Battery separator, production method of battery separator and production equipment

Abstract

The present application discloses a production device, a production method and a battery separator, including an extruder, an oven, a composite roller and a stretching roller group. The extruder is used to extrude the separator raw material after melting to obtain a base film. The oven is used to anneal the base film. The composite roller is used to composite the annealed multi-layer base film to form a composite film. The stretching roller group includes a cold drawing section, a hot drawing section and a shaping section, which are used for the composite film to pass through in sequence to stretch the composite film and form a battery separator, the cold drawing section includes a first pressing roller and a cold drawing roller, the hot drawing section includes a second pressing roller and a hot drawing roller, the shaping section includes a third pressing roller and a shaping roller, and at least one of the first pressing roller, the second pressing roller and the third pressing roller uses a heating roller to heat the front and back sides of the composite film evenly. The first pressing roller, the second pressing roller and / or the third pressing roller have a heating function, so that the front and back sides of the composite film are heated evenly during the stretching process, effectively improving the consistency of the battery separator.

Description

Technical Field

[0001] The present application relates to the technical field of battery separators, and in particular to a battery separator, a production method of the battery separator, and a production device. Background Art

[0002] Lithium-ion batteries have good safety, high energy density, and are suitable for large current discharge. They are widely used in digital products, electric bicycles, electric motorcycles, electric vehicles, power storage, communication storage, and other fields. Lithium batteries are mainly composed of four major components, including positive and negative electrodes, separators (diaphragms), and electrolytes. Among them, the lithium battery separator plays the role of isolating the positive and negative electrodes in the battery and conducting ions. It is one of the important components of lithium batteries.

[0003] The consistency of battery separators is one of the important factors in evaluating the quality of battery separators. In actual production, the range determination method is usually used to evaluate the consistency of battery separators. Specifically, in the experiment, the multi-layer battery separators have 3-20 layers, which are stretched together and formed at one time. The air permeability value from one side to the other side of each separator is usually tested, and the air permeability range is finally used to determine the consistency. The range of air permeability between layers of existing battery separators is usually greater than 70S, but with the advancement of technology, the requirements for the consistency of battery separators are getting higher and higher, and the existing battery separators cannot meet the requirements of high consistency. Summary of the invention

[0004] The present application provides a battery separator, a production method of the battery separator and a production device, so as to solve the problem of low consistency of existing battery separators.

[0005] The present application provides a battery separator production device, comprising:

[0006] An extruder, wherein the extruder is used to extrude the diaphragm raw material after melting to obtain a base film;

[0007] An oven, wherein the oven is used to anneal the base film;

[0008] A composite roller, the composite roller is used to composite the annealed multi-layer base film to form a composite film;

[0009] And a stretching roller group, the stretching roller group includes a cold drawing section, a hot drawing section and a shaping section, which are used for allowing the composite film to pass through in sequence to stretch the composite film and form a battery separator, the cold drawing section includes a first pressing roller and a cold drawing roller, a first gap for the composite film to pass through is provided between the first pressing roller and the cold drawing roller, the hot drawing section includes a second pressing roller and a hot drawing roller, a second gap for the composite film to pass through is provided between the second pressing roller and the hot drawing roller, the shaping section includes a third pressing roller and a shaping roller, a third gap for the composite film to pass through is provided between the third pressing roller and the shaping roller, and at least one of the first pressing roller, the second pressing roller and the third pressing roller adopts a heating roller to ensure that the front and back sides of the composite film are heated evenly.

[0010] As a further improvement of the production equipment, the first pressing roller, the second pressing roller and the third pressing roller are all heated rollers, the temperature of the first pressing roller is the same as the temperature of the cold drawing roller, the temperature of the second pressing roller is the same as the temperature of the hot drawing roller, and the temperature of the third pressing roller is the same as the temperature of the shaping roller.

[0011] As a further improvement of the production equipment, the temperature of the first pressing roller and the cold drawing roller are both a, and the value range of a is: 40≤a≤90℃.

[0012] As a further improvement of the production equipment, the temperature of the second pressing roller and the hot drawing roller are both b, and the value range of b is: 130≤b≤155℃.

[0013] As a further improvement of the production equipment, the temperature of the third pressing roller and the shaping roller are both c, and the value range of c is: 150≤c≤170℃.

[0014] As a further improvement of the production equipment, the number of layers of the composite membrane is d, and the value range of d is: 3≤d≤20 layers.

[0015] As a further improvement of the production equipment, the stretching unwinding speed of the stretching roller group is e, and the value range of e is 2≤e≤10m / min.

[0016] As a further improvement of the production equipment, the diaphragm raw material includes at least one of polypropylene, polyethylene, polyacrylonitrile and poly-4-methylpentene.

[0017] The present application provides a method for producing a battery separator, which is applied to the separator production equipment as described in any one of the above items, and the production method comprises:

[0018] Casting extrusion step: the diaphragm raw material is melted and extruded, and then rolled into a long roll of base film;

[0019] Annealing heat treatment step: placing the rolled base film into an oven for baking heat treatment;

[0020] Composite step: composite the annealed base film, composite the multiple layers of base film together to form a composite film roll;

[0021] Stretching step: the composite film is sequentially stretched through a cold drawing section, a hot drawing section and a shaping section to obtain a battery separator, wherein in the cold drawing section, the composite film passes through a first gap between a first pressing roller and a cold drawing roller, in the hot drawing section, the composite film passes through a second gap between a second pressing roller and a hot drawing roller, and in the shaping section, the composite film passes through a third gap between a third pressing roller and a shaping roller, and at least one of the first pressing roller, the second pressing roller and the third pressing roller is a heated roller, so that the front and back sides of the composite film are heated evenly;

[0022] Layering step: Layering the multilayer battery separator prepared by stretching to obtain a single-layer battery separator.

[0023] A battery separator provided in the present application is manufactured using a separator production method as described in any one of the above items, and the interlayer transverse air permeability range of the battery separator is f, and the value range of f is: 20≤f≤60S.

[0024] Beneficial effects of this application:

[0025] The present application provides a production equipment for a battery diaphragm, comprising an extruder, an oven, a composite roller and a stretching roller group. The extruder is used to extrude the diaphragm raw material after melting to obtain a base film. The oven is used to anneal the base film. The composite roller is used to composite the annealed multi-layer base film to form a composite film. The stretching roller group includes a cold drawing section, a hot drawing section and a shaping section, which are used for allowing the composite film to pass through in sequence to stretch the composite film and form a battery diaphragm. The cold drawing section includes a first pressing roller and a cold drawing roller, and there is a first gap between the first pressing roller and the cold drawing roller for the composite film to pass through. The hot drawing section includes a second pressing roller and a hot drawing roller, and there is a second gap between the second pressing roller and the hot drawing roller for the composite film to pass through. The shaping section includes a third pressing roller and a shaping roller, and there is a third gap between the third pressing roller and the shaping roller for the composite film to pass through. At least one of the first pressing roller, the second pressing roller and the third pressing roller uses a heating roller to heat the front and back sides of the composite film evenly. The first pressing roller, the second pressing roller and / or the third pressing roller have a heating function, so that the front and back sides of the composite film are heated evenly during the stretching process, which effectively improves the consistency of the battery separator. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic diagram of the structure of a battery separator production device in one embodiment of the present application.

[0027] Attached figures: 100, cold drawing section; 110, first pressing roller; 120, cold drawing roller; 200, hot drawing section; 210, second pressing roller; 220, hot drawing roller; 300, shaping section; 310, third pressing roller; 320, shaping roller; 400, unwinding section; 500, base film; 600, composite film; 700, battery separator; 800, composite roller. DETAILED DESCRIPTION

[0028] The present application is further described in detail below by specific embodiments in conjunction with the accompanying drawings, wherein similar elements in different embodiments use associated similar element numbers. In the following embodiments, many detailed descriptions are intended to enable the present application to be better understood. However, those skilled in the art can effortlessly recognize that some of the features can be omitted in different situations, or can be replaced by other elements, materials, methods. In some cases, some operations related to the present application are not shown or described in the specification, in order to avoid the core part of the present application being overwhelmed by too much description, and for those skilled in the art, it is not necessary to describe these related operations in detail, and they can fully understand the related operations according to the description in the specification and the general technical knowledge in the art.

[0029] In addition, the features, operations or characteristics described in the specification can be combined in any appropriate manner to form various implementations. At the same time, the steps or actions in the method description can also be interchanged or adjusted in a manner that is obvious to those skilled in the art. Therefore, the various sequences in the specification and the drawings are only for the purpose of clearly describing a certain embodiment and are not meant to be a required sequence, unless otherwise specified that a certain sequence must be followed.

[0030] The serial numbers of the components in this document, such as "first", "second", etc., are only used to distinguish the objects described and do not have any order or technical meaning. The "connection" and "coupling" mentioned in this application, unless otherwise specified, include direct and indirect connections (couplings).

[0031] The current consistency of battery separators is not high enough, and it is increasingly difficult to meet the needs of technological development. In order to improve the consistency of battery separators, the inventors conducted a series of studies and experiments. The inventors found that when stretching the separator, the steel roller needs to be heated, while the pressure roller that cooperates with the steel roller does not have a heating function, which leads to uneven heating on the front and back sides of the separator during the stretching process, affecting the consistency of the product.

[0032] This embodiment provides a battery separator production device.

[0033] Please refer to Figure 1 The production equipment includes an extruder (not shown in the figure), an oven (not shown in the figure), a composite roller 800 and a stretching roller group.

[0034] The extruder is used to extrude the diaphragm raw material after melting to obtain the base film 500. The oven is used to anneal the base film 500. The composite roller 800 is used to composite the annealed multi-layer base film 500 to form a composite film 600. The stretching roller group includes a cold drawing section 100, a hot drawing section 200 and a shaping section 300, which are used for allowing the composite film 600 to pass through in sequence to stretch the composite film 600 and form a battery separator 700. The cold drawing section 100 includes a first pressing roller 110 and a cold drawing roller 120, and a first gap is provided between the first pressing roller 110 and the cold drawing roller 120 for the composite film 600 to pass through. The hot drawing section 200 includes a second pressing roller 210 and a hot drawing roller 220, and a second gap is provided between the second pressing roller 210 and the hot drawing roller 220 for the composite film 600 to pass through. The shaping section 300 includes a third pressing roller 310 and a shaping roller 320, and a third gap is provided between the third pressing roller 310 and the shaping roller 320 for the composite film 600 to pass through. At least one of the first pressing roller 110, the second pressing roller 210 and the third pressing roller 310 uses a heating roller to ensure that the front and back sides of the composite film 600 are heated evenly.

[0035] The first pressing roller 110, the second pressing roller 210 and / or the third pressing roller 310 have a heating function, so that the front and back sides of the composite film 600 are heated evenly during the stretching process, which effectively improves the consistency of the battery separator 700. This improves the quality of the battery separator 700 and improves the safety of the battery separator 700 in lithium battery applications.

[0036] Specifically, the base film 500 can be a polypropylene microporous film, a polyethylene microporous film, or a multilayer composite microporous film composed of polyethylene and polypropylene. The base film 500 has a thickness of 5-30um, a porosity range of 30%-80%, and a pore size range of 0.01-0.15um. The melt index of polypropylene is 0.5-3.5 (g / 10min, 230°C), the weight average molecular weight is 2×105-5.5×105, and the molecular weight distribution is 2-8. The melt index of polyethylene is 0.5-3.0 (g / 10min, 190°C), the weight average molecular weight is 1.1×105-4.5×105, and the molecular weight distribution is 2-6.

[0037] Specifically, the extrusion rate of the diaphragm raw material is 20-100 kg / h, the extrusion temperature is 150-280°C, the die temperature for extrusion is 160-260°C, the casting drawing speed during cast extrusion is 60-150 m / min, and the temperature of the casting roll used is 60-95°C.

[0038] Specifically, during the annealing heat treatment, the rolled base film 500 is put into an oven for baking heat treatment, wherein the baking temperature is 120-160° C. and the baking time is 8-20 hours. The multi-layer battery separator 700 with the same physical and chemical properties and structure is obtained by stretching the composite film 600.

[0039] In actual production, the membranes with different pore structures can be regulated by adjusting the stretching ratio and stretching temperature.

[0040] Please refer to Figure 1 The ratios and temperatures of the cold drawing section 100, the hot drawing section 200, and the shaping section 300 are different, and the temperatures and ratios of the stretching sections are matched. The stretching ratio of each section is achieved by the speed difference between different steel rollers and the partition effect of the pressure roller. The cold drawing roller 120, the hot drawing roller 220, and the shaping roller 320 can use steel rollers.

[0041] Please refer to Figure 1 In one embodiment, the first pressing roller 110, the second pressing roller 210 and the third pressing roller 310 are all heated rollers, the temperature of the first pressing roller 110 is the same as the temperature of the cold drawing roller 120, the temperature of the second pressing roller 210 is the same as the temperature of the hot drawing roller 220, and the temperature of the third pressing roller 310 is the same as the temperature of the shaping roller 320.

[0042] In a more specific embodiment, the heating temperature range of the first pressing roller 110, the second pressing roller 210 and the third pressing roller 310 can reach up to 350°C, and the roller surface temperature accuracy is ±0.5°C. Each pressing roller can control the temperature individually, and the material used is a steel roller with a good heat-conducting rubber roller on the surface. The roller surface temperature of the cold drawing roller 120, the hot drawing roller 220 and the shaping roller 320 can be adjusted individually, and the roller surface temperature deviation is less than 1°C.

[0043] Please refer to Figure 1 In one embodiment, the heating roller is heated by at least one of oil heating, resistance heating, and infrared heating.

[0044] Specifically, the cold drawing ratio is 1.05-1.3, the hot drawing ratio is 1.8-2.3, and the shaping ratio is 0.7-0.95. The temperature of the cold drawing roller / pressing roller is 40-90°C, the temperature of the hot drawing roller / pressing roller is 130-155°C, the temperature of the shaping roller / pressing roller is 150-170°C, and the stretching and unwinding speed is 2m / min-10m / min. The number of stretched film rolls is 3-20 rolls.

[0045] Please refer to Figure 1 In one embodiment, the temperatures of the first pressing roller 110 and the cold drawing roller 120 can be independently controlled. The temperatures of the first pressing roller 110 and the cold drawing roller 120 are both a, and the value range of a is: 40≤a≤90℃.

[0046] Please refer to Figure 1 In one embodiment, the temperatures of the second pressing roller 210 and the hot pulling roller 220 can be individually regulated, and the temperatures of the second pressing roller 210 and the hot pulling roller 220 are both b, and the value range of b is: 130≤b≤155℃.

[0047] Please refer to Figure 1 In one embodiment, the temperatures of the third pressing roller 310 and the shaping roller 320 can be adjusted independently. The temperatures of the third pressing roller 310 and the shaping roller 320 are both c, and the value range of c is: 150≤c≤170℃.

[0048] Please refer to Figure 1 In one embodiment, the number of layers of the composite film 600 is d, and the value range of d is: 3≤d≤20 layers.

[0049] Specifically, in this embodiment, four layers of diaphragms are compounded together, and in other embodiments, five layers, six layers, or other suitable number of layers of diaphragms may be compounded together.

[0050] Please refer to Figure 1 In one embodiment, the production equipment includes an unwinding section 400, and the unwinding section 400 is provided with multiple rolls of base film 500. The base film 500 extends from the unwinding section 400 to be stacked on a composite roller 800, and then composited by the composite roller 800 to form a composite film 600.

[0051] Please refer to Figure 1 In one embodiment, the stretching unwinding speed of the stretching roller group is e, and the value range of e is 2≤e≤10m / min.

[0052] Please refer to Figure 1 In one embodiment, the membrane material includes at least one of polypropylene, polyethylene, polyacrylonitrile and poly-4-methylpentene.

[0053] On the other hand, this embodiment also provides a method for producing a battery separator.

[0054] The production method is applied to the above-mentioned diaphragm production equipment, and the production method comprises:

[0055] Casting extrusion step: the diaphragm raw material is melted and extruded, and then rolled into a long roll of base film;

[0056] Annealing heat treatment step: placing the rolled base film into an oven for baking heat treatment;

[0057] Composite step: composite the annealed base film, composite the multiple layers of base film together to form a composite film roll;

[0058] Stretching step: the composite film is sequentially stretched through a cold drawing section, a hot drawing section and a shaping section to obtain a battery separator, wherein in the cold drawing section, the composite film passes through a first gap between a first pressing roller and a cold drawing roller, in the hot drawing section, the composite film passes through a second gap between a second pressing roller and a hot drawing roller, and in the shaping section, the composite film passes through a third gap between a third pressing roller and a shaping roller, and at least one of the first pressing roller, the second pressing roller and the third pressing roller is a heated roller, so that the front and back sides of the composite film are heated evenly;

[0059] Layering step: Layering the multilayer battery separator prepared by stretching to obtain a single-layer battery separator.

[0060] The above method can produce a single-layer multilayer diaphragm with a porosity distribution of 30%-50% and a thickness of 5-30 um.

[0061] On the other hand, this embodiment also provides a battery separator.

[0062] The battery separator is manufactured by the separator production equipment and production method. The interlayer transverse air permeability range of the battery separator is f, and the value range of f is: 20≤f≤60S.

[0063] On the other hand, this embodiment also provides data of specific embodiments and comparative examples obtained in actual use of production equipment and production methods for some battery separators.

[0064] In one embodiment, the cold-drawing, hot-drawing, and heat-setting rollers of the stretching machine are heated rollers. The thickness of the single layer before stretching is 10 μm, the unwinding speed is 5 m / min, and the number of stretching rolls is 16. The temperature of the cold-drawing roller is 50°C, the temperature of the hot-drawing roller is 150°C, and the temperature of the setting roller is 160°C. The cold-drawing roller is 50°C, the hot-drawing roller is 150°C, and the setting roller is 160°C. The cold-drawing ratio is 1.1, the hot-drawing ratio is 1.9, and the setting ratio is 0.8. After stretching, the diaphragm is layered to obtain a single-layer diaphragm. After the experiment, the test showed that the interlayer air permeability range was 35S.

[0065] In a comparative example, a device without a heated pressure roller (the pressure roller has no heating function) is used for stretching. The single layer thickness before stretching is 10μm, the unwinding speed is 5m / min, and the number of stretched rolls is 16 rolls. The temperature of the cold drawing roller is 50℃, the temperature of the hot drawing roller is 150℃, and the temperature of the shaping roller is 160℃; the cold drawing roller, the hot drawing roller, and the shaping roller are all rollers without heating function; the cold drawing ratio is 1.1, the hot drawing ratio is 1.9, and the shaping ratio is 0.8. After stretching, the diaphragm is layered to obtain a single-layer diaphragm. After the experiment, the test showed that the interlayer air permeability value range was 90S.

[0066] In one embodiment, the cold-drawing, hot-drawing, and heat-setting rollers of the stretching machine are heated rollers. The single-layer thickness before stretching is 10 μm, the unwinding speed is 5 m / min, and the number of stretching rolls is 16. The temperature of the cold-drawing roller is 60°C, the temperature of the hot-drawing roller is 155°C, and the temperature of the setting roller is 162°C. The cold-drawing roller is 60°C, the hot-drawing roller is 155°C, and the setting roller is 162°C. The cold-drawing ratio is 1.1, the hot-drawing ratio is 1.9, and the setting ratio is 0.8. After stretching, the diaphragm is layered to obtain a single-layer diaphragm. After the experiment, the test showed that the interlayer air permeability value range was 28S.

[0067] In a comparative example, a device without a heated pressure roller (the pressure roller has no heating function) is used for stretching. The single layer thickness before stretching is 10μm, the unwinding speed is 5m / min, and the number of stretched rolls is 16 rolls. The temperature of the cold drawing roller is 60°C, the temperature of the hot drawing roller is 155°C, and the temperature of the shaping roller is 162°C. The cold drawing roller, the hot drawing roller, and the shaping roller are all rollers without heating function. The cold drawing ratio is 1.1, the hot drawing ratio is 1.9, and the shaping ratio is 0.8. After stretching, the diaphragm is layered to obtain a single-layer diaphragm. After the experiment, the test showed that the interlayer air permeability value range was 70S.

[0068] In one embodiment, the cold-drawing, hot-drawing, and heat-setting rollers of the stretching machine are heated rollers. The thickness of the single layer before stretching is 10 μm, the unwinding speed is 5 m / min, and the number of stretching rolls is 16. The temperature of the cold-drawing roller is 80°C, the temperature of the hot-drawing roller is 155°C, and the temperature of the setting roller is 162°C. The cold-drawing roller is 80°C, the hot-drawing roller is 155°C, and the setting roller is 162°C. The cold-drawing ratio is 1.1, the hot-drawing ratio is 1.9, and the setting ratio is 0.8. After stretching, the diaphragm is layered to obtain a single-layer diaphragm. After the experiment, the interlayer air permeability value range was 37S.

[0069] In a comparative example, a device without a heated pressure roller (the pressure roller has no heating function) is used for stretching. The single layer thickness before stretching is 10μm, the unwinding speed is 5m / min, and the number of stretched rolls is 16 rolls. The temperature of the cold drawing roller is 80°C, the temperature of the hot drawing roller is 155°C, and the temperature of the shaping roller is 162°C. The cold drawing roller, the hot drawing roller, and the shaping roller are all rollers without heating function. The cold drawing ratio is 1.1, the hot drawing ratio is 1.9, and the shaping ratio is 0.8. After stretching, the diaphragm is layered to obtain a single-layer diaphragm. After the experiment, the test showed that the interlayer air permeability value range was 110S.

[0070] The above contents are further detailed descriptions of the present application in combination with specific implementation methods, and it cannot be determined that the specific implementation of the present application is limited to these descriptions. For ordinary technicians in the technical field to which the present application belongs, several simple deductions or substitutions can be made without departing from the inventive concept of the present application.

Claims

1. A battery separator production device, characterized in that: include: An extruder, wherein the extruder is used to extrude the diaphragm raw material after melting to obtain a base film; An oven, wherein the oven is used to anneal the base film; A composite roller, the composite roller is used to composite the annealed multi-layer base film to form a composite film; and a stretching roller group, the stretching roller group includes a cold drawing section, a hot drawing section and a shaping section, and is used for allowing the composite film to pass through in sequence to stretch the composite film and form a battery separator, the cold drawing section includes a first pressing roller and a cold drawing roller, a first gap for the composite film to pass through is provided between the first pressing roller and the cold drawing roller, the hot drawing section includes a second pressing roller and a hot drawing roller, a second gap for the composite film to pass through is provided between the second pressing roller and the hot drawing roller, the shaping section includes a third pressing roller and a shaping roller, a third gap for the composite film to pass through is provided between the third pressing roller and the shaping roller, and at least one of the first pressing roller, the second pressing roller and the third pressing roller adopts a heating roller, so that the front and back sides of the composite film are heated evenly; The first pressing roller, the second pressing roller and the third pressing roller are all heated rollers, the temperature of the first pressing roller is the same as the temperature of the cold drawing roller, the temperature of the second pressing roller is the same as the temperature of the hot drawing roller, and the temperature of the third pressing roller is the same as the temperature of the shaping roller; the temperature of the first pressing roller and the cold drawing roller is a, and the value range of a is: 40≤a≤90℃; the temperature of the second pressing roller and the hot drawing roller is b, and the value range of b is: 130≤b≤155℃; the temperature of the third pressing roller and the shaping roller is c, and the value range of c is: 150≤c≤170℃; The first pressing roller, the second pressing roller and the third pressing roller can all be individually temperature controlled.

2. The production equipment according to claim 1, characterized in that The number of layers of the composite film is d, and the value range of d is: 3≤d≤20 layers.

3. The production equipment according to claim 1, characterized in that The stretching unwinding speed of the stretching roller group is e, and the value range of e is 2≤e≤10m / min.

4. The production equipment according to claim 1, characterized in that The membrane material includes at least one of polypropylene, polyethylene, polyacrylonitrile and poly-4-methylpentene.

5. A method for producing a battery separator, characterized in that: Applied to the diaphragm production equipment according to any one of claims 1 to 4, the production method comprises: Casting extrusion step: the diaphragm raw material is melted and extruded, and then rolled into a long roll of base film; Annealing heat treatment step: placing the rolled base film into an oven for baking heat treatment; Composite step: composite the annealed base film, composite the multiple layers of base film together to form a composite film roll; Stretching step: the composite film is sequentially stretched through a cold drawing section, a hot drawing section and a shaping section to obtain a battery separator, wherein in the cold drawing section, the composite film passes through a first gap between a first pressing roller and a cold drawing roller, in the hot drawing section, the composite film passes through a second gap between a second pressing roller and a hot drawing roller, and in the shaping section, the composite film passes through a third gap between a third pressing roller and a shaping roller, and at least one of the first pressing roller, the second pressing roller and the third pressing roller is a heated roller, so that the front and back sides of the composite film are heated evenly; Layering step: Layering the multilayer battery separator prepared by stretching to obtain a single-layer battery separator.

6. A battery separator, characterized in that: The battery separator is manufactured using the separator production method as claimed in claim 5, wherein the interlayer transverse air permeability range of the battery separator is f, and the value range of f is: 20≤f≤60S.

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