JPH07105216B2 - Non-aqueous liquid active material battery - Google Patents

Description

The present invention relates to a non-aqueous liquid active material having an explosion-proof function.

[Conventional technology]

A battery using an oxyhalide-based liquid such as thionyl chloride, sulfuryl chloride, or phosphoryl chloride as a positive electrode active material typified by a thionyl chloride-lithium battery and using an alkali metal such as lithium, sodium, or potassium for the negative electrode Since active materials and alkali metals react very easily with water, a completely sealed structure that seals the battery container with a hermetic seal has been adopted.

Batteries employing such a hermetic seal have the advantages of high airtightness and excellent storability, but on the other hand, because of their high airtightness, they are exposed to high temperature heating and are charged at high voltage. When an abnormal situation such as the above is encountered, the internal pressure of the battery rises abnormally and the battery explodes, creating a loud popping noise, and the battery contents may scatter around and contaminate the equipment using the battery. .

Therefore, in this non-aqueous liquid active material battery, it is possible to provide the battery with an explosion-proof function by forming a cross-shaped groove in the bottom of the battery container, as is proposed for an alkaline battery having a similar sealed structure. Will also need to be incorporated.

However, the explosion-proof groove proposed in the alkaline battery has a V-shaped cross-section, and its tip, that is, the groove bottom is sharpened (see, for example, Japanese Utility Model Publication No. 58-17).
No. 332), or a V-shaped cross section with 0.1 to
It has a roundness of 0.2mmR (for example,
As described in detail below, these cannot be applied to a non-aqueous liquid active material battery from the viewpoint of durability of the punch for groove formation and the explosion-proof performance.

That is, the cross-sectional shape proposed for alkaline batteries is V
Although a groove with a sharp groove bottom can be expected to have a notch effect, the tip of the groove-forming punch is immediately damaged when the groove is formed by press molding, especially for non-aqueous liquid active material batteries. In order to withstand the strong corrosiveness of the positive electrode active material, the battery container uses corrosion-resistant metal with high hardness such as stainless steel. Due to the variation in the shape of the V-shaped groove, it cannot be industrially adopted. On the other hand, the V-shaped cross-section with rounded groove bottom is
It is thought that the punch will be less damaged, but if the bottom of the groove is rounded, the effect of simply making it thinner will be exhibited, and additional effects such as a notch effect will hardly be added, so Unless the thickness of the thin section is very thin, the thin section does not break within the safe pressure range.If the thin section is thin, the thin section may be corroded during storage and the battery function may be lost. There is.

Therefore, the shape of the groove formed in the bottom of the battery container is an inverted trapezoidal cross-section with a flat bottom, and the tensile force due to the internal pressure of the battery and the tensile force due to bending are applied to the ends of the groove bottom. Even if the thickness of the thin wall is maintained to some extent, it is possible to develop a battery with a highly safe explosion-proof function so that the fracture at the end of the groove bottom will occur at a relatively low pressure. The applicant has already applied for a patent (Japanese Patent Application No. 61-228760).

However, the important factor that activates the explosion-proof function is the pressure applied to the air chamber in the battery at high temperatures, and it is not always sufficient to consider the shape of the groove for explosion-proof and the thickness of the thin-walled part. Can't get

For example, when thionyl chloride is used as the positive electrode active material, the vapor pressure of thionyl chloride is not much different from that of water at high temperature,
Volume expansion coefficient of 1 × 10 ^-3 deg ^-1 water volume expansion coefficient of 0.207 × 10
Nearly 5 times larger than ^-3 deg ^-1 . Therefore, when the battery is exposed to high temperatures and the volume of thionyl chloride expands, the pressure rise in the air chamber, which is the sum of the partial pressure of air and the vapor pressure of thionyl chloride, is the volume of the air chamber set when the battery is manufactured. It is significantly different from the above, and it is more rapid than the internal pressure rise in a battery using an aqueous electrolyte such as an alkaline battery. Therefore, if the volume of the air chamber is not appropriate, the explosion-proof function may operate even under normal use conditions, and the battery function may be lost.

[Problems to be solved by the invention]

The present invention has a problem in that the above-mentioned conventional technology cannot provide a highly safe explosion-proof function to the battery, or the explosion-proof function is activated even under normal use conditions and the battery function is lost. It is an object of the present invention to provide a non-aqueous liquid active material battery that does not operate in an explosion-proof function under normal use conditions and has a highly safe explosion-proof function.

[Means for solving problems]

The present invention examines the relationship between the volume of the air chamber and the pressure in the air chamber, specifies the volume of the air chamber to 7.5% to 15% of the total battery internal volume, and the thickness of the thin portion for explosion protection and By specifying the groove shape for forming the thin portion, the explosion-proof function with high safety is imparted to the battery while preventing the operation of the explosion-proof function under normal use conditions.

In the present invention, the reason why the volume of the air chamber in the battery is specified to be 7.5 to 15% of the total internal volume of the battery is based on the following experimental results.

FIG. 4 shows the relationship between the internal pressure of the air chamber and the temperature when the volume of the air chamber of an AA thionyl chloride-lithium battery having an outer diameter of 14 mm and a height of 52 mm was changed. The battery will be described later in detail with reference to FIG. 1, but an air chamber 21 is provided in the upper part of the battery.

In Figure 4, the volume of the air chamber of the battery is 400μ, 450μ
, 500μ, 550μ, 600μ, 700μ, 750μ, 8
The relationship between the pressure and temperature in each air chamber when changing to 00μ, 850μ, 900μ is shown, but the temperature reaching the same pressure increases as the volume of the air chamber increases. Therefore, from FIG. 4, even if the explosion-proof function is set to operate at a certain pressure by controlling the thickness of the thin portion for explosion-proof, the operating temperature changes greatly when the volume of the air chamber changes. I understand.

For example, when the volume of the air chamber is 400μ, the internal pressure of the air chamber at 120 ℃ reaches 300kg / cm ² , and the burst pressure of the battery container is 2
Considering that it is 00 to 300 kg / cm ² (This battery has a strong sealing part, so if the battery does not have an explosion-proof function, the battery will burst if the battery container bursts). It must be set to activate the explosion proof function. However, because of the characteristics of this battery, that is, the characteristic that this battery can be used at a higher temperature than other batteries, 120 ° C is a temperature that can be taken under normal use conditions. It is not preferable that the explosion-proof function operates below. However, the volume of the air chamber is 450μ
Then, the internal pressure at 120 ℃ will be about 15 kg / cm ² , and if the explosion-proof function is set to operate at this pressure, the explosion-proof function will operate under normal use conditions and the battery function will be lost. Disappears. The internal pressure of the battery at 20 ° C is about 1.3 kg / cm ² , and the internal pressure at 100 ° C is 3 to 4 kg / cm ² .

FIG. 5 shows the relationship between the volume of the air chamber of this battery, the quantity of electricity of the negative electrode (lithium) that can be filled, and the quantity of electricity obtained by discharging.

The horizontal axis of FIG. 5 shows the volume of the air chamber of the battery, the vertical axis shows the amount of electricity, the solid line in FIG. 5 shows the amount of electricity charged in the negative electrode, and the dotted line shows the amount of electricity discharged. In this battery, the amount of electricity discharged corresponds to about 93% of the amount of electricity charged to the negative electrode.

For this AA thionyl chloride-lithium battery,
It is required by the user (user) to maintain a discharge electricity amount of 2000 mAh or more. Therefore, in order to secure a discharge electricity amount of 2000 mAh or more, the volume of the air chamber needs to be 900 μ or less as shown in FIG.

From the above situation, it is considered that the appropriate volume of the air chamber is 450 to 900μ. Since the total battery internal volume of this battery is 6 ml, the air chamber volume of 450 to 900 μ corresponds to 7.5 to 15% of the total battery internal volume.

Next, considering the pressure at which the explosion-proof function operates, if the lower limit of the above-mentioned air chamber volume is 450μ and it is tried to make the explosion-proof function operate at 120 ° C or higher, the operating pressure is 15 kg / The pressure may be about cm ^2, but the operating pressure is preferably set to 20 kg / cm ² or more in order to enhance safety. Therefore, ²⁰ to 200 kg / cm ² is considered appropriate as the pressure range in which the explosion proof function operates.

Next, in order to operate the explosion-proof function in the pressure range as described above, there is a problem as to how thick the thin portion for explosion-proof should be.

FIG. 6 shows the bottom portion 2 of the battery container 1 as shown in FIGS.
The thin-walled portion 4 is formed by forming the cross-shaped groove 3 in the thin-walled portion, and the thickness of the thin-walled portion when the pressure is applied to the battery container having the thin-wall portion 4 for explosion-proof from the inside to the outside. It shows the relationship with the pressure when the thin wall portion is fractured by fracture and the explosion-proof function is activated.

The horizontal axis of Fig. 6 shows the thickness of the thin portion for explosion protection, and the vertical axis shows the working pressure of the explosion-proof function. As shown in Fig. 6, the thickness of the thin portion is 45 µm and the working pressure is 20 kg. / cm ^2, and the more the operating pressure thickness at 120μm thin portion is 200 kg / cm ^2, to operate the explosion-proof function at a pressure of 20 to 200 kg / cm ^2, and 45~120μm the thickness of the thin portion It is appropriate to do. Also, the explosion-proof function is more preferable range, that is, 50
To operate at to 100 kg / cm ² approximately, the thickness of the thin portion 60
It is preferably about 90 μm.

〔Example〕

While referring to the above knowledge, the thickness of the thin wall for explosion protection is 30μ.
m, 45 μm, 70 μm, 120 μm, and 150 μm, to prepare a battery container.

Using the above 5 types of battery containers, the volume of the air chamber is 400μ
, 450μ, 650μ, 900μ and 950μ thionyl chloride-lithium batteries were made.

The structure of the battery is as shown in FIG. Each component of the battery will be described as follows.

Reference numeral 1 denotes a battery container, and a groove 2 for imparting an explosion-proof function to a battery is formed in a bottom portion 2 of the battery container 1 as shown in detail in FIGS. Battery container 1
The bottom portion 2 of the is partially thinned to form an explosion-proof thin portion 4. Reference numeral 11 denotes a negative electrode made of an alkali metal, which is formed by pressing a lithium plate onto the inner peripheral surface of the battery container 1 in this embodiment. Therefore, in this battery, the battery container 1 functions as a negative electrode terminal. Have
12 is a separator, and this separator 12 is made of glass fiber nonwoven fabric and has a cylindrical shape, and the cylindrical negative electrode.
11 and the cylindrical positive electrode 13 are separated. The positive electrode 13 is made of a carbon porous molded body formed of carbonaceous material containing acetylene black as a main component, and 14 is a positive electrode current collector made of a stainless steel rod. Reference numeral 15 denotes a battery lid, which is formed of stainless steel, and the raised outer peripheral portion is joined to the open end of the battery container 1 by welding, and the positive electrode terminal is provided on the inner peripheral side of the battery lid 15.
A glass layer 16 is provided between the glass layer 16 and The glass layer 16 insulates the battery lid 15 and the positive electrode terminal 17 from each other, and at the outer peripheral surface thereof, the constituent glass is fused to the inner peripheral surface of the battery lid 15, and at the inner peripheral surface, the constituent glass of the positive electrode terminal 17 is formed. The outer peripheral surface is fused and sealed between the battery lid 15 and the positive electrode terminal 17, and the opening of the battery container 1 is sealed by a so-called hermetic seal. The positive electrode terminal 17 is made of stainless steel and has a pipe shape at the time of battery assembly, and is used as an electrolyte injection port. It is welded and sealed. 18 is an electrolytic solution, which is a solution of thionyl chloride in which 1.2 mol / l of lithium aluminum tetrachloride as a supporting electrolyte is dissolved.Thionyl chloride is a solvent of the electrolytic solution as described above, and in this battery, It is also a positive electrode active material, and on the surface of the positive electrode 13, this thionyl chloride reacts with lithium ions ionized from the negative electrode 11. Reference numerals 19 and 20 are a bottom separator and a top separator made of glass fiber non-woven fabric, respectively. 21 is an air chamber provided in the upper part of the battery, and the volume of the air chamber 21 is 400 μm or 4 μm depending on the battery as described above.
It has been changed to 50μ, 650μ, 900μ and 950μ.

The battery container 1 is made of a stainless steel plate having a thickness of 0.3 mm, and has a bottomed cylindrical shape as shown in Fig. 2 before the battery is assembled (however, Fig. 2 shows the battery container in an inverted state. The bottom 2 is on the upper side, as shown),
A groove 3 having a cross shape in a plan view is formed in the protruding portion 2a at the center of the groove as shown in FIG. 2 (a). As shown in detail in FIG. 3, the groove 3 has an inverted trapezoidal cross-section with a flat bottom 3a ( The expression "inverted trapezoidal shape" represents the shape when the groove bottom portion 3a is arranged on the lower side. ), And the groove forming angle θ is set to 60 °. 4 is the thin part,
The thin portion 4 is provided in a cross shape on the bottom portion 2 of the battery container 1 by forming the groove 3 and has a width W of the thin portion 4.
Is 0.15 mm, and its thickness t is changed to 30 μm, 45 μm, 70 μm, 120 μm, 150 μm depending on the battery container as described above. In this embodiment, the protruding portion 2a is provided at the center of the bottom portion 2 of the battery container 1 so that the lead terminal can be easily attached.
Since the groove 3 is provided in the protruding portion 2a, the protruding portion 2a is not always necessary, and the bottom portion 2 of the battery container 1 may be flat. In that case, the groove 3 may be formed in the central portion of the flat bottom portion 2 of the battery container 1, but even in that case, the explosion-proof function is particularly improved as compared with the case where the groove 3 is formed in the protruding portion 2a. There is no such thing as a drop.

These batteries were heated from room temperature to 500 ° C at a heating rate of 20 ° C / min, and the operation status of the explosion-proof function was investigated. The results are shown in Table 1. The X mark in Table 1 indicates that the explosion proof function did not operate and the battery ruptured, and the Δ mark indicates that the explosion proof function operated at a temperature of 120 ° C. or less. Also, ○ indicates 120 ° C
Indicates that the explosion-proof function has been activated after the value exceeded.

As shown in Table 1, in all of the batteries having a thin portion with a thickness of 150 μm, the explosion-proof function did not operate, and the battery ruptured with the side part of the battery container ruptured. This is because, as estimated from the operation test results of the explosion-proof function shown in Fig. 6, the explosion-proof function operates at 300 kg / cm ² or more, so the thin-walled part provided at the bottom of the battery container is fractured and broken. It is considered that this is because the battery bursts before the function operates. Also, the battery with the explosion-proof thin wall thickness of 30 μm has an air chamber volume
When it was 900μ or less, the explosion-proof function operated at the temperature of 120 ° C or less. It is considered that this is because the thin wall portion for explosion protection has a small thickness, so that the thin wall portion is fractured and broken and the explosion protection function is activated when the internal pressure is relatively low. In addition, the explosion-proof function of a battery with an air chamber volume of 400μ was activated at temperatures below 120 ° C. It is considered that this is because the internal pressure becomes extremely large at 120 ° C. or lower, as can be seen from FIG. On the other hand, the thickness of the explosion-proof thin portion is 45 to 120 μm, and the volume of the air chamber is in the range of 450 to 900 μ, that is, the total battery internal volume is 6 ml, so the volume of the air chamber is 7.5% of the total battery internal volume. ~ 15
In the range of 100%, the explosion-proof function operated at temperatures above 120 ° C. By the way, when the thickness of the thin part is 45 μm and the volume of the air chamber is 45 μ, the operating temperature of the explosion-proof function is about 12
At 5 ° C, the pressure at that time is estimated to be about 30 kg / cm ² from Fig. 4. If the thin part has a thickness of 120 μm and the volume of the air chamber is 900 μ, the operating temperature of the explosion-proof function is about 2
At 58 ° C, the pressure at that time is estimated to be about 180 kg / cm ² from Fig. 4.

Although the forming angle θ of the groove 3 is set to 60 ° and the width W of the thin portion is set to 0.15 mm in the above embodiment, the forming angle θ of the groove 3 is preferably in the range of 50 to 80 °. Generally, the width W of the thin portion 4 is preferably in the range of 0.09 to 0.5 mm.

Further, in the above-mentioned embodiment, the case where the cross-shaped groove is formed has been described. However, as long as there are a plurality of grooves and those grooves intersect at at least one location, the planar shape is the same as in the embodiment. In addition to the cross shape shown, for example, the seventh
As shown in the figure, an X shape (see FIG. 7A), a Y shape (see FIG. 7B), an asterisk (*) shape (see FIG. 7C), an H shape (See FIG. 7 (d)). In particular, when the internal pressure is applied to the battery, the center of the bottom of the battery container is most deformed.
A letter shape, an asterisk shape and the like are preferable. Further, the groove is not required to intersect at the middle portion thereof, and the end portions of the groove may intersect, such as a Y shape. The explosion-proof thin-walled portion provided at the bottom of the battery container by forming the groove is not limited to the cross shape illustrated in the embodiment, and may have various planar shapes similar to the groove.

In addition, in the present invention, a plurality of grooves are formed, and the plurality of grooves intersect at at least one position. However, this is achieved by forming a plurality of grooves so that the grooves have intersection points. If this is done, the internal pressure of the battery will be concentrated on the intersection, and the explosion-proof function will operate accurately in response to the increase in the internal pressure of the battery.

〔The invention's effect〕

As described above, in the present invention, the bottom of the battery container,
A groove with an inverted trapezoidal cross section with a flat bottom is formed, and the thickness of the thin wall for explosion protection provided by the groove is 45 to 120 μm.
m, the volume of the air chamber in the battery is 7.5 to 15% of the total volume of the battery
By doing so, it was possible to provide a non-aqueous liquid active material battery having an explosion-proof function that does not operate under normal use conditions and that operates safely.

[Brief description of drawings]

FIG. 1 is a sectional view of a thionyl chloride-lithium battery showing an embodiment of the present invention. FIG. 2 shows the battery container used for the battery shown in FIG. 1 in an inverted state.
Figure (a) is a plan view thereof, and Figure 2 (b) is Figure 2 (a).
3 is a cross-sectional view taken along line XX of FIG. FIG. 3 is an enlarged cross-sectional view of the groove provided in the bottom portion of the battery container and its vicinity in the present invention. FIG. 4 is a diagram showing the relationship between the internal pressure of the air chamber and the temperature when the volume of the air chamber in the AA type thionyl chloride-lithium battery is changed. FIG. 5 is a diagram showing the relationship between the volume of the air chamber and the amount of electricity charged to the negative electrode and the amount of electricity discharged from the AA thionyl chloride-lithium battery. FIG. 6 is a diagram showing a relationship between the thickness of the explosion-proof thin portion of the battery container provided with the explosion-proof thin portion by forming the groove and the operating pressure of the explosion-proof function. FIG. 7 schematically illustrates a planar shape of a groove other than the cross-shaped groove of the battery container used for the battery of the present invention. The upper stage is a schematic front view of each battery container, and the lower stage is a schematic bottom face of each. It is a figure. 1 ... Battery container, 2 ... bottom, 3 ... groove, 3a ... groove bottom, 4 ... thin-walled part, 11 ... negative electrode, 12 ... separator, 13 ... positive electrode, 15 ... battery lid, 16 …… Glass layer, 18 …… Electrolyte, 21 …… Air chamber

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kenichi Yokoyama, 1-88, Torora, Ibaraki-shi, Osaka Prefecture Hitachi Maxell Co., Ltd. Maxel Co., Ltd.

Claims (1)

[Claims] 1. A positive electrode active material comprising an oxyhalide liquid such as thionyl chloride, sulfuryl chloride or phosphoryl chloride, an alkaline metal such as lithium, sodium or potassium as a negative electrode, and a hermetically sealed battery container. In a water-liquid active material battery, at least one cross-section inverted trapezoidal shape with a flat bottom is provided at the bottom of the battery container.
An explosion-proof thin-walled portion is provided by forming a plurality of grooves having intersections of points, and the thin-walled portion has a thickness of 45 to 120 μm.
m, and the volume of the air chamber provided in the upper part of the battery is 7.5 to 15% of the total internal volume of the battery.