Manufacturing method of stacked battery and 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 measurement step for measuring characteristics of each of the plurality of unit battery cells; an area adjustment step for adjusting, on the basis of the characteristics of each of the plurality of unit battery cells measured in the measurement step, an effective area of each of the plurality of unit battery cells such that the battery capacity of each of the plurality of unit battery cells falls within a predetermined value range; and a lamination step for laminating the plurality of unit battery cells the effective areas of which have been adjusted in the area adjustment step.

Description

[Technical field]

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

[0002] Patent Document 1 discloses an electricity storage device in which battery cells using graphene as a conductive additive are connected in series.

[0003] Patent Document 2 discloses that unit batteries having different battery capacities are combined and stacked based on the results of measuring the battery capacity, and a cell sheet is produced in which the stacked unit batteries are connected in parallel.

[0004] Patent Document 3 discloses distributing pressure so that the peripheral portions of a stacked battery are stronger. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2016-85965 A [Patent Document 2] JP 2017-054871 A [Patent Document 3] JP 2013-200940 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 laminated 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, and includes a measuring step of measuring characteristics of each of the plurality of unit battery cells, an area adjusting step of adjusting an effective area of ​​each of the plurality of unit battery cells based on the characteristics of each of the plurality of unit battery cells measured in the measuring step so that the battery capacity of each of the plurality of unit battery cells is within a predetermined value range, and a stacking step of stacking the plurality of unit battery cells whose effective areas have been adjusted in the area adjusting step.

[0009] Furthermore, a stacked battery in one embodiment of the present disclosure is a stacked battery in which a plurality of unit battery cell batteries, each having a negative electrode layer, a positive electrode layer, and a solid electrolyte layer located between the positive electrode layer and the negative electrode layer, are stacked, and the area of ​​each of the plurality of unit battery cells is not uniform, and the area of ​​each of the two unit battery cells located at both ends in the stacking direction is smaller than the area of ​​the unit battery cell located between the two unit battery cells. Effect of the Invention

[0010] According to the present disclosure, the reliability of a stacked battery can be improved. [Brief description of the drawings]

[0011] [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 stacked battery including an intermediate electrode lead in the embodiment. [Diagram 3] FIG. 3 is a cross-sectional view showing a schematic configuration of a laminated battery including a sealing member according to an embodiment. [Figure 4] FIG. 4 is a cross-sectional view showing a schematic configuration of a stacked battery according to a modified example of the embodiment. [Diagram 5]FIG. 5 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. [Figure 6] FIG. 6 is a flowchart illustrating a method for manufacturing a stacked battery according to an embodiment. [Figure 7A] FIG. 7A 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 7B] FIG. 7B 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 7C] FIG. 7C 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 7D] FIG. 7D 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 7E] FIG. 7E 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 7F] FIG. 7F 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 7G] FIG. 7G 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 7H] FIG. 7H 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 8A] FIG. 8A is a cross-sectional view showing an example of a stacked configuration of unit battery cells formed in a compression step according to an embodiment. [Figure 8B] FIG. 8B is a cross-sectional view showing an example of a stacked configuration of unit battery cells formed in a compression step according to the embodiment. [Figure 8C] FIG. 8C is a cross-sectional view showing an example of a stacked configuration of unit battery cells formed in a 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 10A] FIG. 10A is a plan view illustrating an example of cutting positions of unit battery cells in the embodiment. [Figure 10B] FIG. 10B is a plan view illustrating an example of a cutting position of a unit battery cell according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] (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.

[0013] Therefore, the present disclosure provides a manufacturing method for a stacked battery and a stacked battery with improved reliability.

[0014] (Summary of the Disclosure) 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 of which has a negative electrode layer, a positive electrode layer, and a solid electrolyte layer located between the negative electrode layer and the positive electrode layer, and includes a measurement step of measuring characteristics of each of the plurality of unit battery cells, an area adjustment step of adjusting an effective area of ​​each of the plurality of unit battery cells based on the characteristics of each of the plurality of unit battery cells measured in the measurement step so that the battery capacity of each of the plurality of unit battery cells is within a predetermined value range, and a stacking step of stacking the plurality of unit battery cells whose effective areas have been adjusted in the area adjustment step.

[0015] As a result, the effective area of ​​each of the multiple unit battery cells, which is proportional to the battery capacity, is adjusted based on the characteristics measured in the measurement process, so that the battery capacity of the unit battery cells constituting the stacked battery can be made uniform within a predetermined range of values, such as a substantially uniform range. As a result, if the stacked battery manufactured is of a series connection type, overcharging and overdischarging of the unit battery cells can be suppressed. Furthermore, if the stacked battery is of a parallel connection type, the variation in the current flowing through the current collecting leads that draw current from the electrodes can be reduced, so that localized heat generation of the unit battery cells due to overheating or the like can be suppressed. Thus, 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, since the battery capacity can be adjusted by adjusting the effective area, the battery capacity of the entire battery stack can be adjusted with high precision without changing the thickness of the battery stack.

[0017] Also, for example, in the area adjusting step, the effective area may be adjusted by cutting each of the plurality of unit battery cells.

[0018] This makes it possible to adjust the effective area simply by adjusting the actual area by cutting, and therefore makes it possible to easily manufacture a stacked battery with improved reliability.

[0019] Furthermore, for example, in the measuring step, charge / discharge characteristics of each of the plurality of unit battery cells may be measured as the characteristics.

[0020] In this way, since the electrical quantity and voltage related to the battery capacity are measured by measuring the charge / discharge characteristics, the battery capacity of each of the unit battery cells can be adjusted with high accuracy.

[0021] 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.

[0022] 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 of the unit battery cell can be derived 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 flow is small and heat generation, etc. is suppressed. This allows the safety of the stacked battery to be improved during manufacturing.

[0023] For example, the measurement time for the charge / discharge characteristics may be one minute or less.

[0024] 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 of the unit battery cell can be derived, thereby enabling stacked batteries to be manufactured with high productivity.

[0025] Furthermore, for example, in the measuring step, impedance of each of the plurality of unit battery cells may be measured as the characteristic.

[0026] As a result, since the impedance and battery capacity of a unit battery cell are correlated, the battery capacity of the unit battery cell can be derived simply by measuring the impedance of the unit battery cell, thereby enabling stacked batteries to be manufactured with high productivity.

[0027] Furthermore, for example, in the stacking process, the plurality of unit battery cells may be stacked in an arrangement such that the area of ​​each of the two unit battery cells stacked at both ends in the stacking direction is smaller than the area of ​​the unit battery cell stacked between the two unit battery cells.

[0028] In a stacked battery manufactured by this manufacturing method, the outer peripheries of the unit battery cells located at both ends in the stacking direction do not protrude in a plan view. This prevents external impacts from concentrating on the outer peripheries of the unit battery cells in a plan view. This makes it possible to manufacture a stacked battery that reduces the risk of damage to the outer peripheries of the unit battery cells located at both ends in the stacking direction, which are susceptible to external impacts.

[0029] Also, for example, in the stacking step, after stacking the plurality of unit battery cells, only a region where all of the plurality of unit battery cells overlap when viewed from the stacking direction may be compressed.

[0030] As a result, even when the battery capacity and volumetric energy density of the stacked battery are increased by compressing the stacked battery, the regions with low mechanical strength can be prevented from being compressed because the unit battery cells are not overlapped, thereby reducing the risk of damaging the unit battery cells during the manufacture of the stacked battery.

[0031] Furthermore, a stacked battery in one embodiment of the present disclosure is a stacked battery in which a plurality of unit battery cell batteries, each having a negative electrode layer, a positive electrode layer, and a solid electrolyte layer located between the positive electrode layer and the negative electrode layer, are stacked, and the area of ​​each of the plurality of unit battery cells is not uniform, and the area of ​​each of the two unit battery cells located at both ends in the stacking direction is smaller than the area of ​​the unit battery cell located between the two unit battery cells.

[0032] This results in a structure in which the outer peripheries in plan view of the unit battery cells located at both ends in the stacking direction do not protrude, which prevents external impacts from concentrating on the outer peripheries in plan view of the unit battery cells. This reduces the risk of damage to the outer peripheries in plan view of the unit battery cells located at both ends in the stacking direction, which are susceptible to external impacts. This makes it possible to realize a stacked battery with improved reliability.

[0033] Also, for example, the battery capacities of the plurality of unit battery cells may be uniform.

[0034] This makes it possible to prevent overcharging and overdischarging of the unit battery cells when the stacked battery is of a series connection type. Also, when the stacked battery is of a parallel connection type, it is possible to reduce the variation in the current flowing through the current collecting leads that draw current from the electrodes, thereby making it possible to prevent localized heat generation in the stacked battery due to excessive temperature rise, etc. This makes it possible to prevent unsafe events such as deterioration and heat generation of the unit battery cells, thereby realizing a stacked battery with even higher reliability.

[0035] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] In addition, in this specification, the "area" and "effective area" of a stacked battery and a unit battery cell refer to the area and effective area of ​​the stacked battery and unit battery cell, respectively, when viewed in plan.

[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) 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. In the illustrated example, five unit battery cells 2000 are stacked, but the number of stacked unit battery cells 2000 is not particularly limited. The number of stacked unit battery cells 2000 may be two or more and four or less, or may be six or more.

[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 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] As shown in Fig. 1, the areas of the multiple unit battery cells 2000 constituting the stacked battery 1000 are not uniform. The areas of the multiple unit battery cells 2000 constituting the stacked battery 1000 are adjusted so that the battery capacities of the multiple unit battery cells 2000 are uniform. A method of adjusting the areas to make the battery capacities uniform will be described later. Note that uniform battery capacities mean that the battery capacities are substantially uniform. For example, the difference in battery capacity between the multiple unit battery cells 2000 may be 5% or less, 3% or less, or 1% or less.

[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 the battery capacities of the multiple unit battery cells 2000 vary, the unit battery cells 2000 will be overcharged and overdischarged. In contrast, in the stacked battery 1000 of the present embodiment, the battery capacities of the multiple unit battery cells 2000 are uniform. 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] Also, as shown in FIG. 1, the stacked battery 1000 may have a unit battery cell 2000 with a larger area arranged at the center of the stacking direction, and a unit battery cell 2000 with a smaller area arranged at both ends of the stacking direction. For example, the areas of the unit battery cells 2000 are not uniform, and the areas of the two unit battery cells 2000 located at both ends of the stacking direction among the unit battery cells 2000 are smaller than the area of ​​the unit battery cell 2000 located between the two unit battery cells 2000. This results in a structure in which the outer peripheries of the unit battery cells 2000 located at both ends of the stacking direction do not protrude in a plan view. Therefore, it is possible to suppress concentration of external impacts on the outer peripheries of the unit battery cells 2000 in a plan view. This reduces the risk of damage to the outer peripheries of the unit battery cells 2000 located at both ends of the stacking direction, which are susceptible to external impacts, in a plan view.

[0068] 1, among the multiple unit battery cells 2000 adjacent to each other, the area of ​​one unit battery cell 2000 located at an end side in the stacking direction is equal to or smaller than the area of ​​the other unit battery cell 2000. As a result, the area of ​​the unit battery cells 2000 decreases from the center toward the end in the stacking direction, so that the outer periphery of each unit battery cell 2000 is less likely to protrude in a planar view. Therefore, external impacts are less likely to concentrate on the outer periphery of the unit battery cells 2000 in a planar view, and the risk of damage to the outer periphery of each of the multiple unit battery cells 2000 in a planar view can be reduced.

[0069] The stacked battery 1000 may also include an intermediate electrode lead by utilizing the area difference between the unit battery cells 2000. FIG. 2 is a cross-sectional view showing a schematic configuration of a stacked battery 1000A including an intermediate electrode lead 310 according to the present embodiment. As shown in FIG. 2, the stacked battery 1000A includes an intermediate electrode lead 310 in addition to the configuration of the stacked battery 1000 described above. The intermediate electrode lead 310 is joined to an end of the unit battery cells 2000 in a direction perpendicular to the stacking direction, specifically, to a side surface of a current collector of the unit battery cell 2000. The intermediate electrode lead 310 is also joined to a current collector in an area where adjacent unit battery cells 2000 do not overlap in a planar view. This can increase the joining strength of the intermediate electrode lead 310. In addition, the space above or below the area where adjacent unit battery cells 2000 do not overlap in a planar view in the stacked battery 1000A can be efficiently used, so that the volumetric energy density of the stacked battery 1000A can be increased. The intermediate electrode lead 310 may be made of a metal such as nickel, stainless steel, aluminum, or copper.

[0070] The intermediate electrode lead 310 can be used, for example, to monitor the voltage of each of the unit battery cells 2000 that make up the stacked battery 1000A. This makes it possible to grasp the operating status of the unit battery cells 2000 and improve safety by controlling the stacked battery 1000 using the intermediate electrode lead 310.

[0071] The stacked battery according to this embodiment may further include a sealing member. Fig. 3 is a cross-sectional view showing a schematic configuration of a stacked battery 1000B including a sealing member 700 according to this embodiment. As shown in Fig. 3, the stacked battery 1000B 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 stacked battery 1000A described above. It is to be noted that the stacked battery 1000B does not necessarily include the intermediate electrode lead 310.

[0072] 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 1000B. 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.

[0073] The sealing member 700 is disposed so as to cover all of the stacked unit battery cells 2000. Parts of the intermediate electrode lead 310, the negative electrode current collector lead 320, and the positive electrode current collector lead 330 are exposed and not covered by the sealing member 700. The sealing member 700 is formed, for example, using an electrically insulating material.

[0074] By disposing the sealing member 700, the unit battery cell 2000 in the center that protrudes isolatedly from the end of the stacked battery 1000B can be firmly protected, improving the reliability of the stacked battery 1000B against mechanical shocks, etc. Furthermore, because the areas of the unit battery cells 2000 that make up the stacked battery 1000B are not uniform, the bonding strength between the sealing member 700 and each of the unit battery cells 2000 is improved, further improving the reliability of the stacked battery 1000B.

[0075] 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.

[0076] 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.

[0077] 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.

[0078] By providing the sealing member 700, the reliability of the stacked battery 1000B can be improved in various respects, such as mechanical strength, short-circuit prevention, and moisture resistance.

[0079] [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.

[0080] 4 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.

[0081] 4, 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.

[0082] 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.

[0083] 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.

[0084] 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.

[0085] In addition, by utilizing the area difference of the unit battery cells 2000, a negative electrode current collector lead 340 and a positive electrode current collector lead 350 are formed by bonding or the like at the end portions in the direction perpendicular to the stacking direction of the unit battery cells 2000. The negative electrode current collector lead 340 and the positive electrode current collector lead 350 are respectively bonded to the end portions in the direction perpendicular to the stacking direction of the unit battery cells 2000, specifically, to the side surfaces of the negative electrode current collector 120 and the positive electrode current collector 220 of the unit battery cells 2000. The negative electrode current collector lead 340 and the positive electrode current collector lead 350 are also respectively bonded to the negative electrode current collector 120 and the positive electrode current collector 220 in the regions where the adjacent unit battery cells 2000 do not overlap in a plan view. This can increase the bonding strength of the negative electrode current collector lead 340 and the positive electrode current collector lead 350. Furthermore, the space above or below the region in the stacked battery 1100 where adjacent unit battery cells 2000 do not overlap in a plan view can be efficiently utilized, so that the volumetric energy density of the stacked battery 1100 can be increased.

[0086] 4, similarly to the laminated battery 1000, the areas of the multiple unit battery cells 2000 constituting the laminated battery 1100 are not uniform. Furthermore, the areas of the multiple unit battery cells 2000 constituting the laminated battery 1100 are adjusted so that the battery capacities of the multiple unit battery cells 2000 are uniform. A method of adjusting the areas to make the battery capacities uniform will be described later.

[0087] In the stacked battery 1100, the multiple unit battery cells 2000 electrically connected in parallel have the same voltage, so if the multiple unit battery cells 2000 vary in battery capacity, the current flowing through the negative electrode current collector lead 340 and the positive electrode current collector lead 350 will vary greatly. In contrast, in the stacked battery 1100 of this modified example, the multiple unit battery cells 2000 have a uniform battery capacity. This makes it possible to reduce the 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.

[0088] 4, in the stacked battery 1100, similarly to the stacked battery 1000, the unit battery cells 2000 with larger areas may be arranged toward the center in the stacking direction, and the unit battery cells 2000 with smaller areas may be arranged on both ends in the stacking direction. This reduces the risk of damage to the outer peripheries, as viewed in plan, of the unit battery cells 2000 on both ends in the stacking direction.

[0089] The laminated battery according to this modification may further include a sealing member. Fig. 5 is a cross-sectional view showing a schematic configuration of a laminated battery 1100A according to this modification including a sealing member 700. As shown in Fig. 5, the laminated battery 1100A includes a sealing member 700 in addition to the configuration of the laminated battery 1100 described above.

[0090] 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.

[0091] As with the above-described stacked battery 1000B, the placement of the sealing member 700 firmly protects the central unit battery cell 2000 that protrudes isolatedly from the end of the stacked battery 1100A, improving the reliability of the stacked battery 1100A against mechanical shocks, etc. Also, because the areas of the unit battery cells 2000 that make up the stacked battery 1100A are not uniform, the bonding strength between the sealing member 700 and each of the unit battery cells 2000 is improved, further improving the reliability of the stacked battery 1100A.

[0092] [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.

[0093] The manufacturing method of the stacked battery according to the present embodiment includes a stack forming step, a compression step, a measurement step, an area adjusting step, and a stacking step. Each step will be described in detail below. FIG. 6 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 description of each step is an example, and is not limited to the following method.

[0094] (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 carried out first. In the laminate formation step, materials for each layer constituting the unit battery cell 2000 are laminated to form a laminate (step S11 in FIG. 6).

[0095] 7A to 7H are cross-sectional views showing examples of the stacking configuration of the laminate formed in the laminate forming step. In the laminate forming step, for example, as shown in Fig. 7A and Fig. 7B, 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.

[0096] Alternatively, as shown in FIGS. 7C and 7D, 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. 7A and the positive electrode active material layer 210 of the laminate shown in FIG. 7B.

[0097] Furthermore, as shown in FIGS. 7E and 7F, 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.

[0098] 7G, 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. 7C. As shown in FIG. 7H, 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. 7D. Note that the stack shown in FIG. 7A to FIG. 7H is an example, and the stack structure of the stack is not limited to the example shown in FIG. 7A to FIG. 7H. For example, the stack may have the same stack structure as the unit battery cell 2000.

[0099] 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.

[0100] 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.

[0101] (2) Compression process Next, the compression step will be described. In the compression step, the stacks formed in the stack formation step are combined and compressed as necessary to form a unit battery cell 2000 (step S12 in FIG. 6).

[0102] In the compression step, for example, at least two of the laminates shown in Fig. 7A to Fig. 7H 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 lamination direction to bond the laminates together. In addition, when the laminate includes all layers of the unit battery cell 2000, the laminates may be compressed in the lamination direction without being combined. In this way, for example, the unit battery cell 2000 is formed.

[0103] The stacking structure of the unit battery cell formed in the compression step is not limited to the stacking structure of the unit battery cell 2000. FIGS. 8A to 8C are cross-sectional views showing examples of stacking structures of unit battery cells formed in the compression step. As shown in FIGS. 8A and 8B, when the stacking body shown in FIGS. 7G and 7H 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. 8C, 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. Furthermore, the unit battery cells shown in FIGS. 8A to 8C are just examples, and the stacking configuration of the unit battery cells is not limited to the examples shown in FIGS. 8A to 8C.

[0104] The compression method in the 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.

[0105] In the laminate formation step and compression step, for example, a plurality of unit battery cells 2000 are formed in the number required for the laminated battery 1000. In addition, for example, a plurality of unit battery cells 2000 designed with the same material and shape are formed.

[0106] In this embodiment, as long as the unit battery cells 2000 that constitute the stacked battery are formed, there are no particular limitations on the method of forming the unit battery cells 2000, and the unit battery cells 2000 may be formed by processes other than the above two processes.

[0107] (3) Measurement process Next, the measurement step will be described. In the measurement step, the characteristics of each of the plurality of unit battery cells 2000 formed in the compression step are measured (step S13 in FIG. 6). Specifically, in the measurement step, characteristics for deriving the battery capacity of each of the plurality of unit battery cells 2000 are measured. That is, the battery capacity of each of the plurality of unit battery cells 2000 is derived based on the measured characteristics of each of the plurality of unit battery cells 2000. The battery capacity is the amount of electricity when fully charged.

[0108] In the measurement process, for example, electrical characteristics of electrical behavior such as charge and discharge characteristics are measured as the characteristics. In addition, in the measurement process, mechanical characteristics such as mechanical behavior during compression may be measured as the characteristics. For example, the battery capacity of the unit battery cell 2000 may be derived directly by measuring the charge and discharge characteristics at full charge as the electrical characteristics, or the battery capacity of the unit battery cell 2000 may be derived by measuring electrical characteristics or mechanical characteristics correlated with the battery capacity and estimating the battery capacity.

[0109] The measurement of the electrical characteristics of the electrical behavior can be, for example, impedance measurement or charge / discharge characteristic measurement, etc. In other words, in the measurement step, the impedance or charge / discharge characteristic of each of the multiple unit battery cells 2000 may be measured as the characteristics.

[0110] In impedance measurement, there is a tendency for the impedance to decrease as the battery capacity of the unit battery cell 2000 increases. Furthermore, as the compression bonding of the unit battery cell 2000 progresses, the battery capacity of the unit battery cell 2000 increases and the impedance of the unit battery cell 2000 decreases. Using this, the battery capacity of the unit battery cell 2000 is estimated by measuring the impedance.

[0111] For example, a plurality of test unit battery cells with different battery capacities are prepared in advance by preparing a plurality of test unit battery cells with different degrees of progress of compression bonding. 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 to obtain a correlation between the battery capacity and the impedance. In this way, by measuring the impedance of the unit battery cell 2000 in the measurement process, the degree of progress of compression bonding of the unit battery cell 2000 and the battery capacity can be estimated from the measured impedance and the obtained correlation, and the battery capacity of the unit battery cell 2000 can be derived. Therefore, the battery capacity of the unit battery cell 2000 can be derived simply by measuring the impedance of the unit battery cell 2000, so that 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 2000 is fully charged, the charge / discharge characteristics are measured, and the battery capacity is derived from the amount of electricity charged and discharged.

[0114] Furthermore, as a measurement of the charge / discharge characteristics, the voltage rise characteristic of the unit battery cell 2000 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 the unit battery cell 2000. FIG. 9 shows the voltage (vertical axis) and the amount of charged electricity (horizontal axis) when the unit battery cell 2000 is charged at a constant current. In FIG. 9, the dotted line shows the case where the battery capacity of the unit battery cell 2000 is relatively small, and the solid line shows the case where the battery capacity of the unit battery cell 2000 is relatively large. As shown in FIG. 9, when the battery capacity of the unit battery cell 2000 is small, the voltage rise at the beginning of charging is large, and when the battery capacity of the unit battery cell 2000 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 2000 are similar or the same, the greater the voltage rise per unit time in a short period of time, such as a few seconds to a few minutes at the beginning of charging when charged at a constant current, the smaller the battery capacity when fully charged. Using this, the battery capacity of the unit battery cell 2000 is estimated by measuring the charge and discharge characteristics for 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 voltage rise per unit time in a short time are measured, and a correlation between the battery capacity and the voltage rise per unit time in a short time is obtained. As a result, by measuring the short-time charge / discharge characteristics of the unit battery cell 2000, the progress of the compression bonding of the unit battery cell 2000 and the battery capacity can be estimated from the measured voltage rise per unit time and the obtained correlation, and the battery capacity of the unit battery cell 2000 can be derived. As a result, the battery capacity of the unit battery cell 2000 can be predicted 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. This can improve safety during manufacturing of the stacked battery 1000.

[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. In addition, in order to improve the accuracy of estimating the battery capacity of the unit battery cell 2000, the charge / discharge characteristics of the unit battery cell 2000 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 2000. 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 2000, 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] The mechanical properties are measured, for example, by measuring the amount of mechanical deformation, density, hardness, etc. As described above, as the compression bonding of the unit battery cells 2000 progresses, the battery capacity of the unit battery cells 2000 increases. Therefore, by measuring the amount of mechanical deformation, density, hardness, etc. as mechanical properties that can confirm the degree of progress of the compression bonding of the unit battery cells 2000, the battery capacity of the unit battery cells 2000 can be estimated. For example, the greater the amount of mechanical deformation, density, and hardness, the greater the battery capacity of the unit battery cell.

[0120] (4) Area adjustment process Next, the area adjustment step will be described. In the area adjustment step, first, based on the characteristics of each of the unit battery cells 2000 measured in the measurement step, the effective area of ​​each of the unit battery cells 2000 is determined so that the battery capacity of each of the unit battery cells 2000 falls within a predetermined value range (step S14 in FIG. 6). Then, the effective area of ​​each of the unit battery cells 2000 is adjusted so that the effective area becomes the effective area determined in step S14 (step S15 in FIG. 6). That is, in the area adjustment step, based on the characteristics of each of the unit battery cells 2000 measured in the measurement step, the effective area of ​​each of the unit battery cells 2000 is adjusted so that the battery capacity of each of the unit battery cells 2000 falls within a predetermined value range. The effective area is the area of ​​the unit battery cell 2000 that functions as a battery. As a result, the battery capacity of each of the unit battery cells 2000 is adjusted to fall within a predetermined value range.

[0121] Specifically, in step S14, based on the battery capacity derived from the characteristics of each of the multiple unit battery cells 2000 measured in the measurement process, the effective area of ​​each of the multiple unit battery cells 2000 is determined so that the battery capacity of each of the multiple unit battery cells 2000 is within a predetermined value range.

[0122] The predetermined value range is determined by the design of the battery capacity of the stacked battery 1000, and is, for example, a range in which the battery capacity of each of the multiple unit battery cells 2000 is substantially uniform. The predetermined value range may be, for example, within a range of ±2.5%, ±1.5%, or ±0.5% of the design value of the battery capacity of the unit battery cell 2000.

[0123] The battery capacity of the unit battery cell 2000 is proportional to the area of ​​the unit battery cell 2000, for example. Therefore, for example, as the unit battery cell 2000 to be subjected to area adjustment, a unit battery cell 2000 having an area in which the battery capacity of the unit battery cell 2000 before the area adjustment is assumed to be larger than the design value of the battery capacity of the unit battery cell 2000 is fabricated. Then, the adjustment, in other words, the effective area to be reduced is determined from the difference between the design value of the battery capacity of the unit battery cell 2000 and the battery capacity of the unit battery cell 2000 derived in the measurement process. For example, assuming that the design value of the battery capacity of the unit battery cell 2000 is Cs, the battery capacity of the unit battery cell 2000 derived in the measurement process is Cr, and the effective area of ​​the unit battery cell 2000 before the effective area adjustment is X, the effective area Y to be reduced is calculated by Y=X×(Cr−Cs) / Cr.

[0124] Furthermore, if the battery capacity of the unit battery cell 2000 derived in the measurement step is within a predetermined value range, the unit battery cell 2000 may be used in the subsequent stacking step without reducing its effective area. In this embodiment, adjustment of the effective area also includes not reducing the effective area. Furthermore, if the battery capacity of the unit battery cell 2000 derived in the measurement step is smaller than the predetermined value range, for example, the unit battery cell 2000 is discarded without being used in the subsequent stacking step.

[0125] In the area adjustment step, for example, each of the multiple unit battery cells 2000 is cut along the stacking direction to adjust the effective area, that is, the actual area. FIGS. 10A and 10B are plan views for explaining examples of cutting positions of the unit battery cells 2000. As shown in FIG. 10A, for example, the unit battery cells 2000 are cut at the position of a dashed line C1 along one side of the rectangular unit battery cell 2000 in a planar view. Also, as shown in FIG. 10B, the unit battery cells 2000 may be cut at the position of a dashed line C2 passing through two orthogonal sides of the unit battery cell 2000 in a planar view so that the cut portion includes a corner of the unit battery cell 2000. By cutting at the position of the dashed line C2, the corner of the unit battery cell 2000 that is vulnerable to external impact is removed, thereby improving the reliability of the stacked battery 1000. Furthermore, even if the area to be cut of the unit battery cell 2000 is small, it is not necessary to remove a long and narrow region as in the case of cutting along the side of the unit battery cell 2000 in a plan view, and the unit battery cell 2000 can be easily cut. Note that, although the unit battery cell 2000 is cut at only one location in the illustrated example, the unit battery cell 2000 may be cut at multiple locations.

[0126] The cutting method may be, for example, shear cutting, score cutting, razor cutting, ultrasonic cutting, laser cutting, jet cutting, or other various cutting methods. For example, in shear cutting, various cutting blades such as a Goebel slit blade, a gang slit blade, a rotary chopper blade, or a shear blade are used. In cutting, a Thomson blade may also be used.

[0127] The method for adjusting the effective area of ​​the unit battery cell 2000 is not limited to adjusting the actual area by cutting. For example, as a method for adjusting the effective area by a method other than cutting, a method for inactivating the power generating element (a portion composed of the negative electrode active material layer 110, the positive electrode active material layer 210, and the solid electrolyte layer 300) from the end face of the unit battery cell 2000, such as laser trimming, plasma treatment, heating, or humidification.

[0128] After step S15, the characteristics of each of the unit battery cells 2000 may be measured again to confirm the battery capacity after adjusting the effective area. The effective area of ​​the unit battery cells 2000 may be adjusted based on the reconfirmed battery capacity.

[0129] (5)Lamination process Next, the stacking step will be described. In the stacking step, first, a plurality of unit battery cells 2000 whose effective areas have been adjusted in the area adjusting step are stacked (step S16 in FIG. 6). In this way, a stacked battery 1000 is obtained.

[0130] In the stacking step, when current collectors are arranged at both ends of the unit battery cells 2000 in the stacking direction, as in the case of the unit battery cells 2000, the current collectors of the multiple unit battery cells 2000 are stacked so that they face each other. When manufacturing a series-connected stacked battery 1000, the multiple unit battery cells 2000 are stacked so that the negative electrode current collector 120 of one of the adjacent unit battery cells 2000 faces the positive electrode current collector 220 of the other of the adjacent unit battery cells 2000. In other words, the multiple unit battery cells 2000 are stacked so that the negative electrode layer 100 of one unit battery cell 2000 and the positive electrode layer 200 of the other unit battery cell 2000 are adjacent to each other in the adjacent unit battery cells 2000. When manufacturing a parallel-connected stacked battery 1100, the multiple unit battery cells 2000 are stacked so that the negative electrode current collectors 120 or the positive electrode current collectors 220 of the adjacent unit battery cells 2000 face each other. In other words, a plurality of unit battery cells 2000 are stacked so that the negative electrode layers 100 or the positive electrode layers 200 of two adjacent unit battery cells 2000 are adjacent to each other.

[0131] Also, for example, adjacent unit battery cells 2000 are 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 2000 are joined with a conductive material, a stronger stack structure of unit battery cells 2000 can be formed.

[0132] In addition, in the stacking step, the multiple unit battery cells 2000 may be arranged in such a manner that the area of ​​each of the two unit battery cells 2000 stacked at both ends in the stacking direction is smaller than the area of ​​the unit battery cells 2000 stacked between the two unit battery cells 2000. For example, the multiple unit battery cells 2000 are stacked in an arrangement as shown in FIG. 1. The stacked battery 1000 thus formed has a structure in which the outer periphery of the unit battery cells 2000 at both ends in the stacking direction does not protrude in a plan view. Therefore, concentration of external impact on the outer periphery of the unit battery cells 2000 in a plan view is suppressed. Therefore, it is possible to manufacture a stacked battery 1000 that can reduce the risk of damage to the outer periphery of the unit battery cells 2000 at both ends in the stacking direction that are susceptible to external impacts in a plan view.

[0133] Furthermore, in the stacking step, the multiple unit battery cells 2000 may be stacked in an arrangement in which the area of ​​one of the multiple unit battery cells 2000 stacked to be located at an end side in the stacking direction is equal to or smaller than the area of ​​the other unit battery cell 2000. In the stacked battery 1000 formed in this manner, the area of ​​the unit battery cells 2000 decreases from the center toward the end in the stacking direction, so that the outer periphery of each unit battery cell 2000 is unlikely to protrude in a planar view. Therefore, external impacts are unlikely to concentrate on the outer periphery of the unit battery cell 2000 in a planar view, and the risk of damage to the outer periphery of each of the multiple unit battery cells 2000 in a planar view can be reduced.

[0134] 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. 8A and 8C, adjacent unit battery cells may be stacked with one active material layer facing the other current collector.

[0135] 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. 8C , 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.

[0136] In this way, a stacked battery can also be produced by stacking unit battery cells 2000A, 2000B, or 2000C, and then stacking additional current collectors or active material layers as necessary to make up for any shortage.

[0137] In addition, in the stacking step, after stacking the multiple unit battery cells 2000, the stacked multiple unit battery cells 2000 may be compressed in the stacking direction. This can increase the battery capacity and volumetric energy density of the stacked battery 1000. In addition, when compressing the multiple stacked unit battery cells 2000 in the stacking direction, if the areas of the multiple unit battery cells 2000 are not uniform, only the area where all of the multiple unit battery cells 2000 overlap as viewed from the stacking direction may be compressed. This can prevent the area where the multiple unit battery cells 2000 do not overlap and therefore have low mechanical strength from being compressed. This can reduce the risk of the unit battery cells 2000 being damaged. For example, a jig or the like having a shape of the area where all of the multiple unit battery cells 2000 overlap as viewed from the stacking direction is sandwiched between the compression device and the stacked battery, and only the area is compressed.

[0138] 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 S17 in FIG. 6). Note that the stacked battery may be further compressed after step S17.

[0139] As described above, the manufacturing method of the laminated battery according to the present embodiment is a manufacturing method of the laminated battery 1000 in which a plurality of unit battery cells 2000 each having 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 are stacked. The manufacturing method of the laminated battery 1000 includes a measuring step, an area adjusting step, and a stacking step. In the measuring step, the characteristics of each of the plurality of unit battery cells 2000 are measured. In the area adjusting step, the effective area of ​​each of the plurality of unit battery cells 2000 is adjusted based on the characteristics of each of the plurality of unit battery cells 2000 measured in the measuring step so that the battery capacity of each of the plurality of unit battery cells 2000 falls within a predetermined value range. In the stacking step, the plurality of unit battery cells 2000 whose effective area has been adjusted in the area adjusting step are stacked.

[0140] As a result, the effective area of ​​each of the multiple unit battery cells 2000, which is proportional to the battery capacity, is adjusted based on the characteristics measured in the measurement process, so that the battery capacity of each of the multiple unit battery cells 2000 constituting the stacked battery can be made uniform within a predetermined range of values, such as a substantially uniform range. As a result, when a series-connected stacked battery 1000 is manufactured, overcharging and overdischarging of each of the multiple unit battery cells 2000 can be suppressed. Furthermore, when a parallel-connected stacked battery 1100 is manufactured, the variation in current flowing through the current collecting leads that draw current from the electrodes can be reduced, so that localized heat generation of the unit battery cells 2000 due to overheating caused by excessive current flow can be suppressed. Thus, 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 2000, and can manufacture a stacked battery with improved reliability.

[0141] As a result, in the battery stack according to this embodiment, the battery capacity of the entire battery stack can be adjusted with high precision without changing the thickness of the battery stack.

[0142] (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.

[0143] 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.

[0144] In the above embodiment, the area of ​​the unit battery cells in the stacked battery decreases from the center to the ends in the stacking direction, but this is not limited to the above. The area of ​​the unit battery cells does not have to decrease from the center to the ends in the stacking direction. For example, when a sealing member is disposed, a unit battery cell with a relatively small area is sandwiched between two unit battery cells with a relatively large area, so that the sealing member can fit between the two unit battery cells with a large area, and the multiple unit battery cells are firmly held by the sealing member.

[0145] 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.

[0146] In the above embodiment, the areas of the unit battery cells constituting the stacked battery are different, but this is not limited to the above. For example, if the effective area of ​​each of the unit battery cells is adjusted by a method of inactivating the power generating element by laser trimming, plasma treatment, heating, humidification, etc., the actual area of ​​each of the unit battery cells may be the same.

[0147] 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]

[0148] The stacked battery according to the present disclosure can be used as a stacked battery in electronic devices, electric appliances, electric vehicles, and the like. [Explanation of symbols]

[0149] 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 310 Intermediate electrode lead 320, 340 Negative current collector lead 330, 350 Positive current collector lead 700 Sealing member 1000, 1000A, 1000B, 1100, 1100A stacked battery 2000, 2000A, 2000B, 2000C unit battery cells

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 measuring step of measuring characteristics of each of the plurality of unit battery cells; an area adjusting step of adjusting an effective area of ​​each of the plurality of unit battery cells based on the characteristics of each of the plurality of unit battery cells measured in the measuring step so that a battery capacity of each of the plurality of unit battery cells falls within a predetermined value range; a stacking step of stacking the plurality of unit battery cells whose effective areas have been adjusted in the area adjusting step. A method for manufacturing a stacked battery.

2. In the area adjusting step, the effective area is adjusted by cutting each of the plurality of unit battery cells. A method for producing the laminated battery according to claim 1 .

3. In the measuring step, the charge / discharge 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 1 or 2.

4. 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 3 .

5. The measurement time for the charge / discharge characteristics is 1 minute or less. The method for producing the laminated battery according to claim 3 or 4.

6. In the measuring step, the impedance of each of the plurality of unit battery cells is measured as the characteristic. The method for producing the laminated battery according to claim 1 or 2.

7. In the stacking step, the plurality of unit battery cells are stacked in such an arrangement that the areas of two unit battery cells stacked at both ends in the stacking direction are both smaller than the area of ​​a unit battery cell stacked between the two unit battery cells. A method for producing the laminated battery according to any one of claims 1 to 6.

8. In the stacking step, after stacking the plurality of unit battery cells, only a region where all of the plurality of unit battery cells overlap when viewed from a stacking direction is compressed. A method for producing the laminated battery according to any one of claims 1 to 7.

9. 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 cathode layer and the anode layer, The areas of the unit battery cells are not uniform, among the plurality of unit battery cells, each of two unit battery cells located at both ends in a stacking direction has an area smaller than an area of ​​a unit battery cell located between the two unit battery cells; The battery capacity of each of the plurality of unit battery cells is uniform. Stacked battery.

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