JP3511698B2 - Sealed non-aqueous secondary battery - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealed non-aqueous secondary battery capable of interrupting conduction inside the battery when the internal pressure of the battery rises.

[0002]

2. Description of the Related Art In recent years, due to the high performance, miniaturization, and portability of electronic devices, the batteries used as the power source have been
Secondary batteries with high energy density have been required to replace conventional nickel-cadmium batteries and lead-acid batteries. Therefore, recently, research and development of nickel-hydrogen batteries using a hydrogen storage alloy for the negative electrode and non-aqueous secondary batteries using a substance capable of inserting and releasing light metals for the positive electrode and the negative electrode have been carried out and used for some electronic devices. Came to be. In particular, the sealed non-aqueous secondary battery that applies the insertion and release of lithium has a high battery voltage of 3.6 V and a high energy density, so the battery can be made smaller and lighter, and self-discharge is less and cycle characteristics are improved. Since it is also excellent, it is expected to be widely used as a power source for portable devices in the future.
Generally, in a sealed type secondary battery, the temperature of the battery itself rises at the time of short circuit or overcharge, the internal electrolytic solution is vaporized, and the internal pressure of the battery rises. Therefore, if this state continues, the internal pressure of the battery will continue to rise, and eventually the battery will burst, causing damage to peripheral devices. Therefore, this type of battery is equipped with an explosion-proof valve body capable of releasing the gas inside the battery to the outside when a predetermined battery internal pressure is reached. Similarly, the sealed non-aqueous secondary battery also has an explosion-proof valve body, but recently, especially when overcharged, the explosion-proof valve body was activated by the predetermined battery internal pressure to release the gas inside the battery. Nevertheless, it was found that the battery temperature still rose and the battery eventually burst. This is because the current continues to flow even after the gas is released, so the battery voltage continues to rise along with the battery temperature, and eventually an abnormal reaction such as rapid decomposition of the electrolyte or active material occurs, causing the battery temperature to rise rapidly. It is speculated to be because of this. Therefore, in order to prevent the above phenomenon, it is effective to detect the battery internal pressure or the battery temperature to completely cut off the charging current, and some proposals have already been made.

As shown in FIG. 12, a battery according to Japanese Patent Application Laid-Open No. 2-112151 has an explosion-proof valve body having a projection portion projecting toward the electrode group side in the central portion and an explosion-proof valve body in the central portion in the sealing portion. Has an insertion hole through which the projection part of is inserted, and the insulating stripper that is placed in contact with the lower surface of the explosion-proof valve body and the electrode group is led out from the one electrode plate, and the lower surface of the stripper and the projection of the explosion-proof valve body A lead plate to be welded to the lower surface of the protrusion is arranged so as to bridge the lower surface. In this case, when the battery internal pressure starts to rise due to overcharging or short circuit, the explosion-proof valve body is deformed to the side opposite to the electrode group side,
The lead plate welded to the projection of the explosion-proof valve body is peeled and / or broken at the connecting part due to the deformation of the explosion-proof valve body, the current path is interrupted, and the worst case of battery explosion is prevented. It It is to be noted that the stripper is attached to the explosion-proof valve body by concave and convex fitting using an intermediate fitting body made of resin to improve the assembling workability (JP-A-2-288063, US Pat. No. 4,943,497).
No. 4), the stripper is provided with a plurality of holes and a groove-shaped thin portion is provided on the surface of the explosion-proof valve body to improve safety (Japanese Utility Model Laid-Open No. 4-24262), projection of the explosion-proof valve body. A thin metal plate is interposed between the lower surface and the lead plate, and instead of the stripper, a metal disc having a gas through hole is used and fixed to the explosion-proof valve body with a resin-made disc holder. Proposed improvement proposals such as those in which the lower surface of the protrusion of the body is welded to a metal disk and the leads are connected to the electrode group side of the metal disk to improve safety (both JP-A-5-343043 and FIG. 13). Has been done.

However, according to the above publication, the accuracy of interrupting the current path is determined by the correlation between the fracture or peel strength of the weld and the tensile stress of the explosion-proof valve body, and is greatly influenced by the weld strength. Therefore, if there is a difference in the surface shape or surface oxidation state of the welded part, the welding strength changes, and the battery internal pressure at the time of current interruption is not constant. Also, after welding, when the lead plate is bent and the entire sealing body is inserted into the opening of the battery outer can, the bending stress generated in the lead plate acts as a tensile force or a pressing force on the welded part, reducing the welding strength. , The internal pressure of the battery may fluctuate when the current is cut off, or the weld may come off due to vibration or dropping. Furthermore, since the weld is exposed to the atmosphere inside the battery, in the case of a non-aqueous battery that uses an organic solvent as the electrolyte, the spark when the weld breaks or peels off and interrupts the current path becomes an organic solvent vapor. The battery may catch fire and explode.

In view of the above problems, it has been proposed to provide a current interruption portion on the side of the explosion-proof valve body which is not exposed to the atmosphere in the battery, opposite to the electrode group side. As shown in FIG. 14, the battery according to Japanese Patent Laid-Open No. 6-215760 has an inner lid body having a through hole in the central portion, an explosion-proof valve body on the inner lid body, and a through hole in the central portion in the sealing portion. The inner insulating packing having the above and the terminal cap are sequentially arranged, and the peripheral edge portion of the inner lid and the peripheral edge portion of the packing are respectively bent inward to sandwich the explosion-proof valve body and the terminal cap. Further, there is arranged a current interrupting lead, one end of which is sandwiched between the inner lid and the packing, and the other end of which extends through the through hole of the packing and is sandwiched between the packing and the terminal cap. In this case, when the battery internal pressure begins to rise, the explosion-proof valve body is deformed to the side opposite to the electrode group side and the current cut lead on the explosion-proof valve body is also pushed up in the same direction. Breaks and the current path is cut off.

However, in the case of the above publication, one end of the current interruption lead is pressed and clamped on the explosion-proof valve body.
When the explosion-proof valve body is deformed at the time of assembly or when the battery internal pressure rises, a crack may occur at a part of the explosion-proof valve body at the end of the current cut lead. In this case, at the time of overcharging, the gas inside the battery is discharged from the damaged part of the explosion-proof valve before the current path is cut off, and the current cut lead cannot be pushed up, which may cause the battery to burst. is there. Further, even if the current cutoff mechanism operates normally, the broken current cut leads may be in a floating state, and the broken lead pieces may come into contact with each other again to restore the current path.

Further, there has been proposed a device which detects the battery temperature instead of the battery internal pressure and shuts off the current path. As shown in FIG. 15, the battery according to Japanese Patent Laid-Open No. 5-205727 has a bimetal attached to the outer peripheral edge of a cap that also functions as a positive electrode terminal or a negative electrode terminal at its sealing portion,
A sealing plate that is electrically connected to the bimetal in a normal state and a lead plate that is led out from one electrode plate of the electrode group and is connected to the electrode group side of the sealing plate are arranged.
In this case, when the battery temperature starts to rise due to a short circuit or the like, the bimetal operates and the current path to the sealing plate is cut off to prevent abnormal overheating of the battery. When the battery temperature returns to the normal state, the bimetal is restored, the current path is restored, and the battery can be used normally again.

In the case of the above publication, it is safe when the battery temperature rises due to a short circuit, but it cannot be said that it is always safe when overcharged. That is, since the battery is of a reset type, the battery voltage gradually rises while the bimetal is repeatedly operated and restored. In this case, the battery may burst as described above.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of these circumstances. Even when an abnormality such as overcharge or a short circuit occurs, the conduction inside the battery is completely maintained at the initial stage when the internal pressure of the battery rises. It is an object of the present invention to provide a sealed non-aqueous secondary battery that can be shut off.

[0010]

According to the present invention, an electrode group composed of a positive electrode and a negative electrode capable of inserting and releasing a light metal, and a separator is housed in a bottomed battery outer can together with a non-aqueous electrolytic solution. by the sealing body serving as a fitted supported the positive or negative electrode terminals on the insulating gasket and the gasket provided on the inner periphery of the outer can opening, sealed nonaqueous secondary to external Sokan opening formed by closed in the battery, the sealing member includes a safety vent and the electrode group side to deform the opposite side with the increase in the internal pressure of the battery,-proof explosion valve vents with terminals arranged on the opposite side of the electrode group side a cap, comprising a current blocking member which is disposed between the-proof explosion valve and the terminal cap,-proof-explosion valve is dish-shaped body having a projecting flat portion projecting from the outer peripheral portion near the electrode group side , Having a groove-shaped thin portion in the protruding flat portion and an electrode in the central portion Integrally have a protrusion protruding toward the side opposite to the side, work said current blocking body by deformation of-proof explosion valve
It has been achieved by a sealed non-aqueous secondary battery characterized by being configured to operate. More specifically, when the internal pressure of the battery rises, the central projection of the explosion-proof valve acts on the current interrupter to cut off the electrical connection between the terminal cap and the positive electrode or the negative electrode. This is a sealed non-aqueous secondary battery in which the thin wall portion is broken to release internal gas.

The explosion-proof valve body that can be used in the present invention is preferably made of stainless steel, aluminum or an alloy thereof. In particular, when the sealing body also serves as the positive electrode terminal, JIS
Standard 1000 series, 3000 series, or 5000 series aluminum is preferable, and its thickness is 0.2.
~ 1 mm, especially the outer peripheral portion and the protruding flat portion have a thickness of 0.2 ~
It is preferably 0.5 mm. Further, the protrusion amount and the protrusion outer diameter of the protrusion flat portion differ depending on the battery size, but the ratio of the protrusion amount to the protrusion outer diameter is preferably 0.03 to 0.3, and particularly 0.05 to 0. It is preferably 15. The height of the protrusion at the center of the protruding flat portion is 0.5 to 1.2, and more preferably 0.7 to 1, with respect to the amount of protrusion of the protruding flat portion. The outer diameter is 1 to 4 mm, and more preferably 1.
It is preferably 5 to 2.5 mm.

The explosion-proof valve body that can be used in the present invention preferably has a displacement amount change characteristic curve that is substantially S-shaped with respect to an increase in internal pressure. Especially, in the initial stage of the rise of the internal pressure, the inclination is 0.005 to 0.05 mm / (kgf /
cm ² ), especially 0.01 to 0.03
It is preferably mm / (kgf / cm ² ). Also,
In the region where the amount of displacement increases with increasing internal pressure after the above deformation, the inclination is 1 mm / (kgf /
cm ² ) or more, especially 2 mm / (kg
It is preferably f / cm ² ) or more. Further, in the region where the inclination becomes smaller next to the above deformation, the inclination is preferably 0.02 to 0.15 mm / (kgf / cm ² ), particularly 0.03 to 0.08 mm / (k
gf / cm ² ) is preferable. Further, the thickness of the thin portion formed in the protruding flat portion is preferably at least 0.05 mm and at most 2/3 of the thickness of the protruding flat portion,
It is particularly preferable that the maximum thickness is 1/2 of the flat portion of the protrusion. Further, the width thereof is preferably 2 mm or less, and particularly preferably 0.5 mm or less. Furthermore, it is preferable that the groove-like thin portion is formed in at least a circumferential shape, and in this case, the central circumferential diameter of the groove width is 1/10 to 2/3 of the outer diameter of the protruding flat portion. It is particularly preferable that it is 1/5 to 1/2.

In the explosion-proof valve body usable in the present invention, it is preferable that the side wall of the stepped portion between the outer peripheral portion of the dish-shaped valve body and the projecting flat portion is hard to be deformed. It is preferable that the cross-sectional shape is processed into a substantially Z-shape, or that the side wall of the step portion is processed by forging so as to be thicker than the outer peripheral portion and the protruding flat portion. Further, in the case of the above forging, it is preferable that the thickness of the side wall of the step portion is 1.5 times or more the thickness of the protruding flat portion.

The current interrupter that can be used in the present invention is physically connected and conducting in a normal state, and when it is physically disconnected in an operating state, the electrical connection is interrupted and the original connection state is restored. If it is not obtainable, specifically, it is a contact type as a conduction type and the contact part is separated at the time of operation, or a welding type as a conduction type and the weld part is broken or peeled at the time of operation, Examples of the conductive form include a caulking type in which the caulking part is broken during operation, and a conductive part is a plate-shaped body, a rod-shaped body, or a linear body in which the conductive part is broken during operation. In particular, a leaf spring or a pressure contact type using a spring spring, a welding type or a caulking type in which a part of the leaf spring is connected by welding or caulking, and a thin-walled conductive portion that is cut are preferable. Also,
In addition to the above, a positive temperature coefficient of resistance element (hereinafter PTC
(Abbreviated as element) is preferably laminated.

The light metal referred to in the present invention means the periodic table 1a.
It is an element belonging to the group (excluding hydrogen) and the group 2a, preferably lithium, sodium and potassium, and particularly preferably lithium.

The active material in the positive electrode that can be used in the present invention is light.
Any material that can insert and release a metal may be used, but preferably
A transition metal oxide containing lithium, more preferably
Li _xCoO₂, Li_xNiO₂, Li_xCo_aNi
_1-aO₂, Li_xCo_bV_1-bO_z, Li_xCo_bFe
_1-bO_z, Li_xMn₂O_Four, Li_xMnO₂, LiM
n₂O₃, Li_xMn_bCo_{2- b}O_z, Li_xMn_bN
i_2-bO_z, Li_xMn _bV_2-bO_z, Li_xMn_bF
e_1-bO_z(Where x = 0.05 to 1.2, a = 0.1
~ 0.9, b = 0.8 to 0.98, z = 1.5 to 5)
is there.

The active material in the negative electrode that can be used in the present invention is light.
Any material that can insert and release a metal may be used, but preferably
Graphite (natural graphite, artificial graphite, vapor growth graphite), coke
(Coal or petroleum-based), Organic polymer fired product (Polyac
Lilonitrile resin or fiber, furan resin, crezo
Resin, phenol resin), mesoface pitch firing
A metal oxide, a transition metal oxide containing lithium,
More preferably GeO, GeO₂, SnO, Sn
O₂, SnSiO₃, PbO, PbO₂, Pb₂O₃,
Pb₃O_Four, Sb₂O₃, Sb₂O_Four, Sb₂O_Five, B
i₂O₃, Bi₂O_Four, Bi₂O_Five, Li₂SiO₃,
Li_FourSi₂O₇, Li₂Si₃O₇, Li₂Si₂O
_Five, LiSiO₆, Li₆Si₂O₇, Li₂Ge
O₃, Li_FourGeO _Four, Li₈GeO₆, Li₂SnO
₃, Li₈SnO₆, LiPbO₃, Li₂PbO₃,
Li_FourPbO_Four, LiBiO₂, Li₃BiO_Four, Li
_FiveBiO_Five, LiSbO_Four, Li₃SbO_Four, Li₂Z
nO₂, Li₃InO₃, Li₂ZnSn₂O₆, Li
_0.1SnO_2.05, Li_0.5SnO_2.25, Li_FourSn
O_Four, Li ₆SnO_Five, Li₈SnO₆, Li₂SnO
₂, Li_0.1SnO_1.05, Li_0.5SnO_1.25, LiS
nO_2.5, Li_FourSnO_Four, Li₈SnO_Five, LiMg
Sn₂ O₇, Li₂MgSn₂O_Five, SnSi_0.01O
_1.02, SnP_0.01O_1.03, SnB_0.3O_1.45, SnSi
_0.7P_0.3O_2.75, SnSi_0.7Ge_0.1P
_0.2O_3.1, SnSi_0.3Al_0.1P_0.3O_3.1, Sn
Si_0.3Al_0.1B_0.2P_0.3O_{3. 2}Is.

The conductive agent in the positive and negative electrodes which can be used in the present invention is graphite, acetylene black, carbon black, Ketjen black, carbon fiber or metal powder, metal fiber or polyphenylene derivative, and graphite or acetylene black is particularly preferable. . The binder in the positive electrode and the negative electrode that can be used in the present invention, polyacrylic acid, carboxymethyl cellulose, polytetrafluoroethylene,
Polyvinylidene fluoride, polyvinyl alcohol, starch,
Regenerated cellulose, diacetyl cellulose, hydroxypropyl cellulose, polyvinyl chloride, polyvinylpyrrolidone, polyethylene, polypropylene, SBR, E
PDM, sulfonated EPDM, fluororubber, polybutadiene, and polyethylene oxide, and particularly polyacrylic acid, carboxymethyl cellulose, polytetrafluoroethylene, and polyvinylidene fluoride are preferable.

The positive and negative electrode supports that can be used in the present invention are made of aluminum, stainless steel, nickel, titanium, or an alloy thereof for the positive electrode and copper, stainless steel, nickel, titanium for the negative electrode. Alternatively, it is an alloy of these and has a form of foil, expanded metal, punching metal, or wire mesh. In particular, aluminum foil is preferable for the positive electrode and copper foil is preferable for the negative electrode. The separator that can be used in the present invention has a large ion permeability, has a predetermined mechanical strength, and may be an insulating thin film, as a material, an olefin polymer, a fluorine polymer, a cellulose polymer, a polyimide, nylon, Glass fiber or alumina fiber is used, and as the form, non-woven fabric, woven fabric, or microporous film is used. Especially as a material
Polypropylene, polyethylene, a mixture of polypropylene and polyethylene, a mixture of polypropylene and Teflon, a mixture of polyethylene and Teflon are preferable, and a microporous film is preferable as a form. In particular, a microporous film having a pore size of 0.01 to 1 μm and a thickness of 5 to 50 μm is preferable.

The electrolytic solution which can be used in the present invention includes propylene carbonate, ethylene carbonate, and
Butylene carbonate, dimethyl carbonate, diethyl carbonate, 1,2-dimethoxyethane, γ-butyrolactone, tetrahydrofuran, 2-methyltetrahydrofuran, dimethylsulfoxide, dioxolane,
1,3-dioxolane, formamide, dimethylformamide, nitromethane, acetonitrile, methyl formate,
Methyl acetate, methyl propionate, phosphoric acid triester,
A mixture of trimethoxymethane, a dioxolane derivative, a sulfolane, a 3-methyl-2-oxazolidinone, a propylene carbonate derivative, a tetrahydro derivative, diethyl ether, and 1,3-propanesultone, and at least one kind of LiClO ₄ as an electrolyte. , L
iBF ₄ , LiPF ₆ , LiCF ₃ SO ₃ , LiCF _{3
CO 2, LiAsF 6, LiSbF 6} , LiB 10 C
l ₁₀ , lower aliphatic lithium carboxylate, LiAlC
It is preferable to dissolve at least one salt of l ₄ , LiCl, LiBr, LiI, lithium chloroborane, and lithium tetraphenylborate. Especially in a mixed solvent of propylene carbonate or ethylene carbonate and 1,2-dimethoxyethane and / or diethyl carbonate, L
It is preferable that iCF ₃ SO ₃ , LiClO ₄ , LiBF ₄ , and / or LiPF ₆ be dissolved, and it is particularly preferable that at least ethylene carbonate and LiPF ₆ are contained.

The bottomed battery outer can that can be used in the present invention is made of nickel-plated iron and stainless steel plates (SUS304, SUS304L, SUS304).
N, SUS316, SUS316L, SUS430, S
US444, etc.), nickel-plated stainless steel plate (same as above), aluminum or its alloy, nickel,
Titanium and copper, which are in the shape of a true circular cylinder, an elliptical cylinder, a square cylinder, or a rectangular cylinder. In particular, when the outer can also serves as the negative electrode terminal, a stainless steel plate or a nickel-plated iron steel plate is preferable, and when the outer can also serves as the positive electrode terminal, a stainless steel plate, aluminum, or an alloy thereof is preferable. The gasket that can be used in the present invention is, as a material, an olefin polymer, a fluorine polymer, a cellulosic polymer, a polyimide, or a polyamide,
From the viewpoint of organic solvent resistance and low water permeability, an olefin polymer is preferable, and a propylene-based polymer is particularly preferable. Further, it is preferably a block copolymer of propylene and ethylene.

The battery of the present invention is optionally covered with an exterior material. Examples of the exterior material include a heat shrink tube, an adhesive tape, a metal film, paper, cloth, paint, a plastic case, and the like. In addition, at least a part of the exterior may be provided with a portion that discolors due to heat so that the thermal history during use can be known. The battery of the present invention is assembled in a battery pack by assembling a plurality of batteries in series and / or in parallel as needed. In addition to safety elements such as positive temperature coefficient resistors, thermal fuses, fuses and / or current cut-off elements, safety circuits (such as the voltage, temperature, and current of each battery and / or assembled battery are monitored and required for the battery pack) Then, a circuit having a function of cutting off the current) may be provided. In addition to the positive and negative terminals of the entire battery pack, the battery pack must also have positive and negative terminals for each battery, temperature detection terminals for the entire battery pack and each battery, current detection terminals for the entire battery pack, etc. as external terminals. You can also In addition, the battery pack may include a voltage conversion circuit (DC-DC converter or the like). Further, the connection of each battery may be fixed by welding a lead plate, or may be fixed by a socket or the like so as to be easily attached and detached. Further, the battery pack may be provided with a display function of the remaining battery capacity, the presence / absence of charging, the number of times of use, etc.

The battery of the present invention is used in various devices.
In particular, video movies, portable VCRs with monitors, movie cameras with monitors, compact cameras,
Single-lens reflex camera, disposable camera, film with lens, notebook computer, notebook word processor, electronic notebook,
It is preferably used for mobile phones, cordless phones, beards, electric tools, electric mixers, automobiles and the like.

As described above, in the case of a non-aqueous secondary battery, when an abnormality such as overcharge or short circuit occurs, heat is generated and the battery temperature rises. Therefore, in the case of the sealed type, if overcharge or a short-circuit state continues, the electrolytic solution starts to vaporize and the internal pressure of the battery rises. In particular, in the case of an overcharged state, since the battery voltage is high, decomposition of the electrolyte or active material occurs rapidly at some point, and the battery may burst. The sealed non-aqueous secondary battery of the present invention is capable of completely and accurately interrupting the current path at the initial stage when the internal pressure of the battery rises in order to prevent the worst case of the battery bursting even in the overcharged state. Is doing. That is, since the current interrupter is arranged on the side opposite to the electrode group side of the explosion-proof valve, the battery is prevented from bursting due to ignition of the electrolyte vapor at the interrupter. Further, since the lead plate led out from the positive electrode or the negative electrode of the electrode group does not break or peel off when the current is cut off, it does not become a floating state and contact the inner wall of the battery outer can to cause an internal short circuit. Further, since the explosion-proof valve body is not a thin film structure, and the protrusion for operating the current interrupter is formed integrally with the explosion-proof valve body, the number of parts is small and the assembly workability is improved. No damage such as cracks occurs in the explosion-proof valve body during assembly or when the internal pressure of the battery rises. Therefore, the sealed non-aqueous secondary battery can be extremely safe even if an abnormality such as overcharge or short circuit occurs.

Particularly, in the explosion-proof valve body, when the groove-shaped thin portion is formed in a circumferential shape, as shown in FIG. 18, the battery internal pressure becomes higher from the elastic deformation region when the battery internal pressure is low. At the time of shifting to the plastic deformation region at the time, there is a region where it is rapidly deformed by a slight increase in internal pressure. Therefore,
By adjusting the timing of activating the current interrupter to the behavior of the explosion-proof valve element in the abrupt deformation region, it is possible to enhance the current interrupt accuracy when the battery internal pressure rises. When the cross-sectional shape of the step portion side wall between the outer peripheral portion and the projecting flat portion of the explosion-proof valve body is formed in a substantially Z shape, the step portion side wall portion is deformed when the battery internal pressure rises. Since it is difficult to do so, the displacement behavior of the protruding flat part is stable, and it is possible to reduce the variation in battery internal pressure at the time of current interruption, and it is possible to break the groove-like thin part with a small deformation amount, so It is possible to reduce the amount of protrusion of the protrusion flat portion that protrudes to the electrode group side, and thus reduce the thickness of the entire sealing body. When the thickness of the side wall of the step portion is formed by forging to be larger than the thickness of the outer peripheral portion and the protruding flat portion, the same effect as in the above case is obtained, but the shape and size of the side wall of the step portion Is more stable than the above case, it is possible to further reduce the variation in battery internal pressure when the current is cut off.

[0026]

EXAMPLES The present invention will be described in detail below with reference to examples, but the invention is not limited to the following examples without departing from the gist of the invention. The sealed non-aqueous secondary battery is shown in FIG.
As shown in, a positive electrode formed by applying a positive electrode mixture containing a positive electrode active material to a positive electrode current collector, and a negative electrode formed by applying a negative electrode mixture containing a negative electrode active material to a negative electrode current collector, a separator By accommodating the electrode group formed by winding the electrode group in the battery outer can with the insulators arranged above and below the electrode group, and further by arranging the sealing body at the opening of the outer can through the insulating gasket to seal it. Configured. At this time, the sealing body was connected to the lead plate led out from the positive electrode, and the lead plate led out from the negative electrode was electrically connected to the battery outer can, and the sealing body and the battery outer can were respectively used as a positive electrode terminal or a negative electrode terminal. Configured to work.

The positive electrode was made of LiCoO ₂ (87) as an active material.
Parts by weight), graphite (9 parts by weight) as a conductive agent, sodium polyacrylate (1 part by weight) and polytetrafluoroethylene (3 parts by weight) as binders, and these are mixed together, and water is mixed. The slurry obtained by kneading as a medium was applied to both sides of an aluminum foil (current collector: thickness 20 μm). After the coated material is dried, it is compression-molded by a calendar press machine to form a strip-shaped positive electrode (thickness 250 μm).
m) was created. The negative electrode is SnSiO as an active material.
₃ (86 parts by weight), acetylene black (3 parts by weight) and graphite (6 parts by weight) as conductive agents, and polyvinylidene fluoride (4 parts by weight) and carboxymethyl cellulose (1 part by weight) as binders. These were mixed and kneaded with water as a medium to obtain a slurry, which was applied to both surfaces of a copper foil (current collector: thickness 10 μm). The coated material was dried and compression-molded with a calendar press to form a strip-shaped negative electrode (thickness: 80 μm).

The positive electrode and the negative electrode obtained above were dehydrated and dried (far infrared heater, 150 ° C., 2 hours) in a low humidity atmosphere (dew point: -50 ° C.) and then cut into a predetermined size, and the positive electrode and the negative electrode were cut. A lead plate made of aluminum and nickel is attached to each end of the, and the positive electrode and the negative electrode are made of polypropylene microporous film separator (Celguard # 240).
0: manufactured by Hoechst Celanese Co., Ltd.) to form an electrode group. Further, this electrode group was mixed with a mixed solvent of ethylene carbonate and diethyl carbonate in a volume ratio of 2 to 8 to give a volume ratio of 0.
9 mol / l LiPF ₆ and 0.1 mol / l LiBF ₄ were dissolved together with an electrolytic solution in a true round tubular bottomed battery outer can (made of nickel-plated steel plate) to store both propylene and ethylene. A cylindrical battery having a diameter of 18 mm and a height of 65 mm was constructed by using a sealing body described later together with a gasket made of a polymerized polymer.

(Battery 1) As shown in FIG.
From the outside of the battery, a terminal cap with an exhaust hole, a current interrupter,
Composed of explosion-proof valve. First, as the current interrupter, a ring-shaped PTC element from the side of the terminal cap with an exhaust hole, a ring-shaped first conductor having a central through hole and having a protruding portion from the outer peripheral portion toward the center of the through hole, the ring. The insulating member has a ring-shaped second conductive body, and the protruding portion of the first conductive body is welded to a part of the second conductive body through the central through hole of the insulating plate. Further, the explosion-proof valve body is a dish-shaped body having a projecting flat portion projecting from the vicinity of the outer peripheral portion toward the electrode group side, and four linear groove-shaped thin portions which are circumferential and intersect with the projecting flat portion. In addition to the above, a central projection having a projection protruding to the side opposite to the electrode group side was used. A battery using the thus-configured sealing body was referred to as Battery 1. In the above current interrupter,
The first conductor is pre-processed so that the protruding portion jumps up to the terminal cap side after the welded connection with the second conductor is broken, and when the explosion-proof valve body is deformed due to an increase in battery internal pressure, the explosion-proof valve body The tip of the central protruding portion of the first contact member is configured to come into contact with the lower surface of the protruding portion of the first conductive member through the central through hole of the second conductive member and the insulating plate. The PTC element is a product name “PolySwitch” manufactured by Raychem, the first conductor is a phosphor bronze plate having a thickness of 0.15 mm, and the second conductor is a phosphor bronze plate having a thickness of 0.3 mm. Thickness of insulating plate is 0.1
A 25 mm polyester film is used, and the explosion-proof valve body is made of pure aluminum (JIS standard A1100P).
-H24) material having a thickness of 0.3 mm, the outer diameter of the protruding flat portion is 12 mm, the protruding amount is 1.3 mm, the groove thin portion has a thickness of 0.1 mm, the width is 0.5 mm, and the circumferential thickness is thin. The outer diameter of the part is 5 mm, the outer diameter of the central protrusion is 2 mm, and the height is 1 mm.
As a result, the internal pressure of the battery when the current was cut off was set to 12 kgf / cm ² .

(Battery 2) As shown in FIG. 2, as the explosion-proof valve body, the step portion side wall between the outer peripheral portion and the protruding flat portion has a substantially Z-shaped cross-section, and the protruding amount of the protruding flat portion is 1 mm. A battery configured in the same manner as the battery 1 was used as a battery 2 except that a central protrusion having a height of 0.8 mm and an outer diameter of 2 mm was used. The explosion-proof valve body was manufactured as shown in FIG. First, the plate-shaped body is formed by pressing from the plate-shaped body. Next, the size regulating bodies are arranged on the inner diameter portion and the outer diameter portion of the protruding portion, and then the protruding portion of the dish-shaped body is crushed. As a result, the cross-sectional shape of the step portion side wall between the outer peripheral portion and the protruding flat portion is formed into a substantially Z shape. Next, a protrusion is formed from the lower surface side of the protruding flat portion by press working, and a groove-shaped thin portion is further formed from the upper surface side of the protruding flat portion by press working. In the above description, as shown in FIG. 4, it is possible to add a process of reducing the outer diameter of the root portion from the outer peripheral side of the protrusion before the crushing process of the protrusion of the dish.

(Battery 3) As shown in FIG. 5, as the explosion-proof valve body, the step portion side wall between the outer peripheral portion and the projecting flat portion has a sectional thickness of 0.5 mm, and the outer peripheral portion and the projecting flat portion have the same thickness. Except that the thickness is 0.3 mm and the one formed by forging (the material is the same as that of the battery 1) so that the side wall of the stepped portion makes an angle of about 90 degrees with the outer peripheral portion, A battery having the same structure as the battery 2 was referred to as a battery 3.

(Batteries 4 and 5) A battery 1 was constructed in the same manner as the battery 1 except that the following materials were used for the explosion-proof valve body. First, the battery 4 is made of an alloy of aluminum and manganese (JIS standard A3003P-H24),
Alloy of aluminum and magnesium (JIS standard A50
52P-H34) was used as Battery 5.

(Batteries 6 and 7) A battery 2 was constructed in the same manner as the battery 2 except that the following materials were used for the explosion-proof valve body. First, a battery 6 made of an alloy of aluminum and manganese (JIS standard A3003P-H24) was used.
Alloy of aluminum and magnesium (JIS standard A50
52P-H34) was used as Battery 7.

(Batteries 8 and 9) A battery 3 was constructed in the same manner as the battery 3 except that the following materials were used for the explosion-proof valve body. First, a battery 8 made of an alloy of aluminum and manganese (JIS standard A3003P-H24) was used,
Alloy of aluminum and magnesium (JIS standard A50
52P-H34) was used as Battery 9.

(Battery 10, Battery 11, Battery 12, Battery 1
3) The battery 3 was constructed in the same manner as the battery 3 except that the thickness of the side wall of the step portion between the outer peripheral portion of the explosion-proof valve body and the protruding flat portion was as follows. First, a battery having a step portion side wall thickness of 0.3 mm is a battery 10, a battery having a thickness of 0.4 mm is a battery 11, a battery having a thickness of 0.6 mm is a battery 12, and a battery having a thickness of 0.7 mm. The battery was the battery 13.

(Battery 14) A battery constructed in the same manner as the battery 2 except that the thin portion of the explosion-proof valve body is provided in the protruding flat portion as shown in FIG. 6 in the thin portion of the explosion-proof valve body. Was used as the battery 14. The thickness of the thin portion is 0.0
The width was 8 mm and the width was 2 mm.

(Battery 15) In the thin wall portion of the explosion-proof valve body, as shown in FIG. 7, the battery 2 except that a plurality of groove-shaped thin wall portions radially formed from the central portion are provided in the projecting flat portion. A battery configured in the same manner as above was used as battery 15. In addition,
The thin portion had a thickness of 0.1 mm, a width of 0.5 mm, and a length of 2.5 mm.

(Battery 16) The battery 16 is the same as the battery 2 except that a groove-shaped thin portion formed in a circumferential shape is provided in the protruding flat portion as shown in FIG. 8 in the thin portion of the explosion-proof valve body. The configured battery was named battery 15. The thin portion has a thickness of 0.
The width was 1 mm, the width was 0.5 mm, and the outer circumference was 5 mm.

(Battery 17, Battery 18) As shown in FIGS. 13 and 14, as the sealing member, Japanese Patent Laid-Open No. 34304/1993.
The battery using the one described in Japanese Patent No. 3 was designated as Battery 17, and the battery using the one described in Japanese Patent Laid-Open No. 6-215760 was designated as Battery 18. In addition, in order to make a comparison with the batteries of the other examples, the battery internal pressure at the time of current interruption is also in this battery.
It was set to be equivalent to the case.

(Battery 19, Battery 20) As shown in FIGS. 16 and 17, as the explosion-proof valve body of the battery 17 and the battery 18,
Batteries formed by forging as in Battery 3 were used as batteries 19 and 20. The material is aluminum of JIS standard A1100P-H24, the thickness of the protruding flat portion is 0.3 mm, the amount of protrusion is 1 mm, the thickness of the side wall of the step portion is 0.5 mm, and the thin portion is the same as the battery 1.
At 0, the height of the central projection is 1 mm and the outer diameter is 2
mm.

The batteries of the examples according to the present invention and the conventional example configured as described above are subjected to a drop test from a height of 1 m onto concrete five times, and then continuously charged at a current of 3 A (ampere) at room temperature. Tests were performed (the number of drop tests was 200, and the number of continuous charge tests was 50). Table 1 shows the number of disconnections in the battery in the drop test, the number of batteries that ruptured in the continuous charge test, and the battery internal pressure at the time of current interruption of the battery in which the current interruption mechanism normally operated.

Table 1 Number of disconnections Number of ruptures Battery internal pressure (variation range) Battery 1 0 0 9 to 15 (6) Battery 2 0 0 10 to 14 (4) Battery 3 0 0 11 to 13 (2) Battery 4 0 0 9 ~ 15 (6) Battery 5 0 8-14 (6) Battery 6 0 0 9-14 (5) Battery 7 0 0 10-14 (4) Battery 8 0 0 11-14 (3) Battery 9 0 0 11 〜13 (2) Battery 10 0 0 9-14 (5) Battery 11 0 0 10-14 (4) Battery 12 0 0 11-13 (2) Battery 13 0 0 11-13 (2) Battery 14 0 0 10 〜16 (6) Battery 15 0 0 10-15 (5) Battery 16 0 0 10-14 (4) Battery 17 4 5 11-13 (2) Battery 18 0 3 10-15 (5) Battery 19 0 0 11 to 13 (2) battery 20 0 0 11~13 (2) ( kgf / cm 2)

In the above result table, the rupture of the battery 17 is
It can be inferred that three of them were because the explosion-proof valve body had cracks and the internal pressure of the battery did not rise, and two of them were sparks generated when the current was cut off, which caused ignition of the electrolyte solution vapor. In addition, the battery 18
Since the battery internal pressure did not rise to the set value, it can be inferred that the explosion was caused by cracks in the explosion-proof valve body. On the other hand, in all the other batteries according to the present invention, the current breaker worked normally and reliably, and the batteries did not burst.
Further, the explosion-proof valve body having a circumferential groove-shaped thin portion, the step-shaped sidewall of the explosion-proof valve body having a substantially Z-shaped cross section,
The one forged so that the thickness of the side wall of the stepped portion of the explosion-proof valve body is larger than the thickness of the projecting flat portion has a small variation in battery internal pressure at the time of current interruption, and has a highly accurate current interruption function. In particular, the forged one can be welded to the lower surface of the thickened central portion projection of the lead plate derived from the electrode group, so there is no problem of cracking during welding, and safety and The battery can have high reliability.

Further, in the case where the current cutoff mechanism is formed by a constant deformation of the explosion-proof valve body such as the battery 19 and the battery 20, the use of the forged explosion-proof valve body of the present invention provides high safety and reliability. It can be a battery.

Further, in the battery of the embodiment of the present invention, the current interrupting body used was one in which the welded connection portion of the first conducting body and the second conducting body was destroyed, but as shown in FIG. Part, a protrusion is provided on the second conductor, and the protrusion is formed on the first conductor.
The effect was the same as that obtained by passing through a small hole provided in the corresponding portion of the conductor, crushing the portion protruding from the small hole and fixing by caulking.

[0046]

In the sealed non-aqueous secondary battery according to the present invention, the current blocking body is provided between the explosion-proof valve body and the terminal cap, and the projection for operating the current blocking body is provided on the explosion-proof valve body itself. Since the unit is integrally provided, when an abnormality such as overcharging or a short circuit occurs, it is possible to reliably and safely interrupt the conduction inside the battery at the initial stage when the internal pressure of the battery rises. In addition, since the current interrupter can be configured separately from the explosion-proof valve element, it is possible to confirm the current interrupt function before installing it in the battery, which is a highly reliable and safe sealed non-aqueous secondary A battery can be provided.

[Brief description of drawings]

FIG. 1 is a schematic vertical sectional view showing an embodiment (battery 1) of a sealed non-aqueous secondary battery of the present invention.

FIG. 2 is a schematic vertical sectional view showing a sealing portion of an embodiment (battery 2) of the sealed non-aqueous secondary battery of the present invention.

FIG. 3 is an explanatory view of the manufacturing process of the explosion-proof valve body in FIG.

FIG. 4 is an explanatory view of another manufacturing process of the explosion-proof valve body in FIG.

FIG. 5 is a schematic vertical sectional view showing a sealing portion of an embodiment (battery 3) of the sealed non-aqueous secondary battery of the present invention.

FIG. 6 is an example of a sealed non-aqueous secondary battery of the present invention (Battery 1
4) Plan view showing the explosion-proof valve body

FIG. 7 is an example of a sealed non-aqueous secondary battery of the present invention (Battery 1
5) Plan view showing the explosion-proof valve body

FIG. 8 is an embodiment of the sealed non-aqueous secondary battery of the present invention (Battery 1
6) Plan view showing the explosion-proof valve body of 6)

FIG. 9 is an explanatory view of another example of the current cutoff switch of the sealed non-aqueous secondary battery of the present invention.

FIG. 10 is a plan view showing a first conductor of the current cutoff switch shown in FIG.

11 is a plan view showing the explosion-proof valve body in FIG.

FIG. 12 is a schematic vertical sectional view showing a sealing portion of an example of a conventional sealed battery.

FIG. 13 is a schematic vertical sectional view showing a sealing portion of an example of a conventional sealed battery.

FIG. 14 is a schematic vertical sectional view showing a sealing portion of an example of a conventional sealed battery.

FIG. 15 is a schematic vertical sectional view showing a sealing portion of an example of a conventional sealed battery.

FIG. 16 is a schematic vertical sectional view showing a sealing portion of an embodiment (battery 19) of the sealed non-aqueous secondary battery of the present invention.

FIG. 17 is a schematic vertical sectional view showing a sealing portion of an embodiment (battery 20) of the sealed non-aqueous secondary battery of the present invention.

FIG. 18 is a displacement amount characteristic curve diagram with respect to pressure of the explosion-proof valve body of the embodiment (battery 2) of the sealed non-aqueous secondary battery of the present invention.

[Explanation of symbols]

1 exterior can 2 electrode group 3 positive electrode 4 Negative electrode 5 separator 6 Upper insulating plate 7 Lower insulation plate 8 lead plate 9 gasket 10 Sealing body 11 Explosion-proof valve body 12 Current breaker 13 terminal cap 14 Positive temperature coefficient resistance element (PTC element) 15 First conductor 16 Projection 17 Ring-shaped insulating plate 18 Second conductor 19 Weld connection 20 exhaust holes 21 protruding flat part 22 Central protrusion 23 Thin part 24 strippers 25 metal discs 26 disk holder 27 Inner insulation packing 28 Inner lid 29 Current breaking lead 30 bimetal 31 Caulking connection

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-7-105933 (JP, A) JP-A-6-231743 (JP, A) JP-A-6-215746 (JP, A) JP-A-6- 215747 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01M 10/36-10/40 H01M 2/04 H01M 2/12 H01M 2/34

Claims (5)

(57) [Claims] 1. An electrode group composed of a positive electrode and a negative electrode capable of inserting and releasing light metal, and a separator is housed in a bottomed battery outer can together with a non-aqueous electrolyte solution, and is provided on the inner periphery of the outer can opening. In the sealed non-aqueous secondary battery in which the opening of the outer can is closed by the provided insulating gasket and the sealing body fitted and supported by the gasket and also serving as the terminal of the positive electrode or the negative electrode, the sealing body is An explosion-proof valve body that deforms to the side opposite to the electrode group side as the battery internal pressure increases; a terminal cap with an exhaust hole arranged on the side opposite to the electrode group side of the explosion-proof valve body; and the explosion-proof valve body. The explosion-proof valve body is a dish-shaped body having a projecting flat portion projecting from the vicinity of the outer periphery toward the electrode group side, which is provided with a current interrupting body arranged between the terminal cap and the groove-shaped body. Has a thin portion and has a protrusion projecting to the side opposite to the electrode group side at the center. A sealed non-aqueous secondary battery, characterized in that it has a starting part integrally, and the current interrupting body is configured to operate by deformation of the explosion-proof valve body. Wherein said safety vent has a sudden deformation region characteristic curve showing the history of displacement changes relative to the internal pressure rises, substantially S-shape the slope is 1mm / (kgf / cm ²⁾ or more The sealed non-aqueous secondary battery according to claim 1, wherein the sealed non-aqueous secondary battery is represented by: Wherein the safety vent is made of aluminum or its alloys, and claim 1, a portion of the groove-like thin portion of the safety vent is characterized in that it is formed at least circumferentially Alternatively , the sealed nonaqueous secondary battery according to 2. Wherein said safety vent is in any one of claims 1 to 3, characterized in that the cross-sectional shape of the step side wall between the projecting flat portion and the outer peripheral portion is a substantially Z-shape Description
Sealed non-aqueous secondary battery. Wherein said safety vent, together with molded by forging, the thickness of the stepped side wall between said outer peripheral portion the protruding flat portion, being greater than the thickness of the projecting flat portion The sealed nonaqueous secondary battery according to claim 1 .