JP2000243445A - Nonaqueous electrolyte secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coin-shaped (button-shaped) nonaqueous electrolyte secondary battery capable of resisting a reflow temperature. SOLUTION: A lithium-containing manganese oxide expressed by LiMn2O4 is used as a positive-electrode active material, a molybdenum oxide expressed by a general expression of MoOx (2<=x<=3), a lithium titanate expressed by a general expression of LixTiyO4 (0.8<=x<=1.4, 1.6<=y<=2.2), iron sulfide, or niobium pentoxide is used for a negative electrode, a nonaqueous solvent is used having a boiling point of 200 deg.C or higher at ordinary temperatures, a fluorine- containing substance is used as a supporting salt. Glass fiber or a resin having a thermal deformation temperature of 230 deg.C or higher is used for a separator 109, and for a gasket 108, a resin having a thermal deformation temperature of 230 deg.C of higher is used to resist a reflow temperature and not to deteriorate battery performance in combination with electrodes in this nonaqueous electrolyte secondary battery.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coin-type (button-type) non-aqueous electrolyte secondary battery using a material capable of inserting and extracting lithium as an active material for a negative electrode and a positive electrode, and using a non-aqueous electrolyte having lithium ion conductivity. Things.

[0002]

2. Description of the Related Art Conventionally, coin-type (button-type) non-aqueous electrolyte secondary batteries have been increasingly used as backup power supplies for equipment because of their features such as high energy density and light weight. Most conventional coin-type (button-type) nonaqueous electrolyte secondary batteries require some form of addition of lithium to the active material of the negative electrode and the positive electrode. For example, in the case of a battery using a lithium-aluminum alloy for the negative electrode and a 3V-class lithium-containing manganese oxide for the positive electrode, it was necessary to press-bond lithium to aluminum of the negative electrode. In the case of a battery using carbon as the negative electrode and a lithium-containing manganese oxide of 3V class as the positive electrode, it was necessary to electrochemically insert lithium into the positive electrode.

[0003] In the battery, the material of the gasket for keeping the battery airtight and liquid-tight and insulating the positive and negative electrode cans is extremely important. Conventional gasket materials include chemical resistance,
Inexpensive polypropylene, which is excellent in elasticity and creep resistance, has good moldability, and can be injection molded, has been used. When the battery is mainly used as a memory backup power supply, a soldering terminal is welded to the battery, and then the battery is often soldered together with the memory element onto a printed circuit board. Conventionally, soldering on a printed circuit board has been performed using a soldering iron, but with the miniaturization and higher functionality of equipment, it is necessary to increase the number of electronic components mounted on the same area of the printed circuit board. Therefore, it has become difficult to secure a gap for inserting a soldering iron for soldering. Also, the soldering work has been required to be automated for cost reduction.

[0004] Therefore, a solder cream or the like is applied in advance to a portion on the printed circuit board where soldering is to be performed, and components are mounted on the portion, or after the components are mounted, small solder balls are supplied to the soldered portion. The soldering is performed by melting the solder by passing the printed circuit board on which the components are mounted in a furnace in a high-temperature atmosphere set so that the soldered portion has a temperature equal to or higher than the melting point of the solder, for example, 200 to 230 ° C. The method is used (hereinafter referred to as reflow soldering). The coin-type (button-type) non-aqueous electrolyte secondary battery of the conventional configuration has a drawback that the function as a battery is impaired at the time of reflow soldering because a material in consideration of heat resistance is not used.

[0005]

As described above, most of the conventional coin-type (button-type) non-aqueous electrolyte secondary batteries are
In the manufacturing process, it was necessary to add lithium to the active material of the negative electrode and the positive electrode in some form, so that it was necessary to use a lithium metal which was difficult to handle in manufacturing. Various processes and equipment were required to add lithium in a metallic state. For example, when lithium is added by punching, it is necessary to frequently perform maintenance such as wiping because lithium easily adheres to a punching die or the like.
In addition, facilities for storing lithium, which is a dangerous substance, were required.

[0006] In addition, in the production process, the addition of lithium to the active material of the negative electrode in any form lacks stability in reflow soldering. For example, in a coin-type (button-type) nonaqueous electrolyte secondary battery in which a lithium-manganese oxide Li4Mn5O12 of 3V class is used as a positive electrode and a lithium-aluminum alloy is used as a negative electrode, when a reflow solder is attached, most combinations of electrolyte and heat-resistant are used. The electrolytic solution reacts with the lithium alloy in the non-volatile battery member, causing rapid swelling and bursting.

[0007] Also, in a coin-type (button-type) nonaqueous electrolyte secondary battery using a 3V-class lithium-containing manganese oxide Li4Mn5O12 as a positive electrode and a negative electrode made of carbon contacted or electrochemically doped with lithium, the electrolyte is also used. Reacts with the lithium-doped negative electrode, causing rapid swelling and bursting. Further, in the conventional coin-type (button-type) nonaqueous electrolyte secondary battery, since the electrolyte, the separator, and the gasket cannot be kept at the reflow temperature, there is a problem that boiling or melting occurs.

[0008]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a positive electrode active material comprising a lithium-containing manganese oxide represented by LiMn2O4, which is an oxide containing movable lithium. Was. As the negative electrode,
Molybdenum oxide, lithium titanate, iron sulfide or niobium pentoxide was used as an electrode.

[0009] L which is an oxide containing mobile lithium
Lithium-containing manganese oxide or molybdenum oxide represented by iMn2O4 hardly reacts rapidly with the electrode even at the reflow temperature. Therefore, in order to make a battery capable of reflow soldering, an electrolytic solution, which is a component of the battery,
As a result of all investigations, a separator and a gasket having heat resistance and not deteriorating battery performance even in combination with an electrode were found. Thereby,
A coin-type (button-type) non-aqueous electrolyte secondary battery capable of maintaining the reflow temperature can be provided.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS By using a lithium-containing manganese oxide represented by LiMn2O4, which is an oxide containing mobile lithium, it is not necessary to add lithium to an active material in a manufacturing process. When LiMn2O4 is used as the positive electrode, the initial voltage is about 3 V, but lithium is moved to 4 V by applying a voltage (charging). When molybdenum oxide, lithium titanate, iron sulfide or niobium pentoxide is used on the negative electrode side to occlude the transferred lithium, a battery having a battery voltage of about 3 to 2 V can be manufactured.

It has been found in our experiments that when the negative electrode is made of lithium-aluminum alloy or carbon or oxide doped with lithium or electrochemically doped, an abrupt reaction occurs between the electrolyte and the negative electrode at a reflow temperature exceeding 200 ° C. Was confirmed. On the other hand, LiMn, which is an oxide previously contained by baking or the like in a synthesis step of a raw material, is used.
It was found that the lithium-containing manganese oxide represented by 2O4 did not rapidly react with the electrolyte even at the reflow temperature.

Therefore, LiM containing mobile lithium
A positive electrode active material composed of a lithium-containing manganese oxide represented by n2O4 and a negative electrode active material composed of molybdenum oxide, lithium titanate or niobium pentoxide were used as electrodes. This eliminates the need to rely on a lithium alloy unstable at the reflow temperature for lithium ions moving at the time of charging and discharging, or a carbon or oxide negative electrode contacted or electrochemically doped with lithium.

The lithium-containing manganese oxide represented by LiMn2O4 used as the positive electrode active material was an oxide containing movable lithium and was confirmed to be stable at the reflow temperature. The composition ratio of Li and Mn is 10%.
Although it is possible to change before and after, it is possible to improve cycle characteristics and the like, but using such a thing does not depart from the scope of the present invention.

Further, other elements are added to LiMn2O4,
It is possible to improve capacity and cycle characteristics.
Use of such a lithium-containing oxide does not depart from the scope of the present invention. The average particle size of the active material used in the present invention is preferably 500 μm or less, more preferably 100 μm or less, and particularly preferably 50 to 0.1 μm when used unexpectedly for reflow soldering. The form of the active material is preferably a primary particle aggregate having an average particle diameter of 1 μm to 20 μm, in which primary particles having an average particle diameter of 0.1 μm or more and 2.5 μm or less are aggregated, and particularly preferably. It is preferable to form a primary particle aggregate having an average particle size of 3.5 μm to 9.5 μm in which primary particles having an average particle size of 0.1 μm to 2.5 μm are aggregated. Further, in the primary particle aggregate, 80% or more of the total volume has a particle size of 1 micron or more.
It is preferably not more than micron, more preferably not less than 85% of the total volume, and still more preferably 90% of the total volume.
That is all. The specific surface area is preferably from 0.05 to 100 m2 / g, more preferably from 0.1 to 50 m2 / g, and particularly preferably from 0.1 to 30 m2 / g.

When used for reflow soldering, an average particle diameter of 10 μm or more and a particle diameter of 10 μm or less
Experiments have shown that it is preferable not to contain 0% or more. When the average particle diameter is 10 μm or less, or when 40% or more of particles having a particle diameter of 10 μm or less is included, the battery may suddenly react with the electrolyte to expand.

On the other hand, as the oxide used as the negative electrode active material, an oxide having an electrode potential of around 1.5 V was used. The molybdenum oxide and iron sulfide of the present invention are stable at the reflow temperature, can reversibly insert and remove lithium, and have a lower potential than the positive electrode active material. However, when iron sulfide is used, it is necessary to remove unreacted sulfur components in advance.

Molybdenum oxide MoOx can be used in the range of 2 ≦ x ≦ 3. As x is closer to 2, the potential is lower, and as x is closer to 3, the potential is higher. In recent years, a wide range of charging voltages and output voltages of batteries has been demanded according to settings on the device side of battery users. Since the battery voltage is determined by the potential difference between the positive electrode and the negative electrode, the charging voltage and the output voltage can be adjusted by changing x of molybdenum oxide MoOx, which is the negative electrode.

Although the initial capacity of the lithium titanate of the present invention is inferior to that of the anatase type titanium oxide, the cycle life is hardly deteriorated. This may be due to the difference in crystal structure.Compared with anatase-type titanium oxide, lithium titanate is easier to dope and undope lithium ions, and forms a crystal form that is less likely to be destroyed by this doping and undoping. It is estimated that there is. Lithium titanate is represented by LixTiyO4 when represented by a chemical formula, and the stoichiometric number is preferably 0.8≤x≤1.4, 16≤y≤2.2. A typical example is LiTi2O4.
In addition, Li1.33Ti1.66O4 or Li0.8Ti2.2
O4 and the like.

The lithium titanate is composed of a lithium compound such as lithium hydroxide and titanium oxide (anatase).
And firing at a temperature in the range of 500 to 1000 ° C. When X-ray diffraction was performed, it was found that the structure was titanium oxide (anatase) at 500 ° C. or lower, but the structure originated from LixTiyO 4 at 500 to 1000 ° C. It was also found that when the temperature was further increased and sintering was performed at 1000 ° C. or higher, the structure caused by LixTiyO4 changed. Preferably, a firing temperature of 700 to 950 ° C. is good.

The electrolytic solution is not particularly limited, and an organic solvent used in a conventional non-aqueous secondary battery is used.
In the organic solvent, cyclic esters, chain esters,
Cyclic ethers, chain ethers and the like are used, and specifically, propylene carbonate (PC), ethylene
Carbonate (EC), butylene carbonate (BC), vinylene carbonate, dimethyl carbonate (DM
C), diethyl carbonate (DEC), γ-butyrolactone (γBL), 2methyl-γ-butyrolactone, acetyl-γ-butyrolactone, γ-valerolactone,
1,2-dimethoxyethane (DME), 1,2-ethoxyethane, diethyl ether, ethylene glycol dialkyl ether, diethylene glycol dialkyl ether, triethylene glycol dialkyl ether, tetraethylene glycol dialkyl ether, dipropyl carbonate, methyl ethyl carbonate, methyl Butyl carbonate, methyl propyl carbonate, ethyl butyl carbonate, ethyl propyl carbonate,
Butyl propyl carbonate, alkyl propionate, dialkyl malonate, alkyl acetate, tetrahydrofuran (THF), alkyltetrahydrofuran, dialkylalkyltetrahydrofuran, alkoxytetrahydrofuran, dialkoxytetrahydrofuran, 1,3-dioxolan, alkyl-
1,3-dioxolan, 1,4-dioxolan, 2-methyltetrahydrofuran, dimethylsulfoxide,
Organic solvents such as 1,3-dioxolane, formamide, dimethylformamide, dioxolane, acetonitrile, nitromethane, methyl formate, methyl acetate, methyl propionate, ethyl propionate, phosphoric acid triester, and derivatives and mixtures thereof are preferably used. .

Further, a polymer can be used in addition to the above organic solvent. As the polymer, those conventionally used generally can be used. For example, polyethylene oxide (PEO), polypropylene oxide, crosslinked polyethylene glycol diacrylate, polyvinylidene fluoride, crosslinked polyphosphazene, polypropylene glycol diacrylate A crosslinked product, a crosslinked product of polyethylene glycol methyl ether acrylate, a crosslinked product of polypropylene glycol methyl ether acrylate, and the like are preferably used.

The main impurities present in the electrolyte (non-aqueous solvent) include water and organic peroxides (eg, glycols, alcohols, carboxylic acids).
It is considered that each of the impurities forms an insulating film on the surface of the graphitized material and increases the interfacial resistance of the electrode. Therefore, there is a possibility that the cycle life and capacity may be reduced. In addition, self-discharge during high-temperature (60 ° C. or higher) storage may increase. For this reason, it is preferable that the impurities be reduced as much as possible in the electrolytic solution containing the non-aqueous solvent. Specifically, the water content is preferably 50 ppm or less, and the organic peroxide content is preferably 1000 ppm or less.

In order to perform reflow soldering, it was found that the use of a non-aqueous solvent having a boiling point of 200 ° C. or more at normal pressure as an electrolytic solution was stable at the reflow temperature. The reflow temperature may rise to about 250 ° C., but even if γ-butyrolactone (γBL) whose boiling point at normal pressure is 204 ° C. is used, the battery may not burst even if the internal pressure of the battery rises at that temperature. Did not. In combination with the positive and negative electrodes, it was favorable to use propylene carbonate (PC), ethylene carbonate (EC), or γ-butyrolactone (γBL) alone or in combination.

As the supporting salt, lithium perchlorate (LiC
lO4), lithium hexafluorophosphate (LiPF6), lithium borofluoride (LiBF4), lithium arsenic hexafluoride (LiAsF6), lithium trifluorometasulfonate (LiCF3 SO3), lithium bistrifluoromethylsulfonylimide [LiN (CF3 SO2)
2] and one or more salts such as lithium salts (electrolytes) such as thiocyanate salts and aluminum fluoride salts. The amount dissolved in the non-aqueous solvent is desirably 0.5 to 3.0 mol / 1.

To perform reflow soldering, use LiCl
Lithium hexafluorophosphate (LiPF6), lithium borofluoride (LiBF4), and lithium trifluorometasulfonate (LiCF3 SO3), which are more fluorine-containing supporting salts than chlorine-based ones such as O4, are thermally It was stable in characteristics. A solid electrolyte used by mixing a polymer and a supporting salt is produced by a solvent removal method or the like. In this method, a polymer and a supporting salt are dissolved in acetonitrile, 1,2-dimethoxyethane, or the like, and then applied to the separator of the present invention and dried. There is also a method in which polypyrrole is dispersed in a solution in which PEO and a supporting salt are dissolved, and the solvent is removed. Complex (POE) having methacrylate ester as skeleton
-PMMA), a mixture of a monomer and a supporting salt can be polymerized by heating or light irradiation.

As the separator, an insulating film having a high ion permeability, a predetermined mechanical strength, and an insulating film is used. For reflow soldering, glass fiber can be used most stably.
Resins such as polyphenylene sulfide, polyethylene terephthalate, polyamide, and polyimide at a temperature of at least ° C can also be used. The pore size of the separator is in a range generally used for batteries. For example, 0.0
1 to 10 μm is used. The thickness of the separator is, for example, 5 to 300 μm, which is generally used in the range for batteries.

A gasket is usually made of polypropylene or the like, but when performing reflow soldering, a resin having a heat deformation temperature of 230 ° C. or higher is made of polyphenylene sulfide,
Polyethylene terephthalate and polyamide did not rupture at the reflow temperature, and there was no problem such as liquid leakage due to deformation of the gasket during storage after reflow.

In addition, polyetherketone resin, polyetheretherketone resin, polyarylate resin, polybutyleneterephthalate resin, polycyclohexanedimethyleneterephthalate resin, polyethersulfone resin, polyaminobismaleimide resin, polyetherimide resin are used. it can. Further, it has been found through experiments that glass fibers, my whiskers, ceramic fine powder and the like are added to this material in an amount of about 10% by weight or less, and the same effect as in this experiment is exhibited. .

When the shape of the electrode is a coin or button, the mixture of the positive electrode active material and the negative electrode active material is compressed into a pellet and used. In the case of a thin coin or button, a sheet-shaped electrode may be punched and used. The thickness and diameter of the pellet are determined by the size of the battery. As a method for pressing the pellets, a method generally used can be used, but a die pressing method is particularly preferable. The pressing pressure is not particularly limited.
5 t / cm2 is preferred. Press temperature is from room temperature to 200 ℃
Is preferred.

A conductive agent, a binder, a filler, and the like can be added to the electrode mixture. The type of the conductive agent is not particularly limited and may be a metal powder, but a carbon-based one is particularly preferable. The most common carbon materials are natural graphite (scale graphite, flake graphite, earth graphite, etc.), artificial graphite, carbon black, channel black, thermal black, furnace black, acetylene black, carbon fiber, and the like. As the metal, metal powder such as copper, nickel, and silver, and metal fibers are used. Conducting polymers are also used.

The amount of carbon to be added is not particularly limited, although the mixing ratio varies depending on the electric conductivity of the active material, the shape of the electrode, and the like, but is preferably 1 to 50% by weight, more preferably 2 to 40% by weight in the case of a negative electrode. The average particle size of carbon is 0.5 to 50μ
m, preferably in the range of 0.5 to 15 μm, more preferably in the range of 0.5 to 6 μm, the contact between the active materials is improved, the formation of a network of electron conduction is improved, and the electrochemical Active materials that do not participate in the reaction are reduced.

The binder is preferably insoluble in the electrolytic solution, but is not particularly limited. Usually, polyacrylic acid and neutralized polyacrylic acid, polyvinyl alcohol, carboxymethyl cellulose, starch, hydroxypropyl cellulose, regenerated cellulose, diacetyl cellulose, polyvinyl chloride, polyvinyl pyrrolidone, tetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, ethylene -Polysaccharides such as propylene-diene polymer (EPDM), sulfonated EPDM, styrene butadiene rubber, polybutadiene, fluoro rubber, polyethylene oxide, polyimide, epoxy resin, phenol resin, thermoplastic resin, thermosetting resin, and rubber elasticity A polymer or the like is used as one type or a mixture thereof. The amount of the binder added is not particularly limited, but is preferably 1 to 50% by weight.

As the filler, any fibrous material that does not cause a chemical change in the constructed battery can be used. In the case of the present invention, fibers such as carbon and glass are used. The amount of the filler is not particularly limited,
0-30% by weight is preferred. As the current collector of the electrode active material, a metal plate having a small electric resistance is preferable. For example, for the positive electrode, in addition to materials such as stainless steel, nickel, aluminum, titanium, tungsten, gold, platinum, and calcined carbon, carbon on the surface of aluminum or stainless steel,
What processed nickel, titanium, or silver is used. For stainless steel, duplex stainless steel is effective against corrosion. In the case of coins and button batteries, nickel plating is performed on the outside of the battery. Processing methods include wet plating, dry plating, CVD, PVD,
Cladding by pressure bonding, coating and the like.

For the negative electrode, stainless steel, nickel, copper, titanium, aluminum, tungsten, gold,
In addition to platinum, calcined carbon, and the like, those obtained by treating the surface of copper or stainless steel with carbon, nickel, titanium, or silver, an Al—Cd alloy, or the like is used. Examples of the processing method include wet plating, dry plating, CVD, PVD, cladding by pressure bonding, coating, and the like.

It is also possible to fix the electrode active material and the current collector with a conductive adhesive. As the conductive adhesive, a resin obtained by adding carbon or metal powder or fiber to a resin dissolved in a solvent, a conductive polymer dissolved, or the like is used. In the case of a pellet-shaped electrode, it is applied between the current collector and the electrode pellet to fix the electrode. In this case, the conductive adhesive often contains a thermosetting resin.

In the case of coins and button batteries, a sealant of one or a mixture of asphalt pitch, butyl rubber, fluorinated oil, chlorosulfonated polyethylene, epoxy resin and the like is used between the gasket and the positive and negative electrode cans. When the sealant is transparent, it is colored to clarify the presence or absence of application. Examples of the method of applying the sealant include injection of the sealant into the gasket, application to the positive and negative electrode cans, dipping of the gasket into the sealant solution, and the like.

The non-aqueous electrolyte secondary battery of the present invention is used for:
Although not particularly limited, for example, there are a backup power supply for a mobile phone and a pager, a power supply for a wristwatch having a power generation function, and the like. The battery of the present invention is desirably assembled in a dehumidified atmosphere or an inert gas atmosphere. It is also preferable that the parts to be assembled are dried in advance. As a method for drying or dehydrating the pellets, sheets and other parts, a generally employed method can be used. In particular, it is preferable to use hot air, vacuum, infrared rays, far-infrared rays, electron beams and low-humidity air alone or in combination. The temperature is preferably in the range of 80 to 350 ° C, particularly 100 to 2 ° C.
A range of 50 ° C. is preferred. The water content is 200
It is preferably 0 ppm or less, and in the case of the positive electrode mixture, the negative electrode mixture and the electrolyte, each is preferably 50 ppm or less from the viewpoint of improving the charge / discharge cycle property.

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

[0039]

EXAMPLE In this example, a lithium-containing manganese oxide was used as the positive electrode active material and MoO2 was used as the negative electrode active material. The positive electrode, the negative electrode, and the electrolyte prepared as described below were used. The size of the battery was 6.8 mm in outer diameter and 2.1 mm in thickness. A cross-sectional view of the battery is shown in FIG.

In Example 1, a positive electrode was manufactured as follows. Commercially available pulverized LiMn2O4 is mixed with graphite as a conductive agent and polyacrylic acid as a binder in a weight ratio of LiMn2O4: graphite: polyacrylic acid = 88.5: 9: 2.5 in a positive electrode mixture. Then, this positive electrode mixture was coated at 2 ton / cm 2 with a diameter of 4.0.
It was pressed into 5 mm pellets. Thereafter, the positive electrode pellet 101 obtained in this manner is combined with the positive electrode case 1 using an electrode current collector 102 made of a conductive resin adhesive containing carbon.
After bonding and integrating with each other, the resultant was dried by heating under reduced pressure at 150 ° C. for 8 hours.

The negative electrode was manufactured as follows. Commercial M
The pulverized oO2 was used as the active material of the working electrode.
Graphite as a conductive agent and polyacrylic acid as a binder were added to the active material in a weight ratio of 70.5: 21.
The mixture was mixed at a ratio of 5: 7 to obtain a negative electrode mixture. 2t mixture
It was used that was formed into a pellet having a diameter of 4.05 mm at a pressure of on / cm 2. Thereafter, the thus obtained negative electrode pellet 104 is used as the negative electrode case 10 by using an electrode current collector 2 made of a conductive resin adhesive using carbon as a conductive filler.
5, and then dried by heating under reduced pressure at 150 ° C. for 8 hours.

Electrolyte solution 20 was prepared by dissolving 1 mol / l of LiClO 4 in a mixed solvent of PC, EC, and DME at a volume ratio of 1: 1: 2, and was sealed in a battery can. The gasket 108 used was made of polyphenylene sulfide. In the same manner, a sample using another active material, an electrolytic solution, and a battery member was prepared and evaluated.

The results are shown in Table 1. In Table 1, ◎ indicates good properties, は indicates no practical problem, and Δ indicates good properties.
Indicates that the battery has a slight swelling and a rise in internal resistance, ×
Has a problem in characteristics and is not at a practical level. table 1
2 shows charge / discharge curves of Example 1, FIG. 3 shows Example 2, FIG. 4 shows Example 3, and FIG. 5 shows Example 4. Charge: 100 μA constant current, 3.0 V, constant voltage hold for 24 hours, discharge: 50 μA constant current, end voltage 0.8
V.

[0044]

[Table 1]

From the results shown in Table 1 and FIGS. 2 to 5,
The non-aqueous electrolyte secondary battery in which the positive electrode active material is composed of a lithium-containing manganese oxide represented by LiMn2O4 and the negative electrode active material is selected from molybdenum dioxide, lithium titanate or niobium pentoxide has good results in terms of capacity and cycle characteristics. showed that. In performing reflow soldering, propylene carbonate (PC), ethylene carbonate (EC), γ-butyrolactone (γB
L) and lithium hexafluorophosphate (L
Good results were obtained when an electrolyte selected from iPF6), lithium borofluoride (LiBF4), and lithium trifluorometasulfonate (LiCF3 SO3) was used.

For molybdenum oxide (MoOx), x
Experiments were performed in which was changed. (1) MoO2 A commercial grade reagent was used as it was. (2) MoO2.5 After mixing using a mortar at a ratio of MoO2: MoO3 = 1: 1, the mixture was baked in nitrogen at 700 ° C. for 12 hours. (3) MoO2.66 MoO2: MoO3 = 1: 2 was fired under the same conditions as above. (4) MoO2.75 MoO2: MoO3 = 1: 3 was fired under the same conditions as above. (5) MoO3 A commercially available special-grade reagent was used as it was.

The characteristics of these molybdenum oxides as electrodes were examined. Each molybdenum oxide was pulverized, and graphite was mixed as a conductive agent, and polyacrylic acid was mixed as a binder at a weight ratio of 45:40:15 to prepare an electrode mixture. This mixture was pressed into pellets having a diameter of 4.05 mm at 2 ton / cm 2. afterwards,
The pellets thus obtained were bonded and integrated with a positive electrode case using an electrode current collector made of a conductive resin adhesive containing carbon as a conductive filler, and then dried by heating at 150 ° C. for 8 hours under reduced pressure.

On the other hand, the negative electrode was produced by press-bonding a lithium foil to a negative electrode case. The electrolyte is PC, E
C, DME volume ratio 1: 1: 2 LiClO4 mixed solvent
Was dissolved in 1 mol / l and sealed in a battery can. Thus, a battery for measuring electrode characteristics was manufactured. The respective characteristics are shown in FIGS. The figure shows the charge and discharge characteristics of the first cycle and the third cycle.

Molybdenum oxide (MoOx) tends to increase in potential and increase in capacity as x increases. The cycle property was relatively good when x was small.
Since the battery voltage is determined by the potential difference between the positive electrode and the negative electrode, when the battery is combined with a 4V-based electrode such as LiMn2O4, the battery voltage increases when x is reduced, and decreases when x is increased. Molybdenum oxide (MoOx)
By changing x in (1), it is possible to finely respond to diversifying demands for voltage of battery-powered devices. x
The battery in the case of = 2 is as shown in FIG.
Even when a battery was manufactured using molybdenum oxide other than x = 2, the same effect as MoO2 where x = 2 could be confirmed.

[0050]

As described in detail above, the present invention relates to a positive electrode active material comprising a lithium-containing manganese oxide represented by LiMn2O4, which is an oxide containing mobile lithium;
By using a negative electrode composed of molybdenum oxide, lithium titanate, or niobium pentoxide as the negative electrode, metal lithium, which was complicated in handling, does not have to be used in the manufacturing process of assembly.

Further, since lithium-containing manganese oxide and molybdenum oxide represented by LiMn2O4, which is an oxide containing mobile lithium, hardly reacts rapidly with the electrode even at the reflow temperature, the electrolytic solution which is a component of the battery is used. ,
By combining a separator and a gasket having heat resistance, a coin-type (button-type) non-aqueous electrolyte secondary battery capable of maintaining the reflow temperature could be provided.

Further, it was found that the potential of molybdenum oxide (MoOx) tends to increase as x increases. Since the battery voltage is determined by the potential difference between the positive electrode and the negative electrode, when combining MoOx with a 4V-based electrode of LiMn2O4 in an actual battery, decreasing x decreases the battery voltage and increasing x increases the battery voltage. This allows
It is possible to respond to the diversifying demands for battery-powered equipment in detail.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a coin-type lithium secondary battery of the present invention.

FIG. 2 Charges a coin-type lithium secondary battery using lithium-containing manganese oxide LiMn2O4 as a positive electrode active material and MoO2 as a negative electrode active material: 100 μA constant current;
0V, constant voltage holding for 24 hours, discharging: 50 μA constant current, charge / discharge characteristics when performed at final voltage 0.8V.

FIG. 3 Charges a coin-type lithium secondary battery using lithium-containing manganese oxide LiMn2O4 as a positive electrode active material and Li4Ti5O12 as a negative electrode active material: 100 μA constant current, 3.0 V, constant voltage hold for 24 hours, discharge: 50 μA
Charging / discharging characteristics at a constant current and a final voltage of 0.8 V.

FIG. 4 shows charging of a coin-type lithium secondary battery using lithium-containing manganese oxide LiMn2O4 as a positive electrode active material and Nb2O5 as a negative electrode active material: 100 μA constant current;
3.0 V, 24 hours constant voltage holding, discharging: 50 μA constant current, charge / discharge characteristics when performed at a final voltage of 2.0 V.

FIG. 5: Charging a coin-type lithium secondary battery using lithium-containing manganese oxide LiMn2O4 as a positive electrode active material and FeS as a negative electrode active material: 100 μA constant current, 3.0
V, constant voltage hold for 24 hours, discharge: charge / discharge characteristics when performed at a constant current of 50 μA and a final voltage of 0.8 V.

FIG. 6: Electrode characteristics of MoO2

FIG. 7: Electrode characteristics of MoO2.5

FIG. 8: Electrode characteristics of MoO 2.66

FIG. 9 shows electrode characteristics of MoO 2.75.

FIG. 10: Electrode characteristics of MoO3

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 101 Positive electrode pellet 102 Electrode current collector 103 Positive electrode case 104 Negative electrode pellet 105 Negative electrode case 106 Lithium foil 107 Electrolyte 108 Gasket 109 Separator

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Tsugio Sakai 1-8-8 Nakase, Mihama-ku, Chiba-shi, Chiba F-term (reference) in Seiko Instruments Inc. 5H014 AA02 AA06 EE01 EE10 HH00 HH01 HH06 HH08 5H029 AJ05 AJ12 AJ14 AK03 AL02 AL03 AL04 AM02 AM03 AM04 AM05 AM07 BJ03 DJ03 DJ04 DJ15 EJ06 EJ12 HJ02 HJ05 HJ14 HJ15

Claims (5)

[Claims] 1. A non-aqueous electrolyte battery comprising a positive electrode, a negative electrode, a non-aqueous solvent, an electrolyte containing a supporting salt, a separator, and a gasket member, wherein the positive electrode active material comprises a lithium-containing manganese oxide represented by LiMn 2 O 4, A non-aqueous electrolyte secondary battery, wherein the negative electrode active material comprises at least one compound selected from molybdenum oxide, lithium titanate, iron sulfide, and niobium pentoxide. 2. The lithium titanate in use of the nonaqueous electrolyte secondary battery is represented by the general formula LixTiyO4, wherein 0.8 ≦ x ≦ 1.4, 1.6 ≦ y ≦ 2.2.
The non-aqueous electrolyte secondary battery according to claim 1, wherein 3. The active material used for the positive electrode or the negative electrode has an average particle size of 10 μm or more, does not contain 40% or more of particles having a particle size of 10 μm or less, and has a boiling point of 200% at normal pressure of the non-aqueous solvent. C. or more, and the supporting salt contains fluorine, and the separator is made of glass fiber or a resin having a heat deformation temperature of 230 ° C. or more, and the gasket is made of a resin having a heat deformation temperature of 230 ° C. or more. The non-aqueous electrolyte secondary battery according to claim 1. 4. The non-aqueous solvent is a single or complex selected from propylene carbonate (PC), ethylene carbonate (EC) and γ-butyrolactone (γBL), and the supporting salt is lithium hexafluorophosphate. (Li
PF6), lithium borofluoride (LiBF4), lithium trifluorometasulfonate (LiCF3SO3) alone or in combination, and the resin is at least one resin selected from polyphenylene sulfide, polyethylene terephthalate, polyamide, and polyimide The non-aqueous electrolyte secondary battery according to claim 1, wherein 5. The molybdenum oxide has a general formula of MoOx.
The non-aqueous electrolyte secondary battery according to claim 1, wherein 2 ≦ x ≦ 3.