KR100858795B1 - Lithium polymer battery containing seperator chemically bonded to polymer electrolyte and manufacturing method thereof - Google Patents

Abstract

In a lithium battery having a cathode and an anode capable of absorbing and discharging lithium ions, a separator interposed therebetween, and a polymer electrolyte, the separator is chemically bonded to the polymer electrolyte as a polyolefin separator or a fluorinated polyolefin separator. In the lithium battery of the present invention, since the radicals formed by the peroxide groups formed on the surface of the porous separator and inside the pores are cleaved by actinic radiation irradiation, the radicals also participate in thermal polymerization of the monomers in the composition for forming a polymer electrolyte. As a result, the polymer electrolyte and the separator are chemically bonded to reduce the interfacial resistance between them, and the adhesion between the electrode and the separator is also increased, thereby improving battery performance, reducing swelling at high temperatures, reducing electrolyte leakage problems, and improving safety. Having features becoming .

Description

Lithium polymer battery containing a separator chemically bonded to a polymer electrolyte and a method for manufacturing the same

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows typically the process of irradiating the surface of a separator with actinic radiation.

FIG. 2 is a diagram schematically illustrating a situation in which a peroxide group is formed on the surface of a separator by the actinic radiation.

3 is a view showing radicals generated on the surface of a separator during thermal polymerization to form a polymer electrolyte.

<Description of Major Symbols in Drawing>

1: Separator 3: actinic radiation

The present invention relates to a lithium polymer battery and a method of manufacturing the same, and more particularly, to a lithium polymer battery having improved battery performance by reducing the interfacial resistance between the separator and the polymer electrolyte by including a separator chemically bonded to the polymer electrolyte. It relates to a manufacturing method.

As the spread of portable electronic information devices such as notebook computers, camcorders, and wireless communication devices such as mobile phones is increasing, there is an increasing demand for miniaturization and weight reduction of rechargeable rechargeable batteries used as their power sources. .

Among the secondary batteries developed so far, nickel cadmium batteries, nickel hydrogen batteries, and lithium batteries are used. Among them, lithium batteries are attracting the most attention as next generation power sources due to their excellent characteristics such as long life and high capacity.

It was common to use a liquid electrolyte as an electrolyte of a conventional lithium secondary battery. However, when the liquid electrolyte is used as the electrolyte, the device is damaged due to the leakage of the electrolyte, the inside of the battery is dried due to the volatilization of the solvent, and there is a problem in that a short is generated between the electrodes. In order to solve this problem, a method of using a solid electrolyte instead of a liquid electrolyte has been proposed.

Solid electrolytes are generally researched in a great deal of interest because there is no fear of leakage of electrolytes, and thus, they are excellent in safety and easy to process. In particular, since it is known that polymer electrolytes exhibit high ionic conductivity at room temperature, they have been promising them as electrolyte materials for various electrochemical cells, and research into polymer electrolytes having excellent ionic conductivity at room temperature is particularly active. It is done.

Such polymer electrolytes include a pure polymer electrolyte in which a lithium salt is kept in a polymer and a polymer gel electrolyte in which an organic electrolyte is swollen in a polymer. The polymer gel electrolyte is a means of non-fluidizing the organic solvent electrolyte, and the gelation of the polymer was conceived.

However, as a material for forming a polymer matrix of a polymer electrolyte, a curable polymer based on polyethylene glycol di (meth) acrylate, poly (acrylonitrile), poly (ethylene oxide), poly (methyl methacrylate), and combinations thereof (combination) and the like. Specific examples of such a polymer electrolyte are as follows.

U.S. Patent 4,908,283 discloses a polymer electrolyte made by curing a composition composed of acryloyl-denatured polyalkylene oxide, and U.S. Patent 4,792,504 discloses polyethylene glycol dimethacrylate / polyethylene oxide. A polymer electrolyte composed of In addition, US Patent No. 4,830,939 discloses a method for preparing a plasticized polymer electrolyte by mixing polyethylene glycol dimethacrylate with a liquid electrolyte and then curing it.

As a method of forming a polymer electrolyte in such a lithium polymer battery, any one of the following three methods (1) to (3) is generally used.

(1) A polymer electrolyte layer impregnated with a lithium salt electrolyte by first applying a composition for forming a polymer electrolyte containing a lithium salt organic electrolyte on a cathode and / or anode prepared by a conventional method, and then polymerizing the monomers in the composition. This laminated cathode and anode are manufactured. Subsequently, a separator is inserted between the cathode and the anode thus prepared, and the separator is wound in a jelly roll manner to form a battery assembly, or a plurality of these are stacked to complete a battery assembly having a bicell structure. The battery assembly is then placed in a battery case and sealed to complete the lithium polymer battery.

(2) A separator is inserted between a cathode and an anode manufactured by a conventional method and wound up in a jelly roll manner to form a battery assembly, or a plurality of them are stacked to complete a battery assembly having a bicell structure. This battery assembly is then placed in a battery case, and a composition for forming a polymer electrolyte containing a lithium salt organic electrolyte is injected into the battery case. Subsequently, the battery case is sealed and heated to a predetermined temperature to polymerize the monomer in the composition to complete the lithium polymer battery.

(3) The separator impregnated with a lithium salt electrolyte is manufactured by apply | coating and then polymerizing the composition for polymer electrolyte formation containing a lithium salt organic electrolyte on both surfaces of a separator. Subsequently, a separator prepared above is inserted between a conventional cathode and an anode, and these are wound in a jellyroll manner to form a battery assembly, or a plurality of them are stacked to complete a battery assembly having a bicell structure. The battery assembly is then placed in a battery case and sealed to complete a lithium polymer battery.

However, the conventional lithium polymer battery manufactured by the above method has the following problems.

(1) First, the separator and the polymer electrolyte are only bonded to each other, and there is no chemical bond between them. Therefore, the interfacial resistance between the separator and the polymer electrolyte is large, resulting in a decrease in the ion conductivity of lithium ions resulting in poor battery performance. There is a problem.

(2) Second, due to the poor adhesion between the electrodes (cathode and anode) and the polymer electrolyte, the organic electrolyte solution impregnated in the polymer matrix was leaked, resulting in reduced battery performance and low adhesion between the electrode and the separator at high temperature. Due to this, the swelling phenomenon is increased and battery safety is poor.

Accordingly, an object of the present invention is to provide a lithium polymer battery having improved battery performance by chemically bonding a polymer electrolyte and a separator to solve the above problems.

Another object of the present invention is to provide a method for manufacturing the lithium polymer battery.

In order to achieve the above technical problem, the present invention provides a lithium battery having a cathode and an anode capable of absorbing and discharging lithium ions, a separator interposed therebetween, and a polymer electrolyte,

The separator provides a lithium battery chemically bonded with the polymer electrolyte as a polyolefin separator or a fluorinated polyolefin separator.

In the lithium battery according to the present invention, the polymer electrolyte is (a) 0.1 to 90% by weight of a compound represented by the following formula (1), a compound represented by the following formula (2) or a mixture thereof; (b) 0.1 to 90% by weight of a compound represented by Formula 3 below; And (c) 9.8 to 99.8% by weight of a non-aqueous organic solvent containing 0.5 to 2.0 mol / l (M) of lithium salt.                     

CH (R1) = C (R2) -C (= O) O-R3-N (R4) (R5)

CH (R1) = C (R2) -C (= O) O-R3-CN

Z-[-Y-X-C (R2) = CH (R1)] n

In Formulas 1, 2 and 3, R1 and R2 are each independently selected from hydrogen, C1 to C10 alkyl group, C1 to C10 fluorinated alkyl group, C1 to C10 aryl group, and C1 to C10 fluorinated aryl group One,

R3 is any one selected from the following groups,

R4 and R5 may be any one selected from the following groups, and R4 and R5 may have the same structure.

X is any one selected from the following group, wherein R6 represents hydrogen, methyl group, ethyl group, propyl group or butyl group,

Y is any one selected from the following group, where m = an integer from 0 to 10:

n is an integer of 1-6, and Z has the following structure according to each n value.

when n = 1, Z is H or an alkyl group of C1-C12                     

when n = 2, Z is any one selected from

when n = 3, Z is any one selected from

when n = 4, Z is any one selected from

When n = 5 or 6, Z is any one selected from the following group.

In the lithium battery according to the present invention, the composition is any one or more polymerization selected from the group consisting of benzophenone compounds, diacyl peroxide compounds, azo compounds, peroxy ester compounds, and peroxy carbonate compounds It is preferable to further include 0.1 to 10% by weight of the initiator based on the total amount of the compounds represented by the formula (1), (2) and (3).

In the lithium battery according to the present invention, the benzophenone-based compound is preferably benzophenone or substituted benzophenone.

In the lithium battery according to the present invention, the diacyl peroxide compound is preferably benzoyl peroxide, acetyl peroxide or lauroyl peroxide.

In the lithium battery according to the present invention, the azo compound is azobisisobutyronitrile (AIBN), azobis (2,4-dimethyl valeronitrile) (azobis (2,4-dimethyl valeronitrile)), or azo It is preferable that it is bis (cyclohexanecarbonitrile).

In the lithium battery according to the present invention, the peroxy ester compound is preferably t-butyl peroxy ester (t-butyl peroxy ester) or t-amyl peroxybenzoate (t-amyl peroxybenzoate).

In the lithium battery according to the present invention, the peroxy carbonate-based compound is t-butyl peroxy isopropyl carbonate (t-butyl peroxy isopropyl carbonate) or t-butyl peroxy 2-ethylhexyl carbonate (t-butyl peroxy 2- ethylhexyl carbonate).

In the lithium battery according to the present invention, the polyolefin separator or fluorinated polyolefin separator is a polyethylene separator, a polypropylene separator, a polyvinylidene fluoride separator, a vinylidene fluoride and hexafluoropropylene copolymer separator, a polyethylene / polypropylene It is preferable that it is a 2-layer separator of 3, a 3 layer separator of polypropylene / polyethylene / polypropylene, or a 3 layer separator of polyethylene / polypropylene / polyethylene.

In the lithium battery according to the present invention, the lithium salt is LiPF ₆ , LiClO ₄ , LiBF ₄ , LiBF ₆ , LiAsF ₆ , and LiN (SO ₂ CF ₃ ) ₂ , LiN (SO ₂ C ₂ F ₅ ) ₂ and purple It is preferably at least one selected from the group consisting of lithium salt compounds of fluorosulfonate.

In the lithium battery according to the present invention, the organic solvent is ethylene carbonate, propylene carbonate, dimethyl carbonate, methylethyl carbonate, diethyl carbonate, vinylene carbonate, triglyme, tetraglyme, fluorobenzene, difluorobenzene , γ-butyrolactone is preferably at least one selected from the group consisting of.

In the lithium battery according to the present invention, the chemical bond is preferably an ether bond.

The present invention, in order to achieve the above other technical problem                     

Providing a cathode, anode and polyolefin-based or fluorinated polyolefin-based separator;

Irradiating the surface of the separator with actinic radiation to form peroxide groups on the surface of the separator;

Manufacturing a unit cell assembly by interposing the separator between the cathode and the anode, and placing the battery into a battery case;

The composition according to the present invention (composition according to any one of claims 2 to 11) is placed inside the battery case, sealed, and heated to generate radicals generated by cleavage of the peroxide group. It provides a method for producing a lithium battery comprising the step of polymerizing the compound of Formulas 1 to 3 to form a polymer electrolyte chemically bonded to the separator.

In the method of manufacturing a lithium battery according to the present invention, the actinic ray is preferably ultraviolet (UV), electron beam, γ-ray, glow discharge or plasma.

In the method of manufacturing a lithium battery according to the present invention, the peroxide group may be a hydroperoxy group (-OOH).

In the method of manufacturing a lithium battery according to the present invention, the thermal polymerization temperature is preferably 20 to 100 ° C.

In the method of manufacturing a lithium battery according to the present invention, when using ultraviolet (UV), it is preferable to form peroxide groups on the surface of the separator using light having a wavelength of 200 to 400 nm.

In the lithium polymer battery of the present invention, radicals generated by cleavage of peroxide groups formed on the surface of the porous separator and in the pores also participate in thermal polymerization of monomers in the composition for forming a polymer electrolyte. In addition, the interfacial resistance between them is reduced, as well as the adhesion between the electrode and the separator is increased, thereby improving battery performance, reducing swelling at high temperatures, reducing electrolyte leakage problems, and improving safety.

Hereinafter, a lithium polymer battery according to the present invention will be described in detail.

The lithium polymer battery according to the present invention is characterized in that the separator interposed between the cathode and the anode is chemically bonded to the polymer electrolyte.

The separator is a polyolefin separator or a fluorinated polyolefin separator, for example, a polyethylene separator, a polypropylene separator, a polyvinylidene fluoride separator, a vinylidene fluoride and hexafluoropropylene copolymer separator, and a polyethylene / polypropylene layer. It is preferable that it is a separator, the three layer separator of polypropylene / polyethylene / polypropylene, or the three layer separator of polyethylene / polypropylene / polyethylene.

The polymer electrolyte may include (a) 0.1 to 90% by weight of a compound represented by Chemical Formula 1, a compound represented by Chemical Formula 2, or a mixture thereof; (b) 0.1 to 90% by weight of the compound represented by Formula 3; And (c) 9.8 to 99.8 wt% of a non-aqueous organic solvent containing 0.5 to 2.0 moles of lithium salt.                     

The chemical bond between the separator and the polymer electrolyte, which is a feature of the lithium polymer battery of the present invention, is generated by cleavage of peroxide groups formed on the surface and inside of the pore of the polyolefin-based polymer film or fluorinated polyolefin-based polymer film constituting the porous separator. Radicals are formed by initiating radical polymerization of the monomers represented by Formulas 1 to 3 contained in the composition in a polymerization step for forming the polymer electrolyte forming composition. Accordingly, the polyolefin-based or fluorinated polyolefin-based separator and the polymer electrolyte are connected by chemical bonds such as ether bonds formed by the polymerization to reduce the interfacial resistance therebetween.

Hereinafter, the manufacturing method of the lithium polymer battery of the present invention will be described in detail, whereby the lithium polymer battery of the present invention will be described in more detail.

First, the method of preparing the composition for forming a polymer electrolyte used in the present invention will be described.

The compound represented by the formula (2), the compound represented by the formula (3) or a mixture thereof is mixed with the compound represented by the formula (1) in the ratio as described above. The ratio as described above is selected as the optimum ratio in consideration of the electrochemical stability, battery performance and the like of the lithium polymer battery to be produced.

Such a composition may include any one or more polymerization initiators selected from the group consisting of benzophenone compounds, diacyl peroxide compounds, azo compounds, peroxy ester compounds, and peroxy carbonate compounds. 0.1 to 10% by weight based on the total amount of the compound represented by.                     

In preparing the battery by injecting the composition into the battery, sealing and thermally polymerizing, in the selection of the polymerization initiator, it is preferable to use a peroxide compound rather than an azo compound. This is because in the case of azo compounds, inert nitrogen gas is generated during thermal polymerization, which impedes the generation of a uniform polymer electrolyte, thereby providing a cause of deterioration of battery performance. However, in the case of peroxide compounds, peroxy carbonate compounds, peroxy ester compounds, This is because the diacyl peroxide compound may generate a uniform polymer electrolyte by generating CO 2 gas having good solubility in the electrolyte during thermal polymerization. Moreover, since CO2 is known to form a stable film on a negative electrode and improve battery performance, it is preferable to use a peroxide compound as a thermal polymerization initiator.

In the case of the above-mentioned peroxide compound, it is preferable to add an activator for lowering the temperature since the effective initiation temperature of many compounds except some is not more than 100 ° C, and it is well known as a tertiary amine. Compound. An initiator system consisting of a peroxide compound and a tertiary amine compound is known as a redox initiation system and has been widely used in self-curing acrylic resins.

In the case of the compound represented by Formula 1, it has not only an unsaturated double bond which causes a polymerization reaction but also has a tertiary amine group to act as an activator as well as a monomer of the reaction in the polymerization reaction. Therefore, when using the compound represented by the formula (1), there is an advantage that can be used a polymerization initiator that can operate in a wide temperature range. An advantage of the compound represented by Formula 1 over general tertiary amine compounds is that it is a component of the polymer matrix produced by polymerization. In general, tertiary amine compounds are present in an independent state rather than as a component of the polymer matrix after the reaction, which may cause electrochemical decomposition during charging and discharging of the battery, thereby degrading battery performance. Since it is in a stable state for decomposition reaction, battery performance can be prevented.

Then, as described above, a non-aqueous organic solvent containing 0.5 to 2.0 mol / l (M) of lithium salt is further added at the above-mentioned ratio, stirred and mixed uniformly.

Lithium salt and organic solvent constituting the electrolytic solution of the present invention can be used without particular limitation as long as it is known in the art to which the present invention belongs, Lithium salts LiPF ₆ , LiClO ₄ , LiBF ₄ , LiBF ₆ , LiAsF ₆ , and LiN It is preferably at least one selected from the group consisting of (SO ₂ CF ₃ ) ₂ , LiN (SO ₂ C ₂ F ₅ ) ₂ and a lithium salt compound of perfluorosulfonate, and the organic solvent is ethylene carbonate, propylene carbonate, dimethyl It is preferably at least one selected from the group consisting of carbonate, methylethyl carbonate, diethyl carbonate, vinylene carbonate, triglyme, tetraglyme, fluorobenzene, difluorobenzene and γ-butyrolactone.

Next, a method of manufacturing the lithium polymer battery of the present invention using the above-described composition for forming a polymer electrolyte will be described.

First, an electrode active material layer is formed on a current collector using an electrode active material composition comprising an electrode active material, a binder, a conductive agent, and a solvent. In this case, the electrode active material layer may be formed by directly coating the electrode active material composition on the current collector, or by coating and drying the electrode active material composition on a separate support, and then peeling the film from the support. There is a way to laminate. Herein, the support may be used as long as it can support the active material layer, and specific examples thereof include a mylar film, a polyethylene terephthalate (PET) film, and the like.

The electrode active material used in the present invention is a lithium transition metal oxide such as LiCoO _{2 in} the case of a cathode, carbonaceous materials such as carbon, graphite, etc. are used for the anode, carbon black, etc. are used as the conductive agent. .

Herein, the content of the conductive agent is preferably 1 to 20 parts by weight based on 100 parts by weight of the electrode active material.

As the binder, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer (VDF / HFP copolymer), polyacrylonitrile, polymethyl methacrylate and mixtures thereof are used, and the content thereof is an electrode. It is preferably 1 to 30 parts by weight based on 100 parts by weight of the active material.

The solvent may be used as long as it is used in a conventional lithium secondary battery, and specific examples thereof include acetone, N-methylpyrrolidone (NMP), acetonitrile, tetrahydrofuran and the like.

In this manner, apart from the preparation of the cathode and the anode, the surface of the above-described polyolefin separator or fluorinated polyolefin separator is irradiated with actinic radiation to form peroxide groups on the surface of the separator.                     

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows typically the process of irradiating the surface of a separator with actinic radiation.

Referring to FIG. 1, both sides of the separator 1 are irradiated with actinic rays 3 for 5 seconds to 1 minute. In this case, ultraviolet rays (UV), electron beams, γ-rays, glow discharges, or plasma may be used as the actinic rays, but it is preferable to use ultraviolet rays in terms of economics, safety, and ease of use. When using ultraviolet (UV), it is preferable to use light having a wavelength of 200 ~ 400nm.

FIG. 2 is a diagram schematically showing a situation in which a peroxide group is formed on the surface of the separator 1 by the actinic radiation.

Referring to FIG. 2, peroxide groups, more specifically hydroperoxy groups (—O—OH), are formed on the surface of the separator 1.

Subsequently, a separator having a peroxide group formed on the surface is inserted between the prepared cathode and the anode to prepare a battery assembly, and then placed in a battery case. Subsequently, the polymer electrolyte-forming composition according to the present invention is put into the battery case and sealed, and then heated to 20 to 100 ° C. In this case, the monomers of Chemical Formulas 1 to 5 in the polymer electrolyte composition are thermally polymerized. In this case, the above-described polymerization initiator may be included or included. When the polymerization initiator is included, a radical derived from a polymerization initiator generated while generating a gas such as CO ₂ or N ₂ from the polymerization initiator initiates polymerization of the monomers. To polymerize to form a polymer matrix of the polymer electrolyte, thereby providing a medium on which the lithium salt organic electrolyte can be impregnated.

However, in the thermal polymerization, peroxide groups formed on the surface of the separator are cleaved to generate polymer radicals which form part of the chemical structure of the polyolefin-based or fluorinated polyolefin-based polymer forming the separator, unlike the low-molecular radicals derived from the polymerization initiator.

3 is a view showing radicals on the surface of the separator thus generated. Referring to FIG. 3, it can be seen that oxygen radicals forming a part of the chemical structure of the polymer are formed on the surface of the separator. In addition, although not shown in FIG. 3, polymer radicals are similarly generated in the pores of the separator by the action of the actinic rays.

However, according to PJ Flory's theory, these polymer radicals can also initiate polymerization of monomers with the same degree of activity as low molecular radicals, such as, for example, phenyl radicals, derived from polymerization initiators, resulting in separators and polymers. More specifically, the electrolyte is chemically bonded to the separator and the polymer matrix in the polymer electrolyte through an ether bond. Therefore, since the separator and the polymer electrolyte are connected in a single phase rather than two phases, the interfacial resistance between them can be greatly reduced to improve the ion conductivity of lithium ions. Therefore, the lithium polymer battery of the present invention can improve battery performance, such as life characteristics, low temperature discharge characteristics.

In addition, since the surface of the separator is ionized by actinic rays to increase wettability, the effect of increasing the adhesion between the separator and the electrodes (cathode and anode) is also exerted. Therefore, in the lithium polymer battery according to the present invention, leakage of the organic electrolyte is reduced and swelling at a high temperature is reduced, thereby preventing deterioration of safety and reliability of the battery.

Hereinafter, a method of manufacturing the lithium polymer battery of the present invention will be described in more detail with reference to the following examples, and those skilled in the art may devise various modifications within the scope of the present invention. It is of course not limited by example.

 Example 1

15 g of polyvinylidene fluoride was added to 600 ml of N-methyl pyrrolidone and mixed for 2 hours to dissolve. 470 g of LiCoO ₂ and 15 g of carbon black (Super-P) were added to the mixture, which was then ball milled for 5 hours to form a cathode active material composition.

The cathode active material composition was coated and dried on an aluminum thin film having a thickness of 147 μm and a width of 4.9 cm using a doctor blade having a 320 μm gap to form a cathode electrode plate.

Meanwhile, the anode electrode plate was manufactured according to the following procedure.

30 g of polyvinylidene fluoride was added to 600 ml of N-methyl pyrrolidone and mixed for 2 hours to dissolve. 470 g of mesocarbon fiber (MCF) was added to the mixture, followed by ball milling for 5 hours to form an anode active material composition.

The anode active material composition was coated and dried on a copper thin film having a thickness of 178 µm and a width of 5.1 cm using a doctor blade having a gap of 420 µm to form an anode electrode plate.

Separately, a three-layer separator made of propylene / polyethylene / polypropylene (Celgard) having a thickness of 25 μm and a width of 5.35 cm was used as a separator. Both sides of the separator were exposed to ultraviolet rays (λ max = 360 nm) in air. Irradiation for 30 seconds produced hydroperoxy groups on the surface.

A battery assembly was made by interposing the activated three-layer separator between the cathode electrode plate and the anode electrode plate, and winding it in a jellyroll manner. This cell assembly was then placed in an aluminum pouch.

Ethylene carbonate (EC) / diethylene carbonate in which 2 g of dimethylaminoethyl methacrylate, 3 g of diethylene glycol monoethyl ether methacrylate, 1 g of polyethylene glycol dimethacrylate, 0.06 g of AIBN initiator, and LiPF6 of 1.3 M concentration were dissolved 15 g of a mixed organic solvent of (DEC) / propylene carbonate (EC: DEC: PC is 41:49:10) was mixed to prepare a composition for forming a polymer electrolyte. 3 g of this composition was injected into the pouch battery prepared above and then sealed. This resultant was then left for 4 hours in an oven controlled at 75 ° C. to produce a lithium polymer battery.

 Example 2

A lithium polymer battery was completed in the same manner as in Example 1 except that the electron beam was used to generate active radicals in the separator.

 Example 3

A lithium polymer battery was completed in the same manner as in Example 1, except that glow discharge was used to generate active radicals in the separator.

 Example 4

A lithium polymer battery was completed in the same manner as in Example 1 except that gamma rays emitted from a Co ⁶⁰ source were used to generate active radicals in the separator.

 Example 5

A lithium polymer battery was completed in the same manner as in Example 1 except that 2-cyanoethyl acrylate was used instead of dimethylaminoethyl methacrylate.

 Example 6

A lithium polymer battery was completed in the same manner as in Example 2, except that 2-cyanoethyl acrylate was used instead of dimethylaminoethyl methacrylate.

 Example 7

A lithium polymer battery was completed in the same manner as in Example 3, except that 2-cyanoethyl acrylate was used instead of dimethylaminoethyl methacrylate.

 Example 8

A lithium polymer battery was completed in the same manner as in Example 4, except that 2-cyanoethyl acrylate was used instead of dimethylaminoethyl methacrylate.

 Example 9

A lithium polymer battery was completed in the same manner as in Example 1 except that AIBN was not used.

 Example 10

A lithium polymer battery was completed in the same manner as in Example 2 except that AIBN was not used.

 Example 11

A lithium polymer battery was completed in the same manner as in Example 3 except that AIBN was not used.

 Example 12

A lithium polymer battery was completed in the same manner as in Example 4 except that AIBN was not used.

 Comparative Example 1

A lithium polymer battery was completed in the same manner as in Example 1 except that the three-layer separator of propylene / polyethylene / polypropylene (Celgard) was used as it was without activation treatment with ultraviolet rays.

As a result of evaluating the low-temperature discharge characteristics, the life characteristics, and the high temperature swelling characteristics of the lithium polymer batteries of Examples 1 to 12 and Comparative Example 1, the batteries of Examples 1 to 12 increased the adhesion between the polymer electrolyte and the separator. Due to the decrease in interfacial resistance, the low-temperature discharge and lifetime characteristics were superior to those of Comparative Example 1, and the high-temperature swelling characteristics were also excellent.

As described above, in the lithium polymer battery of the present invention, since the separator and the polymer electrolyte are connected in a single phase, the interfacial resistance between them is greatly reduced, thereby improving the ion conductivity of lithium ions. Therefore, the lithium polymer battery of the present invention can improve battery performance, such as life characteristics, low temperature discharge characteristics.

Moreover, since the surface of a separator is ionized by actinic radiation and wettability increases, the effect that the adhesive force of a separator and an electrode also increases is exhibited. Therefore, in the lithium polymer battery according to the present invention, leakage of the organic electrolyte is reduced and swelling at a high temperature is reduced, thereby preventing deterioration of safety and reliability of the battery.

Claims (17)

A lithium battery comprising a cathode and an anode capable of absorbing and dissipating lithium ions, a separator interposed therebetween, and a polymer electrolyte, The separator is chemically bonded to the polymer electrolyte as a polyolefin separator or a fluorinated polyolefin separator, The polymer electrolyte may include (a) 0.1 to 90% by weight of a compound represented by Formula 1, a compound represented by Formula 2, or a mixture thereof; (b) 0.1 to 90% by weight of a compound represented by Formula 3 below; And (c) 9.8 to 99.8% by weight of a non-aqueous organic solvent containing 0.5 to 2.0 mol / l (M) of a lithium salt. <Formula 1> CH (R1) = C (R2) -C (= O) O-R3-N (R4) (R5) <Formula 2> CH (R1) = C (R2) -C (= O) O-R3-CN <Formula 3> Z-[-Y-X-C (R2) = CH (R1)] n In Formulas 1, 2 and 3, R1 and R2 are each independently selected from hydrogen, C1 to C10 alkyl group, C1 to C10 fluorinated alkyl group, C1 to C10 aryl group, and C1 to C10 fluorinated aryl group One, R3 is any one selected from the following groups,

R4 and R5 may be any one selected from the following groups, and R4 and R5 may have the same structure.

X is any one selected from the following group, wherein R6 represents hydrogen, methyl group, ethyl group, propyl group or butyl group,

Y is any one selected from the following group, where m = an integer from 0 to 10:

n is an integer of 1-6, and Z has the following structure according to each n value. when n = 1, Z is hydrogen or an alkyl group of C1 to C12 when n = 2, Z is any one selected from

when n = 3, Z is any one selected from

when n = 4, Z is any one selected from

When n = 5 or 6, Z is any one selected from the following group.

delete According to claim 1, wherein the composition is any one or more polymerization initiators selected from the group consisting of benzophenone compound, diacyl peroxide compound, azo compound, peroxy ester compound, and peroxy carbonate compound Lithium battery, characterized in that it further comprises 0.1 to 10% by weight based on the total amount of the compound represented by the formula (1), (2) and (3). The lithium battery according to claim 3, wherein the benzophenone compound is benzophenone or substituted benzophenone. The lithium battery according to claim 3, wherein the diacyl peroxide compound is benzoyl peroxide, acetyl peroxide or lauroyl peroxide. The azo compound is azobisisobutyronitrile (AIBN), azobis (2,4-dimethyl valeronitrile) (azobis (2,4-dimethyl valeronitrile)), or azobis (cyclo) Hexanecarbonitrile) (azobis (cyclohexanecarbonitrile)) lithium battery characterized in that. The lithium battery according to claim 3, wherein the peroxy ester compound is t-butyl peroxy ester or t-amyl peroxybenzoate. The method of claim 3, wherein the peroxy carbonate compound is t-butyl peroxy isopropyl carbonate (t-butyl peroxy isopropyl carbonate) or t-butyl peroxy 2-ethylhexyl carbonate (t-butyl peroxy 2-ethylhexyl carbonate) Lithium battery characterized by the above-mentioned. According to claim 1, wherein the polyolefin separator or fluorinated polyolefin separator is a polyethylene separator, polypropylene separator, polyvinylidene fluoride separator, vinylidene fluoride and hexafluoropropylene copolymer separator, polyethylene / polypropylene two layers A separator, a three layer separator of polypropylene / polyethylene / polypropylene, or a three layer separator of polyethylene / polypropylene / polyethylene. The method of claim 1, wherein the lithium salt is LiPF ₆ , LiClO ₄ , LiBF ₄ , LiBF ₆ , LiAsF ₆ , and LiN (SO ₂ CF ₃ ) ₂ , LiN (SO ₂ C ₂ F ₅ ) ₂ and perfluorosulfo Lithium battery, characterized in that at least one selected from the group consisting of lithium salt compounds. The method of claim 1, wherein the organic solvent is ethylene carbonate, propylene carbonate, dimethyl carbonate, methylethyl carbonate, diethyl carbonate, vinylene carbonate, triglyme, tetraglyme, fluorobenzene, difluorobenzene, γ- Lithium battery, characterized in that at least one selected from the group consisting of butyrolactone. The lithium battery according to claim 1, wherein the chemical bond is an ether bond. Providing a cathode, anode and polyolefin-based or fluorinated polyolefin-based separator; Irradiating the surface of the separator with actinic radiation to form peroxide groups on the surface of the separator; Manufacturing a unit cell assembly by interposing the separator between the cathode and the anode, and placing the battery into a battery case; 12. The radical produced by cleavage of the peroxide group is added to the composition according to any one of claims 1 and 3 to 11 inside the battery case, sealed, and heated. Polymerizing the compound of 1 to 3 to form a polymer electrolyte chemically bonded to the separator. The method of claim 13, wherein the actinic radiation is ultraviolet (UV) light, electron beam, γ-ray, glow discharge, or plasma. The method of claim 13, wherein the peroxide group is a hydroperoxy group (-OOH). The method of claim 13, wherein the thermal polymerization temperature is 20 to 100 ℃. 15. The method of claim 14, wherein in the case of using the ultraviolet (UV) light, peroxide groups are formed on the surface of the separator using light having a wavelength of 200 to 400 nm.

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