JP7800510B2 - Electrode assembly manufacturing method - Google Patents

Description

This disclosure relates to a method for manufacturing an electrode assembly.

JP 2018-166080 A discloses a method for manufacturing a secondary battery, which includes the steps of winding a stack of a positive electrode sheet, a negative electrode sheet, and a separator to form a flat wound body, and cutting a portion of the flat wound body to form a laminate. The flat wound body includes a bent portion formed by bending the positive electrode sheet, the negative electrode sheet, and the separator, and the laminate is formed by cutting the bent portion.

JP 2018-166080 A

There is a demand for simpler manufacturing methods for so-called stacked electrode bodies.

The object of the present disclosure is to provide a method for manufacturing an electrode assembly that allows for the easy production of a stacked electrode assembly.

A method for manufacturing an electrode assembly according to one aspect of the present disclosure includes a winding step in which a wound assembly is formed by winding a positive electrode and a negative electrode with a separator interposed therebetween; a compression step in which the wound assembly is compressed from both radial sides to form a compressed wound assembly; and a cutting step in which the compressed wound assembly is cut by moving a cutting member from the inside to the outside of the compressed wound assembly in an orthogonal direction that is orthogonal to both the direction in which the wound assembly is compressed in the compression step and the central axis of the wound assembly.

This disclosure provides a method for manufacturing an electrode assembly that allows for easy production of a stacked electrode assembly.

FIG. 1 is a perspective view schematically illustrating a storage cell according to an embodiment of the present disclosure. FIG. 2 is a cross-sectional view of the storage cell shown in FIG. 1 . 1A to 1C are diagrams schematically showing a method for manufacturing an electrode body. 1A to 1C are diagrams schematically showing a method for manufacturing an electrode body. 1A to 1C are diagrams schematically showing a method for manufacturing an electrode body. 10A to 10C are diagrams schematically showing a modified example of the method for manufacturing the electrode body.

Embodiments of the present disclosure will be described with reference to the drawings. Note that in the drawings referenced below, identical or equivalent components are designated by the same numbers.

Figure 1 is a perspective view schematically illustrating a storage cell according to one embodiment of the present disclosure. Figure 2 is a cross-sectional view of the storage cell shown in Figure 1.

As shown in Figures 1 and 2, the energy storage cell 1 includes an electrode assembly 100, a cell case 200, a pair of external terminals 300, a pair of connecting members 400, and an insulating member 500.

The electrode assembly 100 is a so-called laminated type. The electrode assembly 100 includes multiple electrodes 110, 120 and a separator 130.

The multiple electrodes 110, 120 are arranged in one direction (a direction perpendicular to the paper surface in Figure 2). The multiple electrodes 110, 120 include multiple positive electrodes 110 and multiple negative electrodes 120.

Each positive electrode 110 is formed in a rectangular shape that is long in the width direction (a direction perpendicular to both one direction and the up-down direction). Each positive electrode 110 has a positive electrode current collector foil and positive electrode active material layers provided on both sides of the positive electrode current collector foil. As shown in Figure 2, the positive electrode current collector foil has a positive electrode tab 112p that does not have a positive electrode active material layer. The positive electrode tab 112p protrudes toward one side in the width direction.

Each negative electrode 120 is formed in a rectangular shape that is elongated in the width direction. Each negative electrode 120 has a negative electrode current collector foil and a negative electrode active material layer provided on both sides of the negative electrode current collector foil. As shown in FIG. 2, the negative electrode current collector foil has a negative electrode tab 122n that does not have a negative electrode active material layer. The negative electrode tab 122n protrudes toward the other side in the width direction.

The separator 130 provides insulation between the positive electrode 110 and the negative electrode 120. The separator 130 is made of an insulating material and has tiny voids that allow ions to pass through.

The cell case 200 houses the electrode assembly 100. The cell case 200 contains an electrolyte (not shown). The cell case 200 is sealed. The cell case 200 has a case body 210 and a lid 220.

The case body 210 has an opening that faces upward. The case body 210 is made of a metal such as aluminum. As shown in FIG. 2, the case body 210 has a bottom wall 212 and peripheral walls 214. The bottom wall 212 is formed in a rectangular, flat plate shape. The peripheral wall 214 stands upright from the bottom wall 212. The peripheral wall 214 is formed in a rectangular cylindrical shape. The length of the peripheral wall 214 in the width direction is longer than the length of the peripheral wall 214 in the thickness direction. The length of the peripheral wall 214 in the height direction is longer than the length of the peripheral wall 214 in the thickness direction.

The lid 220 closes the opening of the case body 210. The lid 220 is connected to the opening by welding or the like. The lid 220 is formed in a flat plate shape. The lid 220 is made of a metal such as aluminum. The lid 220 has a pressure release valve 222 and a sealing member 224.

The pressure release valve 222 is formed in the center of the lid 220. The pressure release valve 222 is configured to rupture when the internal pressure of the cell case 200 reaches or exceeds a predetermined pressure. When the pressure release valve 222 ruptures, gas within the cell case 200 is released to the outside of the cell case 200 through the pressure release valve 222, thereby reducing the internal pressure of the cell case 200.

The sealing member 224 seals the liquid filling port h formed in the lid 220. The liquid filling port h is a through-hole used to inject electrolyte into the cell case 200 during the manufacturing process of the energy storage cell 1. After electrolyte is injected into the case body 210 through the liquid filling port h, the liquid filling port h is sealed by the sealing member 224.

A pair of external terminals 300 are fixed onto the cell casing 200. One of the pair of external terminals 300 is a positive electrode external terminal, and the other is a negative electrode external terminal. Each external terminal 300 is fixed to the upper surface of the lid 220 via an upper insulating part 510 (described below). Each external terminal 300 is made of a metal such as aluminum. Each external terminal 300 is formed, for example, in a rectangular parallelepiped shape. A bus bar (not shown) is connected to each external terminal 300 by welding or the like.

A pair of connecting members 400 connect the multiple electrode tabs 112p, 122n to the external terminal 300. One connecting member 400 connects the multiple positive electrode tabs 112p to the positive electrode external terminal 300, and the other connecting member 400 connects the multiple negative electrode tabs 122n to the negative electrode external terminal 300. Since each of the pair of connecting members 400 has substantially the same structure, only one of the connecting members 400 will be described below.

The connecting member 400 has a current collecting tab 410, a sub-tab 420, and a connecting pin 430.

The current collecting tab 410 has a side portion 412 and an upper portion 414. The side portion 412 is located on the side of the electrode assembly 100 in the width direction. The upper portion 414 is located above the electrode assembly 100. The upper portion 414 extends from the upper end of the side portion 412 toward the inside in the width direction.

The subtab 420 connects multiple positive electrode tabs 112p to the current collecting tab 410. One end 422 of the subtab 420 is connected to the multiple positive electrode tabs 112p by welding or the like, and the other end 424 of the subtab 420 is connected to the side portion 412 of the current collecting tab 410 by welding or the like.

The connecting pin 430 connects the current collecting tab 410 and the external terminal 300. The connecting pin 430 connects the upper portion 414 and the external terminal 300. Specifically, the lower end of the connecting pin 430 is inserted into a through hole provided in the upper portion 414 and connected to the upper portion 414 by welding or the like, and the upper end of the connecting pin 430 is inserted into a through hole provided in the external terminal 300 and connected to the external terminal 300 by welding, crimping or the like.

The insulating member 500 provides insulation between the cell case 200 and the connecting member 400. The insulating member 500 has an upper insulating portion 510, a lower insulating portion 520, an insulator 530, and an insulating plate 540.

The upper insulating part 510 is fixed to the upper surface of the lid 220. The upper insulating part 510 is disposed between the lid 220 and the external terminal 300. The upper insulating part 510 has an insertion hole through which the connecting pin 430 is inserted.

The lower insulating part 520 is fixed to the underside of the lid 220. The lower insulating part 520 is disposed between the lid 220 and the upper part 414 and the lower part of the connecting pin 430. The lower insulating part 520 has an insertion hole through which the connecting pin 430 is inserted.

The insulator 530 is positioned between the connecting pin 430 and the lid 220. The insulator 530 is cylindrical and surrounds the connecting pin 430.

The insulating plate 540 is fixed to the underside of the upper portion 414. The insulating plate 540 is disposed above the electrode assembly 100. Through holes are provided in the insulating plate 540 in the portions located below the pressure release valve 222 and below the liquid inlet port h.

Next, the manufacturing process for the electrode assembly 100 will be described with reference to Figures 3 to 5. The manufacturing method for the electrode assembly 100 includes a winding process, a compression process, and a cutting process.

In the winding process, the positive electrode 110 and the negative electrode 120 are wound with the separator 130 interposed therebetween to form the wound body 101.

In the compression process, as shown by arrows AR3 in Figure 3, the wound body 101 is compressed from both radial sides of the wound body 101 to form a compressed wound body 102 (see Figure 4). The wound body 101 is compressed using a compression jig (not shown).

In the cutting process, the compressed wound body 102 is cut by moving a cutting member 10, such as a blade, from the inside to the outside of the compressed wound body 102 in an orthogonal direction (left-right direction in Figure 4) that is orthogonal to both the direction in which the wound body 101 is compressed in the compression process and the central axis C of the wound body 101. This forms the electrode body 100. The cutting process may be performed with the compressed wound body 102 compressed by the compression jig. Note that Figure 5 shows the electrode body 100 formed in the cutting process.

In the cutting process, it is preferable to cut the compressed wound body 102 with the cutting member 10 while collecting dust on the outside of the compressed wound body 102 in the orthogonal direction (the direction of movement of the cutting member 10). Dust collection may be performed, for example, by a dust collector 20 (see Figure 4).

In the winding process, it is preferable to form a wound body 101 having slits formed radially aligned with the portion 101A (see Figure 3) of the compressed wound body 102 that will be cut in the cutting process by winding the positive electrode 110, negative electrode 120, and separator 130 while making slits at predetermined positions using a laser or the like in at least one of the positive electrode 110, negative electrode 120, and separator 130. It is also possible to form slits in at least one of the positive electrode 110, negative electrode 120, and separator 130 before the winding process, and then wind them in the winding process.

As described above, in the manufacturing method of the electrode assembly 100 in this embodiment, the compressed wound body 102 is cut with the cutting member 10 to easily form a laminated electrode assembly 100 in which the positive electrode 110 and the negative electrode 120 are stacked with the separator 130 interposed therebetween.

In the cutting process, the cutting member 10 may be moved along the orthogonal direction, and the compressed wound body 102 may be pushed open from the inside of the compressed wound body 102 in the direction opposite to the direction in which the wound body 101 is compressed in the compression process, as shown by arrow AR6 in Figure 6. The operation of pushing open the compressed wound body 102 is performed using a jig (not shown).

In addition, during the compression process, a section 102A (see FIG. 4) of the compressed wound body 102 to be cut during the cutting process may be pressed from the inside of the compressed wound body 102 to form an outward recess in the perpendicular direction in advance in the section 102A to be cut. Note that the pressing of the section 102A to be cut is performed using a pressing jig (not shown).

Furthermore, if a slit is formed in the portion 101A of the wound body 101, the wound body 101 may be compressed in the compression process so that the portion 101A breaks starting from the slit. In this case, the cutting process is omitted.

It will be understood by those skilled in the art that the exemplary embodiments described above are specific examples of the following aspects:

[Aspect 1]
a winding step of winding the positive electrode and the negative electrode with a separator interposed therebetween to form a wound body;
a compressing step of compressing the wound body from both sides in the radial direction of the wound body to form a compressed wound body;
a cutting step of cutting the compressed wound body by moving a cutting member from the inside to the outside of the compressed wound body along an orthogonal direction that is orthogonal to both the direction in which the wound body is compressed in the compression step and the central axis of the wound body.

In this electrode assembly manufacturing method, a laminated electrode assembly in which positive and negative electrodes are stacked with a separator between them can be easily formed by cutting the compressed wound body with a cutting tool.

[Aspect 2]
the winding step involves winding the positive electrode, the negative electrode, and the separator while making slits at predetermined positions in at least one of the positive electrode, the negative electrode, and the separator, thereby forming the wound body having the slits formed so as to be aligned in the radial direction at a portion of the compressed wound body that is to be cut in the cutting step.

This configuration makes it easier to cut the compressed wound body during the cutting process.

[Aspect 3]
Aspect 3. The method for manufacturing an electrode assembly according to aspect 1 or 2, wherein in the cutting step, the compressed wound body is cut with the cutting member while collecting dust on an outside of the compressed wound body in the orthogonal direction.

In this configuration, even if cut pieces (foreign matter) are generated when the compressed wound body is cut by the cutting member, the cut pieces are prevented from scattering or becoming mixed into the electrode body.

[Aspect 4]
Aspect 4. The method for manufacturing an electrode assembly according to any one of aspects 1 to 3, wherein in the cutting step, the cutting member is moved along the orthogonal direction, and the compressed wound body is pushed open from inside the compressed wound body in a direction opposite to a direction in which the wound body is compressed in the compressing step.

This configuration facilitates cutting of the compressed wound body during the cutting process.

[Aspect 5]
A method for manufacturing an electrode body according to any one of aspects 1 to 4, wherein in the compression step, a portion of the compressed wound body to be cut in the cutting step is pressed from the inside of the compressed wound body, thereby forming an outward recess in the orthogonal direction in advance in the portion to be cut.

In this embodiment, the cutting member more reliably cuts the portion to be cut during the cutting process.

The embodiments disclosed herein are illustrative in all respects and should not be considered limiting. The scope of the present invention is indicated by the claims, not by the description of the above embodiments, and further includes all modifications within the meaning and scope of the claims.

1 Energy storage cell, 10 Cutting member, 20 Dust collector, 100 Electrode body, 101 Wound body, 102 Compressed wound body, 110 Positive electrode, 112 Positive electrode current collector foil, 112p Positive electrode tab, 114 Positive electrode active material layer, 120 Negative electrode, 122 Negative electrode current collector foil, 122n Negative electrode tab, 130 Separator, 200 Cell case, 210 Case body, 220 Lid, 300 External terminal, 400 Connecting member, 410 Current collector tab, 420 Sub-tab, 430 Connecting pin, 500 Insulating member, 510 Upper insulating portion, 520 Lower insulating portion, 530 Insulator, 540 Insulating plate.

Claims (5)

a winding step of winding the positive electrode and the negative electrode with a separator interposed therebetween to form a wound body;
a compressing step of compressing the wound body from both sides in the radial direction of the wound body to form a compressed wound body;
a cutting step of cutting the compressed wound body by moving a cutting member from the inside to the outside of the compressed wound body along an orthogonal direction that is orthogonal to both the direction in which the wound body is compressed in the compression step and the central axis of the wound body. The method for manufacturing an electrode assembly described in claim 1, wherein in the winding process, the positive electrode, the negative electrode, and the separator are wound while making slits at predetermined positions in at least one of the positive electrode, the negative electrode, and the separator, thereby forming a wound body having slits formed in the radial direction at the portion of the compressed wound body that will be cut in the cutting process. The method for manufacturing an electrode assembly described in claim 1, wherein, in the cutting step, the compressed wound body is cut with the cutting member while collecting dust on the outside of the compressed wound body in the orthogonal direction. The method for manufacturing an electrode assembly described in claim 1, wherein in the cutting step, the cutting member is moved along the orthogonal direction, and the compressed wound body is expanded from the inside of the compressed wound body in a direction opposite to the direction in which the wound body is compressed in the compression step. The method for manufacturing an electrode assembly according to claim 1, wherein in the compression step, a portion of the compressed wound body to be cut in the cutting step is pressed from the inside of the compressed wound body, thereby forming an outward recess in the orthogonal direction in advance in the portion to be cut.