CN114300791A

CN114300791A - Packaging bag and battery cell

Info

Publication number: CN114300791A
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: 2022-04-08

Abstract

A packaging bag 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 arranged at intervals, the convex parts are arranged on the surface of the main body part, which is far away from the metal layer, and a channel is formed between every two adjacent convex parts to allow gas to flow through. This application still provides the electric core that is equipped with above-mentioned wrapping bag. When the Mylar film wraps the packaging bag, the Mylar film is in contact with the end face of the convex part far away from the main body part, so that the tension on the packaging bag during thermal shrinkage of the Mylar film is reduced, and the risk of poor appearance of the battery core is reduced. The channels are used to vent gas from bubbles generated between the packaging bag and the Mylar film to reduce the risk of cosmetic dents in the cell. In conclusion, the packaging bag of the application can improve the appearance yield of the battery core when the Mylar film wraps the packaging bag.

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 core.

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, the Mylar film is commonly used for wrapping the battery core, and the battery core can be effectively and reliably sealed and protected.

The outer surface of a packaging bag of a conventional battery core is flat and is tightly attached to the Mylar film, and the Mylar film is subjected to thermal shrinkage in a vacuum high-temperature environment to cause the outer surface of the packaging bag to be stretched and deformed, so that the appearance of the battery core is poor. And air bubbles easily appear in the process of pasting the Mylar film to be pasted on the outer surface of the packaging bag, and local concave points appear in the battery cell in the compression process, so that the appearance of the battery cell is influenced. In conclusion, the problem of poor appearance is easy to occur when the conventional battery core is attached with the Mylar film.

Disclosure of Invention

In view of the above, it is desirable to provide a packaging bag capable of improving the yield of the appearance of the battery cell when the packaging bag is wrapped with the Mylar film.

An embodiment of the present application provides a packaging bag, including a first polymer layer, a metal layer and a second polymer layer arranged in order from inside to outside. The second polymer layer comprises a main body part and a plurality of convex parts arranged at intervals, the convex parts are arranged on the surface of the main body part, which is far away from the metal layer, and a channel is formed between every two adjacent convex parts to allow gas to flow through.

Because of the protruding direction of the convex part, a height difference exists between the convex part and the surface of the main body part, which is far away from the metal layer. When the Mylar film wraps the packaging bag, the Mylar film is in contact with the end face of the convex part far away from the main body part. Compared with a packaging bag with a completely planar outer surface, the contact area between the Mylar film and the surface of the main body part is reduced, and further the tension on the packaging bag during the thermal shrinkage of the Mylar film is reduced. When using this wrapping bag packing electricity core, the embodiment of this application can reduce the bad risk of electric core because of the Mylar membrane thermal contraction leads to the outward appearance, forms the passageway in order to supply the gas circulation between two adjacent convex parts in addition, can discharge the gas in the bubble that produces between wrapping bag and the Mylar membrane to reduce the risk that the outward appearance indents appear in the electric core. 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 present application, the first cross-section of each protrusion is circular in shape in a direction perpendicular to the direction of protrusion of the protrusion, such that the channel comprises a first branch extending in a width direction of the main body and a second branch extending in a length direction of the main body, the first branch and the second branch being in cross communication with each other to form a two-dimensional channel for facilitating the escape of gas from between the bag and the Mylar film.

In some embodiments of the present application, a first connecting 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 distance D1 between two adjacent first cross sections at the first connecting surface and along the width direction of the packaging bag satisfies: d1 is more than 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 projections are spaced apart to form a channel. By setting the ratio of the first diameter D1 to the first center distance D1 to D1/D1 < 5, the risk of the Mylar film being unstable due to too long a distance between two adjacent protrusions is reduced, and the risk of the Mylar film contacting the body portion is reduced.

In some embodiments of the present application, a first connecting 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 distance L1 between two adjacent first cross sections at the first connecting surface and along the length direction of the packaging bag satisfies: d1 & gt 100 μm, L1/D1 & gt 0.1, and the adjacent two convex parts can be arranged at intervals to form a channel.

In some embodiments of the present application, the second cross-section of each protrusion is rectangular along a direction perpendicular to the protruding direction of the protrusion, and the width direction of the second cross-section is defined as the first direction, and the length direction of the second cross-section is defined as the 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 that air can escape from the packaging bag and the Mylar film.

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

In some embodiments of the present application, a first connection surface is disposed between the convex portion and the main body portion, and a relationship between a second distance L2 between center lines of two adjacent second cross-sections along the first direction and a first width W1 of the second cross-sections satisfies: w1 is more than 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 projections are spaced apart to form a channel. By setting the ratio between the first width W1 and the second pitch L2 to L2/W1 < 4, the risk of the Mylar film not being stabilized due to too long a pitch between two adjacent protrusions is reduced, and the risk of the Mylar film coming into contact with the body portion is 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 section along 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 projections are spaced apart to form a channel. By setting the ratio between the first width W1 and the third pitch L4 to L4/L3 < 2, the risk of the Mylar film coming into contact with the body portion is reduced.

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

In some embodiments of the present application, the shape of the fourth cross section of each protrusion along a direction perpendicular to the protruding direction of the protrusion is rectangular, and the width direction of the fourth cross section is defined as the third direction, and the length direction of the fourth cross section is defined as the fourth direction. The surface of the main body part is provided with a plurality of convex parts which are arranged at intervals along the third direction, and two ends of each convex part along the fourth direction are flush with the corresponding edge of the main body part, so that a one-dimensional channel extending along the fourth direction is formed between every two adjacent convex parts, and further, the gas can escape from the packaging bag and the Mylar film conveniently.

In some embodiments of the present application, a first connection surface is disposed between the convex portion and the main body portion, and a relationship between a fourth distance L5 between center lines of two adjacent fourth cross sections along the third direction and a second width W2 of the fourth cross section satisfies: l5 > 100 μm, L5/W2 > 1, and it is possible to arrange the adjacent two projections at intervals to form a channel.

In some embodiments of the present application, each of the protrusions has a first height H1 along a protruding direction of the protrusion, the first height H1 is a highest height of the protrusion, and a relationship between the first height H1 and the first thickness H2 of the main body portion satisfies: h1 & gt 5 μm, H2 & gt 5 μm, 0.5 & lt H1/H2 & lt 2, each convex portion can be stably supported on the main body portion. And further, the risk of the contact between the Mylar film and the main body part due to the low convex part is reduced, and the risk of the transition bending of the convex part when the convex part is in contact with the Mylar film due to the high convex part is reduced.

In some embodiments of the present application, a relationship between the second thickness H3 of the metal layer and the third thickness H4 of the first polymer layer in the projection direction of the convex portion satisfies: h3 is more than 20 mu m, H4 is more than 10 mu m, and H4/H3 is more than 0.2 and less than 2, so that the metal layer has excellent water resistance and structural strength, and the packaging bag passing through the first polymer layer is convenient.

Embodiments of the present application further provide a battery cell, which includes an electrode assembly, and the battery cell further includes any one of the packaging bags in the embodiments, where 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 wrapping bag of this application and the electric core that is equipped with the wrapping bag, because of the bulge direction along the convex part, there is the difference in height between the surface that convex part and main part deviate from the metal level. When the Mylar film wraps the packaging bag, the Mylar film is in contact with the end face of the convex part far away from the main body part. Compared with a packaging bag with a completely planar outer surface, the contact area between the Mylar film and the surface of the main body part is reduced, and further the tension on the packaging bag during the thermal shrinkage of the Mylar film is reduced. When using this wrapping bag packing electricity core, the embodiment of this application can reduce the bad risk of electric core because of the Mylar membrane thermal contraction leads to the outward appearance, forms the passageway in order to supply the gas circulation between two adjacent convex parts in addition, can discharge the gas in the bubble that produces between wrapping bag and the Mylar membrane to reduce the risk that the outward appearance indents appear in the electric core. 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 packaging bag according to an embodiment of the present application.

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

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

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

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

Description of the main elements

Packaging bag 100

Battery cell 200

First polymer layer 10

Metal layer 20

Second polymer layer 30

Main body 31

Convex portion 32

End face 321

First cross section 322

Second section 323

Fourth cross-section 324

Convex part group 32a

Channel 33

First branch 331

Second branch 332

First connection surface 34

Bump 35

First tab 91

Second tab 92

First direction A

Second direction B

Third direction C

A fourth direction D

Center lines A1, A2

First diameter D1

First spacing L1

First center distance d1

First width W1

Second spacing L2

First length L3

Third spacing L4

Second width W2

Fourth spacing L5

First height H1

First thickness H2

Second thickness H3

Third thickness H4

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

Detailed Description

The technical solutions in the embodiments of the present application will be described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the 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 present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used herein, the term "and/or" 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 as used herein are for illustrative purposes only and are not intended to limit the present application.

It will be understood that when two elements are disposed in the same direction when they are disposed in parallel/perpendicular, there can be an angle between the elements, a tolerance of 0- ± 10% between the elements, and a tolerance of 0- ± 10% greater, equal or less than the tolerance allowed.

In the packaging bag, the height difference exists between the convex part and the surface of the main body part, which is far away from the metal layer, along the convex direction of the convex part. When the Mylar film wraps the packaging bag, the Mylar film is in contact with the end face of the convex part far away from the main body part. Compared with a packaging bag with a completely planar outer surface, the contact area between the Mylar film and the surface of the main body part is reduced, and further the tension on the packaging bag during the thermal shrinkage of the Mylar film is reduced. When using this wrapping bag packing electricity core, the embodiment of this application can reduce the bad risk of electric core because of the Mylar membrane thermal contraction leads to the outward appearance, forms the passageway in order to supply the gas circulation between two adjacent convex parts in addition, can discharge the gas in the bubble that produces between wrapping bag and the Mylar membrane to reduce the risk that the outward appearance indents appear in the electric core. In conclusion, the packaging bag can improve the appearance yield of the battery cell when the Mylar film wraps the packaging bag.

The embodiments of the present application will be further explained with reference to the drawings.

Referring to fig. 1 and 2 together, one embodiment of the present application provides a package 100 including 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 for gas to flow through.

When the Mylar film wraps the packaging bag 100, the Mylar film is in contact with the end face 321 of the convex portion 32 far away from the main body portion 31, and by reducing the contact area between the Mylar film and the surface of the main body portion 31 and by reducing the adaptability of the convex portion 32 to bending when tensile force is applied to the convex portion 32 by the Mylar film thermal shrinkage, the tensile force applied to the main body portion 31 by the Mylar film during thermal shrinkage is reduced, and further the tensile force applied to the packaging bag 100 by the Mylar film during thermal shrinkage is reduced.

In the packaging bag 100, there is a difference in height between the projection 32 and the surface of the main body 31 facing away from the metal layer 20 in the projecting direction of the projection 32. When the Mylar film wraps around the packaging bag 100, the Mylar film contacts the end 321 of the protrusion 32 remote from the body portion 31. Compared with a packaging bag with a completely planar outer surface, the contact area between the Mylar film and the surface of the main body part 31 is reduced, and therefore the tensile force of the Mylar film on the packaging bag 100 during heat shrinkage is 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 to discharge gas in bubbles generated between the packaging bag 100 and the Mylar film, so that the risk of appearance dent of the battery cell is reduced. In summary, the packaging bag 100 can improve the appearance yield of the battery cell when the Mylar film wraps the packaging 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 permeation into the interior of the cell, maintain the environment inside the package bag 100, and simultaneously improve the deformation capability of the package bag 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 interior of the 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 as to reduce the risk of moisture penetrating into the cell.

In some embodiments, the first polymer layer 10 is made of a polypropylene material. The first polymer layer 10 is melted at a predetermined temperature and has 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 packaging bag 100, reducing the risk of corrosion of the metal layer 20.

With continued reference to fig. 1 and 2, in some embodiments, each protrusion 32 has a first height H1 along the protruding direction of the protrusion 32, and the first height H1 is the highest height of the protrusion 32. It is understood that the end face 321 of each protrusion 32 away from the main body 31 may be a plane, a cambered surface, an irregular surface, or the like, and when the end face is a cambered surface or an irregular surface, a distance between an end of the cambered surface or the irregular surface farthest from the main body 31 and the main body 31 along the protruding direction of the protrusion 32 is the highest height of the protrusion 32.

The relationship between the first height H1 and the first thickness H2 of the main body portion 31 satisfies: h1 > 5 μm, H2 > 5 μm, and 0.5 < H1/H2 < 2, whereby each projection 32 can be stably supported on the main body 31. Thereby reducing the risk of the Mylar film coming into contact with the body portion 31 due to the lower protrusions 32 and reducing the risk of the protrusions 32 coming into transitional bending when in contact with the Mylar film due to the higher protrusions 32.

The relationship between the second thickness H3 of the metal layer 20 and the third thickness H4 of the first polymer layer 10 in the projecting direction of the projection 32 satisfies: h3 is more than 20 mu m, H4 is more than 10 mu m, H4/H3 is more than 0.2 and less than 2, the metal layer 20 can be improved to have excellent water-blocking capacity and structural strength, and the packaging bag 100 passing through the first polymer layer 10 is facilitated.

In some embodiments, the package 100 further includes adhesive layers (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 < 5 um.

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

When the Mylar film wraps the bag 100, the Mylar film contacts the end faces 321 of the protrusions 32 away from the body portion 31, and a channel 33 is formed between two adjacent protrusions 32 for gas to flow through. Specifically, the passage 33 includes a first branch 331 extending in the width direction of the main body 31 and a second branch 332 extending in the length direction of the main body 31, and the first branch 331 and the second branch 332 are communicated with each other in a crossing manner to form the two-dimensional passage 33, so that the gas can be easily discharged from between the packing bag 100 and the Mylar film.

In some embodiments, the end face 321 of the protrusion 32, which is away from the main body 31, is in a hemispherical shape to reduce a contact area between the Mylar film and the end face 321, so as to reduce an adhesive force between the Mylar film and the end face 321, and to facilitate reducing a pulling force on the packaging bag 100 when tearing off the Mylar film, so as to reduce a risk of appearance defects of the battery cell.

It will be appreciated 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 connecting surface 34 is provided between the protrusion 32 and the main body 31, i.e. a region of the surface of the main body 31 facing the protrusion 32, where the protrusion 32 is connected. The relationship between the first diameter D1 of the first cross-section and the first distance L1 between two adjacent first cross-sections at the first connecting surface 34 and along the width direction of the package 100 (e.g., the first direction a as described below) is satisfied: d1 > 100 μm, L1/D1 > 0.1, and it is possible to arrange the adjacent two projections 32 at intervals to form the channel 33.

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

Referring also to fig. 3, in some embodiments, the relationship between the first diameter D1 of the first cross-sections 322 and the first center-to-center distance D1 between two adjacent first cross-sections 322 at the first connecting surface 34 and along the length direction of the package 100 (e.g., the second direction B as described below) is satisfied: d1 is more than 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 projections 32 are spaced apart to form the passage 33. By setting the ratio of the first diameter D1 to the first center-to-center distance D1 to D1/D1 < 5, the risk of the Mylar film not being stabilized due to too long a distance between two adjacent protrusions 32 is reduced, and the risk of the Mylar film contacting the main body portion 31 is reduced.

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

Referring to fig. 1 and 4, in some embodiments, the second cross-section 323 of each protrusion 32 is rectangular in a direction perpendicular to the protruding direction of the protrusion 32, i.e., the protrusion 32 may have a rectangular shape or a truncated pyramid 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 main body 31 is provided on a surface thereof with a plurality of sets of protrusions 32a arranged at intervals in the first direction a, and each set of protrusions 32a includes a plurality of protrusions 32 arranged in the second direction B.

When the Mylar film wraps the bag 100, the Mylar film contacts the end faces 321 of the protrusions 32 away from the body portion 31, and a channel 33 is formed between two adjacent protrusions 32 for gas to flow through. Specifically, the channel 33 includes a first branch 331 extending along the first direction a and a second branch 332 extending along 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, so as to facilitate the escape of gas between the packaging bag 100 and the Mylar film.

In some embodiments, the end face 321 of the protrusion 32, which is far away from the main body 31, is an arc-shaped face, so as to reduce a contact area between the Mylar film and the end face 321, further reduce an adhesive force between the Mylar film and the end face 321, and facilitate reducing a pulling force on the packaging bag 100 when tearing off the Mylar film, so as to reduce a risk of appearance defects of the battery cell. In some embodiments, the profile of the end face 321 extends in a circular arc, viewed in the second direction B.

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

In some embodiments, the first direction a is disposed in the same direction as the width direction of the body portion 31; the second direction B is provided in the same direction as the longitudinal direction of the body 31.

It is understood that in other embodiments, the first direction a is disposed in the same direction as the length direction of the main body portion 31; the second direction B is provided in the same direction as the width direction of the body 31.

It is understood 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 inclined to the width direction of the main body 31.

With continued reference to fig. 4, in some embodiments, at the first connecting surface 34, 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.

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

In some embodiments, on the first connecting face 34, along the first direction a, a relationship between a second distance L2 between the centerlines a1 of two adjacent second sections 323 and a first width W1 of the second sections 323 satisfies: w1 is more than 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 projections 32 are spaced apart to form the channel 33. By setting the ratio between the first width W1 and the second pitch L2 to L2/W1 < 4, the risk of the Mylar film not being stabilized due to too long a pitch between two adjacent protrusions 32 is reduced, and the risk of the Mylar film coming into contact with the main body portion 31 is reduced.

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

In some embodiments, on the first connection face 34, along the second direction B, a relationship between a third distance L4 between two adjacent second cross sections 323 and the first length L3 of the second cross sections 323 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 projections 32 are spaced apart to form the channel 33. By setting the ratio between the first width W1 and the third pitch L4 to L4/L3 < 2, the risk of the Mylar film coming into contact with the main body portion 31 is reduced.

In some embodiments, L4/L3 may take on one of the values 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 body 31 facing away from the metal layer 20. The third cross section 351 of each projection 35 is circular in shape in a direction perpendicular to the projecting direction of the projection 32, i.e., the projection 32 may be cylindrical or truncated cone-shaped.

In each of the convex portion groups 32a, at least one convex portion 35 is disposed between two adjacent convex portions 32. When the Mylar film wraps around the package 100, the Mylar film contacts the end 321 of the projection 32 remote from the body portion 31 and the end of the tab 35 remote from the body portion 31. Channels 33 are formed between adjacent projections 32 and projections 35 for gas communication.

Referring to fig. 1 and 6, in some embodiments, the shape of the fourth cross section 324 of each protrusion 32 is rectangular along the direction perpendicular to the protruding direction of the protrusion 32, i.e., the protrusion 32 may be rectangular or truncated. The width direction of the fourth cross section 324 is defined as the third direction C, and the length direction of the fourth cross 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 two ends of each protrusion 32 along the fourth direction D are flush with corresponding edges of the main body 31.

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

In some embodiments, the end face 321 of the protrusion 32, which is far away from the main body 31, is an arc-shaped face, so as to reduce a contact area between the Mylar film and the end face 321, further reduce an adhesive force between the Mylar film and the end face 321, and facilitate reducing a pulling force on the packaging bag 100 when tearing off the Mylar film, so as to reduce a risk of appearance defects of the battery cell. In some embodiments, the profile of the end surface 321 extends in a circular arc shape, 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; the fourth direction D is provided in the same direction as the longitudinal direction of the body 31.

It is understood that in other embodiments, the third direction C is disposed in the same direction as the longitudinal direction of the main body portion 31; the fourth direction D is provided in the same direction as the width direction of the body 31.

It is understood 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 inclined to the width direction of the body portion 31.

In some embodiments, on the first connecting face 34, along the third direction C, a relationship between a fourth spacing L5 between the center lines a2 of two adjacent fourth cross sections 324 and a second width W2 of the fourth cross sections 324 satisfies: w2 > 100 μm, L5/W2 > 1, and it is possible to arrange the interval between two adjacent projections 32 to form the channel 33.

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

It will be appreciated that in some embodiments, each protrusion 32 may also have a cross-section in a direction perpendicular to the direction of protrusion of the protrusion 32 that is one of square, triangular, polygonal, irregular, and the like.

It will be appreciated that in some embodiments, a pre-cut is provided between the protrusion 32 and the body portion 31, and that the protrusion 32 will separate from the body portion 31 by the adhesive action of the Mylar film when the Mylar film is removed, thereby flattening the outer side of the second polymer layer 30.

Referring to fig. 7, an embodiment of the present application provides a battery cell 200 including an electrode assembly (not shown). The battery cell 200 further includes any of the packaging bags 100 in the above embodiments, and the electrode assembly is housed in the packaging bag 100 and may be opposed 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 bag 100. The first tab 91 and the second tab 92 are disposed on the same side.

In the packaging bag 100 and the battery cell 200 provided with the packaging bag 100, there is a difference in height between the protrusion 32 and the surface of the body 31 facing away from the metal layer 20 in the protruding direction of the protrusion 32. When the Mylar film wraps around the packaging bag 100, the Mylar film contacts the end 321 of the protrusion 32 remote from the body portion 31. Compared with a packaging bag with a completely planar outer surface, the contact area between the Mylar film and the surface of the main body part 31 is reduced, and therefore the tensile force of the Mylar film on the packaging bag 100 during heat shrinkage is 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 to discharge gas in bubbles generated between the packaging bag 100 and the Mylar film, so that the risk of appearance dent of the battery cell is reduced. In summary, the packaging bag 100 can improve the appearance yield of the battery cell when the Mylar film wraps the packaging bag 100.

In addition, other changes may be made by those skilled in the art within the spirit of the present application, and it is understood that such changes are encompassed within the scope of the present disclosure.

Claims

1. The utility model provides a packaging bag, includes by interior first polymer layer, metal level and the second polymer layer that sets gradually outward, its characterized in that: the second polymer layer comprises a main body part and a plurality of convex parts arranged at intervals, the convex parts are arranged on the surface of the main body part deviating from the metal layer, and a channel is formed between every two adjacent convex parts to allow gas to circulate.

2. The package of claim 1, wherein: the first cross section of each of the protrusions is circular in shape in a direction perpendicular to a protruding direction of the protrusion.

3. The package of claim 2, wherein: a first connecting 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 distance D1 between two adjacent first cross sections at the first connecting surface and in a width direction of the packaging bag satisfies: d1 is more than 100 μm, 1 < D1/D1 < 5.

4. The package of claim 2, wherein: a first connecting 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 pitch L1 between two adjacent first cross sections at the first connecting surface and along the length direction of the packaging bag satisfies: d1 > 100 μm, L1/D1 > 0.1.

5. The package of claim 1, wherein: the main body part surface is provided with a plurality of groups of convex parts which are arranged along the first direction at intervals, and each group of convex parts comprises a plurality of convex parts which are arranged along the second direction.

6. The package of claim 5, wherein: a first connection surface is provided between the convex portion and the main body portion, and a relationship between a first width W1 of the second cross section and a first length L3 of the second cross section on the first connection surface satisfies: L3/W1> 2.

7. The package of claim 5, wherein: a first connecting surface is provided between the convex portion and the main body portion, and a relationship between a second pitch L2 between adjacent second section center lines and a first width W1 of the second section in the first direction on the first connecting surface satisfies: w1 is more than 100 μm, 1 < L2/W1 < 4.

8. The package of claim 5, wherein: a first connecting 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 section in the second direction on the first connecting surface satisfies: 0.1 < L4/L3 < 2.

9. The package of claim 5, wherein: the second polymer layer further comprises a plurality of bumps, the bumps are arranged on the surface, deviating from the metal layer, of the main body part, the shape of the third section of each bump is circular along the direction perpendicular to the protruding direction of the convex part, and in each group of convex parts, at least one bump is arranged between every two adjacent convex parts.

10. The package of claim 1, wherein: the edge with the direction of protrusion vertically of convex part, each the shape of the fourth cross-section of convex part is the rectangle, defines the width direction of fourth cross-section is the third direction, the length direction of fourth cross-section is the fourth direction, the main part surface is provided with the edge a plurality of convex parts of third direction interval arrangement, each the convex part along the both ends of fourth direction with the edge parallel and level that the main part corresponds sets up.

11. The package of claim 10, wherein: a first connecting surface is provided between the convex portion and the main body portion, and a relationship between a fourth pitch L5 between adjacent two fourth section center lines and a second width W2 of the fourth section in the third direction on the first connecting surface satisfies: l5 > 100 μm, L5/W2 > 1.

12. The package of claim 1, wherein: in the projection direction of the projections, each of the projections has a first height H1, a first height H1 is the highest height of the projection, and the relationship between the first height H1 and the first thickness H2 of the main body portion satisfies: h1 is more than 5 μm, H2 is more than 5 μm, H1/H2 is more than 0.5 and less than 2.

13. The package of claim 1, wherein: the relationship between the second thickness H3 of the metal layer and the third thickness H4 of the first polymer layer in the projection direction of the projections satisfies: h3 is more than 20 μm, H4 is more than 10 μm, H4/H3 is more than 0.2 and less than 2.

14. A cell comprising an electrode assembly, wherein: the cell further comprising a package of any of claims 1 to 13, the electrode assembly being contained within the package.