JP2002198048A - Nonaqueous electrolyte secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nonaqueous electrolyte secondary battery which is of high capacity and high output yet can keep high output for a long time. SOLUTION: The cylindrical lithium ion battery 20 has a group of electrodes with positive electrodes, negative electrodes and separators wound around, a connecting part for connecting the group of electrodes with each electrode terminal, and a nonaqueous electrolyte solution. As a positive electrode active substance, lithium manganate which has dissolution volume of manganese into nonaqueous electrolyte solution of not less than 5% in a lithium manganate standard at a region where electrode potential against metal lithium is not less than 4.8 V, and as a negative electrode active substance, graphite is used which can store and release lithium ion by charging and discharging.

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 an electrode group having a positive electrode, a negative electrode and a separator in a battery container, and a connecting portion for connecting the electrode group to each electrode terminal. The present invention relates to a non-aqueous electrolyte secondary battery using a positive electrode which contains a non-aqueous electrolyte and has an active material mixture containing a lithium manganese double oxide and a conductive material applied to both surfaces of a foil-shaped current collector.

[0002]

2. Description of the Related Art Lithium ion secondary batteries, which represent non-aqueous electrolyte secondary batteries, are mainly used for powering portable devices such as VTR cameras, notebook computers, and mobile phones, taking advantage of their high energy density. Have been. The internal structure of this battery is usually a wound structure as shown below. Each of the electrodes has a positive electrode and a negative electrode in a band shape in which an active material is applied to a metal foil, and a cross section is spirally wound so that the positive electrode and the negative electrode do not come into direct contact with each other with a separator interposed therebetween, thereby forming a wound group. . The wound group is housed in a cylindrical battery can serving as a battery container, and is sealed after the electrolyte is injected.

[0003] The outer diameter of a general cylindrical lithium ion secondary battery is called 18650 type, having a diameter of 18 mm.
It has a height of 65 mm and is widely used as a small consumer lithium ion battery. As the positive electrode active material of the 18650 type lithium ion secondary battery, lithium cobalt oxide having high capacity and long life is mainly used. The battery capacity is approximately 1.3 Ah to 1.7 Ah, and the output is about 10 W. It is about.

On the other hand, in the automobile industry, in order to cope with environmental problems, an electric vehicle having no exhaust gas and having only a battery as a power source, and a hybrid (using both an internal combustion engine and a battery as a power source) have been proposed. The development of electric vehicles has been accelerated and some of them have reached the stage of practical use. A battery serving as a power source for an electric vehicle is required to have characteristics capable of obtaining high output and high energy, and a lithium ion battery has attracted attention as a battery that meets these requirements.

In order to spread these electric vehicles, it is essential to reduce the price of the battery. For this purpose, it is required to use a low-cost battery material. Abundant manganese oxides are of particular interest,
Improvements have been made to improve the performance of batteries. In addition, batteries for electric vehicles are required to have not only high capacity but also high output that affects acceleration performance and the like, that is, reduction of internal resistance of the battery. This requirement can be met by using a lithium manganese double oxide such as lithium manganate having a large specific surface area as the positive electrode active material for the purpose of increasing the electrode reaction area.

[0006]

However, when a lithium manganese double oxide is used as the positive electrode active material, the battery performance deteriorates due to repetition of charge / discharge even if the initial capacity and the initial output are high. There is a problem that the battery has an early life. This naturally causes secondary problems such as early life of the vehicle and early battery replacement, and is a great hindrance to the spread of electric vehicles.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, an object of the present invention is to provide a non-aqueous electrolyte secondary battery capable of maintaining high output for a long time while having high capacity and high output.

[0008]

In order to solve the above problems, a first aspect of the present invention is to provide an electrode group having a positive electrode, a negative electrode and a separator in a battery container, and a method for connecting the electrode group to each electrode terminal. A non-aqueous electrolyte secondary using a positive electrode that contains a connection part and a non-aqueous electrolyte and has an active material mixture containing a lithium manganese double oxide and a conductive material applied to both surfaces of a foil-shaped current collector In the battery, in a region where the electrode potential with respect to metallic lithium is 4.8 V or more, the amount of manganese eluted into the nonaqueous electrolyte is 5% or more based on the lithium manganese double oxide. It is characterized in that graphite, which can insert and extract lithium ions by charge and discharge, is used as a negative electrode active material.

According to a second aspect of the present invention, a battery container includes an electrode group having a positive electrode, a negative electrode, and a separator, a connecting portion for connecting the electrode group to each electrode terminal, and a non-aqueous electrolyte. In a nonaqueous electrolyte secondary battery using a positive electrode in which an active material mixture containing a lithium manganese double oxide and a conductive material is coated on both surfaces of a foil-like current collector, the electrode potential with respect to metallic lithium is 4.8 V In the above region, the amount of manganese eluted in the non-aqueous electrolyte is 7% or more based on the lithium manganese double oxide, and the lithium manganese double oxide is used as the positive electrode active material, and lithium ions are absorbed by charging and discharging. It is characterized in that releasable amorphous carbon is used for the negative electrode active material.

According to the present invention, in order to obtain a high-capacity, high-output non-aqueous electrolyte secondary battery, a lithium manganese double oxide can be inserted into the positive electrode active material, and lithium ions can be inserted into and discharged from the negative electrode active material by charging and discharging. Graphite or amorphous carbon is used, respectively. When graphite is used as the negative electrode active material, the elution amount of manganese into the nonaqueous electrolyte in the region where the electrode potential with respect to metallic lithium is 4.8 V or more is 5% based on the lithium manganese double oxide in the positive electrode active material. By using the above-mentioned lithium manganese double oxide, or when using amorphous carbon as the negative electrode active material, the positive electrode active material is used in a non-aqueous electrolyte in a region where the electrode potential with respect to metallic lithium is 4.8 V or more. By using a lithium manganese double oxide having a manganese elution amount of 7% or more based on the lithium manganese double oxide, a high output retention ratio can be secured. Therefore, according to the present invention, it is possible to realize a nonaqueous electrolyte secondary battery having a high capacity and a high output but a high output maintenance ratio.

In this case, if the ratio of Li / Mn of the lithium manganese composite oxide is less than 0.55, the capacity retention ratio decreases, and if it exceeds 0.6, the initial capacity decreases. The ratio of Li / Mn of the oxide is 0.1.
It is preferably 55 or more and 0.6 or less. At this time, if amorphous carbon is used as the negative electrode active material and the amount of manganese eluted into the non-aqueous electrolyte of the lithium manganese composite oxide is 7.5% or more based on the lithium manganese composite oxide, In addition, a high initial capacity and an initial output can be secured, and a high capacity maintenance rate and an output maintenance rate can be secured for a long time.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which a nonaqueous electrolyte secondary battery according to the present invention is applied to a cylindrical lithium ion battery used as a power supply for an electric vehicle will be described below with reference to the drawings.

(Preparation of positive electrode plate) As shown in FIG. 1, lithium manganate (LiMn ₂ O ₄ ) as a positive electrode active material
Powder, graphite powder and acetylene black as a conductive material, and polyvinylidene fluoride (PVDF) as a binder
Are mixed at a mass ratio of 83: 10: 2: 5, and N-methyl-2-pyrrolidone (NMP) as a dispersion solvent is added thereto,
The kneaded slurry is applied to an aluminum foil W1 having a thickness of 20 μm.
(Positive electrode current collector). At this time, an uncoated portion having a width of 30 mm was left on one side edge in the longitudinal direction of the positive electrode plate.
After drying, pressing and cutting, the width is 82 mm and the length is 342
cm, a positive electrode plate having an active material mixture application portion W2 and a thickness of 109 μm. The bulk density of the positive electrode active material mixture layer W2 is 2.65 g /
cm ³ . A cutout was made in the uncoated portion, and the remaining cutout was used as a positive electrode lead piece 2. Adjacent positive electrode lead pieces 2 were set at intervals of 50 mm, and the width of the positive electrode lead pieces 2 was set at 5 mm.

(Preparation of Negative Electrode Plate) A slurry prepared by adding 8 parts by mass of polyvinylidene fluoride as a binder to 92 parts by mass of a predetermined carbon powder, adding N-methyl-2-pyrrolidone as a dispersion solvent thereto and kneading the mixture. Is rolled copper foil W3 having a thickness of 10 μm.
(Negative electrode current collector). At this time, an uncoated portion having a width of 30 mm was left on one side edge in the longitudinal direction of the negative electrode plate.
Thereafter, drying, pressing, and cutting were performed to obtain a negative electrode plate having a width of 86 mm, a predetermined length described later, and a predetermined thickness of the active material application portion W4.
The negative electrode plate was compressed such that the porosity of the negative electrode active material layer W4 was about 35%. A cutout was made in the uncoated portion in the same manner as the positive electrode plate, and the remaining cutout was used as a negative electrode lead piece 3. Adjacent negative electrode lead pieces 3 are set at intervals of 50 mm.
Was 5 mm in width.

(Preparation of Battery) The above-prepared positive electrode plate and negative electrode plate were 90 m wide so that these two electrode plates did not come into direct contact with each other.
m, together with a polyethylene separator W5 having a thickness of 40 μm. At the center of the winding, a hollow cylindrical shaft core 1 made of polypropylene was used. At this time, the positive electrode lead piece 2 and the negative electrode lead piece 3 were located on both end faces on the opposite side of the winding group 6, respectively. Further, the length of the positive electrode plate, the negative electrode plate, and the separator was adjusted, and the diameter of the winding group 6 was adjusted to 38.
± 0.1 mm.

The positive electrode lead piece 2 is deformed, and all of the
After gathering and contacting the vicinity of the flange peripheral surface integrally projecting from the periphery of the positive electrode current collecting ring 4 substantially on the extension line of the shaft core 1 of the winding group 6, the positive electrode lead piece 2 and the flange peripheral surface are separated. The positive electrode lead piece 2 was connected to the flange peripheral surface by ultrasonic welding. On the other hand, the connection operation between the negative electrode current collector ring 5 and the negative electrode lead piece 3 was also performed in the same manner as the connection operation between the positive electrode current collector ring 4 and the positive electrode lead piece 2.

Thereafter, an insulating coating was applied to the entire peripheral surface of the flange portion of the positive electrode current collecting ring 4. For this insulating coating, a pressure-sensitive adhesive tape was used in which the base material was polyimide and one side thereof was coated with a pressure-sensitive adhesive composed of hexamethacrylate. This adhesive tape was wound one or more times from the peripheral surface of the flange portion to the outer peripheral surface of the winding group 6 to form an insulating coating, and the winding group 6 was inserted into a nickel-plated steel battery container 7. The outer shape of the battery container 7 is 40 mm, and the inner diameter is 39 mm.

A negative electrode lead plate 8 for electrical conduction is welded to the negative electrode current collecting ring 5 in advance. After the winding group 6 is inserted into the battery container 7, the bottom of the battery container 7 and the negative electrode lead plate 8 are connected to each other. Was welded.

On the other hand, a positive electrode lead 9 formed by laminating a plurality of aluminum ribbons is welded to the positive electrode current collecting ring 4 in advance, and the other end of the positive electrode lead 9 is sealed with the battery container 7. To the lower surface of the battery lid. The battery lid is provided with a cleavage valve 11 as an internal pressure release mechanism that is opened according to an increase in the internal pressure of the cylindrical lithium ion battery 20. The cleavage pressure of the cleavage valve 11 was set to about 9 × 10 ⁵ Pa. The battery lid includes a lid case 12 and a lid cap 13.
, A valve retainer 14 for maintaining airtightness, and a cleavage valve 11, which are stacked and assembled by caulking the periphery of the lid case 12.

A predetermined amount of a non-aqueous electrolyte is injected into the battery case 7, and then the battery case 7 is covered with the battery cover so that the positive electrode lead 9 is folded.
The cylindrical lithium-ion battery 20 was completed by caulking and sealing through the inside of the battery.

The non-aqueous electrolyte contains lithium hexafluorophosphate (L) in a mixed solution of ethylene carbonate, dimethyl carbonate and diethyl carbonate at a volume ratio of 1: 1: 1.
iPF ₆ ) dissolved at 1 mol / liter was used.
The cylindrical lithium-ion battery 20 is electrically operated in response to an increase in battery internal pressure, for example, PTC (Posit).
ive Temperature Coefficient) There is no current interruption mechanism such as an element.

In this embodiment, in the region where the electrode potential with respect to metallic lithium is 4.8 V or more, the amount of manganese eluted into the non-aqueous electrolyte is 5% or more of lithium manganate based on lithium manganate. Is used as the positive electrode active material, and graphite capable of occluding and releasing lithium ions by charge and discharge is used as the negative electrode active material, or the amount of manganese eluted into the nonaqueous electrolyte is 7% based on lithium manganate.
% Or more of lithium manganate was used as a positive electrode active material, and amorphous carbon capable of inserting and extracting lithium ions by charge and discharge was used as a negative electrode active material.

The electrode potential for metal lithium is 4.8 V
In the above region, the amount of manganese eluted into the non-aqueous electrolyte is
In order to specifically obtain lithium manganate of the above-mentioned predetermined percentage or more based on lithium manganate, the particle diameter is limited, the specific surface area is limited, and the synthesis raw material of lithium manganate and the synthesis conditions are controlled. There are various factors such as
Since the control factor and other factors are intertwined in a complicated manner, the amount of elution changes and the variation increases, it is difficult to specify all of the factors alone. In this embodiment, for this purpose, several lots of lithium manganate were prepared under various conditions, and lots having the above requirements were selected therefrom and used.

The amount of manganese eluted from lithium manganate was measured according to the following procedure. A part of the positive electrode prepared as described above was cut out, and the potential was held at a potential of 4.8 V or more in a nonaqueous electrolyte for 24 hours or more in a nonaqueous electrolyte using metallic lithium as a reference electrode, and manganese eluted in the nonaqueous electrolyte and a counter electrode. Was quantitatively analyzed with respect to the manganese precipitated on the substrate, and the total amount was calculated on the basis of lithium manganate. In the measurement of the manganese elution amount, the non-aqueous electrolyte is decomposed at a potential of 6 V or more.

[0025]

Next, an example of the cylindrical lithium ion battery 20 manufactured according to this embodiment will be described. A battery of a comparative example produced for comparison is also described.

Example 1 As shown in Table 1 below, in Example 1, lot No. 1 was used as the positive electrode active material. Using lithium manganate (LiMn ₂ O ₄ ) powder of No. 1 and MCMB which is a mesophase-based spherical graphite as the negative electrode active material, the thickness of the negative electrode active material layer (active material coated portion) W4 (the current collector thickness is (Not included)) and a length of 354 cm to produce a battery. The Li / Mn ratio of this positive electrode active material was 0.52, and the manganese elution amount was 5.0%.

It should be noted that, when the manufactured electrode is wound,
The length of the negative electrode is 12 c longer than the length of the positive electrode so that the positive electrode does not protrude from the negative electrode in the winding direction at the innermost circumference of the winding and the positive electrode does not protrude from the negative electrode in the winding direction even at the outermost circumference.
m longer. Also, the width of the negative electrode active material application part W4 is 4 mm larger than the width of the positive electrode active material application part W2 so that the positive electrode active material application part does not protrude from the negative electrode active material application part even in the winding direction and the vertical direction. (The same applies to the following Examples and Comparative Examples.)

[0028]

[Table 1]

Example 2 As shown in Table 1, Example 2
In the positive electrode active material, lot No. The lithium manganate powder of No. 2 was used, MCMB was used as the negative electrode active material, and the thickness (excluding the thickness of the current collector) of the negative electrode active material layer (active material application portion) W4 was 79 μm and the length was 354 cm. A battery was manufactured. The Li / Mn ratio of this positive electrode active material was 0.52, and the manganese elution amount was 5.5%.

Example 3 As shown in Table 1, Example 3
In the positive electrode active material, lot No. The lithium manganate powder of No. 3 was used, MCMB was used as the negative electrode active material, and the thickness (excluding the thickness of the current collector) of the negative electrode active material layer (active material coated portion) W4 was 79 μm and the length was 354 cm. A battery was manufactured. The Li / Mn ratio of this positive electrode active material was 0.52, and the manganese elution amount was 6.9%.

(Embodiment 4) As shown in Table 1, Embodiment 4
In the positive electrode active material, lot No. The lithium manganate powder of No. 4 was used, MCMB was used as the negative electrode active material, and the thickness (not including the current collector thickness) of the negative electrode active material layer (active material coated portion) W4 was 79 μm and the length was 354 cm. A battery was manufactured. The Li / Mn ratio of this positive electrode active material was 0.52, and the manganese elution amount was 9.2%.

Example 5 As shown in Table 1, Example 5
In the positive electrode active material, lot No. The lithium manganate powder of No. 5 was used, MCMB was used as the negative electrode active material, and the thickness (excluding the thickness of the current collector) of the negative electrode active material layer (active material coated portion) W4 was 79 μm and the length was 354 cm. A battery was manufactured. The Li / Mn ratio of this positive electrode active material was 0.55, and the manganese elution amount was 7.0%.

(Embodiment 6) As shown in Table 1, Embodiment 6
In the positive electrode active material, lot No. The lithium manganate powder of No. 6 was used, MCMB was used as the negative electrode active material, and the thickness (excluding the thickness of the current collector) of the negative electrode active material layer (active material coated portion) W4 was 79 μm and the length was 354 cm. A battery was manufactured. The Li / Mn ratio of this positive electrode active material was 0.58, and the manganese elution amount was 7.1%.

(Embodiment 7) As shown in Table 1, the embodiment 7
In the positive electrode active material, lot No. The lithium manganate powder of No. 7 was used, MCMB was used as the negative electrode active material, and the thickness (excluding the thickness of the current collector) of the negative electrode active material layer (active material coated portion) W4 was 79 μm and the length was 354 cm. A battery was manufactured. The Li / Mn ratio of this positive electrode active material was 0.60, and the manganese elution amount was 7.1%.

Example 8 As shown in Table 1, Example 8
In the positive electrode active material, lot No. The lithium manganate powder of No. 8 was used, MCMB was used as the negative electrode active material, and the thickness (excluding the thickness of the current collector) of the negative electrode active material layer (active material coated portion) W4 was 79 μm and the length was 354 cm. A battery was manufactured. The Li / Mn ratio of this positive electrode active material was 0.61, and the manganese elution amount was 7.2%.

Example 9 As shown in Table 1, Example 9
In the positive electrode active material, lot No. 9, a negative electrode active material layer (active material coated portion) W4 having a thickness (not including the current collector thickness) of 79 μm and a length of amorphous carbon as the negative electrode active material. Was set to 354 cm to produce a battery. The Li / Mn ratio of this positive electrode active material was 0.52,
The manganese elution amount was 7.0%.

Example 10 As shown in Table 1, in Example 10, lot No. was used as the positive electrode active material. Using lithium manganate powder of No. 10, using amorphous carbon as the negative electrode active material,
A battery was manufactured with a negative electrode active material layer (active material coated portion) W4 having a thickness (not including the current collector thickness) of 79 μm and a length of 354 cm. The Li / Mn ratio of this positive electrode active material is 0.1.
52, the manganese elution amount was 7.4%.

Example 11 As shown in Table 1, in Example 11, lot No. was used as the positive electrode active material. Using lithium manganate powder of No. 11, using amorphous carbon as the negative electrode active material,
A battery was manufactured with a negative electrode active material layer (active material coated portion) W4 having a thickness (not including the current collector thickness) of 79 μm and a length of 354 cm. The Li / Mn ratio of this positive electrode active material is 0.1.
52, the manganese elution amount was 8.3%.

Example 12 As shown in Table 1, in Example 12, lot No. 1 was used as the positive electrode active material. 12 lithium manganate powder, using amorphous carbon as the negative electrode active material,
A battery was manufactured with a negative electrode active material layer (active material coated portion) W4 having a thickness (not including the current collector thickness) of 79 μm and a length of 354 cm. The Li / Mn ratio of this positive electrode active material is 0.1.
52, the manganese elution amount was 10.7%.

Example 13 As shown in Table 1, in Example 13, lot No. 1 was used as the positive electrode active material. 13, using lithium manganate powder, using amorphous carbon as the negative electrode active material,
A battery was manufactured with a negative electrode active material layer (active material coated portion) W4 having a thickness (not including the current collector thickness) of 79 μm and a length of 354 cm. The Li / Mn ratio of this positive electrode active material is 0.1.
55, the manganese elution amount was 7.5%.

Example 14 As shown in Table 1, in Example 14, lot No. 1 was used as the positive electrode active material. Using lithium manganate powder of No. 14, using amorphous carbon as the negative electrode active material,
A battery was manufactured with a negative electrode active material layer (active material coated portion) W4 having a thickness (not including the current collector thickness) of 79 μm and a length of 354 cm. The Li / Mn ratio of this positive electrode active material is 0.1.
58, the manganese elution amount was 7.6%.

Example 15 As shown in Table 1, in Example 15, lot No. was used as the positive electrode active material. Using lithium manganate powder of No. 15, using amorphous carbon as the negative electrode active material,
A battery was manufactured with a negative electrode active material layer (active material coated portion) W4 having a thickness (not including the current collector thickness) of 79 μm and a length of 354 cm. The Li / Mn ratio of this positive electrode active material is 0.1.
60, the manganese elution amount was 7.7%.

Example 16 As shown in Table 1, in Example 16, lot No. 1 was used as the positive electrode active material. Using lithium manganate powder of No. 16, using amorphous carbon as the negative electrode active material,
A battery was manufactured with a negative electrode active material layer (active material coated portion) W4 having a thickness (not including the current collector thickness) of 79 μm and a length of 354 cm. The Li / Mn ratio of this positive electrode active material is 0.1.
61, the manganese elution amount was 7.6%.

Comparative Example 1 As shown in Table 1, Comparative Example 1
In the positive electrode active material, lot No. Using lithium manganate (LiMn ₂ O ₄ ) powder of No. 31 and MCMB which is a mesophase-based spherical graphite as the negative electrode active material, the thickness of the negative electrode active material layer (active material coated portion) (including the thickness of the current collector) Absent.)
Was 79 μm and the length was 354 cm to produce a battery.
The Li / Mn ratio of this positive electrode active material was 0.58, and the manganese elution amount was 4.7%.

Comparative Example 2 As shown in Table 1, Comparative Example 2
In the positive electrode active material, lot No. Using lithium manganate powder of No. 32 and MCMB as the negative electrode active material, the thickness of the negative electrode active material layer (active material coated portion) was 79 μm, and the length was 354 cm. Was prepared. The Li / Mn ratio of this positive electrode active material was 0.58, and the manganese elution amount was 3.8%.

Comparative Example 3 As shown in Table 1, Comparative Example 3
In the positive electrode active material, lot No. Using lithium manganate powder of No. 33, MCMB as the negative electrode active material, the thickness of the negative electrode active material layer (active material coated portion) is 79 μm, and the length is 354 cm. Was prepared. The Li / Mn ratio of this positive electrode active material was 0.58, and the manganese elution amount was 6.6%.

Comparative Example 4 As shown in Table 1, Comparative Example 4
In the positive electrode active material, lot No. Using lithium manganate powder of No. 34, MCMB as the negative electrode active material, the thickness (excluding the thickness of the current collector) of the negative electrode active material layer (active material coated portion) was 79 μm, and the length was 354 cm. Was prepared. The Li / Mn ratio of this positive electrode active material was 0.58, and the manganese elution amount was 4.5%.

<Test / Evaluation> Next, the following series of tests were performed on the batteries of the examples and the comparative examples thus manufactured.

The batteries of Examples and Comparative Examples were charged and then discharged, and the discharge capacities were measured. The charging conditions were a constant voltage of 4.2 V, a limited current of 5 A, and 3.5 hours. The discharge conditions are
The constant current was 5 A, and the final voltage was 2.7 V.

The discharge output of the battery in the charged state under the above conditions was measured. The measurement conditions were as follows: the voltage at the 5th second was read at each discharge current of 1A, 3A, and 6A, plotted on the vertical axis against the horizontal axis current value, and the approximate line connecting the three points intersected 2.7 V And the product of the current value of 2.7 V and 2.7 V was used as the output.

Further, after repeating charging and discharging 100 times under the above-mentioned conditions, the capacities of the batteries of the examples and the comparative examples were measured, and the retention ratio to the initial output was shown as a percentage. Naturally, the higher the maintenance ratio, the better the life characteristics.

The test results are shown in Table 2 below. The charge / discharge, capacity, and output measurements were all performed at an environmental temperature of 25 ± 1.
Performed in an atmosphere of ° C.

[0053]

[Table 2]

As shown in Table 2, in the batteries of Examples 1 to 16, high-capacity, high-output batteries were obtained, and the capacities and outputs after repeating charge / discharge 100 times were also kept high. . On the other hand, the batteries of Comparative Examples 1 and 2 in which graphite was used as the negative electrode and the manganese elution amount of lithium manganate as the positive electrode active material was less than 5%, and the amorphous carbon was used as the negative electrode, In the batteries of Comparative Example 3 and Comparative Example 4 in which the manganese elution amount of lithium manganate was less than 7%, a high-capacity, high-output battery was obtained, but the output was maintained after repeating charging and discharging 100 times. It can be seen that the rate has decreased.

When the Li / Mn ratio of lithium manganate is
In the batteries of Examples 5 to 7 and 13 to 15, which are 0.55 or more, the capacity retention ratio is extremely high. However, in the batteries of Example 8 and Example 16 exceeding 0.60, the result was accompanied by a remarkable decrease in capacity, and the Li / Mn ratio was 0.55 to 0.55.
It turns out that the range of 0.60 is preferable.

In particular, in the batteries of Examples 9 to 16 in which amorphous carbon was used for the negative electrode, a high output and a high output retention ratio were obtained. Therefore, it can be said that the batteries of Examples 9 to 16 are high-capacity, high-output, and excellent in life characteristics, and excellent in overall balance. In particular, using amorphous carbon as the negative electrode active material, the Li / Mn ratio is 0.55 to 0.55.
Example 13 in which the manganese elution amount was 0.60 or more and 7.5% or more
Batteries Nos. To 15 have the highest capacity retention ratio of 96% or more after repeating charging and discharging 100 times, and can be said to be batteries having more excellent life characteristics.

As described above, the cylindrical lithium ion battery 20 of the present embodiment is a battery having excellent initial capacity, initial output, capacity retention rate, and output retention rate. in this way,
A battery having a high capacity, a high output, and a high capacity retention rate and a high power retention rate is particularly suitable for a power source of an electric vehicle.

In the present embodiment, a large secondary battery used as a power source for an electric vehicle has been described as an example. However, the size and capacity of the battery are not limited, and the battery capacity is approximately 3 to 10 Ah. It has been confirmed that the present invention exerts remarkable effects on batteries. Further, in the present embodiment, the cylindrical battery is exemplified, but the present invention is not limited to the shape of the battery, and is applicable to a square battery and other polygon batteries. Furthermore, as a shape to which the present invention can be applied, a battery other than the battery having a structure in which the battery upper lid is sealed in the above-described bottomed cylindrical container (can) by caulking may be used. An example of such a structure is a battery in which the positive and negative external terminals penetrate the battery cover and the positive and negative external terminals press against each other via the shaft core in the battery container.

Further, in this embodiment, an example is shown in which an adhesive tape is used in which an insulating coating is made of polyimide as a base material and an adhesive made of hexamethacrylate is applied to one surface of the base material. Or a polyolefin such as polyethylene, an adhesive tape coated with an acrylic adhesive such as hexamethacrylate or butyl acrylate on one or both sides thereof, or a tape made of a polyolefin or polyimide not coated with an adhesive can also be suitably used. it can.

Further, in this embodiment, lithium manganate is used for the positive electrode for lithium ion batteries, amorphous carbon is used for the negative electrode,
The electrolyte used was one in which lithium hexafluorophosphate was dissolved at 1 mol / l in a mixed solution of ethylene carbonate, dimethyl carbonate and diethyl carbonate in a volume ratio of 1: 1: 1. There are no restrictions,
In addition, any of commonly used conductive materials and binders can be used. In general, lithium manganate can be synthesized by mixing and baking an appropriate lithium salt and manganese oxide. However, by controlling the charging ratio of the lithium salt and manganese oxide, desired Li / Mn can be obtained.
It can be a ratio.

The electrode active material binder for lithium ion batteries that can be used in other than this embodiment includes Teflon (registered trademark), polyethylene, polystyrene, polybutadiene, butyl rubber, nitrile rubber, styrene /
Examples thereof include butadiene rubber, polysulfide rubber, nitrocellulose, cyanoethylcellulose, various latexes, polymers such as acrylonitrile, vinyl fluoride, vinylidene fluoride, propylene fluoride, and chloroprene, and mixtures thereof.

Further, the positive electrode active material for lithium ion batteries that can be used in other than this embodiment is a material into which lithium can be inserted and desorbed, and a lithium manganese double oxide into which a sufficient amount of lithium has been inserted in advance. It is preferable to use lithium manganate having a spinel structure, or a material in which a part of manganese or lithium in the crystal is substituted or doped with another element.

Furthermore, the negative electrode active material for a lithium ion battery that can be used in other than this embodiment is not particularly limited except for the matters described in the claims. For example, natural graphite, artificial graphite materials, coke, carbonaceous materials such as amorphous carbon and the like may be used, and even in the particle shape thereof, flakes, spheres, fibers, lump, and the like are not particularly limited. Absent.

As the non-aqueous electrolytic solution, an electrolytic solution obtained by dissolving a general lithium salt as an electrolyte in an organic solvent is used. However, the lithium salt or organic solvent used is not particularly limited. For example, as the electrolyte, Li
ClO ₄ , LiAsF ₆ , LiPF ₆ , LiBF ₄ , LiB
(C ₆ H ₅ ) ₄ , CH ₃ SO ₃ Li, CF ₃ SO ₃ Li, and the like, and a mixture thereof can be used. Non-aqueous electrolyte organic solvents include propylene carbonate, ethylene carbonate, 1,2-dimethoxyethane, 1,2-diethoxyethane, γ-butyrolactone, tetrahydrofuran,
1,3-dioxolane, 4-methyl-1,3-dioxolane, diethyl ether, sulfolane, methylsulfolane, acetonitrile, propionitonyl, etc. or a mixed solvent of two or more of these may be used, and the mixing ratio is also limited. It is not something to be done.

[0065]

As described above, according to the present invention,
Since lithium-manganese double oxide is used for the positive electrode active material and graphite or amorphous carbon is used for the negative electrode active material, a high capacity, high output non-aqueous electrolyte secondary battery can be obtained, and graphite is used for the negative electrode active material. When lithium is used as the positive electrode active material, the amount of manganese eluted into the nonaqueous electrolyte is 5% or more based on the lithium manganese double oxide in a region where the electrode potential with respect to metallic lithium is 4.8 V or more. Using oxide,
Alternatively, when amorphous carbon is used as the negative electrode active material, the amount of manganese eluted into the nonaqueous electrolyte in the region where the electrode potential with respect to metallic lithium is 4.8 V or more is used as the positive electrode active material. Since a lithium manganese double oxide of 7% or more is used on the basis of the above, an effect that a nonaqueous electrolyte secondary battery having a high output maintenance ratio can be realized can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view of a cylindrical lithium ion battery according to an embodiment to which the present invention can be applied.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Shaft core 2 Positive electrode lead piece (part of positive electrode) 3 Negative electrode lead piece (part of negative electrode) 4 Positive electrode current collecting ring (part of connection part) 5 Negative electrode current collecting ring (part of connection part) 6 Winding Group (electrode group) 7 Battery container 8 Negative electrode lead plate (part of connection part) 9 Positive electrode lead (part of connection part) 10 Gasket 11 Cleavage valve 12 Lid case 13 Lid cap 14 Valve holder 20 Cylindrical lithium ion battery ( Non-aqueous electrolyte secondary battery) W1 Positive electrode current collector W2 Positive electrode active material layer W3 Negative electrode current collector W4 Negative electrode active material layer W5 Separator

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Yoshimasa Koishikawa 2-8-7 Nihonbashi Honcho, Chuo-ku, Tokyo Inside Shin-Kobe Electric Co., Ltd. (72) Kensuke Hironaka 2-87 Nihonbashi Honcho, Chuo-ku, Tokyo No.Shin Kobe Electric Co., Ltd.

Claims (4)

[Claims] 1. A battery container, comprising: an electrode group having a positive electrode, a negative electrode, and a separator; a connection portion for connecting the electrode group to each electrode terminal; and a non-aqueous electrolytic solution. In a non-aqueous electrolyte secondary battery using a positive electrode coated with an active material mixture containing both sides of a foil-shaped current collector,
In the region where the electrode potential with respect to lithium metal is 4.8 V or more, the amount of manganese eluted into the non-aqueous electrolyte is 5% or more based on the lithium manganese double oxide. A non-aqueous electrolyte secondary battery characterized in that graphite capable of occluding and releasing lithium ions by charge and discharge is used as a negative electrode active material. 2. A battery container, comprising: an electrode group having a positive electrode, a negative electrode, and a separator; a connection portion for connecting the electrode group to each electrode terminal; and a non-aqueous electrolytic solution. In a non-aqueous electrolyte secondary battery using a positive electrode coated with an active material mixture containing both sides of a foil-shaped current collector,
In the region where the electrode potential with respect to metallic lithium is 4.8 V or more, the amount of manganese eluted into the nonaqueous electrolyte is 7% or more based on the lithium manganese double oxide. A non-aqueous electrolyte secondary battery using amorphous carbon capable of occluding and releasing lithium ions by charge and discharge as a negative electrode active material. 3. The method according to claim 1, wherein the lithium / manganese double oxide has a Li /
3. The non-aqueous electrolyte secondary battery according to claim 1, wherein a ratio of Mn is 0.55 or more and 0.6 or less. 4. An amorphous carbon is used as the negative electrode active material, and the amount of manganese eluted into the non-aqueous electrolyte of the lithium manganese double oxide is determined based on the lithium manganese double oxide. The non-aqueous electrolyte secondary battery according to claim 3, wherein the content is 5% or more.