KR20230127912A - Pouch folding device for secondary battery and secondary battery - Google Patents

Abstract

The present invention relates to a pouch folding device for secondary batteries and a secondary battery, and the pouch folding device for secondary batteries according to the present invention folds a pouch including a body accommodating an electrode assembly and a sealing portion formed along an edge of the body. A device comprising: a side folding unit for side folding the sealing unit of the pouch toward the body; and a corner folding roller including a corner folding roller for corner folding toward the body by pressing a corner portion of the side-folded sealing unit, wherein the corner folding roller includes a flat surface and an inclined surface formed on a pressing surface, and the pressing In the corner folding roller, the inclined surface is positioned closer to the body than the flat surface.

Description

Pouch folding device for secondary battery and secondary battery {Pouch folding device for secondary battery and secondary battery}

The present invention relates to a pouch folding device for a secondary battery and a secondary battery.

Secondary batteries, unlike primary batteries, can be recharged, and have recently been extensively researched and developed due to their small size and high capacity. As technology development and demand for mobile devices increase, demand for secondary batteries as an energy source is rapidly increasing.

Secondary batteries are classified into coin-type batteries, cylindrical batteries, prismatic batteries, and pouch-type batteries according to the shape of a battery case. In a secondary battery, an electrode assembly installed inside a battery case is a power generating device capable of charging and discharging, consisting of a laminated structure of electrodes and separators.

The electrode assembly consists of unit cells in which at least one electrode and at least one separator are stacked in a jelly-roll type wound with a separator interposed between a sheet-type positive electrode and a negative electrode coated with an active material. It can be roughly classified into a stack type in which the cells are sequentially stacked and a stack/fold type in which unit cells are wound with a long separation film.

When manufacturing a secondary battery, a process of folding a corner portion of a pouch accommodating an electrode assembly is performed. In the process of folding the corners of the pouch, a problem arises in the insulation quality when the pouch is pressed with a tool.

More specifically, the pouch has a cup portion, which is a body in which the electrode assembly is accommodated, and a sealing portion formed along an edge of the cup portion. Here, the sealing part has a flat shape, and the cup part has a three-dimensional shape convex with respect to the sealing part rather than being flat in which the electrode assembly is accommodated.

In order to fold the pouch a lot, a mechanism is attached in the direction of the cup portion, but when the cup portion is an unsealed portion and is pressed with a flat mechanism, it is damaged and a risk occurs in insulation quality.

One aspect of the present invention is to provide a pouch folding device for a secondary battery and a secondary battery capable of securing insulation quality during pouch folding.

A pouch folding device for a secondary battery according to an embodiment of the present invention is a pouch folding device for a secondary battery that folds a pouch including a body in which an electrode assembly is accommodated and a sealing portion formed along an edge of the body, wherein the sealing portion of the pouch is directed toward the body. a side folding unit for side folding; and a corner folding roller including a corner folding roller for corner folding toward the body by pressing a corner portion of the side-folded sealing unit, wherein the corner folding roller includes a flat surface and an inclined surface formed on a pressing surface, and the pressing In the corner folding roller, the inclined surface may be positioned closer to the body than the flat surface.

Meanwhile, the secondary battery according to an embodiment of the present invention may be a secondary battery manufactured through a pouch folding device for a secondary battery according to an embodiment of the present invention.

According to the present invention, by folding the corner of the pouch using a corner folding roller having an inclined surface, it is possible to prevent an insulation quality risk from occurring in an uneven pouch portion where an electrode assembly is accommodated. That is, as the flat surface of the corner folding roller with a constant diameter presses the sealing area of the flat pouch, and the inclined surface presses the non-sealing area of the non-flat pouch in which the electrode assembly is accommodated, the non-sealing area of the pouch is damaged. This can be prevented and the insulation quality can be secured.

1 is a plan view exemplarily illustrating a process of accommodating an electrode assembly in a pouch before folding the pouch.
2 is a front view illustrating a process of side-folding a pouch through a side-folding unit in a pouch folding device for a secondary battery according to an embodiment of the present invention.
3 is a perspective view showing a side-folded state of a pouch through a pouch folding device for a secondary battery according to an embodiment of the present invention.
4 is a perspective view showing a corner folding part in a pouch folding device for a secondary battery according to an embodiment of the present invention.
5 is a perspective view illustrating a folding roller and a roller moving unit in a pouch folding device for a secondary battery according to an embodiment of the present invention.
6 is a front view showing a corner folding roller in a pouch folding device for a secondary battery according to an embodiment of the present invention.
7 is a perspective view illustrating a concept of corner folding in a pouch folding device for a secondary battery according to an embodiment of the present invention.
8 is a perspective view showing a main part of a corner-folded pouch in a pouch folding device for a secondary battery according to an embodiment of the present invention.

Objects, specific advantages and novel features of the present invention will become more apparent from the following detailed description and preferred embodiments taken in conjunction with the accompanying drawings. In adding reference numerals to components of each drawing in this specification, it should be noted that the same components have the same numbers as much as possible, even if they are displayed on different drawings. In addition, the present invention may be embodied in many different forms and is not limited to the embodiments described herein. In addition, in describing the present invention, detailed descriptions of related known technologies that may unnecessarily obscure the subject matter of the present invention will be omitted.

1 is a plan view exemplarily illustrating a process in which an electrode assembly is accommodated in a pouch before folding the pouch, and FIG. 2 is a process in which the pouch is side-folded through a side-folding unit in a pouch folding device for a secondary battery according to an embodiment of the present invention. Figure 3 is a perspective view showing a side-folding state of the pouch through the pouch folding device for secondary batteries according to an embodiment of the present invention, Figure 4 is a corner in the pouch folding device for secondary batteries according to an embodiment of the present invention It is a perspective view showing the folding part.

1 to 4, the pouch folding device for secondary batteries according to an embodiment of the present invention folds the pouch 10 including the body 12 and the sealing part 13 in which the electrode assembly 20 is accommodated. As a battery pouch folding device, a side folding portion (SR) for side-folding the sealing portion (13) of the pouch (10) toward the body (12), and pressing the corner portion (14) in the side-folded sealing portion (13) and a corner folding portion CR including a corner folding roller 110 for corner folding in the direction of the body 12.

In more detail, referring to FIG. 1 , a secondary battery 1 applied to a pouch folding device for secondary batteries according to an embodiment of the present invention includes an electrode assembly 20 and an electrode assembly 20 in an internal accommodating part 11. It includes a pouch 10 for accommodating. In addition, the secondary battery 1 may further include an electrode lead 30 connected to the electrode assembly 20 and extended to the outside of the pouch 10 . The electrode lead 30 may extend in the longitudinal direction of the secondary battery 1 . Here, the longitudinal direction of the secondary battery 1 may be, for example, the Y-axis direction when referring to FIG. 1 .

The pouch 10 includes a body 12 accommodating the electrode assembly 20 and a sealing portion 13 formed along an edge of the body 12 .

Here, the sealing part 13 is formed in a flat flat shape, and the body 12 is formed in a convex three-dimensional shape with respect to the sealing part 13 in which the electrode assembly 20 is accommodated.

The electrode assembly 20 may be formed in an aggregated form by alternately stacking electrodes and separators. Here, the electrode assembly 20 is a power generating element capable of charging and discharging.

The electrode includes an anode and a cathode, and in the electrode assembly 20, an anode, a separator, and a cathode may be alternately stacked. Here, the separator separates the positive electrode and the negative electrode to electrically insulate them.

The cathode may include a cathode current collector and a cathode active material laminated on the cathode current collector.

The cathode current collector may be made of an aluminum foil.

The cathode active material may be formed of lithium manganese oxide, lithium cobalt oxide, lithium nickel oxide, lithium iron phosphate, or a compound or mixture containing at least one of these.

The negative electrode may include a negative electrode current collector and a negative electrode active material laminated on the negative electrode current collector.

The negative electrode current collector may be formed of, for example, a foil made of a copper (Cu) material.

The negative electrode active material may be a compound or mixture including a graphite-based material.

The separator is made of an insulating material and electrically insulates between the anode and the cathode. Here, the separator may be formed of a polyolefin-based resin film such as polyethylene and polypropylene having microporosity.

Referring to FIGS. 2 and 3 , the side folding part SR may side-fold the sealing part 13 of the pouch 10 toward the body 12 .

The side folding parts SR may fold the sealing parts 13 located on both sides of the pouch 10 toward the body 12 . Here, the side folding part SR may side-fold the sealing parts 13 located on both sides of the pouch 10 in the width direction of the pouch 10 toward the body 12 . At this time, the width direction of the pouch 10 may be a lateral direction with respect to the longitudinal direction of the pouch 10 in which the electrode lead 30 connected to the electrode assembly 20 extends. That is, when referring to FIG. 3 , the width direction of the pouch 10 may be the X-axis direction. Also, the width direction of the pouch 10 may be the same as the width direction of the secondary battery 1 .

In addition, the side folding part SR may fold both sides of the sealing part 13 of the pouch 10 at a right angle.

In addition, the side folding part SR may be composed of, for example, a side folding roller. At this time, both sides of the sealing portion 13 of the pouch 10 may be pressed and folded through the side folding rollers. However, in the pouch folding device for a secondary battery according to an embodiment of the present invention, the side folding unit (SR) is not necessarily limited to a side folding roller, and various folding mechanisms may be used. For example, a plurality of folding blocks may be crossed with each other The sealing portion 13 of the pouch 10 may be pressed and folded.

5 is a perspective view showing a folding roller and a roller moving part in a pouch folding device for a secondary battery according to an embodiment of the present invention, and FIG. 6 is a front view showing a corner folding roller in a pouch folding device for a secondary battery according to an embodiment of the present invention. 7 is a perspective view showing the concept of corner folding in the pouch folding device for secondary batteries according to an embodiment of the present invention, and FIG. 8 shows a corner-folded pouch in the pouch folding device for secondary batteries according to an embodiment of the present invention. It is a perspective view of the waist.

4 to 8, the corner folding part CR includes a corner folding roller 110 that presses the corner part 14 from the side-folded sealing part 13 and folds the corner toward the body 12. can do.

Referring to FIGS. 4 and 5 , the corner folding part CR moves the corner folding roller 110 from the outer edge of the pouch 10 toward the center, and the corner part 14 of the side-folded sealing part 13 Corner folding may be performed to closely adhere to the outer surface of the pouch 10 . In addition, the corner folding unit CR moves the corner folding roller 110 in the X-axis direction, which is the width direction of the pouch 10, after the pouch 10 is positioned parallel to the XY plane, thereby sealing the sealing unit 13. Corner folding is possible.

Referring to FIGS. 6 and 7 , the corner folding roller 110 may include a flat surface 112 and an inclined surface 111 formed on a pressure surface 113 . Here, the inclined surface 111 may be formed at an end of the corner folding roller 110 . That is, the outer circumferential portion of the corner folding roller 110 that presses the pouch 10 may include a flat surface 112 having a constant diameter and an inclined surface 111 having a smaller diameter toward the end. Also, when pressurized, the inclined surface 111 of the corner folding roller 110 may be positioned closer to the body 12 than the flat surface 112 .

At this time, when the corner part 14 of the side-folded sealing part 13 is pressed through the corner folding roller 110, the inclined surface 111 is located at the corner part 14 that is folded in contact with the body 12. It can be. More specifically, the flat surface 112 presses the first portion 14a at the corner portion 14 of the pouch 10, and the inclined surface 111 presses the second portion (14a) at the corner portion 14 of the pouch 10 ( 14b) may be pressed, and the corner portion 14 of the pouch 10 may be folded. That is, the corner folding part CR presses the corner part 14 of the sealing part 13 and presses the flat surface 112 of the corner folding roller 110 at the corner part 14 during corner folding. Portion 14a is folded in contact with portion 13a located in the longitudinal direction of pouch 10 at sealing portion 13, and pressed against inclined surface 111 of corner folding roller 110 at corner portion 14. The second part 14b to be can be folded to come into contact with the body 12.

At this time, the first part 14a is folded at the corner part 14 by the flat surface 112, the sealing area of the flat pouch 10 is pressed, and the corner part 14 is pressed by the inclined surface 111. ), the second part 14b is folded and the electrode assembly 20 is accommodated so that the non-sealing area of the non-flat pouch 10 can be pressed. Here, the sealing area of the pouch 10 to be pressed is a portion of the sealing portion 13 extending in the longitudinal direction of the secondary battery 1 from the sealing portion 13, and the non-sealing area of the pouch 10 is the pouch 10 It may be a part of the body 12 of. At this time, the portion of the body 12 of the pouch 10 pressed against the inclined surface 111 of the corner folding roller 110 may be, for example, a terrace portion. Here, the terrace portion may be a portion of the body 12 that is not in contact with the electrode assembly 20 . That is, it may be a portion of the pouch 10 positioned in an empty space between the end of the electrode assembly 20 and the sealing portion 13 of the pouch 10 in the receiving portion 11 of the pouch 10 . At this time, the terrace portion may form a slope.

In addition, the corner folding roller 110 presses the corner portion 14 of the sealing portion 13 of the side-folded pouch 10, the inclined surface 111 on the side adjacent to the body 12 with respect to the flat surface 112 ) can be located. Here, the inclined surface 111 of the corner folding roller 110 may be formed with a slope in which the width of the end becomes narrower toward the end. At this time, the inclination angle α of the inclined surface 111 may be formed to be, for example, 20 to 50°. Here, the inclination angle α of the inclined surface 111 may be an inclined angle of the inclined surface 111 with respect to a virtual extension line extending from the flat surface 112 .

Therefore, since the inclination angle α of the inclined surface 111 is formed to be 20° or more, the effect on insulation quality can be remarkably improved. That is, when the pressure roller in the form of a flat cylinder without an inclined surface 111 presses the terrace portion, which is the non-sealing area of the non-flat pouch 10, in which the electrode assembly 20 is accommodated, Although the non-sealing area of the pouch 10 may be damaged by the edge of the roller and the insulation quality may be degraded, in the pouch folding device for a secondary battery according to an embodiment of the present invention, the corner folding roller 110 is The inclination angle α is formed at 20° or more, so that when the corner portion 14 of the sealing portion 13 of the pouch 10 is pressed, the terrace portion, which is the non-sealing area of the pouch 10 that is not flat, is formed. It can be pressurized so as not to be damaged, and thus, the non-sealing area of the pouch 10 is prevented from being damaged, so that insulation quality can be secured.

In addition, since the inclination angle α of the inclined surface 111 is formed to be 50° or less, it is possible to adjust the degree of folding the pouch into a desired shape. That is, when the inclination angle α of the inclined surface 111 exceeds 50°, the folding effect may be remarkably small. As a result, when the inclination angle α of the inclined surface 111 exceeds 50 °, the inclined surface 111 cannot press the non-sealing area of the pouch 10 that is not flat, or the pressing force is significantly reduced, so that the pouch ( The corner portion 14 of the sealing portion 13 of 10) is not properly folded, and the non-flat pouch 10 is damaged by the corner between the inclined surface 111 and the flat surface 112. This can lead to deterioration of insulation quality.

Meanwhile, the length L2 of the flat surface 112 may be, for example, 2 mm or more. Accordingly, the length L2 of the flat surface 112 in the corner folding roller 110 is formed to be 2 mm or more, so that the corner folding of the sealing portion 13 of the side-folded pouch 10 may be possible.

Meanwhile, for example, in the corner folding roller 110, the length L1 of the orthogonal projection of the inclined surface 111 may be longer than the length L2 of the flat surface 112. In addition, in the corner folding roller 110, the projection length L1 of the inclined surface 111 may be 400% or less of the length L2 of the flat surface 112.

Meanwhile, the corner folding roller 110 may further include a roller shaft 114. The roller shaft 114 may be configured as a rotation shaft of the corner folding roller 110 .

On the other hand, when corner folding the sealing part 13 of the pouch 10 through the corner folding roller 110, for example, it can be carried out at room temperature, but the method of implementing the pouch folding device for secondary batteries according to an embodiment of the present invention. This is not necessarily limited here.

Meanwhile, in the folding device of the secondary battery pouch 10 according to the embodiment of the present invention, the corner folding unit CR includes the roller moving unit 120, the lower support unit 130, the upper support unit 140, and the support frame 150. may further include.

The roller moving unit 120 may be equipped with a corner folding roller 110 to move the corner folding roller 110 . In addition, the roller moving unit 120 may move the corner folding roller 110 along the X-axis direction from the outer edge of the pouch 10 toward the central portion.

The lower support part 130 may support the lower part of the pouch 10 during corner folding. The lower support part 130 is provided as a plurality of blocks to support the lower end of the body 12 of the pouch 10 .

The upper support part 140 may support the upper part of the pouch 10 during corner folding. When the pouch 10 is pressed through the corner folding roller 110, the upper support 140 may be located on the opposite side between the corner folding roller 110 and the pouch 10. Accordingly, when the pouch 10 is pressed through the corner folding roller 110, the pouch 10 is supported so that a folding operation can be easily performed.

The support frame 150 may support each device of the corner folding unit CR.

5 and 6, the pouch folding device for a secondary battery according to an embodiment of the present invention configured as described above uses a corner folding roller 110 having an inclined surface 111 to form a corner portion 14 of the pouch 10. ), it is possible to prevent an insulation quality risk from occurring in the non-flat portion of the pouch 10 in which the electrode assembly 20 is accommodated. That is, the flat surface 112 of the corner folding roller 110, which has a constant diameter, presses the sealing area of the flat pouch 10, and the inclined surface 111 accommodates the electrode assembly 20 in the non-flat pouch 10. ), it is possible to prevent the non-sealing area of the pouch 10 from being damaged and to secure insulation quality.

Meanwhile, referring to FIGS. 1, 7, and 8 , a secondary battery 1 may be manufactured through a pouch folding device for a secondary battery according to an embodiment of the present invention.

That is, the secondary battery according to the embodiment of the present invention is the secondary battery 1 manufactured through the pouch folding device for the secondary battery according to the above-described embodiment of the present invention.

In the secondary battery 1 , the corner portion 14 of the sealing portion 13 of the pouch 10 is corner-folded toward the body and is provided in a bent state.

The bent corner part 14 includes a first part 14a that is folded by being pressed against the flat surface 112 of the corner folding roller 110 and a second part 14b that is folded by being pressed by the inclined surface 111. .

The first portion 14a forms a flat portion, and the second portion 14b forms an inclined portion inclined with respect to the first portion 14a.

The second portion 14b may be formed with an inclination of 20 to 50° with respect to a virtual extension line of the first portion 14a.

<Production Example>

A pouch folding device for a secondary battery that folds a pouch including a body accommodating an electrode assembly and a sealing portion formed along an edge of the body was manufactured.

The pouch folding device for a secondary battery was manufactured by including a corner folding portion that presses a corner portion of a side-folded sealing portion and folds the corner toward the body.

The corner folding part was composed of a corner folding roller including a flat surface and an inclined surface formed on a pressing surface.

The corner folding roller is manufactured in a form in which an inclined surface can be positioned adjacent to the body of the pouch when pressed.

In addition, referring to FIG. 6 , the corner folding roller has a length L2 of the flat surface 112 of 2 mm and a projection length L1 of the inclined surface 111 of 3.5 mm. And, the inclination angle α of the inclined surface 111 was formed to be 25°.

<Comparative Example>

A pouch folding device for a secondary battery was manufactured in the same manner as in Preparation Example, except that the corner folding rollers formed all of the pressing surfaces as flat surfaces.

<Experimental Example>

IR (resistance) defect rate and IV (voltage) defect rate of the corner folding portion of the pouch in the secondary battery manufactured through the pouch folding device for secondary battery according to Examples and Comparative Examples were measured based on 100 MOhm.

At this time, a secondary battery having a sealing portion having a width of 2 mm in the pouch was corner folded.

manufacturing example comparative example IR defect rate 1.7% 8.2% IV defective rate 0.0% 3.45%

As shown in Table 1, it can be seen that the IR defect rate in Comparative Example was 8.2%, whereas the IR defect rate in Manufacturing Example was significantly reduced to 1.7%.

In addition, it can be seen that the IR defect rate in Comparative Example was 3.45%, whereas the IR defect rate in Manufacturing Example was significantly reduced to 0.0%.

Therefore, it can be seen that the insulation defect rate is significantly reduced in the manufacturing example than in the comparative example.

Although the present invention has been described in detail through specific examples, this is for specifically explaining the present invention, and the present invention is not limited thereto. It will be said that various implementations are possible by those skilled in the art within the technical spirit of the present invention.

In addition, the specific protection scope of the invention will be clarified by the appended claims.

1: secondary battery
10: Pouch
11: receiving part
12: body
13: sealing part
14: corner part
14a: first part
14b: second part
20: electrode assembly
30: electrode lead
110: corner folding roller
111: slope
112: flat surface
113: pressure surface
114: roller axis
120: roller moving unit
130: lower support
140: upper support
150: support frame
SR: side folding part
CR: corner folding part

Claims (13)

A pouch folding device for a secondary battery that folds a pouch including a body accommodating an electrode assembly and a sealing portion formed along an edge of the body,
a side folding unit for side-folding the sealing unit of the pouch toward the body; and
A corner folding portion including a corner folding roller for corner folding toward the body by pressing a corner portion of the side-folded sealing portion;
The corner folding roller includes a flat surface and an inclined surface formed on a pressing surface,
When pressurized, the inclined surface of the corner folding roller is located in a position closer to the body than the flat surface. The method of claim 1,
The side folding unit folds the sealing unit located on both sides of the pouch in the direction of the body. The method of claim 2,
The side folding part folds the sealing part located on both sides of the pouch in the width direction of the pouch in the direction of the body,
A pouch folding device for a secondary battery in which the width direction of the pouch is lateral with respect to the longitudinal direction of the pouch in which the electrode lead connected to the electrode assembly extends. The method of claim 3,
The corner folding unit moves the corner folding roller from the outer edge of the pouch in the direction of the body to the central portion, and brings the corner portion of the side-folded sealing unit in close contact with the outer surface of the pouch. The method of claim 4,
The corner folding part presses the corner part and when the corner is folded,
The first part pressed against the flat surface of the corner folding roller at the corner part is folded so as to come into contact with the part located in the longitudinal direction of the pouch in the sealing part, and pressed against the inclined surface of the corner folding roller at the corner part. The second part is a pouch folding device for a secondary battery that is folded so as to be in contact with the body. The method of claim 1,
The inclined surface is positioned at the end of the corner folding roller pouch folding device for secondary batteries. The method of claim 6,
The inclined surface of the corner folding roller is a pouch folding device for secondary batteries formed with an incline in which the width of the end becomes narrower toward the end. The method of claim 7,
The inclination angle of the inclined surface is a pouch folding device for a secondary battery formed at 20 to 50 °. The method of claim 1,
The corner folding part
A pouch folding device for a secondary battery further comprising a roller moving unit to which the corner folding roller is mounted and moving the corner folding roller. The method of claim 1,
The corner folding part
Pouch folding device for a secondary battery further comprising a lower support for supporting a lower portion of the pouch during corner folding. The method of claim 1,
The corner folding part
Pouch folding device for a secondary battery further comprising an upper support for supporting an upper portion of the pouch during corner folding. A secondary battery manufactured through the pouch folding device for secondary batteries according to any one of claims 1 to 11. The method of claim 12,
The secondary battery is provided in a state where the corner portion of the sealing portion of the pouch is corner-folded toward the body and bent;
The bent corner portion includes a first portion pressed and folded on the flat surface of the corner folding roller and a second portion pressed and folded on the inclined surface,
The secondary battery of claim 1 , wherein the second portion is formed at an angle of 20 to 50° with respect to the extension line of the first portion.

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