JPH10270011A - Non-aqueous electrolytic solution battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a non-aqueous electrolytic solution battery being protected from is explosion at the time of overcharging and short-circuiting while maintaining its excellent battery performance by providing an electric current cut-off mechanism for an electric current route, which may be triggered by gas generated from an incombustible gas supplier when the battery temperature rises. SOLUTION: When a battery temperature rises due to such abnormal matters as overcharging as short-circuiting, etc., gas is generated from an incombustible gas supplier 13 and the gas pressure inside a positive electrode terminal 19 increases. On account of this pressure, cut-in grooves 17 are broken and out of a current cut-off board 14, such a part to which a positive electrode lead 15 is connected is cut in a circular shape to be capable of being removed from a positive electrode terminal 10 so as to cut off the electric connection of the positive electrode terminal 10 to positive electrode lead 15. Thereby, any rise of battery temperature can be stooped and safety in the case of emergency such as avoiding explosion can be improved, and performance deterioration caused by incombustible gas supplier can be avoided and there is no need to newly provide any space for an electric current cut-off mechanism.

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 improved current interrupt mechanism which operates in response to a rise in battery temperature.

[0002]

2. Description of the Related Art In recent years, as electronic devices such as mobile phones and VTRs have been reduced in size and demand has increased, there has been a demand for higher capacity secondary batteries which are power sources for these electronic devices. In addition, air pollution by exhaust gas from automobiles has become a social problem, and there is a demand for a lightweight and high-performance secondary battery as a power supply for electric vehicles.

As such a secondary battery, a non-aqueous electrolyte secondary battery provided with a negative electrode containing a substance capable of occluding and releasing lithium such as a carbon material has been developed and is becoming popular as a power source for portable electronic devices. This non-aqueous electrolyte secondary battery has a characteristic that it has a high electromotive force of 4 V class unlike a conventional battery, and its excellent performance has attracted attention.

[0004] However, the danger is increasing with the increase in energy density. For example, in a non-aqueous electrolyte secondary battery, when a large current flows due to a so-called overcharge state in which a current higher than usual is given at the time of charging, or a short-circuit state due to malfunction or failure of equipment in which the battery is used. However, there is a problem that the non-aqueous electrolyte is decomposed to generate gas and the internal pressure of the battery increases. Further, if overcharging or short-circuiting continues, the generated gas fills the inside of the outer can of the battery, which may cause rupture.

[0005] In order to avoid such a situation, a non-aqueous electrolyte secondary battery having a safety valve for releasing a gas filled in the battery to the outside and preventing rupture has been devised. However, such a secondary battery can prevent rupture, but (1) is excessively heated due to current flowing even after the safety valve operates, and (2) gas released outside through the safety valve is There is a problem that the battery fills the inside of a portable device or the like in which the battery is used, and the gas ignites and ignites. Therefore, when an abnormality such as an overcharge or a short circuit occurs, the current path of the battery is immediately cut off, and a function of preventing the flow of the abnormal current is added, thereby preventing a rise in the internal pressure enough to operate the safety valve. It is desired.

For this reason, a non-aqueous electrolyte battery provided with a temperature fuse for detecting a temperature rise of the battery at the time of abnormality and interrupting a current path has been proposed. However, thermal fuses
It does not work under conditions that seem to work,
If the abnormal current is too large, the abnormal current cannot be completely shut off, which may lead to rupture. Therefore, it has not been put to practical use.

Therefore, in a non-aqueous electrolyte secondary battery,
A microporous separator is used in place of this thermal fuse, and when the temperature inside the battery rises and reaches the melting point of the separator at the time of abnormality such as overcharge or short circuit, the separator melts and the pores are blocked, A so-called shutdown mechanism for stopping the reaction is employed. However, if the separator is not completely melted and micropores exist even in a part of the separator, lithium ions can move, and it becomes difficult to completely shut off the abnormal current.
Therefore, employing only the separator as a means for interrupting abnormal current is insufficient as a safety measure.

For these reasons, a non-aqueous electrolyte battery provided with a PTC element whose resistance value rapidly increases with an increase in temperature at the time of abnormality has been put to practical use. In such a battery, when a current higher than normal, such as a large current due to an overcharged state, flows, the PTC element is activated, its resistance value is rapidly increased, and the current can be cut off. It is possible to avoid a sudden rise and prevent the battery from bursting. However, while safety has been improved, there have been problems such as an increase in the number of parts charged and an increase in cost.

As means for further improving reliability, Japanese Patent Application Laid-Open No. 4-329268 discloses a positive electrode containing lithium carbonate and a metal material which is deformed by an increase in battery internal pressure. A safety valve having a bulged safety valve convex portion, a disk disposed between the safety valve and the power generating element, having a central through hole into which the safety valve convex portion is inserted, and a gas through hole through which gas passes, and the safety valve convex portion. A metal sheet welded to the part, one of which is connected to the positive electrode,
A non-aqueous electrolyte secondary battery including a lead plate having the other end connected to the lower surface of the thin metal plate is disclosed. Secondary batteries having such a structure are currently in practical use as power supplies for small electronic devices. In the battery, for example, lithium carbonate in the positive electrode is electrochemically decomposed due to overcharging to generate carbon dioxide gas, and when the internal pressure of the battery increases, pressure is applied to the safety valve through the gas through hole of the disk. When the safety valve is lifted by this pressure and the safety valve protrusion comes off the metal sheet, the electrical connection between the safety valve and the lead plate is cut off, so that the progress of the abnormal reaction is stopped and the battery temperature suddenly increases. Unnecessary rise and rupture are prevented beforehand.

However, in order to reliably shut off the current by such a method, it is necessary that the positive electrode contains at least about 0.5 to 15% by weight of lithium carbonate. This amount is larger than the amount of lithium carbonate generated as a by-product in the active material when synthesizing a positive electrode active material (for example, lithium-containing nickel oxide). Therefore, since it is necessary to newly add lithium carbonate to the positive electrode, for example, by coating the surface of the positive electrode active material with lithium carbonate, there is a problem that the packing density of the active material decreases and the battery capacity decreases. .

Further, polyvinylidene fluoride, which is suitable as a binder for the positive electrode, has low alkali resistance, so that when the amount of lithium carbonate added is excessive, the viscosity of the slurry increases, and the slurry is applied to a current collector. Therefore, there is a problem that it is difficult to produce a positive electrode.

Further, the following problems are involved in filling the electrode group not only with lithium carbonate but also with a substance which does not participate in the battery reaction. That is, when a transition metal oxide such as LiCoO ₂ is used as a positive electrode of a nonaqueous electrolyte secondary battery, substances that do not participate in the battery reaction described above are usually
The negative electrode is exposed to a reducing environment substantially equal to the lithium potential, and the positive electrode is exposed to a severe oxidizing environment exceeding 4 V. For this reason, side reactions generally tend to occur.
As a result, problems such as inhibition of the charge / discharge reaction and degradation of battery performance such as swelling of the battery and increase in internal resistance due to generation of decomposition gas are caused.

[0013]

SUMMARY OF THE INVENTION An object of the present invention is to provide a non-aqueous electrolyte battery in which bursting during overcharge and short circuit is prevented while maintaining excellent battery performance.

[0014]

According to the present invention, a power generating element including a non-aqueous electrolyte and a non-combustible gas supply which is disposed outside the power generating element and generates non-combustible gas when the battery temperature rises are provided. A non-aqueous electrolyte battery, comprising: a current cut-off mechanism that cuts off a current path of the battery by operating by generating the non-combustible gas.

According to the present invention, a container having an opening,
One electrode housed in the container, the other electrode housed in the container, and a non-aqueous electrolyte housed in the container,
A sealing plate disposed at the opening of the container, the other terminal having a hollow portion, which is disposed to penetrate the sealing plate and is accommodated in the hollow portion of the other terminal, and the battery temperature is increased. Then, a noncombustible gas supply that generates a noncombustible gas, one end is connected to the other electrode, and the other end is connected to the lower surface of the other electrode terminal, and the other inner electrode is connected to the bottom inner surface of the other electrode terminal. A groove formed so that a portion of the other electrode terminal including a portion to which the other electrode lead is connected is cut off from the other electrode terminal by generation of the incombustible gas. A non-aqueous electrolyte battery is provided.

[0016]

FIG. 1 shows an example of a rectangular non-aqueous electrolyte secondary battery which is an example of a non-aqueous electrolyte battery according to the present invention.
This will be described in detail with reference to FIG. For example, an electrode group 2 is accommodated in a bottomed rectangular cylindrical container 1 also serving as a negative electrode terminal made of mild steel. The electrode group 2 includes a positive electrode 3, a separator 4
And a laminate of the negative electrode 5 is spirally wound. The electrode group 2 is housed in a cage-shaped electrode cover 6. The non-aqueous electrolyte is contained in the container 1. The positive electrode 3 has a positive electrode mixture 3a on both surfaces of a positive electrode current collector,
3b is formed. On the other hand, the negative electrode 5 has a structure in which negative electrode mixtures 5a and 5b are formed on both surfaces of a negative electrode current collector. The electrode group 2 and the non-aqueous electrolyte form a power generating element.

A sealing body 9 made of, for example, mild steel having a circular hole 7 in the center and a rectangular pressure release hole 8 at a position adjacent to the hole 7 is formed by laser welding on the upper end opening of the container 1. It is installed airtight. For example, the positive electrode terminal 10 made of high chromium steel is inserted into the hole 7 of the sealing body 9 so that its upper and lower ends protrude from the upper and lower surfaces of the sealing body 9, and is filled in the hole 7. Hermetically sealed by a glass insulating material 11. As shown in FIG. 3, the positive electrode terminal 10 has a cylindrical shape with a closed upper end, and has a cylindrical hollow portion 12 inside. The hollow portion 12 of the positive electrode terminal 10 is filled with a nonflammable gas supply 13. The disk-shaped current interrupting plate 14 is hermetically welded to the opening of the positive electrode terminal 10. For example, a positive electrode lead 15 made of aluminum
Has one end connected to the positive electrode 3 of the electrode group 2 and the other end connected to the lead connection circular projection 1
6 are connected. V-shaped notch 17
Is formed on the upper surface of the blocking plate 14 so as to be concentric therewith. The cut groove 17 is formed such that the lower surface (the bottom of the groove 17) of the blocking plate 14 facing the groove 17 surrounds the mounting portion (the circular protrusion 16) of the positive electrode lead 15. The cut groove 17 can be formed by pressing the upper surface of the blocking plate 14 with a punch or by etching. That is, the current interruption mechanism includes the non-combustible gas supply body 13 arranged in the positive electrode terminal 10 and the cut groove 17 formed in the current interruption plate 14.

As shown in FIGS. 1 and 2, the rectangular thin plate 18 made of, for example, stainless steel is
Is hermetically mounted by laser welding so as to cover the pressure release hole 8. A straight portion and a groove 19 having a V-shaped shape at both ends are formed in the thin plate 18. That is, the pressure release hole 8 of the sealing body 9 and the thin plate 18 constitute a safety valve mechanism.

In the non-aqueous electrolyte secondary battery having such a configuration, when the battery temperature rises due to an abnormality such as overcharging or short-circuit, a non-combustible gas is generated from the non-combustible gas supply 13 and the positive electrode terminal 10 The gas pressure inside increases. The cut groove 17 is broken by this pressure, and as shown in FIG. 4, a portion of the current interrupting plate 14 including a portion to which the positive electrode lead 15 is connected is cut into a circle to form the positive electrode terminal 1.
0, and the electrical connection between the positive electrode terminal 10 and the positive electrode lead 15 can be cut off. As a result, the rise in battery temperature can be stopped, so that bursting can be avoided.

In FIGS. 1 to 3 described above, the cutout groove is formed in the current cutoff plate so as to be concentric with the cutoff plate, but the cutout groove has a bottom portion surrounding the mounting portion of the positive electrode lead. Any shape may be used as long as it is not concentric with the blocking plate. In addition, the shape of the cut groove can be various shapes such as a rectangle, an ellipse, and a triangle, in addition to a circle.

Further, in FIGS. 1 to 3 described above, the cut grooves are formed continuously, but they may be formed discontinuously as indicated by dotted lines. It is preferable that the nonflammable gas generation temperature of the nonflammable gas supply body be in a range of 100 ° C to 300 ° C. By setting the nonflammable gas generation temperature within the above range, the current path of the battery can be promptly cut off in the event of an abnormality such as overcharge or short circuit, and rupture can be prevented beforehand. If the nonflammable gas generation temperature is lower than 100 ° C., there is a possibility that the current path of the battery is interrupted during normal use. On the other hand, if the nonflammable gas generation temperature exceeds 300 ° C., the battery may burst before the current path of the battery is interrupted. A more preferable range of the nonflammable gas generation temperature is 100 ° C to 200 ° C.
° C.

As the noncombustible gas generated by the noncombustible gas supply, carbon dioxide gas is preferable in consideration of the reactivity between the positive and negative electrode active materials (particularly lithium) and the nonaqueous electrolyte.

As the non-combustible gas supply, there can be mentioned a substance which generates a non-combustible gas by causing a decomposition reaction when the battery temperature rises. Specifically, sodium hydrogen carbonate (decomposition temperature 100 ° C.), potassium hydrogen carbonate (decomposition temperature 190 ° C.), iron carbonate (decomposition temperature 200 ° C.), zinc carbonate (decomposition temperature 150 ° C.), malonic acid (decomposition temperature 135
° C), oxalic acid (decomposition temperature 187 ° C), adipic acid (decomposition temperature 153 ° C), acetoacetic acid and the like.

Particularly, dicarboxylic acids such as malonic acid, oxalic acid and adipic acid are preferred. This dicarboxylic acid easily generates a decarboxylation reaction when heated, and can quickly generate carbon dioxide gas. In addition, the carboxylic acid (weak acid) generated as a result of the decarboxylation reaction acts as an acid, Since the cut groove of the cut-off plate can be corroded, the electric current cut-off plate can be quickly cut along the cut groove to cut off the electrical connection between the positive electrode terminal and the positive electrode lead when abnormal. An example of this decarboxylation reaction (malonic acid) is shown in the following formula (1).

HOOC—CH ₂ —COOH → CO ₂ + CH ₃ COOH (1) The pressure in the positive electrode terminal when nonflammable gas is generated depends on the filling amount of the nonflammable gas supply body and the hollow portion of the positive electrode terminal. Determined based on volume. The filling amount of the incombustible gas supply and the volume of the hollow portion of the positive electrode terminal are such that the internal pressure of the battery is 5 kg.
It is preferable to set so that the cut groove is broken when f / cm ^{2 to 20} kgf / cm ² is reached.

Next, the positive electrode 3, the negative electrode 5, the separator 6
And the non-aqueous electrolyte will be described. 1) Positive electrode 3 As the positive electrode 3, for example, lithium ions are occluded.
The positive electrode material (active material), the conductive agent and the binder to be released are suspended in an appropriate solvent, and the suspension is applied to a positive electrode current collector, dried, and pressed.

As the active material, Li _x MO ₂ (where M is at least one transition metal and x is 0.05 ≦ x
.Ltoreq.1.10.). Specifically, LiCoO ₂ , LiN
iO ₂ , LiMn ₂ O ₄ , LiNi _y Co _(1-y) O ₂
(Where y represents 0 <y <1), LiNi _Z Mn
_1-Z O ₂ (where Z represents 0.5 ≦ Z <1), LiN
i _1-xy Co _x Al _y O ₂ (where x and y are 0 <x +
y <1).

Such a composite oxide is, for example, lithium,
Cobalt and nickel carbonates are used as starting materials, a predetermined amount of these carbonates are mixed, and the mixture is fired at 600 ° C. to 1000 ° C. in an oxygen-containing atmosphere (for example, an oxygen atmosphere or air). In addition, the starting material is not limited to carbonate, but can be similarly synthesized from hydroxide and oxide.

Examples of the conductive agent include acetylene black, carbon black, graphite and the like. Examples of the binder include polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVd).
F), vinylidene fluoride-tetrafluoroethylene-6
A terpolymer of propylene fluoride, an ethylene-propylene-diene copolymer (EPDM), or the like can be used. Among them, polyvinylidene fluoride is preferable because it has excellent adhesion between the substrate and the active material and binding between the active materials.

The current collector has a thickness of, for example, 10 μm to 35 μm in order to increase the specific surface area of the positive electrode 3 in a battery having a limited size so as to increase the capacity of the battery.
It is desirable to use a thin metal plate. Examples of the metal thin plate include aluminum foil, aluminum mesh, aluminum punched metal, aluminum lath metal, and stainless steel foil.

2) Negative Electrode 5 The negative electrode 5 contains a negative electrode material that stores and releases lithium ions as an active material.

Examples of the negative electrode material include a carbonaceous material, a chalcogen compound, a metal oxide, and a light metal. Examples of the carbonaceous material include pyrolytic gas phase carbons, cokes (pitch coke, needle coke,
Petroleum coke, etc.), graphites (natural graphite, artificial graphite, fibrous graphite, spherical graphite, etc.), glassy carbons, organic polymer compounds (phenol resin, furan resin, etc. fired at an appropriate temperature), Particularly, mesophase pitch-based carbon is preferable. Among the mesophase pitch-based carbon, 2500
Mesophase pitch-based carbon fiber graphitized at a temperature of
Mesophase spherical carbon graphitized at 500 ° C. or higher is preferred. Such a carbon fiber or a negative electrode containing spherical carbon is preferable because the capacity is increased.

The carbonaceous material has an exothermic peak at 700 ° C. or higher in differential thermal analysis, more preferably an exothermic peak at 800 ° C. or higher, and the (101) diffraction peak (P ₁₀₁ ) of the graphite structure by X-ray diffraction and (P ₁₀₁ ) 100) intensity ratio P ₁₀₁ / P ₁₀₀ of a diffraction peak (P ₁₀₀₎ is preferably in the range of 0.7 to 2.2. Since the negative electrode containing such a carbonaceous material can rapidly store and release lithium ions, the rapid charging and discharging performance of the secondary battery is improved.

Examples of the chalcogen compound include titanium disulfide (TiS ₂ ), molybdenum disulfide (MoS ₂ ), niobium selenide (NbSe ₂ ), and tin oxide (SnO ₂ ). When such a chalcogen compound is used for the negative electrode, although the voltage of the secondary battery drops, the capacity of the secondary battery is improved because the capacity of the negative electrode is increased. Further, since the negative electrode has a high diffusion rate of lithium ions, the rapid charge / discharge performance of the secondary battery is improved.

Examples of the light metal include aluminum, aluminum alloy, magnesium alloy, lithium metal, lithium alloy and the like. The negative electrode containing the carbonaceous material can be manufactured, for example, by the methods (a) and (b) described below.

(A) The carbonaceous material, the binder and, if necessary, the conductive agent are suspended in a suitable solvent, and the resulting mixture coating liquid is applied to a negative electrode current collector, dried, and dried. The negative electrode is manufactured by cutting to a size of.

(B) kneading the carbonaceous material and the binder,
The negative electrode is manufactured by molding into a pellet shape or a sheet shape and sticking it to a current collector. Examples of the binder include polytetrafluoroethylene (PTF)
E), polyvinylidene fluoride (PVdF), ethylene-
Propylene-diene copolymer (EPDM), styrene
Butadiene rubber (SBR) or the like can be used.

Examples of the conductive agent include graphite and acetylene black. As the current collector, the negative electrode 5 is used in a battery having a limited size.
In order to increase the specific surface area of the battery and increase the capacity of the battery, for example, it is desirable to use a thin metal plate having a thickness of 10 μm to 35 μm. As the metal sheet, for example,
Copper foil, copper mesh, copper punched metal, copper lath metal, stainless steel foil, nickel foil, and the like can be used.

3) Separator 4 The separator 4 can be formed from, for example, a nonwoven fabric, a polyethylene microporous film, a polypropylene microporous film, a polyethylene-polypropylene microporous laminated film, a porous paper, or the like.

4) Non-aqueous electrolyte The non-aqueous electrolyte is obtained by dissolving an electrolyte (lithium salt) in a non-aqueous solvent.

Examples of the non-aqueous solvent include ethylene carbonate (EC) and propylene carbonate (PC).
And cyclic carbonates such as dimethyl carbonate (DMC), methyl ethyl carbonate (MEC) and diethyl carbonate (DEC), 1,2-dimethoxyethane (DME), diethoxyethane (DEE) and ethoxymethoxyethane. Such as chain ethers, cyclic ethers and crown ethers such as tetrahydrofuran (THF) and 2-methyltetrahydrofuran (2-MeTHF), and γ-butyrolactone (γ-B
L) and the like; nitrogen compounds such as acetonitrile (AN); and sulfur compounds such as sulfolane (SL) and dimethylsulfoxide (DMSO). The non-aqueous solvents may be used alone or as a mixture of two or more.

Among them, (1) a mixed solvent of at least one selected from EC, PC and γ-BL;
At least one selected from C, PC and γ-BL;
DMC, MEC, DEC, DME, DEE, THF, 2
-It is desirable to use a mixed solvent comprising at least one selected from MeTHF and AN. When a negative electrode containing a carbonaceous material that occludes and releases lithium ions is used, from the viewpoint of improving the cycle life of a secondary battery including the negative electrode, (a) EC, PC, and γ-BL
(B) a mixed solvent composed of EC, PC and MEC, (c) a mixed solvent composed of EC, PC and DEC, (d) a mixed solvent composed of EC, PC and DEE,
(E) mixed solvent consisting of EC and AN, (f) EC and ME
C, a mixed solvent of (g) PC and DMC, (h) a mixed solvent of PC and DEC, (i) E
It is preferable to use a mixed solvent composed of C and DEC.

Examples of the electrolyte include lithium perchlorate (LiClO ₄ ) and lithium hexafluorophosphate (Li
PF ₆ ), lithium borofluoride (LiBF ₄ ), lithium arsenic hexafluoride (LiAsF ₆ ), lithium trifluorometasulfonic acid (LiCF ₃ SO ₃ ), lithium aluminum tetrachloride (LiAlCl ₄ ), lithium bistrifluoromethylsulfonylimide [LiN (CF ₃ SO
₂ ) ₂ ] and the like. Among them, LiPF ₆ , LiBF ₄ , LiN (CF ₃ SO ₂ ) ₂
The use of is preferred because conductivity and safety are improved.

The amount of the electrolyte dissolved in the non-aqueous solvent is as follows:
It is preferable to set the range of 0.5 mol / l to 1.5 mol / l. As described in detail above, the non-aqueous electrolyte battery according to the present invention includes a power generation element including a non-aqueous electrolyte, and a non-flammable gas that is disposed outside the power generation element and generates a non-flammable gas when the battery temperature increases. A current cut-off mechanism that has a supply body and operates by generating the non-combustible gas to cut off a current path of the battery. In such batteries, for example, overcharging,
When the battery temperature rises due to an abnormality such as a short circuit, a non-combustible gas is generated from the non-combustible gas supply, and the current cutoff mechanism operates, so that the current path of the battery can be cut off. As a result, the battery can be prevented from being ruptured at the time of an abnormality as described above, and safety can be improved. In addition, since the attachment portion of the non-combustible gas supply is not a power generation element, the battery can prevent performance degradation due to the non-combustible gas supply.

Further, a non-aqueous electrolyte battery according to the present invention includes a container having an opening, one electrode housed in the container, the other electrode housed in the container, and a housing housed in the container. Non-aqueous electrolyte solution, a sealing plate arranged at the opening of the container, the other electrode terminal having a hollow portion, arranged to penetrate the sealing plate, and a hollow portion of the other electrode terminal And a non-combustible gas supply that generates non-combustible gas when the battery temperature rises, and a second electrode lead having one end connected to the other electrode and the other end connected to the lower surface of the other electrode terminal, A groove formed in the bottom inner surface of the other pole terminal so that a portion of the other pole terminal including a portion to which the other pole lead is connected is cut off from the other pole terminal by generation of the nonflammable gas. And In the nonaqueous electrolyte battery having such a configuration, when the battery temperature rises due to an abnormality such as overcharge or short circuit, a nonflammable gas is generated from the nonflammable gas supply body, and the gas pressure in the other terminal increases. I do. The gas pressure can break the groove, remove the other electrode lead from the other electrode terminal, and cut off the current path of the battery. As a result, since the battery can stop the temperature rise, the battery can be prevented from explosion. Further, since the non-combustible gas supply body is not disposed in the power generating element such as an electrode but in the other electrode terminal, it is possible to prevent deterioration of battery performance due to the supply body. Furthermore, since the non-combustible gas supply is arranged in the existing member called the other pole terminal and a groove is formed in the bottom inner surface of this terminal, a current interruption mechanism is constituted. Therefore, it is not necessary to provide an extra space, and a decrease in energy density can be avoided. Therefore, such a battery is useful not only as a power source for a portable electronic device but also as a power source for an electric vehicle.

[0046]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings. (Example 1) <Preparation of positive electrode> Nickel hydroxide {Ni (OH) ₂ }, lithium hydroxide monohydrate (LiOH · H ₂ O) were mixed with Li and N
i is mixed so that the molar ratio of i becomes 1: 1.
By calcining at a temperature of 700 ° C. for 5 hours, LiNiO ₂ powder as a positive electrode active material was obtained.

Polyvinylidene fluoride is converted to N-methyl-2-
The LiNiO ₂ powder and acetylene black are added to the solution dissolved in pyrrolidone, and these are stirred and mixed, whereby LiNiO ₂ is 90% by weight, acetylene black is 5% by weight, and polyvinylidene fluoride is 5% by weight. A positive electrode mixture was prepared. The obtained mixture was applied to both sides of an aluminum foil as a current collector, dried, and then pressed by a roller press to produce a positive electrode. <Preparation of Negative Electrode> Mesophase pitch carbon fiber using mesophase pitch as a raw material under an argon atmosphere at 1000 ° C.
After carbonization, the average fiber length is 30 μm, the average fiber diameter is 11 μm, the particle size is 1 to 80 μm, 90% by volume is present, and the particles having a particle size of 0.5 μm or less are 5% or less. After pulverization, carbonization was performed by graphitizing at 3000 ° C. in an argon atmosphere.

Polyvinylidene fluoride is converted to N-methyl-2-
The carbonaceous material was added to the solution dissolved in pyrrolidone, and the mixture was stirred and mixed to prepare a negative electrode mixture having a mixture composition of 94.3% by weight of the carbonaceous material and 5.7% by weight of polyvinylidene fluoride. This was applied to both sides of a copper foil as a current collector, dried, and then pressed with a roller press to produce a negative electrode. <Preparation of non-aqueous electrolyte> Lithium hexafluorophosphate (LiP
F ₆ ) in a mixed solvent of ethylene carbonate (EC) and methyl ethyl carbonate (MEC) (mixing volume ratio 1:
1 mol / 1 was dissolved in 2) to prepare a non-aqueous electrolyte.

The positive electrode, a separator made of a microporous polypropylene film having a thickness of 25 μm, and the negative electrode were laminated in this order, and then wound in a spiral. The obtained wound product was compressed at a pressure of 10 kgf / cm ² to produce a flat electrode body. Next, a bottomed rectangular cylindrical outer container made of mild steel (battery size: 14.5 × 42.0 × 6)
8.0 mm), the electrode body was housed in a state covered with a copper cover, and the nonaqueous electrolyte was housed therein.

It has a disk shape, a diameter of 8 mm and a thickness of 5 mm.
A current interruption plate made of aluminum and having a thickness of 0 μm was prepared. A circular projection for connecting a positive electrode lead having a diameter of 2 mm was attached to the center of the first surface of the blocking plate. On the second surface of the blocking plate, the outer diameter is 3 mm so as to be concentric with the blocking plate,
A V-shaped cut groove having a depth of 35 μm was formed. The cut groove is formed so that the bottom surrounds the circular protrusion. Next, sodium bicarbonate (decomposition temperature: 100 ° C.) was filled as an incombustible gas supply into the inside of a bottomed cylindrical positive electrode terminal (hollow volume: 58.9 mm ³ ) made of high chromium steel and having an inner diameter of 5 mm. The filling amount of the incombustible gas supply is set so that the cut groove is broken when the internal pressure of the battery reaches 10 kgf / cm ² (calculate the pressure in the hollow portion when the incombustible gas is generated. ) And 5 mg. The current blocking plate was welded to the upper opening of the positive electrode terminal so as to cover the opening, and the second surface was opposed to the inert gas supply body, and sealed.

Subsequently, a rectangular sealing body made of stainless steel having a circular hole at the center and a rectangular pressure release hole at a location adjacent to the hole was prepared. The positive electrode terminal is hermetically sealed in the circular hole of the sealing body, and a stainless steel plate having a linear portion and a groove having a V-shaped shape at both ends is formed on the upper surface of the sealing body to release the pressure. Laser welding was performed so as to close the hole and the opening of the groove was directed toward the inside of the container. Subsequently, an end of an aluminum positive electrode lead connected to the positive electrode in the container was welded to the protrusion of the current interrupting plate.

Then, the sealing body is welded to the upper opening of the container, thereby having the structure shown in FIGS. 1 to 3 described above, and having a design rated capacity of 2.9 Ah. Was assembled. (Example 2) In the above-mentioned hollow portion inside the positive electrode terminal, potassium hydrogen carbonate (decomposition temperature 190
(° C.) except that 7 mg was charged. A prismatic nonaqueous electrolyte secondary battery having the same configuration as in Example 1 was assembled. (Example 3) 4 m of malonic acid (decomposition temperature: 135 ° C) was supplied as a nonflammable gas supplier in the hollow portion inside the positive electrode terminal described above.
A prismatic nonaqueous electrolyte secondary battery having the same configuration as in Example 1 except for filling with g was assembled. (Example 4) A rectangular non-aqueous electrolyte solution having the same structure as in Example 1 except that the above-mentioned hollow portion inside the positive electrode terminal was filled with 3 mg of oxalic acid (decomposition temperature: 187 ° C) as a nonflammable gas supply. The next battery was assembled. (Comparative Example 1) A prismatic nonaqueous electrolyte secondary battery having the same configuration as in Example 1 except that the above-described hollow portion inside the positive electrode terminal was not filled with the nonflammable gas supply body was assembled.

Twenty obtained secondary batteries of Examples 1 to 4 were prepared. These secondary batteries were exposed to a temperature condition of 100 ° C. for 10 minutes, and the operating state of the current cutoff mechanism was examined. The current interruption mechanism did not operate in any of the secondary batteries, and it was confirmed that normal use was not hindered.

Twenty secondary batteries of Examples 1 to 4 and Comparative Example 1 were prepared and subjected to a battery capacity test. The charging was performed at a constant current up to 4.2 V, then at a constant voltage of 4.2 V, for a total of 8 hours. The charging current value is rated capacity.2.
Assuming 9Ah, it was set to 1 / 8C (0.36A). The discharge was performed at a constant current (1 / 5C, 0.58A) up to 2.7V. The rest time after charging and discharging was 30 minutes, respectively. When the discharge capacity of the first cycle among the charge and discharge under such conditions was measured, Examples 1 to 4 and Comparative Example 1
The discharge capacity of the secondary battery was within the range of 2.8 to 3.0 Ah, and some of them exceeded the rated capacity. The average discharge voltage of these secondary batteries was 3.66 V, and the volume energy density was 256 Wh / L.

Further, 20 rechargeable batteries of Examples 1 to 4 and Comparative Example 1 were prepared, and the rechargeable batteries were subjected to an overcharge test with a charging current of 2.9 A, thereby generating large heat and ignition. Alternatively, the rate of occurrence of batteries having abnormalities such as rupture was examined, and the results are shown in Table 1 below.

Table 1 Occurrence rate of batteries with abnormalities Example 1 10% Example 2 5% Example 30 0% Example 4 0% Comparative Example 1 100% As is clear from Table 1, outside the power generating element Example 1 having a non-combustible gas supply that generates non-combustible gas when the battery temperature rises, and has a current cut-off mechanism that operates by generating the non-combustible gas to cut off the current path of the battery ~ 4
In Comparative Example 1, the percentage of batteries in which abnormalities such as excessive heat generation, ignition, or rupture occurred during overcharging was determined.
It turns out that it is low compared with. In particular, in the secondary batteries of Examples 3 and 4 in which the nonflammable gas supply body is dicarboxylic acid, it can be seen that the number of batteries in which an abnormality occurred during overcharge is negligible.
This indicates that the use of a non-combustible gas supply in which an acid is generated when a non-combustible gas is generated enables the current cutoff mechanism to be reliably operated at a target battery temperature.

In order to assemble a conventional non-aqueous electrolyte battery provided with a current interrupting mechanism for disposing a non-flammable gas supply in a power generating element, a non-flammable gas supply is applied to a positive electrode containing LiNiO ₂ as an active material as follows. Tried to add lithium carbonate. (Comparative Example 2) After mixing 95% by weight of LiNiO ₂ powder and 5% by weight of lithium carbonate as in Example 1 using a ball mill, a solution obtained by dissolving polyvinylidene fluoride in N-methyl-2-pyrrolidone was added. The above-mentioned mixed powder and acetylene black were added, and these were stirred and mixed to prepare a positive electrode mixture comprising the mixed powder of 90% by weight, acetylene black of 5% by weight, and polyvinylidene fluoride of 5% by weight. The viscosity of the coating liquid immediately after preparation was about 5000 mPa · s. Since this coating solution was cured in a short time, a positive electrode could not be produced. In the above-described embodiment, an example in which the invention is applied to a non-aqueous electrolyte secondary battery is described. However, the non-aqueous electrolyte battery according to the present invention can be applied to a primary battery.

[0058]

As described in detail above, according to the present invention, while maintaining excellent battery performance, the current path of the battery is promptly cut off in the event of an abnormality such as a short circuit or overcharge to prevent rupture. Thus, a non-aqueous electrolyte battery with high safety can be provided. Further, according to the present invention, it is possible to improve the safety in the event of an abnormality such as a short circuit or overcharging, to avoid performance degradation due to the non-combustible gas supply, and to reduce the space for the current interruption mechanism. It is not necessary to newly provide a nonaqueous electrolyte battery which is useful as a power source for portable electronic devices and electric vehicles.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a main part of an example of a nonaqueous electrolyte battery according to the present invention (for example, a rectangular nonaqueous electrolyte battery).

FIG. 2 is a longitudinal sectional view showing the rectangular nonaqueous electrolyte battery of FIG.

FIG. 3 is a longitudinal sectional view showing a current interrupting mechanism of the rectangular nonaqueous electrolyte battery of FIG.

FIG. 4 is a longitudinal sectional view showing a state in which the current cutoff mechanism shown in FIG. 3 is operated.

[Explanation of symbols]

9: Sealing body, 10: Positive electrode terminal, 12: Hollow portion, 13: Non-combustible gas supply member, 14: Current blocking plate, 16: Positive electrode lead, 17: Cut groove.

Claims (3)

[Claims] 1. A power generating element including a non-aqueous electrolyte, and a non-combustible gas supply disposed outside the power generating element and generating a non-flammable gas when a battery temperature rises, wherein the non-flammable gas is generated. And a current cut-off mechanism that cuts off the current path of the battery by operating the battery. 2. A container having an opening, one electrode housed in the container, the other electrode housed in the container, a non-aqueous electrolyte housed in the container, A sealing plate disposed in the opening, the other terminal having a hollow portion disposed so as to penetrate the sealing plate, and being housed in the hollow portion of the other terminal, being nonflammable when the battery temperature rises A non-combustible gas supply that generates gas; a second electrode lead having one end connected to the other electrode and the other end connected to the lower surface of the other electrode terminal; a bottom inner surface of the other electrode terminal; And a groove formed so that a portion of the pole terminal including a portion to which the other pole lead is connected is cut off from the other pole terminal by generation of the incombustible gas. Electrolyte battery. 3. The nonaqueous electrolyte battery according to claim 1, wherein the nonflammable gas supply body is a dicarboxylic acid.