JPH10284018A - Sealed battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a defective ratio caused by the insertion of a generator and improve storing efficiency of sheath-cans. SOLUTION: This battery has a generator 5 constituted by winding positive and negative electrodes in a laminated shape or a spiral shape by interposing a separator and a cylindrical sheath-can 1 having an opening storing the generator 5 as components. The can 1 is constituted of an expanded diameter part 20 in which an opening end is made one end, a tilted part 21 connecting to the expanded diameter part 20 and a main body part 22 connecting to the tilted part 21. The side of the opening end part always has a larger inner diameter than that of the main body part 22. A difference in level is not provided on an inner wall from the main body 22 to the opening end.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealed battery,
More specifically, the present invention relates to a structure of an outer can used for a sealed battery.

[0002]

2. Description of the Related Art A power generator such as a spiral electrode group in which positive and negative electrodes are spirally wound with a separator interposed therebetween, and a laminated electrode group in which a large number of positive and negative electrodes are stacked with a separator interposed therebetween, are used.
After being housed in a cylindrical outer can having an opening, in a sealed battery in which the opening is sealed, in order to prevent damage to the edge of the generator when inserting the generator into the outer can. The outer dimensions of the power generator should be 0.3 mm
Generally, it is reduced by about 0.5 mm.

[0003] However, when the outer size of the power generator is made smaller than the inner diameter of the outer can, workability at the time of insertion of the power generator is improved, and damage to the power generator can be prevented. Is generated. (1) The outer can plays a role of applying an appropriate pressing force (constituent pressure) to a power generator such as a stored spiral electrode group.
Therefore, when the clearance between the outer can and the power generator is increased, the component pressure becomes insufficient, for example, the distance between the positive electrode and the negative electrode is increased, and the battery performance is reduced. (2) Conventionally, the outer dimensions of the power generating body have been reduced to increase the clearance with the inner surface of the outer can.
Therefore, it is necessary to sacrifice the battery capacity to some extent in order to easily insert the power generator. (3) On the other hand, if the clearance is made small in order to avoid a decrease in the power generation capacity, as described above, the insertion workability deteriorates, and a problem occurs that the power generator is damaged at the time of insertion.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems in the production of sealed batteries,
An object of the present invention is to devise an outer can structure in which a power generator can be easily inserted, thereby reducing a failure rate due to the insertion of the power generator, improving storage efficiency of the outer can, and providing a higher capacity sealed battery. I do.

[0005]

Means for Solving the Problems To achieve the above object, the invention according to claim 1 provides a power generator in which positive and negative electrodes are laminated or spirally wound with a separator interposed therebetween.
A cylindrical outer can having an opening for accommodating the power generator, and a sealed battery having the constituent elements, a diameter-enlarging portion having an opening end as one end, an inclined portion following the diameter-enlarging portion, and an inclined portion. It consists of the following main body, and the outer end is always larger on the open end side than the main body, and the outer can that has no step on the inner surface from the main body to the open end is used And

According to a second aspect of the present invention, in the sealed battery according to the first aspect, the thickness of the enlarged diameter portion is constant, and the thickness of the enlarged diameter portion is smaller than the thickness of the main body portion. It is characterized by the following.

[0007] The invention described in claim 3 is claim 1 or 2.
In the sealed battery described in the above, the inclination of the inclined portion is a linear function, and the inclination angle with respect to the axial direction of the outer can is 5.
It is characterized by being set to 0 degrees or less.

According to a fourth aspect of the present invention, in the sealed battery according to the first to third aspects, the thickness of the opening end of the enlarged diameter portion is 0.15 mm or more, and the clearance defined by Formula 1 is provided. The relationship between the inner diameter of the opening end and the outer diameter of the power generator is regulated such that the rate is 4.5% or more and 14.8% or less.

[0009]

(Equation 1)

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The significance of the constitution of the present invention and the embodiments of the present invention will be described.

FIG. 1 is a schematic cross-sectional view of a sealed battery according to the present invention, and FIG. 2 is a perspective view illustrating the structure of an outer can. The outline of the battery of the present invention will be described with reference to these drawings. In FIG. 1, 1 is an outer can made of an aluminum alloy, and 2 is a sealing plate made of the same aluminum alloy as the outer can. Reference numeral 3 denotes an external terminal plate, and reference numeral 4 denotes a gasket that insulates the sealing plate 2 from the external terminal plate 3. Reference numeral 5 denotes a power generator composed of positive and negative electrodes and a separator. This power generator may be either a spiral electrode group spirally wound between a positive electrode and a negative electrode with a separator interposed therebetween, or a laminated electrode group formed by laminating a large number of opposing electrode bodies with a separator interposed therebetween. A positive current collecting tab 6 and a negative current collecting tab 7 are respectively attached to the positive and negative electrodes, which are constituent members of the power generator 5, and the current collecting tabs 6 and 7 are further provided with the external terminal plate 3 and the outer can 1, respectively.
Is electrically connected to

As is clear from FIGS. 1 and 2, the outer can 1
Is opened, and the power generator 5 is inserted into the outer can 1 through the opening as shown in FIG. The electrolyte is injected through the opening. After the power generator and the electrolytic solution are stored in the outer can body, the sealing plate 2 incorporating the external terminal plate 3 and the gasket 4 is fitted into the opening, and the fitting surface is welded by a laser beam. More sealed. In addition, as a sealing method, a crimp method can also be used.

Next, the structure of the outer can, which is a feature of the present invention, will be described in detail. The outer can 1 according to the present invention is formed such that the inner diameter (A2) near the opening end is wider than the inner diameter (A1) of the power generator outer can body 22. Hereinafter, this portion having an inner diameter larger than that of the main body 22 is referred to as an enlarged diameter portion 20. An inclined portion 21 is provided between the enlarged diameter portion 20 and the main body portion 22, and the inclined portion 21 is continuous with the enlarged diameter portion 20 and the main body portion 22 without generating a step.

Note that the outer can body portion refers to an outer can portion in which a power generating element such as a power generator or an electrolyte is housed. Usually, in the sealed battery, a space of 5 to 6 mm exists between the lower surface of the sealing plate and the upper end of the power generating element, but the inclined portion of the present invention is generally located in this space.

By the way, in the case of batteries of the same size, the smaller the thickness of the outer can, the larger the power generator can be accommodated, so that the battery capacity can be increased accordingly. However, if the thickness of the outer can body is excessively reduced, the battery shape cannot be sufficiently maintained due to insufficient strength, which is not preferable. For this reason, in the present invention, the thickness of the outer can main body portion is kept as it is, the thickness is increased by reducing the thickness near the opening end (the enlarged diameter portion 20), and the gap between the vicinity of the opening end and the main body is further increased. Adopts an outer can with a structure in which a slope is provided and no step is formed.

With the outer can having such a structure, since the power generator can be inserted smoothly, the workability in the battery assembling process is remarkably improved, and even if the outer can has the same outer diameter, the outer can becomes larger. A generator can be inserted. Furthermore, since the thickness of the opening end to be fitted with the sealing plate is thin,
To that extent, heat loss in laser welding is reduced. Therefore, the laser traveling speed can be increased, and good welding can be performed even when the laser output is reduced.

As described above, an object of the present invention is to improve the efficiency of storing a power generator by smoothly storing the power generator. Therefore, the enlarged diameter portion 20 and the inclined portion 21
It is sufficient if the inner diameter of the outer can is increased from the outer can main body 22 side toward the outer can end without generating a step. Specifically, the shape of the enlarged diameter portion 20 may be any of a parallel cylindrical shape, a tapered shape, an outer round shape, and an inner round shape as long as the inner diameter is larger than the inner diameter of the main body portion. In addition, the inclined portion 21 may be configured such that one end is continuous with the enlarged diameter portion 20 without generating a step, and the other end is continuous with the main body 22 without generating a step. May be linear or curved.

Further, in the outer can according to the present invention,
The boundary between the enlarged diameter portion 20, the inclined portion 21, and the main body portion 22 may not be clear. This is because, from the viewpoint of insertion of the power generator, smoother insertion is easier if the boundary is not clear. However, in the enlarged diameter portion 20 near the outer can end,
The sealing plate 2 is fitted. Therefore, from the aspect of easy fitting,
It is preferable that the side surface of the enlarged diameter portion 20 has no inclination.
It is preferable that the length in the depth direction of 0 is substantially the same as the thickness of the sealing plate 2.

On the other hand, as a preferable requirement for smoothly inserting the power generator, the inclination angle θ of the inclined portion 21 with respect to the axial direction of the outer can is preferably 50 degrees or less. If the inclination angle θ exceeds 50 degrees, smooth insertion of the power generator is hindered, and as a result, the power generator is damaged at the time of insertion. Furthermore, the thickness of the outer can body is usually 0.3
When the thickness of the outer can body is about 0.3 mm to 0.8 mm, the thickness of the enlarged diameter portion is preferably set to 0.15 mm or more, and the inner diameter of the enlarged diameter portion is set to 0.15 mm or more. And the outer diameter of the power generator are preferably set such that the clearance ratio defined by the following equation 1 is not less than 4.5% and not more than 14.8%. When the outer can and the power generator satisfy this condition, the power generator can be smoothly inserted into the outer can, and an appropriate component pressure can be applied to the side of the outer can against the stored power generator. That is, since sufficient and appropriate storage efficiency can be ensured, the battery performance can be improved at the same time as the yield in battery manufacturing can be improved.

[0020]

(Equation 1)

[0021]

EXAMPLES Hereinafter, the contents of the present invention will be described more specifically based on examples. (Embodiment 1) The sealed battery of Embodiment 1 is shown in FIGS.
It has the same structure as. The outer can used in Example 1 has the following shape. That is, the outer dimensions of the outer can are as follows: thickness (A3) 6 mm, width (B3) 34
mm, and the length (C) in the height direction is 65 mm. The inner dimensions of the outer can body are 4.5 mm in the thickness direction (A1), 32.5 mm in the width direction (B2), and 6 in the height direction (C).
4 mm, and the thickness (T1) of the outer can body is 0.75 m
m. On the other hand, the inner dimension of the opening end is the length in the thickness direction (A
2) is 5 mm, the width in the width direction (not shown) is 33 mm, and the thickness (T2) is 0.5 mm. The enlarged diameter portion 20 having a constant thickness starting from the opening end has a thickness (T2) of 0.5.
mm, the length in the depth direction is 0.7 mm, and the length in the depth direction of the inclined portion 21 subsequent thereto is 5.3 mm (the inclination angle is 2.7 degrees).

The shape and structure of the power generator 5 inserted into the outer can 1 are as follows. That is, the power generator 5 includes a positive electrode in which lithium cobalt oxide (LiCoO ₂ ) is held on both surfaces of a positive electrode current collector made of aluminum foil, and a negative electrode in which natural graphite is held on both surfaces of a negative electrode current collector made of copper foil. Are spirally wound through a separator made of a polyethylene microporous membrane. The dimensions of this spiral power generator are 4.4 mm in the thickness direction (a) and 3 mm in the width direction (b).
2.4 mm, height direction is 60 mm.

The battery assembly method is as follows.
Is inserted into the main body of the outer can 1, and then LiP
An electrolytic solution comprising a mixed solvent of ethylene carbonate and diethyl carbonate (volume ratio 1: 1) in which 1 mol of F ₆ is dissolved is injected. Thereafter, a sealing plate 2 and the like were arranged at the opening of the outer can 1, and laser welding was performed to obtain a sealed lithium ion secondary battery.

The enlarged diameter portion 20 and the inclined portion 21 of the outer can were formed by ironing.

Comparative Example 1 A sealed battery according to Comparative Example 1 was produced in the same manner as in Example 1 except that the inclination angle θ of the inclined portion was set to 80 degrees.

(Comparative Example 2) An outer can having no enlarged diameter portion and no inclined portion was used, and the length (a) in the thickness direction was 4.2 m.
m, a sealed battery according to Comparative Example 2 was produced in the same manner as in Example 1 except that a power generator having a length in the width direction (b) of 32 mm and a length in the height direction of 60 mm was used.

FIG. 4 shows a schematic sectional view of the battery of Comparative Example 2. 4, 101 is an outer can, 102 is a sealing plate, 10
3 is an external terminal plate, 104 is a gasket, 106 is a positive electrode current collecting tab, and 107 is a negative electrode current collecting tab. Also, 105
Is a spiral power generator. The power generator 105 has a thickness direction and a width direction smaller than those of the first embodiment by reducing the amount of the active material paste applied to the positive and negative current collectors. It is.

Comparative Example 3 A sealed battery according to Comparative Example 3 was produced in the same manner as in Example 1 except that an outer can having no enlarged diameter portion and no inclined portion was used. In Comparative Example 3, a power generator having the same size as that of Example 1 was used. Therefore, Comparative Example 3 differs from Comparative Example 2 only in the dimensions of the power generator.

Evaluation of each battery In the above-described various battery manufacturing processes, the insertion load required for housing the power generator in the outer can was measured. Then, the case where the insertion weight exceeded 4.2 kg was regarded as insertion failure, and the insertion failure rate was calculated. Table 1 shows the results. Table 1 shows the results when the number of measurements was 1,000.

For Example 1 and Comparative Example 2, 50 batteries were prepared, each battery was charged at 900 mA until the battery voltage reached 4.1 V, and the battery voltage was further reduced to 4.1 V. While maintaining the charge current value gradually 20m
The battery was charged in a manner to reduce the charge to A. Next, after a pause of 5 minutes, the discharge capacity of each battery was measured by a method of discharging at a current value of 900 mA until the battery voltage reached 2.75 V.
In addition, the power generator occupancy of these batteries (the ratio of the power generator volume to the outer can volume) was calculated. Table 2 shows these results.
Shown in Table 2 shows the results when the number of measurements was 50.

Further, 10 fully charged various batteries are
Each of the samples was stored for 20 days under the conditions of 70 ° C. and 90% relative humidity, and the presence or absence of electrolyte leakage was visually observed. Table 3 shows the results. Table 3 shows the results when the number of measurements was 100.

[0032]

[Table 1]

[0033]

[Table 2]

[0034]

[Table 3]

In Table 1, the failure rate when the power generator is inserted is
Example 1 <Comparative Example 1 ≦ Comparative Example 2 << Comparative Example 3.
As is apparent from the results in Table 1, the enlarged diameter portion and the inclined portion are provided, and the inclination angle θ of the inclined portion with respect to the depth direction is set to 2.
In Example 1 in which the angle was set to 7 degrees, the inclination angle θ was set to 80 degrees, and in other respects, Comparative Example 1 in the same manner as in Example 1 was used. The insertion of the power generator into the outer can was smoother than in Comparative Example 2 in which the size was reduced, and in Comparative Example 3 in which the power generator was the same as that of Example 1 without providing the enlarged diameter portion and the inclined portion.

Further, Example 1 in Tables 1, 2 and 3 was used.
In comparison with Comparative Example 2, by providing the enlarged diameter portion and the inclined portion, even if a power generator of a larger size is inserted into the outer can, the defective rate during insertion and the rate of occurrence of liquid leakage can be reduced, and the insertion rate It has been confirmed that the decrease in the amount leads to an improvement in the discharge capacity and an improvement in the storage test results.

Based on the above test results, the relationship between the clearance ratio and the defective insertion rate defined by the following equation (1) and the relationship between the inclination angle θ of the inclined portion and the defective insertion ratio were examined in detail.

[0038]

(Equation 1)

The reason why the clearance ratio is defined as Equation 1 is that the component pressure acting in the thickness direction of the power generator greatly affects the battery performance.

Here, the relationship between the inner diameter of the enlarged diameter portion, the clearance between the generator and the insertion failure rate was examined by the following method. First, the length in the depth direction of the enlarged diameter portion 20 is 0.7 mm,
The thickness T2 is 0.10 mm, 0.15 mm, respectively.
0.20mm, 0.25mm, 0.30mm, 0.40
mm, 0.50 mm, 0.60 mm, and 0.65 mm without inclination, the thickness T1 of the main body 22 is set to 0.75 mm (common), and the inclined portion 2 between the enlarged diameter portion 20 and the main body 22.
The inclination angle θ of ¹ was set to tan ^-1 [(T1-T2) /5.3], and nine types of rectangular outer cans having such an enlarged portion and an inclined portion were produced.

Nine types of sealed batteries were produced using this outer can in the same manner as in Example 1 except for the other conditions. Then, the moldability of the outer can and the quality of the laser welding were observed, and the rate of defective insertion of the power generator and the rate of occurrence of liquid leakage during the production were examined in the same manner as above. Table 4 shows the results.
Each of the outer cans has a common length of 6 mm from the outer can end to the main body. Therefore, as the thickness T2 of the enlarged diameter portion 20 is smaller, the inclination angle θ of the inclined portion 21 is larger.

The relationship between the inclination angle θ of the inclined portion and the defective insertion rate was examined by the following method. Set the thickness T1 of the main body to 0.
75 mm, the thickness T2 of the enlarged diameter portion is 0.5 mm, the length in the depth direction of the enlarged diameter portion is 0.7 mm, and the end of the enlarged diameter portion on the main body side (the position of 0.7 mm from the opening end to the main body side). ) From the main body side, the inclination angles θ are 2, 10, 20, 30 respectively.
Degrees, 40 degrees, 50 degrees, 60 degrees, 70 degrees, 75 degrees, 80
There were prepared 12 types of rectangular outer cans provided with inclined portions of 90 degrees, 85 degrees, and 90 degrees. Twelve types of sealed batteries were manufactured using this outer can in the same manner as in Example 1 except for the other conditions.
The power generator insertion failure rate was examined in the same manner as described above. Table 5 shows the results.

[0043]

[Table 4]

[0044]

[Table 5]

In Table 4, it can be seen that when the clearance rate defined by the equation 1 is 4.5% or more, the power generation unit insertion failure rate and the liquid leakage occurrence rate can be reduced to 0%. However, when the thickness of the opening end is less than 0.15 mm, the material strength is low, so that the yield at the time of molding the outer can has deteriorated. When the thickness of the opening end is less than 0.15 mm, workability in laser welding is deteriorated due to insufficient thickness, and
It was found that the welding strength was insufficient. For this reason, it is preferable that the thickness of the opening end (the enlarged diameter portion) be 0.15 mm or more, and the clearance ratio in relation to the length in the thickness direction of the power generator be 4.5% or more.

Further, from Table 5, it can be seen that when the rising angle θ of the inclined portion is 50 degrees or less, the power generator insertion failure does not occur. From this, the rising angle θ of the inclined portion
Is preferably 50 degrees or less. If the inclination angle exceeds 50 degrees, the inclination is so steep that the power generator cannot be inserted smoothly.

When the outer diameter of the outer can is kept constant, the outer diameter of the power generator is limited to the inner diameter of the outer can body in order to increase the storage efficiency of the outer can (volume occupied by the power generator). Here, the above conditions of the present invention are significant. That is, in order to make the outer diameter of the power generator close to the inner diameter of the outer can body as much as possible, and to smoothly insert the power generator, it is preferable to increase the inner diameter of the outer can end, as described above. Also in this case, it is not preferable that the thickness of the opening end is less than 0.15 mm.

On the other hand, even when the thickness is 0.15 mm or more,
This alone does not produce any special effects, but in the present invention, in addition to this requirement, the relationship between the inner diameter of the outer can end and the outer diameter of the power generator is adjusted so that the clearance ratio is 4.5% or more. Stipulated. When the two conditions of the clearance ratio of 4.5% or more and the thickness of the opening end portion of 0.15 mm or more are satisfied, the power generating body having a larger outer diameter (volume) can be used as long as the insertion failure rate does not occur. , So that an appropriate component pressure can be secured. Therefore, a sealed battery with high capacity and high reliability can be obtained. Further, in the present invention, since the thickness of the opening end is reduced, heat loss in laser welding is reduced. Therefore, the laser traveling speed can be increased or the laser output can be reduced, and the productivity is improved accordingly.

(Other Matters) The present invention can be applied to various sealed batteries such as sealed alkaline batteries and sealed lithium batteries, and the types of positive and negative active materials are not limited at all.

[0050]

As is clear from the above, according to the present invention, the workability of manufacturing a sealed battery is improved by simple means, and the yield in battery manufacturing is improved. Moreover, according to the present invention, the volume of the power generation main body housed in the outer can can be increased, so that the battery capacity can be improved.

[Brief description of the drawings]

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

FIG. 2 is a perspective view of a main part for describing the structure of an outer can according to the present invention.

FIG. 3 is an explanatory view showing that a power generator is inserted into an outer can according to the present invention.

FIG. 4 is a schematic sectional view showing a structure of a sealed battery according to Comparative Example 2.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Outer can 2 Sealing plate 3 External terminal board 4 Gasket 5 Power generator 6 Positive electrode current collecting tab 7 Negative electrode current collecting tab 20 Large diameter part 21 Inclined part 22 Body part

Claims (4)

[Claims] 1. A sealed battery comprising a power generator formed by laminating or spirally winding positive and negative electrodes with a separator interposed therebetween, and a cylindrical outer can having an opening for accommodating the power generator. The outer can is composed of an enlarged portion having an open end as one end, an inclined portion following the enlarged portion, and a main body portion following the inclined portion, and the opening end side is always closer to the main body portion. A sealed battery having a large inner diameter and no step formed on an inner surface from a main body to an open end. 2. The apparatus according to claim 1, wherein the thickness of the enlarged diameter portion is constant and smaller than the thickness of the main body.
The sealed battery as described. 3. The inclination of the inclined portion is a linear function,
3. The sealed battery according to claim 1, wherein the inclination angle of the outer can with respect to the axial direction is set to 50 degrees or less. 4. The thickness of the opening end of the enlarged diameter portion is 0.15.
mm or more, and the relationship between the inner diameter of the opening end and the outer diameter of the power generator is regulated so that the clearance rate defined by Equation 1 is 4.5% or more and 14.8% or less. The sealed battery according to any one of claims 1 to 3, wherein: (Equation 1)