Soft package battery and preparation method thereof

Abstract

The embodiment of the invention relates to the technical field of electrochemical devices, and particularly discloses a soft package battery and a preparation method thereof, and the soft package battery comprises a battery cell and a packaging bag. The battery cell comprises an electrode assembly and a tab. The packaging bag is provided with a battery cell cavity, the electrode assembly is accommodated in the battery cell cavity, the tab extends out of the battery cell cavity from the electrode assembly, the edge of the packaging bag is configured to be a folding edge, a first sealing edge, a second sealing edge and a third sealing edge which are sequentially connected, the third sealing edge and the folding edge are adjacently arranged, and the first sealing edge and the third sealing edge are oppositely arranged; the tab at least partially extends out of the first sealing edge, and the second sealing edge is opposite to the folding edge. A seal is arranged on the packaging bag on one side, deviating from the battery cell cavity, of the third sealing edge, extends to the edge of the third sealing edge in the direction deviating from the tab and extending out of the battery cell cavity, and seals are arranged on the packaging bags on one sides, deviating from the battery cell cavity, of the first sealing edge and the second sealing edge. Through the structure, the compactness of the structure, the energy density of the soft package battery and the production efficiency are improved.

Description

Technical Field

[0001] The embodiments of the present application relate to the technical field of electrochemical devices, and particularly to a soft-pack battery and a preparation method thereof. Background Art

[0002] With the increasing demand for high-energy-density and high-safety batteries in the new energy industry, soft-pack batteries have become an important research direction in volume-sensitive fields such as wearable devices, micro electric vehicles, medical implant devices, portable electric tools, smart devices, and robots due to their characteristics such as flexible packaging, light weight, and uniform heat dissipation.

[0003] In the above-mentioned electronic devices, soft-pack batteries have become the core power supply solution due to their high energy density, thinness, and shape adaptability. However, limited by the extreme space constraints inside, the battery needs to reduce the redundant packaging size to improve the volume utilization rate. Therefore, the design optimization of the soft-pack battery structure urgently needs to be improved. Summary of the Invention

[0004] The inventors have found through research that in the above-mentioned volume-sensitive fields such as wearable devices, micro electric vehicles, medical implant devices, portable electric tools, smart devices, and robots, the size of the soft-pack battery needs to adapt to the product structure. Therefore, when the soft-pack battery is applied to these fields, at least part of the size of the soft-pack battery needs to be reduced. Currently, when manufacturing a soft-pack battery with a smaller size, it is necessary to punch a pit in a packaging bag with a larger size to form a battery cell cavity, place the battery cell in the battery cell cavity, and perform packaging, as well as injection and formation processes, and finally perform pre-cutting treatment and fine-cutting treatment to obtain a soft-pack battery with a smaller size. The inventors have found in the actual production process that multiple cuts on the edges of multiple packaging bags will have a greater impact on the size control of the soft-pack battery.

[0005] Based on this, the purpose of the present application is to provide a soft-pack battery and a preparation method thereof, aiming to improve the current situation of the soft-pack battery structure design and reduce the influence of the process requirements of multiple cuts on multiple edges of the packaging bag on the size control of the soft-pack battery.

[0006] According to the first aspect of the present application, to solve the above technical problems, a technical solution adopted by the present application is: to provide a soft-pack battery, which includes a battery cell and a packaging bag. The battery cell includes an electrode assembly and an electrode tab. The packaging bag is provided with a battery cell cavity, the electrode assembly is received in the battery cell cavity, the electrode tab extends out of the battery cell cavity from the electrode assembly, and the edge of the packaging bag is configured as a folding edge, a first sealing edge, a second sealing edge, and a third sealing edge that are sequentially connected. The third sealing edge and the folding edge are adjacent to each other, the third sealing edge is opposite to the first sealing edge, the electrode tab extends at least partially out of the first sealing edge, and the second sealing edge is opposite to the folding edge. There is a seal on the packaging bag on the side of the third sealing edge facing away from the battery cell cavity, and the seal extends from the direction in which the electrode tab extends out of the battery cell cavity to the edge of the third sealing edge. There are seals on the packaging bag on the sides of the first sealing edge and the second sealing edge facing away from the battery cell cavity.

[0007] In the above technical solution, during the formation of the packaging bag, one of the edges is folded to form a folding edge, and the first sealing edge, the second sealing edge, and the third sealing edge are sealed so that the three together with the folding edge enclose the battery cell cavity. The third sealing edge is a sealing edge with a seal, and the seal extends to the edge of the third sealing edge in a direction away from the extending direction of the electrode tab. The third sealing edge and the folding edge are adjacent to each other. On the one hand, the third sealing edge having a seal reduces the size of the soft-pack battery in the direction where the third sealing edge is provided, facilitates the structural design of the soft-pack battery, and improves the overall structural compactness; on the other hand, the third sealing edge and the folding edge being adjacent to each other can reduce the angular redundant structure, can improve the structural strength, sealing effect, and thermal management of the soft-pack battery, and reduce material waste.

[0008] In some preferred embodiments, the length of the battery cell is less than or equal to 15 mm. The soft-pack battery can reduce the size of the battery cell to adapt to and be installed in equipment with a small battery compartment space, thereby preferably improving the installation flexibility of the soft-pack battery.

[0009] In some preferred embodiments, the first sealing edge, the second sealing edge, and the third sealing edge satisfy at least one of the following conditions: a) In the direction in which the electrode tab extends out of the battery cell cavity, the first sealing edge is folded towards the cavity direction of the battery cell cavity. b) Around the direction in which the electrode tab extends out of the battery cell cavity, the second sealing edge is folded towards the cavity direction of the battery cell cavity. c) In the direction in which the electrode tab extends out of the battery cell cavity, the third sealing edge is folded towards the cavity direction of the battery cell cavity. That is, the edges of the first sealing edge and / or the second sealing edge and / or the third sealing edge are folding edge structures. On the one hand, a multi-layer sealing structure is formed to reduce the leakage of the electrolyte in the battery cell cavity and the intrusion of external contaminants; on the other hand, the space utilization rate can be effectively improved, and the energy density of the soft-pack battery can be increased; on the other hand, the thermal stress and mechanical stress can be dispersed, and the risk of the packaging bag cracking can be reduced.

[0010] In some preferred embodiments, the packaging bag includes a polymer adhesive layer, and the seal of the third seal edge is formed by bonding with the polymer adhesive layer. That is, the third seal edge connects the two sides of the folded packaging bag through the polymer adhesive layer, thereby forming the third seal edge after encapsulation, reducing the unbonded area of the third seal edge, improving the sealing effect of the third seal edge, and reducing the size of the third seal edge.

[0011] In some preferred embodiments, the packaging bag is provided with at least one first pit. The first pit and the other areas outside the first pit together enclose an electrode core cavity for receiving the electrode assembly. Since the space sizes in different installation environments are different and the size requirements of the soft-pack battery in the thickness direction are different, the thickness of the electrode core cavity can be adjusted by the thickness of the first pit, improving the flexibility of production and manufacturing and effectively improving the production efficiency.

[0012] In some preferred embodiments, in the direction in which the tab extends relative to the electrode core cavity, the width d of the third seal edge satisfies 0.9 mm ≤ d ≤ 15 mm. More preferably, the width d of the third seal edge satisfies 1 mm ≤ d ≤ 2 mm. When the width of the third seal edge is less than 0.9 mm, the encapsulation strength cannot be satisfied. That is, when the width d of the third seal edge is greater than or equal to 0.9 mm, the minimum encapsulation strength of the third seal edge can be satisfied, enabling the seal edge to pass the drop performance test; when the width of the third seal edge is between 1 mm and 2 mm, the improvement in encapsulation strength is relatively large; when the width of the third seal edge reaches 2 mm, the improvement in encapsulation strength obtained by continuing to increase the width of the third seal edge is relatively small, and considering the influence of the size on the energy density benefit of the soft-pack battery, therefore, when the width d of the third seal edge satisfies 1 mm ≤ d ≤ 2 mm, a technical solution that satisfies the encapsulation strength and has a relatively high energy density benefit can be obtained; when the width of the third seal edge is greater than 15 mm, since the encapsulation strength is already satisfied when the width of the third seal edge is 15 mm, further increasing the encapsulation width is likely to lead to an increase in the cost of the soft-pack battery, material waste, and loss of energy density; that is, the third seal edge configured with a width satisfying 0.9 mm to 15 mm, and further preferably configured with a width satisfying 1 mm to 2 mm, can further improve the encapsulation strength of the packaging bag on the premise of satisfying the sealing performance, and obtain a better energy density of the soft-pack battery, reducing the risk of the packaging bag cracking.

[0013] According to the second aspect of the present application, the present application further provides a method for manufacturing the above-mentioned pouch cell. The manufacturing method includes: providing at least two battery cells, each battery cell including an electrode assembly and two tabs connected to the electrode assembly. Providing a packaging film, folding the packaging film in half along the width direction of the packaging film, and encapsulating the periphery of the folded packaging film to form a bag body. There is a cavity inside the bag body. Inside the cavity, the packaging film is further provided with at least two battery cell cavities with liquid inlets. The part of the cavity other than the battery cell cavities forms a liquid injection cavity. The battery cell cavities communicate with the liquid injection cavity through the liquid inlets.

[0014] In the above technical solution, two battery cells can be placed in the same packaging film, thereby improving production efficiency; in addition, the two battery cell cavities formed by the packaging film communicate with the same liquid injection cavity. That is, when injecting liquid into the liquid injection cavity, the two battery cell cavities can be injected with liquid simultaneously, further simplifying the production process, optimizing the production line structure, and improving production efficiency; and in some embodiments, it is necessary to connect two pouch cells for use. Therefore, the two interconnected pouch cells manufactured by the above manufacturing method can effectively reduce the waste of materials used for connecting the two pouch cells.

[0015] In some preferred embodiments, the step of providing the packaging film further includes: the setting directions of the two first pits are perpendicular to the folding direction of the packaging film. Punching at least two first pits in the packaging film, one first pit is located in the first area, and the other first pit is located in the second area. The setting directions of the first area and the second area are perpendicular to the folding direction of the packaging film. Placing a battery cell into one of the first pits. That is, the above method can improve the setting flexibility of the first pits on the packaging film, thereby reducing the process production difficulty, and evenly distributing the stress of the overall structure, facilitating the thin and light design, and adapting to different installation environments of pouch cells.

[0016] The steps of folding the packaging film in half further include: along the geometric center line of the packaging film in the width direction of the packaging film, folding the packaging film in half. Sealing the part of the bag body between two adjacent first pits to separate the two adjacent first pits. An injection port is opened on the bag body, and the injection port communicates with the injection cavity. Electrolyte is injected into all the battery cell cavities through the injection port. After the electrolyte is liquefied, the bag body is sealed at the liquid inlet to seal the battery cell cavities. Along the periphery of each battery cell cavity, the bag body is divided to obtain at least two soft-pack batteries, and the part of the bag body for packaging the battery cells forms the packaging bag of the soft-pack battery. That is, before folding the packaging film in half, at least two first pits need to be punched out on the packaging film, and the two first pits are arranged perpendicular to the folding direction of the packaging film to facilitate the formation of two staggered battery cell cavities. In addition, it is also necessary to seal the part between the two first pits of the same bag body to separate the two first pits. That is, the sealing here does not need to completely separate the bag body, but only needs to separate the two first pits, so as to realize that the two battery cell cavities communicate with the same injection cavity, and the electrolyte can be injected into the two battery cell cavities through the same injection port to improve production efficiency.

[0017] In some preferred embodiments, for the step of punching at least two first pits on the packaging film, it further includes: punching at least one second pit on the packaging film, and the second pit and one of the first pits are jointly arranged in the first area or the second area.

[0018] For the step of folding the packaging film in half, it further includes: after the packaging film is folded in half, the first pit and the second pit in the first area are butted and jointly form a battery cell cavity; or, the first pit and the second pit in the second area are butted and jointly form a battery cell cavity. By setting the second pit, on the one hand, a battery cell cavity formed by the butt joint of the first pit and the second pit, and another battery cell cavity surrounded by the first pit and other areas of the packaging film, thus improving the flexibility of the size design of the battery cell cavity, so that the first pit and the second pit can be configured as pits with different depths, so that the prepared soft-pack battery can adapt to different installation environments and achieve better structural strength.

[0019] In some preferred embodiments, the packaging film is folded in half to form a folding edge. The portion between the first pit in the first region and the first pit in the second region forms a pre-sealing edge. Since it is necessary to separate the two first pits before forming the liquid injection cavity, the pre-sealing edge needs to be formed first to reduce the mutual flow of the electrolyte in the two first pits and reduce the uneven distribution of the electrolyte. Along the periphery of each battery cell cavity, the step of dividing the bag further includes: in the direction of the folding of the packaging film, encapsulating the two side edges of the bag to form two first unsealed edges, and encapsulating the pre-sealing edge. Inject the electrolyte into all the battery cell cavities through the liquid injection port. Parallel to the folding edge, encapsulate the edge of the battery cell cavity relative to the folding edge. Divide the liquid injection cavity and the battery cell cavity. By setting the pre-sealing edge, the two battery cell cavities are separated, so that it is convenient to inject the electrolyte into the two battery cell cavities at the same time, and the two unsealed edges are encapsulated at the same time, further closing the bag to facilitate the formation of the liquid injection cavity, that is, in the same encapsulation process, the bag for liquid injection is encapsulated and the two battery cell cavities are separated, improving the production efficiency.

[0020] In some preferred embodiments, the step of dividing the bag further includes: dividing the bag along the pre-sealing edge to obtain at least two soft-pack batteries. That is, the two sides of the pre-sealing edge are battery cell cavities. Combining with the cutting step in the above steps, after the pre-sealing edge is cut, the third sealing edges of the above soft-pack batteries are respectively formed. Therefore, the third sealing edge does not need to cut the non-fitted area of the packaging film again, simplifying the preparation process of the soft-pack battery and improving the production efficiency.

[0021] In some preferred embodiments, for providing the packaging film, the step of punching at least two first pits in the packaging film further includes: the packaging film has a first folding portion and a second folding portion. At least two first pits are punched in at least one of the first folding portion and the second folding portion. And one of the first pits is located in the first region and the other first pit is located in the second region. The step of folding the packaging film in half and encapsulating the edge of the folded packaging film to form a bag with a cavity inside further includes: stacking the first folding portion and the second folding portion, and encapsulating the peripheries of the first folding portion and the second folding portion. That is, the first folding portion and the second folding portion of the packaging film are formed into a wrapped bag through folding. Therefore, the first pit can be formed in at least one of the first folding portion and the second folding portion in the first region or the second region to form the battery cell cavity. This step increases the operable area for punching the first pit in the packaging film, reduces the process requirements, and improves the production efficiency. In addition, after the first folding portion and the second folding portion are stacked, the first folding portion and the second folding portion completely overlap, which is convenient for forming the bag and subsequent encapsulation and cutting processes.

[0022] In some preferred embodiments, the step of dividing the pouch body along the periphery of each battery cell cavity to obtain at least two soft-pack batteries further includes: the soft-pack batteries satisfy one of the following conditions: a) For two soft-pack batteries divided from the same pouch body, at least one of the soft-pack batteries has the anode tab close to the folding edge and the cathode tab away from the folding edge. b) For two soft-pack batteries divided from the same pouch body, the anode tabs of the two soft-pack batteries are away from the folding edge and the cathode tabs are close to the folding edge. First, after the first folding portion and the second folding portion are stacked, the first part of the second folding portion and a part of the first folding portion are used to form two battery cell cavities, and the second part and another part of the first folding portion are used to form a liquid injection cavity, so that two soft-pack batteries can be obtained by dividing the same packaging film, thereby improving production efficiency. Second, the soft-pack batteries that satisfy one of the above conditions can optimize the position of the tabs and the structure of the soft-pack batteries.

[0023] In some preferred embodiments, for the packaging film: the second folding portion includes a first part and a second part, and the first part is connected to the first folding portion. The first pit provided in the second folding portion is located in the first part. The first pit provided in the first folding portion is located on the part of the first folding portion that is used to overlap with the first part. The second part and the first folding portion enclose a liquid injection cavity, and the liquid injection cavity is used to inject electrolyte into the first pit. Through the above structure, when the first part and the second part are injecting liquid, the liquid injection cavity formed by the second part can inject liquid into the battery cell cavity in the first part, and is convenient for encapsulation and cutting after the liquid injection is completed, thereby improving production efficiency.

[0024] In some preferred embodiments, the first folding portion, the first part, and the second part are arranged in sequence along the length direction of the packaging film; and / or, at least two first pits are arranged in sequence along the width direction of the packaging film. Thus, the packaging films of the two soft-pack batteries are folded in the same direction, which is convenient for encapsulation and division.

[0025] In some preferred embodiments, the area of the first folding portion is equal to the area of the second folding portion. So that after the first folding portion is folded relative to the second folding portion, the edges overlap, which is convenient for encapsulation and cutting, and can effectively improve the structural stability of the soft-pack battery.

[0026] In some preferred embodiments, for the packaging film: along the width direction of the packaging film, the sum of the lengths of the two first pits is less than the width of the packaging film. The width of the packaging film is greater than or equal to 15 mm. That is, for the soft-pack battery prepared from this packaging film, the size in the direction where the tabs extend relative to the battery cell cavity is small, which can improve the energy density and installation flexibility of the soft-pack battery.

[0027] In some preferred embodiments, the number of the first pits is the same as that of the second pits, and the first pits and the second pits are docked one by one. By setting the same number of the first pits and the second pits and docking them with each other, it is convenient to manufacture the soft-pack batteries of the same specification.

[0028] Additional aspects and advantages of the embodiments of the present application will be described, shown, or elucidated in part in the subsequent description, or via the implementation of the embodiments of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] One or more embodiments are exemplarily illustrated by corresponding drawings. These exemplary illustrations do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings are represented as similar elements, unless otherwise stated, and the dimensions in the drawings do not constitute a proportional limitation.

[0030] Figure 1 is the first schematic diagram of the soft-pack battery provided by one embodiment of the present application;

[0031] Figure 2 is the second schematic diagram of the soft-pack battery provided by one embodiment of the present application;

[0032] Figure 3 is the third schematic diagram of the soft-pack battery provided by one embodiment of the present application;

[0033] Figure 4 is the fourth schematic diagram of the soft-pack battery provided by one embodiment of the present application;

[0034] Figure 5 is the fifth schematic diagram of the soft-pack battery provided by one embodiment of the present application;

[0035] Figure 6 is the sixth schematic diagram of the soft-pack battery provided by one embodiment of the present application;

[0036] Figure 7 is the first unfolded schematic diagram of the soft-pack battery provided by one embodiment of the present application;

[0037] Figure 8 is the first flowchart of the method for manufacturing a soft-pack battery provided by one embodiment of the present application;

[0038] Figure 9 is the second flowchart of the method for manufacturing a soft-pack battery provided by one embodiment of the present application;

[0039] Figure 10 is the third flowchart of the method for manufacturing a soft-pack battery provided by one embodiment of the present application;

[0040] Figure 11It is the second unfolded schematic diagram of the pouch cell provided by one embodiment of the present application;

[0041] Figure 12 It is the third unfolded schematic diagram of the pouch cell provided by one embodiment of the present application;

[0042] Figure 13 It is the fourth unfolded schematic diagram of the pouch cell provided by one embodiment of the present application;

[0043] Figure 14 It is the fifth unfolded schematic diagram of the pouch cell provided by one embodiment of the present application;

[0044] Figure 15 It is the fourth flowchart of the manufacturing method of the pouch cell provided by one embodiment of the present application;

[0045] Figure 16 It is the fifth flowchart of the manufacturing method of the pouch cell provided by one embodiment of the present application;

[0046] Figure 17 It is the sixth flowchart of the manufacturing method of the pouch cell provided by one embodiment of the present application;

[0047] Figure 18 It is the seventh flowchart of the manufacturing method of the pouch cell provided by one embodiment of the present application;

[0048] Figure 19 It is the eighth flowchart of the manufacturing method of the pouch cell provided by one embodiment of the present application;

[0049] Figure 20 It is the first schematic diagram of the manufacturing method of the pouch cell provided by one embodiment of the present application;

[0050] Figure 21 It is the second schematic diagram of the manufacturing method of the pouch cell provided by one embodiment of the present application;

[0051] Figure 22 It is the third schematic diagram of the manufacturing method of the pouch cell provided by one embodiment of the present application.

[0052] The reference numerals are as follows:

[0053]

[0054] Detailed Description of the Invention

[0055] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the following will clearly describe the technical solutions in the embodiments of this application with reference to the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are some, but not all, of the embodiments of this application.

[0056] Reference to "embodiment" in this application means that a specific feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of this application. The phrase appears in various places in the specification and does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments.

[0057] In the description of the embodiments of this application, technical terms such as "first" and "second" are only used to distinguish different objects and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity, specific order, or primary-secondary relationship of the indicated technical features. In the description of the embodiments of this application, "a plurality of" means two or more, unless otherwise specifically defined.

[0058] In the description of the embodiments of this application, the term "and / or" is merely a description of the association relationship between associated objects, indicating that three relationships may exist. For example, A and / or B may represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this article generally represents an "or" relationship between the associated objects before and after.

[0059] The term "vertical" is used to describe the ideal state between two components. In the actual production or use state, there may be a state approximately vertical between two components. For example, in combination with numerical description, vertical may refer to the included angle range between two straight lines being between 90 ± 10°, vertical may also refer to the dihedral angle range between two planes being between 90 ± 10°, and vertical may also refer to the included angle range between a straight line and a plane being between 90 ± 10°. The two components described as "vertical" may not be absolute straight lines or planes, and may also be approximately straight lines or planes. From a macroscopic perspective, as long as the overall extension direction is a straight line or a plane, the components can be considered "straight lines" or "planes".

[0060] The technical features involved in different embodiments of this application described below can be combined with each other as long as they do not conflict with each other.

[0061] In a first aspect, please refer to Figure 1 , this application provides a soft-pack battery 1000, and the soft-pack battery 1000 includes a battery cell 100 and a packaging bag 200.

[0062] In some embodiments, the battery cell 100 includes an electrode assembly 101 and a tab 102.

[0063] In some embodiments, the packaging bag 200 is provided with a battery cell cavity 201, the electrode assembly 101 is accommodated in the battery cell cavity 201, and the tab 102 extends out of the battery cell cavity 201 from the electrode assembly 101. In the current soft-pack battery 1000, after the packaging bag 200 is formed, there are at least three sealed edges and one folded edge 202, and these sealed edges are away from the side of the battery cell cavity 201 and have a seal, and then a secondary cutting or folding process is required to make the soft-pack battery 1000 meet the size requirements. However, when the multiple sealed edges are subjected to secondary cutting or folding, it is easy to produce a large error in the size of the soft-pack battery 1000, and in more use environments, the side opposite to the tab 102 of the soft-pack battery 1000 requires higher size requirements. These methods have low production efficiency, large errors, insufficient structural strength, insufficient sealing effect, poor stress concentration and thermal stress concentration, and are easy to lead to low product quality rate.

[0064] In order to solve or at least partially solve the above technical problems, in the soft-pack battery 1000 provided in the present application, the edge of the packaging bag 200 is configured as a folding edge 202, a first sealing edge 203, a second sealing edge 204 and a third sealing edge 205 connected in sequence, the first sealing edge 203 and the folding edge 202 are arranged adjacent to each other, the first sealing edge 203 and the third sealing edge 205 are arranged opposite to each other, the tab 102 at least partially extends from the first sealing edge 203, and the second sealing edge 204 is arranged opposite to the folding edge 202. The packaging bag 200 on the side of the third sealing edge 205 away from the battery cell cavity 201 has a seal, and the seal extends away from the direction in which the tab extends out of the battery cell cavity 201 to the edge of the third sealing edge 205, the first sealing edge 203 and the second sealing edge 204, and the packaging bag 200 on the side away from 201 has a seal.

[0065] Among them, "the seal deviates from the tab and extends to the edge of the third seal 205 in the direction extending out of the battery cell cavity 201, and there is a seal on the packaging bag 200 on the side of the first seal 203 and the second seal 204 that deviates from 201." It means that after the soft-pack battery 1000 is prepared, the third seal 205 is a sealed edge formed after encapsulation to form a seal structure, and the seal of the third seal 205 deviates from the tab and extends to the edge of the packaging bag 200 of the third seal 205 in the direction extending out of the battery cell cavity 1000. Furthermore, when the soft-pack battery is applied in many scenarios, no secondary cutting is required. Furthermore, there is no need to cut off the edge of the redundant packaging bag 200, and only the seal structure needs to be retained to meet the process requirements of small size and good sealing effect. The edge of the packaging bag 200 that requires secondary cutting is reduced, the rework rate is reduced, and the production efficiency and product yield are improved; and since no secondary cutting is required, there is no need to measure and cut the unbonded area at the edge of the packaging bag 200, reducing the error; and for the bonded edge of the packaging bag 200, a sealed edge can be formed without cutting, making the structure integrity of the soft-pack battery 1000 relatively high, the structural strength relatively good, and the sealing effect relatively good, thereby significantly enhancing the sealing integrity of the encapsulation area of the soft-pack battery 1000, reducing the risk of moisture and oxygen penetration, and thus maintaining the stability of the electrolyte inside the battery cell 100; that is, the sealed edge of the packaging bag 200 can evenly distribute the encapsulation stress, reducing the risk of tab 102 offset or internal short circuit caused by local virtual sealing or delamination; at the same time, the melting uniformity of the inner layer of the packaging bag 200 made of aluminum-plastic film is improved, reducing the phenomenon of uneven encapsulation thickness caused by fluctuations in heat-sealing parameters.

[0066] In the above technical solution, during the process of forming the packaging bag 200, one of the edges is folded to form a folded edge 202, and the first seal 203, the second seal 204, and the third seal 205 are encapsulated so that the three together with the folded edge 202 enclose the battery cell cavity 201, where the third seal 205 is a sealed edge with a seal and is arranged adjacent to the folded edge 202. On the one hand, the third seal 205 having a seal reduces the size of the soft-pack battery 1000 in the direction where the third seal 205 is set, facilitating the structural design of the soft-pack battery 1000 and improving the compactness of the overall structure; on the other hand, the third seal 205 and the folded edge 202 are arranged adjacent to each other, which can reduce the angular redundant structure, improve the structural strength, sealing effect, and thermal management of the soft-pack battery, and reduce material waste.

[0067] In some embodiments, for the above-mentioned seal, the "seal" refers to the imprint obtained after encapsulation. The packaging bag 200 includes a polymer adhesive layer (not shown in the figure), and the seal of the third seal edge 205 is formed by bonding with the polymer adhesive layer. That is, the third seal edge 205 connects the two sides of the folded packaging bag 200 through the polymer adhesive layer, thereby forming the third seal edge 205 after encapsulation, reducing the unbonded area of the third seal edge 205, improving the sealing effect of the third seal edge 205, and reducing the size of the third seal edge 205. The materials of the polymer adhesive layer include but are not limited to polyurethane adhesive layer, polypropylene / CPP heat-sealing layer, modified polypropylene tab sealant, etc.

[0068] In some embodiments, the length of the battery cell 100 can also be less than or equal to 15 mm. Specifically, in the direction in which the tab 102 extends relative to the battery cell cavity 201, the length of the battery cell 100 is less than or equal to 15 mm, and the length of the battery cell 100 is relatively small, so that the soft-pack battery 1000 can be adapted to electronic products and electrical equipment with a relatively small battery compartment space, such as: true wireless earphones (True Wireless Stereo devices, abbreviated as TWS devices), smart watches, smart bracelets and other wearable earphones; or, medical implant devices such as wire-free cardiac pacemakers, implantable cardiac detectors, deep brain stimulators, cochlear implants, continuous glucose monitoring implants, etc.; and other micro electric vehicles, portable electric tools, smart devices and robot micro-joint devices, etc. In addition, reducing the size in the direction in which the tab 102 extends relative to the battery cell cavity 201 can reduce the difficulty of the internal circuit layout of the electronic equipment using the soft-pack battery 1000 and improve the internal space utilization rate of these electronic equipment.

[0069] In some embodiments, please refer to Figures 2 to 4 , and in combination with other drawings, the first seal edge 203, the second seal edge 204 and the third seal edge 205 of the soft-pack battery 1000 satisfy at least one of the following conditions: a) In the direction in which the tab 102 extends relative to the battery cell cavity 201, the first seal edge 203 is folded and arranged towards the cavity direction of the battery cell cavity 201. b) Around the direction in which the tab 102 extends relative to the battery cell cavity 201, the second seal edge 204 is folded and arranged towards the cavity direction of the battery cell cavity 201. c) In the direction in which the tab 102 extends relative to the battery cell cavity 201, the third seal edge 205 is folded and arranged towards the cavity direction of the battery cell cavity 201. Through the above structure, the edges of the first seal edge 203 and / or the second seal edge 204 and / or the third seal edge 205 are folded-edge structures in a folded shape. On the one hand, a multi-layer sealing structure is formed, reducing the leakage of the electrolyte in the battery cell cavity 201 and the intrusion of external pollutants. In addition, the first seal edge 203 and the second seal edge 204 of the soft-pack battery 1000 are folded towards the battery cell cavity 201, or the first seal edge 203 is folded towards the battery cell cavity 201, or the second seal edge 204 is folded towards the battery cell cavity 201. Among them, in combination with the attached Figure 5, the dashed area in the figure shows the position of the third sealing edge 205 before folding. By folding the third sealing edge 205, the size of the soft-pack battery 1000 is further reduced, the energy density is increased, and the installation flexibility of the soft-pack battery 1000 is improved. Among them, the improvement of the installation flexibility means that the soft-pack battery 1000 provided by the present application can be adapted to electronic devices with a variety of or smaller battery compartment spaces. In some embodiments, after the third sealing edge 205 is folded, at least one of the first sealing edge 203 and the second sealing edge 204 can be finely cut, so as to further reduce the influence of the folded third sealing edge 205 on the thickness of the soft-pack battery 1000, so as to facilitate the manufacture of an ultra-thin battery. It should still be noted that such an ultra-thin battery meets both the ultra-thin and ultra-short requirements at the same time. Compared with the current soft-pack battery 1000, the soft-pack battery 1000 provided by the present application reduces the number of edges to be folded, reduces the influence of the folded edge of the packaging bag 200 on the thickness of the soft-pack battery 1000, and can reduce the process difficulty of making the soft-pack battery 1000 into an ultra-thin battery. It should still be noted that such an ultra-thin battery meets both the ultra-thin and ultra-short requirements at the same time. Among them, the small frames at the edges of the first sealing edge 203 and the second sealing edge 204 in the figure represent the edges of the packaging bag 200 outside the seal.

[0070] In some other embodiments, please refer to Figure 6 , and in combination with other drawings, the dashed area in the figure shows the position of the third sealing edge 205 before folding. The folding state of the third sealing edge 205 can also be combined with the embodiments of the folding states of the above first sealing edge 203 and / or second sealing edge 204.

[0071] Combined with the above-mentioned specification appendix Figure 2 Figure 3 and Figure 5 , an exemplary description is given of the energy density gain brought by the above-mentioned edge folding structure to the soft-pack battery 1000:

[0072] It is assumed that the width of the soft-pack battery 1000 perpendicular to the extending direction of the tab 102 is W, the length of the soft-pack battery 1000 along the extending direction of the tab 102 is L, the width of the first sealing edge 203 is T, the width of the third sealing edge 205 is d, and the width of the second sealing edge 204 is s.

[0073] (1) Calculate for the Figure 2 embodiment in: (L - T - d) × (W - s) is the difference between the length of the soft-pack battery 1000 along the extending direction of the tab 102 and the sum of the widths of the first sealing edge 203 and the third sealing edge 205, and the difference between the width of the soft-pack battery 1000 perpendicular to the extending direction of the tab 102 and the second sealing edge 204. The product of the two differences is Figure 2 the main body area of the soft-pack battery 1000 in the embodiment shown.

[0074] (2) Calculate the embodiments in Figure 3 : (L - T - d) × [W - (s - 1.75)] is the difference between the length of the soft-pack battery 1000 along the extending direction of the tab 102 and the sum of the widths of the first sealing edge 203 and the third sealing edge 205, and the difference between the width of the soft-pack battery 1000 perpendicular to the extending direction of the tab 102 and the distance saved by the folded edge of the second sealing edge 204 minus 1.75 mm. The product of the two differences is Figure 3 the main body area of the soft-pack battery 1000 in the embodiment shown. To obtain that the main body area obtained by folding the second sealing edge 204 is larger than the main body area obtained by folding the first sealing edge 203.

[0075] (3) Calculate the embodiments in Figure 5 : [L - T - (d - 1.75)] × (W - s) is the first difference between the length of the soft-pack battery 1000 along the extending direction of the tab 102 and the width of the first sealing edge 203, the second difference between the width of the third sealing edge 205 and the distance saved by the folded edge minus 1.75 mm. The third difference between the two is calculated through the first difference and the second difference, and the fourth difference between the width of the soft-pack battery 1000 perpendicular to the extending direction of the tab 102 and the second sealing edge 204. Calculate the product of the third difference and the fourth difference, and this product is Figure 5 the main body area of the soft-pack battery 1000 in the embodiment shown. To obtain that the main body area of this embodiment is larger than the soft-pack battery 1000 in the embodiment shown in Figure 2 above. And since the width of the above third sealing edge 205d is between 0.8 mm and 15 mm, the length of the obtained soft-pack battery 1000 is smaller. Therefore, the above embodiments provided can provide a technical solution with higher energy density.

[0076] In some embodiments, please refer to Figure 7For understanding, in combination with the foregoing drawings, the packaging bag 200 is provided with at least one first pit 206, the first pit 206 and other regions outside the first pit 206. Alternatively, in some other embodiments, the first pit 206 and another first pit 206 jointly enclose an electrode core cavity 201, and the electrode core cavity 201 is used to accommodate the electrode assembly 101. It can be understood that when a part of the packaging bag 200 is provided with the first pit 206 and forms the electrode core cavity 201 with other regions of the packaging bag 200, the thickness of the formed electrode core cavity 201 can be effectively reduced, so as to facilitate the manufacture of the ultra-thin electrode core 100; and, the punching die only needs to perform the punching process on a part of it, reducing the equipment cost and debugging difficulty, reducing the process steps, production cycle length and energy consumption; and, reducing the deformation of the surface of the packaging bag 200 where the punching is not performed, maintaining the structural strength of at least part of the packaging film 200, improving the sealing effect, reducing the material loss, and reducing the potential rupture risk of the packaging bag 200. When the first pit 206 and another first pit 206 of the packaging bag 200 jointly enclose the electrode core cavity 201, the load of the soft-pack battery 1000 can be effectively evenly distributed, reducing the rupture risk caused by unilateral stress concentration; the symmetrical structure can effectively improve the anti-bending ability of the soft-pack battery 1000; and the structure of the two first pits 206 can provide a larger installation and arrangement space for the tab 102, improving its installation flexibility; the symmetrical electrode core cavity 201 formed by the two first pits 206 can promote the two-way penetration of the electrolyte between the positive and negative electrode plates, reducing the wetting dead angle and improving the charge and discharge efficiency.

[0077] In some embodiments, in the direction in which the tab 102 extends relative to the battery cell cavity 201, the width d of the third seal 205 satisfies 0.9 mm ≤ d ≤ 15 mm. When the width of the third seal 205 is less than 0.9 mm, the encapsulation strength cannot be satisfied. That is, when the width d of the third seal 205 is greater than or equal to 0.9 mm, the minimum encapsulation strength of the third seal 205 can be satisfied, enabling the seal to pass the drop performance test; when the width of the third seal 205 is greater than 15 mm, since the encapsulation strength has been satisfied when the width of the third seal 205 is equal to 15 mm, further increasing the encapsulation width of the third seal 205 easily leads to an increase in the cost of the soft-pack battery 1000, material waste, and a loss of energy density. In some more preferred embodiments, the width d of the third seal 205 satisfies 1 mm ≤ d ≤ 2 mm. When the width of the third seal 205 is between 1 mm and 2 mm, the improvement in encapsulation strength is relatively large; when the width of the third seal 205 reaches 2 mm, the improvement in encapsulation strength brought about by further increasing the width of the third seal 205 is relatively small, and considering the impact of the size on the energy density benefit of the soft-pack battery 1000, therefore, when the width d of the third seal 205 satisfies 1 mm ≤ d ≤ 2 mm, a technical solution that satisfies the encapsulation strength and has a relatively high energy density benefit can be obtained. As for how to obtain the above technical solution, reference can be made to the test part in the following text. That is, the third seal 205 configured with a width satisfying 0.9 mm to 15 mm can further improve the encapsulation strength and reduce the risk of cracking of the packaging bag 200 on the premise of satisfying the sealing performance. And the third seal 205 configured with a width satisfying 1 mm to 2 mm can provide a third seal 205 that satisfies the encapsulation strength and has a relatively high energy density benefit. It can be understood that the width of the third seal 205 being greater than or equal to 0.9 mm helps to maintain the encapsulation strength, reduce the slow leakage of the electrolyte, and when the soft-pack battery 1000 thermally expands, reduce the influence of thermal stress and stress concentration at the edge on the third seal 205; the width of the third seal 205 being less than or equal to 15 mm is to improve the encapsulation strength to maintain the structural strength and sealing strength, and to reduce the cost brought by the process and the product, reduce material loss, and improve the energy conservation and environmental protection efficiency.

[0078] In a second aspect, please refer to Figure 7 and Figure 8 and in combination with other drawings. Based on the above soft-pack battery 1000, the present application further provides a preparation method for the soft-pack battery 1000 described above (hereinafter referred to as the preparation method). The preparation method includes:

[0079] S10: Provide at least two battery cells 100, each battery cell 100 including an electrode assembly 101 and two tabs 102 connected to the electrode assembly 101.

[0080] S20: Provide a packaging film 200'. Fold the packaging film 200' along the width direction of the packaging film 200, and seal the periphery of the folded packaging film 200' to form a bag body 207. There is a cavity 208 inside the bag body 207. Inside the cavity 208, the packaging film 200' is also provided with a battery cell cavity 201 with a liquid inlet 209. The part of the cavity 208 other than the battery cell cavity 201 forms a liquid injection cavity 210. The battery cell cavity 201 communicates with the liquid injection cavity 210 through the liquid inlet 209.

[0081] This preparation method aims to prepare a soft-pack battery 1000. Two battery cells can be placed in the same packaging film 200', that is, an electrode assembly can be placed in one battery cell cavity. This preparation method can perform the liquid injection process on two battery cell cavities 201 simultaneously, thereby improving production efficiency. Specifically, the packaging film 200' is folded along its width direction and the periphery of the folded packaging film 200' is sealed to form a bag body 207. Inside the bag body 207, there are a battery cell cavity 201 and a liquid injection cavity 210 connected through a liquid inlet 209. That is, the electrolyte in the liquid injection cavity 210 can enter the two battery cell cavities 201 simultaneously through the liquid inlet 209, thereby preparing two soft-pack batteries 1000 at the same time. On the one hand, the preparation efficiency of the above-mentioned soft-pack battery 1000 can be improved. On the other hand, the electrolyte components in the soft-pack batteries 1000 produced and prepared simultaneously can be made uniform, improving the product yield.

[0082] It should be added that the width direction of the packaging film 200' is perpendicular to the thickness direction. When observing along the thickness direction of the packaging film 200', in this application, the extension direction of the longer side of the size of the packaging film 200' is defined as the length direction, and the extension direction of the shorter side of the size of the packaging film 200' is defined as the width direction. Combining with the battery cell 100 for further understanding, the direction in which the tab 102 is connected to the electrode assembly 101 and extends relative to the electrode assembly 101 is the same as the width direction of the packaging film 200', and the direction perpendicular to the direction in which the tab 102 extends relative to the electrode assembly 101 is the same as the length direction of the packaging film 200'. It can be understood that in actual production, multiple packaging films 200' are placed in a roll shape on the equipment production line. The movement of the equipment production line drives the rolled packaging film 200' to unfold, and multiple packaging films 200' are connected in sequence along the length direction, so as to facilitate continuous movement along the equipment production line for subsequent processes after one cutting, without the need to adjust the placement direction of the packaging film 200'. In the following text, please also understand in combination with the drawings. In this application, the length direction of the packaging film 200' is also described through the first direction, the width direction of the packaging film 200' is described through the second direction, and the thickness direction of the packaging film 200' is described through the third direction.

[0083] In some other embodiments, the two connected pouch cells 1000 produced can be directly used. Currently, in some usage scenarios, it is necessary to connect two pouch cells 1000, such as in high-voltage environments like electric vehicles, electric tools, industrial equipment, and drones; and in environments where devices need to operate for a long time, such as portable medical devices, outdoor energy storage devices, and smart consumer electronic products. When the current pouch cells 1000 are applied to the above environments, two pouch cells 1000 need to be connected through another connecting material and placed in the battery compartment of the device; while the two pouch cells 1000 obtained by the preparation method provided in this application are directly connected to each other without the need to use an additional connecting material for fixing; on the one hand, the two pouch cells 1000 formed by the connected packaging film 200' have better structural strength; on the other hand, there is no need to use an additional connecting material for fixing, which reduces the material loss and the R & D and test costs of the additional connecting material; on the other hand, two connected pouch cells 1000 can be obtained without cutting or connecting, which simplifies the manufacturing process.

[0084] It should be noted that the "packaging film 200'" here and the "packaging bag 200" in the context are different shapes of the same packaging bag 200 in different production and manufacturing processes, and are collectively referred to as the packaging film 200' hereinafter. The packaging bag 200 used to form each pouch cell 1000 is at least part of the packaging film 200' here. That is, the packaging bags 200 of at least two pouch cells 1000 formed simultaneously together constitute the packaging film 200' here.

[0085] Please refer to Figure 9 , and in combination with other drawings, the steps of providing the packaging film 200' for S20 further include:

[0086] S201: The setting directions of the two first pits 206 are perpendicular to the folding direction of the packaging film 200'.

[0087] S202: Punch out at least two first pits 206 in the packaging film 200'. One first pit 206 is located in the first region, and the other first pit 206 is located in the second region. The setting directions of the first region and the second region are perpendicular to the folding direction of the packaging film 200'.

[0088] S203: Place a battery cell 100 into a first pit 206.

[0089] That is, the above method can improve the flexibility of setting the first pits 206 on the packaging film 200', thereby reducing the difficulty of process production, and making the force distribution of the overall structure uniform, facilitating the thin and light design, and adapting to the installation environments of different soft-pack batteries 1000. It should be noted that the setting directions of the two first pits 206 here are perpendicular to the folding direction of the packaging film 200', which is the setting direction after the packaging film 200' is folded in half, that is, the two first pits 206 can be located on the same side or opposite sides of the folded packaging film 200' at the same time. The two separated first pits 206 still respectively have liquid inlet ports 209 communicating with the liquid injection cavity 210. The liquid injection cavity 210 can be filled with liquid through the liquid injection port 2071, and the electrolyte can be injected into the battery cell cavity 201 through the liquid inlet ports 209 respectively.

[0090] Please refer to Figure 10 , the step of folding the packaging film 200' in half further includes:

[0091] S204: On the width direction of the packaging film 200', fold the packaging film 200' along the geometric center line of the packaging film 200'. Wherein, the geometric center line of the packaging film 200' refers to that when observing along the thickness direction of the packaging film 200', there is a center line on the width direction of the packaging film 200', and this center line divides the surface of the packaging film 200' into two parts with equal areas and symmetric about this center line.

[0092] S30: Seal the part of the bag body 207 between two adjacent first pits 206 to separate the two adjacent first pits 206.

[0093] S40: Open a liquid injection port 2071 on the bag body 207, and the liquid injection port 2071 communicates with the liquid injection cavity 210.

[0094] S50: Inject the electrolyte into all the battery cell cavities 201 through the liquid injection port 2071.

[0095] S60: After the electrolyte liquefies, seal the bag body 207 at the liquid inlet port 209 to seal the battery cell cavity 201.

[0096] S70: Along the periphery of each battery cell cavity 201, divide the bag body 207 to obtain at least two soft-pack batteries 1000, and the part of the bag body 207 used to package the battery cell 100 forms the packaging bag of the soft-pack battery 1000.

[0097] That is, please refer to Figures 11 to 13, before folding the packaging film 200' in half, at least two first pits 206 need to be punched out on the packaging film 200'. The two first pits 206 are arranged perpendicular to the folding direction of the packaging film 200' to facilitate the formation of two offset battery cell cavities 201. In addition, the part between the two first pits 206 of the same bag 207 needs to be encapsulated to separate the two first pits 206. That is, the encapsulation here does not need to completely separate the bag 207, but only needs to separate the two first pits 206, so that the two battery cell cavities 201 communicate with the same liquid injection cavity 210, and the electrolyte can be injected into the two battery cell cavities 201 through the same liquid injection port 2071 to improve production efficiency. In addition, by dividing the bag 207 along the periphery of the battery cell cavity 201, at least two soft-pack batteries 1000 can be obtained simultaneously, thereby improving production efficiency. And the two soft-pack batteries 1000 obtained by cutting are symmetrically placed, so that the third sealing edge 205 of one soft-pack battery 1000 and the third sealing edge 205 of the other soft-pack battery 1000 are formed simultaneously, reducing the unbonded area at the edge of the packaging film 200', and enabling both soft-pack batteries 1000 to have the effects brought by the above-mentioned third sealing edge 205, which will not be elaborated here again.

[0098] In addition, the following explanations need to be made for liquid injection and formation: The manufacture of the soft-pack battery 1000 needs to go through the processes of liquid injection, standing, and formation in sequence. Among them, liquid injection refers to injecting the electrolyte into the bag 207 of the soft-pack battery 1000. Standing is to statically place the soft-pack battery 1000 for a period of time after liquid injection, and the standing time is usually between 8 and 72 hours; the purpose of standing is to make the electrodes in the soft-pack battery 1000 fully wetted by the electrolyte, so as to facilitate the formation of a uniform and dense solid electrolyte interface (SEI) film on the surface of the electrodes during the subsequent formation process. Formation refers to the first charging of the manufactured lithium ions, aiming to form a passivation layer on the surface of the electrodes, that is, the above-mentioned SEI film; the formation of the SEI film can well prevent the active substances from collapsing and falling off, ensuring the excellent charge and discharge performance and long service life of the soft-pack battery 1000. The existence of these three processes makes the manufacturing cycle of the soft-pack battery 1000 longer; and the manufacturer also needs to prepare additional space and devices for standing the soft-pack battery 1000, such as factories, shelves, etc.

[0099] In some embodiments, please refer to Figures 14 to 16 , for the step of punching at least two first pits 206 on the S202 packaging film 200', it further includes:

[0100] S2021: For the packaging film 200', at least one second pit 213 is also punched out. The second pit 213 and one of the first pits 206 are jointly arranged in the first area or the second area.

[0101] For the step of folding the packaging film 200' in S204, it further includes:

[0102] S2041: After the packaging film 200' is folded in half, the first pit 206 and the second pit 213 in the first region are docked and jointly form a battery cell cavity 201; or, the first pit 206 and the second pit 213 in the second region are docked and jointly form a battery cell cavity 201.

[0103] Please refer to Figure 14 , by setting the second pit 213, on the one hand, a battery cell cavity 201 formed by docking the first pit 206 and the second pit 213, and another battery cell cavity 201 surrounded by the first pit 206 and other regions of the packaging film 200' are formed, thereby improving the dimensional design flexibility of the battery cell cavity 201. Optionally, setting the second pit 213 can enable the first pit 206 and the second pit 213 to be configured as pits with different depths, so that the soft-pack battery 1000 prepared by it can adapt to different installation environments and achieve better structural strength. It can be understood that the depth of the second pit 213 can be different from the depth of the first pit 206. For example: the depth of one of the first pit 206 and the second pit 213 is 0, and the other is greater than 0, and at least part of them overlap and dock to form a special-shaped battery; or, the depths of the first pit 206 and the second pit 213 are not 0, and they are staggered to form ultra-short batteries with different thicknesses at the same time. Thus, the usage scenarios of the soft-pack battery 1000 provided in this application are increased.

[0104] Furthermore, please review Figure 7 , and combine with other drawings. The packaging film 200' is folded in half to form a folding edge 202. A pre-sealing edge 2072 is formed between the part between the first pit 206 in the first region and the first pit 206 in the second region. By setting the pre-sealing edge 2072, it is convenient to divide the two battery cell cavities 201 and the subsequent division of the two soft-pack batteries 1000. It should be noted that the pre-sealing edge 2072 is shorter in the direction perpendicular to the extension direction of the folding edge 202 compared to other sealing edges sealed in the same step, so as to reduce the situation that the pre-sealing edge 2072 completely separates the liquid injection cavity 210, so that the liquid injection cavity 210 can inject liquid into the two battery cell cavities 201 at the same time. Preferably, the pre-sealing edge 2072 evenly divides the packaging film 200', so that the liquid injection rate of the liquid injection cavity 210 into the two battery cell cavities 201 is equal, thereby preventing excessive electrolyte from being injected into one of the battery cell cavities 201, causing uneven distribution of the electrolyte, reducing the impact on the yield rate of the manufacture of the soft-pack battery 1000; and, reducing the impact of uneven electrolyte distribution on the electrical performance of a single soft-pack battery 1000.

[0105] Among them, please refer to Figure 17, and in combination with other attached drawings. S70: The step of dividing the bag body 207 along the periphery of each battery cell cavity 201 further includes:

[0106] S701: Along the folding direction of the packaging film 200', encapsulate both sides of the bag body 207 to form two first unsealed edges 2073, and encapsulate the pre-sealed edge 2072;

[0107] S702: Inject electrolyte into all the battery cell cavities 201 through the liquid injection port 2071;

[0108] S703: Parallel to the folding edge 202, encapsulate the edge of the battery cell cavity 201 opposite to the folding edge 202;

[0109] S704: Divide the liquid injection cavity 210 and the battery cell cavity 201.

[0110] For the above steps, the two first unsealed edges 2073 respectively form the first seal edges 203 of the two soft-pack batteries 1000 after division. The pre-sealed edge 2072 after division simultaneously forms the third seal edges 205 of the two soft-pack batteries 1000, and dividing the liquid injection cavity 210 and the battery cell cavity 201 can simultaneously form the second seal edges 204 of the two soft-pack batteries 1000. Among them, the lengths of the two first unsealed edges 2073 are greater than the length of the pre-sealed edge 2072, and when encapsulating the edge of the battery cell cavity 201 opposite to the folding edge 202, the encapsulated area should at least partially overlap with the pre-sealed edge 2072, thereby reducing the risk of liquid leakage. Among them, the "first unsealed edge 2073" means that at least part of the edge of the packaging film 200' on the side of the first unsealed edge 2073 away from the battery cell cavity 201 is separated.

[0111] It still needs to be noted that in the current process of directly encapsulating and secondarily cutting each seal edge, at the folding edge 202 and the adjacent seal edge, a corner-like redundant structure will be formed on the side close to the tab 102, and another corner-like redundant structure will be formed on the side far from the tab 102. Its principle is generated by the first unsealed edge 2073 after the encapsulation process and the folding process, which is likely to affect the structural strength, sealing effect, and thermal management of the soft-pack battery 1000, and will cause material waste. In the preparation method provided by the present application, since the third seal edge 205 is cut from the pre-sealed edge 2072, no corner-like redundant structure will be generated. That is, for a single soft-pack battery 1000, the above-mentioned corner-like redundant structure is reduced, which can improve the structural strength, sealing effect of the soft-pack battery 1000, improve thermal management, and reduce material waste.

[0112] For S70: The step of dividing the bag body 207 further includes: dividing the bag body 207 along the pre-sealing edge 2072 to obtain at least two soft-pack batteries 1000. This reduces the number of encapsulation times and cutting times, simplifies the process flow, and improves production efficiency.

[0113] For the above pre-sealing edge 2072, along the direction parallel to the folding edge 202, the width D of the pre-sealing edge 2072 satisfies: 1.8 mm ≤ D ≤ 15 mm. Optionally, the width of the pre-sealing edge 2072 can be twice the width of the third sealing edge 205 of each soft-pack battery 1000. It can be understood that when the width of the pre-sealing edge 2072 is less than 1.8 mm, defects such as poor sealing effect and affecting the structural strength of the soft-pack battery 1000 are likely to occur, while when the width of the pre-sealing edge 2072 is greater than 15 mm, defects such as material waste and large size of the soft-pack battery 1000 are likely to occur.

[0114] Please refer to Figure 18 , and in combination with other drawings. For S202: The step of providing the packaging film 200' and punching out at least two first pits 206 in the packaging film 200' further includes: The packaging film 200' has a first folding part 211 and a second folding part 212;

[0115] S2021: Punch out at least two first pits 206 in at least one of the first folding part 211 and the second folding part 212, and one of the first pits 206 is located in the first area and the other first pit 206 is located in the second area. This can effectively improve the flexibility of the setting of the first pits 206 and simplify the manufacturing process.

[0116] Furthermore, for S20: The step of folding the packaging film 200' in half and encapsulating the edges of the folded packaging film 200' to form a bag body 207 with a cavity 208 inside further includes:

[0117] Please refer to Figure 19 , and in combination with other drawings. S2022: Stack the first folding part 211 and the second folding part 212, and encapsulate the peripheries of the first folding part 211 and the second folding part 212. It should be noted that "stacking the first folding part 211 and the second folding part 212" means that the first folding part 211 is folded relative to the second folding part 212 and overlapped along the thickness direction of the packaging film 200', so that when encapsulating the peripheries of the first folding part 211 and the second folding part 212, the first folding part 211 and the second folding part 212 can be encapsulated and cut at the same time, thereby reducing the relative offset between the first folding part 211 and the second folding part 212 and affecting the placement of the tab 102.

[0118] Preferably, the area of the first folding part 211 is equal to the area of the second folding part 212, so that the first folding part 211 and the second folding part 212 can completely coincide after being folded, making the first folding part 211 and the second folding part 212 receive uniform force during encapsulation, with no wrinkles at the melting and bonding interface, improving the airtightness; it can reduce the difference in local thickness caused by misalignment between the first folding part 211 and the second folding part 212, and slow down the penetration of the electrolyte along the gap between the first folding part 211 and the second folding part 212; it can withstand a higher bending moment and is suitable for high-vibration scenarios, such as smart devices with vibration functions, medical implant devices, or electric vehicles, etc.

[0119] Next, in combination with the above preparation method, the packaging film 200' provided in the present application will be further described.

[0120] Further, for S70: the step of dividing the bag body 207 along the periphery of each battery cell cavity 201 to obtain at least two soft-pack batteries 1000 further includes:

[0121] The soft-pack battery 1000 satisfies one of the following conditions:

[0122] a) For two soft-pack batteries 1000 divided from the same bag body 207, for at least one soft-pack battery 1000, the anode tab 1021 of the tab 102 is close to the folding edge 202, and the cathode tab 1022 of the tab 102 is far from the folding edge 202.

[0123] b) For two soft-pack batteries 1000 divided from the same bag body 207, for the two soft-pack batteries 1000, the anode tab 1021 of the tab 102 is far from the folding edge 202, and the cathode tab 1022 of the tab 102 is close to the folding edge 202.

[0124] It should be noted that please refer to Figures 20 to 22, and combined with other drawings. "The soft-pack battery 1000 satisfies one of the following conditions" means that the characteristics obtained by combining two soft-pack batteries 1000 formed by the same packaging film 200' are as follows: in the two soft-pack batteries 1000 divided from the same bag body 207, the third sealing edges 205 of the two soft-pack batteries 1000 are butted, the anode pole ear 1021 of the pole ear 102 of one soft-pack battery 1000 is close to the folding edge 202, and the cathode pole ear 1022 is far away from the folding edge 202, and the cathode pole ear 1022' of the pole ear 102 of the other soft-pack battery 1000 is close to the folding edge 202, and the anode pole ear 1021' is far away from the folding edge 202, that is, the two soft-pack batteries 1000 are rotationally symmetrical along the geometric midpoint of one of the third sealing edges 205, so that the position of the pole ear 102 is convenient when the pole ear 102 is placed in the battery cell cavity 201, reducing the impact on the structural strength and electrical properties of the pole ear 102. In other embodiments, in two soft-pack batteries 1000 divided from the same bag body 207, the third sealing edges 205 of the two soft-pack batteries 1000 are butt-jointed, the anode pole ear 1021 of the pole ear 102 of one soft-pack battery 1000 is close to the folding edge 202, and the cathode pole ear 1022 is far away from the folding edge 202, and the anode pole ear 1021' of the pole ear 102 of the other soft-pack battery 1000 is close to the folding edge 202, and the cathode pole ear 1022' is far away from the folding edge 202, that is, the two soft-pack batteries 1000 are symmetrical along the midline of the third sealing edge 205 of one of them.

[0125] In some embodiments, for the packaging film 200'. The second folding portion 212 includes a first portion 2121 and a second portion 2122, and the first portion 2121 is connected to the first folding portion 211. The first pit provided in the second folding portion 212 is located in the first portion 2121. The first pit provided in the first folding portion 211 is located on the portion of the first folding portion 211 used to reset with the first portion 2121. The second portion 2122 and the first folding portion 211 enclose a liquid injection cavity 210, and the liquid injection cavity 210 is used to inject electrolyte into the first pit. It can be understood that the boundary of the first portion 2121 can be divided into the side portions where the first folding portion 211 and the second folding portion 212 are folded relative to each other, the two sides of the second folding portion 212 away from the battery cell cavity 201, and the side portions of the first pit 206 away from the folding edge 202; accordingly, the area of ​​the second folding portion 212 outside the first portion 2121 is the second portion 2122. The first portion 2121 and the first folded portion 211 together form the packaging bag 200 , and the second portion 2122 and the first folded portion 211 together form a liquid injection cavity 210 in the bag body 207 for injecting liquid.

[0126] Further, the first folding portion 211, the first part 2121, and the second part 2122 are arranged in sequence along the first direction; and / or, at least two first pits 206 are arranged in sequence along the second direction. This facilitates the formation of the battery cell cavity 201 and the liquid injection cavity 210 communicating with the battery cell cavity 201. The two first pits 206 are arranged in sequence along the second direction, so that the distances between the battery cell cavity 201 formed by the two first pits 206 and the liquid injection cavity 210 are equal, enabling the same liquid injection rate of the electrolyte, improving the yield and production efficiency of the product.

[0127] It should be noted that, for specific reference, Figure 20 , and in combination with other attached drawings, during the liquid injection process, a suction nozzle is required to suck open both sides of the bag body 207 to facilitate the injection of the electrolyte into the liquid injection cavity 210 by the liquid injection device at the liquid injection port. In the figure, the semi - circles and columnar geometric figures on both sides of the liquid injection cavity 210 are schematic diagrams of the suction nozzle, and the geometric figure on the side of the liquid injection port 2071 away from the tab 102 is a schematic diagram of the liquid injection device. The minimum diameter of the suction nozzle used in the liquid injection process is 12 mm. Therefore, when the bag body 207 is expanded, the bag body 207 still needs to have some margin to facilitate the suction nozzle to expand the bag body 207 for the liquid injection device to inject the liquid.

[0128] Further, the number of the first pits 206 is the same as that of the second pits 213, and the first pits 206 and the second pits 213 are butt - jointed one by one. Thus, an asymmetric battery cell cavity 201 on both sides is formed to prepare a special - shaped battery, so as to adapt to different battery requirements.

[0129] Testing method:

[0130] Provide a soft - package battery 1000;

[0131] Provide the third seal 205 during the manufacturing process of the soft - package battery 1000;

[0132] Cut the third seal 205 into multiple strip - shaped samples with a length of 4 mm;

[0133] Put the cut - up third seal 205 into a tensile testing machine;

[0134] Use the tensile testing machine to clamp at least two sides of the third seal 205;

[0135] Keep the two sides on the same plane;

[0136] Operate the tensile testing machine to conduct the test;

[0137] Pull the sample until the third seal 205 is pulled apart

[0138] Record the tensile force value when the third seal 205 is pulled apart, with the unit (N).

[0139] Combined with the above test method, stress testing is performed on the third edge seal 205;

[0140] Example group: The preset encapsulation thickness for all examples in this test is 0.18 mm.

[0141] Example 1: The width of the third edge seal 205 is 0.9 mm;

[0142] Example 2: The width of the third edge seal 205 is 1.0 mm;

[0143] Example 3: The width of the third edge seal 205 is 1.1 mm;

[0144] Example 4: The width of the third edge seal 205 is 1.2 mm;

[0145] Example 5: The width of the third edge seal 205 is 2.0 mm;

[0146] Example 6: The width of the third edge seal 205 is 8.0 mm;

[0147] Example 7: The width of the third edge seal 205 is 13.0 mm;

[0148] Example 8: The width of the third edge seal 205 is 14.0 mm;

[0149] Example 9: The width of the third edge seal 205 is 15.0 mm;

[0150] Example 10: The width of the third edge seal 205 is 0.5 mm;

[0151] Example 11: The width of the third edge seal 205 is 18.0 mm.

[0152] The results are as shown in Table 1 below:

[0153] Width / mm Tensile force / N Example 1 0.9 4.1 Example 2 1.0 11.3 Example 3 1.1 11.8 Example 4 1.2 12.4 Example 5 2.0 17.1 Example 6 8.0 66.6 Example 7 13.0 80.5 Example 8 14.0 108.6 Example 9 15.0 108.9 Example 10 0.5 2.2 Example 11 18.0 120.6

[0154] Table 1

[0155] In summary, for the results obtained in Table 1, in the direction perpendicular to the extension of the tab 102, the third seal 205 has better tensile force bearing capacity when the width d is between 0.9 mm and 15 mm, higher structural strength, can maintain a better sealing effect, and can maintain the performance and safety of a single soft-pack battery 1000 when a single soft-pack battery 1000 is stressed or the packaging bag 200 expands; among them, by combining the ratios of the width d of the third seal 205 to the tensile force magnitude in Examples 1 to 2, the ratios of the width d of the third seal 205 to the tensile force magnitude in Examples 2 to 7, and the ratios of the width d of the third seal 205 to the tensile force magnitude in Examples 7 to 9, it can be obtained that when the width of the third seal 205 is between 0.9 mm and 1 mm and between 13 mm and 14 mm, the sealing strength and tensile strength of the third seal 205 are improved significantly; while when the width of the third seal 205 is between 1.0 mm and 13.0 mm, the sealing strength and tensile strength of the third seal 205 are stable; and after the width of the third seal 205 is greater than 15 mm, the improvement in the sealing strength and tensile strength of the third seal 205 still exists but is not obvious; by comparing Examples 12 and 13, it can be obtained that when the width d of the third seal 205 is less than 0.9 mm, the sealing strength and tensile strength shown are relatively insufficient, but the third seal 205 with this thickness can cope with some electronic devices with relatively stable working environments; and when the width d of the third seal 205 is greater than 15 mm, the gain in packaging strength brought by the increase in the width of the third seal 205 is not proportional to the size loss. Therefore, in the optional technical solution provided in this application, the width d of the third seal 205 satisfies 0.9 mm ≤ d ≤ 15 mm, which can bring the technical effects described above. Preferably, when the width d of the third seal 205 satisfies 1 mm ≤ d ≤ 2 mm, on the basis of meeting the minimum packaging strength, the third seal 205 can obtain a better energy density gain, and the gain in packaging strength brought by the increase in the width of the third seal 205 is relatively large. That is, the third seal 205 in this interval can further reflect the technical effects described above brought by the technical solution provided in this application. For the technical effects brought by the third seal 205, reference can be made to the above text, and details are not repeated here.

[0156] In addition, since the third seal 205 is obtained by cutting the pre-seal 2072, when the width D of the pre-seal 2072 is greater than or equal to 1.8 mm, the pre-seal 2072 meets the minimum packaging strength. At this time, the pre-seal 2072 can pass the drop test. That is, in the above embodiments provided by the present application, the two soft-pack batteries 1000 with the pre-seal 2072 can be directly put into use, or the two soft-pack batteries 1000 can be obtained by cutting the pre-seal 2072. When the width D of the pre-seal 2072 is greater than 15 mm, since it already has sufficient packaging strength, the excessive width is likely to cause a decrease in energy density and size limitations, and is also likely to cause waste of materials. Therefore, when the width D of the pre-seal 2072 satisfies 1.8 mm ≤ D ≤ 15 mm, it can meet the packaging strength, provide a better energy density of the soft-pack battery 1000, obtain a smaller size of the soft-pack battery 1000, and reduce waste of materials.

[0157] The present application aims to provide a soft-pack battery 1000, which includes a battery cell 100 and a packaging bag 200. The battery cell 100 includes an electrode assembly 101 and a tab 102. The packaging bag 200 is provided with a battery cell cavity 201, the electrode assembly 101 is received in the battery cell cavity 201, the tab 102 extends out of the battery cell cavity 201 from the electrode assembly 101, and the edge of the packaging bag 200 is configured as a folding edge 202, a first seal 203, a second seal 204, and a third seal 205 that are sequentially connected. The first seal 203 and the folding edge 202 are adjacent to each other, the first seal 203 and the third seal 205 are opposite to each other, the tab 102 extends at least partially out of the first seal 203, and the second seal 204 and the folding edge 202 are opposite to each other. There is a seal on the packaging bag 200 on the side of the third seal 205 facing away from the battery cell cavity 201, and the seal extends from the direction in which the tab 102 extends out of the battery cell cavity 1000 to the edge of the third seal 205. There are seals on the packaging bag 200 on the sides of the first seal 203 and the second seal 204 facing away from the battery cell cavity 201. In the above technical solution, during the process of forming the packaging bag 200, one edge is folded to form the folding edge 202, and the first seal 203, the second seal 204, and the third seal 205 are sealed so that the three together with the folding edge 202 enclose the battery cell cavity 201, where the third seal 205 is a sealed edge with a seal and is adjacent to the folding edge 202. On the one hand, the third seal 205 having a seal reduces the size of the soft-pack battery 1000 in the direction where the third seal 205 is provided, facilitating the structural design of the soft-pack battery 1000 and improving the compactness of the overall structure; on the other hand, the third seal 205 and the folding edge 202 are adjacent to each other, which can reduce the angular redundant structure, improve the structural strength, sealing effect, and thermal management of the soft-pack battery, and reduce material waste.

[0158] Based on the same inventive concept, the present application also provides a method for manufacturing the above-mentioned soft-pack battery 1000. For the specific steps of the manufacturing method of the soft-pack battery 1000, reference can be made to the above text, and details are not repeated here.

[0159] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than limiting them; under the concept of the present application, the technical features in the above embodiments or different embodiments can also be combined, and the steps can be implemented in any order, and there are many other changes in different aspects of the present application as described above. For the sake of brevity, they are not provided in detail; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A soft pack battery, characterized in that: Including battery cells and packaging bags; The battery cell comprises an electrode assembly and a tab; The packaging bag is provided with a battery cell cavity, the electrode assembly is accommodated in the battery cell cavity, the electrode tab extends out of the battery cell cavity from the electrode assembly, the edge of the packaging bag is configured as a folded edge, a first edge seal, a second edge seal and a third edge seal connected in sequence, the third edge seal and the folded edge are arranged adjacent to each other, the third edge seal is arranged opposite to the first edge seal, the electrode tab at least partially extends out from the first edge seal, and the second edge seal is arranged opposite to the folded edge; The packaging bag on the side of the first sealed edge and the second sealed edge facing away from the battery cell cavity is sealed; The packaging bag on the side of the third edge seal facing away from the battery cell cavity is sealed, and the seal of the third edge seal extends away from the direction in which the tab extends out of the battery cell cavity to the edge of the third edge seal.

2. The soft pack battery according to claim 1, characterized in that: Along the direction in which the tab extends out of the cell cavity, the length of the cell is less than or equal to 15 mm 。 3. The soft pack battery according to claim 1, characterized in that: The first edge sealing, the second edge sealing and the third edge sealing satisfy at least one of the following conditions: a) the first edge seal is folded toward the cavity of the battery cell cavity; b) the second edge seal is folded toward the cavity of the battery cell cavity; c) The third edge seal is folded toward the cavity of the battery cell cavity.

4. The soft pack battery according to claim 1, characterized in that: The packaging bag comprises a polymer adhesive layer, and the seal of the third edge seal is formed by bonding the polymer adhesive layer.

5. The soft pack battery according to claim 1, characterized in that: The packaging bag is provided with at least one first pit, and the first pit and other areas outside the first pit together enclose the battery cell cavity, and the battery cell cavity is used to accommodate the electrode assembly.

6. The soft pack battery according to claim 5, characterized in that: In the direction in which the electrode tab extends out of the battery cell cavity, a width d of the third edge seal satisfies 0.9 mm ≤ d ≤ 15 mm.

7. The soft pack battery according to claim 6, characterized in that: In the direction in which the electrode tab extends out of the battery cell cavity, a width d of the third edge seal satisfies 1 mm ≤ d ≤ 2 mm.

8. A method for preparing a soft-pack battery according to any one of claims 1 to 7, characterized in that: include: Providing at least two battery cells, each of the battery cells comprising an electrode assembly and two electrode tabs connected to the electrode assembly; A packaging film is provided, the packaging film is folded in half around the width direction of the packaging film, and the periphery of the folded packaging film is sealed to form a bag body, the bag body has a cavity, and the packaging film is also provided with at least two battery cell cavities with liquid inlets in the cavity, and the bag body is also formed with a liquid injection cavity, and the battery cell cavity is connected with the liquid injection cavity through the liquid inlet.

9. The preparation method according to claim 8, characterized in that: The step of providing a packaging film further comprises: Punching at least two first pits in the packaging film, one of the first pits is located in the first area, and the other first pit is located in the second area, and the arrangement direction of the first area and the second area is perpendicular to the folding direction of the packaging film; Placing one of the battery cells into one of the first recesses; The step of folding the packaging film in half further comprises: Folding the packaging film in half along the geometric center line of the packaging film in the width direction of the packaging film; Encapsulating the portion of the bag body between two adjacent first recesses so as to separate the two adjacent first recesses; A liquid injection port is provided in the bag body, and the liquid injection port is communicated with the liquid injection cavity; Injecting electrolyte into the battery cell cavity through the injection port; After the formation, the bag body is sealed at the liquid inlet to close the battery cell cavity; The bag body is divided along the periphery of each of the battery cell cavities to obtain at least two soft-pack batteries, and the portion of the bag body used for packaging the battery cells forms a packaging bag for the soft-pack battery.

10. The preparation method according to claim 9, characterized in that: The step of punching at least two first pits out of the packaging film further comprises: At least one second recess is punched out of the packaging film, and the second recess and one of the first recesses are arranged together in the first area or the second area; The step of folding the packaging film in half further comprises: After the packaging film is folded in half, the first pit and the second pit in the first area are butted together to form a battery cell cavity; or the first pit and the second pit in the second area are butted together to form a battery cell cavity.

11. The preparation method according to claim 9, characterized in that: folding the packaging film in half to form a folded edge; forming a pre-sealed edge at a portion between the first recess in the first region and the first recess in the second region; The step of dividing the bag body along the periphery of each of the battery cell cavities further comprises: In the folding direction of the packaging film, two side edges of the bag body are sealed to form two first unsealed edges, and the pre-sealed edges are sealed; Injecting electrolyte into the battery cell cavity through the injection port; In parallel with the folding edge, encapsulating the edge of the battery cell cavity relative to the folding edge; The liquid injection cavity and the battery core cavity are divided.

12. The preparation method according to claim 11, characterized in that: The step of dividing the bag further includes: The bag body is divided along the pre-sealed edge to obtain at least two soft-pack batteries.

13. The preparation method according to claim 11, characterized in that: The step of providing a packaging film and punching at least two first pits in the packaging film further comprises: The packaging film has a first folding portion and a second folding portion; Punching out the at least two first recesses in at least one of the first folded portion and the second folded portion, wherein one of the first recesses is located in the first region and the other of the first recesses is located in the second region; The step of folding the packaging film in half and sealing the edges of the folded packaging film to form a bag body having a cavity further comprises: The first folded portion and the second folded portion are overlapped, and peripheries of the first folded portion and the second folded portion are sealed.

14. The preparation method according to claim 13, characterized in that: The step of dividing the bag body along the periphery of each of the battery cell cavities to obtain at least two of the soft-pack batteries further includes: The soft pack battery meets one of the following conditions: a) two soft-pack batteries separated from the same bag body, wherein the anode tab of at least one of the soft-pack batteries is close to the folding edge, and the cathode tab of the tab is far away from the folding edge; b) Two soft-pack batteries separated from the same bag body, wherein the anode tabs of the two soft-pack batteries are far away from the folding edge, and the cathode tabs of the two soft-pack batteries are close to the folding edge.

15. The preparation method according to claim 13, characterized in that: For the packaging film: The second folded portion includes a first part and a second part, and the first part is connected to the first folded portion; The first recess provided in the second folded portion is located in the first portion; The first recess provided on the first folded portion is located on a portion of the first folded portion that is arranged to overlap with the first portion; The second portion and the first folded portion enclose a liquid injection cavity, and the liquid injection cavity is used to inject electrolyte into the first pit.

16. The preparation method according to claim 15, characterized in that: The first folding portion, the first part and the second part are arranged in sequence along the length direction of the packaging film; and / or, The at least two first pits are arranged sequentially along the width direction of the packaging film.

17. The preparation method according to claim 13, characterized in that: The area of ​​the first folded portion is equal to the area of ​​the second folded portion.

18. The preparation method according to claim 10, characterized in that: For the packaging film: Along the width direction of the packaging film, the sum of the widths of the two first pits is smaller than the width of the packaging film; The width of the packaging film is greater than or equal to 15 mm.

19. The preparation method according to claim 10, characterized in that: The number of the first pits is the same as the number of the second pits, and the first pits and the second pits are connected one by one.

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