JPH0265054A - Flat sealed battery - Google Patents

Abstract

PURPOSE:To obtain a flat sealed battery comprising an explosion proof function having the high sealability and the high safety by providing a ring thin part at the bottom part of a battery vessel so that the ring thin part has a diameter within the specific range to the outer diameter of the battery vessel. CONSTITUTION:In a battery using a harmetic seal, a ring thin part 15 for the explosion proof is provided at the bottom part 5a of a battery vessel 5 so that the thin part has a diameter of 19-87% to the outer diameter of the bottom part 5a of the battery vessel 5. Thereby, when the internal pressure starts to rise abnormally, the thin part is destroyed by the pressure within the range that the safety can be secured and the battery bursting under the high pressure, that is, the explosion can be prevented so as to improve the safety and also obtain the high sealability.

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 R'AM, a cylindrical lithium-thionyl chloride battery with a metal-glass-metal hermetic seal on the battery lid was developed (e.g., Japanese Patent Laid-Open No. 59-51458). Demand for these products is rapidly increasing because they have a high sealing performance and can be used for more than 10 years.

However, in the market, there are not only cylindrical bank-up batteries as mentioned above, but also 1.
Furthermore, due to the demand for smaller and lighter equipment, smaller and thinner batteries for memory bank amplifiers are required.

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 + s-, so even if the electrolyte inlet is provided in the terminal part located in the center of the battery lid, the electrolyte inlet cannot be sealed. Since the stop position can be set at a distance in the height direction from the glass layer of the battery cover, the glass layer will not be damaged by the heat during welding and sealing, but the total height of the battery will increase. For flat batteries of about 10mm+, when an electrolyte inlet is provided at the terminal part of the battery lid, the glass layer may be destroyed by the heat during welding and sealing because the distance between the welded sealing part and the glass layer is short. This makes it unusable.

For this reason, despite the market demand for flat sealed batteries that use oxyhalides as positive electrode active materials and employ hermetic seals, they have not been commercialized.

Therefore, the inventors of the present invention have conducted repeated studies in response to such requests, and have created a hermetic seal by using a liquid oxyhalide as a positive electrode active material by providing an electrolyte injection port in the center of the bottom of the battery container. We have developed a flat sealed battery with high airtightness.

[Problems to be Solved by the Invention] However, although batteries employing the above-mentioned hermetic seal have the advantages of high sealing performance and excellent storage performance, on the other hand, due to the high sealability,
When a battery encounters an abnormal situation such as being exposed to high temperature heating or being charged at high voltage, the internal pressure of the battery increases abnormally and the battery ruptures under high pressure, resulting in a so-called battery explosion. A popping sound is generated, and the contents of the battery are scattered around, contaminating the equipment using the battery.

Therefore, in cylindrical batteries, a thin-walled section is provided in the shape of a cross at the center of the bottom of the battery container to ensure safety that the thin-walled section does not become too high pressure when the internal pressure of the battery begins to rise abnormally. This is done to prevent the battery from bursting under high pressure, or so-called explosion, by applying as much pressure as possible, but flat batteries have an electrolyte inlet in the center of the bottom of the battery container, as mentioned above. There is a situation in which a thin walled part for explosion protection cannot be provided at the center of the bottom of the battery container due to the provision of the battery case.

[Means to solve the problem]

The present invention provides an annular thin-walled portion at the bottom of the battery container so that the diameter of the annular thin-walled portion is in the range of 19 to 87% of the outer diameter of the battery container, thereby dissolving the oxyhalide into the positive electrode active material. The present invention provides a flat sealed battery that uses a hermetic seal to provide high airtightness and is highly safe and explosion-proof.

[Example] Next, an example 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 views, outline lines of portions located on the back side of the cross-section, which may make the drawings complicated if shown, are omitted.

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 carbon porous molded body, and (3) is a separator made of glass fiber nonwoven fabric, which separates the negative electrode (1) and the positive electrode (2). (4) is an electrolytic solution, (5) is a battery container made of stainless steel, and (6) is a battery lid. This battery lid (6) is annular and is made of a stainless steel body (7) and glass. insulation layer (8) and stainless steel positive terminal (9)
), and the outer periphery of the body (7) is a battery container (
5) At the open end? 6 is connected. 00) is the current collector on the positive electrode side, which is made of stainless steel mesh and has a spot at the bottom of the terminal (9) on the positive electrode side. 8 is connected. θ1) 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). 07J is an electrolyte injection port, and this electrolyte injection port 021 is provided at the center of the bottom (5a) of the battery container (5), but in this example, the tip is located inside the battery. It is formed into a cylindrical shape, and a sealing plug 0ω made of a polytetrafluoroethylene ball is press-fitted after the electrolyte is injected. The side is a stainless steel sealing plate that covers the opening on the proximal side of the electrolyte inlet in the center.
The outer periphery is welded to the bottom (5a) of the battery container (5). This battery has an outer diameter of 33 mm and a total height of 6.
It is a flat battery with a disc shape of 5mm+.

Next, we will explain the main components in detail.
The negative electrode (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, which is the active material for page turning, and the positive electrode (2) is composed mainly of acetylene black. It consists of a porous molded body made of a material whose main material is carbonaceous material, to which fi[% lead and polytetrafluoroethylene are added, so-called carbon porous molded body. The electrolytic solution (4) consists of a thionyl chloride solution in which 1.0 mol/l of lithium aluminum tetrachloride is dissolved in thionyl chloride, and thionyl chloride is not only the electrolytic solution solvent but also the positive electrode active material as described above. As is clear from the fact that thionyl chloride is used as the positive electrode active material, the positive electrode (2) itself does not react, but rather reacts with the positive electrode active material thionyl chloride and the negative electrode (1). This provides a site for reaction with ionized and eluted lithium ions.

The battery container (5) is made of a stainless steel plate with a thickness of 0 mm and 5111 m, and is shaped like a container with an outer diameter of 33 mm and a height of 6 I. The center of the bottom (5a) has an inner diameter of 2.1 mm and a tip on the inside of the battery. A cylindrical electrolyte inlet having a height of approximately 1.5 mm is provided. Note that the cylindrical electrolyte injection port 02) means that a cylinder forms a gap through which the electrolyte can pass during injection of the electrolyte.

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 positive terminal (9) made of stainless steel, and has a so-called metal-glass-metal hermetic seal. As shown in the figure, 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.

In this example, the sealing plug 03) is made of a polytetrafluoroethylene bulb with a diameter of 2.3 ma+, and the diameter on the side of this sealing plug is slightly larger than the inner diameter of the electrolyte injection port θ, and after the electrolyte is injected. It is press-fitted into the electrolyte inlet θ. Therefore, the electrolyte inlet 02 is connected to this sealing plug q■ from its surroundings.
1 is applied, the closeness between the two becomes high, and the electrolyte inlet Oz is sealed by the sealing plug 0''5 at least until welding of the sealing plate 04 is completed. So to speak, the electrolyte inlet Q is temporarily sealed by this sealing plug (+3), and the battery container (5) on the outer periphery of the sealing plate 010 is closed.
) is completely sealed by welding to the bottom (5a).

The sealing plate 04 is made of a stainless steel plate with a thickness of 0.3 mm and a rolled diameter of 0.45 mm, and its central part covers the proximal opening of the electrolyte inlet 021, and its outer periphery covers the battery container (5 mm). )
Welding is performed on the bottom part (5a) using a carbon dioxide laser at an output of 400 W and a welding speed of 20 III/sec.

The bottom (5a) of the battery container (5) is provided with an annular explosion-proof thin wall (15).
The thickness of the battery case (5) is 0.07 m-, and the diameter of the thin wall part (15) (this is the diameter between the centers of the thin wall parts, see reference numeral B in Figure 2) is the same as that of the battery container (5). Bottom (5a)
It is made to be 19% to 87% of the outer diameter of.

The fact that the diameter of the thin wall portion 0ω is 19 to 87% of the outer diameter of the bottom (5a) of the battery container (5) as described above was determined from the following experiment.

First, as shown in FIG. 3, a battery container (5) is prepared in which an electrolyte inlet 021 is provided in the center of the bottom (5a) and a thin wall portion 0ω is provided in an annular shape. In addition, in the experiment, the outer diameter A (see Fig. 2) of the bottom part (5a) of the battery container (5) was kept constant at 3:3gn+, and the diameter B (
(see Figure 2), the value of B/A is 0 (this indicates that no thin part is provided), 0.09.0
．． 19.0.31.0.47.0.62.0.78.0
．． 87 and 0.93, various types of battery containers (5) are prepared.

The thin wall portion 05) is provided by forming a groove 06) having a trapezoidal (but convex) cross section in the bottom portion (5a) of the battery container (5), for example, by press working, as shown in FIG. Here, the thickness t of the thin portion 0ω is 0.07 mm, and the width W of the thin portion surface is 0.15 mm.

The forming angle θ of the groove 0ω is set to 60°.

Then, without putting any electrolyte or the like inside these battery containers (5), the opening on the base end side of the electrolyte injection port 0z is covered with a sealing plate round, and the sealing plate 04) The outer periphery of the battery container (5) is sealed by welding to the bottom (5a) of the battery container (5) using a carbon dioxide laser.

The battery container with the electrolyte injection port 0 sealed in this way (
5) is attached to a pressurizing jig and pressurizes the battery container (5) with water pressure to destroy the thin wall part 09 (the end of the thin wall part surface ruptures).
The pressure generated was investigated and the results are shown in Table 1.

However, when the value of B/A is O, the bottom (5a) of the battery container (5) will burst because the thin wall portion 0ω is not provided.

The problem is how much pressure should be set to prevent the explosion-proof function from rupturing when the thin-walled part 05) in Table 1 is destroyed, and the explosion-proof function is activated, but as shown in Table 1, the thin-walled part 00 is Since the pressure at which the bottom of the battery container bursts when it is not installed (that is, when B/A=e) is 400 kg/cJ, the upper limit for the activation pressure of the explosion-proof function should be set at about 180 kg/cd. is considered preferable. In addition, under normal usage conditions, the internal pressure of the battery rarely rises above 10 kg/cd, taking into account the drop in burst pressure due to slight variations and corrosion of the thin wall part 05) during long-term storage. However, if the explosion-proof function is set to operate at a pressure of 30 kg/c4 or more, it is unlikely that the explosion-proof function will operate even when there is no abnormal situation.

From this perspective, the value of B/A is 0.19 to 0.93.
That is, it can be said that it is preferable to set the diameter of the thin wall portion 05) to 19 to 93% of the outer diameter of the bottom portion (5a) of the battery container (5).

Next, with the structure shown in Figure 1, the B/A value is 0.0.09.
．． 0.19.0.31.0.62.0.78.0.87
and 0.93, and a high temperature heating test was conducted to examine the operation status of the explosion-proof function due to destruction of the thin-walled portion 09. For the high temperature heating test, 10 batteries of each B/A value were prepared, and the batteries were placed in an electric Matsufuru furnace.
Heating was performed at a heating rate of 30°C/min, and the operating status of the explosion-proof function at that time was investigated, and the results are shown in Table 2. In addition, the denominator of the numerical value representing "operation status of explosion-proof function" in Table 2 indicates the number of batteries subjected to the test, and the numerator indicates the number of batteries in which the thin wall part (15) was destroyed and the explosion-proof function was activated. There is.

Table 2 As shown in Table 2, when B /A = 0.09,
The explosion-proof function of seven of the ten batteries was activated, but the explosion-proof function of the remaining three batteries was not activated, and the bottom of the battery container burst. When B/A becomes 0.19 or more, the explosion-proof function of all the batteries tested becomes activated, and their operating temperature is B/A=O, 19 to 0.8.
7 is 160-230'C, but B/A=0.9
3, there was one that operated at 140°C.

Considering that the battery temperature may reach about 120° C. under normal operating temperature, it is considered that the explosion-proof function of a battery with B/A=0.93 may operate during normal use without abnormal conditions. Therefore, B/A=0.19-0.
87, that is, if the diameter of the explosion-proof thin-walled part (15) is 19 to 87% of the outer diameter of the bottom (5a) of the battery container (5), the thin-walled part can be sealed at a pressure within the range that ensures safety. 0ω
It can be said that the explosion-proof function is activated when the explosion-proof function is activated, preventing the battery from bursting under high pressure, or so-called explosion, and the explosion-proof function is not activated and the battery function is not lost in normal situations.

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.

The battery shown in FIG. 5 is almost the same as the battery shown in FIG. 1 above, except that the electrolyte injection port 02) is made into a tapered cylindrical shape, and the diameter of the sealing plate θ4 is slightly increased to 51. It is configured. Note that the electrolyte injection port θ has a tapered cylindrical shape, which means that the tapered cylinder forms a gap through which the electrolyte can pass during injection of the electrolyte.

In other words, even in the battery shown in FIG. 5, the battery container (
5) is provided with an annular explosion-proof thin wall portion (15) on the bottom portion (5a), and the diameter of the thin wall portion (15) is 19 to 87% of the outer diameter of the bottom portion (5a) of the battery container (5). It is set.

As a result, when this battery encounters an abnormal situation such as being exposed to high temperature heating or being charged at a high voltage, and the internal pressure of the battery begins to rise abnormally, the thin part 051
The explosion-proof function activates when the battery is destroyed under pressure within a safe range, preventing the battery from bursting under high pressure, that is, exploding, and when there is no abnormal situation, the explosion-proof function activates and Constructed to prevent loss of functionality.

FIG. 7 is a sectional view showing still another embodiment of the flat sealed battery of the present invention, and FIG. 8 is a schematic bottom view of the battery shown in FIG. 7.

The battery shown in FIG. 7 uses a sealing body 070 in which the sealing plug side and the sealing plate 070 of the battery shown in FIG. Axis of force (1
7a) is press-fitted into the electrolyte injection port 02+, and the sealing body θ'7
) is connected to the bottom (5) of the battery container (5).
5a) is welded with a carbon dioxide laser. In other words,
The electrolyte inlet 02) is temporarily sealed by press-fitting the shaft (17a) of the sealing body 07), and the head (17b) of the sealing body Q7) is temporarily sealed.
) is completely sealed by welding the outer periphery of the battery container (5) to the bottom (5a) of the battery container (5). Except for the above points, the battery shown in FIG. 7 is constructed almost the same as the battery shown in FIG. 1.

Therefore, in the battery shown in FIG. 7 as well, an explosion-proof thin wall portion 05) is provided in an annular shape at the bottom (5a) of the battery container (5), and the diameter of the thin wall portion (15) is equal to the battery capacity i! 5(
5) is set to 19 to 87% of the outer diameter of the bottom (5a).

Therefore, when this battery encounters an abnormal situation such as being exposed to high-temperature heating or being charged at a high voltage, and the internal pressure of the battery begins to rise abnormally, the thin wall portion 0ω
The explosion-proof function activates when the battery is destroyed under pressure within a safe range, preventing the battery from bursting under high pressure, that is, exploding, and when there is no abnormal situation, the explosion-proof function activates and Constructed to prevent loss of functionality.

In the above embodiment, the insulating layer (8) was made of glass, but
The insulating layer (8) may be made of ceramic instead of glass. In addition, in the examples, lithium was used as the negative electrode active material and thionyl chloride was used as the positive electrode active material, and a lithium-thionyl chloride battery was described, but the negative electrode active material may be an alkali metal other than lithium such as sodium or potassium. In addition to thionyl chloride, the positive electrode active material may also include sulfuryl chloride, phosboryl chloride, etc.
! It may be a liquid oxyhalide at 1 (25'C).

〔Effect of the invention〕

As explained above, in a battery employing a hermetic seal, the bottom (5a) of the battery container (5)
By providing an annular thin-walled part θ0 for explosion protection in the battery container (5) so that the diameter thereof is 19 to 87% of the outer diameter of the bottom (5a), the internal pressure of the battery begins to rise abnormally. When the thin wall part a9 breaks under a pressure within a range that can ensure safety, it is possible to prevent the battery from bursting under high pressure, so-called explosion, thereby increasing safety and providing high sealing performance. Moreover, we were able to provide a flat sealed battery with a highly safe explosion-proof function.

[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. Fig. 3 is a cross-sectional view showing the battery container used in the battery shown in Fig. 1 sealed with a sealing plate, and Fig. 4 is an enlarged view of the thin section provided at the bottom of the battery container and its surroundings. FIG. 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. FIG. 7 is a sectional view showing still another embodiment of the flat sealed battery of the present invention, and FIG. 8 is a schematic bottom view of the battery shown in FIG. 7. (1)... Negative electrode, (2)... Type of work, (3)...
・Separator, (4)... Electrolyte, (5)... Battery container, (5a)... Bottom, (6)... Battery lid,
<7)...Body, (8)...Insulating layer, (9)
...terminal, Q2)...electrolyte inlet, 00...
・Annular thin-walled part 7/. Fig. 3 Part Fig. 4 5a Bottom No. 1 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). An electrolyte injection port (12) is provided in the center of the bottom (5a) of 5), and the electrolyte injection port (12) is sealed after the electrolyte is injected;
Moreover, an annular thin-walled part (15) for explosion-proofing is provided at the bottom (5a) of the battery container (5), and the annular thin-walled part (15)
) has a diameter of 19 times the outer diameter of the bottom (5a) of the battery container (5).
A flat sealed battery characterized in that the battery is 87%.