CN114300791B

CN114300791B - Packaging bags and batteries

Info

Publication number: CN114300791B
Application number: CN202111627248.7A
Authority: CN
Inventors: 高恒; 夏恒涛
Original assignee: Ningde Amperex Technology Ltd
Current assignee: Ningde Amperex Technology Ltd
Priority date: 2021-12-28
Filing date: 2021-12-28
Publication date: 2025-04-01
Anticipated expiration: 2041-12-28
Also published as: CN114300791A

Abstract

A packaging bag comprises a first polymer layer, a metal layer and a second polymer layer arranged in sequence from the inside to the outside. The second polymer layer comprises a main body and a plurality of spaced convex portions, the convex portions being arranged on the surface of the main body away from the metal layer, and a channel being formed between two adjacent convex portions for gas circulation. The present application also provides a battery cell provided with the above packaging bag. When the packaging bag is wrapped with a Mylar film, the Mylar film contacts the end surface of the convex portion away from the main body, reducing the tension on the packaging bag during heat shrinkage of the Mylar film, thereby reducing the risk of poor appearance of the battery cell. The channel is used to discharge the gas in the bubbles generated between the packaging bag and the Mylar film, thereby reducing the risk of appearance dents on the battery cell. In summary, the packaging bag of the present application can improve the appearance yield of the battery cell when the packaging bag is wrapped with a Mylar film.

Description

Packaging bag and battery cell

Technical Field

The application relates to the technical field of batteries, in particular to a packaging bag and a battery cell.

Background

The Mylar film is a polyester film and has the characteristics of high surface flatness, good transparency, chemical corrosion resistance, good flexibility and the like. In the production process of the battery, mylar film is often used for wrapping the battery cell, so that the battery cell can be effectively sealed and protected.

The outer surface of the packaging bag of the conventional battery cell is flat and closely attached to the Mylar film, and the Mylar film is thermally contracted in a vacuum high-temperature environment to lead the outer surface of the packaging bag to be deformed in tension, so that the appearance of the battery cell is poor. And in the process of attaching the Mylar film to the outer surface of the packaging bag, bubbles are easy to appear, and local pits appear on the battery cell in the process of being pressed, so that the appearance of the battery cell is affected. In conclusion, the problem of poor appearance easily occurs when the Mylar film is attached to the existing battery cell.

Disclosure of Invention

In view of the above, it is desirable to provide a package that improves the yield of the cell appearance when the Mylar film is wrapped around the package.

An embodiment of the application provides a packaging bag, which comprises a first polymer layer, a metal layer and a second polymer layer which are sequentially arranged from inside to outside. The second polymer layer comprises a main body part and a plurality of convex parts which are arranged at intervals, the convex parts are arranged on the surface of the main body part, which is away from the metal layer, and a channel is formed between two adjacent convex parts for gas circulation.

There is a difference in height between the convex portion and the surface of the main body portion facing away from the metal layer due to the protruding direction along the convex portion. When the Mylar film wraps the package bag, the Mylar film contacts the end face of the boss remote from the main body. Compared with a packaging bag with the outer surface being completely planar, the contact area between the Mylar film and the surface of the main body part is reduced, and the pulling force on the packaging bag when the Mylar film is subjected to thermal shrinkage is further reduced. When the battery cell is packaged by using the packaging bag, the embodiment of the application can reduce the risk of poor appearance of the battery cell caused by thermal shrinkage of the Mylar film, and a channel is formed between two adjacent convex parts to allow gas to circulate, so that gas in bubbles generated between the packaging bag and the Mylar film can be discharged, and the risk of appearance dent of the battery cell is reduced. In conclusion, the packaging bag can improve the appearance yield of the battery cell when the Mylar film wraps the packaging bag.

In some embodiments of the application, the first cross-section of each of the protrusions is rounded in shape in a direction perpendicular to the direction of protrusion of the protrusions such that the channel includes a first leg extending in the width direction of the body and a second leg extending in the length direction of the body, the first and second legs being in intersecting communication with each other to form a two-dimensional channel for facilitating escape of gas from between the package and the Mylar film.

In some embodiments of the present application, a first connection surface is provided between the convex portion and the main body portion, and a relationship between a first diameter D1 of the first cross section and a first center-of-circle distance D1 between two adjacent first cross sections on the first connection surface and in a width direction of the package bag satisfies D1>100 μm,1< D1/D1<5. By setting the ratio between the first diameter D1 and the first center distance D1 to D1/D1>1, the adjacent two convex portions are arranged at intervals to form a channel. By setting the ratio between the first diameter D1 and the first circular center distance D1 to D1/D1<5, the risk that the Mylar film cannot be stabilized due to overlong interval between two adjacent convex parts is reduced, and the risk that the Mylar film is contacted with the main body part is further reduced.

In some embodiments of the present application, a first connection surface is provided between the protrusion and the main body, and a relationship between a first diameter D1 of the first cross section and a first spacing L1 between two adjacent first cross sections on the first connection surface and along a length direction of the package bag satisfies that D1>100 μm and L1/D1>0.1 enables the two adjacent protrusions to be spaced apart to form a channel.

In some embodiments of the present application, the second cross section of each of the protruding portions has a rectangular shape along a direction perpendicular to the protruding direction of the protruding portion, and defines a width direction of the second cross section as a first direction and a length direction of the second cross section as a second direction. The surface of the main body part is provided with a plurality of groups of convex parts which are arranged at intervals along a first direction, each group of convex parts comprises a plurality of convex parts which are arranged along a second direction, so that the channel comprises a first branch which extends along the first direction and a second branch which extends along the second direction, and the first branch and the second branch are mutually crossed and communicated to form a two-dimensional channel so as to facilitate the escape of gas from between the packaging bag and the Mylar film.

In some embodiments of the application, a first connection surface is provided between the protrusion and the body portion, on which a relationship between the first width W1 of the second cross-section and the first length L3 of the second cross-section satisfies L3/W1>2.

In some embodiments of the present application, a first connection surface is provided between the convex portion and the main body portion, and a relationship between a second pitch L2 between center lines of two adjacent second cross sections in a first direction and a first width W1 of the second cross sections satisfies that W1>100 μm,1< L2/W1<4. By setting the ratio between the first width W1 and the second pitch L2 to L2/W1>1, the adjacent two protrusions are disposed at intervals to form a channel. By setting the ratio between the first width W1 and the second spacing L2 to L2/W1<4, the risk of failure in stabilizing the Mylar film due to excessively long spacing between two adjacent protrusions is reduced, and the risk of contact between the Mylar film and the main body is further reduced.

In some embodiments of the present application, a first connection surface is provided between the convex portion and the main body portion, and a relationship between a third distance L4 between two adjacent second cross sections and a first length L3 of the second cross sections in the second direction on the first connection surface satisfies 0.1< L4/L3<2. By setting the ratio between the first width W1 and the third pitch L4 to L4/L3>0.1, the adjacent two protrusions are disposed at intervals to form a channel. By setting the ratio between the first width W1 and the third spacing L4 to L4/L3<2, the risk of contact of the Mylar film with the body part is reduced.

In some embodiments of the present application, the second polymer layer further includes a plurality of bumps disposed on a surface of the main body facing away from the metal layer, and a third cross section of each bump is circular along a direction perpendicular to a protruding direction of the bump, and at least one bump is disposed between two adjacent bumps in each bump group. When the Mylar film wraps the packaging bag, the Mylar film is contacted with the end face of the convex part far away from the main body part and one end of the convex block far away from the main body part. Channels are formed between adjacent protrusions and bumps for gas flow.

In some embodiments of the present application, the fourth cross section of each of the convex portions has a rectangular shape along a direction perpendicular to the protruding direction of the convex portion, a width direction defining the fourth cross section is a third direction, and a length direction of the fourth cross section is a fourth direction. The main part surface is provided with a plurality of convex parts along third direction interval arrangement, and the both ends of every convex part along the fourth direction and the marginal parallel and level setting that the main part corresponds to form the one-dimensional passageway that extends along the fourth direction between two adjacent convex parts, and then be convenient for gas escape from between wrapping bag and the Mylar film.

In some embodiments of the present application, a first connection surface is provided between the protrusion and the main body portion, and a relationship between a fourth pitch L5 between two adjacent center lines of the fourth cross section and a second width W2 of the fourth cross section in the third direction on the first connection surface satisfies that L5>100 μm and L5/W2>1 enables the adjacent two protrusions to be spaced apart to form a channel.

In some embodiments of the present application, each of the protrusions has a first height H1 along the protruding direction of the protrusion, the first height H1 being the highest height of the protrusion, the relationship between the first height H1 and the first thickness H2 of the main body portion being such that H1>5 μm, H2>5 μm,0.5< H1/H2< 2> is satisfied, enabling each of the protrusions to be stably supported on the main body portion. Thereby reducing the risk of contacting the Mylar film with the main body portion due to the lower protrusion and reducing the risk of transitional bending of the protrusion when contacting the Mylar film due to the higher protrusion.

In some embodiments of the present application, the relationship between the second thickness H3 of the metal layer and the third thickness H4 of the first polymer layer along the protruding direction of the protrusion satisfies H3>20 μm, H4>10 μm,0.2< H4/H3<2, so that the metal layer has excellent water blocking ability and structural strength, and facilitates packaging of the package bag through the first polymer layer.

The embodiment of the application also provides a battery cell, which comprises an electrode assembly, wherein the battery cell further comprises any packaging bag in the embodiment, the electrode assembly is accommodated in the packaging bag, and the first polymer layer of the packaging bag is opposite to the electrode assembly.

In the packaging bag and the battery cell provided with the packaging bag, the height difference exists between the convex part and the surface of the main body part, which is away from the metal layer, along the convex direction of the convex part. When the Mylar film wraps the package bag, the Mylar film contacts the end face of the boss remote from the main body. Compared with a packaging bag with the outer surface being completely planar, the contact area between the Mylar film and the surface of the main body part is reduced, and the pulling force on the packaging bag when the Mylar film is subjected to thermal shrinkage is further reduced. When the battery cell is packaged by using the packaging bag, the embodiment of the application can reduce the risk of poor appearance of the battery cell caused by thermal shrinkage of the Mylar film, and a channel is formed between two adjacent convex parts to allow gas to circulate, so that gas in bubbles generated between the packaging bag and the Mylar film can be discharged, and the risk of appearance dent of the battery cell is reduced. In conclusion, the packaging bag can improve the appearance yield of the battery cell when the Mylar film wraps the packaging bag.

Drawings

Fig. 1 is a schematic structural view of a package according to an embodiment of the present application.

Fig. 2 is a first top view of a package according to an embodiment of the present application.

Fig. 3 is a second top view of a package according to an embodiment of the present application.

Fig. 4 is a third top view of a package according to an embodiment of the present application.

Fig. 5 is a fourth schematic top view of a package according to an embodiment of the present application.

Fig. 6 is a fifth top view of a package according to an embodiment of the present application.

Fig. 7 is a schematic structural diagram of a cell according to an embodiment of the present application.

Description of the main reference signs

Packaging bag 100

Cell 200

First Polymer layer 10

Metal layer 20

Second polymer layer 30

Body portion 31

Convex portion 32

End face 321

First section 322

Second section 323

Fourth section 324

Convex portion group 32a

Channel 33

First branch 331

Second branch 332

First connecting surface 34

Bump 35

First tab 91

Second lug 92

First direction A

Second direction B

Third direction C

Fourth direction D

Center line A1, A2

First diameter D1

First spacing L1

First circle center distance d1

First width W1

Second distance L2

First length L3

Third distance L4

Second width W2

Fourth pitch L5

First height H1

First thickness H2

Second thickness H3

Third thickness H4

The application will be further described in the following detailed description in conjunction with the above-described figures.

Detailed Description

The following description of the technical solutions according to the embodiments of the present application will be given with reference to the accompanying drawings in the embodiments of the present application, and it is apparent that the described embodiments are only some embodiments of the present application, but not all embodiments.

It will be understood that when an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. When an element is referred to as being "disposed on" another element, it can be directly on the other element or intervening elements may also be present.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the description of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and/or" as used herein includes any and all combinations of one or more of the associated listed items. The terms "vertical," "horizontal," "left," "right," "top," "bottom," and the like are used herein for illustrative purposes only and are not intended to limit the application.

It will be appreciated that when the two elements are arranged in parallel/perpendicular, there may be an angle between the two elements that allows for a tolerance of 0 to 10% and that the two elements are greater than, equal to or less than the tolerance that allows for 0 to 10%.

In the above-mentioned packaging bag, there is a difference in height between the convex portion and the surface of the main body portion facing away from the metal layer due to the convex direction of the convex portion. When the Mylar film wraps the package bag, the Mylar film contacts the end face of the boss remote from the main body. Compared with a packaging bag with the outer surface being completely planar, the contact area between the Mylar film and the surface of the main body part is reduced, and the pulling force on the packaging bag when the Mylar film is subjected to thermal shrinkage is further reduced. When the battery cell is packaged by using the packaging bag, the embodiment of the application can reduce the risk of poor appearance of the battery cell caused by thermal shrinkage of the Mylar film, and a channel is formed between two adjacent convex parts to allow gas to circulate, so that gas in bubbles generated between the packaging bag and the Mylar film can be discharged, and the risk of appearance dent of the battery cell is reduced. In conclusion, the packaging bag can improve the appearance yield of the battery cell when the Mylar film wraps the packaging bag.

Embodiments of the present application will be further described with reference to the accompanying drawings.

Referring to fig. 1 and 2 together, an embodiment of the present application provides a packaging bag 100, which includes a first polymer layer 10, a metal layer 20 and a second polymer layer 30 sequentially disposed from inside to outside.

The second polymer layer 30 includes a main body 31 and a plurality of protrusions 32 arranged at intervals, the protrusions 32 are disposed on a surface of the main body 31 facing away from the metal layer 20, and a channel 33 is formed between two adjacent protrusions 32 to allow gas to circulate.

When the Mylar film wraps the packaging bag 100, the Mylar film contacts with the end surface 321 of the protrusion 32 away from the main body 31, and the protrusion 32 can be adaptively bent by reducing the contact area between the Mylar film and the surface of the main body 31 and by applying tension to the protrusion 32 by the Mylar film heat shrinkage, the tension to the main body 31 by the Mylar film heat shrinkage is reduced, and the tension to the packaging bag 100 by the Mylar film heat shrinkage is further reduced.

In the above-described package bag 100, there is a difference in height between the convex portion 32 and the surface of the main body portion 31 facing away from the metal layer 20 due to the convex direction of the convex portion 32. When the Mylar film is wrapped around the package 100, the Mylar film contacts the end 321 of the boss 32 distal from the body portion 31. Compared with the packaging bag with the completely planar outer surface, the contact area between the Mylar film and the surface of the main body 31 is reduced, and the pulling force of the Mylar film on the packaging bag 100 during thermal shrinkage is further reduced. When the battery cell is packaged by using the packaging bag 100, the risk of poor appearance of the battery cell caused by thermal shrinkage of the Mylar film can be reduced, and in addition, a channel is formed between two adjacent convex parts 32 for gas circulation, so that gas in bubbles generated between the packaging bag 100 and the Mylar film is discharged, and the risk of appearance dent of the battery cell is reduced. In summary, the above package bag 100 can improve the appearance yield of the battery cell when the Mylar film wraps the package bag 100.

In some embodiments, the second polymer layer 30 is made of a nylon material. The second polymer layer 30 serves to reduce the risk of air infiltration into the interior of the cell, maintain the environment inside the package 100, and at the same time enhance the deformability of the package 100.

In some embodiments, the metal layer 20 is made of an aluminum material. The metal layer 20 serves to reduce the risk of moisture penetrating into the inside of the battery cell and to improve the structural strength of the package 100. Specifically, the aluminum material reacts with oxygen in the air to form a dense oxide film, so that the risk of water vapor penetrating into the cell is reduced.

In some embodiments, the first polymer layer 10 is made of a polypropylene material. The first polymer layer 10 is melted at a preset temperature and has a viscosity to facilitate the encapsulation of the package 100. And the polypropylene material is not dissolved, swelled, etc. by the organic solvent (e.g., electrolyte) in the package 100, reducing the risk of corrosion of the metal layer 20.

With continued reference to fig. 1 and 2, in some embodiments, along the protruding direction of the protruding portions 32, each protruding portion 32 has a first height H1, and the first height H1 is the highest height of the protruding portions 32. It will be appreciated that the end surface 321 of each protrusion 32 far from the main body 31 may be a plane, an arc surface, or an irregular surface, and when the protrusion is an arc surface or an irregular surface, the distance between the end of the arc surface or the irregular surface furthest from the main body 31 and the main body 31 is the highest height of the protrusion 32 along the protruding direction of the protrusion 32.

The relationship between the first height H1 and the first thickness H2 of the body portion 31 satisfies that H1>5 μm, H2>5 μm,0.5< H1/H2<2, each of the projections 32 can be stably supported on the body portion 31. Thereby reducing the risk of Mylar film coming into contact with the body portion 31 due to the lower protrusion 32 and reducing the risk of transitional bending of the protrusion 32 when in contact with Mylar film due to the higher protrusion 32.

The relationship between the second thickness H3 of the metal layer 20 and the third thickness H4 of the first polymer layer 10 along the protruding direction of the protrusion 32 satisfies that H3>20 μm, H4>10 μm,0.2< H4/H3<2, the metal layer 20 can be improved to have excellent water blocking ability and structural strength, and the package bag 100 passing through the first polymer layer 10 is facilitated.

In some embodiments, the package 100 further includes a glue layer (not shown) disposed between the first polymer layer 10 and the metal layer 20, and between the metal layer 20 and the second polymer layer 30 to improve the stability of the connection between the first polymer layer 10, the metal layer 20, and the second polymer layer 30 and the overall structural strength of the package 100. In some embodiments, the thickness of the glue layer is <5um.

With continued reference to fig. 1 and 2, in some embodiments, the first cross-section 322 of each protrusion 32 is circular in shape along a direction perpendicular to the protruding direction of the protrusion 32, i.e., the protrusion 32 may be cylindrical or frustoconical.

When the Mylar film is wrapped around the package 100, the Mylar film contacts the end surface 321 of the boss 32 remote from the main body 31, and a channel 33 is formed between two adjacent bosses 32 for gas communication. Specifically, the channel 33 includes a first branch 331 extending along the width direction of the main body 31 and a second branch 332 extending along the length direction of the main body 31, and the first branch 331 and the second branch 332 are mutually crossed and communicated to form a two-dimensional channel 33, so as to facilitate the escape of gas from between the packaging bag 100 and the Mylar film.

In some embodiments, the protruding portion 32 is hemispherical away from the end surface 321 of the main body 31, so as to reduce the contact area between the Mylar film and the end surface 321, and further reduce the adhesion between the Mylar film and the end surface 321, so as to reduce the pulling force on the packaging bag 100 when the Mylar film is torn off, and reduce the risk of poor appearance of the battery cell.

It is understood that in some embodiments, the end face 321 may be planar, arcuate, irregular, or the like.

With continued reference to fig. 2, in some embodiments, a first connection surface 34 is provided between the boss 32 and the body 31, i.e., the area of the surface of the body 31 facing the boss 32 that is connected to the boss 32. The relationship between the first diameter D1 of the first cross section and the first spacing L1 between the adjacent two first cross sections on the first connecting surface 34 and in the width direction of the package bag 100 (as may be the first direction a described below) satisfies that D1>100 μm, L1/D1>0.1, enables the adjacent two convex portions 32 to be disposed at intervals to form the passage 33.

In some embodiments, L1/D1 may take on one of values 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, etc.

Referring to FIG. 3, in some embodiments, the relationship between the first diameter D1 of the first cross-section 322 and the first center distance D1 between two adjacent first cross-sections 322 satisfies D1>100 μm,1< D1/D1<5, at the first connecting surface 34 and along the length of the package 100 (e.g., the second direction B described below).

By setting the ratio between the first diameter D1 and the first center-of-circle distance D1 to D1/D1>1, the adjacent two convex portions 32 are disposed at intervals to form the passage 33. By setting the ratio between the first diameter D1 and the first center of circle distance D1 to D1/D1<5, the risk of failure in stabilizing the Mylar film due to the excessively long distance between the adjacent two convex sections 32 is reduced, and the risk of contact between the Mylar film and the main body section 31 is further reduced.

In some embodiments, D1/D1 may take on one of values 1.5, 2, 2.5, 3, 3.5, 4, 4.5, etc.

Referring to fig. 1 and fig. 4 together, in some embodiments, the second section 323 of each protrusion 32 has a rectangular shape along a direction perpendicular to the protruding direction of the protrusion 32, i.e. the protrusion 32 may have a cuboid shape or a prismatic table shape. The width direction of the second section 323 is defined as a first direction a, and the length direction of the second section 323 is defined as a second direction B. The surface of the main body 31 is provided with a plurality of sets of projections 32a arranged at intervals along the first direction a, each set of projections 32a including a plurality of projections 32 arranged along the second direction B.

When the Mylar film is wrapped around the package 100, the Mylar film contacts the end surface 321 of the boss 32 remote from the main body 31, and a channel 33 is formed between two adjacent bosses 32 for gas communication. Specifically, the channel 33 includes a first branch 331 extending in the first direction a and a second branch 332 extending in the second direction B, and the first branch 331 and the second branch 332 are in cross communication with each other to form a two-dimensional channel 33 for facilitating the escape of gas from between the package 100 and the Mylar film.

In some embodiments, the protruding portion 32 is away from the end surface 321 of the main body 31 and is curved, so as to reduce the contact area between the Mylar film and the end surface 321, further reduce the adhesion between the Mylar film and the end surface 321, and facilitate reducing the pulling force on the packaging bag 100 when the Mylar film is torn off, so as to reduce the risk of poor appearance of the battery cell. In some embodiments, the contour of the end surface 321 extends in an arc shape, as viewed in the second direction B.

It will be appreciated that in some embodiments, the end face 321 may be planar, irregular, or the like.

In some embodiments, the first direction A is disposed in the same direction as the width direction of the main body 31, and the second direction B is disposed in the same direction as the length direction of the main body 31.

It will be appreciated that in other embodiments, the first direction a is disposed in the same direction as the length direction of the main body 31, and the second direction B is disposed in the same direction as the width direction of the main body 31.

It will be appreciated that in other embodiments, the first direction a is disposed obliquely to the width direction of the main body portion 31, and/or the second direction B is disposed obliquely to the width direction of the main body portion 31.

With continued reference to FIG. 4, in some embodiments, the relationship between the first width W1 of the second section 323 and the first length L3 of the second section 323 satisfies L3/W1>2 at the first connecting surface 34.

In some embodiments, L3/W1 may take on one of values 2, 3,4, 5, 6, 7, 8, etc.

In some embodiments, the relationship between the second spacing L2 between the centerlines A1 of two adjacent second sections 323 along the first direction A and the first width W1 of the second sections 323 satisfies W1>100 μm,1< L2/W1<4 on the first connection surface 34.

By setting the ratio between the first width W1 and the second pitch L2 to L2/W1>1, the adjacent two projections 32 are disposed at intervals to form the passage 33. By setting the ratio between the first width W1 and the second pitch L2 to L2/W1<4, the risk of failure to stabilize the Mylar film due to the excessively long pitch between the adjacent two convex sections 32 is reduced, and the risk of contact of the Mylar film with the main body section 31 is further reduced.

In some embodiments, L2/W1 may take on one of values 1.5, 2, 2.5, 3, 3.5, etc.

In some embodiments, the relationship between the third spacing L4 between two adjacent second sections 323 and the first length L3 of the second sections 323 in the second direction B satisfies 0.1< L4/L3<2 on the first connecting surface 34.

By setting the ratio between the first width W1 and the third pitch L4 to L4/L3>0.1, the adjacent two projections 32 are arranged with a spacing therebetween to form the passage 33. By setting the ratio between the first width W1 and the third pitch L4 to L4/L3<2, the risk of contacting the Mylar film with the main body portion 31 is reduced.

In some embodiments, L4/L3 may take on a value of one of 0.2, 0.4, 0.6, 0.8, 1, 1.2, 1.4, 1.6, 1.8, etc.

Referring to fig. 5, in some embodiments, the second polymer layer 30 further includes a plurality of bumps 35, and the bumps 35 are disposed on a surface of the main portion 31 facing away from the metal layer 20. The third section 351 of each bump 35 has a circular shape in a direction perpendicular to the protruding direction of the protrusion 32, i.e., the protrusion 32 may have a cylindrical shape or a truncated cone shape.

In each of the convex portion groups 32a, at least one projection 35 is provided between two adjacent convex portions 32. When the Mylar film is wrapped around the package bag 100, the Mylar film is in contact with the end 321 of the boss 32 distal from the main body 31 and the end of the bump 35 distal from the main body 31. Channels 33 are formed between adjacent bosses 32 and bumps 35 for gas flow.

Referring to fig. 1 and 6, in some embodiments, the fourth section 324 of each protrusion 32 is rectangular in shape along a direction perpendicular to the protruding direction of the protrusion 32, i.e. the protrusion 32 may be rectangular or prismatic. The width direction of the fourth section 324 is defined as the third direction C, and the length direction of the fourth section 324 is defined as the fourth direction D. The surface of the main body 31 is provided with a plurality of protrusions 32 arranged at intervals along the third direction C, and both ends of each protrusion 32 along the fourth direction D are arranged flush with the corresponding edges of the main body 31.

When the Mylar film wraps the package bag 100, the Mylar film contacts the end surface 321 of the protrusion 32 away from the main body 31, and a one-dimensional channel 33 extending in the fourth direction D is formed between two adjacent protrusions 32 to allow gas to circulate, thereby facilitating the escape of gas from between the package bag 100 and the Mylar film.

In some embodiments, the protruding portion 32 is away from the end surface 321 of the main body 31 and is curved, so as to reduce the contact area between the Mylar film and the end surface 321, further reduce the adhesion between the Mylar film and the end surface 321, and facilitate reducing the pulling force on the packaging bag 100 when the Mylar film is torn off, so as to reduce the risk of poor appearance of the battery cell. In some embodiments, the contour of the end surface 321 extends in an arc shape as viewed in the fourth direction D.

In some embodiments, the third direction C is disposed in the same direction as the width direction of the main body portion 31, and the fourth direction D is disposed in the same direction as the length direction of the main body portion 31.

It will be appreciated that in other embodiments, the third direction C is disposed in the same direction as the length direction of the main body 31, and the fourth direction D is disposed in the same direction as the width direction of the main body 31.

It will be appreciated that in other embodiments, the third direction C is disposed obliquely to the width direction of the main body portion 31, and/or the fourth direction D is disposed obliquely to the width direction of the main body portion 31.

In some embodiments, the relationship between the fourth spacing L5 between the centerlines A2 of adjacent two fourth sections 324 and the second width W2 of the fourth sections 324 in the third direction C on the first connection face 34 satisfies that W2>100 μm, L5/W2>1 enables spacing between adjacent two protrusions 32 to form the channel 33.

In some embodiments, L5/W2 may take on a value of one of 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, etc.

It is understood that in some embodiments, the cross-section of each protrusion 32 may also be one of square, triangular, polygonal, irregular, etc. along a direction perpendicular to the protruding direction of the protrusion 32.

It will be appreciated that in some embodiments, a pre-cut surface is provided between the tab 32 and the body 31, and that when the Mylar film is removed, the tab 32 is separated from the body 31 by the adhesion of the Mylar film, thereby flattening the outer surface of the second polymer layer 30.

Referring to fig. 7, an embodiment of the application provides a battery cell 200 including an electrode assembly (not shown). The battery cell 200 further includes any of the package bags 100 of the above embodiments, and the electrode assembly is accommodated in the package bag 100 and may be opposite to the first polymer layer 10.

In some embodiments, the battery cell 200 further includes a first tab 91 and a second tab 92, where one of the first tab 91 and the second tab 92 is a positive tab and the other is a negative tab. The first tab 91 has one end connected to the electrode assembly and the other end protruding from the package bag 100. The second tab 92 has one end connected to the electrode assembly and the other end protruding from the package 100. The first tab 91 and the second tab 92 are disposed on the same side.

In the package 100 and the battery cell 200 provided with the package 100, there is a height difference between the protruding portion 32 and the surface of the main body portion 31 facing away from the metal layer 20 due to the protruding direction of the protruding portion 32. When the Mylar film is wrapped around the package 100, the Mylar film contacts the end 321 of the boss 32 distal from the body portion 31. Compared with the packaging bag with the completely planar outer surface, the contact area between the Mylar film and the surface of the main body 31 is reduced, and the pulling force of the Mylar film on the packaging bag 100 during thermal shrinkage is further reduced. When the battery cell is packaged by using the packaging bag 100, the risk of poor appearance of the battery cell caused by thermal shrinkage of the Mylar film can be reduced, and in addition, a channel is formed between two adjacent convex parts 32 for gas circulation, so that gas in bubbles generated between the packaging bag 100 and the Mylar film is discharged, and the risk of appearance dent of the battery cell is reduced. In summary, the above package bag 100 can improve the appearance yield of the battery cell when the Mylar film wraps the package bag 100.

Further, other variations within the spirit of the present application will occur to those skilled in the art, and it is intended, of course, that such variations be included within the scope of the present application as disclosed herein.

Claims

1. A packaging bag, comprising a first polymer layer, a metal layer and a second polymer layer arranged in sequence from the inside to the outside, characterized in that: the second polymer layer comprises a main body and a plurality of convex portions arranged at intervals, the convex portions are arranged on a surface of the main body away from the metal layer, and a channel is formed between two adjacent convex portions for gas circulation;

Along a direction perpendicular to the protruding direction of the protrusion, the shape of the first cross section of each protrusion is circular, a first connecting surface is provided between the protrusion and the main body, on the first connecting surface and along the width direction of the packaging bag, the relationship between the first diameter D1 of the first cross section and the first center distance d1 between two adjacent first cross sections satisfies: D1＞100μm, 1＜d1/D1＜5, on the first connecting surface and along the length direction of the packaging bag, the relationship between the first diameter D1 of the first cross section and the first distance L1 between two adjacent first cross sections satisfies: D1＞100μm, L1/D1＞0.1; or

Along the direction perpendicular to the protruding direction of the protrusion, the shape of the second cross-section of each protrusion is rectangular, the width direction of the second cross-section is defined as the first direction, the length direction of the second cross-section is defined as the second direction, a plurality of the protrusions are arranged along the second direction to form a protrusion group, a plurality of the protrusion groups are arranged at intervals along the first direction, a first connecting surface is provided between the protrusion and the main body, on the first connecting surface, along the first direction, the relationship between the second spacing L2 between the center lines of two adjacent second cross-sections and the first width W1 of the second cross-section satisfies: W1＞100μm, 1＜L2/W1＜4, on the first connecting surface, along the second direction, the relationship between the third spacing L4 between two adjacent second cross-sections and the first length L3 of the second cross-section satisfies: 0.1＜L4/L3＜2.

2. The packaging bag as described in claim 1 is characterized in that: when the shape of the second cross-section of each of the protrusions is rectangular, a first connecting surface is provided between the protrusion and the main body, and on the first connecting surface, the relationship between the first width W1 of the second cross-section and the first length L3 of the second cross-section satisfies: L3/W1>2.

3. The packaging bag as described in claim 1 is characterized in that: when the shape of the second cross-section of each of the protrusions is rectangular, the second polymer layer also includes a plurality of bumps, and the bumps are arranged on the surface of the main body away from the metal layer. Along the direction perpendicular to the protruding direction of the protrusions, the shape of the third cross-section of each of the bumps is circular, and in each group of the protrusions, at least one bump is arranged between two adjacent protrusions.

4. The packaging bag as described in claim 1 is characterized in that: along the direction perpendicular to the protruding direction of the protrusion, the shape of the fourth cross-section of each of the protrusions is rectangular, the width direction of the fourth cross-section is defined as the third direction, the length direction of the fourth cross-section is defined as the fourth direction, and a plurality of protrusions arranged at intervals along the third direction are provided on the surface of the main body, and both ends of each of the protrusions along the fourth direction are arranged flush with the corresponding edge of the main body.

5. The packaging bag as described in claim 4 is characterized in that: a first connecting surface is provided between the convex portion and the main body portion, and on the first connecting surface, along the third direction, the relationship between the fourth spacing L5 between the center lines of two adjacent fourth cross sections and the second width W2 of the fourth cross section satisfies: L5＞100μm, L5/W2＞1.

6. The packaging bag as described in claim 1 is characterized in that: along the protruding direction of the protrusion, each of the protrusions has a first height H1, the first height H1 is the highest height of the protrusion, and the relationship between the first height H1 and the first thickness H2 of the main body satisfies: H1＞5μm, H2＞5μm, 0.5＜H1/H2＜2.

7. The packaging bag according to claim 1, characterized in that: along the protruding direction of the protrusion, the relationship between the second thickness H3 of the metal layer and the third thickness H4 of the first polymer layer satisfies: H3＞20μm, H4＞10μm, 0.2＜H4/H3＜2.

8. A battery cell, comprising an electrode assembly, characterized in that: the battery cell further comprises a packaging bag as claimed in any one of claims 1 to 7, and the electrode assembly is accommodated in the packaging bag.

9 . The battery cell according to claim 8 , further comprising a Mylar film, wherein the Mylar film is in contact with an end surface of the protrusion away from the main body.