Pre-treatment method of uv-coated battery cell and battery cell

Abstract

The application provides a UV-coated battery cell pretreatment method and a battery cell. The UV-coated battery cell pretreatment method comprises the following steps: S1, providing an outer protective film, and performing corona treatment on the outer protective film; S2, performing activation treatment on a surface of a battery cell shell; S3, attaching the outer protective film to the surface of the battery cell shell; and S4, before UV coating, irradiating the outer protective film and the surface of the battery cell shell with high-energy ultraviolet laser, so that the outer protective film is peeled off from the surface of the battery cell shell. The application solves the problem of low battery cell coating efficiency in the related art.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of batteries, in particular to a pretreatment method for UV coating of a battery cell and the battery cell. BACKGROUND

[0002] At present, new energy vehicles are developing rapidly, and power batteries, as an important component of new energy vehicles, have attracted widespread attention. Most of the existing battery cell packaging methods use PET film packaging process. However, the existing film packaging process has some problems, mainly including: low shear strength, easy to cause damage to the blue film after being scratched by external force, thereby affecting the insulation of the battery cell; the blue film process is easy to produce bubbles, affecting the cycle and storage life of the battery cell; the blue film process is low in efficiency, affecting the production efficiency.

[0003] At present, the main alternative to the blue film is insulation spraying, among which the UV spraying process is widely used due to its high environmental protection, high shear strength and fast curing speed. However, it also exposes many problems. Since the main components of UV are epoxy resin and polyurethane, etc., the production process of the battery cell is affected by the external environment, which can cause scratches and dirt layers on the surface of the battery cell, affecting the printing effect. In order to improve the appearance problem, an external protective film is attached to the surface of the battery cell shell during the manufacturing process to improve the cleanliness of the battery cell surface. Although the introduction of the external protective film can reduce scratches and dirt during the production process of the battery cell, the adhesive substances on the external protective film can form an oil-repellent layer on the surface of the battery cell, which is difficult to clean, resulting in a significant decrease in the coating yield.

[0004] As can be seen from the above, the related art has the problem of low coating yield of the battery cell. SUMMARY

[0005] The main purpose of the present application is to provide a pretreatment method for UV coating of a battery cell and the battery cell, so as to solve the problem of low coating yield of the battery cell in the related art.

[0006] In order to achieve the above-mentioned purpose, according to one aspect of the present application, a pretreatment method for UV coating of a battery cell is provided, comprising: step S1: providing an external protective film and performing corona treatment on the external protective film; step S2: performing activation treatment on the surface of the battery cell shell; step S3: attaching the external protective film to the surface of the battery cell shell; and step S4: before UV coating, irradiating the external protective film and the surface of the battery cell shell with high-energy ultraviolet laser to make the external protective film peel off from the surface of the battery cell shell.

[0007] Further, the material of the external protective film is one or more of PP, PET, PA, PVC, PS, PU, PC, PI.

[0008] Further, the material of the external protective film is PU.

[0009] Furthermore, in step S1 , a corona treatment machine is used for corona treatment, and the AC voltage of the corona treatment machine is 5000V to 15000V; and / or the output power of the corona treatment machine is 20kW to 70kW.

[0010] Furthermore, the AC voltage of the corona treater is 10000V to 12000V; and / or the output power of the corona treater is 30kW to 60kW.

[0011] Furthermore, in step S2, a low-temperature plasma machine is used for activation treatment, and the holding pressure of the low-temperature plasma machine is 10Pa to 150Pa.

[0012] Furthermore, the holding pressure of the low-temperature plasma machine is 50Pa to 100Pa.

[0013] Furthermore, in step S4, the irradiation time of the high-energy ultraviolet laser is 2s to 4s; and / or the wavelength of the high-energy ultraviolet laser is 300nm to 400nm; and / or the power density of the high-energy ultraviolet laser is 20MW / cm 2 Up to 60MW / cm 2 .

[0014] Furthermore, after the outer protective film is attached to the surface of the battery cell shell, step S3 further includes: performing a hot pressing treatment on the outer protective film and the surface of the battery cell shell.

[0015] Furthermore, during the hot pressing treatment, the hot pressing pressure is 100 kgf to 300 kgf; and / or the hot pressing temperature is 50° C. to 100° C.; and / or the hot pressing time is 10 s to 20 s.

[0016] According to another aspect of the present invention, a battery cell is further provided, and the above-mentioned pretreatment method for UV-coated battery cells is used to prepare the battery cell.

[0017] The UV-coated battery cell pre-processing method of the application comprises the following steps: S1, providing an outer protective film and performing corona treatment on the outer protective film; S2, performing activation treatment on the surface of the battery cell shell; S3, attaching the outer protective film to the surface of the battery cell shell; and S4, before UV coating, irradiating the outer protective film and the surface of the battery cell shell with high-energy ultraviolet laser to separate the outer protective film from the surface of the battery cell shell. The surface roughness and polarity of the outer protective film can be increased by performing corona pre-treatment on the outer protective film, thereby improving the surface energy and performing activation pre-treatment on the surface of the battery cell shell to form a series of covalent bonds on the surface of the battery cell shell, thereby increasing the adhesion of the surface of the battery cell shell and the protective film. That is, the surface of the battery cell shell and the outer protective film are combined by intermolecular forces rather than using adhesive substances to attach the outer protective film. The intermolecular forces between the surface of the battery cell shell and the outer protective film can be destroyed by irradiating with high-energy ultraviolet laser before UV coating, thereby separating the surface of the battery cell shell and the outer protective film, so that the surface of the battery cell shell does not remain adhesive substances, greatly improving the battery cell coating yield and solving the problem of low battery cell coating yield in the related art. BRIEF DESCRIPTION OF DRAWINGS

[0018] The accompanying drawings, which form a part of this application, are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification. The illustrations in the drawings for the purpose of exemplification only and serve to provide one skilled in the art with a working description of the application. In the drawings:

[0019] Figure 1 A flowchart of a UV-coated battery cell pre-processing method according to one embodiment of the application is shown. DETAILED DESCRIPTION

[0020] The technical solutions in the embodiments of the application will be clearly and completely described below with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments of the application. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the application and its applications or uses. Based on the embodiments in the application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of the application.

[0021] It should be noted that the terms used herein are only intended to describe specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, the singular form is intended to include the plural form unless the context clearly indicates otherwise, and it should also be understood that when the terms "comprise" and / or "include" are used in the specification, there is a presence of a feature, step, operation, device, component and / or combinations thereof.

[0022] The relative arrangement of parts and steps, numerical expressions, and numerical values set forth in the examples herein are not intended to limit the scope of the application unless specifically so stated. It is to be understood that the drawings are not necessarily to scale as the dimensions of the parts shown are for the purpose of illustration and description only and not to limit the scope of the application. Techniques, methods, and apparatus known to those of ordinary skill in the relevant art can not be discussed in detail but are intended to be understood as a part of the specification when appropriate. In all examples shown and discussed herein, any specific values are to be interpreted as merely illustrative and not as a limitation on the scope of the exemplary embodiments. Thus, other examples of the exemplary embodiments can have different values. It is noted that like numbers and letters refer to like elements throughout the several views of the drawings and, as such, no further discussion with regard thereto is needed.

[0023] In order to solve the problem of low coating yield of the battery cell in the related art, the application provides a pretreatment method for UV coating of a battery cell and the battery cell.

[0024] As shown in Figure 1 The pretreatment method for UV coating of the battery cell comprises the following steps: S1, providing an outer protective film and performing corona treatment on the outer protective film; S2, performing activation treatment on the surface of the battery cell shell; S3, attaching the outer protective film to the surface of the battery cell shell; and S4, before UV coating, irradiating the outer protective film and the surface of the battery cell shell with high-energy ultraviolet laser to separate the outer protective film from the surface of the battery cell shell.

[0025] By performing corona pretreatment on the outer protective film, the surface roughness and polarity of the outer protective film can be increased, so that the surface energy is improved, and the surface of the battery cell shell is activated and pretreated, so that a series of covalent bonds are formed on the surface of the battery cell shell, and the adhesion of the battery cell shell surface to the protective film is increased. That is to say, the surface of the battery cell shell and the outer protective film are combined by intermolecular forces rather than using adhesive substances to attach the outer protective film. Before UV coating, irradiation with high-energy ultraviolet laser can destroy the intermolecular forces between the surface of the battery cell shell and the outer protective film, separate the surface of the battery cell shell and the outer protective film, so that the surface of the battery cell shell does not remain adhesive substances, and the coating yield of the battery cell is greatly improved.

[0026] In this embodiment, the battery cell shell can be an aluminum shell.

[0027] In this embodiment, in step S1, a corona treatment machine is used for corona treatment. Specifically, the corona treatment generates a high-voltage electric field on the surface of the outer protective film, ionizes the molecules in the air, and the active particles generated react with the surface of the outer protective film, which can increase the surface roughness and polarity of the outer protective film, thereby improving the surface energy.

[0028] In the embodiment, the AC voltage of the corona treatment machine is 5000V to 15000V. The output power of the corona treatment machine is 20kW to 70kW.

[0029] Preferably, the AC voltage of the corona treatment machine is 10000V to 12000V. The output power of the corona treatment machine is 30kW to 60kW.

[0030] In the embodiment, in step S2, the activation treatment is performed using a low-temperature plasma machine. Specifically, the electronic devices, positive ions and oxygen radicals caused by the plasma technology collide with the monomolecular structure in the liquid phase, thereby forming a series of covalent bonds on the surface of the battery shell, increasing the adhesion of the surface of the battery shell and the outer protective film. Among them, the low-temperature plasma machine can be divided into two types, number tube type and bell jar type, and the number tube type is preferred.

[0031] In the embodiment, the pressure maintaining pressure of the low-temperature plasma machine is 10Pa to 150Pa.

[0032] Preferably, the pressure maintaining pressure of the low-temperature plasma machine is 50Pa to 100Pa.

[0033] In the embodiment, the material of the outer protective film is selected to be a plastic with special functional groups, such as a plastic containing polar groups such as hydroxyl, carboxyl, amine group, etc. These groups can form strong intermolecular forces such as hydrogen bonds, ionic bonds, etc. with the metal surface. Specifically, the material of the outer protective film is one or more of PP (polypropylene), PET (polyethylene terephthalate), PA (polyamide), PVC (polyvinyl chloride), PS (polystyrene), PU (polyurethane), PC (polycarbonate), PI (polyimide).

[0034] Preferably, the material of the outer protective film is PU.

[0035] In the embodiment, after the outer protective film is attached to the surface of the battery shell, step S3 further includes: performing heat pressing treatment on the outer protective film and the surface of the battery shell. Specifically, a heat press machine is used to attach the outer protective film to the surface of the battery shell, and high temperature and pressure can increase the vibration of atoms and molecules inside the material, thereby increasing the peeling force between the metal and the outer protective film.

[0036] In the embodiment, when performing heat pressing treatment, the heat pressing pressure is 100kgf to 300kgf. The heat pressing temperature is 50℃ to 100℃. The heat pressing time is 10s to 20s.

[0037] In the embodiment, in step S4, the irradiation time of the high-energy ultraviolet laser is 2s to 4s. The wavelength of the high-energy ultraviolet laser is 300nm to 400nm. The power density of the high-energy ultraviolet laser is 20MW / cm 2 to 60MW / cm2 .

[0038] The pretreatment method of the present application will be specifically described below with specific examples and comparative examples.

[0039] Example One

[0040] The pretreatment method of the UV-coated battery cell provided in the present embodiment comprises:

[0041] Step S1: providing an outer protective film, the material of the outer protective film is PU, and the outer protective film is subjected to corona pretreatment using a corona treatment machine, the alternating voltage of the corona treatment machine is 11000V, and the power is 45kW;

[0042] Step S2: activating the surface of the battery cell shell, using a multi-tube low-temperature plasma machine to activate the surface of the battery cell shell, the holding pressure is 80Pa;

[0043] Step S3: outer protective film lamination, using a hot press to heat press the surface of the pretreated battery cell shell and the outer protective film, the hot press time is 15s, the hot press pressure is 200kgf, and the hot press temperature is 80℃;

[0044] Step S4: peeling off the outer protective film, using high-energy ultraviolet laser to irradiate the outer protective film and the surface of the battery cell shell, the irradiation time is 3s, the wavelength is 350nm, and the power density is 40MW / cm 2 .

[0045] Example Two

[0046] Compared with Example One, the material of the outer protective film is changed from PU to PP; the alternating voltage of the corona treatment machine is 10000V, and the power is 30kW; the holding pressure of the multi-tube low-temperature plasma machine is 50Pa; the hot press time is 10s, the hot press pressure is 150kgf, and the hot press temperature is 60℃; the irradiation time of the high-energy ultraviolet laser is 2s, the wavelength is 350nm, and the power density is 30MW / cm 2 .

[0047] Example Three

[0048] Compared with Example One, the alternating voltage of the corona treatment machine is 12000V, and the power is 50kW; a bell jar type low-temperature plasma machine is used, the holding pressure is 90Pa; the hot press time is 20s, the hot press pressure is 250kgf, and the hot press temperature is 100℃; the irradiation time of the high-energy ultraviolet laser is 4s, the wavelength is 390nm, and the power density is 55MW / cm 2 .

[0049] Comparative Example One

[0050] The pretreatment method of the UV-coated battery cell provided in the present embodiment comprises:

[0051] Step S1: providing an outer protective film of PU material with adhesion;

[0052] Step S2: activating the surface of the battery shell, using a multi-tube low-temperature plasma machine to activate the surface of the battery shell, with a holding pressure of 80 Pa;

[0053] Step S3: outer protective film lamination, using the adhesion of the PU film itself for lamination;

[0054] Step S4: stripping the outer protective film.

[0055] Comparative Example Two

[0056] This comparative example provides a pretreatment method for UV-coated batteries, including:

[0057] Step S1: providing an outer protective film, the outer protective film material is PU, using a corona treatment machine to treat the outer protective film, the alternating voltage is 11000V, and the power is 45kW;

[0058] Step S2: protective film lamination, using a hot press to heat press the surface of the pretreated battery shell and the outer protective film, the hot pressing time is 15s, the hot pressing pressure is 200kgf, and the hot pressing temperature is 80℃;

[0059] Step S3: stripping the outer protective film, using high-energy ultraviolet laser to irradiate the outer protective film and the surface of the battery shell, the irradiation time is 3s, the wavelength is 350nm, and the power density is 40MW / cm 2 .

[0060] In this embodiment, the battery coating process is as follows:

[0061] Step one: laser cleaning: turn on the power of the laser cleaning machine, laser and cooling water; turn on the laser and CCD software; adjust the button to automatic gear and click reset; set the laser cleaning parameters to 1kW to 1.5kW; press the "start" button to start the equipment;

[0062] Step two: spray printing: turn on the power of the spray equipment; press the "start" key of the equipment, select "pole, large surface and bottom surface", and then spray the reverse surface; load the material, and after the spraying is completed, perform high-temperature ultraviolet curing, with the parameters being: UVA≥1100MW / cm 2 , UVB≥1000MW / cm 2 , UVC≥500MW / cm 2 , UVV≥1500MW / cm 2 , time≥10s, temperature≤70℃, after the battery spray printing is completed, unload the material and turn off the equipment.

[0063] In the present embodiment, the cell appearance defect test process is as follows:

[0064] Confirm that the environmental conditions are normal: light intensity: 600LUX to 1000LUX, no lamp tube damage or flicker.

[0065] The position of the fluorescent lamp must be kept directly above the material, at a distance of 80±20cm.

[0066] The top cover to be inspected is at a 90° angle to the line of sight of the inspector, and the distance between the top cover and the eye is about 45cm.

[0067] When one angle cannot be effectively observed during inspection, the cell must be rotated along its axis to change the angle of observation.

[0068] Table 1: Comparison table of cell appearance defect ratio

[0069]

[0070] As can be seen from the data in Table 1, the appearance yield of the coated cell is lower than that of the prior art, and the cell appearance defect prepared by the pretreatment method provided by the present application is less, and the appearance is more excellent, thereby improving the problem of low coating yield caused by the oil-repellent layer of the residual adhesive material of the traditional outer protective film on the surface of the cell shell.

[0071] In the present embodiment, the cell coating peeling strength test process is as follows:

[0072] The sprayed cell is fixed on the surface of the peeling strength tester, and the adhesive layer with an area of 15cm 2 is attached to the sprayed layer to ensure that the surface is bubble-free, and is left to stand for 10 minutes. The other end of the adhesive layer is connected to the other end of the tester, and the maximum peeling force during the peeling process is measured to determine the peeling strength.

[0073] Peeling strength formula: σ (peeling strength, unit MPa) = F (maximum peeling force, unit N) / S (adhesive layer area, unit cm 2 )

[0074] Table 2: Comparison table of cell coating peeling strength

[0075]

[0076] As can be seen from the data in Table 2, the peeling strength of the cell coating obtained by coating after using the pretreatment method provided by the present application is higher than that of the prior art.

[0077] The present application also provides a cell, and the above-mentioned UV coating cell pretreatment method is used to prepare the cell. The cell prepared by the above-mentioned pretreatment method has a high coating yield.

[0078] From the above description, it can be seen that the above-mentioned embodiments of the present application achieve the following technical effects: by using the above-mentioned pretreatment method, the surface roughness and polarity of the outer protective film can be increased by carrying out corona pretreatment on the outer protective film, so as to improve the surface energy, and the surface of the battery cell shell is activated and pretreated, so as to form a series of covalent bonds on the surface of the battery cell shell, thereby increasing the adhesion between the surface of the battery cell shell and the protective film, that is, the surface of the battery cell shell and the outer protective film are combined by intermolecular forces instead of using adhesive substances to attach the outer protective film, and the high-energy ultraviolet laser irradiation before UV coating can destroy the intermolecular forces between the surface of the battery cell shell and the outer protective film, so as to separate the surface of the battery cell shell and the outer protective film, so that the surface of the battery cell shell does not remain adhesive substances, and the battery cell coating success rate is greatly improved.

[0079] In the description of the present application, it should be understood that the orientation words such as "front, back, up, down, left, right", "transverse, vertical, perpendicular, horizontal" and "top, bottom" and the like indicate the orientation or positional relationship shown in the drawings, which are only for the convenience of describing the present application and simplifying the description, and in the absence of the opposite description, these orientation words do not indicate and imply that the devices or elements referred to must have a specific orientation or be constructed and operated in a specific orientation, therefore cannot be understood as a limitation on the scope of protection of the present application; the orientation words "inner, outer" refer to the inner and outer of the contour of each component itself.

[0080] For the convenience of description, spatial relative terms such as "on", "above", "upper surface", "upper" and the like can be used herein to describe the spatial positional relationship of one device or feature with respect to other devices or features as shown in the drawings. It should be understood that the spatial relative terms are intended to include different orientations in use or operation in addition to the orientation of the devices described in the drawings. For example, if the devices in the drawings are inverted, the device described as "above" or "on" other devices or structures will be positioned "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below" orientations. The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein are interpreted accordingly.

[0081] In addition, it should be noted that the use of the words "first", "second" and the like to define parts is only for the convenience of distinguishing the corresponding parts, and the above words have no special meaning unless otherwise stated, therefore cannot be understood as a limitation on the scope of protection of the present application.

[0082] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A pretreatment method for UV coating battery cells, characterized in that: include: Step S1: providing an outer protective film, and performing corona treatment on the outer protective film; Step S2: activating the surface of the battery cell shell; Step S3: attaching the outer protective film to the surface of the battery cell shell; Step S4: before UV coating, using a high-energy ultraviolet laser to irradiate the outer protective film and the surface of the battery cell shell to peel the outer protective film from the surface of the battery cell shell; In the step S2, the activation treatment is performed using a low-temperature plasma machine; In step S4, the power density of the high energy ultraviolet laser is 20 MW / cm 2 Up to 60MW / cm 2 .

2. The pretreatment method for UV-coated battery cells according to claim 1, characterized in that: The material of the outer protective film is one or more of PP, PET, PA, PVC, PS, PU, ​​PC, and PI.

3. The pretreatment method for UV-coated battery cells according to claim 2, characterized in that: The material of the outer protective film is PU.

4. The pretreatment method for UV-coated battery cells according to claim 1, characterized in that: In the step S1, a corona treatment machine is used to perform the corona treatment. The AC voltage of the corona treater is 5000V to 15000V; and / or The output power of the corona treater is 20 kW to 70 kW.

5. The pretreatment method for UV-coated battery cells according to claim 4, characterized in that: The AC voltage of the corona treater is 10000V to 12000V; and / or The output power of the corona treater is 30 kW to 60 kW.

6. The pretreatment method for UV-coated battery cells according to claim 1, characterized in that: In step S2, the holding pressure of the low-temperature plasma machine is 10Pa to 150Pa.

7. The pretreatment method for UV-coated battery cells according to claim 6, characterized in that: The holding pressure of the low-temperature plasma machine is 50Pa to 100Pa.

8. The pretreatment method for UV-coated battery cells according to claim 1, characterized in that: In step S4, The irradiation time of the high-energy ultraviolet laser is 2s to 4s; and / or The wavelength of the high-energy ultraviolet laser is 300nm to 400nm.

9. The pretreatment method for UV-coated battery cells according to claim 1, characterized in that: After the outer protective film is attached to the surface of the battery cell shell, step S3 further includes: The outer protective film and the surface of the battery cell shell are subjected to hot pressing treatment.

10. The pretreatment method for UV-coated battery cells according to claim 9, wherein: During the hot pressing treatment, Hot pressing pressure is 100kgf to 300kgf; and / or Hot pressing temperature is 50°C to 100°C; and / or The hot pressing time is 10s to 20s.

11. A battery cell, characterized in that: The pretreatment method for UV-coated battery cells according to any one of claims 1 to 10 is used to prepare the battery cells.

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