WO2023098044A1 - 一种导热锂离子隔膜及其制备方法 - Google Patents

一种导热锂离子隔膜及其制备方法 Download PDF

Info

Publication number
WO2023098044A1
WO2023098044A1 PCT/CN2022/100730 CN2022100730W WO2023098044A1 WO 2023098044 A1 WO2023098044 A1 WO 2023098044A1 CN 2022100730 W CN2022100730 W CN 2022100730W WO 2023098044 A1 WO2023098044 A1 WO 2023098044A1
Authority
WO
WIPO (PCT)
Prior art keywords
particles
aluminum nitride
thermally conductive
base film
lithium ion
Prior art date
Application number
PCT/CN2022/100730
Other languages
English (en)
French (fr)
Inventor
庄志
唐亚奇
齐岭
王伟强
王康
刘倩倩
程跃
Original Assignee
上海恩捷新材料科技有限公司
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 上海恩捷新材料科技有限公司 filed Critical 上海恩捷新材料科技有限公司
Publication of WO2023098044A1 publication Critical patent/WO2023098044A1/zh

Links

Images

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • 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
    • H01M50/431—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
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/449—Separators, membranes or diaphragms characterised by the material having a layered structure
    • 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 application belongs to the field of separators, and in particular relates to a method for preparing a battery separator using heat-conducting particles mixed with a ceramic coating.
  • lithium-ion batteries need to solve the problems of cruising range and charging time, and lithium-ion batteries have energy density, capacity and power density.
  • the promotion of fast charging technology has also become an important development direction of the lithium-ion battery market.
  • a large amount of heat will be generated inside and it is difficult to dissipate it evenly and effectively, which will cause accelerated attenuation and other safety problems, hinder the development of new energy vehicles, and make the internal heat dissipation problem become a prominent problem. safety hazards.
  • lithium-ion batteries mainly include four major materials: positive electrode, negative electrode, diaphragm, and electrolyte, among which the diaphragm element has the worst thermal conductivity.
  • Most of the traditional heat-resistant separator materials are coated with alumina, which can improve the thermal stability and wettability of the separator, and can basically meet the needs of existing lithium-ion batteries.
  • traditional separators cannot achieve the expected excellent improvement in terms of adapting to the fast charging environment, rapid heat conduction, and heat dissipation, and the moisture content is generally high, resulting in the problem of focusing on one thing and losing another.
  • the invention focuses on solving the problems of battery safety and performance attenuation caused by the excessive heat inside the lithium battery that cannot be effectively and quickly dissipated, develops a new type of lithium ion separator, and introduces an aluminum nitride coating material pioneeringly.
  • one object of the present invention is to provide a thermally conductive lithium-ion separator, which includes: a base film and a thermally conductive coating disposed on one surface of the base film, wherein the thermally conductive coating includes inorganic particles , ceramic particles, aluminum nitride particles, organic binder or a combination thereof; wherein, the inorganic particles include ceramic particles, aluminum nitride particles, and the ceramic particles and the aluminum nitride particles are evenly distributed on the base film above, wherein, taking one surface of the base film as a horizontal reference, the aluminum nitride particles are 1 to 3 ⁇ m taller than the adjacent ceramic particles, and the aluminum nitride particles have a weight per unit area of 1.5 to 3 g/m 2 is disposed on the base film.
  • the thermally conductive lithium-ion separator wherein the average particle size of the ceramic particles is between 0.6-1.5 ⁇ m, and the average particle size of the aluminum nitride is between 4-6 ⁇ m.
  • the thermally conductive lithium ion separator wherein the weight ratio of the ceramic particles to aluminum nitride is between 5:1 and 1:1.2.
  • the specific surface area of the aluminum nitride particles is smaller than the specific surface area of the ceramic particles.
  • the thermally conductive lithium ion separator wherein the specific surface area of the ceramic particles is 3-9 m 2 /g, and the specific surface area of the aluminum nitride particles is 2-5 m 2 /g.
  • the thermally conductive lithium ion separator wherein the thermally conductive coating further includes an organic solvent, and the proportion of the organic solvent to the dry weight of the inorganic particles is between 3% and 5%.
  • the thermally conductive lithium ion separator wherein the thermal conductivity of the ceramic particles is 25-35 W/m ⁇ K, and the thermal conductivity of the aluminum nitride particles is 250-320 W/m ⁇ K.
  • the thermally conductive lithium-ion separator wherein the thickness of the base film is in the range of 5-12 ⁇ m, and the porosity is 45%-55%.
  • the thermally conductive lithium ion separator wherein the base film includes a PE material base film, and the PE material base film is composed of high molecular weight PE particles, and the molecular weight of the high molecular weight PE particles is between 1.1 million and 3.1 million.
  • the thermally conductive lithium-ion separator wherein the Ca content of the aluminum nitride particles is ⁇ 100ppm, the Si content is ⁇ 10ppm, and the Fe content is ⁇ 10ppm.
  • the thermally conductive lithium ion separator wherein the ceramic particles include alumina, boehmite or a combination thereof.
  • Another object of the present invention is to provide a method for preparing a thermally conductive lithium ion diaphragm, comprising the steps of: 1) providing a base film; 2) mixing ceramic particles and aluminum nitride to obtain a mixed slurry; and 3) mixing the The mixed slurry is coated on at least one surface of the base film to obtain the thermally conductive lithium ion diaphragm, wherein the mixed slurry is coated at a coating speed by a wire rod or a gravure roll, and the coated Cloth speed is between 50m/min-80m/min,
  • Another object of the present invention is to provide a lithium-ion battery separator, which includes the heat-conductive lithium-ion separator prepared by the above-mentioned method.
  • the thermally conductive lithium-ion diaphragm provided by the present invention exposes more aluminum nitride. Based on the excellent thermal conductivity of aluminum nitride itself, the heat transfer path of the diaphragm is greatly shortened, which is conducive to the excessive heat inside the battery through heat conduction. The role of the diaphragm makes the path of heat conduction from the positive and negative plates to the tabs smoother.
  • the thermally conductive lithium-ion diaphragm provided by the present invention adopts a base film made of high-molecular-weight PE particles, which has better physical and chemical properties, improves the energy density of the battery, and achieves good liquid absorption by controlling the porosity of the diaphragm High performance and lower internal resistance are conducive to the improvement of battery electrochemical performance.
  • the thermally conductive lithium ion separator provided by the present invention uses a coating material containing trace elements such as Ca, Si, Fe, etc., within the content range, the prepared separator can prevent micro-short circuit inside the battery.
  • the preparation method of the heat-conducting lithium-ion separator provided by the present invention adopts the technical idea of mixing large particles with small particles, and obtains the effect that the particles are easier to disperse in the slurry preparation, so that the particles in the subsequent slurry coating are on the base film
  • the distribution is more uniform, which solves the technical defects of the conventional technology, such as the high difficulty of dispersion after mixing with small particles, easy agglomeration, and the lack of heat resistance effect when using large particles;
  • aluminum nitride with larger particle size is selected The thermal conductivity of aluminum nitride is fully utilized, so that the separator exhibits better thermal conductivity inside the battery.
  • Fig. 1 is a schematic diagram of the preparation and composition of the thermally conductive lithium ion separator provided by the present invention.
  • Fig. 2 is a SEM image of the thermally conductive lithium ion separator provided by the present invention.
  • FIG. 3 is a specific flow chart of the method for preparing a thermally conductive lithium-ion separator provided by the present invention.
  • the main function of the separator in the battery is to prevent the short circuit of the positive and negative electrodes and allow lithium ions to shuttle back and forth in the separator. It plays an important role in ensuring the safety performance of the battery.
  • the internal thermal effect prevents the temperature from spreading out quickly through the separator, which greatly increases the safety risk of the battery.
  • the present invention proposes a new thermal conductive coating, which mainly adds aluminum nitride particles with better thermal conductivity to the traditional alumina or boehmite coating to achieve complementary advantages.
  • the good thermal conductivity also improves the heat resistance of the thermally conductive lithium-ion separator, which greatly increases the safety performance of the battery.
  • thermally conductive lithium ion separator provided by the invention has better thermal conductivity, heat resistance, lower moisture and internal resistance.
  • the advantages of the present invention will be described in detail below in conjunction with specific specific examples and accompanying drawings.
  • a thermally conductive lithium ion diaphragm which includes a base film 1 and a thermally conductive coating, disposed on one surface of the base film 1, wherein the thermally conductive coating includes inorganic particles, an organic binder 4 or a combination thereof ; wherein the inorganic particles include ceramic particles 2 and aluminum nitride particles 3, and the ceramic particles and the aluminum nitride particles are evenly distributed on the base film, wherein one surface of the base film is horizontal On a basis, the aluminum nitride particles are 1-3 ⁇ m taller than the adjacent ceramic particles, and the aluminum nitride particles are disposed on the base film with a unit area weight of 1.5-3 g/m 2 .
  • Fig. 1 is a schematic diagram of the structure of the heat-conducting lithium-ion diaphragm provided by the present invention; specifically, as can be seen from Fig. 1-3 ⁇ m higher than the coating of ceramic particles 2, based on the excellent thermal conductivity of aluminum nitride itself, the weight per unit area of the aluminum nitride particles 3 on the base film 1 is between 1.5-3 g/m 2 , thus obtaining
  • the thermally conductive lithium-ion diaphragm exposes more aluminum nitride, shortens the heat transfer path of the diaphragm, and facilitates the excessive internal heat to pass through the thermally conductive diaphragm, making the heat conduction from the positive and negative pole pieces to the tabs more smooth, nitriding
  • the aluminum particles 3 can be in any shape, which can be ellipsoidal, rod-shaped, massive, spherical, and flake-shaped, and the aluminum nitride particles 2 are preferably ellipsoidal in shape;
  • Fig. 2 is an enlarged view of a scanning electron microscope (Scanning Electron Microscopy, SEM), showing the surface structure of a thermally conductive coating in an example of the present invention, and it can be clearly seen that ceramic particles and aluminum nitride The morphology and distribution of inorganic particles of different sizes are evenly distributed on the base film. If the aluminum nitride particles are simply mixed with ceramic particles, the effect of improving thermal conductivity cannot be obtained; wherein, the average of the ceramic particles The particle size is between 0.6-1.5 ⁇ m, and the average particle size of the aluminum nitride is between 4-6 ⁇ m.
  • the thermally conductive coating is obtained by coating a coating slurry through a coating machine, wherein the coating slurry has a solid content of 28%-38%, contains water, inorganic particles, organic solvents, water and inorganic
  • the ratio of particles is between 1.5:1 and 2.5:1; in some examples, the inorganic particles include ceramic particles and aluminum nitride particles, and the inorganic particles are made by mixing ceramic particles and aluminum nitride particles according to a certain ratio , wherein the ratio of ceramic particles to aluminum nitride is between 5:1 and 1:1.2, and the proportion of organic solvent to the dry weight of inorganic particles is between 3% and 5%; preferably, the ceramic particles include alumina, Boehmite or combinations thereof.
  • the Ca content in the aluminum nitride particles is ⁇ 100ppm, the Si content is ⁇ 10ppm, and the Fe content is ⁇ 10ppm; in the aluminum nitride particles, the metal foreign matter content is small, which can prevent micro-short circuits inside the battery and improve the performance of the battery. Internal electrochemical performance and safety performance.
  • the thermal conductivity of the ceramic particles is 25-35W/m ⁇ K
  • the thermal conductivity of the aluminum nitride particles is 250-320W/m ⁇ K
  • traditional alumina coating materials cannot meet the high requirements of lithium-ion separators.
  • the introduction of aluminum nitride greatly increases the thermal conductivity of the diaphragm
  • the thermal conductivity of traditional coating films is between 10-30W/m ⁇ K
  • the thermal conductivity of the lithium ion diaphragm provided by the present invention has a thermal conductivity of 100-210W/m Between K.
  • the improvement of thermal conductivity can speed up the diffusion speed of heat inside the battery to the pole piece through the separator, so that the safety performance of the battery is greatly improved.
  • the average particle diameter D50 of the ceramic particles is 0.6-1.5 ⁇ m
  • the average particle diameter D50 of the aluminum nitride particles is 4-6 ⁇ m
  • the specific surface area of the aluminum nitride particles is smaller than the specific surface area of the ceramic particles ; More specifically, the specific surface area of ceramic particles is 3-9m 2 /g, and the specific surface area of aluminum nitride is 2-5m 2 /g; the lower specific surface area of aluminum nitride can reduce the particle surface energy (Surface energy), reduce agglomeration, It is beneficial to exert better dispersion performance in the coating slurry subsequently.
  • the base film adopts high molecular weight PE particles with a molecular weight of 1.10-3.1 million; the thickness of the base film is in the range of 5-12 ⁇ m, preferably 9 ⁇ m, and the porosity is 45%-55%, preferably Porosity 50%.
  • the high porosity reduces the gas permeability of the separator, thereby reducing the internal resistance of the separator, and is beneficial to improve the electrochemical performance of the battery.
  • the organic solvent includes a binder and a wetting agent; the binder is selected from one or more combinations of water solvent type or emulsion type, and the binder is mainly acrylic resin or acrylic acid
  • the copolymer is selected from one or more combinations of acrylic resins, PMMA, PVDF, and polyvinyl alcohol, and its structure contains modified groups such as carboxyl and hydroxyl groups; through the modified groups, performance can be increased according to requirements.
  • the applicability of the thermally conductive lithium ion separator is expanded; more specifically, the ratio of the binder to the wetting agent is between 100:1 and 50:1.
  • Another embodiment of the present invention is a method for preparing a thermally conductive lithium-ion separator, which is mainly divided into three steps: provision of wet base film—preparation of coating slurry—slurry coating. More specifically, please refer to FIG. 3, It is a specific flow chart illustrating the preparation method of this embodiment, and the method includes steps:
  • the method further comprises the steps of:
  • the drying temperature is between 70 ° C and 100 ° C; specifically, the mixed slurry is coated to obtain the lithium ion diaphragm, which is transferred to at least two ovens for drying ,
  • the oven temperature is controlled at 70°C-100°C, preferably 85°C.
  • the thickness of the sample is measured by a MahrMillimar thickness gauge. Test conditions: A) The measurement surface is flat; B) The measurement surface diameter: ⁇ 12mm; C) The measurement surface load: 0.75N.
  • the cross-sectional morphology of the thermally conductive lithium-ion diaphragm was photographed by a field emission scanning electron microscope SEM, and the height was tested.
  • the aluminum nitride: ceramic particles is X
  • the actual weight per unit area of the heat conduction film can be measured as Y1
  • the corresponding base film is Y2
  • the aluminum nitride particles are in The weight per unit area of the base film is (Y1-Y2) ⁇ (X/1+X)
  • the equipment is measured by Mettler Toledo XS205 electronic balance with an accuracy of 0.1mg.
  • inductively coupled plasma optical emission spectrometer ICP-OES-5110VDV before testing the sample, adjust the time for not less than 4h at a temperature of 23°C ⁇ 2°C and a humidity of 50% ⁇ 10%.
  • Test conditions RF power: 1300W, plasma air flow: 10L/min, auxiliary gas flow: 0.3L/min, atomizer flow: 0.7L/min, observation height: 15mm.
  • Test conditions The refractive index of the selected material to be tested: 1.8, the refractive index of the dispersion medium: 1.33, the shading ratio: 6-9, the number of samples: 3 times.
  • the specific surface area measuring instrument can measure the specific surface area of solid matter according to GB/T 19587-2004 gas adsorption BET method.
  • a thermal conductivity meter Measured by a thermal conductivity meter, a sample of a certain thickness is placed between two upper and lower plates, a certain heat flow and pressure are applied to the sample, and a heat flow sensor is used to measure the heat flow through the sample, the thickness of the test sample, and the temperature between the hot plate/cold plate Gradient, and then obtain the corresponding thermal resistance data under different thicknesses for linear fitting to obtain the thermal conductivity of the sample.
  • a Karl Fischer moisture analyzer is used, and the test conditions are as follows: weigh a sample with a mass of 0.1g-0.15g, a test temperature of 180°C, and a test time of 5 minutes.
  • the provided PE base film is prepared according to the conventional wet process.
  • the base film obtained by this process has high porosity, uniform pore size, high mechanical strength, good safety and can be prepared in thickness Ultra-thin products; in this example, the thickness of the base film is preferably 9 ⁇ m and the porosity is 50%.
  • the preparation process of the base film of this thickness is mature, the consistency of the diaphragm is good, the porosity can be adjusted arbitrarily, and it has outstanding mechanical properties and safety performance .
  • Preparation of coating slurry water and carboxymethyl cellulose (Carboxymethyl Cellulose, CMC) are mixed in a ratio of 100:1 to 100:5, and water and CMC are mechanically stirred to obtain a transparent and clear CMC solution.
  • CMC carboxymethyl Cellulose
  • the semi-finished slurry is ground to fully disperse the particles in the slurry, and then add a certain amount of organic solvent, including binder and wetting agent; the dry weight ratio of organic solvent to inorganic particles is 2.5%.
  • stir at a certain speed to uniformly mix the organic solvent and the semi-finished slurry to form a finished coating slurry.
  • Slurry coating the slurry is coated on the above-mentioned base film by a wire bar method or a gravure roll.
  • the thickness of the ceramic coating is 3 ⁇ m, and the coating slurry is coated on at least one surface of the base film.
  • the cloth speed is 80m/min, and the temperature of the coating oven is 85°C; the aforementioned coating oven has 2 sections, and the temperature of each section can be adjusted according to the actual situation.
  • Example 2 After the thermally conductive lithium-ion separator prepared in Example 1 was tested by the aforementioned test method, its thermal conductivity was measured to be 170W/m ⁇ K, and its thermal contraction coefficient was 6% (MD) and 6% (TD), respectively. The moisture is 721ppm, and the internal resistance is 1.37 ⁇ *cm 2 .
  • the dry weight ratio of organic solvent to inorganic particles is 5.5%.
  • the weight ratio of ceramic particles to aluminum nitride is 1:1.5.
  • the D50 of the aluminum nitride particles was 4 ⁇ m, and the weight per unit area was 3 g/m 2 .
  • the D50 of the ceramic particles was 0.6 ⁇ m, and the specific surface area was 10 m 2 /g.
  • the thermally conductive lithium ion separator prepared in Example 2 has a thermal conductivity of 175W/m ⁇ K, a thermal shrinkage coefficient of 6% (MD) and 5% (TD) respectively, a moisture content of 679ppm, and an internal resistance of 1.38 ⁇ *cm 2 .
  • the D50 of the aluminum nitride particles was 6 ⁇ m, and the weight per unit area was 2 g/m 2 .
  • the D50 of the ceramic particles was 1.5 ⁇ m, and the specific surface area was 3 m 2 /g.
  • the thermally conductive lithium ion separator prepared in Example 3 has a thermal conductivity of 183W/m K, a thermal shrinkage coefficient of 6% (MD) and 5% (TD) respectively, a moisture content of 664ppm, and an internal resistance of 1.36 ⁇ *cm 2 .
  • the dry weight ratio of organic solvent to inorganic particles is 2.5%.
  • the weight ratio of ceramic particles to aluminum nitride is 5:1.
  • Aluminum nitride particles contain Ca ppm ⁇ 100, Si ppm ⁇ 10, Fe ppm ⁇ 10; D50 is 5 ⁇ m; specific surface area is 5m 2 /g, and weight per unit area is 1.7g/m 2 .
  • the D50 of the ceramic particles was 0.8 ⁇ m, and the specific surface area was 9 m 2 /g.
  • the thermally conductive lithium ion separator prepared in Example 4 has a thermal conductivity of 191W/m ⁇ K, a thermal shrinkage coefficient of 6% (MD) and 4% (TD) respectively, a moisture content of 658ppm, and an internal resistance of 1.33 ⁇ *cm 2 .
  • the dry weight ratio of organic solvent to inorganic particles is 5.5%.
  • the weight ratio of ceramic particles to aluminum nitride is 2:1.
  • Aluminum nitride particles contain Ca ppm ⁇ 100, Si ppm ⁇ 10, Fe ppm ⁇ 10; D50 is 5 ⁇ m; specific surface area is 4m 2 /g, and weight per unit area is 2g/m 2 .
  • the D50 of the ceramic particles was 1 ⁇ m, and the specific surface area was 4 m 2 /g.
  • the thermally conductive lithium ion separator prepared in Example 5 has a thermal conductivity of 194W/m ⁇ K, a thermal shrinkage coefficient of 5% (MD) and 5% (TD) respectively, a moisture content of 645ppm, and an internal resistance of 1.35 ⁇ *cm 2 .
  • the dry weight ratio of organic solvent to inorganic particles is 3.0%.
  • the weight ratio of ceramic particles to aluminum nitride is 3:1.
  • Aluminum nitride particles contain Ca ppm ⁇ 100, Si ppm ⁇ 10, Fe ppm ⁇ 10; D50 is 5 ⁇ m; specific surface area is 4m 2 /g, and weight per unit area is 1.9g/m 2 .
  • the D50 of the ceramic particles was 0.8 ⁇ m, and the specific surface area was 8 m 2 /g.
  • the thermally conductive lithium ion separator prepared in Example 6 has a thermal conductivity of 200W/m ⁇ K, a thermal shrinkage coefficient of 5% (MD) and 4% (TD) respectively, a moisture content of 633ppm, and an internal resistance of 1.36 ⁇ *cm 2 .
  • the dry weight ratio of organic solvent to inorganic particles is 3.5%.
  • the weight ratio of ceramic particles to aluminum nitride is 2:1.
  • Aluminum nitride particles contain Ca ppm ⁇ 100, Si ppm ⁇ 10, Fe ppm ⁇ 10; D50 is 5 ⁇ m; specific surface area is 4m 2 /g, and weight per unit area is 2g/m 2 .
  • the D50 of the ceramic particles was 0.8 ⁇ m, and the specific surface area was 5 m 2 /g.
  • the thermally conductive lithium ion separator prepared in Example 7 has a thermal conductivity of 204W/m ⁇ K, a thermal shrinkage coefficient of 5% (MD) and 3% (TD) respectively, a moisture content of 620ppm, and an internal resistance of 1.32 ⁇ *cm 2 .
  • the dry weight ratio of organic solvent to inorganic particles is 4.0%.
  • the weight ratio of ceramic particles to aluminum nitride is 1:1.
  • Aluminum nitride particles contain Ca ppm ⁇ 100, Si ppm ⁇ 10, Fe ppm ⁇ 10; D50 is 5 ⁇ m; specific surface area is 3m 2 /g, and weight per unit area is 2.5g/m 2 .
  • the D50 of the ceramic particles was 1.3 ⁇ m, and the specific surface area was 7 m 2 /g.
  • the thermally conductive lithium-ion separator prepared in Example 8 has a thermal conductivity of 210W/m K, a thermal shrinkage coefficient of 4% (MD) and 3% (TD) respectively, a moisture content of 600ppm, and an internal resistance of 1.28 ⁇ *cm 2 .
  • the dry weight ratio of organic solvent to inorganic particles is 3.5%.
  • the weight ratio of ceramic particles to aluminum nitride is 1:1.2.
  • Aluminum nitride particles contain Ca ppm ⁇ 100, Si ppm ⁇ 10, Fe ppm ⁇ 10; D50 is 5 ⁇ m; specific surface area is 4m 2 /g, and weight per unit area is 1.9g/m 2 .
  • the D50 of the ceramic particles was 0.8 ⁇ m, and the specific surface area was 5 m 2 /g.
  • the thermally conductive lithium ion separator prepared in Example 9 has a thermal conductivity of 204W/m ⁇ K, a thermal shrinkage coefficient of 5% (MD) and 4% (TD) respectively, a moisture content of 618ppm, and an internal resistance of 1.21 ⁇ *cm 2 .
  • the coating thickness is 5 ⁇ m.
  • the dry weight ratio of organic solvent to inorganic particles is 4.0%.
  • the weight ratio of ceramic particles to aluminum nitride is 1:1.5.
  • the D50 of the aluminum nitride particles is 8 ⁇ m; the specific surface area is 6 m 2 /g, and the weight per unit area is 3 g/m 2 .
  • the D50 of the ceramic particles was 2 ⁇ m, and the specific surface area was 10 m 2 /g.
  • the thermally conductive lithium ion separator prepared in Comparative Example 1 has a thermal conductivity of 162W/m ⁇ K, a thermal shrinkage coefficient of 7% (MD) and 5% (TD) respectively, a moisture content of 740ppm, and an internal resistance of 1.30 ⁇ *cm 2 .
  • the dry weight ratio of organic solvent to inorganic particles is 4.0%.
  • the weight ratio of ceramic particles to aluminum nitride is 1:1.5.
  • the D50 of the aluminum nitride particles is 8 ⁇ m; the specific surface area is 6 m 2 /g, and the weight per unit area is 3.2 g/m 2 .
  • the D50 of the ceramic particles was 8 ⁇ m, and the specific surface area was 6 m 2 /g.
  • the thermally conductive lithium ion separator prepared in Comparative Example 2 has a thermal conductivity of 166W/m ⁇ K, a thermal shrinkage coefficient of 7% (MD) and 6% (TD) respectively, a moisture content of 640ppm, and an internal resistance of 1.20 ⁇ *cm 2 .
  • the dry weight ratio of organic solvent to inorganic particles is 4.0%.
  • the weight ratio of ceramic particles to aluminum nitride is 1:2.
  • the D50 of the aluminum nitride particles is 8 ⁇ m; the specific surface area is 6 m 2 /g, and the weight per unit area is 4 g/m 2 .
  • the D50 of the ceramic particles was 2 ⁇ m, and the specific surface area was 10 m 2 /g.
  • the thermally conductive lithium ion separator prepared in Comparative Example 3 has a thermal conductivity of 140W/m ⁇ K, a thermal shrinkage coefficient of 5% (MD) and 5% (TD) respectively, a moisture content of 740ppm, and an internal resistance of 1.41 ⁇ *cm 2 .
  • the dry weight ratio of organic solvent to inorganic particles is 4.0%.
  • the weight ratio of ceramic particles to aluminum nitride is 1:2.
  • the D50 of the aluminum nitride particles is 5 ⁇ m; the specific surface area is 4 m 2 /g, and the weight per unit area is 4 g/m 2 .
  • the D50 of the ceramic particles was 0.8 ⁇ m, and the specific surface area was 10 m 2 /g.
  • the thermally conductive lithium ion separator prepared in Comparative Example 4 has a thermal conductivity of 160W/m ⁇ K, a thermal shrinkage coefficient of 6% (MD) and 6% (TD) respectively, a moisture content of 612ppm, and an internal resistance of 1.29 ⁇ *cm 2 .
  • the water contained in the thermally conductive lithium-ion separator is mainly related to the content of aluminum nitride particles.
  • the thermal shrinkage tends to decrease, and the thermal shrinkage of aluminum nitride does not decrease, but increases; this is because the aluminum nitride particles are larger, when reaching a certain amount , the packing density on the base film becomes smaller instead, resulting in an increase in thermal shrinkage; the thermal conductivity is improved when the height of aluminum nitride is between 1-3 ⁇ m, and the thermal shrinkage is also smaller; finally, the thermal conductivity of lithium ions
  • the internal resistance of the diaphragm is inversely proportional to the proportion of aluminum nitride, mainly because aluminum nitride can increase the porosity of the coating, making it easier for lithium ions to pass through.
  • the weight per unit area of aluminum nitride also affects the thermal conductivity exhibited by the thermally conductive lithium-ion separator.
  • the weight per unit area of aluminum nitride in Example 1 is 1.5g /m 2 , its thermal conductivity is only 170W/m ⁇ K, and its thermal conductivity cannot meet the demand for high thermal conductivity; in Comparative Examples 2-3, the weights per unit area of aluminum nitride are 3.2 and 4g/m 2 respectively, which are higher than 3g/m 2 , its thermal conductivity can only reach 166 and 140W/m ⁇ K respectively.
  • the thermally conductive lithium ion separator provided by the present invention adopts the technical idea of mixing large particles with small particles, and the inorganic particles are easier to disperse in the slurry preparation, so that the inorganic particles are distributed on the base film when the subsequent slurry coating It is more uniform, and solves the technical defects of the conventional technology such as high difficulty of dispersion after mixing with small particles, easy agglomeration, and lack of heat resistance effect with large particles.
  • the thermally conductive lithium-ion diaphragm provided by the present invention uses aluminum nitride with a large particle size to give full play to its thermal conductivity, so that the diaphragm exhibits better thermal conductivity inside the battery; the size of aluminum nitride particles is larger than that of ceramic particles. Larger, so that more aluminum nitride is exposed on the surface of the base film. Based on its excellent thermal conductivity, the heat transfer flux of the separator is greatly increased, which is conducive to the smooth conduction of heat inside the battery from the positive and negative plates to the tabs. .
  • the thermally conductive lithium-ion diaphragm provided by the present invention adopts a base film prepared from high-molecular-weight PE particles, which has better physical and chemical properties, improves the energy density of the battery, and achieves good liquid absorption performance by controlling the porosity of the diaphragm And lower internal resistance will help to improve the electrochemical performance of the battery.
  • the thermally conductive lithium ion separator provided by the present invention contains trace elements such as Ca, Si, Fe, etc., and the prepared separator within the content range can prevent micro-short circuit inside the battery.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Inorganic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Cell Separators (AREA)

Abstract

本发明公开了一种导热锂离子隔膜及制备方法，导热性隔膜包括湿法基膜和涂层两部分，本发明提供的涂层包括陶瓷颗粒和氮化铝无机颗粒，通过有机粘结剂混合粘结。相对于单一的氧化铝或者勃姆石陶瓷涂层，在此基础上引入氮化铝颗粒极大的改善了锂离子隔膜的热传导性能，通过控制氮化铝的量可以提高导热性能以及隔膜综合性能，最终制备的导热隔膜导热性能以及电池安全性能等其它电化学性能得到有效提升。

Description

一种导热锂离子隔膜及其制备方法 技术领域
本申请属于隔膜领域，具体涉及到一种采用导热颗粒混合陶瓷涂层的电池隔膜制备方法。
背景技术
随着新能源车的快速发展，锂离子电池的广泛应用正在加速，为了能够完全替代传统燃油汽车，锂离子电池需要解决续航里程和充电时长的问题，而锂离子电池能量密度、容量和功率密度的提升，带动快充技术亦成为锂离子电池市场的重要发展方向。锂离子电池快速充放电的过程中，将在内部产生大量的热且难以均匀、有效地散去，从而引起衰减加速以及其他安全问题，阻碍新能源车发展步伐，使得内部散热问题正成为一个凸出的安全隐患。
从材料角度去思考解决方案，锂离子电池主要包括正极、负极、隔膜、电解液四大材料，其中导热性最差的即为隔膜元件。传统的耐热隔膜材料大多采用氧化铝涂层，可以很好改善隔膜的热稳定性和润湿性，基本可以满足现有锂离子电池需求。但传统隔膜在适应快充环境，快速导热、散热等方面幷不能得到预期的优异改进，且水分普遍较高，出现顾此失彼的问题。传统隔膜导热性能比较差这一问题一直被忽视，关于导热隔膜的研究也比较少。此外，也出现在涂层中加入氮化铝的研究，这种基于氮化铝本身的高导热性而采取与其它陶瓷材料混涂的工艺，仅在提高耐热隔膜收缩率性能上具有凸出效果。因此，对导热隔膜进行研究，幷且开发一种高导热锂离子隔膜实属必要。
发明内容
本发明着重解决锂电池内部过量热量不能有效快速散去导致电池安全以及性能衰减等问题，开发了一种新型锂离子隔膜，并开创性的引入一种氮化铝涂层材料。
是以，本发明之一目的系提供一种导热锂离子隔膜，其包括：一基膜及 一导热涂层，设置于所述基膜之一表面上，其中，所述导热涂层包括无机颗粒、陶瓷颗粒、氮化铝颗粒、机粘结剂或其组合；其中，所述无机颗粒包含陶瓷颗粒、氮化铝颗粒，所述陶瓷颗粒及所述氮化铝颗粒均匀分布于所述基膜上，其中，以所述基膜之一表面为水平基准，所述氮化铝颗粒较相邻之所述陶瓷颗粒高1～3μm，所述氮化铝颗粒以单位面积重量1.5～3g/m 2设置于所述基膜上。
如上所述导热锂离子隔膜，其中，所述陶瓷颗粒平均粒径介于0.6-1.5μm，所述氮化铝平均粒径介于4-6μm。
如上所述导热锂离子隔膜，其中，所述陶瓷颗粒与氮化铝重量比例介于5：1～1：1.2之间。
如上所述导热锂离子隔膜，其中，所述氮化铝颗粒比表面积小于所述陶瓷颗粒比表面积。
如上所述导热锂离子隔膜，其中，所述陶瓷颗粒比表面积为3-9m 2/g，所述氮化铝颗粒比表面积为2-5m 2/g。
如上所述导热锂离子隔膜，其中，所述导热涂层进一步包括有机溶剂，所述有机溶剂占所述无机颗粒的干重比例介于3％-5％。
如上所述导热锂离子隔膜，其中，所述陶瓷颗粒导热系数在25-35W/m·K，所述氮化铝颗粒导热系数在250-320W/m·K。
如上所述导热锂离子隔膜，其中，所述基膜厚度选用范围5-12μm，孔隙率在45％-55％。
如上所述导热锂离子隔膜，其中，所述基膜包含PE材质基膜，所述PE材质基膜系由高分子量PE颗粒所组成，所述高分子量PE颗粒之分子量介于110-310万。
如上所述导热锂离子隔膜，其中，所述氮化铝颗粒Ca含量≤100ppm，Si含量≤10ppm，Fe含量≤10ppm。
如上所述导热锂离子隔膜，其中，所述陶瓷颗粒包括氧化铝、勃姆石或其组合。
本发明之另一目的系提供一种导热锂离子隔膜的制备方法，包括步骤：1)提供一基膜；2)混合陶瓷颗粒和氮化铝以获得一混合浆料；及3)将所述混合浆料涂布于所述基膜之至少一个面上以获得该导热锂离子膈膜，其中，所述混合浆料以线棒或凹版辊方式以一涂布速度进行涂布，所述涂布速度介于50m/min-80m/min，
如上所述导热锂离子隔膜的制备方法，其中，该方法进一步包括步骤4)干燥所述锂离子膈膜，干燥温度介在70℃-100℃。
本发明之又一目的系提供一种锂离子电池隔膜，其包括如上所述方法制备之导热锂离子隔膜。
本发明所提供之锂离子电池膈膜具备以下优异的特性：
1、本发明所提供之导热锂离子隔膜暴露了更多的氮化铝，基于氮化铝本身优异的导热系数，大幅度的缩短隔膜的传热通路，有利于电池内部过多的热量通过导热隔膜的作用，使得热量由正负极片传导到极耳的路径更加顺畅。
2、本发明所提供之导热锂离子膈膜采用高分子量PE颗粒制备之基膜，其具备较佳的物化性能，提升了电池能量密度，并藉由隔膜孔隙率的控制达到了良好的吸液性能以及更低的内阻，有利于电池电化学性能的提升。
3、本发明所提供之导热锂离子隔膜，所采用的涂层材料具有含微量Ca、Si、Fe等元素，其含量范围内，所制备之隔膜得以防止电池内部产生微短路。
4、本发明所提供之导热锂离子隔膜之制备方法，采用大颗粒混小颗粒之技术思想，收获了浆料制备中颗粒较易分散的效果，使得后续浆料涂布中颗粒在基膜上分布得更加均匀，解决了习知技术中采用小颗粒混合后分散难度高、易团聚，以及采用大颗粒起不到耐热效果等技术缺陷；另一方面，选用更大粒径的氮化铝充分发挥了氮化铝的导热性能，使隔膜在电池内部展现更佳的热传导性能。
附图说明
图1为本发明提供的导热锂离子隔膜制备以及构成简图。
图2为本发明提供的导热锂离子隔膜SEM图。
图3为本发明提供之导热锂离子隔膜制备方法其具体流程图。
具体实施方式
随着锂离子电池的快速发展，安全问题一直排在首位，隔膜在电池中的功能主要作用就是防止正负极短路，允许锂离子在隔膜中来回穿梭。在保障电池的安全性能中起着重要作用，然而内部热效应导致温度无法很快通过隔膜往外扩散，大大增加了电池的安全风险。
对于传统隔膜导热性差的缺陷，本发明提出一种新的导热涂层，主要是在传统氧化铝或者勃姆石涂层中增加导热性能更好的氮化铝颗粒，实现优势互补，另外，较好的导热性能也提高到了导热锂离子隔膜的耐热性能，使得电池安全性能大大增加。
本发明提供的导热锂离子隔膜，具有较好的导热性、耐热性、较低的水分以及内阻。为了进一步说明所提供导热锂离子隔膜性能和制备方法，下面结合特定的具体实施例和附图对本发明优势作详细阐述。
一种导热锂离子隔膜，其包括一基膜1及一导热涂层，设置于所述基膜1之一表面上，其中，所述导热涂层包括无机颗粒、机粘结剂4或其组合；其中，所述无机颗粒包含陶瓷颗粒2、氮化铝颗粒3，所述陶瓷颗粒及所述氮化铝颗粒均匀分布于所述基膜上，其中，以所述基膜之一表面为水平基准，所述氮化铝颗粒较相邻之所述陶瓷颗粒高1～3μm，所述氮化铝颗粒以单位面积重量1.5～3g/m 2设置于所述基膜上。
请参阅图1，其系本发明提供之导热锂离子隔膜其构成简图；具体来说，由图1可以看到，以所述基模1之任一表面为水平基准，氮化铝颗粒3比陶瓷颗粒2涂层高1-3μm，基于氮化铝本身优异的导热性能，所述氮化铝颗粒3于所述基膜1单位面积重量为1.5-3g/m 2之间，由此得到的导热锂离子隔膜暴露更多的氮化铝，缩短隔膜的传热通路，有利于内 部过多的热量通过导热隔膜的作用，使得热量在正负极极片传导到极耳更加顺畅，氮化铝颗粒3可以为任意形貌，能够列举的有椭球形、棒状、块状、球形、片状，优选氮化铝颗粒2为椭球形貌；所述陶瓷颗粒2涂层涂层厚度可以为2-5μm，优选3μm；考量无机颗粒尺寸大小，若涂层厚度太薄，将降低涂层一致性，在实际工艺上并不好控制，若涂层过厚，将增加隔膜的厚度及重量，对电池性能不利；请参阅图2，其系扫描式电子显微镜(Scanning Electron Microscopy,SEM)放大图，呈现本发明一示例中导热涂层之表面构造，可以清楚看到，陶瓷颗粒和氮化铝的形貌及分布，尺寸大小不一之无机颗粒均匀的分布于基膜上，若只是单纯将氮化铝颗粒与陶瓷颗粒混合，幷不能得到改善导热性的效果；其中，所述陶瓷颗粒平均粒径介于0.6-1.5μm，所述氮化铝平均粒径介于4-6μm。
具体来说，所述导热涂层由涂布浆料经过涂布机涂布获得，其中所述涂布浆料固体含量为28％-38％，包含水、无机颗粒、有机溶剂，水与无机颗粒的比例在1.5：1～2.5：1之间；在一些实例中，所述无机颗粒包括陶瓷颗粒、氮化铝颗粒，所述无机颗粒系陶瓷颗粒及氮化铝颗粒按照一定比例混合而成，其中，陶瓷颗粒与氮化铝的比例在5：1～1：1.2之间，有机溶剂占无机颗粒的干重比例介于3％-5％；优选地，所述陶瓷颗粒包括氧化铝、勃姆石或其组合。
在一些实例中，所述氮化铝颗粒中Ca含量≤100ppm，Si含量≤10ppm，Fe含量≤10ppm；氮化铝颗粒中，金属异物含量小，可防止造成电池内部微短路发生，并提升电池内部电化学性能以及安全性能。
在一些较佳实例中，所述陶瓷颗粒之导热系数在25-35W/m·K，氮化铝颗粒导热系数在250-320W/m·K；传统氧化铝涂层材料不能满足锂离子隔膜高导热的要求，氮化铝的引入使得隔膜导热性能大大增加；传统涂布膜导热系数在10-30W/m·K之间，本发明提供的导热锂离子隔膜其导热系数在100-210W/m·K之间。导热系数的提高，可以加快电池内部 热量通过隔膜向极片往外扩散速度，使电池安全性能大大提高。
在一些实例中，所述陶瓷颗粒平均粒径D50在0.6-1.5μm，所述氮化铝颗粒平均粒径D50在4-6μm，其中所述氮化铝颗粒比表面积小于所述陶瓷颗粒比表面积；更具体地，陶瓷颗粒比表面积在3-9m 2/g，氮化铝比表面积在2-5m 2/g；较低比表面积氮化铝可以降低颗粒表面能(Surface energy)，减少团聚，有利于后续在涂布浆料中发挥更好的分散性能。
在另一些实例中，所述基膜系采用高分子量PE颗粒，分子量在110-310万；所述基膜厚度选用范围5-12μm，优选厚度为9μm，孔隙率在45％-55％，优选孔隙率50％。高孔隙率减少了隔膜透气性，从而降低了隔膜内阻，並有利于提高电池电化学性能。
在上述实施例中，所述有机溶剂包含粘结剂、润湿剂；所述粘结剂选自水溶剂型或乳液型中的一种或者多种组合，粘结剂主要系丙烯酸树脂类或丙烯酸共聚体，系选自丙烯酸树脂类、PMMA、PVDF、聚乙烯醇中的一种或多种组合，其结构中包含羧基、羟基等改性基团；通过改性基团可以按照需求增加性能，扩充了导热锂离子隔膜的应用性；更具体地，所述粘结剂与润湿剂比例介于100：1～50：1之间。
本发明之另一实施方式系一种导热锂离子隔膜之制备方法，主要分为湿法基膜提供—涂布浆料制备—浆料涂布三个步骤，更具体地，请参阅图3，其系说明本实施方式制备方法之具体流程图，该方法包括步骤：
1)提供一基膜；
2)混合陶瓷颗粒和氮化铝以获得一混合浆料；及
3)将所述混合浆料涂布于所述基膜之至少一个面上以获得该导热锂离子膈膜，其中，所述混合浆料以线棒或凹版辊方式以一涂布速度进行涂布，所述涂布速度介于50m/min-80m/min。
在一些较佳实例中，该方法进一步包括步骤：
4)干燥所述锂离子膈膜，干燥温度介在70℃-100℃；具体而言，所 述混合浆料在涂布后获得所述锂离子隔膜，其转移至至少包括两节烘箱中进行干燥，烘箱温度控制在70℃-100℃，优选温度为85℃。
测试方法
厚度
样品厚度通过MahrMillimar测厚仪来测量，测试条件：A)测量表面平整；B)测量表面直径:φ12mm；C)测量面载荷:0.75N。
氮化铝颗粒与陶瓷涂层高度差
通过场发射电子扫描显微镜SEM拍导热锂离子隔膜的截面形貌，测试出出高度。
氮化铝颗粒在基膜单位面积重量
根据实际添加比例来推算，例如实际配方中氮化铝：陶瓷颗粒为X，那么实际可以测出导热膜的单位面积重量为Y1，对应基膜为单位面积重量为Y2，则氮化铝颗粒在基膜单位面积重量为(Y1-Y2)·(X/1+X)，设备采用梅特勒托莱多XS205电子天平来测量，精度0.1mg。
氮化铝颗粒杂质含量测定
利用电感耦合等离子体发射光谱仪ICP-OES-5110VDV，样品测试前在温度23℃±2℃和湿度50％±10％下调节时间不少于4h，测试条件：RF功率：1300W，等离子气流量：10L/min，辅助气流量：0.3L/min，雾化器流量：0.7L/min，观测高度：15mm。
D50
采用欧美克粒度仪LS-POP(9)测量，将少量待测样品放入仪器水槽内，按照选定测试条件得到仪器检测数据。测试条件：选定待测材料折射率：1.8，分散介质折射率：1.33，遮光比：6-9，测样次数：3次。
比表面积
比表面积测定仪，按照GB/T 19587-2004气体吸附BET法测定固态物质比表面积。
导热系数
通过导热仪测量，将一定厚度的样品置于上下两个平板间，对样品施加一定的热流量和压力，使用热流传感器测量通过样品的热流、测试样品的厚度、热板/冷板间的温度梯度，然后得出不同厚度下对应的热阻数据作直线拟合得出样品的导热系数。
水分
采用卡尔费休水分测定仪，测样条件：称取样品质量为0.1g-0.15g，测定温度180℃，测试时间为5分钟。
热收缩
将待测样品裁剪成80mm x 80mm大小，标记MD和TD方向，以150℃烘烤1小时，取出后采用光学投影仪测量MD/TD方向收缩后长度，具体收缩率计算式如下：
横向收缩率MD：
Figure PCTCN2022100730-appb-000001
纵向收缩率TD：
Figure PCTCN2022100730-appb-000002
须说明的是，上述计算式中，M 0,T 0—初始长度，单位mm；M,T—最终长度，单位为mm。
内阻
截取与电阻测试模具相匹配的隔膜5块，将隔膜放入浓度1mol/L的六氟磷酸锂(LiPF6),碳酸乙烯酯(EC)中，保持密封浸泡。将浸泡后的隔膜依次放入1层隔膜，测试交流阻抗电阻，再放入层测试其交流阻抗，直至放入5层，分别测试出5个交流电阻。以隔膜层数为横坐标，隔膜电阻为纵坐标，求出曲线的斜率和线性拟合度，当线性拟合度大于0.99时，该斜率为隔膜阻抗。设备采用Solatron analytical 1400 CellTest System自主设计测试装置。
以下透过数个示例性实施例进一步说明本发明导热锂离子隔膜制备方法其技术方案及其技术功效。
实施例1
提供基膜：于本实施例中，所提供的PE基膜系按照常规湿法工艺制备，采用该工艺所得的基膜具有高孔隙率、孔径均匀、机械强度高、安全性好以及可以制备厚度超薄产品；于本实施例中，基膜厚度优选为9μm、孔隙率50％，该厚度基膜制备工艺成熟，隔膜一致性佳，孔隙率可以任意调控，并具备突出的机械性能及安全性能。
涂布浆料的制备：水和羧甲基纤维素(Carboxymethyl Cellulose，CMC)以比例在100：1～100：5范围内混合，并以机械搅拌水和CMC获得透明澄清CMC溶液。接着，将陶瓷颗粒和氮化铝颗粒以重量比为6：1混合，分批加入CMC溶液中，然后匀速搅拌，搅拌时间至少在30分钟，以使颗粒在CMC溶液中充分混匀；随后将该半成品浆料通过研磨，使浆料中颗粒充分分散后，再加入定量的有机溶剂，包括粘结剂和润湿剂；有机溶剂与无机颗粒干重比2.5％。最后，以一定的速度搅拌使有机溶剂与半成品浆料均匀混合形成成品涂布浆料。
浆料涂布：通过线棒方式或者凹版辊使浆料涂布于前述基膜上，本实施例中，陶瓷涂层厚度3μm，涂布浆料至少涂布在基膜的一个面上，涂布速度在80m/min，涂布烘箱温度在85℃；前述涂布烘箱具有2节，每节温度可以按照实际情况进行调控。
表1
Figure PCTCN2022100730-appb-000003
Figure PCTCN2022100730-appb-000004
请参阅表2，实施例1所制备之导热锂离子隔膜经前述测试方法后，测得其导热系数为170W/m·K、热收缩系数分别为6％(MD)、6％(TD)，水分为721ppm，内阻为1.37Ω*cm 2。
表2
Figure PCTCN2022100730-appb-000005
实施例2
制备方法步骤同实施例1，请参阅表1，惟以下制备条件有所不同：
有机溶剂与无机颗粒干重比5.5％。
陶瓷颗粒与氮化铝重量比1:1.5。
氮化铝颗粒D50为4μm、单位面积重量为3g/m 2。
陶瓷颗粒D50为0.6μm、比表面积为10m 2/g。
实施例2所制备之导热锂离子隔膜，其导热系数为175W/m·K、热收缩系数分别为6％(MD)、5％(TD)，水分为679ppm，内阻为1.38Ω*cm 2。
实施例3
制备方法步骤同实施例2，请参阅表1，惟以下制备条件有所不同：
氮化铝颗粒D50为6μm、单位面积重量为2g/m 2。
陶瓷颗粒D50为1.5μm、比表面积为3m 2/g。
实施例3所制备之导热锂离子隔膜，其导热系数为183W/m·K、热收 缩系数分别为6％(MD)、5％(TD)，水分为664ppm，内阻为1.36Ω*cm 2。
实施例4
制备方法步骤同实施例1，请参阅表1，惟以下制备条件有所不同：
有机溶剂与无机颗粒干重比2.5％。
陶瓷颗粒与氮化铝重量比5:1。
氮化铝颗粒含Ca ppm≤100、Si ppm≤10、Fe ppm≤10；D50为5μm；比表面积为5m 2/g、单位面积重量为1.7g/m 2。
陶瓷颗粒D50为0.8μm、比表面积为9m 2/g。
实施例4所制备之导热锂离子隔膜，其导热系数为191W/m·K、热收缩系数分别为6％(MD)、4％(TD)，水分为658ppm，内阻为1.33Ω*cm 2。
实施例5
制备方法步骤同实施例1，请参阅表1，惟以下制备条件有所不同：
有机溶剂与无机颗粒干重比5.5％。
陶瓷颗粒与氮化铝重量比2:1。
氮化铝颗粒含Ca ppm≤100、Si ppm≤10、Fe ppm≤10；D50为5μm；比表面积为4m 2/g、单位面积重量为2g/m 2。
陶瓷颗粒D50为1μm、比表面积为4m 2/g。
实施例5所制备之导热锂离子隔膜，其导热系数为194W/m·K、热收缩系数分别为5％(MD)、5％(TD)，水分为645ppm，内阻为1.35Ω*cm 2。
实施例6
制备方法步骤同实施例1，请参阅表1，惟以下制备条件有所不同：
有机溶剂与无机颗粒干重比3.0％。
陶瓷颗粒与氮化铝重量比3:1。
氮化铝颗粒含Ca ppm≤100、Si ppm≤10、Fe ppm≤10；D50为5μm；比表面积为4m 2/g、单位面积重量为1.9g/m 2。
陶瓷颗粒D50为0.8μm、比表面积为8m 2/g。
实施例6所制备之导热锂离子隔膜，其导热系数为200W/m·K、热收 缩系数分别为5％(MD)、4％(TD)，水分为633ppm，内阻为1.36Ω*cm 2。
实施例7
制备方法步骤同实施例1，请参阅表1，惟以下制备条件有所不同：
有机溶剂与无机颗粒干重比3.5％。
陶瓷颗粒与氮化铝重量比2:1。
氮化铝颗粒含Ca ppm≤100、Si ppm≤10、Fe ppm≤10；D50为5μm；比表面积为4m 2/g、单位面积重量为2g/m 2。
陶瓷颗粒D50为0.8μm、比表面积为5m 2/g。
实施例7所制备之导热锂离子隔膜，其导热系数为204W/m·K、热收缩系数分别为5％(MD)、3％(TD)，水分为620ppm，内阻为1.32Ω*cm 2。
实施例8
制备方法步骤同实施例1，请参阅表1，惟以下制备条件有所不同：
有机溶剂与无机颗粒干重比4.0％。
陶瓷颗粒与氮化铝重量比1:1。
氮化铝颗粒含Ca ppm≤100、Si ppm≤10、Fe ppm≤10；D50为5μm；比表面积为3m 2/g、单位面积重量为2.5g/m 2。
陶瓷颗粒D50为1.3μm、比表面积为7m 2/g。
实施例8所制备之导热锂离子隔膜，其导热系数为210W/m·K、热收缩系数分别为4％(MD)、3％(TD)，水分为600ppm，内阻为1.28Ω*cm 2。
实施例9
制备方法步骤同实施例1，请参阅表1，惟以下制备条件有所不同：
有机溶剂与无机颗粒干重比3.5％。
陶瓷颗粒与氮化铝重量比1:1.2。
氮化铝颗粒含Ca ppm≤100、Si ppm≤10、Fe ppm≤10；D50为5μm；比表面积为4m 2/g、单位面积重量为1.9g/m 2。
陶瓷颗粒D50为0.8μm、比表面积为5m 2/g。
实施例9所制备之导热锂离子隔膜，其导热系数为204W/m·K、热收 缩系数分别为5％(MD)、4％(TD)，水分为618ppm，内阻为1.21Ω*cm 2。
对比例1
制备方法步骤同实施例1，请参阅表1，惟以下制备条件有所不同：
涂层厚度为5μm。
有机溶剂与无机颗粒干重比4.0％。
陶瓷颗粒与氮化铝重量比1:1.5。
氮化铝颗粒D50为8μm；比表面积为6m 2/g、单位面积重量为3g/m 2。
陶瓷颗粒D50为2μm、比表面积为10m 2/g。
对比例1所制备之导热锂离子隔膜，其导热系数为162W/m·K、热收缩系数分别为7％(MD)、5％(TD)，水分为740ppm，内阻为1.30Ω*cm 2。
对比例2
制备方法步骤同实施例1，请参阅表1，惟以下制备条件有所不同：
有机溶剂与无机颗粒干重比4.0％。
陶瓷颗粒与氮化铝重量比1:1.5。
氮化铝颗粒D50为8μm；比表面积为6m 2/g、单位面积重量为3.2g/m 2。
陶瓷颗粒D50为8μm、比表面积为6m 2/g。
对比例2所制备之导热锂离子隔膜，其导热系数为166W/m·K、热收缩系数分别为7％(MD)、6％(TD)，水分为640ppm，内阻为1.20Ω*cm 2。
对比例3
制备方法步骤同实施例1，请参阅表1，惟以下制备条件有所不同：
有机溶剂与无机颗粒干重比4.0％。
陶瓷颗粒与氮化铝重量比1:2。
氮化铝颗粒D50为8μm；比表面积为6m 2/g、单位面积重量为4g/m 2。
陶瓷颗粒D50为2μm、比表面积为10m 2/g。
对比例3所制备之导热锂离子隔膜，其导热系数为140W/m·K、热收缩系数分别为5％(MD)、5％(TD)，水分为740ppm，内阻为1.41Ω*cm 2。
对比例4
制备方法步骤同实施例1，请参阅表1，惟以下制备条件有所不同：
有机溶剂与无机颗粒干重比4.0％。
陶瓷颗粒与氮化铝重量比1:2。
氮化铝颗粒D50为5μm；比表面积为4m 2/g、单位面积重量为4g/m 2。
陶瓷颗粒D50为0.8μm、比表面积为10m 2/g。
对比例4所制备之导热锂离子隔膜，其导热系数为160W/m·K、热收缩系数分别为6％(MD)、6％(TD)，水分为612ppm，内阻为1.29Ω*cm 2。
请一并参阅表1及表2，由前述实施例与对比例可知，导热锂离子隔膜所含水份主要和氮化铝颗粒含量有关系，氮化铝不易吸水，含量占比越多，会导致水分降低；此外，随着氮化铝的增加热收缩有着减小的趋势，氮化铝增加热收缩并没有减小，反而增大；这是由于氮化铝颗粒较大，当到达一定量，在基膜上的堆积密度反而变小，结果造成热收缩增加；氮化铝高度在1-3μm之间所带来导热性能的提升，同时热收缩相比也更小；最后，导热锂离子隔膜内阻和氮化铝占比成反比关系，主要系由于氮化铝可以提高涂层孔隙率，使得锂离子更容易通过。
另一方面，氮化铝单位面积重量亦影响了导热锂离子隔膜所展现的导热性能，例如实施例1与对比例2-3所示，实施例1之氮化铝单为面积重量为1.5g/m 2，其导热系数仅170W/m·K，其导热性并无法满足高导热的需求；在于对比例2-3当中，氮化铝单位面积重量分别为3.2、4g/m 2均高于3g/m 2，其导热系数亦仅分别达到166、140W/m·K。
本发明所提供之锂离子电池膈膜具备以下优异的特性：
1、本发明所提供之导热锂离子隔膜，采用了大颗粒混小颗粒之技术思想，在浆料制备中无机颗粒较易分散，得使后续浆料涂布时，无机颗粒在基膜上分布更加均匀，解决了习知技术中采用小颗粒混合后分散难度高、易团聚，以及采用大颗粒起不到耐热效果等技术缺陷。
2、本发明所提供之导热锂离子隔膜，选用大粒径的氮化铝，更充分地发挥其导热性能，使隔膜在电池内部展现更佳的热传导性能；氮化铝 颗粒较陶瓷颗粒尺寸为大，使得基膜表面得暴露更多的氮化铝，基于其本身优异的导热系数，大幅度的增加隔膜的传热通量，利于电池内部的热量更顺畅地由正负极片传导至极耳。
3、本发明所提供之导热锂离子膈膜采用高分子量PE颗粒制备之基膜，其具备较佳的物化性能，提升了电池能量密度，并藉由控制隔膜孔隙率来达到了良好吸液性能及更低的内阻，将有利于提升电池之电化学性能。
4、本发明所提供之导热锂离子隔膜，涂层材料中含有微量Ca、Si、Fe等元素，并其含量范围内所制备之隔膜得以防止电池内部产生微短路。
以上实施例内容仅为对本发明提出的导热锂离子隔膜性能和制备方法的示例性说明，并没有对本发明有任何制约之处，对于该领域的任何技术研究人员，在不脱离本发明的思想和思维框架下，对于本发明作出适当的简单修改或方案调整，都应当属本申请发明权利保护范围。

Claims (13)

  1. 一种导热锂离子隔膜，其包括：
    一基膜；及
    一导热涂层，设置于所述基膜之一表面上，其中，所述导热涂层包括无机颗粒、机粘结剂或其组合；其中，所述无机颗粒包含陶瓷颗粒、氮化铝颗粒或其组合，所述陶瓷颗粒及所述氮化铝颗粒均匀分布于所述基膜上，其中，以所述基膜之一表面为水平基准，所述氮化铝颗粒较相邻之所述陶瓷颗粒高1～3μm，所述氮化铝颗粒以单位面积重量1.5～3g/m 2设置于所述基膜上。
  2. 根据权利要求1所述导热锂离子隔膜，其特征在于，所述氮化铝颗粒比表面积小于所述陶瓷颗粒比表面积；其中，所述陶瓷颗粒比表面积为3-9m 2/g，所述氮化铝颗粒比表面积为2-5m 2/g。
  3. 根据权利要求1所述导热锂离子隔膜，其特征在于，所述陶瓷颗粒D50平均粒径介于0.6-1.5μm，所述氮化铝D50平均粒径介于4-6μm。
  4. 根据权利要求1所述导热锂离子隔膜，其特征在于，所述陶瓷颗粒与氮化铝重量比例介于5：1～1：1.2之间。
  5. 根据权利要求1所述导热锂离子隔膜，其特征在于，所述导热涂层进一步包括有机溶剂，所述有机溶剂占所述无机颗粒的干重比例介于3％-5％。
  6. 根据权利要求1所述导热锂离子隔膜，其特征在于，所述陶瓷颗粒导热系数在25-35W/m·K，所述氮化铝颗粒导热系数在250-320W/m·K。
  7. 根据权利要求1所述导热锂离子膈膜，其特征在于，所述基膜厚度选用范围5-12μm，孔隙率在45％-55％。
  8. 根据权利要求1所述导热锂离子膈膜，其特征在于，所述基膜包含PE材质基膜，其系由高分子量PE颗粒所组成，所述高分子量PE颗粒之分子量介于110-310万。
  9. 根据权利要求1-8任一项所述导热锂离子隔膜，其特征在于，所述氮化铝颗粒Ca含量≤100ppm，Si含量≤10ppm，Fe含量≤10ppm。
  10. 根据权利要求8所述导热锂离子隔膜，其特征在于，所述陶瓷颗粒包括氧化铝、勃姆石或其组合。
  11. 一种导热锂离子隔膜的制备方法，包括步骤：
    1)提供一基膜；
    2)混合陶瓷颗粒和氮化铝以获得一混合浆料；及
    3)将所述混合浆料涂布于所述基膜之至少一个面上以获得该导热锂离子膈膜，其中，所述混合浆料以线棒或凹版辊方式以一涂布速度进行涂布，所述涂布速度介于50m/min-80m/min。
  12. 如权利要求11所述之方法，其中，该方法进一步包括步骤4)干燥所述锂离子膈膜，干燥温度介在70℃-100℃。
  13. 一种锂离子电池隔膜，包括由权利要求11或12任一项所述方法制备之锂离子电池隔膜。
PCT/CN2022/100730 2021-12-01 2022-06-23 一种导热锂离子隔膜及其制备方法 WO2023098044A1 (zh)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CN202111454376.6 2021-12-01
CN202111454376.6A CN114142156A (zh) 2021-12-01 2021-12-01 一种导热锂离子隔膜及其制备方法

Publications (1)

Publication Number Publication Date
WO2023098044A1 true WO2023098044A1 (zh) 2023-06-08

Family

ID=80386715

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/CN2022/100730 WO2023098044A1 (zh) 2021-12-01 2022-06-23 一种导热锂离子隔膜及其制备方法

Country Status (2)

Country Link
CN (1) CN114142156A (zh)
WO (1) WO2023098044A1 (zh)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114142156A (zh) * 2021-12-01 2022-03-04 上海恩捷新材料科技有限公司 一种导热锂离子隔膜及其制备方法
CN114709565B (zh) * 2022-06-07 2022-09-02 中材锂膜(宁乡)有限公司 有机/无机复合层多孔隔膜、其制备方法及电化学装置
KR20240024220A (ko) * 2022-08-12 2024-02-23 컨템포러리 엠퍼렉스 테크놀로지 씨오., 리미티드 분리막, 그 제조 방법, 이를 사용한 이차 전지, 전지 모듈, 전지팩 및 전기 장치

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102437302A (zh) * 2011-11-25 2012-05-02 东莞市比比克电子科技有限公司 一种锂离子电池隔膜及高温热稳定型锂离子电池
CN103811699A (zh) * 2012-11-08 2014-05-21 深圳市崧鼎实业有限公司 一种锂离子二次电池用隔离膜及其制备方法
US20160149188A1 (en) * 2014-11-21 2016-05-26 Samsung Sdi Co., Ltd. Separator for rechargeable lithium battery and rechargeable lithium battery including the same
CN106935778A (zh) * 2017-03-08 2017-07-07 东莞市赛普克电子科技有限公司 一种陶瓷隔膜及其制备方法
CN207938697U (zh) * 2018-01-22 2018-10-02 东莞市赛普克电子科技有限公司 一种带有颜色标识涂层的陶瓷隔膜
CN111742425A (zh) * 2018-11-05 2020-10-02 株式会社Lg化学 用于电化学装置的隔板和包含该隔板的电化学装置
CN114142156A (zh) * 2021-12-01 2022-03-04 上海恩捷新材料科技有限公司 一种导热锂离子隔膜及其制备方法

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3573137B1 (en) * 2013-03-19 2020-12-23 Murata Manufacturing Co., Ltd. Separator, battery, battery pack, electronic apparatus, electric vehicle, power storage device, and power system
CN105247703B (zh) * 2013-04-29 2019-09-03 奥普图多特公司 具有增加的热导率的纳米多孔复合分隔物
KR101748640B1 (ko) * 2013-10-22 2017-06-19 주식회사 엘지화학 유기-무기 복합 다공성 막, 이를 포함하는 세퍼레이터 및 전극구조체
CN107799696A (zh) * 2016-08-29 2018-03-13 比亚迪股份有限公司 一种锂离子电池隔膜及其制备方法和锂离子电池
CN106784529A (zh) * 2016-12-27 2017-05-31 深圳中兴创新材料技术有限公司 一种锂离子电池隔膜及其制备方法

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102437302A (zh) * 2011-11-25 2012-05-02 东莞市比比克电子科技有限公司 一种锂离子电池隔膜及高温热稳定型锂离子电池
CN103811699A (zh) * 2012-11-08 2014-05-21 深圳市崧鼎实业有限公司 一种锂离子二次电池用隔离膜及其制备方法
US20160149188A1 (en) * 2014-11-21 2016-05-26 Samsung Sdi Co., Ltd. Separator for rechargeable lithium battery and rechargeable lithium battery including the same
CN106935778A (zh) * 2017-03-08 2017-07-07 东莞市赛普克电子科技有限公司 一种陶瓷隔膜及其制备方法
CN207938697U (zh) * 2018-01-22 2018-10-02 东莞市赛普克电子科技有限公司 一种带有颜色标识涂层的陶瓷隔膜
CN111742425A (zh) * 2018-11-05 2020-10-02 株式会社Lg化学 用于电化学装置的隔板和包含该隔板的电化学装置
CN114142156A (zh) * 2021-12-01 2022-03-04 上海恩捷新材料科技有限公司 一种导热锂离子隔膜及其制备方法

Also Published As

Publication number Publication date
CN114142156A (zh) 2022-03-04

Similar Documents

Publication Publication Date Title
WO2023098044A1 (zh) 一种导热锂离子隔膜及其制备方法
WO2022227345A1 (zh) 一种复合隔膜及其制备方法和用途
CN105932209B (zh) 一种作为锂离子电池用的陶瓷涂覆隔膜及其制备方法
Yu et al. A newly-developed heat-resistance polyimide microsphere coating to enhance the thermal stability of commercial polyolefin separators for advanced lithium-ion battery
CN105762317A (zh) 一种水溶性聚合物辅助的无机复合隔膜的制备方法
CN107978789B (zh) 一种聚合物导电纤维增韧的硫化物复合电解质
CN109616605B (zh) 一种锂离子电池隔膜及其制备方法
WO2019206283A1 (zh) 聚合物隔膜及其制备方法和应用以及锂离子电池
CN105070867A (zh) 复合隔膜、其制备方法及锂离子电池
WO2023155604A1 (zh) 复合隔膜及电化学装置
CN114759157B (zh) 一种负极极片及其制备方法、锂二次电池
WO2023046027A1 (zh) 锂离子电池电极及其制备方法与锂离子电池
WO2024008055A1 (zh) 一种多孔隔膜、其制备方法及电化学装置
Kim et al. Preparation of micro-porous gel polymer for lithium ion polymer battery
Mi et al. Electrode-supported thin α-alumina separators for lithium-ion batteries
WO2023130683A1 (zh) 非水电解液锂二次电池用隔膜及非水电解液锂二次电池
CN111725466B (zh) 一种功能化聚烯烃复合隔膜及其制备方法和应用
CN112072047B (zh) 一种溶胶涂层隔膜及其制备方法
CN113161692A (zh) 陶瓷涂层、陶瓷涂覆隔膜及其制备方法与应用
WO2021189339A1 (zh) 负极极片、电化学装置和电子装置
CN110828781B (zh) 一种正极板及其制备方法和用途
Chen et al. The fabrication of high-performance α-Al2O3 coated PE separator for lithium-ion batteries based on multiple hydrogen bonds
Zaidi et al. Polymer-free electrospun separator film comprising silica nanofibers and alumina nanoparticles for Li-ion full cell
WO2022067812A1 (zh) 混合正极材料、正极极片及制备方法、电池和装置
CN112838265B (zh) 一种薄型层状复合固态电解质膜及其制备方法与应用

Legal Events

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

Ref document number: 22899864

Country of ref document: EP

Kind code of ref document: A1