Power storage device and method for manufacturing the same

Abstract

To reduce damage to an electrode tab.SOLUTION: A power storage device 100 includes an electrode body 40, a case body 52, a lid 54, terminals 60, 65, an insulating member 94, current collectors 70, 75, and an insulating film 98. The electrode body 40 has tabs 42, 44. The insulating film 98 is disposed in the case body 52 so as to cover the electrode body 40. The insulating film 98 is made of a resin film that insulates the case body 52 and the electrode body 40. The insulating film 98 is joined to at least one of the lid 54, the insulating member 94 attached to the lid 54, and the current collectors 70, 75.SELECTED DRAWING: Figure 7

Description

[Technical field]

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

[0002] JP 2022-188665 A discloses a battery including an electrode body and a battery case that houses a plurality of electrode bodies. Each electrode body has a pair of flat outer surfaces. The electrode body is provided with a positive electrode and a negative electrode electrode tab group. An electrode current collector is attached to the electrode tab group. A fixing member including a base material and an adhesive layer is disposed from the pair of flat outer surfaces of the electrode body to the electrode current collector. In a battery having such a configuration, damage to the electrode tab group is said to be prevented. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2022-188665 Summary of the Invention [Problem to be solved by the invention]

[0004] The present inventors would like to propose a novel configuration for reducing damage to the electrode tabs. [Means for solving the problem]

[0005] The electricity storage device disclosed herein includes an electrode body having a tab, a case body having an opening and housing the electrode body, a lid for closing the opening, a terminal attached to the lid, an insulating member interposed between the lid and the terminal, a current collector connected to the terminal and the tab of the electrode body, and an insulating film made of a resin film arranged in the case body so as to cover the electrode body and insulates the case body and the electrode body. The insulating film is bonded to at least one of the lid, the insulating member attached to the lid, and the current collector. In such an electricity storage device, damage to the tab is reduced. [Brief description of the drawings]

[0006] [Figure 1] FIG. 1 is a perspective view showing an electricity accumulation device 100. As shown in FIG. [Diagram 2] FIG. 2 is a schematic cross-sectional view taken along line II-II in FIG. [Diagram 3] FIG. 3 is a perspective view that diagrammatically illustrates the electrode body 40. As shown in FIG. [Figure 4] FIG. 4 is a perspective view of the electrode assembly 40 to which the second current collectors 72, 77 are connected. [Diagram 5] FIG. 5 is a perspective view of the electrode assembly 40 with the lid 54 connected thereto. [Figure 6] FIG. 6 is a plan view of the insulating film 98. As shown in FIG. [Figure 7] FIG. 7 is a perspective view of the electrode body 40 covered with an insulating film 98. [Figure 8] FIG. 8 is a perspective view of the electrode body 40 covered with an insulating film 98. [Figure 9] FIG. 9 is an enlarged view of the lid 54 to which the electrode body 40 is connected. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] Hereinafter, an embodiment of the technology disclosed herein will be described with reference to the drawings. The embodiment described herein is, of course, not intended to limit the present invention in particular. Each drawing is drawn diagrammatically and does not necessarily reflect the actual product. In addition, the same reference numerals are appropriately used for members and parts that perform the same function, and duplicated descriptions are appropriately omitted. In the following description, the reference numerals L, R, F, Rr, U, and D in the drawings represent left, right, front, rear, top, and bottom, and the reference numerals X, Y, and Z in the drawings represent the short side direction, long side direction, and height direction of the power storage device, respectively. However, these are merely directions for convenience of description, and do not limit the installation form of the power storage device in any way.

[0008] <Electricity storage device 100> FIG. 1 is a perspective view showing an electricity storage device 100. FIG. 2 is a schematic cross-sectional view taken along line II-II in FIG. 1. The electricity storage device 100 includes an electrode body 40, a case body 52, a lid 54, terminals 60 and 65, current collectors 70 and 75, insulating members 90, 92 and 94, and an insulating film 98. In this specification, the term "electricity storage device" refers to a device capable of extracting electric energy. The electricity storage device includes a secondary battery that can be repeatedly charged and discharged by the movement of charge carriers between a pair of electrodes (positive and negative electrodes) via an electrolyte, and includes, for example, a lithium ion secondary battery. Hereinafter, the electricity storage device 100 will be described together with a method for manufacturing the electricity storage device 100, taking a lithium ion secondary battery as an example.

[0009] <Method of manufacturing the electricity storage device 100> A manufacturing method for the electricity storage device 100 includes the steps of preparing a case body 52, preparing an electrode body 40, preparing an insulating film 98, restraining the electrode body 40 with the insulating film 98, and housing the electrode body 40 in the case body 52.

[0010] <Step of Preparing Case Body 52> In the step of preparing the case body 52, the case body 52 that houses the electrode body 40 is prepared. In this embodiment, a square case body 52 is prepared as the case body 52. ​​As shown in FIG. 1, the case body 52 has a bottom wall 52a that is substantially rectangular in plan view, a pair of first side walls 52b that extend upward in the height direction Z from the long side of the bottom wall 52a, and a pair of second side walls 52c that extend upward in the height direction Z from the short side of the bottom wall 52a. The case body 52 has a substantially rectangular opening 52h (see FIG. 2) at the top. In other words, the case body 52 has a substantially rectangular opening at the top.

[0011] <Step of Preparing Electrode Body 40> In the step of preparing the electrode body 40, the electrode body 40 attached to the lid 54 via the current collectors 70, 75 (see FIG. 2) is prepared. In the step of preparing the electrode body 40, the electrode body 40 can be prepared as follows. The lid 54, the electrode body 40, and the current collectors 70, 75 (positive electrode current collector 70 and negative electrode current collector 75) are prepared, respectively. In this embodiment, as shown in FIG. 2, the positive electrode current collector 70 includes a positive electrode first current collector 71 and a positive electrode second current collector 72. The negative electrode current collector 75 includes a negative electrode first current collector 76 and a negative electrode second current collector 77. Hereinafter, the positive electrode first current collector 71 and the negative electrode first current collector 76 are also referred to as "first current collectors 71, 76", and the positive electrode second current collector 72 and the negative electrode second current collector 77 are also referred to as "second current collectors 72, 77". A positive electrode first current collector 71 and a negative electrode first current collector 76 are attached to the lid 54. A positive electrode second current collector 72 and a negative electrode second current collector 77 are attached to the electrode body 40. Below, the lid 54, the electrode body 40, and the current collectors 70, 75 will be described in order. Note that the current collectors 70, 75 do not need to be separated into the first current collectors 71, 76 and the second current collectors 72, 77, and may each be integrated into a single current collector.

[0012] <Lid 54> The lid 54 is a member that closes the opening 52h at the top of the case body 52. ​​The case body 52 and the lid 54 are collectively referred to as the case 50 as appropriate. The lid 54 has a shape corresponding to the opening 52h. In this embodiment, the lid 54 is a substantially rectangular plate-like member. The lid 54 is provided with a liquid injection hole 55 and a gas exhaust valve 57. The liquid injection hole 55 is a through hole provided for injecting an electrolyte (not shown) into the inside of the case 50. When the injection of the electrolyte is completed, the liquid injection hole 55 is sealed by a sealing member 56. The gas exhaust valve 57 is a thin-walled portion designed to break (open) when a large amount of gas is generated in the case 50 and to exhaust the gas. The lid 54 is formed with terminal insertion holes 58 and 59 (see FIG. 2) to which the positive electrode terminal 60 and the negative electrode terminal 65 are attached, respectively. The terminal insertion holes 58 and 59 are each formed at an end of the lid 54 in the width direction Y.

[0013] Terminals (a positive electrode terminal 60 and a negative electrode terminal 65) are attached to the lid 54 via insulating members 90, 92, and 94. The positive electrode terminal 60 and the negative electrode terminal 65 are attached to the ends of the lid 54 in the width direction Y of the electricity storage device 100. The positive electrode terminal 60 is connected to a plate-shaped positive electrode external conductive member 62 on the outside of the case 50. The negative electrode terminal 65 is connected to a plate-shaped negative electrode external conductive member 67 on the outside of the case 50. The positive electrode external conductive member 62 and the negative electrode external conductive member 67 are connected to other electricity storage devices and external devices via external connection members (such as bus bars).

[0014] <First current collector 71, 76> The first current collectors 71, 76 are plate-shaped conductive members. As shown in Fig. 2, the positive electrode first current collector 71 and the negative electrode first current collector 76 each extend along the inner surface of the lid 54. The positive electrode first current collector 71 and the negative electrode first current collector 76 are attached to the inner surface of the lid 54. The lower end 60c of the positive electrode terminal 60 is connected to the positive electrode first current collector 71. The lower end 65c of the negative electrode terminal 65 is connected to the negative electrode first current collector 76.

[0015] <Insulating members 90, 92, 94> The insulating members 90, 92, 94 include a gasket 90, an external insulating member 92, and an internal insulating member 94. The gasket 90 is attached to the terminal insertion holes 58, 59 of the battery 54. The gasket 90 is interposed between the lid 54 and the terminals 60, 65 in the terminal insertion holes 58, 59, and prevents electrical conduction between the lid 54 and the terminals 60, 65. The external insulating member 92 is disposed on the outer surface of the lid 54. The external insulating member 92 is interposed between the lid 54 and the positive electrode external conductive member 62 and the negative electrode external conductive member 67 on the outer surface of the lid 54, and prevents electrical conduction between the lid 54 and the positive electrode external conductive member 62 and the negative electrode external conductive member 67. The internal insulating member 94 is disposed on the inner surface of the lid 54. The internal insulating member 94 is interposed between the lid 54 and the first current collectors 71, 76 on the inner surface of the lid 54, and prevents electrical conduction between the lid 54 and the first current collectors 71, 76.

[0016] The internal insulating member 94 has a plate-shaped base portion 94a attached to the inner surface of the lid 54. The internal insulating member 94 has a protruding portion 94b protruding from the base portion 94a toward the electrode body 40. The protruding portion 94b restricts the upward and downward movement of the electrode body 40 and prevents the electrode body 40 and the lid 54 from directly contacting each other. The material of the insulating member has a predetermined insulating property and is selected in consideration of the electrolyte resistance and heat resistance. As the insulating member, a synthetic resin material such as a polyolefin resin, a polyamide resin, a PPS resin, or a fluorine resin can be used.

[0017] <Electrode body 40> FIG. 3 is a perspective view that shows a schematic view of the electrode body 40. As shown in FIG. 3, the electrode body 40 is an electrode body in which a strip-shaped positive electrode 10 and a strip-shaped negative electrode 20 are wound with a strip-shaped separator 30 interposed therebetween. The electrode body 40 has tabs (a positive electrode tab group 42 and a negative electrode tab group 44 in this embodiment). The electrode body 40 is a so-called wound electrode body. The electrode body 40 is prepared, for example, by stacking the positive electrode 10 and the negative electrode 20 with the separator 30 interposed therebetween in the same direction and winding them around a winding axis WL. The outer peripheral surface of the electrode body 40 after winding is covered with the separator 30. The winding axis WL is set in the width direction of the positive electrode 10, the negative electrode 20, and the separator 30. In this embodiment, the electrode body 40 is press-molded after winding to be formed into a flat shape. The electrode body 40 has a flat portion 40f (see FIG. 4) with a flat outer surface. However, the electrode assembly 40 is not limited to this form. The electrode assembly 40 may be a so-called laminated electrode assembly in which rectangular positive and negative electrodes are stacked with a separator interposed therebetween.

[0018] <Positive electrode 10> The positive electrode 10 is a long strip-shaped member. The positive electrode 10 includes a positive electrode core 12, which is a foil-shaped metal member, and a positive electrode active material layer 14 formed on the surface of the positive electrode core 12. From the viewpoint of battery performance, the positive electrode active material layer 14 is preferably formed on both sides of the positive electrode core 12. A positive electrode tab 12t protruding toward the outside in the Y direction (the left side in FIG. 3) is provided on one side edge of the positive electrode 10. A plurality of positive electrode tabs 12t are provided at predetermined intervals in the longitudinal direction of the positive electrode 10. The positive electrode tabs 12t are regions where the positive electrode active material layer 14 and the protective layer 16 are not formed, and the positive electrode core 12 is exposed. In a state where the electrode body 40 is wound, the positive electrode tabs 12t are stacked and connected to each other to form a positive electrode tab group 42. A metal material having a predetermined conductivity is preferably used as the positive electrode core 12. The positive electrode core 12 is preferably made of, for example, aluminum or an aluminum alloy.

[0019] The positive electrode active material layer 14 is a layer containing a positive electrode active material. The positive electrode active material is a material that can reversibly absorb and release charge carriers in relation to the negative electrode active material described later. The positive electrode active material is not particularly limited. For example, a lithium transition metal composite oxide is preferably used as the positive electrode active material.

[0020] The positive electrode active material layer 14 may contain additives other than the positive electrode active material. The positive electrode active material layer 14 may contain a binder. As the binder, a resin binder may be preferably used. As the resin binder, for example, polyvinylidene fluoride (PVDF) or the like may be preferably used. The positive electrode active material layer 14 preferably contains a conductive material. As the conductive material, a carbon material such as acetylene black (AB) may be preferably used.

[0021] A protective layer 16 may be provided on one side edge of the positive electrode 10 as necessary. The protective layer 16 is a layer configured to have lower electrical conductivity than the positive electrode active material layer 14. The protective layer 16 is provided on the positive electrode core 12 at a position facing the negative electrode active material layer 24 via the separator 30. The configuration of the protective layer 16 is not particularly limited, and may be, for example, a layer coated with a resin or a layer containing inorganic particles or a binder.

[0022] <Negative electrode 20> The negative electrode 20 is a long strip-shaped member. The negative electrode 20 includes a negative electrode core 22, which is a foil-shaped metal member, and a negative electrode active material layer 24 formed on the surface of the negative electrode core 22. From the viewpoint of battery performance, the negative electrode active material layer 24 is preferably formed on both sides of the negative electrode core 22. A negative electrode tab 22t protruding toward the outside in the Y direction (the right side in FIG. 3) is provided on one side edge of the negative electrode 20. The negative electrode tab 22t protrudes toward the opposite side to the above-mentioned positive electrode tab 12t. A plurality of negative electrode tabs 22t are provided at predetermined intervals in the longitudinal direction of the negative electrode 20. The negative electrode tabs 22t are regions where the negative electrode active material layer 24 is not formed and the negative electrode core 22 is exposed. In a state where the electrode body 40 is wound, the negative electrode tabs 22t are stacked and connected to each other to form a negative electrode tab group 44. A metal material having a predetermined electrical conductivity is preferably used as the negative electrode core 22. The negative electrode core 22 is preferably made of, for example, copper or a copper alloy.

[0023] The negative electrode active material layer 24 is a layer containing a negative electrode active material. The negative electrode active material is a material that can reversibly absorb and release charge carriers in relation to the positive electrode active material. The negative electrode active material is not particularly limited. For example, a carbon material, a silicon-based material, and a mixed oxide thereof are preferably used as the negative electrode active material. For example, graphite, hard carbon, soft carbon, amorphous carbon, etc. can be used as the carbon material. For example, silicon, silicon oxide (silica), etc. can be used as the silicon-based material.

[0024] The negative electrode active material layer 24 may contain an additive other than the negative electrode active material. The negative electrode active material layer 24 may contain a binder as an additive. As the binder, a resin binder is preferably used. As the resin binder, for example, styrene butadiene rubber (SBR), carboxymethyl cellulose (CMC), polyacrylic acid (PAA), etc. may be contained. The negative electrode active material layer 24 preferably contains a conductive material. As the conductive material, a carbon material such as acetylene black (AB) or carbon nanotubes can be preferably used.

[0025] <Separator 30> The separator 30 is a long strip-shaped member that prevents contact between the positive electrode 10 and the negative electrode 20 and allows charge carriers to pass through. The width of the separator 30 can be set to a dimension that can cover the positive electrode active material layer 14 of the positive electrode 10 and the negative electrode active material layer 24 of the negative electrode 20. As the separator 30, a resin porous film having a plurality of fine holes through which charge carriers can pass is preferably used. As the separator 30, for example, a porous sheet (film) made of a resin such as a polyolefin such as polyethylene (PE) or polypropylene (PP) or a polyamide can be mentioned. Such a porous sheet may have a single layer structure or a laminate structure of two or more layers.

[0026] A heat-resistant layer may be formed on the resin sheet constituting the separator 30. The heat-resistant layer is a layer having excellent heat resistance. The heat-resistant layer preferably contains ceramic particles and a binder. As the ceramic particles, for example, alumina or the like can be used.

[0027] The separator 30 may include an adhesive layer. The adhesive layer is a layer that has excellent adhesiveness to the electrode plate (positive electrode 10, negative electrode 20). The adhesive layer may be formed on the surface of a resin sheet that constitutes the separator 30. The adhesive layer bonds the positive electrode 10 and the separator 30, and facilitates bonding between the negative electrode 20 and the separator 30. A known material may be used for the adhesive layer. A resin material may be used for the adhesive layer. The adhesive layer may include a binder such as polyvinylidene fluoride. The adhesive layer may include ceramic particles. For example, an adhesive layer that generates adhesive force by pressure, heat, or the like may be used.

[0028] Fig. 4 is a perspective view of the electrode assembly 40 to which the second current collectors 72, 77 are connected. Fig. 5 is a perspective view of the electrode assembly 40 to which the lid 54 is connected.

[0029] <Second current collector 72, 77> The second current collectors 72, 77 are plate-shaped conductive members. As shown in Fig. 4, the positive electrode second current collector 72 and the negative electrode second current collector 77 are connected to tabs (positive electrode tab group 42 and negative electrode tab group 44) of the electrode assembly 40, respectively. In other words, the electrode assembly 40 is connected to the current collectors (positive electrode second current collector 72 and negative electrode second current collector 77) via tabs. The tabs and the second current collectors 72, 77 can be joined by, for example, laser welding.

[0030] As shown in FIG. 5, the positive electrode tab group 42 and the negative electrode tab group 44 are folded with the second current collectors 72, 77 connected to them, respectively. The folded second current collectors 72, 77 are connected to the first current collectors 71, 76 arranged on the inner surface of the lid 54. In this way, the electrode body 40 is attached to the lid 54. In this embodiment, three electrode bodies 40 are attached to the lid 54. The electrode bodies 40 are stacked along the thickness direction X and attached to the lid 54 in a state where they are aligned in the width direction Y and the height direction Z. The number of electrode bodies 40 attached to the lid 54 is not particularly limited, and may be one or more.

[0031] <Process of preparing insulating film 98> In the step of preparing the insulating film 98, an insulating film 98 (see FIGS. 1 and 6) made of a resin film is prepared. The insulating film 98 is a film-like insulating member that is placed inside the case body 52 so as to cover the electrode body 40. For example, a resin material such as polypropylene (PP) or polyethylene (PE) can be used as the insulating film 98. Here, the insulating film 98 can be prepared according to the shape of the electrode body 40.

[0032] Fig. 6 is a plan view of the insulating film 98. Fig. 6 shows a developed view of the insulating film 98 before covering the electrode body 40. As shown in Fig. 6, the insulating film 98 has a bottom surface portion 98a, a wide surface portion 98b, and a side surface portion 98c. The dimensions of the bottom surface portion 98a, the wide surface portion 98b, and the side surface portion 98c can be set according to the dimensions of the electrode body 40.

[0033] The bottom surface portion 98a is substantially rectangular. The bottom surface portion 98a has dimensions corresponding to the thickness (dimension in the X direction in FIG. 5) and width (dimension in the Y direction in FIG. 5) of the electrode body 40. In this embodiment, the dimension of the short side of the bottom surface portion 98a is set to be substantially the same as the thickness of the electrode body 40. The dimension of the bottom surface portion 98a may be set so that the difference between the dimension of the short side of the bottom surface portion 98a and the thickness of the electrode body 40 is 1 mm or less (for example, 0.5 mm or less). In this specification, the "thickness of the electrode body 40" refers to the total thickness of the electrode body 40. When a plurality of electrode bodies 40 are stacked in the thickness direction, the "thickness of the electrode body 40" refers to the total thickness of the plurality of electrode bodies 40. In this embodiment, the "thickness of the electrode body 40" refers to the total thickness of the three stacked electrode bodies 40.

[0034] Moreover, the dimension of the long side of the bottom portion 98a is set to be approximately the same as the width of the electrode body 40 including the attached current collectors 70, 75. In this embodiment, the width of the electrode body 40 corresponds to the dimension from the outer surface of the second current collector 72 to the outer surface of the second current collector 77. The dimension of the bottom portion 98a may be set so that the difference between the dimension of the long side of the bottom portion 98a and the width of the electrode body 40 is 1 mm or less (0.5 mm or less).

[0035] The wide surface portion 98b includes a first wide surface portion 98b1 and a second wide surface portion 98b2. The first wide surface portion 98b1 and the second wide surface portion 98b2 are each substantially rectangular. The first wide surface portion 98b1 and the second wide surface portion 98b2 each have dimensions corresponding to the width and height (dimension in the Z direction in FIG. 5) of the electrode body 40. The first wide surface portion 98b1 and the second wide surface portion 98b2 extend from a side of the bottom surface portion 98a that corresponds to the width (dimension in the Y direction in FIG. 5) of the electrode body 40.

[0036] The side surface portion 98c is provided as a pair in the left-right direction Y. The pair of side surface portions 98c extend from the bottom surface portion 98a and the wide surface portion 98b, respectively. The pair of side surface portions 98c each include a first side surface portion 98c1, a second side surface portion 98c2, and a third side surface portion 98c3. The first side surface portion 98c1 extends from the first wide surface portion 98b1. The second side surface portion 98c2 extends from the second wide surface portion 98b2. The third side surface portion 98c3 extends from the bottom surface portion 98a. In this embodiment, the first side surface portion 98c1, the second side surface portion 98c2, and the third side surface portion 98c3 are symmetrical in the left-right direction Y except for a cut-off portion 98d1, which will be described later.

[0037] A notch 98d is formed between the first side surface portion 98c1 and the third side surface portion 98c3, and between the second side surface portion 98c2 and the third side surface portion 98c3. In this embodiment, the notch 98d is formed from the end of the side surface portion 98c in the left-right direction Y to the boundary between the side surface portion 98c and the bottom surface portion 98a and the wide surface portion 98b. The notch 98d is in the shape of a substantially right-angled triangle. The side surface portion 98c may be provided with a portion 98d1 that is partially cut away to indicate the direction of the insulating film 98.

[0038] The shape of the cutout 98d is not particularly limited, and may be, for example, a substantially rectangular shape or a shape formed of a curve such as an arc. Alternatively, the insulating film 98 may not have the cutout 98d, and a slit may be formed in the side surface portion 98c along an extension line of the boundary between the bottom surface portion 98a and the wide surface portion 98b.

[0039] The side surface portion 98c has a joint portion 98e that is to be joined to the current collectors 70, 75 in a later process. In this embodiment, the joint portion 98e is set on the first side surface portion 98c1 and the second side surface portion 98c2. The joint portion 98e is set at a position where the first side surface portion 98c1 and the second side surface portion 98c2 overlap when the insulating film 98 is assembled. In this embodiment, the joint portion 98e is set at a position where the joint portion 98e contacts the current collector 70 attached to the middle electrode body 40 among the three electrode bodies 40. The joint portion 98e may be subjected to a treatment for improving the bonding property when it is joined to the current collectors 70, 75 in a later process. The position of the joint portion 98e is not particularly limited.

[0040] The insulating film 98 has boundaries B1 to B4 between the bottom surface portion 98a, the wide surface portion 98b, and the side surface portion 98c. The insulating film 98 is folded along the boundaries B1 to B4 in a later process to cover the electrode body 40. The boundaries B1 to B4 are set according to the dimensions (e.g., thickness, width, height) of the electrode body 40. The boundary B1 is set between the bottom surface portion 98a and the wide surface portion 98b. The boundary B2 is set between the first wide surface portion 98b1 and the first side surface portion 98c1. The boundary B3 is set between the second wide surface portion 98b2 and the second side surface portion 98c2. The boundary B4 is set between the bottom surface portion 98a and the third side surface portion 98c3.

[0041] As described above, the dimensions of the long side and the short side of the bottom surface portion 98a are set to be approximately the same as the thickness and width of the electrode body 40, respectively. From the viewpoint of dimensional error of parts, the dimensions of the long side and the short side of the bottom surface portion 98a can be set to have a dimensional difference of 1 mm or less (e.g., 0.5 mm or less) from the thickness and width of the electrode body 40, respectively. The boundaries B1 to B4 are provided at positions on the side circumferential surface of the electrode body 40 where the electrode body 40 and the insulating film 98 are likely to be restrained when the electrode body 40 is covered with the insulating film 98.

[0042] The insulating film 98 may be subjected to a treatment to improve workability when folding the film 98. Examples of such treatment include preliminarily folding the film 98 along the boundaries B1 to B4, or forming grooves along the boundaries B1 to B4 that are not large enough to tear the film 98.

[0043] <Step of Restraining Electrode Body 40 with Insulating Film 98> In the step of restraining the electrode body 40 with the insulating film 98 (hereinafter also simply referred to as the "restraining step"), the electrode body 40 is covered and restrained with the insulating film 98. The step of restraining the electrode body 40 with the insulating film 98 also includes joining the insulating film 98 to at least one of the lid 54, the insulating member 94 attached to the lid 54, and the current collectors 70, 75. In this embodiment, in the restraining step, a portion of the insulating film 98 and a portion of the current collector 70 are joined.

[0044] Fig. 7 is a perspective view of the electrode body 40 covered with an insulating film 98. Fig. 7 shows a state in which a part of the insulating film 98 has been broken to expose the electrode body 40. As shown in Fig. 7, in the restraining step, the insulating film 98 is folded along the electrode body 40 to cover the electrode body 40 with the insulating film. The insulating film 98 is folded along the boundaries B1 to B4.

[0045] First, the bottom surface portion 98a of the insulating film 98 and the lower surface of the electrode body 40 are aligned. The insulating film 98 is folded along the boundary B1. As a result, the wide surface portion 98b of the insulating film 98 faces the flat portion 40f of the electrode body 40. The insulating film 98 is folded along the boundary B2. As a result, the first side surface portion 98c1 of the insulating film 98 faces the side surface of the electrode body 40 and the second current collectors 72, 77 (see FIG. 5). The insulating film 98 is folded along the boundary B3. As a result, the second side surface portion 98c2 of the insulating film 98 is overlapped from the outside against a part of the first side surface portion 98c1. The insulating film 98 is folded along the boundary B4. As a result, the third side surface portion 98c3 of the insulating film 98 is overlapped from the outside against the first side surface portion 98c1 and a part of the second side surface portion 98c2. As a result, the electrode body 40 is covered with the insulating film 98. At this time, the folding position of the insulating film 98 may be appropriately adjusted in order to firmly restrain the electrode body 40. The folding order of the insulating film 98 is not particularly limited, and for example, the first wide surface portion 98b1 of the insulating film 98 and the flat portion 40f of the electrode body 40 may be aligned first, or the third side surface portion 98c3 of the insulating film 98 may be positioned inside the first side surface portion 98c1 and a part of the second side surface portion 98c2.

[0046] Next, with the electrode body 40 covered with the insulating film 98, a portion of the insulating film 98 is bonded to the current collectors 70, 75. At this time, it is preferable to bond a portion of the insulating film 98 to the current collectors 70, 75 while applying a restraining pressure to the electrode body 40 with the insulating film 98. The bonding method is not particularly limited.

[0047] In this embodiment, a part of the insulating film 98 is heated to weld a part of the insulating film 98 and a part of the current collectors 70 and 75. As shown in FIG. 7, a joint 98e is set at a portion where a first side portion 98c1 and a second side portion 98c2 of the insulating film 98 overlap. The joint 98e of the insulating film 98 is heated. The heating method is not particularly limited. For example, the insulating film 98 may be welded to the current collectors 70 and 75 by pressing a welding pin heated to a melting point or higher of the insulating film 98 against the joint 98e. The heating conditions at this time are set to such an extent that the insulating film 98 melts at the joint 98e against which the heated welding pin is pressed, and is welded to the current collectors 70 and 75. The heating conditions are set appropriately according to the area of ​​the joint 98e, the materials of the insulating film 98 and the current collectors 70 and 75, and the like. The heating conditions may include the diameter of the welding pin, the pressure at which the welding pin is pressed, the temperature, and the heating time.

[0048] <Step of housing the electrode body 40 in the case body 52> In the step of housing the electrode body 40 in the case body 52 (hereinafter also simply referred to as the "housing step"), the electrode body 40 covered with the insulating film 98 is housed in the case body 52 (see FIG. 2). In the housing step, as shown in FIG. 2, the electrode body 40 covered with the insulating film 98 and restrained is placed in the case body 52 by a known method. After housing the electrode body 40, the opening 52h is closed by welding the lid 54 to which the electrode body 40 is attached and the case body 52. ​​An electrolyte is injected from the liquid injection hole 55 to construct an electricity storage device assembly. The electricity storage device assembly is subjected to an initial charging process and an aging process by a known method, and an electricity storage device 100 can be manufactured.

[0049] However, when vibration is applied to the electricity storage device, the electrode body may move within the case. The electrode body is connected to the current collector and the terminal via a tab. The tab extends from the core body and is connected to the current collector in a stacked state. When the electrode body moves within the case, the current collector attached to the lid of the case and the electrode body move relatively. This may damage the tab. According to the knowledge of the present inventor, when the electrode body is covered with an insulating film during the manufacture of a conventional electricity storage device, there is no idea of ​​restraint, and the process is simply positioned as an assembly process of an insulating member, so that the assembled insulating film is set to a size with a margin relative to the electrode body. In addition, when the electrode body is fixed using a fixing member (for example, a tape having a base material and an adhesive layer), an additional process is required, the number of parts increases, and other reasons may increase the manufacturing cost.

[0050] The electricity storage device 100 manufactured in the above-described embodiment includes the electrode body 40, the case body 52, the lid 54, the terminals 60, 65, the insulating member 94, the current collectors 70, 75, and the insulating film 98. The electrode body 40 has the tabs 42, 44. The case body 52 has an opening 52h. The case body 52 houses the electrode body 40. The lid 54 is a member that closes the opening 52h. The terminals 60, 65 are attached to the lid 54. An insulating member 94 is interposed between the lid 54 and the terminals 60, 65. The current collectors 70, 75 are connected to the terminals 60, 65 and the tabs 42, 44 of the electrode body 40. The insulating film 98 is disposed in the case body 52 so as to cover the electrode body 40. The insulating film 98 is made of a resin film that insulates the case body 52 and the electrode body 40. An insulating film 98 is bonded to the current collectors 70 and 75 .

[0051] In this electricity storage device 100, the electrode body 40 is covered with the insulating film 98, and the insulating film 98 and the current collectors 70, 75 are joined together. The electrode body 40 is covered with the insulating film 98 in a state where a restraining pressure is applied, and the insulating film 98 and the current collectors 70, 75 are connected together. This configuration prevents the electrode body 40 from moving relative to the current collectors 70, 75. This makes it difficult for a load to be applied to the tabs 42, 44, and prevents damage to the tabs 42, 44.

[0052] Furthermore, the insulating film 98 is joined to the current collectors 70, 75, and the electrode body 40 is restrained without using any additional members such as fixing members. Therefore, a configuration for restraining the electrode body 40 can be provided without increasing the number of parts, reducing manufacturing costs and energy required for manufacturing.

[0053] In the electricity storage device 100, a portion of the current collectors 70, 75 is welded to the insulating film 98. Here, the relative movement between the electrode body 40 and the current collectors 70, 75 is suppressed without using an additional fixing member, and damage to the tabs 42, 44 is suppressed. This reduces the number of parts. In addition, the welding of the current collectors 70, 75 and the insulating film 98 can be performed simultaneously when the electrode body 40 is covered with the insulating film 98 and the first side surface portion 98c1 and the second side surface portion 98c2 are welded. Therefore, the electrode body 40 can be restrained without providing a new process of fixing the electrode body 40 with a fixing member or the like. This reduces manufacturing costs and can reduce the energy required for manufacturing.

[0054] In the above-described embodiment, the dimensions of the insulating film 98 are set at the boundaries B1 to B4 so that when the electrode body 40 is covered with the insulating film 98, the gap between the electrode body 40 and the insulating film 98 on the side peripheral surface of the electrode body 40 is minimized. This makes it easier for the electrode body 40 to be restrained by the insulating film 98. As a result, damage to the tabs 42, 44 during the manufacture of the electricity storage device 100 is suppressed.

[0055] The position and joining method of the joint 98e are not limited to those in the above embodiment. For example, the position and range of the joint 98e can be appropriately set from the viewpoint of preventing damage to the tabs 42 and 44 and from the viewpoint of productivity.

[0056] FIG. 8 is a perspective view of the electrode body 40 covered with an insulating film 98. In FIG. 8, the side of the electrode body 40 covered with the insulating film 98 is enlarged. In FIG. 8, the configuration inside the insulating film 98 is indicated by a broken line. Here, the position of the joint 98e will be described using the positive electrode second current collector 72 as an example, but a similar configuration can be used on the negative electrode side, so detailed description will be omitted. As shown in FIG. 8, the second current collector 72 includes a lower portion 72a connected to the tab 42 and an upper portion 72b connected to the first current collector 71. The lower portion 72a and the upper portion 72b extend along the vertical direction. A step is provided between the lower portion 72a and the upper portion 72b, and the lower portion 72a is located outside the upper portion 72b. The shape of the second current collector 72 is not limited to this form. The second current collector 72 may be, for example, a flat plate shape without a step.

[0057] The joint 98e can be provided at a position in contact with the outermost portion of the current collector 70 (the lower portion 72a in this embodiment). This allows the electrode body 40 to be firmly restrained by the insulating film 98. The joint 98e may also be provided in a region R where a corresponding position on the opposite side is connected to the tab 42. This can reduce the load applied to the joint 98e during joining.

[0058] The joint 98e is preferably set in as wide an area as possible of the lower portion 72a. However, from the viewpoint of productivity, the position of the joint 98e may be set in a part of the position where it contacts the lower portion 72a. From the viewpoint of the pressure during joining and the viewpoint of widening the joining range, a welding pin capable of welding at multiple points may be used.

[0059] From the viewpoint of preventing poor bonding due to misalignment, the position of the joint 98e may be set to a part of the position where it contacts the lower part 72a. Furthermore, when multiple electrode bodies 40 are covered with the insulating film 98, the joint 98e can be set to a position where it contacts the current collector 70 connected to the electrode body 40 arranged in the center. This allows the electrode body 40 to be stably restrained.

[0060] In the above-described embodiment, the current collectors 70, 75 and the insulating film 98 are bonded by fusing the insulating film 98 to the current collectors 70, 75 by heating. However, the bonding between the insulating film 98 and the current collectors 70, 75 is not limited to this form. A part of the current collectors 70, 75 may be bonded to a part of the insulating film 98 (the joint 98e in this embodiment) via an adhesive layer. For example, in the step of preparing the electrode body 40, an adhesive layer may be formed on a part of the current collectors 70, 75. When the joint 98e is provided at a position where the first side portion 98c1 and the second side portion 98c2 of the insulating film 98 overlap, the adhesive layer may also be formed on the joint 98e of the insulating film 98. Although not particularly limited, for example, a rubber-based adhesive may be used as the adhesive layer. In the restraining step, the part where the adhesive layer is formed and a part of the insulating film 98 (the joint 98e in this embodiment) may be bonded.

[0061] By using an adhesive layer, it is easy to form the adhesive layer over a wide area on the objects to be joined (current collectors 70, 75 in this embodiment). Therefore, it is easy to join the current collectors 70, 75 and the insulating film 98 over a wide area without reducing productivity. By joining the current collectors 70, 75 and the insulating film 98 over a wide area, the electrode body 40 can be more firmly restrained. The adhesive layer may also be formed on the flat portion 40f of the electrode body 40. This allows a wide surface of the electrode body 40 to be joined to the insulating film 98. This allows the electrode body 40 to be more firmly restrained.

[0062] The portion where the insulating film 98 and the current collectors 70, 75 are joined may be subjected to a surface treatment to improve the joining property. For example, in the step of preparing the electrode body 40, the portion of the current collectors 70, 75 where the insulating film 98 is joined may be subjected to a surface treatment. In the restraining step, the current collectors 70, 75 and the insulating film 98 may be joined at the portion where the surface treatment has been applied. As the surface treatment, a treatment that increases the surface roughness of the current collectors 70, 75 may be adopted. Examples of the surface treatment include laser marker, shot blasting, etching, etc. From the viewpoint of productivity and influence on parts other than the joint, it is preferable that the surface treatment is limited to the joint. From the viewpoint of limiting the processing capacity of the surface treatment and the range of the surface treatment, it is preferable to treat the surfaces of the current collectors 70, 75 with a laser marker that is easy to locally surface treat the target object.

[0063] The above describes joining the insulating film 98 to the current collectors 70, 75 and restraining the electrode body 40. However, as long as the electrode body 40 is restrained and damage to the tabs 42, 44 is suppressed, the members to which the insulating film 98 is joined are not limited to the current collectors 70, 75. The insulating film 98 may be joined to, for example, the lid 54, the insulating member 94, etc.

[0064] FIG. 9 is an enlarged view of the lid 54 to which the electrode body 40 is connected. In FIG. 9, the side of the electrode body 40 and the lid 54 are shown as viewed along the thickness direction (X direction) of the electrode body 40. In FIG. 9, the position where the insulating film 98 can be arranged is shown by a two-dot chain line. As shown in FIG. 9, the lid 54 protrudes from the second current collector 72 in the width direction Y. The insulating film 98 may be attached to the protruding portion. For example, the upper portion of the insulating film 98 is folded while the insulating film 98 is aligned with the current collector 70 (in this embodiment, the lower portion 72a of the second current collector 72). The folded portion of the insulating film 98 can be bonded to the bottom surface 54a of the lid 54. This positions the insulating film 98, making it difficult for the electrode body 40 to move in the width direction Y. The insulating film 98 may also be bonded to the side surface 94a1 of the base portion 94a of the insulating member 94. At this time, it is preferable that the insulating film 98 contacts the flat portion 40f of the electrode body 40. This makes it easier to restrict movement along the thickness direction of the electrode body 40. As a result, the electrode body 40 is firmly restrained, and damage to the tab 42 can be suppressed.

[0065] The technology disclosed herein has been described above in various ways. Unless otherwise specified, the embodiments and the like described herein do not limit the present invention. Furthermore, the technology disclosed herein can be modified in various ways, and each component and each process described herein can be omitted or combined as appropriate unless a particular problem occurs. Furthermore, this specification includes the disclosures described in the following sections.

[0066] Section 1: an electrode body having a tab; A case body having an opening and housing the electrode body; A cover that covers the opening; A terminal attached to the lid; an insulating member interposed between the lid and the terminal; a current collector connected to the terminal and the tab of the electrode assembly; an insulating film made of a resin film that is disposed in the case body so as to cover the electrode body and insulates the case body from the electrode body; Equipped with The insulating film is bonded to at least one of the lid, the insulating member attached to the lid, and the current collector. Energy storage device.

[0067] Section 2: Item 2. The electricity storage device according to item 1, wherein the insulating film is bonded to the current collector.

[0068] Section 3: Item 3. The electricity storage device according to item 2, wherein a portion of the current collector is welded to a portion of the insulating film.

[0069] Section 4: Item 3. The electricity storage device according to item 2, wherein a portion of the current collector is joined to a portion of the insulating film via an adhesive layer.

[0070] Section 5: 5. The electricity storage device according to any one of items 2 to 4, wherein a portion of the current collector that is bonded to the insulating film is subjected to a surface treatment.

[0071] Item 6: preparing a case body having an opening and housing the electrode assembly; providing the electrode assembly attached to a lid via a current collector; preparing an insulating film made of a resin film; restraining the electrode body with the insulating film; a step of housing the electrode body covered with the insulating film in the case body; Including, the electrode body prepared in the step of preparing an electrode body is connected to a current collector via a tab, and a terminal is attached to the lid via an insulating member; the restraining step includes bonding the insulating film to at least one of the lid, an insulating member attached to the lid, and the current collector; A method for manufacturing an electricity storage device.

[0072] Section 7: 7. The method for producing an electricity storage device according to item 6, wherein in the restraining step, a part of the insulating film and a part of the current collector are joined together.

[0073] Section 8: 8. The method for producing an electricity storage device according to item 7, wherein in the restraining step, a part of the insulating film is heated to weld the part of the insulating film and at least a part of the current collector.

[0074] Section 9: In the step of preparing the electrode body, an adhesive layer is formed on a part of the current collector, 8. The method for producing an electricity storage device according to item 7, wherein in the restraining step, a portion of the current collector where the adhesive layer is formed is joined to a part of the insulating film.

[0075] Section 10: In the step of preparing the electrode body, a surface treatment is performed on a portion of the current collector to be joined to the insulating film, 10. The method for producing an electricity storage device according to any one of items 7 to 9, wherein in the restraining step, the current collector and the insulating film are joined at a site where the surface treatment has been performed. [Explanation of symbols]

[0076] 10 positive electrode 12 Positive electrode core 12t Positive tab 14 Cathode active material layer 16 Protective layer 20 negative electrode 22 Negative electrode core 22t negative electrode tab 24 Negative electrode active material layer 30 Separator 40 Electrode body 40f flat area 42 Positive electrode tab group (tab) 44 Negative electrode tab group (tab) 50 cases 52 Case body 52h opening 54 Lid 54a Bottom 58,59 Terminal insertion hole 60 Positive terminal (terminal) 60c,65c bottom end 62 Positive electrode external conductive member 65 Negative terminal (terminal) 67 Negative electrode external conductive member 70 Positive electrode collector (current collector) 71 Positive electrode first current collector 72 Positive electrode second current collector 72a Lower 72b upper part 75 Negative electrode current collector (current collector) 76 Negative electrode first current collector 77 Negative electrode second current collector 94 Internal insulating material (insulating material) 94a Base 94a1 Side 94b Protrusion 98 Insulating Film 98a Bottom part 98b Wide surface section 98c side part 98d Cutout 98e Joint 100 Energy storage device B1~B4 boundary R region WL Winding shaft

Claims

1. an electrode body having a tab; A case body having an opening and housing the electrode body; A cover that covers the opening; A terminal attached to the lid; an insulating member interposed between the lid and the terminal; a current collector connected to the terminal and the tab of the electrode assembly; an insulating film made of a resin film that is disposed in the case body so as to cover the electrode body and insulates the case body from the electrode body; Equipped with the insulating film is bonded to at least one of the lid, the insulating member attached to the lid, and the current collector; Energy storage device.

2. The electricity storage device according to claim 1 , wherein the insulating film is bonded to the current collector.

3. The electricity storage device according to claim 2 , wherein a portion of the current collector is welded to a portion of the insulating film.

4. The electricity storage device according to claim 2 , wherein a portion of the current collector is joined to a portion of the insulating film via an adhesive layer.

5. The electricity storage device according to any one of claims 2 to 4, wherein a surface treatment is applied to a portion of the current collector that is bonded to the insulating film.

6. preparing a case body having an opening and housing the electrode assembly; providing the electrode assembly attached to a lid via a current collector; preparing an insulating film made of a resin film; restraining the electrode body with the insulating film; a step of housing the electrode body covered with the insulating film in the case body; Including, the electrode body prepared in the step of preparing an electrode body is connected to a current collector via a tab, and a terminal is attached to the lid via an insulating member; the restraining step includes joining the insulating film to at least one of the lid, an insulating member attached to the lid, and the current collector. A method for manufacturing an electricity storage device.

7. The method for producing an electricity storage device according to claim 6 , wherein in the restraining step, a part of the insulating film and a part of the current collector are joined together.

8. The method for producing an electricity storage device according to claim 7 , wherein in the restraining step, a part of the insulating film is heated to weld the part of the insulating film and at least a part of the current collector.

9. In the step of preparing the electrode body, an adhesive layer is formed on a part of the current collector, The method for producing an electricity storage device according to claim 7 , wherein in the restraining step, a portion of the current collector where the adhesive layer is formed is joined to a part of the insulating film.

10. In the step of preparing the electrode body, a surface treatment is performed on a portion of the current collector to be joined to the insulating film, The method for producing an electricity storage device according to claim 7 , wherein in the restraining step, the current collector and the insulating film are joined at a portion where the surface treatment has been performed.

Images