JPH11185744A - Nonaqueous electrolyte battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a safe and high output type battery capable of being charged rapidly, showing an excellent charge and discharge cycle characteristics with high voltage and high energy density by using an ultra fine particle active material made of silicon as a main component of a negative electrode active material. SOLUTION: Silicon having the particle diameter of about 0.1-0.01 μm is used as a main component of a negative electrode active material. Preferably, as a main component soluble material of nonaqueous electrolyte, salt containing carbon is used, and as a main component material of a positive electrode active material, a lithium contained transient metal oxide is used. As the salt containing carbon of nonaqueous electrolyte, one represented by a formula of (R1SO2 )(R2SO2 )NLi, where R1, R2 are shown by CnF2n+1 (n is 1-4, R1=R2 or R1≠R2) is desirable. Preferably, R1=R2=CF3 or C2 F5 or R1=CF3 , R2=C4 F9 . The negative electrode active material is turned into ultra fine particles to restrain the fineness of crystal made at the time of absrobing and discharging lithium, resulting in improvement of charge and discharge efficiency.

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 battery, and more particularly to a negative electrode active material and an electrolyte used in the battery.

[0002]

2. Description of the Related Art Conventionally, lithium has been typically used as a negative electrode active material for a nonaqueous electrolyte battery. However, dendritic deposition of lithium generated during charging (dendrite)
Therefore, there was a problem in terms of cycle life. In addition, the dendrite penetrates through the separator, causing an internal short circuit and causing ignition.

Also, aluminum-lithium alloys and the like have been used for the purpose of preventing dendrite generated at the time of charging as described above. However, when the charged amount is increased, problems such as fine powdering of the negative electrode and falling off of the negative electrode active material are caused. was there.

At present, batteries using a carbon material for the negative electrode have been attracting attention for their long life and safety, and some of them have been put to practical use. However, the carbon material used for the negative electrode is
At the time of quick charging, there was a problem that an internal short circuit or a reduction in charging efficiency occurred. Since these carbon materials generally have a lithium doping potential of the carbon material close to 0 V, when rapid charging is performed, the potential becomes 0 V or less and lithium may be deposited on the electrode. For this reason, it causes internal short circuit of the cell and lowers the discharge efficiency. Also,
Although such carbon materials have been significantly improved in terms of cycle life, their relatively low density results in low capacity per volume. That is, this carbon material is still insufficient in terms of high energy density. In addition, in the case where a film needs to be formed on carbon, the initial charge / discharge efficiency decreases, and the amount of electricity used for forming the film is irreversible, which leads to a reduction in capacity corresponding to the amount of electricity. Therefore, development of a safe negative electrode material for a non-aqueous electrolyte battery with a higher capacity, a higher energy density, a longer cycle life, and the like is desired.

[0005]

As an alloy of lithium and silicon, Binary Alloy Pha has already been used.
As in se Diagrams (p2465),
It is known to alloy with compositions up to Li ₂₂ Si ₅ . Japanese Patent Application Laid-Open No. Hei 5-74463 reports that a single crystal of silicon is used for a negative electrode. The use of silicon as a battery material is one of inexpensive and safe materials because of its abundant resources and low toxicity. However, when attempting to dope lithium into a single crystal of silicon as a negative electrode material of a nonaqueous electrolyte battery for rapid charge / discharge, it was found that lithium was deposited with almost no doping. Further, the low-temperature performance of this silicon single crystal is poor, and when an electrolyte using a Lewis acid salt such as LiBF ₄ is used as a solute, the charge / discharge efficiency of each cycle is low, and cycle deterioration occurs.

That is, when lithium metal or an alloy of lithium and a metal is used as the negative electrode, there are advantages in terms of high voltage, high capacity, and high energy density, but there are problems in cyclability and safety. When using materials,
Although it is advantageous in terms of high voltage and safety, it is insufficient in terms of high capacity and high energy density. When silicon, which is expected to have high capacity and high energy density, is used as the negative electrode active material, it is difficult to rapidly charge and discharge at high output, and the charge / discharge efficiency of each cycle is low, leading to cycle deterioration. .

For this reason, high voltage, high energy density,
To obtain a non-aqueous electrolyte battery with excellent charge-discharge cycle characteristics, rapid charging, high output, and high safety, changes in the crystal system and volume change during insertion and extraction of lithium during charging and discharging. There is a demand for a conductive compound which is small, capable of rapid charging and high-power discharge, excellent in low-temperature characteristics, and capable of reversibly inserting and extracting lithium.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and it is an object of the present invention to use an ultrafine particle active material as a main component of a negative electrode active material used in a non-aqueous electrolyte battery. Features. Preferably, the ultrafine particle active material is silicon, in the nonaqueous electrolyte battery, a salt containing carbon is used as a main constituent solute of the electrolyte, and the main constituent material of the positive electrode active material is a lithium-containing transition metal oxide. desirable.

Furthermore, salts containing carbon listed above, characterized by comprising the following general formula _{(1) (R1 SO 2)} (R2 SO 2) NLi ···· general formula (1). Preferably the general formula (1) R1 in, R2 is represented by C _n F _{2n + 1, n} is a number from 1 to 4, it is desirable that R1 = R2 or R1 ≠ R2.

Here, in a non-aqueous electrolyte battery, when LiBF ₄ or LiPF ₆ which has been generally used in the past is used as an electrolyte, it has excellent ionic conductivity, but when decomposed, generates hydrogen fluoride and the like. I know that. When the ultrafine particle active material is used as a negative electrode active material using these solutes, impurities generated from the solute react with the film present on the surface of the ultrafine particle active material, and the surface film has high electric resistance and poor ion conductivity. It turned out to change into a coating. Therefore, it is conceivable that the electrode resistance increases each time charging / discharging is performed, which lowers the charging / discharging efficiency, thereby leading to cycle deterioration.

On the other hand, it has been found that salts containing carbon are hardly decomposed and hardly release hydrogen fluoride or the like even in the reaction with water. Therefore, when the ultrafine particle active material is used as the negative electrode active material, it is considered that the increase in the electric resistance of the surface coating and the decrease in the ionic conductivity are suppressed, the charge / discharge efficiency is improved, and the cycle characteristics are improved. Can be Conventionally,
Although an alloy of silicon and lithium was known, the volume change upon insertion and extraction of the lithium was large, and the active material crystal became finer, resulting in isolation of the active material.
The charge / discharge efficiency was reduced. As a result, this is one of the causes of large cycle deterioration. Thus, the present inventors have found that the anode active material is made into ultrafine particles, and by suppressing crystal refinement upon insertion and extraction of lithium, charge and discharge efficiency is improved, and as a result, cycle characteristics are improved. The present invention has been reached. Further, it was also found that the use of the ultrafine particle negative electrode active material of the present invention enabled high-power discharge and excellent low-temperature characteristics.

[0012]

Embodiments of the present invention will be described below.

The ultrafine particle active material used in the present invention may be any material capable of inserting and extracting lithium. For example, an element which can be alloyed with lithium, such as an alkaline earth metal, a transition metal, a nonmetal simple substance, an oxide, a nitride, a sulfide, a phosphate and the like can be mentioned. Preferably, silicon, arsenic,
It is an alloy containing aluminum, tin, antimony, lead, and carbon as main components, and most preferably silicon because of its large lithium storage capacity.

The ultrafine particle active material used in the present invention is preferably particles having a particle size of 0.1 to 0.01 μm. The method for producing the ultrafine particle active material includes a vapor deposition method, an argon sputtering method, an ion coater method, a plasma CVD method, a photo CVD method, and a thermal C method.
VD method, quenching method, thermal plasma method, pulverization and classification are used. As a pulverizing method, for example, a mortar, a ball mill, a sand mill, a vibrating ball mill, a planetary ball mill, a jet mill, a counter jet mill, a swirling air jet mill, a sieve and the like are used. At the time of pulverization, wet pulverization in which an organic solvent such as water or hexane coexists can be used. The classification method is not particularly limited, and a sieve, an air classifier, or the like is used as needed in both dry and wet methods.

When these ultrafine particle active materials are used as a negative electrode, for example, a method of directly obtaining an ultrafine particle active material layer by using an argon sputtering method on a current collector, or grinding the ultrafine particle active material obtained by rapid cooling is used. Then, a method of kneading with a binder or a conductive material and coating the current collector on the current collector may be used. In particular, a method of forming an ultrafine particle active material layer directly on a current collector is preferable because a binder, a conductive material, and a coating operation are not required.

It has also been found that an ultrafine particle active material having excellent electron conductivity is suitable for alloying with lithium. In particular electronic conductivity at room temperature 10 ^-5 Scm ^-1 or more, preferably, it has been found that some 1Scm ^-1 or more is excellent in charge and discharge characteristics. For example, silicon is originally a semiconductor, but when it is used as a main component of a negative electrode active material, the flow of electrons between the active material and the current collector is important. That is,
By doping impurities into silicon, which is a semiconductor, a foreign semiconductor, in particular, a p-type semiconductor, an n-type semiconductor,
By using a semiconductor having an n-junction, a semiconductor having good electron conductivity can be obtained, and characteristics with more excellent charge and discharge characteristics can be obtained as a negative electrode active material. The term “impurity” as used herein means any of the elements in the periodic table that can be a donor atom or an acceptor atom, but is preferably P, Al, or A.
s, Sb, B, Ga, In, etc., most preferably B
However, the present invention is not limited to these. Further, it is considered that the presence of lattice defects also contributes to the improvement of electron conduction. Examples of the impurity doping method include, but are not limited to, a method using silicon in which impurities are mixed in advance as a target of an argon sputter, an alloy method, a diffusion method, and an ion implantation method. Regarding the concentration of impurity addition, usually,
0 While the ^seven to 10 ⁶ is the ratio of one donor atom or acceptor atoms, preferably has a high concentration of doping suitable donor atom or the acceptor atom a rate of one per 10 ⁴ silicon atoms or, It is desirable that the concentration be as high as described above.

The negative electrode material that can be used in conjunction with the present invention includes lithium metal, lithium alloy, etc., calcined carbonaceous compounds capable of inserting and extracting lithium ions or lithium metal, chalcogen compounds, and lithium such as methyllithium. Organic compounds and the like can be mentioned. In addition, by using lithium metal, a lithium alloy, and an organic compound containing lithium in combination, lithium can be inserted into the ultrafine particle active material used in the present invention inside the battery.

When the ultrafine particles of the present invention are used as a powder, a conductive agent, a binder, a filler or the like can be added as an electrode mixture. Any conductive material may be used as long as it does not adversely affect battery performance. Usually, natural graphite (flaky graphite, flaky graphite, earthy graphite, etc.), artificial graphite, carbon black, acetylene black, Ketjen black, carbon whiskers, carbon fibers and metals (copper, nickel, aluminum, silver, gold, etc.)
A conductive material such as powder, metal fiber, metal deposition, and conductive ceramic material can be included as one type or a mixture thereof. Among these, the combined use of graphite, acetylene black and Ketjen black is desirable. The addition amount is preferably 1 to 50% by weight, particularly preferably 2 to 30% by weight.

As the binder, usually, tetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, ethylene-propylene diene terpolymer (EPDM), sulfonated EPDM, styrene butadiene rubber (SBR), fluoro rubber, carboxymethyl cellulose, etc. Such as a thermoplastic resin, a polymer having rubber elasticity, a polysaccharide and the like can be used alone or as a mixture of two or more. Further, it is desirable that a binder having a functional group that reacts with lithium, such as a polysaccharide, be deactivated by, for example, methylation. The addition amount is preferably 1 to 50% by weight, particularly 2 to 50% by weight.
30% by weight is preferred.

As the filler, any material may be used as long as it does not adversely affect battery performance. Usually, olefin polymers such as polypropylene and polyethylene, aerosil, zeolite, glass, carbon and the like are used. The added amount of the filler is preferably 30% by weight or less.

The current collector of the electrode active material may be any current collector that does not adversely affect the battery structure. For example, as a current collector material for the positive electrode, aluminum, titanium, stainless steel, nickel, calcined carbon, conductive polymer, conductive glass and the like, as well as adhesion, conductivity,
For the purpose of improving oxidation resistance, a material obtained by treating the surface of aluminum, copper, or the like with carbon, nickel, titanium, silver, or the like can be used. Copper, stainless steel, nickel, aluminum, titanium, calcined carbon,
In addition to carbon fiber, conductive polymer, conductive glass, Al-Cd alloy, etc., for the purpose of improving adhesion, conductivity, and oxidation resistance,
A material obtained by treating the surface of a group of copper or carbon fibers with carbon, nickel, titanium, silver, or the like can be used. Further, a film formed by depositing copper, platinum, gold, silver, or the like on a film of an olefin polymer such as polyethylene or polypropylene, or a film of polyimide can be used. These materials can be oxidized on the surface. For these shapes, in addition to foils produced by rolling or electrolysis, films, sheets, nets, punches, expanded ones, laths, porous bodies, foamed bodies, formed bodies of fiber groups, and the like are used. The thickness is not particularly limited, but a thickness of 1 to 500 μm is used.

On the other hand, MnO ₂ , M
oO ₃ , V ₂ O ₅ , Li _x CoO ₂ , Li _x NiO ₂ ,
Metal oxides such as Li _x Mn ₂ O ₄ , TiS ₂ , MoS
₂ , metal chalcogenides such as NbSe ₃ , polyacene,
Graphite intercalation compounds such as polyparaphenylene, polypyrrole, and polyaniline, and various substances capable of absorbing and releasing alkali metal ions and anions such as conductive polymers can be used.

In particular, when the ultrafine particle active material of the present invention is used as a negative electrode active material, V
₂ O ₅ , MnO ₂ , Li _x CoO ₂ , Li _x NiO ₂ ,
Those having an electrode potential of 3 to ₄ V, such as Li _x Mn ₂ O _4, are desirable. In particular, Li _x CoO ₂ , Li _x NiO ₂ , L
i _x Mn lithium-containing transition metal oxides such as ₂ O ₄ are preferred.

As the electrolyte, for example, an organic electrolyte, a polymer solid electrolyte, an inorganic solid electrolyte, a molten salt, or the like can be used, and among them, an organic electrolyte is preferable. As the organic solvent of the organic electrolyte, propylene carbonate, ethylene carbonate, butylene carbonate, diethyl carbonate, dimethyl carbonate, methyl ethyl carbonate, esters such as γ-butyrolactone, tetrahydrofuran, substituted tetrahydrofuran such as 2-methyltetrahydrofuran, dioxolane, Ethers such as diethyl ether, dimethoxyethane, diethoxyethane, methoxyethoxyethane, dimethylsulfoxide, sulfolane, methylsulfolane,
Acetonitrile, methyl formate, methyl acetate, N-methylpyrrolidone, dimethylformamide and the like can be mentioned, and these can be used alone or as a mixed solvent.

As the main constituent solute of the electrolyte used in the present invention, a salt containing carbon is preferable. For example, Japanese Patent Application Laid-Open
Formula used in JP-A-225045: (C _n X
_{2n + 1} Y) ₂ N ⁻ , M ⁺ , and the following general formulas (2) and (3): (RSO ₂ ) ₃ C ⁻ , M ⁺ ... General formula (2) (RSO ₂ ) O ^- , M ⁺ ... It is preferable to use a compound represented by the general formula (3). Further preferably be those represented by the following general formula _{(1) (R1 SO 2)} (R2 SO 2) NLi ···· general formula (1).

In the above formula, Y is SO ₂ or CO, and R is C _n
F _{2n + 1} , R ₁ and R 2 are C _n F _{2n + 1} , where n is 1 to 4
R1 = R2 or R11R2. Most preferably _{R1 = R2 = CF 3, R1} = R2 = C 2 F
_5, or R1 = CF _3, R2 = a C ₄ F _9.

On the other hand, as the solid electrolyte, for example, an inorganic solid electrolyte, an organic solid electrolyte, an inorganic organic solid electrolyte, a molten salt and the like can be used. Well known inorganic solid electrolytes include lithium nitrides, halides, oxyacid salts, phosphorus sulfide compounds, and the like, and one or more of these can be used in combination. 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,
xLi ₃ PO _{4- (1-x)} Li ₄ SiO ₄ , Li ₂ SiS ₃
Etc. are effective. On the other hand, in an organic solid electrolyte, a polyethylene oxide derivative, a polymer containing at least the derivative, a polypropylene oxide derivative, a polymer containing at least the derivative, polyphosphazene or the derivative, a polymer containing an ion dissociating group, a phosphate ester polymer derivative Further, a polymer matrix material (gel electrolyte) in which a non-aqueous electrolyte is contained in a polyvinyl pyridine derivative, a bisphenol A derivative, polyacrylonitrile, polyvinylidene fluoride, fluorine rubber, or the like is effective.

As the separator, an insulating thin film having excellent ion permeability and mechanical strength can be used. Olefin polymers such as polypropylene and polyethylene, glass fiber, and organic solvent resistant and hydrophobic
Sheets, microporous membranes, nonwoven fabrics, cloths, and the like made of polyvinylidene fluoride, polytetrafluoroethylene, and the like are used. The pore size of the separator is in a range generally used for a battery, and is, for example, 0.01 to 10 μm.
The same applies to the thickness, which is in the range generally used for batteries, for example, 5 to 300 μm.

In the ultrafine particle active material of the present invention, a conductive adhesive layer may be provided between the current collector and the active material for the purpose of collecting current. Usually silver paste as conductive adhesive,
Carbon paste is used. Further, by plating a part of the crystal with nickel, it is possible to join with a molten metal such as solder or silver brazing.

As described above, the present invention provides a non-aqueous electrolyte battery using at least 0 to 2 with respect to metallic lithium by using an ultrafine particle active material as a main constituent material of a negative electrode active material.
Can absorb and release lithium ions in the range of V,
In addition, since the negative electrode active material is ultrafine particles, fine powdering at the time of charge and discharge and partial isolation of the negative electrode active material, which are observed in ordinary alloys, are suppressed, and low-temperature characteristics are improved. Furthermore, by using a salt containing carbon as the main constituent solute of the electrolyte,
It can be used as a negative electrode of a non-aqueous electrolyte battery having excellent charge / discharge efficiency, excellent cycle characteristics, and excellent charge / discharge characteristics. In particular, when the negative electrode active material is a semiconductor such as silicon, doping with a high concentration of impurities improves the electron conductivity inside the electrode, smoothes the alloying of the ultrafine particle active material and lithium, and performs charge / discharge. The rate characteristics of the device are improved.
Furthermore, by using a lithium-containing transition metal oxide as a main constituent material of the positive electrode active material, the potential of the positive electrode is high, so that the voltage of the battery becomes high, and the high energy density is achieved because of its large capacity. .

[0031]

Embodiments of the present invention will be described below.

EXAMPLE 1 A silicon single crystal, which is a p-type semiconductor doped with 10 ⁴ silicon atoms at a ratio of 1 B atom, was used as a target, and 200 μW in vacuum, 10 μm electrolytic copper under conditions of 2 hours. Argon sputtering was performed on the foil to obtain a silicon layer of about 3 μm. SEM of this silicon layer
When the image was observed, the particle size of this silicon layer was 0.1 to
It was confirmed that the particles were ultrafine particles having a size of 0.01 μm.

This ultrafine silicon negative electrode was cut into a size of 5 × 5 mm, and the weight was measured to obtain a negative electrode. Then, 1
A spot welding was performed on a nickel plate of 0 × 10 mm, and a wire was attached as a test electrode. The following operations were performed in dry air, and all the materials were used after sufficiently drying in advance. Two pieces of metal lithium having an appropriate size were pressed on a nickel plate to prepare two pieces, which were used as a counter electrode and a potential reference electrode. In a beaker, a mixed solvent of ethylene carbonate and diethyl carbonate in a volume ratio of 1: 1 (C ₂ F ₅ SO
_{2) 2} NLi using an electrolyte prepared by dissolving 1mol / liter, three electrodes produced above, i.e. the test electrode, a counter electrode,
The potential reference electrode was immersed in the electrolytic solution to form a three-terminal cell. This single-pole performance test cell is referred to as (a).

Comparative Example 1 A silicon single crystal was cut out into a size of 0.3 × 5 × 5 mm as silicon other than ultrafine particles, and the weight was measured. A single-electrode performance test cell was prepared in the same manner as in Example 1 except that this silicon single crystal was sandwiched between nickel meshes and used as a negative electrode, and a similar capacity test was performed. This single-pole performance test cell is referred to as (b).

A charge / discharge test was performed using these unipolar performance test cells. A 1 mA current was passed through the cell, and a capacity test was performed for a potential of the test electrode with respect to the potential reference electrode in the range of 0.00 to 2.00 V. Table 1 shows the capacity test results of the monopolar performance test cell manufactured in this manner.

[0036]

[Table 1]

With respect to the unipolar performance test cell (a) using ultrafine silicon particles, insertion and extraction of lithium was confirmed, but in cell (b), almost no insertion and extraction of lithium was observed, and lithium was observed. . Further, when a high-rate discharge at 10 mA was performed using this single-electrode performance evaluation cell (a), about 85% of the discharge capacity at 1 mA was obtained. When low-temperature discharge at -20 ° C and 1 mA was performed, about 70% of the discharge capacity at 20 ° C was obtained.

As is evident from the results, the negative electrode using the ultrafine silicon particles of the present invention has excellent charge / discharge cycle characteristics, high capacity, and is capable of high-rate discharge and low-temperature discharge. . The reason for this is not clear, but is considered as follows. In other words, since silicon with large particles has a regular crystal arrangement, the field where lithium can exist is determined, and the reaction on the silicon surface proceeds instantaneously, but the alloying reaction to the inside is rate-limiting. It is considered that when rapid charging is performed, lithium is deposited. In comparison, ultrafine silicon particles have a large surface area to react due to their fine particles, and reactions such as lithium adsorption and alloying proceed simultaneously, and good characteristics can be obtained even during rapid charging, high-rate discharge, and low-temperature discharge. Can be considered. Further, even if the volume changes during the insertion and extraction of lithium, it is considered that the crystal is hardly disintegrated due to the ultrafine particles, and the cycle characteristics are improved.

Example 2 Using the negative electrode used in Example 1, a coin-type non-aqueous electrolyte battery was prototyped as follows.
The negative electrode used in Example 1 was punched into a circle having a diameter of 16 mm, and dried at 200 ° C. under reduced pressure for 15 hours to obtain a negative electrode 2. The negative electrode 2 was used by attaching the surface of a negative electrode current collector 7, which is a 10 μm electrolytic copper foil used as a substrate during argon sputtering, to a negative electrode can 5. The positive electrode 1 uses Li as a positive electrode active material.
CoO ₂ and acetylene black and polytetrafluoroethylene powder were mixed at a weight ratio of 85: 10: 5, and toluene was added and kneaded sufficiently. This was formed into a 0.8 mm thick sheet by a roller press. Next, this was punched out into a circle having a diameter of 16 mm and dried under reduced pressure at 200 ° C. for 15 hours to obtain a positive electrode 1. The positive electrode 1 was used by being pressed against a positive electrode can 4 provided with a positive electrode current collector 6. An electrolytic solution in which (C ₂ F ₅ SO ₂ ) ₂ NLi was dissolved at 1 mol / liter in a mixed solvent of ethylene carbonate and diethyl carbonate at a volume ratio of 1: 1 was used, and a microporous polypropylene membrane was used as the separator 3. A coin-type lithium battery having a diameter of 20 mm and a thickness of 1.6 mm was manufactured using the above-mentioned positive electrode, negative electrode, electrolyte and separator. This battery is referred to as battery (A1).

Example 3 As a solute of an electrolytic solution, (C ₂
A battery was fabricated in the same manner as in the present invention except that LiBF ₄ was used instead of F ₅ SO ₂ ) ₂ NLi. The obtained battery is referred to as a battery (A2).

The battery of the present invention (A
A charge / discharge cycle test was performed using 1) and (A2).
The test conditions were a charging current of 3 mA, a charging end voltage of 4.1 V,
The discharge current was 3 mA, and the discharge end voltage was 3.0 V. Table 2 shows the results of the charge / discharge test of these batteries.

[0042]

[Table 2]

As can be seen from Table 2, the battery (A1) using the salt containing carbon has better charge / discharge characteristics than the battery (A2) using LiBF ₄ as the solute of the electrolytic solution.
The decrease after cycling was small. The reason for this is not clear, but is considered as follows. That is, the third embodiment
When LiBF ₄ is used for the electrolyte as described above, it is considered that although the ion conductivity of the electrolyte itself is excellent, impurities such as hydrogen fluoride are present in the electrolyte due to decomposition of the solute. When lithium is absorbed and released into ultrafine silicon using such an electrolytic solution, impurities generated from the solute react with the coating existing on the surface of the ultrafine silicon, and the surface coating has high electric resistance and high ion conductivity. It is conceivable that the film changes to a film having poor quality. Therefore, the electrode resistance increases each time charging / discharging is performed, lowering the charging / discharging efficiency,
Therefore, it is considered that this leads to cycle deterioration. On the other hand, salts containing carbon are hardly decomposed and hardly release hydrogen fluoride or the like even in the reaction with water.Therefore, when occlusion and release of lithium into ultrafine silicon particles, increase in electric resistance on the surface, It is conceivable that the decrease in ion conductivity is suppressed, the charge / discharge efficiency is improved, and the cycle characteristics are improved. In the above, silicon is used as the ultrafine particle active material, and (C ₂ F ₅ SO
₂₎ given for ₂ NLi, other elements or compounds similar effects as ultrafine active material, also was confirmed also salts containing other carbon as an electrolytic solution. The present invention is not limited to the starting materials, the production method, the positive electrode, the negative electrode, the electrolyte, the separator, the shape of the battery, and the like of the active material described in the above-described embodiment.

[0044]

Since the present invention is constructed as described above, it exhibits excellent charge / discharge cycle characteristics at high voltage, high capacity, and high energy density, and has rapid charge characteristics, high rate discharge characteristics,
A non-aqueous electrolyte battery having excellent low-temperature discharge characteristics, high output, and high safety can be provided.

[Brief description of the drawings]

FIG. 1 is a sectional view of a coin-type nonaqueous electrolyte battery according to the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 positive electrode 2 negative electrode 3 separator 4 positive electrode can 5 negative electrode can 6 positive electrode current collector 7 negative electrode current collector 8 insulating packing

Claims (7)

[Claims] 1. A non-aqueous electrolyte battery, wherein the main constituent material of the negative electrode active material is ultrafine particles. 2. The method according to claim 1, wherein the ultrafine particles have a particle size of 0.1 to 0.01 μm.
2. The non-aqueous electrolyte battery according to claim 1, wherein the particle size is: 3. The non-aqueous electrolyte battery according to claim 1, wherein the ultrafine particles are silicon. 4. The non-aqueous electrolyte battery according to claim 1, wherein the main constituent solute of the non-aqueous electrolyte is a salt containing carbon. 5. A salt containing the carbon, the following general formula _{(1) (R1 SO 2)} (R2 SO 2) NLi ···· general formula (1) becomes possible according to claim 4, wherein Non-aqueous electrolyte battery. 6. R in the general formula (1) of the salt containing carbon
1, R2 is represented by C _n F _{2n + 1, n} is a number from 1 to 4, the non-aqueous electrolyte battery according to claim 5, wherein it is R1 = R2 or R1 ≠ R2. 7. A non-aqueous electrolyte battery, wherein the main constituent of the negative electrode active material is ultrafine silicon, and the main constituent of the positive electrode active material is a lithium-containing transition metal oxide.