JPH11144734A - Lithium secondary battery and manufacture of lithium secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery superior in safety to firing and explosion, even in an overcharge or the use under a high-temperature environment by including a composite material consisting of an oxygen absorbing material, consisting of a metal oxide and a conductive agent in a positive electrode. SOLUTION: A positive electrode agent material and a binder are mixed to a conductive agent having an oxygen absorbing material consisting of a metal oxide fixed thereto. The mixed positive electrode mix is adhered to a positive electrode current collector by the use of an organic solvent. the resulting positive electrode current collector is dried to manufacture a positive electrode. A negative electrode is manufactured by mixing a negative electrode active material to a binder, adhering the mixed negative electrode mix to a negative electrode current collector by the use of an organic solvent, and drying the resulting current collector. As the oxygen absorber, a copper oxide with an oxidation number of 2 or 1 represented by CuO or Cu3 O having defects, or an iron oxide with an oxidation number of 2 or an average oxidation number of 8/3 represented by FeO or Fe3 O4 can be used. Further, a series of oxygen defective compounds such as SnO, SnO2 and the like with tin oxidation number of 2 or 4 may be used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a lithium secondary battery.

[0002]

2. Description of the Related Art A non-aqueous electrolyte secondary battery represented by a lithium secondary battery can obtain a higher energy density than a lead storage battery or a nickel-cadmium battery, so that a video camera, a portable camera, and a mobile phone that are required to be lightweight and compact. It is used in portable electronic devices such as telephones and notebook computers.

The active material used for the negative electrode of a lithium secondary battery includes lithium metal, a carbon material capable of storing lithium ions, and the like. On the other hand, the positive electrode active material includes lithium, cobalt, nickel or manganese. Composite oxides with transition metals such as these have been used.

[0004] In particular, a typical example of a lithium-manganese oxide is LiMn2O4 having a spinel structure described in Japanese Patent Publication No. 58-34414. In order to improve the cycle life of this positive electrode active material, aluminum (ex.
No. 41), iron (Japanese Patent Application Laid-Open No. 4-160758,
No. 5-129019), cobalt (described in JP-A-4-160758, described in JP-A-5-190919), nickel (described in JP-A-4-29019)
No. 160758, described in JP-A-5-29019), chromium (described in JP-A-4-160758), copper (described in JP-A-5-129019), zinc (described in JP-A-5-29019) , Magnesium (described in JP-A-5-129019), boron (JP-A 5-129019)
Lithium-manganese oxides in which a part of manganese atoms has been substituted by a dissimilar metal such as described in JP-A-29019) are disclosed.

Recently, lithium-iron oxide (described in JP-A-8-78019) and iron-molybdenum oxide (described in JP-A-7-176324, JP-A-7-31212) have recently been used as positive electrode active materials.
217) and iron halides (described in JP-A-9-22698).

[0006]

With the spread of portable electric equipment, there is a demand for a lithium secondary battery that can withstand longer use and has excellent load characteristics. On the other hand, there has been a move to lower the cost of batteries, and replaced lithium cobalt oxide, which was conventionally used as a positive electrode active material, with a low-cost, resource-rich lithium-manganese oxide represented by LiMn2O4. Lithium secondary batteries are commercialized
(Described in Journal of Power Sources, Vol. 54, pp. 143-145).

Further, LiFeO2 is used as a low-cost cathode material.
And other lithium-iron oxides (8th Inter
national Meeting on Lithium Batteries, II-B-67, 19
96, published in Nagoya).

[0008] As described above, the demand for lithium secondary batteries is expanding more and more, but since flammable organic electrolytes are used in lithium secondary batteries, high safety is desired for the batteries. For example, at the time of overcharging, or when the battery is thrown into a fire or abnormally heated due to direct sunlight, oxygen released from the positive electrode active material inside the battery causes an oxidative reaction of the solvent of the electrolytic solution to generate more heat. As a result, there is a risk that the lithium secondary battery may ignite or explode.

An object of the present invention is to provide a lithium secondary battery having excellent safety against ignition and explosion even when overcharged or used in a high-temperature environment.

[0010]

Means for Solving the Problems As a result of working on the above technical problems, the present inventors have found that at least one element selected from the group consisting of copper, iron, zinc, titanium, tin, vanadium, molybdenum and manganese is contained. By using a positive electrode composed of a composite material in which a metal oxide is fixed on the surface of a conductive agent and a positive electrode active material, it is possible to reduce the amount of oxygen generated from the positive electrode active material in a high-temperature environment, and to reduce the electrolyte. It has been discovered that the reaction between the contained electrolyte and the positive electrode active material can be suppressed.

In other words, in order to achieve the above object, the present invention provides a lithium secondary battery comprising a positive electrode, a negative electrode, and an electrolyte, wherein the positive electrode comprises an oxygen-absorbing substance made of a metal oxide and a conductive agent. And a positive electrode active material.

Another feature of the present invention is that, in a lithium secondary battery including a positive electrode, a negative electrode, and an electrolyte, the positive electrode includes a positive electrode current collector, and a positive electrode mixture adhered to the positive electrode current collector. Wherein the positive electrode mixture comprises a conductive agent to which an oxygen absorbing material made of a metal oxide is fixed, a positive electrode active material, and a binder.

Further, as another feature of the present invention, the oxygen absorbing material has a chemical formula of CuO _1-α , Cu ₂ O _1-β , Fe ₂ O _3-γ , Fe ₃
O _4-δ , FeO _1-ε , SnO _2-ζ , ZnO _1-η , TiO _2-θ , Ti ₂ O
_3-κ , TiO _1-λ , V ₂ O _5-ν , VO _2-ξ , VO _1-σ , MoO _2-τ , M
oO _3-υ , MnO _1-φ , MnO _2-χ , Mn ₂ O _3-ψ , where α = 0
~ 0.8, β = 0 ~ 0.8, γ = 0 ~ 0.8, δ = 0 ~ 0.8, ε = 0 ~
0.8, ζ = 0-1.8, η = 0-0.8, θ = 0-0.8, κ = 0-0.
8, λ = 0 to 0.8, ν = 0 to 2.8, ξ = 0 to 0.8, σ = 0 to 0.
8, τ = 0 to 1.8, υ = 0 to 0.8, φ = 0 to 0.8, χ = 0 to 1.
8, ψ = 0 to 0.8, at least one kind of metal oxide.

Another feature of the present invention is that, in the method for manufacturing a lithium secondary battery comprising a positive electrode, a negative electrode, and an electrolyte, the positive electrode comprises a conductive agent having an oxygen absorbing material made of a metal oxide fixed thereon. A positive electrode active material and a binder are mixed, the mixed positive electrode mixture is attached to a positive electrode current collector using an organic solvent, and the attached positive electrode current collector is dried to produce a positive electrode mixture.
The negative electrode is produced by mixing a negative electrode active material and a binder, attaching the mixed negative electrode mixture to a negative electrode current collector using an organic solvent, and drying the attached negative electrode current collector. .

[0015] The individual solutions will be described in detail below. As the positive electrode active material used for the lithium secondary battery, there are many materials made of cobalt, nickel, manganese, and a composite oxide of iron and lithium. It is known that when these positive electrode active materials are heated, the oxygen elimination reaction proceeds from about 200 ° C (37th Battery Symposium, 1A11, 1996, Tokyo).

When the temperature of the lithium secondary battery rises to the oxygen desorption temperature, oxygen is generated from the positive electrode active material, and the oxygen oxidizes the solvent in the electrolyte by a combustion reaction, generating a large amount of heat inside the battery. , Battery ignition, explosion.
Therefore, by using an oxygen-absorbing substance capable of absorbing oxygen near the temperature at which oxygen is desorbed from the positive electrode active material for the positive electrode,
It is possible to suppress the oxidation reaction of the electrolyte solvent.

As materials for the oxygen-absorbing substance satisfying such requirements, CuO _1-α , Cu ₂ O _1-β , Fe ₂ O
_3-γ , Fe ₃ O _4-δ , FeO _1-ε , SnO _2-ζ , ZnO _1-η , Ti
O _2-θ , Ti ₂ O _3-κ , TiO _1-λ , V ₂ O _5-ν , VO _2-ξ , V
O _1-σ , MoO _2-τ , MoO _3-υ , MnO _1-φ , MnO _2-χ , Mn ₂ O
_3-ψ , where α = 0-0.8, β = 0-0.8, γ = 0-0.8,
δ = 0-0.8, ε = 0-0.8, ζ = 0-1.8, η = 0-0.8, θ
= 0 to 0.8, κ = 0 to 0.8, λ = 0 to 0.8, ν = 0 to 2.8, ξ =
0-0.8, σ = 0-0.8, τ = 0-1.8, υ = 0-0.8, φ = 0
Metal oxides represented by -0.8, χ = 0-1.8, ψ = 0-0.8.

For example, as a specific example of a copper-based oxygen absorber, an oxidation number of 2 represented by CuO and Cu ₂ O having oxygen defects is shown.
There is a monovalent or monovalent copper oxide or its oxygen deficient compound. Other iron-based oxygen scavengers include iron oxides having a divalent oxidation number represented by FeO and Fe ₃ O ₄ or an average oxidation number of 8/3,
Alternatively, a series of oxygen-deficient compounds of FeO, Fe ₃ O ₄ , and tin-based oxygen scavengers having a divalent or tetravalent tin oxidation of SnO or SnO
₂ and their oxygen-deficient compounds, and zinc-based oxygen scavengers, it is possible to use oxygen-deficient compounds of ZnO.

Further, as an example of a titanium-based oxygen scavenger, Ti
It is possible to use titanium oxide having a bivalent or trivalent oxidation number represented by O and Ti ₂ O ₃ and TiO ₂ , TiO, and Ti ₂ O ₃ having oxygen defects. Examples of vanadium-based oxygen scavengers include divalent to tetravalent oxides, ie, VO, V ₂ O ₃ ,
VO ₂ and their partial oxides can be used.

When these oxides are fixed on the surface of the conductive agent, when the battery is overcharged or left at a high temperature, the oxygen absorbing material changes to an oxide having a higher oxidation number, thereby absorbing the oxygen of the positive electrode active material. I found something.

The above-mentioned oxides are listed as examples of the oxygen-absorbing substance that can be used in the present invention. However, the scope of the present invention is not limited to this, and any metal oxide that can absorb oxygen can be used. can do.

Next, a method for synthesizing an oxygen absorbing substance, that is, an oxygen absorbing agent will be described. The raw materials of copper, iron, tin, zinc, titanium, and vanadium are their metal salts. Listed usable metal salts or oxides are CuCl, Cu (CH ₃ CO
O) ₂ , Fe (NO ₃ ) ₃ , SnCl ₂ , ZnNO ₃ , ZnCl ₂ , TiCl ₄ , V ₂ O ₃ and the like. Titanium salts, isopropyl alkoxy titanium _{(Ti (iC 3 H 7 O} ) 4), ethyl alkoxy titanium (Ti (C ₂ H _{5 5}
O) ₄ ) and other alkoxy compounds, TiCl ₄ , Ti (NO ₃ ) ₄ and the like. SnCl ₂ , SnCl ₄ , Sn (CH ₃ COO) ₂ , Sn (NO ₃ )
₂ and Sn (NO ₃ ) ₄ .

These metal salts are not limited to the above-mentioned metal salts and may be at least one of copper, iron, zinc, titanium, tin and vanadium, as long as they are decomposed by heat treatment and converted into metal oxides. May be used. Further, by partially reducing an oxide powder of copper, iron, zinc, titanium, tin, and vanadium or a mixed powder thereof in a hydrogen atmosphere, a partially reduced metal oxide is used as an oxygen absorbing material. It becomes possible.

In order for the synthesized oxygen absorbing material to be contained in the positive electrode, the oxygen absorbing material is directly applied to a carbonaceous conductive agent,
There is a method of mixing with a positive electrode active material and a binder. According to this method, a disadvantage that a binder and a conductive agent are required more than in the case where no oxygen absorbing material is added in order to secure electron conductivity between the positive electrode active material particles was observed.

When an oxygen-absorbing material is previously attached to the positive electrode active material by a powder impact method such as mechanical fusion, an extra binder is not required, but lithium insertion / desorption from the positive electrode active material is performed by the oxygen absorbing material. It was found that the reaction was inhibited and sufficient charge / discharge characteristics could not be obtained.

Then, the present inventors have conducted intensive studies, and as a result, have found a technique for fixing an oxygen absorbing substance to the surface of a conductive agent, and have reached the present invention.

The simplest method for fixing the oxygen absorbent to the conductive agent is a method in which the conductive agent and the oxygen absorbing substance are kneaded with a solvent or the like, and then dried and fixed. Also,
By adding a small amount of a surfactant or a high molecular binder such as polyvinylidene fluoride, Teflon, ethylene-butadiene rubber, or polyethylene oxide during kneading,
The adhesion between the oxygen absorbing substance and the conductive agent can be improved.

It is also effective to use a mechanical fusion method and fix the oxygen absorbing substance to the conductive agent by mechanical impact. In the present invention, the fixing method by the mechanical fusion method was the most effective. In order to adopt this method, it is desirable that the shapes of the oxygen absorbing substance and the conductive agent are as spherical as possible, and in order to increase the effect of mechanical shock, the particle size of the oxygen absorbing substance and the particle size of the conductive agent are increased. It is desirable that the difference be 1:10 or more.

Further, in order for the oxygen absorbing material to absorb oxygen released from the positive electrode active material, the particle size of the oxygen absorbing material is 50 μm.
It is desirable that the thickness be as small as possible and be as small as possible. The optimal particle size is between 0.1 and 1 μm.

When carbon powder of 10 μm or less is used as the conductive agent, the weight ratio of the carbon powder to the oxygen absorbing material is 100: 5.
The effect of scavenging oxygen from the positive electrode active material appears in the range of 100100: 200.

The conductive agent is generally graphite, mesophase carbon, carbon black, amorphous carbon, carbon fiber, vapor grown carbon fiber, pitch-based carbonaceous material, needle coke, petroleum coke, polyacrylonitrile-based carbon fiber. ,
Carbonaceous materials such as carbon black are available.

Further, since an oxygen scavenger can be fixed to a conductive polymer material composed of polyacene, polyparaphenylene, polyaniline, and polyacetylene to be used as a conductive agent, the type of the conductive agent is not limited in the present invention. Absent.

A positive electrode active material and a binder are mixed with the conductive agent to which the oxygen absorbing substance produced according to the present invention is fixed, and an organic solvent is added to the mixed positive electrode mixture and kneaded.
After the positive electrode mixture is attached to the current collector by a dipping method or a dipping method, the mixture is dried.

As an example of a positive electrode active material which can be used in the present invention and electrochemically inserts / desorbs lithium ions, LiMn ₂ O
_{4, LiMnO 3, LiMn 2 O} 3, LiMnO 2, Li4Mn 5 O 12, LiMn 2 -xMxO 2
(However, M = Co, Ni, Fe, Cr, Zn, Ta, x = 0.01-0.
2), Li ₂ Mn ₃ MO ₈ (where M = Fe, Co, Ni, Cu, Zn), Li _1-x
A _x Mn ₂ O ₄ (where A = Mg, B, Al, Fe, Co, Ni, Cr, Zn, C
a, x = 0.01 to 0.1), LiNi _1-x M _x O ₂ (where M = Co, Fe, G
a, x = 0.01-0.2), LiFeO ₂ , Fe ₂ (SO ₄ ) ₃ , LiCo _1-x M _x O
₂ (However, M = Ni, Fe, Mn, x = 0.01 to 0.2), LiNi1 _1-x M _x
O ₂ (where M = Mn, Fe, Co, Al, Ga, Ca, Mg, x = 0.01
To 0.2), Fe (MoO ₄ ) ₃ , FeF _{3 and the} like.

On the other hand, as the negative electrode active material, carbon to which lithium ions can be electrochemically inserted and desorbed, for example, graphite, mesophase carbon, amorphous carbon and expanded graphite can be used.

In addition, a metal or alloy capable of alloying with lithium or a material in which a metal is supported on the surface of carbon particles is used. For example, a metal or alloy selected from lithium, aluminum, tin, silicon, indium, gallium, and magnesium, or an alloy of the metal or the alloy and lithium can be used as the negative electrode active material.

Further, natural graphite, artificial graphite, carbon fiber,
Vapor-grown carbon fiber, pitch-based carbonaceous material, needle coke, petroleum coke, polyacrylonitrile-based carbon fiber, carbonaceous material such as carbon black, or 5
Amorphous carbon materials synthesized by pyrolysis of 6-membered or 6-membered cyclic hydrocarbons or cyclic oxygen-containing organic compounds, or polyacene, polyparaphenylene, polyaniline,
Conductive polymer material composed of polyacetylene or Sn
O, GeO ₂ , SnSiO ₃ , SnSi _0.5 O _1.5 , SnSi _0.7 Al _0.1 B _0.3 P _{0.2
O 3.5, SnSi 0.5 Al 0.3 B} 0.3 P 0.5 O 4.15 14 group is referred to as or oxide of a Group 15 element, or indium oxide, or zinc oxide, or Li ₃ FeN ₂ or Fe ₂ S,
It has been found that silicides represented by i ₃ , FeSi, FeSi ₂ , and Mg ₂ Si can also be used, and there is no particular limitation on the negative electrode active material.

As in the case of the positive electrode described above, a binder is mixed with the negative electrode active material, an organic solvent is added to the mixed negative electrode mixture, and the mixture is kneaded. The kneaded negative electrode mixture is adhered to the current collector, and then dried. I do. The positive electrode and the negative electrode produced in this way are molded under pressure,
Used as an electrode.

The negative electrode of the present invention can be applied to materials other than the above-mentioned negative electrode active materials. For example, a lithium metal sheet may be used.

After the positive electrode and the negative electrode are molded under pressure and cut, a separator made of polypropylene or polyethylene is interposed between the two electrodes.
Then, the electrodes are wound, and the electrode group is housed in a cylindrical or square battery can. Alternatively, the positive electrode and the negative electrode are laminated via a separator, and the electrode group is housed in a rectangular battery can. Then, the current collecting tab of the electrode group is welded to the battery lid or the battery can. After further injecting the electrolyte into the battery,
The battery is completed by welding the can and lid.

Solvents usable for the electrolyte include propylene carbonate, ethylene carbonate, butylene carbonate, vinylene carbonate, γ-butyrolactone, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, 1,2-dimethoxyethane, 2-methyltetrahydrofuran, Dimethyl sulfoxide, 1, 3-
Dioxolane, formamide, dimethylformamide,
From methyl propionate, ethyl propionate, phosphoric acid triester, trimethoxymethane, dioxolan, diethyl ether, sulfolane, 3-methyl-2-oxazolidinone, tetrahydrofuran, 1,2-diethoxyethane, chloroethylene carbonate, chloropropylene carbonate It is sufficient that at least one selected solvent is used.

The electrolyte dissolved in the solvent includes LiPF ₆ , LiBF ₄ , LiClO ₄ , LiCF ₃ SO ₃ , LiCF ₃ CO ₂ , LiAs
There are many kinds of lithium salts such as F ₆ , LiSbF ₆ , and lithium imide salts represented by lithium trifluoromethanesulfonimide. A non-aqueous electrolyte obtained by dissolving these salts in the above-mentioned solvent is used as an electrolyte for a battery.

Further, a solid electrolyte in which these electrolytes are held by a polymer of ethylene oxide, acrylonitrile, vinylidene fluoride, methyl methacrylate, hexafluoropropylene may be used instead of the non-aqueous electrolyte.

A gel electrolyte obtained by impregnating the above-mentioned non-aqueous electrolyte into a polymer of ethylene oxide, acrylonitrile, vinylidene fluoride, methyl methacrylate, and hexafluoropropylene may be used.

According to the present invention, by using a positive electrode containing a composite material of an oxygen absorbing material made of a metal oxide and a conductive agent and a positive electrode active material, oxygen generated from the positive electrode at a high temperature is captured. The oxidation reaction of the electrolyte can be reduced. As a result, ignition of the lithium secondary battery at high temperatures,
Explosion can be prevented.

[0046]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The gist of the present invention is that a novel material obtained by combining an oxygen absorbent and a conductive agent is applied to a non-aqueous electrolyte secondary battery. There are no restrictions on materials such as Hereinafter, the contents of the present invention will be described in detail using typical embodiments.

Embodiment 1 The positive electrode of this embodiment was produced by the method described below. A commercially available Fe (NO ₃ ) ₃ and graphite powder having an average particle size of 5 μm were kneaded with an equal volume mixed solvent of water and ethanol, and then sufficiently dried at 200 ° C. After drying, the powder was heat-treated in an atmosphere in which the oxygen partial pressure was adjusted to fix the iron oxide on the graphite powder. Further, the iron oxide was partially reduced by heat reduction in hydrogen.

As a result of analyzing the powder by X-ray photoelectron spectroscopy, it was confirmed that the oxidation state of the iron oxide was a mixed state of FeO, Fe ₂ O, and Fe ₃ O ₄ . Further, as a result of observing the surface of the synthesized powder with a scanning electron microscope, iron oxide having a particle size of 0.1 to 1 μm was fixed on the graphite powder surface. This powder is designated as A.

Similarly, graphite powder having an average particle size of 5 μm was added to CuCl,
SnCl ₂ , ZnCl ₂ , and V ₂ O ₅ were each mixed, and an equal volume mixed solvent of water and ethanol was added and kneaded sufficiently. The kneaded product was subjected to the same synthesis procedure as for powder A to prepare a composite powder in which each partial oxide of copper, tin, zinc, and vanadium was fixed on the surface of graphite powder. The synthesized powders are denoted as B, C, D, and E. As a result of analysis by X-ray photoelectron spectroscopy, when expressed by a composition formula on the surfaces of powders B, C, and D, respectively, Cu ₂ O _{0.5 to 0.7} , SnO _{0.5 to 0.8} , and ZnO _0.5 to _0.7
Confirmed that exists.

[0050] In addition, vanadium oxide on the surface of the powder E _{is, VO 0.5~0.8, V 2 O 3.6~3.8} , it was found that the mixed state of VO _{from 2.7 to 2.8.} Powders A, B, C, D, and E were each mixed with a positive electrode active material LiMn ₂ O ₄ powder having an average particle diameter of 20 μm in a mortar, and then polyvinylidene fluoride as a binder and 1-methyl- as an organic solvent. A 2-pyrrolidone solution was added and kneaded well to prepare five types of positive electrode slurries.

The positive electrode active material in the positive electrode slurry, the composite powder,
The weight composition ratio of polyvinylidene fluoride was 90: 6: 4. This positive electrode slurry was applied to the surface of a positive electrode current collector made of an aluminum foil having a thickness of 20 μm by a doctor blade method. This positive electrode current collector was dried at 100 ° C. for 2 hours to produce five types of positive electrodes.

The negative electrode of this embodiment was manufactured by the procedure described below. A negative electrode slurry was prepared by sufficiently kneading natural graphite powder having an average particle size of 5 μm, polyvinylidene fluoride and a 1-methyl-2-pyrrolidone solution. The weight ratio of graphite to polyvinylidene fluoride was 90:10. This negative electrode slurry was applied to the surface of a negative electrode current collector made of a copper foil having a thickness of 20 μm by a doctor blade method. 100 ° C
For 2 hours to prepare a negative electrode.

As the electrolytic solution used in the present embodiment, a non-aqueous electrolytic solution was prepared by dissolving 1 mol / liter of LiPF6 in a mixed solvent of ethylene carbonate and diethyl carbonate.

A cylindrical battery having a height of 65 mm and a diameter of 18 mm was assembled by combining the above five types of positive electrodes with a negative electrode.

FIG. 1 is a sectional view of the manufactured cylindrical battery. The positive electrode 1 and the negative electrode 2 are housed in a battery can 4 in a state of being spirally wound through a polyethylene microporous film 3 impregnated with the nonaqueous electrolyte prepared as described above. The positive electrode 1 is electrically connected to a battery lid 6 via a positive electrode lead 5.

The negative electrode 2 is welded to the bottom of the battery can 4 via a negative electrode lead 7. The battery cover 6 is provided with a safety valve 8 for releasing gas generated inside the battery. A gasket 9 is inserted between the battery can 4 and the battery lid 6, and the battery is sealed by swaging.

With such a configuration, it is possible to repeatedly charge and discharge the cylindrical battery. Cylindrical lithium secondary batteries using powders A, B, C, D, and E
2, B3, B4, and B5.

Embodiment 2 A cylindrical lithium secondary battery using a composite material of a titanium oxide and a conductive agent was manufactured by the procedure described below. After kneading commercially available Ti (iC ₃ H ₇ O) ₄ and graphite powder having an average particle size of 5 μm together with an equal volume mixed solvent of water and ethanol, a small amount of pure water is added to add Ti (iC ₃ H ₇ O). ) ₄
Was supported on graphite powder as Ti (OH) ₄ . 200 ℃
And dried sufficiently. After drying, the powder was heat-treated in an atmosphere in which the partial pressure of hydrogen was adjusted to fix the partially reduced titanium oxide on the graphite powder.

As a result of analyzing this powder by X-ray photoelectron spectroscopy, it was confirmed that the titanium oxide was in a mixed state of TiO _0.8-0.9 and TiO _2.6-2.7 . Further, as a result of observing the surface of the synthesized powder with a scanning electron microscope, titanium oxide having a particle size of 0.1 to 1 μm was fixed on the surface of the graphite powder. This powder is designated as F.

After mixing powder F with LiMn ₂ O ₄ powder having an average particle size of 20 μm in a mortar, polyvinylidene fluoride and 1-methyl-2
-Pyrrolidone solution was added and kneaded sufficiently, and a positive electrode was produced in the same manner as in Embodiment 1.

The cylindrical battery shown in FIG. 1 was assembled by combining the above positive electrode, the negative electrode of Embodiment 1 and the nonaqueous electrolyte. The cylindrical lithium secondary battery using the powder F is denoted by B6.

Embodiment 3 The positive electrode of this embodiment was manufactured by the method described below. The raw material powder of the oxygen-absorbing substance studied in the present embodiment is Cu ₂ O, Fe ₃ O ₄ , SnO,
There are six commercially available powders of ZnO, TiO, and V ₂ O ₃ .

After partial reduction of these powders in a stream of hydrogen,
The powder partially reduced by the pulverizer was pulverized in an inert gas to obtain a fine powder having an average particle diameter of 20 μm. After pre-mixing each of these fine powders and graphite powder with an average particle size of 2 μm,
Graphite particles were fixed on the surface of the metal oxide particles by a mechanofusion device.

The inside of the reaction vessel of the mechanofusion apparatus was set to an atmospheric nitrogen gas atmosphere. The mixing weight ratio between the metal oxide powder and the graphite powder was 10:90.

As described above, the composite powder of the oxygen-absorbing substance and the conductive agent synthesized by mechanofusion was used for G, H, I,
Expressed as J, K, L. To each of the composite powders, a polyvinylidene fluoride and a 1-methyl-2-pyrrolidone solution were added to the LiMn2O4 powder used in the first embodiment and sufficiently kneaded to obtain a positive electrode slurry.

The positive electrode active material in the positive electrode slurry, the composite powder,
The weight composition ratio of polyvinylidene fluoride was 90: 6: 4. This positive electrode slurry was applied to the surface of a positive electrode current collector made of an aluminum foil having a thickness of 20 μm by a doctor blade method. This positive electrode was dried at 100 ° C for 2 hours,
Six types of positive electrodes were produced.

The negative electrode and the electrolyte used had the same specifications as those of the first embodiment. Six types of cylindrical lithium secondary batteries having the structure shown in FIG. 1 were assembled using the six types of positive electrode, the negative electrode, and the non-aqueous electrolyte. Powder F, G, H, I, J,
B7, B8, B9, B10, B1
1 and B12.

(Comparative Example 1) LiMn ₂ O ₄ powder, graphite powder and polyvinylidene fluoride as binders having the same specifications used in Embodiment 1 were mixed at a weight ratio of 90: 6: 4.
Add 1-methyl-2-pyrrolidone solution as an organic solvent,
A well-kneaded positive electrode slurry was prepared by sufficiently kneading. Using this positive electrode slurry, a positive electrode was manufactured in the same manner as the positive electrode manufactured in Embodiment 1.

In the production of the negative electrode, the same natural graphite powder as in Embodiment 1 and polyvinylidene fluoride were used in a weight ratio of 9%.
The mixture was mixed at 0:10, a 1-methyl-2-pyrrolidone solution was further added, and the mixture was sufficiently kneaded to prepare a negative electrode slurry. Using this slurry, a negative electrode was manufactured in the same manner as the negative electrode manufactured in Embodiment 1.

The electrolyte used in the present embodiment has the same specifications as in the first embodiment. Using a positive electrode and a negative electrode using polyvinylidene fluoride as a binder, and a nonaqueous electrolyte, a cylindrical lithium secondary battery B13 having the same shape as that of Embodiment 1 was assembled.

Thirteen types of batteries B1, B2, B of Embodiment 1, Embodiment 2, Embodiment 3, and Comparative Example 1
3, B4, B5, B6, B7, B8, B9, B10, B
Constant current charging was performed for 11, B12, and B13 under the conditions of a charging current of 1 A and a charging time of 2 hours.
% Overcharge test. The number of batteries is 20 for each type.
The test environment temperature was room temperature.

Table 1 shows the test results.

[0073]

[Table 1]

Table 1 shows the ratio of the number of batteries that exploded or ignited to the number of batteries used in the overcharge test. In the case of the battery B13 of Comparative Example 1, 4 out of 10 batteries ignited,
It exploded, and the ignition and explosion rate was found to be as high as 40%.

The ignition by the batteries of Embodiments 1, 2 and 3
The explosion rate was 10% or less, and it was clarified that the risk of ignition and explosion could be significantly reduced by using the oxygen absorbing substance of the present invention.

Next, the first embodiment, the second embodiment,
13 types of batteries B1 and B of Embodiment 3 and Comparative Example 1
2, B3, B4, B5, B6, B7, B8, B9, B1
For 0, B11, B12, and B13, an explosion test of the battery was performed by throwing into a fire. After charging each battery to the rated capacity, a fire throw-in test was performed.

Table 2 shows the test results.

[0078]

[Table 2]

Table 2 shows the ratio of the number of batteries that caused an explosion to the number of batteries used in the fire test. Six out of ten batteries B13 of Comparative Example 1 exploded, and the explosion rate was 60
%.

The rate of occurrence of explosion in the batteries of Embodiments 1, 2, and 3 is 10% or less, and it is clear that the use of the oxygen-absorbing substance of the present invention can significantly reduce the risk of explosion due to being thrown into a fire. Became.

[Embodiment 4] The positive electrode of this embodiment was prepared by the method described below. The raw material powder of the oxygen absorbing material studied in the present embodiment is MoO ₂ , MoO ₃ , MnO, M
There are five commercially available powders of nO ₂ and Mn ₂ O ₃ .

After partial reduction of these powders in a stream of hydrogen,
The powder partially reduced by the pulverizer was pulverized in an inert gas to obtain a fine powder having an average particle diameter of 20 μm. After premixing each of these powders and graphite powder having an average particle size of 2 μm, the graphite particles were fixed on the surfaces of the metal oxide particles by a mechanofusion device.

The inside of the reaction vessel of the mechanofusion apparatus was set to an atmospheric nitrogen gas atmosphere. The mixing weight ratio between the metal oxide powder and the graphite powder was 10:90.

As described above, the composite powder of the oxygen-absorbing substance and the conductive agent synthesized by mechanofusion was mixed with M, N, O,
Notated as P and Q. As a result of examining the chemical composition of each composite powder by X-ray photoelectron spectroscopy, MoO ₂ , MoO, Mo ₂ O
A peak estimated to be ₃ was observed, and the average oxidation number of molybdenum was 0.8.

In the powder N, peaks estimated to be MoO ₂ , MoO, and Mo ₂ O ₃ were observed, and the average oxidation number of molybdenum was 3.5. Manganese of powder O, P, Q is Mn, MnO, MnO ₂ , Mn
_{It was in} a mixed state of ₂ O ₃ , and the average oxidation number of each manganese was 1.4, 3.1, 2.4.

A mixture of each of the powders M, N, O, P, and Q, the LiMn ₂ O ₄ powder used in Embodiment 1, and polyvinylidene fluoride was added to 1-methyl-2- A pyrrolidone solution was added thereto and kneaded sufficiently to obtain a positive electrode slurry.

The positive electrode active material in the positive electrode slurry, the composite powder,
The weight composition ratio of polyvinylidene fluoride was 90: 6: 4. This positive electrode slurry was applied to the surface of a positive electrode current collector made of an aluminum foil having a thickness of 20 μm by a doctor blade method. This positive electrode was dried at 100 ° C for 2 hours,
Five types of positive electrodes were produced.

The negative electrode and the electrolyte used had the same specifications as those of the first embodiment. Five types of cylindrical lithium secondary batteries having the structure shown in FIG. 1 were assembled using five types of positive electrodes, negative electrodes, and non-aqueous electrolytes.

As a result of performing the overcharge test described in Comparative Example 1 for these batteries, the explosion rate of the batteries of this embodiment was 10% or less. Therefore, it has been clarified that the use of the oxygen-absorbing substance of the present invention can significantly reduce the risk of explosion due to being thrown into a fire.

[Embodiment 5] Embodiments 1, 2,
LiBF ₄ , LiClO ₄ , LiCF ₃ S instead of LiPF ₆ used in ₃
Even when O ₃ , LiCF ₃ CO ₂ , LiAsF ₆ , LiSbF ₆ , and lithium trifluoromethanesulfonimide were used for the electrolyte, the explosion rate in the battery was less than 10%, and the same effect was obtained regardless of the type of electrolyte. .

Further, in place of the solvent used in Embodiment 1, propylene carbonate, ethylene carbonate, butylene carbonate, vinylene carbonate, γ
-Butyrolactone, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, 1,2-dimethoxyethane, 2-methyltetrahydrofuran, dimethyl sulfoxide, 1,3-dioxolane, formamide, dimethylformamide, methyl propionate, methyl propionate, phosphorus Acid triester, trimethoxymethane,
Comparative Example 1 was described using any of dioxolane, diethyl ether, sulfolane, 3-methyl-2-oxazolidinone, tetrahydrofuran, 1,2-diethoxyethane, chloroethylene carbonate, and chloropropylene carbonate as the electrolyte. As a result of conducting an explosion test, the explosion rate of the battery of the present invention was 10% or less.

[Embodiment 6] The cathode and anode prepared in Embodiment 1 and a polymer of ethylene oxide, acrylonitrile, vinylidene fluoride, methyl methacrylate, and hexafluoropropylene contain LiClO ₄ or LiBF _4. Using the solid electrolyte sheet having a thickness of 50 μm, a battery having the same shape as the lithium secondary battery of Embodiment 1 was produced.

Further, propylene carbonate, ethylene carbonate, butylene carbonate, vinylene carbonate, γ-butyrolactone, dimethyl carbonate, diethyl carbonate,
Methyl ethyl carbonate, 1,2-dimethoxyethane, 2
-Methyltetrahydrofuran, dimethylsulfoxide, 1,3-dioxolane, formamide, dimethylformamide, methyl propionate, ethyl propionate,
Gel electrolyte sheet impregnated with a small amount of phosphoric acid triester, trimethoxymethane, dioxolan, diethyl ether, sulfolane, 3-methyl-2-oxazolidinone, tetrahydrofuran, 1,2-diethoxyethane, chloroethylene carbonate, chloropropylene carbonate And a lithium secondary battery of the same shape as in Embodiment 1 was manufactured using the positive electrode and the negative electrode.

The result of the explosion test described in Comparative Example 1 was
The explosion rate of the battery of this embodiment was 10% or less.

[Embodiment 7] A composite powder in which a partial oxide of iron, copper, tin, zinc, vanadium, molybdenum, and manganese is fixed on a graphite surface in the same manner and using the same raw materials as in Embodiment 1. Was prepared. Next, Embodiment 1
LiMnO ₃ , LiMn ₂ O ₃ , LiMnO ₂ , L
_{i4Mn 5 O 12, LiMn 1.8 Co} 0.2 O 2, LiMn 1.8 Ni 0.2 O 2, LiMn 1.8 F
e _0.2 O ₂ , LiMn _1.8 Cr _0.2 O ₂ , LiMn _1.8 Zn _0.2 O ₂ , LiMn _1.8 Ta
_0.2 O ₂ , Li ₂ Mn ₃ FeO ₈ , Li ₂ Mn ₃ CoO ₈ , Li ₂ Mn ₃ NiO ₈ , Li ₂ Mn ₃ C
uO ₈ , Li ₂ Mn ₃ ZnO ₈ , Li _0.1 Mg _0.1 Mn ₂ O ₄ , Li _0.1 B _0.1 Mn ₂ O ₄ ,
Li _0.1 Al _0.1 Mn ₂ O ₄ , Li _0.1 Fe _0.1 Mn ₂ O ₄ , Li _0.1 Cr _0.1 Mn
₂ O ₄ , Li _0.1 Zn _0.1 Mn ₂ O ₄ , Li _0.1 Ca _0.1 Mn ₂ O ₄ , Li _0.1 Co _0.1 M
n ₂ O ₄ , Li _0.1 Ni _0.1 Mn ₂ O ₄ , LiNi _0.8 Co _0.2 O ₂ , LiNi _0.8 Fe
_0.2 O ₂ , LiNi _0.8 Ga _0.2 O ₂ , LiFeO ₂ , Fe ₂ (SO ₄ ) ₃ , LiCo _0.9 N
i _0.1 O ₂ , LiCo _0.9 Fe _0.1 O ₂ , LiCo _0.9 Mn _0.1 O ₂ , LiNi _0.8 Mn
_0.2 O ₂ , LiNi _0.8 Fe _0.2 O ₂ , LiNi _0.8 Co _0.2 O ₂ , LiNi _0.8 Al
_0.2 O ₂ , LiNi _0.8 Ga _0.2 O ₂ , LiNi _0.8 Ca _0.2 O ₂ , LiNi _0.8 Mg
One type was selected from _0.2 O ₂ , Fe (MoO ₄ ) ₃ , and FeF ₃ , and each of the powders was mixed with the above-described five types of composite powders and a binder to prepare a positive electrode.

A cylindrical lithium secondary battery was manufactured by combining these positive electrodes, a negative electrode having the same specifications as in the first embodiment, and an electrolytic solution. As a result of performing the same explosion test as in Embodiment 1, the explosion rate of the battery was 10% or less, and it was clarified that the present invention was also effective for positive electrode active materials other than Embodiment 1.

[Embodiment 8] A composite powder in which each partial oxide of iron, copper, tin, zinc, vanadium, molybdenum, and manganese used in Embodiment 1 is fixed on the graphite surface, LiMn2O4 and polyfluoride A positive electrode was produced from vinylidene in the same manner as in Embodiment 1. Next, a lithium metal negative electrode or a negative electrode prepared from aluminum, tin, silicon, indium, gallium, and magnesium powder having a particle size of 1 to 50 μm, carbon and polyvinylidene fluoride, and each of the above positive electrodes were combined. A battery having the same specifications as in Embodiment 1 was manufactured.

Further, artificial graphite having an average particle diameter of 10 μm, carbon fibers having an average diameter of 1 μm and a length of 5 to 20 μm, and vapor-grown carbon fibers and polyvinylidene fluoride were mixed to form the same composition as in the first embodiment. A negative electrode was manufactured.

Carbon powder synthesized by using petroleum pitch-based carbon, needle coke, petroleum coke, and polyacrylonitrile as raw materials and graphitizing them at a high temperature, and acetylene having a weight composition of 90:10 by weight on the carbon powder. A negative electrode was similarly prepared using a mixed carbon powder mixed with black.

An amorphous carbon material obtained by heat-treating fururyl alcohol and carbonized, a conductive polymer material composed of polyacene, polyparaphenylene, polyaniline, polyacetylene, or SnO, GeO ₂ , SnSiO ₃ , SnSi
_0.5 O _1.5 , SnSi _0.7 Al _0.1 B _0.3 P _0.2 O _3.5 , SnSi _0.5 Al _0.3 B
An oxide of a Group 14 or Group 15 element denoted as _0.3 P _0.5 O _4.15 , or In ₂ O ₃ , or ZnO ₂ , or Li ₃ FeN ₂ ,
Alternatively, each of the silicides represented by Fe ₂ Si ₃ , FeSi, FeSi ₂ , and Mg ₂ Si was mixed with polyvinylidene fluoride, and a negative electrode was produced in the same manner as in Embodiment 1.

A cylindrical lithium secondary battery was manufactured by combining these negative electrodes, a positive electrode having the same specifications as in the first embodiment, and an electrolytic solution. As a result of performing the same explosion test as in Comparative Example 1, the rate of occurrence of the explosion of the battery was 10% or less, and it was clarified that the present invention was also effective for positive electrode active materials other than Embodiment 1.

[Embodiment 9] FIG. 2 shows an example of a prismatic lithium secondary battery using the oxygen absorbing material of the present invention. The type of material used for the positive electrode containing powder A, the type of material used for the negative electrode, the type of material used for the electrolytic solution, and the manufacturing process of the electrode are the same as those of the battery B1 of the first embodiment.
The strip-shaped positive electrode 1 containing the oxygen-absorbing substance of the present invention comprises:
It is inserted into a bag-shaped separator 3 and alternately stacked with the strip-shaped negative electrodes 2.

A positive electrode lead 5 and a negative electrode lead 7 are welded to the upper part of each electrode, and are connected to external terminals 11 and 12 on the bottom surface of the lid 6. The lid 6 is provided with a safety valve 8 for releasing the pressure inside the battery. After the battery can 4 and the lid 6 are laser-welded, an electrolyte is introduced from the liquid inlet 10 and the liquid inlet 1
0 is welded to seal the battery.

FIG. 3 shows an example of a battery pack as an assembled battery on which the eight rectangular lithium secondary batteries shown in FIG. 2 are mounted. The battery pack 13 was assembled by connecting the used eight rectangular lithium secondary batteries in four series and two parallel.

The outer dimensions of the battery pack 13 are a height of 34 mm,
It is 140 mm wide and 58 mm deep. The control panel 14 controls the charging / discharging current of each unit cell 15 and connects to a device or a charger using the positive external terminal 16, the negative external terminal 17, and the common terminal 18. The battery pack 13 using the eight batteries of the present invention had an average discharge of 15.2 V, a rated discharge capacity of 3.4 Ah, a discharge energy of 52 Wh, and an energy density of 187 Wh / l. This battery pack is denoted as P1.

On the other hand, by combining the same type of electrode and electrolyte used in Comparative Example 1, eight prismatic lithium secondary batteries of the same type as in FIG. 2 were manufactured. Eight batteries of the same specifications
A battery pack similar to that of FIG. 3 was assembled by connecting four series and two parallel. The average discharge, rated discharge capacity, discharge energy, and energy density of this battery pack were 15.2, respectively.
V, 3.4 Ah, 52 Wh, 187 Wh / l, which were the same as the battery pack of P1. This battery pack is denoted as P2.

After charging the battery packs P1 and P2 to the rated discharge capacity, a fire test was carried out. As a result, the battery pack P1 did not ignite or explode, and the battery pack P2 ignited or exploded. By using the oxygen-absorbing substance of the present invention, safety could be improved without loss of energy density of the assembled battery.

FIG. 4 shows an example in which a battery pack 13 as an assembled battery obtained by combining the prismatic lithium secondary batteries of the present invention is mounted on a notebook personal computer. 19 is a keyboard part,
Reference numeral 20 denotes a liquid crystal display unit. By using the prismatic lithium secondary battery of the present invention, the safety of the battery can be improved without reducing the energy density of the battery pack 13 composed of the lithium secondary battery. As in the case of using a conventional battery, the usable time of the electronic device can be ensured.

Embodiment 10 Using the positive electrode powder A, the negative electrode, and the electrolytic solution used in Embodiment 1, a 250 Wh class lithium secondary battery was manufactured. The appearance of the battery is a square shape as in FIG. 2, and the height, width, and depth of the battery are each 116.
mm, 160 mm and 45 mm. The number of prismatic lithium secondary batteries manufactured in this example was eight, and they were manufactured by the method described below.

The same positive electrode active material, composite powder A, and polyvinylidene fluoride as in Embodiment 1 were mixed at a weight ratio of 90: 6: 4, and 1-methyl-2-pyrrolidone was added, followed by thorough kneading. Thus, a positive electrode slurry was prepared.

According to the doctor blade method, a thickness of 20 μm
The positive electrode slurry was applied to the surface of the positive electrode current collector made of aluminum foil. After drying this positive electrode at 180 ° C. for 2 hours, the positive electrode active material coated surface was cut into a height of 100 mm and a width of 150 mm to produce a positive electrode. The electrode thickness was 0.6 mm.

The negative electrode was manufactured according to the first embodiment. A natural graphite powder having an average particle size of 5 μm and a binder were mixed at a weight ratio of 95: 5, 1-methyl-2-pyrrolidone was added as an organic solvent, and the mixture was sufficiently kneaded to prepare a negative electrode slurry. A negative electrode slurry was applied to the surface of a negative electrode current collector made of a copper foil having a thickness of 20 μm by a doctor blade method. After drying the negative electrode at 180 ° C. for 2 hours, the negative electrode active material coated surface was
The negative electrode was produced by cutting into a height of 100 mm and a width of 150 mm. The electrode thickness was 0.5 mm.

The electrolytic solution used in the present embodiment was prepared by mixing a mixed solvent of ethylene carbonate and dimethyl carbonate with:
A non-aqueous electrolyte in which 1 mol / liter of LiBF4 was dissolved was prepared.

The above-prepared positive electrode, negative electrode and non-aqueous electrolyte were combined to obtain a height of 116 mm, a width of 160 mm and a depth of 45 m.
Eight m-type square lithium secondary batteries were produced. The configuration of the battery of the present embodiment is the same as that of FIG. Battery total capacity is 68
Ah, average operating voltage 3.8 V, discharge energy 260 Wh.

In order to avoid contact with the negative electrode at the time of laminating the electrodes, the positive electrode 1 was inserted into a polyethylene separator 3 processed into an envelope. An electrode group in which this and the negative electrode 2 were alternately laminated was inserted into the battery can 4. The positive electrode 1 was connected to the positive electrode lead 5, and was electrically connected to the positive electrode external terminal 11 from the bottom of the battery lid 6.

Further, the negative electrode 2 is connected to the negative electrode lead 7,
The negative electrode lead 7 was electrically connected to the negative electrode external terminal 12 from the bottom of the battery lid 6. After laser welding the battery lid 6 and the battery can 4, a non-aqueous electrolyte was vacuum-injected from the injection port 10 of the battery lid 6, and the injection port 10 was sealed. In order to release the internal pressure of the battery, a safety valve 8 having a burst valve made of Al foil was attached to the battery lid 6.

With such a configuration, electrochemical energy can be extracted from the positive electrode external terminal 11 and the negative electrode external terminal 12, and can be recharged. The battery manufactured in Embodiment 10 is denoted by symbol B14.

Eight batteries B manufactured in Embodiment 10
14 were connected in series to manufacture a 2 kWh battery pack, and a battery pack module 21 including 20 battery packs was mounted on an electric vehicle 22 as shown in FIG. A vent 23 is provided on the front of the electric vehicle so that outside air flows from the hood to the vehicle body during normal running. When the battery pack module 21 is installed inside the hood of the electric vehicle, and the driver operates the control device 24 with the steering wheel, the converter 25
Is operated to increase or decrease the output from the battery module 21.

The electric vehicle was driven by driving the motor 26 and the wheels 27 using the electric power supplied from the converter 25. By using the oxygen-absorbing substance of the present invention, it becomes possible to suppress ignition and explosion of a lithium secondary battery that occurs in an electric vehicle due to an accident such as a collision.

Further, the same effect can be obtained for a hybrid electric vehicle using a gasoline engine and a battery together by using the oxygen absorbing material of the present invention for the positive electrode.

[Embodiment 11] FIG. 6 shows a wheelchair for medical and nursing care 2 equipped with a power source 21 composed of a battery module or a module of 2 to 5 battery modules manufactured in Embodiment 10.
8 is an example. The angle can be adjusted by operating the controller 29 on the wheelchair 28 for medical care while the user is in the vehicle and operating the drive units provided on the backrest seat 30 and the footrest seat 31.

By utilizing this function, the footrest sheet 31 is lowered when the user gets on and off the vehicle, and the backrest seat 30 and the footrest seat 3 are used when the user rests.
Level 1 In addition, since the wheelchair 28 for medical care has the wheels 27 for movement, the user can operate the controller 29 to move to the target position. As shown in Tables 1 and 2, the medical care and wheelchair 28 of the present embodiment ignites and explodes even in a high-temperature environment as compared with the case where the lithium secondary battery of Comparative Example 1 is used. It is a very low risk product.

The lithium secondary battery and the assembled battery of the present invention
Notebook personal computers according to Embodiments 9, 10, and 11,
Not only electric vehicles and medical care wheelchairs, but also power-saving electronic devices such as personal computers, pen input computers, notebook computers, fax machines, mobile phones,
It can be applied to copiers, stationary TVs, head mounted TVs, LCD TVs, videos, video cameras, electronic notebooks, calculators, electronic notebooks with communication functions, toys, etc., and requires a large power and large capacity power supply. Equipment systems, such as large computers, electric tools, vacuum cleaners, air conditioners, game devices with virtual reality functions, electric bicycles, walking aids for medical care, mobile beds for medical care, escalators, elevators, It can be mounted on products such as forklifts, golf carts, emergency power supplies, road conditioners, and power storage systems, and the same effects as those of the above-described embodiment can be obtained.

[0124]

According to the present invention, the use of a positive electrode containing a composite material of an oxygen-absorbing material composed of a metal oxide and a conductive agent and a positive electrode active material as a positive electrode of a lithium secondary battery enables high temperature operation. Sometimes oxygen generated from the positive electrode can be captured,
The oxidation reaction of the electrolyte can be reduced. as a result,
The battery can be prevented from igniting or exploding during overcharging or when used in a high-temperature environment.

[Brief description of the drawings]

FIG. 1 is a structural diagram of a cylindrical lithium secondary battery using a positive electrode of the present invention.

FIG. 2 is a structural diagram of a prismatic lithium secondary battery using the positive electrode of the present invention.

FIG. 3 is a diagram showing a battery pack including the prismatic lithium secondary battery of FIG. 2;

FIG. 4 is a diagram showing a notebook computer equipped with the battery pack of FIG. 3;

FIG. 5 is a diagram showing an electric vehicle equipped with an assembled battery module including 20 2 kWh assembled batteries.

FIG. 6 is a diagram showing a wheelchair for medical care, on which the battery pack or battery module of the present invention is mounted.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Positive electrode, 2 ... Negative electrode, 3 ... Microporous film made of polyethylene, 4 ... Battery can, 5 ... Positive electrode lead, 6 ... Battery lid, 7 ... Negative electrode lead, 8 ... Safety valve, 9 ... Gasket, 10 ... Liquid inlet, 11 ... Positive electrode external terminal, 12 ... Negative electrode external terminal, 13 ...
Battery pack, 14 control panel, 15 rectangular lithium secondary battery, 16 positive external terminal, 17 negative external terminal, 1
8 ... Recommon terminal

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor, Hisashi Ando 7-1-1, Omika-cho, Hitachi City, Ibaraki Prefecture Within Hitachi Research Laboratory, Hitachi, Ltd. (72) Inventor Ren Muranaka 7, Omika-cho, Hitachi City, Ibaraki Prefecture No. 1 in the Hitachi Research Laboratory, Hitachi, Ltd.

Claims (4)

[Claims] 1. A lithium secondary battery comprising a positive electrode, a negative electrode, and an electrolyte, wherein the positive electrode contains a composite material of an oxygen absorbing material made of a metal oxide and a conductive agent, and a positive electrode active material. A rechargeable lithium battery. 2. A lithium secondary battery comprising a positive electrode, a negative electrode, and an electrolyte, wherein the positive electrode comprises a positive electrode current collector, and a positive electrode mixture adhered to the positive electrode current collector. The agent is a conductive agent having a fixed oxygen absorbing material made of a metal oxide, a positive electrode active material,
A lithium secondary battery comprising: a binder. 3. The oxygen absorbing material according to claim 1, wherein the oxygen absorbing substance has a chemical formula of CuO _1-α , Cu ₂ O _1-β , Fe ₂ O _3-γ , F
e ₃ O _4-δ , FeO _1-ε , SnO _2-ζ , ZnO _1-η , TiO _2-θ , Ti ₂ O
_3-κ , TiO _1-λ , V ₂ O _5-ν , VO _2-ξ , VO _1-σ , MoO _2-τ , M
oO _3-υ , MnO _1-φ , MnO _2-χ , Mn ₂ O _3-ψ , where α = 0
~ 0.8, β = 0 ~ 0.8, γ = 0 ~ 0.8, δ = 0 ~ 0.8, ε = 0 ~
0.8, ζ = 0-1.8, η = 0-0.8, θ = 0-0.8, κ = 0-0.
8, λ = 0 to 0.8, ν = 0 to 2.8, ξ = 0 to 0.8, σ = 0 to 0.
8, τ = 0 to 1.8, υ = 0 to 0.8, φ = 0 to 0.8, χ = 0 to 1.
8. A lithium secondary battery comprising at least one kind of metal oxides among metal oxides represented by ψ = 0 to 0.8. 4. A method for producing a lithium secondary battery comprising a positive electrode, a negative electrode, and an electrolyte, wherein the positive electrode comprises a conductive agent having an oxygen absorbing material made of a metal oxide fixed thereon, and a positive electrode active material and a binder. Mixed, the mixed positive electrode mixture is attached to a positive electrode current collector using an organic solvent, and the attached positive electrode current collector is dried to produce the negative electrode. The negative electrode is obtained by mixing a negative electrode active material and a binder. A method for producing a lithium secondary battery, comprising: attaching the mixed negative electrode mixture to a negative electrode current collector using an organic solvent; and drying the attached negative electrode current collector.