Electrode current collector, bipolar battery, all-solid-state battery, and method for manufacturing electrode current collector

Abstract

To provide an electrode collector which has a reduced metal amount.SOLUTION: An electrode collector contains a metallic foil, a conductive resin layer, and a carbon particle layer in this order. The conductive resin layer contains a continuous phase and a dispersion phase. The continuous phase contains a resin material. The dispersion phase contains conductive particles. The carbon particle layer contains conductive carbon particles.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to an electrode current collector, a bipolar battery, a all-solid-state battery, and a method for manufacturing an electrode current collector.

Background Art

[0002] JP 2019-106282 A (Patent Document 1) discloses a resin current collector.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Conventionally, metal foils have been used as electrode current collectors. For example, from the viewpoints of reducing material costs and mass energy density, etc., reduction of the amount of metal has been demanded. For example, as an alternative to metal foils, resin current collectors have been proposed. However, when metal foils are replaced with resin current collectors, the battery resistance tends to increase.

[0005] An object of the present disclosure is to provide an electrode current collector with a reduced amount of metal.

Means for Solving the Problems

[0006] Hereinafter, the technical configuration and effects of the present disclosure will be described. However, the mechanism of action in this specification includes assumptions. The mechanism of action does not limit the technical scope of the present disclosure.

[0007] 1. The electrode current collector includes a metal foil, a conductive resin layer, and a carbon particle layer in this order. The conductive resin layer includes a continuous phase and a dispersed phase. The continuous phase includes a resin material. The dispersed phase includes conductive particles. The carbon particle layer includes conductive carbon particles.

[0008] By replacing a part of the metal foil with a conductive resin layer, a reduction in the amount of metal is expected. The conductive resin layer includes a continuous phase (resin material) and a dispersed phase (conductive particles). In the thickness direction, the conductive resin layer can have sufficient conductivity. However, according to the new findings of the present disclosure, since the in-plane variation of the resistance on the surface of the conductive resin layer is large, spots of electrode reaction can occur. The spots of electrode reaction can contribute to an increase in battery resistance.

[0009] In the present disclosure, a carbon particle layer covers the conductive resin layer. It is expected that electrons are evenly distributed within the carbon particle layer. Thereby, it is expected that the in-plane variation of the resistance is significantly reduced.

[0010] 2. In the electrode current collector described in the above "1", the metal foil may be an aluminum foil. The resin material may be an olefin-based resin.

[0011] 3. In the electrode current collector described in the above "1" or "2", the metal foil may have a thickness of, for example, 20 to 40 μm. The conductive resin layer may have a thickness of, for example, 5 to 20 μm. The carbon particle layer may have a thickness of, for example, 0.5 to 5 μm.

[0012] 4. In the electrode current collector described in any one of the above "1" to "3", the conductive resin layer may contain, by mass fraction, 5 to 30% of conductive particles and the balance of the resin material. The carbon particle layer may contain, by mass fraction, 50% or more of conductive carbon particles.

[0013] 5. In the electrode current collector described in any one of the above "1" to "4", the conductive particles may contain at least one selected from the group consisting of conductive carbon particles and metal particles.

[0014] 6. In the current collector electrode according to any one of the above items “1” to “5”, the conductive particles may contain at least one selected from the group consisting of acetylene black, furnace black, graphite, vapor-grown carbon fiber, carbon nanotube, carbon nanofiber, carbon nanosphere, nickel particles, tin particles, copper particles, nickel-tin alloy particles, copper-tin alloy particles, and copper-nickel alloy particles.

[0015] 7. In the current collector electrode according to any one of the above items “1” to “6”, on the surface of the carbon particle layer, the current mapping result measured by a scanning probe microscope may have a standard deviation of 0.3 nA or less. The current mapping result is measured by an applied voltage of 10 V in a measurement region of 80 μm square.

[0016] The in-plane variation of resistance can be evaluated by a scanning probe microscope (SPM). By SPM, current mapping is measured. It is considered that the smaller the variation (standard deviation) of the current, the smaller the in-plane variation of the resistance. The carbon particle layer can have a standard deviation of 0.3 nA or less. On the other hand, the conductive resin layer can have a standard deviation exceeding 1 nA.

[0017] 8. The bipolar battery includes the current collector electrode according to any one of the above items “1” to “7”.

[0018] Conventionally, a clad foil has been used as the current collector electrode for a bipolar battery. The clad foil can be formed by laminating an Al foil and a Cu foil. The Al foil can correspond to the positive electrode. The Cu foil can correspond to the negative electrode.

[0019] The current collector electrode described in the above item "1" is suitable for bipolar batteries. This is because the conductive resin layer can serve as an alternative to the Cu foil. The conductive resin layer can block the penetration of the liquid electrolyte (electrolyte solution) from the negative electrode side. By protecting the metal foil from the negative electrode with the conductive resin layer, the progress of unfavorable reactions can be suppressed. Examples of unfavorable reactions include, for example, the alloying of the metal foil and Li. By replacing the Cu foil with the conductive resin layer, the metal content can be reduced.

[0020] 9. The all-solid-state battery includes the current collector electrode according to any one of the above items "1" to "7".

[0021] The current collector electrode described in the above item "1" is also suitable for all-solid-state batteries. The all-solid-state battery may be a bipolar battery or a monopolar battery. Note that a monopolar battery may also be referred to as a unipolar battery.

[0022] 10. The method for manufacturing the current collector electrode includes the following steps (a) to (c) in this order. (a) A resin composition is formed by mixing a resin material and conductive particles. (b) A conductive resin layer is formed by directly laminating a melt of the resin composition onto a metal foil by an extrusion lamination method. (c) A carbon particle layer is formed by applying conductive carbon particles to the conductive resin layer.

[0023] Conventionally, for example, a clad foil has been manufactured by adhering an Al foil and a Cu foil with a conductive adhesive. In the manufacturing method described in the above item "10", the conductive resin layer can be directly laminated onto the metal foil. That is, the conductive adhesive can be reduced.

[0024] Hereinafter, embodiments of the present disclosure (hereinafter may be abbreviated as "the present embodiments"), and examples of the present disclosure (hereinafter may be abbreviated as "the present examples") will be described. However, the present embodiments and the present examples do not limit the technical scope of the present disclosure. The present embodiments and the present examples are illustrative in all respects. The present embodiments and the present examples are non-limiting. The technical scope of the present disclosure includes all modifications within the meaning and scope equivalent to the description of the claims. For example, any configurations are extracted from the present embodiments and the present examples, and their arbitrary combinations are also initially planned.

Brief Description of the Drawings

[0025]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Modes for Carrying Out the Invention

[0026] <<Terms, Definitions, etc.>> The descriptions of "comprise", "include", "have", and their variants (such as "consisting of", etc.) are in an open-ended form. The open-ended form may further include additional elements in addition to the essential elements, or may not include them. The description of "consisting of" is in a closed form. However, even in the closed form, additional elements that are normally accompanying impurities or are irrelevant to the disclosed technology are not excluded. The description of "substantially consisting of" is in a semi-closed form. In the semi-closed form, the addition of elements that do not substantially affect the basic and novel characteristics of the disclosed technology is allowed.

[0027] Expressions such as "may" and "can" are used in an allowable sense, meaning "having the possibility of doing", rather than in an obligatory sense, meaning "must do".

[0028] Unless otherwise specified, the execution order of the multiple steps, operations, and actions included in various methods is not limited to the order of description. For example, multiple steps may proceed simultaneously. For example, multiple steps may proceed sequentially.

[0029] "At least one of A and B" includes "A or B" as well as "A and B". "At least one of A and B" may also be denoted as "A and / or B".

[0030] Elements expressed in the singular form include the plural form as well, unless otherwise specified. For example, "particle" includes not only "one particle" but also "a plurality of particles (particle group)" and "an aggregate of particles (powder, powder)".

[0031] Geometric terms (such as "parallel", "perpendicular", "orthogonal", etc.) should not be construed in a strict sense. For example, "parallel" may deviate somewhat from "parallel" in the strict sense. Geometric terms may include, for example, tolerances, errors, etc. in design, operation, manufacturing, etc. The dimensional relationships in each figure may not match the actual dimensional relationships. For the purpose of assisting the reader's understanding, the dimensional relationships (length, width, thickness, etc.) in each figure may be changed. Furthermore, some components may be omitted.

[0032] Numerical ranges such as "m~n%" include the upper and lower limit values unless otherwise specified. That is, "m~n%" indicates a numerical range of "m% or more and n% or less". Also, "m% or more and n% or less" includes "more than m% and less than n%". Furthermore, a numerically arbitrarily selected value within the numerical range may be used as a new upper or lower limit value. For example, a new numerical range may be set by arbitrarily combining a value within the numerical range with a value described in another part of this specification, in a table, in a figure, etc.

[0033] All numerical values are modified by the term "about". The term "about" may mean, for example, ±5%, ±3%, ±1%, etc. All numerical values may be approximate values that can vary depending on the form of utilization of the disclosed technology. All numerical values may be expressed in significant figures. A measured value may be, unless otherwise specified, an average value in multiple measurements. The number of measurements may be 3 or more, 5 or more, or 10 or more. Generally, the greater the number of measurements, the more reliable the average value is expected to be. A measured value may be rounded off based on the number of significant figures. A measured value may include errors associated with, for example, the detection limit of the measuring device.

[0034] The stoichiometric composition formula represents a representative example of a compound. The compound may have a non-stoichiometric composition. For example, "Al2O3" is not limited to a compound having a molar ratio of "Al / O = 2 / 3". Unless otherwise specified, "Al2O3" represents a compound containing Al and O in any composition ratio. Further, for example, the compound may be doped with trace elements, or a part of Al and O may be substituted with another element.

[0035] "Derivative" refers to a compound modified by at least one selected from the group consisting of introduction of a substituent, substitution of an atom, oxidation, reduction, and other chemical reactions in a part of the parent compound. The modification site may be one or a plurality of sites. "Substituent" includes, for example, at least one selected from the group consisting of an alkyl group, an alkenyl group, an alkynyl group, a cycloalkyl group, an unsaturated cycloalkyl group, an aromatic group, a heterocyclic group, a halogen atom (F, Cl, Br, I, etc.), an OH group, an SH group, a CN group, an SCN group, an OCN group, a nitro group, an alkoxy group, an unsaturated alkoxy group, an amino group, an alkylamino group, a dialkylamino group, an aryloxy group, an acyl group, an alkoxycarbonyl group, an acyloxy group, an aryloxycarbonyl group, an acylamino group, an alkoxycarbonylamino group, an aryloxycarbonylamino group, a sulfonylamino group, a sulfamoyl group, a carbamoyl group, an alkylthio group, an arylthio group, a sulfonyl group, a sulfinyl group, a ureido group, a phosphoric acid amide group, a sulfo group, a carboxy group, a hydroxamic acid group, a sulfino group, a hydrazino group, an imino group, and a silyl group, etc. These substituents may be further substituted. When there are two or more substituents, the substituents may be the same or different. A plurality of substituents may be bonded to each other to form a ring. Note that a derivative of a polymer compound (resin material) may also be referred to as a "modified product".

[0036] "Copolymer" includes at least one selected from the group consisting of a non-specific type, a statistical type, a random type, an alternating type, a periodic type, a block type, and a graft type.

[0037] "D50" indicates the particle size at which the cumulative frequency from the smaller particle size side reaches 50% in the volume-based particle size distribution. D50 can be measured by the laser diffraction method.

[0038] "Coating weight" indicates the mass of the coating film (coated layer) per unit area.

[0039] "Electrode" is a general term for the positive electrode and the negative electrode. Therefore, for example, electrode active material is a general term for the positive electrode active material and the negative electrode active material. For example, electrode active material layer is a general term for the positive electrode active material layer and the negative electrode active material layer. Electrode may also indicate at least one of the positive electrode and the negative electrode. Electrode may also indicate a bipolar electrode.

[0040] <<Current collector for electrode>> FIG. 1 is a conceptual diagram showing the current collector for electrode in this embodiment. The current collector for electrode 10 is in a sheet form. The current collector for electrode 10 exchanges electrons with the electrode active material layer. The current collector for electrode 10 includes a metal foil 11, a conductive resin layer 12, and a first carbon particle layer 13a in this order. The current collector for electrode 10 may further include, for example, a second carbon particle layer 13b. The current collector for electrode 10 may include, for example, a second carbon particle layer 13b, a metal foil 11, a conductive resin layer 12, and a first carbon particle layer 13a in this order. Hereinafter, the "first carbon particle layer" and the "second carbon particle layer" may be collectively referred to as the "carbon particle layer".

[0041] <Metal foil> The metal foil 11 may be, for example, the base material of the electrode current collector 10. The metal foil 11 has a first thickness T1. The first thickness T1 may be, for example, 10 to 100 μm, or 20 to 40 μm. The metal foil 11 may be, for example, a pure metal foil or an alloy foil. The metal foil 11 may contain at least one selected from the group consisting of, for example, Al, Mn, Ti, Fe, and Cr. The metal foil 11 may be, for example, an Al foil, an Al alloy foil, a Ti foil, or a stainless steel (SUS) foil, etc. The metal foil 11 may be, for example, alloy numbers "1085", "1070", "1050", "1N30", "1100", "3003", "3004", "8021", "8079", etc. defined in "JIS H 4160: Aluminum and Aluminum Alloy Foil". Rolling, annealing, etc. may be performed on the metal foil.

[0042] The metal foil 11 includes a first main surface 11a and a second main surface 11b. The second main surface 11b is the opposite surface of the first main surface 11a. A conductive resin layer 12 is laminated on the first main surface 11a. The second main surface 11b may be exposed. A second carbon particle layer 13b may cover the second main surface 11b.

[0043] <Conductive Resin Layer> The conductive resin layer 12 is laminated on the first main surface 11a. The conductive resin layer 12 may be directly laminated on the first main surface 11a. The conductive resin layer 12 has a second thickness T2. The second thickness T2 may be, for example, thinner than the first thickness T1. That is, the relationship of "T2 ≦ T1" may be satisfied. The second thickness T2 may be, for example, 10 to 100 μm, or 5 to 20 μm.

[0044] The conductive resin layer 12 may be, for example, non-porous. The conductive resin layer 12 may be impermeable to liquids. The conductive resin layer 12 includes a continuous phase and a dispersed phase. The continuous phase includes a resin material. The continuous phase may also be referred to as, for example, a "matrix resin", etc. The dispersed phase includes conductive particles. The dispersed phase can impart conductivity to the conductive resin layer 12. The conductive particles may also be referred to as, for example, "conductive fillers", etc.

[0045] The conductive resin layer 12 may contain, for example, 1 to 40% of conductive particles and the balance of resin material by mass fraction. The mass fraction of the conductive particles may be, for example, 5 to 30%, or 10 to 25%.

[0046] The conductive resin layer 12 may contain, for example, 0.1 to 20% of conductive particles and the balance of resin material by volume fraction. The volume fraction of the conductive particles may be, for example, 1 to 5%, or 5 to 15%.

[0047] The resin material may contain any components. The resin material may be insoluble in the electrolyte of the battery, for example. The resin material may contain at least one selected from the group consisting of, for example, olefin resins, urethane resins, polyamide resins, cellulose resins, polyether resins, acrylic resins, and polyester resins. The resin material may contain at least one selected from the group consisting of, for example, polyethylene (PE), polypropylene (PP), polyvinylidene fluoride (PVdF), polytetrafluoroethylene (PTFE), polyamide (PA), polyamideimide (PAI), polyimide (PI), aromatic polyamide (aramid), liquid crystal polyester, polyacrylate ester, polymethacrylate ester, polystyrene, AS resin, ABS resin, polyphenylene ether (PPE), silicone resin, and modified products thereof. The modified product may be, for example, a maleic acid modified product. By modification, for example, adhesiveness or the like may be enhanced. PE may contain, for example, LLDPE (Linear Low Density Polyethylene), HDPE (High Density Polyethylene), etc. For example, from the viewpoints of resistance to the electrolyte, moldability, etc., LLDPE is suitable for the resin material.

[0048] The conductive particles can have any shape. The conductive particles may be, for example, spherical, needle-shaped, plate-shaped, etc. The conductive particles may have a D50 of, for example, 1 to 15 μm, 1 to 10 μm, or 2 to 5 μm. The conductive particles have electronic conductivity. The conductive particles may contain at least one selected from the group consisting of, for example, conductive carbon particles and metal particles. The conductive particles may contain at least one selected from the group consisting of, for example, carbon black, graphite, vapor-grown carbon fiber (VGCF), carbon nanotube (CNT), carbon nanofiber (CNF), carbon nanosphere (CNS), Ni particles, Sn particles, Cu particles, Ni-Sn alloy particles, Cu-Sn alloy particles, and Cu-Ni alloy particles. The carbon black may contain at least one selected from the group consisting of, for example, acetylene black (AB), ketjen black (registered trademark), furnace black, channel black, lamp black, and thermal black.

[0049] Figure 2 is Table 1 showing the evaluation results of the conductive particles. The volume resistivity of the conductive resin layer 12 is measured by the following procedure. A sample is cut out from the conductive resin layer 12. The resistance of the sample is measured with the sample sandwiched between two Cu electrodes. The Cu electrodes are cylindrical (diameter: 20 mm). The resistance of the sample includes a component of contact resistance. The component of contact resistance is subtracted from the resistance of the sample. The area resistivity is obtained by multiplying the resistance after subtraction by the area of the Cu electrode. The volume resistivity is obtained by dividing the area resistivity by the thickness of the sample (conductive resin layer 12).

[0050] All of the conductive resin layers 12 in Table 1 contain the same resin material (modified olefin resin). The conductive resin layer containing AB and Ni particles tends to have a low volume resistivity. The conductive resin layer 12 may have a volume resistivity of, for example, 1 to 1000 Ω·cm, 5 to 500 Ω·cm, or 10 to 50 Ω·cm.

[0051] <First Carbon Particle Layer> The first carbon particle layer 13a covers the conductive resin layer 12. The first carbon particle layer 13a has a third thickness T3. The third thickness T3 may be, for example, thinner than the second thickness T2. That is, the relationship of "T3≦T2≦T1" may be satisfied. The third thickness T3 may be, for example, 0.1 to 5 μm, 0.3 to 3 μm, or 0.5 to 1.5 μm. The first carbon particle layer 13a may have, for example, a basis weight of 5 mg / cm 2 as follows. The basis weight of the first carbon particle layer 13a may be, for example, 0.1 to 3 mg / cm 2 , or 0.5 to 1.5 mg / cm 2 .

[0052] The first carbon particle layer 13a may be, for example, porous. The first carbon particle layer 13a contains conductive carbon particles. For example, the first carbon particle layer 13a may contain 50% or more of conductive carbon particles by mass fraction. The first carbon particle layer 13a may further contain a binder. For example, the first carbon particle layer 13a may contain 50% or more of conductive carbon particles and the balance of the binder by mass fraction. The mass fraction of the conductive carbon particles may be, for example, 75 to 99% or 80 to 95%.

[0053] The conductive carbon particles have electron conductivity. The conductive carbon particles may contain, for example, at least one selected from the group consisting of carbon black, graphite, VGCF, graphene flakes (GF), CNT, CNF, and CNS.

[0054] The binder can fix the conductive carbon particles to the conductive resin layer 12. The binder in the first carbon particle layer 13a is a dispersed phase. The binder is not a continuous phase. The binder may contain any component. The binder may contain, for example, at least one selected from the group consisting of PVdF, PTFE, carboxymethyl cellulose (CMC), and polyacrylic acid (PAA).

[0055] The first carbon particle layer 13a can reduce the in-plane variation of resistance on the surface of the conductive resin layer 12. The in-plane variation of resistance can be evaluated by SPM. The evaluation procedure is as follows. A sample is cut out from the electrode current collector 10. By SPM, current mapping is measured in the first carbon particle layer 13a. For example, an atomic force microscope "Product name: Dimension Icon (registered trademark)" manufactured by Bruker and a controller "Product name: NanoScope V" etc. may be used. The measurement area is 80 μm square (a square of 80 μm × 80 μm). The applied voltage is 10 V. From the current mapping result, the standard deviation of the current at all pixels (measurement points) is obtained. The smaller the standard deviation, the smaller the in-plane variation of resistance is considered. The standard deviation may be, for example, 0.3 nA or less, 0.2 nA or less, or 0.15 nA or less. The standard deviation can vary depending on, for example, the structure (thickness, porosity), composition, etc. of the first carbon particle layer 13a. The first carbon particle layer 13a may be formed so that the standard deviation becomes 0.3 nA or less. The standard deviation of the current in the conductive resin layer 12 may exceed 1 nA, for example.

[0056] <The second carbon particle layer> The second carbon particle layer 13b covers the second main surface 11b. The second carbon particle layer 13b may have the same configuration as the first carbon particle layer 13a, or may have a different configuration. For example, the second carbon particle layer 13b may be thicker or thinner than the first carbon particle layer 13a. For example, the second carbon particle layer 13b may have a higher or lower mass fraction of conductive carbon particles than the first carbon particle layer 13a.

[0057] <<Method for manufacturing an electrode current collector>> FIG. 3 is a schematic flowchart of the method for manufacturing an electrode current collector in the present embodiment. Hereinafter, "the method for manufacturing an electrode current collector in the present embodiment" may be abbreviated as "the present manufacturing method". The present manufacturing method includes "(a) formation of a resin composition", "(b) direct lamination", and "(c) formation of a carbon particle layer".

[0058] <(a) Formation of a resin composition> This manufacturing method includes forming a resin composition by mixing a resin material and conductive particles. The resin composition may also be referred to as, for example, a "compound". The resin composition may be in the form of pellets, for example. The resin composition can be formed by any method. For example, melt-kneading may be carried out. For example, melt-kneading may be carried out using a twin-screw extrusion kneader.

[0059] <(b) Direct Lamination> This manufacturing method includes forming a conductive resin layer 12 by directly laminating a melt of the resin composition onto a metal foil 11 by an extrusion lamination method. Such a process may also be referred to as "direct lamination". An adhesive is not required in direct lamination. For example, an extrusion laminator may be used. A melt of the resin composition can be formed. A resin film can be formed by extruding the melt in a film shape from a T-die. The resin film and the metal foil 11 are passed through a roll gap, whereby the conductive resin layer 12 can be laminated on the metal foil 11 (first main surface 11a). After lamination, the conductive resin layer 12 may be cooled.

[0060] <(c) Formation of Carbon Particle Layer> This manufacturing method includes forming a first carbon particle layer 13a by applying conductive carbon particles to the conductive resin layer 12. For example, a coating liquid may be formed by mixing conductive carbon particles, a binder, and a dispersion medium. The dispersion medium can be selected according to the type of binder, etc. The dispersion medium may contain, for example, N-methyl-2-pyrrolidone (NMP). For example, the coating liquid may be applied to the conductive resin layer 12 by a gravure coating method. The gravure coating method is suitable for forming a thin coating film (for example, with a thickness of 5 μm or less). The first carbon particle layer 13a can be formed by drying the coating liquid. That is, the electrode current collector 10 can be completed.

[0061] This manufacturing method may further include, for example, forming a second carbon particle layer 13b on the second main surface 11b of the metal foil 11. The second carbon particle layer 13b can be formed in the same manner as the first carbon particle layer 13a.

[0062] <<Bipolar battery>> The electrode current collector 10 may be, for example, for a bipolar battery. FIG. 4 is a conceptual diagram showing the bipolar battery in this embodiment. The bipolar battery 100 includes a power generation element 50. The bipolar battery 100 may include a liquid electrolyte (not shown). The bipolar battery 100 may include a gel electrolyte (not shown).

[0063] <Outer package> The bipolar battery 100 may include an outer package (not shown). The outer package may house the power generation element 50 and the liquid electrolyte. The outer package can have any form. The outer package may be, for example, a metal case, or a pouch made of a metal foil laminate film or the like. The outer package may include, for example, Al or the like.

[0064] <Power generation element> The power generation element 50 may also be referred to as an "electrode group", an "electrode body", etc. The power generation element 50 includes bipolar electrodes 20 and separators 30. The power generation element 50 can be formed by alternately laminating the bipolar electrodes 20 and the separators 30.

[0065] The bipolar electrode 20 includes an electrode current collector 10, a positive electrode active material layer 21, and a negative electrode active material layer 22. That is, the bipolar battery 100 includes the electrode current collector 10. The positive electrode active material layer 21 is disposed on the second main surface 11b side. The positive electrode active material layer 21 may be directly formed on the second main surface 11b. A second carbon particle layer 13b may be interposed between the positive electrode active material layer 21 and the second main surface 11b (metal foil 11). The negative electrode active material layer 22 is disposed on the first main surface 11a side. A first carbon particle layer 13a is interposed between the negative electrode active material layer 22 and the conductive resin layer 12.

[0066] <Positive electrode active material layer> The positive electrode active material layer 21 may have a thickness of, for example, 10 to 1000 μm, 50 to 500 μm, or 100 to 300 μm. The positive electrode active material layer 21 contains a positive electrode active material. The positive electrode active material layer 21 may further contain, for example, a conductive material and a binder.

[0067] 《Conductive material》 The conductive material can form an electron conduction path in the positive electrode active material layer 21. The compounding amount of the conductive material may be, for example, 0.1 to 10 parts by mass with respect to 100 parts by mass of the positive electrode active material. The conductive material may contain any component. The conductive material may contain at least one selected from the group consisting of graphite, AB, Ketjen black, VGCF, CNT, and GF.

[0068] 《Binder》 The binder can fix the positive electrode active material layer 21 to the electrode current collector 10. The compounding amount of the binder may be, for example, 0.1 to 10 parts by mass with respect to 100 parts by mass of the positive electrode active material. The binder may contain any component. The binder may contain at least one selected from the group consisting of PVdF, vinylidene fluoride - hexafluoropropylene copolymer (PVdF - HFP), PTFE, CMC, PAA, polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), polyoxyethylene alkyl ether, and derivatives thereof.

[0069] 《Other components》 The positive electrode active material layer 21 may further contain, for example, an inorganic filler, an organic filler, a solid electrolyte, a surface modifier, a dispersant, a lubricant, a flame retardant, a protective agent, a flux, a coupling agent, an adsorbent, etc. The positive electrode active material layer 21 may contain, for example, polyoxyethylene allyl phenyl ether phosphate, zeolite, silane coupling agent, MoS2, WO3, etc.

[0070] 《Positive electrode active material》 The positive electrode active material may be, for example, particulate. The positive electrode active material may have a D50 of, for example, 1 to 30 μm, 10 to 20 μm, or 1 to 10 μm. The positive electrode active material may contain any components. The positive electrode active material may contain, for example, a transition metal oxide, a polyanion compound, etc. Within one particle (positive electrode active material), the composition may be uniform or non-uniform. For example, the composition may be inclined from the surface of the particle toward the center. The composition may change continuously or discontinuously (stepwise).

[0071] 〈Transition metal oxide: Space group R-3m〉 The transition metal oxide may have any crystal structure. The transition metal oxide may contain, for example, a crystal structure belonging to the space group R-3m. For example, a compound represented by the general formula "LiMO2" may have a crystal structure belonging to the space group R-3m. The transition metal oxide may be represented, for example, by the following formula (1-1).

[0072] Li 1-a Ni x M 1-x O2…(1-1) In the formula, the relationship of -0.5 ≦ a ≦ 0.5 and 0 ≦ x ≦ 1 is satisfied. M may contain at least one selected from the group consisting of, for example, Co, Mn, and Al.

[0073] In the above formula (1-1), x may satisfy, for example, the relationship of 0 < x ≦ 0.1, 0.1 ≦ x ≦ 0.2, 0.2 ≦ x ≦ 0.3, 0.3 ≦ x ≦ 0.4, 0.4 ≦ x ≦ 0.5, 0.5 ≦ x ≦ 0.6, 0.6 ≦ x ≦ 0.7, 0.7 ≦ x ≦ 0.8, 0.8 ≦ x ≦ 0.9, or 0.9 ≦ x ≦ 1. a may satisfy, for example, the relationship of -0.4 ≦ a ≦ 0.4, -0.3 ≦ a ≦ 0.3, -0.2 ≦ a ≦ 0.2, or -0.1 ≦ a ≦ 0.1.

[0074] The transition metal oxide is, for example, LiCoO2, LiMnO2, LiNi 0.9 Co 0.1 O2, LiNi 0.9Mn 0.1 It may also contain at least one selected from the group consisting of O2 and LiNiO2.

[0075] 〈NCM〉 The transition metal oxide may be represented, for example, by the following formula (1-2). The compound represented by the following formula (1-2) may also be referred to as "NCM".

[0076] Li 1-a Ni x Co y Mn z O2…(1-2) In the formula, the relationships of -0.5 ≦ a ≦ 0.5, 0 < x < 1, 0 < y < 1, 0 < z < 1, and x + y + z = 1 are satisfied.

[0077] In the above formula (1-2), x may satisfy, for example, the relationship of 0 < x ≦ 0.1, 0.1 ≦ x ≦ 0.2, 0.2 ≦ x ≦ 0.3, 0.3 ≦ x ≦ 0.4, 0.4 ≦ x ≦ 0.5, 0.5 ≦ x ≦ 0.6, 0.6 ≦ x ≦ 0.7, 0.7 ≦ x ≦ 0.8, 0.8 ≦ x ≦ 0.9, or 0.9 ≦ x < 1.

[0078] In the above formula (1-2), y may satisfy, for example, the relationship of 0 < y ≦ 0.1, 0.1 ≦ y ≦ 0.2, 0.2 ≦ y ≦ 0.3, 0.3 ≦ y ≦ 0.4, 0.4 ≦ y ≦ 0.5, 0.5 ≦ y ≦ 0.6, 0.6 ≦ y ≦ 0.7, 0.7 ≦ y ≦ 0.8, 0.8 ≦ y ≦ 0.9, or 0.9 ≦ y < 1.

[0079] In the above formula (1-2), z may satisfy, for example, the relationship of 0 < z ≦ 0.1, 0.1 ≦ z ≦ 0.2, 0.2 ≦ z ≦ 0.3, 0.3 ≦ z ≦ 0.4, 0.4 ≦ z ≦ 0.5, 0.5 ≦ z ≦ 0.6, 0.6 ≦ z ≦ 0.7, 0.7 ≦ z ≦ 0.8, 0.8 ≦ z ≦ 0.9, or 0.9 ≦ z < 1.

[0080] NCM is, for example, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2, LiNi 0.4 Co 0.3 Mn 0.3O2, LiNi 0.3 Co 0.4 Mn 0.3 O2, LiNi 0.3 Co 0.3 Mn 0.4 O2, LiNi 0.5 Co 0.2 Mn 0.3 O2, LiNi 0.5 Co 0.3 Mn 0.2 O2, LiNi 0.5 Co 0.4 Mn 0.1 O2, LiNi 0.5 Co 0.1 Mn 0.4 O2, LiNi 0.6 Co 0.2 Mn 0.2 O2, LiNi 0.6 Co 0.3 Mn 0.1 O2, LiNi 0.6 Co 0.1 Mn 0.3 O2, LiNi 0.7 Co 0.1 Mn 0.2 O2, LiNi 0.7 Co 0.2 Mn 0.1 O2, LiNi 0.8 Co 0.1 Mn 0.1 O2 and LiNi 0.9 Co 0.05 Mn 0.05 It may contain at least one selected from the group consisting of O2.

[0081] 〈NCA〉 The transition metal oxide may be represented, for example, by the following formula (1-3). The compound represented by the following formula (1-3) may also be referred to as "NCA".

[0082] Li 1-a Ni x Co y Al z O2…(1-3) In the formula, the relationships of -0.5 ≦ a ≦ 0.5, 0 < x < 1, 0 < y < 1, 0 < z < 1, and x + y + z = 1 are satisfied.

[0083] In the above formula (1-3), x may satisfy a relationship such as 0 < x ≤ 0.1, 0.1 ≤ x ≤ 0.2, 0.2 ≤ x ≤ 0.3, 0.3 ≤ x ≤ 0.4, 0.4 ≤ x ≤ 0.5, 0.5 ≤ x ≤ 0.6, 0.6 ≤ x ≤ 0.7, 0.7 ≤ x ≤ 0.8, 0.8 ≤ x ≤ 0.9, or 0.9 ≤ x < 1.

[0084] In the above formula (1-3), y may satisfy a relationship such as 0 < y ≤ 0.1, 0.1 ≤ y ≤ 0.2, 0.2 ≤ y ≤ 0.3, 0.3 ≤ y ≤ 0.4, 0.4 ≤ y ≤ 0.5, 0.5 ≤ y ≤ 0.6, 0.6 ≤ y ≤ 0.7, 0.7 ≤ y ≤ 0.8, 0.8 ≤ y ≤ 0.9, or 0.9 ≤ y < 1.

[0085] In the above formula (1-3), z may satisfy a relationship such as 0 < z ≤ 0.1, 0.1 ≤ z ≤ 0.2, 0.2 ≤ z ≤ 0.3, 0.3 ≤ z ≤ 0.4, 0.4 ≤ z ≤ 0.5, 0.5 ≤ z ≤ 0.6, 0.6 ≤ z ≤ 0.7, 0.7 ≤ z ≤ 0.8, 0.8 ≤ z ≤ 0.9, or 0.9 ≤ z < 1.

[0086] NCA is, for example, LiNi 0.7 Co 0.1 Al 0.2 O2, LiNi 0.7 Co 0.2 Al 0.1 O2, LiNi 0.8 Co 0.1 Al 0.1 O2, LiNi 0.8 Co 0.17 Al 0.03 O2, LiNi 0.8 Co 0.15 Al 0.05 O2, and at least one selected from the group consisting of LiNi 0.9 Co 0.05 Al 0.05 O2 may be included.

[0087] 〈Multi-component system〉 The positive electrode active material may include, for example, two or more types of NCM or the like. The positive electrode active material may include, for example, NCM(0.6≦x) and NCM(x<0.6). "NCM(0.6≦x)" refers to a compound in which x (Ni ratio) is 0.6 or more in the above formula (1-2). NCM(0.6≦x) may be referred to as, for example, a "high nickel material". NCM(0.6≦x) includes, for example, LiNi 0.8 Co 0.1 Mn 0.1 O2 and the like. "NCM(x<0.6)" refers to a compound in which x (Ni ratio) is less than 0.6 in the above formula (1-2). NCM(x<0.6) includes, for example, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 and the like. The mixing ratio (mass ratio) of NCM(0.6≦x) and NCM(x<0.6) may be, for example, "NCM(0.6≦x) / NCM(x<0.6)=9 / 1~1 / 9", "NCM(0.6≦x) / NCM(x<0.6)=9 / 1~4 / 6", or "NCM(0.6≦x) / NCM(x<0.6)=9 / 1~3 / 7".

[0088] The positive electrode active material may include, for example, NCA and NCM. The mixing ratio (mass ratio) of NCA and NCM may be, for example, "NCA / NCM=9 / 1~1 / 9", "NCA / NCM=9 / 1~4 / 6", or "NCA / NCM=9 / 1~3 / 7". The Ni ratio may be the same or different between NCA and NCM. The Ni ratio of NCA may be higher than the Ni ratio of NCM. The Ni ratio of NCA may be lower than the Ni ratio of NCM.

[0089] 〈Transition metal oxide: Space group C2 / m〉 The transition metal oxide may include, for example, a crystal structure belonging to the space group C2 / m. The transition metal oxide may be represented by, for example, the following formula (1-4).

[0090] Li2MO3…(1-4) In the formula, M may include at least one selected from the group consisting of, for example, Ni, Co, Mn, and Fe.

[0091] The positive electrode active material may contain, for example, a mixture of LiMO2 (space group R-3m) and Li2MO3 (space group C2 / m). The positive electrode active material may contain, for example, a solid solution of LiMO2 and Li2MO3 (Li2MO3-LiMO2), etc.

[0092] 〈Transition metal oxide: space group Fd-3m〉 The transition metal oxide may contain, for example, a crystal structure belonging to the space group Fd-3m, etc. The transition metal oxide may be represented, for example, by the following formula (1-5). LiMn 2-x M x O4…(1-5) In the formula, the relationship of 0≦x≦2 is satisfied. M may contain, for example, at least one selected from the group consisting of Ni, Fe, and Zn.

[0093] LiM2O4 (space group Fd-3m) may contain, for example, at least one selected from the group consisting of LiMn2O4 and LiMn 1.5 Ni 0.5 O4. The positive electrode active material may contain, for example, a mixture of LiMO2 (space group R-3m) and LiM2O4 (space group Fd-3m). The mixing ratio (mass ratio) of LiMO2 (space group R-3m) and LiM2O4 (space group Fd-3m) may be, for example, "LiMO2 / LiM2O4 = 9 / 1 to 9 / 1", "LiMO2 / LiM2O4 = 9 / 1 to 5 / 5", or "LiMO2 / LiM2O4 = 9 / 1 to 7 / 3".

[0094] 〈Polyanion compound〉 The polyanion compound may contain, for example, phosphates (such as LiFePO4, etc.), silicates, borates, etc. The polyanion compound may be represented, for example, by the following formulas (1-6) to (1-9).

[0095] LiMPO4…(1-6) Li 2-xMPO4F …(1-7) Li2MSiO4…(1-8) LiMBO3…(1-9) In the above formulas (1-6) to (1-9), M may contain at least one selected from the group consisting of, for example, Fe, Mn, and Co. In the above formula (1-7), for example, the relationship of 0 ≦ x ≦ 2 may be satisfied.

[0096] The positive electrode active material may contain, for example, a mixture of LiMO2 (space group R-3m) and a polyanion compound. The mixing ratio (mass ratio) of LiMO2 (space group R-3m) and the polyanion compound may be, for example, "LiMO2 / polyanion compound = 9 / 1 to 9 / 1", "LiMO2 / polyanion compound = 9 / 1 to 5 / 5", or "LiMO2 / polyanion compound = 9 / 1 to 7 / 3".

[0097] 〈Dopant〉 A dopant may be added to the positive electrode active material. The dopant may be diffused throughout the particles or locally distributed. For example, the dopant may be unevenly distributed on the particle surface. The dopant may be a substitutional solid solution atom or an interstitial solid solution atom. The addition amount of the dopant (mole fraction with respect to the entire positive electrode active material) may be, for example, 0.01 to 5%, 0.1 to 3%, or 0.1 to 1%. One type of dopant may be added, or two or more types of dopants may be added. Two or more types of dopants may form a complex.

[0098] The dopant may contain at least one selected from the group consisting of, for example, B, C, N, halogen, Si, Na, Mg, Al, Mn, Co, Cr, Sc, Ti, V, Cu, Zn, Ga, Ge, Se, Sr, Y, Zr, Nb, Mo, In, Pb, Bi, Sb, Sn, W, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and actinoid.

[0099] For example, a composition of "Zr, Mg, W, Sm", a composition of "Ti, Mn, Nb, Si, Mo", or a composition of "Er, Mg" may be added to the NCA.

[0100] For example, Ti may be added to the NCM. For example, a composition of "Zr, W", a composition of "Si, W", or a composition of "Zr, W, Al, Ti, Co" may be added to the NCM.

[0101] 〈Surface Coating〉 The positive electrode active material layer 21 may contain composite particles. The composite particles include core particles and a coating layer. The core particles contain a positive electrode active material. The coating layer covers at least a part of the surface of the core particles. The coating layer may have a thickness of, for example, 1 to 3000 nm, 5 to 2000 nm, 10 to 1000 nm, 10 to 100 nm, or 10 to 50 nm. The thickness of the coating layer can be measured, for example, in an SEM (Scanning Electron Microscope) image of the particle cross-section. That is, a sample is prepared by embedding the composite particles in a resin material. The sample is subjected to cross-section processing by an ion milling apparatus. For example, an ion milling apparatus "Product name: ArBlade (registered trademark) 5000" (or an equivalent product) manufactured by Hitachi High-Technologies Corporation may be used. The cross-section of the sample is observed by SEM. For example, an SEM apparatus "Product name: SU8030" (or an equivalent product) manufactured by Hitachi High-Technologies Corporation may be used. For 10 composite particles, the thickness of the coating layer is measured in 20 fields of view each. The arithmetic mean of the thicknesses at a total of 200 locations is adopted.

[0102] The ratio of the portion of the surface of the core particles covered by the coating layer is also referred to as the "coating rate". The coating rate may be, for example, 1% or more, 10% or more, 30% or more, 50% or more, or 70% or more. The coating rate may be, for example, 100% or less, 90% or less, or 80% or less.

[0103] The coverage rate can be measured, for example, by XPS (X-ray Photoelectron Spectroscopy). For example, an XPS apparatus "Product name: PHI X-tool" (or an equivalent product) manufactured by ULVAC-PHI, Inc. may be used. A sample powder composed of composite particles is set in the XPS. Narrow scan analysis is performed. The measurement data is processed by analysis software. For example, analysis software "Product name: MulTiPak" (or an equivalent product) manufactured by ULVAC-PHI, Inc. may be used. By analyzing the measurement data, a plurality of types of elements are detected. From the area of each peak, the ratio of each detected element is obtained. The coverage rate is obtained by the following formula (1-10).

[0104] θ={I1 / (I0+I1)}×100 …(1-10) θ: Coverage rate [%] I0: Ratio of the element derived from the core particle I1: Ratio of the element derived from the coating layer For example, when the core particle contains NCM, I0 indicates the total element ratio of "Ni, Co, Mn". For example, when the core particle contains NCA, I0 indicates the total element ratio of "Ni, Co, Al". For example, when the coating layer contains P and B, I1 indicates the total element ratio of "P, B".

[0105] The coating layer may contain any component. The coating layer may contain, for example, a single substance, an organic substance, an inorganic acid salt, an organic acid salt, a hydroxide, an oxide, a carbide, a nitride, a sulfide, a halide, etc. The coating layer may contain, for example, B, Al, W, Zr, Ti, Co, F, a lithium compound (for example, Li2CO3, LiHCO3, LiOH, Li2O, etc.), tungsten oxide (for example, WO3, etc.), titanium oxide (for example, TiO2, etc.), zirconium oxide (for example, ZrO2, etc.), boron oxide, boron phosphate (for example, BPO4, etc.), aluminum oxide (for example, Al2O3, etc.), boehmite, aluminum hydroxide, phosphate [for example, Li3PO 4、(NH4)3PO4, AlPO4, etc.), borates (e.g., Li2B4O7, LiBO3, etc.), polyacrylates (Li salt, Na salt, NH4 salt, etc.), acetates (e.g., Li salt, etc.), CMC (CMC-Na, CMC-Li, CMC-NH4, etc.), LiNbO 3、 It may contain at least one selected from the group consisting of Li2TiO3 and Li-containing halides (e.g., LiAlCl4, LiTiAlF6, LiYBr6, LiYCl6, etc.).

[0106] 〈Hollow particles / Solid particles〉 The hollow particles and solid particles are secondary particles (aggregates of primary particles). In the cross-sectional image of the "hollow particles", the ratio of the area of the cavity in the central part is 30% or more of the cross-sectional area of the entire particle. The ratio of the cavity in the hollow particles may be, for example, 40% or more, 50% or more, or 60% or more. In the cross-sectional image of the "solid particles", the ratio of the area of the cavity in the central part is less than 30% of the cross-sectional area of the entire particle. The ratio of the cavity in the solid particles may be, for example, 20% or less, 10% or less, or 5% or less. The positive electrode active material may be hollow particles or solid particles. A mixture of hollow particles and solid particles may be used. The mixing ratio (mass ratio) of hollow particles and solid particles may be, for example, "hollow particles / solid particles = 1 / 9 to 9 / 1", "hollow particles / solid particles = 2 / 8 to 8 / 2", "hollow particles / solid particles = 3 / 7 to 7 / 3", or "hollow particles / solid particles = 4 / 6 to 6 / 4".

[0107] 〈Large particles / Small particles〉 The positive electrode active material may have, for example, a unimodal particle size distribution (number basis). The positive electrode active material may have, for example, a multimodal particle size distribution. The positive electrode active material may have, for example, a bimodal particle size distribution. That is, the positive electrode active material may contain large particles and small particles. When the particle size distribution is bimodal, the particle diameter corresponding to the peak top with the larger particle diameter is regarded as the particle diameter of the large particles (d L ). The particle diameter corresponding to the peak top with the smaller particle diameter is regarded as the particle diameter of the small particles (d S ). The particle size ratio (d L / dS ) may be, for example, 2 to 10, 2 to 5, or 2 to 4. d L may be, for example, 8 to 20 μm, or 8 to 15 μm. d S may be, for example, 1 to 10 μm, or 1 to 5 μm.

[0108] For example, peak separation processing may be performed on the particle size distribution by waveform analysis software. The peak area (S L ) derived from large particles and the peak area (S S ) derived from small particles, the ratio of them may be, for example, "S L / S S = 1 / 9 to 9 / 1", "S L / S S = 5 / 5 to 9 / 1", or "S L / S S = 7 / 3 to 9 / 1".

[0109] The particle size distribution based on the number is measured by the microscopic method. A plurality of cross-sectional samples are taken from the positive electrode active material layer. The cross-sectional sample may include, for example, a cross-section perpendicular to the surface of the positive electrode active material layer. For example, the observation target surface is cleaned by ion milling or the like. The cross-sectional sample is observed by SEM. The observation magnification is adjusted so that 10 to 100 particles are accommodated in the observation field of view. The Feret diameter of all the particles in the image is measured. The "Feret diameter" indicates the distance between the two farthest points on the contour line of the particle. By observing a plurality of cross-sectional samples, a total of more than 1000 Feret diameters are obtained. From the more than 1000 Feret diameters, the particle size distribution based on the number is created.

[0110] A bimodal particle size distribution can be formed by mixing two types of particles. The two types of particles have different particle size distributions from each other. For example, the two types of particles may have different D50 values. For example, the large particles may have a D50 of 8 to 20 μm, or 8 to 15 μm. For example, the small particles may have a D50 of 1 to 10 μm, or 1 to 5 μm. The ratio of the D50 of the large particles to the D50 of the small particles may be, for example, 2 to 10, 2 to 5, or 2 to 4. The mixing ratio (mass ratio) of the large particles to the small particles may be, for example, "large particles / small particles = 1 / 9 to 9 / 1", "large particles / small particles = 5 / 5 to 9 / 1", or "large particles / small particles = 7 / 3 to 9 / 1".

[0111] Note that the large particles and the small particles may have the same composition or different compositions from each other. For example, the large particles may be NCA and the small particles may be NCM. For example, the large particles may be NCM(0.6≦x) and the small particles may be NCM(x<0.6). The negative electrode active material (described later) may also contain large particles and small particles in the same manner as the positive electrode active material.

[0112] <Negative electrode active material layer> The negative electrode active material layer 22 may have a thickness of, for example, 10 to 1000 μm, 50 to 500 μm, or 100 to 300 μm. The negative electrode active material layer 22 contains a negative electrode active material. The negative electrode active material layer 22 may further contain, for example, a conductive material and a binder.

[0113] <Conductive material> The conductive material can form an electron conduction path in the negative electrode active material layer 22. The compounding amount of the conductive material may be, for example, 0.1 to 10 parts by mass with respect to 100 parts by mass of the negative electrode active material. The conductive material may contain any component. The conductive material may contain, for example, at least one selected from the group consisting of AB, Ketjen black (registered trademark), VGCF, CNT, and GF. The CNT may contain at least one selected from the group consisting of single-walled CNT (SWCNT) and multi-walled CNT (MWCNT).

[0114] "Binder" The binder can fix the negative electrode active material layer 22 to the electrode current collector 10. The blending amount of the binder may be, for example, 0.1 to 10 parts by mass with respect to 100 parts by mass of the negative electrode active material. The binder may contain any component. The binder may contain, for example, at least one selected from the group consisting of styrene butadiene rubber (SBR), acrylate butadiene rubber (ABR), sodium alginate, carboxymethyl cellulose (CMC-H, CMC-Na, CMC-Li, CMC-NH4, etc.), polyacrylic acid (PAA-H, PAA-Na, PAA-Li, etc.), polyacrylonitrile (PAN), PVdF, PTFE, acrylic resin, methacrylic resin, PVP, PVA, and derivatives thereof. For example, the description of "CMC-Na" indicates the Na salt of CMC. For example, the description of "CMC-H" indicates the acid type CMC. The same applies to "PAA-Na" etc.

[0115] "Other Components" The negative electrode active material layer 22 may further contain, for example, an inorganic filler, an organic filler, a solid electrolyte, a surface modifier, a dispersant, a lubricant, a flame retardant, a protective agent, a flux, a coupling agent, an adsorbent, etc. The negative electrode active material layer 22 may contain, for example, a layered silicate (smectite, montmorillonite, bentonite, hectorite, etc.), an inorganic filler (solid alumina, hollow silica, boehmite, etc.), a polysiloxane compound, etc.

[0116] "Negative Electrode Active Material" The negative electrode active material may be, for example, particulate or sheet-like. The negative electrode active material may have a D50 of, for example, 1 to 30 μm, 10 to 20 μm, or 1 to 10 μm.

[0117] 〈Carbon-based Active Material〉 The negative electrode active material may contain, for example, a carbon-based active material. The carbon-based active material may contain, for example, at least one selected from the group consisting of graphite, soft carbon, and hard carbon. "Graphite" is a general term for natural graphite and artificial graphite. Graphite may be a mixture of natural graphite and artificial graphite. The mixing ratio (mass ratio) may be, for example, "natural graphite / artificial graphite = 1 / 9 to 9 / 1", "natural graphite / artificial graphite = 2 / 8 to 8 / 2", or "natural graphite / artificial graphite = 3 / 7 to 7 / 3".

[0118] Graphite may contain a dopant. The dopant may contain, for example, at least one selected from the group consisting of B, N, P, Li, and Ca. The addition amount may be, for example, 0.01 to 5%, 0.1 to 3%, or 0.1 to 1% in molar fraction.

[0119] The surface of the graphite may be coated with, for example, amorphous carbon. The surface of the graphite may be coated with, for example, a different material. The different material may contain, for example, at least one selected from the group consisting of P, W, Al, and O. The different material may contain, for example, at least one selected from the group consisting of Al(OH)3, AlOOH, Al2O3, WO3, Li2CO3, LiHCO 3、 and Li3PO4.

[0120] 〈Alloy-based active material〉 The negative electrode active material may contain, for example, an alloy-based active material. The negative electrode active material may contain, for example, at least one selected from the group consisting of Si, Li silicate, SiO, Si-based alloy, Sn, SnO, and Sn-based alloy.

[0121] SiO may be represented by, for example, the following formula (2-1).

[0122] SiO x …(2-1) In the formula, the relationship of 0 < x < 2 is satisfied.

[0123] In the above formula (2-1), x may satisfy a relationship such as 0.5 ≦ x ≦ 1.5, or 0.8 ≦ x ≦ 1.2.

[0124] The Li silicate may contain, for example, at least one selected from the group consisting of Li4SiO4, Li2SiO3, Li2Si2O5, and Li8SiO6. The negative electrode active material may contain, for example, a mixture of Si and Li silicate. The mixing ratio (mass ratio) may be, for example, "Si / Li silicate = 1 / 9 to 9 / 1", "Si / Li silicate = 2 / 8 to 8 / 2", "Si / Li silicate = 3 / 7 to 7 / 3", or "Si / Li silicate = 4 / 6 to 6 / 4".

[0125] The alloy-based active material (Si, SiO, etc.) may contain an additive. The additive may be, for example, a substitutional solid solution atom or an interstitial solid solution atom. The additive may be an adherent adhering to the surface of the alloy-based active material. The adherent may be, for example, a simple substance, an oxide, a carbide, a nitride, a halide, etc. The addition amount may be, in terms of mole fraction, for example, 0.01 to 5%, 0.1 to 3%, or 0.1 to 1%. The additive may contain, for example, at least one selected from the group consisting of Li, Na, K, Rb, Be, Mg, Ca, Sr, Fe, Ba, B, Al, Ga, In, C, Ge, Sn, Pb, N, P, As, Y, Sb, and S. That is, Mg and Na may be doped into SiO. For example, Mg silicate, Na silicate, etc. may be formed. For example, boron oxide (e.g., B2O3, etc.), yttrium oxide (e.g., Y2O3, etc.), etc. may be added to SiO.

[0126] 〈Si-C composite material〉 The negative electrode active material may contain, for example, a composite material of a carbon-based active material (graphite, etc.) and an alloy-based active material (Si, etc.). The composite material containing Si and carbon may also be referred to as a "Si-C composite material". For example, Si fine particles may be dispersed in carbon particles. For example, Si fine particles may be dispersed in graphite particles. For example, Li silicate particles may be coated with a carbon material (amorphous carbon, etc.).

[0127] <Other active materials> The negative electrode active material may contain at least one selected from the group consisting of, for example, Li metal, Li-based alloys, and Li4Ti5O 12 and the like. The negative electrode active material may contain, for example, a Li foil or the like.

[0128] <Separator> The separator 30 can separate the positive electrode active material layer 21 from the negative electrode active material layer 22. The separator 30 has electrical insulation. The separator 30 may contain at least one selected from the group consisting of, for example, a resin film, an inorganic particle layer, and an organic particle layer. The separator 30 may contain, for example, a resin film and an inorganic particle layer.

[0129] 《Resin film》 The resin film is porous. The resin film may contain, for example, a microporous membrane, a nonwoven fabric, or the like. The resin film contains a resin skeleton. The resin skeleton may be continuously networked, for example. Pores are formed in the gaps of the resin skeleton. The resin film can permeate a liquid electrolyte. The resin film may have an average pore diameter of 1 μm or less, for example. The resin film may have an average pore diameter of 0.01 to 1 μm, or 0.1 to 0.5 μm, for example. The "average pore diameter" can be measured by the mercury intrusion method. The resin film may have a Gurley value of 50 to 250 s / 100 cm 3 and the like. The "Gurley value" can be measured by the Gurley test method.

[0130] The resin film may contain at least one selected from the group consisting of, for example, olefin resins, urethane resins, polyamide resins, cellulose resins, polyether resins, acrylic resins, and polyester resins. The resin film may contain at least one selected from the group consisting of, for example, PE, PP, PA, PAI, PI, aromatic polyamide (aramid), PPE, and derivatives thereof. The resin film can be formed, for example, by a stretching method, a phase separation method, etc. The resin film may have a thickness of, for example, 5 to 50 μm, or 10 to 25 μm.

[0131] The resin film may have, for example, a single-layer structure. The resin film may be composed of, for example, a PE layer. The skeleton of the PE layer is formed by PE. The PE layer can have a shutdown function. The resin film may have, for example, a multilayer structure. The resin film may include, for example, a PP layer and a PE layer. The skeleton of the PP layer is formed by PP. The resin film may have, for example, a three-layer structure. The resin film may be formed, for example, by laminating a PP layer, a PE layer, and a PP layer in this order. The thickness of the PE layer may be, for example, 5 to 20 μm. The thickness of the PP layer may be, for example, 3 to 10 μm.

[0132] 《Inorganic Particle Layer》 The inorganic particle layer may be formed on the surface of the resin film. The inorganic particle layer may be formed on only one side of the resin film, or on both the front and back sides. The inorganic particle layer may be formed on the surface facing the positive electrode active material layer 21, or on the surface facing the negative electrode active material layer 22. Note that the inorganic particle layer may be formed on the surface of the positive electrode active material layer 21, or on the surface of the negative electrode active material layer 22.

[0133] The inorganic particle layer is porous. The inorganic particle layer contains inorganic particles. The inorganic particles may also be referred to as "inorganic fillers". Pores are formed in the gaps between the inorganic particles. The inorganic particle layer may have a thickness of, for example, 0.5 to 10 μm, or 1 to 5 μm. The inorganic particles may contain, for example, a heat-resistant material. The inorganic particle layer containing a heat-resistant material is also referred to as "HRL (Heat Resistance Layer)". The inorganic particles may contain at least one selected from the group consisting of boehmite, alumina, zirconia, titania, magnesia, silica, etc. The inorganic particles can have any shape. The inorganic particles may be, for example, spherical, rod-shaped, plate-shaped, fibrous, etc. The inorganic particles may have a D50 of, for example, 0.1 to 10 μm, or 0.5 to 3 μm. The inorganic particle layer may further contain a binder. The binder may contain at least one selected from the group consisting of acrylic resins, polyamide resins, fluorine resins, aromatic polyether resins, and liquid crystal polyester resins, etc.

[0134] 《Organic Particle Layer》 The separator 30 may contain, for example, an organic particle layer. The separator 30 may contain, for example, an organic particle layer instead of a resin film. The separator 30 may contain, for example, an organic particle layer instead of an inorganic particle layer. The separator 30 may contain both a resin film and an organic particle layer. The separator 30 may contain both an inorganic particle layer and an organic particle layer. The separator 30 may contain a resin film, an inorganic particle layer, and an organic particle layer.

[0135] The organic particle layer may have a thickness of, for example, 0.1 to 50 μm, 0.5 to 20 μm, 0.5 to 10 μm, or 1 to 5 μm. The organic particle layer contains organic particles. The organic particles may also be referred to as "organic fillers". The organic particles may contain a heat-resistant material. The organic particles may contain at least one selected from the group consisting of, for example, PE, PP, PTFE, PI, PAI, PA, and aramid. The organic particles may be, for example, spherical, rod-shaped, plate-shaped, fibrous, etc. The organic particles may have a D50 of, for example, 0.1 to 10 μm, or 0.5 to 3 μm.

[0136] The separator 30 may contain, for example, a mixed layer. The mixed layer contains both inorganic particles and organic particles.

[0137] <Liquid electrolyte> The bipolar battery 100 may contain a liquid electrolyte. The liquid electrolyte is a Li-ion conductor. The liquid electrolyte may contain, for example, an electrolytic solution. The electrolytic solution contains a solvent and a solute.

[0138] 《Solute》 The concentration of the solute may be, for example, 0.5 to 1 mol / L, 1 to 1.5 mol / L, 1.5 to 2 mol / L, 2 to 2.5 mol / L, or 2.5 to 3 mol / L. The solute contains a supporting salt (Li salt). The solute may contain, for example, an inorganic acid salt, an imide salt, an oxalato complex, a halide, etc. The solute may contain at least one selected from the group consisting of, for example, LiPF6, LiBF4, LiClO4, LiAsF6, LiSbF6, LiN(SO2F)2 "LiFSI", LiN(SO2CF3)2 "LiTFSI", LiB(C2O4)2 "LiBOB", LiBF2(C2O4) "LiDFOB", LiPF2(C2O4)2 "LiDFOP", LiPO2F2, FSO3Li, LiI, LiBr, and derivatives thereof.

[0139] 《Carbonate solvent》 The electrolyte may contain, for example, a carbonate solvent (carbonate ester solvent). The solvent may contain, for example, cyclic carbonates, chain carbonates, fluorinated carbonates, etc. The solvent may contain at least one selected from the group consisting of, for example, ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), monofluoroethylene carbonate (FEC), difluoroethylene carbonate, 4,4-difluoroethylene carbonate, trifluoroethylene carbonate, perfluoroethylene carbonate, fluoropropylene carbonate, difluoropropylene carbonate, and derivatives thereof.

[0140] The solvent may contain cyclic carbonates (such as EC, PC, FEC, etc.) and chain carbonates (such as EMC, DMC, DEC, etc.). The mixing ratio (volume ratio) of the cyclic carbonate and the chain carbonate may be, for example, "cyclic carbonate / chain carbonate = 1 / 9 to 4 / 6", "cyclic carbonate / chain carbonate = 2 / 8 to 3 / 7", or "cyclic carbonate / chain carbonate = 3 / 7 to 4 / 6".

[0141] The solvent may contain cyclic carbonates (such as EC, PC, etc.) and fluorinated cyclic carbonates (such as FEC, etc.). The mixing ratio (volume ratio) of the cyclic carbonate and the fluorinated cyclic carbonate may be, for example, "cyclic carbonate / fluorinated cyclic carbonate = 99 / 1 to 90 / 10", "cyclic carbonate / fluorinated cyclic carbonate = 9 / 1 to 1 / 9", "cyclic carbonate / fluorinated cyclic carbonate = 9 / 1 to 7 / 3", or "cyclic carbonate / fluorinated cyclic carbonate = 3 / 7 to 1 / 9".

[0142] The solvent may contain, for example, EC, FEC, EMC, DMC, and DEC. The volume ratio of each component may satisfy, for example, the relationship represented by the following formula (3-1).

[0143] V EC +V FEC +V EMC +V DMC +V DEC =10 …(3-1) In the formula, V EC , V FEC , V EMC , V DMC , V DEC represents the volume ratios of EC, FEC, EMC, DMC, and DEC, respectively. 1 ≦ V EC ≦ 4, 0 ≦ V FEC ≦ 3, V EC +V FEC ≦ 4, 0 ≦ V EMC ≦ 9, 0 ≦ V DMC ≦ 9, 0 ≦ V DEC ≦ 9, 6 ≦ V EMC +V DMC +V DEC ≦ 9 The relationship is satisfied.

[0144] In the above formula (3-1), For example, the relationship of 1 ≦ V EC ≦ 2, or 2 ≦ V EC ≦ 3 may be satisfied. For example, the relationship of 1 ≦ V FEC ≦ 2, or 2 ≦ V FEC ≦ 4 may be satisfied. For example, the relationship of 3 ≦ V EMC ≦ 4, or 6 ≦ V EMC ≦ 8 may be satisfied. For example, the relationship of 3 ≦ V DMC ≦ 4, or 6 ≦ V DMC ≦ 8 may be satisfied. For example, the relationship of 3 ≦ V DEC ≦ 4, or 6 ≦ V DEC ≦ 8 may be satisfied.

[0145] The solvent may have a composition such as "EC / EMC = 3 / 7", "EC / DMC = 3 / 7", "EC / FEC / DEC = 1 / 2 / 7", "EC / DMC / EMC = 3 / 4 / 3", "EC / DMC / EMC = 3 / 3 / 4", "EC / FEC / DMC / EMC = 2 / 1 / 4 / 3", "EC / FEC / DMC / EMC = 1 / 2 / 4 / 3", "EC / FEC / DMC / EMC = 2 / 1 / 3 / 4", "EC / FEC / DMC / EMC = 1 / 2 / 3 / 4", etc. by volume ratio.

[0146] 《Ether-based solvent》 The electrolyte may contain an ether-based solvent. The electrolyte may contain, for example, at least one selected from the group consisting of tetrahydrofuran (THF), 1,4-dioxane (DOX), 1,3-dioxolane (DOL), 1,2-dimethoxyethane (DME), 1,2-diethoxyethane (DEE), hydrofluoroether (HFE), ethyl glyme, triglyme, tetraglyme, and derivatives thereof.

[0147] 《Additive》 The electrolyte may contain any additive. The addition amount (mass fraction relative to the entire electrolyte) may be, for example, 0.01 to 5%, 0.05 to 3%, or 0.1 to 1%. The additive may contain, for example, an SEI (Solid Electrolyte Interphase) formation promoter, an SEI formation inhibitor, a gas generator, an overcharge prevention agent, a flame retardant, an antioxidant, an electrode protector, a surfactant, etc.

[0148] Additives include, for example, vinylene carbonate (VC), vinyl ethylene carbonate (VEC), 1,3 - propane sultone (PS), tert - amyl benzene, 1,4 - di - tert - butyl benzene, biphenyl (BP), cyclohexyl benzene (CHB), ethylene sulfite (ES), propane sultone (PS), ethylene sulfate (DTD), γ - butyrolactone, phosphazene compounds, carboxylic acid esters [e.g., methyl formate (MF), methyl acetate (MA), methyl propionate (MP), diethyl malonate (DEM), etc.], fluorobenzenes [e.g., monofluorobenzene (FB), 1,2 - difluorobenzene, 1,3 - difluorobenzene, 1,4 - difluorobenzene, 1,2,3 - trifluorobenzene, 1,2,4 - trifluorobenzene, 1,3,5 - trifluorobenzene, 1,2,3,4 - tetrafluorobenzene, 1,2,3,5 - tetrafluorobenzene, 1,2,4,5 - tetrafluorobenzene, pentafluorobenzene, hexafluorobenzene, etc.], fluorotoluenes (e.g., 2 - fluorotoluene, 3 - fluorotoluene, 4 - fluorotoluene, 2,3 - difluorotoluene, 2,4 - difluorotoluene, 2,5 - difluorotoluene, 2,6 - difluorotoluene, 3,4-difluorotoluene, octafluorotoluene, etc.), benzotrifluoride (e.g., benzotrifluoride, 2-fluorobenzotrifluoride, 3-fluorobenzotrifluoride, 4-fluorobenzotrifluoride, 2-methylbenzotrifluoride, 3-methylbenzotrifluoride, 4-methylbenzotrifluoride, etc.), fluoroxylene (e.g., 3-fluoro-o-xylene, 4-fluoro-o-xylene, 2-fluoro-m-xylene, 5-fluoro-m-xylene, etc.), sulfur-containing heterocyclic compounds (e.g., benzothiazole, 2-methylbenzothiazole, tetrathiafulvalene, etc.), nitrile compounds (e.g., adiponitrile, succinonitrile, etc.), phosphate esters (e.g., trimethyl phosphate, triethyl phosphate, etc.), carboxylic anhydrides (e.g., acetic anhydride, propionic anhydride, oxalic anhydride, succinic anhydride, maleic anhydride, phthalic anhydride, benzoic anhydride, etc.), alcohols (e.g., methanol, ethanol, n-propyl alcohol, ethylene glycol, diethylene glycol monomethyl ether, etc.), and may contain at least one selected from the group consisting of derivatives thereof.,

[0149] The components described above as solutes and solvents may be used as trace components (additives). Additives may include, for example, at least one selected from the group consisting of LiBF4, LiFSI, LiTFSI, LiBOB, LiDFOB, LiDFOP, LiPO2F2, FSO3Li, LiI, LiBr, HFE, DOX, PC, FEC, and derivatives thereof.

[0150] 《Ionic Liquid》 The liquid electrolyte may contain an ionic liquid. The liquid electrolyte may include, for example, at least one selected from the group consisting of sulfonium salts, ammonium salts, pyridinium salts, piperidinium salts, pyrrolidinium salts, morpholinium salts, phosphonium salts, imidazolium salts, and derivatives thereof.

[0151] <Gel Electrolyte> The bipolar battery 100 may contain a gel electrolyte. The gel electrolyte may contain a liquid electrolyte and a polymer material. The polymer material may form a polymer matrix. The polymer material may contain, for example, at least one selected from the group consisting of PVdF, PVdF-HFP, PAN, PVdF-PAN, polyethylene oxide (PEO), polyethylene glycol (PEG), and derivatives thereof.

[0152] <Battery configuration> Figure 5 is Table 2 showing the first battery configuration. Figure 6 is Table 3 showing the second battery configuration. Figure 7 is Table 4 showing the third battery configuration. In each table, when multiple types of materials are described in a cell, the description includes each material alone and combinations thereof. For example, when the materials "α, β, γ" are described in a cell, the description indicates "at least one selected from the group consisting of α, β, and γ". Any elements may be extracted from the first to third battery configurations and combined arbitrarily. The bipolar battery 100 may include, for example, the first to third battery configurations.

[0153] <<All-solid-state battery>> Figure 8 is a conceptual diagram showing the all-solid-state battery in this embodiment. The electrode current collector 10 may be, for example, for an all-solid-state battery. The all-solid-state battery 200 may be, for example, a bipolar battery or a monopolar battery. The all-solid-state battery 200 in Figure 8 is a monopolar battery. In a monopolar battery, the positive electrode active material layer 21 may be disposed on both the front and back surfaces of the electrode current collector 10. The negative electrode active material layer 22 may be disposed on both the front and back surfaces of the electrode current collector 10. The electrode active material layer may be disposed on only one side of the electrode current collector 10.

[0154] <Solid electrolyte> In all-solid-state battery 200, the electrode active material layer contains a solid electrolyte in addition to the electrode active material, the conductive material, and the binder. The solid electrolyte can form an ion conduction path within the electrode active material layer. The solid electrolyte may be, for example, particulate. The solid electrolyte may have a D50 of, for example, 0.1 to 3 μm. The D50 of the solid electrolyte may be, for example, 1 μm or less, or 0.5 μm or less. The blending amount of the solid electrolyte may be, for example, 1 to 200 parts by volume, 50 to 150 parts by volume, or 50 to 100 parts by volume with respect to 100 parts by volume of the electrode active material.

[0155] 《Sulfide Solid Electrolyte》 The electrode active material layer may contain, for example, a sulfide solid electrolyte. The sulfide solid electrolyte may be, for example, glass ceramics or argyrodite. The sulfide solid electrolyte may contain at least one selected from the group consisting of, for example, LiI-LiBr-Li3PS4, Li2S-SiS2, LiI-Li2S-SiS2, LiI-Li2S-P2S5, LiI-Li2O-Li2S-P2S5, LiI-Li2S-P2O5, LiI-Li3PO4-P2S5, Li2S-GeS2-P2S5, Li2S-P2S5, Li 10 GeP2S 12 、Li4P2S6, Li7P3S 11 、Li3PS4, Li7PS6, and at least one selected from the group consisting of Li6PS5X (X = Cl, Br, I).

[0156] For example, "LiI-LiBr-Li3PS4" indicates a sulfide solid electrolyte formed by mixing LiI, LiBr, and Li3PS4 in an arbitrary molar ratio. For example, the sulfide solid electrolyte may be produced by a mechanochemical method. "Li2S-P2S5" contains Li3PS4. Li3PS4 can be produced, for example, by mixing Li2S and P2S5 at "Li2S / P2S5 = 75 / 25 (molar ratio)".

[0157] 《Other Solid Electrolytes》 The electrode active material layer may further contain other solid electrolytes in addition to the sulfide solid electrolyte. Hereinafter, for convenience, the sulfide solid electrolyte may also be referred to as the "first solid electrolyte", and the other solid electrolytes may also be referred to as the "second solid electrolyte". The volume ratio of the first solid electrolyte to the second solid electrolyte may be, for example, "first solid electrolyte / second solid electrolyte = 1 / 99 to 99 / 1", "first solid electrolyte / second solid electrolyte = 1 / 9 to 9 / 1", or "first solid electrolyte / second solid electrolyte = 3 / 7 to 7 / 3". The first solid electrolyte and the second solid electrolyte may be subjected to a composite treatment.

[0158] The second solid electrolyte may contain, for example, at least one selected from the group consisting of halide solid electrolytes, oxide solid electrolytes, hydride solid electrolytes, and nitride solid electrolytes.

[0159] The halide solid electrolyte may be represented by, for example, the following formula (4-1). Li 6-na M a X6…(4-1) In the formula, n represents the oxidation number of M. M may contain, for example, an atom having an oxidation number of +3. M may contain, for example, an atom having an oxidation number of +4. M may contain, for example, at least one selected from the group consisting of Y, Al, Ti, Zr, Ca, and Mg. a may satisfy the relationship 0 < a < 2. X may contain, for example, at least one selected from the group consisting of F, Cl, Br, and I.

[0160] The halide solid electrolyte may be represented by, for example, the following formula (4-2). Li 3-a Ti a Al 1-a F6…(4-2) In the formula, a may satisfy, for example, the relationship 0 ≤ a ≤ 0.1, 0.1 ≤ a ≤ 0.2, 0.2 ≤ a ≤ 0.3, 0.3 ≤ a ≤ 0.4, 0.4 ≤ a ≤ 0.5, 0.5 ≤ a ≤ 0.6, 0.6 ≤ a ≤ 0.7, 0.7 ≤ a ≤ 0.8, 0.8 ≤ a ≤ 0.9, or 0.9 ≤ a ≤ 1.

[0161] The halide solid electrolyte may be represented, for example, by the following formula (4-3). Li3YCl a Br b I 6-a-b …(4-3) In the formula, the relationship of 0 ≦ a + b ≦ 6 is satisfied. a may satisfy, for example, the relationship of 0 ≦ a ≦ 1, 1 ≦ a ≦ 2, 2 ≦ a ≦ 3, 3 ≦ a ≦ 4, 4 ≦ a ≦ 5, or 5 ≦ a ≦ 6. b may satisfy, for example, the relationship of 0 ≦ b ≦ 1, 1 ≦ b ≦ 2, 2 ≦ b ≦ 3, 3 ≦ b ≦ 4, 4 ≦ b ≦ 5, or 5 ≦ b ≦ 6.

[0162] The oxide solid electrolyte may contain, for example, at least one selected from the group consisting of LiNbO3, Li 1.5 Al 0.5 Ge 1.5 (PO4)3, La 2 / 3-x Li 3x TiO3, and Li7La3Zr2O 12 and may contain at least one selected from the group consisting of LiBH4 and the like. The hydride solid electrolyte may contain, for example, LiBH4 or the like. The nitride solid electrolyte may contain, for example, Li3N, Li3BN2 or the like.

[0163] <Solid electrolyte layer> The all-solid-state battery 200 includes a solid electrolyte layer 40. The solid electrolyte layer 40 corresponds to a separator. The solid electrolyte layer 40 is interposed between the positive electrode active material layer 21 and the negative electrode active material layer 22. The solid electrolyte layer 40 separates the positive electrode active material layer 21 from the negative electrode active material layer 22. The solid electrolyte layer 40 may have a thickness of, for example, 1 to 50 μm.

[0164] The solid electrolyte layer 40 contains a solid electrolyte. The solid electrolyte layer 40 may further contain, for example, a binder. The solid electrolyte may be the same or different between the solid electrolyte layer 40 and the electrode active material layer. The solid electrolyte layer 40 may contain at least one selected from the group consisting of, for example, a sulfide solid electrolyte, a halide solid electrolyte, an oxide solid electrolyte, a hydride solid electrolyte, and a nitride solid electrolyte. The blending amount of the binder may be, for example, 0.1 to 10 parts by mass with respect to 100 parts by mass of the solid electrolyte. The binder may be the same or different between the solid electrolyte layer 40 and the electrode active material layer.

[0165] The solid electrolyte layer 40 may have a single-layer structure or a multilayer structure. The solid electrolyte layer 40 may have, for example, a 2- to 5-layer structure. For example, in each layer, the solid electrolytes may be different from each other. For example, in each layer, the densities may be different from each other. For example, in each layer, the particle size (e.g., D50, etc.) of the solid electrolyte may be different from each other.

[0166] For example, the solid electrolyte layer 40 may include a first layer 41 and a second layer 42. The first layer 41 is in contact with the positive electrode active material layer 21. The second layer 42 is in contact with the negative electrode active material layer 22. The ratio of the thickness of the first layer 41 to the second layer 42 may be, for example, "first layer / second layer = 1 / 9 to 9 / 1", or "first layer / second layer = 3 / 7 to 7 / 3".

[0167] The first layer 41 may have a composition different from that of the second layer 42. For example, the first layer 41 may contain a sulfide solid electrolyte, and the second layer 42 may contain a halide solid electrolyte. For example, the first layer 41 may contain a halide solid electrolyte, and the second layer 42 may contain a sulfide solid electrolyte. The first layer 41 may contain both a sulfide solid electrolyte and a halide solid electrolyte. The second layer 42 may contain both a sulfide solid electrolyte and a halide solid electrolyte. The volume ratio of the halide solid electrolyte to the sulfide solid electrolyte in the first layer 41 (the first volume ratio) may be greater than the volume ratio of the halide solid electrolyte to the sulfide solid electrolyte in the second layer 42 (the second volume ratio). The first volume ratio may be smaller than the second volume ratio.

Example

[0168] <<Manufacture of Electrode Current Collector>> The electrode current collectors according to Nos. 1 to 5 were manufactured as follows.

[0169] <No.1> In a twin-screw extrusion kneader, the resin material (LLDPE) and the conductive particles (AB) were melt-kneaded. The kneading temperature was 200 °C. Thereby, a resin composition was formed. The blending ratio (mass ratio) was "resin material / conductive particles = 77.5 / 22.5".

[0170] In an extrusion laminator, the resin composition was heated to 320 °C, whereby a melt was formed. The melt was extruded in a film shape from a T-die, whereby a resin film was formed. The resin film and the metal foil (Al foil, thickness: 40 μm) were passed through the roll gap, whereby the resin film (conductive resin layer) was directly laminated on the metal foil. The conductive resin layer had a thickness of 10 μm.

[0171] A coating solution was formed by mixing conductive carbon particles (AB), a binder (PVdF), and a dispersion medium (NMP). In the coating solution, the mixing ratio (mass ratio) of the solid content was "conductive carbon particles / binder = 90 / 10". The solid content concentration of the coating solution was 30% by mass fraction. The coating solution was applied to the surface of the conductive resin layer by an applicator. Thereby, a first carbon particle layer was formed. The basis weight of the first carbon particle layer was 1 mg / cm 2 Thereby, an electrode current collector was manufactured.

[0172] <No.2> In a twin-screw extrusion kneader, melt kneading of a resin material (LLDPE) and conductive particles (Ni particles) was carried out. The kneading temperature was 200 °C. Thereby, a resin composition was formed. The mixing ratio (mass ratio) was "resin material / conductive particles = 90 / 10". Except for these, an electrode current collector was manufactured in the same manner as No.1.

[0173] <No.3> An electrode current collector was manufactured in the same manner as No.1 except that the first carbon particle layer was not formed.

[0174] <No.4> An electrode current collector was manufactured in the same manner as No.2 except that the first carbon particle layer was not formed.

[0175] <No.5> An electrode current collector (clad foil) was manufactured by bonding an Al foil (thickness: 40 μm) and a Cu foil (thickness: 10 μm) with a conductive adhesive. In the electrode current collector according to No.5, an adhesive layer (thickness: 3 μm) was interposed between the Al foil and the Cu foil. The adhesive layer is composed of a conductive binder.

[0176] <<Evaluation>> In coin-type cells (first cell, second cell, third cell), the electrode current collector was evaluated. The coin-type cells had a monopolar structure. The cell resistance of the coin-type cells was measured by the IV method.

[0177] Figure 9 is a conceptual diagram showing the first cell. The first cell 101 includes current collectors related to No.1 and 2. The first cell 101 includes a current collector 10, a positive electrode active material layer 21, a negative electrode active material layer 22, an Al foil 15, and a separator 30. The positive electrode active material layer 21 is disposed on the surface of the Al foil 15. The negative electrode active material layer 22 is disposed on the surface of the current collector 10 (the first carbon particle layer 13a). The members are laminated such that the positive electrode active material layer 21 and the negative electrode active material layer 22 face each other with the separator 30 interposed therebetween.

[0178] The positive electrode active material layer 21 and the negative electrode active material layer 22 can each be formed by coating, drying, and compressing a paste. The configurations of the positive electrode active material layer 21 and the negative electrode active material layer 22 are as follows.

[0179] Positive electrode active material layer 21 Areal density: 38 mg / cm 2 Density: 3.0 g / cm 3 Positive electrode active material: NCM Conductive material: AB Binder: PVdF Mixing ratio: "NCM / AB / PVdF = 95 / 2.5 / 2.5 (mass ratio)"

[0180] Negative electrode active material layer 22 Areal density: 22.6 mg / cm 2 Density: 1.2 g / cm 3 Negative electrode active material: graphite (coated with amorphous carbon) Binders: CMC, SBR Mixing ratio: "graphite / CMC / SBR = 97 / 0.7 / 2.3 (mass ratio)"

[0181] Figure 10 is a conceptual diagram showing the second cell. The second cell 102 includes current collectors related to No.3 and 4. The second cell 102 is different from the first cell 101 in that it does not include the first carbon particle layer 13a. Other configurations are the same as those of the first cell 101.

[0182] FIG. 11 is a conceptual diagram showing a third cell. The third cell 103 includes the current collector of Electrode No. 5. The third cell 103 corresponds to the one in which the conductive resin layer 12 is replaced with the Cu foil 16 in the second cell 102. Further, the third cell 103 includes an adhesive layer 17 between the Al foil 15 and the Cu foil 16.

[0183] <<Results>> FIG. 12 is Table 5 showing the evaluation results of the current collector. The battery resistance in Table 5 is a relative value. The battery resistance at No. 5 is defined as 100%.

[0184] No. 1 and 2 showed a battery resistance comparable to that of No. 5 (clad foil). No. 1 and 2 had a reduced metal amount compared to No. 5. No. 1 and 2 had a higher mass energy density than No. 5.

[0185] No. 3 and 4 had a higher battery resistance than No. 1 and 2. No. 1 and 2 included the first carbon particle layer. No. 3 and 4 did not include the first carbon particle layer. In No. 3 and 4, it is considered that the battery resistance increased because the spots of the electrode reaction were large.

[0186] Current mapping was measured by SPM in the first carbon particle layer of No. 1 and the conductive resin layer of No. 3. In No. 1, the standard deviation of the current was 0.139 nA. In No. 3, the standard deviation of the current was 1.08 nA.

Explanation of Symbols

[0187] 10 Electrode current collector, 11 Metal foil, 11a First main surface, 11b Second main surface, 12 Conductive resin layer, 13a First carbon particle layer, 13b Second carbon particle layer, 15 Al foil, 16 Cu foil, 17 Adhesive layer, 20 Bipolar electrode, 21 Positive electrode active material layer, 22 Negative electrode active material layer, 30 Separator, 40 Solid electrolyte layer, 41 First layer, 42 Second layer, 50 Power generation element, 100 Bipolar battery, 101 First cell, 102 Second cell, 103 Third cell, 200 All-solid-state battery, T1 First thickness, T2 Second thickness, T3 Third thickness.

Claims

1. A metal foil, a conductive resin layer, and a carbon particle layer are included in this order, the conductive resin layer includes a continuous phase and a dispersed phase, the continuous phase includes a resin material, the dispersed phase includes conductive particles, the conductive resin layer is impermeable to an electrolytic solution containing an organic solvent, the carbon particle layer contains 75% or more of conductive carbon particles by mass fraction, and the carbon particle layer is thinner than the conductive resin layer, an electrode current collector.

2. the metal foil is an aluminum foil, and the resin material is an olefin resin, the electrode current collector according to Claim 1.

3. the metal foil has a thickness of 20 to 40 μm, the conductive resin layer has a thickness of 5 to 20 μm, and the carbon particle layer has a thickness of 0.5 to 5 μm, the electrode current collector according to Claim 1.

4. the conductive resin layer contains 5 to 30% of the conductive particles by mass fraction and the balance of the resin material, and the carbon particle layer contains 80 to 99% of the conductive carbon particles by mass fraction and the balance of a binder, the electrode current collector according to Claim 1.

5. the conductive particles include at least one selected from the group consisting of conductive carbon particles and metal particles, the electrode current collector according to Claim 1.

6. The conductive particles include at least one selected from the group consisting of acetylene black, furnace black, graphite, vapor-grown carbon fiber, carbon nanotube, carbon nanofiber, carbon nanosphere, nickel particle, tin particle, copper particle, nickel-tin alloy particle, copper-tin alloy particle, and copper-nickel alloy particle. The electrode current collector according to claim 1.

7. On the surface of the carbon particle layer, the current mapping result measured by a scanning probe microscope has a standard deviation of 0.3 nA or less. The current mapping result is measured by an applied voltage of 10 V in a measurement region of 80 μm square. The electrode current collector according to any one of claims 1 to 6.

8. including a bipolar electrode. The bipolar electrode includes the electrode current collector according to claim 1, a positive electrode active material layer, and a negative electrode active material layer. The bipolar electrode The positive electrode active material layer The metal foil The conductive resin layer The carbon particle layer, and The negative electrode active material layer includes them in this order. A bipolar battery.

9. including the electrode current collector according to claim 1. An all-solid-state battery.

10. A method for manufacturing the electrode current collector according to claim 1, (a) forming a resin composition by mixing the resin material and the conductive particles; (b) forming the conductive resin layer by directly laminating the melt of the resin composition on the metal foil by an extrusion lamination method, and (c) forming the carbon particle layer by applying the conductive carbon particles to the conductive resin layer. includes them in this order. Method for manufacturing an electrode current collector.

Images