KR20040005550A - Method of making lithium ion polymer battery and porous polymeric electrolte - Google Patents

Abstract

PURPOSE: Provided are a process for producing a lithium ion polymer electrolyte having high ionic conductivity and excellent adhesive force with electrodes after gelation and a process for producing a lithium ion polymer battery excellent in performance like high efficiency and cycle property by using the electrolyte. CONSTITUTION: The process for producing the lithium ion polymer electrolyte comprises the steps of: adding an organic solvent to a polymer compound at an ordinary temperature to 60deg.C to prepare a polymer solution of 1-20wt%; passing a polyolefin separation membrane through the polymer solution to prepare a coated separation membrane; drying the coated separation membrane at an ordinary temperature to 60deg.C to prepare a polymer porous separation membrane; soaking the polymer porous separation membrane in a lithium salt containing liquid electrolyte; gelating the soaked separation membrane at 60-100deg.C for 20 minutes to 3 hours. And the process for producing the lithium ion polymer battery comprises the steps of: preparing a cathode plate and an anode plate; preparing the polymer solution of 1-20wt%; preparing the polymer porous separation membrane; laminating the polymer porous separation membrane, the cathode plate, the polymer porous separation membrane, and the anode plate in order to form a first laminate; cutting the first laminate to a fixed size and laminating to form a second laminate or winding the first laminate; soaking the second laminate or the wound laminate in the lithium salt containing liquid electrolyte; sealing and gelating at 60-100deg.C for 1-24 hours.

Description

Lithium ion polymer electrolyte and method for manufacturing a battery including the same

The present invention relates to a lithium ion polymer electrolyte and a method for manufacturing a battery including the same. More specifically, a lithium or a lithium ion that is simplified in a manufacturing process through a gelation process during battery manufacturing using a polymer or a polymer porous membrane coated with a polymer and an inorganic material The present invention relates to an ion polymer electrolyte and a battery manufacturing method including the same.

Recently, with the rapid development of the electric, electronic, communication and computer industries, the demand for high performance and high safety secondary batteries has gradually increased. In particular, according to the trend of miniaturization, light weight, and portability of electric and electronic products, thinning and miniaturization of secondary batteries, which are key components in this field, are required.

Lithium ion batteries are currently used in mobile devices and electronic products, but lithium ion batteries use PE (polyethylene) or PP (polypropylene) separators as separators, so it is difficult to manufacture batteries by stacking electrodes and separators in the form of flat plates. It is rolled up and prepared into cylindrical and square barrels. The rectangular lithium ion battery manufactured in a roll type is currently commercialized, but the manufacturing process of the battery is difficult, it is restricted by the shape of the battery, and it shows a limitation in thinning and high capacity. In contrast, the lithium polymer battery may solve the above problem. It is expected to be. Lithium polymer battery has two kinds of membrane and electrolyte It is very advantageous in terms of productivity because it can be manufactured by stacking electrodes and solid polymer electrolytes on a flat plate according to the type of electrolyte using a solid polymer electrolyte having a function at the same time. .

The conventional solid polymer electrolyte production method was mainly based on polyethylene oxide (hereinafter referred to as PEO), but is very low in conductivity of about 10 ^-8 S / cm at room temperature and is not suitable for use alone. In order to solve this problem, a gel-type polymer electrolyte was developed to achieve a conductivity of 10 ⁻³ S / cm, and a representative gel-type polymer electrolyte is a polyacrylonitile (PAN) -based solid polymer electrolyte of US Pat. No. 5,219,679. However, the electrolyte disclosed in U.S. Patent No. 5,219,679 has a problem in that it is difficult to be used as a battery because of its excellent conductivity and adhesive strength with the electrode while having low mechanical strength.

The hybrid polyvinylidene fluoride (hereinafter referred to as PvdF) polymer compound described in U.S. Patent Nos. 5,296,319 and 5,460,904 to A. S. Gozdz et al. Has been developed to attempt mass production of a hybrid lithium polymer battery. However, this battery system has a difficulty in manufacturing process in which the plasticizer must be extracted later, since the plasticizer is added during the manufacture of the solid polymer electrolyte and the negative and positive electrodes. In addition, the PvdF-based electrolyte has excellent mechanical strength but poor adhesion, which requires a heat thinning process at a high temperature in manufacturing electrodes and batteries, and has a disadvantage in that battery performance is degraded due to peeling between the electrode and the solid polymer electrolyte during the extraction process.

Therefore, it is necessary to configure a battery using a gel electrolyte, but the gel electrolyte itself has a limit in mechanical strength. In order to solve this problem, there is a method of coating a gel electrolyte on the electrode as in Korean Patent No. 10-2000-7004714, but the method of coating the gel electrolyte on the electrode is difficult to generalize the technology and the manufacturing process must be made in a controlled inert atmosphere It has a disadvantage.

In addition, in the methods described in US Pat. Nos. 5,681,357, 5,688,293, and 5,834,135, a solution in which a polymer such as PvdF is dissolved in a solvent or a polymer in which a polymer such as PvdF is dissolved in an organic solvent electrolyte is used in a lithium ion battery. Alternatively, there is a method of manufacturing a battery by applying a PE separator and drying the separator and an electrode using a dried separator to integrate the electrode and the separator and injecting an organic solvent electrolyte thereto. The disadvantages of this method are that the polymer solution is cast on the PP or PE membrane, resulting in deformation of the PP or PE membrane or clogging the pores of the membrane, and inadequate contact because the electrode and the membrane are integrated by the heat thinning process. There is a disadvantage that the resistance increases. Due to this problem, high rate discharge characteristics are poor and cycle life characteristics are deteriorated.

In order to solve this problem, US Pat. No. 5,853,916 discloses a process of gelling at a constant pressure and temperature after forming a cell by coating a polymer on a polyolefin porous separator. In the battery manufacturing process, when the battery is manufactured by winding type, the pressure in the horizontal direction is relatively low because the pressure is applied up and down, and the ion conductivity path is limited to the gel electrolyte, so the high rate charge / discharge characteristics and cycle characteristics of the battery This has the disadvantage of deteriorating.

Therefore, it has excellent performances such as high rate charge and discharge characteristics and cycle characteristics, and can solve the disadvantages of manufacturing process complexity and high cost while maintaining the advantages such as thinning, large area, shape deformation and safety of lithium ion polymer battery. There is a need for a lithium ion polymer battery.

It is an object of the present invention to coat a polymer having a large pore on a polyolefin separator to allow ions to be transferred through a liquid phase and a gel phase formed in the separator, thereby producing an electrolyte having high ion conductivity and excellent adhesion to an electrode after gelation, and by using such an electrolyte. It is to provide a method for producing a lithium ion polymer battery having a simple manufacturing process and excellent performance.

1 (a) is a cross-sectional view of the porous polymer membrane according to the present invention,

1 (b) is a laminated cross-sectional view of the polymer porous separator, the negative electrode plate, and the positive electrode plate,

Figure 1 (c) is a laminated cross-sectional view of a polymer porous separator, a polymer-coated negative plate and a polymer coated positive plate,

2 is a process diagram schematically showing a manufacturing process of a lithium ion polymer battery according to the present invention;

3 is a SEM photograph of the polymer membrane coated on the porous PE membrane,

Figure 4 (a) is a SEM photograph of the polymer porous PE membrane prepared in Example 2 of the present invention,

Figure 4 (b) is a SEM photograph of the porous PE membrane used in the present invention,

Figure 5 (a) is a SEM photograph of the polymer porous PE membrane prepared by the amount of the polymer 2% by weight,

Figure 5 (b) is a SEM photograph of the polymer porous PE membrane prepared by the amount of the polymer 5% by weight,

6 is a SEM photograph of a porous polymer membrane formed by adding inorganic fine silica to a polymer component;

7 is a SEM photograph of a polymer membrane coated on a porous PE separator using a polymer solution mixed at 50 ° C. according to the present invention;

8 is a porous PE membrane SEM photograph of the porous polymer membrane coated by the phase separation method,

9 is a graph showing a high rate discharge characteristic for a battery prepared according to Example 10 of the present invention;

10 (a) is a comparison of the cycle characteristics of a battery prepared according to the process of the present invention using a polymer porous separator formed by coating a solution having a different polymer concentration on the porous PE separator, thereby

Figure 10 (b) is a comparison of the capacity characteristics of a battery prepared according to the process of the present invention using a polymer porous separator formed by coating a solution having a different polymer concentration on the porous PE separator, thereby

11 is a discharge capacity of a battery prepared according to the process of the present invention using a polymer porous membrane coated with a polymer solution mixed at 50 ^o C,

12 is a discharge capacity of a battery prepared according to the process of the present invention using a polymer porous separator formed by adding inorganic silica (fumed silica) to the polymer component,

13 (a) is a comparison of the cycle characteristics of a lithium ion polymer battery and a lithium ion battery prepared according to the present invention,

Figure 13 (b) is the discharge capacity of the lithium ion polymer battery and lithium ion battery prepared according to the present invention,

Figure 14 (a) is a comparison of cycle characteristics for the battery with or without the gelation process of the process of the present invention,

Figure 14 (b) is a comparison of the discharge capacity of the battery with or without the gelation process of the process of the present invention,

15 compares the cycle characteristics with or without the addition of minerals,

Figure 16 compares the cycle characteristics of the battery according to the presence or absence of the polymer coating on the electrode during the present invention.

According to the present invention, by adding an organic solvent to the polymer compound at a temperature of room temperature to 60 ℃ to prepare a polymer solution of 1-20% by weight; Preparing a coated separator by passing a polyolefin-based separator through the polymer solution; Preparing a polymer porous separator by drying the coated separator at a temperature of room temperature to 60 ° C .; Impregnating the polymer porous separator into a liquid electrolyte solution containing lithium salts; And gelling the impregnated polymer porous separator at a temperature of 60-100 ° C. for 20 minutes to 3 hours.

The polyolefin-based separator is preferably any one selected from the group consisting of a PE separator, a PP separator, and a multilayer separator of PE and PP.

The polymer solution manufacturing step may further include an inorganic material in the polymer compound, and by adding the inorganic material, the electrolyte content and retention ability of the gelled polymer may be increased, thereby improving cycle characteristics. The inorganic material is preferably any one selected from the group consisting of SiO ₂ , TiO ₂ , ZrO ₂ , Al ₂ O ₃ , BaTiO ₃ , Bi ₂ O ₃ , Fe ₂ O ₃ , CaSiO ₃ , and PbTiO ₃ .

The polymer porous separator has a pore of 0.1 to 20㎛, preferably 1 to 10㎛.

In addition, the above object, according to the present invention, by adding an organic solvent to the polymer compound at a temperature of room temperature to 60 ℃ to prepare a 5-30% by weight of the polymer solution; Mixing an additive with the polymer solution to form a binder solution; Passing the polyolefin-based separator through the binder solution to form a coated separator; Drying the coated separator at a temperature of room temperature to 60 ° C .; Preparing the polymer porous separator by removing the additive from the dried separator; Impregnating the polymer porous separator into a liquid electrolyte solution containing lithium salts; And gelling the impregnated polymer porous separator at a temperature of 60-100 ° C. for 20 minutes to 3 hours.

The additive is preferably an inorganic silica ball, it may be mixed in 1 to 15% by weight of the polymer solution.

And it is preferable that the polymer porous separator has a pore of 0.1 to 20㎛.

Method for producing a lithium ion polymer electrolyte according to the present invention comprises the steps of preparing a polymer solution of 5-30% by weight by adding an organic solvent to the polymer compound at a temperature of room temperature to 60 ℃; In the polymer solution Mixing the non-solvent and passing the poly-olipine-based separator to form a coated separator; Drying the coated separator at a temperature of room temperature to 60 ° C .; And removing the non-solvent in the dried coating separator with a detergent to prepare a polymer porous separator.

The polymer solution manufacturing step may further include an inorganic material in the polymer compound.

The nonsolvent is ethylene glycol, 1,2-propanediol, cyclohexanol, 1,4-dioxane, methyl alcohol, ethylene glycol diacetate, ethylene glycol diethyl ether, ethylene glycol monobenzyl ether One, two or more mixtures selected from the group consisting of ethylene glycol monobutyl ether, ethyl ethylene glycol monomethyl ether, ethylene glycol phenyl ether, and lauryl alcohol are preferred.

The cleaning agent is preferably one or two or more mixtures selected from the group consisting of ethanol, methanol, dimethyl ether, diethyl ether, dimethoxyethane, diethoxyethane, dimethyl carbonate, diethyl carbonate and hexane.

And the polymer porous separator has a pore of 0.1 to 20㎛, preferably having a pore size of 1 to 10㎛.

In accordance with the present invention, the above object is to prepare a positive electrode plate and a negative electrode plate; Preparing a polymer solution of 1-20% by weight by adding an organic solvent to the polymer compound at a temperature of room temperature to 60 ° C; Preparing a polymer porous separator by passing a polyolefin-based separator through the polymer solution; Sequentially stacking the polymer porous separator, the positive electrode plate, the polymer porous separator, and the negative electrode plate to form a first laminate; Cutting the first stack to a predetermined size and stacking the stack according to a stacking direction to form a second stack or winding the first stack to form a wound; Impregnating the second stack or the wound material with a liquid electrolyte containing lithium salt; And after sealing the impregnation can be achieved by a method for producing a lithium ion polymer battery comprising the step of gelling for 1-24 hours at 60 ~ 100 ℃.

The polymer solution manufacturing step may further include an inorganic material in the polymer compound.

And the step of preparing the positive electrode plate and the negative electrode plate is a step of preparing a polymer solution of 1-20% by weight by adding an organic solvent to the polymer compound at a temperature of room temperature to 60 ℃; Manufacturing a positive electrode plate having a polymer porous layer by passing the positive electrode plate through the polymer solution; And passing the negative electrode plate through the polymer solution to produce a negative electrode plate on which a polymer porous layer is formed.

In another aspect of the present invention for achieving the object of the present invention, preparing a positive electrode plate and a negative electrode plate; Preparing a polymer solution of 5-30% by weight by adding an organic solvent to the polymer compound at a temperature of room temperature to 60 ° C; Mixing an additive with the polymer solution to form a binder solution; Passing the polyolefin-based separator through the binder solution to form a coated separator; Drying the coated separator at a temperature of room temperature to 60 ° C .; Preparing the polymer porous separator by removing the additive from the dried separator; Sequentially stacking the polymer porous separator, the positive electrode plate, the polymer porous separator, and the negative electrode plate to form a first laminate; Cutting the first stack to a predetermined size to form a second stack to be stacked according to a stacking direction, or winding the first stack to form a wound; Impregnating the second stack or the wound material with a liquid electrolyte containing lithium salt; And after sealing the impregnation may include the step of gelling for 1-24 hours at 60 ~ 100 ℃.

The preparing of the positive electrode plate and the negative electrode plate may include adding an organic solvent to the polymer compound at a temperature of room temperature to 60 ° C. to prepare a 1-20 wt% polymer solution; Manufacturing a positive electrode plate having a polymer porous layer by passing the positive electrode plate through the polymer solution; And passing the negative electrode plate through the polymer solution to produce a negative electrode plate on which a polymer porous layer is formed.

In addition, the above object according to the present invention, manufacturing a positive electrode plate and a negative electrode plate; Preparing a polymer solution of 5-30% by weight by adding an organic solvent to the polymer compound at a temperature of room temperature to 60 ° C; In the polymer solution Mixing the non-solvent and passing the poly-olipine-based separator to form a coated separator; Drying the coated separator at a temperature of room temperature to 60 ° C .; Preparing a polymer porous separator by removing the non-solvent in the dried coating separator with a cleaning agent: sequentially stacking the polymer porous separator, the positive electrode plate, the polymer porous separator, and the negative electrode plate to form a first laminate Doing; Cutting the first stack to a predetermined size and stacking the stack according to a stacking direction to form a second stack or winding the first stack to form a wound; Impregnating the second stack or the wound material with a liquid electrolyte containing lithium salt; And after sealing the impregnation is achieved by a method for producing a lithium ion polymer battery comprising the step of gelling at 60 ~ 100 ℃ 1-24 hours.

The polymer solution manufacturing step may further include an inorganic material in the polymer compound.

The preparing of the positive electrode plate and the negative electrode plate may include: preparing a polymer solution of 1-20% by weight by adding an organic solvent to a polymer compound at a temperature of room temperature to 60 ° C .; Manufacturing a positive electrode plate having a polymer porous layer by passing the positive electrode plate through the polymer solution; And passing the negative electrode plate through the polymer solution to produce a negative electrode plate on which a polymer porous layer is formed.

According to the present invention, the object is to prepare a positive electrode plate and a negative electrode plate; Preparing a polymer solution of 1-20% by weight by adding an organic solvent to the polymer compound at a temperature of room temperature to 60 ° C; Manufacturing a positive electrode plate having a polymer porous layer by passing the positive electrode plate through the polymer solution; Manufacturing a negative electrode plate on which a polymer porous layer is formed by passing the negative electrode plate through the polymer solution; Sequentially stacking the positive electrode plate having the polymer porous layer, the polyolefin-based separator, and the negative electrode plate having the polymer porous layer formed thereon, to form a first laminate; cutting the first laminate to a predetermined size according to a stacking direction. Stacking to form a second laminate or winding the first laminate to form a wound; Impregnating the second stack or the wound material with a liquid electrolyte containing lithium salt; And after sealing the impregnation is achieved by a method for producing a lithium ion polymer battery comprising the step of gelling for 1-24 hours at 60 ~ 100 ℃.

Figure 1 (a) is a cross-sectional view of the polymer porous membrane according to the present invention, the gel-forming polymer layer 10 has a pore 11 and a gel-forming polymer matrix 12 of about 0.1 to 20㎛ size . Porous polyolefin separator 20 also has pores 21 and matrix 22. Here, the gel-forming polymer matrix 12 may be gelled, but the matrix 22 of the polyolefin porous separator is not gelled. If the pore 11 of the gel-forming polymer is too small, the effect of ionic conductivity through the liquid phase is reduced, and if the pore is too large, the adhesion to the electrode is inferior.

Hereinafter, the manufacturing process of the lithium ion polymer electrolyte will be described in more detail.

1. Porous Membrane Manufacturing

(1) Method by low concentration solution

The polymer or the polymer and the inorganic material are put into an organic solvent to prepare a 1-20 wt% polymer solution at an appropriate temperature, and then the porous polyolefin separator is passed through the solution. The porous polyolefin separator including the polymer solution loses the solvent as it passes through the drying stand and is coated with a polymer having a thickness of 1 to 20 μm.

The polymer component is polyvinylidene fluoride, polyvinycloride, polymethylmethacrylate, polymethacryl, in addition to the copolymer of vinyl denfluoride and hexafluopropylene. A polymer blend in which one or two or more selected from the group consisting of polymethacrylate, polyvinylalcohol, and polyethylene oxide is mixed is preferable.

The organic solvent is composed of tetrahydrofuran, acetone, acetonitrile, N-methylpyrrolidone, cyclohexanone, and chloroform. One or more mixtures selected from the group are preferred.

The polyolefin separator is composed of a PE single layer, a PP single layer, or a multilayer of PE and PP, and may be one having a mechanical strength that can be wound.

As the inorganic material, SiO ₂ , TiO ₂ , ZrO ₂ , Al ₂ O ₃ , BaTiO ₃ , Bi ₂ O ₃ , Fe ₂ O ₃ , CaSiO ₃ , PbTiO _3, and the like may be used.

(2) using additives

The polymer is placed in an organic solvent to prepare a 5-30% by weight polymer solution at an appropriate temperature. Then, the additive is mixed with 1-15% by weight of the polymer solution, and the mixed solution is coated on the porous polyolefin separator. . The organic solvent is evaporated from the coated mixed solution and the additive is removed with a cleaning agent to obtain a polymer porous membrane having a thickness of 1 to 20 μm.

The additive may be an inorganic material such as silica balls, the diameter of the additive is 0.1 to 20㎛, preferably 1 to 10㎛.

(3) Method by phase separation

The polymer or the polymer and the inorganic material are put into an organic solvent to prepare a 5-30% by weight of the polymer solution at an appropriate temperature, and then the non-solvent is mixed and the mixed solution is coated on the polyolefin separator. The organic solvent is evaporated from the coated mixed solution and the nonsolvent is removed with a cleaning agent to obtain a polymer porous separator coated with a polymer having a thickness of 1 to 20 μm.

The non-solvent is ethylene glycol, 1,2-propanediol, cyclohexanol, 1,4-dioxane, methyl alcohol, ethylene glycol diacetate, ethylene glycol diethyl ether, ethylene glycol monobenzyl ether One, two or more mixtures selected from the group consisting of ethylene glycol monobutyl ether, ethyl glycol glycol monomethyl ether, ethylene glycol phenyl ether, and lauryl alcohol can be used.

As the cleaning agent, one or more mixtures selected from the group consisting of ethanol, methanol, dimethyl ether, diethyl ether, dimethoxyethane, diethoxyethane, dimethyl carbonate, diethyl carbonate and hexane may be used.

2. Preparation of Polymer Electrolyte

The lithium ion polymer electrolyte of the present invention can be obtained by impregnating the porous polymer membrane prepared as described above into a liquid electrolyte containing lithium salt and then gelling it at a temperature of 60-100 ° C. for 10 minutes to 3 hours.

The electrolyte solvent is ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, ethyl methyl carbonate, gamma-butyrolactone gamma-butyrolactone, dimethylsulfoxide, tetrahydrofuran, and mixtures thereof can be used. As the lithium salt, one or more mixtures selected from the group consisting of LiPF ₆ , LiAsF ₆ , LiClO ₄ , LiN (CF ₃ SO ₂ ) ₂ , LiBF ₄ , LiCF ₃ SO ₃ , and LiSbF ₆ may be used. 0.5 M-2 M are preferable.

Hereinafter, the manufacturing process of the battery including the lithium ion polymer electrolyte will be described in more detail.

First step: manufacturing positive and negative plates

The positive electrode plate is prepared by dissolving a mixture of 5% by weight of acetylene black and 3% by weight of PvdF in 92% by weight of the positive electrode active material at 20 to 60 ^° C. in N-methylpyrrolidone.

The positive electrode active material may be composed of one or more selected from the group consisting of LiCoO ₂ , LiMn ₂ O ₄ , LiNiO ₂ , LiNi _1-x Co _x O ₂ , V ₂ O ₅ . As the conductive agent, graphite can be used in addition to acetylene black to exhibit an appropriate effect.

The negative electrode plate is prepared by dissolving 2% by weight of acetylene black and 8% by weight of PvdF in N-methylpyrrolidone at a temperature of 20 to 60 ^° C. in 90% by weight of the negative electrode active material.

The negative electrode active material is composed of one or more selected from graphite, coke, hard carbon and tin oxide. As the conductive agent, graphite can be used in addition to acetylene black to exhibit an appropriate effect.

In the present invention, it may be used as the positive electrode plate and the negative electrode plate itself, or a porous polymer layer having a 1-20 μm thickness and 0.1-20 μm pores may be formed on these electrode plates. In this case, the porous polymer layer is formed by using a low concentration solution in the above-described method for preparing a porous membrane.

Second Step: Preparation of Porous Membrane

It is the same as the manufacturing method of the porous separator described above.

Third Step: Fabrication of Lithium-ion Polymer Battery

FIG. 1 (b) shows a laminated cross-sectional view of the foil 31 to which the negative electrode plate is applied, the negative electrode plate 35, the polymer porous separator 100, the positive electrode plate 45, and the foil 41 to which the positive electrode plate is applied.

1 (c) shows a foil 31 coated with a negative electrode plate, a negative electrode plate 38 having a polymer porous layer 32 formed thereon, a polymer porous separator 100, a positive electrode plate 48 having a polymer porous layer formed thereon, and a foil coated with a positive electrode plate The laminated cross section of 41 is shown.

2 is a process diagram schematically showing a manufacturing process of a lithium ion polymer battery according to the present invention.

The polymer porous separator, the positive electrode plate, the polymer porous separator, and the negative electrode plate are sequentially stacked. Here, the positive electrode plate and the negative electrode plate may be further formed of a polymer porous layer, and when the polymer porous layer is formed on the positive electrode plate and the negative electrode plate, a PE separator may be used instead of the high rich porous membrane. Windings of this laminate about 4-6 times are put in aluminum foil and impregnated with the electrolyte prepared above for 24 hours. Next, the impregnated wound is sealed, the sealed battery is placed in an oven, and then a lithium ion polymer battery is manufactured by gelling at 60-100 ^° C. for 1-48 hours.

When the wound is impregnated with the electrolyte, the electrolyte flows into the porous polymer membrane and the electrode plate. In the porous polymer membrane, the gel is absorbed into the pores of the gel-forming polymer and the polyolefin separator. When the porous polymer layer is coated on the electrode plate, the electrode plate is absorbed into the pores of the porous gel-forming polymer layer. In the gelation process, the gel-forming polymer of the electrolyte and the electrode layer is gelled together with the electrolyte solution. If the gelation process is not carried out, the electrolyte in the pores present in the polyolefin or the gel-forming polymer may leak to the outside, but after the gelation process, the gel-forming polymer adheres to the electrode. Play the role of evangelism. The gelation time in the gelation process It is about 500-600mAh class battery. If it is less than 1 hour, complete gelation is not performed, resulting in insufficient adhesiveness and separation of liquid phase and polymer phase. If the gelation time is too long, energy consumption is high, and the time needs to be properly adjusted according to the battery system. Therefore, the preferred gelation time in the present invention was 5 to 12 hours.

Although the present invention is described in detail by the following examples, these examples are merely illustrative of the present invention and the invention is not limited thereto.

Example 1

After mixing 10 g of electrolyte solution (1M LiPF ₆ in EC / DEC), 1 g of polyvinylidene fluoride, and hexafluoropropylene copolymer (PvdF-HFP) for 12 hours, 100 mg of this mixed solution was placed in a 6 x 6 cm ² aluminum pouch. Placed in a bag and sealed. One sealed sample was stored in an 80 ^° C. oven and one was stored inside at room temperature for 10 hours to check inside. The solution stored at 80 ^o C showed gelation to form a film, and the solution stored at room temperature remained in solution.

SEM image was taken by drying in the same manner as described above to determine the polymer component present in the gelation, but dried by gelling the porous PE film in a mixed solution for 1 minute as shown in FIG. It can be seen that a film with large pores is formed on the PE film.

Example 2

Polyvinylidene fluoride as a polymer component and 3.5 g of hexafluoropropylene copolymer (PvdF-HFP) were mixed with 100 g of tetrahydrofuran as an organic solvent at room temperature for 12 hours. The mixed solution was passed through a porous PE membrane of 9 ㎛. Pass the separator from room temperature 60^oC It was dried between, the thickness of the separator thus prepared was 20㎛. Figure 4 (a) is a SEM photograph of the polymer porous separator can be seen that the polymer is covered with pores of about 10㎛ size. Polymer porous membrane 2 × 2 cm²After cutting to the area of impregnated liquid and 80^oGelled at C for 5 hours. The ion conductivity measured at this time is 1.2 × 0^-3S / cm.

Example 3

In the same manner as in Example 2, but the amount of the polymer 2g, 5g Only 2 wt% and 5 wt% of the mixed solution was passed through a 9 μm porous PE separator. Pass the separator from room temperature 60^oC It was dried between, the total thickness of the membrane thus prepared was 12㎛, 25㎛. It can be seen in FIG. 5 (a) that the polymer amount is 2% by weight and the polymer layer is partially scattered. The polymer amount is 5% by weight. It can be seen in Figure 5 (b) formed. Polymer porous membrane 2 × 2cm²After cutting to the area of impregnated liquid and 80^oGelled at C for 5 hours. The ionic conductivity measured at this time is 1.23 × 10 for 2 wt% and 5 wt% of the polymer, respectively.^-3, 1.17 × 10^-3S / cm.

Example 5

To 100 g of an organic solvent, tetrahydrofuran, 3.5 g of polyvinylidene fluoride and hexafluoropropylene copolymer (PvdF-HFP) and 0.35 g of fine silica of 7 nm particle size were added and mixed at room temperature for 12 hours. The mixed solution was passed through a porous PE membrane of 9㎛. Pass the separator from room temperature 60^oDry between C temperatures. The total thickness of the separator thus prepared was 20 μm. As can be seen in Figure 6 the polymer is 5-10㎛ It can be seen that it is covered with pores of size and microsilica is distributed in the pores. 2 × 2cm molecular porous membrane²After cutting to the area of impregnated liquid and 80^oGelled at C for 5 hours. The ion conductivity measured at this time is 1.25 × 10^-3S / cm.

Example 6

The ion conductivity of the polymer porous membrane, which was the same as that of Example 2 but was impregnated with the electrolyte and not subjected to the gelation process, was 1.12 × 10 ⁻³ S / cm, which was almost the same as that of Example 2. The reason for having almost the same ionic conductivity is that as shown in the SEM photograph of FIG. 4 (a) of the polymer porous separator, the large pores are formed, so that the electrolyte solution is impregnated into the pores to become the main path of ion conduction.

Example 7

The same procedure as in Example 2, but the ion conductivity measured for the polymer porous separator prepared by mixing the polymer solution at 50 ^o C for 12 hours was 1.1 × 10 ^-3 S / cm and the SEM picture is shown in FIG.

Example 8

Polyvinylidene fluoride, a hexafluoropropylene copolymer (PvdF-HFP), 20 g of polyvinylidene fluoride (PvdF-HFP), and 10 g of silica ball, each having a mean diameter of 1 μm, were mixed with 100 g of tetrahydrofuran as an organic solvent at 50 ^° C. for 12 hours. The mixed solution was coated on a 9 μm porous PE membrane. After the coated separator is dried between room temperature and 60 ^° C temperature, silica balls are removed for 10 hours in a hydrofluoric acid solution at a predetermined concentration. The separator from which the silica balls were removed was washed in ultrapure water and dried at 50 ^° C. for 24 hours. After cutting the polymer porous membrane into an area of 2 × 2 cm ^2, the liquid was impregnated and gelled at 80 ^° C. for 5 hours. The ion conductivity measured at this time was 1.15 × 10 ⁻³ S / cm.

Example 9

To prepare a porous separator using phase separation, 10 g of PvdF and 20 g of ethylene glycol were mixed at 50 ^° C. for 12 hours to 100 g of tetrahydrofuran. This mixed solution was coated on a 9 μm porous PE separator using a doctor blade. The coated separator was dried at room temperature from 60 ^o C, washed with ethanol to remove ethylene glycol as a non-solvent, and re-dried at 60 ^o C for 12 hours to prepare a porous material. FIG. 8 shows the surface of the polymer porous separator with a scanning electron microscope, and it can be seen that the polymer layer is formed with large pores of 5-10 μm. After cutting the polymer porous membrane into an area of 2 × 2 cm ^2, the liquid was impregnated and gelled at 80 ^° C. for 5 hours. The ion conductivity measured at this time was 1.25 × 10 ⁻³ S / cm.

Example 10

Polyvinylidene fluoride as a polymer component and 3.5 g of hexafluoropropylene copolymer (PvdF-HFP) were mixed with 100 g of tetrahydrofuran as an organic solvent at room temperature for 12 hours. The mixed solution was passed through a porous PE membrane of 9 ㎛. Passed separator was dried from room temperature to 60 ^° C. The polymer porous separator thus formed was laminated and wound in the order of the polymer porous separator, the positive electrode plate, the polymer porous separator, and the negative electrode plate. The wound was placed in aluminum foil and impregnated with electrolyte (1M LiPF ₆ in EC / DEC) for 24 hours. Next, the impregnated wound was sealed, and the sealed cell formation was placed in an oven, and then a lithium ion polymer battery was manufactured by gelling at 80 ^° C. for 5 hours. 9 shows high-rate discharge characteristics of the battery prepared in Example 10, wherein the high-rate discharge characteristics are charged at a constant current / constant voltage at 0.5C, the discharge capacity for each discharge rate is measured, and as a ratio to the 0.2C discharge capacity. Indicated. It can be seen that when the discharge at 3C has a capacity of 95% of the 0.2C discharge. The high rate discharge characteristics are excellent because the ion conductivity of the electrolyte is good and the adhesion to the electrode of the gelling polymer is good, thereby reducing the internal resistance.

Example 11

A lithium ion polymer battery was prepared in the same manner as in Example 10 except that only 2 g and 5 g of the polymer component in the solution was changed. Cycle characteristics and discharge capacity characteristics of the cell are shown in FIGS. 10 (a) and 10 (b). 25^oAt the test temperature of C, the discharge capacity was measured with a cycle characteristic of 1C and a capacity characteristic of 0.2C. In the discharge capacity characteristics, the discharge capacity is expressed as the capacity per positive electrode active material, and the discharge capacity in the cycle characteristic is expressed as a ratio with respect to the discharge capacity in the first cycle. The more the polymer component is included, the cycle characteristics are improved, but the discharge capacity is slightly smaller.

Example 12

Polyvinylidene fluoride as a polymer component and 3.5 g of hexafluoropropylene copolymer (PvdF-HFP) were mixed with 100 g of tetrahydrofuran as an organic solvent at 50 ^° C. for 12 hours. A 9 μm porous PE separator was passed through the mixed solution. Passed separator was dried from room temperature to 60 ^° C. The polymer porous separator thus formed was laminated with a polymer porous separator, a positive electrode plate, a polymer porous separator, and a negative electrode in sequence, and the wound wound was placed in an aluminum foil and impregnated with an electrolyte solution (1M LiPF ₆ in EC / DEC) for 24 hours. Next, the impregnated wound was sealed, and the sealed cell formation was placed in an oven, and then a lithium ion polymer battery was manufactured by gelling at 80 ^° C. for 5 hours. At this time, the discharge capacity characteristics of the manufactured cell are shown in FIG. 11. The discharge capacity was measured at 0.2 C at a test temperature of 25 ^° C., and the discharge capacity was expressed as capacity per positive electrode active material. The discharge capacity is almost the same as that of the lithium ion polymer battery prepared in Example 10.

Example 13

100 g of tetrahydrofuran, an organic solvent, 3.5 g of polyvinylidene fluoride and hexafluoropropylene copolymer (PvdF-HFP) and fumed silica of 7 nm particle size 0.35 g was added and mixed at room temperature for 12 hours. The mixed solution was passed through a porous PE membrane of 9㎛. Pass the separator from room temperature 60^oDry between C temperatures. The polymer porous separator thus formed was laminated and wound in the order of the polymer porous separator, the positive electrode plate, the polymer porous separator, and the negative electrode plate. The wound is placed in aluminum foil and the electrolyte (1M LiPF)₆in EC / DEC) for 24 hours. Next, the impregnated windings are sealed, the sealed cell formation is placed in an oven, and then 80^oA lithium ion polymer battery was prepared by performing a gelation process at 5 hours in C. In this case, the discharge capacity of the manufactured cell is as shown in FIG. 12, and the discharge capacity is expressed as a capacity per positive electrode active material. 25^oThe discharge capacity was measured at 0.2 C at a test temperature of C. The discharge capacity is almost the same as that of the lithium ion polymer battery prepared in Example 10.

Example 14

A lithium ion polymer battery was prepared in the same manner as in Example 10, except that the cathode and anode plates were Only the formation of the porous polymer layer is different. Polyvinylidene fluoride as a polymer component and 2 g of hexafluoropropylene copolymer (PvdF-HFP) were mixed with 100 g of tetrahydrofuran as an organic solvent at room temperature for 12 hours. The positive electrode plate and the negative electrode plate used in Example 10 were passed through the mixed solution to form a porous polymer layer on the positive electrode plate and the negative electrode plate. The anode and cathode plates on which the porous polymer layer was formed were heated from room temperature to 60 degrees.^oDry between C temperatures. The thickness of the coated porous polymer layer was 3 μm and 5 μm, respectively. 25^oThe discharge capacity of the battery manufactured at 1 C at the test temperature of C was measured, and the cycle characteristics were expressed as a ratio with respect to the discharge capacity in the first cycle.

Comparative Example 1

A lithium ion battery prepared using only a porous PE separator containing no polymer was prepared. In the lithium ion battery cell manufactured, the discharge capacity was measured at a cycle temperature of 1 C and a capacity characteristic of 0.2 C at a test temperature of 25 ^° C.

Comparative Example 2

A lithium ion polymer battery was prepared in the same manner as in Example 10, but without gelation. At the test temperature of 25 ^o C, the cycle capacity was 1C and the discharge capacity was measured at 0.2C.

Looking at the characteristics of the lithium ion polymer battery according to the present invention through the above Examples and Comparative Examples are as follows.

Figure 4 (a) is a SEM photograph of the porous polymer membrane prepared in Example 2, Figure 4 (b) is a SEM photograph of the porous PE separator used in the present invention. It can be seen that the polymeric porous membrane has large pores of about 10 μm.

13 (a) and 13 (b) show the cell cycle characteristics and the discharge capacity of the lithium ion battery prepared using the porous PE separator of Comparative Example 1 and the lithium ion polymer battery according to Example 10. In the discharge capacity characteristics, the discharge capacity is expressed as the capacity per positive electrode active material, and the discharge capacity in the cycle characteristic is expressed as a ratio with respect to the discharge capacity in the first cycle. Prepared using the porous PE separator of Comparative Example 1 Compared with lithium ions, the capacity of the lithium ion polymer battery according to Example 10 was slightly reduced, but the cycle characteristics were improved.

14 (a) and 14 (b) show a lithium ion polymer battery using a polymer electrolyte of Comparative Example 2 and Example 10 Cell cycle characteristics and discharge capacity of a lithium ion polymer battery. In the discharge capacity characteristics, the discharge capacity is expressed as the capacity per positive electrode active material, and the discharge capacity in the cycle characteristic is expressed as a ratio with respect to the discharge capacity in the first cycle. It can be seen that the lithium ion polymer battery prepared by the polymer electrolyte of Comparative Example 2, which was not gelled, had a slightly higher discharge capacity than the gelated lithium ion polymer battery, but the cycle characteristics were not so good.

FIG. 15 compares Example 10 with Example 13 and compares the addition of the inorganic material with the addition of the inorganic material. Cycle characteristics were measured by repeating charging and discharging at 25C at 1C. It can be seen that the cycle is improved when the inorganic material is added, which increases the electrolytic solution containing capacity and retention ability of the gelled polymer due to the addition of inorganic material. help Because of giving.

FIG. 16 compares Example 10 with Example 14 in which a polymer porous layer is coated on a positive electrode plate and a negative electrode plate, and the cycle characteristics are improved by coating the polymer porous layer on an electrode.

As described above, the lithium ion polymer electrolyte of the present invention is coated with a polymer having a large pore on the polyolefin membrane to transfer ions through the liquid phase and the gel phase, so that the ion conductivity is high and the adhesion with the electrode is excellent after gelation. And reduce interfacial resistance. The lithium ion polymer battery using the electrolyte has a simple manufacturing process and excellent performance such as high rate characteristics and cycle characteristics.

Claims (23)

In the method for producing a lithium ion polymer electrolyte, Preparing a polymer solution of 1-20% by weight by adding an organic solvent to the polymer compound at a temperature of room temperature to 60 ° C; Preparing a coated separator by passing a polyolefin-based separator through the polymer solution; Preparing a polymer porous separator by drying the coated separator at a temperature of room temperature to 60 ° C .; Impregnating the polymer porous separator into a liquid electrolyte solution containing lithium salts; And Method of producing a lithium ion polymer electrolyte comprising the step of gelling the impregnated polymer porous separator at a temperature of 60-100 ℃ 20 minutes to 3 hours. The method of claim 1, The polyolefin-based separator is any one selected from the group consisting of a PE separator, a PP separator, and a multilayer separator of PE and PP. The method of claim 1, The polymer solution manufacturing step of producing a lithium ion polymer electrolyte, characterized in that further comprising an inorganic material in the polymer compound. The method of claim 3, The inorganic material is any one selected from the group consisting of SiO ₂ , TiO ₂ , ZrO ₂ , Al ₂ O ₃ , BaTiO ₃ , Bi ₂ O ₃ , Fe ₂ O ₃ , CaSiO ₃ , and PbTiO ₃ Method for producing a polymer electrolyte. The method according to any one of claims 1 to 4, The polymer porous separator is a method of producing a lithium ion polymer electrolyte, characterized in that it has a pore of 0.1 to 20㎛. In the method for producing a lithium ion polymer electrolyte, Preparing a polymer solution of 5-30% by weight by adding an organic solvent to the polymer compound at a temperature of room temperature to 60 ° C; Mixing an additive with the polymer solution to form a binder solution; Passing the polyolefin-based separator through the binder solution to form a coated separator; Drying the coated separator at a temperature of room temperature to 60 ° C .; Preparing the polymer porous separator by removing the additive from the dried separator; Impregnating the polymer porous separator into a liquid electrolyte solution containing lithium salts; And Method of producing a lithium ion polymer electrolyte comprising the step of gelling the impregnated polymer porous separator at a temperature of 60-100 ℃ 20 minutes to 3 hours. The method of claim 6, The additive is a method of producing a lithium ion polymer electrolyte, characterized in that it comprises a mineral of silica ball. The method of claim 6, The additive is a method for producing a lithium ion polymer electrolyte, characterized in that mixed in 1 to 15% by weight of the polymer solution. The method according to any one of claims 6 to 8, The polymer porous separator is a method of producing a lithium ion polymer electrolyte, characterized in that it has a pore of 0.1 to 20㎛. In the method for producing a lithium ion polymer electrolyte, Preparing a polymer solution of 5-30% by weight by adding an organic solvent to the polymer compound at a temperature of room temperature to 60 ° C; In the polymer solution Mixing the non-solvent and passing the poly-olipine-based separator to form a coated separator; Drying the coated separator at a temperature of room temperature to 60 ° C .; And And removing the non-solvent in the dried coating separator with a detergent to prepare a polymer porous separator. The method of claim 10, The polymer solution manufacturing step of producing a lithium ion polymer electrolyte, characterized in that further comprising an inorganic material in the polymer compound. The method of claim 11, The nonsolvent is ethylene glycol, 1,2-propanediol, cyclohexanol, 1,4-dioxane, methyl alcohol, ethylene glycol diacetate, ethylene glycol diethyl ether, ethylene glycol monobenzyl ether A method for producing a lithium ion polymer electrolyte, characterized in that one or more mixtures selected from the group consisting of ethylene glycol monobutyl ether, ethyl glycol glycol methyl methyl, ethylene glycol phenyl ether, and lauryl alcohol. The method of claim 11, The cleaning agent is a lithium ion polymer electrolyte characterized by one or more mixtures selected from the group consisting of ethanol, methanol, dimethyl ether, diethyl ether, dimethoxyethane, diethoxyethane, dimethyl carbonate, diethyl carbonate and hexane Method of preparation. The method according to any one of claims 10 to 13, The polymer porous separator is a method of producing a lithium ion polymer electrolyte, characterized in that it has a pore of 0.1 to 20㎛. In the manufacturing method of a lithium ion polymer battery, Manufacturing a positive plate and a negative plate; Preparing a polymer solution of 1-20% by weight by adding an organic solvent to the polymer compound at a temperature of room temperature to 60 ° C; Preparing a polymer porous separator by passing a polyolefin-based separator through the polymer solution; Sequentially stacking the polymer porous separator, the positive electrode plate, the polymer porous separator, and the negative electrode plate to form a first laminate; Cutting the first stack to a predetermined size and stacking the stack according to a stacking direction to form a second stack or winding the first stack to form a wound; Impregnating the second stack or the wound material with a liquid electrolyte containing lithium salt; And Sealing the impregnated material and manufacturing the lithium ion polymer battery, comprising the step of gelling at 60 to 100 ° C. for 1-24 hours. The method of claim 15, The polymer solution manufacturing step is a method of manufacturing a lithium ion polymer battery, characterized in that it further comprises an inorganic material in the polymer compound. The method of claim 15, Preparing the positive plate and the negative plate Preparing a polymer solution of 1-20% by weight by adding an organic solvent to the polymer compound at a temperature of room temperature to 60 ° C; Manufacturing a positive electrode plate having a polymer porous layer by passing the positive electrode plate through the polymer solution; And The method of manufacturing a lithium ion polymer battery further comprises the step of passing the negative electrode plate through the polymer solution to prepare a negative electrode plate having a polymer porous layer formed thereon. In the manufacturing method of a lithium ion polymer battery, Manufacturing a positive plate and a negative plate; Preparing a polymer solution of 5-30% by weight by adding an organic solvent to the polymer compound at a temperature of room temperature to 60 ° C; Mixing an additive with the polymer solution to form a binder solution; Passing the polyolefin-based separator through the binder solution to form a coated separator; Drying the coated separator at a temperature of room temperature to 60 ° C .; Preparing the polymer porous separator by removing the additive from the dried separator; Sequentially stacking the polymer porous separator, the positive electrode plate, the polymer porous separator, and the negative electrode plate to form a first laminate; Cutting the first stack to a predetermined size and stacking the stack according to a stacking direction to form a second stack or winding the first stack to form a wound; Impregnating the second stack or the wound material with a liquid electrolyte containing lithium salt; And Sealing the impregnated material and manufacturing the lithium ion polymer battery, comprising the step of gelling at 60 to 100 ° C. for 1-24 hours. The method of claim 18, Preparing the positive plate and the negative plate Preparing a polymer solution of 1-20% by weight by adding an organic solvent to the polymer compound at a temperature of room temperature to 60 ° C; Manufacturing a positive electrode plate having a polymer porous layer by passing the positive electrode plate through the polymer solution; And The method of manufacturing a lithium ion polymer battery further comprises the step of passing the negative electrode plate through the polymer solution to prepare a negative electrode plate having a polymer porous layer formed thereon. In the manufacturing method of a lithium ion polymer battery, Manufacturing a positive plate and a negative plate; Preparing a polymer solution of 5-30% by weight by adding an organic solvent to the polymer compound at a temperature of room temperature to 60 ° C; In the polymer solution Mixing the non-solvent and passing the poly-olipine-based separator to form a coated separator; Drying the coated separator at a temperature of room temperature to 60 ° C .; Preparing a polymer porous separator by removing the non-solvent in the dried coating separator with a detergent Sequentially stacking the polymer porous separator, the positive electrode plate, the polymer porous separator, and the negative electrode plate to form a first laminate; Cutting the first stack to a predetermined size and stacking the stack according to a stacking direction to form a second stack or winding the first stack to form a wound; Impregnating the second stack or the wound material with a liquid electrolyte containing lithium salt; And Sealing the impregnated material and manufacturing the lithium ion polymer battery, comprising the step of gelling at 60 to 100 ° C. for 1-24 hours. The method of claim 20, The polymer solution manufacturing step is a method of manufacturing a lithium ion polymer battery, characterized in that it further comprises an inorganic material in the polymer compound. The method of claim 20, Preparing the positive plate and the negative plate Preparing a polymer solution of 1-20% by weight by adding an organic solvent to the polymer compound at a temperature of room temperature to 60 ° C; Manufacturing a positive electrode plate having a polymer porous layer by passing the positive electrode plate through the polymer solution; And The method of manufacturing a lithium ion polymer battery further comprises the step of passing the negative electrode plate through the polymer solution to prepare a negative electrode plate having a polymer porous layer formed thereon. In the manufacturing method of a lithium ion polymer battery, Manufacturing a positive plate and a negative plate; Preparing a polymer solution of 1-20% by weight by adding an organic solvent to the polymer compound at a temperature of room temperature to 60 ° C; Manufacturing a positive electrode plate having a polymer porous layer by passing the positive electrode plate through the polymer solution; Manufacturing a negative electrode plate on which a polymer porous layer is formed by passing the negative electrode plate through the polymer solution; Forming a first laminate by sequentially stacking the positive electrode plate on which the polymer porous layer is formed, the polyolefin-based separator, and the negative electrode plate on which the polymer porous layer is formed; Cutting the first stack to a predetermined size and stacking the stack according to a stacking direction to form a second stack or winding the first stack to form a wound; Impregnating the second stack or the wound material with a liquid electrolyte containing lithium salt; And Sealing the impregnated material and manufacturing the lithium ion polymer battery, comprising the step of gelling at 60 to 100 ° C. for 1-24 hours.