JP3457624B2 - Method of manufacturing flat battery - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a flat battery such as a film-covered battery in which a power-generating element (elements related to power generation such as positive electrode, negative electrode, and electrolyte) is coated with a heat-fusible film. More specifically, the present invention relates to a method for manufacturing a square battery that is excellent in stability and is less likely to be deformed by charge and discharge due to repeated use.

[0002]

2. Description of the Related Art A battery using a thinly processed rectangular metal case as an exterior material and a battery using a thin flexible film such as a heat-fusible aluminum laminate film as an exterior material are advantageous in that they are lightweight and thin. It is rapidly spreading as a power source for electronic devices such as mobile phones, which are strongly demanded to be small and lightweight.

However, since the battery gradually deteriorates after repeated charging and discharging, the battery must be replaced after a certain number of times of use, and a battery having more repeated charging and discharging resistance (cycle stability) is required. .

One of the causes of repeated charge and discharge deterioration is deformation of the power generation element. In particular, in the case of a battery packaged with a heat-fusible film, the film itself does not have the ability to suppress the deformation of the power generation element as compared to the metal can case, and there is a problem that even a slight expansion of the power generation element or deformation of the power generation element causes deformation. there were. Generally, in order to improve the battery characteristics such as energy density, capacity, current density, impedance, and cycle life, the positive electrode active material and the negative electrode active material are in intimate contact with each other through the separator and are in uniform contact with each other. This is very important. Therefore, when the power generation element expands or deforms, the impedance increases, the discharge capacity decreases, and the charge / discharge cycle characteristics deteriorate.

With respect to this problem, the present inventors have prepared a battery in which an electric power generating element is covered with a heat-fusible film in an unpublished application (Japanese Patent Application No. 11-209401) at the time of the present application. After that, a method was proposed in which pre-charging was performed at least once or more while applying pressure to suppress deformation due to charge / discharge due to subsequent use. It is considered that the film-sheathed battery manufactured by this method has an internal strain averaged over the entire battery, which is averaged over the entire battery, and is suppressed from being deformed in subsequent charging and discharging. Therefore, the collector and the electrode layer or the electrode layer and the separator are separated or the separator is broken due to the deformation of the power generation element, and the resulting increase in impedance, reduction in capacity and charge / discharge efficiency, internal short circuit, etc. It is possible to produce a film-clad battery having excellent stability and safety.

[0006]

DISCLOSURE OF THE INVENTION The present invention provides a further improved method for carrying out a method of charging while applying pressure after manufacturing such a battery (hereinafter referred to as a pressurized precharging method). To do.

That is, the present invention provides a method for manufacturing a flat battery which is less likely to be deformed by charge and discharge and which is less likely to be deformed or broken even when the internal pressure rises and which is excellent in stability. To aim. It is another object of the present invention to provide a manufacturing method that reduces variations in quality even when a plurality of batteries are simultaneously subjected to a pressure charging method using a single pressure device having a simple structure.

[0008]

According to the present invention, one or more flat type batteries are sandwiched between a pair of press plates provided with a buffer layer on at least one side, and the flat type batteries are added with a space between the press plates. The present invention relates to a method for manufacturing a flat battery, which comprises at least one preliminary charging step in which charging is performed while applying pressure while fixing the pressure at fixed intervals.

As the buffer layer, for example, a sheet-shaped rubber elastic body is used. Further, the buffer layer may be composed of at least two layers of a high hardness layer and a low hardness layer, in which case the high hardness layer is arranged so as to be in contact with the flat battery. At that time, a sheet-shaped rubber elastic body is preferable as the low hardness layer, and a metal sheet or a resin sheet which is harder than the low hardness layer is preferable as the high hardness layer.

Further, in the present invention, in the preliminary charging step,
It is particularly advantageous when a plurality of flat type batteries are sandwiched between the pair of press plates to simultaneously manufacture a plurality of flat type batteries.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION As described above, the present inventor suppresses deformation due to charge and discharge due to subsequent use by performing precharging while applying pressure at least once after manufacturing a battery (pressurized precharging). I found that I can do it. However, it has been found that when applying this method to a plurality of flat type batteries, further consideration needs to be given to the pressurizing device and the like.

That is, if excessive pressure is applied to the power generating element during the pressurized precharging, the electrode layer and the separator may be damaged. For example, when a film-clad battery is directly sandwiched between a pair of rigid flat plates without providing a buffer layer, and a pressurization charging method is performed using a device that fixes the pair of flat plates at regular intervals, charging (or charging / discharging) Along with this, a force that causes the battery to swell is exerted, so that the applied pressure gradually increases, and excessive pressure may be applied to the power generation element. In order to prevent excessive pressure from being applied to the battery, it is preferable to provide the pressurizing device with pressure buffering means.

Further, in the case of applying the pressure pre-charging method to a plurality of batteries for mass production, if a plurality of batteries are arranged in a plane between a pair of rigid flat plates and pressure is applied simultaneously, Power concentrates on the thickest battery, and weakens on other batteries. In other words, the effect of the pressure charging method varies due to slight variations in the battery thickness,
There is a risk of increasing the variation in quality. This variation can be prevented by separately providing a flat plate for each battery, but in that case, means for applying pressure to the flat plate is also required individually, which complicates the apparatus.

Therefore, in the present invention, the flat type battery is sandwiched between a pair of press plates having a buffer layer on at least one side to apply a pressure charging method, so that the battery is charged (or charged / discharged). It is possible to prevent excessive pressure from being applied to the power generation element even if the force of swelling acts.

Even when a plurality of batteries are precharged under pressure, the buffer layer alleviates a slight variation in the thickness of the batteries and evenly applies a force to the plurality of batteries, so that there is little variation in quality. A flat battery can be obtained.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 schematically shows an example of an apparatus for carrying out the method of the present invention. Upper press plate 1
The lower press plate 2 is fixed by a spacer 4 and a screw 3 at a constant interval. On the lower press plate 2, a plurality of film-covered batteries 7 in which a winding-type and flat-shaped power generating element is covered with a film are placed, and a buffer layer 56 including a high hardness layer 6 and a low hardness layer 5. Is pressed by the upper press plate 1 to which is attached. The high-hardness layer 6 is in contact with the plurality of film-sheathed batteries 7 so as to straddle it, and the high-hardness layer 6 is a low-hardness layer 5 having substantially the same size (a size that spans a plurality of film-sheathed batteries). The low hardness layer 5 is attached to the upper press plate 1. Here, the high hardness layer 6 has, for example, a thickness of several hundred μm.
Made of deformable, hard and thin material such as metal sheet of
The low hardness layer 5 is made of, for example, a sheet-shaped rubber elastic body having a thickness of several mm. The distance between the upper press plate 1 and the lower press plate 2 is set so that the low hardness layer 5 is slightly contracted, and the film-covered battery 7 is separated from the lower press plate 2 by the restoring force of the contracted low hardness layer. A pressing force is applied to the high hardness layer 6.

In this structure, the low hardness layer is deformed in response to a slight difference in the thickness of the individual film-encased battery (the high hardness layer is also deformed at this time), and therefore, it is strong only for the thickest film-encased battery. It is possible to apply pressure in response to variations in the thickness of each battery without applying pressure or running out of pressure on the thinnest film-covered battery. Moreover, a pair of press plates, a fixing means composed only of spacers and screws, and a rubber sheet,
Since it is possible to pressurize a plurality of film-clad batteries at the same time by using one metal sheet, it is possible to simultaneously pressurize a large number of flat type batteries with a simple device.

Here, it is preferable that the upper press plate and the lower press plate have sufficient rigidity so as not to be deformed by pressure, and the material is preferably metal.

The thickness of the low hardness layer is not particularly limited, but if it is too thin, the pressure buffering effect cannot be obtained, so 0.1 mm or more is preferable. The upper limit of the thickness is not particularly limited and is, for example, 50.
Although it may be about mm, it is generally 30 mm or less. As for the hardness of the low hardness layer, for example, in the case of a rubber sheet having a thickness of 5 mm, the hardness at which a shrinkage of 0.01 mm to ³ mm occurs when a stress of 1 × 10 ⁻³ N / m ² is applied, preferably 0. A hardness at which shrinkage of 1 mm to 1 mm occurs is preferable. Materials include urethane rubber, foamed urethane rubber, fluororubber such as vinylidene fluoride-hexafluoropropylene copolymer, silicone rubber, silicone sponge rubber, SBR, NBR, natural rubber, EPDM, chloroprene rubber, nitrile rubber, acrylic rubber. Various rubbers can be used. In addition, sponge bodies of various polymers and air bags can be used.

The high hardness layer 6 provided in the example of FIG. 1 is preferably harder than the low hardness layer 5 and has a thin sheet shape. Further, it is preferable that the surface is flat.
Examples of usable materials include resin sheets of polyester, polypropylene, polyethylene, acrylic resin, silicone resin, and the like, and metal sheets. Further, among the various rubber materials that can be used for the low hardness layer, any material that is harder than the low hardness layer can be used for the high hardness layer.

The high hardness layer 6 has the following effects. For example, in a film-clad battery that houses a winding-type and flat-shaped power generation element, the portion of the bent portion 8 (see FIG. 2) of the electrode sheet is charged in the thickness direction of the battery more than other portions due to charging. Since the film is swellable and the outer casing is a flexible film, this portion easily swells locally even in the outer shape of the battery. The occurrence of such local swelling is not preferable when the battery is stored in a narrow storage space in the electronic device, and the battery surface is preferably flat. The presence of the high-hardness layer 6 in the pressurizing device can suppress local bulging of the battery, and can maintain the flatness of the surface of the film-clad battery even after charging. Moreover, by forming the high-hardness layer 6 into a thin sheet shape, it is possible to follow the deformation of the low-hardness layer 5 corresponding to the slight difference in the thickness of the individual film-clad batteries and to deform the battery. That is, it is possible to both suppress small-sized battery deformation such as local swelling in the battery and flexibly cope with a difference in thickness at a distant place such as a difference in thickness between batteries.

The thickness of the high hardness layer is preferably 0.05 to 1 mm in the case of a metal sheet, for example. In the case of a metal sheet, if it is too thin, the flexibility becomes excessive and local swelling in the battery cannot be sufficiently suppressed. In the case of a metal sheet, if it is too thick, the deformation of the metal sheet cannot cope with the difference in thickness between batteries, the strongest force is applied to the thickest battery, and the weak force is applied to other batteries. Even a slight variation in the thickness of the battery causes variations in the effect of the pressure charging method, which causes an inconvenience of increasing the variation in quality. When the high hardness layer is a resin sheet, it is preferably about 0.1 to 5 mm. When the high-hardness layer is a metal sheet, a protection member for preventing a short circuit may be provided on the metal sheet portion located at the electrode lead of the battery placement planned portion. Further, the high hardness layer and the low hardness layer may be adhered to each other and integrated, or may not be integrated.

In FIG. 1, the upper or lower press plate may be provided with connection terminals to the electrode leads of the battery.

The buffer layer may be provided between the upper press plate and the planned battery placement portion, between the lower press plate and the planned battery placement portion, or both.

In the above example, the buffer layer is composed of the high hardness layer and the low hardness layer. However, the buffer layer may have only one layer, and the material constituting the layer at that time is as described above. The rubber elastic material mentioned as the low hardness layer is preferable.

In the above-mentioned example, the film-covered battery is used. However, a battery covered with a rectangular metal can, a rectangular resin case, or the like is not limited as long as the pressure can be externally transmitted to the power generating element. For example, the effect of the present invention can be obtained.

In the above example, a battery having a wound type power generating element is used for explanation, but a battery having another structure such as a battery having a flat plate electrode laminated type power generating element can be repeatedly charged and discharged. The effect of the present invention can be obtained for a battery in which internal strain such as deformation of a power generation element occurs and performance gradually deteriorates.

The power generating element used in the flat battery of the present invention contains a known material such as a positive electrode, a negative electrode, an electrolyte, and if necessary, a separator, and is, for example, as follows.

For example, the positive electrode is not particularly limited as long as it absorbs positive ions or discharges negative ions during discharge, and LiMnO ₂ , LiMn ₂ O ₄ , Li
Conventionally known materials such as metal oxides such as CoO ₂ and LiNiO ₂ and conductive polymers such as polyacetylene, polyaniline, polypyrrole, polythiophene, polyparaphenylene and their derivatives, and disulfide compounds can be used as positive electrode materials for secondary batteries. .

The negative electrode is not particularly limited as long as it is a material capable of occluding and releasing cations, and crystalline carbon such as graphitized carbon obtained by heat-treating natural graphite, coal or petroleum pitch at high temperature, Conventionally known negative electrode active materials for secondary batteries can be used, such as amorphous carbon obtained by heat treatment of coal, petroleum pitch coke, acetylene pitch coke, and the like, lithium alloys such as metallic lithium and AlLi, and the like.

Further, in the present invention, when forming an electrode, these electrode active materials may be mixed with an appropriate binder or a functional material to form an electrode layer. As the binder, a halogen-containing polymer such as polyvinylidene fluoride is used, and as the functional material, acetylene black or polypyrrole for ensuring electron conductivity, a conductive polymer such as polyaniline, and an ion conductive material are used. Examples of the polymer electrolyte include a polymer electrolyte and a complex thereof.

Although the current collector is not particularly limited, for example, a metal foil or a metal mesh having high conductivity and excellent malleability is used. As such a current collector, for example, an aluminum foil is preferable in the case of a positive electrode, and a copper foil is preferable in the case of a negative electrode,
The thickness is, for example, 5 to 50 μm. The active material is bonded to these current collectors with a binder.

As the electrolyte contained in the power generating element of the present invention, conventionally known materials such as electrolyte solution, polymer solid electrolyte, and polymer gel electrolyte can be used. The electrolyte salts contained in the electrolyte include ClO ₄ ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , CF ₃ SO ₃ ⁻ , (CF ₃ S
^{_{O 2) 2 N -, (}} C 2 F 5 SO 2) 2 N -, (CF 3 SO 2)
Examples thereof include alkali metal salts of Li, K, Na and the like of halogen-containing compound anions such as ₃ C ⁻ and (C ₂ F ₅ SO ₂ ) ₃ C ⁻ . These electrolyte salts can be used alone or in combination.

As the electrolyte solution, ethylene carbonate, propylene carbonate, butylene carbonate,
Non-aqueous electrolysis in which the above electrolyte salt is dissolved in a non-aqueous solvent such as dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, acetonitrile, dimethoxyethane, sulfolane, tetrahydrofuran, γ-butyrolactone, N-methyl-2-pyrrolidone, and dimethylformamide. A liquid is included.

Examples of the polymer solid electrolyte include polyether polymers such as polyethylene oxide and polypropylene oxide containing the above-mentioned electrolyte salts.

Further, as the polymer gel electrolyte, polyvinylidene fluoride, the above-mentioned electrolyte salt, and the solvents listed as the non-aqueous solvent usable for the above-mentioned non-aqueous electrolytic solution are used.
Fluorine-based polymers such as polyhexafluoropropylene and polytetrafluoroethylene; acrylate-based polymers such as polymethyl methacrylate and polymethyl acrylate; and polymers contained in polymers such as polyacrylonitrile. These solvents or polymers can be used alone or in combination. In particular, the polymer may be used as a composite compound by copolymerization or the like.

As the porous separator, a microporous separator is generally used, but a woven fabric or a non-woven fabric may be used as long as the effect of the present invention can be obtained. As the microporous separator, for example, a pore size of 0.1 to 5 μm
m, porosity 30 to 70%, and thickness 1 to 50 μm can be used. As a material of the separator, a polyolefin resin such as polyethylene or polypropylene, polyester, or the like can be used.

When the present invention is applied to a film-clad battery, the film used for the packaging is preferably a film capable of sealing the periphery after putting the power generating element therein, and a film capable of heat-sealing at least the sealing portion. Is preferred. For example, the entire film may be formed of a heat-fusible film made of a polyolefin resin such as polyethylene and polypropylene, or the film may have a multilayer structure if necessary and the innermost layer may be a heat-fusible resin layer.

A preferable example of such a multilayer film is at least three layers of a surface protective layer, an intermediate metal layer, and a heat-sealing layer, and the surface protective layer is a resin which does not melt at the heat-sealing temperature, such as polyethylene terephthalate. A resin layer such as nylon, nylon or polyimide is used. In addition, the intermediate metal layer has few cracks or pinholes, etc., and a metal that does not permeate various gases, for example, aluminum, nickel,
It is preferable to use a foil such as gold. In the present invention, the thickness of the intermediate metal layer is not particularly limited, but if it is too thin, pinholes are likely to occur.
Used in the range of 0.1 mm. As a heat-sealing layer, it is hard to be attacked by an electrolyte solution, is thermoplastic, and has a temperature of 150 to 250 ° C.
There is no particular limitation as long as it can be heat-sealed within the range, and polyolefin resins such as polyethylene and polypropylene, polyimide resins, ionomers, etc. are used.

It is also possible to increase the adhesive strength between the thermoplastic resin film and the metal foil by using an adhesive layer or by modifying the surface of the metal foil.

The manufacturing method of the present invention can be used in fields in which deformation or the like may occur when a voltage or current is applied in addition to the manufacturing of a secondary battery. Also in the manufacturing method of the electrolytic capacitor, various sensors, etc., a product with excellent stability can be manufactured by applying voltage or current while applying pressure with the pressurizing device of the present invention.

[0043]

EXAMPLES The details of the present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

Example 1 Lithium manganate powder having a spinel structure, carbonaceous conductivity-imparting material, and polyvinylidene fluoride were mixed and dispersed in NMP at a weight ratio of 90: 5: 5 to prepare a slurry. The amount of NMP was adjusted so that the slurry had an appropriate viscosity. Using a doctor blade, this slurry was used as a positive electrode current collector and had a thickness of 20 μm.
Apply evenly on one side of the aluminum foil, and
Vacuum dried for an hour. Similarly, the other surface was coated with the slurry and vacuum dried. This sheet was roll-pressed to form a positive electrode active material layer. Theoretical capacity is 600mA
It was set to h.

Next, amorphous carbon powder and polyvinylidene fluoride were mixed in NMP at a weight ratio of 91: 9, dispersed and stirred to obtain a slurry. The amount of NMP was adjusted so that the slurry had an appropriate viscosity. This slurry was used as a negative electrode current collector with a doctor blade and had a thickness of 10 μm.
Was evenly applied to one side of the copper foil and dried in vacuum at 100 ° C. for 2 hours. At this time, the theoretical capacity per unit area of the negative electrode layer and the theoretical capacity per unit area of the positive electrode layer were adjusted to be 1: 1. Similarly, the other surface was coated with the slurry and vacuum dried. This sheet was roll-pressed to form a negative electrode active material layer adhered to both surfaces of the negative electrode current collector.

A microporous separator (made by Hoechst Celanese Co., Ltd.) having a three-layer structure of polypropylene / polyethylene / polypropylene between the positive electrode and the negative electrode.
The thin elliptical electrode winding body was obtained by winding up through the Celgard 2300) using an elliptical winding core, and further hot pressing.

On the other hand, polypropylene resin (sealing layer, thickness 70 μm), polyethylene terephthalate (20 μm
m), aluminum (50 μm), and polyethylene terephthalate (20 μm) are laminated in this order, two laminated films are cut into a predetermined size, and one of them is fitted with the size of the above electrode winding body. A recess having a bottom surface portion and a side surface portion was formed. The electrode-wound body was wrapped so that they faced each other, and the periphery thereof was heat-sealed to produce a film-clad battery having a shape as schematically shown in FIGS. 2 and 3. A positive electrode lead 73 and a negative electrode lead 74 (collectively referred to as electrode leads) are connected to the electrode winding body in advance, and the electrode lead is pulled out when the periphery of the electrode winding body is heat-sealed with the laminate film 71. This part was heat-sealed so as to be sandwiched between the two. The electrode winding body was impregnated with the electrolytic solution before the last one side was heat-sealed. The last one side was other than the electrode lead heat-sealed portion. The electrode winding body impregnated with the electrolytic solution corresponds to the power generating element in FIG. The electrolyte was 1 M LiPF ₆ as a supporting salt, and a mixed solvent of propylene carbonate and ethylene carbonate (weight ratio 50:50) was used as a solvent. Thus, four film-clad batteries having a thickness of about 3.6 mm and a theoretical capacity of 600 mAh were produced.

Next, the pressurizing device of the present invention was assembled as shown in FIG. On the lower press plate 2 made of an aluminum plate having a thickness of 5 mm, four of the above film-clad batteries are arranged in two rows and two.
A 0.2 mm-thick stainless steel sheet having a size that straddled these four batteries was placed in a row, and a 5 mm-thick porous rubber sheet was further placed thereon.
This rubber sheet has a hardness that causes 0.5 mm of contraction when a stress of 1 × 10 ⁻³ N / m ² is applied. Next, an upper press plate made of an aluminum plate having a thickness of 5 mm was placed with a spacer in between and screwed. The thickness of the spacer was 0.3 mm smaller than the natural thickness of the battery / metal sheet / rubber sheet laminate. In this way, the film-clad battery was pressurized. The terminals from the charging / discharging device were previously connected to the electrode leads of the battery group.

With this pressure applied, each battery was heated to 112 mA.
Pre-charging was performed by charging to 4.2 V with a constant current of 4.2 V and then with a constant voltage of 4.2 V for a total of 10 hours.

Example 2 Four film-clad batteries were prepared in the same manner as in Example 1 and precharged in the same manner as in Example 1 except that the metal sheet was not provided. Spacer of the pressure device is 0.2 mm from the first embodiment
I made it small.

Comparative Example 1 Four film-covered batteries were prepared in the same manner as in Example 1 and precharged in the same manner as in Example 1 except that the metal sheet and the rubber sheet were not provided. It was The spacer of the pressurizer was smaller than that of Example 1 by 5.2 mm.

<Comparative Example 2> Four film-covered batteries were prepared in the same manner as in Example 1, and were left open without pressurization.
Each battery was charged to a constant current of 112 mA to 4.2 V, and then pre-charged at a constant voltage of 4.2 V for a total of 10 hours.

<Evaluation and Results of Battery> The battery preliminarily charged by each method as described above was removed from the pressurizing device, and a charge / discharge cycle test was conducted at 20 ° C. for 100 cycles. Charging was performed at 600 mA to 4.2 V, and discharging was performed at 600 mA to 3.0 V. Table 1 shows the measurement results of the battery thickness and capacity before and after the cycle test, and the observation results of the battery surface flatness. The minimum and maximum values of four batteries are shown.

[0054]

[Table 1]

The battery thickness after the pre-charging and the battery thickness after the cycle test were compared with Comparative Example 2 in which the pre-charging was performed without applying the pressure, and the pre-charging was performed using the pressurizing device of the present invention. The performed Examples 1 and 2 were thinner. Regarding the battery capacities after the cycle test, the capacities of Examples 1 and 2 were higher than those of Comparative Examples 1 and 2. From these results, it is understood that by performing the preliminary charging while applying pressure, the swelling during the subsequent use of the battery is suppressed and the capacity deterioration is also suppressed.
In Comparative Example 1, the swelling is suppressed, but the capacity deterioration is not suppressed. The details of this cause are not clear, but since the film-clad battery was directly sandwiched between the upper and lower press plates that were fixed at regular intervals without providing a buffer layer, a force that the battery tried to swell with charging, It is considered that the applied pressure gradually increased and excessive pressure was applied to the power generation element, and the electrode layer and the separator were damaged. In addition, the variation in the capacity of Comparative Examples 1 and 2 (width between the minimum value and the maximum value of the capacity of the four batteries) was 20 mAh, whereas in Examples 1 and 2, the variation was suppressed to 4 to 8 mAh. ing. This is because the electrode contact state and the thickness of the electrode winding body initially vary depending on the battery, and the variation appears as it is in Comparative Example 2, whereas the precharging using the pressurizing device of the present invention is performed. In Examples 1 and 2 performed, it is considered that variations in characteristics were reduced because pressure was applied corresponding to variations in thickness of individual batteries during precharging. In Comparative Example 1, since there was no buffer layer, the difference in the thickness of each battery caused the difference in the pressure applied to each battery, and the variation in the pressurizing effect occurred, so that the variation in capacity was larger than that in the Example. I think it was big. Further, when comparing Examples 1 and 2, Example 1 was superior to Example 2 in the degree of suppression of battery capacity variation after the cycle test, the degree of suppression of battery swelling, and the surface flatness. It is considered that this is because by installing the metal sheet between the rubber sheet and the film-clad battery, local bulging of the electrode winding body during precharging could be suppressed.

[0056]

According to the present invention, it is possible to provide a flat battery which is less likely to be deformed or broken even when the internal pressure rises due to a small amount of deformation due to charge and discharge, and which is excellent in stability.

In particular, even when the pressure charging method is applied to a plurality of batteries at the same time, the pressure can be applied corresponding to the variation in the thickness of each battery, and the variation in the battery characteristics after the application of pressure can be suppressed. Can be reduced. Further, as a means thereof, it can be realized by using a pressurizing device having a simple structure, which is advantageous in terms of cost.

Further, according to the present invention, deformation of a small-sized battery such as local swelling in the battery is suppressed (battery flatness).
In addition, since it is possible to achieve both flexibility in responding to the difference in thickness at a distant place such as difference in thickness between batteries, it is possible to satisfy variations in battery characteristics and flatness during use at the same time. .

[Brief description of drawings]

FIG. 1 is a diagram schematically showing a pressurizing device when pressurizing and precharging a plurality of film-clad batteries.

FIG. 2 is a diagram schematically showing a cross section of an example of a film-clad battery.

FIG. 3 is a diagram schematically showing an overall view of an example of a film-clad battery.

[Explanation of symbols] 1 Upper press plate 2 Lower press plate 3 screws 4 spacers 5 Low hardness layer 6 High hardness layer 56 buffer layer 7 Film exterior battery 71 Laminated film 72 Power generation element 73 Positive lead 74 Negative electrode lead 8 Electrode sheet bent part

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tomokazu Urauchi 5-7-1, Shiba, Minato-ku, Tokyo Inside NEC Corporation (72) Inventor Nobuhide Oyama 484 Harigaya-cho, Utsunomiya-shi, Tochigi NCE Mobile Energy Co., Ltd. (72) Inventor Ryuichi Shimizu 484 Harigaya-cho, Utsunomiya City, Tochigi Prefecture NMC Mobile Energy Co., Ltd. (72) Inventor Yu Sakauchi 5-7-1, Shiba, Minato-ku, Tokyo NEC Corporation (56) References JP-A-11-111339 (JP, A) JP-A-58-73968 (JP, A) JP-A-11-339853 (JP, A) JP-A-2001-35523 (JP, A) (58) ) Fields surveyed (Int.Cl. ⁷ , DB name) H01M 10/04 H01M 10/40

Claims (8)

(57) [Claims] 1. One or more flat type batteries covered with a heat-fusible film are sandwiched between a pair of press plates having a buffer layer on at least one side, and the spaces between the press plates are set to the front.
While fixed to a constant interval, which can pressurize the serial flat battery,
At least one pre-charging step of charging while applying pressure
A method of manufacturing a flat battery, comprising: 2. The method for manufacturing a flat battery according to claim 1, wherein the buffer layer is a sheet-shaped rubber elastic body. 3. The method for manufacturing a flat battery according to claim 1, wherein the buffer layer is composed of at least two layers of a high hardness layer and a low hardness layer, and the high hardness layer is arranged in contact with the flat battery. . 4. The method for manufacturing a flat battery according to claim 3, wherein the low hardness layer is a sheet-shaped rubber elastic body, and the high hardness layer is a metal sheet or a resin sheet. Wherein said flat battery method of producing a flat battery according to any one of claims 1-4 is intended to include non-aqueous electrolyte solution. Wherein said flat battery method of producing a flat battery according to any one of claims 1 to 5, intended to include a polymer solid electrolyte or polymer gel electrolyte. Wherein said flat battery is flat battery according to any one of claims 1 to 6 as it has a power generating element in which a cathode and an anode made by winding a flat shape via a separator Manufacturing method. 8. A plurality of flat type batteries covered with a heat-fusible film are sandwiched between a pair of press plates having a buffer layer on at least one side, and the flat type batteries are added with a space between the press plates. A method of manufacturing a flat battery, comprising a preliminary charging step of charging while applying pressure while fixing at a fixed interval that can be pressed.