Single battery, battery, electric equipment and battery processing device

Abstract

The utility model relates to the technical field of batteries, and provides a single battery, a battery, electric equipment and a battery processing device. Each single battery comprises a shell and a battery cell, and the battery cell is positioned in the shell; one side edge of the shell is an integrally-formed sealing edge, the shell is provided with a heat sealing area, the heat sealing area is arranged around the battery cell, the sealing edge is provided with an air entraining notch, and the side wall of the air entraining notch is located in the heat sealing area. When gas in the shell is expanded, the part, corresponding to the air entraining notch, of the heat sealing area can bear less pressure than the rest part of the heat sealing area, so that the air entraining notch is easier to open due to expansion, and the gas can be discharged through the opened air entraining notch in the gas production expansion process of the battery; meanwhile, due to the fact that the air entraining notch is formed in the integrally-formed sealing edge, the portion outside the air entraining notch cannot be opened immediately, air is effectively prevented from being exhausted from other portions, and the effect of directional exhaust is achieved.

Description

Technical Field

[0001] The utility model relates to the technical field of batteries, in particular to a single battery, a battery, electrical equipment and a battery processing device. Background Art

[0002] The common structure of current soft-pack batteries is to place the battery cell inside a shell, which is usually made of aluminum-plastic film, which is pressed and heat-sealed to form an edge seal. During the use of soft-pack batteries, abnormal conditions such as short circuits may occur, causing the temperature inside the battery to rise rapidly. The decomposition of the positive and negative electrode materials and electrolyte produces a large amount of gas and releases a large amount of heat, causing the shell to expand and bulge. When the pressure is too high, it is easy to cause thermal runaway. At this time, the aluminum-plastic film edge seal will rupture, and gas will be ejected from the rupture. However, the rupture location is random, which means that the direction of the explosion is uncertain during thermal runaway. Utility Model Content

[0003] The utility model provides a single cell, a battery, electrical equipment and a battery processing device, so as to discharge the gas generated inside the battery in a directionally controlled manner.

[0004] In order to achieve the above-mentioned purpose, the present invention provides the following technical solutions:

[0005] According to a first aspect of the present invention, a single cell battery is provided, comprising a shell and a battery cell, wherein the battery cell is located within the shell; one side of the shell is an integrally formed sealing edge, the shell has a heat-sealing area, the heat-sealing area is arranged around the battery cell, the sealing edge is provided with an air-inlet notch, and the side wall of the air-inlet notch is located within the heat-sealing area.

[0006] The single cell battery provided by the present invention has an air inlet notch provided on the sealing edge, and the side wall of the air inlet notch is located within the heat-sealed area, thereby ensuring that the side wall of the air inlet notch is also in a sealed state during normal use. When the gas inside the shell expands, the pressure that the portion of the heat-sealed area corresponding to the air inlet notch can withstand is less than the pressure that the rest of the heat-sealed area can withstand, and the air inlet notch is more likely to rupture or open due to expansion. During the battery gas production and expansion process, the gas can be discharged through the opened air inlet notch, thereby playing a gas drainage role. At the same time, since the air inlet notch is provided on the integrally formed sealing edge, the portion outside the air inlet notch will not immediately rupture or open, thereby effectively preventing the gas from being discharged from other portions, thereby guiding the gas to flow to the air inlet notch and discharge to the outside of the shell, thereby playing a directional exhaust role.

[0007] According to a second aspect of the present invention, a battery is provided, comprising the single cell provided by the present invention.

[0008] The battery provided by the utility model can discharge the gas generated inside the battery in a directionally manner from the air inlet notch due to the use of the single battery provided by the utility model.

[0009] According to a third aspect of the present invention, an electrical device is provided, comprising the battery provided by the present invention.

[0010] The electric device provided by the utility model uses the battery provided by the utility model. When the battery experiences thermal runaway, gas generated inside the battery is directionally discharged from the air inlet notch, thereby improving the safety of the electric device.

[0011] According to a fourth aspect of the present invention, a battery processing device is provided for processing the single battery provided by the present invention, the battery processing device comprising a first heat sealing head and a second heat sealing head, the first heat sealing head being provided with a raised portion, and the second heat sealing head being provided with a recessed portion; and / or the first heat sealing head being provided with a recessed portion, and the second heat sealing head being provided with a raised portion; the first heat sealing head and the second heat sealing head being provided with a raised portion; the first heat sealing head and the second heat sealing head being respectively located on either side of the folded first sub-shell and the second sub-shell, the raised portion cooperating with the recessed portion to heat-seal the first heat-sealing portion of the first sub-shell and the second heat-sealing portion of the second sub-shell to form the heat-sealing area, and the sealing edge being cut to form the air entrainment gap.

[0012] The battery processing device provided by the present utility model can heat-seal the first heat-sealing portion of the first subshell and the second heat-sealing portion of the second subshell to form a heat-sealing area by providing a first heat-sealing head and a second heat-sealing head, and through the cooperation of the raised portion and the recessed portion. At the same time, the sealing edge can also be cut to form an air entrainment gap. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] For a better understanding of the present application, reference may be made to the embodiments shown in the following drawings. The components in the drawings are not necessarily to scale, and related elements may be omitted in order to emphasize and clearly illustrate the technical features of the present application. In addition, related elements or components may have different arrangements as known in the art. In addition, in the drawings, the same reference numerals represent the same or similar components in each figure. Among them:

[0014] Figure 1 A schematic structural diagram of a single cell provided in this embodiment;

[0015] Figure 2 for Figure 1 A partial enlarged view of point A in the middle;

[0016] Figure 3 A schematic diagram of a single battery provided in this embodiment in a venting state;

[0017] Figure 4 A schematic structural diagram of the shell of the single cell provided in this embodiment before heat sealing;

[0018] Figure 5 This is a schematic structural diagram of the battery processing device provided in this embodiment.

[0019] The following are the descriptions of the reference numerals:

[0020] 10-shell; 11-first subshell; 111-first dent area; 12-second subshell; 121-second dent area; 13-sealing edge; 14-heat sealing area; 20-battery cell; 30-ear; 40-air inlet; 41-first side wall; 42-second side wall; 51-first heat sealing head; 511-raised portion; 52-second heat sealing head; 521-recessed portion. DETAILED DESCRIPTION

[0021] The following will be combined with the accompanying drawings in the example embodiments of the present application to clearly and completely describe the technical solutions in the example embodiments of the present application. The example embodiments described herein are for illustrative purposes only and are not intended to limit the scope of protection of the present application. Therefore, it should be understood that various modifications and changes can be made to the example embodiments without departing from the scope of protection of the present application.

[0022] In the description of this application, unless otherwise expressly specified or limited, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance; the term "plurality" refers to two or more; and the term "and / or" includes any and all combinations of one or more of the associated listed items. In particular, reference to "the / the" object or "an" object is also intended to mean one of a possible plurality of such objects.

[0023] Unless otherwise specified or explained, the terms "connect," "fixed," etc. should be understood broadly. For example, "connected" can mean a fixed connection, a detachable connection, an integral connection, an electrical connection, or a signal connection; "connected" can mean a direct connection or an indirect connection through an intermediary. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0024] Furthermore, in the description of the present application, it should be understood that the directional words such as “upper”, “lower”, “inner” and “outer” described in the example embodiments of the present application are described from the perspectives shown in the accompanying drawings and should not be understood as limiting the example embodiments of the present application. It should also be understood that, in the context, when it is mentioned that an element or feature is connected to another element (one or more) “upper”, “lower”, or “inner” or “outer”, it can not only be directly connected to the other (one or more) elements “upper”, “lower” or “inner” or “outer”, but can also be indirectly connected to the other (one or more) elements “upper”, “lower” or “inner” or “outer” through an intermediate element.

[0025] In a first aspect, this embodiment provides a single cell. Figure 1 A schematic structural diagram of a single cell provided in this embodiment; Figure 2 for Figure 1 A partial enlarged view of point A in the middle; Figure 3 A schematic diagram of a single battery provided in this embodiment in a venting state; Figure 4 This is a schematic diagram of the structure of the shell 10 of the single battery provided in this embodiment before heat sealing, see Figures 1 to 4 As shown, this embodiment provides a single battery, including a shell 10 and a battery cell 20, wherein the battery cell 20 is located in the shell 10; one side of the shell 10 is an integrally formed sealing edge 13, and the shell 10 has a heat sealing area 14, which is arranged around the battery cell 20, and the sealing edge 13 is provided with an air inlet notch 40, and the side wall of the air inlet notch 40 is located in the heat sealing area 14.

[0026] The single cell battery provided in this embodiment has an air inlet notch 40 provided on the sealing edge 13, and the sidewall of the air inlet notch 40 is located within the heat-sealed area 14, ensuring that the sidewall of the air inlet notch 40 is also in a sealed state during normal use. When the gas inside the shell 10 expands, the pressure that the portion of the heat-sealed area 14 corresponding to the air inlet notch 40 can withstand is less than the pressure that the rest of the heat-sealed area 14 can withstand, and the air inlet notch 40 is more likely to rupture or open due to expansion. During the battery gas production and expansion process, the gas can be discharged through the opened air inlet notch 40. At the same time, because the air inlet notch 40 is provided on the integrally formed sealing edge 13, the area outside the air inlet notch 40 will not immediately rupture or open, thereby effectively preventing gas from being discharged from other areas, thereby guiding the gas to flow to the air inlet notch 40 and discharge to the outside of the shell 10, thereby playing the role of drainage and directional exhaust.

[0027] For example, see Figure 3 As shown, the gas generated inside the housing 10 flows outward from the inside of the battery cell 20 in the direction of the arrow, converges to the position of the air inlet notch 40, and is discharged from the air inlet notch 40.

[0028] It should be understood that the air inlet 40 is an open gap, that is, the sealing edge 13 is disconnected at the location of the air inlet 40. This allows the gas inside the housing 10 to be discharged through the air inlet 40 when the air inlet 40 is opened. In other words, the air inlet 40 can function as a pressure relief valve. The gas on both sides of the air inlet 40, blocked by the sealing edge 13, will flow along the extension direction of the sealing edge 13 toward the location of the air inlet 40, thus guiding the flow and providing a directional valve opening.

[0029] Illustratively, the single cell provided in this embodiment is a soft-pack lithium battery.

[0030] In one embodiment, the housing 10 is made of aluminum-plastic film. The battery cell 20 is encapsulated therein through a punching and heat-sealing process, resulting in extremely high barrier properties, good heat-sealing performance, and corrosion resistance. The heat-sealing process is divided into side sealing, top sealing, and bottom sealing. For example, the bottom sealing process can simultaneously form an air inlet 40.

[0031] It should be noted that the punching process and the heat sealing process should be understandable to those skilled in the art, and are well known and easy to implement for those skilled in the art, so they will not be described in detail in this embodiment.

[0032] The soft-pack lithium battery's shell 10 is encapsulated with aluminum-plastic film, a thin film made from a composite of materials such as nylon (melting point 210-230°C), polyethylene terephthalate (PET) (melting point 250-255°C), aluminum (melting point 660°C), and polypropylene (PP) (melting point 165-170°C). The polypropylene film layer is located on the innermost side, utilizing its low melting point to seal the battery. The outer aluminum film layer has a higher melting point, which prevents the integrally molded sealing edge 13 from immediately cracking or opening.

[0033] In one embodiment, see Figure 4 As shown, the shell 10 includes a first sub-shell 11 and a second sub-shell 12. The first sub-shell 11 and the second sub-shell 12 are integrally formed. The first sub-shell 11 and the second sub-shell 12 are folded to form an accommodating cavity, and the battery cell 20 is located in the accommodating cavity; the first sub-shell 11 has a first heat-sealing portion, and the second sub-shell 12 has a second heat-sealing portion. The first heat-sealing portion and the second heat-sealing portion are fitted together to form a heat-sealing area 14, and the folded portion of the first sub-shell 11 and the second sub-shell 12 forms a sealing edge 13.

[0034] In a specific embodiment, both the first sub-shell 11 and the second sub-shell 12 are provided with a punching area, wherein the punching area provided in the first sub-shell 11 is named a first punching area 111 , and the punching area provided in the second sub-shell 12 is named a second punching area 121 .

[0035] For example, a first dent area 111 and a second dent area 121 are formed by punching on an aluminum-plastic film. The first dent area 111 and the second dent area 121 can be rectangular grooves of the same size. The first dent area 111 and the second dent area 121 are arranged in parallel and spaced apart. The portion between the first dent area 111 and the second dent area 121 can be a transition area, and the air inlet 40 is located in the transition area. The battery cell 20 is placed in the first dent area 111, and the aluminum-plastic film is folded, for example, along Figure 4 The dotted line in the figure is folded in half so that the second dent area 121 is opposite to the first dent area 111, thereby positioning the battery cell 20 in the accommodation cavity formed by the first dent area 111 and the second dent area 121. Specifically, along the thickness direction of the battery cell 20, a portion of the battery cell 20 is located in the first dent area 111, and the other portion is located in the second dent area 121.

[0036] The folded aluminum-plastic film is heat-sealed. Specifically, a first heat-sealing portion is located around the first punched area 111, and a second heat-sealing portion is located around the second punched area 121. After the aluminum-plastic film is folded, the first heat-sealing portion and the second heat-sealing portion are opposite each other. After heat sealing, the first heat-sealing portion and the second heat-sealing portion are affixed to each other to form a heat-sealed area 14. Simultaneously, the folded portion of the first subshell 11 and the second subshell 12 is heat-pressed to form a sealed edge 13.

[0037] Exemplarily, the first heat sealing portion and the second heat sealing portion are continuously arranged near the sealing edge 13, so as to ensure that after hot pressing, the sealing edge 13 and the heat sealing area 14 near the sealing edge 13 are in a completely sealed state without leaving any gaps.

[0038] During the heat-sealing process, the heat-sealed area 14 can be directly cut to form the air-entraining notch 40. Alternatively, a hole can be punched in the transition region. The hole can be symmetrical about the crease at the fold. After the aluminum-plastic film is folded, the notch can be formed at the location of the hole. For example, if the hole is circular, the aluminum-plastic film can be folded to form an arc-shaped air-entraining notch at the location of the circular hole. Alternatively, if the hole is diamond-shaped, the aluminum-plastic film can be folded to form a triangular air-entraining notch 40 at the location of the diamond-shaped hole.

[0039] It should be understood that the first heat-sealed portion and the second heat-sealed portion may refer to portions of the first sub-shell 11 and the second sub-shell 12 that are heat-sealed during heat sealing.

[0040] In other embodiments, the dent area may be provided only in the first sub-shell 11 , and all the battery cells 20 are located in the dent area of ​​the first sub-shell 11 . Alternatively, the dent area may be provided only in the second sub-shell 12 , and all the battery cells 20 are located in the dent area of ​​the second sub-shell 12 .

[0041] In one embodiment, see Figure 1 and Figure 2 As shown, the air inlet 40 is triangular in shape and has a first side wall 41 and a second side wall 42. The intersection of the first side wall 41 and the second side wall 42 is located between the battery cell 20 and the sealing edge 13. This ensures that the side walls of the air inlet 40 are also in a sealed state during normal use.

[0042] It should be understood that the intersection of the first side wall 41 and the second side wall 42 forms the vertex of the triangular air inlet gap.

[0043] In other embodiments, the shape of the air entrainment gap 40 may also be polygonal or arc-shaped, for example, rectangular, trapezoidal or other special shapes.

[0044] In this embodiment, the number of the air inlet notch 40 is one.

[0045] In other embodiments, the number of the air inlet holes 40 may be increased according to the gas production of the battery or the module time requirement.

[0046] In one embodiment, the battery cell further includes a tab 30 , which is located on a side of the housing 10 away from the sealing edge 13 .

[0047] In a specific embodiment, see Figure 1 As shown, there are two tabs 30 , which are led out from the side of the battery cell 20 away from the sealing edge 13 , and the polarities of the two tabs 30 are opposite. Specifically, one tab 30 has a positive polarity and the other tab 30 has a negative polarity.

[0048] The tab 30 can connect and conduct electricity. For example, the tab 30 includes a metal body and an insulating adhesive layer. The insulating adhesive layer can be made of polypropylene. During the heat sealing process between the aluminum-plastic film and the positive and negative electrodes, the insulating adhesive layer plays an insulating and sealing role.

[0049] For example, the battery cell 20 may be a laminated battery cell, comprising a first electrode sheet stacked on top of each other, a second electrode sheet having an electrical property opposite to that of the first electrode sheet, and a separator sheet disposed between the first and second electrode sheets, thereby forming a laminated battery cell by stacking multiple pairs of first and second electrode sheets. Of course, the battery cell 20 may also be a wound battery cell, i.e., the first electrode sheet, the second electrode sheet, and the separator disposed between the first and second electrode sheets are wound to form a wound battery cell.

[0050] It should be noted that the structures of the battery cell 20 and the tab 30 should be understandable to those skilled in the art, and are well known and easy to implement for those skilled in the art, so they will not be described in detail in this embodiment.

[0051] In a second aspect, this embodiment provides a battery, including the single cell provided by this embodiment.

[0052] The battery provided in this embodiment uses the single battery provided in this embodiment, so that the gas generated inside the battery can be discharged in a directionally manner from the air guide gap 40.

[0053] In one embodiment, the battery is a battery module, which includes multiple single cells. The battery module may also include end plates and side plates for securing the multiple single cells. A cushion may be provided between adjacent single cells, and a cushion may be provided between the end plates and the cells.

[0054] Since the battery structure is simple, it does not affect the grouping of battery modules and other operations, and the battery module can be vented or replenished, thereby increasing the service life of the battery module.

[0055] In another embodiment, the battery may also be a battery pack.

[0056] The battery pack also includes a battery box, in which the single cells are arranged. By arranging the single cells in the battery box, the battery box can protect the single cells.

[0057] It should be noted that when there are multiple single cells, the cells can be arranged along their stacking direction to form a battery pack, which can then be placed in the battery case. The cells can be secured by end plates and side plates. When the cells are placed directly in the battery case, there is no need to group the cells, and in this case, the end plates and side plates can be removed.

[0058] In a third aspect, this embodiment provides an electrical device, including the battery provided by this embodiment.

[0059] The electrical equipment provided in this embodiment uses the battery provided in this embodiment. When the battery experiences thermal runaway, the gas generated inside the battery is discharged directionally from the air inlet notch 40, thereby improving the safety of the electrical equipment.

[0060] For example, the electrical equipment can be a car, a ship or other power equipment, for example, an electric car. Of course, the electrical equipment can also be set to other types according to needs, and the details will not be repeated here.

[0061] In a fourth aspect, this embodiment provides a battery processing device for processing the single battery provided by this embodiment. Figure 5 For the structural diagram of the battery processing device provided in this embodiment, see Figure 5 As shown, the battery processing device includes a first heat sealing head 51 and a second heat sealing head 52, the first heat sealing head 51 is provided with a protrusion 511, and the second heat sealing head 52 is provided with a recessed portion 521; and / or, the first heat sealing head 51 is provided with a recessed portion 521, and the second heat sealing head 52 is provided with a protrusion 511; the first heat sealing head 51 and the second heat sealing head 52 are respectively located on both sides of the folded first sub-shell 11 and the second sub-shell 12, and the protrusion 511 cooperates with the recessed portion 521 to heat-seal the heat sealing area 14 and cut the sealing edge 13 to form an air inlet gap 40.

[0062] The battery processing device provided in this embodiment is capable of heat-sealing the first heat-sealing portion of the first sub-shell 11 and the second heat-sealing portion of the second sub-shell 12 by providing a first heat-sealing head 51 and a second heat-sealing head 52, and by cooperating with the protrusion 511 and the recessed portion 521, so as to form a heat-sealing area 14. At the same time as heat sealing, the sealing edge 13 can also be cut to form an air-inlet notch 40. That is, the air-inlet notch can be formed at one time with the heat-sealing area.

[0063] See also Figure 5 As shown, the first heat sealing head 51 is provided with a raised portion 511, and the second heat sealing head 52 is provided with a recessed portion 521. When in use, the battery cell 20 can be placed first. Figure 4 In the first punching area 111 shown, the aluminum-plastic film is then folded along the dotted line so that the battery cell 20 is accommodated in the accommodation cavity formed by the first punching area 111 and the second punching area 121, and then the folded transition area is placed between the first heat sealing head 51 and the second heat sealing head 52. The first heat sealing head 51 and the second heat sealing head 52 move toward each other so that the folded transition area is pressed and heat-sealed while the protrusion 511 and the recessed portion 521 cooperate. Part of the aluminum-plastic film is removed in the heat-sealed transition area to form an air inlet notch 40. The shape of the air inlet notch 40 is adapted to the shape of the recessed portion 521.

[0064] When there are multiple air ducting notches 40 , multiple protrusions 511 may be provided on the first heat sealing head 51 , and multiple recesses 521 may be provided on the second heat sealing head 52 , with the protrusions 511 corresponding to the recesses 521 one by one.

[0065] It should be understood that the battery processing device provided in this embodiment also includes heat sealing heads (not shown in the figure) for side sealing and top sealing, and lifting mechanisms for driving the movement of each heat sealing head, etc., which will not be repeated here.

[0066] In other embodiments, a recessed portion 521 may be provided on the first heat sealing head 51, and a raised portion 511 may be provided on the second heat sealing head 52. When there are multiple air entrainment notches 40, multiple recessed portions 521 may be provided on the first heat sealing head 51, and multiple raised portions 511 may be provided on the second heat sealing head 52, with the raised portions 511 corresponding one to one with the recessed portions 521.

[0067] Of course, when there are multiple air entrainment notches 40 , the first heat sealing head 51 may be provided with both a raised portion 511 and a recessed portion 521 , and the second heat sealing head 52 may be provided with both a recessed portion 521 and a raised portion 511 .

[0068] Those skilled in the art will readily conceive of other embodiments of the present invention after considering the specification and practicing the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the present invention that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein. The description and example embodiments are to be considered merely as exemplary, and the true scope and spirit of this application are indicated by the appended claims.

[0069] It should be understood that the present application is not limited to the precise structure described above and shown in the drawings, and various modifications and changes can be made without departing from the scope thereof. The scope of protection of the present application is limited only by the appended claims.

Claims

1. A single battery, characterized in that: The battery cell comprises a housing and a battery cell, wherein the battery cell is located in the housing; one side of the housing is an integrally formed sealing edge, the housing has a heat-sealing area, the heat-sealing area is arranged around the battery cell, the sealing edge is provided with an air-inlet notch, and the sidewall of the air-inlet notch is located within the heat-sealing area; The shell includes a first sub-shell and a second sub-shell, the first sub-shell and the second sub-shell are integrally formed, the first sub-shell and the second sub-shell are folded to form a accommodating cavity, and the battery cell is located in the accommodating cavity; the first sub-shell has a first heat-sealing portion, and the second sub-shell has a second heat-sealing portion, the first heat-sealing portion and the second heat-sealing portion are affixed to form the heat-sealing area, and the folded portion of the first sub-shell and the second sub-shell forms the sealing edge.

2. The single cell according to claim 1, characterized in that: The first subshell is provided with a dent area, and the first heat seal portion is located around the dent area; and / or the second subshell is provided with a dent area, and the second heat seal portion is located around the dent area; at least part of the battery cell is located in the dent area.

3. The single cell according to claim 1, characterized in that: The shape of the air entrainment gap is triangular, polygonal or arc-shaped.

4. The single cell according to claim 1, characterized in that: The air inlet notch is in a triangular shape and has a first side wall and a second side wall. The intersection of the first side wall and the second side wall is located between the battery core and the sealing edge.

5. The single cell according to any one of claims 1 to 4, characterized in that: The shell is made of aluminum-plastic film.

6. The single cell according to any one of claims 1 to 4, characterized in that: The housing further comprises a tab located on a side of the housing away from the sealing edge.

7. A battery, characterized in that: A single cell battery comprising the single cell battery according to any one of claims 1 to 6.

8. An electrical device, characterized in that: A battery comprising the battery of claim 7.

9. A battery processing device for processing the single battery according to any one of claims 1 to 6, characterized in that: The battery processing device includes a first heat sealing head and a second heat sealing head, wherein the first heat sealing head is provided with a convex portion and the second heat sealing head is provided with a concave portion; and / or, the first heat sealing head is provided with a concave portion and the second heat sealing head is provided with a convex portion; The first heat sealing head and the second heat sealing head are respectively located on both sides of the folded first sub-shell and the second sub-shell, and the raised portion cooperates with the recessed portion to heat-seal the first heat-sealed portion of the first sub-shell and the second heat-sealed portion of the second sub-shell to form the heat-sealed area, and the sealed edge is cut to form the air entrainment gap.

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