KR101576144B1 - Polymer Electrolyte, Lithium Secondary Battery Using the Same and Manufacturing Method thereof - Google Patents

Abstract

The nanofiber constituting the porous polymer web forms a shell-core structure by mixing the swellable polymer and the non-swellable polymer to form a shell-core structure, and the swellable polymer shell disposed on the outer side is disposed inside even if the gelation is performed by the organic electrolytic solution The present invention relates to a polymer electrolyte, a lithium secondary battery using the polymer electrolyte, and a method for manufacturing the polymer electrolyte, which can prevent short-circuiting between the two electrodes by maintaining the web shape by the non-swellable polymer core.
The polymer electrolyte of the present invention comprises a swellable polymer shell consisting of a swellable polymer having a shell-core structure along its longitudinal direction and arranged on the outside and swelling in an organic electrolytic solution, and a plurality of non-swellable polymer cores made of a non-swellable polymer A porous polymer web comprising nanofibers; And an organic electrolytic solution impregnated in the porous polymer web and having a lithium salt dissolved in a non-aqueous organic solvent. As the gelation process is performed, the swellable polymer shell disposed outside the nanofibers is gelated by the organic electrolytic solution , And the non-swellable polymer core disposed inside is characterized by retaining the web shape.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polymer electrolyte, a lithium secondary battery using the polymer electrolyte,

The present invention relates to a polymer electrolyte, a lithium secondary battery using the polymer electrolyte, and a method of manufacturing the same. More particularly, the nanofiber constituting the porous polymer web forms a shell-core structure by mixing and dispersing a swelling polymer and a non-swelling polymer, Swellable polymer shell is a polymer electrolyte which can prevent short circuit between two electrodes due to the web shape maintained by a non-swellable polymer core disposed inside even if the gelation is performed by an organic electrolytic solution, thereby achieving safety and thinning simultaneously. And a method of manufacturing the same.

Conventionally, as an electrolyte of a lithium secondary battery, an electrolyte in which a non-aqueous electrolytic solution is impregnated with a film having a pore called a separator has been used. In recent years, a lithium secondary battery (polymer battery) using a polymer electrolyte made of a polymer rather than an electrolytic solution of such liquid has attracted attention.

Such a polymer battery uses a gel electrolyte in which a polymer electrolyte is impregnated with a liquid electrolyte. Since the electrolyte is retained in the polymer, it is difficult for the liquid to leak out, thus improving the safety of the battery, and also allowing the shape of the battery to be freely made.

Since the polymer electrolyte has low conductivity of lithium ion as compared with an electrolyte composed solely of an electrolytic solution, a method of reducing the thickness of the polymer electrolyte has been carried out. However, when the polymer electrolyte is made thin, the mechanical strength thereof is reduced, and the anode and the cathode are short-circuited at the time of manufacturing the battery, and the polymer electrolyte is liable to be broken.

Therefore, conventionally, as shown in Japanese Unexamined Patent Publication (Kokai) No. 2006-140052, a method of improving the mechanical strength of a solid electrolyte by adding an inorganic oxide such as alumina to the electrolyte has been proposed. In addition to alumina, inorganic oxides such as silica or lithium aluminate have been proposed.

However, when an inorganic oxide such as alumina is added to the solid electrolyte, the conductivity of the electrolyte is greatly deteriorated. In addition, when the lithium ion secondary battery including such a solid electrolyte is repeatedly charged and discharged, there is a problem that the electrolyte and the inorganic oxide react with each other and the charge-discharge cycle characteristics of the lithium ion secondary battery are significantly lowered.

On the other hand, conventional polymer electrolytes were mainly produced by using polyethylene oxide (hereinafter referred to as "PEO") as a polymer matrix, but their ionic conductivity was only about 10 ^-8 S / cm at room temperature and could not be commercialized. Recently, a polymer electrolyte in the form of gel or hybrid has been developed which exhibits an ionic conductivity of 10 ^-3 S / cm or more at room temperature.

U.S. Patent No. 6,509,123 and Japanese Unexamined Patent Publication No. 2000-299129 each propose a gel-type polymer electrolyte in a unique manner.

U.S. Patent No. 6,509,123 adopts PVDF-HFP (polyvinylidene fluoride hexafluoropropylene) or the like as a polymer and LiPF ₆ dissolved in EC (ethylene carbonate) and PC (propylene carbonate) as an electrolytic solution The polymer and electrolyte are mixed with a DMC (dimethyl carbonate) solvent, the mixture is coated on the electrode surface, and DMC is volatilized to prepare a gel polymer on the electrode. Then, in order to prevent short circuiting, the battery is wound by winding with a polyolefin-based separator.

On the other hand, in Japanese Patent Laid-Open No. 2000-299129, a battery is produced by a winding method using an anode, a cathode and a polyolefin-based separator in advance, and then PVDF (polyvinylidene fluoride), PMMA (polymethyl methacrylate) (Polyethylene glycol dimethyl acrylate) and an initiator were mixed with an appropriate organic carbonate mixture, injected into a cell already prepared, and then crosslinked under appropriate conditions to prepare a gel-type polymer electrolyte. In this case, the gel-type polymer electrolyte is characterized by being formed inside the cell after the cell assembly.

However, the above two processes for producing a gel-type polymer electrolyte are very complicated, and it is known that there is a problem in mass productivity. In addition, there is a disadvantage in that there is a limit to improvement in battery performance and safety. That is, as the content of polymer such as PVDF-HFP, PVDF, or PMMA is increased, the safety of the battery is improved, but the performance of the battery is significantly deteriorated.

The above-described gel-type polymer electrolyte of the prior art includes gel-like polymers that are not soluble in electrolytic solution due to characteristics of the manufacturing process.

However, when a method is employed in which a separator is prepared by coating an electrolyte-soluble polymer on one side or both sides of a separator and the separator is interposed between the positive and negative electrodes and then the electrolyte is injected after assembling the cell first, Soluble polymer coated on the membrane is dissolved in the electrolytic solution to thereby produce an electrolyte having a gel state or a high viscosity liquid state close to a liquid state and the electrolytic solution can be produced in a conventional manner by replacing the high- And can be easily formed by injecting a low-viscosity electrolytic solution. The battery including such an electrolyte having a high viscosity improves safety compared to a battery including a liquid electrolyte, whereas an electrolyte-soluble polymer capable of minimizing deterioration of the battery, unlike a battery including a conventional gel-type polymer electrolyte, Coated membranes and electrochemical devices have been proposed in Korean Patent Laid-Open Publication No. 10-2005-42456.

The separation membrane proposed in Korean Patent Laid-Open Publication No. 10-2005-42456 is difficult to uniformly coat an electrolyte-soluble polymer on the separation membrane, making it difficult to form a uniform electrolyte membrane, and it is difficult to make the electrolyte membrane close to and thin.

In addition, U.S. Patent No. 5,219,679 and U.S. Patent No. 5,240,790 disclose gel-type polyacrylonitrile (PAN) -based polymer electrolytes. The gel-based PAN-based polymer electrolyte is prepared by injecting a solvent compound (hereinafter referred to as "organic electrolyte solution") formed between a lithium salt and an organic solvent such as ethylene carbonate or propylene carbonate in a PAN-based polymer matrix. However, in spite of these advantages, the polymer electrolyte has a disadvantage in that the electrolyte is somewhat backed away and the mechanical stability, that is, the strength is lowered. In particular, such weak strength properties can cause significant problems in the manufacture of electrodes and batteries.

U.S. Patent No. 5,460,904 discloses a polyvinylidene fluoride (PVdF) based polymer electrolyte in the form of a hybrid. The hybrid type PVdF polymer electrolyte is prepared by preparing a polymer matrix to have a submicron porosity and then injecting an organic electrolytic solution into the small pores. The PVDF polymer electrolyte is excellent in compatibility with organic electrolytes, The electrolytic solution is advantageous in that it can be used as a safe electrolyte without leaking, and the polymer matrix can be produced in the atmosphere because the organic solvent electrolyte is injected later.

However, since the extraction process of the plasticizer and the impregnation process of the organic solvent electrolyte are required in the production of the polymer electrolyte, the manufacturing process is complicated.

Korean Patent No. 10-0569185 proposes a hybrid polymer electrolyte comprising a porous polymer matrix composed of ultrafine polymer fibers having a diameter of 1-3000 nm and a polymer electrolyte embedded therein, and a lithium secondary battery using the hybrid polymer electrolyte.

The hybrid polymer electrolyte comprises an ultrafine fibrous porous polymer matrix composed of a polymer having a diameter of 1 to 3000 nm and an organic electrolyte solution in which a polymer, a plasticizer and a lithium salt embedded in pores of the ultrafine fibrous porous polymer matrix are dissolved in an organic solvent The polymer is dissolved in an organic solvent, and then a porous polymer matrix having a diameter of 1-3000 nm is prepared by charge induction spinning. The polymer, plasticizer and organic electrolyte are mixed and poured into the pores of the polymer matrix. And the dissolved polymer electrolyte is injected to prepare a hybrid type polymer electrolyte.

Accordingly, Korean Patent No. 10-0569185 discloses a method of preparing a hybrid polymer electrolyte by first preparing a hybrid polymer electrolyte, placing the resulting hybrid polymer electrolyte between a cathode and an anode, or applying both surfaces of one electrode and one electrode of another electrode , The assembly, the casing, and the electrolyte injection process are carried out. Therefore, there is a problem that the number of steps increases and becomes complicated because a hybrid type polymer electrolyte must be separately manufactured.

In addition, Korean Patent No. 10-0569185 discloses a method of preparing a hybrid polymer electrolyte by first forming a polymer electrolyte and then casting it onto a porous polymer matrix by a die casting method to obtain a viscosity of about several thousand cps, The electrolyte solution is introduced into the matrix, so that the uniform introduction of the polymer electrolyte solution can not be ensured.

Furthermore, Korean Patent No. 10-0569185 discloses that an electrode assembly is placed in a battery case, an organic electrolytic solution is injected into the battery case, and the battery is sealed to form a battery, and does not have a separate gelling process.

Korean Patent No. 10-0637481 discloses a non-woven fabric comprising a positive electrode, a polymer electrolyte, and a negative electrode, wherein the polymer electrolyte comprises a non-woven fabric having at least gelled and non-gelled fibers that are easily gelled by an organic electrolytic solution, Wherein the mixing ratio of the gelled gelled fiber to the non-gelled fiber is 3: 97 to 75:25 by weight and the content of vinyl acetate is 5 wt% By weight to 20% by weight or less of a polyacrylonitrile-vinyl acetate copolymer.

The polymer electrolyte proposed in Korean Patent No. 10-0637481 impregnates an organic electrolytic solution into a nonwoven fabric having at least gelled fibers and non-gelled fibers, so that the uniformity of the gelled fiber portion in which gelation is carried out by the impregnated organic electrolyte is ensured Uniform ion conductivity can not be ensured and there is also possibility of internal short-circuiting. Since it has a non-woven form, it is difficult to uniformly form a thin film even if gelation is performed.

In Korean Patent No. 10-1208698, two different electrodes; Electro-electrospinning (AES) of a mixed solution of 50-70 wt% heat-resistant polymer material having a melting point of 180 ° C or higher and 30-50 wt% swelling polymer material swelling in the electrolyte is interposed between the two electrodes A heat-resistant ultrafine fibrous porous separator containing the obtained ultrafine fibrous phase; And a secondary battery including an electrolyte or an electrolyte have been proposed by the present applicant.

However, Korean Patent No. 10-1208698 discloses a method of using a porous separator made of ultrafine fibers obtained by spinning a mixed solution of a heat-resistant polymer material and a swellable polymer material, and has advantages of having a core-shell structure and a core- And did not recognize the condition of formation.

Japanese Laid-Open Patent Publication No. 2006-140052 U.S. Patent No. 6,509,123 Japanese Patent Application Laid-Open No. 2000-299129 Korean Patent Publication No. 10-2005-42456 U.S. Patent No. 5,219,679 U.S. Patent No. 5,240,790 U.S. Patent No. 5,460,904 Korean Patent No. 10-0569185 Korean Patent No. 10-0637481 Korean Patent No. 10-1208698

The present inventors have found that the nanofibers produced by mixing a swellable polymer in which an electrolyte is swollen to gel and a non-swellable polymer have a core-shell structure when the molecular weight difference between the two polymers to be mixed is not less than a set value. In this case, a non-swelling polymer having a large molecular weight is placed in the core portion of the nanofiber and a swelling polymer having a small molecular weight is used. . In addition, the non-swellable polymer has a relatively high melting point because it has a larger molecular weight than the swellable polymer.

Therefore, when the gelation is performed at a temperature higher than the melting point of the swelling polymer and lower than the melting point of the non-swelling polymer in the heat treatment step for gelation after the organic electrolytic solution is injected, the swellable polymer shell disposed outside the nanofiber, The non-swellable polymer core disposed inside maintained a matrix shape as only a slight swelling occurred and the chain was kept unbroken. The present invention has been made on the basis of this finding.

SUMMARY OF THE INVENTION [0006] Accordingly, the present invention has been made to solve the above-mentioned problems of the prior art, and it is an object of the present invention to provide a nanocomposite structure in which nanofibers constituting a porous polymer web form a shell- A non-swellable polymer core disposed on the non-swellable polymer core maintains a web shape uniformly with respect to the entire polymer electrolyte membrane, thereby preventing a short circuit between the positive electrode and the negative electrode, thereby achieving safety; a lithium secondary battery using the polymer electrolyte; .

Another object of the present invention is to provide a polymer electrolyte capable of ensuring fast and uniform electrolyte impregnation of an organic electrolyte by using a porous polymer web composed of nanofibers having a core-shell structure as an electrolyte matrix, a lithium secondary battery using the same, .

It is still another object of the present invention to provide a method for producing a porous electrolyte membrane in which the swellable polymer shell disposed on the outer periphery of the nanofibers constituting the porous electrolyte matrix is converted into a solid electrolyte having almost no electrolyte solution, And a polymer electrolyte capable of increasing ionic conductivity with thinning, a lithium secondary battery using the polymer electrolyte, and a method of manufacturing the same.

It is another object of the present invention to provide a non-swellable porous thin film sheet which can prevent the phenomenon of expansion and contraction of the electrode assembly during charging and discharging, thereby preventing separation between the electrolyte and the electrode A lithium secondary battery capable of suppressing an increase in interfacial resistance and a method of manufacturing the same.

In order to achieve the above-mentioned object, the polymer electrolyte of the present invention comprises a swellable polymer shell made of a swellable polymer having a shell-core structure along its longitudinal direction and disposed on the outside and swelling in an organic electrolytic solution, and a non-swellable polymer A porous polymer web comprising a plurality of nanofibers comprising a non-swellable polymer core; And an organic electrolytic solution impregnated in the porous polymer web and having a lithium salt dissolved in a non-aqueous organic solvent. As the gelation process is performed, the swellable polymer shell disposed outside the nanofibers is gelated by the organic electrolytic solution , And the non-swellable polymer core disposed inside is characterized by retaining the web shape.

The lithium secondary battery according to the present invention comprises a positive electrode and a negative electrode capable of intercalating and deintercalating lithium, and a polymer electrolyte disposed between the positive and negative electrodes, wherein the polymer electrolyte has a shell-core structure along the longitudinal direction A porous polymer web comprising a plurality of nanofibers comprising a swellable polymer shell comprising a swellable polymer swellable in an organic electrolytic solution and a non-swellable polymer core comprised of a non-swellable polymer; And an organic electrolytic solution impregnated in the porous polymer web and having a lithium salt dissolved in a non-aqueous organic solvent. As the gelation process is performed, the swellable polymer shell disposed outside the nanofibers is gelated by the organic electrolytic solution , And the non-swellable polymer core disposed inside is characterized by retaining the web shape.

The method for preparing a lithium secondary battery according to the present invention comprises the steps of: dissolving a non-swelling polymer and a swelling polymer in a solvent to form a mixed polymer spinning solution; A swellable polymer shell comprising a swellable polymer swelling in an organic electrolytic solution outside a non-swellable polymer core made of a non-swellable polymer by spinning the mixed polymer spinning solution, and a plurality of nanofibers each having a shell- Forming a porous polymer web; Forming an electrode assembly in which the porous polymer web is interposed between a positive electrode and a negative electrode each of which is formed of a plurality of unit electrode cells; Inserting the electrode assembly into a case and injecting an organic electrolyte; And performing a gelation heat treatment to swell the swellable polymer shell disposed outside the nanofibers with an organic electrolytic solution, wherein the non-swellable polymer core disposed inside the nanofibers maintains a web shape .

The forming of the electrode assembly may include forming an electrode strip by coating an electrode active material layer on at least one side of the strip-shaped electrode current collector of the positive electrode and the negative electrode, Performing sequential blanking while transferring the electrode strip in a step-by-step manner to partially separate and form a plurality of first unit electrode cells from the electrode strip; Sealing the plurality of first unit electrode cells with a pair of porous polymer webs on both sides while continuously transporting the plurality of first unit electrode cells; And inserting and stacking a plurality of second unit electrode cells of the other one of the anode and the cathode between the plurality of sealed first unit electrode cells.

According to another aspect of the present invention, there is provided a method of manufacturing a lithium secondary battery, comprising: forming a plurality of unit anode cells and a plurality of unit cells each using a pair of porous polymer webs each comprising a plurality of nanofibers each comprising a non-swelling polymer and a swellable polymer; Forming an electrode assembly by alternately laminating unit cathode cells of the unit cell; Taping the electrode assembly with a compression band; Inserting the electrode assembly into a case and injecting an organic electrolyte; And performing a gelling heat treatment.

According to another aspect of the present invention, there is provided a lithium secondary battery comprising a pair of porous polymer webs each having a plurality of nanofibers each composed of a non-swelling polymer and a swellable polymer, An electrode assembly alternately stacked while separating cathode cells; A pressing band for taping the outer periphery of the electrode assembly; And a case filled with an organic electrolyte. The swellable polymer shell disposed outside the nanofibers as the gelation process is performed is gelled by an organic electrolytic solution, The non-swellable polymer core disposed inside is characterized by maintaining a web shape.

As described above, in the present invention, a polymer web formed by nanofibers spun by mixing a swellable polymer in which an electrolyte is swollen and gelated and a non-swellable polymer is used as a porous matrix, and uniform electrolyte infiltration Can be guaranteed.

In addition, in the present invention, the nanofibers constituting the porous polymer web form a shell-core structure, and the swellable polymer shell disposed on the outer side of the nanofibers is gelled, but the non-swellable polymer core disposed inside is uniform The short circuit between the positive electrode and the negative electrode can be prevented and safety can be ensured, and at the same time, the occurrence of short circuit due to the precipitation of dendrite crystals of lithium can be prevented.

Further, since the non-swellable polymer core for retaining the web shape remains between the positive electrode and the negative electrode, the polymer electrolyte itself can be made thinner than the swellable polymer shell filled in the positive and negative electrodes, and the polymer electrolyte itself can be made thinner by uniform impregnation The ionic conductivity of the polymer can be increased.

According to the present invention, since the thin film adhesive layer is provided on the outer side of the polymer electrolyte, the adhesion between the positive electrode and the negative electrode can be improved and the short circuit due to the growth of the dendrite of lithium can be prevented.

In addition, according to the present invention, taping the outside of the electrode assembly with a non-swellable thin film band induces expansion and contraction of the electrode assembly in the lateral direction instead of the vertical direction of the electrode assembly during charging and discharging, As the phenomenon is prevented, the increase of the interface resistance can be suppressed, and the decrease of the OCV (Open Circuit Voltage) can be minimized.

Further, in the present invention, the positive electrode and the negative electrode are filled with the swollen polymer in a state in which a part of the swellable polymer is continuous with the polymer electrolyte, thereby bonding the positive electrode and the negative electrode to the polymer electrolyte, thereby decreasing the OCV (open circuit voltage) Can be minimized.

1 is a sectional view showing a lithium secondary battery according to a first preferred embodiment of the present invention,
2 is a cross-sectional view illustrating a lithium secondary battery according to a second preferred embodiment of the present invention,
3 is a process sectional view showing a process for producing a porous polymer web used as a polymer electrolyte according to the present invention,
4 is a process sectional view showing a sealing process of a porous polymer web used as an anode and a polymer electrolyte according to the present invention,
Figure 5 is a schematic cross-sectional view of an electrode assembly assembled in accordance with the present invention,
Figure 6 is a schematic plan view of an electrode assembly assembled in accordance with the present invention,
7 is a flowchart showing a process of assembling a lithium secondary battery according to the present invention.

The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings, in which: It can be easily carried out.

In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail.

Hereinafter, in the present specification, the polymer electrolyte is obtained by assembling a porous polymer web together with a positive electrode and a negative electrode into a case, injecting an organic electrolytic solution into a case, and then introducing an organic electrolytic solution into the porous polymer web and passing through a gelation process. Refers to an inorganic-ball type gel-type polymer electrolyte in which the organic solvent does not substantially remain.

FIG. 1 is a cross-sectional view illustrating a lithium secondary battery according to a first embodiment of the present invention, and FIG. 2 is a cross-sectional view illustrating a lithium secondary battery according to a second preferred embodiment of the present invention.

1, a lithium secondary battery according to a first preferred embodiment of the present invention, namely, a lithium polymer battery, includes an anode 1, an inorganic porous gel electrolyte 5, And a cathode (3).

The positive electrode 1 has a positive electrode active material layer 11b on one surface of a positive electrode current collector 11a and the negative electrode 3 has a negative electrode active material layer 13b on one surface of a negative electrode current collector 13a .

However, the positive electrode 1 may be disposed opposite to the negative electrode 3 and may include a pair of positive electrode active material layers on both sides of the positive electrode collector 11a to form a bi-cell.

The positive electrode active material layer (11b) is and reversibly including a positive electrode active material capable of migration intercalation and de-intercalation of lithium ions, and a typical example of such a positive electrode active material, LiCoO _2, LiNiO _2, LiNiCoO _2, LiMn ₂ O ₄ , LiFeO ₂ , V ₂ O ₅ , V ₆ O ₁₃ , TiS, MoS, or a substance capable of absorbing and releasing lithium such as an organic disulfide compound or an organic polysulfide compound. However, in the present invention, it is of course possible to use other kinds of cathode active materials in addition to the cathode active material.

The negative electrode active material layer 13b includes a negative electrode active material capable of intercalating and deintercalating lithium ions. The negative electrode active material may include a carbon-based negative electrode active material of crystalline or amorphous carbon, carbon fiber, or carbon composite material , Tin oxides, lithium-modified ones, lithium, lithium alloys, and mixtures thereof. However, the present invention is not limited to the above-mentioned negative electrode active material.

The positive electrode 1 and the negative electrode 3 may be prepared by mixing an appropriate amount of an active material, a conductive agent, a binder and an organic solvent to prepare a slurry as in a method generally used in a conventional lithium ion battery, 11a, 13a by casting slurry prepared on both sides of aluminum or copper foil or mesh, drying and rolling.

For example, a positive electrode is formed by casting a slurry composed of LiCoO ₂ , Super-P carbon, and PVdF as an active material, a conductive agent, and a binder on an aluminum foil, and using a negative electrode such as MCMB (mesocarbon microbeads), Super- The slurry may be cast on a copper foil. In each of the positive electrode and the negative electrode, it is preferable to carry out roll pressing to increase the adhesive force between the particles and the metal foil after each slurry is cast.

The polymer electrolyte 5 is prepared by mixing a swellable polymer swellable in an electrolytic solution and a non-swellable polymer to prepare a porous polymer web 15 made of a nanofiber 150 having a core-shell structure, Followed by a gelation heat treatment step.

The porous polymer web 15 is prepared by dissolving a mixture of a swellable polymer and a non-swellable polymer swellable in an organic electrolytic solution into a solvent to form a spinning solution, and then spinning a spinning solution to form a porous polymer web And calendering at a temperature not higher than the melting point of the polymer.

In this case, the spinning solution may contain a predetermined amount of inorganic particles to enhance the heat resistance.

When the mixture is composed of a swellable polymer and a non-swellable polymer and an inorganic particle, the swellable polymer and the non-swellable polymer have a weight ratio in the range of 4: 6 to 1: 9, preferably in the range of 5: 5 to 3: 7 It is preferable to mix them.

When the mixing ratio of the swelling polymer to the non-swelling polymer is less than 4: 6 by weight, the lithium ion conductivity increases but the swelling property of the swelling polymer becomes too large and acts as a separator physically isolating the positive electrode 1 and the negative electrode 3 The amount of the non-swellable polymer is decreased and the heat resistance and strength are lowered. That is, when the organic electrolytic solution is impregnated and then subjected to a gelation process, the swellable polymer shell 150a disposed on the outer side swells, and the non-swellable polymer core 150b disposed on the inner side swells uniformly over the entire polymer electrolyte membrane. The non-swellable polymer core 150b can not function as a separator, so that a short circuit between the positive electrode and the negative electrode can be prevented and safety can not be achieved.

When the mixing ratio of the swelling polymer to the non-swelling polymer is greater than 1: 9 by weight, the electrolyte can not be impregnated and swelling of the swelling polymer can occur. However, since the amount of the swollen polymer is small, And at the same time, the radioactivity is poor and a radiation trouble is generated.

The porous polymer web 15 has a core-shell structure when the molecular weight difference between the two polymers to be mixed is not less than the set value, when the mixed polymer is spun by mixing the swellable polymer and the non-swellable polymer . For example, when polyvinylidene fluoride (PVdF) having a molecular weight of 10,000 or less and polyacrylonitrile (PAN) having a molecular weight of 250,000 as a non-swelling polymer are mixed and spun as a swelling polymer, the radiated nanofibers 150 Swellable polymer having a large molecular weight is located in the core portion of the nanofiber 150 and a swellable polymer having a small molecular weight is located in the shell portion. As a result, the porous polymer web 15 of the present invention is composed of the core-shell structure nanofibers 150 surrounding the swellable polymer shell 150a outside the non-swellable polymer core 150b.

When the nanofiber 150 has a core-shell structure, the porous polymer web 15 is hydrophobic and exhibits hydrophobic properties due to the polyvinylidene fluoride (PVdF) disposed on the outer side. However, when the nanofiber 150 has a core- As the temperature increases, it can be confirmed that the hydrophilic material is changed to hydrophilic by polyacrylonitrile (PAN).

Therefore, in the present invention, it is preferable that the difference in molecular weight is 20 times or more when the swollen polymer and the non-swellable polymer are combined to form a mixed polymer, and it is preferable that the polymer is a polymer that can be prepared by nanofiber spinning after being dissolved in a solvent do.

In addition, the non-swellable polymer has a relatively high melting point because it has a larger molecular weight than the swellable polymer. In this case, the non-swelling polymer is preferably a resin having a melting point of 180 ° C or higher, and the swelling polymer is preferably a resin having a melting point of 150 ° C or lower, preferably 100-150 ° C.

In addition, the non-swellable polymer is a polymer that is relatively slow in swelling or does not swell in the solvent contained in the organic electrolytic solution due to the difference in molecular weight as compared with the swellable polymer.

In the present invention, the swellable polymer is required to be composed of a polymer having excellent conductivity so as to serve as a passage for transporting lithium ions oxidized or reduced at the cathode and the anode at the time of charging and discharging the battery.

The swellable polymer usable in the present invention is a resin which swells in an electrolytic solution and can be formed by ultrafine fibers by electrospinning. Examples of the swelling polymer include polyvinylidene fluoride (PVDF), polyvinylidene fluoride-co-hexafluoro Polypropylene), perfluoropolymers, polyvinyl chloride or polyvinylidene chloride and copolymers thereof, and polyethylene glycol derivatives including polyethylene glycol dialkyl ethers and polyethylene glycol dialkyl esters, poly (oxymethylene-oligo-oxy Polyvinyl acetate, poly (vinylpyrrolidone-vinyl acetate), polystyrene and polystyrene acrylonitrile copolymers, and polyacrylonitrile methyl methacrylate copolymers, including polyethylene oxide and polypropylene oxide, Containing polyacrylonitrile Polymethyl methacrylate, polymethyl methacrylate copolymer, and mixtures thereof.

In addition, the non-swellable polymer usable in the present invention can be dissolved in an organic solvent for electrospinning and is swollen more swollen than the swellable polymer due to the organic solvent contained in the organic electrolytic solution and does not swell, For example, polyacrylonitrile (PAN), polyamide, polyimide, polyamideimide, poly (meta-phenylene isophthalamide), polysulfone, polyether ketone, polyethylene terephthalate, Aromatic polyesters such as terephthalate, polyethylene naphthalate and the like, polyphosphazenes such as polytetrafluoroethylene, polydiphenoxaphospazene and poly {bis [2- (2-methoxyethoxy) Polyurethane copolymers including urethane and polyether urethanes, cellulose acetate, cellulose acetate butyrate Cellulose acetate propionate and the like can be used.

In the present invention, the production of the porous polymer web 15 is performed such that the porous polymer web 15 is formed on the outside of the non-swellable polymer core 150b with the nanofibers 150 of the core-shell structure surrounding the swellable polymer shell 150a. It is necessary to select the difference in the molecular weight when the mixed polymer is constituted by mixing the swellable polymer and the non-swellable polymer. Thus, it is desirable to combine the molecular weight difference between the swellable polymer and the non-swellable polymer such that the difference in molecular weight is at least 20-fold.

On the other hand, the porous polymer web 15 is obtained by spinning a spinning solution in which a swelling polymer and a non-swelling polymer are dissolved, and is preferably spinned using an air-electrospinning (AES) .

The spinning methods that can be used in the present invention include, in addition to air electrospinning (AES), electrospinning, electrospray, electroblown spinning, centrifugal electrospinning, -electrospinning) can be used.

For example, the porous polymer web 15 produced by air electrospinning (AES) is preferably 10 to 25 占 퐉, more preferably 10 to 15 占 퐉. If the thickness of the porous polymer web 15 is less than 10 mu m, the thickness of the non-swellable polymer core 150b remaining after the gelation of the swellable polymer shell 150a becomes too thin, Exceeds 25 m, the thickness of the swellable polymer shell 150a to be gelled also increases and the ionic conductivity drops.

The organic electrolytic solution embedded in the porous polymer web 15 of the polymer electrolyte 5 includes a non-aqueous organic solvent and a solute of a lithium salt.

The organic solvent is excellent in solubility in a swelling polymer and low in solubility in a non-swelling polymer, and the nanofiber 150 has a core-shell structure and a swellable polymer shell 150a is disposed outside the fiber Therefore, the organic solvent of the organic electrolytic solution embedded in the porous polymer web 15 mainly acts to gelify and plasticize the swellable polymer.

As the non-aqueous organic solvent, a carbonate, an ester, an ether or a ketone may be used. Examples of the carbonate include dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), methyl ethyl carbonate (MEC) Propylene carbonate (PC), butylene carbonate (BC) and the like can be used as the ester. Examples of the ester include butyrolactone (BL), decanolide, valerolactone, mevalonolactone Caprolactone, n-methyl acetate, n-ethyl acetate, n-propyl acetate and the like can be used. As the ether, dibutyl ether and the like can be used. As the ketone, polymethyl vinyl ketone However, the present invention is not limited to the kind of the non-aqueous organic solvent, and one or more kinds of them can be mixed and used.

In addition, the lithium salt acts as a source of lithium ions in a battery to enable operation of a basic lithium cell. Examples thereof include 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 ) (where x and y are natural numbers), and LiSO ₃ CF ₃ .

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 mixtures thereof.

When the mixture is composed of a swelling polymer, a non-swelling polymer and inorganic particles, the content of the inorganic particles added is preferably in the range of 10 to 25% by weight based on the total mixture when the size of the inorganic particles is between 10 and 100 nm Do. More preferably, the inorganic particles are contained in the range of 10 to 20 wt%, and the size is in the range of 15 to 25 nm.

If the content of the inorganic particles is less than 10% by weight based on the total amount of the mixture, the film shape can not be maintained and shrinkage occurs and the desired heat resistance characteristic can not be obtained. If the inorganic particle content exceeds 25% by weight, The solvent is volatilized rapidly and the film strength is lowered.

If the size of the inorganic particles is less than 10 nm, the volume becomes too large to handle. When the inorganic particle size is more than 100 nm, the inorganic particles are aggregated and exposed to the outside of the fiber.

On the other hand, as in the second embodiment shown in FIG. 2, the present invention can be applied to an ultra-thin inorganic polymer film layer (hereinafter, referred to as " 5a.

The structure of the second embodiment can be achieved, for example, by means of air electrospinning (AES) using a multi-hole radiation pack, in which the spinning nozzles are spaced apart along the direction of travel of the collector, After the first porous polymer web 15 is formed using the dissolved first spinning solution, a second polymer web layer of the thin film is then applied to the first porous polymer web 15 using a second spinning solution in which a single polymer is dissolved, To form first and second porous polymer web layers of a two-layer structure.

The polymer used for preparing the second spinning solution is a polymer resin which is swollen in an electrolytic solution and capable of conducting lithium ions and has excellent adhesiveness. Examples of the polymer resin include PVDF (polyvinylidene fluoride), PEO (Poly-Ethylen Oxide) , PMMA (polymethylmethacrylate), and TPU (thermoplastic polyurethane), and a polymer such as PVDF which is swellable and has excellent ion conductivity and excellent adhesiveness is preferable.

Thereafter, in a subsequent process, the first and second porous polymer web layers of the two-layer structure are arranged so that the second porous polymer web layer is opposed to the infrared lamp heater set at a temperature slightly lower than the melting point of the second porous polymer web layer The second porous polymer web layer is converted into the inorganic porous polymer film layer 5a to obtain a laminated structure of the first porous polymer web 15 and the inorganic porous polymer film layer 5a.

The inorganic polymer film layer 5a is preferably formed to a thickness of 2 to 5 占 퐉. When the inorganic polymer film layer 5a is less than 2 占 퐉, the function as an adhesive layer is weak. When the inorganic polymer film layer 5a is more than 5 占 퐉, Conductivity is lowered.

Hereinafter, a method of manufacturing a lithium ion polymer battery according to the present invention will be described with reference to FIGS. 3 to 6. FIG.

FIG. 3 is a process sectional view showing a process for producing a porous polymer web used as a polymer electrolyte according to the present invention, FIG. 4 is a process sectional view showing a sealing process of a porous polymer web used as an anode and a polymer electrolyte according to the present invention, Figure 6 is a schematic plan view of an electrode assembly assembled in accordance with the present invention. Figure 6 is a schematic cross-sectional view of an electrode assembly assembled in accordance with the present invention.

In the present invention, the porous polymer web 15 is first produced, for example, by air electrospinning (AES) as shown in Fig.

3, a high-voltage electrostatic force of 90 to 120 Kv is applied between the spinning nozzle 24 and the collector 26, from which the mixed spinning liquid having a sufficient viscosity is radiated. As a result, The nanofibers 150 radiated by jetting the air 24a for each spinneret 24 are supplied to the collector 26 and the porous polymer web 15 by spinning the ultrafine nanofibers 150 to form the porous polymer web 15. In this case, It catches what can not be caught and blown.

In the present invention, the mixed spinning solution is prepared by adding 40 to 90% by weight of a non-swelling polymer material and 10 to 60% by weight of a swelling polymer material to a two-component solvent or a one-component solvent. In this case, it is preferable to use a two-component solvent in which a solvent having a high boiling point (BP) and a low boiling point are mixed.

The air jet electrospinning apparatus used in the present invention includes a stirrer 22 that uses a pneumatic mixing motor 22a as a driving source so as to prevent phase separation until the non-swelling polymer material and the swellable polymer material are mixed with a solvent and is radiated, And a multi-hole nozzle pack (not shown) in which a plurality of spinning nozzles 24 to which a high voltage generator is connected are arranged in a matrix form. The mixed spinning liquid discharged from the mixing tank 21 to the plurality of spinning nozzles 24 connected to the quantitative pump (not shown) through the transfer tube 23 passes through the spinning nozzle 24 charged by the high voltage generator, The nanofibers 150 are accumulated on a grounded collector 26 of a conveyor type moving at a constant speed to form a porous polymer web 15.

In this case, in order to improve the workability of the subsequent process and the later-described anode sealing process, the transfer sheet 25a having a high tensile strength is transferred from the transfer roll 25 to the upper portion of the collector 26 of the air- So that the porous polymer web 15 is laminated on the transfer sheet 25a.

The transfer sheet 25a may be made of, for example, a polyolefin film such as a nonwoven fabric made of a polymer material which is not dissolved by a solvent contained in the paper or a mixed spinning solution, PE or PP, etc. . When the porous polymer web 15 alone is used, it is difficult to carry out the drying process, the calendering process, and the winding process while being conveyed at a high conveying speed because the tensile strength is low.

Furthermore, it is difficult to continuously carry out the subsequent sealing process with the positive electrode or the negative electrode after the porous polymer web 15 is manufactured at a high feed rate. However, when the above-mentioned transfer sheet 25a is used, sufficient tensile strength is provided, The processing speed can be greatly increased.

In addition, when only the porous polymer web 15 is used, a phenomenon of sticking to other objects due to static electricity occurs, which deteriorates workability. However, this problem can be solved when the transfer sheet 25a is used.

The transfer sheet 25a is subjected to roll pressing with an electrode as shown in Fig. 4, and then peeled and removed.

After the mixed spinning solution is prepared as described above, spinning is carried out by air-electrospinning (AES) using a multi-hole nozzle pack, spinning of microfine fibers having a diameter of 0.3 to 1.5 .mu.m occurs, And the porous polymer web 15 is fused in a three-dimensional network structure to form a stacked porous polymer web 15 on the transfer sheet 25a. The porous polymer web 15 made of microfine fibers is ultra-thin and light in weight, has a high volume-to-surface area ratio, and has a high porosity.

The porous polymer web 15 obtained as described above is then passed through a pre-air dry zone by the preheater 28 and the amount of solvent and moisture remaining on the surface of the porous polymer web 15 A calendering process using a hot pressing roller 29 is performed.

The pre-air dry zone by the preheater 28 is a process of applying air of 20 to 40 ° C to the web using a fan to remove the solvent remaining on the surface of the porous polymer web 15 By adjusting the amount of moisture, the porous polymer web 15 can be controlled to be bulky, thereby increasing the strength of the membrane and controlling the porosity.

In this case, when calendering is performed while the solvent is excessively volatilized, the porosity is increased but the strength of the web is weakened. On the contrary, when the volatilization of the solvent is reduced, the web is melted.

In the calendering process of the porous polymer web 15 following the above pre-drying process, it proceeds using a hot pressing roller 29, in which case the web is too bulky if the calendering temperature is too low (Bulky) and does not have rigidity. If it is too high, the web will melt and the pore will become clogged. In addition, thermocompression should be performed at a temperature at which the solvent remaining in the web can be completely volatilized. If the volatilization occurs too little, the web may melt.

In the present invention, calendering of the porous polymer web 15 is progressed by setting the heat press roller 29 at a temperature of 170 to 210 ° C and a pressure of 0 to 40 kgf / cm ² (excluding the self weight pressure of the pressing roller) The shrinkage of the liner line enables the stabilization of the porous polymer web 15 in actual use.

If the non-swelling polymeric material and the swellable polymeric material are, for example, PAN and PVdF, respectively, the calendering temperature and pressure are as follows:

Combination of PAN and PVdF: 170 to 210 ° C, 20 to 30 kgf / cm ²

When the web is calendered, a porous polymer web 15 having a thickness of 10 to 25 탆 is obtained.

In the present invention, if necessary, the porous polymer web 15 obtained after the calendering process described above is preferably dried using a secondary hot air dryer 30 having a temperature of 100 DEG C and an air velocity of 20 m / sec, And then wound on the winder 31 as a winding roll of the porous polymer web 15 in a state in which the transfer sheet 25a is disposed inside.

The resultant porous polymer web 15 has a molecular weight between two polymers mixed together as a combination of polyvinylidene fluoride (PVdF) and polyacrylonitrile (PAN) when the swellable polymer and non-swellable polymer are mixed and the mixed polymer is spun. By setting the difference to be equal to or greater than the set value, the emitted nanofibers 150 have a core-shell structure.

That is, the nanofibers 150 have polyvinylidene fluoride (PVdF) located at the core portion and polyvinylidene fluoride (PVdF) located at the shell portion. As a result, the porous polymer web 15 of the present invention is composed of the core-shell structure nanofibers 150 surrounding the swellable polymer shell 150a outside the non-swellable polymer core 150b.

Hereinafter, an electrode sealing process and a battery assembling process will be described with reference to FIGS. 4 and 7. FIG.

Referring to FIG. 4, any one of the positive electrode 1 and the negative electrode 3 can be sealed by an encapsulating process using two porous polymer webs 15. In the description of the embodiment, the encapsulation of the anode 1 will be described as an example.

First, the anode 1 is cast on both sides of the slurry including the cathode active material 11b and 11c so as to form a bi-cell (or a pull cell) in the strip-shaped cathode current collector 11a, The positive electrode strips 1n in which the positive electrode strips 1a-1d are sequentially formed are formed and wound on a reel using a winding machine (S11).

The cathode 3 is formed into a bi-cell (or pull-cell) structure in the same manner as the anode (S11), separated into individual unit cathode cells (S14) 3c).

The positive electrode strip 1n is subjected to blanking (i.e., punch molding) using a blanking equipment before winding on the reel or before the sealing process shown in Fig. 4 is started to remove the negative electrode strip 1n from the positive electrode strip 1n A plurality of unit anode cells 1a-1d are partially separated leaving a portion for forming the cathode terminal 11x (S12).

In the blanking step, the anode strips 1n are transported by a unit process length in accordance with the step-by-step transport of the anode strips 1n, blanking is performed for each unit process, A plurality of pores are formed and a space is formed between the unit positive electrode cells 1a-1d and the masking tape attaching regions formed on both side surfaces thereof, whereby each of the unit cell electrodes 1a-1d has a predetermined area such as a rectangle or a square It has a rectangular shape and is made to be interconnected.

Thereafter, a pair of porous polymer webs 15a and 15b are stacked on the transfer sheets 15c and 15d, respectively, with the porous polymer webs 15a and 15b stacked on the upper and lower portions of the positive electrode strip 1n, And the positive electrode strip 1n are successively passed through a roll pressing apparatus 33 composed of a pair of hot press rolls 33a and 33b and subjected to roll pressing with applying heat and pressure (S13).

In this case, the pair of porous polymer webs 15a and 15b have a strip shape having a width wider than the width of the positive electrode strip 1n by a predetermined length, as shown in Fig. It is preferable that the pair of porous polymer webs 15a and 15b are set equal to the width of the unit cathode cells 3a to 3c. In Fig. 6, 11x denotes a positive terminal and 13x denotes a negative terminal.

The transfer sheets 15c and 15d are peeled off from the porous polymer webs 15a and 15b as shown in FIG. 4 after being subjected to roll pressing for sealing the unit cell 1a-1d.

As a result, the pair of porous polymer webs 15a and 15b are sequentially sealed with a plurality of unit anode cells 1a-1d of the anode strip 1n by a roll-to-roll method The sealing can be performed, thereby achieving high productivity.

Thereafter, unit electrode cathodes 3a-3c are stacked between a plurality of unit anode cells 1a-1d sealed with a porous polymer web 15 as shown in FIG. 5 to form electrode assemblies 100, (S15). Taping is performed with the pressing band 101 made of a material having a high tensile strength, which does not swell in the organic solvent so as to surround the outside of the electrode assembly 100 (S16).

Generally, in an electrode assembly 100 in which a plurality of unit anode cells and unit cathode cells are stacked in a lithium ion polymer battery, there is a problem that the inside expands during charging and discharging, causing swelling and contraction in the direction of stacking of cells. If such an operation is repeated, the liquid electrolyte impregnated in the electrode is impregnated with the electrolyte to separate the electrode and the electrolyte. As a result, the interface resistance gradually increases, and the OCV (open circuit voltage) .

In the present invention, as described above, the outer surface of the electrode assembly 100 is taped to the thin film pressing band 101 made of non-swelling material, so that the expansion and contraction of the electrode assembly 100 during the charging / It is possible to prevent the deterioration of the interface between the electrolyte and the electrode, thereby suppressing the increase of the interface resistance and minimizing the decrease of the OCV (open circuit voltage).

Further, in the present invention, the positive electrode 1 and the negative electrode 3 are filled with a part of the swelling polymer so as to be continuous with the polymer electrolyte 5, so that the positive electrode 1 and the negative electrode 3, It can be adhered to the polymer electrolyte 5 to minimize the decrease in OCV (open circuit voltage).

As the pressing band 101, for example, an olefin-based film or a thin film ceramic such as PP / PE or PE / PP / PE nonwoven fabric or PET film available from Celgard can be used.

In the description of the embodiment shown in FIG. 5, the unit cell 100 is formed by stacking unit cathode cells 3a-3c between a plurality of unit anode cells 1a-1d by the Z folding method However, the present invention is not limited to this, and it is also possible to form the electrode assembly 100 by other methods and to tap the pressing band 101.

In this case, the pressing band 101 may be taped in a state where at least one plate for reinforcing strength is assembled to one side or both sides of the electrode assembly 100, if necessary.

For example, in place of the unit anode cells 1a-1d, a plurality of unit cathode cells 3a-3c are successively sealed with a pair of porous polymer webs 15a and 15b, The electrode assembly 100 of large capacity can be formed by laminating the unit positive electrode cells 1a-1d between the positive electrode plates 3a-3c.

The porous polymer webs 15a and 15b may be sandwiched between the anode 1 and the cathode 3 and integrated by a heat lamination process, and then laminated or rolled into a case.

The porous polymer webs 15a and 15b are adhered to one surface of the positive electrode 1 and the negative electrode 3 and then the positive electrode 1 and the negative electrode 3 having the porous polymer webs 15a and 15b formed on one surface thereof, Laminated, integrated by a heat lamination process, and then laminated or roll-rolled into a case.

Next, the electrode assembly 100 tapped with the pressing band 101 is embedded in a case (not shown) (S17), and an organic electrolytic solution is injected, followed by heat treatment so as to perform a gelling process (S18 and S19 ). In this case, the organic electrolytic solution to be injected is set to inject a proper amount of swelling polymer contained in the porous polymer web 15 by swelling 300 to 500%, so that gelation is carried out and the liquid organic solvent does not substantially remain.

In the present invention, since the porous polymer webs 15a and 15b disposed between the anode 1 and the cathode 3 are porous films having a three-dimensional pore structure, impregnation can be performed very quickly when an organic electrolyte is injected.

After the organic electrolytic solution is injected into the gelation step, the mixture is heated at a temperature in the range of 40 ° C to 120 ° C for 10 minutes to 600 minutes, followed by cooling.

Therefore, when the gelation is performed at a temperature higher than the melting point of the swelling polymer and lower than the melting point of the non-swelling polymer in the heat treatment process for gelation after injecting the organic electrolytic solution, the swelling polymer The shell 150a is plasticized and gelated, and the non-swellable polymer core 150b disposed inside is kept in a matrix shape as only a slight swelling occurs and the chain is not broken.

As a result, in the polymer electrolyte 5, the swellable polymer shell 150a which has been gelled forms an inorganic porous type gel electrolyte which does not substantially retain the liquid organic solvent as a whole, and the non-swellable polymer core 150b ) Maintains the shape without swelling of the electrolytic solution.

As a result, the swellable polymer shell 150a in the gel state exerts a function as a lithium ion conductor that carries lithium ions that are oxidized or reduced in the cathodes 3 and the positive electrodes 1 at the time of charging and discharging of the cells, and exhibits non-swelling The polymer core 150b acts as a separator physically isolating the positive electrode 1 and the negative electrode 3, thereby preventing a short circuit between the positive electrode and the negative electrode, thereby improving safety.

In this case, as a part of the swollen polymer swelled by the gelling process penetrates into the positive electrode 1 and the negative electrode 3, the interfacial resistance between the electrode and the polymer electrolyte 5 decreases, and at the same time, The electrolyte 5 can be made thinner.

In addition, the nanofiber 150 of the present invention having a core-shell structure has a structure in which a swellable polymer shell 150a is enclosed on the outside of the non-swellable polymer core 150b. After impregnating the organic electrolytic solution, The swellable polymer shell 150a disposed on the outer side becomes uniformly swollen, and battery characteristics can be uniformly expressed over the entire electrolyte membrane.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be construed as limited to the embodiments set forth herein. Various changes and modifications may be made by those skilled in the art.

The present invention is based on the idea that the nanofibers constituting the porous polymer web constitute a shell-core structure and that the swellable polymer shells disposed outside are gelled by the organic electrolytic solution. However, even if the non-swellable polymer core is arranged inside, The present invention can be applied to a secondary battery such as a lithium ion polymer battery having a polymer electrolyte. The present invention relates to a polymer electrolyte capable of simultaneously preventing safety and thinning by preventing a short circuit between the electrodes.

1: anode 1n: anode strip
1a-1d: unit positive electrode cell 3: negative electrode
3a-3c: unit cathode cell 5: polymer electrolyte
5a: Inorganic polymer film layer 11a: Positive electrode collector
11b: positive electrode active material 11x: positive electrode terminal
13a: anode current collector 13b: anode active material
13x: negative terminal 15-15b: porous polymer web
15c, 15d, 25a: transfer sheet 24: spinneret
24a: air 26: collector
28: Preheater 29: Compression roller
33: roll pressing apparatus 100: electrode assembly
101: compression band 150: nanofiber
150a: swellable polymer shell 150b: non-swellable polymer core

Claims (34)

A porous polymer web comprising nanofibers composed of a non-swellable polymer core comprising a swellable polymer shell made of a swellable polymer and a non-swellable polymer disposed outside the swellable polymer, the shell polymer having a shell-core structure along a longitudinal direction thereof; And
An organic electrolyte impregnated in the porous polymer web and having a lithium salt dissolved in a non-aqueous organic solvent,
Wherein the swellable polymer shell disposed outside the nanofibers is gelled by the organic electrolyte as the gelling process is performed, and the non-swellable polymer core disposed on the inside maintains the web shape. The method according to claim 1,
Wherein a part of the swellable polymer shell is permeated into the inside of the anode and the cathode disposed on both sides as the gelation is performed by the organic electrolytic solution. The polymer electrolyte of claim 1, wherein the porous polymer web is obtained by spinning a mixed polymer spinning solution comprising 40-90 wt% non-swellable polymer material and 10-60 wt% swellable polymer material. 4. The polymer electrolyte of claim 3, wherein the mixed polymer comprises 50-70 wt% non-swellable polymer material and 30-50 wt% swellable polymer material. The polymer electrolyte according to claim 1, wherein the difference between the molecular weight of the swellable polymer and that of the non-swellable polymer is 25 times or more. delete The polymer electrolyte according to claim 5, wherein the non-swelling polymer is a resin having a melting point of 180 ° C or higher. The polymer electrolyte of claim 1, wherein the porous polymer web comprises inorganic particles in the range of 10 to 25 weight percent. The organic electroluminescent device according to claim 1, further comprising an inorganic hollow polymer film layer which is laminated on one side of the porous polymer web and is made of a polymer which swells in the organic electrolytic solution and is excellent in adhesion to an electrode, Lt; / RTI > The polymer electrolyte according to claim 9, wherein the thickness of the porous polymer web is set in the range of 10 to 25 mu m, and the thickness of the inorganic porous polymer film layer is set in the range of 2 to 5 mu m. A positive electrode and a negative electrode capable of intercalating and deintercalating lithium, and a polymer electrolyte disposed between the positive electrode and the negative electrode,
The polymer electrolyte may contain,
A porous polymer web comprising nanofibers composed of a non-swellable polymer core comprising a swellable polymer shell made of a swellable polymer and a non-swellable polymer disposed outside the swellable polymer, the shell polymer having a shell-core structure along a longitudinal direction thereof; And
An organic electrolyte impregnated in the porous polymer web and having a lithium salt dissolved in a non-aqueous organic solvent,
Wherein the swellable polymer shell disposed outside the nanofibers is gelled by the organic electrolytic solution as the gelling process is performed, and the non-swellable polymer core disposed on the inner side maintains a web shape. 12. The lithium secondary battery according to claim 11, wherein a portion of the swellable polymer shell is infiltrated into the positive and negative electrodes disposed on both sides as the gelation is performed by the organic electrolytic solution. The lithium secondary battery according to claim 11, wherein the anode or the cathode is sealed by a pair of the porous polymer webs. delete 12. The method of claim 11,
Wherein the positive electrode and the negative electrode are composed of a plurality of unit electrode cells stacked alternately and separated by the polymer electrolyte. 16. The method of claim 15,
Further comprising a compression band for blocking expansion of a plurality of anode and cathode unit electrode cells separated and stacked by the polymer electrolyte in the stacking direction. The lithium secondary battery according to any one of claims 11 to 13, 15, and 16, wherein each of the anode and the cathode is a bi-cell structure in which an electrode active material is formed on both surfaces of the electrode current collector. 12. The method of claim 11,
Wherein the positive electrode or the negative electrode is encapsulated with the polymer electrolyte in a plurality of unit electrode cells obtained by subjecting the electrode active material to continuous blanking to electrode strips formed on both sides of the strip- battery. A positive electrode and a negative electrode capable of intercalating and deintercalating lithium, and
A lithium secondary battery comprising the polymer electrolyte according to any one of claims 1 to 5 and 7 to 10. Dissolving a non-swellable polymer and a swellable polymer in a solvent to form a mixed polymer spinning solution;
A swellable polymer shell comprising a swellable polymer swelling the organic electrolytic solution outside the non-swellable polymer core made of a non-swellable polymer by spinning the mixed polymer spinning solution, and having a nanocomposite structure having a shell- Forming a polymer web;
Forming an electrode assembly in which the porous polymer web is inserted between an anode and a cathode, the electrode assembly comprising a plurality of unit electrode cells;
Inserting the electrode assembly into a case and injecting an organic electrolyte; And
Performing a gelling heat treatment to swell the swellable polymer shell disposed outside the nanofibers with an organic electrolytic solution,
Wherein the non-swellable polymer core disposed inside the nanofibers maintains a web shape. 21. The method of claim 20, wherein the porous polymer web comprises 40-90 wt% non-swellable polymer material and 10-60 wt% swellable polymer material. 21. The method of claim 20,
Further comprising taping the electrode assembly with a compression band to block expansion of the plurality of unit positive and negative electrode cells in the stacking direction. 21. The method of claim 20, wherein forming the electrode assembly
Forming an electrode strip by coating an electrode active material layer on at least one side of the strip-shaped electrode current collector of the positive electrode and the negative electrode;
Performing sequential blanking while transferring the electrode strip in a step-by-step manner to partially separate and form a plurality of first unit electrode cells from the electrode strip;
Sealing the plurality of first unit electrode cells with a pair of porous polymer webs on both sides while continuously transporting the plurality of first unit electrode cells; And
And inserting and stacking a plurality of second unit electrode cells of the other one of the positive and negative electrodes between the plurality of sealed first unit electrode cells. delete delete delete delete delete delete A plurality of unit anode cells and a plurality of unit cathode cells are alternately laminated while alternately stacking a plurality of unit anode cells and a plurality of unit cathode cells using a pair of porous polymer webs having nanofibers composed of a non-swellable polymer core and a core-shell structure of a swellable polymer shell, ;
Taping the electrode assembly with a compression band;
Inserting the electrode assembly into a case and injecting an organic electrolyte; And
And performing a gelling heat treatment,
The swellable polymer shell disposed outside the nanofiber is gelled by the organic electrolytic solution and the non-swellable polymer core disposed on the inner side maintains a web shape as the step of performing the gelation heat treatment is performed A method of manufacturing a lithium secondary battery. 31. The method of claim 30, wherein the pair of porous polymer webs
Dissolving a non-swellable polymer and a swellable polymer in a solvent to form a mixed polymer spinning solution; And
And spinning the mixed polymer spinning solution to form a porous polymer web having nanofibers each having a shell-core structure along a longitudinal direction,
Wherein the nanofibers each have a non-swellable polymer core formed of a non-swellable polymer core, and a swellable polymer shell formed of a swellable polymer that swells the organic electrolyte solution. 32. The method of claim 31,
In the case of performing the gelation heat treatment, the swellable polymer shell disposed outside the nanofibers is swelled by the organic electrolytic solution, and the non-swellable polymer core disposed inside the nanofibers maintains a web shape Gt; < tb >< / TABLE > 32. The method of claim 31, wherein the mixed polymer spinning solution comprises 40-90 wt% non-swellable polymer material and 10-60 wt% swellable polymer material. 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 polymer webs comprising nanofibers composed of a non-swellable polymer and a swellable polymer;
A pressing band for taping the outer periphery of the electrode assembly; And
An electrode assembly that is taped with the compression band and includes an organic electrolyte injected case,
Wherein the swellable polymer shell disposed outside the nanofibers is gelled by the organic electrolytic solution as the gelling process is performed, and the non-swellable polymer core disposed on the inner side maintains a web shape.

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