JPH11135152A - Nonaqueous electrolyte secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nonaqueous electrolyte secondary battery with long storage life and high capacity. SOLUTION: In a sealed nonaqueous electrolyte secondary battery formed by pouring a nonaqueous electrolyte containing a lithium salt in a battery container, then sealing the battery container, the content of free acid contained in the nonaqueous electrolyte is controlled so as not to exceed 300 ppm three years after sealing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-capacity sealed non-aqueous electrolyte secondary battery having improved storage stability.

[0002]

2. Description of the Related Art In recent years, with the spread of portable electronic devices such as notebook personal computers and mobile phones, the use of lithium-ion secondary batteries having a higher capacity than conventional nickel-cadmium batteries or nickel-metal hydride batteries has been rapidly increasing. Is growing.

[0003] The usage time of a portable electronic device that can be used by one charge is gradually increasing due to an increase in the capacity of a battery. On the other hand, the secondary battery is gradually deteriorated due to repeated charging and discharging due to an electrochemical reaction, and thus has a limitation in long-term use. For this reason, some portable devices recommend that the battery pack be replaced with a new one within about one year from the start of use of the battery pack. Portable electronic devices are being replaced by new models in about three years at the earliest due to remarkable progress. It is desirable that the batteries mounted on these devices have the same life as the devices. Causes of the deterioration of the secondary battery over time are the collapse of the electrode material structure due to repeated charge and discharge, the decomposition of the electrolyte in the severe redox state at the electrode interface, and the intrusion of moisture from the sealing part during and after battery assembly. The effects of the While development of electrode materials with good storability and selection of appropriate electrolytes are performed,
Attempts have been made to reduce the amount of water in the battery.
In particular, the presence of moisture is not preferable because it decomposes the lithium salt in the electrolyte, and moisture management in the battery assembly process is important. For example, the positive and negative electrode sheets are usually subjected to a heat treatment before assembling the battery so that sufficient dehydration is performed. Also, the battery assembling material such as a battery can is dehydrated before being put on the assembling process. Further, the electrolyte is also produced using the dehydrated raw material, and the dehydration is usually repeated until the battery is assembled.
However, in the past, even with such sufficient dehydration, deterioration with time may occur during storage, and the cause thereof has not been elucidated, and there has been a long-awaited solution to this point.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a non-aqueous electrolyte secondary battery having excellent storage stability and high capacity.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a sealed non-aqueous electrolyte secondary battery using a non-aqueous electrolyte containing a lithium salt. This was achieved by a non-aqueous electrolyte secondary battery in which the amount of acid was not more than a predetermined amount. That is, the present invention provides (1) a sealed non-aqueous electrolyte secondary battery which is sealed after injection of a non-aqueous electrolyte containing a lithium salt, after three years after sealing.
Non-aqueous electrolyte secondary battery, characterized in that the amount of free acid contained in the non-aqueous electrolyte is not more than 300 ppm,
(2) The non-aqueous electrolyte secondary battery according to (1), wherein the lithium salt contained in the non-aqueous electrolyte is a lithium salt containing fluorine. (3) Free lithium contained in the non-aqueous electrolyte The nonaqueous electrolyte secondary battery according to (1) or (2), wherein the acid is hydrogen fluoride, and (4) the gasket used for the sealing portion is heat-treated after molding. (1) The non-aqueous electrolyte secondary battery according to (1), (2) or (3), (5) the amount of free acid contained in the non-aqueous electrolyte before being injected into the battery can is 100 ppm or less. The nonaqueous electrolyte secondary battery according to any one of (1) to (4), wherein (6) the electrode group before insertion into the battery can has a water content of 300 ppm or less. The non-aqueous electrolyte according to any one of (1) to (5), (1) to (6), wherein the battery and the (7) environment in which the electrode group is inserted into the battery can, the electrolyte is injected, and the environment at the time of closing the battery can are controlled to a dew point of -50 ° C or less. A non-aqueous electrolyte secondary battery according to any one of the above.

[0006] In the present invention, the free acid refers to an acid detected from an electrolytic solution, and an acid originally contained in the electrolytic solution,
It refers to the total amount of acid inside the battery that is extracted by the electrolyte or its vapor and consequently detected from the electrolyte. The free acid is
When the battery is built into the battery as an acid at the time of battery assembly,
It may be generated by a chemical reaction, for example, hydrogen fluoride. Further, three years after sealing means that the battery is assembled and sealed and stored for three years under a normal environment (normally, a temperature of 10 to 35 ° C.). After sealing, the battery may be subjected to an aging treatment, a charge / discharge treatment, a charge / discharge cycle, and a combination thereof, if necessary.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be described below in detail. The non-aqueous electrolyte secondary battery of the present invention, after manufacturing positive and negative electrode sheets, laminating separators, inserting the wound spiral electrode group into a battery can, sealing the electrolyte after injecting the electrolyte, and then performing an appropriate aging treatment. Do it. Although the above description has been made with reference to a cylindrical battery, the present invention is not limited to a cylindrical battery, but is applicable to any sealed battery such as a square battery. The non-aqueous electrolyte secondary battery of the present invention is a battery characterized in that the amount of free acid contained in the non-aqueous electrolyte does not exceed 300 ppm after three years from closure. The amount of the free acid is preferably as small as 300 ppm or less.
m or less, more preferably 150 ppm or less. The effect of a free acid generated or present in a trace amount in a non-aqueous electrolyte secondary battery has not been previously known. The amount of free acid can be determined by disassembling the battery and quantifying the amount of hydrogen fluoride contained in the electrolyte. The amount of hydrogen fluoride was determined by using bromthymol blue as an indicator and determining the amount of hydrogen fluoride.
It can be measured by neutralization titration using a 1N NaOH aqueous solution. The moisture was measured using a commercially available Karl Fischer moisture meter (eg, MKC-2 manufactured by Kyoto Electronics).
10 Karl Fischer moisture meter).

In order to suppress the amount of free acid generated in three years after the sealing, it is necessary to sufficiently dehydrate the constituent materials of the battery inserted into the battery can before the sealing and to increase the degree of sealing of the battery by the sealing. is there. The gasket for sealing used in the present invention is one in which distortion at the time of sealing is removed by annealing (heat treatment) after molding. The material of the gasket that can be used in the present invention is an olefin-based polymer, a fluorine-based polymer, a polyester, a cellulosic-based polymer, a polyimide, or a polyamide.From the organic solvent resistance and low moisture permeability, the olefin-based polymer and polyester are preferable. Particularly, polypropylene, a block copolymer of propylene and ethylene, and polybutylene terephthalate are preferred. The gasket used in the non-aqueous electrolyte secondary battery of the present invention is formed into a shape that can be swaged together with a sealing member such as a terminal cap or a safety valve, and then heat-treated. If the heat treatment is not sufficient, deformation occurs gradually after caulking, which causes a reduction in the degree of sealing. The temperature of the heat treatment is preferably from 60 to 130C, more preferably from 80 to 120C, and particularly preferably from 90 to 110C. The heat treatment time is preferably from 10 minutes to 5 hours, particularly preferably from 20 minutes to 2 hours.

The non-aqueous electrolyte used in the non-aqueous electrolyte secondary battery of the present invention preferably contains 100 ppm or less of free acid before being injected into a battery can. A more preferred amount of free acid is 60 ppm or less, and particularly preferred is 4 ppm.
It is 0 ppm or less. In order to make an electrolyte solution with a small amount of water and free acid, it is necessary to repeat the distillation, or to use a dehydrating agent such as molecular sieve to sufficiently dehydrate the electrolytic solvent and to use a high-purity supporting salt. is necessary. The preparation of the electrolytic solution is preferably performed in dry air having a dew point of minus 50 ° C. or less or in an inert gas.
The prepared electrolyte may be further dehydrated.

The electrolyte generally comprises a supporting salt and a solvent. As a supporting salt in a lithium secondary battery, a lithium salt is mainly used. Examples of the lithium salt that can be used for the nonaqueous electrolyte secondary battery of the present invention include LiClO ₄ , L
iBF ₄ , LiPF ₆ , LiCF ₃ CO ₂ , LiAsF
_{6, LiSbF 6, LiB 10 Cl} 10, LiOSO 2 C n
Fluorosulfonic acid represented by F _{2n + 1} (n is a positive integer of 6 or less), LiN (SO ₂ C _n F _{2n + 1} ) (SO ₂ C _m F
_{2m + 1} represented by imide salt) (m, n are each 6 or less positive _{integer), LiN (SO 2 C p} F 2p + 1) (SO 2 C q
F _{2q + 1} ) (SO ₂ C _r F _{2r + 1} ) methide salt (p, q, and r are each a positive integer of 6 or less), lithium lower aliphatic carboxylate, LiAlCl ₄ , LiCl, L
Li salts such as iBr, LiI, lithium chloroborane, lithium tetraphenylborate, and the like can be given, and one kind or a mixture of two or more kinds can be used. Among them, those in which LiBF ₄ and / or LiPF ₆ are dissolved are preferable. The concentration of the supporting salt is not particularly limited, but is preferably 0.2 to 3 mol per liter of the electrolytic solution.

Solvents that can be used in the non-aqueous electrolyte secondary battery of the present invention include propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, γ-butyrolactone, methyl formate, methyl acetate,
1,2-dimethoxyethane, tetrahydrofuran, 2-
Methyltetrahydrofuran, dimethylsulfoxide,
1,3-dioxolan, formamide, dimethylformamide, dioxolan, dioxane, acetonitrile,
Aprotic such as nitromethane, ethyl monoglyme, phosphoric acid triester, trimethoxymethane, dioxolane derivative, sulfolane, 3-methyl-2-oxazolidinone, propylene carbonate derivative, tetrahydrofuran derivative, ethyl ether, 1,3-propane sultone Organic solvents can be mentioned, and one kind or a mixture of two or more kinds can be used. Of these, carbonate-based solvents are preferable, and it is particularly preferable to use a mixture of a cyclic carbonate and a non-cyclic carbonate. As the cyclic carbonate, ethylene carbonate and propylene carbonate are preferable. As the acyclic carbonate, diethyl carbonate, dimethyl carbonate, and methyl ethyl carbonate are preferable.

[0012] Examples of the electrolyte that can be used in the nonaqueous electrolyte secondary battery of the present invention include LiCF ₃ SO ₃ , an electrolyte obtained by appropriately mixing ethylene carbonate, propylene carbonate, 1,2-dimethoxyethane, dimethyl carbonate or diethyl carbonate. LiClO ₄ , LiBF ₄
And / or an electrolyte containing LiPF ₆ is preferred. Particularly, a mixed solvent of at least one of propylene carbonate or ethylene carbonate and at least one of dimethyl carbonate or diethyl carbonate,
An electrolyte containing LiPF ₆ and at least one salt selected from iCF ₃ SO ₃ , LiClO ₄ , or LiBF ₄ is preferable. The amount of these electrolytes added to the battery is not particularly limited, and can be used according to the amounts of the positive electrode material and the negative electrode material and the size of the battery.

Further, in addition to the electrolytic solution, the following solid electrolyte can be used in combination. Solid electrolytes are classified into inorganic solid electrolytes and organic solid electrolytes. Well-known inorganic solid electrolytes include nitrides, halides, and oxyacid salts of Li. Among them, Li ₃ N, LiI, Li _{5
NI 2, Li 3 N-LiI} -LiOH, Li 4 SiO
_{4, Li 4 SiO 4 -LiI-} LiOH, x Li 3 PO
_{4 - (1-x) Li} 4 SiO 4, Li 2 SiS 3, it is effective such as phosphorus sulfide compound (where 0 <x ≦ 1).

In the organic solid electrolyte, a polyethylene oxide derivative or a polymer containing the derivative, a polypropylene oxide derivative or a polymer containing the derivative, a polymer containing an ion dissociating group, a mixture of a polymer containing an ion dissociating group and the above aprotic electrolyte solution , A phosphate matrix polymer, and a polymer matrix material containing an aprotic polar solvent are effective. Furthermore, there is a method of adding polyacrylonitrile to the electrolytic solution. In addition, a method of using an inorganic and an organic solid electrolyte in combination is also known.

Further, another compound may be added to the electrolyte for the purpose of improving the discharge and charge / discharge characteristics. For example, pyridine, pyrroline, pyrrole, triphenylamine, phenylcarbazole, triethylphosphite, triethanolamine, cyclic ether, ethylenediamine,
Hexaphosphoric acid triamide, nitrobenzene derivative, sulfur, quinone imine dye, N-substituted oxazolidinone and N, N'-substituted imidalidinone, glymes such as ethylene glycol dialkyl ether, quaternary ammonium salt, polyethylene glycol, pyrrole, 2-methoxyethanol , AlCl ₃ , monomer of conductive polymer electrode active material, triethylene phosphoramide, trialkylphosphine, morpholine, aryl compound having carbonyl group, crown ethers such as 12-crown-4, hexamethylphosphoric triamide And 4-alkylmorpholines, bicyclic tertiary amines, oils, quaternary phosphonium salts, tertiary sulfonium salts, and the like. Particularly preferred is a case where triphenylamine and phenylcarbazole are used alone or in combination.

Further, in order to make the electrolyte nonflammable, a halogen-containing solvent such as carbon tetrachloride or ethylene trifluoride can be contained in the electrolyte. In addition, carbon dioxide gas can be included in the electrolytic solution in order to provide suitability for high-temperature storage.

The entire amount of the electrolytic solution may be injected at one time, but it is preferable to inject it in two or more portions. In the case of injecting two or more times, even if each liquid has the same composition, different compositions (for example, after injecting a non-aqueous solvent or a solution in which a lithium salt is dissolved in a non-aqueous solvent, a non-aqueous solution having a higher viscosity than the solvent) A solution in which a lithium salt is dissolved in a solvent or a non-aqueous solvent is injected). Further, in order to shorten the injection time of the electrolyte solution, the pressure of the battery can may be reduced, or a centrifugal force or an ultrasonic wave may be applied to the battery can.

The electrode group of the non-aqueous electrolyte secondary battery of the present invention comprises:
The amount of water contained in the electrode group before being inserted into the battery can is 300
It is preferably at most ppm. It is more preferably at most 200 ppm, particularly preferably at most 100 ppm. Materials constituting the battery other than the electrode group, for example, a battery can or an insulating plate,
It is preferable that a sealing member such as a gasket is sufficiently dehydrated before assembling the battery. These members are preferably washed with a suitable solvent or the like, and then stored in dry air or an inert gas having a dew point of −50 ° C. or less.

The electrode sheet after application is dried and dehydrated by the action of hot air, vacuum, infrared rays, far infrared rays, electron beams and low humidity air. These methods can be used alone or in combination. The drying temperature is preferably in the range of 50 to 350 ° C. More specifically, after pressing an electrode sheet dried at 50 to 100 ° C., heat-treating at 150 to 260 ° C., cutting the electrode into a usable width, and further dehydrating at 160 to 250 ° C. before battery assembly. Is preferred. The heat treatment is particularly preferably performed at a temperature of 190 to 250 ° C. for 2 minutes to 2 hours.
It is particularly preferred to carry out the treatment at a temperature of ° C. for 20 minutes to 10 hours. The water content of the electrode immediately before battery assembly is 200 pp
m or less, and particularly preferably 100 ppm or less.

In the manufacture of the non-aqueous electrolyte secondary battery of the present invention, the assembly environment of the battery is controlled to a dew point of −50 ° C. or less through the steps of inserting the electrode group into the battery can, injecting the electrolyte, and sealing the battery can. It is preferred that

The positive electrode (or negative electrode) used in the non-aqueous electrolyte secondary battery of the present invention can be produced by applying a positive electrode mixture (or negative electrode mixture) on a current collector and molding. The positive electrode mixture (or negative electrode mixture) may include a conductive agent, a binder, a dispersant, a filler, an ionic conductive agent, a pressure enhancer, and various additives in addition to the positive electrode active material (or the negative electrode material). it can. These electrodes may be in the form of a disk or a plate, but are preferably in the form of a flexible sheet.

Hereinafter, the materials used for the electrode mixture of the non-aqueous electrolyte secondary battery of the present invention will be described. The positive electrode active material used in the nonaqueous electrolyte secondary battery of the present invention is preferably a lithium-containing transition metal oxide. Lithium-containing transition metal oxides include Ti, V, Cr, Mn, Fe, Co, Ni, M
An oxide mainly containing lithium and at least one transition metal element selected from o and W, and a compound having a molar ratio of lithium to the transition metal of 0.3 to 2.2. More preferably, V, Cr, Mn, Fe, Co, N
An oxide mainly containing lithium and at least one transition metal element selected from i, and a compound having a molar ratio of lithium to the transition metal of 0.3 to 2.2. In addition, Al, Ga, In, Ge, Sn, Pb, S
b, Bi, Si, P, B, etc. may be contained. More preferred lithium-containing transition metal oxides are Li _x C
oO ₂ , Li _x NiO ₂ , Li _x MnO ₂ , Li _x Co
_a Ni _1-a O ₂ , Li _x Co _b V _1-b O _z , Li _x Co
_{b Fe 1-b O 2,} Li x Mn 2 O 4, Li x Mn c Co
_{2-c O 4, Li x} Mn c Ni 2-c O 4, Li x Mn c V
_{2-c O 4, Li x} Mn c Fe 2-c O 4 ( wherein x = 0.
02-1.2, a = 0.1-0.9, b = 0.8-0.
98, c = 1.6-1.96, z = 2.01-2.3)
It is. Most preferred lithium-containing transition metal oxides include Li _x CoO ₂ , Li _x NiO ₂ , and Li _x MnO ₂
, Li _x Co _a Ni _1-a O ₂ , Li _x Mn ₂ O ₄ , L
_{i x Co b V 1-b} O z (x = 0.02~1.2, a =
0.1-0.9, b = 0.9-0.98, z = 2.01
To 2.3). The value of x is a value before the start of charge / discharge, and increases / decreases due to charge / discharge.

The positive electrode active material used in the nonaqueous electrolyte secondary battery of the present invention can be synthesized by a method of mixing and firing a lithium compound and a transition metal compound or a solution reaction.
Particularly, a firing method is preferable. Details of firing are described in
These methods are described in paragraph 35 of 60867, JP-A-7-14579 and the like.
The positive electrode active material obtained by firing may be used after being washed with water, an acidic aqueous solution, an alkaline aqueous solution, or an organic solvent. Further, as a method of chemically inserting lithium ions into the transition metal oxide, a method of synthesizing lithium metal, a lithium alloy, or butyllithium by reaction with the transition metal oxide may be used.

The average particle size of the positive electrode active material used in the nonaqueous electrolyte secondary battery of the present invention is not particularly limited.
~ 50 μm is preferred. It is preferable that the volume of the particles of 0.5 to 30 μm is 95% or more. More preferably, the volume occupied by the particle group having a particle size of 3 μm or less is 18% or less of the total volume, and the volume occupied by the particle group having a particle size of 15 μm or more and 25 μm or less is 18% or less of the total volume. Although the specific surface area is not particularly limited, it is 0.01 to 5 by the BET method.
0 m ² / g are preferred, 0.2m ² / g~1m ² /
g is preferred. Also, 5 g of the positive electrode active material was added to 100 ml of distilled water.
The pH of the supernatant when dissolved in water is preferably 7 or more and 12 or less.

When the positive electrode active material of the nonaqueous electrolyte secondary battery of the present invention is obtained by firing, the firing temperature is 500 to 1
The temperature is preferably 500 ° C, more preferably 70 ° C.
0 to 1200 ° C., particularly preferably 750 to 100 ° C.
0 ° C. The firing time is preferably 4 to 30 hours, more preferably 6 to 20 hours, and particularly preferably 6 to 15 hours.

The negative electrode material used in the non-aqueous electrolyte secondary battery of the present invention may be any compound capable of inserting and extracting lithium ions. Examples of such a negative electrode material include lithium metal, a lithium alloy, a carbonaceous compound, an inorganic oxide, an inorganic chalcogen compound, a metal complex, and an organic polymer compound. These may be used alone or in combination.

Among the above-mentioned negative electrode materials, carbonaceous materials, oxides of metals or metalloids, and chalcogens are preferred. The carbonaceous material is a material substantially composed of carbon, for example, petroleum pitch, natural graphite, artificial graphite, non-graphitizable carbon, mesocarbon microbeads, PAN-based carbon fiber, cellulose-based carbon fiber, pitch-based carbon fiber, Vapor-grown carbon fiber, dehydrated PVA-based carbon fiber, lignin carbon fiber, glassy carbon fiber, activated carbon fiber and the like can be mentioned.

The oxide or chalcogen compound of a metal or semi-metal group used in the non-aqueous electrolyte secondary battery of the present invention is a compound comprising atoms of groups 13, 14, and 15 of the periodic table and oxygen or chalcogen atoms. In the present invention, as the negative electrode material, an amorphous chalcogen compound or an amorphous oxide mainly containing three or more kinds of atoms selected from Group 1, 2, 13, 14, and 15 atoms of the periodic table is particularly preferably used. The term “amorphous” as used herein refers to a substance having a broad scattering band having a peak at 20 ° to 40 ° in 2θ value by X-ray diffraction using CuKα ray, and having a crystalline diffraction line. Is also good. Preferably 40 ° or more and 70 ° in 2θ value
Among the crystalline diffraction lines shown below, the strongest intensity is 2
It is preferably 500 times or less, more preferably 100 times or less, particularly preferably 5 times or less, the diffraction line intensity of the peak of the broad scattering band seen at 20 ° or more and 40 ° or less in θ value, Most preferably, it has no crystalline diffraction lines.

The above chalcogen compound and oxide are B,
Al, Ga, In, Tl, Si, Ge, Sn, Pb,
A complex chalcogen compound and a complex oxide mainly containing two or more elements among P, As, Sb, and Bi are more preferable.
Particularly preferred is a complex chalcogen compound or oxide mainly composed of two or more elements among B, Al, Si, Ge, Sn and P. These complex chalcogen compounds and complex oxides contain at least one element selected from the elements of Groups 1 and 2 of the periodic table in order to mainly modify the amorphous structure.

Among the above-mentioned negative electrode materials, an amorphous composite oxide mainly composed of Sn is preferable, and is represented by the following general formula (3). Formula ⁽³⁾ SnM 3 _c M ⁴ in _d O _t formula, M ³ is Al, B, P, Si, at least one of Ge
M ⁴ represents at least one element of Group 1 and Group 2 of the periodic table, c is a number greater than 0.2 and less than 2, d is a number of 0.01 or more and 1 or less. , 0.2 <c + d <3, t
Represents a number of 1 or more and 6 or less.

As the amorphous composite oxide used in the nonaqueous electrolyte secondary battery of the present invention, any of a firing method and a solution method can be adopted, but the firing method is more preferable. In the baking method, it is preferable to mix well the oxides or compounds of the elements described in the general formula (1) and then bake to obtain an amorphous composite oxide.

As the firing conditions, the heating rate is preferably 5 ° C. to 200 ° C./min, the firing temperature is preferably 500 ° C. to 1500 ° C., and the firing time is Is more than 1 hour 10
It is preferably 0 hours or less. And, it is preferable as the descending rate of temperature or less per minute 2 ℃ least 10 ⁷ ° C.. The rate of temperature rise in the production of the nonaqueous electrolyte secondary battery of the present invention is an average rate of temperature rise from "50% of firing temperature (expressed in ° C)" to "80% of firing temperature (expressed in ° C)". In the present invention, the temperature decreasing rate in the present invention refers to a firing temperature (° C.
80% of the display) to “50% of the firing temperature (° C)”
Is the average rate of temperature drop to reach.

The temperature may be cooled in a firing furnace, or may be taken out of the firing furnace and put into, for example, water to cool. Also ceramic processing (Gihodo Publishing 19
87) Gun method described on page 217, Hammer-Anv
An ultra-quenching method such as an il method, a slap method, a gas atomizing method, a plasma spray method, a centrifugal quenching method, and a melt drag method can also be used. Alternatively, cooling may be performed using a single roller method or a twin roller method described in page 172 of the New Glass Handbook (Maruzen 1991). In the case of a material that melts during firing, a fired product may be continuously taken out while supplying raw materials during firing. In the case of a material that melts during firing, it is preferable to stir the melt.

The firing gas atmosphere is preferably an atmosphere having an oxygen content of 5% by volume or less, and more preferably an inert gas atmosphere. Examples of the inert gas include nitrogen, argon, helium, krypton, xenon, and the like. The most preferred inert gas is pure argon.

The average particle size of the compound used for producing the nonaqueous electrolyte secondary battery of the present invention is preferably 0.1 to 60 μm. More specifically, it is preferable that the average particle size is 0.7 to 25 μm and 60% or more of the total volume is 0.5 to 30 μm. In the nonaqueous electrolyte secondary battery of the present invention, the volume occupied by the particle group having a particle size of 1 μm or less of the negative electrode active material is 30% or less of the total volume, and the volume occupied by the particle group having a particle size of 20 μm or more is the total volume. Is preferably 25% or less. It goes without saying that the particle size of the material used does not exceed the thickness of the mixture on one side of the negative electrode.

To obtain a predetermined particle size, a well-known pulverizer or classifier is used. For example, mortar, ball mill, sand mill, vibration ball mill, satellite ball mill,
A planetary ball mill, a swirling jet mill, a sieve, or the like is used. At the time of pulverization, wet pulverization in the presence of water or an organic solvent such as methanol can also be performed if necessary. Classification is preferably performed to obtain a desired particle size. The classification method is not particularly limited, and a sieve, an air classifier, or the like can be used as necessary. Classification can be performed both in a dry type and a wet type. The average particle size is a median size of primary particles, and is measured by a laser diffraction type particle size distribution measuring device. The specific surface area of the negative electrode material of the nonaqueous electrolyte secondary battery of the present invention is preferably from 0.1 to ⁵ m ² / g as measured by a BET specific surface area measurement method.

Examples of the negative electrode material of the nonaqueous electrolyte secondary battery of the present invention are shown below, but the present invention is not limited to these. SnAl _0.4 B _0.5 P _0.5 K _0.1 O _3.65 , Sn
Al _0.4 B _0.5 P _0.5 Na _0.2 O _3.7 , SnAl _0.4 B
_0.3 P _0.5 Rb _0.2 O _3.4 , SnAl _0.4 B _0.5 P _0.5
Cs _0.1 O _3.65 , SnAl _0.4 B _0.5 P _0.5 K _0.1 Ge
_0.05 O _3.85 , SnAl _0.4 B _0.5 P _0.5 K _0.1 Mg _0.1
Ge _0.02 O _3.83 , SnAl _0.4 B _0.4 P _0.4 O _3.2 , S
nAl _0.3 B _0.5 P _0.2 O _2.7 , SnAl _0.3 B _0.5 P
_0.2 O _2.7 , SnAl _0.4 B _0.5 P _0.3 Ba _0.08 Mg
_0.08 O _3.26 , SnAl _0.4 B _0.4 P _0.4 Ba
_0.08 O _3.28 , SnAl _0.4 B _0.5 P _0.5 O _3.6 , SnA
l _0.4 B _0.5 P _0.5 Mg _0.1 O _3.7 ,

SnAl _0.5 B _0.4 P _0.5 Mg _0.1 F _0.2
O _3.65 , SnB _0.5 P _0.5 Li _0.1 Mg _0.1 F _0.2 O
_{3.05, SnB 0.5 P 0.5 K 0.1} Mg 0.1 F 0.2 O 3.05,
SnB _0.5 P _0.5 K _0.05 Mg _0.05 F _0.1 O _3.03 , SnB
_0.5 P _0.5 K _0.05 Mg _0.1 F _0.2 O _3.03 , SnAl _{0.4
B 0.5 P 0.5 Cs 0.1 Mg 0.1} F 0.2 O 3.65, SnB
_0.5 P _0.5 Cs _0.05 Mg _0.05 F _0.1 O _3.03 , SnB _{0.5
P 0.5 Mg 0.1 F 0.1 O 3.05} , SnB 0.5 P 0.5 Mg
_0.1 F _0.2 O ₃ , SnB _0.5 P _0.5 Mg _0.1 F _0.06 O
_3.07 , SnB _0.5 P _0.5 Mg _0.1 F _0.14 O _3.03 , SnP
Ba _0.08 O _3.58 , SnPK _0.1 O _3.55 , SnPK _0.05 M
g _0.05 O _3.58 , SnPCs _0.1 O _3.55 , SnPBa _0.08
F _0.08 O _3.54 , SnPK _0.1 Mg _0.1 F _0.2 O _3.55 , S
nPK _0.05 Mg _0.05 F _0.1 O _3.53 , SnPCs _0.1 Mg
_0.1 F _0.2 O _3.55 , SnPCs _0.05 Mg _0.05 F _0.1 O
_3.53 ,

Sn _1.1 Al _0.4 B _0.2 P _0.6 Ba _0.08 F
_0.08 O _3.54 , Sn _1.1 Al _0.4 B _0.2 P _0.6 Li _0.1 K
_{0.1 Ba 0.1 F 0.1 O 3.65,} Sn 1.1 Al 0.4 B 0.4 P
_0.4 Ba _0.08 O _3.34 , Sn _1.1 Al _0.4 PCs _0.05 O
_4.23 , Sn _1.1 Al _0.4 PK _0.05 O _4.23 , Sn _1.2 Al
_0.5 B _0.3 P _0.4 Cs _0.2 O _3.5 , Sn _1.2 Al _0.4 B
_0.2 P _0.6 Ba _0.08 O _3.68 , Sn _1.2 Al _0.4 B _0.2 P
_0.6 Ba _0.08 F _0.08 O _3.64 , Sn _1.2 Al _0.4 B _0.2 P
_0.6 Mg _0.04 Ba _0.04 O _3.68 , Sn _1.2 Al _0.4 B _0.3
P _0.5 Ba _0.08 O _3.58 , Sn _1.3 Al _0.3 B _0.3 P _0.4
Na _0.2 O _3.3 , Sn _1.3 Al _0.2 B _0.4 P _0.4 Ca _0.2
O _3.4 , Sn _1.3 Al _0.4 B _0.4 P _0.4 Ba _0.2 O _3.6
, Sn _1.4 Al _0.4 PK _0.2 O _4.6 , Sn _1.4 Al _0.2
Ba _0.1 PK _0.2 O _4.45 , Sn _1.4 Al _0.2 Ba _0.2
PK _0.2 O _4.6 , Sn _1.4 Al _0.4 Ba _0.2 PK _0.2 B
a _0.1 F _0.2 O _4.9 , Sn _1.4 Al _0.4 PK _0.3
O _4.65 , Sn _1.5 Al _0.2 PK _0.2 O _4.4 , Sn _1.5 A
l _0.4 PK _0.1 O _4.65 , Sn _1.5 Al _0.4 PCs _0.05 O
_4.63 , Sn _1.5 Al _0.4 PCs _0.05 Mg _0.1 F _0.2 O
_4.63 ,

SnSi _0.5 Al _0.1 B _0.2 P _0.1 Ca
_0.4 O _3.1 , SnSi _0.4 Al _0.2 B _0.4 O _2.7 , Sn
Si _0.5 Al _0.2 B _0.1 P _0.1 Mg _0.1 O _2.8 , SnS
i _0.6 Al _0.2 B _0.2 O _2.8 , SnSi _0.5 Al _0.3 B
_0.4 P _0.2 O _3.55 , SnSi _0.5 Al _0.3 B _0.4 P _0.5
O _4.30 , SnSi _0.6 Al _0.1 B _0.1 P _0.3 O _3.25 , S
nSi _0.6 Al _0.1 B _0.1 P _0.1 Ba _0.2 O _2.95 , Sn
Si _0.6 Al _0.1 B _0.1 P _0.1 Ca _0.2 O _2.95 , SnS
i _0.6 Al _0.4 B _0.2 Mg _0.1 O _3.2 , SnSi _0.6 A
l _0.1 B _0.3 P _0.1 O _3.05 , SnSi _0.6 Al _0.2 Mg
_0.2 O _2.7 , SnSi _0.6 Al _0.2 Ca _0.2 O _2.7 , S
nSi _0.6 Al _0.2 P _0.2 O ₃ , SnSi _0.6 B _0.2 P
_0.2 O ₃ , SnSi _0.8 Al _0.2 O _2.9 , SnSi _0.8
Al _0.3 B _0.2 P _0.2 O _3.85 , SnSi _0.8 B _0.2 O
_2.9 , SnSi _0.8 Ba _0.2 O _2.8 , SnSi _0.8 Mg
_0.2 O _2.8 , SnSi _0.8 Ca _0.2 O _2.8 , SnSi
_0.8 P _0.2 O _3.1 ,

Sn _0.9 Mn _0.3 B _0.4 P _0.4 Ca _0.1 R
b _0.1 O _2.95 , Sn _0.9 Fe _0.3 B _0.4 P _0.4 Ca _0.1
Rb _0.1 O _2.95 , Sn _0.8 Pb _0.2 Ca _0.1 P _0.9 O
_3.35 , Sn _0.3 Ge _0.7 Ba _0.1 P _0.9 O _3.35 , Sn
_0.9 Mn _0.1 Mg _0.1 P _0.9 O _3.35 , Sn _0.2 Mn _0.8
Mg _0.1 P _0.9 O _3.35 , Sn _0.7 Pb _0.3 Ca _0.1 P
_0.9 O _3.35 , Sn _0.2 Ge _0.8 Ba _0.1 P _0.9 O _3.35 ,

SnSi _0.8 B _0.2 O _2.9 , SnSi _0.7
B _0.3 O _2.85 , SnSi _0.7 B _0.3 Al _0.1 O _3.0 , S
nSi _0.5 B _0.3 Al _0.1 Mg _0.1 O _2.7 , Sn _0.8 S
i _0.6 B _0.2 Al _0.1 Li _0.1 O _2.5 , Sn _0.8 Si _0.6
B _0.2 Al _0.1 Cs _0.1 O _2.65 , Sn _0.8 Si _0.7 B
_0.1 P _0.1 Al _0.1 O _2.75 , Sn _0.8 Si _0.5 B _0.3 P
_0.2 Al _0.1 O _2.9 , Sn _0.8 Si _0.7 B _0.1 P _0.1 A
l _0.1 Li _0.05 O _2.78 , Sn _0.8 Si _0.5 B _0.3 P _0.1
Al _0.1 Li _0.1 O _2.7 , Sn _0.8 Si _0.5 B _0.3 P
_0.2 Al _0.1 Cs _0.1 O _2.95 , Sn _0.8 Si _0.7 P _0.3
O _2.95 , Sn _0.8 Si _0.7 P _0.3 Al _0.1 O _3.1 , Sn
Si _0.5 B _0.3 Zr _0.1 O _2.65 , Sn _0.8 Si _0.6 P
_0.2 Zr _0.1 O _2.7 , Sn _0.8 Si _0.6 B _0.2 P _0.1 Z
r _0.1 O _2.75

The chemical formula of the compound obtained by calcination can be calculated by inductively coupled plasma (ICP) emission spectroscopy as a measuring method, and from the weight difference of powder before and after calcination as a simple method.

The negative electrode material of the non-aqueous electrolyte secondary battery of the present invention can be used by inserting a light metal, particularly lithium. Methods for inserting lithium include an electrochemical method, a chemical method, and a thermal method. Particularly preferred is an electrochemical method, for example, by attaching a small piece of metal mainly composed of lithium on the uncoated portion of the negative electrode mixture of the current collector or on the negative electrode mixture layer, and inserting it by contacting with the electrolytic solution. it can. In particular, a method of electrochemically inserting lithium in a battery is preferable. Small pieces of metal mainly composed of lithium have a thickness of 5-2.
It is preferable to stick a foil of 00 μm in small pieces such as strips.

The lithium can be inserted up to 0.01 V when lithium is used as a counter electrode, and more preferably up to 0.05 V. A particularly preferred method is
This is a method in which lithium is partially inserted in order to compensate for the irreversible capacity of the negative electrode material, and a method in which lithium is inserted up to 0.3 V when lithium is used as a counter electrode. A more specific lithium insertion amount is 0.04 g / g of the negative electrode material.
05 g to 0.5 g, more preferably 0.03 g to 0.2
g, particularly preferably 0.06 g to 0.15 g. When the negative electrode material is a metal oxide, the equivalent amount per mole of the metal oxide is 0.5 to 4.0 equivalents, more preferably 1 to 3.5 equivalents, and particularly preferably 1.2 to 3 equivalents. .2
Is equivalent. When less than 1.2 equivalents of lithium were preliminarily inserted into the negative electrode material, the battery capacity was low, and 3.2
If more lithium than the equivalent is preliminarily inserted, the cyclability deteriorates, which is not preferable.

The amount of lithium inserted can be arbitrarily controlled by the amount of lithium superimposed on the negative electrode sheet. As the metal mainly composed of lithium, it is preferable to use lithium metal, but the purity is preferably 90% by weight or more, and particularly preferably 98% by weight or more. It is preferable that the lithium superimposed pattern on the negative electrode sheet is superimposed on the entire surface of the sheet. Also, any of the disk-shaped partial overlaps is preferable. The term “overlap” as used herein means that a metal foil mainly composed of lithium is pressure-bonded directly onto a sheet having a negative electrode mixture and an auxiliary layer.

The covering rate of the metal foils on the negative electrode sheet is preferably from 10 to 100%, more preferably from 15 to 100%, particularly preferably from 20 to 100%. If it is less than 20%, the preliminary insertion of lithium may be non-uniform, which is not preferable. Further, from the viewpoint of uniformity, the thickness of the metal foil mainly composed of lithium is preferably 5 to 150 μm, more preferably 5 to 100 μm,
75 μm is particularly preferred. The handling atmosphere such as cutting and pasting of metal foil mainly composed of lithium has a dew point of -30.
It is preferable to be in a dry air or argon gas atmosphere at a temperature of not higher than -80 ° C or higher. In the case of dry air, the temperature is more preferably -40 ° C or lower and -80 ° C or higher. In handling, carbon dioxide may be used in combination. Particularly, in the case of an argon gas atmosphere, it is preferable to use a carbon dioxide gas in combination.

The conductive agent used for the mixture of the non-aqueous electrolyte secondary battery of the present invention may be any conductive material which does not cause a chemical change in the formed battery. Specific examples include flake graphite, flake graphite, natural graphite such as earthy graphite, petroleum coke, coal coke, celluloses, sugars, high-temperature fired bodies such as mesophase pitch, and graphite such as artificial graphite such as vapor-grown graphite. , Carbon blacks such as acetylene black, furnace black, ketjen black, channel black, lamp black, and thermal black, asphalt pitch, coal tar, activated carbon, meso fuse pitch, carbon materials such as polyacene, and conductive materials such as metal fibers. Examples thereof include fibers, metal powders such as copper, nickel, aluminum and silver, conductive whiskers such as zinc oxide and potassium titanate, and conductive metal oxides such as titanium oxide. In the case of graphite, it is preferable to use a plate-like graphite having an aspect ratio of 5 or more. Among these, graphite and carbon black are preferred,
The size of the particles is preferably 0.01 μm or more and 20 μm or less, more preferably 0.02 μm or more and 10 μm or less. These may be used alone or in combination of two or more. When used together, it is preferable to use carbon blacks such as acetylene black and graphite particles of 1 to 15 μm in combination. The amount of the conductive agent added to the mixture layer is preferably 1 to 50% by weight, and more preferably 2 to 30% by weight, based on the negative electrode material or the positive electrode material. For carbon black and graphite, the content is particularly preferably 3 to 20% by weight.

In the non-aqueous electrolyte secondary battery of the present invention, a binder is used to hold the electrode mixture. Examples of the binder include polysaccharides, thermoplastic resins, and polymers having rubber elasticity. Preferred binders include starch, carboxymethylcellulose, cellulose, diacetylcellulose, methylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, sodium alginate, polyacrylic acid, sodium polyacrylate, polyvinylphenol, polyvinylmethylether, polyvinyl alcohol, polyvinylpyrrolidone , Polyacrylamide, polyhydroxy (meth) acrylate, water-soluble polymers such as styrene-maleic acid copolymer, polyvinyl chloride, polytetrafluoroethylene, polyvinylidene fluoride, tetrafluoroethylene-hexafluoropropylene copolymer, vinylidene fluoride -Tetrafluoroethylene-hexafluoropropylene copolymer, polyethylene, polypropylene, ethylene Propylene -
Dienterpolymer (EPDM), sulfonated EPD
M, polyvinyl acetal resin, (meth) acrylate copolymer containing (meth) acrylate such as methyl methacrylate, 2-ethylhexyl acrylate, etc., (meth) acrylate-acrylonitrile copolymer, vinyl acetate, etc. Polyvinyl ester copolymer containing vinyl ester, styrene-butadiene copolymer, acrylonitrile-butadiene copolymer, polybutadiene, neoprene rubber, fluoro rubber, polyethylene oxide, polyester polyurethane resin,
Emulsions (latex) or suspensions of a polyether polyurethane resin, a polycarbonate polyurethane resin, a polyester resin, a phenol resin, an epoxy resin and the like can be given. In particular, polyacrylate latex, carboxymethylcellulose, polytetrafluoroethylene, and polyvinylidene fluoride are exemplified. As these binders, it is preferable to use those obtained by dispersing fine powder in water, and it is more preferable to use those in which the average size of the particles in the dispersion is 0.01 to 5 μm, and 0.05 to 1 μm. It is particularly preferred to use one.

These binders can be used alone or as a mixture. If the amount of the binder is small, the holding power and cohesive strength of the electrode mixture are weak. If it is too large, the electrode volume increases and the capacity per unit volume or unit weight of the electrode decreases.
For these reasons, the amount of the binder added is preferably 1 to 30% by weight, particularly preferably 2 to 10% by weight.

As the filler, any fibrous material that does not cause a chemical change in the constructed battery can be used. Usually, fibers such as olefin-based polymers such as polypropylene and polyethylene, glass, and carbon are used. Although the amount of the filler is not particularly limited,
30% by weight is preferred. As the ionic conductive agent, those known as inorganic and organic solid electrolytes can be used, and the details are described in the section of the electrolytic solution. The pressure booster is a compound for raising the internal pressure of the battery, and a carbonate such as lithium carbonate is a typical example.

In the current collector which can be used in the nonaqueous electrolyte secondary battery of the present invention, the positive electrode is aluminum, stainless steel, nickel, titanium, or an alloy thereof, and the negative electrode is copper, stainless steel, nickel, titanium, or these. Alloy. The form of the current collector is foil, expanded metal, punched metal, or wire mesh. In particular, an aluminum foil is preferable for the positive electrode, and a copper foil is preferable for the negative electrode.

Next, the structure of the positive and negative electrodes in the non-aqueous electrolyte secondary battery of the present invention will be described. The positive and negative electrodes preferably have a form in which an electrode mixture is applied to both surfaces of a current collector.
In this case, the number of layers per side may be one or two or more. When the number of layers per side is two or more, the number of layers containing the positive electrode active material (or the negative electrode material) may be two or more. A more preferable configuration is a case where the layer includes a layer containing a positive electrode active material (or a negative electrode material) and a layer containing no positive electrode active material (or a negative electrode material). The layer containing no positive electrode active material (or negative electrode material) includes a protective layer for protecting the layer containing the positive electrode active material (or negative electrode material), and a layer between the divided positive electrode active material (or negative electrode material) containing layer. And an undercoat layer between the positive electrode active material (or negative electrode material) -containing layer and the current collector. These are collectively referred to as an auxiliary layer in the present invention.

The protective layer is preferably on both the positive and negative electrodes or on either the positive or negative electrode. In the negative electrode, when lithium is inserted into the negative electrode material in the battery, the negative electrode preferably has a form having a protective layer. The protective layer is composed of at least one layer, and may be composed of a plurality of layers of the same type or different types. Further, the current collector may have a form in which the protective layer is provided only on one side of the mixture layer on both sides. These protective layers are composed of water-insoluble particles, a binder and the like. As the binder, the binder used when forming the above-mentioned electrode mixture can be used. As the water-insoluble particles, various kinds of conductive particles, organic and inorganic particles having substantially no conductivity can be used. The solubility of the water-insoluble particles in water is preferably 100 ppm or less, and more preferably insoluble. The proportion of the particles contained in the protective layer is preferably 2.5% by weight or more and 96% by weight or less, more preferably 5% by weight or more and 9% by weight or less.
The content is more preferably 5% by weight or less, particularly preferably 10% by weight or more and 93% by weight or less.

Examples of the water-insoluble conductive particles include metals, metal oxides, metal fibers, carbon fibers, and carbon particles such as carbon black and graphite. Among these water-insoluble conductive particles, those having low reactivity with alkali metals, particularly lithium, are preferable, and metal powder and carbon particles are more preferable. The electric resistivity at 20 ° C. of the elements constituting the particles is preferably 5 × 10 ⁹ Ω · m or less.

As the metal powder, a metal having low reactivity with lithium, that is, a metal which is unlikely to form a lithium alloy is preferable, and specifically, copper, nickel, iron, chromium, molybdenum, titanium, tungsten, and tantalum are preferable. The shape of these metal powders may be any of a needle shape, a column shape, a plate shape, and a lump shape, and the maximum diameter is preferably 0.02 μm or more and 20 μm or less, more preferably 0.1 μm or more and 10 μm or less. It is preferable that the surface of these metal powders is not excessively oxidized. When the surfaces are oxidized, it is preferable to perform heat treatment in a reducing atmosphere.

As the carbon particles, known carbon materials which are conventionally used as a conductive material to be used together when the electrode active material is not conductive can be used. Specifically, a conductive agent used when preparing an electrode mixture is used.

Examples of the water-insoluble particles having substantially no conductivity include fine powder of Teflon, SiC, aluminum nitride, alumina, zirconia, magnesia, mullite, forsterite, and steatite.
These particles may be used in combination with the conductive particles, and are preferably used in an amount of 0.01 to 10 times the conductive particles.

The positive (negative) electrode sheet can be prepared by applying a positive (negative) electrode mixture on a current collector, drying and compressing. For the preparation of the mixture, a positive electrode active material (or a negative electrode material) and a conductive agent are mixed, a binder (a suspension or emulsion of resin powder), and a dispersion medium are added and kneaded and mixed. The dispersion can be carried out by a mixer, a homogenizer, a dissolver, a planetary mixer, a paint shaker, a sand mill or other agitating mixer or disperser. Water or an organic solvent is used as the dispersion medium, but water is preferred. In addition, additives such as a filler, an ion conductive agent, and a pressure enhancer may be appropriately added. The pH of the dispersion is 5 to 10 for the negative electrode and 7 to 10 for the positive electrode.
12 is preferred.

The coating can be performed by various methods.
Examples of the method include a reverse roll method, a direct roll method, a blade method, a knife method, an extrusion method, a slide method, a curtain method, a gravure method, a bar method, a dip method, and a squeeze method. A method using an extrusion die and a method using a slide coater are particularly preferable. The coating is preferably performed at a speed of 0.1 to 100 m / min. At this time, by selecting the above-mentioned coating method in accordance with the liquid physical properties and drying properties of the mixture paste, a good surface state of the coating layer can be obtained.
When the electrode layer has a plurality of layers, it is preferable to apply the plurality of layers simultaneously from the viewpoint of uniform electrode production, production cost, and the like. The thickness, length and width of the coating layer are determined by the size of the battery. A typical thickness of the coating layer is 10 to 1000 μm in a compressed state after drying. The electrode sheet after application is hot air, vacuum, infrared, far infrared,
It is dried and dehydrated by the action of electron beams and low humidity air. These methods can be used alone or in combination. The drying temperature is preferably in the range of 80 to 350C, particularly preferably in the range of 100 to 260C. The water content after drying is preferably 200 ppm or less, more preferably 100 ppm or less. For the compression of the electrode sheet, a commonly used pressing method can be used, but a die pressing method and a calendar pressing method are particularly preferable. The press pressure is not particularly limited, but is preferably 10 kg / cm ^{2 to 3} t / cm ² . The press speed of the calendar press method is 0.1 to 5
0 m / min is preferred. The pressing temperature is preferably from room temperature to 200 ° C.

The separator which can be used in the non-aqueous electrolyte secondary battery of the present invention is not limited as long as it has a high ion permeability, a predetermined mechanical strength, and an insulating thin film. Polymers, cellulosic polymers, polyimides, nylons, glass fibers, and alumina fibers are used, and nonwoven fabrics, woven fabrics, and microporous films are used as forms. In particular, the material is preferably polypropylene, polyethylene, a mixture of polypropylene and polyethylene, a mixture of polypropylene and Teflon, a mixture of polyethylene and Teflon, and the form is preferably a microporous film. In particular, when the pore size is 0.01
A microporous film having a thickness of 1 to 1 µm and a thickness of 5 to 50 µm is preferred. Even if these microporous films are single membranes,
A composite film composed of two or more layers having different properties such as the shape, density, and material of the micropores may be used. For example, a composite film obtained by laminating a polyethylene film and a polypropylene film can be used.

The battery can and the battery cover which can be used in the non-aqueous electrolyte secondary battery of the present invention are made of nickel-plated iron steel plate, stainless steel plate (SUS304, SUS30).
4L, SUS304N, SUS316, SUS316
L, SUS430, SUS444, etc.), a nickel-plated stainless steel plate (same as above), aluminum or its alloy, nickel, titanium, and copper.
They are a true circular cylinder, an elliptical cylinder, a square cylinder, and a rectangular cylinder. In particular, when the outer can also serves as the negative electrode terminal, a stainless steel plate or a nickel-plated iron steel plate is preferable, and when the outer can also serves as the positive electrode terminal, a stainless steel plate, aluminum or an alloy thereof is preferable. The shape of the battery can may be any of buttons, coins, sheets, cylinders, corners, and the like. A safety valve can be used for the sealing plate as a measure against the rise in the internal pressure of the battery can. In addition, a method of cutting a member such as a battery can or a gasket can be used. In addition, various conventionally known safety elements (for example, fuses, bimetals,
PTC element).

For the lead plate used in the non-aqueous electrolyte secondary battery of the present invention, a metal having electrical conductivity (for example, iron, nickel, titanium, chromium, molybdenum, copper, aluminum, etc.) or an alloy thereof is used. be able to. Known methods (eg, DC or AC electric welding, laser welding, ultrasonic welding) can be used for welding the battery lid, battery can, electrode sheet, and lead plate. A conventionally known compound or mixture such as asphalt can be used as the sealing agent for closing.

The gasket that can be used in the non-aqueous electrolyte secondary battery of the present invention is made of a material such as olefin polymer, fluorine polymer, cellulose polymer, polyimide,
It is a polyamide, and from the viewpoint of resistance to organic solvents and low moisture permeability, an olefin-based polymer is preferable, and a polymer mainly composed of propylene is particularly preferable. Further, it is preferably a block copolymer of propylene and ethylene.

The battery assembled as described above is
It is preferable to perform an aging treatment. The aging treatment includes a pretreatment, an activation treatment, and a post-treatment, whereby a battery having high charge / discharge capacity and excellent cycleability can be manufactured. The pre-treatment is a treatment for making the distribution of lithium in the electrode uniform, such as a control of dissolution of lithium, a temperature control for making the distribution of lithium uniform, a swing and / or rotation treatment, and an optional charge and discharge. Are performed. The activation process is a process for inserting lithium into the negative electrode of the battery body, and it is preferable to insert 50 to 120% of the amount of lithium inserted when the battery is actually used and charged.
The post-processing is a process for sufficiently activating the activation process,
There are a preservation process for making the battery reaction uniform and a charge / discharge process for determination, and these can be arbitrarily combined.

[0066] The battery of the present invention is covered with an exterior material as necessary. Examples of the exterior material include a heat-shrinkable tube, an adhesive tape, a metal film, paper, cloth, paint, a plastic case, and the like. Further, at least a part of the exterior may be provided with a portion that changes color by heat so that the heat history during use can be recognized.

The batteries of the present invention are assembled in series and / or in parallel as required, and stored in a battery pack. In addition to safety elements such as positive temperature coefficient resistors, thermal fuses, fuses and / or current interrupting elements, battery packs have safety circuits (voltage, temperature, current, etc. of each battery and / or assembled battery as a whole, Then, a circuit having a function of interrupting the current may be provided. In addition to the positive and negative terminals of the whole battery pack, the positive and negative terminals of each battery, the temperature detection terminals of the whole battery pack and each battery, the current detection terminals of the whole battery pack, etc. shall be provided as external terminals on the battery pack. Can also. The battery pack may have a built-in voltage conversion circuit (such as a DC-DC converter). In addition, connection of each battery
The lead plate may be fixed by welding, or may be fixed with a socket or the like so as to be easily detachable. Further, the battery pack may be provided with a display function of the remaining battery capacity, the presence or absence of charging, the number of times of use, and the like.

The battery of the present invention is used for various devices.
In particular, video movies, portable VCRs with built-in monitors, movie cameras with built-in monitors, digital cameras, compact cameras, SLR cameras, film with lenses, notebook computers, notebook word processors, electronic organizers,
It is preferably used for mobile phones, cordless phones, razors, electric tools, electric mixers, automobiles and the like.

[0069]

The present invention will be described in more detail with reference to specific examples, but the present invention is not limited to the examples unless it exceeds the gist of the invention.

Example 1 As the test battery, the battery No. 6 of Example 3 of JP-A-7-313219 was used. This battery was made as follows. The preparation of the mixture was as follows. As a negative electrode material, SnSiO ₃ (SnO, SiO ₂
, Baked at 1000 ° C. for 12 hours, and then synthesized and pulverized by a jet mill), and 80% by weight of flake graphite and acetylene black were mixed in a ratio of 9: 5 as a conductive agent. Then, 4% by weight of an aqueous dispersion of styrene-butadiene rubber and 1% by weight of carboxymethylcellulose were added as binders and kneaded with water as a medium to prepare a slurry. The slurry is 18 μm thick.
On both sides of the copper foil by extrusion method,
After drying, it was compression-molded by a calender press and cut into a predetermined width and length to produce a strip-shaped negative electrode sheet. The positive electrode material contained 87% by weight of LiCoO ₂ (a commercially available product) as a positive electrode active material, 6% by weight of flaky graphite, 3% by weight of acetylene black, and 3% by weight of a polytetrafluoroethylene aqueous dispersion as a binder. A slurry obtained by adding 1% by weight of sodium polyacrylate and kneading with water as a medium was applied to both surfaces of an aluminum foil having a thickness of 20 μm in the same manner as described above, dried, pressed, and cut to produce a belt-shaped positive electrode sheet. . After nickel and aluminum lead plates were spot-welded to the ends of the negative electrode sheet and the positive electrode sheet, dehydration and drying were performed at 210 ° C. for 2 hours in dry air having a dew point of −40 ° C. or less. Further, a positive electrode sheet (water content: 15 ppm) after dehydration and drying, a microporous polypropylene film separator (Celgard 2400), a negative electrode sheet (water content: 20 ppm) after dehydration and drying, and a separator are laminated in this order, and these are spirally wound by a winding machine. Wound.

The wound body was housed in a nickel-plated iron bottomed cylindrical battery can also serving as a negative electrode terminal. Further, 1 mol / l LiPF ₆ (a mixture of ethylene carbonate and diethyl carbonate in a volume ratio of 2: 8, hydrogen fluoride content of 8 ppm) was injected into the battery can as an electrolyte. After a sealing agent mainly composed of asphalt is applied to the battery can side of a polypropylene gasket (not annealed), a battery lid having a positive electrode terminal is caulked through this gasket to produce a cylindrical battery (A-1). did. In addition,
The positive electrode terminal was connected to the positive electrode sheet and the battery can was connected to the negative electrode sheet by a lead terminal in advance. Battery (A-2) was prepared in exactly the same manner as battery (A-1) except that a gasket made of polypropylene, which had been annealed at 105 ° C. for 1 hour in advance, was used. Ten batteries were prepared for each. The battery was manufactured by inserting the electrode into the battery can, injecting the electrolyte, and sealing the battery can at a dew point of −50 ° C. or less.

These batteries were subjected to a charge / discharge test of 250 cycles at a current density of 1 mA / cm ² (4.1 V to 2.7 V).
Was done. In the 300th discharge capacity, the average value of each battery was 310 mAh / g and 315 mAh / g. When three of each of these batteries were disassembled and the amount of free hydrogen fluoride was quantified, both batteries A-1 and A-2 were 50 to 60.
ppm.

The remaining battery was further charged to 3.2 V
After discharging the battery, it was stored in a room at about 25 ° C. and 60% humidity for 3 years. When these five batteries were disassembled and the amount of free hydrogen fluoride was quantified, the battery (A-2) showed 150 to 26
0 ppm, and the battery (A-1) had a concentration of 330 to 780 ppm. The remainder of battery (A-1) was subjected to a charge / discharge test.
While charging / discharging was not possible, battery (A-2) was chargeable / dischargeable. From the above, the effect of the battery (A-2) of the present invention using the annealed gasket is clear.
The amount of free hydrogen fluoride of the battery (A-3) using a gasket coated with a sealing agent was 100 to 1
The battery (A-4) using a gasket which is 50 ppm and smaller than that of the battery (A-2), and in which the sealing agent is applied and dried, and the sealing agent is applied again, has a quantitative value of the amount of free hydrogen fluoride of 90 to 110 ppm. It was low and had the smallest range of measurements.

Example 2 The relationship between the amount of hydrogen fluoride detected from the electrolyte and the battery performance will be described. [Preparation of positive electrode mixture paste] Positive electrode active material: LiCoO ₂ (a mixture of lithium carbonate and tricobalt tetroxide mixed at a molar ratio of 3: 2 was placed in an alumina crucible and heated to 750 ° C. at 2 ° C./min in air. After heating and calcining for 4 hours, the temperature was further raised to 900 ° C. at a rate of 2 ° C. per minute, and calcined at that temperature for 8 hours to be crushed, and 50 g of powder having a center particle size of 5 μm was dispersed in 100 ml of water. The conductivity of the dispersion at this time is 0.6 mS / m, the pH is 10.1, and the specific surface area by the nitrogen adsorption method is 0.42 m ² / g).
And 10 g of acetylene black with a homogenizer, followed by 8 g of an aqueous dispersion of a copolymer of 2-ethylhexyl acrylate, acrylic acid and acrylonitrile (solids concentration 50% by weight) as a binder, and 2% by weight. Was added and kneaded and mixed, and 50 g of water was further added, followed by stirring and mixing with a homogenizer to prepare a positive electrode mixture paste.

[Preparation of Negative Electrode Mixture Paste] Negative electrode active material: SnSi _0.5 B _0.3 P _0.2 Cs _0.05 Al
_0.1 O _3.13 (11.0 g of tin monoxide, 4.2 mol of tin pyrophosphate)
g, diboron trioxide 1.1 g, cesium carbonate 0.83 g,
3.1 g of silicon dioxide is dry-mixed, put in an alumina crucible, heated to 1000 ° C. at 15 ° C./min in an argon atmosphere, baked at 1100 ° C. for 12 hours, and then cooled to room temperature at 10 ° C./min. What was taken out of the firing furnace was collected and pulverized with a jet mill, average particle size 4.5 μm, Cu
A substance having a broad peak having an apex in the vicinity of 28 ° in 2θ value in an X-ray diffraction method using Kα ray;
No crystalline diffraction line was observed at a θ value of 40 ° or more and 70 ° or less. ) 200 g, conductive agent (artificial graphite) 30 g
And a homogenizer, and further, as a binder, a concentration of 2
A negative electrode mixture paste was prepared by adding and mixing 50 g of a 50% by weight aqueous solution of carboxymethylcellulose and 10 g of polyvinylidene fluoride and 30 g of water, followed by kneading and mixing.

[Preparation of Negative Electrode Protective Layer Paste] Alumina 8
5 g and 9 g of artificial graphite were added to 300 g of a 2% by weight aqueous solution of carboxymethylcellulose, kneaded and mixed to prepare.

[Preparation of Positive and Negative Electrode Sheets] The positive electrode mixture paste prepared above was coated on both surfaces of a 20 μm-thick aluminum foil current collector with a blade coater in an amount of 280 g / m in terms of positive electrode active material per one side. After coating in ² and drying, it was compression molded by a roller press machine so that the thickness of the sheet after compression was 280 μm. Thereafter, the resultant was cut into a predetermined size to form a belt-shaped positive electrode sheet. Further, it was heated with a far-infrared heater in a dry box (dew point: dry air having a temperature of -50 ° C or less), and was sufficiently dehydrated and dried at an electrode temperature of about 250 ° C to prepare a positive electrode sheet (water content: 13 ppm). Similarly, a negative electrode mixture paste and a negative electrode protective layer paste were applied to both surfaces of an 18 μm copper foil current collector. At this time,
The negative electrode mixture paste was applied to the current collector side such that the negative electrode protective layer paste was the uppermost layer. The coating amount of the negative electrode material per one side was 90 g / m ² , and the coating amount of the protective layer was 15 g / m ² .
At m ² , a negative electrode sheet (water content: 20 ppm) having a thickness of 90 μm after compression by a roller press was prepared. A 6 mm wide strip of lithium metal (purity 99.8%) was attached at a pitch of 10 mm to both surfaces of the negative electrode sheet so that the lithium amount was 10 g / m ² . The coverage of lithium on the mixture was 60%.

[Preparation of Electrolyte Solution]
65.3 g of diethyl carbonate was placed in a cc narrow-neck polypropylene container, and 22.2 g of ethylene carbonate was dissolved little by little while taking care that the liquid temperature did not exceed 30 ° C. Next, 0.4 g of LiBF ₄ , 12.1 g of LiBF
While paying attention to PF _{6 so} that the liquid temperature does not exceed 30 ° C,
A small amount was dissolved in each of the polypropylene containers in order. The obtained electrolyte was a colorless and transparent liquid having a specific gravity of 1.135. In the adjustment, the water content was removed as much as possible, and the water content was 5 ppm (measured by a Karen Fischer moisture measurement device (trade name: MKC-210, manufactured by Kyoto Denshi)), and the free acid content was 8 ppm.
(Using bromthymol blue as an indicator, 0.1N Na
(Measured by neutralization titration using an aqueous OH solution) to obtain a reference electrolyte solution. Nitrogen gas having humidity was blown into the reference electrolyte to prepare various electrolytes a to h having different moisture contents.

[Preparation of Cylinder Battery] A cylinder battery as shown in FIG. 1 was prepared. A positive electrode sheet (3), a microporous polyethylene film separator (EF4500, manufactured by Ube Industries) (4), a negative electrode sheet (2), and a separator (4) were laminated in this order, and this was spirally wound. The wound body was housed in a nickel-plated iron bottomed cylindrical battery can (1) also serving as a negative electrode terminal, and then the above-mentioned electrolytic solution was poured into the battery can. After a sealing agent mainly composed of asphalt was applied to a polypropylene gasket (7), a battery lid (13) having a positive electrode terminal was caulked through the gasket (7) to produce a cylindrical battery. The positive electrode terminal was connected to the positive electrode sheet, and the battery can was connected to the negative electrode sheet by a lead terminal in advance. (5) in the figure
Is a lower insulating plate, (6) is an upper insulating plate, (8) is a positive electrode lead, (9) is an explosion-proof valve body, (10) is a current cutoff switch (10a first conductor, 10b second conductor, 10c insulation). (11) is a PTC ring, (13) is a battery cover (also serving as a positive electrode terminal), (15) is a welding plate,
(16) indicates an insulating cover.

After leaving the above battery at room temperature for 12 hours,
Pre-charging was performed for 1 hour under a constant current of 0.1 A, and then aging was performed at 50 ° C. for 10 days. Next, for activation, the battery was charged to 4.2 V at ² mA / cm ² at room temperature. Further, the battery was aged at 55 ° C. for 3 days in a charged state. This battery was charged at a charge end voltage of 4.2.
V (open circuit voltage), discharge end voltage 2.8 V, 2 mA / c
The battery was charged and discharged at a current density of m ² and the initial discharge capacity was measured. The cycle was further repeated, and after the completion of 100 cycles, the discharge capacity was measured, and the retention rate with respect to the initial discharge capacity was obtained. After the measurement, the battery was disassembled and the amount of free hydrogen fluoride was determined. The results are shown in the table below. Table-1 Experimental results Electrolyte Battery discharge capacity retention rate Free hydrogen fluoride amount a 95% 24 ppm b 9548 c 95 90 d 94 140 e 92 190 f 90 280 g 85 360 h 79 500 It can be seen that a battery in which the amount of free hydrogen fluoride detected from the electrolytic solution exceeds 300 ppm has a remarkably low discharge capacity retention rate, and preferably needs to be controlled to 200 ppm or less, particularly preferably 150 ppm or less.

[0081]

The nonaqueous electrolyte secondary battery of the present invention has the advantages of high capacity, excellent storage stability, and long life.

[Brief description of the drawings]

FIG. 1 is a sectional view of a cylinder type battery used in Examples.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Battery can (also serves as negative electrode terminal) 2 Negative electrode sheet 3 Positive electrode sheet 4 Separator 5 Lower insulating plate 6 Upper insulating plate 7 Gasket 8 Positive electrode lead 9 Explosion-proof valve body 10 Current cutoff switch 11 PTC ring 13 Battery cover (also serves as positive electrode terminal) 15 Weld plate 16 Insulation cover

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takuji Yamada 1-6-1, Matsuzakadaira, Yamato-cho, Kurokawa-gun, Miyagi Prefecture Inside Fujifilm Cell-Tech Co., Ltd. (72) Inventor Hiroshi Ishizuka 1-6-1, Matsuzakaira, Yamato-cho, Kurokawa-gun, Miyagi Fuji Film Cell Tech Co., Ltd.

Claims (7)

[Claims] 1. A sealed non-aqueous electrolyte secondary battery comprising a lithium salt-containing non-aqueous electrolyte, which is filled and sealed, and the amount of free acid contained in the non-aqueous electrolyte three years after the sealing. Is a quantity not exceeding 300 ppm. 2. The non-aqueous electrolyte secondary battery according to claim 1, wherein the lithium salt contained in the non-aqueous electrolyte is a lithium salt containing fluorine. 3. The non-aqueous electrolyte secondary battery according to claim 1, wherein the free acid contained in the non-aqueous electrolyte is hydrogen fluoride. 4. A gasket used for a sealing portion, which has been heat-treated after molding.
4. The non-aqueous electrolyte secondary battery according to 2 or 3. 5. The non-aqueous electrolyte secondary according to claim 1, wherein the amount of the free acid contained in the non-aqueous electrolyte before being injected into the battery can is 100 ppm or less. battery. 6. The non-aqueous electrolyte secondary battery according to claim 1, wherein an amount of water contained in the electrode group before being inserted into the battery can is 300 ppm or less. 7. The assembly according to claim 1, wherein an environment at the time of inserting the battery can into the electrode group, injecting the electrolytic solution, and closing the battery can is controlled to a dew point of −50 ° C. or less. The non-aqueous electrolyte secondary battery according to item 6.