WO2023078409A1 - 一种隔膜和含有该隔膜的锂离子电池 - Google Patents

一种隔膜和含有该隔膜的锂离子电池 Download PDF

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Publication number
WO2023078409A1
WO2023078409A1 PCT/CN2022/129949 CN2022129949W WO2023078409A1 WO 2023078409 A1 WO2023078409 A1 WO 2023078409A1 CN 2022129949 W CN2022129949 W CN 2022129949W WO 2023078409 A1 WO2023078409 A1 WO 2023078409A1
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Prior art keywords
diaphragm
coating
additive
separator
organic matter
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PCT/CN2022/129949
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English (en)
French (fr)
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赵君义
李素丽
李俊义
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珠海冠宇电池股份有限公司
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Publication of WO2023078409A1 publication Critical patent/WO2023078409A1/zh

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • 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
    • H01M50/403—Manufacturing processes of separators, membranes or diaphragms
    • 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
    • H01M50/417—Polyolefins
    • 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 disclosure belongs to the technical field of diaphragms, and in particular relates to a diaphragm and a lithium ion battery containing the diaphragm.
  • the currently used separator is a porous polyolefin product (such as PE, PP, PP/PE/PP three layers), and the single or double sides of the substrate separator are coated with inorganic particles (for example: alumina, boehmite, Magnesium oxide, magnesium hydroxide, etc.), on this basis, one-sided or double-sided pure glue or glue and ceramic particles mixed coating (the glue can be a single PVDF or a mixture of multiple PVDF products), coated As the method, water-based coating and oil-based coating can be used.
  • inorganic particles for example: alumina, boehmite, Magnesium oxide, magnesium hydroxide, etc.
  • glue can be a single PVDF or a mixture of multiple PVDF products
  • the water-based diaphragm refers to the finished product obtained by dispersing a single variety or multiple PVDFs in water, grinding them to form a suspension, filtering them, and coating them.
  • the coating method can be micro-gravure roller transfer coating or spray coating.
  • the oil-based diaphragm refers to a single type or a variety of PVDF dissolved in an organic solvent (such as NMP, DMAC/acetone, etc.) at a certain ratio (m:n, m, n can be a number from 0 to 10) and coated.
  • the finished product can be coated by micro-gravure roll transfer coating or direct dip coating.
  • the electrostatic value of the surface of the diaphragm is different.
  • the electrostatic value of the water-based diaphragm is ⁇ 300V
  • the electrostatic value of the single-sided ceramic and double-sided oil-based product is about 1000V
  • the mixed-coated double-sided ceramic and glue The electrostatic value of the diaphragm is as high as 3000V above or greater.
  • Such diaphragms often have relatively large static electricity in the process of preparing lithium-ion batteries, which can absorb tiny particles in the air, so that the inside of the battery cell of the lithium-ion battery is in a micro-short circuit state (such as the voltage drop of the battery cell is very obvious, The maximum value can reach 0.1mV/h or more).
  • the present disclosure introduces additives into the diaphragm, the additive forms a structure with low static electricity on the surface of the diaphragm, reduces the static value of the diaphragm, and can have low static electricity and high manufacturing process without reducing the adhesion between the diaphragm and the electrode sheet. Capabilities, such as the high yield rate of the battery, the proportion of defective core pulling and Hi-Pot defects can be kept at a low level.
  • a diaphragm the diaphragm includes a diaphragm coating; the diaphragm coating contains a first additive and a second additive, and the mass ratio (g:g) of the first additive to the second additive is 1:9 ⁇ 9:1; the membrane coating includes several glue layer holes, and the diameter of the glue layer holes is 0.01 ⁇ m ⁇ 10 ⁇ m.
  • the mass ratio (g:g) of the first additive to the second additive is 2:8 ⁇ 8:2.
  • the holes in the glue layer with a diameter in the range of 1 ⁇ m to 3 ⁇ m account for 30% to 70% of the total number of holes in the glue layer.
  • the second additive is an organic microsphere, and the organic microsphere satisfies at least one of the following conditions:
  • the weight average molecular weight of the organic matter in the organic matter microspheres is 5 ⁇ 10 5 Da ⁇ 30 ⁇ 10 5 Da;
  • the average particle diameter D50 of the organic microspheres is 0.1 ⁇ m to 300 ⁇ m;
  • the melting point of the organic matter in the organic matter microspheres is 100°C to 200°C;
  • the organic matter in the organic matter microspheres is selected from at least one of fluorine-containing polymers or acrylic polymers;
  • the organic matter in the organic matter microsphere is selected from at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE) or polymethyl methacrylate (PMMA).
  • PVDF polyvinylidene fluoride
  • PTFE polytetrafluoroethylene
  • PMMA polymethyl methacrylate
  • the first additive is connected to the surface of the second additive in a long-chain grid.
  • the first additive is selected from PVDF, which has a melting point of 150° C. to 160° C. and a weight average molecular weight of 3 ⁇ 10 5 Da to 7 ⁇ 10 5 Da.
  • the separator includes a substrate separator and the separator coating on at least one surface of the substrate separator, and the thickness of the separator coating is 0.1 ⁇ m ⁇ 3 ⁇ m.
  • the membrane coating when the membrane coating is disposed on both surfaces of the substrate membrane, the membrane includes 2 membrane coatings, and the total thickness of the 2 membrane coatings is 0.2 ⁇ m ⁇ 5 ⁇ m.
  • the thickness of the substrate separator is 1 ⁇ m ⁇ 30 ⁇ m.
  • the substrate separator is selected from a single-layer substrate separator or a multi-layer substrate separator composed of PE and/or PP.
  • the diaphragm is an oil-based diaphragm.
  • the average electrostatic value of the separator is less than 1500V.
  • the average self-discharge of the diaphragm is less than 0.045mV/h.
  • the present disclosure also provides a lithium ion battery, which includes the above-mentioned separator.
  • the disclosure introduces the second additive organic matter on the surface of the diaphragm, so that the organic matter can partially cross-link with the first additive in the solvent system, and at the same time, most of the second additive organic matter still maintains the original complete form and can form with the first additive.
  • Ball connection phenomenon the small balls can be connected on the surface of different spheres to form a multi-layer honeycomb structure, which can form many and large giant mesh structures, so that the electrostatic value of the oil-based diaphragm or oil-based mixed coating diaphragm is significantly reduced. For example, drop from 3000V or higher to less than 1200V.
  • the present disclosure can reduce the electrostatic adsorption capacity of the surface of the oil-based/oil-based mixed-coated diaphragm, thereby reducing the adsorption of tiny particles and reducing the self-discharge value of the battery cell, thereby improving the quality of the battery cell.
  • the present disclosure introduces the organic microspheres of the second additive and the first additive to form a mesh structure on the surface of the diaphragm.
  • the diaphragm of the present disclosure can be used to replace the ceramic particles currently introduced in the diaphragm coating, thereby reducing the surface energy of the diaphragm surface coating. , The purpose of reducing the static electricity on the surface of the diaphragm.
  • Fig. 1 is the schematic diagram of the organic matter of the present disclosure in the coating; Wherein, the black ball represents the first additive organic matter; The line represents the second additive of the membrane surface coating;
  • Fig. 2 is the SEM figure of the diaphragm surface of embodiment 1;
  • Fig. 3 is the SEM figure of the diaphragm surface of embodiment 2;
  • Fig. 4 is the SEM picture of the membrane surface of embodiment 3;
  • Fig. 5 is the SEM picture of the diaphragm surface of embodiment 4.
  • Fig. 6 is the SEM figure of the diaphragm surface of comparative example 1;
  • Fig. 7 is a schematic diagram of core-pulling; 1-core; 2-tab; 3-diaphragm.
  • the present disclosure provides a diaphragm coating, which contains a first additive and a second additive; the diaphragm coating includes several adhesive layer holes, and the diameter of the adhesive layer holes is 0.01 ⁇ m ⁇ 10 ⁇ m.
  • the first additive and the second additive form a multi-angle interconnected network structure in the membrane coating, and the network structure includes the plurality of adhesive layer holes. Specifically, as shown in FIG. 2 or FIG. 3 .
  • the number of glue line holes with a diameter in the range of 1 ⁇ m ⁇ 3 ⁇ m accounts for 30% ⁇ 70% of the total number of glue line holes.
  • the reason for choosing such a pore size, especially such a pore size distribution, is that such a pore size distribution can form a layered and porous distribution, which can increase the specific surface area of the oil-based diaphragm, thereby reducing the electrostatic generation of the diaphragm during coating, slitting, and use.
  • the electrostatic value of the diaphragm is obviously high (>2000V), which is not conducive to production.
  • the adhesive force between the adhesive layer and the electrode piece will be weakened, so the range of 30% to 70% is selected.
  • the second additive is organic microspheres
  • the weight average molecular weight of the organic matter in the organic microspheres is 5 ⁇ 10 5 Da to 30 ⁇ 10 5 Da, for example, it may be 5 ⁇ 10 5 Da. 10 5 Da, 6 ⁇ 10 5 Da, 7 ⁇ 10 5 Da, 8 ⁇ 10 5 Da, 8.5 ⁇ 10 5 Da, 9 ⁇ 10 5 Da, 10 ⁇ 10 5 Da, 11 ⁇ 10 5 Da, 12 ⁇ 10 5 Da, 13 ⁇ 10 5 Da, 14 ⁇ 10 5 Da, 15 ⁇ 10 5 Da, 20 ⁇ 10 5 Da, 30 ⁇ 10 5 Da.
  • the weight average molecular weight of the organic matter in the organic matter microspheres is 8 ⁇ 10 5 Da to 10 ⁇ 10 5 Da or 10 ⁇ 10 5 Da to 30 ⁇ 10 5 Da.
  • the average particle diameter D50 of the organic microspheres is 0.1 ⁇ m to 300 ⁇ m, such as 0.1 ⁇ m, 0.3 ⁇ m, 1 ⁇ m, 2 ⁇ m, 3 ⁇ m, 3.5 ⁇ m, 3.724 ⁇ m, 4 ⁇ m, 5 ⁇ m, 10 ⁇ m, 50 ⁇ m, 100 ⁇ m, 200 ⁇ m or 300 ⁇ m.
  • the average particle diameter D50 of the organic microspheres is 0.3 ⁇ m ⁇ 10 ⁇ m, specifically 0.3 ⁇ m ⁇ 5 ⁇ m.
  • microspheres with such a particle size distribution are selected microspheres with such a particle size distribution.
  • the melting point of the organic matter in the organic matter microspheres is 100°C to 200°C, specifically, the melting point may be 100°C, 110°C, 120°C, 130°C, 140°C, 145°C, 150°C , 155°C, 160°C, 170°C, 180°C, 190°C or 200°C; Exemplarily, the melting point is 140°C-155°C.
  • the melting point of the organic compound is too low, the glass transition temperature of the organic compound is low, which is not conducive to the application of the separator; when the melting point of the organic compound is too high, the crystallization of the organic compound is too high, which is not conducive to the formation of a network structure.
  • the organic matter in the organic matter microspheres is selected from at least one of fluorine-containing polymers or acrylic polymers, and the organic matter microspheres are partially dissolved or dissolved in an organic solvent (such as NMP or DMAC), thereby becoming the basis of the above-mentioned network structure, and further forming the above-mentioned network structure through the interconnection of the first additive.
  • an organic solvent such as NMP or DMAC
  • the organic matter in the organic matter microsphere is selected from at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE) or polymethyl methacrylate (PMMA).
  • PVDF polyvinylidene fluoride
  • PTFE polytetrafluoroethylene
  • PMMA polymethyl methacrylate
  • the organic matter in the organic matter microsphere is selected from PVDF, which has the properties of the above-mentioned organic matter, such as weight average molecular weight and melting point.
  • the first additive is selected from organic matter, and the organic matter includes the organic matter in the organic matter microspheres of the second additive; the first additive is connected to the second additive (such as Organic microspheres) surface, thereby forming the mesh structure.
  • the first additive is selected from PVDF, the melting point of which is 150°C-160°C, and the weight-average molecular weight is 3 ⁇ 10 5 Da-7 ⁇ 10 5 Da.
  • the mass ratio (g:g) of the first additive to the second additive is 1:9-9:1, specifically, it can be matched according to the solubility or molecular weight of the two, for example 1:9, 2:8, 3:7, 4:6, 5:5, 6:4, 7:3, 8:2 or 9:1.
  • the above mesh structure is obtained by adjusting the mass ratio of the first additive to the second additive. If only the second additive is added, it is not conducive to the formation of the above-mentioned network structure.
  • a mass ratio (g:g) of the first additive to the second additive is 2:8 ⁇ 8:2.
  • the present disclosure also provides a separator, which includes the above-mentioned separator coating.
  • the separator includes a substrate separator and the above-mentioned separator coating disposed on at least one surface of the substrate separator.
  • the separator when the separator coating is provided on one surface of the substrate separator, the separator includes one separator coating, and the thickness of one separator coating is 0.1 ⁇ m to 0.1 ⁇ m. 3 ⁇ m, for example, 0.8 ⁇ m to 1.2 ⁇ m.
  • the diaphragm coating when the diaphragm coating is disposed on both surfaces of the substrate diaphragm, the diaphragm includes 2 diaphragm coatings, and the total thickness of the 2 diaphragm coatings is 0.2 ⁇ m to 5 ⁇ m, for example, 1.8 ⁇ m to 2.2 ⁇ m.
  • the substrate separator is selected from a single-layer substrate separator or a multi-layer substrate separator composed of PE and/or PP.
  • the substrate separator is selected from a three-layer substrate separator of PP/PE/PP.
  • the second additive forms a stable skeleton support in the diaphragm coating (as shown in FIG. 1 ), which can protrude the diaphragm coating on the diaphragm surface, thereby forming a stable skeleton support in the diaphragm coating.
  • Adhesive layer holes are formed on the surface, and the interconnection of the adhesive layer holes through the first additive forms the mesh structure, as specifically shown in FIG. 2 or FIG. 3 .
  • the substrate separator has a thickness of 1 ⁇ m ⁇ 30 ⁇ m.
  • the diaphragm is an oil-based diaphragm.
  • the average electrostatic value of the separator is less than 1500V.
  • the average self-discharge of the separator is less than 0.045 mV/h.
  • the inventors found that when the separator with such a self-discharge value is applied to a battery cell, the long-term storage performance of a single battery cell is good, the series voltage difference of multiple batteries is small, and the failure rate of the battery cells is reduced.
  • the separator is not easy to attract light and small objects during use, which can reduce the probability of foreign objects entering the cell body.
  • the present disclosure also provides a lithium ion battery including the above separator.
  • the lithium ion battery further includes a positive electrode.
  • the positive electrode includes at least a positive electrode current collector, a positive electrode coating, and a tab.
  • the positive electrode current collector is selected from aluminum foil, and the thickness of the aluminum foil is 8 ⁇ m ⁇ 14 ⁇ m.
  • the positive electrode coating includes a positive electrode active material, a positive electrode conductive agent, and a positive electrode binder.
  • the positive electrode active material is at least one selected from LiCoO 2 , LiNiO 2 , LiFePO 4 , LiMn 2 O 4 or LiNix Co y Mn 1-xy O 2 .
  • the positive electrode conductive agent is selected from at least one of conductive carbon black, carbon nanotubes, conductive graphite or graphene.
  • the positive electrode binder is selected from polyvinylidene fluoride, a copolymer of vinylidene fluoride-fluorinated olefin, polytetrafluoroethylene, sodium carboxymethyl cellulose, styrene-butadiene rubber, polyurethane, At least one of fluorinated rubber or polyvinyl alcohol.
  • the mass fraction of the positive electrode active material is 96% to 98.5%
  • the mass fraction of the positive electrode conductive agent is 0.5% to 2.5%
  • the positive electrode binder The mass fraction is 1% to 1.5%.
  • the lithium ion battery further includes a negative electrode.
  • the negative electrode includes a negative electrode current collector, a negative electrode coating, and a tab.
  • the negative electrode coating includes a negative electrode active material, a negative electrode conductive agent, a negative electrode binder, and a dispersant.
  • the negative electrode active material is selected from at least one of mesophase carbon microspheres, artificial graphite, natural graphite, hard carbon, soft carbon, lithium titanate, silicon-based materials, tin-based materials or lithium metal. kind.
  • the negative electrode conductive agent is selected from at least one of conductive carbon black, carbon nanotubes, conductive graphite or graphene.
  • the negative electrode binder is selected from polyvinylidene fluoride, a copolymer of vinylidene fluoride-fluorinated olefin, polytetrafluoroethylene, sodium carboxymethyl cellulose, styrene-butadiene rubber, polyurethane, At least one of fluorinated rubber and polyvinyl alcohol.
  • the dispersant is selected from sodium carboxymethylcellulose and/or potassium carboxymethylcellulose.
  • the mass fraction of the negative electrode active material is 95% to 97%
  • the mass fraction of the negative electrode conductive agent is 1.0% to 2%
  • the negative electrode binder The mass fraction of the dispersant is 1% to 1.5%, and the mass fraction of the dispersant is 0% to 1.5%.
  • DMAC refers to dimethylacetamide
  • DMF refers to N,N-dimethylformamide
  • the second additive used in the following comparative examples and examples is polyvinylidene fluoride (PVDF) microspheres, wherein the melting point of PVDF is 145 ⁇ 5°C, and the weight average molecular weight is between 8 ⁇ 10 5 Da ⁇ 10 ⁇ 10 5 Da
  • the average particle diameter D50 of the microspheres was 3.724 ⁇ m.
  • the first additive is conventional PVDF, its melting point is 150°C-160°C, and its weight-average molecular weight is between 3 ⁇ 10 5 Da and 7 ⁇ 10 5 Da.
  • the electrostatic value in this disclosure is obtained by Keyence SK-H050 test.
  • the average value of the electrostatic value calculated for each group of separators is the average value of the electrostatic value.
  • the diaphragm substrate is PE with a thickness of 5 ⁇ m; the solid content of the coating slurry is 7.5%, and the solvent is DMAC; among them, PVDF accounts for 37.5% , wherein the second additive PVDF is added to the coating slurry according to 10% of the total amount of PVDF for stirring, the stirring time is 30min, the viscosity of the slurry is controlled at 130-180mPa ⁇ s, and the coating is double-sided coating, 2 coats The total thickness was 2 ⁇ m, and the oily separator 1 was obtained after coating.
  • the preparation method of the membrane of this embodiment is the same as that of Example 1, except that the second additive PVDF microspheres accounts for 30% of the total mass of PVDF, and an oily isolation membrane 2 is obtained. Measure its surface electrostatic value and record it in Table 1.
  • the preparation method of the membrane of this embodiment is the same as that of Example 1, except that the second additive PVDF microspheres accounts for 50% of the total mass of PVDF, and an oily isolation membrane 3 is obtained. Measure its surface electrostatic value and record it in Table 1.
  • the preparation method of the membrane of this embodiment is the same as that of Example 1, except that the second additive PVDF microspheres accounts for 70% of the total mass of PVDF, and an oily isolation membrane 4 is obtained. Measure its surface electrostatic value and record it in Table 1.
  • the solid content is 7.5%
  • the solvent is DMAC
  • the first additive is conventional PVDF, which accounts for 37.5% of the total solid mass, and the viscosity of the solution is 130-180 mPa ⁇ s.
  • the coating thickness is double-sided coating, the total thickness of the two coatings is 2 ⁇ m, and the oily separator 5 is obtained after coating.
  • Fig. 2-Fig. 5 it is the SEM figure of the membrane surface of embodiment 1-4, it can be seen from the SEM figure that the membrane surface forms a mesh structure as shown in Fig. 2-Fig. Connection, the organic matter can be partially swelled in the organic solvent (in) or dissolved in high temperature and long time soaking, when the partial dissolution occurs, the organic matter can be connected to the dissolved PVDF component in the solvent around the ball, forming a unique shape Topography (such as the skeleton support structure shown in Figure 1), which has a porous and specific skeleton structure. Observe and record the pore size distribution of the diaphragm coating in Table 1 from the SEM images of the diaphragm surface in Fig. 2-Fig. 5, wherein the pore diameter refers to the diameter of the surface hole formed, and is calculated according to the long axis direction when the hole is elliptical.
  • Figure 6 shows the SEM image of the membrane surface of Comparative Example 1. It can be seen from the SEM image that the membrane surface has no mesh structure, and the pore size distribution of the membrane surface is recorded in Table 1.
  • Diaphragm 1-5 prepared in Comparative Example 1 and Example 1-4 were selected respectively;
  • Positive electrode structure foil material is aluminum foil, 10 ⁇ m; positive electrode coating includes: positive electrode active material is LiCoO 2 , accounting for 97.80%; positive electrode conductive agent is conductive carbon black, accounting for 1.10%; positive electrode binder is polyvinylidene fluoride , accounting for 1.10%;
  • Negative electrode structure foil material is copper foil, 5 ⁇ m; negative electrode coating includes: negative electrode active material is mesophase carbon microspheres, accounting for 96.50%, negative electrode conductive agent is carbon nanotubes, accounting for 0.90%, negative electrode binder is SBR , accounting for 1.30%, the dispersant is sodium carboxymethylcellulose/CMC, accounting for 1.30%;
  • the above-mentioned separators 1-5 were assembled with the above-mentioned positive electrode and negative electrode respectively to form a pouch battery, which was designated as battery 1-5.
  • Cell self-discharge test method take 32PCS of the batteries 1-5 of the above-mentioned examples 1-4 and comparative example 1, respectively, and perform a chemical conversion activation or capacity screening, then aging at 45°C for 48h, and then take it out and let it stand for 24h at room temperature
  • the last time to test the cell voltage V1 is recorded as t1
  • the second voltage test is recorded as V2 after 48 hours, and the time is recorded as t2
  • the self-discharge value K of the cell (in mV/h) is:
  • K (V1-V2)/(t2-t1); the average value calculated from the K value of each group of batteries is the average self-discharge value, which is recorded in Table 1.
  • the diaphragms of the above-mentioned Examples 1-4 and Comparative Example 1 are grouped for production and use in the cell winding process, and each group follows up with a production capacity of 3000pcs.
  • the core-pulling phenomenon refers to the innermost ring of the diaphragm and the winding needle during the winding process. Direct contact, when the winding needle is pulled out, the electrostatic adsorption or dynamic friction between the diaphragm and the winding needle will cause the diaphragm to be pulled out of the winding core, causing the winding core to pull out, as shown in Figure 7.
  • a represents the length of the part of the diaphragm exposed outside the core, that is, a represents the core-pulling distance of the core, in millimeters.
  • a represents the core-pulling distance of the core, in millimeters.
  • the batteries 1-5 of the above-mentioned embodiments 1-4 and comparative example 1 were respectively divided into 3000PCS groups and used for this test, and the Hi-Pot test was carried out on an insulation resistance tester (model: HIOKI ST5520), and the test conditions were: voltage 100V , time 2.5s, surface pressure: 0.2Mpa, when the resistance value > 2M ⁇ , it is marked as qualified, when the resistance value is ⁇ 2M ⁇ , it is marked as unqualified.
  • Hi-Pot defective rate the number of unqualified batteries in each group/3000, and the calculation results are recorded in Table 1.
  • the diaphragm adhesive layer of the present disclosure can effectively reduce the electrostatic value of the diaphragm coating, reduce the ability of the diaphragm surface to absorb light and small objects/particles, and achieve the effect of reducing the self-discharge of the battery core.
  • the formed mesh structure is obvious and the surface static value is significantly reduced.
  • the method can change the surface morphology of the gravure oil-based diaphragm by adding a certain amount of second additive organic matter, reduce the surface static value, and increase the manufacturability of the diaphragm at the same time.
  • the organic microspheres of the second additive and the first additive are introduced on the surface of the membrane to form a network structure, which can be used to replace the ceramic particles currently introduced in the membrane adhesive layer.

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Abstract

本公开提供一种隔膜和含有该隔膜的锂离子电池，所述隔膜包括隔膜涂层；所述隔膜涂层中含有第一添加剂和第二添加剂，所述第一添加剂与第二添加剂的质量比(g；g)为1:9～9:1；所述隔膜涂层包括若干胶层孔，所述胶层孔的孔径为0.01μm～10μm。本公开通过降低油系/油系混涂的隔膜表面的静电吸附能力，能够减少吸附微小颗粒，降低电芯的自放电值，从而提高电芯质量。

Description

一种隔膜和含有该隔膜的锂离子电池 技术领域
本公开属于隔膜技术领域，特别是涉及一种隔膜和含有该隔膜的锂离子电池。
背景技术
目前使用的隔膜是具有多孔的聚烯烃产品(例如PE、PP、PP/PE/PP三层)，该基材隔膜的单面或者双面涂有无机粒子(例如：氧化铝，勃母石，氧化镁，氢氧化镁等)，在此基础上进行单面或者双面的纯胶或者胶和陶瓷粒子混合涂布(该胶可以是单一种PVDF或者多种PVDF混合的产物)，涂布的方式可以使用水系涂布、油系涂布。
水系隔膜是指：将单一品种或者多种PVDF在水中分散、研磨形成悬浊液过滤进行涂布得到的成品，涂布的方式可以是微凹版辊转移涂布或者喷涂。油系隔膜是指：将单一品种或者多种PVDF以一定的比例(m：n，m、n可以取0～10的数)溶解在有机溶剂(例如NMP、DMAC/丙酮等)进行涂布得到的成品，涂布的方式可以是微凹版辊转移涂布或者直接浸涂。
在不同加工方式下，隔膜的表面静电值不一样，如水系隔膜静电值<300V，单面陶瓷双面油系产品的静电值约为1000V，而双面陶瓷与胶的混涂隔膜静电高达3000V以上或者更大。这样的隔膜在用于制备锂离子电池过程中往往带有较大的静电，可以吸附空气中的微小颗粒，使得锂离子电池的电芯内部处于微短路状态(如电芯的电压降非常明显，最大值可以达到0.1mV/h或者更大)。
发明内容
本公开通过在隔膜中引入添加剂，该添加剂在隔膜表面形成具有低静电功能的结构，降低隔膜的静电数值，能够在不降低隔膜与电极片的粘接性的前提下，具有低静电、高制程能力，如电池的良率较高，不良项抽芯、Hi-Pot不良占比能够处于较低水平。
本公开提供如下技术方案：
一种隔膜，所述隔膜包括隔膜涂层；所述隔膜涂层中含有第一添加剂和第二添加剂，所述第一添加剂与所述第二添加剂的质量比(g:g)为1:9～9:1；所述隔膜涂层包括若干胶层孔，所述胶层孔的孔径为0.01μm～10μm。
在一实例中，所述第一添加剂与所述第二添加剂的质量比(g:g)为2:8～8:2。
在一实例中，所述胶层孔中，孔径在1μm～3μm范围内的胶层孔占胶层孔总数的30％～70％。
在一实例中，所述第二添加剂为有机物微球，所述有机物微球满足下述至少一个条件：
1)所述有机物微球中的有机物的重均分子量为5×10 5Da～30×10 5Da；
2)所述有机物微球的平均粒径D50为0.1μm～300μm；
3)所述有机物微球中的有机物的熔点为100℃～200℃；
4)所述有机物微球中的有机物选自含氟聚合物或丙烯酸酯类聚合物中的至少一种；
5)所述有机物微球部分溶解或者极少部分溶解到有机溶剂里面，从而形成网眼结构；
6)所述有机物微球中的有机物选自聚偏氟乙烯(PVDF)、聚四氟乙烯(PTFE)或聚甲基丙烯酸甲酯(PMMA)中的至少一种。
在一实例中，所述第一添加剂以长链网格状连接在所述第二添加剂表面。
在一实例中，所述第一添加剂选自PVDF，其熔点为150℃～160℃，重均分子量为3×10 5Da～7×10 5Da。
在一实例中，所述隔膜包括基材隔膜和位于所述基材隔膜的至少一个表面上的所述隔膜涂层，所述隔膜涂层的厚度为0.1μm～3μm。
在一实例中，当所述隔膜涂层设置在所述基材隔膜的两个表面上时，所述隔膜包括2个所述隔膜涂层，2个所述隔膜涂层的总厚度为0.2μm～5μm。
在一实例中，所述基材隔膜的厚度为1μm～30μm。
在一实例中，所述基材隔膜选自PE和/或PP组成的单层基材隔膜或多层基材隔膜。
在一实例中，所述隔膜为油系隔膜。
在一实例中，所述隔膜的静电值均值小于1500V。
在一实例中，所述隔膜的自放电均值小于0.045mV/h。
本公开还提供一种锂离子电池，所述锂离子电池包括上述的隔膜。
有益效果：
本公开在隔膜表面引入第二添加剂有机物，使得有机物在溶剂体系中与第一添加剂发生部分交联现象，同时大部分的第二添加剂有机物还保存着原有的完整形态，能够与第一添加剂形成球联现象，该小球能够在不同的球体表面进行连接，从而形成多层蜂状结构，能够形成多且大的巨型网眼结构，使得油系隔膜或者油系混涂隔膜的静电值明显降低，例如从3000V或者更高降到低于1200V以内。本公开通过降低油系/油系混涂的隔膜表面的静电吸附能力，能够减少吸附微小颗粒，降低电芯的自放电值，从而提高电芯质量。
本公开通过在隔膜表面引入第二添加剂的有机物微球与第一添加剂形成网眼结构，本公开的隔膜可用于替代目前在隔膜涂层中引入的陶瓷颗粒，从而达到降低隔膜表面涂层的表面能、降低隔膜表面的静电的目的。
附图简要说明
图1为本公开的有机物在涂层中的示意图；其中，黑色球代表第一添加剂有机物；线条代表隔膜表面涂层的第二添加剂；
图2为实施例1的隔膜表面的SEM图；
图3为实施例2的隔膜表面的SEM图；
图4为实施例3的隔膜表面的SEM图；
图5为实施例4的隔膜表面的SEM图；
图6为对比例1的隔膜表面的SEM图；
图7为卷芯抽芯的示意图；其中1-卷芯；2-极耳；3-隔膜。
具体实施方式
如前所述，本公开提供了一种隔膜涂层，所述隔膜涂层中含有第一添加剂和第二添加剂；所述隔膜涂层包括若干胶层孔，所述胶层孔的孔径为0.01μm～10μm。
根据本公开的实施方案，所述第一添加剂和所述第二添加剂在所述隔膜涂层中形成多角度互联的网眼结构，所述网眼结构包括所述若干胶层孔。具体的，如图2或图3所示。
根据本公开的实施方案，所述胶层孔中，孔径在1μm～3μm范围内的胶层孔的数量占胶层孔总数的30％～70％。选择这样的孔径，特别是这样的孔径分布，原因在于这样的孔径分布能够形成层状与多孔分布，能够增加油系隔膜的比表面积，从而降低隔膜在涂布、分切、使用过程的静电产生，利于隔膜使用；例如，当胶层孔径<1μm占比高(比如占比达40％以上)时，隔膜静电值明显偏高(>2000V)，不利于生产。另外，若全部是所述孔径时，胶层与极片粘接力变弱，所以选择30％～70％的范围。
根据本公开的实施方案，所述第二添加剂为有机物微球，所述有机物微球中的有机物的重均分子量为5×10 5Da～30×10 5Da，示例性地，可以为5×10 5Da、6×10 5Da、7×10 5Da、8×10 5Da、8.5×10 5Da、9×10 5Da、10×10 5Da、11×10 5Da、12×10 5Da、13×10 5Da、14×10 5Da、15×10 5Da、20×10 5Da、30×10 5Da。具体地，所述有机物微球中的有机物的重均分子量为8×10 5Da～10×10 5Da或10×10 5Da～30×10 5Da。发明人发现，有机物微球中有机物的分子量越大，极性越大，分子链越长，其在有机溶剂溶解需要的时间越长，越有利于形成上述网眼结构，而且该结构的层状结构越明显，防静电效果越明显。
根据本公开的实施方案，所述有机物微球的平均粒径D50为0.1μm～300μm，例如可以为0.1μm、0.3μm、1μm、2μm、3μm、3.5μm、3.724μm、4μm、5μm、10μm、50μm、100μm、200μm或300μm。示例性地，所述有机物微球的平均粒径D50为0.3μm～10μm，具体地为0.3μm～5μm。选择如此粒径分布的微球，目的在于所述有机物微球的平均粒径D50越小，形成上述网眼结构越均匀，且平均粒径D50越小越 有利于涂布控制。
根据本公开的实施方案，所述有机物微球中的有机物的熔点为100℃～200℃，具体地，熔点可以为100℃、110℃、120℃、130℃、140℃、145℃、150℃、155℃、160℃、170℃、180℃、190℃或200℃；示例性地，熔点为140℃～155℃。当有机物的熔点过低时，有机物的玻璃化温度偏低，不利于隔膜应用；当有机物的熔点过高时，有机物的结晶度过高，不利于形成网眼结构。
根据本公开的实施方案，所述有机物微球中的有机物选自含氟聚合物或丙烯酸酯类聚合物中的至少一种，所述有机物微球部分溶解或者极少部分溶解到有机溶剂(如NMP或者DMAC)里面，从而成为构成上述网眼结构的基础，进一步通过第一添加剂的互联形成上述网眼结构。
根据本公开的实施方案，所述有机物微球中的有机物选自聚偏氟乙烯(PVDF)、聚四氟乙烯(PTFE)或聚甲基丙烯酸甲酯(PMMA)中的至少一种。
示例性地，所述有机物微球中的有机物选自PVDF，其具有上述有机物的性能、如重均分子量和熔点。
根据本公开的实施方案，所述第一添加剂选自有机物，该有机物包括第二添加剂的有机物微球中的有机物；所述第一添加剂以长链网格状连接在所述第二添加剂(如有机物微球)表面，从而形成所述网眼结构。
示例性地，所述第一添加剂选自PVDF，其熔点为150℃～160℃，重均分子量为3×10 5Da～7×10 5Da。
根据本公开的实施方案，所述第一添加剂与所述第二添加剂的质量比(g:g)为1:9～9:1，具体地，可以根据两者的溶解度或者分子量进行搭配，例如为1:9、2:8、3:7、4:6、5:5、6:4、7:3、8:2或9:1。通过调节所述第一添加剂与所述第二添加剂的质量比，得到上述网眼结构。若仅加入第二添加剂，不利于形成上述网眼结构。
根据本公开的实施方案，所述第一添加剂与所述第二添加剂的质量比(g:g)为2:8～8:2。
本公开还提供一种隔膜，所述隔膜包括上述的隔膜涂层。
根据本公开的实施方案，所述隔膜包括基材隔膜和设置在所述基材隔膜的至少一个表面上的上述的隔膜涂层。
根据本公开的实施方案，所述隔膜涂层设置在所述基材隔膜的一个表面上时，所述隔膜包括1个所述隔膜涂层，1个所述隔膜涂层的厚度为0.1μm～3μm，例如为0.8μm～1.2μm。
根据本公开的实施方案，所述隔膜涂层设置在所述基材隔膜的两个表面上时，所述隔膜包括2个所述隔膜涂层，2个所述隔膜涂层的总厚度为0.2μm～5μm，例如为1.8μm～2.2μm。
根据本公开的实施方案，所述基材隔膜选自PE和/或PP组成的单层基材隔膜或多层基材隔膜。示例性地，所述基材隔膜选自PP/PE/PP的三层基材隔膜。
根据本公开的实施方案，所述第二添加剂在所述隔膜涂层中形成稳定的骨架支撑(如图1所示)，能够将隔膜表面的隔膜涂层凸现出来，从而在所述隔膜涂层表面形成胶层孔，所述胶层孔通过第一添加剂的互联形成所述网眼结构，具体如图2或图3所示。
根据本公开的实施方案，所述基材隔膜的厚度为1μm～30μm。
根据本公开的实施方案，所述隔膜为油系隔膜。
根据本公开的实施方案，所述隔膜的静电值均值小于1500V。发明人发现，当隔膜的静电值均值小于1500V时，隔膜吸附空气中微小颗粒能力下降，能够降低隔膜吸附微小颗粒，进而降低异物引入电芯本体的几率。
根据本公开的实施方案，所述隔膜的自放电均值小于0.045mV/h。发明人发现，如此的自放电值的隔膜，在应用于电芯时，单只电芯的长期存放性能好，多只电芯的串压差小，电芯失效比例降低。
根据本公开的实施方案，所述隔膜在使用过程中不易吸引轻小物体，可以减少异物进入电芯本体的几率。
本公开还提供一种锂离子电池，所述锂离子电池包括上述隔膜。
根据本公开的实施方案，所述锂离子电池还包括正极。
根据本公开的实施方案，所述正极至少包括正极集流体、正极涂层和极耳。
根据本公开的实施方案，所述正极集流体选自铝箔，所述铝箔的厚度为8μm～14μm。
根据本公开的实施方案，所述正极涂层包括正极活性物质、正极导电剂和正极粘结剂。
根据本公开的实施方案，所述正极活性物质选自LiCoO 2、LiNiO 2、LiFePO 4、LiMn 2O 4或LiNi xCo yMn 1-x-yO 2中的至少一种。
根据本公开的实施方案，所述正极导电剂选自导电炭黑、碳纳米管、导电石墨或石墨烯中的至少一种。
根据本公开的实施方案，所述正极粘结剂选自聚偏二氟乙烯、偏氟乙烯-氟化烯烃的共聚物、聚四氟乙烯、羧甲基纤维素钠、丁苯橡胶、聚氨酯、氟化橡胶或聚乙烯醇中的至少一种。
根据本公开的实施方案，所述正极涂层中，所述正极活性物质的质量分数为96％～98.5％，所述正极导电剂的质量分数为0.5％～2.5％，所述正极粘结剂的质量分数为1％～1.5％。
根据本公开的实施方案，所述锂离子电池还包括负极。
根据本公开的实施方案，所述负极包括负极集流体、负极涂层和极耳。
根据本公开的实施方案，所述负极涂层包括负极活性物质、负极导电剂、负极粘结剂和分散剂。
根据本公开的实施方案，所述负极活性物质选自中间相碳微球、人造石墨、天然石墨、硬碳、软碳、钛酸锂、硅基材料、锡基材料或锂金属中的至少一种。
根据本公开的实施方案，所述负极导电剂选自导电炭黑、碳纳米管、导电石墨或石墨烯中的至少一种。
根据本公开的实施方案，所述负极粘结剂选自聚偏二氟乙烯、偏氟乙烯-氟化烯烃的共聚物、聚四氟乙烯、羧甲基纤维素钠、丁苯橡胶、聚氨酯、氟化橡胶、聚乙烯醇中的至少一种。
根据本公开的实施方案，所述分散剂选自羧甲基纤维素钠和/或羧甲基纤维素钾。
根据本公开的实施方案，所述负极涂层中，所述负极活性物质的质量分数为95％～97％，所述负极导电剂的质量分数为1.0％～2％，所述负极粘结剂的质量分数为1％～1.5％，所述分散剂的质量分数为0％～1.5％。
下文将结合具体实施例对本公开的技术方案做更进一步的详细说明。应当理解，下列实施例仅为示例性的说明和解释本公开，而不应被解释为对本公开保护范围的限制。凡基于本公开上述内容所实现的技术均涵盖在本公开旨在保护的范围内。
除非另有说明，以下实施例中使用的原料和试剂均为市售商品，或者可以通过已知方法制备。
本公开中的缩写如下：DMAC是指二甲基乙酰胺；DMF是指N,N-二甲基甲酰胺。
以下对比例和实施例中使用的第二添加剂是聚偏氟乙烯(PVDF)微球，其中，PVDF的熔点为145±5℃，重均分子量在8×10 5Da～10×10 5Da之间，微球的平均粒径D50为3.724μm。第一添加剂是常规PVDF，其熔点为150℃～160℃，重均分子量在3×10 5Da～7×10 5Da之间。
本公开中的静电值是通过基恩士SK-H050测试得到。将各组隔膜的静电值计算得平均值即为静电值均值。
实施例1
制备油性隔膜
选择上述第二添加剂PVDF微球进行按量添加10％进行涂布生产，隔膜基材为PE，厚度为5μm；涂布浆料的固体含量在7.5％，溶剂为DMAC；其中PVDF占比37.5％，其中第二添加剂PVDF按照PVDF的总量的10％加入涂布浆料中进行搅拌，搅拌时长30min，浆料粘度控制在130～180mPa·s，涂布为双面涂布，2个涂层的总厚度为2μm，涂布后得到油性隔膜1。
将上述油性隔膜2进行测试，测得表面静电值并记录在表1。
实施例2
制备油性隔膜
本实施例的隔膜的制备方法同实施例1，不同在于，第二添加剂PVDF微球占PVDF总质量的30％，得到油性隔离膜2。测得其表面静电值并记录在表1。
实施例3
制备油性隔膜
本实施例的隔膜的制备方法同实施例1，不同在于，第二添加剂PVDF微球占PVDF总质量的50％，得到油性隔离膜3。测得其表面静电值并记录在表1。
实施例4
制备油性隔膜
本实施例的隔膜的制备方法同实施例1，不同在于，第二添加剂PVDF微球占PVDF总质量的70％，得到油性隔离膜4。测得其表面静电值并记录在表1。
对比例1
涂布浆料中，固体含量在7.5％，溶剂为DMAC；其中，第一添加剂选用常规PVDF，其占固体总质量的37.5％，溶液的粘度在130～180mPa·s。
将涂布浆料在5μm厚的PE基材隔膜表面涂布，涂布厚度为双面涂布，2个涂层的总厚度为2μm，涂布后得到油性隔膜5。
将上述油性隔膜5进行测试，表面静电值记录在表1。
测试例1
如图2-图5所示为实施例1-4的隔膜表面的SEM图，从SEM图中可以看出隔膜表面形成如图2-图5的网眼结构，有机物在涂层间起到骨架与连接，该有机物能够在有机溶剂(中)进行部分溶胀或者高温和长时间浸泡溶解，当发生部分溶解时，该有机物能够在球的周围进行衔接到溶剂中已经溶解的PVDF成分，形成独特的形貌(例如图1所示的骨架支撑结构)，该形貌具有多空和特定的骨架结构。从图2-图5的隔膜表面的SEM图中观察并记录隔膜涂层的孔径分布情况于表1中，其中， 孔径指形成表面孔的直径，当孔为椭圆形时按照长轴方向计算。
如图6所示为对比例1的隔膜表面的SEM图，从SEM图中可以看出隔膜表面无网眼结构，其隔膜表面的孔径分布情况记录于表1中。
测试例2
1、软包电池制备：
隔膜：分别选用上述对比例1和实施例1-4制备得到的隔膜1-5；
正极结构：箔材选用铝箔，10μm；正极涂层包括：正极活性物质为LiCoO 2，占比97.80％；正极导电剂为导电炭黑，占比1.10％；正极粘结剂为聚偏二氟乙烯，占比1.10％；
负极结构：箔材选用铜箔，5μm；负极涂层包括：负极活性物质为中间相碳微球，占比96.50％，负极导电剂为碳纳米管，占比0.90％，负极粘结剂为SBR，占比1.30％，分散剂为羧甲基纤维素钠/CMC，占比1.30％；
电解液：EC:EMC:DEC＝3:5:2(质量比)，LiPF 6为1.2mol/L；
将上述隔膜1-5分别与上述正极和负极组装成软包电池，记为电池1-5。
2、电芯自放电测试方法：将上述实施例1-4和对比例1的电池1-5分别取32PCS进行一次化成激活或者容量筛选后在45℃下进行老化48h，然后取出常温静置24h后测试电芯电压V1时间记为t1，然后隔48h后进行第二次电压测试记为V2，时间记为t2，则电芯自放电大小K值(单位mV/h)为：
K＝(V1-V2)/(t2-t1)；将各组电池的K值计算得平均值即为自放电均值，记录与表1中。
3、抽芯检测：
将上述实施例1-4和对比例1的隔膜分组在电芯卷绕过程生产使用，每组跟进3000pcs生产量，抽芯现象是指，在卷绕过程中最内圈的隔膜与卷针直接接触，当卷针抽出时，隔膜与卷针之间的静电吸附或动摩擦力较大会导致隔膜被拉出于卷芯之外，造成卷芯抽芯，如图7为卷芯抽芯的示意图，其中，a表示隔膜露出于卷芯之外的部分的长度，即a表示卷芯的抽芯距离，单位为毫米。当0≤a≤0.5mm时， 认为点芯质量合格；当a＞0.5mm时，认为卷芯质量不合格。记录不合格卷芯数量，并根据下述公式计算不良率：抽芯不良率＝不合格卷芯数量/3000，计算结果记录于表1。
4、Hi-Pot测试：
将上述实施例1-4和对比例1的电池1-5分别取3000PCS分组后用于本测试，在绝缘电阻测试仪(型号：HIOKI ST5520)上进行Hi-Pot测试，测试条件为：电压100V，时间2.5s，面压：0.2Mpa，当阻值>2MΩ时记为合格，当阻值＜2MΩ时记为不合格。Hi-Pot不良率＝各组不合格电池数量/3000，计算结果记录于表1。
表1测试结果
Figure PCTCN2022129949-appb-000001
根据表1的测试结果可知，对比例1的油性隔膜的静电值很大，易吸附轻小粉尘或者颗粒，造成电芯内部自放电变大。而实施例1-4的油性隔膜的静电值低于1200V，其膜面的静电值较小与水系隔膜接近。由此可以看出，第二添加剂有机物微球后，在隔膜的涂层中形成独特的交联效果，从而得到本公开的隔膜胶层的 胶层孔，具体为：所述胶层孔的孔径为0.01μm～10μm；所述胶层孔中，孔径在1μm～3μm的胶层孔占胶层孔总数的30％～70％。因此，本公开的隔膜胶层可以有效地降低隔膜涂层的静电值，降低隔膜表面吸附轻小物体/颗粒的能力，达到降低电芯自放电的效果，随着第二添加剂有机物微球含量增加，形成的网眼结构明显且降低表面静电值明显，将实施例1-4的隔膜用于电芯后，电芯的自放电均值有所降低。
本方法可以通过添加一定量的第二添加剂有机物进行改变凹版油系隔膜的表面形貌降低表面静电值，同时增加隔膜的可制造性。
本公开通过在隔膜表面引入第二添加剂的有机物微球与第一添加剂形成网眼结构，可用于替代目前在隔膜胶层中引入的陶瓷颗粒。
以上对本公开示例性的实施方式进行了说明。但是，本公开的保护范围不拘囿于上述实施方式。本领域技术人员在本公开的精神和原则之内，所做的任何修改、等同替换、改进等，均应包含在本公开的保护范围之内。

Claims (15)

  1. 一种隔膜，其特征在于，所述隔膜包括隔膜涂层；所述隔膜涂层中含有第一添加剂和第二添加剂，所述第一添加剂与所述第二添加剂的质量比(g:g)为1:9～9:1；所述隔膜涂层包括若干胶层孔，所述胶层孔的孔径为0.01μm～10μm。
  2. 根据权利要求1所述的隔膜，其特征在于，所述第一添加剂与所述第二添加剂的质量比(g:g)为2:8～8:2。
  3. 根据权利要求1或2所述的隔膜，其特征在于，所述胶层孔中，孔径为1□m～3□m的胶层孔占胶层孔总数的30％～70％。
  4. 根据权利要求1-3任一项所述的隔膜，其特征在于，所述第二添加剂为有机物微球，所述有机物微球满足下述至少一个条件：
    1)所述有机物微球中的有机物的重均分子量为5×10 5Da～30×10 5Da；
    2)所述有机物微球的平均粒径D50为0.1μm～300μm；
    3)所述有机物微球中的有机物的熔点为100℃～200℃；
    4)所述有机物微球中的有机物选自含氟聚合物或丙烯酸酯类聚合物中的至少一种；
    5)所述有机物微球部分溶解或者极少部分溶解到有机溶剂里面，从而形成网眼结构；
    6)所述有机物微球中的有机物选自聚偏氟乙烯、聚四氟乙烯或聚甲基丙烯酸甲酯中的至少一种。
  5. 根据权利要求1-3任一项所述的隔膜，其特征在于，所述有机物微球满足下述至少一个条件：
    1)所述有机物微球中的有机物的重均分子量为8×10 5Da～10×10 5Da；
    2)所述有机物微球的平均粒径D50为0.3μm～10μm；
    3)所述有机物微球中的有机物的熔点为140℃～155℃；
    4)所述有机物微球中的有机物选自聚偏氟乙烯；
    5)所述有机物微球部分溶解或者极少部分溶解到有机溶剂里面，从而形成网眼结构。
  6. 根据权利要求1-5任一项所述的隔膜，其特征在于，所述第一添加剂以长链网格状连接在所述第二添加剂表面；
    和/或，所述第一添加剂选自PVDF，其熔点为150℃～160℃，重均分子量 为3×10 5Da～7×10 5Da。
  7. 根据权利要求1-6任一项所述的隔膜，其特征在于，所述隔膜包括基材隔膜和位于所述基材隔膜的至少一个表面上的所述隔膜涂层。
  8. 根据权利要求7所述的隔膜，其特征在于，当所述隔膜涂层设置在所述基材隔膜的一个表面上时，所述隔膜包括1个隔膜涂层，1个所述隔膜涂层的厚度为0.1μm～3μm；
    当所述隔膜涂层设置在所述基材隔膜的两个表面上时，所述隔膜包括2个隔膜涂层，2个隔膜涂层的总厚度为0.2μm～5μm。
  9. 根据权利要求7或8所述的隔膜，其特征在于，所述基材隔膜的厚度为1μm～30μm；和/或，
    所述基材隔膜选自PE和/或PP组成的单层基材隔膜或多层基材隔膜；
    优选地，所述基材隔膜选自PP/PE/PP的三层基材隔膜。
  10. 根据权利要求1-9任一项所述的隔膜，其特征在于，所述隔膜为油系隔膜；
    优选地，所述隔膜的静电值均值小于1500V；
    优选地，所述隔膜的自放电均值小于0.045mV/h。
  11. 一种锂离子电池，其特征在于，所述锂离子电池包括权利要求1-10任一项所述的隔膜。
  12. 根据权利要求11所述的锂离子电池，其特征在于，所述锂离子电池还包括正极，所述正极至少包括正极集流体、正极涂层和极耳；
    优选地，所述正极集流体的厚度为8μm～14μm。
  13. 根据权利要求12所述的锂离子电池，其特征在于，所述正极涂层包括正极活性物质、正极导电剂和正极粘结剂；
    优选地，所述正极涂层中，所述正极活性物质的质量分数为96％～98.5％，所述正极导电剂的质量分数为0.5％～2.5％，所述正极粘结剂的质量分数为1％～1.5％。
  14. 根据权利要求11-13任一项所述的锂离子电池，其特征在于，所述锂离子电池还包括负极，所述负极包括负极集流体、负极涂层和极耳。
  15. 根据权利要求14所述的锂离子电池，其特征在于，所述负极涂层包括负极活性物质、负极导电剂、负极粘结剂和分散剂；
    优选地，所述负极涂层中，所述负极活性物质的质量分数为95％～97％，所述负极导电剂的质量分数为1.0％～2％，所述负极粘结剂的质量分数为1％～1.5％，所述分散剂的质量分数为0％～1.5％。
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