WO2014098519A1 - Porous separation membrane, secondary battery using same, and method for manufacturing said secondary battery - Google Patents

Porous separation membrane, secondary battery using same, and method for manufacturing said secondary battery Download PDF

Info

Publication number
WO2014098519A1
WO2014098519A1 PCT/KR2013/011952 KR2013011952W WO2014098519A1 WO 2014098519 A1 WO2014098519 A1 WO 2014098519A1 KR 2013011952 W KR2013011952 W KR 2013011952W WO 2014098519 A1 WO2014098519 A1 WO 2014098519A1
Authority
WO
WIPO (PCT)
Prior art keywords
porous
polymer
swellable polymer
electrolyte
nanofiber web
Prior art date
Application number
PCT/KR2013/011952
Other languages
French (fr)
Korean (ko)
Inventor
최원길
장주희
손용우
노승윤
서인용
Original Assignee
주식회사 아모그린텍
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
Priority claimed from KR1020120151137A external-priority patent/KR101576144B1/en
Priority claimed from KR1020130131035A external-priority patent/KR101576151B1/en
Application filed by 주식회사 아모그린텍 filed Critical 주식회사 아모그린텍
Publication of WO2014098519A1 publication Critical patent/WO2014098519A1/en
Priority to US14/743,043 priority Critical patent/US9647255B2/en

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
    • 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
    • H01M50/409—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
    • H01M50/417—Polyolefins
    • 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
    • H01M50/42—Acrylic 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
    • H01M50/449—Separators, membranes or diaphragms characterised by the material having a layered structure
    • H01M50/451—Separators, membranes or diaphragms characterised by the material having a layered structure comprising layers of only organic material and layers containing inorganic material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/489—Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
    • H01M50/491—Porosity
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • 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 porous separator, a secondary battery using the same, and a method for manufacturing the same.
  • a short circuit between two electrodes using a porous nanofiber web having a shell-core structure by mixing and spinning a nanofiber with a swellable polymer and a non-swellable polymer The present invention relates to a porous separator, a secondary battery using the same, and a method of manufacturing the same, which can simultaneously achieve safety and thinning.
  • Such a polymer battery uses a gel electrolyte in which a liquid electrolyte is impregnated in a polymer. Since the electrolyte is retained in the polymer, the liquid is less likely to leak, and therefore, there is an advantage in that the safety of the battery is improved and the shape of the battery can be freed.
  • the polymer electrolyte Since the polymer electrolyte has a lower conductivity of lithium ions than an electrolyte composed only of an electrolyte solution, a method of thinning the thickness of the polymer electrolyte is performed. However, when the polymer electrolyte is thinned in this manner, its mechanical strength is reduced, and the positive electrode and the negative electrode are short-circuited at the time of battery manufacturing, and thus the polymer electrolyte is easily destroyed.
  • Korean Patent No. 10-0637481 includes an anode, a polymer electrolyte, and a cathode, wherein the polymer electrolyte is a non-woven fabric having at least a gelling fiber and a non-gelling fiber which are easily gelled by an organic electrolyte solution.
  • the gelled fibers are impregnated with the organic electrolyte solution, the blending ratio of the gelled fibers and the non-gelled fibers is from 3:97 to 75:25 by weight, and the vinyl acetate content is 5
  • Lithium secondary batteries have been proposed which are polyacrylonitrile-vinyl acetate copolymers that are at least 20% by weight.
  • the polymer electrolyte proposed in Korean Patent No. 10-0637481 is impregnated with an organic electrolyte solution in a nonwoven fabric having at least gelled fibers and non-gelled fibers, the uniformity of the gelled fiber portion where gelation is performed by the impregnated organic electrolyte solution is ensured. Since it is impossible to guarantee uniform ion conductivity, there is a possibility of internal short, and since it has a nonwoven form, even thinning becomes difficult even if gelation is performed.
  • Korean Patent No. 10-1208698 discloses two different electrodes; Between the two electrodes, the mixture solution of 50 ⁇ 70% by weight heat-resistant polymer material having a melting point of 180 °C or more and swelling in the electrolyte solution 30 ⁇ 50% by weight swellable polymer material by air electrospinning (AES: Air-electrospinning) A heat resistant ultrafine fibrous porous membrane comprising the obtained ultrafine fibrous phase; And a secondary battery including an electrolyte solution or an electrolyte has been proposed.
  • AES Air-electrospinning
  • Korean Patent No. 10-1208698 uses a porous separator made of ultra-fine fibers obtained by spinning a mixed solution of a heat resistant polymer material and a swellable polymer material, and shows the advantages and advantages of the core-shell structure when the fiber has a core-shell structure. The conditions to form were not recognized.
  • Korean Patent Laid-Open No. 10-2012-46092 discloses an ultra-fine of a mixture of a heat-resistant polymer or a heat-resistant polymer, a swellable polymer, and an inorganic particle formed on a first non-porous polymer film layer and the first non-porous polymer film layer.
  • a heat resistant separator including a porous polymer web layer made of nanofibers has been proposed.
  • the heat resistant separator is a thin film having a 2-layer structure having a thickness of 10 to 60 um, the tensile strength is low, so handling is poor at the time of production, and there is a problem in that it is not competitive due to high manufacturing cost.
  • nanofibers may have better relative strength than other fibers, but their absolute strength is weak.
  • nanofibers have a large amount of static electricity in the manufacturing process, there is a problem that handling is very difficult by itself. Although it is impossible to remove static electricity through the compounding of paper and the like, the handleability can be improved.
  • the polymer web separator has a porosity of about 80%, micro-short occurs because the ions move too well, resulting in a decrease in open circuit voltage (OCV).
  • Nonwoven fabrics made of PP / PE or PET fibers have too high porosity and cannot be used as separators by themselves.
  • the nonwoven fabric has a porosity of 70 to 80%, there is a problem in that pores exist that have poor OCV characteristics due to self discharge, and large pore deviations.
  • a separator having low porosity and enhanced heat resistance by adding a ceramic layer by mixing inorganic particles with a binder to a nonwoven fabric has a complicated manufacturing process and has a problem in that inorganic particles are detached.
  • the present inventors have found that the nanofibers spun by mixing a swellable polymer and a non-swellable polymer that are swollen and electrolytically in an electrolyte solution have a core-shell structure when the molecular weight difference between the two polymers to be mixed is more than a set value.
  • the non-swellable polymer having a large molecular weight is located in the core portion of the nanofiber, and the swellable polymer having a small molecular weight is located in the v portion.
  • the non-swellable polymer was found to have a relatively high melting point because of its high molecular weight compared to the swellable polymer.
  • the gelation proceeds at a temperature higher than the melting point of the swellable polymer and lower than the melting point of the non-swellable polymer in the heat treatment process for gelation, even though the swellable polymer shell placed outside the nanofibers is gelated.
  • Non-swellable polymer cores disposed inside have been shown to maintain the matrix shape as only slight swelling occurs and the chain remains unbroken. The present invention has been made based on this finding.
  • the present invention has been proposed to solve the above problems of the prior art, the object of which is that the nanofibers constituting the porous nanofiber web forms a shell-core structure and the swellable polymer shell disposed outside is gelled. Since the non-swellable polymer core disposed inside maintains the web shape uniformly with respect to the entire polymer electrolyte membrane, there is provided a secondary battery using a polymer electrolyte capable of improving safety by preventing a short circuit between the positive electrode and the negative electrode and a manufacturing method thereof. There is.
  • Another object of the present invention is to use a porous nanofiber web made of nanofibers having a core-shell structure as an electrolyte matrix, and a secondary battery using a polymer electrolyte capable of ensuring fast and uniform electrolyte impregnation of an organic electrolyte, and a method of manufacturing the same.
  • the present invention provides a secondary battery using a polymer electrolyte capable of increasing ionic conductivity with a thin film and a method of manufacturing the same.
  • Another object of the present invention is to wrap the outside of the electrode assembly with a non-swellable porous thin film sheet to prevent the separation between the electrolyte and the electrode by inhibiting the shape of the electrode assembly expansion and contraction during charging and discharging progress
  • the present invention provides a secondary battery capable of suppressing an increase in interfacial resistance and a method of manufacturing the same.
  • Another object of the present invention is to reduce the porosity (porosity) by adding a thin inorganic porous film or porous nanofiber web to one side of the porous non-woven fabric used as a support can suppress the OCV (open circuit voltage) lowering phenomenon It is to provide a porous separator and a secondary battery using the same.
  • Another object of the present invention is to use a porous non-woven fabric which can be used as a strength support and can be obtained at low cost to increase the tensile strength and to improve handling in production, and to apply a thin inorganic porous film or a porous nanofiber web. Accordingly, the present invention provides a porous separator and a secondary battery using the same, which can significantly lower the manufacturing price.
  • the present invention provides a porous nonwoven fabric having a micropore as a supporter; And a porous nanofiber web stacked on one side of the porous nonwoven fabric and serving as an adhesive layer and an ion-moisture layer when in close contact with an opposite electrode, and part of the porous nanofiber web partially blocks pores of the porous nonwoven fabric. It is incorporated into the surface layer of the porous nonwoven fabric to provide a porous separator, characterized in that to lower the porosity of the porous nonwoven fabric.
  • the present invention provides a porous nonwoven fabric having a micropore as a supporter; And a non-porous film laminated on one side of the porous nonwoven fabric and serving as an adhesive layer and an ion moisturizing layer when in close contact with an opposite electrode, and a portion of the non-porous film may be formed of the porous nonwoven fabric to block pores of the porous nonwoven fabric. It provides a porous separator characterized in that it is embedded in the surface layer.
  • the porous nanofiber web is preferably made of a polymer that swells in the electrolyte and is capable of conducting electrolyte ions.
  • the polymer may be any one of PVDF, PEO, PMMA, and TPU.
  • the polymer is preferably a CTFE (Chlorotrifluoroethylene) PVDF copolymer or HFP (hexafluoropropylene) PVDF copolymer.
  • CTFE-based PVDF copolymer may contain 15 to 20 wt% of CTFE in VF (vinylidene fluoride), and the HFP-based PVDF copolymer may contain 4 to 12 wt% of HFP in VF.
  • the thickness of the porous nanofiber web is set to a range of 1 to 10um, the thickness of the porous nonwoven fabric is preferably set to a range of 10 to 40um.
  • the porous nonwoven fabric may be any one of a nonwoven fabric made of a double structure PP / PE fiber coated with PE on the outer circumference of the PP fiber as a core, a PET nonwoven fabric made of polyethylene terephthalate (PET) fiber, and a nonwoven fabric made of cellulose fiber. have.
  • the porous nanofiber web includes a plurality of nanofibers each having a shell-core structure along a longitudinal direction, each of the plurality of nanofibers is disposed on the outside and swellable polymer shell made of a swellable polymer swelling in the organic electrolyte; It is preferred to include a non-swellable polymer core made of a non-swellable polymer.
  • the molecular weight difference between the swellable polymer and the non-swellable polymer is 20 times or more.
  • the porous nanofiber web preferably comprises 40 to 90% by weight non-swellable polymer and 10 to 60% by weight of swellable polymer.
  • the present invention includes a positive electrode, a negative electrode, a separator for separating the positive electrode and the negative electrode and the electrolyte, the separator is a porous non-woven fabric that serves as a support and has micropores; And a porous nanofiber web stacked on one side of the porous nonwoven fabric and serving as an adhesive layer and an ion-moisture layer when in close contact with an opposite electrode, and part of the porous nanofiber web partially blocks pores of the porous nonwoven fabric. It is embedded in the surface layer of the porous nonwoven fabric to provide a secondary battery characterized in that to lower the porosity of the porous nonwoven fabric.
  • the porous nanofiber web is made of a polymer that swells in the electrolyte and is capable of conducting electrolyte ions, and the polymer is preferably a CTFE PVDF copolymer or an HFP PVDF copolymer.
  • the porous nanofiber web includes a plurality of nanofibers each forming a shell-core structure along the longitudinal direction, each of the plurality of nanofibers are disposed on the outside and swellable polymer shell made of a swellable polymer swelling in the electrolyte solution And a non-swellable polymer core made of a non-swellable polymer.
  • the porous nanofiber web is impregnated with an electrolyte solution in which a lithium salt is dissolved in a non-aqueous organic solvent, and as a gelation process is performed, the swellable polymer shell disposed outside the nanofiber is gelled by an electrolyte solution.
  • the non-swellable polymer core disposed inside maintains the web shape.
  • the porous nanofiber web forms a polymer electrolyte as the gelation process is performed.
  • the positive electrode and the negative electrode each include a plurality of unit electrode cells stacked alternately, separated into the polymer electrolyte, and the plurality of positive and negative electrode unit cells separated and stacked by the polymer electrolyte are expanded in the stacking direction. It is preferable to further include a compression band for blocking the thing.
  • the present invention separates a plurality of unit cathode cells and a plurality of unit cathode cells using a pair of porous nanofiber webs each including a plurality of nanofibers each composed of a non-swellable polymer and a swellable polymer.
  • a pair of porous nanofiber webs each including a plurality of nanofibers each composed of a non-swellable polymer and a swellable polymer.
  • a compression band taping the outer circumference of the electrode assembly
  • an electrode assembly taped by the compression band, and including a case in which an electrolyte is injected, and a swellable polymer shell disposed outside of the nanofibers is gelled by an electrolyte as the gelation process is performed.
  • the non-swellable polymer core that is disposed provides a secondary battery characterized by maintaining a web shape.
  • the present invention comprises the steps of dissolving the swellable polymer and the non-swellable polymer in a solvent to form a mixed polymer spinning solution; Spinning the mixed polymer spinning solution to form a porous nanofiber web composed of a plurality of nanofibers in which the swellable polymer and the non-swellable polymer form a shell-core structure; Forming an electrode assembly by inserting the porous nanofiber web between an anode and a cathode each consisting of a plurality of unit electrode cells; Embedding the electrode assembly in a case and injecting an electrolyte solution; And performing a gelling heat treatment to swell the swellable polymer shell disposed on the outside of the nanofibers with an electrolyte solution, wherein the non-swellable polymer core disposed on the inside of the nanofibers maintains a web shape. It provides a secondary battery manufacturing method.
  • the porous nanofiber web is formed by spinning the mixed polymer spinning solution on a strip-shaped transfer sheet, the forming of the electrode assembly is a pair of porous nano on both sides while continuously transporting the plurality of unit electrode cells Encapsulating with a fibrous web; And separating the transfer sheets from the pair of porous nanofiber webs after the encapsulation step, respectively.
  • the nanofiber web formed by the nanofibers swelled and mixed with the non-swellable polymer, which swells in the electrolyte and gels, it is impregnated with a uniform electrolyte solution as the organic electrolyte is impregnated. Can be guaranteed.
  • the nanofibers constituting the porous nanofiber web form a shell-core structure
  • the non-swellable polymer core disposed on the inside of the swellable polymer shell disposed on the outside with respect to the entire polymer electrolyte membrane even if gelation occurs.
  • the non-swellable polymer core that maintains the web shape in the porous separator remains between the positive electrode and the negative electrode, the polymer electrolyte itself can be made as thin as the swellable polymer shell filled in the positive and negative electrodes, and the positive electrode is uniformly impregnated. It is possible to increase the ionic conductivity between the cathode and the cathode.
  • the adhesive layer of the thin film on the outer side of the polymer electrolyte by providing the adhesive layer of the thin film on the outer side of the polymer electrolyte, it is possible to improve the adhesion with the positive electrode or the negative electrode and to prevent the short circuit due to the growth of lithium dendrites.
  • the expansion and contraction of the electrode assembly is induced in the lateral direction instead of the vertical direction of the electrode assembly during charging and discharging to separate the electrolyte and the electrode.
  • OCV open circuit voltage
  • part of the swellable polymer is adhered to the positive electrode and the negative electrode and the polymer electrolyte by being charged to the positive electrode and the negative electrode in a continuous state with the polymer electrolyte, thereby reducing the OCV (open circuit voltage). It can be minimized.
  • micro shorts are not generated by reducing the porosity (porosity), and the OCV degradation phenomenon can be suppressed.
  • the tensile strength can be increased to improve handling in production, and by applying an ultra-thin inorganic porous film or a porous nanofiber web, The manufacturing price can be significantly lowered.
  • the electrolytic solution is formed by swelling the electrolyte and electrospinning a polymer capable of conducting electrolyte ions directly onto the porous nonwoven fabric so that a part of the ultra-thin inorganic porous film or the porous nanofiber web is formed on one surface of the nonwoven fabric.
  • Excellent impregnation ability and adhesiveness can provide a composite porous membrane in the form of a thin film.
  • porous separator of the present invention by strengthening the adhesion to the electrode by forming an ultra-thin inorganic porous film or porous nanofiber web on one side of the porous non-woven fabric used as a support to remove or peel off the separation membrane generated during the assembly process Etc., it is possible to improve the safety of the secondary battery and to prevent degradation of performance.
  • the porous separator of the present invention when laminating an ultra-thin inorganic porous film or porous nanofiber web with a nonwoven fabric and the like, improves the strength of the nanofibers by making it possible to realize valuable products even with low-weight nanofibers through lamination. This can contribute to low costs.
  • FIG. 1 is a cross-sectional view showing a lithium secondary battery according to a first embodiment of the present invention
  • FIG. 2 is a cross-sectional view showing a rechargeable lithium battery according to a second embodiment of the present invention.
  • FIG. 3 is a cross-sectional view illustrating a process of manufacturing a porous separator used as a polymer electrolyte according to the present invention
  • FIG. 4 is a cross-sectional view illustrating a sealing process of a porous separator used as a positive electrode and a polymer electrolyte according to the present invention
  • FIG. 5 is a schematic cross-sectional view of an electrode assembly assembled according to the present invention.
  • FIG. 6 is a schematic plan view of an electrode assembly assembled according to the present invention.
  • FIG. 7 is a flowchart illustrating an assembly process of a lithium secondary battery according to the present invention.
  • FIG. 10 is a manufacturing process diagram for manufacturing a composite porous separator according to the present invention
  • FIG. 11 is a modified manufacturing process chart for manufacturing a composite porous separator according to the present invention.
  • the polymer electrolyte is obtained by assembling a porous separator or a porous nanofiber web together with a positive electrode and a negative electrode inside a case, and then injecting the organic electrolyte into the case and incorporating the organic electrolyte into the porous separator and then performing a gelation process. It refers to a gel polymer electrolyte of an inorganic pore type in which a liquid organic solvent does not substantially remain.
  • the porous separator used to form the polymer electrolyte is composed of a single layer of nanofiber web, the nanofiber web may be used to mean a porous separator.
  • FIG. 1 is a cross-sectional view illustrating a lithium secondary battery according to a first preferred embodiment of the present invention
  • FIG. 2 is a cross-sectional view illustrating a lithium secondary battery according to a second preferred embodiment of the present invention.
  • a lithium secondary battery according to a first preferred embodiment of the present invention that is, a lithium polymer battery, includes a cathode 1, an inorganic pore-type gel polymer electrolyte 5, and a full cell.
  • a cathode 3 is provided.
  • the positive electrode 1 has a positive electrode active material layer 11b on one surface of the positive electrode current collector 11a
  • the negative electrode 3 has a negative electrode active material layer 13b on one surface of the negative electrode current collector 13a.
  • the positive electrode 1 may be disposed to face the negative electrode 3 and include a pair of positive electrode active material layers on both sides of the positive electrode current collector 11a to form a bicell.
  • the cathode active material layer 11b includes a cathode active material capable of reversibly intercalating and deintercalating lithium ions.
  • Representative examples of the cathode active material include LiCoO 2 , LiNiO 2 , LiNiCoO 2 , and LiMn 2 O.
  • a substance capable of occluding and releasing lithium such as 4 , LiFeO 2 , V 2 O 5 , V 6 O 13 , TiS, MoS, or an organic disulfide compound or an organic polysulfide compound can be used.
  • the negative electrode active material layer 13b includes a negative electrode active material capable of intercalating and deintercalating lithium ions, and the negative electrode active material includes a carbon-based negative electrode active material of crystalline or amorphous carbon, carbon fiber, or carbon composite material. , Tin oxides, lithiated ones thereof, lithium, lithium alloys and mixtures thereof. However, the present invention is not limited to the type of the negative electrode active material.
  • the positive electrode 1 and the negative electrode 3 prepare a slurry by mixing an appropriate amount of an active material, a conductive agent, a binder, and an organic solvent, as in the method generally used in a conventional lithium ion battery, and then prepare a positive electrode and a negative electrode current collector ( 11a, 13a) can be obtained by casting, drying and rolling the prepared slurry on both sides of aluminum or copper foil or mesh.
  • the positive electrode is used by casting a slurry composed of LiCoO 2 , super-P carbon, PVdF as an active material, a conductive agent, a binder on an aluminum foil, and the negative electrode is MCMB (mesocarbon microbeads), super-P carbon, PVdF
  • MCMB mesocarbon microbeads
  • the constructed slurry can be cast and used on copper foil.
  • the polymer electrolyte 5 is a porous nanofiber web 15 made of nanofibers 150 having a core-shell structure, that is, spun with a swellable polymer and a non-swellable polymer that are swollen in an electrolyte and gelled, that is, porous It was obtained by incorporating an organic electrolyte solution into the separator and subjecting it to a gelation heat treatment step.
  • the porous nanofiber web 15 is formed by dissolving a mixture of a swellable polymer and a non-swellable polymer that swell in an organic electrolyte solution in a solvent to form a spinning solution, and then spinning a spinning solution to collect ultrafine nanofibers.
  • a porous nanofiber web is formed, and a porous separator is formed by calendering at a temperature below the melting point of the polymer.
  • the spinning solution may contain a predetermined amount of inorganic particles to enhance heat resistance.
  • the swellable polymers and non-swellable polymers may be present in a weight ratio ranging from 4: 6 to 1: 9, preferably in a weight ratio ranging from 5: 5 to 3: 7. It is preferable to mix.
  • the lithium ion conductivity is increased, but the swelling property of the swellable polymer becomes too large and serves as a separator that physically isolates the positive electrode 1 and the negative electrode 3.
  • the amount of non-swellable polymer is reduced, resulting in poor heat resistance and strength. That is, when the gelation process is impregnated after impregnating the organic electrolyte, the swellable polymer shell 150a disposed on the outside becomes swollen, and the non-swellable polymer core 150b disposed on the inside uniformly covers the entire web of the polymer electrolyte membrane. It is difficult to maintain the shape, and as a result, as the non-swellable polymer core 150b does not function as a separator, short circuit between the positive electrode and the negative electrode is prevented, thereby making it difficult to achieve safety.
  • the mixing ratio of the swellable polymer and the non-swellable polymer is greater than 1: 9 by weight ratio, even if the electrolyte is not impregnated well and the swellable polymer is swelled, the amount of the swollen polymer is small and the pores of the web cannot be blocked and the lithium ion conductivity At the same time decreases the radioactivity and radiation problems occur.
  • the spun nanofiber 150 has a core-shell structure when the molecular weight difference between the two polymers to be mixed is greater than or equal to a set value.
  • the spun nanofibers 150 are composed of a core-shell structured nanofiber 150 surrounded by the swellable polymer shell 150a on the outside of the non-swellable polymer core 150b.
  • the nanofiber 150 has a core-shell structure when the low temperature porous nanofiber web 15 is a hydrophobic material and exhibits hydrophobic properties by polyvinylidene fluoride (PVdF) disposed on the outside.
  • PVdF polyvinylidene fluoride
  • fusing point it can confirm from changing into hydrophilicity by polyacrylonitrile (PAN) which is a hydrophilic material.
  • the difference in molecular weight is preferably 20 times or more, and it is required to be a polymer that can be made of nanofibers by spinning after dissolving in a solvent. do.
  • the non-swellable polymer was found to have a relatively high melting point because of its high molecular weight compared to the swellable polymer.
  • the non-swellable polymer is preferably a resin having a melting point of 180 ° C. or higher, and the swellable polymer is preferably a resin having a melting point of 150 ° C. or lower, preferably in the range of 100 to 150 ° C.
  • non-swellable polymers are polymers which are relatively slow or do not swell with a solvent contained in the organic electrolyte due to the difference in molecular weight when compared with the swellable polymer.
  • the swellable polymer is required to be made of a polymer having excellent conductivity so as to serve as a path for transporting lithium ions that are oxidized or reduced at the cathode and the anode during charging and discharging of the battery.
  • the swellable polymers usable in the present invention are resins that swell in the electrolyte and can be formed into ultrafine fibers by electrospinning.
  • PVDF polyvinylidene fluoride
  • perfuluropolymer polyvinylchloride or polyvinylidene chloride and copolymers thereof and polyethylene glycol derivatives including polyethylene glycol dialkyl ether and polyethylene glycol dialkyl ester
  • poly (oxymethylene-oligo-oxy Ethylene) polyoxides including polyethylene oxide and polypropylene oxide
  • polyvinylacetate poly (vinylpyrrolidone-vinylacetate)
  • polystyrene and polystyrene acrylonitrile copolymers polyacrylonitrile methyl methacrylate copolymers
  • Polyacrylonitrile containing Copolymers polymethyl methacrylates, polymethyl me
  • non-swellable polymers usable in the present invention can be dissolved in an organic solvent for electrospinning, and swelling is slower than swelling polymers or swelling by an organic solvent included in the organic electrolyte, and the resin has a melting point of 180 ° C or higher.
  • polyacrylonitrile PAN
  • polyamide polyimide, polyamideimide, poly (meth-phenylene isophthalamide), polysulfone, polyetherketone, polyethylene terephthalate, polytrimethylene Aromatic polyesters such as telephthalate, polyethylene naphthalate and the like, polyphosphazenes such as polytetrafluoroethylene, polydiphenoxyphosphazene, poly ⁇ bis [2- (2-methoxyethoxy) phosphazene], poly Polyurethane copolymers including urethanes and polyetherurethanes, cellulose acetates, cellulose acetate butylenes Yite, cellulose acetate propionate, etc. can be used.
  • PAN polyacrylonitrile
  • polyamide polyimide
  • polyamideimide poly (meth-phenylene isophthalamide)
  • polysulfone polyetherketone
  • polyetherketone polyetherketone
  • polyethylene terephthalate polytrim
  • the porous nanofiber web 15 is formed of the core-shell structured nanofibers 150 surrounded by the swellable polymer shell 150a on the outside of the non-swellable polymer core 150b.
  • the spinning solution used in the preparation of the swellable polymer and the non-swellable polymer are mixed to form a mixed polymer, it is necessary to select the difference in molecular weight. Therefore, it is preferable to combine so that the difference in molecular weight between the swellable polymer and the non-swellable polymer is at least 20 times or more.
  • the porous nanofiber web 15 is obtained by spinning the spinning solution in which the swellable polymer and the non-swellable polymer are dissolved, it is preferable to spin using the air-electrospinning (AES) equipment shown in FIG. Do.
  • AES air-electrospinning
  • the spinning methods usable in the present invention include, in addition to air electrospinning (AES), electrospinning, electrospray, electroblown spinning, centrifugal electrospinning, and flash electrospinning (flash). electrospinning).
  • AES air electrospinning
  • electrospinning electrospinning
  • electrospray electrospray
  • electroblown spinning electroblown spinning
  • centrifugal electrospinning centrifugal electrospinning
  • flash flash electrospinning
  • the porous nanofiber web 15 produced by air electrospinning is preferably 10 to 25 mu m, more preferably 10 to 15 mu m.
  • AES air electrospinning
  • the thickness of the porous nanofiber web 15 is less than 10 ⁇ m, a short may occur because the thickness of the non-swellable polymer core 150b remaining after gelation of the swellable polymer shell 150a is made too thin.
  • the thickness exceeds 25 ⁇ m the thickness of the gelled swellable polymer shell 150a also increases, resulting in poor ionic conductivity.
  • the organic electrolyte embedded in the porous nanofiber web 15 of the polymer electrolyte 5 includes a non-aqueous organic solvent and a solute of lithium salt.
  • the organic solvent has excellent solubility in the swellable polymer, low solubility in the non-swellable polymer, and the nanofiber 150 has a core-shell structure, and the swellable polymer shell 150a is disposed outside the fiber. Therefore, the organic solvent of the organic electrolyte solution embedded in the porous nanofiber web 15 mainly gelates the swellable polymer and plasticizes it.
  • carbonate As the non-aqueous organic solvent, carbonate, ester, ether or ketone may be used.
  • the carbonate may be dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylpropyl carbonate (EPC), methylethyl carbonate (MEC), ethylene carbonate (EC) , Propylene carbonate (PC), butylene carbonate (BC) and the like
  • the ester is butyrolactone (BL), decanolide (decanolide), valerolactone (valerolactone), mevalonolactone (mevalonolactone ), Caprolactone (caprolactone), n-methyl acetate, n-ethyl acetate, n-propyl acetate and the like
  • the ether may be dibutyl ether and the like
  • the ketone is polymethyl vinyl ketone
  • the present invention
  • the lithium salt acts as a source of lithium ions in the battery to enable operation of the basic lithium battery, for example, LiPF 6 , LiBF 4 , LiSbF 6 , LiAsF 6 , LiClO 4 , LiCF 3 SO 3 , LiN (CF 3 SO 2 ) 2 , LiN (C 2 F 5 SO 2 ) 2 , LiAlO 4 , LiSbF 6 , LiCl, LiI, LiAlCl 4 , LiN (C x F 2x + 1 SO 2 ) (C y F 2x + 1 SO 2 ), wherein x and y are natural water and LiSO 3 CF 3 includes one or more or mixtures thereof.
  • the inorganic particles are Al 2 O 3 , TiO 2 , BaTiO 3 , Li 2 O, LiF, LiOH, Li 3 N, BaO, Na 2 O, Li 2 CO 3 , CaCO 3 , LiAlO 2 , SiO 2 , SiO, SnO , SnO 2 , PbO 2 , ZnO, P 2 O 5 , CuO, MoO, V 2 O 5 , B 2 O 3 , Si 3 N 4 , CeO 2 , Mn 3 O 4 , Sn 2 P 2 O 7 , Sn 2 B 2 O 5, Sn 2 BPO 6 and can be used at least one member selected from among those of the respective mixtures.
  • the content of the added inorganic particles is preferably contained in the range of 10 to 25% by weight based on the total mixture when the size of the inorganic particles is between 10 and 100 nm. Do. More preferably, the inorganic particles are contained in the range of 10 to 20% by weight, and the size is in the range of 15 to 25 nm.
  • the film does not maintain the film form, shrinkage occurs, the desired heat resistance characteristics are not obtained, and if it exceeds 25% by weight, the radiation troubles that contaminate the spinning nozzle tip Phenomenon occurs and the solvent volatilization is fast and the film strength decreases.
  • the size of the inorganic particles is less than 10nm, the volume is too large and difficult to handle, and when it exceeds 100nm, the phenomenon that the inorganic particles are agglomerated occurs a lot of exposed outside the fiber causes the strength of the fiber is lowered.
  • the present invention as shown in the second embodiment shown in Figure 2, the inorganic porous polymer film layer of the ultra-thin film laminated on one side or both sides of the gel polymer electrolyte of the inorganic type of the first embodiment (2) used as an adhesive layer ( 5a).
  • the polymer is first mixed by air electrospinning (AES) using, for example, a multi-hole spinning pack in which the spinning nozzles are spaced along the direction of the collector.
  • AES air electrospinning
  • the second nanofiber web of the thin film was first formed by using the second spinning solution in which a single polymer was dissolved. Stacked on top of 15 to form first and second porous nanofiber webs of two-layer structure.
  • the polymer used to prepare the second spinning solution is a polymer resin that swells in the electrolyte and is capable of conducting lithium ions and has excellent adhesion, and includes PVDF (polyvinylidene fluoride) and PEO (Poly-Ethylen Oxide)
  • PVDF polyvinylidene fluoride
  • PEO Poly-Ethylen Oxide
  • PMMA polymethyl methacrylate
  • TPU Thermoplastic Poly Urethane
  • a polymer having excellent swelling and excellent ion conductivity and adhesiveness, such as PVDF is preferable.
  • an infrared lamp heater is used as the second porous nanofiber web to set the first and second porous nanofiber webs having a two-layer structure at a temperature slightly lower than the melting point of the second porous nanofiber web.
  • the second porous nanofiber web is converted into the inorganic porous film 5a to obtain a laminated structure of the first porous nanofiber web 15 and the inorganic porous film 5a.
  • the inorganic porous film 5a is formed to have a thickness of 2 to 5 ⁇ m, and when the thickness is less than 2 ⁇ m, the function of the adhesive layer is weak. Will be lowered.
  • FIG. 3 is a cross-sectional view showing a manufacturing process of a porous separator used as a polymer electrolyte according to the present invention
  • FIG. 4 is a cross-sectional view showing a sealing process of a porous separator used as a positive electrode and a polymer electrolyte according to the present invention
  • FIG. 6 is a schematic plan view of an electrode assembly assembled in accordance with the present invention.
  • the porous nanofiber web 15 is manufactured by, for example, air electrospinning (AES).
  • AES air electrospinning
  • the collector 26 is applied by applying a high voltage electrostatic force of 90 to 120 Kv between the spinning nozzle 24 and the collector 26 to which the mixed spinning solution having a sufficient viscosity is radiated using the air spray electrospinning device shown in FIG.
  • the ultrafine nanofibers 150 are radiated to form a porous nanofiber web 15, in which case the radiated nanofibers 150 are sprayed by injecting air 24a at each spinning nozzle 24 to the collector 26. It can't be captured and catches flying.
  • the mixed spinning solution is prepared by adding 40-90 wt% non-swellable polymer material and 10-60 wt% of swellable polymer material to a two-component solvent or a one-component solvent.
  • the solvent used for the mixed spinning solution is preferably a two-component solvent in which a boiling point (BP) is mixed with a high boiling point.
  • the air spray electrospinning apparatus used in the present invention is a stirrer 22 using a mixing motor 22a using pneumatic pressure as a driving source to prevent phase separation until a non-swellable polymer material and a swellable polymer material are mixed with a solvent and spinning. It includes a mixing tank (Mixing Tank) 21, and a multi-hole nozzle pack (not shown) in which a plurality of spinning nozzles 24 to which a high voltage generator is connected are arranged in a matrix form.
  • the mixed spinning solution discharged from the mixing tank 21 to a plurality of spinning nozzles 24 connected through a metering pump and a transfer pipe 23, not shown, passes through the spinning nozzles 24 charged by the high voltage generator, and the nanofibers.
  • the nanofibers 150 are accumulated on a grounded collector 26 in the form of a conveyor which is discharged to 150 and moves at a constant speed to form a porous nanofiber web 15.
  • the transfer sheet 25a having a high tensile strength is transferred from the transfer roll 25 to the upper part of the collector 26 of the air spray electrospinning apparatus so as to improve the workability of the subsequent process and the positive electrode encapsulation process described later.
  • the continuous nano fiber web 15 is formed by laminating the upper portion of the transfer sheet 25a.
  • the transfer sheet 25a may be, for example, a polyolefin-based film such as nonwoven fabric, PE, PP, or the like, which is made of paper or a polymer material that is not dissolved by a solvent contained therein when spinning a mixed spinning solution. .
  • a polyolefin-based film such as nonwoven fabric, PE, PP, or the like, which is made of paper or a polymer material that is not dissolved by a solvent contained therein when spinning a mixed spinning solution.
  • the porous nanofiber web 15 itself, the tensile strength is low, so that the drying process, the calendering process, and the winding process are difficult to be carried out at a high feed rate.
  • the subsequent encapsulation process with the positive or negative electrode is difficult to be carried out continuously with a high feed rate, but when the transfer sheet 25a described above is used, sufficient tensile strength is provided.
  • the processing speed can be greatly increased.
  • the transfer sheet 25a is subjected to roll pressing with an electrode as shown in FIG. 4, and then peeled off and removed.
  • Nanofiber web 15 made of ultra-fine fibers is an ultra-thin film, ultra-light weight, has a high surface area to volume ratio and high porosity.
  • porous nanofiber web 15 obtained as described above is then passed through a pre-air dry zone by the preheater 28 and the solvent and water remaining on the surface of the porous nanofiber web 15. After going through the process of adjusting the amount of calendering process using a heat compression roller 29 is made.
  • Pre-Air Dry Zone by the preheater 28 is a solvent remaining on the surface of the porous nanofiber web 15 by applying air of 20 ⁇ 40 °C to the web using a fan (fan)
  • By controlling the amount of moisture and the porous nanofiber web 15 is to control the bulky (bulky) to increase the strength of the membrane and at the same time it is possible to control the porosity (Porosity).
  • the heat compression roller 29 is used, and in this case, if the calendering temperature is too low, the web is too large. If it is bulky and has no rigidity and is too high, the web melts and the pores are blocked. In addition, thermocompression should be performed at a temperature that can completely volatilize the solvent remaining on the web, and if the volatilization is performed too little, the web will melt.
  • the heat compression roller 29 is set to a temperature of 170 to 210 ° C. and a pressure of 0 to 40 kgf / cm 2 (excluding the self-weight pressure of the compression roller) to proceed with calendering of the porous nanofiber web 15.
  • the porous membrane can be stabilized in actual use.
  • the calendering temperature and pressure are as follows:
  • porous nanofiber web 15 having a thickness of 10 to 25 ⁇ m, that is, a porous separator is obtained.
  • the porous membrane obtained after the above calendering process is a step of removing residual solvent or water using a secondary hot air dryer 30 having a temperature of 100 ° C. and a wind speed of 20 m / sec.
  • the transfer sheet 25a is wound around the winder 31 as a winding roll of the porous separator in a state in which the transfer sheet 25a is disposed inside.
  • the obtained porous separator i.e., the nanofiber web 15 is mixed with a combination of polyvinylidene fluoride (PVdF) and polyacrylonitrile (PAN) when the swellable polymer and the non-swellable polymer are mixed to spun the mixed polymer.
  • PVdF polyvinylidene fluoride
  • PAN polyacrylonitrile
  • the nanofibers 150 spun by setting the molecular weight difference between the polymers to be above a set value have a core-shell structure.
  • the porous nanofiber web 15 constituting the porous separator of the present invention is composed of a core-shell structured nanofiber 150 surrounded by the swellable polymer shell 150a on the outside of the non-swellable polymer core 150b. do.
  • one of the positive electrode 1 and the negative electrode 3 may be encapsulated by an encapsulation process using two porous separators 15.
  • the sealing of the positive electrode 1 will be described by way of example.
  • the positive electrode 1 double-sides the slurry including the positive electrode active materials 11b and 11c to form a bi-cell (or full cell) in the strip-shaped positive electrode current collector 11a and roll-presses the plurality of unit positive electrode cells.
  • (1a-1d) forms the anode strip (1n) formed sequentially, and winding it to the reel using a winding machine (S11).
  • the negative electrode 3 is formed in a bi-cell (or full cell) structure in the same manner as the positive electrode (S11), and separated into individual unit negative electrode cells (S14), and the plurality of unit negative electrode cells 3a- as shown in FIG. Prepare 3c).
  • the anode strip 1n is blanked from the anode strip 1n by blanking (ie, punching) using a blanking equipment before winding to the reel or before the encapsulation process shown in FIG. 4 is started.
  • the plurality of unit positive electrode cells 1a-1d are partially separated, leaving portions for forming the positive electrode terminal 11x (S12).
  • each unit anode cell 1a-1d has a constant area such as a rectangle or a square. It has a rectangular shape and punches to be interconnected.
  • the pair of porous nanofiber webs 15a are disposed on the upper and lower portions of the positive electrode strip 1n and the pair of porous nanofiber webs 15a and 15b respectively stacked on the transfer sheets 15c and 15d.
  • 15b) and the positive electrode strip 1n are subjected to roll pressing with heat and pressure while continuously passing the roll pressing apparatus 33 composed of a pair of hot pressing rolls 33a and 33b (S13).
  • the pair of porous nanofiber webs 15a and 15b have a strip shape having a width wider by a predetermined length than the width of the anode strip 1n, as shown in FIG.
  • the pair of porous nanofiber webs 15a and 15b are set equal to the width of the unit cathode cells 3a-3c.
  • 11x indicates a positive terminal and 13x indicates a negative terminal.
  • the transfer sheets 15c and 15d are peeled off and removed from the porous nanofiber webs 15a and 15b as shown in FIG.
  • the pair of porous nanofiber webs 15a and 15b sequentially encapsulate a plurality of unit anode cells 1a-1d of the anode strip 1n by a roll-to-roll method.
  • the sealing can be made to have a high productivity.
  • the unit cathode cells 3a-3c are stacked between the plurality of unit anode cells 1a-1d encapsulated with the porous nanofiber web 15 to form the electrode assembly 100.
  • an electrode assembly 100 in which a plurality of unit cathode cells and a unit cathode cell are stacked in a lithium ion polymer battery has a problem that expansion and contraction occurs in the stacking direction of cells due to expansion inside thereof during charging and discharging. If this operation is repeated, the liquid electrolyte impregnated in the electrode is impregnated with the electrolyte and separation between the electrode and the electrolyte occurs. As a result, the interface resistance gradually increases, resulting in a decrease in the open circuit voltage (OCV). There is.
  • the outside of the electrode assembly 100 is taped with the thin film pressing band 101 made of a non-swellable material, so that the expansion and contraction of the electrode assembly 100 during charging and discharging proceeds. It is possible to reduce the OCV (open circuit voltage) by minimizing the increase in interfacial resistance by inducing the lateral direction instead of the vertical direction to prevent separation between the electrolyte and the electrode.
  • OCV open circuit voltage
  • a part of the swellable polymer is filled in the positive electrode 1 and the negative electrode 3 in a continuous state with the polymer electrolyte 5 so that the positive electrode 1 and the negative electrode 3 and the Adhered to the polymer electrolyte 5, the reduction of the OCV (open circuit voltage) can be minimized.
  • the pressing band 101 may be, for example, an olefin-based film such as PP / PE or PE / PP / PE nonwoven fabric or PET film available from Celgard, and a thin ceramic.
  • an olefin-based film such as PP / PE or PE / PP / PE nonwoven fabric or PET film available from Celgard, and a thin ceramic.
  • a structure in which a large capacity electrode assembly 100 is formed by stacking unit cathode cells 3a-3c between a plurality of unit anode cells 1a-1d by a Z folding method is described.
  • the present invention is not limited thereto.
  • the electrode assembly 100 may be formed and taped to the compression band 101.
  • the pressure band 101 may be taped in a state in which at least one strength reinforcing plate is assembled to one side or both sides of the electrode assembly 100.
  • unit anode cells 1a-1d instead of unit anode cells 1a-1d, a plurality of unit cathode cells 3a-3c are continuously encapsulated using a pair of porous nanofiber webs 15a, 15b, and then a plurality of unit cathodes are used.
  • the unit anode cells 1a-1d may be stacked between the cells 3a-3c to form a large electrode assembly 100.
  • porous nanofiber webs 15a and 15b may be sandwiched between the anode 1 and the cathode 3 and integrated by a heating lamination process, and then laminated or rolled to assemble into a case.
  • the anode 1 and the cathode 3 having the porous nanofiber webs 15a and 15b formed on one surface thereof. May be laminated and integrated by a heat lamination process, and then laminated or rolled to assemble into a case.
  • the electrode assembly 100 taped with the pressing band 101 is embedded in a case (not shown) (S17), and after the organic electrolyte is injected, heat treatment is performed to seal the gel (S18, S19). ).
  • the injected organic electrolytic solution is set to inject an appropriate amount in which all of the swellable polymers contained in the porous nanofiber web 15 are swelled by 300 to 500% to gelate and substantially no liquid organic solvent remains.
  • porous nanofiber webs 15a and 15b disposed between the anode 1 and the cathode 3 are porous membranes having a three-dimensional pore structure, impregnation is made very quickly when the organic electrolyte is injected.
  • the gelling process is injected after cooling the organic electrolytic solution, and then heated to a condition of 10 minutes to 600 minutes at a temperature range of 40 °C to 120 °C.
  • the swellable polymer disposed outside the nanofiber 150.
  • the shell 150a undergoes plasticization and gels, and the non-swellable polymer core 150b disposed inside maintains a matrix shape as only a slight swelling occurs and the chain is not broken.
  • the polymer electrolyte 5 forms an inorganic pore type gel electrolyte in which the liquid organic solvent does not remain substantially as a whole by the swellable polymer shell 150a formed with gelation, and at the same time, the non-swellable polymer core 150b. ) Maintains its shape without swelling in the electrolyte.
  • the gel-swellable polymer shell 150a functions as a lithium ion conductor that carries lithium ions that are oxidized or reduced at the negative electrode 3 and the positive electrode 1 during charging and discharging of the battery, and is non-swellable.
  • the polymer core 150b serves as a separator that physically isolates the positive electrode 1 and the negative electrode 3, thereby preventing short circuits between the positive electrode and the negative electrode, thereby improving safety.
  • a part of the swellable polymer swelled through the gelation process penetrates into the positive electrode 1 and the negative electrode 3, thereby decreasing the interfacial resistance between the electrode and the polymer electrolyte 5 and simultaneously The electrolyte 5 can be thinned.
  • the nanofiber 150 of the present invention having a core-shell structure has a structure in which the swellable polymer shell 150a is surrounded by the outside of the non-swellable polymer core 150b, so that the gelation process may be performed after impregnating the organic electrolyte solution.
  • the swellable polymer shell 150a disposed outside is uniformly swelled, whereby battery characteristics can be uniformly expressed with respect to the entire electrolyte membrane.
  • a single layer of porous nanofiber web 15 made of a nanofiber 15 having a core-shell structure to form a polymer electrolyte 5 as a separator the present invention is It is not limited and may be formed in a multilayer structure.
  • FIG 8 and 9 are cross-sectional views showing an example of the composite porous separator according to the present invention.
  • the composite porous separator 210 is used as a matrix and has an adhesive layer on at least one side of the porous nonwoven fabric 211 and the porous nonwoven fabric 211 having micropores. And a porous nanofiber web 213 impregnated with an electrolyte solution.
  • the porous nonwoven fabric 211 which can be used as the substrate is a nonwoven fabric made of a double structured PP / PE fiber coated with PE on the outer circumference of the PP fiber as a core, or a PET nonwoven fabric made of polyethyleneterephthalate (PET) fiber and cellulose fiber. Any one of the nonwovens may be used.
  • PET polyethyleneterephthalate
  • the porous nonwoven fabric 211 preferably has a porosity in the range of 70 to 80.
  • porous nanofiber web 13 stacked on one side of the porous nonwoven fabric 211 is inserted between the cathode and the anode (not shown) to serve as an adhesive layer that is easily bonded to the cathode when assembly is performed.
  • the porous nanofiber web 213 may be a polymer obtained by electrospinning a polymer having excellent adhesion with a negative electrode active material, for example, PVDF (polyvinylidene fluoride).
  • the porous nonwoven fabric 211 has too large pores, as shown in the separation membrane 210a of the embodiment shown in FIG. 9, the porous nanofiber web 213 is used instead of the porous nanofiber web 213 to lower the porosity. It is preferable to convert the inorganic porous polymer film to apply the ultra-thin inorganic porous film 213a.
  • the porous nanofiber web 213 and the inorganic porous film 213a are swollen in the electrolyte and are polymers capable of conducting electrolyte ions, for example, PVDF (polyvinylidene fluoride) and PEO (poly-ethylene oxide) , PMMA (polymethyl methacrylate), TPU (Thermoplastic Poly Urethane) can be used.
  • PVDF polyvinylidene fluoride
  • PEO poly-ethylene oxide
  • PMMA polymethyl methacrylate
  • TPU Thermoplastic Poly Urethane
  • the PVDF is most preferred as a polymer having a swelling property to the electrolyte and capable of conducting electrolyte ions and excellent adhesion to the negative electrode active material.
  • the PVDF may be, for example, a CTFE-based PVDF copolymer containing 15-20 wt% of CT (Chlorotrifluoroethylene) in VF (vinylidene fluoride), or an HFP system containing 4-12 wt% of HFP (hexafluoropropylene) in VF (vinylidene fluoride) More preferred is a PVDF copolymer.
  • the CTFE-based PVDF copolymer cannot produce PVDF copolymer when it contains less than 15 wt% of CTFE comonomer, and the heat resistance of the PVDF copolymer becomes poor and too soft when it contains more than 20 wt% of CTFE comonomer. There is a problem that is difficult to use as a separation membrane because of too much absorption.
  • HFP-based PVDF copolymer contains less than 4wt% of HFP comonomer, it is impossible to manufacture the PVDF copolymer, and when the HFP comonomer exceeds 12wt%, the heat resistance of the PVDF copolymer is weakened and thus used as a separator. This is a difficult problem.
  • the above CTFE based PVDF copolymer can use Solef ® 32008 in Solvay Solef ® PVDF Fluoropolymer Resins supplied by Solvay Solexis, and the HFP based PVDF copolymer can be used in Solvay Solef ® PVDF Fluoropolymer Resins in Solef ® 21216 or ARKEMA KYNAR ® PVDF Fluoropolymer You can use KYNAR FLEX LBG among the rests.
  • the CTFE-based PVDF copolymer and the HFP-based PVDF copolymer each contain CTFE or HFP when forming a copolymer, and thus, when the PVDF copolymer is used as a separator, ionic conductivity is higher than that of PVDF made of homopolymer of VF (vinylidene fluoride). There is an advantage that is improved.
  • the ultra-fine nanofibers 215 are electrospun on one side of the porous nonwoven fabric 211 using the spinning solution 221 to collect the ultrafine fibers on the porous nonwoven fabric 211 to form a porous nanofiber web.
  • the porous nanofiber web 213 forms a porous nanofiber web made of ultrafine nanofibers 215, and is formed by calendering the obtained porous nanofiber web at a temperature below the melting point of the polymer in the calender device 226.
  • the inorganic porous film 213a may be formed by first forming a porous nanofiber web 213 on one side of the porous nonwoven fabric 211, and then, at a temperature lower than a melting point of the polymer (eg, PVDF) in a subsequent process.
  • the porous nanofiber web 213 may be converted into the inorganic porous film 213a by heat-treating the surface using the heater 225.
  • the heat treatment temperature may be performed at a temperature slightly lower than the melting point of the polymer because the solvent remains in the polymer nanofiber web.
  • the average diameter of the fibers constituting the porous nanofiber web 213 has a great influence on porosity and pore size distribution.
  • the specific surface area of the fiber is increased, thereby increasing the electrolyte retention capacity, thereby reducing the possibility of electrolyte leakage.
  • the fiber diameter constituting the porous nanofiber web 213 is in the range of 0.3 ⁇ 1.5um.
  • the thickness of the porous nanofiber web 213 used to form the inorganic porous film is preferably made of an ultra-thin film in the range of 1 to 10 ⁇ m, preferably 3 to 5 ⁇ m.
  • Porous nanofiber web made of ultra-fine fibers is ultra thin, ultra-light, has a high surface area to volume ratio and high porosity.
  • the inorganic porous film 213a applied to the above embodiment is capable of conducting lithium ions while being swelled by the electrolyte when it is impregnated with the electrolyte and is composed of an ultra-thin film, and thus does not act as a resistance and increases the mobility of the lithium ions. .
  • the electrode assembly film 213a When the electrode assembly film 213a is compressed to be in close contact with the surface of the negative electrode active material layer as described above, the electrode swells by the electrolyte and conducts lithium ions, but blocks the formation of space between the negative electrode and the separator. As a result, lithium ions may be accumulated to prevent precipitation of lithium ions. As a result, dendrite formation can be suppressed on the surface of the cathode and stability can be improved.
  • the spinning solution prepared for forming the porous nanofiber web 213 by electrospinning may include a predetermined amount of inorganic particles to increase heat resistance and strength.
  • the inorganic particles and the content are applied in the same manner as when forming the porous nanofiber web 215.
  • the secondary battery of the present invention includes an electrolyte in an electrode assembly, which is assembled by pressing a separator between a negative electrode and a positive electrode.
  • the electrolyte solution includes a solute of a non-aqueous organic solvent and a lithium salt.
  • the electrolyte may be the same as that used when forming the polymer electrolyte 5 shown in FIG.
  • the electrode assembly As described above, after assembling the electrode assembly, it is placed in an aluminum or aluminum alloy can or a similar container, the opening is closed with a cap assembly, and an electrolyte is injected to manufacture a lithium secondary battery.
  • the PVDF porous nanofiber web 213 or the inorganic porous film 213a is swollen while gelling with the electrolyte.
  • the thickness of the non-porous film 213a laminated on the porous nonwoven fabric 211 is made of an ultra-thin film of 1 to 10um range, preferably 3 to 5 ⁇ m each, so that when the electrolyte is injected and impregnated, the micropores Is formed to allow the movement of lithium ions.
  • OCV characteristics can be greatly improved without micro shorts occurring.
  • the nanofibers of the nanofiber webs swell about 500 times, and the pores are reduced in size to form a film.
  • the movement of lithium ions through the micropores of the nanofiber web is possible, and the generation of micro shorts can be blocked to significantly improve the OCV characteristics.
  • the porous nonwoven fabric 211 is used as a substrate, and one side of the nonwoven fabric is made of the PVDF inorganic porous film 213a, the inorganic porous film 213a having excellent adhesion is adhered to the surface of the negative electrode and assembled. Therefore, it plays a role of suppressing dendrite formation.
  • the composite porous separator 210 may be applied to a lithium polymer battery including, for example, a positive electrode, a gel polymer electrolyte of an inorganic type, and a negative electrode, as shown in FIG. 1.
  • the polymer electrolyte uses a composite porous separator 210 in which a porous nonwoven fabric 211 and a porous nanofiber web 213 made of a plurality of nanofibers 215 are stacked.
  • the nanofiber 215 is a mixture of a swellable polymer and a non-swellable polymer mixed to form a core-shell structure surrounded by a swellable polymer shell on the outside of the non-swellable polymer core in the same manner as the nanofiber 150 shown in FIG. 1.
  • Polymer is used as spinning solution.
  • the mixed polymers are combined such that, for example, the molecular weight difference between the swellable polymer and the non-swellable polymer, such as PVDF and PAN, is at least 20 times or more.
  • the anode and the cathode are assembled.
  • the electrode assembly is cased, an electrolyte solution is injected, and gelation heat treatment is performed to form a gel polymer electrolyte between the positive electrode and the negative electrode.
  • a swelling is performed in an electrolyte and a spinning solution is prepared by dissolving a polymer capable of conducting electrolyte ions in a solvent.
  • the multi-hole nozzle pack 221 is used, for example, of the porous nonwoven fabric 11 to which the spinning solution is transported along the collector 223 on the lower side by air-electrospinning (AES).
  • AES air-electrospinning
  • Ultrafine nanofibers 215 are electrospun on one side to form a porous nanofiber web 230 to form a laminate having a two-layer structure.
  • Air electrospinning (AES) method of the present invention is ultra-fine to the collector 223 by applying a high voltage electrostatic force of 90 ⁇ 120Kv between the spinneret and the collector 223 of the multi-hole nozzle pack 221 in which the polymer solution is radiated
  • the nanofibers 215 are spun to form a porous nanofiber web 230, in this case is a spinning method that catches the flying fibers are not collected in the collector 223 by spraying air for each spinning nozzle.
  • the composite porous separator composed of the porous nonwoven fabric 211 and the porous polymer nanofiber web 213 as shown in FIG. 210 is obtained.
  • the porous nanofiber web 230 is laminated on one side of the porous nonwoven fabric 211, porous nano When the fibrous web 230 is transferred to the heater 225, the porous nanofiber web 230 is converted into the inorganic porous film 213a.
  • the composite porous separator composed of the porous nonwoven fabric 211 and the inorganic porous film 13a as shown in FIG. 210a is obtained.
  • the transfer sheet for transferring the spinning solution from the multi-hole nozzle pack 221 along the lower collector 223 using a transfer method The ultrafine nanofibers 215 are electrospun on one side of 211a to form a porous nanofiber web 230 made of ultrafine nanofibers.
  • the transfer sheet 211a may be, for example, a paper or a polyolefin-based film such as nonwoven fabric, PE, PP, or the like made of a polymer material which is not dissolved by a solvent contained therein during spinning of the spinning solution.
  • a drying process, a calendering process, and a winding process while being transferred at a high feed rate due to low tensile strength.
  • the electrospun nanofibers develop in the collector and are stacked along the pattern of the integrated part (ex. When the nanofibers are radiated onto the diamond pattern, the nanofibers begin to accumulate along the initial diamond pattern).
  • the melting point of the nonwoven fabric is limited by the control of the calendering temperature.
  • the bonding temperature between PVdF fibers is about 150 degrees, but the melting point of nonwoven fabrics is 110 to 130 degrees. Therefore, when the porous nanofiber web of nanofibers is spun onto paper, primary calendering is performed at about 150 degrees, and the nonwoven fabric is laminated by secondary calendering at a temperature lower than the primary calendering temperature. The result is a strong bond between fibers, creating a highly porous nanofiber web.
  • the paper absorbs the solvent contained in the nanofiber web to prevent the nanofibers from re-melting by the residual solvent. It can also serve to control the amount of residual solvent appropriately.
  • the porous nanofiber web 230 formed on the transfer sheet 211a is then laminated on one side of the porous nonwoven fabric 211 with the porous nanofiber web 230 obtained in a solvent remaining state, and the calender apparatus 226. It is also possible to form the composite porous separator 210 of the two-layer structure according to the embodiment by calendering in.
  • the transfer sheet 211a is peeled off and removed after the lamination process as shown in FIG. 11.
  • the spinning method usable in the preparation of the porous separator according to the present invention includes general electrospinning, electrospray, electrobrown spinning, and centrifugal electrospinning in addition to air electrospinning (AES). (centrifugal electrospinning) or flash-electrospinning can be used.
  • AES air electrospinning
  • the air pressure of the air jet is set in the range of 0.1 to 0.6 MPa when using air electrospinning (AES).
  • the solvent when using a single solvent, considering that the solvent may not be volatilized well depending on the type of polymer, it passes through a pre-air dry zone by the pre-heater 225 after the spinning process. While controlling the amount of solvent and water remaining on the surface of the porous nanofiber web may be processed.
  • Pre-heating section by pre-heater is applied to the nanofiber web by applying air of 20 ⁇ 40 °C to the nanofiber web to control the amount of solvent and moisture remaining on the surface of the porous nanofiber web.
  • the membrane having a single layer or multilayer structure made of porous nanofiber web has low tensile strength
  • the porous nonwoven fabric made of a nonwoven fabric having a relatively high tensile strength is used as a support, the tensile strength of the membrane can be increased.
  • the composite porous separators 210 and 210a have a two-layer structure in which the porous nanofiber web 213 or the inorganic porous film 213a is laminated on one side of the porous nonwoven fabric 211. Accordingly, it is also possible to have a three-layer structure in which the inorganic porous films 213a are laminated on both sides of the porous nonwoven fabric 211.
  • the nanofibers constituting the porous nanofiber web form a shell-core structure, and the outer swellable polymer shell has a uniform web shape by the non-swellable polymer core disposed inside even though gelation is performed by the electrolyte. It can be applied to a lithium ion polymer battery provided with a polymer electrolyte which can prevent short circuit between both electrodes by holding, and can simultaneously aim at safety and thinning.

Landscapes

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

Abstract

The present invention relates to a porous separation membrane in which short circuit between two electrodes can be prevented using a porous nanofiber web having nanofibers with a shell-core structure, to thereby provide safety and enable the membrane to be thin. The present invention also relates to a secondary battery using the membrane and to a method for manufacturing said secondary battery. The porous membrane of the present invention comprises: a porous non-woven fabric which serves as a support and has fine pores; and a porous nanofiber web laminated on one side of the non-woven fabric such that the porous nanofiber web serves as an adhesive layer and an ion-absorption layer when the membrane tightly contacts an opposed electrode. A portion of the porous nanofiber web is inserted into the surface layer of the porous non-woven fabric so as to partially close the pores of the porous non-woven fabric, thus lowering the air porosity of the porous non-woven fabric. The nanofiber of the porous nanofiber web may be produced by blend-spinning swelling polymers and non-swelling polymers so as to form a shell-core structure.

Description

다공성 분리막, 이를 이용한 이차전지 및 그의 제조방법Porous separator, secondary battery using same and manufacturing method thereof
본 발명은 다공성 분리막, 이를 이용한 이차전지 및 그의 제조방법에 관한 것으로, 특히 나노섬유가 팽윤성 폴리머와 비팽윤성 폴리머를 혼합 방사하여 쉘-코어 구조를 갖는 다공성 나노섬유 웹을 이용하여 두 전극 사이의 단락을 방지하여 안전성과 박막화를 동시에 도모할 수 있는 다공성 분리막, 이를 이용한 이차전지 및 그의 제조방법에 관한 것이다.The present invention relates to a porous separator, a secondary battery using the same, and a method for manufacturing the same. In particular, a short circuit between two electrodes using a porous nanofiber web having a shell-core structure by mixing and spinning a nanofiber with a swellable polymer and a non-swellable polymer The present invention relates to a porous separator, a secondary battery using the same, and a method of manufacturing the same, which can simultaneously achieve safety and thinning.
종래에, 리튬 이차 전지의 전해질로서는, 일반적으로 비수계(non-aqueous) 전해액을 세퍼레이터로 지칭되는 세공을 가진 필름에 함침시킨 전해질이 사용되었다. 최근에는, 이러한 액계의 전해질보다 폴리머로 이루어진 폴리머 전해질을 이용한 리튬 이차 전지(폴리머 전지)가 주목받고 있다.Conventionally, as an electrolyte of a lithium secondary battery, the electrolyte which impregnated the non-aqueous electrolyte solution into the film which has a pore called a separator generally was used. In recent years, attention has been paid to lithium secondary batteries (polymer batteries) using polymer electrolytes made of polymers rather than liquid electrolytes.
이러한 폴리머 전지는, 폴리머 중에 액체 전해액을 함침시킨 겔 형태의 전해질을 사용하고 있다. 폴리머 중에 전해액이 보유되기 때문에, 액이 새어나오기 어렵고, 따라서, 전지의 안전성이 향상되며, 또한 전지의 형상을 자유롭게 할 수 있는 장점이 있다.Such a polymer battery uses a gel electrolyte in which a liquid electrolyte is impregnated in a polymer. Since the electrolyte is retained in the polymer, the liquid is less likely to leak, and therefore, there is an advantage in that the safety of the battery is improved and the shape of the battery can be freed.
이러한 폴리머 전해질은 전해액으로만 이루어진 전해질에 비해, 리튬 이온의 도전성이 낮기 때문에, 폴리머 전해질의 두께를 얇게 하는 방법이 행해지고 있다. 하지만, 이와 같이 폴리머 전해질을 얇게 한 경우 그 기계적 강도가 감소되고, 전지의 제조시에 양극과 음극이 단락되어 폴리머 전해질이 파괴되기 쉬운 문제가 있다.Since the polymer electrolyte has a lower conductivity of lithium ions than an electrolyte composed only of an electrolyte solution, a method of thinning the thickness of the polymer electrolyte is performed. However, when the polymer electrolyte is thinned in this manner, its mechanical strength is reduced, and the positive electrode and the negative electrode are short-circuited at the time of battery manufacturing, and thus the polymer electrolyte is easily destroyed.
한국 등록특허 제10-0637481호에는 양극과, 폴리머 전해질과, 음극을 구비하여 이루어지고, 상기 폴리머 전해질은, 유기 전해액에 의해 겔화가 용이한 겔화 섬유와 비겔화 섬유를 적어도 가지는 부직포에 상기 유기 전해액이 함침되어 이루어져, 상기 겔화 섬유가 상기 유기 전해액을 포함하여 겔화된 상태에 있어서, 겔상태의 겔화 섬유 및 비겔화 섬유의 배합 비율은 3 : 97 내지 75 : 25 중량비이며, 비닐 아세테이트의 함유량이 5 중량% 이상 20 중량% 이하인 폴리아크릴로니트릴-비닐 아세테이트 공중합체인 리튬 이차 전지가 제안되어 있다.Korean Patent No. 10-0637481 includes an anode, a polymer electrolyte, and a cathode, wherein the polymer electrolyte is a non-woven fabric having at least a gelling fiber and a non-gelling fiber which are easily gelled by an organic electrolyte solution. When the gelled fibers are impregnated with the organic electrolyte solution, the blending ratio of the gelled fibers and the non-gelled fibers is from 3:97 to 75:25 by weight, and the vinyl acetate content is 5 Lithium secondary batteries have been proposed which are polyacrylonitrile-vinyl acetate copolymers that are at least 20% by weight.
상기 한국 등록특허 제10-0637481호에 제안된 폴리머 전해질은 겔화 섬유와 비겔화 섬유를 적어도 가지는 부직포에 유기 전해액을 함침하는 것이므로, 함침되는 유기 전해액에 의해 겔화가 이루어지는 겔화 섬유 부분의 균일성을 보장할 수 없어 균일한 이온 전도성을 보장할 수 없고 내부 쇼트 가능성도 존재하며, 부직포 형태를 갖는 것이므로 겔화가 이루어질지라도 균일한 박막화가 어렵게 된다.Since the polymer electrolyte proposed in Korean Patent No. 10-0637481 is impregnated with an organic electrolyte solution in a nonwoven fabric having at least gelled fibers and non-gelled fibers, the uniformity of the gelled fiber portion where gelation is performed by the impregnated organic electrolyte solution is ensured. Since it is impossible to guarantee uniform ion conductivity, there is a possibility of internal short, and since it has a nonwoven form, even thinning becomes difficult even if gelation is performed.
한국 등록특허 제10-1208698호에는 서로 다른 두 전극; 상기 두 전극 사이에 개재되며, 융점이 180℃ 이상인 50~70중량% 내열성 고분자 물질과 전해액에 팽윤이 일어나는 30~50중량% 팽윤성 고분자 물질의 혼합용액을 에어 전기방사(AES: Air-electrospinning)하여 얻어진 초극세 섬유상을 포함하는 내열성 초극세 섬유상 다공성 분리막; 및 전해액 또는 전해질을 포함하는 이차 전지가 제안되어 있다.Korean Patent No. 10-1208698 discloses two different electrodes; Between the two electrodes, the mixture solution of 50 ~ 70% by weight heat-resistant polymer material having a melting point of 180 ℃ or more and swelling in the electrolyte solution 30 ~ 50% by weight swellable polymer material by air electrospinning (AES: Air-electrospinning) A heat resistant ultrafine fibrous porous membrane comprising the obtained ultrafine fibrous phase; And a secondary battery including an electrolyte solution or an electrolyte has been proposed.
그러나, 한국 등록특허 10-1208698호는 내열성 고분자 물질과 팽윤성 고분자 물질의 혼합용액을 방사하여 얻어진 초극세 섬유로 이루어진 다공성 분리막을 사용할 뿐 섬유가 코어-쉘 구조를 가질 때의 이점과 코어-쉘 구조를 형성하는 조건을 인지하지 못하였다. However, Korean Patent No. 10-1208698 uses a porous separator made of ultra-fine fibers obtained by spinning a mixed solution of a heat resistant polymer material and a swellable polymer material, and shows the advantages and advantages of the core-shell structure when the fiber has a core-shell structure. The conditions to form were not recognized.
또한, 한국 공개특허 제10-2012-46092호에는 제1무기공 고분자 필름층 및 상기 제1무기공 고분자 필름층 위에 형성되며 내열성 고분자 또는 내열성 고분자와 팽윤성 고분자, 및 무기물 입자가 혼합된 혼합물의 초극세 나노섬유로 이루어진 다공성 고분자 웹층을 포함하는 내열성 분리막이 제안되어 있다. In addition, Korean Patent Laid-Open No. 10-2012-46092 discloses an ultra-fine of a mixture of a heat-resistant polymer or a heat-resistant polymer, a swellable polymer, and an inorganic particle formed on a first non-porous polymer film layer and the first non-porous polymer film layer. A heat resistant separator including a porous polymer web layer made of nanofibers has been proposed.
상기 내열성 분리막은 10 내지 60um 두께를 갖는 2층 구조의 박막이므로 인장강도가 낮아서 생산시에 취급성이 나쁘고, 제조원가가 높아서 경쟁력을 갖지 못하는 문제가 있다. 일반적으로 나노섬유는 타섬유와 비교하여 상대적 강도는 좋을 수 있지만, 절대적 강도는 약한 편이다.Since the heat resistant separator is a thin film having a 2-layer structure having a thickness of 10 to 60 um, the tensile strength is low, so handling is poor at the time of production, and there is a problem in that it is not competitive due to high manufacturing cost. In general, nanofibers may have better relative strength than other fibers, but their absolute strength is weak.
즉, 나노섬유 자체만으로 분리막을 만드는 경우, 핸들링이 가능한 수준을 만들기 위해서는 약 10g/m2 이상의 고중량이 필요하다. 그런데 이러한 고중량 분리막은 생산속도와 직결되는 팩터(factor)로서, 고원가의 원인이 된다.In other words, when the membrane is made of only nanofibers themselves, a high weight of about 10 g / m 2 or more is required to make the level of handling possible. However, such a heavy separator is a factor directly related to the production speed, which is a cause of the high price.
또한, 나노섬유는 제조 공정상 다량의 정전기를 보유하고 있어, 그 자체만으로는 핸들링이 상당히 어려운 문제가 있다. 합지 등의 복합화를 통해 정전기를 제거하는 것은 불가능하지만 취급성의 개선은 가능하다.In addition, nanofibers have a large amount of static electricity in the manufacturing process, there is a problem that handling is very difficult by itself. Although it is impossible to remove static electricity through the compounding of paper and the like, the handleability can be improved.
더욱이, 고분자 웹 분리막은 기공도가 80% 정도이므로 이온의 이동이 너무 잘 이루어지기 때문에 마이크로 쇼트가 발생하여 OCV(open circuit voltage) 저하 현상이 발생하는 문제가 있다.In addition, since the polymer web separator has a porosity of about 80%, micro-short occurs because the ions move too well, resulting in a decrease in open circuit voltage (OCV).
PP/PE나 PET 섬유로 이루어진 부직포는 기공도가 너무 높아서 그 자체만으로는 분리막으로 사용이 불가능하다. 특히, 부직포는 기공도가 70 내지 80%에 이르기 때문에 자가 방전에 의해 OCV 특성이 나쁘고, 또한 기공 편차가 크고 큰 기공이 존재하는 문제가 있다. Nonwoven fabrics made of PP / PE or PET fibers have too high porosity and cannot be used as separators by themselves. In particular, since the nonwoven fabric has a porosity of 70 to 80%, there is a problem in that pores exist that have poor OCV characteristics due to self discharge, and large pore deviations.
이러한 점을 고려하여 부직포에 무기물 입자를 바인더와 혼합하여 세라믹층을 부가함에 의해 기공도를 낮추고 내열성을 보강한 분리막은 제조공정이 복잡하고, 무기물 입자가 탈리되는 문제가 있다.In consideration of this point, a separator having low porosity and enhanced heat resistance by adding a ceramic layer by mixing inorganic particles with a binder to a nonwoven fabric has a complicated manufacturing process and has a problem in that inorganic particles are detached.
본 발명자는 전해액에 팽윤되어 겔화가 이루어지는 팽윤성 폴리머와 비팽윤성 폴리머를 혼합하여 방사된 나노섬유는 혼합되는 2 폴리머 사이의 분자량 차이가 설정값 이상일 경우 코어-쉘 구조를 갖는 것을 발견하였다. 이 경우, 분자량이 큰 비팽윤성 폴리머가 나노섬유의 코어 부분에 위치하고 분자량이 작은 팽윤성 폴리머가 v 부분에 위치하고 있다. 또한, 비팽윤성 폴리머는 팽윤성 폴리머와 비교할 때 분자량이 크기 때문에 융점도 상대적으로 높은 것으로 나타났다. The present inventors have found that the nanofibers spun by mixing a swellable polymer and a non-swellable polymer that are swollen and electrolytically in an electrolyte solution have a core-shell structure when the molecular weight difference between the two polymers to be mixed is more than a set value. In this case, the non-swellable polymer having a large molecular weight is located in the core portion of the nanofiber, and the swellable polymer having a small molecular weight is located in the v portion. In addition, the non-swellable polymer was found to have a relatively high melting point because of its high molecular weight compared to the swellable polymer.
따라서, 유기 전해액을 주입한 후, 겔화시키기 위한 열처리 공정에서 팽윤성 폴리머의 융점보다 높고 비팽윤성 폴리머의 융점보다 낮은 온도에서 겔화를 진행하면, 나노섬유의 외측에 배치되는 팽윤성 폴리머 쉘은 겔화가 이루어질지라도 내측에 배치되는 비팽윤성 폴리머 코어는 미약한 팽윤만 일어나고 체인이 끊어지지 않고 유지됨에 따라 매트릭스 형상을 유지하는 것으로 나타났다. 본 발명은 이러한 발견에 기초하여 이루어진 것이다.Therefore, after injecting the organic electrolyte, the gelation proceeds at a temperature higher than the melting point of the swellable polymer and lower than the melting point of the non-swellable polymer in the heat treatment process for gelation, even though the swellable polymer shell placed outside the nanofibers is gelated. Non-swellable polymer cores disposed inside have been shown to maintain the matrix shape as only slight swelling occurs and the chain remains unbroken. The present invention has been made based on this finding.
따라서, 본 발명은 상기한 종래기술의 문제점을 해결하고자 제안된 것으로, 그 목적은 다공성 나노섬유 웹을 구성하는 나노섬유가 쉘-코어 구조를 형성하며 외측에 배치되는 팽윤성 폴리머 쉘은 겔화가 이루어질지라도 내측에 배치되는 비팽윤성 폴리머 코어가 폴리머 전해질 막 전체에 대하여 균일하게 웹 형상을 유지함에 따라 양극과 음극 사이의 단락을 방지하여 안전성을 도모할 수 있는 폴리머 전해질을 이용한 이차전지 및 그의 제조방법을 제공하는 데 있다.Therefore, the present invention has been proposed to solve the above problems of the prior art, the object of which is that the nanofibers constituting the porous nanofiber web forms a shell-core structure and the swellable polymer shell disposed outside is gelled. Since the non-swellable polymer core disposed inside maintains the web shape uniformly with respect to the entire polymer electrolyte membrane, there is provided a secondary battery using a polymer electrolyte capable of improving safety by preventing a short circuit between the positive electrode and the negative electrode and a manufacturing method thereof. There is.
본 발명의 다른 목적은 코어-쉘 구조를 갖는 나노섬유로 이루어진 다공성 나노섬유 웹을 전해질 매트릭스로 사용하여 유기 전해액의 빠르고 균일한 전해액 함침을 보장할 수 있는 폴리머 전해질을 이용한 이차전지 및 그의 제조방법을 제공하는 데 있다.Another object of the present invention is to use a porous nanofiber web made of nanofibers having a core-shell structure as an electrolyte matrix, and a secondary battery using a polymer electrolyte capable of ensuring fast and uniform electrolyte impregnation of an organic electrolyte, and a method of manufacturing the same. To provide.
본 발명의 또 다른 목적은 다공성 전해질 매트릭스를 구성하는 나노섬유의 외곽에 배치된 팽윤성 폴리머 쉘이 모두 겔화가 이루어짐에 따라 액상의 전해액이 거의 존재하지 않는 고상의 전해질로 변환되어 누액을 방지함에 따라 안전성과 박막화와 함께 이온 전도도를 높일 수 있는 폴리머 전해질을 이용한 이차전지 및 그의 제조방법을 제공하는 데 있다.It is still another object of the present invention that all of the swellable polymer shells arranged on the periphery of the nanofibers constituting the porous electrolyte matrix are gelled to be converted into a solid electrolyte having almost no liquid electrolyte, thereby preventing leakage. The present invention provides a secondary battery using a polymer electrolyte capable of increasing ionic conductivity with a thin film and a method of manufacturing the same.
본 발명의 또 다른 목적은 전극 조립체의 외부를 비팽윤성 다공성 박막시트로 권취함에 따라 충방전 진행시에 전극 조립체가 팽창과 수축이 발생되는 형상을 억제하여 전해질과 전극 사이의 분리 현상을 방지함에 따라 계면저항의 증가를 억제할 수 있는 이차전지 및 그의 제조방법을 제공하는 데 있다.Another object of the present invention is to wrap the outside of the electrode assembly with a non-swellable porous thin film sheet to prevent the separation between the electrolyte and the electrode by inhibiting the shape of the electrode assembly expansion and contraction during charging and discharging progress The present invention provides a secondary battery capable of suppressing an increase in interfacial resistance and a method of manufacturing the same.
본 발명의 다른 목적은 지지체로 사용되는 다공성 부직포의 일측면에 박막의 무기공 필름 또는 다공성 나노섬유 웹을 부가함에 의해 공극률(기공도)을 낮추어 OCV(개방회로전압) 저하현상을 억제할 수 있는 다공성 분리막 및 이를 이용한 이차전지를 제공하는 데 있다.Another object of the present invention is to reduce the porosity (porosity) by adding a thin inorganic porous film or porous nanofiber web to one side of the porous non-woven fabric used as a support can suppress the OCV (open circuit voltage) lowering phenomenon It is to provide a porous separator and a secondary battery using the same.
본 발명의 다른 목적은 강도 지지체로 사용 가능하며 저렴한 비용으로 입수 가능한 다공성 부직포를 이용함에 따라 인장강도를 높여서 생산시에 취급성을 높일 수 있고, 박막의 무기공 필름 또는 다공성 나노섬유 웹을 적용함에 따라 제조가격을 크게 낮출 수 있는 다공성 분리막 및 이를 이용한 이차전지를 제공하는 데 있다.Another object of the present invention is to use a porous non-woven fabric which can be used as a strength support and can be obtained at low cost to increase the tensile strength and to improve handling in production, and to apply a thin inorganic porous film or a porous nanofiber web. Accordingly, the present invention provides a porous separator and a secondary battery using the same, which can significantly lower the manufacturing price.
본 발명의 제1특징에 따르면, 본 발명은 지지체 역할을 하며 미세기공을 갖는 다공성 부직포; 및 상기 다공성 부직포의 일측면에 적층되며, 대향하는 전극과 밀착될 때 접착층 및 이온함습층 역할을 하는 다공성 나노섬유 웹을 포함하며, 상기 다공성 나노섬유 웹의 일부는 다공성 부직포의 기공을 부분적으로 차단하도록 다공성 부직포의 표면층에 함입되어 다공성 부직포의 기공도를 낮추는 것을 특징으로 하는 다공성 분리막을 제공한다.According to a first aspect of the present invention, the present invention provides a porous nonwoven fabric having a micropore as a supporter; And a porous nanofiber web stacked on one side of the porous nonwoven fabric and serving as an adhesive layer and an ion-moisture layer when in close contact with an opposite electrode, and part of the porous nanofiber web partially blocks pores of the porous nonwoven fabric. It is incorporated into the surface layer of the porous nonwoven fabric to provide a porous separator, characterized in that to lower the porosity of the porous nonwoven fabric.
본 발명의 제2특징에 따르면, 본 발명은 지지체 역할을 하며 미세기공을 갖는 다공성 부직포; 및 상기 다공성 부직포의 일측면에 적층되며, 대향하는 전극과 밀착될 때 접착층 및 이온함습층 역할을 하는 무기공 필름을 포함하며, 상기 무기공 필름의 일부는 다공성 부직포의 기공을 차단하도록 다공성 부직포의 표면층에 함입되는 것을 특징으로 하는 다공성 분리막을 제공한다.According to a second aspect of the present invention, the present invention provides a porous nonwoven fabric having a micropore as a supporter; And a non-porous film laminated on one side of the porous nonwoven fabric and serving as an adhesive layer and an ion moisturizing layer when in close contact with an opposite electrode, and a portion of the non-porous film may be formed of the porous nonwoven fabric to block pores of the porous nonwoven fabric. It provides a porous separator characterized in that it is embedded in the surface layer.
상기 다공성 나노섬유 웹은 전해액에 팽윤이 이루어지며 전해질 이온의 전도가 가능한 고분자로 이루어지는 것이 바람직하다. 상기 고분자는 PVDF, PEO, PMMA, TPU 중 어느 하나일 수 있다. The porous nanofiber web is preferably made of a polymer that swells in the electrolyte and is capable of conducting electrolyte ions. The polymer may be any one of PVDF, PEO, PMMA, and TPU.
또한, 상기 고분자는 CTFE(Chlorotrifluoroethylene)계 PVDF 공중합물 또는 HFP(hexafluoropropylene)계 PVDF 공중합물인 것이 바람직하다. 이 경우, 상기 CTFE계 PVDF 공중합물은 VF(vinylidene fluoride)에 CTFE를 15 내지 20wt% 함유하며, HFP계 PVDF 공중합물은 VF에 HFP를 4 내지 12wt% 함유하는 것이 바람직하다.In addition, the polymer is preferably a CTFE (Chlorotrifluoroethylene) PVDF copolymer or HFP (hexafluoropropylene) PVDF copolymer. In this case, the CTFE-based PVDF copolymer may contain 15 to 20 wt% of CTFE in VF (vinylidene fluoride), and the HFP-based PVDF copolymer may contain 4 to 12 wt% of HFP in VF.
상기 다공성 나노섬유 웹의 두께는 1 내지 10um 범위로 설정되고, 상기 다공성 부직포의 두께는 10 내지 40um 범위로 설정되는 것이 바람직하다.The thickness of the porous nanofiber web is set to a range of 1 to 10um, the thickness of the porous nonwoven fabric is preferably set to a range of 10 to 40um.
또한, 상기 다공성 부직포는 코어로서 PP 섬유의 외주에 PE가 코팅된 이중 구조의 PP/PE 섬유로 이루어진 부직포, 폴리에틸렌테레프탈레이트(PET) 섬유로 이루어진 PET 부직포, 셀룰로즈 섬유로 이루어진 부직포 중 어느 하나일 수 있다.In addition, the porous nonwoven fabric may be any one of a nonwoven fabric made of a double structure PP / PE fiber coated with PE on the outer circumference of the PP fiber as a core, a PET nonwoven fabric made of polyethylene terephthalate (PET) fiber, and a nonwoven fabric made of cellulose fiber. have.
상기 다공성 나노섬유 웹은 각각 길이방향을 따라 쉘-코어 구조를 이루는 다수의 나노섬유를 포함하며, 상기 다수의 나노섬유 각각은 외측에 배치되며 유기 전해액에 팽윤이 이루어지는 팽윤성 폴리머로 이루어지는 팽윤성 폴리머 쉘과 비팽윤성 폴리머로 이루어진 비팽윤성 폴리머 코어를 포함하는 것이 바람직하다.The porous nanofiber web includes a plurality of nanofibers each having a shell-core structure along a longitudinal direction, each of the plurality of nanofibers is disposed on the outside and swellable polymer shell made of a swellable polymer swelling in the organic electrolyte; It is preferred to include a non-swellable polymer core made of a non-swellable polymer.
이 경우, 상기 팽윤성 폴리머와 비팽윤성 폴리머 사이의 분자량 차이가 20배 이상인 것이 바람직하다.In this case, it is preferable that the molecular weight difference between the swellable polymer and the non-swellable polymer is 20 times or more.
또한, 상기 다공성 나노섬유 웹은 40~90중량% 비팽윤성 폴리머와 10~60중량%의 팽윤성 폴리머를 포함하는 것이 바람직하다.In addition, the porous nanofiber web preferably comprises 40 to 90% by weight non-swellable polymer and 10 to 60% by weight of swellable polymer.
본 발명의 제3특징에 따르면, 본 발명은 양극, 음극, 상기 양극과 음극을 분리시키는 분리막 및 전해액을 포함하며, 상기 분리막은 지지체 역할을 하며 미세기공을 갖는 다공성 부직포; 및 상기 다공성 부직포의 일측면에 적층되며, 대향하는 전극과 밀착될 때 접착층 및 이온함습층 역할을 하는 다공성 나노섬유 웹을 포함하며, 상기 다공성 나노섬유 웹의 일부는 다공성 부직포의 기공을 부분적으로 차단하도록 다공성 부직포의 표면층에 함입되어 다공성 부직포의 기공도를 낮추는 것을 특징으로 하는 이차전지를 제공한다.According to a third aspect of the present invention, the present invention includes a positive electrode, a negative electrode, a separator for separating the positive electrode and the negative electrode and the electrolyte, the separator is a porous non-woven fabric that serves as a support and has micropores; And a porous nanofiber web stacked on one side of the porous nonwoven fabric and serving as an adhesive layer and an ion-moisture layer when in close contact with an opposite electrode, and part of the porous nanofiber web partially blocks pores of the porous nonwoven fabric. It is embedded in the surface layer of the porous nonwoven fabric to provide a secondary battery characterized in that to lower the porosity of the porous nonwoven fabric.
이 경우, 상기 다공성 나노섬유 웹은 전해액에 팽윤이 이루어지며 전해질 이온의 전도가 가능한 고분자로 이루어지며, 상기 고분자는 CTFE계 PVDF 공중합물 또는 HFP계 PVDF 공중합물인 것이 바람직하다.In this case, the porous nanofiber web is made of a polymer that swells in the electrolyte and is capable of conducting electrolyte ions, and the polymer is preferably a CTFE PVDF copolymer or an HFP PVDF copolymer.
또한, 상기 다공성 나노섬유 웹은 각각 길이방향을 따라 쉘-코어 구조를 이루는 다수의 나노섬유를 포함하며, 상기 다수의 나노섬유 각각은 외측에 배치되며 전해액에 팽윤이 이루어지는 팽윤성 폴리머로 이루어지는 팽윤성 폴리머 쉘과 비팽윤성 폴리머로 이루어진 비팽윤성 폴리머 코어를 포함할 수 있다.In addition, the porous nanofiber web includes a plurality of nanofibers each forming a shell-core structure along the longitudinal direction, each of the plurality of nanofibers are disposed on the outside and swellable polymer shell made of a swellable polymer swelling in the electrolyte solution And a non-swellable polymer core made of a non-swellable polymer.
더욱이, 상기 다공성 나노섬유 웹은 리튬염이 비수성 유기용매에 용해된 전해액에 함침된 후, 겔화 공정이 이루어짐에 따라 상기 나노섬유의 외측에 배치되는 팽윤성 폴리머 쉘은 전해액에 의해 겔화가 이루어지고, 내측에 배치되는 비팽윤성 폴리머 코어는 웹 형상을 유지하는 것이 바람직하다. Furthermore, the porous nanofiber web is impregnated with an electrolyte solution in which a lithium salt is dissolved in a non-aqueous organic solvent, and as a gelation process is performed, the swellable polymer shell disposed outside the nanofiber is gelled by an electrolyte solution. Preferably, the non-swellable polymer core disposed inside maintains the web shape.
이 경우, 상기 다공성 나노섬유 웹은 겔화 공정이 이루어짐에 따라 폴리머 전해질을 형성한다. 상기 이차전지에서 양극과 음극은 각각 교대로 적층되는 다수의 단위 전극셀로 이루어지고, 상기 폴리머 전해질로 분리되며, 상기 폴리머 전해질에 의해 분리되어 적층된 다수의 양극 및 음극 단위 셀이 적층방향으로 팽창되는 것을 차단하기 위한 압박밴드를 더 포함하는 것이 바람직하다.In this case, the porous nanofiber web forms a polymer electrolyte as the gelation process is performed. In the secondary battery, the positive electrode and the negative electrode each include a plurality of unit electrode cells stacked alternately, separated into the polymer electrolyte, and the plurality of positive and negative electrode unit cells separated and stacked by the polymer electrolyte are expanded in the stacking direction. It is preferable to further include a compression band for blocking the thing.
본 발명의 제4특징에 따르면, 본 발명은 각각 비팽윤성 폴리머와 팽윤성 폴리머로 이루어진 다수의 나노섬유를 구비하는 한쌍의 다공성 나노섬유 웹을 사용하여 다수의 단위 양극셀과 다수의 단위 음극셀을 분리하면서 교대로 적층된 전극 조립체; 상기 전극 조립체의 외주를 테이핑하는 압박밴드; 및 상기 압박밴드로 테이핑된 전극 조립체를 내장하며, 전해액이 주입된 케이스를 포함하며, 겔화 공정이 이루어짐에 따라 상기 나노섬유의 외측에 배치되는 팽윤성 폴리머 쉘은 전해액에 의해 겔화가 이루어지고, 내측에 배치되는 비팽윤성 폴리머 코어는 웹 형상을 유지하는 것을 특징으로 하는 이차전지를 제공한다.According to a fourth aspect of the present invention, the present invention separates a plurality of unit cathode cells and a plurality of unit cathode cells using a pair of porous nanofiber webs each including a plurality of nanofibers each composed of a non-swellable polymer and a swellable polymer. Alternately stacked electrode assemblies; A compression band taping the outer circumference of the electrode assembly; And an electrode assembly taped by the compression band, and including a case in which an electrolyte is injected, and a swellable polymer shell disposed outside of the nanofibers is gelled by an electrolyte as the gelation process is performed. The non-swellable polymer core that is disposed provides a secondary battery characterized by maintaining a web shape.
본 발명의 제5특징에 따르면, 본 발명은 팽윤성 폴리머와 비팽윤성 폴리머를 용매에 용해시켜 혼합 폴리머 방사용액을 형성하는 단계; 상기 혼합 폴리머 방사용액을 방사하여 상기 팽윤성 폴리머와 비팽윤성 폴리머가 쉘-코어 구조를 형성하는 다수의 나노섬유로 이루어진 다공성 나노섬유 웹을 형성하는 단계; 각각 다수의 단위 전극셀로 이루어지는 양극과 음극 사이에 상기 다공성 나노섬유 웹을 삽입하여 전극 조립체를 형성하는 단계; 상기 전극 조립체를 케이스에 내장하고 전해액을 주입하는 단계; 및 겔화 열처리를 실시하여, 상기 나노섬유의 외측에 배치되는 팽윤성 폴리머 쉘을 전해액에 의해 팽윤시키는 단계를 포함하며, 상기 나노섬유의 내측에 배치되는 비팽윤성 폴리머 코어는 웹 형상을 유지하는 것을 특징으로 하는 이차전지의 제조방법을 제공한다.According to a fifth aspect of the invention, the present invention comprises the steps of dissolving the swellable polymer and the non-swellable polymer in a solvent to form a mixed polymer spinning solution; Spinning the mixed polymer spinning solution to form a porous nanofiber web composed of a plurality of nanofibers in which the swellable polymer and the non-swellable polymer form a shell-core structure; Forming an electrode assembly by inserting the porous nanofiber web between an anode and a cathode each consisting of a plurality of unit electrode cells; Embedding the electrode assembly in a case and injecting an electrolyte solution; And performing a gelling heat treatment to swell the swellable polymer shell disposed on the outside of the nanofibers with an electrolyte solution, wherein the non-swellable polymer core disposed on the inside of the nanofibers maintains a web shape. It provides a secondary battery manufacturing method.
이 경우, 상기 다공성 나노섬유 웹은 상기 혼합 폴리머 방사용액을 스트립형 트랜스퍼 시트에 방사하여 형성되며, 상기 전극 조립체를 형성하는 단계는 상기 다수의 단위 전극셀을 연속적으로 이송하면서 양면에 한쌍의 다공성 나노섬유 웹으로 봉지하는 단계; 및 상기 봉지 단계 이후에 한쌍의 다공성 나노섬유 웹으로부터 트랜스퍼 시트를 각각 분리시키는 단계를 더 포함할 수 있다.In this case, the porous nanofiber web is formed by spinning the mixed polymer spinning solution on a strip-shaped transfer sheet, the forming of the electrode assembly is a pair of porous nano on both sides while continuously transporting the plurality of unit electrode cells Encapsulating with a fibrous web; And separating the transfer sheets from the pair of porous nanofiber webs after the encapsulation step, respectively.
상기한 바와 같이, 본 발명에서는 전해액에 팽윤되어 겔화가 이루어지는 팽윤성 폴리머와 비팽윤성 폴리머를 혼합하여 방사된 나노섬유에 의해 형성된 나노섬유 웹을 다공성 분리막으로 사용하여 유기 전해액이 함침됨에 따라 균일한 전해액 함침을 보장할 수 있다.As described above, in the present invention, by using the nanofiber web formed by the nanofibers swelled and mixed with the non-swellable polymer, which swells in the electrolyte and gels, it is impregnated with a uniform electrolyte solution as the organic electrolyte is impregnated. Can be guaranteed.
또한, 본 발명에서는 다공성 나노섬유 웹을 구성하는 나노섬유가 쉘-코어 구조를 형성함에 따라 외측에 배치되는 팽윤성 폴리머 쉘은 겔화가 이루어질지라도 내측에 배치되는 비팽윤성 폴리머 코어가 폴리머 전해질 막 전체에 대하여 균일하게 웹 형상을 유지함에 따라 양극과 음극 사이의 단락을 방지하여 안전성을 도모함과 동시에 리튬의 덴드라이트 결정 석출에 의한 쇼트의 발생을 방지할 수 있게 된다.In addition, in the present invention, as the nanofibers constituting the porous nanofiber web form a shell-core structure, the non-swellable polymer core disposed on the inside of the swellable polymer shell disposed on the outside with respect to the entire polymer electrolyte membrane, even if gelation occurs. By maintaining the web shape uniformly, short circuits between the positive electrode and the negative electrode can be prevented, and safety can be prevented, and at the same time, occurrence of short due to precipitation of dendrite crystals of lithium can be prevented.
더욱이, 다공성 분리막에서 웹 형상을 유지하는 비팽윤성 폴리머 코어가 양극과 음극의 사이에 잔존하기 때문에, 양, 음극에 충전된 팽윤성 폴리머 쉘 만큼 폴리머 전해질 자체를 얇게 할 수 가 있고 균일한 함침에 의해 양극과 음극 사이의 이온 전도도를 높일 수 있게 된다.Furthermore, since the non-swellable polymer core that maintains the web shape in the porous separator remains between the positive electrode and the negative electrode, the polymer electrolyte itself can be made as thin as the swellable polymer shell filled in the positive and negative electrodes, and the positive electrode is uniformly impregnated. It is possible to increase the ionic conductivity between the cathode and the cathode.
본 발명에서는 폴리머 전해질의 외측에 박막의 접착층을 구비함에 따라 양극 또는 음극과의 접착성을 개선함과 동시에 리튬의 덴드라이트 성장에 의한 쇼트를 방지할 수 있게 된다.In the present invention, by providing the adhesive layer of the thin film on the outer side of the polymer electrolyte, it is possible to improve the adhesion with the positive electrode or the negative electrode and to prevent the short circuit due to the growth of lithium dendrites.
또한, 본 발명에서는 전극 조립체의 외부를 비팽윤성 박막 밴드로 테이핑함에 따라 충방전 진행시에 전극 조립체의 팽창과 수축이 전극 조립체의 수직방향 대신에 측면방향으로 이루어지도록 유도하여 전해질과 전극 사이의 분리 현상을 방지함에 따라 계면저항의 증가를 억제할 수 있어, OCV(Open Circuit Voltage: 개방회로전압)의 감소를 최소화할 수 있다.In addition, in the present invention, by taping the outside of the electrode assembly with a non-swellable thin film band, the expansion and contraction of the electrode assembly is induced in the lateral direction instead of the vertical direction of the electrode assembly during charging and discharging to separate the electrolyte and the electrode. By preventing the phenomenon, it is possible to suppress the increase in the interfacial resistance, thereby minimizing the reduction of the open circuit voltage (OCV).
더욱이, 본 발명에서는 상기 팽윤성 폴리머의 일부가 상기 폴리머 전해질과 연속한 상태로 상기 양극 및 상기 음극에 충전되는 것에 의해 상기 양극 및 음극과 상기 폴리머 전해질과 접착되어, OCV(개방회로전압)의 감소를 최소화할 수 있다.Furthermore, in the present invention, part of the swellable polymer is adhered to the positive electrode and the negative electrode and the polymer electrolyte by being charged to the positive electrode and the negative electrode in a continuous state with the polymer electrolyte, thereby reducing the OCV (open circuit voltage). It can be minimized.
본 발명에서는 지지체로 사용되는 다공성 부직포의 일측면에 초박막의 무기공 필름 또는 다공성 나노섬유 웹을 부가함에 의해 공극률(기공도)을 낮추어 마이크로 쇼트가 발생하지 않으며 OCV 저하현상을 억제할 수 있다.In the present invention, by adding an ultra-thin inorganic porous film or porous nanofiber web to one side of the porous nonwoven fabric used as the support, micro shorts are not generated by reducing the porosity (porosity), and the OCV degradation phenomenon can be suppressed.
또한, 본 발명에서는 강도 지지체로 사용 가능하며 저렴한 비용으로 입수 가능한 다공성 부직포를 이용함에 따라 인장강도를 높여서 생산시에 취급성을 높일 수 있고, 초박막의 무기공 필름 또는 다공성 나노섬유 웹을 적용함에 따라 제조가격을 크게 낮출 수 있다.In addition, in the present invention, by using a porous nonwoven fabric which can be used as a strength support and can be obtained at low cost, the tensile strength can be increased to improve handling in production, and by applying an ultra-thin inorganic porous film or a porous nanofiber web, The manufacturing price can be significantly lowered.
더욱이, 본 발명에서는 전해액에 팽윤이 이루어지며 전해질 이온의 전도가 가능한 고분자를 다공성 부직포 위에 직접 전기방사하여 초박막의 무기공 필름 또는 다공성 나노섬유 웹의 일부가 부직포의 일측 표면에 함입되어 형성됨에 의해 전해액 함침 능력과 접착성이 우수하며 박막 형태의 복합 다공성 분리막을 제공할 수 있다.Furthermore, in the present invention, the electrolytic solution is formed by swelling the electrolyte and electrospinning a polymer capable of conducting electrolyte ions directly onto the porous nonwoven fabric so that a part of the ultra-thin inorganic porous film or the porous nanofiber web is formed on one surface of the nonwoven fabric. Excellent impregnation ability and adhesiveness can provide a composite porous membrane in the form of a thin film.
또한, 본 발명의 다공성 분리막은 지지체로 사용되는 다공성 부직포의 일 측면에 초박막의 무기공 필름 또는 다공성 나노섬유 웹을 적층 형성함에 의해 전극과의 밀착성을 강화하여 조립 공정 중에 발생하는 분리막의 이탈 또는 벗겨짐 등을 방지하여 이차전지의 안전성 향상 및 성능 저하 방지를 도모할 수 있다.In addition, the porous separator of the present invention by strengthening the adhesion to the electrode by forming an ultra-thin inorganic porous film or porous nanofiber web on one side of the porous non-woven fabric used as a support to remove or peel off the separation membrane generated during the assembly process Etc., it is possible to improve the safety of the secondary battery and to prevent degradation of performance.
본 발명의 다공성 분리막은 초박막의 무기공 필름 또는 다공성 나노섬유 웹을 부직포 등과 합지하는 경우 강도 보완의 효과와 함께, 합지를 통해 저중량의 나노섬유로도 가치 있는 제품을 구현할 수 있게 함으로써 나노섬유의 대량화, 저원가에 기여할 수 있다.The porous separator of the present invention, when laminating an ultra-thin inorganic porous film or porous nanofiber web with a nonwoven fabric and the like, improves the strength of the nanofibers by making it possible to realize valuable products even with low-weight nanofibers through lamination. This can contribute to low costs.
도 1은 본 발명의 바람직한 제1실시예에 따른 리튬 이차 전지를 나타내는 단면도,1 is a cross-sectional view showing a lithium secondary battery according to a first embodiment of the present invention;
도 2는 본 발명의 바람직한 제2실시예에 따른 리튬 이차 전지를 나타내는 단면도,2 is a cross-sectional view showing a rechargeable lithium battery according to a second embodiment of the present invention;
도 3은 본 발명에 따른 폴리머 전해질로 이용되는 다공성 분리막의 제조공정을 나타내는 공정 단면도,3 is a cross-sectional view illustrating a process of manufacturing a porous separator used as a polymer electrolyte according to the present invention;
도 4은 본 발명에 따른 양극과 폴리머 전해질로 사용되는 다공성 분리막의 봉지공정을 나타내는 공정 단면도,4 is a cross-sectional view illustrating a sealing process of a porous separator used as a positive electrode and a polymer electrolyte according to the present invention;
도 5는 본 발명에 따라 조립된 전극 조립체의 개략 단면도,5 is a schematic cross-sectional view of an electrode assembly assembled according to the present invention;
도 6은 본 발명에 따라 조립된 전극 조립체의 개략 평면도,6 is a schematic plan view of an electrode assembly assembled according to the present invention;
도 7은 본 발명에 따른 리튬 이차 전지의 조립 공정을 나타내는 흐름도,7 is a flowchart illustrating an assembly process of a lithium secondary battery according to the present invention;
도 8은 본 발명에 따른 복합 다공성 분리막의 단면도,8 is a cross-sectional view of the composite porous separator according to the present invention,
도 9는 본 발명에 따른 복합 다공성 분리막의 단면도,9 is a cross-sectional view of the composite porous separator according to the present invention,
도 10은 본 발명에 따른 복합 다공성 분리막을 제조하는 제조공정도10 is a manufacturing process diagram for manufacturing a composite porous separator according to the present invention
도 11은 본 발명에 따른 복합 다공성 분리막을 제조하는 변형된 제조공정도이다. 11 is a modified manufacturing process chart for manufacturing a composite porous separator according to the present invention.
상술한 목적, 특징 및 장점은 첨부된 도면을 참조하여 상세하게 후술되어 있는 상세한 설명을 통하여 더욱 명확해 질 것이며, 그에 따라 본 발명이 속하는 기술분야에서 통상의 지식을 가진 자가 본 발명의 기술적 사상을 용이하게 실시할 수 있을 것이다. The above objects, features, and advantages will become more apparent from the following detailed description with reference to the accompanying drawings, and as such, those skilled in the art to which the present invention pertains may share the spirit of the present invention. It will be easy to implement.
또한, 본 발명을 설명함에 있어서 본 발명과 관련된 공지 기술에 대한 구체적인 설명이 본 발명의 요지를 불필요하게 흐릴 수 있다고 판단되는 경우에 그 상세한 설명을 생략하기로 한다. In addition, in describing the present invention, when it is determined that the detailed description of the known technology related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted.
이하, 본 명세서에서 폴리머 전해질은 다공성 분리막 또는 다공성 나노섬유 웹을 양극 및 음극과 함께 케이스 내부에 조립한 후, 유기 전해액을 케이스에 주입함에 따라 다공성 분리막 내에 유기 전해액이 함입된 후 겔화 공정을 거쳐서 얻어지며 액상의 유기 용매가 실질적으로 잔류하지 않는 무기공 타입의 겔형 폴리머 전해질을 말한다. 폴리머 전해질을 형성하는 데 사용되는 다공성 분리막이 단층의 나노섬유 웹으로 이루어지는 경우, 나노섬유 웹은 다공성 분리막을 의미하는 것으로 사용될 수 있다.Hereinafter, in the present specification, the polymer electrolyte is obtained by assembling a porous separator or a porous nanofiber web together with a positive electrode and a negative electrode inside a case, and then injecting the organic electrolyte into the case and incorporating the organic electrolyte into the porous separator and then performing a gelation process. It refers to a gel polymer electrolyte of an inorganic pore type in which a liquid organic solvent does not substantially remain. When the porous separator used to form the polymer electrolyte is composed of a single layer of nanofiber web, the nanofiber web may be used to mean a porous separator.
첨부된 도 1은 본 발명의 바람직한 제1실시예에 따른 리튬 이차 전지를 나타내는 단면도, 도 2는 본 발명의 바람직한 제2실시예에 따른 리튬 이차 전지를 나타내는 단면도이다.1 is a cross-sectional view illustrating a lithium secondary battery according to a first preferred embodiment of the present invention, and FIG. 2 is a cross-sectional view illustrating a lithium secondary battery according to a second preferred embodiment of the present invention.
도 1을 참고하면, 본 발명의 바람직한 제1실시예에 따른 리튬 이차 전지, 즉 리튬 폴리머 전지는 풀셀(full cell)을 형성하도록 양극(1), 무기공 타입의 겔형 폴리머 전해질(5), 및 음극(3)을 구비하여 이루어진다.Referring to FIG. 1, a lithium secondary battery according to a first preferred embodiment of the present invention, that is, a lithium polymer battery, includes a cathode 1, an inorganic pore-type gel polymer electrolyte 5, and a full cell. A cathode 3 is provided.
상기 양극(1)은 양극 집전체(11a)의 일면에 양극 활물질층(11b)을 구비하고 있고, 음극(3)은 음극 집전체(13a)의 일면에 음극 활물질층(13b)을 구비하고 있다.The positive electrode 1 has a positive electrode active material layer 11b on one surface of the positive electrode current collector 11a, and the negative electrode 3 has a negative electrode active material layer 13b on one surface of the negative electrode current collector 13a. .
그러나, 상기 양극(1)은 음극(3)과 대향하여 배치되며 바이셀을 형성하도록 양극집전체(11a)의 양면에 한쌍의 양극 활물질층을 구비할 수 있다. However, the positive electrode 1 may be disposed to face the negative electrode 3 and include a pair of positive electrode active material layers on both sides of the positive electrode current collector 11a to form a bicell.
상기 양극 활물질층(11b)은 리튬 이온을 가역적으로 인터칼레이션 및 디인터칼레이션할 수 있는 양극 활물질을 포함하며, 이러한 양극 활물질의 대표적인 예로는, LiCoO2, LiNiO2, LiNiCoO2, LiMn2O4, LiFeO2, V2O5, V6O13, TiS, MoS, 또는 유기디설파이드 화합물이나 유기폴리설파이드 화합물 등의 리튬을 흡장, 방출이 가능한 물질을 사용할 수 있다. 그러나, 본 발명에서는 상기 양극 활물질 이외에도 다른 종류의 양극 활물질을 사용하는 것도 물론 가능하다. The cathode active material layer 11b includes a cathode active material capable of reversibly intercalating and deintercalating lithium ions. Representative examples of the cathode active material include LiCoO 2 , LiNiO 2 , LiNiCoO 2 , and LiMn 2 O. A substance capable of occluding and releasing lithium such as 4 , LiFeO 2 , V 2 O 5 , V 6 O 13 , TiS, MoS, or an organic disulfide compound or an organic polysulfide compound can be used. However, in the present invention, it is of course possible to use other types of positive electrode active materials in addition to the positive electrode active material.
상기 음극 활물질층(13b)은 리튬 이온을 인터칼레이션 및 디인터칼레이션할 수 있는 음극 활물질을 포함하며, 이러한 음극 활물질로는 결정질 또는 비정질의 탄소, 탄소 섬유, 또는 탄소 복합체의 탄소계 음극 활물질, 주석 산화물, 이들을 리튬화한 것, 리튬, 리튬합금 및 이들의 혼합물로 구성된 군에서 선택될 수 있다. 그러나, 본 발명은 상기 음극 활물질로 종류가 한정되는 것은 아니다. The negative electrode active material layer 13b includes a negative electrode active material capable of intercalating and deintercalating lithium ions, and the negative electrode active material includes a carbon-based negative electrode active material of crystalline or amorphous carbon, carbon fiber, or carbon composite material. , Tin oxides, lithiated ones thereof, lithium, lithium alloys and mixtures thereof. However, the present invention is not limited to the type of the negative electrode active material.
상기 양극(1) 및 음극(3)은 종래의 리튬 이온 전지에서 일반적으로 사용하던 방법과 같이 적당량의 활물질, 도전제, 결합제 및 유기 용매를 혼합하여 슬러리를 제조한 다음, 양극 및 음극 집전체(11a,13a)로서 알루미늄 또는 구리 박판(foil) 또는 메쉬 등의 양면에 제조된 슬러리를 캐스팅하고, 건조 및 압연하여 얻어질 수 있다. The positive electrode 1 and the negative electrode 3 prepare a slurry by mixing an appropriate amount of an active material, a conductive agent, a binder, and an organic solvent, as in the method generally used in a conventional lithium ion battery, and then prepare a positive electrode and a negative electrode current collector ( 11a, 13a) can be obtained by casting, drying and rolling the prepared slurry on both sides of aluminum or copper foil or mesh.
예를 들어, 양극은 활물질, 도전제, 결합제로서 LiCoO2, 수퍼-P 카본, PVdF로 구성된 슬러리를 알루미늄 호일에 캐스팅하여 사용하고, 음극으로는 MCMB(mesocarbon microbeads), 수퍼-P 카본, PVdF로 구성된 슬러리를 구리 호일에 캐스팅하여 사용할 수 있다. 상기 양극과 음극에 있어서, 슬러리를 각각 캐스팅한 후, 입자 간 및 금속 호일과의 접착력을 증대시키기 위하여 롤 프레싱을 실시하는 것이 바람직하다.For example, the positive electrode is used by casting a slurry composed of LiCoO 2 , super-P carbon, PVdF as an active material, a conductive agent, a binder on an aluminum foil, and the negative electrode is MCMB (mesocarbon microbeads), super-P carbon, PVdF The constructed slurry can be cast and used on copper foil. In the positive electrode and the negative electrode, after the slurry is cast, it is preferable to perform roll pressing in order to increase the adhesion between the particles and the metal foil.
상기 폴리머 전해질(5)은, 전해액에 팽윤되어 겔화가 이루어지는 팽윤성 폴리머와 비팽윤성 폴리머를 혼합하여 방사된 것으로 코어-쉘 구조를 갖는 나노섬유(150)로 이루어진 다공성 나노섬유 웹(15), 즉 다공성 분리막에 유기 전해액이 함입되어 겔화 열처리 공정을 거침에 따라 얻어진 것이다. The polymer electrolyte 5 is a porous nanofiber web 15 made of nanofibers 150 having a core-shell structure, that is, spun with a swellable polymer and a non-swellable polymer that are swollen in an electrolyte and gelled, that is, porous It was obtained by incorporating an organic electrolyte solution into the separator and subjecting it to a gelation heat treatment step.
다공성 나노섬유 웹(15)은 유기 전해액에 팽윤되어 겔화가 이루어지는 팽윤성 폴리머와 비팽윤성 폴리머가 혼합된 혼합물을 용매에 용해시켜 방사용액을 형성한 후, 방사용액을 방사하여 초극세 나노섬유를 포집함에 의해 다공성 나노섬유 웹을 형성하고, 고분자의 융점 이하의 온도에서 캘린더링하여 다공성 분리막이 형성된다.The porous nanofiber web 15 is formed by dissolving a mixture of a swellable polymer and a non-swellable polymer that swell in an organic electrolyte solution in a solvent to form a spinning solution, and then spinning a spinning solution to collect ultrafine nanofibers. A porous nanofiber web is formed, and a porous separator is formed by calendering at a temperature below the melting point of the polymer.
이 경우, 상기 방사용액에는 내열성을 강화하기 위하여 무기물 입자가 소정량 포함될 수 있다.In this case, the spinning solution may contain a predetermined amount of inorganic particles to enhance heat resistance.
또한, 상기 혼합물이 팽윤성 폴리머와 비팽윤성 폴리머 및 무기물 입자로 이루어지는 경우, 팽윤성 폴리머와 비팽윤성 폴리머는 4:6 내지 1:9 범위의 중량비, 바람직하게는 5:5 내지 3:7 범위의 중량비로 혼합되는 것이 바람직하다. Further, when the mixture consists of swellable polymers, non-swellable polymers and inorganic particles, the swellable polymers and non-swellable polymers may be present in a weight ratio ranging from 4: 6 to 1: 9, preferably in a weight ratio ranging from 5: 5 to 3: 7. It is preferable to mix.
상기 팽윤성 폴리머와 비팽윤성 폴리머의 혼합비가 중량비로 4:6보다 작은 경우 리튬 이온 전도도는 증가하나 팽윤성 폴리머의 팽윤 특성이 너무 커지고 양극(1) 및 음극(3)을 물리적으로 격리하는 세퍼레이터로서 역할을 하는 비팽윤성 폴리머의 양이 적게 되어 내열성과 강도가 떨어지게 된다. 즉, 유기 전해액을 함침한 후 겔화 공정을 거치게 될 때 외측에 배치된 팽윤성 폴리머 쉘(150a)이 팽윤이 되어, 내측에 배치된 비팽윤성 폴리머 코어(150b)가 폴리머 전해질 막 전체에 대하여 균일하게 웹 형상을 유지하기 어렵고, 그 결과 비팽윤성 폴리머 코어(150b)가 세퍼레이터로서 역할을 하지 못함에 따라 양극과 음극 사이의 단락을 방지하여 안전성을 도모하기 어렵게 된다.When the mixing ratio of the swellable polymer and the non-swellable polymer is smaller than 4: 6, the lithium ion conductivity is increased, but the swelling property of the swellable polymer becomes too large and serves as a separator that physically isolates the positive electrode 1 and the negative electrode 3. The amount of non-swellable polymer is reduced, resulting in poor heat resistance and strength. That is, when the gelation process is impregnated after impregnating the organic electrolyte, the swellable polymer shell 150a disposed on the outside becomes swollen, and the non-swellable polymer core 150b disposed on the inside uniformly covers the entire web of the polymer electrolyte membrane. It is difficult to maintain the shape, and as a result, as the non-swellable polymer core 150b does not function as a separator, short circuit between the positive electrode and the negative electrode is prevented, thereby making it difficult to achieve safety.
또한, 팽윤성 폴리머와 비팽윤성 폴리머의 혼합비가 중량비로 1:9보다 큰 경우 전해액의 함침이 잘 안되고 팽윤성 폴리머의 팽윤이 이루어질지라도 팽윤된 폴리머의 양이 작기 때문에 웹의 기공을 막을 수 없고 리튬 이온 전도도가 감소함과 동시에 방사성이 나빠서 방사 트러블이 발생하게 된다.In addition, if the mixing ratio of the swellable polymer and the non-swellable polymer is greater than 1: 9 by weight ratio, even if the electrolyte is not impregnated well and the swellable polymer is swelled, the amount of the swollen polymer is small and the pores of the web cannot be blocked and the lithium ion conductivity At the same time decreases the radioactivity and radiation problems occur.
다공성 나노섬유 웹(15)은 팽윤성 폴리머와 비팽윤성 폴리머를 혼합하여 혼합 폴리머를 방사하는 경우, 방사된 나노섬유(150)는 혼합되는 2 폴리머 사이의 분자량 차이가 설정값 이상일 경우 코어-쉘 구조를 갖는다. 예를 들어, 팽윤성 폴리머로서 분자량이 1만 이하인 폴리비닐리덴플루오라이드(PVdF)와 비팽윤성 폴리머로서 분자량이 25만인 폴리아크릴로니트릴(PAN)을 혼합하여 방사하면, 방사된 나노섬유(150)는 분자량이 큰 비팽윤성 폴리머가 나노섬유(150)의 코어 부분에 위치하고 분자량이 작은 팽윤성 폴리머가 쉘 부분에 위치하는 형태를 가지고 있다. 그 결과, 본 발명의 다공성 나노섬유 웹(15)은 비팽윤성 폴리머 코어(150b)의 외부에 팽윤성 폴리머 쉘(150a)이 둘러싸는 코어-쉘 구조의 나노섬유(150)로 구성된다.When the porous nanofiber web 15 mixes the swellable polymer and the non-swellable polymer to spun the mixed polymer, the spun nanofiber 150 has a core-shell structure when the molecular weight difference between the two polymers to be mixed is greater than or equal to a set value. Have For example, when the polyvinylidene fluoride (PVdF) having a molecular weight of 10,000 or less as a swellable polymer and the polyacrylonitrile (PAN) having a molecular weight of 250,000 as a non-swellable polymer are mixed and spun, the spun nanofibers 150 The non-swellable polymer having a large molecular weight is located in the core portion of the nanofibers 150 and the swellable polymer having a small molecular weight is positioned in the shell portion. As a result, the porous nanofiber web 15 of the present invention is composed of a core-shell structured nanofiber 150 surrounded by the swellable polymer shell 150a on the outside of the non-swellable polymer core 150b.
나노섬유(150)가 코어-쉘 구조를 가지는 것은 저온일 때 다공성 나노섬유 웹(15)은 소수성 재료이고 외측에 배치된 폴리비닐리덴플루오라이드(PVdF)에 의해 소수성 성질을 나타내나, 팽윤성 폴리머의 융점 이상으로 온도가 올라가면 친수성 재료인 폴리아크릴로니트릴(PAN)에 의해 친수성으로 변하는 것으로부터 확인할 수 있다.The nanofiber 150 has a core-shell structure when the low temperature porous nanofiber web 15 is a hydrophobic material and exhibits hydrophobic properties by polyvinylidene fluoride (PVdF) disposed on the outside. When temperature rises above melting | fusing point, it can confirm from changing into hydrophilicity by polyacrylonitrile (PAN) which is a hydrophilic material.
따라서, 본 발명에서는 팽윤성 폴리머와 비팽윤성 폴리머를 조합하여 혼합 폴리머를 구성할 때 분자량의 차이가 20배 이상인 것이 바람직하며, 용매에 용해된 후 방사방법으로 나노섬유로 제조될 수 있는 폴리머일 것이 요구된다.Therefore, in the present invention, when the swellable polymer and the non-swellable polymer are combined to form a mixed polymer, the difference in molecular weight is preferably 20 times or more, and it is required to be a polymer that can be made of nanofibers by spinning after dissolving in a solvent. do.
또한, 비팽윤성 폴리머는 팽윤성 폴리머와 비교할 때 분자량이 크기 때문에 융점도 상대적으로 높은 것으로 나타났다. 이 경우, 비팽윤성 폴리머는 융점이 180℃ 이상인 수지인 것이 바람직하고, 팽윤성 폴리머는 융점이 150℃이하, 바람직하게는 100~150℃ 범위 내의 융점을 가지는 수지인 것이 바람직하다.In addition, the non-swellable polymer was found to have a relatively high melting point because of its high molecular weight compared to the swellable polymer. In this case, the non-swellable polymer is preferably a resin having a melting point of 180 ° C. or higher, and the swellable polymer is preferably a resin having a melting point of 150 ° C. or lower, preferably in the range of 100 to 150 ° C.
더욱이, 비팽윤성 폴리머는 팽윤성 폴리머와 비교할 때 분자량의 차이로 인하여 유기 전해액에 포함된 용매에 상대적으로 팽윤이 더디게 이루어지거나 팽윤이 이루어지지 않는 폴리머가 사용된다.Furthermore, non-swellable polymers are polymers which are relatively slow or do not swell with a solvent contained in the organic electrolyte due to the difference in molecular weight when compared with the swellable polymer.
본 발명에서 팽윤성 폴리머는 전지의 충전 및 방전시에 음극 및 양극에서 산화 또는 환원되는 리튬 이온을 운반해주는 통로 역할을 해줄 수 있도록 전도성이 우수한 고분자로 이루어지는 것이 요구된다.In the present invention, the swellable polymer is required to be made of a polymer having excellent conductivity so as to serve as a path for transporting lithium ions that are oxidized or reduced at the cathode and the anode during charging and discharging of the battery.
본 발명에 사용 가능한 팽윤성 폴리머는 전해액에 팽윤이 일어나는 수지로서 전기 방사법에 의하여 초극세 섬유로 형성 가능한 것으로, 예를 들어, 폴리비닐리덴플루오라이드(PVDF), 폴리(비닐리덴플루오라이드-코-헥사플루오로프로필렌), 퍼풀루오로폴리머, 폴리비닐클로라이드 또는 폴리비닐리덴 클로라이드 및 이들의 공중합체 및 폴리에틸렌글리콜 디알킬에테르 및 폴리에틸렌글리콜 디알킬에스터를 포함하는 폴리에틸렌글리콜 유도체, 폴리(옥시메틸렌-올리 고-옥시에틸렌), 폴리에틸렌옥사이드 및 폴리프로필렌옥사이드를 포함하는 폴리옥사이드, 폴리비닐아세테이트, 폴리(비닐피롤리돈-비닐아세테이트), 폴리스티렌 및 폴리스티렌 아크릴로니트릴 공중합체, 폴리아크릴로니트릴 메틸메타크릴레이트 공중합체를 포함하는 폴리아크릴로니트릴 공중합체, 폴리메틸메타크릴레이트, 폴리메틸메타크릴레이트 공중합체 및 이들의 혼합물을 들 수 있다.The swellable polymers usable in the present invention are resins that swell in the electrolyte and can be formed into ultrafine fibers by electrospinning. For example, polyvinylidene fluoride (PVDF), poly (vinylidene fluoride-co-hexafluoro) Ropropylene), perfuluropolymer, polyvinylchloride or polyvinylidene chloride and copolymers thereof and polyethylene glycol derivatives including polyethylene glycol dialkyl ether and polyethylene glycol dialkyl ester, poly (oxymethylene-oligo-oxy Ethylene), polyoxides including polyethylene oxide and polypropylene oxide, polyvinylacetate, poly (vinylpyrrolidone-vinylacetate), polystyrene and polystyrene acrylonitrile copolymers, polyacrylonitrile methyl methacrylate copolymers Polyacrylonitrile containing Copolymers, polymethyl methacrylates, polymethyl methacrylate copolymers, and mixtures thereof.
또한, 본 발명에서 사용 가능한 비팽윤성 폴리머는 전기방사를 위해 유기용매에 용해될 수 있고 유기 전해액에 포함되는 유기 용매에 의해 팽윤성 폴리머보다 팽윤이 더디게 일어나거나 팽윤이 일어나지 않으며, 융점이 180℃ 이상인 수지로서, 예를 들어, 폴리아크릴로니트릴(PAN), 폴리아마이드, 폴리이미드, 폴리아마이드이미드, 폴리(메타-페닐렌 이소프탈아미이드), 폴리설폰, 폴리에테르케톤, 폴리에틸렌텔레프탈레이트, 폴리트리메틸렌텔레프탈레이트, 폴리에틸렌 나프탈레이트 등과 같은 방향족 폴리에스터, 폴리테트라플루오로에틸렌, 폴리디페녹시포스파젠, 폴리{비스[2-(2-메톡시에톡시)포스파젠]} 같은 폴리포스파젠류, 폴리우레탄 및 폴리에테르우레탄을 포함하는 폴리우레탄공중합체, 셀룰로오스 아세테이트, 셀룰로오스 아세테이트 부틸레이트, 셀룰로오스 아세테이트 프로피오네이트 등을 사용할 수 있다. In addition, the non-swellable polymers usable in the present invention can be dissolved in an organic solvent for electrospinning, and swelling is slower than swelling polymers or swelling by an organic solvent included in the organic electrolyte, and the resin has a melting point of 180 ° C or higher. As, for example, polyacrylonitrile (PAN), polyamide, polyimide, polyamideimide, poly (meth-phenylene isophthalamide), polysulfone, polyetherketone, polyethylene terephthalate, polytrimethylene Aromatic polyesters such as telephthalate, polyethylene naphthalate and the like, polyphosphazenes such as polytetrafluoroethylene, polydiphenoxyphosphazene, poly {bis [2- (2-methoxyethoxy) phosphazene], poly Polyurethane copolymers including urethanes and polyetherurethanes, cellulose acetates, cellulose acetate butylenes Yite, cellulose acetate propionate, etc. can be used.
본 발명에서는 다공성 나노섬유 웹(15)이 비팽윤성 폴리머 코어(150b)의 외부에 팽윤성 폴리머 쉘(150a)이 둘러싸는 코어-쉘 구조의 나노섬유(150)로 형성되도록 다공성 나노섬유 웹(15)의 제조에 사용되는 방사용액은 팽윤성 폴리머와 비팽윤성 폴리머를 혼합하여 혼합 폴리머를 구성할 때 분자량의 차이를 선택하는 것이 필요하다. 따라서, 팽윤성 폴리머와 비팽윤성 폴리머 사이의 분자량 차이는 적어도 20배 이상이 되도록 조합하는 것이 바람직하다.In the present invention, the porous nanofiber web 15 is formed of the core-shell structured nanofibers 150 surrounded by the swellable polymer shell 150a on the outside of the non-swellable polymer core 150b. The spinning solution used in the preparation of the swellable polymer and the non-swellable polymer are mixed to form a mixed polymer, it is necessary to select the difference in molecular weight. Therefore, it is preferable to combine so that the difference in molecular weight between the swellable polymer and the non-swellable polymer is at least 20 times or more.
한편, 다공성 나노섬유 웹(15)은 팽윤성 폴리머와 비팽윤성 폴리머가 용해된 방사용액을 방사하여 얻어지며, 도 3에 도시된 에어 전기방사(AES: Air-electrospinning) 장비를 사용하여 방사하는 것이 바람직하다.On the other hand, the porous nanofiber web 15 is obtained by spinning the spinning solution in which the swellable polymer and the non-swellable polymer are dissolved, it is preferable to spin using the air-electrospinning (AES) equipment shown in FIG. Do.
본 발명에서 사용 가능한 방사방법으로는 에어 전기방사(AES) 이외에 전기방사(electrospinning), 전기분사(electrospray), 전기분사방사(electroblown spinning), 원심전기방사(centrifugal electrospinning), 및 플래쉬 전기방사(flash-electrospinning) 등을 사용할 수 있다. The spinning methods usable in the present invention include, in addition to air electrospinning (AES), electrospinning, electrospray, electroblown spinning, centrifugal electrospinning, and flash electrospinning (flash). electrospinning).
예를 들어, 에어 전기방사(AES)에 의해 제조되는 다공성 나노섬유 웹(15)은 10 내지 25㎛인 것이 바람직하며, 보다 바람직하게는 10 내지 15㎛인 것이 적당하다. 다공성 나노섬유 웹(15)의 두께가 10㎛ 미만인 경우, 팽윤성 폴리머 쉘(150a)에 대한 겔화가 이루어진 후에 잔류하는 비팽윤성 폴리머 코어(150b)의 두께가 너무 얇아지게 되어 쇼트가 발생될 수 있으며, 두께가 25㎛를 초과하는 경우, 겔화되는 팽윤성 폴리머 쉘(150a)의 두께도 증가하여 이온 전도도가 떨어지게 된다.For example, the porous nanofiber web 15 produced by air electrospinning (AES) is preferably 10 to 25 mu m, more preferably 10 to 15 mu m. When the thickness of the porous nanofiber web 15 is less than 10 μm, a short may occur because the thickness of the non-swellable polymer core 150b remaining after gelation of the swellable polymer shell 150a is made too thin. When the thickness exceeds 25 μm, the thickness of the gelled swellable polymer shell 150a also increases, resulting in poor ionic conductivity.
상기 폴리머 전해질(5)의 다공성 나노섬유 웹(15)에 함입되는 유기 전해액은 비수성 유기용매와 리튬염의 용질을 포함한다. The organic electrolyte embedded in the porous nanofiber web 15 of the polymer electrolyte 5 includes a non-aqueous organic solvent and a solute of lithium salt.
상기 유기용매는, 팽윤성 폴리머에 대한 용해성이 우수한 한편 비팽윤성 폴리머에 대한 용해성이 낮으며, 또한 나노섬유(150)가 코어-쉘 구조를 가지고 파이버의 외측에 팽윤성 폴리머 쉘(150a)이 배치되어 있기 때문에, 다공성 나노섬유 웹(15)에 함입되는 유기 전해액의 유기용매는 주로 팽윤성 폴리머를 겔화하여, 가소화시키는 작용이 이루어진다.The organic solvent has excellent solubility in the swellable polymer, low solubility in the non-swellable polymer, and the nanofiber 150 has a core-shell structure, and the swellable polymer shell 150a is disposed outside the fiber. Therefore, the organic solvent of the organic electrolyte solution embedded in the porous nanofiber web 15 mainly gelates the swellable polymer and plasticizes it.
상기 비수성 유기용매로는 카보네이트, 에스테르, 에테르 또는 케톤을 사용할 수 있다. 상기 카보네이트로는 디메틸 카보네이트(DMC), 디에틸 카보네이트(DEC), 디프로필 카보네이트(DPC), 메틸프로필 카보네이트(MPC), 에틸프로필 카보네이트(EPC), 메틸에틸 카보네이트(MEC), 에틸렌 카보네이트(EC), 프로필렌 카보네이트(PC), 부틸렌 카보네이트(BC) 등이 사용될 수 있으며, 상기 에스테르로는 부티로락톤(BL), 데카놀라이드(decanolide), 발레로락톤(valerolactone), 메발로노락톤(mevalonolactone), 카프로락톤(caprolactone), n-메틸 아세테이트, n-에틸 아세테이트, n-프로필 아세테이트 등이 사용될 수 있으며, 상기 에테르로는 디부틸 에테르 등이 사용될 수 있으며, 상기 케톤으로는 폴리메틸비닐케톤이 있으나, 본 발명은 비수성 유기용매의 종류에 한정되는 것은 아니며, 또한 1종 이상을 혼합하여 사용할 수 있다.As the non-aqueous organic solvent, carbonate, ester, ether or ketone may be used. The carbonate may be dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylpropyl carbonate (EPC), methylethyl carbonate (MEC), ethylene carbonate (EC) , Propylene carbonate (PC), butylene carbonate (BC) and the like can be used, the ester is butyrolactone (BL), decanolide (decanolide), valerolactone (valerolactone), mevalonolactone (mevalonolactone ), Caprolactone (caprolactone), n-methyl acetate, n-ethyl acetate, n-propyl acetate and the like can be used, the ether may be dibutyl ether and the like, the ketone is polymethyl vinyl ketone However, the present invention is not limited to the type of non-aqueous organic solvent, and may be used by mixing one or more kinds.
또한, 상기 리튬염은 전지 내에서 리튬 이온의 공급원으로 작용하여 기본적인 리튬 전지의 작동을 가능하게 하며, 그 예로는 LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiCF3SO3, LiN(CF3SO2)2, LiN(C2F5SO2)2, LiAlO4, LiSbF6, LiCl, LiI, LiAlCl4, LiN(CxF2x+1SO2)(CyF2x+1SO2)(여기서, x 및 y는 자연수임) 및 LiSO3CF3로 이루어진 군에서 선택되는 것을 하나 이상 또는 이들의 혼합물을 포함한다.In addition, the lithium salt acts as a source of lithium ions in the battery to enable operation of the basic lithium battery, for example, LiPF 6 , LiBF 4 , LiSbF 6 , LiAsF 6 , LiClO 4 , LiCF 3 SO 3 , LiN (CF 3 SO 2 ) 2 , LiN (C 2 F 5 SO 2 ) 2 , LiAlO 4 , LiSbF 6 , LiCl, LiI, LiAlCl 4 , LiN (C x F 2x + 1 SO 2 ) (C y F 2x + 1 SO 2 ), wherein x and y are natural water and LiSO 3 CF 3 includes one or more or mixtures thereof.
상기 무기물 입자는 Al2O3, TiO2, BaTiO3, Li2O, LiF, LiOH, Li3N, BaO, Na2O, Li2CO3, CaCO3, LiAlO2, SiO2, SiO, SnO, SnO2, PbO2, ZnO, P2O5, CuO, MoO, V2O5, B2O3, Si3N4, CeO2, Mn3O4, Sn2P2O7, Sn2B2O5, Sn2BPO6 및 이들의 각 혼합물 중에서 선택된 적어도 1종을 사용할 수 있다. The inorganic particles are Al 2 O 3 , TiO 2 , BaTiO 3 , Li 2 O, LiF, LiOH, Li 3 N, BaO, Na 2 O, Li 2 CO 3 , CaCO 3 , LiAlO 2 , SiO 2 , SiO, SnO , SnO 2 , PbO 2 , ZnO, P 2 O 5 , CuO, MoO, V 2 O 5 , B 2 O 3 , Si 3 N 4 , CeO 2 , Mn 3 O 4 , Sn 2 P 2 O 7 , Sn 2 B 2 O 5, Sn 2 BPO 6 and can be used at least one member selected from among those of the respective mixtures.
상기 혼합물이 팽윤성 폴리머와 비팽윤성 폴리머, 및 무기물 입자로 이루어지는 경우, 첨가되는 무기물 입자의 함량은 무기물 입자의 크기가 10 내지 100nm 사이일 때 혼합물 전체에 대하여 10 내지 25 중량% 범위로 함유하는 것이 바람직하다. 더욱 바람직하게는 무기물 입자를 10 내지 20 중량% 범위로 함유하며 크기가 15 내지 25nm 범위인 것이 좋다.When the mixture consists of a swellable polymer, a non-swellable polymer, and inorganic particles, the content of the added inorganic particles is preferably contained in the range of 10 to 25% by weight based on the total mixture when the size of the inorganic particles is between 10 and 100 nm. Do. More preferably, the inorganic particles are contained in the range of 10 to 20% by weight, and the size is in the range of 15 to 25 nm.
무기물 입자의 함량이 혼합물 전체에 대하여 10 중량% 미만인 경우 필름 형태를 유지하지 못하고 수축이 발생하고 원하는 내열 특성이 얻어지지 못하며, 25 중량%를 초과하는 경우 방사노즐 팁(tip)이 오염되는 방사 트러블 현상이 발생하며 용매 휘발이 빨라서 필름 강도가 떨어지게 된다.If the content of the inorganic particles is less than 10% by weight based on the entire mixture, the film does not maintain the film form, shrinkage occurs, the desired heat resistance characteristics are not obtained, and if it exceeds 25% by weight, the radiation troubles that contaminate the spinning nozzle tip Phenomenon occurs and the solvent volatilization is fast and the film strength decreases.
또한, 무기물 입자의 크기가 10nm 미만이면 부피가 너무 커져 다루기 어렵고, 100nm를 초과하는 경우 무기물 입자가 뭉치는 현상이 발생하여 섬유 밖으로 노출되는 것이 많이 생겨 섬유의 강도가 떨어지는 원인이 된다. In addition, when the size of the inorganic particles is less than 10nm, the volume is too large and difficult to handle, and when it exceeds 100nm, the phenomenon that the inorganic particles are agglomerated occurs a lot of exposed outside the fiber causes the strength of the fiber is lowered.
한편, 본 발명은 도 2에 도시된 제2실시예와 같이, 제1실시예의 무기공 타입의 겔형 폴리머 전해질(5)의 일측 또는 양측에 적층되어 접착층으로 이용되는 초박막의 무기공 폴리머 필름층(5a)을 포함할 수 있다.On the other hand, the present invention, as shown in the second embodiment shown in Figure 2, the inorganic porous polymer film layer of the ultra-thin film laminated on one side or both sides of the gel polymer electrolyte of the inorganic type of the first embodiment (2) used as an adhesive layer ( 5a).
상기 제2실시예의 구조는 예를 들어, 방사노즐이 콜렉터의 진행방향을 따라 간격을 두고 배치된 멀티-홀(multi-hole) 방사팩을 사용하여 에어 전기방사(AES)에 의해 먼저 혼합 폴리머가 용해된 제1방사용액을 사용하여 제1 다공성 나노섬유 웹(15)을 형성한 후, 이어서 단일 폴리머가 용해된 제2방사용액을 사용하여 박막의 제2 나노섬유 웹을 제1 다공성 나노섬유 웹(15)의 상부에 적층하여 2층 구조의 제1 및 제2 다공성 나노섬유 웹을 형성한다. In the structure of the second embodiment, the polymer is first mixed by air electrospinning (AES) using, for example, a multi-hole spinning pack in which the spinning nozzles are spaced along the direction of the collector. After forming the first porous nanofiber web 15 using the dissolved first spinning solution, the second nanofiber web of the thin film was first formed by using the second spinning solution in which a single polymer was dissolved. Stacked on top of 15 to form first and second porous nanofiber webs of two-layer structure.
상기 제2방사용액을 준비하는 데 사용되는 폴리머는 전해액에 팽윤이 이루어지며 리튬 이온의 전도가 가능하며 접착성이 우수한 고분자 수지로서, PVDF(폴리비닐리덴플루오라이드), PEO(Poly-Ethylen Oxide), PMMA(폴리메틸메타크릴레이트), TPU(Thermoplastic Poly Urethane) 중 어느 하나를 사용할 수 있으며, PVDF와 같은 팽윤성이면서 이온 전도가 우수하고 접착성도 우수한 고분자가 바람직하다.The polymer used to prepare the second spinning solution is a polymer resin that swells in the electrolyte and is capable of conducting lithium ions and has excellent adhesion, and includes PVDF (polyvinylidene fluoride) and PEO (Poly-Ethylen Oxide) One of PMMA (polymethyl methacrylate) and TPU (Thermoplastic Poly Urethane) may be used, and a polymer having excellent swelling and excellent ion conductivity and adhesiveness, such as PVDF, is preferable.
그 후, 후속공정에서 2층 구조의 제1 및 제2 다공성 나노섬유 웹을 제2 다공성 나노섬유 웹의 융점보다 다소 낮은 온도로 설정된 예를 들어, 적외선 램프 히터를 제2 다공성 나노섬유 웹이 대향하여 통과하도록 열처리하면 제2 다공성 나노섬유 웹은 무기공 필름(5a)으로 변환되어 제1 다공성 나노섬유 웹(15)과 무기공 필름(5a)의 적층 구조가 얻어진다.Subsequently, in a subsequent process, for example, an infrared lamp heater is used as the second porous nanofiber web to set the first and second porous nanofiber webs having a two-layer structure at a temperature slightly lower than the melting point of the second porous nanofiber web. When the heat treatment is directed toward, the second porous nanofiber web is converted into the inorganic porous film 5a to obtain a laminated structure of the first porous nanofiber web 15 and the inorganic porous film 5a.
상기 무기공 필름(5a)은 2 내지 5㎛ 두께로 형성하는 것이 바람직하며, 2㎛ 미만인 경우, 접착층으로서의 기능이 약하고, 5㎛를 초과하는 경우 전체적인 폴리머 전해질의 두께가 박막화가 어렵고 동시에 이온 전도도가 낮아지게 된다. Preferably, the inorganic porous film 5a is formed to have a thickness of 2 to 5 µm, and when the thickness is less than 2 µm, the function of the adhesive layer is weak. Will be lowered.
이하에 도 3 내지 도 6을 참고하여, 본 발명에 따른 리튬 이온 폴리머 전지의 제조방법을 설명한다.Hereinafter, a method of manufacturing a lithium ion polymer battery according to the present invention will be described with reference to FIGS. 3 to 6.
도 3은 본 발명에 따른 폴리머 전해질로 이용되는 다공성 분리막의 제조공정을 나타내는 공정 단면도, 도 4는 본 발명에 따른 양극과 폴리머 전해질로 사용되는 다공성 분리막의 봉지공정을 나타내는 공정 단면도, 도 5는 본 발명에 따라 조립된 전극 조립체의 개략 단면도, 도 6은 본 발명에 따라 조립된 전극 조립체의 개략 평면도이다.3 is a cross-sectional view showing a manufacturing process of a porous separator used as a polymer electrolyte according to the present invention, FIG. 4 is a cross-sectional view showing a sealing process of a porous separator used as a positive electrode and a polymer electrolyte according to the present invention, and FIG. Schematic cross-sectional view of an electrode assembly assembled in accordance with the invention, FIG. 6 is a schematic plan view of an electrode assembly assembled in accordance with the present invention.
본 발명에서는 먼저 도 3과 같이 다공성 나노섬유 웹(15)을 예를 들어, 에어 전기방사(AES)에 의해 제조한다.In the present invention, first, as shown in FIG. 3, the porous nanofiber web 15 is manufactured by, for example, air electrospinning (AES).
즉, 도 3에 나타낸 에어분사 전기방사장치를 사용하여 충분한 점도를 지닌 혼합 방사용액이 방사되는 방사 노즐(24)과 콜렉터(26) 사이에 90~120Kv의 고전압 정전기력을 인가함에 의해 콜렉터(26)에 초극세 나노섬유(150)가 방사되어 다공성 나노섬유 웹(15)을 형성하며, 이 경우 각 방사 노즐(24)마다 에어(24a)를 분사함에 의해 방사된 나노섬유(150)가 콜렉터(26)에 포집되지 못하고 날리는 것을 잡아주게 된다. That is, the collector 26 is applied by applying a high voltage electrostatic force of 90 to 120 Kv between the spinning nozzle 24 and the collector 26 to which the mixed spinning solution having a sufficient viscosity is radiated using the air spray electrospinning device shown in FIG. The ultrafine nanofibers 150 are radiated to form a porous nanofiber web 15, in which case the radiated nanofibers 150 are sprayed by injecting air 24a at each spinning nozzle 24 to the collector 26. It can't be captured and catches flying.
본 발명에서 혼합방사용액은 40~90중량% 비팽윤성 고분자 물질과 10~60중량%의 팽윤성 고분자 물질을 2성분계 용매 또는 1성분계 용매에 첨가하여 제조한다. 이 경우, 혼합방사용액에 사용되는 용매는 비등점(BP: boiling point)이 높은 것과 낮은 것을 혼합한 2성분계 용매를 사용하는 것이 바람직하다. In the present invention, the mixed spinning solution is prepared by adding 40-90 wt% non-swellable polymer material and 10-60 wt% of swellable polymer material to a two-component solvent or a one-component solvent. In this case, the solvent used for the mixed spinning solution is preferably a two-component solvent in which a boiling point (BP) is mixed with a high boiling point.
본 발명에서 사용하는 에어분사 전기방사장치는 비팽윤성 폴리머 물질과 팽윤성 폴리머 물질이 용매와 혼합되어 방사가 이루어질 때까지 상분리를 방지하도록 공압을 이용한 믹싱 모터(22a)를 구동원으로 사용하는 교반기(22)를 내장한 믹싱 탱크(Mixing Tank)(21)와, 고전압 발생기가 연결된 다수의 방사노즐(24)이 매트릭스 형태로 배치된 멀티-홀 노즐팩(도시되지 않음)을 포함한다. 믹싱 탱크(21)로부터 도시되지 않은 정량 펌프와 이송관(23)을 통하여 연결된 다수의 방사노즐(24)로 토출되는 혼합방사용액은 고전압 발생기에 의하여 하전된 방사노즐(24)을 통과하면서 나노 섬유(150)로 방출되고, 일정 속도로 이동하는 컨베이어 형태의 접지된 콜렉터(26) 위에 나노 섬유(150)가 축적되어 다공성 나노섬유 웹(15)을 형성한다. The air spray electrospinning apparatus used in the present invention is a stirrer 22 using a mixing motor 22a using pneumatic pressure as a driving source to prevent phase separation until a non-swellable polymer material and a swellable polymer material are mixed with a solvent and spinning. It includes a mixing tank (Mixing Tank) 21, and a multi-hole nozzle pack (not shown) in which a plurality of spinning nozzles 24 to which a high voltage generator is connected are arranged in a matrix form. The mixed spinning solution discharged from the mixing tank 21 to a plurality of spinning nozzles 24 connected through a metering pump and a transfer pipe 23, not shown, passes through the spinning nozzles 24 charged by the high voltage generator, and the nanofibers. The nanofibers 150 are accumulated on a grounded collector 26 in the form of a conveyor which is discharged to 150 and moves at a constant speed to form a porous nanofiber web 15.
이 경우, 본 발명에서는 후속공정 및 후술하는 양극 봉지 공정의 작업성을 개선할 수 있도록 인장강도가 높은 트랜스퍼 시트(25a)를 트랜스퍼 롤(25)로부터 에어분사 전기방사장치의 콜렉터(26)의 상부로 연속적으로 투입함에 의해 트랜스퍼 시트(25a)의 상부에 다공성 나노섬유 웹(15)을 적층 형성한다.In this case, in the present invention, the transfer sheet 25a having a high tensile strength is transferred from the transfer roll 25 to the upper part of the collector 26 of the air spray electrospinning apparatus so as to improve the workability of the subsequent process and the positive electrode encapsulation process described later. The continuous nano fiber web 15 is formed by laminating the upper portion of the transfer sheet 25a.
상기 트랜스퍼 시트(25a)는 예를 들어, 종이, 또는 혼합방사용액의 방사시에 이에 포함된 용매에 의해 용해가 이루어지지 않는 고분자 재료로 이루어진 부직포, PE, PP 등의 폴리올레핀계 필름을 사용할 수 있다. 다공성 나노섬유 웹(15) 자체만으로 이루어진 경우 인장강도가 낮아서 높은 이송속도를 가지고 이송되면서 건조 공정, 캘린더링 공정 및 권선 공정이 이루어지는 것이 어렵다.The transfer sheet 25a may be, for example, a polyolefin-based film such as nonwoven fabric, PE, PP, or the like, which is made of paper or a polymer material that is not dissolved by a solvent contained therein when spinning a mixed spinning solution. . In the case of the porous nanofiber web 15 itself, the tensile strength is low, so that the drying process, the calendering process, and the winding process are difficult to be carried out at a high feed rate.
더욱이, 다공성 나노섬유 웹(15)을 제조한 후 후속된 양극 또는 음극과의 봉지 공정을 높은 이송속도를 가지고 연속적으로 실행되기 어려우나 상기한 트랜스퍼 시트(25a)를 이용하는 경우 충분한 인장강도를 제공함에 따라 공정처리 속도를 크게 높일 수 있다. Moreover, after the porous nanofiber web 15 is produced, the subsequent encapsulation process with the positive or negative electrode is difficult to be carried out continuously with a high feed rate, but when the transfer sheet 25a described above is used, sufficient tensile strength is provided. The processing speed can be greatly increased.
또한, 다공성 나노섬유 웹(15)만을 사용하는 경우 정전기로 인하여 타 물체에 들러붙는 현상이 발생하여 작업성이 떨어지게 되나 트랜스퍼 시트(25a)를 이용하는 경우 이러한 문제를 해결할 수 있다. In addition, when only the porous nanofiber web 15 is used, the phenomenon of sticking to other objects occurs due to static electricity, resulting in poor workability, but when the transfer sheet 25a is used, this problem can be solved.
상기 트랜스퍼 시트(25a)는 도 4와 같이 전극과의 롤 프레싱을 거친 후, 박리되어 제거된다.The transfer sheet 25a is subjected to roll pressing with an electrode as shown in FIG. 4, and then peeled off and removed.
상기와 같이 혼합방사용액을 준비한 후 멀티-홀 노즐팩을 사용하여 에어 전기방사(AES: Air-electrospinning) 방법으로 방사를 진행하면 0.3~1.5um 직경의 초극세 섬유의 방사가 이루어지며, 섬유의 생성과 동시에 3차원의 네트워크 구조로 융착되어 적층된 형태의 다공성 나노섬유 웹(15)이 트랜스퍼 시트(25a)의 상부에 형성된다. 초극세 섬유로 이루어진 나노섬유 웹(15)은 초박막, 초경량으로서, 부피 대비 표면적 비가 높고, 높은 기공도를 가진다.After preparing the mixed spinning solution as described above, spinning is performed by air electrospinning (AES) using a multi-hole nozzle pack, and spinning of ultra-fine fibers having a diameter of 0.3 to 1.5 μm is achieved. At the same time, a porous nanofiber web 15 of a fused and stacked form in a three-dimensional network structure is formed on the transfer sheet 25a. Nanofiber web 15 made of ultra-fine fibers is an ultra-thin film, ultra-light weight, has a high surface area to volume ratio and high porosity.
상기와 같이 얻어진 다공성 나노섬유 웹(15)은 그 후 프리히터(28)에 의한 선 건조구간(Pre-air Dry Zone)을 통과하면서 다공성 나노섬유 웹(15)의 표면에 잔존해 있는 용매와 수분의 양을 조절하는 공정을 거친 후 가열 압착롤러(29)를 이용한 캘린더링 공정이 이루어진다. The porous nanofiber web 15 obtained as described above is then passed through a pre-air dry zone by the preheater 28 and the solvent and water remaining on the surface of the porous nanofiber web 15. After going through the process of adjusting the amount of calendering process using a heat compression roller 29 is made.
프리히터(28)에 의한 선 건조구간(Pre-Air Dry Zone)은 20~40℃의 에어를 팬(fan)을 이용하여 웹에 인가하여 다공성 나노섬유 웹(15)의 표면에 잔존해 있는 용매와 수분의 양을 조절함에 의해 다공성 나노섬유 웹(15)이 벌키(bulky)해지는 것을 조절하여 막의 강도를 증가시켜주는 역할과 동시에 다공성(Porosity)을 조절할 수 있게 된다. Pre-Air Dry Zone by the preheater 28 is a solvent remaining on the surface of the porous nanofiber web 15 by applying air of 20 ~ 40 ℃ to the web using a fan (fan) By controlling the amount of moisture and the porous nanofiber web 15 is to control the bulky (bulky) to increase the strength of the membrane and at the same time it is possible to control the porosity (Porosity).
이 경우, 용매의 휘발이 지나치게 된 상태에서 캘린더링이 이루어지면 다공성은 증가하나 웹의 강도가 약해지고, 반대로 용매의 휘발이 적게 되면 웹이 녹는 현상이 발생하게 된다.In this case, if calendering is performed in a state in which the volatilization of the solvent is excessive, the porosity increases but the strength of the web decreases. On the contrary, when the volatilization of the solvent decreases, the web melts.
상기한 선 건조 공정에 후속된 다공성 나노섬유 웹(15)의 캘린더링(calendering) 공정에서는 가열 압착롤러(29)를 사용하여 진행되며, 이 경우 캘린더링 온도가 너무 낮으면 웹(web)이 너무 벌키(Bulky)해져서 강성을 갖지 못하고 너무 높으면 웹이 녹아 기공(Pore)이 막히게 된다. 또한, 웹에 잔존해 있는 용매를 완전히 휘발할 수 있는 온도에서 열압착이 이루어져야 하며, 너무 적게 휘발시키게 되면 웹이 녹는 현상이 발생하게 된다.In the calendering process of the porous nanofiber web 15 subsequent to the above-described drying process, the heat compression roller 29 is used, and in this case, if the calendering temperature is too low, the web is too large. If it is bulky and has no rigidity and is too high, the web melts and the pores are blocked. In addition, thermocompression should be performed at a temperature that can completely volatilize the solvent remaining on the web, and if the volatilization is performed too little, the web will melt.
본 발명에서는 가열 압착롤러(29)를 170~210℃의 온도, 0~40kgf/cm2의 압력(압착롤러의 자중압력 제외)으로 설정하여 다공성 나노섬유 웹(15)의 캘린더링을 진행하여, 1차 선 수축을 실시함으로써 실제 사용시에 다공성 분리막의 안정화를 유지할 수 있게 하였다. In the present invention, the heat compression roller 29 is set to a temperature of 170 to 210 ° C. and a pressure of 0 to 40 kgf / cm 2 (excluding the self-weight pressure of the compression roller) to proceed with calendering of the porous nanofiber web 15. By performing the first line shrinkage, the porous membrane can be stabilized in actual use.
비팽윤성 고분자 물질과 팽윤성 고분자 물질이 예를 들어, 각각 PAN과 PVdF 조합인 경우 캘린더링 온도와 압력은 하기와 같다: If the non-swellable polymer material and the swellable polymer material are, for example, a combination of PAN and PVdF, respectively, the calendering temperature and pressure are as follows:
PAN과 PVdF 조합: 170~210℃, 20~30kgf/cm2 PAN and PVdF combination: 170 ~ 210 ℃, 20 ~ 30kgf / cm 2
상기한 웹의 캘린더링 공정이 이루어지면 두께 10~25㎛의 다공성 나노섬유 웹(15), 즉 다공성 분리막이 얻어지게 된다.When the calendaring process of the web is made, a porous nanofiber web 15 having a thickness of 10 to 25 μm, that is, a porous separator is obtained.
또한, 본 발명에서는 필요에 따라 상기한 캘린더링 공정이 이루어진 후 얻어진 다공성 분리막은 바람직하게는 온도 100℃, 풍속 20m/sec인 2차 열풍 건조기(30)를 사용하여 잔류 용매나 수분을 제거하는 공정을 거친 후, 트랜스퍼 시트(25a)가 내측에 배치되는 상태로 다공성 분리막의 권취롤로서 와인더(31)에 권선된다. In addition, in the present invention, the porous membrane obtained after the above calendering process, if necessary, is a step of removing residual solvent or water using a secondary hot air dryer 30 having a temperature of 100 ° C. and a wind speed of 20 m / sec. After passing through, the transfer sheet 25a is wound around the winder 31 as a winding roll of the porous separator in a state in which the transfer sheet 25a is disposed inside.
얻어진 다공성 분리막, 즉 나노섬유 웹(15)은 팽윤성 폴리머와 비팽윤성 폴리머를 혼합하여 혼합 폴리머를 방사할 때 폴리비닐리덴플루오라이드(PVdF)와 폴리아크릴로니트릴(PAN)의 조합과 같이 혼합되는 2 폴리머 사이의 분자량 차이가 설정값 이상이 되도록 설정함에 의해 방사된 나노섬유(150)는 코어-쉘 구조를 갖는다.The obtained porous separator, i.e., the nanofiber web 15 is mixed with a combination of polyvinylidene fluoride (PVdF) and polyacrylonitrile (PAN) when the swellable polymer and the non-swellable polymer are mixed to spun the mixed polymer. The nanofibers 150 spun by setting the molecular weight difference between the polymers to be above a set value have a core-shell structure.
즉, 나노섬유(150)에서 분자량이 큰 폴리아크릴로니트릴(PAN)이 코어 부분에 위치하고 분자량이 작은 폴리비닐리덴플루오라이드(PVdF)가 쉘 부분에 위치하는 형태를 가지고 있다. 그 결과, 본 발명의 다공성 분리막을 구성하는 다공성 나노섬유 웹(15)은 비팽윤성 폴리머 코어(150b)의 외부에 팽윤성 폴리머 쉘(150a)이 둘러싸는 코어-쉘 구조의 나노섬유(150)로 구성된다.That is, in the nanofibers 150, polyacrylonitrile (PAN) having a large molecular weight is located at the core portion and polyvinylidene fluoride (PVdF) having a small molecular weight is positioned at the shell portion. As a result, the porous nanofiber web 15 constituting the porous separator of the present invention is composed of a core-shell structured nanofiber 150 surrounded by the swellable polymer shell 150a on the outside of the non-swellable polymer core 150b. do.
이하에 도 4 및 도 7을 참고하여 전극의 봉지화 공정 및 전지의 조립 공정에 대하여 설명한다.Hereinafter, an electrode encapsulation step and a battery assembling step will be described with reference to FIGS. 4 and 7.
도 4를 참고하면, 2장의 다공성 분리막(15)을 사용한 봉지화 공정에 의해 양극(1)과 음극(3) 중 어느 하나를 봉지화할 수 있다. 실시예 설명에서는 양극(1)의 봉지화를 예를 들어 설명한다.Referring to FIG. 4, one of the positive electrode 1 and the negative electrode 3 may be encapsulated by an encapsulation process using two porous separators 15. In the description of the embodiment, the sealing of the positive electrode 1 will be described by way of example.
먼저, 상기 양극(1)은 스트립 형태의 양극 집전체(11a)에 바이셀(또는 풀셀)을 형성하도록 양극 활물질(11b,11c)을 포함하는 슬러리를 양면 캐스팅하고 롤 프레싱하여 다수의 단위 양극셀(1a-1d)이 순차적으로 형성된 양극 스트립(1n)을 형성하고, 이를 권선기를 사용하여 릴에 권선한다(S11). First, the positive electrode 1 double-sides the slurry including the positive electrode active materials 11b and 11c to form a bi-cell (or full cell) in the strip-shaped positive electrode current collector 11a and roll-presses the plurality of unit positive electrode cells. (1a-1d) forms the anode strip (1n) formed sequentially, and winding it to the reel using a winding machine (S11).
또한, 음극(3)은 양극과 동일한 방식으로 바이셀(또는 풀셀) 구조로 형성한 후(S11), 개별적인 단위 음극셀로 분리하여(S14), 도 5와 같이 다수의 단위 음극셀(3a-3c)을 준비한다.In addition, the negative electrode 3 is formed in a bi-cell (or full cell) structure in the same manner as the positive electrode (S11), and separated into individual unit negative electrode cells (S14), and the plurality of unit negative electrode cells 3a- as shown in FIG. Prepare 3c).
상기 양극 스트립(1n)은, 릴에 권선하기 전에 또는 도 4에 도시된 봉지화 공정이 개시되기 전에 블랭킹 장비를 사용하여 블랭킹(blanking)(즉, 타발 성형)을 실시하여 양극 스트립(1n)으로부터 다수의 단위 양극셀(1a-1d)을 양극 단자(11x)를 형성할 부분을 남기고 부분적으로 분리한다(S12).The anode strip 1n is blanked from the anode strip 1n by blanking (ie, punching) using a blanking equipment before winding to the reel or before the encapsulation process shown in FIG. 4 is started. The plurality of unit positive electrode cells 1a-1d are partially separated, leaving portions for forming the positive electrode terminal 11x (S12).
또한, 상기 블랭킹 공정에서는 양극 스트립(1n)의 스탭-바이-스탭 방식 이송에 따라 1단위 공정 길이만큼 이송한 후, 각각의 단위 공정마다 블랭킹을 실시하여 인접한 단위 양극셀(1a-1d) 사이에는 다수의 타공을 형성하고, 단위 양극셀(1a-1d)과 양 측면에 형성된 마스킹 테이프 부착 영역 사이에 공간을 형성함에 의해 각 단위 양극셀(1a-1d)을 직사각형 또는 정사각형 등의 일정한 면적을 갖는 사각형 형상을 가지며 상호 연결되도록 타발한다.In addition, in the blanking process, the unit strip is transported by one unit process length according to the step-by-step method transfer of the anode strip 1n, and then blanking is performed for each unit process, and thus, between adjacent unit anode cells 1a-1d. By forming a plurality of perforations and forming a space between the unit anode cells 1a-1d and the masking tape attaching regions formed on both sides thereof, each unit anode cell 1a-1d has a constant area such as a rectangle or a square. It has a rectangular shape and punches to be interconnected.
그 후, 도 4와 같이 각각 트랜스퍼 시트(15c,15d)에 적층된 한쌍의 다공성 나노섬유 웹(15a,15b)을 양극 스트립(1n)의 상하부에 배치한 상태에서 한쌍의 다공성 나노섬유 웹(15a,15b)과 양극 스트립(1n)을 한쌍의 열간 압착롤(33a,33b)로 이루어진 롤 프레싱 장치(33)를 연속적으로 통과시키면서 열과 압력을 가한 롤 프레싱을 실시한다(S13). Thereafter, as shown in FIG. 4, the pair of porous nanofiber webs 15a are disposed on the upper and lower portions of the positive electrode strip 1n and the pair of porous nanofiber webs 15a and 15b respectively stacked on the transfer sheets 15c and 15d. 15b) and the positive electrode strip 1n are subjected to roll pressing with heat and pressure while continuously passing the roll pressing apparatus 33 composed of a pair of hot pressing rolls 33a and 33b (S13).
이 경우, 한쌍의 다공성 나노섬유 웹(15a,15b)은 도 6과 같이, 양극 스트립(1n)의 폭보다 소정의 길이만큼 더 넓은 폭을 갖는 스트립 형상을 가지고 있다. 상기 한쌍의 다공성 나노섬유 웹(15a,15b)은 단위 음극셀(3a-3c)의 폭과 동일하게 설정하는 것이 바람직하다. 도 6에서 11x는 양극 단자, 13x는 음극 단자를 가리킨다.In this case, the pair of porous nanofiber webs 15a and 15b have a strip shape having a width wider by a predetermined length than the width of the anode strip 1n, as shown in FIG. Preferably, the pair of porous nanofiber webs 15a and 15b are set equal to the width of the unit cathode cells 3a-3c. In Fig. 6, 11x indicates a positive terminal and 13x indicates a negative terminal.
또한, 상기 단위 양극셀(1a-1d)에 대한 봉지화를 위한 롤 프레싱을 거친 후, 트랜스퍼 시트(15c,15d)는 도 4와 같이 다공성 나노섬유 웹(15a,15b)으로부터 박리되어 제거된다. Further, after the roll pressing for encapsulation of the unit anode cells 1a-1d, the transfer sheets 15c and 15d are peeled off and removed from the porous nanofiber webs 15a and 15b as shown in FIG.
그 결과, 한쌍의 다공성 나노섬유 웹(15a,15b)은 롤-투-롤(Roll-to-Roll) 방법으로 양극 스트립(1n)의 다수의 단위 양극셀(1a-1d)을 순차적으로 봉지화하여 실링이 이루어질 수 있어 높은 생산성을 가진다.As a result, the pair of porous nanofiber webs 15a and 15b sequentially encapsulate a plurality of unit anode cells 1a-1d of the anode strip 1n by a roll-to-roll method. The sealing can be made to have a high productivity.
그 후, 예를 들어, 도 5와 같이 다공성 나노섬유 웹(15)으로 봉지화가 이루어진 다수의 단위 양극 셀(1a-1d) 사이에 각각 단위 음극 셀(3a-3c)을 적층하여 전극 조립체(100)를 형성하고(S15), 전극 조립체(100)의 외부를 둘러싸도록 유기 용매에 팽윤이 되지 않으며 인장강도가 우수한 재료로 이루어진 압박밴드(101)로 테이핑한다(S16). Subsequently, for example, as shown in FIG. 5, the unit cathode cells 3a-3c are stacked between the plurality of unit anode cells 1a-1d encapsulated with the porous nanofiber web 15 to form the electrode assembly 100. ) Is formed (S15), and taped with a pressing band 101 made of a material having excellent tensile strength without swelling in the organic solvent to surround the outside of the electrode assembly 100 (S16).
일반적으로 리튬 이온 폴리머 전지에서 다수의 단위 양극 셀과 단위 음극 셀이 적층된 전극 조립체(100)는 충전 및 방전시에 내부가 팽창되어 셀의 적층방향으로 팽창 및 수축이 발생하는 문제가 존재하며, 이러한 동작이 반복되면 전극 내에 함침되어 있던 액상의 전해액은 전해질로 함침되어 전극과 전해질 사이가 분리되는 현상이 발생하며, 그 결과 점차적으로 계면저항이 증가하여, OCV(개방회로전압)가 감소하는 문제가 있다.In general, an electrode assembly 100 in which a plurality of unit cathode cells and a unit cathode cell are stacked in a lithium ion polymer battery has a problem that expansion and contraction occurs in the stacking direction of cells due to expansion inside thereof during charging and discharging. If this operation is repeated, the liquid electrolyte impregnated in the electrode is impregnated with the electrolyte and separation between the electrode and the electrolyte occurs. As a result, the interface resistance gradually increases, resulting in a decrease in the open circuit voltage (OCV). There is.
본 발명에서는 상기와 같이 전극 조립체(100)의 외부를 비팽윤성 재료로 이루어진 박막 압박밴드(101)로 테이핑함에 따라 충방전 진행시에 전극 조립체(100)의 팽창과 수축이 전극 조립체(100)의 수직방향 대신에 측면방향으로 이루어지도록 유도하여 전해질과 전극 사이의 분리 현상을 방지함에 따라 계면저항의 증가를 억제할 수 있어, OCV(개방회로전압)의 감소를 최소화할 수 있다.In the present invention, as described above, the outside of the electrode assembly 100 is taped with the thin film pressing band 101 made of a non-swellable material, so that the expansion and contraction of the electrode assembly 100 during charging and discharging proceeds. It is possible to reduce the OCV (open circuit voltage) by minimizing the increase in interfacial resistance by inducing the lateral direction instead of the vertical direction to prevent separation between the electrolyte and the electrode.
더욱이, 본 발명에서는 상기 팽윤성 폴리머의 일부가 상기 폴리머 전해질(5)과 연속한 상태로 상기 양극(1) 및 상기 음극(3)에 충전되는 것에 의해 상기 양극(1) 및 음극(3)과 상기 폴리머 전해질(5)과 접착되어, OCV(개방회로전압)의 감소를 최소화할 수 있다.Furthermore, in the present invention, a part of the swellable polymer is filled in the positive electrode 1 and the negative electrode 3 in a continuous state with the polymer electrolyte 5 so that the positive electrode 1 and the negative electrode 3 and the Adhered to the polymer electrolyte 5, the reduction of the OCV (open circuit voltage) can be minimized.
상기 압박밴드(101)는 예를 들어, 셀가드사에서 입수 가능한 PP/PE 또는 PE/PP/PE 부직포나 PET 필름 등의 올레핀계 필름, 박막의 세라믹을 사용할 수 있다.The pressing band 101 may be, for example, an olefin-based film such as PP / PE or PE / PP / PE nonwoven fabric or PET film available from Celgard, and a thin ceramic.
도 5에 도시된 실시예 설명에서는 Z 폴딩 방법으로 다수의 단위 양극 셀(1a-1d) 사이에 단위 음극 셀(3a-3c)을 적층하여 대용량의 전극 조립체(100)를 형성하는 구조를 제시하였으나, 본 발명은 이에 한정되지 않고 다른 방법으로 전극 조립체(100)를 형성하고 압박밴드(101)로 테이핑하는 것도 가능하다.In the exemplary embodiment illustrated in FIG. 5, a structure in which a large capacity electrode assembly 100 is formed by stacking unit cathode cells 3a-3c between a plurality of unit anode cells 1a-1d by a Z folding method is described. In addition, the present invention is not limited thereto. Alternatively, the electrode assembly 100 may be formed and taped to the compression band 101.
이 경우, 필요에 따라 적어도 하나의 강도 보강용 플레이트를 전극 조립체(100)의 일측면 또는 양측면에 조립한 상태로 압박밴드(101) 테이핑이 이루어질 수 있다.In this case, the pressure band 101 may be taped in a state in which at least one strength reinforcing plate is assembled to one side or both sides of the electrode assembly 100.
예를 들어, 단위 양극 셀(1a-1d) 대신에 다수의 단위 음극 셀(3a-3c)을 한쌍의 다공성 나노섬유 웹(15a,15b)을 사용하여 연속적으로 봉지화한 후, 다수의 단위 음극 셀(3a-3c) 사이에 단위 양극 셀(1a-1d)을 적층하여 대용량의 전극 조립체(100)를 형성할 수 있다.For example, instead of unit anode cells 1a-1d, a plurality of unit cathode cells 3a-3c are continuously encapsulated using a pair of porous nanofiber webs 15a, 15b, and then a plurality of unit cathodes are used. The unit anode cells 1a-1d may be stacked between the cells 3a-3c to form a large electrode assembly 100.
또한, 다공성 나노섬유 웹(15a,15b)을 양극(1)과 음극(3) 사이에 넣고, 가열 라미네이션 공정에 의해 일체화시킨 후, 적층하거나 롤식으로 말아서 케이스에 조립할 수 있다.In addition, the porous nanofiber webs 15a and 15b may be sandwiched between the anode 1 and the cathode 3 and integrated by a heating lamination process, and then laminated or rolled to assemble into a case.
더욱이, 다공성 나노섬유 웹(15a,15b)을 각각 양극(1)과 음극(3)의 일면에 접착한 후, 일면에 다공성 나노섬유 웹(15a,15b)이 형성된 양극(1)과 음극(3)을 적층하여, 가열 라미네이션 공정에 의해 일체화시킨 후, 적층하거나 롤식으로 말아서 케이스에 조립할 수 있다.Furthermore, after bonding the porous nanofiber webs 15a and 15b to one surface of the anode 1 and the cathode 3, respectively, the anode 1 and the cathode 3 having the porous nanofiber webs 15a and 15b formed on one surface thereof. ) May be laminated and integrated by a heat lamination process, and then laminated or rolled to assemble into a case.
이어서, 압박밴드(101)로 테이핑된 전극 조립체(100)를 케이스(도시되지 않음)에 내장하고(S17), 유기 전해액을 주입한 후 겔화 공정이 이루어지도록 열처리를 실시하고 밀봉한다(S18,S19). 이 경우, 주입되는 유기 전해액은 다공성 나노섬유 웹(15)에 포함된 팽윤성 폴리머를 300 내지 500% 팽윤시켜서 모두 겔화가 이루어지고 액상의 유기 용매가 실질적으로 잔류하지 않는 적정량을 주입하도록 설정된다. Subsequently, the electrode assembly 100 taped with the pressing band 101 is embedded in a case (not shown) (S17), and after the organic electrolyte is injected, heat treatment is performed to seal the gel (S18, S19). ). In this case, the injected organic electrolytic solution is set to inject an appropriate amount in which all of the swellable polymers contained in the porous nanofiber web 15 are swelled by 300 to 500% to gelate and substantially no liquid organic solvent remains.
본 발명에서는 양극(1)과 음극(3) 사이에 배치된 다공성 나노섬유 웹(15a,15b)이 3차원 기공 구조를 갖는 다공성 막이므로 유기 전해액을 주입할 때 함침이 매우 빠르게 이루어지게 된다.In the present invention, since the porous nanofiber webs 15a and 15b disposed between the anode 1 and the cathode 3 are porous membranes having a three-dimensional pore structure, impregnation is made very quickly when the organic electrolyte is injected.
상기 겔화 공정은 유기 전해액을 주입한 후, 40℃ 내지 120℃ 범위의 온도에서 10분 내지 600분 범위의 조건으로 가열한 후 냉각시킨다.The gelling process is injected after cooling the organic electrolytic solution, and then heated to a condition of 10 minutes to 600 minutes at a temperature range of 40 ℃ to 120 ℃.
따라서, 유기 전해액을 주입한 후, 겔화시키기 위한 열처리 공정에서 열처리 조건을 팽윤성 폴리머의 융점보다 높고 비팽윤성 폴리머의 융점보다 낮은 온도에서 겔화를 진행하면, 나노섬유(150)의 외측에 배치되는 팽윤성 폴리머 쉘(150a)은 가소화가 진행되어 겔화가 이루어지며, 내측에 배치되는 비팽윤성 폴리머 코어(150b)는 미약한 팽윤만 일어나고 체인이 끊어지지 않고 유지됨에 따라 매트릭스 형상을 유지한다. Therefore, after injecting the organic electrolyte, in the heat treatment step for gelling, when the heat treatment conditions are performed at a temperature higher than the melting point of the swellable polymer and lower than the melting point of the non-swellable polymer, the swellable polymer disposed outside the nanofiber 150. The shell 150a undergoes plasticization and gels, and the non-swellable polymer core 150b disposed inside maintains a matrix shape as only a slight swelling occurs and the chain is not broken.
그 결과, 폴리머 전해질(5)은, 겔화가 이루어진 팽윤성 폴리머 쉘(150a)에 의해 전체적으로는 액상의 유기 용매가 실질적으로 잔류하지 않는 무기공 타입의 겔형 전해질을 형성함과 동시에 비팽윤성 폴리머 코어(150b)는 전해액에 팽윤이 이루어지지 않고 형상을 유지한다.As a result, the polymer electrolyte 5 forms an inorganic pore type gel electrolyte in which the liquid organic solvent does not remain substantially as a whole by the swellable polymer shell 150a formed with gelation, and at the same time, the non-swellable polymer core 150b. ) Maintains its shape without swelling in the electrolyte.
그 결과, 겔 상태의 팽윤성 폴리머 쉘(150a)은 전지의 충전 및 방전시에 음극(3) 및 양극(1)에서 산화 또는 환원되는 리튬 이온을 운반해주는 리튬 이온 전도체로서의 기능을 발휘하며, 비팽윤성 폴리머 코어(150b)는 양극(1) 및 음극(3)을 물리적으로 격리하는 세퍼레이터로서 역할을 하여 양극과 음극 사이의 단락을 방지하여 안전성이 향상된다.As a result, the gel-swellable polymer shell 150a functions as a lithium ion conductor that carries lithium ions that are oxidized or reduced at the negative electrode 3 and the positive electrode 1 during charging and discharging of the battery, and is non-swellable. The polymer core 150b serves as a separator that physically isolates the positive electrode 1 and the negative electrode 3, thereby preventing short circuits between the positive electrode and the negative electrode, thereby improving safety.
이 경우, 겔화 공정을 거침에 따라 팽윤된 팽윤성 폴리머의 일부는 양극(1) 및 음극(3)의 내부로 침투가 이루어짐에 따라 전극과 폴리머 전해질(5) 사이의 계면저항이 감소함과 동시에 폴리머 전해질(5)의 박막화를 도모할 수 있다.In this case, a part of the swellable polymer swelled through the gelation process penetrates into the positive electrode 1 and the negative electrode 3, thereby decreasing the interfacial resistance between the electrode and the polymer electrolyte 5 and simultaneously The electrolyte 5 can be thinned.
또한, 코어-쉘 구조를 갖는 본 발명의 나노섬유(150)는 비팽윤성 폴리머 코어(150b)의 외부에 팽윤성 폴리머 쉘(150a)이 둘러싸는 구조를 이루고 있어, 유기 전해액을 함침한 후 겔화 공정을 거치게 될 때 외측에 배치된 팽윤성 폴리머 쉘(150a)이 균일하게 팽윤이 되어, 전해질 막 전체에 대하여 전지 특성이 균일하게 발현될 수 있다.In addition, the nanofiber 150 of the present invention having a core-shell structure has a structure in which the swellable polymer shell 150a is surrounded by the outside of the non-swellable polymer core 150b, so that the gelation process may be performed after impregnating the organic electrolyte solution. When passing through, the swellable polymer shell 150a disposed outside is uniformly swelled, whereby battery characteristics can be uniformly expressed with respect to the entire electrolyte membrane.
상기한 실시예 설명에서는 폴리머 전해질(5)을 형성하기 위하여 코어-쉘 구조를 갖는 나노섬유(15)로 이루어진 단일층의 다공성 나노섬유 웹(15)을 분리막으로 사용한 것을 예시하였으나, 본 발명은 이에 제한되지 않고 다층 구조로 이루어질 수 있다.In the above description of the embodiment has been illustrated that a single layer of porous nanofiber web 15 made of a nanofiber 15 having a core-shell structure to form a polymer electrolyte 5 as a separator, the present invention is It is not limited and may be formed in a multilayer structure.
첨부된 도 8 및 도 9는 본 발명에 따른 복합 다공성 분리막의 일예를 나타내는 단면도이다. 8 and 9 are cross-sectional views showing an example of the composite porous separator according to the present invention.
먼저, 도 8에 도시된 바와 같이, 본 발명에 따른 복합 다공성 분리막(210)은 지지체(matrix)로서 사용되며 미세 기공을 갖는 다공성 부직포(211)와 다공성 부직포(211)의 적어도 일 측면에 접착층으로 사용되며, 전해액을 함침하고 있는 다공성 나노섬유 웹(213)을 구비하고 있다.First, as shown in FIG. 8, the composite porous separator 210 according to the present invention is used as a matrix and has an adhesive layer on at least one side of the porous nonwoven fabric 211 and the porous nonwoven fabric 211 having micropores. And a porous nanofiber web 213 impregnated with an electrolyte solution.
상기 기재로 사용 가능한 다공성 부직포(211)는 코어로서 PP 섬유의 외주에 PE가 코팅된 이중 구조의 PP/PE 섬유로 이루어진 부직포, 또는 폴리에틸렌테레프탈레이트(PET: polyethyleneterephthalate) 섬유로 이루어진 PET 부직포, 셀룰로즈 섬유로 이루어진 부직포 중 어느 하나를 사용할 수 있다.The porous nonwoven fabric 211 which can be used as the substrate is a nonwoven fabric made of a double structured PP / PE fiber coated with PE on the outer circumference of the PP fiber as a core, or a PET nonwoven fabric made of polyethyleneterephthalate (PET) fiber and cellulose fiber. Any one of the nonwovens may be used.
상기 다공성 부직포(211)는 70 내지 80 범위의 기공도를 갖는 것이 바람직하다.The porous nonwoven fabric 211 preferably has a porosity in the range of 70 to 80.
상기 다공성 부직포(211)의 일측면에 적층되는 다공성 나노섬유 웹(13)은 음극과 양극(도시되지 않음) 사이에 삽입되어 조립이 이루어질 때 음극과 접착이 용이하게 이루어지는 접착층 역할을 한다. 이를 위해 다공성 나노섬유 웹(213)은 음극 활물질과의 접착력이 우수한 고분자, 예를 들어 PVDF(폴리비닐리덴 플로라이드)를 전기방사하여 얻어진 것을 사용할 수 있다.The porous nanofiber web 13 stacked on one side of the porous nonwoven fabric 211 is inserted between the cathode and the anode (not shown) to serve as an adhesive layer that is easily bonded to the cathode when assembly is performed. To this end, the porous nanofiber web 213 may be a polymer obtained by electrospinning a polymer having excellent adhesion with a negative electrode active material, for example, PVDF (polyvinylidene fluoride).
또한, 상기 다공성 부직포(211)는 기공이 너무 크기 때문에 도 9에 도시된 실시예의 분리막(210a)과 같이, 기공도를 낮추도록 다공성 나노섬유 웹(213) 대신에 다공성 나노섬유 웹(213)을 무기공 고분자 필름으로 변환하여 초박막의 무기공 필름(213a)을 적용하는 것이 바람직하다.In addition, since the porous nonwoven fabric 211 has too large pores, as shown in the separation membrane 210a of the embodiment shown in FIG. 9, the porous nanofiber web 213 is used instead of the porous nanofiber web 213 to lower the porosity. It is preferable to convert the inorganic porous polymer film to apply the ultra-thin inorganic porous film 213a.
상기 다공성 나노섬유 웹(213)과 무기공 필름(213a)은 전해액에 팽윤이 이루어지며 전해질 이온의 전도가 가능한 고분자, 예를 들어, PVDF(폴리비닐리덴 플로라이드), PEO(Poly-Ethylene Oxide), PMMA(폴리메틸메타크릴레이트), TPU(Thermoplastic Poly Urethane) 중 어느 하나를 사용할 수 있다. The porous nanofiber web 213 and the inorganic porous film 213a are swollen in the electrolyte and are polymers capable of conducting electrolyte ions, for example, PVDF (polyvinylidene fluoride) and PEO (poly-ethylene oxide) , PMMA (polymethyl methacrylate), TPU (Thermoplastic Poly Urethane) can be used.
특히, 상기 PVDF는 기본적으로 전해액에 대한 팽윤성을 가지면서 전해질 이온의 전도가 가능하고 음극 활물질과의 접착력이 우수한 고분자로서 가장 바람직하다. In particular, the PVDF is most preferred as a polymer having a swelling property to the electrolyte and capable of conducting electrolyte ions and excellent adhesion to the negative electrode active material.
상기 PVDF는 예를 들어, VF(vinylidene fluoride)에 CTFE(Chlorotrifluoroethylene)를 15 내지 20wt% 함유한 CTFE계 PVDF 공중합물, 또는 VF(vinylidene fluoride)에 HFP(hexafluoropropylene)를 4 내지 12wt% 함유한 HFP계 PVDF 공중합물인 것이 더욱 바람직하다. The PVDF may be, for example, a CTFE-based PVDF copolymer containing 15-20 wt% of CT (Chlorotrifluoroethylene) in VF (vinylidene fluoride), or an HFP system containing 4-12 wt% of HFP (hexafluoropropylene) in VF (vinylidene fluoride) More preferred is a PVDF copolymer.
상기 CTFE계 PVDF 공중합물은 CTFE 코모노머를 15wt% 미만으로 함유하는 경우 PVDF 공중합물의 제조가 불가능하고, CTFE 코모노머를 20wt%를 초과하여 함유하는 경우 PVDF 공중합물의 내열 특성이 나빠지고 너무 부드러우며 전해질의 흡수가 너무 많아서 분리막으로 사용이 어려운 문제가 있다. The CTFE-based PVDF copolymer cannot produce PVDF copolymer when it contains less than 15 wt% of CTFE comonomer, and the heat resistance of the PVDF copolymer becomes poor and too soft when it contains more than 20 wt% of CTFE comonomer. There is a problem that is difficult to use as a separation membrane because of too much absorption.
또한, 상기 HFP계 PVDF 공중합물은 HFP 코모노머를 4wt% 미만으로 함유하는 경우 PVDF 공중합물의 제조가 불가능하고, HFP 코모노머를 12wt%를 초과하여 함유하는 경우 PVDF 공중합물의 내열 특성이 약해져서 분리막으로 사용이 어려운 문제가 있다. In addition, when the HFP-based PVDF copolymer contains less than 4wt% of HFP comonomer, it is impossible to manufacture the PVDF copolymer, and when the HFP comonomer exceeds 12wt%, the heat resistance of the PVDF copolymer is weakened and thus used as a separator. This is a difficult problem.
상기한 CTFE계 PVDF 공중합물은 Solvay Solexis에서 공급하는 Solvay Solef®PVDF Fluoropolymer Resins 중에 Solef® 32008을 사용할 수 있고, HFP계 PVDF 공중합물은 Solvay Solef® PVDF Fluoropolymer Resins 중에 Solef®21216 또는 ARKEMA KYNAR® PVDF Fluoropolymer Resins 중에 KYNAR FLEX LBG를 사용할 수 있다.The above CTFE based PVDF copolymer can use Solef ® 32008 in Solvay Solef ® PVDF Fluoropolymer Resins supplied by Solvay Solexis, and the HFP based PVDF copolymer can be used in Solvay Solef ® PVDF Fluoropolymer Resins in Solef ® 21216 or ARKEMA KYNAR ® PVDF Fluoropolymer You can use KYNAR FLEX LBG among the rests.
상기 CTFE계 PVDF 공중합물 및 HFP계 PVDF 공중합물은 각각 공중합물을 형성할 때 CTFE 또는 HFP를 포함함에 의해 PVDF 공중합물이 분리막으로 사용될 때, VF(vinylidene fluoride)의 호모폴리머로 이루어진 PVDF보다 이온전도도가 향상되는 이점이 있다.The CTFE-based PVDF copolymer and the HFP-based PVDF copolymer each contain CTFE or HFP when forming a copolymer, and thus, when the PVDF copolymer is used as a separator, ionic conductivity is higher than that of PVDF made of homopolymer of VF (vinylidene fluoride). There is an advantage that is improved.
또한, 상기 다공성 나노섬유 웹(213)은 예를 들어, 전해액에 팽윤이 이루어지며 전해질 이온의 전도가 가능한 고분자를 용매에 용해시켜 방사용액을 형성한 후, 도 10과 같이, 멀티-홀 노즐팩(221)을 사용하여 방사용액을 상기 다공성 부직포(211)의 일측면에 초극세 나노섬유(215)를 전기방사하여 초극세 섬유가 다공성 부직포(211) 위에 포집되어 다공성 나노섬유 웹을 형성한다.In addition, the porous nanofiber web 213, for example, swelling in the electrolyte solution and dissolved the polymer capable of conducting the electrolyte ions in a solvent to form a spinning solution, as shown in Figure 10, multi-hole nozzle pack The ultra-fine nanofibers 215 are electrospun on one side of the porous nonwoven fabric 211 using the spinning solution 221 to collect the ultrafine fibers on the porous nonwoven fabric 211 to form a porous nanofiber web.
상기 다공성 나노섬유 웹(213)은 초극세 나노섬유(215)로 이루어진 다공성 나노섬유 웹을 형성하고, 얻어진 다공성 나노섬유 웹을 캘린더 장치(226)에서 고분자의 융점 이하의 온도에서 캘린더링하여 형성된다.The porous nanofiber web 213 forms a porous nanofiber web made of ultrafine nanofibers 215, and is formed by calendering the obtained porous nanofiber web at a temperature below the melting point of the polymer in the calender device 226.
상기 무기공 필름(213a)의 형성은 먼저 다공성 부직포(211)의 일측면에 다공성 나노섬유 웹(213)을 형성한 후, 후속공정에서 상기 고분자(예를 들어, PVDF)의 융점 보다 낮은 온도에서 히터(225)를 이용한 표면을 열처리함에 의해 다공성 나노섬유 웹(213)을 무기공 필름(213a)으로 변환시켜서 형성할 수 있다. The inorganic porous film 213a may be formed by first forming a porous nanofiber web 213 on one side of the porous nonwoven fabric 211, and then, at a temperature lower than a melting point of the polymer (eg, PVDF) in a subsequent process. The porous nanofiber web 213 may be converted into the inorganic porous film 213a by heat-treating the surface using the heater 225.
상기 열처리 공정에서 열처리 온도가 고분자의 융점 보다 다소 낮은 온도에서 실시할 수 있는 것은 고분자 나노섬유 웹에 용매가 잔존하고 있기 때문이다.In the heat treatment process, the heat treatment temperature may be performed at a temperature slightly lower than the melting point of the polymer because the solvent remains in the polymer nanofiber web.
다공성 나노섬유 웹(213)을 구성하는 섬유의 평균 직경은 기공도 및 기공크기 분포에 매우 큰 영향을 미친다. 섬유 직경이 작을수록 기공 크기가 작아지며, 기공 크기 분포도 작아진다. 또한, 섬유의 직경이 작을수록 섬유의 비표면적이 증대되므로 전해액 보액 능력이 커지게 되므로 전해액 누액의 가능성이 줄어들게 된다. The average diameter of the fibers constituting the porous nanofiber web 213 has a great influence on porosity and pore size distribution. The smaller the fiber diameter, the smaller the pore size and the smaller the pore size distribution. In addition, as the diameter of the fiber is smaller, the specific surface area of the fiber is increased, thereby increasing the electrolyte retention capacity, thereby reducing the possibility of electrolyte leakage.
상기 다공성 나노섬유 웹(213)을 구성하는 섬유 직경은 0.3~1.5um범위이다. 무기공 필름을 형성하는 데 사용되는 다공성 나노섬유 웹(213)의 두께는 1~10㎛ 범위, 바람직하게는 3~5㎛의 초박막으로 이루어지는 것이 바람직하다.The fiber diameter constituting the porous nanofiber web 213 is in the range of 0.3 ~ 1.5um. The thickness of the porous nanofiber web 213 used to form the inorganic porous film is preferably made of an ultra-thin film in the range of 1 to 10 μm, preferably 3 to 5 μm.
초극세 섬유로 이루어진 다공성 나노섬유 웹은 초박막, 초경량으로서, 부피 대비 표면적 비가 높고, 높은 기공도를 가진다.Porous nanofiber web made of ultra-fine fibers is ultra thin, ultra-light, has a high surface area to volume ratio and high porosity.
상기 실시예에 적용된 무기공 필름(213a)은 전해액에 함침될 때 전해액에 의해 팽윤이 이루어지면서 리튬 이온의 전도가 가능하고 초박막으로 이루어져 있으므로 저항으로 작용하지 않으며, 리튬 이온의 이동도는 증가하게 된다.The inorganic porous film 213a applied to the above embodiment is capable of conducting lithium ions while being swelled by the electrolyte when it is impregnated with the electrolyte and is composed of an ultra-thin film, and thus does not act as a resistance and increases the mobility of the lithium ions. .
추후 전극 조립시에 상기와 같이 무기공 필름(213a)이 음극 활물질층의 표면에 밀착되도록 압착시키면, 전해액에 의해 팽윤이 이루어지면서 리튬 이온의 전도는 이루어지나, 음극과 분리막 사이의 공간 형성을 차단하여 리튬 이온이 쌓여서 리튬 금속으로 석출되는 현상을 방지할 수 있다. 그 결과, 음극의 표면에 덴드라이트 형성을 억제할 수 있어 안정성 향상을 도모할 수 있다.When the electrode assembly film 213a is compressed to be in close contact with the surface of the negative electrode active material layer as described above, the electrode swells by the electrolyte and conducts lithium ions, but blocks the formation of space between the negative electrode and the separator. As a result, lithium ions may be accumulated to prevent precipitation of lithium ions. As a result, dendrite formation can be suppressed on the surface of the cathode and stability can be improved.
상기 다공성 나노섬유 웹(213)을 전기방사하여 형성하기 위해 준비하는 방사용액은 내열성과 강도를 높이기 위해 무기물 입자를 소정량 포함할 수 있다. 상기 무기물 입자와 함량 등은 상기 다공성 나노섬유 웹(215)을 형성할 때와 동일하게 적용된다.The spinning solution prepared for forming the porous nanofiber web 213 by electrospinning may include a predetermined amount of inorganic particles to increase heat resistance and strength. The inorganic particles and the content are applied in the same manner as when forming the porous nanofiber web 215.
본 발명의 이차 전지는 음극과 양극 사이에 분리막을 삽입하여 압착 조립한 전극 조립체에 전해액을 포함한다. 상기 전해액은 비수성 유기용매와 리튬염의 용질을 포함한다. 상기 전해액은 도 1에 도시된 폴리머 전해질(5)을 형성할 때 사용되는 것과 동일한 것을 사용할 수 있다.The secondary battery of the present invention includes an electrolyte in an electrode assembly, which is assembled by pressing a separator between a negative electrode and a positive electrode. The electrolyte solution includes a solute of a non-aqueous organic solvent and a lithium salt. The electrolyte may be the same as that used when forming the polymer electrolyte 5 shown in FIG.
상술한 바와 같이, 전극 조립체를 조립한 후, 알루미늄 또는 알루미늄 합금 캔 또는 이와 유사한 용기에 넣은 후, 캡조립체로 개구부를 마감한 뒤 전해액을 주입하여 리튬 이차 전지를 제조한다. As described above, after assembling the electrode assembly, it is placed in an aluminum or aluminum alloy can or a similar container, the opening is closed with a cap assembly, and an electrolyte is injected to manufacture a lithium secondary battery.
상기한 캔 또는 전극 조립체를 수용하여 실링하는 케이싱에 전해액이 주입되면 PVDF 다공성 나노섬유 웹(213) 또는 무기공 필름(213a)은 전해액을 머금으면서 겔화가 이루어지면서 팽윤된다.When the electrolyte is injected into the casing that houses and seals the can or the electrode assembly, the PVDF porous nanofiber web 213 or the inorganic porous film 213a is swollen while gelling with the electrolyte.
팽윤이 이루어지는 다공성 나노섬유 웹(213) 또는 무기공 필름(213a)의 일부는 다공성 부직포(211)의 큰 기공 내부로 밀려들어가면서 다공성 부직포(211)의 일측 기공 입구를 막아서 기공도를 낮추게 된다. A portion of the porous nanofiber web 213 or the inorganic porous film 213a in which the swelling is pushed into the large pores of the porous nonwoven fabric 211 blocks the pore inlet of one side of the porous nonwoven fabric 211 to lower porosity.
특히, 상기 다공성 부직포(211)에 적층된 무기공 필름(213a)의 두께는 각각 1 내지 10um 범위, 바람직하게는 3내지 5㎛의 초박막으로 이루어지므로 전해액이 주입되어 함침되면 팽윤이 이루어지면서 미세기공이 형성되어 리튬 이온의 이동이 가능하게 된다. 그 결과 마이크로 쇼트는 발생하지 않으면서 OCV 특성이 크게 개선될 수 있다.In particular, the thickness of the non-porous film 213a laminated on the porous nonwoven fabric 211 is made of an ultra-thin film of 1 to 10um range, preferably 3 to 5㎛ each, so that when the electrolyte is injected and impregnated, the micropores Is formed to allow the movement of lithium ions. As a result, OCV characteristics can be greatly improved without micro shorts occurring.
또한, 상기 다공성 부직포(211)에 적층된 다공성 나노섬유 웹(213)은 전해액이 주입되어 함침되면 나노섬유 웹의 나노섬유가 약 500배 팽윤되어 기공이 크기가 축소되면서 필름화가 이루어진다. 그 결과, 나노섬유 웹의 미세기공을 통한 리튬 이온의 이동은 가능하게 되며, 마이크로 쇼트의 발생은 차단하여 OCV 특성이 크게 개선될 수 있다.In addition, when the porous nanofiber web 213 laminated on the porous nonwoven fabric 211 is impregnated with an electrolyte solution, the nanofibers of the nanofiber webs swell about 500 times, and the pores are reduced in size to form a film. As a result, the movement of lithium ions through the micropores of the nanofiber web is possible, and the generation of micro shorts can be blocked to significantly improve the OCV characteristics.
더욱이, 본 발명에서는 기재로서 상기 다공성 부직포(211)를 사용하고, 부직포의 일측이 PVDF 무기공 필름(213a)으로 이루어지므로, 밀착성이 우수한 상기 무기공 필름(213a)은 음극의 표면에 밀착되어 조립되므로, 덴드라이트 형성을 억제하는 역할을 한다.Furthermore, in the present invention, since the porous nonwoven fabric 211 is used as a substrate, and one side of the nonwoven fabric is made of the PVDF inorganic porous film 213a, the inorganic porous film 213a having excellent adhesion is adhered to the surface of the negative electrode and assembled. Therefore, it plays a role of suppressing dendrite formation.
본 발명의 바람직한 실시예에 따른 복합 다공성 분리막(210)은 예를 들어, 도 1에 도시된 바와 같이, 양극, 무기공 타입의 겔형 폴리머 전해질 및 음극을 포함하는 리튬 폴리머 전지에도 적용될 수 있다.The composite porous separator 210 according to the preferred embodiment of the present invention may be applied to a lithium polymer battery including, for example, a positive electrode, a gel polymer electrolyte of an inorganic type, and a negative electrode, as shown in FIG. 1.
이 경우, 상기 폴리머 전해질은, 다공성 부직포(211)와, 다수의 나노 섬유(215)로 이루어진 다공성 나노섬유 웹(213)이 적층된 복합 다공성 분리막(210)을 이용한다. 상기 나노섬유(215)는 도 1에 도시된 나노섬유(150)와 동일하게 비팽윤성 폴리머 코어의 외부에 팽윤성 폴리머 쉘이 둘러싸는 코어-쉘 구조를 형성하도록 팽윤성 폴리머와 비팽윤성 폴리머를 혼합한 혼합 폴리머를 방사용액으로 사용한다. 상기 혼합 폴리머는 예를 들어, PVDF와 PAN과 같이 팽윤성 폴리머와 비팽윤성 폴리머 사이의 분자량 차이가 적어도 20배 이상이 되도록 조합한다.In this case, the polymer electrolyte uses a composite porous separator 210 in which a porous nonwoven fabric 211 and a porous nanofiber web 213 made of a plurality of nanofibers 215 are stacked. The nanofiber 215 is a mixture of a swellable polymer and a non-swellable polymer mixed to form a core-shell structure surrounded by a swellable polymer shell on the outside of the non-swellable polymer core in the same manner as the nanofiber 150 shown in FIG. 1. Polymer is used as spinning solution. The mixed polymers are combined such that, for example, the molecular weight difference between the swellable polymer and the non-swellable polymer, such as PVDF and PAN, is at least 20 times or more.
그 후, 상기한 혼합 폴리머로 이루어진 다공성 나노섬유 웹(213)과 다공성 부직포(211)가 적층된 복합 다공성 분리막(210)을 사용하여 도 1 또는 도 5와 같이, 봉지화하고 양극 및 음극이 조립된 전극 조립체를 준비한 후, 전극 조립체를 케이싱하고 전해액을 주입한 후, 겔화 열처리를 실시하면 양극과 음극 사이에 겔형 폴리머 전해질이 형성된다.Thereafter, using the composite porous membrane 210 in which the porous nanofiber web 213 made of the mixed polymer and the porous nonwoven fabric 211 are stacked, as shown in FIG. 1 or 5, the anode and the cathode are assembled. After the prepared electrode assembly is prepared, the electrode assembly is cased, an electrolyte solution is injected, and gelation heat treatment is performed to form a gel polymer electrolyte between the positive electrode and the negative electrode.
이하에 도 10 및 도 11을 참고하여 본 발명의 복합 다공성 분리막의 제조방법을 설명한다.Hereinafter, a method of manufacturing the composite porous separator of the present invention will be described with reference to FIGS. 10 and 11.
본 발명의 실시예에 따른 복합 다공성 분리막(210)은 도 10에 도시된 바와 같이, 먼저 전해액에 팽윤이 이루어지며 전해질 이온의 전도가 가능한 고분자를 용매에 용해시켜 방사용액을 준비한다. In the composite porous membrane 210 according to the embodiment of the present invention, as shown in FIG. 10, first, a swelling is performed in an electrolyte and a spinning solution is prepared by dissolving a polymer capable of conducting electrolyte ions in a solvent.
그 후, 멀티-홀 노즐팩(221)을 사용하여 예를 들어, 에어 전기방사(AES: Air-electrospinning) 방법으로 방사용액을 하측의 콜렉터(223)를 따라 이송되는 상기 다공성 부직포(11)의 일측면에 초극세 나노섬유(215)를 전기방사하여 다공성 나노섬유 웹(230)을 형성하여 2층 구조의 적층체를 형성한다.Thereafter, the multi-hole nozzle pack 221 is used, for example, of the porous nonwoven fabric 11 to which the spinning solution is transported along the collector 223 on the lower side by air-electrospinning (AES). Ultrafine nanofibers 215 are electrospun on one side to form a porous nanofiber web 230 to form a laminate having a two-layer structure.
본 발명의 에어 전기방사(AES) 방법은 고분자 용액이 방사되는 멀티-홀 노즐팩(221)의 방사노즐과 콜렉터(223) 사이에 90~120Kv의 고전압 정전기력을 인가함에 의해 콜렉터(223)에 초극세 나노섬유(215)가 방사되어 다공성 나노섬유 웹(230)을 형성하며, 이 경우 각 방사노즐마다 에어를 분사함에 의해 방사된 섬유가 콜렉터(223)에 포집되지 못하고 날리는 것을 잡아주는 방사방법이다. Air electrospinning (AES) method of the present invention is ultra-fine to the collector 223 by applying a high voltage electrostatic force of 90 ~ 120Kv between the spinneret and the collector 223 of the multi-hole nozzle pack 221 in which the polymer solution is radiated The nanofibers 215 are spun to form a porous nanofiber web 230, in this case is a spinning method that catches the flying fibers are not collected in the collector 223 by spraying air for each spinning nozzle.
상기 2층 구조의 적층체는 캘린더 장치(226)에서 캘린더링이 이루어져서 적층체의 두께 조절이 이루어지면, 도 8과 같은 다공성 부직포(211)와 다공성 고분자 나노섬유 웹(213)으로 이루어진 복합 다공성 분리막(210)이 얻어진다.When the laminate of the two-layer structure is calendered in the calender device 226 and the thickness of the laminate is controlled, the composite porous separator composed of the porous nonwoven fabric 211 and the porous polymer nanofiber web 213 as shown in FIG. 210 is obtained.
한편, 상기 다공성 부직포(211)의 일측면에 다른 실시예에 따라 복합 다공성 분리막(210a)을 제조하는 경우, 다공성 부직포(211)의 일측면에 다공성 나노섬유 웹(230)을 적층하고, 다공성 나노섬유 웹(230)을 히터(225)에 노출된 상태로 이송시키면, 다공성 나노섬유 웹(230)은 무기공 필름(213a)으로 변환된다.On the other hand, when manufacturing the composite porous membrane 210a according to another embodiment on one side of the porous nonwoven fabric 211, the porous nanofiber web 230 is laminated on one side of the porous nonwoven fabric 211, porous nano When the fibrous web 230 is transferred to the heater 225, the porous nanofiber web 230 is converted into the inorganic porous film 213a.
이어서, 상기 2층 구조의 적층체는 캘린더 장치(226)에서 캘린더링이 이루어져서 적층체의 두께 조절이 이루어지면, 도 9와 같은 다공성 부직포(211)와 무기공 필름(13a)으로 이루어진 복합 다공성 분리막(210a)이 얻어진다.Subsequently, when the laminate of the two-layer structure is calendered in the calender device 226 and the thickness of the laminate is controlled, the composite porous separator composed of the porous nonwoven fabric 211 and the inorganic porous film 13a as shown in FIG. 210a is obtained.
그러나, 본 발명에 따른 복합 다공성 분리막의 제조공정은 도 11에 도시된 바와 같이, 전사방법을 이용하여 멀티-홀 노즐팩(221)으로부터 방사용액을 하측의 콜렉터(223)를 따라 이송되는 트랜스퍼 시트(211a)의 일측면에 초극세 나노섬유(215)를 전기방사하여 초극세 나노섬유로 이루어진 다공성 나노섬유 웹(230)을 형성한다.However, in the manufacturing process of the composite porous membrane according to the present invention, as shown in Figure 11, the transfer sheet for transferring the spinning solution from the multi-hole nozzle pack 221 along the lower collector 223 using a transfer method The ultrafine nanofibers 215 are electrospun on one side of 211a to form a porous nanofiber web 230 made of ultrafine nanofibers.
상기 트랜스퍼 시트(211a)는 예를 들어, 종이, 또는 방사용액의 방사시에 이에 포함된 용매에 의해 용해가 이루어지지 않는 고분자 재료로 이루어진 부직포, PE, PP 등의 폴리올레핀계 필름을 사용할 수 있다. 다공성 나노섬유 웹 자체만으로 이루어진 경우 인장강도가 낮아서 높은 이송속도를 가지고 이송되면서 건조 공정, 캘린더링 공정 및 권선 공정이 이루어지는 것이 어렵다.The transfer sheet 211a may be, for example, a paper or a polyolefin-based film such as nonwoven fabric, PE, PP, or the like made of a polymer material which is not dissolved by a solvent contained therein during spinning of the spinning solution. In the case of the porous nanofiber web itself, it is difficult to carry out a drying process, a calendering process, and a winding process while being transferred at a high feed rate due to low tensile strength.
더욱이, 다공성 나노섬유 웹을 제조한 후 후속된 양극 또는 음극과의 봉지 공정을 높은 이송속도를 가지고 연속적으로 실행되기 어려우나 상기한 트랜스퍼 시트(211a)를 이용하는 경우 충분한 인장강도를 제공함에 따라 공정처리 속도를 크게 높일 수 있다. Moreover, it is difficult to carry out the encapsulation process with the positive or negative electrode subsequent to the fabrication of the porous nanofiber web continuously with a high feed rate, but in the case of using the transfer sheet 211a as described above, it provides sufficient tensile strength. Can greatly increase.
또한, 다공성 나노섬유 웹만을 사용하는 경우 정전기로 인하여 타 물체에 들러붙는 현상이 발생하여 작업성이 떨어지게 되나, 트랜스퍼 시트(211a)를 이용하는 경우 이러한 문제를 해결할 수 있다. In addition, when only the porous nanofiber web is used, the phenomenon of sticking to other objects occurs due to static electricity, resulting in poor workability, but when the transfer sheet 211a is used, this problem can be solved.
더욱이, 전기방사되는 나노섬유는 콜렉터에서 집적 현상이 일어나며 집적부의 패턴을 따라가며 적층되는 현상이 있다(ex. 다이아몬드 패턴위에 방사하면 최초 다이아몬드 패턴을 따라 나노섬유가 집적되기 시작함).Moreover, the electrospun nanofibers develop in the collector and are stacked along the pattern of the integrated part (ex. When the nanofibers are radiated onto the diamond pattern, the nanofibers begin to accumulate along the initial diamond pattern).
따라서, 균일도(기공크기, 통기도, 두께, 중량 등)가 좋은 나노섬유의 다공성 나노섬유 웹을 만들기 위해서는 부직포보다 종이에 방사하는 것이 더 적합하다.Therefore, in order to make a porous nanofiber web of nanofibers having good uniformity (pore size, air permeability, thickness, weight, etc.), spinning on paper is more suitable than nonwoven fabric.
부직포에 바로 방사하여 캘린더링하는 경우 부직포의 녹는점 때문에 캘린더링 온도의 제어에 제한을 받는다. PVdF 섬유 사이의 결합온도는 약 150도이나, 부직포의 녹는점은 이보다 낮은 110~130도이다. 따라서, 나노섬유의 다공성 나노섬유 웹을 종이에 방사하여 약 150도에서 1차 캘린더링(calendaring)을 실시하고, 1차 캘린더링 온도보다 낮은 온도에서 2차 캘린더링에 의해 부직포와 합지가 이루어지면, 섬유와 섬유간의 견고한 결합을 만들 수 있어, 완성도 높은 다공성 나노섬유 웹을 만들게 된다.In the case of calendaring by spinning directly on the nonwoven fabric, the melting point of the nonwoven fabric is limited by the control of the calendering temperature. The bonding temperature between PVdF fibers is about 150 degrees, but the melting point of nonwoven fabrics is 110 to 130 degrees. Therefore, when the porous nanofiber web of nanofibers is spun onto paper, primary calendering is performed at about 150 degrees, and the nonwoven fabric is laminated by secondary calendering at a temperature lower than the primary calendering temperature. The result is a strong bond between fibers, creating a highly porous nanofiber web.
또한, 종이와 같은 트랜스퍼 시트를 사용하여 나노섬유의 다공성 나노섬유 웹을 형성하는 경우, 종이는 나노섬유 웹에 포함된 잔류용제(solvent)를 흡수함으로써 나노섬유가 잔류용제에 의해 다시 녹는 현상을 막아주고 또한 잔류용제의 양을 적절하게 조절할 수 있도록 하는 역할을 할 수 있다.In addition, when forming a porous nanofiber web of nanofibers using a transfer sheet such as paper, the paper absorbs the solvent contained in the nanofiber web to prevent the nanofibers from re-melting by the residual solvent. It can also serve to control the amount of residual solvent appropriately.
상기 트랜스퍼 시트(211a)에 형성된 다공성 나노섬유 웹(230)은 그 후, 용매가 잔류상태에서 얻어진 다공성 나노섬유 웹(230)을 다공성 부직포(211)의 일측면에 합지하여, 캘린더 장치(226)에서 캘린더링함에 의해 실시예에 따른 2층 구조의 복합 다공성 분리막(210)을 형성하는 것도 가능하다. 상기 트랜스퍼 시트(211a)는 도 11과 같이 합지 공정 이후에 박리되어 제거된다.The porous nanofiber web 230 formed on the transfer sheet 211a is then laminated on one side of the porous nonwoven fabric 211 with the porous nanofiber web 230 obtained in a solvent remaining state, and the calender apparatus 226. It is also possible to form the composite porous separator 210 of the two-layer structure according to the embodiment by calendering in. The transfer sheet 211a is peeled off and removed after the lamination process as shown in FIG. 11.
본 발명에 따른 다공성 분리막의 제조에 사용 가능한 방사방법으로는 에어 전기방사(AES: Air-Electrospinning) 이외에 일반적인 전기방사(electrospinning), 전기분사(electrospray), 전기분사방사(electrobrown spinning), 원심전기방사(centrifugal electrospinning), 플래쉬 전기방사(flash-electrospinning) 중 어느 하나를 사용할 수 있다.The spinning method usable in the preparation of the porous separator according to the present invention includes general electrospinning, electrospray, electrobrown spinning, and centrifugal electrospinning in addition to air electrospinning (AES). (centrifugal electrospinning) or flash-electrospinning can be used.
본 발명에서 사용하는 멀티-홀 방사팩 노즐은 에어 전기방사(AES: Air-Electrospinning)를 이용할 때 에어 분사의 에어압이 0.1~0.6MPa 범위로 설정된다. In the multi-hole spinning pack nozzle used in the present invention, the air pressure of the air jet is set in the range of 0.1 to 0.6 MPa when using air electrospinning (AES).
본 발명에서는 단일 용매를 사용할 때는 고분자의 종류에 따라 용매의 휘발이 잘 이루어지지 못하는 경우가 있다는 것을 고려하여 방사공정 이후에 프리 히터(225)에 의한 선 건조구간(Pre-Air Dry Zone)을 통과하면서 다공성 나노섬유 웹의 표면에 잔존해 있는 용매와 수분의 양을 조절하는 공정을 거칠 수 있다.In the present invention, when using a single solvent, considering that the solvent may not be volatilized well depending on the type of polymer, it passes through a pre-air dry zone by the pre-heater 225 after the spinning process. While controlling the amount of solvent and water remaining on the surface of the porous nanofiber web may be processed.
프리 히터에 의한 선 건조구간은 20~40℃의 에어를 팬(fan)을 이용하여 나노섬유 웹에 인가하여 다공성 나노섬유 웹의 표면에 잔존해 있는 용매와 수분의 양을 조절함에 의해 다공성 나노섬유 웹이 벌키(bulky)해지는 것을 방지하여 분리막의 강도를 증가시켜주는 역할과 동시에 다공성(Porosity)을 조절할 수 있게 된다. Pre-heating section by pre-heater is applied to the nanofiber web by applying air of 20 ~ 40 ℃ to the nanofiber web to control the amount of solvent and moisture remaining on the surface of the porous nanofiber web. By preventing the web from becoming bulky, the role of increasing the strength of the separator and the porosity can be controlled.
이 경우, 용매의 휘발이 지나치게 많이 된 상태에서 캘린더링이 이루어지면 다공성은 증가하나 나노섬유웹의 강도가 약해지고, 반대로 용매의 휘발이 적게 되면 나노섬유 웹이 녹는 현상이 발생하게 된다.In this case, if calendering is performed in a state in which the volatilization of the solvent is excessive, the porosity increases but the strength of the nanofiber web is weakened. On the contrary, when the volatilization of the solvent is reduced, the nanofiber web melts.
다공성 나노섬유 웹으로 이루어진 단층 또는 다층 구조의 분리막은 인장강도가 낮기 때문에 본 발명과 같이 상대적으로 인장강도가 높은 부직포로 이루어지는 다공성 부직포를 지지체로서 사용하면 분리막의 인장강도를 높일 수 있다.Since the membrane having a single layer or multilayer structure made of porous nanofiber web has low tensile strength, when the porous nonwoven fabric made of a nonwoven fabric having a relatively high tensile strength is used as a support, the tensile strength of the membrane can be increased.
상기 실시예 설명에서는 복합 다공성 분리막(210,210a)이 다공성 부직포(211)의 일측면에 다공성 나노섬유 웹(213) 또는 무기공 필름(213a)이 적층된 2층 구조로 이루어진 것을 예시하였으나, 필요에 따라 다공성 부직포(211)의 양측면에 무기공 필름(213a)이 각각 적층된 3층 구조로 이루어지는 것도 가능하다.In the above description, the composite porous separators 210 and 210a have a two-layer structure in which the porous nanofiber web 213 or the inorganic porous film 213a is laminated on one side of the porous nonwoven fabric 211. Accordingly, it is also possible to have a three-layer structure in which the inorganic porous films 213a are laminated on both sides of the porous nonwoven fabric 211.
이상에서는 본 발명을 특정의 바람직한 실시예를 예를 들어 도시하고 설명하였으나, 본 발명은 상기한 실시예에 한정되지 아니하며 본 발명의 정신을 벗어나지 않는 범위내에서 당해 발명이 속하는 기술분야에서 통상의 지식을 가진 자에 의해 다양한 변경과 수정이 가능할 것이다.In the above, the present invention has been illustrated and described with reference to specific preferred embodiments, but the present invention is not limited to the above-described embodiments, and the present invention is not limited to the spirit of the present invention. Various changes and modifications will be possible by those who have the same.
본 발명은 다공성 나노섬유 웹을 구성하는 나노섬유가 쉘-코어 구조를 형성하며 외측에 배치되는 팽윤성 폴리머 쉘은 전해액에 의해 겔화가 이루어질지라도 내측에 배치되는 비팽윤성 폴리머 코어에 의해 균일한 웹 형상을 유지함에 따라 양 전극 사이의 단락을 방지하여, 안전성과 박막화를 동시에 도모할 수 있는 폴리머 전해질을 구비하는 리튬 이온 폴리머 전지에 적용될 수 있다.According to the present invention, the nanofibers constituting the porous nanofiber web form a shell-core structure, and the outer swellable polymer shell has a uniform web shape by the non-swellable polymer core disposed inside even though gelation is performed by the electrolyte. It can be applied to a lithium ion polymer battery provided with a polymer electrolyte which can prevent short circuit between both electrodes by holding, and can simultaneously aim at safety and thinning.

Claims (20)

  1. 지지체 역할을 하며 미세기공을 갖는 다공성 부직포; 및A porous nonwoven fabric serving as a support and having micropores; And
    상기 다공성 부직포의 일측면에 적층되며, 대향하는 전극과 밀착될 때 접착층 및 이온함습층 역할을 하는 다공성 나노섬유 웹을 포함하며,It is laminated on one side of the porous nonwoven fabric, and includes a porous nanofiber web that serves as an adhesive layer and an ion-moisture layer when in close contact with the opposite electrode,
    상기 다공성 나노섬유 웹의 일부는 다공성 부직포의 기공을 부분적으로 차단하도록 다공성 부직포의 표면층에 함입되어 다공성 부직포의 기공도를 낮추는 것을 특징으로 하는 다공성 분리막.A portion of the porous nanofiber web is embedded in the surface layer of the porous nonwoven fabric to partially block the pores of the porous nonwoven fabric porous membrane, characterized in that to reduce the porosity of the porous nonwoven fabric.
  2. 제1항에 있어서, 상기 다공성 나노섬유 웹은 전해액에 팽윤이 이루어지며 전해질 이온의 전도가 가능한 고분자로 이루어지는 것을 특징으로 하는 다공성 분리막.The porous membrane of claim 1, wherein the porous nanofiber web is swelled in an electrolyte and made of a polymer capable of conducting electrolyte ions.
  3. 제2항에 있어서, 상기 고분자는 PVDF, PEO, PMMA, TPU 중 어느 하나인 것을 특징으로 하는 다공성 분리막.The porous membrane of claim 2, wherein the polymer is any one of PVDF, PEO, PMMA, and TPU.
  4. 제2항에 있어서, 상기 고분자는 CTFE(Chlorotrifluoroethylene)계 PVDF 공중합물 또는 HFP(hexafluoropropylene)계 PVDF 공중합물인 것을 특징으로 하는 다공성 분리막.The porous membrane of claim 2, wherein the polymer is a CTFE (Chlorotrifluoroethylene) PVDF copolymer or an HFP (hexafluoropropylene) PVDF copolymer.
  5. 제4항에 있어서, 상기 CTFE계 PVDF 공중합물은 VF(vinylidene fluoride)에 CTFE를 15 내지 20wt% 함유하며, HFP계 PVDF 공중합물은 VF에 HFP를 4 내지 12wt% 함유한 것을 특징으로 하는 다공성 분리막.The porous membrane of claim 4, wherein the CTFE PVDF copolymer contains 15 to 20 wt% of CTFE in VF (vinylidene fluoride), and the HFP PVDF copolymer contains 4 to 12 wt% of HFP in VF. .
  6. 제1항에 있어서, 상기 다공성 나노섬유 웹의 두께는 1 내지 10um 범위로 설정되고, 상기 다공성 부직포의 두께는 10 내지 40um 범위로 설정되는 것을 특징으로 하는 다공성 분리막.The porous membrane of claim 1, wherein a thickness of the porous nanofiber web is set in a range of 1 to 10 μm, and a thickness of the porous nonwoven fabric is set in a range of 10 to 40 μm.
  7. 제1항에 있어서, 상기 다공성 부직포는 코어로서 PP 섬유의 외주에 PE가 코팅된 이중 구조의 PP/PE 섬유로 이루어진 부직포, 폴리에틸렌테레프탈레이트(PET) 섬유로 이루어진 PET 부직포, 셀룰로즈 섬유로 이루어진 부직포 중 어느 하나인 것을 특징으로 하는 다공성 분리막.The nonwoven fabric of claim 1, wherein the porous nonwoven fabric is a nonwoven fabric made of a double structure PP / PE fiber coated with PE on the outer circumference of the PP fiber as a core, a PET nonwoven fabric made of polyethylene terephthalate (PET) fiber, and a nonwoven fabric made of cellulose fiber. Porous separator, characterized in that any one.
  8. 제1항에 있어서, 상기 다공성 나노섬유 웹은 각각 길이방향을 따라 쉘-코어 구조를 이루는 다수의 나노섬유를 포함하며, The method of claim 1, wherein the porous nanofiber web comprises a plurality of nanofibers each forming a shell-core structure along the longitudinal direction,
    상기 다수의 나노섬유 각각은 외측에 배치되며 유기 전해액에 팽윤이 이루어지는 팽윤성 폴리머로 이루어지는 팽윤성 폴리머 쉘과 비팽윤성 폴리머로 이루어진 비팽윤성 폴리머 코어를 포함하는 것을 특징으로 하는 다공성 분리막.Each of the plurality of nanofibers is disposed on the outside and porous separator characterized in that it comprises a swellable polymer shell consisting of a swellable polymer shell and a non-swellable polymer made of swellable polymer swelling in the organic electrolyte.
  9. 제8항에 있어서, 상기 팽윤성 폴리머와 비팽윤성 폴리머 사이의 분자량 차이가 20배 이상인 것을 특징으로 하는 다공성 분리막.The porous membrane of claim 8, wherein the molecular weight difference between the swellable polymer and the non-swellable polymer is 20 times or more.
  10. 제8항에 있어서, 상기 다공성 나노섬유 웹은 40~90중량% 비팽윤성 폴리머와 10~60중량%의 팽윤성 폴리머를 포함하는 것을 특징으로 하는 다공성 분리막.The porous membrane of claim 8, wherein the porous nanofiber web comprises 40 to 90 wt% non-swellable polymer and 10 to 60 wt% swellable polymer.
  11. 지지체 역할을 하며 미세기공을 갖는 다공성 부직포; 및A porous nonwoven fabric serving as a support and having micropores; And
    상기 다공성 부직포의 일측면에 적층되며, 대향하는 전극과 밀착될 때 접착층 및 이온함습층 역할을 하는 무기공 필름을 포함하며,It is laminated on one side of the porous non-woven fabric, and includes an inorganic porous film that serves as an adhesive layer and an ion-moisture layer when in close contact with the opposite electrode,
    상기 무기공 필름의 일부는 다공성 부직포의 기공을 차단하도록 다공성 부직포의 표면층에 함입되는 것을 특징으로 하는 다공성 분리막.And a portion of the inorganic porous film is embedded in the surface layer of the porous nonwoven fabric to block pores of the porous nonwoven fabric.
  12. 양극, 음극, 상기 양극과 음극을 분리시키는 분리막 및 전해액을 포함하며,A positive electrode, a negative electrode, a separator and an electrolyte separating the positive electrode and the negative electrode,
    상기 분리막은 The separator is
    지지체 역할을 하며 미세기공을 갖는 다공성 부직포; 및A porous nonwoven fabric serving as a support and having micropores; And
    상기 다공성 부직포의 일측면에 적층되며, 대향하는 전극과 밀착될 때 접착층 및 이온함습층 역할을 하는 다공성 나노섬유 웹을 포함하며,It is laminated on one side of the porous nonwoven fabric, and includes a porous nanofiber web that serves as an adhesive layer and an ion-moisture layer when in close contact with the opposite electrode,
    상기 다공성 나노섬유 웹의 일부는 다공성 부직포의 기공을 부분적으로 차단하도록 다공성 부직포의 표면층에 함입되어 다공성 부직포의 기공도를 낮추는 것을 특징으로 하는 이차전지.Part of the porous nanofiber web is embedded in the surface layer of the porous nonwoven fabric to partially block the pores of the porous nonwoven fabric secondary battery, characterized in that to reduce the porosity of the porous nonwoven fabric.
  13. 제12항에 있어서, 상기 다공성 나노섬유 웹은 전해액에 팽윤이 이루어지며 전해질 이온의 전도가 가능한 고분자로 이루어지며, The method of claim 12, wherein the porous nanofiber web is made of a polymer that swells in the electrolyte and is capable of conducting electrolyte ions,
    상기 고분자는 CTFE(Chlorotrifluoroethylene)계 PVDF 공중합물 또는 HFP(hexafluoropropylene)계 PVDF 공중합물인 것을 특징으로 하는 이차전지.The polymer is a secondary battery, characterized in that the CTFE (Chlorotrifluoroethylene) PVDF copolymer or HFP (hexafluoropropylene) PVDF copolymer.
  14. 제12항에 있어서, 상기 다공성 나노섬유 웹은 각각 길이방향을 따라 쉘-코어 구조를 이루는 다수의 나노섬유를 포함하며, The method of claim 12, wherein the porous nanofiber web comprises a plurality of nanofibers each forming a shell-core structure along the longitudinal direction,
    상기 다수의 나노섬유 각각은 외측에 배치되며 전해액에 팽윤이 이루어지는 팽윤성 폴리머로 이루어지는 팽윤성 폴리머 쉘과 비팽윤성 폴리머로 이루어진 비팽윤성 폴리머 코어를 포함하는 것을 특징으로 하는 이차전지.Each of the plurality of nanofibers is disposed on the outside and the secondary battery comprising a swellable polymer shell made of a swellable polymer swelling the electrolyte and a non-swellable polymer core made of a non-swellable polymer.
  15. 제14항에 있어서, 상기 다공성 나노섬유 웹은 리튬염이 비수성 유기용매에 용해된 전해액에 함침된 후, 겔화 공정이 이루어짐에 따라 상기 나노섬유의 외측에 배치되는 팽윤성 폴리머 쉘은 전해액에 의해 겔화가 이루어지고, 내측에 배치되는 비팽윤성 폴리머 코어는 웹 형상을 유지하는 것을 특징으로 하는 이차전지. The swellable polymer shell of claim 14, wherein the porous nanofiber web is impregnated with an electrolyte solution in which a lithium salt is dissolved in a non-aqueous organic solvent and then gelled by the electrolyte solution. And a non-swellable polymer core disposed inside the secondary battery, characterized in that it maintains a web shape.
  16. 제15항에 있어서, 상기 다공성 나노섬유 웹은 겔화 공정이 이루어짐에 따라 폴리머 전해질을 구성하는 것을 특징으로 하는 이차전지. The secondary battery of claim 15, wherein the porous nanofiber web forms a polymer electrolyte according to a gelation process.
  17. 제16항에 있어서, 상기 양극과 음극은 각각 교대로 적층되는 다수의 단위 전극셀로 이루어지고, 상기 폴리머 전해질로 분리되며,17. The method of claim 16, wherein the positive electrode and the negative electrode is composed of a plurality of unit electrode cells are each alternately stacked, separated into the polymer electrolyte,
    상기 폴리머 전해질에 의해 분리되어 적층된 다수의 양극 및 음극 단위 셀이 적층방향으로 팽창되는 것을 차단하기 위한 압박밴드를 더 포함하는 것을 특징으로 하는 이차전지.The secondary battery further comprises a compression band for blocking the expansion of the plurality of positive electrode and negative electrode unit cells separated and stacked by the polymer electrolyte in the stacking direction.
  18. 각각 비팽윤성 폴리머와 팽윤성 폴리머로 이루어진 다수의 나노섬유를 구비하는 한쌍의 다공성 나노섬유 웹을 사용하여 다수의 단위 양극셀과 다수의 단위 음극셀을 분리하면서 교대로 적층된 전극 조립체; An electrode assembly alternately stacked while separating a plurality of unit anode cells and a plurality of unit cathode cells by using a pair of porous nanofiber webs each having a plurality of nanofibers composed of a non-swellable polymer and a swellable polymer;
    상기 전극 조립체의 외주를 테이핑하는 압박밴드; 및A compression band taping the outer circumference of the electrode assembly; And
    상기 압박밴드로 테이핑된 전극 조립체를 내장하며, 전해액이 주입된 케이스를 포함하며,Built-in electrode assembly taped to the compression band, and includes a case in which the electrolyte is injected,
    겔화 공정이 이루어짐에 따라 상기 나노섬유의 외측에 배치되는 팽윤성 폴리머 쉘은 전해액에 의해 겔화가 이루어지고, 내측에 배치되는 비팽윤성 폴리머 코어는 웹 형상을 유지하는 것을 특징으로 하는 이차전지.As the gelation process is performed, the swellable polymer shell disposed on the outside of the nanofibers is gelled by an electrolyte, and the non-swellable polymer core disposed on the inside maintains a web shape.
  19. 팽윤성 폴리머와 비팽윤성 폴리머를 용매에 용해시켜 혼합 폴리머 방사용액을 형성하는 단계; Dissolving the swellable polymer and the non-swellable polymer in a solvent to form a mixed polymer spinning solution;
    상기 혼합 폴리머 방사용액을 방사하여 상기 팽윤성 폴리머와 비팽윤성 폴리머가 쉘-코어 구조를 형성하는 다수의 나노섬유로 이루어진 다공성 나노섬유 웹을 형성하는 단계; Spinning the mixed polymer spinning solution to form a porous nanofiber web composed of a plurality of nanofibers in which the swellable polymer and the non-swellable polymer form a shell-core structure;
    각각 다수의 단위 전극셀로 이루어지는 양극과 음극 사이에 상기 다공성 나노섬유 웹을 삽입하여 전극 조립체를 형성하는 단계; Forming an electrode assembly by inserting the porous nanofiber web between an anode and a cathode each consisting of a plurality of unit electrode cells;
    상기 전극 조립체를 케이스에 내장하고 전해액을 주입하는 단계; 및 Embedding the electrode assembly in a case and injecting an electrolyte solution; And
    겔화 열처리를 실시하여, 상기 나노섬유의 외측에 배치되는 팽윤성 폴리머 쉘을 전해액에 의해 팽윤시키는 단계를 포함하며,Performing a gelling heat treatment to swell the swellable polymer shell disposed outside the nanofibers with an electrolyte solution,
    상기 나노섬유의 내측에 배치되는 비팽윤성 폴리머 코어는 웹 형상을 유지하는 것을 특징으로 하는 이차전지의 제조방법.The non-swellable polymer core disposed inside the nanofibers maintains a web shape.
  20. 제19항에 있어서, 상기 다공성 나노섬유 웹은 상기 혼합 폴리머 방사용액을 스트립형 트랜스퍼 시트에 방사하여 형성되며, The method of claim 19, wherein the porous nanofiber web is formed by spinning the mixed polymer spinning solution to the strip-shaped transfer sheet,
    상기 전극 조립체를 형성하는 단계는 Forming the electrode assembly
    상기 다수의 단위 전극셀을 연속적으로 이송하면서 양면에 한쌍의 다공성 나노섬유 웹으로 봉지하는 단계; 및 Encapsulating the pair of porous nanofiber webs on both sides while continuously transporting the plurality of unit electrode cells; And
    상기 봉지 단계 이후에 한쌍의 다공성 나노섬유 웹으로부터 트랜스퍼 시트를 각각 분리시키는 단계를 더 포함하는 것을 특징으로 하는 이차전지의 제조방법.After the encapsulation step further comprises the step of separating the transfer sheet from the pair of porous nanofiber web, respectively.
PCT/KR2013/011952 2012-12-21 2013-12-20 Porous separation membrane, secondary battery using same, and method for manufacturing said secondary battery WO2014098519A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
US14/743,043 US9647255B2 (en) 2012-12-21 2015-06-18 Porous separation membrane, secondary battery using same, and method for manufacturing said secondary battery

Applications Claiming Priority (6)

Application Number Priority Date Filing Date Title
KR1020120151137A KR101576144B1 (en) 2012-12-21 2012-12-21 Polymer Electrolyte, Lithium Secondary Battery Using the Same and Manufacturing Method thereof
KR10-2012-0151137 2012-12-21
KR10-2013-0082008 2013-07-12
KR20130082008 2013-07-12
KR10-2013-0131035 2013-10-31
KR1020130131035A KR101576151B1 (en) 2013-07-12 2013-10-31 Complex fibrous separator, manufacturing method thereof and secondary battery using the same

Related Child Applications (1)

Application Number Title Priority Date Filing Date
US14/743,043 Division US9647255B2 (en) 2012-12-21 2015-06-18 Porous separation membrane, secondary battery using same, and method for manufacturing said secondary battery

Publications (1)

Publication Number Publication Date
WO2014098519A1 true WO2014098519A1 (en) 2014-06-26

Family

ID=50978745

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/KR2013/011952 WO2014098519A1 (en) 2012-12-21 2013-12-20 Porous separation membrane, secondary battery using same, and method for manufacturing said secondary battery

Country Status (1)

Country Link
WO (1) WO2014098519A1 (en)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPWO2016110894A1 (en) * 2015-01-09 2017-10-19 日本ゼオン株式会社 Nonaqueous secondary battery separator, method for producing the same, and nonaqueous secondary battery
CN110048158A (en) * 2019-04-25 2019-07-23 北京卫蓝新能源科技有限公司 A kind of in-situ polymerization ELECTRODE WITH BILAYER POLYMERIC object dielectric film and its preparation method and application
CN111106381A (en) * 2018-10-25 2020-05-05 深圳市比亚迪锂电池有限公司 Polymer electrolyte, preparation method thereof and lithium ion battery
CN111164807A (en) * 2017-09-29 2020-05-15 Ａｔｔａｃｃａｔｏ合同会社 Binder for lithium ion battery, and electrode and separator using same
CN115320209A (en) * 2022-06-08 2022-11-11 嘉兴瑞冠包装材料有限公司 Swelling adhesive tape and production process thereof

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20040032910A (en) * 2001-08-13 2004-04-17 클로페이 플라스틱 프로덕츠 캄파니, 인코포레이티드 Multilayer microporous films and methods of making
KR20070090852A (en) * 2006-03-03 2007-09-06 주식회사 엘지화학 Electrochemical device with high safety at high temperature
KR20080013209A (en) * 2006-08-07 2008-02-13 한국과학기술연구원 Separator having ultrafine fibrous layer with heat resistance and secondary battery having the same
KR20110129109A (en) * 2010-05-25 2011-12-01 코오롱패션머티리얼 (주) Porous nanofiber web and method for manufacturing the same
KR20120046091A (en) * 2010-11-01 2012-05-09 주식회사 아모그린텍 Electrode assembly, rechargeable battery using the same and method of manufacturing the same

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20040032910A (en) * 2001-08-13 2004-04-17 클로페이 플라스틱 프로덕츠 캄파니, 인코포레이티드 Multilayer microporous films and methods of making
KR20070090852A (en) * 2006-03-03 2007-09-06 주식회사 엘지화학 Electrochemical device with high safety at high temperature
KR20080013209A (en) * 2006-08-07 2008-02-13 한국과학기술연구원 Separator having ultrafine fibrous layer with heat resistance and secondary battery having the same
KR20110129109A (en) * 2010-05-25 2011-12-01 코오롱패션머티리얼 (주) Porous nanofiber web and method for manufacturing the same
KR20120046091A (en) * 2010-11-01 2012-05-09 주식회사 아모그린텍 Electrode assembly, rechargeable battery using the same and method of manufacturing the same

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPWO2016110894A1 (en) * 2015-01-09 2017-10-19 日本ゼオン株式会社 Nonaqueous secondary battery separator, method for producing the same, and nonaqueous secondary battery
CN111164807A (en) * 2017-09-29 2020-05-15 Ａｔｔａｃｃａｔｏ合同会社 Binder for lithium ion battery, and electrode and separator using same
CN111164807B (en) * 2017-09-29 2023-12-01 Ａｔｔａｃｃａｔｏ合同会社 Binder for lithium ion battery, and electrode and separator using same
CN111106381A (en) * 2018-10-25 2020-05-05 深圳市比亚迪锂电池有限公司 Polymer electrolyte, preparation method thereof and lithium ion battery
CN110048158A (en) * 2019-04-25 2019-07-23 北京卫蓝新能源科技有限公司 A kind of in-situ polymerization ELECTRODE WITH BILAYER POLYMERIC object dielectric film and its preparation method and application
CN110048158B (en) * 2019-04-25 2021-09-07 北京卫蓝新能源科技有限公司 In-situ polymerization double-layer polymer electrolyte membrane and preparation method and application thereof
CN115320209A (en) * 2022-06-08 2022-11-11 嘉兴瑞冠包装材料有限公司 Swelling adhesive tape and production process thereof
CN115320209B (en) * 2022-06-08 2023-07-28 嘉兴瑞冠包装材料有限公司 Swelling adhesive tape and production process thereof

Similar Documents

Publication Publication Date Title
WO2012060604A2 (en) Heat-resistant separator, electrode assembly and secondary battery using the same, and method for manufacturing secondary battery
US10135092B2 (en) Polymer electrolyte, lithium secondary battery using same, and method for manufacturing lithium secondary battery
WO2011055967A2 (en) Heat-resistant and high-tenacity ultrafine fibrous separation layer, method for manufacturing same, and secondary cell using same
US9647255B2 (en) Porous separation membrane, secondary battery using same, and method for manufacturing said secondary battery
WO2014030899A1 (en) Composite porous separation membrane having shut-down function, method for manufacturing same, and secondary batteries using same
WO2018034526A1 (en) Anode comprising multiple protective layers, and lithium secondary battery comprising same
WO2013012292A2 (en) Separator, manufacturing method thereof, and electrochemical device employing same
WO2019164130A1 (en) Separator, method for manufacturing same, and lithium battery including same
WO2013115594A1 (en) Electrode assembly, production method for same, and secondary battery using same
WO2013028046A2 (en) Separator having a microcapsule and electrochemical device including same
WO2018084431A1 (en) Electrode, secondary battery using same, and method for manufacturing electrode
WO2011019187A2 (en) Lithium secondary battery
WO2014112776A1 (en) Polymer electrolyte, lithium secondary battery using same, and method for manufacturing lithium secondary battery
WO2018012694A1 (en) Lithium secondary battery having lithium metal formed on cathode and manufacturing method therefor
WO2011115453A2 (en) Ultra-fine fibrous porous separator having shutdown function and method for producing same
WO2020013675A1 (en) Electrochemical element separation membrane including low-resistance coating layer, and method for manufacturing same
WO2014098519A1 (en) Porous separation membrane, secondary battery using same, and method for manufacturing said secondary battery
WO2017135793A1 (en) Cable-type secondary battery and manufacturing method therefor
WO2020022851A1 (en) Separator and electrochemical device comprising same
WO2020013671A1 (en) Separator for electrochemical device, and electrochemical device comprising same
KR20150141403A (en) Complex fibrous separator, manufacturing method thereof and secondary battery using the same
WO2013095038A1 (en) Electrode assembly and method for manufacturing same
KR101976586B1 (en) Complex fibrous separator, manufacturing method thereof and secondary battery using the same
WO2019112353A1 (en) Separator for lithium ion secondary battery, and lithium metal battery comprising same
WO2015065116A1 (en) Organic-inorganic complex porous membrane, separator comprising same, and electrode structure body

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: 13865736

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 13865736

Country of ref document: EP

Kind code of ref document: A1