Diaphragm and battery cell

Abstract

The utility model discloses a diaphragm and a battery cell. The diaphragm comprises a base material, the base material is coated with the first insulating layer, the first insulating layer comprises a first part, a second part and a third part, and the two ends of the second part are connected to the first part and the third part respectively; and the second insulating layer is coated on the first part. According to the diaphragm disclosed by the utility model, the yield of the battery can be effectively improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to battery technology field especially is involved a diaphragm and electric core. BACKGROUND

[0002] In the related art, the main purpose of the battery needle test is to simulate the internal short circuit condition of the battery when a sharp object pierces into the battery, and to evaluate the safety of the battery under such extreme conditions. Through the test, the reaction of the battery when the internal short circuit occurs can be understood, including whether there will be smoke, fire, rupture and other dangerous conditions.

[0003] Specifically, the specific process of the needle test is to pierce a steel needle through the center position of the maximum surface of the battery and keep for 5 seconds, so as to observe and record the reaction of the battery during the piercing process, such as whether it will catch fire, explode, etc. However, the result of the existing battery through the needle test is not ideal, which will result in a low yield of the battery. SUMMARY

[0004] The utility model aims at at least solving one of the technical problems existing in the prior art. To this end, the utility model provides a diaphragm, which can effectively improve the yield of the battery.

[0005] The utility model further provides an electric core.

[0006] According to the diaphragm of the first aspect embodiment of the utility model, comprising:

[0007] A base material;

[0008] A first insulating layer coated on the base material, the first insulating layer comprising a first part, a second part and a third part, both ends of the second part being connected to the first part and the third part respectively;

[0009] A second insulating layer coated on the first part.

[0010] According to the diaphragm of the utility model embodiment, at least has following beneficial effect: the first insulating layer is coated on the base material, the first insulating layer includes the first part, the second part and the third part, wherein, the second insulating layer is coated on the first part;That is, on the basis that the first insulating layer is coated on the base material, the second insulating layer is also coated on the part position of the first insulating layer, which can effectively improve the thickness of the diaphragm, so that when the diaphragm is applied in the battery and the needle test is carried out, the needle can not easily pierce the diaphragm, which can improve the passing rate of the battery needle test. Specifically, the diaphragm can effectively improve the yield of the battery.

[0011] According to some embodiments of the utility model, the diaphragm further comprises a moisturizing layer coated on the third part.

[0012] According to the diaphragm of some embodiments of the utility model, along the length direction of the base material, the size of the first insulation layer is L1, the size of the third part is L2, 1 / 7≤L2 / L1≤1 / 6.

[0013] According to the diaphragm of some embodiments of the utility model, the sum of the thicknesses of the moisturizing layer, the third part and the base material is A, 20um≤A≤30um.

[0014] According to the diaphragm of some embodiments of the utility model, along the length direction of the base material, the size of the first insulation layer is L1, the size of the first part is L3, 1 / 7≤L3 / L1≤1 / 6.

[0015] According to the diaphragm of some embodiments of the utility model, the first insulation layer and the second insulation layer are both provided with two, one first insulation layer and one second insulation layer are located on one side of the base material, and the other first insulation layer and the other second insulation layer are located on the other side of the base material.

[0016] According to the diaphragm of some embodiments of the utility model, the thickness of the first insulation layer is B, 1.5um≤B≤2.5um.

[0017] According to the diaphragm of some embodiments of the utility model, the sum of the thicknesses of the second insulation layer, the first part and the base material is C, 40um≤C≤50um.

[0018] According to the second aspect of the utility model embodiment, the electric core includes the diaphragm of any one in the first aspect of the utility model embodiment.

[0019] According to the electric core of the utility model embodiment, at least has following beneficial effect: first insulation layer is coated on base material, first insulation layer includes first part, second part and third part, wherein, second insulation layer is coated on first part, that is, on the basis that first insulation layer is coated on base material, second insulation layer is also coated on the position of a part of first insulation layer, this can effectively improve the thickness of diaphragm, so that when diaphragm is applied in battery, needle can not easily pierce diaphragm, this can improve the passing rate of battery needle test, specifically, diaphragm can effectively improve the yield of battery, further, after the electric core includes the diaphragm described above, the passing rate of electric core through needle test is higher, and the yield of electric core is higher.

[0020] According to the electric core of some embodiments of the utility model, the electric core further includes:

[0021] Positive plate;

[0022] Negative plate;

[0023] The diaphragm is located between the positive electrode sheet and the negative electrode sheet, and the positive electrode sheet, the diaphragm and the negative electrode sheet are laminated and wound to form the battery cell, the first part is the winding end point of the battery cell, and the third part is the winding starting point of the battery cell.

[0024] Additional aspects and advantages of the present application will be given in part in the following description, and become apparent from the following description, or be learned by practice of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0025] The present application will be further described below in conjunction with the drawings and embodiments, wherein:

[0026] Figure 1 is a sectional view of the diaphragm of some embodiments of the present application;

[0027] Figure 2 is a top view of the diaphragm of some embodiments of the present application;

[0028] Figure 3 is a top view of the battery cell of some embodiments of the present application.

[0029] REFERENCE NUMERALS

[0030] Diaphragm 100, base material 200, first insulating layer 300, first part 310, second part 320, third part 330, second insulating layer 400, moisturizing layer 500, battery cell 600, positive electrode sheet 700, negative electrode sheet 800. DETAILED DESCRIPTION

[0031] The embodiments of the present application will be described in detail below, and examples of the embodiments are shown in the drawings, wherein the same or similar reference numerals represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by reference to the drawings are exemplary and are only used to explain the present application, and cannot be understood as a limitation of the present application.

[0032] In the description of the present application, it should be understood that the orientation description, such as the orientation or position relationship indicated by up, down, front, back, left, right, etc. is based on the orientation or position relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the present application.

[0033] In the description of the utility model, if several meanings are more than one, the meaning of multiple is more than two, greater than, less than, more than, etc. Understand as not including the number, above, below, within, etc. Understand as including the number. If it is described to the first, the second is only used for distinguishing the purpose of technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features or implicitly indicating the relationship between the indicated technical features.

[0034] In the description of the utility model, unless otherwise explicitly limited, the words such as setting, installation, connection should be understood broadly, and the person skilled in the art can determine the specific meaning of the above words in the utility model in combination with the specific content of the technical scheme.

[0035] In the description of the utility model, the description of reference terms "one embodiment", "some embodiments", "illustrative embodiment", "example", "specific example" or "some examples" means that the specific features, structures, materials or characteristics described in combination with the embodiment or example are included in at least one embodiment or example of the utility model. In the specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0036] The battery can be a lithium ion battery, a sodium ion battery, a sodium lithium ion battery, a lithium metal battery, a sodium metal battery, a lithium sulfur battery, a magnesium ion battery, a nickel hydrogen battery, a nickel cadmium battery, a lead storage battery, etc. The present application embodiment is not limited thereto.

[0037] The battery generally includes a cell. The cell includes a positive electrode, a negative electrode and a separator. In the process of charging and discharging the battery, active ions (such as lithium ions) are inserted and extracted between the positive electrode and the negative electrode. The separator is arranged between the positive electrode and the negative electrode, which can prevent the positive and negative electrodes from short-circuiting, and at the same time can allow the active ions to pass through.

[0038] In some embodiments, the positive electrode can be a positive electrode sheet, which can include a positive electrode current collector and a positive electrode active material arranged on at least one surface of the positive electrode current collector.

[0039] As an example, the positive electrode current collector has two opposite surfaces in its own thickness direction, and the positive electrode active material is arranged on any one or both of the two opposite surfaces of the positive electrode current collector.

[0040] As an example, the positive electrode current collector can employ a metal foil or a composite current collector. For example, as a metal foil, aluminum subjected to silver plating on the surface, stainless steel subjected to silver plating on the surface, stainless steel, copper, aluminum, nickel, a carbon electrode, carbon, nickel, or titanium, or the like can be employed. The composite current collector can include a high molecular material base layer and a metal layer. The composite current collector can be formed by forming a metal material (aluminum, an aluminum alloy, nickel, a nickel alloy, titanium, a titanium alloy, silver, and a silver alloy, or the like) on a high molecular material base material (such as a base material of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, or the like).

[0041] As an example, the positive electrode active material can include at least one of a lithium-containing phosphate, a lithium transition metal oxide, and a modified compound of each thereof. However, the present application is not limited to these materials, and other conventional materials that can be used as a battery positive electrode active material can also be used. These positive electrode active materials can be used alone only one or two or more can be used in combination. Among them, examples of the lithium-containing phosphate can include, but are not limited to, at least one of lithium iron phosphate (such as LiFeP04 (which can also be referred to simply as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnP04), a composite material of lithium manganese phosphate and carbon, lithium manganese iron phosphate, and a composite material of lithium manganese iron phosphate and carbon. Examples of the lithium transition metal oxide can include, but are not limited to, at least one of lithium cobalt oxide (such as LiCo02), lithium nickel oxide (such as LiNi02), lithium manganese oxide (such as LiMn02, LiMn204), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (which can also be referred to simply as NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O2 (which can also be referred to simply as NCM523), LiNi 0.5 Co 0.25 Mn 0.25 O2 (which can also be referred to simply as NCM211), LiNi 0.6 Co 0.2 Mn 0.2 O2 (which can also be referred to simply as NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O2 (which can also be referred to simply as NCM811), lithium nickel cobalt aluminum oxide (such as LiNi 0.85 Co 0.15 Al 0.05 O2), and a modified compound thereof.

[0042] In some embodiments, the positive electrode can employ a foamed metal. The foamed metal can be foamed nickel, foamed copper, foamed aluminum, foamed alloy, etc. When the foamed metal is used as the positive electrode, the foamed metal surface can be free of positive electrode active material, or can be provided with positive electrode active material. As an example, the foamed metal can be filled or / and deposited with a lithium source material, potassium metal or sodium metal. The lithium source material can be lithium metal and / or lithium-rich material.

[0043] In some embodiments, the negative electrode can be a negative electrode sheet, which can include a negative electrode current collector.

[0044] As an example, the negative electrode current collector can employ a metal foil, foamed metal or composite current collector. For example, as the metal foil, silver surface treated aluminum or stainless steel, stainless steel, copper, aluminum, nickel, carbon electrode, nickel or titanium, etc. can be employed. The foamed metal can be foamed nickel, foamed copper, foamed aluminum, foamed alloy, etc. The composite current collector can include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material base material (such as a base material of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0045] As an example, the negative electrode sheet can include a negative electrode current collector and a negative electrode active material provided on at least one surface of the negative electrode current collector.

[0046] As an example, the negative electrode current collector has two surfaces opposite in the thickness direction thereof, and the negative electrode active material is provided on either one or both of the two opposite surfaces of the negative electrode current collector.

[0047] As an example, the negative electrode active material can employ a negative electrode active material known in the art for use in a battery. As an example, the negative electrode active material can include at least one of artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based material, tin-based material, lithium titanate, etc. The silicon-based material can be selected from at least one of elemental silicon, silicon oxide compound, silicon-carbon composite, silicon-nitrogen composite and silicon alloy. The tin-based material can be selected from at least one of elemental tin, tin oxide compound and tin alloy. However, the present application is not limited to these materials, and other conventional materials that can be used as a battery negative electrode active material can also be used. These negative electrode active materials can be used alone or in combination of two or more.

[0048] In some embodiments, the material of the positive electrode current collector can be aluminum, and the material of the negative electrode current collector can be copper.

[0049] In some embodiments, the battery cell further includes a separator disposed between the positive electrode and the negative electrode.

[0050] In some embodiments, the separator is a separator film. The separator film can be any porous structure separator film known to have good chemical stability and mechanical stability.

[0051] For example, the separator film can be made of at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator film can be a single layer film or a multi-layer composite film. When the separator film is a multi-layer composite film, the materials of the layers can be the same or different. The separator can be a separate component between the positive and negative electrodes or can be attached to the surface of the positive and negative electrodes.

[0052] In some embodiments, the separator is a solid-state electrolyte. The solid-state electrolyte is disposed between the positive and negative electrodes and functions to transport ions and separate the positive and negative electrodes.

[0053] In some embodiments, the battery further includes an electrolyte that functions to conduct ions between the positive and negative electrodes. The electrolyte can be in a liquid state, a gel state, or a solid state. The liquid electrolyte includes an electrolyte salt and a solvent.

[0054] In some embodiments, the electrolyte salt can include at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bisfluorosulfonylimide, lithium bis-trifluoromethanesulfonylimide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluoro oxalate borate, lithium di-oxalate borate, lithium difluoro di-oxalate phosphate, and lithium tetrafluoro oxalate phosphate.

[0055] In some embodiments, the solvent can include at least one of ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, butyrosulfone, methyl ethyl sulfone, and diethyl sulfone. The solvent can also be an ether solvent. The ether solvent can include one or more of ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyl tetrahydrofuran, diphenyl ether, and crown ether.

[0056] The gel electrolyte includes a polymer as a skeleton network of the electrolyte, in combination with an ionic liquid-lithium salt.

[0057] The solid-state electrolyte includes a polymer solid-state electrolyte, an inorganic solid-state electrolyte, and a composite solid-state electrolyte.

[0058] As an example, the polymer solid-state electrolyte can be a polyether (polyethylene oxide), a polysiloxane, a polycarbonate, a polyacrylonitrile, a polyvinylidene fluoride, a polymethyl methacrylate, a single-ion polymer, a polyionic liquid-lithium salt, a cellulose, or the like.

[0059] As an example, the inorganic solid-state electrolyte can include one or more of an oxide solid-state electrolyte (crystalline perovskite, sodium superionic conductor, garnet, amorphous LiPON thin film), a sulfide solid-state electrolyte (crystalline lithium superionic conductor (lithium germanium phosphorous sulfide, argyrodite), amorphous sulfide), and a halide solid-state electrolyte, a nitride solid-state electrolyte, and a hydride solid-state electrolyte.

[0060] As an example, the composite solid-state electrolyte is formed by adding an inorganic solid-state electrolyte filler to a polymer solid-state electrolyte.

[0061] In some embodiments, the electric core is in a jelly-roll structure. The positive electrode sheet and the negative electrode sheet are wound into the jelly-roll structure.

[0062] In some embodiments, the electric core is in a stack structure.

[0063] As an example, a plurality of positive electrode sheets and a plurality of negative electrode sheets can be provided, respectively, and the plurality of positive electrode sheets and the plurality of negative electrode sheets are alternately and stacked.

[0064] As an example, a plurality of positive electrode sheets can be provided, and the negative electrode sheet is folded to form a plurality of folded segments which are stacked. One positive electrode sheet is clamped between adjacent folded segments.

[0065] As an example, both the positive electrode sheet and the negative electrode sheet are folded to form a plurality of folded segments which are stacked.

[0066] As an example, a plurality of separators can be provided, and each of the plurality of separators is provided between any adjacent positive electrode sheet or negative electrode sheet.

[0067] As an example, the separators can be continuously provided, and each of the separators is provided between any adjacent positive electrode sheet or negative electrode sheet by folding or winding.

[0068] In some embodiments, the electric core can have a cylindrical shape, a flat shape, or a multi-prism shape, or the like.

[0069] In some embodiments, the electric core can be provided with a tab. The tab can guide current out of the electric core. The tab can include a positive tab and a negative tab.

[0070] In some embodiments, the battery can include a housing. The housing can be used to encapsulate the electric core and other components such as the electrolyte. The housing can be a steel shell, an aluminum shell, a plastic shell (such as polypropylene), a composite metal shell (such as a copper-aluminum composite shell), or an aluminum-plastic film, or the like.

[0071] As an example, the battery can be a cylindrical battery, a prismatic battery, a pouch battery, or other shaped battery, and the prismatic battery includes, but is not limited to, a square battery, a blade battery, a multi-prismatic battery, for example, a hexagonal prismatic battery, etc.

[0072] The battery mentioned in the embodiments of the present application refers to a single physical module including one or more batteries to provide higher voltage and capacity.

[0073] In some embodiments, the battery can be a battery module, and when there are multiple batteries, the multiple batteries are arranged and fixed to form a battery module.

[0074] In some embodiments, the battery can be a battery pack, and the battery pack includes a box and a battery, and the battery or the battery module is contained in the box.

[0075] In some embodiments, the box can be part of the chassis structure of the vehicle. For example, part of the box can be at least part of the floor of the vehicle, or part of the box can be at least part of the cross beam and the longitudinal beam of the vehicle.

[0076] The embodiments of the present application provide a power consumption device using a battery as a power source, and the power consumption device can be, but is not limited to, a mobile phone, a tablet, a notebook computer, an electric toy, an electric tool, an electric vehicle, an electric car, a ship, a spacecraft, etc. Among them, the electric toy can include a fixed or mobile electric toy, for example, a game console, an electric car toy, an electric ship toy, and an electric plane toy, etc., and the spacecraft can include an airplane, a rocket, a space shuttle, a spacecraft, etc.

[0077] In the related art, the main purpose of the battery needle test is to simulate the internal short circuit condition of the battery when it is pierced by a sharp object, and to evaluate the safety of the battery under such extreme conditions. Through this test, the reaction of the battery when it is internally short-circuited can be understood, including whether there will be smoke, fire, rupture, etc.

[0078] Specifically, the specific process of the needle test is to pierce the center of the largest surface of the battery with a steel needle and keep it for 5 seconds, so as to observe and record the reaction of the battery during the piercing process, such as whether it catches fire, explodes, etc. However, the results of the existing battery through the needle test are not ideal, which will lead to a low yield of the battery. Therefore, the present application proposes a separator.

[0079] Please refer to Figures 1 to 2In some embodiments, the separator 100 comprises a substrate 200, a first insulating layer 300 and a second insulating layer 400. The substrate 200 refers to a separator substrate commonly used in the art, i.e., the separator 100 of the present application is further formed by coating the first insulating layer 300 and the like on the separator substrate. The substrate 200 can be in the shape of a long strip. The first insulating layer 300 is coated on the substrate 200. The first insulating layer 300 can be a ceramic material, which can further insulate the positive electrode sheet 700 and the negative electrode sheet 800, thereby improving the safety of the battery. The first insulating layer 300 comprises a first portion 310, a second portion 320 and a third portion 330, and the two ends of the second portion 320 are connected to the first portion 310 and the third portion 330, respectively. That is, along the length direction of the first insulating layer 300, the first portion 310, the second portion 320 and the third portion 330 are arranged in sequence. The second insulating layer 400 is coated on the first portion 310. The material of the second insulating layer 400 can be a glass fiber material. The material of the first insulating layer 300 is different from that of the second insulating layer 400. Specifically, the first insulating layer 300 is coated on the substrate 200, and the first insulating layer 300 comprises the first portion 310, the second portion 320 and the third portion 330, wherein the second insulating layer 400 is coated on the first portion 310; that is, on the basis of coating the first insulating layer 300 on the substrate 200, the second insulating layer 400 is further coated on a part of the first insulating layer 300, which can effectively increase the thickness of the separator 100, so that when the separator 100 is applied in a battery and subjected to a needle test, the needle cannot easily pierce the separator 100, which can improve the pass rate of the battery needle test. Specifically, the separator 100 can effectively improve the yield of the battery.

[0080] It should be noted that in the prior art, the result of the battery needle test is not ideal, which may be because the existing separator 100 is easily pierced. In the present application, after the first insulating layer 300 and the second insulating layer 400 are provided on the substrate 200, the final thickness of the separator 100 can be effectively increased. In addition, if the second insulating layer 400 is coated on the first portion 310, the second portion 320 and the third portion 330, it may cause the volume of the battery cell 600 to increase after winding, thereby reducing the volume energy density of the battery cell 600. Therefore, the second insulating layer 400 is provided on the first portion 310.

[0081] Further, please refer to Figures 1 to 2In some embodiments, the separator 100 further comprises a moisturizing layer 500 coated on the third part 330. The material of the moisturizing layer 500 can be silicon material or aramid. The moisturizing layer 500 can retain a certain amount of electrolyte. That is, after the moisturizing layer 500 is arranged on the third part 330, when the separator 100 is applied in the battery cell 600, the moisturizing layer 500 can store more electrolyte, thereby improving the wetting effect of the pole piece, which can effectively improve the lithium precipitation condition and improve the long cycle performance of the battery cell 600. In some embodiments, after the separator 100 and the pole piece are wound, the moisturizing layer 500 can be located at the innermost layer or the outermost layer of the battery cell 600.

[0082] Further, please refer to Figures 1 to 2 In some embodiments, along the length direction of the base material 200, the size of the first insulating layer 300 is L1, the size of the third part 330 is L2, and 1 / 7≤L2 / L1≤1 / 6. Specifically, the proportion of the third part 330 in the total length of the first insulating layer 300 can be 1 / 7, 3 / 20 or 1 / 6. When the proportion of the third part 330 in the total length of the first insulating layer 300 is less than 1 / 7, the length of the third part 330 is small, that is, the length of the moisturizing layer 500 is also small, which is not good for the liquid storage capacity of the moisturizing layer 500 after the separator 100 is wound. When the proportion of the third part 330 in the total length of the first insulating layer 300 is greater than 1 / 6, the length of the third part 330 is large, and the length of the moisturizing layer 500 is also large, which can increase the volume of the battery cell 600 after the separator 100 is wound, thereby reducing the energy density of the battery.

[0083] Further, please refer to Figures 1 to 2 In some embodiments, the sum of the thicknesses of the moisturizing layer 500, the third part 330 and the base material 200 is A, and 20 μm≤A≤30 μm. Specifically, the sum of the thicknesses of the moisturizing layer 500, the third part 330 and the base material 200 can be 20 μm, 22 μm, 25 μm, 28 μm or 30 μm. When the sum of the thicknesses of the moisturizing layer 500, the third part 330 and the base material 200 is greater than 30 μm, it can cause the separator 100 to occupy too much volume of the battery cell 600, thereby reducing the energy density of the battery cell 600. When the sum of the thicknesses of the moisturizing layer 500, the third part 330 and the base material 200 is less than 20 μm, due to the small thickness, it can cause the liquid storage capacity of the moisturizing layer 500 to be not good or the thickness of the first insulating layer 300 to be small, thereby reducing the performance of the separator 100.

[0084] Further, please refer to Figures 1 to 2In some embodiments, the size of the first insulating layer 300 along the length direction of the substrate 200 is L1, the size of the first portion 310 is L3, and 1 / 7≤L3 / L1≤1 / 6. Specifically, the first portion 310 can account for 1 / 7, 3 / 20, or 1 / 6 of the total length of the first insulating layer 300. When the first portion 310 accounts for less than 1 / 7 of the total length of the first insulating layer 300, the length of the first portion 310 is small, and the length of the second insulating layer 400 is also small. After the separator 100 is wound, the second insulating layer 400 can not be able to wrap around the center of the battery cell 600, which can cause the needle to easily penetrate the separator 100 in the needle test, reducing the yield of the battery. When the third portion 330 accounts for more than 1 / 6 of the total length of the first insulating layer 300, the length of the third portion 330 is large, and the length of the second insulating layer 400 is also large. This can cause the volume of the battery cell 600 to increase after the separator 100 is wound, reducing the energy density of the battery.

[0085] Further, please refer to Figures 1 to 2 In some embodiments, the first insulating layer 300 and the second insulating layer 400 are both provided, one first insulating layer 300 and one second insulating layer 400 are located on one side of the substrate 200, and the other first insulating layer 300 and the other second insulating layer 400 are located on the other side of the substrate 200. Specifically, the substrate 200 has a first insulating layer 300 and a second insulating layer 400 on both sides, which can effectively ensure that the separator 100 can pass the needle test, thereby improving the yield of the battery cell 600.

[0086] Further, please refer to Figures 1 to 2 In some embodiments, the thickness of the first insulating layer 300 is B, and 1.5 μm≤B≤2.5 μm. Specifically, the thickness of the first insulating layer 300 can be 1.5 μm, 1.8 μm, 2 μm, or 2.5 μm. When the thickness of the first insulating layer 300 is less than 1.5 μm, the thickness of the first insulating layer 300 is small, which can cause the separator 100 to be easily penetrated, and when the separator 100 is applied to the battery, the needle test pass rate of the battery is reduced. When the thickness of the first insulating layer 300 is greater than 2.5 μm, the thickness of the first insulating layer 300 can be large, and when the separator 100 is applied to the battery, the energy density of the battery can be low.

[0087] Further, please refer to Figures 1 to 2In some embodiments, the sum of the thicknesses of the second insulating layer 400, the first portion 310, and the substrate 200 is C, 40 pm≤C≤50 pm. Specifically, the sum of the thicknesses of the second insulating layer 400, the first portion 310, and the substrate 200 can be 40 pm, 42 pm, 45 pm, 48 pm, or 50 pm. When the sum of the thicknesses of the second insulating layer 400, the first portion 310, and the substrate 200 is greater than 50 pm, this can result in the separator 100 occupying too much volume of the battery cell 600, thereby reducing the energy density of the battery cell 600. When the sum of the thicknesses of the second insulating layer 400, the first portion 310, and the substrate 200 is less than 40 pm, due to the small thickness, this can result in poor puncture resistance of the second insulating layer 400 or a small thickness of the first insulating layer 300, thereby resulting in poor performance of the separator 100.

[0088] Reference is made to Figure 3 In some embodiments, the battery cell 600 includes the separator 100 of any of the above embodiments. Specifically, the first insulating layer 300 is coated on the substrate 200, and the first insulating layer 300 includes the first portion 310, the second portion 320, and the third portion 330, wherein the second insulating layer 400 is coated on the first portion 310; that is, on the basis of the substrate 200 being coated with the first insulating layer 300, the second insulating layer 400 is further coated on a portion of the first insulating layer 300, which can effectively increase the thickness of the separator 100, so that when the separator 100 is applied in a battery and subjected to a needle puncture test, the needle cannot easily puncture the separator 100, which can improve the pass rate of the battery needle puncture test. Specifically, the separator 100 can effectively improve the yield of the battery. Further, after the battery cell 600 includes the above separator 100, the battery cell 600 has a high pass rate in the needle puncture test, and the battery cell 600 has a high yield.

[0089] Further reference is made to Figure 3In some embodiments, the battery cell 600 further comprises a positive electrode sheet 700 and a negative electrode sheet 800. The separator 100 is located between the positive electrode sheet 700 and the negative electrode sheet 800, and the positive electrode sheet 700, the separator 100 and the negative electrode sheet 800 are laminated and wound to form the battery cell 600. The first part 310 is the winding end of the battery cell 600, and the third part 330 is the winding start of the battery cell 600. That is, the positive electrode sheet 700, the separator 100 and the negative electrode sheet 800 are laminated and wound to form a cylindrical battery cell 600, wherein the third part 330 is located in the innermost layer of the battery cell 600, and the third part 330 has the moisture retention layer 500, which can effectively improve the wettability of the inside of the battery cell 600, so that the performance of the battery cell 600 is better. Further, the first part 310 is located in the outermost layer of the battery cell 600, and when the battery cell 600 is subjected to the needle test, the needle will first be punctured on the second insulating layer 400 and the first insulating layer 300, which can effectively improve the needle penetration rate of the battery cell 600, and the yield of the battery cell 600 is higher.

[0090] The embodiments of the utility model are described in detail above in combination with the drawings, but the utility model is not limited to the above-mentioned embodiments, and various changes can be made within the knowledge range possessed by the ordinary skilled in the art without departing from the purpose of the utility model. In addition, the embodiments of the utility model and the features in the embodiments can be combined with each other without conflict.

Claims

1. A diaphragm, characterized in that The diaphragm comprises: a substrate; a first insulating layer coated on the substrate, the first insulating layer comprising a first part, a second part and a third part, two ends of the second part being connected to the first part and the third part respectively; a second insulating layer coated on the first part.

2. The separator according to claim 1, characterized in that The diaphragm further comprises a moisturizing layer coated on the third part.

3. The diaphragm of claim 2, wherein, The size of the first insulating layer along the length direction of the substrate is L1, and the size of the third part is L2, 1 / 7≤L2 / L1≤1 / 6.

4. The diaphragm of claim 2, wherein The sum of the thicknesses of the moisturizing layer, the third part and the substrate is A, 20μm≤A≤30μm.

5. The separator of claim 1, wherein The size of the first insulating layer along the length direction of the substrate is L1, and the size of the first part is L3, 1 / 7≤L3 / L1≤1 / 6.

6. The separator of claim 1, wherein The first insulating layer and the second insulating layer are both provided with two, one of the first insulating layer and one of the second insulating layer are located on one side of the substrate, and the other of the first insulating layer and the other of the second insulating layer are located on the other side of the substrate.

7. The separator of claim 1, wherein The thickness of the first insulating layer is B, 1.5μm≤B≤2.5μm.

8. The separator of claim 1, wherein The sum of the thicknesses of the second insulating layer, the first part and the substrate is C, 40μm≤C≤50μm.

9. An electric cell, characterized by The diaphragm comprises the diaphragm according to any one of claims 1 to 8.

10. The electric cell of claim 9, wherein, The battery cell further comprises: a positive electrode sheet; a negative electrode sheet; The diaphragm is located between the positive electrode sheet and the negative electrode sheet, the positive electrode sheet, the diaphragm and the negative electrode sheet are laminated and wound to form the battery cell, the first part is the winding end point of the battery cell, and the third part is the winding starting point of the battery cell.

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