Manufacturing method of stacked battery

Abstract

This laminated battery production method is for producing a laminated battery in which a plurality of unit battery cells each having a negative electrode layer, a positive electrode layer, and a solid electrolyte layer positioned between the negative electrode layer and the positive electrode layer, are laminated. The method includes: a lamination step for laminating the plurality of unit battery cells; and a collective compression step for compressing, in the lamination direction, the plurality of unit battery cells laminated in the lamination step. In the lamination step, the plurality of unit battery cells are laminated in a disposition such that both of two unit battery cells that are positioned at lamination-directional both ends of the laminated plurality of unit battery cells have a lower compression degree than that of unit battery cells positioned between the two unit battery cells.

Description

[Technical field]

[0001] The present disclosure relates to a method for manufacturing a stacked battery. [Background technology]

[0002] Patent Document 1 discloses that from the start of charging until a preset intermediate SOC (State of Charge) value is reached, the battery assembly is charged without applying a restraint load in the stacking direction of the positive and negative electrodes, and then from the intermediate SOC value to the target SOC value, a restraint load is applied to the battery assembly in the stacking direction.

[0003] Patent Document 2 discloses a structure in which a solid-state battery includes a laminate including at least one unit cell including a positive electrode layer including a positive electrode active material, a negative electrode layer including a negative electrode active material, and a solid electrolyte layer laminated between the positive electrode layer and the negative electrode layer, and an exterior body that houses the laminate, the laminate includes a pressure-receiving portion provided on at least a part of the periphery of the exterior body, and the pressure-receiving portion has a thickness that is less than the total thickness of the laminate and the exterior body in the stacking direction of the unit cell.

[0004] Patent Document 3 discloses that in a secondary battery in which a positive electrode and a negative electrode are stacked with a separator containing an electrolyte interposed between them, the electrode layer of one of the positive and negative electrode plates is formed to have a lower density than the electrode layer of the other electrode plate. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2017-111940 A [Patent Document 2] JP 2015-179566 A [Patent Document 3] JP 2010-232011 A Summary of the Invention [Problem to be solved by the invention]

[0006] In the prior art, further improvement in the reliability of batteries is desired. In stacked batteries, in particular, improvement in reliability is desired because the battery capacity and / or voltage increases.

[0007] Therefore, the present disclosure provides a method for manufacturing a stacked battery with improved reliability. [Means for solving the problem]

[0008] A manufacturing method for a stacked battery in one aspect of the present disclosure is a manufacturing method for a stacked battery in which a plurality of unit battery cells are stacked, each unit battery cell having a negative electrode layer, a positive electrode layer, and a solid electrolyte layer located between the negative electrode layer and the positive electrode layer, the manufacturing method including a stacking step of stacking the plurality of unit battery cells, and a collective compression step of compressing the plurality of unit battery cells stacked in the stacking step in a stacking direction, wherein the plurality of unit battery cells are stacked in the stacking step in an arrangement such that the degree of compression of two unit battery cells located at both ends in the stacking direction is lower than the degree of compression of a unit battery cell located between the two unit battery cells. Effect of the Invention

[0009] According to the present disclosure, the reliability of a stacked battery can be improved. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a cross-sectional view showing a schematic configuration of a stacked battery according to an embodiment. [Diagram 2] FIG. 2 is a cross-sectional view showing a schematic configuration of a laminated battery including a sealing member according to an embodiment. [Diagram 3] FIG. 3 is a cross-sectional view showing a schematic configuration of a stacked battery according to a modified example of the embodiment. [Figure 4] FIG. 4 is a cross-sectional view showing a schematic configuration of a laminated battery including a sealing member according to a modified example of the embodiment. [Diagram 5]FIG. 5 is a flowchart illustrating a method for manufacturing a stacked battery according to an embodiment. [Figure 6A] FIG. 6A is a cross-sectional view illustrating an example of a layered structure of a laminate formed in a laminate forming step according to an embodiment. [Figure 6B] FIG. 6B is a cross-sectional view illustrating an example of a layered structure of the laminate formed in the laminate forming step according to the embodiment. [Figure 6C] FIG. 6C is a cross-sectional view illustrating an example of a layered structure of the laminate formed in the laminate forming step according to the embodiment. [Figure 6D] FIG. 6D is a cross-sectional view illustrating an example of a layered structure of the laminate formed in the laminate forming step according to the embodiment. [Figure 6E] FIG. 6E is a cross-sectional view illustrating an example of a layered structure of a laminate formed in a laminate forming step according to the embodiment. [Figure 6F] FIG. 6F is a cross-sectional view illustrating an example of a layered structure of the laminate formed in the laminate forming step according to the embodiment. [Figure 6G] FIG. 6G is a cross-sectional view illustrating an example of a layered structure of the laminate formed in the laminate forming step according to the embodiment. [Figure 6H] FIG. 6H is a cross-sectional view illustrating an example of a layered structure of the laminate formed in the laminate forming step according to the embodiment. [Figure 7A] FIG. 7A is a cross-sectional view showing an example of a stacked configuration of unit battery cells formed in an individual compression step according to an embodiment. [Figure 7B] FIG. 7B is a cross-sectional view showing an example of a stacked configuration of unit battery cells formed in an individual compression step according to the embodiment. [Figure 7C] FIG. 7C is a cross-sectional view showing an example of a stacked configuration of unit battery cells formed in an individual compression step according to the embodiment. [Figure 8] FIG. 8 is a diagram illustrating an example of adjustment of the degree of compression of unit battery cells in the individual compression step according to the embodiment. [Figure 9] FIG. 9 is a schematic diagram showing the relationship between the charged electric quantity and the voltage at the initial stage of charging of a unit battery cell in the embodiment. [Figure 10] FIG. 10 is a diagram for explaining the lamination step and the collective compression step in the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] (How one aspect of the present disclosure was achieved) In a stacked battery, it is important that the battery capacities of the unit battery cells that make up the stacked battery are uniform. Variations in the battery capacities of the unit battery cells can easily lead to overcharging and overdischarging in a series-connected stacked battery, and can easily cause variations in the current values ​​of the electrode current collector leads in a parallel-connected stacked battery, reducing the reliability of the battery.

[0012] Therefore, the present disclosure provides a manufacturing method for a stacked battery and a stacked battery with improved reliability.

[0013] (Summary of the Disclosure) A manufacturing method for a stacked battery in one embodiment of the present disclosure is a manufacturing method for a stacked battery in which a plurality of unit battery cells are stacked, each unit battery cell having a negative electrode layer, a positive electrode layer, and a solid electrolyte layer located between the negative electrode layer and the positive electrode layer, the manufacturing method including a stacking process of stacking the plurality of unit battery cells, and a collective compression process of compressing the plurality of unit battery cells stacked in the stacking process in a stacking direction, wherein the plurality of unit battery cells are stacked in the stacking process in an arrangement such that the degree of compression of two unit battery cells located at both ends in the stacking direction is lower than the degree of compression of a unit battery cell located between the two unit battery cells.

[0014] As a result, in the stacking step, the multiple unit battery cells are stacked such that the unit battery cells at both ends in the stacking direction are less compressed than the unit battery cells at the center in the stacking direction. Also, in the collective compression step, the pressure that compresses the unit battery cells at both ends in the stacking direction and that are relatively less compressed acts relatively strongly, and the pressure that compresses the unit battery cells at the center in the stacking direction and that are relatively more compressed acts relatively weakly. By stacking the unit battery cells with different degrees of compression in the above arrangement, it is possible to cancel out the variation in the degree of compression of the unit battery cells caused by the strength of the compressive pressure in the collective compression step. Therefore, it is possible to reduce the variation in the degree of compression of the multiple unit battery cells formed after the collective compression step. Also, as the compression bonding of the unit battery cells progresses and the degree of compression becomes higher, the battery capacity also becomes higher. Therefore, by reducing the variation in the degree of compression of the multiple unit battery cells, it is possible to reduce the variation in the battery capacity of the unit battery cells.

[0015] As a result, when a series-connected stacked battery is manufactured, it is possible to suppress overcharging and overdischarging of each of the multiple unit battery cells. Also, when a parallel-connected stacked battery is manufactured, it is possible to reduce the variation in current flowing through the current collecting leads that draw current from the electrodes, thereby suppressing localized heat generation in the unit battery cells due to overheating caused by the flow of excessive current. Therefore, the manufacturing method for a stacked battery according to this embodiment can suppress unsafe events such as deterioration and heat generation of the unit battery cells, and can manufacture a stacked battery with improved reliability.

[0016] Furthermore, for example, the method may further include an individual compression step, prior to the stacking step, of compressing a stack in which the positive electrode layer, the negative electrode layer, and the solid electrolyte layer are stacked in a stacking direction to form each of the plurality of unit battery cells to be stacked in the stacking step.

[0017] This makes it possible to form a plurality of unit battery cells to be stacked in the stacking step according to the characteristics of the stacked battery to be manufactured.

[0018] Also, for example, the method may further include a measurement process for measuring characteristics of each of the plurality of unit battery cells, and in the individual compression process, the degree of compression of each of the plurality of unit battery cells to be stacked in the stacking process may be adjusted based on the characteristics measured in the measurement process.

[0019] This makes it possible to adjust the degree of compression of the multiple unit battery cells formed in the individual compression process based on the characteristics measured in the measurement process so as to reduce variation in the degree of compression of the multiple unit battery cells that make up the manufactured stacked battery, thereby further reducing variation in the battery capacity of the multiple unit battery cells.

[0020] Furthermore, for example, in the measuring step, electrical characteristics of each of the plurality of unit battery cells may be measured as the characteristics.

[0021] In a unit battery cell in which an anode layer, a cathode layer, and a solid electrolyte layer are stacked, the higher the degree of compression, the higher the battery capacity, and therefore the electrical characteristics change. Therefore, by measuring the electrical characteristics of the unit battery cell in the measurement process, the battery capacity and the degree of compression of the unit battery cell can be estimated.

[0022] Furthermore, for example, in the measuring step, charge / discharge characteristics of each of the plurality of unit battery cells may be measured as the electrical characteristics.

[0023] In this way, the charge / discharge characteristics are measured to measure the electrical quantity and voltage related to the battery capacity, so that the battery capacity and the degree of compression of the unit battery cell can be estimated with high accuracy.

[0024] Also, for example, in the measuring step, the charge / discharge characteristics may be measured in a range of 10% or less of the battery capacity of the plurality of unit battery cells.

[0025] As a result, the charge / discharge characteristics are measured in a partial region of the battery capacity of the unit battery cell, so the measurement time for the charge / discharge characteristics can be shortened compared to the case of full charge. Furthermore, since the amount of increase in the voltage of the unit battery cell relative to the amount of charged electricity at the beginning of charging is correlated with the battery capacity, the battery capacity and degree of compression of the unit battery cell can be estimated even from the charge / discharge characteristics measured in a partial region of the battery capacity. This allows the stacked battery to be manufactured with high productivity. Furthermore, since the amount of electricity charged is small, even if the negative electrode layer and the positive electrode layer come into contact with each other during manufacturing to cause a short circuit, the amount of current flowing is small and heat generation, etc. is suppressed. This allows the safety of the stacked battery to be improved during manufacturing.

[0026] For example, the measurement time for the charge / discharge characteristics may be one minute or less.

[0027] As a result, even if the measurement time for the charge / discharge characteristics is short, the increase in voltage of the unit battery cell relative to the amount of charged electricity at the beginning of charging correlates with the battery capacity, so the battery capacity and degree of compression of the unit battery cell can be estimated, thereby enabling stacked batteries to be manufactured with high productivity.

[0028] Furthermore, for example, in the measuring step, impedance of each of the plurality of unit battery cells may be measured as the electrical characteristic.

[0029] As a result, since the impedance of a unit battery cell is correlated with the battery capacity, the battery capacity and degree of compression of the unit battery cell can be estimated simply by measuring the impedance of the unit battery cell, thereby enabling stacked batteries to be manufactured with high productivity.

[0030] Furthermore, for example, in the measuring step, mechanical characteristics of each of the plurality of unit battery cells may be measured as the characteristics.

[0031] By measuring such mechanical properties, the degree of compression of the unit battery cell can be directly confirmed.

[0032] Furthermore, for example, in the measuring step, the amount of mechanical deformation of each of the plurality of unit battery cells may be measured as the mechanical characteristic using a contact displacement gauge, an optical displacement gauge, or a gap gauge.

[0033] This makes it possible to measure the mechanical properties of the unit battery cells while compressing them, shortening the process time and enabling stacked batteries to be manufactured with high productivity.

[0034] Also, for example, in the stacking process, the multiple unit battery cells may be stacked in an arrangement such that the degree of compression of one of the multiple unit battery cells located at the end side in the stacking direction is equal to or less than the degree of compression of the other unit battery cell.

[0035] As a result, the compressive pressure in the bulk compression process becomes stronger from the center to both ends in the stacking direction, but the unit battery cells are stacked in an arrangement in which the degree of compression of the unit battery cells decreases from the center to both ends in the stacking direction to offset the increased degree of compression caused by this pressure. This makes it possible to further reduce variation in the degree of compression of the unit battery cells after the bulk compression process.

[0036] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

[0037] The embodiments described below are all comprehensive or specific examples. The numerical values, shapes, materials, components, component arrangements and connection forms, steps, and order of steps shown in the following embodiments are merely examples and are not intended to limit the present disclosure. In addition, among the components in the following embodiments, components that are not described in the independent claims are described as optional components.

[0038] In addition, each figure is a schematic diagram and is not necessarily illustrated precisely. Therefore, for example, the scales in each figure do not necessarily match. In addition, in each figure, substantially the same configurations are given the same reference numerals, and duplicated explanations are omitted or simplified.

[0039] Furthermore, in this specification, terms indicating the relationship between elements, such as "parallel," terms indicating the shape of an element, such as "rectangle," and numerical ranges are not expressions that only express a strict meaning, but are expressions that include a substantially equivalent range, for example, a difference of about a few percent.

[0040] In this specification and the drawings, the x-axis, y-axis, and z-axis represent the three axes of a three-dimensional Cartesian coordinate system. In each embodiment, the z-axis direction is the thickness direction of the battery. 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. In this specification, the "thickness direction" refers to the direction along the stacking direction in the stacked battery and unit battery cells, in other words, the direction perpendicular to the main surface of each layer.

[0041] In addition, in this specification, the term "planar view" refers to the case where the stacked battery and unit battery cells are viewed along the thickness direction.

[0042] In this specification, the negative electrode current collector and the positive electrode current collector may be collectively referred to simply as "current collectors", and the negative electrode active material layer and the positive electrode active material layer may be collectively referred to simply as "active material layers".

[0043] (Embodiment 1) First, the configuration of the stacked battery according to this embodiment will be described.

[0044] FIG. 1 is a cross-sectional view showing a schematic configuration of a stacked battery 1000 according to the present embodiment.

[0045] As shown in Fig. 1, the stacked battery 1000 in this embodiment includes a plurality of unit battery cells 2000. Specifically, the stacked battery 1000 has a structure in which a plurality of unit battery cells 2000 are stacked. The plurality of unit battery cells 2000 are electrically connected in series to form the stacked battery 1000. The stacked battery 1000 is, for example, a secondary battery that can be repeatedly charged and discharged.

[0046] Each unit battery cell 2000 has an anode layer 100, a cathode layer 200, and a solid electrolyte layer 300 located between the anode layer 100 and the cathode layer 200. The multiple unit battery cells 2000 are stacked so that the electrodes face in the same direction. That is, in the stacked battery 1000, adjacent unit battery cells 2000 are stacked so that the anode layer 100 of one unit battery cell 2000 and the cathode layer 200 of the other unit battery cell 2000 are adjacent to each other. This makes the stacked battery 1000 a series-connected stacked battery in which the multiple unit battery cells 2000 are electrically connected in series.

[0047] The negative electrode layer 100 and the positive electrode layer 200 face each other via the solid electrolyte layer 300. In the illustrated example, the unit battery cell 2000 has a pair of the negative electrode layer 100 and the positive electrode layer 200 facing each other via the solid electrolyte layer 300, but is not limited thereto, and the unit battery cell 2000 may have two or more of at least any one of the negative electrode layer 100, the positive electrode layer 200, and the solid electrolyte layer 300.

[0048] In each unit battery cell 2000, the anode layer 100, the solid electrolyte layer 300, and the cathode layer 200 are stacked in this order along the thickness direction (z-axis direction) of the unit battery cell 2000. More specifically, in each unit battery cell 2000, the anode current collector 120, the anode active material layer 110, the solid electrolyte layer 300, the cathode active material layer 210, and the cathode current collector 220 are stacked in this order along the thickness direction of the unit battery cell 2000.

[0049] The negative electrode layer 100 includes a negative electrode active material layer 110 and a negative electrode current collector 120. The negative electrode active material layer 110 is located between a solid electrolyte layer 300 and the negative electrode current collector 120. The thickness of the negative electrode active material layer 110 is, for example, not limited to, 5 μm or more and 300 μm or less.

[0050] The negative electrode active material layer 110 includes, for example, a negative electrode active material as an electrode material. As the negative electrode active material contained in the negative electrode active material layer 110, for example, a negative electrode active material such as graphite or metallic lithium can be used. As the material of the negative electrode active material, various materials capable of extracting and inserting ions such as lithium (Li) or magnesium (Mg) can be used.

[0051] The material contained in the negative electrode active material layer 110 may be, for example, a solid electrolyte such as an inorganic solid electrolyte. The inorganic solid electrolyte may be, for example, a sulfide solid electrolyte or an oxide solid electrolyte. The sulfide solid electrolyte may be, for example, a mixture of lithium sulfide (Li2S) and diphosphorus pentasulfide (P2S5). The material contained in the negative electrode active material layer 110 may be, for example, a conductive agent such as acetylene black, carbon black, graphite, or carbon fiber, or a binding binder such as polyvinylidene fluoride.

[0052] The negative electrode current collector 120 is in contact with the negative electrode active material layer 110. The thickness of the negative electrode current collector 120 is, for example, 5 μm to 100 μm, but is not limited thereto. The negative electrode current collector 120 is a member having electrical conductivity. The negative electrode current collector 120 may be, for example, a thin film having electrical conductivity. As a material constituting the negative electrode current collector 120, for example, metals such as stainless steel (SUS), aluminum (Al), copper (Cu), and nickel (Ni) can be used. Specifically, as the negative electrode current collector 120, for example, metal foils such as SUS foil, Cu foil, and Ni foil can be used.

[0053] Note that another layer such as a bonding layer made of a conductive material may be provided between the negative electrode active material layer 110 and the negative electrode current collector 120. The negative electrode layer 100 does not need to include the negative electrode current collector 120. For example, a current collector of an adjacent unit battery cell 2000, an electrode for extraction, or a substrate supporting the stacked battery 1000 may function as a current collector for the negative electrode active material layer 110. In other words, the negative electrode layer 100 may include only the negative electrode active material layer 110 out of the negative electrode active material layer 110 and the negative electrode current collector 120.

[0054] The positive electrode layer 200 includes a positive electrode active material layer 210 and a positive electrode current collector 220. The positive electrode active material layer 210 is located between the solid electrolyte layer 300 and the positive electrode current collector 220. The thickness of the positive electrode active material layer 210 is, for example, not less than 5 μm and not more than 300 μm, but is not limited to this.

[0055] The positive electrode active material layer 210 contains, for example, a positive electrode active material as an electrode material. The positive electrode active material is a material that constitutes a counter electrode to the negative electrode active material.

[0056] Examples of the positive electrode active material contained in the positive electrode active material layer 210 that can be used include lithium cobalt oxide composite oxide (LCO), lithium nickel oxide composite oxide (LNO), lithium manganese oxide composite oxide (LMO), lithium-manganese-nickel composite oxide (LMNO), lithium-manganese-cobalt composite oxide (LMCO), lithium-nickel-cobalt composite oxide (LNCO), and lithium-nickel-manganese-cobalt composite oxide (LNMCO).

[0057] As the positive electrode active material, various materials capable of extracting and inserting ions such as Li or Mg ions can be used.

[0058] The material contained in the positive electrode active material layer 210 may be, for example, a solid electrolyte such as an inorganic solid electrolyte. The inorganic solid electrolyte may be, for example, a sulfide solid electrolyte or an oxide solid electrolyte. The sulfide solid electrolyte may be, for example, a mixture of lithium sulfide (Li2S) and diphosphorus pentasulfide (P2S5). The surface of the positive electrode active material may be coated with a solid electrolyte. The material contained in the positive electrode active material layer 210 may be, for example, a conductive agent such as acetylene black, carbon black, graphite, or carbon fiber, or a binding binder such as polyvinylidene fluoride.

[0059] The positive electrode current collector 220 is in contact with the positive electrode active material layer 210. The thickness of the positive electrode current collector 220 is, for example, 5 μm to 100 μm, but is not limited thereto. The positive electrode current collector 220 is a member having electrical conductivity. The positive electrode current collector 220 may be, for example, a thin film having electrical conductivity. As a material constituting the negative electrode current collector 120, for example, metals such as stainless steel (SUS), aluminum (Al), copper (Cu), and nickel (Ni) can be used. Specifically, as the positive electrode current collector 220, for example, metal foils such as SUS foil, Cu foil, and Ni foil can be used.

[0060] Note that another layer such as a bonding layer made of a conductive material may be provided between the positive electrode active material layer 210 and the positive electrode current collector 220. The positive electrode layer 200 does not need to include the positive electrode current collector 220. For example, a current collector of an adjacent unit battery cell 2000, an electrode for extraction, or a substrate supporting the stacked battery 1000 may function as a current collector for the positive electrode active material layer 210. In other words, the positive electrode layer 200 may include only the positive electrode active material layer 210 out of the positive electrode active material layer 210 and the positive electrode current collector 220.

[0061] The solid electrolyte layer 300 is disposed between the negative electrode active material layer 110 and the positive electrode active material layer 210. The solid electrolyte layer 300 is in contact with both the negative electrode active material layer 110 and the positive electrode active material layer 210. The thickness of the solid electrolyte layer 300 may be 5 μm or more and 300 μm or less, or may be 5 μm or more and 100 μm or less.

[0062] In this embodiment, the negative electrode active material layer 110, the positive electrode active material layer 210, and the solid electrolyte layer 300 are maintained in a parallel plate shape. This makes it possible to suppress the occurrence of cracking or collapse due to bending. The negative electrode active material layer 110, the positive electrode active material layer 210, and the solid electrolyte layer 300 may be smoothly curved together.

[0063] The solid electrolyte layer 300 is a layer containing an electrolyte material. As the electrolyte material, a generally known electrolyte for batteries can be used. The solid electrolyte layer 300 contains a solid electrolyte as an electrolyte. The unit battery cell 2000 may be, for example, an all-solid-state battery.

[0064] As the solid electrolyte, for example, a solid electrolyte such as an inorganic solid electrolyte can be used. As the inorganic solid electrolyte, a sulfide solid electrolyte or an oxide solid electrolyte can be used. As the sulfide solid electrolyte, for example, a mixture of lithium sulfide (Li2S) and diphosphorus pentasulfide (P2S5) can be used. In addition to the electrolyte material, the solid electrolyte layer 300 may contain a binder such as polyvinylidene fluoride.

[0065] 1 are manufactured so as to reduce variations in the degree of compression and battery capacity of the unit battery cells 2000. A manufacturing method for reducing variations in the degree of compression and battery capacity will be described later.

[0066] In the stacked battery 1000, the same amount of current flows through each of the multiple unit battery cells 2000 electrically connected in series. Therefore, if there is variation in the battery capacity of each of the multiple unit battery cells 2000, the unit battery cells 2000 will be overcharged and overdischarged. In contrast, in the stacked battery 1000 of the present embodiment, there is little variation in the battery capacity of each of the multiple unit battery cells 2000. This makes it possible to prevent overcharging, overdischarging, and the like of the unit battery cells 2000 in the stacked battery 1000. As a result, it is possible to prevent unsafe events such as deterioration and heat generation of the unit battery cells 2000. This increases the reliability of the stacked battery 1000.

[0067] The laminated battery according to this embodiment may further include a sealing member. Fig. 2 is a cross-sectional view showing a schematic configuration of a laminated battery 1000A including a sealing member 700 according to this embodiment. As shown in Fig. 2, the laminated battery 1000A includes the sealing member 700, a negative electrode current collector lead 320, and a positive electrode current collector lead 330 in addition to the configuration of the laminated battery 1000 described above.

[0068] The negative electrode current collector lead 320 and the positive electrode current collector lead 330 are connected to the negative electrode current collector 120 and the positive electrode current collector 220, respectively, of the unit battery cells 2000 at both ends in the stacking direction, and are terminals for extracting current from the stacked battery 1000A. Examples of materials that can be used to form the negative electrode current collector lead 320 and the positive electrode current collector lead 330 include metals such as nickel, stainless steel, aluminum, and copper.

[0069] The sealing member 700 is disposed so as to cover all of the stacked unit battery cells 2000. A portion of the negative electrode current collector lead 320 and the positive electrode current collector lead 330 is exposed and not covered by the sealing member 700. The sealing member 700 is formed, for example, using an electrically insulating material.

[0070] For example, the sealing member 700 is a member containing a first material. The sealing member 700 may be, for example, a member containing the first material as a main component. The sealing member 700 may be, for example, a member made of only the first material.

[0071] The first material may be, for example, a commonly known material for sealing members of batteries, such as a sealant. The first material may be, for example, a resin material. The first material may be an insulating material that does not have ion conductivity. For example, the first material may be at least one of an epoxy resin, an acrylic resin, a polyimide resin, and a silsesquioxane.

[0072] The sealing member 700 may contain a particulate metal oxide material. Examples of the metal oxide material that may be used include silicon oxide, aluminum oxide, titanium oxide, zinc oxide, cerium oxide, iron oxide, tungsten oxide, zirconium oxide, calcium oxide, zeolite, and glass. For example, the sealing member 700 may be formed using a resin material in which a plurality of particles made of a metal oxide material are dispersed.

[0073] By providing the sealing member 700, the reliability of the stacked battery 1000A can be improved in various respects, such as mechanical strength, short-circuit prevention, and moisture resistance.

[0074] [Variations] Next, a modified example of the embodiment will be described. In the following description, the differences from the above embodiment will be mainly described, and the description of the commonalities will be omitted or simplified as appropriate.

[0075] 3 is a cross-sectional view showing a schematic configuration of a stacked battery 1100 in this modified example, which differs from the stacked battery 1000 of the embodiment in that a plurality of unit battery cells 2000 are electrically connected in parallel.

[0076] 3, the stacked battery 1100 in this modification includes a plurality of unit battery cells 2000. Specifically, the stacked battery 1100 has a structure in which a plurality of unit battery cells 2000 are stacked. The plurality of unit battery cells 2000 are electrically connected in parallel to form the stacked battery 1100. The stacked battery 1100 also includes a negative electrode current collector lead 340 and a positive electrode current collector lead 350.

[0077] Among the multiple unit battery cells 2000, adjacent unit battery cells 2000 are stacked with the electrode orientation reversed. That is, in the stacked battery 1100, the multiple unit battery cells 2000 are stacked such that the negative electrode layers 100 or the positive electrode layers 200 of two adjacent unit battery cells 2000 are adjacent to each other. This makes the stacked battery 1100 a parallel-connected stacked battery in which the multiple unit battery cells 2000 are electrically connected in parallel.

[0078] In each unit battery cell 2000, the negative electrode layer 100, the solid electrolyte layer 300, and the positive electrode layer 200 are alternately stacked in this order and in reverse order along the thickness direction (z-axis direction) of the unit battery cell 2000.

[0079] The negative electrode current collector lead 340 and the positive electrode current collector lead 350 are conductors used for charging / discharging, monitoring the voltage between the terminals, etc. The negative electrode current collector lead 340 is electrically connected to the negative electrode current collector 120 of the negative electrode layer 100 of each of the multiple unit battery cells 2000. The positive electrode current collector lead 350 is electrically connected to the positive electrode current collector 220 of the positive electrode layer 200 of each of the multiple unit battery cells 2000.

[0080] 3 is manufactured so as to reduce variations in the degree of compression and battery capacity of the unit battery cells 2000. The manufacturing method for reducing variations in the degree of compression and battery capacity will be described later.

[0081] In the stacked battery 1100, the multiple unit battery cells 2000 electrically connected in parallel have the same voltage, so if there is variation in the battery capacity of each of the multiple unit battery cells 2000, there will be large variation in the current flowing through the negative electrode current collector lead 340 and the positive electrode current collector lead 350. In contrast, in the stacked battery 1100 of this modified example, there is little variation in the battery capacity of each of the multiple unit battery cells 2000. This makes it possible to reduce variation in the current flowing through the negative electrode current collector lead 340 and the positive electrode current collector lead 350 in the stacked battery 1100. As a result, excessive temperature rise and the like can be suppressed, and localized heat generation in the unit battery cells 2000 can be suppressed, thereby improving the reliability of the stacked battery 1100.

[0082] The stacked battery according to this modification may further include a sealing member. Fig. 4 is a cross-sectional view showing a schematic configuration of a stacked battery 1100A according to this modification including a sealing member 700. As shown in Fig. 4, the stacked battery 1100A includes a sealing member 700 in addition to the configuration of the stacked battery 1100 described above.

[0083] The sealing member 700 is disposed so as to cover all of the stacked unit battery cells 2000. Parts of the negative electrode current collector lead 340 and the positive electrode current collector lead 350 are not covered by the sealing member 700 and are exposed.

[0084] By disposing the sealing member 700, the same effects as those of the above-mentioned stacked battery 1000A can be obtained.

[0085] [Laminated battery manufacturing method] Next, a method for manufacturing the laminated battery according to this embodiment will be described. Although a method for manufacturing the laminated battery 1000 will be mainly described below, the laminated battery 1100 can also be manufactured by a similar method.

[0086] The manufacturing method of the stacked battery according to the present embodiment includes a stack forming step, an individual compression step, a measurement step, a stacking step, and a batch compression step. Each step will be described in detail below. FIG. 5 is a flow chart for explaining the manufacturing method of the stacked battery according to the present embodiment. Note that the manufacturing method in the following explanation of each step is an example, and is not limited to the following method.

[0087] (1) Laminate formation process First, the laminate formation step will be described. In the manufacturing method of a stacked battery according to this embodiment, the laminate formation step is performed first. In the laminate formation step, materials for each layer that constitutes the unit battery cell 2000 are laminated to form a laminate (step S11 in FIG. 5).

[0088] 6A to 6H are cross-sectional views showing examples of the stacking configuration of the laminate formed in the laminate formation step. In the laminate formation step, for example, as shown in Fig. 6A and Fig. 6B, a laminate in which a negative electrode active material layer 110 is stacked on a negative electrode current collector 120, and a laminate in which a positive electrode active material layer 210 is stacked on a positive electrode current collector 220 are formed.

[0089] Furthermore, as shown in FIGS. 6C and 6D, a laminate may be formed in which a solid electrolyte layer 300 is laminated on each of the negative electrode active material layer 110 of the laminate shown in FIG. 6A and the positive electrode active material layer 210 of the laminate shown in FIG. 6B.

[0090] Furthermore, as shown in FIGS. 6E and 6F, a laminate in which negative electrode active material layers 110 are laminated on both sides of a negative electrode current collector 120, and a laminate in which positive electrode active material layers 210 are laminated on both sides of a positive electrode current collector 220 may be formed.

[0091] 6G, a stack may be formed in which a positive electrode active material layer 210 is stacked on the solid electrolyte layer 300 of the stack shown in FIG. 6C. As shown in FIG. 6H, a stack may be formed in which a negative electrode active material layer 110 is stacked on the solid electrolyte layer 300 of the stack shown in FIG. 6D. Note that the stack shown in FIG. 6A to FIG. 6H is an example, and the stack configuration of the stack is not limited to the example shown in FIG. 6A to FIG. 6H. For example, the stack may have the same stack configuration as the unit battery cell 2000.

[0092] The laminate can be formed, for example, by applying a paste-like paint in which the materials for the negative electrode active material layer 110, the positive electrode active material layer 210, and the solid electrolyte layer 300 are kneaded together with a solvent onto the surface of a current collector or each layer, and then drying the applied paint. The formed laminate may also be compressed in the stacking direction.

[0093] The method of compression is not particularly limited, and a flat press, a roll press, an air or gas pressure bag press, a hydrostatic press, or various other methods can be applied.

[0094] (2) Individual compression process Next, the individual compression process will be described. In the individual compression process, the laminates formed in the laminate formation process are combined and compressed as necessary to form a plurality of unit battery cells with different degrees of compression (step S12 in FIG. 5). The formed unit battery cells with different degrees of compression are the unit battery cells that are stacked in the stacking process described below.

[0095] In the individual compression step, for example, at least two of the laminates shown in Fig. 6A to Fig. 6H are laminated such that the negative electrode active material layer 110 and the positive electrode active material layer 210 face each other with the solid electrolyte layer 300 interposed therebetween. At this time, at least two laminates are laminated such that one of the negative electrode active material layer 110, the solid electrolyte layer 300, and the positive electrode active material layer 210 faces the other of the negative electrode active material layer 110, the solid electrolyte layer 300, and the positive electrode active material layer 210, and are compressed in the stacking direction to compress and bond the laminates together. In addition, when the laminate includes all layers of the unit battery cell, the laminates may be compressed in the stacking direction without being combined.

[0096] The stacking structure of the unit battery cell formed in the individual compression step is not limited to the stacking structure of the unit battery cell 2000. FIGS. 7A to 7C are cross-sectional views showing examples of stacking structures of unit battery cells formed in the individual compression step. As shown in FIGS. 7A and 7B, when the stacking body shown in FIGS. 6G and 6H is used, it may be compressed in the stacking direction without being combined with other stacking bodies to form a unit battery cell 2000A or 2000B composed of the negative electrode active material layer 110, the solid electrolyte layer 300, and the positive electrode active material layer 210 and the negative electrode current collector 120 or the positive electrode current collector 220. Also, as shown in FIG. 7C, a unit battery cell 2000C may be formed in which active material layers are stacked on both sides of each of the two current collectors, and a solid electrolyte layer 300 is further stacked on the side opposite to the current collector of the active material layer. Also, one of the solid electrolyte layers 300 located at both ends in the stacking direction of the unit battery cell 2000C may not be stacked. 7A to 7C are merely examples, and the stacking configuration of the unit battery cells is not limited to the examples shown in Figures 7A to 7C. For example, the unit battery cells formed in the individual compression step are not limited to unit battery cells including all of the anode layer 100, the cathode layer 200, and the solid electrolyte layer 300. The unit battery cells formed in the individual compression step may be unit battery cells including at least any of the anode layer 100, the cathode layer 200, and the solid electrolyte layer 300.

[0097] The method of compression in the individual compression step is not particularly limited, and a flat press, a roll press, an air or gas pressure bag press, a hydrostatic press, or any other method can be applied.

[0098] In the individual compression step, a plurality of unit battery cells with different degrees of compression are formed. In the individual compression step, the plurality of unit battery cells formed do not have to have different degrees of compression, and some of the unit battery cells may have the same degree of compression. The degree of compression is the degree to which the material of each layer constituting the unit battery cell is compressed, as measured in the measurement of mechanical properties described below. For example, the degree of compression increases as the gaps between the powder material of each layer constituting the unit battery cell become smaller and as the compression bonding of each layer progresses.

[0099] In the individual compression step, the degree of compression of the unit battery cells can be adjusted, for example, by adjusting the pressure with which the laminate is compressed when the unit battery cells are formed. FIG. 8 is a diagram for explaining an example of adjusting the degree of compression of the unit battery cells in the individual compression step. In the individual compression step, as shown in (a), (b), and (c) of FIG. 8, laminates formed with the same design of materials, shapes, etc. are compressed with different compression pressures. Specifically, the pressure with which the laminate is compressed increases in the order of (a), (b), and (c) of FIG. 8. By compressing the laminates shown in (a), (b), and (c) of FIG. 8, a plurality of unit battery cells 2001, 2002, and 2003 shown in (d), (e), and (f) of FIG. 8 are formed, respectively. In other words, a plurality of unit battery cells 2001, 2002, and 2003 with different compression degrees corresponding to the magnitude of the pressure with which the laminate is compressed are obtained. Specifically, the degree of compression increases in the order of unit battery cells 2001, 2002, and 2003. Also, for example, among the multiple unit battery cells 2001, 2002, and 2003, unit battery cell 2001 is the least compressed and therefore has the greatest thickness, and unit battery cell 2003 is the most compressed and therefore has the smallest thickness. The stacks shown in (a), (b), and (c) of Figure 8 and the unit battery cells 2001, 2002, and 2003 shown in (d), (e), and (f) of Figure 8 each have the same stacking configuration as the unit battery cell 2000 described above.

[0100] In the individual compression process, the method of adjusting the compression degree of the unit battery cells is not limited to adjusting the pressure at which the laminate is compressed when the unit battery cells are formed. The compression degree of the unit battery cells can be adjusted, for example, by adjusting the gap setting during compression, the compression time, and the compression temperature.

[0101] Furthermore, when the stack is compressed in the above-mentioned stack formation step, the degree of compression of the unit battery cells can also be adjusted by adjusting the compression conditions in the stack formation step as described above.

[0102] In the laminate formation step and the individual compression step, for example, a required number of unit battery cells for the laminated battery 1000 are formed.

[0103] In this embodiment, as long as unit battery cells that constitute a stacked battery are formed, there are no particular limitations on the method of forming the unit battery cells, and the unit battery cells may be formed by processes other than the above two processes.

[0104] (3) Measurement process Next, the measurement step will be described. In the measurement step, the characteristics of each of the multiple unit battery cells are measured (step S13 in FIG. 5). Specifically, in the measurement step, characteristics are measured to confirm the degree of compression of each of the multiple unit battery cells. For example, the characteristics measured in the measurement step are used to determine the stacking order of the multiple unit battery cells in the stacking step described below.

[0105] The characteristics measured in the measurement step may be used to adjust the degree of compression of the unit battery cells in the individual compression step. That is, in the individual compression step, the degree of compression of each of the multiple unit battery cells is adjusted based on the characteristics measured in the measurement step. For example, the characteristics of the unit battery cells formed in the individual compression step are measured, and if the measured characteristics are not within a predetermined value range, the unit battery cells are compressed again, and the compression of the unit battery cells and the measurement of the characteristics are repeated until the characteristics are within the predetermined value range. That is, the individual compression step (i.e., step S12) and the measurement step (i.e., step S13) are repeated. Also, for example, during compression of the unit battery cells in the individual compression step, the characteristics of the unit battery cells are repeatedly measured, and the compression is terminated when the measured characteristics are within a predetermined value range. That is, during the individual compression step (i.e., step S12), the measurement step (i.e., step S13) is repeated. The predetermined value range is set based on the degree of compression and accuracy of the target unit battery cells. This increases the precision of the degree of compression of each of the multiple unit battery cells stacked in the stacking process, thereby reducing variation in the degree of compression of the multiple unit battery cells 2000 in the manufactured stacked battery 1000.

[0106] In the measuring step, for example, the mechanical characteristics or electrical characteristics of each of the plurality of unit battery cells are measured as the characteristics.

[0107] In the measurement process, for example, mechanical deformation, density, hardness, etc. are measured as the mechanical properties. Such mechanical properties can be used as indicators of the degree of compression of the unit battery cells, and the degree of compression of the unit battery cells can be directly confirmed. Specifically, the greater the mechanical deformation, density, and hardness, the greater the degree of compression of the unit battery cells. When the mechanical deformation is measured as the mechanical property in the measurement process, for example, the deformation in the thickness direction of the unit battery cells is measured using a contact displacement meter, an optical displacement meter, a gap gauge, or the like. Measuring the mechanical deformation in this manner makes it possible to perform the measurement while compressing the unit battery cells, thereby shortening the process time.

[0108] In the measurement step, the electrical characteristics are measured, for example, as electrical characteristics for deriving the battery capacity of the unit battery cell. The battery capacity of the unit battery cell increases as the compression bonding of the unit battery cell progresses and the degree of compression increases. Therefore, in the measurement step, the degree of compression of the unit battery cell can be confirmed by estimating the degree of compression of the unit battery cell based on the measurement results of the electrical characteristics for deriving the battery capacity of the unit battery cell. As the electrical characteristics, charge / discharge characteristics at full charge may be measured, from which the battery capacity can be directly derived, or electrical characteristics correlated with the battery capacity may be measured, and the battery capacity may be derived by estimating the battery capacity. The battery capacity is the amount of electricity at full charge.

[0109] The measurement of the electrical characteristics can be, for example, an impedance measurement or a charge / discharge characteristic measurement, etc. That is, in the measurement step, the impedance or the charge / discharge characteristic of each of the multiple unit battery cells may be measured as the electrical characteristics.

[0110] In impedance measurements, the impedance tends to decrease as the battery capacity of the unit battery cell increases. Also, as the compression bonding of the unit battery cells progresses, the battery capacity of the unit battery cell increases and the impedance of the unit battery cell decreases. Taking advantage of this, the battery capacity of the unit battery cell is estimated by measuring the impedance.

[0111] For example, a plurality of test unit battery cells with different degrees of compression are prepared in advance, thereby preparing a plurality of test unit battery cells with different battery capacities. The test unit battery cells are prepared from the same material and stacking configuration as the unit battery cells constituting the laminated battery to be manufactured. Then, the battery capacity and impedance are measured for each of the prepared test unit battery cells, and a correlation between the battery capacity and the impedance is obtained. In this way, by measuring the impedance of the unit battery cell in the measurement process, the battery capacity and the degree of compression of the unit battery cell can be estimated from the measured impedance and the obtained correlation. Therefore, the degree of compression of the unit battery cell can be confirmed simply by measuring the impedance of the unit battery cell, and the laminated battery 1000 can be manufactured with high productivity.

[0112] The method for preparing the test unit battery cells having different battery capacities is not limited to the above method. For example, a plurality of test unit battery cells having different battery capacities may be prepared by using the same material but having different areas or thicknesses.

[0113] In measuring the charge / discharge characteristics, for example, the unit battery cell is fully charged, the charge / discharge characteristics are measured, and the battery capacity is derived from the amount of electricity charged and discharged.

[0114] In addition, as a measurement of the charge / discharge characteristics, the voltage rise characteristic of the unit battery cell with respect to the amount of charged electricity at the beginning of charging when charging at a constant current (i.e., a constant charge / discharge rate) may be measured. The battery capacity can also be estimated from such a measurement. FIG. 9 is a schematic diagram showing the relationship between the amount of charged electricity and the voltage at the beginning of charging of a unit battery cell. FIG. 9 shows the voltage (vertical axis) and the amount of charged electricity (horizontal axis) when the unit battery cell is charged at a constant current. In FIG. 9, the dotted line shows the case where the battery capacity of the unit battery cell is relatively small, and the solid line shows the case where the battery capacity of the unit battery cell is relatively large. As shown in FIG. 9, when the battery capacity of the unit battery cell is small, the voltage rise at the beginning of charging is large, and when the battery capacity of the unit battery cell is large, the voltage rise at the beginning of charging is small. In other words, when the material and shape of the unit battery cells are similar or the same, the larger the rise in voltage per unit time in a short period of time, such as several seconds to several minutes at the beginning of charging when charged at a constant current, the smaller the battery capacity at full charge is. Using this, the battery capacity of a unit battery cell is estimated by measuring the charge / discharge characteristics in a short period of time.

[0115] For example, similarly to the case of the impedance measurement described above, a plurality of test unit battery cells with different battery capacities are prepared. Then, for each of the prepared plurality of test unit battery cells, the battery capacity and the amount of voltage rise per unit time in a short time are measured, and a correlation between the battery capacity and the amount of voltage rise per unit time in a short time is obtained. In this way, by measuring the short-time charge / discharge characteristics of the unit battery cell, the battery capacity and the degree of compression of the unit battery cell can be estimated from the measured amount of voltage rise per unit time and the obtained correlation. Therefore, by measuring the short-time charge / discharge characteristics in the measurement process, the battery capacity and the degree of compression of the unit battery cell in the individual compression process can be confirmed. As a result, the degree of compression of the unit battery cell can be confirmed even in a short time, so that the stacked battery can be quickly moved to the next process of manufacturing the stacked battery. Therefore, the stacked battery 1000 can be manufactured with high productivity. In addition, since the amount of electricity to be charged is small, even if the negative electrode layer 100 and the positive electrode layer 200 come into contact with each other during manufacturing to cause a short circuit, the amount of current flowing is small, and heat generation, etc. is suppressed. Therefore, the safety during manufacturing of the stacked battery 1000 can be improved.

[0116] In addition, in obtaining the correlation between the battery capacity and the amount of voltage increase per unit time in a short period of time, the charge / discharge characteristics may be measured under multiple conditions of different charge / discharge rates (in other words, current amounts during charging / discharging) of multiple test unit battery cells, and the correlation at each charge / discharge rate may be obtained. From among the measured charge / discharge rates, an optimal charge / discharge rate for measuring the charge / discharge characteristics may be determined in terms of correlation, measurement time, etc. Furthermore, in order to improve the accuracy of estimating the battery capacity of the unit battery cell, the charge / discharge characteristics of the unit battery cell may be measured at multiple charge / discharge rates.

[0117] In the short-time measurement of the charge and discharge characteristics, for example, the charge and discharge characteristics are measured in a region of 10% or less of the battery capacity of the multiple unit battery cells. From the viewpoint of even shorter measurement times, the charge and discharge characteristics may be measured in a region of 5% or less of the battery capacity of the multiple unit battery cells, may be measured in a region of 2% or less, or may be measured in a region of 1% or less. From the viewpoint of manufacturing the stacked battery 1000 with high productivity, the measurement time for the charge and discharge characteristics is, for example, 1 minute or less. From the viewpoint of manufacturing the stacked battery 1000 with even higher productivity, the measurement time for the charge and discharge characteristics may be 30 seconds or less, 10 seconds or less, or 3 seconds or less.

[0118] In addition, in the measurement of the charge / discharge characteristics in a short time, the amount of voltage rise at the beginning of charging may be confirmed, and then discharge may be performed. In addition, when the charge / discharge characteristics are measured in a short time, the amount of current that can be passed after charging is small even if the battery is not discharged, so the battery may proceed to the next manufacturing step without discharging. In addition, when discharging is performed, the amount of voltage drop due to discharging may be confirmed.

[0119] (4) Lamination process and bulk compression process Next, the stacking step and the collective compression step will be described. In the stacking step, the stacking order of the unit battery cells having different degrees of compression is adjusted and stacked based on the degree of compression of each of the unit battery cells (step S14 in FIG. 5). Specifically, the unit battery cells are stacked in such an arrangement that the degree of compression of the two unit battery cells located at both ends in the stacking direction is lower than the degree of compression of the unit battery cell located between the two unit battery cells. The stacking order of the unit battery cells is determined based on, for example, the characteristics measured in the measurement step. Next, in the collective compression step, the unit battery cells stacked in the stacking step are compressed in the stacking direction (step S15 in FIG. 5).

[0120] FIG. 10 is a diagram for explaining the stacking step and the collective compression step. FIG. 10 shows a case where the stacking step and the collective compression step are performed using the plurality of unit battery cells 2001, 2002, and 2003 shown in FIG. 8 to manufacture a stacked battery 1000 in which the plurality of unit battery cells 2000 are stacked. In FIG. 10, in order to simplify the illustration, the stacking configuration of each layer is not shown, and each of the unit battery cells 2000, 2001, 2002, and 2003 is shown by a single rectangle with a dot pattern. In addition, the dot pattern of the unit battery cells 2000, 2001, 2002, and 2003 indicates that the higher the density of the number of dots, the higher the degree of compression. Therefore, the unit battery cells 2001, 2002, 2003, and 2000 are compressed in this order.

[0121] First, as shown in FIG. 10(a) in the stacking step, a plurality of unit battery cells 2001, 2002, and 2003 formed in the individual compression step with different degrees of compression are stacked. Specifically, the unit battery cells 2001 with the least degree of compression are arranged at both ends in the stacking direction, that is, at the upper end and the lower end in FIG. 10(a), and the unit battery cell 2003 with the most degree of compression is arranged between the two unit battery cells 2001, that is, at the center side in the stacking direction. In addition, the unit battery cell 2002 with a compression degree between the unit battery cells 2001 and 2003 is arranged between the unit battery cells 2001 and 2003. In the illustrated example, five unit battery cells are stacked, but the number of unit battery cells to be stacked is not particularly limited. The number of unit battery cells to be stacked may be two or more and four or less, or may be six or more.

[0122] Next, in a collective compression step, the stacked multiple unit battery cells 2001, 2002, and 2003 are compressed in the stacking direction as shown in Fig. 10(a). In the collective compression step, the pressure applied when compressing the stacked multiple unit battery cells 2001, 2002, and 2003 in the stacking direction acts strongest on the unit battery cells 2001 arranged at both ends in the stacking direction and weakest on the unit battery cell 2003 arranged in the center in the stacking direction. In addition, the pressure between the unit battery cells 2001 and 2003 acts on the unit battery cell 2002 arranged between the unit battery cells 2001 and 2003. Therefore, by stacking multiple unit battery cells 2001, 2002, and 2003 in the stacking order shown in Fig. 10(a) and then compressing them, it is possible to make the degree of compression of each unit battery cell 2000 after compression uniform, as shown in Fig. 10(b), thereby obtaining a stacked battery 1000 made up of unit battery cells 2000 with little variation in the degree of compression. In this way, by adjusting the stacking order of the multiple unit battery cells 2001, 2002, and 2003 with different degrees of compression, it is possible to make the degree of compression of the unit battery cells 2000 equal to or greater than that of the unit battery cell 2003, and to reduce variation in the degree of compression of each of the unit battery cells 2000.

[0123] 10, in the stacking step, the multiple unit battery cells are stacked in an arrangement such that, among adjacent unit battery cells 2001 and 2002, the degree of compression of unit battery cell 2001 located at the end side in the stacking direction is equal to or less than the degree of compression of unit battery cell 2002. Also, among adjacent unit battery cells 2002 and 2003, the multiple unit battery cells are stacked in an arrangement such that the degree of compression of unit battery cell 2002 located at the end side in the stacking direction is equal to or less than the degree of compression of unit battery cell 2003. In other words, the multiple unit battery cells 2001, 2002, and 2003 are stacked in an arrangement such that, among the multiple stacked unit battery cells, the degree of compression of one unit battery cell located at the end side in the stacking direction is equal to or less than the degree of compression of the other unit battery cell. Therefore, the compressive pressure in the collective compression process becomes stronger from the center to both ends in the stacking direction, but to counteract the increased degree of compression caused by this pressure, the unit battery cells 2001, 2002, and 2003 are stacked in an arrangement in which the degree of compression of the unit battery cells decreases from the center to both ends in the stacking direction. This can further reduce variation in the degree of compression of the unit battery cells 2000 after the collective compression process. For example, the degree of compression of each of the unit battery cells 2000 can be made substantially uniform.

[0124] In the stacking step, when current collectors are arranged at both ends of the unit battery cells in the stacking direction, as in the unit battery cells 2001, 2002, and 2003, the current collectors of the multiple unit battery cells are stacked so that they face each other. When manufacturing a series-connected stacked battery 1000, the multiple unit battery cells are stacked so that the negative electrode current collector 120 of one of the adjacent unit battery cells faces the positive electrode current collector 220 of the other of the adjacent unit battery cells. In other words, the multiple unit battery cells are stacked so that the negative electrode layer 100 of one unit battery cell and the positive electrode layer 200 of the other unit battery cell are adjacent to each other in the adjacent unit battery cells. When manufacturing a parallel-connected stacked battery 1100, the multiple unit battery cells are stacked so that the negative electrode current collectors 120 of the adjacent unit battery cells or the positive electrode current collectors 220 of the adjacent unit battery cells face each other. In other words, the multiple unit battery cells are stacked so that the negative electrode layers 100 of two adjacent unit battery cells or the positive electrode layers 200 of two adjacent unit battery cells face each other.

[0125] Also, for example, adjacent unit battery cells may be stacked via a conductive material so that the current collectors are electrically connected to each other. The conductive material may be, for example, a metal, a conductive resin, or a conductive adhesive. When adjacent unit battery cells are joined by a conductive material, a stronger stack structure of unit battery cells can be formed.

[0126] In addition, in the stacking process, for example, when a current collector and an active material layer are arranged at both ends in the stacking direction in a unit battery cell, such as unit battery cells 2000A and 2000B shown in FIGS. 7A and 7B, adjacent unit battery cells may be stacked with one active material layer facing the other current collector.

[0127] Furthermore, in the stacking step, for example, in the case where solid electrolyte layers 300 are arranged on both ends of the unit battery cells in the stacking direction as in unit battery cell 2000C shown in FIG. 7C , or in the case where solid electrolyte layers 300 and active material layers are arranged on both ends, adjacent unit battery cells may be stacked such that the solid electrolyte layer 300 of one faces the active material layer or solid electrolyte layer 300 of the other.

[0128] A stacked battery can also be produced by stacking unit battery cells 2000A, 2000B, or 2000C in this manner, and, if necessary, stacking additional current collectors or active material layers that are lacking.

[0129] Finally, as necessary, as a step of finishing the stacked battery, leads, a sealing member, an exterior body, etc. are arranged on the obtained stacked battery (step S16 in FIG. 5). Note that the stacked battery may be further compressed after step S16.

[0130] As described above, the method for manufacturing a stacked battery according to this embodiment is a method for manufacturing a stacked battery 1000 in which a plurality of unit battery cells 2000 are stacked, each of which has an anode layer 100, a cathode layer 200, and a solid electrolyte layer 300 located between the anode layer 100 and the cathode layer 200. The method for manufacturing a stacked battery includes a stacking step and a collective compression step. In the stacking step, a plurality of unit battery cells 2001, 2002, and 2003 are stacked. In the collective compression step, the plurality of unit battery cells 2001, 2002, and 2003 stacked in the stacking step are compressed in the stacking direction. In the stacking process, the multiple unit battery cells 2001, 2002, and 2003 are stacked in an arrangement such that the degree of compression of the two unit battery cells 2001 located at both ends in the stacking direction is lower than the degree of compression of the unit battery cell 2003 located between the two unit battery cells 2001.

[0131] In the batch compression process, the compression pressure is stronger on the unit battery cells located at both ends in the stacking direction, so if unit battery cells with the same degree of compression are used for compression, the degree of compression of the unit battery cells will vary, resulting in greater variation in the battery capacity of each unit battery cell. In the stacked battery 1000, the same amount of current flows through each of the multiple unit battery cells 2000 electrically connected in series, so if the battery capacities of the multiple unit battery cells 2000 vary, the unit battery cells 2000 will be overcharged and overdischarged. In the stacked battery 1100, the multiple unit battery cells 2000 electrically connected in parallel have the same voltage, so if the battery capacities of the multiple unit battery cells 2000 vary, greater variation in the current flowing through the negative electrode current collector lead 340 and the positive electrode current collector lead 350 will occur.

[0132] In contrast, in the manufacturing method of the stacked battery according to the present embodiment, the multiple unit battery cells 2001, 2002, and 2003 are stacked so that the unit battery cells 2001 that are less compressed than the unit battery cell 2003 that is located at the center of the stacking direction are located at both ends in the stacking direction. As a result, in the batch compression step, the pressure that compresses the unit battery cell 2001 that is relatively less compressed acts relatively strongly, and the pressure that compresses the unit battery cell 2003 that is relatively more compressed acts relatively weakly. By stacking the multiple unit battery cells 2001, 2002, and 2003 with different degrees of compression in the above arrangement, it is possible to cancel out the variation in the degree of compression of the unit battery cells that occurs due to the strength of the compressive pressure in the batch compression step. Therefore, it is possible to reduce the variation in the degree of compression of the multiple unit battery cells 2000 formed after the batch compression step. In addition, as the compression bonding of the unit battery cells progresses and the degree of compression increases, the battery capacity also increases. Therefore, by reducing the variation in the degree of compression among a plurality of unit battery cells, the variation in the battery capacity among the unit battery cells can also be reduced.

[0133] As a result, when a series-connected stacked battery 1000 is manufactured, it is possible to prevent overcharging and overdischarging of each of the multiple unit battery cells 2000. Furthermore, when a parallel-connected stacked battery 1100 is manufactured, it is possible to reduce the variation in current flowing through the current collecting leads that draw current from the electrodes, thereby preventing localized heat generation in the unit battery cells 2000 due to overheating caused by the flow of excessive current. Thus, the manufacturing method for a stacked battery according to this embodiment can prevent unsafe events such as deterioration and heat generation of the unit battery cells 2000, and can manufacture a stacked battery with improved reliability.

[0134] (Other embodiments) Although the stacked battery according to the present disclosure has been described above based on the embodiments, the present disclosure is not limited to these embodiments. As long as the present disclosure does not deviate from the gist of the present disclosure, various modifications conceivable by a person skilled in the art to the embodiments and other forms constructed by combining some of the components in the embodiments are also included in the scope of the present disclosure.

[0135] For example, in the above embodiment, the stacked battery is a series-connected or parallel-connected stacked battery, but is not limited thereto. The stacked battery may be a stacked battery in which series and parallel connections are combined, in which the positive electrode layers or the negative electrode layers of the series-connected stacked batteries are stacked so as to be electrically connected to each other.

[0136] In the above embodiment, the plurality of unit battery cells are formed by stacking and compressing the layers that individually constitute the unit battery cells, but this is not limited to the above. For example, the plurality of unit battery cells may be formed by forming a unit battery cell of a size that can be divided into two or more units, and then dividing the unit battery cell.

[0137] Furthermore, the above-described embodiment can be modified, replaced, added, omitted, and the like in various ways within the scope of the claims or their equivalents. [Industrial Applicability]

[0138] The laminated battery according to the present disclosure can be used as a battery in electronic devices, electric appliances, electric vehicles, and the like. [Explanation of symbols]

[0139] 100 Negative electrode layer 110 Negative electrode active material layer 120 Negative electrode current collector 200 Positive electrode layer 210 Cathode active material layer 220 Positive electrode current collector 300 solid electrolyte layer 320, 340 Negative current collector lead 330, 350 Positive current collector lead 700 Sealing member 1000, 1000A, 1100, 1100A stacked battery 2000, 2000A, 2000B, 2000C, 2001, 2002, 2003 Unit Battery Cell

Claims

1. A method for manufacturing a stacked battery in which a plurality of unit battery cells are stacked, each unit battery cell having an anode layer, a cathode layer, and a solid electrolyte layer located between the anode layer and the cathode layer, comprising: a stacking step of stacking the plurality of unit battery cells; a batch compression step of compressing the plurality of unit battery cells stacked in the stacking step in a stacking direction, In the stacking step, the plurality of unit battery cells are stacked in such an arrangement that the degree of compression of two unit battery cells located at both ends in a stacking direction is lower than the degree of compression of a unit battery cell located between the two unit battery cells. A method for manufacturing a stacked battery.

2. The method further includes, before the stacking step, an individual compression step of compressing the stack in which the positive electrode layer, the negative electrode layer, and the solid electrolyte layer are stacked in a stacking direction to form each of the plurality of unit battery cells to be stacked in the stacking step. A method for producing the laminated battery according to claim 1 .

3. The method further includes a measuring step of measuring characteristics of each of the plurality of unit battery cells, In the individual compression step, a compression degree of each of the plurality of unit battery cells to be stacked in the stacking step is adjusted based on the characteristics measured in the measuring step. The method for producing the laminated battery according to claim 2 .

4. In the measuring step, the electrical characteristics of each of the plurality of unit battery cells are measured as the characteristics. The method for producing the laminated battery according to claim 3 .

5. In the measuring step, the charge / discharge characteristics of each of the plurality of unit battery cells are measured as the electrical characteristics. The method for producing the laminated battery according to claim 4 .

6. In the measuring step, the charge / discharge characteristics are measured in a range of 10% or less of the battery capacity of the plurality of unit battery cells. The method for producing the laminated battery according to claim 5 .

7. The measurement time for the charge / discharge characteristics is 1 minute or less. The method for producing the laminated battery according to claim 5 or 6.

8. In the measuring step, the impedance of each of the plurality of unit battery cells is measured as the electrical characteristic. The method for producing the laminated battery according to claim 4 .

9. In the measuring step, mechanical characteristics of each of the plurality of unit battery cells are measured as the characteristics. The method for producing the laminated battery according to claim 5 .

10. In the measuring step, the amount of mechanical deformation of each of the plurality of unit battery cells is measured as a mechanical characteristic using a contact displacement gauge, an optical displacement gauge, or a gap gauge. The method for producing the laminated battery according to claim 9 .

11. In the stacking step, the plurality of unit battery cells are stacked in such an arrangement that the degree of compression of one unit battery cell located at an end side in the stacking direction among the plurality of unit battery cells to be stacked is equal to or less than the degree of compression of the other unit battery cell. The method for manufacturing the laminated battery according to any one of claims 1 to 10.

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