JPH09161778A - Organic electrolyte secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase capacity, and improve a cycle characteristic by improving carbon to be used as a negative electrode active material. SOLUTION: In an organic electrolyte secondary battery using lithium- containing transition metal chalcogenide as an positive electrode active material, a mixture having the mixing ratio of graphitized carbon on which an average particle diameter is not less than 9μm and an inter-layer distance (d002 ) is not more than 3.38Å and the crystallite size Lc in the (c) axis direction is not less than 400Å and small particle diameter carbon on which an average particle diameter is 0.5μm to 2μm and an inter-layer distance (d002 ) is not less than 3.39Å and the crystallite size Lc in the (c) axis direction is not more than 250Å is 98:2 to 60:40 in the weight ratio, is used as a negative electrode active material, and adhesive strength of a negative electrode is set not less than 10g, and liquid absorptivity is set not less than 5%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic electrolyte secondary battery, and more particularly to improvement of a negative electrode active material thereof.

[0002]

2. Description of the Related Art An organic electrolyte secondary battery represented by a lithium secondary battery has a large discharge capacity, a high voltage, and a high energy density, and therefore, there are great expectations for its development.

In this organic electrolyte secondary battery, an organic electrolyte in which a lithium salt is dissolved in an organic solvent is used, and lithium or a lithium alloy is used as a negative electrode active material. When the substance is used, an internal short circuit is likely to occur, which causes deterioration of battery characteristics and has a problem in safety.

Therefore, the use of a carbon material such as activated carbon or graphite as a negative electrode active material in place of lithium or a lithium alloy has been studied in JP-A-6-84515.

In Japanese Patent Laid-Open No. 6-84515, it is proposed that coke is added to graphite to improve cycle characteristics. However, the coke to be added has a smaller discharge capacity than graphite, and Since 40% by weight or more is added, the discharge capacity is remarkably reduced as compared with the case where only graphite is used.

[0006]

DISCLOSURE OF THE INVENTION The present invention solves the problems in the conventional organic electrolyte secondary battery as described above,
An object is to provide an organic electrolyte secondary battery having a large capacity and excellent cycle characteristics.

[0007]

As a result of intensive studies to achieve the above object, the present inventors have found that when a carbon mixture having the following characteristics is used as a negative electrode active material, it has a large capacity and a cycle: The inventors have found that an organic electrolyte secondary battery having excellent characteristics can be obtained, and have completed the present invention.

That is, the present invention relates to an organic electrolyte secondary battery having a positive electrode, a negative electrode, and an organic electrolytic solution using a lithium-containing transition metal chalcogenide as a positive electrode active material, wherein the negative electrode active material has an average particle size of 9 μm or more and an interlayer Distance d ₀₀₂
Is 3.38Å or less, and the crystallite size Lc in the c-axis direction is 4
Graphitized carbon over 00Å and average particle size 0.5μm
˜2 μm, the interlayer distance d ₀₀₂ is 3.39Å or more, and the c-axis direction crystallite size Lc is 250 Å or less. The organic electrolytic solution secondary battery is characterized in that the negative electrode has an adhesive strength of 10 g or more and a liquid absorbency of 5% or more.

The process of the present invention will be described in detail as follows. Generally, the deterioration of cycle characteristics is considered to be caused by the adhesive strength and liquid absorption of the electrodes. When graphitized carbon is used as the negative electrode active material, since the graphitized carbon has high crystallinity, the interlayer distance changes by about 10% due to the entry and exit of lithium ions. Therefore, as the charging / discharging cycle progresses, the adhesive strength between the metal foil such as a copper foil, which is the current collector, and the negative electrode mixture layer containing the active material decreases. Then, the present inventors have found that when the adhesive strength becomes smaller than 10 g, the capacity decreases. Therefore, when small particle size carbon was added to graphitized carbon and used as the negative electrode active material, the volume change of the negative electrode due to the ingress and egress of lithium ions was alleviated as compared with the case of only graphitized carbon, and as a result, the adhesive strength of the negative electrode was improved. It was found that the deterioration of the cycle was suppressed and the cycle characteristics were improved.

Carbon having an average particle size of 0.5 μm to 2 μm is used as the above-mentioned small particle size carbon, because carbon having an average particle size within this range enhances the adhesive strength of the negative electrode and enhances the liquid absorbing property. The average particle size of the small particle size carbon is 0.5.
When it is smaller than μm, the specific surface area becomes large, so that the retention becomes large, and when the average particle size of the small particle size carbon becomes larger than 2 μm, the discharge capacity per volume of the negative electrode also decreases. The retention is the ratio of the difference (irreversible charge capacity) between the charge capacity and the discharge capacity generated in the first cycle to the discharge capacity.

The carbon having a small particle size is preferably a carbon having a low crystallinity because the graphitized carbon has a high crystallinity and has a self-lubricating property and thus has a low adhesive strength with the current collector. _{Expressed by the} distance d ₀₀₂ and the crystallite size Lc in the c-axis direction, the interlayer distance d is small carbon.
₀₀₂ is 3.39Å or more, and the crystallite size Lc in the c-axis direction
Is preferably 250 Å or less, particularly preferably an interlayer distance d ₀₀₂ of 3.50 Å or more and a crystallite size Lc in the c-axis direction of 50 Å or less. That is, when the interlayer distance d ₀₀₂ of the small particle size carbon is 3.39Å or more, c
When the crystallite size Lc in the axial direction is 250 Å or less, the adhesive strength between the current collector and the negative electrode mixture layer is increased,
Further, the liquid absorbing property of the negative electrode mixture layer becomes high. Usually, an interlayer distance d ₀₀₂ of about 4.0 Å and a crystallite size Lc in the c-axis direction of about 5 Å can be suitably used. In addition, in this specification, the negative electrode mixture usually means a substance including carbon as an active material and a binder, but may include other substances if necessary.
The adhesive strength of the negative electrode means the adhesive strength between the current collector and the negative electrode mixture layer.

The higher the adhesive strength is, the more convenient it is to prevent the negative electrode material mixture layer from peeling from the current collector, but if the adhesive strength is too high, the amount of the binder increases.
Therefore, the conductivity between the carbon and the current collector is reduced, and the charge / discharge capacity may be reduced, which may cause other problems. Therefore, it is usually preferably 10 g or more and about 50 g or less. .

In the present invention, the measurement of the adhesive strength is
The scratch test is performed using a sapphire needle having a tip radius of 50 μm. That is, the adhesive strength is evaluated from the scratch resistance value at the critical load, by determining the critical load at which peeling of the negative electrode mixture layer from the current collector starts from the change in the resistance curve.

On the other hand, regarding the liquid absorbing property, the present inventors have found that when the liquid absorbing property of the negative electrode mixture is lower than 5%, the electrolytic solution does not reach the respective carbon particles, so that the capacity becomes small. It was In addition, in this specification, the liquid absorption property of the negative electrode means the liquid absorption property of the negative electrode mixture because the current collector has no liquid absorption property.

Further, the larger the liquid absorbing property is, the more convenient it is in that the electrolytic solution is spread over the carbon particles. However, if the liquid absorbing property is made too large, the density of carbon in the negative electrode mixture is lowered. Then, the discharge capacity per volume may be reduced and other disadvantages may occur. Therefore, it is usually preferably 5% or more and up to about 30%.

In the present invention, the liquid absorption property is evaluated by the electrolyte solution absorption rate of the negative electrode mixture, and the liquid absorption property is measured as follows. Negative electrode (may have current collector) 40mm
Cut into × 30 mm, measure the weight (Wl), then 1
After being immersed in the electrolytic solution for a period of time, the weight (W2) is measured.
Then, the liquid absorbency is calculated by the following formula.

[0017]

The graphitized carbon will now be described in detail. Graphitized carbon has a high crystallinity and has a property that it can have a high capacity. And in the present invention,
This graphitized carbon having an average particle size of 9 μm or more is used because if the particle size of the graphitized carbon is too small, the charge / discharge capacity at room temperature may decrease. This is because it is necessary to use one of However, if the particle size of the graphitized carbon becomes too large, the volume density of the negative electrode may decrease, and the battery capacity may decrease. Therefore, the graphitized carbon having an average particle size of 9 to 20 μm is most suitable.

Further, in the present invention, regarding the graphitized carbon, it is necessary that the interlayer distance d ₀₀₂ is 3.38 Å or less and the crystallite size Lc in the c-axis direction is 400 Å or more. This is because when satisfying, a high crystal and a large capacity can be obtained, and normally, the interlayer distance d
_{002 up} to about 3.35 Å and c-axis crystallite size Lc up to about 2500 Å can be suitably used.

The weight ratio of the graphitized carbon and the small particle size carbon is 98: 2 to 60:40. When the amount of the small particle size carbon is less than the above range, the negative electrode is bonded. It is not possible to sufficiently achieve the purpose of improving the cycle characteristics by increasing the strength and liquid absorption, and when the amount of the small particle size carbon exceeds the above range, the specific surface area of the small particle size carbon is large, This is because the retention may increase.

In the present invention, examples of the positive electrode active material include lithium nickel oxide, lithium manganese oxide and lithium cobalt oxide (these are usually represented by LiNiO ₂ , LiMnO ₂ and LiCoO ₂ , respectively. Ratio of Li to Ni, ratio of Li to Mn, L
The ratio of i to Co is often deviated from the stoichiometric composition), and a lithium-containing transition metal chalcogenide is used alone or as a mixture of two or more kinds. However,
The positive electrode active material exists as the above compound when the battery is in a discharged state, and when the battery is in a charged state, it exists in a state in which lithium is released.

Then, the positive electrode contains, if necessary, a conductive auxiliary agent such as phosphorus (scaly) graphite, acetylene black or carbon black, and, for example, polyvinylidene fluoride or polytetrafluoroethylene. , A positive electrode mixture prepared by adding a binder such as ethylene propylene diene terpolymer is pressure-molded, or a solvent is further added to form a paste, which is formed into a metal foil (for example, aluminum foil, titanium foil, platinum foil, etc.). ) Is applied to a current collector made of, for example, and dried. However, the method for producing the positive electrode is not limited to the above-described example.

The negative electrode is a negative electrode active material composed of a mixture of the above-mentioned specific carbons (however, the negative electrode active material exists as carbon itself when the battery is in a discharged state and when the battery is in a charged state. In the state where lithium ions are intercalated between the layers), a binder such as polyvinylidene fluoride, polytetrafluoroethylene, or ethylene propylene diene terpolymer is appropriately added to the negative electrode mixture prepared as necessary. Prepared through the process of pressure-molding the agent or adding a solvent to make a paste, applying the paste on a collector made of metal foil (for example, copper foil, nickel foil, etc.), and drying. To be done. However, the method for producing the negative electrode is not limited to the above-exemplified method.

An organic electrolytic solution (hereinafter, simply referred to as “electrolytic solution” unless otherwise indicated as a battery) is prepared by dissolving an electrolyte in an organic solvent. The organic solvent used in this case is a dielectric. It is preferable to use an ester having a high ratio or an ether or an ester having a low viscosity.

Examples of the ester having a high dielectric constant include propylene carbonate (PC), ethylene carbonate (EC), butylene carbonate (BC) and gamma-.
Butyrolactone (γ-BL) and the like can be mentioned.

Examples of low viscosity ethers include 1,2-dimethoxyethane (DME), dioxolane (DO), tetrahydrofuran (THF), 2-methyl-tetrahydrofuran (2Me-THF), diethyl ether (DEE) and the like. To be Examples of low-viscosity esters include methyl ethyl carbonate (MEC) and diethyl carbonate (DEC).

In addition, imide-based organic solvents, sulfur-containing or fluorine-containing organic solvents, trialkyl phosphates, etc. can also be used.

The electrolyte of the electrolytic solution is, for example, LiC.
10 ₄ , LiPF ₆ , LiBF ₄ , LiAsF ₆ , Li
SbF ₆ , LiCF ₃ SO ₃ , LiCF ₃ CO ₂ , Li
₂ C ₂ F ₄ (SO ₃ ) ₂ , LiN (CF ₃ SO ₂ ) ₂ ,
_{LiC (CF 3 SO 2) 3} , LiC n F 2n + 1 SO 3 (n
> = 2) and the like are used alone or in combination of two or more. In particular, LiPF ₆ , LiC ₄ F ₉ SO _{3 and the} like are preferable because they have good charge and discharge characteristics.

The concentration of the electrolyte in the electrolytic solution is not particularly limited, but is usually 0.01 to 5 mol /
1, especially about 0.05 to 2 mol / l is preferable.

[0030]

BEST MODE FOR CARRYING OUT THE INVENTION Next, the present invention will be described more specifically with reference to Examples. However, the present invention is not limited to only these examples.

Example 1 As graphitized carbon, bulk carbon obtained by heat-treating carbon microbeads extracted from petroleum pitch at 3000 ° C. was pulverized to prepare a powder having an average particle size of 10 μm. The interlayer distance d ₀₀₂ of this graphitized carbon is 3.36Å
The crystallite size Lc in the c-axis direction was 1000 Å or more. Also, as the small particle size carbon, coke is 120
What was heat-treated at 0 ° C. was pulverized to prepare a powder having an average particle size of 0.5 μm. Interlayer distance d ₀₀₂ of this small particle size carbon
Is 3.43Å, and the crystallite size Lc in the c-axis direction is 32Å
Met.

A carbon mixture 9 obtained by mixing these graphitized carbons and small particle size carbons in a weight ratio of 95: 5
10 parts by weight of polyvinylidene fluoride as a binder and 150 parts by weight of N-methyl-2-pyrrolidone as a solvent were mixed with 0 parts by weight to prepare a carbon paste, and the carbon paste was used as a copper foil as a current collector. After being coated on the above and dried, it was pressed with a calendar roll to prepare a carbon electrode used as a negative electrode. In the preparation of the above carbon paste, polyvinylidene fluoride was previously dissolved in N-methyl-2-pyrrolidone.

When the adhesive strength and liquid absorbency of this negative electrode were measured by the above-mentioned methods, the adhesive strength was 21 g and the liquid absorbency was 15%.

On the other hand, the positive electrode was manufactured as follows. That is, as the positive electrode active material, lithium nickel oxide (usually expressed as LiNiO ₂ , but the ratio of Li and Ni is slightly deviated from the stoichiometric composition) was used, and this lithium nickel oxide and phosphorous graphite were used. An active material-containing paste for forming a positive electrode containing polyvinylidene fluoride in the following ratio was prepared. Lithium nickel oxide 91 parts by weight Phosphorous graphite 6 parts by weight Polyvinylidene fluoride 3 parts by weight

To prepare the above-mentioned paste containing the active material for forming the positive electrode, polyvinylidene fluoride is dissolved in N-methyl-2-methylpyrrolidone in advance, lithium nickel oxide and phosphorous graphite are added and mixed, and This was done by adding N-methylpyrrolidone and mixing.

The obtained active material-containing paste for forming a positive electrode was applied onto an aluminum foil having a thickness of 20 μm using an applicator, dried and then pressed with a calendar roll to produce a positive electrode.

As the electrolytic solution, a solution obtained by dissolving 1 mol / liter of LiPF _{6 in} a mixed solvent of ethylene carbonate and 1,2-dimethoxyethane in a volume ratio of 1: 1 was used. , Outline 20mm, height 5m
A m-type button-type organic electrolyte secondary battery was produced.

In FIG. 1, 1 is a positive electrode mixture layer, 2 is a negative electrode mixture layer, 3 is a separator made of a microporous polypropylene film, and 4 is an electrolyte solution absorber made of polypropylene nonwoven fabric. 5 is a positive electrode can made of stainless steel, 6 is a positive electrode current collector made of aluminum foil, and 7
Is a negative electrode can made of stainless steel and having a nickel-plated surface. Reference numeral 8 is a negative electrode current collector made of copper foil, and 9 is a polypropylene annular gasket. In this battery, 1 LiPF ₆ is mixed in a mixed solvent of ethylene carbonate and methyl ethyl carbonate at a volume ratio of 1: 1. Mol / l dissolved electrolyte is injected.

Example 2 As a small particle size carbon, coke heat-treated at 1200 ° C. was pulverized to prepare a powder having an average particle size of 2.0 μm. The interlayer distance d ₀₀₂ of this small particle size carbon is 3.34Å
The crystallite size Lc in the c-axis direction was 32Å, which was the same value as that used in Example 1. And, except that this small particle size carbon is used and the weight ratio of the graphitized carbon and the small particle size carbon is set to 60:40,
A button type organic electrolyte secondary battery was produced in the same manner as in Example 1. The graphitized carbon was the same as in Example 1, and the adhesive strength of the obtained negative electrode was 19 g and the liquid absorption was 15%.

Example 3 As a small particle size carbon, a phenol resin heat-treated at 700 ° C. was pulverized to prepare a powder having an average particle size of 0.5 μm. The interlayer distance d ₀₀₂ of this small particle size carbon is 3.6.
The crystallite size Lc in the c-axis direction was 16Å at 1Å. Then, a button type organic electrolyte secondary battery was produced in the same manner as in Example 1 except that this small particle diameter carbon was used. The graphitized carbon was the same as that in Example 1, and the mixing ratio of the graphitized carbon and the small particle size carbon was 95: 5 in weight ratio as in Example 1. And
The obtained negative electrode had an adhesive strength of 20 g and a liquid absorbency of 16%.

Example 4 As a small particle size carbon, coke heat-treated at 1900 ° C. was crushed to prepare a powder having an average particle size of 0.5 μm. The interlayer distance d ₀₀₂ of this small particle size carbon is 3.39Å
The crystallite size Lc in the c-axis direction was 110Å.
And, using this small particle size carbon, the mixing ratio of graphitized carbon and small particle size carbon is 80: 2 by weight ratio.
A button type organic electrolyte secondary battery was produced in the same manner as in Example 1 except that the value was 0. The graphitized carbon was the same as in Example 1, and the adhesive strength of the obtained negative electrode was 1
At 2 g, the liquid absorption was 17%.

Example 5 As the graphitized carbon, natural graphite was crushed to obtain an average particle size of 1
7 μm powder was prepared. The interlayer distance d ₀₀₂ of this graphitized carbon is 3.35Å, and the crystallite size Lc in the c-axis direction is Lc.
Was 1000 ° or more. Then, a button type organic electrolyte secondary battery was produced in the same manner as in Example 1 except that this graphitized carbon was used. The small particle size carbon is the same as in Example 1, and the mixing ratio of the graphitized carbon and the small particle size carbon is 95: 5 in weight ratio as in Example 1.
Met. And the adhesive strength of the obtained negative electrode is 13 g.
The liquid absorbency was 15%.

Comparative Example 1 A button type organic electrolyte secondary battery was prepared in the same manner as in Example 1 except that the small particle size carbon was not used and the amount of graphitized carbon was increased accordingly. The negative electrode thus obtained had an adhesive strength of 10 g and a liquid absorbing property of 3%.

Comparative Example 2 As the small particle size carbon, coke heat-treated at 1200 ° C. was crushed to prepare a powder having an average particle size of 0.4 μm. This small particle size carbon has the same interlayer distance d ₀₀₂ and crystallite size Lc in the c-axis direction as in Example 1,
The average particle size is smaller than the range of 0.5 μm to 2 μm specified in the present invention. Then, a button type organic electrolyte secondary battery was produced in the same manner as in Example 1 except that this small particle diameter carbon was used. The obtained negative electrode had an adhesive strength of 8 g,
The liquid absorbency was 6%.

Comparative Example 3 As a small particle size carbon, coke heat-treated at 1200 ° C. was pulverized to prepare a powder having an average particle size of 3.0 μm. The interlayer distance d ₀₀₂ of this small particle size carbon and the crystallite size Lc in the c-axis direction are the same values as in Example 1, but the average particle size is larger than the range of 0.5 μm to 2 μm specified in the present invention. Then, a button type organic electrolyte secondary battery was produced in the same manner as in Example 1 except that this small particle diameter carbon was used. The obtained negative electrode had an adhesive strength of 5 g,
The liquid absorbency was 6%.

Comparative Example 4 As the small particle size carbon, natural graphite was crushed to prepare a crushed particle having an average particle size of 0.5 μm. The interlayer distance d ₀₀₂ of this small particle diameter carbon was 3.35Å, and the crystallite size Lc in the c-axis direction was 1000Å or more. That is, in this small particle size carbon, the interlayer distance d ₀₀₂ is 3.39 which is defined in the present invention.
It was smaller than the range above Å and had high crystallinity. Then, a button type organic electrolyte secondary battery was produced in the same manner as in Example 1 except that this small particle diameter carbon was used. The negative electrode thus obtained had an adhesive strength of 8 g and a liquid absorbing property of 3%.

Comparative Example 5 As small particle size carbon, coke heat-treated at 2400 ° C. was pulverized to prepare a powder having an average particle size of 0.5 μm. The interlayer distance d ₀₀₂ of this small particle size carbon is 3.41Å
Then, the crystallite size Lc in the c-axis direction is 260 Å or more, and the crystallite size Lc in the c-axis direction is defined by 2 in the present invention.
It was larger than the range of 50 Å or less. Then, a button type organic electrolyte secondary battery was produced in the same manner as in Example 1 except that this small particle diameter carbon was used. The obtained negative electrode had an adhesive strength of 7 g and a liquid absorbency of 4%.

Comparative Example 6 As the graphitized carbon, bulk carbon obtained by heat-treating carbon microbeads extracted from petroleum pitch at 3000 ° C. was crushed to prepare a crushed powder having an average particle size of 6 μm. In this graphitized carbon, the interlayer distance d ₀₀₂ and the crystallite size Lc in the c-axis direction are the same values as in Example 1, but the average particle size is smaller than the range of 9 μm or more specified in the present invention. Then, a button type organic electrolyte secondary battery was produced in the same manner as in Example 1 except that this graphitized carbon was used. The negative electrode thus obtained had an adhesive strength of 5 g and a liquid absorbing property of 5%.

Comparative Example 7 As the graphitized carbon, carbon microbeads extracted from petroleum pitch were heat-treated at 2400 ° C. and pulverized to prepare a powder having an average particle size of 0.5 μm. This graphitized carbon has an interlayer distance d ₀₀₂ of 3.41 Å and a crystallite size Lc in the c-axis direction of 260 Å, and the graphitized carbon has an average particle size smaller than the range of 9 μm or more specified in the present invention. , The interlayer distance d ₀₀₂ was larger than the range of 3.38 Å or more specified in the present invention, and the crystallite size Lc in the c-axis direction was smaller than the range of 400 Å or more specified in the present invention. Then, a button type organic electrolyte secondary battery was produced in the same manner as in Example 1 except that this graphitized carbon was used. The adhesive strength of the obtained negative electrode was 9
The liquid absorption was 6% and was 6%.

The batteries of Examples 1 to 5 and Comparative Examples 1 to 7 were charged and discharged with a current density of 0.5 mA / cm ² and a voltage of 10 mV.
The discharge capacity, retention, and the number of cycles until the discharge capacity decreased to 95% of the initial discharge capacity when charged and discharged at ˜1 V were examined. Table 1 shows the results. Table 1 also shows the adhesive strength and liquid absorbency of the negative electrode.

[0051]

[Table 1]

As is clear from the results shown in Table 1, in Examples 1 to 5, the discharge capacity was large, the number of cycles was large, and the cycle characteristics were excellent.

On the other hand, in Comparative Example 1, although the discharge capacity was large, the cycle characteristics were poor. This is considered to be because, in Comparative Example 1, only the graphitized carbon was used as the negative electrode active material, and thus the negative electrode had low adhesive strength and low liquid absorbency. Further, Comparative Example 2 also had poor cycle characteristics, and in particular, Comparative Example 2 had a large retention. It is considered that this is because the small particle size carbon used had a small average particle size and a large specific surface area. Then, in Comparative Example 3, a decrease in discharge capacity was recognized, and the cycle characteristics were poor. It is considered that this is because the average particle diameter of the small particle diameter carbon used was large.

In Comparative Examples 4 to 7, the cycle characteristics were poor, and some had very small discharge capacity and some had large retention. This is because the interlayer distance d ₀₀₂ of the small-sized carbon used is small and the crystallinity is high, or the crystallite size Lc of the small-sized carbon in the c-axis direction is
And the average particle size of the graphitized carbon are small, the interlayer distance d ₀₀₂ of the graphitized carbon is large and the crystallinity is low, and the crystallite size Lc in the c-axis direction is small. .

[0055]

As described above, according to the present invention, it is possible to provide an organic electrolyte secondary battery having a large capacity and excellent cycle characteristics.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an example of an organic electrolyte secondary battery according to the present invention.

[Explanation of symbols]

 1 Positive Electrode Mixture 2 Negative Electrode Mixture 3 Separator 4 Electrolyte Absorber

Claims (2)

[Claims] 1. In an organic electrolyte secondary battery having a positive electrode, a negative electrode, and an organic electrolytic solution using a lithium-containing transition metal chalcogenide as a positive electrode active material, the negative electrode active material has an average particle size of 9 μm or more and an interlayer distance d _002. 3.38Å or less, c
Graphitized carbon having an axial crystallite size Lc of 400 Å or more, an average particle size of 0.5 μm to 2 μm, and an interlayer distance d
₀₀₂ is 3.39Å or more, and the crystallite size Lc in the c-axis direction
Is a mixture having a small particle size of 250 Å or less and a weight ratio of 98: 2 to 60:40. 2. The organic electrolyte secondary battery according to claim 1, wherein the negative electrode has an adhesive strength of 10 g or more and a liquid absorbing property of 5% or more.