JP2003223930A - Non-aqueous electrolytic cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a non-aqueous electrolytic cell which has high energy density and outstanding charging/discharging cycle characteristics. <P>SOLUTION: With respect to the non-aqueous electrolytic cell 1 which consists of a positive electrode 3 containing a positive-electrode active material that carries out electrochemical reaction with lithium ions reversibly, a negative electrode 4, and a non-aqueous electrolyte containing a non-aqueous solvent, the positive-electrode active material is lithium transition metal complex oxide expressed by a general formula of LiM<SB>z</SB>Mn<SB>2-z</SB>O<SB>4</SB>(M is one or more sorts of elements chosen from Cr, Fe, Co, Ni, Cu, and Zn, 0<z≤0.5), and the non-aqueous solvent contains cyclic carboxylate with a rate of 50 volume % or more. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a non-aqueous electrolyte battery.

[0002]

2. Description of the Related Art In recent years, hybrid vehicles (HEV), which emit less carbon dioxide than conventional gasoline vehicles, and carbon dioxide have been used as means for solving the problem of global warming caused by an increase in carbon dioxide concentration in the atmosphere. Attempts have been made to spread the use of electric vehicles (EVs) that do not emit
A battery having a high energy density is required as a battery for a V or EV power source. Further, due to the demand for further miniaturization of electronic devices such as portable wireless telephones, portable personal computers, and portable video cameras, high energy density is also required for these built-in power source batteries.

As a battery having a high energy density, a non-aqueous electrolyte battery comprising a positive electrode, a negative electrode and a non-aqueous electrolyte containing an organic solvent or a polymer solid electrolyte is known. In this non-aqueous electrolyte battery, a positive electrode containing a positive electrode active material that reversibly electrochemically reacts with lithium ions, a negative electrode containing a negative electrode active material capable of reversibly occluding and releasing lithium ions, and a lithium salt are included. A lithium ion secondary battery composed of an electrolyte that has a high energy density and excellent charge / discharge cycle characteristics has been widely put into practical use as a power source for portable devices and the like.

However, due to easiness of synthesis, LiC
In the case of a conventional lithium-ion secondary battery using oO ₂ as a positive electrode active material, the positive electrode potential at an open circuit is 4.3 V (4.2 V for the battery), so an energy density that is not always sufficient for the above requirements. Couldn't get

In order to solve such a problem, special table 20
No. 00-515672, LiNi _0.5 Mn having a positive electrode potential of 4.8 V (4.7 V in a battery) in an open circuit.
_1. Attempts to use ₅ O ₄ as a positive electrode active material have been proposed. The energy density is calculated, for example, by dividing the product of the discharge capacity and the average discharge voltage by the mass of the battery or the volume of the battery. it can.

However, in such a high voltage battery, when a mixed solution of cyclic carbonic acid ester and chain carbonic acid ester such as EC: DEC which has been conventionally used as an electrolytic solution of a lithium ion secondary battery is used, There is a problem that the discharge cycle characteristics are significantly deteriorated. This is considered to be because the electrolyte solution was oxidatively decomposed at the positive electrode during charging by LiNi _0.5 Mn _1.5 O ₄ having an extremely noble potential.

[0007]

The present invention was completed in view of the above circumstances and provides a non-aqueous electrolyte battery having a high energy density and excellent charge / discharge cycle characteristics. With the goal.

[0008]

As a means for achieving the above object, the invention of claim 1 is a positive electrode containing a positive electrode active material which reversibly electrochemically reacts with lithium ions, and a negative electrode. In a non-aqueous electrolyte battery comprising a non-aqueous electrolyte containing a non-aqueous solvent, the positive electrode active material has the general formula LiM _z.
Mn _{2-z O} 4 (M is, Cr, Fe, Co, Ni , C
u, one or more elements selected from Zn, 0 <z ≦ 0.
5) The lithium-transition metal composite oxide represented by 5), wherein the non-aqueous solvent contains cyclic carboxylic acid ester in a proportion of 50% by volume or more.

First, as a positive electrode active material, a general formula LiM _z Mn _2-z O having a high discharge potential based on Li / Li ^{+ is used.}
₄ (M is one or more elements selected from Cr, Fe, Co, Ni, Cu, Zn, 0 <z ≦ 0.5), the energy density It is possible to obtain a high-performance non-aqueous electrolyte battery.

Next, since the non-aqueous solvent contains the cyclic carboxylic acid ester in a proportion of 50% by volume or more, oxidative decomposition of the electrolytic solution at the positive electrode during charging is suppressed, so that excellent charge / discharge cycle characteristics are obtained. A non-aqueous electrolyte battery provided can be obtained. This is because the cyclic carboxylic acid ester has a high oxidative decomposition potential, so LiM _z Mn showing a very noble potential.
_It is considered that even when _{2-zO 4} is used as the positive electrode active material, it is difficult to undergo anodic oxidation.

When the proportion of the cyclic carboxylic acid ester in the non-aqueous solvent is less than 50% by volume, oxidative decomposition of the electrolytic solution components other than the cyclic carboxylic acid ester preferentially progresses in the positive electrode, resulting in charge / discharge cycle characteristics. It is not preferable because it decreases.

According to a second aspect of the present invention, in the nonaqueous electrolyte battery according to the first aspect, the cyclic carboxylic acid ester is γ-.
It is characterized by being butyrolactone.

Since the cyclic carboxylic acid ester is γ-butyrolactone which is a specific non-aqueous solvent, the charge / discharge cycle characteristics are remarkably improved. It is considered that this is because the oxidative decomposition potential of γ-butyrolactone is extremely high.

The invention of claim 3 is the non-aqueous electrolyte battery according to claim 1 or 2, wherein the non-aqueous electrolyte contains vinylene carbonate.

Since the non-aqueous electrolyte contains vinylene carbonate, the reductive decomposition of the cyclic carboxylic acid ester at the negative electrode is suppressed during charging, so that the charge / discharge cycle characteristics are improved.

It is known that γ-butyrolactone is decomposed by reacting with graphite on the negative electrode during charging, resulting in an increase in irreversible capacity and deterioration in charge / discharge efficiency (see “Battery Handbook-III” published by Maruzen). Edition ", p. 279). this is,
This is probably because the reductive decomposition potential of γ-butyrolactone was as low as 1.4 V on the basis of Li / Li ⁺ . In order to suppress the reductive decomposition of γ-butyrolactone, a compound having a reductive decomposition potential more noble than that of γ-butyrolactone is added, and a film formed on the negative electrode by the reaction between the compound and the negative electrode is chemically formed. It seems necessary to be stable. Vinylene carbonate has a reductive decomposition potential of 1.5 V on the Li / Li ⁺ basis, which is nobler than γ-butyrolactone. And vinylene carbonate is a cyclic carbonic acid ester having a carbon-carbon unsaturated bond, and in such a cyclic carbonic acid ester, ring-opening dimerization proceeds after polymerization at the unsaturated bond portion during reduction. Therefore, the film formed on the negative electrode becomes dense and strong, and it can be said that this film is chemically stable. Therefore, since the non-aqueous electrolyte contains vinylene carbonate, the reductive decomposition of vinylene carbonate on the negative electrode takes precedence over γ-butyrolactone, and γ-butyrolactone is formed by the film formed on the negative electrode as a result of this reaction. It is considered that the reaction between the anode and the negative electrode is suppressed. As described above, since the non-aqueous electrolyte contains vinylene carbonate, the reductive decomposition of the cyclic carboxylic acid ester at the negative electrode during charging is suppressed, so that the charge / discharge cycle characteristics are improved.

The addition amount of the vinylene carbonate is preferably 0.1% by weight or more and 2% by weight or less based on the total mass of the electrolytic solution including the vinylene carbonate.

When the amount of vinylene carbonate added is less than 0.1% by weight, a stable film is not sufficiently formed on the negative electrode, so that the reductive decomposition of γ-butyrolactone on the negative electrode is not suppressed and the charge-discharge cycle characteristics are improved. It is not preferable because it decreases. If it exceeds 2% by weight, excess vinylene carbonate is oxidatively decomposed at the positive electrode to generate gas, which causes the battery to swell and deteriorates the charge / discharge cycle characteristics, which is not preferable.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic cross-sectional view of a prismatic nonaqueous electrolyte battery 1 according to an embodiment of the present invention. This prismatic non-aqueous electrolyte battery 1 is configured by accommodating a positive electrode 3, an electrode group 2 in which a negative electrode 4 is wound with a separator 5 in between, and a non-aqueous electrolyte (not shown) in a battery case.

A battery lid 7 provided with a safety valve 8 is attached to the battery case 6 by laser welding, and the negative electrode terminal 9 is connected to the negative electrode 4 via a negative electrode lead 11.
The positive electrode 3 is electrically connected to the inner wall of the battery case 6 by the positive electrode lead 10.

In the present invention, as the positive electrode active material, a lithium transition metal composite oxide represented by the general formula LiM _z Mn ₂ -z O ₄ (0 <z ≦ 0.5) is used. M is
It is one or more elements selected from Cr, Fe, Co, Ni, Cu, and Zn, among which Co, Ni, and Cu are preferable, and Ni is particularly preferable.

The LiM _z Mn used in the present invention
_2-z O ₄ (M is Cr, Fe, Co, Ni, Cu, Z
one or more elements selected from n, 0 <z ≦ 0.5),
It can be synthesized by a solid-phase reaction method or a sol-gel method. When the solid-phase reaction method is used, a lithium compound such as lithium carbonate, a manganese compound such as manganese dioxide, and a transition metal compound such as nickel nitrate are mixed to obtain 600 to
The positive electrode active material can be synthesized by repeating the step of firing in the temperature range of 900 ° C. while performing the pressure treatment in this process. When using the sol-gel method, one or a mixture of inorganic salts, hydroxides and organic acid salts of lithium is used as a starting material for manganese, and the inorganic and organic acid salts of the selected metal are used. One of them or a mixture thereof is used as a starting material for the substituted metal species M. And
A positive electrode active material can be synthesized by performing a gelling step of adding ammonia water to an alcoholic solution or an aqueous solution of these starting materials to obtain a gel-like substance and a step of firing the obtained gel-like substance.

The lithium-transition metal composite oxide obtained as described above, a conductive agent, and a binder are mixed to prepare a positive electrode mixture, and this positive electrode mixture is composed of a metal foil as a positive electrode current collector. The positive electrode can be produced by applying it to the body.

The type of the conductive agent is not particularly limited, and it may be a metal or a nonmetal. As a metal conductive agent,
Examples thereof include materials composed of metal elements such as Cu and Ni. Examples of the non-metal conductive agent include carbon materials such as graphite, carbon black, acetylene black and Ketjen black.

The binder is not particularly limited in its kind as long as it is a material which is stable with respect to the solvent and electrolytic solution used at the time of manufacturing the electrode. Specifically, polyethylene, polypropylene,
Polyethylene terephthalate, aromatic polyamide, cellulose, styrene-butadiene rubber, isoprene rubber,
Butadiene rubber, ethylene-propylene rubber, styrene-butadiene-styrene block copolymer and hydrogenated product thereof, styrene-ethylene-butadiene-styrene block copolymer and hydrogenated product thereof, styrene-isoprene-styrene block copolymer and The hydrogenated product, syndiotactic 1,2-polybutadiene, ethylene-vinyl acetate copolymer, propylene-α-olefin (C2-12) copolymer, polyvinylidene fluoride, polytetrafluoroethylene, polytetrafluoro An ethylene-ethylene copolymer or the like can be used.

The positive electrode current collector includes, for example, Al, Ta, N
Examples thereof include b, Ti, Hf, Zr, Zn, W, Bi, and alloys containing these metals. Since these metals form a passivation film on the surface by anodic oxidation in the electrolytic solution, it is possible to effectively prevent the non-aqueous electrolyte from oxidatively decomposing in the liquid contact portion between the positive electrode current collector and the electrolytic solution. it can. As a result, the cycle characteristics of the non-aqueous secondary battery can be effectively improved. Of the above metals, A
1, Ti, Ta and alloys containing these metals can be preferably used. In particular, Al and its alloys have a low density, so that the mass of the positive electrode current collector can be reduced as compared with the case of using other metals. Therefore, the energy density of the battery can be improved, which is particularly preferable. The thickness of the current collector is preferably 7 μm or more and 20 μm or less.

When the positive electrode mixture obtained as described above is applied to the positive electrode current collector, it can be carried out by a known means. When the mixture is in the form of a slurry, it can be applied onto the current collector using, for example, a doctor blade. When the mixture is in the form of paste, it can be applied onto the current collector by, for example, roller coating. If a solvent is used, the electrode can be prepared by drying to remove the solvent.

As the negative electrode active material, lithium metal, lithium alloys capable of absorbing and releasing lithium, lithium alloys such as lithium-aluminum alloy, lithium-lead alloy and lithium-tin alloy, Li ₅ (Li ₃ N), etc. Lithium nitride, graphite, coke, pyrolytic carbons, carbons on glass,
Carbon materials such as fired bodies of organic polymer compounds, mesocarbon microbeads, carbon fibers and activated carbon, WO ₂ , MoO
Transition metal oxides such as ₂ , SnO ₂ , SnO, TiO ₂ , and NbO ₃ can be used. Only one kind of these negative electrode active materials may be selected and used, or two or more kinds thereof may be used in combination.

The material of the negative electrode current collector is preferably a metal such as copper, nickel or stainless steel, and among these, a copper foil is more preferable because it is easily processed into a thin film and is inexpensive.

The method for producing the negative electrode is not particularly limited, and the negative electrode can be produced by the same method as the above-mentioned method for producing the positive electrode.

Examples of the cyclic carboxylic acid ester used in the present invention include γ-butyrolactone, γ-valerolactone, α-acetyl-γ-butyrolactone, α-methyl-γ-butyrolactone, β-methyl-γ-butyrolactone, α-angelica lactone, α-methylene-γ-
Butyrolactone, γ-hexanolactone, γ-nonanolactone, γ-octanolactone, γ-methyl-γ-decanolactone and the like can be mentioned. Further, a part of hydrogen bonded to carbon of these cyclic carboxylic acid esters may be replaced with fluorine. Only one kind of these organic solvents may be selected and used, or two or more kinds thereof may be used in combination. Of these, γ-butyrolactone is preferable as the cyclic carboxylic acid ester.

As the solvent other than the cyclic carboxylic acid ester, for example, ethylene carbonate, propylene carbonate, dimethyl carbonate, ethylmethyl carbonate, diethyl carbonate, sulfolane, dimethyl sulfoxide, acetonitrile, dimethylformamide, dimethylacetamide, 1,2-dimethoxyethane, 1,
2-diethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, dioxolane, methyl acetate, trifluoropropylene carbonate, 3-methyl-1,3-dioxolane, methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, dipropyl carbonate , Methyl propyl carbonate, ethyl isopropyl carbonate and the like. Only one kind of these organic solvents may be selected and used, or two or more kinds thereof may be used in combination.

In the present invention, vinylene carbonate is preferably contained in the non-aqueous electrolyte. The addition amount of vinylene carbonate is preferably 0.1% by weight or more and 2% by weight or less with respect to the total mass of the electrolytic solution including vinylene carbonate.

As the electrolyte salt of the non-aqueous electrolytic solution, LiCl
Inorganic lithium salts such as O ₄ , LiAsF ₆ , LiPF ₆ , and LiBF ₄ , LiCF ₃ SO ₃ , and LiN (CF ₃ SO
_{2) 2, LiN (CF 3} CF 2 SO 2) 2, LiC
Examples thereof include a fluorine-containing organic lithium salt such as (CF ₃ SO ₂ ) ₃ . Only one kind of these solutes may be selected and used, or two or more kinds thereof may be used in combination. Of these, LiBF ₄ is preferable as the electrolyte salt.

As the electrolyte, a solid or gel electrolyte can be used in addition to the above-mentioned electrolyte solution. Examples of such an electrolyte include an inorganic solid electrolyte, polyethylene oxide, polypropylene oxide, or a derivative thereof.

Further, a compound having a surface active effect may be added to the non-aqueous electrolytic solution. Examples of the compound having a surface active effect include phosphoric acid ester and general formula R ₁ -OCO.
Is the are compounds described in _{O-R 2.} An example of a phosphoric acid ester is tris-n-butyl phosphate,
As an example of the compound represented by the general formula R ₁ -OCOO-R ₂ , R ₁ is a saturated or unsaturated hydrocarbon group having 4 to 12 carbon atoms, which may be linear or branched. .
Examples of R ₁ include isopropyl group and n-
Butyl group, isobutyl group, sec-butyl group, t-butyl group, 1-butenyl group, 2-butenyl group, 3-butenyl group, 2-methyl-2-propenyl group, 1-methylenepropyl group, 1-methyl 2 -Methylpropyl group, hexyl group, octyl group, nonyl group, decyl group, and other aliphatic hydrocarbon groups.

R ₂ is a saturated or unsaturated hydrocarbon group having 1 to 12 carbon atoms, which may be linear or branched. Examples of R ₂ include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group,
Isobutyl group, sec-butyl group, t-butyl group, 1-
Butenyl group, 2-butenyl group, 3-butenyl group, 2-methyl 2-propenyl group, 1-methylenepropyl group, 1-
Methyl 2-methylpropyl group, 1,2-dimethylvinyl group, 1-butynyl group, 2-butynyl group, 3-butynyl group, pentyl group, 1-methylbutyl group, 1-methyl2-
Examples thereof include aliphatic hydrocarbon groups such as methylpropyl group, hexyl group, octyl group, nonyl group and decyl group.

As the compound having a surface active effect, dinormal butyl carbonate (DNBC) is particularly preferable. This is because the wettability of the electrolytic solution can be improved while suppressing an increase in the viscosity of the electrolytic solution at low temperatures.

As the separator, an insulating microporous polyethylene film, a polypropylene microporous film, a polyethylene nonwoven fabric, a polypropylene nonwoven fabric, or the like impregnated with an electrolytic solution can be used. In addition, a polymer solid electrolyte or a gel electrolyte in which a polymer solid electrolyte contains an electrolytic solution can also be used. Further, an insulating microporous film and a polymer solid electrolyte may be used in combination. When the porous solid polymer electrolyte membrane is used as the solid polymer electrolyte, the electrolytic solution contained in the polymer may be different from the electrolytic solution contained in the pores.

The present invention will be described in detail below based on examples. The present invention is not limited to the following examples.

<Examples 1 to 3 and Comparative Examples 2 and 3
> 92 parts by weight of LiNi _0.5 Mn _1.5 O ₄ , 3 parts by weight of acetylene black as a conductive agent, and 5 parts by weight of polyvinylidene fluoride as a binder are mixed, and N-methyl-2-pyrrolidone is appropriately added. In addition, they were dispersed to prepare a slurry. This slurry was uniformly applied to both surfaces of a positive electrode current collector made of aluminum having a thickness of 20 μm, dried, and then compression-molded with a roll press to prepare a positive electrode 4.

90 parts by weight of graphite and 10 parts by weight of polyvinylidene fluoride were mixed, and N-methyl-2-pyrrolidone was appropriately added and dispersed to prepare a slurry. The slurry was uniformly applied to both surfaces of a copper negative electrode current collector having a thickness of 10 μm, dried, and then compression-molded by a roll press to prepare a negative electrode 3.

For the separator 5, a microporous polyethylene film having a thickness of 25 μm was used.

As the non-aqueous electrolyte, γ-butyrolactone (GBL) and ethylene carbonate (EC) are shown in Table 1.
The mixture was used in the ratio shown in. In addition, the numerical value of "non-aqueous solvent component (vol%)" in the table is GBL and E.
The volume% of each component in the mixture with C is shown. Also,
LiBF ₄ is used as the electrolyte salt, and its concentration is G
It was 1.5M for the mixture of BL and EC.

A prismatic nonaqueous electrolyte battery 1 having a width of 30 mm, a height of 48 mm and a thickness of 4.15 mm is manufactured by using the above-mentioned components.
Was produced.

<Examples 4 and 5> GB was used as the non-aqueous electrolyte.
Square non-aqueous electrolyte battery 1 was used in the same manner as in Example 1 except that L, EC, and ethyl methyl carbonate (EMC) or diethyl carbonate (DEC) were mixed in the proportions shown in Table 1. Was produced. In addition, the numerical value of "non-aqueous solvent component (vol%)" in the table is GBL and EC.
And% by volume of each component in the mixture with EMC or DEC.

<Examples 6 to 16> A prismatic non-aqueous electrolyte was prepared in the same manner as in Example 2 except that the compounds shown in Table 1 were used as the positive electrode active material and vinylene carbonate was added to the non-aqueous electrolyte. A battery 1 was produced. In the table, the "ingredient (wt%)", which is the mixing ratio of VC, is
The weight% of VC with respect to the total mass of the electrolytic solution including VC is shown.

<Comparative Examples 1 and 4> The compounds shown in Table 1 were used as the positive electrode active material, no cyclic carboxylic acid ester was contained in the non-aqueous electrolyte, and LiPF ₆ was used as the electrolyte salt. Except for the above, a prismatic nonaqueous electrolyte battery 1 was produced in the same manner as in Example 2.

In all batteries other than Comparative Example 4, 3 wt% of dinormal butyl carbonate (DNBC) was added as a surfactant to the total weight of the electrolytic solution.

<Measurement> For the batteries of Examples 1 to 16 and Comparative Examples 1 to 3, 600 m at 25 ° C.
Charged up to 4.8V with current of A, and 3 with constant voltage of 4.8V
After charging for a period of time, discharging to 3.5 V at a current of 600 mA was set as one cycle, and a 300-cycle charge / discharge test was performed. The ratio (%) of the discharge capacity at the 300th cycle to the discharge capacity at the first cycle of these batteries is summarized in Table 1 as the capacity retention rate. The discharge capacity at the first cycle is shown in Table 1 as "discharge capacity", and the average discharge voltage at this time is shown in Table 1 as "average discharge voltage".
Here, the average discharge voltage was the voltage at the midpoint of the discharge time.

Next, only the battery of Comparative Example 4 was subjected to a charge / discharge test under the same conditions as the above test except that the charging voltage was 4.2V and the discharge end voltage was 3.0V.

[0052]

[Table 1]

<Results> LiMn ₂ O ₄ was used as the positive electrode active material.
The average discharge voltage was 3.8 V in the battery of Comparative Example 4 using, while LiM _z Mn _2-z was used as the positive electrode active material.
The batteries of Examples 1 to 11 using O ₄ had a remarkably high average discharge voltage of 4.7V. In Examples 12 to 16 in which the Ni content in the positive electrode active material was changed, N
As the i content increased, the discharge capacity increased from 595 to 605 mAh and the average discharge voltage increased from 3.9 to 4.7V. From the above, L as the positive electrode active material
iM _{z Mn} 2-z O ₄ was found that it is possible to obtain a nonaqueous electrolyte battery having a high energy density by using a.

In Comparative Examples 1 to 3 in which the GBL concentration in the electrolyte is less than 50% by volume, the capacity retention rate is 60% or less, whereas in Examples 1 to 16 in which the GBL concentration in the electrolyte is 50% by volume or more. The capacity retention rate was remarkably high at 75% or more. This is due to the extremely high oxidative decomposition potential of GBL.
It is considered that the oxidative decomposition reaction of the electrolyte on the positive electrode having a very noble potential of 4.7 V was suppressed due to the inclusion of the above in the electrolyte. In Comparative Examples 2 and 3 in which the GBL content was less than 50% by volume, the capacity retention rate was low.
It is considered that the oxidative decomposition of EC proceeded preferentially on the positive electrode because the L concentration was low. Therefore, the proportion of GBL in the electrolyte is preferably 50% by volume or more.

In Examples 6 to 9 to which VC was added,
While the capacity retention rate was 81 to 85%, in Example 2 in which VC was not added, the capacity retention rate was 80%.
This is because VC reacts preferentially over GBL on the negative electrode to form a dense and stable film, resulting in G on the negative electrode.
It is considered that the reductive decomposition reaction of BL is suppressed. Therefore, the inclusion of VC in the electrolyte makes it possible to obtain a non-aqueous electrolyte battery having excellent charge / discharge cycle characteristics.

The effect of the substituted metal species will be examined by comparing Examples 7, 10 and 11. Both Co (Example 10) and Cu (Example 11) had a capacity retention rate of 80%, but the discharge capacity was 59 for Cu.
Co was 598 mAh, which was larger than that of 0 mAh. Therefore, when Co and Cu are compared, a non-aqueous electrolyte battery having a higher energy density can be obtained by using Co as the substitution metal species. On the other hand, N
In i (Example 7), the discharge capacity was 605 mAh and the capacity retention rate was 85%, both of which were superior to Co and Cu. Therefore, by using Ni as the substitution metal species,
A non-aqueous electrolyte battery having a high energy density and excellent charge / discharge cycle characteristics can be obtained. From the above, it was found that Co, Cu, and Ni are preferable as the substitutional metal species, and Ni is particularly preferable.

(Summary) From the above, a positive electrode containing a positive electrode active material that reversibly electrochemically reacts with lithium ions,
In a non-aqueous electrolyte battery including a negative electrode and a non-aqueous electrolyte containing a non-aqueous solvent, the positive electrode active material has a general formula of LiM _z Mn.
_2-z O ₄ (M is Cr, Fe, Co, Ni, Cu, Z
It is a lithium-transition metal composite oxide represented by one or more elements selected from n and 0 <z ≦ 0.5), and the non-aqueous solvent contains a cyclic carboxylic acid ester in a proportion of 50% by volume or more. It was found that a non-aqueous electrolyte battery having a high energy density and excellent charge / discharge cycle characteristics can be obtained.

<Other Embodiments> The present invention is not limited to the embodiments described above and illustrated in the drawings. For example, the following embodiments are also included in the technical scope of the present invention. In addition to the above, various modifications can be made without departing from the scope of the invention.

In the above-mentioned embodiment, the prismatic non-aqueous electrolyte battery 1 is described, but the battery structure is not particularly limited, and it is needless to say that it may be a cylindrical, bag-shaped, lithium polymer battery or the like.

[0060]

According to the non-aqueous electrolyte battery of the present invention, a non-aqueous electrolyte battery having a high energy density and excellent charge / discharge cycle characteristics can be obtained.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a prismatic nonaqueous electrolyte battery according to an embodiment of the present invention.

[Explanation of symbols]

1. Square non-aqueous electrolyte battery 2 ... Electrode group 3 ... Positive electrode 4 ... Negative electrode 5 ... Separator 6 ... Battery case 7 ... Battery lid 8 ... Safety valve 9 ... Negative electrode terminal 10 ... Positive electrode lead 11 ... Negative electrode lead

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Claims (3)

[Claims] 1. A non-aqueous electrolyte battery comprising a positive electrode containing a positive electrode active material that reversibly electrochemically reacts with lithium ions, a negative electrode, and a non-aqueous electrolyte containing a non-aqueous solvent, wherein the positive electrode active material is formula _{LiM z Mn 2-z O 4} (M is
A lithium transition metal composite oxide represented by one or more elements selected from Cr, Fe, Co, Ni, Cu, and Zn, 0 <z ≦ 0.5), and the nonaqueous solvent is 50% by volume or more A non-aqueous electrolyte battery comprising a cyclic carboxylic acid ester in a proportion of. 2. The non-aqueous electrolyte battery according to claim 1, wherein the cyclic carboxylic acid ester is γ-butyrolactone. 3. The non-aqueous electrolyte battery according to claim 1, wherein the non-aqueous electrolyte contains vinylene carbonate.