Battery, Battery Outer Package, and Measurement Method

Abstract

This battery is provided with: a power generation element unit which comprises a first electrode layer, a second electrode layer and a first solid electrolyte layer that is positioned between the first electrode layer and the second electrode layer; and a reference electrode unit which comprises a second solid electrolyte layer that has a first main surface which is in contact with the lateral surface of the power generation element unit and a second main surface that is on the reverse side of the first main surface, and a reference electrode that is in contact with the second main surface of the second solid electrolyte layer. With respect to this battery, the length of the first main surface is longer than the length of the lateral surface in the stacking direction of the power generation element unit.

Description

Technical Field

[0001] The present disclosure relates to a battery, an outer package for a battery, and a measurement method.

Background Art

[0002] Instead of an electrolyte containing a flammable organic solvent used in a battery such as a conventional non-aqueous electrolyte lithium ion secondary battery, a solid battery using a flame-retardant solid electrolyte has high superiority as a basic performance regarding safety. Therefore, due to the high potential in terms of cost and energy density, such as simplification of safety devices during commercialization, it is expected as a next-generation battery, and the development competition is accelerating.

[0003] However, for the practical application and further performance improvement of solid batteries, further development is required, such as active materials that can obtain high capacity and high output, solid electrolytes with high conductivity, optimal design, and process construction. Therefore, it is very important to accurately grasp battery characteristics in various material developments, their combination designs, and manufacturing process studies. In particular, the ability to measure electrical characteristics such as the potential of the positive electrode and / or negative electrode is extremely useful for proceeding with research and development effectively and efficiently. Furthermore, when actually using the battery, if it is possible to measure electrical characteristics such as the potential of each electrode such as the positive electrode and negative electrode during operation, it becomes possible to perform appropriate battery control based on the measured values, and for example, it is also possible to improve performance such as safety and cycle characteristics.

[0004] As a method for examining the potential and electrochemical behavior of a single electrode of each electrode, a three-electrode measurement method using a reference electrode is known. For example, Non-Patent Document 1 describes the configurations of solid batteries capable of three-electrode measurement with various structures. In addition, Patent Document 1 discloses a solid battery including a third electrode as a reference electrode that is in contact with a solid electrolyte portion provided so as to be connected with a width corresponding to the length of the side surface of the solid electrolyte layer or the positive electrode, the solid electrolyte layer, and the negative electrode, in which a positive electrode current collector, a positive electrode, a solid electrolyte layer, a negative electrode, and a negative electrode current collector are laminated.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Non-Patent Document

[0006]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] However, in a solid-state battery, in a conventional battery configuration for performing three-electrode measurement, it has been difficult to fabricate a solid-state battery for performing three-electrode measurement because the structure of the battery is complicated or precise work is required for forming a reference electrode.

[0008] The present disclosure provides a battery or the like capable of easily measuring the electrical characteristics of each electrode.

Means for Solving the Problems

[0009] A battery according to an aspect of the present disclosure includes a power generation element unit having a first electrode layer, a second electrode layer, and a first solid electrolyte layer positioned between the first electrode layer and the second electrode layer, a second solid electrolyte layer having a first main surface in contact with a side surface of the power generation element unit and a second main surface opposite to the first main surface, and a reference electrode unit having a reference electrode in contact with the second main surface of the second solid electrolyte layer. In a stacking direction in the power generation element unit, a length of the first main surface is longer than a length of the side surface.

[0010] A measurement method according to one aspect of the present disclosure is a method for measuring electrical characteristics of a battery including a power generation element unit having a first electrode layer, a second electrode layer, and a first solid electrolyte layer positioned between the first electrode layer and the second electrode layer, the method including: preparing a second solid electrolyte layer having a first main surface and a second main surface opposite to the first main surface, and a reference electrode unit having a reference electrode in contact with the second main surface; bringing the first main surface of the second solid electrolyte layer into contact with a side surface of the power generation element unit; measuring electrical characteristics between at least one of the first electrode layer and the second electrode layer and the reference electrode; and in a stacking direction of the power generation element unit, a length of the first main surface is longer than a length of the side surface.

Advantages of the Invention

[0011] According to the present disclosure, electrical characteristics of each electrode can be easily measured.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2A

Figure 2B

Figure 3

Figure 4A

Figure 4B

Figure 4C

Figure 5A

Figure 5B

Figure 6

Mode for Carrying Out the Invention

[0013] (Summary of the Present Disclosure) The summary of one aspect of the present disclosure is as follows.

[0014] A battery according to one aspect of the present disclosure includes a power generation element portion having a first electrode layer, a second electrode layer, and a first solid electrolyte layer positioned between the first electrode layer and the second electrode layer, a second solid electrolyte layer having a first main surface in contact with a side surface of the power generation element portion and a second main surface opposite to the first main surface, and a reference electrode portion having a reference electrode in contact with the second main surface of the second solid electrolyte layer. In the stacking direction in the power generation element portion, the length of the first main surface is longer than the length of the side surface.

[0015] Thereby, when manufacturing the reference electrode portion, the reference electrode portion can be manufactured with dimensional accuracy such that the length of the first main surface is larger than the length of the side surface so that the side surface can be easily brought into contact with the first main surface. Therefore, a battery having a reference electrode and capable of measuring electrical characteristics such as the potential of each electrode of the battery can be easily manufactured. Thus, according to this aspect, the electrical characteristics of each electrode can be easily measured.

[0016] Further, for example, the first solid electrolyte layer and the second solid electrolyte layer may have lithium ion conductivity.

[0017] Thereby, in a lithium ion battery, the electrical characteristics of each electrode can be easily measured.

[0018] Further, for example, the reference electrode may contain at least one of metallic lithium, a lithium alloy, and a lithium compound.

[0019] Thereby, since the fluctuation of the equilibrium potential is small, the measurement accuracy of the electrical characteristics of each electrode can be improved.

[0020] Further, for example, the battery may include a plurality of the power generation element portions stacked thereon.

[0021] Thereby, even in a stacked battery, the electrical characteristics of each electrode can be easily measured.

[0022] Further, for example, the first main surface may be in contact with a plurality of the power generation element portions.

[0023] Thereby, the electrical characteristics of each electrode of each of the plurality of power generation element portions can be measured. Further, since the first main surface is in contact with a plurality of power generation element portions, the area where the reference electrode portion contacts the power generation element portion can be increased, and the mechanical strength of the battery can be improved.

[0024] Further, for example, the battery may further include an exterior body that covers the power generation element portion and the reference electrode portion.

[0025] Thereby, the power generation element portion and the reference electrode portion are protected and held by the exterior body, and deterioration and breakage of the battery are suppressed, so that the electrical characteristics of each electrode can be stably measured.

[0026] Further, for example, the exterior body has a first cavity extending in a first direction and a second cavity extending in a second direction intersecting the first direction and communicating with the first cavity, the power generation element portion is in contact with an inner surface of the exterior body forming the first cavity, and the reference electrode portion may be in contact with an inner surface of the exterior body forming the second cavity.

[0027] Thereby, even when the power generation element portion and the reference electrode portion expand and contract during charge and discharge, they are held by the exterior body. Further, since the exterior body can easily maintain the pressurized state of the power generation element portion and the reference electrode portion, the measurement accuracy of the electrical characteristics of each electrode of the battery can be improved.

[0028] Further, for example, the shape of at least one of the first cavity and the second cavity may be cylindrical.

[0029] This makes it possible to easily form the first cavity and the second cavity. In addition, when the power generation element portion and the reference electrode portion are formed inside the first cavity and the second cavity, the pressurizing pressure during formation and the stress due to expansion and contraction during charge and discharge of the power generation element portion and the reference electrode portion can be evenly dispersed. Therefore, even with a higher pressure or stress, the exterior body is less likely to be damaged, and the electrical characteristics of each electrode can be stably measured.

[0030] Also, for example, in the exterior body, the portion in contact with the power generation element portion and the reference electrode portion may contain a resin material.

[0031] As a result, since the resin material has excellent workability, an exterior body having a shape adapted to the shapes of the power generation element portion and the reference electrode portion can be easily created.

[0032] Also, for example, the exterior body has a first exterior body portion in contact with the power generation element portion and the reference electrode portion, and a second exterior body portion located outside the first exterior body portion, and the strength of the second exterior body portion may be higher than the strength of the first exterior body portion.

[0033] As a result, even when a high pressure is applied to the power generation element portion, deformation and breakage of the first exterior body portion are suppressed, and the power generation element portion can be appropriately formed. In addition, the pressurized state of the power generation element portion can be maintained even at a higher pressure. Therefore, the electrical characteristics of each electrode of the battery can be stably measured.

[0034] Also, for example, the second exterior body portion may contain a metal material.

[0035] As a result, a second exterior body portion with high strength can be easily formed.

[0036] A current line may be provided between at least one of the first electrode layer or the second electrode layer and the reference electrode.

[0037] As a result, the positive electrode or the negative electrode and the reference electrode are electrically connected, and charge and discharge can be performed.

[0038] There, the characteristics of the battery can be improved by imparting and desorbing lithium ions between the positive electrode or the negative electrode and the reference electrode. For example, it becomes possible to control the charge and discharge capacity, change the rate-determining state of the positive and negative electrodes, change the irreversible capacity, improve the cycle characteristics, and the like.

[0039] In addition, since this operation can be performed dynamically even after the battery is constructed or during use as a power source, more appropriate control for improving characteristics can be performed according to the state of the assembled battery and the operating battery.

[0040] Also, the battery exterior body according to one aspect of the present disclosure is the above-described exterior body.

[0041] In such a battery exterior body, a power generation element portion and a reference electrode portion are formed inside, and the formed power generation element portion and reference electrode portion can be protected and held.

[0042] Also, a measurement method according to one aspect of the present disclosure is a method for measuring the electrical characteristics of a battery including a power generation element portion having a first electrode layer, a second electrode layer, and a first solid electrolyte layer positioned between the first electrode layer and the second electrode layer, the method including preparing a second solid electrolyte layer having a first main surface and a second main surface opposite to the first main surface, and a reference electrode portion having a reference electrode in contact with the second main surface, bringing the first main surface of the second solid electrolyte layer into contact with a side surface of the power generation element portion, measuring the electrical characteristics between at least one of the first electrode layer and the second electrode layer and the reference electrode, and in the stacking direction of the power generation element portion, the length of the first main surface is longer than the length of the side surface.

[0043] Thereby, when manufacturing the reference electrode portion, the reference electrode portion can be manufactured with dimensional accuracy such that the length of the first main surface is larger than the length of the side surface so that the side surface can be easily brought into contact with the first main surface. Therefore, the reference electrode portion can be easily prepared. Thus, the electrical characteristics of each electrode of the battery can be easily and stably measured.

[0044] Hereinafter, embodiments will be specifically described with reference to the drawings.

[0045] Note that all the embodiments described below are illustrative of comprehensive or specific examples. The numerical values, shapes, materials, components, arrangement positions and connection forms of the components, manufacturing processes, order of manufacturing processes, etc. shown in the following embodiments are merely examples and not intended to limit the present disclosure. In addition, among the components in the following embodiments, the components not described in the independent claims are described as optional components.

[0046] Also, each figure is a schematic diagram and is not necessarily drawn precisely. Therefore, for example, the scales in each figure do not necessarily match. Also, in each figure, substantially the same configurations are denoted by the same reference numerals, and overlapping descriptions are omitted or simplified.

[0047] Also, in this specification, terms indicating the relationship between elements such as parallel or orthogonal, terms indicating the shape of elements such as rectangular or circular, and numerical ranges are not expressions representing only a strict meaning, but are expressions meaning substantially equivalent ranges, for example, including a difference of about several percent.

[0048] Also, in this specification and the drawings, the x-axis, y-axis, and z-axis indicate the three axes of a three-dimensional orthogonal coordinate system. In each embodiment, the z-axis direction is the stacking direction perpendicular to the main surface of the power generation element portion. Also, the positive direction of the z-axis is the upper side in the z-axis direction, and the negative direction of the z-axis is the lower side in the z-axis direction. Also, in this specification, "plan view" means the case of viewing the battery along the z-axis. Also, the "thickness" in this specification is the length in the direction perpendicular to the main surface of each layer.

[0049] Also, in this specification, "inner" and "outer" in "inner side" and "outer side", etc. mean that the direction approaching the center of the battery is "inner" and the direction away from the center of the battery is "outer" unless otherwise specified.

[0050] In addition, in this specification, the terms "upper" and "lower" in the battery configuration do not refer to the upward direction (vertically upward) and downward direction (vertically downward) in absolute spatial recognition, but are used as terms defined by the relative positional relationship based on the stacking order in the stacked configuration. Further, the terms "upper" and "lower" are applicable not only when two components are arranged in close contact with each other and the two components are in contact, but also when two components are arranged with a space therebetween and another component exists between the two components.

[0051] (Embodiment 1) First, the battery according to Embodiment 1 will be described.

[0052] [Configuration of Battery] First, the configuration of the battery according to this embodiment will be described. FIG. 1 is a cross-sectional view showing the schematic configuration of a battery 500 according to this embodiment.

[0053] As shown in FIG. 1, the battery 500 includes a solid battery unit 100 including a power generation element unit 50 and a reference electrode unit 150. The battery 500 is, for example, an all-solid-state battery. The shape of the battery 500 is, for example, coin type, laminate type, cylindrical type, or rectangular type.

[0054] The solid battery unit 100 includes a power generation element unit 50, a positive electrode current collector 60, and a negative electrode current collector 70. Further, in the solid battery unit 100, the positive electrode current collector 60 is laminated on the surface of the positive electrode layer 10 opposite to the first solid electrolyte layer 30, and the negative electrode current collector 70 is laminated on the surface of the negative electrode layer 20 opposite to the first solid electrolyte layer 30. That is, the solid battery unit 100 has a structure in which the positive electrode current collector 60, the positive electrode layer 10, the first solid electrolyte layer 30, the negative electrode layer 20, and the negative electrode current collector 70 are laminated in this order. The shape of the solid battery unit 100 is, for example, rectangular parallelepiped shape, polygonal prism shape, or cylindrical shape.

[0055] The power generation element portion 50 has a positive electrode layer 10, a negative electrode layer 20, and a first solid electrolyte layer 30 positioned between the positive electrode layer 10 and the negative electrode layer 20. The positive electrode layer 10 is an example of a first electrode layer, and the negative electrode layer 20 is an example of a second electrode layer. In the power generation element portion 50, the positive electrode layer 10, the first solid electrolyte layer 30, and the negative electrode layer 20 are laminated in this order.

[0056] The reference electrode portion 150 has a second solid electrolyte layer 130 having a first main surface 130a in contact with the side surface 50a of the power generation element portion 50, and a second main surface 130b opposite to the first main surface 130a, and a reference electrode 110 in contact with the second main surface 130b.

[0057] Hereinafter, details of each component constituting the battery 500 will be described.

[0058] The power generation element portion 50 is positioned between the positive electrode current collector 60 and the negative electrode current collector 70. The side surface 50a of the power generation element portion 50 is in contact with the reference electrode portion 150, specifically, the first main surface 130a of the second solid electrolyte layer 130. The side surface 50a is a surface connecting the ends of the two main surfaces of the power generation element portion 50, and in FIG. 1, it is a plane parallel to the stacking direction in the power generation element portion 50. The side surface 50a may be inclined with respect to the stacking direction in the power generation element portion 50. The stacking direction in the power generation element portion 50 is the stacking direction of each layer constituting the power generation element portion 50, that is, the direction in which the positive electrode layer 10, the first solid electrolyte layer 30, and the negative electrode layer 20 are stacked.

[0059] The shape of the power generation element portion 50 is, for example, a rectangular parallelepiped shape, a polygonal column shape, or a cylindrical shape.

[0060] The positive electrode layer 10 is positioned between the positive electrode current collector 60 and the first solid electrolyte layer 30, and is in contact with the positive electrode current collector 60 and the first solid electrolyte layer 30. Also, the side surface of the positive electrode layer 10 on the reference electrode portion 150 side is in contact with the second solid electrolyte layer 130, specifically, the first main surface 130a.

[0061] The positive electrode layer 10 contains at least a positive electrode active material. As the material of the positive electrode layer 10, in addition to the positive electrode active material, a positive electrode mixture containing at least one of a solid electrolyte, a conductive assistant, and a binder material may be used as needed.

[0062] As the positive electrode active material, known materials capable of occluding and releasing (inserting and desorbing, or dissolving and precipitating) metal ions such as lithium ions, sodium ions, magnesium ions, potassium ions, calcium ions, or copper ions can be used.

[0063] Examples of the positive electrode active material include lithium-containing transition metal oxides, lithium-free transition metal oxides, transition metal fluorides, polyanion materials, fluorinated polyanion materials, transition metal sulfides, transition metal oxyfluorides, transition metal oxysulfides, and transition metal oxynitrides. When a lithium-containing transition metal oxide is used as the positive electrode active material, the manufacturing cost of the battery can be reduced and the average discharge voltage of the battery can be increased.

[0064] In the case of a material capable of releasing and inserting lithium ions as the positive electrode active material, for example, lithium cobalt composite oxide (LCO), lithium nickel composite oxide (LNO), lithium manganese composite oxide (LMO), lithium-manganese-nickel composite oxide (LMNO), lithium-manganese-cobalt composite oxide (LMCO), lithium-nickel-cobalt composite oxide (LNCO), or lithium-nickel-manganese-cobalt composite oxide (LNMCO) is used. Specific positive electrode active materials include, for example, LiCoO2, LiMn2O4, Li2NiMn3O8, LiVO2, LiCrO2, LiFePO4, LiCoPO4, LiNiO2, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2, LiNi x Mn y Al z O2, LiNi x Co y Mn z and LiNi x Coy Al z Examples include the following.

[0065] As the solid electrolyte, known materials that conduct metal ions such as lithium ions, sodium ions, magnesium ions, potassium ions, calcium ions, copper ions, or silver ions, or protons, etc. can be used. As the solid electrolyte, for example, solid electrolyte materials such as sulfide solid electrolytes, halogen-based solid electrolytes, oxide solid electrolytes, or polymer solid electrolytes are used.

[0066] In the case of a material capable of conducting lithium ions as the sulfide solid electrolyte, for example, a composite (Li2S-P2S5) composed of lithium sulfide (Li2S) and phosphorus pentasulfide (P2S5) is used. Also, as the sulfide solid electrolyte, Li2S-P2S5, Li2S-P2S5-LiBH4, Li7P3S 11 , Li2S-SiS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li4SiO4, Li2S-B2S3, Li2S-GeS2, Li6PS5Cl, LiSiPSCl, and sulfides such as sulfides containing Li3N or Li3N(H) can be mentioned. Also, as the sulfide solid electrolyte, sulfides to which at least one of Li3N, LiCl, LiBr, LiI, Li3PO4, and Li4SiO4 is added as an additive to the above sulfides may be used. Also, as other specific sulfide solid electrolytes, Li 10 GeP2S 12 (LGPS), Na3Zr2(SiO4)2PO4 (NASICON), etc. can be mentioned.

[0067] In the case of a material capable of conducting lithium ions as the oxide solid electrolyte, for example, Li7La3Zr2O 12 (LLZ), Li 1.3 Al 0.3 Ti 1.7 (PO4)3 (LATP) or (La,Li)TiO3 (LLTO), etc. are used.

[0068] The halogen-based solid electrolyte is a solid electrolyte containing a halide. The halide is, for example, a compound composed of Li, M’, and X’. M’ is at least one element selected from the group consisting of metal elements other than Li and metalloid elements. X’ is at least one element selected from the group consisting of F, Cl, Br, and I. The “metal element” represents all elements contained in Groups 1 to 12 of the periodic table (excluding hydrogen), and all elements contained in Groups 13 to 16 of the periodic table (excluding B, Si, Ge, As, Sb, Te, C, N, P, O, S, and Se). The “metalloid element” represents B, Si, Ge, As, Sb, and Te. For example, M’ may contain Y (yttrium). Examples of halides containing Y include Li3YCl6 and Li3YBr6.

[0069] Examples of other halides include, for example, Li2MgX’4, Li2FeX’4, Li(Al,Ga,In)X’4, Li3(Al,Ga,In)X’6, LiOX’, and LiX’. Specifically, examples of halides include, for example, Li3InBr6, Li3InCl6, Li2FeCl4, Li2CrCl4, Li3OCl, and LiI.

[0070] The polymer solid electrolyte is not particularly limited as long as it is a solid electrolyte containing a polymer material having ionic conductivity. Examples of the polymer material having ionic conductivity include polyethers, polyether derivatives, polyesters, polyimines, and the like.

[0071] In addition, as the solid electrolyte, in addition to the above solid electrolyte materials, thin film-based solid charge materials such as lithium phosphorus oxynitride (LIPON) may also be used.

[0072] In the positive electrode layer 10, the volume ratio of the positive electrode active material to the total of the volume of the positive electrode active material and the volume of the solid electrolyte is, for example, 30% or more and 95% or less. Further, the volume ratio of the solid electrolyte to the total of the volume of the positive electrode active material and the volume of the solid electrolyte is, for example, 5% or more and 70% or less. When the amounts of the positive electrode active material and the solid electrolyte are in such volume ratios, it becomes easier to sufficiently secure the energy density of the battery 500 and to operate the battery 500 at high output.

[0073] As the binder material, the same materials as those used in general solid batteries can be used. Examples of the binder material include polyvinylidene fluoride, polytetrafluoroethylene, polyethylene, polypropylene, aramid resin, polyamide, polyimide, polyamideimide, polyacrylonitrile, polyallylic acid, methyl polyacrylate ester, ethyl polyacrylate ester, hexyl polyacrylate ester, polymethacrylic acid, methyl polymethacrylate ester, ethyl polymethacrylate ester, hexyl polymethacrylate ester, polyvinyl acetate, polyvinyl pyrrolidone, polyether, polyether sulfone, hexafluoropolypropylene, styrene butadiene rubber, carboxymethyl cellulose, polyaniline, polythiophene styrene butadiene rubber, and polyacrylate. Further, as the binder material, a copolymer of two or more materials selected from tetrafluoroethylene, hexafluoroethylene, hexafluoropropylene, perfluoroalkyl vinyl ether, vinylidene fluoride, chlorotrifluoroethylene, ethylene, propylene, pentafluoropropylene, fluoromethyl vinyl ether, acrylic acid, and hexadiene may be used.

[0074] Examples of the conductive aid include graphite such as natural graphite and artificial graphite, carbon black such as acetylene black, furnace black, and Ketjenblack (registered trademark), conductive fibers such as VGCF, carbon nanotubes, carbon nanofibers, fullerenes, carbon fibers, and metal fibers, metal powders such as carbon fluoride and aluminum powder, conductive whiskers such as zinc oxide whiskers and potassium titanate whiskers, conductive metal oxides such as titanium oxide, and conductive polymer compounds such as polyaniline, polypyrrole, and polythiophene.

[0075] The shape of the conductive aid is, for example, needle-like, scaly, spherical, or ellipsoidal. The conductive aid may be in the form of particles.

[0076] The thickness of the positive electrode layer 10 is, for example, 10 μm or more and 500 μm or less. When the thickness of the positive electrode layer 10 is within such a range, it becomes easier to sufficiently ensure the energy density of the battery 500 and to operate the battery 500 at high output.

[0077] Examples of the method for forming the positive electrode layer 10 include a method of uniaxially compression molding a powder positive electrode mixture. Further, the first solid electrolyte layer 30 may be produced by coating and drying a paste-like paint obtained by kneading a positive electrode mixture together with a solvent on a substrate, the first solid electrolyte layer 30, or a positive electrode current collector 60 or the like.

[0078] The negative electrode layer 20 is located between the negative electrode current collector 70 and the first solid electrolyte layer 30 and is in contact with the negative electrode current collector 70 and the first solid electrolyte layer 30. Further, the side surface of the negative electrode layer 20 on the reference electrode portion 150 side is in contact with the second solid electrolyte layer 130, specifically, the first main surface 130a.

[0079] The negative electrode layer 20 contains at least a negative electrode active material. As the material of the negative electrode layer 20, in addition to the negative electrode active material, a negative electrode mixture containing at least one of a solid electrolyte, a conductive aid, and a binder material may be used as necessary.

[0080] As the negative electrode active material, known materials capable of occluding and releasing (inserting and extracting, or dissolving and depositing) metal ions such as lithium ions, sodium ions, magnesium ions, potassium ions, calcium ions, or copper ions can be used. Examples of the negative electrode active material include metal materials, carbon materials, oxides, nitrides, tin compounds, and silicon compounds.

[0081] In the case of a material capable of releasing and inserting lithium ions as the negative electrode active material, for example, carbon materials such as natural graphite, artificial graphite, graphite carbon fiber, or resin-fired carbon, metallic lithium, lithium alloy, or oxides of lithium and transition metal elements are used. Examples of the metal used for the lithium alloy include indium, aluminum, silicon, germanium, tin, and zinc. Specific examples of the oxides of lithium and transition metal elements include Li4Ti5O 12 and Li x SiO, etc.

[0082] As the solid electrolyte of the negative electrode layer 20, the above-described solid electrolyte materials can be used. As the conductive assistant of the negative electrode layer 20, the above-described conductive materials can be used. As the binder material of the negative electrode layer 20, the above-described binder materials can be used.

[0083] In the negative electrode layer 20, the volume ratio of the negative electrode active material to the total of the volume of the negative electrode active material and the volume of the solid electrolyte is, for example, 30% or more and 95% or less. Also, the volume ratio of the solid electrolyte to the total of the volume of the negative electrode active material and the volume of the solid electrolyte is, for example, 5% or more and 70% or less. By having the amounts of the negative electrode active material particles and the solid electrolyte in such volume ratios, the energy density of the battery 500 can be sufficiently ensured, and the battery 500 can be easily operated at high output.

[0084] The thickness of the negative electrode layer 20 is, for example, 10 μm or more and 500 μm or less. By having the thickness of the negative electrode layer 20 within such a range, it becomes easier to sufficiently ensure the energy density of the battery 500, and it becomes easier to operate the battery 500 at high output.

[0085] As a method for forming the negative electrode layer 20, for example, a method of uniaxially compression-molding a powdered negative electrode binder or the like can be mentioned. Further, the negative electrode layer 20 may be produced by applying and drying a paste-like paint in which a negative electrode binder is kneaded together with a solvent onto a substrate, the first solid electrolyte layer 30, the negative electrode current collector 70, or the like.

[0086] The first solid electrolyte layer 30 is located between the positive electrode layer 10 and the negative electrode layer 20 and is in contact with the positive electrode layer 10 and the negative electrode layer 20. Further, the side surface of the first solid electrolyte layer 30 on the reference electrode portion 150 side is in contact with the second solid electrolyte layer 130, specifically, the first main surface 130a.

[0087] The first solid electrolyte layer 30 has conductivity for metal ions such as lithium ions, sodium ions, magnesium ions, potassium ions, calcium ions, or copper ions. The first solid electrolyte layer 30 may have lithium ion conductivity.

[0088] The first solid electrolyte layer 30 contains at least a solid electrolyte and may contain a binder material as necessary. Further, the first solid electrolyte layer 30 may contain a solid electrolyte having lithium ion conductivity.

[0089] As the solid electrolyte of the first solid electrolyte layer 30, the above-mentioned solid electrolyte materials can be used. One type of solid electrolyte may be used for the first solid electrolyte layer 30, or two or more types of solid electrolytes may be used. Further, as the binder material of the first solid electrolyte layer 30, the above-mentioned binder materials can be used.

[0090] The thickness of the first solid electrolyte layer 30 is, for example, 0.1 μm or more and 1000 μm or less. From the viewpoint of improving the energy density of the battery 500, the thickness of the first solid electrolyte layer 30 may be 0.1 μm or more and 50 μm or less.

[0091] As a method for forming the first solid electrolyte layer 30, for example, a method of uniaxially compression-molding the material containing the powder of the first solid electrolyte layer 30 can be mentioned. Further, the first solid electrolyte layer 30 may be produced by applying and drying a paste-like paint in which the material containing the first solid electrolyte layer 30 is kneaded together with a solvent onto a substrate, the positive electrode layer 10, the negative electrode layer 20, or the like.

[0092] The side surface of the positive electrode layer 10, the side surface of the negative electrode layer 20, and the side surface of the first solid electrolyte layer 30 are flush with each other and constitute the side surface 50a. Note that the side surface of the positive electrode layer 10, the side surface of the negative electrode layer 20, and the side surface of the first solid electrolyte layer 30 do not have to be flush with each other. For example, the first solid electrolyte layer 30 may cover the side surfaces of the positive electrode layer 10 and the negative electrode layer 20, and the side surface 50a may be constituted only by the side surface of the first solid electrolyte layer 30.

[0093] The positive electrode current collector 60 is located on the positive electrode layer 10 and is in contact with the positive electrode layer 10. Further, the negative electrode current collector 70 is located under the negative electrode layer 20 and is in contact with the negative electrode layer 20. The side surfaces of the positive electrode current collector 60 and the negative electrode current collector 70 are in contact with the first main surface 130a.

[0094] As materials for the positive electrode current collector 60 and the negative electrode current collector 70, for example, highly conductive metal materials such as copper, aluminum, nickel, iron, stainless steel, platinum, or gold, alloys of two or more of these, or those obtained by plating any of these can be mentioned. The positive electrode current collector 60 and the negative electrode current collector 70 may be made of the same material or different materials.

[0095] The shapes of the positive electrode current collector 60 and the negative electrode current collector 70 are not particularly limited as long as they are set according to the shape of the battery 500 or the like. The shapes of the positive electrode current collector 60 and the negative electrode current collector 70 are, for example, rod-shaped, plate-shaped, sheet-shaped, foil-shaped, or mesh-shaped.

[0096] The thicknesses of the positive electrode current collector 60 and the negative electrode current collector 70 are, for example, 1 μm or more and 10 mm or less. Further, depending on the shape of the battery 500, the thicknesses of the positive electrode current collector 60 and the negative electrode current collector 70 may be 10 mm or more.

[0097] The second solid electrolyte layer 130 is located between the reference electrode 110 and the power generation element portion 50. The second solid electrolyte layer 130 has a first main surface 130a and a second main surface 130b.

[0098] The first main surface 130a is in contact with the side surface 50a of the power generation element portion 50. Specifically, the first main surface 130a is in contact with all of the side surfaces on the reference electrode portion 150 side of the positive electrode layer 10, the negative electrode layer 20, and the first solid electrolyte layer 30 that constitute the power generation element portion 50. In other words, the first main surface 130a is in contact with the region extending from one end to the other end of the side surface 50a in the stacking direction (z-axis direction). The first main surface 130a is further in contact with the positive electrode current collector 60 and the negative electrode current collector 70. In the stacking direction of the power generation element portion 50, the length L2 of the first main surface 130a is longer than the length L1 of the side surface 50a in contact with the first main surface 130a. The length L1 is the length of the side surface 50a at the location where the side surface 50a is in contact with the first main surface 130a. Also, the second main surface 130b is in contact with the reference electrode 110.

[0099] As the material constituting the second solid electrolyte layer 130, a material similar to that of the first solid electrolyte layer 30 can be used. Also, the same material may be used for the first solid electrolyte layer 30 and the second solid electrolyte layer 130, or different materials may be used. For the second solid electrolyte layer 130, one type of solid electrolyte may be used, or two or more types of solid electrolytes may be used.

[0100] Also, the thickness of the second solid electrolyte layer 130 is, for example, 10 μm or more and 10 mm or less.

[0101] The reference electrode 110 is in contact with the second main surface 130b of the second solid electrolyte layer 130. In FIG. 1, the reference electrode 110 is in contact with the entire surface of the second main surface 130b. Note that the reference electrode 110 does not necessarily have to be in contact with the entire surface of the second main surface 130b, and the reference electrode 110 may be provided so as to be in contact with a partial region on the second main surface 130b.

[0102] As the material of the reference electrode 110, any material can be used without particular limitation as long as it is in electrochemical contact with the second solid electrolyte layer 130 and exhibits an equilibrium potential. The reference electrode 110 includes, for example, at least one of metallic lithium, a lithium alloy, and a lithium compound. From the viewpoint of measurement accuracy, a material with a small variation in equilibrium potential may be used as the material of the reference electrode 110. Examples of materials with a small variation in equilibrium potential include metallic lithium, lithium alloys such as In-Li, and 12 lithium compounds such as Li4Ti5O

[0103] The planar shapes of the positive electrode layer 10, the negative electrode layer 20, the first solid electrolyte layer 30, the positive electrode current collector 60, the negative electrode current collector 70, the second solid electrolyte layer 130, and the reference electrode 110 are, for example, circular, rectangular, or polygonal, respectively.

[0104] The manufacturing method of the battery 500 according to the present embodiment can use the same method as the general battery manufacturing method except for providing the second solid electrolyte layer 130 and the reference electrode 110. For example, first, the power generation element unit 50 is manufactured by sequentially pressing and compression molding the powders of the material constituting the positive electrode layer 10, the material constituting the first solid electrolyte layer 30, and the material constituting the negative electrode layer 20. Further, before or after manufacturing the power generation element unit 50, the second solid electrolyte layer 130 is formed by pressing and compression molding the material constituting the second solid electrolyte layer 130, and the reference electrode 110 is disposed on the formed second solid electrolyte layer 130, or the reference electrode unit 150 is manufactured by pressing and compression molding the material constituting the reference electrode 110. Then, the battery 500 can be manufactured by bringing the first main surface 130a of the second solid electrolyte layer 130 into contact with the side surface 50a of the power generation element unit 50. Further, the reference electrode unit 150 may be directly formed on the side surface 50a of the power generation element unit 50.

[0105] [Method for Measuring Electrical Characteristics of Battery] Next, the method for measuring the electrical characteristics of the battery 500 according to the present embodiment will be described. Specifically, the method for measuring the electrical characteristics of the battery 500 including the power generation element unit 50 will be described with reference to FIGS. 2A and 2B.

[0106] FIG. 2A and FIG. 2B are diagrams for explaining a method of measuring the electrical characteristics of the battery 500.

[0107] As shown in FIG. 2A, first, the power generation element portion 50 and the reference electrode portion 150 are prepared using the above-described manufacturing method and the like. Then, the first main surface 130a of the second solid electrolyte layer 130 is brought into contact with the side surface 50a of the power generation element portion 50. As a result, as shown in FIG. 2B, the battery 500 is formed. As described above, when brought into contact, in the stacking direction of the power generation element portion 50, the length of the first main surface 130a is longer than the length of the side surface 50a. That is, when preparing the reference electrode portion 150, a reference electrode portion 150 having a second solid electrolyte layer 130 having a first main surface 130a whose length (length L2 in the present embodiment) in at least one direction is longer than the length L1 of the side surface 50a in the stacking direction of the power generation element portion 50 is prepared.

[0108] Then, for example, as shown in FIG. 2B, a voltage measuring device 91, 92, and 93 is electrically connected to each of the positive electrode layer 10 and the negative electrode layer 20, the positive electrode layer 10 and the reference electrode 110, and the negative electrode layer 20 and the reference electrode 110. As a result, the voltage V1 between the positive electrode layer 10 and the negative electrode layer 20, the voltage V2 between the positive electrode layer 10 and the reference electrode 110, and the voltage V3 between the negative electrode layer 20 and the reference electrode 110 can be measured. In this way, electrical characteristics such as the voltage between at least one of the positive electrode layer 10 and the negative electrode layer 20 and the reference electrode 110 are measured. Also, as the electrical characteristics, electrical characteristics other than voltage such as impedance may be measured.

[0109] At this time, regardless of the operation of the positive electrode layer 10 and the negative electrode layer 20, since the reference electrode 110 shows a constant value as the equilibrium potential with the second solid electrolyte layer 130, the potential of the positive electrode layer 10 and / or the negative electrode layer 20 can be measured as the voltage difference between the reference electrode 110 and the positive electrode layer 10 and / or the negative electrode layer 20.

[0110] As disclosed in Non-Patent Document 1, various structures of solid-state batteries having conventional reference electrodes have been studied, but their structures are complex and not easy to form.

[0111] In addition, the solid-state battery having the reference electrode disclosed in Patent Document 1 has a structure in which a positive electrode, a solid electrolyte layer, and a negative electrode are laminated, and a third electrode as a reference electrode that is in contact with a solid electrolyte portion provided so as to be connected with a width corresponding to the length of the side surface of the solid electrolyte layer, or the positive electrode, the solid electrolyte layer, and the negative electrode is provided, and it is possible to measure the potential of the positive electrode and / or the negative electrode.

[0112] However, it is not easy to form the solid electrolyte portion so as to match the length of the side surface of the solid electrolyte layer, or the positive electrode, the solid electrolyte layer, and the negative electrode as in the structure shown in Patent Document 1. In addition, although a solid-state battery is more suitable when both the electrode and the solid electrolyte layer are thinner because the characteristics are better, in the case of such a thin-layered solid-state battery, there is a problem that it becomes even more difficult to form the solid electrolyte portion.

[0113] In addition, in order to operate the formed solid-state battery, it is generally necessary to put the solid-state battery in a pressurized state, but it is not easy to pressurize the complex structures shown in Non-Patent Document 1 and Patent Document 1 while maintaining their functions and measure the characteristics of the battery and the electrodes.

[0114] In this embodiment, in order to perform three-terminal measurement, the second solid electrolyte layer 130 that contacts the power generation element portion 50 does not necessarily have a structure in which the length of the first main surface 130a precisely matches the side surface 50a in the stacking direction of the power generation element portion 50, and it has been found that it is sufficient if it can be electrochemically contacted with the power generation element portion 50. Therefore, as shown in FIG. 1, the battery 500 includes a power generation element portion 50 and a reference electrode portion 150, and has a structure in which the length L2 of the first main surface 130a of the second solid electrolyte layer 130 is longer than the length L1 of the side surface 50a of the power generation element portion 50 in the stacking direction of the power generation element portion 50. Thereby, when manufacturing the reference electrode portion 150, the reference electrode portion 150 can be manufactured with dimensional accuracy such that the length L2 of the first main surface 130a is larger than the length L1 of the side surface 50a so that the side surface 50a can be easily brought into contact with the first main surface 130a. Therefore, the battery 500 capable of measuring electrical characteristics such as the potentials of the positive electrode layer 10 and the negative electrode layer 20 can be easily manufactured. Thus, the electrical characteristics of the electrodes can be easily measured by the battery 500 and the method for measuring the electrical characteristics of the battery 500.

[0115] By being able to easily measure the potential of the positive electrode layer 10 and / or the negative electrode layer 20 alone using the battery 500 according to this embodiment, in the development of the battery, the electrical characteristics of the positive electrode layer 10 and / or the negative electrode layer 20 can be grasped, and since the electrical characteristics can be measured separately for both the positive electrode layer 10 and the negative electrode layer 20, the development and design of the battery can be promoted effectively and efficiently.

[0116] Also, when the battery 500 according to this embodiment is applied and developed to a practical battery, for example, the following effects can be realized. In the positive electrode layer 10, for example, when the structure of the active material changes at a certain potential or higher and the electrode performance such as the charge-discharge capacity and cycle characteristics deteriorates, the potential of the positive electrode layer 10 can be monitored and controlled so as not to exceed that potential. As a result, in the battery 500, deterioration of the electrode performance due to charging can be prevented. Also, in the negative electrode layer 20, for example, in the case of an electrode used up to near the lithium metal deposition potential during charging, the lithium metal deposition potential (for example, 0 V or less, vs. Li +By performing monitoring and control so as not to reach (Li), precipitation of metallic lithium can be prevented. As a result, in the battery 500, it is possible to reduce a decrease in charge / discharge capacity, shortening of the battery life due to cycle deterioration, and risks such as a short-circuit phenomenon, heating, and ignition associated with the precipitation of metallic lithium.

[0117] (Embodiment 2) Next, the battery according to Embodiment 2 will be described.

[0118] The battery according to Embodiment 2 mainly differs from Embodiment 1 in that it includes a plurality of stacked power generation element portions. Hereinafter, the description will focus on the differences from Embodiment 1, and the description of the common points will be omitted or simplified.

[0119] FIG. 3 is a cross-sectional view showing a schematic configuration of a battery 501 according to the present embodiment. The battery 501 includes a solid battery portion 101 instead of the solid battery portion 100 as compared with the battery 500 according to Embodiment 1.

[0120] As shown in FIG. 3, the battery 501 according to the present embodiment includes a solid battery portion 101 including a plurality of stacked power generation element portions 50, and a reference electrode portion 150.

[0121] The solid battery portion 101 includes a plurality of power generation element portions 50 stacked in parallel through a current collector (a positive electrode current collector 60 in FIG. 3). The solid battery portion 101 also includes a positive electrode current collector 60 located between the plurality of power generation element portions 50 and a negative electrode current collector 70 located on the side opposite to the power generation element portion 50 side of each of the plurality of power generation element portions 50. In the solid battery portion 101, among the power generation element portions 50 adjacent in the stacking direction, the positive electrode layer 10 of the upper power generation element portion 50 and the positive electrode layer 10 of the lower power generation element portion 50 are in contact with the positive electrode current collector 60 between the adjacent power generation element portions 50, and thus the plurality of power generation element portions 50 are stacked. That is, the solid battery portion 101 has a structure in which the plurality of power generation element portions 50 are stacked with the same-pole layers of the adjacent power generation element portions 50 facing each other through the current collector, with the vertical direction being alternately reversed.

[0122] The first major surface 130a of the second solid electrolyte layer 130 is in contact with the respective side surfaces 50a of the plurality of power generation element portions 50. Thus, since the first major surface 130a is in contact with the plurality of power generation element portions 50, the area where the reference electrode portion 150 contacts the power generation element portion 50 can be increased, and the mechanical strength of the battery 501 can be improved. In FIG. 3, the first major surface 130a is in contact with all of the side surfaces 50a of the plurality of power generation element portions 50, but there may be a power generation element portion 50 having a side surface 50a that is not in contact with the first major surface 130a.

[0123] Even in such a battery 501, by providing the reference electrode portion 150, it is possible to measure electrical characteristics such as the electrode potential of at least one of the plurality of positive electrode layers 10 and negative electrode layers 20 laminated in a parallel circuit manner. Therefore, similar to the battery 500, it is possible to easily measure electrical characteristics such as the potential behavior of each independent positive electrode layer 10 and negative electrode layer 20.

[0124] In FIG. 3, the power generation element portions 50 are laminated such that the positive electrode current collector 60 and the positive electrode layer 10 are in contact with both surfaces of one positive electrode current collector 60, but a configuration in which the positive electrode layer 10 and the negative electrode layer 20 are reversed may also be used. Further, in FIG. 3, the solid battery portion 101 includes two power generation element portions 50, but may include three or more power generation element portions 50 laminated in a parallel circuit manner. Further, when the solid battery portion 101 includes three or more power generation element portions 50, the battery 501 may include a plurality of reference electrode portions 150, and each of the first major surfaces 130a of the plurality of reference electrode portions 150 may be in contact with the side surface 50a of at least one of the three or more power generation element portions 50.

[0125] (Embodiment 3) Next, a battery according to Embodiment 3 will be described.

[0126] The battery according to Embodiment 3 mainly differs from Embodiment 1 in that it further includes an exterior body. Hereinafter, the description will focus on the differences from Embodiment 1 and Embodiment 2, and the description of the common points will be omitted or simplified.

[0127] FIG. 4A is a top view showing a schematic configuration of the battery 502 according to the present embodiment. FIG. 4B is a cross-sectional view showing a schematic configuration of the battery 502 according to the present embodiment. FIG. 4B shows a cross-section of the battery 502 at the position indicated by the line IVb-IVb in FIG. 4A. FIG. 4C is a side view showing a schematic configuration of the battery 502 according to the present embodiment. FIG. 4C shows a side view of the battery 502 when viewed from the reference electrode portion 152 side (i.e., the positive x-axis direction side) of the solid battery portion 102. The battery 502 includes a solid battery portion 102 and a reference electrode portion 152 instead of the solid battery portion 100 and the reference electrode portion 150 as compared with the battery 500 according to the first embodiment. Further, the battery 502 further includes an exterior body 200 and a reference electrode current collector 160 as compared with the battery 500 according to the first embodiment.

[0128] As shown in FIGS. 4A, 4B, and 4C, the battery 502 includes a solid battery portion 102 including a power generation element portion 52, a reference electrode portion 152, a reference electrode current collector 160, and an exterior body 200 that covers the power generation element portion 52 and the reference electrode portion 152 and has a first cavity 210 and a second cavity 220. The shape of the battery 502 is cylindrical.

[0129] The solid battery portion 102 includes a power generation element portion 52, a positive electrode current collector 62, and a negative electrode current collector 72. The solid battery portion 102 has a structure in which a positive electrode current collector 62, a positive electrode layer 12, a first solid electrolyte layer 32, a negative electrode layer 22, and a negative electrode current collector 72 are laminated in this order. The shape of the solid battery portion 102 is cylindrical. Note that the solid battery portion 102 may include a plurality of power generation element portions 52 laminated via current collectors.

[0130] The power generation element portion 52 has a positive electrode layer 12, a negative electrode layer 22, and a first solid electrolyte layer 32 located between the positive electrode layer 12 and the negative electrode layer 22. The power generation element portion 52 is located inside the first cavity 210 and is in contact with the inner surface 210a of the exterior body 200 that forms the first cavity 210. Specifically, among the side surfaces 52a of the power generation element portion 52, the portions that are not in contact with the first main surface 132a are in contact with the inner surface 210a. The shape of the power generation element portion 52 is cylindrical.

[0131] The reference electrode portion 152 has a second solid electrolyte layer 132 having a first main surface 132a in contact with the side surface 52a of the power generation element portion 52 and a second main surface 132b opposite to the first main surface 132a, and a reference electrode 112 in contact with the second main surface 132b. The reference electrode portion 152 is located inside the second cavity 220 and is in contact with the inner surface 220a of the exterior body 200 that forms the second cavity 220. Specifically, the side surface of the reference electrode portion 152 (in other words, the surface parallel to the stacking direction in the reference electrode portion 152) is in contact with the inner surface 220a. The shape of the reference electrode portion 152 is cylindrical.

[0132] In this way, since the power generation element portion 52 and the reference electrode portion 152 are in contact with the inner surface 210a and the inner surface 220a respectively, even if the power generation element portion 52 and the reference electrode portion 152 expand and contract during charge and discharge, they are held by the exterior body 200. Further, since the exterior body 200 can easily maintain the pressurized state of the power generation element portion 52 and the reference electrode portion 152, the measurement accuracy of the electrical characteristics of each electrode of the battery 502 can be improved.

[0133] The positive electrode current collector 62 is located inside the first cavity 210. The side surface of the positive electrode current collector 62 is in contact with the inner surface 210a. The upper surface of the positive electrode current collector 62 and the upper surface of the exterior body 200 are flush. Note that the upper surface of the positive electrode current collector 62 may be located inside the first cavity 210. Also, the positive electrode current collector 62 may protrude from the upper surface of the exterior body 200.

[0134] The negative electrode current collector 72 is located inside the first cavity 210. The side surface of the negative electrode current collector 72 is in contact with the inner surface 210a. The lower surface of the negative electrode current collector 72 and the lower surface of the exterior body 200 are flush. Note that the lower surface of the negative electrode current collector 72 may be located inside the first cavity 210. Also, the negative electrode current collector 72 may protrude from the lower surface of the exterior body 200.

[0135] The reference electrode current collector 160 is located on the side opposite to the second solid electrolyte layer 132 side of the reference electrode 112 and is in contact with the reference electrode 112. Note that the position where the reference electrode current collector 160 contacts the reference electrode 112 is not particularly limited. As long as the reference electrode current collector 160 is a surface other than the surface where the reference electrode 112 contacts the second solid electrolyte layer 132, it may be in contact with any surface. Further, the reference electrode current collector 160 is in contact with the entire surface on the side opposite to the second solid electrolyte layer 132 side of the reference electrode 112, but it may also be in contact with a part of the surface on the side opposite to the second solid electrolyte layer 132 side of the reference electrode 112.

[0136] Further, the reference electrode current collector 160 is located inside the second cavity 220. The surface of the reference electrode current collector 160 on the side opposite to the reference electrode 112 side is flush with the outer surface of the exterior body 200. Note that the surface of the reference electrode current collector 160 on the side opposite to the reference electrode 112 side may be located inside the second cavity 220. Also, the reference electrode current collector 160 may protrude from the outer surface of the exterior body 200.

[0137] Examples of the material of the reference electrode current collector 160 include highly conductive metal materials such as copper, aluminum, nickel, iron, stainless steel, platinum, or gold, alloys of two or more of these, or those obtained by plating any of these.

[0138] The shape of the reference electrode current collector 160 is not particularly limited because it may be set according to the shapes of the battery 502 and the exterior body 200, etc. The shape of the reference electrode current collector 160 is, for example, rod-shaped, plate-shaped, sheet-shaped, foil-shaped, or mesh-shaped, etc.

[0139] The thickness of the reference electrode current collector 160 is, for example, 1 μm or more and 10 mm or less. Also, depending on the shapes of the battery 502 and the exterior body 200, the thickness of the reference electrode current collector 160 may be 10 mm or more.

[0140] The planar shapes of the positive electrode layer 12, the negative electrode layer 22, the first solid electrolyte layer 32, the positive electrode current collector 62, the negative electrode current collector 72, the second solid electrolyte layer 132, the reference electrode 112, and the reference electrode current collector 160 are each circular, but are not limited thereto, and may be rectangular, polygonal, or the like.

[0141] The battery 502 may further include extraction terminals electrically connected to the positive electrode current collector 62, the negative electrode current collector 72, and the reference electrode current collector 160, respectively. As the material of the extraction terminals, any material having conductivity may be used, and materials generally used for batteries are used. Examples of the material of the extraction terminals include copper, aluminum, and stainless steel. In addition, examples of the shape of the extraction terminals include a foil shape and a lead shape. Note that the positive electrode current collector 62, the negative electrode current collector 72, and the reference electrode current collector 160 may also serve as the extraction terminals.

[0142] The exterior body 200 is a battery exterior body in which the power generation element portion 52 and the reference electrode portion 152 are formed inside and which holds the power generation element portion 52 and the reference electrode portion 152. The shape of the exterior body 200 is not particularly limited as long as it can cover the power generation element portion 52 and the reference electrode portion 152. In the illustrated example, the shape of the exterior body 200 is a columnar shape having a cavity for forming the power generation element portion 52 and the reference electrode portion 152 inside. The shape of the exterior body 200 may be a rectangular parallelepiped shape, a polygonal columnar shape, or the like.

[0143] The exterior body 200 has a first cavity 210 extending in a first direction and a second cavity 220 extending in a second direction intersecting the first direction and connected to the first cavity 210. In the illustrated example, the first direction is the stacking direction (z-axis direction) in the power generation element portion 52, and the second direction is the normal direction (x-axis direction) of the side surface 52a of the power generation element portion 52. In the present embodiment, the first direction and the second direction are orthogonal to each other. The first cavity 210 is located at the center of the exterior body 200 when viewed from the first direction and is a hole penetrating the exterior body 200. The second cavity 220 is located at the center of the exterior body 200 when viewed from the second direction and is a hole reaching the first cavity 210 from the outer surface of the exterior body 200.

[0144] The side surface 52a of the power generation element portion 52 located inside the first cavity 210 and the first main surface 132a of the second solid electrolyte layer 132 in the reference electrode portion 152 located inside the second cavity 220 are in contact with each other at the intersection of the first cavity 210 and the second cavity 220 where the first cavity 210 and the second cavity 220 are connected. The shapes of the first cavity 210 and the second cavity 220 are cylindrical. Since the shapes of the first cavity 210 and the second cavity 220 are cylindrical, the first cavity 210 and the second cavity 220 can be easily formed. In addition, the pressing pressure when forming the power generation element portion 52 and the reference electrode portion 152, and the stress due to the expansion and contraction during charging and discharging of the power generation element portion 52 and the reference electrode portion 152 can be evenly dispersed. Therefore, even at a higher pressure or stress, the exterior body 200 is less likely to be damaged, and the electrical characteristics of each electrode can be measured under a wider range of conditions. Note that the shapes of the first cavity 210 and the second cavity 220 are not limited to cylindrical shapes, and may be rectangular parallelepiped shapes or polygonal prism shapes. Also, the first cavity 210 and the second cavity 220 may be tapered.

[0145] The inner surface 210a of the exterior body 200 that forms the first cavity 210 is in contact with the power generation element portion 52, the positive electrode current collector 62, and the negative electrode current collector 72. That is, the inner surface 210a is in contact with the solid battery portion 102. The inner surface 220a of the exterior body 200 that forms the second cavity 220 is in contact with the reference electrode portion 152 and the reference electrode current collector 160.

[0146] Note that the positional relationship and shape between the first cavity 210 and the second cavity 220 may be any positional relationship and shape as long as the power generation element portion 52 and the reference electrode portion 152 can be in electrochemical contact. The positional relationship and shape between the first cavity 210 and the second cavity 220 may be set to any positional relationship and shape in view of the extraction of current from the positive electrode layer 12, the negative electrode layer 22, and the reference electrode 112, and the ease of processing.

[0147] The material of the exterior body 200 is not particularly limited as long as it is an insulating material. Examples of the material of the exterior body 200 include resin materials such as epoxy resin, polycarbonate resin, polybutadiene resin, acrylic resin, polyamide resin, and polyacetal resin, and ceramics. Among these, the portion of the exterior body 200 that is in contact with the power generation element portion 52 and the reference electrode portion 152 may contain a resin material as a main component from the viewpoints of workability, light weight, and cost.

[0148] (Embodiment 4) Next, the battery according to Embodiment 4 will be described.

[0149] The battery according to Embodiment 4 is mainly different from Embodiment 3 in that the exterior body has a two-layer structure. Hereinafter, the differences from Embodiments 1 to 3 will be mainly described, and the description of the common points will be omitted or simplified.

[0150] FIG. 5A is a top view showing a schematic configuration of a battery 503 according to the present embodiment. FIG. 5B is a cross-sectional view showing a schematic configuration of the battery 503 according to the present embodiment. FIG. 5B shows a cross-section of the battery 503 at the position indicated by the line Vb-Vb in FIG. 5A. The battery 503 includes an exterior body 203 instead of the exterior body 200 as compared with the battery 502 according to Embodiment 3. Since the external shapes of the exterior body 200 and the exterior body 203 are the same, the side surface of the battery 503 has the same shape as the battery 502 shown in FIG. 4C.

[0151] As shown in FIGS. 5A and 5B, the battery 503 includes a solid battery portion 102 including a power generation element portion 52, a reference electrode portion 152, a reference electrode current collector 160, and an exterior body 203 that covers the power generation element portion 52 and the reference electrode portion 152 and has a first cavity 213 and a second cavity 223.

[0152] The exterior body 203 has a first exterior body portion 230 and a second exterior body portion 240 located outside the first exterior body portion 230 when viewed from the first direction. The shapes of the first exterior body portion 230 and the second exterior body portion 240 are each columnar with a cavity formed inside.

[0153] The first cavity 213 is located at the center of the first exterior body part 230 as viewed from the first direction and is a hole penetrating the first exterior body part 230. The first cavity 213 is formed in the first exterior body part 230. The inner surface 213a of the first exterior body part 230 forming the first cavity 213 is in contact with the power generation element part 52, the positive electrode current collector 62, and the negative electrode current collector 72. That is, the inner surface 213a is in contact with the solid battery part 102.

[0154] Also, the second cavity 223 is located at the center of the second exterior body part 240 (exterior body 203) as viewed from the second direction and is a hole that reaches the first cavity 213 through the first exterior body part 230 from the outer surface of the second exterior body part 240. Among the inner surfaces 223a of the exterior body 203 forming the second cavity 223, the inner surface of the first exterior body part 230 is in contact with the reference electrode part 152. Among the inner surfaces 223a of the exterior body 203 forming the second cavity 223, the inner surface of the second exterior body part 240 is not in contact with the reference electrode part 152. Note that the inner surface of the second exterior body part 240 may be in contact with the reference electrode part 152.

[0155] The first exterior body part 230 is in contact with the power generation element part 52 and the reference electrode part 152. Specifically, the first exterior body part 230 is in contact with the side surfaces of the power generation element part 52 and the reference electrode part 152 respectively. The first exterior body part 230 is the part of the exterior body 203 that is in contact with the power generation element part 52 and the reference electrode part 152. Also, when viewed from the first direction, the outer surface of the first exterior body part 230 is entirely covered by the second exterior body part 240 and is in contact with the second exterior body part 240. Note that a part of the outer surface of the first exterior body part 230 when viewed from the first direction may not be covered by the second exterior body part 240.

[0156] As the material of the first exterior body part 230, the material of the above-described exterior body 200 can be used. The first exterior body part 230 may contain a resin material as a main component.

[0157] The second outer body portion 240 is in contact with the reference electrode current collector 160. Also, the second outer body portion 240 is not in contact with the power generation element portion 52 and the reference electrode portion 152. Note that the second outer body portion 240 may not be in contact with the reference electrode current collector 160. For example, another member may exist between the reference electrode current collector 160 and the second outer body portion 240. Also, the second outer body portion 240 may be in contact with the reference electrode portion 152.

[0158] Also, the inner surface of the second outer body portion 240 when viewed from the first direction is in contact with the first outer body portion 230. The second outer body portion 240 is a cylinder having a cylindrical cavity that houses the first outer body portion 230 at the central portion when viewed from the first direction. The strength of the second outer body portion 240 is higher than the strength of the first outer body portion 230. Thereby, even when a high pressure is applied to the power generation element portion 52, since the first outer body portion 230 is covered with the second outer body portion 240 having high strength, deformation and breakage of the first outer body portion 230 are suppressed, and the power generation element portion 52 can be appropriately formed. Also, the pressurized state of the power generation element portion 52 can be maintained at a higher pressure. Therefore, the electrical characteristics of each electrode of the battery 503 can be stably measured. Also, since the outer body 203 has the second outer body portion 240, an outer body having the same level of strength can be realized even if the portion covering the power generation element portion 52 is thin as compared with the case where the outer body is constituted only by the first outer body portion 230, so miniaturization is possible. Note that the second outer body portion 240 may cover the outside of the first outer body portion 230 when viewed from the second direction. In this case, higher pressurization becomes possible by the reference electrode portion 152.

[0159] The material of the second outer body portion 240 may be a material having higher strength than the first outer body portion 230. Examples of the material of the second outer body portion 240 include metal materials such as iron, copper, nickel, and aluminum, alloys combining them, and alloys mainly composed of them, high-strength resins such as engineering plastics, and resin composite materials reinforced with carbon fibers or the like. The second outer body portion 240 may contain a metal material as a main component from the viewpoints of strength and workability. Also, stainless steel may be used for the second outer body portion 240 from the viewpoint of corrosion resistance.

[0160] (Example) Examples of the present disclosure are shown below. These examples are for illustrative purposes only and do not limit the present disclosure.

[0161] First, a glass electrolyte powder of sulfide solid electrolyte Li2S-P2S5 (Li2S:P2S5 = 70:30 (molar ratio)) was prepared as a raw material for the solid electrolyte. A powder having triclinic crystals as the main component, a wide crystallinity distribution from crystalline to amorphous, and an average particle size of 5 μm, obtained by annealing this glass electrolyte powder at 200 °C, was used as the solid electrolyte.

[0162] Next, LiNi 0.85 Co 0.15 Al 0.05 O2 powder and the solid electrolyte were mixed in a volume ratio of 1:1 to obtain a positive electrode mixture.

[0163] Also, natural graphite powder and the solid electrolyte were mixed in a volume ratio of 1:1 to obtain a negative electrode mixture as the negative electrode active material.

[0164] Next, a first exterior body part made of acrylic resin, which is cylindrical with a diameter of 20 mm and a height of 20 mm and has a first cavity with a diameter of 9.5 mm formed at its center, and a second exterior body part made of stainless steel, which is cylindrical with a diameter of 30 mm and a height of 20 mm and has a cavity for accommodating the first exterior body part with a diameter of 20 mm at its center, were used to form an exterior body. An exterior body was prepared in which a second cavity with a diameter of 3 mm connected to the first cavity was formed at the central portion of the side surface of the exterior body. Then, 30 mg of solid electrolyte was placed in the second cavity, and after pressing the solid electrolyte to form a second solid electrolyte layer, metallic lithium was placed as a reference electrode in contact with the second solid electrolyte layer to fabricate a reference electrode part. Also, 80 mg of solid electrolyte was placed in the first cavity, and after pressing the solid electrolyte at 100 MPa to form a first solid electrolyte layer, 16.7 mg of a positive electrode mixture was placed on one side surface thereof, and the positive electrode mixture was pressed at 100 MPa to fabricate a positive electrode layer. Subsequently, 15.4 mg of a negative electrode mixture was placed on the side opposite to the positive electrode layer side of the first solid electrolyte layer, and the negative electrode mixture was pressed at 600 MPa to form a negative electrode layer, thereby fabricating a power generation element part. Also, the power generation element part was formed such that the side surface of the power generation element part was in contact with the second solid electrolyte layer. Thereby, a battery including the power generation element part and the reference electrode part was obtained. Note that a jig for pressing was used during the pressing of each layer.

[0165] Next, a stainless steel rod having a cylindrical shape with a diameter of 9.5 mm was inserted from the vertical direction of the first cavity, and used as a positive electrode current collector and a negative electrode current collector, respectively. Also, a stainless steel rod with a diameter of 3 mm was inserted into the second cavity and used as a reference electrode current collector.

[0166] Next, from the vertical direction of the stainless steel rods that are the positive electrode current collector and the negative electrode current collector, pressure was applied with bolts to achieve a pressure of 150 MPa and the pressurized state was maintained, thereby obtaining the battery in the example. Hereinafter, the positive electrode layer and the positive electrode current collector are collectively referred to as the positive electrode, the negative electrode layer and the negative electrode current collector are collectively referred to as the negative electrode, and the reference electrode and the reference electrode current collector are collectively referred to as the reference electrode.

[0167] After connecting voltage measuring devices between the positive electrode and the negative electrode, between the positive electrode and the reference electrode, and between the negative electrode and the reference electrode of the obtained evaluation battery, a current of 120 μA was passed between the positive electrode and the negative electrode, and the battery was charged up to 4.2 V. Then, discharging was performed up to 2.5 V at the same current value. FIG. 6 is a diagram showing the results of voltage measurement when the battery in the example was charged and discharged.

[0168] As shown in FIG. 6, in the battery in the example, the battery voltage, which is the voltage between the positive electrode and the negative electrode during charging, increased, and the battery voltage decreased during discharging, confirming that the battery could be charged and discharged. Also, during charging and discharging, the positive electrode potential (vs. Li) and the negative electrode potential (vs. Li) also showed behaviors corresponding to the battery voltage, confirming that the positive electrode potential and the negative electrode potential could be measured simultaneously with the battery voltage.

[0169] (Other embodiments) As described above, the battery, the exterior body, and the method for measuring the electrical characteristics of the battery according to the present disclosure have been described based on the embodiments. However, the present disclosure is not limited to these embodiments. Without departing from the gist of the present disclosure, various modifications conceived by those skilled in the art applied to the embodiments, or other forms constructed by combining some components in the embodiments are also included in the scope of the present disclosure.

[0170] In the above embodiment, the power generation element part includes a positive electrode layer and a negative electrode layer, but is not limited thereto. For example, when the battery is used to grasp the electrical characteristics of the electrodes, the power generation element part may include a second positive electrode layer instead of the negative electrode layer. In this case, the electrical characteristics of any of the positive electrode layers can be measured independently. Also, the power generation element part may include a second negative electrode layer instead of the positive electrode layer.

[0171] Also, various changes, replacements, additions, omissions, etc. can be made within the scope of the claims or their equivalents in the above embodiment.

Industrial applicability

[0172] According to the present disclosure, a battery capable of easily measuring the potential of a positive electrode and / or a negative electrode can be obtained. Further, an exterior body capable of easily forming and holding a battery can be obtained.

Explanation of Signs

[0173] 10, 12 Positive electrode layer 20, 22 Negative electrode layer 30, 32 First solid electrolyte layer 50, 52 Power generation element part 50a, 52a Side surface 60, 62 Positive electrode current collector 70, 72 Negative electrode current collector 91, 92, 93 Voltage measuring device 100, 101, 102 Solid battery part 110, 112 Reference electrode 130, 132 Second solid electrolyte layer 130a, 132a First main surface 130b, 132b Second main surface 150, 152 Reference electrode part 160 Reference electrode current collector 200, 203 Exterior body 210, 213 First cavity 210a, 213a, 220a, 223a Inner surface 220, 223 Second cavity 230 First exterior body part 240 Second exterior body part 500, 501, 502, 503 Battery

Claims

1. A power generation element unit having a first electrode layer, a second electrode layer, and a first solid electrolyte layer positioned between the first electrode layer and the second electrode layer, a second solid electrolyte layer having a first main surface in contact with a side surface of the power generation element unit and a second main surface opposite to the first main surface, and a reference electrode unit having a reference electrode in contact with the second main surface of the second solid electrolyte layer, in the stacking direction of the power generation element unit, the length of the first main surface is longer than the length of the side surface, a battery.

2. The first solid electrolyte layer and the second solid electrolyte layer have lithium ion conductivity, The battery according to claim 1.

3. The reference electrode contains at least one of metallic lithium, a lithium alloy, and a lithium compound, The battery according to claim 1 or 2.

4. Comprising a plurality of the stacked power generation element units, The battery according to any one of claims 1 to 3.

5. The first main surface is in contact with a plurality of the power generation element units, The battery according to claim 4.

6. Further comprising an exterior body covering the power generation element unit and the reference electrode unit, The battery according to any one of claims 1 to 5.

7. The exterior body has a first cavity extending in a first direction and a second cavity extending in a second direction intersecting the first direction and connected to the first cavity, The power generation element unit is in contact with an inner surface of the exterior body forming the first cavity, The reference electrode unit is in contact with an inner surface of the exterior body forming the second cavity, The battery according to claim 6.

8. The shape of at least one of the first cavity and the second cavity is cylindrical, The battery according to claim 7.

9. In the exterior body, a portion in contact with the power generation element unit and the reference electrode unit contains a resin material, The battery according to claim 7 or 8.

10. The exterior body has a first exterior body portion in contact with the power generation element unit and the reference electrode unit and a second exterior body portion located outside the first exterior body portion, The strength of the second exterior body portion is higher than the strength of the first exterior body portion, The battery according to any one of claims 7 to 9.

11. The second exterior body portion contains a metallic material, The battery according to claim 10.

12. A current path is provided between at least one of the first electrode layer or the second electrode layer and the reference electrode, The battery according to any one of claims 1 to 11.

13. An exterior body according to any one of claims 6 to 12, An exterior body for a battery.

14. A method for measuring the electrical characteristics of a battery including a power generation element unit having a first electrode layer, a second electrode layer, and a first solid electrolyte layer positioned between the first electrode layer and the second electrode layer, preparing a second solid electrolyte layer having a first main surface and a second main surface opposite to the first main surface, and a reference electrode portion having a reference electrode in contact with the second main surface, bringing the first main surface of the second solid electrolyte layer into contact with a side surface of the power generation element unit, measuring the electrical characteristics between at least one of the first electrode layer and the second electrode layer and the reference electrode, in the stacking direction of the power generation element unit, the length of the first main surface is longer than the length of the side surface, measurement method.

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