JPS61285655A - Manufacture of thin enclosed cell - Google Patents

Abstract

PURPOSE:To reduce defective welding when sealing the electrolyte injection port by making an electrolyte injection port at the circumferential section of cell cover covering the open section of cell container and welding the injection port upon injection of electrolyte while inclining the cell and never existing the electrolyte near the injection port. CONSTITUTION:Positive electrode current collector 2 comprising an expanded nickel pressure applied with positive electrode 1 is spot welded to the lower end portion of positive electrode terminal 5 fixed through glass insulation layer 4 to the cell cover 3. Then the positive electrode 1 and the positive electrode current collector 2 are surrounded by a separator 6 and a lithium board is pressure applied to the inner face of the cell cover 3 to form a negative electrode 7 which is fitted to the cell container 8 to laser weld the circumferential end section 3c of the cell cover and the flange section 8a of the cell container 8. Upon injection of electrolyte through an electrolyte injection port 9 made in the cell cover 3 by means of an injector, a nickel sealing plug 11 is inserted into said port 9 to incline the cell by 15 deg. against the horizontal face then a laser beam is irradiated from immediately above to weld the sealing plug 11 and the circumferential portion 3b of the injection port thus to seal the electrolyte injection port 9.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a thin sealed battery using an alkali metal as a negative electrode active material, an oxyhalide as a positive electrode active material and an electrolyte solvent.

[Conventional technology]

In a thin sealed battery with a completely sealed structure, the electrolyte is completely sealed, with alkali metals such as lithium and sodium used as the negative electrode active material, and oxyhalides such as thionyl chloride, phosphoryl chloride, and sulfuryl chloride used as the positive electrode active material and the electrolyte solvent. is injected into the battery through the electrolyte injection port provided on the battery lid, and after the electrolyte is injected, a sealing plug is inserted into the electrolyte injection port, and the sealing plug and the area around the electrolyte injection port on the battery lid are connected. The electrolyte injection port is sealed by laser welding or the like (unspecified literature).

[Problem that the invention seeks to solve]

However, as mentioned above, when the electrolyte injection port is sealed by welding after the electrolyte is injected, the electrolyte existing near the electrolyte injection port evaporates due to the heat generated during welding, and the internal pressure of the battery increases. This raises the problem of welding defects such as pinholes occurring in the weld, resulting in incomplete sealing, and the shape of the weld becoming distorted, resulting in a decrease in weld strength.

This is because in this type of battery, the oxyhalide such as thionyl chloride used in the electrolyte is also the positive electrode active material, so more electrolyte is injected than in other batteries.
On the other hand, in order to prevent the battery from rupturing due to thermal expansion of the electrolyte (destruction of the insulating layer made of glass, etc.), a void space of 10 to 30% by volume is provided inside the battery. The absorption speed is slow, and the electrolyte is not absorbed into the positive electrode immediately after injection, and the liquid level inside the battery is high, and as shown in FIG. It is thought that the existence is related.

[Means for solving problems]

This invention solves the above-mentioned problems of the prior art, and includes providing an electrolyte injection port on the periphery of the part of the battery cover that covers the opening of the battery container, and injecting the electrolyte into the battery from the electrolyte injection port. After injection and inserting the sealing plug into the electrolyte injection port, the electrolyte injection port is welded and sealed by tilting the battery so that there is no electrolyte near the electrolyte injection port. This prevents welding defects from occurring.

When implementing the present invention, injecting the electrolyte from the electrolyte injection port and inserting a sealing plug into the electrolyte injection port after injecting the electrolyte may be performed by tilting the battery, or by tilting the battery. You can go without it. In short, it is only necessary to seal the electrolyte injection port by welding in a state where the battery is tilted so that no electrolyte exists near the electrolyte injection port.

The tilt angle of the battery when welding and sealing the electrolyte inlet is:
10 to 20 degrees is preferable. This is because if the angle of inclination is less than 10 degrees, it is difficult to prevent the electrolyte from existing near the electrolyte inlet, whereas if the angle of inclination exceeds 20 degrees, the laser oscillator of laser welding, which is the preferred welding method, is difficult to prevent. but,
For safety reasons, the laser beam is usually placed directly above the workpiece, and the inclination angle is such that the laser beam irradiates the workpiece at right angles from directly above to below. This is because if the size becomes too large, the laser beam will not be properly irradiated onto the object to be welded, making it impossible to properly perform welding.

In addition, in this battery, the gas occupancy rate in the battery is 10~
The reason why it is set to 30% by volume is because the oxyhalide used as a solvent for the electrolyte also serves as the positive electrode active material, so we want to fill the battery with as much electrolyte as possible, and also to reduce the volume occupied by voids, that is, gas. If this is not left in place, it will not be possible to prevent the battery from rupturing when the electrolyte expands due to temperature rise due to use under high temperatures, etc., and the gas occupancy rate within the battery will be If the gas occupancy in the battery exceeds 30% by volume, it will not be safe enough to prevent the battery from bursting when the electrolyte expands thermally. This is because the discharge capacity decreases. In addition,
The gas in the above gas occupancy rate is usually air, but may also be an inert gas such as nitrogen or argon.

〔Example〕

Next, the present invention will be explained in more detail with reference to Examples.

FIG. 1 is a sectional view showing an example of a thin sealed/closed battery according to the present invention, and FIG. 2 is a plan view of the battery shown in FIG. 1.

However, FIG. 2 shows the state before the electrolyte injection port is welded and sealed. FIG. 3 is a sectional view showing a battery container used in the battery shown in FIG. 1.

Example 1 A positive electrode current collector 2 made of expanded nickel to which a positive electrode 1 made of a carbon porous molded body is crimped, and the lower end of a positive electrode terminal 5 attached to a battery lid 3 via an insulating layer 4 made of glass. After welding the parts at 7 spots, the positive electrode 1 and the positive electrode current collector 2 are wrapped with a separator 6 made of glass fiber nonwoven fabric,
A lithium plate is crimped onto the inner surface of the battery lid 3 to form the negative electrode 7, which is fitted into the battery container 8, and the peripheral end 3c of the battery lid 3 and the flange 8a of the battery container 8 are laser welded. did.

Next, pour the electrolyte 1 from the electrolyte inlet 9 provided on the battery lid 3.
After injecting 0 with a syringe, as shown in Fig. 4, insert a nickel sealing plug 11 into the electrolyte injection port 9, tilt the battery 15 degrees with respect to the horizontal plane, and irradiate the laser beam from directly above. The sealing plug 11 and the surrounding area 3 of the electrolyte inlet of the battery cover 3
b and welded to seal the electrolyte injection port 9.

In the above battery, the positive electrode l is made of acetylene black 100
A carbon porous molded body consisting of parts by weight, 10 parts by weight of phosphorous graphite, and 10 parts by weight of polytetrafluoroethylene,
It has a rectangular plate shape with dimensions of 25 mm x 30 mm and a thickness of 1.61 mm, and the lithium plate used to form the negative electrode 7 has a rectangular plate shape of 20 mm x 25 mm and a thickness of 0.81 mm. The electrolytic solution 10 is prepared by dissolving 1.2 mol/β of lithium aluminum tetrachloride in thionyl chloride, and thionyl chloride is not only the solvent of the electrolytic solution as described above, but also the positive electrode active material.

The amount of this electrolyte injected into the battery was 3.0 mi, and the gas occupancy rate of the battery after this electrolyte was injected (in this example, the gas was air, and the gas was filled with a special gas). Therefore, the porosity (usually called porosity) is 20
It is capacity %.

The battery container 8 is formed by drawing a stainless steel plate with a thickness of 0.51 mm, and has a flange 8a at the upper end as shown in FIG. 3, and the dimensions of the opening 8b of the battery container 8 are as follows. 4
[imm x 36mm. The battery cover 3 is made of a stainless steel plate with a thickness of 0.51, and the electrolyte inlet 9
As shown in FIG.
(10 mm inside from the inner peripheral edge of the upper end),
The diameter is 0.75mm. Note that 12 in FIG. 2 is an air vent hole for facilitating the injection of electrolyte, and like the electrolyte injection port 9, the battery container 8 of the part 3a of the battery cover 3 covers the opening 8b of the battery container 8. 10ffl from the inner edge of the upper end of
It is provided on the inside of I11, and its diameter is 0.75 mm. After injecting the electrolyte from the electrolyte injection port 9, the air vent hole 12 is sealed by inserting a sealing plug (not shown) in the same way as the electrolyte injection port 9, and by laser welding with the battery tilted. be done. However, this air vent hole 12 is not necessary when the electrolyte is injected by vacuum impregnation (the pressure inside the battery is reduced to replace the air inside the battery with the electrolyte).

The sealing plug 11 has an enlarged head 11a, the diameter of the shaft portion 11b is 0.70 mm, and the diameter of the head 11a is 1.0 mm.
The thickness of the head 11a is 0.2 mm. The laser welding conditions for sealing the electrolyte injection port are output 1.
The kW1 welding speed was 60 mm/sec.

Example 2 A battery was manufactured in the same manner as in Example 1, except that the electrolyte injection port was sealed by laser welding with the battery tilted 10 degrees with respect to the horizontal plane.

Example 3 A battery was manufactured in the same manner as in Example 1, except that the electrolyte injection port was sealed by laser welding with the battery tilted at 20 degrees with respect to the horizontal plane.

Comparative Example A battery was manufactured in the same manner as in Example 1, except that the electrolyte injection port was sealed by laser welding without tilting the battery.

Table 1 shows the incidence of welding defects when sealing the electrolyte inlet during the manufacture of the batteries of Examples 1 to 3 and the batteries of Comparative Example.

Table 1 As shown in Table 1, welding defects were drastically reduced by tilting the battery and sealing the electrolyte inlet by welding. In particular, when the battery was tilted at 15 degrees with respect to the horizontal plane, the rate of welding defects was lowest, and even if the angle was smaller or larger than this, there was a tendency for the occurrence of welding defects to increase. This is because when the tilt angle is smaller than 10 degrees, it becomes difficult to prevent the electrolyte from existing near the electrolyte injection port.On the other hand, when the tilt angle exceeds 20 degrees, the laser beam oscillator This is thought to be because the laser beam is installed so as to irradiate from directly above to directly below, which prevents proper welding. Nevertheless, as seen in Examples 2 and 3, by tilting the battery by 10 degrees and by tilting the battery by 20 degrees,
Compared to the comparative example in which there was no tilting at all, the occurrence of welding defects was greatly reduced.

〔Effect of the invention〕

As described above, in the present invention, the electrolyte injection port 9 is provided at the peripheral edge of the portion 3a of the battery lid 3 that covers the opening 8b of the battery container 8, and the electrolyte injection port 9 is welded and sealed after the electrolyte is injected. By tilting the battery so that the electrolytic solution 10 is not present in the vicinity of the electrolytic solution injection port 9, the occurrence of welding defects can be reduced when sealing the electrolytic solution injection port.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an example of a thin sealed battery according to the present invention, and FIG. 2 is a plan view of the battery shown in FIG. 1. However, FIG. 2 shows a state before the electrolyte injection port is welded and sealed, and FIG. 3 is a sectional view showing a battery container used in the battery shown in FIG. 1. FIG. 4 is a cross-sectional view schematically showing the main parts of a battery in the main steps when manufacturing a thin sealed battery by the method of the present invention, and FIG. FIG. 3 is a cross-sectional view schematically showing the main parts of the battery in the main steps. 1... Positive electrode, 3... Battery lid, 3a... Portion of the battery lid that covers the opening of the battery container, 3b... Portion around the electrolyte inlet of the battery lid, 6... Separator, 7
... Negative electrode, 8... Battery container, 8b... Opening of battery container, 9... Electrolyte inlet, 10... Electrolyte, 11... Sealing plug Patent applicant Hitachi Maxell Co., Ltd. Figure 3 Figure 4

Claims (2)

[Claims] (1) An electrolytic solution in which an alkali metal is used as a negative electrode active material, an oxyhalide is used as a positive electrode active material and an electrolyte solvent, the gas occupancy in the battery is 10 to 30% by volume, and the electrolyte 10 is provided in the battery lid 3. The electrolyte is injected into the battery through the injection port 9, and after the electrolyte is injected, the sealing plug 11 is inserted into the electrolyte injection port 9.
1 and the peripheral portion 3b of the electrolyte inlet of the battery lid 3 to seal the electrolyte inlet 9. In manufacturing a thin sealed battery, the electrolyte inlet 9 is connected to the opening of the battery container of the battery lid 3. After injecting the electrolyte 10 into the battery from the electrolyte injection port 9, the sealing plug 11 and the peripheral portion 3b of the electrolyte injection port 9 of the battery cover 3 are connected to the battery. Tilt it so that there is no electrolyte 10 near the electrolyte injection port 9,
A method for manufacturing a thin sealed battery, characterized in that the electrolyte injection port 9 is sealed by welding. (2) The method for manufacturing a thin sealed battery according to claim 1, wherein the inclination angle of the battery when the electrolyte inlet 9 is welded and sealed is 10 to 20 degrees.