JPH11297322A - Nonaqueous electrolyte secondary battery, and electrical device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lithium secondary battery superior in a battery capacity holding characteristic by controlling manganese elution from lithium-manganese oxide. SOLUTION: This nonaqueous electrolyte secondary battery includes a positive electrode 1, containing lithium-manganese oxide of spinel structure comprising lithium and manganese and containing a conductive agent, a negative electrode 2, a main solvent comprising ethylene carbonate or propylene carbonate, and an electrolyte comprising an ethylmethyl carbonate mixture containing disolved lithium tetrafluoroborate. An average particle size of the lithium-manganese oxide in the positive electrode is 10-30 μm, its specific surface area is 1-5 m<2> /g, the quantity of the oxide carried in the positive electrode 1 is 20-30 mg/cm<2> , an average particle size for the conductive agent is 30 μm or less, and a weight composition ratio of the conductive agent with respect to lithium-manganese oxide is 5-15 wt.%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-aqueous electrolyte secondary battery, and more particularly to a lithium secondary battery.

[0002]

2. Description of the Related Art Non-aqueous electrolyte secondary batteries represented by lithium secondary batteries have higher energy densities than lead-acid batteries and nickel-cadmium batteries, and have recently been used in video cameras, portable telephones, notebook computers, etc. It is used in portable electrical equipment.

The negative electrode active material of a lithium secondary battery includes lithium metal, a carbon material capable of storing lithium ions, and the like. The positive electrode active material includes a transition metal such as cobalt, nickel or manganese and lithium. Complex oxides are used.

[0004] In particular, oxides composed of manganese and lithium include LiMn ₂ O ₄ having a spinel structure (Japanese Patent Publication No.
8-34414) has been known for a long time. In order to improve the cycle life of this positive electrode active material, aluminum (Japanese Patent No. 2512241), iron (Japanese Patent Laid-Open No.
160758, JP-A-5-129019), cobalt (JP-A-4-160758, JP-A-5-129019), nickel (JP-A-4-1-1919)
No. 60758, Japanese Patent Application Laid-Open No. 5-129019),
Chromium (Japanese Patent Laid-Open No. 4-160758), Copper (Japanese Patent Laid-Open No. 5-129019), Zinc (Japanese Patent Laid-Open No. 5-1290)
No. 19), magnesium (Japanese Unexamined Patent Publication No. 5-129019).
Lithium-manganese oxide in which a part of manganese atoms is substituted with a dissimilar metal such as boron (Japanese Patent Application Laid-Open No. 5-129019), and lithium-manganese oxide in which a part of oxygen is substituted by fluorine (191st meeting) of the elec
trochemical society, Meeting abstract, 97-98
P.) Are known.

[0005]

With the spread of portable electrical equipment, there is a demand for a lithium secondary battery that can withstand long-time use and has excellent load characteristics.

[0006] On the other hand, development for reducing the material cost of batteries is also underway. Lithium cobaltate, which has been used in small consumer lithium secondary batteries, is replaced with inexpensive and resource-rich manganese. Lithium-manganese composite oxides are being commercialized (Journal of Power Sources, Vol. 54, No. 14).
3-145).

[0007] In particular, material cost is a practically important development issue for large lithium secondary batteries for electric vehicles and power storage.

A typical composite oxide of lithium and manganese is LiMn ₂ O ₄ having a spinel type crystal structure. When this is used as a positive electrode active material, trivalent manganese elutes into the electrolytic solution when used at a high temperature of about 55 ° C., and the capacity density of the positive electrode decreases (Journal of Electrochemical Societe).
y, vol 143, 2204-2211 (1996),
And the 191st meeting of the electrochemical so
ciety, Meeting abstract, p. 108).

[0009] The problem of manganese elution is found in devices in which the battery is easily exposed to a high-temperature environment, such as personal computers and electric vehicles. An object of the present invention is to provide a lithium secondary battery having excellent battery capacity retention characteristics by suppressing manganese elution from a lithium-manganese oxide.

[0010]

Means for Solving the Problems As a result of the present inventors working on a technical problem for preventing manganese elution, a series of spinel-type lithium-manganese oxides having a defined chemical composition, crystal structure, etc. By optimizing the composition of the positive electrode conductive agent by weight and the composition of the electrolytic solution, it was found that the amount of manganese eluted was significantly suppressed. That is, lithium-
The combination of a positive electrode containing manganese oxide and a conductive agent, a main solvent consisting of ethylene carbonate or propylene carbonate, and an electrolytic solution in which lithium tetrafluoroborate is dissolved in a mixed solvent of ethyl methyl carbonate makes the positive electrode thermally stable. The manganese elution reaction to the electrolytic solution was suppressed.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below. Book
Spinel-type crystal structure capable of suppressing manganese elution reaction by the invention
The conditions for lithium-manganese oxides are
The molar ratio of lithium to be stoichiometric is greater than 0.5
And preferably have a high value of 0.54 to 0.61
is there. When these oxides are represented by a chemical composition formula,
Formula Li _{1 + X}Mn_2-XO_FourBecomes However, X = 0.05-
0.14.

It is considered that the reason why manganese elution was suppressed by this composition was that the spinel-type crystal structure shrunk with an increase in the lithium content and the ionic bonding force increased.

The a-axis lattice constant of LiMn ₂ O ₄ having a stoichiometric composition (0.824 nm, Solid State Ionics, vol. 66,
135-142 (1993)), the lithium-manganese oxide has an a-axis lattice constant of 0.821.
It decreased to 0-0.8235 nm, the ionic bonding force of the present invention became strong, and the crystal shrank.

However, if the molar ratio of lithium to manganese is too large, it contributes to charging and discharging.
There is a disadvantage that manganese ions are reduced. When the molar ratio of lithium to manganese is expressed as Li / Mn ratio, it is desirable to limit the upper limit of the Li / Mn ratio in the present invention to 0.61.

On the other hand, if the average particle size of the lithium-manganese oxide is too large, there is a disadvantage that the electrode surface becomes rough. However, when the average particle size is reduced, the specific surface area of the lithium-manganese oxide powder is increased, and the reaction area between the oxide and the electrolyte is increased. As a result, the elution amount of manganese is increased. The average particle size and specific surface area of the lithium-manganese oxide are 10 to 30 μm and 1 to 5 m ² / g, respectively.
In this case, the amount of manganese eluted could be reduced.

The electrolytic solution of the present invention is a solution obtained by adding lithium tetrafluoroborate as an electrolyte to a mixed solution of a main solvent comprising ethylene carbonate or propylene carbonate and ethyl methyl carbonate. The effect of preventing the elution of manganese from the oxide to the electrolyte was confirmed.

Since the operating potential range of the positive electrode of the present invention is 3 to 4.3 V based on the Li metal reference electrode, the main solvent (ethylene carbonate, propylene carbonate) used in the electrolytic solution of the present invention is electrochemically oxidized. However, it is not considered that manganese ions in the positive electrode are eluted into the electrolytic solution.

Further, ethyl methyl carbonate in the second solvent is to promote the dissociation of lithium tetrafluoroborate (LiBF _4), BF ₄ ~ anion forms specific adsorption layer on the surface of the positive electrode, the BF ₄ ~ anion It is considered that the layer functions as a protective film for elution of manganese. Further, when lithium tetrafluoroborate is used for the electrolyte, the electrolyte of the present invention not only has a high electric conductivity of 5 to 10 mS / cm, but also has a characteristic that the electrolyte is hardly oxidized and decomposed on the positive electrode. .

In the present invention, the composition of the electrolytic solution having the effect of suppressing the elution of manganese is such that the volume ratio of the main solvent consisting of ethylene carbonate or propylene carbonate to ethyl methyl carbonate is 1: 0.3 to 1: 0.7. Was in the range.

The conductive agent used for the positive electrode is necessary to supplement the conductivity inside the positive electrode mixture because the lithium-manganese oxide has a high electric resistance. Further, in order to increase the discharge capacity density per unit volume of the positive electrode mixture, it is necessary to reduce the weight composition ratio to the lithium-manganese oxide as much as possible.

For this purpose, the particle size of the conductive agent is set to lithium-
It is necessary to make the conductive material smaller than the manganese oxide, uniformly disperse the conductive agent on the surface of the lithium-manganese oxide, and secure the electron conductivity between the lithium-manganese oxide particles with a small amount of the conductive agent. Examples of the carbon powder that can be used for the conductive agent include natural graphite, artificial graphite, carbon fiber, vapor grown carbon fiber, and pitch-based carbonaceous material.

As much as possible, the volume of the lithium-manganese oxide applied to the aluminum foil current collector is relatively reduced as the volume of the current collector is reduced.
Manganese oxide increases. That is, the energy density of the battery increases.

However, when the weight of the lithium-manganese oxide is too large, there is a problem that the lithium ion diffusion rate in the positive electrode mixture is reduced and the charge / discharge reaction of the positive electrode is hindered.

According to the present invention, 1 cm on one side of the positive electrode current collector
^The amount of lithium-manganese oxide carried per ² is 20 to
When it is in the range of 30 mg / cm ² , manganese elution can be suppressed while maintaining a high battery energy density.

If the weight of the conductive agent is sufficient to be 5 to 15% with respect to the lithium-manganese oxide and the average particle size of the conductive agent is 30 μm or less, the filling of the lithium-manganese oxide in the positive electrode is sufficient. It was found that by increasing the amount, the elution of manganese ions from the oxide could be prevented.

The manganese ions eluted from the lithium-manganese oxide include those dissolved in the electrolytic solution and those reduced and precipitated on the negative electrode surface after the elution. In particular, elution of manganese ions from the positive electrode reduces trivalent manganese ions that are oxidized and reduced by charging and discharging the positive electrode, resulting in a reduction in battery capacity. Manganese deposited on the negative electrode becomes a substance inhibiting the reaction of inserting and extracting lithium ions to and from the negative electrode, which causes a reduction in battery capacity.

According to the present invention, the amount of manganese eluted from the positive electrode can be reduced to 5% or less of the total amount of manganese remaining on the positive electrode. As a result, the rate of decrease in battery capacity due to manganese elution is reduced, and battery life can be extended.

By combining the lithium-manganese oxide, the conductive agent and the electrolytic solution of the present invention, elution of manganese ions from the positive electrode can be prevented and a decrease in capacity of the nonaqueous electrolyte secondary battery can be reduced. .

[0029]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail based on embodiments.

Example 1 The lithium-manganese oxide used in this example was prepared by mixing a mixture of electrolytic MnO ₂ and Li ₂ CO ₃ or LiNO ₃ by heat treatment at 900 ° C. in the air. -Manganese oxide was synthesized.

The synthesized oxide powder has an average particle size of 20 μm.
m, specific surface area measured by nitrogen adsorption method is 1 m ² /
g, five types of lithium-manganese oxides having different molar ratios of lithium to manganese. The Li / Mn ratio of the lithium-manganese oxide of this example was 0.54, 0.5.
6, 0.58, 0.61 and 0.63. These oxides are denoted as M1, M2, M3, M4, M5.

Using CuKα as an X-ray source, the X-ray diffraction pattern of each powder was measured. In any of the powders, a diffraction peak typical of a spinel crystal appeared at around 17, 36, 38, 44, and 48 at a diffraction angle 2θ value.
It was confirmed that the above five types of oxides had a spinel crystal structure.

The a-axis lattice constants of the oxides M1 to M5 are 0.8238, 0.8233, and 0.822, respectively.
5, 0.8215 and 0.8210 nm.

The positive electrode was manufactured according to the procedure described below. A positive electrode slurry was prepared by adding the oxide M1, natural graphite, and a 1-methyl-2-pyrrolidone solution of polyvinylidene fluoride and kneading the mixture. The mixing ratio of lithium-manganese oxide, natural graphite, and polyvinylidene fluoride is 90:
6: 4.

This slurry was applied to the surface of a positive electrode current collector made of an aluminum foil having a thickness of 20 μm by a doctor blade method. The dimensions of the positive electrode application surface are 54 mm wide x
The length is 47 mm. The coating weight of the oxide on one side of the current collector was 20 ± 1 mg / cm ² . This is 10
It dried at 0 degreeC for 2 hours, and produced the positive electrode.

Also, four kinds of positive electrodes were prepared in the same manner as described above using the oxides M2, M3, M4, and M5.

The weight of the oxide contained in the five kinds of positive electrodes of this example was 10.0 ± 0.2 g in all cases. This measured value was used for calculation of the manganese elution rate described later.

Next, the negative electrode was produced by the following method. Natural graphite powder with an average particle size of 5 μm and polyvinylidene fluoride
The mixture was mixed at a weight ratio of 9: 1, and 1-methyl-2 was used as an organic solvent.
-Pyrrolidone was added and kneaded well to prepare a negative electrode slurry. This slurry is made by the doctor blade method.
It was applied to the surface of a negative electrode current collector made of a copper foil having a thickness of 18 μm. The dimensions of the negative electrode application surface are 56 mm in width × 51 mm in length. This was dried at 100 ° C. for 2 hours to produce a negative electrode.

Combining a positive electrode using the oxide M1, a negative electrode, and a polyethylene separator having a thickness of 25 μm,
A cylindrical battery 1 having a height of 65 mm and a diameter of 18 mm was assembled. This battery is designated as B1.

FIG. 1 shows a sectional view of the manufactured cylindrical battery. The positive electrode 1 and the negative electrode 2 are housed in a battery can 4 in a state of being spirally wound via a polyethylene separator 3. The polyethylene separator 3 contains a non-aqueous electrolyte inside the pores thereof, and allows lithium ions to move.

The composition of the electrolyte used in this example is a non-aqueous electrolyte obtained by dissolving 1 mol / liter of lithium tetrafluoroborate (LiBF ₄ ) in a mixed solvent of ethylene carbonate and ethyl methyl carbonate. . The volume ratio between ethylene carbonate and ethyl methyl carbonate was 1: 1. This electrolyte is referred to as S1.

The positive electrode 1 is connected to a positive electrode lead 5 and is electrically connected from the bottom surface of the battery cover 6 to a positive electrode external terminal 7.
Further, the negative electrode 2 is connected to the negative electrode lead 7,
Are welded to the bottom surface of the battery can 4. With such a configuration, the electrochemical energy of the battery can be taken out from the battery lid 6 and the battery can 4 or recharged.

Similarly, a cylindrical battery having the same shape was manufactured by combining a positive electrode containing the oxides M2, M3, M4, and M5, a negative electrode, and a polyethylene separator having a thickness of 25 μm. These batteries are referred to as B2, B3, B4,
Notated as B5. The number of batteries is 10 for each positive electrode active material.
And a total of 50. The electrolyte used was S1,
The injection volume is about 4 ml.

The rated capacities of the batteries B1 to B5 produced in this example were 0.90 A, calculated from the filling amount of the positive electrode active material.
h. These batteries have a charging current of 0.45 A,
After charging for 5 hours at a constant current-constant voltage of 4.2 V, the battery was discharged to 2.8 V at a discharge current of 0.45 A. This charge / discharge cycle was performed three times, and the average value of the discharge capacity was determined. The initial capacity is shown in Table 1 collectively. Batteries B1 of the present invention
The initial capacity of B5 was equal to the rated capacity and was 0.90 Ah.

[0045]

[Table 1]

Example 2 Oxide powder M3 of Example 1
Combination of a positive electrode, a negative electrode and a 25 μm-thick polyethylene separator using
mm cylindrical battery was assembled. The number of manufactured batteries was set to 20. In 10 of these batteries, the volume ratio of ethylene carbonate to ethyl methyl carbonate was 1:
About 4 ml of 0.3 electrolyte was injected. The electrolyte used here is referred to as S6, and the battery is referred to as B6.

Further, the remaining 10 batteries had a volume ratio of ethylene carbonate to ethyl methyl carbonate of 1:
Approximately 4 ml of the electrolytic solution adjusted to 0.7 was injected. The type and concentration of the electrolyte are the same as those of the electrolyte S6. The electrolyte used here is referred to as S7, and the battery is referred to as B7.

The rated capacity of the two types of batteries manufactured in this example is 0.90 Ah based on the filling amount of the positive electrode active material. As a result of measuring the initial capacities of these batteries under the same conditions as in Example 1, the initial capacities of the batteries B6 and B7 were equal to the rated capacities,
It was 0.90 Ah.

Comparative Example 1 Positive electrode M produced in Example 1
3, a negative electrode and a 25 μm-thick polyethylene separator were combined to assemble a cylindrical battery having a height of 65 mm and a diameter of 18 mm. The number of manufactured batteries was set to 20. In 10 of these batteries, ethylene carbonate and ethyl methyl carbonate in a volume ratio of 1: 0.1
About 4 ml of an electrolytic solution in which BF ₄ was dissolved was injected. The electrolyte used here is referred to as S8, and the battery is referred to as B8.

Further, the volume ratio of 1: 0.9 to ten batteries was
About 4 ml of an electrolyte obtained by dissolving LiBF ₄ in ethylene carbonate and ethyl methyl carbonate was injected. The type and concentration of the electrolyte are the same as those of the electrolyte S6. The electrolyte used here is referred to as S9, and the battery is referred to as B9.

The rated capacity of the two types of batteries manufactured in this comparative example is 0.90 Ah based on the filling amount of the positive electrode active material. The initial capacities of these batteries were measured in the same manner as in Example 1. The initial capacity of the battery B9 of this comparative example was 0.1% according to the rated capacity.
Although the battery capacity was 90 Ah, the initial capacity of the battery B8 was lower than the rated capacity and was 0.75 Ah. The reason for this capacity decrease is an increase in the resistance of the electrolyte due to the decrease in ethyl methyl carbonate.

Comparative Example 2 The lithium-manganese oxide used in this comparative example was prepared by subjecting a mixture of electrolytic MnO ₂ and Li ₂ CO ₃ or LiNO ₃ to heat treatment at 900 ° C. in the air to obtain a molar ratio of lithium to manganese. Different lithium-manganese oxides were synthesized.

The synthesized oxide powder has an average particle size of 20 μm.
m, specific surface area measured by nitrogen adsorption method is 1 m ² /
g and Li / Mn ratio were 0.51. This oxide is
Notated as 10. The X-ray diffraction pattern of each powder was measured using CuKα as the X-ray source.

Each powder had a diffraction angle 2θ value of 17, 3
Since diffraction peaks typical of spinel-type crystals appeared around 6, 38, 44, and 48, it was confirmed that the oxide of this comparative example had a spinel crystal structure. The weight of the oxide contained in the positive electrode of this comparative example was 10.0 ± 0.2 g in all cases. This measured value was used for calculation of the manganese elution rate described later.

Using the oxide M10, a positive electrode slurry was prepared in the same manner as in Example 1. Lithium-manganese oxide,
The mixing ratio of natural graphite and polyvinylidene fluoride was 90: 6: 4 by weight. The slurry was applied to the surface of a positive electrode current collector made of an aluminum foil having a thickness of 20 μm by a doctor blade method, and dried at 100 ° C. for 2 hours to produce a positive electrode. The coating weight of the oxide on one side of the current collector was 20 ± 1 mg / cm ² .

Next, a negative electrode produced in the same procedure as in Example 1 was used. By combining a positive electrode, a negative electrode using the oxide M10, and a polyethylene separator having a thickness of 25 μm, a cylindrical battery having a height of 65 mm and a diameter of 18 mm was obtained.
0 were assembled. This battery is designated as B10.

The electrolytic solution used in this comparative example is the electrolytic solution S1 having the composition used in Example 1. The rated capacity of the battery B10 manufactured in this comparative example was 0.90 Ah. The initial capacity measured by the method of Example 1 was 0.90 Ah.

Batteries B of Examples 1 and 2 and Comparative Examples 1 and 2
For B10 to B10, after measuring the initial capacity described in Example 1, the charging current was 0.45 A, the constant current of 4.2 V was 5 at a constant current-constant voltage.
After charging for an hour, the battery was left in a charged state at 60 ° C. in a constant temperature bath. After standing for 30 days, the battery was returned to room temperature, and the discharge current was reduced to 0.
The battery was discharged to 2.8 V at 45 A.

Further, the battery was charged at a constant current-constant voltage of 0.45 A and 4.2 V for 5 hours, then discharged to 2.8 V at a discharge current of 0.45 A, and the discharge capacity of the battery was measured. The ratio of the discharge capacity obtained after the standing test to the initial capacity was determined, and the capacity recovery rate of the battery was calculated.

Next, the battery was disassembled, and the electrode group and the battery can were immersed in separate dimethoxyethane for several days to extract manganese ions dissolved in the electrolytic solution. Manganese ions dissolved in each dimethoxyethane solution were quantified by induction plasma emission analysis.

Further, the negative electrode was taken out of the electrode group, immersed in hydrochloric acid, and manganese deposited on the negative electrode surface was dissolved in hydrochloric acid. Manganese ions dissolved in the hydrochloric acid solution were quantified by induction plasma emission analysis.

The sum of the amount of manganese present in the electrolyte and the amount of manganese present in the negative electrode was divided by the amount of manganese calculated from the weight of the positive electrode at the time of assembling the battery, and the manganese elution rate of batteries B1 to B10 was determined.

Table 1 summarizes the capacity recovery rate and manganese elution rate of each battery. Batteries having a capacity recovery rate of 85% or more and a manganese elution rate of less than 5% were batteries B1 to B7. However, battery B8 having a low ethyl methyl carbonate composition, battery B9 having a high ethyl methyl carbonate composition,
In the battery B10 using the positive electrode having a Li / Mn ratio of less than 0.54, defects were found in any of the initial capacity, the manganese elution rate, and the capacity recovery rate.

[Embodiment 3] The lithium-manganese oxide used in this embodiment has the same specifications as M3 of the embodiment 1. A positive electrode using this oxide was produced in the same procedure as in Example 1. A 1-methyl-2-pyrrolidone solution of the oxide M3, natural graphite, and polyvinylidene fluoride was added and kneaded sufficiently to obtain a positive electrode slurry. The mixing ratio of lithium-manganese oxide, natural graphite, and polyvinylidene fluoride was 91.2: 4.8: 4 by weight. This slurry was applied to the surface of a positive electrode current collector made of an aluminum foil having a thickness of 20 μm by a doctor blade method. This was dried at 100 ° C. for 2 hours to produce a positive electrode. The coating weight of the oxide per one side of the current collector of this example was 20 ± 1 mg /
cm ² , the weight of the oxide M3 contained in the positive electrode was 1
It was 0.1 ± 0.2 g.

As the negative electrode, one prepared in the same procedure as in Example 1 was used. Combining a positive electrode using the oxide M3, a negative electrode and a polyethylene separator having a thickness of 25 μm,
Ten cylindrical batteries having a height of 65 mm and a diameter of 18 mm were assembled. This battery is designated as B11. The electrolytic solution composition used in this example is the electrolytic solution S1 having the composition used in Example 1. Both the rated capacity and the initial capacity of the battery B11 manufactured in this example were 0.91 Ah.

Embodiment 4 The lithium-manganese oxide used in the present embodiment has the same specifications as M3 of the embodiment 1. A positive electrode using this oxide was produced in the same procedure as in Example 1. A 1-methyl-2-pyrrolidone solution of the oxide M3, natural graphite, and polyvinylidene fluoride was added and kneaded sufficiently to obtain a positive electrode slurry. The mixing ratio of lithium-manganese oxide, natural graphite, and polyvinylidene fluoride was 83: 13: 4 by weight.

This slurry was applied to the surface of a positive electrode current collector made of an aluminum foil having a thickness of 20 μm by a doctor blade method. The coating thickness was set to be 1.08 times larger than that of Example 1, and the coating weight of the oxide per one side of the current collector was adjusted to be 20 ± 1 mg / cm ^2. It dried at 100 degreeC for 2 hours, and produced the positive electrode.

In this embodiment, since the composition of the positive electrode active material was small, the weight of the oxide M3 contained in the positive electrode was
3 and all decreased to 9.2 ± 0.2 g.

The negative electrode used was the same as that prepared in Example 1. Combining a positive electrode using the oxide M3, a negative electrode and a polyethylene separator having a thickness of 25 μm,
Ten cylindrical batteries having a height of 65 mm and a diameter of 18 mm were assembled. This battery is designated as B12. The electrolytic solution composition used in this example is the electrolytic solution S1 having the composition used in Example 1. Both the rated capacity and the initial capacity of the battery B12 produced in this example were 0.81 Ah.

Example 5 A positive electrode having the same specifications as in Example 1 was produced using the lithium-manganese oxide M3 used in Example 1. In this example, the coating weight of the oxide per one side of the current collector was 30 ± 1 mg / cm ² , and the weight of the oxide M3 contained in the positive electrode was all 10.5 ± 0.2 g.

The negative electrode used in this example was manufactured in the same procedure as in Example 1. By combining a positive electrode, a negative electrode using the oxide M3, and a polyethylene separator having a thickness of 25 μm, ten cylindrical batteries having a height of 65 mm and a diameter of 18 mm were assembled. This battery is designated as B13. The electrolytic solution composition used in this example is the electrolytic solution S1 having the composition used in Example 1.

In this embodiment, as the thickness of the positive electrode mixture increases,
The positive electrode active material increased, and the rated capacity of the battery B13 produced in this example was 0.93 Ah.

The three types of batteries B11 of Examples 3, 4, and 5
After measuring the initial capacity of each of the batteries B12 and B13 in total of 30 batteries according to Example 1, the charging current was 0.45.
A: After charging for 5 hours at a constant current-constant voltage of 4.2 V, the battery was left in a charged state at 60 ° C. in a constant temperature bath. After leaving for 30 days, the battery is returned to room temperature, and the discharge current is 2.8 V at 0.45 A.
Discharged until

Further, the battery was charged at a constant current-constant voltage of 0.45 A and 4.2 V for 5 hours, then discharged at a discharge current of 0.45 A to 2.8 V, and the discharge capacity of the battery was measured.

The ratio of the discharge capacity obtained after the standing test to the initial capacity was determined, and the capacity recovery rate of the battery was calculated.

Next, each battery was disassembled, and the electrode group and the battery can were immersed in separate dimethoxyethane for several days to extract manganese ions dissolved in the electrolyte. Manganese ions dissolved in the dimethoxyethane solution were quantified by induction plasma emission analysis.

Further, the negative electrode was taken out from the electrode group and immersed in hydrochloric acid to dissolve manganese deposited on the surface of the negative electrode in hydrochloric acid. Manganese ions dissolved in the hydrochloric acid solution were quantified by induction plasma emission analysis. The sum of the amount of manganese present in the electrolyte and the amount of manganese present in the negative electrode was assigned by the amount of manganese calculated from the weight of the positive electrode at the time of battery assembly, and the manganese elution rate was determined.

Table 1 shows the batteries B11, B12, and B1 of the present invention.
3 shows a capacity recovery rate and a manganese elution rate. The capacity recovery rate of these batteries was 85% or more, and the manganese elution rate was less than 5%. The present invention made it possible to improve battery storage characteristics and suppress manganese elution.

In the above embodiments, the graphite material was used for the negative electrode. However, it does not depend essentially on the type of the negative electrode, the electrolytic solution, the type of the electrolyte and the state of existence. Therefore, the negative electrode active material is not limited to natural graphite, artificial graphite, carbon fiber, vapor grown carbon fiber, pitch-based carbonaceous material, needle coke, petroleum coke,
Polyacrylonitrile-based carbon fiber, carbonaceous material such as carbon black, or amorphous carbon material synthesized by thermal decomposition of a 5- or 6-membered cyclic hydrocarbon or cyclic oxygen-containing organic compound, or polyacene; Conductive polymer material composed of polyparaphenylene, polyaniline, polyacetylene, or SnO, GeO ₂ , SnS
_{iO 3, SnSi 0.5 O 1.5,} SnSi 0.7 Al 0. 1 B 0.3 P
An oxide of a Group 14 or Group 15 element represented by _0.2 O _3.5 , SnSi _0.5 Al _0.3 B _0.3 P _0.5 O _4.15 , indium oxide, zinc oxide, or Li ₃ F
eN ₂ , or Fe ₂ Si ₃ , FeSi, FeSi ₂ , M
A silicide represented by g ₂ Si can be used.

Also, lithium or a metal alloying with lithium, ie, aluminum, tin, silicon, indium, gallium, and magnesium can be used for the negative electrode. Even when a negative electrode containing a material selected from these negative electrode active material groups and the positive electrode described in Example 1 were combined, the battery of the present invention had a capacity recovery rate of 85% or more and a manganese elution rate of less than 5%. It has become possible to improve storage characteristics and suppress manganese elution.

Further, a film held in a polymer of ethylene oxide, acrylonitrile, vinylidene fluoride, methyl methacrylate, and hexafluoropropylene was prepared, and the positive electrode and the negative electrode were integrated through the film using a press machine. A battery impregnated with the electrolytic solution S1 described in Example 1 can also be manufactured. Also in this case, the capacity recovery rate of the battery of the present invention was 85% or more and the manganese elution rate was less than 5%, and the present invention made it possible to improve the battery storage characteristics and suppress the manganese elution.

[Embodiment 6] The oxides M1 to M of the embodiment 1
Using No. 5, five types of positive electrodes were produced in the same manner as in the example. The mixing ratio of lithium-manganese oxide, natural graphite, and polyvinylidene fluoride of each positive electrode was 90: 6: 4 by weight.
And The coating weight of the oxide on one side of the aluminum foil current collector was 20 ± 1 mg / cm ² , and the weight of the oxide contained in the positive electrode was 8.9 ± 0.2 g in all cases.

The negative electrode was manufactured by the following method. An amorphous carbon powder having an average particle size of 5 μm (made by Kureha Chemical) and polyvinylidene fluoride are mixed at a weight ratio of 9: 1, 1-methyl-2-pyrrolidone is added as an organic solvent, and the mixture is sufficiently kneaded. A negative electrode slurry was prepared. This was applied to the surface of a negative electrode current collector made of a copper foil having a thickness of 18 μm by a doctor blade method. The dimensions of the negative electrode application surface are 56 mm in width × 51 mm in length. This was dried at 100 ° C. for 2 hours to produce a negative electrode.

Combining a positive electrode using the oxide M1, a negative electrode, and a polyethylene separator having a thickness of 25 μm,
A cylindrical battery having a height of 65 mm and a diameter of 18 mm was assembled. This battery is designated as B14. Similarly, oxide M2
A cylindrical battery 1 having the same shape was manufactured by combining a positive electrode, a negative electrode containing M5, and a polyethylene separator having a thickness of 25 μm. These batteries are designated B15 and B1 respectively.
6, B17 and B18. The number of batteries was 10 for each positive electrode, and the total number was 50.

The rated capacity and the initial capacity of the batteries B14 to B18 produced in this example were both 0.80 Ah.

About 50 ml of the electrolyte was injected into each of the 50 batteries of the above five types. The composition of the electrolytic solution used in this example is a non-aqueous electrolytic solution obtained by dissolving LiBF ₄ equivalent to 1 mol / liter in a mixed solvent of propylene carbonate and ethyl methyl carbonate. The volume ratio of propylene carbonate to ethyl methyl carbonate was 1: 1. This electrolyte is referred to as S14.

Example 7 The positive electrode active material M3 of Example 1
, A negative electrode of Example 7, and a thickness of 25 μm.
m with a polyethylene separator of height 6
A cylindrical battery of 5 mm × 18 mm in diameter was assembled. The number of manufactured batteries was set to 20.

In 10 of these batteries, the volume ratio of propylene carbonate to ethyl methyl carbonate was 1:
LiB equivalent to 1 mol / l in a mixed solvent of 0.3
About 4 ml of a non-aqueous electrolyte in which F ₄ was dissolved was injected. The electrolyte used here is referred to as S19, and the battery is referred to as B19.

Further, the remaining 10 batteries have a volume ratio of 1:
About 4 ml of an electrolyte obtained by dissolving LiBF ₄ in 0.7 propylene carbonate and ethyl methyl carbonate was injected. The type and concentration of the electrolyte are the same as the electrolyte S19. The electrolyte used here is denoted as S20, and the battery is denoted as B20.

The rated capacity of the two types of batteries manufactured in this example is 0.80 Ah based on the filling amount of the positive electrode active material. The initial capacities of these batteries were measured under the same conditions as in Example 1. As a result, the initial capacities of batteries B6 and B7 were equal to the rated capacities and were 0.80 Ah.

[Comparative Example 3] The positive electrode active material M3 of Example 1
, A negative electrode of Example 7, and a polyethylene separator having a thickness of 25 μm, and a height of 65 mm ×
A cylindrical battery having a diameter of 18 mm was assembled. The number of manufactured batteries was 20. An electrolytic solution obtained by dissolving LiBF ₄ in propylene carbonate and ethyl methyl carbonate in a volume ratio of 1: 0.1 was added to about 10 m of these batteries for about 4 m.
1 was injected. The electrolyte used here was S21 and the battery was B2
Notated as 1.

Further, the volume ratio of 1: 0.9 to 10 batteries was
About 4 ml of an electrolytic solution obtained by dissolving LiBF ₄ in propylene carbonate and ethyl methyl carbonate was injected.
The type and concentration of the electrolyte are the same as those of the electrolytic solution S21. The electrolyte used here is referred to as S22, and the battery is referred to as B22.

The rated capacity of the two types of batteries manufactured in this comparative example is 0.80 Ah based on the filling amount of the positive electrode active material. The initial capacities of these batteries were measured in the same manner as in Example 1. The initial capacity of the battery B22 of this comparative example was a value according to the rated capacity, but the initial capacity of the battery B21 was lower than the rated capacity and was 0.59 Ah. The reason for this decrease is
This is an increase in the resistance of the electrolyte due to a decrease in ethyl methyl carbonate.

Comparative Example 4 The lithium-manganese oxide used in this comparative example was prepared by mixing a predetermined amount of electrolytic MnO ₂ and Li ₂ CO ₃ and heat-treating the mixture at 900 ° C. in the atmosphere to obtain a molar ratio of lithium to manganese. Different lithium-manganese oxides were synthesized. The synthesized oxide powder has an average particle diameter of 20 μm and a specific surface area of 1 m as measured by a nitrogen adsorption method.
^{The 2} / g and Li / Mn ratio were 0.51. This oxide is denoted as M10. The X-ray diffraction pattern of each powder was measured using CuKα as the X-ray source. In any of the powders, the diffraction angle 2θ value is 17, 36, 38, 44, 48.
Since a diffraction peak typical of a spinel-type crystal appeared in the vicinity, it was confirmed that the oxide of this comparative example had a spinel crystal structure.

The weight of the oxide contained in the positive electrode of this comparative example was 8.9 ± 0.2 g in all cases. This measured value was used for calculation of the manganese elution rate described later.

A positive electrode using the oxide M10 was manufactured in the same procedure as in Example 1. A positive electrode slurry was prepared by adding an oxide, natural graphite, and a 1-methyl-2-pyrrolidone solution of polyvinylidene fluoride and kneading the mixture. The mixing ratio of lithium-manganese oxide, natural graphite, and polyvinylidene fluoride was 90: 6: 4 by weight. This slurry was applied to the surface of a positive electrode current collector made of an aluminum foil having a thickness of 20 μm by a doctor blade method. This one
It dried at 00 degreeC for 2 hours, and produced the positive electrode. The coating weight of the oxide on one side of the current collector was 20 ± 1 mg / cm ² .

As the negative electrode, a negative electrode produced in the same procedure as in Example 1 was used. By combining a positive electrode, a negative electrode using the oxide M10, and a polyethylene separator having a thickness of 25 μm, ten cylindrical batteries having a height of 65 mm and a diameter of 18 mm were assembled. This battery is designated as B23. The composition of the electrolytic solution used in this comparative example is the same as the electrolytic solution S14 used in Example 6. The rated capacity of the battery B23 produced in this comparative example was 0.3.
80 Ah. The initial capacity measured by the method of Example 1 was also 0.80 Ah.

B produced in Examples 6 and 7 and Comparative Example 2
The initial capacity of each of the batteries 14 to B23 was measured in the same manner as in Example 1. However, the end voltage at the time of discharging was changed from 2.8V to 2.5V.

Next, the battery was charged at a constant current-constant voltage of 0.45 A and 4.2 V for 5 hours, and then left in a charged state at 60 ° C. in a constant temperature bath. After being left for 30 days, the battery was returned to room temperature and discharged to 2.5 V at a discharge current of 0.45 A.

Further, the battery was charged at a constant current-constant voltage of 0.45 A and 4.2 V for 5 hours, then discharged at a discharge current of 0.45 A to 2.5 V, and the discharge capacity of the battery was measured.

The ratio of the discharge capacity obtained after the standing test to the initial capacity was determined, and the capacity recovery rate of the battery was calculated.

Next, each battery was disassembled, and the electrode group and the battery can were immersed in separate dimethoxyethane solutions for several days to extract manganese ions dissolved in the electrolyte solution. Manganese ions dissolved in the dimethoxyethane solution were quantified by induction plasma emission analysis.

Further, the negative electrode was taken out from the electrode group, immersed in hydrochloric acid, and manganese deposited on the negative electrode surface was dissolved in hydrochloric acid. Manganese ions dissolved in the hydrochloric acid solution were quantified by induction plasma emission analysis. The sum of the amount of manganese present in the electrolyte and the amount of manganese present in the negative electrode was assigned by the amount of manganese calculated from the weight of the positive electrode at the time of battery assembly, and the manganese elution rate was determined.

Table 1 shows the capacity recovery rate and manganese elution rate of each battery. Batteries having a capacity recovery rate of 85% or more and a manganese elution rate of less than 5% were batteries B14 to B20 of the present invention. However, in the battery B21 having a low ethyl methyl carbonate composition, the battery B22 having a high ethyl methyl carbonate composition, and the battery B23 using a positive electrode having a Li / Mn ratio of less than 0.54, the initial capacity, the manganese elution rate, and the capacity recovery rate were low. Some of them had drawbacks.

Example 8 FIG. 2 shows an example of a prismatic lithium secondary battery using the lithium-manganese oxide M3 of Example 1, the natural graphite of Example 1, and the electrolyte of Example 1. is there.

The composition of the lithium-manganese oxide M3, the positive electrode mixture, the negative electrode mixture and the electrolyte, and the procedure for preparing the electrodes are the same as those in Example 1. The shape of the mixture-applied surface of the positive electrode and the negative electrode produced in this example is a strip having a height of 38 mm and a width of 32 mm.

The strip-shaped positive electrode 1 containing the oxide M3 of the present invention was inserted into a bag-shaped separator 3 and alternately laminated with the strip-shaped negative electrode 2. The positive electrode lead 5 and the negative electrode lead 7 were welded to the upper part of each electrode, and connected to the external terminals 11 and 12 on the bottom surface of the battery cover 6. The battery lid 6 was provided with a safety valve 8 for releasing the pressure inside the battery. Battery can 4 and lid 6
Was subjected to laser welding, an electrolyte was introduced from the injection port 10, and the injection port 10 was welded to seal the battery.

FIG. 3 shows an example of a battery pack for a notebook personal computer on which the eight rectangular lithium secondary batteries shown in FIG. 2 are mounted. The eight prismatic lithium secondary batteries used were connected in four series-two parallel to assemble the battery pack 13 shown in FIG. The outer dimensions of the battery pack 13 are a height of 34 mm × a width of 14 mm.
It is 0 mm x 58 mm deep.

The control panel 14 controls the charging / discharging current of each cell 15 and connects to a device or a charger using the positive external terminal 16, the negative external terminal 17, and the common terminal 18.
The battery pack 13 using the eight batteries of the present invention had an average discharge of 15.2 V, a rated discharge capacity of 3.0 Ah, a discharge energy of 46 Wh, and an energy density of 167 Wh / l. This battery pack is denoted as P1.

By combining the same type of electrode and electrolyte used in Comparative Example 2, four rectangular lithium secondary batteries shown in FIG. 2 were manufactured. A battery pack 13 shown in FIG. 3 was assembled by connecting eight batteries of the same specification in four series and two parallel. The average discharge, rated discharge capacity, discharge energy, and energy density of the battery pack 13 were 14.8 V, 3.0 Ah, respectively.
It was 44 Wh and 161 Wh / l. This battery pack is denoted as P2.

The battery packs P1 and P2 are charged with a charging current of 1.5.
A, charging was performed at 16.8 V constant current-constant voltage for 5 hours, and the battery packs P1 and P2 were left in a 60 ° C. constant temperature bath in the charged state. After 30 days, discharge current 1.5 at room temperature
A, The battery was discharged to a discharge end voltage of 11.2 V.

Next, the battery was charged at a charge current of 1.5 A at a constant voltage of 16.8 V for 5 hours, and then discharged to a discharge current of 1.5 A and a discharge end voltage of 11.2 V. I asked. The capacity recovery rates of the battery packs P1 and P2 were 82% and 51%, respectively, and it was found that the battery pack P1 using the battery of the present invention had better storage characteristics under a high-temperature environment.

FIG. 4 shows an example in which the battery pack 13 of the present invention is mounted on a notebook computer. Reference numeral 19 denotes a keyboard unit, and reference numeral 20 denotes a liquid crystal display unit. By using the battery of the present invention, battery storage characteristics in a high-temperature environment or during battery charging can be improved.

[Embodiment 9] In this embodiment, lithium-
Using the manganese oxide M3, the natural graphite of Example 1, and the electrolytic solution, a prismatic lithium secondary battery having the configuration shown in FIG. 2 was produced. The rated capacity of the battery is 250 Wh. The height, width, and depth of the battery are 116 mm, 160 mm, and 4 mm, respectively.
5 mm. The number of prismatic lithium secondary batteries manufactured in this example is eight. The dimensions of the coated surfaces of the positive and negative electrodes are height 1
The size was set to 00 mm × width 150 mm × electrode thickness 0.6 mm.

In the same manner as in Example 1, a positive electrode and a negative electrode were produced with a mixture composition having the same specifications. As the electrolytic solution used in the present invention, the electrolytic solution S1 having the same specifications as used in Example 1 was used.
The total capacity of the battery is 65 Ah, the average operating voltage is 3.8 V, and the discharge energy is 250 Wh. In order to avoid contact with the negative electrode during electrode lamination, the positive electrode 1 was inserted into a polyethylene separator 3 processed into an envelope shape. An electrode group in which this and the negative electrode 2 were alternately laminated was inserted into the battery can 4. The positive electrode 1 was connected to the positive electrode lead 5, and was electrically connected to the positive electrode external terminal 11 from the bottom of the battery lid 6. Further, the negative electrode 2 was connected to the negative electrode lead 7, and the negative electrode lead 7 was electrically connected to the negative electrode external terminal 12 from the bottom surface of the battery cover 6.

After the battery lid 6 and the battery can 4 were laser-welded, a non-aqueous electrolyte was vacuum-injected from the inlet 10 of the battery lid 6 and the inlet 10 was sealed. In order to release the internal pressure of the battery, a safety valve 8 having a burst valve made of Al foil was attached to the battery lid 6. With this configuration, electrochemical energy can be extracted from the positive electrode external terminal 11 and the negative electrode external terminal 12 and can be recharged.

A 2 kWh assembled battery module in which eight 250 Wh lithium secondary batteries manufactured in this example were connected in series was assembled, and an assembled battery module 21 including the 20 assembled batteries was mounted on an electric vehicle 22. FIG. 5 shows the configuration of the electric vehicle.

A ventilation port 23 is provided on the front of the electric vehicle so that outside air flows from the hood to the vehicle body during normal running. The assembled battery module 21 was installed inside the hood of the electric vehicle.

When the driver operates the control device 24 with the steering wheel, the converter 25 is operated to increase or decrease the output from the battery module 21. The electric vehicle was driven by driving the motor 26 and the wheels 27 using the electric power supplied from the converter 25. Even when the temperature inside the electric vehicle or the body of the vehicle increases due to direct sunlight or light reflected from the road surface, the battery of the present invention has excellent high-temperature storage characteristics and a small decrease in battery capacity.

Further, the same effect can be obtained by using the battery of the present invention for a hybrid type electric vehicle using both a gasoline engine and a battery.

[Embodiment 10] FIG. 6 shows an example of a wheelchair 28 for medical care provided with a power supply 21 composed of the assembled battery or the module of 3 to 5 assembled batteries manufactured in the ninth embodiment.

The angle can be adjusted by operating the controller 29 while the user is in the medical care wheelchair 28 by operating the controller provided on the backrest seat 30 and the footrest seat 31. By utilizing this function, the footrest sheet 31 is lowered when the user gets on and off, and the backrest seat 30 and the footrest sheet 31 are leveled when the user rests.

Since the wheelchair 28 for medical care has the wheels 27 for movement, it is possible for the user to move to the target position by operating the controller 29.

The wheelchair 28 for medical and nursing care of this embodiment is a product in which stable operation is guaranteed because the battery has excellent storage characteristics even in a high-temperature environment.

The assembled battery system according to the present invention is applied to the sixth and seventh embodiments.
And 8, besides the notebook computer, electric vehicle, and wheelchair for medical care, power-saving electronic devices such as personal computers, pen-input computers, notebook computers, fax machines, mobile phones, copiers, stationary televisions,
The present invention can be applied to a head mounted television, a liquid crystal television, a video, a video camera, an electronic organizer, a calculator, an electronic organizer with a communication function, a toy, and the like.

Further, equipment systems that require a large power / capacity power supply, for example, a large-sized computer, a power tool, a vacuum cleaner, an air conditioner, a game device having a virtual reality function, an electric bicycle, a medical care use It can be installed in products such as walking aids, mobile beds for medical care, escalators, elevators, forklifts, golf carts, emergency power supplies, road conditioners, and power storage systems. Is obtained.

[0127]

According to the present invention, a lithium secondary battery having excellent capacity retention characteristics can be obtained by suppressing the elution of manganese from the lithium-manganese oxide.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a cylindrical lithium secondary battery of the present invention.

FIG. 2 is a schematic sectional view of the prismatic lithium secondary battery of the present invention.

FIG. 3 is a configuration diagram of a battery pack incorporating four prismatic lithium secondary batteries of the present invention.

FIG. 4 is a schematic view of a notebook computer equipped with the battery pack of the present invention.

FIG. 5 is a schematic view of an electric vehicle using a 250 Wh battery of the present invention.

FIG. 6 is a schematic view of a wheelchair for medical care using a 250 Wh battery of the present invention.

[Description of Signs] 1 ... Positive electrode, 2 ... Negative electrode, 3 ... Polyethylene separator,
4 Battery can, 5 Positive electrode lead, 6 Battery cover, 7 Negative electrode lead, 8 Safety valve, 9 Gasket, 10 Liquid inlet, 1
DESCRIPTION OF SYMBOLS 1 ... positive external terminal, 12 ... negative external terminal, 13 ... battery pack, 14 ... control panel, 15 ... unit cell, 16 ... positive external terminal, 17 ... negative external terminal, 18 ... common terminal, 19
... keyboard part, 20 ... liquid crystal display part, 21 ... assembled battery module, 22 ... electric vehicle, 23 ... vent, 24 ... control device, 25 ... converter, 26 ... motor, 27 ... wheel, 2
8 ... Medical care wheelchair, 29 ... Controller, 30 ...
Backrest seat, 31 ... footrest seat.

────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] July 30, 1999

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

Wherein said electrolytic solution, ethylene oxide, acrylonitrile, vinylidene fluoride, methyl methacrylate, a non-aqueous electrolyte according to claim 1, 2 or 3 is held in the polymer selected from hexafluoropropylene two Next battery.

5. A method according to claim 1, lithium, aluminum, tin, silicon, indium, gallium, selected metals or their alloys than magnesium, or one or more kinds of the negative electrode active material composed of the metal or alloy and lithium alloys 5. The non-aqueous electrolyte secondary battery according to any one of items 1 to 4 .

6. A natural graphite, artificial graphite, carbon fiber, vapor grown carbon fiber, pitch-based carbonaceous material, needle coke, petroleum coke, polyacrylonitrile-based carbon fiber,
A carbon black carbonaceous material, an amorphous carbon material synthesized by thermally decomposing a 5-membered or 6-membered cyclic hydrocarbon, a cyclic oxygen-containing organic compound, polyacene, polyparaphenylene, polyaniline, polyacetylene Conductive polymer material, SnO, GeO ₂ , SnSiO ₃ , SnSi _{0.5
O 1.5, SnSi 0.7 Al 0.1 B} 0.3 P 0. 2 O 3.5, SnSi
_0.5 Al _0.3 B _0.3 P _0.5 O _4.15 Group 14 or Group 15 element oxide, indium oxide, zinc oxide,
Li ₃ FeN ₂ , Fe ₂ Si ₃ , FeSi, FeSi ₂ , M
The non-aqueous electrolyte secondary battery according to claim 1 comprising one or more selected from the negative electrode active substance group consisting of silicides represented by g ₂ Si.

7. The non-aqueous electrolyte secondary battery characterized in that the non-aqueous electrolyte secondary battery was each other in series or / and connected battery pack in parallel according to any one of claims 1-6.

8. The electrical device, characterized in that mounted one or more non-aqueous electrolyte secondary battery according to any one of claims 1-6.

9. that a non-aqueous electrolyte secondary battery equipped with a battery pack connected each other in series or / and parallel electrical apparatus according to claim according to any of claims 1-6.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Correction contents]

[0010]

Means for Solving the Problems As a result of the present inventors working on technical problems for preventing manganese elution, a series of spinel-type lithium-manganese oxides having a defined chemical composition, crystal structure, etc. the weight composition of the positive electrode conductive agent, by optimizing the electrolyte composition was found Rukoto greatly suppressed manganese elution. That is, a specific lithium-manganese oxide and a positive electrode containing a conductive agent, a main solvent consisting of ethylene carbonate or propylene carbonate, and lithium tetrafluoroborate dissolved in a mixed solvent of ethyl methyl carbonate The combination with the electrolytic solution improved the thermal stability of the positive electrode, and suppressed the manganese elution reaction into the electrolytic solution.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0063

[Correction method] Change

[Correction contents]

Table 1 summarizes the capacity recovery rate and manganese elution rate of each battery. Batteries having a capacity recovery rate of 85% or more and a manganese elution rate of less than 5% were batteries B1 to B7. However, ethylmethyl carbonate composition is low battery B8, contact and, in the battery B10 Li / Mn ratio using the positive electrode of less than 0.54, the initial capacity, manganese dissolution rate, the drawback either of capacity recovery rate observed Was.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name]

[Correction method] Change

[Correction contents]

Combining a positive electrode using the oxide M1, a negative electrode, and a polyethylene separator having a thickness of 25 μm,
A cylindrical battery having a height of 65 mm and a diameter of 18 mm was assembled. This battery is designated as B14. Similarly, oxide M2
A cylindrical battery 1 having the same shape was manufactured by combining a positive electrode, a negative electrode containing M5, and a polyethylene separator having a thickness of 25 μm. B14, B1
5, B16, B17, and B18. The number of batteries was 10 for each positive electrode, and the total number was 50.

[Procedure amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0104

[Correction method] Change

[Correction contents]

Table 1 shows the capacity recovery rate and manganese elution rate of each battery. Batteries having a capacity recovery rate of 85% or more and a manganese elution rate of less than 5% were batteries B14 to B20 of the present invention. However, in the battery B23 Li / Mn ratio using the positive electrode of less than 0.54 ethyl methyl carbonate composition to the low battery B2 1 rabbi, initial capacity, manganese dissolution rate,
Disadvantages were seen in any of the capacity recovery rates.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI // A61G 5/04 505 A61G 5/04 505 (72) Inventor Shuko Yamauchi 7-1-1, Omika-cho, Hitachi City, Ibaraki Pref. Hitachi, Ltd., Hitachi Research Laboratory (72) Inventor Akihiro Goto 7-1-1, Omika-cho, Hitachi City, Ibaraki Prefecture Hitachi, Ltd. Hitachi Research Laboratory (72) Inventor, Hisashi Ando 7-1-1, Omika-cho, Hitachi City, Ibaraki Prefecture No. 1 In Hitachi Research Laboratory, Hitachi, Ltd. (72) Inventor Ren Muranaka 7-1-1, Omika-cho, Hitachi City, Ibaraki Prefecture In Hitachi Research Laboratory, Hitachi, Ltd.

Claims (10)

[Claims] 1. A mixed solution of a lithium-manganese oxide having a spinel crystal structure composed of lithium and manganese, a positive electrode containing a conductive agent, a negative electrode, a main solvent composed of ethylene carbonate or propylene carbonate, and ethyl methyl carbonate. A non-aqueous electrolyte secondary battery including an electrolytic solution in which lithium tetrafluoroborate is dissolved, wherein the sum of the weight of manganese contained in the negative electrode and the electrolytic solution eluted from the lithium-manganese oxide in the positive electrode is the positive electrode. A non-aqueous electrolyte secondary battery, wherein the content is 5% or less of the total weight of manganese contained therein. 2. The lithium / manganese oxide contained in the lithium-manganese oxide has a molar ratio of lithium / manganese of 0.54 to 0.61 and a volume ratio of ethyl methyl carbonate to a main solvent of ethylene carbonate or propylene carbonate of 0 to 0. 2. The non-aqueous electrolyte secondary battery according to claim 1, wherein the number is from 0.3 to 0.7. 3. The lithium-manganese oxide having an a-axis lattice constant of 0.8210 to 0.8235 nm.
Or the non-aqueous electrolyte secondary battery according to 2. 4. A positive electrode coated with a lithium-manganese oxide, wherein the weight composition ratio of the conductive agent to the lithium-manganese oxide is 5 to 15%, and the average particle size of the conductive agent is 30 μm or less. Lithium per cm ^{2 of} surface-
The non-aqueous electrolyte secondary battery according to claim 1, 2 or 3, wherein the amount of manganese oxide carried is 20 to 30 mg. 5. The non-aqueous electrolyte according to claim 1, wherein the electrolyte is held in a polymer selected from ethylene oxide, acrylonitrile, vinylidene fluoride, methyl methacrylate, and hexafluoropropylene. Rechargeable battery. 6. A negative electrode active material comprising one or more metals selected from lithium, aluminum, tin, silicon, indium, gallium, and magnesium, or an alloy thereof, or an alloy of the metal or the alloy and lithium. 6. The non-aqueous electrolyte secondary battery according to any one of claims 1 to 5. 7. Natural graphite, artificial graphite, carbon fiber, vapor grown carbon fiber, pitch-based carbonaceous material, needle coke, petroleum coke, polyacrylonitrile-based carbon fiber,
A carbon black carbonaceous material, an amorphous carbon material synthesized by thermally decomposing a 5-membered or 6-membered cyclic hydrocarbon, a cyclic oxygen-containing organic compound, polyacene, polyparaphenylene, polyaniline, polyacetylene Conductive polymer material, SnO, GeO ₂ , SnSiO ₃ , SnSi _{0.5
O 1.5, SnSi 0.7 Al 0.1 B} 0.3 P 0. 2 O 3.5, SnSi
_0.5 Al _0.3 B _0.3 P _0.5 O _4.15 Group 14 or Group 15 element oxide, indium oxide, zinc oxide,
Li ₃ FeN ₂ , Fe ₂ Si ₃ , FeSi, FeSi ₂ , M
The non-aqueous electrolyte secondary battery according to claim 1 comprising one or more selected from the negative electrode active substance group consisting of silicides represented by g ₂ Si. 8. A non-aqueous electrolyte secondary battery comprising a plurality of non-aqueous electrolyte secondary batteries according to claim 1 connected in series or / and in parallel to form an assembled battery. 9. An electric device comprising at least one non-aqueous electrolyte secondary battery according to claim 1. 10. An electric device comprising an assembled battery in which a plurality of non-aqueous electrolyte secondary batteries according to claim 1 are connected in series or / and in parallel.