JP3511709B2 - Thin battery - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improvement of load characteristics and cycle characteristics of thin batteries.

[0002]

2. Description of the Related Art In recent years, cordless devices such as mobile phones, camcorders, and notebook personal computers have been remarkably reduced in size, weight, and thickness. There is a growing demand for thin and flat products, from the viewpoints of thinning equipment and effective use of space.

The prismatic nickel-cadmium battery and the prismatic nickel-hydrogen battery which have been conventionally used as this thin battery form an electrode plate group by forming a positive electrode and a negative electrode of a single plate (flat plate) with a separator interposed therebetween to form a laminated structure. ing. However, in the equipment used, large current and high voltage are required, and in consideration of higher output and improvement of high load characteristics, the electrode plates are thinned to increase the number of them and increase the effective reaction area. It is effective to lower the current density by using a spirally wound thin electrode plate as a spiral electrode plate group, and it is also advantageous in terms of productivity. .

In order to insert such a spiral electrode group into a thin battery, it is necessary to construct the spiral electrode group so that its sectional shape is an ellipse.

As a method for constructing the spiral electrode plate group so that the cross-sectional shape becomes an ellipse, (1) a method in which the electrode plate is wound around a flat plate-shaped winding core (JP-A-6-96801). ), (2) A method of forming a spiral or elliptical spiral electrode plate group by compressing it in a predetermined direction (JP-A-6-
96802), and (3) a method of forming a spiral electrode plate group constituted by a winding core in which three or more rods are combined in parallel by compressing in a predetermined direction (JP-A-6-150972). ing.

[0006]

However, in the above method (1), as shown in FIG. 5, in the plane portion of the spiral electrode plate group, the force is applied in the direction perpendicular to the winding direction of the electrode plate group. Since the way of hanging is weak, the adhesion between the electrode plates becomes insufficient, and as shown by the hatched part in the figure, the distance between the electrode plates varies, which adversely affects the charge / discharge characteristics and cycle characteristics. .

Further, in the methods (2) and (3), as shown in FIG. 6, since the shape once formed into a circular shape or the like is compressed and formed, the space between the electrode plates is compressed during the compression. As the contact state is released and the electrode plate on the inner circumference shows irregular deformation, the distance between the electrode plates becomes large, especially in the flat part, as shown by the hatched portion in the figure, and the charge-discharge characteristics And the cycle characteristics were adversely affected.

Further, in any of the methods (1), (2), and (3), when the electrode plate group is inserted into the battery case in the battery assembly process, the resistance between the case inner surface and the electrode plate group outer periphery is increased. Depending on the case, the electrode plate group may not be inserted evenly,
As shown in FIG. 7, a deviation occurs in the height direction between the electrode plates,
In an extreme case, the positions of the positive electrode plate and the negative electrode plate may be reversed at the ends, which may adversely affect charge / discharge characteristics, cycle characteristics, and safety. Moreover, there is a possibility that the same state may be caused by dropping the battery.

The present invention solves the above problems,
Prevents battery performance deterioration caused by non-uniformity of the degree of tightness between the plates or displacement in the height direction between the plates, resulting in high performance,
The purpose is to provide a high quality battery.

[0010]

According to the present invention, a positive electrode plate, a negative electrode plate, and a separator are wound in a spiral shape to have a cross-sectional shape of an electrode plate group.
A thin electrode that is composed of a flat surface and a curved surface in an oval shape.
In the pond, the bondage material said electrode plate group are wound in a spiral direction perpendicular to the direction of the electrode plate group, the upper and lower end face of the electrode plate group
And a thin battery fixed by a flat portion connected to the thin battery .

The spirally wound electrode plate group is formed by winding an electrode plate around a flat core material, and a circular spirally wound electrode plate group.
It may be formed by compressing the elliptical spiral electrode group or the rhomboid spiral electrode group in a predetermined direction.

[0012]

According to the present invention, whether the cross-sectional shape is a flat surface portion or a curved surface portion.
The electrode plate group consisting of an ellipse consisting of the electrode plate group is wound by the binding material wound in the direction perpendicular to the spiral direction of the electrode plate group.
It is fixed at the upper and lower end faces and the flat part connected to this
Therefore , the flat part of the spiral electrode plate group is pressed in the thickness direction,
It is possible to correct the variation in the distance between the electrode plates and the irregular deformation of the electrode plates.

Further, since the height direction of the spiral electrode plate group is fixed, it is possible to prevent the electrode plates from being displaced when the electrode plate group is inserted into the case or the battery is dropped.

Therefore, since the degree of tightness of the electrode plate group can be kept uniform and the position of the electrode plate can also be kept constant, not only the discharge characteristic and the cycle characteristic in the case of a secondary battery are improved. , Safety is also improved.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 schematically shows a cross section of a battery having a spiral electrode plate group of this embodiment. The binding material 1 is formed by winding the plane portion of the spiral electrode plate group in a direction perpendicular to the spiral direction, and the spiral electrode plate group 2
Is obtained by winding the positive electrode 3, the negative electrode 4, and the separator 5 located between these two electrode plates. The spiral electrode plate group 2 is inserted into the battery case 6 having conductivity. Battery case 6
And the negative electrode lead 7 are connected via a bridge plate 11,
The positive electrode lead 8 is connected to the sealing plate 9. Then, after injecting the electrolytic solution, the sealing plate 9 is caulked with the open end of the battery case 6 through the insulating packing 10 to seal the battery.

In the embodiment, the negative electrode lead 7 is connected to the bridging plate 1.
1 is connected to the battery case 6 through the bridge plate 11
The negative electrode lead 7 and the battery case 6 may be directly connected without using.

Although the sealing plate 9 caulks and seals the open end of the battery case 6 via the insulating packing 10, the periphery of the sealing plate 9 and the positive electrode terminal are insulated from each other, and the sealing plate 9 and the battery case 6 are insulated. The open end of may be laser welded.

FIG. 2 is a front view and a top view of the spiral electrode group of this embodiment. Lithium cobalt oxide as the positive electrode active material,
Carbon is used as the negative electrode active material, a porous polypropylene sheet is used as the separator, ethylene carbonate and diethylene carbonate are mixed as the electrolytic solution, and a secondary battery is formed by using an organic electrolytic solution in which 1 mol / l of lithium hexafluorophosphate is dissolved. Configured. The size of this battery is 8 mm thick and 40 m wide.
m, height 48 mm.

The positive electrode 3, the negative electrode 4, and the separator 5 are spirally wound around a flat plate as shown in FIG. 3 using the above-mentioned material to form an elliptical shape, which is then perpendicular to the spiral direction of the flat surface of the electrode plate group. Direction using polypropylene tape as binding material 1
A battery having an electrode plate group wound on the upper and lower end surface portions of the electrode plate group and a flat portion connected to the electrode plate group is referred to as a battery A of the present embodiment.

Further, using the same material, a positive electrode 3, a negative electrode 4, and a separator 5 as shown in FIG. using polypropylene tape as bondage material 1 in the spiral direction perpendicular to the direction of the plate group, the upper and lower end face of the electrode plate group and communicating thereto
A battery having an electrode plate group wound on the flat surface is referred to as battery B of this example.

As comparative examples, batteries C and D were prepared which were similar except that the binding materials of batteries A and B were not used.

[Load Characteristics] The load characteristics of the batteries A and B and the batteries C and D were measured, and the results are shown in FIG. The measurement condition is that each battery has a charging current of 170 mA and an end-of-charge voltage of 4.1.
After charging to V, the battery is discharged to a discharge end voltage of 3 V with a discharge current of 850 mA.

From FIG. 5, the batteries A and B are the batteries C and D.
It can be seen that the battery voltage is high and the discharge time is long as compared with.

[Cycle characteristics] Battery A, B and battery C,
The cycle characteristics of D were measured, and the results are shown in FIG.
The measurement conditions are such that each battery is repeatedly charged with a charging current of 170 mA to a final charging voltage of 4.1 V and then discharged with a discharging current of 850 mA to a final discharging voltage of 3 V.

From FIG. 6, the batteries A and B are the batteries C and D.
It can be seen that the battery voltage is high, the cycle life is long, and the capacity retention rate is long, compared with.

[Reliability] Table 1 shows the number of occurrences of displacement of the electrode plates during the drop test of the batteries A and B and the batteries C and D.

[0028]

[Table 1]

The test condition is that each battery is erected and dropped three times from a height of 75 cm on concrete, and then the displacement of the electrode plate is inspected using an X-ray fluoroscope.

From Table 1, it is understood that the batteries A and B have better positional stability of the electrode plates than the batteries C and D.

[0031] From the above results, the battery A, B is the upper and lower ends face and a plane portion continuous thereto electrode plate group by bondage material spiral direction perpendicular to the direction of the cross section oval spiral electrode group
Since it is wound around, the contact between the electrode plates is always maintained.
Further, the position of the electrode plate in the height direction is stable, and the cycle characteristics and reliability are improved.

In this embodiment, a polypropylene tape is used as the electrode plate binding material, but any tape or heat shrinkable tube that is stable to the electrolytic solution may be used. Specifically, the same effect was obtained by using a tape made of polyethylene or polyflon and a shrink tube made of polypropylene, polyethylene, polyflon or a tape made of metal foil.

[0033]

According to the present invention, whether the sectional shape is a flat surface portion or a curved surface portion.
Upper and lower end face portion of the electrode plate group by bondage material vortex winding direction at right angles with the direction of Ranaru oblong spiral electrode group and flat continuous thereto
Since it is wound on the surface , the adhesion between the plates is always kept uniform, and the position of the plates in the height direction is stable, resulting in load characteristics, cycle characteristics and reliability. It is possible to improve.

[Brief description of drawings]

FIG. 1 is a sectional view of a battery according to an embodiment of the present invention.

FIG. 2 is an external view of a spiral electrode plate group used in a battery according to an embodiment of the present invention.

FIG. 3 is a sectional view of a spiral electrode plate group used in a battery according to an embodiment of the present invention.

FIG. 4 is a sectional view of a spiral electrode plate group used in a battery according to an embodiment of the present invention.

FIG. 5 is a diagram showing load characteristics of batteries A, B, C and D.

FIG. 6 is a diagram showing cycle characteristics of batteries A, B, C and D.

FIG. 7 is a top view of a conventional spiral electrode plate group using a flat plate-shaped winding core.

FIG. 8 is a top view of a spiral electrode plate group obtained by compressing a conventional circular or elliptical structure.

FIG. 9 is a cross-sectional view showing a state where the electrode plates are displaced from each other on the end surface of the conventional spiral electrode plate group.

[Explanation of symbols] 1 binding material 2 spiral plate group 3 Positive plate 4 Negative plate 5 separator 6 battery case 7 Negative electrode lead 8 Positive lead 9 Seal plate 10 Insulating packing 11 bridge plate

Front page continued (72) Inventor Satoshi Miura 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Inventor, Yukimasa Niwa 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd. (72 ) Inventor Toru Takai 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) Reference JP-A-6-215793 (JP, A) JP-A-6-150971 (JP, A) JP-A 62-256384 (JP, A) JP-A-57-163965 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01M 6/02 H01M 10/04 H01M 10/38 H01M 10 / 40

Claims (3)

(57) [Claims] 1. A thin battery sectional shape of the positive electrode plate and the negative electrode plate and the electrode group formed by winding a separator spirally is configured oval consisting plane portion and a curved portion, the electrode plate group is extremely
In bondage material is wound in a spiral direction perpendicular to the direction of the plate group
On the upper and lower end face parts of the electrode plate group and the flat part connected to this.
Thin battery that is fixed in place. 2. The thin battery according to claim 1, wherein the electrode plate group is wound around a flat plate-shaped core material. Wherein the The electrode assembly may be configured to compress the perfect circular spiral plate group, elliptical spiral electrode group and a rhombus spiral electrode group
Thin battery according to claim 1, wherein there.