JP2002117900A - Coin form battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coin form battery, which attained equalization of a rate of tension, which joins a pole plates group when constituting the coin form battery using the pole plates group of a winding structure. SOLUTION: A positive pole lead 15 made to take out from the end of the positive pole plate, and a negative pole lead 16 made to take out from the end of the negative pole plate are formed in a position, which biased toward the opposite direction mutually. When winding the positive pole plate and the negative pole through a separator forms the pole plates group 1a, the positive pole lead 15 and the negative pole lead 16 are ridden in different positions. Thereby, a difference of a thickness distribution of the pole plates group 1a is controlled. Then, when it is accommodated in the inside of a seal case 5 and a battery case 4, which are sealed, a big difference does not arise to the rate of tension added to the pole plates group 1a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coin-shaped battery formed in a flat cylindrical shape, and more particularly to a coin-shaped battery case having a wound electrode group so as to obtain high load discharge characteristics. The present invention relates to a coin-shaped battery housed in a battery.

[0002]

2. Description of the Related Art A coin-type battery, which is also called a button-type battery or a flat-type battery, is small and thin.
It is widely used when thinning is required such as a card.

[0003] As shown in FIG.
A positive electrode pellet 32 and a negative electrode pellet 33 formed in a disk shape are placed in an internal space in which a battery case 31 and a sealing case 35 formed in a circular half-shell body are arranged with openings facing each other.
Are disposed to face each other with a separator 34 interposed therebetween, and an electrolyte is injected. The battery case 31 and the sealing case 35 are joined together to seal the internal space. The battery case 31 is provided outside the sealing case 35 in which the gasket 36 is mounted.
And the battery case 31 is closed by caulking to bend the open end of the battery case 31 inward to form a battery having a coin-shaped appearance.

[0004]

In such a coin-type battery structure in which the positive electrode pellet 32 and the negative electrode pellet 33 face each other at a ratio of 1: 1, the reaction area where the positive electrode plate and the negative electrode plate face each other is small. Due to such factors, the continuous discharge current is at most about 10 mA, and there is a problem that it can be applied only to a device having a small load current.

In order to extract a large discharge current, it is necessary to increase the counter electrode area between the positive electrode plate and the negative electrode plate.
In batteries other than coin-type batteries, a laminated structure in which a plurality of positive electrode plates and negative electrode plates are laminated with a separator interposed therebetween, or a separator arranged between a strip-shaped positive electrode plate and a negative electrode plate in a spiral shape A structure for increasing a reaction area by a wound structure is widely used. If such a laminated or wound electrode plate can be accommodated in a flat case having a small height such as a coin-shaped battery, a flat battery with an increased discharge current is realized. be able to.
The battery realizing this was previously proposed by the present applicant,
The one disclosed in 000-164259 is known.

However, the battery disclosed herein is a case where the planar shape is rectangular, and the thin rectangular parallelepiped electrode group is accommodated in a rectangular parallelepiped battery case by a wound structure or a laminated structure, so that the volume efficiency is reduced. A good battery can be formed, but when applied to a coin-shaped battery having a circular planar shape, a rectangular electrode plate is housed in a circular battery case, and the volume efficiency is low and a sufficient battery capacity cannot be obtained. was there.

An object of the present invention is to increase the discharge capacity by accommodating a wound electrode plate in a thin cylindrical volume such as a coin-type battery, and to increase the battery case and the positive electrode plate. An object of the present invention is to provide a coin-type battery in which electrical connection between a sealing case and a negative electrode plate is ensured.

[0008]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the present invention provides an electrode plate formed by flatly winding a strip-shaped positive electrode plate and a negative electrode plate with a separator interposed therebetween. A coin-shaped battery that is housed in an internal space in which a battery case and a sealing case formed in a shell are coupled with their openings facing each other, wherein the electrode group includes one end of a positive electrode plate. A positive electrode lead is formed at a position biased to one side in the width direction of
A negative electrode lead is formed at a position deviated in a direction opposite to the positive electrode lead extension position in the width direction on one end side of the negative electrode plate, and the one end side on which the positive electrode lead and the negative electrode lead are formed ends at the end of winding. And the negative electrode plate is wound with a winding width smaller than the diameter of the circular housing space of the internal space, and a positive electrode lead is provided on the battery case in a space vacated on both sides in the winding direction of the electrode plate group. The lead is welded to the sealing case.

According to the above configuration, the positive electrode lead and the negative electrode lead are formed so as to extend from one end of each of the positive electrode plate and the negative electrode plate in a direction deviated in the opposite direction to each other. Sometimes they are placed on the electrode group at different positions,
A large difference does not occur in the distribution of the tension rate applied to the electrode plate group when housed between the battery case and the sealing case, and a state in which the positive electrode plate and the negative electrode plate face each other evenly is obtained.

[0010] The electrode group in the above configuration is obtained by winding a positive electrode plate, a negative electrode plate, and a separator having a fixed width into a rectangular planar shape having a longer side in the width direction, and then the rectangular corners are formed by straight lines or arcs. The cut configuration, or the positive electrode plate and the negative electrode plate are formed in a band shape in which a circular or polygonal laminated surface is connected by a connecting piece of a predetermined width, and the laminated surface of the positive electrode plate and the laminated surface of the negative electrode plate are formed. It is possible to apply a configuration in which the connection piece is folded flat and wound flat so as to be stacked via a separator,
The electrode group can be configured as a space-efficient electrode group with respect to the circular housing space, and in combination with the wound structure, a coin-type battery having high load current characteristics is configured.

[0011]

Embodiments of the present invention will be described below with reference to the accompanying drawings to provide an understanding of the present invention.
The embodiment described below is an example embodying the present invention, and does not limit the technical scope of the present invention.

The coin-shaped battery according to the present embodiment is an example in which the coin-shaped battery is configured as a lithium ion secondary battery. The coin-shaped battery according to the embodiment is, as shown in a sectional view in FIG. The gasket 6 is attached to the side peripheral surface of the sealing case 5 between the battery case 4 and the sealing case 5 formed in the above, and the opening end side of the side peripheral surface of the battery case 4 is closed by crimping. The electrode group 1a having a wound structure is accommodated in the battery and has a coin-shaped appearance.

As shown in FIG. 2 as a plan view of the electrode plate group 1a disposed inside the sealing case 5, the electrode plate group 1a is designed so that no useless space is formed in the circular space formed by the sealing case 5. It is formed in a space-efficient planar shape. Therefore, a battery with high volumetric efficiency and a large battery capacity per volume of the battery in combination with the wound structure can be configured. This electrode plate group 1a winds a positive electrode plate 7 shown in FIG. 3 (a) and a negative electrode plate 8 shown in FIG. 3 (b) via a separator 9 shown in FIG. 3 (c). Formed by

The positive electrode plate 7 is, as shown in FIG.
A positive electrode current collector formed of aluminum foil is formed in a band shape by a positive electrode plate material coated with a positive electrode material on both sides, and the positive electrode current collector is extended from one end of the positive electrode current collector from a position biased to one side in the width direction. The positive electrode lead 15 is formed. Further, as shown in FIG. 3 (b), the negative electrode plate 8 is formed in a strip shape by a negative electrode plate material in which a negative electrode material is applied to both surfaces of a negative electrode current collector formed of copper foil, and one end thereof is formed. A negative electrode lead 16 is formed by extending a negative electrode current collector from a position deviated in a direction opposite to the position where the positive electrode lead 15 is formed. The separator 9 is formed by forming a microporous polyethylene film in a tape shape, and is formed in a tape shape having a width larger than the width of the positive electrode plate 7 and the negative electrode plate 8.

As shown in FIG. 4, the positive electrode plate 7 and the negative electrode plate 8 have a separator 9 interposed therebetween, and are flatly wound so as to have a rectangular planar shape as shown in FIG. 17 is formed. Next, as shown in FIGS. 5A and 5B, the corners of the rectangle are cut. When the corners are cut by a heat cutter as shown in FIG. 5 (a), the separator 9 is melted on the cut surface, the separators 9 of each layer are welded, and the wound state is integrated without fixing with an adhesive tape. Can be fixed. Further, as shown in FIG. 5 (b), the corners can be die-cut into a circular arc under the spray of liquid nitrogen, and are punched out by cutting at a low temperature without causing an interlayer short circuit, and the cut surface is heat-cured. When the conductive resin is applied and cured, it can be fixed in a wound state.
As shown in FIG. 6, the electrode plate group 1 b whose corners are cut into an arc can further improve the space efficiency when housed in the sealing case 5.

The electrode groups 1a, 1b formed as described above
FIG. 2 shows that the positive electrode lead 15 and the negative electrode lead 16 extend from positions deviated from the center line in directions opposite to each other.
As shown in FIG. 6 and at different positions on the electrode groups 1a and 1b, as shown in FIG.
When the electrode group 1a is accommodated between the
The difference in the thickness distribution of 1b is suppressed, and a state is obtained in which there is no large difference in the tightening rates of the electrode groups 1a and 1b between the battery case 4 and the sealing case 5.

As shown in FIGS. 2 and 6, the sealing case 5
The electrode groups 1a and 1b, in which the negative electrode lead 16 is disposed downward, have a distal end portion of the negative electrode lead 16 peeped from between the inner wall of the sealing case 5 and the side surfaces of the electrode groups 1a and 1b. The negative electrode lead 16 is resistance-welded to the sealing case 5 by applying a welding electrode thereto. As shown in FIG. 8, the tip of the positive electrode lead 15 is ultrasonically welded to the inner surface of the battery case 4 placed side by side with the sealing case 5. Positive electrode lead 1
Since No. 5 is made of aluminum foil as described above, resistance welding is difficult, and ultrasonic welding is a suitable welding means.

The positive electrode lead 15 pulled out from the electrode groups 1a and 1b is connected to the battery case 4 and the negative electrode lead 16
Is connected to the sealing case 5 by welding, it is possible to take out a current having a small internal resistance, and it is possible to configure a coin-type battery having a high load current characteristic by the winding structure with higher performance.

After the positive electrode lead 15 and the negative electrode lead 16 have been welded, a gasket 6 is attached to the peripheral surface of the sealing case 5, and the battery case 4 is covered on the sealing case 5.
As shown in FIG. 1, the electrode groups 1 a and 1 b having a wound structure are housed in a state where the space between the battery case 4 and the sealing case 5 is sealed by crimping processing to bend the opening end side of the side peripheral surface inward. Completed coin-shaped battery.

In the configuration described above, the electrode groups 1a, 1b
Has a corner cut after winding, but as shown in FIG. 7, a plurality of laminated surfaces 17a to 17
e with a positive electrode plate 7a connected by connecting pieces 19a to 19d,
A negative electrode plate 8a formed by connecting a plurality of laminated surfaces 18a to 18e having arcs formed in the width direction with connecting pieces 20a to 20d is wound via a separator 9, and the laminated surfaces 17a to 17e and the laminated surfaces 18a to 18e are formed. The electrode group 1c may be configured to be laminated with the separator 9 interposed therebetween.

[0021]

As described above, according to the present invention, the positive electrode lead and the negative electrode lead overlap each other when a coin-type battery is formed by accommodating a wound electrode group in a shallow cylindrical case. Since it is not located at the position, the difference in the thickness distribution of the electrode group is suppressed. Therefore, when the electrode group having the wound structure is accommodated in the internal space formed by the battery case and the sealing case, there is no large difference in the stress rate applied to the electrode group, so that the positive electrode plate and the negative electrode plate Are obtained evenly. In this coin-type battery, the winding structure electrode group is housed in a circular housing space in a state of good volume efficiency, so that the discharge characteristics of the coin-type battery can be improved, and conventionally, only for devices with a small load current. The coin-shaped battery, which could not be applied, can be applied to a wider range, and can be used as a battery power source when a reduction in size, thickness, and weight is required, such as in portable devices. In addition, the positive electrode plate is welded to the battery case by the positive electrode lead, and the negative electrode plate is welded to the sealing case by the negative electrode lead, so that the current collecting property is stable, and the current collecting property is not impaired even when the internal pressure of the battery increases. A coin-shaped battery having a low internal resistance value can be provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a configuration of a coin-type battery according to an embodiment.

FIG. 2 is a plan view showing a state where an electrode group is arranged in a sealing case.

FIGS. 3A and 3B are development views showing the configuration of a positive electrode plate, FIG. 3B shows the configuration of a negative electrode plate, and FIG. 3C shows the configuration of a separator.

FIG. 4 is a perspective view showing an electrode plate group forming preparation.

FIGS. 5A and 5B are explanatory views showing cutting of a corner portion of a preparation for forming an electrode plate group using a hot cutter, and FIG. 5B showing die cutting at a low temperature.

FIG. 6 is a plan view showing a state where an electrode group is arranged in a sealing case.

FIG. 7 is a developed view showing a modified example of the positive electrode plate (a) and the negative electrode plate (b).

FIG. 8 is an explanatory view showing an example of a method for welding a positive electrode lead and a negative electrode lead.

FIG. 9 is a cross-sectional view showing a configuration of a conventional coin-type battery.

[Explanation of symbols]

 1a, 1b Electrode group 4 Battery case 5 Sealing case 6 Gasket 7, 7a Positive electrode plate 8, 8a Negative electrode plate 9 Separator 15 Positive electrode lead 16 Negative electrode lead

Claims (3)

[Claims] An electrode group in which a positive electrode plate and a negative electrode plate formed in a belt shape are flatly wound via a separator, a battery case and a sealing case formed in a circular half-shell body are mutually joined. A coin-shaped battery housed in an internal space in which openings are opposed to each other, wherein the electrode plate group has a positive electrode lead formed at a position deviated to one side in a width direction at one end side of a positive electrode plate. A negative electrode lead is formed at a position deviated in the width direction of one end of the negative electrode plate in a direction opposite to the extended position of the positive electrode lead, and the one end where the positive electrode lead and the negative electrode lead are formed is wound around the positive electrode. The plate and the negative electrode plate are wound with a winding width smaller than the diameter of the circular accommodating space of the internal space, and a positive electrode lead is provided on the battery case in a space vacated on both sides in the winding direction of the electrode group. The negative electrode lead is welded to the sealing case Coin-shaped battery, wherein the door. 2. The electrode plate group is formed by winding a positive electrode plate, a negative electrode plate, and a separator having a fixed width into a rectangular planar shape having a long side in a width direction, and then cutting the rectangular corners by a straight line or an arc. The coin-shaped battery according to claim 1, wherein the battery is formed. 3. An electrode plate group, wherein a positive electrode plate and a negative electrode plate are formed in a band shape in which circular or polygonal laminated surfaces are connected by connecting pieces having a predetermined width, and a laminated surface of the positive electrode plate and a negative electrode plate are formed. 2. The coin-shaped battery according to claim 1, wherein the coin-shaped battery is folded flat by a connecting piece so as to be laminated with a laminated surface via a separator.