JPH10188933A - Organic electrolyte battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the irregularity of breakage pressure on a valve disc for enhancing safety and ensure leakage prevention of electrolyte. SOLUTION: A sealer for a battery consists of a dish shaped sealing plate 8c, a valve disc 8b, a ring reinforcing plate 8f, a PTC element plate 8d and a cap. An area except a peripheral caulked area on the dish sealing plate 8c is flat to be adhered to the whole area excluding a valve disc 8b and a valve opening 8a, so that extra elongation and deformation of the valve disc 8b excluding a pressurized part is eliminated to reduce the irregularity of breakage pressure on the valve disc 8b. As an adhesion area between the valve disc 8b and the disc sealing plate 8c is increased, the leakage of electrolyte is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic electrolyte battery including an organic electrolyte-based battery power generation element, and more particularly to an organic electrolyte battery with improved safety and reliability of a sealing portion. .

[0002]

2. Description of the Related Art In recent years, as a non-aqueous electrolyte battery, an organic electrolyte battery using a light metal such as lithium or sodium as a negative electrode has attracted attention as a battery having high voltage, high energy density and long-term reliability. For example, a lithium primary battery using manganese dioxide (MnO ₂ ), fluorocarbon (CF ₂ ) _n, or the like as a positive electrode active material is frequently used as a backup battery for cameras, calculators, watches, clocks, and memories.

On the other hand, secondary batteries incorporated in various equipment systems such as portable telephones and portable image pickup devices and used as operating power sources are also reduced in size and weight, such as portable telephones and portable image pickup devices. Accordingly, a secondary battery having a high energy density is required as a power source.

In response to this demand, development of an organic electrolyte secondary battery using lithium or the like as a negative electrode has been advanced. In this type of organic electrolyte secondary battery, (a) a substance or metal lithium capable of occluding and releasing lithium ions as the negative electrode, and (b) propylene carbonate, ethylene carbonate, and the like as the lithium ion conductive electrolyte. In an organic solvent such as 1,2-dimethoxyethane, γ-butyllactone, and tetrahydrofuran, for example, LiClO ₄ , LiB
An organic electrolyte (non-aqueous electrolyte) obtained by dissolving a lithium salt such as F ₄ , LiAsF ₆ , or LiPF ₆ , or a lithium ion conductive solid electrolyte; and (c) a vanadium oxide or cobalt mainly used as a positive electrode active material. Compounds involved in the topochemical reaction with lithium, such as oxides and manganese oxides, are used.

By the way, organic electrolyte batteries are required to have stable hermeticity and airtightness over a long period of time, and a sealing structure with a high degree of hermeticity is being developed. However, the high degree of sealing of the sealing structure raises a problem in terms of safety against an internal short-circuit or an external short-circuit of the battery, or overdischarge. That is, when gas is generated inside the battery due to a short circuit or overdischarge, the internal pressure of the battery increases due to the airtightness, and there is a possibility that the outer can or the like may be broken or burst.

[0006] In order to solve the above-mentioned safety problem, a PTC element is disposed in the conductive circuit of the battery sealing portion in order to cut off the current at the time of short circuit or overdischarge and prevent the battery internal pressure from rising. It is known that a thin valve body is provided at the battery sealing portion to prevent the battery from being damaged and explosion or damage due to release of gas in the battery (see Japanese Utility Model Application Laid-Open No. 2-05).
0957).

FIG. 3 shows an example of a conventional countermeasure. In the figure, reference numeral 1 denotes an outer can also serving as a negative electrode terminal in which an organic electrolyte-based battery power generation element 2 is provided. Reference numeral 3 denotes a sealing body. The opening of the outer can 1 is hermetically sealed by caulking via an insulating packing material 4. And also serves as a positive electrode terminal. This sealing body 3 is (1) a flat peripheral dish-shaped sealing plate 3d in which peripheral parts of a valve body 3b and a ring-shaped reinforcing plate 3c corresponding to a valve opening 3a provided at the center are fixed by caulking.
(2) an annular PTC element plate 3e (a portion corresponding to the valve element 3b is cut out) disposed on a flat peripheral surface of the dish-shaped sealing plate 3d; and (3) a surface of the PTC element plate 3e. And a cap 3f in which a region corresponding to the valve body 3b of the dish-shaped sealing plate 3d is projected, and the cap 3f is provided with a cutting blade 3f 'and a gas at the projected portion. A lead hole 3f ″ is provided. Reference numeral 5 denotes a lead piece that electrically connects the sealing body 3 and the positive electrode side of the battery power generation element 2.

[0008]

As described above, in the conventional example described above, the current in the event of a short circuit or overdischarge is cut off to prevent the internal pressure of the battery from rising, while the upper pressurized gas in the battery is discharged to explode.・ Measures have been taken to avoid damage, but the following problems still exist in such cases.

For example, when the internal pressure of the battery rises and the valve body expands outwardly of the battery container, in the case of the configuration shown in FIG. 3, a ring is attached to the bonding portion 3g between the sealing plate 3a and the valve body 3b. Since the central vent hole 3a 'of the reinforcing plate has a small diameter, not only the valve body corresponding to the vent hole but also the bonding portion 3
Since the portion inside g is expanded along the gas vent hole while being stretched, the pressure at which the valve body 3b breaks varies.

The valve body made of a single member or a composite member such as a synthetic rubber, a synthetic resin, a metal thin plate or the like is fixed by adhesive caulking only to the inner peripheral portion 3g excluding a portion protruding toward the power generation element of the dish-shaped sealing plate. In addition, the valve body is extremely thin, so it is easy for center displacement to occur when the valve body is incorporated into the dish-shaped sealing plate during the manufacturing process.If center displacement occurs, the adhesion is insufficient and the sealing performance is reduced. , For example, 60 ° C
There has been a problem that liquid leakage occurs during storage at a high temperature or for a long period of time.

The present invention has been made in view of such circumstances, and its object is to reduce the cost, while improving the safety by reducing the variation in the breakage pressure of the valve element. An object of the present invention is to provide a highly reliable organic electrolyte battery that can reliably prevent leakage of an electrolyte.

[0012]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention is an organic electrolyte battery having an improved sealing body. That is, the present invention provides an outer can that contains an organic electrolyte-based battery power generation element and also serves as a negative electrode terminal, and a positive electrode hermetically sealed by caulking and fixing the opening of the outer can through an insulating packing material. In an organic electrolyte battery having a sealing body also serving as a terminal, the sealing body has a valve port in the center and a valve body is fixed via a ring-shaped reinforcing plate by caulking a peripheral rising portion inward. A dish-shaped sealing plate, a ring-shaped positive temperature coefficient resistance element (PTC element) plate laminated on a peripheral caulking portion of the dish-shaped sealing plate, and a laminated body disposed on the PTC element plate. A corresponding region protruding and a cap provided with a vent hole in the protruding portion, wherein the plate-shaped sealing plate has a flat bottom, so that the valve element has a portion excluding the valve port. In the dish-shaped sealing plate Characterized in that it is. In the above, the valve opening of the sealing plate,
The central vent hole of the ring-shaped reinforcing plate preferably has substantially the same diameter.

In the present invention, the positive electrode may be, for example, a material in which an active material such as manganese dioxide or fluorocarbon is applied to the surface of an expanded metal or punched metal plate as a positive electrode current collector. Can be Further, examples of the negative electrode include a metal lithium foil and a metal sodium foil.

Examples of the organic electrolyte usable in the present invention include ethylene carbonate, propylene carbonate, butylene carbonate, γ-butyrolactone, sulfolane, acetonitrile, 1,2-dimethoxyethane, 1,3-dimethoxypropane, dimethyl ether, and the like. An organic solvent (non-aqueous solvent) comprising at least one selected from the group consisting of tetrahydrofuran, 2-methyltetrahydrofuran, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, and methyl propionate is added with lithium perchlorate (LiClO ₄ ), Lithium hexafluorophosphate (LiPF ₆ ), lithium borofluoride (LiBF ₄ ),
An organic electrolyte in which a lithium salt (electrolyte) such as lithium arsenic hexafluoride (LiAsF ₆ ) or lithium trifluoromethanesulfonate (LiCF ₃ SO ₃ ) is dissolved in about 0.3 to 1.5 mol / l is generally mentioned. Can be Instead of the non-aqueous electrolyte, a solid electrolyte having ion conductivity, for example, a polymer solid electrolyte in which a lithium salt is combined with a polymer compound can be used.

Further, as a separator for insulating and separating the negative electrode and the positive electrode, for example, a nonwoven fabric or a porous film of a polyolefin resin such as polyethylene or polypropylene can be used.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. (Embodiment 1) FIG. 1 is a sectional view of a main part of an organic electrolyte battery according to an embodiment of the present invention. In the figure, reference numeral 6 denotes an iron outer can also serving as a negative electrode terminal in which an organic electrolyte-based battery power generating element 7 is enclosed, and 8 denotes an airtight seal of the opening of the outer can 6 via a synthetic resin insulating packing material 9. It is a sealing body which also functions as a positive electrode terminal for sealing. Reference numeral 10 denotes a sealing body 8 and a battery power generation element 7.
Are lead pieces for electrically connecting the negative electrode side of the lead wire.

In the above configuration, the battery power generating element 7 comprises a negative electrode material made of metallic lithium foil, a positive electrode material made by coating manganese dioxide on an expanded metal surface, and a separator made of a porous polypropylene resin film. Is wound on a wound body (wrapped body), a mixed solvent of propylene carbonate and 1,2-dimethoxyethane is used as an electrolyte, and lithium trifluoromethanesulfonate (LiCF ₃ S) is used as an electrolyte.
It is constituted by impregnating an organic electrolyte solution in which O ₃ is dissolved.

The sealing body 8 comprises a dish-shaped sealing plate 8c and an annular P
It is composed of a TC element plate 8d and a cap 8e. The dish-shaped sealing plate 8c has a valve port 8a in the center of the bottom flat surface, and the valve port 8a has an inner side (cap side) of the dish-shaped sealing plate.
The valve body 8b is installed so as to close it, and the peripheral rising edge of the dish-shaped sealing plate 8c is caulked inward to strengthen the reinforcing plate 8f.
The valve element 8b is fixed through the valve body 8b. The annular PTC element plate 8d has a cut-out portion corresponding to the valve element 8b, and is arranged on the peripheral caulking portion of the dish-shaped sealing plate 8c. The cap 8e has a region corresponding to the valve element protruding, and is provided with a gas vent hole 8e '. The cap 8e has a flat peripheral portion surrounding the PTC element plate 8d.
Are stacked on top of each other.

The valve body 8b is formed by laminating, for example, an aluminum foil and a modified polypropylene resin film or a polyethylene resin film. The periphery of the valve body 8b is not only fixed by caulking but also thermally fused to the surface of the dish-shaped sealing plate 8c. Or it is stuck with an adhesive.

With respect to the organic electrolyte battery of the present embodiment, pressure was applied by air from only the power generation element side using only the sealing portion, and the breakage pressure of the valve body was examined. Furthermore, the organic electrolyte battery of the present example was subjected to a storage test (1000 tests) at 60 ° C. for 120 days, and the presence or absence of liquid leakage was investigated.

On the other hand, as a comparative example, with respect to the conventional organic electrolyte battery whose main part configuration is shown in FIG. 3, an examination was also made of the damage pressure of the valve body and a storage test at 60 ° C. for 120 days. Table 1 shows the results.

[0022]

[Table 1]

As is clear from the above test, in the case of the organic electrolyte battery of this embodiment, the variation (standard deviation) of the valve breakage pressure is small, and the leakage of the electrolyte during the storage test at 60.degree. I was not able to admit. On the other hand, in the organic electrolyte battery of the comparative example, the variation in the breakage pressure of the valve body was large, and the leakage of the electrolyte during the storage test at 60 ° C. was confirmed. As a result of disassembling and examining the sealing body of the battery in which the electrolyte leaked, the valve body having a small adhesive area to the dish-shaped sealing plate was peeled off due to the center displacement of the valve body when the sealing body was assembled, and the airtightness was reduced. It was confirmed that it had been damaged.

The reason why the variation of the valve body breaking pressure in the present invention is reduced is that, as is apparent from FIG. 1, the sealing body according to the present invention has a plate-shaped sealing plate because the bottom of the plate-shaped sealing plate is flat. This is because it is well held at the bottom of the sealing plate, so that there is no large difference between the diameter of the pressure receiving portion of the valve body and the diameter of the gas vent hole of the ring-shaped reinforcing plate. In other words, when the valve body expands to the outside of the battery container when the internal pressure of the battery rises, the parts other than the pressure receiving part of the valve body are adhered to the dish-shaped sealing plate and sandwiched by the ring-shaped reinforcing plate. This is because extra elongation and deformation of the battery are eliminated, and the internal pressure of the battery concentrates on the pressure receiving portion. Therefore, it is particularly effective when the diameter of the pressure receiving portion of the valve body and the diameter of the gas vent hole of the ring-shaped reinforcing plate are the same.

(Embodiment 2) FIG. 2 is a sectional view of a main part of an organic electrolyte battery according to another embodiment of the present invention. As shown in FIG. 2, in order to prevent the valve body from being damaged by burrs generated when processing the inner hole of the sealing plate and the ring-shaped reinforcing plate, the inner hole is opposed to the valve body. Burring is applied in the direction.

In the organic electrolyte battery according to the present invention, since the valve body is entirely adhered to the flat bottom surface of the dish-shaped sealing plate except for the valve port, the variation in the breakage pressure of the valve body is reduced, and the safety is improved. Performance can be improved. In addition, since the bonding area between the dish-shaped sealing plate and the valve body increases, the necessary bonding area can be ensured even when the center of the valve body is misaligned during manufacturing, and the airtightness is reliably maintained to prevent leakage of the electrolyte. Can be prevented. Therefore, a highly reliable organic electrolyte battery can be provided.

Further, when the valve body is incorporated into the dish-shaped sealing plate, the valve body is punched out circularly with a hoop-shaped sheet material. In order to improve the valve body punching yield at this time, the valve body shape is made polygonal. In this case, a necessary bonding margin area can be secured. Therefore, cost reduction can be achieved. Note that the present invention is not limited to these embodiments, and various modifications can be made without departing from the spirit of the invention.

The same operation and effect can be obtained by adopting a configuration in which the components of the positive electrode and the negative electrode and the components of the separator are changed to known positive electrodes, negative electrodes, and separators.

[0029]

As described above, in the organic electrolyte battery of the present invention, since the valve body does not grow excessively when the internal pressure of the battery rises, the variation in the breakage pressure of the valve body is reduced and the safety is improved. I do. Further, since a sufficient area for bonding the valve body to the dish-shaped sealing plate can be ensured, excellent airtightness is exhibited in a normal use state, and there is no possibility of causing a problem such as leakage of the electrolyte solution, and reliability is improved. Therefore, the organic electrolyte battery of the present invention is particularly suitable as a power source for portable electronic devices.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of an organic electrolyte battery according to an embodiment of the present invention.

FIG. 2 is a sectional view of a main part of an organic electrolyte battery according to another embodiment of the present invention.

FIG. 3 is a cross-sectional view of a main part of a conventional organic electrolyte battery.

[Explanation of symbols]

1, 6: outer can, 2, 7: battery power generation element, 3, 8: sealing body, 4, 9: insulating packing, 3a, 8a, 8a ',
8a "... Valve port, 3b, 8b ... valve element, 3d, 8c, 8c '
... Dish-shaped sealing plate, 3e, 8d ... PTC element plate, 3f, 8e
... Cap, 3c, 8f ... Ring-shaped reinforcing plate, 3f '... Cutting blade, 3a', 3f ", 8a ', 8e' ... Gas vent hole, 3
g, 8g: Valve body bonding portion, 5, 10: Lead piece.

Claims (2)

[Claims] 1. An exterior can enclosing an organic electrolyte-based battery power generation element and also serving as a negative electrode terminal, and a positive terminal having an opening of the exterior can hermetically sealed by crimping via an insulating packing material. In an organic electrolyte battery having a sealing body that also serves as a sealing plate, the sealing body has a valve port in the center and a peripheral edge rising portion is caulked inward to fix the valve element via a ring-shaped reinforcing plate. A sealing plate, an annular positive temperature coefficient resistance element (PTC element) plate laminated on a peripheral caulking portion of the dish-shaped sealing plate, and a laminate disposed on the PTC element plate and corresponding to the valve element. And a cap having a gas vent hole formed in the projecting portion.The plate-like sealing plate has a flat bottom, so that the valve element is entirely formed in a portion excluding the valve port. Closely attached to the dish-shaped sealing plate An organic electrolyte battery. 2. The organic electrolyte battery according to claim 1, wherein the diameter of the valve opening of the sealing plate and the diameter of the central vent hole of the ring-shaped reinforcing plate are substantially the same.