JP2002124299A - Manufacturing method for nonaqueous electrolyte secondary battery having polymer electrolyte - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method for a nonaqueous electrolyte secondary battery using a polymer electrolyte having high capacity and little dispersion. SOLUTION: An electrode sheet provided with a mix layer on both surfaces of a band-like collector is turned around an impregnating roll provided with holes in a cylinder part installed in a polymer impregnating tank storing a polymer solution prepared by dissolving a polymer in a solvent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a non-aqueous electrolyte secondary battery having a polymer electrolyte.

[0002]

2. Description of the Related Art A non-aqueous electrolyte secondary battery is widely used as a power source for small and portable electronic devices, taking advantage of its high energy density. In addition, application to electric vehicles is expected in the near future.

A nonaqueous electrolyte secondary battery uses a material capable of inserting and extracting lithium as a positive electrode active material and a negative electrode active material. Specifically, a transition metal composite oxide such as lithium cobalt oxide is used as the positive electrode active material, and a carbonaceous material such as graphite is used as the negative electrode active material. In the reaction of the nonaqueous electrolyte secondary battery, lithium released from the positive electrode active material is inserted into the negative electrode active material during charging, and lithium stored in the negative electrode active material is released into the positive electrode active material during discharging. .

As an electrolytic solution for a non-aqueous electrolyte secondary battery, LiPF is mixed with a mixed organic solvent containing various carbonates such as ethylene carbonate and ethyl methyl carbonate.
6. A non-aqueous electrolyte in which a lithium salt such as LiBF4 is dissolved is used.

The shape of the power generating element of the non-aqueous electrolyte secondary battery is as follows:
A sheet-like positive electrode plate in which a positive electrode mixture containing a positive electrode active material is applied to a current collector, and a sheet-like negative electrode plate in which a negative electrode mixture containing a negative electrode active material is applied to a current collector are made of a polyolefin-based material such as polyethylene or polypropylene. A winding type wound through a separator having fine pores, a folding type in which a sheet-like positive electrode plate and a sheet-like negative electrode plate are folded through a separator and laminated together, a plate-like positive plate and a plate-like negative plate, Are stacked on each other with a separator interposed therebetween.

In such a non-aqueous electrolyte secondary battery, since the non-aqueous electrolyte is used as described above, in order to prevent decomposition of the electrolyte due to overcharging or internal short circuit,
Various protection circuits were required.

In non-aqueous electrolyte secondary batteries, attempts have been made to use polymer electrolytes instead of non-aqueous electrolytes in order to reduce the amount of free electrolyte and improve battery safety. As the polymer electrolyte, an all-solid electrolyte composed of a polymer and an electrolyte salt and a gel electrolyte obtained by swelling the polymer with a non-aqueous electrolyte have been studied. A porous polymer electrolyte which swells with a non-aqueous electrolyte solution in the pores and is held to be promising.

An example of a conventional method for manufacturing a non-aqueous electrolyte secondary battery having a porous polymer electrolyte is as follows. First, an electrode sheet is manufactured in which a mixture layer containing an active material, a conductive auxiliary agent and a binder is applied to both surfaces of a current collector made of a strip-shaped metal foil and dried.

Next, a polymer impregnation tank storing a polymer solution in which a polymer is dissolved in a first solvent is prepared, and the electrode sheet is passed through the polymer solution in the polymer impregnation tank, so that the polymer solution is contained in the mixture layer. (Polymer impregnation step).

After that, the electrode sheet is immersed in a second solvent which is compatible with the first solvent and does not dissolve the polymer, and the first solvent in the polymer solution is extracted with the second solvent. , (Solvent extraction step), the first solvent is replaced with a second solvent. After that, the electrode sheet is dried to remove the second solvent. Then, micropores are formed after the second solvent in the polymer solution has escaped, and an electrode sheet having a porous polymer in the mixture layer is obtained.

Therefore, by immersing the electrode sheet in a non-aqueous electrolyte, the non-aqueous electrolyte is retained in the pores of the porous polymer, and at the same time the polymer is swollen with the non-aqueous electrolyte. An electrode sheet including the electrolyte in the mixture layer is obtained (electrolyte impregnation step). Then, the electrode sheet is cut into a required length and width, and wound together with the electrode sheet of the counter electrode and the separator, thereby forming a battery.

Alternatively, an electrode sheet provided with a porous polymer in a mixture layer is cut into a required length and width, wound together with an electrode sheet of a counter electrode and a separator to form a power generating element, and stored in a battery case. Thereafter, by pouring the non-aqueous electrolyte, a battery having the porous polymer electrolyte in the electrode mixture layer is obtained.

The conventional method of the above-mentioned polymer impregnation step will be described in more detail. First, an electrode sheet having a mixture layer on both surfaces of a belt-shaped current collector is rotated around an impregnation roll provided in a polymer impregnation tank storing a polymer solution in which a polymer is dissolved in a first solvent. The mixture layer of the electrode sheet was impregnated with the polymer solution. Further, by passing the electrode sheet through a pressure roll provided outside the polymer impregnation tank, excess polymer solution on the surface of the mixture layer is removed. Excess polymer solution was blown away by blowing air from an extending nozzle.

[0014]

A conventional polymer impregnation step will be described with reference to the drawings. FIG. 2 schematically shows an apparatus for impregnating a positive electrode sheet with a polymer. In addition,
The same applies to the case of the negative electrode sheet.

In FIG. 2, 10 is an electrode sheet, 11 is a polymer solution, 21 is a polymer impregnating tank, 22 is an impregnating roll, 23 is a guide roll, 24 is a pair of squeezing rolls,
5 is a first roll, 26 is an intermediate roll, 27 is a second roll, 28 is a nozzle, 29 is a cover, 30 is a shaft, and 31 is a handle.

In this polymer impregnating apparatus, the electrode sheet 10 is supplied from the right direction A in the drawing, travels to the left, and is sent to the next solvent extraction step from the left direction B in the drawing. The electrode sheet 10 is formed by applying a positive electrode mixture layer to a strip-shaped aluminum foil. The mixture layer is applied to both sides, and a non-application portion (not shown) in which the mixture is not applied at predetermined intervals. Are formed. The electrode sheet 10 is continuously supplied to the present apparatus and continuously processed. However, at the final stage, the electrode sheet 10 is cut at the non-applied portion, and a lead is welded to the non-applied portion to be wound together with the negative electrode and the separator. It is turned and accommodated in the case, and the electrolyte is injected (electrolyte impregnation step).

As shown in FIG. 2, a polymer solution 11 is stored in a polymer impregnating tank 21, in which an impregnating roll 22 is rotatably disposed, and the electrode sheet 10 guided by a guide roll 23 is impregnated with the polymer. The polymer solution 11 stored in the impregnation tank 21 is continuously supplied into the tank 21 while the electrode sheet 10 is turned upward around the impregnating rolls 22, into the mixture layer of the electrode sheet 10. Impregnated.

The electrode sheet 10 turned upward from the impregnating roll 22 passes between a pair of squeezing rolls 24 and sequentially travels on a first roll 25, an intermediate roll 26, and a second roll 27.

Above the impregnation tank 21, a pair of squeezing rolls 2
4 are arranged, and the polymer solution 10 excessively attached to the surface of the electrode sheet 10 is squeezed out.

Above the first roll 25, the electrode sheet 1
A nozzle 28 having a slit (not shown) extending in the width direction of 0 is provided, to which compressed air from a compressor not shown is supplied. The compressed air is not heated, but is cooled to room temperature if necessary. As a result, the air blown out from the slit of the nozzle 28 is sprayed in a film form on the mixture layer on the surface of the electrode sheet 10, and the excess polymer solution 10 remaining on the surface of the electrode sheet 10 is blown off.

Further, the nozzle 28 is rotatably held by a shaft 30 arranged in the axial direction with the first roll 25, and a handle 31 is provided. The direction in which the compressed air is blown out can be adjusted, and the angle and distance of the nozzle 28 with respect to the electrode sheet 1 can be changed.

Further, a cover 29 having an air inlet is provided around the nozzle 28 so that the polymer solution 10 blown off from the surface of the electrode sheet 10 is collected in the cover 29.

The nozzle 28 and the cover 29 are provided in a further upper part (the same parts are denoted by the same reference numerals in FIG. 2 and are shown in detail in FIG. 2).
The excess polymer solution 10 can be blown off on both sides of the substrate.

FIG. 3 is an enlarged view showing the relationship between the electrode sheet and the impregnation roll in the conventional polymer impregnation step. In FIG. 3, 1 is an electrode sheet, 2 is an impregnating roll,
Reference numeral 3 denotes a cylinder part of the impregnation roll, 4 denotes a mixture layer in contact with the cylinder part of the impregnation roll, 5 denotes a mixture layer not in contact with the cylinder part of the impregnation roll, 6 denotes a part where the mixture layer is not applied, and 7 and 8
Is the level of the polymer solution.

The electrode sheet 1 travels from the direction A to the direction B, enters the polymer solution from 7, goes around the impregnating roll 2, and emerges from 8. The electrode sheet 1 is in contact with the cylinder portion 3 of the impregnating roll between X and Y.

In the conventional polymer impregnation step, since the ordinary impregnation roll 2 has no holes in the cylinder portion, when the electrode sheet 1 provided with the mixture layer on both sides goes around the impregnation roll 2, The surface of the mixture layer 5 not in contact with the cylinder part is always in contact with the polymer solution for 7 to 8, but the mixture layer 4 in contact with the cylinder part is in the polymer solution between 7 and X and between Y and 8 But does not come into contact with the polymer solution between X and Y.

As a result, the amount of the polymer solution impregnated in the mixture layer 4 in contact with the cylinder portion 3 of the impregnation roll was smaller than the amount of the polymer solution impregnated in the mixture layer 5 not in contact with the cylinder portion. That is, there is a problem that the polymer solution impregnation amounts of the mixture layers on both surfaces are different. Normally, electrode sheet 1
Since the resin did not bend at an acute angle, the diameter of the cylinder portion 3 of the impregnation roll was large, and the amount of the polymer solution impregnated in the mixture layer on both surfaces was often significantly different.

Further, when the conventional polymer impregnation tank is used for a long time, there is a problem that the temperature of the polymer solution rises, the mixture layer becomes soft, and the mixture layer peels off from the electrode sheet and falls off. .

The present invention has been made in view of the above circumstances, and an object of the present invention is to eliminate the difference in the amount of the polymer solution impregnated into the mixture layers on both surfaces of the electrode sheet in the polymer impregnation step, and to further reduce the polymer impregnation step. An object of the present invention is to provide a method for manufacturing a non-aqueous electrolyte secondary battery having a high capacity and a small variation in the battery by preventing the mixture layer from peeling and falling off.

[0030]

To solve the above-mentioned problems, the invention of claim 1 provides a method for manufacturing a non-aqueous electrolyte secondary battery in which at least one of a positive electrode and a negative electrode holds a polymer electrolyte. Then, an impregnation roll is provided in a polymer impregnation tank storing a polymer solution in which a polymer is dissolved in a solvent, and an electrode sheet provided with a mixture layer on both surfaces of a belt-shaped current collector orbits around the impregnation roll. The method further includes a step of impregnating the mixture layer of the electrode sheet with a polymer solution, wherein a surface of the mixture layer in contact with a cylinder portion of the impregnation roll is in contact with the polymer solution.

According to the first aspect of the present invention, in the polymer impregnation step, the difference in the amount of the polymer solution impregnated between the mixture layers on both surfaces of the electrode sheet can be eliminated, and the nonaqueous electrolyte having a high capacity and small variation in the battery A method for manufacturing a secondary battery can be provided.

Further, the invention of claim 2 is characterized in that, in the invention of claim 1 described above, a hole is provided in a cylinder portion of the impregnating roll.

According to the second aspect of the present invention, the surface of the mixture layer in contact with the cylinder portion of the impregnation roll can be brought into sufficient contact with the polymer solution.

Further, the invention of claim 3 provides the above-mentioned claim 1.
The present invention is characterized in that irregularities are provided on the surface of the cylinder portion of the impregnation roll.

According to the third aspect of the present invention, the surface of the mixture layer in contact with the cylinder portion of the impregnation roll can be brought into sufficient contact with the polymer solution.

According to a fourth aspect of the present invention, in the method for manufacturing a nonaqueous electrolyte secondary battery, the temperature of the polymer solution in the polymer impregnation tank can be adjusted.

According to the fourth aspect of the present invention, the temperature rise of the polymer solution in the polymer impregnation tank is prevented, and the temperature of the polymer solution is kept at an optimum value, thereby preventing the mixture layer from peeling or falling off from the electrode sheet. Thus, a method for manufacturing a high-capacity non-aqueous electrolyte secondary battery can be provided.

According to a fifth aspect of the present invention, in the method for manufacturing a nonaqueous electrolyte secondary battery, the polymer impregnation tank can be moved up and down.

According to the fifth aspect of the present invention, when the polymer impregnation step is stopped, it becomes easy to clean the polymer impregnation tank and the impregnation roll.

[0040]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described with reference to the drawings based on an example applied to the manufacture of a lithium ion secondary battery. This lithium ion secondary battery includes a power generating element formed by winding a band-shaped positive electrode and a band-shaped negative electrode with, for example, a separator made of a polyolefin-based porous film interposed therebetween, and the negative electrode is, for example, a copper foil. On both surfaces, a mixture layer containing graphite or the like as an active material is applied, and for the positive electrode, for example, a mixture layer containing LiCoO ₂ or the like as an active material is applied on both surfaces of an aluminum foil. It is provided with a porous polymer electrolyte.

The outline of the apparatus used in the step of impregnating the electrode sheet with the polymer according to the present invention is substantially the same as that shown in FIG. However, the temperature of the polymer solution 11 in the polymer impregnation tank 21 in FIG. 2 can be adjusted, and the polymer impregnation tank 21 can be moved up and down.

FIG. 1 shows an example of a detailed vertical cross section of the polymer impregnation tank of the present invention. In FIG. 1, symbols 10, 11, 2
1 and 22 are the same as those in FIG. 2; 12 is a cylinder portion of the impregnating roll 22, 13 is a current collector, 14 is a mixture layer that contacts the cylinder portion 12, and 15 is a mixture layer that does not contact the cylinder portion 12. , 16 are holes provided in the cylinder portion 12, and 17 is a polymer solution in the cylinder portion 12.

As shown in FIG. 1, an electrode sheet 10 having a mixture layer on both sides runs from the direction A to the direction B. At this time, the polymer solution 11 stored in the polymer impregnation tank 21 is impregnated in the mixture layer of the electrode sheet 10 while the electrode sheet 10 is traveling in the polymer solution 11.
In this case, the polymer solution 11 is always supplied from the direction of the black arrow to the mixture layer 15 not in contact with the cylinder portion 12, and the polymer solution The solution 17 is supplied from the hole 16 provided in the cylinder portion 12 in the direction of the white arrow, and as a result, the mixture layer 14 in contact with the cylinder portion 12 and the mixture layer 1 not in contact with the cylinder portion 12
In No. 5, there is no difference in the amount of the polymer solution impregnated.

The hole 1 provided in the cylinder 12
The size, shape, and number of 6 can be appropriately selected so that the polymer solution is easily supplied from the direction of the white arrow.
In some cases, the cylinder 12 itself may be a porous body.

FIG. 4 shows another example of the detailed vertical cross section of the polymer impregnation tank of the present invention. In FIG. 4, symbols 10 to 22 indicate the same as those in FIG.

In this case, the polymer solution 11 is always supplied to the mixture layer 15 not in contact with the cylinder portion 12 in the direction indicated by the black arrow, and the cylinder portion 12 has irregularities on its surface. Contacting mixture layer 14
The polymer solution 1 between the irregularities on the cylinder surface
1 is supplied, and as a result, the mixture layer 14 that contacts the cylinder portion 12 and the mixture layer 15 that does not contact the cylinder portion 12
This eliminates the difference in the amount of polymer solution impregnated.

The size, shape and number of the irregularities 23 provided on the surface of the cylinder portion 12 can be appropriately selected so that the polymer solution can be easily supplied.

In the above description, the case where the polymer solution is impregnated in the mixture layer of the positive electrode has been described. However, the present invention is also applicable to the case where the polymer solution is impregnated in the mixture layer of the negative electrode.

When the electrode sheet is passed through the polymer impregnation tank for a long time, the temperature of the polymer solution in the polymer impregnation tank rises, and the mixture layer of the electrode sheet is easily peeled off. To prevent this, it is necessary to lower the temperature of the polymer solution. In addition, when starting the impregnation, depending on the season, the temperature of the polymer solution in the polymer impregnation tank may be low, the viscosity of the polymer solution may be high, and impregnation may be difficult. Need to be raised.

In order to solve these problems and to keep the temperature of the polymer solution in the polymer impregnation tank always at the optimum value, the present invention makes it possible to control the temperature of the polymer solution in the polymer impregnation tank. As a means, the entire polymer impregnation tank is placed in a constant temperature chamber, a temperature control device is attached to the outside of the polymer impregnation tank, or the polymer solution is once guided to the outside of the polymer impregnation tank, and the temperature control device is controlled. After the temperature has been adjusted through the process, a means such as returning to the polymer impregnation tank can be used.

Further, when the polymer impregnation step is completed, it is necessary to wash the polymer impregnation tank and the impregnation roll. However, if the polymer impregnation tank can be raised and lowered as in the present invention, the polymer impregnation tank is lowered during cleaning. As a result, the polymer impregnating tank and the impregnating roll can be washed separately, which facilitates the washing operation. If the polymer impregnation tank can be moved up and down, maintenance and inspection of the device is also convenient.

After the completion of the polymer impregnation step, the mixture layer of the electrode sheet can be provided with a porous polymer by passing through the solvent extraction step and the drying step. Thereby, a polymer having no pores in the mixture layer of the electrode sheet can be provided.

The polymer used in the present invention is preferably a copolymer of vinylidene fluoride (VdF) and hexafluoropropylene (HFP), but is not limited thereto.
For example, other polymers such as polyacrylonitrile (PAN) and polymethyl methacrylate (PMMA), or a mixture or copolymer thereof may be used. The weight average molecular weight of these polymers is 100,000 to 10
100,000 is preferred. When the molecular weight is 1,000,000 or more, the viscosity of the electrolytic solution becomes high when dissolved in a solvent, and it is difficult to impregnate the electrode. Therefore, neither is preferable.

As the organic solvent for dissolving or dispersing the above polymer, N-methyl-2-pyrrolidone, dimethylformamide, methyl ethyl ketone, methyl isobutyl ketone, toluene, xylene, tetrahydrofuran, acetone, acetonitrile, dimethyl carbonate, ethyl acetate, butyl acetate Etc. can be used.

As the positive electrode active material, it is preferable to use an oxide or the like capable of inserting and extracting lithium ions, and as the inorganic compound, a composition formula of Li _x MO 2 or Li _y M 2 O
4 (where M is a transition metal, 0 ≦ x ≦ 1, 0 ≦ y ≦ 2)
Embedded image, an oxide having tunnel-like vacancies, and a metal chalcogenide having a layered structure. Specific examples thereof include LiCoO2, LiNiO
2, LiMn2O4, Li2Mn2O4, MnO2, FeO
OH, FeO2, V2O5, V6O13, TiO2, TiS
₂ , nickel oxyhydroxide and the like. Examples of the organic compound include a conductive organic polymer such as polyaniline. Furthermore, regardless of an inorganic compound or an organic compound, the above-mentioned various active materials may be mixed and used.

As the negative electrode active material, a carbon-based material,
A lithium metal, a lithium alloy, an oxide material, or the like is used. As the carbon-based material, for example, artificial or natural graphite, pyrolytic carbons, cokes, glassy carbons, fired bodies of organic polymer compounds, mesocarbon microbeads, activated carbon, graphite, carbon fibers, and the like are used. As the oxide, a compound mainly composed of tin oxide is used. These are used in a powder state.

In the battery of the present invention, the solvent of the non-aqueous electrolyte is ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (D
MC), diethyl carbonate (DEC), γ-butyrol ctone, sulfolane, dimethyl sulfoxide, acetonitrile, dimethylformamide, dimethylacetamide, 1,2-dimethoxyethane, 1,2-diethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, A polar solvent such as dioxolan, methyl acetate, or a mixture thereof may be used.

The salts contained in the non-aqueous electrolyte include LiPF6, LiBF4, LiAsF6, LiClO
4, LiSCN, LiI, LiCF3SO3, LiCl,
A lithium salt such as LiBr and LiCF3CO2, or a mixture thereof may be used.

In the battery of the present invention, the separator is
Conventional polyolefin separators such as polyethylene and polypropylene having micropores can be used, or these separators may be used in combination with a solid polymer electrolyte. In some cases, only a polymer solid electrolyte containing an organic electrolyte may be used without using a polyolefin-based separator. As the polymer solid electrolyte containing the organic electrolyte, a gel polymer solid electrolyte, a porous polymer solid electrolyte, or the like can be used.

As the shape of the battery, batteries having any shape such as a square type, a cylindrical type, and a long cylindrical type can be used.

[0061]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below using preferred embodiments.

The positive electrode sheet was prepared by mixing 80 wt% of lithium cobalt oxide (LiCoO ₂ ) as an active material, 8 wt% of acetylene black as a conductive aid, and 12 wt% of polyvinylidene fluoride (PVdF) as a binder.
-Methylpyrrolidone (NMP) was added to prepare a paste, which was 42 mm wide, 480 mm long and 20 μm thick
m of an aluminum foil current collector was applied to both sides, dried at 100 ° C., and NMP was evaporated to produce the same. The obtained positive electrode sheet has a thickness of 180 μm and has a mixture layer on both surfaces of the current collector.

The positive electrode sheet was passed through the polymer impregnation tank shown in FIG. 1 to impregnate the mixture layer with the polymer solution. Here, a polymer solution (polymer concentration of 5 wt%) in which a polymer (copolymer of vinylidene fluoride and hexafluoropropylene) was dissolved in NMP (N-methyl-2-pyrrolidone) as a solvent was used.

In this impregnation step, the conventional positive electrode sheet using the impregnation roll having no holes in the cylinder portion was designated as a, and the positive electrode sheet using the impregnation roll having holes in the cylinder portion of the present invention was designated as A.

The negative electrode sheet was prepared by mixing 92% by weight of graphite (graphite) as an active material and 8% by weight of polyvinylidene fluoride as a binder, and mixing N-methylpyrrolidone (N
MP) to prepare a paste, which is then
m, a length of 480 mm and a thickness of 15 μm were applied to both sides of a copper foil, dried at 100 ° C., and evaporated to produce NMP.
The obtained negative electrode sheet had a thickness of 170 μm and provided a mixture layer on both surfaces of the current collector.

On the negative electrode sheet, the mixture layer was impregnated with the polymer solution under the same conditions as the positive electrode sheet. In this impregnation step, the negative electrode sheet using a conventional impregnation roll having no holes in the cylinder portion was designated as b, and the negative electrode sheet using the impregnation roll having holes in the cylinder portion of the present invention was designated as B.

In the next solvent extraction step, when the positive electrode sheet and the negative electrode sheet impregnated with the polymer solution in the mixture layer are passed through water, NMP in the polymer solution is extracted,
Water instead penetrates into the micropores of the polymer.

In the next drying step, the positive electrode sheet and the negative electrode sheet are passed through a drying oven at 120 ° C. for about 10 minutes, whereby water in the fine pores of the polymer is removed, and Thus, an electrode sheet containing a porous polymer was obtained.

Lead terminals were welded to the ends of the obtained positive electrode plate and negative electrode plate, respectively. 10 thickness for positive lead terminal
A 0 μm aluminum piece was used, and a 100 μm thick nickel piece was used for the negative electrode lead terminal. As the separator, a microporous polyethylene membrane having a width of 46 mm and a thickness of 25 μm was used.

Then, the positive electrode lead terminal and the negative electrode lead terminal are both formed as a winding start portion, and the positive electrode plate, the separator, the negative electrode plate and the separator are alternately overlapped in this order, and a polyethylene rectangular core is provided. Is wound around the power generation element in an elliptical spiral shape so that the long side is parallel to the winding center axis of the power generation element, to obtain a wound power generation element having a size of 46 × 35 × 4 mm.

This wound type power generating element is 47.0 m in height.
m, a width of 22.2 mm and a thickness of 6.4 mm were inserted into a stainless steel case to assemble a prismatic battery. And ethylene carbonate (EC) and diethyl carbonate (D
EC) at a volume ratio of 1: 1 and 1 mol / l of L
The electrolyte to which iPF6 was added was injected in vacuum.

After a certain period of time, the battery lid and the case were sealed and welded to produce a battery having a nominal capacity of 400 mAh. In addition, the battery combining the positive electrode sheet A and the negative electrode sheet b in Example 1, the battery combining the positive electrode sheet a and the negative electrode sheet B in Example 2, and the battery combining the positive electrode sheet A and the negative electrode sheet B in Example 3, A battery in which the positive electrode sheet a and the negative electrode sheet b were combined was designated as Comparative Example 1.

Each of these batteries was prepared at a temperature of 25 ° C.
At a constant current / constant voltage of 400 mA / 4.1 V
The battery was charged for 400 hours and discharged to 2.75 V at 400 mA. Here, the discharge capacity of each battery was compared. Table 1 summarizes the results.

[0074]

[Table 1]

From the results in Table 1, it was found that the battery of Comparative Example 1 using the electrode sheet manufactured using the conventional impregnated roll had a small discharge capacity and a large variation, whereas the battery of the present invention had a large variation. It was shown that the batteries of Examples 1 to 3 using the electrode sheets manufactured by using No. 1 had a large discharge capacity, a small variation, and a high capacity battery.

Next, using the battery of Example 3, the influence of the temperature of the polymer solution in the impregnation step was examined. Here, 20 batteries were each manufactured using the electrode sheet manufactured by changing the temperature of the polymer solution, the capacity was confirmed under the above conditions, and the discharge capacity of each battery was compared. Table 2 summarizes the results.

[0077]

[Table 2]

From the results shown in Table 2, the optimum temperature of the polymer solution in the impregnation step is in the range of about 0 to 60 ° C., and the discharge capacity is small even if the temperature is higher or lower than this range. Indicated.

[0079]

According to the present invention, there is provided a method for producing a non-aqueous electrolyte secondary battery in which a polymer is retained on at least one of a positive electrode and a negative electrode, wherein a polymer solution having a polymer dissolved in a solvent is stored. Impregnated rolls are provided in the polymer impregnated tank, and the electrode sheet provided with the mixture layer on both sides of the belt-shaped current collector is circulated around the impregnation rolls, thereby impregnating the mixture layer of the electrode sheet with the polymer solution. Wherein the mixture layer surface in contact with the cylinder portion of the impregnation roll is in contact with the polymer solution. The difference in the amount of the polymer solution impregnated in the layers can be eliminated, and a method for producing a nonaqueous electrolyte secondary battery having a high capacity and small variation in the battery can be provided.

The present invention also relates to the above-mentioned production method,
It is characterized in that the temperature of the polymer solution in the polymer impregnation tank can be adjusted, thereby preventing the temperature of the polymer solution in the polymer impregnation tank from rising and maintaining the temperature of the polymer solution at an optimum value. Separation of the mixture layer from the sheet can be prevented.

Further, the present invention is characterized in that, in the above-mentioned production method, the polymer impregnation tank can be raised and lowered, so that when the polymer impregnation step is stopped, the polymer impregnation tank and the impregnation roll can be easily washed. Becomes

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a detailed vertical cross section of a polymer impregnation tank of the present invention.

FIG. 2 is a diagram showing a conventional polymer impregnation step.

FIG. 3 is an enlarged view showing a relationship between an electrode sheet and an impregnation roll in a conventional polymer impregnation step.

FIG. 4 is a view showing another example of a detailed vertical cross section of the polymer impregnation tank of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 electrode sheet 2 impregnating roll 3 cylinder section of impregnating roll 4 mixture layer in contact with cylinder section of impregnating roll 5 mixture layer not in contact with cylinder section of impregnation roll DESCRIPTION OF SYMBOLS 10 Electrode sheet for positive electrodes 11 Polymer solution 12 Cylinder part of impregnation roll 22 13 Positive electrode current collector 14 Mixture layer which contacts cylinder part 12 15 Mixture layer which does not contact cylinder part 12 16 Hole provided in cylinder part 17 Polymer solution inside cylinder part 21 Polymer impregnation tank 22 Impregnation roll 23 Guide roll 24 A pair of squeezing rolls 25 First roll 26 Intermediate roll 27 Second roll 28 Nozzle 29 Cover 30 Shaft 31 Handle

Continuation of the front page (72) Inventor Yoshihiro Kuwahara No. 1 Nishinosho Inonoba-cho, Kichijoin, Minami-ku, Kyoto, Kyoto Prefecture Inside Nippon Battery Co., Ltd. No. 5 Inside S-Melcotech Co., Ltd. (72) Inventor Kazunori Tagawa No. 5 inside Kichijoin Nitta Ichidantancho, Minami-ku, Kyoto-shi Inside S-Melcotech Co., Ltd. (72) Inventor Naoto Matsueda Kyoto Minami 5F 0-29 AJ14 AK03 AL06 AL12 AM03 AM04 AM05 AM07 AM16 CJ22 CJ23 CJ30 DJ09 EJ12 HJ12 HJ14 5H050 AA19 BA17 CA08 CB07 CB12 GA22 GA23 GA29 HA12 HA14

Claims (5)

[Claims] 1. A method for producing a non-aqueous electrolyte secondary battery in which a polymer electrolyte is held on at least one of a positive electrode and a negative electrode, the method comprising: impregnating a polymer in which a polymer solution obtained by dissolving a polymer in a solvent is stored. A step of impregnating the polymer solution into the mixture layer of the electrode sheet by providing an impregnating roll in the tank and rotating an electrode sheet having a mixture layer on both sides of the belt-shaped current collector around the impregnation roll; Wherein the surface of the mixture layer in contact with the cylinder portion of the impregnating roll is in contact with the polymer solution. 2. The method for producing a non-aqueous electrolyte secondary battery according to claim 1, wherein holes are provided in a cylinder portion of the impregnation roll. 3. The method for producing a non-aqueous electrolyte secondary battery according to claim 1, wherein irregularities are provided on the surface of the cylinder portion of the impregnation roll. 4. The method for producing a nonaqueous electrolyte secondary battery according to claim 1, wherein the temperature of the polymer solution in the polymer impregnation tank can be adjusted. 5. The method for producing a non-aqueous electrolyte secondary battery according to claim 1, wherein the polymer impregnation tank is movable up and down.