JP2002251989A - Lithium ion polymer secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce resistance in a terminal joint while securing flexibility. SOLUTION: A plurality of positive electrode collector foils 12 and a plurality of negative electrode collector foils 15 are laminated via a polymer electrolyte layer 17. One end parts 12b of the plurality of positive electrode collector foils and other end parts 15a of the plurality of negative electrode collector foils 15 are respectively laminated. One end of a positive electrode terminal 23 is inserted between all laminated one end parts of the plurality of positive electrode collector foils, and the one end of the positive electrode terminal 23 is connected in an inserted state with all one end parts 12b of the plurality of positive electrode collector foils 12 by a plurality of caulked eyelets 25 with predetermined intervals t in a direction crossing an inserting direction. One end of a negative electrode terminal 21 is inserted between all laminated other end parts 15a of the plurality of negative electrode collector foils, and the one end of the negative electrode terminal 21 is connected in an inserted state with all other end parts 15a of the plurality of negative electrode collector foils 15 by a plurality of caulked eyelets 25 with the predetermined intervals t in the direction crossing an inserting direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a lithium ion polymer secondary battery in which a positive electrode active material and a negative electrode active material are laminated via a polymer electrolyte layer.

[0002]

2. Description of the Related Art Conventionally, with the spread of portable devices such as video cameras and notebook personal computers, demand for thin and somewhat flexible batteries has been increasing. As this thin battery, a lithium ion polymer secondary battery formed by laminating a positive electrode sheet and a negative electrode sheet is known. The positive electrode sheet is made by applying an active material to the surface of a positive electrode current collector foil, and the negative electrode sheet is made by applying an active material to the surface of a negative electrode current collector foil. A polymer electrolyte layer is interposed between the active material of the positive electrode sheet and the active material of the negative electrode sheet. In this battery, a positive electrode terminal and a negative electrode terminal for extracting a potential difference in each active material as a current are provided on the positive electrode current collector foil and the negative electrode current collector foil,
By sealing the stacked body thus stacked with a package, a lithium ion polymer secondary battery is produced. In this lithium ion polymer secondary battery, desired electricity can be obtained by using the positive electrode terminal and the negative electrode terminal drawn out of the package as terminals of the battery.

In recent years, there has been a tendency to increase the discharge capacity of lithium ion polymer secondary batteries. A plurality of positive electrode sheets and a plurality of negative electrode sheets are stacked to increase the discharge capacity, or the discharge capacity is increased. The area of the positive electrode sheet and the single negative electrode sheet is increased, and the expanded positive electrode sheet and the negative electrode sheet are folded into a desired size to increase the discharge capacity. On the other hand, by using or folding a plurality of positive electrode sheets and negative electrode sheets to expand the discharge capacity, the ends of the plurality of positive electrode current collector foils and the negative electrode current collector foils drawn out in layers are connected to each other. It is necessary to connect the positive terminal and the negative terminal. As this connection means, the ends of a plurality of positive electrode current collector foils and negative electrode current collector foils drawn out in layers are separated and bundled, and the bundled ends are sandwiched by a conductor also serving as a terminal, and bundled. A secondary battery has been proposed in which an end is welded to a conductor to extract electricity through the conductor (Japanese Patent Application Laid-Open No. Hei 7-26302).
9).

[0004]

However, when all the ends of the bundled positive electrode current collector foil or negative electrode current collector foil are joined to the conductor by welding, the mechanical strength at the joint is reduced by welding. And the flexibility of the battery is lost. In particular, when a conductor made of a rod-shaped metal piece is used, there is a disadvantage that the flexibility at the joint is completely lost. Conversely, when sandwiched between relatively flexible conductors and the ends that are bundled with the conductors are partially welded, the flexibility of the battery can be maintained, but welding is performed by bending the battery. There is a problem that a gap is formed between the end portion other than the portion and the conductor sandwiched from the outside, the conductivity in that portion is lost, and as a result, the resistance value increases and sufficient power cannot be obtained.
An object of the present invention is to provide a lithium ion polymer secondary battery that can reduce resistance at a terminal junction while ensuring flexibility.

[0005]

According to the first aspect of the present invention,
As shown in FIGS. 1 and 4, a positive electrode active material 13 is applied to each surface of a plurality of positive electrode current collector foils 12, and a negative electrode active material 16 is applied to each surface of a plurality of negative electrode current collector foils 15. A plurality of positive electrode current collector foils 12 and a plurality of negative electrode current collector foils 15 are laminated between a positive electrode active material 13 and a negative electrode active material 16 via a polymer electrolyte layer 17, respectively. One end of a sheet-like positive electrode terminal 23 is connected to all one ends 12b of the plurality of positive electrode current collector foils 12 protruding from one end 15b, and from the other end 12a of the positive electrode current collector foil 12 All other ends 15 of the plurality of projecting negative electrode current collector foils 15
A laminate of the positive electrode current collector foil 12 and the negative electrode current collector foil 15 is connected to one end of the sheet-shaped negative electrode terminal 21 so that the other end of the positive electrode terminal 23 and the other end of the negative electrode terminal 21 are exposed. Is an improvement of the lithium ion polymer secondary battery sealed by the package 26.

The characteristic configuration is such that all one end portions 12b of the plurality of positive electrode current collector foils 12 and all the other end portions 15a of the plurality of negative electrode current collector foils 15 are laminated, and the positive electrode terminal 23 Are inserted between all the one end portions 12b of the plurality of positive electrode current collector foils 12 stacked and caulked at predetermined intervals t in a direction intersecting the insertion direction in the inserted state. One end of the positive electrode terminal 23 is connected to one end 12b of all of the plurality of positive electrode current collector foils 12 by a clasp 25, and one end of the negative electrode terminal 21 is connected to the plurality of negative electrode current collector foils 15.
The negative electrode terminal 2 is inserted by a plurality of staples 25 inserted between all the other end portions 15a stacked together and crimped at a predetermined interval t in a direction intersecting the insertion direction in the inserted state.
One end is connected to all the other ends 15 a of the plurality of negative electrode current collector foils 15.

According to the first aspect of the present invention, all one end portions 12b of the plurality of positive electrode current collector foils 12 and all the other end portions 15a of the plurality of negative electrode current collector foils 15 are laminated. , The positive electrode terminal 23 and the negative electrode terminal 21 are connected by a plurality of staples 25 caulked at a predetermined interval t.
The increase in mechanical strength can be suppressed as compared with the case where all parts of the secondary battery 15b are joined.
0 can have the conventional flexibility. In addition, one end of the positive electrode terminal 23 is inserted between all the one end portions 12 b of the plurality of positive electrode current collector foils 12, and one end of the negative electrode terminal 21 is connected to the plurality of negative electrode current collector foils 15. The positive electrode terminal 2 is inserted between all the other ends 15a even if the secondary battery 10 is repeatedly bent.
3 and the positive electrode current collector foil 12 sandwiching the positive electrode terminal 23,
Alternatively, there is no gap between the negative electrode terminal 21 and the negative electrode current collector foil 15 sandwiching the negative electrode terminal 21, the conductivity at the contact portion is ensured, and the resistance at the terminal junction can be sufficiently reduced. .

The invention according to claim 2 is the invention according to claim 1, wherein the positive electrode terminal 23 and the negative electrode terminal 21 are expanded metal or perforated metal sheets, respectively. . In the invention according to claim 2, the flexibility of the sheet-shaped secondary battery 10 is ensured by ensuring the flexibility of the terminals 21 and 23 themselves, and the adhesion to the package 26 is improved. The sealing performance of the secondary battery by the package 26 can be ensured.

The invention according to claim 3 is the invention according to claim 1 or 2, wherein the same material as the material of the positive electrode current collector foil 12 or the material of the negative electrode current collector foil 15 is used. 0.5
The thickness of the reinforcing foil or the reinforcing thin plate 22 or 24 having a thickness of 2 mm is disposed on the laminated outer surface of one or both ends of the positive electrode current collector foil 12 or the negative electrode current collector foil 15 and the reinforcing foil or the reinforcing thin plate 22 is provided. , 24 through which a plurality of claws 25 are respectively caulked. According to the third aspect of the invention, the reinforcing foils or the reinforcing thin plates 22 and 2 are provided.
By arranging the secondary battery 4, when the secondary battery 10 is curved, it is possible to prevent breakage such as a crack in a caulked portion of the positive electrode current collector foil 12 and the negative electrode current collector foil 15 on the outside, and Reliability can be improved.

The reinforcing foils or the thin reinforcing plates 22 and 24 may be arranged only on one of the laminated outer surfaces of one or both ends of the positive electrode current collector foil 12 or the negative electrode current collector foil 15. It may be arranged on both laminated outer surfaces of the section. However, in the case where the reinforcing foil or the thin reinforcing plates 22 and 24 are arranged only on one of the laminated outer surfaces at the ends, it is necessary to dispose the reinforcing foil or the reinforcing thin plates 22 and 24 on the laminated outer surface on the side where the clasp 25 is crimped. Claw 25c with swaged eyelet 25
Of the end of the positive electrode current collector foil 12 or the negative electrode current collector foil 15 caused by contact with the reinforcing foil or the reinforcing thin plate 2
The reason is that it can be prevented by 2, 24. Here, when the thickness of the reinforcing thin plates 22 and 24 is less than 0.05 mm, there is a problem that the reinforcing foil or the reinforcing thin plates 22 and 24 are broken when the staple 25 is swaged, and the thickness is 0.5 mm. Is exceeded, there is a problem that the nail 25c which has swaged the staple 25 is difficult to stab. In addition, the more preferable thickness of the reinforcing thin plates 22 and 24 is 0.1 to 0.3 mm.

The invention according to claim 4 is the invention according to claims 1 to 3
The invention according to any one of the above, as shown in FIG. 2, a lithium ion polymer secondary battery in which the number of claws 25c of the swaged eye 25 is 5 to 15. According to the fourth aspect of the present invention, the number of the claws 25c is 5 to 15 so that the end portions 12b and 15a of the current collector foils 12 and 15 and the terminal 2
1, 23 bonding strength can be ensured. here,
If the number of the claws 25c of the caulked clasp 25 is less than 4, sufficient bonding strength cannot be obtained, and if the number exceeds 15, the positive electrode current collector foil 12 or the negative electrode current collector foil 15 may be damaged. There is. In addition, a more preferable number of the number of the claws 25c of the swaged diaper 25 is 7 to 10.

The invention according to claim 5 is the invention according to claims 1 to 4
In the invention according to any of the above, as shown in FIGS. 1 and 2, a value obtained by dividing the outer diameter d of the claw 25 c of the caulked diaper 25 by a predetermined interval t is 0.2 to 1.8. This is a lithium ion polymer secondary battery. In the invention according to claim 5, the positive electrode terminal 23 and the negative electrode terminal 21 can be bonded to one of the laminated end portions 12b and the other of the laminated end portions 15a under the most appropriate conditions. Relatively easy to manufacture secondary batteries. Here, if the value obtained by dividing the outer diameter d of the nail 25c by the predetermined interval t is less than 0.2, the positive electrode current collector foil 12 or the negative electrode current collector foil 15 may be damaged. If it exceeds 0.8, there is a problem that a sufficient bonding strength cannot be obtained.

[0013]

Embodiments of the present invention will now be described in detail with reference to the drawings. As shown in FIGS. 4 and 5,
The lithium ion polymer secondary battery 10 includes the positive electrode sheet 1
A polymer electrolyte layer 17 is interposed between the positive electrode sheet 1 and the negative electrode sheet 14, and the positive electrode sheet 11 and the negative electrode sheet 14 are laminated. The positive electrode sheet 11 has a positive electrode active material 13 applied to the surface of a positive electrode current collector foil 12, and the negative electrode sheet 14 has a negative electrode active material 16 applied to a surface of a negative electrode current collector foil 15. The polymer electrolyte layer 17 is interposed between the positive electrode active material 13 applied to the positive electrode current collector foil 12 and the negative electrode active material 16 applied to the surface of the negative electrode current collector foil 15. This lithium ion polymer secondary battery 10 uses a strip-shaped negative electrode current collector foil 15 in order to increase the discharge capacity. The strip-shaped negative electrode current collector foil 15 has a polymer electrolyte layer 17 on the surface of a negative electrode active material 16. It is folded with it. The negative electrode current collector foil 15 in this embodiment is a Cu foil, and the negative electrode active material 16 is a graphite-based active material.

As shown in FIGS. 9 (a) and 9 (b), a specific procedure for forming the negative electrode active material 16 on the surface of the negative electrode current collector foil 15 was prepared by dispersing and mixing the active material in a solution. The slurry is applied to the upper surface of the strip-shaped negative electrode current collector foil 15 by a doctor blade method and dried. On the other hand, the negative electrode active material 16 is formed on the upper surface of the negative electrode current collector foil 15 in the drawing, which is the surface except for the other side portion 15b, and the polymer electrolyte layer 17 is formed by applying an electrolyte slurry on the upper surface of the negative electrode active material 16 and drying. It is made by doing. The polymer electrolyte layer 17 is formed so as to have an area covering the negative electrode active material 16. Specifically, as shown in FIG. 9C, an electrolyte slurry is applied so as to cover the negative electrode active material 16, and then dried to form an area covering the negative electrode active material 16.

Returning to FIG. 5, the lithium ion polymer secondary battery 10 has a plurality of positive electrode sheets each having an area corresponding to the folded area between the polymer electrolyte layers 17 excluding the folds of the folded negative electrode sheet 14. 11 is pinched.
The polymer electrolyte layer 17 is also formed on the surface of the positive electrode active material 13 of the sandwiched positive electrode sheet 11. The positive electrode current collector foil 12 in this embodiment is an Al foil, and the positive electrode active material 1
For example, LiCoO ₂ is used for 3.

As shown in FIGS. 8 (a) and 8 (b), a specific procedure for preparing the positive electrode sheet 11 is to apply a slurry obtained by dispersing and mixing an active material in a solution by a doctor blade method and dry the slurry. Strip-shaped Al to be used as cathode current collector foil
First, the positive electrode active material 13 is formed on the upper surface of the foil 18. The positive electrode active material 13 is formed except for one side of the Al foil 18,
The polymer electrolyte layer 17 is formed to have an area covering the positive electrode active material 13. Specifically, FIG.
As shown in (c), the electrolyte slurry contains the positive electrode active material 13.
Is applied so as to cover the positive electrode active material 13 and then dried to form an area covering the positive electrode active material 13. Then Figure 8
As shown in (d), the strip-shaped Al foil 18 having the positive electrode active material 13 and the polymer electrolyte layer 17 forms the negative electrode sheet 14 together with the positive electrode active material 13 and the polymer electrolyte layer 17.
Is cut so as to have an area corresponding to the folded area. As a result, the positive electrode active material 13 is formed on the surface of the positive electrode current collector foil 12, and a plurality of positive electrode sheets 11 having a predetermined area and having the polymer electrolyte layer 17 on the surface of the positive electrode active material 13 are formed.

Next, as shown in FIG. 7, a polymer electrolyte layer 17 is interposed between the positive electrode sheet 11 and the negative electrode sheet 1.
4 are stacked. This lamination is performed by thermocompression bonding. That is, a plurality of positive electrode sheets 11 are arranged on the negative electrode sheet 14 at a predetermined pitch corresponding to the interval between the folds, and a pair of rollers 19, 19, which are heated to a predetermined temperature and rotate in opposite directions, are heated in this state. The positive electrode sheet 11 and the negative electrode sheet 14 are thermocompression-bonded with the polymer electrolyte layer 17 interposed therebetween as shown by the solid line arrows in the figure. The arrangement of the plurality of positive electrode sheets 11 on the negative electrode sheet 14 is such that one end 12 b of the plurality of positive electrode current collector foils 12 protrudes from one end 15 b of the band-shaped negative electrode current collector foil 15, Each of the positive electrode sheets 11 corresponds to a fold of the negative electrode sheet 14 so that the other end 15a of the negative electrode current collector foil 15 projects from the other end 12a of the plurality of positive electrode current collector foils 12. It is arranged with a part opened.

As shown in FIG. 6, the folding of the negative electrode sheet 14 on which the positive electrode sheet 11 is laminated is performed by alternately folding the folds of the negative electrode sheet 14 on which the positive electrode sheet 11 is not arranged. . When folded like this,
As shown in FIG. 5, the negative electrode sheet 1 thus folded
A plurality of positive electrode sheets 11 each having an area corresponding to the folded area are sandwiched between the polymer electrolyte layers 17 except for the fourth fold. Then, as shown in FIG. 4, one end 12b of the plurality of positive electrode current collector foils 12 protrudes from one end 15b of the band-shaped negative electrode current collector foil 15, and The other end 15a is a plurality of positive electrode current collector foils 1
2 are protruded from the other end 12a.

As shown in FIGS. 1, 4 and 6, all one end portions 12b of the plurality of positive electrode current collector foils 12 are laminated, and one end of a sheet-like positive electrode terminal 23 is connected to the plurality of positive electrode current collector foils. It is inserted between all the one end portions 12b of the body foil 12 that are stacked. In the inserted state, one end of the positive electrode terminal 23 is connected to one of the plurality of positive electrode current collector foils 12 by a plurality of burrs 25 which are caulked at predetermined intervals t (FIG. 1) in a direction intersecting the insertion direction. Is connected to the end 12b. on the other hand,
All the other ends 15a of the plurality of negative electrode current collector foils 15 are laminated, and one end of the sheet-shaped negative electrode terminal 21 is located between all the other ends 15a of the plurality of negative electrode current collector foils 15 laminated. Is inserted into. In the inserted state, one end of the negative electrode terminal 21 is connected to the other of the plurality of negative electrode current collector foils 15 by a plurality of burrs 25 which are caulked at predetermined intervals t (FIG. 1) in a direction intersecting the insertion direction. To the end 15a. A flexible expanded metal or a perforated metal sheet is used for each of the positive electrode terminal 23 and the negative electrode terminal 21 in this embodiment.

More specifically, as shown in FIG.
The eyelet 25 has a cylindrical portion 25a and a fixed flange 25c formed continuously at one end of the cylindrical portion 25a. On the other hand, the other end 15a of the plurality of negative electrode current collector foils 15 with one end of the negative electrode terminal 21 interposed therebetween has:
A reinforcing foil or a reinforcing thin plate 22 made of the same material as the material of the negative electrode current collector foil 15 and having a thickness of 0.05 to 0.5 mm.
Are arranged on the outer surface of the laminate. Then, the other end 15a where the reinforcing foil or the reinforcing thin plate 22 and the negative electrode current collector foil 15 are stacked and one end of the negative electrode terminal 21 are provided as shown in FIG.
As shown in FIG. 1, a predetermined interval t (FIG. 1) in a direction intersecting the insertion direction of one end of the negative electrode terminal 21 in a state where they are stacked is shown.
A plurality of through holes 27 are formed. As shown in FIG. 3B, the cylindrical portion 25a of the ferrule 25 is inserted into the through hole 27 until the fixing flange 25b contacts the hole edge. Then, the other end of the cylindrical portion 25a penetrates the through hole 27 and protrudes from the reinforcing foil or the reinforcing thin plate 22.

When the end of the punch 28 is pressed into the other end of the protruding cylindrical portion 25a, the end is mechanically pushed open, and the claw 25c shown in FIG.
To form In this embodiment, a notch 25d is formed at the other end of the cylindrical portion 25a so that the end is split into eight portions when the cylindrical portion 25a is expanded. As shown in FIG. 8 nails 25c when unfolded
Are configured to form a radius. Returning to FIG. 3 (c), the eight radial claws 25c abut against the other edge of the through hole 27, and the other end 15a of the negative electrode current collector foil 15 laminated with the fixing flange 25a is reinforced with a reinforcing foil. Alternatively, it is sandwiched together with the reinforcing thin plate 22 and one end of the negative electrode terminal 21. Thereby, one end of the negative electrode terminal 21 is connected to the plurality of negative electrode current collector foils 15.
Are connected to all the other ends 15a.

As shown in FIGS. 1 and 4, the outer surface of the laminated one end 12b of the positive electrode current collector foil 12 is made of Al which is the same material as the material of the positive electrode current collector foil 12. Reinforcing foils or reinforcing thin plates 24 each having a thickness of 0.05 to 0.5 mm are arranged. And a reinforcing foil or a reinforcing thin plate 2
4. One end 12b of the laminated positive electrode current collector foil 12 and one end of the positive electrode terminal 23 have a predetermined interval t in a direction intersecting the insertion direction of one end of the positive electrode terminal 23 in a state where they are laminated. A plurality of through holes (not shown) are formed by opening (FIG. 1). The above-mentioned ferrule 25 is inserted into this through-hole and swaged, and one end of the positive electrode terminal 23 is connected to one end 12 b of all the plurality of positive electrode current collector foils 12. In addition,
Reinforcing foils or thin reinforcing plates 22, 24 arranged on the outer surface of the laminate
Is formed so as to have an area larger than the area covered by the crimped claw 25c of the diaper 25, so that an excessive load is not applied to each of the positive electrode current collector foil 12 and the negative electrode current collector foil 15 at the time of caulking. To be. The value obtained by dividing the outer diameter d (FIG. 2) of the claws 25c radially spread by a predetermined interval t is adjusted to be in the range of 0.2 to 1.8, and under the most appropriate condition. The positive electrode terminal 23 and the negative electrode terminal 21 are joined.

As shown in FIG. 4 and FIG. 5, the band-shaped negative electrode sheet 14 thus folded
Together with the package sheet 26. As the package sheet 26 in this embodiment, an aluminum foil laminated with modified polypropylene is used.
A band-shaped negative electrode sheet 14 folded by a pair of package sheets 26 so that the laminated modified polypropylene faces each other is sandwiched together with a plurality of positive electrode sheets 11,
The band-shaped negative electrode sheet 14 folded by heat-bonding the denatured polypropylenes to each other by thermocompression bonding around the stacked package sheets 26 in a vacuum atmosphere is sealed together with the plurality of positive electrode sheets 14 by the package sheet 26. .

At the time of sealing, the pair of package sheets 26 sandwich the positive terminal 23 and the negative terminal 21 so that the other end of the positive terminal 23 and the other end of the negative terminal 21 are exposed outside the package sheet 26, respectively. In this state, the periphery of the pair of package sheets 26 is thermocompression-bonded. In this embodiment, since the positive electrode terminal 23 and the negative electrode terminal 21 are each formed of an expanded metal or a perforated metal sheet, when the periphery of the package sheet 26 is thermocompression-bonded, modified polypropylene laminated on an aluminum foil is used. Is melted by heat and penetrates into the stitches of the expanded metal or the perforations of the metal sheet, and then the modified polypropylene is hardened, so that the adhesion between the package 26 and the positive electrode terminal 23 and the negative electrode terminal 21 is ensured, and the secondary The battery is securely sealed.

In the lithium ion polymer secondary battery 10 thus configured, desired electricity can be obtained by using the other ends of the positive and negative terminals 21 and 23 drawn from the package sheet 26 as the terminals of the battery. Can be. Here, all the one end portions 12b of the plurality of positive electrode current collector foils 12 and all the other end portions 15a of the plurality of negative electrode current collector foils 15 are laminated to form a positive electrode terminal 23 and a negative electrode terminal 21, respectively. Although the connection is made, the connection is performed by a plurality of staples 25 caulked at a predetermined interval t,
An increase in mechanical strength can be suppressed as compared with a case where all of the stacked end portions are joined, and the flexibility that the sheet-shaped secondary battery 10 has conventionally can be secured.

One end of the positive electrode terminal 23 is inserted between all the one end portions 12b of the plurality of the positive electrode current collector foils 12 laminated, and one end of the negative electrode terminal 21 is connected to the plurality of the negative electrode current collector foils 1.
5 is inserted between all the other end portions 15a of the stack, so that even if the secondary battery 10 is repeatedly bent, the positive electrode terminal 23 and the positive electrode current collector foil 12 sandwiching the positive electrode terminal 23 are interposed. Alternatively, there is no gap between the negative electrode terminal 21 and the negative electrode current collector foil 15 sandwiching the negative electrode terminal 21, the conductivity at the contact portion is ensured, and the resistance at the terminal junction can be sufficiently reduced. it can. Further, the positive electrode current collector foil 1
2, a reinforcing foil or a reinforcing thin plate 24 is disposed on the outer surface of the laminated one end 12b, and the reinforcing foil or the reinforcing thin plate 2 is disposed on the outer surface of the laminated other end 15a of the negative electrode current collector foil 15.
2 is arranged, so that when the secondary battery 10 is curved,
It is possible to prevent breakage such as a crack in the caulked portion of the positive electrode current collector foil 12 and the negative electrode current collector foil 15 on the outside, and improve the reliability of the secondary battery 10.

In the above-described embodiment, the strip-shaped negative electrode sheet 14 in which a plurality of positive electrode sheets 11 are thermocompression-bonded at a predetermined pitch is alternately bent at a fold where the positive electrode sheet 11 is not arranged. A plurality of anode sheets having the same shape and size as the cathode sheet are prepared in the same number as the cathode sheet, a polymer electrolyte layer is interposed between the cathode active material and the anode active material, and a plurality of cathodes constituting the sheets are provided. It may be a laminate of a current collector foil and a plurality of negative electrode current collector foils.

[0028]

Next, embodiments of the present invention will be described. Example 1 First, a plurality of positive electrode sheets 11 were produced.
That is, 70 g of LiCoO ₂ powder and 4 g of graphite powder (trade name: Ketjen Black) are mixed with N of polyvinylidene fluoride.
-Methylpyrrolidone solution was dispersed and mixed to prepare a slurry. On the other hand, a vinylidene fluoride-hexafluoropropylene copolymer (manufactured by Elphatochem, Kynar 281)
0; product containing 12% by weight of hexafluoropropylene) 40
g in 200 g of dimethyl carbonate at 60 ° C.
Further, 80 g of the electrolyte solution was stirred and mixed to prepare an electrolyte slurry. Next, on the upper surface of an Al foil having a width of 10 cm and a length of 1 m,
The slurry obtained by dispersing and mixing the active material was applied and dried by a doctor blade method, and the electrolyte slurry was applied and dried so as to cover the positive electrode active material 13. The strip-shaped Al foil on which the positive electrode active material 13 and the polymer electrolyte layer 17 are formed by drying is used for the positive electrode active material 13 and the polymer electrolyte layer 1.
Cut with 10 and 10cm in width and 10cm in length
One positive electrode sheet 11 was obtained.

Next, a strip-shaped negative electrode sheet 14 was prepared. That is, a slurry obtained by dispersing and mixing 50 g of flaky natural graphite powder in an N-methylpyrrolidone solution of polyvinylidene fluoride was applied to the upper surface of a Cu foil having a width of 10 cm and a length of 1 m by a doctor blade method and dried, followed by the above-described procedure. The electrolyte slurry was further applied so as to cover the positive electrode active material 13 and dried to prepare a strip-shaped negative electrode sheet 14. A plurality of positive electrode sheets 11 are thermocompression-bonded to the belt-shaped negative electrode sheet 14 at a predetermined pitch corresponding to the interval between the folds, and the folds of the negative electrode sheet 14 on which the positive electrode sheet 11 is not arranged are alternately bent to have a width of 10 cm. Each of the widths 1 between the polymer electrolyte layers 17 of the strip-shaped negative electrode sheet 14 having a folding area of 10 cm in length.
A laminate in which ten positive electrode sheets 11 each having a length of 0 cm and a length of 10 cm were sandwiched was obtained.

All the one end portions 12b of the plurality of positive electrode current collector foils 12 protruding from one end portion 15b of the negative electrode current collector foil 15 of this laminate are laminated, and nickel-plated to a thickness of 0.1 mm. One end of a sheet-like positive electrode terminal 23 made of expanded metal knitted by the formed copper wire is inserted between one of the stacked end portions 12b, and 10 mm in a direction intersecting the insertion direction in the inserted state. Nine through-holes are formed at intervals, and staples 25 are inserted into the through-holes and swaged to form the positive electrode current collector foil 12 with the nine staples 25 at which one end of the positive electrode terminal 23 is swaged. Are connected to all the one ends 12b. In addition, the positive and negative electrode current collector foils 12
Negative electrode current collector foils 1 protruding from the other end 12a of the
5 are laminated, and the thickness is 0.1 mm.
One end of a sheet-shaped negative electrode terminal 21 made of expanded metal woven by nickel-plated copper wire is inserted between the other end 15a of the sheet, and a direction intersecting the insertion direction in the inserted state. Nine through-holes are formed at intervals of 10 mm, and a plurality of negative electrodes are formed by the nine holes 25 in which one end of the negative electrode terminal 21 is swaged by inserting a swage 25 into the through-hole and swaging. The collector foil 15 was connected to all the other ends 15a. Then the positive terminal 2
3 and the other end of the negative electrode terminal 21 were hermetically sealed with a package 26 so that a lithium ion polymer secondary battery was obtained. This battery was designated as Example 1.

Comparative Example 1 The same laminate as in Example 1 was obtained in the same procedure as in Example 1. All the one end portions 12b of the plurality of positive electrode current collector foils 12 protruding from one end portion 15b of the negative electrode current collector foil 15 of this laminate are laminated, and the same expanded metal as in Example 1 is used. One end portion 12b of the laminated positive electrode terminal is sandwiched between the pair of positive electrode terminals, and in this state, two through holes are formed at an interval of 80 mm together with the pair of positive electrode terminals. By inserting and caulking, one end of the positive electrode terminal 23 was connected to all one end portions 12b of the plurality of positive electrode current collector foils 12 by two caulks 25 which were caulked. Further, all the other end portions 15a of the plurality of negative electrode current collector foils 15 protruding from the other end portions 12a of the positive and negative electrode current collector foils 12 of the laminate are laminated, and the same expanded end as in the first embodiment is used. One end 12 laminated by a pair of negative electrodes made of metal
b, and in this state, together with a pair of negative electrode terminals, 80 m
The two holes are formed at intervals of m, and the stopper 25 is inserted into the through holes and swaged to form the negative electrode terminal 21.
Are connected to all one end portions 15a of the plurality of negative electrode current collector foils 15 by two crimping staples 25.
Thereafter, the package was sealed with a package 26 so that the other end of the positive electrode terminal 23 and the other end of the negative electrode terminal 21 were exposed, to obtain a lithium ion polymer secondary battery. This battery was designated as Comparative Example 1.

<Comparative Test> The lithium ion polymer secondary batteries of Example 1 and Comparative Example 1 were curved until the radius of curvature became 15 cm, and then curved in the opposite direction until the radius of curvature became 15 cm, and this was repeated 10 times. Later, each 3
A discharged. At this time, the ratio to the capacity at the time of discharging at 0.5 A was measured. As a result, in Example 1, 80% of the discharge capacity was secured, but in Comparative Example 1, it was 30%. <Evaluation> It is understood that the discharge capacity of Comparative Example 1 is lower than that of Example 1. This is because the terminals in Comparative Example 1 are arranged so as to sandwich the ends of the laminated positive electrode current collector foil and negative electrode current collector foil, and in this state, the battery is bent because the crimping is performed. It is considered that a gap was formed between the end of the current collector foil other than the swaged portion and the terminal, and the conductivity at that portion was lost. On the other hand, it can be seen that Example 1 has a higher discharge capacity than Comparative Example 1. This is inserted between the ends of the bundled positive electrode current collector foil and negative electrode current collector foil in which the terminals in Example 1 are stacked, and the inserted state is crimped, so that the battery is bent. There is no gap between the end of the current collector foil and the terminal, and the reason is considered to be that the conductivity between the end of the current collector foil and the terminal is sufficiently ensured. Can be

[0033]

As described above, according to the present invention, all one ends of the plurality of positive electrode current collector foils and all the other ends of the plurality of negative electrode current collector foils are laminated. One end of the positive electrode terminal is connected to the end of the plurality of positive electrode current collector foils by a plurality of crimps caulked at a predetermined interval, and the plurality of crimps caulked at a predetermined interval to a negative electrode terminal. Was connected to the other end of the plurality of negative electrode current collector foils,
An increase in mechanical strength can be suppressed as compared with a case where all of the stacked end portions are joined, and the flexibility that a sheet-shaped secondary battery has conventionally can be secured. In addition, one end of the positive electrode terminal is inserted between all the one ends of the plurality of positive electrode current collector foils stacked, and one end of the negative electrode terminal is connected to the other of all the plurality of negative electrode current collector foils stacked. Because it was inserted between the ends, even if the secondary battery was repeatedly bent, between the positive electrode terminal and the positive electrode current collector foil sandwiching the positive electrode terminal, or between the negative electrode terminal and the negative electrode current collector foil sandwiching the negative electrode terminal There is no gap between them, the conductivity at the contact portion is ensured, and the resistance at the terminal junction can be sufficiently reduced.

When an expanded metal or a perforated metal sheet is used as the positive electrode terminal and the negative electrode terminal, respectively, the flexibility of the terminal itself is ensured and the flexibility of the sheet-shaped secondary battery is ensured. It is possible to secure the secondary battery by bending the reinforcing foil or the reinforcing thin plate on the outer surface of the laminate at one end of one or both of the positive electrode current collector foil and the negative electrode current collector foil. In such a case, it is possible to prevent breakage such as a crack in a swaged portion of the positive electrode current collector foil and the negative electrode current collector foil on the outside, and it is also possible to improve the reliability of the secondary battery.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a secondary battery of the present invention.

FIG. 2 is a view C of FIG.
Arrow view.

FIG. 3 is a sectional view showing a procedure for swaging the staple.

FIG. 4 is a sectional view taken along the line BB of FIG. 5 showing the secondary battery.

FIG. 5 is a sectional view taken along line AA of FIG. 4 showing the secondary battery.

FIG. 6 is an exploded perspective view showing the configuration of the secondary battery.

FIG. 7 is a perspective view showing a state in which a positive electrode sheet is thermocompression-bonded to the negative electrode sheet.

FIG. 8 is a view showing a manufacturing process of the positive electrode sheet.

FIG. 9 is a view showing a manufacturing process of the negative electrode sheet.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Lithium ion polymer secondary battery 12 Positive electrode collector foil 12a The other end 12b One end 13 Positive electrode active material 15 Negative current collector foil 15a The other end 15b One end 16 Negative electrode active material 17 Polymer electrolyte Layer 21 Negative electrode terminal 22 Reinforcement foil or thin sheet 23 Positive electrode terminal 24 Reinforcement foil or thin sheet 25 Stopper 25a Claw t Predetermined interval d Outer diameter of claw

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Akio Mizuguchi 1-297 Kitabukurocho, Omiya City, Saitama Prefecture Within Mitsubishi Materials Research Institute (72) Inventor Akihiro Higami 1-297 Kitabukurocho, Omiya City, Saitama Mitsubishi Materials F-term in the Research Institute Co., Ltd. (reference)

Claims (5)

[Claims] A positive electrode active material (13) is applied to each surface of a plurality of positive electrode current collector foils (12), and a negative electrode active material (16) is applied to each surface of a plurality of negative electrode current collector foils (15). Coated, the plurality of positive electrode current collector foils (12) and the plurality of negative electrode current collector foils (15) are each a polymer electrolyte between the positive electrode active material (13) and the negative electrode active material (16). Laminated through a layer (17), the negative electrode current collector foil (15)
A sheet-like positive electrode terminal is provided on all one ends (12b) of the plurality of positive electrode current collector foils (12) projecting from one end (15b) of the
One end of (23) is connected, and all other ends (15a) of the plurality of negative electrode current collector foils (15) projecting from the other end (12a) of the positive electrode current collector foil (12) One end of a sheet-shaped negative electrode terminal (21) is connected to the positive electrode current collector foil (12) so that the other end of the positive electrode terminal (23) and the other end of the negative electrode terminal (21) are exposed. In a lithium ion polymer secondary battery in which a laminate with the negative electrode current collector foil (15) is sealed by a package (26), one end of all of the plurality of positive electrode current collector foils (12) (12b )
And all the other ends (1) of the plurality of negative electrode current collector foils (15).
5a) are laminated, and one end of the positive electrode terminal (23) is connected to the plurality of positive electrode current collector foils (12).
A predetermined interval (t) inserted between all the one end portions (12b) of the stack and in a direction intersecting the insertion direction in the inserted state.
One end of the positive electrode terminal (23) is connected to one end (12b) of all of the plurality of positive electrode current collector foils (12) by a plurality of crimps (25) which are One end of the terminal (21) is a plurality of the negative electrode current collector foil (15)
A predetermined interval (t) inserted between all the other end portions (15a) of the stack and in a direction intersecting the insertion direction in the inserted state.
One end of the negative electrode terminal (21) is connected to all the other ends (15a) of the plurality of negative electrode current collector foils (15) by a plurality of staples (25) which are opened and crimped. Characteristic lithium ion polymer secondary battery. 2. The lithium ion polymer secondary battery according to claim 1, wherein each of the positive electrode terminal (23) and the negative electrode terminal (21) is an expanded metal or a perforated metal sheet. 3. The same material as the material of the positive electrode current collector foil (12) or the material of the negative electrode current collector foil (15), and is 0.05 to 0.5 mm.
A reinforcing foil or a reinforcing thin plate having a thickness of (22, 24) is disposed on the laminated outer surface of one or both ends of the positive electrode current collector foil (12) or the negative electrode current collector foil (15). 3. The lithium ion polymer secondary battery according to claim 1, wherein a plurality of claws (25) are respectively caulked via the reinforcing foil or the reinforcing thin plate (22, 24). 4. The lithium-ion polymer secondary battery according to claim 1, wherein the number of claws (25c) of the caulked staple (25) is 5 to 15. 5. The value obtained by dividing the outer diameter (d) of the claw (25c) of the swaged diaper (25) by a predetermined interval (t) is 0.2 to 1.8. The lithium ion polymer secondary battery according to any one of the above.