CN114316822B - Tab film, preparation method thereof, tab and battery - Google Patents

Abstract

The application provides a tab film, a tab and a battery, wherein the tab film is used for being applied to two sides of a metal belt of the tab, and comprises a first PP layer, a first bonding PP layer, a first adhesive layer, a high-temperature-resistant middle layer, a second adhesive layer, a second bonding PP layer and a second PP layer which are sequentially laminated on the surface of the metal belt; the first bonding PP layer and the second bonding PP layer both comprise modified polypropylene resin and black master batch; the high temperature resistant interlayer comprises polyethylene terephthalate. The tab film provided by the application has black appearance and better adhesiveness, and can not cause the conditions of material mixing and product collapse when being heat-sealed with the tab and the aluminum plastic film, thereby effectively improving the leakage condition of the battery side hole in the use process of the battery.

Description

Tab film, preparation method thereof, tab and battery

Technical Field

The application belongs to the technical field of tab adhesive films, and particularly relates to a tab adhesive film, a preparation method thereof, a tab and a battery.

Background

The lithium battery as a novel secondary battery has the advantages of high energy density and power density, high working voltage, light weight, small volume, long cycle life, good safety, environmental protection and the like, and has wide application prospect in the aspects of portable electric appliances, electric tools, large-scale energy storage, electric traffic power sources and the like.

The conventional lithium battery generally comprises a battery cell and an aluminum-plastic film for packaging the battery cell, wherein the battery cell is composed of a pole piece and a diaphragm, a pole lug is welded on the pole piece, the positive electrode and the negative electrode of the battery are led out by the pole lug as a metal conductor, and in order to prevent the battery cell from being short-circuited between a metal belt of the pole lug and the aluminum-plastic film during packaging (the short circuit comprises a short circuit between exposed metal at a cutting position of the edge of the metal belt and the edge of the aluminum-plastic film and metal at a seal area), a pole lug film is usually arranged between the pole lug and the aluminum-plastic film to play an insulating role.

Most of the existing tab films are white tab films with three-layer composite layer structures, and different requirements of customers cannot be met. In addition, three composite layers in the existing tab film are easy to mix together, so that materials are mixed, products collapse, and the performance of the tab film is affected.

Disclosure of Invention

The embodiment of the application aims to provide a tab film with black appearance, a preparation method thereof, a tab comprising the tab film and a battery.

In order to achieve the above purpose, the application adopts the following technical scheme: the application provides a tab film, which is used for being applied to two sides of a metal belt of a tab, wherein the tab film comprises a first PP layer, a first bonding PP layer, a first adhesive layer, a high-temperature resistant middle layer, a second adhesive layer, a second bonding PP layer and a second PP layer which are sequentially laminated on the surface of the metal belt; the first bonding PP layer and the second bonding PP layer both comprise modified polypropylene resin and black master batch; the high temperature resistant interlayer comprises polyethylene terephthalate.

Compared with the prior art, the tab film provided by the application is additionally provided with the first bonding PP layer and the second bonding PP layer containing the black master batch, so that the tab film provided by the application has novel black appearance, and different requirements of customers are met. However, the inventors of the present application found that the addition of the black master batch is not good for the material stability and adhesion of the first and second adhesive PP layers, and in this regard, the present application further employs a modified polypropylene resin in the first and second adhesive PP layers, so that the tab film of the present application has a black appearance, and at the same time, has better adhesion, and no material mixing and product collapse occur. In addition, in the tab film, the first PP layer and the second PP layer have better adhesion with the metal surface, the first PP layer is used for being adhered to the metal belt surface, and the second PP layer is used for being adhered to the aluminum plastic film; the high-temperature resistant intermediate layer containing polyethylene terephthalate has excellent high-temperature resistance, so that the tab film provided by the application is improved in the aspects of high-temperature resistance, cohesiveness, product stability and the like.

Preferably, in the tab film provided by the application, the thickness of the high-temperature resistant intermediate layer is 10-15 μm, and more preferably, the thickness of the high-temperature resistant intermediate layer is 12 μm.

Preferably, in the tab film provided by the application, the first PP layer and the second PP layer comprise maleic anhydride modified polypropylene resin with a melt index of 4-7 g/10min, and the thickness of each of the first PP layer and the second PP layer is 20-23 μm independently. The maleic anhydride modified polypropylene resin is used as the raw materials of the first PP layer and the second PP layer, and the melt fingers of the maleic anhydride modified polypropylene resin are guaranteed to be in the range of 4-7 g/10min, so that the first PP layer and the second PP layer have excellent bonding performance with metal materials (such as metal strips and aluminum plastic films), and the tab film has better stability when being heat-sealed with the aluminum plastic films, and is not easy to mix with other layers of materials.

Preferably, in the tab film provided by the application, the modified polypropylene resin is selected from peroxide modified polypropylene resins with a melt index of 9-11 g/10min, wherein the peroxide modified polypropylene resins comprise peroxide and polypropylene resins, and the mass percentage of the peroxide in the peroxide modified polypropylene resins is 5-1%; preferably, the peroxide is diisobenzene peroxide. According to the application, the peroxide modified polypropylene resin with the melt index of 9-11 g/10min is adopted in the first bonding PP layer and the second bonding PP layer, and the mass percentage of the peroxide modified polypropylene resin and the black master batch in the first bonding PP layer or the second bonding PP layer is in a preferred range, so that the first bonding PP layer and the second bonding PP layer are ensured to have better adhesiveness, ageing resistance and stability, and are not easy to mix with other layer materials.

Preferably, in the tab film provided by the application, the thickness of the first bonding PP layer and the second bonding PP layer is 20-23 μm independently.

Preferably, in the tab film provided by the present application, the first adhesive layer and the second adhesive layer are selected from aqueous polyurethane, and the thickness of each of the first adhesive layer and the second adhesive layer is independently 1 to 3 μm.

Preferably, in the tab film provided by the application, the first PP layer and the second PP layer are resistant to temperature of 140-145 ℃; the temperature resistance of the first bonding PP layer and the second bonding PP layer is 150-155 ℃; the high-temperature resistant intermediate layer has a temperature resistance of 260-265 ℃. Therefore, in the tab film provided by the application, a layered composite structure with gradually improved temperature resistance is formed, and the overall high temperature resistance of the tab film is obviously improved.

In summary, the tab film provided by the application comprises seven layers of composite laminated structures which are laminated in sequence, and the traditional white tab film can only resist the temperature of 165 ℃, so that the tab film with black appearance is provided to meet different requirements of customers on the appearance color of the film, the temperature resistance of the black tab film is improved to about 265 ℃, and the material stability of each composite layer is better. Therefore, the tab film provided by the application can be suitable for tabs of lithium batteries and can be applied to tabs of lithium batteries with higher attaching temperature, larger process window and higher product adhesiveness, and the leakage condition of battery side holes in the use process of the lithium batteries can be obviously improved.

The second aspect of the present application provides a method for preparing the tab film according to the first aspect, comprising the following steps:

(1) Preparing a PP layer-bonding PP layer co-extrusion layer: adding the raw materials of the first PP layer and the raw materials of the first bonding PP layer into a co-extrusion device, and co-extruding the two layers to obtain a first PP layer-first bonding PP layer co-extrusion layer; adding the raw materials of the second PP layer and the raw materials of the second bonding PP layer into a co-extrusion device, and co-extruding the two layers to obtain a second PP layer-second bonding PP layer co-extrusion layer;

(2) Preparing a first adhesive layer-high temperature resistant intermediate layer-second adhesive layer composite layer: respectively coating the raw materials of the first adhesive layer and the raw materials of the second adhesive layer on two surfaces of the high-temperature resistant intermediate layer to obtain a first adhesive layer-high-temperature resistant intermediate layer-second adhesive layer composite layer;

(3) Multi-layer compounding: compounding the first PP layer-first bonding PP layer co-extrusion layer on the surface of the first adhesive layer-high temperature resistant middle layer-second adhesive layer composite layer, and enabling the first bonding PP layer to be laminated on the surface of the first adhesive layer; and compounding the second PP layer-second bonding PP layer co-extrusion layer on the surface of the second adhesive layer in the first adhesive layer-high temperature resistant middle layer-second adhesive layer composite layer, and compounding the second bonding PP layer on the surface of the second adhesive layer to obtain the tab film.

The third aspect of the application provides a tab, which comprises a metal belt, wherein tab films are attached to two sides of the metal belt, and the tab films are the tab films according to the first aspect of the application.

According to a fourth aspect of the application, a battery is provided, the battery comprises an aluminum plastic film and the tab, the metal strap of the tab is provided with a first end positioned outside the aluminum plastic film and a second end positioned inside the aluminum plastic film, and the first end of the metal strap is fixedly connected with the aluminum plastic film through the tab film.

The tab film of the first aspect of the application is used in the tab and the battery, so that the tab film has the advantages of being adaptable to higher attaching temperature, larger process window and higher product adhesiveness, and being capable of remarkably improving the leakage condition of the battery side hole in the use process of the lithium battery.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the embodiments or the description of the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and that other drawings can be obtained according to these drawings without inventive effort for a person skilled in the art.

Fig. 1 is a schematic structural diagram of a tab film according to an embodiment of the present application;

fig. 2 is a schematic structural diagram of connection between a tab film, an aluminum plastic film and a tab according to an embodiment of the present application;

fig. 3 is a graph showing the change in peel strength of tab films in example 1 and comparative examples 1 and 2 with the increase in the electrolyte soaking time.

Wherein, each reference sign in the figure:

1-tab film;

2-aluminum plastic film;

3-electrode lugs;

11-a first PP layer;

12-a first adhesive PP layer;

13-a first adhesive layer;

14-a high temperature resistant interlayer;

15-a second adhesive layer;

16-a second tie PP layer;

17-second PP layer.

Detailed Description

For the purpose of making the objects, technical solutions and advantages of the embodiments of the present application more apparent, the technical solutions of the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application, and it is apparent that the described embodiments are some embodiments of the present application, but not all embodiments of the present application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.

In the description of the present application, it should be understood that the terms "comprises" and "comprising," and any variations thereof, as used herein, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements that are expressly listed or inherent to such process, method, article, or apparatus.

Furthermore, in the present application, unless explicitly stated and limited otherwise, the terms "connected," "secured," "mounted," and the like are to be construed broadly, and may be, for example, mechanically or electrically; either directly or indirectly, through intermediaries, or both, unless otherwise specifically defined, the meaning of the terms in this disclosure is to be understood by those of ordinary skill in the art.

It is to be understood that the terms "length," "width," "upper," "lower," "front," "rear," "left," "right," and the like indicate or are based on the orientation or positional relationship shown in the drawings, merely to facilitate describing the present application and simplify the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus should not be construed as limiting the present application.

Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature.

The tab film, tab and battery provided by the application are described in detail below with reference to specific embodiments.

Tab film

Some embodiments of the present application provide a tab film. Fig. 1 is a schematic structural view of a tab film according to an embodiment of the present application, fig. 2 is a schematic structural view of a tab film according to an embodiment of the present application, connected to an aluminum plastic film and a tab, referring to fig. 1 and 2, and referring to fig. 1 and 2, some embodiments of the present application provide a tab film 1, where the tab film 1 is an insulating portion on a tab 3, and is used for sealing between the aluminum plastic film 2 and the tab 3, so as to prevent a short circuit between a metal belt and the aluminum plastic film 2 during battery packaging, and to be sealed and bonded together with the aluminum plastic film 2 by heat and hot melting during packaging to prevent liquid leakage. The tab film 1 according to some embodiments of the present application is used for applying to both sides of a metal tape of the tab 3, and the tab film 1 includes a first PP layer 11, a first adhesive PP layer 12, a first adhesive layer 13, a high temperature resistant intermediate layer 14, a second adhesive layer 15, a second adhesive PP layer 16, and a second PP layer 17 sequentially laminated on the surface of the metal tape. Wherein the first PP layer 11 is in contact with the metal strip of the tab 3, and the second PP layer 17 is in contact with the plastic-aluminum film 2.

The following sections describe each composite layer in the tab film according to some embodiments.

First PP layer/second PP layer

The first PP layer 11/second PP layer 17 comprises a maleic anhydride-modified polypropylene resin having a melt index of 4 to 7g/10 min. The maleic anhydride modified polypropylene resin comprises 90-100 parts by mass of polypropylene resin and 2-10 parts by mass of maleic anhydride, and the thicknesses of the first PP layer 11 and the second PP layer 17 are respectively 20-23 mu m independently. In the tab, the first PP layer 11 is used for adhering to the surface of the metal strip, and the second PP layer 17 is used for adhering to the aluminum plastic film; the maleic anhydride modified polypropylene resin with the mass ratio is used as the raw materials of the first PP layer 11 and the second PP layer 17, and the melt fingers of the maleic anhydride modified polypropylene resin are guaranteed to be in the range of 4-7 g/10min, so that the adhesiveness and compatibility of polar materials and nonpolar materials can be improved, the first PP layer 11, the metal belt, the second PP layer 17 and the aluminum plastic film have excellent adhesive property, and the tab film has better stability when being heat-sealed with the aluminum plastic film, so that the first PP layer 11 and the second PP layer 17 are not easy to mix with other layers of materials.

First and second adhesive PP layers

The first adhesive PP layer 12/second adhesive PP layer 16 comprises a modified polypropylene resin and black master batch. The modified polypropylene resin is peroxide modified polypropylene resin with a melt index of 9-11 g/10min, and the thickness of the first bonding PP layer 12 and the second bonding PP layer 16 is 20-23 mu m independently. In the first bonding PP layer 12/the second bonding PP layer 16, the mass percentage of the peroxide in the peroxide modified polypropylene resin is 5 per mill-1 percent; alternatively, the peroxide used for modifying the polypropylene resin may be a peroxy-O-containing compound, preferably the peroxide is diisobenzene peroxide; for example, it is possible to use: arkema F40P-SP2 diisobenzene peroxide. The black master batch comprises carbon black, and the mass percentage of the black master batch in the first bonding PP layer or the second bonding PP layer is 3-10%. The addition of the black master batch is unfavorable for the material stability and the adhesiveness of the first bonding PP layer 12 and the second bonding PP layer 16, the peroxide modified polypropylene resin with the melt index of 9-11 g/10min is adopted in the first bonding PP layer 12 and the second bonding PP layer 16 in the embodiment of the application, and the mass percentage of the peroxide modified polypropylene resin and the black master batch in the first bonding PP layer 12 or the second bonding PP layer 16 is in a preferred range, so that the first bonding PP layer 12 and the second bonding PP layer 16 are ensured to have better adhesiveness, ageing resistance and stability, and the material mixture and the product collapse of other layers are not easy to occur in the heat sealing process of the tab film and the aluminum plastic film.

First adhesive layer/second adhesive layer

The first adhesive layer 13 and the second adhesive layer 15 are selected from aqueous polyurethane, and the thickness of the first adhesive layer 13 and the second adhesive layer 15 is 1 to 3 μm each independently. In the tab film of the embodiment of the present application, the first adhesive layer 13/the second adhesive layer 15 plays a role of adhesion between the three layers of the first adhesive PP layer 12, the high temperature resistant intermediate layer 14 and the second adhesive PP layer 16.

High temperature resistant interlayer

The high temperature resistant intermediate layer 14 comprises polyethylene terephthalate, and the thickness of the high temperature resistant intermediate layer 14 is 10 to 15 μm, more preferably, the thickness of the high temperature resistant intermediate layer 14 is 12 μm.

In the tab film of the embodiment of the application, the first PP layer 11 and the second PP layer 17 resist the temperature of 140-145 ℃; the first bonding PP layer 12 and the second bonding PP layer 16 resist the temperature of 150-155 ℃; the temperature of the high-temperature resistant middle layer 14 is 260-265 ℃. Therefore, in the tab film of the embodiment of the application, a layered composite structure with gradually improved temperature resistance is formed, and the overall high temperature resistance of the tab film is significantly improved.

In addition, in the tab film of some embodiments, one or more of an antioxidant, a crosslinking agent, and a nucleating agent may be further included in the first PP layer, the first adhesive layer, the high-temperature resistant intermediate layer, the second adhesive PP layer, and the second PP layer. The antioxidant can be an antioxidant BHT (butylated hydroxytoluene), and can delay or inhibit the progress of the oxidation process of the polymer, so that the aging of the tab film is prevented, and the service life of the tab film is prolonged. The antioxidant can also be a peroxide decomposition type antioxidant, a free radical scavenging type antioxidant and a metal deactivation type antioxidant. The cross-linking agent may be a cross-linking agent DCP (Crosslinking agent DCP), which helps to improve the insulation and heat resistance of the glue line. The coupling agent can also be silane, titanate, aluminate, organochromium complex, boride, phosphate, zirconate, stannate and other coupling agents. The nucleating agent can accelerate crystallization rate, increase crystallization density and promote grain size refinement, and achieves the physical and mechanical properties of shortening molding cycle, improving transparency, surface gloss, tensile strength, rigidity, heat distortion temperature, impact resistance, creep resistance and the like of products. The nucleating agent can also be an inorganic nucleating agent, an organic nucleating agent or a high molecular nucleating agent.

Tab

Some embodiments of the present application provide a tab, where the tab includes a metal strip, and tab films are attached to two sides of the metal strip, and the tab films are provided in the embodiments of the present application.

Battery cell

Some embodiments of the present application further provide a battery, where the battery includes an aluminum plastic film and the tab provided by the embodiments of the present application, a metal strap of the tab has a first end located outside the aluminum plastic film and a second end located inside the aluminum plastic film, and the first end of the metal strap is fixedly connected with the aluminum plastic film through the tab film.

Example 1 and comparative examples 1 and 2

The tab film of example 1 was prepared as follows:

(1) Preparing a PP layer-bonding PP layer co-extrusion layer: raw materials of a first PP layer (melt index is 9g/10min of maleic anhydride modified polypropylene resin, the maleic anhydride modified polypropylene resin comprises 90-100 parts by mass of polypropylene resin and 2-10 parts by mass of maleic anhydride) and raw materials of a first bonding PP layer (melt index is 10g/10min of diisobenzene peroxide modified polypropylene resin and black master batch, the diisobenzene peroxide modified polypropylene resin comprises diisobenzene peroxide and polypropylene resin, the mass percentage of the diisobenzene peroxide in the diisobenzene peroxide modified polypropylene resin is 0.5 percent, the black master batch is carbon black, the mass percentage of the carbon black in the second bonding PP layer is 8 percent) are added into a double-die co-extrusion device, and two layers of co-extrusion are carried out according to 50: and (3) performing coextrusion at a thickness ratio of 50 and a total thickness of 42 mu m to obtain a first PP layer-first bonding PP layer coextrusion layer, wherein the thicknesses of the first PP layer and the first bonding PP layer are respectively 21 mu m. The raw materials of the second PP layer (maleic anhydride modified polypropylene resin with the melt index of 9g/10min, wherein the maleic anhydride modified polypropylene resin comprises 90-100 parts by mass of polypropylene resin and 2-10 parts by mass of maleic anhydride) and the raw materials of the second bonding PP layer (diisobenzene peroxide modified polypropylene resin with the melt index of 10g/10min and black master batch, wherein the diisobenzene peroxide modified polypropylene resin comprises diisobenzene peroxide and polypropylene resin, the mass percentage of the diisobenzene peroxide in the diisobenzene peroxide modified polypropylene resin is 0.5 percent, the black master batch is carbon black, and the mass percentage of the carbon black in the second bonding PP layer is 3-10 percent) are added into a double-die co-extrusion device, and the two layers of co-extrusion are carried out according to 50: and (3) performing coextrusion at a thickness ratio of 50 and a total thickness of 42 mu m to obtain a second PP layer-second bonding PP layer coextrusion layer, wherein the thicknesses of the second PP layer and the second bonding PP layer are respectively 21 mu m.

(2) Preparing a first adhesive layer-high temperature resistant intermediate layer-second adhesive layer composite layer: coating raw materials of a first adhesive layer (aqueous polyurethane adhesive) and a second adhesive layer (aqueous polyurethane adhesive) on two surfaces of a high-temperature-resistant intermediate layer (polyethylene terephthalate) respectively to obtain a first adhesive layer-high-temperature-resistant intermediate layer-second adhesive layer composite layer; wherein the thickness of the high temperature resistant intermediate layer is 12 mu m; the thickness of the first adhesive layer and the second adhesive layer was 2 μm, respectively.

(3) Multi-layer compounding: compounding the first PP layer-first bonding PP layer co-extrusion layer on the surface of a first adhesive layer of the first adhesive layer-high temperature resistant middle layer-second adhesive layer composite layer through single-sided lamination, and enabling the first bonding PP layer to be laminated on the surface of the first adhesive layer; and compounding the second PP layer-second bonding PP layer co-extrusion layer on the surface of the second adhesive layer in the first adhesive layer-high temperature resistant middle layer-second adhesive layer composite layer through single-sided lamination, and compounding the second bonding PP layer on the surface of the second adhesive layer to obtain the tab film, wherein the total thickness of the tab film is 100 mu m.

Comparative example 1

The procedure for the preparation of comparative example 1 differs from that of example 1 in that: the tab film prepared in comparative example 1 does not include a high temperature resistant intermediate layer and a second adhesive layer, i.e., the tab film of comparative example 1 includes a first PP layer, a first adhesive layer, a second adhesive PP layer, and a second PP layer in this order.

Comparative example 2

The procedure for the preparation of comparative example 2 differs from that of example 1 in that: in the tab film prepared in comparative example 2, polypropylene resin and black master batch, which were not peroxide-modified, were used as raw materials of the first and second adhesive PP layers.

Performance detection and comparison

The tab films prepared in example 1 and comparative examples 1 to 2 were tested for adhesion performance and heat resistance.

(1) Initial peel strength detection method and detection result:

the detection method comprises the following steps:

the tab films prepared in example 1 and comparative examples 1 to 2 were cut to a width of 10mm, and a nickel tape was attached to a tab film machine, and heated at a high frequency at 200℃for 3 seconds. The initial peel strength was measured according to national standard GB 2792-1998.

Detection result:

example 1: the initial peel strength is greater than 1.8N/mm;

comparative example 1: initial peel strength of 1.6N/mm;

comparative example 2: the initial peel strength was 1.5N/mm.

(2) Temperature resistance detection method and detection result:

the detection method comprises the following steps:

the tab films prepared in example 1 and comparative examples 1 to 2 were immersed in 1000PPM electrolyte at 85 ℃. Taking out at certain intervals, and observing whether layering occurs in the product; and peel strength was measured according to national standard GB 2792-1998.

Detection result:

example 1: no delamination occurred by 1680 hours;

comparative example 1: delamination occurred in 1200 hours;

comparative example 2: delamination occurred for 1000 hours.

The graph of the change in peel strength of tab film as the electrolyte soak time was extended is shown in fig. 3. As can be seen from fig. 3, the tab films of comparative examples 1 and 2 are significantly inferior in temperature resistance to the tab film of example 1.

The above embodiments are only for illustrating the technical solution of the present application, and not for limiting the same; although the application has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the application.

Claims (9)

1. A tab film for applying to both sides of a metal strip of a tab, characterized in that: the tab film comprises a first PP layer, a first bonding PP layer, a first adhesive layer, a high-temperature resistant middle layer, a second adhesive layer, a second bonding PP layer and a second PP layer which are sequentially laminated on the surface of the metal belt;

the first bonding PP layer and the second bonding PP layer both comprise modified polypropylene resin and black master batch, the modified polypropylene resin is peroxide modified polypropylene resin with a melt index of 9-11 g/10min, the peroxide modified polypropylene resin comprises peroxide and polypropylene resin, and the mass percentage of the peroxide in the peroxide modified polypropylene resin is 5-1%; the peroxide is diisobenzene peroxide;

the high temperature resistant interlayer comprises polyethylene terephthalate.

2. The tab film of claim 1 wherein: the thickness of the high-temperature resistant intermediate layer is 10-15 mu m.

3. The tab film of claim 1 wherein: the first PP layer and the second PP layer comprise maleic anhydride modified polypropylene resin with the melt index of 4-7 g/10min, and the thickness of each of the first PP layer and the second PP layer is 20-23 mu m independently.

4. The tab film of claim 1 wherein: in the first or second adhesive PP layer,

the black master batch comprises carbon black, and the mass percentage of the black master batch in the first bonding PP layer or the second bonding PP layer is 3-10%.

5. The tab film of claim 1 wherein: the thickness of the first and second bonding PP layers is 20-23 μm each independently.

6. The tab film of claim 1 wherein: the first adhesive layer and the second adhesive layer each comprise aqueous polyurethane, and the thickness of the first adhesive layer and the second adhesive layer is 1-3 μm independently.

7. The tab film of claim 1 wherein: the temperature resistance of the first PP layer and the second PP layer is 140-145 ℃; the temperature resistance of the first bonding PP layer and the second bonding PP layer is 150-155 ℃; the high-temperature resistant intermediate layer has a temperature resistance of 260-265 ℃.

8. The method for producing tab film according to any one of claims 1 to 7, characterized in that: the method comprises the following steps:

(1) Preparing a PP layer-bonding PP layer co-extrusion layer: adding the raw materials of the first PP layer and the raw materials of the first bonding PP layer into a co-extrusion device, and co-extruding the two layers to obtain a first PP layer-first bonding PP layer co-extrusion layer; adding the raw materials of the second PP layer and the raw materials of the second bonding PP layer into a co-extrusion device, and co-extruding the two layers to obtain a second PP layer-second bonding PP layer co-extrusion layer;

(2) Preparing a first adhesive layer-high temperature resistant intermediate layer-second adhesive layer composite layer: respectively coating the raw materials of the first adhesive layer and the raw materials of the second adhesive layer on two surfaces of the high-temperature resistant intermediate layer to obtain a first adhesive layer-high-temperature resistant intermediate layer-second adhesive layer composite layer;

(3) Multi-layer compounding: compounding the first PP layer-first bonding PP layer co-extrusion layer on the surface of the first adhesive layer-high temperature resistant middle layer-second adhesive layer composite layer, and enabling the first bonding PP layer to be laminated on the surface of the first adhesive layer; and compounding the second PP layer-second bonding PP layer co-extrusion layer on the surface of the second adhesive layer in the first adhesive layer-high temperature resistant middle layer-second adhesive layer composite layer, and compounding the second bonding PP layer on the surface of the second adhesive layer to obtain the tab film.

9. The utility model provides a utmost point ear which characterized in that: the tab comprises a metal strip, tab films are attached to two sides of the metal strip, and the tab films are as claimed in any one of claims 1 to 7.