WO2024007964A1 - Composite separator and preparation method therefor, secondary battery and electric device - Google Patents

Composite separator and preparation method therefor, secondary battery and electric device Download PDF

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Publication number
WO2024007964A1
WO2024007964A1 PCT/CN2023/104146 CN2023104146W WO2024007964A1 WO 2024007964 A1 WO2024007964 A1 WO 2024007964A1 CN 2023104146 W CN2023104146 W CN 2023104146W WO 2024007964 A1 WO2024007964 A1 WO 2024007964A1
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WIPO (PCT)
Prior art keywords
heat
composite separator
inorganic particles
separator
impedance
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PCT/CN2023/104146
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French (fr)
Chinese (zh)
Inventor
孙泽蒙
阳东方
谢封超
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华为技术有限公司
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Publication of WO2024007964A1 publication Critical patent/WO2024007964A1/en

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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
    • 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
    • H01M10/054—Accumulators with insertion or intercalation of metals other than lithium, e.g. with magnesium or aluminium
    • 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
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • 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
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte
    • 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
    • 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
    • H01M50/446—Composite material consisting of a mixture of organic and inorganic materials
    • 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
    • H01M50/451—Separators, membranes or diaphragms characterised by the material having a layered structure comprising layers of only organic material and layers containing inorganic material
    • 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
    • H01M50/489—Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
    • 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

  • This application relates to the field of batteries, specifically to a composite separator and its preparation method, secondary batteries and electrical equipment.
  • separator as one of the main materials of lithium-ion batteries, plays an important role in battery safety.
  • the most commonly used separator at present is polyethylene separator.
  • the thermal shrinkage rate of this separator is usually MD>10%; TD>10% (150°C/1h); and the membrane rupture temperature of this separator is usually ⁇ 160°C. Therefore, when the temperature of the battery rises, the separator melts due to heat and shrinks severely, which will cause the positive and negative electrodes of the battery to come into direct contact, easily inducing a short circuit inside the battery and causing the battery to undergo thermal runaway.
  • the surface of the separator is usually coated with a coating, such as an organic heat-resistant polymer coating or a ceramic coating, to improve the thermal stability of the separator.
  • a coating such as an organic heat-resistant polymer coating or a ceramic coating
  • pore-forming agents or particles are generally added.
  • pore-forming agents generally refer to the Inorganic or organic substances that will decompose to produce gas will cause porous voids in the organic heat-resistant polymer coating.
  • This application provides a composite separator and its preparation method, secondary batteries and electrical equipment. While ensuring that the separator has high thermal stability, it also solves the problem of rising separator impedance caused by the heat-resistant coating to reduce the impedance of the separator. .
  • the application provides a composite separator.
  • the composite separator includes a base film and a heat-resistant coating bonded to at least one side surface of the base film.
  • the heat-resistant coating includes heat-resistant resin and inorganic particles.
  • the heat-resistant resin and inorganic particles The mass ratio of the particles is ⁇ 6:4, the inorganic particles have a porous structure, the specific surface area of the inorganic particles is 50-150m 2 /g, and the impedance of the composite separator is ⁇ 1 ⁇ /cm 2 .
  • the heat-resistant resin in the heat-resistant coating of the composite separator of this application can increase the heat-resistant temperature of the composite separator.
  • the separator can withstand high temperatures without melting, and can effectively isolate the positive electrode of the battery. and negative electrode to avoid short circuit caused by direct contact between the positive and negative electrodes and improve the safety of the battery.
  • the inorganic particles in the heat-resistant coating can increase the thermal stability of the composite separator, effectively reduce shrinkage during thermal abuse (shrinkage ⁇ 5%, 150°C 1h), reduce the probability of battery short circuit, and reduce battery life. Thermal runaway probability in thermal runaway scenarios.
  • the inorganic particles in this application have a porous structure, and their specific surface area is in the range of 50 to 150 m 2 /g.
  • the inorganic particles with this specific surface area can have more through-pore structures and improve the penetrability of active ions.
  • the heat-resistant resin includes aramid.
  • aramid as heat-resistant resin, the membrane rupture temperature of the composite separator can be increased to 300°C and above, further improving the heat resistance of the composite separator.
  • the membrane rupture temperature of the composite separator can be ⁇ 300°C.
  • the specific surface area of the inorganic particles is 60 to 150 m 2 /g, preferably 60 to 140 m 2 /g, and further preferably 60 to 110 m 2 /g.
  • the mass ratio of heat-resistant resin to inorganic particles is ⁇ 3:7.
  • the mass ratio of heat-resistant resin and inorganic particles can be controlled at 1:9 or above.
  • this application provides a method for preparing a composite separator.
  • the preparation method includes: a base film coated with a heat-resistant coating slurry. After drying and heat fixing, a composite separator is obtained; wherein the drying temperature is 50-120°C and the drying time is ⁇ 10 min; the heat fixing temperature is 60-150°C and the heat fixing time is ⁇ 5 min.
  • the preparation method provided by this application can fully evaporate the solvent in the heat-resistant coating slurry by controlling the temperature and time during the drying process without affecting the distance between molecules in the heat-resistant resin, making the heat-resistant resin Appropriate molecular spacing is maintained between molecules to facilitate the passage of active ions, thereby enabling the composite separator to obtain a lower impedance.
  • the molecules in the heat-resistant coating can be regularly arranged to achieve the final shape of the composite separator, and at the same time, the distance between the molecules in the heat-resistant coating can be maintained. Excessive reduction, so that it still has a suitable molecular spacing, thereby improving the heat resistance of the composite separator while avoiding an increase in the impedance of the composite separator.
  • the drying temperature is 50-100°C and the drying time is ⁇ 5 minutes.
  • the heat fixing temperature is 60-110°C, and the heat fixing time is ⁇ 2 minutes.
  • the data in each of the above possible implementation methods of this application such as the mass ratio of heat-resistant resin and inorganic particles, the specific surface area of inorganic particles, the impedance of the composite separator, the membrane rupture temperature of the composite separator, drying temperature, drying time, heat fixation
  • the values within the engineering measurement error range should be understood to be within the scope limited by this application.
  • the present application provides a secondary battery, which includes a positive electrode sheet, a negative electrode sheet, and a composite separator of the present application disposed between the positive electrode sheet and the negative electrode sheet.
  • the secondary battery of the present application includes, but is not limited to, lithium secondary battery, potassium secondary battery, sodium secondary battery, zinc secondary battery, magnesium secondary battery or aluminum secondary battery.
  • the composite separator of the present application has good heat resistance and low impedance, the secondary battery of the present application can have the advantages of high safety and fast charging.
  • the present application provides an electrical device, which includes the secondary battery of the present application.
  • the electrical equipment in this application includes but is not limited to mobile terminal devices, such as computers, mobile phones, tablets, wearable products, new energy vehicles, and other mobile equipment.
  • mobile terminal devices such as computers, mobile phones, tablets, wearable products, new energy vehicles, and other mobile equipment.
  • the technical effects that can be achieved by this electrical equipment can be described with reference to the corresponding effects in the third aspect above, and will not be repeated here.
  • Figure 1 is a schematic structural diagram of a composite separator provided by an embodiment of the present application.
  • the separator For secondary batteries, such as lithium-ion batteries, the separator, one of the main materials, plays an important role in battery safety.
  • the separator is subject to mechanical abuse or thermal abuse, the separator is prone to thermal shrinkage or rupture, which can easily lead to battery short circuit and cause thermal runaway of the battery.
  • a heat-resistant coating is formed by coating the surface of the porous base membrane with a heat-resistant polymer to reduce the thermal shrinkage of the separator and increase the rupture temperature of the separator, thereby increasing the heat resistance of the battery and reducing the risk of mechanical abuse or abuse of the battery.
  • thermal abuse such as high temperature
  • the thermal shrinkage and thermal rupture of the diaphragm may lead to the risk of short circuit and safety accidents.
  • heat-resistant polymers are prone to shrinking at high temperatures.
  • Inorganic particles can be added to the heat-resistant coating to reduce the shrinkage rate of the separator and improve the puncture strength of the separator to ensure the safety of the separator when the battery is used.
  • the separator containing the heat-resistant coating with the above structure will have a problem of increased impedance compared to the base film, making it infeasible to be used in high-performance battery scenarios such as fast charging.
  • FIG. 1 is a schematic structural diagram of a composite separator according to an embodiment of the present application.
  • the composite separator 11 includes a base film 12 and a film bonded to at least one side surface of the base film 12.
  • Heat-resistant coating 13 includes heat-resistant resin and inorganic particles.
  • the mass ratio of heat-resistant resin to inorganic particles is ⁇ 6:4.
  • the inorganic particles have a porous structure and the specific surface area of the inorganic particles is 50 to 150 m 2 / g, the impedance of the composite diaphragm is ⁇ 1 ⁇ /cm 2 .
  • the heat-resistant coating 13 can be provided on one side surface of the base film 12 or on both sides of the base film 12 .
  • the material of the base film 12 includes, but is not limited to, polyethylene, polypropylene, poly1-butene, poly1-pentene, poly1-hexene, poly4-methyl-1-pentene, poly1- - One or a combination of at least two of octene, polyvinyl acetate, polymethylmethacrylate, polystyrene, polyvinylidene fluoride, polytetrafluoroethylene, polymethylmethacrylate.
  • the heat-resistant resin includes but is not limited to polyamide, polysulfone, polyimide, polyamide-imide, polyethersulfone, polyvinylidene fluoride, polyvinylidene fluoride, Vinyl difluoride-hexafluoropropylene copolymer, polystyrene, polyacrylate or its modifications, polyester, polyarylate, polyacrylonitrile, aromatic polyamide, polyimide, polyethersulfone, polysulfone , one or a combination of at least two of polyetherketone, polyetherimide, polybenzimidazole or their copolymers.
  • the heat-resistant resin is preferably polyamide, and further preferably is aromatic polyamides including aramid.
  • aromatic polyamide as the heat-resistant resin can effectively increase the membrane rupture temperature of the composite separator.
  • the inorganic particles are inorganic particles with a porous structure.
  • the porous structure of the inorganic particles can improve the ability of the composite separator to retain the electrolyte, store metal ions in the electrolyte in the porous structure of the inorganic particles, and can be used to reduce the overall impedance of the composite separator.
  • the porous structure inorganic particles mentioned in the embodiments of the present application are inorganic particles containing a porous structure or having a porous structure shape.
  • Porous structural structures include but are not limited to direct observation of inorganic particles through SEM, TEM and other means to obtain their porous structure.
  • Porous structural properties include, but are not limited to, inorganic particles obtained in the following ways: by testing inorganic particles with a specific surface area of not less than 50m 2 /g; by testing inorganic particles with a porosity greater than 1% through liquid immersion weighing method, density method, etc. Inorganic particles whose relative density (relative to the density of non-porous materials) is less than 99%; the average pore diameter of the inorganic particles is not less than 0.005 microns, as measured by mercury porosimetry.
  • the inorganic particles are selected from porous particles with a specific surface area of 50 to 150 m 2 /g. Choosing inorganic particles with this specific surface area can ensure the thermal stability of the composite separator while solving the problem of rising impedance of the composite separator caused by the heat-resistant coating. In this way, the impedance of the composite separator can be better reduced while effectively ensuring the heat resistance of the composite separator, thereby achieving battery safety while meeting the performance of fast charging.
  • the specific surface area of the inorganic particles can be, for example, 50m 2 /g, 60m 2 /g, 70m 2 /g, 80m 2 /g, 90m 2 /g, 100m 2 /g, 110m 2 /g, 120m 2 /g, 130m 2 /g, 140m 2 /g, or 150m 2 /g.
  • the pores of the porous-structured inorganic particles are through-pores, they will directly serve as transmission channels for metal ions during the charging and discharging process of the battery, further reducing the impedance of the composite separator.
  • Porous particles with a specific surface area of 60 to 150 m 2 /g can not only improve the heat resistance of the composite separator, but also increase the transmission channels for metal ions during the charge and discharge process.
  • the more transmission channels for active ions the smaller the impedance of the composite separator. .
  • the impedance of the composite separator is ⁇ 0.9 ⁇ /cm 2 .
  • the average particle size of the inorganic particles is not specifically limited, and particles with an average particle size ⁇ 2 ⁇ m may be preferred. It can be understood that in the embodiments of the present application, there are no restrictions on the shape, size, and whether the holes of the inorganic particles are through holes.
  • the inorganic particles in the embodiments of the present application include, but are not limited to, metal oxides, metal nitrides, metal hydroxides, metal carbonates, metal carbonates, metal sulfates, boehmite, and apatite.
  • metal oxides metal oxides, metal nitrides, metal hydroxides, metal carbonates, metal carbonates, metal sulfates, boehmite, and apatite.
  • the metal oxide may be, for example, at least one of aluminum oxide, titanium dioxide, silicon dioxide, zirconium dioxide or magnesium oxide.
  • the metal nitride may include at least one of aluminum nitride and titanium nitride, for example.
  • the metal hydroxide may include, for example, at least one of aluminum hydroxide and magnesium hydroxide.
  • the metal carbonate may include, for example, at least one of aluminum carbonate, magnesium carbonate, and calcium carbonate.
  • the metal carbonate may include, for example, at least one of aluminum phosphate, magnesium phosphate, and calcium phosphate.
  • the metal sulfate may include, for example, at least one of aluminum sulfate, magnesium sulfate, barium sulfate, and the like.
  • the mass ratio of the heat-resistant resin and the inorganic particles in the heat-resistant coating satisfies ⁇ 6:4, and preferably the ratio of the two satisfies ⁇ 3:7.
  • the composite separator can achieve a high membrane rupture temperature and at the same time, the composite separator can have lower impedance.
  • the mass ratio of the heat-resistant resin to the inorganic particles may be, for example, 6:4, 5:5, 4:6, 3:7, 2:8, or 1:9.
  • composition of the composite separator has been explained above, and the preparation method of the composite separator will be further explained below.
  • the preparation method of the composite separator in the embodiment of the present application may include the following steps: drying and heat-fixing the base film coated with the heat-resistant coating slurry in sequence to obtain a composite separator.
  • the drying temperature is 50-120°C, preferably 50-100°C, and the drying time is ⁇ 10 min, preferably ⁇ 5 min.
  • the heat fixing temperature is 60-150°C, preferably 60-110°C, and the heat fixation time is ⁇ 5 min, preferably ⁇ 2 min.
  • the drying process can be carried out in a drying box, and the number of drying boxes can be 1, 2, or more.
  • the same or different temperatures can be set in each drying box.
  • the temperature in each drying box should comply with the temperature range defined in the embodiments of this application.
  • the heat fixing process can be carried out in a heat fixing box.
  • the number of heat fixing boxes can be 1, 2 or more.
  • the same heat fixing box can be set in each heat fixing box.
  • different temperatures wherein the temperature in each heat fixing box should comply with the temperature range defined in the embodiment of this application.
  • the heat-resistant resin in the heat-resistant coating will undergo a heat fixation effect, and the molecules in the heat-resistant coating will be regularly arranged to improve the mechanical strength and heat-resistant performance of the heat-resistant coating.
  • the molecules are arranged more regularly, which can easily lead to a reduction in the distance between molecules, thereby increasing the resistance of the separator.
  • the molecules of the heat-resistant coating can be maintained in an appropriate position on the basis of achieving a regular arrangement of molecules. spacing, thereby improving the mechanical strength and heat resistance of the composite separator while effectively ensuring that the impedance of the obtained composite separator is ⁇ 1 ⁇ /cm 2 .
  • the preparation method of heat-resistant coating slurry includes the following steps: place 100 parts by weight of heat-resistant resin and 50 to 5000 parts by weight of inorganic particles in a reactor, and then add an organic solvent to fully disperse , to obtain heat-resistant coating slurry.
  • the solid content in the obtained heat-resistant coating slurry is preferably 5%-50%; the solid content refers to the mass percentage of solid parts such as heat-resistant resin and inorganic particles in the heat-resistant coating slurry.
  • organic solvents include but are not limited to N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, acetone and ethanol.
  • N-methylpyrrolidone N,N-dimethylformamide
  • N,N-dimethylacetamide N,N-dimethylacetamide
  • acetone ethanol
  • co-solvents when preparing the heat-resistant coating slurry, co-solvents, dispersants, emulsifiers, polymer binders, etc. can be added as needed.
  • the co-solvent, dispersant, polymer binder, etc. can be selected from commercially available products.
  • the co-solvent can be one or more of sodium benzoate, lithium chloride, calcium chloride, sodium hydroxide, and acetamide.
  • the dispersant can be one or more combinations of polyethylene oxide, ethylene-acrylic acid copolymer, ethylene-vinyl acetate copolymer
  • the emulsifier can be cetyltrimethylammonium chloride, octadecyl Trimethylammonium chloride, sodium polyacrylate, potassium polyacrylate, polyacrylamide, dodecyltrimethylammonium chloride, ethylene oxide-butylene oxide copolymer, ethylene oxide-propylene oxide - One or more combinations of butylene oxide copolymers
  • the polymer binder can be one or more combinations of polyvinylpyrrolidone, vinylpyrrolidone, and ethylene acetate copolymers.
  • the specific preparation process of the composite separator may include the following steps:
  • Step S11 Prepare a uniform heat-resistant coating slurry, which can be mixed using stirring, ultrasonic treatment, etc. to obtain a heat-resistant coating slurry with uniform composition;
  • Step S12 apply heat-resistant coating slurry on one or both sides of the base film
  • Step S13 The base film coated with the heat-resistant coating slurry is first washed with water to remove the oil solvent, and then dried, heat-fixed, and rolled up in order to obtain a review separator with a heat-resistant coating in the plane direction.
  • This embodiment is a composite separator, and its preparation process includes the following steps:
  • Step S11 Select 5.0 ⁇ m polyethylene film as the base material, with an air permeability of 140s.
  • the drying oven temperature is 100°C and the drying time is 2 minutes; the heat fixing oven temperature is 110°C and the heat fixing time is 1 minute.
  • the drying box and the heat fixing box are arranged continuously and separately.
  • the thickness of the heat-resistant coating was 2 ⁇ m.
  • the indicators of the composite diaphragm are listed in Table 1.
  • This embodiment is a composite separator.
  • the difference compared with Embodiment 1 is that in the composite separator in this embodiment, both sides of the base film are coated with heat-resistant coatings. Others are the same as Example 1.
  • the indicators of the composite diaphragm are listed in Table 1.
  • This embodiment is a composite separator.
  • the difference from Example 1 is that the weight ratio of the heat-resistant resin to the inorganic particles in the heat-resistant coating of this example is different. Others are the same as Example 1.
  • the indicators of the composite diaphragm are listed in Table 1.
  • Examples 4 to 6 are respectively a composite separator. The difference from Example 1 is that the specific surface area of the inorganic particles used in Examples 4 to 6 is different. Others are the same as Example 1. The indicators of the composite separators of Examples 4 to 6 are listed in Table 1.
  • Embodiment 7 is a composite separator.
  • the difference compared with Embodiment 1 is that the drying process and heat fixing process used in Embodiment 7 are different, and the others are the same as Embodiment 1.
  • the drying temperature is 60°C
  • the drying time is 2 minutes
  • the heat fixing temperature is 80°C
  • the heat fixing time is 1 minute.
  • This comparative example is a composite separator.
  • the difference compared with Example 1 is that in the composite separator in this comparative example, the inorganic particles in the heat-resistant coating are inorganic particles with a non-porous structure.
  • the specific specific surface area values are listed in Table 1 .
  • Others are the same as Example 1.
  • the indicators of the composite diaphragm are listed in Table 2.
  • Comparative Examples 2 to 3 are respectively a composite separator. Compared with Example 1, the difference lies in that the specific surface area of the inorganic particles used in Comparative Examples 2 to 3 is different. Others are the same as Example 1. The indicators of the composite separators of Comparative Examples 2 to 3 are listed in Table 2.
  • This comparative example is a composite separator.
  • the difference from Example 2 is that the drying conditions and heat fixing conditions are different.
  • the drying oven temperature in this comparative example is 125°C
  • the drying time is 15 minutes
  • the heat fixing oven temperature is 135°C.
  • Heat fixation time is 10 minutes.
  • the rest is the same as Example 2.
  • the indicators of the composite separator of Comparative Example 4 are listed in Table 2.
  • This comparative example is a composite separator.
  • the difference compared with Example 1 is that in the composite separator in this comparative example, the inorganic particles in the heat-resistant coating are inorganic particles with a non-porous structure.
  • ammonium bicarbonate pore-forming agent
  • the testing method of the specific surface area of the inorganic particles in the above embodiments and comparative examples is as follows: it is measured by the nitrogen adsorption method using the American Quanta specific surface area measuring instrument NOVA2000e.
  • the gas used is a mixture of helium and nitrogen, with nitrogen as the adsorbed gas and helium as the carrier gas.
  • the temperature inside the injector drops to a certain level, and the energy of the nitrogen molecules decreases. They are adsorbed by the solid surface under the action of van der Waals force, reach dynamic equilibrium, and form a state similar to a monomolecular layer.
  • the specific surface area value of a substance is directly proportional to its adsorption capacity.
  • the specific surface area of the tested sample can be calculated by comparing the adsorption capacity of a known specific surface substance (standard sample) with the adsorption capacity of an unknown specific surface substance.
  • Method 1 Cut the sample from the diaphragm. The number of test points depends on the condition of the diaphragm (usually no less than 10 points); test it with a ten thousandth thickness measuring instrument under the condition of 23 ⁇ 2°C; measure the actual thickness value of each test point. and take the arithmetic mean.
  • Test Test each test point with a thickness measuring instrument at 23 ⁇ 2°C.
  • the diameter of the measuring surface should be between 2.5mm and 10mm, and the load applied to the sample on the measuring surface should be between 0.5N and 1.0 between N.
  • Sampling randomly cut 6 samples from the full width.
  • the specific sampling of each sample can include: cut 100mm along the MD direction of the diaphragm; when the TD direction of the diaphragm is greater than 100mm, test the sample in the TD direction.
  • the length can be 100mm; when the TD direction of the microporous membrane is less than 100mm, the length of the test sample in the TD direction can be subject to actual conditions.
  • Test Mark the longitudinal and transverse markings of the sample, measure and record the longitudinal and transverse dimensions of each sample; place the sample flat in the paper jacket layer, and make sure there is no folding, wrinkling, adhesion, etc. of the sample;
  • the paper sleeve with the sample sandwiched therein (the number of layers can be, for example, 10) is placed flatly into the middle of the constant temperature oven (the door opening time is, for example, no more than 3 seconds); the sample is heated to 150°C by the electric thermostatic oven, and the heating time is 1 hour; take it out. After sample Cool to room temperature and measure the longitudinal and transverse lengths.
  • T (L 0 -L)/L 0 ⁇ 100%, where T can be the thermal shrinkage rate of the sample (%), L 0 can be the length of the sample before heating (mm), and L can be the sample after heating length (mm). Calculate the arithmetic mean of the thermal shrinkage in the MD and TD directions of the sample.
  • Test according to the method specified in standard JIS P8117-2009.
  • the cylinder drives the pressure reducing valve 0.25MPa, and the test pressure is 0.05MPa. Record the value of the measured point, test 5 times and take the average value.
  • the membrane rupture temperature of the composite separators in the embodiments of the present application can reach 300°C and above, and the impedance of the composite separators is also less than 1 ⁇ /cm 2 , and the impedance The increase rate is also less than 50%, and the impedance increase rate is basically within 30%.
  • the heat-resistant coating can have a lower impedance and have less impact on the impedance of the entire composite separator, and a low-impedance separator can be obtained.
  • Example 1 when the specific surface area of the inorganic particles is in the range of 60 to 110 m 2 /g, a composite separator with lower shrinkage rate and lower impedance can be obtained.
  • Comparative Example 2 uses porous particles with a specific surface area of 300 m 2 /g. Although the resistance of the composite separator obtained is small, the shrinkage rate is higher than that of the composite separators of various embodiments of the present application, and the membrane rupture temperature of Comparative Example 2 is low. Composite separators in various embodiments of the present application.
  • Example 2 and Comparative Example 4 it can be seen from the relevant data of Example 2 and Comparative Example 4 that by changing the drying process and heat fixing process in the preparation process of the composite separator, the impedance of the composite separator can be significantly reduced, thereby obtaining low shrinkage and high membrane rupture temperature. and low-impedance composite diaphragms.
  • the relevant test data of Example 1 and Example 7 it can be seen from the relevant test data of Example 1 and Example 7 that when the drying process and the heat fixing process are optimized, the shrinkage rate of the obtained composite separator can be further reduced.
  • the composite separator corresponding to this comparative example can no longer meet the thermal stability requirements of secondary batteries for separators.
  • the composite separator in Example 1 of the present application by selecting porous inorganic particles with a specific specific surface area, a low-impedance composite separator can be obtained without changing the air permeability of the composite separator.
  • the composite separator of the embodiment of the present application can not only meet the requirements of thermal stability but also achieve various effects of low impedance by using porous inorganic particles with a specific specific surface area.

Abstract

The present application provides a composite separator and a preparation method therefor, a secondary battery, and an electric device. The composite separator comprises a base film and a heat-resistant coating bonded to at least one side surface of the base film; the heat-resistant coating comprises heat-resistant resin and inorganic particles; a mass ratio of the heat-resistant resin to the inorganic particles is less than or equal to 6:4; the inorganic particles are of a porous structure; the specific surface area of the inorganic particles is 50-150 m2/g; and the impedance of the composite separator is less than or equal to 1 Ω/cm2. Therefore, the problem of separator impedance rise caused by the heat-resistant coating is solved while ensuring the high thermal stability of the separator, so that the impedance of the separator is reduced.

Description

复合隔膜及其制备方法、二次电池和用电设备Composite separator and preparation method thereof, secondary battery and electrical equipment
相关申请的交叉引用Cross-references to related applications
本申请要求在2022年07月06日提交中国专利局、申请号为202210798624.7、申请名称为“复合隔膜及其制备方法、二次电池和用电设备”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。This application requires the priority of the Chinese patent application submitted to the China Patent Office on July 6, 2022, with the application number 202210798624.7 and the application name "Composite separator and its preparation method, secondary battery and electrical equipment", and its entire content incorporated herein by reference.
技术领域Technical field
本申请涉及电池领域，具体涉及一种复合隔膜及其制备方法、二次电池和用电设备。This application relates to the field of batteries, specifically to a composite separator and its preparation method, secondary batteries and electrical equipment.
背景技术Background technique
随着电动汽车、智能终端和电子移动装置的发展，二次电池，例如锂离子电池也得到快速发展。隔膜，作为锂离子电池主材之一，在电池安全中扮演着重要角色。当前最常用的隔膜为聚乙烯隔膜，该隔膜的热收缩率通常为MD＞10％；TD＞10％(150℃/1h)；且该隔膜的破膜温度通常＜160℃。因此，当电池温度升高后，隔膜受热融化且收缩严重时会导致电池的正极和负极直接接触，容易诱发电池内部的短路，使电池发生热失控。为提升隔膜的热稳定性，隔膜的表面通常涂覆涂层，如有机耐热高分子涂层或陶瓷涂层，以提高隔膜的热稳定性。例如在聚乙烯隔膜上加入有机耐热高分子涂层后，为了使得隔膜产生孔隙以达到离子透过的效果，一般会采用造孔剂或加入粒子，其中，造孔剂一般是指在特定温度下会分解产生气体的无机物或有机物，从而使得有机耐热高分子涂层产生孔状空隙。该方式可提高隔膜的热稳定性，但隔膜的阻抗会上升，从而导致电池能力下降的问题。With the development of electric vehicles, smart terminals, and electronic mobile devices, secondary batteries, such as lithium-ion batteries, have also been rapidly developed. Separator, as one of the main materials of lithium-ion batteries, plays an important role in battery safety. The most commonly used separator at present is polyethylene separator. The thermal shrinkage rate of this separator is usually MD>10%; TD>10% (150°C/1h); and the membrane rupture temperature of this separator is usually <160°C. Therefore, when the temperature of the battery rises, the separator melts due to heat and shrinks severely, which will cause the positive and negative electrodes of the battery to come into direct contact, easily inducing a short circuit inside the battery and causing the battery to undergo thermal runaway. In order to improve the thermal stability of the separator, the surface of the separator is usually coated with a coating, such as an organic heat-resistant polymer coating or a ceramic coating, to improve the thermal stability of the separator. For example, after adding an organic heat-resistant polymer coating to a polyethylene separator, in order to create pores in the separator to achieve the effect of ion permeation, pore-forming agents or particles are generally added. Among them, pore-forming agents generally refer to the Inorganic or organic substances that will decompose to produce gas will cause porous voids in the organic heat-resistant polymer coating. This method can improve the thermal stability of the separator, but the impedance of the separator will increase, resulting in a decrease in battery capacity.
发明内容Contents of the invention
本申请提供了一种复合隔膜及其制备方法、二次电池和用电设备，在保证隔膜具有高热稳定性的同时，解决由耐热涂层导致的隔膜阻抗上升的问题，以降低隔膜的阻抗。This application provides a composite separator and its preparation method, secondary batteries and electrical equipment. While ensuring that the separator has high thermal stability, it also solves the problem of rising separator impedance caused by the heat-resistant coating to reduce the impedance of the separator. .
第一方面，本申请提供一种复合隔膜，该复合隔膜包括基膜和结合于基膜至少一侧表面的耐热涂层，耐热涂层包括耐热树脂和无机粒子，耐热树脂与无机粒子的质量比≤6:4，无机粒子为多孔结构，无机粒子的比表面积为50～150m2/g，复合隔膜的阻抗≤1Ω/cm2。In a first aspect, the application provides a composite separator. The composite separator includes a base film and a heat-resistant coating bonded to at least one side surface of the base film. The heat-resistant coating includes heat-resistant resin and inorganic particles. The heat-resistant resin and inorganic particles The mass ratio of the particles is ≤6:4, the inorganic particles have a porous structure, the specific surface area of the inorganic particles is 50-150m 2 /g, and the impedance of the composite separator is ≤1Ω/cm 2 .
本申请的复合隔膜，其耐热涂层中的耐热树脂可提升复合隔膜的耐热温度，在电池受到热滥用和机械滥用时，该隔膜能耐受高温不融化，能有效隔绝电池的正极和负极，避免正极和负极直接接触导致短路，提升电池的安全性。另外，耐热涂层中的无机粒子，可增加复合隔膜的热稳定性，能有效减少热滥用中的收缩(收缩率≦5％，150℃1h)，降低电池发生短路的概率，并降低电池在热失控场景中的热失控概率。本申请中的无机粒子为多孔结构，且其比表面积在50～150m2/g范围内，该比表面积的无机粒子，可具有更多的贯通孔结构，并提高活性离子的穿透性，同时，具备更好的电解液吸附性及保液性，在保证耐热性的前提下从实质上降低复合隔膜的阻抗，使复合隔膜的阻抗降低至1Ω/cm2及以下，阻抗增加率≦50％。The heat-resistant resin in the heat-resistant coating of the composite separator of this application can increase the heat-resistant temperature of the composite separator. When the battery is subjected to thermal abuse and mechanical abuse, the separator can withstand high temperatures without melting, and can effectively isolate the positive electrode of the battery. and negative electrode to avoid short circuit caused by direct contact between the positive and negative electrodes and improve the safety of the battery. In addition, the inorganic particles in the heat-resistant coating can increase the thermal stability of the composite separator, effectively reduce shrinkage during thermal abuse (shrinkage ≦5%, 150°C 1h), reduce the probability of battery short circuit, and reduce battery life. Thermal runaway probability in thermal runaway scenarios. The inorganic particles in this application have a porous structure, and their specific surface area is in the range of 50 to 150 m 2 /g. The inorganic particles with this specific surface area can have more through-pore structures and improve the penetrability of active ions. At the same time, , has better electrolyte adsorption and liquid retention properties, and substantially reduces the impedance of the composite separator while ensuring heat resistance, so that the impedance of the composite separator is reduced to 1Ω/ cm2 and below, and the impedance increase rate is ≦50 %.
在一种可能的实现方式中，耐热树脂包括芳纶。耐热树脂通过选用芳纶，可使复合隔膜的破膜温度提升至300℃及以上，以进一步提升复合隔膜的耐热性能。在一种可能的实现方式中，复合隔膜的破膜温度可≥300℃。In one possible implementation, the heat-resistant resin includes aramid. By using aramid as heat-resistant resin, the membrane rupture temperature of the composite separator can be increased to 300°C and above, further improving the heat resistance of the composite separator. In a possible implementation, the membrane rupture temperature of the composite separator can be ≥300°C.
在一种可能的实现方式中，无机粒子的比表面积为60～150m2/g，优选为60～140m2/g，进一步优选为60～110m2/g。通过优化无机粒子的比表面积，可达到在保证复合隔膜耐热性能的同时进一步降低复合隔膜的阻抗。In a possible implementation, the specific surface area of the inorganic particles is 60 to 150 m 2 /g, preferably 60 to 140 m 2 /g, and further preferably 60 to 110 m 2 /g. By optimizing the specific surface area of the inorganic particles, the impedance of the composite separator can be further reduced while ensuring the heat resistance of the composite separator.
在一种可能的实现方式中，复合隔膜的阻抗增加率≤50％，优选阻抗增加率≤20％，进一步优选阻抗增加率≤10％；其中，复合隔膜的阻抗增加率＝(复合隔膜阻抗-基膜阻抗)/基膜阻抗×100％。由此，可获得阻抗更小的复合隔膜，以降低电池的电芯内阻，提高电池的快充性能。In a possible implementation, the impedance increase rate of the composite diaphragm is ≤50%, preferably the impedance increase rate is ≤20%, and further preferably the impedance increase rate is ≤10%; wherein, the impedance increase rate of the composite diaphragm = (composite diaphragm impedance - Basement membrane resistance)/basement membrane resistance×100%. As a result, a composite separator with smaller impedance can be obtained to reduce the internal resistance of the battery cell and improve the fast charging performance of the battery.
在一种可选的实现方式中，耐热树脂与无机粒子的质量比≤3:7。示例性的，耐热树脂和无机粒子的质量比可控制在1:9及以上。通过优化耐热树脂和无机粒子的质量比，可在保证复合隔膜具有较高破膜温度的情况下获得较低的阻抗。In an optional implementation, the mass ratio of heat-resistant resin to inorganic particles is ≤3:7. For example, the mass ratio of heat-resistant resin and inorganic particles can be controlled at 1:9 or above. By optimizing the mass ratio of heat-resistant resin and inorganic particles, lower impedance can be obtained while ensuring that the composite separator has a higher membrane rupture temperature.
第二方面，本申请提供一种复合隔膜的制备方法，该制备方法包括：涂覆有耐热涂层浆料的基膜经 干燥和热固定后得到复合隔膜；其中，干燥温度为50～120℃，干燥时间≤10min；热固定温度为60～150℃，热固定时间为≤5min。In a second aspect, this application provides a method for preparing a composite separator. The preparation method includes: a base film coated with a heat-resistant coating slurry. After drying and heat fixing, a composite separator is obtained; wherein the drying temperature is 50-120°C and the drying time is ≤10 min; the heat fixing temperature is 60-150°C and the heat fixing time is ≤5 min.
本申请提供的制备方法，通过控制干燥过程中的温度和时间，可使耐热涂层浆料中的溶剂充分蒸发，且不会影响耐热树脂中的分子间的间距，使耐热树脂的分子之间保持合适的分子间距，以利于活性离子的通过，从而可使复合隔膜获得较低的阻抗。热固定阶段，通过控制热固定温度和热固定时间，可在使耐热涂层中的分子规整化排列以使复合隔膜获得定型的同时，使耐热涂层中的分子之间的间距不会过度缩小，使其仍具有合适的分子间距，进而在提高复合隔膜耐热性能的同时避免复合隔膜阻抗的增加。The preparation method provided by this application can fully evaporate the solvent in the heat-resistant coating slurry by controlling the temperature and time during the drying process without affecting the distance between molecules in the heat-resistant resin, making the heat-resistant resin Appropriate molecular spacing is maintained between molecules to facilitate the passage of active ions, thereby enabling the composite separator to obtain a lower impedance. In the heat fixation stage, by controlling the heat fixation temperature and heat fixation time, the molecules in the heat-resistant coating can be regularly arranged to achieve the final shape of the composite separator, and at the same time, the distance between the molecules in the heat-resistant coating can be maintained. Excessive reduction, so that it still has a suitable molecular spacing, thereby improving the heat resistance of the composite separator while avoiding an increase in the impedance of the composite separator.
在一种可选的实现方式中，干燥温度为50～100℃，干燥时间≤5min。在一种可选的实现方式中，热固定温度为60～110℃，热固定时间为≤2min。通过优化干燥温度和干燥时间以及热固定温度和热固定时间，可在进一步提高复合隔膜的耐热性能的同时，进一步降低复合隔膜的阻抗。In an optional implementation, the drying temperature is 50-100°C and the drying time is ≤5 minutes. In an optional implementation, the heat fixing temperature is 60-110°C, and the heat fixing time is ≤2 minutes. By optimizing the drying temperature and drying time as well as the heat fixing temperature and heat fixing time, the heat resistance of the composite separator can be further improved while the impedance of the composite separator can be further reduced.
其中，本申请上述各可能实现方式中的数据，例如耐热树脂和无机粒子的质量比、无机粒子的比表面积、复合隔膜的阻抗、复合隔膜的破膜温度、干燥温度、干燥时间、热固定温度和热固定时间等数据，在测量时，工程测量误差范围内的数值均应理解为在本申请所限定的范围内。Among them, the data in each of the above possible implementation methods of this application, such as the mass ratio of heat-resistant resin and inorganic particles, the specific surface area of inorganic particles, the impedance of the composite separator, the membrane rupture temperature of the composite separator, drying temperature, drying time, heat fixation When measuring data such as temperature and thermal fixation time, the values within the engineering measurement error range should be understood to be within the scope limited by this application.
第三方面，本申请提供一种二次电池，该二次电池包括正极片、负极片、以及设置正极片和负极片之间的如本申请的复合隔膜。In a third aspect, the present application provides a secondary battery, which includes a positive electrode sheet, a negative electrode sheet, and a composite separator of the present application disposed between the positive electrode sheet and the negative electrode sheet.
本申请的二次电池包括但不限于锂二次电池、钾二次电池、钠二次电池、锌二次电池、镁二次电池或铝二次电池。在本申请复合隔膜具备耐热性好、阻抗低的基础上，本申请的二次电池可具有安全性高以及可实现快速充电的优势。The secondary battery of the present application includes, but is not limited to, lithium secondary battery, potassium secondary battery, sodium secondary battery, zinc secondary battery, magnesium secondary battery or aluminum secondary battery. On the basis that the composite separator of the present application has good heat resistance and low impedance, the secondary battery of the present application can have the advantages of high safety and fast charging.
第四方面，本申请提供一种用电设备，该用电设备包括本申请的二次电池。In a fourth aspect, the present application provides an electrical device, which includes the secondary battery of the present application.
本申请的用电设备包括但不限于移动终端装置，如电脑、手机、平板、穿戴产品，及新能源汽车，等移动装备中。该用电设备可以达到的技术效果，可以参照上述第三方面中的相应效果描述，这里不再重复赘述。The electrical equipment in this application includes but is not limited to mobile terminal devices, such as computers, mobile phones, tablets, wearable products, new energy vehicles, and other mobile equipment. The technical effects that can be achieved by this electrical equipment can be described with reference to the corresponding effects in the third aspect above, and will not be repeated here.
附图说明Description of the drawings
图1为本申请实施例提供的一种复合隔膜的结构示意图。Figure 1 is a schematic structural diagram of a composite separator provided by an embodiment of the present application.
附图标记：11-复合隔膜；12-基膜；13-耐热涂层。Reference signs: 11-composite separator; 12-base film; 13-heat-resistant coating.
具体实施方式Detailed ways
为了使本申请的目的、技术方案和优点更加清楚，下面将结合附图对本申请作进一步地详细描述。In order to make the purpose, technical solutions and advantages of the present application clearer, the present application will be described in further detail below in conjunction with the accompanying drawings.
以下实施例中所使用的术语只是为了描述特定实施例的目的，而并非旨在作为对本申请的限制。如在本申请的说明书和所附权利要求书中所使用的那样，单数表达形式“一个”、“一种”、“所述”、“上述”、“该”和“这一”旨在也包括例如“一个或多个”这种表达形式，除非其上下文中明确地有相反指示。The terminology used in the following examples is for the purpose of describing specific embodiments only and is not intended to limit the application. As used in the specification and appended claims of this application, the singular expressions "a", "an", "said", "above", "the" and "the" are intended to also Expressions such as "one or more" are included unless the context clearly indicates otherwise.
在本说明书中描述的参考“一个实施例”或“一些实施例”等意味着在本申请的一个或多个实施例中包括结合该实施例描述的特定特征、结构或特点。由此，在本说明书中的不同之处出现的语句“在一个实施例中”、“在一些实施例中”、“在其他一些实施例中”、“在另外一些实施例中”等不是必然都参考相同的实施例，而是意味着“一个或多个但不是所有的实施例”，除非是以其他方式另外特别强调。术语“包括”、“包含”、“具有”及它们的变形都意味着“包括但不限于”，除非是以其他方式另外特别强调。Reference in this specification to "one embodiment" or "some embodiments" or the like means that a particular feature, structure or characteristic described in connection with the embodiment is included in one or more embodiments of the application. Therefore, the phrases "in one embodiment", "in some embodiments", "in other embodiments", "in other embodiments", etc. appearing in different places in this specification are not necessarily References are made to the same embodiment, but rather to "one or more but not all embodiments" unless specifically stated otherwise. The terms “including,” “includes,” “having,” and variations thereof all mean “including but not limited to,” unless otherwise specifically emphasized.
二次电池，例如锂离子电池，其主材之一的隔膜在电池安全中扮演重要的角色。隔膜在机械滥用或热滥用场景下，隔膜易发生热收缩或易破膜，易导致电池短路，从而引发电池热失控。通过在多孔基膜表面涂覆耐热高分子聚合物形成耐热涂层，以降低隔膜的热收缩性及提升隔膜的破膜温度，从而增加了电池的耐热能力，减少电池在机械滥用或者热滥用(如高温)场景下由于隔膜发生热收缩及热破膜导致短路和安全事故的风险。但耐热高分子聚合物在高温下易发生收缩，可通过在耐热涂层中加入无机粒子降低隔膜的收缩率及提高隔膜的穿刺强度，确保在电池使用时隔膜的安全性。但在提高隔膜安全性的同时，相对于基膜，含上述结构耐热涂层的隔膜会出现阻抗增大的问题，导致在快速充电等高性能电池场景无法应用。For secondary batteries, such as lithium-ion batteries, the separator, one of the main materials, plays an important role in battery safety. When the separator is subject to mechanical abuse or thermal abuse, the separator is prone to thermal shrinkage or rupture, which can easily lead to battery short circuit and cause thermal runaway of the battery. A heat-resistant coating is formed by coating the surface of the porous base membrane with a heat-resistant polymer to reduce the thermal shrinkage of the separator and increase the rupture temperature of the separator, thereby increasing the heat resistance of the battery and reducing the risk of mechanical abuse or abuse of the battery. In thermal abuse (such as high temperature) scenarios, the thermal shrinkage and thermal rupture of the diaphragm may lead to the risk of short circuit and safety accidents. However, heat-resistant polymers are prone to shrinking at high temperatures. Inorganic particles can be added to the heat-resistant coating to reduce the shrinkage rate of the separator and improve the puncture strength of the separator to ensure the safety of the separator when the battery is used. However, while improving the safety of the separator, the separator containing the heat-resistant coating with the above structure will have a problem of increased impedance compared to the base film, making it infeasible to be used in high-performance battery scenarios such as fast charging.
为解决上述技术问题，本申请实施例提供一种复合隔膜。图1为本申请一种实施例的复合隔膜的结构示意图，如图1所示，在一种实施例中，复合隔膜11包括基膜12和结合于基膜12至少一侧表面的 耐热涂层13，耐热涂层13包括耐热树脂和无机粒子，耐热树脂与无机粒子的质量比≤6:4，无机粒子为多孔结构，无机粒子的比表面积为50～150m2/g，复合隔膜的阻抗≤1Ω/cm2。可以理解的是，耐热涂层13可设于基膜12的一侧表面，也可设于基膜12的两侧表面。In order to solve the above technical problems, embodiments of the present application provide a composite separator. Figure 1 is a schematic structural diagram of a composite separator according to an embodiment of the present application. As shown in Figure 1, in one embodiment, the composite separator 11 includes a base film 12 and a film bonded to at least one side surface of the base film 12. Heat-resistant coating 13. The heat-resistant coating 13 includes heat-resistant resin and inorganic particles. The mass ratio of heat-resistant resin to inorganic particles is ≤6:4. The inorganic particles have a porous structure and the specific surface area of the inorganic particles is 50 to 150 m 2 / g, the impedance of the composite diaphragm is ≤1Ω/cm 2 . It can be understood that the heat-resistant coating 13 can be provided on one side surface of the base film 12 or on both sides of the base film 12 .
参照图1，基膜12的材料包括但不限于聚乙烯、聚丙烯、聚1-丁烯、聚1-戊烯、聚1-己烯、聚4-甲基-1-戊烯、聚1-辛烯、聚乙酸乙烯酯、聚甲基丙烯酸甲酯、聚苯乙烯、聚偏二氟乙烯、聚四氟乙烯、聚甲基丙烯酸甲酯中的一种或至少两种的组合。Referring to FIG. 1 , the material of the base film 12 includes, but is not limited to, polyethylene, polypropylene, poly1-butene, poly1-pentene, poly1-hexene, poly4-methyl-1-pentene, poly1- - One or a combination of at least two of octene, polyvinyl acetate, polymethylmethacrylate, polystyrene, polyvinylidene fluoride, polytetrafluoroethylene, polymethylmethacrylate.
参照图1，本申请实施例的耐热涂层13中，耐热树脂包括但不限于聚酰胺、聚砜、聚酰亚胺、聚酰胺酰亚胺、聚醚砜、聚偏氟乙烯、偏二氟乙烯-六氟丙烯共聚物、聚苯乙烯、聚丙烯酸酯或其改性物、聚酯、聚芳酯、聚丙烯腈、芳香族聚酰胺、聚酰亚胺、聚醚砜、聚砜、聚醚酮、聚醚酰亚胺、聚苯并咪唑或其共聚物中的一种或至少两种的组合。在本申请一种优选实施例中，耐热树脂优选为聚酰胺，进一步优选为包括芳纶的芳香族聚酰胺类。其中，选用芳香族聚酰胺作为耐热树脂可有效提高复合隔膜的破膜温度。Referring to Figure 1, in the heat-resistant coating 13 of the embodiment of the present application, the heat-resistant resin includes but is not limited to polyamide, polysulfone, polyimide, polyamide-imide, polyethersulfone, polyvinylidene fluoride, polyvinylidene fluoride, Vinyl difluoride-hexafluoropropylene copolymer, polystyrene, polyacrylate or its modifications, polyester, polyarylate, polyacrylonitrile, aromatic polyamide, polyimide, polyethersulfone, polysulfone , one or a combination of at least two of polyetherketone, polyetherimide, polybenzimidazole or their copolymers. In a preferred embodiment of the present application, the heat-resistant resin is preferably polyamide, and further preferably is aromatic polyamides including aramid. Among them, the use of aromatic polyamide as the heat-resistant resin can effectively increase the membrane rupture temperature of the composite separator.
继续参照图1，本申请实施例的耐热涂层13中，无机粒子为多孔结构的无机粒子。无机粒子的多孔结构可以提高复合隔膜对电解液的保液能力，可将电解液中的金属离子储存在无机粒子的多孔结构中，可用于降低复合隔膜的整体阻抗。其中，本申请实施例中所提及的多孔结构的无机粒子为含有多孔结构构造或具有多孔结构形状的无机粒子。多孔结构构造包括但不限于可直接通过SEM、TEM等手段直接观察无机粒子，获得其具有孔状结构。多孔结构性质包括但不限于以下方式获得的无机粒子：通过测试比表面积不小于50m2/g的无机粒子；通过液体浸泡称重法、密度法等测试出无机粒子的开孔率大于1％、相对密度(相对于无孔材料的密度)小于99％的无机粒子；通过压汞法等测试出无机粒子的平均气孔径不小于0.005微米。Continuing to refer to FIG. 1 , in the heat-resistant coating 13 of the embodiment of the present application, the inorganic particles are inorganic particles with a porous structure. The porous structure of the inorganic particles can improve the ability of the composite separator to retain the electrolyte, store metal ions in the electrolyte in the porous structure of the inorganic particles, and can be used to reduce the overall impedance of the composite separator. Among them, the porous structure inorganic particles mentioned in the embodiments of the present application are inorganic particles containing a porous structure or having a porous structure shape. Porous structural structures include but are not limited to direct observation of inorganic particles through SEM, TEM and other means to obtain their porous structure. Porous structural properties include, but are not limited to, inorganic particles obtained in the following ways: by testing inorganic particles with a specific surface area of not less than 50m 2 /g; by testing inorganic particles with a porosity greater than 1% through liquid immersion weighing method, density method, etc. Inorganic particles whose relative density (relative to the density of non-porous materials) is less than 99%; the average pore diameter of the inorganic particles is not less than 0.005 microns, as measured by mercury porosimetry.
其中，无机粒子选自比表面积50～150m2/g的多孔粒子，选用该比表面积的无机粒子，可在保证复合隔膜的热稳定性的同时，解决由耐热涂层导致的复合隔膜阻抗上升的问题，以此，可在有效保证复合隔膜耐热性能的同时更好地降低复合隔膜的阻抗，进而实现电池安全性的同时，满足可以快速充电的性能。作为示例性说明，无机粒子的比表面积例如可为50m2/g、60m2/g、70m2/g、80m2/g、90m2/g、100m2/g、110m2/g、120m2/g、130m2/g、140m2/g、或150m2/g。Among them, the inorganic particles are selected from porous particles with a specific surface area of 50 to 150 m 2 /g. Choosing inorganic particles with this specific surface area can ensure the thermal stability of the composite separator while solving the problem of rising impedance of the composite separator caused by the heat-resistant coating. In this way, the impedance of the composite separator can be better reduced while effectively ensuring the heat resistance of the composite separator, thereby achieving battery safety while meeting the performance of fast charging. As an example, the specific surface area of the inorganic particles can be, for example, 50m 2 /g, 60m 2 /g, 70m 2 /g, 80m 2 /g, 90m 2 /g, 100m 2 /g, 110m 2 /g, 120m 2 /g, 130m 2 /g, 140m 2 /g, or 150m 2 /g.
在耐热涂层中，若多孔结构的无机粒子的孔为贯通孔，在电池的充放电过程中，则直接作为了金属离子的传输通道，可进一步降低复合隔膜的阻抗。而无机离子的比表面积越大，形成贯通孔的可能性就越高，降低复合隔膜阻抗的性能就越好，因此，本申请的复合隔膜中，无机粒子更优选比表面积≥60m2/g的多孔粒子。比表面积满足60～150m2/g的多孔粒子，在提高复合隔膜耐热性能的同时，还可增加充放电过程中金属离子的传输通道，活性离子的传输通道越多，复合隔膜的阻抗越小。在本申请一种可选的实施例中，复合隔膜的阻抗≤0.9Ω/cm2。In the heat-resistant coating, if the pores of the porous-structured inorganic particles are through-pores, they will directly serve as transmission channels for metal ions during the charging and discharging process of the battery, further reducing the impedance of the composite separator. The greater the specific surface area of inorganic ions, the higher the possibility of forming through holes, and the better the performance of reducing the impedance of the composite separator. Therefore, in the composite separator of the present application, inorganic particles with a specific surface area ≥ 60 m 2 /g are more preferred. porous particles. Porous particles with a specific surface area of 60 to 150 m 2 /g can not only improve the heat resistance of the composite separator, but also increase the transmission channels for metal ions during the charge and discharge process. The more transmission channels for active ions, the smaller the impedance of the composite separator. . In an optional embodiment of the present application, the impedance of the composite separator is ≤0.9Ω/cm 2 .
本申请实施例中，对无机粒子的平均粒径不做具体限定，可优选平均粒径≦2μm的粒子。可以理解的是，本申请实施例中并未对无机粒子的孔的形状、大小以及是否为贯通孔等不做限制。In the embodiments of the present application, the average particle size of the inorganic particles is not specifically limited, and particles with an average particle size ≦2 μm may be preferred. It can be understood that in the embodiments of the present application, there are no restrictions on the shape, size, and whether the holes of the inorganic particles are through holes.
作为示例性说明，本申请实施例的无机粒子包括但不限于金属氧合物、金属氮化物、金属氢氧化物、金属碳酸盐、金属碳酸盐、金属硫酸盐、勃母石、磷灰石、氮化硼、碳化硅、氮化硅、立方氮化硼、六方氮化硼、石墨以及石墨烯等中的一种或至少两种的组合。其中，金属氧合物例如可为三氧化二铝、二氧化钛、二氧化硅、二氧化锆或氧化镁中的至少一种。金属氮化物例如可包括氮化铝以及氮化钛中的至少一种。金属氢氧化物例如可包括氢氧化铝和氢氧化镁中的至少一种。金属碳酸盐例如可包括碳酸铝、碳酸镁、和碳酸钙中的至少一种。金属碳酸盐例如可包括磷酸铝、磷酸镁、磷酸钙中的至少一种。金属硫酸盐例如可包括硫酸铝、硫酸镁和硫酸钡等中的至少一种。As an illustration, the inorganic particles in the embodiments of the present application include, but are not limited to, metal oxides, metal nitrides, metal hydroxides, metal carbonates, metal carbonates, metal sulfates, boehmite, and apatite. One or a combination of at least two of stone, boron nitride, silicon carbide, silicon nitride, cubic boron nitride, hexagonal boron nitride, graphite and graphene. The metal oxide may be, for example, at least one of aluminum oxide, titanium dioxide, silicon dioxide, zirconium dioxide or magnesium oxide. The metal nitride may include at least one of aluminum nitride and titanium nitride, for example. The metal hydroxide may include, for example, at least one of aluminum hydroxide and magnesium hydroxide. The metal carbonate may include, for example, at least one of aluminum carbonate, magnesium carbonate, and calcium carbonate. The metal carbonate may include, for example, at least one of aluminum phosphate, magnesium phosphate, and calcium phosphate. The metal sulfate may include, for example, at least one of aluminum sulfate, magnesium sulfate, barium sulfate, and the like.
本申请实施例的复合隔膜中，耐热涂层中的耐热树脂与无机粒子的质量比满足≦6：4，优选两者比例满足≦3:7。当耐热树脂和无机粒子的质量比满足上述范围时，可使复合隔膜实现高破膜温度的同时，使复合隔膜具有更低的阻抗。其中，作为示例性说明，耐热树脂与无机粒子的质量比例如可为6:4、5:5、4:6、3:7、2:8、或1:9等。In the composite separator of the embodiment of the present application, the mass ratio of the heat-resistant resin and the inorganic particles in the heat-resistant coating satisfies ≦6:4, and preferably the ratio of the two satisfies ≦3:7. When the mass ratio of heat-resistant resin and inorganic particles meets the above range, the composite separator can achieve a high membrane rupture temperature and at the same time, the composite separator can have lower impedance. As an example, the mass ratio of the heat-resistant resin to the inorganic particles may be, for example, 6:4, 5:5, 4:6, 3:7, 2:8, or 1:9.
以上对复合隔膜的组成做了解释说明，以下将对复合隔膜的制备方法做进一步解释说明。The composition of the composite separator has been explained above, and the preparation method of the composite separator will be further explained below.
本申请实施例的复合隔膜的制备方法可包括如下步骤：使涂覆有耐热涂层浆料的基膜依次经干燥和热固定后得到复合隔膜。其中，干燥温度为50～120℃，优选为50～100℃，干燥时间≤10min，优选≤5min。热固定温度为60～150℃，优选为60～110℃，热固定时间为≤5min，优选为≤2min。 The preparation method of the composite separator in the embodiment of the present application may include the following steps: drying and heat-fixing the base film coated with the heat-resistant coating slurry in sequence to obtain a composite separator. Among them, the drying temperature is 50-120°C, preferably 50-100°C, and the drying time is ≤10 min, preferably ≤5 min. The heat fixing temperature is 60-150°C, preferably 60-110°C, and the heat fixation time is ≤5 min, preferably ≤2 min.
其中，干燥过程可在干燥箱内进行，干燥箱的数量为1个也可为2个还可为更多个，设置多个干燥箱时，每个干燥箱内可设置相同或不同的温度，其中，每个干燥箱内的温度均应符合本申请实施例限定的温度范围。同样，热固定过程可在热固定箱内进行，热固定箱的数量为1个也可为2个还可为更多个，设置多个热固定箱时，每个热固定箱内可设置相同或不同的温度，其中，每个热固定箱内的温度均应符合本申请实施例限定的温度范围。Among them, the drying process can be carried out in a drying box, and the number of drying boxes can be 1, 2, or more. When multiple drying boxes are set up, the same or different temperatures can be set in each drying box. The temperature in each drying box should comply with the temperature range defined in the embodiments of this application. Similarly, the heat fixing process can be carried out in a heat fixing box. The number of heat fixing boxes can be 1, 2 or more. When multiple heat fixing boxes are set up, the same heat fixing box can be set in each heat fixing box. Or different temperatures, wherein the temperature in each heat fixing box should comply with the temperature range defined in the embodiment of this application.
在干燥和热固定过程中，耐热涂层中耐热树脂会发生热固定效应，耐热涂层中的分子会发生规整化的排列，以提高耐热涂层的机械强度和耐热性能，但在该过程中分子的排列更规整，容易导致分子间间距减小，从而增大隔膜阻抗。而本申请通过控制复合隔膜制备过程中干燥温度和干燥时间，并控制热固定温度和热固定时间，可在实现分子规整化排布的基础上，使耐热涂层的分子之间保持合适的间距，从而在提高复合隔膜的机械强度和耐热性能的同时，可有效保证获得的复合隔膜的阻抗≦1Ω/cm2。During the drying and heat fixing process, the heat-resistant resin in the heat-resistant coating will undergo a heat fixation effect, and the molecules in the heat-resistant coating will be regularly arranged to improve the mechanical strength and heat-resistant performance of the heat-resistant coating. However, during this process, the molecules are arranged more regularly, which can easily lead to a reduction in the distance between molecules, thereby increasing the resistance of the separator. In this application, by controlling the drying temperature and drying time during the preparation process of the composite separator, and controlling the heat fixation temperature and heat fixation time, the molecules of the heat-resistant coating can be maintained in an appropriate position on the basis of achieving a regular arrangement of molecules. spacing, thereby improving the mechanical strength and heat resistance of the composite separator while effectively ensuring that the impedance of the obtained composite separator is ≦1Ω/cm 2 .
作为一种示例性说明，耐热涂层浆料的制备方法包括如下步骤：将100重量份耐热树脂，50重量份到5000重量份的无机粒子放置于反应器中，再加入有机溶剂充分分散，获得耐热涂层浆料。其中，获得的那耐热涂层浆料中，固含量优选5％-50％；固含量是指耐热涂层浆料中耐热树脂和无机粒子等固体部分的质量百分比。As an exemplary explanation, the preparation method of heat-resistant coating slurry includes the following steps: place 100 parts by weight of heat-resistant resin and 50 to 5000 parts by weight of inorganic particles in a reactor, and then add an organic solvent to fully disperse , to obtain heat-resistant coating slurry. Among them, the solid content in the obtained heat-resistant coating slurry is preferably 5%-50%; the solid content refers to the mass percentage of solid parts such as heat-resistant resin and inorganic particles in the heat-resistant coating slurry.
其中，在制备耐热涂层浆料的过程中，有机溶剂包括但不限于N-甲基吡咯烷酮、N,N-二甲基甲酰胺、N,N-二甲基乙酰胺、丙酮和乙醇中的一种或者多种组成。Among them, in the process of preparing the heat-resistant coating slurry, organic solvents include but are not limited to N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, acetone and ethanol. One or more components.
需要说明的是，在制备耐热涂层浆料时，可根据需要加入助溶剂、分散剂、乳化剂、聚合物粘结剂等。其中，助溶剂、分散剂、聚合物粘结剂等可选择市售产品，例如，助溶剂可为苯甲酸钠、氯化锂、氯化钙、氢氧化钠、乙酰胺中的一种或者多种组合；分散剂可为聚氧化乙烯、乙烯－丙烯酸共聚物、乙烯－醋酸乙烯共聚物中的一种或者多种组合；乳化剂可为十六烷基三甲基氯化铵、十八烷基三甲基氯化铵、聚丙烯酸钠、聚丙烯酸钾、聚丙烯酰胺、十二烷基三甲基氯化铵、环氧乙烷-环氧丁烷共聚物、环氧乙烷-环氧丙烷-环氧丁烷共聚物中的一种或者多种组合；聚合物粘结剂可为聚乙烯吡咯烷酮、乙烯基吡络烷酮、乙烯乙酸酯共聚物中的一种或者多种组合。It should be noted that when preparing the heat-resistant coating slurry, co-solvents, dispersants, emulsifiers, polymer binders, etc. can be added as needed. Among them, the co-solvent, dispersant, polymer binder, etc. can be selected from commercially available products. For example, the co-solvent can be one or more of sodium benzoate, lithium chloride, calcium chloride, sodium hydroxide, and acetamide. combination; the dispersant can be one or more combinations of polyethylene oxide, ethylene-acrylic acid copolymer, ethylene-vinyl acetate copolymer; the emulsifier can be cetyltrimethylammonium chloride, octadecyl Trimethylammonium chloride, sodium polyacrylate, potassium polyacrylate, polyacrylamide, dodecyltrimethylammonium chloride, ethylene oxide-butylene oxide copolymer, ethylene oxide-propylene oxide - One or more combinations of butylene oxide copolymers; the polymer binder can be one or more combinations of polyvinylpyrrolidone, vinylpyrrolidone, and ethylene acetate copolymers.
在本申请一种可选的实施例中，复合隔膜的具体制备过程可包括如下步骤：In an optional embodiment of the present application, the specific preparation process of the composite separator may include the following steps:
步骤S11、制备均匀耐热涂层浆料，可使用搅拌、超声波处理等方式进行混合以获得成分均匀的耐热涂层浆料；Step S11: Prepare a uniform heat-resistant coating slurry, which can be mixed using stirring, ultrasonic treatment, etc. to obtain a heat-resistant coating slurry with uniform composition;
步骤S12、在基膜的一面或两面涂覆耐热涂层浆料；Step S12, apply heat-resistant coating slurry on one or both sides of the base film;
步骤S13、涂覆有耐热涂层浆料的基膜先经水洗，去除油系溶剂；再依次经干燥、热固定、收卷，得到在平面方向上具备耐热涂层的复核隔膜。Step S13: The base film coated with the heat-resistant coating slurry is first washed with water to remove the oil solvent, and then dried, heat-fixed, and rolled up in order to obtain a review separator with a heat-resistant coating in the plane direction.
以下将结合具体实施例和对比例对本申请的复合隔膜的性能做进一步详细说明。The performance of the composite separator of the present application will be further described in detail below with reference to specific examples and comparative examples.
实施例1Example 1
该实施例为一种复合隔膜，其制备过程包括如下步骤：This embodiment is a composite separator, and its preparation process includes the following steps:
步骤S11、基材选用5.0μm聚乙烯薄膜，透气度为140s。Step S11: Select 5.0 μm polyethylene film as the base material, with an air permeability of 140s.
步骤S12、耐热涂层浆料的制备Step S12. Preparation of heat-resistant coating slurry
将100重量份的平均分子量为100000的间位芳纶、400重量份的比表面积为74m2/g多孔氧化铝粒子，加入4500重量份的二甲基乙酰胺溶剂(dimethylacetamide，DMAC)中，通过高速搅拌得到均匀的耐热涂层浆料。Add 100 parts by weight of meta-aramid fiber with an average molecular weight of 100,000 and 400 parts by weight of porous alumina particles with a specific surface area of 74 m 2 /g into 4500 parts by weight of dimethylacetamide solvent (dimethylacetamide, DMAC). Stir at high speed to obtain a uniform heat-resistant coating slurry.
步骤S13、复合隔膜的制备Step S13, preparation of composite separator
在聚乙烯薄膜的单面通过金属棒涂上述耐热涂层浆料后，过水，去除油系溶剂；之后进入干燥箱干燥，干燥后进入热固定箱进行热固定后得到复合隔膜成品。其中，干燥箱温度为100℃，干燥时间为2分钟；热固定箱度为110℃，热固定时间为1分钟。干燥箱和热固定箱连续且分开设置。After applying the above-mentioned heat-resistant coating slurry on one side of the polyethylene film through a metal rod, it is passed through water to remove the oil solvent; then it is dried in a drying oven, and after drying, it is placed in a heat-fixing box for heat-fixing to obtain a finished composite separator. Among them, the drying oven temperature is 100°C and the drying time is 2 minutes; the heat fixing oven temperature is 110°C and the heat fixing time is 1 minute. The drying box and the heat fixing box are arranged continuously and separately.
所得复合隔膜中，耐热涂层的厚度为2μm。该复合隔膜的指标列于如表1中。In the obtained composite separator, the thickness of the heat-resistant coating was 2 μm. The indicators of the composite diaphragm are listed in Table 1.
实施例2Example 2
该实施例为一种复合隔膜，与实施例1相比区别在于，该实施例中的复合隔膜，基膜的两侧均涂覆有耐热涂层。其他与实施例1相同。该复合隔膜的指标列于如表1中。This embodiment is a composite separator. The difference compared with Embodiment 1 is that in the composite separator in this embodiment, both sides of the base film are coated with heat-resistant coatings. Others are the same as Example 1. The indicators of the composite diaphragm are listed in Table 1.
实施例3Example 3
该实施例为一种复合隔膜，与实施例1相比区别在于，该实施例的耐热涂层中的耐热树脂与无机粒子的重量比不同，其他与实施例1相同。该复合隔膜的指标列于如表1中。 This embodiment is a composite separator. The difference from Example 1 is that the weight ratio of the heat-resistant resin to the inorganic particles in the heat-resistant coating of this example is different. Others are the same as Example 1. The indicators of the composite diaphragm are listed in Table 1.
实施例4～6Examples 4 to 6
实施例4～6分别为一种复合隔膜，与实施例1相比区别在于，实施例4～6中所用的无机粒子的比表面积不同，其他与实施例1相同。实施例4～6的复合隔膜的指标列于如表1中。Examples 4 to 6 are respectively a composite separator. The difference from Example 1 is that the specific surface area of the inorganic particles used in Examples 4 to 6 is different. Others are the same as Example 1. The indicators of the composite separators of Examples 4 to 6 are listed in Table 1.
实施例7Example 7
实施例7为一种复合隔膜，与实施例1相比区别在于，实施例7中所用的干燥工艺与热固定工艺不同，其他与实施例1相同。本实施例中，干燥温度为60℃，干燥时间为2min，热固定温度为80℃，热固定时间为1min。Embodiment 7 is a composite separator. The difference compared with Embodiment 1 is that the drying process and heat fixing process used in Embodiment 7 are different, and the others are the same as Embodiment 1. In this embodiment, the drying temperature is 60°C, the drying time is 2 minutes, the heat fixing temperature is 80°C, and the heat fixing time is 1 minute.
对比例1Comparative example 1
该对比例为一种复合隔膜，与实施例1相比区别在于，该对比例中的复合隔膜，耐热涂层中的无机粒子为无孔结构的无机粒子，具体比表面积数值列于表1。其他与实施例1相同。该复合隔膜的指标列于如表2中。This comparative example is a composite separator. The difference compared with Example 1 is that in the composite separator in this comparative example, the inorganic particles in the heat-resistant coating are inorganic particles with a non-porous structure. The specific specific surface area values are listed in Table 1 . Others are the same as Example 1. The indicators of the composite diaphragm are listed in Table 2.
对比例2～3Comparative Examples 2~3
对比例2～3分别为一种复合隔膜，与实施例1相比区别在于，对比例2～3中所用的无机粒子的比表面积不同，其他与实施例1相同。对比例2～3的复合隔膜的指标列于如表2中。Comparative Examples 2 to 3 are respectively a composite separator. Compared with Example 1, the difference lies in that the specific surface area of the inorganic particles used in Comparative Examples 2 to 3 is different. Others are the same as Example 1. The indicators of the composite separators of Comparative Examples 2 to 3 are listed in Table 2.
对比例4Comparative example 4
该对比例为一种复合隔膜，与实施例2不同的是干燥条件及热固定条件不同，该对比例中的干燥箱温度为125℃，干燥时间为15分钟；热固定箱度为135℃，热固定时间为10分钟。其余的与实施例2相同。对比例4的复合隔膜的指标列于如表2中。This comparative example is a composite separator. The difference from Example 2 is that the drying conditions and heat fixing conditions are different. The drying oven temperature in this comparative example is 125°C, the drying time is 15 minutes, and the heat fixing oven temperature is 135°C. Heat fixation time is 10 minutes. The rest is the same as Example 2. The indicators of the composite separator of Comparative Example 4 are listed in Table 2.
对比例5Comparative example 5
该对比例为一种复合隔膜，与实施例1相比区别在于，该对比例中的复合隔膜，耐热涂层中的无机粒子为无孔结构的无机粒子，在该复合隔膜的制备过程中，在耐热涂层浆料中添加质量占比为1％的碳酸氢铵(造孔剂)，干燥工艺以及热固定工艺与本申请实施例1相同。This comparative example is a composite separator. The difference compared with Example 1 is that in the composite separator in this comparative example, the inorganic particles in the heat-resistant coating are inorganic particles with a non-porous structure. In the preparation process of the composite separator , add 1% ammonium bicarbonate (pore-forming agent) by mass to the heat-resistant coating slurry, and the drying process and heat fixing process are the same as Example 1 of this application.
其中，以上各实施例和对比例中的无机粒子的比表面积的测试方法如下：采用美国康塔比表面积测定仪NOVA2000e通过氮吸附法测试得到。采用的气体是氦氮混合气，氮气为被吸附气体，氦气为载气。当样品进样器进行液氮浴时，进样器内温度降低至一定程度，氮分子能量降低，在范德华力作用下被固体表面吸附，达到动态平衡，形成近似于单分子层的状态。由于物质的比表面积数值和它的吸附量是成正比的。通过一个已知比表面物质(标准样品)的吸附量，和未知比表面物质的吸附量做对比即可算出被测样品的比表面积。Among them, the testing method of the specific surface area of the inorganic particles in the above embodiments and comparative examples is as follows: it is measured by the nitrogen adsorption method using the American Quanta specific surface area measuring instrument NOVA2000e. The gas used is a mixture of helium and nitrogen, with nitrogen as the adsorbed gas and helium as the carrier gas. When the sample injector is placed in a liquid nitrogen bath, the temperature inside the injector drops to a certain level, and the energy of the nitrogen molecules decreases. They are adsorbed by the solid surface under the action of van der Waals force, reach dynamic equilibrium, and form a state similar to a monomolecular layer. Because the specific surface area value of a substance is directly proportional to its adsorption capacity. The specific surface area of the tested sample can be calculated by comparing the adsorption capacity of a known specific surface substance (standard sample) with the adsorption capacity of an unknown specific surface substance.
分别测试各实施例和对比例中的复合隔膜的膜厚、收缩率、破膜温度、透气度、基膜阻抗、隔膜阻抗等各项性能参数，测试结果列于表1和表2。各性能参数的具体测试方法如下：Various performance parameters such as film thickness, shrinkage, membrane rupture temperature, air permeability, base film impedance, and separator impedance of the composite separators in each embodiment and comparative example were tested respectively. The test results are listed in Table 1 and Table 2. The specific test methods for each performance parameter are as follows:
1)膜厚测量1) Film thickness measurement
方式一：从隔膜上截取样品，测试点数视隔膜情况而定(通常不小于10个点)；在23±2℃条件下通过万分厚度测量仪进行测试；测量每个测试点的厚度实测值，并取算数平均值。Method 1: Cut the sample from the diaphragm. The number of test points depends on the condition of the diaphragm (usually no less than 10 points); test it with a ten thousandth thickness measuring instrument under the condition of 23±2℃; measure the actual thickness value of each test point. and take the arithmetic mean.
方式二：Method two:
a.取样：对于宽度＜200mm的产品：沿纵向(machine direction，MD)方向每隔40mm±5mm确定一个点，测试点数不小于10个，测试点数可以视隔膜宽度而定，其中，测量起点距边部不小于20mm；对于宽度≥200mm的产品：沿横向(transverse direction，TD)方向每隔80mm±5mm确定一个点，测试点数不小于10个，测试点数可以视隔膜宽度而定，其中，测量起点距边部不小于20mm。a. Sampling: For products with a width less than 200mm: Determine a point every 40mm±5mm along the machine direction (MD). The number of test points is not less than 10. The number of test points can depend on the width of the diaphragm. Among them, the starting point distance of the measurement The edge is not less than 20mm; for products with a width ≥ 200mm: determine a point every 80mm±5mm along the transverse direction (TD) direction, and the number of test points is not less than 10. The number of test points can depend on the width of the diaphragm. Among them, measurement The starting point is not less than 20mm from the edge.
b.测试：在23±2℃条件下通过厚度测量仪对每个测试点进行测试，测量面的直径应在2.5mm～10mm之间，测量面对试样施加的负荷应在0.5N～1.0N之间。b. Test: Test each test point with a thickness measuring instrument at 23±2°C. The diameter of the measuring surface should be between 2.5mm and 10mm, and the load applied to the sample on the measuring surface should be between 0.5N and 1.0 between N.
c.数据处理：测量每个测试点的厚度实测值，并取算数平均值。c. Data processing: measure the actual thickness value of each test point and take the arithmetic average.
2)150℃热收缩率2) Thermal shrinkage rate at 150℃
a.取样：全幅宽随机裁取6个试样，每个试样的具体取样可以包括：沿隔膜的MD方向，裁取100mm；当隔膜的TD方向大于100mm时，测试样品在TD方向上的长度可以为100mm；当微孔膜TD方向小于100mm时，测试样品在TD方向上的长度可以以实际为准。a. Sampling: randomly cut 6 samples from the full width. The specific sampling of each sample can include: cut 100mm along the MD direction of the diaphragm; when the TD direction of the diaphragm is greater than 100mm, test the sample in the TD direction. The length can be 100mm; when the TD direction of the microporous membrane is less than 100mm, the length of the test sample in the TD direction can be subject to actual conditions.
b.测试：标记好样品的纵、横向标识，测量并记录每片试样纵横向的尺寸；将试样平置于纸夹套层中，试样无折叠、起皱、粘连等情况；将夹有试样的纸套(层数例如可以为10层)平整地放入恒温烘箱中部(开门时间例如不超过3s，)；通过电热恒温箱加热试样至150℃，加热时间为1h；取出试样后 冷却至室温，测量纵向长度和横向长度。b. Test: Mark the longitudinal and transverse markings of the sample, measure and record the longitudinal and transverse dimensions of each sample; place the sample flat in the paper jacket layer, and make sure there is no folding, wrinkling, adhesion, etc. of the sample; The paper sleeve with the sample sandwiched therein (the number of layers can be, for example, 10) is placed flatly into the middle of the constant temperature oven (the door opening time is, for example, no more than 3 seconds); the sample is heated to 150°C by the electric thermostatic oven, and the heating time is 1 hour; take it out. After sample Cool to room temperature and measure the longitudinal and transverse lengths.
c.数据处理：计算各个样本的热收缩率：c. Data processing: Calculate the thermal shrinkage rate of each sample:
T＝(L0-L)/L0×100％，其中，T可以为试样热收缩率(％)，L0可以为加热前试样的长度(mm)，L可以为加热后试样的长度(mm)。计算样本MD，TD方向热收缩率的算术平均值。T=(L 0 -L)/L 0 ×100%, where T can be the thermal shrinkage rate of the sample (%), L 0 can be the length of the sample before heating (mm), and L can be the sample after heating length (mm). Calculate the arithmetic mean of the thermal shrinkage in the MD and TD directions of the sample.
3)破膜温度(℃)3) Membrane rupture temperature (℃)
采用烘烤法测试破膜温度：将复合隔膜置于8×8cm的夹具内，将上述夹具置于烘箱中，以一定速度进行升温，同时监控夹具内隔膜是否破膜，当隔膜随温度变化隔膜破膜，记录为隔膜的破膜温度。Use the baking method to test the membrane rupture temperature: place the composite diaphragm in an 8×8cm clamp, place the above clamp in the oven, and heat it at a certain speed. At the same time, monitor whether the membrane in the clamp is broken. When the membrane changes with the temperature, the membrane ruptures. Membrane rupture was recorded as the membrane rupture temperature.
4)透气度(S)4) Breathability (S)
按照标准JIS P8117-2009规定的方法进行测试。汽缸驱动减压阀0.25MPa，测试压0.05MPa。记录所测点的值，测试5次取平均值。Test according to the method specified in standard JIS P8117-2009. The cylinder drives the pressure reducing valve 0.25MPa, and the test pressure is 0.05MPa. Record the value of the measured point, test 5 times and take the average value.
5)阻抗(Ω/cm2)5) Impedance (Ω/cm 2 )
将复合隔膜剪裁到可覆盖到测试用电极的大小，之后浸泡在1M LiBF4电解液24小时后，使用不锈钢电极通过交流阻抗法测试复合隔膜阻抗，测试条件为交流电压10mV，频率在1MHz-10mHz的范围，根据电极面积换算其阻抗。同一种隔膜测3次，其平均值为该隔膜阻抗。Cut the composite separator to a size that can cover the test electrode, and then soak it in 1M LiBF 4 electrolyte for 24 hours. Use stainless steel electrodes to test the impedance of the composite separator by the AC impedance method. The test conditions are AC voltage 10mV and frequency 1MHz-10mHz. range, and its impedance is converted according to the electrode area. The same diaphragm is measured three times, and the average value is the impedance of the diaphragm.
表1
Table 1
表2
Table 2
由表1中的实施例1-6的测试数据可以看出，本申请实施例的复合隔膜的破膜温度均可达到300℃及以上，复合隔膜的阻抗也均小于1Ω/cm2，且阻抗增加率也小于50％，其中，阻抗增加率基本在30％以内。这说明，本申请的复合隔膜中，耐热涂层可具有较低的阻抗，对整个复合隔膜的阻抗影响较小，可获得低阻抗隔膜。另外，由实施例1、实施例4-6的对比数据可知，当无机粒子的比表面积在60～110m2/g范围内时，可获得收缩率更低、阻抗更低的复合隔膜。It can be seen from the test data of Examples 1-6 in Table 1 that the membrane rupture temperature of the composite separators in the embodiments of the present application can reach 300°C and above, and the impedance of the composite separators is also less than 1Ω/cm 2 , and the impedance The increase rate is also less than 50%, and the impedance increase rate is basically within 30%. This shows that in the composite separator of the present application, the heat-resistant coating can have a lower impedance and have less impact on the impedance of the entire composite separator, and a low-impedance separator can be obtained. In addition, it can be seen from the comparative data of Example 1 and Examples 4-6 that when the specific surface area of the inorganic particles is in the range of 60 to 110 m 2 /g, a composite separator with lower shrinkage rate and lower impedance can be obtained.
由表1和表2的对比数据可以看出，本申请实施例的复合隔膜的阻抗要远小于对比例1、3、4。对比例2使用了比表面积为300m2/g的多孔粒子，虽然获得的复合隔膜的阻抗较小，但收缩率要高于本申请各实施例的复合隔膜，且对比例2的破膜温度低于本申请各实施例的复合隔膜。It can be seen from the comparative data in Table 1 and Table 2 that the impedance of the composite separator of the embodiment of the present application is much smaller than that of Comparative Examples 1, 3, and 4. Comparative Example 2 uses porous particles with a specific surface area of 300 m 2 /g. Although the resistance of the composite separator obtained is small, the shrinkage rate is higher than that of the composite separators of various embodiments of the present application, and the membrane rupture temperature of Comparative Example 2 is low. Composite separators in various embodiments of the present application.
其中，以实施例2和对比例4的相关数据可以看出，通过改变复合隔膜制备过程中的干燥工艺和热固定工艺，可显著降低复合隔膜的阻抗，从而获得低收缩率、高破膜温度和低阻抗的复合隔膜。另外，从实施例1和实施例7的相关测试数据可知，当优化干燥工艺以及热固定工艺后，还可进一步降低所得复合隔膜的收缩率。Among them, it can be seen from the relevant data of Example 2 and Comparative Example 4 that by changing the drying process and heat fixing process in the preparation process of the composite separator, the impedance of the composite separator can be significantly reduced, thereby obtaining low shrinkage and high membrane rupture temperature. and low-impedance composite diaphragms. In addition, it can be seen from the relevant test data of Example 1 and Example 7 that when the drying process and the heat fixing process are optimized, the shrinkage rate of the obtained composite separator can be further reduced.
由实施例1和对比例5的测试数据还可看出，对比例5中，当利用传统工艺，例如在耐热涂层中使用无孔无机粒子，且在耐热涂层浆料中通过添加造孔剂以提高耐热涂层的孔径率，降低复合隔膜的透气度，其中，复合隔膜的透气度越低，代表复合隔膜耐热高分子间的间距越大，活性离子的穿透性越高，该方法虽可达到降低复合隔膜的阻抗的目的，但是该复合隔膜的耐热性能明显下降，如破膜温度明显降低，且热收缩率明显增大。该对比例所对应的复合隔膜已不能满足二次电池对隔膜热稳定性的要求。而本申请实施例1的复合隔膜，通过选用特定比表面积的多孔无机粒子，可在不改变复合隔膜透气度的基础上，获得低阻抗的复合隔膜。It can also be seen from the test data of Example 1 and Comparative Example 5 that in Comparative Example 5, when using traditional processes, such as using non-porous inorganic particles in the heat-resistant coating, and adding The pore-forming agent is used to increase the pore size of the heat-resistant coating and reduce the air permeability of the composite separator. The lower the air permeability of the composite separator, the greater the distance between the heat-resistant polymers of the composite separator and the greater the penetrability of active ions. Although this method can achieve the purpose of reducing the impedance of the composite separator, the heat resistance of the composite separator is significantly reduced, such as the membrane rupture temperature is significantly reduced, and the thermal shrinkage rate is significantly increased. The composite separator corresponding to this comparative example can no longer meet the thermal stability requirements of secondary batteries for separators. As for the composite separator in Example 1 of the present application, by selecting porous inorganic particles with a specific specific surface area, a low-impedance composite separator can be obtained without changing the air permeability of the composite separator.
综上，本申请实施例的复合隔膜，通过采用特定比表面积的多孔无机粒子，既可满足热稳定性的要求，又可满足低阻抗的多种效果。 In summary, the composite separator of the embodiment of the present application can not only meet the requirements of thermal stability but also achieve various effects of low impedance by using porous inorganic particles with a specific specific surface area.
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。因此，本申请的保护范围应以权利要求的保护范围为准。 The above are only specific embodiments of the present application, but the protection scope of the present application is not limited thereto. Any person familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, and all of them should be covered. within the protection scope of this application. Therefore, the protection scope of this application should be subject to the protection scope of the claims.

Claims (10)

  1. 一种复合隔膜，其特征在于，包括基膜和结合于所述基膜至少一侧表面的耐热涂层，所述耐热涂层包括耐热树脂和无机粒子，所述耐热树脂与所述无机粒子的质量比≤6:4，所述无机粒子为多孔结构，所述无机粒子的比表面积为50～150m2/g，所述复合隔膜的阻抗≤1Ω/cm2。A composite separator, characterized by comprising a base film and a heat-resistant coating bonded to at least one side surface of the base film, the heat-resistant coating including heat-resistant resin and inorganic particles, the heat-resistant resin and the The mass ratio of the inorganic particles is ≤6:4, the inorganic particles have a porous structure, the specific surface area of the inorganic particles is 50-150m2 /g, and the impedance of the composite separator is ≤1Ω/ cm2 .
  2. 根据权利要求1所述的复合隔膜，其特征在于，所述无机粒子的比表面积为60～150m2/g。The composite separator according to claim 1, wherein the specific surface area of the inorganic particles is 60 to 150 m 2 /g.
  3. 根据权利要求1或2所述的复合隔膜，其特征在于，所述复合隔膜的阻抗增加率≤50％，其中，复合隔膜的阻抗增加率＝(复合隔膜阻抗-基膜阻抗)/基膜阻抗×100％。The composite separator according to claim 1 or 2, characterized in that the impedance increase rate of the composite separator is ≤50%, wherein the impedance increase rate of the composite separator=(composite separator impedance-base film impedance)/base film impedance ×100%.
  4. 根据权利要求1-3任一项所述的复合隔膜，其特征在于，所述复合隔膜的破膜温度≥300℃。The composite separator according to any one of claims 1 to 3, characterized in that the membrane rupture temperature of the composite separator is ≥300°C.
  5. 根据权利要求1-4任一项所述的复合隔膜，其特征在于，所述耐热树脂包括芳纶。The composite membrane according to any one of claims 1 to 4, wherein the heat-resistant resin includes aramid.
  6. 一种如权利要求1-5任一项所述的复合隔膜的制备方法，其特征在于，包括：A method for preparing a composite separator according to any one of claims 1 to 5, characterized in that it includes:
    涂覆有耐热涂层浆料的基膜经干燥和热固定后得到所述复合隔膜；其中，干燥温度为50～120℃，干燥时间≤10min；热固定温度为60～150℃，热固定时间为≤5min。The base film coated with the heat-resistant coating slurry is dried and heat-fixed to obtain the composite separator; wherein the drying temperature is 50-120°C and the drying time is ≤10 min; the heat-fixing temperature is 60-150°C and the heat-fixing The time is ≤5min.
  7. 根据权利要求6所述的制备方法，其特征在于，所述干燥温度为50～100℃，所述干燥时间≤5min。The preparation method according to claim 6, characterized in that the drying temperature is 50-100°C, and the drying time is ≤5 min.
  8. 根据权利要求6或7所述的制备方法，其特征在于，所述热固定温度为60～110℃，所述热固定时间为≤2min。The preparation method according to claim 6 or 7, characterized in that the heat fixing temperature is 60-110°C, and the heat fixing time is ≤2 min.
  9. 一种二次电池，其特征在于，包括正极片、负极片、以及设置所述正极片和所述负极片之间的如权利要求1-5任一项所述的复合隔膜。A secondary battery, characterized by comprising a positive electrode sheet, a negative electrode sheet, and the composite separator according to any one of claims 1 to 5 disposed between the positive electrode sheet and the negative electrode sheet.
  10. 一种用电设备，其特征在于，包括如权利要求9所述的二次电池。 An electrical device, characterized by comprising the secondary battery according to claim 9.
PCT/CN2023/104146 2022-07-06 2023-06-29 Composite separator and preparation method therefor, secondary battery and electric device WO2024007964A1 (en)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH11260338A (en) * 1998-03-09 1999-09-24 Nippon Muki Co Ltd Nonaqueous electrolyte battery and separator thereof
CN103618059A (en) * 2013-12-10 2014-03-05 深圳市星源材质科技有限公司 Lithium ion battery diaphragm with polymer inorganic coating and preparation method for lithium ion battery diaphragm
CN105765761A (en) * 2013-11-29 2016-07-13 丰田自动车株式会社 Separator for nonaqueous electrolyte secondary battery, and battery including same
CN111446404A (en) * 2020-04-02 2020-07-24 惠州锂威电子科技有限公司 Diaphragm for lithium ion battery, preparation method of diaphragm and lithium ion battery
CN111492504A (en) * 2017-12-27 2020-08-04 帝人株式会社 Separator for nonaqueous secondary battery and nonaqueous secondary battery

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH11260338A (en) * 1998-03-09 1999-09-24 Nippon Muki Co Ltd Nonaqueous electrolyte battery and separator thereof
CN105765761A (en) * 2013-11-29 2016-07-13 丰田自动车株式会社 Separator for nonaqueous electrolyte secondary battery, and battery including same
CN103618059A (en) * 2013-12-10 2014-03-05 深圳市星源材质科技有限公司 Lithium ion battery diaphragm with polymer inorganic coating and preparation method for lithium ion battery diaphragm
CN111492504A (en) * 2017-12-27 2020-08-04 帝人株式会社 Separator for nonaqueous secondary battery and nonaqueous secondary battery
CN111446404A (en) * 2020-04-02 2020-07-24 惠州锂威电子科技有限公司 Diaphragm for lithium ion battery, preparation method of diaphragm and lithium ion battery

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