Diaphragm, lithium ion battery and electronic equipment

Abstract

The invention relates to a diaphragm, a lithium ion battery and electronic equipment. The diaphragm comprises a diaphragm body and a first coating arranged on at least one side of the diaphragm body, wherein the first coating is used for being bonded with a part, coated with a single-sided active substance layer, of a battery pole piece; the first coating comprises a high-temperature-resistant material; and the high-temperature-resistant material accounts for 17.5-46.3% of the total mass of the first coating. In the diaphragm, the first coating comprises the high-temperature-resistant material, so that the high-temperature-resistant performance of the diaphragm can be improved, the problem of short circuit caused by contact of a cathode and an anode due to internal shrinkage of the diaphragm can be avoided when thermal runaway of the battery occurs, and the reliability of the battery is ensured. Besides, the diaphragm is bonded with the part, coated with the single-sided active substance layer, of the battery pole piece through the first coating, so that the bonding force between the diaphragm and the part, coated with the single-sided active substance layer, of the battery pole piece is improved, and the reliability and the cyclicity of the battery are further improved.

Description

Technical Field

[0001] This disclosure relates to the field of battery manufacturing technology, and more particularly to a separator, a lithium-ion battery, and an electronic device. Background Technology

[0002] As the pace of life accelerates, the demand for high energy density in mobile phones is increasing. However, with the increase in energy density, battery reliability has significantly decreased. This reliability issue is mainly due to short circuits caused by the separator shrinking during thermal runaway, leading to contact between the anode and cathode. Additionally, the interface performance of a single-sided battery is inferior to that of a double-sided battery. Summary of the Invention

[0003] To overcome the problems existing in related technologies, this disclosure provides a separator, a lithium-ion battery, and an electronic device.

[0004] According to a first aspect of the present disclosure, a separator is provided, the separator including a separator body and a first coating disposed on at least one side of the separator body, the first coating being used to bond to a portion of a battery electrode coated with a single-sided active material layer.

[0005] The first coating comprises a high-temperature resistant material; the high-temperature resistant material accounts for 17.5-46.3% of the total mass of the first coating.

[0006] In some embodiments of this disclosure, the thickness of the first coating is 0.8-5.9 μm.

[0007] In some embodiments of this disclosure, the first coating further includes an adhesive material comprising a first polymer having a particle size greater than or equal to 300 nm.

[0008] In some embodiments of this disclosure, the first polymer includes at least one selected from polyvinylidene fluoride-hexafluoropropylene copolymer, polyvinylidene fluoride-chlorotrifluoroethylene copolymer, polyvinylidene fluoride-trichloroethylene copolymer, polymethyl methacrylate, polybutyl acrylate, polyacrylonitrile, and polyvinylpyrrolidone.

[0009] In some embodiments of this disclosure, the high-temperature resistant material includes high-temperature resistant fiber material.

[0010] In some embodiments of this disclosure, the high-temperature resistant fiber material includes at least one of para-aramid and meta-aramid.

[0011] In some embodiments of this disclosure, the weight per unit area of ​​the first coating is 26.3-148.5 mg / mm². 2 ; and / or, the adhesion force between the first coating and the portion of the battery electrode coated with a single-sided active material layer is 3.8-22.1 N / m.

[0012] In some embodiments of this disclosure, the separator further includes a second coating disposed on at least one side of the separator body for bonding to the portion of the battery electrode coated with a double-sided active material layer.

[0013] In some embodiments of this disclosure, the gap between the second coating and the first coating is 0-3.5 mm.

[0014] In some embodiments of this disclosure, the second thermal shrinkage rate of the second coating after being held at 125°C to 145°C for 0.8-1.5 hours is not lower than the first thermal shrinkage rate of the first coating after being held at 125°C to 145°C for 0.8-1.5 hours.

[0015] In some embodiments of this disclosure, the first thermal shrinkage rate of the first coating after being held at 125°C to 145°C for 0.8-1.5 hours is -10.9-1.8%; and the second thermal shrinkage rate of the second coating after being held at 125°C to 145°C for 0.8-1.5 hours is 3.5-33.6%.

[0016] In some embodiments of this disclosure, the second coating comprises the first polymer and a second polymer; the particle size of the second polymer is smaller than that of the first polymer.

[0017] In some embodiments of this disclosure, the mass ratio of the first polymer to the second polymer is 1.8:1 to 11.3:1.

[0018] In some embodiments of this disclosure, the second polymer includes at least one of polyacrylic acid, methyl acrylate, ethyl acrylate, and butyl acrylate.

[0019] In some embodiments of this disclosure, the thickness of the second coating is 0.5-2.6 μm; and / or, the weight per unit area of ​​the second coating is 18.6-107.1 mg / mm². 2 ; and / or, the adhesion between the second coating and the double-sided active material layer is 1.8-11.4 N / m.

[0020] In some embodiments of this disclosure, the mass ratio of the high-temperature resistant material to the adhesive material is 1:1.3-4.6.

[0021] In some embodiments of this disclosure, the thickness of the first coating is 0.8-5.9 μm; and / or, the unit weight of the first coating is 1.7-11.2 mg / cm³. 2 .

[0022] In some embodiments of this disclosure, the high-temperature resistant material includes at least one of aluminum oxide, barium sulfate, magnesium oxide, para-aramid, meta-aramid, and nylon.

[0023] In some embodiments of this disclosure, the diaphragm further includes an adhesive layer disposed on the side of the first coating away from the diaphragm body;

[0024] The adhesive layer comprises the first polymer and the second polymer; the particle size of the first polymer is larger than that of the second polymer.

[0025] In some embodiments of this disclosure, the first polymer comprises at least one selected from polyvinylidene fluoride-hexafluoropropylene copolymer, polyvinylidene fluoride-chlorotrifluoroethylene copolymer, polyvinylidene fluoride-trichloroethylene copolymer, polymethyl methacrylate, polybutyl acrylate, polyacrylonitrile, and polyvinylpyrrolidone; and / or,

[0026] The second polymer includes at least one of polyacrylic acid, methyl acrylate, ethyl acrylate and butyl acrylate.

[0027] In some embodiments of this disclosure, the resistivity of the diaphragm is 0.2-2.1 Ω / m, and the elongation of the diaphragm is 180-300%; the ratio of the elongation to the resistivity is greater than or equal to 900.

[0028] According to a second aspect of the present disclosure, a lithium-ion battery is provided, the lithium-ion battery including the separator described above.

[0029] According to a third aspect of the present disclosure, an electronic device is provided, the electronic device comprising the lithium-ion battery described above.

[0030] According to a fourth aspect of the present disclosure, a diaphragm is provided, the diaphragm comprising:

[0031] diaphragm body;

[0032] The first coating includes a third polymer, the first melting point of which is greater than or equal to a preset threshold; the first coating is disposed on a first surface of the separator body, the first surface being used to face the positive electrode of the lithium-ion battery.

[0033] In some embodiments of this disclosure, the diaphragm further includes a second coating comprising a fourth polymer, the second melting point of which is different from the first melting point of the third polymer; the second coating is disposed between the first surface of the diaphragm body and the first coating.

[0034] In some embodiments of this disclosure, the second coating is further disposed on a second surface of the separator body, the second surface being used in the lithium-ion battery to face the negative electrode sheet of the lithium-ion battery.

[0035] In some embodiments of this disclosure, the ratio of the first melting point of the third polymer to the second melting point of the fourth polymer is 1.0-3.2.

[0036] In some embodiments of this disclosure, the preset threshold is 150 degrees; and / or, the second melting point is 78–150 degrees.

[0037] In some embodiments of this disclosure, the first average particle size Dv1(50) of the third polymer and the second average particle size Dv2(50) of the fourth polymer satisfy the following relationship:

[0038] 2.8≤Dv1(50) / Dv2(50)≤9.6.

[0039] In some embodiments of this disclosure, the third polymer comprises homopolymers and / or copolymers of at least one monomer selected from vinylidene fluoride, hexafluoropropylene, propylene, vinyl chloride, styrene, butadiene, acrylate, acrylic acid, aramid, and aromatic compounds containing benzene rings.

[0040] In some embodiments of this disclosure, the unit weight of the first coating is 0.01–1 mg / cm³. 2 ; and / or, the average molecular weight of the third polymer is 500,000 to 2,000,000; and / or, the thickness of the first coating is 0.2 to 1 μm.

[0041] In some embodiments of this disclosure, the fourth polymer comprises a homopolymer and / or copolymer of at least one monomer selected from ethylene, propylene, vinylidene fluoride, acrylic acid, acrylate, styrene, acrylonitrile, maleic anhydride, vinyl chloride, and propylene chloride.

[0042] In some embodiments of this disclosure, the unit weight of the second coating is 0.2-2 mg / cm³. 2 ; and / or, the average molecular weight of the fourth polymer is 300,000 to 500,000; and / or, the thickness of the second coating is 0.5 to 2 μm.

[0043] According to a fifth aspect of the present disclosure, a lithium-ion battery is provided, including the separator described above.

[0044] According to a sixth aspect of the present disclosure, an electronic device is provided, including the lithium-ion battery described above.

[0045] The technical solutions provided by the embodiments of this disclosure can include the following beneficial effects: In the separator provided by this disclosure, the first coating includes a high-temperature resistant material, which can improve the high-temperature resistance of the separator. Therefore, in the event of thermal runaway of the battery, the separator will not shrink inward, causing a short circuit due to contact between the cathode and anode, thus ensuring the reliability of the battery. Furthermore, the separator and the portion of the battery electrode coated with a single-sided active material layer are bonded together through the first coating, improving the adhesion between the separator and the portion of the battery electrode coated with a single-sided active material layer, further enhancing the reliability and cycle life of the battery.

[0046] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit this disclosure. Detailed Implementation

[0047] Exemplary embodiments will now be described in detail. The embodiments described below are not representative of all embodiments consistent with the present invention. Rather, they are merely examples of apparatuses and methods consistent with some aspects of the invention as detailed in the appended claims.

[0048] When batteries in electronic devices experience thermal runaway, the separator may shrink inward, causing a short circuit due to contact between the anode and cathode. Traditional solutions to this problem typically involve coating the separator surface with a ceramic coating to mitigate this shrinkage, but this still carries the risk of failure. Furthermore, the interface performance of the single-sided area of ​​the battery electrode is inferior to that of the double-sided area.

[0049] To address the aforementioned technical issues, this disclosure provides a separator whose first coating includes a high-temperature resistant material. This enhances the separator's high-temperature resistance, preventing short circuits caused by separator shrinkage leading to contact between the cathode and anode during thermal runaway, thus ensuring battery reliability. Furthermore, the first coating bonds the separator to the portion of the battery electrode coated with a single-sided active material layer, improving adhesion and further enhancing battery reliability and cycle life.

[0050] An exemplary embodiment of this disclosure provides a separator, which includes a separator body and a first coating disposed on at least one side of the separator body. The first coating is used to bond to the portion of a battery electrode coated with a single-sided active material layer. The first coating includes a high-temperature resistant material, which accounts for 17.5-46.3% of the total mass of the first coating. The first coating of the separator provided in this embodiment includes a high-temperature resistant material, thus improving the high-temperature resistance of the separator. This prevents short circuits caused by separator shrinkage leading to contact between the cathode and anode during thermal runaway, ensuring battery reliability. Furthermore, the first coating bonds the separator to the portion of the battery electrode coated with a single-sided active material layer, improving the adhesion between the separator and the portion of the battery electrode coated with a single-sided active material layer, further enhancing battery reliability and cycle life.

[0051] For example, the membrane body can be a porous substrate formed by casting or stretching one or more of polyethylene, polypropylene, and polyimide, with a pore size of 20-500 nm and a thickness of 2.7-9.8 μm.

[0052] For example, the first coating may be applied to at least one side of the diaphragm body by roller coating or spraying to form a diaphragm.

[0053] In one exemplary embodiment, the thickness of the first coating is 0.8-5.9 μm. The first coating is disposed on at least one side of the separator body for bonding to the portion of the battery electrode coated with a single-sided active material layer. The first coating includes a high-temperature resistant material, which can improve the high-temperature resistance of the separator to ensure its reliability in the event of thermal runaway. Simultaneously, the first coating can also improve the adhesion between the separator and the portion of the battery electrode coated with the single-sided active material layer, further improving the battery's reliability and cycle life. However, the thickness of the first coating should not be too large, otherwise it will increase the thickness of the separator, increasing the assembly difficulty and space required for the battery. Setting the thickness of the first coating to 0.8-5.9 μm ensures both the high-temperature resistance of the separator and the adhesion between the separator and the portion of the battery electrode coated with the single-sided active material layer without excessively increasing the separator thickness.

[0054] In one exemplary embodiment, the first coating further includes an adhesive material comprising a first polymer with a particle size greater than or equal to 300 nm. This large-particle-size polymer exhibits high adhesiveness, enabling it to bond the high-temperature resistant material to the separator body to form the first coating. Simultaneously, it improves the adhesion between the separator and the portion of the battery electrode coated with the single-sided active material layer, ensuring the reliability and cycle life of the separator. Furthermore, as a large-particle-size polymer, the first polymer also possesses high toughness and ductility. When the first coating is bonded to the innermost and outermost sides of the battery electrode, if an abnormal impact occurs to the battery, the first coating extends outwards, providing a better wrapping effect for the bare cell. This prevents the bare cell from colliding with the outer packaging film and causing a short circuit, thus ensuring battery reliability.

[0055] In one exemplary embodiment, the first polymer includes at least one selected from polyvinylidene fluoride-hexafluoropropylene copolymer, polyvinylidene fluoride-chlorotrifluoroethylene copolymer, polyvinylidene fluoride-trichloroethylene copolymer, polymethyl methacrylate, polybutyl acrylate, polyacrylonitrile, and polyvinylpyrrolidone.

[0056] In this embodiment, the first polymer is a large-particle-size polymer with high adhesiveness, capable of bonding high-temperature resistant materials to the separator body to form the first coating. It also improves the adhesion between the separator and the portion of the battery electrode coated with the single-sided active material layer, ensuring the reliability and cycle life of the separator. Furthermore, the first polymer also possesses high toughness and ductility. When the first coating is bonded to the innermost and outermost sides of the battery electrode, if the battery experiences an abnormal impact, the first coating extends outwards, providing good protection for the bare cell and preventing short circuits caused by collisions between the bare cell and the outer packaging film, thus ensuring battery reliability.

[0057] In one exemplary embodiment, the high-temperature resistant material includes a high-temperature resistant fiber material. High-temperature resistant fiber materials possess excellent properties such as ultra-high strength, high modulus, high temperature resistance, acid and alkali resistance, light weight, insulation, aging resistance, and stable chemical structure. Adding a high-temperature resistant fiber material to the first coating and disposing it on at least one side of the separator body can uniformly improve the high-temperature resistance of the separator, preventing the separator from shrinking inwards during thermal runaway of the battery.

[0058] In one exemplary embodiment, the high-temperature resistant fiber material may include at least one of para-aramid and meta-aramid. Both para-aramid and meta-aramid are excellent high-temperature resistant fibers, possessing characteristics such as high strength and high modulus, lightweight and flame retardancy, high temperature resistance, corrosion resistance, and excellent insulation properties. Using at least one of para-aramid and meta-aramid as the high-temperature resistant material to prepare the first coating, and depositing it on at least one side of the separator body, can improve the high-temperature resistance of the separator. This ensures that even if the battery experiences thermal runaway, the separator will not shrink inward, causing a short circuit due to contact between the anode and cathode, thus guaranteeing the reliability of the battery.

[0059] In one exemplary embodiment, the weight per unit area of ​​the first coating is 26.3-148.5 mg / mm². 2 The adhesion strength between the first coating and the portion of the battery electrode coated with a single-sided active material layer is 3.8-22.1 N / m. The first coating is disposed on at least one side of the separator body and adheres to the portion of the battery electrode coated with a single-sided active material layer. The first coating includes a high-temperature resistant material, which can improve the high-temperature resistance of the separator. However, the amount of the first coating on the separator body should not be excessive to avoid increasing the thickness of the first coating and the separator, thereby increasing the assembly difficulty and volume of the battery. The first coating is applied at a strength of 26.3-148.5 mg / mm². 2 The first coating, applied per unit area weight, is applied to at least one side of the separator body. This ensures that the first coating improves the high-temperature resistance and adhesion strength of the separator without excessively increasing the amount of coating on the separator body, thus guaranteeing the reliability of both the separator and the battery. Furthermore, the adhesion force between the first coating and the portion of the battery electrode coated with the single-sided active material layer can reach 3.8-22.1 N / m, effectively ensuring a tight bond between the separator and the portion of the battery electrode coated with the single-sided active material layer, further improving the battery's reliability and cycle life.

[0060] In one exemplary embodiment, the separator further includes a second coating disposed on at least one side of the separator body for bonding to the portion of the battery electrode coated with the double-sided active material layer. The second coating may be disposed on the side of the separator body closest to the battery electrode coated with the double-sided active material layer to firmly bond the separator to the portion of the battery electrode coated with the double-sided active material layer, thereby separating the cathode and anode of the battery and preventing short circuits caused by contact between the cathode and anode.

[0061] For example, the second coating may be applied to at least one side of the diaphragm body by roller coating or spraying.

[0062] In an exemplary embodiment, the gap between the second coating and the first coating is 0-3.5 mm. The first coating is disposed on the portion of the separator body near the battery electrode coated with a single-sided active material layer, and the second coating is disposed on the portion of the battery electrode coated with a double-sided active material layer. The first and second coatings may or may not overlap. When the first and second coatings do not overlap, the gap between the second and first coatings is greater than 0 and less than or equal to 3.5 mm to avoid an excessively large gap between the second and first coatings, which would result in a large separator thickness.

[0063] In an exemplary embodiment, the second thermal shrinkage rate of the second coating after being held at 125°C to 145°C for 0.8-1.5 hours is not lower than the first thermal shrinkage rate of the first coating after being held at 125°C to 145°C for 0.8-1.5 hours. The first coating includes at least one high-temperature resistant fiber selected from para-aramid and meta-aramid. Therefore, the first coating exhibits excellent thermal shrinkage at high temperatures. After being held at 125°C to 145°C for 0.8-1.5 hours, the first thermal shrinkage rate of the first coating is lower than the second thermal shrinkage rate of the second coating. This ensures that even in the event of thermal runaway in the battery, the separator will not shrink inward, leading to short circuits due to contact between the anode and cathode, thus guaranteeing battery reliability.

[0064] For example, the second thermal shrinkage rate of the second coating after being held at 130 degrees for 1 hour is not less than the first thermal shrinkage rate of the first coating after being held at 130 degrees for 1 hour.

[0065] In an exemplary embodiment, the first heat shrinkage rate of the first coating after being held at 125°C to 145°C for 0.8-1.5 hours is -10.9-1.8%, and the second heat shrinkage rate of the second coating after being held at 125°C to 145°C for 0.8-1.5 hours is 3.5-33.6%. The first coating includes at least one high-temperature resistant fiber selected from para-aramid and meta-aramid, thus exhibiting excellent heat shrinkage at high temperatures. The first heat shrinkage rate after being held at 125°C to 145°C for 0.8-1.5 hours is -10.9-1.8%, and the second heat shrinkage rate of the second coating after being held at 125°C to 145°C for 0.8-1.5 hours is 3.5-33.6%. The excellent heat shrinkage performance of the first coating at high temperatures ensures that even in the event of thermal runaway in the battery, the separator will not shrink inwards, causing short circuits due to contact between the anode and cathode, thus guaranteeing battery reliability.

[0066] For example, the first heat shrinkage rate of the first coating after being held at 130 degrees for 1 hour is -10.9-1.8%, and the second heat shrinkage rate of the second coating after being held at 130 degrees for 1 hour is 3.5-33.6%.

[0067] In one exemplary embodiment, the second coating comprises a first polymer and a second polymer, wherein the particle size of the second polymer is smaller than that of the first polymer. The first polymer has a particle size greater than or equal to 300 nm, and is a large-particle-size polymer with high adhesion. The second polymer has a smaller particle size than the first polymer, and is also a small-particle-size polymer with high adhesion. The second coating, comprising the first and second polymers, can be disposed on the side of the separator body near the battery electrode coated with a double-sided active material layer, to firmly bond the separator to the portion of the battery electrode coated with the double-sided active material layer, thereby separating the cathode and anode of the battery and preventing short circuits caused by contact between the cathode and anode.

[0068] For example, the first polymer can be coated onto at least one side of the diaphragm body by roller coating or spraying, and then the second polymer can be coated onto the layer formed by the first polymer by roller coating or spraying. Alternatively, the second polymer can be coated onto at least one side of the diaphragm body by roller coating or spraying, and then the first polymer can be coated onto the layer formed by the second polymer by roller coating or spraying.

[0069] In one exemplary embodiment, the mass ratio of the first polymer to the second polymer is 1.8:1 to 11.3:1.

[0070] The second coating comprises a first polymer and a second polymer, with a mass ratio of the first polymer to the second polymer ranging from 1.8:1 to 11.3:1. This allows the second coating to firmly bond the separator to the portion of the battery electrode coated with the double-sided active material layer with a smaller coating amount and a thinner thickness. This separates the cathode and anode of the battery, preventing the cathode and anode from coming into contact and causing a short circuit.

[0071] In one exemplary embodiment, the second polymer includes at least one of polyacrylic acid, methyl acrylate, ethyl acrylate, and butyl acrylate.

[0072] In this embodiment, the second polymer is a small-particle-size polymer with high adhesiveness, which can firmly bond the separator to the portion of the battery electrode coated with the double-sided active material layer. This allows the separator to separate the cathode and anode of the battery, preventing them from contacting each other and causing a short circuit. Furthermore, the second polymer also possesses a certain degree of toughness and ductility. When the battery experiences an abnormal impact, the second coating can extend to a certain extent, further preventing the cathode and anode from contacting each other and causing a short circuit, thus ensuring the reliability of the battery.

[0073] In one exemplary embodiment, the thickness of the second coating is 0.5-2.6 μm, and the weight per unit area of ​​the second coating is 18.6-107.1 mg / mm².2 The adhesion between the second coating and the double-sided active material layer is 1.8-11.4 N / m.

[0074] The portion of the battery electrode coated with a double-sided active material layer exhibits superior interfacial performance. Therefore, the second coating, which adheres to this portion, can achieve a tight bond between the separator and the coated portion of the battery electrode with a relatively thin thickness and a small coating amount. For example, the thickness of the second coating is 0.5-2.6 μm, and its weight per unit area is 18.6-107.1 mg / mm². 2 At this time, with a smaller amount of second coating and a thinner second coating thickness, it is possible to ensure that the separator and the part of the battery electrode coated with the double-sided active material layer are firmly bonded, so that the separator separates the cathode and anode of the battery, avoiding short circuit caused by contact between the cathode and anode of the battery, and also avoiding increasing the thickness of the separator and the assembly difficulty of the battery.

[0075] In one exemplary embodiment, the mass ratio of the high-temperature resistant material to the adhesive material is 1:1.3-4.6.

[0076] In this embodiment, the first coating includes a high-temperature resistant material and an adhesive material. The high-temperature resistant material enhances the high-temperature resistance of the separator, preventing short circuits caused by separator shrinkage leading to contact between the cathode and anode during thermal runaway, thus ensuring battery reliability. The adhesive material includes a first polymer, which is a large-particle-size polymer with high adhesiveness. This polymer adheres the high-temperature resistant material to the separator body to form the first coating and also improves the adhesion between the separator and the portion of the battery electrode coated with the single-sided active material layer, ensuring the separator's reliability and cycle life. Furthermore, as a large-particle-size polymer, the first polymer also possesses high toughness and ductility. When the first coating adheres to the innermost and outermost sides of the battery electrode, if the battery experiences an abnormal impact, the first coating extends outwards, providing good protection for the bare cell and preventing short circuits caused by collisions between the bare cell and the outer packaging film, thus ensuring battery reliability. A mass ratio of high-temperature resistant material to adhesive material of 1:1.3-4.6 can ensure the high-temperature resistance of the separator, as well as the bonding reliability between the separator and the battery electrode coated with a single-sided active material layer and the battery's impact resistance reliability.

[0077] In one exemplary embodiment, the thickness of the first coating is 0.8-5.9 μm, and the unit weight of the first coating is 1.7-11.2 mg / cm³. 2 .

[0078] The first coating is applied to at least one side of the separator body and adheres to the portion of the battery electrode coated with a single-sided active material layer. The first coating includes a high-temperature resistant material, which improves the high-temperature resistance of the separator to ensure its reliability in the event of thermal runaway. Simultaneously, the first coating enhances the adhesion between the separator and the portion of the battery electrode coated with the single-sided active material layer, further improving battery reliability and cycle life. However, the thickness of the first coating should not be too large, otherwise it will increase the thickness of the separator, increasing the assembly difficulty and space required for the battery. Setting the thickness of the first coating to 0.8-5.9 μm ensures the high-temperature resistance of the separator and the adhesion to the portion of the battery electrode coated with the single-sided active material layer without excessively increasing the separator thickness. Furthermore, the amount of the first coating applied to the separator body should not be excessive to avoid increasing the thickness of both the first coating and the separator, thereby increasing the assembly difficulty and volume of the battery. The first coating is applied at a concentration of 1.7-11.2 mg / cm³. 2 The unit area weight is coated on at least one side of the separator body, which can ensure that the first coating can improve the high temperature resistance and bonding strength of the separator without excessively increasing the amount of the first coating on the separator body, so as to ensure the reliability of the separator and the battery.

[0079] In one exemplary embodiment, the high-temperature resistant material includes at least one of aluminum oxide, barium sulfate, magnesium oxide, para-aramid, meta-aramid, and nylon.

[0080] In this embodiment, aluminum oxide, barium sulfate, magnesium oxide, para-aramid, meta-aramid, and nylon are all excellent high-temperature resistant materials, possessing characteristics such as high strength and high modulus, lightweight and flame retardancy, high temperature resistance, corrosion resistance, and excellent insulation properties. Using at least one of aluminum oxide, barium sulfate, magnesium oxide, para-aramid, meta-aramid, and nylon as the high-temperature resistant material to prepare the first coating, which is then applied to at least one side of the separator body, can improve the high-temperature resistance of the separator. This ensures that even in the event of thermal runaway, the separator will not shrink inward, causing short circuits due to contact between the anode and cathode, thus guaranteeing the reliability of the battery.

[0081] In one exemplary embodiment, the diaphragm further includes an adhesive layer disposed on the side of the first coating away from the diaphragm body. The adhesive layer includes a first polymer and a second polymer, wherein the particle size of the first polymer is larger than the particle size of the second polymer.

[0082] A first coating is provided on at least one side of the separator body, for example, on the side of the separator body near the battery electrode coated with a single-sided active material layer. This can improve the high-temperature resistance of the separator. In addition, an adhesive layer is provided on the side of the first coating away from the separator body. The adhesive layer includes a first polymer and a second polymer. The particle size of the first polymer is larger than that of the second polymer. The adhesive layer can tightly bond the separator to the part of the battery electrode coated with the single-sided active material layer, thereby improving the problems of the separator easily shrinking when the battery heats up and the poor adhesion to the part of the battery electrode coated with the single-sided active material layer.

[0083] In one exemplary embodiment, the first polymer includes at least one selected from polyvinylidene fluoride-hexafluoropropylene copolymer, polyvinylidene fluoride-chlorotrifluoroethylene copolymer, polyvinylidene fluoride-trichloroethylene copolymer, polymethyl methacrylate, polybutyl acrylate, polyacrylonitrile, and polyvinylpyrrolidone. The second polymer includes at least one selected from polyacrylic acid, methyl acrylate, ethyl acrylate, and butyl acrylate.

[0084] In this embodiment, the first polymer is a large-particle-size polymer, and the second polymer is a small-particle-size polymer, both of which have high adhesive properties. Exemplarily, the first polymer can be first applied to the side of the first coating layer away from the separator body by roller coating or spraying, and then the second polymer can be applied to the layer formed by the first polymer by roller coating or spraying to form an adhesive layer. Alternatively, the second polymer can be first applied to the side of the first coating layer away from the separator body by roller coating or spraying, and then the first polymer can be applied to the layer formed by the second polymer by roller coating or spraying to form an adhesive layer. The adhesive layer can tightly bond the separator to the portion of the battery electrode coated with a single-sided active material layer, improving the problems of the separator easily shrinking inward when the battery heats up and the poor adhesion between the separator and the portion of the battery electrode coated with a single-sided active material layer.

[0085] In one exemplary embodiment, the resistivity of the diaphragm is 0.2-2.1 Ω / m, the elongation of the diaphragm is 180-300%, and the ratio of elongation to resistivity is greater than or equal to 900.

[0086] The separator in this embodiment has a high resistivity, which can prevent short circuits between the cathode and anode in the battery. The separator has a high elongation of 180-300%, and the ratio of elongation to resistivity is greater than or equal to 900. This ensures that the battery has good ductility when subjected to mechanical damage. If the battery is subjected to abnormal impact, the separator can extend to prevent the cathode and anode from contacting and causing a short circuit, thus ensuring the reliability and safety of the battery, while also improving high-rate charging performance.

[0087] To more clearly explain the technical solutions provided by the exemplary embodiments of this disclosure, a comparison is given below between the embodiments of the diaphragm of this disclosure and the diaphragm of Comparative Example 1 by way of a list. In Examples 1-27 and Comparative Example 1, the diaphragm body is a porous substrate formed by casting and stretching one or more of polyethylene, polypropylene, and polyimide.

[0088] Table 1 Comparison of the diaphragms of Examples 1-27 with Comparative Example 1

[0089]

[0090]

[0091]

[0092] As can be seen from the comparison between the separators of Examples 1-27 in Table 1 above and Comparative Example 1, the separator provided by the exemplary embodiments of this disclosure, by providing a first coating and a second coating on at least one side of the separator body, greatly alleviates the thermal shrinkage phenomenon of the separator at high temperatures, and performs well in battery hot box tests. In contrast, the separator in Comparative Example 1 only uses the separator body, and its thermal shrinkage rate reaches 10% at 130°C, resulting in poor performance in battery hot box tests.

[0093] This disclosure provides a lithium-ion battery, including the separator provided in the above embodiments. The lithium-ion battery operates based on the principle of ion diffusion. Because the first coating of the separator provided in the above embodiments includes a high-temperature resistant material, the high-temperature resistance of the separator is improved. Therefore, even in the event of thermal runaway in the lithium-ion battery, the separator will not shrink inward, causing a short circuit due to contact between the cathode and anode, thus ensuring the reliability of the lithium-ion battery. Furthermore, the separator is bonded to the portion of the lithium-ion battery electrode coated with a single-sided active material layer through the first coating, improving the adhesion between the separator and the portion of the lithium-ion battery electrode coated with the single-sided active material layer, further enhancing the reliability and cycle life of the lithium-ion battery.

[0094] For example, a lithium-ion battery includes a cathode electrode, a separator and an anode electrode provided in the above embodiments of this disclosure, which are wound or stacked to form a bare cell, and then encapsulated in an aluminum-plastic film, injected with electrolyte, and formed to form a finished cell. The cell and a protection board form a battery and are placed in an electronic device, where a charger charges and discharges the lithium-ion battery.

[0095] For example, the separator provided in the above embodiments of this disclosure has a first coating with excellent high-temperature resistance that can be bonded to the positive electrode of a lithium-ion battery.

[0096] This disclosure provides an electronic device including the lithium-ion battery described in the above embodiments. The lithium-ion battery in this electronic device exhibits good reliability and cycle life, thereby extending the lifespan of the electronic device. In this embodiment, the electronic device includes mobile phones, tablet computers, iPads, digital broadcasting terminals, messaging devices, game consoles, medical devices, fitness equipment, personal digital assistants, smart wearable devices, smart TVs, etc.

[0097] With the fast pace of life, there is an increasing demand for faster charging speeds and longer battery life for mobile phones. However, mobile phone batteries experience significant capacity loss during fast charging, necessitating a method to improve battery safety. One related technology involves coating the positive electrode material with a heat-resistant layer to enhance battery thermal safety. However, this coating reduces the specific capacity of the positive electrode, resulting in lower overall battery energy density.

[0098] To address the above technical problems, this disclosure provides a separator, comprising a separator body and a first coating. The first coating comprises a third polymer, the third polymer having a first melting point greater than or equal to a preset threshold. The first coating is disposed on a first surface of the separator body, the first surface being positioned facing the positive electrode of the lithium-ion battery. By disposing of the first coating on the first surface of the separator body facing the positive electrode of the lithium-ion battery, and by ensuring the first coating has a high melting point, the first coating can prevent the separator from melting and breaking down at high temperatures during thermal runaway, thus avoiding short circuits caused by contact between the cathode and anode, improving battery safety performance. Furthermore, it eliminates the need to coat the positive electrode, thereby avoiding any impact on the specific capacity of the positive electrode.

[0099] In one exemplary embodiment, the diaphragm further includes a second coating comprising a fourth polymer having a second melting point different from that of a third polymer, the second coating being disposed between a first surface of the diaphragm body and the first coating.

[0100] The second melting point of the fourth polymer forming the second coating is different from the first melting point of the third polymer forming the first coating. For example, the second melting point of the fourth polymer is lower than the first melting point of the third polymer. In this way, when the battery temperature is too high, such as when thermal runaway occurs, the second coating melts and flows, blocking the pores on the separator body, preventing the exchange of lithium ions between the positive and negative electrodes, increasing the internal resistance of the battery, thereby avoiding the danger of short circuit or even explosion caused by excessive temperature and excessive current.

[0101] Therefore, the first coating with a high melting point ensures that the separator will not melt and break down at high temperatures, preventing short circuits caused by contact between the cathode and anode. The second coating with a low melting point melts and flows when the battery temperature is too high, such as during thermal runaway, blocking the pores in the separator body and preventing the exchange of lithium ions between the positive and negative electrodes. This increases the battery's internal resistance, thus avoiding the danger of short circuits or even explosions caused by excessive temperature and current. This provides a "double insurance" for battery safety at high temperatures, effectively improving the battery's safety and reliability at high temperatures.

[0102] In one exemplary embodiment, a second coating is further disposed on a second surface of the separator body, the second surface being used to face the negative electrode of the lithium-ion battery.

[0103] In addition to being disposed between the first surface of the separator body and the first coating, the second coating can also be disposed on the second surface of the separator body, facing the negative electrode of the lithium-ion battery. When the battery temperature is too high, such as in the event of thermal runaway, the second coating disposed on both sides of the separator body melts and flows on both sides of the separator body, blocking the pores on the separator body, ensuring that the exchange of lithium ions between the positive and negative electrodes is prevented, increasing the internal resistance of the battery, thereby avoiding the danger of short circuits or even explosions caused by excessive temperature and excessive current.

[0104] In one exemplary embodiment, the ratio of the first melting point of the third polymer to the second melting point of the fourth polymer is 1.0-3.2.

[0105] The second melting point of the fourth polymer is lower than the first melting point of the third polymer, meaning the first coating has a high melting point and the second coating has a low melting point. The high-melting-point first coating is applied to the first surface of the separator body, facing the positive electrode of the lithium-ion battery. In the event of thermal runaway, this high-melting-point coating ensures the separator will not melt and break at high temperatures, thus preventing short circuits caused by contact between the cathode and anode, improving battery safety. Furthermore, it eliminates the need to coat the positive electrode, avoiding any impact on its specific capacity. The low-melting-point second coating is applied between the first surface of the separator body and the first coating, or alternatively, to the second surface of the separator body. When the battery temperature becomes too high, such as during thermal runaway, the low-melting-point second coating melts and flows on both sides of the separator body, blocking the pores and preventing the exchange of lithium ions between the positive and negative electrodes. This increases the battery's internal resistance, thus avoiding the risk of short circuits or even explosions caused by excessive temperature and current. This provides a "double insurance" for battery safety at high temperatures, effectively improving the battery's safety and reliability.

[0106] After the second coating melts and flows, it blocks the pores on the separator body, preventing the exchange of lithium ions between the positive and negative electrodes. This process is irreversible; that is, once the second coating melts and blocks the pores on the separator body at high temperatures, the pore channels cannot be restored at low temperatures, rendering the battery unusable. Therefore, the melting point of the second coating should not be too low to avoid melting and flowing of the second coating when the battery temperature rises slightly. In this embodiment,

[0107] The ratio of the first melting point of the third polymer to the second melting point of the fourth polymer is in the range of 1.0-3.2. This ensures that the second coating does not melt when the battery temperature rises slightly, thus guaranteeing the battery's cycle life. However, when the battery temperature rises significantly, it melts and flows, blocking the pores on the separator body and preventing the exchange of lithium ions between the positive and negative electrodes. This increases the battery's internal resistance, thereby avoiding the danger of short circuits or even explosions caused by excessive temperature and current, and ensuring the battery's safety.

[0108] In one exemplary embodiment, the preset threshold is 150 degrees and the second melting point is 78 to 150 degrees.

[0109] A first coating is provided on the first surface of the separator body facing the positive electrode of the lithium-ion battery. The first melting point of the third polymer forming the first coating is greater than or equal to 150 degrees Celsius. That is, the first coating has a high melting point. Therefore, when the battery experiences thermal runaway, the first coating can ensure that the separator will not melt and break at high temperatures, avoiding the problem of short circuit caused by contact between the anode and cathode, thus improving the safety performance of the battery. Moreover, there is no need to cover the positive electrode, so it can also avoid the problem of affecting the specific capacity of the positive electrode.

[0110] The fourth polymer forming the second coating has a second melting point of 78–150°C, meaning the second coating has a low melting point. This low-melting-point second coating is disposed between the first surface of the separator body and the first coating, or alternatively, on the second surface of the separator body. When the battery temperature becomes too high, such as in the event of thermal runaway, the low-melting-point second coating melts and flows on both sides of the separator body, blocking the pores and preventing the exchange of lithium ions between the positive and negative electrodes. This increases the battery's internal resistance, thus avoiding the risk of short circuits or even explosions caused by excessive temperature and current. The combination of the first and second coatings provides "double insurance" for battery safety at high temperatures, effectively improving the battery's safety and reliability at high temperatures.

[0111] In an exemplary embodiment, the first average particle size of the third polymer is 0.5–2 μm, and the second average particle size of the fourth polymer is 0.1–1 μm. That is, compared to the fourth polymer, the third polymer is a large-particle-size polymer, and the fourth polymer is a small-particle-size polymer. Correspondingly, the third polymer has a higher first melting point, i.e., a first melting point greater than or equal to 150°C, while the fourth polymer has a lower second melting point, i.e., a second melting point of 78–150°C. A first coating is formed on the first surface of the separator body facing the positive electrode of the lithium-ion battery. The first melting point of the third polymer forming the first coating is greater than or equal to 150°C, meaning the first coating has a high melting point. Therefore, in the event of thermal runaway, the first coating can ensure that the separator does not melt and break at high temperatures, avoiding short circuits caused by contact between the cathode and anode, thus improving battery safety performance. Furthermore, it eliminates the need to coat the positive electrode, thereby avoiding any impact on the specific capacity of the positive electrode. The fourth polymer forming the second coating has a second melting point of 78–150°C, meaning the second coating has a low melting point. This low-melting-point second coating is disposed between the first surface of the separator body and the first coating, or alternatively, on the second surface of the separator body. When the battery temperature becomes too high, such as in the event of thermal runaway, the low-melting-point second coating melts and flows on both sides of the separator body, blocking the pores and preventing the exchange of lithium ions between the positive and negative electrodes. This increases the battery's internal resistance, thus avoiding the risk of short circuits or even explosions caused by excessive temperature and current. The combination of the first and second coatings provides "double insurance" for battery safety at high temperatures, effectively improving the battery's safety and reliability at high temperatures.

[0112] In an exemplary embodiment, the first average particle size Dv1(50) of the third polymer and the second average particle size Dv2(50) of the fourth polymer satisfy the following relationship:

[0113] 2.8≤Dv1(50) / Dv2(50)≤9.6.

[0114] The first average particle size Dv1(50) of the third polymer is greater than the second average particle size Dv2(50) of the fourth polymer, and the ratio of the first average particle size Dv1(50) of the third polymer to the second average particle size Dv2(50) of the fourth polymer satisfies 2.8≤Dv1(50) / Dv2(50)≤9.6. Within this ratio range, and considering the specific types and components of the third and fourth polymers, the difference in melting point between the third and fourth polymers can be achieved accordingly. The third polymer has a higher first melting point, that is, a first melting point greater than or equal to 150 degrees Celsius, and the fourth polymer has a lower second melting point, that is, a second melting point of 78 to 150 degrees Celsius. A first coating is formed on the first surface of the separator body facing the positive electrode of the lithium-ion battery. The first melting point of the third polymer forming the first coating is greater than or equal to 150 degrees Celsius. This high melting point ensures that the separator will not melt and break down at high temperatures during thermal runaway, preventing short circuits caused by contact between the positive and negative electrodes and improving battery safety. Furthermore, it eliminates the need to coat the positive electrode, thus avoiding any impact on its specific capacity. The second melting point of the fourth polymer forming the second coating is 78–150 degrees Celsius. This low melting point second coating is positioned between the first surface of the separator body and the first coating, or it can be positioned on the second surface of the separator body. When the battery temperature becomes too high, such as during thermal runaway, the low melting point second coating melts and flows on both sides of the separator body, blocking the pores and preventing the exchange of lithium ions between the positive and negative electrodes. This increases the battery's internal resistance, thus preventing short circuits or even explosions caused by excessive temperature and current. The first and second coatings provide "double protection" for the battery's safety at high temperatures, effectively improving the battery's safety and reliability at high temperatures.

[0115] In one exemplary embodiment, the third polymer comprises homopolymers and / or copolymers of at least one monomer selected from vinylidene fluoride, hexafluoropropylene, propylene, vinyl chloride, styrene, butadiene, acrylate, acrylic acid, aramid, and benzene ring-containing aromatic compounds.

[0116] In this embodiment, the third polymer is a polymer with a relatively large first average particle size, which has a high first melting point and good adhesion. Exemplarily, the third polymer can be coated onto the first surface of the separator body by roller coating or spraying, facing the positive electrode of the lithium-ion battery, to form a first coating. This first coating has a correspondingly high melting point and good adhesion, enabling it to firmly adhere to the first surface of the separator body. In the event of thermal runaway, the high melting point of the first coating ensures that the separator will not melt and break at high temperatures, thus preventing short circuits caused by contact between the cathode and anode, improving battery safety performance. Furthermore, it eliminates the need to coat the positive electrode, thereby avoiding any impact on the specific capacity of the positive electrode.

[0117] For example, the first polymer can be coated on the side of the first coating away from the membrane body by roller coating or spraying, and then the second polymer can be coated on the layer formed by the first polymer by roller coating or spraying to form an adhesive layer.

[0118] In one exemplary embodiment, the unit weight of the first coating is 0.01–1 mg / cm³. 2 The average molecular weight of the third polymer is 500,000 to 2,000,000, and the thickness of the first coating is 0.2 to 1 μm.

[0119] The third polymer has a larger first average particle size than the fourth polymer's second average particle size, and also has a higher average molecular weight, resulting in a higher first melting point (greater than or equal to 150 degrees Celsius). Furthermore, the third polymer exhibits better adhesion. Applying a smaller amount of the first coating to the first surface of the separator body facing the positive electrode of the lithium-ion battery, forming a thinner first coating, ensures the separator's reliability under high-temperature conditions. That is, in the event of thermal runaway, the first coating prevents the separator from melting and breaking down at high temperatures, avoiding short circuits caused by contact between the cathode and anode, thus improving battery safety. Moreover, it eliminates the need to coat the positive electrode, thereby avoiding any impact on the positive electrode's specific capacity.

[0120] In one exemplary embodiment, the fourth polymer comprises a homopolymer and / or copolymer of at least one monomer selected from ethylene, propylene, vinylidene fluoride, acrylic acid, acrylate, styrene, acrylonitrile, maleic anhydride, vinyl chloride, and propylene chloride.

[0121] In this embodiment, the fourth polymer is a polymer with a relatively small average particle size, which has a low first melting point and adhesiveness. Exemplarily, the fourth polymer can be coated onto the first surface of the separator body by roller coating or spraying to form a second coating, and then a third polymer can be coated onto the second coating by roller coating or spraying to form a first coating; alternatively, the fourth polymer can also be coated onto the second surface of the separator body by roller coating or spraying to form a second coating. When the battery temperature is too high, such as in the event of thermal runaway, the low-melting-point second coating melts and flows on both sides of the separator body, blocking the pores on the separator body and ensuring that lithium ions are prevented from exchanging between the positive and negative electrodes. This increases the internal resistance of the battery, thereby avoiding the danger of short circuits or even explosions caused by excessive temperature and current.

[0122] In one exemplary embodiment, the unit weight of the second coating is 0.2-2 mg / cm³. 2 The average molecular weight of the fourth polymer is 300,000 to 500,000, and the thickness of the second coating is 0.5 to 2 μm.

[0123] The fourth polymer has a smaller first average particle size than the third polymer, and the third polymer also has a smaller average molecular weight, which results in a lower first melting point, specifically a second melting point of 78–150°C. Furthermore, the fourth polymer exhibits good adhesion, allowing it to be coated with a 0.2–2 mg / cm³ coating on the first surface of the separator body and the first coating, or also on the second surface of the separator body facing the first surface of the positive electrode of the lithium-ion battery. 2 The second coating, with a thickness of 0.5-2 μm, can melt and flow on both sides of the separator body when the battery temperature is too high, such as when thermal runaway occurs. This generates more molten fluid to block the pores on the separator body, ensuring that the exchange of lithium ions between the positive and negative electrodes is prevented. This increases the internal resistance of the battery, thereby avoiding the danger of short circuits or even explosions caused by excessive temperature and current.

[0124] To more clearly explain the technical solutions provided by the exemplary embodiments of this disclosure, a comparison is given below between the embodiments of the diaphragm of this disclosure and the diaphragm of Comparative Example 1 by way of a list. In Examples 28-50 and Comparative Example 2, the diaphragm body is a porous substrate formed by casting and stretching one or more of polyethylene, polypropylene, and polyimide.

[0125] Table 2 Comparison of the diaphragms of Examples 28-50 with Comparative Example 2

[0126]

[0127]

[0128] As can be seen from the comparison between the separators of Examples 28-50 in Table 1 above and Comparative Example 2, the separator provided by the exemplary embodiments of this disclosure, by providing a first coating and a second coating on at least one side of the separator body, greatly alleviates the thermal shrinkage phenomenon of the separator at high temperatures, and performs well in battery hot box tests. In contrast, the separator in Comparative Example 1 only uses the separator body, and its thermal shrinkage rate reaches 10% at 130°C, resulting in poor performance in battery hot box tests.

[0129] This disclosure provides a lithium-ion battery, including the separator provided in the above embodiments. The lithium-ion battery operates based on the principle of ion diffusion. Because the separator provided in the above embodiments of this disclosure has a first coating on the first surface of the separator body facing the positive electrode of the lithium-ion battery, and this first coating has a high melting point, in the event of thermal runaway, the first coating can ensure that the separator will not melt and break at high temperatures, avoiding the problem of short circuits caused by contact between the cathode and anode, thus improving the battery's safety performance. Furthermore, it eliminates the need to coat the positive electrode, thereby avoiding the problem of affecting the specific capacity of the positive electrode.

[0130] For example, the lithium-ion battery can be a pouch battery or a steel-cased battery.

[0131] Exemplary, a lithium-ion battery includes a separator, a positive electrode, and a negative electrode as provided in the above embodiments of this disclosure. A bare cell is formed by winding or stacking these components, and a finished cell is prepared by liquid injection / formation / molding. The fully charged voltage of the cell is not less than 4.5V. The positive electrode may include a positive active material, including at least one of lithium cobalt oxide, lithium nickel cobalt aluminum oxide, lithium nickel cobalt manganese oxide, lithium iron phosphate, and their respective modified compounds. Modification includes doping modification, surface coating modification, or simultaneous doping and coating modification. The negative electrode may include a negative active material, including at least one of graphite and silicon-based materials.

[0132] For example, the separator provided in the above embodiments of this disclosure has a first coating with a high melting point that can be bonded to the positive electrode of a lithium-ion battery.

[0133] This disclosure provides an electronic device including the lithium-ion battery described in the above embodiments. The lithium-ion battery in this electronic device exhibits good reliability and cycle life, thereby extending the lifespan of the electronic device. In this embodiment, the electronic device includes mobile phones, tablet computers, iPads, digital broadcasting terminals, messaging devices, game consoles, medical devices, fitness equipment, personal digital assistants, smart wearable devices, smart TVs, etc.

[0134] Other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of the invention are indicated by the following claims.

[0135] It should be understood that the present invention is not limited to the precise structure described above, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

Claims

1. A diaphragm, characterized in that, The separator includes a separator body and a first coating disposed on at least one side of the separator body. The first coating is used to bond to the portion of the battery electrode coated with a single-sided active material layer. The first coating comprises a high-temperature resistant material; the high-temperature resistant material accounts for 17.5-46.3% of the total mass of the first coating.

2. The diaphragm according to claim 1, characterized in that, The thickness of the first coating is 0.8-5.9 μm.

3. The diaphragm according to claim 1, characterized in that, The first coating further includes an adhesive material comprising a first polymer having a particle size greater than or equal to 300 nm.

4. The diaphragm according to any one of claims 1-3, characterized in that, The high-temperature resistant material includes high-temperature resistant fiber material; The high-temperature resistant fiber material includes at least one of para-aramid and meta-aramid.

5. The diaphragm according to claim 4, characterized in that, The weight per unit area of ​​the first coating is 26.3-148.5 mg / mm². 2 ; and / or, the adhesion force between the first coating and the portion of the battery electrode coated with a single-sided active material layer is 3.8-22.1 N / m.

6. The diaphragm according to claim 4, characterized in that, The separator further includes a second coating, which is disposed on at least one side of the separator body for bonding to the portion of the battery electrode coated with a double-sided active material layer.

7. The diaphragm according to claim 6, characterized in that, The second heat shrinkage rate of the second coating after being held at 125°C to 145°C for 0.8-1.5 hours is not less than the first heat shrinkage rate of the first coating after being held at 125°C to 145°C for 0.8-1.5 hours; and / or The first heat shrinkage rate of the first coating after being held at 125°C to 145°C for 0.8-1.5 hours is -10.9-1.8%; the second heat shrinkage rate of the second coating after being held at 125°C to 145°C for 0.8-1.5 hours is 3.5-33.6%.

8. The diaphragm according to claim 6, characterized in that, The second coating comprises the first polymer and the second polymer; The particle size of the second polymer is smaller than that of the first polymer; and / or The mass ratio of the first polymer to the second polymer is 1.8:1 to 11.3:

1.

9. The diaphragm according to claim 6, characterized in that, The thickness of the second coating is 0.5-2.6 μm; and / or, the weight per unit area of ​​the second coating is 18.6-107.1 mg / mm². 2 ; and / or, the adhesion force between the second coating and the double-sided active material layer is 1.8-11.4 N / m.

10. The diaphragm according to claim 3, characterized in that, The mass ratio of the high-temperature resistant material to the adhesive material is 1:1.3-4.

6.

11. The diaphragm according to claim 10, characterized in that, The diaphragm further includes an adhesive layer disposed on the side of the first coating away from the diaphragm body; The adhesive layer comprises the first polymer and the second polymer; the particle size of the first polymer is larger than that of the second polymer.

12. A lithium-ion battery, characterized in that, The lithium-ion battery includes the separator according to any one of claims 1-11.

13. An electronic device, characterized in that, The electronic device includes the lithium-ion battery of claim 12.

14. A diaphragm, characterized in that, The diaphragm includes: diaphragm body; The first coating includes a third polymer, the first melting point of which is greater than or equal to a preset threshold; the first coating is disposed on a first surface of the separator body, the first surface being used to face the positive electrode of the lithium-ion battery.

15. The diaphragm according to claim 14, characterized in that, The diaphragm further includes a second coating comprising a fourth polymer, the second melting point of which is different from the first melting point of the third polymer; the second coating is disposed between the first surface of the diaphragm body and the first coating.

16. The diaphragm according to claim 15, characterized in that, The ratio of the first melting point of the third polymer to the second melting point of the fourth polymer is 1.0-3.

2.

17. The diaphragm according to claim 15, characterized in that, The first average particle size Dv1(50) of the third polymer and the second average particle size Dv2(50) of the fourth polymer satisfy the following relationship: 2.8≤Dv1(50) / Dv2(50)≤9.

6.

18. The diaphragm according to claim 15, characterized in that, The unit weight of the first coating is 0.01–1 mg / cm³. 2 ; and / or, the average molecular weight of the third polymer is 500,000 to 2,000,000; and / or, the thickness of the first coating is 0.2 to 1 μm; and / or The second coating has a unit weight of 0.2-2 mg / cm³. 2 ; and / or, the average molecular weight of the fourth polymer is 300,000 to 500,000; and / or, the thickness of the second coating is 0.5 to 2 μm.

19. A lithium-ion battery, characterized in that, Includes the diaphragm according to any one of claims 14-18.

20. An electronic device, characterized in that, Including the lithium-ion battery of claim 19.

Images