Low-temperature explosion-proof tab adhesive film for soft package lithium battery and preparation method of low-temperature explosion-proof tab adhesive film

Abstract

The invention belongs to the technical field of tab adhesive films for lithium batteries, and particularly relates to a low-temperature explosion-proof tab adhesive film for a soft package lithium battery and a preparation method thereof, and the low-temperature explosion-proof tab adhesive film comprises a first hot melt adhesive layer, a framework layer and a second hot melt adhesive layer which are sequentially laminated; the components of the first hot melt adhesive layer and the second hot melt adhesive layer comprise one or a mixture of more than one of anhydride grafted ethylene-vinyl acetate copolymer, anhydride grafted polyolefin and anhydride grafted polyolefin elastomer substances; the skeleton layer comprises one or a mixture of more than one of polypropylene, polyethylene, acrylic acid grafted polyolefin, methyl methacrylate grafted polyolefin, anhydride grafted polyolefin, dibutyl maleate grafted polyolefin, an anhydride grafted polyolefin elastomer and an anhydride grafted styrene-ethylene-butadiene copolymer; wherein the melting temperature of the first hot melt adhesive layer and the second hot melt adhesive layer is not higher than 105 DEG C.

Description

Technical Field

[0001] This invention belongs to the technical field of electrode film for lithium batteries, specifically relating to a low-temperature explosion-proof electrode film for soft-pack lithium batteries and its preparation method. Background Technology

[0002] Currently, lithium batteries are widely used in consumer electronics, automotive, and energy storage. Energy density has always been a key performance target for lithium batteries, while safety is increasingly becoming a crucial consideration.

[0003] In the manufacturing process of lithium batteries, the tabs are a crucial component, serving as metallic conductors that connect the positive and negative electrodes from the battery cell. A tab is composed of two parts: a metal strip and a tab adhesive film. The tab adhesive film's function is to prevent short circuits between the metal strip and the aluminum-plastic film during battery encapsulation, and to heat-seal the tabs together with the aluminum-plastic film during encapsulation to prevent leakage. The tab consists of two layers of tab adhesive film, with the metal strip sandwiched between them. Existing lithium battery tab adhesive films include a first hot-melt adhesive layer, a barrier layer, and a second hot-melt adhesive layer.

[0004] The tab film is heat-sealed onto the metal tabs and into the aluminum-plastic film. Heat seal strength and electrolyte resistance are key performance indicators. To ensure effective heat seal strength, the tab film is typically heat-sealed at 170-190℃. This means that abnormal heating of the lithium battery can only be detected at higher temperatures, posing a significant safety hazard.

[0005] It should be noted that the information disclosed in this background section is only for understanding the background technology of the present application concept, and therefore, the above description is not considered to constitute prior art information. Summary of the Invention

[0006] This disclosure provides at least one low-temperature explosion-proof tab film for soft-pack lithium batteries and its preparation method.

[0007] In a first aspect, embodiments of this disclosure provide a low-temperature explosion-proof tab film for soft-pack lithium batteries, comprising a first hot melt adhesive layer, a skeleton layer, and a second hot melt adhesive layer stacked sequentially; the components of the first and second hot melt adhesive layers include one or more mixtures of anhydride-grafted ethylene-vinyl acetate copolymer, anhydride-grafted polyolefin, and anhydride-grafted polyolefin elastomer; the components of the skeleton layer include one or more mixtures of polypropylene, polyethylene, acrylic acid-grafted polyolefin, methyl methacrylate-grafted polyolefin, anhydride-grafted polyolefin, dibutyl maleate-grafted polyolefin, anhydride-grafted polyolefin elastomer, and anhydride-grafted styrene-ethylene-butadiene copolymer; wherein the melting temperature of the first and second hot melt adhesive layers is not higher than 105°C.

[0008] In one optional embodiment, the components of the first hot melt adhesive layer and the second hot melt adhesive layer include the following components by mass parts: 5-10 parts of anhydride-grafted ethylene-vinyl acetate copolymer, 5-50 parts of anhydride-grafted polyethylene, 20-90 parts of anhydride-grafted polypropylene, and 1-5 parts of additives.

[0009] In one optional embodiment, the adjuvant comprises the following components by mass parts: 20-50 parts of hindered phenolic antioxidant, 20-50 parts of benzotriazole UV stabilizer, and 20-50 parts of antistatic stabilizer.

[0010] In one optional embodiment, the components of the skeleton layer include the following components by mass parts: 5-20 parts of anhydride-grafted polyethylene, 5-20 parts of anhydride-grafted polypropylene, 15-30 parts of polyethylene, and 20-60 parts of polypropylene.

[0011] In one optional embodiment, the total thickness of the first hot melt adhesive layer, the skeleton layer, and the second hot melt adhesive layer is 80–280 μm; wherein, the single-layer thickness of the first hot melt adhesive layer and the second hot melt adhesive layer is 10–100 μm; and the thickness of the skeleton layer is 30–180 μm.

[0012] Secondly, this disclosure also provides a method for preparing a low-temperature explosion-proof tab film for soft-pack lithium batteries as described above, comprising the following steps: Step S1, mixing raw materials to obtain a first raw material mixture, a second raw material mixture, and a third raw material mixture; Step S2, melting and plasticizing the raw material mixture to obtain a first resin melt, a second resin melt, and a third resin melt; Step S3, filtering the resin melt through a filter screen; Step S4, extruding the filtered resin melt through an extruder; Step S5, stacking and casting the extruded resin melt in the order of the first resin melt, the third resin melt, and the second resin melt onto a cooling roller to obtain a low-temperature explosion-proof tab film for soft-pack lithium batteries.

[0013] In an optional embodiment, step S1 includes the following steps: S11, adding the anhydride-grafted ethylene-vinyl acetate copolymer and anhydride-grafted polyolefin particles and additives of the first hot melt adhesive layer into the first conveying tank and mixing them with a mixer at a temperature of 25-50°C, a stirring speed of 5-150 r / min, and a stirring time of 60-90 min to form a first raw material mixture; S12, adding the anhydride-grafted ethylene-vinyl acetate copolymer and anhydride-grafted polyolefin particles of the second hot melt adhesive layer... The particles and additives are added to the second feeding tank and mixed using a mixer at a temperature of 25–50°C, a stirring speed of 5–150 r / min, and a stirring time of 60–90 min to form the second raw material mixture; S13, the grafted modified polyolefin particles of the skeleton layer are added to the third feeding tank and mixed using a mixer at a temperature of 25–50°C, a stirring speed of 5–150 r / min, and a stirring time of 60–90 min to form the third raw material mixture.

[0014] In one optional embodiment, step S2 includes the following steps: S21, feeding the mixed first raw material mixture through the feeding port of the first extruder, and then performing melt plasticization treatment in the extruder to form a first resin melt; S22, feeding the mixed second raw material mixture through the feeding port of the second extruder, and then performing melt plasticization treatment in the extruder to form a second resin melt; S23, feeding the mixed third raw material mixture through the feeding port of the third extruder, and then performing melt plasticization treatment in the extruder to form a third resin melt; wherein the processing temperature gradient is 180℃, 200℃, 220℃, 240℃, 240℃, 260℃, and 270℃.

[0015] In one optional embodiment, in step S3, the filter mesh size of the first resin melt is 10-220 mesh, the filter mesh size of the second resin melt is 10-220 mesh, and the filter mesh size of the third resin melt is 10-220 mesh.

[0016] In one optional embodiment, the die temperature of the extruder in step S4 is 220–270°C.

[0017] In one optional embodiment, the cooling roller in step S5 includes a first cooling roller and a second cooling roller, wherein the temperature of the first cooling roller is 25-45°C and the temperature of the second cooling roller is 10-30°C.

[0018] Thirdly, this disclosure also provides a pouch lithium battery, including the low-temperature explosion-proof tab film for pouch lithium batteries as described above.

[0019] The beneficial effects of this invention are that the low-temperature explosion-proof tab adhesive film for soft-pack lithium batteries and its preparation method, by setting a first hot melt adhesive layer and a second hot melt adhesive layer with low melting temperature, enable them to melt at 105°C and achieve delamination opening between the tab and the lithium battery electrode at 105-115°C. This allows the pressure to be released in time before the abnormal heating of the lithium battery module causes a sharp rise in internal pressure, avoiding the long-term accumulation of energy that could reach higher temperatures, causing violent explosions and combustion, thus improving the safety of lithium batteries.

[0020] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention are realized and obtained through the structures particularly pointed out in the description.

[0021] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described in detail below. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, 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.

[0023] As used herein, the phrases “in one embodiment,” “according to one embodiment,” “in some embodiments,” etc., generally refer to the fact that a particular feature, structure, or characteristic following the phrase can be included in at least one embodiment of this disclosure. Therefore, a particular feature, structure, or characteristic can be included in more than one embodiment of this disclosure, such that these phrases do not necessarily refer to the same embodiment. As used herein, the terms “example,” “exemplary,” etc., are used to “serve as an example, instance, or illustration.” Any implementation, aspect, or design described herein as “example” or “exemplary” is not necessarily to be construed as preferred or superior to other implementations, aspects, or designs. Rather, the use of the terms “example,” “exemplary,” etc., is intended to present concepts in a specific manner.

[0024] In this document, as used herein, expressions such as “at least one of…” modify the entire list of elements when following a list of elements, rather than individual elements in the list. For example, the expression “at least one of a, b, and c” should be understood to include only a, only b, only c, both a and b, both a and c, both b and c, or all of a, b, and c.

[0025] The terminology used herein is for the purpose of describing specific exemplary configurations only and is not intended to be limiting. As used herein, the singular articles “a,” “an,” and “the” may also be intended to include plural forms unless otherwise clearly stated herein. The terms “comprising,” “including,” and “having” are inclusive and thus specify the presence of features, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or combinations thereof. The method steps, processes, and operations described herein should not be construed as requiring them to be performed in the specific order discussed or shown, unless specifically identified as such. Additional or alternative steps may be employed.

[0026] The following describes some embodiments of the present invention in detail. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0027] This disclosure provides a low-temperature explosion-proof tab film for soft-pack lithium batteries, comprising a first hot melt adhesive layer, a skeleton layer, and a second hot melt adhesive layer stacked sequentially. The components of the first and second hot melt adhesive layers include one or more mixtures of anhydride-grafted ethylene-vinyl acetate copolymer, anhydride-grafted polyolefin, and anhydride-grafted polyolefin elastomer. The components of the skeleton layer include one or more mixtures of polypropylene, polyethylene, acrylic acid-grafted polyolefin, methyl methacrylate-grafted polyolefin, anhydride-grafted polyolefin, dibutyl maleate-grafted polyolefin, anhydride-grafted polyolefin elastomer, and anhydride-grafted styrene-ethylene-butadiene copolymer. The melting temperature of the first and second hot melt adhesive layers is not higher than 105°C.

[0028] In some embodiments, specifically, the components of the first hot melt adhesive layer and the second hot melt adhesive layer include the following components by mass parts: 5-10 parts of anhydride-grafted ethylene-vinyl acetate copolymer, 5-50 parts of anhydride-grafted polyethylene, 20-90 parts of anhydride-grafted polypropylene, and 1-5 parts of additives.

[0029] In some embodiments, the additives specifically include the following components by mass parts: 20-50 parts of hindered phenolic antioxidant, 20-50 parts of benzotriazole UV stabilizer, and 20-50 parts of antistatic stabilizer.

[0030] In some embodiments, the components of the skeleton layer specifically include the following components by mass parts: 5-20 parts of anhydride-grafted polyethylene, 5-20 parts of anhydride-grafted polypropylene, 15-30 parts of polyethylene, and 20-60 parts of polypropylene.

[0031] In some embodiments, the total thickness of the first hot melt adhesive layer, the skeleton layer, and the second hot melt adhesive layer is 80–280 μm; wherein the single-layer thickness of the first hot melt adhesive layer and the second hot melt adhesive layer is 10–100 μm; and the thickness of the skeleton layer is 30–180 μm.

[0032] This disclosure also provides a method for preparing a low-temperature explosion-proof tab film for pouch lithium batteries as described above, comprising the following steps: Step S1, mixing raw materials to obtain a first raw material mixture, a second raw material mixture, and a third raw material mixture; Step S2, melting and plasticizing the raw material mixture to obtain a first resin melt, a second resin melt, and a third resin melt; Step S3, filtering the resin melt through a filter screen; Step S4, extruding the filtered resin melt separately through an extruder; Step S5, stacking and casting the extruded resin melt in the order of the first resin melt, the third resin melt, and the second resin melt onto a cooling roller to obtain a low-temperature explosion-proof tab film for pouch lithium batteries.

[0033] In some embodiments, step S1 specifically includes the following steps: S11, adding the anhydride-grafted ethylene-vinyl acetate copolymer and anhydride-grafted polyolefin particles and additives of the first hot melt adhesive layer into the first conveying tank and mixing them with a mixer at a temperature of 25-50°C, a stirring speed of 5-150 r / min, and a stirring time of 60-90 min to form a first raw material mixture; S12, adding the anhydride-grafted ethylene-vinyl acetate copolymer and anhydride-grafted polyolefin particles of the second hot melt adhesive layer... The particles and additives are added to the second feeding tank and mixed using a mixer at a temperature of 25–50°C, a stirring speed of 5–150 r / min, and a stirring time of 60–90 min to form the second raw material mixture; S13, the grafted modified polyolefin particles of the skeleton layer are added to the third feeding tank and mixed using a mixer at a temperature of 25–50°C, a stirring speed of 5–150 r / min, and a stirring time of 60–90 min to form the third raw material mixture.

[0034] In some embodiments, step S2 specifically includes the following steps: S21, feeding the mixed first raw material mixture through the feeding port of the first extruder, and then performing melt plasticization treatment in the extruder to form a first resin melt; S22, feeding the mixed second raw material mixture through the feeding port of the second extruder, and then performing melt plasticization treatment in the extruder to form a second resin melt; S23, feeding the mixed third raw material mixture through the feeding port of the third extruder, and then performing melt plasticization treatment in the extruder to form a third resin melt; wherein the processing temperature gradient is 180℃, 200℃, 220℃, 240℃, 240℃, 260℃, and 270℃.

[0035] In some embodiments, specifically, the mesh aperture of the filter screen of the first resin melt in step S3 is 10-220 mesh, the mesh aperture of the filter screen of the second resin melt is 10-220 mesh, and the mesh aperture of the filter screen of the third resin melt is 10-220 mesh.

[0036] In some embodiments, specifically, the die head temperature of the extruder in step S4 is 220-270 °C.

[0037] In some embodiments, specifically, the cooling roller in step S5 includes a first cooling roller and a second cooling roller. The temperature of the first cooling roller is 25-45 °C, and the temperature of the second cooling roller is 10-30 °C.

[0038] The embodiment of the present disclosure also provides a soft-pack lithium battery, including the low-temperature explosion-proof tab adhesive film for soft-pack lithium batteries as described above.

[0039] Example 1, a preparation method of a low-temperature explosion-proof tab adhesive film for a soft-pack lithium battery, includes the following steps: Step S1, mixing raw materials to obtain a first raw material mixture, a second raw material mixture, and a third raw material mixture; S11, adding 5 parts of acid anhydride grafted ethylene-vinyl acetate copolymer, 20 parts of acid anhydride grafted polyethylene, 72 parts of acid anhydride grafted polypropylene, and 3 parts of additives (hindered phenolic antioxidant RIANOX1520: brand Rianlon / Lian Anlong 25 parts; benzotriazole ultraviolet stabilizer UV-234: brand Milan New Materials 25 parts; antistatic stabilizer ACCUREL SF 261: brand EVONIK / Evonik 50 parts) into the first feeding barrel and mixing them through a mixing blender. With a temperature of 30 °C, a stirring speed of 65 / min, and a stirring time of 60 min, stirring treatment is carried out to form a first raw material mixture; S12, the second hot-melt adhesive layer is the same as the first hot-melt adhesive layer to form a second raw material mixture; S13, adding 50 parts of graft-modified polyolefin particles of the backbone layer into the third feeding barrel and mixing them through a mixing blender. With a temperature of 30 °C, a stirring speed of 65 r / min, and a stirring time of 60 min, stirring treatment is carried out to form a third raw material mixture; Step S2, melting and plasticizing the raw material mixture to obtain a first resin melt, a second resin melt, and a third resin melt; S21, the first raw material mixture is fed through the feeding port of the first extruder and then melted and plasticized in the extruder to form a first resin melt; S22, the second raw material mixture is fed through the feeding port of the second extruder and then melted and plasticized in the extruder to form a second resin melt; S23, the third raw material mixture is fed through the feeding port of the third extruder and then melted and plasticized in the extruder to form a third resin melt; wherein the processing temperature gradient is 180℃, 200℃, 220℃, 240℃, 240℃, 260℃, 270℃; Step S3: Filter the resin melt using a filter screen. The filter screen for the first resin melt has a pore size of 110 mesh, the filter screen for the second resin melt has a pore size of 110 mesh, and the filter screen for the third resin melt has a pore size of 110 mesh. Step S4: The filtered resin melt is cast and extruded separately through an extruder, and the die temperature of the extruder is 270°C. Step S5: The extruded resin melt is layered and cast onto a cooling roller in the order of first resin melt, third resin melt, and second resin melt. The cooling roller includes a first cooling roller and a second cooling roller. The temperature of the first cooling roller is 30°C and the temperature of the second cooling roller is 20°C, thereby obtaining a low-temperature explosion-proof tab film for soft-pack lithium batteries.

[0040] Example 2, based on Example 1, adjusts the first hot melt adhesive layer to consist of 7 parts anhydride-grafted ethylene-vinyl acetate copolymer, 20 parts anhydride-grafted polyethylene, 70 parts anhydride-grafted polypropylene, and 3 parts additives. The second hot melt adhesive layer is the same as the first hot melt adhesive layer.

[0041] Example 3, based on Example 1, adjusts the first hot melt adhesive layer to consist of 10 parts of anhydride-grafted ethylene-vinyl acetate copolymer, 20 parts of anhydride-grafted polyethylene, 67 parts of anhydride-grafted polypropylene, and 3 parts of additives. The second hot melt adhesive layer is the same as the first hot melt adhesive layer.

[0042] Example 4: Based on Example 1, the first hot melt adhesive layer was adjusted to consist of 5 parts anhydride-grafted ethylene-vinyl acetate copolymer, 5 parts anhydride-grafted polyethylene, 87 parts anhydride-grafted polypropylene, and 3 parts additives. The second hot melt adhesive layer was the same as the first hot melt adhesive layer.

[0043] Example 5: Based on Example 1, the first hot melt adhesive layer was adjusted to consist of 5 parts anhydride-grafted ethylene-vinyl acetate copolymer, 15 parts anhydride-grafted polyethylene, 77 parts anhydride-grafted polypropylene, and 3 parts additives. The second hot melt adhesive layer was the same as the first hot melt adhesive layer.

[0044] Example 6: Based on Example 1, the first hot melt adhesive layer was adjusted to consist of 5 parts anhydride-grafted ethylene-vinyl acetate copolymer, 25 parts anhydride-grafted polyethylene, 67 parts anhydride-grafted polypropylene, and 3 parts additives. The second hot melt adhesive layer was the same as the first hot melt adhesive layer.

[0045] Example 7: Based on Example 1, the first hot melt adhesive layer was adjusted to consist of 5 parts anhydride-grafted ethylene-vinyl acetate copolymer, 35 parts anhydride-grafted polyethylene, 57 parts anhydride-grafted polypropylene, and 3 parts additives. The second hot melt adhesive layer was the same as the first hot melt adhesive layer.

[0046] Example 8: Based on Example 1, the first hot melt adhesive layer was adjusted to consist of 5 parts anhydride-grafted ethylene-vinyl acetate copolymer, 45 parts anhydride-grafted polyethylene, 47 parts anhydride-grafted polypropylene, and 3 parts additives. The second hot melt adhesive layer was the same as the first hot melt adhesive layer.

[0047] Comparative Example 1 Based on Example 1, the first hot melt adhesive layer consists of 20 parts of anhydride-grafted polyethylene, 79 parts of anhydride-grafted polypropylene, and 1 part of additives. The second hot melt adhesive layer is the same as the first hot melt adhesive layer.

[0048] Specifically, the performance of the low-temperature explosion-proof tab film for soft-pack lithium batteries obtained in Examples 1-8 was tested, and the results are shown in Table 1 below.

[0049] Table 1. Performance test results of aluminum-plastic films from Examples 1-8 and Comparative Example 1.

[0050] In summary, the low-temperature explosion-proof tab adhesive film for this soft-pack lithium battery and its preparation method, by setting a first hot melt adhesive layer and a second hot melt adhesive layer with low melting temperatures, enable it to melt at 105℃ and achieve delamination opening between the tab and the lithium battery electrode at 105-115℃. This allows the pressure to be released in time before the abnormal heating of the lithium battery module causes a sharp rise in internal pressure, preventing energy from accumulating for a long time and reaching higher temperatures, thus avoiding violent explosions and combustion, and improving the safety of the lithium battery.

[0051] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A low-temperature explosion-proof tab film for soft-pack lithium batteries, characterized in that, It includes a first hot melt adhesive layer, a skeleton layer, and a second hot melt adhesive layer that are stacked in sequence; The components of the first hot melt adhesive layer and the second hot melt adhesive layer include one or more of the following: anhydride-grafted ethylene-vinyl acetate copolymer, anhydride-grafted polyolefin, and anhydride-grafted polyolefin elastomer. The components of the skeleton layer include one or more of the following: polypropylene, polyethylene, acrylic acid grafted polyolefin, methyl methacrylate grafted polyolefin, acid anhydride grafted polyolefin, dibutyl maleate grafted polyolefin, acid anhydride grafted polyolefin elastomer, and acid anhydride grafted styrene-ethylene-butadiene copolymer. The melting temperature of the first hot melt adhesive layer and the second hot melt adhesive layer is not higher than 105°C.

2. The low-temperature explosion-proof tab film for soft-pack lithium batteries as described in claim 1, characterized in that, The components of the first hot melt adhesive layer and the second hot melt adhesive layer, by mass parts, include the following components: 5-10 parts of anhydride-grafted ethylene-vinyl acetate copolymer, 5-50 parts of anhydride-grafted polyethylene, 20-90 parts of anhydride-grafted polypropylene, and 1-5 parts of additives.

3. The low-temperature explosion-proof tab film for soft-pack lithium batteries as described in claim 2, characterized in that, The auxiliary agent comprises the following components by mass parts: 20-50 parts hindered phenolic antioxidant, 20-50 parts benzotriazole UV stabilizer, and 20-50 parts antistatic stabilizer.

4. The low-temperature explosion-proof tab film for soft-pack lithium batteries as described in claim 1, characterized in that, The components of the skeleton layer, by mass parts, include the following components: Anhydride-grafted polyethylene 5-20 parts, anhydride-grafted polypropylene 5-20 parts, polyethylene 15-30 parts, polypropylene 20-60 parts.

5. The low-temperature explosion-proof tab film for soft-pack lithium batteries as described in claim 1, characterized in that, The total thickness of the first hot melt adhesive layer, the skeleton layer, and the second hot melt adhesive layer is 80–280 μm; The thickness of a single layer of the first hot melt adhesive layer and the second hot melt adhesive layer is 10 to 100 μm. The thickness of the skeleton layer is 30–180 μm.

6. A method for preparing a low-temperature explosion-proof tab adhesive film for a soft-pack lithium battery as described in any one of claims 1-5, characterized in that, Includes the following steps: Step S1: Mix the raw materials to obtain a first raw material mixture, a second raw material mixture, and a third raw material mixture; Step S2: The raw material mixture is melted and plasticized to obtain a first resin melt, a second resin melt, and a third resin melt; Step S3: Filter the resin melt through a filter screen; Step S4: The filtered resin melt is cast and extruded separately through an extruder; Step S5: The extruded resin melt is layered and cast onto a cooling roller in the order of first resin melt, third resin melt, and second resin melt to obtain a low-temperature explosion-proof tab film for soft-pack lithium batteries.

7. The preparation method according to claim 1, characterized in that, Step S1 includes the following steps: S11, the anhydride-grafted ethylene-vinyl acetate copolymer of the first hot melt adhesive layer, the anhydride-grafted polyolefin particles and the additives are all added to the first conveying tank and mixed by a mixer at a temperature of 25-50°C, a stirring speed of 5-150 r / min and a stirring time of 60-90 min to form the first raw material mixture. S12, the anhydride-grafted ethylene-vinyl acetate copolymer, anhydride-grafted polyolefin particles, and additives of the second hot melt adhesive layer are all added to the second feeding tank and mixed by a mixer at a temperature of 25-50°C, a stirring speed of 5-150 r / min, and a stirring time of 60-90 min to form the second raw material mixture. S13, the grafted modified polyolefin particles of the skeleton layer are added to the third feeding tank and mixed by a mixer at a temperature of 25-50℃, a stirring speed of 5-150r / min, and a stirring time of 60-90min to form the third raw material mixture.

8. The preparation method according to claim 1, characterized in that, Step S2 includes the following steps: S21, the mixed first raw material mixture is fed through the feeding port of the first extruder, and then melted and plasticized in the extruder to form the first resin melt; S22, the mixed second raw material mixture is fed through the feeding port of the second extruder, and then melted and plasticized in the extruder to form a second resin melt; S23, the mixed third raw material mixture is fed through the feed port of the third extruder, and then melted and plasticized in the extruder to form the third resin melt; The processing temperature gradients are 180℃, 200℃, 220℃, 240℃, 240℃, 260℃, and 270℃.

9. The preparation method according to claim 9, characterized in that, In step S3, the filter screen pore size of the first resin melt is 10-220 mesh, the filter screen pore size of the second resin melt is 10-220 mesh, and the filter screen pore size of the third resin melt is 10-220 mesh. In step S4, the die temperature of the extruder is 220–270°C. In step S5, the cooling rollers include a first cooling roller and a second cooling roller. The temperature of the first cooling roller is 25-45°C, and the temperature of the second cooling roller is 10-30°C.

10. A soft-pack lithium battery, characterized in that, Including the low-temperature explosion-proof tab film for soft-pack lithium batteries as described in any one of claims 1-5.

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