Thermal shrinkage film and preparation method thereof, battery cell and manufacturing method thereof, battery and power utilization device

Abstract

The invention provides a thermal shrinkage film and a preparation method thereof, a battery cell and a manufacturing method thereof, a battery and a power utilization device, and relates to the technical field of battery production, the thermal shrinkage film comprises a base film and a support plate; the base film is configured to be used for wrapping the naked battery cell and is provided with a first surface and a second surface which can be arranged opposite to the naked battery cell in a first direction; supporting plates are arranged on the first surface and the second surface, the first direction is perpendicular to the second direction, and the second direction is the tab leading-out direction of the naked battery cell. Therefore, when the bare battery cell is coated with the base film, the supporting plate can support the base film in the first direction to limit the shrinkage of the base film on the first surface and the second surface, so that the pressure applied to the bare battery cell when the base film is shrunk is reduced.

Description

Technical Field

[0001] This application relates to the technical field of battery production, and in particular to a heat shrink film and its preparation method, a battery cell and its manufacturing method, a battery and an electrical device. Background Technology

[0002] In battery manufacturing, heat-shrink film is typically used to wrap bare battery cells to improve their water resistance and sealing. However, the heat-shrink film exerts pressure on the bare cells when it shrinks under heat, with the edges experiencing the greatest pressure. This makes the edges of the bare cells prone to damage, leading to a decrease in battery yield. Summary of the Invention

[0003] This application provides a heat shrink film and its preparation method, a battery cell and its manufacturing method, a battery and an electrical device, aiming to solve the problem that existing heat shrink films easily damage bare battery cells.

[0004] To address the aforementioned issues, this application provides a heat-shrinkable film comprising: a base film and a support plate; the base film is configured to cover a bare battery cell and has a first surface and a second surface that are disposed opposite to the bare battery cell in a first direction; the support plate is provided on both the first and second surfaces, the first direction is perpendicular to the second direction, and the second direction is the tab lead-out direction of the bare battery cell.

[0005] In the above scheme, by setting the base film for coating the bare battery cell to have a first surface and a second surface that are disposed opposite to the bare battery cell in a first direction, and the first surface and the second surface are provided with support plates in the first direction, the support plates can support the base film in the first direction when the base film coats the bare battery cell, so as to limit the shrinkage of the base film on the first surface and the second surface, thereby reducing the pressure applied to the bare battery cell when the base film shrinks. This is beneficial to reduce the probability of damage to the bare battery cell during the coating process.

[0006] In one embodiment, the thermal shrinkage rate of the base film in the second direction is 0-15%.

[0007] Therefore, by setting the thermal shrinkage rate of the base film in the second direction to 0-15%, and the second direction being the tab lead-out direction of the bare cell, the base film has a small thermal shrinkage rate in the second direction. This helps to reduce the probability of wrinkles appearing when the base film shrinks in the second direction due to the base film being unrestrained or weakly restrained.

[0008] In one embodiment, the thermal shrinkage rate of the base film in the first direction is 30-60%.

[0009] Therefore, by setting the thermal shrinkage rate of the base film in the first direction to 30-60%, the base film has a large size in the first direction, so as to ensure that the base film can form a sufficiently large space to accommodate the bare battery cell, thereby facilitating the base film 110 to shrink and cover the bare battery cell when heated.

[0010] In one embodiment, the thickness of the support plate in the first direction is 0.1-1 mm.

[0011] Therefore, by setting the thickness of the support plate in the first direction to 0.1-1mm, the support plate can maintain a relatively thin thickness, thereby reducing the impact of the support plate on the cell size in the first direction.

[0012] In one embodiment, the support plate is located within the coverage area of ​​the bare cell's orthographic projection in a first direction.

[0013] Therefore, by setting the support plate within the coverage area of ​​the bare cell's orthogonal projection in the first direction, the edge of the support plate can be flush with or lower than the edge of the bare cell, so as to avoid the support plate obstructing the base film from covering the bare cell.

[0014] In one embodiment, the support plate is made of plastic.

[0015] Therefore, by making the support plate out of plastic, the support plate can be electrically isolated from the bare battery cell.

[0016] In one embodiment, the support plate is made of polycarbonate, polyamide, or polyphenylene sulfide.

[0017] Therefore, by setting the material of the support plate to polycarbonate, polyamide or polyphenylene sulfide, the support plate can also have good impact resistance and high temperature resistance.

[0018] In one embodiment, the base film comprises: 70-85% by weight of polyolefin resin, 10-20% by weight of inorganic ceramic particles, and 5-10% by weight of toughening agent.

[0019] Therefore, by setting the base film to include: 70-85% polyolefin resin by mass, 10-20% inorganic ceramic particles by mass, and 5-10% toughening agent by mass, the base film can have the property of shrinking under heat, so as to achieve the coating of the bare battery cell by the base film.

[0020] In one embodiment, the polyolefin resin includes high-density polyethylene or linear low-density polyethylene.

[0021] Therefore, by setting the polyolefin resin to include high-density polyethylene or linear low-density polyethylene, the base film can have the high mechanical strength of high-density polyethylene material or the high toughness of linear low-density polyethylene material.

[0022] In one embodiment, the inorganic ceramic particles include at least one of aluminum oxide and silicon dioxide.

[0023] Therefore, by incorporating inorganic ceramic particles including at least one of aluminum oxide and silicon dioxide, it is helpful to improve the thermal stability and mechanical strength of the base film.

[0024] In one embodiment, the toughening agent comprises: ethylene-vinyl acetate copolymer.

[0025] Therefore, by including ethylene-vinyl acetate copolymer as a toughening agent, the flexibility of the base film can be improved.

[0026] In one embodiment, the base film has a thermal shrinkage rate of 50% in the first direction and a thermal shrinkage rate of 10% in the second direction.

[0027] Therefore, by setting the base film's thermal shrinkage rate to 50% in the first direction and 10% in the second direction, the base film can not only maintain a smaller thermal shrinkage rate in the second direction to reduce the probability of wrinkles when shrinking in the second direction, but also maintain a larger size in the first direction to ensure that the base film can form a sufficiently large space to accommodate the bare battery cell.

[0028] This application also provides a method for preparing a heat-shrinkable film, which includes: providing a base film having a first surface and a second surface; providing a support plate and bonding the support plate to the first surface and the second surface respectively.

[0029] In the above scheme, by setting a support plate to be bonded to the first and second surfaces of the base film, when the base film surrounds and forms a space to accommodate the bare battery cell, the support plate can be set to correspond with the bare battery cell at the same time to protect the bare battery cell, thereby reducing the probability of the bare battery cell being damaged by pressure from the base film.

[0030] In one embodiment, the step of providing the base film includes: mixing raw materials and then melt-extruding to obtain a cast sheet; stretching the cast sheet in a first direction and a second direction respectively; and heat-setting and cooling the stretched cast sheet to obtain the base film.

[0031] Therefore, by setting the cast sheet to be stretched in the first direction and the second direction respectively, the cast sheet can have a predetermined shrinkage rate in the first direction and the second direction to meet the requirements of the base film shrinkage due to heat.

[0032] In one embodiment, the shrinkage rate of the stretched cast sheet is controlled at 30-60% in the first direction and at 0-15% in the second direction.

[0033] Therefore, by setting the heat shrinkage rate of the base film to 30-60% in the first direction and 0-15% in the second direction, the base film can not only maintain a small heat shrinkage rate in the second direction to reduce the probability of wrinkles when the base film shrinks in the second direction, but also maintain a large size in the first direction to ensure that the base film can form a sufficiently large space to accommodate the bare battery cell.

[0034] This application also provides a method for manufacturing a battery cell, the method comprising: providing a bare battery cell and the aforementioned heat-shrinkable film; placing the bare battery cell within a space formed by the base film, with the bare battery cell positioned between support plates on a first surface and a second surface; preheating the placed base film and bare battery cell; hot-pressing the preheated base film and bare battery cell to shrink the base film to cover the bare battery cell and cause the support plate to adhere to the bare battery cell; and cooling and shaping the hot-pressed base film and bare battery cell.

[0035] In the above scheme, by providing support plates on the first and second surfaces of the base film, the support plates can support the pressure applied by the base film to the bare cell when the base film and the bare cell are hot-pressed, thereby reducing the probability of damage to the edges of the bare cell due to pressure and improving the production yield of the cell.

[0036] In one embodiment, the size of the unfolded base film in the first direction is at least 50% larger than the size of the bare cell in the first direction; and the size of the unfolded base film in the second direction is at least 30% larger than the size of the bare cell in the second direction.

[0037] Therefore, by setting the size of the unfolded base film in the first direction to be at least 50% larger than the size of the bare cell in the first direction, and the size in the second direction to be at least 30% larger than the size of the bare cell in the second direction, the base film can be set up to form a sufficiently large space for placing the bare cell, so that the base film can be fitted onto the bare cell for subsequent hot pressing.

[0038] This application also provides a battery cell, which is manufactured by the above-described battery cell manufacturing method; the bare battery cell has a side surface parallel to the second direction, a base film is covered on the side surface, and the support plates on the first surface and the second surface are in contact with the side surface.

[0039] In the above scheme, by setting a base film to cover the side surface of the bare cell, and the support plate to contact the side surface, the support plate can protect the edge of the bare cell, thereby reducing the probability of damage to the edge of the bare cell caused by the pressure applied by the base film, thus improving the reliability and service life of the cell.

[0040] This application also provides a battery comprising: at least one of the above-described cells.

[0041] In the above scheme, including at least one highly reliable and long-life battery cell in the battery also helps to improve the reliability and lifespan of the battery.

[0042] This application also provides an electrical device, which includes the battery described above.

[0043] In the above scheme, including a battery with high reliability and long service life in the electrical device also helps to improve the reliability and service life of the electrical device. Attached Figure Description

[0044] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort, wherein: Figure 1 This is a top view of the heat-shrinkable film and bare battery cell disclosed in the embodiments of this application; Figure 2 yes Figure 1 A schematic diagram of a bare battery cell covered with heat-shrinkable film. Figure 3 yes Figure 2 A magnified view of a portion of point A in the middle; Figure 4 This is a schematic flowchart of the method for preparing heat-shrinkable film disclosed in the embodiments of this application; Figure 5 yes Figure 4 The process flow diagram for providing the base film is provided; Figure 6 This is a schematic flowchart of the battery cell manufacturing method disclosed in the embodiments of this application; Figure 7 This is a schematic diagram of the battery structure disclosed in the embodiments of this application; Figure 8 This is a schematic diagram of the structure of the electrical device disclosed in the embodiments of this application.

[0045] The attached figures are labeled as follows: Heat shrink film 100, base film 110, first surface 111, second surface 112, support plate 120, bare cell 200, tab 201, side surface 210, battery 5, cell 10, housing 51, first part 511, second part 512, electrical device 1, controller 101, motor 102, first direction X, second direction Y, third direction Z. Detailed Implementation

[0046] It should be noted that, unless otherwise specified, the embodiments and technical features in the embodiments of this application can be combined with each other, and the detailed descriptions in the specific implementation should be understood as explanations of the purpose of this application and should not be regarded as undue limitations on this application.

[0047] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having” and any variations thereof are intended to cover non-exclusive inclusion.

[0048] In the description of the embodiments of this application, the technical terms "first", "second", "third", etc. are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features.

[0049] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0050] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application according to the specific circumstances.

[0051] In the description of the embodiments of this application, unless otherwise expressly specified and limited, the technical term "contact" should be interpreted broadly, and can be direct contact, contact through an intermediate medium layer, contact between two contacting parties with substantially no interaction force, or contact between two contacting parties with interaction force.

[0052] In some technical solutions, heat-shrink film is typically used to wrap the bare battery cell to improve its waterproof and moisture-proof performance, thereby enhancing its sealing. When the heat-shrink film shrinks and adheres tightly to the bare cell, the cell is subjected to pressure from the shrinkage. However, since most heat-shrink films shrink significantly in both the longitudinal and transverse directions, the bare cell also experiences considerable bidirectional pressure. This can lead to stress concentration at the edges of the bare cell, potentially causing electrode damage and / or separator rupture, ultimately affecting the cell's production yield.

[0053] To address the aforementioned technical problems, the heat-shrinkable film disclosed in this application provides a base film for wrapping a bare battery cell. This base film has a first surface and a second surface that are disposed opposite to the bare battery cell in a first direction. Both the first and second surfaces are provided with support plates in the first direction. This allows the support plates to support the base film in the first direction when the base film wraps the bare battery cell, thereby limiting the shrinkage of the base film on the first and second surfaces. This reduces the pressure applied to the bare battery cell when the base film shrinks, which helps to reduce the probability of damage to the bare battery cell during the wrapping process.

[0054] Please see Figures 1 to 3 , Figure 1 This is a top view of the heat-shrink film and bare battery cell disclosed in the embodiments of this application. Figure 2 yes Figure 1 A schematic diagram of the structure of a bare battery cell coated with heat-shrink film. Figure 3 yes Figure 2 A magnified view of a portion of point A in the middle.

[0055] like Figures 1 to 3 As shown, the heat shrink film 100 may include a base film 110 and a support plate 120. The base film 110 is configured to cover the bare battery cell 200 and has a first surface 111 and a second surface 112 that are disposed opposite to the bare battery cell 200 in a first direction X. The support plate 120 is provided on both the first surface 111 and the second surface 112. The first direction X is perpendicular to the second direction Y, and the second direction Y is the lead-out direction of the tab 201 of the bare battery cell 200.

[0056] The bare cell 200 can be used to manufacture a square battery, and the base film 110 can be formed to enclose a space for placing the bare cell 200, and can be thermally shrunk to cover the outer surface of the bare cell 200. In order to avoid the tabs 201 led out from the bare cell 200, the base film 110 can be arranged around the side surface 210 of the bare cell 200 parallel to the second direction Y, and can be thermally shrunk to cover the side surface 210.

[0057] After the base film 110 is heated and shrinks to cover the bare battery cell 200, the base film 110 has a first surface 111 and a second surface 112 that can be disposed opposite to the bare battery cell 200 in the first direction X. That is, the bare battery cell 200 is located between the first surface 111 and the second surface 112 in the first direction X, such that both the first surface 111 and the second surface 112 can be disposed opposite to the side surface 210.

[0058] Support plates 120 can be provided on both the first surface 111 and the second surface 112. When the base film 110 shrinks due to heat and covers the bare cell 200, both support plates 120 can contact the side surface 210 of the bare cell 200 and support the base film 110 in the first direction X to limit the shrinkage of the base film 110 on the first surface 111 and the second surface 112.

[0059] In the above scheme, by setting the base film 110 for covering the bare battery cell 200 to have a first surface 111 and a second surface 112 that are disposed opposite to the bare battery cell 200 in the first direction X, and both the first surface 111 and the second surface 112 are provided with support plates 120 in the first direction X, so that when the base film 110 covers the bare battery cell 200, the support plates 120 can support the base film 110 in the first direction X, thereby limiting the shrinkage of the base film 110 on the first surface 111 and the second surface 112, thereby reducing the pressure applied to the bare battery cell 200 when the base film 110 shrinks. This is beneficial to reduce the probability of damage to the bare battery cell 200 during the covering process.

[0060] like Figures 1 to 3 As shown, the thermal shrinkage rate of the base film 110 in the second direction Y is 0-15%.

[0061] Since the base film 110 mainly covers the side surface 210 of the bare cell 200, when the base film 110 shrinks due to heat, the base film 110 will lack constraint in the second direction Y, which makes it easy for the base film 110 to form wrinkles after shrinking in the second direction Y. The presence of wrinkles will cause inconsistent surface pressure during subsequent hot pressing of the base film 110, ultimately causing local lithium plating in the bare cell 200.

[0062] To reduce the probability of the base film 110 shrinking and forming wrinkles in the second direction Y, the thermal shrinkage rate of the base film 110 in the second direction Y in this embodiment can be 0-15%, so that the base film 110 can have a small thermal shrinkage rate in the second direction Y. Specifically, the thermal shrinkage rate of the base film 110 in the second direction Y can be 0%, 5%, 10%, or 15%.

[0063] In the above scheme, by setting the thermal shrinkage rate of the base film 110 in the second direction Y to 0-15%, and the second direction Y being the lead-out direction of the tab 201, the base film 110 has a small thermal shrinkage rate in the second direction Y. This helps to reduce the probability of wrinkles appearing when the base film 110 shrinks in the second direction Y due to the base film 110 being unrestrained or weakly restrained in the second direction Y.

[0064] like Figures 1 to 3 As shown, the thermal shrinkage rate of the base film 110 in the first direction X is 30-60%.

[0065] To facilitate the coating of the bare cell 200 by the base film 110, the heat shrinkage rate of the base film 110 in the first direction X in this embodiment can be 30-60%, so that the base film 110 can have a large heat shrinkage rate in the first direction X. Specifically, the heat shrinkage rate of the base film 110 in the first direction Y can be 30%, 40%, 50% or 60%.

[0066] In the above scheme, by setting the thermal shrinkage rate of the base film 110 in the first direction X to 30-60%, the base film 110 can have a large size in the first direction X, so as to ensure that the base film 110 can form a sufficiently large space to accommodate the bare cell 200, thereby facilitating the subsequent thermal shrinkage of the base film 110 to cover the bare cell 200.

[0067] It is understandable that the above descriptions of heat shrinkage rate refer to the heat shrinkage rate of the base film 110 in a flattened state, that is, the heat shrinkage rate of the base film 110 in a flattened state. Figure 1 In the illustrated state, the thermal shrinkage rate of the base film 110 in the first direction X can be 30-60%, while the thermal shrinkage rate in the second direction Y can be 0-15%. Simultaneously, when the base film 110 encloses a space to accommodate the bare battery cell 200, the shrinkage of a portion of the base film 110 corresponding to the first surface 111 and the second surface 112 in the first direction X can be transformed into shrinkage in the third direction Z, and the third direction Z can be perpendicular to the first direction X and the second direction Y.

[0068] In some embodiments, the base film has a thermal shrinkage rate of 50% in the first direction X and a thermal shrinkage rate of 10% in the second direction Y.

[0069] Therefore, by setting the base film 110 to have a heat shrinkage rate of 50% in the first direction X and a heat shrinkage rate of 10% in the second direction Y, the base film 110 can not only maintain a small heat shrinkage rate in the second direction Y to reduce the probability of wrinkles when the base film 110 shrinks in the second direction Y, but also maintain a large size in the first direction X to ensure that the base film 110 can form a sufficiently large space to accommodate the bare cell 200.

[0070] Furthermore, the base film 110 comprises: 70-85% polyolefin resin by mass, 10-20% inorganic ceramic particles by mass, and 5-10% toughening agent by mass.

[0071] Specifically, the base film 110 may include: 70% polyolefin resin, 20% inorganic ceramic particles, and 10% toughening agent by mass. Alternatively, the base film 110 may include: 75% polyolefin resin, 20% inorganic ceramic particles, and 5% toughening agent by mass. Or, the base film 110 may include: 85% polyolefin resin, 10% inorganic ceramic particles, and 5% toughening agent by mass. Of course, the mass percentages of the polyolefin resin, inorganic ceramic particles, and toughening agent can be adjusted according to requirements; these will not be listed individually in this embodiment.

[0072] In the above scheme, by setting the base film 110 to include: 70-85% polyolefin resin, 10-20% inorganic ceramic particles and 5-10% toughening agent by mass, the base film 110 can have the property of heat shrinkage, so as to achieve the coating of the bare cell 200 by the base film 110.

[0073] In some embodiments, the polyolefin resin includes high-density polyethylene or linear low-density polyethylene.

[0074] Therefore, by setting the polyolefin resin to include high-density polyethylene or linear low-density polyethylene, the base film 110 can have the high mechanical strength of high-density polyethylene material or the high toughness of linear low-density polyethylene material.

[0075] In some embodiments, the inorganic ceramic particles include at least one of aluminum oxide and silicon dioxide.

[0076] Therefore, by incorporating inorganic ceramic particles including at least one of aluminum oxide and silicon dioxide, the thermal stability and mechanical strength of the base film 110 can be improved.

[0077] In some embodiments, the toughening agent includes: ethylene-vinyl acetate copolymer.

[0078] Therefore, by including ethylene-vinyl acetate copolymer as a toughening agent, the flexibility of the base film 110 is improved.

[0079] It is understood that, in addition to the above embodiments, the raw materials of the base film 110 can also be adjusted according to the design requirements of the battery cell 10. It is only necessary that the base film 110 has heat shrinkability and can be used to coat the bare battery cell 200.

[0080] like Figures 1 to 3 As shown, the thickness of the support plate 120 in the first direction X is 0.1-1mm.

[0081] To reduce the impact of the support plate 120 on the size of the battery cell 10 in the first direction X, the thickness of the support plate 120 in the first direction X in this embodiment can be 0.1-1mm, so that the support plate 120 can not only support the base film 110, but also have a relatively thin thickness. Specifically, the thickness of the support plate 120 can be 0.1mm, 0.25mm, 0.5mm or 1mm.

[0082] In the above scheme, by setting the thickness of the support plate 120 in the first direction X to 0.1-1mm, the support plate 120 can maintain a relatively thin thickness, so as to reduce the impact of the support plate 120 on the size of the cell 10 in the first direction X.

[0083] like Figures 1 to 3 As shown, the support plate 120 is located within the coverage area of ​​the bare cell 200's orthogonal projection in the first direction X.

[0084] The dimension of the support plate 120 in the second direction Y can be less than or equal to the dimension of the bare cell 200 in the second direction Y, and the dimension of the support plate 120 in the third direction Z can also be less than or equal to the dimension of the bare cell 200 in the third direction Z, so that the edge of the support plate 120 can be flush with or recessed into the edge of the bare cell 200, ensuring that the support plate 120 can be located within the coverage area of ​​the orthogonal projection of the bare cell 200 in the first direction X. The support plate 120 can adopt a long strip-shaped design to ensure that the support plate 120 adheres to the side surface 210 of the bare cell 200 after the base film 110 is shrunk.

[0085] In the above scheme, by setting the support plate 120 within the coverage area of ​​the orthogonal projection of the bare cell 200 in the first direction X, the edge of the support plate 120 can be flush with or lower than the edge of the bare cell 200, so as to avoid the support plate 120 obstructing the base film 110 from covering the bare cell 200.

[0086] The support plate 120 is made of plastic, which allows it to maintain electrical isolation from the bare battery cell 200. Specifically, the support plate 120 can be made of polycarbonate, polyamide, or polyphenylene sulfide, giving it not only insulation properties but also good impact resistance and high-temperature resistance.

[0087] In some embodiments, the material of the support plate 120 can also be adapted to design requirements, as long as the support plate 120 has a certain rigidity to support the base film 110 and maintain electrical isolation from the bare cell 200.

[0088] Please see Figures 4 to 5 As shown, Figure 4 This is a schematic flowchart of the method for preparing heat-shrinkable film disclosed in the embodiments of this application. Figure 5 yes Figure 4 The diagram below shows the steps involved in creating the base film.

[0089] like Figure 4 As shown, the method for preparing the heat-shrinkable film provided in this application embodiment can be used to prepare the aforementioned heat-shrinkable film 100, and the method for preparing the heat-shrinkable film may include: S10 provides a base film, and the base film has a first surface and a second surface.

[0090] S20, a support plate is provided, and the support plate is bonded to the first surface and the second surface respectively.

[0091] The base film 110 may have the aforementioned first surface 111 and second surface 112, and adhesive may be coated on the first surface 111 and second surface 112, while the support plate 120 may be bonded to the first surface 111 and second surface 112 by adhesive. In this embodiment, the support plate 120 may be made of plastic, and the support plate 120 may be integrally manufactured by injection molding.

[0092] In some embodiments, in addition to applying adhesive to the first surface 111 and the second surface 112, adhesive may also be applied to the support plate 120 and the support plate 120 with adhesive is attached to the first surface 111 or the second surface 112.

[0093] In the above scheme, by setting the support plate 120 to be bonded to the first surface 111 and the second surface 112 of the base film 110, when the base film 110 surrounds and forms a space to accommodate the bare cell 200, the support plate 120 can also be correspondingly set with the side surface 210 of the bare cell 200 to protect the bare cell 200, thereby reducing the probability of the bare cell 200 being damaged by pressure from the base film 110.

[0094] In some embodiments, to improve the production efficiency of the heat-shrinkable film 100, step S10 may also provide a master film composed of multiple base films 110. That is, the master film can be divided into multiple base films 110 according to a predetermined size, and support plates 120 can be adhered to the first surface 111 and the second surface 112 of the master film corresponding to the multiple base films 110. At the same time, after the support plates 120 are adhered to the master film, the master film with support plates 120 can be rolled up for later use, so as to be cut into multiple base films 110 with support plates 120, that is, the heat-shrinkable film 100 is used to cover the bare battery cell 200.

[0095] In some embodiments, in addition to being bonded before the mother film is divided, the support plate 120 can also be bonded to multiple base films 110 after the mother film is divided into multiple base films 110, and finally packaged and other subsequent processes.

[0096] Furthermore, step S10 of providing the base film may include: S11, raw materials are mixed and then melt-extruded to obtain cast sheets.

[0097] S12, stretching the cast sheet in the first and second directions respectively.

[0098] S13 involves heat-setting and cooling the stretched cast sheet to obtain a base film.

[0099] As mentioned above, the raw materials of the base film 110 may include: 70-85% by weight of polyolefin resin, 10-20% by weight of inorganic ceramic particles, and 5-10% by weight of toughening agent. The polyolefin resin may include: high-density polyethylene (molecular weight 800,000-1,200,000) or linear low-density polyethylene; the inorganic ceramic particles may include: alumina and silicon dioxide, with a particle size of 300-800 nm; and the toughening agent may include: ethylene-vinyl acetate copolymer.

[0100] After the raw material feeding and proportioning of the base film 110 are completed, the raw materials of the base film 110 can be mixed, filtered, and fed into a twin-screw extruder. The extruded material is then melt-extruded through the twin-screw extruder to obtain a cast sheet of a predetermined thickness. The die of the twin-screw extruder can be a T-die, and the melt temperature of the twin-screw extruder can be controlled at 250-280℃, while the thickness of the extruded cast sheet can be controlled at 50-100μm.

[0101] After extruding to obtain a cast sheet of a predetermined thickness, the cast sheet can be preheated at a temperature controlled between 80-140℃. The preheated cast sheet is then introduced into a stretching mechanism, such as a roller assembly and a tenter frame, to stretch the cast sheet in the first direction X and the second direction Y. The stretching ratio of the cast sheet in the first direction X can be 2-3.5 times, and the stretching ratio in the second direction Y can be 1-1.5 times, allowing the heat shrinkage rate of the cast sheet in the first direction X to be controlled at 30-60%, and the heat shrinkage rate in the second direction Y to be controlled at 0-15%.

[0102] After stretching the cast sheet in the first direction X and the second direction Y, the cast sheet can be heat-set and cooled to eliminate the internal stress caused by stretching, finally obtaining the base film 110. The stretched cast sheet can be heat-set using a heating mechanism such as a hot-rolling wheel, with the heat-setting temperature controlled between 220-250℃ and the heat-setting time controlled between 30-60 seconds. Simultaneously, the heat-set cast sheet can be rapidly cooled using air cooling and / or liquid cooling to quickly cool the base film 110 to room temperature.

[0103] For example, when extruding cast sheets, the melt temperature of the twin-screw extruder can be controlled at 260°C, the extruder speed at 200 rpm, the temperature of the casting rolls at 25°C, and the thickness of the extruded cast sheet can be 50 μm. When preheating the extruded cast sheet, the preheating temperature can be 100°C, and the preheating time can be 40 seconds.

[0104] After the cast sheet is preheated, it can be stretched on one side in the first direction X by a roller assembly, with a stretching ratio of 3 times and a stretching temperature controlled at 110℃. Then, the cast sheet is stretched in the second direction Y by a tenter frame, with a stretching ratio of 2 times and a stretching temperature controlled at 100℃.

[0105] After the cast sheet is stretched, it can be heat-set at 230°C for 45 seconds. Once heat-set, the cast sheet can be rapidly cooled to room temperature using either air or liquid cooling, with a cooling rate controlled at 8°C / s.

[0106] Finally, after testing, the base film 110 prepared in the above manner showed a thermal shrinkage rate of 45% in the first direction X and 8% in the second direction Y. The test temperature was 80℃ and the test time was 10 seconds.

[0107] In the above scheme, by stretching the cast sheet in the first direction X and the second direction Y respectively, the cast sheet can have a predetermined shrinkage rate in the first direction X and the second direction Y to meet the requirements of the base film 110 for heat shrinkage. At the same time, by setting the heat shrinkage rate of the base film in the first direction X to 30-60% and the heat shrinkage rate in the second direction Y to 0-15%, the base film 110 can not only maintain a small heat shrinkage rate in the second direction Y to reduce the probability of wrinkles when shrinking in the second direction Y, but also maintain a large size in the first direction X to ensure that the base film 110 can form a sufficiently large space to accommodate the bare battery cell 200.

[0108] Please see Figure 6 , Figure 6 This is a schematic flowchart of a method for manufacturing a battery cell disclosed in an embodiment of this application, and the method for manufacturing the battery cell may include: S100 provides bare battery cells and the aforementioned heat-shrink film.

[0109] S200, the bare cell is placed in the space formed by the base film, and the bare cell is located between the support plates on the first surface and the second surface.

[0110] S300 preheats the placed base film and bare cell.

[0111] The S400 hot-presses the preheated base film and bare battery cell to shrink the base film to cover the bare battery cell and drive the support plate to adhere to the bare battery cell.

[0112] The S500 is used to cool and shape the hot-pressed base film and bare battery cell.

[0113] The bare cell 200 can be formed by alternating layers of positive electrode sheets, separators, and negative electrode sheets, with the alignment deviation between layers controlled within ±0.1mm. After the positive electrode sheets, separators, and negative electrode sheets are stacked, they can be vacuum-baked at a temperature of 80-120℃, a vacuum degree ≤-0.08MPa, and a baking time of 2-5 hours to remove moisture and solvents, thus obtaining the bare cell 200. The positive electrode sheet can be made of lithium-rich manganese ternary materials, such as lithium nickel cobalt manganese oxide, while the negative electrode material can be a graphite and silicon-carbon composite material. The separator can be a solid electrolyte membrane, and may include sulfide and oxide solid electrolytes.

[0114] In some embodiments, the specific configuration of the bare cell 200 may not be limited to the scheme shown in the above embodiments. The specific configuration of the bare cell 200 may also be selected according to design requirements. This embodiment will not list them one by one.

[0115] The heat-shrinkable film 100 can be prepared by the aforementioned heat-shrinkable film preparation method. The base film 110 of the heat-shrinkable film 100 can be arranged to form a space for placing the bare battery cell 200, and can be opened by a corresponding mechanical structure to maintain the space formed by the base film 110 for placing the bare battery cell 200. For example, the base film 110 can be connected end to end to form a space for placing the bare battery cell 200, and mechanical structures such as guide plates can be inserted into the base film 110 and can apply force to the two support plates 120 on the base film 110, so that the two support plates 120 move in opposite directions to support the entire base film 110, thereby reducing the probability of the bare battery cell 200 being misaligned and improving the production yield of the battery cell 10.

[0116] The bare battery cell 200 can be gripped by a gripper mechanism, which can hold the bare battery cell 200 on opposite sides in the first direction X to prevent the stacking of the bare battery cell 200 from shifting during gripping. Simultaneously, the gripper mechanism can place the bare battery cell 200 within the space enclosed by the base film 110, and then simultaneously remove the bare battery cell 200 and the base film 110 from the center using a pressure plate or block. This helps reduce the probability of stacking shifting of the bare battery cell 200 during transfer.

[0117] When the bare battery cell 200 is placed within the space enclosed by the base film 110, the bare battery cell 200 can be positioned between two support plates 120 on the base film 110, and the side surface 210 of the bare battery cell 200 can be disposed opposite to the two support plates 120. The unfolded base film 110 has a dimension in the first direction X that is at least 50% larger than the dimension of the bare battery cell 200 in the first direction X, and the unfolded base film 110 has a dimension in the second direction Y that is at least 30% larger than the dimension of the bare battery cell 200 in the second direction Y. Thus, the base film 110 can enclose a sufficiently large space to facilitate the placement of the bare battery cell 200 within the base film 110.

[0118] After being removed, the base film 110 and the bare cell 200 can be placed in the preheating zone for preheating. The preheating temperature can be 80-100℃ and the preset time can be 30-60 seconds. During the preheating process, the base film 110 can begin to shrink in the first direction X to initially adhere to the side surface 210 of the bare cell 200. The support plate 120 can also initially come into contact with the bare cell 200 under the action of the base film 110.

[0119] After the base film 110 and the bare cell 200 are preheated, they can be sent to a hot press for hot pressing. The hot pressing temperature can be 80-120℃, the hot pressing pressure can be 5-8MPa, and the hot pressing time can be 60-180 seconds. During the hot pressing process, the base film 110 can further shrink in the first direction X to tightly wrap the bare cell 200, and can also drive the support plate 120 to adhere to the bare cell 200. At the same time, the support plate 120 can support the base film 110 to reduce the pressure transmitted from the base film 110 to the edges of the bare cell 200, thereby reducing the probability of damage to the edges of the bare cell 200.

[0120] After the base film 110 and the bare cell 200 are hot-pressed, they can be cooled by air cooling or liquid cooling to cool the bare cell 200 covered with the base film 110 to room temperature, and the cooling rate can be 5-10℃ / s. During this process, the base film 110 and the support plate 120 can be shaped together.

[0121] In the above scheme, by providing a support plate 120 on the first surface 111 and the second surface 112 of the base film 110, the support plate 120 can support the pressure applied by the base film 110 to the bare cell 200 when the base film 110 and the bare cell 200 are hot-pressed, so as to reduce the probability of the bare cell 200 being damaged by pressure at the edge, thereby improving the production yield of the cell 10.

[0122] Furthermore, after coating the bare cell 200, the base film 110 can also shape the bare cell 200. This not only eliminates the need for adhesives to connect the separator to the positive and negative electrode plates, thus reducing the material cost of the bare cell 200, but also reduces the hot pressing time required to fix the base film 110 and the bare cell 200 by assisting in shaping the bare cell 200. This improves the hot pressing efficiency of the hot press and reduces the purchase cost of the hot pressing equipment.

[0123] It is understandable that when the thermal shrinkage rate of the base film 110 in the second direction Y is greater than 0%, the base film 110 will also shrink in the second direction Y during preheating and hot pressing.

[0124] Please refer to it again. Figure 2 This application embodiment also provides a battery cell 10, which is manufactured by the above-described battery cell manufacturing method and may include the aforementioned bare battery cell 200 and heat-shrinkable film 100. The bare battery cell 200 may have a side surface 210 parallel to the second direction Y, a base film 110 may be coated on the side surface 210, and support plates 120 on the first surface 111 and the second surface 112 may both contact the side surface 210.

[0125] In the above scheme, by setting the base film 110 to cover the side surface of the bare cell 200, and the support plate 120 to contact the side surface 210, the support plate 120 can protect the edge of the bare cell 200, thereby reducing the probability of the edge of the bare cell 200 being damaged by the pressure applied by the base film 110, thereby improving the reliability and service life of the cell 10.

[0126] Please see Figures 7 to 8 , Figure 7 This is a schematic diagram of the battery structure disclosed in the embodiments of this application. Figure 8 This is a schematic diagram of the structure of the electrical device disclosed in the embodiments of this application.

[0127] like Figure 7 As shown, this application also provides a battery 5, which may include at least one of the aforementioned battery cells 10. Of course, in addition to the battery cells 10, the battery 5 may also include a housing 51, which can accommodate at least one battery cell 10. When there are multiple battery cells 10, the multiple battery cells 10 can be electrically connected by at least one of the following methods: series connection, parallel connection, and mixed connection via a busbar. In the above solution, by including at least one high-yield battery cell 10 in the battery 5, the reliability and service life of the battery 5 are improved.

[0128] The housing 51 provides a storage space for the battery cell 10, and the housing 51 can adopt various structures. For example, the housing 51 may include a first part 511 and a second part 512, which overlap each other, forming a storage space together. Alternatively, the second part 512 may be a hollow structure with one end open, and the first part 511 may be a plate-like structure, covering the open side of the second part 512, so that the first part 511 and the second part 512 together form a storage space. Alternatively, the first part 511 and the second part 512 may both be hollow structures with one side open, with the open side of the first part 511 covering the open side of the second part 512, so that the first part 511 and the second part 512 together form a storage space.

[0129] like Figure 8 As shown, this application also provides an electrical device 1, which includes the aforementioned battery 5. The electrical device 1 may include, but is not limited to, mobile phones, tablets, laptops, electric toys, power tools, electric vehicles, automobiles, ships, or spacecraft. Taking an automobile as an example, the electrical device 1 can be a gasoline-powered vehicle, a natural gas-powered vehicle, or a new energy vehicle. New energy vehicles may be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles.

[0130] The electrical device 1 contains the aforementioned battery 5, which can be located at the bottom, head, or tail of the device. The battery 5 serves as the operating power source for the device. For example, the device may also include a controller 101 and a motor 102. The controller 101 controls the battery 5 to supply power to the motor 102, meeting the power requirements for starting, navigation, and driving. Furthermore, the battery 5 can not only serve as the operating power source for the device but also as its driving power source, replacing or partially replacing fuel oil or natural gas to provide driving power.

[0131] In the above solution, by including a highly reliable and long-life battery 5 in the power-consuming device 1, the reliability and lifespan of the power-consuming device 1 are also improved. It is understood that, in addition to power-consuming devices, the battery 5 provided in this application embodiment can also be used in energy storage devices such as energy storage cabinets.

[0132] Finally, in some specific application scenarios, to address the problem that existing heat shrink films easily damage bare battery cells, the heat shrink film 100 disclosed in this application embodiment may include: a base film 110 and a support plate 120. The base film 110 is configured to cover the bare battery cell 200 and has a first surface 111 and a second surface 112 that are disposed opposite to the bare battery cell 200 in a first direction X. The support plate 120 is provided on both the first surface 111 and the second surface 112. The first direction X is perpendicular to the second direction Y, and the second direction Y is the lead-out direction of the tab 201 of the bare battery cell 200.

[0133] The base film 110 has a heat shrinkage rate of 0-15% in the second direction Y and a heat shrinkage rate of 30-60% in the first direction X. The base film 110 comprises: 70-85% by weight of polyolefin resin, 10-20% by weight of inorganic ceramic particles, and 5-10% by weight of toughening agent. The polyolefin resin includes high-density polyethylene or linear low-density polyethylene. The inorganic ceramic particles include at least one of alumina and silicon dioxide. The toughening agent includes ethylene-vinyl acetate copolymer. The support plate 120 has a thickness of 0.1-1 mm in the first direction X and is located within the coverage area of ​​the orthogonal projection of the bare cell 200 in the first direction X. The support plate 120 is made of plastic and may include polycarbonate, polyamide, or polyphenylene sulfide.

[0134] The heat-shrinkable film 100 provided in this application embodiment has a base film 110 for covering the bare battery cell 200, which has a first surface 111 and a second surface 112 disposed opposite to the bare battery cell 200 in the first direction X. Both the first surface 111 and the second surface 112 are provided with support plates 120 in the first direction X. When the base film 110 covers the bare battery cell 200, the support plates 120 can support the base film 110 in the first direction X to limit the shrinkage of the base film 110 on the first surface 111 and the second surface 112, thereby reducing the pressure applied to the bare battery cell 200 when the base film 110 shrinks. This helps to reduce the probability of damage to the bare battery cell 200 during the covering process.

[0135] The above are merely embodiments of this application and do not limit the scope of this patent application. Any equivalent structural or procedural changes made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the scope of patent protection of this application.

Claims

1. A heat shrinkable film characterized by, The heat-shrinkable film comprises a base film and a support plate. The base film is configured to cover a bare battery cell and has a first surface and a second surface capable of being arranged opposite to the bare battery cell in a first direction; The first surface and the second surface are both provided with the support plate, the first direction is perpendicular to a second direction, and the second direction is a tab leading-out direction of the bare battery cell.

2. The heat shrinkable film of claim 1, wherein, The heat-shrinkage rate of the base film in the second direction is 0-15%.

3. The heat shrinkable film of claim 2, wherein, The heat-shrinkage rate of the base film in the first direction is 30-60%.

4. The heat shrinkable film of claim 1, wherein, The thickness of the support plate in the first direction is 0.1-1mm.

5. The heat shrinkable film of claim 1, wherein, The support plate is located within the coverage range of the bare battery cell in the first direction.

6. The heat shrinkable film of claim 1, wherein, The material of the support plate is plastic.

7. The heat shrinkable film of claim 1, wherein, The material of the support plate is polycarbonate, polyamide or polyphenylene sulfide.

8. The heat shrinkable film of claim 1, wherein, The base film comprises polyolefin resin with a mass fraction of 70-85%, inorganic ceramic particles with a mass fraction of 10-20% and toughening agent with a mass fraction of 5-10%.

9. The heat shrinkable film of claim 8, wherein, The polyolefin resin comprises high-density polyethylene or linear low-density polyethylene.

10. The heat shrinkable film of claim 8, wherein, The inorganic ceramic particles comprise at least one of aluminum oxide and silicon dioxide.

11. The heat shrinkable film of claim 8, wherein, The toughening agent comprises ethylene-vinyl acetate copolymer.

12. The heat shrinkable film of claim 1, wherein, The heat-shrinkage rate of the base film in the first direction is 50%, and the heat-shrinkage rate in the second direction is 10%.

13. A method for producing a heat-shrinkable film, for producing the heat-shrinkable film according to any one of claims 1 to 12, characterized by, The preparation method of the heat-shrinkable film comprises: providing the base film, and the base film has the first surface and the second surface; providing the support plate and bonding the support plate on the first surface and the second surface respectively.

14. The method of claim 13, wherein the heat shrinkable film is prepared by a method comprising: The step of providing the base film comprises: mixing raw materials and melt-extruding to obtain a cast sheet; stretching the cast sheet in the first direction and the second direction respectively; heat-setting and cooling the stretched cast sheet to obtain the base film.

15. The method of claim 14, wherein the heat shrinkable film is prepared by a process comprising: The shrinkage rate of the stretched cast sheet in the first direction is controlled to be 30-60%, and the shrinkage rate in the second direction is controlled to be 0-15%.

16. A method of making an electrical cell, the method comprising: The method for manufacturing the battery cell comprises: providing a bare battery cell and the heat-shrinkable film according to any one of claims 1-12; placing the bare battery cell into the space formed by the base film, and the bare battery cell is located between the support plates on the first surface and the second surface; preheating the placed base film and the bare battery cell; heat-pressing the preheated base film and the bare battery cell to make the base film shrink and cover the bare battery cell, and drive the support plates to be attached to the bare battery cell; cooling and setting the heat-pressed base film and the bare battery cell.

17. The method of claim 16, wherein: The size of the unfolded base film in the first direction is at least 50% larger than the size of the bare battery cell in the first direction; The size of the unfolded base film in the second direction is at least 30% larger than the size of the bare battery cell in the second direction.

18. An electric cell, characterized by The battery cell is manufactured by the method for manufacturing the battery cell according to any one of claims 16-17. The bare cell has a side surface parallel to the second direction, the base film is wrapped on the side surface, and the support plate on the first surface and the second surface are both in contact with the side surface.

19. A battery, characterized by The battery comprises at least one cell according to claim 18.

20. An electrical device, comprising: The power consuming device comprises the battery according to claim 19.

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