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WO2014073750A1 - Séparateur en tissu non-tissé complexe pour batterie secondaire et procédé de fabrication de celui-ci - Google Patents

Séparateur en tissu non-tissé complexe pour batterie secondaire et procédé de fabrication de celui-ci Download PDF

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Publication number
WO2014073750A1
WO2014073750A1 PCT/KR2013/001965 KR2013001965W WO2014073750A1 WO 2014073750 A1 WO2014073750 A1 WO 2014073750A1 KR 2013001965 W KR2013001965 W KR 2013001965W WO 2014073750 A1 WO2014073750 A1 WO 2014073750A1
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Prior art keywords
nonwoven fabric
pva
secondary battery
poly
nanofiber nonwoven
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English (en)
Korean (ko)
Inventor
김하철
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Fibrane Co Ltd
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Fibrane Co Ltd
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Priority claimed from KR20120126656A external-priority patent/KR101490890B1/ko
Priority claimed from KR20120148343A external-priority patent/KR101490883B1/ko
Application filed by Fibrane Co Ltd filed Critical Fibrane Co Ltd
Publication of WO2014073750A1 publication Critical patent/WO2014073750A1/fr
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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
    • 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
    • H01M50/429—Natural polymers
    • H01M50/4295—Natural cotton, cellulose or wood
    • 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
    • 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
    • H01M50/411—Organic material
    • H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
    • H01M50/426—Fluorocarbon polymers
    • 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
    • H01M50/429—Natural polymers
    • 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
    • H01M50/44—Fibrous 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
    • H01M50/494—Tensile strength
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present invention relates to a separator for a secondary battery and a method of manufacturing the same.
  • Lithium secondary batteries are widely used in mobile devices and IT devices due to the advantages of high energy density. Recently, researches for applying lithium secondary batteries to high-capacity high-power fields such as automotive batteries such as HEV, PHEV, EV, and power storage batteries Development is underway globally. However, lithium secondary batteries are constantly causing safety-related accidents such as explosions, causing doubts about safety when applying high-capacity high-power fields, and efforts are being made to drastically improve safety.
  • polyolefin-based separators exhibit extreme heat shrinkage at temperatures above 150 ° C. and have a low mechanical strength. Therefore, the development of new membrane material and nano ceramic coating technology for improving the fundamental thermal stability and mechanical stability of the polyolefin-based separator is emerging.
  • LG Chem a Korean company, has developed a composite membrane coated with ceramic particles on a polyolefin-based separator and is currently in mass production, and is currently applied to lithium secondary batteries installed in Avante LPI hybrid vehicles developed by Hyundai Motor. Motorola of the United States has applied for a number of patents in the field of using a porous membrane as a support, US Patent No. 5,681,357.
  • a cell is prepared by coating and drying a poly (vinylidene fluoride) solution on a polyethylene-based separator which is well known as Celgard, and then injecting an electrolyte solution and gelating at a high temperature.
  • a method of manufacturing a secondary battery is provided.
  • a technology for improving thermal shrinkage or lowering of mechanical strength at a temperature of 150 ° C. or higher by coating a functional material such as ceramic particles or polyvinylidene fluoride on an existing polyolefin-based separator has limitations on the adhesion and coating amount of the coating material. I have the same problem.
  • Existing polyolefin-based separators are hydrophobic and have a very smooth structure, so that the adhesion strength of coating materials is low, making it difficult to select coating materials and coating work. There is a risk of dropping and losing function.
  • the conventional polyolefin-based membrane has a pore size of about 0.5 ⁇ m or less and a porosity of about 40%, and as the amount of coating increases, the pore size and porosity decrease and eventually the membrane function is lost.
  • the heat resistant nonwoven fabric When the heat resistant nonwoven fabric is used as a separator, thermal stability and porosity of 60% or more are excellent.
  • thermal stability and porosity of 60% or more are excellent.
  • the pore size is about tens of ⁇ m compared to the polyolefin-based separator, there is a limit to apply directly to the lithium secondary battery separator.
  • a technique for controlling the pore size which is a disadvantage of the nonwoven separator by coating a functional material such as ceramic particles or polyvinylidene fluoride on the nonwoven fabric, has been introduced at home and abroad.
  • German ebonics has developed a composite separator coated with ceramic particles on a polyethylene terephthalate (PET) nonwoven fabric and is currently manufacturing prototypes.
  • Japan's Mitsubishi Chemical is developing a product in which ceramic particles are applied to a non-woven fabric made of aramid fibers, but there have been no commercialization cases.Asahi, Tonen and Japan's Celgard are also developing high-safety separators. have.
  • the present invention was derived to solve the above problems, the problem to be solved by the present invention is to provide a secondary battery separator having a desired pore size, porosity, tensile strength, air permeability, thermal characteristics and the like and a method of manufacturing the same. .
  • Separation method for a secondary battery comprises the step of forming a nanofiber nonwoven fabric using a polymer solution in which a polymer is dissolved, and coating a functional material on the nanofiber nonwoven fabric.
  • Separation method for a secondary battery may further comprise the step of pressing the nanofiber nonwoven fabric to control the physical properties of the nanofiber nonwoven fabric, pressing the nanofiber nonwoven fabric is the functional material It may be carried out after or before the coating step, and in other embodiments it may be carried out before and after respectively.
  • the polymer used in the manufacture of the nanofiber nonwoven fabric is 1) a polymer containing a hydroxyl group ( ⁇ OH group) in the molecular structure, such as cellulose derivative, chitin, chitosan, alginate, PVA (polyvinyl alcohol) having a degree of polymerization of 1,000 or less, 2) Poly sulfone (PSU), poly ether imide (PEI), 3) PVA with a degree of polymerization greater than 1,000, polyimide (PI), poly vinylidene fluoride (PVDF), poly acrylo nitrile (PAN), polyethylene oxide (PEO), PE ( It may be selected from the group consisting of poly ethylene), PP (poly propylene), PET (poly ethylene terephthalate), and mixtures thereof.
  • PVA polyvinyl alcohol
  • PSU Poly sulfone
  • PEI poly ether imide
  • PE polymer with a degree of polymerization greater than 1,000
  • PI polyimide
  • the functional material is PVA based on a degree of polymerization of more than 1,000, water-soluble PEO (polyethylene oxide), PVDF (poly vinylidene fluoride), water-soluble or water-dispersible polyester-polyol (PAN), polyacrylonitrile (PAN), PMMA It may be selected from the group consisting of (poly methyl methacrylate), and mixtures thereof.
  • Preparation of the nanofiber nonwoven fabric and the functional material of the PVA system is a fully hydrolyzed polyvinyl alcohol (PVA) of 98-99% saponification or partly hydrolyzed (85-89%) saponification. ) PVA.
  • the polymer solution used for the nanofiber nonwoven fabric or the polymer solution which is the functional material may contain a crosslinking agent.
  • the pressing step it may be performed at a pressing pressure of 245 Kgf / cm or less and a pressing temperature of 70 ° C. or less.
  • the nanofiber nonwoven fabric is electrospinning, melt spinning, electro-blowing, melt-blowing (composite spinning, split yarn), using the polymer solution, It may be produced by a spun-bonded, air laid, or wet laid method.
  • the nanofiber nonwoven fabric has a thickness of 10 to 100 ⁇ m, the nanofibers constituting the nanofiber nonwoven fabric may have a diameter of 100 to 3000nm.
  • the secondary battery separator according to an embodiment of the present invention is formed by coating a functional material on a nanofiber nonwoven fabric formed using a polymer solution.
  • the nanofiber nonwoven fabric may be pressed to control physical properties.
  • the pressing may be performed at a pressing pressure of 245 Kgf / cm or less and a pressing temperature of 70 ° C. or less.
  • the polymer is a polymer containing a hydroxyl group ( ⁇ OH group) in the molecular structure, such as cellulose derivative, chitin, chitosan, alginate, PVA (polyvinyl alcohol) having a degree of polymerization of 1,000 or less, 2) poly sulfone (PSU), PEI ( Poly ether imide), 3) PVA, polyimide (PI), poly vinylidene fluoride (PVDF), poly acrylo nitrile (PAN), polyethylene oxide (PEO), polyethylene (PE), poly (propylene) ), PET (polyethylene terephthalate), and may be selected from the group consisting of a mixture thereof.
  • PVA polyvinyl alcohol
  • PSU poly sulfone
  • PEI Poly ether imide
  • PVA polyimide
  • PVDF poly vinylidene fluoride
  • PAN poly acrylo nitrile
  • PET polyethylene terephthalate
  • PET polyethylene terephthalate
  • the functional material is PVA based on a degree of polymerization of more than 1,000, water-soluble PEO (polyethylene oxide), PVDF (poly vinylidene fluoride), water-soluble or water-dispersible polyester-polyol (PAN), polyacrylonitrile (PAN), PMMA It may be selected from the group consisting of (poly methyl methacrylate), and mixtures thereof.
  • Preparation of the nanofiber nonwoven fabric and the functional material of the PVA system is a fully hydrolyzed polyvinyl alcohol (PVA) of 98-99% saponification or partly hydrolyzed (85-89%) saponification. ) PVA.
  • the polymer solution used for the nanofiber nonwoven fabric or the polymer solution which is the functional material may contain a crosslinking agent.
  • the nanofiber nonwoven fabric is electrospinning, melt spinning, electro-blowing, melt-blowing (composite spinning, split yarn), using the polymer solution, It may be produced by a spun-bonded, air laid, or wet laid method.
  • the nanofiber nonwoven fabric has a thickness of 10 to 100 ⁇ m, the nanofibers constituting the nanofiber nonwoven fabric may have a diameter of 100 to 3000nm.
  • voltage delay may be prevented by coating a functional material on a polymer nanofiber nonwoven fabric.
  • the coated functional material serves to control the tensile strength, pore size, porosity, air permeability, heat shrinkage, and nonwoven fabric thickness of the nonwoven fabric, and also increase ion ion conductivity of lithium ions in the conventional lithium secondary battery electrolyte.
  • the present invention examined the possibility of applying the PVA polymer having excellent heat resistance and chemical resistance to the nonwoven fabric manufacturing step and the functional material coating step for each saponification degree and degree of polymerization, respectively. It was confirmed that there is no problem as a secondary battery separator material even when applied to the manufacturing step or the coating step, respectively.
  • It can be used as a secondary battery separator material of water-soluble PVA having a polymerization degree of more than 1,000, and it is possible to manufacture a separator with excellent economical efficiency at low cost, and to provide eco-friendly secondary battery separator and manufacturing technology using water as a solvent in nonwoven fabric manufacturing or coating stage. This is possible.
  • the method may further include pressing the nanofiber nonwoven fabric to control physical properties of the nanofiber nonwoven fabric and pressing the nanofiber nonwoven fabric may be performed before, after, or before and after coating the functional material.
  • the nonwoven separator obtained by the combination of the coating and the pressing process has no voltage delay in the lithium secondary battery, compared to the untreated nonwoven separator, which greatly increases the stability and increases the thickness and pore size. It can reduce and increase the tensile strength, it can also be improved heat resistance and air permeability compared to the conventional polyolefin-based separator.
  • 3 and 4 are the results showing the results of measuring the thickness and tensile strength according to the coating amount of the functional material of the coated PVA nanofiber nonwoven fabric and the pressed PVA nanofiber nonwoven fabric after coating, respectively.
  • 5 to 9 are graphs showing the results of coin cell evaluation of the PVA nanofiber nonwoven fabric prepared by electrospinning and the separator formed through the pressing step after coating using the same.
  • 10 to 12 are graphs showing the coin cell evaluation results of the pressed PVA nanofiber nonwoven fabric and the separator formed through the coating step using the same.
  • FIG. 13 is a graph showing LSV test results of a PVA nanofiber nonwoven fabric and a conventional PE separator according to an embodiment of the present invention.
  • FIG. 14 is a graph showing the experimental results of the voltage drop of a LiB cell to which a PVA nanofiber nonwoven fabric and a conventional PE separator according to an embodiment of the present invention after charging only.
  • FIG. 15 is a graph illustrating a change in anode and cathode potentials through a four-electrode experiment using a PVA nanofiber nonwoven fabric as a separator.
  • FIG. 16 is a graph showing a coin cell evaluation result when a conventional PE separator is padded on an anode and a PVA separator is applied.
  • FIG. 17 is a graph showing a coin cell evaluation result of PVA nanofiber separators pressed after coating PVA nanofibers formed by electrospinning with a mixture of PVDF and TPU.
  • FIGS. 18 and 19 are views showing the results of measuring the thickness and tensile strength of the membrane according to the coating amount of the composite nonwoven fabric membrane prepared by combining the nonwoven fabric, the coating step and the pressing step according to another embodiment of the present invention, respectively.
  • FIG. 20 is a view showing a coin cell evaluation result indicating a voltage delay phenomenon
  • FIG. 21 is a view showing a coin cell evaluation result indicating a state of normal charge and discharge characteristics
  • FIG. It is a figure which shows the coin cell evaluation result which shows.
  • the composite nonwoven fabric separator for a secondary battery according to an embodiment of the present invention may be used as a separator of a secondary battery such as a lithium secondary battery, and a method for manufacturing a composite nonwoven fabric separator for a secondary battery according to an embodiment of the present invention and a secondary manufactured therefrom A battery composite nonwoven separator will be described.
  • the method of manufacturing a composite nonwoven fabric separator for secondary batteries according to an embodiment of the present invention includes forming a nanofiber nonwoven fabric using a polymer solution in which a polymer is dissolved, and coating a functional material on the formed nanofiber nonwoven fabric. By coating the functional material, effects such as preventing a voltage delay of the separator can be obtained.
  • the method of manufacturing a composite nonwoven fabric separator for a secondary battery may further include pressing the nanofiber nonwoven fabric, and pressing the nanofiber nonwoven fabric may coat the above-mentioned functional material. It may be carried out after the step of carrying out or before the coating of the functional material. In addition, according to another embodiment of the present invention, pressing the nanofiber nonwoven fabric may be performed before and after coating the functional material, respectively. By pressing the nanofiber nonwoven fabric, it is possible to control the physical properties of the nanofiber nonwoven fabric so that the separator has desired characteristics.
  • the polymer used in the manufacture of the nanofiber nonwoven fabric is 1) cellulose derivative (for example, cellulose, cellulose acetate, etc.), chitin, chitosan, alginate, PVA (polyvinyl alcohol) having a degree of polymerization of 1,000 or less.
  • PSU poly sulfone
  • PEI Poly ether imide
  • 3) PVA polyimide
  • PVA poly (polyimide)
  • PVDF poly
  • PAN vinylidene fluoride
  • PAN poly acrylo nitrile
  • PEO poly ethylene oxide
  • PE polyethylene
  • PP poly propylene
  • PET polyethylene terephthalate
  • Mixture means a mixture of two or more polymers optionally selected from the listed polymers.
  • Nanofiber nonwoven fabric is formed using the polymer solution obtained by dissolving the above polymer.
  • the polymer solution used for the production of nanofibers may contain a crosslinking agent.
  • the crosslinking agent may be a generally known material.
  • the crosslinking agent of PVA is a peroxide-based, tetraethylolsosilicate and 3,3-diethoxypropyltriethoxysilane such as dibenzoyl peroxide.
  • Inorganic precursors such as silane coupling agent compounds, aldehydes such as glutaraldehyde, inorganic acids such as boric acid, polyacrylic acids, diisocyanates, diesides and their substituents, organic acids containing sulfone groups, or mixtures thereof Can be mentioned.
  • the crosslinking agent may be used for the purpose of minimizing the dissolution of nanofibers under the influence of moisture during long-term storage of the nanofibers or during post-treatment processes such as coating or pressing, in addition to the conventional crosslinking purpose.
  • Nanofiber nonwovens can be formed by electrospinning the polymer solution as described above, in addition to melt spinning, electro-blowing, melt-blowing (composite) Spun-bonded, spun-bonded, air laid, wet laid, or the like.
  • the nanofiber nonwoven fabric may have a thickness of 10 to 100 ⁇ m, the polymer nanofibers constituting the nanofiber nonwoven fabric may have a diameter of 100 to 3000nm.
  • the functional material coated on the nanofiber nonwoven fabric may be a polymer and may be a polymer or a blend thereof having heat resistance, stability to organic electrolytes, mechanical properties, high lithium ion conductivity, and the like, for example, the functional material may have a polymerization degree of more than 1,000.
  • Phosphorus PVA water soluble PEO (polyethylene oxide), PVDF (poly vinylidene fluoride), water soluble or water dispersible polyester-polyol (polyurethane, thermoplastic polyurethane), PAN (polyacrylonitrile), PMMA ( poly methyl methacrylate), and mixtures thereof.
  • the polymer solution used for the coating may include a crosslinking agent, and the functional material may be coated in excess of 20% of the coating amount.
  • the functional material may be coated on the nanofiber nonwoven fabric by spraying a functional material made of such a polymer solution on the nanofiber nonwoven fabric, or impregnating the nanofiber nonwoven fabric with the polymer solution.
  • the PVA system used for the production of nanofiber nonwoven fabrics and for the coating of functional materials is fully hydrolyzed polyvinyl alcohol (PVA) with a saponification degree of 98 to 99% or partially hydrolyzed with a degree of 85 to 89% saponification. hydrolyzed) PVA can be used regardless of the degree of saponification.
  • the secondary battery separator manufacturing method may include the step of pressing the nanofiber nonwoven fabric, it is possible to control the physical properties by pressing the nanofiber nonwoven fabric so that the separator can have the desired characteristics.
  • pressing of the nanofiber nonwoven fabric may be performed by pressing the polymer nanofiber nonwoven fabric or the polymer nanofiber nonwoven fabric coated with the functional material using a high pressure press equipment. At this time, pressing may be performed at a pressing pressure of 245 Kgf / cm (line pressure) or less and a pressing temperature of 70 ° C. or less.
  • the thickness and pore size can be reduced as compared with the polymer nanofiber nonwoven fabric before such treatment.
  • the tensile strength may be increased, and heat resistance and air permeability may be improved as compared with a conventional polyolefin-based separator.
  • a mixed solution obtained by adding a crosslinking agent was electrospun to prepare a nanofiber nonwoven fabric having a diameter of about 0.8 ⁇ m.
  • Figures 3 and 4 is a view showing the results of measuring the thickness and tensile strength, respectively, depending on the coating amount of the functional material of the prepared nanofiber nonwoven fabric. 3 and 4, as the coating amount was increased, the thickness and tensile strength were increased, and when the coated sample was pressed, the thickness was decreased and the tensile strength was increased as described above.
  • 5 to 9 are graphs showing the results of coin cell evaluation of the separator formed of the PVA nanofiber nonwoven fabric produced by electrospinning.
  • 5 is an evaluation result for the PVA nanofiber nonwoven fabric produced by electrospinning
  • Figure 6 is an evaluation result for the PVA nanofiber nonwoven fabric coated with PVDF
  • Figures 7 to 9 is a PVA nanofiber nonwoven fabric coated with PVDF The results of the evaluation of the nanofiber nonwoven fabric compressed through the pressing process at 94Kgf / cm, 195Kgf / cm, and 245Kgf / cm respectively.
  • Table 1 below shows the results of measuring physical properties of the samples of FIGS. 5, 6, 7, and 9.
  • PVA nanofiber nonwoven fabric produced by electrospinning increased the basis weight, tensile strength and heat resistance through coating.
  • the coating material is coated by penetrating from the surface to the back, a sample having a thickness of 30 ⁇ m, which is similar to the thickness of 29 ⁇ m before coating, was prepared even when a large amount of coating amount was coated.
  • the air permeability is 1.5 seconds and the existing PE separator is about 250 seconds.
  • 10 to 12 are graphs showing the results of coin cell evaluation of the separator formed of the pressed PVA nanofiber nonwoven fabric.
  • 10 is an evaluation result of the PVA nanofiber nonwoven fabric pressed at 245Kgf / cm using the PVA nanofiber nonwoven fabric produced by electrospinning
  • Figures 11 and 12 are 20% coating amount of the nonwoven fabric of FIG. And 50% coated PVA nanofiber nonwoven fabrics.
  • Table 2 below shows the results of measuring physical properties of the samples of FIGS. 10 to 12.
  • the PVA nanofibers produced by electrospinning decreased the thickness, increased tensile strength and air permeability through the pressing process, and the thermal shrinkage was the same.
  • the heat shrinkage was decreased and the air permeability was increased while maintaining the similar level of thickness and tensile strength.
  • the thickness increased slightly from 23 ⁇ m to 25 ⁇ m, but the thickness decreased and tensile strength and thermal shrinkage improved significantly compared to PVA nanofiber without coating and pressing process.
  • 10 to 12 show normal charge and discharge characteristics as a separator in a lithium secondary battery.
  • the PVA nanofibers prevent direct contact with the active material or electrolyte of the positive electrode (or negative electrode) and the voltage delay shape disappears. 6, 12) was confirmed.
  • the PVA nanofibers may be the positive electrode ( Or a negative electrode), which prevents direct contact with the active material or the electrolyte, resulting in a voltage delay during charging.
  • the cell was first charged to 4.2V and then the voltage change was observed for 100 hours. If an internal short circuit occurs, the voltage must continue to decrease over time. However, as can be seen from the results, it was confirmed that the actual voltage drop phenomenon was not observed even after 100 hours in the lithium secondary battery cell to which the PVA separator was applied similarly to the PE separator. This result is direct evidence that the voltage delay is not affected by internal short circuits.
  • PVDF and TPU thermoplastic polyurethane
  • the mixing ratio of PVDF and TPU is 4: 1 weight ratio
  • the coating amount is 50%
  • the thickness is reduced by 40% from 36 ⁇ m to 22 ⁇ m through the pressing process after coating
  • the tensile strength increases and the air permeability increases from 1.5 seconds to 8 seconds. It was.
  • the coin cell evaluation resulted in the disappearance of the voltage delay phenomenon during charging and normal charging and discharging characteristics. This is because the coating layer is not destroyed even when the elastic TPU is mixed with PVDF and pressed at a strong line pressure, thereby preventing direct contact between the PVA nanofibers and the cathode active material.
  • lithium secondary battery electrolytes carbonate-based organic solvents such as ethylene carbonate and propylene carbonate containing lithium salts
  • the resulting polymers include those containing OH groups in the molecular structure, such as cellulose, cellulose acetate, chitin, chitosan, alginate. These polymers have a good heat resistance at a melting temperature of 200 ° C. or higher, and are inexpensive, and thus can be used as a material for overcoming the shortcomings of conventional polyolefin-based separators or due to voltage delay.
  • Non-woven fabrics made of PI poly imide
  • PVDF poly imide
  • PAN poly acrylonitrile
  • PEO poly ethylene
  • PE poly ethylene
  • PP poly propylene
  • PET poly ethylene terephthalate
  • the thickness becomes thicker to 25 ⁇ m or more, which increases the ion conductivity of lithium ions in the lithium secondary battery. Combining the appropriate level of coating and pressing process obtained through the above results, it is possible to manufacture a separator having a thickness of 25 ⁇ m or less and improved tensile strength and thermal shrinkage.
  • a nonwoven fabric separator was prepared by combining a coating step using a PVDF or PVA-based coating solution with a cellulose nonwoven fabric and a pressing step, and applying this as a separator to evaluate a lithium secondary battery cell.
  • the cellulose nonwoven fabric was manufactured and provided in a wet-laid manner from a paper maker.
  • the first cellulose nonwoven fabric showed a voltage delay when evaluating the lithium secondary battery cell, but when pressed at a pressure of 94 Kgf / cm or less after coating with PVDF coated samples The voltage delay disappeared and normal charging and discharging characteristics were shown.
  • the values of thickness, tensile strength, and air permeability except heat shrinkage were controlled by the coating step and the pressing step. After the coating step, the basis weight increased, but the thickness decreased to 24 ⁇ m or less, compared with the original cellulose nonwoven fabric, and the tensile strength and air permeability increased. When coated with the same coating amount and pressed at the highest linear pressure of 245 Kgf / cm used in this study, the minimum thickness and the maximum tensile strength were obtained, but there was a problem when used as a separator due to voltage delay.
  • 18 and 19 are views showing the results of measuring the thickness and tensile strength of the separator according to the coating amount of the composite nonwoven fabric membrane prepared by combining the nonwoven fabric, the coating step and the pressing step. 18 and 19, as the coating amount increases, the thickness and tensile strength increase, and when the same coating amount is applied, the pressed sample after coating is the thinnest and thinner than the coated sample after pressing. It has a high tensile strength.
  • the coating step was possible to manufacture.
  • the appropriate coating amount and pressing pressure depends on the coating amount, the type of coating liquid and the material, thickness, and air permeability (or pore size) of the nonwoven fabric.
  • Table 6 and Table 7 show the results of the cellulose nonwoven membrane obtained by combining the coating step and the pressing step using PVA having a different degree of saponification and polymerization degree as the coating solution.
  • PVA was purchased from Aldrich and Guraray, and PVA with polymerization degree between 1,000 and 1,700 could not be obtained.
  • the cellulose nonwoven membrane coated with PVA with a degree of polymerization of 500 and 1,000 was still observed, and the voltage delay disappeared when coated with PVA with a degree of polymerization of 1,700.
  • the cellulose nonwoven fabric coated with PVA having a polymerization degree of 1,700 having the normal charge / discharge characteristic curve was subsequently subjected to a pressing step, voltage delay was observed in the sample pressed at a linear pressure of 245 Kgf / cm.
  • the thickness, tensile strength, and air permeability of the cellulose nonwoven fabric can be controlled by the combination of the PVA coating step and the pressing step, as in the results of FIGS. 18 and 19, and there is no voltage delay phenomenon.
  • Composite nonwoven membranes with maximum tensile strength and no heat shrinkage at 150 ° C while maintaining or reducing the thickness of the nonwoven fabric are coated with an appropriate coating amount using PVA with a degree of polymerization of more than 1,000 regardless of the degree of gumification, followed by pressing or pressing. Production was possible when the coating step.
  • the appropriate coating amount and pressing pressure depends on the coating amount, the type of coating liquid used, the material, thickness, air permeability (or pore size) of the nonwoven fabric, and the like.
  • FIG. 20 is a view showing a coin cell evaluation result indicating a voltage delay phenomenon
  • FIG. 21 is a view showing a coin cell evaluation result indicating a state of normal charge and discharge characteristics
  • the pressing step is performed under high linear pressure conditions.
  • the coating material, coating amount, The appropriate pressing pressure may be determined according to the material, thickness, and air permeability (or pore size) of the nonwoven fabric.
  • Experimental Example 6 is to overcome the limitations of the coating amount and pressing pressure mentioned above, if the original non-woven fabric is made of an electrochemically stable material in the secondary battery cell, the risk of voltage delay disappears,
  • the pressing pressure can be fixed to the maximum, so that the coating conditions (such as the amount of coating) can be easily determined to minimize the sheet thickness and to increase the tensile strength to the maximum.
  • a composite nonwoven separator was prepared by combining a PVDF nonwoven fabric with a coating step and a pressing step using a PVA coating solution having a polymerization degree of 1,700 mentioned in Experimental Example 5, and evaluated the lithium secondary battery cell by applying it as a separator.
  • Table 8 shows the PVDF composite nonwoven membrane manufactured by coating and pressing (linear pressure 245 Kgf / cm condition) using a coating solution obtained by dissolving PVA having a degree of polymerization of 1,700 in distilled water regardless of the degree of saponification on the nonwoven fabric obtained by electrospinning PVDF.
  • the physical properties and evaluation results of lithium secondary battery cells are shown.
  • PVDF composite non-woven membranes were coated and pressed under water-free conditions using chemical solvents using excellent PVA, which is excellent in heat resistance, chemical resistance and mechanical strength. While improving the tensile strength, it was possible to manufacture an optimal lithium secondary battery separator without a voltage delay phenomenon. In addition, no voltage delay was observed regardless of the amount of PVA coating, and no voltage delay was observed in the samples pressed at the highest linear pressure (245 Kgf / cm) used in this study.
  • the PVA nonwoven fabric used for the first time had no voltage delay as in the case of the PVDF nonwoven fabric, and thus there was no constraint on the coating amount and the pressing pressure.
  • the pressure was 245 Kgf / cm after the coating step. It was possible to manufacture a composite nonwoven fabric membrane for secondary batteries with reduced thermal shrinkage and minimum voltage and maximum tensile strength without voltage delay.
  • lithium secondary battery electrolytes carbonate-based organic solvents such as ethylene carbonate and propylene carbonate containing lithium salts
  • cellulose used in this experiment and polyvinyl alcohol with a polymerization degree of 1,000 or less
  • a polymer in which a voltage delay occurs may include a cellulose derivative such as cellulose acetate, a hydroxyl group ( ⁇ OH group) in a molecular structure such as chitin, chitosan, and alginate. These polymers have a good heat resistance at a melting temperature of 200 ° C.
  • the coating amount and pressing pressure are limited, so the appropriate coating amount and pressing pressure should be determined according to the properties of the nonwoven fabric such as the coating material used, the material and thickness of the nonwoven fabric, and the air permeability (or pore size). There is a hassle to manufacture.
  • the coating material, thickness, and permeability of the coating material, nonwoven fabric, and the like which are used in the same manner as those of polymers containing hydroxyl groups in the molecular structure, such as PVA nonwoven fabric and cellulose nonwoven fabric having a polymerization degree of 1,000 or less
  • the properties of the nonwoven fabric such as the pore size (or pore size)
  • the appropriate coating amount and the pressing pressure must be determined to prepare a membrane without a voltage delay phenomenon.
  • the heat shrinkage is 0% at 150 ° C and the thickness is maintained at the level of 20 to 25 ⁇ m, the tensile strength is improved, and the best secondary battery separator can be manufactured without the voltage delay phenomenon. .
  • the present invention relates to a method for manufacturing a separator for a secondary battery, which can be applied to a secondary battery and thus has industrial applicability.

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Wood Science & Technology (AREA)
  • Cell Separators (AREA)

Abstract

L'invention concerne un procédé de fabrication d'un séparateur en tissu non-tissé pour une batterie secondaire qui comprend les étapes suivantes : formation d'un tissu non-tissé en nanofibre par utilisation d'une solution de polymère dans laquelle un polymère est dissous ; et revêtement d'un matériau fonctionnel sur le tissu non-tissé en nanofibre. Le polymère utilisé dans la fabrication du tissu non-tissé en nanofibre peut être choisi parmi le groupe comprenant : 1) un polymère contenant un groupement hydroxyle (un groupement -OH) dans une structure moléculaire telle qu'un dérivé de cellulose, de chitine, de chitosane, d'alginate et d'alcool polyvinylique (PVA) ayant moins de 1000 en tant que degré de polymérisation ; 2) un polysulfone (PSU), un polyétherimide (PEI) ; 3) un PVA dépassant 1000 en degré de polymérisation, un polyimide (PI), un polyfluorure de vinylidène (PVDF), un polyacrylonitrile (PAN), un polyéthylène oxyde (PEO), un polyéthylène (PE), un polypropylène (PP), un polyéthylène téréphtalate (PET) ; et un mélange de ceux-ci. Le matériau fonctionnel peut être choisi parmi le groupe comprenant une base de PVA dépassant 1000 en degré de polymérisation, une base de PEO soluble dans l'eau, une base de PVDF, une base de polyol-polyester soluble dans l'eau ou dispersible dans l'eau, une base de PAN, une base de polyméthacrylate de méthyle (PMMA), et un mélange de ceux-ci.
PCT/KR2013/001965 2012-11-09 2013-03-12 Séparateur en tissu non-tissé complexe pour batterie secondaire et procédé de fabrication de celui-ci Ceased WO2014073750A1 (fr)

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KR10-2012-0126656 2012-11-09
KR20120126656A KR101490890B1 (ko) 2012-11-09 2012-11-09 이차전지용 분리막 및 그 제조 방법
KR20120148343A KR101490883B1 (ko) 2012-12-18 2012-12-18 이차전지용 복합부직포 분리막 및 제조방법
KR10-2012-0148343 2012-12-18

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Cited By (4)

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CN104610567A (zh) * 2015-01-26 2015-05-13 北京工业大学 一种基于无纺布支撑的pvdf/pan聚合物电解质膜的制备方法
CN112626713A (zh) * 2020-11-16 2021-04-09 广西中科鼎新产业技术研究院有限公司 一种纳米纤维膜及混合聚合物制备纳米纤维膜的方法
CN112915804A (zh) * 2021-01-12 2021-06-08 宁波方太厨具有限公司 一种一步法获得中空纤维纳滤膜的制备方法
WO2024090790A1 (fr) * 2022-10-24 2024-05-02 주식회사 엘지에너지솔루션 Procédé de préparation de séparateur pour batterie secondaire au lithium, séparateur pour batterie secondaire au lithium préparé à partir de celui-ci, et batterie secondaire au lithium le comprenant

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US6447958B1 (en) * 1998-04-27 2002-09-10 Sumitomo Chemical Co., Ltd. Non-aqueous electrolyte battery separator
EP1826842A1 (fr) * 2004-12-08 2007-08-29 Hitachi Maxell, Ltd. Separateur pour dispositif electrochimique et dispositif electrochimique
US7691528B2 (en) * 2002-08-24 2010-04-06 Degussa Ag Lithium battery separator having a shutdown function
KR20100113030A (ko) * 2009-04-10 2010-10-20 주식회사 엘지화학 다공성 코팅층을 포함하는 세퍼레이터, 그 제조방법 및 이를 구비한 전기화학소자
WO2012100049A1 (fr) * 2011-01-19 2012-07-26 E. I. Du Pont De Nemours And Company Séparateur pour pile au lithium présentant une fonction d'arrêt

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6447958B1 (en) * 1998-04-27 2002-09-10 Sumitomo Chemical Co., Ltd. Non-aqueous electrolyte battery separator
US7691528B2 (en) * 2002-08-24 2010-04-06 Degussa Ag Lithium battery separator having a shutdown function
EP1826842A1 (fr) * 2004-12-08 2007-08-29 Hitachi Maxell, Ltd. Separateur pour dispositif electrochimique et dispositif electrochimique
KR20100113030A (ko) * 2009-04-10 2010-10-20 주식회사 엘지화학 다공성 코팅층을 포함하는 세퍼레이터, 그 제조방법 및 이를 구비한 전기화학소자
WO2012100049A1 (fr) * 2011-01-19 2012-07-26 E. I. Du Pont De Nemours And Company Séparateur pour pile au lithium présentant une fonction d'arrêt

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104610567A (zh) * 2015-01-26 2015-05-13 北京工业大学 一种基于无纺布支撑的pvdf/pan聚合物电解质膜的制备方法
CN112626713A (zh) * 2020-11-16 2021-04-09 广西中科鼎新产业技术研究院有限公司 一种纳米纤维膜及混合聚合物制备纳米纤维膜的方法
CN112915804A (zh) * 2021-01-12 2021-06-08 宁波方太厨具有限公司 一种一步法获得中空纤维纳滤膜的制备方法
WO2024090790A1 (fr) * 2022-10-24 2024-05-02 주식회사 엘지에너지솔루션 Procédé de préparation de séparateur pour batterie secondaire au lithium, séparateur pour batterie secondaire au lithium préparé à partir de celui-ci, et batterie secondaire au lithium le comprenant

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