of a boundary 11A where the first active material particles 1 and the second active material particles 4 are connected in a discontinuous state. The first active material particles 1 and the second active material particles 4 connected at the boundary 11A are not integrated and are not in a continuous state.

[0103] Because the electrode 10 of this embodiment has such a configuration, a contact portion exists at the boundary 11A between the first active material particle 1 in the first compound layer 12 and the second active material particle 4 in the second compound layer 13. Therefore, even if the first active material particle 1 and the second active material particle 4 move in the first compound layer 12 and the second compound layer 13 respectively due to expansion and contraction, since they exist in separate compound layers, the expansion and contraction are difficult to synchronize, and the contact point between the first active material particle 1 and the second active material particle 4 is easily maintained. Furthermore, the internal stress caused by the expansion and contraction of the first active material particle 1 and the second active material particle 4 can be absorbed at the boundary 11A, thus suppressing the breakage and buckling of the electrode 10. Therefore, the electrode 10 of this embodiment suppresses the deterioration of electrode performance even during charging and discharging and exposure to heat, thereby exhibiting excellent electrode performance and high durability.

[0104] The current collector 5 is a conductor that accepts and donates electrons to the active material compound layer 11. There are no particular limitations on the thickness and shape of the current collector 5; it can be appropriately determined according to the application. For example, the thickness of the current collector 5 can be in the range of 5 μm or more and 50 μm or less. By having a thickness of 5 μm or more, the current collector 5 is less prone to breakage; by having a thickness of 50 μm or less, the overall energy density of the battery using the electrode 10 can be improved.

[0105] The thickness of the first compound layer 12 is, for example, in the range of 20 μm or more and 200 μm or less. By having a thickness of 20 μm or more, the breakage of the first active material particles 1 in the thickness direction can be suppressed when the first compound layer 12 is pressurized. Furthermore, by having a thickness of 200 μm or less, stress escape in the planar direction between the first active material particles 1 and damage to the current collector 5 can be suppressed when the first compound layer 12 is pressurized. The thickness of the second compound layer 13 is not particularly limited and can be adjusted appropriately according to the application.

[0106] The proportions of the components contained in the active substance mixture layer 11 are not particularly limited. The proportions can be adjusted appropriately according to the intended use of the electrode 10.

[0107] The shapes of the first particle 3 and the second particle 6 can be, for example, spherical or ellipsoidal particle shapes. The average particle size (D) of the first particle 3... 50 For example, the average particle size (D) of the undeformed particle 1B described later, relative to the first active material particle 1. 50 The average particle size (D50) of the first particle 3 can be 50% or less, or even 2 μm or less. Therefore, the first particle 3 can be uniformly attached to the surface of the first active material particle 1. In the manufacturing method described later, excessive stress is less likely to be applied to the first active material particle 1 when the first compound layer 12 is pressurized, thus suppressing the breakage of the first active material particle 1. Furthermore, the filling rate within the active material compound layer 11 can be increased. The average particle size (D50) of the first particle 3 can be 0.01 μm or more, or even 0.1 μm or more. It should be noted that in this specification, the average particle size (D50) is... 50 For example, the average particle size can be measured using a particle size analyzer, or it can be measured using laser analysis and scattering particle size distribution measuring devices based on volume. Additionally, the average particle size (D...) 50 The average particle size can be measured based on the cross-sectional SEM (Scanning Electron Microscope) image of electrode 10.

[0108] The average particle size of the second particle 6 (D) 50 For example, relative to the average particle size (D) of the second active material particle 4 50 The particle size (D) is 50% or less, and can be 2 μm or less. Therefore, the second particle 6 can uniformly adhere to the surface of the second active material particle 4. In the manufacturing method described later, excessive stress is not easily applied to the second active material particle 4 when the second compound layer 13 is pressurized, thus suppressing the breakage of the second active material particle 4. Furthermore, the filling rate within the active material compound layer 11 can be increased. The average particle size (D) of the second particle 6... 50) can be 0.01 pm or more, or 0.1 pm or more. The average particle diameter (D 50 ) of the first particles 3 can be the same as or different from the average particle diameter (D 50 ) of the second particles 6.

[0109] The first particles 3 and the second particles 6 are, for example, solid electrolytes. Thereby, ion conductivity within the active material mixture layer 11 can be improved. The materials of the first particles 3 and the second particles 6 are not particularly limited, and can be selected according to the use of the electrode 10. The first particles 3 and the second particles 6 can use the same material, for example. The first particles 3 and the second particles 6 can also use different materials.

[0110] Further, for example, in a cross-sectional view of the electrode 10, the first particles 3 are attached to 80% or more of the surface of the first active material particles 1. Thereby, 80% or more of the surface of the first active material particles 1 is coated with the first particles 3, and thus, in the manufacturing method described later, the breakage of the first active material particles 1 at the time of pressing of the first mixture layer 12 can be suppressed.

[0111] The materials of the first active material particles 1 and the second active material particles 4 are not particularly limited, and can be selected according to the use of the electrode 10. In the electrode 10 of the present embodiment, both a positive electrode and a negative electrode can be applied, and, for example, in the case of being used as a positive electrode, as the materials of the current collector 5 and the active material mixture layer 11, materials that function as a positive electrode can be adopted. Further, in the electrode 10, for example, in the case of being used as a negative electrode, as the materials of the current collector 5 and the active material mixture layer 11, materials that function as a negative electrode can be adopted. In the case of the electrode 10 being a positive electrode, for example, the current collector 5 is a positive electrode current collector, and the active material mixture layer 11 is a positive electrode active material mixture layer that contains positive electrode active material particles as the first active material particles 1 and the second active material particles 4. Further, in the case of the electrode 10 being a negative electrode, for example, the current collector 5 is a negative electrode current collector, and the active material mixture layer 11 is a negative electrode active material mixture layer that contains negative electrode active material particles as the first active material particles 1 and the second active material particles 4.

[0112] The first active material particles 1 and the second active material particles 4 are, for example, particles. The average particle diameter (D 50 ) of the first active material particles 1 and the second active material particles 4 is, for example, in a range of 50 nm or more and 50 pm or less, or in a range of 1 pm or more and 15 pm or less. By the average particle diameter (D 50 ) of the first active material particles 1 and the second active material particles 4 being 50 nm or more, handleability is improved. Further, by the average particle diameter (D 50The particle size is below 50 μm, allowing for easy and flat formation of the electrode 10. The average particle size (D) of the first active material particles 1 50 The average particle size (D) of the second active substance particles 4 50 They can be the same or different.

[0113] The content of the first active substance particle 1 in the first compound layer 12 and the content of the second active substance particle 4 in the second compound layer 13 are not particularly limited. For example, they can be in the range of 40% by weight or more and 99% by weight or less, or 70% by weight or more and 95% by weight or less. The content of the first active substance particle 1 in the first compound layer 12 and the content of the second active substance particle 4 in the second compound layer 13 can be the same or different.

[0114] The compressive strength of a single particle of the first active material particle 1 is, for example, 100 MPa or more. Therefore, in the manufacturing method described later, the breakage of the first active material particle 1 under pressure can be suppressed. In this specification, the compressive strength of a single particle refers to the stress at which a single particle is broken when compressed.

[0115] In addition, such as Figure 1 As shown, the first active material particle 1 includes, for example, a deformed particle 1A having a flat surface 1C facing the second compound layer 13 at boundary 11A, and a non-deformed particle 1B without the flat surface 1C. Furthermore, for example, at boundary 11A, the flat surface 1C of the deformed particle 1A is in contact with the second active material particle 4. Thus, at boundary 11A, the deformed particle 1A of the first compound layer 12 and the second active material particle 4 of the second compound layer 13 are... Figure 1 As shown, the surfaces and points are connected. Therefore, even if the first active material particles 1 and 4 expand and contract due to charging and discharging, or if the first active material particles 1 and 4 experience slight movement, the contact points between the first active material particles 1 and 4 can be easily maintained. Furthermore, since a portion of the first compound layer 12 is in contact with the second compound layer 13 on the flat surface 1C, the stress generated by the expansion and contraction of the first active material particles 1 is dispersed at the boundary 11A between the first compound layer 12 and the second compound layer 13. Therefore, the internal stress caused by the expansion and contraction generated within the first compound layer 12 can be effectively absorbed at the boundary 11A.

[0116] Deformed particle 1A, for example, is contained in a flat surface 1C in a cross-sectional view of electrode 10. The length of this surface is equal to the average particle size (D) of the undeformed particle 1B. 50) the above particles. Thus, the deformed particle 1A has a flat surface 1C of a sufficient width, and therefore even if the first active material particle 1 and the second active material particle 4 are minutely moved due to expansion and shrinkage of the first active material particle 1 and the second active material particle 4 caused by charge and discharge and the like, the junction of the deformed particle 1A included in the first active material particle 1 and the second active material particle 4 is easily maintained.

[0117] Further, the deformed particle 1A, for example, includes a particle in which an angle formed by an outer periphery of the deformed particle 1A and the flat surface 1C of the deformed particle 1A in a cross-sectional view of the electrode 10 is 90° or more. Thus, the deformed particle 1A includes a structure in which a width is equal to or more than a length of the flat surface in a cross-sectional view as the distance from the flat surface 1C increases, and therefore the deformed particle 1A is less likely to be deformed due to stress to the flat surface 1C. Therefore, even if expansion and shrinkage of the first active material particle 1 and the second active material particle 4 occur, the junction of the deformed particle 1A and the second active material particle 4 is easily maintained.

[0118] Further, the deformed particle 1A, for example, includes a particle having an R shape that is a particle in which a surface in contact with the boundary 11A in a cross-sectional view of the electrode 10 is 10 times or more than an average particle diameter (D 50 ) of the non-deformed particle 1B. Thus, even if the first active material particle 1 and the second active material particle 4 are minutely moved by charge and discharge, the junction of the deformed particle 1A and the second active material particle 4 is easily maintained.

[0119] Further, for example, in a cross-sectional view of the electrode 10, a proportion of a total of lengths of the flat surface 1C at the boundary 11A with respect to a length of the boundary 11A is 80% or more. Thus, the flat surface 1C of the deformed particle 1A exists in 80% or more of the length of the boundary 11A in the cross-sectional view. Therefore, even if expansion and shrinkage of the first active material particle 1 and the second active material particle 4 occur, the junction of the deformed particle 1A and the second active material particle 4 is easily maintained.

[0120] Further, in a cross-sectional view of the electrode 10, an average particle distance between the deformed particles 1A at the boundary 11A, for example, is 130% or less than an average particle diameter (D 50 ) of the non-deformed particle 1B. Thus, the interval between the deformed particles 1A is narrowed, and therefore the junction of the deformed particle 1A and the second active material particle 4 can be more easily ensured. Therefore, even if expansion and shrinkage of the first active material particle 1 and the second active material particle 4 occur, the junction of the deformed particle 1A and the second active material particle 4 is easily maintained.

[0121] In addition, in the cross-sectional view of the electrode 10, the Rz (maximum height) of the flat surface 1C of the deformed particle 1A is, for example, 10 (μm) or less. Due to this, the roughness of the flat surface 1C of the deformed particle 1A is low, and thus sufficient contact of the deformed particle 1A with the second active material particle 4 can be easily ensured.

[0122] In addition, the Rz of the boundary 11A in the active material mixture layer 11 is, for example, 10 or less. Due to this, internal stress caused by expansion and contraction of the first active material particle 1 and the second active material particle 4 can be absorbed at the boundary 11A.

[0123] Note that in the present specification, the active material mixture layer is not limited to two layers only according to the terms "first" and "second" of the active material particles coated on the electrode, the mixture layer, and the mixture layer coating film prepared in the manufacturing method described later, but can be a stack of three or more layers. For example, the active material mixture layer 11 can have two or more first mixture layers 12 and one second mixture layer 13, or one first mixture layer 12 and two or more second mixture layers 13. In addition, the active material mixture layer 11 can have two or more first mixture layers 12 and two or more second mixture layers 13. In this way, in the case where the active material mixture layer 11 is three or more layers, the order of the stack of the layers is not particularly limited, and for example, the second mixture layer 13 can be disposed as the layer farthest from the current collector 5.

[0124] Next, an example of a case where the electrode 10 is used as a positive electrode of a full solid-state battery will be described.

[0125] Figure 2 is a schematic cross-sectional view of the positive electrode 50 of the present embodiment. Note that in Figure 2 , the area with dots indicates the area where the solid electrolyte 25 and the solid electrolyte 28 exist, and is a view in which the particle shape of the solid electrolyte 25 and the solid electrolyte 28 is omitted. This is the same for the following Figure 3 , Figure 4 and Figure 5 .

[0126] As Figure 2As shown, the positive electrode 50 of the present embodiment includes the positive electrode current collector 27 and the positive electrode active material composite layer 20. The positive electrode active material composite layer 20 includes the first positive electrode composite layer 21 and the second positive electrode composite layer 22. The first positive electrode composite layer 21 is disposed on the positive electrode current collector 27 and includes the solid electrolyte 25 and the first positive electrode active material particle 23. The second positive electrode composite layer 22 is disposed on the first positive electrode composite layer 21 and includes the solid electrolyte 28 and the second positive electrode active material particle 26. In a cross-sectional view of the positive electrode 50, the positive electrode active material composite layer 20 has a boundary 20A at which the first positive electrode active material particle 23 and the second positive electrode active material particle 26 are discontinuously connected at least in part. The positive electrode 50 is, for example, a positive electrode for a full solid battery.

[0127] The positive electrode 50 of the present embodiment includes the positive electrode current collector 27 as an example of the current collector 5. The positive electrode current collector 27 can be, for example, a metal foil. The positive electrode current collector 27 can be, for example, a foil-shaped body, a plate-shaped body, or a mesh-shaped body formed of aluminum, gold, platinum, zinc, copper, SUS, nickel, tin, titanium, or an alloy of two or more of these, or the like.

[0128] The thickness and shape of the positive electrode current collector 27 are not particularly limited and can be appropriately set according to the application. The thickness of the positive electrode current collector 27 can be the same as the thickness of the current collector 5 described above.

[0129] In the present embodiment, the positive electrode 50 includes the positive electrode active material composite layer 20 disposed on the positive electrode current collector 27 as an example of the active material composite layer 11. The positive electrode active material composite layer 20 includes the first positive electrode composite layer 21 as an example of the first composite layer 12 and the second positive electrode composite layer 22 as an example of the second composite layer 13. The positive electrode active material composite layer 20 is a laminate in which the first positive electrode composite layer 21 and the second positive electrode composite layer 22 are stacked on the positive electrode current collector 27. The first positive electrode composite layer 21 includes the solid electrolyte 25 as an example of the first particle 3 and the first positive electrode active material particle 23 as an example of the first active material particle 1. The second positive electrode composite layer 22 includes the solid electrolyte 28 as an example of the second particle 6 and the second positive electrode active material particle 26 as an example of the second active material particle 4.

[0130] The film thickness of the first positive electrode composite layer 21 is, for example, in the range of 20 μm or more and 200 μm or less, like the first composite layer 12 described above. The film thickness of the second positive electrode composite layer 22 is not particularly limited and can be appropriately adjusted according to the application.

[0131] The blending ratio of the components included in the positive electrode active material composite layer 20 is not particularly limited. The blending ratio can be appropriately adjusted according to the application of the positive electrode 50.

[0132] The solid electrolyte 25 and the solid electrolyte 28 are appropriately selected depending on the kind of ion to be conducted (e.g., lithium ion), and at least one of a sulfide-based solid electrolyte and an oxide-based solid electrolyte can be used, for example.

[0133] As the sulfide-based solid electrolyte, for example, Li2S-SiS2, LiI-Li2S-SiS2, LiI-Li2S-P2S5, LiI-Li2S-P2O5, LiI-Li3PO4-P2S5, and Li2S-P2S5, and the like can be given. In the case where a sulfide-based solid electrolyte is used as the solid electrolyte 25, since lithium ion conductivity is excellent, a sulfide-based solid electrolyte containing Li (lithium), P (phosphorus), and S (sulfur) can be used. As the sulfide-based solid electrolyte, one kind of sulfide-based solid electrolyte can be used alone, or two or more kinds of sulfide-based solid electrolytes can be used in combination. In addition, the sulfide-based solid electrolyte can be crystalline, or can be amorphous, or can be glass-ceramic. Note that the above description of "Li2S-P2S5" means a sulfide-based solid electrolyte containing Li2S and P2S5, and the same applies to other descriptions.

[0134] The sulfide-based solid electrolyte is, for example, a sulfide glass-ceramic containing Li2S and P2S5, and in the case where the ratio of Li2S and P2S5 is Li2S / P2S5 = molar ratio, the molar ratio is preferably in the range of 2.3 or more and 4 or less, and more preferably in the range of 3 or more and 4 or less. By making the molar ratio in this range, a crystal structure with high ion conductivity can be obtained while maintaining the lithium concentration that affects the characteristics of the battery. In addition, the amount of P2S5 for reaction and bonding with the binder described later can be sufficiently ensured.

[0135] As the oxide-based solid electrolyte, for example, LiPON, Li3PO4, Li2SiO2, Li2SiO4, Li 0.5 La 0.5 TiO3, Li 1.3 Al 0.3 Ti 0.7 (PO4)3, La 0.51 Li 0.34 TiO 0.74 and Li 1.5 Al 0.5 Ge 1.5 (PO4)3, and the like can be given. As the oxide-based solid electrolyte, one kind of oxide-based solid electrolyte can be used alone, or two or more kinds of oxide-based solid electrolytes can be used in combination.

[0136] The shape and the average particle diameter (D 50For example, as long as the shape and average particle size (D) of the first particle 3 and the second particle 6 described above are consistent, 50 That's all.

[0137] In addition, similar to the first active material particle 1 described above, for example in a cross-sectional view of the positive electrode 50, more than 80% of the surface of the first positive electrode active material particle 23 is covered with a solid electrolyte 25.

[0138] The first positive electrode active material particle 23 and the second positive electrode active material particle 26 can be any material that inserts or extracts lithium (Li) into the crystal structure at a potential higher than that of the negative electrode and then undergoes oxidation or reduction. There are no particular limitations on the types of the first positive electrode active material particle 23 and the second positive electrode active material particle 26; they can be appropriately selected according to the application of the positive electrode 50. Examples of first positive electrode active material particles 23 and 26 include oxide active materials and sulfide active materials. It should be noted that the first positive electrode active material particle 23 and the second positive electrode active material particle 26 can be the same material or different materials.

[0139] In this embodiment, the first positive electrode active material particle 23 and the second positive electrode active material particle 26 can be, for example, oxide active materials (containing lithium transition metal oxides). Examples of oxide active materials include LiC. o O2, LiNiO2, LiMn2O4, LiC o PO4, LiNiPO4, LiFePO4, LiMnPO4, and compounds obtained by substituting the transition metal of these compounds with one or more different elements. Examples of compounds obtained by substituting the transition metal of the aforementioned compounds with one or more different elements include LiNiPO4. 1 / 3 C o1 / 3 Mn 1 / 3 O2, LiNi 0.8 Co 0.15 Al 0.05 O2 and LiNi 0.5 Mn 1.5 O2, etc.

[0140] In addition, the content of the first positive electrode active material particle 23 in the first positive electrode mixture layer 21 and the content of the second positive electrode active material particle 26 in the second positive electrode mixture layer 22 can be the same as the content of the first active material particle 1 in the first mixture layer 12 and the content of the second active material particle 4 in the second mixture layer 13 as described above.

[0141] The surface of the first positive electrode active material particle 23 and the second positive electrode active material particle 26 can be coated with a coating layer. Thereby, the reaction of the first positive electrode active material particle 23 and the second positive electrode active material particle 26 (for example, an oxide active material) with the solid electrolyte 25 (for example, a sulfide-based solid electrolyte) can be suppressed. As a material of the coating layer, for example, a lithium ion-conductive oxide such as LiNbO3, Li3PO4, LiPON, or the like can be cited. The average thickness of the coating layer is, for example, in a range of 1 nm or more and 20 nm or less, or can be in a range of 1 nm or more and 10 nm or less.

[0142] The ratio of the first positive electrode active material particle 23 to the solid electrolyte 25 and the ratio of the second positive electrode active material particle 26 to the solid electrolyte 28 contained in the positive electrode active material mixture layer 20 are each in a range of, for example, 0.67 or more and 99 or less, or can be in a range of 2.3 or more and 19 or less, in terms of the weight ratio of the positive electrode active material / solid electrolyte. By making the weight ratio in this range, both the lithium ion conduction path and the electron conduction path within the positive electrode active material mixture layer 20 can be ensured. The above weight ratio can be the same or different in the first positive electrode mixture layer 21 and the second positive electrode mixture layer 22.

[0143] The positive electrode active material mixture layer 20 of the present embodiment can contain a binder. Thereby, the adhesion strength of the materials to each other within the positive electrode active material mixture layer 20 can be improved.

[0144] As the binder, for example, synthetic rubbers such as butadiene rubber, isoprene rubber, styrene-butadiene rubber (SBR), styrene-butadiene-styrene (SBS), styrene-ethylene-butadiene-styrene (SEBS), ethylene-propylene rubber, butyl rubber, chloroprene rubber, acrylonitrile-butadiene rubber, acrylic rubber, silicone rubber, fluororubber, and polyurethane rubber, polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP), polyimide, polyamide, polyamide-imide, polyvinyl alcohol, and chlorinated polyethylene (CM), or the like can be cited.

[0145] The positive electrode active material mixture layer 20 can contain an electrically conductive aid. Thereby, the electron conductivity within the positive electrode active material mixture layer 20 can be increased, and thus the electron conduction path in the positive electrode active material mixture layer 20 can be ensured, and the internal resistance of the all-solid battery using the positive electrode 50 can be reduced. Therefore, the amount of current that can be conducted through the electron conduction path increases, and thus the charge and discharge characteristics of the all-solid battery are improved.

[0146] The conductive aid is not particularly limited as long as it improves the electron conductivity of the positive electrode active material mixture layer 20. As the conductive aid, for example, acetylene black, Ketjen black (registered trademark), carbon black, graphite, carbon fiber, and the like can be used. The conductive aid can be used alone using one conductive aid or can be used in combination using two or more conductive aids.

[0147] The shape and average particle diameter (D 50 ) of the first positive electrode active material particle 23 and the second positive electrode active material particle 26 are, for example, the same as the shape and average particle diameter (D 50 ) of the first active material particle 1 and the second active material particle 4 described above.

[0148] The particle compression strength of one particle of the first positive electrode active material particle 23 is, for example, 100 MPa or more, like the first active material particle 1 described above. Thereby, in the manufacturing method described later, the breakage of the first positive electrode active material particle 23 at the time of pressurization can be suppressed.

[0149] In the positive electrode 50 of the present embodiment, the first positive electrode active material particle 23 includes, for example, a deformed positive electrode active material particle 23A having a flat surface 23C facing the second positive electrode mixture layer 22 at the boundary 20A and a non-deformed positive electrode active material particle 23B not having the flat surface 23C. The deformed positive electrode active material particle 23A is an example of the deformed particle 1A, and the non-deformed positive electrode active material particle 23B is an example of the non-deformed particle 1B.

[0150] Figure 3 is an enlarged cross-sectional view of the vicinity of the boundary 20A of the first positive electrode mixture layer 21 and the second positive electrode mixture layer 22. As shown in Figure 3 , in the positive electrode 50 of the present embodiment, at the boundary 20A of the cross section of the positive electrode active material mixture layer 20, the deformed positive electrode active material particle 23A in the first positive electrode mixture layer 21 is in contact with the second positive electrode active material particle 26 with the flat surface 23C of the particle.

[0151] Like the deformed particle 1A described above, the deformed positive electrode active material particle 23A includes, for example, a particle in which the length L of the flat surface 23C in the cross-sectional view of the positive electrode 50 is the average particle diameter D or more of the non-deformed positive electrode active material particle 23B. In other words, in at least a part of the particles of the deformed positive electrode active material particle 23A, the length L of the flat surface 23C in the cross-sectional view of the positive electrode 50 is the average particle diameter D (D 50 ) or more of the non-deformed positive electrode active material particle 23B.

[0152] Further, as with the deformed particle 1A described above, the deformed positive electrode active material particle 23A includes a particle in which an angle A formed by an outer periphery of the deformed positive electrode active material particle 23A and a flat surface 23C of the deformed positive electrode active material particle 23A is 90° or greater in a cross-sectional view of the positive electrode 50. In other words, at least some of the deformed positive electrode active material particles 23A in the first positive electrode mixture layer 21 have an angle A formed by an outer periphery of the deformed positive electrode active material particle 23A and a flat surface 23C of the deformed positive electrode active material particle 23A that is 90° or greater.

[0153] Further, as with the deformed particle 1A described above, the deformed positive electrode active material particle 23A includes, for example, a particle having an R shape in which a surface in contact with the boundary 20A is 10 times or greater than the average particle diameter D(D 50 ) of the non-deformed positive electrode active material particle 23B in a cross-sectional view of the positive electrode 50. In other words, at least some of the deformed positive electrode active material particles 23A have an R shape in which a surface in contact with the boundary 20A is 10 times or greater than the average particle diameter D(D 50 ) of the non-deformed positive electrode active material particle 23B.

[0154] Further, for example, as with the boundary 11A described above, a ratio of a total length of the flat surface 23C at the boundary 20A to the length B of the boundary 20A is 80% or greater.

[0155] Further, as with the deformed particle 1A described above, an average inter-particle distance d between the deformed positive electrode active material particles 23A at the boundary 20A is, for example, 130% or less than the average particle diameter D(D 50 ) of the non-deformed positive electrode active material particle 23B in a cross-sectional view of the positive electrode 50. The average inter-particle distance d between the deformed positive electrode active material particles 23A is an average value of distances between centers of the flat surfaces 23C of adjacent deformed positive electrode active material particles 23A.

[0156] Further, as with the deformed particle 1A described above, an Rz of the flat surface 23C of the deformed positive electrode active material particle 23A is, for example, 10 or less in a cross-sectional view of the positive electrode 50.

[0157] Further, as with the active material mixture layer 11 described above, an Rz of the boundary 20A in the positive electrode active material mixture layer 20 is, for example, 10 or less.

[0158] By providing such a positive electrode 50, the same advantageous effects as the electrode 10 described above can be obtained.

[0159] <Battery>

[0160] Next, the battery of the present embodiment will be described. The electrode 10 of the present embodiment is used, for example, as at least one of the positive electrode and the negative electrode of a battery in which a positive electrode, an electrolyte layer, and a negative electrode are sequentially stacked. In the battery of the present embodiment, the electrode 10 can be used as the positive electrode, the electrode 10 can be used as the negative electrode, and the electrode 10 can be used in both the positive electrode and the negative electrode.

[0161] In the present embodiment, reference will be made to Figure 4 A full-solid battery 100, which is an example of a battery using the positive electrode 50 and the negative electrode 60 as the electrode 10, will be described. Figure 4 is a schematic cross-sectional view of the full-solid battery 100. Note that, in Figure 4 , the area with a dot indicates an area in which the solid electrolyte 34, the solid electrolyte 37, and the solid electrolyte 41 exist, and is a view in which the particle shapes of the solid electrolyte 34, the solid electrolyte 37, and the solid electrolyte 41 are omitted.

[0162] Note that the battery of the present embodiment is not limited to the full-solid battery 100, and can be a battery of another configuration as long as the battery uses the electrode 10.

[0163] As shown in Figure 4 , the full-solid battery 100 includes the positive electrode 50, the negative electrode 60, and the solid electrolyte layer 40 between the positive electrode 50 and the negative electrode 60. In the full-solid battery 100, the positive electrode 50, the solid electrolyte layer 40, and the negative electrode 60 are sequentially stacked. In the full-solid battery 100, the positive electrode 50 and the negative electrode 60 can be used as an example of the electrode 10. In addition, the solid electrolyte layer 40 is an example of the electrolyte layer. Note that a unit structure of the positive electrode 50, the solid electrolyte layer 40, and the negative electrode 60 is shown in Figure 4 , but the battery of the present embodiment can be a full-solid battery in which a plurality of unit structures are stacked. In addition, in the full-solid battery 100 of the present embodiment, the electrode 10 of the present embodiment is used as the positive electrode 50 and the negative electrode 60, and the electrode 10 is used in at least one of the positive electrode 50 and the negative electrode 60.

[0164] Regarding the positive electrode 50 in the full-solid battery 100 of the present embodiment, the description will be omitted because it is the same as described above.

[0165] The negative electrode 60 in the all-solid battery 100 of this embodiment includes, for example, a negative electrode current collector 36 made of a metal foil or the like, and a negative electrode active material mixture layer 30 having a first negative electrode mixture layer 31 and a second negative electrode mixture layer 32. The first negative electrode mixture layer 31 is provided on the negative electrode current collector 36 and contains a solid electrolyte 34 and first negative electrode active material particles 33. The second negative electrode mixture layer 32 is provided on the first negative electrode mixture layer 31 and contains a solid electrolyte 37 and second negative electrode active material particles 35. In a cross-sectional view of the negative electrode 60, the negative electrode active material mixture layer 30 has a boundary 30A at which the first negative electrode active material particles 33 and the second negative electrode active material particles 35 are in contact in a discontinuous state at least in part. The negative electrode current collector 36 is an example of the current collector 5, and the negative electrode active material mixture layer 30 is an example of the active material mixture layer 11. The first negative electrode mixture layer 31 containing the solid electrolyte 34 and the first negative electrode active material particles 33 is an example of the first mixture layer 12 containing the first particles 3 and the first active material particles 1, and the second negative electrode mixture layer 32 containing the solid electrolyte 37 and the second negative electrode active material particles 35 is an example of the second mixture layer 13 containing the second particles 6 and the second active material particles 4. Note that in the following description of the negative electrode 60, matters common to the electrode 10 and the positive electrode 50 are omitted or simplified.

[0166] The same material as that described in the positive electrode current collector 27 can be used as the negative electrode current collector 36. The same material as that of the positive electrode current collector 27 can be used as the negative electrode current collector 36, or a different material can be used.

[0167] The first negative electrode active material particles 33 and the second negative electrode active material particles 35 are materials that insert or extract lithium within a crystal structure and undergo oxidation or reduction in association therewith at a lower potential than the first positive electrode active material particles 23 and the second positive electrode active material particles 26.

[0168] As the first negative electrode active material particles 33 and the second negative electrode active material particles 35, for example, there can be mentioned metals such as lithium, indium, tin, and silicon, which easily undergo alloying with lithium, carbon materials such as hard carbon and graphite, and oxide active materials such as Li4Ti5O12, Li7Ti2O6, and SiO. 12 and SiO x As the first negative electrode active material particles 33 and the second negative electrode active material particles 35, one kind of negative electrode active material can be used alone, or two or more kinds of active material particles can be used in combination. In addition, the same material can be used as the first negative electrode active material particles 33 and the second negative electrode active material particles 35, or different materials can be used.

[0169] The ratio of the first negative electrode active material particles 33 to the solid electrolyte 34 and the ratio of the second negative electrode active material particles 35 to the solid electrolyte 37 included in the negative electrode active material mixture layer 30 may, for example, be in a range of 0.66 or more and 19 or less or in a range of 1 or more and 5.67 or less in terms of weight ratio of negative electrode active material / solid electrolyte. By the weight ratio being in this range, both the lithium ion conduction path and the electron conduction path within the negative electrode active material mixture layer 30 can be ensured. The above weight ratio may, for example, be different between the first negative electrode mixture layer 31 and the second negative electrode mixture layer 32.

[0170] For example, as shown in FIG. 3, the first negative electrode active material particles 33 include deformed negative electrode active material particles 33A and non-deformed negative electrode active material particles 33B. The deformed negative electrode active material particles 33A have flat surfaces 33C facing the second negative electrode mixture layer 32 at boundaries 30A. The non-deformed negative electrode active material particles 33B do not have flat surfaces 33C. Figure 4

[0171] As the solid electrolyte 25, the solid electrolyte 28, the solid electrolyte 34, and the solid electrolyte 37, the same substance can be used or different substances can be used for at least one of the solid electrolyte 25, the solid electrolyte 28, the solid electrolyte 34, and the solid electrolyte 37.

[0172] A binder can be included in the negative electrode active material mixture layer 30. As the kind of the binder, the same binder as that which can be included in the positive electrode active material mixture layer 20 described above can be used.

[0173] An electrically conductive aid can be included in the negative electrode active material mixture layer 30. As the kind of the electrically conductive aid, the same electrically conductive aid as that which can be included in the positive electrode active material mixture layer 20 described above can be used. Thereby, the electron conductivity within the negative electrode active material mixture layer 30 can be increased, and thus the electron conduction path in the negative electrode active material mixture layer 30 can be ensured, and the internal resistance of the all-solid battery 100 can be reduced. Thus, the amount of current that can be conducted through the electron conduction path increases, and thus the charge and discharge characteristics of the all-solid battery 100 are improved.

[0174] ​The solid electrolyte layer 40 contains a solid electrolyte 41 having metal ion conductivity of lithium ions or the like. As for the solid electrolyte 41, the same solid electrolyte as that described in the solid electrolyte 25 and the solid electrolyte 28 described above can be used. As the solid electrolyte 41, the same solid electrolyte as the solid electrolyte 25, the solid electrolyte 28, the solid electrolyte 34, or the solid electrolyte 37 can be used, or a solid electrolyte different from the solid electrolyte 25, the solid electrolyte 28, the solid electrolyte 34, and the solid electrolyte 37 can be used.

[0175] In order to improve the adhesion strength of the solid electrolyte 41 to each other, the solid electrolyte layer 40 can contain a binder. The binder can use the same binder as that which can be contained in the positive electrode active material composite layer 20 described above. In the case where the solid electrolyte layer 40 contains a binder, for example, the content of the binder in the solid electrolyte layer 40 is 1% by mass or less of the solid electrolyte 41. The solid electrolyte layer 40 can not contain a binder. By making the content of the binder in the solid electrolyte layer 40 be 1% by mass or less of the solid electrolyte 41, the lithium ion conduction of the solid electrolyte layer 40 is not easily hindered, and the charge-discharge characteristics of the all-solid battery 100 are not easily deteriorated. Note that not containing a binder means substantially not containing a binder, and the content of the binder in the solid electrolyte layer 40 is 100 ppm or less of the solid electrolyte 41. In the case where the solid electrolyte layer 40 does not contain a binder, the solid electrolyte 41 is used as a binder. The solid electrolyte 41 is bonded to each other by sintering of the solid electrolyte 41.

[0176] In the all-solid battery 100 of the present embodiment, although not shown, for example, a terminal (a metal positive electrode lead) is attached to the surface of the positive electrode current collector 27 on the side opposite to the positive electrode active material composite layer 20 by welding or the like, and a terminal (a metal negative electrode lead) is attached to the surface of the negative electrode current collector 36 on the side opposite to the negative electrode active material composite layer 30 by welding or the like. The all-solid battery 100 thus obtained, or a battery pack in which a plurality of all-solid batteries 100 are connected, can be housed in a battery case, and the positive electrode lead and the negative electrode lead can be led to the outside of the battery case, and the battery case can be sealed.

[0177] As the battery case, for example, a bag formed of an aluminum laminate film or the like, or an arbitrary shape case of metal (for example, SUS, iron, aluminum, or the like) or resin can be used.

[0178] <Manufacturing Method>

[0179] Next, the manufacturing method of the electrode of the present embodiment will be described.

[0180] The manufacturing method of the electrode 10 of the present embodiment includes: forming a first mixture layer on the current collector 5 from a first mixture of the first particles 3 and the first active material particles 1; deforming the surface of a part of the first active material particles 1 in the surface portion of the first mixture layer by pressing the first mixture layer, to form a flat surface 1C; and forming a second mixture layer on the pressed first mixture layer from a second mixture of the second particles 6 and the second active material particles 4. The first mixture layer 12 is formed by pressing the formed first mixture layer, and the second mixture layer 13 is formed by forming the second mixture layer on the pressed first mixture layer. Thus, the electrode 10 in which the active material mixture layer 11 is stacked on the current collector 5 can be obtained. By such a manufacturing method, the electrode 10 provided with the first mixture layer 12 containing the first active material particles 1 including the deformed particles 1A having the flat surface 1C facing the second mixture layer 13 at the boundary 11A can be manufactured.

[0181] Further, the manufacturing method of the electrode 10 includes, for example: mixing the first active material particles 1 and the first particles 3 so that the first particles 3 adhere to 80% or more of the surfaces of the first active material particles 1, to thereby prepare the first mixture. Further, for example, the average particle diameter (D 50 ) of the first particles 3 is 50% or less of the average particle diameter (D 50 ) of the first active material particles 1. Further, the pressing load of the first mixture layer is, for example, in the range of 100% or more and 300% or less of the 1-particle compression strength of the first active material particles 1.

[0182] Hereinafter, the manufacturing method of the electrode 10 will be described with reference to Figure 5 the case where the electrode 10 is a positive electrode 50 for a full solid-state battery. Figure 5 is a view for explaining the manufacturing method of the positive electrode 50 of the present embodiment. Figure 5 schematically cross-sectional views of each manufacturing stage of the positive electrode 50. As Figure 5 indicated, the manufacturing method of the positive electrode 50 includes, for example, a first mixture layer coating process and a second mixture layer coating process.

[0183] The first mixture layer coating process includes a process of forming a first positive electrode mixture coating film on the positive electrode current collector 27 from a first mixture of the solid electrolyte 25 and the first positive electrode active material particles 23, and a process of deforming the surface of a portion of the first positive electrode active material particles 23 in the surface portion of the first positive electrode mixture coating film by applying pressure to the first positive electrode mixture coating film, thereby forming a flat surface 23C. In other words, the first mixture layer coating process includes a process of forming a first positive electrode mixture coating film containing the solid electrolyte 25 and the first positive electrode active material particles 23 on the positive electrode current collector 27, and a process of deforming the first positive electrode active material particles 23 to form deformed positive electrode active material particles 23A having a flat surface 23C by applying pressure to the first positive electrode mixture coating film.

[0184] The second mixture layer coating process includes a process of forming a second positive electrode mixture coating film from a second mixture of the solid electrolyte 28 and the second positive electrode active material particles 26 on the first positive electrode mixture coating film after pressure application. In other words, the second mixture layer coating process includes a process of forming a second positive electrode mixture coating film containing the solid electrolyte 28 and the second positive electrode active material particles 26 on the first positive electrode mixture coating film after pressure application.

[0185] The first positive electrode mixture coating film is an example of the first mixture coating film, and the second positive electrode mixture coating film is an example of the second mixture coating film. Details of each process will be described below.

[0186] First, in the first mixture layer coating process, a positive electrode mixture is prepared as a first mixture by mixing the desired solid electrolyte 25, the first positive electrode active material particles 23, and other components such as a binder, a conductive aid, and the like, as needed. The specific form of each component incorporated in the positive electrode mixture is as described above for the positive electrode 50.

[0187] In the present embodiment, for example, the first positive electrode active material particles 23 and the solid electrolyte 25 are mixed while applying a moderate shear force and pressure in a manner in which the solid electrolyte 25 adheres to 80% or more of the surface of the first positive electrode active material particles 23, thereby preparing a uniformly dispersed positive electrode mixture. The method of mixing the first positive electrode active material particles 23 and the solid electrolyte 25 is not particularly limited, and a general method can be used.

[0188] In the present embodiment, for example, the average particle diameter of the solid electrolyte 25 is 50% or less relative to the average particle diameter of the first positive electrode active material particles 23. Thus, the solid electrolyte 25 can be uniformly adhered to the surface of the first positive electrode active material particles 23.

[0189] Next, as shown in FIG. 2, the first mixture layer coating process is performed on the positive electrode current collector 27. The first mixture layer coating process includes a process of forming a first positive electrode mixture coating film 23B on the positive electrode current collector 27 from a first mixture of the solid electrolyte 25 and the first positive electrode active material particles 23, and a process of deforming the surface of a portion of the first positive electrode active material particles 23 in the surface portion of the first positive electrode mixture coating film 23B by applying pressure to the first positive electrode mixture coating film 23B, thereby forming a flat surface 23C. Figure 5As shown in (a), the prepared positive electrode mixture is coated onto the positive electrode current collector 27 to form a first positive electrode mixture coating film. The coating method for the positive electrode mixture is not particularly limited; a positive electrode mixture in powder form can be used, such as a vibratory feeder, a benchtop feeder, or a screw feeder. It should be noted that a slurry obtained by dispersing the positive electrode mixture in a solvent or the like can also be coated onto the positive electrode current collector 27, and the solvent can be removed by heating or the like to form the first positive electrode mixture coating film.

[0190] Next, as Figure 5 As shown in (b), the first positive electrode additive layer 21 is formed by applying pressure to the first positive electrode additive coating film coated on the positive electrode current collector 27. In this embodiment, for example, the first positive electrode additive coating film is pressurized with a pressure load in the range of 100% to 300% of the compressive strength of one particle of the first positive electrode active material particle 23, thereby deforming a portion of the surface of the first positive electrode active material particle 23 in the surface portion of the first positive electrode additive coating film to form deformed positive electrode active material particles 23A with a flat surface 23C. By applying pressure with a load pressure within the above range, deformed positive electrode active material particles 23A can be formed well, and the breakage of the first positive electrode active material particles 23 can be suppressed. As a result, the breakage of the first positive electrode active material particles 23 can be suppressed, and deformed to form deformed positive electrode active material particles 23A. Furthermore, breakage is not easily generated in the undeformed positive electrode active material particles 23B, thus suppressing the degradation of electrode performance. Furthermore, by pressurizing the first positive electrode coating film, the gaps between the first positive electrode active material particles 23 and the solid electrolyte 25 are filled, resulting in a first positive electrode coating layer 21 with a high filling rate. The pressurization method for the first positive electrode coating film is not particularly limited; methods such as using a pressurizer can be employed.

[0191] By deforming a portion of the surface of the first positive electrode active material particles 23 in the surface portion of the first positive electrode coating film to form a flat surface 23C, when the second positive electrode coating film is coated in the second coating layer process, the particles in the second positive electrode coating film can easily flow onto the flat surface of the first positive electrode layer 21, thus forming a uniform second positive electrode layer 22. Furthermore, it is easy to achieve a state where the flat surface 23C is in contact with the second positive electrode active material particles 26.

[0192] Next, in the second coating process, a positive electrode mixture is prepared as a second mixture by mixing the desired solid electrolyte 28, the second positive electrode active material particles 26, and other components such as binders and conductive additives as needed. The specific forms of each component in this positive electrode mixture are as described for the positive electrode 50 above. The same positive electrode mixture as the first mixture can be used as the second mixture, or a different positive electrode mixture can be used.

[0193] Next, as shown in (c) of FIG. 4, the prepared positive electrode mixture is coated on the first positive electrode mixture-coated film after the pressing, to form a second positive electrode mixture-coated film. In the process of coating the second positive electrode mixture-coated film, the coating method of the positive electrode mixture is not particularly limited, and the same method as that of the first positive electrode mixture-coated film can be used. Figure 5 Next, as shown in (d) of FIG. 4, after the second positive electrode mixture-coated film is coated, the second positive electrode mixture-coated film is pressed, whereby a second positive electrode mixture layer 22 is formed, and a positive electrode 50 in which the positive electrode active material mixture layer 20 is formed on the current collector 27 can be manufactured. Note that the pressing load of the second positive electrode mixture-coated film is, for example, set to the pressure of the second positive electrode mixture layer 22 at the target packing ratio, and can be equal to or greater than the pressing load of the first positive electrode mixture-coated film, or can be less than the pressing load of the first positive electrode mixture-coated film.

[0194] Figure 5 Note that, in the case where the negative electrode 60 is manufactured as the electrode 10, the negative electrode 60 can be manufactured by using the first negative electrode active material particles 33 and the solid electrolyte 34 instead of the first positive electrode active material particles 23 and the solid electrolyte 25, and using the second negative electrode active material particles 35 and the solid electrolyte 37 instead of the second positive electrode active material particles 26 and the solid electrolyte 28 in the manufacturing method of the positive electrode 50 described above.

[0195] Note that, in the case where the negative electrode 60 is manufactured as the electrode 10, the negative electrode 60 can be manufactured by using the first negative electrode active material particles 33 and the solid electrolyte 34 instead of the first positive electrode active material particles 23 and the solid electrolyte 25, and using the second negative electrode active material particles 35 and the solid electrolyte 37 instead of the second positive electrode active material particles 26 and the solid electrolyte 28 in the manufacturing method of the positive electrode 50 described above.

[0196]

Example

[0197] Hereinafter, an example of the present embodiment will be described. Note that the examples shown below are one example, and the present embodiment is not limited to these examples.

[0198] First, a Li-containing Ni-Mn-Co composite oxide (average particle diameter: in the range of 4 μm or more and 5 μm or less, compression strength: 106 MPa) as the first positive electrode active material particles 23 and the second positive electrode active material particles 26 and calcium carbonate (average particle diameter: in the range of 0.7 μm or more and 1 μm or less) as the solid electrolyte 25 and the solid electrolyte 28 were mortar-mixed at a component ratio of positive electrode active material particles / calcium carbonate = 15 / 85 by weight, to thereby prepare a positive electrode mixture as a first mixture and a second mixture.

[0199] Next, as the positive electrode current collector 27, an aluminum foil (thickness: 20 μm) was prepared. After the above-prepared positive electrode mixture was coated on the aluminum foil using a φ 10 mm mold, the positive electrode mixture was pressed at 289 MPa, to thereby form the first positive electrode mixture layer 21.

[0200] ​On the first positive electrode mixture layer 21, the prepared positive electrode mixture was coated using a mold of φ 10 mm and then pressed, thereby forming the second positive electrode mixture layer 22, and the positive electrode 50 was completed.

[0201] Figure 6 is a cross-sectional SEM image of the positive electrode active material mixture layer 20 in the example. As shown in Figure 6 , it is understood that the positive electrode active material mixture layer 20 has a boundary 20A between the first positive electrode mixture layer 21 and the second positive electrode mixture layer 22. The film thickness of the first positive electrode mixture layer 21 is 190.7 μm. In addition, the film thickness of the second positive electrode mixture layer 22 is 193.9 μm.

[0202] Figure 7 is a cross-sectional SEM image of the boundary 20A between the first positive electrode mixture layer 21 and the second positive electrode mixture layer 22 in the example. As shown in Figure 7 , it is understood that the first positive electrode active material particles 23 that are in contact with the boundary 20A between the first positive electrode mixture layer 21 and the second positive electrode mixture layer 22 become deformed positive electrode active material particles 23A having flat surfaces 23C due to flattening by pressing toward the second positive electrode mixture layer 22. In addition, it is understood that at the boundary 20A, the deformed positive electrode active material particles 23A include particles in which the flat surfaces 23C of the deformed positive electrode active material particles 23A are in contact with the second positive electrode active material particles 26. Furthermore, the deformed positive electrode active material particles 23A include particles in which the angle A formed by the outer periphery of the deformed positive electrode active material particles 23A and the flat surfaces 23C of the deformed positive electrode active material particles 23A is 90° or more. Furthermore, the deformed positive electrode active material particles 23A include particles having an R shape, which are particles in which the surface in contact with the boundary 20A is 10 times or more the average particle diameter D of the non-deformed positive electrode active material particles 23B.

[0203] Figure 8 is a magnified cross-sectional SEM image of the positive electrode active material mixture layer 20 in the example. In Figure 8 , the boundary 20A between the first positive electrode mixture layer 21 and the second positive electrode mixture layer 22 in the cross section of the positive electrode active material mixture layer 20 is magnified. In addition, the data measured from the cross-sectional SEM image of the positive electrode active material mixture layer 20 in the example is shown in Table 1 of Figure 9 .

[0204] As shown in Table 1, the average particle size D of the undeformed positive electrode active material particles 23B contained in the first positive electrode compound layer 21 (i.e., the average particle size D of the undeformed positive electrode active material particles 23B in Table 1) is 4.03 μm, and the maximum length L of the flat surface of the undeformed positive electrode active material particles 23B is 5.98 μm. Therefore, there are deformed positive electrode active material particles 23A whose flat surface length L in the cross-sectional view is greater than or equal to the average particle size D of the undeformed positive electrode active material particles 23B. In addition, the ratio of the total length L of the flat surface of the deformed positive electrode active material particles 23A to the length B of the boundary with the second positive electrode compound layer 22, i.e., the ratio ∑L / B of the flat surface in Table 1, is 82.3%. Furthermore, the average particle spacing d between adjacent deformed positive electrode active material particles 23A (i.e., the average distance d between deformed positive electrode active material particles 23A in Table 1) is 114.2% of the average particle size D of the undeformed positive electrode active material particles 23B.

[0205] The electrodes and batteries of the present invention have been described above based on the embodiments and examples, but the present invention is not limited to these embodiments and examples. Various modifications to the embodiments and examples that can be conceived by those skilled in the art, as well as other solutions constructed by combining some of the constituent elements of the embodiments and examples, are also included within the scope of the present invention, provided they do not depart from the spirit of the invention.

[0206] Industrial availability

[0207] It is anticipated that the electrode of the present invention and the battery using the electrode will be applied to batteries for portable electronic devices and wearable electronic devices, as well as automotive batteries, etc.

Claims

1. An electrode comprising: Current collector; and The active substance mixture layer comprises a first mixture layer and a second mixture layer. The first mixture layer is located above the current collector and contains first particles and first active substance particles. The second mixture layer is located above the first mixture layer and contains second particles and second active substance particles. In a cross-sectional view of the electrode, the active substance mixture layer has at least a portion of a boundary between the first mixture layer and the second mixture layer where the first active substance particles and the second active substance particles are connected in a discontinuous state. wherein The first active substance particles comprise: deformable particles having a flat surface facing the second compound layer at the boundary, and non-deformable particles not having the flat surface.

2. The electrode of claim 1, wherein, At the boundary, the flat surface of the deformed particle is in contact with the second active material particle.

3. The electrode according to claim 1 or 2, wherein, The deformable particles are those whose length in the cross-sectional view of the electrode is greater than or equal to the average particle size of the non-deformable particles.

4. The electrode according to claim 1 or 2, wherein, The deformable particles are those in a cross-sectional view of the electrode in which the angle between the outer periphery of the deformable particle and the flat surface of the deformable particle is greater than 90°.

5. The electrode according to claim 1 or 2, wherein, In a cross-sectional view of the electrode, the total length of the flat surface at the boundary is more than 80% of the length of the boundary.

6. The electrode according to claim 1 or 2, wherein The average interparticle spacing between the deformable particles at the boundary is less than 130% of the average particle diameter of the undeformable particles.

7. The electrode according to claim 1 or 2, wherein The average particle size of the first particle is less than 50% relative to the average particle size of the undeformed particles.

8. The electrode according to claim 1 or 2, wherein, In a cross-sectional view of the electrode, the first particles are attached to more than 80% of the surface of the first active material particles.

9. The electrode according to claim 1 or 2, wherein, The thickness of the first compound layer is in the range of 20 μm or more and 200 μm or less.

10. The electrode according to claim 1 or 2, wherein, The first particle and the second particle are solid electrolytes.

11. A battery comprising a positive electrode, a negative electrode, and an electrolyte layer located between the positive electrode and the negative electrode. At least one of the positive electrode and the negative electrode is an electrode as described in any one of claims 1 to 10.

12. A method for manufacturing the electrode according to claim 1, comprising: A first mixture of first particles and first active substance particles forms a first agent coating film on the current collector; By applying pressure to the first compound coating film, a portion of the surface of the first active substance particles in the surface portion of the first compound coating film is deformed to form a flat surface; as well as A second mixture of second particles and second active substance particles is formed on the first mixture coating film after pressurization to form a second mixture coating film.

13. The method of manufacturing an electrode according to claim 12, wherein, The average particle size of the first active material particles is less than 50% of the average particle size of the first active material particles.

14. The method of manufacturing an electrode according to claim 12 or 13, wherein Also includes: The first active material particle and the first particle are mixed in such a way that more than 80% of the first particle adheres to the surface of the first active material particle, thereby preparing the first mixture.

15. The method of manufacturing an electrode according to claim 12 or 13, wherein, The pressure load on the first compound coating film is within the range of 100% to 300% of the compressive strength of one particle of the first active substance particle.

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