JP2003007266A - Sealing structure for electrode body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To exhaust gas outside generated inside a sealed body in which an electrode body is sealed and suppress leak, age of an electrolyte. SOLUTION: In the sealed body 30, resin-jointed members 36a, 36b are arranged in metal members 32a, 32b, the metal member 32a and the metal member 32b are jointed between edge parts 34a, 34b (metal-to-metal jointing) and between the jointing members 36a, 36b (resin-to-resin jointing). As a result, since the jointing strength between the edge parts 34a, 34b is measured about 1/10 of that between the jointing members 36a, 36b, gas generated inside the sealed body 30 can suitably be exhausted from the jointing part between the jointing members 36a, 36b. The jointing strength between the edge parts 34a, 34b is strong because of the metal-to-metal jointing. As a result, leakage of the electrolyte can be suppressed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealing structure for an electrode body, and more particularly to a structure for sealing an electrode body formed by stacking a positive electrode body, a separator and a negative electrode body with the sealing body.

[0002]

2. Description of the Related Art Conventionally, as a structure for sealing such an electrode body, there has been a structure in which an electrode body impregnated with an electrolytic solution is sealed in a bag-like sealing body by joining edges of a laminate film. It has been proposed (Japanese Patent Laid-Open No. 10-294097, etc.). In a battery using such a sealing structure, a portion having weak bonding strength is provided in a part of the bonding portion of the laminate film, so that decomposition gas of the electrolytic solution generated in the sealed body is discharged.

[0003]

However, in the conventional sealing structure, the sealing body is made of a laminated film,
Since the main bonding is between the laminated films, the bonding strength is weak overall. Therefore, electrolyte leakage may occur from the joint.

The present invention has been made to solve the above-mentioned problems, and provides a sealing structure in which gas generated in the sealed body in which the electrode body is sealed can be discharged to the outside and at the same time leakage of the electrolytic solution is suppressed. The purpose is to provide.

[0005]

A first electrode body sealing structure of the present invention is a structure in which an electrode body formed by laminating a positive electrode body, a separator and a negative electrode body is sealed with a sealing body, The sealing body is formed into a bag shape by joining edges of two metal members to each other, and each metal member has a joining strength when joined to a member made of the same material. A joining member made of a material weaker than the joining strength, joining the two metal members, joining the metal members, and joining strength between the joining members weaker than the joining strength between the metal members It is characterized by performing by joining.

In the first electrode body sealing structure of the present invention, a joining member is provided on two metallic members forming the sealing body, and the joining of the two metallic members is performed by joining the metallic members to each other. Then, the joining strength between the metallic members is weaker than the joining strength between the metallic members. Therefore, the gas generated in the sealed body can be released to the outside from the portion where the joining members are joined. Further, the joining strength of the portion where the metal members are joined is stronger than the joining strength when joining the resin members such as the laminate film. As a result, leakage of the electrolytic solution can be suppressed by the sealing structure using the laminated film.

A second electrode body sealing structure of the present invention is a structure for sealing an electrode body in which a positive electrode body, a separator and a negative electrode body are laminated with a sealing body, wherein the sealing body is The two metal members are joined together at their edges to form a bag, and at least one of the metal members has a joining strength when joined to the other metal member. Providing a joining member made of a material weaker in strength, joining the two metal members, joining the metal members together,
It is characterized in that the joining is performed by joining the metal member and the joining member, the joining strength of which is weaker than the joining strength of the metal members.

In the second electrode body sealing structure of the present invention, a joining member is provided on at least one of the two metallic members forming the encapsulating body, and the joining of these two metallic members is performed by the metallic member. The joining is performed by mutual joining and the joining between the metallic member and the joining member, the joining strength of which is weaker than the joining strength of the metallic members. Therefore, the gas generated in the sealed body can be discharged to the outside from the joint between the metal member and the joint member. In addition, since the joining strength between the metallic members is stronger than that between the laminated films and the like, leakage of the electrolytic solution can be suppressed by the sealing structure using the laminated film.

In the electrode body sealing structure of the present invention, it is preferable that the joining member is made of resin.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention (hereinafter referred to as embodiments) will be described below with reference to the drawings. In each drawing, the same members or members having the same function are designated by the same reference numerals, and the description thereof will be omitted.

FIG. 1 is a perspective view showing a structure in which the electrode body 10 of the lithium ion secondary battery of this embodiment is sealed with a sealing body 30, and FIG. 2 is a sectional view taken along the line AA in FIG. 3 and FIG. 3 shows the components forming the electrode body 10 and the sealing body 30.
FIG. 3 is an exploded view showing the parts constituting the.

As shown in FIG. 3, the electrode body 10 includes a positive electrode body 12 provided with a positive electrode terminal 12a and forming a positive electrode, and a negative electrode body 14 provided with a negative electrode terminal 14a and forming a negative electrode.
A separator 16 which is made of polypropylene and has a thickness of [μm] and which isolates the positive electrode body 12 and the negative electrode body 14 from each other and prevents a short circuit due to contact is repeatedly laminated, and has a battery function by being impregnated with a predetermined electrolytic solution. There is. The predetermined electrolytic solution is, for example, 1 mol / l in a solvent containing diethyl carbonate and ethylene carbonate in a ratio of 7: 3.
This is a solution of LiPF ₆ of.

Each positive electrode body 12 has a thickness of 85 [μm], which is formed by applying a positive electrode active material such as LiCoO _{2 on} both sides of an aluminum foil having a thickness of 25 [μm] by a comma or die coater method, drying and then pressing. The two edge portions 12b are electrically connected to each other in the electrode body 10 by being joined to each other.

The positive electrode terminal 12a is made of aluminum and is attached to the positive electrode body 12 so as to extend to the outside of the sealing body 30, and electrically connects the parts outside the sealing body 30 and the positive electrode body 12. To do. The positive electrode terminal 12a has a surface coated with a resin or a rubber material (not shown) so as to be electrically insulated from the sealing body 30.

Each negative electrode body 14 has a thickness of 80 [μm], which is obtained by applying a negative electrode active material such as graphite carbon on both sides of a copper foil having a thickness of 30 [μm] by a comma or die coater method, drying and applying the material. Each negative electrode body 14 is electrically connected in the electrode body 10 by joining the edge portion 12b of each positive electrode body 12 and the edge portion 14b on the side different from each other.

The negative electrode terminal 14a is made of copper and has a sealing body 3
It is attached to the negative electrode body 14 so as to extend to the outside of 0, and electrically connects the component outside the sealing body 30 and the negative electrode body 14. The negative electrode terminal 14a has a surface coated with a resin or a rubber material (not shown) so as to be electrically insulated from the sealing body 30.

The sealing body 30 is composed of metal members 32a and 32b made of aluminum. Metal member 32a
The edge 34a of the metal member 32b and the edge 34b of the metal member 32b are
Joining members 36a and 36b made of resin such as polypropylene and polyethylene are provided. Metal member 32
Although a and 32b are plate-shaped members before joining as shown in FIG. 3, the electrode body 10 is sandwiched between the edge portions 34a and 34b.
Are welded together and the joining member 36a and the joining member 36b are welded together to form a bag-like shape as shown in FIGS.

As described above, in the sealing body 30, the metal member 32a and the metal member 32b are joined to each other at the edge portions 34a,
Bonding between 34b (bonding between metals) and bonding members 36a, 3
6b (joining between resins), the joining strength between the joining members 36a and 36b is the same as that of the edges 34a and 34b.
It is about 1/10 of the joint strength between b. As a result, when some gas such as a decomposition gas of the electrolytic solution is generated in the sealing body 30 and the pressure in the sealing body 30 rises, the joining portion between the joining members 36a and 36b joins the edge portions 34a and 34b. Since it breaks earlier than the part, the gas inside can be suitably discharged. Further, the bonding strength between the edge portions 34a and 34b is stronger than the bonding strength when resin-made materials such as a laminated film are bonded to each other because the bonding is between metals. As a result, leakage of the electrolytic solution can be suppressed by the sealing structure using the laminate film for the entire sealing body. In addition, joining of metal members is performed by welding (including friction welding),
Ultrasonic welding or the like can be applied, and bonding between resins can be heat welding or the like. In some cases, it is possible to use an adhesive.

The joining members 36a and 36b of this embodiment are
Although resin is used as the material, it may be made of another material such that the joining strength when joining the joining members 36a and 36b is weaker than the joining strength between the edge portions 34a and 34b.

The joining members 36a and 36b of this embodiment are
Although provided on each of the metal members 32a and 32b,
It may be provided on one of the metal members 32a and 32b. For example, the joining member is provided only on the metal member 32a, the joining of the metal members 32a and 32b is performed between the edges 34a and 34b, and the joining member and the metal member 32 are provided on the metal member 32a.
and the edges 34a, 3
If the joining member is made of a material such that the joining strength between the joining member and the metal member 32b is weaker than the joining strength between the 2b, the inside of the sealing body 30 from the joining portion between the joining member and the metal member 32b. The gas generated in can be discharged.

In this embodiment, the metal members 32a, 32
Although one joining member is provided for each of b, a plurality of joining members may be provided and a plurality of portions having weak joining strength may be provided. In this case, although the overall bonding strength is weakened, the decomposition gas can be appropriately discharged.

[0022]

In the electrode body sealing structure of the present invention, the joining member is provided on the two metal members forming the sealing body, and the joining of the two metal members is performed by joining the metal members to each other. The joining strength between the metallic members is weaker than the joining strength between the metallic members. Therefore, the gas generated in the sealed body can be released to the outside from the portion where the joining members are joined. Further, the joining strength of the portion where the metal members are joined is stronger than the joining strength when joining the resin members such as the laminate film. As a result, leakage of the electrolytic solution can be suppressed by the sealing structure using the laminated film.

[Brief description of drawings]

FIG. 1 is a perspective view showing a structure in which an electrode body 10 of a lithium ion secondary battery of this embodiment is sealed with a sealing body 30.

FIG. 2 is a cross-sectional view taken along the line AA in FIG.

FIG. 3 is an exploded view showing components forming the electrode body 10 and components forming the sealing body 30.

[Explanation of symbols]

10 electrode body, 30 sealing body, 32a, 32b metal member, 34a, 34b edge portion, 36a, 36b joining member.

Claims (4)

[Claims] 1. A structure in which an electrode body formed by stacking a positive electrode body, a separator and a negative electrode body is sealed with a sealing body, wherein the sealing body joins edges of two metal members to each other. It is formed in a bag shape, each of the metal members is provided with a joining member made of a material whose joining strength when joined with members of the same material is weaker than the joining strength between the metallic members, and the two metallic members. A sealing structure for an electrode body, wherein members are joined by joining the metal members together and joining the joining members having a joining strength weaker than a joining strength between the metal members. 2. A structure in which an electrode body formed by laminating a positive electrode body, a separator and a negative electrode body is sealed with a sealing body, wherein the sealing body joins edges of two metal members to each other. It is formed in a bag shape, and at least one of the metal members is provided with a joining member made of a material whose joining strength when joined to the other metal member is weaker than the joining strength between the metal members, It is characterized in that the joining of the two metallic members is performed by joining the metallic members together and joining the metallic member and the joining member whose joining strength is weaker than the joining strength between the metallic members. Electrode body sealing structure. 3. The sealing structure for an electrode body according to claim 1, wherein the joining member is made of resin. 4. The method according to claim 3, wherein the joining of the metal members is either welding or ultrasonic welding, and the joining of the metal member and the joining member or the joining of the joining members is heat welding. Electrode body sealing structure.