Energy storage cell

Abstract

To provide a method for manufacturing an energy storage cell that can stabilize the bending position of the connecting piece during winding. [Solution] The method for manufacturing the energy storage cell 1 comprises a preparation step of preparing an electrode sheet including a current collector foil and an active material layer; a cutting step of forming a plurality of connecting pieces 114a by forming a plurality of cuts 114c in the current collector foil; and a winding step of winding the electrode sheet around a winding core 10 while bending each of the plurality of connecting pieces 114a. The current collector foil of the electrode sheet prepared in the preparation step includes a main region 113 and an end region 114, the end region including an edge portion 114b. In the cutting step, a plurality of cuts 114c are formed in the end region 114 such that a connecting piece 114a having a wide portion a1 and a narrow portion a2 is formed between a pair of cuts 114c. In the winding step, the electrode sheet is wound around the winding core 10 while bending each connecting piece 114a at the narrow portion a2.

Description

Technical Field

[0001] The present disclosure relates to a method for manufacturing a storage battery cell and a storage battery cell.

Background Art

[0002] Japanese Patent No. 4401634 discloses a storage battery including a group of electrode plates including a positive electrode plate, a negative electrode plate, and a separator, and a battery case that houses the group of electrode plates. A plurality of cutouts are formed in the strip-shaped current collector portion of each electrode plate. The strip-shaped current collector portion has a plurality of connection pieces formed between the respective cutouts. The group of electrode plates is formed by winding these electrode plates in a spiral shape with a separator interposed therebetween.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the method for manufacturing a storage battery cell described in Japanese Patent No. 4401634, when each electrode plate is wound in a spiral shape with a separator interposed therebetween, there is a concern that the folding position of the connection piece is unstable and the connection between the connection piece and the current collector plate becomes unstable.

[0005] An object of the present disclosure is to provide a method for manufacturing a storage battery cell and a storage battery cell capable of stabilizing the folding position of the connection piece during winding.

Means for Solving the Problems

[0006] A method for manufacturing an energy storage cell according to one aspect of the present disclosure comprises: a preparation step of preparing an electrode sheet including a current collector foil having a shape that extends long in one direction and an active material layer provided on the surface of the current collector foil; a cutting step of forming a plurality of connecting pieces separated from each other in one direction by forming a plurality of cuts in the current collector foil; and a winding step of winding the electrode sheet around a winding core while bending each of the plurality of connecting pieces toward a winding core, wherein the current collector foil of the electrode sheet prepared in the preparation step includes a main region on which the active material layer is provided and an end region on which the active material layer is not provided and which has a shape that is continuously connected in one direction. The end region includes an edge in a direction perpendicular to both the one direction and the thickness direction of the current collector foil, and in the cutting step, the plurality of cuts are formed in the end region such that a connecting piece is formed between a pair of adjacent cuts in the one direction, the connecting piece having a wide portion extending from the edge toward the main region and a narrow portion connected to the inside of the wide portion in a direction perpendicular to both the one direction and the thickness direction of the current collector foil, and the length in the one direction is shorter than the length of the wide portion in the one direction, and in the winding step, the electrode sheet is wound around the winding core while bending each of the plurality of connecting pieces at the narrow portion.

[0007] A storage cell according to one aspect of the present disclosure comprises an electrode body comprising a winding body in which the positive electrode sheet and the negative electrode sheet are wound around the separator, each of the positive electrode sheet and the negative electrode sheet having a current collector foil and an active material layer provided on the surface of the current collector foil, the current collector foil having the active material layer and a main region arranged to overlap each other in the radial direction of the winding body, and an end region formed outside the main region in the axial direction of the winding body and not having the active material layer, the end region having a plurality of notches formed at intervals in the circumferential direction to define a plurality of connecting pieces that are separated from each other in the circumferential direction of the winding body and tilted inward in the radial direction, each of the plurality of notches having a slit extending radially outward from the radial edge of the end region and a curved portion connected to the outer end of the slit in the radial direction. [Effects of the Invention]

[0008] According to this disclosure, it is possible to provide a method for manufacturing an energy storage cell and an energy storage cell that can suppress the connecting piece from falling in a direction away from the winding core during winding. [Brief explanation of the drawing]

[0009] [Figure 1] This is a partial cross-sectional view schematically showing an energy storage cell in one embodiment of the present disclosure. [Figure 2] This is a schematic plan view showing the positive electrode sheet before winding. [Figure 3] This diagram schematically shows variations of the cuts and connecting pieces. [Figure 4] This diagram schematically shows variations of the cuts and connecting pieces. [Figure 5] This diagram schematically shows variations of the cuts and connecting pieces. [Modes for carrying out the invention]

[0010] Embodiments of this disclosure will be described with reference to the drawings. In the drawings referred to below, the same or equivalent components are given the same number.

[0011] Figure 1 is a schematic partial cross-sectional view showing a storage cell in one embodiment of the present disclosure. This storage cell 1 is preferably mounted in a vehicle.

[0012] As shown in Figure 1, the energy storage cell 1 comprises an electrode body 100, a cell case 200, a positive electrode current collector plate 310, a negative electrode current collector plate 320, and a connecting lead 330.

[0013] The electrode body 100 includes a positive electrode sheet 110, a negative electrode sheet 120, and a separator 130. The electrode body 100 is composed of a wound body in which the positive electrode sheet 110 and the negative electrode sheet 120 are wound around each other with the separator 130 in between.

[0014] Figure 2 is a schematic plan view showing the positive electrode sheet before winding. As shown in Figures 1 and 2, the positive electrode sheet 110 has a positive electrode current collector foil 112 and a positive electrode active material layer 116.

[0015] The positive electrode current collector foil 112 is made of a metal such as aluminum. As shown in Figure 2, before winding, the positive electrode current collector foil 112 has a shape that extends long in one direction (up and down in Figure 2). The positive electrode current collector foil 112 has a main region 113 and an end region 114.

[0016] The main region 113 is the region of the positive electrode current collector foil 112 in which the positive electrode active material layer 116 is provided. As shown in Figure 1, the main regions 113 are arranged so as to overlap each other in the radial direction of the wound body (electrode body 100).

[0017] The end region 114 is the region of the positive electrode current collector foil 112 in which the positive electrode active material layer 116 is not provided. As shown in Figure 1, the end region 114 is formed on the outside (upper side in Figure 1) of the main region 113 in the axial direction (up and down direction in Figure 1) of the electrode body 100.

[0018] The end region 114 has a plurality of connection pieces 114a (see FIG. 2) separated from each other in the circumferential direction of the electrode body 100. Each connection piece 114a is tilted inward in the radial direction. The upper surface of each connection piece 114a forms a substantially flat surface.

[0019] The negative electrode sheet 120 has a negative electrode current collector foil 122 made of a metal such as copper, and a negative electrode active material layer 126 provided on the surface of the negative electrode current collector foil 122.

[0020] The structure of the negative electrode current collector foil 122 is substantially the same as the structure of the positive electrode current collector foil 112. For this reason, the description of the negative electrode current collector foil 122 is simplified. That is, the negative electrode current collector foil 122 has a main region 123 provided with the negative electrode active material layer 126, and an end region 124 formed outside the main region 123 in the axial direction (the lower side in FIG. 1). The end region 124 has a plurality of connection pieces tilted inward in the radial direction.

[0021] The separator 130 is disposed between the positive electrode sheet 110 and the negative electrode sheet 120. More specifically, the separator 130 is disposed only between the main region 113 of the positive electrode sheet 110 and the main region 123 of the negative electrode sheet 120 adjacent to each other in the radial direction. The separator 130 is made of an insulating material and allows the permeation of ions.

[0022] The cell case 200 houses the electrode body 100. The cell case 200 also houses an electrolytic solution (not shown). The cell case 200 is sealed. The cell case 200 has a case body 210 and a lid 220.

[0023] The case body 210 is open upward. The case body 210 is made of a metal such as aluminum. The case body 210 has a bottom wall 212 and a peripheral wall 214. The bottom wall 212 is formed in a disk shape. The peripheral wall 214 stands up from the edge of the bottom wall 212 and is formed in a cylindrical shape.

[0024] The lid 220 closes the opening of the case body 210. The lid 220 is connected to the case body 210 via a sealing member 215.

[0025] The positive electrode current collector plate 310 is positioned above the electrode body 100. The positive electrode current collector plate 310 is connected to the upper surface of each connecting piece 114a of the positive electrode current collector foil 112 by welding or the like.

[0026] The negative electrode current collector plate 320 is positioned below the electrode body 100. The negative electrode current collector plate 320 is connected to the upper surface of each connecting piece in the negative electrode current collector foil 122 by welding or the like.

[0027] The connecting lead 330 connects the positive electrode current collector plate 310 and the cover 220.

[0028] Next, the manufacturing method of the energy storage cell 1 will be described with reference to Figures 2 and 3. This manufacturing method includes a preparation step, a cutting step, and a winding step. Hereinafter, the positive electrode sheet 110 and the negative electrode sheet 120 will be referred to as "electrode sheets," the positive electrode current collector foil 112 and the negative electrode current collector foil 122 will be referred to as "current collector foil," and the positive electrode active material layer 116 and the negative electrode active material layer 126 will be referred to as "active material layers." In Figures 2 and 3, the positive electrode sheet 110 is shown as an example. Also, in Figure 3, the separator 130 is not shown.

[0029] In the preparation step, electrode sheets are prepared. Specifically, in the preparation step, electrode sheets are prepared that include a current collector foil having a shape that extends long in one direction (up and down direction in Figure 2) and an active material layer provided on the surface of the current collector foil. The current collector foil of each electrode sheet 110, 120 prepared in the preparation step has a main region 113, 123 and an end region 114, 124. The main regions 113, 123 are formed, for example, by providing an active material layer on a current collector foil that is conveyed by a conveyor roll. The end regions 114, 124 are adjacent to the main regions 113, 123 in an orthogonal direction (left and right direction in Figure 2) that is perpendicular to both the unidirectional direction and the thickness direction of the current collector foil. The length of the main regions 113, 123 in the orthogonal direction is set to, for example, 80 mm, and the length of the end regions 114, 124 in the orthogonal direction is set to, for example, 5 mm. The end regions 114 and 124 have a shape that is continuously connected in one direction. The end regions 114 and 124 include an edge portion 114b in the orthogonal direction.

[0030] In the cutting process, multiple cuts 114c are formed in the current collector foil, thereby forming multiple connecting pieces 114a that are separated from each other in one direction. Specifically, in the cutting process, multiple cuts 114c are formed in the end region 114 such that connecting pieces 114a having a wide portion a1 and a narrow portion a2 are formed.

[0031] As shown in Figure 2, in the cutting process, a notch 114c having a slit c1 and a widening portion c2 is formed in the end regions 114, 124. The slit c1 extends from the edge portion 114b toward the main regions 113, 123. The slit c1 may be formed parallel to the orthogonal direction. The widening portion c2 is connected to the slit c1. The widening portion c2 has a shape in which its length in one direction gradually increases as it approaches the main regions 113, 123 from the slit c1. In this embodiment, the widening portion c2 is formed in a circular shape. This widening portion c2 constitutes a curved portion having a shape that curves so as to be convex toward the main regions 113, 123. The length of the slit c1 in one direction is, for example, 0.05 mm, and the length of the widening portion c2 in one direction is, for example, 0.1 mm. The length of the notch 114c in the orthogonal direction is, for example, about 4 mm. For example, each notch 114c may be formed by a laser irradiated from the laser irradiation unit 20, as shown in Figure 2, or by a cutting tool. Figure 2 shows the positive electrode sheet 110 after the notching process.

[0032] In the end regions 114 and 124, multiple connecting pieces 114a are defined by multiple notches 114c. As shown in Figure 2, each connecting piece 114a has a wide portion a1 and a narrow portion a2.

[0033] The wide portion a1 extends from the edge portion 114b toward the main regions 113 and 123. The wide portion a1 is formed between a pair of slits c1 that are adjacent to each other in one direction.

[0034] The narrow section a2 connects to the inside of the wide section a1 in the orthogonal direction. The length L2 of the narrow section a2 in one direction is shorter than the length L1 of the wide section a1 in the same direction. The narrow section a2 is formed between a pair of wide sections c2 that are adjacent to each other in one direction.

[0035] In the winding process, the electrode sheet and separator 130 are wound around the winding core 10 (see Figure 2). As shown in Figure 2, the electrode sheet is wound around the winding core 10 at a position where the active material layer overlaps with the winding core 10. The separator 130 is positioned to overlap only with the main regions 113 and 123.

[0036] In the winding process, the electrode sheet and separator 130 are wound around the winding core 10 while each connecting piece 114a is bent toward the winding core 10. More specifically, in the winding process, the electrode sheet and separator 130 are wound around the winding core 10 while each connecting piece 114a is bent at the narrow portion a2.

[0037] As described above, in the manufacturing method of the energy storage cell 1 in this embodiment, a narrow portion a2 is formed inside the wide portion a1 in the orthogonal direction during the cutting process. Since the bending rigidity of this narrow portion a2 is lower than that of the wide portion a1, the bending position of each connecting piece 114a is effectively determined to be in the narrow portion a2 during the winding process.

[0038] In the above embodiment, the shape of the spreading portion c2 formed in the cutting process may be formed as shown in Figures 3 to 5. In the example shown in Figure 3, the corners of the spreading portion c2 in one direction are formed in a curved shape. In the example shown in Figure 4, the spreading portion c2 is formed in a rectangular shape. It is preferable that each corner of the rectangle is formed in a curved shape. In the example shown in Figure 5, the spreading portion c2 branches outwards from each other in one direction.

[0039] Those skilled in the art will understand that the exemplary embodiments described above are specific examples of the following embodiments.

[0040] [Aspect 1] Preparation steps for preparing an electrode sheet comprising a current collector foil having a shape that extends long in one direction, and an active material layer provided on the surface of the current collector foil, A cutting step to form multiple connecting pieces that are separated from each other in one direction by forming multiple cuts in the current collector foil, The process includes a winding step of winding the electrode sheet around the winding core while bending each of the plurality of connecting pieces toward the winding core, The current collector foil of the electrode sheet prepared in the preparation step includes a main region on which the active material layer is provided, and an end region on which the active material layer is not provided and which has a shape that is continuously connected in one direction, wherein the end region includes an edge in an orthogonal direction perpendicular to both the one direction and the thickness direction of the current collector foil. In the cutting process, the plurality of cuts are formed in the end region such that a connecting piece is formed between a pair of cuts adjacent to each other in one direction, the connecting piece having a wide portion extending from the edge toward the main region and a narrow portion connected to the inside of the wide portion in a direction perpendicular to both the one direction and the thickness direction of the current collector foil, and the length in the one direction being shorter than the length of the wide portion in the one direction. A method for manufacturing an energy storage cell, wherein in the winding step, the electrode sheet is wound around the winding core while bending each of the plurality of connecting pieces at the narrow portion.

[0041] In this energy storage cell manufacturing method, a narrow section is formed inside the wider section in the orthogonal direction during the cutting process. Since the bending rigidity of this narrow section is lower than that of the wider section, the bending position of each connecting piece is effectively determined to be in the narrow section during the winding process.

[0042] [Aspect 2] A method for manufacturing an energy storage cell according to Embodiment 1, wherein the cutting step involves forming a cut having a slit that extends from the edge toward the main region and defines the wide portion, and a wide portion that gradually increases in length in one direction as it approaches the main region from the slit and defines the narrow portion.

[0043] [Aspect 3] The electrode body comprises a positive electrode sheet, a negative electrode sheet, and a separator, and is composed of a wound body in which the positive electrode sheet and the negative electrode sheet are wound around the separator, Each of the positive electrode sheet and the negative electrode sheet is, Current collector foil and The current collector foil has an active material layer provided on its surface, The aforementioned current collector foil is The active material layer is provided, and the main regions are arranged so as to overlap each other in the radial direction of the wound body, The winding body has an end region formed on the outside of the main region in the axial direction, where the active material layer is not provided, The end region has a plurality of notches formed at intervals in the circumferential direction to define a plurality of connecting pieces that are separated from each other in the circumferential direction of the wound body and are bent inward in the radial direction, Each of the aforementioned multiple cuts is A slit extending radially outward from the edge in the radial direction within the end region, A storage cell having a curved portion connected to the outer end of the slit in the radial direction.

[0044] In this energy storage cell, each notch has a curved section, which suppresses stress concentration at these curved sections. Therefore, when an external force is applied to the connecting piece due to the expansion and contraction of the electrode body or a vehicle collision, the notch is prevented from separating at its base.

[0045] [Aspect 4] An electrode sheet that, when wound together with a separator, constitutes an electrode body consisting of a wound body, A current collector foil having a shape that extends long in one direction, The current collector foil has an active material layer provided on its surface, The aforementioned current collector foil is The main region where the active material layer is provided, It includes an edge portion in an orthogonal direction perpendicular to both the aforementioned one direction and the thickness direction of the current collector foil, and is continuous in the aforementioned one direction, and has an end region in which the active material layer is not provided, The end region has a plurality of notches formed at intervals in one direction to define a plurality of connecting pieces that are connected to the current collector, Each of the aforementioned multiple cuts is A slit extending radially outward from the edge in the radial direction within the end region, An electrode sheet having a curved portion connected to the outer end of the slit in the radial direction.

[0046] It should be noted that the embodiments disclosed herein are illustrative in all respects and not restrictive. The scope of the present invention is indicated by the claims rather than the description of the embodiments above, and further includes all modifications within the meaning and scope equivalent to the claims. [Explanation of Symbols]

[0047] 1 Energy storage cell, 100 Electrode body, 110 Positive electrode sheet, 112 Positive electrode current collector foil, 113 Main region, 114 End region, 114a Connecting piece, 114b Edge, 114c Notch, 114d Connecting portion, 114e Cutting notch, 116 Positive electrode active material layer, 120 Positive electrode sheet, 122 Negative electrode current collector foil, 123 Main region, 124 End region, 200 Cell case, 210 Case body, 220 Lid, 310 Positive electrode current collector plate, 320 Negative electrode current collector plate, 330 Connecting lead, a1 Wide portion, a2 Narrow portion, c1 Slit, c2 Wide portion.

Claims

[Claim 1] The electrode body comprises a winding body having a positive electrode sheet, a negative electrode sheet, and a separator, wherein the positive electrode sheet and the negative electrode sheet are wound around the separator, Each of the positive electrode sheet and the negative electrode sheet is, Current collector foil and The current collector foil has an active material layer provided on its surface, The aforementioned current collector foil is The active material layer is provided, and the main regions are arranged so as to overlap each other in the radial direction of the wound body, The winding body has an end region formed on the outside of the main region in the axial direction, where the active material layer is not provided, The end region has a plurality of notches formed at intervals in the circumferential direction to define a plurality of connecting pieces that are separated from each other in the circumferential direction of the wound body and are bent inward in the radial direction, Each of the aforementioned multiple cuts is A slit extending radially outward from the edge in the radial direction within the end region, A storage cell having a curved portion connected to the outer end of the slit in the radial direction.

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