JP2001068155A - Stacked polymer electrolyte battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stacked polymer electrolyte battery with high safety, capable of preventing emitting smoke.ignition even when the battery is short- circuited being nailed or crushed. SOLUTION: This polymer electrolyte battery is assembled by sealing a stacked electrode group formed by stacking positive electrodes 1 having a positive electrode mix layer 1b formed on at least one side of a positive electrode current collector 1a and negative electrodes 2 having a negative electrode mix layer 2b formed on at least one side of a negative electrode current collector 2a so as to interpose a polymer electrolyte layer between a set of electrodes into an outer case 4 containing a metal foil. The thickness of the electrode current collector of at least one outermost electrode of the stacked electrode group is made 30 μm or more, the electrode mix layer is not formed on the outside of this electrode current collector, a lead part 2c of the electrode having the same polarity and this electrode current collector are connected, and the thickness of the metal foil of the outer case is made 30 μm or more, and an electrode terminal having the other polarity and the metal foil of the outer case are connected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stacked polymer electrolyte battery, and more particularly, to a stacked polymer electrolyte battery suitable for use as a power source for portable electronic devices, electric vehicles, road leveling, and the like.

[0002]

2. Description of the Related Art In a polymer electrolyte battery, the electrodes and the electrolyte can be made into a sheet shape, whereby A4
It is possible to manufacture a large-sized and thin battery such as a plate and a B5 plate, and it is possible to apply the battery to various thin products, thereby widening the range of use of the battery. In particular, batteries using polymer electrolytes have excellent safety and storage properties including leak resistance, and are thin and flexible.
It has the unique features of batteries that can be designed to match the shape of the device.

[0003] This polymer electrolyte battery usually uses a laminate film in which an aluminum foil is used as a core material and a heat-fusible resin film serving as an adhesive layer is disposed on the inner surface side as an outer package. Then, a thin sheet-type battery is completed by covering the laminated electrode group, in which the sheet-like electrode and the sheet-like polymer electrolyte layer are laminated, with an outer package.

In this laminated polymer electrolyte battery, when the number of laminated electrodes is small and the electric capacity or electric capacity density is low, that is, when the inherent energy is low, the above-mentioned excellent safety is secured. However, when the number of stacked electrodes increases and the electric capacity and electric capacity density increase, the safety is not sufficient.If the electrodes are short-circuited due to nail penetration or crushing, a large current flows, heat is generated, and smoke is generated. It has been found that fire, rupture and other accidents may occur.

[0005] The above-mentioned problems can be solved by making a large current flowing at the time of short circuit flow out of the stacked electrode group, rapidly dissipating heat, and reducing heat storage. However, in the laminated electrode group of the laminated polymer electrolyte battery, a positive electrode and a negative electrode face each other via a polymer electrolyte layer having poor heat conductivity, and a plurality of these layers are stacked, and a heat-fusible resin film having poor heat conductivity has an inner surface. It is considered that heat is stored inside the battery due to heat generation such as a short circuit due to the exterior body disposed on the side, and the internal temperature rises greatly, leading to accidents such as smoking, ignition and rupture.

[0006]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the prior art, and devises the thickness of the current collector of the electrode, the thickness of the metal foil of the outer package, and the battery structure. An object of the present invention is to provide a laminated polymer electrolyte battery having high safety by enhancing stiffness even when the capacity is increased, and having high safety.

[0007]

According to the present invention, there is provided a positive electrode having a positive electrode mixture layer formed on at least one surface of a positive electrode current collector, and a negative electrode mixture layer formed on at least one surface of a negative electrode current collector. A negative electrode formed, a laminated electrode group laminated with a polymer electrolyte layer interposed therebetween, a laminated polymer electrolyte battery packaged with a package containing a metal foil, at least of the laminated electrode group The thickness of the electrode current collector of one outermost layer electrode is 30 μm or more, and no electrode mixture layer is formed on the outer surface side, and the electrode current collector is connected to the lead of an electrode of the same polarity. And the thickness of the metal foil of the exterior body is 3
The above-mentioned problem is solved by connecting the electrode terminal of the other polarity to the metal foil of the exterior body to have a thickness of 0 μm or more.

That is, as described above, the thickness of the electrode current collector of at least one outermost layer electrode of the stacked electrode group is set to 30.
μm, without forming an electrode mixture layer on the outer surface side, connecting the electrode current collector and the lead of an electrode of the same polarity, and making the thickness of the metal foil in the exterior body 30 μm or more, By connecting the electrode terminal of the other polarity and the metal foil in the outer package, an external short circuit first occurs due to a short circuit inside the stacked electrode group due to nail penetration or crushing, thereby lowering the battery voltage,
Heat generation due to a chemical reaction can be reduced. Moreover, by utilizing the fact that the metal foil in the outer package is provided outside the laminated electrode group and that the electrode current collector is disposed on the outermost layer of the laminated electrode group, Heat can be smoothly released by the body and the metal foil. Therefore, by adopting the above-described configuration, safety can be improved even when the capacity is increased, and a stacked polymer electrolyte battery with high safety can be provided.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, the outermost electrode of the laminated electrode group may be either a positive electrode or a negative electrode. However, from the viewpoint of forming a reliable short circuit, a negative electrode having a larger area is preferred. It is preferable (normally, in a laminated polymer battery, the size of the negative electrode is made larger than the size of the positive electrode in order to prevent lithium dendrite generated during overcharge). And the thickness of the current collector of the electrode needs to be 30 μm or more. The thickness of the current collector is 30 μm
If it is thinner, for example, a large current flowing due to a short circuit caused by a nail penetration causes the contact portion to locally generate heat and melt to form an electric short circuit, thereby eliminating the short circuit and eliminating its use. Otherwise, the heat dissipation promoting action, which is another function, is reduced, the heat dissipation is delayed, and the heat storage is increased, which may lead to smoke or ignition. And the material of the electrode current collector is not particularly limited, for example,
Copper, nickel, stainless steel and the like are preferred.

[0010] The same applies to the metal foil in the outer package connected to the electrode terminal of the other electrode (usually a positive electrode in many cases), and the thickness must be 30 µm or more, and the thickness is 30 µm or more.
If the thickness is thinner, the short circuit is not reliably formed and the heat dissipation is not sufficient for the same reason as in the case of the outermost electrode current collector. Since the metal foil in the outer package does not come into contact with the electrolyte, its material is not particularly limited, and various materials can be adopted. For example, an aluminum foil having excellent spreadability is particularly preferable.

As described above, the outermost electrode current collector of the laminated electrode group and the metal foil in the outer package need to have a thickness of 30 μm or more. The thickness is preferably 200 μm or less, since the thickness may be lowered to lose the characteristics of the laminated polymer electrolyte battery.

The electrode current collector of the outermost layer electrode of the above-mentioned laminated electrode group and the metal foil of the exterior body do not necessarily have to be non-porous, but may be made of a porous metal such as a punching metal, a net-like or lath-like metal. It may be textured. Also,
In the present invention, connecting the electrode current collector of the outermost layer electrode of the laminated electrode group and the lead portion of the electrode of the same polarity or connecting the electrode terminal of the other polarity to the metal foil in the exterior body Means directly connecting the electrode current collector of the outermost layer electrode of the stacked electrode group and the lead of the electrode of the same polarity, or connecting the electrode terminal of the other polarity to the external terminal. It is not necessary to connect directly to the metal foil in the body,
A lead body or the like may be interposed between them, or the above-mentioned electrode current collector may be provided with a lead portion like other components, and may be connected to a lead portion of an electrode having the same polarity as the other. Good.

In the present invention, the positive electrode, the negative electrode, and the polymer electrolyte layer may be formed separately from each other when preparing the laminated electrode group. However, at least one of the positive electrode and the negative electrode is previously formed with the polymer electrolyte layer. It is preferable that the electrodes and the polymer electrolyte layer be integrated so as to surround the electrodes. As a form in this case, for example, after surrounding the electrode in a bag-shaped porous sheet serving as a support of the polymer electrolyte layer, the entire electrolyte solution containing a gelling component which is a precursor of the polymer electrolyte, Impregnated and gelled to produce an integral body of polymer electrolyte-containing electrode and support, or a polymer electrolyte-containing electrode, a strip-shaped polymer electrolyte sheet with a porous sheet support built-in For example, a case where the electrode and the polymer electrolyte layer are integrated with each other. Furthermore, when the latter electrode is sandwiched between strip-shaped polymer electrolyte sheets to surround the electrodes with a polymer electrolyte layer, one strip-shaped polymer electrolyte sheet is folded at substantially the center thereof and is interposed between the polymer electrolyte sheets. There are a case where the electrode is surrounded by the polymer electrolyte layer by sandwiching the electrode, and a case where the electrode is surrounded by the polymer electrolyte layer by sandwiching the electrode between two strip-shaped polymer electrolyte sheets.

In the above case, for example, a nonwoven fabric or a microporous film is used as the porous sheet serving as a support for the polymer electrolyte. As the above nonwoven fabric,
For example, nonwoven fabrics such as polypropylene, polyethylene, polyethylene terephthalate, and polybutylene terephthalate can be used. Examples of the microporous film include microporous films of polypropylene, polyethylene, and ethylene-propylene copolymer.

Since the nonwoven fabric has a high porosity and is easily impregnated with an electrolytic solution containing a gelling component, it can be suitably used. Therefore, the case where the nonwoven fabric is used as a support will be described in detail. , Basis weight is 12g
/ M ² and a very thin nonwoven fabric having a thickness of 30 μm can be used.

Such a nonwoven fabric has a low mechanical strength such as tensile strength because of its thinness, and is difficult to handle alone. For example, the nonwoven fabric is formed into a bag and the electrodes are accommodated in the bag-shaped nonwoven fabric. By surrounding and integrating the nonwoven fabric and the electrode, the strength of the electrode can compensate for the insufficient strength of the nonwoven fabric. Also, without forming a bag shape, the strip-shaped non-woven fabric is folded almost at the center, and the electrode is sandwiched between the non-woven fabrics to surround the electrode with the non-woven fabric and integrate the electrode and the non-woven fabric. By overlapping the strip-shaped non-woven fabric, sealing one end of the non-woven fabric, sandwiching the electrode between the non-woven fabrics, surrounding the electrode with a support, and integrating the electrode and the non-woven fabric, the strength of the non-woven fabric also increases the strength of the electrode. Insufficient strength can be compensated, and workability during battery assembly can be improved, internal resistance can be reduced, and load characteristics can be improved. The case where a microporous film is used as the support is the same as the case of the nonwoven fabric.

As described above, the electrode is surrounded by a support made of a porous sheet such as a nonwoven fabric, and the electrode and the support are integrated, and the electrode is impregnated with an electrolytic solution containing a gelling component to be gelled. Thereby, the adhesion between the electrodes and the polymer electrolyte layer is better than when the electrodes and the polymer electrolyte sheet are individually gelled to form the electrode and the polymer electrolyte sheet and then laminated, and bubbles, foreign substances, and the like can be interposed between the layers. Since the amount is small, the ion transfer at the interface becomes smooth, and the reactivity between the positive electrode and the negative electrode is improved. In addition, by surrounding one of the positive electrode and the negative electrode with a support, it can also serve as a physical separator.

Then, one of the positive electrode and the negative electrode may be surrounded by the polymer electrolyte layer to integrate the electrode and the polymer electrolyte layer. At this time, the positive electrode is surrounded by the polymer electrolyte layer. When the positive electrode and the polymer electrolyte layer are integrated, the battery capacity can be larger than when the negative electrode is surrounded by the polymer electrolyte layer. That is,
Generally, it is common practice to make the negative electrode larger than the positive electrode in order to prevent dendrite generation and ensure safety.If the positive electrode is surrounded by the polymer electrolyte layer, then the negative electrode is surrounded by the polymer electrolyte layer rather than the polymer electrolyte layer. Can be reduced, and as a result, the battery capacity can be increased. Also, when the negative electrode is surrounded by the polymer electrolyte layer and the negative electrode and the polymer electrolyte layer are integrated, the interface state between the negative electrode and the polymer electrolyte layer can be made uniform. It is effective in improving the properties.

Furthermore, if both the positive electrode and the negative electrode are surrounded by the polymer electrolyte layer, the thickness of the polymer electrolyte layer is increased, but both the electrodes are integrated with the polymer electrolyte layer. Also, the polarization can be reduced, and the reaction at the time of charging / discharging can proceed smoothly, so that the load characteristics can be greatly improved.

In the present invention, the integration of the electrode and the polymer electrolyte layer means that the electrode and the polymer electrolyte layer are brought into close contact with each other without bubbles or foreign matter between the electrode and the polymer electrolyte layer. It does not mean that it is inseparably bonded.

When the support made of a porous sheet such as the above nonwoven fabric is formed into a bag shape, if the bag shape is described as, for example, a rectangular shape, one side is usually open and the other three sides are sealed. However, the sealing is not always required to be continuously performed, and the sealing may be discontinuously performed.

When accommodating the electrode in the bag-like support, it is not required that the support is made into a bag-like shape in advance, and the electrode is made into a strip-like support (for example, the length is twice the length of the electrode). As described above, a strip-shaped support having a width larger than the width of the electrode is placed on one side from the substantially central portion in the length direction, and the other width is folded back (that is, the electrode is folded back substantially at the center portion). It is sufficient that the electrodes are housed in a bag-like support by sealing the two sides in the width direction continuously or discontinuously.

In the case where two supports are overlapped and one end thereof is sealed and an electrode is sandwiched between the two supports, it is not necessary to seal the electrodes in advance. For example, it is placed on a strip-shaped support whose length is longer than the length of the electrode and whose width is wider than the width of the electrode), another strip-shaped support is placed thereon, and the support At one end, continuously or discontinuously,
What is necessary is just to make the electrode sandwiched between the support bodies.

Electrolyte for forming polymer electrolyte layer
As, for example, dimethyl carbonate, diethyl carbonate
-Carbonate, methyl ethyl carbonate, propionic acid
Methyl, ethylene carbonate, propylene carbonate
G, butylene carbonate, γ-butyrolactone, ethyl
Len glycol sulfite, 1,2-dimethoxy eta
1,3-dioxolan, tetrahydrofuran, 2-
Methyl-tetrahydrofuran, diethyl ether, etc.
In an organic solvent, for example, LiClO_Four, LiPF ₆, Li
BF_Four, LiAsF₆, LiCF_ThreeSO_Three, LiC_FourF
₉SO_Three, LiCF_ThreeCO_Two, Li_TwoC_TwoF_Four(S
O_Three)_Two, LiN (CF_ThreeSO_Two)_Two, LiC (CF_Three
SO_Two)_Three, LiC_nF_{2n + 1}SO_Three(N ≧ 2), Li
N (RfOSO_Two)_Two[Where Rf is fluoroalkyl
Prepared by dissolving inorganic ion salts such as
Is used. This inorganic ion salt in the electrolyte
The concentration is 0.5 to 1.5 mol / l, especially 0.9
~ 1.25 mol / l is preferred.

As the gelling component for converting the electrolytic solution into a polymer electrolyte, for example, polyvinylidene fluoride, polyethylene oxide, polyacrylonitrile,
After dissolving a linear polymer such as a vinylidene fluoride-propylene hexafluoride copolymer in an electrolytic solution by heating and then cooling it to polymerize the electrolytic solution, or polymerizing with actinic rays Examples include a crosslinkable composition containing two or more possible double bonds per molecule and containing a monomer or a prepolymer as a main component.

Examples of the monomer capable of being polymerized by actinic light include monomers having two double bonds per molecule (bifunctional crosslinkable monomers) such as 1,3-butanediol diacrylate and 1,4 -Butanediol diacrylate, 1,6-hexanediol diacrylate, ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol diacrylate, propylene glycol diacrylate, dipropylene glycol diacrylate Acrylate, tripropylene glycol diacrylate, ethoxylated bisphenol A diacrylate, novolak diacrylate, propoxylated neopentyl glycol diacrylate Such as difunctional acrylates and the acrylate and similar difunctional methacrylates such as chromatography bets and the like.

Examples of monomers having three double bonds polymerizable by actinic rays per molecule (trifunctional crosslinking monomers) include, for example, tris (2-hydroxyethyl) isocyanurate triacrylate, trimethylolpropane triacrylate. Trifunctional acrylates such as acrylate, ethoxylated trimethylolpropane triacrylate, pentaerythritol triacrylate, propoxylated trimethylolpropane triacrylate, propoxylated glyceryl triacrylate, caprolactone-modified trimethylolpropane acrylate, and trifunctional methacrylates similar to the above acrylates Is mentioned.

Examples of the monomer having four or more double bonds per molecule capable of being polymerized by actinic light (tetrafunctional or more crosslinkable monomer) include, for example, pentaerythritol tetraacrylate, ditrimethylolpropane tetraacrylate, ethoxylated Examples include tetrafunctional or higher acrylates such as pentaerythritol tetraacrylate, dipentaerythritol hydroxypentaacrylate, dipentaerythritol hexaacrylate, and tetrafunctional or higher methacrylates similar to the above acrylates.

Further, a double bond which can be polymerized by actinic rays
Examples of the prepolymer having at least four, preferably four or more include prepolymers of urethane acrylate, epoxy acrylate, and polyester acrylate, and can be used in place of the above-mentioned monomers.

In the present invention, the monomer or prepolymer having two or more double bonds per molecule capable of being polymerized by actinic light may be used as a main component, for example, for adjusting physical properties such as gel hardness. For this purpose, a monofunctional monomer or the like can be used in combination. Further, a usage such as mixing a bifunctional monomer and a hexafunctional monomer is also possible.

In the present invention, the term "crosslinkable composition comprising a monomer or a prepolymer having two or more double bonds per molecule which can be polymerized by actinic light" as a main component means that the above-mentioned crosslinkable composition is polymerized by actinic light. Monomers or prepolymers containing only possible monomers or prepolymers having two or more double bonds per molecule, and monomers or prepolymers having two or more double bonds per molecule that can be polymerized with actinic rays with monofunctional monomers In the case where a monomer or a prepolymer having two or more double bonds per molecule capable of being polymerized by actinic rays is used in combination with a monofunctional monomer or the like as in the latter case, the crosslinkable composition Of a monomer or a prepolymer having two or more double bonds per molecule which can be polymerized by actinic light, more than 50% by weight, especially 70% by weight. Or more at a wavelength of 550 nm. Also,
The crosslinkable composition does not have to be all crosslinkable as long as the constituents thereof are not crosslinkable, as long as it is entirely crosslinkable.
Other components can be added as needed.

And, if necessary, as a polymerization initiator,
For example, benzoins, benzoin alkyl ethers, benzophenones, benzoylphenylphosphine oxides, acetophenones, thioxanthones, anthraquinones, and the like can be used. Further, alkylamines, aminoesters and the like can be used as a sensitizer of the polymerization initiator.

In the present invention, for example, ultraviolet rays (UV), electron beams (EB), visible rays, far ultraviolet rays, etc. can be used as the active rays.

[0034]

Next, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to only those illustrated in the embodiments.

Example 1 First, the preparation of the positive electrode and the negative electrode used in Example 1 and the preparation of an electrolyte solution containing a gelling component will be described first.

Preparation of positive electrode: LiCoO as positive electrode active material
₂ 80 parts by weight, acetylene black 10 as a conductive additive
The mixture was uniformly mixed with 10 parts by weight of polyvinylidene fluoride as a binder using N-methylpyrrolidone as a solvent to prepare a positive electrode mixture-containing paste. This positive electrode mixture-containing paste is used as a positive electrode current collector with a thickness of 20 μm.
Is applied to both sides of the aluminum foil, dried and then calendered to adjust the thickness of the positive electrode mixture layer so that the total thickness becomes 130 μm.
The positive electrode was manufactured by cutting so as to be 0 mm × 40 mm. However, in producing the above positive electrode, the positive electrode mixture-containing paste was not applied to part of the aluminum foil, leaving an exposed portion of the aluminum foil, and connecting the exposed portion of the aluminum foil to a lead for connection with a positive electrode terminal or the like. Department. FIG. 1 schematically shows a cross-sectional view of this positive electrode. As shown in FIG. 1, the positive electrode 1 is produced by forming a positive electrode mixture layer 1b on both surfaces of a positive electrode current collector 1a, and a lead portion 1c thereof is part of an aluminum foil constituting the positive electrode current collector 1a. It is constituted by exposing the aluminum foil without applying the paste containing the positive electrode mixture to the aluminum foil.

Preparation of negative electrode A: graphite 90 as a negative electrode active material
Parts by weight and 10 parts by weight of polyvinylidene fluoride are uniformly mixed with N-methylpyrrolidone as a solvent to prepare a negative electrode mixture-containing paste, and on both surfaces of a negative electrode current collector made of a copper foil having a thickness of 10 μm. After coating and drying, calendering is performed to adjust the thickness of the negative electrode mixture layer so that the total thickness becomes 130 μm, and the area of the negative electrode mixture layer formation portion is 72 m.
The negative electrode A was prepared by cutting to a size of mx 42 mm.
In the above cutting, the lead portion to be connected to the negative electrode terminal was located at the center position in the width direction of the electrode. In the same manner as in the case of the above-mentioned positive electrode, in producing the negative electrode A, the negative electrode mixture-containing paste was not applied to a part of the copper foil, leaving an exposed portion of the copper foil, and exposing the exposed portion of the copper foil to the negative electrode. It is a lead part for connection with terminals. In the negative electrode A thus produced, the negative electrode mixture layer was formed on both surfaces of the negative electrode current collector,
This is a so-called double-sided coated negative electrode. FIG. 2 schematically shows a cross-sectional view of the negative electrode A. As shown in FIG.
The negative electrode A is produced by forming a negative electrode mixture layer 2b on both surfaces of a negative electrode current collector 2a, and its lead portion 2c is provided with a negative electrode mixture-containing paste on a part of the copper foil constituting the negative electrode current collector 2a. The coating is not applied and the copper foil is exposed. In the drawing, the negative electrode A and a negative electrode B described later are used.
Both are denoted by the same reference numeral 2.

Preparation of Negative Electrode B: The same negative electrode mixture-containing paste as in the case of the above-described negative electrode A was applied to one surface of a negative electrode current collector made of a copper foil having a thickness of 50 μm, dried, and calendered. The thickness of the negative electrode mixture layer was adjusted so that the total thickness became 110 μm, and the area of the negative electrode mixture layer formation portion was 72 mm ×
Negative electrode B was prepared by cutting to 42 mm. Also, in producing the negative electrode B, the negative electrode mixture-containing paste was not applied to part of the copper foil, leaving an exposed portion of the copper foil,
The exposed portion of the copper foil was used as a lead portion for connection with a negative electrode terminal or the like. The negative electrode B thus produced is a so-called single-sided coated negative electrode in which the negative electrode mixture layer is formed only on one side of the negative electrode current collector. FIG. 3 schematically shows a cross-sectional view of the negative electrode B. As shown in FIG. 3, the negative electrode B is manufactured by forming the negative electrode mixture layer 2b on only one surface of the negative electrode current collector 2a.

Preparation of electrolyte solution containing gelling component: volume ratio of propylene carbonate to ethylene carbonate 1: 1
In an electrolyte prepared by dissolving 1.22 mol / l of LiPF _{6 in} a mixed solvent of
4,6-Trimethylbenzoyldiphenylphosphine oxide (trade name: Lucirin TPO, manufactured by BSF Japan Co., Ltd.) was previously added and dissolved at 2% by weight based on the monomer component, and dipentaerythritol hexaacrylate was added thereto. Ten minutes before the start of use, the mixture was added to a concentration of 6% by weight and mixed to prepare an electrolytic solution containing a gelling component. The electrolytic solution containing the gelling component is simply expressed as “gelling component-containing electrolytic solution” as described above.

The positive electrode prepared as described above is wrapped with a nonwoven fabric serving as a support for the polymer electrolyte layer, the positive electrode and the support are integrated, and the whole is impregnated with a gelling component-containing electrolyte to form a gel. Thus, a polymer electrolyte-containing positive electrode unit was obtained. The negative electrode was impregnated with a gelling component-containing electrolyte solution without being wrapped with a nonwoven fabric, and gelled to obtain a polymer electrolyte-containing negative electrode. The details of the manufacturing method are described below.

Preparation of Positive Electrode Unit Containing Polymer Electrolyte:
As a support, a polybutylene terephthalate nonwoven fabric having a thickness of 30 μm and a basis weight of 12 g / m ² [manufactured by NKK, MB1
230 (trade name)], and the length × width is 144 m
It was cut into a strip of mx 42 mm.

Then, the thickness of the cathode is 50 μm and the width is 3 mm
Was adhered from both sides to prevent short circuit and maintain the strength of the terminal. Also, after covering the entire surface of the portion of the lead portion used for connection with the positive electrode terminal with a heat release tape that loses the adhesiveness of the adhesive surface due to heat,
The positive electrode is placed on the left side of the center of the polybutylene terephthalate nonwoven fabric in the longitudinal direction, and the right side is folded back to cover the positive electrode. : Policyr, Fuji Impulse Co., Ltd.]
To form a bag of polybutylene terephthalate nonwoven fabric as a support, and the two were brought into close contact to integrate the positive electrode and the support. The positive electrode unit in which the positive electrode and the support are integrated is immersed in the gelling component-containing electrolyte for 1 minute under reduced pressure to impregnate the positive electrode unit with the gelling component-containing electrolyte, and then put in a polyethylene bag. And sealed. Next,
UV rays were radiated from both sides of the polyethylene bag at an illuminance of 1 W / cm ² for 10 seconds using an UV irradiator manufactured by Fusion UV Systems Japan Co., Ltd. to polymerize the monomer component in the electrolytic solution. The electrolyte was gelled to form a gel polymer electrolyte. The integrated body of the polymer electrolyte layer and the positive electrode is taken out of the bag, the hot peeling tape is peeled off from the bag by blowing hot air of 150 ° C. onto a portion of the lead portion used for connection with the positive electrode terminal, and the polymer electrolyte holding positive electrode unit is removed. I got

Preparation of the polymer electrolyte-containing negative electrode A: A polyimide tape having a thickness of 50 μm and a width of 3 mm was attached to both sides of the negative electrode A prepared as described above so as to extend over the negative electrode mixture layer forming portion and the lead portion. To prevent short circuit and maintain the strength of the terminals. After covering the entire surface of the portion of the lead portion used for connection with the negative electrode terminal with a heat release tape that loses the adhesiveness of the adhesive surface due to heat, the negative electrode A was decompressed into the gelled component-containing electrolytic solution. After immersion for 1 minute in the lower part to impregnate the electrolytic solution containing the gelling component, the resultant was put in a polyethylene bag and sealed. Next, ultraviolet light was applied to both sides of the polyethylene bag at a rate of 1 W using an ultraviolet irradiation device manufactured by Fusion UV Systems Japan Co., Ltd.
Irradiation was performed for 10 seconds at an illuminance of / cm ² to polymerize the monomer components in the electrolytic solution and gel the electrolytic solution to obtain a gel polymer electrolyte. The negative electrode A holding the gelled polymer electrolyte is taken out of the bag, and a hot air of 150 ° C. is blown to a portion of the lead portion used for connection with the negative electrode terminal, thereby peeling off the thermal release tape from the portion, and the polymer electrolyte-containing negative electrode. A was obtained.

Preparation of Polymer Electrolyte-Containing Negative Electrode B: A polyimide tape having a thickness of 50 μm and a width of 3 mm was attached to both sides of the negative electrode B prepared as described above so as to straddle the negative electrode mixture layer forming portion and the lead portion. To prevent short circuit and maintain the strength of the terminals. Further, after covering all surfaces of a portion of the lead portion used for connection with the negative electrode terminal with a heat release tape which loses the adhesiveness of the adhesive surface due to heat, the negative electrode B was decompressed into the gelled component-containing electrolytic solution. After immersion for 1 minute in the lower part to impregnate the electrolytic solution containing the gelling component, the resultant was put in a polyethylene bag and sealed. Next, ultraviolet rays were irradiated at 1 W / c from the outside of the polyethylene bag to the side on which the negative electrode mixture layer forming portion of the negative electrode B was arranged by using an ultraviolet irradiation device manufactured by Fusion UV Systems Japan Co., Ltd.
Irradiation was performed for 10 seconds at an illuminance of m ² to polymerize the monomer components in the electrolyte and gel the electrolyte to form a gel polymer electrolyte. The negative electrode B holding the gel polymer electrolyte is taken out of the bag, and a hot air at 150 ° C. is blown to a portion of the lead portion used for a connection portion with the negative electrode terminal, thereby peeling off the thermal release tape from the portion, and containing the polymer electrolyte. A negative electrode B was obtained.

The five polymer electrolyte holding positive electrode units prepared as described above and the polymer electrolyte holding negative electrode A4
Sheets and two pieces of the polymer electrolyte holding negative electrode B, a polymer electrolyte holding negative electrode B, a polymer electrolyte holding positive electrode unit, a polymer electrolyte holding negative electrode A, a polymer electrolyte holding positive electrode unit, a polymer electrolyte holding negative electrode A, a polymer electrolyte holding positive electrode unit, a polymer electrolyte The holding negative electrode A, the polymer electrolyte holding positive electrode unit, the polymer electrolyte holding negative electrode A, the polymer electrolyte holding positive electrode unit, the polymer electrolyte holding negative electrode A, the polymer electrolyte holding positive electrode unit, and the polymer electrolyte holding negative electrode B were stacked in this order to obtain a stacked electrode group. .
At this time, the two negative electrode mixture layer forming portions of the polymer electrolyte holding negative electrode B were laminated so that they faced the inside of the laminated electrode group. That is, two polymer electrolyte holding negative electrodes B
Each of the negative electrode current collectors made of copper foil having a thickness of 50 μm was disposed on the outermost layer of the laminated electrode group.

FIG. 4 shows the laminated electrode group manufactured as described above. As shown in FIG. 4, this laminated electrode group is composed of five polymer electrolyte retaining positive electrode units 10 and six polymer electrolyte retaining negative electrodes 20, and the outermost polymer electrolyte retaining negative electrode 20 of the laminated electrode group is Both the upper and lower sides are based on the negative electrode B, and a 50 μm-thick copper foil is used for the electrode current collector of the negative electrode B, and the negative electrode mixture layer is formed only on one surface thereof. Are arranged toward the inside of the stacked electrode group, and the negative electrode current collector is arranged toward the outside of the stacked electrode group. The inner four polymer electrolyte-carrying negative electrodes 20 are based on the negative electrode A, and the negative electrode current collectors of these negative electrodes A are each made of a 10-μm-thick copper foil. Is formed. And, these six polymer electrolyte holding negative electrodes 20
Between the polymer electrolyte holding positive electrode units 10
Are arranged, and the laminated electrode group is composed of five polymer electrolyte-carrying positive electrode units 10 and six polymer electrolyte-carrying negative electrodes 20 (however, two of the outermost layers are based on the negative electrode B, and four inner electrodes are negative electrodes). A based on A). The white portion around the polymer electrolyte holding positive electrode unit 10 is shown to show that a nonwoven fabric is arranged as a support around the positive electrode in the production of the polymer electrolyte holding positive electrode unit 10.

As shown in FIG. 5, a protective film 4a, a metal foil 4b
A laminate film made of a heat-fusible resin film 4c is used. In the case 4 of the present embodiment, a nylon film having a thickness of 30 μm is used as the protective film 4a, and an aluminum foil having a thickness of 50 μm is used as the metal foil 4b. Used as the heat-fusible resin film 4c with a thickness of 30
A modified polyolefin film having a thickness of μm is used, and the aluminum foil of the metal foil 4b plays a role of a short-circuit forming plate and a heat dissipation promoting plate in the present invention, in addition to the original role of not allowing moisture or gas to pass therethrough. The nylon film of the protective film 4a serves as a protective layer for preventing the aluminum foil from being damaged or corroded from the outside, and the heat-fusible resin film 4c
The modified polyolefin film has a role of sealing the laminated electrode group by heat fusion.

The outer package 4 is used two times for the outer package of the above-mentioned laminated electrode group, and both have the same configuration. One of them is a flat plate, and the other is the above-mentioned one. In order to easily accommodate the laminated electrode group, the laminated electrode group is formed in a container shape with a flange, and the two exterior bodies 4, 4 are arranged so that the modified polyolefin films face each other inward while the laminated electrode group is interposed therebetween. It arrange | positions and seals by heating and heat-fusing the modified polyolefin film of a peripheral part.

The negative electrode leads 2c of the laminated electrode group covered with the package 4 as described above are connected in parallel as shown in FIG.
, And the other end of the negative electrode terminal 6 is drawn out of the sealed portion of the exterior body 4 to the outside.

On the other hand, also on the positive electrode side, as shown in FIG. 7, the lead portion 1c is connected in parallel, and the lead portion 1c and the aluminum foil of the package 4 are connected to one end of the positive electrode terminal 5, The other end of the positive electrode terminal 5 is drawn out through the sealing portion of the exterior body 4. Although both the positive electrode terminal 5 and the negative electrode terminal 6 are drawn in the same direction, there is a distance between them (that is, FIG.
The position of the cut surface of FIG. 7 is different from the position of the cut surface of FIG. 7). Under normal conditions, the positive terminal 5 and the negative terminal 6 do not come into contact with each other to cause a short circuit.

FIG. 8 is an enlarged view of a main part of the portion A (where the positive electrode terminal 5 is drawn out at the sealing portion of the exterior body 4) of FIG. 7, and based on FIG. The connection between the aluminum foil) and the positive electrode terminal 5 will be described.
The sealed portion of the exterior body 4 on which the positive electrode terminal 5 is arranged is ultrasonically heated to melt the modified polyolefin film as the heat-sealing resin film 4c of the inner layer of the exterior body 4, and the metal foil 4b (aluminum) of the exterior body 4 (Foil) and the positive electrode terminal 5.

COMPARATIVE EXAMPLE 1 A copper foil having a thickness of 10 μm was used as a negative electrode current collector of a negative electrode disposed in the outermost layer of the laminated electrode group, and the connection between the positive electrode terminal and the aluminum foil in the package was not made. Produced a laminated polymer electrolyte battery in the same manner as in Example 1.

A thermocouple was attached to the surfaces of the batteries of Example 1 and Comparative Example 1, placed on a V block, and a stainless steel nail having a shaft portion having a diameter of 3 mm was applied to the laminated electrode group at a speed of 5 mm / sec. The battery was pierced at a right angle, and the maximum temperature of the battery was measured. Table 1 shows the results.

[0054]

[Table 1]

As shown in Table 1, the maximum temperature of the battery of Example 1 was 135 ° C. and no smoke or ignition occurred.
The maximum temperature of the battery of Comparative Example 1 was 200 ° C. or higher, which was considerably higher than 150 ° C., at which the exothermic reaction was considered to run away.

In the above embodiment, the connection between the metal foil (aluminum foil) in the exterior body and the positive electrode terminal was made by ultrasonic welding, but other than the above-mentioned ultrasonic welding, resistance welding, caulking, screwing, etc. Can be done by However, ultrasonic welding is particularly preferred. The reason is that even without the pretreatment of peeling off the heat-fusible resin film (modified polyolefin film) as the innermost layer of the laminate film of the exterior body, the modified polyolefin film is melted by irradiating ultrasonic waves from outside the exterior body. This is because the connection between the aluminum foil in the laminate film of the outer package and the positive electrode terminal can be made. In the above-described embodiment, at the time of ultrasonic welding, a 947M model manufactured by Branson Corporation was used as an ultrasonic transmitter, and a weld energy of 80 Joules was applied for 2 seconds at an amplitude of 80% under a pressure of 4 kg / cm ^2. This condition can be changed variously according to the situation.

[0057]

As described above, according to the present invention, even if a short circuit occurs due to nail penetration or crushing, it is possible to provide a laminated polymer electrolyte battery that prevents smoke and ignition and has high safety.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically showing a positive electrode used in a laminated polymer electrolyte battery according to Example 1 of the present invention.

FIG. 2 is a cross-sectional view schematically showing a negative electrode A used in the laminated polymer electrolyte battery of Example 1 of the present invention.

FIG. 3 is a cross-sectional view schematically showing a negative electrode B used in the laminated polymer electrolyte battery of Example 1 of the present invention.

FIG. 4 is a cross-sectional view schematically illustrating a stacked electrode group used in the stacked polymer electrolyte battery of Example 1 of the present invention.

FIG. 5 is a cross-sectional view schematically showing an outer package used for the laminated polymer electrolyte battery of Example 1 of the present invention.

FIG. 6 is a cross-sectional view schematically showing a connection state between a lead portion of a negative electrode and a negative electrode terminal in the laminated polymer electrolyte battery of Example 1 of the present invention.

FIG. 7 is a cross-sectional view schematically showing a connection state between a lead portion of a positive electrode and a positive electrode terminal in the laminated polymer electrolyte battery of Example 1 of the present invention.

FIG. 8 is an enlarged view of a main part of a portion A in FIG. 7;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Positive electrode 1a Positive electrode collector 1b Positive electrode mixture layer 2 Negative electrode 2a Negative electrode collector 2b Negative electrode mixture layer 2c Lead part 3 Polymer electrolyte layer 4 Package 4a Protective film 4b Metal foil 4c Heat-fusible resin film 5 Positive electrode terminal 6 negative electrode terminal 10 polymer electrolyte holding positive electrode unit 20 polymer electrolyte holding negative electrode

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Hiroshi Yamamoto, 1-88 Ushitora, Ibaraki City, Osaka Prefecture Inside Hitachi Maxell Co., Ltd. (72) Tetsuo Kawai 1-188, Usutora, Ibaraki City, Osaka Hitachi Maxell F-term (reference) 5H022 AA09 CC04 CC08 CC09 CC19 KK04 5H025 AA00 CC01 CC02 CC11 CC18 CC22 CC31 5H029 AJ03 AJ12 AK03 AL07 AM00 AM03 AM04 AM05 AM07 AM16 BJ04 BJ12 CJ22 DJ02 DJ05 DJ07 EJ01 EJ12 HJ

Claims (1)

[Claims] A positive electrode having a positive electrode mixture layer formed on at least one surface of a positive electrode current collector, and a negative electrode having a negative electrode mixture layer formed on at least one surface of a negative electrode current collector, A laminated polymer electrolyte battery in which a laminated electrode group laminated with a polymer electrolyte layer interposed therebetween is packaged with a package including a metal foil, wherein the electrode of at least one outermost layer of the laminated electrode group is an electrode. The thickness of the current collector is 30 μm or more, an electrode mixture layer is not formed on the outer surface side, the electrode current collector is connected to a lead of an electrode having the same polarity, and the A laminated polymer electrolyte battery, wherein the thickness of the metal foil is 30 μm or more, and the other polarity electrode terminal is connected to the metal foil in the outer package.