Battery shielding film pressing method

Abstract

The invention discloses a battery shielding film pressing method. The method comprises the following steps: photographing surface characteristics of a battery unit through a visual identification system erected above the battery unit; meanwhile, the position and the outline of the shielding film are photographed through another visual identification system; the central processing unit receives the image information and calculates the relative position deviation between the battery unit and the shielding film through an image processing algorithm; the multi-axis motion platform and / or the shielding film feeding mechanism are / is controlled to carry out fine adjustment and accurate alignment, so that the shielding film is preliminarily aligned with a preset laminating area of the to-be-laminated surface of the battery unit in the three-dimensional space position; according to the invention, high-precision alignment is carried out through a double-vision system, so that the problem of positioning errors caused by manual operation is thoroughly solved; in the pre-activation step, the local adhesive layer firstly generates viscidity, and the central area of the film is fixed; air can be continuously and directionally discharged in a rolling pressing mode, and bubbles and wrinkles are fundamentally eradicated.

Description

Technical Field

[0001] This invention relates to the field of lithium battery manufacturing technology, specifically a method for pressing a battery shielding film. Background Technology

[0002] With the rapid development of new energy vehicles and consumer electronics, the energy density and power density of lithium batteries are constantly increasing, and the electromagnetic interference (EMC) problem generated during their operation is becoming increasingly prominent. To meet electromagnetic compatibility (EMC) requirements, a composite shielding film is usually wrapped around the outside of the battery cell or battery pack. This shielding film is usually a multi-layered structure, including a metal layer (such as aluminum foil), a conductive adhesive layer, and an insulating protective layer.

[0003] Traditional shielding film application processes mainly face the following challenges:

[0004] 1. Poor positioning accuracy: Shielding films are usually large and flexible, and are prone to misalignment or skewing when applied manually or by simple mechanical means, which affects the product's appearance and shielding effectiveness.

[0005] 2. Air bubbles and wrinkles: During the bonding process, air bubbles will form if it becomes trapped and cannot escape. Simultaneously, improper tension control can easily lead to wrinkles. These problems not only affect aesthetics but may also cause localized failure of the shielding layer, delamination, or even puncture of the battery cell insulation layer, posing a safety hazard.

[0006] 3. Inefficiency: Traditional methods rely on manual operation, resulting in poor consistency, low production efficiency, and difficulty in meeting the needs of large-scale automated production.

[0007] 4. Adhesive pre-activation issue: Conductive adhesives typically require specific temperature and pressure to achieve optimal adhesion. Insufficient flow and wetting of the adhesive during one-time pressing affects the final bond strength and conductivity.

[0008] Therefore, there is an urgent need for a high-precision, high-efficiency, high-quality battery shielding film lamination method that is suitable for automated production. Summary of the Invention

[0009] The technical problem solved by this invention is to propose a battery shielding film lamination method and system based on "pre-positioning-pre-activation-rolling hot pressing". This method can effectively improve the adhesion accuracy, eliminate bubbles and wrinkles, and enhance the bonding reliability.

[0010] To achieve the above objectives, the present invention provides the following technical solution: a method for laminating a battery shielding film, comprising the following steps:

[0011] S1: Prepare and fix the battery unit (such as a cell, module or battery pack housing) to be covered with the shielding film; provide a sheet shielding film of matching size, the shielding film including at least an insulating outer layer, a metal shielding layer and a conductive adhesive inner layer; fix the battery unit on a programmable multi-axis motion platform.

[0012] S2: Visual pre-positioning uses a visual recognition system (such as a CCD camera) mounted above the battery cell to photograph the surface features (such as edges and corner markers) of the battery cell; simultaneously, another visual recognition system photographs the position and outline of the shielding film; the central processing unit (such as a PLC or industrial PC) receives the image information and calculates the relative positional deviation (ΔX, ΔY, Δθ) between the battery cell and the shielding film using image processing algorithms; it controls the multi-axis motion platform and / or the shielding film feeding mechanism to make fine adjustments and precise alignment, so that the shielding film is initially aligned with the predetermined bonding area of ​​the battery cell in three-dimensional space.

[0013] S3: Pre-contact and pre-activation After alignment is completed, a pre-pressing mechanism with heating function is moved above the shielding film; the heating plate of the pre-pressing mechanism is brought into contact with a local area (preferably the middle or an edge) of the shielding film under a small initial pressure (P1, for example 0.1-0.5 bar); the heating plate is heated to a pre-activation temperature (T1, lower than or equal to the final curing temperature of the conductive adhesive, for example 80-110°C), and the contact is maintained for a period of time (t1, for example 1-5 seconds) to initially soften and activate the conductive adhesive layer in the contact area, giving it initial tackiness but not complete curing.

[0014] S4: Rolling hot pressing removes the pre-pressing mechanism; controls a rolling pressing device with integrated heating function to move above the pre-activated area; the rolling pressing device includes a heatable silicone roller or metal roller (with an embedded heating element), a servo pressure mechanism for controlling the pressing pressure (P2), and a real-time temperature measuring element; presses the rollers at a set main pressing temperature (T2, slightly higher than T1, e.g., 100-130°C) and main pressing pressure (P2, e.g., 1.0-3.0 bar) onto the pre-activated area or starting from its edge; activates the multi-axis motion platform to smoothly move the battery cell along a preset path (e.g., a straight line or a curve), or controls the rolling pressing device itself to move so that the rollers roll relative to the surface of the battery cell; during the rolling process, the heat and pressure of the rollers continue to act, gradually rolling and covering the shielding film from the pre-activated area outwards, completely expelling air from the center to the edge or from one side to the other.

[0015] S5: After the overall rolling is completed by holding pressure and cooling, the roller can maintain pressure in the end area of ​​the shielding film for a moment (t2, for example, 2-8 seconds) to ensure that the end is firmly bonded; remove the roller and let the attached battery cell complete the final curing of the conductive adhesive under natural cooling or forced air cooling.

[0016] Preferably, in step S2, the vision system can also be used to detect whether there are defects (such as damage or foreign objects) on the surface of the shielding film.

[0017] Preferably, the heating plate surface of the pre-pressing mechanism is coated with an anti-stick coating (such as Teflon) to prevent it from sticking to the shielding film.

[0018] Preferably, the rollers of the rolling pressing device are coated with a high-temperature resistant and elastic silicone layer to better adapt to the slight unevenness of the battery cell surface and ensure uniform pressure distribution.

[0019] Preferably, the multi-axis motion platform is a six-axis robot or a high-precision XYθ platform.

[0020] The present invention also claims protection for an automated pressing system for implementing the above method, comprising:

[0021] • Rack and workbench;

[0022] • Battery cell fixing and positioning fixture;

[0023] • Automatic feeding and cutting unit for shielding film;

[0024] • As mentioned above, a multi-axis motion platform;

[0025] • Visual positioning system;

[0026] • Pre-compression heating mechanism;

[0027] • Rolling hot pressing mechanism;

[0028] • Central processing unit, used to coordinate and control the sequential operation of various components.

[0029] Compared with the prior art, the beneficial effects of the present invention are:

[0030] 1. High-precision attachment: High-precision alignment is achieved through a dual vision system, completely solving the positioning error problem caused by manual operation.

[0031] 2. Near-zero defects: The "pre-activation" step makes the local adhesive layer sticky first, fixing the central area of ​​the film; the "rolling pressing" method can continuously and directionally expel air, fundamentally eliminating the generation of bubbles and wrinkles.

[0032] 3. High bonding strength: The staged temperature and pressure control (pre-activation + main pressing) allows the conductive adhesive to flow and wet fully, forming a stronger and more conductive bonding interface with the battery casing surface.

[0033] 4. Automation and high efficiency: The entire process can be integrated into automated equipment without human intervention, which greatly improves production efficiency and product consistency, making it very suitable for large-scale industrial mass production. Detailed Implementation

[0034] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] This invention provides a technical solution:

[0036] Example: A square power battery with an aluminum shell covered by an overall shielding film is used as an example.

[0037] 1. The robot places and secures the battery casing (1) onto the gripper of the six-axis robot (3).

[0038] 2. The feeding mechanism delivers the cut shielding film (2) to the station to be applied.

[0039] 3. The vision camera (4) takes pictures of the upper surface of the battery casing and the shielding film respectively. After the computer corrects the position, the robot adjusts its posture to align the film with the upper surface of the casing.

[0040] 4. The pre-pressed heating plate (5) (temperature set at 95°C) descends and makes light contact with the center area of ​​the shielding film (pressure 0.3 bar), holds for 3 seconds, and then lifts up.

[0041] 5. The heated silicone roller (6) (temperature set at 115°C) is moved to the pre-pressed center area and pressed with a pressure of 1.5 bar.

[0042] 6. The six-axis robot (3) moves smoothly along the preset straight path, and the silicone rollers then press and attach the shielding film from the center to both sides. The whole process lasts about 15 seconds.

[0043] 7. After application, the silicone roller is lifted after holding pressure at the end for 5 seconds.

[0044] 8. The robot moves the battery casing with the shielding film applied to it to the cooling area.

[0045] Upon inspection, the positional accuracy of the applied shielding film was within ±0.2mm, and there were no visible bubbles or wrinkles on the surface. The peel strength test results were more than 30% better than those of traditional processes.

[0046] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A battery barrier film lamination method characterized by: The method comprises the following steps: S1, preparation and fixation: providing a battery cell to be attached with a shielding film; providing a size-matched shielding film in a sheet shape; fixing the battery cell on a programmable multi-axis motion platform; S2, visual pre-positioning: taking a photo of the surface features of the battery cell by a visual recognition system arranged above the battery cell; at the same time, taking a photo of the position and contour of the shielding film by another visual recognition system; receiving the image information by a central processing unit, calculating the relative positional deviation between the battery cell and the shielding film by an image processing algorithm; controlling the multi-axis motion platform and / or the shielding film feeding mechanism to make fine adjustment and accurate alignment, so that the shielding film is preliminarily aligned with the pre-attached surface of the battery cell in the three-dimensional space; S3, pre-contact and pre-activation: after the alignment is completed, a pre-pressing mechanism with a heating function is controlled to move above the shielding film; the heating plate of the pre-pressing mechanism is contacted with the local area of the shielding film under a small initial pressure; the heating plate is heated to a pre-activation temperature, and the contact is maintained for a period of time, so that the conductive adhesive layer in the contact area is preliminarily softened and activated, and has initial adhesion but is not completely solidified; S4, rolling hot pressing: the pre-pressing mechanism is removed; a rolling pressing device integrated with a heating function is controlled to move above the pre-activated area; the roller is pressed against the pre-activated area or starts from the edge thereof at a set main pressing temperature and main pressing pressure; the multi-axis motion platform is started to move the battery cell along a preset path smoothly, or the rolling pressing device is controlled to move itself, so that the roller rolls relative to the surface of the battery cell; during the rolling, the heat and pressure of the roller continuously act on the shielding film, which is gradually rolled and attached from the pre-activated area to the surrounding area, and air is completely discharged from the center to the edge or from one side to the other side; S5, pressure maintaining and cooling: after the rolling is completed, the roller maintains the pressure on the end area of the shielding film for a period of time to ensure that the end area is firmly attached; the roller is removed, and the attached battery cell is cooled naturally or by forced air cooling to complete the final solidification of the conductive adhesive.

2. The battery barrier film lamination method according to claim 1, characterized by: In the step S1, the shielding film comprises an insulating outer layer, a metal shielding layer and a conductive adhesive inner layer.

3. The battery barrier film lamination method of claim 1, wherein: In the step S3, the local area of the shielding film is one of the middle part or one edge.

4. The battery barrier film lamination method of claim 1, wherein: In the step S4, the rolling pressing device comprises a heatable silica gel roller or metal roller, a servo pressure mechanism for controlling the pressing pressure, and a real-time temperature measuring element.

5. The battery barrier film lamination method of claim 1, wherein: In the step S2, the visual system can also be used to detect whether there is a defect on the surface of the shielding film.

6. The battery barrier film lamination method of claim 1, wherein: The surface of the heating plate of the pre-pressing mechanism is coated with an anti-sticking coating.

7. The battery barrier film lamination method of claim 1, wherein: The surface of the roller of the rolling pressing device is wrapped with a high-temperature-resistant and elastic silica gel layer to better adapt to the slight unevenness of the surface of the battery cell.

8. The battery barrier film lamination method of claim 1, wherein: The multi-axis motion platform is a six-axis robot or a high-precision XYθ platform.

9. A battery barrier film lamination system for carrying out the process of any one of claims 1-8, characterized by: It comprises a rack and a workbench; a battery cell fixing and positioning clamp; a shielding film automatic feeding and cutting unit; the multi-axis motion platform of claim 1; a visual positioning system; a pre-pressing heating mechanism; a rolling hot pressing mechanism; A central processing unit is used to coordinate the sequential operation of the various components.