JPH11329497A - Lithium secondary battery, electrolytic solution thereof, and electric equipment using the battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lithium secondary battery capable of safely stopping the functions of the battery without being followed by a sudden change in appearance, generation of gas, or a change in pressure, in the event of over- charge, over-discharge, or an abnormal temperature rise, and provide an electrolyte therefor and an electric apparatus using the battery as a power supply. SOLUTION: In a lithium secondary battery having a negative electrode 11 capable of storing/discharging lithium, a positive electrode 10 capable of storing/discharging lithium, and a nonaqueous electrolyte, the nonaqueous electrolyte is solidified by a thermal reaction at a fixed temperature. The nonaqueous electrolyte has a lithium salt and a nonaqueous solvent, the nonaqueous solvent comprises a nonaqueous solvent capable of dissolving the lithium salt and a thermopolymerizable nonaqueous solvent, the nonaqueous solvent capable of dissolving the lithium salt is of 50 to 95 vol.%, preferably 65 to 90 vol.%, while the thermopolymerizing nonaqueous solvent is of 5 to 50 vol.%, preferably 10 to 35 vol.%, and the nonaqueous solvent is thermopolymerized and solidified by over-charge, over-discharge, or an abnormal temperature rise.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lithium secondary battery, and more particularly to a rechargeable lithium secondary battery having a self-protection type safety function and improved safety.
The present invention relates to an electrolytic solution for a secondary battery and an electric device using the same.

[0002]

2. Description of the Related Art A lithium secondary battery has a high voltage and a high energy density, and has excellent storage performance and repetitive charge / discharge characteristics, and is widely used in portable consumer electric products.
Also, research and development for increasing the size of this battery and using it as a nighttime power storage device for electric vehicles and homes for leveling power demand have been actively conducted. It is a product that should be widely used in daily life as clean energy that can be expected to have a great effect on preventing global warming and environmental pollution due to carbon dioxide emissions.

However, a flammable organic solvent is used in this battery due to its reactivity with lithium and restrictions on the potential window. When the battery temperature rises due to overcharging or external heating, the electrolyte heats up. It causes a runaway reaction, generating flammable gas and increasing the internal pressure of the battery, which is released out of the battery can, causing ignition and, in the worst case, an explosion. That is, it is no exaggeration to say that the spread of this battery in the above-mentioned applications lies in ensuring safety. In lithium batteries using a carbon material as an active material for the negative electrode, carbonates are generally used because they show good battery characteristics. Above all, a five-membered ring compound such as ethylene carbonate or 1,2-propylene carbonate has a high dielectric constant and is easily dissociated from a lithium salt, and is therefore called a main solvent and used as an essential solvent. These compounds have the formula 1 when heated or overcharged.

[0004]

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[0005] A decomposition reaction as shown in the following occurs to generate flammable gas. This flammable gas raises the internal pressure of the battery and is released from the battery can, causing a fire or the like in the worst case.

Therefore, Japanese Patent Application Laid-Open No. 6-290793 discloses that a solvent which causes a polymerization reaction by LiPF _{6 as a} lithium salt is mixed as an electrolyte solvent, and when the battery temperature rises, the electrolyte is converted from a decomposition reaction to a polymerization reaction. Means for avoiding ignition or explosion of a battery are disclosed. Further, JP-A-6-283206 and JP-A-9-45369 disclose a polymerization initiator and a polymerizable substance which are microencapsulated and contained in an electrolytic solution or a separator, etc. A method for releasing the active substance and curing the electrolyte is disclosed.

[0007]

In JP-A-6-290793, a solvent causing a polymerization reaction by LiPF ₆ is limited, and it is essential to mix cyclic ethers, but this is not preferable in terms of battery characteristics. Cannot be used.
That is, a differential thermal analysis shows the heat generation behavior during heating of an electrolyte solvent in which ethylene carbonate (EC) and ethyl methyl carbonate (EMC), which are carbonate solvents exhibiting good battery characteristics with respect to a carbon anode, are mixed at a ratio of 1: 1. Law (DS
As a result of the analysis in C), the solvent alone did not generate a large amount of heat, whereas the electrolytic solution in which LiPF ₆ was dissolved at 1 mol / liter showed a sharp reaction at around 250 ° C., decomposing the carbonate solvent, and Of gas.
This means that the infrared spectrum of the sample after the test was analyzed. As a result, the absorption due to the carbonyl group of the carbonate molecule remained at 1700 cm ⁻¹ in the sample containing only the solvent, whereas 1 mol / liter of LiPF ₆ was dissolved. This absorption disappeared in the electrolyte sample. That is, it is presumed that the reaction of the above-described formula 1 proceeds and lithium carbonate and ethylene gas are generated. Therefore, LiPF ₆ cannot be effectively used as a polymerization initiator in a system using a carbonate solvent as a main solvent.

Further, Japanese Patent Application Laid-Open Nos. Hei 6-283206 and
When using the microcapsules described in No. 45369, the temperature at which the polymerization initiator or the polymerization agent is released can be controlled by the material of the wall material of the microcapsules. It is difficult to contain a large amount. When the capsules are dispersed, since the reaction proceeds microscopically and locally, it is difficult to prevent the thermal runaway reaction from proceeding unless the polymerization reaction proceeds at a considerably high reaction rate.

An object of the present invention is to provide a lithium secondary battery capable of safely stopping the function of a battery without a sudden change in appearance, gas generation or pressure change upon overcharge, overdischarge, or abnormal temperature rise. An object of the present invention is to provide a battery, an electrolytic solution thereof, and an electric device using the battery as a power source.

[0010]

SUMMARY OF THE INVENTION The present invention relates to a lithium secondary battery comprising a negative electrode capable of inserting and extracting lithium, a positive electrode capable of inserting and extracting lithium, and a non-aqueous electrolyte.
The non-aqueous electrolyte is solidified by a thermal reaction at a predetermined temperature.

The non-aqueous solvent in which the lithium salt can be dissolved is 50 to
95% by volume, preferably 65 to 90% by volume, and the thermopolymerizable nonaqueous solvent is 5 to 50% by volume, preferably 10 to 35% by volume.

The above-mentioned non-aqueous electrolyte has a lithium salt and a non-aqueous solvent. The non-aqueous solvent has a non-aqueous solvent capable of dissolving the lithium salt and a thermopolymerizable non-aqueous solvent, It is characterized by being thermally polymerized and solidified by electric discharge or abnormal temperature rise.

According to the present invention, in a lithium secondary battery having a negative electrode capable of inserting and extracting lithium, a positive electrode capable of inserting and extracting lithium, and a non-aqueous electrolyte, there has been overcharge, overdischarge, or abnormal temperature rise. At this time, the apparatus is characterized in that it stops in a non-return state without a sudden change in appearance, gas generation or pressure change, especially without an increase in pressure.

The present invention provides an electrolyte for a lithium secondary battery, comprising a lithium salt and a non-aqueous solvent capable of dissolving the lithium salt, wherein the electrolyte is solidified by a thermal reaction at a predetermined temperature.

According to the present invention, there is provided an electric apparatus using the above-described lithium secondary battery as a power supply.

According to the present invention, in an electric device using a lithium secondary battery as a power source, the protection means against overcharge, overdischarge or abnormal temperature rise of the secondary battery is free from detection of temperature and pressure of the battery. A voltage or current detecting means for the battery and a control means for opening and closing the power supply based on the detected value. The operation of the battery is stopped in the return state.

The above-described electric equipment is used as an application to an electric vehicle or a power storage device.

In the present invention, a sudden change in appearance or a change in appearance due to a sudden gas generation and a sudden change in pressure means a diameter of preferably not less than 0.5 mm so that the appearance can be measured as deformation. , Which means that deformation occurs with an increase in width or height, and stops the operation as a battery before the appearance is damaged.

In the present invention, the non-returned state can be achieved by solidifying the electrolyte, making the electrolyte non-conductive so as to have a high resistance, and further oxidizing the lithium salt to an oxide. .

According to the present invention, a carbonate solvent having good battery characteristics can be used, and most of the electrolytic solution is polymerized at 100 ° C. or higher by a reaction with a positive electrode or a negative electrode before the solvent is decomposed by a thermal runaway reaction. , To solidify and safely deactivate the battery. That is, in order to solidify the electrolyte solution solvent by heat in a short time, it is advantageous to keep the reaction initiator and the like dissolved in the electrolyte solution. In this case, the reaction does not react with the electrolyte solution at room temperature, It is also necessary to be electrochemically stable within a predetermined driving potential range, and furthermore, it is necessary to react with the solvent at a lower temperature than the reaction with the charging positive electrode or the charging negative electrode. That is, the problem can be solved by dissolving in a carbonate-based solvent and mixing with a heat-reactive solvent that can be used within a range that does not impair the battery characteristics.

That is, at 100 ° C. in the presence of a suitable polymerization initiator.
It can be achieved by coexisting with a suitable polymerization initiator a 6-membered ring carbonate which undergoes anionic or cationic polymerization in the vicinity, or a 7 or more-membered ring sulfite which undergoes a polymerization reaction without removing sulfur dioxide. Further, a chain diphenyl carbonate derivative also functions as a polymerization initiator. That is, a diphenyl carbonate derivative, a carbonate derivative having 6 or more membered rings, and a sulfite derivative having 7 or more membered rings are used in a state of being compatible with an electrolyte of a carbonate-based solvent. It is also achieved by dissolving and using a polymerization initiator.

The organic solvent for maintaining the conductivity of lithium ions constituting the non-aqueous electrolyte is ethylene carbonate, propylene carbonate, butylene carbonate, pentylene carbonate, hexylene carbonate, heptalene carbonate, octalene carbonate, dimethyl carbonate, diethyl Carbonate, dipropyl carbonate, dibutyl carbonate, dipentyl carbonate, dihexyl carbonate, diheptyl carbonate, dioctyl carbonate, methyl ethyl carbonate, methyl propyl carbonate, methyl butyl carbonate, methyl pentyl carbonate, methyl hexyl carbonate, methyl heptyl carbonate, methyl octyl carbonate, Ethyl propyl carbonate, ethyl butyl carbonate , Ethylpentyl carbonate, ethylhexyl carbonate, ethyl heptyl carbonate, ethyl octyl carbonate, propyl butyl carbonate, propyl pentyl carbonate, propyl hexyl carbonate, propyl heptyl carbonate, propyl octyl carbonate, butyl pentyl carbonate, butyl hexyl carbonate, butyl heptyl carbonate, butyl octyl carbonate Carbonate, petylhexyl carbonate, petylheptyl carbonate, petyloctyl carbonate, hexylheptyl carbonate, hexyloctylcarbonate, heptyloctylcarbonate, dioxolane, γ-butyrolactone, tetrahydrofuran, 2-methyltetrahydrofuran, and halogen derivatives thereof, Examples include lactone derivatives, lactam derivatives, phosphate derivatives, phosphazene derivatives and the like.

As the heat-reactive or heat-polymerizable non-aqueous solvent, a heterocyclic compound having 6 or more members is preferable. In particular,
6- to 10-membered cyclic carbonate derivatives, particularly 1,3-
Propylene carbonate, 1,3-butylene carbonate, 1,4-butylene carbonate, 1,5-pentylene carbonate, 1,6-hexylene carbonate,
1,7-heptylene carbonate, 1,8-octylene carbonate and their alkyl-substituted derivatives, allyl-substituted derivatives, aromatic-substituted derivatives, nitro-substituted derivatives,
Amino-substituted derivatives, halogen-substituted derivatives, diphenyl carbonate, di (nitrophenyl) carbonate, di (methylphenyl) carbonate, di (methoxyphenyl) carbonate, di (aminophenyl) carbonate, 7-11 membered ring sulfite derivatives, especially , 1,4
-Butylene sulphite, 1,5-pentylene sulphite, 1,6-hexylene sulphite, 1,7-heptylene sulphite, 1,8-octylene sulphite and their alkyl-substituted, allyl-substituted derivatives, Examples include aromatic substituted derivatives, nitro substituted derivatives, amino substituted derivatives, halogen substituted derivatives and the like.

The heat-reactive organic solvent used in the present invention is a polymer that solidifies itself by thermally polymerizing the electrolytic solution, but also thermally polymerizes the non-aqueous solvent itself capable of dissolving the lithium salt. Is toward solidification.

Further, these non-aqueous solvent thermal reaction initiators are substances to which a substance for lowering the initiation temperature of the thermal polymerization is added, and specifically, iodine, lithium iodide, lithium fluoride,
Lithium bromide, lithium chloride, sodium tetrakis (4-fluorophenyl) borate, lithium tetrakis (4-fluorophenyl) borate, isoazobutylnitrile,
1,1'-azobis (cyclohexane-1-carbonitrile), 2,2'-azobis (2-methyl-N- (1,
1-bis (hydroxymethyl) ethyl) propionamide, methyl iodide, benzene bromide, tetrabutylammonium iodide, diethyl trifluoroborate, phosphoric acid triester and the like.

As these reaction initiators, the battery itself is brought into a non-recoverable state by initiating polymerization and solidification preferably at 120 ° C. or higher against temperature rise due to overdischarge or overcharge or temperature rise due to an external environment. The amount and substance of these additions are selected so as to stop the operation of. It is more preferably at least 100 ° C, more preferably at least 80 ° C. In particular, at 150 ° C
It is preferable that the material does not ignite by solidification by heating for a minute, and therefore, it is preferable to use a non-aqueous solvent which is thermally polymerized at 100 to 150 ° C. as an electrolytic solution. This reaction initiator is preferably 0.5 to 10% by weight, more preferably 1 to 5% by weight, based on the whole electrolyte.

In the present invention, it is preferable that at least one of the negative electrode and the positive electrode has a roughened surface having a metal layer, such as nickel plating, having a higher hardness than the base metal of the current collector.

In the present invention, it is preferable that at least one of the negative electrode active material and the positive electrode active material has graphite, and the graphite has 20% by weight or less of rhombohedral crystals and 80% by weight or more of hexagonal crystals.

In the present invention, a negative electrode having a negative electrode active material for absorbing and releasing lithium ions on the surface of a current collector made of a thin metal plate during charging and discharging, and a positive electrode having a positive electrode active material on the surface of a current collector consisting of a thin metal plate And a lithium ion battery comprising a lithium ion conductive non-aqueous electrolyte, wherein before forming each of the active materials on at least one current collector surface of the negative electrode and the positive electrode, the current collector surface After forming an oxide layer made of a whisker-like oxide, it is preferable to include a treatment for reducing and roughening the oxide layer.

Further, the current collector made of a metal sheet of at least one of the negative electrode and the positive electrode is processed to a desired thickness by cold rolling, and the processed surface is roughened as described above to form a surface. Preferably, the active material is formed.

That is, the deterioration of the battery characteristics due to the properties of the negative electrode current collector made of copper is due to a decrease in the adhesiveness between the negative electrode current collector and the negative electrode active material. By improving the adhesiveness, the battery characteristics can be improved. It is thought that we can plan. Therefore, in the present invention, it is preferable that the positive electrode current collector has a similar surface.

The positive and negative electrode active materials generally have a particle size of 100 μm.
m or less are preferred. The above object can be achieved by improving the adhesiveness between the current collector material aluminum or copper and the particles.

At the time of bonding the metal and the particles, at least a step of forming an oxide on the surface of the metal to which the particles are bonded, and a step of chemically or electrically treating all or all of the oxides It is effective that the treatment is performed by a step of reducing a part or a step of further performing nickel plating. The copper surface subjected to such treatment is in a roughened state as compared with before the treatment. Copper treated without nickel plating does not have the metallic luster of copper, and has a dark brown or black hue due to light scattering due to the roughened surface. As a method of bonding the particles to the copper having been subjected to the surface roughening treatment, there is a method of applying a mixture of the particles and the resin to the copper having the roughened surface and heating by pressure welding. Further, there is a method in which a slurry in which particles are kneaded with a solvent in which a resin is dissolved is applied and heated by pressure welding. In this case, the pressure welding and the heating may be performed separately before and after, or simultaneously, and in any case, the present invention is effective. The metal roughened by the surface treatment can improve the adhesiveness to the particles, but it is particularly preferable that the ratio of the substantial surface area to the apparent surface area is 2 or more. For example, in the case of a metal foil having a thickness of 20 μm and a width of 100 mm,
The apparent surface area is 20,000 mm ^{2 on} two surfaces. The apparent surface area both sides of the metal foil is S (mm ^2), roughened metal foil treated as described above also, the apparent surface area is S (mm ^2). Let the weight of the roughened metal foil be M (g). In addition, BET
The specific surface area of the roughened metal foil measured by the method is ρ (mm ² / g)
And At this time, the real surface area determined from the specific surface area is ρ × M (mm ² ). Therefore, the value of the actual surface area / apparent surface area is (ρ × M) / S.

The negative electrode current collector of the present invention preferably has a substantial surface area of 2 or more with respect to the apparent surface area, more preferably 3 or more.
The above is preferable, and 4 or more is preferable to obtain stable characteristics. The upper limit is preferably 30, more preferably 20 or less, especially 15
It is preferable to set the following. Current collector metal foil is 5-30μ
m, more preferably a thickness of 8 to 20 μm.

As the metal foil as the current collector, aluminum is used for the positive electrode and copper is used for the negative electrode. It is preferable to apply the positive and negative electrode active materials in a high form and form them by pressure molding. Although it may be annealed after rolling,
It is preferable to adjust the hardness of the surface by adjusting the annealing temperature in relation to the method of pressure molding.

The step of forming an oxide on the surface of the metal at least in advance, a step of chemically or electrically treating to reduce all or a part of the oxide, or more preferably a step of nickel plating By applying, using the treated metal foil as a positive or negative electrode current collector,
In a non-aqueous electrolyte secondary battery having improved adhesion to a positive electrode or a negative electrode active material, the positive electrode or the negative electrode active material hardly falls off or peels off during charge and discharge, and has good charge-discharge cycle characteristics.

In order to strengthen the surface of the base metal of the current collector, it is sufficient that the base metal is deformable with a metal harder than the base metal.
In particular, it is preferable to form a metal film harder than the base metal after roughening the surface of the metal foil by plating cobalt, nickel, or the like. This metal film is preferable in that it prevents flattening when forming under pressure during the formation of the positive and negative electrode active materials, thereby increasing the adhesion, and furthermore, increasing the corrosion resistance on the aluminum and copper surfaces. Its thickness is 0.
01 to 1 μm is preferred.

As the negative electrode active material, any particles capable of inserting and extracting lithium ions may be used. Graphites, amorphous carbons, pyrolytic carbons, cokes, carbon fibers, metallic lithium, lithium Alloys (Li-Al, Li-
Pb, etc.), inorganic compounds (carbides, oxides, nitrides, borides, halides, intermetallic compounds, etc.), and metal particle compounds such as aluminum and tin can be used.

Substances other than these metals have an average particle size of 5 to 3
0 μm is preferable, and particularly preferably 10 to 20 μm. Since small particles impair the properties, the minimum particle size is preferably 5 μm or more, and the maximum particle size is preferably 50 μm or less.
The metal powder is effective for increasing the conductivity of the film, and the average particle size is preferably 0.1 to 100 μm, more preferably 1 to 50 μm.
Graphite is preferably 20% by weight or less of rhombohedral crystals, particularly 5% by weight.
-15% by weight is preferred.

As a positive electrode active material, lithium cobalt oxide (Li _x CoO ₂ ), lithium nickel oxide (Li
_x NiO ₂ ), lithium manganese oxide (Li _x Mn)
_{2 O 4, Li x MnO 3} ), and lithium nickel cobalt oxide _{(Li x Ni y Co (1} -y) O 2) composite oxide or the like can be used. These materials preferably have an average particle size of 5 to 30 μm, and preferably have the same particle size as that of a metal other than the same metal as the negative electrode active material.

As the separator, a microporous polymer resin film of nylon, cellulose, nitrocellulose, polysulfone, polyacrylonitrile, polyvinylidene fluoride, polypropylene, polyethylene, or polyolefin is used.

As the electrolyte, lithium hexafluorophosphate
(LiPF ₆ ), LiBF ₄ , LiClO _{4 and the} like are used. These compounds are preferably used in an amount of 0.2 to 5 mol, more preferably 0.5 to 3 mol, per liter of the electrolytic solution.

As the conductive material used as the negative electrode and the positive electrode active material, flaky graphite, massive amorphous carbon and massive graphite are preferable, having an average particle size of 10 to 30 μm or less, a specific surface area of ² to 300 m ² / g, It is more preferably 15 to 280 m ² / g, and it is preferable to use short carbon fibers having a diameter of 5 to 10 μm and a length of 10 to 30 μm. In particular, massive graphite has high adhesion.

The negative electrode and the positive electrode active material have a resin of 2 to 2 times.
It contains 0% by weight and is bonded to the current collector surface by this resin. Polyvinylidene fluoride is used as the resin. In the nonaqueous electrolyte secondary battery to which the present invention is applied, the surface of the negative electrode current collector is appropriately roughened, and the anchor effect is large as compared with the negative electrode current collector having a smooth surface. Adhesive strength with the negative electrode mixture can be improved. As a result, it is possible to prevent the negative electrode mixture from peeling or falling due to expansion and contraction of the negative electrode active material during charge and discharge, and to improve the charge and discharge cycle characteristics of the nonaqueous electrolyte secondary battery. .

The lithium secondary battery of the present invention has a shape such as a cylindrical type, a coin type, and a rectangular type.
Notebook PCs, notebook word processors, palmtop (pocket) PCs, mobile phones, PHS, mobile faxes, mobile printers, headphone stereos, video cameras, mobile TVs, portable CDs, portables MD, electric shaving machine, electronic guard, transceiver, electric tool, radio, tape recorder, digital camera, portable copier, portable game machine, electric car, hybrid car, vending machine, electric cart, load storage for load leveling system,
It can be used for home electric storage, distributed power storage system (built-in in stationary appliances), emergency power supply system, etc.

[0046]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is not limited to the following embodiments.

(Examples 1 to 9, Comparative Examples 1 and 2) FIG. 1 is a sectional view of a lithium secondary battery used in this example.

In Example 1, non-graphite carbon was used for the negative electrode active material layer 5, and polyvinylidene fluoride (hereinafter referred to as P) was used as a binder.
VDF), and a paste obtained by dissolving them in N-methylpyrrolidone (hereinafter abbreviated as NMP) was applied to a paste having a thickness of 20 μm.
The negative electrode current collector 6 made of copper foil was coated on both sides, and heated and pressed to obtain a negative electrode. The positive electrode active material layer 7 has L
Using iMn ₂ O ₄ , PVDF as a binder, amorphous carbon as a conductive aid, and a paste obtained by dissolving them in NMP on both surfaces of a positive electrode current collector 8 made of aluminum foil having a thickness of 20 μm. Coating, heating and pressing were performed to obtain a positive electrode.
A current collecting negative electrode current collecting tab 16 and a positive electrode current collecting tab 17 are attached to one end of the positive electrode and the negative electrode at equal intervals by welding, and wound as shown in FIG. Battery cover 15 with 10 and negative electrode terminal 11
After the battery was inserted into the battery can 14, an electrolytic solution was injected, and the battery lid 15 and the battery can 14 were caulked and sealed to produce a battery having an outer dimension of 54 mm in diameter and 200 mm in height. In Example 1, as shown in Table 1, a solution obtained by mixing propylene carbonate (hereinafter, described as PC), ethyl methyl carbonate (hereinafter, described as EMC) and 1,3-propylene carbonate at a volume ratio of 60:30:10 was used. An electrolyte was prepared by dissolving LiBF ₄ as a lithium salt at 1 mol / liter and further adding 5% by weight of iodine to this solution.
The amount of electrolyte injected was about 85 ml.

Similarly, as shown in Table 1, batteries of Examples 2 to 9 and Comparative Examples 1 and 2 were produced.

As the battery characteristics of the battery manufactured as described above, the first discharge capacity and the utilization factor of the discharge were set to 70% when the energizing current was set to 10 A, and after a continuous repetitive charge / discharge cycle test was performed 300 times. Was evaluated for discharge capacity. In addition, as a safety test, a burner heating test using a gas stove was performed because the risk of ignition of fire was the highest because the amount of electrolyte was large for large batteries. Table 1 shows the results.

[0051]

[Table 1]

As shown in Table 1, in the batteries of Comparative Examples 1 and 2 using the conventional electrolytic solution, the electrolytic solution erupted from the battery 4 to 5 minutes after ignition of the gas stove, and the burner fire ignited and burned. This combustion lasted about 20 minutes. On the other hand, Example batteries 1 to 9 using the electrolytic solution of the present invention having a self-solidifying action
In each case, the electrolyte solution solidified and did not ignite.

The conductivity of the electrolyte of Example 9 was 9 mS.
/ Cm. FIG. 2 shows the results of evaluating the reactivity of this electrolytic solution with a differential thermal analyzer (DSC). This electrolytic solution reacted at around 140 ° C. and showed heat generation. Since the sample after this test was solidified, it was confirmed that this electrolyte solution solidified at around 140 ° C.

According to this example, in the battery using the electrolyte of the present invention, the electrolyte could be solidified and the battery could be brought into a non-recoverable state without any substantial dimensional change in appearance.
The substantial dimensional change is an increase of about 0.1 mm in the diameter of the battery body when the temperature of the battery once returned to its original unused state is less than 0.5 mm.

Example 10 The lithium secondary battery of the present invention shown in FIG. 4 was similarly manufactured as follows. LiCoO ₂ as a positive electrode active material, 7 wt% of acetylene black as a conductive agent, and 5 wt% of polyvinylidene fluoride (PVDF) as a binder, and N-methyl-2-pyrrolidone were added thereto, followed by mixing. Was prepared.

Similarly, rhombohedral crystals 5 to 2 were used as negative electrode active materials.
Graphite powder having an arbitrary content of 0% by weight and 80% by weight or more of hexagonal crystals, and 10 parts of PVDF as a binder.
wt-%, and N-methyl-2-pyrrolidone was added thereto and mixed to prepare a slurry of the negative electrode mixture. The graphite powder has an average particle size of 25 μm and an amount of rhombohedral crystals of 285.
It was adjusted by changing the heating time at 0 ° C.

The positive electrode mixture was applied to both sides of a 25 μm-thick aluminum foil, and then vacuum dried at 120 ° C. for 1 hour. After vacuum drying, the electrode was pressure-molded by a roller press to a thickness of 195 μm. The applied amount of the mixture per unit area was 55 mg / cm ² , and was cut into a size of 40 mm in width and 285 mm in length to produce a positive electrode. However, the positive electrode mixture was not applied to both ends of the positive electrode at a length of 10 mm, and the aluminum foil was exposed. A positive electrode tab was pressure-bonded to one of these parts by ultrasonic bonding.

On the other hand, the negative electrode mixture was applied to both surfaces of a 10 μm-thick as-rolled copper foil which had been subjected to an oxidation treatment and a reduction treatment described later, and then vacuum dried at 120 ° C. for 1 hour. After vacuum drying, the electrode was pressure-molded by a roller press to a thickness of 175 μm. 25mg of mixture applied per unit area
/ Cm ² and cut out to a size of 40 mm in width and 290 mm in length to produce a negative electrode. Similarly to the positive electrode, the negative electrode mixture was not applied to both ends of the negative electrode at a length of 10 mm, and the copper foil was exposed, and a negative electrode tab was pressure-bonded to one of them by ultrasonic bonding.

As the separator, a microporous film made of polypropylene having a thickness of 25 μm and a width of 44 mm was used. A positive electrode, a separator, a negative electrode, and a separator were superposed in this order, and this was wound as shown in FIG. 2 to form an electrode group. This was inserted into a battery can, and a negative electrode tab was welded to the bottom of the can to provide a throttle portion for caulking the positive electrode lid. 1 mol of lithium hexafluorophosphate was added to a mixed solvent of ethylene carbonate, diethyl carbonate and 1.3 propylene carbonate having a volume ratio of 45:45:10.
l / l while dissolving the whole solution with 2% iodine.
After injecting the electrolyte solution added by weight% into the battery can, the positive electrode tab was welded to the positive electrode lid, and then the positive electrode lid was crimped to produce a battery. The battery can 14 is made of SUS304, 316 austenitic stainless steel.

Using this battery, a charge / discharge current of 300 m
A, charge / discharge was repeated with the charge / discharge end voltage being 4.2 V and 2.8 V, respectively. The charge current was changed in the range of 300 mA to 900 mA, and rapid charge and discharge were performed. The discharge amount of this battery was 880 mAh. The charge / discharge capacity during rapid charge / discharge was 800 mAh or more, and the discharge capacity was 800 mAh or more even after 300 cycles.

A as-rolled tough pitch copper plate having a thickness of 0.1 mm and a size of 100 mm was used. According to the following steps, a reduction treatment after the oxidation treatment described below was performed on the surface of the copper plate.

First, the above copper plate was degreased at a liquid temperature of 55 ° C. at 50 g / l of C4000, and then washed with water. Next, ammonium disulfate [(NH ₄ ) ₂ S ₂ O ₄ ] 200 g / l sulfuric acid (H ₂ SO ₄ ) 5 ml / l The solution was treated at a liquid temperature of 30 ° C. and washed with water. Next, the product was pickled with sulfuric acid (H ₂ SO ₄ ) 3 ml / l and then washed with water. Next, sodium chlorate (NaCl ₃ O) 109 g / l sodium phosphate (Na ₃ PO ₄ .12H ₂ O) 30 g / l sodium hydroxide (NaOH) 15 g / l Copper oxide was formed on the surface.
After washing with water, dimethylamine borane [(CH ₃ ) ₂ NHBH ₃ ] 6 g / l sodium hydroxide (NaOH) 5 g / l was subjected to a reduction treatment at a liquid temperature of 45 ° C. Thereafter, the substrate was washed with pure water and dried with hot air. Each of these treatments was performed by dipping in a stirred solution for a predetermined time.

C4000 removes stains on the surface of the copper plate after rolling. NaOH is added to adjust the pH to 11 to 13, and a surfactant is further added. Ammonium disulfate dissolves the copper surface and sulfuric acid dissolves the copper oxide.

The state of the surface treatment includes the time, temperature,
Although it can be controlled by the solution concentration, here, copper plates having various treatment times were prepared. The processing time is 60,12
0,300 sec. As a result of observing the surface of the copper plate after the treatment with a scanning electron microscope, it was confirmed that the longer the oxidation treatment time was, the more the surface became rough. Further, the specific surface area was measured by the BET method using Kr gas to determine the actual surface area. Table 2 shows the ratio of the substantial surface to the apparent surface area of the copper plate. Here, No. 1 is a comparative example, which is a rolled copper plate that is not subjected to the above-described series of processing.

[0065]

[Table 2]

As shown in Table 2, the surface roughening of the copper plate progresses as the oxidation treatment time increases. The reason why the actual surface / apparent surface area is 1 or less in Comparative Example 1 is due to a specific surface area measurement error by the BET method used in this example. Therefore,
Each of the values of the actual surface area / apparent surface area of each sample includes such an error.

The real surface area increases almost linearly with an increase in the oxidation time, and the real surface area ratio becomes 3 or more in about 1 minute, and slightly increases in 200 seconds or more.

In this example, as a result of observing the surface subjected to the oxidation treatment for 300 seconds with an electron microscope, the diameter was 1 to 30 nm and the length was 5 mm.
A whisker-like oxide of 0-200 nm was formed. Also,
Subsequent reduction treatment causes the surface to have a diameter of 5-20 nm.
The rod-like coatings having a length of 100 to 500 nm were formed on the surfaces thereof, slightly entangled with each other. In particular, the diameter and length vary depending on the processing time.

Next, the adhesion between the copper plate and the particles will be described. As particles, flaky graphite having an average particle size of about 25 μm,
Lumpy amorphous carbon having an average particle size of about 15 μm and aluminum powder having an average particle size of 30 μm were used. These particles were kneaded with an N-methylpyrrolidone solution in which polyvinylidene fluoride was dissolved to form a slurry. This slurry was applied to a copper plate shown in Table 1. At this time, each particle in the slurry was mixed with polyvinylidene fluoride at a weight ratio of particle: polyvinylidene fluoride = 90: 10. After the copper plate coated with the above slurry is dried in the air, the copper plate is pressed at a pressure of 500 kg / cm ² to increase the density of the film,
Further, it was vacuum dried at 120 ° C. The particle-adhered copper plate produced in the above procedure was cut so that the particle-adhered area was 4 cm ^2, and a commercially available adhesive tape was applied so as to cover the entire surface of the particle-adhered portion. The adhesion between the copper plate and the particles was evaluated based on the ratio of the particles that peeled off when the pressure-sensitive adhesive tape was peeled off. Table 3 shows the results.
Shown in

[0070]

[Table 3]

In Table 3, the smaller the ratio of particles peeled off when the adhesive tape is peeled off, the better the adhesion between the copper plate and the particles. Thereby, compared with the as-rolled copper plate, the copper plate subjected to the surface roughening treatment in the oxidation and reduction steps had better adhesion to the particles. In addition, although there is a difference in adhesion depending on the type and particle size of the particles, in the copper plate with a roughened surface,
The adhesion to the particles was improved as compared with the as-rolled copper plate.

That is, the relationship between the ratio of the exfoliated particles and the ratio (substantial surface area / apparent surface area) is that the exfoliation rate is substantially saturated when the flaky graphite and Al powder have a substantial surface area ratio of 2 or more, and the former is 3%.
5% or less, and the latter less than 15%. The amorphous carbon had a substantial surface area of 4 or more and a peeling rate of 25% or less.

In this example, a burner heating test using a gas stove was carried out in the same manner as described above, but there was no violent ejection of electrolysis, no solidification, and no ignition. Furthermore, there was no substantial dimensional change.

(Embodiment 11) FIG. 5 is a sectional view of a coin-type battery according to the present invention. The current collector, the positive electrode mixture, and the negative electrode mixture used for the positive electrode and the negative electrode of this example were manufactured in the same manner as in Example 10. The negative electrode has a diameter of 14.5 mm and the thickness of the electrode is 0.4 m.
m pellets. The positive electrode had a diameter of 14.5 mm and the thickness of the electrode was 0.9 mm. As shown in FIG. 5, a positive electrode current collector was previously attached to the inner bottom surface by welding, and the positive electrode was pressure-bonded to a positive electrode can on which a gasket made of insulating packing was placed. Next, a microporous polypropylene separator was placed under the separator, and 1 mol / l was added to a mixed solvent of ethylene carbonate, propylene carbonate, diethyl carbonate, and 1,3 propylene cardinate at a volume ratio of 30: 15: 45: 10. Of LiPF ₆ is dissolved and iodine is
Impregnated with electrolyte solution added by weight%. On the other hand, a negative electrode current collector is welded to the inner surface of the negative electrode can 4, and the negative electrode is pressed on the negative electrode current collector. Next, the negative electrode is placed on the separator, and the positive electrode can and the negative electrode can are caulked with a gasket interposed therebetween, thereby producing a coin-type battery. In this example, a burner heating test was performed in the same manner as described above, and the result was the same as described above. The dimensional change was measured at the top and bottom, but the actual change was about 0.05m
m or less.

Example 12 The positive electrode active material used in this example was a LiCoO ₂ powder having an average particle size of 10 μm.
This positive electrode active material and natural graphite and polyvinylidene fluoride
-Methyl-2-pyrrolidone solution was added and kneaded sufficiently to obtain a positive electrode slurry. LiCoO ₂ , natural graphite,
The mixing ratio of polyvinylidene fluoride is 90: 6:
And 4. The slurry is prepared by the doctor blade method.
It was applied to the surface of a positive electrode current collector made of an aluminum foil having a thickness of 20 μm. The positive electrode has a rectangular shape with a height of 70 mm and a width of 120 mm. This positive electrode was dried at 100 ° C. for 2 hours.

The negative electrode was manufactured by the following method. Average particle size 5
μm of natural graphite powder and polyvinylidene fluoride were mixed at a weight ratio of 90:10, and 1-methyl-2-
Pyrrolidone was added and kneaded well to prepare a negative electrode slurry. This slurry was applied to the surface of a negative electrode current collector composed of as-rolled copper foil having a thickness of 10 μm and subjected to a surface treatment under the same conditions as in No. 4 of Example 1 by a doctor blade method. The negative electrode has a rectangular shape with a height of 70 mm and a width of 120 mm. This negative electrode was dried at 100 ° C. for 2 hours.

FIG. 6 is a sectional view of the prismatic lithium secondary battery of the present invention. The external dimensions of the battery are 100 mm high and 13 width wide.
0 mm and depth 30 mm. An electrode group in which positive electrodes 31 and negative electrodes 32 inserted in a bag-shaped separator 33 were alternately stacked was inserted into an aluminum battery can 34. Positive electrode lead 35 and negative electrode lead 37 welded on top of each electrode
Were connected to the positive terminal 38 and the negative terminal 39, respectively.
The positive terminal 38 and the negative terminal 39 are inserted into the battery cover 41 via a packing 40 made of polypropylene. The external cable and the battery can be connected by the nut 20 attached to the positive terminal 38 and the negative terminal 39. Battery cover 4
1, when the pressure inside the battery reaches 4-7 atm,
A safety valve for releasing gas accumulated inside the battery and an electrolyte injection port were installed. Safety valve is gas outlet 4
2, an O-ring 43 and a sealing bolt 44. The liquid inlet comprises an inlet 45, an O-ring 46, and a sealing bolt 47. After laser welding the battery can 34 and the battery lid 41,
An electrolytic solution was introduced from the inlet 45, and the inlet 45 was sealed with a sealing bolt 47 to complete a lithium secondary battery. The electrolyte used contained 1 mol of lithium hexafluorophosphate (LiPF ₆ ) in 1 liter of a mixed solvent of ethylene carbonate, dimethyl carbonate and 1,3 propylene carbonate in a volume ratio of 45:45:10. Solution. 5% by weight of iodine was added to this electrolyte.

The electrochemical energy of the battery can be taken out from the positive electrode terminal and the negative electrode terminal and stored by recharging. The average discharge voltage of this battery is 3.
7V, rated capacity is 27 Ah, 100 Wh.

The lid 11 of the above-described prismatic lithium secondary battery 21
Were assembled in a row so that the sides having a height of 100 mm and a width of 130 mm face each other, and an eight-series connected battery shown in FIG. 7 was assembled.

In the present invention, the thickness of the spacer is limited to less than 10% of the battery thickness in order to keep the reduction rate of the volume energy density of the battery pack by using the spacer to about 10%. Since the thickness of the battery 21 is 30 mm,
Two spacers 22 made of polytetrafluoroethylene having a length of 0 mm, a width of 10 mm, and a length of 100 mm were inserted between the battery facing surfaces along the height direction of the battery 21. The stainless steel metal plate 23 attached to the side surface and the front and rear of the assembled battery and the polytetrafluoroethylene fixing part 28 were fixed with bolts 29, and the rectangular lithium secondary battery 21 was tightened so that pressure was applied inward. . To quickly dissipate the heat from the battery to the outside, a rib-shaped protrusion was formed on the stainless steel metal plate 23. The positive terminal and the negative terminal of each prismatic lithium secondary battery 21 are connected by a current cable so that all the batteries are connected in series, and the positive terminal 24 and the negative terminal 2 of the assembled battery are connected.
5 was connected. Further, the positive terminal and the negative terminal of each battery 21 are connected to a control circuit board 26 via a positive voltage input cable and a negative voltage input cable, respectively, so that the voltage and current of each battery 21 are controlled for charging and discharging of the assembled battery. Was measured. The control circuit board 26 is equipped with a microcomputer, and has a function of stopping charging / discharging of the battery pack when at least one of the voltage and current of at least one battery 21 is out of the set range. The control circuit board of the present invention uses a printed circuit board made of an epoxy resin to which glass fiber and 1% hexabromobenzene are added, and circuit elements are connected by using a wiring cable covered with polytetrafluoroethylene. It is a flame-retardant substrate with enhanced properties. A thermocouple 43 was attached to the side of the fourth battery from the battery at the end, a temperature signal was sent to the control circuit board 26, and charging and discharging were stopped when the battery temperature exceeded a set temperature. In this embodiment, the control circuit board 26
The shield plate 27 was inserted between the control circuit board 26 and the battery 21 so that the electrolyte discharged from the gas discharge port 42 did not adhere to the control circuit board 26. The average discharge voltage of the battery pack of this embodiment is 29.6.
V, rated capacity 27 Ah, 800 Wh. The assembled battery of this embodiment is denoted by B1. Since the battery pack of the present invention does not require an outer container, it is possible to directly cool the prismatic lithium secondary battery 21 with outside air, and to reduce the temperature rise of the battery during rapid charging or discharging at a high load rate. Can be reduced.

In the above description, the electrode group is a stacked type using strip electrodes. However, a similar assembled battery can be formed even when the electrode group is a flat and oblong wound type. Also, a burner heating test was performed, but the electrolyte solidified as described above,
The dimensional change was substantially unchanged in appearance.

(Embodiment 13) FIG. 8 is a diagram showing a drive system configuration of an electric vehicle using the lithium secondary batteries described in Embodiments 1 to 12.

When a key switch is turned on and an accelerator pedal is depressed in the same manner as in a normal gasoline-powered vehicle, the torque or rotation of the electric motor is controlled in accordance with the accelerator pedal depression angle. When the accelerator is released, the regenerative brake corresponding to the engine brake is operated, and when the brake is depressed, the regenerative braking force is further increased. The shift lever signal switches the vehicle forward or backward, and the gear ratio is always constant. As a control method, I control using an induction motor
The GBT vector control inverter method was adopted, and the power supply voltage was set to 336 V from the IGBT withstand voltage. In this embodiment,
The output was set to a maximum output of 45 kW and a maximum torque of 176 Nm from the power performance (acceleration / hill-climbing performance) of the vehicle, and the rated output was set to 30 kW from the maximum speed specification. As main control items, fail-safe control is performed in addition to forward / reverse control of the vehicle and regenerative control.

Since the heat density is increased by reducing the size and weight of the electric motor, it is important to provide an efficient cooling structure. Since the temperature rise of the electric motor increases in a general air-cooled type, the water-cooled type is used in the same manner as a general engine. The cooling water channel was provided in an aluminum frame that covered the motor body, and the shape was optimized by temperature rise simulation. The cooling water flows in from a water supply port of a water channel of the frame, is discharged after absorbing heat of the motor body, and is cooled by a radiator in a circulation path. With such a water cooling structure, the cooling performance could be improved about three times as compared with the air cooling.

The inverter uses an IGBT as a power element, and generates a maximum of several kilowatts of heat at the maximum output. In addition, heat is also generated from surge absorbing resistors, filter capacitors, and the like, and it is necessary to keep these components below the allowable temperature and cool them efficiently. Particularly, the cooling of the IGBT is a problem, and the cooling method may be air cooling, water cooling, oil cooling, or the like. Here, a forced water cooling system that can be easily handled and efficiently cooled was used.

Lithium 2 as a power source in this embodiment
The protection circuit shown in the figure is formed in the next battery. The protection circuit protects the battery from overcharge and overdischarge.
The protection circuit comprises a balance compensation circuit for adjusting the cell voltage of each battery as shown in FIG. 9, and is provided for each battery. This balance compensation circuit is controlled by the microcomputer. In conventional lithium secondary batteries, since the electrolyte is flammable, a thermistor is provided in each battery to detect the temperature or pressure, and monitoring is performed by monitoring the temperature or pressure. Even if it does, the flame is solidified by heating before having a flash point at which the liquid does not burn into the liquid, so that special temperature or pressure monitoring is not required. Thereby, the number of safety mechanisms can be reduced as a protection circuit. As shown in FIG. 8, when overdischarge or overcharge is detected, the power supply can be automatically opened and closed.

Although this embodiment shows an example using an induction motor, the same applies to an electric vehicle using a permanent magnet type synchronous motor and a DC shunt motor as shown in FIG. It can be used. In the figure, INV
(Inverter: Inverter), IM (Induction Motor:
Induction motor), E (Encoder: encoder), SM (Sync)
hronus Motor: Synchronous motor), PS (Position Sense)
r: position detector), PWM (Pulse Width Modulation), DCM (DC Motor: DC motor), CH
(Chopper: chopper), N ^* : speed command, T ^* : torque command. In the figure, each paragraph shows a control method, a system configuration, and main control parameters. (Embodiment 14) FIG. 11 is a configuration diagram showing a nighttime power storage system using the lithium secondary batteries described in Embodiments 1 to 12. This power storage system example is 2000kW x 4h, cell capacity 1
000 Wh, and shows an example of 360 batteries connected in series and 24 columns connected in parallel. Also in this embodiment, it is necessary to protect the battery from overcharging and overdischarging as in Embodiment 36, and the protection circuit shown in FIG. 9 has a monitoring / balance compensation circuit. In this embodiment, the battery is protected in the same manner as described above. Although the present embodiment is aimed at storing a large amount of electric power, it is also effective for home air conditioners, electric water heaters and the like.

[0088]

According to the present invention, by using a self-solidifying non-aqueous electrolyte, the safety at the time of burning, which is of the greatest concern in large lithium secondary batteries, is greatly improved, and the safety is high. The remarkable effect of obtaining a large lithium secondary battery for home electric power storage and electric vehicles can be obtained.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a large-sized lithium secondary battery according to Examples 1 to 9.

FIG. 2 is an assembly view of a positive electrode, a negative electrode, and a separator of the lithium secondary battery of the present invention.

FIG. 3 is a diagram showing a temperature relationship between a sample temperature and a calorific value.

FIG. 4 is a sectional view of a lithium secondary battery of Example 10.

FIG. 5 is a sectional view of a coin-type lithium secondary battery of Example 11.

FIG. 6 is a sectional view of a prismatic lithium secondary battery of Example 12.

FIG. 7 is a perspective view of a battery pack according to a twelfth embodiment.

FIG. 8 is a drive system configuration diagram of an electric vehicle according to a thirteenth embodiment.

FIG. 9 is a protection circuit for a lithium secondary battery.

FIG. 10 is a configuration diagram of various drive control systems for an electric vehicle according to a thirteenth embodiment.

FIG. 11 is a configuration diagram of a power storage system according to a fourteenth embodiment.

[Explanation of symbols]

1, 15: battery lid, 2: gasket, 3, 13: insulating plate, 5: negative electrode active material layer, 6: negative electrode current collector, 7: positive electrode active material layer, 8: positive electrode current collector, 9: separator 10: Positive terminal, 11: Negative terminal, 12: Center pin, 14: Battery can, 16: Negative current collector tab, 17: Positive current collector tab.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tomoe Takamura 7-1-1, Omikacho, Hitachi City, Ibaraki Prefecture Within Hitachi Research Laboratory, Hitachi, Ltd. (72) Inventor Takao Iwayanagi 7-1, Omikamachi, Hitachi City, Ibaraki Prefecture No. 1 Inside the Hitachi Research Laboratory, Hitachi, Ltd.

Claims (14)

[Claims] 1. A lithium secondary battery comprising a negative electrode capable of storing and releasing lithium, a positive electrode capable of storing and releasing lithium, and a non-aqueous electrolyte, wherein the non-aqueous electrolyte is thermally reacted at a predetermined temperature. A lithium secondary battery, which is solidified. 2. The non-aqueous electrolyte according to claim 1, comprising a lithium salt and a non-aqueous solvent, wherein said non-aqueous solvent comprises a non-aqueous solvent capable of dissolving said lithium salt and a thermopolymerizable non-aqueous solvent. A lithium secondary battery characterized by the above-mentioned. 3. The non-aqueous solvent for thermal polymerization according to claim 2, wherein
A lithium secondary battery obtained by dissolving at least one of a 10- to 10-membered cyclic carbonate derivative. 4. The lithium secondary battery according to claim 2, wherein the non-aqueous solvent for thermal polymerization is obtained by dissolving at least one of diphenyl carbonate derivatives. 5. The non-aqueous solvent for thermal polymerization according to claim 2, wherein
A lithium secondary battery obtained by dissolving at least one of a to 11-membered sulfite derivative. 6. The non-aqueous electrolytic solution according to claim 1, wherein iodine, lithium iodide, lithium fluoride, lithium bromide, lithium chloride, tetrakis (4-fluoro) is used as a thermal reaction initiator. Sodium phenyl) borate, lithium tetrakis (4-fluorophenyl) borate, isoazobutylnitrile, 1,1'-azobis (cyclohexane-1
-Carbonitrile), 2,2'-azobis (2-methyl-N- (1,1-bis (hydroxymethyl) ethyl) propionamide, methyl iodide, benzene bromide, tetrabutylammonium iodide, trifluoride A lithium secondary battery characterized by dissolving at least one of diethyl borate and phosphoric acid triester. 7. The non-aqueous electrolytic solution contains a carbonate ester solvent.
The lithium secondary battery according to claim 1, wherein the lithium secondary battery contains 0% by volume or more. 8. In a lithium secondary battery having a negative electrode capable of inserting and extracting lithium, a positive electrode capable of inserting and extracting lithium, and a non-aqueous electrolyte, when overcharge, overdischarge, or abnormal temperature rise occurs, Lithium 2 characterized in that it stops in a non-return state without substantial dimensional change in appearance
Next battery. 9. A lithium secondary battery comprising a negative electrode capable of occluding and releasing lithium, a positive electrode capable of occluding and releasing lithium, and a non-aqueous electrolyte when overcharge, overdischarge, or abnormal temperature rise occurs. A lithium secondary battery which stops in a non-recovery state without a change in appearance due to generation of gas in the battery. 10. A lithium secondary battery comprising a negative electrode capable of inserting and extracting lithium, a positive electrode capable of inserting and extracting lithium, and a non-aqueous electrolyte when overcharge, overdischarge, or abnormal temperature rise occurs. A lithium secondary battery that stops in a non-recovery state without a change in appearance due to a change in pressure in the battery. 11. An electrolyte for a lithium secondary battery comprising a lithium salt and a non-aqueous solvent capable of dissolving the lithium salt, wherein the electrolyte is solidified by a thermal reaction at a predetermined temperature. 12. An electric device using the lithium secondary battery according to claim 1 as a power supply. 13. An electric device using a lithium secondary battery as a power supply, wherein the protection means against overcharge, overdischarge or abnormal temperature rise of the secondary battery is free from detection of temperature and pressure of the battery. Battery voltage or current detecting means and control means for opening and closing the power supply circuit based on the detected value, and when the abnormal condition occurs in the secondary battery itself, non-recovery without causing appearance damage An electric device wherein the operation of the battery is stopped in a state. 14. An electric device according to claim 12, wherein the electric device is used for an electric vehicle or an electric power storage device.