JP2002175799A - Sealed battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sealed battery preventing deterioration of the air tightness of a sealed part. SOLUTION: A battery housing for storing generating elements and a battery lid of the battery are made of aluminum or aluminum alloy, and an injection port for injecting a battery electrolyte is formed in the battery housing or the battery lid. A female screw is formed in the injection port, with which a male screw part formed in a plug made of aluminum or aluminum alloy is engaged. The outer end of the plug is welded to the battery housing or the battery lid by the 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 in which an injection port for injecting an electrolyte into a battery case is sealed with an injection plug.

[0002]

2. Description of the Related Art In recent years, large non-aqueous electrolyte secondary batteries have come into practical use for large capacity applications such as electric vehicles. In this nonaqueous electrolyte secondary battery, a stainless steel battery lid is also fitted into the upper end opening of a stainless steel battery case, and the periphery is welded by arc discharge from a tungsten electrode in an inert gas atmosphere. , TIG
(Tungsten Inert Gas) A battery was formed by hermetically fixing by welding.

[0003] Before welding a battery cover, a wound circular or elliptical power generating element or a laminated power generating element is provided inside a battery case in the form of a cylindrical, long cylindrical or square battery. It is stored in the case. A positive terminal and a negative terminal that are internally connected to the positive and negative electrodes of the power generating element, respectively, protrude from the upper part of the battery lid with insulation sealing. Also,
The battery lid is provided with a liquid inlet for injecting a non-aqueous electrolyte into the inside after welding with the battery case.

FIGS. 7 to 9 are partially enlarged longitudinal sectional views showing the relationship between a liquid injection port and a liquid injection plug formed in a battery lid in a conventional nonaqueous electrolyte secondary battery. 7 to 9, 2
1 is a battery cover, 22 is a liquid injection plug, 23 is a screw part, 24 is a sealant, and 25 is a welded part.

FIG. 7 shows that a female screw is formed in a liquid inlet of a battery cover 21 and a non-aqueous electrolyte is injected into a battery case.
The liquid injection plug 22 having a male screw portion is screwed into the liquid injection port, and the liquid injection port is sealed.

[0006] In this case, a flat screw is used as the injection plug,
After pouring the non-aqueous electrolyte into the battery case, the liquid inlet may be sealed by screwing a flat screw through the PP packing. The PP packing is a ring-shaped sealing material, and is compressed between the back surface of the head of the flat screw and the upper edge of the liquid inlet to close the gap.

FIG. 8 shows that a female screw is formed in the liquid inlet of the battery cover 21 and a non-aqueous electrolyte is injected into the battery case.
A sealing agent is applied to the male screw portion of the liquid injection stopper 22 and
2 was screwed into the injection port, and the injection port was sealed.

In this case, a sealing tape made of Teflon (registered trademark) may be used instead of the sealing agent. Further, the female screw portion of the liquid inlet of the battery lid 21 and the male screw portion of the liquid injection plug 22 may use tapered screws.

FIG. 9 shows a case in which a non-aqueous electrolyte is injected into a battery case, and then a screwless plug 22 having no screw is inserted into the liquid inlet, and the liquid stopper 22 and the battery cover 21 are directly welded. Is a weld.

[0010]

However, in the case where a liquid injection stopper is screwed into the liquid injection port of the battery lid and the liquid injection port is sealed, the sealing is insufficient.

[0011] Further, the seal tape and PP packing made of synthetic resin are deteriorated due to aging, and may be deteriorated in a high-temperature and high-humidity environment. Therefore, there is a problem that the electrolyte may leak.

Further, when the method of directly welding the injection plug and the battery lid is used, the heat of welding causes the electrolyte to evaporate from the inside of the battery, resulting in poor welding.

[0013] Further, as for batteries, demands for higher energy density have increased, and in order to reduce the weight, aluminum or aluminum alloy has come to be used instead of stainless steel for the material of the battery case.

However, there has been a problem that conventional TIG welding cannot be used for welding aluminum or aluminum alloy because the calorific value is too large.

The present invention has been made in view of such circumstances, and a liquid injection plug having a male screw portion is screwed into a liquid injection port.
It is an object of the present invention to provide a battery in which there is no danger that the airtightness of the sealing portion is reduced by welding between these portions by welding.

[0016]

According to a first aspect of the present invention, a battery case and a battery cover accommodating a power generating element are made of aluminum or an aluminum alloy, and a liquid for injecting an electrolyte into the battery case or the battery cover is provided. In the sealed battery having the opening formed therein, a female screw is formed in the injection opening, and a male screw portion formed in an aluminum or aluminum alloy injection plug is screwed into the injection opening, and
A space between the outer end of the injection plug and the battery case or the battery lid is welded by laser welding.

According to the first aspect of the present invention, since the male screw portion of the injection plug is screwed into the female screw of the injection port to perform high-precision welding, the injection plug is firmly fixed and the injection liquid is injected. The mouth can be reliably sealed. In addition, since the sealing is made by welding metals together without using a sealing material made of a synthetic resin or the like, there is no danger of deterioration due to aging or deterioration due to a poor environment and deterioration in airtightness.

According to a second aspect of the present invention, the battery case and the battery cover for accommodating the power generating element are made of aluminum or an aluminum alloy, and the battery case or the battery cover is formed with a liquid injection port for injecting an electrolyte. In the type battery, a nut is provided on the inside of the battery at the filling port, and a male screw portion formed on an aluminum or aluminum alloy filling plug is screwed to the nut, and the outer end of the filling plug and The battery case or the battery lid is welded by laser welding.

According to the second aspect of the present invention, even when the thickness of the battery case or the battery lid provided with the liquid inlet is small,
The liquid inlet is firmly fixed to the liquid inlet, so that the liquid inlet can be more reliably sealed.

According to a third aspect of the present invention, in a sealed battery having a nut inside the battery at the liquid inlet, a female screw is formed at the liquid inlet, and a male screw portion formed at the liquid inlet is provided at the liquid inlet. It is characterized by being screwed.

According to the third aspect of the invention, the liquid injection stopper is firmly fixed to both the liquid injection port and the nut, so that the liquid injection port can be more securely sealed.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings, taking a large non-aqueous electrolyte secondary battery as an example.

FIG. 2 is an overall perspective view showing the appearance of a large sealed non-aqueous electrolyte secondary battery. In FIG. 2, 1 is a sealed nonaqueous electrolyte secondary battery, 2 is a battery case, 3 is a battery lid,
4 is a positive electrode terminal, 5 is a negative electrode terminal, 6 is an injection port, and 7 is an injection plug.

In this sealed nonaqueous electrolyte secondary battery, an oval-shaped battery cover 3 also made of aluminum is fitted into an upper end opening of a long cylindrical battery case 2 made of aluminum.
The periphery is hermetically fixed by laser welding. A positive electrode terminal 4 and a negative electrode terminal 5 are attached to the battery cover 3, and a liquid inlet 6 for injecting a non-aqueous electrolyte into the battery is opened. Has an internal thread.

In the above sealed nonaqueous electrolyte secondary battery, when an electrolyte is injected into the battery from a liquid inlet 6 provided in the battery cover 3, a liquid stopper 7 is screwed into the liquid inlet 6. Combine. The injection plug 7 is made of aluminum.

FIG. 1 is a partially enlarged longitudinal sectional view showing a liquid injection stopper screwed into a liquid injection opening formed in a battery lid of a sealed nonaqueous electrolyte secondary battery. In FIG. 1, reference numeral 3 denotes a battery lid, 7 denotes an injection plug, 8 denotes a laser welded portion, and 10 denotes a minus groove.
A female screw is attached to the entire injection port, and the head of the injection plug 7 has a round shape.

When the injection plug 7 is screwed into the injection port, the contact portion between the injection plug 7 and the battery lid 3 is welded by laser welding. Laser welding has the advantages of high welding accuracy and extremely high welding speed. Furthermore, pulsing is possible by modulating the current. Further, since the laser light can be transmitted to a distant place via an optical fiber, handling becomes extremely easy and workability is enhanced.

As described above, the injection plug 7 and the battery lid 3 are welded and integrated by laser welding, so that the inside of the battery case can be reliably sealed. Moreover, since the injection plug 7 is welded in a state of being screwed into the injection port 3, even if it receives an external impact or the like, it is supported by the screwed portion and a load is directly applied to the welded portion. And is firmly fixed in the liquid inlet.

The shape of the injection port and the injection plug according to the present invention may be any of the shapes shown in FIGS. 3 to 6 in addition to the shape shown in FIG. FIGS. 3 to 6 are partially enlarged longitudinal sectional views showing another example of a liquid injection plug screwed into a liquid injection port formed in a battery lid of a sealed nonaqueous electrolyte secondary battery. FIG.
In FIG. 6, 3 is a battery lid, 7 is an injection plug, 8 is a laser welded portion, 9 is a portion without a screw, 10 is a minus groove, 1
1 is a nut. In FIGS. 3 to 6, the liquid injection plug 7 is screwed from the outside of the battery to the injection port. Shall be.

FIG. 3 shows an example in which a female screw is provided at a part of the liquid inlet, and FIG. 3-a shows a female screw provided on the outside of the battery at the liquid inlet. FIG. 3B shows an example in which a female screw is provided between the outside and the inside of the battery at the liquid inlet,
FIG. 3C shows an example in which a female screw is provided inside the battery at the liquid inlet. Although FIG. 3 shows an example in which the mounting position of the male screw of the liquid injection plug is adjusted to the position of the female screw of the liquid injection port, the external screw of the liquid injection plug may be mounted on the entire surface.

FIG. 4 shows an example in which the injection port and the injection plug have a shape similar to that of FIG. 1. The head of the injection plug has a pan shape in FIG. Fig. 4-
c is a flat type.

FIG. 5 shows a state in which the upper end surface of the injection plug is screwed to a position where it is flush with the upper end surface of the injection opening (outer edge surface of the battery lid).
The injection plug shows an example of a shape that is laser-welded without protruding from the battery lid, and FIG. 5-a shows a small screw in which the shape of the injection plug is entirely composed of a male thread and has no bolt head. A minus groove 10 for screwing with a screwdriver or the like is formed on the upper end surface (outer end surface). FIG. In FIG. 5C, the shape of the bolt head of the injection plug is a flat type, and a minus groove 10 for screwing with a driver or the like is formed in this head. Is what it is.

FIG. 6 shows an example in which a nut is previously provided inside the battery at the liquid inlet. FIG. 6-a shows a case where a female screw is provided on the entire liquid inlet, and FIG. 6-b shows a liquid inlet. Is provided with a female screw in the liquid inlet, and FIG. 6-c shows a case where the female screw is not provided in the liquid inlet, and the liquid tap 7 is screwed into the liquid inlet, the nut, or both the liquid inlet and the nut. It is to tighten. This shape can be used when the thickness of the battery lid is small and it is difficult to provide screws.

The shape of the head of the injection plug 7 is not limited to the shapes shown in FIGS. 1 and 3 to 6, but may be other shapes such as a pan type, a flat type, a round type, and a flat type. can do.

Further, a minus groove 10 is formed at the upper end of the injection stopper 7.
However, since it is only necessary that the liquid injection plug 7 can be screwed in, a shape with a seat, a shape with a cross hole, a shape with a hexagonal hole besides the shapes shown in FIGS. A tool groove or a tool hole of another shape such as a mold may be provided.

It should be noted that the female screw of the injection port and the injection plug 7 here are used.
Although the case where a normal parallel screw is used for the male screw portion of the above, a taper screw whose diameter becomes smaller toward the lower side can be used for these.

In the above embodiment, the case where the liquid inlet is formed in the battery cover 3 has been described. However, the present invention is not limited to the configuration using the battery cover 3, and may be formed in the battery case 2.

As described above, in the sealed nonaqueous electrolyte secondary battery of this embodiment, the injection plug 7 is screwed into the injection port and laser-welded, so that the injection plug 7 is firmly attached. The liquid inlet can be fixed and sealed. Further, when a taper screw is used for the female screw portion of the liquid injection port and the male screw portion of the liquid injection plug 7, since these can be tightened and screwed and then welded, the liquid injection plug 7 can be fixed more securely. It can be something.

In addition, since sealing is performed by welding aluminum or aluminum alloy together without using a sealing material such as a sealing tape made of synthetic resin or PP packing, deterioration during use or in an environment of high temperature and high humidity is performed. There is no danger that the airtightness is reduced by the deterioration.

Further, by using aluminum or an aluminum alloy for the material of the battery case and the battery lid, the battery is lighter in weight than a conventional battery using stainless steel, and as a result, the sealed non-aqueous electrolyte secondary battery having a high energy density is obtained. You can get a battery.

As the shape of the power generating element used in the present invention, a wound circular or elliptical shape or a laminated type can be used, and the shape of the battery case can be cylindrical, long cylindrical or square. A mold or the like can be used.

The present invention is particularly effective for a large battery having a capacity of 5 Ah or more. This is because when the battery is large, the liquid injection port and the liquid injection plug have a size that is easy to handle, and the assembling work of the battery becomes easy.

However, the present invention is not limited to a large non-aqueous electrolyte secondary battery, but can be similarly applied to other types of batteries.

[0044]

Embodiments of the present invention will be described below in detail.

Several types of sealed nonaqueous electrolyte batteries having different structures of the injection port and the injection plug were prepared, and the degree of leakage of the electrolyte was compared.

The positive electrode sheet was prepared by mixing 80 wt% of lithium cobalt oxide (LiCoO ₂ ) as an active material, 8 wt% of acetylene black as a conductive additive, and 12 wt% of polyvinylidene fluoride (PVdF) as a binder.
-Methylpyrrolidone (NMP) was added to prepare a paste, which was 42 mm wide, 480 mm long and 20 μm thick
m of an aluminum foil current collector was applied to both sides, dried at 100 ° C., and NMP was evaporated to produce the same. The obtained positive electrode sheet has a thickness of 180 μm and has a mixture layer on both surfaces of the current collector.

The negative electrode sheet is prepared by mixing 92% by weight of graphite (graphite) as an active material and 8% by weight of polyvinylidene fluoride as a binder, and mixing N-methylpyrrolidone (N
MP) to prepare a paste, which is then
m, a length of 480 mm and a thickness of 15 μm were applied to both sides of a copper foil, dried at 100 ° C., and evaporated to produce NMP.
The obtained negative electrode sheet had a thickness of 170 μm and provided a mixture layer on both surfaces of the current collector.

Lead terminals were welded to the ends of the obtained positive electrode plate and negative electrode plate, respectively. 10 thickness for positive lead terminal
A 0 μm aluminum piece was used, and a 100 μm thick nickel piece was used for the negative electrode lead terminal. As the separator, a microporous polyethylene membrane having a width of 46 mm and a thickness of 25 μm was used.

Then, the positive electrode lead terminal and the negative electrode lead terminal are both formed as winding start portions, and the positive electrode plate, the separator, the negative electrode plate, and the separator are alternately overlapped in this order, and a rectangular core of polyethylene is formed. Is wound around the power generation element in an elliptical spiral shape so that the long side is parallel to the winding center axis of the power generation element, to obtain a wound power generation element having a size of 46 × 35 × 4 mm.

This wound type power generating element has a height of 47.0 m.
m, a width of 22.2 mm and a thickness of 6.4 mm were inserted into a stainless steel case to assemble a long cylindrical battery. And
Ethylene carbonate (EC) and diethyl carbonate (DEC) are mixed at a volume ratio of 1: 1 and 1 mol / l
Of LiPF6 was injected.

Thereafter, the battery was sealed using a sealing portion having the shape shown in FIGS. Thus, eight types of sealed nonaqueous electrolyte batteries having a nominal capacity of 10 Ah were manufactured.
Here, the case where the shape of the sealing portion is shown in FIG.
FIG. 3A shows the battery of the second embodiment, FIG. 3C shows the battery of the third embodiment, FIG.
The case of -c was the battery of Example 5, the case of FIG. 7 was the battery of Comparative Example 1, the case of FIG. 8 was the battery of Comparative Example 2, and the case of FIG. 9 was the battery of Comparative Example 3.

Each of these batteries was prepared at a temperature of 25 ° C.
At a constant current / constant voltage of 400 mA / 4.1 V
The battery was charged for 400 hours and discharged to 2.75 V at 400 mA. These batteries were kept at 50 ° C. for 48 hours, and thereafter, leakage of the electrolyte from each battery was observed. Table 1 summarizes the results. In Table 1, the number of each battery is shown.

[0053]

[Table 1]

From the results shown in Table 1, it was found that the batteries of Examples 1 to 5 of the present invention did not have any defects during the sealing process and did not leak electrolyte, In the batteries of Comparative Examples 1 and 2 having the same shape as the conventional battery,
There were no defects during the sealing process, but a considerable number of electrolyte leaks were seen. Further, in the battery of Comparative Example 3, there were many defects at the time of sealing, and leakage of the electrolyte was observed.

[0055]

As is apparent from the above description, according to the battery of the present invention, the male screw portion of the liquid injection stopper is screwed into the female screw of the liquid injection port, or the nut is provided inside the battery, and The liquid stopper and the nut are screwed together, and the liquid stopper and the battery lid or the battery case are laser-welded, so that the metal can be securely sealed by welding. Therefore, it is not necessary to use a sealing material made of a synthetic resin or the like, and there is no possibility that the airtightness may be reduced during use.

Further, by using laser welding, even if the battery case or the battery lid is made of aluminum or aluminum alloy stainless steel, welding can be performed easily and reliably.

[Brief description of the drawings]

FIG. 1 is a partially enlarged longitudinal sectional view showing an embodiment of the present invention and showing an injection plug screwed into an injection port formed in a battery case of a nonaqueous electrolyte secondary battery.

FIG. 2 is an overall perspective view showing the appearance of a large non-aqueous electrolyte secondary battery.

FIG. 3 is a partially enlarged longitudinal sectional view showing an embodiment of the present invention and showing a configuration example in which a female screw is provided in a part of a liquid inlet.

FIG. 4 shows an embodiment of the present invention, in which a liquid inlet and a liquid tap are similar in shape to FIG. 1, and a partial enlarged view showing a configuration example in which the shape of the head of the liquid tap is different. Longitudinal section.

FIG. 5 is a partially enlarged longitudinal sectional view showing an embodiment of the present invention and showing a configuration example in which a liquid injection plug does not protrude from a battery lid.

FIG. 6, showing an embodiment of the present invention, is a partially enlarged longitudinal sectional view showing a configuration example in which a nut is provided in advance on the inside of a battery at a liquid inlet.

FIG. 7 is a partial enlarged longitudinal sectional view showing a conventional example, in which a liquid injection plug having a male screw portion is screwed into a liquid injection port and sealed.

FIG. 8 is a partially enlarged longitudinal sectional view showing a conventional example, in which a sealing agent is applied to a male screw portion of a liquid injection plug, and the liquid injection plug is screwed into a liquid injection port and sealed.

FIG. 9 is a partially enlarged longitudinal sectional view showing a conventional example, in which a liquid injection plug having no screw is fitted into a liquid injection port, and a liquid injection plug and a battery lid are directly welded.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sealed nonaqueous electrolyte secondary battery 2 Battery case 3, 22 Battery lid 4 Positive electrode terminal 5 Negative terminal, 6 Filling port 7, 22 Filling plug 8 Laser welded part 9 Part without screw 10 Minus groove 11 Nut 23 Screw Part 24 Sealant 25 Welded part

Claims (3)

[Claims] 1. A battery case and a battery cover accommodating a power generating element are made of aluminum or aluminum alloy,
In the sealed battery in which a liquid inlet for injecting the electrolyte into the battery case or the battery lid was formed, an internal screw was formed in the liquid inlet, and an aluminum or aluminum alloy liquid stopper was formed. A sealed battery, wherein a male screw portion is screwed into the injection port, and a gap between an outer end of the injection plug and the battery case or the battery lid is welded by laser welding. 2. A battery case and a battery cover accommodating a power generating element are made of aluminum or aluminum alloy,
In a sealed battery in which a liquid inlet for injecting an electrolytic solution into the battery case or the battery lid is formed, a nut is provided inside the battery at the liquid inlet, and a liquid stopper made of aluminum or an aluminum alloy is formed. A sealed battery, wherein a male screw portion is screwed into the nut, and a gap between an outer end of the injection plug and the battery case or the battery lid is welded by laser welding. 3. The sealed battery according to claim 2, wherein a female screw is formed in the liquid injection port, and a male screw portion formed in the liquid injection plug is screwed into the liquid injection port.