JPH11307067A - Seal member for sealing electrolyte, and lithium ion secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a seal member for sealing electrolyte excellent in a sealing property and a lithium ion secondary battery using the same. SOLUTION: This seal member 2 for sealing electrolyte has a disk part 2a with a hole at its center and a cylinder part 2b having a center axis substantially normal to the flat surface of the disk part 2a and continuously connected with the outer circumference of the disk part 2a. A chamfer part 2e is provided at a corner where an outer surface 2c of the disk part 2a crosses an outer surface 2d of the cylinder part 2b. A ring-shaped projection part 2f having a center axis in common with the disk part 2a is provided on the outer surface 2c of the disk part 2a. A lithium ion secondary battery 1 is provided with a constriction part 4 near an opening part 3a of a battery container 3. The seal member 2 for sealing the electrolyte is put by pressure between an upper part 4a of the constriction part 4 and a folded part 4c of the battery container 3 with a cap 5 held inside thereof. As a result, an air gap part 4f is produced between the chamfer part 2e and an inner surface 4d of the battery container 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a sealing member for sealing an electrolyte and a lithium ion secondary battery. In detail, by providing a chamfer at the corner where the outer surface of the disk portion and the outer surface of the cylindrical portion intersect, a sealing member for sealing an electrolyte which has attempted to improve sealing performance and a lithium ion secondary battery using the same are provided. It is related.

[0002]

2. Description of the Related Art Conventionally, in a battery container of a lithium ion secondary battery, a sealing member for sealing an electrolyte made of an elastic material has been used as a sealing member for sealing an electrolyte.

Here, a conventional electrolyte sealing member and a lithium ion secondary battery using the same are shown in FIG.
This will be described with reference to FIG. 3A and 3B, the electrolytic solution sealing member 2 has a disk portion 2a as one of its components. A cylindrical portion 2b is formed integrally with the disk portion 2a above the disk portion 2a in the Y-axis direction. Another cylindrical portion is formed integrally with the disk portion 2a below the disk portion 2a in the Y-axis direction.

In the figure, a battery container 3 has a substantially cylindrical shape having a bottom (not shown) in the lower part in the Y-axis direction and an opening 3a in the upper part in the Y-axis direction. Container. Further, a constricted portion 4 is formed near the opening 3a of the battery container 3 and at a position slightly closer to the center of the battery container 3 from the end where the opening 3a exists.

In the constricted portion 4, there is an upper portion 4a on the upper side in the Y-axis direction in the drawing. A curved portion 4e is provided outside the upper portion 4a. A bent portion 4c is continuous above the curved portion 4e in the Y-axis direction in the drawing.

[0006] In order to seal the battery container 3 using the electrolyte sealing member 2 as described above, as shown in FIG.
First, while aligning the central axis of the electrolyte sealing seal member 2 with the central axis of the battery container 3,
It is inserted from the opening 3a of the battery container 3. Next, the disk-shaped cap 5 is put inside the cylindrical portion 2b of the electrolyte sealing member 2.

Next, as shown in FIG. 3C, the sealing member 2 for sealing the electrolytic solution is sandwiched between the upper portion 4a of the constricted portion 4 and the bent portion 4c of the battery container 3 by applying pressure through the cap 5. wear.

As a result, the gap between the inner surface of the upper portion 4a and the outer surface 2c of the electrolyte sealing member in contact with the upper portion 4a,
Between the lower surface and the inner surface of the disc portion 2a of the electrolyte sealing member 2 in contact with the upper surface of the cap 5 and the inner surface of the electrolyte sealing member in contact with the cap 5 And between the inner surface of the bent portion of the battery container 3 and the outer surface of the electrolyte sealing seal member in contact therewith,
It receives a compressive force and becomes a sealed state.

[0009]

However, in the above-described conventional sealing member for sealing an electrolytic solution and the lithium ion secondary battery using the same, the lower surface of the cap 5 and the inner surface of the sealing member for sealing an electrolytic solution are used. And a large pressure is not generated between the inner surface of the upper portion 4a of the constriction 4 of the battery container and the outer surface 2c of the electrolyte sealing seal member in contact therewith, and the sealing performance is reduced by that much. And the defect that the electrolyte leaked occurred.

In order to prevent these drawbacks, the upper part 4a on which the sealing member for sealing the electrolyte is placed is elongated,
For example, measures have been taken to minimize the occurrence of bending in e or to apply a large force between the bent portion 4c and the upper portion 4a. However, even if these countermeasures were taken, they were not enough to prevent the failure of electrolyte leakage.

The present invention has been made in view of such problems, and has as its object to provide a sealing member for sealing an electrolytic solution having excellent sealing performance, and a lithium ion secondary battery using the same.

[0012]

SUMMARY OF THE INVENTION A sealing member for sealing an electrolytic solution according to the present invention has a circular plate portion having a hole at the center and a central axis substantially perpendicular to the plane direction of the circular plate portion. In a sealing member for sealing an electrolytic solution having a cylindrical portion continuous to the outer periphery of a plate portion, a chamfered portion is provided at a corner where the outer surface of the disk portion and the outer surface of the cylindrical portion intersect.

Further, the lithium ion secondary battery of the present invention is provided with a constricted portion near the opening of the battery container, and a disc portion having a hole in the center, and a substantially perpendicular to the plane direction of the disc portion. The outer surface of the disc portion in the electrolyte sealing seal member having a central axis in the direction and having a cylindrical portion continuous with the outer periphery of the disc portion is in contact with the upper inner surface of the constricted portion, and the upper portion of the constricted portion and the battery container In a lithium ion secondary battery in which a sealing member for sealing an electrolyte is sandwiched by applying pressure via a cap between the bent portion of the lithium ion secondary battery and the outer surface of the circular plate portion and the outer surface of the cylindrical portion, a chamfered portion is formed. There is a gap between the chamfered portion and the inner surface of the battery container.

According to the electrolyte sealing member and the lithium ion secondary battery of the present invention, the lower surface of the cap is provided by providing a chamfer at the corner where the outer surface of the disk portion and the outer surface of the cylindrical portion intersect. A large compressive stress is generated between the inner surface of the electrolyte sealing member and the inner surface of the electrolyte sealing member, and between the inner surface of the upper portion of the battery container and the outer surface of the electrolyte sealing member in contact therewith.

[0015]

Embodiments of the present invention will be described below. First, an embodiment of the invention relating to a sealing member for sealing an electrolyte will be described with reference to FIGS. In FIG. 1, FIG. 1A schematically illustrates a sealing member for sealing an electrolyte solution according to an embodiment of the present invention and a lithium ion secondary battery using the same.
FIG. 1 schematically shows a cross-sectional shape of an electrolyte sealing member according to an embodiment of the present invention, and FIG. 1C is a battery container to which the electrolyte sealing member according to the embodiment of the present invention is applied. 5 schematically shows the relationship between the electrolyte solution sealing member and the battery container in FIG.

1A and 1B, the electrolyte sealing member 2 has a disk portion 2a as one of its components. This disk portion 2a has a hole at the center as shown in the figure. That is, the disk portion 2a is
And a circular hole sharing the center axis of the disk portion 2a in a direction perpendicular to the plane direction (Y-axis direction).

A cylindrical portion 2b is formed integrally with the disk portion 2a above the disk portion 2a in the Y-axis direction. The cylindrical portion 2b has its central axis substantially perpendicular to the plane direction of the disk portion 2a (Y-axis direction), and is continuous with the outer periphery of the disk portion 2a.

A cylindrical portion 2h is formed integrally with the disk portion 2a below the disk portion 2a in the Y-axis direction. The cylindrical portion 2h has its central axis in a direction substantially perpendicular to the plane direction of the disk portion 2a (Y-axis direction), and is continuous with the inner periphery of the disk portion 2a.

In the figure, a chamfered portion 2e is provided at a corner where the outer surface 2c of the disk portion 2a and the outer surface 2d of the cylindrical portion 2b intersect. That is, the outer surface 2c of the disk portion 2a forms a plane perpendicular to the Y-axis direction, and the outer surface 2d of the cylindrical portion 2b forms a cylindrical curved surface having the central axis of the cylindrical portion 2b as its central axis. I have. The outer surface 2c of the disk portion 2a and the cylindrical portion 2b
Intersects with the outer surface 2d to form a circular intersection line. This is due to the corner formed between the disk portion 2a and the cylindrical portion 2b, that is, the sealing member 2 for sealing the electrolyte.
Is a corner formed outside the place where the disk portion 2a and the cylindrical portion 2b are connected to each other when the plane is cut along a plane including the central axis.
This angle is substantially 90 degrees from the cross-sectional shape as described above. However, as shown in the figure, a chamfered portion 2e is provided at this corner. This chamfer 2
The shape of e is approximately 45 with respect to the Y axis in the cross-sectional shape.
A straight line having a degree angle was used.

Although the shape of the chamfered portion 2e is a straight line having an angle of approximately 45 degrees with respect to the Y axis in the cross-sectional shape as described above, the shape of the chamfered portion 2e is not limited to these shapes. For example, the angle of a straight line may be not only 45 degrees with respect to the Y axis but also an acute angle or an obtuse angle. Further, it may be formed in an arc shape having a gentle curvature. Further, when making the cross-sectional shape into a curve, it may be not only an arc shape but also another function curve such as an elliptical shape, or another curve that cannot be expressed as a function shape. Further, a combination of a straight line and these curves may be used. The size of the chamfered portion 2e to be chamfered will be described later in detail.

As shown in the figure, in the electrolytic solution sealing member according to the embodiment of the present invention, in addition to providing the above-described chamfered portion 2e, a convex portion 2f can be provided on the disk portion 2a. That is, on the outer surface 2c of the disk portion 2a of the electrolyte sealing member 2, a ring-shaped convex portion 2f sharing the central axis of the disk portion 2a is provided. As shown in FIGS. 1A and 1B, the convex portion 2f has a rectangular shape in a cross section taken along a plane including the center axis of the electrolyte sealing member 2, and is formed integrally with the disk portion 2a. It is.

As shown in FIG. 2, the thickness of the projection 2f, that is, the thickness in the Y-axis direction is given by
In this case, the thickness t is 1.5 times the thickness t of the disk portion 2a, that is, 1.5t. Further, in the width of the convex portion 2f, that is, in the sectional shape, X
The width in the axial direction was represented by w. Note that the thickness t1 of the projection 2f,
The size and range of the width w will be described later in detail.

As a material for the above-mentioned electrolyte-sealing seal member 2, an elastic resin such as polypropylene or Teflon can be used. However, the material of the electrolyte sealing member 2 is not limited to these resins, and other materials that are not eroded by the electrolyte and have elasticity can of course be used. It is.

Next, the above-mentioned electrolyte sealing member 2
An embodiment of the invention relating to a lithium-ion secondary battery using the battery will be described with reference to FIGS. 1 and 2. FIG. FIG. 1A schematically illustrates a positional relationship between a battery container of a lithium ion secondary battery using the above-described electrolyte sealing seal member and an electrolyte sealing seal member applied thereto.

In the drawing, the battery container 3 has a substantially cylindrical shape having a bottom (not shown) in the lower part in the Y-axis direction in the drawing and an opening 3a in the upper part in the Y-axis direction. Container. Further, a constricted portion 4 is formed near the opening 3a of the battery container 3 and at a position slightly closer to the center of the battery container 3 from the end where the opening 3a exists. The constricted portion 4 has a radius smaller than a radius from the central axis of the battery container 3 to the outer periphery of the battery container 3 as a radius of the bottom portion 4f,
A groove formed by combining a gentle curve and a straight line portion from the outside of the battery case 3 toward the center of the battery case 3 is formed.

In the constricted portion 4, there is an upper portion 4a above the bottom portion 4f in the Y-axis direction in the drawing. That is, the bottom 4f forms a gentle curve, but its extension is
It is continuous on a plane perpendicular to the Y-axis direction. The portion of the plane perpendicular to the Y axis is the upper portion 4a. When viewed from above in the Y-axis direction in the drawing, the upper portion 4a shares a central axis with the battery container 3 and has a disk shape having a hole at the center.

A curved portion 4e is provided outside the upper portion 4a. That is, the curved portion 4e is a portion continuous to the outer periphery of the upper portion 4a, and has a constant curvature in a cross section including a central axis of the battery container 3 and has a certain curvature toward the upper side in the Y-axis direction in the drawing. It is curved and continues to be curved until it is parallel to the Y axis. Since the curved portion 4e is curved as described above, the curved portion inner surface 4d, that is, the surface existing inside the curved portion 4e, has a shape having a constant radius of curvature R in its cross-sectional shape.

A bent portion 4c is continuous above the curved portion 4e in the Y-axis direction in the drawing. This bent part 4
As shown in FIG. 1A, c is a portion having a cylindrical shape that shares the central axis of the battery container 3 with the central axis.
The bent portion 4c is a portion that is mechanically bent when the battery container 3 is sealed, and the shape after bending will be described later in detail.

Next, the electrolyte sealing member 2 described above is used.
A method of sealing a battery container with a sealing member for sealing an electrolyte when the is applied to the battery container 3 of the lithium ion secondary battery 1, its effects, and a mechanism for generating the effects will be described.

In order to seal the battery container 3 using the above-described electrolyte sealing member 2, as shown in FIG.
First, the sealing member 2 for sealing the electrolyte is moved from the opening of the battery container 3 while the cylindrical portion 2h is directed downward in the Y-axis direction while the center axis of the sealing member 2 for sealing the electrolyte is aligned with the center axis of the battery container 3. insert. At this time, the cylindrical portion 2h of the electrolyte sealing member 2 is fitted to the bottom 4f of the constricted portion 4 of the battery container 3.
Get inside the inside of.

Next, contact between the upper inner surface 4b of the constricted portion 4 of the battery container 3 and the outer surface 2c or the convex portion 2f of the disk portion 2a of the sealing member 2 for sealing an electrolyte will be described. Here, the electrolyte sealing member 2 is chamfered 2e.
However, the description will be made separately into one having the convex portion 2f in the disk portion 2a and one having the chamfered portion 2e and having the convex portion 2f in the disk portion 2a.

First, there is a chamfered portion 2e, but the disk portion 2a
When the electrolyte sealing member 2 having no convex portion 2f is used, the outer surface 2c of the disc portion 2a in the electrolyte sealing member 2 comes into contact with the upper inner surface 4b of the constricted portion 4. . On the other hand, when the electrolyte sealing member 2 having the chamfered portion 2e and the projection 2f on the disk portion 2a is used, the ring-shaped projection 2f of the electrolyte sealing member 2 is It comes into contact with the upper inner surface 4b of the constricted portion 4 of the container 3.

Next, the disk-shaped cap 5 is put inside the cylindrical portion 2b of the electrolyte sealing member 2. At this time, the cap 5 comes into contact with the upper surface of the disk portion 2a of the electrolyte sealing member 2.

Next, as shown in FIG. 1C, between the upper part 4a of the constricted part 4 and the bent part 4c of the battery container 3, the sealing member 2 for sealing the electrolyte is sandwiched by applying pressure through the cap 5. wear. That is, the bent portion 4c of the battery container 3
Are bent inward toward the central axis of the battery container 3, and the machine is bent in a direction facing each other between a bent portion 4 c that is bent and substantially parallel to the X-axis direction and an upper portion 4 a of the constricted portion 4 of the battery container 3. The bending portion 4c is further deformed by applying a mechanical force, and then the mechanical force is released. At this time, since the bent portion 4c is plastically deformed, the bent portion 4c tries to maintain the shape after the plastic deformation even after releasing the mechanical force.

On the other hand, when the above-described mechanical force acts, the electrolyte sealing seal member 2 is compressed between the lower surface of the cap 5 and the upper portion 4a of the constricted portion 4, and at the same time, 5 receives a compressive force between the upper surface of 5 and bent portion 4c. Therefore, in the portion of the electrolyte sealing member 2 which has received the compressive force, a reaction force against the compressive force is generated in a direction opposite to the direction of the compressive force. However, as described above, the bent portion 4 of the battery container 3
Since c attempts to maintain the shape after the plastic deformation even after the mechanical force is released by the plastic deformation, the deformation due to the reaction force of the electrolyte sealing seal member 2 is hindered. However, since the bent portion 4c of the battery container 3 has elasticity even after being plastically deformed, the bent portion 4c is slightly elastically deformed by the reaction force of the electrolyte sealing seal member 2, and the bent portion 4c is slightly upward in the Y-axis direction. Deform to. However, since its elastic deformation is small,
The reaction force of the electrolyte sealing member 2 is not completely released. Therefore, the electrolyte sealing member 2
Receives a compressive force, and the electrolyte-sealing sealing member 2 generates a reaction force opposing it to balance.

As a result, the gap between the upper inner surface 4b of the constricted portion 4 and the outer surface 2c of the electrolyte sealing member in contact therewith (when the disk portion 2a has the convex portion 2f, the convex portion 2f is also included). Between the lower surface of the cap 5 and the inner surface of the disk portion 2a of the electrolyte sealing member 2 in contact therewith, the upper surface of the cap 5 and the electrolyte sealing member 2 in contact therewith.
, And between the inner surface of the bent portion of the battery container 3 and the outer surface of the electrolyte sealing member in contact therewith, are in a sealed state by receiving a compressive force.

As can be seen from the drawing, a gap 4f is formed between the chamfered portion 2e of the electrolyte sealing member 2 and the inner surface 4d of the curved portion of the battery container 3. As described above, by generating the gap 4f between the chamfered portion 2e and the curved portion inner surface 4d of the battery container 3, the upper inner surface 4b of the constricted portion 4 of the battery container 3 and the electrolyte sealing seal member in contact therewith. 2 and the outer surface 2c (when the disk portion 2a has the convex portion 2f, the convex portion 2f is also included) and the cap 5
The sealing performance between the lower surface and the inner surface of the disk portion 2a of the electrolytic solution sealing member 2 that is in contact with the lower surface is improved. That is, as compared with the conventional electrolyte sealing member having no chamfered portion, the sealing member 2 having the chamfered portion 2e has better sealing performance. .

FIG. 3B shows a conventional electrolyte sealing member.
As shown in the figure, a corner 2g is present in a cross section of a plane including the central axis. That is, the corner 2g has an angle of substantially 90 degrees in its cross-sectional shape. Also,
When the conventional electrolytic solution sealing member is installed in the battery container and the bent portion 4c of the battery container 3 is bent,
As shown in FIG. 3C, the corner 2 g of the electrolyte sealing member 2 hits the inner surface of the curved portion 4 e of the battery container 3. However, as can be seen from the figure, the cross-sectional shape of the corner 2g of the electrolyte sealing member 2 has an angle of 90 degrees, and the cross-sectional shape of the curved portion 4e of the battery container 3 has a constant radius of curvature R. Therefore, the cross-sectional shapes of the two do not match.

Therefore, as shown in FIG. 3C, when the bending portion 4c of the battery container 3 is bent and a mechanical force is applied, the corner 2g of the electrolyte sealing seal member 2 becomes the curved portion 4e of the battery container 3. Due to this, it is deformed along the shape of the curved portion 4e under a larger pressure. In this case, since the amount of deformation of the corner 2g is large, a large compressive stress is generated in the corner 2g. Also,
When the mechanical force described above is released, the bent portion 4c
Is plastically deformed, so it tries to maintain the shape after plastic deformation. In addition, a force due to elastic deformation acts on the electrolyte sealing member 2 against the repulsion force of the electrolyte sealing seal member. However, as described above, a compressive stress is generated in the vicinity of the curved portion 4e due to a large elastic deformation.
Since the elastic deformation force generated by the bent portion 4c opposes the compressive stress generated near the curved portion 4e, most of the force is deprived against the compressive stress near the curved portion 4e. Therefore, the force obtained by subtracting the deprived force comes into contact with the lower surface of the cap 5, the inner surface of the electrolyte sealing member, and the inner surface of the upper portion 4 a of the constricted portion 4 of the battery container 3. It is used for sealing between the outer surface 2c of the electrolyte sealing member 2a. As a result, the lower surface of the cap 5 and the inner surface of the electrolyte sealing member, the inner surface of the upper part 4a of the constriction 4 of the battery container, and the outer surface 2c of the electrolyte sealing member in contact therewith.
Since no large pressure is generated between the two, the sealing performance is reduced by that much.

On the other hand, the corners 2 of the electrolyte sealing member 2
g and the curved portion 4e of the battery case 3, a large compressive stress is generated, so it seems that the sealing performance is excellent. However, a region where such a large compressive stress is generated is
The compressive stress generated is limited to a narrow area such as the corner 2g of the electrolyte sealing member 2 and the curved portion 4e of the battery container 3, and the resultant vector is oblique to the plane direction of the disk 2a. , The component force of the vector in the Y-axis direction perpendicular to the plane direction of the disk portion 2a is smaller than the total force of the combined vector, and as a result, the sealing performance is poor. Become.

On the other hand, when the electrolyte sealing member 2 according to the present invention is used, as shown in FIG. 1C, by providing a chamfered portion 2e, a conventional electrolyte sealing seal member is provided. The phenomenon that a large compressive stress concentrates near the inner surface 4d of the curved portion of the battery case 3 does not occur. Therefore, the force generated by bending the bent portion 4c of the battery case 3 is all generated by the cap 5 and the upper part 4 of the battery case 3.
This is used for compressive stress accompanying the deformation of the electrolyte sealing member 2 sandwiched between a. As a result, between the lower surface of the cap 5 and the inner surface of the electrolyte sealing member 2 in contact therewith, and the upper inner surface 4b of the battery container 3 and the outer surface of the electrolyte sealing seal in contact therewith. 2
A large compressive stress is generated between c and c. This allows
Between the lower surface of the cap 5 and the inner surface of the electrolyte sealing member 2 in contact therewith, and between the upper inner surface 4b of the battery container 3 and the outer surface 2c of the electrolyte sealing member in contact therewith. The sealing performance between them is significantly improved.

Since such a gap 4f is formed by providing the chamfer 2e in the electrolyte sealing seal member 2, conversely, the size of the chamfer 2e is formed so that the gap 4f is formed. Need to decide.

Hereinafter, the size of the chamfer 2e will be specifically described. Here, first, the curved portion 4e formed on the constricted portion 4 of the battery container 3 will be described again. The curved portion 4e has an upper portion 4a of the constricted portion 4 parallel to the X-axis direction and a bent portion 4c before bending is parallel to the Y-axis in a cross section taken along a plane including the central axis of the battery container 3. Thus, the shape is such that these two straight lines are smoothly continued by a curve formed with a constant radius of curvature R. Therefore, there are two connection points that connect the inner surface of the upper inner surface 4b and the inner surface of the bent portion 4c before bending and the inner surface 4d of the curved portion. That is, one is from the straight portion of the upper inner surface 4b to the curved inner surface 4d.
The other is a connection point connected to a straight line on the inner surface of the bent portion 4c before bending from the curve of the inner surface 4d of the curved portion.

Here, the description will be made with reference to the electrolyte sealing member 2.
To the chamfer 2e. When the shape of the chamfered portion 2e is a straight line in its cross-sectional shape, the chamfered portion 2e is formed with respect to a straight line connecting the two points corresponding to the two connection points described above.
Must be closer to the center of the electrolyte sealing member 2. That is, when the straight line of the cross section of the chamfered portion 2e crosses the straight line connecting the two points or exists outside the straight line connecting the two points, two points of the electrolyte sealing member 2 The portion existing outside the connecting straight line is compressed from the inner surface 4d of the curved portion of the battery container 3, and the generation of the compressive force causes the bent portion 4
The force used for sealing the battery container among the forces between c and the upper portion 4a is reduced. As a result, there arises a problem that the sealing performance of the electrolyte sealing member deteriorates, which has been a problem in the past.

When the cross-sectional shape of the chamfered portion 2 e is an arc having a constant radius of curvature, the radius of curvature must be larger than the radius of curvature R of the inner surface 4 d of the curved portion of the battery container 3. In this case, the point where the circle of the chamfered portion 2e intersects with the straight line of the outer surface 2c of the disk portion 2e must be closer to the center of the battery container than one of the above-mentioned two points. The point of intersection of the circle of the chamfered portion 2e and the straight line of the outer surface 2d of the cylindrical portion 2b needs to be closer to the opening 3a of the battery container 3 than to the other of the above two points. By satisfying these conditions, a gap is formed between the chamfered portion 2e and the curved portion inner surface 4d, so that unnecessary compressive force is not generated.

The cross-sectional shape of the chamfered portion 2e can be freely selected, such as another curve or a combination of a curve and a straight line. The cross-sectional shape is obtained by bending the bent portion 4c of the battery container 3 to seal the electrolyte. Of course, any shape can be adopted as long as a gap 4f is formed between the chamfered portion 2e and the curved portion inner surface 4d of the battery container 3 when the sealing member 2 is compressed.

When the bent portion 4c of the battery case 3 is bent, as shown in FIG. 1C, the bent portion 4c
A curved portion having a constant radius of curvature is formed between the cylindrical portion parallel to the Y axis of the battery container 3 and the electrolyte sealing seal member 2 in contact with the curved portion. A gap can also be provided for the part. In order to generate this gap, the sealing member 2 for sealing the electrolyte is used.
It is also possible to provide a thin portion or a groove. The formation of this gap makes it possible to further ensure the sealing performance between the upper surface of the cap 5 and the bent portion 4c.

Next, the convex portion 2 is formed on the electrolyte sealing member 2.
The case where f is provided will be described. When the convex portion 2f is attached to the outer surface 2c of the disk portion 2a of the electrolytic solution sealing member 2, and the bent portion 4c of the battery container 3 is bent, as shown in FIG. Due to the compressive force generated between 4c and upper part 4a, first, convex part 2f receives a compressive force from upper inner surface 4b of battery container 3, and convex part 2f is compressed and deformed. A compressive stress is generated with this deformation. When the convex portion 2f deforms, the outer surface 2c of the disk portion 2a comes into contact with the upper inner surface 4b of the battery container 3 and receives a compressive force. As a result, the convex portion 2f in which a compressive stress has already been generated and the outer surface 2c of the disk portion 2a that comes into contact later receive the compressive force at the same time, and both are deformed by the same compression. This deformation stops at a position where the sum of the two compressive stresses and the compressive force acting between the bent portion 4c and the upper portion 4a are balanced. As described above, since a larger compressive stress is generated in the protruding portion 2f than in the disc portion 2a excluding the protruding portion 2f, between the surface of the protruding portion 2f and the upper inner surface 4b, and in the disc portion 2a. A large compressive stress is generated between the portion corresponding to the convex portion 2f of the upper surface of the drawing 2a in the Y-axis direction and the lower surface of the cap 5 in the Y-axis direction. . As a result, a portion corresponding to the convex portion 2f between the surface of the convex portion 2f and the upper inner surface 4b, and the upper surface of the disk portion 2a in the Y-axis direction in the drawing, and the Y-axis of the cap 5 The sealing performance between the lower surface in the direction is significantly improved.

Next, with reference to FIG.
Thickness t1 and width w will be described. Here, the convex portion 2f
Is defined as the thickness of the convex portion including the thickness t of the disk portion 2a, and the thickness t1 of the convex portion is defined as the thickness t of the disk portion 2a.
Express by how many times. Here, the thickness t of the projection 2f
For 1, the optimum range is 1.1 to 3 times the thickness t of the disk portion 2a. If the thickness t1 of the projection 2f is smaller than 1.1t, the effect of concentrating the compressive stress on the projection 2f is reduced, and if the thickness t1 is larger than 3t, the projection 2f is increased.
Becomes too high, so that not only compression in the Y-axis direction but compression in the Y-axis direction, but deformation in the X-axis direction, that is, a buckling phenomenon, occurs.
This is because the compression force acting during the period “a” cannot be effectively used as the compression force in the Y-axis direction of the projection 2f.

Next, the width w of the projection 2f will be described.
Here, the length of the portion of the upper inner surface 4b of the battery container 3 parallel to the X axis is defined as the width of the upper inner surface. That is, in a cross section including the central axis of the battery case 3, the straight portion of the upper inner surface 4b is connected to the curved portion inside the constricted portion 4 at a portion near the central axis. Further, in a portion away from the central axis, the upper inner surface 4b is connected to a curved portion of the curved portion inner surface 4d. The distance between such two connecting points on a straight line passing through the central axis of the battery container 3 is defined as the width of the upper inner surface.

Here, the width w of the projection is expressed as a percentage of the width of the upper inner surface. Here, the width w of the projection is optimally in the range of 30 to 70% of the width of the upper inner surface. If the width w of the convex portion is smaller than 30% of the width of the upper inner surface, the compressive stress increases but the width w of the compressive stress is large.
In addition, when the width w of the convex portion is larger than 70% of the width of the upper inner surface, the region where the compressive stress is high becomes too large and the effect of concentrating the compressive stress is reduced. Because.

Although the above-described electrolyte sealing member 2 is applied to a cylindrical battery container, the electrolyte sealing member 2 is not limited to this cylindrical battery container. However, for battery containers of other shapes such as a square shape, the sealing member Y for sealing the electrolyte can be used.
Of course, it can be applied by appropriately changing the shape in the direction perpendicular to the axis.

As described above, the sealing performance of the battery container is remarkably improved by the electrolyte sealing member according to the present invention or the lithium ion secondary battery using the same.
As a result, the following advantages also occur at the same time.

That is, the sealing performance is improved, the rate of occurrence of defects due to electrolyte leakage is reduced, and the yield is improved.
Further, the processing pressure for deforming the container at the time of sealing can be reduced, and the processing variation can be reduced. As a result, the occurrence rate of processing shape defects decreases. Even if the width of the upper inner surface of the battery container is reduced, sufficient sealing performance can be obtained. Further, sufficient sealing performance can be obtained even if the width of the upper inner surface of the battery container varies to some extent. Further, even if the flatness of the upper inner surface of the battery container varies to some extent, sufficient sealing performance can be obtained.

It should be noted that the present invention is not limited to the above-described embodiment, but can adopt various other configurations without departing from the gist of the present invention.

[0056]

The present invention has the following effects. By providing the chamfered portion at the corner where the outer surface of the disk portion and the outer surface of the cylindrical portion intersect, the sealing performance of the electrolyte sealing seal member is improved. Further, by providing a ring-shaped convex portion sharing the central axis of the disk portion with the central axis of the disk portion on the outer surface of the disk portion, the sealing performance of the electrolyte sealing seal member is further improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an embodiment of the invention relating to an electrolyte sealing member and a lithium ion secondary battery using the same.

FIG. 2 is a sectional view showing an embodiment of the invention relating to a sealing member for sealing an electrolyte.

FIG. 3 is a cross-sectional view showing a conventional electrolyte sealing member and a lithium ion secondary battery using the same.

[Explanation of symbols]

1 Lithium ion secondary battery, 2 Sealing member for sealing electrolyte, 2a Disc portion, 2b Cylindrical portion, 2c
Outer surface, 2d ‥‥ outer surface, 2e ‥‥ chamfered portion, 2f ‥‥ convex portion, 2g ‥‥ corner, 3 ‥‥ battery container, 3a ‥‥ opening,
4 ‥‥ constricted part, 4a ‥‥ upper part, 4b ‥‥ upper inner surface, 4
c bend, 4d bend, inner surface, 4e bend, 5 cap

Claims (4)

[Claims] 1. An electrolytic device comprising: a disk portion having a hole at the center; and a cylindrical portion having a center axis substantially perpendicular to a plane direction of the disk portion and continuous with an outer periphery of the disk portion. A liquid sealing member, wherein a chamfered portion is provided at a corner where an outer surface of the disk portion and an outer surface of the cylindrical portion intersect. 2. A sealing member for sealing an electrolytic solution according to claim 1, wherein a ring-shaped convex portion sharing the central axis of the disk portion with the central axis of the disk portion is provided on the outer surface of the disk portion. 3. A circular part having a constricted part near an opening part of a battery container, a disk part having a hole in the center, and a center axis substantially perpendicular to a plane direction of the disk part. The outer surface of the disk portion in the electrolyte sealing member having a cylindrical portion continuous with the outer periphery of the plate portion is in contact with the upper inner surface of the constricted portion, and between the upper portion of the constricted portion and the bent portion of the battery container. To
In a lithium ion secondary battery in which an electrolyte sealing member is sandwiched by applying pressure through a cap, a chamfered portion is provided at a corner where an outer surface of the disk portion and an outer surface of the cylindrical portion intersect, and the chamfered portion is provided. A void portion is provided between the battery and an inner surface of the battery container. 4. A ring-shaped convex portion which shares the central axis of the disk portion with the central axis of the disk portion and which is in contact with the upper inner surface of the constricted portion is provided on the outer surface of the disk portion. The lithium ion secondary battery according to claim 3.