KR100385701B1 - Lithium battery and method for preparing the same - Google Patents

Abstract

The present invention relates to a lithium battery and a method for manufacturing the same, for this purpose: a) a positive electrode in which a polymer electrolyte is coated on an electrode coated with a positive electrode material on a positive electrode current collector so that the electrode and the electrolyte are integrated; b) a negative electrode in which an electrode and an electrolyte are integrated by coating a polymer electrolyte on a negative electrode having a negative electrode material coated on a negative electrode current collector; c) a separator positioned between the positive electrode of a) and the negative electrode of b) to separate the positive electrode and the negative electrode and at the same time to reinforce the mechanical strength of the polymer electrolyte; And d) a positive electrode of a), a negative electrode of b), and an electrolyte solution impregnated with a separator, and a method of manufacturing the same.

Since the lithium battery of the present invention is integral with the electrode and the electrolyte, the internal resistance of the battery is small, so that the high rate characteristic is not only good, but also the polymer electrolyte sufficiently supports the electrolyte solution, and thus the low temperature characteristic is also excellent. This feature can be used as a power source for portable home appliances such as cordless phones, notebook computers, camcorders, and even electric power for electric vehicles.

Description

Lithium battery and its manufacturing method {LITHIUM BATTERY AND METHOD FOR PREPARING THE SAME}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lithium battery, and in particular, a lithium battery having a low interfacial resistance between an electrode and an electrolyte, having low internal resistance of the battery, having a high rate characteristic, a high mechanical strength, and an electrolyte sufficiently supporting an electrolyte solution, and having excellent low temperature characteristics. It relates to a manufacturing method thereof.

Conventional lithium battery manufacturing methods can be broadly classified into two types: a method of manufacturing a lithium ion battery using a separator and a liquid electrolyte, and a method of manufacturing a lithium polymer battery using a polymer electrolyte.

Lithium ion batteries are manufactured by manufacturing a cylindrical battery and a rectangular battery by winding a separator between each electrode to make a jelly roll. A lithium polymer battery is manufactured by laminating each electrode with a polymer electrolyte. Doing.

The two manufacturing methods have the following characteristics. In the manufacturing method of the lithium ion battery, since the separator is used, the mechanical strength is high, but the separator and the electrode are not integrated. In addition, since the battery separator does not sufficiently impregnate the electrolyte, the battery is placed in a can of iron or aluminum, and the electrolyte is added in excess.

The characteristics of the polymer cell can be seen in US Belcoa patents (US Pat. Nos. 5,296,318, 5,456,000, 5,470,357, and 5,478,668). It is not possible to thin the electrolyte because it does not maintain sufficient mechanical strength, and the manufacturing process is very complicated. In addition, since the thickness of the electrolyte is thicker than that of the ion battery, and the electrolyte is not sufficiently impregnated with the electrolyte, the characteristics are inferior to that of the ion battery.

In particular, the speed characteristics and low temperature characteristics are poor. In addition, since the polymer battery does not have high mechanical strength of the electrolyte, it is difficult to reduce the thickness of the polymer electrolyte to 40 μm or less because of safety concerns. Because of the thickness of the electrolyte, the rate characteristic of the battery is poor.

In view of the problems of the prior art, an object of the present invention is to provide a lithium battery having excellent high rate characteristics, excellent mechanical strength and excellent low temperature characteristics and a method of manufacturing the same.

Another object of the present invention is to provide a lithium battery having a low interfacial resistance between an electrode and an electrolyte, and a manufacturing method thereof.

Another object of the present invention is to provide a lithium battery and a method for manufacturing the same, which reinforce the mechanical strength of a polymer electrolyte by using a separator having high mechanical strength.

Still another object of the present invention is to provide a lithium battery and a method for manufacturing the same, in which a polymer electrolyte coated on an electrode surface sufficiently supports an electrolyte solution.

1 is a schematic view showing a positive electrode in which a polymer electrolyte is coated on a cross section of a positive electrode and the electrode and the polymer electrolyte are integrally bonded.

Fig. 2 is a schematic diagram showing the structure of a battery in which a thin film separator is interposed between a single-sided electrode and each electrode in which a polymer electrolyte is integrally bonded.

3 is a schematic view showing a positive electrode in which a polymer electrolyte is coated on both sides of a double-sided positive electrode and the electrode and the polymer electrolyte are integrally bonded.

4 is a schematic view showing the structure of a battery in which a separator of a thin film is interposed between a double-sided electrode and each electrode in which a polymer electrolyte is integrally bonded.

Reference numeral 1 denotes a polymer electrolyte; 2 is an anode material; 3 is a positive electrode current collector; 4 is a negative electrode material, 5 is a negative electrode current collector, and 6 is a separator.

The present invention, in order to achieve the above object, in a lithium battery,

a) a polymer electrolyte is coated on an electrode having a positive electrode material coated on the positive electrode current collector

An anode in which an electrode and an electrolyte are integrated;

b) a polymer electrolyte is coated on the negative electrode having a negative electrode material coated on the negative electrode current collector

A cathode in which an electrode and an electrolyte are integrated;

c) separating the positive electrode and the negative electrode between the positive electrode of a) and the negative electrode of b)

Separator; And

d) the electrolyte solution impregnated with the anode of a), the cathode of b), and the separator

It provides a lithium battery comprising a.

In addition, the present invention is a method of manufacturing a lithium battery comprising an electrode, an separator, and an electrolyte in which an electrode and an electrolyte are integrated,

a) a polymer electrolyte on an electrode prepared by coating an electrode material on each electrode current collector

Coating and drying the slurry;

b) placing a separator between the positive electrode and the negative electrode of the electrode prepared above to

Assembling;

c) thermally curing the polymer electrolyte by heating the assembled cell under vacuum

Making a step; And

d) injecting a liquid electrolyte into the cell

It provides a method for producing a lithium battery comprising a.

Hereinafter, the present invention will be described in detail.

In the lithium battery of the present invention, the internal resistance of the battery is small and the distance between the electrodes is reduced to the maximum, thereby reducing the migration path of ions to improve the performance of the battery and using a thin film separator having excellent mechanical strength between the polymer electrolytes. The mechanical strength of the polymer electrolyte is reinforced, and the polymer electrolyte made of a material capable of sufficiently impregnating the liquid electrolyte is used to improve the low temperature performance of the battery.

To this end, the lithium battery of the present invention has an excellent interfacial property by integrating the electrode and the electrolyte by coating a polymer electrolyte directly on the electrode material of the electrode, and using a separator of a thin film having strong mechanical strength between the anode and the cathode. The strength was excellent, and the low temperature performance was improved by using a polymer electrolyte as the electrolyte so that the liquid electrolyte was sufficiently supported.

The lithium battery of the present invention is applicable to all types of batteries, such as the jelly roll form of a conventional lithium ion battery and the lamination form of a lithium polymer battery.

The method of integrating the electrode and the electrolyte of the present invention is to coat a polymer electrolyte on the electrode.

To this end, the electrode is prepared by mixing an electrode active material, a conductive agent and a binder to make a slurry and coating it on a current collector. In this case, the manufactured electrode is roll pressed to increase the packing density of the electrode and at the same time make the surface of the electrode uniform and smooth. The current collector of the electrode may be a metal foil such as a lithium ion battery, or a metal expanded mesh described in Belcoa patents (US Pat. Nos. 5,296,318, 5,456,000, 5,470,357, and 5,478,668). metal extended mesh) may be used. In addition, when the metal expanded mesh is used, an electrode film may be separately coated, and then the film may be thermally bonded to the metal mesh to prepare an electrode. The electrode may be a single-sided electrode using only one side of the current collector, or may be a double-sided electrode using both sides of the current collector. Figure 1 shows a single-sided anode, Figure 3 shows a double-sided anode.

In addition, first to prepare a polymer electrolyte slurry to coat the polymer electrolyte on the electrode. At this time, the polymer electrolyte slurry is prepared by dissolving the polymer in acetonitrile, which is a solvent, adding a curing agent and a reaction initiator thereto and maintaining a proper viscosity.

Here, the polymer is an amorphous polymer, in which a high molecular weight comb-shape PEO having a side chain in the main chain of the polymer or an acrylic ester group terminated at the end of the side chain is present. Use of polyethylene esters terminated high molecular weight comb-shape PEO with attached main chains of high molecular weight or common polyethylene oxide, polypropylene oxide, polymethyl methacrylate It may be a PMMA, a polyether series compound or a mixture of these compounds, and polyacrylonitrile (PAN) or polyvinylidene fluoride (PVdF) may be applied.

In addition, an inorganic filler may be added to the polymer electrolyte slurry. Examples of the inorganic filler include aluminum oxide (Al ₂ O ₃ ), fumed silica, zeolite, and titanium oxide (TiO ₂ ). , Barium titanate (BaTiO ₃ ), and the like, and may be selected from one or more of these groups and added. The particle size of the inorganic filler powder is a fine powder of 1 μm or less.

In addition, the polymer electrolyte slurry may include a curing agent, and acrylate-based and bismaleimide-based may be used, and acrylate-based ethoxylated bisphenol dimethyl acrylate (Ethoxylated Bisphenol Dimethylacrylate) and ethoxylated trimethylolpropane (Ethoxylated Trimethylolpropane Triacrylate, Triethylene Glycol Dimethacrylate, Ethylene Glycol Dimethacrylate, Polyethylene Glycol Diacrylate, etc. can be used, and Bismaleimide-based N , Nm-phenylene bismaleimide (N, Nm-Phenylene bismaleimide) and the like can be used. The amount added is used in the range of 2 to 15% by weight based on the polymer. Less than 2% by weight of the polymer is less cross-linking is less effective, more than 15% by weight of the cross-linking occurs a lot to reduce the ionic conductivity of the electrolyte.

The polymer electrolyte slurry also contains reaction initiators such as benzoyl peroxide, dicumyl peroxide, azo-bis-isobutyronitrile, azodicarboxylic acid Azodicarboxylic acid bisdimethylamide may be used, etc. In particular, such a reaction initiator should be selected according to the reaction temperature, and when the reaction temperature is set at about 100 ° C., benzoyl peroxide is preferable. Depending on the type, but calculated according to the type and amount of the reactor, 1 to 10% by weight based on the polymer is added, preferably 5 to 6% by weight. If it is more than% by weight, an unreacted initiator remains, which may cause a problem in the cell reaction.

The polymer electrolyte slurry thus prepared is coated on the surface of the electrode material of the electrode, and the coating thickness is preferably adjusted to 1 to 15 μm after drying. When the thickness is less than 1 μm, not only is it difficult to coat, but also the performance is poor because the electrolyte is not sufficiently impregnated with the electrolyte. Worsen the character.

After the polymer electrolyte is coated on the electrode, it is dried, the electrode is cut into a predetermined size, and then the battery assembly process is started. In particular, it is preferable to completely remove the residual solvent, etc. remaining in the film by vacuum drying before the assembly process, the battery assembly is preferably carried out in a dry room (dry room).

The assembly of the battery may be a method of manufacturing a lithium ion battery made by inserting a separator between electrodes and winding, and laminating and laminating bonding as in a polymer battery. The separator uses a porous film having a thickness of 1 to 15 µm, and the material is two or more layers of a film selected from the group consisting of polyethylene and polypropylene, a mixture film of these groups, or a film of these groups. The laminated multilayer film is preferable. When the thickness is 1 μm or less, not only the mechanical strength of the film is weak but also difficult to handle in the process, and when the thickness is 15 μm or more, the distance between the electrodes becomes far. In the present invention, since the polymer electrolyte is used while being integrated with the electrode, it is possible to obtain a strength supplementary effect even if the separator is thinner than the conventional separator. Therefore, there is an advantage that a thinner separator may be used than a general lithium ion battery using a separator having a thickness of 20 μm or more, and as a result, the gap between the electrodes may be further reduced.

The assembled battery thus manufactured is subjected to a vacuum drying process as a next step. The vacuum is first maintained to remove impurities such as solvent and moisture remaining in the electrode and the polymer electrolyte, and then the temperature is raised until the reaction temperature of the thermosetting initiator is reached to cause the polymer electrolyte to cure. The holding temperature is maintained so as to have a deviation within 20 degrees above and below the reaction temperature of the thermosetting initiator. The curing reaction method and conditions can be different, except for the thermosetting method may be carried out under a nitrogen or argon atmosphere for an inert atmosphere instead of using a UV and an electron beam (electron beam) and a vacuum.

In the thermosetting process, not only the bonding between the electrode and the polymer electrolyte is improved, but also the bonding between the polymer electrolyte on the electrode through the separator occurs and is connected to each other to form an integrated body such as a polymer battery made by the Belcoa patent.

The assembled battery, which is integrated, is placed in an electrolyte so that the electrolyte permeates the polymer electrolyte, the separator and the electrode. When the appropriate amount of electrolyte is impregnated, the surface of the battery is cleaned and packaged in a battery package. In this process, there is a method of omitting the impregnation of the battery by putting it in the electrolyte, and putting the assembled battery directly into the package, and then adding an appropriate amount of electrolyte and sealing the electrolyte. These two methods can be selectively applied considering the characteristics of the process. In addition, the electrolyte solution uses a lithium salt-containing organic electrolyte solution, and may be used depending on the type of electrode active material.

Since the lithium battery of the present invention has high mechanical strength and an integrated electrode and an electrolyte, the internal resistance of the battery is small, so that the high rate characteristic is not only good, but also the polymer electrolyte sufficiently supports the electrolyte solution, and thus the low temperature characteristic is also excellent.

The present invention will be described in detail through the following examples and comparative examples. However, an Example is for illustrating this invention and is not limited only to these.

EXAMPLE

All the raw materials used in the examples were dried in a vacuum drying furnace for 24 hours or more before use to completely remove the moisture contained therein, and coater was used as a lab dryer of Matis. The internal resistance of the battery was measured using a potentiometer (potentiomer model 273 from EG G) and an impedance analyzer (Solartron SI 1260 Impedance Analyzer). The charging and discharging experiments and the battery characteristic evaluation experiments were performed by Toyo's charging and discharging experiments.

Example 1

Jelly Roll Type Lithium Battery

(Manufacture of Anode Electrode-Preparation of Electrode Using Metal Foil Current Collector)

After dissolving 3 g of binder (PVdF) in 40 g of solvent (NMP; N-methylpyrrolidone), 91 g of lithium cobalt oxide (LiCoO ₂ ) and 6 g of a conductive agent (graphite: KS-6) were added as an electrode active material. Stirring to prepare a slurry of appropriate viscosity. The slurry was coated on aluminum foil (Al foil), which is a current collector, by a doctor blade method, and the thickness of the electrode was adjusted to 100 to 120 μm after coating, to prepare a positive electrode (both electrodes). In manufacturing, coat one side and then the back side in the same way).

A roll press before the coating of the polymer electrolyte on the electrode generally allowed about 30-40% of the initial electrode thickness to be pressed.

When using lithium nickel oxide (LiNiO ₂ ) or lithium manganese oxide (LiMn ₂ O ₄ ) as the active material, the slurry composition was 85% by weight of the active material, 9% by weight of the conductive agent, and 6% by weight of the binder. The same as in and the manufacturing method can be the same.

(Manufacture of Cathode Electrode-Preparation of Electrode Using Metal Foil Current Collector)

In the case of the negative electrode as well as the positive electrode, 10 g of a binder (PVdF) was dissolved in 80 g of a solvent (NMP; N-methyl pyrrolidone), and 90 g of graphite (MCMB 10-28) was added as an electrode active material, followed by stirring to prepare a slurry. Then, the slurry was coated on a copper foil (Cu foil) having a current collector thickness of 10 μm in the same manner as a positive electrode to prepare an electrode. The thickness of the electrode was adjusted to 80 to 120 ㎛ after drying.

(Polymer Polymer Slurry Preparation)

10 g of acrylic esters terminated high molecular weight comb-shape PEO with a high molecular weight main chain with acrylic esters group terminated on the side chains, with inorganic filler 1 g of fumed silica, 0.5 g of bismaleimide-based N, Nm-phenylene bismaleimide as a thermosetting agent, and 0.03 g of benzoyl peroxide as a curing initiator Was added to 90 g of acetonitrile solvent to prepare a polymer electrolyte slurry. In this case, first, the polymer is completely dissolved in a solvent, and then an inorganic filler is added to the solution to completely disperse it. The slurry was prepared by adding a thermosetting agent and a curing reaction initiator to dissolve and stir to disperse uniformly.

(Manufacture of integrated electrode)

The polymer electrolyte slurry prepared above was coated on the electrode material of the positive electrode to integrate the positive electrode and the electrolyte as shown in FIG. 1. Like the positive electrode, the negative electrode was coated with a polymer electrolyte slurry on the negative electrode material to integrate the negative electrode and the electrolyte.

The coating method was the same as the doctor blade (Doctor blade) method as in the electrode manufacturing, the coating thickness was adjusted to 80 ~ 120 ㎛ range of the gap so that the thickness of the polymer electrolyte 4 ~ 6 ㎛ after drying, mainly 120 ㎛ . At this time, since the electrode is not dissolved in the solvent acetonitrile of the slurry, the shape of the electrode is maintained as it is. After drying the electrode is cut to a certain size and used in the next step, the assembly process.

(Battery assembly)

The battery is assembled using the electrode coated with the polymer electrolyte on the surface prepared above. In the battery assembly process, the separator is sandwiched between the positive electrode and the negative electrode in the case of the single-sided electrode, and then wound to assemble the battery. In the battery design, the battery capacity was 500 mAh.

In order to heat-harden the battery assembled above, it puts into a vacuum oven, and then raises a temperature gradually, drying in a vacuum atmosphere. The holding temperature was maintained at 110 ° C., which is 5 to 10 degrees higher than the reaction temperature of the thermosetting initiator. First, in the vacuum process below 100 ° C., the solvent or water remaining in the polymer electrolyte coating may be completely removed, and at 100 ° C. or higher, a curing reaction may occur to improve the mechanical strength of the polymer. Through the curing reaction, the interface property between the electrode and the polymer electrolyte coated on the surface is improved, and the polymer electrolyte of the positive electrode is connected through the separator.

(Electrolyte injection)

This process is to impregnate the electrolyte by injecting the electrolyte into the assembled battery to put the assembled battery in the liquid electrolyte so that the electrolyte is sufficiently impregnated in the battery for 1 hour. After that, put into a battery case and seal. The battery case is sealed by a vacuum thermal bonding method in an aluminum laminate battery packaging pack.

At this time, the electrolyte was used EC + 2EMC + LiPF ₆ 1 mol.

(Battery evaluation)

The performance of the battery thus prepared was measured by using an impedance analyzer to measure the internal resistance of the battery, and by using a charge / discharge tester, the capacity, life, speed, and temperature of the battery were measured.

The internal resistance of the battery was measured after sealing for 5 hours after the battery was manufactured, and the capacity was measured after removing the gas in the battery packaging by vacuum and sealing and discharging again after 2 cycles after 5 cycles of charging and discharging. The capacity for the cycle was taken as the capacity of the cell. The life characteristics were charged and discharged at room temperature from 4.2 to 3.0V at a C / 5 rate using the standard method of battery evaluation, and the capacity at 200 times was compared with the initial capacity.

The speed characteristics were charged and discharged in the voltage range 4.2-3.0V at 1C speed at room temperature, and the capacity at 5-10 times was compared with the initial capacity at C / 5 speed. In the case of low temperature characteristics, the battery was charged at room temperature at a rate of 1 / 5C, discharged at -10 ° C, and the capacity at 5 to 10 times was compared with the initial capacity at room temperature C / 5. The performance of the cell is shown in Table 1.

Comparative Example 1

Lithium ion battery

A battery was manufactured in the same manner as in Example 1, except that the polymer electrolyte was not coated on each electrode surface.

In the preparation of the positive electrode, the composition consists of 3 g of binder (PVdF), 40 g of solvent (NMP; N-methylpyrrolidone), 91 g of electrode active material lithium cobalt oxide (LiCoO ₂ ), and 6 g of a conductive agent (graphite: KS-6). to be. The slurry was prepared by adjusting the electrode thickness to 100 to 120 μm after drying in an aluminum foil having a thickness of 20 μm, which is a current collector, in the same manner as in Example 1 (when manufacturing a double-sided electrode, the back side was coated. Was coated in the same way). A roll press prior to coating the polymer electrolyte on the electrode generally allows about 30-40% of the initial electrode thickness to be pressed.

In the preparation of the negative electrode, the composition is 10 g of a binder (PVdF), 80 g of a solvent (NMP; N-methyl pyrrolidone), and 90 g of an electrode active material graphite (MCMB) 10-28. The electrode used a copper foil (Cu foil) of 10 ㎛ and the thickness of the electrode was adjusted to 80 ~ 120 ㎛ after drying.

The battery assembly was designed to have a capacity of 500 mAh, and a polyethylene-based 20 μm separator was placed between the electrodes and wound with a square jelly roll to make a battery. Jelly roll is added to 1 mol of electrolyte EC + 2EMC + LiPF ₆ so that the electrolyte is sufficiently immersed in the battery for 1 hour, and then put into the battery case and sealed. The battery case is sealed by a vacuum thermal bonding method in an aluminum laminate battery packaging pack.

(Battery evaluation)

Performance evaluation of the battery was carried out by the evaluation method of Example 1, the results are shown in Table 1.

Example 2

Laminated Lithium Battery

(Manufacture of Anode Film)

In a sealed reaction vessel, 10 g of PVdF homopolymer (solef 1015) is added to 100 ml of a mixed solvent having a mixing ratio of dimethylformamide and acetone in a volume ratio of 25: 75, and the temperature is maintained at 60 ° C. while stirring. After dissolving in, to prepare a clear solution, 16 g of dibutyl phthalate and 2.5 g of conductive carbon (super-P) were added thereto as a plasticizer and dispersed therein, followed by graphite (MCMB 10-28 by Osaka Gas Co., Ltd.) 40 as an active material. The g was added in 5 g portions at 5 minute intervals and further stirred for 30 to 60 minutes while maintaining the temperature to prepare a uniformly dispersed slurry.

The slurry was coated on a release paper treated with silicon to prepare a film. Here, the applicator (mathis lab dryer) was adjusted to have a constant thickness by using a micro thickness meter (micro thickness meter) on the left and right sides of the applicator, the coating is 0.5 while preventing the pin hole (pin hole) is generated in the film The electrode thickness after drying was 70-90 micrometers at the application rate of -1 m / min.

(Manufacture of Anode Film)

The manufacturing method is the same as the manufacturing method of the negative electrode, and the composition is 10 g of PVdF homopolymer (solef 1015), a plasticizer, 14 g of dibutyl phthalate, 5.5 g of conductive carbon (super-P), and a lithium having an average particle size of 10 μm. 50 g of cobalt oxide (LiCoO ₂ ). The solution was prepared. The thickness of the electrode was set to 70 to 90 µm.

(Electrode manufacture)

Electrodes were prepared by laminating each electrode film prepared above on a current collector. The current collector for the negative electrode was made of a copper expanded mesh, and the positive electrode current collector was made of an aluminum expanded mesh.

Each current collector is washed with acetone to remove organic substances adsorbed on the surface, and then immersed in strong acid etching solution to oxidize the surface and washed with pure water several times to completely remove the acid, dry and use.

The negative electrode was thermally bonded to a copper expanded mesh (Cu expended mesh) in the form of a laminate of the negative electrode film-copper current collector-negative electrode film prepared above. The thermal bonding device is a laminator in which temperature and pressure are constantly adjustable and heating rolls are installed up and down. At the time of negative electrode bonding, the negative electrode film was placed on both sides with the pretreated current collector in between to be simultaneously bonded at the same time. The junction temperature was adjusted to be constant at 145 ~ 160 ℃. When the temperature was higher or the pressure was increased during the bonding, the electrode shape was distorted, and thus the bonding was carried out with constant adjustment.

The positive electrode was thermally bonded in the laminate form of the positive electrode film-aluminum current collector-anode film to the aluminum expanded mesh which is a current collector. The thermal bonding conditions are the same as in the cathode.

(Manufacture of integrated electrode)

Each electrode prepared by joining the above was put in diethyl ether which is an extraction solvent and completely removed from the plasticizer for 2 hours and dried. After that, the method of coating the polymer electrolyte on the electrode surface was the same as in Example 1. The composition and material of the polymer electrolyte are also the same as in Example 1. The thickness of the coating was adjusted by adjusting the gap in the range of 80 to 120 μm so that the thickness of the polymer electrolyte was 4 to 6 μm after drying, and mainly 120 μm (both electrodes were coated on one side and then on the back side).

(Battery Assembly and Packaging)

The battery assembly was designed to have a battery capacity of 500 mAh, and a battery was manufactured by inserting a polyethylene-based 15 μm separator between the electrodes and stacking the battery in a square. The battery is placed in an electrolyte solution (EC + 2EMC + LiPF ₆ 1 mol) so that the electrolyte is sufficiently immersed in the battery for 1 hour, and then put into the battery case and sealed. The battery case is sealed by a vacuum thermal bonding method in an aluminum laminate battery packaging pack.

(Battery evaluation)

Performance evaluation of the battery was carried out by the evaluation method of Example 1, the results are shown in Table 1.

Comparative Example 2

Lithium polymer battery

(Production of Electrode)

As the negative electrode and the positive electrode, the electrode film and the electrode prepared in Example 2 were used as it is.

(Manufacture of Electrolyte Film)

The polymer used in the electrolyte was either a PVdF copolymer alone or a polymer blended with a PVdF copolymer and a PVdF homopolymer. Acetone was used as a solvent when the PVdF copolymer was used alone, and a mixed solvent was used when the blended polymer was used.

In a closed reaction vessel, 9 g of PVdF polymer was added to 100 ml of a mixed solvent having a mixing ratio of dimethylformamide and acetone in a volume ratio of 25: 75, and the temperature was maintained at 60 ° C. while stirring to dissolve the polymer in a solvent to prepare a clear solution. Thereafter, 10 g of dibutylphthalate as a plasticizer and 1 g of fumed silica as an inert filler were added thereto, followed by further stirring for 30 to 60 minutes while maintaining the temperature, thereby preparing a uniformly dispersed transparent slurry solution.

The slurry solution was coated on a release paper surface-treated with silicon using a coater to prepare a film. Here, the applicator (mathis lab dryer) was adjusted to have a constant thickness by using a micro thickness meter (micro thickness meter) on the left and right sides of the applicator, the coating is 0.5 while preventing the pin hole (pin hole) is generated in the film The film thickness after drying was made into 40 micrometers at the application | coating speed | rate of -1 m / min.

(Bonding of cathode and electrolyte film)

The negative electrode prepared above and the 40 μm electrolyte film were thermally bonded in the form of a laminate of an electrolyte film-cathode-electrolyte film.

The thermal bonding device is a laminator in which temperature and pressure, such as cathode production, are constantly adjustable and heating rolls are installed up and down.

The electrolyte film was placed on both sides with the negative electrode interposed therebetween to simultaneously bond them together. If the bonding is good, the electrolyte film will be dissolved and transparent, and if the temperature is raised above the proper value or the pressure is increased, the film will weaken and cause an internal short circuit. Therefore, the bonding temperature is controlled to 130 ~ 140 ℃ and the pressure is kept constant. It was.

(Battery bonding)

The capacity of the battery was designed to be 500 mAh, and the battery substrate was manufactured by thermally bonding a cathode, an electrolyte film assembly, and the cathode prepared in the above in the form of a laminate of a cathode, an anode, and an electrolyte assembly.

The positive electrode was placed on both sides with the negative electrode and the electrolyte film assembly therebetween to be simultaneously bonded at the same time. The junction temperature was controlled to be constant at 135-150 ° C. and the pressure was constant.

(Solvent extraction)

In the battery substrate prepared above, a plasticizer containing films of the battery substrate was extracted by using an extraction solvent diethyl ether to form micropores in the film. This extraction was carried out for 30 minutes in the battery substrate in the extraction solvent, and then extracted again for 30 minutes in a fresh extraction solvent and dried for 30 minutes at room temperature vacuum.

(Electrolyte impregnation and packing)

Ethylene containing 1 mole of lithium hexafluoride (LiPF ₆ ) salt in a glove box filled with argon gas and having no contact with air inside the battery substrate having micropores formed by the plasticizer extraction. A battery was prepared by impregnating carbonate and ethylmethyl carbonate mixed electrolyte for 1 hour.

The battery prepared above was sealed by vacuum thermal bonding in an aluminum laminate battery packaging pack to prepare a battery that can be finally used.

(Battery evaluation)

Performance evaluation of the battery was carried out by the evaluation method of Example 1, the results are shown in Table 1.

division Example 1 Comparative Example 1 Example 2 Comparative Example 2 Battery type Polymer electrolyte on or off electrode surface (Integrated) radish (Integrated) None (integrated) Electrolyte Polymer Electrolyte + Separator Separator Polymer Electrolyte + Separator Polymer electrolyte Internal resistance (Ω / ㎠) 34-37 38-42 35 to 39 36-40 Capacity characteristic (%) 520 mAh 520 mAh 510 mAh 500 mAh Life Characteristics (%) 88 82 96 84 Speed characteristic (%) 97 97 94 92 Low temperature characteristics (%) 82 80 81 78

Since the lithium battery of the present invention is integral with the electrode and the electrolyte, the internal resistance of the battery is small, so that the high rate characteristic is not only good, but also the polymer electrolyte sufficiently supports the electrolyte solution, and thus the low temperature characteristic is also excellent. This feature can be used as a power source for portable home appliances such as cordless phones, notebook computers, camcorders, and even electric power for electric vehicles.

Claims (15)

In a lithium battery, a) a polymer electrolyte is coated on an electrode having a positive electrode material coated on the positive electrode current collector An anode in which an electrode and an electrolyte are integrated; b) a polymer electrolyte is coated on the negative electrode having a negative electrode material coated on the negative electrode current collector A cathode in which an electrode and an electrolyte are integrated; c) separating the positive electrode and the negative electrode between the positive electrode of a) and the negative electrode of b) Separator; And d) the electrolyte solution impregnated with the anode of a), the cathode of b), and the separator Lithium battery comprising a. The method of claim 1, The positive electrode current collector of a) and the negative electrode current collector of b) are metal foil or metal expanded mesh. The method of claim 1, The polymer electrolyte of the positive electrode of a) and the polymer electrolyte of the negative electrode of b) are amorphous polyethylene oxide, polyethylene oxide, polypropylene oxide, polymethyl methacrylate, and polyether type. A lithium battery, which is a blend compound selected from the group consisting of compounds consisting of two or more selected from these groups. The method of claim 3, wherein The polymer electrolyte is one from the group consisting of aluminum oxide (Al ₂ O ₃ ), fumed silica, zeolite, titanium oxide (TiO ₂ ), and barium titanate (BaTiO ₃ ) type The lithium battery containing the inorganic filler chosen above. The method of claim 1, The lithium battery whose coating thickness of the polymer electrolyte of the positive electrode of a) and the polymer electrolyte of the negative electrode of b) is 1-15 micrometers. The method of claim 1, Lithium battery whose thickness of the separator of said c) is 1-15 micrometers. The method of claim 1, The separator of c) is a porous film, and the material is a film selected from the group consisting of polyethylene, polypropylene, and mixtures thereof, or a multilayer film obtained by laminating two or more layers of films of these groups. Phosphorus lithium battery. The method of claim 1, A lithium battery in which the polymer electrolyte of the positive electrode of a) and the polymer electrolyte of the negative electrode of b) are contacted by an adhesive force. The method of claim 1, The lithium battery is a jelly roll type or a laminated type. In the manufacturing method of a lithium battery comprising an electrode, an separator, and an electrolyte in which an electrode and an electrolyte are integrated, a) a polymer electrolyte on an electrode prepared by coating an electrode material on each electrode current collector Coating and drying the slurry; b) placing a separator between the positive electrode and the negative electrode of the electrode prepared above to Assembling; c) thermally curing the polymer electrolyte by heating the assembled cell under vacuum Making a step; And d) injecting a liquid electrolyte into the cell Method for producing a lithium battery comprising a. The method of claim 10, The polymer electrolyte slurry of step a) is prepared by dispersing and dispersing a polymer, a thermosetting agent, a reaction initiator, and an inorganic filler in a solvent. The method of claim 11, The polymer is selected from the group consisting of amorphous polyethylene oxide, polyethylene oxide, polypropylene oxide, polypropylene oxide, polymethyl methacrylate, and polyether series, or two kinds thereof. Method for producing a lithium battery that is a mixture (blend compound) selected above. The method of claim 11, The inorganic filler is one from the group consisting of aluminum oxide (Al ₂ O ₃ ), fumed silica, zeolite, titanium oxide (TiO ₂ ), and barium titanate (BaTiO ₃ ) The manufacturing method of the lithium battery chosen above. The method of claim 10, Method for producing a lithium battery having a coating thickness of 1 to 15 ㎛ in step a). The method of claim 10, The battery assembly of step b) is a method of manufacturing a lithium battery by winding (winding) to produce a jelly roll type or lamination (lamination) to produce a laminated type.