JP2000208142A - Production of nonaqueous electrolyte secondary battery electrode and nonaqueous electrolyte battery using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the non-poring of a porous polymer electrolytic film layer formed on the surface of an electrode to enhance charging/discharging performance by including a polymer solution obtained by dissolving a polymer wetting or swelling by an electrolyte to a solvent in the electrode to press an electrode body, and then extracting the solvent. SOLUTION: A paste consisting of a mixture of lithium nickel, acetylene black, vinylidene fluoride/hexafluoropropylene copolymer P(VdF/HFP), and NMP is applied to both sides of an aluminum foil followed by drying to prepare a positive electrode body. A polymer solution is prepared by dissolving the P(VdF/HFP) to NMP, and the positive electrode body is dipped in the polymer solution to include the polymer solution in the positive electrode body. The positive electrode body containing the polymer solution is pressed. The positive electrode body having the polymer solution adhered to the surface is dipped in a mixed solution of water and methanol to extract NMP, whereby a positive electrode having porous polymer electrolyte is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-aqueous electrolyte secondary battery.

[0002]

2. Description of the Related Art Conventionally, a solvent extraction method is used for manufacturing an electrode provided with a porous polymer electrolyte. In the solvent extraction method, a polymer solution a ′ obtained by dissolving a polymer in a solvent a is
The solvent a is extracted by being immersed in the solvent b, and the portion from which the solvent a is removed becomes a pore to obtain a porous polymer.

[0003] An electrode with a porous polymer electrolyte is fabricated as follows. First, a paste containing an active material is applied on a current collector and dried to manufacture an electrode body in which the active material is formed integrally with the current collector. The porosity of the electrode body thus manufactured is usually about 50 to 60%. Next, the electrode body is immersed in a polymer solution a ′ in which a polymer having a property of being wetted or swelled by an electrolytic solution is dissolved in a solvent a, and the polymer solution a ′ is uniformly formed in pores in a mixture layer of the electrode body. Infiltrate. Next, when the electrode body containing the polymer solution a ′ is immersed in the solvent b, the solvent a in which the polymer is dissolved is compatible with the solvent b.
Is extracted by the solvent b, and the polymer is solidified in a state where the portion from which the solvent a is removed becomes a hole. By this step, an electrode body having a porous polymer uniformly in the pores in the positive electrode mixture layer can be obtained. Next, by drying, water or the like adhering to the electrode is removed, and finally, the electrode is pressed to have a current collecting property, and the porosity of the electrode is reduced to about 30%.

[0004]

When the electrode is provided with a porous polymer electrolyte using the above-mentioned solvent extraction method, the following problems occur. If the polymer solution a ′ in which the polymer attached to the electrode surface is dissolved before the solvent extraction cannot be completely removed,
A porous polymer electrolyte layer is formed on the electrode surface. In particular, when the viscosity of the polymer solution is high, it is difficult to completely remove the polymer solution a ′ attached to the electrode surface, and a porous polymer electrolyte layer is formed on the electrode surface.
When the electrode is provided with a porous polymer electrolyte and then pressed to give the electrode a current collecting property, the pores of the porous polymer electrolyte layer formed on the electrode surface disappear and the non-porous polymer electrolyte layer becomes Therefore, there is a problem that the charge / discharge performance of the battery is deteriorated because the movement path of lithium ions is hindered.

[0005]

Various studies have been made to solve the above-mentioned problems, and it has been found that the following electrode manufacturing method is effective. The electrode manufacturing process according to the present invention includes a first step of applying a paste containing an active material, a conductive agent, and a binder on a current collector, and drying the electrode body to produce an electrode body. A second step of including a polymer solution a ′ in which a polymer having a property of being wet or swelling by the electrolytic solution is dissolved in a solvent a, and a third step of pressing an electrode body including the polymer solution a ′; The solvent a of the polymer solution a ′ contained in the electrode body,
A fourth step comprises extracting with a solvent b compatible with the solvent a and providing a porous polymer electrolyte in the pores and on the surface of the electrode. In this manufacturing process, after the electrode body is pressed to make the electrode current-collecting, solvent extraction is performed, so that even if a porous polymer electrolyte layer is formed on the electrode surface, the porous polymer electrolyte There is no risk that the holes in the layer will disappear.

The following electrode manufacturing method is also effective for solving the above-mentioned problems. First, a first step of applying and drying a paste containing an active material, a conductive agent, and a binder on a current collector to manufacture an electrode, and pressing the electrode body to give the electrode a current collecting property A second step, a third step of including, in the electrode, a polymer solution a ′ obtained by dissolving a polymer having a property of being wetted or swelling by the electrolyte in a solvent a, solvent b compatible with a
And a fourth step of providing the electrode with a porous polymer electrolyte. . Also in this manufacturing method, there is no possibility that the pores of the porous polymer electrolyte layer formed on the electrode surface disappear.

Further, in any of the above methods, after the electrode is pressed to have current collecting properties, the solvent extraction treatment is performed, so that the polymer solution a ′ attached to the electrode surface is formed to a predetermined thickness. Since the porous polymer electrolyte membrane formed on the electrode surface can be used as a separator, which leads to a reduction in the number of battery manufacturing steps, the electrode manufacturing method of the present invention is a very useful method.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below.
Will be described in more detail. Positive used in the present invention
The pole active material is a compound that can store and release lithium.
There is no particular limitation as long as it is present.
i_xMO_TwoOr Li_yM_TwoO_Four(However, M is transition gold
Genus, 0 ≦ x ≦ 1, 0 ≦ y ≦ 2), or Li_xM_yN_{1 - y}O_Two
(However, M is a transition metal, N is a metal, and P, B, F
0 ≦ x containing one or more elements selected from the group consisting of
≦ 1, 0 ≦ y ≦ 1) complex oxide, tunnel-like
Oxides with pores, metal chalcogenides with a layered structure
Can be used. As a specific example, LiCoO
_Two, LiNiO_Two, LiMn_TwoO_Four, Li_TwoMn_TwoO_Four, Li
Ni_0.5Co_0.5O_Two, LiNi_0.8Co_0.17Al_0.03O_Two,
LiNi_{0 .8}Co_0.17B_0.03O_Two, MnO_Two, FeO_Two, V_Two
O_Five, V₆O₁₃, TiO_Two, TiS_TwoAnd the like. Ma
In addition, examples of organic compounds include compounds such as polyaniline.
And an electrically conductive polymer. In addition, inorganic compounds,
Regardless of the compound, the above various active materials may be used as a mixture.
No.

As the negative electrode active material, for example, Al, Si,
Alloy of lithium with Pb, Sn, Zn, Cd, etc., LiF
Transition metal composite oxides such as e ₂ O ₃ ; transition metal oxides such as WO ₂ and MoO _2; carbonaceous materials such as graphite and carbon; lithium nitride such as Li ₅ (Li ₃ N); And mixtures thereof.

As the polymer provided on the electrode, a polymer having flexibility capable of changing the shape following the volume expansion and contraction of the active material due to charge and discharge is preferable, and a gel-like ionic conductive polymer obtained by swelling the polymer with an electrolyte solution. It is better to use Specifically, polyvinylidene fluoride (PVd
F) / hexafluoropropylene (HFP) copolymer,
Polyether such as polyvinylidene fluoride, hexafluoropropylene, polyvinyl chloride, polyacrylonitrile, polyethylene oxide, polypropylene oxide, polyacrylonitrile, polyvinylidene fluoride, polyvinylidene chloride, polymethyl methacrylate,
Polymethyl acrylate, polyvinyl alcohol, polymethacrylonitrile, polyvinyl acetate, polyvinyl pyrrolidone, polyethylene imine, polybutadiene,
Polystyrene, polyisoprene, or these inducers can be used alone or as a mixture.
Further, a polymer obtained by copolymerizing various monomers constituting the above polymer can also be used.

The electrode according to the present invention comprises a lithium ion conductive porous polymer electrolyte produced by a solvent extraction method. Solvent a that dissolves polymer in solvent extraction method
As, dimethylformamide, propylene carbonate, ethylene carbonate, dimethyl carbonate,
Dicarbonate, carbonates such as ethyl methyl carbonate, dimethyl ether, diethyl ether,
Solvents that dissolve ethers such as ethyl methyl ether and tetrahydrofuran, and polymers such as dimethylacetamide, 1-methyl-pyrrolidinone, and n-methyl-2-pyrrolidone.

The extraction solvent b may be compatible with the solvent a, and may be water, alcohol, acetone or the like, or a mixture thereof. Examples of the alcohol include methanol, ethanol, 1-propanol, 2-propanol and the like, or a mixture thereof.

A positive electrode provided with a porous polymer electrolyte is manufactured by the following steps. In the first step, a paste is prepared by kneading a positive electrode active material, a conductive auxiliary such as acetylene black, and a binder, and the paste is applied to a current collector such as an aluminum thin plate and dried to form a positive electrode. Build the body. In the second step, the positive electrode main body is immersed in a polymer solution a ′ in which the polymer is dissolved in a solvent a, or the positive electrode main body is made to contain the solvent a in which the polymer is dissolved by using a vacuum impregnation method or the like. In the third step, the positive electrode body containing the polymer solution a 'is pressed. It is preferable that the porosity of the positive electrode body obtained by removing the polymer solution a ′ of the positive electrode body thus obtained is 50% or less.

In the fourth step, the polymer solution a ′ attached to the surface of the positive electrode body is made to have a predetermined thickness, and then immersed in an extraction solvent b, whereby the solvent a is extracted, and the solvent a is extracted. The polymer is solidified in a state in which the removed portion becomes a hole, and a positive electrode plate is formed in which the porous polymer electrolyte having three-dimensionally communicating holes is uniformly distributed in the holes in the positive electrode mixture layer. You. Finally, the positive electrode plate is dried, and water and the like existing on the positive electrode surface are removed, thereby completing the positive electrode provided with the porous polymer electrolyte according to the present invention.

In the first step, a paste obtained by kneading an active material and a binder is applied to a current collector such as a copper thin plate in the first step and dried to produce a negative electrode body. The following is manufactured through the same steps as the positive electrode.

Further, the following method can be cited as a method for producing an electrode provided with a porous polymer. In the first step,
A paste obtained by kneading a positive electrode active material particle, a conductive auxiliary such as acetylene black, and a binder is applied to a current collector such as an aluminum thin plate and dried to form a positive electrode body.
The positive electrode body is pressed in the step of
% Or less.

In the third step, the positive electrode main body is immersed in a polymer solution a 'in which a polymer is dissolved in a solvent a, or the positive electrode main body is made to contain the polymer solution a' by a vacuum impregnation method. After the thickness of the polymer solution a ′ attached to the positive electrode surface was set to a predetermined thickness, the positive electrode body was immersed in the extraction solvent b, and the portion of the polymer solution a ′ from which the solvent a was removed became a hole. Thus, the polymer is solidified, and a positive electrode plate is formed in which the porous polymer electrolyte having three-dimensionally communicating holes is uniformly distributed in the holes in the positive electrode mixture layer. Finally, the positive electrode is dried to evaporate water etc. existing on the positive electrode surface,
A positive electrode provided with the porous polymer electrolyte according to the present invention is completed.

In the first step, the paste obtained by kneading the negative electrode active material particles and the binder is applied to a current collector such as a copper thin plate and dried in the first step to produce a negative electrode body. The following steps are manufactured through the same process as the positive electrode.

The positive electrode and the negative electrode thus manufactured are arranged in a battery case with a separator interposed therebetween, or in a case where a porous polymer electrolyte membrane on the electrode surface is used as a separator, no separator is interposed. To place. When the electrolyte for the lithium secondary battery is injected, the electrolyte enters the pores of the electrode mixture, swells the polymer provided in the pores of the electrode mixture, and the polymer becomes a gel. At the same time, the electrolyte enters the pores of the polymer, resulting in a lithium ion conductive porous polymer electrolyte in which the electrolyte is present in the pores of the polymer. Thus, the non-aqueous electrolyte secondary battery according to the present invention is completed. Further, the positive electrode and the negative electrode may be composed of a combination of the above two types of electrode production methods.

Examples of the electrolyte solvent include a mixed solvent of ethylene carbonate and diethyl carbonate, ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, γ-butyrolactone, sulfolane, dimethyl sulfoxide, acetonitrile, dimethylformamide, dimethylacetamide, and the like.
A polar solvent such as 1,2-dimethoxyethane, 1,2-diethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, dioxolan, methyl acetate, or a mixture thereof may be used.

Further, as the salt to be contained in the electrolytic solution,
LiPF₆, LiBF_Four, LiAsF ₆, LiClO_Four, L
iSCN, LiI, LiCF_ThreeSO_Three, LiCl, LiB
r, LiCF_ThreeCO_TwoLithium salts such as
Mixtures may be used, and the concentration may vary depending on the combination of solvent and salt.
Therefore, the optimum value may be set.

As the separator, a polypropylene microporous membrane, a polyethylene microporous membrane, or a separator composed of a polymer constituting the porous polymer electrolyte may be used.

Next, embodiments of the nonaqueous electrolyte secondary battery according to the present invention will be described in more detail. Embodiment 1 As a preferred embodiment of the present invention, lithium nickel oxide is used as a positive electrode active material, graphite is used as a negative electrode active material, and vinylidene fluoride / hexafluoropropylene copolymer (P) is used as a material of a porous polymer electrolyte.
(VdF / HFP)) will be described.

First, the manufacturing process of the positive electrode will be described. Lithium nickelate 66.8 wt%, acetylene black 1.4 wt%, P (VDF / HFP) 2.8 wt%, N
A paste mixed with 29 wt% of MP was applied to both sides of an aluminum foil having a width of 20 mm, a length of 480 mm and a thickness of 20 μm, dried at 90 ° C. to evaporate NMP, thereby preparing a positive electrode body.

Next, 20 wt% of P (VdF /
HFP) was dissolved in the polymer solution, and the positive electrode body was immersed in the polymer solution, so that the positive electrode body contained the polymer solution. Here, NMP corresponds to the solvent a, and NMP
A polymer solution in which 20% by weight of P (VdF / HFP) is dissolved corresponds to a polymer solution a ′. Next, the positive electrode body containing the polymer solution was pressed. The thickness of the positive electrode body excluding the polymer solution was 160 μm, and the porosity was 3 μm.
It was 0%.

Next, the thickness of the polymer solution attached to the positive electrode surface was set to 45 μm, and the positive electrode body was immersed in a mixed solvent of 25 wt% of water and 75 wt% of methanol to extract NMP. The thickness of the porous polymer electrolyte membrane formed on the positive electrode surface was 15 μm. Here, water 25 wt%
And a mixed solvent of methanol and 75 wt% corresponds to the solvent b. Next, the electrode was dried at 130 ° C. for 30 minutes to remove water and the like attached to the electrode, thereby obtaining a positive electrode provided with the porous polymer electrolyte according to the present invention. The total weight of the active material and the conductive additive filled per unit area was 21 mg / cm ² .

Next, the steps of manufacturing the negative electrode will be described.
Graphite 81wt%, P (VdF / HFP) 9w
t, NMP 10 wt% mixed paste, thickness 14
It was applied to both sides of a copper foil of μm and dried at 90 ° C. to evaporate NMP, thereby preparing a negative electrode body.

Next, 20 wt% of P (VdF /
A polymer solution in which HFP) was dissolved was prepared, and the negative electrode body was immersed in the polymer solution, so that the negative electrode body contained the polymer solution. Here, NMP corresponds to the solvent a, and NMP
A polymer solution in which 20% by weight of P (VdF / HFP) is dissolved corresponds to a polymer solution a ′. Next, the negative electrode body containing the polymer solution was pressed. The thickness of the negative electrode body excluding the polymer solution was 190 μm, and the porosity was 3 μm.
5%.

Next, the thickness of the polymer solution attached to the negative electrode main body was set to 45 μm, and the negative electrode main body was immersed in a mixed solvent of 25 wt% of water and 75 wt% of methanol to extract NMP. The thickness of the porous polymer electrolyte membrane formed on the negative electrode surface was 15 μm. Here, water 25 wt%
And a mixed solvent of methanol and 75 wt% corresponds to the solvent b.

Next, the electrode was dried at 100 ° C. for 30 minutes to remove water and the like adhering to the electrode, thereby obtaining a negative electrode provided with the porous polymer electrolyte according to the present invention. The total weight of the active material and the conductive additive filled per unit area was 14 mg / cm ² .

The positive electrode and the negative electrode were wound in a stacked state and inserted into a stainless steel case having a bottom surface with a radius of 6.7 mm and a height of 47.0 mm to assemble a cylindrical battery.
Thereafter, 2.5 g of a mixed (volume 1: 1) electrolyte solution of ethylene carbonate and diethyl carbonate containing 1 M LiPF ₆ was added, and finally, aging treatment was performed at 60 ° C. for 48 hours to obtain a nominal capacity of 520 mAh of the present invention. A battery (A) was prepared.

Example 2 A process for manufacturing a positive electrode will be described. Lithium nickelate 66.8wt%, acetylene black 1.4wt%, P (VDF / HFP) 2.8w
t% and 29 wt% of NMP are mixed to a width of 20%.
It was applied to both sides of an aluminum foil having a thickness of 480 mm, a length of 480 mm and a thickness of 20 μm, dried at 90 ° C. to evaporate NMP, thereby preparing a positive electrode body. Next, the positive electrode body was pressed. The thickness of the positive electrode body after pressing was 160 μm, the porosity was 30%, and the total weight of the active material and the conductive auxiliary filled per unit area was 21 mg / cm ² .

Next, a polymer solution was prepared by dissolving 12% by weight of P (VdF / HFP) in dimethylformamide (DMF), and the positive electrode body was immersed in this polymer solution, so that the positive electrode body contained the polymer solution. . Where DM
F corresponds to the solvent a, and 12 wt% of P (VdF
/ HFP) is a polymer solution b ′
Is equivalent to Next, after sandwiching the cathode body between the two glass tubes and removing the polymer solution attached to the electrode body surface, the cathode body was immersed in water to extract DMF. Here, water corresponds to the solvent b.

Next, the electrode was dried at 130 ° C. for 30 minutes to remove water and the like adhering to the electrode to obtain a positive electrode provided with the porous polymer electrolyte according to the present invention. A porous polymer electrolyte layer having a thickness of 5 μm was formed on the surface of the positive electrode even though the solvent extraction treatment was performed after removing the polymer solution attached to the surface of the positive electrode. Next, a manufacturing process of the negative electrode will be described. Graphite 81wt%, P (VdF / HF
P) A paste in which 9 wt% of NMP and 10 wt% of NMP were mixed was applied to both surfaces of a copper foil having a thickness of 14 μm, dried at 90 ° C. to evaporate NMP, and a negative electrode body was prepared. Next, the negative electrode body was pressed. The thickness of the negative electrode body after pressing is 190μ.
m, the porosity is 35%, and the total weight of the active material and the conductive auxiliary filled per unit area is 14 mg / cm.
^{Was 2} .

Next, 12 wt% of P (VdF /
A polymer solution in which HFP) was dissolved was prepared, and the negative electrode body was immersed in the polymer solution, so that the negative electrode body contained the polymer solution. Here, DMF corresponds to solvent a, and DMF
The polymer solution in which 12% by weight of P (VdF / HFP) is dissolved corresponds to the polymer solution b ′. Next, after sandwiching the negative electrode body between two glass tubes and removing the polymer solution adhering to the surface of the negative electrode body, the negative electrode body is immersed in water to form a DM.
F was extracted. Here, water corresponds to the solvent b.

Next, the negative electrode was dried at 100 ° C. for 30 minutes to remove water and the like adhering to the negative electrode surface, thereby obtaining a negative electrode provided with the porous polymer electrolyte according to the present invention. Although the solvent extraction treatment was performed after removing the polymer solution attached to the negative electrode surface, a 5 μm-thick porous polymer electrolyte layer was formed on the negative electrode surface.

The above positive electrode and negative electrode were wound together with a porous polymer electrolyte membrane (thickness: 23.7 μm, porosity: 41%) interposed therebetween, and the bottom surface had a radius of 6.7 mm and a height of 4 mm.
It was inserted into a 7.0 mm stainless case to assemble a cylindrical battery. Thereafter, 2.5 g of a mixed electrolyte (volume 1: 1) of ethylene carbonate and diethyl carbonate containing 1 M LiPF ₆ was injected thereinto, and finally, 4 g at 60 ° C.
Aging treatment for 8 hours, nominal capacity 520mA
h, a battery (B) according to the present invention was prepared.

[Comparative Example 1] As a comparative example, a battery using an electrode manufactured by pressing a polymer solution after subjecting the electrode body to a polymer solution, performing a solvent extraction process, and preparing the battery was prepared. First, the manufacturing process of the positive electrode will be described. Lithium nickelate 6
6.8 wt%, acetylene black 1.4 wt%, P
(VDF / HFP) A paste in which 2.8 wt% of NMP and 29 wt% of NMP were mixed was applied to both sides of an aluminum foil having a width of 20 mm, a length of 480 mm, and a thickness of 20 μm, and dried at 90 ° C. to evaporate the NMP. The main body was prepared.

Next, 20 wt% of P (VdF /
HFP) was dissolved in the polymer solution, and the positive electrode body was immersed in the polymer solution, so that the positive electrode body contained the polymer solution. Here, NMP corresponds to the solvent a, and a polymer solution obtained by dissolving 20 wt% of P (VdF / HFP) in NMP corresponds to the polymer solution a ′. Next, after sandwiching the positive electrode body between the two glass tubes and removing the polymer solution adhering to the surface of the positive electrode body, the positive electrode body is immersed in water and NM
P was extracted. Here, water corresponds to the solvent b.

Next, the positive electrode main body was dried at 130 ° C. for 30 minutes to remove water and the like adhering to the surface of the positive electrode main body. Despite performing the solvent extraction process after removing the polymer solution attached to the electrode surface, the thickness of the positive electrode surface was 5 μm.
Of the porous polymer electrolyte layer was formed.

Next, the positive electrode body provided with the porous polymer electrolyte was pressed. The thickness of the positive electrode body is 160 μm,
The porosity of the electrode excluding the porous polymer electrolyte was 30%. No porous polymer electrolyte layer was observed on the positive electrode surface after pressing, and the positive electrode surface was covered with a nonporous polymer electrolyte membrane having a thickness of 1 μm or less. The total weight of the active material and the conductive additive filled per unit area was 21 mg / cm ² .

Next, the manufacturing process of the negative electrode will be described.
Graphite 81wt%, P (VdF / HFP) 9wt
%, NMP 10wt% mixed paste with thickness 14μ
m, and dried at 90 ° C. to evaporate NMP to prepare a negative electrode body.

Next, 20 wt% of P (VdF /
A polymer solution in which HFP) was dissolved was prepared, and the negative electrode body was immersed in the polymer solution, so that the negative electrode body contained the polymer solution. Here, NMP corresponds to the solvent a, and a polymer solution obtained by dissolving 20 wt% of P (VdF / HFP) in NMP corresponds to the polymer solution a ′. Next, after sandwiching the negative electrode body between two glass tubes and removing the polymer solution adhering to the surface of the negative electrode body, the negative electrode body is immersed in water and NMP
Was extracted. Here, water corresponds to the solvent b.

Next, the negative electrode body was dried at 100 ° C. for 30 minutes to remove water and the like adhering to the negative electrode body. Although the solvent extraction treatment was performed after removing the polymer solution attached to the electrode surface, a 5 μm-thick porous polymer electrolyte layer was formed on the negative electrode surface.

Next, the negative electrode body provided with the porous polymer electrolyte was pressed. The thickness of the negative electrode body was 190 μm, and the porosity of the electrode excluding the porous polymer electrolyte was 35 μm.
%Met. No porous polymer electrolyte layer was observed on the negative electrode surface after pressing, and the negative electrode surface was covered with a nonporous polymer electrolyte membrane having a thickness of 1 μm or less. The total weight of the active material and the conductive assistant filled per unit area is 14 mg / cm.
^{Was 2} .

A porous polymer electrolyte membrane (having a thickness of 26.7 μm and a porosity of 44%) interposed between the positive electrode and the negative electrode was wound in a pile, and the bottom surface had a radius of 6.7 mm and a height of 6.7 mm. It was inserted into a 47.0 mm stainless steel case to assemble a cylindrical battery. Thereafter, 2.5 g of a mixed (volume 1: 1) electrolytic solution of ethylene carbonate and diethyl carbonate containing 1M LiPF ₆ was injected, and finally 60 ° C.
Aging treatment for 48 hours at nominal capacity of 520
A battery (C) of mAh was prepared.

[Discharge Performance] Next, the discharge performance of the battery will be described. Batteries (A) and (B) according to the present invention,
Comparative Example (C) was tested at room temperature with a current of 1 CA at 4.1 V.
After charging for 2 hours at a constant voltage of 4.1 V, the battery was discharged to 3.0 V at a current of 1 CA.

FIG. 1 shows the results of the discharge test. As a result,
It can be seen that the batteries (A) and (B) according to the present invention show better discharge performance than the comparative battery (C). In Example 1, after the thickness of the polymer solution attached to the positive electrode surface and the negative electrode surface was set to 45 μm, the electrode was immersed in an extraction solvent to perform solvent extraction, and the electrode surface was provided with a porous polymer electrolyte membrane. However, in addition to the above, a solvent extraction process is performed after removing the polymer solution attached to the electrode surface, and a porous polymer electrolyte or a separator such as polypropylene is interposed between the positive electrode and the negative electrode to form an electrode group. . Furthermore, although a mixture of alcohol and water was used as the solvent b, alcohol, water, and acetone may be used alone or as a mixture thereof. Also,
At least one of the positive electrode and the negative electrode may use the electrode manufacturing method of the first embodiment.

Further, in Example 2 described above, the solvent extraction treatment was performed after removing the polymer solution attached to the electrode surface. However, the solvent extraction treatment was performed after the polymer solution attached to the electrode surface was reduced to a predetermined thickness. The porous polymer electrolyte membrane formed on the electrode surface may be used as a separator. Although water was used as the solvent b, alcohol,
Acetone or a mixture thereof may be used. Further, at least one of the positive electrode and the negative electrode
It is sufficient that the electrode manufacturing method described above is used. The positive electrode
The negative electrode may be composed of a combination of the electrode manufacturing methods of Examples 1 and 2.

[0049]

According to the conventional manufacturing process of an electrode provided with a porous polymer electrolyte, first, a polymer solution is contained in an unpressed electrode, then a solvent extraction treatment is performed, and then a pressing is performed. In addition, the pores of the polymer electrolyte layer formed on the electrode surface were crushed to become non-porous, hindering the movement of lithium ions, and the charge / discharge characteristics of the battery were poor.

In the manufacturing process of the electrode provided with the porous polymer electrolyte according to the present invention, the electrode body is pressed with the polymer solution contained therein, and then the solvent is extracted. In addition, the porous polymer electrolyte membrane layer is not made nonporous, and the battery has excellent charge / discharge performance.

Further, after the electrode body is pressed, a solvent in which the polymer is dissolved is included to perform the solvent extraction treatment. Therefore, the porous polymer electrolyte layer formed on the electrode surface is not pressed to be nonporous. As a result, the charge and discharge characteristics of the battery become excellent.

Further, by subjecting the solvent in which the polymer adhering to the electrode surface is dissolved to a predetermined thickness and then performing a solvent extraction treatment, the porous polymer electrolyte membrane formed on the electrode surface can be used as a separator. Thus, the manufacturing process of the battery is reduced.

[0053]

[Brief description of the drawings]

FIG. 1 is a characteristic diagram showing discharge curves after 4.1 V charging of batteries (A) and (B) according to the present invention and Comparative Example (C).

Claims (3)

[Claims] 1. A first step of manufacturing an electrode provided with an active material, and a second step of including a polymer solution a ′ in which a polymer having a property of being wetted or swelled by an electrolytic solution is dissolved in a solvent a. A step of pressing the electrode containing the polymer solution a ′, and a fourth step of extracting the solvent a contained in the electrode with a solvent b compatible with the solvent a. A method for manufacturing an electrode, comprising: 2. A first step of manufacturing an electrode provided with an active material, a second step of pressing the electrode, and a polymer solution obtained by dissolving a polymer having a property of being wetted or swelled by an electrolytic solution in a solvent a. a method for producing an electrode, comprising: a third step of including a ′ in an electrode; and a fourth step of extracting the solvent a contained in the electrode with a solvent b compatible with the solvent a. . 3. A non-aqueous electrolyte secondary battery in which at least one of a positive electrode and a negative electrode uses an electrode manufactured by the method according to claim 1.