JPH07105219B2 - Non-aqueous liquid active material battery - Google Patents

Description

TECHNICAL FIELD The present invention relates to a non-aqueous liquid active material battery 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 battery usage function. .

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,
No. 26460), these cannot be applied to a non-aqueous liquid active material battery from the viewpoints of punch durability for groove formation and explosion-proof performance, as described in detail below.

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 portion is maintained to some extent, it is possible to develop a highly safe explosion-proof function for the battery by causing a fracture fracture from the end of the groove bottom with a relatively low pressure. The applicant has already applied for a patent (Japanese Patent Application No. 61-228760).

However, even if the groove for imparting the explosion-proof function is formed as described above, the explosion-proof function may not operate normally depending on the size thereof. In other words, the length of the groove plays an important role in ensuring that the explosion-proof function is normally exerted. For example, if the length of the groove is extremely short, the explosion-proof function does not operate and the battery bursts. If the groove length becomes too long, on the other hand, the explosion-proof function will operate under normal operating conditions, or the strength of the bottom of the battery container will decrease, and There is a problem that the pressing portion easily breaks the battery container.

[Problems to be solved by the invention]

The present invention solves the problem that the explosion-proof function of the above-mentioned conventional battery may not operate normally, can exhibit a stable explosion-proof function, and the battery container is easily destroyed by pressing from the outside of the battery. It is an object of the present invention to provide a non-aqueous liquid active material battery that does not exist.

[Means for solving problems]

The present invention specifies the groove length for imparting the explosion-proof function to the battery to 29 to 71% with respect to the outer diameter of the battery container, thereby stably operating the explosion-proof function and under normal use conditions. It prevents the explosion-proof function from operating and the destruction of the battery container due to external pressure.

This will be described in detail below. That is, when the battery is exposed to abnormally high temperature heating or an abnormal voltage is applied to the battery and the internal pressure of the battery rises abnormally,
The first change occurs at the bottom of the battery container, where pressure is most concentrated and subject to gradual expansion. Therefore, in the above-mentioned Japanese Patent Application No. 61-228760, a cross-shaped groove is formed in the bottom of the battery container so that a fracture fracture occurs from the end of the groove to reduce the internal pressure of the battery and exert an explosion-proof function. I am trying to do it. However, according to the studies made by the present inventors, the pressure at which the fracture occurs is greatly changed depending on the ratio of the groove length to the outer diameter of the battery container. In other words, even if the thin part for explosion protection is the same, if the length of the groove is short, the pressure at which fracture breakage of the thin part occurs is high,
Further, if the length of the groove becomes long, even if the pressure is low, the fracture of the thin portion will occur.

Therefore, in the present invention, the relationship between the length of the groove and the outer diameter of the battery container is examined, and the length of the groove is set to be 29
By specifying to be 71%, the explosion-proof function can be stably exerted and the battery container is not easily broken by the pressure from the outside of the battery.

〔Example〕

 Hereinafter, the present invention will be described in more detail with reference to Examples.

A groove having an inverted trapezoidal cross section as shown in FIG. 2 was formed in a cross shape at the bottom of a cylindrical battery container having a bottom and a diameter of 14 mm and a height of 47 mm made of a stainless steel plate having a thickness of 0.3 mm.

As shown in FIG. 1, the planar shape of the groove is a cross shape in which two grooves 3, 3 having the same length intersect at the center. Groove 3
The length B of the groove is changed by changing the size of the cross press die, and the ratio of the length of the groove 3 to the outer diameter A of the battery container 1, that is, B / A is 0.25, 0.29, 0.43, 0.57, 0.71 and
A value of 0.86 was also prepared, that is, 0, that is, a groove was not formed.

The cross-sectional shape of the groove is, as shown in detail in FIG. In terms of shape, the expression "inverted trapezoidal shape" represents the shape when the groove bottom portion 3a is arranged on the lower side. ), The formation angle θ of the groove is 60 °, the bottom 3a of the groove is flat, and the explosion-proof thin-walled portion 4 (that is, The thickness t of the portion thinned by the formation of the groove 3) is 0.07 mm, and its width W is 0.
It is 15 mm.

The relationship between the pressure when water pressure is introduced and pressure is applied to these battery containers and the swelling of the bottom of the battery container is as shown in FIG.

The horizontal axis of FIG. 5 represents the pressure applied to the battery container, and the vertical axis represents the swelling of the bottom of the battery container. In FIG.
The ratio (B / A) of the groove length B to the outer diameter A of the battery container is 0.
(That is, without grooves), the ratio is 0.29, 0.4
The relationship between the pressure and the swelling of the bottom of the battery container in the case of 3, 0.57 and 0.86 is shown. And, the mark "○" indicates that the thin portion provided at the bottom of the battery container was ruptured due to the formation of the groove, and the mark "X" indicates that the bottom of the battery container was ruptured. As is clear from FIG. 5, at the same pressure, the ratio of the groove length B to the outer diameter A of the battery container (B / A)
When the value is small, the swelling of the bottom of the battery container is small, and as the ratio of the length of the groove to the outer diameter of the battery container increases, the swelling of the battery container bottom at the same pressure increases, and the swelling increases to 1.8 to 2.0 mm When it reaches the limit, the thin wall for explosion protection cleaves. It is considered that this is because if the ratio (B / A) of the groove length B to the outer diameter A of the battery container is large, the pressure resistance of the bottom portion of the battery container is lowered and the battery container is swollen quickly. In addition, in the case where the groove is not formed, the bulge of the bottom part under pressure is smaller than that in the case where the groove is formed, and the pressure is 270 kg / cm ²
When it reached, the bottom burst with a loud popping sound.

Fig. 6 shows the ratio of the groove length B to the outer diameter A of the battery container (B /
A) and showing the relationship between the cracking pressure of the explosion-proof thin portion provided at the bottom of the battery container by the formation of the groove,
In the figure, · indicates the cracking pressure of the explosion-proof thin-walled part when the ratio (B / A) of the groove length B to the outer diameter A of the battery container is 0.29, 0.43, 0.57, 0.71 and 0.86, × The mark does not form and shows the pressure when the bottom of the battery container bursts. The ratio of the groove length B to the outer diameter A of the battery container (B / A)
Is connected by a dotted line a between 0 and 0.29, and is connected by a solid line b between the ratio of 0.29 and 0.86.

By the way, it is a problem that it is appropriate to set the pressure at which the explosion-proof function of the battery operates, but as described above, since the bottom part of the battery container bursts at 270 kg / cm ² , The upper limit of the operating pressure is preferably set to about 200 kg / cm ² , more preferably about 180 kg / cm ² . Further, it is hardly increased to 10 kg / cm ² or more at up to at most 5 kg / cm ² about the internal pressure of the battery under normal use conditions. Explosion-proof function is 20 kg / cm ² , more desirably even considering slight variations and corrosion during long-term storage.
If it is set to operate at about 30 kg / cm ² or more, the explosion-proof function will not operate unless an abnormal situation occurs.

From the above viewpoint, if the operating pressure of the explosion-proof function, that is, the breaking pressure of the thin wall for explosion-proof is set to 30 to 180 kg / cm ² , the ratio of the groove length B to the outer diameter A of the battery container at that time (B / A)
Is calculated as 25 to 88% from Fig. 6. That is, the alternate long and short dash line c in FIG. 6 indicates that the cracking pressure of the explosion-proof thin portion is 180 k.
In the case of g / cm ² , the ratio of the groove length B to the outer diameter A of the battery container when the cleavage pressure of the thin wall portion is 180 kg / cm ² from the intersection of the dashed line c and the dotted line a (B / A) is about 0.25. Also, the dashed-dotted line d in FIG. 6 shows the case where the explosion-proof thin-walled portion has a cleavage pressure of 30 kg / cm ² , and the thin-walled portion has a cleavage pressure of 30 kg / cm ² from the intersection of the dashed-dotted line d and the solid line b. The ratio (B / A) of the groove length B to the outer diameter A of the battery case is about 0.8.
8

FIG. 3 shows an AA-size thionyl chloride-lithium battery assembled using the battery container shown in FIGS.
Each component of this battery will be described as follows.

Reference numeral 1 is a battery container, and the bottom 2 of the battery container 1 has a first
As shown in FIGS. 2 to 2, the groove 3 is formed in a cross shape, and by forming the groove 3, the bottom portion 2 of the battery container 1 is partially thinned,
An explosion-proof thin portion 4 is provided. 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 Reference numeral 12 denotes a separator, which is made of glass fiber non-woven fabric and has a cylindrical shape, and separates the cylindrical negative electrode 11 and the cylindrical positive electrode 13 from each other. 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 made of stainless steel and whose raised outer peripheral portion is joined to the opening end of the battery container 1 by welding.
A glass layer 16 is provided between the positive electrode terminal 17 and the inner peripheral side of the glass layer 16. The glass layer 16 insulates the battery lid 15 and the positive electrode terminal 17, 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 is the positive electrode terminal.
The outer peripheral surface of 17 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, this electrolytic solution 18 is a solution of lithium aluminum tetrachloride as a supporting electrolyte in 1.2 mol / mol in thionyl chloride, and thionyl chloride is the solvent of the electrolytic solution as described above, and in this battery This is a positive electrode active material, and the thionyl chloride and the negative electrode are formed on the surface of the positive electrode 13.
A reaction occurs with the lithium ions ionized from 11.
Further, 19 and 20 are a bottom separator and an upper separator made of glass fiber nonwoven fabric, respectively, and 21 is an air chamber.

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. 1 before the battery is assembled (however, FIG. 1 shows the battery container in an inverted state. , The bottom 2 is on the upper side), and a groove 3 having a cross shape in a plan view is formed in the center of the bottom 2 as shown in FIG. 1 (a). As shown in detail in FIG. 2, the groove 3 has an inverted trapezoidal cross-sectional shape with a flat bottom portion 3a, a groove forming angle of 60 °, and a thin portion 4 provided by the formation of the groove 3. The thickness t is 0.07 mm and the width W is 0.15 mm.

The length of the groove is variously changed, and the ratio (B / A) of the length B of the groove to the outer diameter A of the battery container is 0.25, 0.29, 0.43, 0.5.
It is set to 7, 0.71, 0.86, 0.93 and 0 (that is, when the groove is not provided).

These batteries were subjected to a high temperature heating test as shown below, and the results are shown in Table 1. The high temperature heating test was carried out by placing the battery in an electric muffle furnace, heating the battery at a temperature rising rate of 30 ° C./min, and examining the operating state of the explosion-proof function at that time.

Further, in order to investigate the strength against the pressing force from the outside of the battery, a cylindrical rod having a tip diameter of 5 mm is pressed from the outside of the battery with a load of 10 kg at the center of the bottom of the battery container, and the thin portion of the battery container is broken. I checked whether or not. The results are also shown in Table 1.

The number of samples tested was 10 in each case. In the operation status of the explosion proof function in Table 1, the denominator shows the number of samples tested and the numerator shows the number of samples with the explosion proof function activated. Also, in the bottom pressing strength of the battery container in Table 1, the denominator indicates the number of test samples, and the numerator indicates the number of samples in which the thin portion was broken.

As shown in Table 1, regarding the explosion-proof function, when the ratio of the length B of the groove to the outer diameter A of the battery container (B / A) is 0, that is, when the groove is not provided, all samples are , The explosion-proof function did not work, and the battery container ruptured at a temperature of 300 to 350 ℃ with a loud breaking sound. And the above ratio (B / A) is 0.25
Then, out of the 10 test pieces provided for the test, 7 of them had the explosion-proof function activated, but 3 of them did not operate the explosion-proof function and the battery container ruptured.
This is because the length of the groove for giving the explosion-proof function is short, the pressure resistance of the battery container is too strong, the battery temperature rises to near 300 ° C, and even if the internal pressure rises considerably, the thin-walled part for explosion-proof is torn open. It is thought that this is because something that did not occur occurred.
The ratio (B / A) of the groove length B to the outer diameter A of the battery container is 0.2.
Above 9, all batteries became explosion-proof and no damage to the batteries occurred. The operating temperature of the explosion-proof function was 170 to 230 ° C when the ratio (B / A) was 0.29 to 0.71, but the ratio of the groove length B to the outer diameter A of the battery container (B / A) was When it increased, the operating temperature decreased, and when the ratio (B / A) was 0.93, there were some that operated at 120 ° C. Considering that the battery temperature may reach 120 ° C even under normal use, a battery with a ratio (B / A) of the groove length B to the outer diameter A of the battery container of more than 93% is considered to be an abnormal situation. It is considered that the explosion-proof function may operate during normal times.

On the other hand, the test results regarding the pressing strength of the bottom of the battery container show that the ratio of the groove length B to the outer diameter A of the battery container (B / A)
From around 0.86, the resistance against external pressure weakened, and the pressure from the outside of the battery caused the bottom of the battery container to break.

From the above results, the groove length B with respect to the outer diameter A of the battery container
It is considered preferable to set the ratio (B / A) of 0.29 to 0.71, that is, the groove length to 29 to 71% of the outer diameter of the battery container.

FIG. 4 shows an AA-type thionyl chloride-lithium battery. In this battery, a protrusion 2a is provided in the center of the bottom 2 of the battery container 1, and an explosion-proof function is provided at the protrusion 2a. The groove 3 for giving is formed, and the other structure is the same as that of the battery shown in FIG.

This is because the mounted battery often has a protrusion on the bottom of the battery container to facilitate connection to the negative terminal. This is for confirming that there is no difference from the result regarding the bottom pressing strength of the container. In the battery shown in FIG. 3, the convex portion was not provided at the bottom of the battery container. When the convex portion was provided, the length of the groove was increased to obtain the test results shown in Table 1. This is because it is difficult to change.

The ratio (B / A) of the groove length B to the outer diameter A of the battery container is 0.2
We are doing about 9, 0.43, 0.57. The battery container 1
The protruding part 2a provided on the bottom part 2 of the is 8.5 mm in diameter and 0.5 mm in height.
Is. The high-temperature heating test method and the method for measuring the bottom pressing strength of the battery container are the same as those described above, and the test results are shown in Table 2.

As is clear from the results shown in Table 2, the operating conditions of the explosion-proof function and the bottom pressing strength of the battery container are different from those of the battery container shown in Table 1 which is not provided with a protrusion. There was no.

In the above embodiment, the forming angle θ of the groove 3 is 60 °, the thickness t of the thin portion 4 is 0.07 mm, and the width W of the thin portion 4 is 0.15 mm. However, the forming angle θ of the groove 3 is generally 50 to 50 mm. The thickness t of the thin portion 4 is generally in the range of 0.04 to 0.12 mm, and the width W of the thin portion 4 is generally 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, but a plurality of grooves may be used as long as they intersect at at least one position, and the planar shape thereof 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. 7 (a)), an asterisk (*) shape (see FIG. 7 (b)) and the like can be mentioned. 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 length of the groove for imparting the explosion-proof function to the battery is 29 to 71% of the outer diameter of the battery container, thereby stably exhibiting the explosion-proof function, and the battery. It was possible to prevent the battery container from being easily broken by pressing from the outside.

[Brief description of drawings]

FIG. 1 shows a state in which a battery container used for the battery of the present invention is inverted, FIG. 1 (a) is a plan view thereof, and FIG. 1 (b) is an X of FIG. 1 (a). It is a sectional view taken along the line X-. FIG. 2 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. 3 shows an embodiment of the present invention and is a sectional view showing a thionyl chloride-lithium battery assembled using the battery container shown in FIGS. FIG. 4 is a sectional view showing another embodiment of the present invention. FIG. 5 is a diagram showing the relationship between the pressure when a pressure is applied to the battery container and the bulging of the bottom of the battery container. FIG. 6 is a diagram showing the relationship between the ratio (B / A) of the groove length B to the outer diameter A of the battery container and the cleavage pressure of the thin portion of the battery container.
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, A ... outer diameter of battery container, B ... groove length

 ─────────────────────────────────────────────────── ─── 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 is an oxyhalide type liquid active material such as thionyl chloride, sulfuryl chloride or phosphoryl chloride, an alkaline metal such as lithium, sodium or potassium is used for the negative electrode, and the battery container is hermetically sealed. In the non-aqueous liquid active material battery described above, the explosion-proof thin wall portion is provided by forming a plurality of grooves at the bottom of the battery container, the bottom having a flat cross-section inverted trapezoidal shape and at least one intersection. A non-aqueous liquid active material battery, wherein the length of each of the plurality of grooves is 29 to 71% of the outer diameter of the battery container.