Aluminum plastic film and battery

Abstract

The utility model provides an aluminum plastic film and a battery. The aluminum plastic film comprises a base layer, a first heat sealing layer and a second heat sealing layer. In the thickness direction of the aluminum plastic film, one side of the base layer is coated with the first heat sealing layer, a containing groove is formed in the first heat sealing layer, and a groove opening of the containing groove faces the side away from the base layer; the second heat sealing layer comprises at least two heat sealing parts, the heat sealing parts are arranged at intervals and located in the containing groove, and the heat sealing parts are connected to the bottom wall of the containing groove in the thickness direction of the aluminum plastic film; wherein the melting point of each heat sealing part is lower than that of the first heat sealing layer, and each heat sealing part is used for bonding the battery cell main body. The battery comprises a battery cell main body and the aluminum plastic film, the battery cell main body is coated with the aluminum plastic film, and the second heat sealing layer is adhered to the battery cell main body, so that the battery cell main body is fixed. According to the aluminum-plastic film and the battery, the thickness uniformity of the battery can be improved, so that the volume energy density of a battery module is improved.

Description

Technical Field

[0001] This application relates to the field of battery technology, specifically to an aluminum-plastic film and a battery. Background Technology

[0002] In battery manufacturing, bare cells are thicker at the corresponding tab positions. Because the thicker parts of the bare cell adhere more tightly to the heat-sealing layer of the aluminum-plastic film, gaps easily form between the thicker areas and the heat-sealing layer. Therefore, during the battery hot-pressing process, the heat-sealing layer that is tightly bonded to the bare cell melts first. The surrounding, unmelted heat-sealing layer restricts the natural flow of the first-melted layer, resulting in inconsistent heat-sealing layer thickness after cooling, leading to poor battery thickness uniformity. When multiple batteries are assembled, this localized thickness difference creates assembly gaps between adjacent batteries, reducing the internal space utilization of the battery module and causing a loss in the volumetric energy density of the battery module. Utility Model Content

[0003] This application aims to address at least one of the technical problems existing in the prior art. To this end, this application proposes an aluminum-plastic film that can improve the thickness uniformity of the battery, thereby increasing the volumetric energy density of the battery module.

[0004] This application also proposes a battery having the aforementioned aluminum-plastic film.

[0005] The aluminum-plastic film according to the embodiments of this application includes a base layer, a first heat-sealing layer, and a second heat-sealing layer;

[0006] Along the thickness direction of the aluminum-plastic film, a first heat-sealing layer is coated on one side of the base layer. The first heat-sealing layer is provided with a receiving groove, and the opening of the receiving groove faces the side away from the base layer.

[0007] The second heat-sealing layer includes at least two heat-sealing parts, which are arranged at intervals from each other and are located in the receiving groove. Along the thickness direction of the aluminum-plastic film, each heat-sealing part is connected to the bottom wall of the receiving groove.

[0008] The melting point of each heat-sealing part is lower than that of the first heat-sealing layer, and each heat-sealing part is used to bond the battery cell body.

[0009] The aluminum-plastic film according to the embodiments of this application has at least the following beneficial effects: Since the heat-sealed part that can fit more tightly to the cell body is beneficial to heat conduction, while there are gaps between the surrounding heat-sealed parts and the cell body, the heat conduction efficiency is lower than that of the heat-sealed parts that fit more tightly. As a result, the heat-sealed parts that fit more tightly to the cell body will melt first, while the surrounding heat-sealed parts will melt later. The adjacent heat-sealed parts are arranged at intervals, and the intervals are used to allow the heat-sealed parts that melt first to flow to the surrounding areas, avoiding the accumulation of the heat-melted heat-sealed parts. As a result, the thickness of each heat-sealed part after cooling is more uniform, making the thickness of each position more uniform after the battery is formed. During the assembly of the battery module, space can be used more rationally, reducing space waste caused by uneven thickness and improving the volumetric energy density of the battery module.

[0010] According to some embodiments of this application, along the thickness direction of the aluminum-plastic film, the cross-sectional area of ​​the heat-sealed portion on the side away from the base layer is smaller than the cross-sectional area on the side closer to the base layer.

[0011] According to some embodiments of this application, the cross-sectional area of ​​the heat-sealed portion gradually decreases from the side furthest from the substrate to the side closest to the substrate.

[0012] According to some embodiments of this application, the cross-sectional area of ​​the heat-sealed portion is equal at all points along the thickness direction of the aluminum-plastic film.

[0013] According to some embodiments of this application, along the thickness direction of the aluminum-plastic film, the thickness of each heat-sealed portion is less than the depth of the receiving groove.

[0014] According to some embodiments of this application, from the outer periphery of the second heat-sealing layer near the first heat-sealing layer to the center of the second heat-sealing layer, the second heat-sealing layer is arranged in an arc-shaped concave shape, the thickness of the battery cell body is T, and the curvature of the arc is [missing information]. to .

[0015] According to some embodiments of this application, the melting point of the first heat-sealing layer is 130°C to 150°C, the melting point of the heat-sealing portion is 40°C to 60°C, and the melting point difference between the first heat-sealing layer and the heat-sealing portion is 70°C to 110°C.

[0016] According to some embodiments of this application, the thickness of the heat-sealed portion is 5 μm to 20 μm, the thickness ratio of the heat-sealed portion to the first heat-sealing layer is 11% to 50%, and the thickness of the heat-sealed portion is 3.8% to 20% of the thickness of the aluminum-plastic film.

[0017] The battery according to the embodiments of this application includes a cell body and an aluminum-plastic film in any of the above embodiments, wherein the aluminum-plastic film covers the cell body and each heat-sealed part is bonded to the cell body.

[0018] The battery according to the embodiments of this application has at least the following beneficial effects: at least a portion of the cell body is bonded to each heat-sealing part, thus eliminating the need to provide hot melt adhesive between the cell body and the aluminum-plastic film. On the one hand, this is beneficial to reduce the volume of the battery and improve the volumetric energy density of the battery. On the other hand, the coverage area of ​​the second heat-sealing layer can be the thicker area of ​​the cell body. Direct bonding of the thicker area of ​​the cell body to the aluminum-plastic film is beneficial to balance the thickness of the battery and make the surface thickness of the battery more uniform.

[0019] According to some embodiments of this application, the aluminum-plastic film includes a covering portion and a sealing portion. The outer periphery of the covering portion is connected to the sealing portion. The covering portion is provided with a receiving cavity, and the battery cell body is located in the receiving cavity. The covering portion includes a second heat-sealing layer.

[0020] According to some embodiments of this application, the sum of the areas of the second heat-sealing layer distribution area is a, the sum of the outer perimeters of the second heat-sealing layer distribution area is c, the weight of the battery cell body is b, and b / c≥4.2mm / g;

[0021] Specifically, when the capacity of the main cell is 4Ah, a / c ≥ 24.2mm². 2 / g;

[0022] When the capacity of the main cell is 5Ah to 6Ah, a / c ≥ 26.3mm 2 / g;

[0023] When the capacity of the main cell is greater than 6Ah, a / c ≥ 28.3mm 2 / g.

[0024] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0025] The present application will be further described below with reference to the accompanying drawings and embodiments, wherein:

[0026] Figure 1 This is a partial structural diagram of the aluminum-plastic film according to an embodiment of this application;

[0027] Figure 2 This is a partial structural diagram of the aluminum-plastic film according to another embodiment of this application;

[0028] Figure 3 This is a schematic diagram showing the unfolded aluminum-plastic film of this application;

[0029] Figure 4 This is a schematic diagram of the structure of the battery cell body and part of the aluminum-plastic film in an embodiment of this application;

[0030] Figure 5 This is a top view of the battery in an embodiment of this application.

[0031] Reference numerals: Base layer 100, Nylon layer 110, Aluminum layer 120;

[0032] First heat-sealing layer 210, receiving groove 211, second heat-sealing layer 220, heat-sealing part 221, covering part 230, and sealing part 240;

[0033] The main body of the battery cell is 310, the straight structure is 311, and the corner structure is 312. Detailed Implementation

[0034] The embodiments of this application are described in detail below. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0035] In the description of this application, it should be understood that the orientation descriptions, such as up, down, front, back, left, right, etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0036] In the description of this application, "several" means one or more, "multiple" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0037] In the description of this application, unless otherwise expressly defined, terms such as "setup," "installation," and "connection" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this application in conjunction with the specific content of the technical solution.

[0038] In the description of this application, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0039] The embodiments of this application are described below with reference to the accompanying drawings:

[0040] refer to Figures 1 to 4 According to an embodiment of this application, the aluminum-plastic film includes a base layer 100, a first heat-sealing layer 210, and a second heat-sealing layer 220. Along the thickness direction of the aluminum-plastic film, the first heat-sealing layer 210 is coated on one side of the base layer 100. The first heat-sealing layer 210 is provided with a receiving groove 211, the opening of which faces away from the base layer 100. The second heat-sealing layer 220 includes at least two heat-sealing portions 221, which are spaced apart from each other and located within the receiving groove 211. Along the thickness direction of the aluminum-plastic film, each heat-sealing portion 221 is connected to the bottom wall of the receiving groove 211. The melting point of each heat-sealing portion 221 is lower than that of the first heat-sealing layer 210. Each heat-sealing portion 221 is used to bond the battery cell body 310. The shape of the heat-sealing portion 221 can be a cuboid, a cube, or the like. Along the length and / or width direction of the aluminum-plastic film, adjacent heat-sealing portions 221 are spaced apart.

[0041] Based on this, by controlling the hot-pressing temperature during the hot-pressing process, each heat-sealing part 221 can be melted and connected to the cell body 310. Since there are gaps between each heat-sealing part 221, the melted parts can flow freely in all directions, effectively avoiding mutual interference when adjacent heat-sealing parts 221 melt. Therefore, after the second heat-sealing layer 220 cools, it not only secures the cell body 310 to the aluminum-plastic film, ensuring the battery's drop resistance, but also makes the melted second heat-sealing layer 220 smoother, which is beneficial for improving the volumetric energy density of the battery module.

[0042] refer to Figures 1 to 4For example, the second heat-sealing layer 220 can correspond to the thicker part of the cell body 310. The second heat-sealing layer 220 is directly connected to and fixed to the cell body 310 during the hot pressing process, without the need to apply adhesive to the thicker part of the cell body 310. On the one hand, this avoids the extra thickness caused by applying adhesive to the cell body 310. On the other hand, eliminating the adhesive application step can simplify the battery production process and reduce the use of hot melt adhesive materials. Because the thickness of the cell body 310 is uneven, the heat-sealed portion 221 that is more tightly attached to the cell body 310 is beneficial for heat conduction, while the heat-sealed portions 221 around the cell body 310 are prone to gaps, making the heat conduction efficiency lower than that of the tightly attached heat-sealed portions 221. As a result, the heat-sealed portions 221 that are more tightly attached to the cell body 310 will melt first, while the heat-sealed portions 221 around the cell body will melt later. Based on this, the adjacent heat-sealed portions 221 in this application are arranged at intervals. The intervals are used to allow the heat-sealed portions 221 that melt first to flow to the surrounding areas, avoiding the accumulation of the melted heat-sealed portions 221. As a result, the thickness of each heat-sealed portion 221 after cooling is more uniform, making the thickness of each position more uniform after the battery is formed. During battery module assembly, space can be used more rationally, reducing space waste caused by uneven thickness and improving the volumetric energy density of the battery module.

[0043] It should be noted that the anode sheet, separator, and cathode sheet are wound in an alternating stacking manner to form the cell body 310. Both the anode sheet and the cathode sheet are welded with tabs. The welding position of the tabs and the electrode sheets will result in a thickness overlap, which makes the thickness of the cell body 310 at the tab welding position 10μm to 20μm greater than other areas. The cell body 310 has local bulges. If hot melt adhesive is attached to the cell body 310 for fixation, the thickness of the hot melt adhesive will further aggravate the thickness bulge in this area, resulting in uneven thickness of the battery as a whole.

[0044] refer to Figures 1 to 4 In this application, the positions of each heat-sealing part 221 correspond to the thicker areas at the electrode tab welding points of the cell body 310. Due to the presence of thickness protrusions, the tightness of the fit between each heat-sealing part 221 and the cell body 310 varies. The heat-sealing part 221 corresponding to the maximum thickness of the cell body 310 has the tightest fit with the cell body 310. During the hot pressing process, each heat-sealing part 221, due to its lower melting point than the first heat-sealing layer 210, can melt while the first heat-sealing layer 210 is in a solid state and directly adhere to the surface of the thicker area of ​​the cell body 310, thus eliminating the need for hot melt adhesive and avoiding the thickness accumulation problem caused by adhesive application. Furthermore, there are gaps between each heat-sealing part 221, which are used to avoid interfering with the sequential melting flow of each heat-sealing part 221, thereby improving the thickness consistency of each part after battery molding.

[0045] refer to Figures 1 to 4In other embodiments, the base layer 100 includes a nylon layer 110 and an aluminum layer 120 stacked along the thickness direction of the aluminum-plastic film. The first heat-sealing layer 210 is connected to the aluminum layer 120. The nylon layer 110 is located on the side of the aluminum layer 120 away from the first heat-sealing layer 210. The nylon layer 110 has good wear resistance and puncture resistance, providing basic protection for the battery cell body 310. The aluminum layer 120 is mainly used to isolate water vapor, light and oxygen. The first heat-sealing layer 210 can be made of polypropylene. Each heat-sealing part 221 can be made of a substance with a melting point lower than that of the first heat-sealing layer 210. Specifically, it can be modified polypropylene (blended with ultra-low melting point polymers, such as ethylene-vinyl acetate copolymer) or coated on its surface with an adhesive with a melting point lower than that of the first heat-sealing layer 210 (EVA, polyurethane PU, pressure-sensitive adhesive (PSA) etc.). It is fixedly connected to the bottom wall of the receiving groove 211 along the thickness direction.

[0046] Each heat-sealing part 221 is located in the receiving groove 211 to prevent each heat-sealing part 221 from protruding outward relative to the side of the first heat-sealing layer 210 away from the base layer 100. Thus, when each heat-sealing part 221 melts and bonds to the thicker area of ​​the cell body 310 in the hot pressing process, it can offset the local thickness difference of the cell body 310 without the need for adhesive, making the overall thickness distribution of the battery more uniform.

[0047] It should be noted that in this embodiment, the first heat-sealing layer 210 is provided with a receiving groove 211, which includes a bottom wall and a side wall. The bottom wall can be parallel to the base layer 100. The second heat-sealing layer 220 is connected to the bottom wall of the receiving groove 211, that is, each heat-sealing part 221 is connected to the first heat-sealing layer 210. The first heat-sealing layer 210 is used to isolate the electrolyte and the contact aluminum layer 120 of the battery cell body 310.

[0048] refer to Figures 1 to 4 In other embodiments, the receiving groove 211 is a through groove that penetrates the first heat-sealing layer 210 along the thickness direction of the aluminum-plastic film. The first heat-sealing layer 210 is connected to the base layer 100. The base layer 100 blocks one side of the receiving groove 211, so that the opening of the receiving groove 211 faces away from the base layer 100. In this case, the base layer 100 serves as the bottom wall of the receiving groove 211, and each heat-sealing part 221 is located inside the receiving groove 211 and connected to the base layer 100. Thus, while keeping the thickness of the first heat-sealing layer 210 unchanged, compared to a non-through groove structure, the through groove design allows each heat-sealing part 221 to extend upward from the surface of the base layer 100 to the opening position, forming thicker heat-sealing parts 221. The connection between the cell body 310 and the aluminum-plastic film is more robust, effectively improving the structural stability of the battery during long-term use.

[0049] It should be noted that each heat-sealing part 221 is connected to the base layer 100, so that heat can be directly transferred to the second heat-sealing layer 220 through the base layer 100 during the hot pressing process, so as to melt each heat-sealing part 221 more quickly, which is beneficial to improving the production efficiency of the battery.

[0050] refer to Figures 1 to 4 In some embodiments, along the thickness direction of the aluminum-plastic film, the cross-sectional area of ​​the heat-sealing portion 221 on the side away from the base layer 100 is smaller than the cross-sectional area on the side closer to the base layer 100. That is, when each heat-sealing portion 221 is transversely cut along a plane perpendicular to the thickness direction of the aluminum-plastic film, the cross-sectional area of ​​the side of the heat-sealing portion 221 used to adhere to the battery cell body 310 is smaller, making the melting of each part of the heat-sealing portion 221 more uniform, further improving the flatness of the second heat-sealing layer 220 after cooling, thereby making the battery flatter.

[0051] Specifically, each heat-sealing part 221 is transversely cut at various points along a plane parallel to the thickness direction of the aluminum-plastic film. The cross-sectional shape of the heat-sealing part 221 can be a cone, a semi-ellipse, or a combination of a rectangle and a semi-circle, etc., to ensure that the cross-sectional area of ​​each heat-sealing part 221 on the side away from the base layer 100 is smaller. In the hot-pressing process, heat is transferred from the base layer 100 to the heat-sealing part 221, so that the side of the heat-sealing part 221 closer to the base layer 100 receives heat first, and the side farther away from the base layer 100 receives heat later. Since the part with a smaller cross-sectional area is easier to melt, setting the side of the heat-sealing part 221 away from the base layer 100 to have a smaller cross-sectional area can balance the melting time of each part of the heat-sealing part 221, making the melting of each part of the heat-sealing part 221 more uniform. This can avoid the unmelted part of the heat-sealing part 221 restricting the molten part, which is beneficial to ensuring the flatness of the second heat-sealing layer 220 after cooling. In addition, it is also beneficial to reduce the problem of thermal stress concentration caused by the difference in melting rate of different parts during the heat-sealing process, further improving the structural stability and sealing reliability of the heat-sealing area, and ensuring the overall quality of battery packaging.

[0052] refer to Figures 1 to 4 In some embodiments, the cross-sectional area of ​​the heat-sealing portion 221 gradually decreases from the side away from the base layer 100 to the side closer to the base layer 100. That is, from the tail (closer to the base layer 100) to the head (away from the base layer 100) of the heat-sealing portion 221, the cross-sectional area of ​​the heat-sealing portion 221 gradually decreases. For example, the heat-sealing portion 221 can be transversely cut along a plane parallel to the thickness of the aluminum-plastic film. The cross-section of the heat-sealing portion 221 can be a shape with gradual transition characteristics, such as a semi-ellipse, a cone, or a trapezoid. The semi-ellipse is formed by cutting an ellipse in half along the minor axis, making the semi-major axis parallel to the thickness direction of the aluminum-plastic film, thereby forming a gradual cross-sectional structure. The outer surface of the heat-sealing portion 221 adopts a smooth transition design from the tail to the head, which can further optimize the heat transfer on the heat-sealing portion 221.

[0053] In the hot-pressing process, heat is transferred from the base layer 100 to the heat-sealing part 221, passing sequentially through the tail and head of the heat-sealing part 221. Since the heat is transferred to the tail of the heat-sealing part 221 first, the tail of the heat-sealing part 221 tends to melt first. Therefore, the tail near the base layer 100 is set with a larger cross-sectional area to slow down the melting speed, while the head of the heat-sealing part 221 is set with a smaller cross-sectional area, making it easier for the head of the heat-sealing part 221 to heat up and melt quickly. This balances the melting time at different positions of the heat-sealing part 221. Moreover, since the cross-sectional area of ​​the heat-sealing part 221 gradually changes from the tail to the head, the melting process of the tail and the head of the heat-sealing part 221 becomes more synchronized. This avoids the restriction of the melted area by the unmelted area, which is beneficial to further improve the flatness of the second heat-sealing layer 220, improve the bonding uniformity of the heat-sealing interface, and thus enhance the overall structural stability of the battery after encapsulation.

[0054] refer to Figures 1 to 4 In some embodiments, the cross-sectional area of ​​the heat-sealing portion 221 is equal at all points along the thickness direction of the aluminum-plastic film. For example, the heat-sealing portion 221 can be in the shape of a cylinder or prism, which facilitates the forming of the heat-sealing portion 221 and makes the shapes of each heat-sealing portion 221 more similar.

[0055] refer to Figures 1 to 4 In some embodiments, along the thickness direction of the aluminum-plastic film, the thickness of each heat-sealing part 221 is less than the depth of the receiving groove 211, so that the receiving groove 211 forms a space that can accommodate part of the battery cell body 310. For example, when the thicker part of the battery cell body 310 is attached to the aluminum-plastic film, the thicker part can be embedded in the reserved space of the receiving groove 211 and bonded to each heat-sealing part 221 in the receiving groove 211. Thus, the space of the receiving groove 211 can accommodate the local protrusion of the battery cell body 310 to reduce the overall thickness of the battery, and can also achieve the fixed connection between the battery cell and the aluminum-plastic film through the bonding effect of the second heat-sealing layer 220. Moreover, the space of the receiving groove 211 is larger than the sum of the volumes of each heat-sealing part 221, which also facilitates the melting and flow of each heat-sealing part 221. When the battery is subjected to mechanical stress such as drop, the cell body 310 is embedded in the receiving groove 211 and is bonded by each heat-sealing part 221, which can more effectively limit its displacement relative to the aluminum-plastic film, thereby preventing the burrs of the cell body 310 from puncturing the first heat-sealing layer 210 due to movement, and also reducing the risk of the cell body 310 moving and pulling the tabs to deform or the weld joints to break.

[0056] refer to Figures 1 to 4 In some embodiments, from the outer periphery of the second heat-sealing layer 220 near the first heat-sealing layer 210 to the center of the second heat-sealing layer 220, the second heat-sealing layer 220 is arranged in an arc-shaped concave shape, that is, each heat-sealing part 221 fits together to form an arc-shaped concave shape, the thickness of the battery cell body 310 is T, and the curvature of the arc is [missing information]. to The surface of the cell body 310 has a local arc-shaped protrusion. Therefore, setting the second heat-sealing layer as an arc-shaped concave structure facilitates the adhesion between the second heat-sealing layer 220 and the cell body 310, making the adhesion between the two more solid. Moreover, the arc-shaped concave structure can accommodate the local protrusion of the cell body 310, which is beneficial to further improve the flatness of the battery.

[0057] Among them, the second heat-sealing layer 220 is recessed on the side facing the base layer 100. T is a mathematical constant, and its value varies depending on the size of the battery cell body 310 covered by aluminum-plastic film.

[0058] refer to Figures 1 to 4 In some embodiments, the melting point of the first heat-sealing layer 210 is 130°C to 150°C, and the melting point of each heat-sealing part 221 is 40°C to 60°C. The difference between the melting points of the first heat-sealing layer 210 and the heat-sealing part 221 is 70°C to 110°C, which limits the lower limit of the melting point of each heat-sealing part 221 to ensure that each heat-sealing part 221 is in a solid state at room temperature, so as to maintain a stable bond to the cell body 310 during daily use of the battery and ensure the mechanical properties of the battery such as drop resistance. By limiting the upper limit of the melting point of each heat-sealing part 221, the heat-sealing part 221 can be melted at a lower temperature to reduce energy consumption and production costs, while avoiding the melting of the first heat-sealing layer 210 due to excessive temperature. This maintains the effective isolation of the first heat-sealing layer 210 from the cell body 310 and the base layer 100. The first heat-sealing layer 210 remains solid, which not only plays the role of a physical barrier, but also resists the burrs that may exist in the cell body 310 with its own structural strength, preventing the base layer 100 from being punctured or damaged.

[0059] Specifically, the melting point of each heat-sealing part 221 can be 40℃, 45℃, 50℃, 55℃ or 60℃, or it can be a range of any two temperature values ​​among 40℃, 45℃, 50℃, 55℃ or 60℃ as endpoints. Depending on the operating temperature of the battery, adhesives with different melting points can be flexibly used. Similarly, the melting point of the first heat-sealing layer 210 can be 130℃, 135℃, 140℃, 145℃ or 150℃, or it can be a range of any two temperature values ​​among 130℃, 135℃, 140℃, 145℃ and 150℃ as endpoints.

[0060] refer to Figures 1 to 4In some embodiments, the thickness of each heat-sealing portion 221 is 5 μm to 20 μm, the thickness ratio of the heat-sealing portion 221 to the first heat-sealing layer 210 is 11% to 50%, and the thickness of the heat-sealing portion 221 is 3.8% to 20% of the thickness of the aluminum-plastic film. For example, the thickness of the first heat-sealing layer 210 is greater than the thickness of the second heat-sealing layer 220, and the thickness of the first heat-sealing layer 210 is 30 μm to 45 μm. This limits the lower limit of the thickness of each heat-sealing portion 221 to ensure that each heat-sealing portion 221 has sufficient material to reliably bond with the cell body 310 without the need for hot melt adhesive, preventing the cell body 310 from moving relative to the aluminum-plastic film due to insufficient bonding strength after the battery is dropped. Limiting the upper limit of the thickness of each heat-sealing portion 221, on the one hand, allows for thinner heat-sealing portions 221... 1. During hot pressing, the material can melt more quickly and synchronously, making the material flow more smoothly. The surface of the adhesive layer formed after cooling is smoother. At the same time, it reduces the problem of prolonged cooling time caused by excessive thickness, thus improving production efficiency. On the other hand, it ensures that after each heat-sealing part 221 flows and fills the receiving groove 211, the bottom of each heat-sealing part 221 is still supported by the first heat-sealing layer 210 as a barrier, effectively isolating the battery cell body 310 or electrolyte from direct contact with the base layer 100 (such as the aluminum layer 120), thus avoiding the risk of corrosion or short circuit.

[0061] Specifically, the thickness of each heat-sealing portion 221 can be 5μm, 10μm, 15μm, or 20μm, or it can be an interval value with any two thickness values ​​among 5μm, 10μm, 15μm, or 20μm as endpoints. The thickness of each heat-sealing portion 221 can be adjusted according to the thickness of the aluminum-plastic film. The thickness ratio of the heat-sealing portion 221 to the first heat-sealing layer 210 can be 11%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, or 50%, and the thickness of the heat-sealing portion 221 can be 3.8%, 5%, 10%, 15%, or 20% of the thickness of the aluminum-plastic film. The thickness of the aluminum-plastic film can be from 70μm to 130μm, the thickness of the first heat-sealing layer 210 can be from 30μm to 40μm, and the thickness of the heat-sealing part 221 can be adjusted according to the thickness of the aluminum-plastic film and the thickness of the first heat-sealing layer 210, so as to control the thickness of the heat-sealing part 221 within the above ratio, so as to balance the structural strength of the aluminum-plastic film and the encapsulation requirements of the battery.

[0062] refer to Figures 1 to 4The battery according to the embodiments of this application includes a cell body 310 and an aluminum-plastic film as described in any of the above embodiments. The aluminum-plastic film covers the cell body 310, and each heat-sealing part 221 is bonded to the cell body 310. In the bonding area, each heat-sealing part 221 achieves a firm connection between the cell body 310 and the aluminum-plastic film by melting and then cooling and solidifying. This ensures the structural stability of the battery under drop conditions and eliminates the need for hot melt adhesive used for fixing in traditional processes. It avoids the need for additional material thickness accumulation, allowing the cell body 310 to occupy a larger proportion of the space inside the battery, thereby improving the volumetric energy density of the battery.

[0063] Specifically, along the thickness direction of the battery, the projection of the second heat-sealing layer 220 covers the tab welding area of ​​the cell body 310. Within the tab welding area, the thickness is typically greater than in other areas due to the thickness overlap caused by the tab welding. Each heat-sealing part 221 fills into the receiving groove 211 and adheres to the surface of the cell body 310, not only offsetting the thickness protrusion at the tab welding point and making the overall battery thickness distribution more uniform, but also freeing up more internal volume for the cell body 310 by eliminating the need for hot melt adhesive. This also reduces the structural gap between adjacent cells caused by localized thickness unevenness, which is beneficial for improving the stacking tightness of the battery module.

[0064] refer to Figures 1 to 5 In some embodiments, the aluminum-plastic film includes a covering portion 230 and a sealing portion 240. The outer periphery of the covering portion 230 is connected to the sealing portion 240. The covering portion 230 has a receiving cavity, and the battery cell body 310 is located within the receiving cavity. The covering portion 230 includes a second heat-sealing layer 220. Defining the distribution range of the second heat-sealing layer 220 can ensure the stability of the seal at the edge of the aluminum-plastic film. It should be understood that the sealing portion 240 relies on the first heat-sealing layer 210 for adhesion and sealing. The melting point of the first heat-sealing layer 210 is higher than that of the second heat-sealing layer 220, and it can remain solid during the hot pressing process and the high-temperature operating environment of the battery, avoiding sealing failure due to melting. Thus, it not only ensures the fixation of the battery cell body 310 in the receiving cavity, but also avoids the risk of gaps or leakage in the sealing portion 240 due to material melting, which is beneficial to extending the battery's service life.

[0065] Specifically, the second heat-sealing layer 220 is only distributed within the covering portion 230 to avoid the second heat-sealing layer 220 extending to the sealing portion 240 and causing sealing failure. For example, along the thickness direction of the battery, the projection of the second heat-sealing layer 220 on the cell body 310 covers the flat structure 311. The projection of the second heat-sealing layer 220 on the cell body 310 can be flush with the edge of the flat structure 311. The second heat-sealing layer 220 can be bonded to the cell body 310 by heat fusion to achieve the fixation of the cell body 310 and the sealing of the battery. In addition, compared to the edge of the flat structure 311 extending beyond the projection edge of the second heat-sealing layer 220, it is also beneficial to ensure the flatness of the battery corresponding to the flat structure 311 and avoid local protrusions in the battery corresponding to the flat structure 311.

[0066] refer to Figures 1 to 4 In other embodiments, the cell body 310 includes a flat structure 311. Along the thickness direction of the battery, the second heat-sealing layer 220 covers at least one side of the flat structure 311 to ensure the fixation of the cell body 310. Specifically, the anode sheet, separator, and cathode sheet are wound to form the cell body 310. Each layer of material includes flat sections and corner sections. The flat sections together constitute the flat structure 311 of the cell body 310, and the corner sections form corner structures 312 located on both sides. Along the width direction of the battery, the flat structure 311 is connected to the two corner structures 312. Along the thickness direction of the battery, the two opposite sides of the flat structure 311 are the main stress surfaces. The second heat-sealing layer 220 covers at least one side and is fixed by melting and bonding to the surface of the flat structure 311.

[0067] It should be noted that when the aluminum-plastic film covers the main body of the battery cell 310, its thickness direction needs to be distinguished in conjunction with the battery shape: when not covered, the aluminum-plastic film has a flat structure and the thickness direction is consistent; after covering, the area on both sides of the flat structure 311 of the battery cell maintains a planar shape and the thickness direction is consistent with the thickness direction of the battery, while the area covering the corner structure 312 forms a curved surface and the thickness direction changes accordingly.

[0068] Based on this, firstly, the first heat-sealing layer 210 can be provided with a single receiving groove 211 spanning both sides of the flat structure 311, so that the second heat-sealing layer 220 covers its opposite sides. Secondly, the first heat-sealing layer 210 is provided with two spaced receiving grooves 211, and the second heat-sealing layer 220 in each receiving groove 211 corresponds to both sides of the flat structure 311. By fixing the flat structure 311 on both sides, the connection stability between the battery cell body 310 and the aluminum-plastic film can be enhanced.

[0069] refer to Figures 1 to 4In other embodiments, at least one side of the flat structure 311 is located in the receiving groove 211 along the thickness direction of the battery. For example, when the first heat-sealing layer 210 has two receiving grooves 211, the height of the second heat-sealing layer 220 inside the groove is lower than the groove opening, so that the receiving groove 211 retains space to accommodate part of the flat structure 311. When the aluminum-plastic film covers the battery cell body 310, the upper and lower sides of the flat structure 311 are respectively embedded in the upper and lower receiving grooves 211, and the surface of the flat structure 311 is directly bonded to the second heat-sealing layer 220 in the corresponding receiving groove 211. By incorporating both sides of the flat structure 311 into the space of the receiving groove 211, and using the hot melt bonding characteristics of the second heat-sealing layer 220 to replace the traditional hot melt adhesive, the fixed connection between the battery cell body 310 and the aluminum-plastic film is achieved simultaneously on both the upper and lower sides. On the one hand, this is beneficial to improving the volumetric energy density of the battery; on the other hand, by bonding the flat structure 311 on both sides, the drop resistance of the battery is further guaranteed.

[0070] refer to Figures 1 to 4 In some embodiments, the sum of the areas of the distribution regions of the second heat-sealing layer 220 is 'a', the sum of the outer perimeters of the distribution regions of the second heat-sealing layer 220 is 'b', and the weight of the cell body 310 is 'c', where b / c ≥ 4.2 mm / g; wherein, when the capacity of the cell body 310 is 4 Ah, a / c ≥ 24.2 mm / g. 2 / g; When the capacity of the main cell 310 is 5Ah to 6Ah, a / c ≥ 26.3mm 2 / g; When the capacity of the main cell 310 is greater than 6Ah, a / c ≥ 28.3mm 2 / g, thus, as the capacity of the battery cell body 310 increases, the ratio of the sum of the areas of the distribution region of the second heat-sealing layer 220 to the weight of the battery cell body 310 increases. By limiting the lower limit of the ratio of the area of ​​the second heat-sealing layer 220 to the weight of the battery cell body 310, it is ensured that the effective bonding area per unit weight of battery cell is sufficient to resist external mechanical stress. Furthermore, limiting the lower limit of the ratio of the outer perimeter of the second heat-sealing layer 220 to the weight of the battery cell body 310 also ensures the bonding strength between the second heat-sealing layer 220 and the battery cell body 310. At least one of these ratio limits ensures a stable connection between the second heat-sealing layer 220 and the battery cell body 310.

[0071] It should be noted that there are physical upper limits to the values ​​of a and b. The maximum theoretical value of a does not exceed the area of ​​the outer surface of the cell body 310. The upper limit of b is determined by the geometric shape of the second heat-sealing layer 220. The more curved the outer edge of the second heat-sealing layer 220 is, the larger the value of b is. The value of b is limited by the maximum outline length of the outer surface of the cell.

[0072] The embodiments of this application have been described in detail above with reference to the accompanying drawings. However, this application is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of this application. Furthermore, unless otherwise specified, the embodiments and features described in the embodiments of this application can be combined with each other.

Claims

1. An aluminum-plastic film, characterized in that, include: grassroots level; The first heat-sealing layer is coated on one side of the base layer along the thickness direction of the aluminum-plastic film. The first heat-sealing layer is provided with a receiving groove, and the opening of the receiving groove faces the side away from the base layer. The second heat-sealing layer includes at least two heat-sealing portions, each heat-sealing portion being arranged at a distance from each other and located within the receiving groove. Along the thickness direction of the aluminum-plastic film, each heat-sealing portion is connected to the bottom wall of the receiving groove. The melting point of each heat-sealing part is lower than that of the first heat-sealing layer, and each heat-sealing part is used to bond the battery cell body.

2. The aluminum-plastic film according to claim 1, characterized in that, Along the thickness direction of the aluminum-plastic film, the cross-sectional area of ​​the heat-sealed portion on the side away from the base layer is smaller than the cross-sectional area on the side closer to the base layer.

3. The aluminum-plastic film according to claim 2, characterized in that, The cross-sectional area of ​​the heat-sealed portion gradually decreases from the side furthest from the base layer to the side closest to the base layer.

4. The aluminum-plastic film according to claim 1, characterized in that, Along the thickness direction of the aluminum-plastic film, the cross-sectional area of ​​the heat-sealed portion is equal at all points.

5. The aluminum-plastic film according to claim 1, characterized in that, Along the thickness direction of the aluminum-plastic film, the thickness of each heat-sealed portion is less than the depth of the receiving groove.

6. The aluminum-plastic film according to claim 1, characterized in that, From the outer periphery of the second heat-sealing layer near the first heat-sealing layer to the center of the second heat-sealing layer, the second heat-sealing layer is arranged in an arc-shaped concave shape. The thickness of the battery cell body is T, and the curvature of the arc is [missing information]. to .

7. The aluminum-plastic film according to claim 1, characterized in that, The first heat-sealing layer has a melting point of 130°C to 150°C, the heat-sealing part has a melting point of 40°C to 60°C, and the difference between the melting points of the first heat-sealing layer and the heat-sealing part is 70°C to 110°C.

8. The aluminum-plastic film according to claim 1, characterized in that, The thickness of the heat-sealed portion is 5 μm to 20 μm, the thickness ratio of the heat-sealed portion to the first heat-sealed layer is 11% to 50%, and the thickness of the heat-sealed portion is 3.8% to 20% of the thickness of the aluminum-plastic film.

9. A battery, characterized in that, include: Battery cell body; The aluminum-plastic film according to any one of claims 1 to 8, wherein the aluminum-plastic film covers the battery cell body, and each of the heat-sealed portions is bonded to the battery cell body.

10. The battery according to claim 9, characterized in that, The aluminum-plastic film includes a covering part and a sealing part. The outer periphery of the covering part is connected to the sealing part. The covering part has a receiving cavity, and the battery cell body is located in the receiving cavity. The covering part includes a second heat-sealing layer.

11. The battery according to claim 9, characterized in that, The sum of the areas of the second heat-sealing layer distribution area is a, the sum of the outer perimeters of the second heat-sealing layer distribution area is c, the weight of the battery cell body is b, and b / c≥4.2mm / g; Specifically, when the capacity of the main body of the battery cell is 4Ah, a / c ≥ 24.2mm. 2 / g; When the capacity of the main body of the battery cell is 5Ah to 6Ah, a / c ≥ 26.3mm 2 / g; When the capacity of the main body of the battery cell is greater than 6Ah, a / c ≥ 28.3mm 2 / g.

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