Diaphragm, battery cell, battery pack and electric equipment

Abstract

The invention relates to the technical field of batteries, in particular to a diaphragm, a battery cell, a battery pack and electric equipment. The diaphragm comprises a base film, an adhesive layer and a ceramic layer, a first area is arranged on any side of the base film in the thickness direction, the first area is located on the edge of the base film, and a second area is defined by the first area; the adhesive layer is arranged on the second area; the ceramic layer is arranged on the first area; in the thickness direction of the base film, the thickness h2 of the ceramic layer is greater than the thickness h1 of the adhesive layer, and a groove is formed in the second side of the diaphragm. The diaphragm disclosed by the invention can effectively prevent the movement of the pole piece, and the ceramic layer can play a certain supporting role on the diaphragm, so that the diaphragm is prevented from quickly shrinking after being heated and generating an internal short circuit, and the safety performance of a battery cell is improved.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and more particularly to a separator, a battery cell, a battery pack, and an electrical device. Background Technology

[0002] The positive electrode active materials in the battery include lithium iron phosphate or ternary materials. During the charging and discharging process, the internal temperature of the battery will rise, and the positive electrode active material will undergo a phase change to release oxygen. The oxygen will crosstalk inside the battery and easily react with the electrolyte, negative electrode active materials, etc., and continuously generate heat, making the battery more prone to thermal runaway risk. Summary of the Invention

[0003] In view of this, the present invention aims to at least partially solve one of the technical problems in the related art. To this end, the present invention provides a separator, a battery cell, a battery pack, and an electrical device, which can effectively prevent the electrode plates from shifting, and the ceramic layer can provide a certain degree of support for the separator, preventing the separator from rapidly shrinking due to heat and causing internal short circuits, thereby improving the safety performance of the battery cell.

[0004] To solve the above-mentioned technical problems, the present invention is implemented as follows: According to one aspect of the present invention, a diaphragm is provided, comprising: A base film has a first region on any side of the base film thickness direction, the first region being located at the edge of the base film, and the first region enclosing a second region; An adhesive layer is disposed on the second region; A ceramic layer is disposed on the first region; In the thickness direction of the base film, the thickness h2 of the ceramic layer is greater than the thickness h1 of the adhesive layer, forming a groove on the second side of the diaphragm.

[0005] In some of these embodiments, the length of the first region is L in the length and / or width direction of the base film, wherein L satisfies: 2mm ≤ L ≤ 3mm.

[0006] In some of these embodiments, the base film comprises a polyolefin; And / or, the adhesive layer comprises an adhesive material, which includes at least one of polyvinylidene fluoride, polyvinyl alcohol, polyimide, carboxymethyl cellulose, polyacrylic acid, polyacrylonitrile, styrene-butadiene rubber, or polymethyl methacrylate.

[0007] In some of these embodiments, the ceramic layer comprises a colloidal substance and ceramic particles; The ceramic particles include at least one of aluminum oxide, boehmite, silicon nitride, or silicon carbide.

[0008] In some of these embodiments, the median particle size D of the ceramic particles v50 The range is 0.2μm to 1.2μm.

[0009] According to another aspect of the present invention, a battery cell is provided, comprising: an electrode assembly; The electrode assembly includes the diaphragm described in any embodiment of the first aspect of the present invention; a positive electrode plate is provided on the second side of the diaphragm, and a negative electrode plate is provided on the first side of the diaphragm; wherein the positive electrode plate is at least partially disposed in the groove.

[0010] In some embodiments, the thickness of the positive electrode is H in the thickness direction of the separator, wherein H, h1, and h2 satisfy: h2 - h1 > H.

[0011] In some embodiments, when the positive electrode is located on the second side of any two of the separators, the ends of the two ceramic layers abut against each other; the two side surfaces of the positive electrode in the thickness direction are respectively attached to the adhesive layer.

[0012] According to a third aspect of the present invention, the present invention also provides a battery pack comprising: a separator as described in any embodiment of the first aspect of the present invention, and / or a battery cell as described in any embodiment of the second aspect of the present invention.

[0013] According to a fourth aspect of the present invention, the present invention also provides an electrical device comprising: a battery cell as described in any embodiment of the second aspect of the present invention; and / or a battery pack as described in the third aspect of the present invention.

[0014] Implementing the technical solution of the present invention has at least the following beneficial effects: 1. In this invention, a ceramic layer and an adhesive layer are provided on one side of the base film, and the thickness of the ceramic layer is greater than the thickness of the adhesive layer, thereby forming a groove on one side of the base film. The electrode can be placed in the groove, which effectively prevents the electrode from shifting. The ceramic layer can also provide some support for the separator, preventing the separator from shrinking rapidly after being heated and causing an internal short circuit, thus improving the safety performance of the battery cell.

[0015] 2. In some preferred embodiments of the present invention, the positive electrode sheet can be placed on the second side of the separator, and the negative electrode sheet can be placed on the first side of the separator. The thickness of the positive electrode sheet and the depth of the groove are matched. Multiple negative electrode sheets, separators and positive electrode sheets are stacked in sequence, and an ordinary separator is placed between the positive electrode sheet and the negative electrode sheet. In this way, the positive electrode sheet can be wrapped between the groove of the separator and the ordinary separator, and the positive electrode sheet is sealed in a "bag". This can effectively seal the oxygen released by the positive electrode material, prevent oxygen from crosstalk and reacting with the electrolyte, negative electrode material, etc., and avoid the generation of excess heat. This can ensure that the battery cell has high energy density and better safety performance.

[0016] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0017] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0018] Figure 1 The figure shown is a schematic diagram of the planar structure of the base film provided by the present invention.

[0019] Figure 2 The diagram shown is a schematic diagram of the diaphragm planar structure provided by the present invention.

[0020] Figure 3 The diagram shown is a cross-sectional view of the diaphragm provided by the present invention.

[0021] Figure 4 The figure shown is a schematic diagram of the cross-sectional structure of the pole group provided by the present invention.

[0022] Figure 5 The figures shown are ARC test diagrams of the battery cells in Embodiment 1 and Comparative Example 1 provided by the present invention.

[0023] Explanation of reference numerals in the attached figures: 10 – Diaphragm; 10A – First side; 10B – Second side; 100 – Base film; 110 – First region; 120 – Second region; 200 – Adhesive layer; 300 – Ceramic layer; 20 – Positive electrode; 30 – Negative electrode.

[0024] The accompanying drawings have illustrated specific embodiments of the invention, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the invention in any way, but rather to illustrate the concept of the invention to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0025] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0026] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges or individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0027] Unless otherwise specified, all embodiments and optional embodiments of the present invention can be combined with each other to form new technical solutions.

[0028] Unless otherwise specified, all technical features and optional technical features of this invention can be combined to form new technical solutions.

[0029] Unless otherwise specified, all steps of the present invention may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0030] Unless otherwise specified, the terms "comprising" and "including" as used in this invention can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0031] Lithium-ion batteries offer advantages such as high energy density, but they are prone to thermal runaway, which can lead to explosions. Currently, to improve the capacity of lithium-ion batteries, ternary materials are often used as the positive electrode active material. However, during battery charging and discharging, the positive electrode made of ternary materials releases oxygen as the internal temperature of the battery rises. This oxygen then reacts with the negative electrode active material, such as graphite or silicon-based materials, or the electrolyte, releasing even more heat. The continuous release of heat can easily lead to thermal runaway. Therefore, how to control the indirect release of oxygen from the positive electrode active material to achieve both high energy density and high safety performance has become an important research topic.

[0032] In view of the technical problems existing in the prior art, the present invention provides a separator, a battery cell, a battery pack, and an electrical device, which can effectively prevent the electrode plates from shifting, and the ceramic layer can provide a certain support for the separator, preventing the separator from shrinking rapidly after being heated and causing an internal short circuit, thereby improving the safety performance of the battery cell.

[0033] The specific technical solution of the present invention is as follows: In some embodiments of the present invention, a diaphragm is provided, comprising: a base film 100, a first region 110 provided on any side of the base film 100 in the thickness direction, the first region 110 being located at the edge of the base film 100, the first region 110 surrounding a second region 120; an adhesive layer 200 provided on the second region 120; and a ceramic layer 300 provided on the first region 110.

[0034] refer to Figure 1 As an example, the base film 100 includes, but is not limited to, any one of polyethylene film, polypropylene film, polyvinyl chloride film, or polyvinylidene fluoride film; those skilled in the art will understand that the planar shape of the base film 100 can be any one of circular, square, elliptical, rectangular, or trapezoidal shapes, or various other shapes, which are not specifically limited in this invention and are all within the protection scope of this invention. On any side of the thickness direction of the base film 100, that is, on a single surface of the base film 100, a first region 110 and a second region 120 are divided. In other words, the first region 110 and the second region 120 constitute a single surface of the base film 100. The first region 110 is located at the edge of the base film 100. For example, if the planar shape of the base film 100 is rectangular, the first region 110 is located at the edge on the single surface of the base film 100, and the first region 110 forms a rectangular frame that fits the plane of the base film 100. Of course, the size of each side of the first region 110 is not specifically limited here. The part enclosed by the first region 110 is the second region 120. That is to say, the second region 120 can be adapted to the plane of the base film 100, and the length and width of the second region 120 are both smaller than the rectangle of the base film 100.

[0035] It is understood that, by way of example, the planar shape of the base film 100 may also be circular. In the thickness direction of the base film 100, a first region 110 and a second region 120 are provided on one side surface of the base film 100. The first region 110 forms an annular shape, and the second region 120 formed by the first region 110 is a circle with a radius or diameter smaller than that of the base film 100.

[0036] refer to Figure 2As an example, to ensure a firm bond between the base film 100 and the positive electrode 20 or the negative electrode 30, an adhesive layer 200 is provided on the second region 120 of the base film 100. It is understood that the adhesive layer 200 may contain, but is not limited to, one or more of polyvinylidene fluoride (PVDF), polyvinyl alcohol (PVA), or polymethyl methacrylate (PMMA). A ceramic layer 300 is provided on the first region 110. It is understood that the ceramic layer 300 contains ceramic particles such as alumina or boehmite. The formed adhesive layer 200 and ceramic layer 300 are both located on one side of the thickness direction of the base film 100 and are on the same side. For example, if the base film 100 is circular, and the first region 110 and the second region 120 on one side of the plane of the base film 100 are respectively an outer ring and a circle formed by the ring, then the ceramic layer 300 is an annulus, and a circular adhesive layer 200 is formed in the middle surrounded by the ceramic layer 300.

[0037] In some embodiments, in the thickness direction of the base film 100, the thickness h2 of the ceramic layer 300 is greater than the thickness h1 of the adhesive layer 200; a groove is formed on the second side 10B of the diaphragm 10.

[0038] refer to Figure 3 In the thickness direction of the base film 100, the ceramic layer 300 on the same side of the base film 100 is thicker than the adhesive layer 200, forming a groove on the second side 10B of the separator 10. Specifically, the adhesive layer 200 forms the bottom wall of the groove, and the ceramic layer 300 forms the side wall. For example, the adhesive layer 200 and ceramic layer 300 on the second side 10B of the separator 10 form a groove. If the planar shape of the separator 10 is rectangular, a rectangular groove is formed; if the planar shape of the separator 10 is circular, a circular groove is formed. When the electrode is placed on the second side 10B of the separator 10, the electrode can be tightly adhered to and bonded to the adhesive layer 200, better preventing electrode movement and ensuring the safety performance of the battery cell. Simultaneously, when the electrode is placed in the groove, the side wall of the electrode abuts against the side wall of the ceramic layer 300, which can support the electrode to a certain extent, effectively preventing the separator 10 from rapidly shrinking after heating and causing an internal short circuit. In a preferred embodiment, the positive electrode 20 is disposed on the second side 10B of the separator 10, and the negative electrode 30 is disposed on the first side 10A of the separator 10. The thickness of the positive electrode 20 is adapted to the depth of the groove. Multiple negative electrode 30s, separators 10 and positive electrode 20 are stacked sequentially, and a common separator is disposed between the positive electrode 20 and the negative electrode 30. In this way, the positive electrode 20 can be wrapped between the groove of the separator 10 and the common separator, and the positive electrode 20 is sealed in a "bag". This can effectively seal the oxygen released by the positive electrode material, prevent oxygen from crosstalk and reacting with the electrolyte, negative electrode material, etc., and avoid the generation of excess heat. This ensures that the battery cell has high energy density and better safety performance.

[0039] The present invention provides a separator by setting a ceramic layer and an adhesive layer on one side of a base film, wherein the thickness of the ceramic layer is greater than the thickness of the adhesive layer, thereby forming a groove on one side of the base film. The electrode can be placed in the groove, which effectively prevents the electrode from shifting. The ceramic layer can also provide a certain support for the separator, preventing the separator from shrinking rapidly after being heated and causing an internal short circuit, thus improving the safety performance of the battery cell.

[0040] In some embodiments, the length of the first region 110 in the length and / or width direction of the base film 100 is L, where L satisfies: 2mm ≤ L ≤ 3mm.

[0041] refer to Figure 1 It is understood that, in the length and / or width direction of the base film 100, the length L of the first region 110 can be any one of 2mm, 2.05mm, 2.1mm, 2.2mm, 2.3mm, 2.4mm, 2.5mm, 2.6mm, 2.7mm, 2.8mm, 2.9mm, or 3.0mm, or any point value between any two. By limiting the size range of the first region 110 in the length and / or width direction of the base film 100, the supporting effect of the ceramic layer on the base film can be effectively improved, preventing internal short circuits caused by rapid shrinkage after heating. If the size of the first region 110 is too small, it cannot provide support for the base film. If the size of the first region 110 is too large, it may affect the size of the electrode, thereby affecting the capacity and cycle performance of the cell.

[0042] In some embodiments, the base film 100 comprises a polyolefin. As an example, the base film 100 comprises a polyolefin, which includes, but is not limited to, one or more of polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyamide, or polyethylene terephthalate.

[0043] In some embodiments, the adhesive layer 200 includes an adhesive substance, which includes, but is not limited to, one or more of polyvinylidene fluoride, polyvinyl alcohol, polyvinylidene fluoride, polyimide, carboxymethyl cellulose, polyacrylic acid, polyacrylonitrile, styrene-butadiene rubber, or polymethyl methacrylate. It is understood that any component that can perform an adhesive function to achieve the technical solution of this invention is within the scope of protection of this invention.

[0044] In some embodiments, the ceramic layer 300 includes a binder and ceramic particles; the ceramic particles include at least one of alumina, boehmite, silicon nitride, or silicon carbide.

[0045] It is understood that the adhesive material includes, but is not limited to, one or more of polyvinylidene fluoride, polyvinyl alcohol, polyvinylidene fluoride, polyimide, carboxymethyl cellulose, polyacrylic acid, polyacrylonitrile, styrene-butadiene rubber, or polymethyl methacrylate; the ceramic particles include, but are not limited to, one or more of alumina, boehmite, silicon nitride, or silicon carbide; the ratio of the adhesive material and the ceramic particles can be adjusted by those skilled in the art according to the present invention, and no specific limitation is made here.

[0046] In some embodiments, the median particle size D of the ceramic particles v50 The range is 0.2μm to 1.2μm.

[0047] It is understandable that the median particle size D of ceramic particles v50 The median particle size can be any one of 0.2μm, 0.3μm, 0.4μm, 0.5μm, 0.6μm, 0.7μm, 0.8μm, 0.9μm, 1.0μm, 1.1μm, or 1.2μm, or any point value between any two. By limiting the median particle size of the ceramic particles, the compaction density of the ceramic layer 300 can be well guaranteed, making the ceramic layer 300 more stable and preventing phenomena such as powder shedding, which would affect the overall performance of the battery cell. If the median particle size of the ceramic particles is too large, the compaction density of the ceramic layer 300 may be too small, which may easily lead to powder shedding.

[0048] In some embodiments of the present invention, a battery cell is also provided, comprising: an electrode assembly; the electrode assembly includes a separator 10 as described in any of the above embodiments; a positive electrode 20 is provided on the second side 10B of the separator 10, and a negative electrode 30 is provided on the first side 10A of the separator 10; wherein the positive electrode 20 is at least partially disposed in a groove.

[0049] refer to Figure 4 The electrode assembly includes multiple positive electrode plates 20, a separator 10, and a negative electrode plate 30. The positive electrode plates 20, the separator 10, and the negative electrode plate 30 can be stacked, wound, or otherwise formed into an electrode assembly. The positive electrode plate 20 is provided on the second side 10B of the separator 10, and the negative electrode plate 30 is provided on the first side 10A of the separator 10. In a preferred embodiment, the positive electrode plate 20 can be completely placed in the groove, and the negative electrode plate 30 is located on the side of the separator 10 away from the positive electrode plate 20. Furthermore, a common separator can be provided between the positive and negative electrodes to prevent short circuits. This ensures that the oxygen generated by the positive electrode during the heating process of the battery cell cannot crosstalk through the edge of the separator, thereby reducing the heat generated by the reaction of oxygen with the electrolyte and the negative electrode and improving the safety of the battery cell.

[0050] In some embodiments, in the thickness direction of the separator 10, the thickness of the positive electrode 20 is H, H, h1 and h2 satisfy: h2-h1>H.

[0051] Understandably, in the preferred embodiment, the thickness of the positive electrode 20 is H in the thickness direction of the separator 10, h2-h1>H, that is, the thickness of the positive electrode 20 is greater than the depth of the groove. Two separators 10 are required on both sides of the thickness direction of one positive electrode 20, and the second side 10B of the separator 10 is close to the positive electrode 20. The ends of the ceramic layers 300 on the two separators 10 abut each other. In this way, when the battery cell is charging and discharging, the battery cell temperature is high, which can melt the adhesive material in the ceramic layer 300 together, thereby placing the positive electrode 20 in a sealed space. This effectively prevents the oxygen generated by the phase change of the positive electrode material from escaping and reacting with the electrolyte, negative electrode material, etc., further increasing the temperature inside the battery cell and increasing the risk of thermal runaway of the battery cell.

[0052] In some embodiments, when the positive electrode 20 is located on the second side 10B of any two separators 10, the ends of the two ceramic layers 300 abut against each other; the two side surfaces of the positive electrode 20 in the thickness direction are respectively attached to the adhesive layer 200.

[0053] It is understandable that when the positive electrode 20 is located on the second side 10B of any two separators 10, the ends of the two ceramic layers 300 abut against each other. This can more stably and firmly hold the positive electrode 20 between the separators 10, effectively preventing the positive electrode 20 from shifting. In addition, the two sides of the positive electrode 20 in the thickness direction are respectively attached to the adhesive layer 200, and the adhesive layer 200 is also bonded to the surface of the positive electrode 200. This can make the positive electrode 20 more stable and improve the safety performance of the cell.

[0054] Optionally, the battery cell may further include a positive electrode plate, a negative electrode plate, and a separator. As an example, the positive electrode plate includes a positive current collector and a positive active material layer disposed on at least one surface of the positive current collector along its thickness direction. The phrase "positive active material layer disposed on at least one surface of the positive current collector" means that the positive active material layer may be disposed on one surface of the positive current collector along its thickness direction, or on two surfaces of the positive current collector along its thickness direction. Here, "surface" can refer to the entire area of ​​the positive current collector or only a portion of it; this application does not impose any particular limitation, as long as the purpose of this application is achieved.

[0055] In some embodiments of the present invention, a battery pack is also provided, including the separator in any of the above embodiments.

[0056] In some embodiments, the battery pack further includes the cells described in any of the above embodiments.

[0057] In some embodiments of the present invention, an electrical device is also provided, comprising: the battery cell in any of the above embodiments.

[0058] In some embodiments, the electrical device further includes the battery pack described in any of the above embodiments.

[0059] As examples, electrical equipment can include vehicles, mobile phones, portable devices, laptops, ships, spacecraft, electric toys, power tools, energy storage devices, amusement equipment, elevators and lifting equipment, etc. Electric toys include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, or electric airplane toys, etc.; power tools include metal cutting power tools, grinding power tools, assembly power tools, and railway power tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc.; energy storage devices can be energy storage walls, base station energy storage, container energy storage, etc.; amusement equipment can be carousels, drop towers, etc. The aforementioned vehicles can be gasoline-powered vehicles, natural gas-powered vehicles, or new energy vehicles. New energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. The vehicle has a battery installed inside, which can be located at the bottom, front, or rear of the vehicle. The battery can be used to power the vehicle; for example, the battery can serve as the vehicle's operating power source. The vehicle may also include a controller and a motor. The controller controls the battery's power supply to the motor, for example, to meet the vehicle's power needs during starting, navigation, and driving. The battery can serve not only as the vehicle's operating power source but also as its driving power source, replacing or partially replacing fuel or natural gas to provide propulsion.

[0060] Since the battery provided in this embodiment of the invention adopts all the technical solutions of the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, and will not be described in detail here.

[0061] The present invention will be described in detail below with reference to the accompanying drawings and examples. However, the implementation and protection of the present invention are not limited thereto. The following embodiments are only some embodiments of the present invention and are not intended to limit the present invention.

[0062] Example 1 Positive electrode: The current collector uses 12-micron thick aluminum foil, and the active material uses a ternary nickel 613 system.

[0063] Negative electrode: The current collector is made of 6-micron thick copper foil, and the active material is graphite.

[0064] Electrolyte: LiPF6 with a lithium salt of 1 mol / L, solvent and composition: EC (ethylene carbonate): EMC (methyl ethyl carbonate): DEC (diethyl carbonate) = 60%: 30%: 10%.

[0065] Separator: PE base membrane is used. The first region of the PE base membrane on the positive electrode sheet side uses ceramic layer (alumina and bronze) particles and adhesive material (polyvinylidene fluoride). The second region has an adhesive layer of polyvinylidene fluoride structure. The two separators encapsulate the positive electrode sheet.

[0066] Cell assembly: slurry homogenization - coating - die cutting - rolling - stacking - casing - welding - electrolyte injection - pre-charging - formation - coating off the production line.

[0067] Comparative Example 1 The only difference between Comparative Example 1 and Example 1 is that the separator used is a PE base membrane, and the first and second regions on the positive electrode side of the base membrane are both composed of ceramic particles and adhesive materials.

[0068] Performance testing: ARC testing steps: (1) Charge the cell under test at a charging rate of 1 / 3C according to constant current and constant voltage (after constant current charging to the upper limit cutoff voltage, switch to constant voltage charging and reduce the cutoff current to 0.05C).

[0069] (2) Before ARC testing, ensure that the battery cell has a normal appearance, no damage, and no dents.

[0070] (3) Before and after the test, the appearance of the battery cells must be photographed to confirm their appearance, and the weight of the battery must be recorded.

[0071] (4) When the battery is placed in the test chamber, first peel off the PET outer film to make the thermocouple more closely contact the battery casing.

[0072] (5) Place the test sample in the ARC calorimeter chamber and adjust the sample position to ensure that the cell does not contact the cavity or upper and lower walls of the ARC calorimeter chamber.

[0073] (6) The test sample is heated from room temperature to 35±2℃ in the chamber and left for 60 minutes. The change in the temperature rise rate of the cell is detected. If the temperature rise exceeds 0.2℃ within 10 minutes (i.e., the temperature rise rate is ≥0.02℃ / min), it is considered that a self-exothermic reaction has occurred inside the cell. The thermal environment is maintained until the cell experiences thermal runaway. If the temperature rise does not exceed 0.2℃ within 10 minutes (i.e., the temperature rise rate is <0.02℃ / min), the next step temperature rise test is continued.

[0074] (7) Repeat step (6) on each temperature step of 5°C.

[0075] (8) The ARC test temperature range is 35℃~200℃; the test results are shown in Table 1.

[0076] Table 1. Test Results: Continued from Table 1 from Figure 5 According to the test results in Table 1, the time interval from self-heating to thermal runaway in the basic group of cells was 774 minutes, with a maximum temperature of 461℃. In contrast, the time interval from self-heating to thermal runaway in the new separator group of cells was 1686 minutes, with a maximum temperature of 400℃. Compared to the basic group, the thermal runaway incubation time was extended by 912 minutes and the maximum temperature was reduced by 60℃. This indicates that the new separator delayed the internal reaction and heat generation before thermal runaway occurred. After thermal runaway, the sealing effect prevented oxygen from fully reacting with the electrolyte and negative electrode, thus reducing the maximum temperature.

[0077] The parts of this invention not described in detail are techniques known to those skilled in the art.

[0078] The basic principles of the present invention have been described above with reference to specific embodiments. However, it should be noted that the advantages, benefits, and effects mentioned in the present invention are merely examples and not limitations, and should not be considered as essential features of each embodiment of the present invention. Furthermore, the specific details disclosed above are for illustrative and facilitative purposes only, and are not limitations. These details do not limit the present invention to the necessity of employing the aforementioned specific details.

[0079] It should be noted that the terms "and / or" or " / " used herein are merely descriptions of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. The singular forms "a," "described," and "the" used in the embodiments of the invention and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0080] In the detailed description and claims, a list of items connected by the terms "at least one of," "at least one of," "at least one of," or other similar terms may mean any combination of the listed items. For example, if items A and B are listed, then the phrase "at least one of A and B" means only A; only B; or A and B. In another example, if items A, B, and C are listed, then the phrase "at least one of A, B, and C" means only A; or only B; only C; A and B (excluding C); A and C (excluding B); B and C (excluding A); or all of A, B, and C. Item A may contain a single element or multiple elements. Item B may contain a single element or multiple elements. Item C may contain a single element or multiple elements.

[0081] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A diaphragm, characterized in that, include: A base film has a first region on any side of the base film thickness direction, the first region being located at the edge of the base film, and the first region enclosing a second region; An adhesive layer is disposed on the second region; A ceramic layer is disposed on the first region; In the thickness direction of the base film, the thickness h2 of the ceramic layer is greater than the thickness h1 of the adhesive layer, forming a groove on the second side of the diaphragm.

2. The diaphragm according to claim 1, characterized in that, In the length and / or width direction of the base film, the dimension of the first region is L, and L satisfies: 2mm≤L≤3mm.

3. The diaphragm according to claim 1, characterized in that, The base membrane comprises polyolefin; And / or, the adhesive layer comprises an adhesive material, which includes at least one of polyvinylidene fluoride, polyvinyl alcohol, polyimide, carboxymethyl cellulose, polyacrylic acid, polyacrylonitrile, styrene-butadiene rubber, or polymethyl methacrylate.

4. The diaphragm according to claim 1, characterized in that, The ceramic layer comprises a colloidal substance and ceramic particles; The ceramic particles include at least one of aluminum oxide, boehmite, silicon nitride, or silicon carbide.

5. The diaphragm according to claim 4, characterized in that, The median particle size D of the ceramic particles v50 The range is 0.2μm to 1.2μm.

6. A battery cell, characterized in that, include: pole group; The electrode assembly includes the diaphragm according to any one of claims 1 to 5; a positive electrode plate is provided on the second side of the diaphragm, and a negative electrode plate is provided on the first side of the diaphragm; wherein the positive electrode plate is at least partially disposed in the groove.

7. The battery cell according to claim 6, characterized in that, In the thickness direction of the separator, the thickness of the positive electrode is H, and H, h1, and h2 satisfy: h2-h1>H.

8. The battery cell according to claim 6, characterized in that, When the positive electrode is located on the second side of any two of the separators, the ends of the two ceramic layers abut against each other; the two side surfaces of the positive electrode in the thickness direction are respectively attached to the adhesive layer.

9. A battery pack, characterized in that, include: The diaphragm according to any one of claims 1 to 5; And / or, the battery cell according to any one of claims 6 to 8.

10. An electrical appliance, characterized in that, include: The battery cell according to any one of claims 6 to 8; And / or, the battery pack of claim 9.

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