JP2000048776A - Cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate the substitution of air contained in the vicinity of an outer peripheral part of electrode plates with an electrolyte in a solution pouring process of a cell, and to suppress the increase of an internal resistance attributable to the deviation in quantity of the electrolyte by uniformly impregnating the electrolyte in the electrode plates. SOLUTION: In a cell in which electrode plates where a positive electrode plate, a negative electrode plate, and a separator interposed therebetween are spirally wound are stored in a bottomed cylindrical cell case 9, at least two rows of recesses 10 adjacent to an inner surface of the cell case 9 are formed in the height direction. The clearance between the adjacent recesses 10 is preferably changed from 0.5 mm to 5 mm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery in which a spirally wound electrode group is housed in a battery case, and more particularly to a battery having a groove on its inner surface to improve the permeability of an electrolyte into the electrode group. The present invention relates to a battery using a battery case designed for the above.

[0002]

2. Description of the Related Art A typical example of a battery provided with a group of electrode plates in which a positive electrode plate, a negative electrode plate, and a separator are spirally wound in a battery case is a lithium battery. The battery case used for this type of battery uses a steel plate that is nickel-plated on iron in terms of corrosion resistance to the electrolyte used, and mechanical properties against external stress and internal stress on the battery. By processing, it is molded into a bottomed cylindrical shape.

[0003] The discharge capacity, which is one of the important characteristics of a battery, is affected by the amounts of active materials of a positive electrode and a negative electrode housed in a battery case. The external dimensions of the battery case are standardized, and efforts have been made to reduce the thickness of the battery case and to study active materials in order to increase the discharge capacity within this range.

A battery of this type is completed through a process of inserting an electrode plate and then injecting an electrolytic solution into a case. The pouring step includes a step of depressurizing the inside of the battery case in which the electrode plate group is present using a vacuum pump, and a step of injecting an electrolytic solution into the battery case. By repeating the cycle several times, the air remaining around the electrode group is replaced by the electrolyte,
Positive and negative electrode plates impregnate.

[0005]

In the battery having the above-described structure, it is preferable that the gap between the electrode group and the battery case be minimized in view of the discharge capacity. Therefore, the electrode group is wound so that the outer diameter of the electrode group is substantially equal to the inner diameter of the battery case, and the outermost peripheral surface of the electrode group is housed in close contact with the battery case. On the other hand, the core part, which becomes the core part when the electrode plate group is formed, has the core removed after the formation and remains as a columnar space.

[0006] In the liquid injection step, the gaps between the electrodes of the electrode group and between the battery cases and the air existing in the space are replaced with an electrolyte, and the electrolyte is impregnated into the electrodes. When the gap between the battery case and the electrode group is small, 1
The amount of electrolyte on the outer circumference of the electrode plate group replaced by one injection cycle is smaller than that on the center, and it takes a long time to inject the electrolyte required as a battery, There is a difference in the amount of electrolytic solution impregnation between the central portion and the outer peripheral portion of the electrode plate group. For this reason, an unimpregnated portion of the electrolytic solution is generated in the outer peripheral portion, and the internal resistance of the battery is significantly increased.

[0007] In order to suppress the increase in internal resistance due to the uneven electrolyte solution impregnation, it is necessary to reduce the outer diameter of the electrode group and to uniformly impregnate the electrolyte throughout the entire electrode group. is there. However, a decrease in the outer diameter of the electrode group leads to a decrease in the discharge capacity of the battery, which is not preferable.

The present invention solves the problem caused by the relationship between the electrode group and the battery case in the liquid injection step, and facilitates the replacement of air contained near the outer periphery of the electrode group with the electrolytic solution. By uniformly impregnating the electrode group with the electrolytic solution, an increase in internal resistance is suppressed.

[0009]

In order to achieve the above-mentioned object, a battery according to the present invention comprises a bottomed cylindrical battery case for accommodating a group of electrode plates in which a positive electrode plate, a negative electrode plate and a separator are spirally wound. Has at least two adjacent concave portions, and has a groove formed so that each concave portion is parallel to the height direction of the battery.

[0010] In the battery using the battery case having the above structure, the electrolyte injected from the opening of the battery case accommodating the electrode group is provided adjacently and parallel to the height direction of the battery. Among the plurality of recesses, the battery pack descends toward the bottom surface of the battery case along at least one of the recesses, and penetrates from the outer peripheral portion of the electrode plate group in contact with the battery case. at the same time,
Air remaining in the electrode plate group can be released above the battery case from another concave portion different from the concave portion in which the electrolytic solution has dropped,
The replacement of the air and the electrolyte at the outer peripheral portion of the electrode plate group is quickly performed.

As a prior art for providing a groove in a battery case, Japanese Patent Application Laid-Open No. Hei 3-254074 discloses a technique in which a protrusion, a groove or a recess is provided on the surface of a battery case. According to this configuration, the battery case and the electrode can be brought into close contact with each other without the liquid film of the electrolytic solution present in the gap between the electrode and the battery case, and the storage characteristics and cycle life characteristics of the battery are improved. . On the other hand, the battery of the present invention uses one of a plurality of concave portions provided adjacently in the height direction of the battery as a gutter into which the electrolyte flows, and uses the other to remove air remaining near the outer peripheral portion of the electrode plate group. It is an object of the present invention to quickly replace an electrolytic solution in an outer peripheral portion of an electrode plate group and suppress an increase in internal resistance due to generation of a portion not impregnated with an electrolytic solution by using the exhaust passage as an exhaust passage.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below, and will be understood.

According to the first aspect of the present invention, since a groove formed of two or more adjacent recesses is provided on the inner wall of the battery case, when an electrolyte is injected into the battery, the outer periphery of the electrode plate group is particularly improved. The replacement of the air contained in the vicinity of the part with the electrolyte can be facilitated, and the permeability of the electrolyte in the electrode plate group can be made uniform.
This can suppress an increase in the internal resistance of the battery due to insufficient penetration of the electrolyte. Further, the time required for impregnating the electrode group with the electrolytic solution is also reduced, so that the time in the liquid injection step can be reduced.

Further, the invention according to claim 2 defines an interval between adjacent concave portions in the groove portion, and the interval is preferably in a range of 0.5 mm to 5 mm. If the interval between the concave portions is 0.5 mm or less, it becomes difficult to form the concave portions on the inner surface of the battery case by pressing. further,
In the groove, the adjacent concave portions are arranged so as to be substantially connected to each other. In such a state, not only does the width of the portion where the thickness of the battery case is reduced substantially increase,
The mechanical strength in the groove of the battery case and in the vicinity thereof is lower than in other parts.

On the other hand, when the interval is 5 mm or more, when the electrolyte is injected into the battery, the electrolyte injected into the circular space in the center of the electrode group removes air remaining in the electrode group. It is pushed to the outer periphery of the plate group. This air tries to escape to the upper part through the concave part, and will prevent the flow of the electrolyte solution,
This impedes the impregnation of the electrolyte from the outer periphery of the electrode group.

[0016]

Next, a preferred embodiment of the present invention will be described with reference to the drawings.

(Embodiment 1) FIG. 1 shows a structure of a battery according to the present invention, FIG. 2A shows a perspective view of an opening of the battery case in Embodiment 1, and FIG. FIG. In this embodiment, a lithium primary battery using manganese dioxide as a positive electrode active material and lithium as a negative electrode active material will be described.

An electrode group including a positive electrode and a negative electrode active material includes a positive electrode 1 in which a mixture containing manganese dioxide as a positive electrode active material as a main component is filled into a positive electrode core material to form a band, and a band-shaped negative electrode made of lithium metal. 2 and a separator 3 between these positive and negative electrodes.
, And spirally wound them.

Battery case 9 accommodating the obtained electrode plate group
Shows the inner surface of the battery as viewed from the opening direction as shown in FIG.
°, that is, equally divided into six, a set of grooves each having two sets of recesses was provided, and a total of twelve recesses were provided on the inner wall of the battery case. The interval between adjacent recesses in each groove 10 was 2 mm.

The battery case 9 also serves as a negative electrode terminal, and the electrode plate group and the battery case 9 are joined via the negative electrode lead 5. On the upper part of the battery case 9, a sealing plate 8, which also functions as a positive electrode terminal and a sealing of the opening of the battery case, was attached. The group of electrode plates and the sealing plate 8 were joined via the positive electrode lead 4. In order to prevent the occurrence of a short circuit due to the contact between the electrode group and the battery case and the sealing plate, an upper insulating plate 6 and a lower insulating plate 7 was deployed. After arranging the electrode group inside the battery case 9 and connecting to the terminals, the electrolyte is injected. As the electrolyte, lithium trifluoromethanesulfonate was used as a solute, and a 1: 1 mixture of propylene carbonate and dimethoxyethane was used as a solvent. After injecting the electrolyte,
The sealing plate 8 is arranged in the opening of the battery case, and the battery case 9
Was bent toward the inside of the case and sealed with a sealing plate 8 to obtain a battery in Example 1.

(Embodiment 2) In Embodiment 2, the structure except for the battery case 9 is the same as that of Embodiment 1. As shown in FIG. 3, the battery case 9 divides the battery case into four at intervals of 90 ° when viewed from the opening, and sets one set of grooves formed of three concave portions, and arranges one set for each. A total of 12 streaks of recesses were made on the entire inner surface of the battery case 9. The distance between adjacent concave portions was 2 mm as in Example 1.

(Comparative Example) As a comparative example, the configuration except for the battery case 9 was the same as that of the first embodiment. In the battery case 9, the inner surface is divided into 12 equal parts, that is, 30 equal parts.
°, the concave portion was arranged in each, and a concave portion composed of 12 stripes was provided on the entire inner surface of the battery case.

Fifty batteries were prepared for each of Examples 1, 2 and Comparative Examples, and the internal resistance of the batteries was measured. Table 1 shows the average of the measured internal resistances and the standard deviation representing the variation of the measured values.

[0024]

[Table 1]

As is clear from Table 1, the internal resistances of the batteries in Examples 1 and 2 are lower than those in Comparative Examples. At the same time, the variation in internal resistance was reduced. This facilitates replacement of the electrode plate group, particularly the air contained in the vicinity of the outer periphery thereof, with the electrolytic solution by providing two or more adjacent recesses adjacent to each other on the inner wall of the battery case,
This is because the permeation of the electrolyte solution in the electrode group was made uniform, and the unimpregnated portion in the electrode group was reduced.

In this embodiment, at least two recesses adjacent to the inner surface of the battery case are formed in the height direction. However, as shown in FIG. Then, a plurality of through-holes may be provided on the peripheral surface of the battery case, and the air existing on the bottom surface of the battery case in which the power generation element is housed may be discharged.

[0027]

According to the present invention, in a battery in which a positive electrode plate, a negative electrode plate, and a separator interposed between both electrode plates are spirally wound and a group of electrode plates is housed in a bottomed cylindrical battery case, two or more adjacent recesses are formed. By providing a groove in the height direction of the battery case on the inner surface of the battery case, when the electrolyte is injected into the battery, replacement of air contained in the vicinity of the outer periphery of the electrode plate group with the electrolyte is facilitated. In addition, the degree of penetration in the electrode group can be made uniform. As a result, an increase in the internal resistance of the battery due to insufficient penetration of the electrolyte can be suppressed.

[Brief description of the drawings]

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

FIG. 2A is a perspective view of an opening of a battery case according to the first embodiment. FIG. 2B is a cross-sectional view taken along the line II ′.

FIG. 3 is a cross-sectional view of a battery case according to a second embodiment.

FIG. 4 is a perspective view of a battery case showing another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Positive electrode 2 Negative electrode 3 Separator 9 Battery case 10 Recess

Claims (2)

[Claims] 1. A battery in which a positive electrode plate, a negative electrode plate, and an electrode plate group formed by spirally winding a separator interposed between these electrode plates are housed in a bottomed cylindrical battery case, the battery case has an inner surface. A battery having at least two recesses adjacent to a groove formed in a height direction of the battery. 2. The distance between adjacent recesses is 0.5 mm to 5 mm.
The battery according to claim 1, wherein