A top patch heat sealing and bonding structure of a lithium battery film and a preparation method thereof
By setting a PP material layer in the overlapping area of the top patch and insulating film of the lithium battery pack and then hot-pressing and curing it, the problem of top patch edge lifting is solved, achieving high-strength adhesion and stability, suitable for automated production, reducing the edge lifting rate and improving assembly efficiency.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHENZHEN CENT POWER TECH
- Filing Date
- 2026-03-28
- Publication Date
- 2026-07-14
AI Technical Summary
During the lithium battery packing process, the overlapping area between the top patch and the insulating film PP material is not firmly bonded, which can easily lead to edge lifting, causing the top patch to fall off or the cell to short-circuit. Moreover, the existing process cannot guarantee long-term stability and consistency.
The hot stamping bonding technology is adopted. By setting the first and second PP material layers in the overlapping area of the top patch and the insulating film, the hot stamping head is used to hot press and then cool and solidify, so that the two PP material layers melt and form an integral bond. The overlap width is 3mm to 5mm, the hot stamping temperature is 100℃ to 180℃, the pressure is 0.3MPa to 0.5MPa, and the time is 2 seconds to 3 seconds.
It significantly improves the peel strength of the overlapping area to over 5 N/cm, reduces the warping rate by over 90%, has high process stability, is adaptable to PP layers of different thicknesses, does not damage insulation performance, is suitable for automated production lines, and improves assembly efficiency.
Smart Images
Figure CN122393577A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of lithium battery manufacturing technology, and particularly relates to a hot-stamping adhesive structure for the top patch of a lithium battery pack and its preparation method. Background Technology
[0002] In the coating process of lithium batteries (such as 314Ah and 348Ah energy storage batteries), an insulating film (such as PET insulating film) is usually wrapped on the surface of the cell casing to achieve insulation and protection. At the same time, a top patch (mostly made of insulating material, used for further isolation of electrodes or marking) is attached to the top of the cell. If the overlapping area between the top patch and the insulating film is not firmly bonded, it is easy for the edge to lift up, which will increase the risk of the top patch falling off during subsequent battery pack assembly, short circuit of the cell, or affect the assembly efficiency due to edge lifting and jamming.
[0003] In existing technologies, the adhesion between the top patch and the insulating film largely relies on the film's own adhesiveness (such as pre-coating an adhesive layer on the insulating film surface). However, during cell storage, transportation, or changes in ambient temperature, the overlapping area is prone to separation and lifting due to adhesive attenuation or external friction. Some existing processes use manual pressing to enhance adhesion, but this results in poor consistency and cannot guarantee long-term stability. Other solutions use room-temperature pressurization equipment, but the adhesion effect on PP material (the overlapping area of the top patch and insulating film often has a PP layer attached to improve temperature resistance) is limited, and the lifting problem remains difficult to solve.
[0004] Therefore, there is an urgent need for a structure and process that can achieve high-strength and stable adhesion in the overlapping areas of PP materials, so as to fundamentally prevent the problem of the top patch lifting. Summary of the Invention
[0005] This invention provides a hot-stamping adhesive structure for the top patch of a lithium battery pack and its preparation method, aiming to solve the problems of poor adhesion of the PP layer attached to the overlapping area of the top patch and the insulating film, which easily leads to the separation or curling of the top patch.
[0006] On one hand, this application provides a top patch heat-bonding structure for a lithium battery pack, applicable to battery cells, including an insulating film, a top patch, and a heat-bonding part; the insulating film covers the outer surface of the battery cell and forms an overlapping area at the top edge of the battery cell; the top patch is attached to the top of the battery cell, and the edge of the top patch overlaps with the overlapping area through the heat-bonding part, the overlap width being 3mm to 5mm.
[0007] In a preferred embodiment, the peel strength of the heat-bonded portion is ≥5N / cm.
[0008] In a preferred embodiment, a first PP material layer is provided on the surface of the overlapping area; a second PP material layer is provided on the side of the top patch near the overlapping area; the first PP material layer and the second PP material layer are cooled and solidified after hot pressing to form an integral hot-pressed part.
[0009] In a preferred embodiment, the thickness of the first PP material layer is 0.03mm to 0.05mm; the thickness of the second PP material layer is 0.03mm to 0.05mm.
[0010] In a preferred embodiment, the temperature of the hot pressing is 100℃~180℃, the pressure is 0.3MPa~0.5MPa, and the time is 2 seconds~3 seconds.
[0011] In a preferred embodiment, the cooling and curing pressure is 0.3 MPa to 0.5 MPa, and the time is 1 to 2 seconds. This allows the two PP material layers to melt and solidify into a single bond.
[0012] On the other hand, embodiments of this application also provide a method for preparing the top patch heat-bonded structure of the lithium battery pack, including the following steps:
[0013] S01. An insulating film is wrapped around the outer surface of the battery cell and an overlapping area is formed at the top edge of the battery cell; a first PP material layer is disposed on the surface of the overlapping area;
[0014] S02. The top patch is attached to the top of the battery cell, and the edge of the top patch overlaps with the first PP material layer through the second PP material layer, the overlap width being 3mm to 5mm;
[0015] S03. The overlapping area is hot-pressed using a hot stamping head, and then cooled and solidified to obtain the hot-stamped adhesive structure of the top patch of the lithium battery pack.
[0016] In a preferred embodiment, in step S01,
[0017] The thickness of the first PP material layer is 0.03mm to 0.05mm.
[0018] In a preferred embodiment, in step S02,
[0019] The thickness of the second PP material layer is 0.03mm to 0.05mm.
[0020] In a preferred embodiment, in step S03...
[0021] The hot pressing and extrusion process is carried out at a temperature of 100℃ to 180℃, a pressure of 0.3MPa to 0.5MPa, and a time of 2 to 3 seconds.
[0022] The cooling and solidification pressure is 0.3MPa to 0.5MPa, and the time is 1 second to 2 seconds.
[0023] The pressure of the hot pressing is the same as the pressure of the cooling and solidification.
[0024] The shape of the working surface of the heating head is adapted to the contour of the overlapping area; the working surface of the heating head is provided with an anti-stick coating (such as Teflon). This prevents the PP material layer from sticking to the heating head when it melts; during the heating process, the battery cell needs to be fixed by a positioning fixture to prevent the battery cell from shifting due to the heating pressure.
[0025] Compared with the prior art, the technical solution of the embodiments of the present invention has the following beneficial effects:
[0026] (1) Significant anti-warping effect: The hot-stamped adhesive part is obtained by hot-stamping and melting the first PP material layer and the second PP material layer and then curing and bonding. The peel strength of the overlapping area is increased to more than 5N / cm. Compared with the traditional structure that only relies on adhesive layer bonding, the warping rate is reduced by more than 90%.
[0027] (2) Strong adaptability: The structure of this application can be compatible with PP layers of different thicknesses (0.03-0.05mm) without damaging the insulation performance of the insulating film and the top patch.
[0028] (3) High process stability: The hot stamping temperature, pressure and time parameters of this application are controllable and can be realized by automated equipment, avoiding the inconsistency of manual operation, and the bonding effect is stable.
[0029] (4) Efficiency improvement: The single hot stamping time of this application is only 2-3 seconds, which can be integrated into the automated film coating production line without affecting the overall production capacity, and no secondary reinforcement process is required afterward. Attached Figure Description
[0030] 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.
[0031] Figure 1 This is a schematic diagram of the overlapping area between the top patch and the insulating film in an embodiment of the present invention;
[0032] Figure 2 This is a cross-sectional schematic diagram of the heat-bonded part (showing the integral structure after the PP layer has melted and solidified);
[0033] Figure 3This is a schematic flowchart of the preparation method according to an embodiment of this application. Detailed Implementation
[0034] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.
[0035] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, top, bottom, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicators will also change accordingly.
[0036] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., 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, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.
[0037] It should be noted that when a component is described as "fixed to" or "set on" another component, it can be directly on the other component or there may be an intervening component. When a component is described as "connected to" another component, it can be directly connected to the other component or there may be an intervening component.
[0038] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.
[0039] This invention aims to solve the problem of edge lifting caused by poor adhesion between the top patch and the PP material of the insulating film during the lithium battery packing process, and can effectively improve the adhesion reliability of the top patch.
[0040] Specifically, on the one hand, such as Figures 1 to 2 As shown in the figure, this application provides a top patch heat-bonding structure for a lithium battery pack, applicable to a battery cell 100, including an insulating film 10, a top patch 20, and a heat-bonding part 30; the insulating film 10 covers the outer surface of the battery cell 100 and forms an overlapping area 40 at the top edge of the battery cell 100; the top patch 20 is attached to the top of the battery cell 100, and the edge of the top patch 20 overlaps with the overlapping area 40 through the heat-bonding part 30, the overlap width being 3mm to 5mm.
[0041] In a preferred embodiment, the peel strength of the heat-bonded portion 30 is ≥5 N / cm. In this embodiment, the peel strength of the heat-bonded portion 30 is 6.2 N / cm.
[0042] In a preferred embodiment, a first PP material layer 41 is provided on the surface of the overlapping area 40; a second PP material layer 21 is provided on the side of the top patch 20 near the overlapping area 40; the first PP material layer 41 and the second PP material layer 21 are cooled and cured after hot pressing to form an integral hot-pressed adhesive part 30.
[0043] In this application, the overlapping area (3-5mm wide) is flat and wrinkle-free. The deviation of the overlap width is ≤0.5mm, and initial pressing ensures that there are no air bubbles in the overlap area.
[0044] In a preferred embodiment, the thickness of the first PP material layer 41 is 0.03mm to 0.05mm; the thickness of the second PP material layer 21 is 0.03mm to 0.05mm.
[0045] In a preferred embodiment, the temperature of the hot pressing is 100℃~180℃, the pressure is 0.3MPa~0.5MPa, and the time is 2 seconds~3 seconds.
[0046] In a preferred embodiment, the cooling and curing pressure is 0.3 MPa to 0.5 MPa, and the time is 1 to 2 seconds. This allows the two PP material layers to melt and solidify into a single bond.
[0047] On the other hand, embodiments of this application also provide a method for preparing the top patch heat-bonded structure of the lithium battery pack, including the following steps:
[0048] S01. An insulating film is wrapped around the outer surface of the battery cell and an overlapping area is formed at the top edge of the battery cell; a first PP material layer is disposed on the surface of the overlapping area;
[0049] S02. The top patch is attached to the top of the battery cell, and the edge of the top patch overlaps with the first PP material layer through the second PP material layer, the overlap width being 3mm to 5mm;
[0050] S03. The overlapping area is hot-pressed using a hot stamping head, and then cooled and solidified to obtain the hot-stamped adhesive structure of the top patch of the lithium battery pack.
[0051] In a preferred embodiment, in step S01,
[0052] The thickness of the first PP material layer is 0.03mm to 0.05mm.
[0053] In a preferred embodiment, in step S02,
[0054] The thickness of the second PP material layer is 0.03mm to 0.05mm.
[0055] In a preferred embodiment, in step S03...
[0056] The hot stamping extrusion temperature is 100℃~180℃ (matching the melting temperature of PP material), the pressure is 0.3MPa~0.5MPa, and the time is 2 seconds~3 seconds (to ensure that the two PP material layers are partially melted and fully contacted).
[0057] The cooling and curing pressure is 0.3MPa to 0.5MPa, and the time is 1 to 2 seconds (to solidify the molten PP material into an integral adhesive).
[0058] The pressure of the hot pressing is the same as the pressure of the cooling and solidification.
[0059] The working surface of the heating head is shaped to match the contour of the overlapping area; an anti-stick coating (such as Teflon) is provided on the working surface of the heating head. This prevents the PP material layer from sticking to the heating head when it melts; during the heating process, the battery cell needs to be fixed by a positioning fixture to prevent displacement of the battery cell due to heating pressure. The heating head is equipped with temperature control and pressure adjustment functions.
[0060] After cooling and curing, an edge warping test is performed: the edge of the top patch is photographed using a visual inspection device to check for any warping (a warping height ≥ 0.3mm is defined as unacceptable). If it passes the test, it proceeds to the next process; otherwise, it is reworked and re-ironed.
[0061] In one embodiment, the parameters of the top patch heat-bonded structure of the lithium battery pack are as follows:
[0062] - Insulating film: PET material, 0.08mm thick, with an overlap area of 3-5mm at the top edge, and a PP layer thickness of 0.03-0.05mm on the surface;
[0063] -Top patch: Insulating material, size matches the top of the cell, overlap width of edge and insulating film overlap area mm, PP layer thickness on contact side 0.03-0.05mm;
[0064] -Hot-bonded area: Covers the entire overlapping area, peel strength test result is 6.2 N / cm.
[0065] The preparation method of the hot-stamping adhesive structure of the top patch of the above lithium battery pack is as follows:
[0066] S01, Insulation film coating: The insulation film is coated onto the outer shell of the 314 and 348Ah energy storage cells by an automated coating machine. The top overlapping area is flat and the PP layer is wrinkle-free.
[0067] S02, Top Patch Positioning: The robotic arm picks up the top patch, aligns it, and attaches it to the top of the battery cell. It is initially pressed to remove air bubbles, and the overlap width deviation is controlled within ± patch positioning.
[0068] S03. Hot stamping and extrusion: The hot stamping head (working surface is a 4mm wide rectangle with Teflon coating) is heated to 140℃ and pressed into the overlapping area with a pressure of 0.4MPa for 2.5 seconds. Then, it is cooled with a pressure of 0.2MPa for 1.5 seconds to obtain the hot stamping and bonding structure of the top patch of the lithium battery pack.
[0069] The hot-stamped bonding structure of the top patch of the lithium battery pack prepared in the above embodiment was tested: the edge of the top patch was photographed by a vision camera. Only 3 out of 1000 samples showed slight edge lifting (qualified), and there was no obvious edge lifting phenomenon, which is a significant improvement compared with the traditional process (edge lifting rate of 15%).
[0070] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A top patch heat-bonding structure for a lithium battery pack, characterized in that, Applicable to battery cells, including an insulating film, a top patch, and a heat-sealing adhesive portion; the insulating film covers the outer surface of the battery cell and forms an overlapping area at the top edge of the battery cell; the top patch is attached to the top of the battery cell, and the edge of the top patch overlaps with the overlapping area through the heat-sealing adhesive portion, the overlap width being 3mm to 5mm.
2. The top patch heat-bonding structure of the lithium battery pack according to claim 1, characterized in that, The peel strength of the heat-bonded part is ≥5N / cm.
3. The top patch heat-bonding structure of the lithium battery pack according to claim 1, characterized in that, A first PP material layer is provided on the surface of the overlapping area; a second PP material layer is provided on the side of the top patch near the overlapping area; the first PP material layer and the second PP material layer are cooled and solidified after hot pressing to form an integral hot-pressed part.
4. The top patch heat-bonding structure of the lithium battery pack according to claim 3, characterized in that, The thickness of the first PP material layer is 0.03mm to 0.05mm; the thickness of the second PP material layer is 0.03mm to 0.05mm.
5. The top patch heat-bonding structure of the lithium battery pack according to claim 3, characterized in that, The hot pressing and extrusion process is carried out at a temperature of 100℃ to 180℃, a pressure of 0.3MPa to 0.5MPa, and a time of 2 to 3 seconds.
6. The top patch heat-bonding structure of the lithium battery pack according to claim 3, characterized in that, The cooling and solidification pressure is 0.3MPa to 0.5MPa, and the time is 1 second to 2 seconds.
7. A method for preparing the top patch heat-bonded structure of the lithium battery pack according to any one of claims 1 to 6, characterized in that, Includes the following steps: S01. An insulating film is wrapped around the outer surface of the battery cell and an overlapping area is formed at the top edge of the battery cell; a first PP material layer is disposed on the surface of the overlapping area; S02. The top patch is attached to the top of the battery cell, and the edge of the top patch overlaps with the first PP material layer through the second PP material layer, the overlap width being 3mm to 5mm. S03. The overlapping area is hot-pressed using a hot stamping head, and then cooled and solidified to obtain the hot-stamped adhesive structure of the top patch of the lithium battery pack.
8. The method for preparing the top patch heat-bonded structure of the lithium battery pack according to claim 7, characterized in that, In step S01, the thickness of the first PP material layer is 0.03mm to 0.05mm; In step S02, the thickness of the second PP material layer is 0.03mm to 0.05mm.
9. The method for preparing the top patch heat-bonded structure of the lithium battery pack according to claim 7, characterized in that, In step S03, the temperature of the hot pressing is 100℃~180℃, the pressure is 0.3MPa~0.5MPa, and the time is 2 seconds~3 seconds; the pressure of the cooling and curing is 0.3MPa~0.5MPa, and the time is 1 second~2 seconds.
10. The method for preparing the top patch heat-bonded structure of the lithium battery pack according to claim 7, characterized in that, The pressure of the hot pressing is the same as the pressure of the cooling and solidification. The shape of the working surface of the hot iron head is adapted to the contour of the overlapping area; an anti-stick coating is provided on the working surface of the hot iron head.