CN116529945A

CN116529945A - Battery unit and battery module comprising same

Info

Publication number: CN116529945A
Application number: CN202280007386.1A
Authority: CN
Inventors: 宋大雄; 金橡熏; 姜旻亨; 庾亨均; 林鑂熙; 黄随枝
Original assignee: LG Energy Solution Ltd
Current assignee: LG Energy Solution Ltd
Priority date: 2021-07-06
Filing date: 2022-07-06
Publication date: 2023-08-01

Abstract

A battery cell according to an embodiment of the present invention includes: a battery case in which the electrode assembly is mounted in the receiving part and which includes a sealing part having a structure in which the outer circumference thereof is sealed; an electrode lead electrically connected to an electrode tab included in the electrode assembly and protruding outward from the battery case through the sealing part; and a lead film at a portion corresponding to the sealing portion at the top and/or bottom of the electrode lead, wherein the gas discharge guide portion is inserted into the lead film, the battery case includes a cover portion extending from the sealing portion, and the cover portion is located on the lead film and can protrude outward from the battery case.

Description

Battery unit and battery module comprising same

Technical Field

The present disclosure relates to a battery cell and a battery module including the same, and more particularly, to a battery cell having improved insulation performance and gas discharge performance, and a battery module including the same. The present application claims priority from korean patent application No.10-2021-0088729 filed in korea at 7.6 of 2021 and korean patent application No.10-2022-0081995 filed in korea at 7.4 of 2022, the disclosures of which are incorporated herein by reference.

Background

As the technology development and demand for mobile devices increase, the demand for secondary batteries as an energy source is rapidly increasing. In particular, the secondary battery has been attracting attention not only as an energy source for mobile devices such as mobile phones, digital cameras, notebook computers, and wearable devices, but also as an energy source for power devices such as electric bicycles, electric vehicles, hybrid electric vehicles, and the like.

These secondary batteries are classified into cylindrical batteries and prismatic batteries in which an electrode assembly is included in a cylindrical or prismatic metal can, and pouch-type batteries in which an electrode assembly is included in a pouch-type case of an aluminum laminate sheet, according to the shape of the battery case. Here, the electrode assembly included in the battery case is an electric power element including a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode, and is capable of charge and discharge, and is classified into a roll core type in which a long sheet-type positive electrode and a negative electrode coated with an active material are wound together with the separator interposed therebetween, and a laminate type in which a plurality of positive electrodes and negative electrodes are sequentially laminated with the separator interposed therebetween.

Among them, in particular, pouch-type batteries, in which a laminate-type or laminate/folding-type electrode assembly is included in a pouch-type battery case made of an aluminum laminate sheet, are increasingly used due to low manufacturing costs, light weight, and easy deformation.

Fig. 1 is a top view illustrating a conventional battery cell. Fig. 2 is a cross-sectional view taken along the axis a-a' of fig. 1.

Referring to fig. 1 and 2, the conventional battery cell 10 includes a battery case 20, the battery case 20 having a receiving part 21 in which the electrode assembly 11 is mounted and a sealing part 25 formed by sealing the outer circumference thereof. In addition, the battery cell 10 includes: an electrode lead 30, the electrode lead 30 being electrically connected to an electrode tab 15 included in the electrode assembly 11 and protruding outside the battery case 20 via a sealing part 25; and a lead film 40, the lead film 40 being located between the upper and lower parts of the electrode lead 30 and the sealing part 25.

However, with the recent increase in cell energy density, there are problems in that: the amount of gas generated inside the battery cell also increases. In the case of the conventional battery cell 10, there is no component capable of discharging the gas generated inside the battery cell, and thus, since the gas is generated in long-term storage, the gas may be discharged to rupture the battery case 20. In addition, moisture may penetrate into the battery cells damaged by the exhaust gas, which may cause side reactions, and there are problems in that the battery performance is deteriorated and additional gas is generated. Therefore, there is an increasing need to develop battery cells that improve the external discharge of gases generated inside the battery cells.

Disclosure of Invention

Technical problem

The present disclosure is directed to providing a battery cell having improved insulation performance and gas discharge performance, and a battery module including the same.

The objects to be solved by the present disclosure are not limited to the above-described objects, and objects not mentioned herein can be clearly understood by those skilled in the art from the present specification and drawings.

Technical proposal

In one aspect of the present disclosure, there is provided a battery cell including: a battery case having a receiving part in which the electrode assembly is mounted, and a sealing part formed by sealing the outer circumference thereof; an electrode lead electrically connected to an electrode tab included in the electrode assembly and protruding outside the battery case via the sealing part; and a lead film located at a portion corresponding to the sealing portion in at least one of an upper portion and a lower portion of the electrode lead, wherein a gas discharge guide unit is inserted into the lead film, the battery case includes a cover portion extending from the sealing portion, and the cover portion is located on the lead film and protrudes in an outward direction of the battery case.

The cover part may be located on the gas discharge guide unit.

The length of the cover portion may be equal to or greater than the length of the gas discharge guide unit based on a direction perpendicular to the protruding direction of the electrode lead.

The length of the cover portion may be equal to or less than the length of the lead film based on a direction perpendicular to the protruding direction of the electrode lead.

The gas discharge guide unit may be located in a portion corresponding to the center of the cover portion.

Based on the protruding direction of the electrode leads, the end of the cover part may be positioned farther outward than the end of the lead film.

Based on the protruding direction of the electrode leads, the ends of the electrode leads may be positioned farther outward than the ends of the cover part.

The cover portion may be curved in a direction away from the lead film based on the sealing portion.

The gas discharge guide unit may extend in the protruding direction of the electrode lead, and the end of the gas discharge guide unit adjacent to the outside of the battery case may be surrounded with a lead film.

An end of the gas discharge guide unit adjacent to the inside of the battery case may be exposed at the inside of the battery case.

A gas discharge path may be formed at an interface between the gas discharge guide unit and the lead film.

The adhesive force between the gas discharge guide unit and the lead film may be smaller than the adhesive force between the lead film and the electrode lead or the adhesive force between the lead film and the sealing portion.

The gas discharge guide unit may be a film layer made of at least one of polyimide and polyethylene terephthalate.

The gas discharge guide unit may be a coating layer made of liquid resin.

The gas discharge guiding unit may further comprise a getter material containing calcium oxide (CaO), lithium chloride (LiCl), silicon dioxide (SiO ₂ ) At least one of barium oxide (BaO), barium (Ba), and calcium (Ca).

The gas discharge guide unit may be located on the electrode lead, and an adhesive layer may be formed between the gas discharge guide unit and the electrode lead.

The adhesive force between the gas discharge guiding unit and the lead film may be less than at least one of the adhesive force between the adhesive layer and the gas discharge guiding unit and the adhesive force between the adhesive layer and the electrode lead.

The adhesive layer may be made of tape or adhesive binder.

The lead film may have a gas permeability of 20 to 60 barrers at 60 ℃.

The lead film has a moisture permeation of 0.02g to 0.2g within 10 years at 25 ℃ and 50% rh.

The gas discharge guide unit may have a gas permeability of 40 barrers or more at 60 ℃.

In another aspect of the present disclosure, there is also provided a battery module including the above battery cell.

Technical effects

According to the embodiments, the present disclosure provides a battery cell including a sealing portion from which a battery case extends and a cover portion located on a lead film, and a battery module including the battery cell, such that insulation performance and gas discharge performance may be improved.

In particular, according to one aspect of the present disclosure, a gas discharge path may be formed at an interface between a gas discharge guide unit and a lead film, so that gas in a battery cell may be effectively discharged to the outside while ensuring a relatively easy manufacturing process.

According to another aspect of the present disclosure, since the cover portion may be positioned further outside than the end of the lead film, the insulation performance of the end face of the end of the cover portion may be improved. Even if a crack occurs in the gas discharge path due to an increase in the internal pressure of the battery case, the end face of the end portion of the cover portion is positioned further outside than the gas discharge path, and thus may not come into contact with the electrolyte leaked outside the gas discharge path, and thus the insulating performance may also be improved.

According to another aspect of the present disclosure, by adjusting the shape of the exhaust guide unit, the exhaust performance of the exhaust guide unit and the durability and air tightness of the lead film can be controlled. In addition, if necessary, by changing the shape of the gas discharge guide unit, the manufacturing process can be simplified and the cost can be reduced.

According to another aspect of the present disclosure, by setting the gas permeability and the moisture permeability of the lead film within predetermined ranges, it is possible to more effectively prevent moisture from penetrating from the outside while discharging gas generated inside the battery cell.

The effects of the present disclosure are not limited to the above effects, and effects not mentioned herein will be clearly understood by those skilled in the art from the present specification and drawings.

Drawings

Fig. 1 is a top view illustrating a conventional battery cell.

Fig. 2 is a cross-sectional view taken along the axis A-A' of fig. 1.

Fig. 3 is a top view illustrating a battery cell according to an embodiment of the present disclosure.

Fig. 4 is an enlarged view showing a two-dot chain line region of fig. 3.

Fig. 5 is a sectional view taken along the axis A-A' of fig. 3.

Fig. 6 shows various shapes of the gas discharge guide unit.

Fig. 7 is an enlarged view showing a two-dot chain line region of fig. 5.

Fig. 8 is a diagram showing a gas discharge path formed at an interface between the lead film and the gas discharge guide unit of fig. 7.

Fig. 9 is a diagram showing electrolyte leakage due to cracks generated in a portion of the gas discharge path of fig. 8.

Fig. 10 is a sectional view illustrating a battery cell according to another embodiment of the present disclosure, taken along the axis A-A' of fig. 3.

Fig. 11 is an enlarged view showing a two-dot chain line region of fig. 10.

Fig. 12 is a diagram showing a gas discharge path formed at an interface between the lead film and the gas discharge guide unit of fig. 11.

Fig. 13 is a view showing leakage of an electrolyte due to a crack generated in a portion of the gas discharge path of fig. 12.

Fig. 14 is a sectional view taken along the A-A' axis of fig. 1 according to a comparative example.

Fig. 15 is an enlarged view showing a two-dot chain line region of fig. 14 and shows electrolyte leakage due to cracks generated in a portion of the gas discharge path of fig. 14.

Detailed Description

Hereinafter, various embodiments of the present disclosure will be described in detail with reference to the accompanying drawings so as to be easily implemented by those skilled in the art. The present disclosure may be embodied in a variety of different forms and is not limited to the embodiments described herein.

For clarity of explanation of the present disclosure, parts irrelevant to the description are omitted, and the same or similar parts are given the same reference numerals throughout the specification.

In addition, since the size and thickness of each component shown in the drawings are arbitrarily represented for convenience of description, the present disclosure is not necessarily limited to the drawings. The thickness is exaggerated for clarity in the drawing of various layers and regions. In addition, in the drawings, the thickness of some layers and regions are exaggerated for convenience of explanation.

In addition, throughout the specification, when a part "includes" a certain component, this means that other components may also be included, not excluding other components, unless otherwise mentioned.

In addition, throughout the specification, when referring to the "top view" means that the target portion is viewed from above, and when referring to the "cross-sectional view" means that the vertical cut section of the target portion is viewed from the side.

Hereinafter, a battery cell according to an embodiment of the present disclosure will be described. However, the description will be made herein based on one end of the battery cell, but is not necessarily limited thereto, and the same or similar contents may be described in the case of the other end of the battery cell.

The battery cell 100 according to the embodiment of the present disclosure includes: a battery case 200 having a receiving part 210 in which the electrode assembly 110 is mounted and a sealing part 250 formed by sealing the outer circumference thereof; an electrode lead 300 electrically connected to the electrode tab 150 included in the electrode assembly 110 and protruding outside the battery case 200 via the sealing part 250; and a lead film 400, the lead film 400 being located at a portion corresponding to the sealing portion 250 in at least one of the upper and lower portions of the electrode lead 300. For example, the battery cell 100 has a long side in the direction along the X-axis and a short side in the direction along the Y-axis, and has a smaller thickness in the Z-axis direction than the length of the X-axis or the Y-axis, so that it may be an approximately rectangular plate-shaped unit. The electrode leads 300 may be formed at the short sides of the battery cell 100. Such battery cells 100 are integrated in the Z-axis direction to laminate a plurality of battery cells 100 face to face, which is an effective structure to improve energy density.

The electrode assembly 110 may have a roll core type (winding type), a lamination type (lamination type), or a composite type (lamination/folding type) structure. More specifically, the electrode assembly 110 may include a positive electrode, a negative electrode, and a separator interposed therebetween.

The electrode lead 300 is electrically connected to the electrode tab 150 included in the electrode assembly 110, and protrudes outside the battery case 200 via the sealing part 250. In addition, the lead film 400 is located at a portion corresponding to the sealing part 250 in at least one of the upper and lower parts of the electrode lead 300. Accordingly, the lead film 400 may improve sealability of the sealing part 250 and the electrode lead 300 while preventing short circuits from occurring in the electrode lead 300 during the heat or pressure fusion together with the sealing part 250.

Referring to fig. 3, the lead film 400 may have a wider width than the electrode lead 300. Here, the width of the lead film 400 refers to the distance between one end and the other end of the lead film 400 in the direction (Y-axis direction) perpendicular to the protruding direction (X-axis direction) of the electrode lead 300, and the width of the electrode lead 300 refers to the maximum value of the distance between one end and the other end of the electrode lead 300 in the direction perpendicular to the protruding direction of the electrode lead 300.

The lead film 400 may have a length greater than that of the sealing part 250 and a length smaller than that of the electrode lead 300 based on the protruding direction of the electrode lead 300. Here, the length of the lead film 400 refers to the maximum value of the distance between one end and the other end of the lead film 400 in the protruding direction of the electrode lead 300. The length of the sealing part 250 refers to the maximum value of the distance between one end and the other end of the sealing part 250 in the protruding direction of the electrode lead 300. The length of the electrode lead 300 refers to the maximum value of the distance between one end and the other end of the electrode lead 300 in the protruding direction of the electrode lead 300. Accordingly, the lead film 400 may prevent the side surface of the electrode lead 300 from being exposed to the outside without interfering with the electrical connection of the electrode lead 300.

The battery case 200 may be a laminate sheet including a resin layer and a metal layer. More specifically, the battery case 200 may be made of a laminate sheet, and may include an outer resin layer forming an outermost layer, a barrier metal layer preventing penetration of materials, and an inner resin layer for sealing. For example, the barrier metal layer may be made of an aluminum material.

Here, the battery case 200 may be manufactured by cutting a laminate plate according to a predetermined shape, and the end face resin layers of the outer resin layer, the barrier metal layer, and the inner resin layer may be exposed to the outside at the edges of the battery case 200. Here, the cutting method may employ laser cutting, knife cutting, die punching, or the like, but the present invention is not limited thereto, and a cutting method generally applied when cutting a laminate may also be included in the present embodiment.

However, in the battery case 200, when the barrier metal layer exposed at the edge of the battery case 200 is in contact with an external material or an electrolyte, this may form a circuit and cause a fire. Therefore, in the present embodiment, it is necessary to secure insulation of the barrier metal layer exposed at the edge of the battery case 200.

Fig. 4 is an enlarged view showing a two-dot chain line region of fig. 3. Fig. 5 is a sectional view taken along the axis A-A' of fig. 3.

Referring to fig. 4 and 5, in the present embodiment, the gas discharge guide unit 450 may be inserted into the lead film 400, and the battery case 200 may include a cover portion 270 extending from the sealing portion 250.

Here, the sealing part 250 and the cover part 270 may be integrated with each other. More specifically, since the receiving part 210 and the cover part 270 are thermally or compressively melted in the battery case 200, and the sealing part 250 may be formed between the receiving part 210 and the cover part 270.

In addition, the cover portion 270 may extend from the sealing portion 250 and may protrude in an outward direction of the battery case 200. More specifically, the cover portion 270 may extend from the sealing portion 250 located on the lead film 400. That is, the cover portion 270 may be located on the lead film 400. Here, based on the sealing portion 250, the cover portion 270 may extend in the same direction as the direction in which the lead film 400 protrudes in the outward direction of the battery case 200.

Further, the cover part 270 may be located on the gas discharge guiding unit 450. More specifically, the cover part 270 may be positioned on the gas discharge guiding unit 450 with the lead film 400 interposed therebetween. In other words, the cover portion 270 may be located in a portion corresponding to a portion of the lead film 400 where the gas discharge guiding unit 450 is located. That is, the cover portion 270 may cover a portion of the lead film 400 where the gas discharge guiding unit 450 is located. When the battery case 200 is cut, the battery case 200 may be cut such that the cover portion 270 is longer than the sealing portion 250 in the X-axis direction, thereby providing the cover portion 270 capable of covering the portion where the gas discharge guide unit 450 is located.

For example, the gas discharge guide unit 450 may be located in a portion corresponding to the center of the cover portion 270. In other words, the center line of the gas discharge guide unit 450 and the center line of the cover portion 270 may coincide with each other.

According to this configuration, in the present embodiment, since the cover portion 270 may be located on the gas discharge guiding unit 450 of the lead film 400, the cover portion 270 may cover a portion of the gas discharge path formed by the lead film 400 and the gas discharge guiding unit 450, which is exposed to the outside of the battery case 200. In other words, the cut surface of the battery case 200 may cover the gas discharge path.

Referring to fig. 4, the length of the cover portion 270 may be equal to or greater than the length of the gas discharge guide unit 450 based on a direction perpendicular to the protruding direction of the electrode lead 300. Here, the length of the cover part 270 refers to the maximum value of the distance between one end and the other end of the cover part 270 in the direction orthogonal to the protruding direction of the electrode lead 300. The length of the gas discharge guide unit 450 refers to the maximum value of the distance between one end and the other end of the gas discharge guide unit 450 in the direction orthogonal to the protruding direction of the electrode lead 300.

Accordingly, the cover part 270 may cover the entire part of the lead film 400, which is located outside the battery case 200, of the gas discharge guide unit 450. That is, the entire portion of the gas discharge path formed by the lead film 400 and the gas discharge guide unit 450, which is exposed to the outside of the battery case 200, can be effectively covered.

For example, the length of the cover part 270 may be equal to or less than the length of the lead film 400 based on a direction perpendicular to the protruding direction of the electrode lead 300. Here, the length of the lead film 400 refers to the maximum value of the distance between one end and the other end of the lead film 400 in the direction orthogonal to the protruding direction of the electrode lead 300. That is, the cover portion 270 may cover a part or all of the portion where the lead film 400 is located.

According to the above configuration, in the present embodiment, since the cover portion 270 may have a size similar to that of the lead film 400, it is possible to effectively cover the portion where the gas discharge guide unit 450 is located while increasing the space efficiency of the battery cell 100.

However, the size of the cover portion 270 is not limited thereto, and any size may be included in the present embodiment as long as the portion where the gas discharge guiding unit 450 is located can be covered as described above.

Referring to fig. 4 and 5, the end of the cover part 270 may be positioned farther outward than the end of the lead film 400 based on the protruding direction of the electrode lead 300. In other words, the end of the cover portion 270 may extend from the sealing portion 250 and may extend further outward than the end of the lead film 400.

More specifically, the cover portion 270 may be bent with respect to the sealing portion 250 in a direction away from the lead film 400 (Z-axis direction). Here, the angle at which the cover portion 270 is bent with respect to the sealing portion 250 may be an angle generated due to melting of the sealing portion 250. However, if desired, the angle at which the cover portion 270 is bent with respect to the sealing portion 250 may be adjusted to be smaller or larger than the angle generated by melting of the sealing portion 250.

Accordingly, in the present embodiment, the cover portion 270 may be positioned further outward than the end of the lead film 400, thereby improving the insulation performance of the end face of the end of the cover portion 270. That is, even when a crack occurs in the gas discharge path according to an increase in the internal pressure of the battery case 200, the end face of the end of the cover portion 270 may not be in contact with the electrolyte leaked outside the gas discharge path, since it is positioned further outside than the gas discharge path, and thus the insulation performance may be improved. In other words, by cutting the battery case 200 longer in a portion of the gas discharge path, the cut surface of the battery case 200 sufficiently covers the gas discharge path, and thus, even if the electrolyte leaks, the barrier metal layer exposed to the cut surface of the battery case 200 is not in contact with the leaked electrolyte. Therefore, a circuit is not formed, and insulating performance can be maintained.

Further, based on the protruding direction of the electrode lead 300, the end of the electrode lead 300 may be positioned further outward than the end of the cap portion 270. In other words, the end of the cover part 270 may extend from the sealing part 250 and may extend shorter than the end of the electrode lead 300.

Therefore, in the present embodiment, since the end of the electrode lead 300 is positioned farther outward than the end of the cover part 270, the cover part 270 may improve insulation properties while not interfering with the electrical connection between the electrode lead 300 and other components.

Referring to fig. 4 and 5, the gas discharge guide unit 450 may extend along the protruding direction of the electrode lead 300. More specifically, in the gas discharge guide unit 450, an end of the gas discharge guide unit 450 adjacent to the outside of the battery case 200 may be surrounded with the lead film 400. In other words, the end of the gas discharge guide unit 450 adjacent to the outside of the battery case 200 may not be exposed to the outside of the battery case 200.

In addition, an end of the gas discharge guide unit 450 adjacent to the inside of the battery case 200 may be exposed at the inside of the battery case 200. In other words, the end of the gas discharge guide unit 450 adjacent to the inside of the battery case 200 may be positioned on the same vertical line as the end of the lead film 400, or may be positioned on the inside of the battery case 200 as compared to the end of the lead film 400.

Accordingly, in the lead film 400, since one end of the gas discharge guide unit 450 adjacent to the outside of the battery case 200 is not exposed to the outside of the battery case 200, the sealing force of the battery case 200 caused by the lead film 400 and the sealing part 250 can be improved. In addition, in the lead film 400, since the end of the gas discharge guide unit 450 adjacent to the inside of the battery case 200 is exposed at the inside of the battery case 200, the gas generated in the battery unit 100 may be easily guided along the gas discharge path formed by the gas discharge guide unit 450 and may be effectively discharged to the outside.

With further reference to fig. 5, the thickness H (height in the Z-axis direction) of the lead film 400 on the upper surface of the gas discharge guiding unit 450 may be 100 μm to 300 μm, or 100 μm to 200 μm. When the thickness H of the lead film 400 satisfies the above range, the gas inside the battery case 200 may be more easily discharged to the outside.

Further, referring to fig. 5, the width W of the lead film 400 surrounding the front surface of the gas discharge guide unit 450 may be 2mm or more, or 2mm to 3mm, based on the protruding direction of the electrode lead 300. When the width W of the lead film 400 satisfies the above range, the lead film 400 may not be torn as much as possible while the gas generated inside the battery case 200 is discharged to the outside.

In addition, the gas discharge guide unit 450 may have a thickness D of 50 μm to 150 μm. When the thickness of the gas discharge guide unit 450 satisfies the above range, the gas inside the battery case 200 may be more easily discharged to the outside. Fig. 6 shows various shapes of the gas discharge guide unit. The gas discharge guide unit 450 may be formed in a predetermined pattern to discharge the gas inside the battery case 200.

For example, the gas discharge guide unit 450 may have a rectangular shape extending along the protruding direction of the electrode lead 300, as shown in fig. 4. However, the present disclosure is not limited thereto, and the gas discharge guide unit 450 may have various shapes, such as a circular shape as shown in fig. 6 (a), an elliptical shape as shown in fig. 6 (b), and other straight or curved shapes.

As another example, the gas discharge guiding unit 450 may include a first gas discharge guiding unit 450a along the protruding direction of the electrode lead 300 and a second gas discharge guiding unit 450b extending in a direction perpendicular to the protruding direction of the electrode lead 300, as shown in (c) of fig. 6. Specifically, the first gas discharge guiding unit 450a and the second gas discharge guiding unit 450b may be connected to each other. Here, the second gas discharge guiding unit 450b may be located outside the sealing part 250 based on the sealing part 250 and inside the lead film 400, as shown in (c) of fig. 6; or may be based on the sealing portion 250 being located inside the sealing portion 250 and outside the lead film 400 as shown in (d) of fig. 6. Alternatively, the second gas discharge guiding unit 450b may be located at both the outer side of the lead film 400 and the inner side of the lead film 400 with respect to the sealing portion 250, as shown in (e) of fig. 6. However, the shape of the gas discharge guide unit 450 is not limited to the above, and the gas discharge guide unit 450 may be inserted into the lead film 400 in an appropriate shape. Accordingly, by adjusting the shape of the gas discharge guide unit 450 inserted into the lead film 400, the gas discharge performance of the gas discharge guide unit 450 and the durability and airtightness of the lead film 400 can be controlled. In addition, if necessary, by changing the shape of the gas discharge guiding unit 450, the manufacturing process can be simplified and the cost can be reduced.

For example, only one gas discharge guide unit 450 may be included in the lead film 400, as shown in fig. 4. As another example, a plurality of gas discharge guide units 450 may be inserted into the lead film 400 and positioned to be spaced apart from each other.

Accordingly, the gas discharge performance of the gas discharge guide unit 450 and the durability and airtightness of the lead film 400 can be controlled by adjusting the number of the gas discharge guide units 450 inserted into the lead film 400. In addition, if necessary, by minimizing the number of the gas discharge guide units 450, the manufacturing process can be simplified and the cost can be reduced.

Fig. 7 is an enlarged view showing a two-dot chain line region of fig. 5. Fig. 8 is a diagram showing a gas discharge path formed at an interface between the lead film and the gas discharge guide unit of fig. 7. Fig. 9 is a diagram showing electrolyte leakage due to cracks generated in a portion of the gas discharge path of fig. 8.

Referring to fig. 7 and 8, in the present embodiment, a gas discharge path may be formed at an interface between the gas discharge guide unit 450 and the lead film 400. More specifically, as shown in fig. 7 and 8, the gas discharge path may refer to a space in which at least a portion of the interface between the gas discharge guide unit 450 and the lead film 400 is spaced apart due to the pressure of the gas generated in the battery case 200. In fig. 8, the moving path of the gas is indicated by a broken-line arrow. That is, as shown in the dotted arrow direction in fig. 8, the gas discharge path may refer to a path in which gas is introduced into a space at an interface between the gas discharge guiding unit 450 and the lead film 400 or discharged to the outside.

Here, the adhesive force between the gas discharge guiding unit 450 and the lead film 400 may be less than the adhesive force between the lead film 400 and the electrode lead 300 or the adhesive force between the lead film 400 and the sealing part 250. More specifically, when the pressure inside the battery case 200 increases due to the gas generated in the battery cell 100, the adhesion force of the interface between the gas discharge guide unit 450 and the lead film 400 is relatively lower than the adhesion force between the lead film 400 and other components, and thus at least a portion of the interface between the gas discharge guide unit 450 and the lead film 400 may be spaced apart due to the pressure of the gas generated in the battery cell 100, as shown in fig. 8.

That is, in the present embodiment, as the gas discharge guide unit 450 and the lead film 400 are spaced apart due to the relatively low adhesive force between the gas discharge guide unit 450 and the lead film 400, the gas inside the battery cell 100 may be introduced into the gas discharge channel formed at the interface between the gas discharge guide unit 450 and the lead film 400, and the gas may move along the gas discharge channel and be finally discharged through the lead film 400. The gas introduced into the gas discharge passage may be discharged to the outside according to a pressure difference from the outside.

However, the gas discharge path may include not only a case where the interface between the upper surface of the gas discharge guiding unit 450 and the lead film 400 and the interface between the lower surface of the gas discharge guiding unit 450 and the lead film 400 are spaced apart (as shown in fig. 8), but also a case where the interface between the upper surface of the gas discharge guiding unit 450 and the lead film 400 or the interface between the lower surface of the gas discharge guiding unit 450 and the lead film 400 are spaced apart.

For example, the gas discharge guide unit 450 may be a film layer made of at least one of Polyimide (PI) and polyethylene terephthalate (PET). As another example, the gas discharge guiding unit 450 may be a coating layer made of liquid resin. However, the shape of the gas discharge guiding unit 450 or the material constituting the same is not limited thereto, and any shape or material may be included in the present embodiment as long as the adhesive force of the interface between the gas discharge guiding unit 450 and the lead film 400 may be relatively lower than the adhesive force between the lead film 400 and other components.

Accordingly, since the battery cell according to the present embodiment may form a gas discharge path at the interface between the gas discharge guide unit 450 and the lead film 400 by a relatively low adhesive force between the gas discharge guide unit 450 and the lead film 400, the gas in the battery cell 100 may be effectively discharged to the outside while the manufacturing process is relatively easy.

Further, referring again to fig. 4 and 5, based on the protruding direction of the electrode lead 300, one end of the gas discharge guiding unit 450 may be positioned further inward than the inner surface of the sealing part 250. In the present specification, the inner surface of the sealing part 250 refers to the end of the sealing part 250 adjacent to the inside of the battery case 200, and one end of the gas discharge guiding unit 450 positioned more inward than the inner surface of the sealing part 250 refers to one end of the gas discharge guiding unit 450 positioned more inward than the inner surface of the sealing part 250 toward the inside of the battery case 200. When one end of the gas discharge guiding unit 450 is positioned more inward than the inner surface of the sealing part 250, it does not interfere with the sealing part 250, and thus gas can be more easily introduced into the gas discharge guiding unit 450.

In addition, the other end of the gas discharge guiding unit 450 may be positioned further outward than the outer surface of the sealing part 250 based on the protruding direction of the electrode lead 300. In the present specification, the outer surface of the gas discharge guide unit 450 refers to the end of the sealing part 250 adjacent to the outside of the battery case 200, and the other end of the gas discharge guide unit 450 positioned further outward than the outer surface of the sealing part 250 refers to the other end of the gas discharge guide unit 450 positioned further outward than the outer surface of the sealing part 250 toward the outside of the battery case 200. For example, a space P is provided between the outer surface of the sealing part 250 and the other end of the gas discharge guiding unit 450. If the other end portion of the gas discharge guide unit 450 is positioned more outside than the outer surface of the sealing part 250 as described above, the gas introduced into the gas discharge guide unit 450 may be more easily discharged to the outside. For example, since the other end portion of the gas discharge guide unit 450 does not interfere with the sealing portion 250, the gas introduced into the gas discharge guide unit 450 may be more easily discharged to the outside.

Accordingly, the gas generated inside the battery cell 100 may be discharged toward the gas discharge guide unit 450, and the gas introduced into the gas discharge guide unit 450 may be easily discharged to the outside, as shown in fig. 8. In addition, the amount of gas generated inside the battery cell 100 and discharged to the outside may also be increased. In this way, the gas generated inside the battery case 200 may be easily discharged into the gas discharge guide unit 450 and may be more easily discharged to the outside of the gas discharge guide unit 450.

Further, as shown in fig. 8, the gas introduced into the gas discharge guiding unit 450 may be particularly easily discharged in the Z-axis direction through the lead film 400 on the gas discharge guiding unit 450. For example, when the other end portion of the gas discharge guiding unit 450 is positioned further outward than the outer surface of the sealing part 250, the gas introduced into the gas discharge guiding unit 450 may be discharged in the Z-axis direction in a portion of the lead film 400 between the other end portion of the gas discharge guiding unit 450 and the outer surface of the sealing part 250. As described above, the thickness H of the lead film 400 on the upper surface of the gas discharge guide unit 450 may be 100 μm to 300 μm, and the width W of the lead film 400 around the front surface of the gas discharge guide unit 450 may be 2mm or more, or 2mm to 3mm, based on the protruding direction of the electrode lead 300. As described above, when the other end portion of the gas discharge guide unit 450 is positioned further outside than the outer surface of the sealing part 250, the gas can be discharged through the part located in the Z-axis direction, which is a relatively thin part in the lead film 400. Thus, the gas can be discharged more easily. Further, if the gas discharge path is completely blocked by the sealing part 250 at the time of gas discharge, the gas cannot be smoothly discharged. Therefore, as described above, a space P is provided between the outer surface of the sealing part 250 and the other end of the gas discharge guiding unit 450, so that the gas can be smoothly discharged.

Referring to fig. 9, in the present embodiment, in the gas discharge path formed at the interface between the gas discharge guide unit 450 and the lead film 400, cracks may be formed in a portion of the lead film 400 when a predetermined time passes. More specifically, when the gas inside the battery cell 100 is continuously introduced into and discharged from the gas discharge path, the end of the lead film 400 adjacent to the outside of the battery case 200 may be structurally weakened. Even if the width W of the lead film 400 covering the entire surface of the gas discharge guide unit 450 is 2mm or more to prevent tearing of the lead film 400, cracks may be formed in the lead film as the battery cell 100 continues to be used. In this case, the electrolyte 50 inside the battery cell 100 may leak to the outside through cracks.

Here, referring to fig. 7 to 9, in the battery cell 100 according to the present embodiment, the cover portion 270 may be positioned further outward than the end of the lead film 400, and the end of the cover portion 270 may be positioned further outward than the end of the gas discharge path. Therefore, in the present embodiment, even if a crack occurs so that the electrolyte 50 leaks, the electrolyte leaking outside the gas discharge path does not come into contact with the end face of the end portion of the cover portion 270.

As shown in fig. 9, even if the electrolyte 50 leaks through the crack, the leaked electrolyte is located on the inner resin layer of the cover portion 270, and the leaked electrolyte hardly reaches the barrier metal layer exposed on the end face of the end portion of the cover portion 270. That is, since the barrier metal layer exposed on the end face of the end of the cover portion 270 may not be in contact with the electrolyte leaked to the outside of the gas discharge path, it is possible to prevent the formation of a circuit between the barrier metal layer and the electrolyte, and thus it is also possible to improve the insulation performance and safety accordingly.

In addition, the gas discharge guide unit 450 may further include a material having a function of absorbing or adsorbing moisture introduced from the outside or hydrofluoric acid generated therein. More specifically, the gas discharge guiding unit 450 may further include a getter material. Here, the getter material may refer to a material capable of being evacuated by the action of a gas adsorbed to the chemically activated metal film. For example, the getter material may comprise calcium oxide (CaO), lithium chloride (LiCl), silicon dioxide (SiO ₂ ) At least one of barium oxide (BaO), barium (Ba), and calcium (Ca). As another example, the getter material may have a Metal Organic Framework (MOF) structure. However, the getter material is not limited thereto, and may include all kinds of materials generally classified as getter materials.

Accordingly, in the present embodiment, since the gas discharge guide unit 450 further includes a material capable of absorbing or adsorbing moisture or hydrofluoric acid, the gas discharge guide unit 450 may more easily minimize the penetration degree of moisture or hydrofluoric acid introduced into the battery cell 100 from the outside of the battery cell 100, and may more easily discharge gas generated inside the battery cell 100 to the outside.

In an embodiment of the present disclosure, the gas permeability of the gas discharge guide unit 450 may be greater than or equal to 40 barrers at 60 ℃. For example, the carbon dioxide permeability of the gas discharge guide unit 450 may satisfy the above range.

For example, the gas discharge guiding unit 450 may include at least one of a polyolefin-based material, a fluorine-based material, and a porous ceramic-based material satisfying the above gas permeability values. The polyolefin-based material may include at least one material selected from the group consisting of polypropylene, polyethylene, and polyvinylidene fluoride (PVDF). The fluorine-based material may include at least one material selected from the group consisting of polytetrafluoroethylene and polyvinylidene fluoride.

In one embodiment of the present disclosure, the gas permeability of the lead film 400 may be 20 to 60 barrers, or 30 to 40 barrers at 60 ℃. For example, the carbon dioxide permeability of the lead film 400 may satisfy the above range. Further, the gas permeability may satisfy the above range at 60 ℃ based on the thickness H of the lead film 400 of 200 μm. If the gas permeability of the lead film 400 satisfies the above range, the gas generated inside the battery cell can be more effectively discharged.

In this specification, gas permeability may be measured by ASTM F2476-20.

In one embodiment of the present disclosure, the moisture vapor transmission rate of the lead film 400 may be 0.02g to 0.2g, or 0.02g to 0.04g, or 0.06g, or 0.15g, within 10 years at 25 ℃ and 50% relative humidity. If the moisture penetration amount of the lead film 400 satisfies the above range, penetration of moisture from the lead film 400 can be more effectively prevented.

In an embodiment of the present disclosure, the lead film 400 may have a gas permeability of 20 to 60 barrers at 60 ℃ and may have a moisture permeation amount of 0.02 to 0.2g within 10 years at 25 ℃ and 50% rh. When the gas permeability and the moisture permeability of the lead film 400 satisfy the above ranges, it is possible to more effectively prevent moisture from penetrating from the outside while discharging gas generated inside the battery cell 100.

The moisture penetration amount of the lead film 400 may be measured by using the ASTM F1249 method. At this time, the moisture penetration amount may be measured using MCOON official certified equipment.

In an embodiment of the present disclosure, the lead film 400 may be formed of an adhesive composition made of at least one of a polyolefin-based material, an epoxy resin, and polyvinyl chloride (PVC). The polyolefin-based material may be Polyethylene (PE), polypropylene (PP), or the like. For example, the lead film 400 may be polyethylene, polypropylene, or the like that satisfies the above-described gas permeability and/or moisture permeability values.

In addition, since the lead film 400 is made of the above-described materials, the lead film 400 can maintain the air tightness of the battery cell 100 and prevent the leakage of the internal electrolyte.

Hereinafter, a battery cell according to another embodiment of the present disclosure will be described. However, the battery cell according to this embodiment may be mainly described in the same manner as the battery cell 100 described above, and the gas discharge guide unit 450 will be described in detail based on a portion different from the battery cell 100.

Fig. 10 is a sectional view illustrating a battery cell according to another embodiment of the present disclosure, taken along the A-A' axis of fig. 3.

Referring to fig. 4 and 10, in the present embodiment, unlike fig. 5, a gas discharge guiding unit 450 'may be located on the electrode lead 300'. More specifically, the separate lead film 400' may not be located between the gas discharge guiding unit 450' and the electrode lead 300 '. That is, the gas discharge guide unit 450 'may be inserted into the lead film 400' adjacent to the electrode lead 300 'and may be positioned adjacent to the electrode lead 300'. In other words, the present embodiment may have the following structure: wherein the lead film 400 'surrounds the outer surface of the gas discharge guiding unit 450' after the gas discharge guiding unit 450 'is attached or fixed to the electrode lead 300'.

Accordingly, since the gas discharge guide unit 450 'is positioned adjacent to the electrode lead 300', the thickness of the lead film 400 'surrounding the gas discharge guide unit 450' can also be relatively reduced, which has advantages of reducing manufacturing costs and simplifying manufacturing processes.

In addition, an adhesive layer 470' may be formed between the gas discharge guiding unit 450' and the electrode lead 300'. Here, the adhesive layer 470' may extend along an interface between the gas discharge guiding unit 450' and the electrode lead 300'. At this time, the adhesive layer 470' may be formed on the entire interface or a part of the interface between the gas discharge guiding unit 450' and the electrode lead 300'.

For example, the adhesive layer 470' may be made of tape or adhesive binder. However, the present disclosure is not limited thereto, and any material having an adhesive property capable of fixing the gas discharge guiding unit 450 'and the electrode lead 300' to each other may be applied without limitation.

Accordingly, the gas discharge guide unit 450' may be stably fixed to the electrode lead 300' by the adhesive layer 470'. That is, since the adhesive layer 470' having a relatively high adhesive force is formed between the gas discharge guiding unit 450' and the electrode lead 300', peeling caused by an increase in the internal pressure of the battery cell 100 can be prevented, and the sealing strength of the battery cell 100 can be further improved.

Fig. 11 is an enlarged view showing a two-dot chain line region of fig. 10. Fig. 12 is a diagram showing a gas discharge path formed at an interface between the lead film and the gas discharge guide unit of fig. 11. Fig. 13 is a view showing leakage of an electrolyte due to a crack generated in a portion of the gas discharge path of fig. 12.

Referring to fig. 11 to 13, in the present embodiment, similar to fig. 7 to 9, a gas discharge path may be formed at an interface between the gas discharge guiding unit 450 'and the lead film 400'. However, in the present embodiment, unlike fig. 7 to 9, the gas discharge guiding unit 450' is positioned adjacent to the electrode lead 300', and an adhesive layer 470' is formed between the gas discharge guiding unit 450' and the electrode lead 300 '. Therefore, a gas discharge path may not be formed at the interface between the gas discharge guide unit 450 'and the electrode lead 300'. In fig. 12, the moving path of the gas is indicated by a broken line arrow.

More specifically, in the present embodiment, the adhesive force between the gas discharge guiding unit 450 'and the lead film 400' may be smaller than the adhesive force between the adhesive layer 470 'and the gas discharge guiding unit 450' and/or the adhesive force between the adhesive layer 470 'and the electrode lead 300'.

More specifically, in the present embodiment, when the pressure inside the battery cell 100 increases, the adhesion force of the interface between the gas discharge guide unit 450' and the lead film 400' is relatively smaller than the adhesion force between the lead film 400' and other components, as shown in fig. 12, at least a portion of the interface between the gas discharge guide unit 450' and the lead film 400' may be spaced apart due to the internal pressure of the battery cell 100.

Further, in the present embodiment, the adhesive force of the interface between the gas discharge guiding unit 450 'and the lead film 400' may be smaller than the adhesive force between the gas discharge guiding unit 450 'and the adhesive layer 470' and/or the adhesive force between the adhesive layer 470 'and the electrode lead 300'. Therefore, it is possible to prevent the interfacial peeling between the gas discharge guiding unit 450 'and the electrode lead 400' when the internal pressure of the battery cell 100 increases.

That is, in the present embodiment, since only the interface between the gas discharge guide unit 450 'and the lead film 400' may be peeled off to form the gas discharge path, the sealing strength of the battery cell 100 may be increased while maintaining the gas discharge performance through the gas discharge path. In addition, according to the high sealing strength, the exhaust pressure when the gas generated in the battery cell 100 is discharged to the outside may also be higher, and the safety may also be further improved.

Further, in the present embodiment, the gas discharge path may be formed only at the interface between the gas discharge guide unit 450 'and the lead film 400', and the gas discharge path may induce the electrolyte 50 inside the battery cell 100 to be discharged toward the cover portion 270 even if cracks occur as shown in fig. 13. That is, the insulation performance and safety can be further improved.

Hereinafter, the battery cell according to the comparative example of the present disclosure will be described in detail. The comparative example will be described in comparison with the embodiment according to fig. 3 to 9, but it may also be described in comparison with the embodiment according to fig. 10 to 13.

Fig. 14 is a sectional view taken along the a-a' axis of fig. 1 according to a comparative example. Fig. 15 is an enlarged view showing a two-dot chain line region of fig. 14 and shows that electrolyte leaks due to cracks generated in a portion of the gas discharge path of fig. 14.

Referring to fig. 14 and 15, which relate to a battery cell 10 according to a comparative example, the battery cell 10 of the comparative example is substantially identical to the battery cell of fig. 1 and 2 except that a gas discharge guide unit 45 is included. Hereinafter, the gas discharge guide unit 45 will be described in detail.

Referring to fig. 14, the battery cell 10 according to the comparative example includes a sealing portion 25 formed on a lead film 40 where a gas discharge guide unit 45 is located, and does not include a separate member extending from an end of the sealing portion 25 unlike fig. 3 to 9. That is, the end face of the sealing portion 25 may be exposed to the outside, and in particular, the end face of the sealing portion 25 may be located on the gas discharge path formed by the lead film 40 and the gas discharge guiding unit 45.

Referring to fig. 15, even in the battery cell 10 according to the comparative example, as shown in fig. 9, cracks may occur in a portion of the lead film 40 as a certain time passes, and the electrolyte inside the battery cell 10 may leak to the outside through the cracks 50.

However, in the battery cell 10 according to the comparative example, since the end surface of the sealing part 25 is located on the gas discharge path formed by the lead film 40 and the gas discharge guide unit 45, the end surface of the sealing part 25 may be in contact with the electrolyte leaked outside the gas discharge path, as shown in fig. 15. That is, since the barrier metal layer exposed on the end face of the sealing portion 25 can be in contact with the electrolyte leaked outside the gas discharge path, a circuit is formed between the barrier metal layer and the electrolyte, and safety can be greatly reduced, for example, in the event of a fire.

In contrast, referring to fig. 3 to 9, in the battery cell 100 according to the present embodiment, the cover portion 270 extends from the sealing portion 250 located on the gas discharge guide unit 450, and the end of the cover portion 270 may be positioned further outside than the end of the gas discharge path. That is, unlike the comparative example, in the present embodiment, even if a crack occurs in a part of the lead film 400, the electrolyte leaked from the crack does not contact the end of the cover portion 270, and thus it is possible to prevent a circuit from being formed between the end of the cover portion 270 and the electrolyte, and thus it is also possible to improve insulation performance and safety.

A battery module according to another embodiment of the present disclosure includes the above-described battery cells. Meanwhile, one or more battery modules according to the present embodiment may be packaged in a battery pack case to form a battery pack.

The above battery module and the battery pack including the same may be applied to various devices. These devices may be vehicles such as electric bicycles, electric vehicles, hybrid electric vehicles, etc., but the present disclosure is not limited thereto, and the present disclosure may be applied to various devices that may use the battery module and the battery pack including the battery module, which is also within the scope of the claims of the present disclosure.

Although the preferred embodiments of the present disclosure have been described in detail above, the scope of the claims of the present disclosure is not limited thereto, and various modifications and improvements made by those skilled in the art using the basic idea of the present disclosure defined in the appended claims also fall within the scope of the claims of the present disclosure.

[ reference numerals ]

100: battery cell

110: electrode assembly

200: battery case

210: housing part

250: sealing part

270: cover part

300: electrode lead

400: lead film

450: gas discharge guiding unit

Claims

1. A battery cell, the battery cell comprising:

a battery case having a receiving part in which the electrode assembly is mounted, and a sealing part formed by sealing the outer circumference thereof;

an electrode lead electrically connected to an electrode tab included in the electrode assembly and protruding outside the battery case via the sealing part; and

a lead film located at a portion corresponding to the sealing portion in at least one of an upper portion and a lower portion of the electrode lead,

wherein a gas discharge guide unit is inserted into the lead film,

The battery case includes a cover portion extending from the sealing portion, and

the cover portion is located on the lead film and protrudes in an outward direction of the battery case.

2. The battery cell according to claim 1,

wherein the cover part is located on the gas discharge guiding unit.

3. The battery cell according to claim 2,

wherein the gas discharge guide unit is located in a portion corresponding to the center of the cover portion.

4. The battery cell according to claim 2,

wherein the length of the cover portion is equal to or greater than the length of the gas discharge guide unit based on a direction perpendicular to the protruding direction of the electrode lead.

5. The battery cell according to claim 4,

wherein the length of the cover portion is equal to or less than the length of the lead film based on a direction perpendicular to the protruding direction of the electrode lead.

6. The battery cell according to claim 1,

wherein an end of the cover portion is positioned further outward than an end of the lead film based on a protruding direction of the electrode lead.

7. The battery cell according to claim 6,

wherein, based on the protruding direction of the electrode lead, the end of the electrode lead is positioned further outside than the end of the cover part.

8. The battery cell according to claim 6,

wherein the cover portion is curved in a direction away from the lead film based on the sealing portion.

9. The battery cell according to claim 1,

wherein the gas discharge guide unit extends in the protruding direction of the electrode lead, and surrounds an end of the gas discharge guide unit adjacent to the outside of the battery case with the lead film.

10. The battery cell according to claim 9,

wherein an end of the gas discharge guide unit adjacent to the inside of the battery case is exposed at the inside of the battery case.

11. The battery cell according to claim 1,

wherein a gas discharge path is formed at an interface between the gas discharge guide unit and the lead film.

12. The battery cell according to claim 11,

wherein an adhesive force between the gas discharge guide unit and the lead film is smaller than an adhesive force between the lead film and the electrode lead or an adhesive force between the lead film and the sealing portion.

13. The battery cell according to claim 12,

wherein the gas discharge guide unit is a film layer made of at least one of polyimide and polyethylene terephthalate.

14. The battery cell according to claim 12,

wherein the gas discharge guiding unit is a coating layer made of liquid resin.

15. The battery cell according to claim 12,

wherein the gasThe body emission guiding unit further comprises a getter material containing calcium oxide (CaO), lithium chloride (LiCl), silicon dioxide (SiO ₂ ) At least one of barium oxide (BaO), barium (Ba), and calcium (Ca).

16. The battery cell according to claim 1,

wherein the gas discharge guiding unit is located on the electrode lead, and an adhesive layer is formed between the gas discharge guiding unit and the electrode lead.

17. The battery cell according to claim 16,

wherein an adhesive force between the gas discharge guiding unit and the lead film is smaller than at least one of an adhesive force between the adhesive layer and the gas discharge guiding unit and an adhesive force between the adhesive layer and the electrode lead.

18. The battery cell according to claim 17,

wherein the adhesive layer is made of tape or adhesive binder.

19. The battery cell according to claim 1,

wherein the lead film has a gas permeability of 20 to 60 barrers at 60 ℃.

20. The battery cell according to claim 1,

wherein the lead film has a moisture permeation amount of 0.02g to 0.2g within 10 years under conditions of 25 ℃ and 50% rh.

21. The battery cell according to claim 1,

wherein the gas discharge guide unit has a gas permeability of 40 barrers or more at 60 ℃.

22. A battery module comprising the battery cell according to claim 1.