Electricity storage device and method for manufacturing the same

Abstract

To provide a technology that can obtain a power storage device including a wound electrode body with high productivity.SOLUTION: In an aspect of a power storage device (hereinafter referred to as a battery) disclosed herein, a separator 26 has a first adhesive layer 1A and a second adhesive layer 1B on at least one surface of the separator. In plan view of the separator 26, the first adhesive layer 1A is partially formed, and the second adhesive layer 1B is partially formed. The first adhesive layer 1A is composed of an adhesive layer that has adhesiveness to a positive electrode 22 by coming into contact with the positive electrode 22 facing the first adhesive layer 1A at ordinary temperature. The second adhesive layer 1B is composed of an adhesive layer that has no adhesiveness to the positive electrode 22 when the first adhesive layer 1A adheres to the facing positive electrode 22, and thereafter has adhesiveness to the positive electrode 22 when some physical means is applied.SELECTED DRAWING: Figure 16

Description

[Technical Field]

[0001] The present disclosure relates to an electricity storage device and a method for manufacturing the electricity storage device. [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 together during winding of the components, 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 or wrinkles in the separator. On the other hand, if the separator does not have such an adhesive resin, there is a risk of miswinding occurring in the wound body, which 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 electricity storage devices (e.g., batteries) including wound electrode bodies having the adhesive layer described above, and in the manufacture of such electricity storage devices.

[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 object, the present disclosure provides 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. The method for manufacturing an electricity storage device 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, wherein the winding step uses the separator having a first adhesive layer and a second adhesive layer on at least one of its surfaces, the first adhesive layer is partially formed and the second adhesive layer is partially formed in a plan view of the separator, a main component of the resin constituting the first adhesive layer is different from a main component of the resin constituting the second adhesive layer, and the adhesiveness of the second adhesive layer to the first electrode is weaker than the adhesiveness of the first adhesive layer to the first electrode under temperature conditions in the winding 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.

[0007] From another aspect, the present disclosure provides an electricity 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 separator having a first adhesive layer and a second adhesive layer on at least one of its surfaces, the first adhesive layer being partially formed and the second adhesive layer being partially formed in a plan view of the separator, the first adhesive layer being composed of an adhesive layer that has adhesiveness to the first electrode upon contact with the first electrode facing the first adhesive layer at room temperature, and the second adhesive layer being composed of an adhesive layer that does not have adhesiveness to the first electrode when the first adhesive layer and the facing first electrode are bonded together, but that has adhesiveness to the first electrode when some physical means is subsequently applied. Such an electricity storage device is manufactured by the above-described method for manufacturing an electricity storage device, and can therefore be said to be an electricity storage device obtained with high productivity. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a flowchart illustrating a method for manufacturing a battery according to an embodiment. [Figure 2] FIG. 10 is a schematic diagram for explaining a winding step according to one embodiment. [Figure 3] FIG. 2 is a schematic diagram illustrating a wound body before a pressing process according to one embodiment. [Figure 4] FIG. 10 is a schematic diagram showing a wound body after a pressing process according to an embodiment. [Figure 5] FIG. 2 is a schematic diagram illustrating the configuration of a separator according to one 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 collector and a negative electrode second current collector 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. 6 is a view corresponding to FIG. 5 according to the second embodiment. [Figure 18] FIG. 10 is a view corresponding to FIG. 5 according to the third embodiment. [Figure 19] FIG. 10 is a view corresponding to FIG. 5 according to the fourth embodiment. [Figure 20] FIG. 10 is a view corresponding to FIG. 5 according to the fifth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] 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."

[0010] 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 (e.g., 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.

[0011] <Battery manufacturing method> 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, for example, the first electrode is a negative electrode 24 and the second electrode is a positive electrode 22. Note that the following description will focus on the wound electrode body 20a, but the same applies to the wound electrode bodies 20b and 20c.

[0012] FIG. 1 is a flowchart for explaining a manufacturing method of a battery 100 according to this embodiment (i.e., a battery 100 including flat wound electrode bodies 20a, 20b, and 20c in which a strip-shaped positive electrode 22 and a strip-shaped negative electrode 24 are wound with a strip-shaped separator 26 interposed therebetween). FIG. 5 is a schematic diagram showing the configuration of a separator according to this embodiment. As shown in FIG. 1, the manufacturing method of a battery according to this embodiment includes a winding step (step S1) in which the positive electrode 22 and the negative electrode 24 are wound with a separator 26 interposed therebetween to manufacture a wound body 20A; and a pressing step (step S2) in which, after the winding step, the wound body 20A is press-molded to form a flat wound electrode body 20a. In the winding step, a separator 26 is used that has a first adhesive layer 1A and a second adhesive layer 1B on at least one of its surfaces. Furthermore, as shown in FIG. 5, in a plan view of the separator 26, the first adhesive layer 1A is partially formed and the second adhesive layer 1B is partially formed. The main component of the resin constituting the first adhesive layer 1A is different from the main component of the resin constituting the second adhesive layer 1B. Here, the main component can mean a component that is contained in an amount of, for example, 50% by volume or more, 60% by volume or more, 70% by volume or more, 80% by volume or more, 90% by volume or more, or 95% by volume or more (or even 100% by volume) when the entire resin constituting the first adhesive layer 1A (second adhesive layer 1B) is taken as 100% by volume. Under the temperature conditions in the winding step, the adhesiveness of the second adhesive layer 1B to the positive electrode 22 is weaker than the adhesiveness of the first adhesive layer 1A to the positive electrode 22.

[0013] According to the manufacturing method of the battery 100 described above, the positive electrode 22 and the separator 26 are not strongly bonded to each other in the winding step, but are strongly bonded to each other in the pressing step. Therefore, when the positional relationship between the positive electrode 22 and the separator 26 changes in the pressing step, the positional relationship changes appropriately. This can suitably prevent wrinkles and the like from occurring in the separator 26. Furthermore, because the separator 26 has adhesive layers (first adhesive layer 1A and second adhesive layer 1B), it can suitably prevent misalignment of the wound body 20A (more specifically, misalignment between the separator 26 and the positive electrode 22 within the wound body 20A, which will be described later. This is particularly likely to occur when the wound body 20A is removed from the winding core B, or misalignment during transport to the pressing step, which will be described later). 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. Each step will be described below.

[0014] (Step S1: Winding process) As described above, in this step, the positive electrode 22 and the negative electrode 24 are wound with the separator 26 interposed therebetween to produce a wound body 20A. Here, FIG. 2 is a schematic diagram for explaining the winding step according to this embodiment. FIG. 5 is a schematic diagram showing the configuration of a separator according to this embodiment. FIG. 6 is a schematic diagram showing the state of the separator before the winding step according to this embodiment. Note that, for ease of explanation, FIG. 6 shows only one separator 26 and positive electrode 22, but the same effect can be obtained with the other separator 26 and positive electrode 22. The same applies to FIGS. 7 and 8 described below. First, a strip-shaped separator 26, a strip-shaped positive electrode 22, and a strip-shaped negative electrode 24 are prepared. Here, as shown in FIG. 5, in this embodiment, a separator 26 having a first adhesive layer 1A and a second adhesive layer 1B on one surface is used as the separator. The separator may be a commercially available separator in which the first adhesive layer 1A and the second adhesive layer 1B are formed on the surface of the separator 26 in advance, or one in which the first adhesive layer 1A and the second adhesive layer 1B are formed on the surface of the separator 26 by gravure printing, inkjet printing, or the like. In the latter case, it is preferable to include a coating step, prior to the winding step, of applying an adhesive layer (here, the first adhesive layer 1A and the second adhesive layer 1B) to at least one surface of the separator 26 using a coating device. It is also preferable that this coating step be performed immediately before the winding step, for example, from the viewpoint of suitably preventing foreign matter from being adsorbed onto the formed adhesive layer.

[0015] As described above, with regard to the first adhesive layer 1A and the second adhesive layer 1B, under the temperature conditions in the winding step, the adhesiveness (adhesive strength) of the second adhesive layer 1B to the positive electrode 22 is smaller than the adhesiveness (adhesive strength) of the first adhesive layer 1A to the positive electrode 22. Here, the temperature in the winding step is preferably 50°C or lower, more preferably 40°C or lower, and even more preferably 35°C or lower. The winding step is preferably performed at 10°C or higher. Under these temperature conditions, by making the adhesiveness (adhesive strength) of the second adhesive layer 1B to the positive electrode 22 smaller than the adhesiveness (adhesive strength) of the first adhesive layer 1A to the positive electrode 22, it is possible to suitably prevent the separator 26 and the positive electrode 22 from being strongly bonded together in the winding step, and therefore it is possible to appropriately change the positional relationship between the positive electrode 22 and the separator 26 in the pressing step described below.

[0016] The adhesiveness (adhesion strength) of the first adhesive layer 1A (second adhesive layer 1B) to the first electrode (here, the positive electrode 22) under the temperature conditions of the winding step can be a value measured as follows. Specifically, it can be the peel strength obtained when a 90° peel test is conducted between the separator 26 having the first adhesive layer 1A (the separator 26 having the second adhesive layer 1B) and the first electrode (here, the positive electrode 22) when the temperature and pressure (for example, about 0.01 MPa to 0.1 MPa) in the winding step is applied. Although not particularly limited, the adhesive strength (peel strength) of the first adhesive layer 1A to the first electrode (here, the positive electrode 22) 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). The adhesive strength (peel strength) of the second adhesive layer 1B 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 above-mentioned winding step, the difference between the adhesive strength (peel strength) of the first adhesive layer 1A to the first electrode (here, the positive electrode 22) and the adhesive strength (peel strength) of the second adhesive layer 1B to the first electrode (here, the positive electrode 22) 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). Such a peel test can be measured, for example, by the following method. First, the separator 26 and the first electrode (here, the positive electrode 22) having the first adhesive layer 1A (second adhesive layer 1B) are each cut to a size of 2.0 cm long and 7.0 cm wide, and the cut separator 26 and positive electrode 22 are stacked. Next, the separator 26 and the positive electrode 22 are bent so that they form a 90° angle. Then, using a tensile tester or the like, one side of the separator 26 opened at 90° and one side of the positive electrode 22 are gripped and pulled at a pulling rate of 50 mm / min, and the strength when the two are peeled is measured. In this way, the peel strength can be measured. The peel strength of the second adhesive layer 1B before and after the above pressing process, which will be described later, can also be measured in a similar manner using the separator 26 and the positive electrode 22 having the second adhesive layer 1B.

[0017] As described above, the main component of the resin constituting the first adhesive layer 1A is different from the main component of the resin constituting the second adhesive layer 1B. The first adhesive layer 1A and the second adhesive layer 1B also contain an adhesive binder. Examples of adhesive binders include acrylic resins, fluorine-based resins, rubber resins, urethane resins, silicone resins, epoxy resins, and combinations thereof. An example of a rubber resin is styrene butadiene rubber (SBR). Fluorine-based resins and acrylic resins are preferred because they have high flexibility and can more effectively exhibit adhesion to the first electrode (here, the positive electrode 22). Examples of fluorine-based resins include polyvinylidene fluoride (PVdF) and polytetrafluoroethylene (PTFE). The type of adhesive binder may be the same as or different from the heat-resistant layer binder. The first adhesive layer 1A and the second adhesive layer 1B are preferably composed mainly of an adhesive binder. When the entire first adhesive layer 1A (second adhesive layer 1B) is taken as 100% by volume, the proportion of the adhesive binder is, for example, 50% by volume or more, 60% by volume or more, preferably 70% by volume or more, more preferably 80% by volume or more, and even more preferably 90% by volume or more. This ensures that the desired adhesiveness to the positive electrode 22 is adequately exhibited, and also makes the separator 26 more easily deformable during press molding.

[0018] Here, under the temperature conditions in the winding step, the adhesiveness of the second adhesive layer 1B to the positive electrode 22 is preferably lower than that of the first adhesive layer 1A. Therefore, the glass transition point of the resin constituting the first adhesive layer 1A is preferably lower than that of the resin constituting the second adhesive layer 1B. While not limited thereto, the glass transition point of the resin constituting the first adhesive layer 1A is, for example, 0°C or lower, preferably -10°C or lower. The glass transition point of the resin constituting the first adhesive layer 1A may also be, for example, -20°C or higher. Meanwhile, the glass transition point of the resin constituting the second adhesive layer 1B is, for example, room temperature or higher, preferably 30°C or higher, more preferably 40°C or higher, or 50°C or higher. The glass transition point of the resin constituting the second adhesive layer 1B may also be, for example, 60°C or lower. The glass transition point can be measured, for example, according to the method specified in JIS K 7121. Examples of resins constituting the first adhesive layer 1A include PVdF, SBR, acrylic resins, etc., which have a low glass transition point as described above. Furthermore, resins constituting the second adhesive layer 1B preferably have a glass transition point above room temperature. Examples of such resins include PVdF, acrylic resins, epoxy resins, etc., which have a high glass transition point as described above. Furthermore, from the viewpoint of ease of handling, the first adhesive layer 1A and the second adhesive layer 1B preferably have adhesiveness at room temperature (e.g., about 25°C). Here, adhesiveness (adhesion) can mean, for example, that the peel strength in a 90° peel test according to 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).

[0019] The first adhesive layer 1A and the second adhesive layer 1B may contain other materials (for example, inorganic fillers such as alumina, titania, boehmite, etc.) in addition to the adhesive binder. When the first adhesive layer 1A and the second adhesive layer 1B contain an inorganic filler, the proportion of the inorganic filler relative to the total mass of the first adhesive layer 1A (second adhesive layer 1B) is preferably 80 mass% or less, more preferably 50 mass% or less, and even more preferably 30 mass% or less.

[0020] In a preferred embodiment, the first adhesive layer 1A is composed of an adhesive layer that, at room temperature (e.g., about 25°C), becomes adhesive to the positive electrode 22 upon contact with the positive electrode 22 facing the first adhesive layer 1A. The second adhesive layer 1B is composed of an adhesive layer that does not have adhesive to the positive electrode 22 when the first adhesive layer 1A and the positive electrode 22 facing it are bonded together, but that becomes adhesive to the positive electrode 22 when some physical means is subsequently applied. Examples of such physical means include heating, pressurization, energy irradiation such as light, and combinations of these. The pressure in such pressurization may be, for example, 0.1 MPa or more, preferably 1 MPa or more, and may be, for example, 5 MPa or less. The temperature in such heating may be, for example, 50°C or more, preferably 70°C or more, and may be, for example, 80°C or less. The energy in such energy irradiation may be, for example, 1 J / sec to 20 J / sec. The second adhesive layer 1B does not have adhesive properties when it comes into contact with the first electrode (here, the positive electrode 22) at room temperature, for example, but can be said to be an adhesive layer configured to bond the separator 26 and the first electrode (here, the positive electrode 22) by applying heat, warming, light, or other energy as described above. On the other hand, the first adhesive layer 1A can be said to be an adhesive layer configured to bond the separator 26 and the first electrode (here, the positive electrode 22) by coming into contact with the first electrode (here, the positive electrode 22) at room temperature (for example, contact with a pressing force of about 0.01 MPa to 0.1 MPa). Although not particularly limited, the 90° peel strength between first adhesive layer 1A and positive electrode 22 at room temperature when first adhesive layer 1A comes into contact with the opposing first electrode (here, positive electrode 22) 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 90° peel strength between second adhesive layer 1B and the first electrode (here, positive electrode 22) when some physical means is applied 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).Examples of resins constituting the first adhesive layer 1A include PVdF, SBR, and acrylic resins, and examples of resins constituting the second adhesive layer 1B include acrylic resins and epoxy resins.

[0021] In a preferred embodiment, the first adhesive layer 1A has adhesiveness under the temperature conditions in the winding step. This configuration is preferable because it allows the separator 26 and the positive electrode 22 to be easily bonded together in the winding step. In addition, the second adhesive layer 1B can also be made adhesive under the temperature conditions in the winding step.

[0022] In a preferred embodiment, in the winding step, the first adhesive layer 1A and the first electrode (here, the positive electrode 22) are bonded together, and the second adhesive layer 1B and the first electrode (here, the positive electrode 22) are bonded together with a force weaker than the adhesive force between the first adhesive layer 1A and the first electrode (here, the positive electrode 22), or the second adhesive layer 1B and the first electrode (here, the positive electrode 22) are not bonded together. Then, in the pressing step, the second adhesive layer 1B and the first electrode (here, the positive electrode 22) are bonded together more strongly than before the pressing step. Note that, although not particularly limited, the difference in peel strength of the second adhesive layer 1B 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).

[0023] Next, as shown in FIG. 2, the prepared separator 26, positive electrode 22, and negative electrode 24 are transported to a winding core B using a transport roller A and wound around the winding core B to produce a wound body 20A. Here, a cylindrical winding core B is used, but this is not limiting; for example, a flat winding core may also be used. The cross-sectional shape of the wound body 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). Note that the number of windings is preferably adjusted appropriately taking into account the performance and manufacturing efficiency of the target battery 100. In some embodiments, the number of windings may be 20 or more, or 30 or more.

[0024] As shown in FIG. 5 , in this embodiment, the first adhesive layer 1A is formed into a predetermined pattern (a predetermined shape), and the second adhesive layer 1B is formed into a predetermined pattern (a predetermined shape). In this embodiment, the first adhesive layer 1A is partially formed, and the second adhesive layer 1B is partially formed. This configuration is preferable because it allows the effects of the technology disclosed herein to be obtained more easily (effectively). Also, as shown in FIG. 5 , in this embodiment, the pattern is in the form of dots (here, dots that are circular in a plan view of the separator 26). In this embodiment, the first adhesive layer 1A and the second adhesive layer 1B are alternately arranged in the short-side direction Y of the separator 26. Note that, in this embodiment, the number of dots is six in the Y direction of the separator 26, but is not limited thereto, and the number of dots is preferably changed as appropriate depending on the composition of the first adhesive layer 1A and the second adhesive layer 1B, etc. In other embodiments, the pattern may be a dot shape having a shape other than a circle when viewed from above (for example, an ellipse or a polygon when viewed from above), or may be a stripe shape, a track shape, or the like. The pattern may be one of the shapes described above, or a combination of two or more of them. Examples of other patterns include the patterns of the second to fifth embodiments described below. In other embodiments, the first adhesive layer 1A and the second adhesive layer 1B may be alternately arranged in the long side direction Z of the separator 26.

[0025] 5 and 6, in this embodiment, the first adhesive layer 1A and the second adhesive layer 1B are each formed in the shape of a circular dot in a plan view of the separator 26, and the diameter (specifically, diameter) D1 of the dot in the first adhesive layer 1A is smaller than the diameter (specifically, diameter) D2 of the dot in the second adhesive layer 1B. With this configuration, after the pressing step described below, the variation in the volume of each dot between the first adhesive layer 1A and the second adhesive layer 1B is reduced, thereby suitably suppressing non-uniformity in the reaction of the battery 100. While not particularly limited, the value of the ratio (D1 / D2) of D1 to D2 is, for example, 0.1 or more, and from the viewpoint of more suitably obtaining the above-described effects, is preferably 0.3 or more, and more preferably 0.5 or more. The upper limit of the value of the ratio (D1 / D2) is, for example, 0.8 or less, and may be 0.6 or less. Although not particularly limited, the sizes of the dot diameters D1 and D2 are, for example, 50 μm or more, more preferably 75 μm or more, and even more preferably 100 μm or more. The upper limits of the dot diameters D1 and D2 are, for example, 500 μm or less, more preferably 300 μm or less, and even more preferably 200 μm or less. That is, the sizes of the dot diameters D1 and D2 are preferably within the range of, for example, 50 μm to 500 μm. In other embodiments, the dot diameters D1 and D2 may be the same, or the dot diameter D1 may be larger than the dot diameter D2.

[0026] As shown in FIG. 6, in this embodiment, the thickness T1 of the first adhesive layer 1A (more specifically, the thickness in the MD direction in FIG. 6) and the thickness T2 of the second adhesive layer 1B (more specifically, the thickness in the MD direction in FIG. 6) are substantially the same. However, in other embodiments, the thickness T1 of the first adhesive layer 1A may be greater than the thickness T2 of the second adhesive layer 1B. Although not particularly limited, in such cases, the value of the ratio (T1 / T2) of T1 to T2 is, for example, 1.2 or more, and from the viewpoint of more suitably obtaining the effects described above, it is preferably 1.5 or more (e.g., greater than 1.5), and more preferably 2 or more (e.g., greater than 2). Furthermore, the upper limit of the value of the ratio (T1 / T2) is, for example, 3 or less, and may be 2.5 or less. Furthermore, although not particularly limited, the magnitudes of T1 and T2 are 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 the size of T1 and T2 is preferably 10 μm or less, more preferably 5 μm or less, and even more preferably 3 μm or less. Setting T1 and T2 within the above-mentioned ranges is preferable from the viewpoints of adhesion, uniformity of the charge / discharge reaction of the battery 100, suppression of Li deposition, etc. The size of T1 and T2 is preferably within the range of 0.1 μm to 10 μm, for example.

[0027] Although not particularly limited, the value of the ratio (Q / P) of the total formation area Q of the first adhesive layer 1A on one side of the separator 26 to the area P of one side of the separator 26 is, for example, 0.005 or more, and from the viewpoint of suitably ensuring adhesion between the separator 26 and the positive electrode 22, it is preferably 0.01 or more, more preferably 0.03 or more, and may be, for example, 0.05 or more. Furthermore, the upper limit of the value of the ratio (Q / P) is, for example, 0.5 or less, and from the viewpoint of obtaining a battery 100 with suitably reduced resistance (in other words, a battery 100 with suitably suppressed deterioration in output characteristics), it is preferably 0.3 or less, more preferably 0.2 or less, and even more preferably 0.1 or less. The value of the ratio (Q / P) is preferably, for example, within the range of 0.01 to 0.3. Furthermore, although not particularly limited, the value of the ratio (R / P) of the total formation area R of the second adhesive layer 1B on one side of the separator 26 to the area P of one side of the separator 26 is, for example, 0.005 or more, and from the viewpoint of suitably ensuring the adhesion between the separator 26 and the positive electrode 22, it is preferably 0.01 or more, more preferably 0.03 or more, and may be, for example, 0.05 or more. Furthermore, the upper limit of the value of the ratio (R / P) is, for example, 0.5 or less, and from the viewpoint of obtaining a battery 100 with suitably reduced resistance (in other words, a battery 100 with suitably suppressed deterioration in output characteristics), it is preferably 0.3 or less, more preferably 0.2 or less, and even more preferably 0.1 or less. The value of the ratio (R / P) is preferably, for example, within the range of 0.01 to 0.3. The total formation area of ​​the first adhesive layers 1A (second adhesive layers 1B) means the area of ​​all of the first adhesive layers 1A (second adhesive layers 1B) in a plan view of the separator 26.

[0028] As shown in FIG. 6 , in this embodiment, the total area Q of the first adhesive layer 1A is smaller than the total area R of the second adhesive layer 1B. This configuration results in weak adhesion between the first adhesive layer 1A, the second adhesive layer 1B, and the positive electrode 22 during the winding process, and strong adhesion between the first adhesive layer 1A, the second adhesive layer 1B, and the positive electrode 22 during the pressing process. This is preferable from the viewpoint of achieving the effects of the technology disclosed herein. Furthermore, this configuration can effectively achieve uniformity in the charge / discharge reactions of the battery 100. While not particularly limited, the value of the ratio (Q / R) of Q to R is, for example, 0.1 or more. From the viewpoint of more effectively achieving the effects described above, it is preferably 0.2 or more, and more preferably 0.3 or more. The upper limit of the value of the ratio (Q / R) is, for example, 0.7 or less, and may be 0.5 or less. In other embodiments, the total formation area Q of the first adhesive layer 1A and the total formation area R of the second adhesive layer 1B may be the same, or the total formation area Q of the first adhesive layer 1A may be smaller than the total formation area R of the second adhesive layer 1B.

[0029] Although not particularly limited, the basis weight of the first adhesive layer 1A 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 first adhesive layer 1A is, for example, 2.0 g / m 2 and preferably 1.0 g / m 2 or less, more preferably 0.05 g / m 2 Although not particularly limited, the basis weight of the second adhesive layer 1B on one surface 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 second adhesive layer 1B is, for example, 2.0 g / m 2 and preferably 1.0 g / m 2 or less, more preferably 0.05 g / m 2The "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).

[0030] (Step S2: Pressing process) As described above, in this step, the wound body 20A obtained in the winding step is press-molded to form a flat wound electrode body 20a. Here, FIG. 3 is a schematic diagram showing the wound body 20A before pressing according to this embodiment. FIG. 4 is a schematic diagram showing the wound body 20A after pressing according to this embodiment. First, as shown in FIG. 3, the wound body 20A is placed in a press C having a pair of opposing pressing surfaces, and then pressed in the direction of the outline arrow to obtain a flat wound electrode body 20a. Here, the pressing pressure can be, for example, in the range of 0.1 MPa to 20 MPa (preferably, 5 MPa to 10 MPa). Furthermore, this pressing can be unheated pressing or heated pressing. In the case of heated pressing, the heating temperature can be, for example, in the range of 50°C to 100°C (preferably, 70°C to 90°C). The electrode body 20a in a flat shape after press molding has a pair of curved portions 20r with curved outer surfaces and a flat portion 20f with a flat outer surface connecting the pair of curved portions 20r. Although not shown, a positive electrode tab group 23 with stacked positive electrode tabs 22t 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 with stacked negative electrode tabs 24t 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 in the width direction Y of the wound electrode body. Furthermore, the surface layer of the separator 26 can be bonded to the positive electrode 22 (negative electrode 24) by press molding.

[0031] Here, Fig. 8 is a schematic diagram showing the state of the separator 26 after the pressing process according to this embodiment. As shown in Fig. 8, in the pressing process, the second adhesive layer 1B and the positive electrode 22 are more strongly bonded together than in the state before the pressing. In this way, in the pressing process, the separator 26 and the positive electrode 22 are bonded together by the second adhesive layer 1B, and therefore, an increase in the thickness of the wound electrode body 20a after pressing can be suitably suppressed. In other words, the ease of inserting the wound electrode body 20a into the battery case 10 can be suitably improved.

[0032] Furthermore, it is preferable that the thickness t1 of the first adhesive layer 1A and the thickness t2 of the second adhesive layer 1B after the pressing process are substantially the same. It is also preferable that the dot diameter d1 of the first adhesive layer 1A and the dot diameter d2 of the second adhesive layer 1B after the pressing process are substantially the same. It is also preferable that the volume of the first adhesive layer 1A and the volume of the second adhesive layer 1B after the pressing process are substantially the same. With this configuration, the resistance of the battery 100 can be suitably reduced.

[0033] Although not shown, in this embodiment, a separator 26 is disposed on the outermost surface of the press-molded wound electrode body 20a, and a stop tape is attached to the end of the winding of the separator 26 to maintain the shape of the wound electrode body 20a. Any conventionally known 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 body 20a. In this manner, the electrode bodies 20a, 20b, and 20c according to this embodiment can be fabricated.

[0034] Next, an electrode assembly 20 integrated with the sealing plate 14 is produced. Specifically, first, as shown in Fig. 14, 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).

[0035] 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.

[0036] 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).

[0037] 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.

[0038] <Battery configuration> Next, the battery 100 obtained by the above-described battery manufacturing method will be described.

[0039] 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.

[0040] As shown in Fig. 10, the battery 100 includes a battery 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 collecting portion 50, a negative electrode current collecting portion 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 also includes an electrolyte. Here, the battery 100 is a lithium-ion secondary battery.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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. 10 , 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.

[0045] FIG. 13 is a perspective view schematically illustrating an electrode assembly 20 attached to a sealing plate 14. In this embodiment, a plurality of (here, three) wound electrode assemblies 20a, 20b, and 20c are housed inside the battery case 10. The number of wound electrode assemblies 20 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 each electrode assembly 20 in the long side direction Y (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 assemblies 20a, 20b, and 20c are connected in parallel. However, the wound electrode assemblies 20a, 20b, and 20c may also be connected in series. The wound electrode assembly 20 is housed inside the exterior body 12 of the battery case 10 while being covered with an electrode assembly holder 29 (see FIG. 11) made of a resin sheet.

[0046] 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 first adhesive layer 1A and the second adhesive layer 1B that are formed on the surface of the separator 26 are 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.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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).

[0053] 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 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.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] 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).

[0058] Next, the separator 26, first adhesive layer 1A, and second adhesive layer 1B that characterize the battery 100 (i.e., the battery 100 including the flat wound electrode bodies 20a, 20b, 20c in which a strip-shaped positive electrode 22 and a strip-shaped negative electrode 24 are wound with a strip-shaped separator 26 interposed therebetween) will be described. As shown in FIG. 5, the separator 26 according to this embodiment has the first adhesive layer 1A and the second adhesive layer 1B on one surface. In addition, in a plan view of the separator 26, the first adhesive layer 1A is partially formed, and the second adhesive layer 1B is partially formed. The first adhesive layer 1A is composed of an adhesive layer that, at room temperature (e.g., about 25°C), adheres to the positive electrode 22 upon contact with the positive electrode 22 facing the first adhesive layer 1A. The second adhesive layer 1B is composed of an adhesive layer that does not adhere to the positive electrode 22 when the first adhesive layer 1A and the positive electrode 22 facing it are bonded together, but that subsequently adheres to the positive electrode 22 when some physical means is applied. Because the battery 100 is manufactured by the manufacturing method for the battery 100 described above, it can be said to be a battery including the wound electrode bodies 20a, 20b, 20c obtained with high productivity (in other words, with suitably reduced costs). The separator 26, the first adhesive layer 1A, and the second adhesive layer 1B will be described below.

[0059] As shown in FIGS. 15 and 5, 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.

[0060] Here, two separators 26 are used for one wound electrode body 20a. As in this embodiment, it is preferable that one wound electrode body 20a includes two separators 26, i.e., a first separator and a second separator. Here, the two separators have the same configuration, but they may also be different.

[0061] 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. In addition, a first adhesive layer 1A and a second adhesive layer 1B are present on the surface of the heat resistance layer 28.

[0062] 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. The substrate layer 27 is more preferably made entirely of a polyolefin resin. The substrate layer 27 is preferably a microporous film made of, for example, 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.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] As the heat-resistant layer binder, any binder that has been conventionally used 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.

[0067] The first adhesive layer 1A and the second adhesive layer 1B are provided on the surface facing the positive electrode 22 and abut against the positive electrode 22. As shown in FIG. 16, the first adhesive layer 1A and the second adhesive layer 1B are preferably formed on at least the surface of the separator 26 facing the positive electrode 22. Here, the first adhesive layer 1A and the second adhesive layer 1B are provided on the heat-resistant layer 28. The first adhesive layer 1A and the second adhesive layer 1B are preferably formed on the heat-resistant layer 28. The first adhesive layer 1A and the second adhesive layer 1B 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 first adhesive layer 1A and the second adhesive layer 1B 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 first adhesive layer 1A and the second adhesive layer 1B may have a relatively higher affinity for the electrolyte solution than, for example, the heat-resistant layer 28, and may be layers that absorb the electrolyte solution and swell. Although not particularly limited, the thickness of the first adhesive layer 1A and the second adhesive layer 1B in the wound electrode body 20a (the length in the stacking direction MD in FIG. 16, which corresponds to t1 and t2 in FIG. 8, respectively; the same applies below) 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 first adhesive layer 1A and the second adhesive layer 1B is preferably 10 μm or less, preferably 5 μm or less, and more preferably 3 μm or less. That is, the thickness of the first adhesive layer 1A and the second adhesive layer 1B in the wound electrode body 20a is preferably, for example, in the range of 0.1 μm to 10 μm. By keeping the thickness within this range, it is possible to preferably achieve the adhesion of the first adhesive layer 1A and the second adhesive layer 1B, uniformity of the charge / discharge reaction of the battery 100, and suppression of Li deposition, etc.

[0068] For details on the partial formation (pattern formation) of the first adhesive layer 1A and the second adhesive layer 1B on the separator 26, please refer to the corresponding section in <Battery manufacturing method>.

[0069] For details about the types of resins constituting the first adhesive layer 1A and the second adhesive layer 1B, please refer to the corresponding section in <Battery manufacturing method>.

[0070] In a preferred embodiment, the ratio (Q / P) of the total area Q of the first adhesive layer 1A on one side of the separator 26 to the area P of one side of the separator 26 is 0.01 to 0.3. Also, the ratio (R / P) of the total area R of the second adhesive layer 1B on one side of the separator 26 to the area P of one side of the separator 26 is 0.01 to 0.3. For details of the ratios (Q / P) and (R / P), see the corresponding sections in <Battery manufacturing method>.

[0071] In a preferred embodiment, the total formation area Q of the first adhesive layer 1A is smaller than the total formation area R of the second adhesive layer 1B. For details about the ratio (R / Q), please refer to the corresponding section in <Battery manufacturing method>.

[0072] As described above, in a plan view of the separator 26, the first adhesive layer 1A is partially formed, and the second adhesive layer 1B is partially formed. In a preferred embodiment, the first adhesive layer 1A and the second adhesive layer 1B are formed in a predetermined pattern. For details on the shape of the pattern, etc., please refer to the corresponding section in <Battery Manufacturing Method>.

[0073] In a preferred embodiment, the first adhesive layer 1A and the second adhesive layer 1B are each formed in the shape of a plurality of dots. The diameter D1 of the dots in the first adhesive layer 1A is smaller than the diameter D2 of the dots in the second adhesive layer. For details about the ratio (D1 / D2), please refer to the corresponding section in <Battery Manufacturing Method>.

[0074] 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.

[0075] 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.

[0076] As described above, as shown in FIG. 10 , the positive electrode terminal 30 is electrically connected to the positive electrodes 22 (see FIG. 15 ) 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. 15 ) 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.

[0077] 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.

[0078] <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.

[0079] 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.

[0080] For example, in the above embodiment, the first adhesive layer 1A and the second adhesive layer 1B are formed on the surface of the separator 26 facing the positive electrode 22, but this is not limiting. In other embodiments, the first adhesive layer 1A and the second adhesive layer 1B may be formed on the surface of the separator 26 facing the negative electrode 24. Alternatively, the first adhesive layer 1A and the second adhesive layer 1B may be formed on the surface of the separator 26 facing the positive electrode 22 and the surface of the separator 26 facing the negative electrode 24.

[0081] For example, Fig. 17 is a view corresponding to Fig. 5 according to the second embodiment. As shown in Fig. 17, in the second embodiment, the pattern of the separator 126 has circular dots in a plan view, and the dot diameters of the first adhesive layer 101A and the second adhesive layer 101B are the same. Furthermore, the number of first adhesive layers 101A in the separator 126 is smaller than the number of second adhesive layers 101B. The battery according to the second embodiment may be similar to the battery 100 described above, except for the change in the pattern.

[0082] For example, Fig. 18 is a view corresponding to Fig. 5 according to the third embodiment. As shown in Fig. 18, in the third embodiment, the first adhesive layer 201A and the second adhesive layer 201B of the separator 226 have linear shapes in a plan view that extend along the longitudinal direction Z of the separator 226. The battery according to the third embodiment may be similar to the battery 100 described above, except for the change in pattern.

[0083] For example, Fig. 19 is a view corresponding to Fig. 5 according to the fourth embodiment. As shown in Fig. 19, in the fourth embodiment, the shape of the first adhesive layer 301A and the second adhesive layer 201B of the separator 326 in a plan view is such that lines extending along the longitudinal direction Z of the separator 226 and dots formed along the longitudinal direction Z are alternately formed. With this configuration, the dot-shaped first adhesive layer 301A adheres to the positive electrode 22 at each spaced position during the winding process, and the linear second adhesive layer 301B strongly adheres to the positive electrode 22 during the pressing process. The battery according to the fourth embodiment may be similar to the battery 100 described above, except for the change in pattern.

[0084] For example, Fig. 20 is a view corresponding to Fig. 5 according to the fifth embodiment. As shown in Fig. 20, in the fifth embodiment, the shape of the first adhesive layer 401A and the second adhesive layer 401B of the separator 426 in a plan view is linear and extends along the direction Y orthogonal to the longitudinal direction of the separator 426. The battery according to the fifth embodiment may be similar to the battery 100 described above, except for the change in the pattern.

[0085] In another embodiment, the second adhesive layer 1B may be disposed over the entire surface of the separator 26, and the first adhesive layer 1A may be patterned over a portion of the surface.

[0086] As described above, specific aspects of the technology disclosed herein include those described in the following items. Item 1: 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 separator having a first adhesive layer and a second adhesive layer on at least one of its surfaces, the first adhesive layer being partially formed and the second adhesive layer being partially formed in a plan view of the separator, the first adhesive layer being composed of an adhesive layer that has adhesiveness to the first electrode when it comes into contact with the first electrode facing the first adhesive layer at room temperature, and the second adhesive layer being composed of an adhesive layer that does not have adhesiveness to the first electrode when the first adhesive layer and the facing first electrode are bonded together, but that has adhesiveness to the first electrode when some physical means is subsequently applied. Item 2: The electricity storage device according to item 1, wherein the ratio (Q / P) of the total formation area Q of the first adhesive layer to the area P of one side of the separator is 0.01 to 0.3, and the ratio (R / P) of the total formation area R of the second adhesive layer to the area P of one side of the separator is 0.01 to 0.3. Item 3: The electricity storage device according to item 1 or 2, wherein a total formation area Q of the first adhesive layer is smaller than a total formation area R of the second adhesive layer. Item 4: The electricity storage device according to any one of items 1 to 3, wherein the first adhesive layer and the second adhesive layer are each formed in the shape of a plurality of dots, and the diameter of the dots in the first adhesive layer is smaller than the diameter of the dots in the second adhesive layer. Item 5: 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, the method 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 the winding step uses the separator having a first adhesive layer and a second adhesive layer on at least one of its surfaces, and in a plan view of the separator, the first adhesive layer is partially formed and the second adhesive layer is partially formed, a main component of the resin constituting the first adhesive layer is different from a main component of the resin constituting the second adhesive layer, and under temperature conditions in the winding step, the adhesiveness of the second adhesive layer to the first electrode is weaker than the adhesiveness of the first adhesive layer to the first electrode. Item 6: A method for manufacturing an electricity storage device according to Item 5, wherein the first adhesive layer is composed of an adhesive layer that has adhesive properties to the first electrode when it comes into contact with the first electrode opposite the first adhesive layer at room temperature, and the second adhesive layer is composed of an adhesive layer that does not have adhesive properties to the first electrode when the first adhesive layer and the opposite first electrode are bonded together, but that has adhesive properties to the first electrode when some physical means is subsequently applied. Item 7: The method for producing an electricity storage device according to Item 5 or Item 6, wherein the winding step is carried out under conditions of 50° C. or less. Item 8: The method for manufacturing an electricity storage device according to any one of Items 5 to 7, wherein in the separator used in the winding step, the ratio (Q / P) of the total formation area Q of the first adhesive layer to the area P of one side of the separator is 0.01 to 0.3, and the ratio (R / P) of the total formation area R of the second adhesive layer to the area P of one side of the separator is 0.01 to 0.3. Item 9: The method for manufacturing an electricity storage device according to any one of Items 5 to 8, wherein in the separator used in the winding step, a total formation area Q of the first adhesive layers is smaller than a total formation area R of the second adhesive layers. Item 10: The method for manufacturing an electricity storage device according to any one of Items 5 to 9, wherein in the separator used in the winding step, the first adhesive layer and the second adhesive layer are each formed in the shape of a plurality of dots, and the diameter of the dots in the first adhesive layer is smaller than the diameter of the dots in the second adhesive layer. [Explanation of symbols]

[0087] 1A,1B Adhesive layer 10 Battery case 12 Exterior body 14 Sealing plate 15 Liquid injection hole 15a Sealing member 16 Insulation groove 17 Gas exhaust valve 18,19 Terminal insertion holes 20 Electrode group 20a to 20c Wound 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 A Conveyor roller B Winding core C press machine

Claims

1. 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 separator has a first adhesive layer and a second adhesive layer on at least one of its surfaces, In a plan view of the separator, the first adhesive layer is partially formed; the second adhesive layer is partially formed; The first adhesive layer is the adhesive layer is configured to have adhesiveness to the first electrode by contacting the first electrode facing the first adhesive layer at room temperature, The second adhesive layer is An electricity storage device comprising an adhesive layer that does not have adhesive properties to the first electrode when the first adhesive layer and the opposing first electrode are bonded together, but that subsequently gains adhesive properties to the first electrode when at least one of heating and pressure is applied.

2. a ratio (Q / P) of a total formation area Q of the first adhesive layer to an area P of one surface of the separator is 0.01 to 0.3; 2. The electricity storage device according to claim 1, wherein a ratio (R / P) of a total formation area R of the second adhesive layer to an area P of one side of the separator is 0.01 to 0.

3.

3. The electricity storage device according to claim 1 , wherein a total formation area Q of the first adhesive layer is smaller than a total formation area R of the second adhesive layer.

4. the first adhesive layer and the second adhesive layer are each formed in a plurality of dots, The power storage device according to claim 1 , wherein a diameter of the dots in the first adhesive layer is smaller than a diameter of the dots in the second adhesive layer.

5. 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, after the winding step, press-forming the wound body into a flat wound electrode body, In the winding step, the separator having a first adhesive layer and a second adhesive layer on at least one of its surfaces is used, In a plan view of the separator, the first adhesive layer is partially formed; the second adhesive layer is partially formed; a main component of the resin constituting the first adhesive layer is different from a main component of the resin constituting the second adhesive layer, Under the temperature conditions in the winding step, The adhesiveness of the second adhesive layer to the first electrode is the adhesiveness of the first adhesive layer is less than that of the first electrode; The first adhesive layer is the adhesive layer is configured to have adhesiveness to the first electrode by contacting the first electrode facing the first adhesive layer at room temperature, The second adhesive layer is A method for manufacturing an electricity storage device, comprising an adhesive layer that does not have adhesiveness to the first electrode when the first adhesive layer and the opposing first electrode are bonded together, and that then has adhesiveness to the first electrode when at least one of heating and pressure is applied.

6. The method for manufacturing an electricity storage device according to claim 5 , wherein the winding step is performed under conditions of 50° C. or less.

7. In the separator used in the winding step, a ratio (Q / P) of a total formation area Q of the first adhesive layer to an area P of one surface of the separator is 0.01 to 0.3; 7. The method for manufacturing an electricity storage device according to claim 5, wherein a ratio (R / P) of a total formation area R of the second adhesive layer to an area P of one side of the separator is 0.01 to 0.

3.

8. In the separator used in the winding step, The method for manufacturing an electricity storage device according to claim 5 or 6, wherein a total formation area Q of the first adhesive layer is smaller than a total formation area R of the second adhesive layer.

9. In the separator used in the winding step, the first adhesive layer and the second adhesive layer are each formed in a plurality of dots, The method for manufacturing an electricity storage device according to claim 5 , wherein a diameter of the dots in the first adhesive layer is smaller than a diameter of the dots in the second adhesive layer.

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