KR20220017669A - Pouch-type Battery Cell and Method for Manufacturing the Same - Google Patents

Abstract

The present invention relates to a pouch-type battery cell including: an electrode assembly; a battery case having an accommodating unit for accommodating the electrode assembly, and a gas collecting unit; and an opening and closing unit attached to the gas collecting unit and provided to discharge gas inside the battery case, and a method for manufacturing the same, wherein the outer surface of the gas collecting unit can be prevented from being contaminated by an electrolyte during a degassing process.

Description

Pouch-type Battery Cell and Method for Manufacturing the Pouch-Type Battery Cell {Pouch-type Battery Cell and Method for Manufacturing the Same}

The present invention relates to a pouch-type battery cell and a method for manufacturing the pouch-type battery cell, and specifically, to a pouch-type battery cell capable of discharging internal gas using a gas collecting unit attached to a battery case and a method for manufacturing the same will be.

Lithium secondary batteries that can be charged and discharged are widely used as an energy source for wireless mobile devices or wearable devices worn on the body, as well as existing gasoline and diesel vehicles that cause air pollution. It is also used as an energy source for electric vehicles, hybrid electric vehicles, etc.

The lithium secondary battery can be divided into a prismatic battery cell including a metal can-type case, a cylindrical battery cell, and a pouch-type battery cell including a case molded from a laminate sheet, among which, shape deformation is easy, storage and Due to the advantage of increasing the energy density during stacking, pouch-type battery cells are often used.

A general method for manufacturing a pouch-type battery cell includes a packaging process for accommodating an electrode assembly in a pouch together with an electrolyte, an activation process, a degassing process, and an aging process for aging the packaged battery cell for a certain time. In some cases, the activation process and the degassing process may be performed two or more times.

In order to perform the degassing process, when a part of the battery cell placed in the vacuum chamber is cut and the inside of the vacuum chamber is depressurized, the gas inside the battery cell is discharged into the vacuum chamber. In order to perform the degassing process using the vacuum chamber as described above, the entire inner space of the vacuum chamber must be reduced to a predetermined vacuum pressure, but such a process requires high cost.

As another example of the degassing process, a gas outlet may be made in the battery cell using a knife or the like, a vacuum pad connected to a vacuum line may be attached to the gas outlet, and gas may be removed using vacuum pressure.

However, when using such a degassing process, there is a problem in that the gas present in the battery cell is not completely discharged as the gas discharge passage of the battery cell is narrowed due to the instantaneous vacuum pressure.

In addition, in the absence of a separate gas collecting unit, since the upper and lower portions of the pouch-type battery case are more closely contacted by decompression, it is difficult to secure a passage through which the gas moves from the electrode assembly accommodating unit to the vacuum pad.

Accordingly, Patent Document 1 discloses a pouch including a first accommodating part in which an electrode assembly is accommodated and a second accommodating part in which the gas generated in the first accommodating part is collected, and a vacuum pump for generating vacuum pressure, a vacuum pressure Disclosed is a gas removal device comprising a buffer tank maintaining constant, a throttle valve for supplying by adjusting the vacuum pressure, a vacuum pad for sucking gas and electrolyte from the pouch, and a controller for controlling the opening amount of the vacuum gauge and the throttle valve ..

The Patent Document 1 discloses a function of sucking the gas collected in the second accommodating part by the vacuum pressure applied to the pouch and at the same time sucking the electrolyte solution over-injected into the first accommodating part as well. Electrolyte is not prevented from being discharged.

Patent Document 2 is a first degassing step, in which a first vacuum pad and a second vacuum pad are respectively disposed on one surface and the other surface of a pouch extension part, a gas hole is drilled in the extension part, and then the first vacuum pad and the second vacuum pad A step of vacuuming the internal gas of the secondary battery by using a vacuum pad and discharging it to the outside begins.

As in Patent Document 2, when vacuum is sucked into the vacuum pad through the gas hole formed in the extension part, there is a problem that the inner space of the vacuum pad may be contaminated with the electrolyte.

Therefore, in the degassing process of the pouch-type battery cell, the need for a technology that can prevent the electrolyte solution in the electrode assembly receiving part from being discharged together with the gas, and also preventing the internal space of the vacuum pad from being contaminated with the electrolyte solution. the situation is high.

Korean Patent Publication No. 1698488 (2017.01.16) Korean Patent Publication No. 1748362 (2017.06.12)

The present invention is to solve the above problems, and in the process of discharging the internal gas of the pouch-type battery cell, minimizes the discharge of the electrolyte together with the gas, and prevents the part from which the gas is discharged from being contaminated by the electrolyte An object of the present invention is to provide a pouch-type battery cell that can be used and a method for manufacturing the pouch-type battery cell.

The pouch-type battery cell according to the present invention for achieving this object is attached to an electrode assembly, a battery case having a housing and a gas collecting part for accommodating the electrode assembly, and the gas collecting part, and is attached to the inside of the battery case It may include an opening/closing part for discharging gas.

In the pouch-type battery cell according to the present invention, the battery case includes a first case and a second case that are heat-sealed to each other on the outer periphery, and the first case and the second case are gas formed in the same shape at the same location. A collecting unit may be formed.

In the pouch-type battery cell according to the present invention, the gas collecting part may be formed in a stepped structure protruding in two stages.

In the pouch-type battery cell according to the present invention, the gas collecting part may be formed in a structure protruding in a trapezoidal shape in which the width becomes narrower as the distance from the receiving part increases.

In the pouch-type battery cell according to the present invention, the opening/closing part includes a coupling part coupled to the gas collection part of the battery case, a gas exhaust part extending upward from the coupling part, and a stopper located at an inner end of the gas exhaust part may include wealth.

In the pouch-type battery cell according to the present invention, the opening and closing part may be composed of a first polymer resin layer, a metal layer, and a second polymer resin layer.

In the pouch-type battery cell according to the present invention, the first polymer resin layer and the second polymer resin layer may be polypropylene, and the metal layer may be aluminum.

In the pouch-type battery cell according to the present invention, the coupling part may be coupled in a form inserted inside the gas collecting part.

In the pouch-type battery cell according to the present invention, when a vacuum hose is inserted into the gas exhaust unit, the stopper may be opened and gas may be discharged.

The present invention also provides a method for manufacturing the pouch-type battery cell, specifically, (a) manufacturing a first case and a second case by molding a receiving part and a gas collecting part on a laminate sheet, (b) ) coupling the opening and closing part to the gas collecting part, (c) accommodating the electrode assembly in the accommodating part and sealing the outer periphery of the first case and the second case to manufacture a pouch-type battery cell, (d) It may include activating the pouch-type battery cell, and (e) discharging the gas inside the pouch-type battery cell.

In the method of manufacturing a pouch-type battery cell according to the present invention, step (e) may proceed as a process in which a gas is discharged while the stopper is opened when a vacuum hose is inserted into the opening and closing part.

In the method for manufacturing a pouch-type battery cell according to the present invention, the gas collecting part may be formed in the same shape at a position where the first case and the second case face each other.

As described above, the pouch-type battery cell according to the present invention includes a battery case in which a gas collecting unit capable of accommodating gas is formed adjacent to a receiving unit accommodating the electrode assembly, and the gas generated in the receiving unit is It can be easily moved to the gas collecting unit.

In addition, since the gas collection unit is formed in a shape protruding to the outside, a large amount of gas can be accommodated in the gas collection unit until the degassing process is performed.

The opening/closing part included in the pouch-type battery cell may block the inflow of external substances in a closed state, and may be opened when a vacuum hose is inserted to discharge gas.

Since the opening/closing part includes a polymer resin layer, it can be attached to the inner surface of the battery case, and a metal layer is disposed between the polymer resin layers, so that an external material can be blocked from flowing into the pouch-type battery cell.

In addition, since the vacuum hose is directly inserted into the gas collecting part, it is possible to prevent the problem of the vacuum being released from the gas discharge passage.

1 is a perspective view of a pouch-type battery cell according to an embodiment.
2 is a perspective view of a pouch-type battery cell according to another embodiment.
3 is a side view of the pouch-type battery cells shown in FIGS. 1 and 2 .
4 is a perspective view of an opening and closing part according to the present invention.
5 is a vertical cross-sectional view illustrating a process in which the opening/closing part of FIG. 4 is opened.
6 is a vertical cross-sectional view illustrating a process in which the opening/closing unit attached to the gas collecting unit is opened.

Hereinafter, embodiments in which those of ordinary skill in the art to which the present invention pertains can easily practice the present invention will be described in detail with reference to the accompanying drawings. However, in the detailed description of the principle of operation of the preferred embodiment of the present invention, if it is determined that a detailed description of a related well-known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

In addition, the same reference numerals are used throughout the drawings for parts having similar functions and functions. Throughout the specification, when it is said that a certain part is connected to another part, it includes not only a case in which it is directly connected, but also a case in which it is indirectly connected with another element interposed therebetween. In addition, the inclusion of any component does not exclude other components unless otherwise stated, but means that other components may be further included.

In addition, descriptions that limit or add elements may be applied to all inventions unless there are special limitations, and are not limited to specific inventions.

Also, throughout the description and claims of the present application, the singular includes the plural unless otherwise indicated.

Also, throughout the description and claims herein, "or" is intended to include "and" unless stated otherwise. Therefore, "comprising A or B" means all three cases including A, including B, or including A and B.

In addition, all numerical ranges include the values at both ends and all intermediate values therebetween, unless expressly stated otherwise.

The present invention will be described along with detailed examples according to the drawings.

1 is a perspective view of a pouch-type battery cell according to an embodiment.

Referring to FIG. 1 , the pouch-type battery cell according to the present invention is attached to a battery case 110 in which an accommodating part 120 for accommodating an electrode assembly and a gas collecting part 130 are formed, and a gas collecting part 130 . and includes an opening/closing unit 140 for discharging gas inside the battery case.

Although the electrode assembly shows a bidirectional electrode assembly in which the electrode lead 101 protrudes in opposite directions, a unidirectional electrode assembly in which a positive electrode lead and a negative electrode lead protrude together in one direction can be used.

In one preferred example, the battery case may be made of a laminate sheet in which an outer resin layer, a metal layer having air and moisture barrier properties, and an inner resin layer having heat sealing properties are laminated.

Since the outer resin layer must have excellent resistance to the external environment, tensile strength and weather resistance above a predetermined level are required. For example, the outer resin layer may include polyethylene naphthalate (PEN), polyethylene terephthalate (PET), or stretched nylon.

Aluminum (Al) or an aluminum alloy may be used for the metal layer to exhibit a function of improving the strength of the battery case in addition to the function of preventing the inflow of foreign substances such as gas and moisture or the leakage of the electrolyte.

The inner resin layer has heat-sealing properties, has low hygroscopicity to the electrolyte, and a polymer resin that does not expand or erode by the electrolyte may be used. For example, the inner resin layer may be formed of a non-stretched polypropylene film (CPP).

The battery case 110 includes a first case 111 and a second case 112 that are heat-sealed to each other on the outer periphery, and the first case 111 and the second case 112 have the same shape at the same location. A gas collection unit 130 made of is formed.

In a lithium secondary battery, gas is generated due to a side reaction between the electrode assembly and the electrolyte during charging and discharging, and the battery case expands. This may cause a shape change of the battery cell and affect the safety of the battery cell. Therefore, the process of discharging the gas is performed before the assembly of the battery cell is completed.

However, before the gas is discharged, a space for accommodating the gas in the battery case is required. Accordingly, the present invention includes the gas collecting unit 130 formed in a shape protruding outward from the battery case (110).

Accordingly, a sufficient space for accommodating the gas may be secured between the first case 111 and the second case 112 .

In addition, in order for the gas formed in the accommodating part 120 to easily move to the gas collecting part 130 , it is preferable to form a close distance between the accommodating part 120 and the gas collecting part 130 . The portion 130 may be formed at positions spaced apart by the width of the sealing portion in consideration of the width of the sealing portion formed around the accommodating portion 120 .

In one specific example, the gas collecting unit 130 shown in FIG. 1 is formed in a stepped structure protruding in two stages. 1 illustrates a protruding shape in a planar rectangular shape as the step structure, but is not limited thereto, and the step structure may be a round, oval, or polygonal protruding shape in plan view, or, 1st and 2nd steps The shape of the protrusion structure of the stage may be formed in a different shape.

In addition, since the opening/closing unit 140 is attached to the protrusion protruding outward from the gas collection unit 130 having a two-step stepped structure, when a vacuum hose is inserted into the opening/closing unit 140 to remove gas, A vacuum hose can be inserted to some depth. Accordingly, it is possible to prevent the gas collecting unit from being contaminated by the electrolyte when the gas is discharged.

2 is a perspective view of a pouch-type battery cell according to another embodiment.

Referring to FIG. 2 , the pouch-type battery cell is attached to a battery case 210 in which an accommodating part 220 for accommodating an electrode assembly and a gas collecting part 230 are formed, and a gas collecting part 230 , and the battery It includes an opening/closing unit 240 for discharging gas inside the case.

The gas collection unit 230 has a structure in which a trapezoidal shape that becomes narrower as it moves away from the receiving unit 220 protrudes.

In this way, when the gas collecting unit 230 having a wide width adjacent to the receiving unit 220 is used, it is possible to secure a wide passage for the gas generated in the receiving unit 220 to move to the gas collecting unit 230 . There are advantages that can be

The opening/closing unit 240 may be disposed at the center of the trapezoidal plane of the gas collecting unit 230 , and the gas collected in the gas collecting unit may be discharged by vacuum decompression while a vacuum hose is inserted into the opening/closing unit.

In the pouch-type battery cell shown in FIG. 2 , the description of the electrode assembly and the battery case is omitted because the contents described in the description of FIG. 1 can be equally applied.

3 is a side view of the pouch-type battery cells shown in FIGS. 1 and 2 .

Referring to FIG. 3 , (a) is a side view of the pouch-type battery cell of FIG. 1 , and (b) is a side view of the pouch-type battery cell of FIG. 2 .

3 (a) and (b) show the first case (111, 211) and the second case (112, 212), respectively, the gas collecting unit (130, 230) is formed, each of the gas collecting unit (130, The state in which the opening and closing parts 140 and 240 are attached to the 230 is shown.

However, it goes without saying that the opening/closing units 140 and 240 may be attached to only one of the first cases 111 and 211 and the second cases 112 and 212 .

4 is a perspective view of the opening/closing unit according to the present invention, and FIG. 5 is a vertical cross-sectional view illustrating a process in which the opening/closing unit of FIG. 4 is opened.

4 and 5 , the opening/closing unit 140 is the opening/closing unit 140 shown in FIG. 1 , and the same reference numerals are used. The opening/closing unit 140 includes a coupling unit 141 coupled to the gas collecting unit of the battery case, a gas exhaust unit 142 extending upwardly from the coupling unit 141 , and a stopper located at the inner end of the gas exhaust unit 142 . part 143 .

The gas exhaust part 142 has an outer end open, and a stopper 143 is disposed on the inner end. The entire opening/closing part 140 has a structure in which a first polymer resin layer 141a, a metal layer 141b, and a second polymer resin layer 141c are sequentially stacked.

A first polymer resin layer 141a or a second polymer resin layer 141c is disposed on each of both sides of the metal layer 141b, and the first polymer resin layer 141a and the second polymer resin layer 141c are thermally meltable. It may be made of a polymer resin. Accordingly, in order to attach the opening/closing unit 140 to the battery case, a method of heating the contact surface of the coupling unit and the gas collecting unit may be used in a state in which the coupling unit 141 is disposed inside the gas collecting unit.

That is, the first polymer resin layer 141a may be thermally fused with the internal resin layer of the gas collection unit.

The first polymer resin layer and the second polymer resin layer may be, for example, at least one selected from the group consisting of polypropylene, polyethylene, and polyvinyl chloride to be coupled to the gas collection unit, in detail , may be polypropylene, and more specifically, may be rigid polypropylene.

The metal layer 141b is a part for preventing moisture, etc. from penetrating into the battery case and securing the rigidity of the battery case, and for example, aluminum having excellent formability may be used.

Referring to FIG. 5 , the stopper 143 of the opening/closing unit 140 includes a non-deformable fixed portion 143a and a deformable portion 143b, and has an arch structure convex downward as a whole.

Since the deformable part 143b is disposed inside the fixed part 143a, when gas is generated inside the battery cell and the internal pressure of the gas collecting part increases, the deformable part ( 143b) maintains a state in contact with the fixing part 143a as shown in (a) of FIG. 5 . That is, the opening/closing part is in a closed state.

However, in order to discharge the gas inside the battery cell as shown in (b) of FIG. 5 , the vacuum hose 148 is inserted into the opening/closing unit 140 and passing through the gas exhaust unit 142 , while the deformable part of the stopper 143 ( 143b) may be inserted into the gas collecting unit while pushing. At this time, since the inside of the gas collection unit is in a state of being in communication with the outside through the vacuum hose 148 , gas may be discharged through the vacuum hose 148 .

6 is a vertical cross-sectional view illustrating a process in which the opening/closing unit attached to the gas collecting unit is opened.

FIG. 6 illustrates a state in which an opening/closing unit is added only to the gas collecting unit 230 formed in the first case 211 .

The opening and closing part is a state in which the internal resin layer of the first case 211 and the coupling part 241 are combined, and a through hole is formed at the position where the opening and closing part is to be disposed in the step before thermal fusion sealing of the outer periphery of the battery case, and the opening and closing part is disposed It is preferable to do

Alternatively, the opening/closing unit may be formed of a heat-meltable resin with the first polymer resin layer and the second polymer resin layer as the center of the metal layer, and unlike that shown in FIG. 6, the opening/closing unit may be combined with the external resin layer of the first case. can

As shown in (a), before the vacuum hose 248 is inserted, the stopper 243 maintains a closed state, thereby maintaining the sealed state of the battery cell, but as shown in (b), as the vacuum hose 248 is inserted, the stopper ( Since the 243 is pushed in, the stopper 243 is opened.

The open area of the stopper 243 has a size corresponding to the diameter of the vacuum hose 248 so that the vacuum state inside the battery cell can be maintained with the vacuum hose inserted and the gas can be discharged only through the vacuum hose. It is preferable to be

In this way, when the vacuum hose is inserted to discharge gas, since the vacuum hose can be inserted into the gas collection unit, even if the electrolyte is discharged along with the gas discharge, the electrolyte does not stick to the outer surface of the gas collection unit do.

Therefore, in the case of performing a degassing process using a conventional vacuum pad, when the vacuum pad is removed from the gas collecting part, the outer surface of the gas collecting part is contaminated by the residual electrolyte, and the residual electrolyte is used in the subsequent process Although there is a problem that contamination may be spread by the equipment being used, in the present invention, it is possible to prevent the electrolyte from being deposited on the outer surface of the gas collection unit, thereby preventing the spread of contamination of the electrolyte.

In order to manufacture the pouch-type battery cell according to the present invention, (a) manufacturing the first case and the second case by molding the receiving part and the gas collecting part on a laminate sheet, (b) coupling the opening and closing parts to the gas collecting part (c) accommodating the electrode assembly in the accommodating part and sealing the outer periphery of the first case and the second case to manufacture a pouch-type battery cell, (d) activating the pouch-type battery cell , and (e) discharging the gas inside the pouch-type battery cell.

The opening and closing part includes a coupling part coupled to the gas collection part of the battery case, a gas exhaust part extending upward from the coupling part, and a stopper located at an inner end of the gas exhaust part.

In the step (b), the gas may be coupled such that the coupling part of the opening and closing part is attached to the inner surface of the gas collection part.

In step (e), when a vacuum hose is inserted into the opening/closing part, the stopper may be opened and the gas may be discharged.

The gas collecting part may be formed in the same shape at a position where the first case and the second case face each other. Accordingly, a gas collecting unit having a size that is the sum of the internal space of the gas collecting unit formed in the first case and the gas collecting unit formed in the second case is formed. You can get enough space.

In addition, by forming the gas collecting unit adjacent to the receiving unit in which the electrode assembly is accommodated, a passage through which the gas formed in the receiving unit can smoothly move to the gas collecting unit may be secured.

Those of ordinary skill in the art to which the present invention pertains will be able to perform various applications and modifications within the scope of the present invention based on the above contents.

101: electrode lead
110, 210: battery case
111, 211: first case
112, 212: second case
120, 220: storage unit
130, 230: gas collection unit
140, 240: opening and closing part
141, 241: coupling part
142, 242: gas exhaust part
143, 243: stopper
141a: first polymer resin layer
141b: metal layer
141c: second polymer resin layer
143a: fixed part
143b: deformation part
148, 248: vacuum hose

Claims (12)

electrode assembly;
a battery case in which an accommodating part for accommodating the electrode assembly and a gas collecting part are formed; and
an opening and closing part attached to the gas collection part and for discharging the gas inside the battery case;
A pouch-type battery cell comprising a. According to claim 1, wherein the battery case comprises a first case and a second case heat-sealed to each other at the outer periphery,
The first case and the second case are pouch-type battery cells in which a gas collecting part of the same shape is formed at the same location. The pouch-type battery cell according to claim 2, wherein the gas collecting part has a stepped structure protruding in two stages. The pouch-type battery cell according to claim 2, wherein the gas collecting part has a structure protruding in a trapezoidal shape whose width becomes narrower as the distance from the accommodating part increases. The method of claim 1, wherein the opening and closing portion,
a coupling unit coupled to the gas collecting unit of the battery case;
a gas exhaust portion extending upward from the coupling portion; and
a stopper located at the inner end of the gas exhaust unit;
A pouch-type battery cell comprising a. The pouch-type battery cell according to claim 5, wherein the opening/closing part comprises a first polymer resin layer, a metal layer, and a second polymer resin layer. The pouch-type battery cell according to claim 6, wherein the first polymer resin layer and the second polymer resin layer are made of polypropylene, and the metal layer is made of aluminum. The pouch-type battery cell according to claim 5, wherein the coupling part is inserted into the gas collecting part. The pouch-type battery cell according to claim 5, wherein when the vacuum hose is inserted into the gas exhaust part, the gas is discharged while the stopper is opened. As a method for manufacturing a pouch-type battery cell according to any one of claims 1 to 9,
(a) manufacturing the first case and the second case by molding the receiving part and the gas collecting part on the laminate sheet;
(b) coupling an opening and closing part to the gas collection part;
(c) accommodating the electrode assembly in the accommodating part and sealing the outer periphery of the first case and the second case to manufacture a pouch-type battery cell;
(d) activating the pouch-type battery cell; and
(e) discharging the gas inside the pouch-type battery cell;
A pouch-type battery cell manufacturing method comprising a. 11. The method of claim 10, wherein in step (e), when a vacuum hose is inserted into the opening and closing part, the stopper is opened and the gas is discharged. The method of claim 10 , wherein the gas collecting part is formed in the same shape at a position where the first case and the second case face each other.

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