CN112768844B - Long-lasting tab and application - Google Patents

Abstract

The invention provides a long-lasting pole lug and application thereof. The crosslinked polyethylene in the invention has very good thermal stability, electrolyte corrosion resistance and electrochemical stability, the three-dimensional reticular molecular chain structure in the crosslinked polyethylene layer can inhibit the swelling of an organic solvent in the electrolyte to a bonding part, and can prevent the over-sealing of tab glue during the packaging of the tab, prevent the contact of a nickel tab and an aluminum layer, reduce the risk of electrochemical corrosion, thereby improving the packaging reliability of the tab and an aluminum plastic film, and the long-term use reliability and service life of the battery.

Description

Long-lasting lugs and applications

technical field

The invention belongs to the field of lithium ion batteries, and in particular relates to a long-durable tab and its application.

Background technique

As one of the important types of lithium-ion batteries, the pouch battery is made of aluminum-plastic film materials and rubber strips in polymer tabs, which are fused to each other under a certain hot-pressing process to achieve a sealing effect. Compared with hard-shell battery packaging, it has the following advantages: 1. Since the aluminum-plastic film material is lighter in weight, it is at least 30% lighter than hard-shell batteries, so under the same capacity condition, the specific energy is higher; 2. Generally Due to the relatively low heat seal strength of the aluminum-plastic film and the tabs, when the battery is thermally out of control, it will mainly bulge and crack instead of explode, so the safety performance is high; 3. The internal resistance is small, which is conducive to reducing the battery's working output. heat and increase battery power.

The aluminum-plastic film in the pouch battery is generally composed of three layers, including: 1. The outermost nylon layer, which can improve the corrosion resistance and good thermoplasticity of the aluminum-plastic film; 2. The aluminum layer in the middle layer , It isolates impurities such as moisture and oxygen from entering the battery, and at the same time has a certain mechanical strength; 3. The innermost polypropylene layer, which can isolate the contact between the electrolyte and the aluminum layer, and has resistance to electrolyte corrosion. Tabs are generally composed of nickel-plated copper or aluminum metal sheets and films. When packaging, the aluminum-plastic film is folded in half so that the polypropylene layer and the tab film are docked. During the heat-sealing process, under a certain temperature (>180°C), heat-sealing pressure and heat-sealing time, the aluminum-plastic film polypropylene layer and the The ear rubber strips are mixed together, and after a certain period of time, they are fused with each other and cooled, and finally achieve the sealing effect. However, once the heat sealing process is not well controlled, over-sealing may occur, making the nickel tab contact with the aluminum layer, and electrochemical corrosion may occur, which may lead to damage to the aluminum layer, and eventually cause liquid leakage, bloating, etc. Serious failure problem.

As the energy density of lithium-ion batteries increases, higher requirements are put forward for the reliability and durability of tabs and aluminum-plastic film packaging. The mutual melting and bonding effect between the polymer tab film layer and the aluminum-plastic film polypropylene will greatly affect the reliability of the packaging structure and the long-term service life of the battery.

Therefore, the development of long-durable tabs suitable for high-energy-density lithium-ion batteries is one of the important foundations for power lithium-ion batteries.

Contents of the invention

In view of this, the object of the present invention is to provide a long-lasting tab for high energy density lithium-ion batteries, which is conducive to improving the service life of the tab, the reliability of the package structure of the tab and aluminum-plastic film, and the long-term use of the battery reliability and longevity.

In order to achieve the above object, technical solution of the present invention is achieved in that way:

The long-lasting tab includes a tab body, a cross-linked polyethylene layer, and a tab adhesive layer. The cross-linked polyethylene layer is bonded to the surface of the tab body, and the tab adhesive layer is bonded to the cross-linked The surface of the polyethylene layer.

Preferably, the cross-linked polyethylene layer is prepared from polyethylene through radiation cross-linking or silicone cross-linking.

Preferably, said radiation crosslinking comprises the steps of:

a. Polyethylene with a weight-average molecular weight of 10kg/mol-900kg/mol is extruded and cast in a twin-screw extruder, and a polyethylene film with a thickness of 0.5mm-3mm is obtained by casting, and the casting temperature is 200°C ～250℃, cooling roll temperature is 20℃～55℃, extrusion speed is 0.1m/min～20m/min, cooling roller speed is 5r/min～300r/min;

b. The polyethylene film is subjected to longitudinal stretching treatment at high temperature, wherein the longitudinal stretching temperature is 70°C-130°C, the longitudinal stretch ratio is 2-20, and a polyethylene film with a thickness of 3-200 μm is obtained;

c. The polyethylene film obtained after stretching is irradiated with high-energy rays at room temperature. The irradiation intensity is 20Gy/min-200Gy/min, and the total dose is 30kGy-250kGy. During the irradiation process, it needs to be kept sealed. State, the purpose is to prevent excessive cross-linking of polyethylene;

d. The irradiated polyethylene film is placed in an oven at a temperature range of 40°C to 110°C, and left to stand for 0.5h to 24h;

e. The polyethylene film after the high temperature treatment is left to stand for a period of time at room temperature to obtain a cross-linked polyethylene layer, and the standing time is 0.5h to 24h.

Preferably, in step a, the weight-average molecular weight of polyethylene is 20kg/mol-800kg/mol, the thickness of the polyethylene casting film is 0.5mm-1.5mm, the casting temperature is 210°C-230°C, and the cooling roll temperature is 30 ℃～50℃, the extrusion rate is 0.1m/min～15m/min, the cooling roll speed is 5r/min～180r/min; preferably, in step b, wherein the longitudinal stretching temperature is 90℃～130℃, the longitudinal The stretch ratio is 2-15, and the thickness of the obtained polyethylene film is 5-150 μm; preferably, in step c, the irradiation intensity is 50Gy/min-150Gy/min, and the total dose is 40kGy-250Gy, preferably, step In d, the temperature range is 50°C-90°C, and the treatment time is 0.5h-10h. Preferably, in step e, the standing time at room temperature is 0.5h-10h.

Preferably, the siloxane crosslinking comprises the steps of:

(1) In the twin-screw extrusion with an aspect ratio of 30 or more, put 100 parts of polyethylene, 0.1 to 0.3 parts of initiator, 0.1 to 1.2 parts of siloxane grafting agent, and 0.4 to 1.0 parts of catalyst through the metering hopper to put the corresponding materials Cross-linking after adding to the extruder, the cross-linking temperature is 110 ° C ~ 180 ° C;;

(2) Extrude and cast cross-linked polyethylene film through an extruder, the casting temperature is 200°C-250°C, the temperature of the cooling roll is 20°C-55°C, and the extrusion rate is 0.1m/min-20m/min, Cooling roll speed is 5r/min～300r/min;

(3) The cross-linked polyethylene film is longitudinally stretched at high temperature, wherein the longitudinal stretching temperature is 70°C-130°C, and the longitudinal stretching ratio is 2-15. After cooling and shaping, high-strength and high-resistance polyethylene strips are obtained.

Preferably, in step (1), the number of polyethylene is 100 parts, the initiator is 0.1-0.2 parts, the siloxane crosslinking agent is 0.3-0.9 parts, the catalyst is 0.4-0.6 parts, and the cross-linking temperature is 120°C ~160°C, where the initiators are dicumyl peroxide (DCP), dibenzoyl peroxide (BPO), tert-butyl peroxybenzoate (TBPO), di-tert-butyl peroxide, di-tert-peroxide At least one of butyl, the siloxane grafting agent is at least one of vinyltrimethoxysilane, methacryloxypropyltrimethoxysilane, and the catalyst is dimethyltin dilaurate, At least one of dioctyltin dilaurate and bismuth neodecanoate; preferably, in step (2), the polyethylene film thickness is 0.5mm～1.5mm, the casting temperature is 210°C～230°C, and the cooling roll temperature is 30°C to 50°C, the extrusion rate is 0.1m/min to 15m/min, the cooling roll speed is 5r/min to 180r/min; preferably, in step (3), the longitudinal stretching temperature is 90°C to 130 °C, the longitudinal stretch ratio is 2-12.

The second object of the present invention is to provide a long-durable tab preparation method, comprising the following steps:

Step 1: Place a layer of cross-linked polyethylene on the nickel-plated copper lug or aluminum sheet, with a gel content of 7.5% to 90% and a thickness of 3 μm to 100 μm; Prepared by cross-linking or siloxane cross-linking preparation method;

Step 2: Bond the cross-linked polyethylene layer on the metal sheet by hot pressing or heat fusion, wherein the hot pressing or heat fusion temperature is 160°C-240°C, and the time is 4-10s, and the cross-linked polyethylene layer must be 0mm~5mm wider than the ear glue layer;

Step 3: Adhesive the tab strips to the cross-linked polyethylene strips by means of hot pressing or thermal fusion, wherein the hot pressing or thermal fusion temperature is 160°C to 240°C, and the time is 4 to 10s. The width of the adhesive layer is 0-5mm smaller than the width of the cross-linked polyethylene layer;

Step 4: Cold-pressing the ears for a period of time, wherein the cold-pressing temperature is 80°C-125°C, and the time is 4-10s.

Preferably, in step 1, the cross-linked polyethylene has a gel content of 12.5% to 85%, and a thickness of 3 μm to 50 μm; preferably, in step 2, the hot pressing or thermal fusion temperature is 180°C to 230°C, and the time is 5-8s, wherein the cross-linked polyethylene layer is 0.5mm-4mm wider than the ear glue layer; preferably, in step 3, the hot-pressing or hot-melting temperature is 180°C-230°C, and the time is 5-8s; preferably , in step 4, the cold pressing temperature is 90°C-120°C, and the time is 5-8s.

The third object of the present invention is to provide a ternary soft-pack battery prepared by using long-durable tabs, including a positive electrode, a negative electrode, a separator and an electrolyte, and the capacity of the battery cell is 3Ah-250Ah.

Compared with the prior art, the long-durable tab of the present invention has the following advantages:

In the invention, a layer of cross-linked polyethylene sheet is thermally pressed or thermally fused on the nickel-plated copper or aluminum sheet, and then a layer of ear glue is thermally pressed or thermally fused on the cross-linked polyethylene layer. The hot-pressed or thermally fused cross-linked polyethylene in the tab of the present invention has very good thermal stability, electrolyte corrosion resistance and electrochemical stability, and the three-dimensional network molecular chain structure in the cross-linked polyethylene layer will not only inhibit electrolysis The organic solvent in the liquid can swell the cross-linked polyethylene layer, and it can prevent the tab glue from being over-sealed when the tab is packaged, prevent the contact between the nickel tab and the aluminum layer, and reduce the risk of electrochemical corrosion, thereby improving the tab It is packaged with aluminum-plastic film for reliability, long-term battery reliability and service life.

Specific principle analysis:

The cross-linked polyethylene strip has a three-dimensional network structure (as shown in formula I, formula II and formula III). There are chemical bridging chains between the molecular chains of cross-linked polyethylene. When the temperature rises, the bridging chains between the molecular chains can restrict the movement of the molecular chains, thereby significantly improving its temperature resistance and electrolyte resistance. corrosive. Compared with linear polyethylene, cross-linked polyethylene has the following advantages: (1) The three-dimensional network molecular chain structure makes cross-linked polyethylene have very good heat resistance, high electrolytic corrosion resistance and long service life , its long-term use temperature is around 90°C, and its service life is more than 30 years; (2) more excellent insulation and electrochemical stability; (3) bridging chains between molecular chains in the three-dimensional network structure of cross-linked polyethylene It has strong acid and alkali resistance and electrolyte resistance. Adding a cross-linked polyethylene layer in the tab can significantly improve the electrolyte aging resistance and service life of the tab, the structural reliability of the tab and aluminum-plastic film packaging, and the long-term reliability and life of the battery. Improve the long-term use stability of the diaphragm sex.

Ordinary lug glue polypropylene layer has a melting point of 160°C. Our cell packaging temperature is about 185°C. Especially when the packaging head just heats up, the temperature may be too high. The polypropylene layer will melt obviously and small bubbles will appear, that is caused by overmelting. However, the cross-linked polyethylene cross-network structure of the present invention only becomes soft and does not shrink significantly when the temperature reaches 200°C to 300°C, thus greatly reducing the risk of over-melting.

Description of drawings

In order to illustrate the embodiment of the present invention or the prior art solution more clearly, the accompanying drawings required for the description of the embodiments or the prior art will be briefly described below. The accompanying drawings in the following description are only embodiments of the present invention. Those of ordinary skill in the art can also obtain other drawings based on the provided drawings without creative labor.

Figure 1 is a schematic diagram of the long-durable tab;

Fig. 2 is a data graph showing the variation of the peeling force with the increase of aging time after the tabs are aged in high-temperature soaked electrolyte in Examples 1-3 and Comparative Example 1;

Fig. 3 is a graph showing the changes in tab peeling force with aging time after the application of Examples 4-6 and Comparative Example 2 to lithium-ion batteries at 85°C and 100% SOC storage for 28 days, 56 days, and 84 days.

Explanation of reference signs:

a. Tab body; 2. Cross-linked polyethylene layer; 3. Tab glue layer.

Detailed ways

Unless otherwise defined, the technical terms used in the following embodiments have the same meaning as commonly understood by those skilled in the art to which the present invention belongs. The test reagents used in the following examples, unless otherwise specified, are conventional biochemical reagents; the experimental methods, unless otherwise specified, are conventional methods.

The present invention will be described in detail below in conjunction with the embodiments and accompanying drawings.

Example 1

The preparation method of cross-linked polyethylene rubber strips by irradiation cross-linking in this example: (1) polyethylene with a weight-average molecular weight of 80 kg/mol is extruded and cast in a twin-screw extruder, and the thickness obtained by casting is 0.8mm Polyethylene film, wherein the casting temperature is 230 ° C, the temperature of the cooling roll is 40 ° C, the extrusion rate is 1m/min, and the speed of the cooling roll is 60r/min; (2) The polyethylene film is stretched longitudinally at high temperature Treatment, wherein the stretching temperature is 100°C, the longitudinal (MD) stretch ratio is 10, and the thickness of the polyethylene film is 20 μm. (3) The polyethylene film obtained after stretching is irradiated with high-energy rays at room temperature , the irradiation intensity is 50Gy/min, the total dose is 100kGy, and the sealing state needs to be kept during the irradiation process to prevent excessive cross-linking of polyethylene; (4) the polyethylene film after irradiation is placed in an oven, the temperature The range is 85°C, and the static treatment is for 2 hours; (5) After the static treatment at room temperature for 4 hours, a cross-linked polyethylene strip with a thickness of 20 μm is obtained, and the gel content is 35.1%.

Preparation method of long-durable tabs: (1) Place a layer of cross-linked polyethylene strips flat on the nickel-plated copper tabs, with a gel content of 35.1% and a thickness of 20 μm; The polythene adhesive tape is bonded on the metal sheet, wherein the temperature of hot pressing or heat fusion is 210°C, and the time is 8s. (3) The tab glue is bonded to the polyethylene strip by hot pressing, wherein the hot pressing or thermal fusion temperature is 21°C, the time is 8s, and the width of the cross-linked polyethylene layer is 2mm wider than the tab glue; (4) Cold-pressing the tabs, wherein the cold-pressing temperature is 100° C. and the time is 8 s.

Example 2

In the present embodiment, crosslinked polyethylene rubber strip siloxane crosslinking preparation method: (1) pass polyethylene (100 parts), initiator dicumyl peroxide ( 0.1 part), siloxane grafting agent methacryloxypropyltrimethoxysilane (0.3 part), catalyst dilaurin dimethyl tin (0.5 part) after the metering hopper puts the corresponding materials into the extruder, The cross-linking temperature is 160°C; (2) Extrude and cast cross-linked polyethylene film through the extruder, the casting temperature is 220°C, the cooling roll temperature is 40°C, the extrusion speed is 1m/min～, the cooling roll speed (3) The cross-linked polyethylene film is stretched longitudinally at high temperature, wherein the longitudinal stretching temperature is 120°C, the longitudinal stretch ratio is 9, and the cross-linked polyethylene film with a thickness of 20 μm is obtained after cooling and setting. Vinyl strips with a gel content of 45.4%. Other conditions are the same as in Example 1.

Example 3

The preparation method of cross-linked polyethylene rubber strips by irradiation and crosslinking in this example: the total amount of radiation crosslinking is 155 kGy, the gel content of the obtained radiation cross-linked polyethylene strips is 55.6%, and other conditions are consistent with those in Example 1 .

Example 4

In this embodiment, the gel content of the irradiated cross-linked polyethylene strip is 35.1%, and the other conditions are kept the same as in Example 1.

Preparation of batteries: the batteries prepared in the examples of the present invention and comparative examples are all soft pack batteries, wherein the positive pole is ternary nickel cobalt lithium manganese oxide (NCM622), the negative pole is graphite, the battery capacity is 51Ah, and the cut-off voltage is 2.75V -4.25V. The pole piece of the battery cell is obtained through homogenization, coating, rolling, slitting, punching and other processes. Encapsulation, standing, formation and volume separation complete the preparation of the pouch battery.

High-temperature storage experiment: fully charge the divided cells, store them at 85°C for 28 days, 56 days, and 84 days, then disassemble the stored cells, and test the tab peeling force.

Example 5

In this embodiment, the gel content of the cross-linked polyethylene rubber strip prepared by siloxane cross-linking is 45.4%, and other conditions are kept the same as in Embodiment 4.

Example 6

The gel content of the cross-linked polyethylene strip prepared by irradiation cross-linking in this example is 55.6%, and the others are consistent with Example 4

Comparative example 1

In this embodiment, there is no first layer of cross-linked polyethylene tape in the tab, and the others are consistent with Embodiment 1.

Comparative example 2

In this embodiment, there is no first layer of cross-linked polyethylene tape in the tab, and the others are consistent with Embodiment 4.

As shown in Figure 1, it is a long-lasting tab schematic diagram obtained by the present invention, wherein a is the pole piece body (nickel-plated copper); b is a cross-linked polyethylene layer, which is bonded on the metal sheet by hot pressing, Its width is 2mm wider than that of the tab glue, and the three-dimensional network structure in the cross-linked polyethylene strip makes its resistance to electrolyte swelling, heat resistance and electrochemical stability significantly improved, and it can prevent the tab glue from being overwhelmed when the tab is packaged. Sealing prevents the contact between the nickel tab and the aluminum layer, reduces the risk of electrochemical corrosion, thereby improving the reliability of the tab and the aluminum-plastic film package, and the long-term reliability and life of the battery. Layer c is the ear glue layer, which is bonded to the cross-linked polyethylene layer by hot pressing.

As shown in Figure 2, it can be seen from the variation curves of the tab peeling force after the tabs of Examples 1-3 and Comparative Example 1 are soaked in high temperature and electrolytic aging, when the tabs are bonded with the first layer of cross-linked polyethylene strips, with The aging days of the tabs soaked in high temperature (85°C) soaked in the electrolyte increased (electrolyte + 1000ppm water), and the peeling force of the tabs showed a weak downward trend. In addition, as the gel content of the first layer of cross-linked polyethylene tape increases, the tendency of the tab peel force to decrease becomes weaker. This is because as the gel content of cross-linked polyethylene increases, the cross-linking point density of the three-dimensional network structure increases significantly, so the mutual movement between molecular chains will be more restricted, thereby making the tab bonding resistant to electrolyte swelling , The aging performance is obviously enhanced, so that the downward trend of the tab peeling force is weakened.

As shown in Figure 3, after the application of Examples 4-6 and Comparative Example 2 to lithium-ion batteries at 85°C and 100% SOC storage for 28 days, 56 days, and 84 days, the change data of the tab peeling force obtained by disassembly can be known. When the tabs are bonded with the first layer of cross-linked polyethylene strips, as the high-temperature storage time increases, the tabs have a weak tendency to decrease after disassembly, but the magnitude of the decrease is very small, which shows that at this time The reliability of the package at the tab is still very good, and it has obvious long-term durability. This is because the three-dimensional network molecular chains in cross-linked polyethylene will significantly improve the electrochemical stability of cross-linked polyethylene, which is beneficial to prevent oxidation and maintain structural stability of tab bonding in high voltage and electrolyte environments. Therefore, it is beneficial to improve the reliability and service life of the connection at the tab.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of the present invention. within the scope of protection.

Claims (16)

1. Long and durable tab, characterized in that it includes a tab body, a cross-linked polyethylene layer, and a tab glue layer, the cross-linked polyethylene layer is bonded to the surface of the tab body, and the tab glue The layer is bonded to the surface of the cross-linked polyethylene layer; The preparation method of the long-durable tab comprises the following steps: Step 1: Place a layer of cross-linked polyethylene on the nickel-plated copper lug or aluminum sheet, with a gel content of 7.5% to 90% and a thickness of 3 μm to 100 μm; the cross-linked polyethylene layer is made of polyethylene Prepared by irradiation crosslinking or silicone crosslinking; Step 2: Bond the cross-linked polyethylene layer on the metal sheet by hot pressing or heat fusion, wherein the hot pressing or heat fusion temperature is 160°C-240°C, and the time is 4-10s, and the cross-linked polyethylene layer must be 0mm~5mm wider than the ear glue layer; Step 3: Adhesive the tab strips to the cross-linked polyethylene strips by means of hot pressing or thermal fusion, wherein the hot pressing or thermal fusion temperature is 160°C to 240°C, and the time is 4 to 10s. The width of the adhesive layer is 0-5mm smaller than the width of the cross-linked polyethylene layer; Step 4: Cold-pressing the ears for a period of time, wherein the cold-pressing temperature is 80°C-125°C, and the time is 4-10s. 2. The long-durable tab according to claim 1, characterized in that: said irradiation crosslinking comprises the following steps: a. Polyethylene with a weight-average molecular weight of 10kg/mol-900kg/mol is extruded and cast in a twin-screw extruder, and a polyethylene film with a thickness of 0.5mm-3mm is obtained by casting, and the casting temperature is 200°C ～250℃, cooling roll temperature is 20℃～55℃, extrusion speed is 0.1m/min～20m/min, cooling roller speed is 5r/min～300r/min; b. The polyethylene film is subjected to longitudinal stretching treatment at high temperature, wherein the longitudinal stretching temperature is 70°C-130°C, the longitudinal stretch ratio is 2-20, and a polyethylene film with a thickness of 3-200 μm is obtained; c. The polyethylene film obtained after stretching is irradiated with high-energy rays at room temperature. The irradiation intensity is 20Gy/min-200Gy/min, and the total dose is 30kGy-250kGy. During the irradiation process, it needs to be kept sealed. State, the purpose is to prevent excessive cross-linking of polyethylene; d. The irradiated polyethylene film is placed in an oven at a temperature range of 40°C to 110°C, and left to stand for 0.5h to 24h; e. The polyethylene film after the high temperature treatment is left to stand for a period of time at room temperature to obtain a cross-linked polyethylene layer, and the standing time is 0.5h to 24h. 3. The long-durable tab according to claim 2, characterized in that: in step a, the weight-average molecular weight of polyethylene is 20kg/mol-800kg/mol, and the thickness of the polyethylene cast film is 0.5mm-1.5mm, The casting temperature is 210°C-230°C, the cooling roll temperature is 30°C-50°C, the extrusion speed is 0.1m/min-15m/min, and the cooling roll speed is 5r/min-180r/min. 4. The long-durable tab according to claim 3, characterized in that in step b, wherein the longitudinal stretching temperature is 90°C-130°C, the longitudinal stretching ratio is 2-15, and the thickness of the obtained polyethylene film is 5 to 150 μm. 5. The long-durable tab according to claim 4, characterized in that in step c, the irradiation intensity is 50Gy/min-150Gy/min, and the total dose is 40kGy-250Gy. 6. The long-durable tab according to claim 5, characterized in that in step d, the temperature range is 50°C-90°C, and the treatment time is 0.5h-10h. 7. The long-durable tab according to claim 6, characterized in that in step e, the time for standing at room temperature is 0.5h-10h. 8. The long-durable tab according to claim 1, characterized in that: said siloxane crosslinking comprises the following steps: (1) In the twin-screw extrusion with an aspect ratio of 30 or more, put 100 parts of polyethylene, 0.1 to 0.3 parts of initiator, 0.1 to 1.2 parts of siloxane grafting agent, and 0.4 to 1.0 parts of catalyst through the metering hopper to put the corresponding materials After adding to the extruder, carry out cross-linking, and the cross-linking temperature is 110 ° C ~ 180 ° C; (2) Extrude and cast cross-linked polyethylene film through an extruder, the casting temperature is 200°C-250°C, the temperature of the cooling roll is 20°C-55°C, and the extrusion rate is 0.1m/min-20m/min, Cooling roll speed is 5r/min～300r/min; (3) The cross-linked polyethylene film is longitudinally stretched at high temperature, wherein the longitudinal stretching temperature is 70°C-130°C, and the longitudinal stretching ratio is 2-15. After cooling and shaping, high-strength and high-resistance polyethylene strips are obtained. 9. The long-durable tab according to claim 8, characterized in that: in step (1), the number of polyethylene is 100 parts, the initiator is 0.1-0.2 parts, and the silicone cross-linking agent is 0.3-0.9 parts Parts, 0.4~0.6 parts of catalyst, crosslinking temperature 120 ℃ ~ 160 ℃, wherein the initiator is dicumyl peroxide (DCP), dibenzoyl peroxide (BPO), tert-butyl peroxybenzoate At least one of (TBPO), di-tert-butyl peroxide, and di-tert-butyl peroxide, the siloxane grafting agent is vinyltrimethoxysilane, methacryloxypropyltrimethoxysilane The catalyst is at least one of dimethyltin dilaurate, dioctyltin dilaurate and bismuth neodecanoate. 10. The long-durable tab according to claim 9, characterized in that: in step (2), the thickness of the polyethylene film is 0.5mm-1.5mm, the casting temperature is 210°C-230°C, and the temperature of the cooling roll is 30°C ~50°C, the extrusion rate is 0.1m/min~15m/min, the cooling roll speed is 5r/min~180r/min. 11. The long and durable tab according to claim 10, characterized in that in step (3), wherein the longitudinal stretching temperature is 90°C-130°C, and the longitudinal stretching ratio is 2-12. 12. The long-durable tab according to claim 1, characterized in that in step 1, the cross-linked polyethylene has a gel content of 12.5% to 85% and a thickness of 3 μm to 50 μm. 13. The long-durable tab according to claim 12, characterized in that in step 2, the hot pressing or thermal fusion temperature is 180°C-230°C, and the time is 5-8s, wherein the cross-linked polyethylene layer is longer than the pole. The ear gel layer is 0.5mm to 4mm wide. 14. The long-durable tab according to claim 13, characterized in that in step 3, the temperature of hot pressing or hot fusion is 180°C-230°C, and the time is 5-8s. 15. The long-durable tab according to claim 14, characterized in that in step 4, the cold pressing temperature is 90°C-120°C, and the time is 5-8s. 16. The ternary soft-pack battery prepared by using the long-durable tab according to any one of claims 1-15, characterized in that it includes a positive electrode, a negative electrode, a separator and an electrolyte, and the capacity of the battery cell is 3Ah-250Ah.

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