Method of manufacturing multilayer battery, multilayer battery and battery pack

Abstract

To provide a method of manufacturing a multilayer battery in which an outermost multilayer battery unit is hard to crack, a multilayer battery which can be manufactured by such a manufacturing method, and a battery pack including such a multilayer battery.SOLUTION: A method of manufacturing a multilayer battery 10 includes the steps of: (a) providing a plurality of multilayer battery units 100 each successively including a first collector layer 110, a first electrode active material layer 120, a solid electrolyte layer 130, a second electrode active material layer 140, and a second collector layer 150; and (b) mutually laminating the plurality of multilayer battery units in such a manner that an end face of an outermost multilayer battery unit is positioned inside of an end face of the other adjacent multilayer battery unit on at least a first end face of the multilayer battery. A battery pack 1 comprises a plurality of multilayer batteries. In the battery pack, the plurality of multilayer batteries in 50% or more is the multilayer batteries of the present disclosure.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] As disclosed in Patent Document 1, a stacked battery is known in which a plurality of stacked battery units each having a first current collector layer, a first electrode active material layer, a solid electrolyte layer, a second electrode active material layer, and a second current collector layer in this order are stacked on top of each other.

[0003] Patent Document 1 discloses that when a plurality of stacked battery units are stacked on top of each other, misalignment may occur in the planar direction between the stacked battery units. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2020-161298 Summary of the Invention [Problem to be solved by the invention]

[0005] The present inventors have discovered that the above-described misalignment can cause cracks to occur in the outermost stacked battery unit among the stacked battery units.

[0006] An object of the present disclosure is to provide a method for manufacturing a stacked battery in which the outermost stacked battery unit is less likely to crack, a stacked battery in which the outermost stacked battery unit is less likely to crack, and a battery pack including such a stacked battery. [Means for solving the problem]

[0007] The present inventors have found that the above problems can be solved by the following means. <Aspect 1> A method for manufacturing a stacked battery, comprising the steps of: (a) providing a plurality of stacked battery units each having a first current collector layer, a first electrode active material layer, a solid electrolyte layer, a second electrode active material layer, and a second current collector layer in this order; (b) stacking the plurality of stacked battery units on one another such that, at least on a first end face of the stacked battery, the end face of the outermost stacked battery unit is positioned more inward than the end faces of the other adjacent stacked battery units; <Aspect 2> the end faces of the first electrode active material layer, the solid electrolyte layer, and the second electrode active material layer in the plurality of stacked battery units all have inclined surfaces that approach the first current collector layer toward their tips, and the inclined surfaces are formed on second end faces of the stacked batteries that face the first end faces. <Aspect 3> Aspect 3. The method of aspect 2, wherein the inclined surface is formed due to a length between opposing end faces of the second electrode active material layer being shorter than a length between opposing end faces of the first electrode active material layer. <Aspect 4> The method of any one of aspects 1 to 3, wherein in step (b), the plurality of stacked battery units are stacked one on top of another such that an end face of an outermost stacked battery unit on a second end face opposing the first end face of the stacked battery does not extend beyond an end face of another adjacent stacked battery unit. <Aspect 5> Aspect 2. The method of aspect 1, wherein in step (b), the position of the end face of the outermost stacked battery unit on at least the first end face of the stacked battery is determined by image processing. <Aspect 6> A stacked battery in which a plurality of stacked battery units are stacked on top of each other, each of the plurality of stacked battery units has a first current collector layer, a first electrode active material layer, a solid electrolyte layer, a second electrode active material layer, and a second current collector layer in this order; At least a first end face of the stacked battery, the end face of the outermost stacked battery unit is located more inward than the end faces of the other adjacent stacked battery units. Stacked battery. <Aspect 7> 7. The stacked battery of claim 6, wherein end faces of the first electrode active material layer, the solid electrolyte layer, and the second electrode active material layer in the stacked battery unit all have inclined surfaces that approach the first current collector layer toward their tips, and the inclined surfaces are formed on a second end face of the stacked battery that faces the first end face. <Aspect 8> Aspect 8. The stacked battery of aspect 6 or 7, wherein an outermost stacked battery unit does not extend beyond an end face of another adjacent stacked battery unit at a second end face of the stacked battery that faces the first end face. <Aspect 9> 9. The stacked battery according to any one of aspects 6 to 8, wherein, at least on the first end face of the stacked battery, when viewed in a planar direction, the distance between the end face of an outermost stacked battery unit and an end face of another adjacent stacked battery unit is 0.1 mm or more and 1.0 mm or less. <Aspect 10> A battery pack having a plurality of stacked batteries, A battery pack in which 50% or more of the plurality of stacked batteries are the stacked battery according to any one of aspects 6 to 9. [Effects of the Invention]

[0008] The manufacturing method of the present disclosure can provide a stacked battery in which the outermost stacked battery unit is less likely to crack, and the present disclosure can also provide a battery pack including such a stacked battery. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram illustrating the method of the present disclosure for manufacturing a stacked battery. [Figure 2] FIG. 2 is a schematic diagram illustrating the method of the present disclosure for manufacturing a stacked battery. [Figure 3] FIG. 3 is a schematic cross-sectional view showing an example of a stacked battery according to the present disclosure. [Figure 4] FIG. 4 is a schematic cross-sectional view showing an example of the second end surface of the stacked battery of the present disclosure. [Figure 5] FIG. 5 is a schematic cross-sectional view showing an example of a stacked battery according to the present disclosure. [Figure 6] FIG. 6 is a schematic cross-sectional view showing an example of a stacked battery according to the present disclosure. [Figure 7] FIG. 7 is a schematic diagram showing an example of a battery pack according to the present disclosure. [Figure 8] FIG. 8 is a schematic diagram illustrating a stacked battery according to the prior art. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. Note that the present disclosure is not limited to the following embodiments, and various modifications can be made within the scope of the present disclosure. Furthermore, the dimensional relationships in the drawings do not reflect the actual dimensional relationships.

[0011] <<Laminated Battery Manufacturing Method>> As illustrated in FIGS. 1 and 2 , the method of the present disclosure for manufacturing a stacked battery 10 includes the following steps: (a) providing a plurality of stacked battery units 100 each having a first current collector layer 110, a first electrode active material layer 120, a solid electrolyte layer 130, a second electrode active material layer 140, and a second current collector layer 150 in this order; and (b) stacking the plurality of stacked battery units on one another such that, at least on a first end face of the stacked battery, the end face of the outermost stacked battery unit is positioned more inward than the end faces of the adjacent stacked battery units.

[0012] The present inventors have determined that one of the causes of cracking of the outermost battery unit 100 is misalignment in the planar direction between the battery units when stacking multiple battery units. For example, during the manufacturing process of the battery 10, stress may be applied to the battery in the stacking direction of the battery units due to pressing the battery units 100 after stacking them, restraining the manufactured battery units to form a battery module, or subjecting the manufactured battery to vibrations and other shocks when the vehicle moves after the battery is mounted on a moving object such as a vehicle. In such cases, excessive stress is likely to be applied to the battery units extending from the end faces of adjacent battery units 100, as illustrated in FIG. 8 . This problem is particularly pronounced when the battery unit extending from the end face of the adjacent battery unit 100 is the outermost battery unit.

[0013] In this regard, the present inventors have discovered that by stacking a plurality of battery units on top of each other such that, at least on the first end face of the battery 10, the end face of the outermost battery unit 100 is positioned more inward than the end faces of the other adjacent battery units, as illustrated in FIGS. 1(b) and 2(b), it is possible to prevent stress from concentrating on the outermost battery unit, and therefore make the outermost battery unit less likely to crack.

[0014] In the context of this disclosure, "battery stack unit" means elements that can be stacked together to form a battery stack.

[0015] In the present disclosure, the "outermost battery unit" refers to the battery unit that is arranged outermost in the stacking direction of the battery units. That is, for example, when the battery units are stacked vertically as illustrated in Figures 1(b) and 2(b), the "outermost battery unit" refers to the battery units that are arranged on the uppermost and lowermost sides.

[0016] In the present disclosure, the term "inner side" refers to the center side of the stacked battery unit 100 in the planar direction.

[0017] The methods of the present disclosure are described in more detail below.

[0018] <Stacked battery unit provision process> As illustrated in FIGS. 1(a) and 2(a), the disclosed method for manufacturing a stacked battery 10 includes: (a) providing a plurality of stacked battery units 100 each having, in this order, a first current collector layer 110, a first electrode active material layer 120, a solid electrolyte layer 130, a second electrode active material layer 140, and a second current collector layer 150.

[0019] The method for producing the stacked battery unit 100 is not particularly limited. For example, the stacked battery unit can be produced by stacking the layers constituting the stacked battery unit in a desired order. The method for stacking the layers is not particularly limited, and examples include a method in which the first electrode active material layer 120, the solid electrolyte layer 130, and the second electrode active material layer 140 are formed by powder compaction and then stacked in a desired order. Another example includes a method in which composite slurries capable of forming the first electrode active material layer 120, the solid electrolyte layer 130, and the second electrode active material layer 140 are applied to substrates, dried, and then stacked in a desired order. The substrate of the first electrode active material layer 120 may be, for example, the first current collector layer 110. The substrate of the solid electrolyte layer 130 may be, for example, a peelable metal foil such as aluminum foil. The substrate of the second electrode active material layer 140 may be, for example, the second current collector layer 150.

[0020] In particular, when the second end face has an inclined surface 100a described below, a desired stacked battery unit can be obtained by forming a first electrode active material layer, a solid electrolyte layer, and a second electrode active material layer in this order on the first current collector layer, and then stacking a second current collector layer on the second electrode active material layer, so that the leading edge of the first electrode active material layer is located inside the leading edge of the first current collector layer, the leading edge of the solid electrolyte layer is located inside the leading edge of the first electrode active material layer, and the leading edge of the second electrode active material layer is located inside the leading edge of the solid electrolyte layer. The first electrode active material layer, the solid electrolyte layer, and the second electrode active material layer can be formed by repeatedly applying and drying composite slurries that can form each layer. By cutting the stacked body at the first end face parallel to the stacking direction before stacking the second current collector layer, the positions of the end faces of each layer can be aligned with each other in the planar direction of the stacked battery unit.

[0021] As long as the stacked battery unit 100 provided in the stacked battery unit providing step has, in at least a portion thereof, the first current collector layer 110, the first electrode active material layer 120, the solid electrolyte layer 130, the second electrode active material layer 140, and the second current collector layer 150 in this order, in the other portions thereof, the order in which the layers are stacked is not particularly limited.

[0022] For example, a first electrode active material layer 120, a solid electrolyte layer 130, a second electrode active material layer 140, and a second current collector layer 150 may be laminated in this order on both sides of a first current collector layer 110. That is, the second current collector layer 150, the second electrode active material layer 140, the solid electrolyte layer 130, the first electrode active material layer 120, the first current collector layer 110, the first electrode active material layer 120, the solid electrolyte layer 130, the second electrode active material layer 140, and the second current collector layer 150 may be laminated in this order. In this case, the "first current collector layer" and the "first electrode active material layer" may be counter electrodes to the "second current collector layer" and the "second electrode active material layer," respectively. That is, when the "first current collector layer" and the "first electrode active material layer" are respectively a "positive electrode current collector layer" and a "positive electrode active material layer," the "second current collector layer" and the "second electrode active material layer" may be respectively a "negative electrode current collector layer" and a "negative electrode active material layer." Similarly, when the "first current collector layer" and the "first electrode active material layer" are respectively a "negative electrode current collector layer" and a "negative electrode active material layer," the "second current collector layer" and the "second electrode active material layer" may be respectively a "positive electrode current collector layer" and a "positive electrode active material layer."

[0023] Alternatively, for example, the first current collector layer 110, the first electrode active material layer 120, the solid electrolyte layer 130, the second electrode active material layer 140, the second current collector layer 150, the first electrode active material layer 120, the solid electrolyte layer 130, the second electrode active material layer 140, and the first current collector layer 110 may be stacked in this order. In this case, the "first current collector layer" and the "second current collector layer" may both be current collectors that function as both a positive electrode current collector and a negative electrode current collector, and the "first electrode active material layer" and the "second electrode active material layer" may be either a "positive electrode active material layer" or a "negative electrode active material layer," respectively. That is, in this case, the stacked battery 10 manufactured by the method of the present disclosure may be a bipolar battery.

[0024] <Stacked battery unit stacking process> As illustrated in Figures 1(b) and 2(b), the method of the present disclosure for manufacturing a stacked battery 10 includes (b) stacking a plurality of stacked battery units on one another so that, at least a first end face of the stacked battery, the end face of the outermost stacked battery unit 100 is positioned more inward than the end faces of other adjacent stacked battery units. That is, the method includes stacking a plurality of stacked battery units on one another so that, at one or both of the mutually opposing end faces, the end face of the outermost stacked battery unit 100 is positioned more inward than the end faces of other adjacent stacked battery units. Note that, although Figures 1(b) and 2(b) illustrate an embodiment in which four stacked battery units are illustrated, the number of stacked battery units in a stacked battery of the present disclosure is not limited to this.

[0025] As illustrated in Figures 1(b) and 2(b), the positions of the end faces of the layers constituting the battery unit may coincide with one another in the plane direction of the battery unit at the first end face. In this case, in a conventional battery stack as illustrated in Figure 3, stress tends to concentrate on the outermost battery unit, which is thought to be prone to cracking. In contrast, in a battery stack manufactured by the method of the present disclosure, multiple battery units are stacked such that the end face of the outermost battery unit is located more inward than the end faces of the adjacent battery units at least in the first end face. This prevents stress from concentrating on the outermost battery unit, even if the positions of the end faces of the layers constituting the battery unit coincide with one another in the plane direction of the battery unit at the first end face, making the outermost battery unit less likely to crack.

[0026] FIG. 3 is a schematic cross-sectional view illustrating a stacked battery according to the present disclosure manufactured by the method shown in FIG. 1 . FIG. 4 is a schematic cross-sectional view illustrating an enlarged second end face of the stacked battery according to the present disclosure. While the end faces of the first electrode active material layer, solid electrolyte layer, and second electrode active material layer in the plurality of stacked battery units 100 are shown in a simplified form in FIG. 4 , each end face may have an inclined surface 100a that approaches the first current collector layer toward the tip. In this case, the inclined surface may be formed on the second end face facing the first end face of the stacked battery 10. When the inclined surface is formed on the second end face, stress locally applied to the outermost stacked battery unit is reduced compared to when the end faces are aligned in the planar direction of the stacked battery unit, thereby making the outermost stacked battery unit less likely to crack.

[0027] The inclined surface may be formed because the length between the opposing end faces of the second electrode active material layer 140 is shorter than the length between the opposing end faces of the first electrode active material layer 120.

[0028] For example, in lithium-ion secondary batteries, the positive electrode active material layer may be made smaller in the planar direction than the negative electrode active material layer to prevent dendrite deposition on the negative electrode active material layer. In such cases, the "first electrode active material layer" may be the negative electrode active material layer, and the "second electrode active material layer" may be the positive electrode active material layer. Furthermore, the "first current collector layer" may be the negative electrode current collector layer, and the "second current collector layer" may be the positive electrode current collector layer. In this case, the second electrode active material layer serving as the positive electrode current collector layer may extend from the first end face, and the first electrode active material layer serving as the negative electrode current collector layer may extend from the second end face.

[0029] When all the stacked battery units have the above-described inclined surface on the second end surface, the sizes of the stacked battery units may be the same or different.

[0030] 2(b), in step (b), the multiple battery units can be stacked one on top of another such that the end face of the outermost battery unit 100 at the second end face facing the first end face of the battery 10 does not extend beyond the end faces of the adjacent battery units. This configuration prevents stress from concentrating on the outermost battery unit at the second end face, making the outermost battery unit less likely to crack.

[0031] 5 and 6 are schematic cross-sectional views illustrating a stacked battery according to the present disclosure manufactured by the method shown in Fig. 2(b). As illustrated in Fig. 5 and 6, the positions of the end faces of the layers constituting the stacked battery unit at the second end face may coincide with each other in the planar direction of the stacked battery unit.

[0032] By providing a plurality of stacked battery units with different lengths between their first end faces and their second end faces and using an outermost stacked battery unit with a shorter length than the other adjacent stacked battery units, the end face of the outermost stacked battery unit at the second end face of the stacked battery does not extend beyond the end faces of the other adjacent stacked battery units, and the plurality of stacked battery units can be stacked on top of each other.

[0033] As long as the end face of the outermost stacked battery unit does not extend beyond the end face of the adjacent stacked battery unit at the second end face of the stacked battery, the positional relationship between the end face of the outermost stacked battery unit and the end face of the adjacent stacked battery unit is not particularly limited.

[0034] For example, as illustrated in FIG. 5, multiple stacked battery units may be stacked on one another such that the position of the end face of the outermost stacked battery unit at the second end face of the stacked battery coincides with the position of the end face of another adjacent stacked battery unit in the planar direction.

[0035] Furthermore, for example, as illustrated in FIG. 6, multiple stacked battery units may be stacked on one another such that the end face of the outermost stacked battery unit is positioned more inward than the end faces of the other adjacent stacked battery units at the second end face of the stacked battery.

[0036] In the context of the present disclosure, "the end face of the outermost stacked battery unit does not extend beyond the end face of the adjacent other stacked battery unit" may also encompass the case where the end face of the outermost stacked battery unit does not substantially extend beyond the end face of the adjacent other stacked battery unit. "Substantially not extending" means that the end face of the outermost stacked battery unit extends beyond the end face of the adjacent other stacked battery unit by a length of 150 μm or less, 100 μm or less, 50 μmm or less, 30 μmm or less, 10 μmm or less, 5 μm or less, or 1 μm or less.

[0037] Even in the stacked battery units having the above-described inclined surfaces, multiple stacked battery units can be stacked on top of each other so that the end face of the outermost stacked battery unit on the second end face of the stacked battery does not extend beyond the end faces of the adjacent stacked battery units.

[0038] Note that with respect to the stacked battery units other than the outermost stacked battery unit and other stacked battery units adjacent thereto, the stacked battery units can be stacked with the first end faces of the stacked battery units at any position without any particular restrictions on the end face position.

[0039] In step (b), the position of the end face of the outermost stacked battery unit 100 on at least the first end face of the stacked battery 10 can be determined by image processing. Specifically, for example, a camera included in the image processing device can be used to capture an image of the stacked battery unit from a surface direction, and the position of the outermost stacked battery unit can be determined using the position of the end face of another stacked battery adjacent to the outermost stacked battery as a reference. In this case, the position of the outermost stacked battery unit relative to the reference can be set in advance, and a computer can be caused to execute control such that the outermost stacked battery unit can be automatically positioned in a desired position using a robot arm or the like based on information about the reference based on image data acquired by the camera and information about the preset position of the outermost stacked battery unit.

[0040] <Other processes> The method of the present disclosure may further include, after step (b), a step of pressing the stacked battery units in the stacking direction. Even if the method of the present disclosure further includes such a pressing step, it is possible to prevent stress from concentrating on the outermost battery unit, thereby making the outermost battery unit less likely to crack. The pressing method is not particularly limited, and a conventional method can be used.

[0041] The pressure during pressing is not particularly limited, but may be, for example, 0.1 MPa or more and 1 MPa or less.

[0042] 《Stacked battery》 3 and 4 , in the stacked battery 10 of the present disclosure, a plurality of stacked battery units 100 are stacked on one another. Each of the plurality of stacked battery units has, in this order, a first current collector layer 110, a first electrode active material layer 120, a solid electrolyte layer 130, a second electrode active material layer 140, and a second current collector layer 150. At least on a first end face of the stacked battery, the end face of the outermost stacked battery unit is located more inward than the end faces of the adjacent stacked battery units.

[0043] This configuration prevents stress from concentrating on the outermost stacked battery unit, making the outermost stacked battery unit less likely to crack.

[0044] The laminated battery of the present disclosure may be, for example, a lithium-ion secondary battery. Examples of uses of the battery include power sources for vehicles such as hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), electric vehicles (BEVs), gasoline-powered vehicles, and diesel-powered vehicles. It is particularly preferred that the battery be used as a driving power source for hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), or electric vehicles (BEVs). The battery of the present disclosure may also be used as a power source for mobile objects other than vehicles (for example, trains, ships, and aircraft), or as a power source for electrical appliances such as information processing devices.

[0045] The elements that make up the stacked battery of the present disclosure will be described below.

[0046] <Stacked battery unit> When viewed in the planar direction, at least on the first end face of the battery stack 10, the distance between the end face of the outermost battery unit 100 and the end face of another adjacent battery unit may be 0.1 mm or more and 1.0 mm or less. This distance may be 0.1 mm or more, 0.2 mm or more, 0.3 mm or more, 0.4 mm or more, or 0.5 mm or more, and may be 1.0 mm or less, 0.9 mm or less, 0.8 mm or less, 0.7 mm or less, 0.6 mm or less, 0.5 mm or less, 0.4 mm or less, or 0.3 mm or less. This distance may be within the above range from the viewpoints of the resistance to cracking of the outermost battery stack and the structural efficiency of the battery stack in the planar direction.

[0047] In the stacked battery 10 of the present disclosure, the end faces of the first electrode active material layer, the solid electrolyte layer, and the second electrode active material layer in the stacked battery unit 100 may all have inclined surfaces that approach the first current collector layer toward the tip, and in this case, the inclined surfaces may be formed on the second end face that faces the above-mentioned first end face of the stacked battery.

[0048] In the stacked battery 10 of the present disclosure, the outermost stacked battery unit 100 does not need to extend beyond the end face of the adjacent stacked battery unit at the second end face that faces the above-mentioned first end face of the stacked battery.

[0049] The number of stacked battery units is not particularly limited and may be, for example, 3 or more, 4 or more, 5 or more, 6 or more, 7 or more, 8 or more, 9 or more, or 10 or more, and may be 50 or less, 45 or less, 40 or less, 35 or less, 30 or less, or 25 or less.

[0050] The thickness of the stacked battery unit is not particularly limited and can be set appropriately depending on the application of the stacked battery, etc. For example, the thickness of the stacked battery unit may be 50 μm or more, 100 μm or more, or 150 μm or more, and may be 500 μm or less, 400 μm or less, 300 μm or less, 250 μm or less, or 200 μm or less.

[0051] The planar shape of the stacked battery unit is not particularly limited, but may be, for example, a square.

[0052] The size of the stacked battery unit is not particularly limited, and can be designed appropriately depending on, for example, the desired battery characteristics.

[0053] The following describes each of the components that can constitute a stacked battery unit according to the present disclosure.

[0054] To facilitate understanding of the present disclosure, the components of a stacked battery unit of a lithium-ion secondary battery, which is a solid-state battery, will be described as an example, but the stacked battery of the present disclosure is not limited to this. In the present disclosure, a "solid-state battery" refers to a battery that uses at least a solid electrolyte as an electrolyte. Therefore, a solid-state battery may use a combination of a solid electrolyte and a liquid electrolyte as the electrolyte. Furthermore, the solid-state battery of the present disclosure may be an all-solid-state battery, i.e., a battery that uses only a solid electrolyte as the electrolyte.

[0055] (Positive electrode current collector layer) The conductive material used for the positive electrode current collector layer is not particularly limited, and may be, for example, SUS, aluminum, copper, nickel, iron, titanium, carbon, or the like.

[0056] The shape of the positive electrode current collector layer is not particularly limited, and examples thereof include foil, plate, mesh, etc. Among these, the foil shape is preferred.

[0057] The positive electrode current collector layer may extend from an end face of the stacked battery unit, and multiple positive electrode current collector layers may be joined at the extending portion. The positive electrode current collector layer may extend from, for example, a first end face of the stacked battery unit.

[0058] (Cathode active material layer) The positive electrode active material layer contains at least a positive electrode active material, and preferably further contains a solid electrolyte described below. In addition, depending on the intended use and purpose, it may contain additives used in positive electrode active material layers of solid-state batteries, such as a conductive additive or a binder.

[0059] The material of the positive electrode active material is not particularly limited. For example, the positive electrode active material may be lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), lithium manganese oxide (LiMn2O4), Li 1.5 Co 1 / 3 Ni 1 / 3 Mn 1 / 3 O2, LiCo 1 / 3 Ni 1 / 3 Mn 1 / 3 O2, Li 1+x Mn 2-x-y M y It may be a different element-substituted Li-Mn spinel having a composition represented by O4 (M is one or more metal elements selected from Al, Mg, Co, Fe, Ni, and Zn), or the like.

[0060] The conductive additive is not particularly limited, and may be, for example, a carbon material such as VGCF (Vapor Grown Carbon Fiber) or carbon nanofiber, or a metal material.

[0061] The binder is not particularly limited, and may be, for example, polyvinylidene fluoride (PVdF), carboxymethyl cellulose (CMC), butadiene rubber (BR), styrene butadiene rubber (SBR), or a combination thereof.

[0062] (solid electrolyte layer) The solid electrolyte layer includes at least a solid electrolyte. The solid electrolyte is not particularly limited, and any material that can be used as a solid electrolyte for a solid-state battery can be used. For example, the solid electrolyte may be a sulfide solid electrolyte, an oxide solid electrolyte, a polymer electrolyte, or the like.

[0063] Examples of sulfide solid electrolytes include, but are not limited to, sulfide-based amorphous solid electrolytes, sulfide-based crystalline solid electrolytes, and argyrodite-type solid electrolytes. Specific examples of sulfide solid electrolytes include Li2S-P2S5-based (Li7P3S 11 , Li3PS4, Li8P2S9, etc.), Li2S-SiS2, LiI-Li2S-SiS2, LiI-Li2S-P2S5, LiI-LiBr-Li2S-P2S5, Li2S-P2S5-GeS2(Li 13 GeP3S 16 , Li 10 GeP2S 12 ), LiI-Li2S-P2O5, LiI-Li3PO4-P2S5, Li 7-x PS 6-x Cl x etc.; or combinations thereof, but are not limited to these.

[0064] An example of an oxide solid electrolyte is Li7La3Zr2O 12、 Li 7-x La3Zr 1-x Nb x O 12、 Li7-3x La3Zr2Al x O 12 , Li 3x La 2 / 3-x TiO3, Li 1+x Al x Ti 2-x (PO4)3, Li 1+x Al x Ge 2-x (PO4)3, Li3PO4, Li 3+x PO 4-x N x (LiPON), etc., but are not limited to these.

[0065] Polymer electrolytes include, but are not limited to, polyethylene oxide (PEO), polypropylene oxide (PPO), and the like, and copolymers thereof.

[0066] The solid electrolyte may be glass or crystallized glass (glass ceramic). The solid electrolyte layer may contain, in addition to the solid electrolyte described above, a conductive additive, a binder, and the like, as needed. For details about the conductive additive and the binder, see the description of the positive electrode active material layer.

[0067] (Negative electrode active material layer) The negative electrode active material layer contains at least a negative electrode active material, and preferably further contains the above-mentioned solid electrolyte. In addition, depending on the intended use and purpose, it may contain additives used in negative electrode active material layers of solid-state batteries, such as a conductive additive and a binder.

[0068] The material of the negative electrode active material is not particularly limited, but is preferably capable of absorbing and releasing metal ions such as lithium ions. For example, the negative electrode active material may be, but is not limited to, an oxide-based negative electrode active material, an alloy-based negative electrode active material, a carbon material, or the like.

[0069] The oxide-based negative electrode active material is not particularly limited, and examples thereof include lithium titanate (LTO) particles.

[0070] The alloy-based negative electrode active material is not particularly limited, and examples thereof include Si alloy-based negative electrode active materials and Sn alloy-based negative electrode active materials. Examples of Si alloy-based negative electrode active materials include silicon, silicon oxide, silicon carbide, silicon nitride, and solid solutions thereof. The Si alloy-based negative electrode active material can also contain elements other than silicon, such as Fe, Co, Sb, Bi, Pb, Ni, Cu, Zn, Ge, In, Sn, Ti, etc. The Sn alloy-based negative electrode active material can also contain tin, tin oxide, tin nitride, or solid solutions thereof. The Sn alloy-based negative electrode active material can also contain elements other than tin, such as Fe, Co, Sb, Bi, Pb, Ni, Cu, Zn, Ge, In, Ti, Si, etc.

[0071] The carbon material is not particularly limited, and examples thereof include hard carbon, soft carbon, graphite, and the like.

[0072] For the solid electrolyte used in the negative electrode active material layer, the above description regarding the solid electrolyte layer can be referred to, and for the conductive additive and binder, the above description regarding the positive electrode active material layer can be referred to.

[0073] (negative electrode current collector layer) The conductive material used for the negative electrode current collector layer is not particularly limited, and may be, for example, SUS, aluminum, copper, nickel, iron, titanium, carbon, or the like, but is not limited to these.

[0074] The shape of the negative electrode current collector layer is not particularly limited, and examples thereof include foil, plate, mesh, etc. Among these, foil is preferred.

[0075] The negative electrode current collector layer may extend from an end face of the stacked battery unit, and multiple negative electrode current collector layers may be joined at the extending portion. The negative electrode current collector layer may extend from, for example, a second end face of the stacked battery unit.

[0076] The stacked battery of the present disclosure may further include elements other than the stacked battery unit, such as an exterior body, a current collecting terminal, and the like.

[0077] <Exterior body> The exterior body may be an exterior can, a laminate film, or the like.

[0078] When the exterior body is an exterior can, a battery case may be formed by the exterior can that houses the stacked battery and has an opening, and a sealing plate that seals the opening. The exterior can may be made of a metal material, such as stainless steel or aluminum.

[0079] When the exterior is a laminate film, the laminate film may house the battery stack. Specifically, the battery stack may be wound around the laminate film and housed in the laminate film. The laminate film may also be made up of first and second films, and in this case, the battery stack may be housed by being sandwiched between the first and second films from above and below in the stacking direction of the battery stack.

[0080] The laminate film may have a sealant resin layer, a metal layer, and a protective resin layer in this order along the thickness direction. Examples of materials for the sealant resin layer include olefin resins such as polypropylene (PP) and polyethylene (PE). Examples of materials for the metal layer include aluminum, aluminum alloys, and stainless steel. Examples of materials for the protective resin layer include polyethylene terephthalate (PET) and nylon.

[0081] The thickness of each layer constituting the laminate film and the laminate film itself are not particularly limited. The thickness of the sealant resin layer is, for example, 40 μm or more and 100 μm or less. The thickness of the metal layer is, for example, 30 μm or more and 60 μm or less. The thickness of the protective resin layer is, for example, 20 μm or more and 60 μm or less. The thickness of the laminate film is, for example, 80 μm or more and 250 μm or less.

[0082] <Collector terminal> The current collector terminals may be electrically connected to the current collector layers of the stacked battery. The material of the current collector terminals is not particularly limited as long as it has a current collecting function, and examples include aluminum, stainless steel, etc. The positive and negative electrode current collector terminals may be arranged to face a pair of end faces of the stacked battery. In particular, when the second end face has the above-mentioned inclined surface formed thereon, the positive electrode current collector terminal may be arranged to face the first end face, and the negative electrode current collector terminal may be arranged to face the second end face.

[0083] The shape, size, etc. of the current collecting terminal are not particularly limited.

[0084] When the battery of the present disclosure has current collector terminals, the laminate film may house the stacked battery together with the current collector terminals. Specifically, the laminate film may house the stacked battery together with the current collector terminals by winding the stacked battery and the current collector terminals. The laminate film may also be composed of first and second films, and in this case, the stacked battery and the current collector terminals may be housed by sandwiching the stacked battery and the current collector terminals between the first and second films from above and below in the stacking direction of the stacked battery.

[0085] Battery pack As illustrated in FIG. 7 , a battery pack 1 according to the present disclosure includes a plurality of stacked batteries 10. In the battery pack according to the present disclosure, 50% or more, 60% or more, 70% or more, 80% or more, 90% or more, 95% or more, or 99% or more of the plurality of stacked batteries are stacked batteries 10 according to the present disclosure, i.e., stacked batteries in which, at least the first end face of the outermost stacked battery unit 100, the end face is located more inward than the end faces of the adjacent stacked battery units. In such a battery pack, the proportion of stacked batteries that crack in the outermost stacked battery unit can be reduced. For the stacked battery 10 according to the present disclosure, the above description of the stacked battery according to the present disclosure can be referenced.

[0086] The number of stacked batteries in the battery pack of the present disclosure is not particularly limited, and may be 2 or more, 4 or more, 6 or more, 8 or more, or 10 or more, and may be 50 or less, 40 or less, 30 or less, or 20 or less.

[0087] The battery pack may further include elements other than the plurality of stacked batteries. For example, the battery pack may include an exterior housing that houses the plurality of stacked batteries. The material, shape, size, etc. of the exterior housing are not particularly limited, and any exterior housing commonly used for battery packs can be used. [Example]

[0088] Example <Provision of stacked battery units> A stack was obtained by forming an anode active material layer, a solid electrolyte layer, and a cathode active material layer in this order on the anode current collector layer so that, at the second end face, the tip of the anode active material layer was located inside the tip of the anode active material layer, the tip of the solid electrolyte layer was located inside the tip of the anode active material layer, and the tip of the cathode active material layer was located inside the tip of the solid electrolyte layer. The resulting stack was cut parallel to the stacking direction of the stack at the first end face. A cathode current collector layer was formed on the cathode active material layer of this stack to obtain a stacked battery unit. Note that, at the cut first end face, the positions of the end faces of each layer constituting the stacked battery unit were aligned with each other in the plane direction of the stacked battery unit. In contrast, at the uncut second end face, the end faces of the anode active material layer, solid electrolyte layer, and cathode active material layer all had inclined surfaces that approached the anode current collector layer toward their tips.

[0089] <Fabrication of stacked battery> Thirty battery units were stacked on top of each other so that the end face of the outermost battery unit was positioned 0.5 mm inward from the end faces of the adjacent battery units at the first end face of the battery. The thickness of the battery unit was 150 μm.

[0090] Comparative Example A stacked battery was fabricated in the same manner as in the example, except that 30 stacked battery units were stacked on top of each other so that the end face of the outermost stacked battery unit was positioned 0.5 mm outward from the end faces of the adjacent stacked battery units on the first end face of the stacked battery.

[0091] "evaluation" Each example of the stacked battery was evaluated for defects in the outermost stacked battery unit when pressed in the stacking direction. The pressure applied during pressing was 0.1 MPa and 1 MPa. A rating of ◯ was given when no defects occurred in the outermost stacked battery unit, △ when cracks occurred, and × when cracks occurred. The evaluation results are shown in Table 1.

[0092] [Table 1]

[0093] As shown in Table 1, in the stacked battery of the example, no defects occurred in the outermost stacked battery unit. [Explanation of symbols]

[0094] 1 battery pack 10. Stacked battery 100 stacked battery unit 100a slope 110 First current collector layer 120 First electrode active material layer 130 Solid electrolyte layer 140 Second electrode active material layer 150 Second current collector layer

Claims

1. A method for manufacturing a stacked battery, comprising the steps of: (a) providing a plurality of stacked battery units each having a first current collector layer, a first electrode active material layer, a solid electrolyte layer, a second electrode active material layer, and a second current collector layer in this order; (b) stacking the plurality of stacked battery units on one another such that, at least on a first end face of the stacked battery, the end face of the outermost stacked battery unit is positioned more inward than the end faces of the other adjacent stacked battery units;

2. 2. The method according to claim 1, wherein end faces of the first electrode active material layer, the solid electrolyte layer, and the second electrode active material layer in the plurality of stacked battery units all have inclined surfaces that approach the first current collector layer toward their tips, and the inclined surfaces are formed on a second end face of the stacked battery that faces the first end face.

3. 3. The method according to claim 2, wherein the inclined surface is formed because a length between opposing end faces of the second electrode active material layer is shorter than a length between opposing end faces of the first electrode active material layer.

4. 2. The method of claim 1, wherein in step (b), the plurality of stacked battery units are stacked on one another such that an end face of an outermost stacked battery unit at a second end face opposing the first end face of the stacked battery does not extend beyond an end face of another adjacent stacked battery unit.

5. The method of claim 1 , wherein in step (b), the position of the end face of the outermost stacked battery unit on at least the first end face of the stacked battery is determined by image processing.

6. A stacked battery in which a plurality of stacked battery units are stacked on top of each other, each of the plurality of stacked battery units includes a first current collector layer, a first electrode active material layer, a solid electrolyte layer, a second electrode active material layer, and a second current collector layer in this order; At least a first end face of the stacked battery, the end face of the outermost stacked battery unit is located more inward than the end faces of the other adjacent stacked battery units. Stacked battery.

7. 7. The stacked battery according to claim 6, wherein end faces of the first electrode active material layer, the solid electrolyte layer, and the second electrode active material layer in the stacked battery unit all have inclined surfaces that approach the first current collector layer toward their tips, and the inclined surfaces are formed on a second end face of the stacked battery that faces the first end face.

8. 7. The stacked battery according to claim 6, wherein an outermost stacked battery unit does not extend beyond an end face of another adjacent stacked battery unit at a second end face of the stacked battery that faces the first end face.

9. 7. The stacked battery according to claim 6, wherein, when viewed in a planar direction at least on the first end face of the stacked battery, a distance between an end face of an outermost stacked battery unit and an end face of another adjacent stacked battery unit is 0.1 mm or more and 1.0 mm or less.

10. A battery pack having a plurality of stacked batteries, A battery pack in which 50% or more of the plurality of stacked batteries are the stacked batteries according to any one of claims 6 to 9.

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