WO2015020338A1

WO2015020338A1 - Flexible current collector, method for manufacturing same, and secondary battery using same

Info

Publication number: WO2015020338A1
Application number: PCT/KR2014/006801
Authority: WO
Inventors: 최원길; 노승윤
Original assignee: 주식회사 아모그린텍
Priority date: 2013-08-05
Filing date: 2014-07-25
Publication date: 2015-02-12

Abstract

The present invention relates to a flexible current collector which has excellent electrical conductivity while being sufficiently flexible so as to be used in an electrode for a flexible battery, a method for manufacturing the same, and a secondary battery using the same. The flexible current collector of the present invention comprises: a conductive support formed by injecting metal powder into a porous substrate; and a conductive metal layer formed on at least one side of the conductive support.

Description

Flexible current collector and its manufacturing method and secondary battery using the same

The present invention relates to a flexible current collector, a method for manufacturing the same, and a secondary battery using the same, and more particularly, to a flexible current collector, a method for manufacturing the same, and a secondary battery using the same, which have excellent flexibility and excellent electrical conductivity so as to be used for an electrode for flexible batteries. will be.

As consumer demands change due to the digitization and high performance of electronic products, the market demand is shifting to the development of batteries having thin capacity, light weight, and high capacity due to high energy density. In addition, in order to cope with future energy and environmental problems, development of hybrid electric vehicles, electric vehicles, and fuel cell vehicles has been actively progressed, and thus an increase in size of batteries for automotive power supplies is required.

A secondary battery including a high energy density and large capacity lithium ion secondary battery, a lithium ion polymer battery, and a super capacitor (electric double layer capacitor and pseudo capacitor) includes a pair of electrodes, a separator and an electrolyte, or Contains an electrolyte.

Pseudo capacitors use metal oxides as electrode active materials, and electric double layer capacitors use porous carbon materials with high electrical conductivity, thermal conductivity, low density, suitable corrosion resistance, low thermal expansion rate, and high purity as electrode active materials. .

In the capacitor, the electrode is used as a current collector, an expanded foil, a punched foil, or a non-porous foil, which is a two-dimensional structure, specifically, an aluminum or titanium sheet, an expanded aluminum or titanium sheet The whole is used, and various types of current collectors, such as perforated aluminum or titanium thin plate, are used.

These current collectors are two-dimensional current collectors, and in order to increase the binding force between the electrode active material and the current collector, a large amount of binder must be used in the manufacture of the electrode, or the surface of the current collector must be modified, and the electrode active material can be thickened. There are no drawbacks. As a result, the utilization rate and cycle life of the electrode active material are revealed, and the high rate charge and discharge characteristics are somewhat low, and improvement is needed.

Korean Patent No. 10-0567393 (Patent Document 1) discloses a foamed metal, a metal fiber, a porous metal, an etched metal, back and forth in consideration of the above problems. An electrode and a capacitor using a porous three-dimensional current collector such as an uneven metal are proposed.

The material of the porous three-dimensional current collector in the patent document 1 is nickel (Ni), copper (Cu), stainless steel (SUS), titanium (Ti), chromium (Cr), manganese (Mn), iron (Fe), cobalt Metals such as (Co), zinc (Zn), molybdenum (Mo), tungsten (W), silver (Ag), gold (Au), and aluminum (Al) are used.

In the case of a lithium secondary battery, a battery using a carbon-based material as a negative electrode and using LiCoO ₂ or LiMn ₂ O ₄ as a positive electrode has been commercialized. However, in order to increase the performance of the battery, the production of a new electrode active material, the surface modification of the electrode active material, the performance improvement of the membrane and polymer electrolyte, the organic solvent electrolyte to increase the utilization and cycle life of the electrode active material, and to improve the high rate charge and discharge characteristics Much research has been done on the improvement of the performance.

In the case of a commercially available lithium ion battery, a copper thin current collector is used for the negative electrode and an aluminum thin current collector for the positive electrode, and an expanded copper foil or a punched copper foil is used for the negative electrode for a lithium ion polymer battery. The current collector in the form of), the current collector in the form of expanded aluminum foil (punched aluminum foil) or expanded aluminum foil (punched aluminum foil) is used for the positive electrode.

These current collectors are two-dimensional current collectors, and in order to increase the bonding strength between the electrode active material and the current collector, a large amount of binders are used in manufacturing the electrode, the surface of the current collector must be modified, or the electrode active material can not be thickened. have. As a result, the utilization rate and cycle life of the electrode active material are revealed, and the high rate charge / discharge characteristics are somewhat low, and improvement thereof is necessary.

Korean Patent No. 10-0559364 (Patent Document 2), in consideration of the above-mentioned problem, as in Patent Registration No. 10-0567393, foamed metal (metal), metal fiber (metal fiber), porous metal (porous metal) , An electrode composed of a porous three-dimensional current collector, such as an etched metal and a metal unevenly rolled back and forth, a lithium battery using the same, and a method of manufacturing the same.

However, although the porous three-dimensional current collector made of a metal in the above-mentioned Patent Document 2 has a pore size of 1 μm to 10 mm, foamed metal and metal fiber having a uniform pore size are used. , Porous metal, etched metal, and uneven metal back and forth are not easy to manufacture because the material is made of a metallic material.

In particular, in the case of the foamed metal or the porous metal, the open cell type porous three-dimensional structure is low in mass productivity, high in manufacturing cost, difficult to form into a thin plate shape, and effectively increases the specific surface area to volume. There is a limit.

Moreover, since the porous three-dimensional current collector of the said patent document 2 consists of a metal material, it does not have optimal conditions as an electrical power collector in the flexible battery which is thin and requires flexibility.

Accordingly, the present invention has been made in view of the problems of the prior art, the object of which is that the metal powder is injected into the micropores and fixed to a porous substrate such as a porous nanofiber web or nonwoven fabric having a micropores by spinning a polymer material Accordingly, there is provided a flexible current collector having excellent flexibility and electrical conductivity, a method of manufacturing the same, and a secondary battery using the same.

Another object of the present invention is to provide a flexible current collector having excellent flexibility and electrical conductivity and a manufacturing method thereof by injecting metal powder into the micropores of the porous substrate and forming a conductive film on the outer surface thereof.

In order to achieve the above objects, the flexible current collector according to the first aspect of the present invention comprises a conductive support formed by injecting a metal powder into the porous substrate; And a conductive metal layer formed on at least one side of the conductive support.

The flexible current collector of the present invention preferably further includes a conductive adhesive layer interposed between the conductive support and the conductive metal layer.

Preferably, the conductive metal layer and the conductive adhesive layer are made of the same metal, and the metal may be Cu or Al.

The porous substrate may use one of a nanofiber web, a nonwoven fabric, and a laminated structure of the nanofiber web and a nonwoven fabric.

Further, the fiber diameter of the porous substrate is 0.3 to 1.5um, the thickness of the porous substrate may be set to 10 to 70um, preferably 20 to 25um.

In addition, the pore size of the porous substrate is preferably set to several tens of um, the porosity is preferably set to 50 to 90%.

The conductive metal layer is set to 1 to 5um, preferably formed by a plating method.

A secondary battery according to a second aspect of the present invention is a secondary battery including a positive electrode, a negative electrode, a separator interposed between the positive electrode and the negative electrode and an electrolyte, wherein the positive electrode is one or both surfaces of the first current collector and the first current collector And a negative electrode active material formed on the second current collector, and a negative electrode active material formed on one or both surfaces of the second current collector, and the first and second current collectors are each the flexible current collector. It is done.

The electrolyte is composed of a non-aqueous organic solvent, a solute of lithium salt, an organic electrolyte containing a gel polymer forming monomer and a polymerization initiator, and the electrolyte is impregnated in the porous separator and then polymerized with the gel polymer forming monomer. The gel polymer electrolyte can be formed accordingly.

In addition, the electrolyte may be composed of an organic electrolyte containing a non-aqueous organic solvent and a solute of a lithium salt.

Further, the first current collector may include an aluminum (Al) metal layer formed by a plating method, and the second current collector may include a copper (Cu) metal layer formed by a plating method.

The separator is a porous nonwoven fabric serving as a support; And a porous polymer web layer or an inorganic porous polymer film layer laminated on one side of the porous nonwoven fabric and serving as an adhesive layer and an ion moisture storage layer when in close contact with an opposite electrode. Part of the layer is preferably embedded in the surface layer of the porous nonwoven fabric to block the pores of the surface laminated with the porous nonwoven fabric to lower the porosity of the porous nonwoven fabric.

In addition, the separator serves as a support and a porous nonwoven fabric having a first melting point and a first porosity; A first porous polymer web layer laminated on one side of the porous nonwoven fabric and serving as an adhesive layer when in close contact with an opposite electrode; And a second porous polymer web layer laminated on the other side of the porous nonwoven fabric and composed of nanofibers of a heat resistant polymer, wherein the first porous polymer web layer and the second porous polymer web layer each have a first melting point of the porous substrate. It is desirable to have a higher melting point and a porosity equal or similar to the first porosity.

Method for manufacturing a flexible current collector according to a third aspect of the present invention comprises the steps of forming a conductive support by injecting a slurry mixed with a metal powder and a binder in the fine pores of the porous substrate; And forming a conductive metal layer on at least one side of the conductive support.

The method of manufacturing the flexible current collector of the present invention preferably further includes forming a conductive adhesive layer on the conductive support with the same material as the conductive metal layer before forming the conductive metal layer.

As described above, in the present invention, as the metal powder is injected into the micropores and fixed to the porous substrate such as the porous nanofiber web or the nonwoven fabric having the micropores by spinning the polymer material, the flexible current collector having excellent flexibility and electrical conductivity is obtained. to provide.

In addition, in the present invention, a metal powder is injected into the micropores of the porous substrate used as the support, and a conductive film is formed on the outer surface, thereby implementing a flexible electrode using a flexible current collector having excellent flexibility and electrical conductivity. Moreover, the flexible battery can be easily implemented using the flexible electrode.

1 to 4 is a cross-sectional view showing a manufacturing process of a flexible current collector according to a preferred embodiment of the present invention,

5 is a schematic cross-sectional view showing a secondary battery constructed using a flexible current collector according to the present invention.

1 to 4 are cross-sectional views illustrating a process of manufacturing a flexible current collector according to a preferred embodiment of the present invention.

(Flexible current collector structure)

First, as shown in Figure 4, the flexible current collector 1 according to a preferred embodiment of the present invention is a metal powder 22 is injected into the fine pores of the porous substrate 10, such as porous nanofiber web or nonwoven fabric A fixed conductive support 20, a conductive adhesive layer 30 formed on one surface of the conductive support 20, and a conductive metal layer 40 formed on the surface of the conductive adhesive layer 30 are included.

The conductive support 20 forms a spinning solution by dissolving an electrospinable polymer in a solvent, and then three-dimensional micropores 14 by the nanofibers 12 that are spun by spinning the spinning solution on a collector or transfer sheet. To the porous substrate 10 such as a porous nanofiber web or a nonwoven fabric having a), fine metal powder 22 is injected and fixed to secure conductivity.

The porous nanofiber web may be electrospun a mixed spinning solution in which a single polymer or at least two polymers are mixed and dissolved in a solvent, or cross each other through different spinning nozzles after dissolving different polymers in a solvent. It can be obtained by spinning.

In the case of forming a mixed spinning solution using the two kinds of polymers, for example, in the case of mixing PAN as a heat resistant polymer and PVDF as an adhesive polymer (or swellable polymer), a range of 8: 2 to 5: 5 wt% It is preferable to mix with.

When the mixing ratio of the heat-resistant polymer and the adhesive polymer is less than 5: 5 by weight, the heat resistance is poor and does not have the required high temperature characteristics. When the mixing ratio is larger than 8: 2 by weight, the strength drops and the radiation trouble occurs.

In the present invention, when preparing a spinning solution, in the case of a mixed polymer of a heat resistant polymer material and a swellable polymer material, a single solvent or a two-component mixed solvent in which a high boiling point solvent and a low boiling point solvent are mixed may be used. In this case, the mixing ratio between the two-component mixed solvent and the entire polymeric material is preferably set to about 8: 2 by weight.

In the present invention, when using a single solvent, considering that the solvent may not be well volatilized depending on the type of the polymer, after the spinning process as described below after the pre-air dry zone (Pre-Air Dry Zone) As it passes, the process may control the amount of solvent and water remaining on the surface of the porous nanofiber web.

The polymer may be used as long as it is a fibrous forming polymer capable of dissolving in a solvent to form a spinning solution and then spinning by an electrospinning method to form the nanofibers 12.

The heat resistant polymer resin usable in the present invention is a resin that can be dissolved in an organic solvent for electrospinning and has a melting point of 180 ° C. or higher, for example, polyacrylonitrile (PAN), polyamide, polyimide, polyamideimide, Aromatic polyesters such as poly (meth-phenylene isophthalamide), polysulfones, polyetherketones, polyethylene terephthalates, polytrimethylene terephthalates, polyethylene naphthalates, and the like, polytetrafluoroethylene, polydiphenoxyphosphazenes Polyphosphazenes, such as poly {bis [2- (2-methoxyethoxy) phosphazene]}, polyurethane copolymers including polyurethanes and polyetherurethanes, cellulose acetates, cellulose acetate butyrates, cellulose acetate pros Cypionate and the like can be used.

The swellable polymer resin usable in the present invention is a resin that swells in an electrolyte and can be formed into ultrafine fibers 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 Polyacrylic containing Casting reel can be given to the copolymer, polymethyl methacrylate, polymethyl methacrylate copolymers and mixtures thereof.

The porous nanofiber web is formed by dissolving a single or mixed polymer in a solvent to form a spinning solution, and then spinning the spinning solution to form a porous nanofiber web (10) consisting of ultra-fine nanofibers (12), below the melting point of the polymer It is formed by adjusting the pore size and thickness of the web by calendering at a temperature of.

The porous nanofiber web is formed by, for example, nanofibers having a diameter of 0.3 to 1.5 um, and is set to a thickness of 10 to 70 um, preferably 20 to 25 um. The size of the fine pores is set to several tens of um, the porosity is set to 50 to 90%.

In this case, the porous substrate 10 may be used alone or in combination with a porous nonwoven fabric to reinforce the strength of the porous nanofiber web and the support if necessary. The porous nonwoven fabric is, for example, a nonwoven fabric made of a double structure PP / PE fiber coated with PE on the outer circumference of the PP fiber as a core, or a PET nonwoven fabric made of polyethyleneterephthalate (PET) fibers and a nonwoven fabric made of cellulose fibers. Any one can be used.

The metal powder 22 injected into the three-dimensional micropores 14 of the porous substrate 10 to form the conductive support 20 is a metal powder 22 having a size of a few um smaller than the size of the micropores 14. ) Is mixed with a solvent to form a metal powder slurry, and then coated or sprayed on both sides of the porous substrate 10, or the porous substrate 10 is dipped into the metal powder slurry to deposit the slurry in the fine pores 14. The metal powder 22 is fixed by hot air drying and hot pressing.

The metal powder 22 may be a metal having excellent electrical conductivity as an electrode current collector, for example, nickel (Ni), copper (Cu), stainless steel (SUS), titanium (Ti), chromium (Cr) ), Manganese (Mn), iron (Fe), cobalt (Co), zinc (Zn), molybdenum (Mo), tungsten (W), silver (Ag), gold (Au), aluminum (Al) Can be used.

In this case, when the current collector 1 is used as a cathode, copper (Cu) is preferable, and when used as a cathode, aluminum (Al) is preferable.

The flexible current collector 1 of the present invention forms a conductive adhesive layer 30 formed on one surface of the conductive support 20 in order to increase the electrical conductivity on the surface of the current collector, and the conductivity formed on the surface of the conductive adhesive layer 30. The metal layer 40 is formed or the conductive metal layer 40 is formed on one surface of the conductive support 20.

When the conductive metal layer 40 is formed by the electrolytic plating or the electroless plating method, the conductive adhesive layer 30 is formed to serve as an adhesive layer and to secure conductivity.

The conductive metal layer 40 is preferably copper (Cu) when the current collector 1 is used as a cathode, and preferably aluminum (Al) when used as the anode, but the present invention is not limited thereto. Any metal having excellent electrical conductivity usable as the metal powder 22 can be used.

The conductive adhesive layer 30 is preferably made of the same metal material as the conductive metal layer 40, and is formed to, for example, 1 μm or less by PVD (Physical Vapor Deposition) methods such as sputtering, vacuum deposition, and ion plating. .

Flexible current collector 1 of the present invention configured as described above is a porous substrate made of a porous nanofiber web or nonwoven fabric having a three-dimensional micropores 14 by the nanofibers 12, the conductive support 20 is electrospun ( 10), the fine metal powder 22 is injected to secure conductivity, and thus has a fixed structure, and thus has flexibility and high electrical conductivity.

In addition, the flexible current collector 1 of the present invention forms the conductive metal layer 40 on the surface of the conductive support 20 through the conductive adhesive layer 30, or directly on the surface of the conductive support 20. By forming a thin film is made excellent electrical conductivity.

(Battery structure)

Referring to FIG. 5, the secondary battery configured using the flexible current collector according to the present invention may constitute a lithium ion battery or a lithium polymer battery.

When the secondary battery forms a full cell, the secondary battery includes a positive electrode 5, a separator or gel polymer electrolyte 6, and a negative electrode 7.

The positive electrode 5 includes the positive electrode active material layer 50 on one surface of the positive electrode current collector 1a, and the negative electrode 7 includes the negative electrode active material layer 60 on one surface of the negative electrode current collector 1b. .

However, the positive electrode 5 may be disposed to face the negative electrode 7 and may include a pair of positive electrode active material layers on both sides of the positive electrode current collector 1a to form a bicell.

The positive and negative electrode current collectors 1a and 1b are constructed using the flexible current collector 1 according to the present invention.

First, the positive electrode current collector 1a is formed on one surface of the conductive support 20 by, for example, an aluminum (Al) adhesive layer 30 made of aluminum (Al) by a sputtering method, and an aluminum (Al) adhesive layer ( The aluminum (Al) metal layer 40 is formed on the upper portion of the substrate 30 by electrolytic plating or electroless plating.

In addition, the negative electrode current collector 1b forms a copper (Cu) adhesive layer 30 made of, for example, copper (Cu) on one surface of the conductive support 20 by a sputtering method, and the copper (Cu) adhesive layer 30. The copper (Cu) metal layer 40 is formed on the upper part of the panel by electrolytic plating or electroless plating.

The cathode active material layer 50 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.

The negative electrode active material layer 60 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 5 and the negative electrode 6 prepare a slurry by mixing a predetermined 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, the positive and negative electrodes described above. It can be obtained by casting, drying and rolling the prepared slurry on both sides of the current collector (1a, 1b).

The positive electrode active material layer 50 and the negative electrode active material layer 60 each include PTFE (Polytetrafluoroethylene) for preventing cracking of electrodes and preventing peeling of the positive electrode active material and the negative electrode active material from the positive electrode and negative electrode current collectors 1a and 1b. can do. In this case, the PTFE is preferably contained in less than 0.5 ~ 20wt%, preferably less than 5wt%.

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 to the positive electrode current collector (1a), and the negative electrode as MCMB (mesocarbon microbeads), super-P A slurry composed of carbon and PVdF can be cast and used for the negative electrode current collector 1b. 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 adhesive force between the particles and the current collector.

When the secondary battery constitutes a lithium ion battery, an electrode assembly is formed by interposing a separator 6 between the positive electrode 5 and the negative electrode 7, placed in an aluminum or aluminum alloy can or a similar container, and then cap assembly. After the opening is finished, an electrolyte is injected to manufacture a lithium ion battery.

In addition, when the secondary battery constitutes a flexible battery, as described later, a separator 6 is formed between the positive electrode 5 and the negative electrode 7 to form an electrode assembly, and then placed in a pouch. An organic electrolyte solution containing a solute of a solvent, a lithium salt, a monomer for forming a gel polymer, and a polymerization initiator is injected to impregnate the separator 6, and a gel polymer electrolyte is formed on the separator by polymerizing the gel polymer forming monomer. A polymer battery can be comprised.

In this case, the separator is laminated on one side of the porous non-woven fabric that serves as a support, and includes a porous polymer web layer that serves as an adhesive layer and an ion-moisture layer when in close contact with the opposite electrode, a portion of the porous polymer web layer A composite porous membrane may be used that is embedded in the surface layer of the porous nonwoven fabric to block pores of the surface laminated with the porous nonwoven fabric to lower the porosity of the porous nonwoven fabric.

In addition, the separator is laminated on one side of the porous non-woven fabric that serves as a support, and includes an inorganic porous polymer film layer that serves as an adhesive layer and an ion-moisture layer when in close contact with the opposite electrode, a part of the inorganic porous polymer film layer In order to block the pores of the surface laminated with the porous nonwoven fabric may be incorporated into the surface layer of the porous nonwoven fabric may use a composite porous separator that lowers the porosity of the porous nonwoven fabric.

Furthermore, the separator may serve as a support and have a first melting point and a first porosity; A first porous polymer web layer laminated on one side of the porous nonwoven fabric and serving as an adhesive layer when in close contact with an opposite electrode; And a second porous polymer web layer laminated on the other side of the porous nonwoven fabric and composed of nanofibers of a heat resistant polymer, wherein the first porous polymer web layer and the second porous polymer web layer each have a first melting point of the porous substrate. It is possible to use a composite porous separator having a shutdown function having a higher melting point and porosity equal to or similar to that of the first porosity.

In addition, the separator is a porous nonwoven fabric having a support role and having a first melting point and a first porosity; An inorganic porous polymer film layer laminated on one side of the porous nonwoven fabric and serving as an adhesive layer when in close contact with an opposite electrode; And a second porous polymer web layer laminated on one side of the porous nonwoven fabric and composed of nanofibers of a heat resistant polymer, wherein the second porous polymer web layer has a higher melting point and a first pore than the first melting point of the porous nonwoven fabric. Composite porous membranes having a shutdown function having the same or similar porosity can be used.

Furthermore, the separator is formed of a first non-porous polymer film layer made of a polymer material capable of conducting electrolyte ions, swelling in an electrolyte, and an ultrafine fibrous shape of a mixture of a heat-resistant polymer or a heat-resistant polymer and a swellable polymer and inorganic particles. It comprises a porous polymer web layer made of, wherein the first non-porous polymer film layer and the porous polymer web layer may be formed separately on both sides of the negative electrode and the positive electrode, or may be formed laminated on either side of the positive electrode and the negative electrode.

In this case, the inorganic particles are Al ₂ O ₃ , TiO ₂ , BaTiO ₃ , Li ₂ O, LiF, LiOH, Li ₃ N, BaO, Na ₂ O, Li ₂ CO ₃ , CaCO ₃ , LiAlO ₂ , SiO ₂ , SiO, SnO, SnO ₂ , PbO ₂ , ZnO, P ₂ O ₅ , CuO, MoO, V ₂ O ₅ , B ₂ O ₃ , Si ₃ N ₄ , CeO ₂ , Mn ₃ O ₄ , Sn ₂ P ₂ O ₇ , Sn ₂ B ₂ O ₅ , Sn ₂ BPO ₆ and at least one selected from the mixtures thereof can be used.

When the mixture consists of a heat resistant polymer or a heat resistant polymer and a swellable polymer and inorganic particles, the content of the inorganic particles is preferably contained in the range of 10 to 25% by weight based on the total mixture when the size of the inorganic particles is between 10 and 100 nm. . 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.

In addition, when the mixture consists of a heat resistant polymer, a swellable polymer and inorganic particles, the heat resistant polymer and the swellable polymer are preferably mixed in a weight ratio of 5: 5 to 7: 3, and more preferably 6: 4. In this case, the swellable polymer is added as a binder to help bond between the fibers.

When the mixing ratio of the heat resistant polymer and the swellable polymer is less than 5: 5 by weight, the heat resistance is poor and does not have the required high temperature characteristics. When the mixing ratio is larger than 7: 3 by weight, the strength drops and the radiation trouble occurs.

In addition, as the separator, swelling is performed in the electrolyte, and any separator capable of separating the positive electrode and the negative electrode may be used without limitation.

As the electrolyte used to construct the lithium ion battery, an organic electrolyte containing a non-aqueous organic solvent and a solute of lithium salt is used.

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.

In addition, the electrolyte according to the present invention includes a lithium salt, the lithium salt acts as a source of lithium ions in the battery to enable the 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 , 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 and include one or more or mixtures thereof.

When the electrolyte is injected into the casing or pouch that accommodates and seals the can or the electrode assembly, the porous polymer web or the inorganic porous polymer film layer forming the separator 6 swells while being gelled with the electrolyte.

A portion of the porous polymer web layer or the inorganic porous polymer film layer in which the swelling is pushed into the large pores of the porous nonwoven fabric may block the pore inlet of one side of the porous nonwoven fabric to lower the porosity.

Furthermore, in the present invention, the porous nonwoven fabric is used as a substrate, and since one side of the nonwoven fabric is made of a PVDF inorganic porous polymer film layer, the inorganic porous polymer film layer having excellent adhesion is adhered to the surface of the negative electrode to form dendrite. It serves to suppress.

On the other hand, when the secondary battery constitutes a lithium polymer battery, a polymer electrolyte is inserted between the positive electrode 5 and the negative electrode 7.

In this case, the polymer electrolyte is, for example, a porous polymer web layer made of a plurality of nanofibers or an inorganic porous polymer film layer and a composite porous separator in which a porous nonwoven fabric is laminated, an organic polymer in which a monomer and a polymerization initiator for forming a gel polymer are mixed. It consists of the gel polymer part by which the gel polymer of a gel state is synthesize | combined by the polymerization reaction of a monomer as an electrolyte solution impregnates and undergoes the gelation heat processing process.

The gel polymer portion of the polymer electrolyte is filled with the organic electrolyte solution in which the composite polymer separator and the polymerization initiator are mixed in a state in which the composite porous separator 6 is sandwiched between the positive electrode 5 and the negative electrode 7 and integrated into a case. After the gelation heat treatment step, the gel polymer in the gel state is synthesized by the polymerization of the monomers.

The gel polymer electrolyte 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.

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 ℃.

To this end, the organic electrolyte contained in the composite porous separator 6 includes a non-aqueous organic solvent, a solute of a lithium salt, a monomer for forming a gel polymer, and a polymerization initiator.

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.

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.

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.

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.

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% by weight, 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.

Examples 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 And azo compounds such as 2-Azobis (Methylbutyronitrile), AIBN (Azobis (iso-butyronitrile), AMVN (Azobisdimethyl-Valeronitrile), and the like. Reaction with the monomer forms a gel polymer electrolyte, i.e. a gel polymer moiety.

In the present invention, it is preferable that the gel polymer electrolyte forming the gel polymer portion is made of a polymer having excellent conductivity so as to serve as a path for transporting lithium ions that are oxidized or reduced in the cathode and the anode during charging and discharging of the battery.

In this case, since the gel polymer forming monomer proceeds rapidly to form a gel polymer, the composite porous separator 6 maintains a 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.

In the above description, the current collector is formed on one side of the conductive support so that the current collector is suitable for the case where the secondary battery constitutes the full cell, but the current collector is the conductive support so that the current collector is suitable for the case where the secondary battery constitutes the bicell. It is also possible to form a conductive metal film on both sides of the.

Further, in the present invention, it is also possible to construct a polymer battery using other well-known polymer electrolytes and electrodes other than the gel polymer electrolyte described in the above embodiments.

In addition, the conductive metal layer and the conductive adhesive layer may be formed of a multilayer structure as well as a single layer structure, respectively.

In the above, the present invention has been illustrated and described by way of specific preferred embodiments, but the present invention is not limited to the above-described embodiments, and the general knowledge in the technical field to which the present invention pertains falls within the scope of the present invention. Various changes and modifications will be possible by those who have the same.

The present invention can be applied to a flexible secondary battery including a lithium ion secondary battery, a lithium polymer secondary battery, a supercapacitor, which can be configured using a flexible current collector, and its manufacture.

Claims

A conductive support formed by injecting metal powder into the porous substrate; And

Flexible current collector comprising a conductive metal layer formed on at least one side of the conductive support.
The method of claim 1,

Flexible current collector further comprises a conductive adhesive layer interposed between the conductive support and the conductive metal layer.
The method of claim 2,

And the conductive metal layer and the conductive adhesive layer are made of the same metal.
The method of claim 3,

The metal is Cu or Al flexible current collector.
The method of claim 1,

The porous substrate is a flexible current collector, which is one of a nanofiber web, a nonwoven fabric, and a laminated structure of the nanofiber web and a nonwoven fabric.
The method of claim 5,

The fiber diameter of the porous substrate is 0.3 to 1.5um, the thickness of the porous substrate is 10 to 70um flexible current collector.
The method of claim 6,

The thickness of the porous substrate is 20 to 25um flexible current collector.
The method of claim 1,

The pore size of the porous substrate is several tens of um, the porosity is 50 to 90% of a flexible current collector.
The method of claim 1,

The thickness of the conductive metal layer is a flexible current collector of 1 to 5um.
Injecting a slurry in which the metal powder and the binder are mixed into the fine pores of the porous substrate to form a conductive support; And

Forming a conductive metal layer on at least one side of the conductive support.
The method of claim 10,

Before forming the conductive metal layer, further comprising forming a conductive adhesive layer on the conductive support using the same material as the conductive metal layer.
The method of claim 10,

The porous substrate is a manufacturing method of a flexible current collector, which is one of a nanofiber web, a nonwoven fabric, and a laminated structure of the nanofiber web and a nonwoven fabric.
A secondary battery comprising a positive electrode, a negative electrode, a separator and an electrolyte interposed between the positive electrode and the negative electrode,

The positive electrode includes a first current collector and a positive electrode active material formed on one or both surfaces of the first current collector,

The negative electrode includes a second current collector and a negative electrode active material formed on one side or both sides of the second current collector,

The first and second current collectors are secondary batteries, characterized in that the flexible current collector according to any one of claims 1 to 9.
The method of claim 13,

The electrolyte is composed of an organic electrolyte containing a non-aqueous organic solvent and a solute of lithium salt, a monomer for forming a gel polymer and a polymerization initiator,

After the electrolyte is impregnated in the porous membrane, the secondary battery, characterized in that to form a gel polymer electrolyte by polymerizing the gel polymer forming monomer.
The method of claim 13,

The electrolyte is a secondary battery comprising an organic electrolyte containing a non-aqueous organic solvent and a solute of lithium salt.
The method of claim 13,

The separator is

A porous nonwoven fabric serving as a support; And

It is laminated on one side of the porous non-woven fabric, and includes a porous polymer web layer or an inorganic porous polymer film layer that serves as an adhesive layer and an ion-moisture layer when in close contact with the opposite electrode,

Part of the porous polymer web layer or inorganic porous polymer film layer is a secondary battery characterized in that it is embedded in the surface layer of the porous nonwoven fabric to block the pores of the surface laminated with the porous nonwoven fabric to reduce the porosity of the porous nonwoven fabric.
The method of claim 13,

The separator is

A porous nonwoven fabric serving as a support and having a first melting point and a first porosity;

A first porous polymer web layer laminated on one side of the porous nonwoven fabric and serving as an adhesive layer when in close contact with an opposite electrode; And

It is laminated on the other side of the porous nonwoven fabric, and includes a second porous polymer web layer made of nanofibers of heat-resistant polymer,

And the first porous polymer web layer and the second porous polymer web layer each have a melting point higher than the first melting point of the porous substrate and the same or similar porosity as the first porosity.
The method of claim 13,

The positive electrode active material and the negative electrode active material, the secondary battery, characterized in that it comprises a PTFE (Polytetrafluoroethylene) for preventing the crack of the electrode and the peeling of the positive electrode active material and the negative electrode active material from the first and second current collector, respectively.
The method of claim 18,

The PTFE is a secondary battery characterized in that it contains 0.5 ~ 20wt%.