JPH1116571A - Battery, and electric apparatus using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery with high capacity of a secondary battery, long life, low overvoltage in charge and discharge, improved rate property, and high safety of no explosion and firing in overcharging. SOLUTION: At least one kind of a negative active material is a carbon material containing an element to form a compound with an alkali metal and an element not to form a compound with an alkali metal, and at least one kind of a positive active material is a compound oxide of formula Aw Nv Nix My O2 (A is at least one kind selected from alkali metals, N is at least one kind selected from Mg, P, M is at least one kind selected from Mn, Co, Al, and w, v, x, y are 0.05<=w<=1.2, 0.0001<=v<=0.02, 0.6<=x<=0.95, 0.005<=y<=0.4, respectively).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery that can be reversibly charged and discharged a plurality of times, and more particularly to a secondary battery using a non-aqueous electrolyte.

[0002]

2. Description of the Related Art In recent years, secondary batteries have become one of the essential components that are indispensable as power sources for personal computers and mobile phones, or as power sources for electric vehicles and power storage.

A portable computer (including a pen computer) and a personal digital assistant (Personal Digita)
l Assistant or Personal Intelligent Communic
Requirements for mobile communication (mobile computing) such as an ator or a handheld communicator include miniaturization and weight reduction.

However, since the power consumed by the backlight of the liquid crystal display panel and the drawing control is high, and the capacity of the secondary battery is still insufficient at present, the system is made compact and lightweight. Is in a difficult situation.

[0005] Further, with the increase in global environmental problems, electric vehicles that do not emit exhaust gas or noise are attracting attention.
However, current batteries have problems such as short running distance, poor acceleration, small space inside the vehicle, and poor stability of the vehicle body due to low energy density and low output density.

[0006] Among secondary batteries, lithium secondary batteries using a non-aqueous electrolyte are attracting attention because they are expected to have high voltage, light weight, and high energy density. As the positive electrode material of this secondary battery, conductive polymers such as polyaniline, polyacene, polyparaphenylene and Li _x
CoO ₂ , Li _x NiO ₂ , Li _x Mn ₂ O ₄ , Li _x Fe
Representative examples are oxides of transition metals such as O ₂ , V ₂ O ₅ , Cr ₂ O ₅ , and MnO _2, and chalcogenite compounds such as TiS ₂ and MoS ₂ .

In particular, the positive electrode of a secondary battery such as Li _x CoO ₂ or Li _x NiO ₂ disclosed in JP-A-55-136131 is L
When i-metal is used as the negative electrode, a high energy density can be expected since it has an electromotive force of 4 V or more. However, these cannot be said to have sufficient performance in terms of overvoltage at charge / discharge, self-discharge characteristics, high temperature characteristics, and the like, in addition to the fact that actually usable capacity is still low or the life is short.

[0008] In addition, there has been a problem in terms of safety such that the positive electrode active material is decomposed by heat during overcharging, causing thermal runaway, and the battery is ignited or exploded.

Conventionally, various active material compositions have been proposed in order to achieve a higher capacity and longer life of the positive electrode. For example, as a material for improving the cycle characteristics, lithium represented by the chemical formula Li _x MO ₂ (M represents one or more elements selected from Co, Ni, Fe, and Mn) is used as the positive electrode active material. Using composite oxides containing
2-306022 JP), or the formula Li _x M _y Ge _z O _p
(M is one or more transition metal elements selected from Co, Ni and Mn, 0.9 ≦ x ≦ 1.3, 0.8 ≦ y ≦ 2.0, 0.01
The use of a composite oxide represented by ≦ z ≦ 0.2, 2.0 ≦ p ≦ 4.5) is disclosed (JP-A-7-29603).

Further, the cycle characteristics, those for improving the self-discharge _{characteristics, AxM y N z O 2 (} A is at least one selected from an alkali metal, M is a transition metal, N represents Al, In , Sn, at least one selected from the group consisting of 0.05 ≦ x ≦ 1.10, 0.85 ≦ y ≦
1.00, 0.001 ≦ z ≦ 0.10) (JP-A-7-176302). Lithium is used to improve capacity and cycle characteristics.
_y Ni _(1-x) M _x O ₂ (M is at least one element selected from the group consisting of Cu, Zn, Nb, Mo, and W; 0 <x <1,
It is disclosed that a composite oxide represented by 0.9 ≦ y ≦ 1.3) is used (JP-A-6-283174).

In order to improve the cycle characteristics and enhance the load characteristics, the chemical formula Li _x Mg _y Co _z Ni
_1-yz O _a (0.95 ≦ x ≦ 1.05, 0.02 ≦ z ≦ 0.1
5, a composite oxide represented by 0.003 <y <0.02, and if z <0.02, 0.003 <y <0.05, a = 2) is used. No. 185863).

Regarding the negative electrode material, Li ions are doped,
Highly crystalline graphite and amorphous carbon that can be undoped are mainly used. However, in reality, in addition to the fact that the capacity actually available is still low, or the life is short, the load characteristics are low, and the like, Li is deposited in the form of resin on the negative electrode surface during rapid charging or overcharging, causing a short circuit. And the irreversible capacity increases, and the battery ignites and explodes.

[0013] Conventionally, in order to increase the capacity of the negative electrode and improve the characteristics of the negative electrode, for example, the surface of highly crystalline carbon particles forming the core is coated with a film containing a Group VIII metal element, and the surface is further coated thereon. Using a composite coated with carbon (Japanese Unexamined Patent Publication No. 5-299)
No. 073). In order to improve the cycle characteristics, H / C <0.15, face spacing> 3.
It has been proposed to use a mixture of a carbon material having a temperature of 37 ° and Lc <150 ° and a metal capable of being alloyed with Li (JP-A-2-121258). Further, as a material capable of increasing the capacity, it has been proposed to use a material obtained by adhering graphite to copper oxide (Japanese Patent Laid-Open No. 5-136099).

[0014]

The positive electrode active material has the formula L
i _x MO ₂ (M is Co, Ni, Fe, represent one or more elements selected from among Mn) when using a lithium-containing composite oxide represented by the cycle life is improved. However, it is hard to say that the characteristics are sufficient in terms of capacity. In addition, it has disadvantages such as a decrease in voltage. A _x M _y
N _z O ₂ (A is at least one selected from alkali metals, M is a transition metal, N is at least one selected from the group consisting of Al, In and Sn, and 0.05 ≦ x
≤ 1.10, 0.85 ≤ y ≤ 1.00, 0.001 ≤ z ≤
When the composite oxide represented by 0.10) is used, the cycle life is similarly improved, but the capacity that can be actually used for charging and discharging is reduced, so that the capacity cannot be increased.

[0015] The chemical in the positive electrode active material formula _{Li x M y Ge z O p} (M
Is one or more transition metal elements selected from Co, Ni and Mn, 0.9 ≦ x ≦ 1.3, 0.8 ≦ y ≦ 2.0, 0.01 ≦
When a composite oxide represented by z ≦ 0.2, 2.0 ≦ p ≦ 4.5) is used, the capacity and cycle life are improved.
However, the thermal runaway reaction during overcharge cannot be suppressed.

Li _y Ni _(1-x) M _x O ₂ (M is Cu, Zn,
At least one element selected from the group consisting of Nb, Mo and W, when using a composite oxide represented by 0 <x <1, 0.9 ≦ y ≦ 1.3), or using a chemical formula of Li _x Mg _y Co _z Ni
_1-yz O _a (0.95 ≦ x ≦ 1.05, 0.02 ≦ z ≦ 0.1
5, if 0.003 <y <0.02, z <0.02, then 0.003 <y <0.05, a = 2). .

As described above, in addition to increasing the capacity and prolonging the life of the positive electrode material for a secondary battery, reducing the overvoltage during charging and discharging, and improving the rate characteristics, it is hard to see a sufficient improvement method in terms of safety. Not issued.

In the case where a complex in which the surface of highly crystalline carbon particles forming the core of the negative electrode active material is coated with a film containing a Group VIII metal element and carbon is further coated thereon is used, The carbon aids in the intercalation of lithium, which increases the capacity and improves load characteristics.

However, since the formation of resinous precipitates of Li during overcharge cannot be suppressed, it reacts with the electrolyte or the positive electrode in the battery to cause an explosion, leaving a problem in terms of safety.

H / C <0.15, face spacing> 3.37 °, L
When a mixture of a carbon material having c <150 ° and a metal which can be alloyed with Li is used, the cycle life is apparently improved. However, when the cycle is prolonged, the expansion and contraction of the metal alloyed with Li is large. Collapse and falling off occur, and a sufficient cycle life cannot be obtained.

In the case of using graphite with copper oxide adhered thereto, a high capacity can be obtained, but the formation of a resinous precipitate of Li during overcharge cannot be suppressed.

As described above, in the conventional combination of the positive electrode and the negative electrode, it is possible to achieve a high capacity, a long life, a low overvoltage during charge and discharge, and an improvement in the rate characteristics, and an explosion and ignition during overcharge. No safe batteries have been obtained.

An object of the present invention is to improve these battery characteristics of a positive electrode material for a secondary battery.

[0024]

According to the battery of the present invention, at least one of the negative electrode active materials is a carbon material containing an element forming a compound with an alkali metal and an element not forming a compound with an alkali metal. at least one of the active material has the general formula _{a w N v Ni x M y} O 2 ( where a is at least one selected from an alkali metal, N is at least one selected Mg, from P, M is At least one selected from Mn, Co, and Al, and w, v, x, and y are respectively 0.05 ≦ w ≦ 1.2, 0.0001 ≦ v ≦ 0.0.
2,0.6 ≦ x ≦ 0.95, 0.005 ≦ y ≦ 0.4).

The positive electrode active material in the novel battery of the present invention has been made of the general formula _{A w N v Ni x M y} O 2, A
Is at least one selected from alkali metals, for example, L
i, Na and K, of which Li is preferable. The value of w varies depending on the state of charge and the state of discharge, and its range is 0.05.
≦ w ≦ 1.2. In other words, deintercalation of A ions occurs due to charging and the value of w decreases, and intercalation of A ions occurs and discharging increases the value of w.

N is at least one selected from Mg and P, preferably Mg, and more preferably a combination of Mg and P. The value of v representing the amount of N does not fluctuate due to charging and discharging, but 0.0001 ≦ v ≦
0.02. When the value of v is less than 0.0001, the effect of N is not sufficiently exerted, the cycleability in deep charge and deep discharge for obtaining a high capacity is poor, and the capacity is undesirably reduced. On the other hand, when the value of v exceeds 0.02, the capacity is undesirably reduced. The atomic ratio of Mg / P in the combination of Mg and P is desirably 0.1 or more and 12 or less.

The value of x representing the amount of Ni is 0.6 ≦ x
≦ 0.95. When the value of x is less than 0.6, the capacity is significantly reduced, which is not preferable. Also, if the value of x is 0.
If it exceeds 95, the cyclability in deep charge and deep discharge is poor, which is not preferable.

M is at least one selected from Mn, Co, and Al. The value of y does not vary depending on the state of charge and the state of discharge, and its range is 0.005 ≦ y ≦ 0.4. When the value of y is less than 0.005, the effect of M is not sufficiently exhibited, and the cycleability in deep charging and deep discharging is poor, which is not preferable. On the other hand, when the value of y exceeds 0.4, the capacity is decreased and the voltage is further decreased, which is not preferable.

[0029]

DETAILED DESCRIPTION OF THE INVENTION At least one kind of the negative electrode active material in the novel battery of the present invention is a carbon material containing an element forming a compound with an alkali metal and an element not forming a compound with an alkali metal. Contains at least one element selected from the group consisting of lead, tin, aluminum, silicon, indium, gallium, silver, boron, and magnesium,
Tin, aluminum, silicon, silver, and boron; more preferably, tin, aluminum, silicon, and silver; and most preferably, tin and silver.

The element which does not form a compound with an alkali metal includes at least one element selected from the group consisting of iron, copper, cobalt, nickel, phosphorus, sulfur, and selenium. , Phosphorus and sulfur, more preferably iron, copper, phosphorus and sulfur, and most preferably iron and copper.

An element forming a compound with an alkali metal,
The element that does not form a compound with the alkali metal is present on the carbon material in the form of at least one of a simple substance, an intermetallic compound, and an oxide, or a combination of two or more thereof.

For example, when tin is contained as an element forming a compound with an alkali metal, tin alone, an oxide containing tin, or an intermetallic compound containing tin may be used. In the case of tin, it is preferably an oxide containing tin, and particularly preferably amorphous. In the case of silver, silver alone or an intermetallic compound containing silver is preferred.

When copper is contained as an element which does not form a compound with an alkali metal, copper alone, an oxide containing copper, or an intermetallic compound containing copper may be used. For copper,
Preferably, copper alone or an intermetallic compound containing copper is preferable, and an intermetallic compound of silver and copper is particularly desirable. In the case of phosphorus or sulfur, phosphorus or sulfur alone, an oxide containing phosphorus or sulfur, a phosphate or a sulfate, or an intermetallic compound containing phosphorus or sulfur may be used. The element that forms a compound with an alkali metal and the element that does not form a compound with an alkali metal have a particle size of 1000 μm by an electroless plating process, an electrolytic plating process, or a dry process.
By carrying the following particles in the carbon material,
The effects of the above elements are sufficiently exhibited. Particle size 1000Å
If it is larger than this, the element that forms a compound with the alkali metal undergoes a large volume change when inserting and releasing the alkali metal, so that it collapses and falls off, resulting in a short cycle life.

As the negative electrode active material, graphite, pyrolytic graphite, carbon fiber, vapor-grown carbonaceous material, pitch-based carbonaceous material, coke-based carbonaceous material, phenol-based carbonaceous material, rayon-based carbonaceous material, poly One or more of low-crystalline carbon and high-crystalline carbon selected from the group consisting of acrylonitrile-based carbonaceous materials, glassy carbon, carbon black, furfuryl alcohol-based carbonaceous materials, and conductive materials such as polyparaphenylene. By including a carbon material obtained by combining two or more of the above, the battery of the present invention exhibits excellent characteristics.

Examples of the electrolyte include propylene carbonate, propylene carbonate derivatives, ethylene carbonate, butylene carbonate, vinylene carbonate, gamma-butyl lactone, dimethyl carbonate, and the like.
Diethyl carbonate, methyl ethyl carbonate,
1,2-dimethoxyethane, 2-methyltetrahydrofuran, dimethylsulfoxide, 1,3-dioxolane, formamide, dimethylformamide, dioxolane, acetonitrile, nitromethane, gisanmethyl, methyl acetate, methyl propionate, ethyl propionate,
Phosphate triester, trimethoxymethane, dioxolane derivative, diethyl ether, 1,3-propanesultone, sulfolane, 3-methyl-2-oxazolidinone,
At least one non-aqueous solvent selected from the group consisting of tetrahydrofuran, tetrahydrofuran derivative, dioxolan, 1,2-diethoxyethane, and halides thereof, and a lithium salt such as LiClO ₄ ,
LiBF ₄ , LiPF ₆ , LiCF ₃ SO ₃ , LiCF ₃ C
O ₂ , LiAsF ₆ , LiSbF ₆ , LiB ₁₀ Cl ₁₀ , L
a mixed solution of at least one salt selected from the group consisting of iAlCl ₄ , LiCl, LiBr, Lil, lithium lower aliphatic carboxylate, lithium chloroborane, lithium tetraphenylborate, etc. For example, by using a gel electrolyte mixed with one or more selected from the group consisting of polyacrylonitrile, polyethylene oxide, polyvinylidene fluoride, polymethyl methacrylate, hexafluoropropylene,
The battery of the present invention shows good characteristics. The use of the reversibly chargeable / dischargeable battery of the present invention is not particularly limited. For example, a notebook personal computer, a pen input personal computer, a pocket personal computer, a notebook word processor, a pocket word processor, an electronic book player, a mobile phone, and a cordless phone handset , Pager, handy terminal, portable copy, electronic organizer,
Calculator, LCD TV, electric shaver, electric tool, electronic translator, car phone, transceiver, voice input device, memory card, backup power supply, tape recorder, radio, headphone stereo, portable printer, handy cleaner, portable CD, video movie, Power supplies for equipment such as navigation systems, refrigerators, air conditioners, televisions, stereos, water heaters, microwave ovens, dishwashers, washing machines, dryers, game equipment, lighting equipment, toys, road conditioners, medical equipment, automobiles, It can be used as a power source for electric vehicles, golf carts, electric carts, power storage systems, and the like. It can be used not only for civilian purposes but also for military use and space.

A carbon material containing an element forming a compound with an alkali metal and an element not forming a compound with an alkali metal is used as at least one kind of the negative electrode active material, and at least one kind of the general formula A _{w N v Ni x M y O 2} ( where a is at least one selected from an alkali metal, N is at least one selected Mg, from P,
M is at least one selected from Mn, Co, and Al, and w, v, x, and y are respectively 0.05 ≦ w ≦ 1.2,
0.0001 ≦ v ≦ 0.02, 0.6 ≦ x ≦ 0.95, 0.9.
005 ≦ y ≦ 0.4), it is possible to achieve high capacity, long life, low overvoltage during charge and discharge, and improvement in rate characteristics, and A highly safe battery that does not explode or ignite during overcharge can be obtained. Further, by using the electrode of the present invention and a battery using the same in various systems, the size and weight of the system can be reduced. In addition, it can be applied to a system that requires charging and discharging at a high rate.

The operation of the positive electrode active material of the present invention will be specifically described. Since Mn, Co, and Al are harder to oxidize than Ni,
The service life can be extended by these pillar effects. The pillar effect refers to the effect of suppressing the stress of the crystal structure by pinning in the crystal because the specific element itself does not participate in the oxidation-reduction reaction in charge and discharge, that is, does not involve a change. Say Furthermore, since P and Mg are typical elements, they do not cause an oxidation-reduction reaction in charge and discharge unlike Ni, so that a longer life can be achieved by the pillar effect. Since P has a small ionic radius, it can shrink the lattice volume of the positive electrode active material, suppress collapse due to expansion of the lattice volume during charging, and extend the life. Further, since P exists at the interstitial position, the capacity does not decrease due to the substitution of P, and a high capacity can be maintained. Since Mg, P, and Al have low oxygen releasing ability and are stably present as oxides, safety at high temperatures can be improved.

Mg is the main structural ion N
Since it has a valence different from i or Li, and P is inserted at an interstitial position, the electronic structure in the crystal changes, and an improvement in electrical conductivity is expected. The overvoltage can be reduced, the rate characteristics and the temperature characteristics can be improved, and the capacity can be increased. In addition, since Mg has a smaller ionic radius than Li ions, substitution of the Li site with the Li ions causes the lattice volume of the positive electrode active material to shrink, thereby suppressing collapse due to expansion of the lattice volume during charging and extending the life. Can be. Further, since Mg has a pillar effect after Li is released by substitution with Li sites, the contraction of the lattice that occurs at the end of charging is suppressed, there is almost no lattice stress, and the life is prolonged even when overcharging is performed. I can do it.

Next, the operation of the negative electrode active material of the present invention will be described.
At the time of overcharging, the reaction of Li and an element forming a compound with an alkali metal can suppress the generation of Li resinous precipitation on the carbon material, and a highly safe battery with less explosion or ignition can be obtained. Further, at the time of overdischarge, the release reaction of Li from the above compound obtained by the reaction with Li,
The reduction reaction of the electrolytic solution on the carbon material can be prevented, the deterioration of the positive electrode active material can be suppressed, and the life can be extended.

Further, by including an element that does not form a compound with an alkali metal, it is possible to relatively easily and highly disperse the element that forms a compound with an alkali metal into particles of 1000 ° or less on a carbon material. Has been confirmed.

The effect of highly dispersing into particles of 1000 ° or less is that the stress of expansion and contraction during insertion and release of Li in the element forming the compound with the alkali metal can be relaxed, and the life can be greatly extended. .

Further, by supporting the element shown in the present invention on a carbon material, the magnetic properties of the carbon material can be changed. Thereby, the magnetic trap of Li remaining in the layer can be released, and the release of Li becomes easy. Thereby, a capacity substantially corresponding to the theoretical capacity can be obtained, and irreversible capacity loss can be reduced.

As elements forming a compound with an alkali metal, lead, tin, aluminum, silicon, indium, gallium, silver, boron, and magnesium are preferable because of excellent cycle reversibility.

As an element which does not form a compound with an alkali metal, iron, copper, cobalt, nickel, phosphorus, sulfur and selenium can easily and highly disperse an element which forms a compound with an alkali metal. Above all, simple substances or intermetallic compounds of silver, tin, copper and aluminum also have the effect of improving the electrical conductivity, and are therefore effective in improving the rate characteristics and temperature characteristics.
When phosphates, sulfates, and oxides are contained, the presence of these matrices can alleviate the stress of expansion and contraction during insertion and release of Li, and extend the life.

The operation of the combination of the negative electrode active material and the positive electrode active material of the present invention will be described. The safety at the time of overcharging at a low temperature, which is a problem when the positive electrode active material of the present invention is used, can be improved by combining the negative electrode active material of the present invention.

In the overcharged state, if the amount of metallic Li deposited on the negative electrode is large, the deposited Li and the positive electrode active material of the present invention react rapidly, generating enormous heat at a low temperature and causing ignition and explosion. Reach. When a conventional carbon material such as natural graphite or mesophase pitch graphite is used for the negative electrode, overcharging at room temperature does not result in ignition or explosion even when combined with the positive electrode active material of the present invention. When the temperature is lower than ℃, metallic Li tends to precipitate on the carbon surface, and reacts with the deposited Li to ignite or explode.

The negative electrode active material of the present invention does not precipitate metallic Li even at 10 ° C. or lower, so that ignition and explosion can be suppressed even at low temperature overcharge.

Further, by the combination of the negative electrode active material and the positive electrode active material of the present invention, there is no capacity reduction at the time of overdischarge, and the overdischarge characteristics are greatly improved.

When a conventional carbon material, for example, natural graphite or mesophase pitch-based graphite is used for the negative electrode and the positive electrode active material of the present invention is used for the positive electrode, in the case of overdischarge, the electrolytic solution is decomposed on the carbon material, and The substance reacts on the positive electrode active material of the present invention to deteriorate the positive electrode active material.

In the negative electrode active material of the present invention, the reduction reaction of the electrolytic solution on the carbon material at the time of overdischarge can be suppressed, so that the positive electrode active material can be extended without any deterioration. Further, low-temperature characteristics and low-temperature rate characteristics, which are problems when the negative electrode active material of the present invention is used, can be improved by combining the positive electrode active material of the present invention.

[0051] Conventional cathode materials, for example, A _x M _y N _z O
₂ (A is at least one selected from alkali metals, M is a transition metal, N is at least one selected from the group consisting of Al, In, Sn, and 0.05 ≦ x ≦ 1.0.
10, 0.85 ≦ y ≦ 1.00, 0.001 ≦ z ≦ 0.1
When 0) is used, the electric conductivity of the positive electrode active material is significantly reduced at a low temperature, particularly at −20 ° C. or lower, so that the capacity of the positive electrode is significantly reduced. As a result, the operating potential of the negative electrode greatly deviates from the design value, and reaches the Li deposition region or the electrolytic solution decomposition region, and the battery cannot be charged or discharged.

The positive electrode active material of the present invention has a high electrical conductivity, and exhibits a metallic behavior in which the electrical conductivity increases particularly at low temperatures. By combining with the positive electrode active material of the present invention, -2
Even at 0 ° C. or lower, the same capacity as at room temperature is obtained, and the operating potential of the negative electrode greatly deviates from the design value,
There is no problem such as reaching the decomposition area of the electrolyte,
The low temperature characteristics are greatly improved.

As the combination of the positive electrode and the negative electrode of the present invention with the electrolyte, LiClO ₄ , LiBF ₄ , LiP
F ₆ , LiCF ₃ SO ₃ , LiCF ₃ CO ₂ , LiAsF ₆ ,
LiSbF ₆ , LiB ₁₀ Cl ₁₀ , LiAlCl ₄ , Li
When Cl, LiBr, LiI, lithium lower aliphatic carboxylate, lithium chloroborane, and lithium tetraphenylborate are used, they show excellent temperature characteristics. Especially Li
When at least one of BF ₄ , LiPF ₆ , LiCF ₃ SO ₃ , and LiCF ₃ CO ₂ is used, the elution of the M element in the positive electrode active material of the present invention is suppressed even at 60 ° C. Demonstrates excellent effect on high temperature characteristics.

Further, as a combination of the positive electrode and the negative electrode of the present invention with an electrolytic solution, propylene carbonate, a propylene carbonate derivative, ethylene carbonate, butylene carbonate, vinylene carbonate, gamma-butyl lactone, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate are used as solvents. 1,2-dimethoxyethane, 2-methyltetrahydrofuran, dimethylsulfoxide, 1,3-dioxolane, formamide, dimethylformamide, dioxolane, acetonitrile,
Nitromethane, gisan methyl, methyl acetate, methyl propionate, ethyl propionate, phosphoric acid triester,
Trimethoxymethane, dioxolane derivative, diethyl ether, 1,3-propanesultone, sulfolane, 3-
Methyl-2-oxazolidinone, tetrahydrofuran,
When a tetrahydrofuran derivative, dioxolan, or 1,2-diethoxyethane is used, it shows excellent life characteristics.

In particular, propylene carbonate, propylene carbonate derivatives, ethylene carbonate, butylene carbonate, vinylene carbonate, gamma-butyl lactone, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, 1,2-dimethoxyethane, 2-methyltetrahydrofuran, dimethyl sulfoxide When at least one is used, since the irreversible reaction between the negative electrode active material of the present invention and a solvent is suppressed,
Exhibits excellent effects on life characteristics.

Further, when the solvent contains a halide of the above-mentioned solvent as a combination of the positive electrode and the negative electrode of the present invention and the electrolytic solution, the safety is remarkably improved. In particular, propylene carbonate, propylene carbonate derivatives, ethylene carbonate, butylene carbonate, vinylene carbonate, gamma-butyl lactone, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, 1,2-dimethoxyethane, 2-methyltetrahydrofuran, dimethyl sulfoxide Part of the element
_{F, -CF, -CF 2, -CF} 3, -Cl, -CCl, -
When at least one of CCl ₂ and —CCl ₃ is used, the exothermic reaction between the cathode active material of the present invention and the solvent under the overcharge condition is suppressed, the establishment of ignition is remarkably reduced, and Show safety.

As the combination of the positive electrode and the negative electrode of the present invention with the electrolytic solution, the mixture of the above-mentioned lithium salt and the solvent may be prepared from the group consisting of polyacrylonitrile, polyethylene oxide, polyvinylidene fluoride, polymethyl methacrylate, and hexafluoropropylene. When a gel electrolyte mixed with at least one selected is used, an exothermic reaction of the cathode active material of the present invention and the gel electrolyte under an overcharge condition is suppressed, and the establishment of ignition is significantly reduced. And show high security. In addition, in the combination of the positive electrode active material of the present invention and the gel electrolyte, even at a high potential of 4.5 V, the positive electrode active material of the present invention can be charged, so that high capacity can be achieved.

Hereinafter, the present invention will be described in more detail with reference to specific examples.

(Example 1) Materials having compositions shown in Tables 1 and 2 were used as positive electrode materials, graphite was used as a conductive agent, and polyvinylidene fluoride was used as a binder at a weight ratio of 88: 7: 5.
After weighing and kneading for 30 minutes with a rake machine, thickness 2
It was applied to both sides of a 0 micron aluminum foil. A material having the composition shown in Tables 1 and 2 was used as the negative electrode material.
7% by weight of polyvinylidene fluoride as binder
The prepared mixture was applied to both surfaces of a copper foil having a thickness of 20 microns.

The positive and negative electrodes were roll-formed by a press machine, and the terminals were spot-welded and then vacuum-dried at 150 ° C. for 5 hours. A positive electrode and a negative electrode were laminated with a microporous polypropylene separator interposed therebetween, spirally wound, and inserted into an aluminum battery can. The negative electrode terminal was welded to the battery can, and the positive electrode terminal was welded to the battery lid.

As the electrolytic solution, a solution prepared by dissolving 1 mol of LiPF ₆ in 1 liter of a mixed solution of ethylene carbonate and diethyl carbonate was used, and the solution was injected into the battery can.
The battery lid was swaged to produce a cylindrical battery having a capacity of 1800 mAh. After charging the battery to 4.2V at 360mA, 36
Constant current charging / discharging at 0 mA to 2.7 V was performed, and the capacity, life, 1 C rate characteristics at -20 ° C, and 2C overcharge test at -20 ° C were evaluated. The results are shown in Tables 1 and 2.

Comparative Example 1 A battery was fabricated in the same manner as in Example 1 except that the materials shown in Tables 1 and 2 were used as the positive electrode material and the negative electrode material. The capacity, life, 1C rate characteristics at -20 ° C, and 2C overcharge test at -20 ° C were evaluated. The results are shown in Tables 1 and 2. There is an extremely low characteristic as compared with the first embodiment.

[0063]

[Table 1]

[0064]

[Table 2]

[0065]

According to the present invention, it is possible to realize high safety, compactness and light weight, good high-rate characteristics and long life of batteries and systems.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masanori Yoshikawa 7-1-1, Omikacho, Hitachi City, Ibaraki Prefecture Within Hitachi Research Laboratory, Hitachi, Ltd. (72) Inventor Ren Muranaka 7, Omikamachi, Hitachi City, Ibaraki No. 1 in the Hitachi Research Laboratory, Hitachi, Ltd.

Claims (6)

[Claims] At least one negative electrode active material of a battery comprising a negative electrode, a positive electrode, and a non-aqueous electrolyte containing a lithium salt and capable of being charged and discharged a plurality of times reversibly comprises an element forming a compound with an alkali metal, a carbon material containing an element which does not form a metal with a compound, and at least one said at least one of the positive electrode active material has the general formula _{a w N v Ni x M y} O 2 ( where a is selected from alkali metal And N is Mg,
P is at least one selected from P, and M is Mn, C
at least one member selected from the group consisting of w, v,
x and y are 0.05 ≦ w ≦ 1.2 and 0.0001 ≦
v ≦ 0.02, 0.6 ≦ x ≦ 0.95, 0.005 ≦ y ≦ 0.
(Representing the number 4). 2. One or more elements selected from the group consisting of lead, tin, aluminum, silicon, indium, gallium, silver, boron and magnesium as an element forming a compound with an alkali metal of the negative electrode active material. 2. The battery according to claim 1, further comprising at least one element selected from the group consisting of iron, copper, cobalt, nickel, phosphorus, sulfur, and selenium as an element that does not form a compound with an alkali metal. 3. The element that forms a compound with an alkali metal and the element that does not form a compound with an alkali metal are at least one of a simple substance, an intermetallic compound, and an oxide, or a combination of two or more thereof. The battery according to claim 1, which is present on the carbon material. 4. An element which forms a compound with an alkali metal and an element which does not form a compound with an alkali metal are formed into a particle having a particle size of 1000 ° or less by an electroless plating process, an electrolytic plating process, or a dry process. The battery according to claim 1, wherein the battery is supported on a carbon material. 5. The negative electrode active material includes graphite, pyrolytic graphite, carbon fiber, vapor-grown carbonaceous material, pitch-based carbonaceous material, coke-based carbonaceous material, phenol-based carbonaceous material, rayon-based carbonaceous material. One or a combination of low-crystalline carbon and high-crystalline carbon selected from the group consisting of conductive materials such as polyacrylonitrile-based carbon materials, glassy carbon, carbon black, furfuryl alcohol-based carbonaceous materials, and polyparaphenylene. 2. A carbon material comprising a combination of two or more of the following.
The battery according to 1. 6. A notebook personal computer, a pen input personal computer, a pocket personal computer, a notebook type word processor, a pocket word processor,
E-book player, mobile phone, cordless phone handset, pager, handy terminal, mobile copy,
Electronic organizer, calculator, liquid crystal television, electric shaver, electric tool, electronic translator, car phone, transceiver, voice input device, memory card, backup power supply, tape recorder, radio, headphone stereo, portable printer, handy cleaner, portable CD, Video movie, navigation system, refrigerator, air conditioner,
TV, stereo, water heater, microwave oven, dishwasher, washing machine, dryer, game equipment, lighting equipment, toy, road conditioner, medical equipment, automobile, electric car, golf cart, electric cart, power storage system An electric device, wherein the battery is the battery according to claim 1.