JP2005071673A - Battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly reliable battery by using a container made of a film. <P>SOLUTION: The battery has unit electrode bodies 1a and 1b which are power generating elements and a sealing film 5 which demarcates for respective unit electrode bodies 1a, 1b a sealing space for sealing airtightly electrolytes contained in the unit electrode bodies 1a and 1b. The sealing space housing the unit electrode bodies 1a and 1b is demarcated by the sealing film 5, thereby the sealing space is connected continuously and the exposure of the pasting part of the sealing film 5 can be suppressed to the minimum and the permeation of moisture or the like can be suppressed. In short, the unit electrode bodies 1a and 1b are sealed in lump sum by the sealing film 5. Therefore, compared with a conventional battery in which each of the unit electrode body is sealed airtightly separately by one sealing film, the jointing face of the sealing films is not exposed to the outside directly at the adjoining part with each unit electrode body, and the permeation of moisture can be suppressed. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a battery, and more particularly to a non-aqueous electrolyte battery.

As a container for hermetically sealing an electrode body which is a power generation element of a battery, a metal one, a film one, etc. are known. Patent Documents 1 and 2 can be exemplified as a battery having a film container. By using a film container, weight reduction and cost reduction can be achieved. As the film, a heat-weldable film, for example, a laminated film in which an appropriate kind of film is bonded can be used.
JP 2000-138040 A JP 2002-313348 A

  However, since the film container is sealed by heat sealing of the resin, there is a problem that moisture and the like are easily transmitted as compared with the metal container, and the reliability is not sufficient.

  The present invention has been made in view of the above circumstances, and an object to be solved is to provide a highly reliable battery.

As a result of intensive studies conducted by the present inventors for the purpose of solving the above-mentioned problems, the inventors have arrived at the following invention. That is, the battery of the present invention includes a plurality of unit electrode bodies that are power generation elements,
And a sealing film that seals a sealing space for hermetically sealing the electrolyte contained in the unit electrode body for each unit electrode body (Claim 1).

  As described above, a laminate film or the like is often employed as the sealing film. Laminate films exhibit their intended performance by bonding multiple types of films in the thickness direction. For example, moisture permeability is suppressed by laminating a highly barrier film (barrier layer) such as an aluminum foil in a laminate film. The innermost layer portion on the unit electrode body side of the laminate film has a film made of a material preferable for bonding (for example, heat welding) between the films. Further, since the innermost layer portion is also a surface directly in contact with the unit electrode body, it is made of a chemically and physically stable material. For example, polypropylene.

  In a battery using a conventional film container, permeation of problematic water or the like does not proceed through the barrier layer, but often proceeds through a bonded portion between the innermost layer portions. Therefore, by confining the sealing space containing the plurality of unit electrode bodies with the sealing film, the sealing space is continuously connected, thereby minimizing the exposure of the bonding portion of the sealing film. And the transmission of moisture and the like can be suppressed.

  That is, each unit electrode is compared with a conventional battery in which a plurality of unit electrode bodies are collectively sealed with a sealing film, and each unit electrode body is individually hermetically sealed with one sealing film. The bonding surface of the sealing film does not directly touch the outside air at the portion adjacent to the body, and moisture transmission can be suppressed. In the present specification, the “unit electrode body” is a member of a minimum unit that operates as a power generation element of a battery, and is a member that can be operated as it is or in a certain container.

  By the way, since the battery using the conventional sealing film uses a flexible film, there exists a problem that positioning with a unit electrode body and the film which comprises a container is difficult compared with metal containers. In the battery of the present invention, electrical bonding between adjacent unit electrode bodies can be performed before sealing with a sealing film, and a plurality of processes with high productivity can be performed and positioning can be improved. It has a special effect.

  The sealing film is composed of one heat-sealing film that is folded in two or two heat-sealing films that are bonded together, so that the exposure of the bonding portion of the sealing film is minimized (for example, the periphery) Part only) (Claim 2).

  Moreover, it is preferable to have a connecting member that electrically connects the unit electrode bodies in a predetermined combination and is hermetically sealed with the sealing film. When sealed with a sealing film for each unit electrode body as in a conventional battery, an electrode terminal is provided so as to communicate between the inside and outside of the sealing film, and the electrical connection between the unit electrode bodies is established by connecting the electrode terminals. Secure connection. By adopting a connecting member hermetically sealed in the sealing film as a member for electrical connection between these unit electrode bodies, moisture permeation at a portion through which the electrode terminal in the conventional battery penetrates can be suppressed. Furthermore, also in terms of safety, there is an accompanying effect that the exposed portion of the electrical connection portion between the unit electrode bodies can be reduced.

  Furthermore, it is preferable to have a gas discharge member that can communicate between the inside and the outside of the sealed space and discharge gas generated during charging and discharging. Furthermore, it is preferable that the gas discharge member also serves as an electrolyte injection port for injecting an electrolyte into the sealed space.

  The battery of the present invention will be described in further detail. The battery of this embodiment is not particularly limited, but is preferably a non-aqueous electrolyte battery. This is because the performance of the nonaqueous battery deteriorates due to the mixing of water, but the battery can reduce the intrusion of moisture and the like from the outside.

(Constitution)
This battery has a unit electrode body, a sealing film, and a member selected as necessary. Examples of the member selected as necessary include a connection member, a gas release member, and an electrolyte solution inlet. The unit electrode body and the connection member are sealed with a sealing film.

  The unit electrode body is a power generation element of the battery. In this embodiment, the case where there are two unit electrode bodies will be described. However, the present invention is also applicable to a case where there are three or more unit electrode bodies. The unit electrode body is not particularly limited, but in this embodiment, a non-aqueous electrolyte is used for a belt-shaped positive electrode and a negative electrode laminated with sheet-like separators or a laminated positive / negative electrode wound. It is impregnated. The shape of the unit electrode body is not particularly limited, but is preferably a thin rectangular parallelepiped from the viewpoint of improving the energy volume density. The positive and negative electrodes each contain an active material selected according to the type of battery employed. In a lithium secondary battery, it is common to use a lithium-transition metal composite oxide for the positive electrode and a carbon-based material for the negative electrode. The separator can be a porous film made of polyolefin or the like. Examples of the non-aqueous electrolyte include a non-aqueous solvent such as ethylene carbonate and diethyl carbonate in which an electrolyte made of a lithium salt such as lithium hexafluoride is dissolved. Instead of the separator and the non-aqueous electrolyte, a gel electrolyte in which a gelling agent is dissolved in the non-aqueous electrolyte to form a gel can also be used.

  The connecting member is a member that electrically connects the unit electrode bodies. The unit electrode body can be directly connected to the positive and negative current collectors, or can be connected to the electrode of the unit electrode body.

  The sealing film defines a sealing space for hermetically sealing each unit electrode body. The sealing film completely hermetically seals the unit electrode body and the like. As a result, it is possible to use a minimum member (for example, an electrode for exchanging electric power between the battery and the outside) to communicate the inside and outside of the sealed space. The sealing film is preferably composed of one heat-sealing film folded in two or two heat-sealing films bonded together. The sealing space is determined by the size of the unit electrode body to be sealed. The sealing film preferably has a low moisture permeation. Moreover, the thing excellent in the chemical and physical stability with respect to the atmosphere inside a battery is preferable. And what was excellent in heat weldability is preferable. For example, a general laminate film can be employed.

  The arrangement of the two unit electrode bodies is not particularly limited, but it is preferable to arrange them in the direction in which the thickness is reduced because of the ease of sealing with the sealing film. The arrangement of three or more unit electrode bodies is not particularly limited. For example, they can be arranged continuously in a one-dimensional direction, or can be arranged continuously so as to expand in a two-dimensional direction and further in a three-dimensional direction.

  The gas releasing member and the electrolyte solution inlet can be shared. That is, it can be used as a gas releasing member by sealing the opening of the member (electrolyte inlet) used for injecting the electrolyte with an appropriate means. For example, by sealing the opening of the electrolyte injection port, the gas pressure in the sealed space can be externally applied in an emergency, etc., so that the gas can be released at an appropriate gas pressure. Can escape. The electrolyte inlet can be sealed with a sealing film or the like. A cylindrical member is mentioned as a preferable form as a gas discharge member and an electrolyte solution injection port. Gas and electrolyte are exchanged through the cylindrical portion of the cylindrical member.

(Production method)
Although the manufacturing method of this battery is not specifically limited, a specific example is given below. First, a unit electrode body containing no electrolytic solution is formed. About the unit electrode body used for one battery, the interval is electrically connected by a connection member. The sealing film is formed by bending a single heat-sealing film or sandwiching it between two heat-sealing films. Each of the heat-sealing films is a sealing portion where a unit electrode body is disposed. A depression constituting the stop space is formed in advance by a press or the like.

  A unit electrode body is disposed in a recess formed in one sealing film. Thereafter, the unit electrode body is held between the other sealing films and heat-sealed by ultrasonic welding or the like. The peripheral portion of the unit electrode body and the surface portion of the connecting member are sufficiently fused so that the electrolyte does not leak during heat fusion. The unit electrode body and the connection member are completely hermetically sealed with a sealing film.

  An electrolyte injection port that also serves as a gas releasing member is provided at the same time as heat fusion. After injecting the electrolyte from the electrolyte inlet, the opening of the electrolyte inlet is sealed. The electrolyte injection port with the opening sealed acts as a gas release member in an emergency or the like.

(Example 1)
In this example, an electrode body of a lithium secondary battery is employed as the unit electrode body, and a laminate film is employed as the sealing film. As shown in FIG. 1, the two unit electrode bodies 1 a and 1 b are hermetically sealed with a sealing film 5. FIG. 1 shows a state before the unit electrode bodies 1 a and 1 b and other components are sealed with the sealing film 5. The unit electrode bodies 1a and 1b are obtained by stacking and winding strip-shaped positive and negative electrodes and a separator. The unit electrode body 1a has a positive electrode terminal 2a and a negative electrode terminal 3a. The unit electrode body 1b has a positive terminal 2b and a negative terminal 3b. The negative electrode terminal 3a and the positive electrode terminal 2b are directly joined and used as a connection member.

  The sealing film 5 is composed of a single heat-sealing film. A sealed space in which the unit electrode bodies 1a and 1b are disposed in advance is formed by pressing. The sealing space formed in the sealing film 5 is formed in half on both surfaces of the unit electrode bodies 1a and 1b.

  The inside and outside of the sealing space are hermetically sealed by bonding the sealing film 5. Gas release members 4a and 4b are provided in the sealed space and communicate with the inside and outside of the sealed space. The gas release members 4a and 4b also serve as an electrolyte injection port.

  A battery in which the unit electrode bodies 1a and 1b are completely sealed by the sealing film 5 is shown in FIGS. The sealing film 5 is sealed by ultrasonic welding. An electrolytic solution is injected into the sealed space through the gas releasing members 4a and 4b communicating with the inside and outside of the sealed space.

  After injecting the electrolytic solution, the openings of the gas releasing members 4a and 4b are sealed. As shown in FIG. 5, the opening is sealed by joining a part of the sealing film that connects the gas release members 4 a and 4 b and the sealing space. Sealing of the opening is joined only in a small area of the sealing film so that the opening is peeled off when the gas pressure in the sealing space exceeds a predetermined value. Sealing of the openings of the gas releasing members 4a and 4b is preferably performed after conditioning the battery.

  The connection member composed of the positive electrode terminal 2b and the negative electrode terminal 3a is joined by welding, and is completely sealed by the sealing film 5 as shown in FIG. Therefore, there is little possibility that the electrolyte solution leaks or moisture enters from the gap. In particular, there is very little risk of moisture entering from the outside.

(Modification)
The battery of this modification is shown in FIG. The battery has substantially the same configuration as that of the battery of Example 1 except that the four unit electrode bodies 10a, 10b, 10c, and 10d are used. The four unit electrode bodies 10a, 10b, 10c and 10d are arranged in a square shape and are connected in series in this order. Each unit electrode body 10 a, 10 b, 10 c, and 10 d is disposed in a sealed space partitioned by a sealing film 50.

  The unit electrode bodies 10a, 10b, 10c and 10d have positive terminals 20a, 20b, 20c and 20d and negative terminals 30a, 30b, 30c and 30d, respectively. The positive electrode terminal 20a of the unit electrode body 10a and the negative electrode terminal 30d of the unit electrode body 10d are extended to the outside of the sealed space and function as a positive electrode and a negative electrode of the battery. The unit electrode bodies 10a and 10b are connected by a connecting member connecting the negative electrode terminal 30a and the positive electrode terminal 20b, and the unit electrode bodies 10b and 10c are connected by a connecting member connecting the negative electrode terminal 30b and the positive electrode terminal 20c. The unit electrode bodies 10c and 10d are connected by a connecting member connecting the negative electrode terminal 30c and the positive electrode terminal 20d.

  After sealing each unit electrode body 10a, 10b, 10c, and 10d with the sealing film 50, electrolyte solution is inject | poured through the gas discharge members 40a and 40d. The unit electrode bodies 10a and 10b and the unit electrode bodies 10c and 10d are not completely sealed, and the electrolyte injected into the sealed space in which the unit electrode bodies 10a and 10d are disposed is unit electrode bodies. It is also injected into 10b and 10c. After completely injecting the electrolytic solution, the sealing film 50 is completely joined and sealed between the gas releasing members 40a and 40d, the unit electrode bodies 10a and 10b, and the unit electrode bodies 10d and 10c.

It is the schematic which showed the mode of the assembly of the battery of an Example. It is a schematic perspective view of the battery of an Example. It is the schematic seen from the upper surface of the battery of an Example. It is the schematic seen from the front of the battery of an Example. It is the cross-sectional schematic of the gas emission member vicinity of the battery of an Example. (VV sectional view of FIG. 4) It is the cross-sectional schematic of the connection member vicinity of the battery of an Example. (VI-VI sectional view of FIG. 4) It is the schematic seen from the front of the battery of an Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 10 ... Unit electrode body 2, 20 ... Positive electrode terminal 3, 30 ... Negative electrode terminal 4, 40 ... Gas release member 5, 50 ... Sealing film

Claims (5)

A plurality of unit electrode bodies that are power generation elements,
A battery comprising: a sealing film that partitions a sealing space for hermetically sealing an electrolyte contained in the unit electrode body for each unit electrode body.   2. The battery according to claim 1, wherein the sealing film is composed of one heat-sealing film folded in two or two heat-sealing films bonded together.   The battery according to claim 1, further comprising a connection member that is electrically connected between the unit electrode bodies in a predetermined combination and is hermetically sealed with the sealing film.   The battery according to any one of claims 1 to 3, further comprising a gas discharge member capable of communicating between the inside and outside of the sealed space and capable of discharging a gas generated during charging and discharging. The battery according to claim 1, wherein the gas discharge member also serves as an electrolyte injection port for injecting an electrolyte into the sealed space.

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