JP2003272595A - Manufacturing method for electrochemical device, manufacturing equipment, and electrochemical device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method efficiently manufacturing an electrochemical device preventing shrinkage exceeding a fixed value even at temperature causing heat shrinkage, preventing short circuit between positive and negative sheets, not having bad effect on the ionic conductivity of a separator, having high safety causing no hard short-circuit and having high capacity, and to provide manufacturing equipment for the electrochemical device and to provide the electrochemical device. <P>SOLUTION: In the manufacture of the electrochemical device having a stacked body formed by stacking a positive electrode and a negative electrode through the separator, at least the positive electrode and/or the negative electrode are/is interposed between the separators, and when parts of the periphery parts of the separators are melt-bonded to form the bag-shaped separator, the width of the bonded part in the periphery part of the separator is specified to 0.3 mm or less. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrochemical device having stacked electrode pairs, particularly a lithium secondary battery, an electric double layer capacitor, and a manufacturing method and manufacturing apparatus therefor.

[0002]

2. Description of the Related Art With the widespread use of portable electronic devices, there has been a demand for electrochemical devices such as secondary batteries, which are small, lightweight, thin and capable of continuous operation for a long time. Conventional secondary batteries use a metal outer can, but by using a thin and light film for the outer body, it has become possible to reduce the battery weight and increase the degree of freedom in designing electronic devices.

The outer package used for such a battery is a film mainly made by laminating a plurality of resins on an aluminum foil. By using this aluminum laminate film, a battery using a conventional metal outer can can be used. It has become thinner and lighter.

However, if some abnormality occurs in a battery using such a film as an outer casing, heat or gas may be generated depending on the type of electrolyte used, and in the worst case, rupture or ignition may occur. It may reach. It is considered that the cause of rupture / ignition is that LiCoO ₂ , which is the active material of the positive electrode, tends to deteriorate in thermal stability as the potential increases. Especially, DSC results show 4.2V (compared with Li / Li +)
It is considered that LiCoO ₂ having a potential of has an exothermic peak near 210 ° C. to 220 ° C. and causes thermal runaway when the active material is heated above this temperature.

Generally, a lithium secondary battery used in a mobile phone uses a polymer separator in terms of weight and volume efficiency. The separator made of these polymers starts to shrink at around 90 ° C. and is heated to the melting point to melt. If the positive electrode and the negative electrode are short-circuited when the separator contracts, heat may be generated inside the battery and the active material may run into heat, causing rupture / ignition in the worst case, and the thermal behavior of the separator is also important.

As a method of forming an electrode group to be put in the outer package, there are a method of winding a long electrode and a method of laminating a large number of electrodes.

In the conventional wound-type battery, the electrode and the separator are stacked and wound, so that the separator is restrained by the electrode and shrinks only to a certain value.

However, although the winding method can be used as it is as an advanced type of a cylindrical battery, the shape of the battery is limited, and it is difficult to form a battery other than a cube, a rectangular parallelepiped or a cylindrical battery. In addition, when attempting to make a thin battery, the electrode may be cracked or broken due to winding, and therefore a thick and dense electrode cannot be used, which is disadvantageous in terms of energy density.

On the other hand, in the lamination method, the shape of the battery can be relatively freely set, and since it is not necessary to wind the electrode, a thick and high density electrode can be used, and a thinner and higher energy density battery can be manufactured. .

Further, the laminated structure has an advantage that the area ratio of the positive electrode and the negative electrode can be made constant, but in a simple laminated structure of the electrode and the separator, the separator contracts at 90 ° C. or higher, and the positive electrode and the negative electrode are short-circuited. There was a problem.

A number of proposals have been made for designing batteries that are hard to short-circuit by the lamination method. One of them is the bag construction method. JP-A-6-36801 and JP-A-9-2133
As disclosed in Japanese Patent Publication No. 77 and Japanese Patent Application Laid-Open No. 10-55795, an electrode is generally sandwiched between two separators, and then a peripheral portion is heat-sealed to form a bag-shaped electrode. create. Next, the electrodes are laminated and housed in a metal can or an exterior body to form a battery.

However, in covering the positive electrode or the negative electrode with the separator in a bag shape, there are at least two problems to be solved in the process.

[0013] One of them is that when the polymer-made separators are melt-bonded to each other in the periphery of the electrodes, it is necessary to bring a high-temperature heating element into contact with the separators, but local heating is difficult and the melt-bonding is performed. When the separator part other than the parts is heated, it contracts and closes the fine pores, which deteriorates the 2C characteristic which is the battery characteristic, and in severe cases, ion conduction cannot be performed and the battery function may be lost. Since it was difficult to carry out local melt bonding as described above, such a melt bonding method for a separator made of a polymer was not used.

The other one is that when the polymer-made separators are melt-bonded to each other in the peripheral portion of the electrode, if the melted area is large, wrinkles are generated in the separators or polymer masses are generated to improve the volume efficiency of the secondary battery. Not only is it lowered, but the distance between the positive electrode and the negative electrode is not uniform, which is a cause of deterioration in battery performance.

[0015]

SUMMARY OF THE INVENTION It is an object of the present invention to prevent shrinkage beyond a certain level even when the temperature at which heat shrinkage is reached does not occur, and there is no short circuit problem between the positive and negative electrode sheets, and the ion conductivity of the separator is adversely affected. It is an object of the present invention to provide a method and a manufacturing apparatus for efficiently manufacturing a high-performance electrochemical device which is excellent in safety and does not lead to a hard short circuit.

[0016]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention melts and bonds a separator made of a polymer around the electrode of a positive electrode or a negative electrode so that a heat radiating plate and By contacting the cooling plate and heating the parts other than the melting part as much as possible, it was possible to prevent the short-term prevention of the negative electrode and the positive electrode without lowering the ionic conductivity of the separator.

That is, the above object is achieved by the following constitution of the present invention. (1) In manufacturing an electrochemical device having a laminate in which a positive electrode and a negative electrode are laminated via a separator, at least the positive electrode and / or the negative electrode is sandwiched between the separators, and a part of peripheral portions of the separator are melt-bonded to each other. A method for producing an electrochemical device in which the width of the adhesive portion around the separator is set to 0.3 mm or less and melt-adhesion is performed when forming a bag shape. (2) A method for manufacturing an electrochemical device, in which the adhesive portion around the separator is within 1 mm from the outer peripheral portion of the electrode. (3) The method for producing an electrochemical device according to (1) or (2) above, in which the melt-bonding is performed by contacting the heat-dissipating member or the cooling member except for the melt-bonding portion to carry out the melt-bonding. (4) The method for manufacturing an electrochemical device according to any one of (1) to (3) above, wherein the fusion bonding is performed by pressing a heating element having a width of 0.3 mm or less. (5) An electrochemical device having a laminate in which a positive electrode and a negative electrode are laminated via a separator, wherein the positive electrode and / or the negative electrode is housed in a bag-shaped separator, and an adhesive portion around the separator is provided. Device with a width of 0.3 mm or less. (6) A manufacturing apparatus for manufacturing an electrochemical device having a laminated body in which a positive electrode and a negative electrode are laminated with a separator interposed therebetween, which has a heat-generating member for performing melt bonding to process the separator into a bag shape. This heat generating member is arranged on the outer peripheral portion of the heat generating member so that the portion corresponding to the positive electrode and / or the negative electrode sandwiched between the separators is hollow, and the width of the portion in contact with the separator is 0.3 mm or less. Device manufacturing equipment. (7) The apparatus for manufacturing an electrochemical device according to (6), wherein the heat generating member is arranged within 1 mm from the outer periphery of the positive electrode and / or the negative electrode sandwiched between the separators. (8) The apparatus for manufacturing an electrochemical device according to (6) or (7), further including a heat dissipation member or a cooling member that is in contact with other than the melt-bonded portion.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION In the production method of the present invention, in producing an electrochemical device having a laminate in which a positive electrode and a negative electrode are laminated via a separator, at least the positive electrode and / or the negative electrode is sandwiched between separators, When melt-adhering parts of the peripheral part of the separator to form a bag,
The width of the adhesive portion around the separator is 0.3 mm or less, and the melt adhesion is performed.

In this way, when the separator sandwiching the positive electrode and / or the negative electrode is heat-sealed, the width of the adhesive portion at the peripheral portion of the separator which is the outer peripheral portion of the positive electrode and / or the negative electrode is set to 0.3 mm or less. Therefore, without adversely affecting the ionic conductivity of the separator, it is possible to prevent wrinkles on the separator when melt-bonding, or to prevent deterioration of performance by generating polymer mass and lowering volumetric efficiency. You can

Further, according to the present invention, the separator is melted and adhered around the electrode of the positive electrode or the negative electrode, and the heat dissipation plate and the cooling plate other than the melt-bonded part are brought into contact with each other to reduce heating in the non-melted part as much as possible. It is possible to prevent the short circuit between the negative electrode and the positive electrode without lowering the ionic conductivity of.

The width of the heating element (heater) is preferably narrow in order to prevent the generation of lumps and wrinkles of the polymer separator. Further, it is desirable that the size of the heating element with respect to the electrode be within a certain range.

Specifically, the melt-bonding width of the separator is determined by the melt-bonding width of the heating element (heater). Therefore, the fusion bonding width of the heating element may be 3 mm or less, preferably 0.15 to 0.25 mm, more preferably 0.1 mm.
9 to 0.21 mm is good. Such a heating element (heater)
The fusion bonding width is usually the dimensional width of the heating element itself, and more specifically, can be adjusted by the plate thickness of the heater.

In the present invention, the outer dimensions of the heating element (heater) are within 1 mm, preferably 0.5 to 1 mm, larger than the electrode dimensions. Also, the dimensions of the polymer separator are the external dimensions of the heating element (outside the thickness of the heater)
It is desirable to make it larger by 0.2 to 0.5 mm.

Next, the method of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic perspective view showing an example of a manufacturing apparatus for carrying out the method of the present invention. As shown in the figure, the fusion bonding unit 1 elevates and lowers a main body 2 having a predetermined rigidity, a pressurizing elevating air cylinder 3 for elevating and lowering the entire unit 1 including the main body 2, and a cooling plate in a heater unit 5. It has a cooling plate elevating cylinder 4 and a seal heater unit 5 for melting and adhering the separator into a bag containing electrodes. In addition, the fusion bonding unit 1
A fixed suction cup unit 8 is arranged in the lower part of the table so that a separator or the like for fusion bonding can be adsorbed and fixed.

The heater unit 5 has, for example, as shown in FIG. 2, a sealing heater 51 formed in a flat C shape so that the separator can be melt-bonded in a bag shape, and the sealing heater is held from the inside. And a heater pressing member 52 for fixing the heater 51 to the holding member 53 from the outside. A cooling plate 54 for cooling the central portion of the holding member other than the melt-bonded portion of the separator is arranged slidably in the vertical direction with respect to the holding member 53. Further, there is a power feeding portion 55 at both ends of the heater 51, from which a pulsed current is supplied to heat the heater to perform the melt bonding work.

In order to perform the melt-bonding of the separator using such an apparatus, it is advisable to perform the following steps, for example.

(1) First, the polymer separator 11 is cut into a predetermined size, and is conveyed and supplied to the fixed sucker unit 8 by, for example, a uniaxial robot with a sucker (not shown). (2) Next, one negative electrode 12 is adsorbed by, for example, a uniaxial robot with a suction cup (not shown), and the electrode alignment is performed XY-
Supply to the θ table 7. (3) Electrode alignment XY- [theta] table 7 is driven by a pulse motor, a servomotor, etc., and the electrode position is confirmed by the electrode alignment camera 6, while the XY position is confirmed.
Correct the electrode position in the −θ direction. (4) The negative electrode 12 for which alignment has been completed is supplied from the table 7 onto the polymer separator 11 on the fixed suction cup unit 8 by a uniaxial robot with a suction cup. (5) Further, the polymer separator 11 is supplied onto the negative electrode 12 of the fixed suction cup unit 8 by the uniaxial robot with suction cup. With this, the negative electrode 12 is sandwiched between the two separators. (6) Next, the seal heater unit 5 is moved down by the pressurizing / lifting air cylinder 3, and pressure is applied on the electrode 12 sandwiched between the polymer separators 11. The cooling plate 54 in the seal heater unit 5 is constantly pressurized by the cooling plate elevating air cylinder in the seal heater unit 5. Therefore, the cooling plate 54 is retracted into the seal heater unit 5 by the thickness of the electrode due to the pressure of the heater pressure cylinder, and the polymer separator 11 and the electrode 12 are pressure bonded. (7) As a power source (not shown), for example, an impulse sealing machine is used to supply a pulsed current to the heater 51 to melt and bond the separators 11 to each other. (8) When the bonding is completed, the air cylinder for raising and lowering the heater unit is raised. At this time, the cooling plate 54
The bag-shaped electrode is pushed down by the stroke of, and the welded polymer separator is peeled off from the heater.

In this way, the bonding around the electrodes is easily performed, and the bag-shaped separator 11 accommodating the electrodes 12 is completed.

The bonding work by the method and apparatus of the present invention can easily form a bag-shaped separator without forming wrinkles or lumps on the separator, not only improving the performance of the battery but also improving the process efficiency. Can be manufactured well.
These methods and devices can also be applied to a wound battery.

Next, an electrochemical device to which the present invention is applied, particularly a lithium secondary battery will be described.

The electrochemical device of the present invention is an electrochemical device having an electrode pair in which a positive electrode and a negative electrode are laminated with a separator interposed therebetween, and at least a part of the peripheral portion of the separator of the laminate is adhered to each other to make it strong. Is integrated with.

Alternatively, it is an electrochemical device having a laminated body in which a positive electrode and a negative electrode are laminated with a separator interposed therebetween, wherein a heat-shrinkable film is arranged so as to surround an outer peripheral portion of the laminated body, and at least the laminated body. This is a structure in which the peripheral portions of the separator are adhered to each other and firmly integrated.

The electrochemical device thus obtained is not only resistant to stacking deviation, but also has good results in a predetermined heat resistance test called a hot oven and is excellent in safety.

Further, by integrating the laminated body, the handling property is facilitated, and the manufacturing process such as encapsulation in the outer package is simplified.

Next, the electrochemical device of the present invention will be described in more detail with reference to the drawings.

3 and 4 are a plan view showing a schematic structure of the electrochemical device of the present invention and a sectional view taken along the line AA '. The exterior body is omitted in each figure. In the figure, the laminate 22 has a structure in which positive electrodes 24, negative electrodes 25, and separators 23 are alternately laminated.

The size of the separator 23 is the positive electrode 2
4. It is larger than the electrode composed of the negative electrode 25, and is set so as to protrude to the periphery of the electrodes 24 and 25 when laminated.

The separator 23 is preferably an electrode 24,
It is formed in a bag shape so as to wrap around 25. Such a bag-shaped separator is formed by bending a single sheet, sandwiching the positive electrode and / or the negative electrode with this separator, and adhering the peripheral portion, or sandwiching the positive electrode and / or the negative electrode with two separators, and adhering the peripheral portion. Can be obtained by bonding. In this case, at least the extraction electrode portions 23a of the positive electrode and / or the negative electrode are not adhered.

That is, the electrodes 24 and 25 have lead-out portions 24a and 25a that are attached to external lead-out terminals (lead-out electrodes) or partially protrude from the outer periphery of the separator so that the electrodes 24 and 25 themselves constitute the external lead-out terminals. Have.

The separator 23 is adhered at its peripheral portion, that is, at a portion which does not overlap with the electrodes 24 and 25 in a plan view when laminated, and forms an adhesive portion 23b.

Adhesion is performed by the above-mentioned method, and can be formed by the following two methods when forming a laminate.

(1) The electrode-separator composite and the electrode to be paired are laminated, and the side end (ear end) thereof is re-bonded. (2) The electrode-separator composite and the electrode to be paired are laminated, and the heat-shrinkable film is arranged so as to be wound around the outer peripheral portion of the obtained laminated body, particularly the side end portion (ear end portion) thereof. Finally, it adheres to the side end (ear end).

The term "adhesion" used in the present invention means to physically bond the peripheral portions or the edge portions of the separator, or the side portions of the laminate and the heat-sealing film wound in the laminate, to each other.
To fix. Usually, the adhesion takes the form of heat fusion, but when forming a laminate, an optimum adhesion method may be used depending on the material and shape of the separator. For example, an adhesive or a fixing material made of a resin material may be used.

The conditions for heat-sealing the separator depend on the material of the separator used, but usually the heating temperature is preferably about 150 to 350 ° C. The heating time is preferably 0.5 to 5 seconds, particularly preferably 1 to 2 seconds. Further, the pressure when pressurizing is preferably about 7 to ²⁰ kg / cm ² .

As an adhesive region for integrating the laminated body, at least two peripheral portions may be adhered to each other, but the entire edge portion may be adhered.

The laminate obtained by the above methods (1) and (2) is put in an outer package such as an aluminum laminate film to prepare an electrochemical device. In carrying out the present invention, a predetermined part of the fusion-bonded portion may be unfused. By doing so, it has the effect of promoting the permeation of the electrolytic solution into the electrode and preventing the formation of wrinkles. For fusion-bonding the separator, a method such as combined use of heating and pressure bonding is suitable. The fused portion may be bent or unnecessary portions may be cut.

The separator sheet forming the separator has a constituent material of one or more kinds of polyolefins such as polyethylene and polypropylene (in the case of two or more kinds, there is a laminated product of two or more layers),
Examples thereof include polyesters such as polyethylene terephthalate, thermoplastic fluororesins such as ethylene-tetrafluoroethylene copolymer, and celluloses. The form of the sheet is such that the air permeability measured by the method specified in JIS-P8117 is about 5 to 2000 seconds / 100 cc, and the thickness is 5 to 100.
Examples include microporous film of about μm, woven fabric, and non-woven fabric.

In the present invention, it is desirable to use a so-called shutdown separator as the separator. By using the shutdown separator, as the temperature inside the electrochemical device rises, the fine pores of the separator are closed, conduction of ions is suppressed, current is suppressed, and thermal runaway can be prevented. Examples of such a shutdown separator include low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and high-density polyethylene (HDP) described in Japanese Patent No. 2642206.
E) A separator made of a synthetic resin film having at least one kind of fine pores, containing 1% by weight or more of ultrahigh molecular weight polyethylene having a weight average molecular weight of 7 × 10 5 or more described in JP-A-2520316, Made of a microporous membrane composed of polyethylene composition with an average molecular weight / number average molecular weight of 10 to 300, thickness of 0.1 to 25 μm, porosity of 40
A method for producing a lithium battery separator having an average through-hole diameter of 0.001 to 0.1 μm and a breaking strength of 10 mm width of 0.5 kg or more, wherein the polyethylene composition is an aliphatic hydrocarbon or a cyclic hydrocarbon. Alternatively, the solution is heated and dissolved in a non-volatile solvent composed of a mineral oil fraction to form a uniform solution, and the solution is extruded through a die to form a gel-like sheet. After removing the non-volatile solvent, the solution is stretched at least uniaxially by a factor of 2 or more. Examples thereof include a lithium battery separator and the like.

Further, JP-A-9-219184, JP-A-2000-223107, and JP-A-2000-10.
The separator described in Japanese Patent No. 0408 can also be used.

Instead of the separator, a gel type polymer may be used as the electrolyte. For example, (1) polyalkylene oxide such as polyethylene oxide and polypropylene oxide, (2) copolymer of ethylene oxide and acrylate, (3) copolymer of ethylene oxide and glycyl ether, (4) ethylene oxide and glycyl ether. Copolymer with allyl glycyl ether,
(5) Polyacrylate (6) Polyacrylonitrile (7) Polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-trifluorotrifluoroethylene copolymer, vinylidene fluoride-hexafluoropropylene fluorine Examples of the rubber include vinylidene fluoride, and fluoropolymers such as tetrafluoroethylene-hexafluoropropylene fluororubber.

The gel polymer may be mixed with the electrolytic solution or may be applied to the separator or the electrode. Furthermore, the gel polymer may be cross-linked by adding an initiator by ultraviolet rays, EB, heating or the like.

As the heat-shrinkable film for wrapping the laminated body, polyethylene, polypropylene and the like exemplified in the above separator can be used. In addition, PET
Films, PEN films, aramid films and the like can also be used.

The thickness of the heat-shrinkable film is not particularly limited, but is usually about 5 to 50 μm.
The shrinking temperature of the heat shrinkable film is preferably 9
It is about 0 to 200 ° C.

The electrochemical device of the present invention has, for example, a structure in which positive and negative electrodes and separators made of metal foil such as aluminum foil or copper foil are alternately laminated. External electrodes (lead-out terminals) are connected to the positive and negative electrodes, respectively. The external electrode is aluminum,
It is composed of a metal foil such as copper, nickel, and stainless steel.

The electrochemical device used in the electrochemical device of the present invention is not limited to a battery such as a lithium secondary battery, and a capacitor having a similar structure to this can be used.

The electrochemical device of the present invention can be used as the following lithium secondary battery and electric double layer capacitor.

<Lithium Secondary Battery> The structure of the lithium secondary battery is not particularly limited, but is usually composed of a positive electrode, a negative electrode and a separator, and is applied to a laminated battery, a cylindrical battery or the like.

The electrode to be combined with the polymer solid electrolyte may be appropriately selected from those known as electrodes for lithium secondary batteries and used, preferably an electrode active material, a gel electrolyte and, if necessary, a conductive auxiliary agent. Is used.

A negative electrode active material such as a carbon material, lithium metal, a lithium alloy or an oxide material is used for the negative electrode, and an oxide or a carbon material capable of intercalating / deintercalating lithium ions is used for the positive electrode. It is preferable to use a positive electrode active material such as By using such an electrode, a lithium secondary battery having good characteristics can be obtained.

The carbon material used as the electrode active material may be appropriately selected from, for example, mesocarbon microbeads (MCMB), natural or artificial graphite, resin-fired carbon material, carbon black, carbon fiber and the like. These are used as powder. Of these, graphite is preferable, and its average particle diameter is preferably 1 to 30 μm, and particularly preferably 5 to 25 μm. If the average particle size is too small, the charge / discharge cycle life tends to be short, and the capacity variation (individual difference) tends to increase. If the average particle size is too large, the variation in capacity becomes extremely large and the average capacity becomes small. When the average particle diameter is large, the variation in capacity is considered to be due to the variation in the contact between graphite and the current collector and the contact between graphite.

Lithium ion is an intercalating day
Intercalatable oxides include lithium
Complex oxides are preferred, for example LiCoO 2.₂, LiM
n₂O _Four, LiNiO₂, LiV₂O_FourAnd so on.
The average particle size of these oxide powders is about 1-40 μm
Is preferred.

A conductive auxiliary agent is added to the electrode if necessary. Examples of the conductive aid include graphite, carbon black, carbon fibers, metals such as nickel, aluminum, copper, silver and the like, and graphite and carbon black are particularly preferable.

The electrode composition of the positive electrode is preferably in the range of active material: conductive assistant: binder = 80 to 94: 2 to 8: 2 to 18 in weight ratio, and in the negative electrode, the active material: conductive assistant is in weight ratio. Agent: Binder = The range of 70 to 97:00 to 25: 3 to 10 is preferable.

As the binder, a thermoplastic elastomer resin such as a fluororesin, a polyolefin resin, a styrene resin, an acrylic resin, or a rubber resin such as fluororubber can be used. Specific examples thereof include polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polyacrylonitrile, nitrile rubber, polybutadiene, butylene rubber, polystyrene, styrene-butadiene rubber, polysulfide rubber, nitrocellulose, cyanoethyl cellulose, carboxymethyl cellulose and the like.

To manufacture the electrode, first, an active material and, if necessary, a conductive auxiliary agent are dispersed in a binder solution to prepare a coating solution.

Then, this electrode coating liquid is applied to the current collector. The means for applying is not particularly limited and may be appropriately determined depending on the material and shape of the current collector. Generally, a metal mask printing method, an electrostatic coating method, a dip coating method, a spray coating method, a roll coating method, a doctor blade method, a gravure coating method, a screen printing method and the like are used.
Then, if necessary, rolling treatment is performed by a flat plate press, a calendar roll, or the like.

The current collector may be appropriately selected from ordinary current collectors depending on the shape of the device used by the battery, the method of arranging the current collector in the case, and the like. Generally, aluminum or the like is used for the positive electrode and copper, nickel or the like is used for the negative electrode.
A metal foil, a metal mesh, or the like is usually used as the current collector. Although the metal mesh has a smaller contact resistance with the electrode than the metal foil, the metal foil can also obtain a sufficiently small contact resistance.

Then, the solvent is evaporated to produce an electrode. The coating thickness is preferably about 50 to 400 μm.

Such a positive electrode, a separator and a negative electrode are laminated in this order and pressure-bonded to obtain a battery body.

The electrolytic solution with which the separator is impregnated generally comprises an electrolyte salt and a solvent. Examples of the electrolyte salt include L
iBF ₄ , LiPF ₆ , LiAsF ₆ , LiSO ₃ CF
Lithium salts such as ₃ , LiClO ₄ , and LiN (SO ₂ CF ₃ ) ₂ can be applied.

The solvent of the electrolytic solution is not particularly limited as long as it has a good compatibility with the above-mentioned solid polymer electrolyte and electrolyte salt, but polar organic compounds which do not decompose even in a high operating voltage in a lithium battery or the like. Solvents, for example, ethylene carbonate (abbreviated as EC), propylene carbonate (abbreviated as PC), butylene carbonate, dimethyl carbonate (abbreviated as DMC), carbonates such as diethyl carbonate, ethylmethyl carbonate, tetrahydrofuran (THF), 2-methyltetrahydrofuran, etc. Cyclic ethers, cyclic ethers such as 1,3-dioxolane and 4-methyldioxolane, lactones such as γ-butyrolactone and sulfolane are preferably used. 3-Methylsulfolane, dimethoxyethane, diethoxyethane, ethoxymethoxyethane, ethyl diglyme and the like may be used.

The concentration of the electrolyte salt when considering that the solvent and the electrolyte salt constitute the electrolyte solution is preferably 0.3 to 5 mol.
l / l. Usually, the highest ionic conductivity is shown around 0.8 to 1.5 mol / l.

<Electric Double Layer Capacitor> The structure of the electric double layer capacitor used in the present invention is not particularly limited, but usually, a pair of polarizable electrodes are arranged via a separator, and the polarizable electrode and the peripheral portion of the separator are arranged. An insulative gasket is preferably arranged in the. Such an electric double layer capacitor may be of what is called a paper type, a laminated type or the like.

As the polarizable electrode, activated carbon, activated carbon fiber or the like is used as a conductive active material, and a fluororesin, fluororubber or the like is added as a binder thereto. And it is preferable to use what formed this mixture in the sheet-like electrode. The amount of the binder is about 5 to 15% by mass. A gel electrolyte may be used as the binder.

The collector used for the polarizable electrode is platinum,
It may be conductive rubber such as conductive butyl rubber, may be formed by thermal spraying of a metal such as aluminum or nickel, and a metal mesh may be attached to one surface of the electrode layer.

In the electric double layer capacitor, the polarizable electrode and the separator as described above are combined. The separator is the same as that shown in the above lithium secondary battery.

The separator may be, for example, PEO.
(Polyethylene oxide) -based, PAN (polyacrylonitrile) -based, PVDF (polyvinylidene fluoride) -based polymer microporous membranes can be used.

As the electrolyte salt, (C ₂ H ₅ ) ₄ NB can be used.
F ₄ , (C ₂ H ₅ ) ₃ CH ₃ NBF ₄ , (C ₂ H ₅ ) ₄ PB
F _4, and the like.

The non-aqueous solvent used in the electrolytic solution may be any of various known ones. Electrochemically stable non-aqueous solvents such as propylene carbonate, ethylene carbonate and γ-
Butyrolactone, acetonitrile, dimethylformamide, 1,2-dimethoxyethane, sulfolane alone or a mixed solvent is preferable.

The concentration of the electrolyte in such a non-aqueous solvent electrolyte solution may be 0.1 to 3 mol / l.

When a microporous polymer film is dipped in such an electrolytic solution, the polymer film absorbs the electrolytic solution and gels to become a polymer solid electrolyte.

When the composition of the solid polymer electrolyte is represented by the copolymer / electrolyte solution, the ratio of the electrolyte solution is preferably 40 to 90% by mass from the viewpoint of membrane strength and ionic conductivity.

As the insulating gasket, an insulator such as polypropylene or butyl rubber may be used.

The outer package is composed of a laminate film in which a polyolefin resin layer such as polypropylene or polyethylene as a heat-adhesive resin layer or a heat-resistant polyester resin layer is laminated on both surfaces of a metal layer such as aluminum. . The exterior body is formed in a bag shape in which one side is opened by previously heat-bonding two laminated films to each other by thermally adhering the thermoadhesive resin layers on the end faces of the three sides. Alternatively, a single laminated film may be folded back and the end faces of both sides may be heat-bonded to form a seal portion to form a bag shape.

The laminate film has a laminated structure of a thermoadhesive resin layer / polyester resin layer / metal foil / polyester resin layer from the interior side in order to secure insulation between the metal foil forming the laminate film and the lead-out terminal. It is preferable to use a laminated film. By using such a laminated film, the polyester resin layer having a high melting point remains without being melted at the time of heat bonding, so that a separation distance between the lead-out terminal and the metal foil of the outer package can be secured and insulation can be secured. Therefore, the thickness of the polyester resin layer of the laminated film is preferably about 5 to 100 μm.

[0087]

EXAMPLES The present invention will be described in more detail below with reference to examples and comparative examples. Example 1 The apparatus shown in FIG. 1 was used. This apparatus comprises a pressurizing portion for adhering a positive electrode or a negative electrode to a separator made of a polymer, and a bag-like melt adhesive (heater).

Preparation of electrodes Positive electrode A. LiCoO ₂ [Seimi Chemical Co., Ltd.], B.I. Conductive carbon type acetylene black
[Electrochemical Co., Ltd.] C.I. PVdF resin type KY-761A [Elf Attoina Co., Ltd.] The composition ratio was A / B / C = 92/2/6, and it was made into a paint by a conventional method, and applied on a 20 μm aluminum foil to 100 μm. After coating, pressure rolling was performed.

Anode A. Spherical graphite MCMB [Osaka Gas Co., Ltd.] B. PVdF resin type KY-761A [Elf Attoina Co., Ltd.] Composition ratio A / B = 91/7 was made into a paint by a conventional method, and 20 μm
100 μm was applied to a copper foil of m 2. After coating, pressure rolling was performed.

Preparation of bag-like electrode This time, the negative electrode was formed into a bag shape. Using electrodes of size 65 x 30 mm (excluding terminals), a polymer separator (Tonen E16M MS) is cut into a predetermined size, and a negative electrode is placed on the separator, and further cut into a predetermined size. A cut separator (Tonen E16MMS) was put on the bag, and a bag-shaped electrode was prepared by the following procedure using the apparatus shown in FIG. In addition,
The separator is not limited to E16MMS,
A commercially available product can be appropriately selected and used.

(1) First, the polymer separator 11 was cut into a predetermined size and conveyed and supplied to the fixed suction cup unit 8 by a uniaxial robot with a suction cup (not shown). (2) Next, one negative electrode 12 was adsorbed by a uniaxial robot with a suction cup (not shown) and supplied to the electrode alignment XY-θ table 7. (3) Electrode Positioning XY-θ Table 7 is driven by a pulse motor, a servomotor, or the like, and the electrode position is confirmed by the electrode positioning camera 6 having an image processing function, and the XY-θ table is displayed. The electrode position was corrected in the direction. (4) The negative electrode 12 for which the alignment was completed was supplied from the table 7 onto the polymer separator 11 on the fixed suction cup unit 8 by a uniaxial robot with a suction cup. (5) Further, the polymer separator 11 was supplied onto the negative electrode 12 of the fixed suction cup unit 8 by the uniaxial robot with suction cup. With this, the negative electrode 12 is sandwiched between the two separators. (6) Next, the seal heater unit 5 was lowered by the pressurizing / lifting air cylinder 3, and pressure was applied on the electrode 12 sandwiched between the polymer separators 11. The cooling plate 54 in the seal heater unit 5 is constantly pressurized by the cooling plate elevating air cylinder in the seal heater unit 5. Therefore, the cooling plate 54 is retracted into the seal heater unit 5 by the thickness of the electrode due to the pressure of the heater pressure cylinder, and the polymer separator 11 and the electrode 12 are pressure bonded. (7) Next, a pulsed current was supplied to the heater 51 with an impulse sealer to melt and bond the separators 11 to each other. (8) When the bonding is completed, the air cylinder for raising and lowering the heater unit is raised. At this time, the cooling plate 54
The bag-shaped electrode was pushed down by the stroke of, and the welded polymer separator was peeled off from the heater.

Table 1 below shows the fusion width and the size of the heating element.
As shown in, evaluation was performed by changing the fusion width. Further, the distance between the heating element (heater) and the electrode (outer dimension of the heating element-outer dimension of the electrode) was variously changed as shown in Table 2 and evaluated.

[0093]

[Table 1]

[0094]

[Table 2]

Battery-making and battery evaluation conditions Using the bag-shaped electrodes of A1 to A5 and B1 to B5, a pair of electrodes (anode) was further laminated to form a laminated body, and this laminated body was lead-bonded to the exterior. It was inserted into the body (aluminum laminated film).

Next, EC / DEC = 3/7 1MLiP
An electrolyte solution of F ₆ was poured, sealed, precharged and aged to prepare a laminated non-aqueous electrolyte secondary battery.
The capacity of the battery obtained at this time was 800 mAh. An experiment was conducted below by combining the bag-shaped electrodes prototyped in the preliminary experiment, and used as comparative examples and examples. For the battery evaluation, a charging / discharging device manufactured by Kikusui Electronics Co., Ltd. was used, and the cycle life was evaluated by an ordinary method. In the cycle test, charging / discharging was performed at a current equivalent to 1C. In addition, about A6 and B6, since the separator broke, it could not be made into a battery.

[0097]

[Table 3]

Battery Evaluation Results From Table 3, it can be seen that the cycle life is improved by using the bag-shaped electrodes of the examples of the present invention.

[0099]

As described above, according to the present invention, even when the temperature at which heat shrinkage is reached, the shrinkage does not exceed a certain level, there is no short circuit between the positive and negative electrode sheets, and the ionic conductivity of the separator is adversely affected. Therefore, it is possible to provide a method and a manufacturing apparatus for efficiently manufacturing a high-performance electrochemical device which is excellent in safety and does not lead to a hard short circuit.

[Brief description of drawings]

FIG. 1 is a schematic perspective view showing an apparatus for manufacturing an electrochemical device of the present invention.

FIG. 2 is a schematic perspective view showing a configuration example of a heater unit.

FIG. 3 is a plan view showing a bag-shaped separator of the present invention.

FIG. 4 is a cross-sectional view showing a constitutional example of an electrochemical device laminate of the present invention.

[Explanation of symbols]

1 Melt bonding unit 2 body 3 Pressurized lifting air cylinder 3 4 Cooling plate lifting cylinder 5 Seal heater unit 5 6-electrode alignment camera 7 XY-θ table 8 Fixed suction cup unit 8

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Akira Saito             1-13-1, Nihonbashi, Chuo-ku, Tokyo             -In DC Inc. (72) Inventor Maro Tai             1-13-1, Nihonbashi, Chuo-ku, Tokyo             -In DC Inc. F term (reference) 5E082 AB09 BC36 LL21 MM24 PP09                 5H021 AA06 BB01 BB11 BB19 CC04                       CC13 CC18 HH03                 5H029 AJ01 AJ12 AK03 AK06 AL02                       AL06 AL07 AL08 AL12 AM02                       AM03 AM04 AM05 AM07 AM16                       BJ04 BJ12 CJ02 DJ04 EJ04                       EJ12 HJ04

Claims (8)

[Claims] 1. When manufacturing an electrochemical device having a laminate in which a positive electrode and a negative electrode are laminated via a separator, at least the positive electrode and / or the negative electrode is sandwiched between separators, and a part of the peripheral portion of the separator is partially joined. A method for producing an electrochemical device, which comprises melt-adhering to form a bag shape, in which a width of an adhesive portion around a separator is set to 0.3 mm or less. 2. A method of manufacturing an electrochemical device, wherein an adhesive portion in the peripheral portion of the separator exists within 1 mm from the outer peripheral portion of the electrode. 3. The method for manufacturing an electrochemical device according to claim 1, wherein the melt bonding is performed by contacting a heat radiating member or a cooling member other than the melt bonded portion to carry out the melt bonding. 4. The method for manufacturing an electrochemical device according to claim 1, wherein the fusion bonding is performed by pressing a heating element having a width of 0.3 mm or less. 5. An electrochemical device having a laminate in which a positive electrode and a negative electrode are laminated via a separator, wherein the positive electrode and / or the negative electrode is housed in a bag-shaped separator, and a peripheral portion of the separator is provided. An electrochemical device in which the width of the bonded portion is 0.3 mm or less. 6. A manufacturing apparatus for manufacturing an electrochemical device having a laminated body in which a positive electrode and a negative electrode are laminated with a separator interposed therebetween, which has a heat-generating member for performing fusion bonding for processing the separator into a bag shape. The heat generating member is arranged on the outer periphery of the positive electrode and / or the negative electrode sandwiched between the separators so that the part corresponding to the positive electrode and / or the negative electrode is hollow, and the width of the part contacting the separator is 0.3 mm or less. Electrochemical device manufacturing equipment. 7. The apparatus for manufacturing an electrochemical device according to claim 6, wherein the heat generating member is arranged within 1 mm from the outer peripheral portion of the positive electrode and / or the negative electrode sandwiched by the separators. 8. The apparatus for manufacturing an electrochemical device according to claim 6, further comprising a heat dissipation member or a cooling member that is in contact with other than the melt-bonded portion.