JP2003308880A - Method of manufacturing lithium secondary battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lithium secondary battery having improved reliability and a service life performance. <P>SOLUTION: A positive electrode active material layer containing as a main component a composite oxide represented by LiaNibCocMdO<SB>2</SB>, (where 0≤a≤1.1, 0.7≤b≤0.9, 0.1≤c≤0.3, 0≤d≤0.1, b+c+d=1, and M is at least one type of element selected from the group of Al, Mg, Ti, Mo, B, W, Nb) and a negative electrode active material layer capable of storing or releasing lithium ions are opposed to each other via a separator and impregnated with an organic electrolyte containing lithium ions. After a voltage of 4.0-4.3 V is applied between the positive electrode active material layer and the negative electrode active material layer at 45-60°C in such a voltage range that lithium is not deposited on a negative electrode, they are sealed into a battery case in a closed condition. <P>COPYRIGHT: (C)2004,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] The present invention relates to a lithium secondary battery.
It relates to a manufacturing method. [0002] 2. Description of the Related Art For example, a lithium transition metal is used as a positive electrode active material.
Composite oxide, carbonaceous material for negative electrode active material, lithium for electrolyte
Lithium using an organic electrolyte solution that uses a salt as a supporting salt
Rechargeable batteries have higher energy density compared to conventional batteries.
Degree, long life, for example, mobile phone, notebook type
It is used as a power source for devices. Such a Lichu
In a secondary battery, in particular, the positive electrode active material
Pressure, cycle life characteristics, safety, etc.
It is a key component. As a positive electrode active material of a lithium secondary battery,
A resource that uses inexpensive manganese with large reserves as a raw material
Active research has been conducted on titanium-manganese composite compounds.
ing. However, lithium manganese composite compounds
Low diffusion coefficient of lithium because it is an active material with
Heavy load characteristics and low temperature characteristics are not always sufficient
No. There is also a problem that the energy density is low. On the other hand, small lithium batteries currently on the market are
Secondary batteries have a layered structure of cobalt as the positive electrode active material.
Lithium oxide is often used. Lithium cobaltate
Is a spinel-structured active material with a lithium ion diffusion coefficient
It is extremely large, about 10 to 100 times the quality,
Despite its high degree, the raw material cobalt is a rare metal and the price is high
There is a problem of instability. [0005] Therefore, as a positive electrode active material, conventional Kobal
Inexpensive as compared to cobalt, and layered like cobalt
Lithium using nickel capable of forming a compound together with cobalt
Possible use of nickel-cobalt composite oxide
ing. However, lithium nickel cobalt
With composite oxides, conventional batteries can be used during initial charging or when left at high temperatures.
Because a large amount of gas is generated in comparison with
This will cause the internal resistance to increase, resulting in battery life
There is a problem that performance is reduced. [0007] SUMMARY OF THE INVENTION The present invention
It was completed based on circumstances, and
Reduces battery swelling during use, ensuring battery reliability and longevity
Aim to provide lithium secondary batteries with excellent life performance
It is assumed that. [0008] [MEANS FOR SOLVING THE PROBLEMS]
The method for manufacturing a lithium secondary battery according to claim 1,
ibCocMdO₂(However, 0 ≦ a ≦ 1.1, 0.7
≦ b ≦ 0.9, 0.1 ≦ c ≦ 0.3, 0 ≦ d ≦ 0.1,
b + c + d = 1, M = Al, Mg, Ti, Mo, B,
At least one element selected from the group consisting of W and Nb
Positive electrode active material layer containing a composite oxide represented by
And a negative electrode active material layer capable of inserting and extracting lithium ions.
With a lithium ion
After being impregnated with an organic electrolyte having a positive electrode active material layer and a negative electrode
4.0 to 4.3 V at 45 to 60 ° C. between the active material layers
Charge within the voltage range where lithium does not precipitate on the negative electrode
And then seal it tightly inside the battery container.
Have signs. In the present invention, LiaNibCocMdO is used.
₂The value a of the composite oxide represented by
If it is contained excessively, it becomes one or more. Also, after production
Since the absorption and release of lithium occur, the a value is eventually 0
It fluctuates in the range of 1.1. The value of b is 0.7 to 0.9.
Is preferred. If it is 0.7 or more, the conventional positive electrode active material
LiCoO used as₂Higher capacity than
Life is improved by setting it to 0.9 or less.
Because you do. Co is effective for structural stability of Ni-based active material
And the discharge capacity is reduced compared to other substitution elements.
Few. Maintain high structural stability and reduce costs
For this purpose, the c value should be mixed at a ratio of 0.1 to 0.3.
Is preferred. Further, LiaNibCocMdO₂In
A substitution element M represented by M (Al, Mg, Ti, Mo,
At least one selected from the group consisting of B, W, and Nb
Element) is more effective than Co mainly in structural stability.
However, the d value is 0 to 0.1 to reduce the discharge capacity.
It is preferable that In the present invention, first, the above-mentioned LiaNi
bCocMdO₂A composite oxide represented by
The positive electrode active material layer and the negative electrode active material layer are
Orientation and impregnated with organic electrolyte
4.0-4.3 V at 45-60 ° C. and negative
The battery is charged in a voltage range in which lithium is not deposited on the pole. this
By doing so, at the stage of manufacture,
Preliminary gas that may be generated from power generation elements during use
Most can be removed. When the battery temperature is over 60 ° C. and the battery voltage is
When the voltage is set to 4.3 V or more, the battery performance is significantly deteriorated. Ma
Also, charging at a battery temperature of less than 45 ° C and a voltage of less than 4.0V
Then, the gas generation speed becomes slow and the gas is released enough
May not be done. [0015] Such an operation is carried out outside the battery container or the battery.
After the operation inside the container, the power generation element
The battery is manufactured by sealing in a closed state. This
As described above, in a battery such as
Battery generation is greatly suppressed, and battery swelling extremely occurs.
This makes it harder to scrape and improves the battery life performance. Lithium nickel as the positive electrode active material of the present invention
Rucobalt composite oxide can be obtained by a known method, for example,
Carbonate, lithium nitrate, lithium oxide, lithium
Titanium hydroxide, nickel carbonate, nickel nitrate
Acid salts, nickel oxides, nickel hydroxides,
Carbonate, cobalt nitrate, cobalt oxide,
A hydroxide of cobalt and a metal element M as a raw material (M = A
1, Mg, Ti, Mo, B, W, Nb
At least one selected element)
Oxides, hydroxides, oxyhydroxides, chlorides, nitrates,
Sulfate, etc., are ground and mixed at a predetermined ratio to obtain an atmosphere containing oxygen.
For example, it can be obtained by firing at 600 to 900 ° C in the air.
Wear. In addition, instead of the compound containing the metal element M,
The genus M may be used. These are one kind alone
They may be used, or two or more kinds may be used as a mixture. The positive electrode is manufactured, for example, as follows.
Built. Use a graphite or carbon black
Together with a conductive agent such as rubber and a binder such as polyvinylidene fluoride
Mix to form a positive electrode mixture. Then, this positive electrode mixture is
-Disperse in a solvent such as methylpyrrolidone to form a slurry.
You. This can be, for example, aluminum, nickel, or stainless steel.
Coating and drying on both sides of a positive electrode current collector
The positive electrode is manufactured by compression smoothing with a gas or the like. The negative electrode active material is not particularly limited.
For example, known cokes, glassy carbons, graphs
Graphites, non-graphitizable carbons, pyrolytic carbons, carbon fiber
Such as carbonaceous materials, metallic lithium, and lithium
Gold, polyacene, or tin oxide glass, lithium
/ Titanium composite oxide, iron oxide, ruthenium oxide, oxidation
Molybdenum, tungsten oxide, titanium oxide, sulfur oxide
Or metal oxides such as silicon oxide alone or in combination of two or more
Can be used in combination,
Therefore, it is desirable to use a carbonaceous material. The negative electrode is manufactured, for example, as follows.
You. Use the negative electrode active material together with a binder such as polyvinylidene fluoride.
To form a negative electrode mixture. And this negative electrode mixture
Dispersed in a solvent such as N-methylpyrrolidone to form a slurry
I do. This is applied to both sides of the negative electrode current collector, dried, and rolled.
The negative electrode is manufactured by compression smoothing by a press or the like. The separator is not particularly limited.
For example, using a known woven fabric, nonwoven fabric, synthetic resin microporous membrane, or the like
In particular, a synthetic resin microporous membrane is preferably used.
Can be. Among them, polyethylene and polypropylene fine
Polyolefins such as porous membranes or composite microporous membranes
Thin microporous membrane is suitable in terms of thickness, membrane strength, membrane resistance, etc.
Used for The organic electrolyte of the present invention is not particularly limited.
Not possible, for example, ethylene carbonate and methyl ethyl carbonate
Mixed solvent with carbonate or ethylene carbonate
A mixed solvent with dimethyl carbonate is used. Mixing
Propylene carbonate, butylene carbonate
G, vinylene carbonate, trifluoropropylene carbonate
Carbonate, γ-butyrolactone, 2-methyl-γ-butane
Tyllactone, acetyl-γ-butyrolactone, γ-ba
Relolactone, sulfolane, 1,2-dimethoxy eta
1,2-diethoxyethane, tetrahydrofuran,
2-methyltetrahydrofuran, 3-methyl-1,3-
Dioxolan, methyl acetate, ethyl acetate, propionic acid
Methyl, ethyl propionate, dimethyl carbonate,
Diethyl carbonate, methyl ethyl carbonate, di
Propyl carbonate, methyl propyl carbonate,
Ethyl isopropyl carbonate, dibutyl carbonate
Or a mixture of two or more of these
You may. The electrolyte salt as a solute of the organic electrolyte is particularly
Not limited to, for example, LiClO₄, LiAsF₆, L
iPF₆, LiBF₄, LiCF₃SO₃, Li
CF₃CF₂SO₃, LiCF₃CF₂CF₂SO
₃, LiN (CF₃SO₂)₂, LiN (C₂F₅
SO₂)₂Used alone or in combination of two or more
can do. Among the electrolyte salts, LiPF
₆It is preferable to use Shape of lithium secondary battery obtained by the present invention
Has no particular restrictions. Sheet form (so-called film
Shape), foldable, wound cylindrical, wound square, coin
The shape and the like are selected according to the application. Hereinafter, examples of the present invention will be described.
It is not limited to this. Example 1 Examples 1-1 to 1-4, Comparative Examples 1-1 to 1
At -6, a lithium secondary battery was fabricated by the following method.
Was. First, as a positive electrode active material, 1 mol of lithium carbonate,
0.8 mol of nickel hydroxide and 0.5 mol of cobalt hydroxide
And 0.025 mol of aluminum sulfate.
Is calcined in air at a temperature of 750 ° C. for 15 hours.
Was. This product is LiNi_0.8Co_0.15Al
_0.05O₂It is inferred. This LiNi_0.8Co_0.15Al
_0.05O₂90 parts by weight and acetylene bra of conductive material
5 parts by weight and 5 parts by weight of polyvinylidene fluoride as a binder
And N-methyl-2-pyrrolidone as appropriate.
And dispersed to prepare a slurry. Add this slurry to 15
Thickness on both sides of aluminum positive electrode current collector of ~ 30 μm
After evenly applying and drying to a thickness of 60 μm,
A positive electrode was prepared by compression molding with a press. The negative electrode mixture was composed of 90 parts by weight of flaky graphite,
A mixture of 10 parts by weight of vinylidene refluoride and N-methyl
-2-Pyrrolidone is appropriately added and dispersed, and the slurry is prepared.
Made. This slurry is used to collect a 10 μm thick copper negative electrode.
After uniformly applying and drying on the body, compression
The negative electrode was produced by shaping. The separator has a microporous thickness of 25 μm.
A polyethylene film was used. As the organic electrolyte, ethylene carbonate is used.
(EC) and diethyl carbonate (DEC)
Mix at a ratio of 30:70 and add LiPF to this solution.₆To 1.2
The solution dissolved in mol / liter was used. The above positive electrode and negative electrode are interposed via a separator.
Wrap it facing each other, store it in the battery container,
An organic electrolyte was injected and impregnated. In Comparative Example 1-6,
After impregnation with the organic electrolyte, the battery container was hermetically sealed. (Example 1-1) The power generating element was
1 g per 1 g of positive electrode active material in a constant temperature bath at 45 ° C.
The battery is charged at a constant current of 4.1 mA at a current density of 50 mA,
After that, the battery was charged at a constant voltage of 4.1 V for 10 hours, and the battery container was removed.
The container was hermetically sealed to obtain a lithium secondary battery. (Example 1-2) The charging voltage was set to 4.3 V.
Lithium secondary battery under the same conditions as in Example 1-1 except that
I got Example 1-3 The charging temperature was set to 60 ° C.
Same conditions as in Example 1-1 except that the charging voltage was 4 V
Thus, a lithium secondary battery was obtained. Example 1-4 The charging temperature was set to 60 ° C.
Same as Example 1-1 except that the charging voltage was 4.3 V.
Under the conditions, a lithium secondary battery was obtained. (Comparative Example 1-1) The charging temperature was set to 40 ° C.
Same as Example 1-1 except that the charging voltage was 4.3 V.
Under the conditions, a lithium secondary battery was obtained. (Comparative Example 1-2) The charging temperature was set to 80 ° C.
Same conditions as in Example 1-1 except that the charging voltage was 4 V
Thus, a lithium secondary battery was obtained. (Comparative Example 1-3) The charging voltage was set to 4.5V.
Lithium secondary battery under the same conditions as in Example 1-1 except that
I got Comparative Example 1-4 The charging temperature was set to 60 ° C.
Same as Example 1-1 except that the charging voltage was 3.8 V
Under the conditions, a lithium secondary battery was obtained. (Comparative Example 1-5) The charging temperature was set to 60 ° C.
Same as Example 1-1 except that the charging voltage was 4.5 V
Under the conditions, a lithium secondary battery was obtained. (Comparative Example 1-6) The battery case was hermetically sealed.
After that, constant-current charging and charging were performed under the same conditions as in Example 1-1.
By performing constant voltage charging, a lithium secondary battery is obtained.
Was. Examples 1-1 to 1-4, Comparative Example 1-1
１−1-6 for the charge / discharge cycle test at 25 ° C.
Under the environment. Charging is 4.1V at a constant current of 1CmA
Up to 4.1V constant voltage for a total of 3 hours.
The operation was performed at a constant current of 1 CmA to a final voltage of 2.75 V. The results are shown below. [Table 1] As is clear from the above results, the charging temperature is
Within the range of 45 to 60 ° C. and the charging voltage is 4.0 to
Examples 1-1 to 1-4 in the range of 4.3 V
Have a high cycle life of 500 times or more,
There was no blister. On the other hand, the charging temperature was as low as 40 ° C.
In Example 1-1, the cycle life was reduced to 400 times, and
Swelling also occurred. This means that the gas can be
Is not released sufficiently. In addition,
In Comparative Example 1-2 in which the charging temperature was as high as 80 degrees,
The tool life was significantly reduced to 250 times. On the other hand, when the charging temperature is in the range of 45 to 60 ° C.
Even in the case of Comparative Example 1-3, the charging voltage was as high as 4.5 V,
Even so, the cycle life was significantly reduced to 200 times. Reverse
Meanwhile, in Comparative Example 1-4 in which the charging voltage was as low as 3.8 V,
Battery life is reduced to 350 times, and
Swelling occurred. Further, as in Comparative Example 1-5, precipitation of lithium
Battery or before charging as in Comparative Example 1-6.
If the cycle life is shortened even when the
In both cases, the battery swelled. [0046] Example 2 Examples 2-1 to 2-4 and Comparative Examples 2-1 and 2
At -6, a lithium secondary battery was fabricated by the following method.
Was. 1 mol of lithium carbonate and hydroxide
0.7 mol of nickel and 0.28 mol of cobalt hydroxide
And 0.01 mol of titanium sulfate and 0.01 mol of niobium hydroxide
And the mixture is heated in air at a temperature of 750 ° C.
For 15 hours. This product is LiNi_0.7C
o_0.28Ti_0.01Nb_0.01O₂Inferred
You. This LiNi_0.7Co_0.28Ti
_0.01Nb_0.01O₂And the same as in the first embodiment.
A positive electrode was prepared by the above method. In addition, the first embodiment and
Prepare the same negative electrode, separator and organic electrolyte, and
The battery is wound facing the negative electrode with a separator in between.
After being contained in the vessel, the organic electrolyte is injected through the injection hole to contain
Soaked. In Comparative Example 2-6, the organic electrolyte was impregnated.
Thereafter, the battery container was hermetically sealed. Then, the above Examples 1-1 to 1-4 and
Under the same conditions as in Comparative Examples 1-1 to 1-6, the lithium secondary
Ponds were obtained (Examples 2-1 to 2-4 and Comparative Examples 2-1 to 4-2).
2-6). Examples 2-1 to 2-4 and Comparative example 2-1
About 2-6 batteries were subjected to a charge / discharge cycle test at 25 ° C.
Under the environment. Charging is 4.1V at a constant current of 1CmA
Up to 4.1V constant voltage for a total of 3 hours.
The operation was performed at a constant current of 1 CmA to a final voltage of 2.75 V. The results are shown below. [Table 2] As is clear from the above results, the charging temperature is
Within the range of 45 to 60 ° C. and the charging voltage is 4.0 to
Examples 2-1 to 2-4 in the range of 4.3 V
Means that the cycle life is as high as 480 times or more,
There was no blister. On the other hand, the charging temperature was as low as 40 ° C.
In Example 2-1, the cycle life was reduced to 390 times,
Swelling also occurred. Comparative example in which the charging temperature is as high as 80 degrees.
In 2-2, the cycle life was extremely low at 260 times.
I dropped it. On the other hand, when the charging temperature is in the range of 45 to 60 ° C.
Even in the case of Comparative Example 2-3, the charging voltage was as high as 4.5 V,
Even so, the cycle life was significantly reduced to 210 times. Reverse
In Comparative Example 2-4 where the charging voltage was as low as 3.8 V,
The battery life is reduced to 370 times and the battery
Swelling occurred. Further, as shown in Comparative Example 2-5,
Out of the battery or before charging as in Comparative Example 2-6.
If the cycle life is shortened even when the
In both cases, the battery swelled. [0055] Example 3 Examples 3-1 to 3-4 and Comparative Examples 3-1 to 3-4
At -6, a lithium secondary battery was fabricated by the following method.
Was. 1 mol of lithium carbonate and hydroxide
0.7 mol of nickel and 0.28 mol of cobalt hydroxide
And 0.01 mol of molybdenum oxide and tungsten oxide
0.01 mol, and the mixture is heated in air at a temperature
It was baked at 850 ° C. for 15 hours. This product is LiNi
_0.7Co_0.28Mo _0.01W_0.01O₂Inferred
Is done. This LiNi_0.7Co_0.28Mo
_0.01W_0.01O₂And the same as in the first embodiment.
A positive electrode was prepared by the method. Moreover, the same as the first embodiment.
Prepare a negative electrode, separator and organic electrolyte like
The battery is wound with the electrodes facing each other with a separator
And then impregnated by injecting organic electrolyte through the injection hole
I let it. In Comparative Example 3-6, after impregnation with the organic electrolyte,
The battery container was hermetically sealed. The above Examples 1-1 to 1-4 and
Under the same conditions as in Comparative Examples 1-1 to 1-6, the lithium secondary
Ponds were obtained (Examples 3-1 to 3-4 and Comparative examples 3-1 to 3-1).
3-6). Examples 3-1 to 3-4 and Comparative example 3-1
The charge-discharge cycle test was performed at 25 ° C.
Under the environment. Charging is 4.1V at a constant current of 1CmA
Up to 4.1V constant voltage for a total of 3 hours.
The operation was performed at a constant current of 1 CmA to a final voltage of 2.75 V. The above results are shown below. [Table 3]As is clear from the above results, the charging temperature is
Within the range of 45 to 60 ° C. and the charging voltage is 4.0 to
Examples 3-1 to 3-4 in the range of 4.3 V
Have a high cycle life of 400 times or more,
There was no blister. In contrast, the charging temperature was as low as 40 ° C.
In Example 3-1, the cycle life was reduced to 380 times,
Swelling also occurred. Comparative example in which the charging temperature is as high as 80 degrees.
In 3-2, the cycle life was extremely low at 190 times.
I dropped it. On the other hand, when the charging temperature is in the range of 45 to 60 ° C.
Even in the case of Comparative Example 3-3, the charging voltage was as high as 4.5 V.
However, the cycle life was significantly reduced to 180 times. Reverse
In Comparative Example 3-4 where the charging voltage is as low as 3.8 V,
The battery life is reduced to 340 times and the battery
Swelling occurred. Further, as shown in Comparative Example 3-5,
Out of the battery or before charging as in Comparative Example 3-6.
If the cycle life is shortened even when the
In both cases, the battery swelled. From the above results, a high battery life is maintained.
To achieve this, the battery temperature must be between 45 and 60 ° C. and between 4.0 and 4.3 V.
Charge in a voltage range where lithium is not precipitated.
Is preferred. In this embodiment, the positive electrode active material and
And LiNi_0.8Co_0.15Al_0.05O₂, L
iNi_0.7Co_0.28Ti_0.01Nb_0.01O
₂, LiNi_0.7Co_0.28Mo_0.01W
_0.01O₂Was used, but for example, Li_1.05N
i_0.82Co_0.15Mg_0.03O₂General formula L
iaNibCocMdO_Two((However, 0 ≦ a ≦ 1.
1, 0.7 ≦ b ≦ 0.9, 0.1 ≦ c ≦ 0.3, 0 ≦ d
≦ 0.1, b + c + d = 1, M = Al, Mg, Ti, M
o, B, W, at least selected from the group consisting of Nb
The same effect can be obtained by using an active material represented by
It is clear that is obtained. [0066] The method of manufacturing a lithium secondary battery according to the present invention.
According to the method, battery swelling during use after battery manufacture
And a lithium secondary battery with excellent reliability and longevity
Can be

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Claims (1)

Claims 1. LiaNibCocMdO ₂ (provided that
0 ≦ a ≦ 1.1, 0.7 ≦ b ≦ 0.9, 0.1 ≦ c ≦
0.3, 0 ≦ d ≦ 0.1, b + c + d = 1, M = Al,
At least one element selected from the group consisting of Mg, Ti, Mo, B, W, and Nb), and a positive electrode active material layer containing a composite oxide as a main component, and capable of inserting and extracting lithium ions. The negative electrode active material layer is opposed to the negative electrode active material layer via a separator, and impregnated with an organic electrolyte solution containing lithium ions. A method for producing a lithium secondary battery, comprising charging the battery in a voltage range of from about 4.3 V to a level at which lithium does not deposit on the negative electrode, and then sealing the battery in a battery container.