JP3583592B2 - Thin rechargeable battery - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a thin secondary battery, and more particularly, to a thin secondary battery provided with a gas release mechanism.
[0002]
[Prior art]
In recent years, thin secondary batteries having a thickness of about 0.5 mm, such as polymer lithium ion secondary batteries, have been attracting attention as power supplies for cordless devices such as portable personal computers that emphasize small size and light weight. It is being actively promoted.
[0003]
Important elemental technologies for putting the thin secondary battery into practical use include selection of active materials for the positive electrode and the negative electrode, a technology for forming a battery, and a technology for sealing a thin power generating element pond with an exterior material. When the sealing property of the thin power generating element by the exterior material is reduced, not only does the electrolytic solution constituting the power generating element volatilize and leak to reduce the battery reaction, but also moisture easily enters from the outside to reduce the performance. Invite.
[0004]
For this reason, the conventional thin secondary battery is characterized in that a thin power generating element having a positive electrode, a separator and a negative electrode in an exterior material in which a heat-fusible resin film is disposed on the inner surface is used for collecting the positive and negative electrodes. An external terminal connected to a body is housed so as to extend from an opening edge of the exterior material, and the heat-fusible resin films are heat-sealed to each other at the opening edge, thereby attaching the power generation element to the exterior. It has a structure sealed inside the material. The exterior material is, for example, a laminated film in which a heat-fusible resin film, a barrier film such as an aluminum foil, and a rigid resin film such as a polyethylene terephthalate film are laminated at least in this order.
[0005]
However, when gas is generated inside the thin secondary battery due to overcharging or the like, the internal pressure increases. For this reason, the laminated film as an exterior material expands and eventually bursts. When a thin secondary battery ruptures, its contents (especially electrolyte) are scattered, and the device is damaged when mounted directly on the device, and the case is damaged for a battery pack. Cause damage.
[0006]
[Problems to be solved by the invention]
The present invention provides a thin secondary battery that can easily escape to the outside when a gas is generated and the internal pressure rises at the time of overcharging or the like to prevent rupture, thereby preventing the gas from exploding. It is what we are going to offer.
[0007]
[Means for Solving the Problems]
The thin secondary battery according to the present invention has a positive electrode, a separator , a negative electrode, and a non-aqueous solution in an exterior material composed of a laminated film in which a heat-fusible resin film, a metal foil, and a rigid resin film are laminated in this order from the inner surface side. A thin secondary battery in which external terminals electrically connected to the positive and negative electrodes, respectively, having a thin power generating element having an electrolyte are housed so as to extend from an opening edge of the exterior material,
The heat-fusible resin films are heat-sealed to each other at all of the opening edges of the laminated film, and the power-generating element is sealed in the housing material by the heat-sealed seal portion; to partially open the pores of the heat-fusible resin film except for the sealing portion of the timber, further the unbonded state resin film portion having a rigidity of the outer member opposite to said metal foil into the hole In addition, a cutout portion is provided in the resin film portion in the non-adhered state.
[0008]
Another thin secondary battery according to the present invention is a heat-fusible resin film from the inner surface side, a metal foil and a resin film having rigidity in an exterior material consisting of a laminated film laminated in this order, a positive electrode, a separator , a negative electrode and A thin secondary battery in which thin-type power generating elements having a non-aqueous electrolyte are housed such that external terminals electrically connected to the positive and negative electrodes respectively extend from an opening edge of the exterior material,
The heat-fusible resin films are heat-sealed to each other at all of the opening edges of the laminated film, and the power-generating element is sealed in the housing material by the heat-sealed seal portion; A hole is opened in a part of the heat-fusible resin film and a part of the rigid resin film excluding the seal portion of the material so as to at least oppose each other.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a thin secondary battery according to the present invention, for example, a thin polymer electrolyte secondary battery will be described in detail with reference to the drawings.
1 is a perspective view showing a thin polymer electrolyte secondary battery according to the present invention, FIG. 2 is an exploded perspective view of the secondary battery shown in FIG. 1, FIG. 3 is a cross-sectional view taken along line III-III in FIG. FIG. 4 is a sectional view taken along the line IV-IV in FIG.
[0010]
As shown in FIG. 3, a thin power generating element 5 is provided in an exterior material 4 composed of a laminated film in which a heat-fusible resin film 1, a metal foil 2, and a rigid resin film 3 are laminated in this order from the inner surface side. The power generation element 5 is sealed by sealing portions 6a, 6b and 6c which are housed and heat-fused with the heat-fusible resin film 1 on the inner surface of, for example, three sides of the exterior material 4. The power generating element 5 has a structure in which a positive electrode 7, a polymer electrolyte layer 8 as a separator, and a negative electrode 9 are laminated in this order.
[0011]
The positive electrode 7 has a structure in which a positive electrode layer 11 is supported on both surfaces of a current collector 10 made of aluminum. The current collector 10 has a terminal portion 12 made of strip-shaped aluminum foil, and an external positive electrode lead 13 made of aluminum is connected to the terminal portion 12 by ultrasonic welding. The external lead 13 extends outside from the sealing portion 6b of the exterior material 4.
[0012]
The negative electrode 9 has a structure in which a negative electrode layer 15 is supported on both surfaces of a copper current collector 14. The current collector 14 has a terminal portion 16 made of a strip-shaped copper foil, and an external negative electrode lead 17 is connected to the terminal portion 16 by ultrasonic welding or the like. The external lead 17 extends outside from the sealing portion 6b of the exterior material 4.
[0013]
A hole, for example, a circular hole 18 is provided in the heat-fusible resin film 1 on the inner surface of the exterior material 4 corresponding to the surface of the power generating element 5 as shown in FIGS. A portion of the resin film 3 having rigidity of the exterior material 4 facing the circular hole 18 is in a non-adhered state with respect to the metal foil 2 and a cut portion, for example, a cross-shaped cut portion 19 is formed of the resin in the non-adhered state. It is provided on the film part 3.
[0014]
Such a thin polymer electrolyte secondary battery is manufactured, for example, by the following method.
First, a circular hole 18 is punched in a predetermined portion of the heat-fusible resin film, and a metal foil is heat-sealed to the resin film. Subsequently, after a cut portion, for example, a cross-shaped cut portion 19 is formed by a cross-shaped punch or the like at a position corresponding to the circular hole of the rigid resin film, the cut portion of the resin film is formed on the metal foil. Dry lamination is performed so as to be in an unbonded state, and a strip-shaped laminated film 20 having, for example, a three-layer structure is manufactured. Subsequently, the thin film power generating element 5 to which the positive and negative external terminals 13 and 17 are attached is connected to the laminated film 20 in which the circular hole 18 is not opened with respect to a bending line 21 located at a central portion parallel to the short side. After the external terminals 13 and 17 are mounted on the portion so as to extend from the end face of the short side of the laminated film 20, the laminated film 20 is bent so as to wrap the power generating element 5 at the bending line 21. Then, the three sides excluding the bent portion are heat-sealed to seal the power generating element 5, thereby producing the secondary battery shown in FIG.
[0015]
The package 4, the positive electrode 7, the negative electrode 9, and the electrolyte layer 8 have the following configuration.
1) Exterior material 4
The exterior material 4 is a laminated film in which a heat-fusible resin film 1, a metal foil 2, and a rigid resin film 3 are laminated in this order from the inner surface side. As the heat-fusible resin, for example, polyethylene (PE), ionomer, ethylene vinyl acetate (EVA) and the like can be used. As the metal foil, for example, an Al foil, a Ni foil or the like can be used, but an Al foil that can be made thinner is preferable. As the rigid resin, for example, polyethylene terephthalate (PET), nylon or the like can be used. However, the rigid resin film may be a combination of two or more films.
[0016]
Specific laminated films include a laminated film of PE / Al foil / PET laminated from the sealing surface side to the outer surface; a laminated film of PE / Al foil / nylon; a laminated film of ionomer / Al foil / PET; A laminated film of Al foil / nylon; a laminated film of ionomer / Ni foil / PET; a laminated film of EVA / Al foil / PET can be used.
[0017]
The exterior material is formed by bending the laminated film so that the heat-fusible resin film is positioned on the inner surface (sealing surface), and heat-sealing the end parallel to the bending line to produce a cylindrical body. The thin-type power generating element described above is housed so that the external terminal electrically connected to the positive electrode extends from one opening and the external terminal electrically connected to the negative electrode extends from the other opening. The two openings may be heat-sealed to seal the power generating element.
[0018]
2) Positive electrode 7
The positive electrode 7 has a structure in which a positive electrode layer 11 containing an active material, a non-aqueous electrolyte and a polymer holding the electrolyte is supported on both surfaces of a current collector 10 made of aluminum.
[0019]
Examples of the active material include various oxides (eg, lithium manganese composite oxide such as LiMn ₂ O ₄ , manganese dioxide, lithium-containing nickel oxide such as LiNiO ₂ , lithium-containing cobalt oxide such as LiCoO ₂ , lithium Nickel-cobalt oxide, amorphous vanadium pentoxide containing lithium, etc.) and chalcogen compounds (eg, titanium disulfide, molybdenum disulfide, etc.). Among them, it is preferable to use a lithium manganese composite oxide, a lithium-containing cobalt oxide, and a lithium-containing nickel oxide.
[0020]
The non-aqueous electrolyte is prepared by dissolving an electrolyte in a non-aqueous solvent.
Examples of the non-aqueous solvent include ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), and γ-butyrolactone (γ- BL), sulfolane, acetonitrile, 1,2-dimethoxyethane, 1,3-dimethoxypropane, dimethyl ether, tetrahydrofuran (THF), 2-methyltetrahydrofuran and the like. The non-aqueous solvents may be used alone or as a mixture of two or more.
[0021]
Examples of the electrolyte include lithium perchlorate (LiClO ₄ ), lithium hexafluorophosphate (LiPF ₆ ), lithium borotetrafluoride (LiBF ₄ ), lithium arsenic hexafluoride (LiAsF ₆ ), and trifluoromethanesulfonic acid. Lithium salts such as lithium (LiCF ₃ SO ₃ ) and lithium bistrifluoromethylsulfonylimide [LiN (CF ₃ SO ₃ ) ₂ ] can be given.
[0022]
The amount of the electrolyte dissolved in the non-aqueous solvent is desirably 0.2 mol / L to 2 mol / L.
Examples of the polymer holding the non-aqueous electrolyte include a polyethylene oxide derivative, a polypropylene oxide derivative, a polymer containing the derivative, and a copolymer of vinylidene fluoride (VdF) and hexafluoropropylene (HFP). Can be. The copolymerization ratio of the HFP depends on the method of synthesizing the copolymer, but is usually at most about 20% by weight.
[0023]
The positive electrode layer may include a conductive material from the viewpoint of improving conductivity. Examples of the conductive material include artificial graphite, carbon black (eg, acetylene black), nickel powder, and the like.
[0024]
As the current collector, for example, aluminum expanded metal, aluminum mesh, aluminum punched metal, or the like can be used.
The positive electrode may have a structure in which a positive electrode layer is supported on one surface of a current collector.
[0025]
3) Negative electrode 9
The negative electrode 9 has a structure in which a negative electrode layer 15 containing an active material, a non-aqueous electrolyte, and a polymer holding the electrolyte is supported on both surfaces of a current collector 14 made of copper.
[0026]
Examples of the active material include carbonaceous materials that occlude and release lithium ions. Such carbonaceous materials include, for example, those obtained by firing organic polymer compounds (eg, phenolic resin, polyacrylonitrile, cellulose, etc.), those obtained by firing coke and mesophase pitch, and those made by artificial graphite. And carbonaceous materials represented by natural graphite and the like. Among them, it is preferable to use a carbonaceous material obtained by firing the mesophase pitch at a temperature of 500 ° C to 3000 ° C under normal pressure or reduced pressure.
[0027]
As the non-aqueous electrolyte and the polymer, the same ones as described for the positive electrode described above are used.
The negative electrode layer is allowed to contain conductive materials such as artificial graphite, natural graphite, carbon black, acetylene black, Ketjen black, nickel powder, and polyphenylene derivatives, and fillers such as olefin polymers and carbon fibers.
[0028]
As the current collector, for example, a copper expanded metal, a copper mesh, a copper punched metal, or the like can be used.
The negative electrode may have a structure in which a positive electrode layer is supported on one surface of a current collector.
[0029]
4) Polymer electrolyte layer 8
The electrolyte layer 8 includes a non-aqueous electrolyte and a polymer that holds the electrolyte.
As the non-aqueous electrolyte and the polymer, the same ones as described for the positive electrode described above are used.
[0030]
The electrolyte layer may include an inorganic filler such as SiO ₂ powder to improve compressive strength.
The power generation element is not limited to one layer, and two or more layers may be housed in the exterior material.
[0031]
The hole opened in the heat-fusible resin film of the exterior material is not limited to a circle, but may be a rectangle, a polygon, or the like.
The cut portion provided in the rigid resin film of the exterior material is not limited to a cross shape, but may be a linear shape.
[0032]
Next, another thin secondary battery according to the present invention, for example, a thin polymer electrolyte secondary battery will be described with reference to FIGS.
FIG. 5 is a perspective view showing another thin polymer electrolyte secondary battery according to the present invention, and FIG. 6 is a sectional view taken along the line VI-VI in FIG. The same members as those in FIGS. 1 to 4 described above are denoted by the same reference numerals, and description thereof will be omitted.
[0033]
The thin polymer electrolyte secondary battery has holes (for example, circular holes) 22 in a part of the heat-fusible resin film 1 and the rigid resin film 3 of the exterior member 4 located on the surface of the thin power generating element 5, 23 are open to face each other. That is, the metal foil 2 constituting the exterior material 4 is exposed from the inner surface and the outer surface at the circular holes 22 and 23.
[0034]
The hole is not limited to a circle, but may be a rectangle, a polygon, or the like.
The holes (for example, circular holes) opened in a part of the heat-fusible resin film and the rigid resin film do not necessarily have to have the same dimensions. For example, the holes are opened in the heat-fusible resin film. The round hole formed may be larger than the circular hole opened in the rigid resin film.
[0035]
In addition, in order to increase the volume energy density of the thin secondary battery, the external terminals 13 and 17 of FIG. 1 or FIG. 5 are bent and fixed to the surfaces of the parallel seal portions 6a and 6c except for the seal portion 6b to which the external terminals 13 and 17 extend. You may.
[0036]
According to the present invention shown in FIGS. 1 to 4 described above, a circular hole 18 is opened in the heat-fusible resin film 1 on the inner surface of the exterior material 4 in which the power generation element 5 is stored, and the circular hole 18 is opposed to the circular hole 18. The resin film 3 having the rigidity of the exterior material 4 is not bonded to the metal foil 2 and the resin film portion 3 in the non-bonded state is provided with, for example, a cross-shaped cut portion 19, so that overcharging is performed. Even if gas is generated from the power generating element 5 due to the above, the internal pressure rises, the external material 4 itself is broken at the location of the metal foil 2 of the external material 4 where the circular hole 18 and the cross-shaped cut 19 are located. Gas can escape before it bursts.
[0037]
That is, as shown in FIG. 7, when gas is generated inside the exterior material 4 and the exterior material 4 expands, the exterior material 4 exposed from the circular hole 18 of the heat-fusible resin film 1 of the exterior material 4 is removed. The metal foil 2 is bent outward, and the unbonded rigid resin film 3 portion located in the metal foil 2 facing the circular hole 18 is opened outward along the cut portion 19, thereby opening the hole. It is formed. As a result, a force is applied to the metal foil 2 to bend outward toward the hole, so that the metal foil 2 is finally broken without being able to withstand the force.
[0038]
Therefore, when a gas is generated at the time of overcharging and the internal pressure is increased, the gas is easily escaping to the outside due to the breakage of the metal foil constituting the exterior material, and the exterior material is prevented from rupture. Can be prevented. For this reason, it is possible to provide a thin secondary battery capable of avoiding scattering of contents (especially, an electrolytic solution) due to the rupture of the exterior material, and preventing damage to the device when directly mounted on the device.
[0039]
On the other hand, according to the present invention shown in FIGS. 5 and 6, circular holes 22 and 23 are formed in a part of the heat-fusible resin film 1 and the rigid resin film 3 of the exterior material 4 in which the thin power generating element 5 is housed. When the exterior material 4 expands due to gas generation due to overcharging or the like by opening at least facing each other, the exterior material 4 exposed from the inner surface side and the outer surface side at the circular holes 22 and 23 is provided. Since the metal foil 2 is subjected to a force curving outward toward the outer recording hole 23, the metal foil 2 is finally broken without being able to withstand the force. As a result, when a gas is generated and the internal pressure rises, the gas is easily escaping to the outside due to the breakage of the metal foil constituting the exterior material, thereby preventing the exterior material from being ruptured. it can. Therefore, it is possible to provide a thin secondary battery capable of avoiding scattering of contents (especially, an electrolytic solution) due to the rupture of the exterior material and preventing damage to the device when directly mounted on the device.
[0040]
【Example】
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.
(Example 1)
<Preparation of positive electrode>
A powder of vinylidene fluoride-hexafluoropropylene (VdF-HFP) copolymer (trade name: KYNAR2801, a copolymerization ratio [VdF: HFP] of 88:12, manufactured by Elphatochem Co., Ltd.) is dissolved in acetone, and the powder is dissolved in the acetone solution. Dibutyl phthalate (DBP) and lithium-containing cobalt oxide (manufactured by Nippon Heavy Industries, Ltd.) having a composition formula of LiCoO ₂ as an active material were added to prepare a positive electrode paste. Subsequently, a positive electrode paste of the above composition was applied to a porous current collector made of an aluminum mesh using a knife coater, and dried with dry air to form a positive electrode impregnated with no electrolyte on both surfaces of the porous current collector. A positive electrode material on which a layer was formed was produced.
[0041]
<Preparation of negative electrode>
The same vinylidene fluoride-hexafluoropropylene copolymer as used for the positive electrode was dissolved in acetone to prepare an acetone solution, and then dibutyl phthalate (DBP) was added to the acetone solution. A negative electrode paste was prepared by adding and mixing mesophase pitch-based carbon fibers (manufactured by Petka Corporation). This negative electrode paste was coated on a porous current collector made of a copper mesh using a knife coater, and dried with dry air to form a negative electrode having an electrolyte-impregnated negative electrode layer formed on both surfaces of the porous current collector. The material was made.
[0042]
<Preparation of solid polymer electrolyte layer>
After dissolving the same copolymer of vinylidene fluoride-hexafluoropropylene as used for the positive electrode in acetone to prepare an acetone solution, dibutyl phthalate (DBP) is added to the acetone solution, and then mixed. Thus, a paste for an electrolyte layer was prepared. The paste was applied on a smooth glass plate, dried in the same manner as the positive and negative electrodes, and peeled off from the glass plate to prepare a solid polymer electrolyte material not impregnated with an electrolyte.
[0043]
<Preparation of non-aqueous electrolyte>
LiPF ₆ as an electrolyte is dissolved in a non-aqueous solvent in which ethylene carbonate (EC) and dimethyl carbonate (DMC) are mixed at a volume ratio of 1: 1 so as to have a concentration of 1 mol / l. A liquid was prepared.
[0044]
The obtained positive electrode material, solid polymer electrolyte material and negative electrode material are stacked in this order, and they are laminated by heating and pressing with a rigid roll heated to 130 ° C. to have a thickness of 1.0 mm and an outer dimension of 40 mm × 60 mm. The body was made. Subsequently, the laminate was immersed in methanol to elute DBP in the positive electrode material, the negative electrode material, and the polymer electrolyte material, and these members were used as a porous electrolyte-impregnated power generating element having a porous structure. Subsequently, external terminals were respectively connected to the strip-shaped terminal portions of the positive and negative porous current collectors of the power generation element by ultrasonic welding or the like.
[0045]
Next, a circular hole having an outer diameter of 6 mm was punched out at a location 35 mm inward from the long side and 43 mm inward from the short side of a band-shaped ionomer resin film having a thickness of 50 μm and an outer dimension of 70 mm × 153 mm, and the resin film having a thickness of 10 μm. The Al foil was heat-sealed. Subsequently, after forming a cross-shaped notch of 5 mm in length and width with a cross-shaped punch at a position corresponding to the circular hole of the PET film having a thickness of 12 μm, the cut portion of the resin film was not adhered to the Al foil. Dry lamination was performed to obtain a three-layered band-like laminated film. Subsequently, after mounting the electrolyte-unimpregnated power generating element to which the external terminals of the positive and negative electrodes are attached so that the external terminals extend from the short side of the laminated film, the laminated film is parallel to the short side at the center. Was folded so as to enclose the electrolyte-unimpregnated power generating element. Subsequently, three sides having a width of 10 mm except for the bent portion were heat-sealed. However, a part of one of the two sides except the side from which the external terminal extends was left as an unsealed portion. Thereafter, the non-aqueous electrolyte is injected into the interior through the unsealed portion, and the unsealed portion is again heat-sealed to form the thin power generating element 5 in the exterior material 4 made of the laminated film shown in FIG. Are sealed and housed, and a circular hole 18 is formed in the ionomer resin film 1 of the exterior material 4 corresponding to the surface of the power generating element 5, and a cross-shaped cut portion is formed in the PET film 3 of the exterior material 4 opposed to the circular hole 18. 100 thin polymer electrolyte secondary batteries having a thickness of 1.2 mm, external dimensions of 70 mm × 75 mm excluding external terminals, and an electric capacity of 100 mAh were provided.
[0046]
(Example 2)
With the same configuration as in Example 1 except that a circular hole having an outer diameter of 5 mm was opened in the PET film instead of the cut portion, 100 thin polymer electrolyte secondary batteries shown in FIG. 5 described above were manufactured. .
[0047]
(Comparative Example 1)
100 thin polymer electrolyte secondary batteries having the same dimensions and electric capacity as in Example 1 were manufactured except that a circular hole was not formed in the ionomer resin film of the laminated film and a cut portion was not formed in the PET film.
[0048]
Each of the obtained secondary batteries of Examples 1 and 2 and Comparative Example 1 was placed in a polypropylene case with external connection terminals having an internal space of 72 mm × 77 mm × 4.0 mm and external dimensions of 75 mm × 80 mm × 6.0 mm. The battery pack is assembled by storing the external terminals of the positive and negative electrodes so as to be connected to the external connection terminals.
[0049]
An overcharge test was performed on each of the pack-type batteries under the conditions of 1 C and 3 hours, and the amount of deformation of the battery pack case in the thickness direction was measured. The results are shown in Table 1 below.
Table 1
Case deformation number Average deformation amount of deformed case Example 10 0 −
Example 20 0 −
Comparative Example 1 100 2.4 mm
As is apparent from Table 1, when the thin secondary batteries of Examples 1 and 2 were formed into a pack type battery, no deformation of the case was observed. On the other hand, when the thin secondary battery of Comparative Example 1 was a pack-type battery, deformation was observed in 100 out of 100 batteries. Note that when the pack-type batteries of Examples 1 and 2 were disassembled and the thin polymer electrolyte secondary batteries inside the case were examined, all the secondary batteries had circular holes opened in the ionomer resin film constituting the exterior material. It was found that the Al foil was broken at the location of the Al foil exposed from the.
[0050]
【The invention's effect】
As described in detail above, according to the present invention, when gas is generated at the time of overcharging and the internal pressure increases, it is possible to prevent the gas from easily escaping to the outside and rupture. A highly safe thin secondary battery can be provided.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a thin polymer electrolyte secondary battery according to the present invention.
FIG. 2 is an exploded perspective view of the secondary battery of FIG.
FIG. 3 is a sectional view taken along the line III-III in FIG. 1;
FIG. 4 is a sectional view taken along the line IV-IV in FIG. 1;
FIG. 5 is a perspective view showing another thin polymer electrolyte secondary battery according to the present invention.
FIG. 6 is a sectional view taken along the line VI-VI in FIG. 5;
FIG. 7 is a partial cross-sectional view for explaining the operation of the thin polymer electrolyte secondary battery according to the present invention.
[Explanation of symbols]
1: heat-fusible resin film,
2 ... metal foil,
3 ... a rigid resin film,
4 ... exterior material,
5. Thin power generation element,
7 ... positive electrode,
8 ... polymer electrolyte layer,
9 ... negative electrode,
13, 17 ... external terminals,
18, 22, 23 ... circular holes,
19: Notch.

Claims (2)

From the inner surface side, a thin power generating element having a positive electrode, a separator , a negative electrode, and a non-aqueous electrolyte is placed in an outer package made of a laminated film in which a heat-fusible resin film, a metal foil, and a rigid resin film are laminated in this order. An external terminal electrically connected to each negative electrode is a thin secondary battery housed so as to extend from an opening edge of the exterior material,
The heat-fusible resin films are heat-sealed to each other at all of the opening edges of the laminated film, and the power-generating element is sealed in the housing material by the heat-sealed seal portion; to partially open the pores of the heat-fusible resin film except for the sealing portion of the timber, further the unbonded state resin film portion having a rigidity of the outer member opposite to said metal foil into the hole In addition, a notched portion is provided in the resin film portion in the non-adhered state. From the inner surface side, a thin power generating element having a positive electrode, a separator , a negative electrode, and a non-aqueous electrolyte is placed in an outer package made of a laminated film in which a heat-fusible resin film, a metal foil, and a rigid resin film are laminated in this order. An external terminal electrically connected to each negative electrode is a thin secondary battery housed so as to extend from an opening edge of the exterior material,
The heat-fusible resin films are heat-sealed to each other at all of the opening edges of the laminated film, and the power-generating element is sealed in the housing material by the heat-sealed seal portion; A thin secondary battery characterized in that holes are opened at least in portions of the heat-fusible resin film and the rigid resin film except for the seal portion of the material, respectively.

Images