Battery separator and preparation method thereof, battery and electrical equipment

Abstract

The present application discloses a battery separator and a preparation method, a battery, and an electrical device. The battery separator includes a base film, a first adhesive layer located on one side of the base film, and a heat-resistant layer and a second adhesive layer located on the other side of the base film; the first adhesive layer has a first thickness H1μm, the base film has a first coverage C1%, the heat-resistant layer has a second thickness H2μm, the second adhesive layer has a third thickness H3μm, and the heat-resistant layer has a second coverage C2%, satisfying: H2>H1+H3, C2=(0.6~1.2)*(H1+H3) / H2%, and C1=(0.1~0.3)*H2 / H1%. The present application sets an asymmetric separator structure so that the battery separator has excellent heat resistance and improves the overall safety of the battery. In addition, in the process of compounding the separator and the pole piece, the bonding requirements are met after passing through the hot compound roller, which can effectively avoid the powder loss phenomenon caused by the battery separator and the pole piece after passing through the roller.

Description

Technical Field

[0001] The present application belongs to the field of battery technology, and specifically relates to a battery separator and a preparation method thereof, a battery, and an electrical device. Background Art

[0002] With the promotion and development of new energy vehicles, the lamination process has become a rising star in the internal molding process of lithium batteries with its advantages such as high volume utilization, high efficiency, stable structure, low internal resistance and long cycle life. In the hot composite lamination process, the negative electrode and the diaphragm of the battery are pressed together at a certain temperature to form a unit, and then integrated with the positive electrode. This method can effectively increase the production speed because it combines the die cutting of the electrode and the lamination, simplifies the production steps and significantly improves the efficiency.

[0003] In the newly developed thermal composite lamination process, the diaphragm coating used is a mixture of oxide or boehmite and large particle balls, which has poor heat resistance and high membrane rupture performance. For battery cells with high safety requirements, it is difficult to meet the heat spread and hot box requirements of the battery cells. During use, there is a risk of spherical material falling off, resulting in poor bonding with the negative electrode sheet. In addition, powder falling will occur during the friction with the roller, increasing the risk of foreign matter being introduced into the battery cell. Summary of the invention

[0004] The present invention provides a battery separator and a preparation method, a battery, and an electrical device, aiming to solve the problem that the laminated battery separator in the prior art cannot meet the high safety requirements and has unsatisfactory bonding strength. The battery separator obtained by using the technical solution provided by the present application is not only more heat-resistant, but also can meet the bonding requirements of the separator to the negative electrode and the positive electrode in the hot composite lamination process, and there is no powder falling during the process.

[0005] In one aspect, the present application provides a battery separator, comprising:

[0006] Basement membrane;

[0007] A first adhesive layer, located on one side of the base film, the first adhesive layer has a first thickness H1 μm, and the first adhesive layer has a first coverage C1% on the base film;

[0008] a heat-resistant layer, located on a side of the base film away from the first adhesive layer, the heat-resistant layer having a second thickness H2 μm;

[0009] a second adhesive layer, located on a side of the heat-resistant layer away from the base film, the second adhesive layer having a third thickness H3 μm, and the second adhesive layer having a second coverage C2% for the heat-resistant layer;

[0010] It satisfies: H2>H1+H3, C2=(0.6~1.2)*(H1+H3) / H2%, and C1=(0.1~0.3)*H2 / H1%.

[0011] In some embodiments, the first thickness H1 of the first adhesive layer is 0.5 μm to 1.5 μm.

[0012] In some embodiments, the second thickness H2 of the heat-resistant layer is 1.5 μm to 3 μm.

[0013] In some embodiments, the third thickness H3 of the second adhesive layer is 0.5 μm to 1 μm.

[0014] In some embodiments, the first coverage ratio C1 is 30-50%.

[0015] In some embodiments, the second coverage C2 is 40-60%.

[0016] In some embodiments, the material of the first adhesive layer includes polyvinylidene fluoride.

[0017] In some embodiments, the material of the heat-resistant layer includes bimetallic oxide and fibrous polyimide.

[0018] In some embodiments, the material of the second adhesive layer includes non-fluorine-based polyacrylate.

[0019] In some embodiments, the mass ratio of the bimetallic oxide to the fibrous polyimide is (1.3-3):1.

[0020] In some embodiments, the bimetallic oxide is selected from zinc aluminum oxide and magnesium aluminum oxide.

[0021] In some embodiments, the D of the bimetallic oxide v50 It is 200nm~500nm.

[0022] In some embodiments, the aspect ratio of the fibrous polyimide is 2.5-10.

[0023] In some embodiments, the diameter of the fibrous polyimide is 100 nm to 200 nm, and the length of the fibrous polyimide is 500 nm to 1000 nm.

[0024] In some embodiments, the non-fluorinated polyacrylate includes one or more of styrene-polydimethyl acrylate, styrene-polyethyl acrylate, and hexyl octyl acrylate.

[0025] In some embodiments, the primary particle size of the non-fluorinated polyacrylate is 200 nm to 500 nm.

[0026] On the other hand, the present application also provides a method for preparing a battery separator, comprising the following steps:

[0027] providing a basement membrane;

[0028] preparing a first adhesive layer, wherein the first adhesive layer is located on one side of the base film;

[0029] preparing a heat-resistant layer, wherein the heat-resistant layer is located on a side of the base film away from the first adhesive layer;

[0030] preparing a second adhesive layer, wherein the second adhesive layer is located on a side of the heat-resistant layer away from the base film;

[0031] Wherein, the thickness of the base film, the first adhesive layer, the heat-resistant layer and the second adhesive layer satisfies:

[0032] H2>H1+H3, C2=(0.6~1.2)*(H1+H3) / H2%, and C1=(0.1~0.3)*H2 / H1%.

[0033] The present application also provides a battery, comprising a positive electrode plate, a negative electrode plate and a battery separator, wherein the battery separator is the battery separator in any of the above embodiments; or the battery separator is prepared by the preparation method of the above battery separator.

[0034] The present application also provides an electrical device, comprising the battery in the above embodiment.

[0035] The present application provides a battery separator and a preparation method thereof. The battery separator includes a base film, a first adhesive layer located on one side of the base film, and a heat-resistant layer and a second adhesive layer located on the other side of the base film; the first adhesive layer has a first thickness H1μm, and the first adhesive layer has a first coverage C1% on the base film, the heat-resistant layer has a second thickness H2μm, the second adhesive layer has a third thickness H3μm, and the second adhesive layer has a second coverage C2% on the heat-resistant layer. By setting an asymmetric diaphragm structure, a first adhesive layer is set on the side of the battery diaphragm in contact with the positive electrode, and a double-layer structure of a heat-resistant layer and a second adhesive layer is set on the side of the battery diaphragm in contact with the negative electrode, and at the same time, the three functional layers are set to satisfy the relationship of H2>H1+H3, C2=(0.6~1.2)*(H1+H3) / H2%, and C1=(0.1~0.3)*H2 / H1%, so that the battery diaphragm has excellent heat resistance and improves the overall safety of the battery. In addition, in the process of diaphragm and pole piece composite, the bonding requirements are met after passing through the hot composite roller, which can effectively avoid the powder loss phenomenon caused by the battery diaphragm and the pole piece after passing through the roller. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The technical solution and other beneficial effects of the present application will be made apparent by describing in detail the specific implementation methods of the present application in conjunction with the accompanying drawings.

[0037] Figure 1 A schematic diagram of the structure of a battery separator provided in an embodiment of the present application;

[0038] Figure 2 A schematic diagram of the structure of a battery separator provided as a comparative example of the present application;

[0039] Reference numerals:

[0040] 10 - base film, 20 - first adhesive layer, 30 - heat-resistant layer, 40 - second adhesive layer. DETAILED DESCRIPTION

[0041] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0042] In the description of the present application, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or can communicate with each other; it can be directly connected, or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to the specific circumstances. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined. In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more features.

[0043] The disclosure below provides many different embodiments or examples to realize the different structures of the present application. In order to simplify the disclosure of the present application, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present application.

[0044] The first embodiment of the present application provides a battery separator, such as Figure 1 As shown, including:

[0045] Basement membrane 10;

[0046] A first adhesive layer 20 is located on one side of the base film 10, the first adhesive layer 20 has a first thickness H1 μm, and the first adhesive layer 20 has a first coverage C1% on the base film 10;

[0047] The heat-resistant layer 30 is located on a side of the base film 10 away from the first adhesive layer 20, and the heat-resistant layer 30 has a second thickness H2 μm;

[0048] The second adhesive layer 40 is located on the side of the heat-resistant layer 30 away from the base film 10, the second adhesive layer has a third thickness H3 μm, and the second adhesive layer has a second coverage C2% for the heat-resistant layer 30;

[0049] Satisfies: H2>H1+H3, C2=(0.6~1.2)*(H1+H3) / H2%, C1=(0.1~0.3)*H2 / H1%.

[0050] In some embodiments, the first thickness H1 of the first adhesive layer 20 is 0.5 μm to 1.5 μm. It can be understood that the value of H1 (unit: μm) can be any one of 0.5, 0.7, 0.9, 1.1, 1.3, 1.5 or a range between any two values. The first adhesive layer 20 is used to achieve bonding between the battery separator and the positive electrode of the battery. When the first thickness H1 meets the above value range, it can ensure that the first adhesive layer 20 has an ideal bonding force.

[0051] In some embodiments, the second thickness H2 of the heat-resistant layer 30 is 1.5 μm to 3 μm. It can be understood that the value of H2 (unit: μm) can be any one of 1.5, 2.0, 2.5, 3.0 or a range between any two values. When the second thickness H2 meets the above value range, it can ensure that the heat-resistant layer 30 has a higher film breaking temperature and lower thermal shrinkage.

[0052] In some embodiments, the third thickness H3 of the second adhesive layer 40 is 0.5 μm to 1 μm. It can be understood that the value of H3 (unit: μm) can be any one of 0.5, 0.6, 0.7, 0.8, 0.9, 1 or a range between any two values. The second adhesive layer 40 is used to achieve adhesion between the battery separator and the negative electrode of the battery. When the third thickness H3 meets the above value range, it can ensure that the second adhesive layer 40 has an ideal adhesion.

[0053] In some embodiments, the coverage of the first adhesive layer 20 is 30-50%.

[0054] In some embodiments, the coverage of the second adhesive layer 40 is 40-60%. It is understood that the value of C1 can be any one of 30%, 35%, 40%, 45%, 50% or a range between any two values, and the value of C2 can be any one of 40%, 45%, 50%, 55%, 60% or a range between any two values. When the coverage of the first adhesive layer 20 or the second adhesive layer 40 meets the above range, it has a better bonding effect.

[0055] In some embodiments, the material of the first adhesive layer 20 includes polyvinylidene fluoride (PVDF).

[0056] In some embodiments, the material of the heat-resistant layer 30 includes bimetallic oxide and fibrous polyimide (PI). Bimetallic oxide has a layered structure, which is conducive to the transmission of lithium ions and the adsorption of manganese ions in the battery, preventing the dissolution of manganese ions in the positive electrode of the battery from destroying SEI during operation, resulting in loss of active lithium; at the same time, it has thermal stability and can still maintain structural stability under high temperature conditions. PI has excellent heat resistance, with a heat resistance temperature of up to 400°C. The use of fibrous polyimide modified with hydrophobic groups can improve the water absorption properties of conventional polyimide on the basis of heat resistance, and prevent the heat-resistant layer 30 from absorbing moisture.

[0057] In some embodiments, the material of the second adhesive layer 40 includes non-fluorinated polyacrylate. Non-fluorinated polyacrylate not only has a lower cost than PVDF, but also has an adhesive strength at least twice that of PVDF. While satisfying the composite effect of the battery separator and the battery negative electrode and ensuring that the negative electrode does not fall off during the bonding process, it can also reduce the usage and reduce costs.

[0058] In some embodiments, the primary particle size of polyvinylidene fluoride is 100 nm to 300 nm. It is understandable that the primary particle size of polyvinylidene fluoride (unit: nm) can be any one of 100, 150, 200, 250, 300 or a range between any two values.

[0059] In some embodiments, the mass ratio of the bimetallic oxide to the fibrous polyimide is 1.3 to 3:1. It is understandable that the mass ratio of the bimetallic oxide to the fibrous polyimide can be any one of 1.3, 1.5, 2, 2.5, 3 or a range between any two values.

[0060] In some embodiments, the bimetallic oxide is selected from zinc aluminum oxide or magnesium aluminum oxide.

[0061] In some embodiments, the D of the bimetallic oxide v50 is 200nm~500nm, among which, D v50is the particle size corresponding to the cumulative volume percentage of the bimetallic oxide particles reaching 50%. It can be understood that the D v50 The value of (unit: nm) can be any one of 200, 250, 300, 350, 400, 450, 500 or a range between any two values. As one of the main materials of the heat-resistant layer 30, the particle size of the bimetallic oxide will affect the heat resistance of the coating. When the particle size is large, it affects the stacking density of the coating and thus affects the heat resistance. When the particle size of the bimetallic oxide meets the above value range, it can effectively reduce thermal shrinkage.

[0062] In some embodiments, the aspect ratio of the fibrous polyimide is 2.5-10. It is understandable that the aspect ratio of the fibrous polyimide can be any one of 2.5, 4, 5.5, 7, 8.5, 10 or a range between any two values.

[0063] In some embodiments, the diameter of the fibrous polyimide is 100nm to 200nm, and the length of the fibrous polyimide is 500nm to 1000nm. It can be understood that the value of the diameter of the fibrous polyimide (unit: nm) can be any one of 100, 120, 140, 160, 180, 200 or a range between any two values, and the value of the length of the fibrous polyimide (unit: nm) can be any one of 500, 600, 700, 800, 900, 1000 or a range between any two values. When the aspect ratio of the fibrous polyimide in the heat-resistant layer 30 satisfies the above value range, a network structure can be built. At the same time, the bimetallic oxide plays a filling role in the network structure. The two cooperate with each other, so that the battery separator can not only maintain a complete shape under high temperature conditions, but also greatly increase the film breaking temperature and improve the safety of the battery.

[0064] In some embodiments, the non-fluorinated polyacrylate includes one or more of styrene-polydimethyl acrylate, styrene-polyethyl acrylate, or hexyl octyl acrylate.

[0065] In some embodiments, the primary particle size of the non-fluorinated polyacrylate is 200 nm to 500 nm. It is understandable that the primary particle size of the non-fluorinated polyacrylate (unit: nm) can be any one of 200, 300, 400, 500 or a range between any two values.

[0066] The second embodiment of the present application provides a method for preparing a battery separator, comprising the following steps:

[0067] Providing a base film 10;

[0068] Prepare a first adhesive layer 20, the first adhesive layer 20 is located on one side of the base film 10;

[0069] Prepare a heat-resistant layer 30, which is located on a side of the base film 10 away from the first adhesive layer 20;

[0070] Prepare a second adhesive layer 40, the second adhesive layer 40 is located on the side of the heat-resistant layer 30 away from the base film 10;

[0071] The thickness of the base film 10, the first adhesive layer 20, the heat-resistant layer 30 and the second adhesive layer 40 satisfy:

[0072] H2>H1+H3, C2=(0.6~1.2)*(H1+H3) / H2%, and C1=(0.1~0.3)*H2 / H1%.

[0073] Specifically, the preparation method of the battery separator can be achieved by the following steps:

[0074] S1, selecting a basement membrane 10;

[0075] S2, preparing the first adhesive layer 20: preparing an aqueous solution of PVDF, carboxymethyl cellulose (CMC), an adhesive and a dispersant in a certain proportion, coating the solution on one side of the base film 10, and baking the solution to obtain the first adhesive layer 20;

[0076] S3, preparing the heat-resistant layer 30: preparing a bimetallic oxide, fibrous PI, a dispersant, CMC, an adhesive and a wetting agent into an aqueous solution in a certain proportion, coating the solution on the other side of the base film 10, and baking the solution to obtain the heat-resistant layer 30;

[0077] S4, preparing the second adhesive layer 40: preparing an aqueous solution of non-fluorinated polyacrylate, CMC, adhesive and dispersant in a certain proportion, coating it on the surface of the heat-resistant layer 30, and baking to obtain the second adhesive layer 40, thereby completing the preparation of the battery separator.

[0078] Wherein, the adhesive used in the above preparation method can be polyacrylonitrile-polymethacrylic acid or styrene-butadiene rubber (SBR); the dispersant can be sodium polyacrylate.

[0079] A third embodiment of the present application provides a battery, comprising a positive electrode sheet and a negative electrode sheet, wherein a battery separator according to any of the above embodiments is provided between the positive electrode sheet and the negative electrode sheet.

[0080] A fourth embodiment of the present application provides an electrical device, comprising the battery in the above embodiment.

[0081] The battery provided by the present application is described below in conjunction with specific embodiments:

[0082] Example 1

[0083] This embodiment provides a battery separator, a battery, and methods for preparing the same.

[0084] like Figure 1 As shown, the battery separator includes a base film 10, a first adhesive layer 20, a heat-resistant layer 30 and a second adhesive layer 40. The first adhesive layer 20 is located on one side of the base film 10, the heat-resistant layer 30 is located on the other side of the base film 10, and the second adhesive layer 40 is located on the side of the heat-resistant layer 30 away from the base film 10.

[0085] The battery separator in this embodiment is prepared by the following method:

[0086] S1. A wet-process diaphragm is selected as the base film 10, with a thickness of 9 μm and a porosity of 40%.

[0087] S2. Preparation of the first bonding layer 20: Select Dongyang PVDF with an average particle size of 190 nm, mix the raw materials according to the weight percentage of PVDF: CMC: polyacrylonitrile-polymethacrylic acid: SBR: sodium polyacrylate = 84%: 0.8%: 7.6%: 0.9%: 6.7%, use water as a solvent, and prepare the slurry according to the ratio of 6% solid content of the slurry. Apply the prepared slurry on one side of the base film 10 with a gravure roller, bake at 65°C for 5 minutes to obtain the first bonding layer 20, with a layer thickness of 0.8μm and a coverage of 40%.

[0088] S3, preparation of heat-resistant layer 30: select D v50 The zinc aluminum oxide with a diameter of 300 nm and the modified fibrous PI with a diameter of 150 nm and a length of 700 nm are prepared. The raw materials are mixed according to the weight percentage of zinc aluminum oxide and fibrous PI: dispersant: CMC: adhesive: wetting agent = 54.69%: 36.46%: 0.42%: 1.12%: 7.18%: 0.13%, and water is used as a solvent to prepare the slurry according to the ratio of 35% solid content of the slurry. The prepared slurry is coated on the other side of the base film 10 with a gravure roller, and baked at 75°C for 5 minutes to obtain a heat-resistant layer 30 with a layer thickness of 2 μm.

[0089] S4, preparing the second adhesive layer 40: select styrene-polymethyl acrylate with a primary particle size of 300nm, mix the raw materials according to the weight percentage of styrene-polymethyl acrylate: CMC: adhesive: dispersant = 84%: 0.8%: 8.5%: 6.7%, use water as a solvent, and prepare the slurry according to the ratio of 6% solid content of the slurry. Apply the prepared slurry on the surface of the heat-resistant layer 30 with a gravure roller, bake at 75°C for 5 minutes to obtain the second adhesive layer 40, with a layer thickness of 0.7μm and a coverage of 50%, and complete the preparation of the battery separator.

[0090] The steps for preparing a battery using the above battery separator are as follows:

[0091] 1) Preparation of positive electrode sheet: lithium iron phosphate is used as the main material, and the rest is PVDF, conductive agent, etc. to prepare slurry, the positive electrode accounts for 95.6% of the coating, and the prepared slurry is applied to the carbon-coated aluminum foil to obtain the positive electrode sheet.

[0092] 2) Preparation of negative electrode sheets: artificial graphite, CMC, conductive agent and SBR are used to prepare slurry, which is coated on copper foil and processed to obtain negative electrode sheets, with the negative electrode accounting for 95.5% of the coating.

[0093] 3) Making a diaphragm-negative electrode monolith: The battery diaphragm and the negative electrode sheet are bonded together by hot roller hot pressing using a thermal composite process. The hot roller temperature is 90°C. The unit formed after hot pressing is cut into single sheets with a hot cutter to form a monolithic structure of diaphragm-negative electrode-diaphragm.

[0094] 4) Preparation of electrode group: The separator-negative electrode single sheet and the positive electrode sheet are stacked into an electrode group in the form of a stack, and hot pressing is performed at 90° C. using a hot press to complete the production of the electrode group.

[0095] 5) Packaging and injection: The prepared electrode group is packaged in a soft package and then injected with electrolyte.

[0096] 6) Pre-charging and formation: Pre-charging and forming the battery cell to obtain the battery of the present invention.

[0097] Embodiments 2 to 13

[0098] The battery separators and battery structures provided in Examples 2 to 13 are the same, and only the structural parameters and material parameters are adjusted.

[0099] The relevant structural parameters of the battery separators of Examples 1 to 13 are shown in Table 1, and the material parameters are shown in Table 2.

[0100] Table 1

[0101]

[0102] Table 2

[0103]

[0104] Comparative Example 1

[0105] Select commercial battery separators from Shanghai Enjie Company, such as Figure 2 As shown, the battery separator in this comparative example includes:

[0106] Base film 10, selected as wet-process diaphragm, with a thickness of 9 μm and a porosity of 40%;

[0107] The first adhesive layer 20 has a thickness of 1 μm and is made of PVDF powder;

[0108] The heat-resistant layer 30 has a thickness of 2 μm and is made of a mixed material of boehmite and spherical polyacrylate materials with a primary particle size of 4-7 μm.

[0109] A battery was prepared by a conventional method using the above-mentioned battery separator.

[0110] The batteries prepared in the above-mentioned embodiments and comparative examples were subjected to formation, capacity separation, strength performance and safety performance tests.

[0111] Strength performance test method is as follows:

[0112] (1) Adhesion test:

[0113] The adhesion test was performed with the diaphragm folded in half, and the test conditions were a temperature of 90°C, a surface pressure of 1 MPa, and a time of 60 seconds.

[0114] (2) Heat shrinkage test: refer to GB / T36363-2018, test temperature 130℃ / h and 150℃ / h.

[0115] (3) Membrane rupture temperature test: Use the TMA test method and raise the temperature from room temperature 25°C.

[0116] The safety performance test method is as follows:

[0117] (1) Heat spread test:

[0118] 1C constant current constant voltage charging to 3.65V, cut-off current 0.05C, 100% SOC;

[0119] Fix the two battery cells with a clamp, fix a heating plate on the positive electrode of the first battery cell, heat the battery cell until thermal runaway occurs, stop heating, and record the heat spread time.

[0120] (2) Hot box test:

[0121] 0.5C constant current and constant voltage charge to 4.2V, 0.05C down to 4.2V constant voltage, record the charging process data (V / T / I), and measure and record the battery cell voltage and internal resistance;

[0122] The exterior is fixed with glass clamps;

[0123] The temperature box is raised from the test environment temperature to 130℃±2℃ at a rate of 5℃ / min and maintained at this temperature for 30 minutes, then raised to 135℃±2℃ and maintained at this temperature for 30 minutes, then raised to 140±2℃ and maintained at this temperature for 30 minutes, and so on, until the battery thermal runaway occurs.

[0124] The test results after detection are shown in Table 3.

[0125] Table 3

[0126]

[0127]

[0128] According to the test results in Table 3, it can be seen that the battery diaphragm structure provided by the present application has good adhesion and heat resistance. When the thickness and coverage of the first adhesive layer 20, the heat-resistant layer 30 and the second adhesive layer 40 simultaneously satisfy H2>H1+H3, C2=(0.6~1.2)*(H1+H3) / H2%, and C1=(0.1~0.3)*H2 / H1%, the adhesion of the battery diaphragm, especially the adhesion on the negative electrode side, can be greatly improved. At the same time, the prepared battery also has significant improvements in various heat resistance properties such as thermal shrinkage performance and membrane rupture temperature, which can meet the needs of products with higher safety requirements.

[0129] The above is a detailed introduction to a battery separator and preparation method, battery, and electrical equipment provided in the embodiments of the present application. Specific examples are used in the present application to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the technical solution and core idea of ​​the present application. Ordinary technicians in this field should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some of the technical features therein with equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A battery separator, characterized in that: include: Basement membrane; A first adhesive layer, located on one side of the base film, the first adhesive layer has a first thickness H1 μm, and the first adhesive layer has a first coverage C1% on the base film; a heat-resistant layer, located on a side of the base film away from the first adhesive layer, the heat-resistant layer having a second thickness H2 μm; a second adhesive layer, located on a side of the heat-resistant layer away from the base film, the second adhesive layer having a third thickness H3 μm, and the second adhesive layer having a second coverage C2% on the heat-resistant layer; Satisfy: H2>H1+H3, C2=(0.6~1.2)×(H1+H3) / H2%, and C1=(0.1~0.3)×H2 / H1%; The material of the heat-resistant layer includes bimetallic oxide and fibrous polyimide; Wherein, the D of the bimetallic oxide v50 The thickness of the fibrous polyimide is 200nm-500nm, and the aspect ratio of the fibrous polyimide is 2.5-10.

2. A battery separator according to claim 1, characterized in that: The first thickness H1 of the first adhesive layer is 0.5 μm to 1.5 μm; and / or, The second thickness H2 of the heat-resistant layer is 1.5 μm to 3 μm; and / or, The third thickness H3 of the second adhesive layer is 0.5 μm-1 μm.

3. A battery separator according to claim 1, characterized in that: The first coverage rate C1 is 30-50%; and / or, The second coverage rate C2 is 40-60%.

4. A battery separator according to claim 1, characterized in that: The material of the first bonding layer includes polyvinylidene fluoride; and / or, The material of the second adhesive layer includes non-fluorine-based polyacrylate.

5. A battery separator according to claim 4, characterized in that: The primary particle size of the polyvinylidene fluoride is 100nm~300nm.

6. A battery separator according to claim 4, characterized in that: The mass ratio of the bimetallic oxide to the fibrous polyimide is (1.3-3):1; and / or, The bimetallic oxide is selected from zinc aluminum oxide or magnesium aluminum oxide; and / or, The diameter of the fibrous polyimide is 100 nm to 200 nm, and the length of the fibrous polyimide is 500 nm to 1000 nm.

7. A battery separator according to claim 4, characterized in that: The non-fluorinated polyacrylate includes one or more of styrene-polydimethyl acrylate, styrene-polyethyl acrylate or octyl acrylate; and / or, The primary particle size of the non-fluorinated polyacrylate is 200nm-500nm.

8. A method for preparing a battery separator, characterized in that: The steps include: providing a basement membrane; preparing a first adhesive layer, wherein the first adhesive layer is located on one side of the base film; preparing a heat-resistant layer, wherein the heat-resistant layer is located on a side of the base film away from the first adhesive layer; preparing a second adhesive layer, wherein the second adhesive layer is located on a side of the heat-resistant layer away from the base film; Wherein, the thickness of the base film, the first adhesive layer, the heat-resistant layer and the second adhesive layer satisfies: H2>H1+H3, C2=(0.6~1.2)×(H1+H3) / H2%, and C1=(0.1~0.3)×H2 / H1%; The material of the heat-resistant layer includes bimetallic oxide and fibrous polyimide; Wherein, the D of the bimetallic oxide v50 The thickness of the fibrous polyimide is 200nm-500nm, and the aspect ratio of the fibrous polyimide is 2.5-10.

9. A battery, characterized in that: Including positive electrode sheet, negative electrode sheet and battery separator, The battery separator is the battery separator according to any one of claims 1 to 7; or the battery separator is prepared by the preparation method of the battery separator according to claim 8.

10. An electrical device, characterized in that: Comprising the battery as claimed in claim 9.

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