JP2001084973A - Sealed battery and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sealed battery of which armoring can and lid body are formed of a resin and which allows their jointing by a laser beam to be carried out, without using a high-output laser device. SOLUTION: This sealed battery is provided with an armoring can 1, made of a thermoplastic resin having an opening, a generation element 3 received in the exterior can 1 and having a positive and negative electrodes facing each other and sandwiching a separator, a lid body 2 made of a thermoplastic resin jointed to the opening of the exterior can 1, a positive electrode terminal 11 and negative electrode terminal 12 mounted to the lid body 2 and electrically connected to the positive electrode and negative electrode of the generation element 3, respectively, and an electrolyte injection hole 7 formed on the lid body 2 for injecting the electrolyte into the exterior can 1. Either one of the exterior can 1 and the lid body 2 is formed of a thermoplastic resin, having transmittance with respect to a laser beam, the other is formed of a thermoplastic resin containing a material having absorbency for a laser beam, and the lid body 2 is mounted to the exterior can 1 by laser welding.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealed battery provided with an outer can and a lid mainly composed of a thermoplastic resin, and a method of manufacturing the same.

[0002]

2. Description of the Related Art Demand for sealed secondary batteries such as lithium ion batteries is growing, mainly for portable information devices. These batteries have an outer can made of metal such as iron, stainless steel, and aluminum alloy. The outer can is usually formed by multi-stage drawing, and the lid is joined thereto by laser welding or caulking. In particular, when the outer can is made of an aluminum alloy, sufficient joining cannot be obtained by caulking, so joining by laser welding is employed. In the case of a rectangular lithium ion secondary battery, the electrolyte is usually injected through an injection hole having a diameter of about 1 mm, and the injection hole is sealed by laser welding after the injection.

[0003] Metal has a high melting point and high thermal conductivity.
As a laser used for welding, a high-output laser that oscillates in pulses with an average output of 300 W or more and a peak output of 10 kW or more is required.

[0004]

As described above, since the metal outer can is formed by deep drawing, the process is generally complicated. In particular, in the case of a square outer can, molding is difficult,
Increases cost.

[0005] In addition, 3 is used for joining an outer can and a lid.
A YAG laser of 00 W or more is more expensive than a normal laser.

An object of the present invention is to provide a sealed battery in which an outer can and a lid are formed of resin, and which can be joined without using a high-power laser device, and a method of manufacturing the same. It is.

[0007]

A sealed battery according to the present invention for attaining the above object has an outer can made of a thermoplastic resin having an opening, and is housed in the outer can and sandwiched by a separator. A power generating element having a positive electrode and a negative electrode facing each other, a lid made of a thermoplastic resin joined to the opening of the outer can by welding, and attached to the lid or the outer can. A positive electrode terminal, a negative electrode terminal attached to the lid or the outer can, which is electrically connected to the negative electrode of the power generating element, and an electrolytic solution provided on the lid or the outer can, A liquid injection hole for liquid injection into the can, and one of the outer can and the lid is made of a thermoplastic resin having transparency to laser light, and the other is Use a material with absorbency Made from the non-thermoplastic resin, wherein the lid is characterized in that attached by laser welding to the outer can.

[0008] The method of manufacturing a sealed battery according to the present invention comprises:
An outer can made of a thermoplastic resin having an opening, a power generating element housed in the outer can and having a positive electrode and a negative electrode opposed to each other with a separator interposed therebetween, and a heat joined to the opening of the outer can by welding A lid made of a plastic resin, a positive electrode terminal attached to the lid or the outer can, and electrically connected to a positive electrode of the power generating element, and a negative electrode of the power generator attached to the lid or the outer can. An electrically connected negative electrode terminal, provided on the lid or the outer can, and provided with a liquid injection hole for injecting an electrolyte into the outer can, having a structure in which the liquid injection hole is closed. In the method of manufacturing a sealed battery, a lid made of a thermoplastic resin having transparency to the laser light is adhered to an opening of an outer can made of a thermoplastic resin containing a material capable of absorbing laser light. And from this lid side The laser beam is irradiated to the serial contact portion, the heating by absorption of the laser beam at the open end of the outer can, and is characterized in that the welding.

Another method of manufacturing a sealed battery according to the present invention comprises an outer can made of a thermoplastic resin having an opening, and a positive electrode and a negative electrode housed in the outer can and opposed to each other with a separator interposed therebetween. A power generating element, a lid made of a thermoplastic resin joined to the opening of the outer can by welding, and a positive electrode terminal attached to the lid or the outer can and electrically connected to a positive electrode of the power generating element. A negative electrode terminal attached to the lid or the outer can and electrically connected to the negative electrode of the power generating element, provided on the lid or the outer can, for injecting an electrolyte into the outer can. In the method for manufacturing a sealed battery having a liquid injection hole and a structure in which the liquid injection hole is closed, the laser light is transmitted to an opening of an outer can made of a thermoplastic resin having transparency to laser light. Material with absorbency Brought into close contact with the cover body made of non-thermoplastic resin, wherein said laser beam is irradiated from the outer can side to the contact portion, heated by absorbing the laser light to the lid,
It is characterized by welding.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a sealed battery according to the present invention will be described in detail.

The sealed battery includes an outer can made of a thermoplastic resin having an opening. The power generating element is housed in the outer can. This power generation element has a positive electrode and a negative electrode opposed to each other with a separator interposed therebetween. Specifically, a positive electrode and a negative electrode opposed to each other with a separator interposed therebetween are spirally wound and further flattened by further pressing, or a power generating element in which a positive electrode and a negative electrode are alternately stacked with a separator interposed therebetween is used. .

For example, in the case of a lithium ion secondary battery, the positive electrode has a structure in which a paste containing an active material such as lithium nickel oxide or lithium cobalt oxide is held on both sides of a current collector such as a thin copper plate. Have.

For example, in the case of a lithium ion secondary battery, a porous film made of a synthetic resin such as polypropylene is used as the separator.

A lid made of a thermoplastic resin is joined to the opening of the outer can by welding. The positive electrode terminal electrically connected to the positive electrode of the power generating element is attached to the lid or the outer can. The positive electrode terminal is made of, for example, aluminum or an aluminum alloy, and is directly caulked to the lid or the outer can. A negative electrode terminal electrically connected to the negative electrode of the power generating element is attached to the lid or the outer can. The negative electrode terminal is made of, for example, any of iron, stainless steel, nickel, copper, and a copper alloy, and is directly caulked to the lid or the outer can.

An injection hole for injecting the electrolyte into the outer can is provided in the lid or the outer can, and is sealed after the injection by, for example, heat welding or brazing a thermoplastic resin. Have been. As the electrolyte, for example, in the case of a lithium ion secondary battery, an electrolyte such as lithium perchlorate, lithium borofluoride, lithium hexafluoride, and lithium hexafluoride is dissolved in an organic solvent such as ethylene carbonate or propylene carbonate. What was done is used.

In the sealed battery having such a structure, one of the outer can and the lid is made of a thermoplastic resin having a laser beam transmitting property, and the other contains a material having a laser beam absorbing property. The cover is made of a thermoplastic resin, and the lid is attached to the outer can by laser welding.
Specifically, the following method can be used.

(1) A lid made of a thermoplastic resin having a laser beam transmitting property is brought into close contact with an opening of an outer can made of a thermoplastic resin containing a material having an absorptivity to a laser beam, and from the lid side. The lid is hermetically attached to the exterior can by irradiating the contact portion with laser light, absorbing the laser light at the opening end of the exterior can, heating and welding.

(2) A lid made of a thermoplastic resin containing a material capable of absorbing laser light is brought into close contact with the opening of the outer can made of a thermoplastic resin having a laser beam transmitting property, and Irradiating the contact portion with laser light from
The lid is air-tightly attached to the outer can by absorbing the laser beam, heating and welding.

Examples of the thermoplastic resin having laser light transmittance include polypropylene, polyethylene, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), vinyl chloride resin, fluorine resin, and the like.
Alternatively, a fiber-reinforced resin or the like containing these resins as main components and adding glass fibers can be used.

As the material having an absorptivity to the laser light, for example, dyes and pigments are used, and specifically, copper phthalocyanine green, carbon black and the like can be used.

The material having absorptivity to the laser light is added to the thermoplastic resin such that, for example, when a laser diode is used as the laser light, the absorption of the laser light becomes 95% or more per 1 mm. Is preferred.

The laser light is, for example, a semiconductor laser, Y
Wavelengths of 635 nm and 670 nm using an AG laser as a light source,
Those having 780 nm, 808 nm, 940 nm, and 1064 nm are used.

The above sealed battery (for example, a square sealed lithium ion secondary battery) has the structure shown in FIGS.

FIG. 1 is a top view of the secondary battery, and FIG. 2 is a sectional view of the secondary battery. The lid 2 is in contact with the periphery of the opening of the bottomed rectangular cylindrical outer can 1, and is hermetically joined by laser welding. Either the outer can 1 or the lid 2 is made of a thermoplastic resin having a laser beam transmitting property,
The other is made of a thermoplastic resin containing a material that absorbs laser light.

In the outer can 1, for example, a positive electrode and a negative electrode are laminated or spirally wound with a separator interposed therebetween.
The flattened power generating element 3 is housed therein. For example, a spacer 4 made of a synthetic resin is disposed on the power generation element 3. A positive electrode lead 5 and a negative electrode lead 6 are respectively connected to the positive electrode and the negative electrode of the power generating element 3, and the other ends of the leads 5, 6 extend through the spacer 4 to the inner surface side of the lid 2.

A liquid injection hole 7 is opened in the center of the lid 2, and an electrolyte is injected into the outer can 1 through the liquid injection hole 7. After the injection, the injection hole 7 is sealed by welding or brazing a plug 8 made of synthetic resin. Rectangular positive and negative electrode terminal holding holes 9 and 10 are opened in the left and right portions of the lid 2 with the liquid injection hole 7 interposed therebetween. The positive electrode terminal holding hole 9 has a rectangular positive terminal 1.
The other end of the positive electrode lead 5 is connected to the positive electrode terminal 11. A rectangular positive terminal 12 is crimped to the negative terminal holding hole 10, and the other end of the negative lead 6 is connected to the negative terminal 12.

According to the present invention described above, one of the outer can and the lid is made of a thermoplastic resin having a laser beam transmitting property, and the other is a thermoplastic resin containing a material having a laser beam absorbing property. It is made of resin, and the lid is attached to the outer can by laser welding, thereby ensuring airtightness and sealing at a lower cost than a conventional sealed battery using a metal outer can that is deep drawn. Type battery can be obtained.

Further, according to the present invention, a lid made of a thermoplastic resin having a laser beam transmittance is brought into close contact with an opening of an outer can made of a thermoplastic resin containing a material having an absorptivity to a laser beam, By irradiating the contact portion with laser light from the lid side, absorbing and heating the laser light at the opening end of the outer can, and welding or welding, or an outer can made of a thermoplastic resin having laser light transmittance. A lid made of a thermoplastic resin containing a material having absorptivity to laser light is brought into close contact with the opening, and a laser beam is irradiated from the exterior can side to the contact portion, and the lid absorbs the laser light. By heating and welding, the lid can be hermetically laser-welded to the outer can with a lower output laser compared to conventional sealed battery production using a metal outer can and a lid. Cost reduction It can provide a method of manufacturing a sealed battery that can be achieved.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to FIGS.

(Example) First, a glass fiber reinforced polypropylene produced by an injection molding method was applied to a wavelength of 808 nm.
An outer can 1 to which 0.2% by weight of copper phthalocyanine green having absorption in the vicinity was added was prepared.

Further, a lid 2 made of polypropylene having a liquid injection hole 7 at the center and rectangular positive and negative electrode terminal holding holes 9 and 10 on the left and right sides of the liquid injection hole 7 is prepared. Positive and negative terminals 11, 12 were crimped to the negative electrode terminal holding holes 9, 10, respectively.

Next, a positive electrode paste containing cobalt lithium and a binder is applied to both surfaces of the aluminum foil to which the leads 5 made of aluminum are connected and dried. A negative electrode paste containing graphite and a binder is applied to both surfaces of the copper foil to which the leads 6 are connected,
The power-generating element 3 was manufactured by stacking the dried negative electrode and the negative electrode in this order. Subsequently, after storing the power generating element 3 in the outer can 1, a spacer 4 made of polypropylene was set on the power generating element 3.

Next, the positive and negative electrode leads 5 and 6 of the power generating element 3 were connected to the positive and negative electrode terminals 11 and 12 of the lid 2 through the spacer 4 respectively. Subsequently, after the lid 2 is brought into contact with the periphery of the opening of the outer can 1, the wavelength 8
A continuous oscillation semiconductor laser beam having a wavelength of 08 ± 2 nm and an output of 30 to 60 W is passed through an optical fiber and has a diameter of 0.6 by a condenser lens.
The light was condensed on a spot having a diameter of about 0.8 mm, and was irradiated on the peripheral portion of the opening of the outer can 1 and the contact portion of the lid 2. At this time, the laser light passed through the lid 2 and reached the outer can 1, and was absorbed. For this reason, the input energy of the laser beam is concentrated on the periphery of the opening of the outer can 1 and the contact portion of the lid 2 so that the members 1 and 2 are efficiently joined, and the outer can 1 is
And hermetically sealed.

Next, a non-aqueous solvent-based electrolyte obtained by dissolving an electrolyte of lithium hexafluorophosphate in ethylene carbonate and methyl ethyl carbonate is injected into the outer can 1 through the injection hole 7 of the lid 2. The plug 8 made of polypropylene was inserted into the injection hole 7, and was sealed by welding to assemble the sealed rectangular lithium ion secondary battery having the structure shown in FIGS.

The obtained rectangular sealed lithium-ion secondary battery exhibits excellent charge / discharge cycle characteristics similarly to a conventional rectangular sealed lithium-ion secondary battery using an aluminum outer can and an aluminum lid. In addition, it was confirmed in a high temperature storage test that the weight was hardly reduced, the airtight reliability was high, and excellent output characteristics were obtained by maintaining the capacity. Therefore, in the rectangular sealed lithium ion secondary battery of the embodiment, the outer can and the lid were made of a synthetic resin such as polypropylene, so that the cost could be reduced.

In the above embodiment, the liquid injection hole and the positive and negative electrode terminals are provided on the lid, but either one or both of them may be provided on the outer can.

In the above embodiment, phthalocyanine is used as a green dye. However, phthalocyanine can be used as a blue dye, and monochlorophthalocyanine can be used.

Further, similar effects can be obtained by using a pigment such as carbon black as a material having an absorption characteristic for laser light.

[0039]

As described above in detail, according to the present invention, the outer can and the lid are formed of resin, and the joining thereof can be performed without using a high-power laser device. And a method of manufacturing the same.

[Brief description of the drawings]

FIG. 1 is a top view showing a rectangular sealed lithium ion secondary battery according to the present invention.

FIG. 2 is a cross-sectional view of the secondary battery of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Outer can, 2 ... Lid, 3 ... Power generation element, 7 ... Liquid injection hole, 8 ... Synthetic resin stopper, 11 ... Positive electrode terminal, 12 ... Negative electrode terminal.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) H01M 2/36 101 H01M 2/36 101A // B29K 101: 12 B29L 22:00 F term (Reference) 4F211 AA04 AA11 AA15 AA16 AA24 AA25 AH42 TA01 TC16 TJ30 TN27 5H011 AA09 CC02 DD13 DD26 EE04 FF02 FF03 GG02 GG09 HH02 JJ00 JJ25 JJ29 5H022 AA09 BB17 CC02 CC08 CC12 EE06 5H023 AA03 AS01 AS05 AS05 BB17

Claims (9)

[Claims] 1. An outer can made of a thermoplastic resin having an opening, a power generation element housed in the outer can and having a positive electrode and a negative electrode opposed to each other with a separator interposed therebetween, and welding to the opening of the outer can. A lid made of a thermoplastic resin joined by, a positive electrode terminal attached to the lid or the outer can, and electrically connected to the positive electrode of the power generating element, attached to the lid or the outer can, A negative electrode terminal electrically connected to the negative electrode of the power generating element, and a liquid injection hole provided in the lid or the outer can for injecting an electrolyte into the outer can; One of the lids is made of a thermoplastic resin having a property of transmitting laser light, and the other is made of a thermoplastic resin containing a material having an absorptivity to the laser light. Laser welding Sealed battery, characterized in that attached. 2. The thermoplastic resin is polypropylene,
2. The sealed battery according to claim 1, wherein the battery is polyethylene, polyethylene terephthalate, polybutylene terephthalate, polyvinyl chloride, or a fluororesin. 3. The material having an absorptivity to the laser light is a dye or a pigment.
Or the sealed battery according to any one of 2. 4. The sealed battery according to claim 1, wherein the positive electrode terminal is made of aluminum or an aluminum alloy, and is directly caulked to the lid or the outer can. 5. The device according to claim 1, wherein the negative electrode terminal is made of any one of iron, stainless steel, nickel, copper, and a copper alloy, and is directly caulked to the lid or the outer can. Sealed battery. 6. The sealed battery according to claim 1, wherein the injection hole of the lid is sealed by heat welding or brazing a thermoplastic resin. 7. An outer can made of a thermoplastic resin having an opening, a power generating element housed in the outer can and having a positive electrode and a negative electrode facing each other with a separator interposed therebetween, and welding to the opening of the outer can. A lid made of a thermoplastic resin joined by, a positive electrode terminal attached to the lid or the outer can, and electrically connected to the positive electrode of the power generating element, attached to the lid or the outer can, A negative electrode terminal electrically connected to a negative electrode of the power generating element; and a liquid injection hole provided on the lid or the outer can for injecting an electrolyte into the outer can. In a method of manufacturing a sealed battery having a structure in which the laser light is absorbed, an opening of an outer can made of a thermoplastic resin containing a material having absorptivity to laser light is formed from a thermoplastic resin having transparency to the laser light Close the lid, Of the laser beam is irradiated on the adhesion portion from the lid side, said heated by absorbing the laser beam at the open end of the outer can, the manufacturing method of sealed battery, characterized by welding. 8. An outer can made of a thermoplastic resin having an opening, a power generating element housed in the outer can and having a positive electrode and a negative electrode opposed to each other with a separator interposed therebetween, and welding to the opening of the outer can. A lid made of a thermoplastic resin joined by the above, attached to the lid or the outer can, a positive terminal electrically connected to a positive electrode of the power generating element, attached to the lid or the outer can, A negative electrode terminal electrically connected to a negative electrode of the power generating element; and a liquid injection hole provided on the lid or the outer can for injecting an electrolyte into the outer can. In a method of manufacturing a sealed battery having a structure in which the sealing material is closed, an opening of an outer can made of a thermoplastic resin having transparency to a laser beam is formed from a thermoplastic resin containing a material having absorptivity to the laser beam. Close the lid, The laser beam is irradiated from Kigaiso cans side to said contact portion, said heated lid said to absorb the laser light to the method of manufacturing a sealed battery, wherein the welding. 9. The method for manufacturing a sealed battery according to claim 8, wherein the liquid injection hole of the lid is sealed by heat welding or brazing a thermoplastic resin.