JPH07105217B2 - 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 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 easily uses a corrosion resistant metal such as stainless steel, so the damage to the punch becomes more and more severe, and the durability of the punch and damage to the punch are increased. 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 groove bottom is rounded, the effect of simply being thin is exhibited, and the additional effect such as the notch effect is hardly added. 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).

By the way, in a battery using an oxyhalide-based liquid as a positive electrode active material as in the present invention, when the battery is exposed to a high temperature, the internal pressure (internal pressure) of the battery changes as shown in FIG. It is characterized by a sharp increase from around 50 kg / cm ² .

That is, FIG. 5 shows the relationship between pressure and temperature in the battery, where the horizontal axis represents temperature and the vertical axis represents pressure in the battery. In this battery, when the temperature exceeds 170 ° C. The internal pressure rises sharply, the temperature rises to about 50 kg / cm ² at a temperature of 180 ° C, and even when the temperature rises above 50 kg / cm ² , the internal pressure rises sharply even with a slight temperature rise, and the pressure rises sharply.

Therefore, if the battery is actually exposed to a sudden rise in temperature due to a fire, etc.
In some cases, the internal pressure of the battery does not decrease sufficiently, the internal pressure of the battery rises faster than the internal pressure of the battery decreases, and the battery may burst. This is because the area of the opening is too small when the explosion-proof thin part is torn open and the explosion-proof function is about to operate.
It is considered that this is because the separator and the positive electrode of the battery contents block the opening. That is, as shown in FIG. 4 (b), when the thin portion 4 has a narrow width and a small area, the opening area is small even if the internal pressure of the battery is increased and the thin portion 4 is torn to activate the explosion-proof function. Since it is small, the battery contents such as the separator and the positive electrode block the opening. Therefore, when the internal pressure drops slowly and the temperature rises particularly rapidly, the internal pressure of the battery rises faster, leading to battery rupture.

[Problems to be solved by the invention]

The present invention, as described above, in the conventional battery, even if the explosion-proof thin wall portion is cleaved, the opening may be blocked by the battery contents such as the separator and the positive electrode, and the explosion-proof function may not be exhibited. I solved the problem that there was,
It is an object of the present invention to provide a non-aqueous liquid active material battery that can stably exhibit an explosion-proof function even if there is a rapid temperature rise.

[Means for solving problems]

In order to prevent the opening portion from being blocked by the battery contents and preventing the explosion-proof function from being exerted when the explosion-proof thin-wall portion is cleaved, the present invention examines the area of the explosion-proof thin-wall portion, By making the area of the thin portion for use to be 0.7 to 5.2% of the area of the bottom of the battery container, the explosion-proof function can be stably exhibited even when exposed to a sudden temperature rise.

That is, as shown in FIG. 4A, when the width of the explosion-proof thin portion 4 is wide, that is, the area is wide, the thin portion 4 is
When the resin is cleaved, the opening becomes wider, the opening is less likely to be blocked by the battery contents such as the separator and the positive electrode, and the explosion-proof function can be stably exhibited. Therefore, in the present invention, in order to stably exhibit this explosion-proof function, first, it is examined how much the area of the thin wall portion for explosion-proof should be larger than the area of the bottom portion of the battery container. However, the area of the thin wall for explosion protection was specified to be 0.7% or more of the bottom area of the battery container. However, if the width of the thin portion is too wide, the cleavage pressure of the thin portion becomes high, and the explosive function may not be exerted within the desired pressure range. That is, in the cleavage of the thin portion, the internal pressure of the battery rises and the bottom of the battery container swells, and the tensile force due to the internal pressure of the battery and the tensile force due to bending are combined on the end of the bottom of the groove, and the groove bottom It occurs at the end (that is, the end of the thin part), but if the width of the thin part is wide, the stress applied to the end of the groove bottom is dispersed, the cutting effect becomes small, and the desired pressure range No internal cleavage occurs. Therefore, in the present invention, the width of the thin-walled portion is widened, and when the area is widened, the extent to which the explosion-proof function can operate in the desired pressure range is examined, and the thin-walled portion for explosion-proof is examined. The upper limit of the area is specified to be 5.2% of the bottom area of the battery container.

〔Example〕

The width of the thin part is 0.05mm, 0.07mm, 0.1mm, 0.15mm, 0.3mm,
A battery container having a size different from 0.5 mm and 0.6 mm was prepared, and an AA thionyl chloride-lithium battery having a structure shown in FIG. 3 was prepared using the battery container. Each component of the battery will be described as follows.

Reference numeral 1 denotes a battery container, and a groove 3 for imparting an explosion-proof function to the battery is provided in the battery container 1 as described in detail in FIGS.
The bottom portion 2 of the battery container 1 is partially thinned by the formation of the groove 3, and the thin portion 4 is formed. 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
And are isolated. 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 rising outer peripheral portion is joined to the opening end portion of the battery container 1 by welding, and the inner peripheral side of the battery lid 15 is connected to the positive electrode terminal 17 by a glass. The layer 16 is interposed. 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. Positive terminal
17 is made of stainless steel and has a pipe shape at the time of assembling the battery, and is used as an inlet for the electrolytic solution, and its upper end is welded to the upper part of the positive electrode current collector 14 inserted into the hollow part after the electrolytic solution is injected. It has been sealed. 18 is an electrolytic solution, and this electrolytic solution 18 is thionyl chloride in which 1.2 mol / mol 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 a positive electrode. It is also an active material, and on the surface of the positive electrode 13, this thionyl chloride reacts with lithium ions ionized from the negative electrode 11. 19 and 20 are a bottom separator and a top separator made of glass fiber non-woven fabric, respectively.
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 an inverted state of the battery container. 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 projecting portion 2a at the central portion of the, as shown in FIG. 1 (a). As shown in detail in FIG. 2, the groove 3 has an inverted trapezoidal cross-section with a flat bottom 3a ( The shape of the inverted trapezoid is a 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 the thickness t of the thin portion 4 is t.
Is 0.07 mm and its width W depends on the battery case as described above.
0.05mm, 0.07mm, 0.1mm, 0.15mm, 0.3mm, 0.5mm, 0.6mm
It has been changed and, by the length of each groove 3 is 8 mm, than that formed in a cross shape with two, an area of each of the thin portion 4 8 mm ² at this time, 1.1 mm ^2, 1.6 mm ^2, 2.4mm ² , 4.8mm ² ,
It is 8 mm ² and 9.6 mm ² . The bottom area of the battery container is 153.
Since it is 9 mm ² , the area of these thin portions 4 is 0.5%, 0.7%, 0.10%, 1.6% of the bottom area of the battery container,
Equivalent to 3.1%, 5.2%, 6.2%. In this embodiment, the battery container 1 is designed so that the lead terminals can be easily attached.
Since the protrusion 2a is provided at the center of the bottom 2 of the battery, the groove 3 is formed in the protrusion 2a, but the protrusion 2a is not always necessary, and the bottom 2 of the battery container 1 is not necessarily required. 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,
Compared with the case where the groove 3 is formed in the protruding portion 2a, the explosion-proof function is not particularly deteriorated.

The battery was placed in a fire and examined whether the battery exploded with a loud popping sound. The results are shown in Table 1. Further, the internal pressure was applied to the battery container, and the pressure when the thin portion was cleaved was measured, and the results are also shown in Table 1.

As shown in Table 1, when the width W of the thin-walled portion is 0.30 mm or less and the area of the thin-walled portion with respect to the bottom area of the battery container is 3.1% or less, the cleavage pressure of the thin-walled portion of the battery container is in any case. is in the range of 62~80kg / cm ^2, explosion-proof function is 62~80kg
It is thought that it will operate in the range of / cm ² , but when the battery was actually assembled and put into fire, when the area of the thin wall part was 0.5% of the bottom area of the battery container, it was subjected to the test 10
Explosion-proof function was not fully exhibited due to battery rupture in two of the samples, but when the area of the thin part was 0.7% or more of the bottom area of the battery container, rupture in fire disappeared and became stable. Explosion-proof function came to be exhibited. On the other hand, when the width of the thin portion becomes wide and the area of the thin portion relative to the bottom area of the battery container becomes large, the cleavage pressure of the thin portion becomes high,
When the area of the thin portion relative to the bottom area of the battery container was 5.2%, the cracking pressure of the thin portion was 135 kg / cm ² and no fire burst occurred, but the area of the thin portion relative to the bottom surface of the battery container was At 6.2%, the cracking pressure of the thin portion became 280 kg / cm ² , and 6 out of 10 samples burst in fire.

From the above test results, as the area of the thin wall for explosion protection,
It can be said that 0.7 to 5.2% of the bottom area of the battery container is suitable.

Although the forming angle θ of the groove 3 is 60 ° and the thickness t of the thin portion 4 is 0.07 mm in the above embodiment, the forming angle θ of the groove 3 is preferably in the range of 50 to 80 °. The thickness t of the thin portion 4 is generally preferably in the range of 0.04 to 0.12 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. Other than the cross shape shown, for example, the sixth
As shown in the figure, an X shape (see FIG. 6A), a Y shape (see FIG. 6B), an asterisk (*) shape (see FIG. 6C), an H shape (See FIG. 6 (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 area of the explosion-proof thin portion provided at the bottom of the battery container is 0.7% of the bottom area of the battery container.
By setting the content to ~ 5.2%, it is possible to prevent the opening portion from being blocked by the battery contents when the thin-walled portion is cleaved and to stably exhibit the explosion-proof function.

[Brief description of drawings]

FIG. 1 shows the battery container used in the battery of the present invention in an inverted state. 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 schematically shows a state in which the explosion-proof thin portion provided at the bottom of the battery container is cleaved, and FIG. 4 (a) shows a case where the thin portion has a wide width.
Figure (b) shows the case where the width of the thin portion is narrow. FIG. 5 is a diagram showing the relationship between pressure and temperature in the thionyl chloride-lithium battery. FIG. 6 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

Front page continued (72) Inventor Kenichi Yokoyama 1-1-88, Tora, Ibaraki-shi, Osaka Hitachi Maxell Co., Ltd. (72) Inventor Yoshio Uetani 1-1-88, Tora, Ibaraki-shi, Osaka In the company

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.
By forming a plurality of grooves having intersections of points,
A non-aqueous liquid active material battery characterized in that an explosion-proof thin portion is provided, and the area of the explosion-proof thin portion is 0.7 to 5.2% of the bottom area of the battery container.