WO2025035243A1 - 隔离膜、二次电池、电化学装置和用电装置 - Google Patents

隔离膜、二次电池、电化学装置和用电装置 Download PDF

Info

Publication number
WO2025035243A1
WO2025035243A1 PCT/CN2023/112469 CN2023112469W WO2025035243A1 WO 2025035243 A1 WO2025035243 A1 WO 2025035243A1 CN 2023112469 W CN2023112469 W CN 2023112469W WO 2025035243 A1 WO2025035243 A1 WO 2025035243A1
Authority
WO
WIPO (PCT)
Prior art keywords
polymer
electrode sheet
organic coating
positive electrode
isolation
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
PCT/CN2023/112469
Other languages
English (en)
French (fr)
Inventor
樊晓贺
魏增斌
陶兴华
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Ningde Amperex Technology Ltd
Original Assignee
Ningde Amperex Technology Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Ningde Amperex Technology Ltd filed Critical Ningde Amperex Technology Ltd
Priority to CN202380036692.2A priority Critical patent/CN119072820A/zh
Priority to PCT/CN2023/112469 priority patent/WO2025035243A1/zh
Publication of WO2025035243A1 publication Critical patent/WO2025035243A1/zh
Anticipated expiration legal-status Critical
Pending legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/411—Organic material
    • H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/449—Separators, membranes or diaphragms characterised by the material having a layered structure
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/46—Separators, membranes or diaphragms characterised by their combination with electrodes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present application relates to a separator, a secondary battery and an electrochemical device containing the separator, and an electrical device containing the secondary battery or the electrochemical device.
  • the rapid increase in battery cell charge rate and the increase in battery cell energy density are not conducive to the improvement of the hot box window of the battery cell (the safe temperature at which the battery cell can be placed in a hot box for testing after charging without catching fire, exploding or smoking).
  • the hot box window of the battery cell the safe temperature at which the battery cell can be placed in a hot box for testing after charging without catching fire, exploding or smoking.
  • two methods are usually used: adjusting the solvent system of the electrolyte; or using a polyvinylidene fluoride coating with low adhesion properties to coat the isolation membrane.
  • the adjustment of the electrolyte system will deteriorate the cycle performance of the battery cell, and there is a risk of deterioration in the low-temperature performance of the battery cell; and the use of a polyvinylidene fluoride coating with too low adhesion can easily cause deformation of the battery cell and deteriorate the high-temperature storage performance of the battery cell.
  • an isolation film comprising:
  • An organic coating layer disposed on a surface of the base film, the organic coating layer comprising a first polymer and a second polymer;
  • the melting point T of the first polymer satisfies 60°C ⁇ T ⁇ 100°C;
  • the swelling degree D of the second polymer when placed in an electrolyte at 60° C. for 24 hours is ⁇ 30%, and the mass ratio of lithium hexafluorophosphate, ethylene carbonate, diethyl carbonate, propylene carbonate and propyl propionate in the electrolyte is 8.7:20:30:20:30.
  • the first polymer can maintain the adhesion requirements during the battery charge and discharge cycle, and can also improve the high-temperature storage performance; when the battery generates heat during charge and discharge, the low-melting-point first polymer is more likely to soften, and the adhesion is significantly reduced, so that the interface between the isolation membrane and the battery electrode (positive electrode) is opened, which helps to reduce heat accumulation and improve the safety performance of the battery cell hot box; the second polymer has a low swelling degree D and can maintain its original morphology in the battery cell, will not block the pores of the base film, and can effectively improve the problem of melting and film formation of the low-melting-point first polymer during the hot pressing process of the battery cell, thereby improving the cycle performance of the battery cell.
  • the weight percentage of the first polymer is greater than or equal to 40% and less than or equal to 95%, and the weight percentage of the second polymer is less than or equal to 50%.
  • the present application improves the hot box test window of the battery cell while ensuring the performance of the battery cell by reasonably formulating the ratio of the first polymer to the second polymer.
  • the higher the content of the first polymer the better the high-temperature failure effect, but if the content is too high, the isolation membrane is prone to blockage, resulting in a decrease in the dynamics of the battery cell and poor cycle performance;
  • the higher the content of the second polymer the better the cycle performance of the battery cell, but if the content is too high, the adhesion of the isolation membrane at room temperature is too low, which is easy to cause poor high-temperature storage performance, and the battery cell is at risk of deformation, which will lead to a decrease in cycle performance.
  • the weight percentage of the first polymer is greater than or equal to 60% and less than or equal to 95%, and the weight percentage of the second polymer is less than or equal to 30%.
  • the hot box test pass rate can be improved while ensuring the performance of the battery cell.
  • the median particle size Dv50 of the first polymer satisfies 1.0 ⁇ m ⁇ Dv50 ⁇ 2 ⁇ m.
  • the adhesion of the organic coating will deteriorate and the thickness will increase, resulting in a lower volume energy density of the battery cell; when the particle size of the first polymer is too small, the isolation membrane will be blocked, resulting in poor cycle performance of the battery.
  • the adhesion and appropriate thickness of the organic coating can be ensured.
  • the melting point T of the first polymer satisfies 60°C ⁇ T ⁇ 85°C.
  • the second polymer is spherical or quasi-spherical, and the sphericity R of the second polymer satisfies 0.7 ⁇ R ⁇ 1.
  • the second polymer is spherical or quasi-spherical, and the sphericity R of the second polymer satisfies 0.8 ⁇ R ⁇ 1.
  • the second polymer has a high sphericity, which can achieve better results with a smaller amount of the second polymer.
  • the spherical or quasi-spherical second polymer has a lower packing density in the organic coating, which can increase the porosity of the organic coating and improve the cycle performance of the battery cell.
  • the swelling degree D of the second polymer when placed in an electrolyte at 85° C. for 24 hours satisfies 10% ⁇ D ⁇ 50%.
  • the second polymer when the isolation membrane is applied to the battery cell, even if the temperature rises, the second polymer can better maintain the original morphology, and the second polymer has a higher melting point than the first polymer, for example, the melting point is higher than 130°C, and can maintain the original morphology in the battery cell, and will not block the pores of the base film, and can effectively improve the problem of melting and film formation of the low-melting-point first polymer during the hot pressing process of the battery cell, and improve the cycle performance of the battery cell.
  • the selection of substances with different swelling degrees is achieved by selecting different types of substances, molecular weights or different crosslinking degrees.
  • the first polymer includes a graft copolymer
  • the monomer of the polymer body in the graft copolymer includes at least one of ethylene, propylene, vinylidene fluoride, acrylic acid, acrylate, styrene, acrylonitrile, maleic anhydride, vinyl chloride and allyl chloride
  • the monomer used for grafting includes at least one of maleic anhydride, acrylate and acrylic acid
  • the weight percentage of the graft copolymer in the first polymer is greater than or equal to 3% and less than or equal to 10%.
  • the second polymer includes a polymer of at least one monomer selected from the group consisting of vinylidene fluoride, hexafluoropropylene, propylene, vinyl chloride, styrene, butadiene, acrylate, and acrylic acid, and the second polymer is at least one of a homopolymer, a copolymer, and a blended polymer.
  • the present application provides a secondary battery, which includes a positive electrode sheet, a negative electrode sheet, and the above-mentioned isolation film arranged between the positive electrode sheet and the negative electrode sheet, wherein the organic coating is located between the positive electrode sheet and the base film.
  • the present application provides an electrochemical device, which includes a positive electrode sheet, a negative electrode sheet, and the above-mentioned isolation membrane arranged between the positive electrode sheet and the negative electrode sheet, wherein the organic coating is located between the positive electrode sheet and the base film.
  • the present application provides an electrical device, the secondary battery or the electrochemical device mentioned above.
  • FIG. 1 is a schematic structural diagram of an isolation membrane according to an embodiment of the present application.
  • FIG. 2 is a schematic diagram of the working mechanism of the isolation membrane according to one embodiment of the present application.
  • the separator is a very critical part of the battery. It is a layer of separator material set between the positive and negative electrodes of the battery, which has a direct impact on the safety performance and cost of the battery.
  • the main function of the separator is to isolate the positive and negative electrodes and prevent the electrons in the battery from passing freely, while allowing the ions in the electrolyte to pass freely.
  • the present application provides a separator for a secondary battery, which can effectively improve the thermal box window of the battery cell and enhance the safety performance of the cell.
  • the separator 10 includes a base film 11 and an organic coating 13 disposed on a surface of the base film 11.
  • the side of the separator 10 having the organic coating 13 faces the positive electrode sheet 20.
  • the organic coating 13 contains a first polymer and a second polymer.
  • the present application has no particular restrictions on the type of base film 11, as long as the purpose of the present application can be achieved.
  • the base film 11 may be a resin, glass fiber, inorganic material, etc. formed by a material that is stable to the electrolyte.
  • the base film 11 includes a porous sheet or a non-woven fabric-like material with excellent liquid retention.
  • materials for the resin or glass fiber separator base film may include, but are not limited to, polyolefins, aromatic polyamides, polytetrafluoroethylene, polyether sulfone, etc. Taking polyolefins as an example, the material of the base film 11 may be selected from one or more of polypropylene and polyethylene.
  • the present application does not limit the thickness of the base film 11 as long as the purpose of the present application can be achieved.
  • the thickness of the base film 11 can be 5 to 50 ⁇ m, preferably 5 to 30 ⁇ m.
  • the melting point T of the first polymer is relatively low, 60° C. ⁇ T ⁇ 100° C. Further, in some embodiments, the melting point T of the first polymer satisfies 60° C. ⁇ T ⁇ 85° C.
  • the first polymer provides the viscosity of the organic coating 13. At a temperature below the melting point (e.g., room temperature), the first polymer has high bonding properties, can maintain the bonding force requirements during the battery charge and discharge cycle, and can also improve the high-temperature storage performance of the battery.
  • the present application selects a first polymer with a low melting point so that when the battery is charged and discharged and generates heat, for example, when the temperature rises to the melting point T or above, the first polymer with a low melting point is more likely to soften and produce fluidity, and the bonding force is significantly reduced, so that the interface between the isolation membrane and the positive electrode plate is opened, which helps to reduce heat accumulation and improve the safety performance of the battery cell hot box.
  • the median particle size Dv50 of the first polymer satisfies 0.8 ⁇ m ⁇ Dv50 ⁇ 2 ⁇ m.
  • the median particle size Dv50 of the first polymer satisfies 1.0 ⁇ m ⁇ Dv50 ⁇ 2 ⁇ m.
  • the electrolyte When the separator 10 is used in a battery, the electrolyte will penetrate into the porous separator 10, and the organic coating is also equivalent to being immersed in the electrolyte.
  • the swelling degree D of the second polymer in the electrolyte at 60° C. for 24 hours is ⁇ 30%, and the mass ratio of lithium hexafluorophosphate, ethylene carbonate, diethyl carbonate, propylene carbonate, and propyl propionate in the electrolyte is 8.7:20:30:20:30.
  • the swelling degree of the second polymer when placed in an electrolyte at 85°C for 24 hours is 10% ⁇ D ⁇ 50%.
  • the definition of swelling degree is: when the polymer molecules adsorb solvent molecules to reach swelling equilibrium, the ratio of the volume after swelling to the volume before swelling minus 1.
  • the swelling degree of a polymer is related to the polymer material composition, molecular weight, length of the molecular chain, and the degree of cross-linking of the molecular chain. The present application can ensure the swelling degree of the second polymer by selecting appropriate material composition, large molecular weight, long molecular chain or a large degree of cross-linking of the molecular chain.
  • the present application selects a second polymer with high strength and low swelling degree, so that when the isolation film 10 is applied to the battery cell, the second polymer can also maintain its original morphology.
  • the second polymer has a higher melting point than the first polymer, for example, a melting point higher than 130°C, and can maintain its original morphology in the battery cell without blocking the pores of the base film 11. It can effectively improve the problem of melting and forming a film of the first polymer with a low melting point during the hot pressing process of the battery cell, and improve the cycle performance of the battery cell.
  • the second polymer is spherical or quasi-spherical in the isolation membrane 10, and the sphericity R of the second polymer satisfies 0.7 ⁇ R ⁇ 1.0. Further, in some embodiments, the sphericity R of the second polymer satisfies 0.8 ⁇ R ⁇ 1.0.
  • the high sphericity of the second polymer can make the amount of the second polymer in the organic coating 13 less and achieve better results, and the spherical or quasi-spherical second polymer has a low stacking density in the organic coating 13, which can increase the porosity of the organic coating and improve the cycle performance of the battery cell.
  • the first polymer is more likely to soften and lose its adhesiveness, while the second polymer, due to its relatively high melting point, does not soften and remains in its rigid granular form.
  • the higher the content of the second polymer the better the cycle performance of the battery cell, but if the content is too high, the adhesion of the isolation film at room temperature will be worse, which will easily lead to poor high-temperature storage performance and the risk of deformation during circulation.
  • the weight percentage of the first polymer is greater than or equal to 40% and less than or equal to 95%, and the weight percentage of the second polymer is less than or equal to 50%. Furthermore, in some embodiments, in the organic coating 13, the weight percentage of the first polymer is greater than or equal to 60% and less than or equal to 95%, and the weight percentage of the second polymer is less than or equal to 30%.
  • the weight percentage of the second polymer is greater than or equal to 10%.
  • the weight percentage of linear carboxylic acid ester in the electrolyte is H, where 10% ⁇ H ⁇ 50%.
  • the upper limit window of the hot box test can be improved while ensuring the performance of the battery cell.
  • the first polymer has a Dv10 that satisfies 0.1 ⁇ m ⁇ Dv10 ⁇ 0.7 ⁇ m, and a Dv90 that satisfies 2 ⁇ m ⁇ Dv90 ⁇ 5 ⁇ m.
  • the Dv10 of the second polymer satisfies 0.1 ⁇ m ⁇ Dv10 ⁇ 0.5 ⁇ m
  • the Dv50 satisfies 0.5 ⁇ m ⁇ Dv50 ⁇ 2 ⁇ m
  • the Dv90 satisfies 2 ⁇ m ⁇ Dv90 ⁇ 5 ⁇ m.
  • the ratio S of the Dv90 of the second polymer to the Dv90 of the first polymer satisfies 0.6 ⁇ S ⁇ 1.0.
  • the first polymer includes a polymer of at least one monomer selected from the group consisting of ethylene, propylene, vinylidene fluoride, acrylic acid, acrylic ester, styrene, acrylonitrile, maleic anhydride, vinyl chloride and allyl chloride.
  • the first polymer is at least one selected from the group consisting of a homopolymer, a copolymer and a blended polymer.
  • the first polymer includes a grafted copolymer
  • the monomer of the polymer body in the grafted copolymer includes at least one of ethylene, propylene, vinylidene fluoride, acrylic acid, acrylate, styrene, acrylonitrile, maleic anhydride, vinyl chloride and allyl chloride
  • the monomer used for grafting includes at least one of maleic anhydride, acrylate and acrylic acid.
  • the weight percentage of the graft copolymer in the first polymer is greater than or equal to 3% and less than or equal to 10%.
  • the second polymer includes a polymer of at least one monomer selected from vinylidene fluoride, hexafluoropropylene, propylene, vinyl chloride, styrene, butadiene, acrylate, and acrylic acid, and the second polymer is at least one of a homopolymer, a copolymer, and a blended polymer.
  • the average molecular weight of the first polymer is greater than or equal to 300,000 and less than or equal to 1,000,000.
  • the average molecular weight of the second polymer is greater than or equal to 800,000 and less than or equal to 2,000,000.
  • the organic coating contains, in addition to the first polymer and the second polymer, an auxiliary component, and the weight percentage of the auxiliary component in the organic coating does not exceed 10%.
  • the auxiliary component may include conventional thickeners and wetting agents, etc.
  • the thickener may be sodium carboxymethyl cellulose or lithium carboxymethyl cellulose, and the weight percentage in the organic coating may be 0.5% to 1.5%.
  • the wetting agent includes sulfonate and dimethyl silane, and the weight percentage in the organic coating may be 1% to 10%.
  • the coating weight of the organic coating on the base film is greater than or equal to 0.5 mg/5000 mm 2 and less than or equal to 3 mg/5000 mm 2.
  • the coating thickness of the organic coating is greater than or equal to 0.5 ⁇ m and less than or equal to 5 ⁇ m.
  • the coating weight of the organic coating on the base film is greater than or equal to 0.5 mg/5000 mm 2 and less than or equal to 1.5 mg/5000 mm 2 .
  • the isolation film 10 further includes an inorganic coating 15 disposed between the base film 11 and the organic coating 13.
  • the inorganic coating 15 is used to improve the heat resistance and mechanical strength of the isolation film 10.
  • the inorganic coating 15 includes ceramics, and the ceramics include at least one of aluminum oxide, boehmite, titanium dioxide, silicon dioxide, zirconium dioxide, tin dioxide, magnesium hydroxide, magnesium oxide, zinc oxide, barium sulfate, boron nitride or aluminum nitride.
  • the separator 10 also includes another organic coating 17 disposed on the other surface of the base film 11.
  • the other organic coating 17 and the above-mentioned organic coating 13 are respectively disposed on the opposite surface of the base film 11, that is, the other organic coating 17 is disposed on the surface of the base film 11 facing the negative electrode plate 30.
  • the present application has no particular restrictions on the type of other organic coating 17, as long as it can play the role of bonding the separator and the negative electrode.
  • the other organic coating 17 mainly contains a binder and a thickener.
  • the present application also provides an electrochemical device, including a positive electrode sheet 20, a negative electrode sheet 30, an electrolyte, and the above-mentioned separator 10 disposed between the positive electrode sheet 20 and the negative electrode sheet 30.
  • the organic coating 13 is disposed on the surface of the base film 11 facing the positive electrode sheet 20, that is, located between the positive electrode sheet 20 and the base film 11, and can be used to bond the positive electrode sheet 20 and the separator 10.
  • the electrochemical device can be a secondary battery.
  • the electrolyte penetrates into the separator 10. As shown in FIG. 2 , the separator 10 does not show bonding between the positive electrode sheet 20 and the negative electrode sheet 30.
  • the positive electrode sheet, the negative electrode sheet, and the electrolyte of the electrochemical device can all be of the types known in the art.
  • the positive electrode sheet includes a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector.
  • the positive electrode current collector has two opposite surfaces along its own thickness direction, and the positive electrode film layer is disposed on any one or both of the two opposite surfaces of the positive electrode current collector.
  • the positive electrode film layer includes a positive electrode active material.
  • the positive electrode current collector may be a metal foil or a composite current collector.
  • aluminum foil may be used as the metal foil.
  • the composite current collector may include a polymer material base and a metal layer formed on at least one surface of the polymer material base.
  • the composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
  • PP polypropylene
  • PET polyethylene terephthalate
  • PBT polybutylene terephthalate
  • PS polystyrene
  • PE polyethylene
  • the positive electrode active material may be a positive electrode active material for a battery known in the art.
  • the positive electrode active material may include one or more of the following materials: lithium-containing phosphates with an olivine structure, lithium transition metal oxides, and their respective modified compounds.
  • the present application is not limited to these materials, and other traditional materials that can be used as positive electrode active materials for batteries may also be used. These positive electrode active materials may be used alone or in combination of two or more.
  • lithium transition metal oxides include, but are not limited to, lithium cobalt oxide (such as LiCoO 2 ), lithium nickel oxide (such as LiNiO 2 ), lithium manganese oxide (such as LiMnO 2 , LiMn 2 O 4 ), 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 O 2 (also referred to as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O 2 (also referred to as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O 2 (also referred to as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O 2 (also referred to as NCM 622 ), LiNi 0.8 Co 0.1 Mn 0.1 O 2 (also referred to as NCM 811 ), and LiNi 0.8 Co 0.2 Mn 0.2 O 2 (also referred to as NCM 811 ), lithium
  • lithium-containing phosphates with an olivine structure may include, but are not limited to, one or more of lithium iron phosphate (such as LiFePO 4 (also referred to as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO 4 ), a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon.
  • lithium iron phosphate such as LiFePO 4 (also referred to as LFP)
  • LiMnPO 4 lithium manganese phosphate
  • LiMnPO 4 lithium manganese phosphate
  • LiMnPO 4 lithium manganese phosphate and carbon
  • the positive electrode film layer may also optionally include a binder.
  • the binder may include one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylate resin.
  • PVDF polyvinylidene fluoride
  • PTFE polytetrafluoroethylene
  • PTFE polytetrafluoroethylene
  • vinylidene fluoride-tetrafluoroethylene-propylene terpolymer vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer
  • the positive electrode film layer may further include a conductive agent, which may include, for example, one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.
  • a conductive agent which may include, for example, one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.
  • the positive electrode sheet can be prepared in the following manner: the components for preparing the positive electrode sheet, such as the positive electrode active material, the conductive agent, the binder and any other components are dispersed in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; the positive electrode slurry is coated on the positive electrode collector, and after drying, cold pressing and other processes, the positive electrode sheet can be obtained.
  • a solvent such as N-methylpyrrolidone
  • the negative electrode sheet includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector, wherein the negative electrode film layer includes a negative electrode active material.
  • the negative electrode current collector has two opposite surfaces in its own thickness direction, and the negative electrode film layer is disposed on any one or both of the two opposite surfaces of the negative electrode current collector.
  • the negative electrode current collector may be a metal foil or a composite current collector.
  • a metal foil a copper foil may be used.
  • the composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material substrate.
  • the composite current collector may 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 substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
  • PP polypropylene
  • PET polyethylene terephthalate
  • PBT polybutylene terephthalate
  • PS polystyrene
  • PE polyethylene
  • the negative electrode active material may adopt the negative electrode active material for the battery known in the art.
  • the negative electrode active material may include one or more of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, etc.
  • the silicon-based material may be selected from one or more of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys.
  • the tin-based material may be selected from one or more of elemental tin, tin oxide compounds, and tin alloys.
  • the present application is not limited to these materials, and other traditional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.
  • the negative electrode film layer may further include a binder.
  • the binder may be selected from one or more of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA) and carboxymethyl chitosan (CMCS).
  • the negative electrode film layer may further include a conductive agent, which may be selected from one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.
  • a conductive agent which may be selected from one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.
  • the negative electrode film layer may optionally include other additives, such as a thickener (eg, sodium carboxymethyl cellulose (CMC-Na)).
  • a thickener eg, sodium carboxymethyl cellulose (CMC-Na)
  • the negative electrode sheet can be prepared by the following method: the components for preparing the negative electrode sheet, such as the negative electrode active material, the conductive agent, the binder and any other components are dispersed in a solvent (such as deionized water) to form a negative electrode slurry; the negative electrode slurry is coated on the negative electrode collector, and after drying, cold pressing and other processes, the negative electrode sheet can be obtained.
  • a solvent such as deionized water
  • the electrolyte plays a role in conducting ions between the positive electrode and the negative electrode.
  • the present application has no specific restrictions on the type of electrolyte, which can be selected according to needs, including electrolyte salts and solvents.
  • the electrolyte salt can be selected from one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl imide), lithium bis(trifluoromethanesulfonyl imide), lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalatoborate, lithium dioxalatoborate, lithium difluorodioxalatophosphate, and lithium tetrafluorooxalatophosphate.
  • the solvent can be selected from one or more of ethylene carbonate, ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, propylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, cyclopentane sulfone, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone.
  • the electrolyte may further include additives, such as negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery properties, such as additives that improve battery overcharge performance, additives that improve battery high or low temperature performance, etc.
  • additives such as negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery properties, such as additives that improve battery overcharge performance, additives that improve battery high or low temperature performance, etc.
  • the positive electrode sheet, the negative electrode sheet, and the separator may be formed into an electrode assembly by a winding process or a lamination process.
  • the secondary battery may include an outer package, which may be used to encapsulate the electrode assembly and the electrolyte.
  • the outer packaging of the secondary battery may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc.
  • the outer packaging of the secondary battery may also be a soft package, such as a bag-type soft package.
  • the material of the soft package may be plastic, and examples of the plastic include polypropylene, polybutylene terephthalate, and polybutylene succinate.
  • the present application also provides a secondary battery, which includes a positive electrode sheet, a negative electrode sheet, and a separator disposed between the positive electrode sheet and the negative electrode sheet. Furthermore, the present application also provides an electrochemical device, which includes a positive electrode sheet, a negative electrode sheet, and a separator disposed between the positive electrode sheet and the negative electrode sheet.
  • the present application also provides an electric device using the above electrochemical device (secondary battery) as a power source, and the electric device may be, but is not limited to, a mobile phone, a tablet, a laptop, an electric toy, an electric tool, a battery car, an electric car, a ship, a spacecraft, etc.
  • the electric toy may include a fixed or mobile electric toy, for example, a game console, an electric car toy, an electric ship toy, an electric airplane toy, etc.
  • the spacecraft may include an airplane, a rocket, a space shuttle, a spacecraft, etc.
  • Inorganic boehmite particles with a Dv50 of 1 ⁇ m and polyacrylate are mixed in a mass ratio of 90:10 and dissolved in deionized water to form an inorganic coating slurry with a solid content of 50%.
  • the resulting inorganic coating slurry is then evenly coated on one side of a PE base film using a micro-concave coating method to obtain a heat-resistant layer, which is then dried in an oven.
  • An organic coating was prepared according to the parameters of the first polymer and the second polymer in each example in Table 1 below and auxiliary components (the thickener is sodium carboxymethyl cellulose, and the wetting agent is sulfonate and dimethyl silane), wherein the first polymer, the second polymer, and the auxiliary components totaled 100 parts by weight, and then deionized water was added for stirring, and the viscosity of the slurry was adjusted to 50 mPa ⁇ s and the solid content was 5%, to obtain slurry A.
  • the above slurry A was evenly coated on the surface of the inorganic coating of the PE base film to obtain a first coating, the coating weight of the first coating was 0.2 g/m 2 , and the first coating was dried in an oven.
  • auxiliary components thickener is sodium carboxymethyl cellulose, wetting agent is sulfonate and dimethyl silane
  • auxiliary components thickener is sodium carboxymethyl cellulose, wetting agent is sulfonate and dimethyl silane
  • 1-4 only adds the first polymer and auxiliary components, and the first polymer and auxiliary components are 100 parts by weight in total
  • Comparative Examples 1-1 to 1-3 add the first polymer, the second polymer and auxiliary components, and the first polymer, the second polymer, and the auxiliary components are 100 parts by weight in total.
  • the swelling degree of the second polymer added in Comparative Examples 1-3 is greater than 30%; then deionized water is added for stirring, and the viscosity of the slurry is adjusted to 50mPa ⁇ s and the solid content is 5% to obtain comparative slurry A.
  • the comparative slurry A is evenly coated on the surface of the inorganic coating of the PE base film to obtain the first coating of the comparative example, and the coating weight of the first coating of the comparative example is 0.2g/ m2 , and it is dried in an oven.
  • slurry B 90g of high molecular polymer binder was added into a stirrer, and then 0.5g of sodium carboxymethyl cellulose was added, and the mixture was stirred and mixed evenly; 8.5g of dimethylsiloxane as a wetting agent was added, and then deionized water was added and stirred, and the viscosity of the slurry was adjusted to 40mPa ⁇ s, and the solid content was 5%, to obtain slurry B.
  • the slurry B was evenly coated on the other surface of the PE base film to obtain a second coating layer, and the coating weight of the second coating layer was 0.5g/ m2 , and the mixture was dried in an oven.
  • the positive electrode active materials lithium cobalt oxide, acetylene black, and polyvinylidene fluoride (PVDF) are mixed in a mass ratio of 94:3:3, and then N-methylpyrrolidone (NMP) is added as a solvent to prepare a slurry with a solid content of 75%, and stirred evenly.
  • NMP N-methylpyrrolidone
  • the slurry is evenly coated on one surface of an aluminum foil with a thickness of 12 ⁇ m, dried at 90°C, and cold pressed to obtain a positive electrode sheet with a positive electrode active material layer thickness of 100 ⁇ m, and then the above steps are repeated on the other surface of the positive electrode sheet to obtain a positive electrode sheet coated with a positive electrode active material layer on both sides.
  • the positive electrode sheet is cut into a specification of 74mm ⁇ 867mm and welded to the pole ear for standby use.
  • the negative electrode active material artificial graphite, acetylene black, styrene-butadiene rubber and sodium carboxymethyl cellulose are mixed in a mass ratio of 96:1:1.5:1.5, and then deionized water is added as a solvent to prepare a slurry with a solid content of 70% (mass content), and stirred evenly.
  • the slurry is evenly coated on one surface of a copper foil with a thickness of 8 ⁇ m, dried at 110°C, and cold pressed to obtain a negative electrode sheet with a single-sided negative electrode active material layer coated with a negative electrode active material layer with a thickness of 150 ⁇ m, and then the above coating steps are repeated on the other surface of the negative electrode sheet to obtain a negative electrode sheet with a double-sided negative electrode active material layer coated.
  • the negative electrode sheet is cut into a specification of 74 mm ⁇ 867 mm and welded to the pole ear for standby use.
  • non-aqueous organic solvents of ethylene carbonate (EC), diethyl carbonate (DEC), propylene carbonate (PC), and propyl propionate (PP) are mixed in a mass ratio of 2:3:2:3, and then lithium hexafluorophosphate ( LiPF6 ) is added to the non-aqueous organic solvent to dissolve and mix evenly to obtain an electrolyte, wherein the ratio of LiPF6 to EC, DEC, PC, and PP is 8.7:20:30:20:30.
  • the positive electrode sheet, separator, and negative electrode sheet prepared above are stacked in order, the side of the separator with the first coating is in contact with the positive electrode sheet, and the side of the separator with the second coating is in contact with the negative electrode sheet, and they are wound to obtain an electrode assembly.
  • the electrode assembly is packed into an aluminum-plastic film packaging bag, and the moisture is removed at 80°C, and the prepared electrolyte is injected, and a lithium-ion battery is obtained through vacuum packaging, standing, forming, shaping, and other processes.
  • the national standard GB/T 2790-1995 that is, the 180° peel test standard is adopted to test the adhesion between the separator and the positive electrode sheet or the negative electrode sheet.
  • the separator and the positive electrode sheet are cut into 54.2mm ⁇ 72.5mm samples, the separator and the positive electrode sheet are compounded, and hot pressing is performed using a hot press.
  • the hot pressing conditions are: temperature 85°C, pressure 1Mpa, hot pressing time 85s (seconds).
  • the compounded samples are cut into 15mm ⁇ 54.2mm strips, and the adhesion between the separator and the positive electrode sheet at room temperature (25°C) is tested according to the 180° peel test standard.
  • test temperature is 25°C;
  • Test process Let stand for 30 minutes at a test temperature of 25°C, then charge at a constant current of 12.4A to 4.22V, and charge at a constant voltage of 1.8C; then charge at a constant current of 1.8C to 4.3V, and charge at a constant voltage of 1.5C; charge at a constant current of 1.5C to 4.48V, and charge at a constant voltage of 1.2C; charge at a constant current of 1.2C to 4.53V, and charge at a constant voltage of 0.26C; let stand for 5 minutes, discharge to 3.2V at a current density of 0.7C; let stand for 5 minutes, and cycle 800 times from step 3 to step 9.
  • the high temperature cycle test was performed as above, except that the temperature condition was set to 45°C.
  • Preparation of film disassemble the battery cell, take out the diaphragm, and dissolve it in the organic solvent NMP with a solvent-solution ratio of 1:9. Place the beaker containing the above suspension on a disperser and stir it for 1.5 hours. Let the stirred solution stand for 30 minutes to eliminate bubbles. Use a filter to filter to remove insoluble impurities and base film. Pour this solution into the film preparation mold, and remove any bubbles in advance. Put the mold in an oven, set the temperature to 60°C, and the time to 12 hours.
  • the hot box test pass rates of the batteries of Examples 1-1 to 1-21 can reach 80% or more and are significantly higher than the hot box test pass rates of the batteries of Comparative Examples 1-2 to 1-4.
  • the capacity retention rates of the batteries of Examples 1-1 to 1-21 in the room temperature cycle test at 25°C 4C for 800 cycles can reach 80% and above. It can be seen that by using the organic coating containing the first polymer with a low melting point and the second polymer with a low swelling degree in the present application, the hot box test pass rate of the battery can be effectively improved on the basis of ensuring the room temperature cycle performance of the battery.
  • the second group of examples is to prepare an organic coating according to the parameters of the first polymer and the second polymer in Table 2 below and add auxiliary components (thickener is sodium carboxymethyl cellulose, wetting agent is sulfonate and dimethyl silane) in a proportion, wherein the first polymer is 65 parts by weight, the second polymer is 30 parts by weight, and the auxiliary components are 5 parts by weight, and then deionized water is added for stirring, and the viscosity of the slurry is adjusted to 50mPa ⁇ s, and the solid content is 5%, to obtain slurry A.
  • auxiliary components thickenethacrylate, sulfonate and dimethyl silane
  • the above slurry A is evenly coated on the surface of the inorganic coating of the PE base film to obtain a first coating, the coating weight of the first coating is 0.2g/ m2 , and it is dried in an oven.
  • the proportion of cyclic carboxylic acid esters (such as EC) in the electrolyte is correspondingly increased to meet the regulation of the following linear carboxylic acid ester content.
  • the third group of examples is to prepare an organic coating according to the parameters of the first polymer and the second polymer in Table 3 below and add auxiliary components (the thickener is sodium carboxymethyl cellulose, and the wetting agent is sulfonate and dimethyl silane) in a proportion, wherein the first polymer is 65 parts by weight, the second polymer is 30 parts by weight, and the auxiliary components are 5 parts by weight, and then deionized water is added.
  • Stirring was performed to adjust the viscosity of the slurry to 50 mPa ⁇ s and the solid content to 5% to obtain slurry A.
  • the slurry A was evenly coated on the inorganic coating surface of the PE base film to obtain a first coating with a coating weight of 0.2 g/m 2 , and dried in an oven.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Cell Separators (AREA)
  • Secondary Cells (AREA)

Abstract

一种隔离膜，包括基膜和设置在基膜的一表面上的有机涂层。有机涂层含有第一聚合物和第二聚合物。第一聚合物的熔点T满足60℃≤T≤100℃，第二聚合物在溶液中于60℃放置24h的溶胀度D≤30％。第一聚合物维持电池充放电循环过程中的粘结力需求，电池充放电发热时，第一聚合物较易软化，粘结力下降，使得隔离膜与电池极片之间的界面打开，有助于降低热量积累，提升电芯热箱安全性能；第二聚合物溶胀度较低，能够在电芯中维持原有形貌，有效改善低熔点的第一聚合物在电芯热压过程中熔融成膜问题，改善电芯的循环性能。还提供二次电池、电化学装置和用电装置。

Description

隔离膜、二次电池、电化学装置和用电装置 技术领域
本申请涉及一种隔离膜、含有该隔离膜的二次电池和电化学装置以及含有该二次电池或电化学装置的用电装置。
背景技术
电芯充电倍率的快速提升以及电芯能量密度的增加，不利于电芯的热箱窗口(电芯充电后放入热箱中测试，电芯能够不起火、不爆炸且不冒烟的安全温度)的提升。为提高电池电芯的热箱窗口，提升电芯的安全性能，通常可采用两种方式：调整电解液的溶剂体系；或者使用低粘结性能的聚偏氟乙烯涂层涂覆在隔离膜上。然而，电解液体系调整，会恶化电芯的循环性能，同时电芯的低温性能有变差风险；而使用过低粘结力的聚偏氟乙烯涂层，易带来电池电芯的变形，会恶化电芯的高温存储性能。
发明内容
鉴于此，本申请第一方面提供一种隔离膜，包括：
基膜；
有机涂层，设置在所述基膜的一表面上，所述有机涂层含有第一聚合物和第二聚合物；
所述第一聚合物的熔点T满足60℃≤T≤100℃；
所述第二聚合物在电解液中于60℃放置24h的溶胀度D≤30％，所述电解液的六氟磷酸锂、碳酸乙烯酯、碳酸二乙酯、碳酸亚丙酯、丙酸丙酯的质量比为8.7：20：30：20：30。
第一方面提供的隔离膜中，所述第一聚合物可维持电池充放电循环过程中的粘结力需求，另外可以改善高温存储性能；电池充放电发热时，低熔点的第一聚合物较容易发生软化，粘结力显著下降，使得隔离膜与电池极片(正极极片)二者之间的界面打开，有助于降低热量积累，提升电芯热箱安全性能；所述第二聚合物溶胀度D较低，能够在电芯中维持原有形貌，不会堵塞基膜的孔隙，能够有效改善低熔点的第一聚合物在电芯热压过程中熔融成膜问题，改善电芯的循环性能。
结合第一方面，在一些实施例中，在所述有机涂层中，所述第一聚合物的重量百分含量大于等于40％且小于等于95％，所述第二聚合物的重量百分含量小于等于50％。
可以看出，本申请通过合理配制第一聚合物与第二聚合物的二者的比例，在保证电芯性能的基础上提升电芯的热箱测试窗口。所述第一聚合物的含量越高，高温失效效果越好，但含量太高，隔离膜容易堵孔，造成电芯的动力学下降，循环性能变差；所述第二聚合物的含量越高，电芯的循环性能越好，但含量太高，隔离膜在常温下的粘结力过低，容易导致高温储存性能变差，电池电芯有变形风险，会导致循环性能的降低。
结合第一方面，在一些实施例中，在所述有机涂层中，所述第一聚合物的重量百分含量大于等于60％且小于等于95％，所述第二聚合物的重量百分含量小于等于30％。
结合第一方面，在一些实施例中，当将所述隔离膜应用于电化学电池电芯中，所述第二聚合物的溶胀度D和电解液中线性羧酸酯的含量H，满足D＝K*H+0.1，其中0.01≤K≤0.08。
结合第一方面，在一些实施例中，10％≤H≤50％。
可以看出，通过调整第一聚合物与第二聚合物的配比以及电解液的线性羧酸酯含量，可以在保证电芯性能的基础上提升热箱测试通过率。
结合第一方面，在一些实施例中，所述第一聚合物的中值粒径Dv50满足1.0μm≤Dv50≤2μm。
可以看出，当第一聚合物粒径过大，会使所述有机涂层的粘结性变差而厚度增大，致使电芯的体积能量密度较低；第一聚合物粒径过小，会造成隔离膜堵孔，导致电池的循环性能变差。本申请中，通过设定第一聚合物合适的粒径范围，可保证所述有机涂层的粘结性以及适宜的厚度。
结合第一方面，在一些实施例中，所述第一聚合物的熔点T满足60℃≤T≤85℃。
结合第一方面，在一些实施例中，所述第二聚合物呈球形或类球形，所述第二聚合物的球形度R满足0.7≤R＜1。
结合第一方面，在一些实施例中，所述第二聚合物呈球形或类球形，所述第二聚合物的球形度R满足0.8≤R＜1。
可以看出，第二聚合物的球形度高，能够使第二聚合物用量较少而达到较好的效果，球形或类球形的第二聚合物在所述有机涂层中堆积密度较低，能够增加有机涂层的孔隙率，提升电芯的循环性能。
结合第一方面，在一些实施例中，所述第二聚合物在电解液中于85℃放置24h的溶胀度D满足10％≤D≤50％。
可以看出，本申请通过选取低溶胀度的第二聚合物，当所述隔离膜应用于电芯中时，即使温度升高，第二聚合物也能够较好地保持原有形貌，且所述第二聚合物相对所述第一聚合物具有较高的熔点，例如熔点高于130℃，能够在电芯中维持原有形貌，不会堵塞基膜的孔隙，能够有效改善低熔点的第一聚合物在电芯热压过程中熔融成膜问题，改善电芯的循环性能。通过选取不同物质种类、分子量或不同交联度实现不同溶胀度物质的选择。
结合第一方面，在一些实施例中，所述第一聚合物包括接枝共聚物，所述接枝共聚物中的聚合物主体的单体包括乙烯、丙烯、偏氟乙烯、丙烯酸、丙烯酸酯、苯乙烯、丙烯腈、马来酸酐、氯乙烯和氯丙烯中的至少一种，用于接枝的单体包括马来酸酐、丙烯酸酯和丙烯酸中的至少一种；所述接枝共聚物在所述第一聚合物中的重量百分含量为大于等于3％且小于等于10％。
结合第一方面，在一些实施例中，所述第二聚合物包括偏氟乙烯、六氟丙烯、丙烯、氯乙烯、苯乙烯、丁二烯、丙烯酸酯、丙烯酸中的至少一种单体的聚合物，所述第二聚合物为均聚物、共聚物和共混聚合物中的至少一种。
第二方面，本申请提供一种二次电池，其包括正极极片、负极极片以及设置在所述正极极片和所述负极极片之间的上述的隔离膜，其中所述有机涂层位于所述正极极片和所述基膜之间。
第三方面，本申请提供一种电化学装置，其包括正极极片、负极极片以及设置在所述正极极片和所述负极极片之间的上述的隔离膜，其中所述有机涂层位于所述正极极片和所述基膜之间。
第四方面，本申请提供一种用电装置，上述的二次电池或上述的电化学装置。
附图说明
图1为本申请一实施方式的隔离膜的结构示意图。
图2为本申请一实施方式的隔离膜的作用机理示意图。
主要元件符号说明：
隔离膜                              10
基膜                                11
有机涂层                            13
无机涂层                            15
其他有机涂层                        17
正极极片                            20
负极极片                            30
具体实施方式
下面结合本申请实施例中的附图对本申请实施例进行描述。
隔离膜是电池中非常关键的部分，是设置在电池正极和负极之间的一层隔膜材料，对电池的安全性能和成本有直接影响。隔离膜的主要作用是隔离正极和负极，并使电池内的电子不能自由穿过，而让电解液中的离子自由通过。
本申请提供一种二次电池的隔离膜，能够有效提高电池电芯的热箱窗口，提升电芯的安全性能。请参阅图1，隔离膜10包括基膜11和设置在所述基膜11的一表面上的有机涂层13。请参阅图2，使用时，隔离膜10具有有机涂层13的一侧朝向正极极片20。有机涂层13含有第一聚合物和第二聚合物。
本申请对于基膜11的种类没有特别的限制，只要能实现本申请的目的即可。所述基膜11可为由对电解液稳定的材料所形成的树脂、玻璃纤维、无机物等。一些实施例中，所述基膜11包括保液性优异的多孔性片材或无纺布状形态的物质等。树脂或玻璃纤维隔离膜基膜的材料的实例可包括，但不限于聚烯烃、芳香族聚酰胺、聚四氟乙烯、聚醚砜等。以聚烯烃为例，所述基膜11的材料可选自聚丙烯和聚乙烯中的一种或多种。
本申请对于基膜11的厚度不做限定，只要能够实现本申请的目的即可，例如基膜11的厚度可以为5～50μm，优选为5～30μm。
本申请中，所述第一聚合物的熔点T较低，60℃≤T≤100℃。进一步的，一些实施例中，所述第一聚合物的熔点T满足60℃≤T≤85℃。
所述第一聚合物提供有机涂层13的粘度，在低于熔点的温度(例如常温)下所述第一聚合物具备高粘结性能，可维持电池充放电循环过程中的粘结力需求，另外可以改善电池的高温存储性能。本申请通过选取低熔点的第一聚合物，以便电池充放电发热时，例如当温度升高达到熔点T及以上时，低熔点的所述第一聚合物较容易发生软化产生流动性，粘结力显著下降，使得隔离膜与正极极片二者之间的界面打开，有助于降低热量积累，提升电芯热箱安全性能。
当第一聚合物粒径过大，会使所述有机涂层13的粘结性变差而厚度增大，致使电芯的体积能量密度较低；第一聚合物粒径过小，会造成隔离膜堵孔，导致电池的循环性能变差。本申请中，所述第一聚合物的中值粒径Dv50满足0.8μm＜Dv50＜2μm。一些实施 例中，所述第一聚合物的中值粒径Dv50满足1.0μm≤Dv50≤2μm。通过设定第一聚合物在合适的粒径范围内，可保证所述有机涂层13的粘结性以及具有适宜的厚度。
当所述隔离膜10应用于电池中时，电解液会渗入多孔结构的隔离膜10中，而所述有机涂层也相当于处于被电解液浸泡的状态。第二聚合物在电解液中于60℃放置24h的溶胀度D≤30％，所述电解液的六氟磷酸锂、碳酸乙烯酯、碳酸二乙酯、碳酸亚丙酯、丙酸丙酯的质量比为8.7：20：30：20：30。
进一步的，一些实施例中，第二聚合物在电解液中于85℃放置24h的溶胀度10％≤D≤50％。本申请中，溶胀度的定义：聚合物分子吸附溶剂分子达到溶胀平衡时，溶胀后的体积与未溶胀前的体积的比值减去1。通常，聚合物的溶胀度与聚合物材料成分、分子量、分子链的长短和分子链的交联程度等相关。本申请可通过选取适当的材料成分、大的分子量、长的分子链或分子链交联程度大等，保证第二聚合物的溶胀度。
本申请通过选取高强度、低溶胀度的第二聚合物，当所述隔离膜10应用于电芯中时，第二聚合物也能够保持原有形貌。此外，第二聚合物相对第一聚合物具有较高的熔点，例如熔点高于130℃，能够在电芯中维持原有形貌，不会堵塞基膜11的孔隙，能够有效改善低熔点的第一聚合物在电芯热压过程中熔融成膜问题，改善电池电芯的循环性能。
第二聚合物在隔离膜10中呈球形或类球形，所述第二聚合物的球形度R满足0.7≤R≤1.0。进一步的，一些实施例中，第二聚合物的球形度R满足0.8≤R≤1.0。第二聚合物的球形度高，能够使第二聚合物在所述有机涂层13中的用量较少而达到较好的效果，且球形或类球形的第二聚合物在所述有机涂层13中堆积密度较低，能够增加有机涂层的孔隙率，提升电芯的循环性能。
随着电池温度的升高，第一聚合物较易软化失去粘结性，而第二聚合物由于熔点相对较高，不会发生软化，而保持其刚性颗粒状。
所述第一聚合物的含量越高，高温失效效果越好，但含量太高，隔离膜10容易堵孔，造成电芯的动力学下降，循环性能变差。
所述第二聚合物的含量越高，电芯的循环性能越好，但含量太高，隔离膜在常温下的粘结力越差，容易导致高温储存性能变差，循环有变形风险。
因此，需要合理配制第一聚合物与第二聚合物的二者的比例，才可以在保证电芯性能的基础上提升电芯的热箱测试窗口。本申请中，在所述有机涂层13中，所述第一聚合物的重量百分含量大于等于40％且小于等于95％，所述第二聚合物的重量百分含量小于等于50％。进一步的，一些实施例中，在所述有机涂层13中，所述第一聚合物的重量百分含量大于等于60％且小于等于95％，所述第二聚合物的重量百分含量小于等于30％。
本申请中，所述有机涂层13中，所述第二聚合物的重量百分含量的大于等于10％。
另外，电解液中线性羧酸酯的含量越高，电芯性能越好，但含量太高，会导致聚合物溶胀过大，堵塞隔离膜孔隙，导致电芯性能变差。当将所述隔离膜应用于电池电芯中，电解液中线性羧酸酯的重量百分含量为H，其中10％≤H≤50％。
本申请中，第二聚合物的溶胀度D和电解液中线性羧酸酯的含量H，满足D＝K*H+0.1，其中0.01≤K≤0.08。
如此，通过调整第一聚合物与第二聚合物的配比以及电解液的线性羧酸酯含量，可以在保证电芯性能的基础上提升热箱测试上限窗口。
第一聚合物的Dv10满足0.1μm≤Dv10≤0.7μm，Dv90满足2μm≤Dv90≤5μm。
第二聚合物的Dv10满足0.1μm≤Dv10≤0.5μm，Dv50满足0.5μm≤Dv50≤2μm，Dv90满足2μm≤Dv90≤5μm。第二聚合物的Dv90与所述第一聚合的Dv90的比值S满足0.6≤S≤1.0。
一些实施例中，第一聚合物包括乙烯、丙烯、偏氟乙烯、丙烯酸、丙烯酸酯、苯乙烯、丙烯腈、马来酸酐、氯乙烯和氯丙烯中的至少一种单体的聚合物。第一聚合物为均聚物、共聚物和共混聚合物中的至少一种。
一些实施例中，所述第一聚合物包括接枝共聚物，所述接枝共聚物中的聚合物主体的单体包括乙烯、丙烯、偏氟乙烯、丙烯酸、丙烯酸酯、苯乙烯、丙烯腈、马来酸酐、氯乙烯和氯丙烯中的至少一种，用于接枝的单体包括马来酸酐、丙烯酸酯和丙烯酸中的至少一种。
一些实施例中，当第一聚合物含有接枝共聚物时，接枝共聚物在第一聚合物中的重量百分含量为大于等于3％且小于等于10％。
一些实施例中，第二聚合物包括偏氟乙烯、六氟丙烯、丙烯、氯乙烯、苯乙烯、丁二烯、丙烯酸酯、丙烯酸中的至少一种单体的聚合物，第二聚合物为均聚物、共聚物和共混聚合物中的至少一种。
一些实施例中，第一聚合物的平均分子量为大于等于30万且小于等于100万。第二聚合物的平均分子量为大于等于80万且小于等于200万。
可以理解的，可选的，有机涂层除了含有上述的第一聚合物和第二聚合物，还含有辅助组分，辅助组分在有机涂层中的重量百分含量不超过10％。所述辅助组分可包括常规的增稠剂和润湿剂等。增稠剂可为羧甲基纤维素钠或羧甲基纤维素锂，在所述有机涂层中的重量百分含量可为0.5％～1.5％。润湿剂包括磺酸盐和二甲基硅烷，在所述有机涂层中的重量百分含量可为1％～10％。
一些实施例中，所述有机涂层在基膜上的涂布重量为大于等于0.5mg/5000mm2且小于等于3mg/5000mm2。所述有机涂层的涂布厚度大于等于0.5μm且小于等于5μm。进一步的，一些实施例中，所述有机涂层在所述基膜上的涂布重量大于等于0.5mg/5000mm2且小于等于1.5mg/5000mm2。
可选的，一些实施例中，如图1所示，隔离膜10还包括设置在基膜11和有机涂层13之间的无机涂层15。无机涂层15用以提升隔离膜10的耐热性和机械强度。所述无机涂层15包括陶瓷，陶瓷包括氧化铝、勃姆石、二氧化钛、二氧化硅、二氧化锆、二氧化锡、氢氧化镁、氧化镁、氧化锌、硫酸钡、氮化硼或氮化铝中的至少一种。
可以理解的，如图1和图2所示，隔离膜10还包括设置在基膜11的另一表面的其他有机涂层17。其他有机涂层17与上述有机涂层13分别设置于基膜11的相对的表面上，即其他有机涂层17设置在基膜11朝向负极极片30的表面。本申请对于其他有机涂层17种类没有特别的限制，只要能起到粘接隔离膜和负极的作用即可。一些实施例中，其他有机涂层17主要含有粘结剂和增稠剂。
请参阅图2，本申请还提供一种电化学装置，包括正极极片20、负极极片30、电解液以及设置在所述正极极片20和所述负极极片30之间的上述隔离膜10。其中所述有机涂层13设置在所述基膜11朝向所述正极极片20的表面，即位于所述正极极片20和所述基膜11之间可用以粘接正极极片20与隔离膜10的作用。所述电化学装置可为二次电池。电解液渗入该隔离膜10中。图2作为示意，隔离膜10并未呈现粘接正极极片20和 负极极片30的状态。电化学装置的正极极片、负极极片、电解液均可采用本领域公知的种类。
[正极极片]
正极极片包括正极集流体以及设置在正极集流体至少一个表面的正极膜层。作为示例，正极集流体沿其自身厚度方向具有相对的两个表面，正极膜层设置在正极集流体相对的两个表面的其中任意一者或两者上。所述正极膜层包括正极活性材料。
在一些实施方式中，所述正极集流体可采用金属箔片或复合集流体。例如，作为金属箔片，可采用铝箔。复合集流体可包括高分子材料基层和形成于高分子材料基层至少一个表面上的金属层。复合集流体可通过将金属材料(铝、铝合金、镍、镍合金、钛、钛合金、银及银合金等)形成在高分子材料基材(如聚丙烯(PP)、聚对苯二甲酸乙二醇酯(PET)、聚对苯二甲酸丁二醇酯(PBT)、聚苯乙烯(PS)、聚乙烯(PE)等的基材)上而形成。
在一些实施方式中，正极活性材料可采用本领域公知的用于电池的正极活性材料。作为示例，正极活性材料可包括以下材料中的一种或多种：橄榄石结构的含锂磷酸盐、锂过渡金属氧化物及其各自的改性化合物。但本申请并不限定于这些材料，还可以使用其他可被用作电池正极活性材料的传统材料。这些正极活性材料可以仅单独使用一种，也可以将两种以上组合使用。其中，锂过渡金属氧化物的示例可包括但不限于锂钴氧化物(如LiCoO2)、锂镍氧化物(如LiNiO2)、锂锰氧化物(如LiMnO2、LiMn2O4)、锂镍钴氧化物、锂锰钴氧化物、锂镍锰氧化物、锂镍钴锰氧化物(如LiNi1/3Co1/3Mn1/3O2(也可以简称为NCM333)、LiNi0.5Co0.2Mn0.3O2(也可以简称为NCM523)、LiNi0.5Co0.25Mn0.25O2(也可以简称为NCM211)、LiNi0.6Co0.2Mn0.2O2(也可以简称为NCM622)、LiNi0.8Co0.1Mn0.1O2(也可以简称为NCM811)、锂镍钴铝氧化物(如LiNi0.85Co0.15Al0.05O2)及其改性化合物等中的一种或多种。橄榄石结构的含锂磷酸盐的示例可包括但不限于磷酸铁锂(如LiFePO4(也可以简称为LFP))、磷酸铁锂与碳的复合材料、磷酸锰锂(如LiMnPO4)、磷酸锰锂与碳的复合材料、磷酸锰铁锂、磷酸锰铁锂与碳的复合材料中的一种或多种。
在一些实施方式中，正极膜层还可选地包括粘结剂。作为示例，所述粘结剂可以包括聚偏氟乙烯(PVDF)、聚四氟乙烯(PTFE)、偏氟乙烯-四氟乙烯-丙烯三元共聚物、偏氟乙烯-六氟丙烯-四氟乙烯三元共聚物、四氟乙烯-六氟丙烯共聚物及含氟丙烯酸酯树脂中的一种或多种。
在一些实施方式中，正极膜层还可选地包括导电剂。作为示例，所述导电剂可以包括超导碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯及碳纳米纤维中的一种或多种。
在一些实施方式中，可以通过以下方式制备正极极片：将上述用于制备正极极片的组分，例如正极活性材料、导电剂、粘结剂和任意其他的组分分散于溶剂(例如N-甲基吡咯烷酮)中，形成正极浆料；将正极浆料涂覆在正极集流体上，经烘干、冷压等工序后，即可得到正极极片。
[负极极片]
负极极片包括负极集流体以及设置在负极集流体至少一个表面上的负极膜层，所述负极膜层包括负极活性材料。
作为示例，负极集流体在其自身厚度方向具有相对的两个表面，负极膜层设置在负极集流体相对的两个表面中的任意一者或两者上。
一些实施方式中，所述负极集流体可采用金属箔片或复合集流体。例如，作为金属箔片，可以采用铜箔。复合集流体可包括高分子材料基层和形成于高分子材料基材至少一个表面上的金属层。复合集流体可通过将金属材料(铜、铜合金、镍、镍合金、钛、钛合金、银及银合金等)形成在高分子材料基材(如聚丙烯(PP)、聚对苯二甲酸乙二醇酯(PET)、聚对苯二甲酸丁二醇酯(PBT)、聚苯乙烯(PS)、聚乙烯(PE)等的基材)上而形成。
一些实施方式中，负极活性材料可采用本领域公知的用于电池的负极活性材料。作为示例，负极活性材料可包括以下材料中的一种或多种：人造石墨、天然石墨、软炭、硬炭、硅基材料、锡基材料和钛酸锂等。所述硅基材料可选自单质硅、硅氧化合物、硅碳复合物、硅氮复合物以及硅合金中的一种或多种。所述锡基材料可选自单质锡、锡氧化合物以及锡合金中的一种或多种。但本申请并不限定于这些材料，还可以使用其他可被用作电池负极活性材料的传统材料。这些负极活性材料可以仅单独使用一种，也可以将两种以上组合使用。
一些实施方式中，负极膜层还可选地包括粘结剂。所述粘结剂可选自丁苯橡胶(SBR)、聚丙烯酸(PAA)、聚丙烯酸钠(PAAS)、聚丙烯酰胺(PAM)、聚乙烯醇(PVA)、海藻酸钠(SA)、聚甲基丙烯酸(PMAA)及羧甲基壳聚糖(CMCS)中的一种或多种。
一些实施方式中，负极膜层还可选地包括导电剂。导电剂可选自超导碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯及碳纳米纤维中的一种或多种。
在一些实施方式中，负极膜层还可选地包括其他助剂，例如增稠剂(如羧甲基纤维素钠(CMC-Na))等。
一些实施方式中，可以通过以下方式制备负极极片：将上述用于制备负极极片的组分，例如负极活性材料、导电剂、粘结剂和任意其他组分分散于溶剂(例如去离子水)中，形成负极浆料；将负极浆料涂覆在负极集流体上，经烘干、冷压等工序后，即可得到负极极片。
[电解液]
电解液在正极极片和负极极片之间起到传导离子的作用。本申请对电解液的种类没有具体的限制，可根据需求进行选择，包括电解质盐和溶剂。
一些实施方式中，电解质盐可选自六氟磷酸锂、四氟硼酸锂、高氯酸锂、六氟砷酸锂、双氟磺酰亚胺锂、双三氟甲磺酰亚胺锂、三氟甲磺酸锂、二氟磷酸锂、二氟草酸硼酸锂、二草酸硼酸锂、二氟二草酸磷酸锂及四氟草酸磷酸锂中的一种或多种。
在一些实施方式中，溶剂可选自碳酸乙烯酯、碳酸亚乙酯、碳酸亚丙酯、碳酸甲乙酯、碳酸二乙酯、碳酸二甲酯、碳酸二丙酯、碳酸甲丙酯、碳酸乙丙酯、碳酸亚丁酯、碳酸亚丙酯、氟代碳酸亚乙酯、甲酸甲酯、乙酸甲酯、乙酸乙酯、乙酸丙酯、丙酸甲酯、丙酸乙酯、丙酸丙酯、丁酸甲酯、丁酸乙酯、1,4-丁内酯、环丁砜、二甲砜、甲乙砜及二乙砜中的一种或多种。
在一些实施方式中，所述电解液还可选地包括添加剂。例如添加剂可以包括负极成膜添加剂、正极成膜添加剂，还可以包括能够改善电池某些性能的添加剂，例如改善电池过充性能的添加剂、改善电池高温或低温性能的添加剂等。
一些实施方式中，正极极片、负极极片和隔离膜可通过卷绕工艺或叠片工艺制成电极组件。
在一些实施方式中，二次电池可包括外包装。该外包装可用于封装上述电极组件及电解质。
在一些实施方式中，二次电池的外包装可以是硬壳，例如硬塑料壳、铝壳、钢壳等。二次电池的外包装也可以是软包，例如袋式软包。软包的材质可以是塑料，作为塑料，可列举出聚丙烯、聚对苯二甲酸丁二醇酯以及聚丁二酸丁二醇酯等。
本申请还提供一种二次电池，其包括正极极片、负极极片以及设置在所述正极极片和所述负极极片之间的隔离膜，进一步的，本申请还提供一种电化学装置，其包括正极极片、负极极片以及设置在所述正极极片和所述负极极片之间的隔离膜。
本申请还提供一种使用上述电化学装置(二次电池)作为电源的用电装置，用电装置可以为但不限于手机、平板、笔记本电脑、电动玩具、电动工具、电瓶车、电动汽车、轮船、航天器等等。其中，电动玩具可以包括固定式或移动式的电动玩具，例如，游戏机、电动汽车玩具、电动轮船玩具和电动飞机玩具等等，航天器可以包括飞机、火箭、航天飞机和宇宙飞船等。
下面通过具体实施例对本申请实施例技术方案进行进一步的说明。
无机涂层制备
将Dv50为1μm的无机粒子勃姆石与聚丙烯酸酯依照质量比90∶10混合并将其溶入到去离子水中以形成固含量为50％的无机涂层浆料，随后采用微凹涂布法将所得无机涂层浆料均匀涂布到PE基膜的其中一面上，得到耐热层，在烘箱中完成干燥。
第一组实施例有机涂层制备
第一组实施例按照下面表一各个实施例第一聚合物、第二聚合物的参数并添加辅助组分(增稠剂为羧甲基纤维素钠，润湿剂为磺酸盐和二甲基硅烷)制备有机涂层，其中第一聚合物、第二聚合物、辅助组分合计100重量份，然后加入去离子水进行搅拌，调整浆料的粘度为50mPa·s，固含量5％，得到浆料A。将上述浆料A均匀地涂布在PE基膜的无机涂层表面上，得到第一涂层，第一涂层的涂布重量0.2g/m2，在烘箱中完成干燥。
对比例隔膜涂层制备
按照下面表一各个对比例的参数并添加辅助组分(增稠剂为羧甲基纤维素钠，润湿剂为磺酸盐和二甲基硅烷)配比制备对比例有机涂层，1-4只添加第一聚合物和辅助组分，第一聚合物和辅助组分合计100重量份；对比例1-1至对比例1-3添加第一聚合物、第二聚合物和辅助组分，第一聚合物、第二聚合物、辅助组分合计100重量份，对比例1-3添加的第二聚合物的溶胀度大于30％；然后加入去离子水进行搅拌，调整浆料的粘度为50mPa·s，固含量5％，得到对比例浆料A。将上述对比例浆料A均匀地涂布在PE基膜的无机涂层表面上，得到对比例的第一涂层，对比例的第一涂层的涂布重量0.2g/m2，在烘箱中完成干燥。
高粘结涂层制备
将90g高分子聚合物粘结剂加入搅拌器中，再加入0.5g羧甲基纤维素钠，搅拌混合均匀；加入8.5g润湿剂二甲基硅氧烷，然后加入去离子水进行搅拌，调整浆料的粘度为40mPa·s，固含量5％，得到浆料B。将上述浆料B均匀地涂布在PE基膜的另一个表面上，得到第二涂层，第二涂层的涂布重量0.5g/m2，在烘箱中完成干燥。
正极极片的制备
将正极活性材料钴酸锂、乙炔黑、聚偏二氟乙烯(PVDF)按质量比94∶3∶3混合，然后加入N-甲基吡咯烷酮(NMP)作为溶剂，调配成固含量为75％的浆料，并搅拌均匀。将浆料均匀涂布在厚度为12μm的铝箔的一个表面上，90℃条件下烘干，冷压后得到正极活性材料层厚度为100μm的正极极片，然后在该正极极片的另一个表面上重复以上步骤，得到双面涂布有正极活性材料层的正极极片。将正极极片裁切成74mm×867mm的规格并焊接极耳后待用。
负极极片的制备
将负极活性材料人造石墨、乙炔黑、丁苯橡胶及羧甲基纤维素钠按质量比96∶1∶1.5∶1.5混合，然后加入去离子水作为溶剂，调配成固含量为70％(质量含量)的浆料，并搅拌均匀。将浆料均匀涂布在厚度为8μm的铜箔的一个表面上，110℃条件下烘干，冷压后得到负极活性材料层厚度为150μm的单面涂布负极活性材料层的负极极片，然后在该负极极片的另一个表面上重复以上涂布步骤，得到双面涂布有负极活性材料层的负极极片。将负极极片裁切成74mm×867mm的规格并焊接极耳后待用。
电解液的制备
在含水量小于10ppm的环境下，将非水有机溶剂碳酸乙烯酯(EC)、碳酸二乙酯(DEC)、碳酸亚丙酯(PC)、丙酸丙酯(PP)按照质量比2∶3∶2∶3混合，然后向非水有机溶剂中加入六氟磷酸锂(LiPF6)溶解并混合均匀，得到电解液，其中，LiPF6与EC、DEC、PC、PP的比值为8.7：20：30：20：30。
锂离子电池的制备
将上述制备的正极极片、隔离膜、负极极片按顺序叠好，将隔离膜具有第一涂层的一面与正极极片接触，将隔离膜具有第二涂层的一面与负极极片接触，并卷绕得到电极组件。将电极组件装入铝塑膜包装袋中，并在80℃下脱去水分，注入配好的电解液，经过真空封装、静置、化成、整形等工序得到锂离子电池。
隔离膜与电极极片间粘结力测试
采用国家标准GB/T 2790-1995，即采用180°剥离测试标准测试隔离膜与正极极片或负极极片之间的粘结力，将隔离膜和正极极片裁切成54.2mm×72.5mm样品，将隔离膜与正极极片复合，使用热压机热压，热压条件为：温度85℃，压力1Mpa，热压时间85s(秒)，将复合好的样品裁切成15mm×54.2mm小条，按照180°剥离测试标准测试常温下(25℃)隔离膜与正极极片之间的粘结力。
热箱窗口测试
一、预处理电芯满充流程
1)测试温度为25℃；
2)休眠30min；
3)0.2C倍率恒流充电到4.5V，4.5V恒压充电到截至电流0.025C。
二、测试过程：
①测试前后检查外观并拍照；
②感温线贴线位置；
③将样品竖直放置于箱体中按照6℃升温速度升温至130℃并保持60min；
④测量频次：电压内阻测量使用1KHz规格，预处理后，测试后测量；
⑤判定标准：不起火，不爆炸，不冒烟。
循环性能测试
循环前的准备过程：在测试温度为25℃的条件下静置30min，接着以0.2C的电流密度放电至3V；
再静置30min，以0.5C恒流充电至4.48V,恒压充电至0.02C；静置30min；以0.2C的电流密度放电至3V，最后静置30min。
循环流程
测试过程：在测试温度为25℃的条件下静置30min，接着以12.4A恒流充电至4.22V,恒压充电至1.8C；接着以1.8C恒流充电C至4.3V,恒压充电至1.5C；以1.5C恒流充电C至4.48V,恒压充电至1.2C；以1.2C恒流充电C至4.53V,恒压充电至0.26C；静置5min，以0.7C的电流密度放电至3.2V；静置5min，以第3步到第9步循环800次。
高温循环测试如上，仅是将温度条件设置为45℃。
溶胀度测试方法
制备胶膜：拆解电芯，取出隔膜，长宽大于10cm的，溶于有机溶剂NMP中，溶剂与溶液比例为1：9，将盛有上述悬浮液的烧杯，置于分散机上搅拌，充分搅拌1.5h。将搅拌后的溶液，静置30min，消除气泡。使用滤网过滤，去除不溶的杂质以及基膜。将此溶液倒入胶膜制备模具中，若有气泡提前去除。将模具放入烘箱中，设定温度为60℃，时间为12h。
将制备好的胶膜用剪刀裁成2g左右的小条，每种胶膜做2～3平行样；将胶膜小条分别称重，记录初始重量M1，放入小瓶中，标识好样品名称，加入电解液，超过胶膜2-3cm，密封好小瓶，放入烘箱中，设置温度60℃测试溶胀时间24h。测试时将胶膜取出，用无尘纸擦拭干净，记录每个时间的胶膜重量M2。
溶胀度＝(M2-M1)/M1
表一

依据表一中的测试结果可知：实施例1-1至实施例1-21的电池的热箱测试通过率均能达到80％及以上且均明显高于对比例1-2至对比例1-4的电池的热箱测试通过率，实施例1-1至实施例1-21的电池的常温循环测试25℃4C 800周次的容量保持率均能达到 80％及以上。可知，通过采用本申请中含有低熔点的第一聚合物和低溶胀度的第二聚合物的有机涂层，可在保证电池的常温循环性能的基础上，有效提升电池的热箱测试通过率。
第二组实施例有机涂层制备
第二组实施例按照下面表二中的第一聚合物和第二聚合物的参数并添加辅助组分(增稠剂为羧甲基纤维素钠，润湿剂为磺酸盐和二甲基硅烷)配比制备有机涂层，其中第一聚合物65重量份、第二聚合物30重量份、辅助组分5重量份，然后加入去离子水进行搅拌，调整浆料的粘度为50mPa·s，固含量5％，得到浆料A。将上述浆料A均匀地涂布在PE基膜的无机涂层表面上，得到第一涂层，第一涂层的涂布重量0.2g/m2，在烘箱中完成干燥。电解液中相应的增大环状羧酸酯(如EC)的占比以满足下述线性羧酸酯含量的调控。
第二组实施例的其他步骤和参数请参上述第一组实施例的步骤和参数，最终制得锂离子电池。
表二
依据表二中的测试结果可知：第二聚合物的溶胀度D和电解液中线性羧酸酯的含量H，满足公式D＝K*H+0.1，其中0.01≤K≤0.08；通过控制电解液中合理的线性羧酸酯的含量并搭配对第二聚合物合适的溶胀度，可提升电池的高温循环性能。
第三组实施例有机涂层制备
第三组实施例按照下面表三中的第一聚合物和第二聚合物的参数并添加辅助组分(增稠剂为羧甲基纤维素钠，润湿剂为磺酸盐和二甲基硅烷)配比制备有机涂层，其中第一聚合物65重量份、第二聚合物30重量份、辅助组分5重量份，然后加入去离子水 进行搅拌，调整浆料的粘度为50mPa·s，固含量5％，得到浆料A。将上述浆料A均匀地涂布在PE基膜的无机涂层表面上，得到第一涂层，第一涂层的涂布重量0.2g/m2，在烘箱中完成干燥。
第三组实施例的其他步骤和参数请参上述第一组实施例的步骤和参数，最终制得锂离子电池。
表三
依据表三中的测试结果可知：通过设置第二聚合物较高的球形度和较低的溶胀度(85℃)，有利于提升电池的倍率性能。
需要说明的是，以上仅为本申请的具体实施方式，但本申请的保护范围并不局限于此，任何熟悉本技术领域的技术人员在本申请揭露的技术范围内，可轻易想到变化或替换，都应涵盖在本申请的保护范围之内；在不冲突的情况下，本申请的实施方式及实施方式中的特征可以相互组合。因此，本申请的保护范围应以权利要求的保护范围为准。

Claims (16)

  1. 一种隔离膜，其特征在于，包括：
    基膜；
    有机涂层，设置在所述基膜的一表面上，所述有机涂层含有第一聚合物和第二聚合物；
    所述第一聚合物的熔点T满足60℃≤T≤100℃；
    所述第二聚合物在溶液中于60℃放置24h的溶胀度D≤30％，所述溶液的六氟磷酸锂、碳酸乙烯酯、碳酸二乙酯、碳酸亚丙酯、丙酸丙酯的质量比为8.7：20：30：20：30。
  2. 根据权利要求1所述的隔离膜，其特征在于，所述第一聚合物的中值粒径Dv50满足0.5μm＜Dv50＜2μm。
  3. 根据权利要求1所述的隔离膜，其特征在于，在所述有机涂层中，所述第一聚合物的重量百分含量大于等于40％且小于等于95％，所述第二聚合物的重量百分含量小于等于50％。
  4. 根据权利要求1所述的隔离膜，其特征在于，在所述有机涂层中，所述第一聚合物的重量百分含量大于等于60％且小于等于95％，所述第二聚合物的重量百分含量小于等于30％。
  5. 根据权利要求1所述的隔离膜，其特征在于，当将所述隔离膜应用于电化学电池电芯中，所述第二聚合物的溶胀度D和电解液中线性羧酸酯的含量H，满足D＝K*H+0.1，其中0.01≤K≤0.08。
  6. 根据权利要求5所述的隔离膜，其特征在于，10％≤H≤50％。
  7. 根据权利要求1所述的隔离膜，其特征在于，所述第一聚合物的中值粒径Dv50满足1.0μm≤Dv50≤2μm。
  8. 根据权利要求1所述的隔离膜，其特征在于，所述第一聚合物的熔点T满足60℃≤T≤85℃。
  9. 根据权利要求1所述的隔离膜，其特征在于，所述第二聚合物呈球形或类球形，所述第二聚合物的球形度R满足0.7≤R＜1。
  10. 根据权利要求1所述的隔离膜，其特征在于，所述第二聚合物呈球形或类球形，所述第二聚合物的球形度R满足0.8≤R＜1。
  11. 根据权利要求1所述的隔离膜，其特征在于，所述第二聚合物在电解液中于85℃放置24h的溶胀度D满足10％≤D≤50％。
  12. 根据权利要求1所述的隔离膜，其特征在于，所述第一聚合物包括接枝共聚物，所述接枝共聚物中的聚合物主体的单体包括乙烯、丙烯、偏氟乙烯、丙烯酸、丙烯酸酯、苯乙烯、丙烯腈、马来酸酐、氯乙烯和氯丙烯中的至少一种，用于接枝的单体包括马来酸酐、丙烯酸酯和丙烯酸中的至少一种；所述接枝共聚物在所述第一聚合物中的重量百分含量为大于等于3％且小于等于10％。
  13. 根据权利要求1所述的隔离膜，其特征在于，所述第二聚合物包括偏氟乙烯、六氟丙烯、丙烯、氯乙烯、苯乙烯、丁二烯、丙烯酸酯、丙烯酸中的至少一种单体的聚合物，所述第二聚合物为均聚物、共聚物和共混聚合物中的至少一种。
  14. 一种二次电池，其包括正极极片、负极极片以及设置在所述正极极片和所述负极极片之间的隔离膜，其特征在于，所述隔离膜为如权利要求1至13中任一项所述的隔离膜，其中所述有机涂层位于所述正极极片和所述基膜之间。
  15. 一种电化学装置，其包括正极极片、负极极片以及设置在所述正极极片和所述负极 极片之间的隔离膜，其特征在于，所述隔离膜为如权利要求1至13中任一项所述的隔离膜，其中所述有机涂层位于所述正极极片和所述基膜之间。
  16. 一种用电装置，其特征在于，包括权利要求15所述的电化学装置或权利要求14所述的二次电池。
PCT/CN2023/112469 2023-08-11 2023-08-11 隔离膜、二次电池、电化学装置和用电装置 Pending WO2025035243A1 (zh)

Priority Applications (2)

Application Number Priority Date Filing Date Title
CN202380036692.2A CN119072820A (zh) 2023-08-11 2023-08-11 隔离膜、二次电池、电化学装置和用电装置
PCT/CN2023/112469 WO2025035243A1 (zh) 2023-08-11 2023-08-11 隔离膜、二次电池、电化学装置和用电装置

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/CN2023/112469 WO2025035243A1 (zh) 2023-08-11 2023-08-11 隔离膜、二次电池、电化学装置和用电装置

Publications (1)

Publication Number Publication Date
WO2025035243A1 true WO2025035243A1 (zh) 2025-02-20

Family

ID=93638125

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/CN2023/112469 Pending WO2025035243A1 (zh) 2023-08-11 2023-08-11 隔离膜、二次电池、电化学装置和用电装置

Country Status (2)

Country Link
CN (1) CN119072820A (zh)
WO (1) WO2025035243A1 (zh)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN121394777A (zh) * 2025-12-23 2026-01-23 比亚迪股份有限公司 一种隔膜、二次电池、电池组、电子设备

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114144932A (zh) * 2021-03-31 2022-03-04 宁德新能源科技有限公司 一种隔离膜及包含所述隔离膜的电化学装置和电子装置
CN114175384A (zh) * 2021-03-31 2022-03-11 宁德新能源科技有限公司 隔离膜及包含该隔离膜的电化学装置和电子装置
WO2022205156A1 (zh) * 2021-03-31 2022-10-06 宁德新能源科技有限公司 一种隔离膜及包含该隔离膜的电化学装置和电子装置
CN115810873A (zh) * 2022-10-24 2023-03-17 宁德时代新能源科技股份有限公司 电池组件、电池单体、二次电池和用电装置
WO2023123220A1 (zh) * 2021-12-30 2023-07-06 宁德时代新能源科技股份有限公司 一种隔离膜及包含其的二次电池、电池模块、电池包和装置

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SU960200A1 (ru) * 1981-02-27 1982-09-23 за вители всесошзм 1 ivyspbHRTEHTtiu « 4 1.1 id I 1 « ТЕХНИЛБСКЛЯ БИБЛИОТЕКА Способ изготовлени полимерной пленки,флуоресцирующей в ультрафиолетовом свете
JP2008027839A (ja) * 2006-07-25 2008-02-07 Hitachi Maxell Ltd ライナー付き多孔質膜、多孔質膜の製造方法、およびリチウム二次電池の製造方法
CN107123767B (zh) * 2017-04-20 2020-04-03 深圳市旭然电子有限公司 一种有机功能化多孔性隔离膜、制备方法及锂离子电池
CN110729440B (zh) * 2019-09-29 2023-02-17 深圳中兴新材技术股份有限公司 一种锂离子电池涂层隔膜、制备方法及锂离子电池

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114144932A (zh) * 2021-03-31 2022-03-04 宁德新能源科技有限公司 一种隔离膜及包含所述隔离膜的电化学装置和电子装置
CN114175384A (zh) * 2021-03-31 2022-03-11 宁德新能源科技有限公司 隔离膜及包含该隔离膜的电化学装置和电子装置
WO2022205156A1 (zh) * 2021-03-31 2022-10-06 宁德新能源科技有限公司 一种隔离膜及包含该隔离膜的电化学装置和电子装置
WO2023123220A1 (zh) * 2021-12-30 2023-07-06 宁德时代新能源科技股份有限公司 一种隔离膜及包含其的二次电池、电池模块、电池包和装置
CN115810873A (zh) * 2022-10-24 2023-03-17 宁德时代新能源科技股份有限公司 电池组件、电池单体、二次电池和用电装置

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN121394777A (zh) * 2025-12-23 2026-01-23 比亚迪股份有限公司 一种隔膜、二次电池、电池组、电子设备

Also Published As

Publication number Publication date
CN119072820A (zh) 2024-12-03

Similar Documents

Publication Publication Date Title
JP7776523B2 (ja) セパレータならびに前記セパレータを含む電気化学装置および電子装置
TWI376828B (en) Electrolytic solution and lithium battery employing the same
WO2022205156A1 (zh) 一种隔离膜及包含该隔离膜的电化学装置和电子装置
WO2022205163A1 (zh) 隔离膜及包含该隔离膜的电化学装置和电子装置
CN113728504B (zh) 聚合物粘结剂、叠层多孔膜、电池及电子装置
WO2022206151A1 (zh) 负极极片及包含该负极极片的电化学装置、电子装置
CN103311500A (zh) 一种锂离子电池负极极片及制作方法
CN117458084B (zh) 一种二次电池和电子装置
WO2023155604A1 (zh) 复合隔膜及电化学装置
WO2021108984A1 (zh) 二次电池、包括该二次电池的装置、二次电池的制备方法及粘结剂组合物
WO2022141508A1 (zh) 一种电化学装置和电子装置
CN115832640A (zh) 负极极片及其制备方法、二次电池及其制备方法、电池模块、电池包和用电装置
WO2023184416A1 (zh) 一种隔膜、包含该隔膜的电化学装置及电子装置
JP2024535875A (ja) セパレータ、その製造方法及び二次電池、電池モジュール、電池パックと電力消費装置
WO2023015521A1 (zh) 隔离膜、锂离子电池、电池模块、电池包和用电装置
US20260011869A1 (en) Secondary battery and electronic device
WO2023184208A1 (zh) 一种粘结剂、电化学装置和电子装置
CN115117358A (zh) 含氟聚合物、其制备方法和用途、正极浆料、二次电池、电池模块、电池包及用电装置
CN115820064A (zh) 涂料组合物、隔离膜、二次电池、电池模块、电池包和用电装置
CN117913465A (zh) 隔膜及其制备方法、二次电池和用电装置
WO2024046274A1 (zh) 正极极片、二次电池及用电装置
CN116666732A (zh) 一种二次电池及电子装置
WO2025035243A1 (zh) 隔离膜、二次电池、电化学装置和用电装置
CN118476064A (zh) 用于正极极片的水性粘接剂以及由其制备的正极极片
WO2024045126A1 (zh) 一种粘结剂、隔膜及使用该隔膜的锂离子电池

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 23948688

Country of ref document: EP

Kind code of ref document: A1

REG Reference to national code

Ref country code: BR

Ref legal event code: B01A

Ref document number: 112026003384

Country of ref document: BR

WWE Wipo information: entry into national phase

Ref document number: 2023948688

Country of ref document: EP

NENP Non-entry into the national phase

Ref country code: DE