Method for manufacturing a wound electrode body, method for manufacturing an electricity storage device including the wound electrode body, and apparatus for manufacturing the wound electrode body

Abstract

To provide a technique capable of suitably improving the productivity of a wound electrode body and a battery including the wound electrode body.SOLUTION: A manufacturing method for a wound electrode body disclosed herein includes a preparation step (S1) of preparing a positive electrode sheet 22, a negative electrode sheet 24, and a separator sheet 26, in which an adhesive layer 6 is disposed on both sides in the separator sheet 26 (here, a second separator sheet 26S2) of each of the sheets, a transport step (S2) of transporting each of the prepared sheets, in which the area of the second separator sheet 26S2 with the adhesive layer 6 disposed thereon, where the adhesive layer 6 is not disposed, is transported while making rollers 3a and 3b abut thereon, and a winding step (S3) of winding each of the transported sheets around a winding core 4.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present disclosure relates to a method for manufacturing a wound electrode body, a method for manufacturing an electricity storage device including the wound electrode body, and an apparatus for manufacturing the wound electrode body. [Background technology]

[0002] For example, Patent Document 1 discloses a method for manufacturing a wound electrode body, which is formed by spirally winding a strip-shaped positive electrode sheet, a strip-shaped negative electrode sheet, and a strip-shaped separator sheet interposed between them, characterized in that at least one of the positive electrode sheet, the negative electrode sheet, and the separator sheet is wound while continuously removing foreign matter adhering to the constituent sheets in a non-contact state. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-152946 Summary of the Invention [Problem to be solved by the invention]

[0004] Recently, to prevent the electrode sheet and separator sheet in a wound electrode body from shifting, an adhesive layer is sometimes disposed on the surface of the electrode sheet and / or separator sheet. The inventors' investigations have revealed that, for example, when a wound electrode body is manufactured using an electrode sheet or separator sheet on which an adhesive layer is disposed, the adhesive layer may adhere to rollers (guide rollers) disposed in a transport path that transports the sheet on which the adhesive layer is disposed to the winding core. This is undesirable from the viewpoint of productivity, as it may result in the adhesion of foreign matter to the sheet or a decrease in the adhesive strength of the adhesive layer.

[0005] The present disclosure has been made in consideration of these circumstances, and its main purpose is to provide a technology that can suitably improve the productivity of a wound electrode body having an electrode sheet with an adhesive layer or a separator sheet, and an electricity storage device including the wound electrode body. [Means for solving the problem]

[0006] To achieve this objective, the present disclosure provides a method for manufacturing a wound electrode assembly in which a strip-shaped positive electrode sheet and a strip-shaped negative electrode sheet are stacked and wound with a strip-shaped separator sheet interposed therebetween, the separator sheet and the positive electrode sheet and / or the separator sheet and the negative electrode sheet are bonded together with an adhesive layer, the method comprising the following steps: a preparation step of preparing the positive electrode sheet, the negative electrode sheet, and the separator sheet, wherein the adhesive layer is disposed on at least one side of at least one of the sheets; a transport step of transporting the prepared sheets, wherein the adhesive-layer-deposited sheet is transported while being brought into contact with a roller in an area where the adhesive layer is not disposed; and a winding step of winding the transported sheets around a core. As will be described in detail below, this method for manufacturing a wound electrode assembly allows for high productivity of wound electrode assembly production.

[0007] From another aspect, the present disclosure provides a method for manufacturing an electricity storage device, in which an electricity storage device is constructed using a wound electrode body obtained by any of the methods for manufacturing a wound electrode body disclosed herein. By using this method for manufacturing an electricity storage device, it is possible to produce an electricity storage device including a wound electrode body with high productivity.

[0008] From another aspect, there is provided a manufacturing apparatus for a wound electrode body in which a strip-shaped positive electrode sheet and a strip-shaped negative electrode sheet are stacked and wound with a strip-shaped separator sheet interposed therebetween, the separator sheet and the positive electrode sheet and / or the separator sheet and the negative electrode sheet being bonded together with an adhesive layer, the manufacturing apparatus for a wound electrode body comprising: a conveying unit that conveys each of the sheets; one or more rollers configured to contact areas of each of the sheets on which the adhesive layer is disposed that are not provided with the adhesive layer; and a winding core that winds up each of the sheets conveyed by the conveying unit. As will be described in detail below, a manufacturing apparatus for a wound electrode body configured in this manner can produce wound electrode bodies with high productivity. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a block diagram schematically illustrating a manufacturing apparatus for a wound electrode body according to one embodiment. [Figure 2] 3 is a schematic diagram showing the surface of a second separator sheet according to one embodiment in a plan view and the configuration of a roller. FIG. [Figure 3] 4 is a schematic diagram showing the back surface of a second separator sheet according to one embodiment in a plan view and the configuration of a roller. FIG. [Figure 4A] FIG. 2 is a schematic diagram illustrating a structure of a roller according to an embodiment. [Figure 4B] FIG. 2 is a schematic diagram illustrating a structure of a roller according to an embodiment. [Figure 5] 10 is a flowchart illustrating a method for manufacturing a wound electrode assembly according to one embodiment. [Figure 6] FIG. 1 is a perspective view schematically illustrating a battery according to an embodiment. [Figure 7] FIG. 7 is a schematic vertical cross-sectional view taken along line VII-VII in FIG. 6. [Figure 8] FIG. 7 is a schematic vertical cross-sectional view taken along line VIII-VIII in FIG. 6. [Figure 9] FIG. 7 is a schematic cross-sectional view taken along line IX-IX in FIG. 6. [Figure 10] FIG. 2 is a perspective view schematically showing a wound electrode body attached to a sealing plate. [Figure 11] FIG. 2 is a perspective view schematically showing a wound electrode body to which a positive electrode second current collecting portion and a negative electrode second current collecting portion are attached. [Figure 12] FIG. 2 is a schematic diagram showing the configuration of a wound electrode body of a battery according to one embodiment. [Figure 13] FIG. 2 is an enlarged view schematically illustrating the interfaces between a positive electrode sheet, a negative electrode sheet, and a separator sheet according to one embodiment. [Figure 14] FIG. 10 is a view corresponding to FIG. 2 according to the second embodiment. [Figure 15] FIG. 10 is a view corresponding to FIG. 2 according to a third embodiment. [Figure 16] FIG. 10 is a view corresponding to FIG. 2 according to the fourth embodiment. [Figure 17] FIG. 10 is a view corresponding to FIG. 2 according to the fifth embodiment. [Figure 18] FIG. 10 is a view corresponding to FIG. 2 according to the sixth embodiment. [Figure 19] FIG. 11 is a view corresponding to FIG. 2 according to the seventh embodiment. [Figure 20] FIG. 12 is a view corresponding to FIG. 2 according to the eighth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Several embodiments of the technology disclosed herein will be described below with reference to the drawings. 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 the actual dimensional relationships. Matters other than those specifically mentioned in this specification that are necessary for implementing the technology disclosed herein (e.g., the general configuration and manufacturing process of a battery that do not characterize the present invention) can be understood as design matters of a person skilled in the art based on prior art in the relevant field. The technology disclosed herein can be implemented based on the content disclosed in this specification and common technical knowledge in the relevant field. In this specification, the expression "A to B" indicating a range means "greater than A and less than B." It also encompasses the meanings of "greater than A" and "less than B."

[0011] In this specification, the term "electricity storage device" refers to a device that can be charged and discharged. Electricity storage devices include batteries such as primary batteries and secondary batteries (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. In the following, the present technology will be described using a lithium ion secondary battery, which is one embodiment of an electricity storage device, as an example.

[0012] In the following, an example will be described in which an adhesive layer 6 is disposed on second separator sheet 26S2 out of positive electrode sheet 22, negative electrode sheet 24, and separator sheet 26 (here, first separator sheet 26S1 and second separator sheet 26S2), and further adhesive layers 6 are disposed on both sides of second separator sheet 26S2. Furthermore, in the technology disclosed herein, a sheet (here, second separator sheet 26S2) on which an adhesive layer 6 has been previously disposed can also be used, but the following will describe a case in which an adhesive layer 6 is formed on the surface of a sheet (here, second separator sheet 26S2) by adhesive layer application unit 5. Naturally, it is not intended that the technology disclosed herein be limited to the following embodiments.

[0013] <Wound electrode body manufacturing equipment 1> First, a wound electrode manufacturing apparatus 1 according to this embodiment will be described. Here, Fig. 1 is a block diagram that schematically shows the wound electrode manufacturing apparatus 1 according to this embodiment. The wound electrode manufacturing apparatus 1 is a manufacturing apparatus for wound electrode bodies (here, wound electrode bodies 20a, 20b, 20c) in which a strip-shaped positive electrode sheet 22 and a strip-shaped negative electrode sheet 24 are stacked and wound with a strip-shaped separator sheet 26 interposed therebetween (this can also be referred to as a wound electrode body including a strip-shaped positive electrode sheet 22 and a strip-shaped negative electrode sheet 24 and a separator sheet 26 that insulates these sheets), and in which the separator sheet 26 and the positive electrode sheet 22 and / or the separator sheet 26 and the negative electrode sheet 24 are bonded together by an adhesive layer 6. 1, the wound electrode body manufacturing apparatus 1 according to this embodiment includes a conveying unit 2 that conveys each sheet, one or more rollers (here, rollers 3a and 3b) configured to contact areas of each sheet on which adhesive layer 6 is arranged (here, second separator sheet 26S2) where adhesive layer 6 is not arranged, and a winding core 4 that winds up each of the sheets conveyed by the conveying unit 2. The apparatus further includes an adhesive layer applying unit 5 that applies adhesive layer 6 to at least one surface of at least one of the sheets (here, both surfaces of second separator sheet 26S2).

[0014] With the wound electrode body manufacturing apparatus 1 configured as described above, for example, it is possible to suitably prevent the adhesive layer 6 arranged on the sheet (here, the second separator sheet 26S2) from adhering to the rollers (here, the rollers 3a and 3b). This makes it possible to suitably prevent foreign matter from adhering to the sheet (here, the second separator sheet 26S2) and to prevent a decrease in the adhesive strength of the adhesive layer 6, thereby suitably improving the productivity of wound electrode bodies and electricity storage devices (e.g., batteries) that include the wound electrode bodies.

[0015] The wound electrode manufacturing apparatus 1 preferably includes, for example, a cutter, a presser jig, and a control device. Here, the cutter is a cutter that cuts each of the above-mentioned sheets to a desired length. The presser jig is a jig that presses each of the above-mentioned sheets against the winding core 4. It is preferable that each component of the wound electrode manufacturing apparatus 1 has a required actuator as appropriate. The control device is configured to control each component of the wound electrode manufacturing apparatus 1 so that required operations are performed at predetermined timings in accordance with a preset program. The control device can be embodied by, for example, a computer such as a microcontroller. Each component will be described in detail below.

[0016] (Transportation section 2) As shown in FIG. 1, the conveying unit 2 conveys each of the positive electrode sheet 22, the negative electrode sheet 24, and the separator sheet 26 (here, the first separator sheet 26S1 and the second separator sheet 26S2). The conveying unit 2 conveys each of the sheets to the winding core 4. The sheets can be prepared in a state of being wound around a reel or the like. As shown in FIG. 1, in this embodiment, the positive electrode sheet 22, the negative electrode sheet 24, the first separator sheet 26S1, and the second separator sheet 26S2 are wound around reels 22r, 24r, 26S1r, and 26S2r, respectively. The conveying unit 2 may also include a dancer roll mechanism for removing slack from the positive electrode sheet 22, the negative electrode sheet 24, the first separator sheet 26S1, and the second separator sheet 26S2 being fed out, a tensioner for adjusting the tension, and the like.

[0017] (Roller 3a, 3b) As shown in FIG. 1 , the wound electrode manufacturing apparatus 1 according to this embodiment includes rollers 3a and 3b configured to contact the regions of the second separator sheet 26S2, on which the adhesive layer 6 is disposed, that are not provided with the adhesive layer 6. Here, roller 3a sandwiches the front surface of the second separator sheet 26S2, and roller 3b sandwiches the back surface of the second separator sheet 26S2. The wound electrode manufacturing apparatus 1 according to this embodiment includes two rollers with this configuration; however, in other embodiments, only one roller with this configuration may be provided, or three or more rollers with this configuration may be provided. Furthermore, if the adhesive layer 6 is disposed on the electrode sheet, a roller with this configuration may be used for the electrode sheet. In addition to the rollers with this configuration, rollers for conveying the respective sheets may also be provided. For example, in this embodiment, in addition to rollers 3a and 3b, roller 3c for conveying the first separator sheet 26S1 and the negative electrode sheet 24 is provided. It is sufficient that only the sheet on which at least the adhesive layer 6 is formed is transported by the rollers.

[0018] The wound electrode body manufacturing apparatus 1 disclosed herein may include at least rollers (here, rollers 3a and 3b) configured to contact the area of ​​the sheet (here, second separator sheet 26S2) on which adhesive layer 6 is disposed, where adhesive layer 6 is not disposed. Regarding the relationship between the area on which adhesive layer 6 is disposed and the rollers (here, rollers 3a and 3b), when the entire area of ​​adhesive layer 6 on one side of the sheet (here, second separator sheet 26S2) is taken as 100%, the area ratio of contact between roller 3a (roller 3b) and adhesive layer 6 is preferably, for example, 40% or less, more preferably 30% or less, and particularly preferably 20% or less, from the viewpoint of more suitably suppressing adhesion of foreign matter to the sheet (here, second separator sheet 26S2) and a decrease in the adhesive strength of adhesive layer 6. However, this is not limited thereto. Furthermore, when the adhesive layer 6 and the roller 3a (roller 3b) are in slight contact with each other, the adhesive layer 6 may be in contact with the end 3a3 (end 3b3) of the roller 3a (roller 3b) in the TD direction (see Figures 4A and 4B).

[0019] In one embodiment, the adhesive layer is intermittently arranged on the short or long sides of the sheet, and the roller is configured to contact the area of ​​the sheet where the adhesive layer is not intermittently arranged. FIG. 2 is a schematic diagram showing the front surface of the second separator sheet 26S2 in a plan view and the configuration of roller 3a. FIG. 3 is a schematic diagram showing the back surface of the second separator sheet 26S2 in a plan view and the configuration of roller 3b. As shown in FIGS. 2 and 3, in this embodiment, the adhesive layer 6 is intermittently arranged on both sides of the second separator sheet 26S2 along the long sides of the second separator sheet 26S2. The rollers 3a and 3b are configured to contact the area of ​​the second separator sheet 26S2 where the adhesive layer 6 is not arranged.

[0020] In this embodiment, the second separator sheet 26S2 has a dashed line shape in plan view, but is not limited thereto. The shape of the adhesive layer 6 in plan view of the second separator sheet 26S2 may be, for example, a dotted shape, a striped shape, a wavy shape, a band (stripe shape), or a combination thereof. For example, the second to eighth embodiments described below provide other examples of the shape of the adhesive layer 6 in plan view of the sheet. In addition, in this embodiment, the number of intermittent lines arranged on the front and back sides of the second separator sheet 26S2 is different, but in other embodiments, the number may be the same. That is, the positions of the adhesive layer 6 may be the same on the front and back sides of the sheet, or may be different. In addition, the number of intermittent lines arranged on one side of the second separator sheet 26S2 may be one or more. In the present embodiment, the adhesive layer 6 is disposed on the long side of the second separator sheet 26S2, but is not limited to this. The adhesive layer 6 may be disposed on the short side of the second separator sheet 26S2.

[0021] In one embodiment, the rotating surface of the roller is configured in a comb shape with alternating concave and convex portions, and the convex portions are configured to abut against areas of the sheet on which the adhesive layer is disposed, where the adhesive layer is not disposed. FIGS. 4A and 4B are schematic diagrams showing the structures of rollers 3a and 3b, respectively. As shown in FIG. 4A, in this embodiment, the rotating surface of roller 3a is configured in a comb shape with alternating concave and convex portions 3a1 and 3a2. Similarly, the rotating surface of roller 3b is configured in a comb shape with alternating concave and convex portions 3b1 and 3b2. The convex portions 3a2 and 3b2 are configured to abut against areas of the second separator sheet 26S2 on which the adhesive layer 6 is disposed, where the adhesive layer 6 is not disposed. The shape of the rotating surface of the roller is not limited to a comb shape and may be any other shape as long as the effects of the technology disclosed herein are obtained. For example, the edges of rollers 3a and 3b may be rounded. This configuration can suitably prevent the edge portion from coming into contact with the adhesive layer 6. For example, the rollers 3a and 3b, each having a comb-shaped rotating surface, and the roller 3d described below can hold (sandwich) the conveyed sheet with sufficient strength between both end portions of each roller.

[0022] In a preferred embodiment, the roller is configured so that the roller does not substantially contact an area of ​​the sheet on which the adhesive layer is disposed, where the adhesive layer is disposed. As shown in FIG. 2, in this embodiment, roller 3a is configured so that the roller 3a does not substantially contact an area of ​​the second separator sheet 26S2 on which the adhesive layer 6 is disposed, where the adhesive layer 6 is disposed. Also, as shown in FIG. 3, in this embodiment, roller 3b is configured so that the roller 3b does not substantially contact an area of ​​the second separator sheet 26S2 on which the adhesive layer 6 is disposed, where the adhesive layer 6 is disposed. This configuration can particularly effectively prevent foreign matter from adhering to the sheet (here, the second separator sheet 26S2) and a decrease in the adhesive strength of the adhesive layer 6, thereby making it possible to preferably improve the productivity of the wound electrode body and an electricity storage device (e.g., a battery) including the wound electrode body. Here, the area where the adhesive layer 6 is arranged and the roller 3a (roller 3b) do not substantially come into contact means that, for example, when the total area of ​​the adhesive layer 6 on one side of the sheet (here, the second separator sheet 26S2) is taken as 100%, the area ratio where the roller 3a (roller 3b) and the adhesive layer 6 come into contact is, for example, 10% or less, preferably 5% or less, more preferably 1% or less, and particularly preferably 0% (i.e., the sheet and the roller do not come into contact at all).

[0023] (Core 4) As shown in Fig. 1, the winding core 4 winds up each of the sheets transported by the transport unit 2. The winding core 4 has a function of holding each of the sheets wound around its circumferential surface. In this example, the winding core 4 is a substantially cylindrical member, but a flat winding core may be used when winding into a flat shape.

[0024] (Adhesive layer application section 5) The adhesive layer applicator 5 is a device for disposing (applying) the adhesive layer to at least one surface of at least one of the sheets. The adhesive layer applicator 5 can also be referred to as a device for applying a binder liquid (adhesive) to the surface of a sheet along the conveying direction. As described above, in this embodiment, the adhesive layer applicator 5 disposes adhesive layers 6 on both surfaces of the second separator sheet 26S2. The adhesive layer applicator 5 is configured to apply a desired amount of binder liquid to a desired area of ​​the sheet. The binder liquid contains, for example, an adhesive layer binder as described below and a solvent. A so-called aqueous solvent is preferably used as the solvent for the binder liquid from the viewpoint of reducing environmental impact. In this case, water or a mixed solvent mainly composed of water can be used. As the solvent component other than water that constitutes such a mixed solvent, one or more organic solvents (e.g., lower alcohols, lower ketones) that are uniformly miscible with water can be appropriately selected and used. For example, it is preferable to use an aqueous solvent in which 80% by mass or more (more preferably 90% by mass or more, and even more preferably 95% by mass or more) of the aqueous solvent is water. A particularly preferable example is an aqueous solvent that is substantially composed of water. The solvent for the binder liquid is not limited to so-called aqueous solvents, and may be so-called organic solvents. Examples of organic solvents include N-methylpyrrolidone. For example, a suitable example of the binder liquid is one in which water is used as the solvent and an acrylic resin (e.g., polymethacrylic acid ester resin) is mixed as the binder. Note that the binder liquid may contain one or more additives, such as known thickeners or surfactants, for the purpose of improving the wettability of the positive electrode sheet 22 and the separator sheet 26, as long as the effects of the technology disclosed herein are not impaired.

[0025] As the adhesive layer application section 5, various application devices can be used, for example, inkjet printing, various gravure roll coaters, spray coaters, etc., die coaters such as slit coaters, comma coaters, and cap coaters (Capillary Coaters (CAP coaters), lip coaters, calenders, etc.

[0026] Although not particularly limited, the area of ​​the adhesive layer 6 on one side of the sheet is, for example, 5% or more when the area of ​​one side of the sheet is taken as 100%, and from the viewpoint of more favorable adhesion between the electrode sheet and the separator sheet in the wound electrode body (here, wound electrode bodies 20a, 20b, and 20c), it is preferably 10% or more, or may be 20% or more, or 30% or more. Furthermore, the upper limit of the area of ​​the adhesive layer 6 on one side of the sheet is, for example, 60% or less, and may be 50% or less, or 40% or less.

[0027] Next, a preferred embodiment of a method for manufacturing a wound electrode body (a battery including a wound electrode body) according to this embodiment will be described, along with a wound electrode body manufacturing apparatus 1 that embodies the method for manufacturing a wound electrode body. Here, FIG. 5 is a flowchart showing the method for manufacturing a wound electrode body according to this embodiment. First, the manufacturing method according to this embodiment is a method for manufacturing a wound electrode body (here, wound electrode bodies 20a, 20b, 20c) in which a strip-shaped positive electrode sheet 22 and a strip-shaped negative electrode sheet 24 are stacked with a strip-shaped separator sheet 26 interposed therebetween and wound (this can also be referred to as a wound electrode body including a strip-shaped positive electrode sheet 22 and a strip-shaped negative electrode sheet 24 and a separator sheet 26 that insulates these sheets), and in which the separator sheet 26 and the positive electrode sheet 22 and / or the separator sheet 26 and the negative electrode sheet 24 are bonded by an adhesive layer 6. The method for manufacturing such a wound electrode body includes a preparation step (step S1) of preparing a positive electrode sheet 22, a negative electrode sheet 24, and a separator sheet 26; a conveying step (step S2) of conveying each of the prepared sheets; and a winding step (step S3) of winding each of the conveyed sheets around a winding core 4. In the preparation step, at least one of the sheets is prepared with an adhesive layer 6 disposed on at least one side (here, both sides of the second separator sheet 26S2). In the conveying step, the sheet with the adhesive layer 6 (here, the second separator sheet 26S2) is conveyed while the region where the adhesive layer 6 is not disposed is brought into contact with rollers (here, rollers 3a and 3b).

[0028] According to the manufacturing method of the wound electrode body having such a configuration, it is possible to suitably prevent the adhesive layer 6 arranged on the sheet (here, the second separator sheet 26S2) from adhering to the rollers (here, the rollers 3a and 3b). This suitably prevents foreign matter from adhering to the sheet (here, the second separator sheet 26S2) and a decrease in the adhesive strength of the adhesive layer 6, thereby suitably improving the productivity of the wound electrode body and the electricity storage device (e.g., battery) including the wound electrode body. Each step will be described in detail below. Note that the manufacturing method of the battery disclosed herein may further include other steps at any stage, and if a step is not described as essential, it can be deleted as appropriate. Furthermore, the order of the steps can be changed as long as the effects of the technology disclosed herein are exhibited.

[0029] <Step S1: Preparation Process> As described above, in this step, the positive electrode sheet 22, the negative electrode sheet 24, and the separator sheet 26 are prepared. In this embodiment, a first separator sheet 26S1 and a second separator sheet 26S2 are prepared as separator sheets. As shown in FIGS. 2 and 3 , in this embodiment, the sheet on which the adhesive layer 6 is disposed is the separator 26 (specifically, the second separator sheet 26S2). Note that in other embodiments, the sheet on which the adhesive layer 6 is disposed may be the positive electrode sheet 22 or the negative electrode sheet 24. Alternatively, the adhesive layer 6 may be disposed on two or more sheets selected from the positive electrode sheet 22, the negative electrode sheet 24, and the separator sheet 26 (here, the first separator sheet 26S1 and the second separator sheet 26S2). Furthermore, in this embodiment, the adhesive layer 6 is disposed on both sides of the second separator sheet 26S2. This configuration can more effectively prevent the electrode sheet and separator sheet in the wound electrode body from becoming misaligned. Alternatively, it can be said that a sheet with this configuration is suitable for application of the technology disclosed herein. Note that in other embodiments, the adhesive layer 6 may be disposed on only one side of the sheet (here, the second separator sheet 26S2).

[0030] In a preferred embodiment, the adhesive layer is formed on at least one surface of at least one of the sheets in the preparation step. As shown in Figures 2 and 3, in this embodiment, the adhesive layer 6 is formed on both surfaces of the second separator sheet 26S2 in the preparation step. This configuration is preferable because it can suppress deterioration of the adhesive layer 6 and ensure adhesive strength better than when using a sheet (here, the second separator sheet 26S2) on which the adhesive layer 6 is already arranged.

[0031] <Step S2: Transporting Process> As described above, in this step, the prepared sheets are conveyed while being sandwiched between rollers 3a and 3b. Also, this conveying step is characterized in that the area of ​​second separator sheet 26S2 on which adhesive layer 6 is arranged, where adhesive layer 6 is not arranged, is brought into contact with rollers 3a and 3b.

[0032] In a preferred aspect, in the conveying step, the region of the sheet on which the adhesive layer is disposed is kept substantially out of contact with the rollers. As shown in Figures 2 and 3, in this embodiment, in the conveying step, the region of the second separator sheet 26S2 on which the adhesive layer 6 is disposed is kept substantially out of contact with the rollers 3a and 3b. This configuration particularly effectively prevents foreign matter from adhering to the sheet (here, the second separator sheet 26S2) and reduces the adhesive strength of the adhesive layer 6, thereby effectively improving the productivity of the wound electrode body and an electricity storage device (e.g., a battery) including the wound electrode body.

[0033] In one embodiment, the surface of the roller on which the roller rotates is configured in a comb shape with alternating concave and convex portions, and in the conveying step, the convex portions are brought into contact with areas of the sheet on which the adhesive layer is disposed that do not have the adhesive layer, thereby conveying the sheet on which the adhesive layer is disposed. As shown in FIGS. 2 and 3, in this embodiment, the surface on which roller 3a rotates is configured in a comb shape with alternating concave and convex portions 3a1 and 3a2. Similarly, the surface on which roller 3b rotates is configured in a comb shape with alternating concave and convex portions 3b1 and 3b2. In the conveying step, the convex portions 3a2 and 3b2 are brought into contact with areas of the second separator sheet 26S2 on which the adhesive layer 6 is disposed that do not have the adhesive layer 6, thereby conveying the second separator sheet 26S2 on which the adhesive layer 6 is disposed.

[0034] In one aspect, the sheet on which the adhesive layer is disposed has the adhesive layer intermittently disposed on the short or long sides of the sheet, and in the conveying step, the rollers convey the sheet on which the adhesive layer is disposed so as to abut against regions of the sheet on which the adhesive layer is intermittently disposed where the adhesive layer is not disposed. As shown in Figures 2 and 3, in this embodiment, in the second separator sheet 26S2 on which the adhesive layer 6 is disposed, the adhesive layer 6 is intermittently disposed on the long side of the second separator sheet 26S2. Then, in the conveying step, rollers 3a and 3b convey the second separator sheet 26S2 on which the adhesive layer 6 is disposed so as to abut against regions of the second separator sheet 26S2 on which the adhesive layer 6 is intermittently disposed where the adhesive layer 6 is not disposed.

[0035] <Step S3: Winding process> As described above, in this step, the transported positive electrode sheet 22, negative electrode sheet 24, first separator sheet 26S1, and second separator sheet 26S2 are wound around the winding core 4.

[0036] In one aspect, the wound electrode body includes a first separator sheet and a second separator sheet as the separator sheets, and in the winding process, the first separator sheet, the positive electrode sheet, the second separator sheet, and the negative electrode sheet are stacked in this order and wound, or the first separator sheet, the negative electrode sheet, the second separator sheet, and the positive electrode sheet are stacked in this order and wound. As shown in FIG. 1 , in this embodiment, the separator sheets 26 include a first separator sheet 26S1 and a second separator sheet 26S2. In addition, in the winding process, the first separator sheet 26S1, the positive electrode sheet 22, the second separator sheet 26S2, and the negative electrode sheet 24 are stacked in this order and wound. In this manner, a wound electrode body can be obtained.

[0037] Furthermore, in this embodiment, a pressing step may be further provided after the winding step, in which the obtained wound body is pressed. Specifically, the wound body produced as described above is removed from the winding core 4 and pressed by a press or the like. This makes it possible to preferably obtain flat wound electrode bodies 20a, 20b, and 20c. Note that in other embodiments, such a pressing step may not be provided.

[0038] Then, a battery 100 can be constructed using the wound electrode bodies (here, 20a, 20b, and 20c) obtained by the above-described manufacturing method of the wound electrode body. Specifically, the battery 100 can be fabricated by preparing the wound electrode bodies 20a, 20b, and 20c, inserting them into a battery case 10, and sealing the case. First, as shown in FIG. 10, a positive electrode second current collecting portion 52 is joined to the positive electrode tab group 23 of each wound electrode body, and a negative electrode second current collecting portion 62 is joined to the negative electrode tab group 25. Then, as shown in FIG. 9, each wound electrode body is arranged so that its flat portions face each other. A sealing plate 14 is placed above each wound electrode body, and the positive electrode tab group 23 of each wound electrode body is bent so that the positive electrode second current collecting portion 52 faces one side of the wound electrode body. This connects the positive electrode first current collecting portion 51 and the positive electrode second current collecting portion 52. Similarly, the negative electrode tab group 25 of each wound electrode body is bent so that the negative electrode second current collecting portion 62 faces the other side surface 20h of the wound electrode body. This connects the negative electrode first current collecting portion 61 and the negative electrode second current collecting portion 62. As a result, the wound electrode body is attached to the sealing plate 14 via the positive electrode current collecting portion 50 and the negative electrode current collecting portion 60. Next, each wound electrode body attached to the sealing plate 14 is covered with an electrode body holder 29 (see FIG. 8 ) and then housed inside the exterior body 12. As a result, the flat portion of each wound electrode body faces the long side wall 12b of the exterior body 12 (i.e., the flat surface of the battery case 10). In addition, the upper curved portion 20r faces the sealing plate 14, and the lower curved portion 20r faces the bottom wall 12a of the exterior body 12. Then, the opening 12h on the top surface of the exterior body 12 is closed with the sealing plate 14, and the exterior body 12 and the sealing plate 14 are joined (welded) to construct the battery case 10. After that, the electrolyte is injected into the battery case 10 through the liquid inlet 15 of the sealing plate 14, and the liquid inlet 15 is closed with the sealing member 15a. In this manner, the battery 100 can be manufactured.

[0039] <Battery configuration> Next, the battery 100 obtained by the above-described manufacturing method will be described.

[0040] FIG. 6 is a perspective view of the battery 100. FIG. 7 is a schematic longitudinal cross-sectional view taken along line VII-VII in FIG. 6. FIG. 8 is a schematic longitudinal cross-sectional view taken along line VIII-VIII in FIG. 9. FIG. 9 is a schematic transverse cross-sectional view taken along line IX-IX in FIG. 6. 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.

[0041] As shown in Fig. 7, the battery 100 includes a battery case (case) 10 and a wound electrode assembly 20. In addition to the battery case 10 and the wound 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 further includes an electrolyte. Here, the battery 100 is a lithium-ion secondary battery.

[0042] The battery case 10 is a housing that houses the wound 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.

[0043] 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. 6 , the exterior body 12 includes a substantially rectangular bottom wall 12a, a pair of first side walls 12c extending upward in a U-shape from a short side of the bottom wall 12a and facing each other, and a pair of second side walls 12b extending upward in a U-shape from a long side of the bottom wall 12a and facing each other. The area of ​​the first side wall 12c is smaller than the area of ​​the second side wall 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 12c and the pair of second side walls 12b. 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 first side walls 12c is joined to a short side of the sealing plate 14, and each of the pair of second side walls 12b is joined to a long side of the sealing plate 14.

[0044] As shown in FIGS. 6 and 7 , 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 wound 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.

[0045] 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. 7 , 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.

[0046] FIG. 10 is a perspective view schematically illustrating a wound electrode assembly 20 attached to a sealing plate 14. In this embodiment, a plurality of (here, three) wound electrode bodies 20a, 20b, and 20c are housed inside the battery case 10. The number of wound electrode bodies housed inside one battery case 10 is not particularly limited and may be one or two or more (plural). As shown in FIG. 7, a positive electrode current collector 50 is disposed on one side of each wound electrode body in the long side direction Y (the left side in FIG. 7), and a negative electrode current collector 60 is disposed on the other side of the long side direction Y (the right side in FIG. 7). The wound electrode bodies 20a, 20b, and 20c are connected in parallel. However, the wound electrode bodies 20a, 20b, and 20c may also be connected in series. 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. 8) made of a resin sheet.

[0047] 12 is a perspective view that schematically shows the wound electrode body 20a. 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.

[0048] 12, the wound electrode body 20a has a positive electrode sheet 22, a negative electrode sheet 24, and a separator sheet 26. In this example, the wound electrode body 20a is a wound electrode body in which a strip-shaped positive electrode sheet 22 and a strip-shaped negative electrode sheet 24 are stacked with two strip-shaped separator sheets 26 interposed therebetween, and wound around a winding axis WL.

[0049] 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. 8, 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 12b of the exterior body 12. The flat portion 20f extends along the second side wall 12b.

[0050] As shown in FIG. 12, the positive electrode sheet 22 includes a positive electrode current collector 22c, a positive electrode active material layer 22a, and a positive electrode protective layer 22p fixed 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.

[0051] A plurality of positive electrode tabs 22t are provided at one end of the positive electrode current collector 22c in the long side direction Y (the left end in FIG. 12). The plurality of positive electrode tabs 22t are provided at intervals (intermittently) along the longitudinal direction of the strip-shaped positive electrode sheet 22. The plurality of positive electrode tabs 22t protrude outward from the separator sheet 26 toward one axial side of the winding axis WL (the left side in FIG. 12). The positive electrode tabs 22t may be provided on the other axial side of the winding axis WL (the right side in FIG. 12) or on both axial sides of the winding axis WL. The positive electrode tabs 22t are part of the positive electrode current collector 22c and are made of metal foil (aluminum foil). However, the positive electrode tabs 22t may be a separate member from the 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.

[0052] As shown in FIG. 9 , the positive electrode tabs 22t are stacked at one axial end of the winding axis WL (the left end in FIG. 9 ) 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. 7 , 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. 9 ). 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. 12 ) 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.

[0053] As shown in FIG. 12, 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).

[0054] As shown in FIG. 12, 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. 12) 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% by mass, the inorganic filler may account for approximately 50% by mass or more, typically 70% by mass or more, for example, 80% by mass or more. The positive electrode protective layer 22p may also contain optional components other than the inorganic filler, such as a conductive material, a binder, and various additive components. The conductive material and binder may be the same as those exemplified as those that may be contained in the positive electrode active material layer 22a.

[0055] As shown in FIG. 12, the negative electrode sheet 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.

[0056] A plurality of negative electrode tabs 24t are provided at one axial end (the right end in FIG. 12 ) 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 sheet 24. Each of the plurality of negative electrode tabs 24t protrudes outward from the separator sheet 26 toward one axial end (the right end in FIG. 12 ). However, the negative electrode tab 24t may be provided at the other axial end (the left end in FIG. 12 ) 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.

[0057] As shown in FIG. 9 , the negative electrode tabs 24t are stacked at one axial end (the right end in FIG. 9 ) to form a negative electrode tab group 25. The negative electrode tab group 25 is preferably provided symmetrically to the positive electrode tab group 23 in the axial direction. The negative electrode tabs 24t are bent so that their outer ends are aligned. This improves the fitment into the battery case 10 and enables the battery 100 to be made more compact. As shown in FIG. 7 , the negative electrode tab group 25 is electrically connected to the negative electrode terminal 40 via a negative electrode current collecting portion 60. Specifically, the negative electrode tab group 25 and a negative electrode second current collecting portion 62 are connected at a connection portion J (see FIG. 9 ). The negative electrode second current collecting portion 62 is electrically connected to the negative electrode terminal 40 via a negative electrode first current collecting portion 61. As with the positive electrode tabs 22t, the negative electrode tabs 24t are different in size so that their outer ends are aligned when bent.

[0058] As shown in FIG. 12, 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).

[0059] As shown in FIGS. 12 and 3, the separator sheet 26 is a strip-shaped member. The separator sheet 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 sheet 26 is greater than the width of the negative electrode active material layer 24a. By interposing the separator sheet 26 between the positive electrode sheet 22 and the negative electrode sheet 24, contact between the positive electrode sheet 22 and the negative electrode sheet 24 is prevented and charge carriers (e.g., lithium ions) can be transferred between the positive electrode sheet 22 and the negative electrode sheet 24. Although not particularly limited, the thickness of the separator sheet 26 (the length in the stacking direction MD in FIG. 13; the same applies hereinafter) is preferably 3 μm or more, more preferably 5 μm or more. The thickness of the separator sheet 26 is preferably 25 μm or less, more preferably 18 μm or less, and even more preferably 14 μm or less.

[0060] Here, two separator sheets 26 are used per wound electrode body 20a. Preferably, as in this embodiment, two separator sheets 26 are included per wound electrode body 20a, i.e., a first separator and a second separator. Here, the two separators have different configurations, but they may also be the same. However, in other embodiments, only one separator 26 may be included per wound electrode body 20a. In such a case, for example, a positive electrode sheet 22 having insulating layers on both sides, a negative electrode sheet 24, and a separator sheet 26 may be stacked in this order.

[0061] 13 is an enlarged view schematically illustrating the interfaces between the positive electrode sheet 22, the negative electrode sheet 24, and the separator sheet 26 according to this embodiment. As shown in FIG. 13, the separator sheet 26 according to this embodiment has a base layer 27 and a heat resistance layer (HRL) 28 provided on one surface of the base layer 27. An adhesive layer 6 is also present on the surface of the heat resistance layer 28.

[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 sheet 26, and facilitates the production of the wound electrode body 20a (winding and press molding). 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 sheet 22. This more effectively suppresses thermal shrinkage of the separator sheet 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 sheet 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 sheet 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 known in the art for this type of application can be used without any particular limitation. Specific examples include acrylic resins, fluorine-based resins (e.g., PVdF), epoxy resins, urethane resins, and ethylene vinyl acetate resins. Among these, acrylic resins are preferred.

[0067] As shown in FIG. 13 , in this embodiment, the adhesive layer 6 is provided on the surface facing the positive electrode sheet 22 and the surface facing the negative electrode sheet 24, and is in contact with the positive electrode sheet 22 and the negative electrode sheet 24. As shown in FIG. 13 , the adhesive layer 6 is preferably formed at least on the surface of the separator sheet 26 facing the positive electrode sheet 22. Here, the adhesive layer 6 is provided on the heat-resistant layer 28. The adhesive layer 6 is preferably formed on the heat-resistant layer 28. The adhesive layer 6 may be provided directly on the surface of the heat-resistant layer 28, or may be provided on the heat-resistant layer 28 via another layer. The adhesive layer 6 may be provided directly on the surface of the base layer 27, or may be provided on the base layer 27 via a layer other than the heat-resistant layer 28. The adhesive layer 6 may have a relatively higher affinity with the electrolyte solution than, for example, the heat-resistant layer 28, and may be a layer that absorbs the electrolyte solution and swells. Although not particularly limited, the thickness of adhesive layer 6 in wound electrode body 20a (length in stacking direction MD in FIG. 13) is preferably 0.1 μm or more, more preferably 0.2 μm or more, and even more preferably 0.5 μm or more. Furthermore, the thickness of adhesive layer 6 is preferably 10 μm or less, preferably 5 μm or less, and more preferably 3 μm or less. That is, the thickness of adhesive layer 6 in wound electrode body 20a is preferably within the range of 0.1 μm to 10 μm, for example.

[0068] The adhesive layer 6 contains an adhesive layer binder. Any conventionally known resin material having a certain viscosity relative to the positive electrode sheet 22 can be used as the adhesive layer binder without any particular limitations. Specific examples include acrylic resins, fluorine-based resins, epoxy resins, urethane resins, ethylene vinyl acetate resins, polyallylamine (PAA) resins, and cellulose-based resins such as carboxymethyl cellulose (CMC). Fluorine-based resins and acrylic resins are preferred because they have high flexibility and can more suitably exhibit adhesiveness to the positive electrode sheet 22. Examples of fluorine-based resins include polyvinylidene fluoride (PVdF) and polytetrafluoroethylene (PTFE). The type of adhesive layer binder may be the same as or different from the heat-resistant layer binder. The proportion of the heat-resistant layer binder relative to the total mass of the adhesive layer 6 is preferably 20% by mass or more, more preferably 50% by mass or more, and even more preferably 70% by mass or more. This allows the separator sheet 26 to exhibit a predetermined adhesive property to the positive electrode sheet 22 accurately, and also makes it easier for the separator sheet 26 to deform during press molding.

[0069] The adhesive layer 6 may contain other materials (for example, inorganic fillers listed as components of the heat-resistant layer 28) in addition to the adhesive layer binder. When the adhesive layer 6 contains an inorganic filler, the proportion of the inorganic filler relative to the total mass of the adhesive layer 6 is preferably 80 mass % or less, more preferably 50 mass % or less, and even more preferably 30 mass % or less.

[0070] 12, in this embodiment, the adhesive layers 6 are arranged intermittently on the longitudinal line of the second separator sheet 26S2. In this embodiment, the adhesive layers 6 are arranged in a dashed line on the longitudinal line of the second separator sheet 26S2. Note that the shape of the adhesive layers 6 is not limited to this, and may be, for example, dotted, striped, wavy, banded (stripe), or a combination thereof when viewed from above the separator sheet 26.

[0071] 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 wound electrode assembly 20.

[0072] As shown in FIG. 7 , 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. 7 ). The positive electrode terminal 30 is preferably made of metal, more preferably aluminum or an aluminum alloy, for example. 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. 7 ). The negative electrode terminal 40 is preferably made of metal, more preferably copper or a copper alloy, for example. 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. 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.

[0073] As described above, as shown in FIG. 7 , the positive electrode terminal 30 is electrically connected to the positive electrode sheets 22 (see FIG. 12 ) 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. 7, the negative electrode terminal 40 is electrically connected to the negative electrode sheet 24 (see FIG. 12) 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 of the sealing plate 14. The external insulating member 92 can insulate the external conductive members 32, 42 from the sealing plate 14.

[0074] 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.

[0075] <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.

[0076] Although one embodiment of the present disclosure has been described above, the above embodiment (first 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.

[0077] For example, Fig. 14 is a view corresponding to Fig. 2 according to the second embodiment. As shown in Fig. 14, in the second embodiment, in a plan view of a sheet (here, the second separator sheet 126), the adhesive layer 106 is arranged in a band-like (stripe-like) shape along the longitudinal line. The second embodiment may be the same as the first embodiment described above, except for the change in the pattern.

[0078] For example, Fig. 15 is a view corresponding to Fig. 2 according to the third embodiment. As shown in Fig. 15, in the second embodiment, in a plan view of a sheet (here, second separator sheet 226), adhesive layer 206 has an inclined dashed line arranged along the longitudinal line. The third embodiment may be similar to the first embodiment described above, except for the change in the pattern.

[0079] For example, Fig. 16 is a view corresponding to Fig. 2 according to the fourth embodiment. In the second embodiment, in a plan view of a sheet (here, second separator sheet 326), adhesive layer 306 is arranged in a dot pattern along the longitudinal line. The fourth embodiment may be the same as the first embodiment described above, except for the change in the pattern.

[0080] For example, Fig. 17 is a view corresponding to Fig. 2 according to the fifth embodiment. In the fifth embodiment, in a plan view of a sheet (here, second separator sheet 426), adhesive layer 406 is arranged in a band-like shape (stripe-like shape) that gradually becomes thicker along the longitudinal direction. The fifth embodiment may be similar to the first embodiment described above, except for the change in the pattern.

[0081] For example, Fig. 18 is a view corresponding to Fig. 2 according to the second embodiment. In the sixth embodiment, in a plan view of a sheet (here, second separator sheet 526), ​​adhesive layer 506 is arranged in a strip shape (stripe shape) that gradually narrows along the longitudinal direction. The sixth embodiment may be similar to the first embodiment described above, except for the change in pattern.

[0082] For example, Fig. 19 is a view corresponding to Fig. 2 according to the second embodiment. In the seventh embodiment, the adhesive layers 606 are arranged intermittently on the short lines in a plan view of the sheet (here, the second separator sheet 626). The seventh embodiment may be the same as the first embodiment described above, except for the change in the pattern.

[0083] For example, FIG. 20 is a view corresponding to FIG. 2 according to the second embodiment. In the eighth embodiment, in a plan view of a sheet (here, the second separator sheet 726), the adhesive layer 706 is arranged in a strip-like (stripe) pattern on the short line. The eighth embodiment may be similar to the first embodiment described above, except for changing the pattern. In the eighth embodiment, it is preferable that the rotating surface of the roller 3d has a convex portion 3d1 configured to come into contact with an area of ​​the sheet (here, the separator sheet 726) on which the adhesive layer 706 is arranged, where the adhesive layer 706 is not arranged. Furthermore, it is preferable that the sheet (here, the separator sheet 726) on which the adhesive layer 706 is arranged has a concave portion 3d2 configured to prevent the roller 3d from coming into contact with an area of ​​the sheet (here, the separator sheet 726) on which the adhesive layer 706 is arranged.

[0084] As described above, specific aspects of the technology disclosed herein include those described in the following items. Item 1: A method for manufacturing a wound electrode body in which a strip-shaped positive electrode sheet and a strip-shaped negative electrode sheet are stacked with a strip-shaped separator sheet interposed therebetween and wound, wherein the separator sheet and the positive electrode sheet, and / or the separator sheet and the negative electrode sheet are bonded together with an adhesive layer, the method comprising the following steps: a preparation step of preparing the positive electrode sheet, the negative electrode sheet, and the separator sheet, wherein the adhesive layer is disposed on at least one surface of at least one of the sheets; a transport step of transporting each of the prepared sheets, wherein the sheet with the adhesive layer disposed thereon is transported while a region where the adhesive layer is not disposed is brought into contact with a roller; and a winding step of winding each of the transported sheets around a winding core. Item 2: The method for manufacturing a wound electrode body according to Item 1, wherein in the conveying step, the area of ​​the sheet on which the adhesive layer is disposed is prevented from substantially contacting the roller. Item 3: The method for producing a wound electrode body according to Item 1 or 2, wherein in the preparing step, the adhesive layer is formed on at least one surface of at least one of the sheets. Item 4: The method for producing a wound electrode body according to any one of Items 1 to 3, wherein the sheet on which the adhesive layer is disposed is the separator sheet. Item 5: The method for producing a wound electrode body according to Item 4, wherein the adhesive layer is disposed on both sides of the separator sheet. Item 6: The method for producing a wound electrode body according to any one of Items 1 to 5, wherein the wound electrode body has a first separator sheet and a second separator sheet as the separator sheets, and in the winding step, the first separator sheet, the positive electrode sheet, the second separator sheet, and the negative electrode sheet are stacked in this order and wound, or the first separator sheet, the negative electrode sheet, the second separator sheet, and the positive electrode sheet are stacked in this order and wound. Item 7: The method for manufacturing a wound electrode body according to any one of Items 1 to 6, wherein the rotating surface of the roller is configured in a comb shape with alternating concave and convex portions, and in the conveying step, the convex portions are brought into contact with areas of the sheet on which the adhesive layer is disposed that do not have the adhesive layer disposed thereon, thereby conveying the sheet on which the adhesive layer is disposed. Item 8: The method for manufacturing a wound electrode body according to any one of Items 1 to 7, wherein in the sheet on which the adhesive layer is arranged, the adhesive layer is arranged intermittently on short lines or long lines of the sheet, and in the conveying step, the roller conveys the sheet on which the adhesive layer is arranged so that the roller abuts against areas of the sheet on which the adhesive layer is arranged intermittently, where the adhesive layer is not arranged. Item 9: A method for producing an electricity storage device, comprising constructing an electricity storage device using a wound electrode body obtained by the method for producing a wound electrode body according to any one of items 1 to 8. Item 10: A manufacturing apparatus for a wound electrode body in which a strip-shaped positive electrode sheet and a strip-shaped negative electrode sheet are stacked with a strip-shaped separator sheet interposed therebetween and wound, the separator sheet and the positive electrode sheet, and / or the separator sheet and the negative electrode sheet being bonded together with an adhesive layer, the manufacturing apparatus for a wound electrode body comprising: a conveying unit that conveys each of the sheets; one or more rollers configured to come into contact with areas of each of the sheets on which the adhesive layer is disposed that are not covered by the adhesive layer; and a winding core that winds up each of the sheets conveyed by the conveying unit. Item 11: The manufacturing device for a wound electrode body according to Item 10, wherein the roller is configured such that the area of ​​the sheet on which the adhesive layer is disposed, where the adhesive layer is disposed, does not substantially come into contact with the roller. Item 12: The manufacturing device for a wound electrode body according to item 10 or 11, further comprising an adhesive layer application unit for disposing the adhesive layer on at least one surface of at least one of the sheets. Item 13: The manufacturing device for a wound electrode body according to any one of Items 10 to 12, wherein the rotating surface of the roller is configured in a comb shape with alternating concave and convex portions, and the convex portions are configured to abut against areas of the sheet on which the adhesive layer is disposed where the adhesive layer is not disposed. Item 14: The manufacturing device for a wound electrode body according to any one of items 10 to 13, wherein in the sheet on which the adhesive layer is arranged, the adhesive layer is arranged intermittently on the short lines or long lines of the sheet, and the roller is configured to abut against areas of the sheet on which the adhesive layer is arranged intermittently where the adhesive layer is not arranged. [Explanation of symbols]

[0085] 1. Wound electrode manufacturing equipment 2. Conveyor section 3a, 3b, 3c Roller 4 Winding core 5. Adhesive layer application section 6 Adhesive layer 10 Battery case 12 Exterior body 14 Sealing plate 15 Liquid injection hole 15a Sealing member 17 Gas exhaust valve 18,19 Terminal insertion holes 20 Electrode group 20a to 20c Wound electrode body 22 Positive electrode sheet 23 Positive electrode tab group 24 Negative electrode sheet 25 Negative electrode tab group 26 Separator sheet 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

Claims

1. A method for manufacturing a wound electrode assembly in which a strip-shaped positive electrode sheet and a strip-shaped negative electrode sheet are stacked with a strip-shaped separator sheet interposed therebetween and wound, the method comprising the following steps: a preparing step of preparing the positive electrode sheet, the negative electrode sheet, and the separator sheet, wherein an adhesive layer is disposed on at least one surface of at least one of the sheets; a conveying step of conveying each of the prepared sheets separately to a predetermined position where a core is disposed, wherein the sheet on which the adhesive layer is disposed is conveyed to the position of the core while a region where the adhesive layer is not disposed is brought into contact with a roller; and a winding step of winding each of the conveyed sheets around the winding core; A method for manufacturing a wound electrode body, comprising:

2. The method for manufacturing a wound electrode body according to claim 1 , wherein in the conveying step, an area of ​​the sheet on which the adhesive layer is arranged is kept substantially out of contact with the roller.

3. The method for manufacturing a wound electrode body according to claim 1 , wherein the adhesive layer is formed on at least one surface of at least one of the sheets in the preparing step.

4. The method for manufacturing a wound electrode body according to claim 1 , wherein the sheet on which the adhesive layer is disposed is the separator sheet.

5. The method for manufacturing a wound electrode assembly according to claim 4 , wherein the adhesive layer is disposed on both sides of the separator sheet.

6. the wound electrode body has a first separator sheet and a second separator sheet as the separator sheets, 3. The method for manufacturing a wound electrode body according to claim 1, wherein in the winding step, the first separator sheet, the positive electrode sheet, the second separator sheet, and the negative electrode sheet are stacked in this order and wound, or the first separator sheet, the negative electrode sheet, the second separator sheet, and the positive electrode sheet are stacked in this order and wound.

7. The rotating surface of the roller is configured in a comb shape with alternating concave and convex portions, 3. The method for manufacturing a wound electrode body according to claim 1, wherein in the conveying step, the sheet on which the adhesive layer is disposed is conveyed by bringing the convex portion into contact with an area of ​​the sheet on which the adhesive layer is disposed where the adhesive layer is not disposed.

8. In the sheet on which the adhesive layer is disposed, the adhesive layer is disposed intermittently on a short line or a long line of the sheet, 3. The method for manufacturing a wound electrode body according to claim 1, wherein in the conveying step, the roller conveys the sheet on which the adhesive layer is arranged so that the roller abuts against areas of the sheet on which the adhesive layer is intermittently arranged where the adhesive layer is not arranged.

9. A method for manufacturing an electricity storage device, comprising constructing an electricity storage device using a wound electrode body obtained by the method for manufacturing a wound electrode body according to claim 1 or 2.

10. A manufacturing apparatus for a wound electrode body in which a strip-shaped positive electrode sheet and a strip-shaped negative electrode sheet are stacked and wound with a strip-shaped separator sheet interposed therebetween, a conveying section that conveys each of the sheets separately from one another; One or more rollers configured to come into contact with an area of ​​the sheet on which an adhesive layer is disposed, where the adhesive layer is not disposed, of each of the sheets; a winding core that winds up each of the sheets that have been transported separately by the transport unit; A manufacturing apparatus for a wound electrode body, comprising:

11. 11. The manufacturing apparatus for a wound electrode body according to claim 10, wherein the roller is configured so that the area of ​​the sheet on which the adhesive layer is disposed, where the adhesive layer is disposed, does not substantially come into contact with the roller.

12. 12. The manufacturing device for a wound electrode body according to claim 10, further comprising an adhesive layer applying unit for disposing the adhesive layer on at least one surface of at least one of the sheets.

13. The rotating surface of the roller is configured in a comb shape with alternating concave and convex portions, The manufacturing device for a wound electrode body according to claim 10 or 11, wherein the protrusion is configured to abut against an area of ​​the sheet on which the adhesive layer is arranged, where the adhesive layer is not arranged.

14. In the sheet on which the adhesive layer is disposed, the adhesive layer is disposed intermittently on a short line or a long line of the sheet, 12. The manufacturing apparatus for a wound electrode body according to claim 10, wherein the roller is configured to come into contact with an area of ​​the sheet on which the adhesive layer is intermittently arranged where the adhesive layer is not arranged.

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