JPH10270088A - Non-aqueous electrolyte secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery which provides high voltage and high energy density and has good charging/discharging characteristics, by composing the negative electrode of oxide of silicon which contains lithium, electron conductive powdery carbon, and resin binding agent, using oxide of transition metals as positive electrode active material, and using glass fiber as a separator. SOLUTION: The battery is composed of a negative electrode which consists of oxide of silicon or silicate which contains lithium as active material, electron conductive powdery carbon, and resin binding agent, a positive electrode whose active material is metallic oxide which contains transition metals as its element, and a separator which uses glass fiber material. As low grade oxide which contains lithium, LixSiOy (where, x >=0.2>y>0) is used. The compound is produced by storing lithium ions into SiOy with electrochemical reaction between SiOy (where, 2>y>0) and lithium or lithium-containing material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-aqueous electrolyte secondary battery using a lithium ion conductive non-aqueous electrolyte as a material capable of inserting and extracting lithium as an active material for a negative electrode and a positive electrode. The present invention relates to a secondary battery having a high voltage, a high energy density, excellent charge / discharge characteristics, a long cycle life, high reliability, and a novel battery configuration.

[0002]

2. Description of the Related Art Nonaqueous electrolyte batteries using lithium as a negative electrode active material have advantages such as high voltage, high energy density, low self-discharge, and excellent long-term reliability. It is already widely used as a power source for applications. However, with the recent remarkable development of portable electronic devices and communication devices,
With the emergence of a wide variety of devices that require a large current output from batteries as power sources, there is a strong demand for rechargeable and high-density secondary batteries that can be recharged and discharged from the viewpoint of economy and reduction in size and weight of the devices. ing. For this reason, research and development to promote the non-aqueous electrolyte battery having a high energy density into a secondary battery has been actively carried out, and some of them have been put to practical use. However, energy density, charge / discharge cycle life, reliability, etc. are still insufficient. It is enough.

Conventionally, as a positive electrode active material constituting a positive electrode of this type of secondary battery, the following three types are used depending on the form of charge / discharge reaction.
Species types have been found. The first type is a metal chalcogenide such as TiS ₂ , MoS ₂ , NbSe ₃ , MnO ₂ , MoO ₃ , V ₂ O ₅ , Li _x CoO ₂ , L
_{i X NiO 2, Li x Mn} 2 O 4 or the like as a so metal oxides, only crystals of the interlayer and the grating position or the interstitial gap lithium-ion (cation) of intercalation and deintercalation reactions and the like Type that comes in and out. Second
The type is a type in which mainly anions alone are stably introduced and removed by doping and undoping reactions, such as conductive polymers such as polyaniline, polypyrrole, and polyparaphenylene. The third type is a type (intercalation, deintercalation or doping, undoping, etc.) in which both lithium cations and anions can enter and exit, such as graphite intercalation compounds and conductive polymers such as polyacene. .

On the other hand, as the negative electrode active material constituting the negative electrode of this type of battery, when metallic lithium is used alone, the electrode potential is the lowest, so that a positive electrode using the above-described positive electrode active material is used. The output voltage of the combined battery is the highest, and the energy density is high, which is preferable.However, dendrites and passive compounds are generated on the negative electrode due to charge and discharge, and there is a problem that deterioration due to charge and discharge is large and cycle life is short. . In order to solve this problem, (1) lithium and Al, Zn, Sn, Pb, Bi, Cd
(2) WO ₂ , MoO ₂ , Fe
Inorganic compounds such as ₂ O ₃ , TiS ₂ , graphite, carbonaceous materials obtained by firing organic materials, etc. Intercalation compounds or insertion compounds in which lithium ions are occluded in the crystal structure, and (3) lithium ion-doped polyacene It has been proposed to use a substance capable of storing and releasing lithium ions, such as conductive polymers such as polyacetylene and polyacetylene.

In general, a battery is constructed by combining a negative electrode using a material capable of inserting and extracting lithium ions other than lithium metal as the negative electrode active material and a positive electrode using the above positive electrode active material. In such a case, since the electrode potential of these negative electrode active materials is more noble than the electrode potential of metallic lithium, there is a disadvantage that the operating voltage of the battery is considerably lower than when metallic lithium is used alone as the negative electrode active material. For example, lithium and Al, Zn, Pb, Sn, B
0.2 to 0.8 V when using an alloy such as i, Cd,
0-1 V, MoO ₂ or W for carbon-lithium intercalation compounds
The lithium ion insertion compound such as O ₂ 0.5-1.5
The V operating voltage decreases. In addition, since elements other than lithium also serve as negative electrode components, the capacity and energy density per volume and weight are significantly reduced.

Further, when an alloy of lithium and another metal described in the above (1) is used, the utilization efficiency of lithium during charging and discharging is low, and cracks occur in the electrodes due to repetition of charging and discharging to cause cracks. Therefore, there is a problem that the cycle life is short due to the generation of the compound. In the case of the lithium intercalation compound or the intercalation compound of (2), deterioration such as collapse of the crystal structure or generation of an irreversible substance due to overcharging and discharging occurs. However, there is a drawback that the output voltage of a battery using this is low because there are many (noble) materials having high (noble). In the case of the conductive polymer of (3),
There is a problem that the charge / discharge capacity, particularly the charge / discharge capacity per volume is small. Further, in conventional lithium secondary batteries, a separator made of a microporous insulating film made of a synthetic resin such as a woven fabric, a nonwoven fabric, and a porous polypropylene film is used, and the separator has a positive electrode layer on one surface, and has a positive electrode layer on the other surface. A battery configuration having a negative electrode layer has been known. The separator holds the electrolytic solution and allows lithium ions to be deposited on the negative electrode through its pores, thereby enabling a battery reaction between the positive and negative electrodes. However, in a conventional lithium secondary battery using a separator made of a porous insulating film, the charge / discharge capacity gradually decreases during repeated charge / discharge, and the cycle life of the battery or the maintenance of the charge / discharge capacity is reduced. There are problems such as poor properties and poor heat resistance with respect to a synthetic resin microporous film.

[0007]

Accordingly, in the present invention, in order to obtain a secondary battery having a high voltage, a high energy density, excellent charge / discharge characteristics, and a long cycle life, the electrode potential with respect to lithium is required. Low (base), there is no deterioration such as the collapse of the crystal structure or the generation of irreversible substances due to the insertion and extraction of lithium ions during charging and discharging, and the amount of lithium ions that can be inserted and extracted reversibly, ie, the effective charge and discharge capacity A larger negative electrode active material is required.

On the other hand, the above-mentioned positive electrode active material of the first type generally has a large energy density, but has a drawback that when overcharged or overdischarged, deterioration due to crystal collapse or generation of irreversible material is large. . On the other hand, the second and third types have the disadvantage that the charge / discharge capacity, particularly the charge / discharge capacity per volume and the energy density are small. For this reason, in order to obtain a secondary battery having excellent overcharge characteristics and overdischarge characteristics, and having a high capacity and a high energy density, there is no crystal collapse or generation of irreversible substances due to overcharge and overdischarge, and it is reversible. It is necessary to use a positive electrode active material having a larger capacity to absorb and release lithium ions.

In addition, a separator which is excellent in ion permeability, has high strength, is thin, has excellent insulating properties, and has excellent heat resistance is required.

[0010]

In order to solve the above-mentioned problems, the present invention provides a negative electrode active material for a battery of this type.
A negative electrode composed of a lithium-containing silicon oxide or silicate, electron-conductive powdery carbon and a resin binder, a positive electrode containing a metal oxide containing a transition metal as a constituent element as an active material, and glass It is proposed to use a separator using a fiber material.

The negative electrode active material contains lithium in the crystal structure or amorphous structure of a silicon oxide or silicate containing lithium, and stores and stores lithium ions by an electrochemical reaction in a non-aqueous electrolyte. A releasable composite oxide of lithium and silicon is used. The state of lithium in the composite oxide is preferably mainly ions, but is not necessarily limited.

The lithium-containing lower oxide Li _x SiO _y containing lithium used as the negative electrode active material of the battery of the present invention.
(However, x> 0, 2>y> 0) As a preferable manufacturing method, the following two methods can be mentioned, but the present invention is not limited thereto. The first method is to synthesize in advance a lithium-free silicon lower oxide SiO _y (where 2>y> 0), and obtain the obtained silicon lower oxide SiO _y and a lithium- or lithium-containing substance. A lithium oxide is absorbed into the lower oxide SiO _y of silicon by the electrochemical reaction of the above to obtain a lower oxide Li _x SiO _y of silicon containing lithium. Examples of such a silicon lower oxide SiO _y include SiO _1.5 (Si ₂ O ₃ ) and S
iO _1.33 (Si ₃ O ₄ ), SiO and SiO _0.5 (Si
_In addition to those having a stoichiometric composition such as ₂ O), any composition having y greater than 0 and less than 2 may be used. These lower oxides of silicon SiO _y can be produced by various known methods as described below. That is, (1) a method of heating silicon dioxide SiO ₂ and silicon Si in a mixed non-oxidizing atmosphere or in vacuum at a predetermined molar ratio, (2) a silicon dioxide SiO _2, such as hydrogen H ₂ reducing gas (3) a method in which silicon dioxide SiO ₂ is mixed with a predetermined amount of carbon C or metal and the like is heated and reduced in a predetermined amount, and (4) silicon gas is oxidized or oxidized. And (5) a CVD method or a plasma CVD method in which a mixed gas of a silicon compound gas such as silane SiH ₄ and oxygen O ₂ is heated or plasma-decomposed and reacted.

On the other hand, as a substance containing lithium for use in an electrochemical reaction, for example, a lithium ion such as a positive electrode active material or a negative electrode active material used in the above-mentioned [Prior Art] is used. Can be used. The absorption of lithium ions by the electrochemical reaction of silicon with the lower oxide SiO _y can be performed in the battery after the battery is assembled, or in the battery or outside the battery in the course of the battery manufacturing process. Can be performed as follows. That is, (1) one of the lower oxides of silicon or a mixture thereof with a conductive agent and a binder formed into a predetermined shape is used as one electrode (working electrode) and contains metallic lithium or lithium. A substance is used as the other electrode (counter electrode) in contact with a lithium ion conductive non-aqueous electrolyte to make the two electrodes face each other to form an electrochemical cell. Lithium ions are chemically absorbed into the lower oxide of silicon. A non-aqueous electrolyte secondary battery is formed by using the obtained working electrode as it is as a negative electrode or as a negative electrode active material constituting the negative electrode. (2) The lower oxide of silicon or a mixture thereof with a conductive agent and a binder is formed into a predetermined shape, and lithium or an alloy of lithium or the like is pressed or brought into contact with the lower electrode to form a laminated electrode. This is incorporated in a non-aqueous electrolyte secondary battery as a negative electrode. In the battery, this laminated electrode contacts the electrolyte to form a kind of local battery,
A method in which lithium is self-discharged and electrochemically occluded in the lower oxide of silicon. (3) A non-aqueous electrolyte secondary battery in which the lower oxide of silicon is used as a negative electrode active material and a material containing lithium and capable of inserting and extracting lithium ions is used as a positive electrode active material. A method in which lithium ions released from a positive electrode by charging during use as a battery are occluded in the lower oxide of silicon.

The second method is a method in which each of lithium and silicon alone or a compound thereof is mixed at a predetermined molar ratio and is heated and synthesized in a non-oxidizing atmosphere or an atmosphere in which oxygen is regulated. . The respective compounds of lithium and silicon as starting materials include oxides, hydroxides, carbonates, salts such as nitrates or organic compounds, etc., which are heated in a non-oxidizing atmosphere to form oxides. Compound is good. In particular, the silicon lower oxide SiO _y shown in the first method is used as the silicon compound, and these are mixed with lithium or a compound having lithium oxygen and heated in an inert atmosphere or vacuum. The method is preferred because it is easy to control, easy to manufacture, and obtains excellent charge / discharge characteristics.

Further, these starting materials may be water, alcohol,
After dissolving or dispersing in a solvent such as glycerin and uniformly mixing or / and reacting in a solution, the solution can be dried and subjected to the above heat treatment. In particular, a predetermined amount of silicon or a lower oxide of silicon or a dispersion or aqueous solution thereof is added to and mixed with an aqueous solution of lithium hydroxide, and the reacted product is dried and dehydrated, and then subjected to the above heat treatment. For example, there is an advantage that a more uniform product can be obtained by a lower temperature heat treatment.

The heating temperature varies depending on the starting material and the heating atmosphere, but synthesis can normally be carried out at 400 ° C. or higher, while at a temperature of 800 ° C. or higher, silicon Si and silicon dioxide SiO ₂ are disproportionated. 400
Temperatures of ~ 800 ° C are preferred. In addition, when various silicic acids having hydrogen as a silicon compound are used as a starting material or when lithium hydroxide or the like is used as a lithium compound, hydrogen is not completely desorbed by heat treatment, and after heat treatment, It is possible that lithium and hydrogen coexist, partly remaining in the product, and are included in the present invention. Furthermore, together with lithium or its compound and silicon or its compound, a small amount of other alkali metals such as sodium, potassium and rubidium, alkaline earth metals such as magnesium and calcium and / or iron, nickel, manganese, vanadium, titanium and lead , Aluminum, germanium, boron, phosphorus, and other metals or non-metallic elements alone or a compound thereof, and then mixed and heat-treated to reduce a small amount of these non-lithium metals or non-metals to lithium and It can coexist with silicon, and these cases are also included in the present invention.

The thus obtained lithium-containing lower oxide of silicon can be used as a negative electrode active material as it is or after being subjected to processing such as pulverization and sizing or granulation as necessary. Further, as in the first method described above, the lower oxide of lithium-containing silicon is formed by an electrochemical reaction between the lower oxide of silicon containing lithium and lithium or a substance containing lithium. Further, lithium ions may be occluded, or conversely, lithium ions may be released from a lower oxide of silicon containing lithium to increase or decrease the amount of lithium, and may be used as the negative electrode active material.

The lithium-containing lower oxide Li _x SiO _y containing lithium thus obtained is used as a negative electrode active material. On the other hand, as the positive electrode active material, as described above, Li _x Mn
O _y or the like of the metal oxide that lithium ions and / or anions absorbing releasably be in used. The lithium-containing silicon oxide of the present invention, particularly the lower oxide Li _x
A negative electrode using SiO _y as a negative electrode active material has the advantages that the electrode potential with respect to metallic lithium is low (base) and the charge / discharge capacity in a low region of 1 V or less is extremely large. By combining with a positive electrode using a (noble) active material having a high electrode potential of 2 V or more, a secondary battery having higher voltage, higher energy density, and excellent charge / discharge characteristics can be obtained. . In particular, a composite oxide having a layered structure containing lithium represented by a composition formula of Li _x MnO _y together with a negative electrode using a negative electrode active material comprising a silicon oxide or a silicate containing lithium according to the present invention. When used in combination with a positive electrode using a positive electrode active material made of a material, a secondary battery with excellent charge / discharge characteristics, especially at high energy density, with little deterioration due to overcharge and overdischarge, and a long cycle life can be obtained. This is particularly preferred.

The composite oxide Li _x MnO _{y of} manganese Mn and lithium used as the positive electrode active material of the battery of the present invention
The preferred production methods include, but are not limited to, the following two methods.

In the first method, the above-mentioned manganese Mn and each of the above-mentioned metal element and lithium Li or their compounds are mixed at a predetermined molar ratio, and the amount of oxygen is controlled in an inert atmosphere or in a vacuum or in a vacuum. This is a method of synthesizing by heating in an atmosphere. Manganese Mn and lithium L as starting materials
As each compound of i, a compound which generates an oxide when heated in an inert atmosphere or in vacuum such as an oxide, a hydroxide, a salt such as a carbonate or a nitrate, or an organic compound is preferable. The heating temperature varies depending on the starting material and the heating atmosphere, but synthesis is usually possible at 400 ° C. or higher, preferably 600 ° C. or higher, more preferably 700 ° C.

The composite oxide of manganese Mn and lithium Li thus obtained can be used as an active material of a positive electrode as it is or after being subjected to processing such as pulverization and sizing as required. Further, in the same manner as in the second method described below, the composite oxide further contains lithium by an electrochemical reaction between the lithium oxide-containing composite oxide and metallic lithium Li or a substance containing lithium. An active material having a lithium content increased or decreased by absorbing ions or conversely releasing lithium ions from the composite oxide may be used as the active material.

The second method, the electrochemical reaction by by occluding lithium ions in the compound oxide MnO _y manganese and lithium and substances containing composite oxide MnO _y and lithium or lithium and the aforementioned manganese This is a method for obtaining the composite oxide. As the substance containing lithium to be used in this electrochemical reaction, for example, a substance capable of inserting and extracting lithium ions as used in the positive electrode active material described in the above-mentioned conventional section can be used.

Such a manganese composite oxide MnO _y
The occlusion of lithium ions by electrochemical reaction into the battery can be performed in the battery after the battery is assembled, or in or outside the battery in the course of the battery manufacturing process, and specifically, performed as follows. I can do it. That is, (1) a manganese complex oxide MnO _y or one electrode that mixed mixture was molded into a predetermined shape thereof with a conductive agent and a binder, and the like (working electrode), containing the metal lithium or lithium The other electrode (counter electrode) is in contact with a lithium ion conductive non-aqueous electrolyte as the other electrode (counter electrode) to make both electrodes face each other to form an electrochemical cell. A method of discharging and electrochemically inserting lithium ions into the composite oxide. A non-aqueous electrolyte secondary battery is constructed using the working electrode obtained as it is as an active material. (2) those composite oxide MnO _y or their conductive agent and manganese and mixtures mixture of binder, and the like and molded into a predetermined shape, and laminated thereto by crimping or contact with lithium or alloys of lithium As an electrode in a non-aqueous electrolyte secondary battery. A method in which the laminated electrode contacts the electrolyte in the battery to form a kind of local battery, self-discharges, and electrochemically occludes lithium in the composite oxide.
(3) The composite oxide MnO _y of manganese as an active material of one electrode, constituting the non-aqueous electrolyte secondary battery using the lithium ion containing lithium to the other electrode as capable of absorbing and releasing material. A method in which lithium ions are occluded in the composite oxide by charging or discharging during use as a battery.

The composite oxide Li _x MnO _y of manganese Mn and lithium Li thus obtained is used as the active material of the positive electrode. On the other hand, the separator of the present invention has excellent ion permeability, high strength, thinness, excellent insulation, and excellent heat resistance, as described in the section of [Problems to be Solved by the Invention]. As a separator, the weight is 70 g / m ² , the thickness is 0.21 mm, and the air permeability is 17 sec.
c, Glass fiber having a tensile strength of 500 g / 15 mm width (or more) and a loss on heating of 10% is used.

The battery of the present invention comprises the above-described negative electrode, positive electrode, and separator. When the negative electrode, the positive electrode, and the separator of the present invention obtained in this manner are used in combination with the electrolytic solution, the charge / discharge characteristics are particularly excellent at a high energy density, and the deterioration due to overcharge and overdischarge is small and the cycle life is short. It is particularly preferable because a long secondary battery can be obtained.

As the electrolyte, γ-butyrolactone,
Propylene carbonate, ethylene carbonate, butylene
Carbonate, dimethyl carbonate, diethyl carbonate
Bonate, methylformate, 1,2-dimethoxye
Tan, tetrahydrofuran, dioxolan, dimethyl
Organic solvent such as formamide alone or mixed solvent
LiClO as decomposition_Four, LiPF₆, LiBF_Four, Li
CF_ThreeSO_ThreeNon-aqueous solution containing lithium ion dissociable salts such as
(Organic) electrolyte, polyethylene oxide or polyphosph
The lithium salt was dissolved in a polymer such as a crosslinked azene.
Polymer solid electrolyte or Li_ThreeInorganic solids such as N and LiI
Lithium ion conductive non-aqueous electrolyte such as body electrolyte
Or non-aqueous electrolysis containing ethylene carbonate (EC)
Liquid can be used. EC has a high freezing point,
It is expected that the volume ratio should be 80% or less based on the total solvent of the solution.
Good. Also, since EC is a high viscosity solvent,
Equation 1 is used to increase conductivity and further stabilize
R · R′-type alkyl carbonate (including R = R ′)
It is also desirable to contain R and R 'are C_nH_{2n + 1}so
In the case where n = 1, 2, 3, 4, 5
In particular, ionic conductivity is particularly high and low viscosity is preferable. During ~
However, R and R 'in Formula 1 are methyl groups (n = 1) or ethyl.
Dimethyl carbonate (DM)
C), diethyl carbonate (DEC) or methyl ethyl
Carbonate and the like are more preferred. In addition, EC and Equation 1
R & R'-type alkyl carbonate represented by
It is desirable to constitute a solvent, and EC and R-R'-type alkyl
When the mixing ratio of the carbonate is about 1: 1 by volume,
The mixing ratio is about 3: 1 to 1% by volume because
It is particularly preferred that the ratio be 1: 3. In addition, the support in the electrolyte
As described above, Li + ion in the solvent
Is a salt that does not directly react with the anode / cathode.
It is good, but for example, LiClO_Four, LiPF₆, LiB
F_Four, LiCF_ThreeSO _Three, Li (CF_ThreeSO_Two)_TwoN etc. are good
No.

FIG. 1 is a sectional view showing an example of a test cell used for evaluating the charge / discharge characteristics of the active material of the nonaqueous electrolyte secondary battery according to the present invention. In the figure, reference numeral 1 denotes a negative electrode case also serving as a negative electrode terminal, which is formed by drawing a stainless steel plate having one outer surface Ni-plated. Reference numeral 3 denotes a negative electrode pellet, a circularly punched lithium foil having a predetermined thickness is pressed on the negative electrode pellet, and 2 is a working electrode current collector made of a conductive adhesive containing carbon. The case 1 was bonded and electrically connected, and these were used as a negative electrode unit. Reference numeral 7 denotes a stainless steel positive electrode case in which one outer surface is Ni-plated, and also serves as a positive electrode terminal. Reference numeral 5 denotes a positive electrode pellet, 6 denotes a working electrode current collector made of a conductive adhesive containing carbon, and bonds and electrically connects the positive electrode 5 and the positive electrode case 7 to form a positive electrode unit. . Reference numeral 4 denotes a separator made of a glass fiber material, which is impregnated with an electrolyte 9. Reference numeral 8 denotes a gasket mainly composed of polypropylene, which is interposed between the negative electrode case 1 and the positive electrode case 7 to maintain the electrical insulation between the negative electrode and the positive electrode, and at the same time, the opening edge of the positive electrode case is bent inward and caulked. The battery contents are hermetically sealed. The electrolyte used was one in which lithium hexafluorophosphate LiPF ₆ was dissolved at 1 mol / l in a mixed solvent of ethylene carbonate and ethyl methyl carbonate at a volume ratio of 1: 1.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention relates to a negative electrode comprising lithium-containing silicon oxide or silicate, electronically conductive carbon powder and a resin binder, and a metal containing a transition metal as a constituent element. The present invention proposes to use a positive electrode using an oxide as an active material and glass fiber as a separator.

<Negative Electrode> For the negative electrode used in the lithium secondary battery of the present invention, lithium or a substance capable of inserting and extracting lithium is used. For example, lithium metal, lithium / silicon, lithium / silicon oxide, and a carbon-based material electrochemically absorbing and releasing lithium ions are exemplified.

As the negative electrode active material, lithium, lithium alloy or a carbon material capable of inserting and extracting lithium ions is used. In these battery systems, when lithium or a lithium alloy is used as a negative electrode active material, by repeating the cycle number, the dissolution and precipitation reaction of lithium is repeated, and eventually needle-like dendritic lithium is formed, There have been problems such as short circuit due to penetration of the diaphragm, capacity deterioration due to detachment from the current collector, and capacity deterioration due to reaction with the electrolyte. Therefore, for the purpose of fundamentally eliminating the formation of these dendrites, the use of a carbon material capable of occluding and releasing lithium ions as a negative electrode active material has been studied, and some of them have been put to practical use.

As the silicon powder constituting the negative electrode, one prepared by pulverization or the like can be used. In addition, silicon that is reduced by electrochemical reaction between silicon oxide and lithium or a substance containing lithium in the battery after battery assembly or in or outside the battery during the battery manufacturing process is used. This is also an effective means. As the negative electrode raw material, a mixture of silicon and silicon oxide may be used.

Various compounds can be included in the silicon powder of the present invention. For example, transition metals (fourth of the periodic table,
5th and 6th period elements from groups III-A to II
An element belonging to Group B), an element belonging to Group IV-B of the Periodic Table,
Alkali metal (elements IA and II-A of the periodic table)
Alternatively, P, Cl, Br, I, and F may be included to form a silicon alloy powder. The amount of the compound to be added is 0 to 20 mol%
Is preferred.

When silicon is used, the equivalent of lithium insertion at the negative electrode is preferably 2 to 4.5 equivalents. When SiO is used, 2.5 to 6.5 equivalents are preferred. Examples of the substance of the present invention for doping silicon or silicon oxide with lithium include lithium metal, lithium alloy, and the like, and calcined carbonaceous compounds capable of inserting and extracting lithium ions or lithium metal. The purpose of using the above lithium metal or lithium alloy together is
The purpose is to reduce silicon oxide and dope lithium in the battery.

<Positive Electrode> Specific examples of the positive electrode material include inorganic compounds such as transition metal oxides containing alkali metals and transition metal chalcogens (iron sulfide, titanium disulfide, molybdenum disulfide, etc.), polyacetylene, polyparaphenylene, and the like.
Examples of the positive electrode used in ordinary secondary batteries include conjugated polymers such as polyphenylenevinylene, polyaniline, polypyrrole, and polythiophene, crosslinked polymers having disulfide bonds, and thionyl chloride.
Among these, in the case of a secondary battery using a non-aqueous electrolyte containing a lithium salt, cobalt, manganese, molybdenum,
Transition metal oxides such as vanadium, chromium, iron, copper, and titanium, and transition metal chalcogens are preferably used. Li
CoO ₂ and LiNiO ₂ are most preferably used because of their high voltage and high energy density.

The positive electrode active material used in the present invention may be a transition metal oxide capable of reversibly inserting and releasing lithium ions, but is particularly preferably a lithium-containing transition metal oxide.
As a preferable lithium-containing transition metal oxide positive electrode active material used in the present invention, an oxide containing lithium-containing Mn is exemplified. Alkali metals other than lithium (elements IA and IIA of the periodic table) and / or Al, G
a, In, Ge, Sn, Pb, Sb, Bi, Si, P,
B or the like may be mixed. The mixing amount is 0 with respect to the transition metal.
~ 30 mol% is preferred. More preferred lithium-containing transition metal oxide positive electrode active material used in the present invention,
Lithium compound / transition metal compound (here, transition metal is Ti, V, Cr, Mn, Fe, Co, Ni, Mo,
W) is a total molar ratio of 0.1.
It is preferable to mix and synthesize so as to be 2 to 3.0. Particularly preferred lithium-containing transition metal oxide positive electrode active materials used in the present invention include lithium compounds / transition metal compounds (where transition metals are V, Cr, Mn, F
It is preferable to mix and synthesize such that the total molar ratio of at least one selected from e, Co, and Ni) is 0.2 to 3.0. Particularly preferred lithium-containing transition metal oxide positive electrode active material used in the present invention is Li _x MnO _y
(Here, a transition metal mainly containing Mn), x = 0.
2 to 1.2, y = 1.4 to 3).
Here, the above-mentioned x value is a value before the start of charge / discharge, and increases / decreases due to charge / discharge.

The positive electrode active material of the present invention may contain one or more transition metal elements, typical elements, and rare earth elements to form a composite metal oxide or a mixture. Particularly preferred dopants are P, Co, Ni, Ti, V, Zr, Nb, M
o, W, Fe, Cr and the like. The average particle size of the positive electrode active material used in the present invention is preferably 500 μm or less,
More preferably 100 μm or less, especially 50 to 0.1 μm
Is good. 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. , Average particle size 0.1
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 a size of not less than 2.5 μm and not more than 2.5 μm are aggregated. Further, it is preferable that 80% or more of the total volume of the primary particle aggregate has a particle size of 1 micron or more and 15 microns or less, more preferably 85% or more of the total volume, and still more preferably 90% or more of the total volume. is there. Specific surface area is 0.05-100
m ² / g, more preferably 0.1 to 50 m ² /
g, especially 0.1 to 30 m ² / g.

Further, two or more kinds of the positive electrode active materials of the present invention can be used as a mixture. The present invention can be applied to a case where the voltage range to be used is changed or the remaining capacity is detected by the voltage. <Electrode Shape / Forming Method> The electrode shape can take various shapes such as a plate shape, a film shape, a column shape, or a shape formed on a metal foil, depending on a target battery. The method of integrating the carbon fiber and the electrode plate is not particularly limited. For example, first, the carbon fiber is formed into a sheet by uniaxially aligning the carbon fiber, and the carbon fiber formed into a sheet by a roll press or the like. And a method of bonding sheet-like carbon fibers to the metal foil using a binder.

<Separator> A conventional separator is a porous material having a continuous air-permeable hole having no electron conductivity with respect to an electrolytic solution or an electrode active material, and is made of a cloth or nonwoven cloth made of polyethylene or polypropylene. Alternatively, a porous insulating film is used. The pore size of the separator is generally used for batteries.

The separator used in the present invention is a glass fiber in the form of a woven fabric, a nonwoven fabric or a porous material, and has a weight of 60%.
To 80 g / m ^2, a thickness of 0.10 to 0.30 mm, air permeability of 10～25Sec, tensile strength 400g or more / 15 mm
Materials having a width and a loss on heating of 5 to 15% are preferred. The separator is fixed in the battery case so as not to cause a practical problem.

<Conductive Agent> 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 material 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,
Ketjen black, carbon fiber, etc. are used. As the metal, metal powder such as copper, nickel, and silver, and metal fibers are used. Conducting polymers are also used. The mixing ratio varies depending on the electric conductivity of the active material, the shape of the electrode, and the like, but it is appropriate to add 2 to 40% to the active material.

<Binder> 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 -Propylene-diene terpolymer (EPDM), sulfonated E
PDM, styrene butadiene rubber, polybutadiene, fluoro rubber, polyethylene oxide, polyimide, epoxy resin, polysaccharides such as phenol resin, thermoplastic resin,
A thermosetting resin, a polymer having rubber elasticity, 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. In particular, when the active material is used for an active material having a large lithium storage capacity, a large amount of 5 to 40% by weight is preferable because a structural change and a volume change are caused by charge and discharge.

<Filler> 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. The amount of the filler added is not particularly limited, but is preferably 0 to 30% by weight.

<Electrolyte> The electrolyte is not particularly limited, and an organic solvent used in a conventional nonaqueous secondary battery is used. As the organic solvent, cyclic esters, chain esters, cyclic ethers, chain ethers, and the like are used. Specifically, propylene carbonate (PC), ethylene carbonate (EC), butylene carbonate (BC) , Vinylene carbonate, dimethyl carbonate (DMC), diethyl carbonate (DEC), γ-
Butyrolactone (γBL), 2-methyl-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 Butylpropyl carbonate, alkyl propionate, dialkyl malonate, alkyl acetate, tetrahydrofuran (THF), alkyltetrahydrofuran, dialkylalkyltetrahydrofuran, alkoxytetrahydrofuran, dialkoxytetrahydrofuran, 1,3-dioxolan, alkyl-1,3- Geo SORUN, 1,4-dioxolane,
2-methyltetrahydrofuran, dimethyl sulfoxide, 1,3-dioxolan, formamide, dimethylformamide, dioxolan, acetonitrile, nitromethane, methyl formate, methyl acetate, methyl propionate,
Organic solvents such as ethyl propionate and phosphoric acid triester, and derivatives and mixtures thereof are preferably used.

From the viewpoint of suppressing the reductive decomposition reaction of the solvent, use of an electrolytic solution in which carbon dioxide (CO ₂ ) is dissolved is effective in improving the capacity and cycle life. Main impurities present in the mixed solvent (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, high temperature (6
(0 ° C. or higher) Self-discharge during 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 50 ppm or less, and the organic peroxide content is 100 ppm.
It is preferably 0 ppm or less <Solid electrolyte> In addition to the electrolytic solution, the following solid electrolyte can be used. 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. As 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 phosphate polymer, or the like is effective. A method using both an inorganic and an organic solid electrolyte is also known.

<Conductive Salt> Examples of the electrolyte contained in the electrolytic solution include alkali metal, especially lithium halide, perchlorate, thiocyanate, borofluoride, and phosphorus fluoride.
Arsenic fluoride, aluminum fluoride, trifluoromethyl sulfate and the like are preferably used. As the supporting salt, lithium perchlorate (LiClO ₄ ), lithium hexafluorophosphate (LiPF ₆ ), lithium borofluoride (LiB
F ₄ ), lithium arsenic hexafluoride (LiAsF ₆ ), lithium trifluorometasulfonate (LiCF ₃ SO ₃ ), lithium bistrifluoromethylsulfonylimide [Li
One or more salts such as lithium salts (electrolytes) such as N (CF ₃ SO ₂ ) ₂ ] can be used. The amount dissolved in the non-aqueous solvent is desirably 0.5 to 3.0 mol / 1.

In particular, those containing EC, DEC and LiClO ₄ have little swelling at high temperature storage, and
Those containing C, DME and LiClO ₄ had low internal resistance and good cycle characteristics. Li for EC and EMC
PF ₆ plus PC, EC, DME with Li
The sample to which ClO ₄ was added also had low internal resistance and good cycle characteristics.

<Electrolyte Additive> An additive may be added for the purpose of improving discharge and charge / discharge characteristics. Although it may be added directly to the active material, the most common method is to add it to the electrolytic solution. For example, toluene, pyridine (Japanese Unexamined Patent Publication No.
9-108, 525), triethylphosphite (JP-A-47-4,376), triethanolamine (JP-A-52-72,425), and cyclic ether (JP-A-57-425).
152,684), ethylenediamine (JP-A-58-8)
7,777), n-glyme (JP-A-58-87,77)
8), hexaphosphoric acid triamide (JP-A-58-877)
79), nitrobenzene derivatives (JP-A-58-214,
281), sulfur (JP-A-59-8,280), quinone imine dye (JP-A-59-68,184), N-substituted oxazolidinone and N, N'-substituted imidazolidinone (JP-A-59-154, 778), ethylene glycol dialkyl ether (JP-A-59-205,167), quaternary ammonium salts (JP-A-60-30,065), polyethylene glycol (JP-A-60-41,773), Pilo
(JP-A-60-79,677), 2-methoxyethanol (JP-A-60-89,075), AlCl3 (JP-A-61-88,466), a conductive polymer-electrode active material monomer -(JP-A-61-161,673), triethylene phosphoramide (JP-A-61,208,758), trialkylphosphine (JP-A-62-80,976),
Morpholine (JP-A-62-80977), aryl compounds having a carbonyl group (JP-A-62-8667)
3), hexamethylphosphoric triamide and 4-alkylmorpholine (JP-A-62-217575), bicyclic tertiary amine (JP-A-62-217578), oil (JP-A-62-217578) -287,580), quaternary phosphonium salts (JP-A-63-121268), tertiary sulfonium salts (JP-A-63-121269) and the like.

<Non-flammable High Temperature Additive> A halogen-containing solvent such as carbon tetrachloride or ethylene trifluoride chloride can be contained in the electrolyte to make the electrolyte non-flammable. (Japanese Unexamined Patent Publication (Kokai) No. 48-36,632) Further, in order to provide suitability for high-temperature storage, an electrolytic solution can contain carbon dioxide. (Japanese Unexamined Patent Publication (Kokai) No. 59-134,567) The mixture of the positive electrode and the negative electrode may contain an electrolytic solution or an electrolyte. For example, a method is known in which the ionic conductive polymer, nitromethane (JP-A-48-36,633), and an electrolytic solution (JP-A-57-124,870) are included.

<Surface Modification of Positive Electrode> The surface of the positive electrode active material can be modified. For example, the surface of a metal oxide is treated with an esterifying agent (JP-A-55-16377).
9) or treatment with a chelating agent (JP-A-55-16)
3,780), a conductive polymer (JP-A-58-1631,1).
88, 59-14, 274) and polyethylene oxide (JP-A-60-97,561). Further, the surface of the negative electrode active material can be modified. For example, it is possible to provide an ion-conductive polymer or a polyacetylene layer (Japanese Patent Application Laid-Open No. 58-111,276), or to perform treatment with LiCl (Japanese Patent Application Laid-Open No. 58-142,771).

<Current Collector> As the current collector of the electrode active material,
A metal plate or a metal foil having low electric resistance is preferred. For example, for the positive electrode, in addition to materials such as stainless steel, nickel, aluminum, titanium, tungsten, gold, platinum, and calcined carbon, those obtained by treating the surface of aluminum or stainless steel with carbon, nickel, titanium, or silver are used. 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,
Examples include PVD, cladding by pressure bonding, and coating.

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.

Although the surface of these materials may be oxidized, benzotriazole, triazine thiol, alkyl thiol, a fluorine-based water-producing agent, a silicon-based water-producing agent, or the like may be used as a rust preventive treatment. As the shape, a foil, a coin button battery can, a film, a sheet, a net, a punched material, a lath body, a porous body, a foamed body, a molded body of a fiber group, and the like are used. The thickness is not particularly limited. In the case of a coin button battery can, terminals are mounted by resistance welding, laser welding, or the like to be mounted on a substrate. The material of the terminal includes stainless steel, stainless / nickel clad material, stainless steel plated with nickel or gold, etc., and is not particularly limited as long as it is a metal.

<Conductive Adhesive> 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 a sheet-shaped electrode, it is used for the purpose of electrical connection rather than physically bonding the current collector and the electrode.

<Gasket> When used as a coin or a button battery, polypropylene, polyethylene, polyamide resin and various engineering plastics are used as the gasket. Usually, polypropylene is generally used, but a material such as engineering plastic having a high heat-resistant temperature may be used in order to cope with a reflow temperature when a battery is mounted on a substrate.

<Sealant> 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, etc. is used between the gasket and the positive / negative electrode can. . 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.

<Battery Shape> The shape of the battery can be applied to any of coins, buttons, sheets, cylinders, corners and the like. When the shape of the battery is a coin or a button, the mixture of the positive electrode active material and the negative electrode active material is mainly used after being compressed into a pellet shape. 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.

The shape of the battery is a sheet, a cylinder,
In the case of a corner, the mixture of the positive electrode active material and the negative electrode active material is mainly used after being coated on a current collector, dried, and compressed. The coat thickness, length and width are determined by the size of the battery, but the thickness of the coat is in a compressed state after drying,
1 to 2000 μm is particularly preferred. As a method for pressing pellets and sheets, a method generally used can be used, but a die pressing method and a calendar pressing method are particularly preferable. The pressing pressure is not particularly limited.
t / cm ² is preferred. The press speed of the calender press method is preferably 0.1 to 50 m / min. The pressing temperature is preferably from room temperature to 200 ° C.

<Battery Application> The application of the non-aqueous secondary battery of the present invention is not particularly limited. For example, when the non-aqueous secondary battery is mounted on an electronic device, a color notebook computer, a black-and-white notebook computer, a pen-input personal computer, a pocket (palmtop) ) PCs, notebook word processors, pocket word processors,
E-book player, mobile phone, cordless phone handset, pager, handy terminal, mobile fax, mobile copy, mobile printer, headphone stereo, video movie, LCD TV, handy cleaner, portable CD, mini disk, electric shaver,
Electronic translators, car phones, transceivers, power tools,
Electronic organizer, calculator, memory card, tape recorder,
Radios, backup power supplies, memory cards, and the like. Other consumer products include automobiles, electric vehicles, motors, lighting equipment, toys, game machines, road conditioners, irons, watches, strobes, cameras, medical equipment (pacemakers, hearing aids, shoulder massagers, etc.). Furthermore, it can be used for various military purposes and space applications. Further, it can be combined with a solar cell.

The secondary battery using the electrode of the present invention can be used for video cameras, personal computers, word processors, radio cassettes,
It can be widely used for portable small electronic devices such as mobile phones. The use of the non-aqueous electrolyte secondary battery of the present invention is not particularly limited. For example, a backup power supply for a mobile phone, a pager, and the like. Power supply for wristwatch with power generation function. Hereinafter, the present invention will be described in more detail with reference to examples.

<Parts Drying> 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 350C, particularly preferably in the range of 100 to 250C. The water content of the entire battery is preferably 2000 ppm or less, and the positive electrode mixture, the negative electrode mixture and the electrolyte are each preferably 50 ppm or less from the viewpoint of cycleability.

[0061]

EXAMPLE In this example, a lithium-containing manganese oxide was used as a positive electrode active material and a lithium-containing silicon oxide was used as a 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.

The positive electrode was produced as follows. Commercial L
i0.36MnO2.43 (containing P) was ground and mixed with graphite as a conductive agent and polyacrylic acid as a binder in a weight ratio of 88.5: 9: 2.5 to form a positive electrode mixture. Next, this positive electrode mixture was pressure-formed at ² ton / cm ² into pellets having a diameter of 4.05 mm. Thereafter, the positive electrode pellet 5 thus obtained is bonded and integrated with the positive electrode case 7 using an electrode current collector 6 made of a conductive resin adhesive containing carbon, and then dried by heating under reduced pressure at 150 ° C. for 8 hours. did.

The negative electrode was manufactured as follows. Commercially available silicon or silicon oxide SiO is automatically mortared to a particle size of 44.
A material pulverized and sized to not more than μm was used as an active material of a negative 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: 2.
The mixture was mixed at a ratio of 1.5: 7 to form a negative electrode mixture. Then, the mixture was press-formed at ² ton / cm ² into a pellet having a diameter of 4.05 mm to obtain a negative electrode pellet 3. Thereafter, the negative electrode pellet 3 thus obtained is bonded and integrated with the negative electrode case 1 using an electrode current collector 2 made of a conductive resin adhesive containing carbon as a conductive filler. The mixture was dried by heating under reduced pressure for hours. Further, a punched lithium foil 10 having a diameter of 4 mm was pressed on the pellet to form a lithium-negative electrode pellet laminated electrode.

The separator is made of 4 glass fiber nonwoven fabric having a diameter of 4
mm, and this was used as a separator. This separator is disposed between the positive and negative electrodes. Electrolyte solution 9 used was one in which LiClO ₄ was dissolved at 1 mol / l in a mixed solvent of ethylene carbonate and diethyl carbonate at a volume ratio of 1: 2. Discharge characteristics when the battery thus prepared was subjected to a charge / discharge cycle at a constant current of 25 μA, a discharge (D) cutoff voltage of 2.0 V and a charge (C) cutoff voltage of 3.3 V for 24 hours. Is shown in FIG.

Similarly, the discharge characteristics of the battery using the conventional separator are shown in FIG. The battery of the present invention and the conventional battery have a long-term cycle performance.The battery of the present invention repeats a stable cycle and has a small drop in capacity. You can see that. In particular, when the number of cycles exceeds 100, the difference becomes large.

[0066]

As described in detail above, the present invention comprises powdered silicon or a silicon alloy, electronically conductive powdered carbon, and a resin binder as a negative electrode active material of a nonaqueous electrolyte secondary battery. A negative electrode, a positive electrode using a metal oxide containing a transition metal as a constituent element as an active material, and a glass fiber as a separator can provide an excellent nonaqueous electrolyte secondary battery.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an example of a battery structure used for performance evaluation of the present invention.

FIG. 2 is an explanatory diagram showing cycle characteristics of a battery according to the present invention and a conventional battery.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 negative electrode case 2 electrode current collector 3 negative electrode pellet 4 separator 5 positive electrode pellet 6 electrode current collector 7 positive electrode case 8 gasket 9 electrolyte 10 lithium foil

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI H01M 4/58 H01M 4/58 (72) Inventor Kensuke Tahara 1-8-8 Nakase, Mihama-ku, Chiba-shi, Chiba Seiko Electronic Industry Co., Ltd. (72) Inventor Sagio Tsugio 1-8-1 Nakase, Mihama-ku, Chiba-shi, Chiba Seiko Electronic Industry Co., Ltd.

Claims (5)

[Claims] A negative electrode comprising lithium-containing silicon oxide or silicate, electron-conductive powdery carbon, and a resin binder; and a metal oxide containing a transition metal as a constituent element. A non-aqueous electrolyte secondary battery comprising: a positive electrode; and a glass fiber material as a separator. 2. The composition formula Li _x SiO as a negative electrode active material.
_2. The non-aqueous solution according to claim 1, which is represented by _y (where x ≧ 0, 2>y> 0), and which is reduced by an electrochemical reaction with lithium or a substance containing lithium. Electrolyte secondary battery. 3. The method according to claim 1, wherein the negative electrode is formed in a battery after battery assembly or in or outside the battery during the battery manufacturing process, by an electrochemical reaction with lithium or a substance containing lithium. 2. The non-aqueous electrolyte secondary battery according to claim 1, wherein the non-aqueous electrolyte secondary battery is a lithium-containing silicon oxide or silicate obtained by storing lithium in silicate. 4. The positive electrode is a lithium-containing manganese oxide Li _x MnO _y (2 <y <3), and the maximum amount of lithium entering the positive electrode during charging and discharging is in the range of 0.2 <x <0.8, and the operating voltage range 2. The non-aqueous electrolyte secondary battery according to claim 1, wherein the center of the battery is 3.5 to 0.8 V. 5. A separator having an average fiber diameter of 10 μm or less, a thickness of 5 to 300 μm, and a basis weight of 1.0 to 100 g /
^2. The non-aqueous electrolyte secondary battery according to claim 1, wherein glass fibers having m ² and an average diameter of 10 μm or less are used.