Energy storage cell

Abstract

To provide a manufacturing method for a battery cell capable of preventing a connecting piece from falling in a direction away from a winding core during winding.SOLUTION: A manufacturing method for a storage cell 1 includes: a preparation step for preparing an electrode sheet including a current collecting foil and an active material layer; a cutting step for forming a plurality of cuts 114c in the current collecting foil; and a winding step for winding the electrode sheet around a winding core 10. The current collecting foil includes an end part area 114 on which no active material layer is provided. In the cutting step, a plurality of cuts 114c is formed in an end part area 114 so that a connecting part 114d is formed in the end part area 114. In the winding step, by winding the electrode sheet around the winding core 10, the connecting part 114d is broken along the cuts 114c, and a connecting piece 114a formed in the end part 114 by the breaking of the connecting part 114d falls toward the winding core 10.SELECTED DRAWING: Figure 3

Description

Technical Field

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

Background Art

[0002] Japanese Patent No. 4401634 discloses a storage battery including a plate group including a positive electrode plate, a negative electrode plate, and a separator, and a battery case housing the plate group. 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 cutouts. The plate group 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 cell described in Japanese Patent No. 4401634, when each electrode plate is wound in a spiral shape with a separator interposed therebetween, the connection piece may fall in a direction away from the winding core (outward in the radial direction of the winding core).

[0005] An object of the present disclosure is to provide a method for manufacturing a storage cell and a storage cell capable of suppressing the connection piece from falling in a direction away from the winding core 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 cuts spaced apart from each other in the one direction in the current collector foil; and a winding step of winding the electrode sheet around a winding core, wherein the current collector foil of the electrode sheet prepared in the preparation step includes an end region where the active material layer is not provided, and 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, and has a shape that is continuously connected in the one direction, the cutting step of forming the plurality of cuts in the end region such that a connecting portion is formed in the end region including the edge in the orthogonal direction and extending along the one direction, and the winding step of winding the electrode sheet around the winding core so that the connecting portion breaks along the cut, and the connecting piece formed in the end region falls toward the winding core due to the breakage of the connecting 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 comprises a current collector foil and an active material layer provided on the surface of the current collector foil, the current collector foil comprises a main region having the active material layer and 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 connecting pieces separated from each other in the circumferential direction and tilted inward in the radial direction of the winding body, each connecting piece comprising a notched end face formed by a notch in the current collector foil and a broken end face formed inside the notched end face in the radial direction and formed by a break in the current collector foil It has, and [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 a 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 is a schematic perspective view showing the winding process in which the electrode sheet is wound onto the winding core. [Figure 4] This diagram schematically shows variations in the type of cut. [Figure 5] This diagram schematically shows variations in the type of cut. [Figure 6] This diagram schematically shows modified examples of the connecting portion and the cutout. [Figure 7] This diagram schematically shows modified examples of the connecting portion and the cutout. [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 formed of a wound body in which the positive electrode sheet 110 and the negative electrode sheet 120 are wound with the separator 130 interposed therebetween.

[0014] FIG. 2 is a plan view schematically showing the positive electrode sheet before winding. As shown in FIGS. 1 and 2, the positive electrode sheet 110 includes 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. The positive electrode current collector foil 112 has a main region 113 and an end region 114.

[0016] The main region 113 is a region of the positive electrode current collector foil 112 where the positive electrode active material layer 116 is provided. The main regions 113 are arranged to overlap each other in the radial direction of the wound body (electrode body 100).

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

[0018] The end region 114 has a plurality of connection pieces (see FIG. 3) 114a 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] As shown in FIG. 3, each connection piece 114a has a cut end face S1 and a broken end face S2. The cut end face S1 is an end face formed by cutting the end region 114 of the positive electrode current collector foil 112. The broken end face S2 is formed inside the cut end face S1 in the radial direction. The broken end face S2 is an end face formed by breaking the end region 114 of the positive electrode current collector foil 112.

[0020] 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.

[0021] The structure of the negative electrode current collector foil 122 is substantially the same as that of the positive electrode current collector foil 112. Therefore, 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 that are inclined inward in the radial direction, and each connection piece has a cut end face and a broken end face.

[0022] 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 that are adjacent to each other in the radial direction. The separator 130 is made of an insulating material and allows the permeation of ions.

[0023] 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.

[0024] 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 disc shape. The peripheral wall 214 stands up from the edge of the bottom wall 212 and is formed in a cylindrical shape.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] The connecting lead 330 connects the positive electrode current collector plate 310 and the cover 220.

[0029] 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.

[0030] 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 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. Regions 113 and 123 are formed, for example, by providing an active material layer on a current collector foil that is transported by a transport roll. End regions 114 and 124 are adjacent to the main regions 113 and 123 in an orthogonal direction (left-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 and 123 in the orthogonal direction is set to, for example, 80 mm, and the length of the end regions 114 and 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.

[0031] In the cutting process, multiple notches 114c (see Figure 2) are formed in the current collector foil, spaced apart from each other in one direction. Specifically, in the cutting process, multiple notches 114c are formed, each spaced apart from the edge portion 114b in a direction perpendicular to it, and spaced apart from each other in one direction. As a result, a connecting portion 114d is formed in the end regions 114, 124, which includes the edge portion 114b in the perpendicular direction and extends along one direction. In other words, in the cutting process, multiple notches 114c are formed in the end regions 114, 124 such that a connecting portion 114d is formed in the end regions 114, 124. More specifically, in the cutting process, multiple notches 114c are formed in the end regions 114, 124 such that a connecting portion 114d is formed that extends continuously from one end to the other end of the end regions 114, 124 in one direction. Each notch 114c may be formed parallel to the perpendicular direction. 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 winding process, the electrode sheet and separator 130 are wound around the winding core 10. As shown in Figures 2 and 3, 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 so as to overlap only with the main regions 113 and 123.

[0033] When the electrode sheet is wound onto the winding core 10, a surface pressure acts on the end regions 114 and 124 toward the winding core 10. If this surface pressure is P [MPa], the tension of the electrode sheet is T [N], the length (width) of the end regions 114 and 124 in the orthogonal direction is W [mm], and the winding radius is R [mm], then the surface pressure P is expressed by the following formula.

[0034] P = T / (WR)

[0035] Therefore, in the winding process, as shown in Figure 3, the connecting portion 114d breaks along the notch 114c as the electrode sheet and separator 130 are wound around the winding core 10, and the connecting piece 114a formed in the end regions 114,124 due to the breakage of the connecting portion 114d collapses toward the winding core 10. More specifically, when surface pressure is applied toward the winding core 10 to the end regions 114,124 during the winding of the electrode sheet, the inner portion (upper side in Figure 2) of the pair of portions of the end regions 114,124 that sandwich the notch 114c begins to collapse toward the winding core 10 first, so a shear force is applied to the outer portion of the pair of portions toward the notch 114c in the orthogonal direction, i.e., the connecting portion 114d. Therefore, the connecting portion 114d breaks so that the cut 114c reaches the edge 114b of the end region 114, and the connecting piece 114a formed by the break bends toward the winding core 10 due to surface pressure. Each connecting piece 114a formed in this way has a cut end face S1 formed by the cut in the cut process and a broken end face S2 formed by the break in the winding process.

[0036] As described above, in the manufacturing method of the energy storage cell 1 in this embodiment, when the electrode sheet is wound around the winding core 10 during the winding process, the end regions 114 and 124 are connected. Because it has portion 114d, surface pressure is applied to the end regions 114 and 124 toward the winding core 10 when the electrode sheet is wound. This surface pressure causes the connecting portion 114d to break, and the connecting piece 114a formed by the breakage bends toward the winding core 10. Therefore, bending of the connecting piece 114a toward the winding core 10 (outward in the radial direction) is suppressed during winding.

[0037] In the above embodiment, as shown in Figures 4 and 5, the notching process may form a notch 114c that includes an inclined portion c1 which gradually slopes outward in the orthogonal direction (left side in Figure 4) as it moves outward in the winding direction (downward in Figure 4). In the example shown in Figure 4, the notch 114c consists only of the inclined portion c1. In the example shown in Figure 5, the notch 114c has an inclined portion c1 and an inner portion c2 formed inside the inclined portion c1 in the orthogonal direction. The inner portion c2 is formed parallel to the orthogonal direction. The angle θ between one direction and the inclined portion c1 is preferably set to 10 degrees or more and 80 degrees or less, and more preferably to 30 degrees or more and 75 degrees or less.

[0038] Furthermore, as shown in Figure 6, the multiple notches 114c may include cutting notches 114e that extend to the edge portion 114b. The cutting notches 114e divide the connecting portion 114d. The cutting notches 114e are formed at intervals greater than or equal to the length of one turn of the electrode sheet wound around the winding core 10 (the product of the diameter of the electrode sheet and pi). In this example, although the connecting portion 114d is interrupted by the cutting notches 114e, the length of the connecting portion 114d in one direction is greater than or equal to the length of one turn of the electrode sheet wound around the winding core 10, so the surface pressure is effectively applied to the end regions 114, 124 during the winding process.

[0039] Furthermore, as shown in Figure 7, in the cutting process, multiple cuts 114c may be formed such that the length of the connecting portion 114d in the orthogonal direction gradually decreases as it moves outward in the winding direction (downward in Figure 7).

[0040] Those skilled in the art will understand that the exemplary embodiments described above are specific examples of the following embodiments.

[0041] [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 in which a plurality of cuts are formed in the current collector foil that are spaced apart from each other in one direction, The process includes a winding step of winding the electrode sheet around a winding core, The current collector foil of the electrode sheet prepared in the preparation step includes an end region where the active material layer is not provided, and 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, and has a shape that is continuously connected in the one direction. In the cutting step, the plurality of cuts are formed in the end region such that a connecting portion is formed in the end region that includes the edge in the orthogonal direction and extends along 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, causing the connecting portion to break along the notch, and the connecting piece formed in the end region due to the breaking of the connecting portion to fall toward the winding core.

[0042] In this method of manufacturing energy storage cells, when the electrode sheet is wound around the core during the winding process, the end region has a connecting portion, so a surface pressure acts on the end region toward the core during the winding of the electrode sheet. As a result, the inner portion of the pair of portions that sandwich the notch in the end region begins to bend toward the core first, and a shear force acts on the outer portion of the pair of portions perpendicular to the notch, i.e., the connecting portion. Therefore, the connecting portion breaks so that the cut reaches the edge of the end region, and the connecting piece formed by the break bends toward the winding core due to the surface pressure. Thus, the bending of the connecting piece outward during winding is suppressed.

[0043] [Aspect 2] The method for manufacturing an energy storage cell according to Embodiment 1, wherein the cutting step involves forming a cut that includes an inclined portion which gradually slopes outward in the orthogonal direction as it moves outward in the winding direction.

[0044] In this embodiment, the air resistance acting on the connecting pieces during the winding process is reduced. Therefore, even when the winding core is rotated at high speed during the winding process, each connecting piece effectively bends toward the winding core.

[0045] [Aspect 3] A method for manufacturing an energy storage cell according to embodiment 1 or 2, wherein in the cutting step, the plurality of cuts are formed in the end region such that a connecting portion is formed that is continuously connected from one end to the other end of the end region in one direction.

[0046] In this embodiment, the surface pressure is applied stably to the connecting portion during the winding process, so that each connecting piece stably tilts toward the winding core.

[0047] [Aspect 4] A method for manufacturing an energy storage cell according to any one of embodiments 1 to 3, wherein in the cutting step, the plurality of cuts are formed such that the length of the connecting portion in the orthogonal direction gradually decreases as the cutting step moves outward in the winding direction.

[0048] In this embodiment, the connecting portion breaks stably during the winding process, even in the outer portion of the end region in the winding direction.

[0049] [Aspect 5] 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 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 connecting piece is The notched end surface formed by the notch in the current collector foil, A storage cell having a fractured end face formed on the inside of the notched end face in the radial direction, and formed by the fracture of the current collector foil.

[0050] In this energy storage cell, since each connecting piece has a fractured end face, the increase in contact resistance at the weld between each connecting piece and the current collector plate is suppressed compared to when each connecting piece is composed only of a notched end face. For example, if a connecting piece is formed only by laser cutting, molten material may adhere to the edges of the cut surface, and if a connecting piece is formed only by cutting with a blade, burrs may form on the edges of the cut surface, which can increase the contact resistance between each connecting piece and the current collector plate. In contrast, since no molten material or burrs are formed on the fractured end surface, the increase in contact resistance is suppressed.

[0051] [Aspect 6] 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, An electrode sheet having a plurality of notches formed in the end region, each notch spaced apart from the edge in the orthogonal direction and spaced apart from each other in one direction.

[0052] 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]

[0053] 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 part, 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, c1 inclined section, c2 inner section.

Claims

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 connecting pieces that are separated from each other in the circumferential direction of the wound body and are bent inward in the radial direction. The connecting piece has an outer end face formed on the outside in the winding direction of the winding body, The outer end face includes an inclined portion that, when viewed from the axial direction, slopes outward in the winding direction as it moves inward in the radial direction, in a power storage cell.

2. The energy storage cell according to Claim 1, wherein the angle between the inclined portion and the longitudinal direction of the electrode body when the electrode body is laid out in a sheet shape without being wound is 10 degrees or more and 80 degrees or less.

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