Method for manufacturing an electricity storage device

Abstract

To provide a technique which can obtain a power storage device having a wound electrode body with high productivity.SOLUTION: A manufacturing method of a power storage device (for example, battery) of one embodiment disclosed herein includes: winding step S2 of winding a positive electrode 22 and a negative electrode 24 through a separator 26 to manufacture a wound body 20A; and pressing step S3 of press-molding the wound body 20A after the winding step S2 to form flat wound electrode bodies 20a, 20b, 20c. In the winding step S2, the separator which has an adhesive layer 6 partially on at least one surface is used. The adhesive layer 6 includes: a first adhesive area 6A; and a second adhesive area 6B. A thickness T1 of the first adhesive area 6A is 1.5 times or more of a thickness T2 of the second adhesive area 6B. Furthermore, herein, the method further includes formation step S1 before the winding step S2.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a method for manufacturing an electricity storage device and a separator for an electricity storage device. Regarding. [Background technology]

[0002] For example, Japanese Patent No. 5328034 discloses a battery including a wound electrode assembly having a positive electrode, a negative electrode, and a separator, and a heat-resistant porous layer containing an adhesive resin on the surface of the separator. The document states that such a wound electrode assembly is produced by stacking a positive electrode and a negative electrode with a separator interposed between them, winding them, and crushing them into a flat shape. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5328034 Summary of the Invention [Problem to be solved by the invention]

[0004] However, according to the inventors' investigations, when the separator and electrode having the adhesive resin described above are strongly bonded to each other during winding, the relative positions of the separator and the electrode may not change appropriately when the wound body is crushed and deformed, which may result in distortion, wrinkles, or the like in the separator. On the other hand, if the separator does not have such an adhesive resin, there is a risk of misalignment in the wound body. This is undesirable from the viewpoint of productivity, etc. In other words, it was found that there is still room for improvement in terms of improving productivity in the manufacture of an electricity storage device (e.g., a battery) including a wound electrode body having an adhesive layer as described above.

[0005] The present disclosure has been made in view of the above circumstances, and its main purpose is to provide a technique that can produce an electricity storage device including a wound electrode body with high productivity. [Means for solving the problem]

[0006] To achieve this objective, the present disclosure provides a method for manufacturing an electric storage device including a flat wound electrode body formed by winding a strip-shaped first electrode and a strip-shaped second electrode with a strip-shaped separator interposed therebetween. The method includes a winding step of winding the first electrode and the second electrode with the separator interposed therebetween to produce a wound body, and a pressing step of, after the winding step, press-forming the wound body into a flat wound electrode body. In the winding step, a separator having a partial adhesive layer on at least one surface is used, and the adhesive layer includes a first adhesive region and a second adhesive region. The thickness T1 of the first adhesive region is 1.5 times or more the thickness T2 of the second adhesive region. As will be described in detail later, this method for manufacturing an electric storage device with such a configuration allows for highly productive production of an electric storage device including a wound electrode body.

[0007] Further, to achieve the above object, another manufacturing method for an electricity storage device disclosed herein is a manufacturing method for an electricity storage device including a flat wound electrode body in which a strip-shaped first electrode and a strip-shaped second electrode are wound with a strip-shaped separator interposed therebetween, the manufacturing method including: a winding step in which the first electrode and the second electrode are wound with the separator interposed therebetween to produce a wound body; and a pressing step in which, after the winding step, the wound body is press-molded into a flat wound electrode body, wherein the winding step uses a separator having a partial adhesive layer on at least one surface, the adhesive layer including a first adhesive region and a second adhesive region, the thickness of the first adhesive region being greater than the thickness of the second adhesive region. The manufacturing method for an electricity storage device disclosed herein is further provided, wherein the first adhesive region and the first electrode are bonded together in the winding step, and the second adhesive region and the first electrode are bonded together in the pressing step. Although details will be described later, a method for manufacturing an electricity storage device having such a configuration makes it possible to obtain an electricity storage device including a wound electrode body with high productivity.

[0008] From another aspect, the present disclosure provides a separator for an electricity storage device, the separator having an adhesive layer partially on at least one surface, the adhesive layer including a first adhesive region and a second adhesive region, and a thickness T1 of the first adhesive region being 1.5 times or more the thickness T2 of the second adhesive region. As will be described in detail later, a separator for an electricity storage device having such a configuration can produce an electricity storage device having a wound electrode body with high productivity. [Brief explanation of the drawings]

[0009] [Figure 1] 2 is a flowchart for explaining a method for manufacturing a battery according to the first and second embodiments. [Figure 2] 10A to 10C are explanatory diagrams for explaining a method for manufacturing a wound electrode body according to one embodiment. [Figure 3] FIG. 2 is a schematic diagram of a separator according to one embodiment after an adhesive layer is formed, as viewed from above. [Figure 4] FIG. 2 is a schematic diagram illustrating a wound body before a pressing process according to one embodiment. [Figure 5] FIG. 10 is a schematic diagram showing a wound body after a pressing process according to an embodiment. [Figure 6] FIG. 2 is a schematic diagram illustrating a state of a separator before a winding process according to one embodiment. [Figure 7] FIG. 2 is a schematic diagram illustrating the state of the separator after a winding step according to one embodiment. [Figure 8] FIG. 2 is a schematic diagram illustrating the state of the separator after a pressing process according to one embodiment. [Figure 9] FIG. 1 is a perspective view schematically illustrating a battery according to an embodiment. [Figure 10] FIG. 10 is a schematic longitudinal sectional view taken along line XX in FIG. 9. [Figure 11] FIG. 10 is a schematic longitudinal sectional view taken along line XI-XI in FIG. 9. [Figure 12] FIG. 10 is a schematic cross-sectional view taken along line XII-XII in FIG. 9. [Figure 13] FIG. 2 is a perspective view schematically showing a wound electrode body attached to a sealing plate. [Figure 14] FIG. 2 is a perspective view schematically showing a wound electrode body to which a positive electrode second current collecting portion and a negative electrode second current collecting portion are attached. [Figure 15] FIG. 2 is a schematic diagram showing the configuration of a wound electrode body of a battery according to one embodiment. [Figure 16] FIG. 2 is an enlarged view schematically illustrating an interface between a positive electrode, a negative electrode, and a separator according to one embodiment. [Figure 17] FIG. 10 is a view corresponding to FIG. 3 according to the third embodiment. [Figure 18] FIG. 18 is a schematic longitudinal sectional view taken along line XVIII-XVIII in FIG. 17. [Figure 19] FIG. 10 is a view corresponding to FIG. 3 according to the fourth embodiment. [Figure 20] FIG. 20 is a schematic longitudinal sectional view taken along line XX-XX in FIG. 19. [Figure 21] FIG. 10 is a view corresponding to FIG. 3 according to the fifth embodiment. [Figure 22] FIG. 22 is a schematic longitudinal sectional view taken along line XXII-XXII in FIG. 21. DETAILED DESCRIPTION OF THE INVENTION

[0010] Several embodiments of the technology disclosed herein will be described below with reference to the drawings. Naturally, the following description is not intended to limit the technology disclosed herein to the following embodiments. In the following drawings, components and parts that perform the same function are denoted by the same reference numerals. Furthermore, the dimensional relationships (length, width, thickness, etc.) in each drawing do not reflect actual dimensional relationships. Matters other than those specifically mentioned in this specification that are necessary for implementing the technology disclosed herein (e.g., the general configuration and manufacturing process of a battery that do not characterize the present invention) can be understood as design matters of a person skilled in the art based on prior art in the relevant field. The technology disclosed herein can be implemented based on the content disclosed in this specification and common technical knowledge in the relevant field. In this specification, the expression "A to B" indicating a range means "greater than A and less than B." It also encompasses the meanings of "greater than A" and "less than B."

[0011] In this specification, the term "electricity storage device" refers to a device that can be charged and discharged. Electricity storage devices include batteries such as primary batteries and secondary batteries (for example, non-aqueous electrolyte secondary batteries such as lithium ion secondary batteries, and nickel-metal hydride batteries), and capacitors (physical batteries) such as electric double layer capacitors. The electrolyte may be any of a liquid electrolyte (electrolytic solution), a gel electrolyte, and a solid electrolyte.

[0012] Hereinafter, the present technology will be described using as an example a method for manufacturing a lithium-ion secondary battery (hereinafter also simply referred to as "battery 100"), which is one embodiment of the power storage device disclosed herein. Note that the following description will be given of a case where the first electrode is a positive electrode 22 and the second electrode is a negative electrode 24, but the technology disclosed herein can also be applied to a case where the first electrode is a negative electrode 24 and the second electrode is a positive electrode 22, for example. The battery manufacturing method disclosed herein may further include other steps at any stage, and if a step is not described as essential, it can be deleted as appropriate. Furthermore, the order of the steps can be changed as long as the effects of the technology disclosed herein are achieved.

[0013] <Summary> The battery manufacturing method disclosed herein is a method for manufacturing a battery 100 including a flat wound electrode body (here, wound electrode bodies 20a, 20b, 20c) formed by winding a strip-shaped first electrode (here, positive electrode 22) and a strip-shaped second electrode (here, negative electrode 24) with a strip-shaped separator 26 (here, first separator 26S1 and second separator 26S2) interposed therebetween. The method also includes a winding step (step S2) of winding the first electrode (here, positive electrode 22) and the second electrode (here, negative electrode 24) with a separator 26 (here, first separator 26S1 and second separator 26S2) interposed therebetween to manufacture a wound body 20A, and a pressing step (step S3) of press-molding the wound body 20A to form a flat wound electrode body (here, wound electrode bodies 20a, 20b, 20c) after the winding step. In the above-mentioned winding process, a separator having a partial adhesive layer 6 on at least one surface is used, and the adhesive layer 6 includes a first adhesive region 6A and a second adhesive region 6B, and the thickness T1 of the first adhesive region 6A is greater than the thickness T2 of the second adhesive region 6B.

[0014] As described above, when the positional relationship between the electrode and the separator changes, for example, during the pressing process, if the electrode and the separator are strongly bonded, the positional relationship between the electrode and the separator may not change appropriately. This has been found to cause distortion, wrinkles, or the like in the separator. In contrast, according to the manufacturing method of the battery 100 described above, the electrode (here, the positive electrode 22) and the separator 26 are not strongly bonded to each other during the winding process, and only during the pressing process are they strongly bonded to each other. More specifically, during the winding process, the thicker first adhesive region 6A of the separator 26 comes into contact with the electrode, and during the pressing process, the thinner second adhesive region 6B that did not come into contact with the electrode during the winding process comes into contact with the electrode. With this configuration, the electrode and the separator 26 are not strongly bonded to each other during the winding process, and only during the pressing process are they strongly bonded to each other. Therefore, when the positional relationship between the electrode and the separator 26 changes during the pressing process, the positional relationship can be appropriately changed. This makes it possible to suitably prevent the separator 26 from being distorted or wrinkled. Furthermore, because the separator 26 having the first adhesive region 6A and the electrode (here, the positive electrode 22) are bonded during the winding process, it is possible to suitably prevent miswinding of the wound body 20A (for example, misalignment of the separator 26 and the electrode in the wound body 20A, which is particularly likely to occur when the wound body 20A is removed from the winding core 3). That is, the manufacturing method for the battery 100 described above makes it possible to produce the battery 100 including the wound electrode bodies 20a, 20b, and 20c with high productivity. Two specific embodiments will be described below as examples.

[0015] First Embodiment First, a method for manufacturing a battery according to the first embodiment will be described with reference to the flowchart in Fig. 1. First, the method for manufacturing a battery 100 according to the first embodiment is a method for manufacturing a battery 100 including a flat wound electrode body (here, wound electrode bodies 20a, 20b, 20c) in which a strip-shaped first electrode (here, positive electrode 22) and a strip-shaped second electrode (here, negative electrode 24) are wound with strip-shaped separators 26 (here, first separator 26S1 and second separator 26S2) interposed therebetween. As shown in FIG. 1, the manufacturing method of the battery 100 according to the first embodiment includes a winding step (step S2) in which a first electrode (here, a positive electrode 22) and a second electrode (here, a negative electrode 24) are wound with a separator 26 interposed therebetween to produce a wound body 20A, and a pressing step (step S3) in which, after the winding step, the wound body 20A is press-molded to form a flat wound electrode body (here, wound electrode bodies 20a, 20b, and 20c). In the winding step, a separator 26 is used that has a partial adhesive layer 6 on at least one surface. The adhesive layer 6 includes a first adhesive region 6A and a second adhesive region 6B. The thickness T1 of the first adhesive region 6A is 1.5 times or more the thickness T2 of the second adhesive region 6B.

[0016] As described above, when the positional relationship between the electrode and the separator changes, for example, during the pressing process, if the electrode and the separator are strongly bonded, the positional relationship between the electrode and the separator may not change appropriately. This has been found to cause distortion, wrinkles, and the like in the separator. In contrast, according to the manufacturing method of the battery 100 described above, the electrode (here, the positive electrode 22) and the separator 26 are not strongly bonded to each other during the winding process, and they are only strongly bonded to each other during the pressing process. More specifically, during the winding process, the thicker first adhesive region 6A of the separator 26 comes into contact with the electrode (see FIG. 7 ), and during the pressing process, the thinner second adhesive region 6B comes into contact with the electrode in addition to the first adhesive region 6A (see FIG. 8 ). With this configuration, the electrode and the separator 26 are not strongly bonded to each other during the winding process, and they are only strongly bonded to each other during the pressing process. Therefore, when the positional relationship between the electrode and separator 26 changes in the pressing step, the positional relationship can be appropriately changed. This makes it possible to suitably prevent the separator 26 from being distorted or wrinkled. Furthermore, because the separator 26 having the first adhesive region 6A and the electrode (here, the positive electrode 22) are bonded in the winding step, it is possible to suitably prevent the wound body 20A from being misaligned. That is, according to the manufacturing method of the battery 100 described above, the battery 100 including the wound electrode bodies 20a, 20b, and 20c can be obtained with high productivity.

[0017] The manufacturing method of the battery 100 according to this embodiment will be described below with reference to an electrode assembly manufacturing apparatus 1 that embodies the manufacturing method of the battery 100. The following describes a case where a dot-shaped adhesive layer 6 is disposed on one surface of the first separator 26S1 and the second separator 26S2. While the technology disclosed herein can also use separators 26 on which an adhesive layer 6 is previously disposed, the following describes a case where an adhesive layer 6 is formed on the surface of the separator 26 by an adhesive applicator 4. Accordingly, as shown in FIG. 1 , the manufacturing method of the battery 100 according to this embodiment further includes a forming step (step S1) before the winding step (step S2) described above. However, in other embodiments, this step may not be included.

[0018] FIG. 2 is a schematic diagram showing the configuration of an electrode assembly manufacturing apparatus 1 according to this embodiment. As shown in FIG. 2, the electrode assembly manufacturing apparatus 1 according to this embodiment includes a plurality of rollers 2 (six in this example), a winding core 3, an adhesive application section 4, and a drying section 5. In this embodiment, the electrode assembly manufacturing apparatus 1 also includes a cutter, a pressing jig, and a control device (not shown). Here, the cutter is a cutter that cuts the first separator 26S1 and the second separator 26S2. The pressing jig is a jig that presses the first separator 26S1 and the second separator 26S2 against the winding core 3. Each component of the electrode assembly manufacturing apparatus 1 has a required actuator, as appropriate. The control device is configured to control each component of the electrode assembly manufacturing apparatus 1 so that required operations are performed at predetermined timings according to a preset program. The control device may be embodied, for example, by a computer such as a microcontroller.

[0019] The positive electrode 22, the negative electrode 24, the first separator 26S1, and the second separator 26S2 are each prepared in a wound state around a reel (not shown) or the like. The positive electrode 22, the negative electrode 24, the first separator 26S1, and the second separator 26S2 are each transported along predetermined transport paths k1 to k4. Transport path k1 is a path along which the negative electrode 24 is fed from a reel (not shown) toward the winding core 3. Transport path k2 is a path along which the second separator 26S2 is fed from a reel (not shown) toward the winding core 3. Transport path k3 is a path along which the positive electrode 22 is fed from a reel (not shown) toward the winding core 3. Transport path k4 is a path along which the first separator 26S1 is fed from a reel (not shown) toward the winding core 3. The conveying paths k1 to k4 may be appropriately provided with dancer roll mechanisms for removing slack from the positive electrode 22, negative electrode 24, first separator 26S1, and second separator 26S2 being fed, tensioners for adjusting tension, and the like.

[0020] The plurality of rollers 2 are arranged on the transport paths k1 to k4 for the positive electrode 22, the negative electrode 24, the first separator 26S1, and the second separator 26S2, respectively. The plurality of rollers 2 are an example of a transport device. The plurality of rollers 2 are arranged at predetermined positions to define the respective transport paths k1 to k4. The positive electrode 22, the negative electrode 24, the first separator 26S1, and the second separator 26S2 are each transported by the plurality of rollers 2. Note that in this embodiment, the number of rollers 2 is six, but in other embodiments, the number of rollers 2 may be other than six.

[0021] The winding core 3 has a function of holding the positive electrode 22, negative electrode 24, first separator 26S1, and second separator 26S2 wound around its circumferential surface. Here, the winding core 3 is a substantially cylindrical member, but a flat winding core may be used when winding into a flat shape. Here, an undivided winding core is used as the winding core 3, but a winding core divided along the radial direction or a winding core with a variable diameter may also be used.

[0022] The winding core 3 may further have suction holes, grooves, and the like. The suction holes are holes for adsorbing, for example, the first separator 26S1 and the second separator 26S2 wound around the side circumferential surface. The suction holes may be circular or rectangular in plan view. Alternatively, the suction holes may be slit-shaped. The suction holes typically include a suction flow path formed inside the winding core 3 and communicating with the suction holes. The suction path is a flow path for creating negative pressure in the suction holes. The suction path may be configured, for example, to be appropriately connected to an external vacuum line to create negative pressure. The grooves can function as a receiving portion for the cutter blade to be lowered when the first separator 26S1 and the second separator 26S2 are cut. This prevents damage to the winding core or the cutter due to contact between the winding core 3 and the cutter blade.

[0023] The adhesive application unit 4 applies adhesive layer slurry to the surface of at least one of the separators 26 (here, the first separator 26S1 and the second separator 26S2) along the conveyance direction. The adhesive application unit 4 is configured to apply a desired amount of adhesive layer slurry to desired areas of the first separator 26S1 and the second separator 26S2. The adhesive layer slurry contains, for example, an adhesive layer binder (adhesive) as described below, and at least one of a solvent and a dispersion medium. Note that the term "slurry" may include ink, paste, etc.

[0024] The solvent contained in the adhesive layer slurry may be any liquid capable of dissolving the adhesive layer binder (adhesive). The dispersion medium contained in the adhesive layer slurry may be any liquid capable of dispersing the adhesive layer binder (adhesive). Examples of such solvents and dispersion media include water, aqueous solvents, organic solvents, and mixed solvents thereof. For example, from the viewpoint of reducing environmental impact, so-called aqueous solvents are preferably used. In this case, water or a mixed solvent mainly composed of water can be used. As the solvent component other than water constituting such a mixed solvent, one or more organic solvents (lower alcohols, lower ketones, etc.) that are uniformly miscible with water can be appropriately selected and used. For example, it is preferable to use an aqueous solvent in which 80% by mass or more (more preferably 90% by mass or more, and even more preferably 95% by mass or more) of the aqueous solvent is water. A particularly preferred example is an aqueous solvent that is essentially composed of water. The solvent for the adhesive layer slurry is not limited to so-called aqueous solvents, and may also be so-called organic solvents. Examples of organic solvents include alcohol-based solvents, ketone-based solvents, ester-based solvents, halogen-based solvents, hydrocarbon-based solvents, and nitrogen-containing solvents. These may be used alone or in combination. The boiling points of the solvent and dispersion medium are preferably, for example, about 50°C to 200°C or about 100°C to 150°C, from the viewpoint of facilitating removal of the solvent during drying after application of the adhesive layer slurry. If the boiling point is too low, the adhesive layer slurry may dry before application, impairing coating stability. Therefore, it is preferable to select the appropriate boiling point depending on the application method. The solvent / dispersion medium ratio in the adhesive layer slurry is adjusted appropriately depending on the application method. For example, in the case of application methods such as gravure printing and inkjet printing, the weight ratio is preferably about 50% to 99%, and more preferably about 80% to 95%. The adhesive layer binder (adhesive) may be dissolved or dispersed in the adhesive layer slurry. Furthermore, if the adhesive layer slurry is a solution in which the adhesive is dissolved, the adhesive may penetrate excessively into the heat-resistant layer 28 described below, so it is preferable that the adhesive layer slurry is a dispersion of the adhesive.Although not particularly limited, the content of the solvent and the dispersion medium in the adhesive layer slurry can be, for example, approximately 50 to 99% by mass (preferably, approximately 80 to 95% by mass) when the total adhesive layer slurry is 100% by mass.

[0025] Examples of the adhesive layer binder (adhesive) include acrylic resins, fluorine-based resins, rubber-based resins, urethane-based resins, silicone-based resins, and epoxy-based resins. These may be used alone or in combination of two or more. An example of the rubber-based resin is styrene butadiene rubber (SBR). Fluorine-based resins and acrylic resins are preferred because they have high flexibility and can more suitably exhibit adhesiveness to the electrode (here, the positive electrode 22). Examples of fluorine-based resins include polyvinylidene fluoride (PVdF) and polytetrafluoroethylene (PTFE). The type of the adhesive layer binder may be the same as or different from the heat-resistant layer binder described below. From the viewpoint of ease of handling, the adhesive layer binder preferably exhibits adhesiveness (adhesion) at room temperature (for example, about 25°C). On the other hand, the adhesive layer binder may exhibit adhesiveness (adhesion) by heating, pressure, or the like. Here, tackiness (adhesion) can mean, for example, that the peel strength in a 90° peel test based on JIS Z 0237:2009 is 0.00001 N / 20 mm to 0.1 N / 20 mm (preferably, 0.0001 N / 20 mm to 0.01 N / 20 mm). Although not particularly limited, the content of the adhesive layer binder in the adhesive layer slurry can be, for example, about 1 to 50 mass % (preferably, about 5 to 20 mass %) when the entire adhesive layer slurry is taken as 100 mass %.

[0026] Furthermore, for example, the adhesive layer binder (adhesive) may be a resin that bonds the electrode (here, the positive electrode 22) and the separator 26 at room temperature (e.g., about 25°C) and / or low pressure (e.g., 0.1 MPa or less, preferably 0.05 MPa or more). Such a resin preferably has a glass transition point at room temperature or lower, more preferably 0°C or lower, and even more preferably -10°C or lower. The glass transition point of such a resin may be, for example, -20°C or higher. Examples of such a resin include PVdF, SBR, and acrylic resins, which have low glass transition points as described above. Alternatively, the adhesive layer binder (adhesive) may be a resin that has low adhesiveness (tackiness) at room temperature but adheres the electrode (here, the positive electrode 22) to the separator 26 upon heating (for example, heating at 50°C or higher, 70°C or higher, preferably 150°C or lower, 100°C or lower) and / or pressure (for example, pressure of 0.1 MPa or higher, 1 MPa or higher, preferably 20 MPa or lower, 10 MPa or lower). Such resins preferably have a glass transition point at room temperature or higher, more preferably 30°C or higher, and even more preferably 40°C or higher, or 50°C or higher. The glass transition point of such resins may be, for example, 60°C or lower. Examples of such resins include PVdF, acrylic resins having high glass transition points, and epoxy resins, as described above. The glass transition point can be measured, for example, according to the method specified in JIS K 7121. Alternatively, a resin may be used that bonds the electrode (here, the positive electrode 22) and the separator 26 when irradiated with energy such as light.

[0027] Furthermore, although not particularly limited, the 90° peel strength between an electrode (here, the positive electrode 22) and a separator 26 having an adhesive layer 6 (first adhesive region 6A, second adhesive region 6B) may be, for example, 0.00001 N / 20 mm to 0.1 N / 20 mm (preferably 0.0001 N / 20 mm to 0.01 N / 20 mm). Such a 90° peel test can be measured, for example, by the following method. First, the separator 26 having the adhesive layer 6 and the electrode (here, the positive electrode 22) are each cut into a size of 2.0 cm in length and 7.0 cm in width, and the cut separator 26 and electrode are overlapped. Next, the separator 26 and the electrode are bent so that their angle is 90°. Then, using a tensile tester or the like, one side of the separator 26 opened at 90° and one side of the electrode are gripped and pulled at a pulling speed of 50 mm / min, and the strength when the two are peeled off is measured. In this way, the peel strength can be measured.

[0028] The adhesive layer slurry may contain one or more additives, such as known thickeners, surfactants, and inorganic fillers (e.g., alumina, titania, boehmite), as long as they do not impair the effects of the technology disclosed herein. When the adhesive layer slurry contains such an inorganic filler, the inorganic filler is preferably contained in an amount of, for example, about 5 to 20% by mass (preferably about 10 to 15% by mass) when the total mass of the adhesive layer slurry is taken as 100%. The viscosity of the adhesive layer slurry is not particularly limited as long as the effects of the technology disclosed herein are exhibited, but can be approximately 10 to 100 mPa·s (e.g., about 20 to 50 mPa·s). This viscosity can be measured, for example, using a commercially available viscometer.

[0029] As the adhesive application unit 4, various adhesive application units can be used, for example, inkjet printing, various intaglio printing machines such as gravure roll coaters and spray coaters, die coaters such as slit coaters, comma coaters and cap coaters (Capillary Coaters (CAP coaters), lip coaters, calendar machines, etc.

[0030] The drying section 5 removes at least one of the solvent and the dispersion medium from the adhesive layer slurry. The drying section 5 can volatilize at least one of the solvent and the dispersion medium from the separator 26. The drying method used by the drying section 5 is not particularly limited, and methods such as ventilation drying, heat drying, and vacuum drying can be used. For example, in the case of heat drying, the heating temperature may be about 40°C to 300°C (e.g., about 50°C to 200°C).

[0031] Next, a method for manufacturing the battery 100 according to this embodiment will be described. As described above, the method for manufacturing the battery 100 according to this embodiment includes a forming step (step S1), a winding step (step S2), and a pressing step (step S3). Each step will be described below.

[0032] (Step S1: Forming process) This process is performed before the winding process, and involves forming the adhesive layer on at least one of the surfaces of the separator 26. In this process, an adhesive layer slurry containing an adhesive and at least one of a solvent and a dispersion medium is disposed (applied) on at least one of the surfaces of the separator 26. As shown in FIG. 2, in this embodiment, the adhesive layer slurry is disposed on one surface of the first separator 26S1 and the second separator 26S2. Here, FIG. 3 is a schematic diagram of the separator 26 after forming the adhesive layer 6 according to this embodiment, viewed from above. As shown in FIG. 3, in this embodiment, a single continuous adhesive layer 6 having a first adhesive region 6A and a second adhesive region 6B is finally formed on the surface of the separator 26. Here, the adhesive layer 6 has a circular dot shape in a plan view of the separator 26, and has a first adhesive region 6A corresponding to the peripheral region and a second adhesive region 6B corresponding to the central region. Furthermore, the thickness of the first adhesive region 6A (length in the MD direction in FIG. 6) is different from the thickness of the second adhesive region (length in the MD direction in FIG. 6). For example, an adhesive applicator 4 having an inkjet printing function and a nozzle with a double diameter can be used to form a dot-shaped adhesive layer 6 on the surface of the separator 26. However, this is merely an example, and the adhesive layer slurry may be disposed on the surface of the separator 26 by other methods.

[0033] In a preferred embodiment, the method includes a removal step of removing at least one of the solvent and the dispersion medium from the adhesive layer slurry. As shown in FIG. 2, in this embodiment, the adhesive layer 6 disposed on the surface of the separator 26 in the formation step is dried by a drying unit 5. By removing the solvent and the dispersion medium, the amount of the solvent and the dispersion medium remaining in the adhesive layer 6 during the electrode assembly fabrication can be suitably reduced. Note that "removing at least one of the solvent and the dispersion medium from the adhesive layer slurry" can mean removing, for example, 70% by mass or more, 80% by mass or more, preferably 90% by mass or more, 95% by mass or more, or 99% by mass or more (particularly preferably 100% by mass) of the solvent and the dispersion medium, assuming that the total amount of the solvent and the dispersion medium in the adhesive layer slurry is 100% by mass. In the technology disclosed herein, it is not necessary to completely remove the solvent and the dispersion medium in this step; some of them may remain.

[0034] The forming process provides a separator 26 for an electrical storage device, the separator 26 having a partial adhesive layer 6 on at least one surface, the adhesive layer 6 including a first adhesive region 6A and a second adhesive region 6B, and the thickness T1 of the first adhesive region 6A being 1.5 times or more the thickness T2 of the second adhesive region 6B. As shown in FIG. 3 , in this embodiment, the adhesive layer 6 is disposed on one surface of the separator 26 (here, the first separator 26S1 and the second separator 26S2). With this configuration, the thicker first adhesive region 6A of the separator 26 comes into contact with the electrode (here, the positive electrode 22) in the winding process, and the thinner second adhesive region 6B comes into contact with the electrode (here, the positive electrode 22) in addition to the first adhesive region 6A in the pressing process. The electrode and the separator 26 are not strongly bonded to each other in the winding process, and it is only in the pressing process that they are strongly bonded to each other. Therefore, when the positional relationship between the electrode and the separator 26 changes during the pressing process, the positional relationship can be appropriately changed. This makes it possible to suitably prevent the separator 26 from being distorted or wrinkled. Furthermore, since the separator 26 having the first adhesive region 6A and the electrode (here, the positive electrode 22) are bonded during the winding process, it is possible to suitably prevent the wound body 20A from being misaligned. That is, the manufacturing method for the battery 100 described above makes it possible to produce the battery 100 including the wound electrode bodies 20a, 20b, and 20c with high productivity. The adhesive layer 6 being partially disposed on the surface of the separator 26 means that there are regions on the surface of the separator 26 where the adhesive layer 6 is not disposed. It is preferable that the adhesive layer 6 be patterned over a wide area of ​​the separator 26.

[0035] As shown in FIG. 3 , in this embodiment, the adhesive layers 6 are arranged in a dotted pattern in a plan view of the separator 26. Here, the dotted adhesive layers 6 (specifically, the outer shape of the first adhesive region 6A) have a circular shape in a plan view, but are not limited thereto. In other embodiments, the dotted adhesive layers 6 may have an elliptical, rectangular, polygonal, or a combination thereof in a plan view. In this embodiment, two adhesive layers 6 are arranged in each of the short sides of the strip-shaped separator 26 (Y direction in FIG. 3 ), but are not limited thereto. In other embodiments, one adhesive layer 6 may be arranged in each of the short sides of the separator 26 (Y direction in FIG. 3 ), or three or more adhesive layers 6 may be arranged in each of the short sides. In this embodiment, the second adhesive region 6B has a circular shape in a plan view of the separator 26, but is not limited thereto. In other embodiments, the second adhesive region 6B may have an elliptical, rectangular, or various other shapes. Alternatively, in other embodiments, the adhesive layer 6 may be arranged linearly in a plan view of the separator 26. For example, the third and fourth embodiments described below are examples of cases in which the adhesive layer is arranged linearly. As in this embodiment, the second adhesive region 6B may be arranged on the central side and the first adhesive region 6A on the outer periphery, or in other embodiments, the first adhesive region 6A may be arranged on the central side and the second adhesive region 6B on the outer periphery.

[0036] The first adhesive region 6A and the second adhesive region 6B of the adhesive layer 6 are preferably composed primarily of the adhesive layer binder described above. Here, "composed primarily of the adhesive layer binder" may mean that, when the entire adhesive layer 6 is taken as 100% by volume, the adhesive layer binder is contained in an amount of, for example, 50% by volume or more, 60% by volume or more, preferably 70% by volume or more, 80% by volume or more, more preferably 90% by volume or more, or 95% by volume or more (even 100% by volume). This allows the adhesive layer 6 to exhibit a predetermined adhesiveness to the electrode (here, the positive electrode 22). In a preferred embodiment, the resin constituting the first adhesive region 6A is composed primarily of the same component as the resin constituting the second adhesive region 6B. This configuration is preferable because it facilitates the formation of the adhesive layer 6 in the formation step. In another embodiment, the resin constituting the first adhesive region 6A may be composed primarily of different components than the resin constituting the second adhesive region 6B. Here, "the main component of the resin constituting the first adhesive region (second adhesive region)" may mean a resin that is contained in an amount of, for example, 50% by volume or more, 60% by volume or more, preferably 70% by volume or more, 80% by volume or more, more preferably 90% by volume or more, 95% by volume or more (or even 100% by volume) when the entire resin constituting the first adhesive region (second adhesive region) is taken as 100% by volume.

[0037] As described above, the first adhesive region 6A and the second adhesive region 6B of the adhesive layer 6 may contain other materials (for example, inorganic fillers such as alumina, titania, boehmite, etc.) in addition to the adhesive layer binder. When the adhesive layer 6 contains an inorganic filler, the inorganic filler is preferably contained in an amount of, for example, about 10 to 90 mass % (preferably about 20 to 80 mass %) when the entire adhesive layer 6 is taken as 100 mass %.

[0038] Furthermore, in a plan view, the ratio of the area of ​​the adhesive layer 6 on one side of the separator 26 to the area of ​​one side of the separator 26 (area of ​​the adhesive layer on one side of the separator / area of ​​one side of the separator) is not particularly limited as long as the effects of the technology disclosed herein are exhibited. The upper limit of this ratio is, for example, 0.8 or less, and from the viewpoint of the input / output characteristics of the battery 100, it is preferably 0.5 or less, and may be 0.3 or less, 0.2 or less, or 0.1 or less. The lower limit of this ratio is, for example, 0.001 or more, and from the viewpoint of suitably ensuring the adhesive strength between the separator 26 and the electrode and suitably suppressing the expansion of the thickness of the wound electrode body, it is preferably 0.005 or more, 0.01 or more, 0.03 or more, and more preferably 0.05 or more. In other words, for example, when (area of ​​the adhesive layer on one side of the separator / area of ​​one side of the separator) is 0.005 to 0.5, the above-mentioned effects can be suitably obtained.

[0039] Furthermore, in a plan view of the separator 26, the ratio of the area of ​​the first adhesive region 6A to the area of ​​the adhesive layer 6 (here, the total area of ​​the first adhesive region 6A and the second adhesive region 6B) (formation area of ​​the first adhesive region 6A / area of ​​the adhesive layer) is not particularly limited as long as the effects of the technology disclosed herein are exhibited. The lower limit of this ratio is, for example, 0.1 or more, and from the viewpoint of suitably suppressing winding slippage, etc., it is preferably 0.2 or more, and may be 0.3 or more, 0.4 or more, or 0.5 or more. The upper limit of this ratio is, for example, 0.9 or less, and from the viewpoint of suitably ensuring the adhesive force between the second adhesive region 6B and the electrode in the pressing step described below and suitably suppressing winding slippage, etc., it is preferably 0.8 or less, and may be 0.7 or less, or 0.6 or less. In other words, for example, when (formation area of ​​the first adhesive region 6A / area of ​​the adhesive layer) is 0.2 to 0.8, the above effects can be suitably obtained.

[0040] The diameter (diameter, corresponding to d in FIG. 3) of each dot-shaped adhesive layer 6 is not particularly limited as long as the effects of the technology disclosed herein are exhibited. The lower limit of d is, for example, 10 μm or more, and from the viewpoint of suitably ensuring the adhesive strength between the separator 26 and the electrode, it is preferably 50 μm or more, more preferably 75 μm or more, and particularly preferably 100 μm or more. The upper limit of d is, for example, 600 μm or less, and from the viewpoint of uniforming the charge / discharge reaction of the battery 100 and suppressing Li deposition, it is preferably 500 μm or less, more preferably 300 μm or less, or 200 μm or less. That is, in the winding step, the diameter (diameter) of each dot-shaped adhesive layer 6 is preferably, for example, 50 μm to 500 μm.

[0041] FIG. 6 is a schematic diagram illustrating a separator before a winding process according to one embodiment. FIG. 6 can also be considered a schematic longitudinal cross-sectional view taken along line VI-VI in FIG. 3. In this embodiment, adhesive layers 6 are disposed on the sides of the first separator 26S1 and the second separator 26S2 facing the positive electrode 22. However, for ease of explanation, FIG. 6 only illustrates the first separator 26S1 and the positive electrode 22. The same applies to the second separator 26S2 and the positive electrode 22. In the winding process (described later) (in other words, in the separator 26 used in the winding process, or after the formation process), the thickness of each dot-shaped adhesive layer 6 (the length in the MD direction in FIG. 6; corresponding to T1 in FIG. 6) is not particularly limited as long as the effects of the technology disclosed herein are exhibited. The lower limit of T1 is preferably 0.1 μm or more, more preferably 0.2 μm or more, and even more preferably 0.5 μm or more. The upper limit of T1 is preferably 10 μm or less, more preferably 5 μm or less, and more preferably 3 μm or less. That is, T1 is preferably within the range of 0.1 μm to 10 μm, for example. Setting T1 within the range is preferable from the viewpoints of ensuring the adhesiveness of the adhesive layer 6, making the charge / discharge reaction of the battery 100 uniform, and suppressing Li deposition.

[0042] As described above, the thickness T1 of the first adhesive region 6A is 1.5 times or more the thickness T2 of the second adhesive region 6B. That is, when comparing the thickness of at least a portion of the central region with the thickness of at least a portion of the peripheral region in the adhesive layer 6, the thickness is 1.5 times or more. From the viewpoint of more suitably obtaining the effects described above, the thickness T1 of the first adhesive region 6A is preferably 2 times or more, or may be 2.5 times or more, or may be 3 times or more the thickness T2 of the second adhesive region 6B. The thickness T1 of the first adhesive region 6A may be, for example, 5 times or less, or 4 times or less the thickness T2 of the second adhesive region 6B.

[0043] Although not particularly limited, the area of ​​the region surrounded by the periphery of one dot-shaped adhesive layer 6 in a plan view of the separator 26 is, for example, 0.5 mm 2 less than 0.25 mm, preferably 2 less than 0.1 mm, more preferably 2 The lower limit of the area of ​​one dot of adhesive layer 6 is, for example, 0.01 mm 2 or more, preferably 0.05 mm 2 That's all.

[0044] Although not particularly limited, the basis weight of the adhesive layer 6 on one side of the separator 26 is, for example, 0.005 g / m 2 or more, preferably 0.01 g / m 2 More preferably, it is 0.02 g / m or more. 2 The upper limit of the basis weight of the adhesive layer 6 is, for example, 2.0 g / m 2 and preferably 1.0 g / m 2 or less, more preferably 0.05 g / m 2 The "weight per unit area" refers to the value obtained by dividing the mass of the adhesive layer by the area of ​​the region where the adhesive layer is formed (mass of adhesive layer / area of ​​the region where the adhesive layer is formed).

[0045] (Step S2: Winding process) As described above, in this embodiment, a wound electrode assembly is manufactured as the electrode assembly in this step. In the winding step, a strip-shaped first electrode (here, the positive electrode 22), a strip-shaped second electrode (here, the negative electrode 24), and strip-shaped separators 26 (here, the first separator 26S1 and the second separator 26S2) are wound together to produce wound assembly 20A. As shown in FIG. 2 , in this embodiment, the negative electrode 24, the second separator 26S2, the positive electrode 22, and the first separator 26S1 are transported to the winding core 3 via transport paths k1 to k4, respectively, and wound around winding core 3 to produce wound assembly 20A. While a cylindrical winding core 3 is used here, this is not limiting and a flat one may also be used, for example. The cross-sectional shape of wound assembly 20A may be flat as in this embodiment, or may be other shapes such as a perfect circle, an ellipse, or a track shape. Each sheet is wound so that only the positive electrode tab 22t of the positive electrode 22 protrudes from one side edge in the width direction Y (the left side in FIG. 15 ), and only the negative electrode tab 24t of the negative electrode 24 protrudes from the other side edge (the right side in FIG. 15 ). The number of windings is preferably adjusted appropriately taking into consideration the performance and manufacturing efficiency of the target battery 100. In some embodiments, the number of windings can be 20 or more, or 30 or more. The temperature in the winding step is preferably 50°C or less, more preferably 40°C or less, and even more preferably 35°C or less. The winding step is preferably performed at 10°C or more. The first adhesive region 6A and the second adhesive region 6B can be, for example, adhesive (adhesive) under the temperature conditions in the winding step.

[0046] (Step S3: Pressing process) As described above, in this process, after the winding process, the wound body 20A is press-formed to form the flat wound electrode body 20a. This configuration allows for more favorable adhesion between the separator 26 and the electrodes. Furthermore, this configuration effectively prevents an increase in the thickness of the wound electrode body 20a (20b, 20c) after the pressing process, thereby favorably improving the ease of inserting the wound electrode body into the case 10. In this embodiment, the wound body 20A obtained in the winding process is press-formed to form the flat wound electrode body 20a. FIG. 4 is a schematic diagram showing the wound body 20A before the pressing process according to this embodiment. FIG. 5 is a schematic diagram showing the wound body 20A after the pressing process according to this embodiment. First, as shown in FIG. 4, the wound body 20A is placed in a press machine 200 having a pair of opposing pressing surfaces, and then pressed in the direction of the outline arrow to obtain the flat wound electrode body 20a. Here, the pressing pressure can be, for example, within a range of 0.1 MPa to 20 MPa (preferably, 5 MPa to 10 MPa). The pressing can be unheated pressing, heated pressing, or both. In the case of heated pressing, the heating temperature can be, for example, within a range of 50°C to 100°C (preferably, 70°C to 90°C). As shown in FIG. 11 , the electrode body 20a in a flat shape after press molding has a pair of curved portions 20r whose outer surfaces are curved and a flat portion 20f whose outer surface is flat and connects the pair of curved portions 20r. Furthermore, a positive electrode tab group 23 in which positive electrode tabs 22t are stacked is formed at one end in the width direction Y of the wound electrode body 20a in a flat shape after press molding, and a negative electrode tab group 25 in which negative electrode tabs 24t are stacked is formed at the other end. A core portion in which the positive electrode active material layer 22a and the negative electrode active material layer 24a face each other is formed at the center of the width direction Y of the wound electrode body.

[0047] In a preferred embodiment, the forming step is performed immediately before the winding step. After the forming step, it is preferable to continuously perform the winding step without winding the separator 26 onto a separator roll or the like (in other words, with the separator 26 unfolded). As shown in FIG. 2 , in this embodiment, the positive electrode 22, the negative electrode 24, and the separator 26 (here, the first separator 26S1 and the second separator 26S2) are wound together to produce the wound body 20A. The adhesive layer 6 is disposed and formed immediately before the winding step. This configuration is preferable because side reactions are less likely to occur in the adhesive layer 6 and dust and the like are less likely to adhere to the adhesive layer 6. The time from the forming step to the winding step is, for example, 60 minutes or less (preferably less than 60 minutes), preferably 30 minutes or less, 20 minutes or less (e.g., less than 20 minutes), more preferably 10 minutes or less, and particularly preferably 5 minutes or less (e.g., less than 5 minutes). Furthermore, the shortest distance from the position where the forming step is carried out (for example, the position of adhesive application section 4 in FIG. 2) to the position where the winding step is carried out (for example, the position of winding core 3 in FIG. 2) is, for example, 50 m or less (preferably less than 50 m), preferably 30 m or less, more preferably 10 m or less (for example, less than 10 m), and particularly preferably 5 m or less, 3 m or less (for example, less than 3 m). However, this is not limited to these.

[0048] In a preferred embodiment, the separator 26 and the first electrode (here, the positive electrode 22) are bonded by the first adhesive region 6A in the winding step, and the second adhesive region 6B and the first electrode (here, the positive electrode 22) are bonded with a force weaker than the adhesive force between the first adhesive region 6A and the first electrode (here, the positive electrode 22), or the second adhesive region 6B and the first electrode (here, the positive electrode 22) are not bonded. Then, in the pressing step, the second adhesive region 6B and the first electrode (here, the positive electrode 22) are bonded more strongly than they were before the pressing step. This configuration makes it possible to preferably obtain the effects disclosed herein. While not particularly limited, when the second adhesive region 6B and the first electrode are bonded with a force weaker than the adhesive force between the first adhesive region 6A and the first electrode in the winding step, the adhesive force (peel strength) of the first adhesive region 6A to the first electrode when a pressing force (for example, about 0.01 MPa to 0.1 MPa) is applied in the winding step can be, for example, 0.00001 N / 20 mm to 0.1 N / 20 mm (preferably, 0.0001 N / 20 mm to 0.01 N / 20 mm).Furthermore, the adhesive force (peel strength) of the second adhesive region 6B to the first electrode (here, the positive electrode 22) can be, for example, 0 N / 20 mm to 0.00001 N / 20 mm (preferably, 0 N / 20 mm to 0.000001 N / 20 mm). In the winding step, the difference in adhesive strength (peel strength) between the first adhesive region 6A and the second adhesive layer 1B to the first electrode can be, for example, 0.00001 N / 20 mm to 0.1 N / 20 mm (preferably, 0.0001 N / 20 mm to 0.01 N / 20 mm). Furthermore, although not particularly limited, the difference in peel strength between the second adhesive region 6B before and after the pressing step can be, for example, 0.00001 N / 20 mm to 0.1 N / 20 mm (preferably, 0.0001 N / 20 mm to 0.06 N / 20 mm).

[0049] Although not shown, in this embodiment, a separator 26 is disposed on the outermost surface of the wound electrode assembly 20a after the pressing process, and a stop tape is attached to the end of the winding of the separator 26 to maintain the shape of the wound electrode assembly 20a. Any conventional stop tape used for wound electrodes can be used without particular limitation. Although not shown, in this embodiment, the end of the winding of the positive electrode 22 is disposed at the curved portion 20r of the electrode assembly 20a. In this manner, the electrode assemblies 20a, 20b, and 20c according to this embodiment can be fabricated.

[0050] Next, an electrode assembly 20 integrated with the sealing plate 14 is produced. Specifically, first, as shown in Fig. 13, three wound electrode bodies 20a each having a positive electrode second current collecting portion 52 and a negative electrode second current collecting portion 62 attached thereto are prepared, and are arranged side by side in the short side direction X as wound electrode bodies 20a, 20b, and 20c. At this time, the wound electrode bodies 20a, 20b, and 20c may all be arranged in parallel such that the positive electrode second current collecting portion 52 is arranged on one side in the long side direction Y (the left side in Fig. 13) and the negative electrode second current collecting portion 62 is arranged on the other side in the long side direction Y (the right side in Fig. 13).

[0051] Next, as shown in FIG. 12 , with the multiple positive electrode tabs 22t bent, the positive electrode first current collecting portion 51 fixed to the sealing plate 14 is joined to the positive electrode second current collecting portion 52 of the wound electrode bodies 20a, 20b, and 20c. Also, with the multiple negative electrode tabs 24t bent, the negative electrode first current collecting portion 61 fixed to the sealing plate 14 is joined to the negative electrode second current collecting portion 62 of the wound electrode bodies 20a, 20b, and 20c. Examples of joining methods that can be used include ultrasonic welding, resistance welding, and laser welding. Welding using high-energy beams such as lasers is particularly preferred. By this welding process, joints are formed in the recesses of the positive electrode second current collecting portion 52 and the negative electrode second current collecting portion 62.

[0052] Next, the combined product prepared as described above is housed in the internal space of the exterior body 12. Specifically, first, an insulating resin sheet made of a resin material such as polyethylene (PE) is folded into a bag or box shape to prepare an electrode assembly holder 29. Next, the electrode assembly group 20 is housed in the electrode assembly holder 29. Then, the electrode assembly group 20 covered by the electrode assembly holder 29 is inserted into the exterior body 12. If the weight of the electrode assembly group 20 is heavy, approximately 1 kg or more, for example 1.5 kg or more, or even 2 to 3 kg, it is advisable to insert the electrode assembly group 20 into the exterior body 12 with the long side wall 12b of the exterior body 12 positioned so as to intersect with the direction of gravity (with the exterior body 12 facing sideways).

[0053] Finally, the sealing plate 14 is joined to the edge of the opening 12h of the exterior body 12 to seal the opening 12h. The exterior body 12 and the sealing plate 14 are then welded together. The exterior body 12 and the sealing plate 14 can be welded together by, for example, laser welding. Thereafter, the electrolyte is injected through the liquid inlet 15, and the liquid inlet 15 is closed with a sealing member 15a to hermetically seal the battery 100. In this manner, the battery 100 can be manufactured.

[0054] <Second embodiment> Next, a method for manufacturing a battery according to the second embodiment will be described with reference to the flowchart in Fig. 1. First, the method for manufacturing a battery 100 according to the second embodiment is a method for manufacturing a battery 100 including a flat wound electrode body (here, wound electrode bodies 20a, 20b, 20c) in which a strip-shaped first electrode (here, positive electrode 22) and a strip-shaped second electrode (here, negative electrode 24) are wound with strip-shaped separators 26 (here, first separator 26S1 and second separator 26S2) interposed therebetween. As shown in FIG. 1, the method for manufacturing a battery 100 according to the second embodiment includes a winding step (step S2) in which a first electrode (here, a positive electrode 22) and a second electrode (here, a negative electrode 24) are wound with a separator 26 interposed therebetween to produce a wound body 20A, and a pressing step (step S3) in which, after the winding step, the wound body 20A is press-molded to form a flat wound electrode body (here, wound electrode bodies 20a, 20b, and 20c). In the winding step, a separator 26 is used that has a partial adhesive layer 6 on at least one surface. The adhesive layer 6 includes a first adhesive region 6A and a second adhesive region 6B. The thickness T1 of the first adhesive region 6A is greater than the thickness T2 of the second adhesive region 6B. Furthermore, the first adhesive region 6A and the first electrode (here, the positive electrode 22) are adhered together, and in the pressing step, the second adhesive region 6B and the first electrode (here, the positive electrode 22) are adhered together.

[0055] As described above, in the winding step, the first adhesive region 6A and the first electrode (here, the positive electrode 22) are bonded together (see FIG. 7 ). In the pressing step, in addition to the first adhesive region 6A, the second adhesive region 6B and the first electrode (here, the positive electrode 22) are also bonded together (see FIG. 8 ). This allows the electrode and the separator 26 to be in a state where they are not strongly bonded together in the winding step, and allows them to be strongly bonded together only in the pressing step. Therefore, when the positional relationship between the electrode and the separator 26 changes in the pressing step, this positional relationship can be appropriately changed. This makes it possible to suitably prevent distortion, wrinkles, and the like from occurring in the separator 26. Furthermore, because the separator 26 having the first adhesive region 6A and the electrode (here, the positive electrode 22) are bonded together in the winding step, it is possible to suitably prevent misalignment of the wound body 20A. That is, according to the manufacturing method of the battery 100 described above, the battery 100 including the wound electrode bodies 20a, 20b, and 20c can be obtained with high productivity.

[0056] Regarding the manufacturing method of the battery according to the second embodiment, the various steps, the shape and arrangement of the adhesive layer, and other details can be appropriately referred to the matters explained in the first embodiment section above.

[0057] <Battery configuration> Next, an example of a battery obtained by the battery manufacturing method disclosed herein will be described.

[0058] FIG. 9 is a perspective view of the battery 100. FIG. 10 is a schematic longitudinal cross-sectional view taken along line XX in FIG. 9. FIG. 11 is a schematic longitudinal cross-sectional view taken along line XI-XI in FIG. 9. FIG. 12 is a schematic transverse cross-sectional view taken along line XII-XII in FIG. 9. In the following description, the symbols L, R, F, Rr, U, and D in the drawings represent left, right, front, rear, top, and bottom, and the symbols X, Y, and Z in the drawings represent the short side direction of the battery 100, the long side direction perpendicular to the short side direction, and the up-down direction, respectively. However, these directions are merely used for convenience of description and do not limit the installation form of the battery 100 in any way.

[0059] As shown in Fig. 10, the battery 100 includes a battery case (case) 10 and an electrode assembly 20. In addition to the battery case 10 and the electrode assembly 20, the battery 100 according to this embodiment also includes a positive electrode terminal 30, a positive electrode external conductive member 32, a negative electrode terminal 40, a negative electrode external conductive member 42, an external insulating member 92, a positive electrode current collector 50, a negative electrode current collector 60, a positive electrode internal insulating member 70, and a negative electrode internal insulating member 80. Although not shown, the battery 100 according to this embodiment further includes an electrolyte. The battery 100 here is a lithium-ion secondary battery.

[0060] The battery case 10 is a housing that houses the electrode assembly 20. Here, the battery case 10 has a flat, bottomed, rectangular parallelepiped (rectangular) outer shape. The material of the battery case 10 may be the same as that conventionally used, and is not particularly limited. The battery case 10 is preferably made of a metal having a predetermined strength. Examples of metal materials that constitute the battery case 10 include aluminum, aluminum alloys, iron, and iron alloys.

[0061] The battery case 10 includes an exterior body 12, a sealing plate 14, and a gas release valve 17. The exterior body 12 is a flat, rectangular container with an opening 12h on one side. Specifically, as shown in FIG. 9 , the exterior body 12 includes a substantially rectangular bottom wall 12a, a pair of second side walls 12c extending upward in a U-direction from a short side of the bottom wall 12a and facing each other, and a pair of first side walls 12b extending upward in a U-direction from a long side of the bottom wall 12a and facing each other. The area of ​​the second side walls 12c is smaller than the area of ​​the first side walls 12b. The opening 12h is formed on the upper surface of the exterior body 12, which is surrounded by the pair of first side walls 12b and the pair of second side walls 12c. The sealing plate 14 is attached to the exterior body 12 so as to close the opening 12h of the exterior body 12. The sealing plate 14 is a substantially rectangular plate material in a plan view. The sealing plate 14 faces the bottom wall 12a of the exterior body 12. The battery case 10 is formed by joining (e.g., welding) the sealing plate 14 to the periphery of the opening 12h of the exterior body 12. The sealing plate 14 can be joined by welding, for example, laser welding. Specifically, each of the pair of second side walls 12c is joined to a short side of the sealing plate 14, and each of the pair of first side walls 12b is joined to a long side of the sealing plate 14.

[0062] As shown in FIGS. 9 and 10 , the gas release valve 17 is formed on the sealing plate 14. The gas release valve 17 is configured to open when the pressure inside the battery case 10 reaches or exceeds a predetermined value, thereby releasing gas inside the battery case 10. In this embodiment, the gas release valve 17 is a substantially circular recess in plan view that is recessed from the outer surface of the sealing plate 14 toward the electrode assembly 20. A thin-walled portion that is thinner than the thickness of the sealing plate 14 is formed on the bottom surface of the gas release valve 17. The thin-walled portion of this gas release valve 17 ruptures when the internal case pressure reaches or exceeds a predetermined value. This allows gas inside the battery case 10 to be released to the outside, thereby reducing the increased internal case pressure.

[0063] In addition to the gas release valve 17, the sealing plate 14 is also provided with a liquid inlet 15 and two terminal insertion holes 18 and 19. The liquid inlet 15 is connected to the internal space of the exterior body 12 and is an opening provided for injecting electrolyte during the manufacturing process of the battery 100. The liquid inlet 15 is sealed with a sealing member 15a. A blind rivet, for example, is suitable as the sealing member 15a. This allows the sealing member 15a to be firmly fixed inside the battery case 10. The terminal insertion holes 18 and 19 are formed at both ends of the sealing plate 14 in the long side direction Y. The terminal insertion holes 18 and 19 penetrate the sealing plate 14 in the up-down direction Z. As shown in FIG. 9 , a positive terminal 30 is inserted into the terminal insertion hole 18 on one side (left side) in the long side direction Y. A negative terminal 40 is inserted into the terminal insertion hole 19 on the other side (right side) in the long side direction Y.

[0064] FIG. 13 is a perspective view schematically showing a wound electrode body attached to a sealing plate 14. In this embodiment, a plurality of (here, three) wound electrode bodies 20a, 20b, and 20c are housed inside the battery case 10. The number of wound electrode bodies housed inside one battery case 10 is not particularly limited and may be one or two or more (plural). As shown in FIG. 10, a positive electrode current collector 50 is disposed on one side of the long side direction Y of each wound electrode body (the left side in FIG. 10), and a negative electrode current collector 60 is disposed on the other side of the long side direction Y (the right side in FIG. 10). The wound electrode bodies 20a, 20b, and 20c are connected in parallel. However, the wound electrode bodies 20a, 20b, and 20c may also be connected in series. Each wound electrode body is housed inside the exterior body 12 of the battery case 10 while being covered with an electrode body holder 29 (see FIG. 11) made of a resin sheet.

[0065] Fig. 14 is a perspective view that schematically shows the wound electrode body 20a. Fig. 15 is a schematic diagram that shows the configuration of the wound electrode body 20a. Here, in Fig. 15, for ease of viewing, the adhesive layer 6 formed on the surface of the separator 26 is omitted. Note that, although the wound electrode body 20a will be described in detail below as an example, the wound electrode bodies 20b and 20c can also have a similar configuration.

[0066] 15, the wound electrode body 20a has a positive electrode 22, a negative electrode 24, and a separator 26. In this example, the wound electrode body 20a is a wound electrode body in which a strip-shaped positive electrode 22 and a strip-shaped negative electrode 24 are stacked with two strip-shaped separators 26 interposed therebetween, and wound around a winding axis WL.

[0067] The wound electrode body 20a has a flat shape. The wound electrode body 20a is disposed inside the exterior body 12 with the winding axis WL oriented substantially parallel to the long side direction Y. Specifically, as shown in Fig. 11, the wound electrode body 20a has a pair of curved portions (R portions) 20r that face the bottom wall 12a and the sealing plate 14 of the exterior body 12, and a flat portion 20f that connects the pair of curved portions 20r and faces the second side wall 12c of the exterior body 12. The flat portion 20f extends along the second side wall 12c.

[0068] As shown in FIG. 15, the positive electrode 22 includes a positive electrode current collector 22c, a positive electrode active material layer 22a, and a positive electrode protective layer 22p adhered to at least one surface of the positive electrode current collector 22c. However, the positive electrode protective layer 22p is not essential and may be omitted in other embodiments. The positive electrode current collector 22c is strip-shaped. The positive electrode current collector 22c is made of a conductive metal such as aluminum, an aluminum alloy, nickel, or stainless steel. In this example, the positive electrode current collector 22c is a metal foil, specifically, an aluminum foil.

[0069] A plurality of positive electrode tabs 22t are provided at one end of positive electrode current collector 22c in long side direction Y (the left end in FIG. 15). The plurality of positive electrode tabs 22t are provided at intervals (intermittently) along the longitudinal direction of band-shaped positive electrode 22. The plurality of positive electrode tabs 22t protrude outward beyond separator 26 toward one axial side of winding axis WL (the left side in FIG. 15). Note that positive electrode tabs 22t may be provided on the other axial side of winding axis WL (the right side in FIG. 15) or on both axial sides of winding axis WL. Positive electrode tabs 22t are part of positive electrode current collector 22c and are made of metal foil (aluminum foil). However, positive electrode tabs 22t may be separate members from positive electrode current collector 22c. In at least a part of the positive electrode tab 22t, the positive electrode active material layer 22a and the positive electrode protective layer 22p are not formed, and a region where the positive electrode current collector 22c is exposed is formed.

[0070] As shown in FIG. 12 , the positive electrode tabs 22t are stacked at one axial end of the winding axis WL (the left end in FIG. 12 ) to form a positive electrode tab group 23. The positive electrode tabs 22t are each bent so that their outer ends are aligned. This improves the fitment into the battery case 10 and enables the battery 100 to be miniaturized. As shown in FIG. 10 , the positive electrode tab group 23 is electrically connected to the positive electrode terminal 30 via a positive electrode current collector 50. Specifically, the positive electrode tab group 23 and the positive electrode second current collector 52 are connected at a connection J (see FIG. 12 ). The positive electrode second current collector 52 is electrically connected to the positive electrode terminal 30 via a positive electrode first current collector 51. The size of the positive electrode tabs 22t (the length along the long side direction Y and the width perpendicular to the long side direction Y; see FIG. 15 ) can be appropriately adjusted, for example, by their formation positions, taking into account the state of connection to the positive electrode current collector 50. Here, the sizes of the plurality of positive electrode tabs 22t are different from one another so that the outer ends are aligned when bent.

[0071] As shown in FIG. 15, the positive electrode active material layer 22a is provided in a strip shape along the longitudinal direction of the strip-shaped positive electrode current collector 22c. The positive electrode active material layer 22a contains a positive electrode active material (e.g., a lithium transition metal composite oxide such as a lithium nickel cobalt manganese composite oxide) capable of reversibly absorbing and releasing charge carriers. When the total solid content of the positive electrode active material layer 22a is taken as 100 mass%, the positive electrode active material may account for approximately 80 mass% or more, typically 90 mass% or more, for example, 95 mass% or more. The positive electrode active material layer 22a may contain optional components other than the positive electrode active material, such as a conductive material, a binder, various additives, etc. Examples of the conductive material include a carbon material such as acetylene black (AB). Examples of the binder include polyvinylidene fluoride (PVdF).

[0072] As shown in FIG. 15, the positive electrode protective layer 22p is provided at the boundary between the positive electrode collector 22c and the positive electrode active material layer 22a in the long side direction Y. Here, the positive electrode protective layer 22p is provided at one end (the left end in FIG. 15) of the positive electrode collector 22c in the axial direction of the winding axis WL. However, the positive electrode protective layer 22p may also be provided at both axial ends. The positive electrode protective layer 22p is provided in a strip shape along the positive electrode active material layer 22a. The positive electrode protective layer 22p contains an inorganic filler (e.g., alumina). When the entire solid content of the positive electrode protective layer 22p is taken as 100 mass%, the inorganic filler may account for approximately 50 mass% or more, typically 70 mass% or more, for example, 80 mass% or more. The positive electrode protective layer 22p may also contain optional components other than the inorganic filler, such as a conductive material, a binder, and various additive components. The conductive material and binder may be the same as those exemplified as those that may be contained in the positive electrode active material layer 22a.

[0073] As shown in Fig. 15, the negative electrode 24 includes a negative electrode current collector 24c and a negative electrode active material layer 24a fixed to at least one surface of the negative electrode current collector 24c. The negative electrode current collector 24c is strip-shaped. The negative electrode current collector 24c is made of a conductive metal such as copper, a copper alloy, nickel, or stainless steel. In this example, the negative electrode current collector 24c is a metal foil, specifically a copper foil.

[0074] A plurality of negative electrode tabs 24t are provided at one axial end (the right end in FIG. 15 ) of the winding axis WL of the negative electrode current collector 24c. The plurality of negative electrode tabs 24t are provided at intervals (intermittently) along the longitudinal direction of the strip-shaped negative electrode 24. Each of the plurality of negative electrode tabs 24t protrudes outward from the separator 26 toward one axial end (the right end in FIG. 15 ). However, the negative electrode tab 24t may be provided at the other axial end (the left end in FIG. 15 ) or at each of both axial end portions. The negative electrode tab 24t is part of the negative electrode current collector 24c and is made of metal foil (copper foil). However, the negative electrode tab 24t may be a separate member from the negative electrode current collector 24c. At least a portion of the negative electrode tab 24t has an area where the negative electrode active material layer 24a is not formed and the negative electrode current collector 24c is exposed.

[0075] As shown in FIG. 12 , the negative electrode tabs 24t are stacked at one axial end (the right end in FIG. 12 ) to form a negative electrode tab group 25. The negative electrode tab group 25 is preferably provided at a position symmetrical to the positive electrode tab group 23 in the axial direction. The negative electrode tabs 24t are each bent so that their outer ends are aligned. This improves the fitment into the battery case 10, enabling the battery 100 to be miniaturized. As shown in FIG. 10 , the negative electrode tab group 25 is electrically connected to the negative electrode terminal 40 via the negative electrode current collector 60. Specifically, the negative electrode tab group 25 and the negative electrode second current collector 62 are connected at a connection part J (see FIG. 12 ). The negative electrode second current collector 62 is electrically connected to the negative electrode terminal 40 via the negative electrode first current collector 61. As with the multiple positive electrode tabs 22t, the multiple negative electrode tabs 24t here have different sizes so that the outer edges of the tabs are aligned when bent.

[0076] As shown in FIG. 15, the negative electrode active material layer 24a is provided in a strip shape along the longitudinal direction of a strip-shaped negative electrode current collector 24c. The negative electrode active material layer 24a contains a negative electrode active material (e.g., a carbon material such as graphite) that can reversibly store and release charge carriers. When the total solid content of the negative electrode active material layer 24a is taken as 100 mass%, the negative electrode active material may account for approximately 80 mass% or more, typically 90 mass% or more, for example, 95 mass% or more. The negative electrode active material layer 24a may contain optional components other than the negative electrode active material, such as a binder, a dispersant, and various additives. Examples of the binder that can be used include rubbers such as styrene butadiene rubber (SBR). Examples of the dispersant that can be used include celluloses such as carboxymethyl cellulose (CMC).

[0077] As shown in FIGS. 15 and 3, the separator 26 is a strip-shaped member. The separator 26 is an insulating sheet having a plurality of fine through-holes formed therein through which charge carriers can pass. The width of the separator 26 is greater than the width of the negative electrode active material layer 24a. By interposing the separator 26 between the positive electrode 22 and the negative electrode 24, contact between the positive electrode 22 and the negative electrode 24 is prevented and charge carriers (e.g., lithium ions) can be transferred between the positive electrode 22 and the negative electrode 24. Although not particularly limited, the thickness of the separator 26 (the length in the stacking direction MD in FIG. 16; the same applies hereinafter) is preferably 3 μm or more, more preferably 5 μm or more. The thickness of the separator 26 is preferably 25 μm or less, more preferably 18 μm or less, and even more preferably 14 μm or less.

[0078] Here, two separators 26 are used for one wound electrode body 20a. Preferably, two separators 26, i.e., a first separator and a second separator, are used for one wound electrode body 20a as in this embodiment. Here, the two separators each have the same configuration, but they may be different. In other embodiments, a single separator may be used, and for example, when manufacturing a laminated electrode body as the electrode body, a strip-shaped separator folded zigzag may be used.

[0079] 16 is an enlarged view schematically illustrating the interface between the positive electrode 22, the negative electrode 24, and the separator 26 according to this embodiment. As shown in FIG. 16, the separator 26 according to this embodiment has a base layer 27 and a heat resistance layer (HRL) 28 provided on one surface of the base layer 27. An adhesive layer 6 is also present on the surface of the heat resistance layer 28.

[0080] As the substrate layer 27, any microporous film used in a separator of a conventionally known battery can be used without particular limitation. The substrate layer 27 is preferably a porous sheet-like member. The substrate layer 27 may have a single-layer structure or a two- or more-layer structure, for example, a three-layer structure. The substrate layer 27 is preferably made of a polyolefin resin. It is more preferable that the entire substrate layer 27 is made of a polyolefin resin. The substrate layer 27 may be, for example, a microporous film made of polyolefin, preferably a microporous film made of polyethylene. This ensures sufficient flexibility of the separator 26, and facilitates the production (winding and press molding) of the wound electrode body 20a. The polyolefin resin is preferably polyethylene (PE), polypropylene (PP), or a mixture thereof, and more preferably made of PE.

[0081] Although not particularly limited, the thickness of the base layer 27 (length in the stacking direction MD; the same applies below) is preferably 3 μm or more, and more preferably 5 μm or more. The thickness of the base layer 27 is preferably 25 μm or less, more preferably 18 μm or less, and even more preferably 14 μm or less. The air permeability of the base layer 27 is preferably 30 sec / 100cc to 500 sec / 100cc, more preferably 30 sec / 100cc to 300 sec / 100cc, and even more preferably 50 sec / 100cc to 200 sec / 100cc.

[0082] The heat-resistant layer 28 is provided on the substrate layer 27. The heat-resistant layer 28 is preferably formed on the substrate layer 27. The heat-resistant layer 28 may be provided directly on the surface of the substrate layer 27, or may be provided on the substrate layer 27 via another layer. The heat-resistant layer 28 is preferably formed on one or both sides of the substrate layer 27. However, the heat-resistant layer 28 is not essential and may be omitted in other embodiments. Here, the heat-resistant layer 28 is provided on the entire surface of the substrate layer 27 facing the positive electrode 22. This more effectively suppresses thermal shrinkage of the separator 26, contributing to improved safety of the battery 100. The basis weight of the heat-resistant layer 28 is uniform in the longitudinal direction LD and the winding axis direction WD of the separator 26. Although not particularly limited, the thickness of the heat-resistant layer 28 (length in the stacking direction MD; the same applies hereinafter) is preferably 0.3 μm or more, more preferably 0.5 μm or more, and even more preferably 1 μm or more. The thickness of the heat-resistant layer 28 is preferably 6 μm or less, and more preferably 4 μm or less. The heat-resistant layer 28 preferably contains an inorganic filler and a heat-resistant layer binder.

[0083] As the inorganic filler, any inorganic filler conventionally used for this type of application can be used without particular limitation. Preferably, the inorganic filler contains insulating ceramic particles. Among these, inorganic oxides such as alumina, zirconia, silica, and titania, metal hydroxides such as aluminum hydroxide, and clay minerals such as boehmite are preferred in consideration of heat resistance and availability, with alumina and boehmite being more preferred. Furthermore, from the viewpoint of suppressing thermal shrinkage of the separator 26, compounds containing aluminum are particularly preferred. The proportion of the inorganic filler relative to the total mass of the heat-resistant layer 28 is preferably 85% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more.

[0084] As the heat-resistant layer binder, any binder known in the art for this type of application can be used without any particular limitation. Specific examples include acrylic resins, fluorine-based resins (e.g., PVdF), epoxy resins, urethane resins, and ethylene vinyl acetate resins. Among these, acrylic resins are preferred.

[0085] Here, the adhesive layer 6 is provided on the surface facing the positive electrode 22 and abuts against the positive electrode 22. As shown in FIG. 16 , the adhesive layer 6 is preferably formed at least on the surface of the separator 26 facing the positive electrode 22. Here, the adhesive layer 6 is provided on the heat-resistant layer 28. The adhesive layer 6 is preferably formed on the heat-resistant layer 28. The adhesive layer 6 may be provided directly on the surface of the heat-resistant layer 28, or may be provided on the heat-resistant layer 28 via another layer. The adhesive layer 6 may be provided directly on the surface of the base layer 27, or may be provided on the base layer 27 via a layer other than the heat-resistant layer 28. The adhesive layer 6 has a relatively higher affinity with the electrolyte solution than, for example, the heat-resistant layer 28, and may be a layer that absorbs the electrolyte solution and swells. Although not particularly limited, the thickness of the adhesive layer 6 in the wound electrode body 20a (the length in the stacking direction MD in FIG. 16, which corresponds to T in FIG. 16; this can also be referred to as the thickness of the adhesive layer 6 after the pressing step) is preferably 0.1 μm or more, more preferably 0.2 μm or more, and even more preferably 0.5 μm or more. The thickness of the adhesive layer 6 is preferably 10 μm or less, preferably 5 μm or less, and more preferably 3 μm or less. That is, the thickness of the adhesive layer 6 in the wound electrode body 20a is preferably, for example, within the range of 0.1 μm to 10 μm. By keeping the thickness within this range, it is possible to suitably achieve the adhesiveness of the adhesive layer 6, uniformity in the charge / discharge reaction of the battery 100, and suppression of Li deposition.

[0086] The diameter of the adhesive layer 6 in the wound electrode body 20a (corresponding to D in FIG. 16; this can also be referred to as the diameter of the adhesive layer 6 after the pressing step) is, for example, 10 μm or more, preferably 50 μm or more, more preferably 75 μm or more, and even more preferably 100 μm or more. The thickness of the adhesive layer 6 is, for example, 600 μm or less, preferably 500 μm or less, preferably 300 μm or less, and more preferably 200 μm or less. That is, the thickness of the adhesive layer 6 in the wound electrode body 20a is preferably, for example, within the range of 50 μm to 500 μm. By keeping the thickness within this range, it is possible to suitably achieve the adhesiveness of the adhesive layer 6, uniformity of the charge / discharge reaction of the battery 100, and suppression of Li deposition.

[0087] For details about the resin that constitutes the adhesive layer 6, please refer to the corresponding section in <Battery Manufacturing Method>.

[0088] The electrolyte may be the same as conventional ones and is not particularly limited. The electrolyte is, for example, a non-aqueous electrolyte containing a non-aqueous solvent and a supporting salt. The non-aqueous solvent contains, for example, carbonates such as ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate. The supporting salt is, for example, a fluorine-containing lithium salt such as LiPF6. However, the electrolyte may be in a solid state (solid electrolyte) and integrated with the electrode assembly 20.

[0089] As shown in FIG. 10 , the positive electrode terminal 30 is inserted into a terminal insertion hole 18 formed at one end of the sealing plate 14 in the long side direction Y (the left end in FIG. 10 ). The positive electrode terminal 30 is preferably made of metal, more preferably aluminum or an aluminum alloy. Meanwhile, the negative electrode terminal 40 is inserted into a terminal insertion hole 19 formed at the other end of the sealing plate 14 in the long side direction Y (the right end in FIG. 10 ). The negative electrode terminal 40 is preferably made of metal, more preferably copper or a copper alloy. Here, these electrode terminals (positive electrode terminal 30, negative electrode terminal 40) each protrude from the same surface of the battery case 10 (specifically, the sealing plate 14). However, the positive electrode terminal 30 and the negative electrode terminal 40 may each protrude from different surfaces of the battery case 10. Furthermore, the electrode terminals (positive electrode terminal 30, negative electrode terminal 40) inserted into the terminal insertion holes 18, 19 are preferably fixed to the sealing plate 14 by crimping or the like.

[0090] As described above, as shown in FIG. 10 , the positive electrode terminal 30 is electrically connected to the positive electrodes 22 (see FIG. 13 ) of each of the wound electrode bodies 20a, 20b, and 20c inside the exterior housing 12 via the positive electrode current collecting portion 50 (positive electrode first current collecting portion 51, positive electrode second current collecting portion 52). The positive electrode terminal 30 is insulated from the sealing plate 14 by a positive electrode internal insulating member 70 and a gasket 90. The positive electrode internal insulating member 70 includes a base portion 70a interposed between the positive electrode first current collecting portion 51 and the sealing plate 14, and a protrusion portion 70b protruding from the base portion 70a toward the wound electrode body 20a. The positive electrode terminal 30 exposed to the outside of the battery case 10 through the terminal insertion hole 18 is connected to the positive electrode external conductive member 32 outside the sealing plate 14. On the other hand, as shown in FIG. 10 , the negative electrode terminal 40 is electrically connected to the negative electrode 24 (see FIG. 13 ) of each wound electrode body 20a via a negative electrode current collecting portion 60 (negative electrode first current collecting portion 61, negative electrode second current collecting portion 62) inside the exterior body 12. The negative electrode terminal 40 is insulated from the sealing plate 14 by a negative electrode internal insulating member 80 and a gasket 90. Like the positive electrode internal insulating member 70, the negative electrode internal insulating member 80 also has a base portion 80a interposed between the negative electrode first current collecting portion 61 and the sealing plate 14 and a protrusion portion 80b protruding from the base portion 80a toward the wound electrode body 20a. The negative electrode terminal 40 exposed to the outside of the battery case 10 through the terminal insertion hole 19 is connected to a negative electrode external conductive member 42 outside the sealing plate 14. An external insulating member 92 is interposed between the external conductive members (positive electrode external conductive member 32, negative electrode external conductive member 42) and the outer surface 14d of the sealing plate 14. The external insulating member 92 can insulate the external conductive members 32, 42 from the sealing plate 14.

[0091] Furthermore, the protrusions 70b, 80b of the internal insulating members (positive electrode internal insulating member 70, negative electrode internal insulating member 80) described above are disposed between the sealing plate 14 and the wound electrode body 20a. The protrusions 70b, 80b of the internal insulating members restrict upward movement of the wound electrode body 20a, preventing contact between the sealing plate 14 and the wound electrode body 20a.

[0092] <Battery uses> Battery 100 can be used for a variety of purposes, but is preferably used, for example, as a power source (driving power source) for motors mounted on vehicles such as passenger cars and trucks. The type of vehicle is not particularly limited, but examples include plug-in hybrid electric vehicles (PHEVs), hybrid electric vehicles (HEVs), and battery electric vehicles (BEVs). Battery 100 has reduced variation in battery reaction, and is therefore preferably used to construct a battery pack.

[0093] Although one embodiment of the present disclosure has been described above, the above embodiment is merely an example. The present disclosure can be implemented in various other forms. The present disclosure can be implemented based on the contents disclosed in this specification and the common general technical knowledge in the relevant field. The technology described in the claims includes various modifications and alterations of the above-exemplified embodiment. For example, it is possible to replace part of the above-described embodiment with other modified embodiments, and it is also possible to add other modified embodiments to the above-described embodiment. Furthermore, if a technical feature is not described as essential, it can be deleted as appropriate.

[0094] For example, in the above embodiment, the adhesive layer 6 is formed on the surface of the separator 26 facing the positive electrode 22, but this is not limiting. In other embodiments, the adhesive layer 6 may be formed on the surface of the separator 26 facing the negative electrode 22. Alternatively, the adhesive layer 6 may be formed on the surface of the separator 26 facing the positive electrode 22 and on the surface of the separator 26 facing the negative electrode 24. Furthermore, when the electrode body has two separators, an adhesive layer may be disposed on the surface of only one of the separators.

[0095] For example, in the above embodiment, the adhesive layer 6 has the first adhesive region 6A and the second adhesive region 6B, but is not limited to this. In other embodiments, the adhesive layer 6 may have other adhesive regions in addition to these regions.

[0096] For example, FIG. 17 is a view corresponding to FIG. 3 according to the third embodiment. FIG. 18 is a schematic longitudinal cross-sectional view taken along line XVIII-XVIII in FIG. 17. As shown in FIGS. 17 and 18, in the third embodiment, the separator 126 has a plurality of adhesive layers 106 arranged in a circular dot pattern in a plan view. The adhesive layers 106 have a second adhesive region 106B (peripheral region) and a first adhesive region 106A (central region). The thickness of the first adhesive region 106A (length in the MD direction in FIG. 18) is greater than the thickness of the second adhesive region 106B (length in the MD direction in FIG. 18). With this configuration, the separator 126 and the electrodes are weakly bonded together during the winding process, and only during the pressing process are the separator 126 and the electrodes strongly bonded together. The third embodiment may be similar to the first embodiment, except for the shape of the adhesive layer. The ratio between the thickness of the first adhesive region 106A and the thickness of the second adhesive region 106B can be determined by referring to the ratio between T1 and T2 described above.

[0097] For example, FIG. 19 is a view corresponding to FIG. 3 according to the fourth embodiment. FIG. 20 is a schematic longitudinal cross-sectional view taken along line XX-XX in FIG. 19. As shown in FIGS. 19 and 20, in the fourth embodiment, a separator 226 has a plurality of adhesive layers 206 arranged linearly in a plan view. The adhesive layers 206 have a first adhesive region 206A and a second adhesive region 206B. The thickness of the first adhesive region 206A (the length in the MD direction in FIG. 20) is greater than the thickness of the second adhesive region 206B (the length in the MD direction in FIG. 20). With this configuration, the separator 226 and the electrodes are weakly bonded together in the winding process, and only in the pressing process are the separator 226 and the electrodes strongly bonded together. The fourth embodiment may be similar to the first embodiment, except for the shape of the adhesive layer. The ratio between the thickness of the first adhesive region 206A and the thickness of the second adhesive region 206B can be determined by referring to the ratio of T1 to T2 described above.

[0098] For example, FIG. 21 is a view corresponding to FIG. 3 according to the fifth embodiment. FIG. 22 is a schematic longitudinal cross-sectional view taken along line XXII-XXII in FIG. 21. As shown in FIGS. 21 and 22, in the fifth embodiment, the separator 326 has multiple adhesive layers 306 arranged linearly in a plan view. The adhesive layers 306 each have a second adhesive region 306B and a first adhesive region 306A located on both sides of the second adhesive region 306B. With this configuration, the separator 326 and the electrodes are weakly bonded together during the winding process, and only during the pressing process are the separator 326 and the electrodes strongly bonded together. The fifth embodiment may be similar to the first embodiment, except for the shape of the adhesive layer. The ratio of the thickness of the first adhesive region 306A to the thickness of the second adhesive region 306B can be determined by referring to the ratio of T1 and T2 described above.

[0099] As described above, one aspect of the technology disclosed herein includes those described in the following items. Item 1: A manufacturing method for an electricity storage device including a flat wound electrode body in which a strip-shaped first electrode and a strip-shaped second electrode are wound with a strip-shaped separator interposed therebetween, the manufacturing method for an electricity storage device including: a winding step in which the first electrode and the second electrode are wound with the separator interposed therebetween to manufacture a wound body; and a pressing step in which, after the winding step, the wound body is press-molded to form a flat wound electrode body, wherein in the winding step, a separator having a partial adhesive layer on at least one surface is used, the adhesive layer includes a first adhesive region and a second adhesive region, and the thickness of the first adhesive region is greater than the thickness of the second adhesive region. Specific aspects of the technology disclosed herein include those described in the following items. Item 2: The method for producing an electricity storage device according to item 1, wherein the thickness T1 of the first adhesive region is 1.5 times or more the thickness T2 of the second adhesive region. Item 3: The method for manufacturing an electricity storage device according to Item 1, wherein the first adhesive region and the first electrode are adhered together in the winding step, and the second adhesive region and the first electrode are adhered together in the pressing step. Item 4: The method for producing an electricity storage device according to any one of Items 1 to 3, wherein the adhesive layer is arranged in a dot pattern in a plan view. Item 5: The method for producing an electricity storage device according to any one of Items 1 to 3, wherein the adhesive layer is arranged linearly in a plan view. Item 6: The method for producing an electricity storage device according to any one of Items 1 to 5, wherein, in a plan view, the ratio of the area on one side of the separator where the adhesive layer is formed to the area on one side of the separator is 0.005 to 0.5. Item 7: The method for producing an electricity storage device according to any one of items 1 to 6, wherein the ratio of the formation area of ​​the first adhesive region to the area of ​​the adhesive layer in plan view is 0.2 to 0.8. Item 8: The method for producing an electricity storage device according to any one of Items 1 to 7, wherein the main component of the resin constituting the first adhesive region is the same as the main component of the resin constituting the second adhesive region. Item 9: The method for producing an electricity storage device according to any one of items 1 to 8, further comprising, before the winding step, a forming step of forming the adhesive layer on at least one of the surfaces of the separator. Item 10: A separator for an electrical storage device having a partial adhesive layer on at least one surface, the adhesive layer including a first adhesive region and a second adhesive region, and a thickness T1 of the first adhesive region being 1.5 times or more the thickness T2 of the second adhesive region. Item 11: The separator for an electricity storage device according to Item 10, wherein the adhesive layers are arranged in a dot pattern in a plan view. Item 12: The separator for an electricity storage device according to Item 10, wherein the adhesive layers are arranged linearly in a plan view. Item 13: The separator for a power storage device according to any one of items 10 to 12, wherein in a plan view, the ratio of the area on one side of the separator where the adhesive layer is formed to the area on one side of the separator is 0.005 to 0.5. Item 14: The separator for an electricity storage device according to any one of items 10 to 13, wherein, in plan view, the ratio of the area where the first adhesive region is formed to the area of ​​the adhesive layer is 0.2 to 0.8. Item 15: The separator for an electricity storage device according to any one of Items 10 to 14, wherein a main component of the resin constituting the first adhesive region is the same as a main component of the resin constituting the second adhesive region. [Explanation of symbols]

[0100] 1 Electrode body manufacturing equipment 2. Laura 3 Winding core 4 Adhesive application section 5 Drying section 6 Adhesive layer 6A 1st adhesive area 6B 2nd adhesive area 10 Battery case 12 Exterior body 14 Sealing plate 15 Liquid injection hole 15a Sealing member 17 Gas exhaust valve 18,19 Terminal insertion holes 20 Electrode group 20a~20c electrode body 22 Positive electrode 23 Positive electrode tab group 24 Negative electrode 25 Negative electrode tab group 26 Separator 27 Base material layer 28 Heat-resistant layer 30 Positive terminal 32 Positive electrode external conductive member 40 Negative terminal 42 negative electrode external conductive member 50 Positive electrode current collector 60 Negative electrode current collector 70 Positive electrode internal insulating material 80 Negative electrode internal insulating member 90 Gasket 92 External insulating member 100 batteries 200 press machines

Claims

1. A method for manufacturing an electricity storage device including a flat wound electrode body in which a strip-shaped first electrode and a strip-shaped second electrode are wound with a strip-shaped separator interposed therebetween, a winding step of winding the first electrode and the second electrode with the separator interposed therebetween to produce a wound body; a pressing step of press-molding the wound body to form a flat wound electrode body after the winding step; It encompasses In the winding step, a separator having a plurality of adhesive layers arranged in a dot pattern in a plan view on at least one surface is used, the adhesive layer includes a first adhesive region and a second adhesive region; The thickness T1 of the first adhesive region is 1.5 times or more the thickness T2 of the second adhesive region, the first adhesive region is one of an outer peripheral region and a central region of the dot-shaped adhesive layer, The method for manufacturing an electricity storage device, wherein the second adhesive region is the other of the peripheral region and the central region of the dot-shaped adhesive layer.

2. A method for manufacturing an electricity storage device including a flat wound electrode body in which a strip-shaped first electrode and a strip-shaped second electrode are wound with a strip-shaped separator interposed therebetween, a winding step of winding the first electrode and the second electrode with the separator interposed therebetween to produce a wound body; a pressing step of press-molding the wound body to form a flat wound electrode body after the winding step; It encompasses In the winding step, a separator having a plurality of adhesive layers each arranged linearly in a plan view on at least one surface is used, the adhesive layer includes a first adhesive region and a second adhesive region; The thickness T1 of the first adhesive region is 1.5 times or more the thickness T2 of the second adhesive region, A method for manufacturing an electricity storage device, wherein the first adhesive region and the second adhesive region are arranged within one adhesive layer so that the first adhesive region and the second adhesive region each extend linearly.

3. In the winding step, the first adhesive region and the first electrode are adhered to each other, The method for manufacturing an electricity storage device according to claim 1 , wherein the second adhesive region and the first electrode are adhered to each other in the pressing step.

4. 3. The method for producing an electricity storage device according to claim 1, wherein a ratio of an area on one side of the separator where the adhesive layer is formed to an area on one side of the separator in a plan view is 0.005 to 0.

5.

5. 3. The method for manufacturing an electricity storage device according to claim 1, wherein a ratio of a formation area of ​​the first adhesive region to an area of ​​the adhesive layer in a plan view is 0.2 to 0.

8.

6. The method for manufacturing an electricity storage device according to claim 1 , wherein a main component of the resin constituting the first adhesive region is the same as a main component of the resin constituting the second adhesive region.

7. The method for manufacturing an electricity storage device according to claim 1 , further comprising, before the winding step, a forming step of forming the adhesive layer on at least one surface of the separator.

Images