JP2003036885A - Manufacturing method of nonaqueous electrolyte battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a nonaqueous electrolyte battery, which can improve the load characteristics of the battery. SOLUTION: The manufacturing method of the nonaqueous electrolyte battery comprises the following processes of; housing electrode groups 9 in a film container for impregnation 8, the electrode groups 9 consisting of laminated materials containing positive and negative electrodes and wound or bent into flat shapes, injecting a nonaqueous electrolyte solution into the container for impregnation 8, depressurizing the container for impregnation 8, sealing up the container for impregnation 8, applying pressure from the outside to the container for impregnation 8, and sealing up the electrode groups 9 taken out of the container for impregnation 8 in a film outer sheath or a flat outer sheath.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for manufacturing a non-aqueous electrolyte battery.

[0002]

2. Description of the Related Art With the recent development of electronic devices,
There is a demand for the development of a non-aqueous electrolyte secondary battery that is lightweight, has a high energy density, and can be repeatedly charged and discharged. Lithium secondary batteries and lithium ion secondary batteries are known as such secondary batteries. Examples of the structure of the electrode group of the secondary battery include a wound structure, a laminated structure, and a pellet structure. In general, the larger the reaction area between the positive electrode and the negative electrode, the better the load characteristics. When used in electronic devices that consume a large amount of current per hour, a wound structure may be used to improve the load characteristics. desirable. Further, in long-term use such as memory backup, since the load characteristics are not so required, the positive electrode and the negative electrode in pellet form can be used.

However, recently, even for small electronic devices, a battery having a high load characteristic for communication and display has been demanded. In order to improve the load characteristics, it is necessary to increase the reaction area between the positive electrode and the negative electrode.

In order to increase the reaction area, it is desirable to use a wound electrode group. Japanese Patent Laid-Open No. 11-3456
No. 26 and Japanese Patent Laid-Open No. 2000-164259 disclose an electrode group for a flat battery in which a positive electrode case and a negative electrode case made of metal are caulked and sealed via a resin gasket that provides electrical insulation between them. The use of a wound electrode group is disclosed.

According to the flat type batteries described in these publications, a large reaction area can be obtained even if the battery is small. Further, paragraphs [0017] to [0018] of Japanese Patent Laid-Open No. 2000-164259 disclose a method for manufacturing a flat battery. First, a positive electrode plate and a negative electrode plate are wound around a separator and pressure-molded into an electrode plate group having an oval cross section. Dip the electrode group into the electrolyte in a closed container and
The electrode plate group is impregnated with the electrolytic solution by repeating the operation of reducing the pressure to 0 mmHg, holding it for 10 seconds, and returning it to atmospheric pressure three times. Next, this electrode plate group is put into a positive electrode case, covered with a negative electrode case having a gasket fitted in a sealing portion, inserted into a sealing die, and caulked and sealed with a hydraulic press to obtain a flat battery.

However, Japanese Patent Laid-Open No. 2000-16425
According to the manufacturing method described in Japanese Patent Laid-Open No. 9, it is difficult to obtain high load characteristics.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for manufacturing a non-aqueous electrolyte battery which can improve load characteristics.

[0008]

Means for Solving the Problems A method for manufacturing a non-aqueous electrolyte battery according to the present invention is for impregnating a film with an electrode group having a shape in which a laminate including a positive electrode and a negative electrode is wound or bent into a flat shape. A step of storing in a container, a step of injecting a non-aqueous electrolytic solution into the impregnation container, a step of depressurizing the impregnation container, a step of sealing the impregnation container, and the impregnation container The method is characterized by comprising a step of applying pressure from the outside and a step of sealing the electrode group taken out from the impregnation container in a film outer casing or a flat outer casing.

In the method for producing a non-aqueous electrolyte battery according to the present invention, a step of accommodating an electrode group having a shape in which a laminate including a positive electrode and a negative electrode is rolled or bent into a flat shape in a film-made impregnation container. And a step of injecting a gel electrolyte precursor into the impregnation container, a step of sealing the impregnation container, and gelling the gel electrolyte precursor while fixing the thickness of the impregnation container to a constant dimension. And a step of sealing the electrode group taken out from the impregnation container in a film outer casing or a flat outer casing.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION An example of a method for manufacturing a first non-aqueous electrolyte battery according to the present invention will be described.

This first non-aqueous electrolyte battery manufacturing method is as follows:
A step of accommodating an electrode group having a shape in which a laminate including a positive electrode and a negative electrode is wound or bent in a flat shape in a film-made impregnation container, and a step of injecting a non-aqueous electrolyte into the impregnation container A step of depressurizing the inside of the impregnating container, a step of sealing the impregnating container, a step of applying pressure to the impregnating container from the outside, and a step of forming the electrode group taken out from the impregnating container from a film And a step of sealing the inside of the outer casing or the flat outer casing.

According to such a manufacturing method, after injecting the non-aqueous electrolyte, the pressure in the impregnating container is reduced, and the container is hermetically sealed under reduced pressure, and then pressure is applied to the container from the outside.
The electrode group can be uniformly and quickly impregnated with the nonaqueous electrolytic solution. As a result, the load characteristics of the non-aqueous electrolyte battery can be improved. In addition, since the electrolytic solution is impregnated in a container different from the outer casing of the battery, it is possible to prevent the sealed portion of the outer casing from being contaminated with the electrolytic solution and adhere to the sealed portion of the outer casing. It is possible to avoid corrosion of the electric circuit and the like of the electronic device by the electrolytic solution. Further, since the step of cleaning the sealed portion of the outer package is not necessary, the manufacturing method can be simplified.

An example of the method for manufacturing the second non-aqueous electrolyte battery according to the present invention will be described.

The second method for manufacturing a non-aqueous electrolyte battery is as follows:
A step of accommodating an electrode group having a shape in which a laminate including a positive electrode and a negative electrode is wound or bent in a flat shape in a container for impregnation made of film, and a step of injecting a gel electrolyte precursor into the container for impregnation A step of sealing the container for impregnation, a step of gelling the gel electrolyte precursor while fixing the thickness of the container for impregnation to a constant dimension, and the electrode group taken out from the container for impregnation. And a step of sealing in a film outer casing or a flat outer casing.

Here, the thickness of the impregnation container means the thickness of the entire impregnation container, not the thickness of the wall of the impregnation container.

According to such a manufacturing method, the distance between the positive electrode and the negative electrode can be kept constant even when the film outer package is used, so that the internal resistance of the battery is lowered and the load characteristics are improved. In addition, it is possible to prevent the battery from being deformed due to the variation in the battery thickness as the charge / discharge cycle progresses. Further, since the electrolytic solution is impregnated in a container different from the outer casing of the battery, it is possible to prevent the sealed portion of the outer casing from being contaminated with the electrolytic solution.

In this manufacturing method, when using the film outer casing, it is preferable to carry out initial charging while keeping the battery thickness constant. Thereby, the load characteristics of the battery can be further improved.

The positive electrode, the negative electrode, the separator, the outer casing and the impregnating container used in the first and second manufacturing methods will be described below.

1) Positive Electrode This positive electrode is formed of a current collector carrying a positive electrode layer containing an active material and a conductive material.

Examples of the active material include various oxides (for example, lithium manganese composite oxide such as LiMn ₂ O ₄ and manganese dioxide, lithium nickel composite oxide such as LiNiO ₂ and lithium cobalt such as LiCoO _2). Examples thereof include composite oxides, lithium cobalt nickel composite oxides, amorphous vanadium pentoxide containing lithium), chalcogen compounds (eg, titanium disulfide, molybdenum disulfide, etc.) and the like. Above all, it is preferable to use a lithium manganese composite oxide, a lithium cobalt composite oxide, or a lithium nickel composite oxide.

As the current collector, for example, aluminum expanded metal, aluminum foil, aluminum mesh, aluminum punched metal or the like can be used.

Examples of the conductive material (conductive filler) include carbon black (eg, acetylene black, furnace black, Ketjen black, etc.), graphites (eg, artificial graphite, powdered graphite, powdered expanded graphite, etc.). ), Crushed glassy carbon, powdered or crushed cokes, crushed carbon fiber, crushed graphitized carbon fiber, nickel powder and the like. The conductive materials may be used alone or in combination of two or more.

The positive electrode is prepared by, for example, kneading a positive electrode active material, a conductive material and a binder in the presence of a solvent to prepare a slurry, coating the slurry on a current collector, drying the slurry, and then pressing the slurry. It is produced by molding.

Examples of the binder include polyvinylidene fluoride, styrene-butadiene copolymer, carboxymethyl cellulose and derivatives thereof.

2) Negative Electrode This negative electrode is formed of a negative electrode layer containing an active material supported on a current collector.

Examples of the active material include a carbonaceous material that absorbs and releases lithium ions. Examples of such carbonaceous materials include those obtained by firing an organic polymer compound (for example, phenol resin, polyacrylonitrile, cellulose, etc.), those obtained by firing coke and mesophase pitch, and artificial graphite. , Carbonaceous materials represented by natural graphite and the like. Above all, it is preferable to use a carbonaceous material obtained by firing the mesophase pitch at a temperature of 500 to 3000 ° C. under atmospheric pressure or reduced pressure in an atmosphere of an inert gas such as argon gas or nitrogen gas.

As the current collector, for example, copper expanded metal, copper foil, copper mesh, copper punched metal or the like can be used.

The negative electrode may contain a conductive material (conductive filler). As the conductive material (conductive filler), the same materials as those described for the positive electrode can be used.

For the negative electrode, for example, a slurry is prepared by kneading a negative electrode active material and a binder in the presence of a solvent, and the slurry is applied to a current collector, dried, and then press-molded. It is produced by.

As the above-mentioned binder, the same binder as described above for the positive electrode can be mentioned.

3) Separator The separator may be of any type as long as it is capable of moving lithium ions while separating the positive electrode and the negative electrode. As the separator, for example, a microporous film or a non-woven fabric containing polyolefin (for example, polyethylene or polypropylene) as a main component can be used.

4) Exterior Body As the film used for the exterior body, for example, a laminated film in which a metal layer is interposed between a thermoplastic resin layer and a resin layer can be cited.

The thermoplastic resin layer serves as a heat-sealing surface of the outer package. Examples of the heat-fusible resin include modified polyethylene phthalate, acid modified polyethylene, acid modified polypropylene, ionomer, ethylene vinyl acetate (EVA) and the like. The thermoplastic resin layer may have a single layer or a multi-layer structure composed of a plurality of thermoplastic resins.

The metal layer plays a role of preventing invasion of moisture. The metal layer can be formed of, for example, aluminum, nickel, or stainless.

The resin layer plays a role of protecting the metal layer. The resin layer can be formed of, for example, a polyolefin such as nylon, polyethylene terephthalate (PET), or polypropylene. The resin layer may have a single layer or a multi-layer structure composed of a plurality of resins.

The flat type outer casing can be formed of a metal such as stainless steel.

5) Impregnation Container Examples of the film forming the impregnation container include a laminate film in which a metal layer is interposed between a thermoplastic resin layer and a resin layer. The thermoplastic resin layer, the resin layer, and the metal layer may be the same as those described in the section of (5) Outer package described above.

The non-aqueous electrolyte used in the above-mentioned first manufacturing method will be described.

The non-aqueous electrolytic solution is prepared, for example, by dissolving an electrolyte in a non-aqueous solvent.

Examples of the non-aqueous solvent include ethylene carbonate (EC) and propylene carbonate (P
C), butylene carbonate (BC), dimethyl carbonate (DMC), diethyl carbonate (DEC),
Ethyl methyl carbonate (EMC), γ-butyrolactone (γ-BL), sulfolane, acetonitrile, 1,
2-dimethoxyethane, 1,3-dimethoxypropane,
Dimethyl ether, tetrahydrofuran (THF), 2
-Methyltetrahydrofuran etc. can be mentioned.
The non-aqueous solvent may be used alone or in combination of two or more.

Examples of the electrolyte include lithium perchlorate (LiClO ₄ ), lithium hexafluorophosphate (L
iPF _6), lithium borofluoride (LiBF _4), lithium hexafluoroarsenate (LiAsF _6), lithium salts such as lithium trifluoromethane sulfonate (LiCF ₃ SO ₃₎ may be mentioned. The electrolytes may be used alone or in combination of two or more.

The amount of the electrolyte dissolved in the non-aqueous solvent is preferably in the range of 0.2 mol / L to 2 mol / L.

The gel electrolyte precursor used in the above-mentioned second manufacturing method will be described.

The gel electrolyte precursor contains a non-aqueous electrolyte and a gelling agent.

As the non-aqueous electrolyte, the same ones as mentioned above can be mentioned.

Examples of the gelling agent include organic or inorganic substances that form a crosslinked structure by covalent bonds, linear or branched polymers or copolymers having a repeating structure, and the like. Examples of such organic or inorganic substances include those having two or more reactive functional groups, bifunctional acrylates, trifunctional acrylates, tetrafunctional acrylates, reactive functional groups existing in a polymer, and intramolecular or intermolecular. Epoxy resin prepolymerized as a material to react, reactive functional groups exist in the polymer,
Examples thereof include a material in which a reactive functional group reacts with a low molecular weight material to form a crosslinked structure. On the other hand, such a polymer or copolymer exhibits a thickening effect by the entanglement of polymer chains, and specific examples thereof include polyethylene oxide or a derivative thereof, polyacrylonitrile or a derivative thereof, and the like. . Since the thickening action of the electrolyte is expressed by the entanglement of the materials, the thicker the molecular weight and the more the branched structure, the higher the thickening effect.

The gelling agent is preferably dissolved in the electrolytic solution. The type of gelling agent used in the gel electrolyte precursor may be one type or two or more types.

Gelation can be carried out, for example, by heating, irradiation with light or the like.

FIG. 1 shows an example of the non-aqueous electrolyte battery manufactured by the first method and the second method according to the present invention. Figure 1
FIG. 3 is a cross-sectional view showing an example of a non-aqueous electrolyte secondary battery manufactured by the method according to the present invention (for example, a coin type non-aqueous electrolyte secondary battery).

An electrode group 4 is housed in a flat closed container in which a bottomed cylindrical positive electrode container 2 is caulked and fixed to a bottomed cylindrical negative electrode container 1 via an insulating gasket 3.
The electrode group 4 has a structure in which a positive electrode 5 and a negative electrode 6 are wound in a flat shape with a separator 7 interposed therebetween. The positive electrode 5 is exposed on one surface of the surfaces of the electrode group 4 having the largest area and is in contact with the inner surface of the positive electrode container 2. The negative electrode 6 is exposed on the other surface and is in contact with the inner surface of the negative electrode container 1.

[0051]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 2 is a sectional view showing an electrolytic solution impregnation process in the coin type nonaqueous electrolyte secondary battery of Example 1, and FIG. 3 is an electrode group used in the thin nonaqueous electrolyte secondary battery of Example 3 and 4 is a perspective view showing a laminate film, FIG. 4 is a plan view showing a laminate pack used in a gelling process of a thin non-aqueous electrolyte secondary battery of Example 3, and FIG. 5 is a thin non-aqueous electrolyte secondary battery of Example 3. It is sectional drawing which shows the gelation process of the following battery.

Example 1 <Production of Positive Electrode> Polyvinylidene fluoride (product name: # 110 manufactured by Kureha Chemical Industry Co., Ltd.) was added to 25 parts by mass of N-methylpyrrolidone.
0) After dissolving 3 parts by mass, 89 parts by mass of LiCoO ₂ having an average particle size of 3 μm as a positive electrode active material and 8 parts by mass of graphite (trade name: KS6 manufactured by Lonza Co.) as a conductive material were added, and a dissolver and a A bead mill was used to stir and mix to prepare a positive electrode slurry. This slurry was applied on both sides of an aluminum foil having a thickness of 15 μm as a current collector at regular intervals using a die coater, dried, pressed, and slit to obtain a reel-shaped positive electrode.

<Preparation of Negative Electrode> 10 parts by mass of graphite powder (trade name: KS15 manufactured by Lonza Co.) was added and mixed with 100 parts by mass of carbon fiber powder of mesophase pitch type (manufactured by Petka Co.), and styrene / Butadiene latex (trade name: L1571, manufactured by Asahi Kasei Corporation, solid content 4)
4.2 parts by weight and carboxymethyl cellulose as a thickening agent (trade name: BSH12 manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.)
Aqueous solution (solid content 1% by weight) of 130 parts by mass and distilled water 2
0 parts by mass was added and mixed to prepare a slurry. This slurry was applied on both sides of a copper foil having a thickness of 10 μm at regular intervals using a die coater, dried, pressed, and slit to obtain a reel-shaped negative electrode.

<Preparation of Electrode Group> After the lead tabs were joined to the obtained reel-shaped positive electrode and negative electrode, respectively, the positive electrode and the negative electrode were spirally wound with a polyethylene porous film as a separator using a winding machine. . Then, an electrode group was obtained by press molding into a flat shape so that the positive electrode was exposed on one surface and the negative electrode was exposed on the other surface.

<Preparation of Non-Aqueous Electrolyte> Ethylene carbonate (EC) and γ-butyl lactone (γ-BL) were mixed at a volume ratio of 1: 3, and L was used as an electrolyte in the obtained mixed solvent.
A non-aqueous electrolytic solution was prepared by dissolving iBF ₄ at 1.5 mol / L.

<Impregnation of Non-Aqueous Electrolyte> As shown in FIG.
A plurality of electrode groups 9 were housed in a bag-shaped container 8 made of a laminated film having a thickness of 0.15 mm in which nylon, aluminum foil and a heat-fusible resin film were laminated in this order from the outermost layer. Next, after injecting 1 g of the electrolyte solution per battery, 1
The pressure was reduced to 300 Pa (10 Torr), the pressure was maintained for 5 minutes, and the opening of the container 8 was sealed by heating while the pressure was reduced to obtain a laminate pack. The thickness T (thickness of the container for impregnation) with this laminated pack sandwiched between holders
Was fixed at 4.5 mm. With the thickness T fixed, the laminate pack was left in a pressurized atmosphere of 0.5 MPa for 5 minutes to impregnate the electrode group with the nonaqueous electrolytic solution.

<Assembly of Battery> After removing the electrode group from the laminate pack, the excess electrolytic solution adhering to the surface of the electrode group is wiped off, and then the weight of the electrode group is measured to determine the electrolytic solution content. The result is calculated (battery 10
The average value of each is shown in Table 1 below.

The battery container has a size of 2450 (diameter is 24 m).
m, and the height was 5 mm). The electrode group was housed in the negative electrode container so that the negative electrode surface was in contact with the inner surface of the negative electrode container. An annular insulating gasket was attached to the open end of the positive electrode container. Then, the positive electrode container is caulked and fixed to the negative electrode container to have the structure shown in FIG.
A coin type non-aqueous electrolyte battery having a design capacity of 100 mAh was obtained.

<Initial Charging Step> After assembly, the assembly was stored at room temperature for 24 hours and then subjected to constant current and constant voltage charging at 20 mA and 4.2 V for 8 hours to perform initial charging.

Example 2 <Preparation of Gel Electrolyte Precursor> A polyfunctional methacrylate (compound containing a plurality of functional groups represented by the following chemical formula 1) as a gel precursor, and a peroxide as a polymerization initiator were prepared. A gel electrolyte precursor was prepared by mixing with the same non-aqueous electrolyte solution as described above. The blending amount of each component is (non-aqueous electrolyte) :( gelling agent) :( peroxide) = 100: 6:
It was set to 0.12.

[0062]

[Chemical 1]

<Impregnation of Gel Electrolyte Precursor> A plurality of electrode groups were housed in a bag-shaped container made of a laminated film similar to that described in Example 1. Next, after injecting 1 g of the gel electrolyte precursor per battery, 1300 Pa (10 Torr)
The container was kept under reduced pressure for 5 minutes, and continuously, the opening of the container was sealed by heating while keeping the reduced pressure to obtain a laminate pack. The laminate pack was sandwiched between holders and the thickness T (thickness of the impregnation container) was fixed to 4.5 mm.
The gel electrolyte precursor was gelated by holding the laminate pack in an atmosphere of 80 ° C. for 1 hour while fixing the thickness T.

<Assembly of Battery> After taking out the electrode group from the laminate pack, the excess gel electrolyte adhering to the surface of the electrode group was wiped off, and then the gel electrolyte content was obtained from the weight of the electrode group. (Average value of 10 batteries) is shown in Table 1 below.

A flat type battery container having the same size as in Example 1 was prepared. The electrode group was housed in the negative electrode container so that the negative electrode surface was in contact with the inner surface of the negative electrode container. An annular insulating gasket was attached to the open end of the positive electrode container. Then, the positive electrode container is caulked and fixed to the negative electrode container, so that
A coin type non-aqueous electrolyte battery having a structure shown in and a design capacity of 100 mAh was obtained.

The secondary battery thus obtained was left for 24 hours under the same conditions as described in Example 1 and then subjected to initial charging.

(Example 3) <Production of electrode group> An aluminum tab 10 having a thickness of 0.05 mm and a width of 4 mm was connected to the same reel-shaped positive electrode as described in Example 1, and the same operation was performed. To the same negative electrode as described in Example 1, a copper tab 11 having a thickness of 0.05 mm and a width of 4 mm was connected. Using a winding machine, the positive electrode and the negative electrode were spirally wound with a polyethylene porous film as a separator. Then, the electrode group 12 having the structure shown in FIG. 3 was obtained by press molding into a flat shape.

<Impregnation of Gel Electrolyte Precursor> A laminate film 13 similar to that described in Example 1 was folded in two to form an electrode group 12 with a positive electrode tab 10 and a negative electrode tab 11.
Was extended to the outside of the film, and the opposing portion of the film was heat-sealed except for the gel electrolyte precursor injection port. Then, after injecting 1 g of the gel electrolyte precursor,
The pressure was reduced to 1300 Pa for 5 minutes, and subsequently the inlet was heated and sealed while the pressure was reduced to obtain a laminate pack. This laminated pack is holder 1
The thickness T ₁ (thickness of the container for impregnation) is 4.6 mm by sandwiching
Fixed to. The gel electrolyte precursor was gelated by keeping the laminate pack in an atmosphere of 80 ° C. for 1 hour while fixing the thickness T ₁ .

<Assembly of Battery> After taking out the electrode group from the laminate pack, the excess gel electrolyte adhering to the surface of the electrode group was wiped off, and then the gel electrolyte content was obtained from the weight of the electrode group. (Average value of 10 batteries) is shown in Table 1 below.

A laminated film similar to that described in Example 1 was coated on the electrode group so that the positive electrode tab and the negative electrode tab extended to the outside of the film, and the four sides of the film were heat-sealed to have a design capacity of 100 mAh. A thin non-aqueous electrolyte secondary battery of was obtained. When sealing one side out of the four sides of the film, it was performed under a reduced pressure atmosphere so that no gas remained in the film.

The secondary battery thus obtained was left for 24 hours under the same conditions as described in Example 1 and then subjected to initial charging.

Example 4 A thin nonaqueous electrolyte battery was manufactured in the same manner as described in Example 3 except that the initial charging was performed under the conditions described below.

<Initial Charging Step> After assembly, the battery was stored at room temperature for 24 hours, and then the battery was sandwiched by the holder again to fix the thickness T ₁ (battery thickness) to 4.7 mm. With the thickness T ₁ fixed, the battery was charged at 20 mA and 4.2 V at a constant current and constant voltage for 8 hours.
The first charge was given by doing for a while.

(Comparative Example 1) After the electrode group produced in the same manner as described in Example 1 above was housed in the negative electrode container, the same non-aqueous electrolyte solution as described in Example 1 was applied to 0. .4
g, 0.5 g, and 0.6 g were injected. Then, after crimping and fixing the positive electrode container to the negative electrode container via an insulating gasket,
By holding the electrode group at room temperature for 24 hours, the nonaqueous electrolytic solution was permeated into the electrode group to obtain a coin type nonaqueous electrolyte battery having the structure shown in FIG. 1 and a designed capacity of 100 mAh. Subsequently, initial charging was performed under the same conditions as described in Example 1.

The content of the electrolytic solution in the electrode group was calculated from the weight of the electrode group after disassembling the battery before charging, which was left standing at room temperature for 24 hours, and wiping off the electrolytic solution adhering to the outer periphery of the electrode group. .

(Comparative Example 2) After the electrode group prepared in the same manner as described in Example 1 was housed in the negative electrode container, the same gel electrolyte precursor as described in Example 2 was used. 0.4 g, 0.5 g and 0.6 g were injected. Next, the positive electrode container was caulked and fixed to the negative electrode container via an insulating gasket, and then kept at room temperature for 24 hours to allow the gel electrolyte precursor to permeate the electrode group. Then, the gel electrolyte precursor was gelated by heating at 80 ° C. for 1 hour to obtain a coin-type non-aqueous electrolyte battery having the structure shown in FIG. 1 and a designed capacity of 100 mAh. Next, initial charging was performed under the same conditions as described in Example 1.

The content of the gel electrolyte in the electrode group was calculated from the weight of the electrode group after disassembling the battery before the initial charging, wiping off the gel electrolyte adhering to the outer periphery of the electrode group.

(Comparative Example 3) An electrode group similar to that described in Example 3 was covered so that the positive electrode tab and the negative electrode tab extended to the outside of the film, and the opposing portions of the film were covered with the gel electrolyte precursor. Heat sealing was performed except for the inlet. Next, after injecting 0.4 g, 0.5 g, and 0.6 g of the same gel electrolyte precursor as that described in Example 2, the injection port was sealed by heating. The injection port of the film was sealed under a reduced pressure atmosphere so that no gas remained in the film. The gel electrolyte precursor was permeated into the electrode group by allowing it to stand at room temperature for 24 hours, and then sandwiched between holders to fix the thickness to 4.7 mm. By holding the laminate pack in an atmosphere of 80 ° C. for 1 hour while fixing the thickness, the gel electrolyte precursor was gelated, and a thin non-aqueous electrolyte battery having a designed capacity of 100 mAh was obtained. Next, initial charging was performed under the same conditions as described in Example 1.

The content of the gel electrolyte in the electrode group was calculated from the weight of the electrode group after disassembling the battery before initial charging and wiping off the gel electrolyte adhering to the outer periphery of the electrode group.

(Comparative Example 4) A thin nonaqueous electrolyte secondary battery was manufactured in the same manner as in Comparative Example 3 described above except that gelation was performed while the thickness of the impregnation container was not fixed.

[0081]

[Table 1]

As is clear from Table 1, when the outer package also serves as an impregnation container as in Comparative Examples 1 to 4, Example 1 in which the electrode group was immersed in the electrolytic solution unless an excessive amount of electrolytic solution was injected
It can be seen that the same amount of electrolytic solution as in the case of ˜4 cannot penetrate into the electrode group. Further, it can be seen that even if the amount of injected liquid is increased to 0.6 g, the electrolyte solution content of the electrode group is not so different from the case where the amount of injected liquid is 0.5 g.

In the following performance evaluation, for Comparative Examples 1 to 4, the amount of injected liquid was 0.4 to 0.6 g, and the amount of injected liquid was 0.5.
g, and the electrolyte content in the electrode group is from Example 1
It was set to be almost equal to 4. Here, in order to make the electrolyte content in the electrode group almost constant, the liquid injection amount was 0.
Although 5 g of the comparative example is used for the evaluation test, the amount of the electrolytic solution can be reduced by preliminarily permeating the nonaqueous electrolytic solution or the gel electrolyte precursor into the electrode group as in Examples 1 to 4. Therefore, it is considered to be industrially advantageous.

<Evaluation Test> Examples 1 to 4 and Comparative Examples 1 to 1
For the secondary battery of No. 4, after constant-current constant-voltage charging of 1.0 C and 4.2 V was performed for 3 hours, constant-current discharging of 0.2 C and discharge end voltage of 3.0 V was performed, and the discharge capacity at that time was measured. 0.2
The C discharge capacity is shown in Table 2 below. Next, after constant-current constant-voltage charging of 4.2 V at 1.0 C was performed for 3 hours, 1.0
A constant current discharge with C and discharge end voltage of 3.0 V was performed, and the discharge capacity at that time is shown as 1 C discharge capacity in Table 2 below. Also,
The discharge capacity at 1 C when the discharge capacity at 0.2 C is 100% is shown in Table 2 below as load characteristics.

Further, the internal resistances of the secondary batteries of Examples 1 to 4 and Comparative Examples 1 to 4 were measured by an alternating current method of 1 kHz, and the results are shown in Table 2 below.

The secondary batteries of Examples 1 to 4 and Comparative Examples 1 to 4 were charged with a constant current and constant voltage of 1.0 C and 4.2 V for 3 hours and then stored at 60 ° C. for 1 month. After storage, observe the appearance, then perform constant-current discharge at 1C ending with 3.0V, and then perform constant-current constant-voltage charging at 1.0C and 4.2V again for 3 hours, and then measure the battery thickness. did. The battery thickness obtained was compared with the battery thickness before storage and the results are shown in Table 2 below.

[0087]

[Table 2]

In the batteries of Examples 1 and 2 and Comparative Examples 1 and 2 using the flat type battery container such as the coin type, the appearance was changed by storage. In Comparative Examples 1 and 2, white particles were observed on the insulating gasket. The white particles are
It was found to be an electrolytic solution by the battery disassembly investigation and the component analysis of the deposit. When the electrolyte attached to the surface of the battery adheres to the electric circuit, there is a risk that the circuit may be broken or short-circuited due to corrosion. On the other hand, in the batteries of Examples 1 and 2, there was no change in the appearance after storage, and it was found that the insulating gasket was not contaminated with the electrolytic solution.

Comparing Example 3 using a laminated film container with Comparative Example 3, the battery of Example 3 has higher load characteristics and less change in thickness after storage than the battery of Comparative Example 3. Recognize. When the batteries of Example 3 and Comparative Example 3 were disassembled, it was found that Comparative Example 3 had larger charging unevenness. It is known that the active material used in the examples expands during charging and contracts during discharging. When the non-aqueous electrolyte solution or the gel electrolyte precursor is evenly permeated into the electrode group, the electrode reaction proceeds uniformly and the electrode thickness changes uniformly. Conceivable.

On the other hand, in Comparative Example 3 in which the distribution of the electrolytic solution is not uniform, the reactivity inside the electrodes is different, so that the expansion reaction of the electrode group partially progresses and the battery is deformed. A secondary adverse effect of the deformation of the battery is that the distance between the electrodes becomes uneven. It is considered that the internal resistance increases in the portion where the distance between the electrodes is widened and the reaction becomes difficult, and the nonuniformity of the electrode reaction described above further progresses. Example 1
By preliminarily permeating the electrolytic solution into the electrode group as in No. 4, it is possible to stabilize the battery shape and the battery characteristics.

Comparative Example 4 is an example in which the electrode group was not fixed during gelation after the electrode group was injected into the gel electrolyte precursor. According to this Comparative Example 4, the distance between the electrodes is not equidistant, and the electrode reaction is unevenly generated as in Comparative Example 3, so that the shape of the battery is deformed and the battery performance is deteriorated.

It can be seen that in the battery of Example 4, the initial charging was performed while fixing the battery thickness to a fixed size, so that the load characteristics were excellent and the internal resistance was low as compared with Example 3.

In the above-mentioned embodiment, the example in which the invention is applied to the secondary battery has been described, but the invention can be similarly applied to the primary battery.

[0094]

As described above in detail, according to the present invention, it is possible to provide a method for manufacturing a non-aqueous electrolyte battery having excellent load characteristics.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of a non-aqueous electrolyte secondary battery (for example, a coin type non-aqueous electrolyte secondary battery) manufactured by a method according to the present invention.

2 is a cross-sectional view showing an electrolytic solution impregnation step in the coin-type nonaqueous electrolyte secondary battery of Example 1. FIG.

FIG. 3 is a perspective view showing an electrode group and a laminate film used in the thin non-aqueous electrolyte secondary battery of Example 3.

FIG. 4 is a plan view showing a laminate pack used in the gelling process of the thin non-aqueous electrolyte secondary battery of Example 3.

FIG. 5 is a cross-sectional view showing a gelling process of the thin non-aqueous electrolyte secondary battery of Example 3.

[Explanation of symbols]

1 ... Negative electrode container, 2 ... Positive electrode container, 3 ... Insulation gasket, 4 ... electrode group, 5 ... Positive electrode, 6 ... Negative electrode, 7 ... Separator, 8 ... Film impregnation container, 9 ... Electrode group.

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Claims (2)

[Claims] 1. A step of accommodating an electrode group having a shape in which a laminate including a positive electrode and a negative electrode is wound or bent into a flat shape in an impregnation container made of film, and non-aqueous electrolysis in the impregnation container. A step of injecting a liquid, a step of decompressing the inside of the impregnating container, a step of closing the impregnating container, a step of applying a pressure from the outside to the impregnating container, and a step taken out from the impregnating container And a step of sealing the electrode group in a film outer casing or a flat outer casing. 2. A step of accommodating an electrode group having a shape in which a laminate including a positive electrode and a negative electrode is wound or bent into a flat shape in an impregnation container made of film, and a gel electrolyte precursor in the impregnation container. A step of injecting a body, a step of sealing the impregnating container, a step of gelling the gel electrolyte precursor while fixing the thickness of the impregnating container to a certain dimension, and taken out from the impregnating container. And a step of sealing the electrode group in a film outer casing or a flat outer casing.