Packaging bags and battery cells

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

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a packaging bag and a battery cell. Background Art

[0002] Mylar film is a polyester film with the characteristics of high surface flatness, good transparency, chemical corrosion resistance and good flexibility. In the production process of batteries, Mylar film is often used to wrap the battery cells, which can effectively and reliably seal and protect the battery cells.

[0003] The outer surface of the conventional battery cell packaging bag is flat and fits tightly with the Mylar film. In a vacuum and high temperature environment, the Mylar film shrinks and causes the outer surface of the packaging bag to be stretched and deformed, resulting in a poor appearance of the battery cell. In addition, bubbles are likely to appear during the process of attaching the Mylar film to the outer surface of the packaging bag, and local pits appear in the battery cell during the pressure process, affecting the appearance of the battery cell. In summary, the existing battery cell is prone to poor appearance when attached with the Mylar film. Summary of the invention

[0004] In view of the above situation, it is necessary to provide a packaging bag that can improve the appearance yield of the battery cell when the packaging bag is wrapped with a Mylar film.

[0005] The embodiment of the present application provides 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. The second polymer layer comprises a main body and a plurality of convex portions arranged at intervals, the convex portions are arranged on the surface of the main body away from the metal layer, and a channel is formed between two adjacent convex portions for gas circulation.

[0006] Due to the height difference between the surface of the protrusion and the main body away from the metal layer along the protruding direction of the protrusion. When the Mylar film is wrapped around the packaging bag, the Mylar film contacts the end face of the protrusion away from the main body. Compared with a packaging bag whose outer surface is completely flat, the contact area between the Mylar film and the surface of the main body is reduced, thereby reducing the pulling force on the packaging bag when the Mylar film shrinks. When the packaging bag is used to package battery cells, the embodiments of the present application can reduce the risk of poor appearance of the battery cells due to thermal shrinkage of the Mylar film. In addition, a channel is formed between two adjacent protrusions for gas circulation, which can discharge the gas in the bubbles generated between the packaging bag and the Mylar film to reduce the risk of appearance dents on the battery cells. In summary, the above-mentioned packaging bag can improve the appearance yield of the battery cells when the packaging bag is wrapped with Mylar film.

[0007] In some embodiments of the present application, along a direction perpendicular to the protruding direction of the protrusion, the shape of the first cross-section of each protrusion is circular, so that the channel includes a first branch extending along the width direction of the main body and a second branch extending along the length direction of the main body, and the first branch and the second branch are cross-connected to form a two-dimensional channel to facilitate the escape of gas from between the packaging bag and the Mylar film.

[0008] In some embodiments of the present application, a first connecting surface is provided between the convex portion and the main body portion, and 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. By setting the ratio between the first diameter D1 and the first center distance d1 to d1 / D1>1, two adjacent convex portions are spaced to form a channel. By setting the ratio between the first diameter D1 and the first center distance d1 to d1 / D1<5, the risk of the Mylar film being unable to be stabilized due to the excessively long spacing between two adjacent convex portions is reduced, thereby reducing the risk of the Mylar film contacting the main body portion.

[0009] In some embodiments of the present application, a first connecting surface is provided between the protrusion and the main body, and 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 spacing L1 between two adjacent first cross-sections satisfies: D1>100μm, L1 / D1>0.1, so that two adjacent protrusions can be spaced apart to form a channel.

[0010] In some embodiments of the present application, 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, and the length direction of the second cross section is defined as the second direction. The surface of the main body is provided with a plurality of groups of protrusions arranged at intervals along the first direction, and each group of protrusions includes a plurality of protrusions arranged along the second direction, so that the channel includes a first branch extending along the first direction and a second branch extending along the second direction, and the first branch and the second branch are intersected and connected to form a two-dimensional channel, so that the gas can escape from between the packaging bag and the Mylar film.

[0011] In some embodiments of the present application, 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.

[0012] In some embodiments of the present application, a first connecting surface is provided between the protrusion and the main body, and 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. By setting the ratio between the first width W1 and the second spacing L2 to L2 / W1>1, the two adjacent protrusions are spaced 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 the Mylar film being unable to be stabilized due to the excessively long spacing between the two adjacent protrusions is reduced, thereby reducing the risk of the Mylar film contacting the main body.

[0013] In some embodiments of the present application, a first connecting surface is provided between the convex portion and the main body portion, and 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. By setting the ratio between the first width W1 and the third spacing L4 to L4 / L3>0.1, the two adjacent convex portions are spaced 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 the Mylar film contacting the main body portion is reduced.

[0014] In some embodiments of the present application, the second polymer layer further includes a plurality of bumps, which are arranged on the surface of the main body away from the metal layer, and along the direction perpendicular to the protruding direction of the convex portion, the shape of the third cross section of each bump is circular, and in each group of convex portions, at least one bump is arranged between two adjacent convex portions. When the Mylar film wraps the packaging bag, the Mylar film contacts the end surface of the convex portion away from the main body, and the end of the convex portion away from the main body. A channel is formed between the adjacent convex portions and the bumps for gas circulation.

[0015] In some embodiments of the present application, along the direction perpendicular to the protruding direction of the protrusion, the shape of the fourth cross section of each protrusion is rectangular, 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 is provided with a plurality of protrusions arranged at intervals along the third direction, and both ends of each protrusion along the fourth direction are arranged flush with the corresponding edge of the main body, so that a one-dimensional channel extending along the fourth direction is formed between two adjacent protrusions, thereby facilitating the escape of gas from between the packaging bag and the Mylar film.

[0016] In some embodiments of the present application, a first connecting surface is provided between the protrusion and the main body. 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, which enables the two adjacent protrusions to be spaced apart to form a channel.

[0017] In some embodiments of the present application, along the protruding direction of the protrusion, each protrusion 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

[0018] In some embodiments of the present application, along the protruding direction of the convex portion, 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, so that the metal layer has excellent water-blocking ability and structural strength, and is convenient for the packaging bag to pass through the first polymer layer.

[0019] An embodiment of the present application further provides a battery cell, including an electrode assembly. The battery cell further includes any one of the packaging bags in the above embodiments, wherein the electrode assembly is accommodated in the packaging bag, and the first polymer layer of the packaging bag is opposite to the electrode assembly.

[0020] In the packaging bag of the present application and the battery cell provided with the packaging bag, there is a height difference between the surface of the protrusion and the main body away from the metal layer due to the protruding direction of the protrusion. When the Mylar film is wrapped around the packaging bag, the Mylar film contacts the end face of the protrusion away from the main body. Compared with the packaging bag whose outer surface is completely planar, the contact area between the Mylar film and the surface of the main body is reduced, thereby reducing the pulling force on the packaging bag when the Mylar film shrinks thermally. When the packaging bag is used to package the battery cell, the embodiment of the present application can reduce the risk of the battery cell having poor appearance due to the thermal shrinkage of the Mylar film. In addition, a channel is formed between two adjacent protrusions for gas circulation, which can discharge the gas in the bubbles generated between the packaging bag and the Mylar film to reduce the risk of appearance dents on the battery cell. In summary, the above-mentioned packaging bag can improve the appearance yield of the battery cell when the packaging bag is wrapped with Mylar film. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the structure of a packaging bag according to an embodiment of the present application.

[0022] Figure 2 It is a first top view structural schematic diagram of a packaging bag of an embodiment of the present application.

[0023] Figure 3 It is a second top view structural schematic diagram of a packaging bag of an embodiment of the present application.

[0024] Figure 4 ​It is a third top view structural schematic diagram of a packaging bag according to an embodiment of the present application.

[0025] Figure 5 It is a fourth top view structural schematic diagram of a packaging bag according to an embodiment of the present application.

[0026] Figure 6 It is a fifth top view structural schematic diagram of a packaging bag according to an embodiment of the present application.

[0027] Figure 7 It is a schematic diagram of the structure of a battery cell according to an embodiment of the present application.

[0028] Main component symbols

[0029] Packaging bag 100

[0030] Battery Cell 200

[0031] First polymer layer 10

[0032] Metal layer 20

[0033] Second polymer layer 30

[0034] Main body 31

[0035] Projection 32

[0036] End face 321

[0037] First section 322

[0038] Second section 323

[0039] Fourth Section 324

[0040] Protrusion group 32a

[0041] Channel 33

[0042] 331 First Branch Road

[0043] Second Branch Road 332

[0044] First connecting surface 34

[0045] Bump 35

[0046] First tab 91

[0047] Second pole ear 92

[0048] First direction A

[0049] Second direction B

[0050] The third direction C

[0051] Fourth direction D

[0052] Center lines A1, A2

[0053] First diameter D1

[0054] The first distance L1

[0055] The first circle center distance d1

[0056] First width W1

[0057] The second distance L2

[0058] First length L3

[0059] The third distance L4

[0060] The second width W2

[0061] Fourth distance L5

[0062] First height H1

[0063] First thickness H2

[0064] The second thickness H3

[0065] The third thickness H4

[0066] The following specific implementation methods will further illustrate the present application in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0067] The technical solutions in the embodiments of the present application will be described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments.

[0068] It should be noted that when an element is considered to be "connected" to another element, it may be directly connected to the other element or there may be a centrally disposed element at the same time. When an element is considered to be "disposed on" another element, it may be directly disposed on the other element or there may be a centrally disposed element at the same time.

[0069] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art belonging to the technical field of the present application. The terms used herein in the specification of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application. The term "and / or" used herein includes any and all combinations of one or more related listed items. The terms "vertical", "horizontal", "left", "right", "top", "bottom" and similar expressions used herein are only for illustrative purposes and are not intended to limit the present application.

[0070] It can be understood that when two elements are arranged parallel / vertically and in the same direction, there may be a certain angle between the two elements, a tolerance of 0-±10% is allowed between the two elements, and a tolerance of 0-±10% is allowed between the two elements greater than, equal to or less than.

[0071] The embodiment of the present application provides 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. The second polymer layer comprises a main body and a plurality of convex portions arranged at intervals, the convex portions are arranged on the surface of the main body away from the metal layer, and a channel is formed between two adjacent convex portions for gas circulation.

[0072] In the above-mentioned packaging bag, there is a height difference between the surface of the protrusion and the main body away from the metal layer due to the protruding direction of the protrusion. When the Mylar film is wrapped around the packaging bag, the Mylar film contacts the end face of the protrusion away from the main body. Compared with a packaging bag whose outer surface is completely planar, the contact area between the Mylar film and the surface of the main body is reduced, thereby reducing the pulling force on the packaging bag when the Mylar film shrinks thermally. When the packaging bag is used to package battery cells, the embodiments of the present application can reduce the risk of poor appearance of the battery cells due to thermal shrinkage of the Mylar film. In addition, a channel is formed between two adjacent protrusions for gas circulation, which can discharge the gas in the bubbles generated between the packaging bag and the Mylar film to reduce the risk of appearance dents on the battery cells. In summary, the above-mentioned packaging bag can improve the appearance yield of the battery cells when the packaging bag is wrapped with Mylar film.

[0073] The embodiments of the present application are further described with reference to the accompanying drawings.

[0074] Please also read Figure 1 and Figure 2 One embodiment of the present application provides a packaging bag 100, comprising a first polymer layer 10, a metal layer 20 and a second polymer layer 30 arranged in sequence from the inside to the outside.

[0075] The second polymer layer 30 includes a main body 31 and a plurality of convex portions 32 arranged at intervals. The convex portions 32 are disposed on a surface of the main body 31 away from the metal layer 20 , and a channel 33 is formed between two adjacent convex portions 32 for gas flow.

[0076] When the Mylar film wraps the packaging bag 100, the Mylar film contacts the end surface 321 of the protrusion 32 away from the main body 31. By reducing the contact area between the Mylar film and the surface of the main body 31 and the protrusion 32 being able to bend adaptively when the Mylar film thermally shrinks and applies tension to the protrusion 32, the tension of the Mylar film on the main body 31 is reduced, thereby reducing the tension of the Mylar film on the packaging bag 100 when the Mylar film thermally shrinks.

[0077] In the above packaging bag 100, there is a height difference between the surface of the protrusion 32 and the surface of the main body 31 away from the metal layer 20 along the protruding direction of the protrusion 32. When the Mylar film is wrapped around the packaging bag 100, the Mylar film contacts the end surface 321 of the protrusion 32 away from the main body 31. Compared with a packaging bag whose outer surface is completely flat, the contact area between the Mylar film and the surface of the main body 31 is reduced, thereby reducing the pulling force on the packaging bag 100 when the Mylar film shrinks thermally. When the packaging bag 100 is used to package a battery cell, the risk of the battery cell having a poor appearance due to the thermal shrinkage of the Mylar film can be reduced. In addition, a channel is formed between two adjacent protrusions 32 for gas circulation, which is used to discharge the gas in the bubbles generated between the packaging bag 100 and the Mylar film, so as to reduce the risk of the battery cell having an appearance dent. In summary, the above packaging bag 100 can improve the appearance yield of the battery cell when the packaging bag 100 is wrapped with the Mylar film.

[0078] In some embodiments, the second polymer layer 30 is made of nylon material. The second polymer layer 30 is used to reduce the risk of air penetrating into the battery cell, maintain the environment inside the packaging bag 100, and improve the deformation ability of the packaging bag 100.

[0079] In some embodiments, the metal layer 20 is made of aluminum material. The metal layer 20 is used to reduce the risk of water vapor penetrating into the battery cell and improve the structural strength of the packaging bag 100. Specifically, the aluminum material reacts with oxygen in the air to form a dense oxide film to reduce the risk of water vapor penetrating into the battery cell.

[0080] In some embodiments, the first polymer layer 10 is made of a polypropylene material. The first polymer layer 10 melts at a preset temperature and has viscosity to facilitate packaging of the packaging bag 100. In addition, the polypropylene material will not be dissolved or swelled by an organic solvent (such as an electrolyte) in the packaging bag 100, thereby reducing the risk of corrosion of the metal layer 20.

[0081] Please continue reading Figure 1 and Figure 2 In some embodiments, along the protruding direction of the protrusion 32, each protrusion 32 has a first height H1, and the first height H1 is the highest height of the protrusion 32. It can be understood that the end surface 321 of each protrusion 32 away from the main body 31 can be a plane, a curved surface or an irregular surface, etc. When it is a curved surface or an irregular surface, along the protruding direction of the protrusion 32, the distance between the end of the curved surface or irregular surface farthest from the main body 31 and the main body 31 is the highest height of the protrusion 32.

[0082] The relationship between the first height H1 and the first thickness H2 of the main body 31 satisfies: H1>5μm, H2>5μm, 0.5

[0083] Along the protruding direction of the 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 satisfies: H3>20μm, H4>10μm, 0.2<H4 / H3<2, which can enhance the excellent water-blocking ability and structural strength of the metal layer 20 and facilitate the packaging bag 100 passing through the first polymer layer 10.

[0084] In some embodiments, the packaging bag 100 further includes an adhesive layer (not shown), which is disposed between the first polymer layer 10 and the metal layer 20, and between the metal layer 20 and the second polymer layer 30, so as 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 packaging bag 100. In some embodiments, the thickness of the adhesive layer is less than 5 um.

[0085] Please continue reading Figure 1 and Figure 2 In some embodiments, along a direction perpendicular to the protruding direction of the protrusion 32 , the shape of the first cross section 322 of each protrusion 32 is circular, that is, the protrusion 32 may be cylindrical or truncated cone-shaped.

[0086] When the Mylar film wraps the packaging bag 100, the Mylar film contacts the end surface 321 of the protrusion 32 away from the main body 31, and a channel 33 is formed between two adjacent protrusions 32 for gas circulation. 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. The first branch 331 and the second branch 332 cross and communicate with each other to form a two-dimensional channel 33, so that the gas can escape from between the packaging bag 100 and the Mylar film.

[0087] In some embodiments, the end surface 321 of the protrusion 32 away from the main body 31 is in a hemispherical shape to reduce the contact area between the Mylar film and the end surface 321, thereby reducing the adhesion between the Mylar film and the end surface 321, making it easier to reduce the pulling force on the packaging bag 100 when tearing off the Mylar film, thereby reducing the risk of poor appearance of the battery cell.

[0088] It can be understood that, in some embodiments, the end surface 321 can be a plane, a curved surface, an irregular surface, etc. ​

[0089] Please continue reading Figure 2 In some embodiments, a first connection surface 34 is provided between the protrusion 32 and the main body 31, that is, a region on the surface of the main body 31 facing the protrusion 32 that is connected to the protrusion 32. On the first connection surface 34 and along the width direction of the packaging bag 100 (such as the first direction A described below), the relationship between the first diameter D1 of the first cross section and the first spacing L1 between two adjacent first cross sections satisfies: D1>100μm, L1 / D1>0.1, so that two adjacent protrusions 32 can be spaced to form a channel 33.

[0090] In some embodiments, L1 / D1 can take a value of 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, etc.

[0091] Please also read Figure 3 In some embodiments, on the first connecting surface 34 and along the length direction of the packaging bag 100 (such as the second direction B described below), the relationship between the first diameter D1 of the first section 322 and the first center distance d1 between two adjacent first sections 322 satisfies: D1>100μm, 1<d1 / D1<5.

[0092] By setting the ratio between the first diameter D1 and the first center distance d1 to d1 / D1>1, two adjacent protrusions 32 are spaced apart to form a channel 33. By setting the ratio between the first diameter D1 and the first center distance d1 to d1 / D1<5, the risk of the Mylar film being unable to be stabilized due to the excessively long spacing between the two adjacent protrusions 32 is reduced, thereby reducing the risk of the Mylar film contacting the main body 31.

[0093] In some embodiments, d1 / D1 may take a value of 1.5, 2, 2.5, 3, 3.5, 4, 4.5, etc.

[0094] Please also read Figure 1 and Figure 4 In some embodiments, along the direction perpendicular to the protruding direction of the protrusion 32, the second cross section 323 of each protrusion 32 is rectangular, that is, the protrusion 32 can be in the shape of a cuboid or a prism. The width direction of the second cross section 323 is defined as the first direction A, and the length direction of the second cross section 323 is defined as the second direction B. The surface of the main body 31 is provided with a plurality of groups of protrusions 32a arranged at intervals along the first direction A, and each group of protrusions 32a includes a plurality of protrusions 32 arranged along the second direction B.

[0095] When the Mylar film wraps the packaging bag 100, the Mylar film contacts the end surface 321 of the protrusion 32 away from the main body 31, and a channel 33 is formed between two adjacent protrusions 32 for gas circulation. 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. The first branch 331 and the second branch 332 cross and communicate with each other to form a two-dimensional channel 33, so that the gas can escape from between the packaging bag 100 and the Mylar film.

[0096] In some embodiments, the end surface 321 of the convex portion 32 away from the main body portion 31 is an arc-shaped surface to reduce the contact area between the Mylar film and the end surface 321, thereby reducing the adhesion between the Mylar film and the end surface 321, which is convenient for reducing the pulling force on the packaging bag 100 when the Mylar film is torn off, thereby reducing the risk of poor appearance of the battery cell. In some embodiments, when viewed along the second direction B, the contour of the end surface 321 extends in an arc shape.

[0097] It can be understood that, in some embodiments, the end surface 321 can be a plane or an irregular surface.

[0098] In some embodiments, the first direction A is arranged in the same direction as the width direction of the main body 31 ; and the second direction B is arranged in the same direction as the length direction of the main body 31 .

[0099] It can be understood that, in other embodiments, the first direction A is arranged in the same direction as the length direction of the main body 31 ; and the second direction B is arranged in the same direction as the width direction of the main body 31 .

[0100] It can be understood that, in other embodiments, the first direction A is inclined relative to the width direction of the main body 31 ; and / or the second direction B is inclined relative to the width direction of the main body 31 .

[0101] Please continue reading Figure 4 In some embodiments, on the first connecting surface 34 , the relationship between the first width W1 of the second cross section 323 and the first length L3 of the second cross section 323 satisfies: L3 / W1>2.

[0102] In some embodiments, L3 / W1 can take a value of 2, 3, 4, 5, 6, 7, 8, etc.

[0103] In some embodiments, on the first connecting surface 34 , along the first direction A, the relationship between the second spacing L2 between the center lines A1 of two adjacent second sections 323 and the first width W1 of the second section 323 satisfies: W1>100 μm, 1<L2 / W1<4.

[0104] By setting the ratio between the first width W1 and the second spacing L2 to L2 / W1>1, two adjacent protrusions 32 are spaced apart to form a channel 33. By setting the ratio between the first width W1 and the second spacing L2 to L2 / W1<4, the risk of the Mylar film being unable to be stabilized due to the excessively long spacing between two adjacent protrusions 32 is reduced, thereby reducing the risk of the Mylar film contacting the main body 31.

[0105] In some embodiments, L2 / W1 may take a value of 1.5, 2, 2.5, 3, 3.5, etc.

[0106] In some embodiments, on the first connecting surface 34 , along the second direction B, the relationship between the third interval L4 between two adjacent second cross sections 323 and the first length L3 of the second cross section 323 satisfies: 0.1<L4 / L3<2.

[0107] By setting the ratio between the first width W1 and the third spacing L4 to L4 / L3>0.1, two adjacent protrusions 32 are spaced apart to form a channel 33. By setting the ratio between the first width W1 and the third spacing L4 to L4 / L3<2, the risk of the Mylar film contacting the main body 31 is reduced.

[0108] In some embodiments, L4 / L3 can take a value of 0.2, 0.4, 0.6, 0.8, 1, 1.2, 1.4, 1.6, 1.8, etc.

[0109] Please also read Figure 5 In some embodiments, the second polymer layer 30 further includes a plurality of bumps 35, which are disposed on a surface of the main body 31 away from the metal layer 20. Along a direction perpendicular to the protruding direction of the protrusion 32, the shape of the third cross section 351 of each bump 35 is circular, that is, the protrusion 32 may be cylindrical or truncated cone-shaped.

[0110] In each group of protrusions 32a, at least one protrusion 35 is provided between two adjacent protrusions 32. When the Mylar film wraps the packaging bag 100, the Mylar film contacts the end surface 321 of the protrusion 32 away from the main body 31 and the end of the protrusion 35 away from the main body 31. A channel 33 is formed between adjacent protrusions 32 and protrusions 35 for gas circulation.

[0111] Please also read Figure 1 and Figure 6In some embodiments, along the direction perpendicular to the protruding direction of the protrusion 32, the shape of the fourth cross section 324 of each protrusion 32 is rectangular, that is, the protrusion 32 can be in the shape of a cuboid or a prism. 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 both ends of each protrusion 32 along the fourth direction D are arranged flush with the corresponding edge of the main body 31.

[0112] When the Mylar film wraps the packaging 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 along the fourth direction D is formed between two adjacent protrusions 32 for gas circulation, thereby facilitating the gas to escape from between the packaging bag 100 and the Mylar film.

[0113] In some embodiments, the end surface 321 of the convex portion 32 away from the main body portion 31 is an arc-shaped surface to reduce the contact area between the Mylar film and the end surface 321, thereby reducing the adhesion between the Mylar film and the end surface 321, which is convenient for reducing the pulling force on the packaging bag 100 when the Mylar film is torn off, thereby reducing the risk of poor appearance of the battery cell. In some embodiments, when viewed along the fourth direction D, the contour of the end surface 321 extends in an arc shape.

[0114] It can be understood that, in some embodiments, the end surface 321 can be a plane or an irregular surface.

[0115] In some embodiments, the third direction C is arranged in the same direction as the width direction of the main body 31 ; and the fourth direction D is arranged in the same direction as the length direction of the main body 31 .

[0116] It can be understood that, in other embodiments, the third direction C is set in the same direction as the length direction of the main body 31 ; and the fourth direction D is set in the same direction as the width direction of the main body 31 .

[0117] It can be understood that, in other embodiments, the third direction C is arranged to be inclined relative to the width direction of the main body 31 ; and / or the fourth direction D is arranged to be inclined relative to the width direction of the main body 31 .

[0118] In some embodiments, on the first connecting surface 34 , along the third direction C, the relationship between the fourth spacing L5 between the center lines A2 of two adjacent fourth sections 324 and the second width W2 of the fourth section 324 satisfies: W2>100μm, L5 / W2>1, which enables the two adjacent protrusions 32 to be spaced apart to form a channel 33.

[0119] In some embodiments, L5 / W2 can take a value of 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, etc.

[0120] It can be understood that, in some embodiments, along a direction perpendicular to the protruding direction of the protrusion 32 , the cross-section of each protrusion 32 can also be one of square, triangle, polygonal and irregular shapes.

[0121] It is understandable that in some embodiments, a pre-section is provided between the protrusion 32 and the main body 31 , and when the Mylar film is torn off, the protrusion 32 is separated from the main body 31 due to the bonding effect of the Mylar film, thereby making the outer side of the second polymer layer 30 flat.

[0122] See also Figure 7 One embodiment of the present application provides a battery cell 200 including an electrode assembly (not shown). The battery cell 200 further includes any packaging bag 100 in the above embodiments, and the electrode assembly is contained in the packaging bag 100 and can be opposite to the first polymer layer 10 .

[0123] In some embodiments, the battery cell 200 further includes a first pole tab 91 and a second pole tab 92, one of the first pole tab 91 and the second pole tab 92 being a positive pole tab and the other being a negative pole tab. One end of the first pole tab 91 is connected to the electrode assembly, and the other end extends out of the packaging bag 100. One end of the second pole tab 92 is connected to the electrode assembly, and the other end extends out of the packaging bag 100. The first pole tab 91 and the second pole tab 92 are arranged on the same side.

[0124] In the packaging bag 100 and the battery cell 200 provided with the packaging bag 100, there is a height difference between the surface of the protrusion 32 and the main body 31 away from the metal layer 20 along the protruding direction of the protrusion 32. When the Mylar film wraps the packaging bag 100, the Mylar film contacts the end surface 321 of the protrusion 32 away from the main body 31. Compared with the packaging bag whose outer surface is completely flat, the contact area between the Mylar film and the surface of the main body 31 is reduced, thereby reducing the tension of the Mylar film on the packaging bag 100 when the Mylar film shrinks. When the packaging bag 100 is used to package the battery cell, the risk of the battery cell having a poor appearance due to the thermal shrinkage of the Mylar film can be reduced. In addition, a channel is formed between two adjacent protrusions 32 for gas circulation, which is used to discharge the gas in the bubbles generated between the packaging bag 100 and the Mylar film, so as to reduce the risk of the battery cell having an appearance dent. In summary, the packaging bag 100 can improve the appearance yield of the battery cell when the packaging bag 100 is wrapped with the Mylar film.

[0125] In addition, those skilled in the art may also make other changes within the spirit of the present application. Of course, these changes made according to the spirit of the present application should be included in the scope disclosed in the present application.

Claims

1. A packaging bag, comprising a first polymer layer, a metal layer and a second polymer layer arranged in sequence from inside to outside, characterized in that: The second polymer layer comprises a main body and a plurality of convex parts arranged at intervals, wherein the convex parts are arranged on a surface of the main body away from the metal layer, and a channel is formed between two adjacent convex parts for gas flow; 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 protrusions are arranged along the second direction to form a protrusion group, a plurality of 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 according to claim 1, characterized in that: When the second cross-section of each protrusion 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 according to claim 1, 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, which 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 according to claim 1, characterized in that: Along the direction perpendicular to the protruding direction of the protrusion, the shape of the fourth cross-section of each protrusion 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 protrusion along the fourth direction are flush with the corresponding edge of the main body.

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

6. The packaging bag according to claim 1, characterized in that: Along the protruding direction of the protrusions, each of the protrusions has a first height H1, which is the highest height of the protrusions. 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>20 μm, H4>10 μm, 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, characterized in that: The battery cell further includes a Mylar film, and the Mylar film is in contact with an end surface of the protrusion away from the main body.

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