WO2014112776A1 - Polymer electrolyte, lithium secondary battery using same, and method for manufacturing lithium secondary battery - Google Patents

Polymer electrolyte, lithium secondary battery using same, and method for manufacturing lithium secondary battery Download PDF

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Publication number
WO2014112776A1
WO2014112776A1 PCT/KR2014/000417 KR2014000417W WO2014112776A1 WO 2014112776 A1 WO2014112776 A1 WO 2014112776A1 KR 2014000417 W KR2014000417 W KR 2014000417W WO 2014112776 A1 WO2014112776 A1 WO 2014112776A1
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Prior art keywords
porous
polymer
electrolyte
nanofiber web
gel polymer
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PCT/KR2014/000417
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French (fr)
Korean (ko)
Inventor
최원길
장주희
손용우
노승윤
서인용
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주식회사 아모그린텍
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Priority claimed from KR1020130004590A external-priority patent/KR101639020B1/en
Priority claimed from KR1020130131035A external-priority patent/KR101576151B1/en
Application filed by 주식회사 아모그린텍 filed Critical 주식회사 아모그린텍
Priority to CN201480004790.9A priority Critical patent/CN104919639B/en
Publication of WO2014112776A1 publication Critical patent/WO2014112776A1/en
Priority to US14/797,431 priority patent/US10135092B2/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/431—Inorganic material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0565—Polymeric materials, e.g. gel-type or solid-type
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/431—Inorganic material
    • H01M50/434—Ceramics
    • 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
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • 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
    • 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
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • the present invention relates to a polymer electrolyte, a lithium secondary battery using the same, and a method for manufacturing the same.
  • a gel polymer electrolyte is formed by polymerization of a gel polymer-forming monomer impregnated into a porous nanofiber web, and a porous nanofiber web is used.
  • the present invention relates to a polymer electrolyte capable of preventing a short circuit between the positive electrode and the negative electrode, a lithium secondary battery using the same, and a method of manufacturing the same.
  • 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 Laid-Open Patent Publication No. 10-2006-1743 discloses a lithium secondary battery comprising a positive electrode and a negative electrode capable of reversible intercalation / deintercalation of lithium, and an electrolyte, wherein the electrolyte includes a cyclic carbonate and an alkyl substituent.
  • Eggplant has proposed a lithium secondary battery containing a non-aqueous organic solvent containing a lactone compound, a lithium salt and a gel forming compound.
  • the secondary battery has a structure in which the positive electrode and the negative electrode are separated by a gel electrolyte, ionic conductivity is reduced when the electrolyte is formed into a thick film, and a short circuit occurs between the positive electrode and the negative electrode when formed as a thin film. There is.
  • Korean Laid-Open Patent Publication No. 10-2004-84117 is laminated in the order of an anode, a separator, and then a cathode, and inserted into an aluminum laminate film, and injected with a precursor mixed with a liquid electrolyte, a polymerized polymer, a reactive monomer or a macromonomer, and a polymerization initiator. Thereafter, a method of manufacturing a lithium ion polymer battery, in which a gel polymer electrolyte is prepared by vacuum encapsulation and holding and polymerization in a constant temperature chamber at 60 ° C. to 80 ° C. for up to 1 hour 30 minutes, has been proposed.
  • the manufacturing method of the lithium ion polymer battery is IPN (Interpenetrating Polymer Network), HDDA (Hexanedioldiacrylate) and triethylene glycol using one or two or more acrylate monomers capable of reacting with a polymer having an acrylate group polymerized in a precursor.
  • the physical properties of the gel polymer electrolyte can be changed by adding a reactive modifier using at least one acrylate having two or more reactors such as diethyleneglycoldimehtacrylate and tetraethyleneglycoldiacrylate. It is characterized by changing the.
  • the method of manufacturing the lithium ion polymer battery has a low porosity by using a nonwoven fabric separator made of PE or PP, and has a problem in that ion conductivity is lowered due to a thick coating layer.
  • the inventors formed an electrode assembly using a porous nanofiber web made of nanofibers as an electrolyte matrix, and then injecting an organic electrolyte mixture of a gel polymer forming monomer and a polymerization initiator and inducing an addition polymerization reaction to form a gel polymer.
  • the monomer was found to form a gel polymer electrolyte by rapid polymerization, but the porous nanofiber web was found to maintain the web shape.
  • 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 to form a gel polymer electrolyte by the polymerization reaction of the gel polymer forming monomer impregnated in the porous nanofiber web, and to the porous nanofiber web
  • the present invention provides a polymer electrolyte, a lithium secondary battery using the same, and a method of manufacturing the same, which can prevent a short circuit between the positive electrode and the negative electrode.
  • Another object of the present invention is to provide a polymer electrolyte, a lithium secondary battery using the same, and a method of manufacturing the same, which can ensure fast and uniform impregnation of an organic electrolyte using a porous nanofiber web made of nanofibers as an electrolyte matrix.
  • the present invention provides a polymer electrolyte, a lithium secondary battery using the same, and a method of manufacturing the same, capable of increasing ion conductivity along with thinning.
  • the polymer electrolyte of the present invention comprises a separator consisting of a first porous nanofiber web having a plurality of nanofibers; And a gel polymer part impregnated in the first porous nanofiber web, wherein the gel polymer part is impregnated in the first porous nanofiber web and includes an organic solvent, a solute of lithium salt, a gel polymer forming monomer and a polymerization initiator. It is formed by the polymerization reaction of the said monomer for gel polymer formation in the inside.
  • the lithium secondary battery according to the present invention includes a positive electrode and a negative electrode capable of occluding and releasing lithium, and a polymer electrolyte disposed between the positive electrode and the negative electrode, the polymer electrolyte comprising: a porous separator including a plurality of nanofibers; And a gel polymer part impregnated in the porous separator, wherein the gel polymer part is impregnated in the porous separator and contains the organic solvent, a solute of lithium salt, a monomer for forming a gel polymer and a monomer for forming the gel polymer in an electrolyte including a polymerization initiator. It is characterized by being formed by a polymerization reaction.
  • Method for producing a lithium secondary battery comprises the steps of dissolving a single or mixed polymer in a solvent to form a spinning solution; Spinning the spinning solution to form a porous separator having a plurality of nanofibers; Forming an electrode assembly by inserting the porous separator 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 organic electrolyte including at least a monomer for forming a gel polymer and a polymerization initiator; And performing a gelling heat treatment to polymerize the gel polymer forming monomer to form a gel polymer electrolyte, wherein the porous separator maintains a web shape.
  • a method of manufacturing a lithium secondary battery according to the present invention by using a pair of porous separators each having a plurality of nanofibers, while separating a plurality of unit cathode cells and a plurality of unit anode cells alternately Forming an electrode assembly by laminating; Taping the electrode assembly into a compression band; Embedding the electrode assembly in a case and injecting an organic electrolyte including at least a monomer for forming a gel polymer and a polymerization initiator; And performing a gelling heat treatment to polymerize the gel polymer forming monomer to form a gel polymer electrolyte.
  • a lithium secondary battery according to the present invention is an electrode assembly alternately stacked while separating a plurality of unit cathode cells and a plurality of unit cathode cells using a pair of porous separator; A compression band taping the outer circumference of the electrode assembly; A case having an electrode assembly taped with the compression band; And a polymer electrolyte disposed between the unit anode cell and the unit cathode cell, wherein the polymer electrolyte includes a gel polymer part impregnated in the porous separator and the porous separator, and the gel polymer part is impregnated in the porous separator. It is formed by the polymerization reaction of the said monomer for gel polymer formation in the organic solvent, the solute of a lithium salt, the electrolyte for containing a gel polymer formation monomer, and a polymerization initiator.
  • a porous separator made of one of a porous nanofiber web, a laminate of a porous nanofiber web and an inorganic porous film, a laminate of a porous nanofiber web and a porous nonwoven fabric, and a laminate of a porous nonwoven fabric and an inorganic porous film.
  • an organic electrolyte solution containing a mixture of a gel polymer forming monomer and a polymerization initiator is injected and an addition polymerization reaction is performed to cause the gel polymer forming monomer to polymerize the gel polymer electrolyte by polymerization.
  • the porous nanofiber web maintains the shape of the web as it is, the short circuit between the anode and the cathode can be prevented and safety can be achieved.
  • the porous nanofiber web made of nanofibers is used as the electrolyte matrix, so that the porosity is high, thereby ensuring fast and uniform electrolyte impregnation of the organic electrolyte, and thinning the polymer electrolyte itself, thereby allowing ions between the anode and the cathode.
  • the conductivity can be increased, and the mechanical properties are excellent.
  • a part of the polymer electrolyte is filled in the positive electrode and the negative electrode so that the positive electrode and the negative electrode and the polymer electrolyte are adhered, thereby minimizing the reduction of OCV.
  • the electrode assembly suppresses the shape of expansion and contraction during charging and discharging, thereby preventing the separation between the electrolyte and the electrode, thereby increasing the interfacial resistance. I can suppress it.
  • porous separator in which a thin inorganic porous film or a porous nanofiber web is added to one side of the porous nonwoven fabric used as a support, a decrease in porosity (porosity) can be suppressed to decrease OCV.
  • 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 composite porous separator 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. 8 is a cross-sectional view of a composite porous separator according to a third preferred embodiment of the present invention.
  • FIG. 9 is a cross-sectional view of a composite porous separator according to a fourth preferred embodiment of 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 a porous nanofiber web (electrolyte matrix), which is a porous separator, is assembled into a case together with a positive electrode and a negative electrode, and an organic electrolyte solution in which a gel polymer forming monomer and a polymerization initiator are mixed is injected into a case.
  • an organic electrolyte solution in which a gel polymer forming monomer and a polymerization initiator are mixed is injected into a case.
  • It refers to an inorganic pore type gel polymer electrolyte in which a gel polymer is synthesized by performing a gelation process in a state in which an organic electrolyte solution is embedded in a nanofiber web and then polymerizing a monomer.
  • Figure 1 is a cross-sectional view showing a lithium secondary battery according to a first preferred embodiment of the present invention
  • Figure 2 is a cross-sectional view showing a composite porous separator according to a second preferred embodiment of the present invention.
  • a lithium secondary battery that is, a lithium polymer battery according to a first preferred embodiment of the present invention may be, for example, a positive electrode 1 and a gel polymer electrolyte of an inorganic pore type when forming a full cell. (5) and the cathode (3).
  • 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 includes a porous nanofiber web 15 made of a plurality of nanofibers 150 and an organic electrolyte solution in which a monomer and a polymerization initiator for forming a gel polymer are mixed in the porous nanofiber web 15.
  • the gel polymer unit 17 is composed of a gel polymer in which a gel polymer is synthesized by a polymerization reaction of monomers through a gelation heat treatment step.
  • a porous nanofiber web 15 composed of a single layer is used as the porous separator serving as an electrolyte matrix.
  • the porous nanofiber web 15 may be used as long as it is a polymer capable of dissolving in a solvent to form a spinning solution and then spinning by an electrospinning method to form the nanofibers 150.
  • a single polymer or a mixed polymer can be used.
  • the polymer may be a swellable polymer, a non-swellable polymer, a heat resistant polymer, a mixed polymer in which a swellable polymer and a non-swellable polymer are mixed, or a mixed polymer in which a swellable polymer and a high heat resistant polymer are mixed.
  • the porous nanofiber web 15 forms a spinning solution by dissolving a single or mixed polymer in a solvent to form a spinning solution, and then spins the spinning solution to form a porous nanofiber web made of ultra-fine fibers and calenders at a temperature below the melting point of the polymer. Ring is formed.
  • the porous nanofiber web 15 may include a predetermined amount of inorganic particles in the spinning solution to enhance heat resistance.
  • the swellable polymer and the non-swellable polymer are mixed in a weight ratio in the range of 6: 4 to 1: 9, preferably in a weight ratio in the range of 5: 5 to 3: 7. It is preferable.
  • Non-swellable polymers have a relatively high melting point because of their high molecular weight compared to swellable polymers.
  • 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.
  • the swellable polymers usable in the present invention are resins in which swelling occurs in the electrolyte, and can be formed into ultrafine nanofibers by electrospinning.
  • PVDF polyvinylidene fluoride
  • poly (vinylidene fluoride-co-hexa) Fluoropropylene) perfuluropolymer
  • poly (oxymethylene-oligo- Oxyethylene) polyoxides including polyethylene oxide and polypropylene oxide
  • polyvinylacetate poly (vinylpyrrolidone-vinylacetate)
  • polystyrene and polystyrene acrylonitrile copolymers polyacrylonitrile methyl methacrylate copolymers
  • Polyacrylonitrile containing Trill copolymers polymethylmethacrylates, polymethyl
  • the heat-resistant or non-swellable polymer that can be used in the present invention can be dissolved in an organic solvent for electrospinning, and swelling is slower or swelling than the swelling polymer by an organic solvent included in the organic electrolyte, and the melting point is 180 ° C.
  • polyacrylonitrile PAN
  • polyamide polyimide
  • polyamideimide polyamideimide
  • polysulfone polyetherketone
  • polyethylene terephthalate poly Aromatic polyesters such as trimethylene telephthalate, polyethylene naphthalate and the like
  • polyphosphazenes such as polytetrafluoroethylene
  • polydiphenoxyphosphazene poly ⁇ bis [2- (2-methoxyethoxy) phosphazene] ⁇ Copolymers
  • cellulose acetates cellulose acetates, including polyurethanes and polyetherurethanes Sites butyrate, and the like can be used cellulose acetate propionate.
  • the porous nanofiber web 15 is obtained by spinning a spinning solution in which a swellable polymer alone or a mixed polymer in which a swellable polymer and a heat resistant or non-swellable polymer are mixed is dissolved, and the air electrospinning (AES) shown in FIG. It is desirable to radiate using air-electrospinning equipment.
  • 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 has a thickness of 5 to 50 ⁇ m, preferably 10 to 25 ⁇ m, more preferably 10 to 15 ⁇ m. Do. When the thickness of the porous nanofiber web 15 is less than 5 ⁇ m, not only manufacturing is difficult but also the thickness becomes too thin, and a short may occur. When the thickness exceeds 50 ⁇ m, the thickness of the polymer electrolyte is also increased to increase the ions. The conductivity will drop.
  • the nanofibers 150 forming the porous nanofiber web 15 preferably have a diameter of 50 nm to 2 ⁇ m.
  • the diameter of the nanofibers 150 is less than 50 nm, it is difficult to manufacture, and when the diameter of the nanofibers is greater than 2 ⁇ m, the thickness of the porous nanofiber web 15 also becomes a thick film.
  • the porosity of the porous nanofiber web 15 is set in the range of 60 to 80%, and the Gurley second is preferably 5 to 30 seconds.
  • the inorganic particles contained in the porous nanofiber web 15 in a small amount 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 inorganic particles to be added is preferably contained in the range of 10 to 25% by weight when the size of the inorganic particles is between 10 to 100nm. 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 When the content of the inorganic particles is less than 10% by weight, the film does not maintain the shape, shrinkage occurs, the desired heat resistance characteristics are not obtained, and when it exceeds 25% by weight, the radiation trouble phenomenon that the tip of the spinning nozzle is contaminated occurs. The solvent volatilization is fast and the film strength is lowered.
  • 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 gel polymer portion 17 of the polymer electrolyte 5 is polymerized with the gel polymer forming monomer in a state where the porous nanofiber web 15 is sandwiched between the positive electrode 1 and the negative electrode 3 and integrated into a case. After filling the organic electrolyte solution in which the initiator is mixed, the gel polymer in the gel state is synthesized by the polymerization reaction of the monomer through the gelation heat treatment step.
  • the gel polymer electrolyte of the present invention is formed by polymerizing the above-mentioned monomer for gel polymer formation according to a conventional method.
  • the gel polymer electrolyte may be formed by in-situ polymerization of a monomer for forming a gel polymer in an electrochemical device.
  • In-situ polymerization in the electrochemical device is carried out through thermal polymerization, the polymerization time takes about 20 minutes to 12 hours, the thermal polymerization temperature may be 40 to 90 °C.
  • the organic electrolyte contained in the porous nanofiber web 15 includes a non-aqueous organic solvent and a solute of lithium salt, a monomer for forming a gel polymer, and a polymerization initiator.
  • 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.
  • MMA methyl methacrylate
  • PMMA polymethyl methacrylate
  • the gel polymer forming monomer may be any monomer as long as the polymer forms a gel polymer while the polymerization reaction is carried out by a polymerization initiator.
  • a polymerization initiator for example, polyethylene oxide (PEO), polypropylene oxide (PPO), polyacrylonitrile (PAN), polyvinylidene fluoride (PVDF), polymethacrylate (PMA), polymethyl methacrylate (PMMA)
  • PEO polyethylene oxide
  • PPO polypropylene oxide
  • PAN polyacrylonitrile
  • PVDF polyvinylidene fluoride
  • PMA polymethacrylate
  • PMMA polymethyl methacrylate
  • the polyacrylate which has two or more functional groups such as a monomer with respect to the polymer, polyethyleneglycol dimethacrylate, and polyethyleneglycol acrylate, can be illustrated.
  • the gel polymer forming monomer is preferably used in an amount of 1 to 10% by weight based on the organic electrolyte. If the content of the monomer is less than 1, it is difficult to form a gel electrolyte, and if it exceeds 10% by weight, there is a problem of deterioration of life.
  • the polymerization initiator may be included in 0.01 to 5% by weight based on the monomer.
  • polymerization initiator examples include organic peroxides and hydroperoxides such as Benzoyl peroxide (BPO), Acetyl peroxide, Dilauryl peroxide, Di-tertbutylperoxide, Cumyl hydroperoxide, and Hydrogen peroxide, and 2,2-Azobis (2-cyanobutane), 2 2-Azobis (Methylbutyronitrile), AIBN (Azobis (iso-butyronitrile), AMVN (Azobis)
  • BPO Benzoyl peroxide
  • Acetyl peroxide Dilauryl peroxide
  • Di-tertbutylperoxide Di-tertbutylperoxide
  • Cumyl hydroperoxide Cumyl hydroperoxide
  • Hydrogen peroxide examples include 2,2-Azobis (2-cyanobutane), 2 2-Azobis (Methylbutyronitrile), AIBN (Azobis (iso-butyronitrile
  • the polymerization initiator is decomposed by heat to form radicals, and reacts with the monomer by free radical polymerization to form a gel polymer electrolyte, that is, a gel polymer portion 17.
  • the gel polymer electrolyte forming the gel polymer part 17 is preferably 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. Do.
  • the porous nanofiber web 15 maintains the web shape.
  • the organic electrolyte according to the present invention may optionally contain other well-known additives and the like, in addition to the above components.
  • the present invention as shown in the second embodiment shown in Figure 2, the inorganic porous polymer film 5a of the ultra-thin film laminated on one side or both sides of the inorganic polymer electrolyte type 5 of the first embodiment used as an adhesive layer ) May be included.
  • the structure of the second embodiment is first singulated or mixed by air electrospinning (AES) using, for example, a multi-hole spinning pack in which the spinning nozzles are spaced along the direction of travel of the collector.
  • AES air electrospinning
  • the second porous film of the thin film using the second spinning solution in which the single polymer is dissolved is first porous nano. It is laminated on top of the fibrous web 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.
  • the first and second porous nanofiber webs having a two-layer structure are heat-treated to face each other through an infrared lamp heater set at a temperature slightly lower than the melting point of the second porous nanofiber web. 2
  • the porous nanofiber web is converted to the inorganic porous polymer film 5a to obtain a laminated structure of the first porous nanofiber web 15 and the inorganic porous polymer film 5a.
  • the inorganic porous polymer film 5a is preferably formed into a thin film having a thickness of 2 to 5 ⁇ m, and when the thickness is less than 2 ⁇ m, the function of the adhesive layer is weak. The conductivity becomes low.
  • the gelation heat treatment process is performed. A polymer electrolyte is formed.
  • FIG. 3 is a cross-sectional view showing a manufacturing process of a porous separator used as a matrix of a polymer electrolyte according to the present invention
  • FIG. 4 is a cross-sectional view showing a sealing process of a positive electrode and a porous separator according to the present invention
  • FIG. 5 is according to the present invention.
  • FIG. 6 is a schematic plan view of an electrode assembly assembled according to the present invention.
  • the nanofiber web 15 used as the porous separator as shown in FIG. 3 is manufactured by, for example, air electrospinning (AES).
  • AES air electrospinning
  • the collector 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 a single or mixed polymer spinning solution with sufficient viscosity is radiated using the air spray electrospinning device shown in FIG. 3.
  • Ultrafine nanofibers 150 are spun on 26 to form a porous nanofiber web 15, in which case the spun nanofibers 150 are sprayed by injecting air 24a for each spinning nozzle 24. (26) will not be captured and catches flying.
  • the mixed polymer spinning solution is prepared by adding 40-90 wt% non-swellable polymer material and 10-60 wt% 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 uses the mixing motor 22a using pneumatic pressure as a driving source to prevent phase separation until the heat-resistant polymer material and the swellable polymer material are mixed with a solvent and spinning.
  • Mixing tank (21) with a built-in stirrer 22, and a plurality of spinneret (24) connected to the high-voltage generator is a multi-hole nozzle pack (not shown) arranged in a matrix form.
  • the mixed spinning liquid discharged from the mixing tank 21 to the plurality of spinning nozzles 24 connected through the metering pump and the transfer pipe 23 not shown is passed 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.
  • Porous nanofiber web 15 made of ultrafine nanofibers is an ultra-thin, ultra-light, high surface area ratio to volume, and has a 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.
  • a pressure of 0 to 40 kgf / cm 2 excluding the self-weight pressure of the compression roller
  • the calendering temperature and pressure are as follows:
  • the porous nanofiber web 15 obtained after the above-described calendering process if necessary, preferably has a residual solvent or 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 nanofiber web 15 with the transfer sheet 25a disposed inside.
  • one of the positive electrode 1 and the negative electrode 3 may be encapsulated by an encapsulation process using two porous nanofiber webs 15 as a separator.
  • 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.
  • a plurality of unit anode cells 1a-1d are sequentially encapsulated using a pair of porous nanofiber webs 15a and 15b as separators, but may be encapsulated in another manner. .
  • 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 the heat treatment is performed to induce gelation by a polymerization reaction after injecting the above-described organic electrolyte solution and sealing. (S18, S19).
  • the gelation heat treatment process is injected into the organic electrolyte, and then heated to a condition of 20 minutes to 720 minutes at a temperature of 40 °C to 90 °C and then cooled.
  • porous nanofiber webs 15a and 15b disposed between the anode 1 and the cathode 3 are porous separators having a three-dimensional pore structure, impregnation is made very quickly when the organic electrolyte is injected.
  • the gel polymer forming monomer proceeds rapidly with the polymerization initiator to form a gel polymer, but the porous nanofiber web 15 maintains the web shape.
  • the polymer electrolyte 5 is gelated in a state where the gel polymer forming monomer is impregnated into the pores of the porous nanofiber web 15 to form the gel polymer portion 17, thereby forming a liquid organic solvent as a whole.
  • the porous nanofiber web 15 maintains its shape as a matrix without swelling in the electrolyte while forming a gel electrolyte of an inorganic pore type that is substantially free of residual.
  • the gel polymer portion 17 in the gel state functions as a lithium ion conductor that carries lithium ions that are oxidized or reduced in the negative electrode 3 and the positive electrode 1 during charging and discharging of the battery, and the porous nano
  • the fibrous web 15 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.
  • the interfacial resistance between the electrode and the polymer electrolyte 5 decreases and the polymer electrolyte ( 5) can be thinned.
  • Porous nanofiber web 15 of the present invention by impregnating the injected organic electrolyte quickly and uniformly, the battery characteristics can be uniformly expressed over the entire electrolyte membrane.
  • the present invention is not limited thereto, but the multilayer structure Composite porous separators can be used.
  • 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 organic 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 has a porosity in the range of 70 to 80, the thickness of the porous nonwoven fabric is preferably set to 10 to 40um range.
  • the porous nanofiber web 213 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 impregnated with the organic electrolyte and is composed of an ultra-thin film, and thus does not act as a resistance, and the mobility of lithium ions is increased. Done.
  • 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 is swelled by the electrolyte and conducts lithium ions, but the space between the negative electrode and the separator 201a is performed. Blocking formation can prevent lithium ions from accumulating and depositing into lithium metal. 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 15.
  • the composite porous separators 210 and 210a are applied to a lithium polymer battery including a positive electrode, a gel polymer electrolyte, and a negative electrode.
  • the electrode assembly is encapsulated, and an anode and a cathode are assembled. Then, the electrode assembly is cascaded and an organic electrolyte is injected, followed by gelation heat treatment. The gel polymer electrolyte is formed between the positive electrode and the negative electrode.
  • the electrode assembly After assembling the electrode assembly, it is placed in an aluminum or aluminum alloy can or a similar container, and the opening is closed with a cap assembly, followed by injecting an organic electrolyte solution in which a gel polymer forming monomer and a polymerization initiator are mixed.
  • an organic electrolyte solution in which a gel polymer forming monomer and a polymerization initiator are mixed.
  • the web 213 or the non-porous film 213a is swollen with the electrolyte and gelled.
  • the thickness of the inorganic 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, for example, a PVDF inorganic porous film 213a, the inorganic porous film 213a having excellent adhesion has a surface of a negative electrode. Since it is in close contact with the assembly, it serves to suppress the formation of dendrite.
  • 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, the nanofibers are spun onto paper to form a porous nanofiber web, and the first calendering is performed at about 150 degrees, and the nonwoven fabric and the paper are formed by the second calendering at a temperature lower than the first calendering temperature. When made, it is possible to create a firm bond between fibers, creating a highly porous nanofiber web.
  • the paper absorbs the residual solvent contained in the nanofiber web, thereby preventing 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 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.
  • 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 porous nanofiber web 213 or the inorganic porous film 213a are laminated on both sides of the porous nonwoven fabric 211.
  • a part of the porous nanofiber web 213 or the inorganic porous film 213a laminated on both sides of the porous nonwoven fabric 211 may partially block the pores of the porous nonwoven fabric 211 so as to partially block the pores of the porous nonwoven fabric 211. It is embedded in the role of lowering the porosity of the porous nonwoven fabric 211, and serves as an adhesive layer to increase the adhesion between the composite porous separator (210,210a) and the cathode and anode.
  • the porous nanofiber web 213 of the separator When 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, the porous nanofiber web 213 of the separator Alternatively, the inorganic porous film 213a is preferably assembled so that the negative electrode is adhered to the negative electrode. As a result, dendrite formation can be suppressed on the surface of the negative electrode, thereby improving stability.
  • the present invention forms an electrode assembly using a porous nanofiber web as an electrolyte matrix, and then forms an gel polymer electrolyte by injecting an organic electrolyte mixture of a gel polymer forming monomer and a polymerization initiator and causing an addition polymerization reaction.
  • Porous nanofiber web is a technology related to polymer electrolyte which can improve the safety and thinning at the same time by preventing the short circuit between anode and cathode by maintaining the web shape, and is flexible secondary like lithium polymer battery with polymer electrolyte. It can be applied to a battery.

Abstract

The present invention relates to a polymer electrolyte, a lithium secondary battery using the same, and a method for manufacturing the lithium secondary battery, wherein: an electrode assembly is formed by using a porous nanofiber web as an electrolyte matrix; an organic electrolyte having a mixture of a gel polymer-forming monomer and a polymerization initiator is injected, and a gel polymer electrolyte is formed by polymerization; and the porous nanofiber web is maintained in a web form such that stability can be increased by preventing a short circuit between a cathode and an anode. The polymer electrolyte, according to the present invention, comprises: the porous nanofiber web which is provided with a plurality of nanofibers; and a gel polymer portion which is impregnated into the porous nanofiber web, wherein the gel polymer portion is formed by polymerizing the gel polymer-forming monomer after a non-aqueous organic solvent, a solute of lithium salt, and the organic electrolyte having the gel polymer-forming monomer and the polymerization initiator have been impregnated into the porous nanofiber web.

Description

폴리머 전해질, 이를 이용한 리튬 이차 전지 및 그의 제조방법Polymer electrolyte, lithium secondary battery using same, and method for manufacturing same
본 발명은 폴리머 전해질, 이를 이용한 리튬 이차 전지 및 그의 제조방법에 관한 것으로, 특히 다공성 나노섬유 웹에 함침된 겔 폴리머 형성용 모노머의 중합반응에 의해 겔 폴리머 전해질을 구성하고, 다공성 나노섬유 웹에 의해 양극과 음극 사이의 단락을 방지할 수 있는 폴리머 전해질, 이를 이용한 리튬 이차 전지 및 그의 제조방법에 관한 것이다.The present invention relates to a polymer electrolyte, a lithium secondary battery using the same, and a method for manufacturing the same. Particularly, a gel polymer electrolyte is formed by polymerization of a gel polymer-forming monomer impregnated into a porous nanofiber web, and a porous nanofiber web is used. The present invention relates to a polymer electrolyte capable of preventing a short circuit between the positive electrode and the negative electrode, a lithium secondary battery using the same, and a method of manufacturing the same.
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 공개특허공보 10-2006-1743호에는 리튬의 가역적인 인터칼레이션/디인터칼레이션이 가능한 양극과 음극, 및 전해질을 구비하여 이루어지는 리튬 이차 전지에 있어서, 상기 전해질은 환형 카보네이트와 알킬치환기를 가지는 락톤계 화합물을 포함하는 비수성 유기 용매, 리튬염 및 겔 형성화합물을 포함하는 리튬 이차 전지를 제안하고 있다. Korean Laid-Open Patent Publication No. 10-2006-1743 discloses a lithium secondary battery comprising a positive electrode and a negative electrode capable of reversible intercalation / deintercalation of lithium, and an electrolyte, wherein the electrolyte includes a cyclic carbonate and an alkyl substituent. Eggplant has proposed a lithium secondary battery containing a non-aqueous organic solvent containing a lactone compound, a lithium salt and a gel forming compound.
그러나, 상기 이차 전지는 양극과 음극 사이를 겔형 전해질에 의해 분리하는 구조를 가지고 있어, 전해질을 후막으로 형성하는 경우 이온전도도가 떨어지게 되고, 박막으로 형성하는 경우 양극과 음극 사이에 단락이 발생하는 문제가 있다.However, since the secondary battery has a structure in which the positive electrode and the negative electrode are separated by a gel electrolyte, ionic conductivity is reduced when the electrolyte is formed into a thick film, and a short circuit occurs between the positive electrode and the negative electrode when formed as a thin film. There is.
한국 공개특허공보 10-2004-84117호에는 양극, 분리막, 음극 순으로 적층하여 알루미늄 라미네이트 필름에 삽입하고, 액체 전해액, 중합시킨 고분자, 반응성 모노머 또는 매크로모노머, 중합 개시제 등을 혼합한 전구체를 주입한 후 진공 봉입하고, 60℃~80℃의 항온 챔버에서 최대 1시간 30분 정도까지 유지하여 중합시킴에 의해 겔 폴리머 전해질을 제조한 리튬 이온 폴리머 전지의 제조방법이 제안되어 있다.Korean Laid-Open Patent Publication No. 10-2004-84117 is laminated in the order of an anode, a separator, and then a cathode, and inserted into an aluminum laminate film, and injected with a precursor mixed with a liquid electrolyte, a polymerized polymer, a reactive monomer or a macromonomer, and a polymerization initiator. Thereafter, a method of manufacturing a lithium ion polymer battery, in which a gel polymer electrolyte is prepared by vacuum encapsulation and holding and polymerization in a constant temperature chamber at 60 ° C. to 80 ° C. for up to 1 hour 30 minutes, has been proposed.
상기 리튬 이온 폴리머 전지의 제조방법은 전구체에 중합된 아크릴레이트기를 갖는 고분자와 반응이 가능한 아크릴레이트(acrylate) 모노머를 하나 또는 2개 이상 사용한 IPN(Interpenetrating Polymer Network), HDDA(Hexanedioldiacrylate)와 트리에틸렌글리콜디메타크릴레이트(Triethyleneglycoldimehtacrylate), 테트라에틸렌글리콜디아크릴레이트(Tetraethyleneglycoldiacrylate) 등의 반응기를 2개 이상 갖는 아크릴레이트를 적어도 1개 사용하는 반응성 개질제를 첨가하여, 이들의 조성비를 변화시켜 겔 폴리머 전해질의 물성을 변화시키는 것을 특징으로 하고 있다. The manufacturing method of the lithium ion polymer battery is IPN (Interpenetrating Polymer Network), HDDA (Hexanedioldiacrylate) and triethylene glycol using one or two or more acrylate monomers capable of reacting with a polymer having an acrylate group polymerized in a precursor. The physical properties of the gel polymer electrolyte can be changed by adding a reactive modifier using at least one acrylate having two or more reactors such as diethyleneglycoldimehtacrylate and tetraethyleneglycoldiacrylate. It is characterized by changing the.
상기 리튬 이온 폴리머 전지의 제조방법은 PE 또는 PP로 이루어진 부직포 분리막을 사용함에 따라 기공도가 낮으며, 코팅층의 두께가 두꺼워 이온전도도가 떨어지는 문제가 있다.The method of manufacturing the lithium ion polymer battery has a low porosity by using a nonwoven fabric separator made of PE or PP, and has a problem in that ion conductivity is lowered due to a thick coating layer.
본 발명자는 나노섬유로 이루어진 다공성 나노섬유 웹을 전해질 매트릭스로 사용하여 전극 조립체를 형성한 후, 겔 폴리머 형성용 모노머와 중합 개시제가 혼합된 유기 전해액을 주입하고 부가중합반응을 유도하면, 겔 폴리머 형성용 모노머는 빠른 중합반응에 의해 겔 폴리머 전해질을 형성하나, 다공성 나노섬유 웹은 웹 형상을 그대로 유지하는 것을 발견하였다. 본 발명은 이러한 발견에 기초하여 이루어진 것이다.The inventors formed an electrode assembly using a porous nanofiber web made of nanofibers as an electrolyte matrix, and then injecting an organic electrolyte mixture of a gel polymer forming monomer and a polymerization initiator and inducing an addition polymerization reaction to form a gel polymer. The monomer was found to form a gel polymer electrolyte by rapid polymerization, but the porous nanofiber web was found to maintain the web shape. The present invention has been made based on this finding.
따라서, 본 발명은 상기한 종래기술의 문제점을 해결하고자 제안된 것으로, 그 목적은 다공성 나노섬유 웹에 함침된 겔 폴리머 형성용 모노머의 중합반응에 의해 겔 폴리머 전해질을 구성하고, 다공성 나노섬유 웹에 의해 양극과 음극 사이의 단락을 방지하여 안전성을 도모할 수 있는 폴리머 전해질, 이를 이용한 리튬 이차 전지 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 to form a gel polymer electrolyte by the polymerization reaction of the gel polymer forming monomer impregnated in the porous nanofiber web, and to the porous nanofiber web The present invention provides a polymer electrolyte, a lithium secondary battery using the same, and a method of manufacturing the same, which can prevent a short circuit between the positive electrode and the negative electrode.
본 발명의 다른 목적은 나노섬유로 이루어진 다공성 나노섬유 웹을 전해질 매트릭스로 사용하여 유기 전해액의 빠르고 균일한 함침을 보장할 수 있는 폴리머 전해질, 이를 이용한 리튬 이차 전지 및 그의 제조방법을 제공하는 데 있다.Another object of the present invention is to provide a polymer electrolyte, a lithium secondary battery using the same, and a method of manufacturing the same, which can ensure fast and uniform impregnation of an organic electrolyte using a porous nanofiber web made of nanofibers as an electrolyte matrix.
본 발명의 또 다른 목적은 다공성 전해질 매트릭스에 함침된 겔 폴리머 형성용 모노머는 중합반응에 의해 겔 폴리머 전해질을 형성하여 액상의 전해액이 거의 존재하지 않는 고상의 전해질로 변환되어 누액을 방지함에 따라 안전성과 박막화와 함께 이온 전도도를 높일 수 있는 폴리머 전해질, 이를 이용한 리튬 이차 전지 및 그의 제조방법을 제공하는 데 있다.It is still another object of the present invention to form a gel polymer electrolyte impregnated in a porous electrolyte matrix to form a gel polymer electrolyte by a polymerization reaction so that it is converted into a solid electrolyte having almost no liquid electrolyte, thereby preventing leakage. The present invention provides a polymer electrolyte, a lithium secondary battery using the same, and a method of manufacturing the same, capable of increasing ion conductivity along with thinning.
상기한 목적을 달성하기 위하여, 본 발명의 폴리머 전해질은 다수의 나노섬유를 구비하는 제1다공성 나노섬유 웹으로 이루어진 분리막; 및 상기 제1다공성 나노섬유 웹에 함침된 겔 폴리머부를 포함하며, 상기 겔 폴리머부는 상기 제1다공성 나노섬유 웹에 함침되며 유기용매, 리튬염의 용질, 겔 폴리머 형성용 모노머와 중합 개시제를 포함하는 전해액 중에서 상기 겔 폴리머 형성용 모노머의 중합반응에 의해 형성되는 것을 특징으로 한다.In order to achieve the above object, the polymer electrolyte of the present invention comprises a separator consisting of a first porous nanofiber web having a plurality of nanofibers; And a gel polymer part impregnated in the first porous nanofiber web, wherein the gel polymer part is impregnated in the first porous nanofiber web and includes an organic solvent, a solute of lithium salt, a gel polymer forming monomer and a polymerization initiator. It is formed by the polymerization reaction of the said monomer for gel polymer formation in the inside.
본 발명에 따른 리튬 이차 전지는 리튬의 흡장·방출이 가능한 양극과 음극, 및 상기 양극과 음극 사이에 배치되는 폴리머 전해질을 포함하며, 상기 폴리머 전해질은, 다수의 나노섬유를 구비하는 다공성 분리막; 및 상기 다공성 분리막에 함침된 겔 폴리머부를 포함하며, 상기 겔 폴리머부는 상기 다공성 분리막에 함침되며 유기용매, 리튬염의 용질, 겔 폴리머 형성용 모노머와 중합 개시제를 포함하는 전해액 중에서 상기 겔 폴리머 형성용 모노머의 중합반응에 의해 형성되는 것을 특징으로 한다.The lithium secondary battery according to the present invention includes a positive electrode and a negative electrode capable of occluding and releasing lithium, and a polymer electrolyte disposed between the positive electrode and the negative electrode, the polymer electrolyte comprising: a porous separator including a plurality of nanofibers; And a gel polymer part impregnated in the porous separator, wherein the gel polymer part is impregnated in the porous separator and contains the organic solvent, a solute of lithium salt, a monomer for forming a gel polymer and a monomer for forming the gel polymer in an electrolyte including a polymerization initiator. It is characterized by being formed by a polymerization reaction.
본 발명에 따른 리튬 이차 전지의 제조방법은 단일 또는 혼합 폴리머를 용매에 용해시켜 방사용액을 형성하는 단계; 상기 방사용액을 방사하여 다수의 나노섬유를 구비하는 다공성 분리막을 형성하는 단계; 각각 다수의 단위 전극셀로 이루어지는 양극과 음극 사이에 상기 다공성 분리막을 삽입하여 전극 조립체를 형성하는 단계; 상기 전극 조립체를 케이스에 내장하고 적어도 겔 폴리머 형성용 모노머와 중합 개시제를 포함하는 유기 전해액을 주입하는 단계; 및 겔화 열처리를 실시하여, 상기 겔 폴리머 형성용 모노머를 중합반응시켜 겔 폴리머 전해질을 형성하는 단계를 포함하며, 상기 다공성 분리막은 웹 형상을 유지하는 것을 특징으로 한다. Method for producing a lithium secondary battery according to the present invention comprises the steps of dissolving a single or mixed polymer in a solvent to form a spinning solution; Spinning the spinning solution to form a porous separator having a plurality of nanofibers; Forming an electrode assembly by inserting the porous separator 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 organic electrolyte including at least a monomer for forming a gel polymer and a polymerization initiator; And performing a gelling heat treatment to polymerize the gel polymer forming monomer to form a gel polymer electrolyte, wherein the porous separator maintains a web shape.
본 발명의 다른 특징에 따르면, 본 발명에 따른 리튬 이차 전지의 제조방법은 각각 다수의 나노섬유를 구비하는 한쌍의 다공성 분리막을 사용하여 다수의 단위 양극셀과 다수의 단위 음극셀을 분리하면서 교대로 적층함에 의해 전극 조립체를 형성하는 단계; 상기 전극 조립체를 압박밴드로 테이핑하는 단계; 상기 전극 조립체를 케이스에 내장하고 적어도 겔 폴리머 형성용 모노머와 중합 개시제를 포함하는 유기 전해액을 주입하는 단계; 및 겔화 열처리를 실시하여, 상기 겔 폴리머 형성용 모노머를 중합반응시켜 겔 폴리머 전해질을 형성하는 단계를 포함하는 것을 특징으로 한다.According to another feature of the present invention, a method of manufacturing a lithium secondary battery according to the present invention by using a pair of porous separators each having a plurality of nanofibers, while separating a plurality of unit cathode cells and a plurality of unit anode cells alternately Forming an electrode assembly by laminating; Taping the electrode assembly into a compression band; Embedding the electrode assembly in a case and injecting an organic electrolyte including at least a monomer for forming a gel polymer and a polymerization initiator; And performing a gelling heat treatment to polymerize the gel polymer forming monomer to form a gel polymer electrolyte.
본 발명의 또 다른 특징에 따르면, 본 발명에 따른 리튬 이차 전지는 한쌍의 다공성 분리막을 사용하여 다수의 단위 양극셀과 다수의 단위 음극셀을 분리하면서 교대로 적층된 전극 조립체; 상기 전극 조립체의 외주를 테이핑하는 압박밴드; 상기 압박밴드로 테이핑된 전극 조립체가 내장된 케이스; 및 상기 단위 양극셀과 단위 음극셀 사이에 배치되는 폴리머 전해질을 포함하며, 상기 폴리머 전해질은, 상기 다공성 분리막과 상기 다공성 분리막에 함침된 겔 폴리머부를 포함하며, 상기 겔 폴리머부는 상기 다공성 분리막에 함침되며 유기용매, 리튬염의 용질, 겔 폴리머 형성용 모노머와 중합 개시제를 포함하는 전해액 중에서 상기 겔 폴리머 형성용 모노머의 중합반응에 의해 형성되는 것을 특징으로 한다.According to another feature of the present invention, a lithium secondary battery according to the present invention is an electrode assembly alternately stacked while separating a plurality of unit cathode cells and a plurality of unit cathode cells using a pair of porous separator; A compression band taping the outer circumference of the electrode assembly; A case having an electrode assembly taped with the compression band; And a polymer electrolyte disposed between the unit anode cell and the unit cathode cell, wherein the polymer electrolyte includes a gel polymer part impregnated in the porous separator and the porous separator, and the gel polymer part is impregnated in the porous separator. It is formed by the polymerization reaction of the said monomer for gel polymer formation in the organic solvent, the solute of a lithium salt, the electrolyte for containing a gel polymer formation monomer, and a polymerization initiator.
상기한 바와 같이, 본 발명에서는 다공성 나노섬유 웹, 다공성 나노섬유 웹과 무기공 필름의 적층체, 다공성 나노섬유 웹과 다공성 부직포의 적층체, 다공성 부직포와 무기공 필름의 적층체 중 하나로 이루어진 다공성 분리막을 전해질 매트릭스로 사용하여 전극 조립체를 형성한 후, 겔 폴리머 형성용 모노머와 중합 개시제가 혼합된 유기 전해액을 주입하고 부가중합반응을 일으킴에 의해 겔 폴리머 형성용 모노머는 중합반응에 의해 겔 폴리머 전해질을 형성하나, 다공성 나노섬유 웹은 웹 형상을 그대로 유지함에 따라 양극과 음극 사이의 단락을 방지하여 안전성을 도모할 수 있게 된다.As described above, in the present invention, a porous separator made of one of a porous nanofiber web, a laminate of a porous nanofiber web and an inorganic porous film, a laminate of a porous nanofiber web and a porous nonwoven fabric, and a laminate of a porous nonwoven fabric and an inorganic porous film. Is used as an electrolyte matrix to form an electrode assembly, and then an organic electrolyte solution containing a mixture of a gel polymer forming monomer and a polymerization initiator is injected and an addition polymerization reaction is performed to cause the gel polymer forming monomer to polymerize the gel polymer electrolyte by polymerization. However, as the porous nanofiber web maintains the shape of the web as it is, the short circuit between the anode and the cathode can be prevented and safety can be achieved.
본 발명에서는 나노섬유로 이루어진 다공성 나노섬유 웹을 전해질 매트릭스로 사용하여 기공도가 높기 때문에 유기 전해액의 빠르고 균일한 전해액 함침을 보장할 수 있고, 폴리머 전해질 자체를 얇게 할 수 있어 양극과 음극 사이의 이온 전도도를 높일 수 있으며, 기계적 특성이 우수하게 된다.In the present invention, the porous nanofiber web made of nanofibers is used as the electrolyte matrix, so that the porosity is high, thereby ensuring fast and uniform electrolyte impregnation of the organic electrolyte, and thinning the polymer electrolyte itself, thereby allowing ions between the anode and the cathode. The conductivity can be increased, and the mechanical properties are excellent.
또한, 본 발명에서는 전극과의 접착성이 우수한 폴리머 전해질을 사용함에 따라 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 using a polymer electrolyte having excellent adhesion to the electrode, an increase in interfacial resistance can be suppressed by preventing a separation phenomenon between the electrolyte and the electrode, thereby reducing OCV (Open Circuit Voltage). The reduction can be minimized.
더욱이, 본 발명에서는 폴리머 전해질의 일부가 양극 및 음극에 충전되는 것에 의해 양극 및 음극과 폴리머 전해질이 접착되어, OCV의 감소를 최소화할 수 있다.Furthermore, in the present invention, a part of the polymer electrolyte is filled in the positive electrode and the negative electrode so that the positive electrode and the negative electrode and the polymer electrolyte are adhered, thereby minimizing the reduction of OCV.
본 발명에서는 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 있다.In the present invention, as the outside of the electrode assembly is wound with a non-swellable porous thin film sheet, the electrode assembly suppresses the shape of expansion and contraction during charging and discharging, thereby preventing the separation between the electrolyte and the electrode, thereby increasing the interfacial resistance. I can suppress it.
본 발명에서는 지지체로 사용되는 다공성 부직포의 일측면에 박막의 무기공 필름 또는 다공성 나노섬유 웹을 부가한 다공성 분리막을 사용함에 의해 공극률(기공도)을 낮추어 OCV의 저하현상을 억제할 수 있다.In the present invention, by using a porous separator in which a thin inorganic porous film or a porous nanofiber web is added to one side of the porous nonwoven fabric used as a support, a decrease in porosity (porosity) can be suppressed to decrease OCV.
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 복합 다공성 분리막을 나타내는 단면도,2 is a cross-sectional view showing a composite porous separator 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 발명의 바람직한 제3실시예에 따른 복합 다공성 분리막의 단면도,8 is a cross-sectional view of a composite porous separator according to a third preferred embodiment of the present invention;
도 9는 본 발명의 바람직한 제4실시예에 따른 복합 다공성 분리막의 단면도,9 is a cross-sectional view of a composite porous separator according to a fourth preferred embodiment of the present invention;
도 10은 본 발명에 따른 복합 다공성 분리막을 제조하는 제조공정도,10 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 분리막인 다공성 나노섬유 웹(전해질 매트릭스)을 양극 및 음극과 함께 케이스 내부에 조립하고, 겔 폴리머 형성용 모노머와 중합 개시제가 혼합된 유기 전해액을 케이스에 주입하여 다공성 나노섬유 웹 내에 유기 전해액이 함입된 상태에서 겔화 공정을 실시하여 모노머의 중합반응에 의해 겔 상태의 겔 폴리머가 합성된 무기공 타입의 겔형 폴리머 전해질을 말한다.Hereinafter, in the present specification, the polymer electrolyte is a porous nanofiber web (electrolyte matrix), which is a porous separator, is assembled into a case together with a positive electrode and a negative electrode, and an organic electrolyte solution in which a gel polymer forming monomer and a polymerization initiator are mixed is injected into a case. It refers to an inorganic pore type gel polymer electrolyte in which a gel polymer is synthesized by performing a gelation process in a state in which an organic electrolyte solution is embedded in a nanofiber web and then polymerizing a monomer.
첨부된 도 1은 본 발명의 바람직한 제1실시예에 따른 리튬 이차 전지를 나타내는 단면도, 도 2는 본 발명의 바람직한 제2실시예에 따른 복합 다공성 분리막을 나타내는 단면도이다.1 is a cross-sectional view showing a lithium secondary battery according to a first preferred embodiment of the present invention, Figure 2 is a cross-sectional view showing a composite porous separator 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 예를 들어, 풀셀(full cell)을 형성할 때 양극(1), 무기공 타입의 겔형 폴리머 전해질(5) 및 음극(3)을 구비하여 이루어진다.Referring to FIG. 1, a lithium secondary battery, that is, a lithium polymer battery according to a first preferred embodiment of the present invention may be, for example, a positive electrode 1 and a gel polymer electrolyte of an inorganic pore type when forming a full cell. (5) and the cathode (3).
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, 다수의 나노섬유(150)로 이루어진 다공성 나노섬유 웹(15)과, 상기 다공성 나노섬유 웹(15)에 겔 폴리머 형성용 모노머와 중합 개시제가 혼합된 유기 전해액이 함입되어 겔화 열처리 공정을 거침에 따라 모노머의 중합반응에 의해 겔 상태의 겔 폴리머가 합성되어 이루어지는 겔 폴리머부(17)로 구성되어 있다.The polymer electrolyte 5 includes a porous nanofiber web 15 made of a plurality of nanofibers 150 and an organic electrolyte solution in which a monomer and a polymerization initiator for forming a gel polymer are mixed in the porous nanofiber web 15. The gel polymer unit 17 is composed of a gel polymer in which a gel polymer is synthesized by a polymerization reaction of monomers through a gelation heat treatment step.
제1실시예에서는 전해질 매트릭스 역할을 하는 다공성 분리막으로서 단일층으로 이루어진 다공성 나노섬유 웹(15)을 사용한다. In the first embodiment, a porous nanofiber web 15 composed of a single layer is used as the porous separator serving as an electrolyte matrix.
상기 다공성 나노섬유 웹(15)은 용매에 용해되어 방사용액을 형성한 후 전기방사 방법으로 방사되어 나노섬유(150)를 형성할 수 있는 폴리머라면 어떤 것도 사용 가능하다. 이 경우, 단일 폴리머 또는 혼합 폴리머를 사용할 수 있다. 폴리머는 전해액에 팽윤이 이루어지는 팽윤성 폴리머, 비팽윤성 폴리머, 내열성 폴리머, 팽윤성 폴리머와 비팽윤성 폴리머가 혼합된 혼합 폴리머, 팽윤성 폴리머와 고내열성 폴리머가 혼합된 혼합 폴리머를 사용할 수 있다.The porous nanofiber web 15 may be used as long as it is a polymer capable of dissolving in a solvent to form a spinning solution and then spinning by an electrospinning method to form the nanofibers 150. In this case, a single polymer or a mixed polymer can be used. The polymer may be a swellable polymer, a non-swellable polymer, a heat resistant polymer, a mixed polymer in which a swellable polymer and a non-swellable polymer are mixed, or a mixed polymer in which a swellable polymer and a high heat resistant polymer are mixed.
상기 다공성 나노섬유 웹(15)은 단일 또는 혼합 폴리머를 용매에 용해시켜 방사용액을 형성한 후, 방사용액을 방사하여 초극세 섬유상으로 이루어진 다공성 나노섬유 웹을 형성하고, 고분자의 융점 이하의 온도에서 캘린더링하여 형성된다. The porous nanofiber web 15 forms a spinning solution by dissolving a single or mixed polymer in a solvent to form a spinning solution, and then spins the spinning solution to form a porous nanofiber web made of ultra-fine fibers and calenders at a temperature below the melting point of the polymer. Ring is formed.
이 경우, 상기 다공성 나노섬유 웹(15)은 내열성을 강화하기 위하여 상기 방사용액에 무기물 입자가 소정량 포함될 수 있다.In this case, the porous nanofiber web 15 may include a predetermined amount of inorganic particles in the spinning solution to enhance heat resistance.
또한, 팽윤성 폴리머와 비팽윤성 폴리머의 혼합 폴리머를 사용하는 경우, 팽윤성 폴리머와 비팽윤성 폴리머는 6:4 내지 1:9 범위의 중량비, 바람직하게는 5:5 내지 3:7 범위의 중량비로 혼합되는 것이 바람직하다. 비팽윤성 폴리머는 팽윤성 폴리머와 비교할 때 분자량이 크기 때문에 융점도 상대적으로 높다. 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, when using a mixed polymer of the swellable polymer and the non-swellable polymer, the swellable polymer and the non-swellable polymer are mixed in a weight ratio in the range of 6: 4 to 1: 9, preferably in a weight ratio in the range of 5: 5 to 3: 7. It is preferable. Non-swellable polymers have a relatively high melting point because of their high molecular weight compared to swellable polymers. 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.
본 발명에 사용 가능한 팽윤성 폴리머는 전해액에 팽윤이 일어나는 수지로서 전기 방사법에 의하여 초극세 나노섬유로 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 in which swelling occurs in the electrolyte, and can be formed into ultrafine nanofibers by electrospinning. For example, polyvinylidene fluoride (PVDF), poly (vinylidene fluoride-co-hexa) Fluoropropylene), 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- Oxyethylene), polyoxides including polyethylene oxide and polypropylene oxide, polyvinylacetate, poly (vinylpyrrolidone-vinylacetate), polystyrene and polystyrene acrylonitrile copolymers, polyacrylonitrile methyl methacrylate copolymers Polyacrylonitrile containing Trill copolymers, polymethylmethacrylates, polymethylmethacrylate copolymers, and mixtures thereof.
또한, 본 발명에서 사용 가능한 내열성 또는 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 heat-resistant or non-swellable polymer that can be used in the present invention can be dissolved in an organic solvent for electrospinning, and swelling is slower or swelling than the swelling polymer by an organic solvent included in the organic electrolyte, and the melting point is 180 ° C. As the above resin, for example, polyacrylonitrile (PAN), polyamide, polyimide, polyamideimide, poly (meth-phenylene isophthalamide), polysulfone, polyetherketone, polyethylene terephthalate, poly Aromatic polyesters such as trimethylene telephthalate, polyethylene naphthalate and the like, polyphosphazenes such as polytetrafluoroethylene, polydiphenoxyphosphazene, poly {bis [2- (2-methoxyethoxy) phosphazene]} Copolymers, cellulose acetates, cellulose acetates, including polyurethanes and polyetherurethanes Sites butyrate, and the like can be used cellulose acetate propionate.
한편, 다공성 나노섬유 웹(15)은 팽윤성 폴리머 단독, 또는 팽윤성 폴리머와 내열성 또는 비팽윤성 폴리머가 혼합된 혼합 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 a spinning solution in which a swellable polymer alone or a mixed polymer in which a swellable polymer and a heat resistant or non-swellable polymer are mixed is dissolved, and the air electrospinning (AES) shown in FIG. It is desirable to radiate using air-electrospinning equipment.
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 5 내지 50㎛ 두께로 이루어지며, 바람직하게는 10 내지 25㎛, 보다 바람직하게는 10 내지 15㎛인 것이 적당하다. 다공성 나노섬유 웹(15)의 두께가 5㎛ 미만인 경우, 제조가 어려울 뿐 아니라 두께가 너무 얇아지게 되어 쇼트가 발생될 수 있으며, 두께가 50㎛를 초과하는 경우, 폴리머 전해질의 두께도 증가하여 이온 전도도가 떨어지게 된다.For example, the porous nanofiber web 15 produced by air electrospinning (AES) has a thickness of 5 to 50 μm, preferably 10 to 25 μm, more preferably 10 to 15 μm. Do. When the thickness of the porous nanofiber web 15 is less than 5 μm, not only manufacturing is difficult but also the thickness becomes too thin, and a short may occur. When the thickness exceeds 50 μm, the thickness of the polymer electrolyte is also increased to increase the ions. The conductivity will drop.
상기 다공성 나노섬유 웹(15)을 형성하는 나노섬유(150)는 파이버의 직경이 50nm 내지 2㎛ 범위를 이루는 것이 바람직하다.The nanofibers 150 forming the porous nanofiber web 15 preferably have a diameter of 50 nm to 2 μm.
나노섬유(150)의 직경이 50nm 미만인 경우 제조가 어렵고, 2㎛를 초과하는 경우 다공성 나노섬유 웹(15)의 두께도 후막으로 되는 문제가 발생한다. When the diameter of the nanofibers 150 is less than 50 nm, it is difficult to manufacture, and when the diameter of the nanofibers is greater than 2 μm, the thickness of the porous nanofiber web 15 also becomes a thick film.
다공성 나노섬유 웹(15)의 기공도는 60 내지 80% 범위로 설정되고, 걸리값(Gurley second)이 5 내지 30초인 것이 바람직하다.The porosity of the porous nanofiber web 15 is set in the range of 60 to 80%, and the Gurley second is preferably 5 to 30 seconds.
상기 다공성 나노섬유 웹(15)에 소량 함유되는 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 contained in the porous nanofiber web 15 in a small amount 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.
첨가되는 무기물 입자의 함량은 무기물 입자의 크기가 10 내지 100nm 사이일 때 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.The content of the inorganic particles to be added is preferably contained in the range of 10 to 25% by weight when the size of the inorganic particles is between 10 to 100nm. 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 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.When the content of the inorganic particles is less than 10% by weight, the film does not maintain the shape, shrinkage occurs, the desired heat resistance characteristics are not obtained, and when it exceeds 25% by weight, the radiation trouble phenomenon that the tip of the spinning nozzle is contaminated occurs. The solvent volatilization is fast and the film strength is lowered.
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.
상기 폴리머 전해질(5)의 겔 폴리머부(17)는 다공성 나노섬유 웹(15)을 양극(1)과 음극(3) 사이에 넣고, 일체화하여 케이스에 조립한 상태에서 겔 폴리머 형성용 모노머와 중합 개시제가 혼합된 유기 전해액을 충전한 후, 겔화 열처리 공정을 거침에 따라 모노머의 중합반응에 의해 겔 상태의 겔 폴리머가 합성되어 형성된다.The gel polymer portion 17 of the polymer electrolyte 5 is polymerized with the gel polymer forming monomer in a state where the porous nanofiber web 15 is sandwiched between the positive electrode 1 and the negative electrode 3 and integrated into a case. After filling the organic electrolyte solution in which the initiator is mixed, the gel polymer in the gel state is synthesized by the polymerization reaction of the monomer through the gelation heat treatment step.
즉, 본 발명의 겔 폴리머 전해질은 통상적인 방법에 따라 전술한 겔 폴리머 형성용 모노머를 중합시켜 형성된다. 예를 들면, 겔 폴리머 전해질은 전기화학소자의 내부에서 겔 폴리머 형성용 모노머를 in-situ 중합하여 형성될 수 있다.That is, the gel polymer electrolyte of the present invention is formed by polymerizing the above-mentioned monomer for gel polymer formation according to a conventional method. For example, the gel polymer electrolyte may be formed by in-situ polymerization of a monomer for forming a gel polymer in an electrochemical device.
전기화학소자 내 in-situ 중합 반응은 열 중합을 통해 진행되며, 중합 시간은 대략 20분~12시간 정도 소요되며, 열 중합 온도는 40 내지 90℃가 될 수 있다.In-situ polymerization in the electrochemical device is carried out through thermal polymerization, the polymerization time takes about 20 minutes to 12 hours, the thermal polymerization temperature may be 40 to 90 ℃.
이를 위해 상기 다공성 나노섬유 웹(15)에 함입되는 유기 전해액은 비수성 유기용매와 리튬염의 용질, 겔 폴리머 형성용 모노머와 중합 개시제를 포함한다. To this end, the organic electrolyte contained in the porous nanofiber web 15 includes a non-aqueous organic solvent and a solute of lithium salt, a monomer for forming a gel polymer, and a polymerization initiator.
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 겔 폴리머 형성용 모노머는 예를 들어, 중합 반응에 의해 폴리메틸메타크릴레이트(PMMA)를 형성하는 데 필요한 메틸메타크릴레이트(MMA) 모노머를 사용할 수 있다.As the monomer for forming the gel polymer, for example, a methyl methacrylate (MMA) monomer necessary for forming polymethyl methacrylate (PMMA) by a polymerization reaction may be used.
또한, 상기 겔 폴리머 형성용 모노머는 중합 개시제에 의해 중합 반응이 이루어지면서 중합체가 겔 폴리머를 형성하는 모노머라면 어떤 것도 사용 가능하다. 예를 들어, 폴리에틸렌 옥사이드(PEO), 폴리프로필렌 옥사이드(PPO), 폴리아크릴로니트릴(PAN), 폴리비닐리덴플루오라이드(PVDF), 폴리메타크릴레이트(PMA), 폴리메틸메타크릴레이트(PMMA) 또는 그 중합체에 대한 모노머나, 폴리에틸렌글리콜디메타크릴레이트, 폴리에틸렌글리콜아크릴레이트와 같은 2개 이상의 관능기를 가지는 폴리아크릴레이트를 예시할 수 있다.The gel polymer forming monomer may be any monomer as long as the polymer forms a gel polymer while the polymerization reaction is carried out by a polymerization initiator. For example, polyethylene oxide (PEO), polypropylene oxide (PPO), polyacrylonitrile (PAN), polyvinylidene fluoride (PVDF), polymethacrylate (PMA), polymethyl methacrylate (PMMA) Or the polyacrylate which has two or more functional groups, such as a monomer with respect to the polymer, polyethyleneglycol dimethacrylate, and polyethyleneglycol acrylate, can be illustrated.
상기 겔 폴리머 형성용 모노머는 유기 전해액에 대하여 1 내지 10 중량%의 양으로 사용되는 것이 바람직하다. 상기 모노머의 함량이 1 미만이면 겔형의 전해질이 형성되기 어렵고 10 중량%를 초과하는 경우에는 수명 열화의 문제가 있다.The gel polymer forming monomer is preferably used in an amount of 1 to 10% by weight based on the organic electrolyte. If the content of the monomer is less than 1, it is difficult to form a gel electrolyte, and if it exceeds 10% by weight, there is a problem of deterioration of life.
상기 중합 개시제는 모노머에 대하여 0.01~5 중량%로 포함될 수 있다.The polymerization initiator may be included in 0.01 to 5% by weight based on the monomer.
상기 중합 개시제의 예로는 Benzoyl peroxide(BPO), Acetyl peroxide, Dilauryl peroxide, Di-tertbutylperoxide, Cumyl hydroperoxide, Hydrogen peroxide 등의 유기과산화물류나 히드로과산화물류와, 2,2-Azobis(2-cyanobutane), 2,2-Azobis(Methylbutyronitrile), AIBN(Azobis(iso-butyronitrile), AMVN(AzobisExamples of the polymerization initiator include organic peroxides and hydroperoxides such as Benzoyl peroxide (BPO), Acetyl peroxide, Dilauryl peroxide, Di-tertbutylperoxide, Cumyl hydroperoxide, and Hydrogen peroxide, and 2,2-Azobis (2-cyanobutane), 2 2-Azobis (Methylbutyronitrile), AIBN (Azobis (iso-butyronitrile), AMVN (Azobis)
dimethyl-Valeronitrile) 등의 아조화합물류 등이 있다. 상기 중합 개시제는 열에 의해 분해되어 라디칼을 형성하고, 자유라디칼 중합에 의해 모노머와 반응하여 겔 폴리머 전해질, 즉 겔 폴리머부(17)를 형성한다. azo compounds such as dimethyl-Valeronitrile). The polymerization initiator is decomposed by heat to form radicals, and reacts with the monomer by free radical polymerization to form a gel polymer electrolyte, that is, a gel polymer portion 17.
본 발명에서 겔 폴리머부(17)를 형성하는 겔 폴리머 전해질은 전지의 충전 및 방전시에 음극 및 양극에서 산화 또는 환원되는 리튬 이온을 운반해주는 통로 역할을 해줄 수 있도록 전도성이 우수한 고분자로 이루어지는 것이 바람직하다.In the present invention, the gel polymer electrolyte forming the gel polymer part 17 is preferably 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. Do.
이 경우, 겔 폴리머 형성용 모노머는 중합반응이 빠르게 진행되어 겔형 폴리머를 형성하므로, 다공성 나노섬유 웹(15)은 웹 형상을 유지한다.In this case, since the gel polymer forming monomer proceeds rapidly to form a gel polymer, the porous nanofiber web 15 maintains the web shape.
본 발명에 따른 유기 전해액은 상기 성분들 이외에, 주지된 기타 첨가제 등을 선택적으로 함유할 수 있다.The organic electrolyte according to the present invention may optionally contain other well-known additives and the like, in addition to the above components.
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 필름(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 5a of the ultra-thin film laminated on one side or both sides of the inorganic polymer electrolyte type 5 of the first embodiment used as an adhesive layer ) May be included.
상기 제2실시예의 구조는 예를 들어, 방사노즐이 콜렉터의 진행방향을 따라 간격을 두고 배치된 멀티-홀(multi-hole) 방사팩을 사용하여 에어 전기방사(AES)에 의해 먼저 단일 또는 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. The structure of the second embodiment is first singulated or mixed by air electrospinning (AES) using, for example, a multi-hole spinning pack in which the spinning nozzles are spaced along the direction of travel of the collector. After forming the first porous nanofiber web 15 using the first spinning solution in which the polymer is dissolved, the second porous film of the thin film using the second spinning solution in which the single polymer is dissolved is first porous nano. It is laminated on top of the fibrous web 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 대향하여 통과하도록 열처리하면 제2 다공성 나노섬유 웹은 무기공 폴리머 필름(5a)으로 변환되어 제1 다공성 나노섬유 웹(15)과 무기공 폴리머 필름(5a)의 적층 구조가 얻어진다.Subsequently, in a subsequent step, the first and second porous nanofiber webs having a two-layer structure are heat-treated to face each other through an infrared lamp heater set at a temperature slightly lower than the melting point of the second porous nanofiber web. 2 The porous nanofiber web is converted to the inorganic porous polymer film 5a to obtain a laminated structure of the first porous nanofiber web 15 and the inorganic porous polymer film 5a.
상기 무기공 폴리머 필름(5a)은 2 내지 5㎛ 두께로 박막으로 형성하는 것이 바람직하며, 2㎛ 미만인 경우 접착층으로서의 기능이 약하고, 5㎛를 초과하는 경우 전체적인 폴리머 전해질의 두께가 박막화가 어렵고 동시에 이온 전도도가 낮아지게 된다. The inorganic porous polymer film 5a is preferably formed into a thin film having a thickness of 2 to 5 μm, and when the thickness is less than 2 μm, the function of the adhesive layer is weak. The conductivity becomes low.
상기한 제1 다공성 나노섬유 웹(15)과 무기공 폴리머 필름(5a)이 적층된 복합 다공성 분리막을 사용하여 전극 조립체를 형성하고 전해액을 충전한 후, 겔화 열처리 공정을 진행하면 도 2에 도시된 폴리머 전해질이 형성된다.After forming the electrode assembly and filling the electrolyte using the composite porous separator in which the first porous nanofiber web 15 and the inorganic porous polymer film 5a are stacked, the gelation heat treatment process is performed. A polymer electrolyte is formed.
이하에 도 3 내지 도 6을 참고하여, 본 발명에 따른 리튬 폴리머 이차전지의 제조방법을 설명한다.Hereinafter, a method of manufacturing a lithium polymer secondary battery according to the present invention will be described with reference to FIGS. 3 to 6.
도 3은 본 발명에 따른 폴리머 전해질의 매트릭스로 이용되는 다공성 분리막의 제조공정을 나타내는 공정 단면도, 도 4는 본 발명에 따른 양극과 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 matrix of a polymer electrolyte according to the present invention, FIG. 4 is a cross-sectional view showing a sealing process of a positive electrode and a porous separator according to the present invention, and FIG. 5 is according to the present invention. Schematic cross-sectional view of an assembled electrode assembly, FIG. 6 is a schematic plan view of an electrode assembly assembled according to the present invention.
본 발명에서는 먼저 도 3과 같이 다공성 분리막으로 사용되는 나노섬유 웹(15)을 예를 들어, 에어 전기방사(AES)에 의해 제조한다.In the present invention, first, the nanofiber web 15 used as the porous separator as shown in FIG. 3 is manufactured by, for example, air electrospinning (AES).
즉, 도 3에 나타낸 에어분사 전기방사장치를 사용하여 충분한 점도를 지닌 단일 또는 혼합 폴리머 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 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 a single or mixed polymer spinning solution with sufficient viscosity is radiated using the air spray electrospinning device shown in FIG. 3. Ultrafine nanofibers 150 are spun on 26 to form a porous nanofiber web 15, in which case the spun nanofibers 150 are sprayed by injecting air 24a for each spinning nozzle 24. (26) will not be captured and catches flying.
본 발명에서 혼합 폴리머 방사용액은 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 polymer spinning solution is prepared by adding 40-90 wt% non-swellable polymer material and 10-60 wt% 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 혼합 폴리머를 사용하는 경우 내열성 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 나노섬유(150)로 방출되고, 일정 속도로 이동하는 컨베이어 형태의 접지된 콜렉터(26) 위에 나노섬유(150)가 축적되어 다공성 나노섬유 웹(15)을 형성한다. When using a mixed polymer, the air spray electrospinning apparatus used in the present invention uses the mixing motor 22a using pneumatic pressure as a driving source to prevent phase separation until the heat-resistant polymer material and the swellable polymer material are mixed with a solvent and spinning. Mixing tank (21) with a built-in stirrer 22, and a plurality of spinneret (24) connected to the high-voltage generator is a multi-hole nozzle pack (not shown) arranged in a matrix form. The mixed spinning liquid discharged from the mixing tank 21 to the plurality of spinning nozzles 24 connected through the metering pump and the transfer pipe 23 not shown is passed 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 방사용액을 준비한 후 멀티-홀 노즐팩을 사용하여 에어 전기방사(AES: Air-electrospinning) 방법으로 방사를 진행하면 0.3~1.5um 직경의 초극세 나노섬유(150)의 방사가 이루어지며, 나노섬유의 생성과 동시에 3차원의 네트워크 구조로 융착되어 적층된 형태의 다공성 나노섬유 웹(15)이 트랜스퍼 시트(25a)의 상부에 형성된다. 초극세 나노섬유로 이루어진 다공성 나노섬유 웹(15)은 초박막, 초경량으로서, 부피 대비 표면적 비가 높고, 높은 기공도를 가진다.After preparing the spinning solution as described above using a multi-hole nozzle pack to proceed the spinning by air electrospinning (AES: Air-electrospinning) method of the ultra-fine nanofibers 150 of 0.3 ~ 1.5um diameter is made, Simultaneously with the generation of the nanofibers, porous nanofiber webs 15 fused and stacked in a three-dimensional network structure are formed on the transfer sheet 25a. Porous nanofiber web 15 made of ultrafine nanofibers is an ultra-thin, ultra-light, high surface area ratio to volume, and has a 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 나노섬유 웹(15)의 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, it is possible to maintain the stabilization of the porous nanofiber web 15 in actual use.
내열성 고분자 물질과 팽윤성 고분자 물질이 예를 들어, 각각 PAN과 PVdF 조합인 경우 캘린더링 온도와 압력은 하기와 같다: If the heat-resistant polymer and the swellable polymer 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 나노섬유 웹의 캘린더링 공정이 이루어지면 두께 5 내지 50㎛의 다공성 나노섬유 웹(15)이 얻어지게 된다.When the calendering process of the nanofiber web is made, a porous nanofiber web 15 having a thickness of 5 to 50 μm is obtained.
또한, 본 발명에서는 필요에 따라 상기한 캘린더링 공정이 이루어진 후 얻어진 다공성 나노섬유 웹(15)은 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 나노섬유 웹(15)의 권취롤로서 와인더(31)에 권선된다. In addition, in the present invention, the porous nanofiber web 15 obtained after the above-described calendering process, if necessary, preferably has a residual solvent or a secondary hot air dryer 30 having a temperature of 100 ° C. and a wind speed of 20 m / sec. After the process of removing water, the transfer sheet 25a is wound around the winder 31 as a winding roll of the porous nanofiber web 15 with the transfer sheet 25a disposed inside.
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, 분리막으로서 2장의 다공성 나노섬유 웹(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 nanofiber webs 15 as a separator. 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.
상기 실시예 설명에서는 분리막으로 한쌍의 다공성 나노섬유 웹(15a,15b)을 사용하여 다수의 단위 양극셀(1a-1d)을 순차적으로 봉지화하는 것을 예시하였으나, 다른 방식으로 봉지화하는 것도 가능하다.In the above description of the embodiment, a plurality of unit anode cells 1a-1d are sequentially encapsulated using a pair of porous nanofiber webs 15a and 15b as separators, but may be encapsulated in another manner. .
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), 상기한 유기 전해액을 주입한 후 중합 반응에 의해 겔화가 이루어지도록 열처리를 실시하고 밀봉한다(S18,S19). Subsequently, the electrode assembly 100 taped with the pressing band 101 is embedded in a case (not shown) (S17), and the heat treatment is performed to induce gelation by a polymerization reaction after injecting the above-described organic electrolyte solution and sealing. (S18, S19).
상기 겔화 열처리 공정은 유기 전해액을 주입한 후, 40℃ 내지 90℃ 범위의 온도에서 20분 내지 720분 범위의 조건으로 가열한 후 냉각시킨다.The gelation heat treatment process is injected into the organic electrolyte, and then heated to a condition of 20 minutes to 720 minutes at a temperature of 40 ℃ to 90 ℃ and then cooled.
본 발명에서는 양극(1)과 음극(3) 사이에 배치된 다공성 나노섬유 웹(15a,15b)이 3차원 기공 구조를 갖는 다공성 분리막이므로 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 separators having a three-dimensional pore structure, impregnation is made very quickly when the organic electrolyte is injected.
이 경우, 겔 폴리머 형성용 모노머는 중합 개시제에 의해 중합반응이 빠르게 진행되어 겔형 폴리머를 형성하나, 다공성 나노섬유 웹(15)은 웹 형상을 유지한다.In this case, the gel polymer forming monomer proceeds rapidly with the polymerization initiator to form a gel polymer, but the porous nanofiber web 15 maintains the web shape.
그 결과, 폴리머 전해질(5)은, 겔 폴리머 형성용 모노머가 다공성 나노섬유 웹(15)의 기공에 함침된 상태에서 겔화가 이루어져서 겔 폴리머부(17)를 형성함에 따라 전체적으로는 액상의 유기 용매가 실질적으로 잔류하지 않는 무기공 타입의 겔형 전해질을 형성함과 동시에 다공성 나노섬유 웹(15)은 전해액에 팽윤이 이루어지지 않고 매트릭스로서 형상을 유지한다.As a result, the polymer electrolyte 5 is gelated in a state where the gel polymer forming monomer is impregnated into the pores of the porous nanofiber web 15 to form the gel polymer portion 17, thereby forming a liquid organic solvent as a whole. The porous nanofiber web 15 maintains its shape as a matrix without swelling in the electrolyte while forming a gel electrolyte of an inorganic pore type that is substantially free of residual.
그 결과, 겔 상태의 겔 폴리머부(17)는 전지의 충전 및 방전시에 음극(3) 및 양극(1)에서 산화 또는 환원되는 리튬 이온을 운반해주는 리튬 이온 전도체로서의 기능을 발휘하며, 다공성 나노섬유 웹(15)은 양극(1) 및 음극(3)을 물리적으로 격리하는 분리막으로서 역할을 하여 양극과 음극 사이의 단락을 방지하여 안전성이 향상된다.As a result, the gel polymer portion 17 in the gel state functions as a lithium ion conductor that carries lithium ions that are oxidized or reduced in the negative electrode 3 and the positive electrode 1 during charging and discharging of the battery, and the porous nano The fibrous web 15 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 겔 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, as part of the gel polymer penetrates into the positive electrode 1 and the negative electrode 3 through the gelation process, the interfacial resistance between the electrode and the polymer electrolyte 5 decreases and the polymer electrolyte ( 5) can be thinned.
본 발명의 다공성 나노섬유 웹(15)은, 주입된 유기 전해액을 빠르고 균일하게 함침하여, 전해질 막 전체에 대하여 전지 특성이 균일하게 발현될 수 있다. Porous nanofiber web 15 of the present invention, by impregnating the injected organic electrolyte quickly and uniformly, the battery characteristics can be uniformly expressed over the entire electrolyte membrane.
상기한 실시예 설명에서는 폴리머 전해질(5)을 형성하기 위하여 나노섬유(150)로 이루어진 단일층의 다공성 나노섬유 웹(15)을 분리막으로 사용한 것을 예시하였으나, 본 발명은 이에 제한되지 않고 다층 구조의 복합 다공성 분리막을 사용할 수 있다.In the above description of the embodiment, but using a single layer of the porous nanofiber web 15 made of nanofibers 150 to form a polymer electrolyte (5) as a separator, the present invention is not limited thereto, but the multilayer structure Composite porous separators can be used.
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, 유기 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 organic 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 가지며, 다공성 부직포의 두께는 10 내지 40um 범위로 설정되는 것이 바람직하다.The porous nonwoven fabric 211 has a porosity in the range of 70 to 80, the thickness of the porous nonwoven fabric is preferably set to 10 to 40um range.
상기 다공성 부직포(211)의 일측면에 적층되는 다공성 나노섬유 웹(213)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 213 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 상기 유기 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 impregnated with the organic electrolyte and is composed of an ultra-thin film, and thus does not act as a resistance, and the mobility of lithium ions is increased. Done.
추후 전극 조립시에 상기와 같이 무기공 필름(213a)이 음극 활물질층의 표면에 밀착되도록 압착시키면, 전해액에 의해 팽윤이 이루어지면서 리튬 이온의 전도는 이루어지나, 음극과 분리막(201a) 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 is swelled by the electrolyte and conducts lithium ions, but the space between the negative electrode and the separator 201a is performed. Blocking formation can prevent lithium ions from accumulating and depositing into lithium metal. 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(15)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 15.
상기 복합 다공성 분리막(210,210a)은 양극, 겔형 폴리머 전해질 및 음극을 포함하는 리튬 폴리머 전지에 적용된다.The composite porous separators 210 and 210a are applied to a lithium polymer battery including a positive electrode, a gel polymer electrolyte, and a negative electrode.
상기한 복합 다공성 분리막(210,210a)을 사용하여 도 1 또는 도 5와 같이, 봉지화하고 양극 및 음극이 조립된 전극 조립체를 준비한 후, 전극 조립체를 케이싱하고 유기 전해액을 주입한 후, 겔화 열처리를 실시하면 양극과 음극 사이에 겔형 폴리머 전해질이 형성된다. Using the composite porous membranes 210 and 210a as described above, as shown in FIG. 1 or 5, the electrode assembly is encapsulated, and an anode and a cathode are assembled. Then, the electrode assembly is cascaded and an organic electrolyte is injected, followed by gelation heat treatment. The gel polymer electrolyte is formed between the positive electrode and the negative electrode.
이 경우, 전극 조립체를 조립한 후, 알루미늄 또는 알루미늄 합금 캔 또는 이와 유사한 용기에 넣은 후, 캡조립체로 개구부를 마감한 뒤 겔 폴리머 형성용 모노머와 중합 개시제가 혼합된 유기 전해액을 주입하면 다공성 나노섬유 웹(213) 또는 무기공 필름(213a)은 전해액을 머금고 겔화가 이루어지면서 팽윤된다.In this case, after assembling the electrode assembly, it is placed in an aluminum or aluminum alloy can or a similar container, and the opening is closed with a cap assembly, followed by injecting an organic electrolyte solution in which a gel polymer forming monomer and a polymerization initiator are mixed. The web 213 or the non-porous film 213a is swollen with the electrolyte and gelled.
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 3 내지 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 inorganic 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 예를 들어, 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, for example, a PVDF inorganic porous film 213a, the inorganic porous film 213a having excellent adhesion has a surface of a negative electrode. Since it is in close contact with the assembly, it serves to suppress the formation of dendrite.
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, 나노섬유를 종이에 방사하여 다공성 나노섬유 웹을 형성하고 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, the nanofibers are spun onto paper to form a porous nanofiber web, and the first calendering is performed at about 150 degrees, and the nonwoven fabric and the paper are formed by the second calendering at a temperature lower than the first calendering temperature. When made, it is possible to create a firm 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 잔류 용제(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 residual solvent contained in the nanofiber web, thereby preventing 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 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.
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 다공성 나노섬유 웹(213) 또는 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 porous nanofiber web 213 or the inorganic porous film 213a are laminated on both sides of the porous nonwoven fabric 211.
이 경우, 상기 다공성 부직포(211)의 양측면에 적층되는 다공성 나노섬유 웹(213) 또는 무기공 필름(213a)의 일부는 다공성 부직포(211)의 기공을 부분적으로 차단하도록 다공성 부직포(211)의 표면층에 함입되어 다공성 부직포(211)의 기공도를 낮추는 역할과, 복합 다공성 분리막(210,210a)과 음극 및 양극과의 접착력을 증가시키는 접착층 역할을 한다. In this case, a part of the porous nanofiber web 213 or the inorganic porous film 213a laminated on both sides of the porous nonwoven fabric 211 may partially block the pores of the porous nonwoven fabric 211 so as to partially block the pores of the porous nonwoven fabric 211. It is embedded in the role of lowering the porosity of the porous nonwoven fabric 211, and serves as an adhesive layer to increase the adhesion between the composite porous separator (210,210a) and the cathode and anode.
복합 다공성 분리막(210,210a)이 다공성 부직포(211)의 일측면에 다공성 나노섬유 웹(213) 또는 무기공 필름(213a)이 적층된 2층 구조로 이루어지는 경우, 분리막의 다공성 나노섬유 웹(213) 또는 무기공 필름(213a)이 음극과 접착이 이루어지도록 조립이 이루어지는 것이 바람직하며, 그 결과 음극의 표면에 덴드라이트 형성을 억제할 수 있어 안정성 향상을 도모할 수 있다.When 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, the porous nanofiber web 213 of the separator Alternatively, the inorganic porous film 213a is preferably assembled so that the negative electrode is adhered to the negative electrode. As a result, dendrite formation can be suppressed on the surface of the negative electrode, thereby improving stability.
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 전해질 매트릭스로 사용하여 전극 조립체를 형성한 후, 겔 폴리머 형성용 모노머와 중합 개시제가 혼합된 유기 전해액을 주입하고 부가중합반응을 일으킴에 의해 겔 폴리머 전해질을 형성하고, 다공성 나노섬유 웹은 웹 형상을 그대로 유지함에 따라 양극과 음극 사이의 단락을 방지하여 안전성과 박막화를 동시에 도모할 수 있는 폴리머 전해질에 관한 기술로서, 폴리머 전해질을 구비하는 리튬 폴리머 전지와 같은 플랙시블 이차 전지에 적용될 수 있다.The present invention forms an electrode assembly using a porous nanofiber web as an electrolyte matrix, and then forms an gel polymer electrolyte by injecting an organic electrolyte mixture of a gel polymer forming monomer and a polymerization initiator and causing an addition polymerization reaction. Porous nanofiber web is a technology related to polymer electrolyte which can improve the safety and thinning at the same time by preventing the short circuit between anode and cathode by maintaining the web shape, and is flexible secondary like lithium polymer battery with polymer electrolyte. It can be applied to a battery.

Claims (20)

  1. 다수의 나노섬유를 구비하는 제1다공성 나노섬유 웹으로 이루어진 분리막; 및Separation membrane consisting of a first porous nanofiber web having a plurality of nanofibers; And
    상기 제1다공성 나노섬유 웹에 함침된 겔 폴리머부를 포함하며,It comprises a gel polymer portion impregnated in the first porous nanofiber web,
    상기 겔 폴리머부는 상기 제1다공성 나노섬유 웹에 함침되며 유기용매, 리튬염의 용질, 겔 폴리머 형성용 모노머와 중합 개시제를 포함하는 전해액 중에서 상기 겔 폴리머 형성용 모노머의 중합반응에 의해 형성되는 것을 특징으로 하는 폴리머 전해질. The gel polymer portion is impregnated in the first porous nanofiber web and formed by a polymerization reaction of the monomer for gel polymer formation in an electrolyte containing an organic solvent, a solute of lithium salt, a monomer for gel polymer formation and a polymerization initiator. Polymer electrolyte.
  2. 제1항에 있어서, 상기 겔 폴리머 형성용 모노머는 MMA(메틸메타크릴레이트)이고, 상기 겔 폴리머 전해질은 PMMA(폴리메틸메타크릴레이트)인 것을 특징으로 하는 폴리머 전해질. The polymer electrolyte of Claim 1, wherein the gel polymer forming monomer is MMA (methyl methacrylate), and the gel polymer electrolyte is PMMA (polymethyl methacrylate).
  3. 제1항에 있어서, The method of claim 1,
    상기 겔 폴리머 형성용 모노머의 일부는 중합반응에 의해 겔화가 이루어짐에 따라 양측면에 배치된 양극 및 음극의 내부로 침투가 이루어지는 것을 특징으로 하는 폴리머 전해질. Part of the gel polymer-forming monomer is a polymer electrolyte characterized in that the penetration into the inside of the positive electrode and the negative electrode disposed on both sides as the gelation by the polymerization reaction.
  4. 제1항에 있어서, 상기 제1다공성 나노섬유 웹은 단일 폴리머 또는 혼합 폴리머 방사용액을 방사하여 얻어지는 것을 특징으로 하는 폴리머 전해질. The polymer electrolyte of claim 1, wherein the first porous nanofiber web is obtained by spinning a single polymer or a mixed polymer spinning solution.
  5. 제4항에 있어서, 상기 혼합 폴리머는 팽윤성 폴리머와 비팽윤성 폴리머 조합 또는 팽윤성 폴리머와 내열성 폴리머 조합으로 이루어지는 특징으로 하는 폴리머 전해질. The polymer electrolyte according to claim 4, wherein the mixed polymer comprises a swellable polymer and a non-swellable polymer combination or a swellable polymer and a heat resistant polymer combination.
  6. 제1항에 있어서, 상기 제1다공성 나노섬유 웹은 전해액에 팽윤이 이루어지며 전해질 이온의 전도가 가능한 고분자로 이루어지는 것을 특징으로 하는 폴리머 전해질.The polymer electrolyte of claim 1, wherein the first porous nanofiber web is made of a polymer that swells in an electrolyte and is capable of conducting electrolyte ions.
  7. 제6항에 있어서, 상기 고분자는 CTFE(Chlorotrifluoroethylene)계 PVDF 공중합물 또는 HFP(hexafluoropropylene)계 PVDF 공중합물인 것을 특징으로 하는 폴리머 전해질. The polymer electrolyte of claim 6, wherein the polymer is a chlorofluorofluoro-based PVDF copolymer or a hexafluoropropylene-based PVDF copolymer.
  8. 제1항에 있어서, 상기 제1다공성 나노섬유 웹의 일 측면에 적층되며, 상기 전해액에 팽윤이 이루어지고 전극과의 접착력이 우수한 폴리머로 이루어지며, 기공이 없는 무기공 고분자 필름층을 더 포함하는 것을 특징으로 하는 폴리머 전해질. According to claim 1, It is laminated on one side of the first porous nanofiber web, made of a polymer swelling in the electrolyte and excellent adhesion to the electrode, further comprising an inorganic porous polymer film layer without pores A polymer electrolyte, characterized in that.
  9. 제8항에 있어서, 상기 제1다공성 나노섬유 웹의 두께는 5~50㎛ 범위로 설정되고, 상기 무기공 고분자 필름층의 두께는 2~5㎛ 범위로 설정되는 것을 특징으로 하는 폴리머 전해질. The polymer electrolyte of claim 8, wherein a thickness of the first porous nanofiber web is set in a range of 5 to 50 μm, and a thickness of the inorganic porous polymer film layer is set in a range of 2 to 5 μm.
  10. 제1항에 있어서, 상기 분리막은 The method of claim 1, wherein the separation membrane
    상기 제1다공성 나노섬유 웹의 일 측면에 적층되어, 지지체 역할을 하며 미세기공을 갖는 다공성 부직포; 및 A porous nonwoven fabric laminated on one side of the first porous nanofiber web, serving as a support, and having micropores; And
    상기 제1다공성 나노섬유 웹이 적층된 다공성 부직포의 이면에 제1다공성 나노섬유 웹과 동일한 구조를 갖고 적층되는 제2다공성 나노섬유 웹을 더 포함하며, Further comprising a second porous nanofiber web laminated on the back surface of the porous nonwoven fabric in which the first porous nanofiber web is laminated with the same structure as the first porous nanofiber web,
    상기 제1 및 제2 다공성 나노섬유 웹의 일부는 다공성 부직포의 기공을 부분적으로 차단하도록 다공성 부직포의 표면층에 함입되어 다공성 부직포의 기공도를 낮추는 것을 특징으로 하는 폴리머 전해질.A portion of the first and second porous nanofiber web is embedded in the surface layer of the porous nonwoven fabric to partially block the pores of the porous nonwoven fabric to lower the porosity of the porous nonwoven fabric.
  11. 리튬의 흡장·방출이 가능한 양극과 음극, 및 상기 양극과 음극 사이에 배치되는 폴리머 전해질을 포함하며,A positive electrode and a negative electrode capable of occluding and releasing lithium, and a polymer electrolyte disposed between the positive electrode and the negative electrode,
    상기 폴리머 전해질은, The polymer electrolyte,
    다수의 나노섬유를 구비하는 다공성 분리막; 및A porous separator having a plurality of nanofibers; And
    상기 다공성 분리막에 함침된 겔 폴리머부를 포함하며,It includes a gel polymer portion impregnated in the porous separator,
    상기 겔 폴리머부는 상기 다공성 분리막에 함침되며 유기용매, 리튬염의 용질, 겔 폴리머 형성용 모노머와 중합 개시제를 포함하는 전해액 중에서 상기 겔 폴리머 형성용 모노머의 중합반응에 의해 형성되는 것을 특징으로 하는 리튬 이차 전지.The gel polymer part is impregnated in the porous separator and formed by a polymerization reaction of the gel polymer forming monomer in an electrolyte solution containing an organic solvent, a solute of lithium salt, a monomer for forming a gel polymer and a polymerization initiator. .
  12. 제11항에 있어서, 상기 다공성 분리막은, The method of claim 11, wherein the porous separator,
    지지체 역할을 하며 미세기공을 갖는 다공성 부직포; 및A porous nonwoven fabric serving as a support and having micropores; And
    상기 다공성 부직포의 일측면 또는 양측면에 적층되며, 전기방사된 다수의 나노섬유를 구비하는 다공성 나노섬유 웹을 포함하는 것을 특징으로 하는 리튬 이차 전지.A lithium secondary battery comprising a porous nanofiber web stacked on one side or both sides of the porous nonwoven fabric and having a plurality of electrospun nanofibers.
  13. 제11항에 있어서, 상기 겔 폴리머 형성용 모노머는 MMA(메틸메타크릴레이트)이고, 상기 겔 폴리머 전해질은 PMMA(폴리메틸메타크릴레이트)인 것을 특징으로 하는 리튬 이차 전지.The lithium secondary battery according to claim 11, wherein the gel polymer forming monomer is MMA (methyl methacrylate), and the gel polymer electrolyte is PMMA (polymethyl methacrylate).
  14. 제13항에 있어서, 상기 나노섬유의 직경은 50nm 내지 2㎛ 범위로 설정되고, 상기 다공성 나노섬유 웹의 두께는 5~50㎛ 범위로 설정되는 것을 특징으로 하는 리튬 이차 전지.The lithium secondary battery of claim 13, wherein the diameter of the nanofibers is set in a range of 50 nm to 2 μm, and the thickness of the porous nanofiber web is set in a range of 5 to 50 μm.
  15. 한쌍의 다공성 분리막을 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 using a pair of porous separators;
    상기 전극 조립체의 외주를 테이핑하는 압박밴드; A compression band taping the outer circumference of the electrode assembly;
    상기 압박밴드로 테이핑된 전극 조립체가 내장된 케이스; 및A case having an electrode assembly taped with the compression band; And
    상기 단위 양극셀과 단위 음극셀 사이에 배치되는 폴리머 전해질을 포함하며,It includes a polymer electrolyte disposed between the unit anode cell and the unit cathode cell,
    상기 폴리머 전해질은, 상기 다공성 분리막과 상기 다공성 분리막에 함침된 겔 폴리머부를 포함하며, The polymer electrolyte may include a gel polymer part impregnated in the porous separator and the porous separator,
    상기 겔 폴리머부는 상기 다공성 분리막에 함침되며 유기용매, 리튬염의 용질, 겔 폴리머 형성용 모노머와 중합 개시제를 포함하는 전해액 중에서 상기 겔 폴리머 형성용 모노머의 중합반응에 의해 형성되는 것을 특징으로 하는 리튬 이차 전지.The gel polymer part is impregnated in the porous separator and formed by a polymerization reaction of the gel polymer forming monomer in an electrolyte solution containing an organic solvent, a solute of lithium salt, a monomer for forming a gel polymer and a polymerization initiator. .
  16. 단일 또는 혼합 폴리머를 용매에 용해시켜 방사용액을 형성하는 단계; Dissolving a single or mixed polymer in a solvent to form a spinning solution;
    상기 방사용액을 방사하여 다수의 나노섬유를 구비하는 다공성 분리막을 형성하는 단계; Spinning the spinning solution to form a porous separator having a plurality of nanofibers;
    각각 다수의 단위 전극셀로 이루어지는 양극과 음극 사이에 상기 다공성 분리막을 삽입하여 전극 조립체를 형성하는 단계;Forming an electrode assembly by inserting the porous separator between an anode and a cathode each consisting of a plurality of unit electrode cells;
    상기 전극 조립체를 케이스에 내장하고 적어도 겔 폴리머 형성용 모노머와 중합 개시제를 포함하는 유기 전해액을 주입하는 단계; 및 Embedding the electrode assembly in a case and injecting an organic electrolyte including at least a monomer for forming a gel polymer and a polymerization initiator; And
    겔화 열처리를 실시하여, 상기 겔 폴리머 형성용 모노머를 중합반응시켜 겔 폴리머 전해질을 형성하는 단계를 포함하며,Performing a gelling heat treatment to polymerize the gel polymer forming monomer to form a gel polymer electrolyte,
    상기 다공성 분리막은 웹 형상을 유지하는 것을 특징으로 하는 리튬 이차 전지의 제조방법.The porous separator is a method of manufacturing a lithium secondary battery, characterized in that to maintain the web shape.
  17. 제16항에 있어서, 상기 겔 폴리머 형성용 모노머는 MMA(메틸메타크릴레이트)이고, 상기 겔 폴리머 전해질은 PMMA(폴리메틸메타크릴레이트)인 것을 특징으로 하는 리튬 이차 전지의 제조방법.The method of claim 16, wherein the gel polymer forming monomer is MMA (methyl methacrylate), and the gel polymer electrolyte is PMMA (polymethyl methacrylate).
  18. 제16항에 있어서, 상기 겔화 열처리 단계는 40℃ 내지 90℃ 범위의 온도에서 20분 내지 720분 범위로 이루어지는 것을 특징으로 하는 리튬 이차 전지의 제조방법.The method of claim 16, wherein the gelling heat treatment is performed at a temperature in a range of 40 ° C. to 90 ° C. for 20 minutes to 720 minutes.
  19. 제16항에 있어서, 상기 전극 조립체를 형성하는 단계는 The method of claim 16, wherein forming the electrode assembly
    상기 양극과 음극 중 어느 하나의 스트립형 전극 집전체의 적어도 일면에 전극 활물질층을 코팅하여 전극 스트립을 형성하는 단계; Forming an electrode strip by coating an electrode active material layer on at least one surface of the strip-shaped electrode current collector of any one of the positive electrode and the negative electrode;
    상기 전극 스트립을 스탭-바이-스탭 방식으로 이송하면서 순차적인 블랭킹(blanking)을 실시하여 전극 스트립으로부터 다수의 제1단위 전극셀을 부분적으로 분리 형성하는 단계; Performing sequential blanking while transferring the electrode strip in a step-by-step manner to partially form a plurality of first unit electrode cells from the electrode strip;
    상기 다수의 제1단위 전극셀을 연속적으로 이송하면서 양면에 한쌍의 다공성 분리막으로 봉지하는 단계; 및Encapsulating the pair of porous separators on both sides while continuously transporting the plurality of first unit electrode cells; And
    상기 봉지된 다수의 제1단위 전극셀 사이에 상기 양극과 음극 중 다른 하나의 다수의 제2단위 전극셀을 각각 삽입하여 적층하는 단계를 포함하는 것을 특징으로 하는 리튬 이차 전지의 제조방법.And inserting and stacking a plurality of second unit electrode cells of one of the positive electrode and the negative electrode between the encapsulated plurality of first unit electrode cells, respectively.
  20. 각각 다수의 나노섬유를 구비하는 한쌍의 다공성 분리막을 사용하여 다수의 단위 양극셀과 다수의 단위 음극셀을 분리하면서 교대로 적층함에 의해 전극 조립체를 형성하는 단계;Forming an electrode assembly by alternately stacking a plurality of unit anode cells and a plurality of unit cathode cells using a pair of porous separators each having a plurality of nanofibers;
    상기 전극 조립체를 압박밴드로 테이핑하는 단계; Taping the electrode assembly into a compression band;
    상기 전극 조립체를 케이스에 내장하고 적어도 겔 폴리머 형성용 모노머와 중합 개시제를 포함하는 유기 전해액을 주입하는 단계; 및 Embedding the electrode assembly in a case and injecting an organic electrolyte including at least a monomer for forming a gel polymer and a polymerization initiator; And
    겔화 열처리를 실시하여, 상기 겔 폴리머 형성용 모노머를 중합반응시켜 겔 폴리머 전해질을 형성하는 단계를 포함하는 것을 특징으로 하는 리튬 이차 전지의 제조방법.And performing a gelation heat treatment to polymerize the gel polymer forming monomer to form a gel polymer electrolyte.
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