JP2606057B2 - Flat battery - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flat battery in which the injected electrolyte can be sealed without overflowing during battery assembly and the radial expansion of the positive electrode mixture can be suppressed. It is about.

[0002]

2. Description of the Related Art In general, a flat battery has a structure in which a positive electrode mixture, a separator, and a negative electrode active material are disposed in a laminated state between a positive electrode can and a negative electrode terminal, and are sealed by an annular gasket. To assemble this type of battery, an annular gasket is fitted to the periphery of the negative electrode terminal to which the negative electrode active material is crimped, a separator is placed on the negative electrode active material, and a primary injection of an electrolytic solution is performed. A pellet-shaped positive electrode mixture is placed on the separator, a secondary injection of an electrolytic solution is performed, and then the positive electrode can is covered. The peripheral edge of the positive electrode can is crimped and sealed while applying a constant pressure from above and below the battery.

As the positive electrode mixture, a positive electrode mixture having a ring in which a positive electrode ring is fitted to the bottom of the positive electrode mixture is also used.

[0004]

In the flat battery described above, the upper surface of the annular gasket fitted to the peripheral portion of the negative electrode terminal and the upper surface of the positive electrode mixture are substantially at the same level. When the solution is advanced, the injected electrolyte easily overflows, sometimes causing an insufficient amount of the electrolyte. Performing the injection while paying attention to the state of absorption into the positive electrode mixture so as not to overflow the electrolyte took time and labor and was inefficient.

Therefore, usually, a space is formed between the annular gasket and the positive electrode mixture to form a stock yard for securing the electrolyte. However, this type has caused a cause of variation in battery performance due to radial expansion of the positive electrode mixture caused by discharge. On the other hand, since the positive electrode mixture with a ring suppresses radial expansion of the positive electrode mixture by the positive electrode ring, there is an advantage that the battery performance is stabilized with a small amount of electrolyte solution,
The use of the positive electrode ring has the disadvantage of increasing the cost, and the positive electrode ring covers the surface of the positive electrode mixture, resulting in a low absorption rate of the electrolytic solution.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to improve the annular gasket structure so that the same function can be achieved even if the positive electrode ring is abolished. It is an object of the present invention to provide a flat battery that does not overflow even if it hasten.

[0007]

SUMMARY OF THE INVENTION The present invention relates to a flat battery in which a positive electrode mixture, a separator, and a negative electrode active material are disposed in a laminated state between a positive electrode can and a negative electrode terminal and sealed by an annular gasket. The cross-sectional shape of the annular gasket has a U-shape in which an outer cylindrical portion and an inner cylindrical portion are integrated at a connecting portion, and a plurality of reinforcing rib plates are formed on an inner surface side of the inner cylindrical portion, and the plurality of reinforcing ribs are formed. The peripheral portion of the negative electrode terminal can be sandwiched between the rib plate and the outer cylindrical portion, and a space formed between the negative electrode terminal and the annular gasket inner cylindrical portion is used as a space for holding the injected electrolyte. The radial expansion of the positive electrode mixture is suppressed by the inner cylindrical portion of the annular gasket.

The annular gasket may be provided with an air vent hole communicating with the space for holding the injected electrolyte, or the outer surface of the annular gasket may be crushed by a pressing force at the time of sealing between the annular gasket and the positive electrode can. A gap forming means for forming a gap may be provided. Further, a plurality of cutout grooves communicating with the space for holding the injected electrolyte may be formed in the inner cylinder portion of the annular gasket.

[0009]

[Operation] A small amount of space is inserted between the reinforcing rib plate of the annular gasket and the outer cylinder at the peripheral edge of the negative electrode terminal and fastened, and the mounting position of the annular gasket is raised as high as possible to increase the inner volume. In addition, by using the space formed between the negative electrode terminal and the cylindrical portion of the annular gasket for holding the injected electrolyte, even if a large amount of electrolyte is injected from the positive electrode mixture at one time, it overflows. Lose it. Radial expansion of the positive electrode mixture during discharge can be prevented by the inner cylinder portion of the annular gasket reinforced by the reinforcing rib plate. Therefore, the conventional positive electrode ring becomes useless, and the omission of the positive electrode ring eliminates the possibility of covering the surface of the positive electrode mixture, so that the absorption time of the electrolyte injected into the positive electrode mixture can be reduced.

When an air vent hole communicating with the space for holding the injected electrolyte is provided, the injected electrolyte can easily flow into the space, and the volume of the space can be reduced by pressing the positive electrode can at the time of sealing. And the internal pressure is not increased, so that the liquid electrolyte is not discharged together with the exhaust.

The gap forming means provided on the outer peripheral surface of the annular gasket forms an air discharge passage connecting the inside and the outside of the battery between the positive electrode can and the positive electrode can at the initial stage of the sealing, and discharges the injected electrolyte accompanying the exhaust. However, since the pressure at the time of sealing causes the air discharge path to collapse and disappear, the sealing of the battery is not hindered.

If a plurality of notches are formed in the inner cylinder portion of the annular gasket, even if the separator is press-fitted at the tip of the inner cylinder portion of the annular gasket, the notch grooves are formed with respect to the space for holding the injected electrolyte. Since there is no problem because it serves both as a flow passage and an air vent, the work of fastening the annular gasket to the peripheral edge of the negative electrode terminal is facilitated. It also has a buffering effect on the outer periphery control of the positive electrode mixture due to the small diameter of the inner cylinder when the negative electrode terminal is completely fitted.

[0013]

FIG. 1 shows an embodiment of a flat battery according to the present invention, in which a positive electrode mixture 1, a separator 2 and a negative electrode active material 3 are disposed in a laminated state between a positive electrode can 4 and a negative electrode terminal 5, and There is no difference from the related art in that the gasket 6 seals the gasket. The difference is that the cross-sectional shape of the annular gasket 6 has a U-shape in which the outer tube portion 7 and the inner tube portion 8 are integrated by a connecting portion 9 as shown in FIGS. Is that a plurality of reinforcing rib plates 10 are provided on the inner wall surface. The distance L between the reinforcing rib plate 10 and the outer cylindrical portion 7 is smaller than the peripheral edge thickness of the negative electrode terminal 5.

In order to assemble a flat battery using the above annular gasket 6, as shown in FIG. 4, the distance between the annular gasket 6 and the periphery of the negative electrode terminal 5 on which the separator 2 is mounted on the negative electrode active material 3 is shown. By slightly fitting the L portion, the mounting position of the annular gasket 6 is increased so that the inner volume on the separator 2 is as large as possible. At this time, the tip portion of the inner cylinder portion 8 of the annular gasket 6 and the upper surface of the separator 2 are separated from each other at a certain interval without being in close contact with each other, so that the inside of the annular gasket 6 and the inner cylinder portion 8 The annular space 14 formed between the negative electrode terminal 5 and the peripheral portion can be communicated. Therefore, after the primary injection of the electrolytic solution (70 mg in the case of CR2032), as shown in FIG.
When the positive electrode mixture 1 is placed on the separator 2 and a second injection (150 mg in the case of CR2032) is performed from above the positive electrode mixture 1, the upper surface of the positive electrode mixture 1 is annular, as is apparent from FIG. Since the gap 14 is lower than the upper surface of the gasket 6 and functions as a stock yard for holding the electrolyte, it does not overflow even if the secondary injection is performed at once. After the secondary injection, the positive electrode can 4 is covered from above the annular gasket 6 as shown by a two-dot chain line, and then the positive electrode can 4 is pressed slowly as shown in FIG.
Finally, the outer periphery of the positive electrode can 4 is curled and sealed to obtain a flat battery of FIG. In this flat battery, when the positive electrode mixture 1 tries to expand in the radial direction due to discharge, the inner cylindrical portion 8 of the annular gasket 6 reinforced by the plurality of reinforcing rib plates 10.
Will prevent this.

In the illustrated example, an air vent hole 12 for bleeding air from a space 14 which is a space for holding the electrolytic solution is formed in the connecting portion 9 of the annular gasket 6. Further, on the outer peripheral surface of the annular gasket 6, air vents such as angular projections 13a or small projections 13b formed by leaving a part of the radius formed at the corner of the outer cylindrical portion 7 connected to the connecting portion 9 without removing it are taken. The gap forming means 13 is formed. At the beginning of the sealing, a gap is formed between the positive electrode can 4 and the annular gasket 6 between the positive electrode can 4 and the annular gasket 6 by the gap forming means 13. . Further, a plurality of cutout grooves 11 are formed in the inner cylindrical portion 8 of the annular gasket 6 so as to perform both functions as a flow path and a vent for the electrolyte holding space.

Taking the dimensions of each part described above as an example of a CR2032 battery in which the diameter of the positive electrode mixture 1 is 15.8 mm, the outer diameter of the annular gasket 6 is 19.6 mm and the inner diameter is 1 mm.
The outer rib 7 has a thickness of about 0.4 mm, the inner cylinder 8 has a thickness of about 0.13 mm, and the reinforcing rib plate 10 has a height of about 0.2 mm.
5 mm, width of about 0.65 mm, notch groove 11 is about 0.2 mm in width, about 1 mm in depth, through hole 12 is about 0.6 mm in diameter, small projection 13
b has a height of about 0.05 mm.

FIG. 7 shows a 2.7 KΩ continuous discharge performance test (2
0 ° C). From the figure, it can be seen that the present invention product 1 and the present invention product 2 are different types of the conventional product 1, the conventional product 2, the conventional product 3
It can be seen that the discharge performance is superior to any of the above.

[0018]

As described above, according to the present invention, it is possible to increase the position of the annular gasket to be fixed to the peripheral edge of the negative electrode terminal when assembling the battery, thereby increasing the internal volume.
In addition, since the space formed between the annular gasket and the negative electrode terminal can be used for securing the injected electrolyte, even if the injection of the electrolyte is accelerated, the overflow of the injected electrolyte from the annular gasket is ensured. Can be prevented. Since the inner cylindrical portion of the annular gasket reinforced by the reinforcing rib plate suppresses radial expansion of the positive electrode mixture, the conventional positive electrode ring can be omitted, and the number of parts can be reduced. Further, with the omission of the positive electrode ring, there is no longer anything covering the positive electrode mixture, so that the electrolyte solution absorption time can be shortened.

When an air vent hole is formed in the annular gasket to connect the space for holding the injected electrolyte and the outside, not only the flow of the injected electrolyte into the space is facilitated, but also the opening of the positive electrode can during sealing. When the pressure is reduced to reduce the volume of the space, exhaust is performed so as not to increase the internal pressure, and the exhausted electrolyte is not discharged together with the exhaust.

By providing a gap forming means on the outer peripheral surface of the annular gasket between the positive electrode can and the positive electrode can to form a gap which can be crushed by the pressurizing force at the time of sealing, the discharge of the electrolyte accompanying the air exhaust at the time of the sealing is performed. The prevention is made easier and more reliable, and the battery sealing function is not hindered.

When a plurality of cutout grooves are formed in the inner cylinder portion of the annular gasket, the notch is formed even when the end portion of the inner cylinder portion of the annular gasket is pressed against the separator when the annular gasket is fixed to the peripheral portion of the negative electrode terminal. Since the groove serves as a flow passage for the space for holding the injected electrolyte and for bleeding air, it is not necessary to pay attention so that the distal end portion of the inner cylindrical portion of the annular gasket does not press against the separator, thereby facilitating the operation.

[Brief description of the drawings]

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

2 is a sectional view taken along line AOB of the plan view of the annular gasket used in FIG. 1 and shown in FIG. 3;

FIG. 3 is a plan view of the annular gasket shown in FIG. 2;

FIG. 4 is a cross-sectional view showing a state at the time of primary injection when the flat battery of FIG. 1 is obtained.

FIG. 5 is a cross-sectional view showing a state during secondary injection.

FIG. 6 is a cross-sectional view showing a state after secondary injection.

FIG. 7 is a diagram showing a discharge performance test result.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Positive electrode mixture 2 Separator 3 Negative electrode active material 4 Positive electrode can 5 Negative terminal 6 Ring gasket 7 Outer cylinder part 8 Inner cylinder part 9 Connecting part 10 Reinforcement rib plate 11 Notch groove 12 Air vent hole 13 Gap formation means 14 Void

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-60-20459 (JP, A) JP-A-57-177853 (JP, A) Fully open 1986-167365 (JP, U) 70362 (JP, U)

Claims (4)

(57) [Claims] 1. In a flat battery in which a positive electrode mixture, a separator, and a negative electrode active material are disposed in a stacked state between a positive electrode can and a negative electrode terminal and sealed by an annular gasket, the cross-sectional shape of the annular gasket is outside. The tubular portion and the inner tubular portion form a U-shape integrated at the connecting portion, and a plurality of reinforcing rib plates are formed on the inner surface side of the inner tubular portion, and the plurality of reinforcing rib plates and the outer tubular portion are formed. Between the negative electrode terminal and the annular gasket inner cylinder portion as the space for holding the injected electrolyte, and the annular gasket inner cylinder portion. A flat battery wherein a radial expansion of the positive electrode mixture is suppressed. 2. The flat battery according to claim 1, wherein the annular gasket is provided with an air vent hole communicating the space for holding the injected electrolyte and the outside. 3. The flat gasket according to claim 1, wherein a gap forming means for forming a gap which can be crushed by a pressing force at the time of sealing is provided between the outer surface of the annular gasket and the positive electrode can. battery. 4. The flat battery according to claim 1, wherein a plurality of cutout grooves are formed in the inner cylindrical portion of the annular gasket to communicate the injected electrolyte holding space with the outside.