JPH0265052A - Flat sealed battery - Google Patents

Abstract

PURPOSE:To obtain the high sealability of a flat sealed battery and prevent the battery bursting under the high pressure by using a metallic ball as sealing body of the flat sealed battery and providing a cross shaped thin part for the explosion proof in the sealing plate. CONSTITUTION:A cylindrical or taper tubelous electrolyte filler hole 12 having its tip at the inner side of a battery is provided at the center of a bottom part 5a of a battery vessel 5, and after the filling of the electrolyte, a sealing plug 13 made of a metallic ball is pressed-in the electrolyte filler hole 12. And the opening of the base end side of the electrolyte filler hole 12 is covered by a metallic sealing plate 14 in which a thin part 15 for the explosion proof is provided, and the outer peripheral part of the sealing plate 14 is welded to the bottom part 5a of the battery vessel 5. Thereby, at the time of welding of the sealing plate 14, the vaporized material of the electrolyte can not come fly to the part to be welded so that the outer peripheral part of the sealing plate 14 can be welded to the bottom part 5a of the battery vessel 5 without any hindrance. And the thin part 15 provided in the sealing plate 14 is destroyed by the pressure within the range that the safety can be secured and the battery bursting under the high pressure can be prevented.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a flat sealed battery with an explosion-proof function.

[Conventional technology]

In recent years, with the development of electronic devices, lithium batteries with low self-discharge and long life have come into widespread use.

Therefore, as a memory backup power source for CMOS RAM, a cylindrical metal-glass-metal hermetic seal was adopted for the battery lid, and a thium-thionyl chloride battery was developed (for example, Japanese Patent Laid-Open No. 59-51458).
Demand for these products is rapidly increasing because they have a high airtightness and can be used for more than 10 years.

However, in addition to the above-mentioned cylindrical pack-tub batteries, the market is demanding smaller and thinner memory backup batteries due to the need to reduce the current consumption of ICs, or to reduce the size and weight of devices. ing.

Therefore, attempts have been made to develop flat batteries in order to meet such demands, but in the case of flat batteries, an electrolyte inlet is provided at the terminal part of the battery lid, as is used for cylindrical batteries. This cannot be used because the heat generated during welding and sealing would damage the glass layer.

In other words, in the case of a cylindrical battery, the shape is large and the total height of the battery is at least 25 cm, so even if the electrolyte inlet is provided in the terminal part located in the center of the battery lid, the sealing position of the electrolyte inlet can be set at a distance in the height direction from the glass layer of the battery lid, so the glass layer will not be damaged by the heat during welding and sealing.
For flat batteries with a total battery height of at most 10m+m, when an electrolyte inlet is provided at the terminal part of the battery lid, the distance between the welded sealing part and the glass layer is short, so the heat generated during welding and sealing is This causes the glass layer to break and become unusable.

Furthermore, even if an electrolyte inlet is provided in another part, the distance between the welded sealing part and the electrolyte must be close, so the electrolyte may vaporize due to the heat during welding and sealing. Since the particles fly into the welded parts, problems such as pinholes forming in the welded parts and reduced airtightness occur, and despite the market demand for flat sealed batteries, they have not been commercialized. The reality was that there was no such thing.

Therefore, the inventors of the present invention have made repeated studies in order to meet such demands, and have provided a cylindrical or tapered cylindrical electrolyte inlet in the center of the bottom of the battery container with a tip on the inside of the battery. After injecting the electrolyte, press fit a sealing plug into the electrolyte injection port to temporarily seal the electrolyte injection port, and then close the opening on the base end side of the electrolyte injection port with a metal sealing plate. by covering and welding the outer periphery of the sealing plate to the bottom of the battery container,
We have developed a flat sealed battery with a hermetic seal that uses liquid oxyhalide as a soil scraping material and has a highly hermetic seal.

[Problem to be solved by the invention]

However, although batteries employing the above-mentioned hermetic seal have the advantage of being highly airtight and have excellent storage properties, on the other hand, due to their high airtightness,
When a battery encounters an abnormal situation such as being exposed to high temperature heating or being charged at a high voltage, the internal pressure of the battery rises abnormally and the battery ruptures under high pressure, resulting in a so-called battery explosion. A loud bursting sound is generated, and the contents of the battery are scattered around, contaminating equipment that uses the battery.

[Means to solve the problem]

The present invention uses a metal ball as a sealing stopper in the flat sealed battery, provides a thin section for explosion protection on the sealing plate in a cross shape, uses an oxyhalide as a royal active material, and employs a hermetic seal. The present invention provides a highly safe flat sealed battery that has high sealing properties and can prevent battery explosion under high pressure.

That is, the structure of the present invention will be explained based on FIGS. 1 to 6 corresponding to the embodiments. Alternatively, a tapered cylindrical electrolyte injection port 0'' is provided, and after injecting the electrolyte, a sealing plug surface made of a metal ball is press-fitted into the electrolyte injection port (121), and the proximal end of the electrolyte injection port 0''IJ is The side opening is covered with a metal sealing plate (14) having a cross-shaped thin part 05) for explosion-proofing, and the outer periphery of the sealing plate 05 is welded to the bottom (5a) of the battery container 00. This invention relates to a flat sealed battery characterized by:

[Effect]

First, when welding the sealing plate 04), the sealing plug 0■ is press-fitted into the cylindrical or tapered cylindrical electrolyte inlet 0, so the electrolyte inlet is inserted into the sealing plug side from around it. (12
1 is applied, the closeness between the two increases, and at least until the welding of the sealing plate 04) is completed, the sealing plug 0'! Since the electrolyte inlet (+21) is sealed by J, vaporized electrolyte does not fly to the welding part when welding the sealing plate (14), and therefore the outer periphery of the sealing plate (14) the bottom (5a) of the battery container (5)
Welding can be performed without any hindrance, and pinholes do not occur.

If the battery encounters an abnormal situation, such as being exposed to high temperature heating or being charged at a high voltage, and the pressure inside the battery rises abnormally, the electrolyte injection port ( The sealing stopper 0■ made of a metal ball that had been press-fitted into the sealing plate 04 is pushed back, contacts the sealing plate 0, and presses the sealing plate 04, so that the thin wall portion 05 provided on the sealing plate 04
) is destroyed at a pressure within a safe range, preventing the battery from bursting under high pressure, or in other words, from exploding the battery.

C Embodiment] Next, an embodiment of the present invention will be described based on the drawings. However, although a lithium-thionyl chloride flat sealed battery will be described in the Examples, the present invention is not limited to that case.

FIG. 1 is a sectional view showing an embodiment of the flat sealed battery of the present invention, and FIG. 2 is a schematic bottom view of the battery shown in FIG. 1. However, in the cross-sectional view of the battery, outline lines of portions located on the back side of the cross section, which may make the drawings complicated if shown, are omitted. Figure 3 shows an enlarged view of the sealing plate used in the battery shown in Figure 1. Figure 3 (a) is its top view, and Figure 3 (b) is the same as that of Figure 3 (a). A-A line sectional view, Figure 3 (C)
3(a) is a sectional view taken along line BB in FIG. 3(a), and FIG. 3(d) is a bottom view.

First, to roughly explain the structure of the battery, (+1
is a negative electrode made of lithium, (2) is a positive electrode made of a porous carbon molded body, and (3) is a separator made of glass fiber nonwoven fabric, which separates the negative electrode (1) and the positive electrode (2).
t, tiru. (4) is an electrolyte, (5) is a stainless steel battery container, and (6) is a battery lid.
) is an annular stainless steel body (7), an insulating layer (8) made of glass, and a stainless steel positive terminal (9).
), and the outer periphery of the body (7) is a battery container (
It is welded to the open end of 5). Oω is the current collector on the positive electrode side, which is made of stainless steel mesh, and the terminal on the positive electrode side (
9) is spot welded at the bottom. 0() is an insulator made of glass fiber nonwoven fabric, which insulates between the positive electrode (2) and the positive electrode current collector 0ω and the body (7) of the battery lid (6). (12) is an electrolyte injection port, and this electrolyte injection port (12) is provided at the center of the bottom (5a) of the battery container (5), but in this example, the tip is connected to the battery. It is formed into a cylindrical shape that exists on the inside, and a sealing plug 0 made of a stainless steel ball is press-fitted after the electrolyte is injected.

041 is a sealing plate made of stainless steel, the central part of which covers the opening on the base end side of the electrolyte inlet (121), and the outer peripheral part is welded to the bottom (5a) of the battery container (5). .

Further, on this sealing plate side, as will be described in detail later, two thin-walled parts for explosion-proofing are provided in a cross shape. This battery is a disk-shaped flat battery with an outer diameter of 33mm and a total height of 6.5+111mm.

Next, we will explain the main components in detail.
Negative 1) is a lithium sheet punched into a ring shape and crimped onto the bottom inner surface of the battery container (5), and is composed only of lithium as the negative electrode active material, while the positive electrode (2) is mainly composed of acetylene black. , a porous molded body made of a material mainly composed of carbonaceous material to which graphite and polytetrafluoroethylene are added, a so-called carbon porous molded body.

Electrolyte solution (4) is 1 lithium aluminum tetrachloride in thionyl chloride, Omol/j! It consists of a dissolved thionyl chloride solution, and thionyl chloride is both the electrolyte solvent and the positive electrode active material as described above. As can be seen from the fact that thionyl chloride is used as the positive electrode active material, the positive electrode (2) itself does not react, but is ionized from the positive electrode active material thionyl chloride and the negative electrode (1). This provides a site for reaction with lithium ions that have been eluted.

The battery container (5) is made of a stainless steel plate with a thickness of 0.5ffim and is formed into a container shape with a diameter of 331 cm and a height of 6ffi11,
The central part of the bottom (5a) is made to protrude toward the inside of the battery (from the outside of the bottom of the battery, it is recessed towards the inside of the battery), and the center of the protruding part has an inner diameter of 2.11I.
At I11, a cylindrical electrolyte injection port (+21) with a height of about 1.51 with a tip on the inside of the battery is provided. This means that the gap through which the electrolytic solution can pass is formed by a cylinder.

As mentioned above, the battery cover (6) has a stainless steel body (
7), an annular insulating layer (8) made of glass, and a positive terminal (9) made of stainless steel. ), and the inner circumferential surface is welded to the outer circumferential surface of the stainless steel positive terminal (9), and has a so-called metal-glass-metal hermetic seal. As such, the body (7) of the battery cover (6) is welded to the open end of the battery container (5), and this battery is configured to have a so-called completely sealed structure.

The sealing plug 0■ consists of a stainless steel ball with a diameter of 2.3n+n+, and the diameter of this sealing plug side is the same as that of the electrolyte injection port (121
It is slightly larger than the inner diameter of the electrolyte injection port (
12). Therefore, the repulsive stress of the electrolyte inlet (12) is applied to this sealing plug surface from the surrounding area, and the closeness between the two increases, so that the electrolyte inlet Q2) is at least sealed by the sealing plate (b). Until the stop welding is completed,
It is sealed with the above-mentioned sealing plug. Therefore, at least the outer periphery of the sealing plate (b) is connected to the bottom (5) of the battery container (5).
Until the welding is completed in 5a), the vaporized substance of the electrolyte does not come out to the welding part, so welding can be performed smoothly without being hindered, and pinholes do not occur. The sealing plate θa has a thickness of 0.3 mm and a diameter of 5
+*m stainless steel plate, its central part covers the proximal opening of the electrolyte inlet 07J, and its outer periphery is welded to the bottom (5a) of the battery container (5) using a carbon dioxide laser. (Welding conditions are Dekani 400W, welding speed:
20mm/5ec), thereby the electrolyte injection port θ'! J is completely sealed.

As shown in detail in FIG. 3, the sealing plate OIO is provided with a cross-shaped thin part 0ω for explosion protection. This thin-walled portion 05) is formed by, for example, press working into a cross-sectional shape as shown in FIG. is provided by forming a trapezoidal (but convex) groove 00, and here, the thin wall portion 05
) has a thickness t of 0.07 m5, and a width W of the thin portion c of 0.07 m5.
15 mm, and the forming angle θ of the groove 0ω is 60′.

The battery of this example is constructed as described above, so if
If this battery encounters an abnormal situation, such as being exposed to high temperature heating or being charged at a high voltage, and the pressure inside the battery begins to rise abnormally, the pressure increase may cause the electrolyte inlet to close. The sealing plug 03) that has been press-fitted is pushed back, comes into contact with the sealing plug α4, and presses the sealing plate (b). As a result, the thin wall part 051 on the sealing plate side breaks under pressure within the range that can ensure safety before the pressure becomes high (the end of the thin wall part 051 ruptures), and the battery ruptures under high pressure. In other words, explosions are prevented.

FIG. 5 is a sectional view showing another embodiment of the flat sealed battery of the present invention, and FIG. 6 is a schematic bottom view of the battery shown in FIG. 5.

In the battery shown in FIG. 5, the electrolyte injection port (12+) has a tapered cylindrical shape, and the diameter of the sealing plate (B) has increased to 6--, etc. It is different from the battery shown in Figure 1, except for the battery shown in Figure 1 above.
The structure is almost the same as the battery shown in the figure. Note that the electrolyte injection port (121) having a tapered cylindrical shape means that the tapered tube forms a gap through which the electrolyte can pass when the electrolyte is injected.

In the battery shown in FIG. 5 as well, the electrolyte inlet (12) is provided at the center of the bottom (5a) of the battery container (5) (however, the electrolyte inlet (12) is provided at the center of the bottom (5a) of the battery container (5). The electrolyte inlet (+2) has a tapered shape, and the electrolyte inlet (+2) is tapered. The inner diameter of the tip of (12) with the smallest inner diameter is 2.1 mm, and the diameter of the stainless steel ball of the sealing plug Q3) is 2.3 ff.
lIm, and the diameter of the sealing plug 031 is the electrolyte injection port 0.
The electrolyte injection port (sealing plug 03 in 121) is press-fitted into the electrolyte injection port (121). The opening on the base end side of the electrolyte inlet 0 is an explosion-proof thin wall part 0! IO
The sealing plate (1) is covered with a sealing plate (04) provided in a cross shape.
The outer periphery of 4) is welded to the bottom (5a) of the battery container (5) (the protruding central portion) using a carbon dioxide laser. The above sealing plate 04) has a diameter of 6 mm,
It is made of a stainless steel plate with a thickness of 0.31111 mm, and the thickness of the cross-shaped thin wall portion 05) is 0.07+ue as in the case of the battery shown in FIG. 1.

Therefore, this battery is also exposed to high temperature heating,
If the battery encounters an abnormal situation, such as being charged at a high voltage,
When the internal pressure of the battery begins to rise abnormally, the sealing plug 03 press-fitted into the electrolyte injection port QZ is pushed back due to the internal pressure rise, and comes into contact with the sealing plate 04), causing the sealing plate 0 to close.
4), the q thin-walled portions of the sealing plate 041 are destroyed under pressure within a safe range, thereby preventing the battery from bursting under high pressure, that is, from exploding.

Next, high-temperature heating tests were conducted on the battery of the example shown in Figure 1 above and the battery of the example shown in Figure 5, and Table 1 shows the results of the operation status of the explosion-proof function due to the destruction of the thin wall part 0ω. In Table 1, the battery according to the example shown in Figure 1 is designated as battery A, and the battery according to the example shown in Figure 5 is designated as battery B. In the high temperature heating test, 10 pieces of each of both batteries were prepared. Then, put the battery in an electric Matsufuru furnace, and increase the heating rate to 3.
It was heated at 0°C/min and the operating status of the explosion-proof function at that time was investigated. In addition, the denominator of the numerical value in the column representing "operation status of explosion-proof function" in Table 1 indicates the number of batteries subjected to the test, and the numerator indicates the number of batteries in which the thin wall part 05) was destroyed and the explosion-proof function was activated. ing.

Table 1 As shown in Table 1 above, the batteries of the present invention, for both Battery A and Battery B, operate in the temperature range of 170-230'C, and are not exposed to high-temperature heating. In such a case, the explosion-proof function due to the destruction of the thin wall portion 051 was activated before the battery temperature became too high, that is, before the pressure inside the battery became too high. By the way, a battery with a similar structure but without an explosion-proof thin section on the sealing pressure plate was tested at a temperature of 250 to 290°C in the high-temperature heating test mentioned above.
The bottom of the battery container broke in the temperature range of 200 to 3000, causing a so-called battery explosion.

Next, instead of mounting the battery as in the case of the high-temperature heating test, a power generating element such as a page-turning element was placed in the battery container (5) of the battery shown in FIG. 1 and the battery container (5) of the battery shown in FIG. The same sealing plugs 03) as described above are press-fitted into the electrolyte injection ports (12) of these battery containers (5) without filling them at all, and the opening on the proximal end side of the electrolyte injection ports Q21 is press-fitted. is covered with a sealing plate 04 having a cross-shaped thin wall portion 0ω for explosion protection, and the outer periphery of the sealing plate is welded to the bottom (5a) of the battery container (5) using a carbon dioxide laser, and the electrolyte is injected. The inlet (12) is sealed, these battery containers (5) are connected to a pressurizing jig, pressurized with water pressure, and the burst pressure of the thin-walled parts θ for explosion protection is checked.
The results are shown in Table 2.

In the test, 10 battery containers (5) for battery A and 10 battery containers (5) for battery B were used.

Table 2 As shown in Table 2 above, battery A0) battery container (5),
The battery container (5) of battery B also has a thin wall part 0 on its sealing plate side.
5) was destroyed at 80 to 110 kg/cd, but for comparison, welded a sealing plate 041 without any thin-walled parts for explosion protection to the battery container of each battery (Battery A and Battery B). When a similar pressure test was conducted with
At 0 kg/d, the battery container broke, accompanied by a loud bursting sound.

As is clear from the results of the high-temperature heating test and pressurization test, the batteries of the examples of the present invention do not encounter abnormal situations such as being exposed to high-temperature heating or being charged at high voltage. When the internal pressure of the battery begins to rise abnormally, the explosion-proof thin wall part 0ω provided on the sealing plate 04 will break under pressure within a safe range, causing the battery to burst under high pressure, i.e. Explosion can be prevented.

In the above embodiment, the sealing stopper is made of stainless steel, but it may be made of nickel or the like instead of stainless steel.

In addition, in the embodiment, in order to prevent the sealing plate from protruding from the bottom of the battery container (5) to the outside of the battery, the center portion of the bottom (5a) of the battery container (5) is made to protrude toward the inside of the battery. The electrolyte inlet (12) was provided in the protruding part, but the electrolyte inlet (121) was provided without protruding the center part of the bottom (5a) of the battery container (5). Good too.

Further, in the embodiment, the insulating layer (8) is made of glass, but the insulating layer (8) may be made of ceramic instead of glass. In the example, a lithium-thionyl chloride battery was described in which lithium was used as the negative electrode active material and thionyl chloride was used as the positive electrode active material. However, the negative electrode active material may be an alkali metal other than lithium such as sodium or potassium. Alternatively, the positive electrode active material may also be an oxyhalide that is liquid at room temperature (25° C.), such as sulfuryl chloride or phosphoryl chloride, in addition to thionyl chloride.

In addition, in the present invention, the shape of the electrolyte inlet is described as being cylindrical or tapered, but since the present invention is intended for flat batteries with a total battery height of about 10+ on, the shape of the electrolyte injection port is not limited to those heights. As shown in the example, ], 5
It is about mm in height and is not very tall.

In addition, the part of the sealing plate 0a to be welded to the bottom (5a) of the battery container (5) was expressed as its outer periphery, but the part to be welded is the opening on the base end side of the electrolyte injection port 0. It only needs to be around the periphery, and this expression corresponds to the expression that the part covering the opening on the proximal end side of the electrolyte inlet (12+) is the central part, and the sealing plate Q41 has a large diameter. , it does not refer only to a part near the outer peripheral edge.

〔Effect of the invention〕

As explained above, in the present invention, a cylindrical or tapered cylindrical electrolyte inlet q is provided in the center of the bottom (5a) of the battery container (5), and after the electrolyte is injected, the electrolyte inlet 0
A sealing plug θ made of a metal ball is press-fitted into the hole, and the opening on the proximal end side of the electrolyte inlet 0'IJ is connected to the explosion-proof thin wall G.
The sealing plate (14) is covered with a sealing plate 04 provided in a cross shape.
) is welded to the bottom (5a) of the battery container (5) and the electrolyte inlet (12) is sealed, thereby using an oxyhalide as the positive electrode active material and adopting a hermetic seal. It was possible to provide a highly safe flat sealed battery that can prevent battery rupture under high pressure, that is, battery explosion, while maintaining high sealing performance.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the flat sealed battery of the present invention, and FIG. 2 is a schematic bottom view of the battery shown in FIG. 1. Figure 3 shows an enlarged view of the sealing plate.
) is the plan view, and Fig. 3 (c) is the A-A of Fig. 3 (a).
Line sectional view, Figure 3 (C) is Figure 3 (a) (7) B-B
A line sectional view, and FIG. 3(d) is a bottom view. FIG. 4 is an enlarged sectional view of the thin wall portion provided on the sealing plate and its surroundings. Fifth
The figure is a sectional view showing another embodiment of the flat sealed battery of the present invention, and FIG. 6 is a schematic bottom view of the battery shown in FIG. 5. (1)...Negative pole, (2)...Kingship, (3)...
・Separator, (4)... Electrolyte, (5)... Battery container, (5a)... Bottom, (6)... Battery lid,
(7)...Body, (8)...Insulating layer, (9)
...terminal, (12)...electrolyte inlet, q■・
...Sealing plug, 04...Sealing plate, 09...Thin wall part Fig. 14...Sealing plate 15...Thin wall part Fig.

Claims (1)

[Claims] (1) An alkali metal such as lithium, sodium, or potassium is used as the negative electrode active material, and an oxyhalide that is liquid at room temperature such as thionyl chloride, sulfuryl chloride, or phosphoryl chloride is used as the positive electrode active material. A flat sealed battery in which a power generation element containing a substance is sealed between a battery container (5) and a battery lid (6), wherein the battery lid (6) is made of metal and includes a metal annular body (7) and the annular body. (7) An annular insulating layer (8) made of glass or ceramics located on the inner circumference side and the annular insulating layer (8)
The outer periphery of the body (7) of the battery lid (6) is welded to the open end of the battery container (5). A cylindrical or tapered cylindrical electrolyte injection port (12) having a tip on the inside of the battery is provided in the center of the bottom (5a) of 5), and after the electrolyte injection, the electrolyte injection port (12) A sealing plug (13) made of a metal ball is press-fitted into the electrolyte injection port (12).
) is covered with a metal sealing plate (14) having a cross-shaped explosion-proof thin walled part (15), and the sealing plate (
14) A flat sealed battery characterized in that the outer periphery of the battery container (5) is welded to the bottom (5a) of the battery container (5).