JPH09306444A - Sealed battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate the fitting, and to improve the laser welding of an abutment part so as to improve the air-tightness by providing an inclined part at a part of an outer peripheral side surface of a sealing body, which abuts on an opening part of an upper part of a rectangular cylindrical can having a bottom. SOLUTION: A rectangular cylindrical can 1 having a bottom, which is made of stainless steel or the like, houses a power generating element, which is formed of a positive electrode, a negative electrode and the electrolyte, and works as a negative electrode terminal. A sealing body 4 made of stainless steel and having a peripheral edge 3 and an inclined part 2 can be easily made to abut for fitting by placing the inclined part 2 on a top surface of the upper opening part of the can 1, and lightly pressurizing it. Laser welding is performed to the abutment part so as to securely bond the sealing body 14 and the can 4 so as to secure the sufficient air-tightness. A positive electrode terminal 9 made of stainless steel, which is projected from an upper and a lower surfaces of the sealing body 4, is air-tightly fitted to the sealing body 4 through a safety valve mechanism 12 and an insulating material 8 made of glass.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealed battery having a bottomed rectangular tubular outer can.

[0002]

2. Description of the Related Art In recent years, notebook computers, portable devices, and the like are becoming smaller, lighter, and higher in performance, and secondary batteries used as power sources for these devices are becoming higher in capacity or higher in energy density. The demand is increasing. As the secondary battery,
Recently, a lithium ion secondary battery has been developed as a non-aqueous electrolyte secondary battery.

In addition, due to the trend toward smaller size, lighter weight and higher performance of equipment using the lithium ion secondary battery, not only is there a demand for higher capacity and higher energy density of the secondary battery, Various demands have come to be made on the shape. For example, a prismatic lithium-ion secondary battery having the shape of a bottomed rectangular cylinder has been increasingly demanded as a battery that can function in a limited space inside the device.

Further, a non-aqueous electrolyte secondary battery such as a prismatic lithium ion secondary battery having the shape of a rectangular cylinder with a bottom has a stable hermeticity for a long period from the viewpoint of its performance.
Since airtightness is particularly required, it is necessary to adopt a sealing method having extremely high airtightness. Therefore, for the prismatic lithium ion secondary battery, for example, the sealing method shown in FIGS. 4 and 5 has been proposed.

The bottomed rectangular tubular outer can 21 houses a power generating element including at least a positive electrode, a negative electrode, and an electrolyte, and also serves as either the positive electrode or the negative electrode. The sealing body 22 is fitted to the outer can 21 and is hermetically attached to the outer can 21 by laser welding the upper surface of the upper opening of the outer can 21 and the outer peripheral edge of the sealing body 22. There is. Further, the other-polarity pin terminal 26 is attached to the hole 27 of the sealing body 22 through the insulating material 25 by a hermetic seal so that both ends thereof project from the upper and lower surfaces of the sealing body 22. Although it is relatively easy to perform precision processing of the sealing body 22 by press molding, the outer can 2
In the case of manufacturing No. 1 by deep drawing, it was difficult to improve the accuracy of the inner diameter of the outer can 21 as the drawing depth of the outer can 21 increased.

As a result, since the inner diameter of the outer can 21 varies, when the sealing body 22 is fitted into the upper opening of the outer can 21, the inner surface of the upper opening of the outer can 21 and the sealing body. When fitting the outer peripheral edge of 22, there are those that can be fitted easily and those that cannot be fitted easily. In particular, with respect to those that are not easily fitted, there is a problem that the outer peripheral edge of the sealing body 22 cannot be fitted loosely to the upper surface of the upper opening of the outer can 21.

Therefore, the sealing body 22 is attached to the outer can 21.
, The upper portion of the sealing body 22 is externally pressed by a jig to make the upper surface of the upper opening of the outer can be rough and then laser-welded to seal the battery with good airtightness. A method was proposed to keep the total height of the.

However, these methods require not only complicated operations, but are also effective only in the case of an outer can having a small variation in inner diameter.

[0009]

Conventionally, since the upper surface of the upper opening of the outer can and the outer peripheral edge of the sealing body were not fitted to each other, the inner surface of the upper opening of the outer can and the sealing body of the outer can are not. When laser welding is applied to the outer peripheral edge, welding failure is likely to occur, resulting in poor battery airtightness.

For the same reason, there is a problem that the sealing body cannot be fitted in a fixed position of the outer can and the total height of the battery fluctuates.

[0011]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides an outer can, which is a rectangular cylinder with a bottom and which houses a power generating element including at least a positive electrode, a negative electrode and an electrolyte, and the outer can. Is provided with an outer peripheral edge that is fitted to the inner surface of the upper opening of the outer can contacting the inner surface of the upper opening of the outer can and a sealing body having an inclined portion. Further, it is preferable that the angle of the inclined portion provided on the sealing body is in the range of 1 ° to 45 ° because the effect of improving the airtightness of the battery and the assembling accuracy is great. The shape of the inclined portion provided on the sealing body is, for example, as shown in FIG.
(B), as shown in FIG. 3 (c), when linearly inclined from the upper surface to the lower surface (a), when there is a straight portion at the upper portion and an inclined portion below the straight portion, FIG. And a case where there is an inclined portion at the corner where the short surface and the long surface intersect, FIG.
Various shapes such as a curved shape such as an arc shape or the like can be used instead of the linear shape of the inclined portion.

For this reason, when the sealing body having the outer peripheral edge and the inclined portion of the side surface is fitted on the inner surface of the upper opening of the outer can having the bottomed rectangular tubular body, the inclined portion of the sealing body is utilized. As a result, the sealing body can be easily fitted.
When the outer can is manufactured by press-molding deep drawing, it is difficult to improve the accuracy of the inner diameter of the outer can as the drawing depth of the outer can becomes deep, and the inner diameter varies, but the sealing body By providing the inclined portion with a slightly larger outer diameter, it is possible to absorb variations in the inner diameter of the outer can during press molding. By providing an inclined portion on the sealing body, the outer peripheral edge of the sealing body can be easily fitted to the inner surface of the upper opening of the outer packaging can, and the upper end of the outer packaging can and the outer peripheral edge of the sealing body are randomly fitted. It is possible to keep the total height of the battery constant.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, when the outer peripheral edge of the sealing body is fitted to the inner surface of the upper opening of the outer can having a bottomed rectangular tubular body, the fitting is facilitated, and the upper opening of the outer can is formed. The outer peripheral edge and the side surface of the sealing body have inclined portions so that the upper surface of the sealing body and the outer peripheral edge of the sealing body can be satisfactorily laser-welded and the airtightness can be improved.

Further, since the outer peripheral edge of the sealing body is fitted to the inner surface of the upper opening of the outer can by utilizing the inclined portion of the sealing body, the upper portion of the sealing body is lightly applied from outside by a jig. By pressing, the upper surface of the upper opening of the outer can and the outer peripheral edge of the sealing body can be easily fitted to the upper surface of the upper opening of the outer can to keep the total height of the battery constant. it can.

[0015]

EXAMPLES Examples will be described with reference to the drawings.
1 and 2, a power generating element including at least a positive electrode, a negative electrode, and an electrolyte is housed in an outer case 1 having a bottomed rectangular tubular body made of stainless steel, for example, and also serves as a negative electrode terminal. The sealing body 4 made of, for example, stainless steel having the outer peripheral edge 3 and the slanted portion 2 is formed by placing the slanted portion 2 of the sealing body 4 on the upper surface of the upper opening of the outer can 1 and gently pressing the upper portion from the outside with a jig. Thus, the upper surface of the upper opening of the outer can 1 and the outer peripheral edge 3 of the sealing body are easily and abuttingly fitted to the upper surface of the outer can 1, so that the outer peripheral edge 3 and the outer can 4 are
Laser welding is applied to the contact portion with the upper surface of the upper opening of the above, so that the outer can 1 is securely joined and the sufficient airtightness is maintained. A hole 7 is opened near the center of the sealing body 4. For example, the positive electrode terminal 9 made of stainless steel is attached to the hole 7 by a hermetic seal through the glass insulating material 8 so that both ends of the positive electrode terminal 9 project from the upper and lower surfaces of the sealing body 4, and serves as a negative electrode terminal. 1 and the positive electrode terminal 9 are insulated.

For example, a circular hole 10 is opened in the portion of the sealing body 4 apart from the hole 7. For example, the rectangular thin film 5 is hermetically attached to the inner surface of the sealing body 4 by laser welding so as to cover the hole 10.
The groove 6 is provided at a position corresponding to the hole 10 and has, for example, a U-shape. The groove 6 is formed by pressing the thin film 5 with a punch having the same shape as the groove 6 or etching the thin film 5. The bottom of the groove 6 functions as a valve membrane 11. A safety valve mechanism 12 is formed from the hole 10 and the thin film 5 having the valve film 11 formed at the bottom thereof by the groove 6 provided at a position corresponding to the hole 10.

With this structure, by fitting the outer peripheral edge 3 and the sealing body 4 having the inclined portion 2 into the outer can 1,
The outer peripheral edge 3 of the sealing body 4 is brought into contact with the inner surface of the upper opening of the outer can 1 using the inclined portion 2. As a result, good welding can be achieved by laser welding the abutting portion between the outer peripheral edge 3 of the sealing body 4 and the inner surface of the upper opening of the outer can 1, thus improving the airtightness of the battery. Can be improved. In addition, the sealing body 4 is always used without depending on the inner diameter of the outer can 1 manufactured by deep drawing.
Since the slanted portion 2 is fitted into the outer can 1 at a fixed position, the total height of the battery can be kept constant.

Further, a hole 10 opened in the sealing body 4.
And the thin film 5 which is airtightly attached to the inner surface of the sealing body 4 by laser welding and has the valve membrane 11 formed at the bottom thereof by the groove 6 provided at a position corresponding to the hole 10. By providing the safety valve mechanism 12 in the battery, an abnormal current flows due to a short circuit due to overcharge or misuse, the temperature inside the battery rises, and the electrolyte of the power generation element housed in the outer can 1 Is disassembled,
When gas is generated and the internal pressure of the outer can 1 rises, the gas does not escape to the outside because the airtightness of the battery is high, and the thin film 5 of the safety valve mechanism 12 formed in the sealing body 4 does not leak. Pressure can be applied to the valve membrane 11 and the valve membrane 11 can be reliably broken by the pressure (operating pressure) at a predetermined pressure. As a result, it is possible to prevent the battery outer can from being ruptured or deformed due to the excessive increase in the battery internal pressure, and it is possible to obtain a highly safe lithium ion secondary battery.

In the practical example, the slanted portion 2 of the sealing body 4 is provided on the two short sides of the sealing body 4, but the slanted portion 2 is, for example, as shown in FIG. It is also possible to provide it on a part of the two longitudinal surfaces of the body 4 or on the entire two longitudinal surfaces. Further, the present invention can be applied not only to a bottomed rectangular tubular body but also to other polygonal shapes such as a triangular shape to an octagonal shape or an elliptic shape in accordance with the gist of the present invention. included.

[0020]

The present invention is embodied in the form described above and has the following effects. According to the present invention, it is possible to provide a lithium-ion secondary battery having excellent airtightness, capable of keeping the total height of the battery constant, and having improved safety.

[Brief description of drawings]

FIG. 1 is a perspective view of a sealing body of a prismatic lithium ion secondary battery of the present invention.

FIG. 2 is a sectional view of a sealing body of a prismatic lithium ion secondary battery of the present invention.

FIG. 3 is a perspective view of a sealing body of the present invention.

FIG. 4 is a perspective view of a sealing body of a conventional lithium-ion secondary battery.

FIG. 5 is a cross-sectional view of the sealing body of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Battery outer can 2 Sloped part 3 Outer peripheral edge 4 Sealing body 5 Thin film 6 Groove 7 Hole 8 Glass insulating material 9 Positive electrode terminal 10 Hole 11 Valve membrane 12 Safety valve mechanism 21 Battery outer can 22 Sealing body 23 Thin film 24 Groove 25 Glass insulating material 26 positive electrode terminal 27 hole 28 hole

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tsugio Sakai 1-8-1, Nakase, Mihama-ku, Chiba-shi, Chiba Inside Seiko Electronic Industries Co., Ltd. (72) Inventor Kensuke Tahara 1-8, Nakase, Mihama-ku, Chiba-shi, Chiba Address Seiko Electronics Industry Co., Ltd.

Claims (5)

[Claims] 1. An outer can (1) having a bottomed rectangular tubular body and accommodating a power generating element composed of a positive electrode, a negative electrode, and an electrolyte, and the outer casing (1) fitted to the inner surface of an upper opening of the outer can. A sealed battery having an inclined portion (2) on a part of a side surface of an outer peripheral portion of a sealing body (4) that abuts an inner surface of an upper opening portion of a can (1). 2. The sealed battery according to claim 1, wherein the sealing body (4) has inclined portions (2) on two short surfaces. 3. The sealed battery according to claim 1, wherein the sealing body (4) has a short surface (2) and an inclined portion (2) at a corner where the short surface (2) and the long surface (2) intersect. 4. The sealed battery according to claim 1, wherein the sealing body (4) has inclined portions (2) over the entire two short sides and the two long sides. 5. Sealing comprising a step of forming an inclined portion (2) on a part of a side surface of an outer peripheral portion of the sealing body (4), and a step of laser-welding the sealing body (4) and the outer can (1). Battery manufacturing method.