JP2001283811A - Separator and nonaqueous electrolyte battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve ion conductivity of a nonaqueous electrolyte. SOLUTION: An inorganic compound with specific dielectric constant of not less than 12 is included. With this arrangement, degree of ion dissociation of a lithium compound that is an electrolyte salt included in a nonaqueous electrolyte existing in and around cavities is improved. Therefore, resistance of lithium ion in a separator against ionic conduction is reduced, or, ion conductivity is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a separator used for a battery, and more particularly, to a non-aqueous electrolyte battery using the separator.

[0002]

2. Description of the Related Art Conventionally, nickel-cadmium batteries and lead batteries have been used as secondary batteries for electronic equipment. 2. Description of the Related Art In recent years, as electronic devices have become smaller and more portable with advances in electronic technology, it has become necessary to increase the energy density of secondary batteries for electronic devices. However, in nickel-cadmium batteries and lead batteries, the discharge voltage is low, and the energy density cannot be sufficiently increased.

Under these circumstances, so-called non-aqueous electrolyte batteries have been actively researched and developed in recent years. The characteristics of this nonaqueous electrolyte battery include a high discharge voltage and a light weight.

[0004]

As the non-aqueous electrolyte battery, a lithium battery utilizing the dissolution and deposition of lithium and a lithium ion battery utilizing doping and undoping of lithium ions are known. However, in each of the batteries, the conductivity of lithium ions greatly affects battery performance.

Therefore, in order to realize a battery having a high capacity and excellent load characteristics, low-temperature characteristics, and cycle characteristics, it is important to increase the ion conductivity of lithium ions in a battery system of a non-aqueous electrolyte battery. Will be an issue.

Therefore, for example, in a non-aqueous electrolyte of a non-aqueous electrolyte battery, a carbonate-based or ether-based non-aqueous solvent which is chemically and electrochemically stable and has a high dielectric constant is used, and a conventional LiPF ₆ is used as an electrolyte salt. And LiBF ₄
The use of imide-based lithium salts having a higher degree of dissociation to increase the ion conductivity has been studied.

On the other hand, in the battery reaction, when lithium ions move between the positive electrode and the negative electrode, they must pass through the separator, but the separator generally has lower ionic conductivity than the electrolyte. It has been known.

As a method of reducing the resistance to ion conduction of the separator and improving the ion conductivity of lithium ions, it is conceivable to increase the porosity or to make the separator thinner.

[0009] However, the separator having improved ionic conductivity by these methods has problems in the function as a diaphragm between the positive electrode and the negative electrode, mechanical strength, thermal strength, and uniformity of the film thickness. Will happen. Therefore,
These methods are not satisfactory solutions.

The present invention has been proposed in view of such a conventional situation, and has as its object to provide a separator having high ion conductivity. It is another object of the present invention to provide a nonaqueous electrolyte battery excellent in all of the capacity, cycle life, load characteristics, and low-temperature characteristics.

[0011]

In order to achieve the above-mentioned object, a separator according to the present invention is characterized by containing an inorganic compound having a relative dielectric constant of 12 or more.

A nonaqueous electrolyte battery according to the present invention comprises a negative electrode and a positive electrode, a nonaqueous electrolyte, and a separator, wherein the separator contains an inorganic compound having a relative dielectric constant of 12 or more. Is what you do.

When a dielectric inorganic compound is added to the separator, the inorganic compound dissociates the electrolyte salt (lithium salt) in the nonaqueous electrolyte impregnated in the pores of the separator or present near the separator. Improve the degree.

As a result, the resistance of the separator to ionic conduction of lithium ions is reduced, and the ionic conductivity is greatly improved.

At this time, since it is not necessary to increase the porosity of the separator or to make it thinner, the function as a diaphragm between the positive electrode and the negative electrode, mechanical strength, thermal strength, and the like are sufficiently ensured. You.

Therefore, in the non-aqueous electrolyte battery using this separator, lithium ions move smoothly between the positive electrode and the negative electrode, the internal impedance is reduced, and excellent load characteristics and low-temperature characteristics are realized. . Also,
Improving the ion conductivity of lithium ions is also advantageous in terms of cycle characteristics, and this characteristic is also improved.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a separator and a non-aqueous electrolyte battery to which the present invention is applied will be described in detail with reference to the drawings.

In the following, the configuration and materials of the separator and the thin films constituting the non-aqueous electrolyte battery will be described. However, the present invention is not limited to the illustrated non-aqueous electrolyte battery, but may be any desired one. The configuration and material of each thin film may be selected according to the purpose and performance.

The separator to which the present invention is applied is used, for example, in a non-aqueous electrolyte battery, and has a role as a diaphragm for preventing the positive electrode active material layer and the negative electrode active material layer from coming into contact with each other and causing a short circuit. Has a function as an ion conductive membrane.

The separator is made of a polymer material containing olefin or vinylidene fluoride as a repeating unit, such as polyolefin or polyvinylidene fluoride. And usually, it is a porous film in which many fine holes are formed.

The separator of the present invention contains an inorganic compound having a relative dielectric constant of 12 or more.

Inorganic compounds having a relative dielectric constant of 12 or more include those having ferroelectricity and those having paraelectricity, and any compound having a relative dielectric constant of 12 or more may be used. . Further, it is desirable that the relative dielectric constant is high. Specific examples of the ferroelectric inorganic compound include BaTiO ₃ ,
TiO _{2 and the} like. Examples of the paraelectric inorganic compound include BaO and the like.

Since these substances are chemically stable,
Insoluble or poorly soluble in non-aqueous electrolytes. In addition, it does not dissociate as ions. In addition, since these substances are electrochemically stable, they do not react with the positive electrode or the negative electrode.

By containing the above-mentioned inorganic compound, the dissociation degree of the lithium compound which is an electrolyte salt contained in the non-aqueous electrolyte existing in the pores of the separator and around the separator is increased. Therefore, the resistance of the separator to lithium ions is reduced, and the ion conductivity is high.

The above separator can be a single-layer film or a multilayer film.
What is necessary is just to disperse the inorganic compound whose relative dielectric constant is 12 or more in an arbitrary layer. Of course, in the case of a multilayer film, the inorganic compound having a relative dielectric constant of 12 or more can be dispersed in two or more layers or all the layers.

The separator is used, for example, as a separator of a non-aqueous electrolyte battery.

Hereinafter, a non-aqueous electrolyte battery manufactured using the separator to which the present invention is applied will be described.

As shown in FIG. 1, the non-aqueous electrolyte battery 1
A battery element in which a strip-shaped positive electrode 2 and a strip-shaped negative electrode 3 are wound in close contact with a separator 4 interposed therebetween is housed in a battery can 5.

The positive electrode 2 is manufactured by applying a positive electrode mixture containing a positive electrode active material and a binder on a current collector and drying the mixture. A metal foil such as an aluminum foil is used for the current collector.

As the positive electrode active material, a metal oxide, a metal sulfide, or a specific polymer can be used depending on the type of the intended battery.

For example, in the case of a lithium battery utilizing the dissolution and deposition of lithium, TiS ₂ , MoS ₂ , NbS
Metal sulfides or oxides not containing lithium, such as e ₂ and V ₂ O ₅ , and polymers such as polyacetylene and polypyrrole can also be used.

When a lithium ion battery utilizing doping / dedoping of lithium ions is used, Li _x MO
₂ (wherein M represents one or more transition metals, x varies depending on the charge / discharge state of the battery, and is usually 0.05 or more, 1.10
It is as follows. ) Can be used. As the transition metal M constituting the lithium composite oxide, Co, Ni, Mn, or the like is preferable. Specific examples of such a lithium composite oxide include L
iCoO ₂ , LiNiO ₂ , LiNi _y Co _1-y O ₂ (where 0 <y <1), LiMn ₂ O ₄ , LiMPO
₄ (where M represents one or more transition metals such as Fe).

The lithium composite oxide can generate a high voltage and is a positive electrode active material excellent in energy density. A plurality of these positive electrode active materials may be used in combination as the positive electrode active material. In addition, when the positive electrode active material is formed using the above-described positive electrode active material, a known conductive agent, a binder, and the like can be added.

The negative electrode 3 is manufactured by applying a negative electrode mixture containing a negative electrode active material and a binder on a current collector and drying the mixture. For the current collector, for example, a metal foil such as a copper foil is used.

As a negative electrode active material, for example, in the case of a lithium battery utilizing the dissolution and precipitation of lithium, metallic lithium, a lithium alloy capable of inserting and extracting lithium, and the like can be used.

In the case of a lithium ion battery utilizing doping / dedoping of lithium ions, a non-graphitizable carbon-based or graphite-based carbon material can be used. More specifically, carbon fibers such as graphites, mesocarbon microbeads, mesophase carbon fibers, pyrolytic carbons, cokes (pitch coke, needle coke,
Petroleum coke), vitreous carbons, organic polymer compound fired bodies (phenol resins, furan resins, etc. fired at an appropriate temperature and carbonized), and carbon materials such as activated carbon can be used. When forming a negative electrode from such a material, a known binder or the like can be added.

The non-aqueous electrolyte is prepared by dissolving an electrolyte salt in a non-aqueous solvent.

As the non-aqueous solvent, various non-aqueous solvents conventionally used for non-aqueous electrolytes can be used. For example, propylene carbonate, ethylene carbonate, dimethoxyethane, dimethyl carbonate, diethyl carbonate, γ-butyrolactone, tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxolan, 4-methyl-1,3-
Dioxolane, diethyl ether, sulfolane, methyl sulfolane, methyl sulfolane butyrate, acetonitrile,
Propion nitrile, methyl propionate and the like can be used. These non-aqueous solvents may be used alone or in combination of two or more.

As the electrolyte salt, LiPF ₆ , LiBF
₄ , LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiN
It is desirable to use at least one compound of (C ₂ F ₅ SO ₂ ) _{2 and the} like.

The above-described positive electrode 2 and negative electrode 3 are closely adhered to each other with a separator 4 interposed therebetween, and spirally wound to form a battery element.

Next, the insulating plate 6 is inserted into the bottom of the iron battery can 5 having nickel plating on the inside thereof, and the battery element is further housed.

To collect the current of the negative electrode 3, one end of a negative electrode lead 7 made of, for example, nickel is pressed against the negative electrode 3 and the other end is welded to the battery can 5. Thereby, the battery can 5
Is electrically connected to the negative electrode 3 and the nonaqueous electrolyte battery 1
External negative terminal.

In order to collect the current of the positive electrode 2, one end of a positive electrode lead 8 made of, for example, aluminum is attached to the positive electrode 2, and the other end is electrically connected to a battery lid 10 via a current interrupting thin plate 9. . The current interrupting thin plate 9 interrupts the current in accordance with the internal pressure of the battery. As a result, the battery lid 10 has conductivity with the positive electrode 2 and serves as an external positive electrode terminal of the nonaqueous electrolyte battery 1.

Next, a non-aqueous electrolyte is injected into the battery can 5. This non-aqueous electrolyte is prepared by dissolving an electrolyte salt in a non-aqueous solvent as described above.

Finally, the battery lid 5 is fixed by caulking the battery can 5 via the insulating sealing gasket 11 coated with asphalt, and the cylindrical nonaqueous electrolyte battery 1 is manufactured.

In the non-aqueous electrolyte battery 1 having the above structure, since the separator 4 contains a separator containing an inorganic compound having a relative dielectric constant of 12 or more, the movement of lithium ions between the positive electrode 2 and the negative electrode 3 is smooth. And the internal impedance is reduced.

Therefore, not only excellent load characteristics and low-temperature characteristics are realized, but also the capacity is increased and the cycle characteristics are greatly improved.

The shape of the non-aqueous electrolyte battery 1 is cylindrical here, but may be any shape such as a square, coin, button or the like, and the shape is not particularly limited. Absent. The dimensions are also arbitrary.

In the above description, an example in which a battery can is used using a liquid nonaqueous electrolyte has been described.
For example, when a gel electrolyte, a solid electrolyte, or the like is used as the nonaqueous electrolyte, a thin battery using a laminate film as an exterior material without using a battery can can be provided.

The gel electrolyte and the solid electrolyte basically comprise an electrolyte salt, a non-aqueous solvent dissolving the electrolyte salt, and a polymer matrix holding the non-aqueous solvent.

Here, as the non-aqueous solvent and the electrolyte salt, the same non-aqueous solvent and electrolyte salt as the liquid non-aqueous electrolyte can be used.

Examples of the polymer matrix include polyvinylidene fluoride, polyacrylonitrile, polyethylene oxide, polypropylene oxide, polymethacrylonitrile and the like. Depending on the type of use (gel, solid, etc.), these may be selected from these. used.

FIGS. 2 and 3 show an example of the configuration of a nonaqueous electrolyte battery 20 having a thin shape. The nonaqueous electrolyte battery 20 includes a positive electrode 21 having a positive electrode active material layer and a negative electrode active material. Battery element 2 formed by laminating negative electrode 22 having a layer with separator 23 interposed therebetween
4 is enclosed in the exterior film 25.

The current collector of the positive electrode 21 is connected to a positive electrode lead 26, and the current collector of the negative electrode 22 is connected to a negative electrode lead 27. The positive electrode lead 26 and the negative electrode lead 27 have a resin film 28 interposed in a sealing portion with the exterior film 25 to ensure insulation, and one end is drawn out.

A gel electrolyte layer is impregnated and solidified on each of the active material layers of the positive electrode 21 and the negative electrode 22, and the positive electrode 21 and the negative electrode 22 are separated from each other so that the gel electrolyte layers face each other. 23 are superimposed.

Therefore, the separator 23 is also partially impregnated with the gel electrolyte or the non-aqueous solvent in which the electrolyte salt contained therein is dissolved.

At this time, if a separator containing an inorganic compound having a relative dielectric constant of 12 or more is used as the separator 23, the internal impedance is reduced, and the load characteristics, low-temperature characteristics, The capacity and cycle characteristics are greatly improved.

[0058]

Next, specific examples to which the present invention is applied will be described based on experimental results.

Example 1 First, a negative electrode active material layer was prepared. First, 90 parts by weight of ground graphite powder and 10 parts by weight of polyvinylidene fluoride as a binder were mixed to prepare a negative electrode mixture.
Next, this negative electrode mixture was dispersed in N-methyl-2-pyrrolidone to form a slurry. Next, this was uniformly coated on one side of a strip-shaped copper foil having a thickness of 10 μm to be a negative electrode current collector and then dried. And the negative electrode active material layer was produced by compression-molding with a roll press machine.

Next, a positive electrode active material layer was prepared. First,
LiCO ₃ and CoCO ₃ were mixed at a ratio of 0.5 mol to 1.0 mol, and the mixture was calcined in air at 900 ° C. for 5 hours to produce LiCoO ₂ . Next, 91 parts by weight of this LiCoO ₂ , 6 parts by weight of graphite as a conductive agent, and 3 parts by weight of polyvinylidene fluoride as a binder were mixed to prepare a positive electrode mixture. Next, this was dispersed in N-methyl-2-pyrrolidone to form a slurry. Next, this was uniformly applied on one side of a strip-shaped aluminum foil having a thickness of 20 μm to be a positive electrode current collector, and then dried. And the positive electrode active material layer was produced by compression-molding with a roll press machine.

Next, a non-aqueous electrolyte was prepared. 15 parts by weight of ethylene carbonate (EC) and propylene carbonate (PC)
Was mixed with 50 parts by weight of diethyl carbonate and 20 parts by weight of LiPF ₆ as an electrolyte salt to prepare a non-aqueous electrolyte.

Next, a separator was prepared. First, 40 parts by weight of a polypropylene having a weight average molecular weight of 1,000,000 and 40 parts by weight of a high density polyethylene having a weight average molecular weight of 800,000 were mixed. Next, 10 parts by weight of BaTiO ₃ was added thereto. Next, apart from the above, the weight average molecular weight is 1,000,000
Was prepared by 10 parts by weight. Next, T
12μ thickness by 3 layer extrusion method by die extruder
A laminated film was prepared in which a mixed layer of polyethylene and polypropylene each having a thickness of 12 μm was formed on the principal surface. At this time, the temperature of the die in the T-die extruder was 230 ° C., and the temperature of the cooling roll was 80 ° C. Next, the laminated film is subjected to a heat treatment in the air. The conditions of the heat treatment are a temperature of 125 ° C. and a time of 40 hours.
Next, the laminated film was stretched using a roll stretching machine.
At this time, low-temperature stretching is first performed at 25 ° C. until the long stretch rate of the laminated film becomes 40%, and then 1%.
High temperature stretching was performed at 20 ° C. until the long stretch rate became 20%. Next, the length in the longitudinal direction of the laminated film stretched as described above was shrunk by 10% at 115 ° C.
Then, a separator which was a white porous film and was based on polyolefin was produced.

Finally, the positive electrode active material layer and the negative electrode active material layer were pressure-bonded with a separator interposed therebetween to form a wound body. Then, the wound body was accommodated in a battery can, and a non-aqueous electrolyte was injected to produce a non-aqueous electrolyte battery.

Example 2 When a separator was prepared, the weight average molecular weight was 100
31.1 parts by weight of 0000 polypropylene and 31.1 parts by weight of high density polyethylene having a weight average molecular weight of 800,000 were mixed. Then, for this, B
30 parts by weight of aTiO ₃ was added. Next, separately from the above, 7.8 parts by weight of polypropylene having a weight average molecular weight of 1,000,000 was prepared. Otherwise, a non-aqueous electrolyte battery was manufactured in the same manner as in Example 1.

Example 3 First, a positive electrode active material layer, a negative electrode active material layer, and a non-aqueous electrolyte were prepared in the same manner as in Example 1.

Next, a separator was prepared. First, 1
0 parts by weight of polyvinylidene fluoride, 20 parts by weight of ethanol, 20 parts by weight of isopropanol, 1 part by weight
10 parts by weight of butanol and 35 parts of tetrahydrofuran
Dissolved in the mixed solution with parts by weight. In addition, ethanol, isopropanol, 1-butanol, and tetrahydrofuran are volatile layer separation agents. Next, here BaTiO ₃
Was added to obtain a coating solution. Next, the coating solution was applied to a PET film subjected to a release treatment, and then dried at 50 ° C. Then, the film formed by the coating solution was peeled off from the PET film to produce a separator having polyvinylidene fluoride as a base material.

Finally, the positive electrode active material layer and the negative electrode active material layer were press-bonded with a separator interposed therebetween, to form a wound body. Then, the wound body was accommodated in a battery can, and a non-aqueous electrolyte was injected to produce a non-aqueous electrolyte battery.

Example 4 A non-aqueous electrolyte battery was manufactured in the same manner as in Example 1 except that TiO ₂ was added instead of BaTiO _{3 to} the separator.

Example 5 A non-aqueous electrolyte battery was manufactured in the same manner as in Example 1, except that BaO was added to the separator instead of BaTiO ₃ .

Example 6 First, a positive electrode active material layer, a negative electrode active material layer, and a separator were manufactured in the same manner as in Example 1.

Next, a gel electrolyte was prepared. First,
A plasticizer was prepared by mixing 12 parts by weight of ethylene carbonate (EC), 12 parts by weight of propylene carbonate (PC), and 6 parts by weight of LiPF ₆ as an electrolyte salt. Next, 10 parts by weight of block copolymer poly (vinylidene fluoride-co-hexafluoropropylene) having a molecular weight of 600,000 and 60 parts by weight of diethyl carbonate were mixed and dissolved in the plasticizer. Next, this was uniformly applied and impregnated on one side of the negative electrode active material layer and the positive electrode active material layer. Then, the mixture was allowed to stand at room temperature for 8 hours to vaporize and remove diethyl carbonate, thereby producing a gel electrolyte.

Finally, the positive electrode active material layer coated with the gel electrolyte and the negative electrode active material layer were pressed together with the surfaces coated with the gel electrolyte to form a battery element. Then, this battery element is housed in an exterior film,
A non-aqueous electrolyte battery having a size of 2.5 cm × 4.0 cm × 0.3 mm was produced.

Comparative Example 1 When a separator was prepared, the weight average molecular weight was 100
44.4 parts by weight of 0000 polypropylene and 44.4 parts by weight of high density polyethylene having a weight average molecular weight of 800,000 were mixed. Here, BaTi
O ₃ was not added. Next, separately from the above, 11.2 parts by weight of polypropylene having a weight average molecular weight of 1,000,000 was prepared. Otherwise, a non-aqueous electrolyte battery was manufactured in the same manner as in Example 1.

Comparative Example 2 When preparing a separator, polyvinylidene fluoride was used at 15 parts by weight, and BaTiO ₃ was not added.
Otherwise, a nonaqueous electrolyte battery was manufactured in the same manner as in Example 3.

Comparative Example 3 A non-aqueous electrolyte battery was manufactured in the same manner as in Example 1 except that Al ₂ O ₃ was added instead of BaTiO ₃ when manufacturing a separator.

Comparative Example 4 When a separator was prepared, the weight average molecular weight was 100
0000 of polypropylene and 45 parts by weight of high-density polyethylene having a weight average molecular weight of 800000
And 5 parts by weight. Here, BaTiO ₃ was not added. Next, separately from the above, 10 parts by weight of a polypropylene having a weight average molecular weight of 1,000,000 was prepared. Otherwise, a non-aqueous electrolyte battery was manufactured in the same manner as in Example 1.

The cycle life, load characteristics, and low temperature characteristics of the nonaqueous electrolyte batteries prepared in Examples 1 to 6 and Comparative Examples 1 to 4 were measured by the following methods.

<Cycle Life> A charge / discharge cycle test was performed 500 times in a 2 hour rate discharge (1/2 C) of the theoretical capacity, and the following evaluation was made. First, 23 for each battery
C. and constant-current constant-voltage charging was performed for 10 hours up to an upper limit of 4.2 V. Next, a 2-hour rate discharge (1 / 2C) was performed at a voltage of 3.2 throughout.
V. The discharge capacity is determined in this way, and the output at the time-rate discharge is calculated from the average voltage obtained from this.
10 for 5 hour rate discharge (1 / 5C) at the beginning of cycle
Calculated as 0 fraction.

<Load Characteristics> 1/3 hour rate discharge (3C) of the theoretical capacity was performed and evaluated as follows. First, constant-current constant-voltage charging at 23 ° C. was performed for each battery up to an upper limit of 4.2 V.
Performed for 0 hours. Next, 1/3 hour rate discharge (3C) was performed to a voltage of 3.2 V throughout. The discharge capacity was determined in this manner, and the output at each rate discharge was calculated from the average voltage obtained from this to 10% of the rate discharge for 5 hour rate discharge (１ ／ C).
Calculated as 0 fraction.

<Low-Temperature Characteristics> A two-hour rate discharge of theoretical capacity (1
/ 2C) at a low temperature and evaluated as follows. First,
The upper limit of constant current and constant voltage charging at 23 ° C. for each battery is 4.2.
V to 10 hours. Next, a 2-hour rate discharge (1/2
C) was performed at −20 ° C. until a voltage of 3.2 V throughout. Further, the output at the time rate discharge was calculated from the average voltage obtained as a percentage of 5 hour rate discharge (１ ／ C) at normal temperature (23 ° C.).

Examples 1 to 6 and Comparative Example 1
Table 1 shows the results of measuring the cycle life, load characteristics, and low-temperature characteristics of Comparative Example 4 to Comparative Example 4.

[0082]

[Table 1]

[0083] From Table 1, in the separator of polyolefin as a base material, BaTiO ₃ 10 parts by weight to 30 carried contains parts Example 1 and Example 2, Comparative Example 1 does not contain BaTiO ₃ It was found that the cycle life, the load characteristics, and the low-temperature characteristics were improved as compared with those of Example 1.

Further, in Example 3 in which 5 parts by weight of BaTiO ₃ was contained in the separator based on polyvinylidene fluoride, the cycle life was longer than that in Comparative Example 2 in which BaTiO ₃ was not contained. , Load characteristics, and low-temperature characteristics were found to be improved.

Also, in Example 4 in which 10 parts by weight of TiO ₂ was contained in the polyolefin-based separator, cycle life and load characteristics were higher than those in Comparative Example 1 in which TiO ₂ was not contained. And low-temperature characteristics were found to be improved.

Also, in Example 5 in which BaO was contained in a separator containing polyolefin as a base material in an amount of 10 parts by weight, compared to Comparative Example 1 in which BaO was not contained,
It was found that the cycle life, load characteristics, and low-temperature characteristics were improved.

Also, in Example 6 in which the separator based on polyolefin contained 10 parts by weight of BaTiO ₃ and the gel electrolyte was used as the non-aqueous electrolyte, BaTiO ₃ was not contained. Compared with Comparative Example 4, it was found that the cycle life, load characteristics, and low-temperature characteristics were improved.

In Comparative Example 3 in which a polyolefin-based separator contained 10 parts by weight of Al ₂ O ₃ having a relative dielectric constant of less than 12, BaTiO ₃ was 1%.
It was found that the cycle life, load characteristics, and low-temperature characteristics were lower than those in Example 1 in which 0 parts by weight were contained.

[0089]

As is clear from the above description, since the separator according to the present invention contains an inorganic compound having a relative dielectric constant of 12 or more, non-aqueous water existing in and around the pores is contained. The degree of dissociation of a lithium compound as an electrolyte salt contained in the electrolyte is improved. For this reason, the separator according to the present invention has high ion conductivity.

At this time, since the separator according to the present invention does not need to increase or reduce the porosity, the function as a diaphragm is sufficiently secured, and the separator has sufficient mechanical strength and thermal strength. It will be.

In a non-aqueous electrolyte battery using the above separator, lithium ions move smoothly between the positive electrode and the negative electrode, the internal impedance is reduced, and excellent load characteristics and low-temperature characteristics are realized. At the same time, higher capacity and improved cycle characteristics can be achieved.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing one embodiment of a nonaqueous electrolyte battery to which the present invention is applied.

FIG. 2 is a plan view showing another embodiment of the nonaqueous electrolyte battery to which the present invention is applied.

FIG. 3 is a sectional view of the nonaqueous electrolyte battery.

[Explanation of symbols]

0 Non-aqueous electrolyte battery, 2 positive electrode, 3 negative electrode, 4 separator, 5 battery can, 6 insulating plate, 7 negative electrode lead, 8 positive electrode lead, 9 thin plate for current interruption, 10 battery cover, 11
Insulation sealing gasket

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Futaro Hara 6-7-35 Kita-Shinagawa, Shinagawa-ku, Tokyo Sony Corporation F-term (reference) 5H021 CC02 EE04 EE10 EE31 HH00 5H029 AJ02 AJ03 AJ05 AJ06 AK03 AL07 AL08 AL12 AM00 AM03 AM04 AM05 AM07 AM16 BJ02 BJ03 BJ04 DJ04 EJ05 EJ12 HJ20

Claims (11)

[Claims] 1. A separator comprising an inorganic compound having a relative dielectric constant of 12 or more. 2. The separator according to claim 1, wherein the inorganic compound has ferroelectricity. 3. The method according to claim 1, wherein the inorganic compound is BaTiO ₃ and / or BaTiO _3.
Or separator according to claim 2, characterized in that the TiO _2. 4. The separator according to claim 1, wherein the inorganic compound has a paraelectric property. 5. The separator according to claim 1, wherein the separator is formed of a polymer material containing olefin and / or vinylidene fluoride as a repeating unit. 6. A non-aqueous electrolyte battery comprising a negative electrode and a positive electrode, a non-aqueous electrolyte, and a separator, wherein the separator contains an inorganic compound having a relative dielectric constant of 12 or more. 7. The non-aqueous electrolyte battery according to claim 6, wherein the inorganic compound has ferroelectricity. 8. The method according to claim 1, wherein the inorganic compound is BaTiO ₃ and / or BaTiO _3.
8. The non-aqueous electrolyte battery according to claim 7, wherein the battery is TiO ₂ . 9. The non-aqueous electrolyte battery according to claim 6, wherein said inorganic compound has paraelectricity. 10. The non-aqueous electrolyte according to claim 6, wherein the negative electrode contains a material capable of doping / dedoping lithium as an active material, and the positive electrode contains a lithium composite oxide as an active material. battery. 11. The non-aqueous electrolyte comprises LiPF ₆ , LiPF
BF ₄ , LiN (C ₂ F ₅ SO ₂ ) ₂ , LiN (CF ₃ S
The non-aqueous electrolyte battery according to claim 6, wherein at least one selected from O ₂ ) ₂ and LiCF ₃ SO ₃ is contained as an electrolyte salt.