JPH10334949A - Square nonaqueous electrolyte secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a square nonaqueous electrolyte secondary battery which is superior with respect to safety and corrosion resistance. SOLUTION: A square nonaqueous electrode secondary battery comprises a current cutting-off device for cutting off a current when a pressure inside a battery reaches a cut-off pressure, and a cleavage device for releasing the pressure inside the battery when the pressure inside the battery reaches a cleavage pressure, wherein the cleavage pressure is greater than the cut-off pressure. The current cutting-off device is sealed from the outside by an insulating portion 22, and a cut-off valve 12 constituting part of a conducting path disconnects the conducting path by having a curved shape reversed, when the pressure inside the battery exceeds the cut-off pressure. The cleavage device cleaves a cleavage valve 18 to release the pressure inside the battery directly to the outside, when the pressure reaches the cleavage pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealed nonaqueous electrolyte secondary battery provided with a safety device for preventing the internal pressure of the battery from rising above a predetermined pressure.

[0002]

2. Description of the Related Art In recent years, with the spread of portable devices such as video cameras and boomboxes, demand for secondary batteries which can be used repeatedly instead of disposable primary batteries is increasing.

Most of the secondary batteries currently used are nickel cadmium batteries using an alkaline electrolyte.
However, such an aqueous battery has a low discharge potential,
The battery weight and battery volume are large, and the demand for a battery with high energy density has not been sufficiently satisfied.

Recently, as a battery system satisfying these requirements, a non-aqueous electrolyte secondary battery using a light metal such as lithium as a negative electrode has attracted attention and has been actively studied. Among them, a lithium ion secondary battery using a composite oxide of lithium and a transition metal as a positive electrode active material and a carbonaceous material capable of doping / dedoping lithium ions as a negative electrode active material has a high energy density. It has been partly put into practical use as a secondary battery showing good cycle characteristics.

It has been pointed out that such a lithium ion secondary battery is excellent in energy density and cycle characteristics, but is inferior to an aqueous secondary battery in overcharge characteristics. In other words, when the battery generates heat due to overcharging or a short circuit inside the battery and the internal pressure of the battery becomes abnormally high, not only does the performance of the battery deteriorate, but also electrolyte leakage occurs or the battery is rapidly damaged. There is a risk of doing so.

Therefore, in order to prevent such a situation from occurring, various kinds of safety ensuring means are provided in the battery. For example, when the internal pressure of the battery rises to a predetermined value or more due to overcharging or the like, the conduction path between the power generation element and the external terminal is cut off to cut off the current, thereby stopping the reaction in the battery and thereby reducing the internal pressure of the battery. It has been proposed to provide the battery with a device for preventing the rise of the battery.

[0007]

However, even after the device that cuts off the current by operating the device that cuts off the current flow by cutting the conduction path between the power generating element and the external terminal, the internal pressure of the battery is maintained. May rise. For example, it is conceivable to accidentally put it into an incinerator. In such a case, as described above, the internal pressure of the battery may further increase and the battery may be rapidly damaged.

An object of the present invention is to solve such a problem, and when the internal pressure of a battery increases due to overcharging or the like, the current can be reliably shut off. It is an object of the present invention to provide a highly safe rectangular non-aqueous electrolyte secondary battery in which, when the internal pressure further increases, the battery is reliably released from an abnormal increase in internal pressure to prevent the battery from being rapidly damaged. It is assumed that.

[0009]

In order to achieve the above object, a prismatic nonaqueous electrolyte secondary battery according to the present invention has a current interrupting means for interrupting a current when the battery internal pressure reaches a shutoff pressure; Rupture means for releasing the internal pressure of the battery when the pressure reaches the rupture pressure, wherein the rupture pressure is greater than the cutoff pressure. The current interrupting means is hermetically sealed from the outside by an insulating portion, and when the internal pressure of the battery exceeds the interrupting pressure, the shut-off valve forming a part of the electrical conduction path reverses its curved shape, thereby turning on the conduction path. The breaking means is characterized in that when the breaking pressure reaches the breaking pressure, the breaking valve is broken to release the internal pressure of the battery directly to the outside.

Therefore, the prismatic non-aqueous electrolyte secondary battery according to the present invention shuts off the current when the internal pressure of the battery exceeds a predetermined current interrupting pressure even if the internal pressure of the battery increases for some reason, thereby reliably preventing the internal pressure of the battery from increasing. can do. In addition, even if the internal pressure of the battery further increases despite the interruption of the current, the prismatic nonaqueous electrolyte secondary battery opens the cleavage valve to directly release the internal pressure of the battery to the outside before the battery is rapidly damaged. Because it is open, it is extremely excellent in safety.

Further, the prismatic nonaqueous electrolyte secondary battery according to the present invention has excellent corrosion resistance even in a poor environment because the current interrupting means is sealed off from the outside.

The insulating portion for sealing the current interrupting means from the outside has one end having a substantially semicircular shape and the other end having a rectangular shape, and the insulating portion on the substantially semicircular shape has a terminal insulating property. It is preferable to also serve as As a result, excellent sealing performance, workability,
High insulation can be obtained.

Further, it is preferable that the cleavage means is provided on the substantially semicircular side of the insulating portion and is spaced apart therefrom. Thereby, at the time of assembling the battery, inconveniences such as the cleaving valve being closed by the insulating portion are prevented.

Incidentally, the current interruption pressure is 3 to 15
kg / cm ² , and the cleavage pressure is 12 to 35 kg.
/ Cm ² . In order for the current interrupting means and the cleavage means to operate well, the above range is preferable.

It is preferable that the insulating portion for sealing off the current interruption to the outside is made of butyl rubber. Butyl rubber is preferably used because of its excellent adhesion.

It is preferable that the component constituting the conduction path is formed by plating the outermost surface with gold or palladium. It is preferable that the battery lid has a recess for accommodating the current interrupting means below the terminal, and the inner wall of the recess is preferably insulated. Thereby, even under a bad environment, the internal resistance of the battery is kept constant, and excellent battery characteristics can be maintained.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a prismatic nonaqueous electrolyte secondary battery to which the present invention is applied will be described in detail with reference to the drawings.

A prismatic non-aqueous electrolyte secondary battery to which the present invention is applied has a current interrupting device for interrupting a current when the battery internal pressure reaches a shut-off pressure, and an external battery internal pressure when the battery internal pressure reaches a breaking pressure. A battery lid provided with a cleavage valve that opens to the battery.

A specific example of such a battery lid is shown in FIG. 1 (cross-sectional view), FIG. 2 (plan view), and FIG. 3 (rear view).

That is, as shown in FIGS. 1 to 3, the battery cover has a metal plate-shaped first battery cover 1 having a recess 1a for accommodating the current interrupting device formed substantially at the center thereof. The second battery lid 2 that seals the opening is welded and joined. As shown in FIG. 4, the first battery cover 1 has, on both sides of the concave portion 1a, a cleavage opening 3 for directly opening the battery internal pressure to the outside.
And an electrolyte inlet 4 for injecting the electrolyte into the battery can.
Are formed. More specifically, the structure and assembly of this battery cover will be described. As shown in FIG. 1, a packing 5 made of rubber or the like is laid on the bottom of the concave portion 1a of the first battery cover 1. A sealing sheet 6 made of aluminum foil or the like is placed thereon. On this sealing sheet 6,
Further, the first base 8 having the placement hole 7 is placed. A first terminal 9 penetrates through the first base 8, and a contact 10 is placed so as to surround the head of the first terminal 9. In addition, as the sealing sheet 6, other than aluminum foil, various metal foils and various resin sheets can be used as long as the sheet is deformed by an increase in battery internal pressure.

A spring push 11 is placed in the placement hole 7 of the first base 8, and a disc spring 12 is placed on the spring push 11.
Has been posted. As shown in FIG. 5, the disc spring 12 is formed in a curved shape, and the center of the disc spring 12 projects toward the sealing sheet 6, that is, inside the battery. The material of the disc spring 12 can be appropriately selected from materials having electrical conductivity and spring properties.

Further, on the disc spring 12 and the first base 8, a second base 13 is mounted. A second terminal 14 penetrates through the second base 13, and the second terminal 14 projects outside through a conductive ring 15.
A confirmation hole 16 is formed in the second base 13 at a position above the disc spring 12. Here, both ends of the disc spring 12 are in contact with the contact 10 (the first terminal 9) and the second terminal 14, and the first terminal 9 → the contact 10 → the disc spring 12 → the second terminal 14 Is formed.

As described above, a conduction path from the first terminal 9 → the disc spring 12 → the second terminal 14 is formed in the recess 1a of the first battery cover 1, and the current interrupting device (the disc spring 12) is provided. Be placed.

Here, in order to seal the opening of the concave portion 1a of the first battery cover 1, the second battery cover 2 is
Placed on top and welded. The welding method is not particularly limited, but laser welding is particularly preferred. The second terminal 14 penetrates through the second battery cover 2. A confirmation hole 17 is formed in the second battery lid 2 at a position above the disc spring 12. When the battery is assembled, the disc spring 12 is turned over from the confirmation holes 16 and 17. Can be confirmed.

Then, a cleavage valve 18 is welded to the cleavage opening 3 of the first battery lid 1. As the cleavage valve 18, it is preferable to use a nickel foil or a material obtained by adjusting a cleavage pressure of a nickel foil to a predetermined pressure by etching or electroforming. The welding method is not particularly limited, but laser welding is particularly preferred.

Further, as shown in FIGS. 1 and 3, an insulating case 19 is attached to the first battery cover 1 so as to surround the recess from the rear side. The first terminal 9 penetrates through the insulating case 19, and a pressure detection hole 20 communicating with the sealing sheet 6 is formed. Then, a connection terminal 21 made of electric conductivity is attached to the insulating case 19 so as to be in contact with the first terminal 9. The first terminal 9 is electrically connected to the positive electrode lead via the connection terminal 21.

Finally, an insulating plate 22 is placed on the second battery cover 2 to seal the confirmation hole 17 formed in the second battery cover 2. As shown in FIG. 2, one end of the insulating plate 22 has a substantially semicircular shape and the other end has a rectangular shape, and the semicircular insulating portion may also serve as the insulation of the second terminal 14. . That is, the shape on the left side in the figure is an O-ring shape so as to surround the conduction ring 15 of the second terminal 14, and the shape on the right side in the figure is used to enhance the insulation with the second battery cover 2. The shape should be rectangular. In this case, in order to prevent the cleavage valve 18 from being closed by the insulating plate 22 at the time of assembling the battery, the cleavage valve 18 may be provided on the second terminal 14 side, that is, on the semicircular side of the insulating plate 22. preferable. In this way, the confirmation holes 16 and 17 are inserted into the front rear circular insulating plate 22.
In the case of sealing, excellent sealing performance and high insulation can be realized.

Further, the insulating plate 1 for closing the confirmation hole 17
The conductive tab 23 on the insulating plate 12 while applying pressure
Is provided. Then, the tab 23 and the second terminal 14 are welded, and this tab is used as a positive terminal connected to an external connection terminal.

As described above, the battery lid thus configured is attached to the opening of the battery can 30, as shown in FIG. For this attachment, an insulating packing may be arranged on the outer periphery of the battery lid by welding, and the opening edge of the battery can may be sandwiched and caulked inside the insulating packing.

The battery can 30 houses an electrode body 31 formed by laminating a positive electrode and a negative electrode with a separator interposed therebetween and winding them many times. One end of the positive electrode lead 32 is electrically connected to one end of the connection terminal 21 in order to collect current from the positive electrode. One end of a negative electrode lead 33 is connected to the battery can 30 in order to collect current from the negative electrode.

In the prismatic non-aqueous electrolyte secondary battery having such a configuration, when the pressure in the battery can 30 rises due to overcharging or short-circuiting, the sealing sheet 6 is pushed up by this pressure, Accordingly, the spring push 11 is also pushed up, and this pressure is transmitted to the disc spring 12. When the internal pressure of the battery can 30 reaches the cutoff pressure, the curved disc spring 12 is inverted by this pressure. That is, the disc spring 1 that has been projected to the sealing sheet 6 side until now.
The center of the second 2 protrudes toward the insulating plate 22. This allows
The periphery of the disc spring 12 is separated from the contact 10 and the second terminal 14, the conduction path is cut off, the generation of gas is suppressed, and the rise in the internal pressure of the battery is stopped.

Here, the cut-off pressure at which the current cut-off means operates is preferably ³ to 15 kg / cm ² , and in consideration of durability and use at a high temperature (60 to 90 ° C.), 4 to 10 k.
g / cm ² is more preferred. If the shut-off pressure is less than 3 kg / cm ² , it cannot withstand normal use, and
^If it exceeds ² , the current cutoff time is too late, and there is a possibility that the current may be rapidly broken, which is not preferable.

The control of the breaking pressure is performed by, for example, changing the material and thickness of the disc spring 12.

Incidentally, the internal pressure of the battery can 30 may be further improved even though the conduction path is interrupted. In this case, the cleavage valve 18 provided on the first battery lid 1 is opened, releasing the pressure in the battery can 30 to the outside.
That is, even if the internal pressure of the battery can 30 further increases despite the interruption of the current path, the cleavage valve 18 is opened before the battery is rapidly damaged, and the internal pressure of the battery is released to the outside.

The cleavage pressure at which the cleavage valve 18 operates is preferably 12 to 35 kg / cm ₂ ,
Considering durability, use at high temperature (60-90 ° C),
15-30 is more preferable. Cleavage pressure is 12kg / cm
^{If it is} smaller than ² , the liquid tends to leak after the current is cut off, and 35
If it exceeds kg / cm ² , the cleavage time will be too late,
It is not preferable because there is a possibility of being rapidly damaged.

In particular, the difference between the operating pressure between the breaking pressure and the breaking pressure needs to be 5 kg / cm ² or more.
Practically, it is more preferable to be 10 to ₂₀ kg / cm ₂ .

As described above, the nonaqueous electrolyte secondary battery provided with the current interrupting means and the cleavage means in the battery lid shuts off the current when the internal pressure of the battery exceeds a predetermined current interrupting pressure even if the internal pressure of the battery increases. Ascent can be prevented. Also, if the battery internal pressure rises despite the interruption of the current, the cleavage valve is opened to release the battery internal pressure to the outside, thereby preventing the battery from being rapidly damaged.

Further, the non-aqueous electrolyte secondary battery described above
As described above, since the confirmation hole 17 is sealed by the insulating plate 22 and the disc spring 12 is sealed from the outside, there is no possibility that water or salt may enter the inside of the battery. To prevent Therefore, this non-aqueous electrolyte secondary battery has extremely excellent corrosion resistance even in a poor environment.

The material of the insulating plate 22 for sealing the confirmation hole 17 is not particularly limited.
Butyl rubber or the like having a property of easily adhering to the second lid 2 is preferably used. The shape of the insulating plate 22 is not particularly limited as long as the confirmation hole 17 can be sealed. However, as described above, an insulating plate having one end formed in a semicircular shape and the other end formed in a rectangular shape is preferably used from the viewpoints of airtightness, insulation, and workability.

In the above-described battery lid, the disc spring 1
2. Components constituting a conduction path such as the contact point 10 and the second terminal 14 may be plated with gold or palladium for the purpose of improving corrosion resistance. Further, in the above-described battery lid, the concave portion 1 of the first battery lid 1 is provided in order to enhance the insulating property of the space of the concave portion provided with the conduction path and the current interrupt device.
It is preferable to perform insulation treatment such as Teflon coating on the inside of the battery pack a and on the side of the concave portion 1a of the second battery cover 2. As a result, even when used in a poor environment, the internal resistance of the battery is kept constant, and good battery characteristics are maintained.

The prismatic non-aqueous electrolyte secondary battery of the present invention is characterized by having the battery lid as described above, but has other components similar to those of the conventional non-aqueous electrolyte secondary battery. It can be.

For example, as the negative electrode active material of the non-aqueous electrolyte secondary battery, various materials can be used according to the type of the intended battery, but metal ions, particularly lithium ions, that contribute to the battery reaction can be used. Carbonaceous materials that can be doped and undoped.

For example, as such a carbonaceous material,
A low-crystalline carbonaceous material obtained by firing at a relatively low temperature of 2000 ° C. or less,
Highly crystalline carbonaceous materials processed at nearby high temperatures can be used. For example, pyrolytic carbons, cokes (petroleum coke, pitch coke, petroleum coke, etc.), artificial graphites, natural graphites, carbon black (acetylene black, etc.), glassy carbons, organic polymer material fired bodies (organic The polymer material is placed in an inert gas stream or in a vacuum for 5 minutes.
(Fired at an appropriate temperature of 00 ° C. or more), carbon fiber and the like. Among them, the (002) plane spacing is 3.70 angstroms or more, and the intimacy is 1.70.
g / cc and 7 by differential thermal analysis in airflow.
A low crystalline carbonaceous material having no exothermic peak at 00 ° C. or higher, or a high crystalline carbonaceous material having a high negative electrode mixture filling property and a true specific gravity of 2.10 g / cc or more can be preferably used.

As the positive electrode active material of the non-aqueous electrolyte secondary battery, a metal oxide, a metal sulfide, or a specific polymer can be used as an active material depending on the type of the intended battery. For example, when configuring a lithium ion secondary battery, Li _x MO ₂ (however,
M is one or more transition metals, preferably Co or N
i, at least one of Fe, 0.05 ≦ X ≦
1.10. ) Is preferably used. For example, as the lithium composite oxide, LiCoO ₂ , LiNiO ₂ , LiNi _y Co _(1-y)
O ₂ (provided that 0.05 ≦ X ≦ 1.10, 0 <y <1). Alternatively, LiMn ₂ O ₄ can be used.

The above-mentioned lithium composite oxide is obtained by mixing carbonates such as lithium, cobalt and nickel according to the composition and sintering the mixture in a temperature range of 400 ° C. to 1000 ° C. in an atmosphere containing oxygen. The starting materials are not limited to carbonates, and can be synthesized from hydroxides and oxides.

As the non-aqueous electrolyte used for the non-aqueous electrolyte secondary battery, a conventionally known non-aqueous electrolyte obtained by dissolving an electrolyte in an organic solvent can be used.

Examples of the organic solvent include esters such as propylene carbonate, ethylene carbonate and r-butyrolactone, and ethers such as diethyl ether, tetrahydrofuran, substituted tetrahydrofuran, dioxolan, pyran and derivatives thereof, dimethoxyethane and diethoxyethane. And 3-substituted-2-oxazolidinones such as 3-methyl-2-oxazolidinone, sulfolane, methylsphorane, acetonitrile, propionitrile and the like. These are used alone or in combination of two or more.

As the electrolyte, lithium perchlorate, lithium borofluoride, lithium phosphofluoride, lithium aluminate, lithium halide, lithium trifluoromethanesulfonate and the like can be used.

The non-aqueous electrolyte may be a solid, and in this case, a conventionally known solid electrolyte can be used.

The electrode may be formed by winding a band-shaped electrode formed by applying an active material to a current collector, or by applying or sintering the active material to the current collector. And a plate-like electrode holding an active material may be laminated.

[0051]

The present invention will be described below in detail with reference to examples.

First, in order to examine the effect of sealing the shut-off valve (disc spring) from the outside, Experimental Examples 1 to 5 were used.
Was manufactured.

Experimental Example 1 First, a negative electrode was prepared as follows.

Petroleum pitch was used as a starting material for the negative electrode active material, and after introducing 10 to 20% by weight of a functional group containing oxygen (oxygen crosslinking), the mixture was heated in an inert gas stream at a temperature of 100%.
By firing at 0 ° C., a carbonaceous material having properties close to glassy carbon was obtained. As a result of X-ray diffraction measurement of this material, the 002 plane spacing was 3.76 Å, and the true specific gravity was 1.58 g / cm ^{3 as} measured by a pycnometer. This carbonaceous material was pulverized to obtain a carbonaceous material powder having an average particle size of 10 μm.

[0055] 90 parts by weight of the carbonaceous material powder obtained in this way and polyvinylidene fluoride (PVD) as a binder were used.
F) was mixed with 10 parts by weight to prepare a negative electrode mixture. Next, this negative electrode mixture was dispersed in N-methylpyrrolidone to form a negative electrode mixture slurry (paste).

The negative electrode mixture slurry was applied to both sides of a 10 μm-thick strip-shaped copper foil serving as a negative electrode current collector, dried, and then compression-molded with a roller press to form a strip-shaped negative electrode 1. The band-shaped negative electrode has a mixture thickness of 8 on both sides.
0 μm and the same, width 41.5 mm length 505 mm
And

Next, a positive electrode was prepared as follows.

The synthesis of the positive electrode active material (LiCoO 2) was performed as follows. Li / C for lithium carbonate and cobalt carbonate
o (molar ratio) = 1 and 900 in air.
C. for 5 hours. X-ray diffraction measurement of this material showed a good match with LiCoO _{2 of the} JCPDS card. Then, pulverize using an automatic mortar and LiCoO
Got _two . Using LiCoO ₂ thus obtained,
A positive electrode mixture was prepared by mixing 91% by weight of LiCoO _2, 6% by weight of graphite as a conductive material, and 3% by weight of polyvinylidene fluoride as a binder.
Dispersed in 2-pyrrolidone to obtain a positive electrode mixture slurry. Next, this positive electrode mixture slurry was applied to a belt-shaped 2 serving as a positive electrode current collector.
It was applied to both sides of a 0 μm aluminum foil, dried, and then compression-molded with a roller press to form a positive electrode. The band-like positive electrode had the same mixture thickness of 80 μm on both sides, and had a width of 39.5 mm and a length of 490 mm.

Next, these strip-shaped positive and negative electrodes and a separator made of a microporous polypropylene film having a thickness of 25 μm are sequentially laminated, and then spirally wound around a winding core having a rhombus shape. did. And the adhesive tape width 40
After fixing the end portion with mm, pressure was applied to deform the electrode to form an oval wound electrode body.

Next, the above-mentioned elliptical spirally wound electrode body was housed together with a spring plate in a nickel-plated iron rectangular battery can, and insulating plates were arranged on both upper and lower surfaces of the electrode body. And
One end of a nickel negative electrode lead was crimped to the electrode and the other end was welded to the battery can in order to collect current from the negative electrode. Also, in order to collect the current of the positive electrode, one end of an aluminum positive electrode lead was attached to the positive electrode, and the other end was laser-welded to the battery lid.

Next, 1 mol of LiPF ₆ was mixed into the battery can 5 from a liquid injection hole in a mixed solvent of 50% by volume of propylene carbonate and 50% by volume of diethyl carbonate.
Was dissolved from the electrolyte injection port. Then, the battery can and the battery lid are welded by laser, and the thickness is 8 m.
A square secondary battery having a height of 48 mm and a width of 34 mm was prepared.

At this time, the battery cover shown in FIG. 7 was used. 7, the same members as shown in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.

The battery cover shown in FIG. 7 is different from the battery cover shown in FIG. 1 in that a cleavage valve is not provided and the confirmation hole is not sealed with an insulating plate. That is, when the internal pressure of the battery increases, the disc spring 12 reverses and the current is interrupted, but when the internal pressure of the battery increases even after the current is interrupted, the sealing sheet 6 is torn and the confirmation hole is opened. The structure is such that the internal pressure of the battery is released from 17.

The first battery lid 1 and the second battery lid 2 were welded by resistance welding. The material of the disc spring is
A beryllium copper alloy having silver plating was used, and a second terminal having copper plated with silver was used. Further, the breaking pressure of the disc spring at this time was 5 kg / cm ² , and the breaking pressure of the cleavage valve was 20 kg / cm ² .

Experimental Example 2 A prismatic secondary battery was produced in the same manner as in Experimental Example 1, except that the confirmation hole was sealed with a rubber stopper made of butyl rubber.

EXPERIMENTAL EXAMPLE 3 Gold-plated springs, contacts and second terminals constituting a conduction path were prepared, and a prismatic secondary battery was produced in the same manner as in Experimental Example 2.

EXPERIMENTAL EXAMPLE 4 The concave portion of the first battery cover and the inside of the second battery cover were
Teflon insulation coating was performed and insulation treatment was performed. And
A prismatic secondary battery was fabricated in the same manner as in Experimental Example 2, using the components of Experimental Example 3 together.

Experimental Example 5 As shown in FIG. 1, the confirmation hole 17 was sealed with a front rear circular insulating plate 22 made of butyl rubber.
The insulating plate 22 was fixed and hermetically sealed. Also, the welding method of the first battery cover 1 and the second battery cover 2 was changed to laser welding.

The end-of-charge voltage was 4.20 V and the charging current was 300 m with respect to the prismatic secondary batteries of Experimental Examples 1 to 5.
The battery was charged for 10 hours under the condition A, and was fully charged.

Then, in order to confirm the effectiveness of the shut-off valve, a voltage of 20 V was applied at a charging current of 1.4 A to perform an overcharge test. Table 1 shows the results.

Next, in order to examine the environmental resistance, a battery was completely immersed in salt water, pulled up, and left for 7 days at room temperature to conduct a corrosion resistance test. Further, the pressure was reduced, and a test was made as to whether or not the saline solution had penetrated. Table 2 shows the results.

[0072]

[Table 1]

[0073]

[Table 2]

From the results shown in Tables 1 and 2, the corrosion resistance is improved in Experimental Examples 2 to 5 in which the confirmation holes 17 are sealed, as compared with Experimental Example 1 in which the confirmation holes 17 are not sealed. ,
It seems to have corrosion resistance that is practically no problem. In particular, Experimental Example 5 has excellent sealing properties even under reduced pressure,
In addition, because of the specification with improved insulating properties, a favorable result was obtained in which the internal resistance hardly changed even under a poor environment.

Next, using the same members as the prismatic secondary battery of Experimental Example 5, the prismatic secondary batteries shown in Experimental Examples 6 to 16 were examined in order to investigate appropriate breaking pressure and cleavage pressure. Produced.

Experimental Example 6 A prismatic secondary battery was produced in the same manner as in Experimental Example 5, except that the breaking pressure of the disc spring was set to 2 kg / cm ² .

Experimental Example 7 A prismatic secondary battery was produced in the same manner as in Experimental Example 5, except that the breaking pressure of the disc spring was 4 kg / cm ² .

Experimental Example 8 A prismatic secondary battery was manufactured in the same manner as in Experimental Example 5 except that the breaking pressure of the disc spring was set to 12 kg / cm ² .

Experimental Example 9 A prismatic secondary battery was manufactured in the same manner as in Experimental Example 5 except that the breaking pressure of the disc spring was set to 15 kg / cm ² .

Experimental Example 10 A prismatic secondary battery was produced in the same manner as in Experimental Example 5, except that the cleavage pressure of the cleavage valve was changed to 15 kg / cm ² .

Experimental Example 11 A prismatic secondary battery was manufactured in the same manner as in Experimental Example 5, except that the cleavage pressure of the cleavage valve was set to 30 kg / cm ² .

Experimental Example 12 A prismatic secondary battery was produced in the same manner as in Experimental Example 5, except that the cleavage pressure of the cleavage valve was 35 kg / cm ² .

Experimental Example 13 A prismatic secondary battery was produced in the same manner as in Experimental Example 5, except that the breaking pressure of the disc spring was set to 2 kg / cm ² .

Experimental Example 14 A prismatic secondary battery was manufactured in the same manner as in Experimental Example 5, except that the breaking pressure of the disc spring was set to 20 kg / cm ² .

Experimental Example 15 A prismatic secondary battery was produced in the same manner as in Experimental Example 5, except that the cleavage pressure of the cleavage valve was changed to 10 kg / cm ² .

Experimental Example 16 A prismatic secondary battery was produced in the same manner as in Experimental Example 5, except that the cleavage pressure of the cleavage valve was set at 40 kg / cm ² .

The prismatic secondary batteries produced in Experimental Examples 6 to 16 were charged with a charging end voltage of 4.20 V and a charging current of 30.
The battery was charged for 10 hours under the condition of 0 mA, and was fully charged.

Then, in order to confirm the effectiveness of the shut-off valve, a voltage of 20 V was applied with a charging current of 1.4 A, and an overcharge test was performed until the shut-off valve was broken. Table 3 shows the results.

Next, in order to confirm the effectiveness of the cleavage valve,
A combustion test with a gas burner was performed. The results are shown in Table 3.

[0090]

[Table 3]

From the results in Table 3, it can be seen that in Experimental Examples 6 to 12, the disc spring and the cleavage valve operated well.

On the other hand, the breaking pressure of the disc spring is 2 kg /
In Experimental Example 13 set to cm ² , the disc spring operated in normal use. In Experimental Example 14 in which the cut-off pressure of the disc spring was set to 20 kg / cm ² , the cut-off magnetism was slow, making it difficult to prevent the battery from being damaged quickly. Therefore, the breaking pressure is 3 to 15 kg / c.
m ² is preferred.

Further, the cleavage pressure of the cleavage valve is 8 kg / cm.
^In Experimental Example 15 set to ² , even if the current is interrupted by the disc spring, the cleavage valve operates due to an increase in the battery internal pressure, and liquid leakage occurs. Further, the cleavage pressure of the cleavage valve is 40 kg / c.
In Experimental Example 16 set to m ² , the operation of the cleavage valve is delayed, and the battery may swell and deform, and may burst from an unspecified portion. Therefore, the cleavage pressure is 12 to 35 kg / c.
m ² is preferred.

As described above, in consideration of durability and use at a high temperature (60 to 90 ° C.), the cutoff pressure is 4 to 10 kg /
cm ² and the cleavage pressure are more preferably 15 to 30 kg / cm ² .

[0095] Also, as in the Experimental Example 6 Experimental Example 12, the difference between these blocking pressure and rupturing pressure force, it is preferable that a 5 kg / cm ² or more, 10-20 kg / cm ² is more preferable.

[0096]

As is apparent from the above description, according to the present invention, when the internal pressure of the battery is increased due to overcharging or the like, the current is reliably cut off to prevent the internal pressure of the battery from rising. it can. If the internal pressure of the battery further increases even after the current is cut off, the internal pressure of the battery is released to the outside to prevent the battery from being rapidly damaged. Furthermore, according to the present invention, since the current interrupting means is sealed from the outside, a nonaqueous electrolyte secondary battery having excellent corrosion resistance can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view of a battery lid to which the present invention is applied.

FIG. 2 is a plan view of the battery cover.

FIG. 3 is a rear view of the battery cover.

FIG. 4 is a perspective view of a first battery cover of the battery cover.

FIG. 5 is a perspective view of a disc spring stored in a concave portion of the battery lid.

FIG. 6 is a schematic diagram showing a configuration of a prismatic secondary battery to which the battery cover is attached.

FIG. 7 is a perspective view of a battery lid used in Experimental Example 1.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 1st battery cover, 2nd battery cover, 3 opening, 4
Electrolyte injection port, 5 packing, 6 sealing sheet, 7
Placement hole, 8 first base, 9 first terminal, 10
Contact point, 11 Spring pressing, 12 Disc spring, 13 Second base, 14 Second terminal, 15 Conductive ring, 16, 1
7 Confirmation hole, 18 Cleavage valve, 19 Insulation case, 20
Pressure detection hole, 21 connection terminal, 22 insulating plate, 23 tab

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Ayaki Watanabe 1-1-1 Shimosugishita, Takakura, Hiwada-cho, Koriyama-shi, Fukushima Prefecture Inside Sony Energy Tech Co., Ltd. (72) Inventor Toshizo Kameishi Tennoji, Osaka, Osaka Inside Wako Electronics Co., Ltd. 8-22 Kadain-cho, Ward (72) Koji Kihara Inside Wako Electronics Co., Ltd. 8-22 Kandain-cho, Tennoji-ku, Osaka, Osaka

Claims (7)

[Claims] 1. A device comprising: a current interrupting means for interrupting a current when a battery internal pressure reaches a cutoff pressure; and a cleavage means for releasing a battery internal pressure when the battery internal pressure reaches a breaking pressure. In a non-aqueous electrolyte secondary battery having a pressure higher than the pressure, the current cut-off means is sealed from the outside by an insulating portion, and when the battery internal pressure exceeds the cut-off pressure, a cut-off valve constituting a part of a conduction path. However, the disconnection means disconnects the connection with the conduction path by reversing the curved shape, and the cleaving means is configured to be cleaved when the cleavage pressure is reached, thereby directly opening the internal pressure of the battery to the outside. Water electrolyte secondary battery. 2. An insulating section for sealing the current interrupting means from the outside, one end of which is substantially semi-circular, the other end of which is rectangular, and the insulating section on the substantially semi-circular side insulates a terminal. The prismatic non-aqueous electrolyte secondary battery according to claim 1, which also serves as: 3. The non-aqueous electrolyte secondary battery according to claim 2, wherein said cleaving means is provided on the substantially semicircular side of said insulating portion. 4. The rectangular non-aqueous electrolyte secondary battery according to claim 1, wherein the insulating portion that seals the current interruption to the outside is butyl rubber. 5. The current cutoff pressure is 3 to 15 kg / c.
m ^2, and the rupturing pressure force, prismatic nonaqueous electrolyte secondary battery according to claim 1, characterized in that the 12~35kg / cm ^2. 6. The rectangular non-aqueous electrolyte secondary battery according to claim 1, wherein the component constituting the conduction path has an outermost surface plated with gold or palladium. 7. The rectangular non-aqueous electrolyte secondary battery according to claim 1, wherein the battery lid has a recess below the terminal for accommodating the current interrupting means, and the inner wall of the recess is insulated.