Method for manufacturing a storage battery cell and storage battery cell

Abstract

To provide a method of manufacturing a power storage cell, capable of preventing a connecting piece from leaning in a direction away from a winding core during winding.SOLUTION: A method of manufacturing a power storage cell 1 includes: a preparing step of preparing an electrode sheet including a current collecting foil and an active material layer; a cutting step of forming a plurality of cuts 114c in the current collecting foil; and a winding step of winding the electrode sheet around a winding core 10. The current collecting foil includes an end region 114 not provided with an active material layer. In the cutting step, a plurality of the cuts 114c is formed in an end region 114d such that a coupling portion 114d is formed in the end region 114. In the winding step, the electrode sheet is wound around the winding core 10 to cause the coupling portion 114d to be fractured along the cuts 114c, and, by the fracture of the coupling portion 114d, connecting pieces 114a formed in the end region 114 are leaned 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 that houses the plate group. A plurality of notches are formed in the strip-shaped current collector of each electrode plate. The strip-shaped current collector has a plurality of connection pieces formed between the respective notches. 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] According to one aspect of the present disclosure, a method for manufacturing a storage cell includes 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 a 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. 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. The end region includes an edge in a direction orthogonal to both the one direction and a 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 so that a connecting portion including the edge in the orthogonal direction and extending along the one direction is formed in the end region. In the winding step, the connecting portion breaks along the cut as the electrode sheet is wound around the winding core, and a connection piece formed in the end region due to the breakage of the connecting portion falls toward the winding core.

[0007] A storage cell according to one aspect of the present disclosure includes a positive electrode sheet, a negative electrode sheet, and a separator, and includes an electrode body configured by a wound body in which the positive electrode sheet and the negative electrode sheet are wound with the separator interposed therebetween. Each of the positive electrode sheet and the negative electrode sheet has a current collector foil and an active material layer provided on a surface of the current collector foil. The current collector foil has a main region provided with the active material layer and arranged to overlap each other in a radial direction of the wound body, and an end region formed outside the main region in an axial direction of the wound body and not provided with the active material layer. The end regions are separated from each other in the circumferential direction and have a plurality of connection pieces that fall toward the inside in the radial direction of the wound body. Each connection piece has a cut end face formed by a cut in the current collector foil and a break end face formed inside the cut end face in the radial direction and formed by a break in the current collector foil.

Advantages of the Invention

[0008] According to the present disclosure, it is possible to provide a method for manufacturing a power storage cell and a power storage cell that can suppress the connecting piece from falling in a direction away from the winding core during winding.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0010] Embodiments of the present disclosure will be described with reference to the drawings. In the drawings referred to below, the same or corresponding members are denoted by the same reference numerals.

[0011] FIG. 1 is a partial cross-sectional view schematically showing a power storage cell according to an embodiment of the present disclosure. This power storage cell 1 is preferably mounted on a vehicle.

[0012] As shown in FIG. 1, the power storage cell 1 includes an electrode body 100, a cell case 200, a positive electrode current collector plate 310, a negative electrode current collector plate 320, and a connection 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 with the separator 130 interposed therebetween.

[0014] Figure 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 the 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 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 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 (vertical direction in FIG. 1) of the electrode body 100.

[0018] The end region 114 has a plurality of connection pieces 114a (see FIG. 3) separated from each other in the circumferential direction of the electrode body 100. Each connection piece 114a is inclined 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 where the negative electrode active material layer 126 is provided, 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 opens 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 current collector plate 310 is disposed above the electrode body 100. The positive current collector plate 310 is connected to the upper surface of each connection piece 114a in the positive current collector foil 112 by welding or the like.

[0027] The negative current collector plate 320 is disposed below the electrode body 100. The negative current collector plate 320 is connected to the upper surface of each connection piece in the negative current collector foil 122 by welding or the like.

[0028] The connection lead 330 connects the positive current collector plate 310 and the lid 220.

[0029] Next, with reference to FIGS. 2 and 3, a method for manufacturing the storage cell 1 will be described. 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 are referred to as "electrode sheets", the positive current collector foil 112 and the negative current collector foil 122 are referred to as "current collector foils", and the positive electrode active material layer 116 and the negative electrode active material layer 126 are referred to as "active material layers". In FIGS. 2 and 3, the positive electrode sheet 110 is shown as an example. Further, in FIG. 3, the illustration of the separator 130 is omitted.

[0030] In the preparation step, electrode sheets are prepared. Specifically, in the preparation step, electrode sheets including a current collector foil having a shape that extends long in one direction (the vertical direction in FIG. 2) and an active material layer provided on the surface of the current collector foil are prepared. The current collector foils of the electrode sheets 110 and 120 prepared in the preparation step have 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 the current collector foil conveyed by a conveying roll. The end regions 114, 124 are adjacent to the main regions 113, 123 in a direction orthogonal to both the one direction and the thickness direction of the current collector foil (the left-right direction in FIG. 2). 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, 124 have a shape that is continuously connected in one direction. The end regions 114, 124 include an edge portion 114b in the orthogonal direction.

[0031] In the cutting step, a plurality of cuts 114c (see FIG. 2) spaced apart from each other in one direction are formed in the current collector foil. Specifically, in the cutting step, a plurality of cuts 114c are formed, each of which is spaced apart from the edge 114b in the orthogonal direction and spaced apart from each other in one direction. As a result, in the end regions 114 and 124, a connecting portion 114d including the edge 114b in the orthogonal direction and extending along one direction is formed. In other words, in the cutting step, a plurality of cuts 114c are formed in the end regions 114 and 124 so that the connecting portion 114d is formed in the end regions 114 and 124. More specifically, in the cutting step, a plurality of cuts 114c are formed in the end regions 114 and 124 so that a connecting portion 114d that is continuously connected from one end of the end regions 114 and 124 in one direction to the other end is formed. Each cut 114c may be formed parallel to the orthogonal direction. For example, each cut 114c may be formed by a laser irradiated from the laser irradiation unit 20 as shown in FIG. 2, or may be formed by a blade. FIG. 2 shows the positive electrode sheet 110 after the cutting step among the electrode sheets.

[0032] In the winding step, the electrode sheet and the separator 130 are wound around the winding core 10. As shown in FIGS. 2 and 3, the electrode sheet is wound around the winding core 10 at a position where the active material layer overlaps the winding core 10. The separator 130 is disposed at a position that overlaps only the main regions 113 and 123.

[0033] When the electrode sheet is wound around the winding core 10, a surface pressure acts on the end regions 114 and 124 toward the winding core 10. Let this surface pressure be P [MPa], the tension of the electrode sheet be T [N], the length (width) of the end regions 114 and 124 in the orthogonal direction be W [mm], and the winding radius be 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 FIG. 3, the electrode sheet and the separator 130 are wound around the winding core 10, so that the connecting portion 114d breaks along the cut 114c, and the connecting piece 114a formed in the end regions 114, 124 falls toward the winding core 10 due to the breakage of the connecting portion 114d. More specifically, when a surface pressure acting toward the winding core 10 is applied to the end regions 114, 124 during the winding of the electrode sheet, the inner portion (the upper side in FIG. 2) in the winding direction of the pair of portions sandwiching the cut 114c in the end regions 114, 124 starts to fall toward the winding core 10 first. Therefore, a shearing force acts on the portion outside the cut 114c in the orthogonal direction, that is, on the connecting portion 114d, among the pair of portions. For this reason, 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 breakage falls toward the winding core 10 due to the surface pressure. Each connecting piece 114a formed in this way has a cut end face S1 formed by the cut in the cutting process and a fracture end face S2 formed by the breakage in the winding process.

[0036] As described above, in the method for manufacturing the power storage cell 1 according to the present embodiment, when the electrode sheet is wound around the winding core 10 in the winding process, since the end regions 114, 124 have the connecting portion 114d, a surface pressure acting toward the winding core 10 is applied to the end regions 114, 124 during the winding of the electrode sheet. Then, the connecting portion 114d breaks due to the surface pressure, and the connecting piece 114a formed by the breakage falls toward the winding core 10. Therefore, it is possible to suppress the connecting piece 114a from falling in a direction away from the winding core 10 (outward in the radial direction) during winding.

[0037] In the above embodiment, as shown in FIGS. 4 and 5, in the cutting step, a cut 114c including an inclined portion c1 that gradually inclines toward the outside in the orthogonal direction (the left side in FIG. 4) as it goes toward the outside in the winding direction (the lower side in FIG. 4) may be formed. In the example shown in FIG. 4, the cut 114c is composed of only the inclined portion c1. In the example shown in FIG. 5, the cut 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 formed by one direction and the inclined portion c1 is preferably set to be 10 degrees or more and 80 degrees or less, and more preferably set to be 30 degrees or more and 75 degrees or less.

[0038] Also, as shown in FIG. 6, the plurality of cuts 114c may include a cutting cut 114e that extends to the edge portion 114b. The cutting cut 114e divides the connecting portion 114d. The cutting cut 114e is formed at intervals of at least 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 the pi). In this example, although the connecting portion 114d is interrupted by the cutting cut 114e, since the length of the connecting portion 114d in one direction is at least the length of one turn of the electrode sheet wound around the winding core 10, the surface pressure effectively acts on the end regions 114 and 124 in the winding step.

[0039] Also, as shown in FIG. 7, in the cutting step, a plurality of cuts 114c may be formed such that the length of the connecting portion 114d in the orthogonal direction gradually decreases as it goes toward the outside in the winding direction (the lower side in FIG. 7).

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

[0041] [Aspect 1] 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 in the current collector foil that are spaced apart from each other in the one direction; A winding step of winding the electrode sheet around a winding core, and 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 a direction orthogonal 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, a plurality of cuts are formed in the end region so that a connecting portion including the edge in the orthogonal direction and extending along the one direction is formed in the end region, In the winding step, when the electrode sheet is wound around the winding core, the connecting portion breaks along the cut, and a connecting piece formed in the end region due to the breakage of the connecting portion falls toward the winding core. A method for manufacturing a storage cell.

[0042] In this method for manufacturing a storage cell, when the electrode sheet is wound around the winding core in the winding step, since the end region has a connecting portion, a surface pressure acting toward the winding core acts on the end region when the electrode sheet is wound. Then, among the pair of portions sandwiching the cut in the end region, the inner portion in the winding direction starts to fall toward the winding core first, so a shearing force acts on the portion outside the cut in the orthogonal direction among the pair of portions, that is, on the connecting portion. For this reason, the connecting portion breaks so that the cut reaches the edge of the end region, and the connecting piece formed by the breakage falls toward the winding core due to the surface pressure. Therefore, it is possible to suppress the connecting piece from falling outward during winding.

[0043] [Aspect 2] The method for manufacturing a storage cell according to Aspect 1, wherein in the cutting step, the cut including an inclined portion that is inclined so as to gradually face outward in the orthogonal direction as it goes outward in the winding direction is formed.

[0044] In this aspect, the air resistance acting on the connecting piece in the winding step is reduced. Therefore, even when the winding core is rotated at a high speed in the winding step, each connecting piece effectively falls toward the winding core.

[0045] [Aspect 3] In the cutting step, the plurality of cuts are formed in the end region so that the connecting portion that is continuously connected from one end of the end region in the one direction to the other end is formed, according to the manufacturing method of the power storage cell described in Aspect 1 or 2.

[0046] In this aspect, since the surface pressure acts stably on the connecting portion in the winding step, each connection piece falls stably toward the winding core.

[0047] [Aspect 4] In the cutting step, the plurality of cuts are formed so that the length of the connecting portion in the orthogonal direction gradually decreases toward the outside in the winding direction, according to the manufacturing method of the power storage cell described in any one of Aspects 1 to 3.

[0048] In this aspect, the connecting portion breaks stably in the winding step also at the outer part in the winding direction of the end region.

[0049] [Aspect 5] An electrode body including a wound body formed by winding a positive electrode sheet, a negative electrode sheet, and a separator, with the positive electrode sheet and the negative electrode sheet wound via the separator, Each of the positive electrode sheet and the negative electrode sheet, A current collector foil, And an active material layer provided on the surface of the current collector foil, The current collector foil, A main region where the active material layer is provided and which is arranged to overlap each other in the radial direction of the wound body, An end region formed outside the main region in the axial direction of the wound body and where the active material layer is not provided, The end region is separated from each other in the circumferential direction of the wound body and has a plurality of connection pieces that fall toward the inside in the radial direction, Each connection piece, The cut end face formed by the cut of the current collector foil, and a broken end face that is formed inside the cut end face in the radial direction and is formed by the breakage of the current collector foil, and has a power storage cell.

[0050] In this power storage cell, since each connection piece has a broken end face, an increase in the contact resistance at the welded portion between each connection piece and the current collector plate is suppressed as compared with the case where each connection piece is composed only of a cut end face. For example, when a connection piece is formed only by a cut with a laser, a melt may adhere to the end of the cut surface, and when a connection piece is formed only by a cut with a blade, a burr may occur at the end of the cut surface, so the contact resistance between each connection piece and the current collector plate may increase. On the other hand, since no melt or burr occurs on the broken end face, an increase in contact resistance is suppressed.

[0051] [Aspect 6] An electrode sheet that constitutes an electrode body in the form of a wound body by being wound together with a separator, 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, the current collector foil has a main region where the active material layer is provided, and includes an edge portion in a direction orthogonal to both the one direction and the thickness direction of the current collector foil and is continuous in the one direction, and an end region where the active material layer is not provided, and in the end region, a plurality of cuts are formed that are each spaced apart from the edge portion in the orthogonal direction and are spaced apart from each other in the one direction, the electrode sheet.

[0052] It should be noted that all aspects of the embodiments disclosed this time are illustrative in all respects and should not be considered restrictive. The scope of the present invention is shown not by the description of the above embodiments but by the claims, and further includes all modifications within the meaning and scope equivalent to the claims.

Explanation of Signs

[0053] 1 Storage cell, 100 Electrode body, 110 Positive electrode sheet, 112 Positive current collector foil, 113 Main region, 114 End region, 114a Connection piece, 114b Edge, 114c Notch, 114d Connection part, 114e Cutting notch, 116 Positive electrode active material layer, 120 Positive electrode sheet, 122 Negative current collector foil, 123 Main region, 124 End region, 200 Cell case, 210 Case body, 220 Lid, 310 Positive current collector plate, 320 Negative current collector plate, 330 Connection lead, c1 Inclined part, c2 Inner part.

Claims

1. A preparation step of preparing an electrode sheet including a current collector foil having a shape extending 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 in the current collector foil that are spaced apart from each other in the one direction; A winding step of winding the electrode sheet around a winding core, and 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 a direction orthogonal 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 so that a connecting portion including the edge in the orthogonal direction and extending along the one direction is formed in the end region. In the winding step, the connecting portion breaks along the cut as the electrode sheet is wound around the winding core, and a connecting piece formed in the end region due to the break of the connecting portion falls toward the winding core. A method for manufacturing a storage cell.

2. The method for manufacturing a storage cell according to claim 1, wherein in the cutting step, the cut including an inclined portion that inclines so as to gradually face the outside in the orthogonal direction as it faces the outside in the winding direction is formed.

3. The method for manufacturing a storage cell according to claim 1, wherein in the cutting step, the plurality of cuts are formed in the end region so that the connecting portion that is continuously connected from one end of the end region in the one direction to the other end is formed.

4. The method for manufacturing a storage cell according to claim 1, wherein in the cutting step, the plurality of cuts are formed so that the length of the connecting portion in the orthogonal direction gradually decreases as it faces the outside in the winding direction.

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