JPH06196138A - Nonaqueous electrolyte battery - Google Patents

Abstract

PURPOSE:To prevent explosion at the time of increasing inner pressure due to excessive charging and short-circuit and the like through a process of preventing deformation of a core space part, in order to improve safety by arranging two pipes in the vicinity of both ends of the core space part of an electrode body, so that may come in contact with one another at the front end tilted part. CONSTITUTION:A coiled electrode body 4 which is wound up with a separator 3 interposed between a positive electrode 1 and a negative electrode 2, is stored in an outer packaging can 5. Two pipes 6a, 6b, the front end parts of which are tilted to the axial direction, are inserted from both end sides of the core space part 7 of the electrode body 4, and are arranged on the part 7 so that the front ends of the pipes 6a, 6b may come in contact with one another by a desired interval. The compressive strength of the pipes 6a, 6b is so strong that the pipes are not crushed even when gas is generated in the can 5 due to excess charging or short-circuit caused by erroneous operation, and when the gas pressure is applied in the direction where the electrodes 1, 2 and the separator 3 of the body 4, are mutually superimposed, and to respective pipes 6a, 6b, and the shape of the electrode body 4 can thus be retained. Since the gas is not enclosed in the electrode body 4 or the like, bursting caused by local increase in the pressure in the battery can be prevented, and safety can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-aqueous electrolyte battery having an explosion-proof mechanism.

[0002]

2. Description of the Related Art In recent years, there have been remarkable improvements in the performance and miniaturization of electronic devices such as video cameras and headphone stereos. The demand for higher density is also increasing. For this reason, non-aqueous electrolyte batteries using lithium metal, lithium alloys, or substances capable of occluding and releasing lithium such as carbonaceous materials as negative electrode materials have been actively developed.

However, with the increase in the density, the danger increases. For example, the non-aqueous electrolyte battery is supplied with a current longer than usual during charging to be in an overcharged state, or has a short circuit due to a large current flowing due to misuse during discharge or failure of equipment using the battery. When it becomes, the electrolytic solution is decomposed to generate gas, and the internal pressure of the battery rises. Further, if the overcharge or the short circuit continues, the battery temperature may suddenly rise due to the heat generated by the decomposition of the electrolytic solution, and the battery may burst.

Therefore, it is essential for practical use of the battery to prevent the internal pressure from rising and the bursting due to the heat generation. Therefore, a lithium secondary battery having an explosion-proof safety valve mechanism as shown in FIG. 5 is disclosed in Japanese Utility Model Publication No. 59-15398. That is, the spirally wound electrode body 43 produced by winding the positive electrode 40 and the negative electrode 41 through the separator 42 is housed in the outer can 44. The insulating plate 45 is interposed between the electrode body 43 and the outer can 44, and electrically insulates the electrode body 43 and the outer can 44 from each other. The non-aqueous electrolytic solution is contained in the outer can 44. The sealing body 46 is attached to the opening of the outer can 44 by caulking and fixing via an insulating material 47 to seal the outer can 44. The sealing body 46 has a flexible thin plate 50, which is a constituent member of a safety valve mechanism described later, interposed between a terminal plate 48 and a hat-shaped terminal plate 49, and the terminal plate 4
8 has a structure in which the cap-shaped terminal plate 49 is bent and integrated with the upper peripheral portion of the terminal plate 49. One end of the positive electrode lead 51 is connected to the positive electrode 40, and the other end is connected to the lower end of the terminal plate 48.

The safety valve mechanism 52 is formed by cutting a circular hole 53 provided in a central portion of the terminal plate 48 and two sides of a triangle in the vicinity of the center of the cap-shaped terminal plate 49, and cutting the two sides. And a blade 54 formed by bending the triangular portion downward to face the hole 53, and the hat-shaped terminal plate 4 formed by the blade 54.
9 has a triangular hole 55 and the terminal plates 48, 4
The flexible thin plate 50 is interposed between the flexible thin plates 50. The flexible thin plate 50 is composed of a composite member of a metal layer and a synthetic resin layer.

In the secondary battery having such a structure, the gas generated in the outer can 44 due to overcharge, short circuit, etc.
The electrode body 43 moves to the opening of the outer can 44 along the surface of the separator 42 or flows to the bottom of the outer can 44 along the surface of the separator 42.
The flexible thin plate 50 is pressed through the hole 53 of the terminal plate 48 by moving through the core space 56 at the center of the package toward the opening of the outer can 44. As a result, the flexible thin plate 50 swells due to the pressure, and is broken by coming into contact with the blade 54 protruding downward from the hat-shaped terminal plate 49. Therefore, the gas filled in the outer can 44 is discharged through the breakage portion of the thin plate 50 and the triangular hole 55 of the terminal plate 49 to prevent the secondary battery from bursting.

By the way, in the secondary battery, in order to increase the capacity and energy, it is necessary to increase the facing area between the positive electrode 40 and the negative electrode 41. However, in order to increase the specific surface area of the positive electrode 40 and the negative electrode 41 in a battery having a limited size, it is necessary to reduce the thickness of these electrode plates, and accordingly, the electrode plates are formed. The shape retention of the electrode body 43 thus formed is lowered. As a result, when gas is generated in the outer can 44 due to the above-mentioned overcharge or the like, the gas pressure changes the positive electrode 4 of the electrode body 43.
0, the negative electrode 41, and the separator 42 are added in the stacking direction, so that the core space portion 56 is collapsed and the gas passage is blocked. Therefore, the diffused gas is trapped near the bottom of the electrode body 43, and the internal pressure of the battery locally rises, so that the electrode body 43 itself is pushed up toward the sealing body 46 and the outer can 44 bursts. There was a problem.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the conventional problems, and can prevent the deformation of the core space of the electrode body and can prevent the internal pressure from rising due to overcharge or short circuit. It is intended to provide a highly safe non-aqueous electrolyte battery capable of preventing the rupture of the electrolyte.

[0009]

According to the present invention, there is provided an electrode body housed in an outer can, which is spirally wound between a positive electrode and a negative electrode with a separator interposed therebetween, and a non-container housed in the outer can. In a non-aqueous electrolyte battery provided with a water electrolyte and a safety valve mechanism, two pipes are arranged near both ends of a winding core space of the electrode body so that their tips are in contact with each other, and In the non-aqueous electrolyte battery, the tip of the pipe has a shape inclined with respect to the axial direction. A non-aqueous electrolyte battery according to the present invention will be described with reference to FIGS. 1 and 2.

A spirally wound electrode body 4 wound between a positive electrode 1 and a negative electrode 2 with a separator 3 in between is housed in an outer can 5. 2 whose tip has a shape inclined with respect to the axial direction
The pipes 6a and 6b are inserted from both ends of the core space portion 7 of the electrode body 4 as shown in FIG. 2, for example, and the core spaces are arranged such that the tips of the pipes 6a and 6b contact each other. It is arranged in the section 7. The insulating plate 8 is interposed between the electrode body 4 and the outer can 5, and electrically insulates the electrode body 4 and the outer can 5 from each other. The non-aqueous electrolyte is
It is housed in the outer can 5. The sealing body 9 is attached to the opening of the outer can 5 via an insulating material 10 by caulking and fixing, and seals the outer can 5. The sealing body 9
Is a flexible thin plate 13, which is a component of a safety valve mechanism described later, interposed between the terminal plate 11 and the hat-shaped terminal plate 12, and the terminal plate 11 is placed on the upper periphery of the hat-shaped terminal plate 12. It has a structure that is folded and integrated. The positive electrode lead 14 has one end connected to the positive electrode 1 and the other end connected to the lower end of the terminal plate 11.

The safety valve mechanism 15 is formed by a circular hole 16 provided in the central portion of the terminal plate 11 and two triangular sides cut near the center of the cap-shaped terminal plate 12 and by the cut. A blade 17 facing the hole 16 formed by bending a triangular portion downward, and the hat-shaped terminal plate 1 formed by the blade 17.
2 has a triangular hole 18 and the terminal plates 11 and 1
The flexible thin plate 13 is interposed between the two. The flexible thin plate 13 is composed of a composite member of a metal layer and a synthetic resin layer.

Each of the pipes 6a and 6b has an outer diameter of 4 mm and an inner diameter of 3 mm in order to prevent deformation due to the pressure of the gas generated in the outer can 5 due to overcharge, short circuit or the like.
It is desirable that the pipe is made of a material having a compressive strength of 10 kgf or more. Furthermore, each of the pipes 6
It is desirable that a and 6b are formed of a material that is not deformed by the heat generated when the internal pressure rises and does not react with the electrolytic solution or the like. Examples of such a material include metals such as stainless steel, iron and nickel, and heat resistant plastics such as polyimide.

Each of the pipes 6a, 6b preferably has a shape in which the tip portion is inclined at an angle within the range of 30 ° to 60 ° with respect to the axial direction. If the angle is less than 30 °, the tips of the pipes 6a and 6b become thin and fragile, so that the pipes 6a and 6b can be connected to the core space portion 7.
If it is inserted and arranged from both ends, the tip may be deformed. On the other hand, when the angle exceeds 60 °, when the pipes 6a and 6b are arranged in the core space portion 7 by the method described above, the inner circumferences of the pipes 6a and 6b and the core space portion 7 are increased. Since the degree of friction between the surface and the separator 3 increases, the separator 3 may be damaged. However, each of the pipes 6a and 6b may have a shape in which the tip portions are inclined at the same angle with each other or a shape in which the tip portions are inclined at different angles within the above angle range. Particularly, from the viewpoint of improving the strength of the winding core space 7, the pipes 6a and 6b each having a shape in which the tips are inclined at the same angle are brought into contact with each other at their inclined surfaces to be integrated. It is desirable to arrange the material in the core space 7.

The wall thickness of each of the pipes 6a and 6b made of the material having the compressive strength is preferably in the range of 0.2 mm to 1.0 mm. If the wall thickness is less than 0.2 mm, the strength of each of the pipes 6a and 6b decreases,
When the pressure of the gas is applied to the pipes 6a and 6b, the pipes 6a and 6b may be crushed and the electrode body 4 may be deformed. On the other hand, if the wall thickness exceeds 1.0 mm, the battery capacity may decrease.

The positive electrode 1 has a structure in which a chalcogen compound such as a lithium manganese composite oxide or a lithium cobalt composite oxide, an organic binder and a conductive material are mixed and formed into a sheet, which is pressed onto a current collector. There is. As the organic binder, for example, polytetrafluoroethylene or the like can be used. As the conductive material, for example, acetylene black or graphite can be used.

The current collector has, for example, a thickness of 10 μm to increase the specific surface area of the positive electrode 1 in a battery having a limited size to increase the capacity and energy of the battery. It is desirable to use a thin metal plate of 100 μm. As the metal plate, for example, aluminum foil, stainless steel foil, nickel foil or the like can be used. The negative electrode 2 has a structure in which a mixture composed of a carbonaceous substance that absorbs and releases lithium ions and an organic binder is applied to and covered by a current collector. As the organic binder, for example, ethylene propylene copolymer or the like can be used.

The current collector has, for example, a thickness of 10 μm to increase the specific surface area of the negative electrode 2 in a battery having a limited size so as to increase the capacity and energy of the battery. It is desirable to use a thin metal plate of 100 μm. As the metal plate, for example, copper foil, stainless steel foil, nickel foil, or the like can be used. As the negative electrode 2, a negative electrode made of a metallic lithium sheet is also used. As the separator 3, for example, a polypropylene porous film, a polyethylene microporous film, or the like can be used.

The non-aqueous electrolyte is, for example, lithium hexafluorophosphate (LiPF ₆ ) or lithium borofluoride (LiBF).
₄ ), an electrolyte such as lithium perchlorate (LiClO ₄ ) or the like is dissolved in, for example, a mixed solvent of propylene carbonate and dimethoxyethane or a mixed solvent of propylene carbonate and γ-butyl lactone.

[0019]

According to the present invention, the two pipes 6a and 6b are provided near both ends of the core space 7 of the electrode body 4 which is spirally wound with the separator 3 interposed between the positive electrode 1 and the negative electrode 2. Are arranged such that their tips are in contact with each other, and the pipes 6a, 6 are
Since the tip of b has a shape inclined with respect to the axial direction, gas is generated in the outer can 5 due to short circuit due to overcharge or misuse, and the gas pressure is the positive electrode of the electrode body 4. 1, when the negative electrode 2 and the separator 3 are overlapped with each other and when applied to the pipes 6a and 6b, the pipes 6a and 6b have high compressive strength.
The a and 6b are not crushed and the electrode body 4 can maintain its spiral shape. Therefore, the gas can quickly pass through the pipes 6a and 6b without being confined in the electrode body 4 or the bottom of the outer can 5, and move to the safety valve mechanism 15 side. As a result, it is possible to prevent rupture caused by the local increase in the battery internal pressure.

Further, when the pipes 6a and 6b are inserted and arranged from both ends of the core space 7, the breakage of the separator 3 on the inner peripheral surface of the core space 7 can be suppressed. It is possible. That is, when inserting a pipe into the winding core space, the degree of friction between the pipe and the separator near the insertion opening of the winding space is determined by the length of the pipe and the contact between the pipe and the separator. It depends on the area. Therefore, when one pipe is inserted from one end side of the winding core space, the degree of friction increases, and the separator is easily damaged. On the other hand, when two pipes are inserted from both ends of the winding core space, the degree of friction is about half that when one pipe is inserted. Further, when the tip portions of the two pipes are inclined with respect to the axial direction as in the present invention, the area in which the pipes and the separator contact each other is reduced, so that the friction degree is further reduced. To be done. As a result, when inserting and arranging the two pipes having the tips of the above-described shapes near both ends of the winding core space, it is possible to suppress damage to the separator on the inner peripheral surface of the winding space. Will be possible.

[0021]

Embodiments of the present invention will be described below with reference to the drawings. Example 1

L which is a composite oxide of lithium and cobalt
A paste was prepared by adding a conductive material and a binder to iCoO ₂ . The paste was applied on an aluminum substrate having a thickness of 20 μm and then dried to prepare a sheet-shaped positive electrode plate. Then, the thickness of the positive electrode and the negative electrode is 100 μm.
A polyethylene microporous film as a separator was interposed between the metallic lithium sheet of m and the metal lithium sheet, and the spirally wound electrode body was produced. Continuing with FIG.
As shown in FIG. 2, 2 from both ends of the core space portion of the electrode body.
Two stainless steel pipes were inserted, and the two pipes were arranged near both ends of the core space so that the tips of the two pipes contact each other. The two pipes have a wall thickness of 0.
The one having a shape having a tip of 5 mm and inclined by 30 ° with respect to the axial direction was used.

Then, the electrode body is housed in a stainless steel outer can having an outer diameter of 17 mm and a height of 50 mm, and after injecting an electrolytic solution, the electrode body is caulked and sealed by using a sealing body.
The cylindrical non-aqueous electrolyte battery shown in FIG. 1 and having a capacity of 900 mAh was assembled. The electrolytic solution used was a mixed solvent of propylene carbonate and dimethoxyethane in which 1 mol of a solute of lithium phosphorus fluoride (LiPF ₆ ) was dissolved. Example 2

Non-aqueous electrolysis similar to that of Example 1 was performed by using the same spirally wound electrode body as that of Example 1 except that two pipes each having a tip end inclined by 60 ° with respect to the axial direction were used. A liquid battery was assembled. Example 3

Non-aqueous electrolysis similar to that of Example 1 was performed by using the same spirally wound electrode body as that of Example 1 except that two pipes each having a tip end inclined by 20 ° with respect to the axial direction were used. A liquid battery was assembled. Example 4

The same non-aqueous electrolysis as in Example 1 was performed by using the same spirally wound electrode body as in Example 1 except that two pipes each having a tip portion inclined by 70 ° with respect to the axial direction were used. A liquid battery was assembled. Comparative Example 1 A spirally wound electrode body similar to that of Example 1 was used, except that no pipe was arranged in the core space, and Example 1 was used.
A similar non-aqueous electrolyte battery was assembled.

The produced Examples 1 to 4 and Comparative Example 1
Prepare 20 batteries each and supply 2A current to 24
Overflowing was carried out for a period of time, and an overcharge test was carried out to check the number of batteries that had burst. The results are shown in Table 1 below.

As is apparent from Table 1, in the batteries (Examples 1 to 4) provided with the electrode body in which the two pipes having the above-mentioned tip portions are arranged in the core space portion, the bursting occurs. It can be seen that there is no battery in which the occurrence of the phenomenon occurs, and it is possible to prevent the explosion. On the other hand, in the battery (Comparative Example 1) provided with the electrode body in which the pipe was not arranged in the winding core space, it was found that the number of the batteries that ruptured was extremely large, nine.

Next, for each of the 100 batteries of Examples 1 to 4, when the two pipes were inserted from both ends of the core space, the separators on the inner peripheral surface of the core space were The number of batteries that were damaged and caused a short circuit was examined. The results are shown in Table 2 below.

The battery (Example 3) provided with an electrode body in which two pipes each having a tip inclined by 20 ° with respect to the axial direction is arranged in the core space portion (third embodiment) has a thin tip. The tips were slightly bent depending on the insertion method used when inserting the two pipes into the core space. Example 5

L which is a composite oxide of lithium and cobalt
A paste was prepared by adding a conductive material and a binder to iCoO ₂ . The paste was applied on an aluminum substrate having a thickness of 20 μm and then dried to prepare a sheet-shaped positive electrode plate. Subsequently, a binder was added to a carbonaceous material supporting lithium or an alkali metal mainly containing lithium to prepare a paste. The paste has a thickness of 20 μm
After being applied to the copper substrate of No. 3, it was dried to prepare a sheet-shaped negative electrode plate.

Then, a polypropylene porous film as a separator was interposed between the positive electrode and the negative electrode and wound to prepare a spirally wound electrode body. Then, as shown in FIG. 2 described above, two stainless steel pipes are inserted from both ends of the core space of the electrode body, and the two pipes are inserted near both ends of the core space. The tips were placed in contact with each other. As the two pipes,
The wall thickness was 0.5 mm, and the tip portion had a shape inclined by 30 ° with respect to the axial direction.

Then, the electrode body is housed in a stainless steel outer can having an outer diameter of 18 mm and a height of 83 mm, and after injecting an electrolytic solution, the electrode body is caulked and sealed by using a sealing body.
The cylindrical non-aqueous electrolyte battery shown in FIG. 1 and having a capacity of 1300 mAh was assembled. The electrolytic solution used was prepared by dissolving lithium borofluoride (LiBF ₄ ) as an electrolyte in a mixed solvent (volume ratio of 50:50) of propylene carbonate and γ-butyl lactone.

A current of 2 A was applied to the 20 prepared batteries for 24 hours, and an overcharge test was carried out to examine the number of the batteries that had ruptured. As a result, none of the batteries ruptured. When 100 pipes of Example 5 were arranged by inserting the two pipes from both ends of the core space part, the separator on the inner peripheral surface of the core space part was damaged and a short circuit occurred. When the batteries were examined, none of the batteries caused a short circuit. Therefore, the battery of Example 5 is also used in Example 1.
The same effect as was obtained.

Although the non-aqueous electrolyte batteries having the safety valve mechanism shown in FIG. 1 have been described in the first to fifth embodiments,
The present invention is not limited to this. For example, it can be similarly applied to a non-aqueous electrolyte battery having a safety valve mechanism shown in FIGS. 3 and 4 described below.

The outer can 21 which also serves as the negative electrode terminal accommodates the electrode body in which the above-mentioned two pipes are arranged in the core space so that the tips thereof contact each other. The sealing body 22 having a hole in the center is attached to the outer can 21 in an airtight manner. Both ends of the positive electrode pin terminal 23 have the sealing body 22.
The outer can 21 and the sealing body 22 are attached to the central hole of the sealing body 22 by a hermetic seal via a glass insulating material 24 so as to project from the upper and lower surfaces.
I am trying to insulate it from.

The safety valve mechanism 25 is attached to the hole 26 opened in the sealing body 22 and the outer surface of the sealing body 22, and the valve membrane is formed at the bottom by the groove 27 provided at a position corresponding to the hole 26. And a thin film 28. The holes 26 are, for example, three arc-shaped holes formed concentrically with the center of the sealing body 22. The groove 2
The reference numeral 7 includes, for example, a circular groove 29 provided at a position corresponding to the hole 26 and a linear groove 30 intersecting with the circular groove 29 and extending radially from the center of the sealing body. The thin film 28 has, for example, a ring shape.

In the non-aqueous electrolyte battery having such a structure, the gas generated in the outer can 21 due to overcharge, short circuit or the like passes through the two pipes to the safety valve mechanism 25 side. After moving, pressure is applied to the valve membrane portion of the thin film 28 through the arc-shaped hole 26 formed in the sealing body 22, and the valve membrane is broken. Therefore, the gas escapes to the outside from the hole 26 and the break point of the valve membrane,
It is possible to prevent the battery from bursting as in the first to fifth embodiments. Although the first to fifth embodiments are described as being applied to the cylindrical non-aqueous electrolyte battery, they can be similarly applied to the rectangular non-aqueous electrolyte battery. Example 1
In Example 5, the description was made by applying it to the secondary battery, but it can be similarly applied to the primary battery.

[0039]

As described above in detail, according to the present invention, it is possible to prevent the core space of the electrode body from being deformed, and prevent the bursting when the internal pressure rises due to overcharge or short circuit. It is possible to provide a highly safe non-aqueous electrolyte battery.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a non-aqueous electrolyte battery of the present invention.

2 is a cross-sectional view showing a state where a pipe is inserted into an electrode body of the battery shown in FIG.

FIG. 3 is a perspective view showing another non-aqueous electrolyte battery of the present invention.

FIG. 4 is an exploded perspective view showing a main part of the battery of FIG.

FIG. 5 is a cross-sectional view showing a conventional non-aqueous electrolyte battery.

[Explanation of symbols]

1 ... Positive electrode, 2 ... Negative electrode, 3 ... Separator, 4 ... Electrode body, 5
... exterior cans, 6a, 6b ... pipes, 7 ... core space part, 15
… Safety valve mechanism.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Soichi Hanafusa 3-4-10 Minami-Shinagawa, Shinagawa-ku, Tokyo Within Toshiba Battery Co., Ltd. (72) Eijiro Matsuzaka 1-3-1, Yokou, Kawasaki-ku, Kawasaki-shi, Kanagawa No. Asahi Kasei Kogyo Co., Ltd. (72) Inventor Katsuhiko Inoue 1-3-1 Yokou, Kawasaki-ku, Kawasaki-shi, Kanagawa Asahi Kasei Kogyo Co., Ltd.

Claims (1)

[Claims] 1. An electrode body housed in an outer can, which is spirally wound between a positive electrode and a negative electrode with a separator interposed therebetween, a non-aqueous electrolyte contained in the outer can, and a safety valve mechanism. In a non-aqueous electrolyte battery provided with, two pipes are arranged in the vicinity of both ends of the winding core space portion of the electrode body so that the tips contact each other, and the tip portions of the two pipes are arranged in the axial direction. A non-aqueous electrolyte battery having a shape inclined with respect to the non-aqueous electrolyte battery.