JP3053370B2 - Method of evaluating carbon material for battery and method of manufacturing battery using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carbon material for a battery, and more particularly, to a contact heat (immersion heat) obtained by bringing a carbon material used mainly for a negative electrode of a lithium ion type battery into contact with various organic solvents. The present invention relates to a method for evaluating the electrode capacity characteristics of a carbon material based on the above, and a method for manufacturing a battery using the method.

[0002]

2. Description of the Related Art Conventionally, various carbon materials have been used as a negative electrode carbon material in a lithium ion type battery.
It is roughly classified into three types: non-graphitizable carbon materials that are not easily graphitized by about 3000 ° C.), graphitizable carbon that is easily graphitized, and graphite-based carbon that has already been graphitized before treatment. All of these carbons have a layered structure having a hexagonal network structure formed by carbon atoms, that is, a graphite structure, but the manner of stacking of the hexagonal network structure differs depending on the type of carbon, and more generally, It differs for each production lot.

In a lithium ion battery, lithium ions enter and exit between layers of the negative electrode carbon crystal, that is, between layers of a hexagonal network structure, during charging and discharging, so that the properties of the hexagonal network structure and the layered structure formed by the hexagonal network structure are increased. The difference is an important evaluation point of carbon materials. In fact, the evaluation of the negative electrode carbon material for a lithium ion battery has been performed based on the geometrical structure, that is, the physical structure of the carbon material. Specifically, the physical structure of the carbon material was investigated by X-ray diffraction and / or Raman spectroscopy, and the carbon material was evaluated based on the obtained data.

From the pattern and spread data of the diffraction line obtained by using the X-ray diffraction method, the degree of graphitization, the size of crystallites, the distance between planes of the hexagonal network structure, and the graphite Structure and the like can be evaluated. Here, the evaluation of the graphite structure means the distinction between the ABAB type and the ABC type, or the determination of the mixing ratio of those types. Among these physical properties,
The distance between the hexagonal mesh structures (mesh planes), which is an index of the interlayer distance, is regarded as important. For example, the value is 0.337 n using the surface distance d (002) in the C-axis direction of the graphite structure as an index.
m or less is recommended (Japanese Patent Laid-Open No. 6-2).
0721).

[0005] In the case of using the Raman spectroscopy, the intensity ratio of the spectral lines of the specific Raman scattered light are important, for example, the intensity ratio of 1360 cm ^-1 and 1580 cm ^-1 is 0.4 or more It is recommended that carbon materials be suitable (see JP-A-6-236754). Here, the scattered radiation at 1580 cm ^-1 corresponds to the natural vibration mode of the graphite structure, and
Since the scattered radiation at 0 cm ^-1 appears with the miniaturization of the graphite particles, the intensity ratio of the two Raman spectra is considered to be an index relating to the size of the graphite particles.

However, only the evaluation method based on the physical structure of the carbon material mainly using the X-ray diffraction method and / or Raman spectroscopy as described above selects and / or sorts the negative electrode carbon material for the lithium ion battery. In quality control for each production lot and in quality control of lithium-ion batteries manufactured using these carbon materials, it is difficult to say that a sufficiently reliable evaluation can be made. It must be made and its performance evaluated and sorted.

This is considered to be due to the following reasons. Lithium ions exist in a state surrounded by organic solvent molecules, that is, in a solvated state, in an electrolytic solution composed of an organic solvent and an inorganic salt. Therefore, when lithium ions enter between layers of the hexagonal network structure of the negative electrode carbon material in the negative electrode of the lithium ion type battery, it is necessary to undergo a chemical reaction for removing all or a part of the solvated organic solvent molecules on the carbon surface. .
The chemical properties of the carbon surface structure, such as the affinity between the carbon surface and the organic solvent, greatly affect the ease of occurrence of this chemical reaction. However, such a chemical property of the carbon surface cannot be evaluated by a conventional physical structure evaluation method.

In order to solve the above problems, the inventors of the present invention have determined the contact heat obtained by measuring the contact heat between the carbon material and various organic solvents and the values calculated therefrom, for example, the calorific value ratio and the adsorption surface area ratio. Based on the correlation between the chemical characteristics of the carbon material evaluated in advance based on, for example, and the electrode capacity characteristics of the carbon material previously investigated using a battery manufactured using the material, the carbon material and various organic solvents are used. (Japanese Patent Application No. Hei 7-231710) proposes a method and an apparatus for evaluating a carbon material for a battery, which judge the quality of electrode capacity characteristics of the carbon material based on the contact calorific value of the carbon material. It has become possible to evaluate a carbon material without manufacturing a battery based on the chemical properties of the above.

[0009]

However, in the chemical evaluation method proposed by the present inventors, if the carbon material to be evaluated is hardly graphitized carbon or graphite-based carbon, the same organic solvent is used. Although it can be evaluated by using the same, when it is graphitizable carbon, it is necessary to evaluate using a different kind of organic solvent. Therefore, an evaluation method capable of chemically evaluating a carbon material from another viewpoint,
In particular, the development of a simpler evaluation method regardless of the characteristics of the carbon material has been required. Further, development of a method capable of evaluating properties of a carbon material in more detail has been required.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and clarifies the chemical characteristics of a carbon material for a negative electrode of a lithium ion type battery. A method for evaluating battery carbon materials that can be chemically evaluated from a different point of view, which can evaluate characteristics as battery materials, especially a universal chemical evaluation method for battery carbon materials regardless of material characteristics The purpose is to provide. Another object of the present invention is to provide a method for manufacturing a battery, which is manufactured using the carbon material for a battery selected by the chemical evaluation method of the present invention.

[0011]

Means for Solving the Problems The present inventors have conducted intensive studies in view of the above-mentioned problems, and as a result, have measured and obtained the contact heat quantity (mJ / g) between a carbon material and various organic solvents. The contact calorific value (mJ / m ² ) is calculated from the contact calorific value per unit surface area (mJ / m ² ) and / or various values further obtained from the contact caloric value (mJ / m ² ), for example, a plurality of contact calorific values (mJ / m ^2). )
By converting to a value such as the product or ratio of the carbon material, it is possible to evaluate the chemical characteristics of the carbon material, and further, by measuring the electrode capacitance characteristics of the carbon material in a battery manufactured using the material, By examining the correlation between the characteristics and the electrode capacity, it is possible to obtain an index that can be used for evaluating the carbon material for a battery, and to measure the contact heat (mJ / g) between the carbon material and various organic solvents, and Various values obtained by converting the obtained contact heat amount (mJ / g) into the contact heat amount per unit area (mJ / m ² ), such as the product or ratio of a plurality of contact heat amounts (mJ / m ² ) By converting the value into a relative value with reference to a specific artificial graphite, it is possible to evaluate the chemical characteristics of the carbon material, and further measure the electrode capacity characteristics of the carbon material in a battery manufactured using the material, carbon By examining the correlation between the chemical characteristics of the material and the electrode capacity, it was found that an index that can be used for evaluating the carbon material for a battery was obtained, and the present invention was completed.

Thus, according to the present invention, the contact heat per unit area (mJ / m ² ) calculated by measuring the contact heat (mJ / g) between the carbon material and various organic solvents and / or A chemical characteristic of the carbon material evaluated in advance based on a calculated value obtained from the contact calorific value (mJ / m ² ), for example, a product or ratio of a plurality of contact calorific values (mJ / m ² ); Using the correlation between the electrode capacity of the carbon material and the electrode capacity of the carbon material previously investigated using as an index, determining whether the electrode capacity characteristic of the carbon material is good or bad based on the contact heat between the carbon material and various organic solvents, An evaluation method is provided.

Further, according to the present invention, a calculated value obtained from a contact heat per unit area (mJ / m ² ) calculated by measuring a contact heat (mJ / g) between a carbon material and various organic solvents. For example, a value of a ratio of a plurality of contact calories (mJ / m ² ) and the like are evaluated in advance based on a relative value obtained with reference to a specific artificial graphite, and a chemical characteristic of a carbon material is evaluated in advance using the material. Using the correlation between the electrode capacity of the carbon material as an index, determine the quality of the electrode capacity characteristics of the carbon material based on the contact heat between the carbon material and various organic solvents,
A method for evaluating a carbon material for a battery is provided.

Further, according to the present invention, there is provided a method for producing a lithium ion battery, characterized in that the method is produced using the carbon material evaluated and selected by the evaluation method of the present invention. In this specification, the term solvent is used.
It is used to include all compounds or mixtures of compounds in gaseous, liquid or solid state that react upon contact with carbon. In this specification and the accompanying drawings, the contact calorific value (mJ / g) obtained by converting the contact calorific value (mJ / g) between the carbon material and the organic solvent per unit area is shown.
m ² ) may be represented by ΔH (organic solvent name) such as ΔH (hexane).

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The method of the present invention is based on the following findings. The surface of a carbon material has various chemical properties due to various residual functional groups and the like for each type and production lot. Such chemical properties include:
The absolute amounts of the donor and acceptor moieties in hydrogen bonds and their ratios, and the area of the bottom of the graphite structure where the hexagonal network structure, which is considered to cause weak chemical bonding involving π electrons, appears, For example, the ratio to the area of the edge surface, which is considered to cause a relatively strong chemical bond due to the large number, can be mentioned. These properties determine the reactivity of the carbon material with various organic solvents. For example, a carbon material having a large number of hydrogen bond acceptor moieties is highly reactive with a certain type of organic solvent and generates a large amount of contact heat, but not so reactive with another organic solvent and generates contact heat. Not so much.

Therefore, it is considered that the difference in chemical properties of various carbon materials can be clarified by measuring the difference in contact heat generated when various carbon materials are brought into contact with various organic solvents. That is, whether or not a certain carbon material has desirable chemical properties as a battery negative electrode material is evaluated based on data obtained by measuring the amount of contact heat generated by bringing the carbon material into contact with an organic solvent. It is possible.

Further, a measured value obtained by actually fabricating an appropriate battery using the above-mentioned carbon material and measuring the electrode capacity characteristics of the negative electrode carbon material in the battery and the contact value between the carbon material and various organic solvents are described. To clarify the correlation between the calorific value (mJ / m ² ) and / or a value calculated from the contact calorific value (mJ / m ² ), for example, the product or ratio of a plurality of contact calorific values (mJ / m ² ) Thereby, an index suitable for evaluating the carbon material can be obtained. Further, a plurality of obtained index values can be combined to obtain a more accurate index. These indices can be expressed as absolute values for individual carbon materials, but are normalized using the values obtained for artificial graphite materials, which are carbon materials having a structure closest to the ideal graphite structure, and By calculating the relative ratio, it can be expressed as a relative value. Further, the characteristics of the test carbon material can be evaluated by combining a plurality of the relative values. At this time, for example, by preparing a chart such as a quadrupole diagram, the characteristics of a plurality of test materials can be easily compared and evaluated.

It is preferable to use a material having a graphite structure that is close to ideal, as a carbon material used as a standard for relatively expressing the characteristics of each carbon material. The present inventors' research has revealed that the surface layer is damaged during the pulverization process and has a structure different from the original crystal structure of graphite.
(October 995), since the properties of such a material are very similar to those of the non-graphitizable carbon material, which are different from the properties predicted from the graphite structure, Artificial graphite materials are preferred.
Examples of such artificial graphite include, for example, KS-6 (average particle diameter: 6 microns), which is an artificial graphite manufactured by Lonza. If necessary, other artificial graphites similar in chemical properties to the reference artificial graphite, for example, KS-
6, the graphite fine particles grown in a vapor phase at a relatively low temperature (hereinafter referred to as low-temperature-grown graphite fine particles or MS)
Sometimes referred to as G. ) Can be used to supplement the measured values of artificial graphite as a reference.

The organic solvent used for obtaining the index in the present invention has a melting point of 20 ° C. or lower and a boiling point of 50 ° C.
An organic solvent having a temperature of not lower than ℃ is preferable because of easy handling. Further, the type of organic solvent that can be used in the evaluation method of the present invention,
Although it is not particularly limited as long as it can react with carbon, a solvent generally used as an electrolyte solvent for a battery, for example, a linear hydrocarbon, a cyclic hydrocarbon, an aromatic hydrocarbon, an alcohol, Ketones, ethers, carbonates, sulfoxides, alkyl cyanides, pyridines and the like are preferably used.

Hexane (C ₆ H ₁₄ : boiling point 68 ° C.) can be exemplified as a preferable linear hydrocarbon used in the method of the present invention. If the boiling point of the straight-chain hydrocarbon is higher than room temperature, it is advantageous because it can be handled as a liquid at room temperature, but at a boiling point of about pentane (C ₅ H ₁₂ : 36 ° C.), a measurement error due to heat of vaporization occurs. A straight-chain hydrocarbon having a carbon number equal to or more than hexane is convenient for handling because it is easy to handle.

Further, as the number of carbon atoms in the linear hydrocarbon increases, the heat of contact with carbon increases (JHClinte;
Chem. Soc. Faraday Tr.1, vol.69 (1973), p.1320
Hexane (C ₇ H ₁₆ ) or higher is preferred, but hexane is most preferable because the liquid viscosity at room temperature is high and the ease of handling is somewhat inferior.

However, long-chain straight-chain hydrocarbons which are solid at room temperature by themselves and have a carbon number of about 28 to 36 can be dissolved in hexane, for example, dotriacontan (C ₃₂ H ₆₆ ) was dissolved in hexane at 2% by weight (hereinafter referred to as a 2% dotriacontane / hexane solution) and brought into contact with the carbon material to form a long linear carbonized hydrocarbon chain such as dotriacontane. Since the adsorption of hydrogen occurs prior to the adsorption of hexane and shows a behavior different from that of hexane alone, such a solution can also be suitably used in the evaluation method of the present invention.

The cyclic hydrocarbon used in the present invention includes:
Cyclic hydrocarbons having about 6 carbon atoms can be mentioned, and among them, the use of a cyclic hydrocarbon having a chair-shaped structure is convenient for evaluating a rough surface structure, and among those having such a structure, easy handling is possible. Cyclohexane (boiling point: 81 ° C.) can be suitably used.

The aromatic hydrocarbon used in the present invention is an aromatic hydrocarbon having about 6 carbon atoms, among which π-electrons and having substantially the same molecular structure as one of the hexagonal networks at the bottom of the graphite structure. Therefore, benzene (boiling point: 80 ° C.), which preferentially adsorbs on the bottom surface of the graphite structure, is preferable.

The above cyclohexane and benzene both have a higher boiling point than hexane, and they are the most basic compounds and have no substituents. It can be suitably used for the method of.

Pyridine, which is a six-membered heterocyclic compound exhibiting behavior similar to aromatics, also has a high donor number (W. Gutman; Electrochim., Vol . 21 (1976), p. 661).
Therefore, it is an organic solvent suitable for evaluating electron transfer reactivity.

By using normal butanol and tertiary butanol as alcohols used in the present invention, it is possible to evaluate the effect of the conformation, and these can be suitably used. Trifluoroethanol can also be suitably used in the present invention, but this compound is a perfect hydrogen bond donor (RWTaft et al.,
J. Solution Chem., Vol . 14 (1985), p. 153), which can be used to evaluate the hydrogen bond acceptor portion of carbon.

In the present invention, by using a ketone, ether or carbonate, an easily oxidizable portion existing on the carbon surface can be evaluated by utilizing an interaction between carbon contained in the molecule and carbon. Ketones, ethers or carbonates that can be used in the present invention include acetone (boiling point 56 ° C.); tetrahydrofuran (boiling point 66 ° C.), dipropyl ether (boiling point 90 ° C.), dibutyl ether (boiling point 142 ° C.); and propylene carbonate, respectively. (Boiling point: 242 ° C.), dimethyl carbonate (boiling point: 90 ° C.), methyl ethyl carbonate (boiling point: 107 ° C.), diethyl carbonate (boiling point: 126 ° C.), and the like. Among these, propylene carbonate, which is one of the main battery solvents and has a high boiling point and is easy to handle, can be suitably used.

Similarly, in the present invention, by using a sulfoxide and an alkyl cyanide, a portion acting as a cation on a carbon surface is evaluated by utilizing the nucleophilicity of a sulfonic acid group and a cyano group of the sulfoxide and the alkyl cyanide. Can be. Examples of the sulfoxide that can be used in the present invention include dimethyl sulfoxide (boiling point: 189 ° C.) and diethyl sulfoxide (boiling point: 90 ° C.), and alkyl cyanide includes acetonitrile (boiling point: 82 ° C.) and propiononitrile (boiling point: 97 ° C.) can do.

The measurement of the contact heat between the various organic solvents described above and the carbon to be evaluated can be performed as follows. First, a measuring container of a twin calorimeter equipped with a blade which can be operated from the outside is filled with an organic solvent, and the sealed carbon is immersed in a polyethylene bag and sealed therein. Then, the measurement container and the reference container are left at room temperature until they reach an isothermal state. After the two have reached the isothermal state, the cutting tool is operated from the outside to break the polyethylene bag containing carbon, thereby mixing the carbon with the organic solvent and measuring the generated contact heat.

At this time, if the contact heat is smaller than the heat of vaporization of the organic solvent, the airtightness of the measuring vessel greatly affects the accuracy of the contact heat measurement. Cost. In order to obtain sufficient airtightness, the lid of the measuring container is desirably a threaded seal having an O-ring seal. Further, it is desirable to select the type of the sealing material of the O-ring seal according to the type of the organic solvent to be used so that sufficient airtightness is always maintained.
Within the range of the following examples, good airtightness can be obtained by using an O-ring seal made of butyl rubber.

From the contact calorie (mJ / g) between the carbon material and various organic solvents measured as described above and the BET surface area (m ² / g) determined according to a conventional method, the contact calorie per unit area (mJ / g) / m ² ), and from the obtained contact heat (mJ / m ² ), it is possible to obtain various calculated values, for example, the sum, product or ratio of a plurality of contact heats (mJ / m ² ). it can.
These calculated values may be used alone or in combination of two or more as absolute values or converted into relative values based on an appropriate carbon material for evaluation of the present invention. Although the accuracy of estimating the characteristics can be increased to some extent by increasing the types of calculation values used for evaluation, evaluation is usually performed using about 1 to 5 types of values from the viewpoint of work efficiency and the like.

Further, by preparing an appropriate battery using the test carbon material according to a conventional method, the electrode performance can be investigated. By examining the correlation between various measured values and calculated values obtained in this way, it is possible to clarify the chemical characteristics of the carbon material and determine an index for evaluating the carbon material. Then, a carbon material suitable for manufacturing a battery having desired battery performance is selected based on the index, and a battery can be manufactured using the material.

However, as described above, carbon materials are roughly classified into three types based on the crystal structure. Therefore, when examining the evaluation index obtained by measuring the contact heat between the carbon material and various organic solvents, It is desirable to pay attention to the type of carbon material. The following examples illustrate the invention in more detail.

[0035]

【Example】

Embodiment 1 FIG. As the carbon material, the starting material (base agent / crosslinking agent) ratio and the processing temperature at the time of producing the carbon material are different.
6 types of non-graphitizable carbon, 6 types of easily graphitizable carbon (mesophase carbon microbeads) with different heat treatment conditions (oxygen concentration and processing time) during carbon material production, and natural graphite are crushed and classified according to particle size. 2
Different types of graphite-based carbon were used. These are all the same as the carbon materials used in the development of the carbon material evaluation method previously proposed by the present inventors (Japanese Patent Application No. 7-23).
No. 1710). As graphite-based carbon materials, four types of artificial graphites having different production conditions were also tested, and a total of six types of graphite-based carbon materials were used.

First, a test carbon material and hexane, benzene, pyridine, normal butanol, tertiary butanol, dimethyl sulfoxide, and a 2% dotriacontane / hexane solution (hereinafter abbreviated as dotriacontane) are used. The heat of contact with the various organic solvents was measured by the method described above using a twin calorimeter. After converting the measured contact calorie (mJ / g) into a contact calorie per unit area (mJ / m ² ) according to a conventional method, the index was used for examination of an index used for a carbon material evaluation method.

Next, a test battery was prepared using the test carbon material. Using 45 parts by weight of an NMP solution as a coating solvent, 5 parts by weight of PVDF as a binder was dissolved in the solution to form a binder solution.
The weight part was added to obtain a coating liquid for a negative electrode. The obtained negative electrode coating liquid was applied on a copper foil current collector having a thickness of 20 μm and dried to prepare a negative electrode sheet having a thickness of about 100 μm. Similarly, to 50 parts by weight of the binder solution, 45 parts by weight of lithium cobaltate and 5 parts by weight of graphite were added to prepare a coating solution for a positive electrode.
A positive electrode sheet having a thickness of about 100 μm was prepared by coating and drying on a micron aluminum foil current collector.

Then, lithium perchlorate was dissolved in a 1: 1 mixed solvent of ethylene carbonate and dimethoxyethane at a ratio of 1 mol / l to prepare an electrolyte. These materials and a 2025 cell (diameter 2 cm, thickness 2.5 m)
m) was used to produce a coin-type battery. Next, the discharge capacity of the manufactured battery was measured. At this time, the discharge capacity stably obtained after subjecting the battery to about 10 charge / discharge cycles was taken as the characteristic value of the test carbon material.

The relationship between the contact heat per unit area (mJ / m ² ) and the discharge capacity of the battery obtained as described above was examined in various ways. As a result, the contact heat per unit area (mJ / m
It was found that the following values 1) to 10) obtained from m ² ) can be used as indicators of the discharge capacity of the battery. 1) △ H (hexane) x △ H (tertiary butanol) 2) △ H (hexane) x △ H (dotriacontan) 3) {△ H (hexane) x △ H (dotriacontan) タ ン /｝
H (benzene) × △ H (dimethylsulfoxide)｝ 4) △ H (hexane) × {△ H (tertiary butanol) + △ H (dotriacontan)} + △ H (benzene) × {△ H (normal butanol) ) + △ H (dimethylsulfoxide) 5) △ H (normal butanol) × △ H (dotriacontane) 6) △ H (tertiary butanol) × △ H (dotriacontane) 7) {△ H (dimethylsulfoxide) ) + △ H (normal butanol)} × {△ H (tertiary butanol) + △ H (dotriacontane)} 8) {△ H (tertiary butanol) × △ H (dotriacontane)}
/ {△ H (normal butanol) × △ H (dimethylsulfoxide)} 9) △ H (dotriacontane) 10) {△ H (dotriacontane) + △ H (tertiary butanol)} / {△ H (dimethyl) Sulfoxide) + {H (normal butanol)}

The relationship between these values 1) to 10) and the discharge capacity of the battery all show a similar tendency, and 1) to 10).
Any of the values of irrespective of the identity of the test carbon material,
The non-graphitizable carbon material, the easily graphitizable carbon material, and the graphite-based carbon material can be used as an index for evaluating the carbon material for a battery without being treated separately. Among these indices, the values of 2), 6) and 10), which have relatively small data variations, are considered to be preferable indices.

The relationship between the indices 2), 6) and 10) and the discharge capacity is shown in FIGS. From FIG. 1, the discharge capacity 2
For the production of a battery of 00 mAh / g or more, the value of 2) above is 60 m
It is understood that it is necessary to use a carbon material of J ² / m ⁴ or more. From FIG. 2, it can be seen that in order to manufacture a battery having a discharge capacity of 200 mAh / g or more, it is necessary to use a carbon material having the value of 6) of 500 mJ ² / m ⁴ or more. From FIG. 3, the above-mentioned 10) is necessary for the production of a battery having a discharge capacity of 200 mAh / g or more.
It is understood that it is necessary to use a carbon material having a value of 0.22 or more.

Similarly, if the relationship between the other values and the discharge capacity is shown, in order to manufacture a battery having a discharge capacity of 200 mAh / g or more, the carbon material must have the value of 1) of 30 mJ ² / m ^4.
The value of the above 3) is 0.1 or more; the value of the above 4) is 200 mJ ² / m ⁴ or more; and the value of 5) is 1300 mJ ² / m ⁴ or more The value of 7) is 700
0 mJ ² / m ⁴ or more; 8) above is 0.05 or more; or 9) above 30 mJ / m ² or more.

However, it should be noted that among the non-graphitizable carbon materials, there is a material which gives a battery having a small discharge capacity despite the above index value being sufficiently large. Therefore,
Although these indices 1) to 10) can handle all three types of carbon materials, they seem to be more suitable for evaluating graphitizable carbon materials and graphite-based carbon materials.

Embodiment 2 FIG. When the relationship between the contact heat per unit area (mJ / m ² ) and the discharge capacity of the battery was examined in the same manner as in Example 1, the relationship was obtained from the contact heat per unit area (mJ / m ² ). It has been found that the following values 11) to 13) can be used as indicators of the discharge capacity of the battery. 11) ΔH (dimethyl sulfoxide) × ΔH (tertiary butanol) 12) ΔH (normal butanol) × ΔH (tertiary butanol) 13) ΔH (dimethyl sulfoxide) × ΔH (normal butanol)

The relations between the values of 11) to 13) and the discharge capacity of the battery all show a similar tendency, and
Regardless of the value of 3), regardless of the characteristics of the test carbon material, the carbon material for batteries is evaluated without treating all of the non-graphitizable carbon material, easily graphitizable carbon material, and graphite-based carbon material. Can be used as an indicator. Among these indices, the value of 13) in which the variation in data is relatively small seems to be a preferable index.

FIG. 4 shows the relationship between the value of the above 13) and the discharge capacity of the battery. FIG. 4 indicates that the value of 13) is 1.3 × 10 ⁴ mJ ² / for the production of a battery having a discharge capacity of 200 mAh / g or more.
It can be seen that a carbon material of m ⁴ or less should be selected.

Similarly, if the relationship between the values of 11) and 12) and the discharge capacity is shown, in order to manufacture a battery having a discharge capacity of 200 mAh / g or more, the carbon material must have the value of 1) of 1). × 10 ⁴ mJ ² / m ⁴ or less, or 1
The value of 2) needs to be 5 × 10 ³ mJ ² / m ⁴ or less.

Index values 1) to 10) obtained in Example 1
When the index values 11) to 13) obtained in this example are compared with each other, as can be seen by comparing FIGS. 1 to 3 with each other, their data distribution patterns are different, and the index values 1) to 13) are different. 1
It can be seen that the test carbon material was evaluated from a viewpoint different from 0) and the index values 11) to 13). Indicator 1)
In 10) to 10), except for some non-graphitizable carbon materials, the larger the index value of the test carbon material, the larger the discharge capacity of the produced battery tends to be.
In 13) to 13), the test carbon material can be divided into two groups: a group having a large battery discharge capacity and a small index value; and a group having a small battery discharge capacity and a large index value. There is no fixed relationship between the discharge capacity and the magnitude of the discharge capacity.

However, the indices 11) to 13) correspond to the non-graphitizable carbon material having a low discharge capacity of the battery despite the high index values observed in the indices 1) to 10).
It can be clearly distinguished from other test carbon materials having a large discharge capacity of batteries. From the above, as an index used for evaluating a carbon material for a battery irrespective of the identity of the carbon material, all of the indexes 1) to 13) according to the present invention can be used alone, but with higher accuracy. It is preferable to use a combination of at least one index selected from indices 1) to 10) and at least one index selected from indices 11) to 13).

Embodiment 3 FIG. The relationship between the contact heat per unit area (mJ / m ² ) and the discharge capacity of the battery was examined in the same manner as in Example 1 except that five types of artificial graphite were further used as the test carbon material. It was found that the value of the following 14) obtained from the contact calorific value per unit area (mJ / m ² ) can be used as an index of the discharge capacity of the battery. 14) ΔH (dotriacontan) / ΔH (dimethyl sulfoxide)

FIG. 5 shows the relationship between the value of the above 14) and the discharge capacity of the battery. From FIG. 5, it can be seen that, for the production of a battery having a discharge capacity of 200 mAh / g or more, a carbon material having the value of 14) of 0.4 or more should be selected.

The relationship between the index 14) and the discharge capacity of the battery shows a tendency similar to the indexes 1) to 10) obtained in the first embodiment.
10), there is no non-graphitizable carbon material having a low discharge capacity of the battery despite the high index value, and the discharge capacity of the battery is determined according to the degree of graphitization of the carbon material. The trend is clearly shown. Also, unlike the indices 11) to 13) obtained in Example 2, the higher the index value, the greater the discharge capacity of the manufactured battery.

From the above, the index 14) is used for the battery without distinguishing all of the non-graphitizable carbon material, the easily graphitizable carbon material and the graphite-based carbon material regardless of the identity of the test carbon material. It can be suitably used as an index for evaluating a carbon material.

Embodiment 4 FIG. Using Lonza artificial graphite KS-6 as a reference, and using graphite fine particles (MSG) vapor-phase grown at a relatively low temperature as artificial graphite to supplement the data of KS-6, various chemicals of carbon materials were used. Properties were evaluated relatively. As the test carbon material, a non-graphitizable carbon material, a graphitizable carbon material, and a graphite-based carbon material were used.

The non-graphitizable carbon is classified into three groups according to the starting material (base agent / crosslinking agent), and further classified into two groups according to the processing temperature in producing the carbon material. A1, A2, B1, B
2, 6 kinds of C1 and C2 were tested. As the graphitizable carbon, six types of M1 to M6, which are mesophase carbon microbeads classified according to heat treatment conditions (oxygen concentration and treatment time) when producing a carbon material, were used. Graphite-based carbon materials are N1 to N4 (average particle size: N1 <N2 <N3 <
N4) were tested. All of these test carbon materials are the same as the carbon materials used in the development of the carbon material evaluation method previously proposed by the present inventors (see Japanese Patent Application No. 7-231710).

In the same manner as in Example 1, the contact heat of all the artificial graphite and the test carbon material with the above seven organic solvents was measured, and the discharge capacity of the battery was measured. At that time, the contact calorific value (mJ / m ² ) converted to the value per unit area according to the usual method
As for KS-6 and MSG, the seven kinds of organic solvents used can be classified into the following two series of hexane series and benzene series, and the following equations are established in each series. There was found.

[0057]

[Table 1] Hexane series (contact calorie ratio: KS-6 / MSG =
3.25) Contact heat of hexane x 2.3 = Contact heat of tertiary butanol Contact heat of hexane x 3.1 = Contact heat of dotriacontane Benzene series (contact calorific ratio: KS-6 / MSG =
2.30) Contact heat of benzene x 2.0 = contact heat of normal butanol Contact heat of benzene x 5.4 = contact heat of dimethyl sulfoxide Contact heat of benzene x 1.0 ≒ contact heat of pyridine

In the above, all units of the contact calorific value are mJ /
m ^2, and the contact heat ratio of KS-6 and MSG is the mean value of ratios obtained in all solvents in each series, and coefficients in each equation, obtained for KS-6 and MSG This is the average of the values. Further, since the contact heat of benzene and the contact heat of pyridine are almost equal (the coefficient is almost 1), the benzene series can be treated as a pyridine series.

Using these two series, an index based on KS-6 was obtained. That is, for KS-6, it is the contact calorie (mJ / m ² ) with each organic solvent △ (organic solvent) and the contact calorie with hexane or benzene, which is the reference solvent of the series to which the organic solvent belongs, △ H When the ratio of △ H (organic solvent) / △ H (hexane) or the ratio of △ H (organic solvent) / △ H (benzene) is calculated from (hexane) or △ H (benzene), this value is calculated by the coefficient of the above equation. Is divided by the coefficient of the corresponding equation,
The value obtained for KS-6 is 1 for all organic solvents. By performing the same calculation for each sample, the value obtained when the behavior of each sample is more similar to KS-6 in each series is closer to 1, and the value farther from 1 is obtained when the behavior is different from KS-6. Therefore, these calculated values can be used as indices for evaluating the characteristics of each sample on the basis of KS-6. Naturally, it is possible to compare and evaluate the absolute value of the calculated value obtained from each sample without dividing by the coefficient of the above equation. Is often easy to grasp.

Although these indices can be used to evaluate the properties of each sample relatively even when used alone, a combination of a plurality of indices can be used for more diversified evaluations. For example, the value for tertiary butanol is referred to as the relative ratio of tertiary butanol). However, since the value relating to the solvent in which the coefficient of the equation representing the relationship within the series is 1 cannot be used as an index because it is always 1, the index obtained in this example is tertiary butanol of the hexane series. And dotriacontane, and benzene series normal butanol and dimethyl sulfoxide, respectively.

Therefore, the test carbon material was evaluated by combining the obtained four types of indices. Specifically, evaluation was performed by drawing a quadrupole diagram from the obtained index values. At this time, the relative ratio of tertiary butanol was plotted in the right (+) direction on the horizontal axis, and the relative ratio in the left (-) direction on the horizontal axis. Quadrupole diagrams were prepared in which the relative ratio of triacontane, the relative ratio of dimethyl sulfoxide in the (+) direction above the vertical axis, and the normal ratio of normal butanol in the (-) direction below the vertical axis were respectively taken. In this quadrupole diagram, KS
-6 is represented as a figure drawn by connecting one point on each axis, and the relative chemical properties of each sample are represented by the shape (balance of each relative ratio) and the size (balance of each relative ratio) with this figure. Size).

Table 1 below shows the relative ratio (reference: mJ / m ² ) and discharge capacity of each organic solvent obtained for the non-graphitizable carbon material, and FIG. 6 shows a quadrupole diagram. In FIG. 6, KS-
6 is drawn as a perfect circle passing through one point on each axis. still,
The meanings of the abbreviations used in the tables in this specification are as follows. H: Hexane B: Benzene tBt: Tertiary butanol nBt: Normal butanol Py: Pyridine DMSO: Dimethyl sulfoxide Dc: 2% dotriacontane / hexane solution

[0063]

[Table 2]

As can be seen from Table 1 above, samples A1, A
2 and C1 have a practical level discharge capacity (200 mAh /
Samples B1, B2 and C2 showed discharge capacities substantially lower than practical levels, although they showed a discharge capacity close to g). For this reason, in Samples B1 and B2, the mixing ratio of the main agent / crosslinking agent is not appropriate, and in Samples C1 and C2, the mixing ratio of the main agent / crosslinking agent is hardly appropriate, but depending on the processing temperature during the production of the carbon material, the mixing ratio is considerable. It can be seen that the disadvantage of the above can be compensated.

FIG. 6 shows that this difference in discharge capacity depending on the sample can be read from the quadrupole diagram. The non-graphitizable carbon material to be tested was generally expressed as a narrow rhombus elongated in the vertical axis direction. Among them, C2 having the smallest discharge capacity has the smallest width. B with small discharge capacity
Although 1 and B2 have a large horizontal width, they have a small spread in the left (-) direction on the horizontal axis and a large spread in the right (+) direction on the horizontal axis. Since this tendency is also observed in C2 while the width is narrow, in the quadrupole diagram of this embodiment, the relative ratio of the carbon material which draws a figure deviated rightward (+) on the horizontal axis, that is, the tertiary butanol is relative to the dotria. Carbon materials larger than the relative ratio of Kontan appeared to tend to show smaller discharge capacities.

Next, Table 2 below shows the plane spacing and half width of the test non-graphitizable carbon material obtained by the conventional physical evaluation method, and the evaluation results of the material obtained by the evaluation method of the present invention. And the discharge capacity of the material.

[0067]

[Table 3]

As is evident from Table 2 above, A1 and A2 and C1 and C2 cannot be distinguished from each other by the plane spacing conventionally used as an index of the carbon material. In both cases, the difference between the evaluation results according to the present invention and the discharge capacity of each sample cannot be explained.

Table 3 below shows the relative ratio (standard: mJ / m ² ) of each organic solvent obtained for the test graphitizable carbon material and the discharge capacity of the battery, and FIG. 7 shows a quadrupole diagram. In FIG. 7, KS-6 is drawn as a perfect circle passing through one point on each axis.

[0070]

[Table 4]

As can be seen from Table 3, the test graphitizable carbon materials except for M3 exhibited discharge capacities higher than the practical level. M3 is also close to the practical level, but the difference from other graphitizable carbon materials is about 40 mAh / g. M1 to M3 have a lower discharge capacity than M4 to M6,
This indicates that the heat treatment conditions (oxygen concentration and treatment time) for producing the carbon material in M4 to M6 are more preferable than those in M1 to M3.

FIG. 7 shows the difference between the discharge capacities. That is, the graphitizable carbon material is generally depicted as a rhombus elongated in the horizontal axis (-) direction, but M2 and M3 are represented as vertically elongated diamonds, and only M3 is the horizontal axis (+). I draw figures that are biased in the direction. The figure deviated in the horizontal axis (+) direction is a figure pattern having a small discharge capacity obtained for the non-graphitizable carbon material. Therefore, according to the evaluation method of the present invention, only the discharge capacity of M3 is different from that of the other samples. , Which was in agreement with the value actually obtained. The elongated rhombic figures obtained for M2 and M3, although fairly small in size, resemble the overall pattern of the non-graphitizable carbon material and the balance of the relative ratio of each organic solvent is similar to that of the non-graphitizable carbon material. It turns out that they are similar. If only the graphic pattern affects the discharge capacity, M2 and M3 should show the same discharge capacity as the non-graphitizable carbon material, but actually show a larger discharge capacity. From this, it was considered that at least in the vertically long rhombic figure pattern, the discharge capacity tends to be small even if the value of each relative ratio is too large.

Next, Table 4 below shows the plane spacing and half width of the test graphitizable carbon material obtained by the conventional physical evaluation method, and the evaluation results of the material obtained by the evaluation method of the present invention. And the discharge capacity of the material.

[0074]

[Table 5]

As is clear from Table 4 above, M1 to M6 cannot be distinguished at all from the plane spacing conventionally used as an index of the carbon material, and both the plane spacing and the half width are evaluation results according to the present invention. Also, the difference in the discharge capacity of each sample cannot be explained.

Table 5 below shows the relative ratio (reference: mJ / m ² ) of each organic solvent obtained for the two types of graphite-based carbon materials and the discharge capacity of the battery, and FIG. 8 shows a quadrupole diagram. In FIG. 8, KS-6 is drawn as a perfect circle passing through one point on each axis.

[0077]

[Table 6]

As can be seen from Table 5, the two types of graphite-based carbon materials both exhibited discharge capacities sufficiently exceeding the practical level, but N2 exhibited a larger discharge capacity than N3. It can be seen from FIG. 8 that the graphite-based carbon material is drawn as a diamond that is strongly stretched in the left (-) direction on the horizontal axis as a whole. This oblong diamond-shaped figure resembles the overall figure pattern of the graphitizable carbon material, but is more strongly stretched to the left (-) on the horizontal axis,
In addition, the figure is deviated in the (-) direction below the vertical axis. And, N2 having a larger discharge capacity draws a figure which is further deviated to the left (-) direction of the horizontal axis than N3, and in consideration of the result obtained with the graphitizable carbon material, in this embodiment, In the quadrupole diagram, it seems that the discharge capacity tends to increase as the relative ratio of dotriacontane is larger than the relative ratio of tertiary butanol.

To summarize the findings obtained for the above three types of carbon materials, in the quadrupole diagram according to the present invention, 1) the three types of carbon materials can be distinguished because they each draw a unique graphic pattern, that is, The non-graphitizable carbon material draws a large vertical diamond, and the graphitizable carbon material draws a relatively small rhombus whose vertical ratio or dotriacontane's relative ratio is larger than that of tertiary butanol. Draws a rather long rhombus with a relative ratio of dotriacontan greater than the relative ratio of tertiary butanol and a relative ratio of normal butanol greater than the relative ratio of dimethyl sulfoxide; 2) relative ratio of dotriacontan Is smaller than the relative ratio of tertiary butanol, the discharge capacity of the battery tends to be small. In the figure pattern of the shape, when the value of each relative ratio is too large, the discharge capacity of the battery tends to decrease. 4) The discharge capacity of the battery increases as the relative ratio of dotriacontan is larger than that of tertiary butanol. Tends to be large.

The characteristics of such a carbon material are obtained by combining a plurality of indices and setting them as relative values to a reference value.
By further charting, it is represented in a very clear form and can be easily grasped.

Embodiment 5 FIG. A battery was manufactured using the carbon material selected by the evaluation method of the present invention for the negative electrode. First, the contact heat between the carbon material and four kinds of organic solvents, hexane, dotriacontane, dimethyl sulfoxide, and normal butanol, was measured, and the obtained contact heat (mJ) was measured.
/ g) in accordance with the usual method, contact heat per unit area (mJ / m ² )
After that, the values of ΔH (hexane) × ΔH (dotriacontane) and ΔH (dimethylsulfoxide) × ΔH (normal butanol) were determined.

First, the discharge capacity of the battery shown in FIG.
For the purpose of obtaining a discharge capacity of 200 mAh / g or more, a carbon material having the above value of 60 mJ ² / m ⁴ or more was selected based on the relationship of the value of H (hexane) × ΔH (dotriacontane). Next, from the selected carbon materials, the discharge capacity of the battery shown in FIG. 4 and ΔH (dimethyl sulfoxide) ×
Based on the relationship of ΔH (normal butanol), the above-mentioned value was set to 6 for the purpose of obtaining a discharge capacity of 200 mAh / g or more.
Carbon materials with 0 mJ ² / m ⁴ or more were further selected.

Next, a battery was manufactured using the carbon material selected in two stages. Using 45 parts by weight of an NMP solution as a coating solvent, 5 parts by weight of PVDF as a binder was dissolved in the solution to form a binder solution, and a carbon material 50
The weight part was added to obtain a coating liquid for a negative electrode. The obtained negative electrode coating liquid was applied on a copper foil current collector having a thickness of 20 μm and dried to prepare a negative electrode sheet having a thickness of about 100 μm. Similarly, to 50 parts by weight of the binder solution,
45 parts by weight of lithium cobaltate and 5 parts by weight of graphite were added to obtain a coating solution for a positive electrode.
It was coated on a 0-micron aluminum foil current collector and dried to produce a positive electrode sheet having a thickness of about 100 microns.

Then, 1 mol / l of lithium perchlorate was dissolved in a 1: 1 mixed solvent of ethylene carbonate and dimethoxyethane to prepare an electrolytic solution. Using these materials and a 2025 type cell (diameter 2 cm, thickness 2.5 mm), a coin-type battery was produced.

Embodiment 6 FIG. A battery was manufactured using the carbon material selected by the evaluation method of the present invention for the negative electrode. First, the contact heat between the carbon material and the two organic solvents, dotriacontan and dimethylsulfoxide, was measured.
After the obtained contact heat (mJ / g) was converted into a contact heat per unit area (mJ / m ² ) according to a conventional method, the ratio ΔH (dotriacontane) / ΔH (dimethylsulfoxide) was determined. FIG.
And the discharge capacity of the battery shown in Fig.
Based on the relationship with the H (dimethylsulfoxide) ratio, a carbon material having the above ratio of 0.4 or more was selected for the purpose of obtaining a discharge capacity of 200 mAh / g or more.

Next, a battery was manufactured using the selected carbon materials. Using 45 parts by weight of an NMP solution as a coating solvent, 5 parts by weight of PVDF as a binder were dissolved to prepare a binder solution, and 50 parts by weight of a carbon material was further added to obtain a coating solution for a negative electrode. The obtained negative electrode coating liquid was applied on a copper foil current collector having a thickness of 20 μm and dried to prepare a negative electrode sheet having a thickness of about 100 μm. Similarly, to 50 parts by weight of the binder solution, 45 parts by weight of lithium cobaltate and 5 parts by weight of graphite were added to prepare a coating solution for a positive electrode.
A positive electrode sheet having a thickness of about 100 μm was prepared by coating and drying on a micron aluminum foil current collector.

Then, 1 mol / l of lithium perchlorate was dissolved in a 1: 1 mixed solvent of ethylene carbonate and dimethoxyethane to prepare an electrolytic solution. Using these materials and a 2025 type cell (diameter 2 cm, thickness 2.5 mm), a coin-type battery was produced.

Embodiment 7 FIG. A battery was manufactured using the carbon material selected by the evaluation method of the present invention for the negative electrode. First, carbon material, hexane, benzene, pyridine,
The heat of contact with seven kinds of organic solvents of normal butanol, tertiary butanol, dimethyl sulfoxide and dotriacontane was measured, and the obtained heat of contact (mJ / g) was calculated according to a conventional method. After conversion to mJ / m ² ), according to the method described in Example 4, relative ratios of four organic solvents of normal butanol, tertiary butanol, dimethyl sulfoxide and dotriacontane based on KS-6 And a quadrupole diagram was prepared. Then, based on the obtained quadrupole diagram, a carbon sample was selected which was 1) drawn in a horizontally long diamond shape and 2) the relative ratio of dotriacontane was sufficiently larger than the relative ratio of tertiary butanol.

Next, a battery was manufactured using the selected carbon material. Using 45 parts by weight of an NMP solution as a coating solvent, 5 parts by weight of PVDF as a binder were dissolved to prepare a binder solution, and 50 parts by weight of a carbon material was further added to obtain a coating solution for a negative electrode. The obtained negative electrode coating liquid was applied on a copper foil current collector having a thickness of 20 μm and dried to prepare a negative electrode sheet having a thickness of about 100 μm. Similarly, to 50 parts by weight of the binder solution, 45 parts by weight of lithium cobaltate and 5 parts by weight of graphite were added to prepare a coating solution for a positive electrode.
A positive electrode sheet having a thickness of about 100 μm was prepared by coating and drying on a micron aluminum foil current collector.

Then, 1 mol / l of lithium perchlorate was dissolved in a 1: 1 mixed solvent of ethylene carbonate and dimethoxyethane to prepare an electrolytic solution. Using these materials and a 2025 type cell (diameter 2 cm, thickness 2.5 mm), a coin-type battery was produced.

[0091]

According to the method for evaluating a carbon material according to the present invention, it is possible to clarify the chemical characteristics of the negative electrode-like carbon material of a lithium ion battery and to evaluate the battery characteristics without actually manufacturing a battery. Can be. Moreover, the method of the present invention can be performed in a short time and at low cost,
Reduce the cost of battery production. According to the present invention,
Based on a chemical evaluation method, a high-performance carbon material for a lithium-ion battery and a high-performance lithium-ion battery using the same can be provided at low cost and with high reliability.

[Brief description of the drawings]

[Fig. 1] Contact heat between carbon material and organic solvent (mJ / m
² ) product, ΔH (hexane) × ΔH (dotriacontan)
And the discharge capacity (mAh / g) of the battery manufactured using the material
FIG.

Fig. 2 Contact heat between carbon material and organic solvent (mJ / m
² ), ΔH (tertiary butanol) × ΔH (dotriacontane), and the discharge capacity (mAh /
It is a figure which shows the relationship with g).

Fig. 3 Contact heat between carbon material and organic solvent (mJ / m
² ) The ratio of the total value, {H (dotriacontane) + {H (tertiary butanol)} / {{H (dimethylsulfoxide) + {H (normal butanol)}}, and a battery manufactured using the material FIG. 5 is a diagram showing a relationship between the discharge capacity (mAh / g) and the discharge capacity.

Fig. 4 Contact heat between carbon material and organic solvent (mJ / m
FIG. 2 is a diagram showing the relationship between the product of ² ), ΔH (dimethyl sulfoxide) × ΔH (normal butanol), and the discharge capacity (mAh / g) of a battery manufactured using the material.

Fig. 5 Contact heat between carbon material and organic solvent (mJ / m
FIG. ² is a diagram showing the relationship between the ratio of ² ), ΔH (dotriacontane) / ΔH (dimethylsulfoxide), and the discharge capacity (mAh / g; mAh / m ² ) of a battery manufactured using the material. .

FIG. 6 is a graph showing the relationship between the contact calorific value (mJ / m ² ) obtained from six types of non-graphitizable carbon materials and the relative value based on artificial graphite KS-6. FIG. 4 is a quadrupole diagram showing chemical characteristics.

FIG. 7 is a graph of graphitizable carbon material obtained by converting contact heat (mJ / m ² ) obtained from six types of graphitizable carbon material into relative values based on artificial graphite KS-6. FIG. 4 is a quadrupole diagram showing chemical characteristics.

FIG. 8 is a graph showing the chemical properties of a graphite-based carbon material obtained by converting contact heat (mJ / m ² ) obtained from four types of graphite-based carbon materials into relative values based on artificial graphite KS-6. FIG. 4 is a quadrupole diagram showing features.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01M 4/02-4/04 H01M 4/58 H01M 4/96 H01M 10/40 G01N 25/20

Claims (13)

(57) [Claims] 1. A non- graphitizable carbon material and a graphitizable carbon.
At least one selected from carbon materials and graphite-based carbon materials
The above carbon material, hexane, 2% dotriacontan
/ Hexane solution, benzene or pyridine, normalbu
Tanol, tertiary butanol and dimethyl sulfoxide
Per unit area calculated by measuring the heat of contact (mJ / g)
Heat of contact (mJ / m ² ) and / or multiple contacts
The calculated value obtained from the calorific value (mJ / m ² ) and the carbon material
The carbon material obtained by evaluating a battery produced using
The correlation between the discharge capacity of the sample and the carbon material is the same as or different from that of the carbon material.
/ g), and evaluating the discharge capacity of the subject carbon material based on the correlation investigated in advance.
A method for evaluating cell carbon material, coordinate four directions its orthogonal coordinates the calculated value four selected and
Create quadrupole plots for each, and
Is used for the evaluation of the subject carbon material.
Said evaluation method. 2. A value obtained from artificial graphite having an ideal graphite structure and corresponding to the calculated value as a reference value,
The evaluation method according to claim 1 , wherein the calculated value is a relative value with respect to the reference value. 3. A carbon material which is a graphitizable carbon material and / or a graphite-based carbon material, and hexane (H), a 2% dotriacontan / hexane solution (Dc /
H), benzene (B), normal butanol (nBt),
Contact heat per unit area (mJ / m) calculated by measuring the contact heat (mJ / g) with one or more kinds of organic solvents selected from the group consisting of tertiary butanol (tBt) and dimethyl sulfoxide (DMSO) ² : The following calculated value obtained from △ H (organic solvent name)): 1) △ H (H) × △ H (tBt), 2) △ H (H) × △ H (Dc / H) , 3) {△ H (H) × △ H (Dc / H)｝ / ｛△ H (B) × △ H (D
MSO)｝, 4) × H (H) × {ｔH (tBt) + △ H (Dc / H)} + △ H
(B) × {△ H (nBt) + △ H (DMSO)}, 5) △ H (nBt) × △ H (Dc / H), 6) △ H (tBt) × △ H (Dc / H), 7) {△ H (DMSO) + △ H (nBt)} × {△ H (tBt)
+ △ H (Dc / H)}, 8) {△ H (tBt) × △ H (Dc / H)} / {△ H (nBt) ×
ΔH (DMSO)}, 9) ΔH (Dc / H), or 10) {ΔH (Dc / H) + ΔH (tBt)} / {ΔH (DMS
O) + {H (nBt)}, and the correlation between the discharge capacity of a battery manufactured using the carbon material and the same or different type of the carbon material. The contact heat between the test carbon material and the organic solvent is measured, the calculated value is obtained, and the discharge capacity of the battery manufactured using the test carbon material is evaluated based on the correlation investigated in advance. A method for evaluating a carbon material for a battery, comprising: 4. A carbon material comprising a non-graphitizable carbon material, at least one selected from a graphitizable carbon material and a graphite-based carbon material, hexane (H), 2%
Contact with one or more organic solvents selected from the group consisting of dotriacontan / hexane solution (Dc / H), benzene (B), normal butanol (nBt), tertiary butanol (tBt), and dimethyl sulfoxide (DMSO) The following calculated value obtained from the contact calorie per unit area (mJ / m ² : hereinafter represented by ΔH (organic solvent name)) calculated by measuring the calorific value (mJ / g): 1) ΔH (H ) × △ H (tBt), 2) △ H (H) × △ H (Dc / H), 3) {△ H (H) × △ H (Dc / H)｝ / ｛△ H (B) × △ H (D
MSO)｝, 4) △ H (H) × {) H (tBt) + △ H (Dc / H)} + △ H
(B) × {△ H (nBt) + △ H (DMSO)}, 5) △ H (nBt) × △ H (Dc / H), 6) △ H (tBt) × △ H (Dc / H), 7) {△ H (DMSO) + △ H (nBt)} × {△ H (tBt)
+ △ H (Dc / H)}, 8) {△ H (tBt) × △ H (Dc / H)} / {△ H (nBt) ×
ΔH (DMSO)}, 9) ΔH (Dc / H), or 10) {ΔH (Dc / H) + ΔH (tBt)} / {ΔH (DMS
O) + {H (nBt)} and a discharge capacity of a battery manufactured using the carbon material; and a correlation between the two or more carbon materials, normal butanol, The following calculated value obtained from the contact heat per unit area (mJ / m ² ) calculated by measuring the contact heat with two kinds of organic solvents selected from the group consisting of tert-butanol and dimethylsulfoxide: 11) ΔH (DMSO) × △ H (tBt), 12) △ H (nBt) × △ H (tBt), or 13) △ H (DMSO) × △ H (nBt), and the carbon material The correlation between the discharge capacity of the battery prepared using the method is investigated in advance, and the calculated value is obtained by measuring the contact heat between the carbon material to be tested or the same or different carbon material to be tested and the organic solvent. , Preset Based on the correlation, and evaluating the discharge capacity of the battery manufactured using the analyte-carbon material, method for evaluating cell carbon material. 5. A contact heat per unit area calculated by measuring a contact heat (mJ / g) between a carbon material and a 2% dotriacontane / hexane solution (Dc / H) and dimethyl sulfoxide (DMSO). (MJ / m ² : hereinafter represented by ΔH (organic solvent name).) 14) ΔH (Dc) /
The correlation between ΔH (DMSO) and the discharge capacity of a battery manufactured using the carbon material is investigated in advance, and the contact between the organic solvent and the carbon material to be inspected, which is the same or different from the carbon material, is performed. Measuring the heat, obtaining the calculated value, and evaluating the discharge capacity of the battery produced using the subject carbon material based on the correlation previously investigated; Evaluation methods. 6. A carbon material, hexane (H), 2%
Dotriacontan / hexane solution (Dc / H), benzene (B) or pyridine (Py), normal butanol (n
Bt), tertiary butanol (tBt) and dimethylsulfoxide (DMSO). The contact calorie per unit area (mJ / m ² : below) calculated by measuring the contact calorie (mJ / g)
H (organic solvent name). )), The following four calculated values: a) △ H (tBt) / △ H (H), b) △ H (Dc / H) / △ H (H), c) △ H (DMSO) / △ (B) or {H (DMSO) /}
(Py), and d) △ H (nBt) / △ (B) or △ H (nBt) / △ (P
y), and a) in the right (+) direction of the horizontal axis, b) in the left (-) direction of the horizontal axis, c) in the (+) direction above the vertical axis, and The correlation between the quadrupole diagram obtained by plotting the value of d) in the −) direction and the discharge capacity of a battery manufactured using the carbon material is investigated in advance, and the same or different type of the carbon material is used. The contact heat between the test carbon material and the organic solvent is measured to obtain the calculated value and the quadrupole diagram, and based on the correlation investigated in advance, a battery manufactured using the test carbon material is used. A method for evaluating a carbon material for a battery, comprising evaluating a discharge capacity. 7. An artificial graphite having a graphite structure close to ideal, hexane, 2% dotriacontane / hexane solution,
Benzene, normal butanol, tertiary butanol and dimethyl sulfoxide are obtained from the contact heat per unit area (mJ / m ² ) calculated by measuring the contact heat (mJ / g), and the calculated value a), Using the calculated values a ′), b ′), c ′) and d ′) corresponding to b), c) and d) as reference values, the calculated values a), b) and c obtained from the carbon material, respectively. 7. The evaluation method according to claim 6 , wherein d) and d) are converted into a relative value with respect to the reference value. Wherein said artificial graphite, characterized in that it is a KS-6 type artificial graphite, evaluation method according to claim 2 or 7. 9. A method of evaluating a carbon material by the evaluation method according to claim 3 to select a carbon material exhibiting a desired discharge capacity, and using the selected carbon material for a negative electrode. A method for producing a lithium ion battery, which is characterized in that: 10. A carbon material showing a desired discharge capacity by evaluating a carbon material by the evaluation method according to any one of claims 1 to 2 and 6 to 8 , and using the selected carbon material as a negative electrode. A method for producing a lithium ion battery, which is used. 11. The evaluation method according to claim 3 , wherein at least one of the calculated values 1) to 10) is calculated, and the calculated value is 30 mJ ² / m ⁴ or more, 2) the value is 60 mJ ² / m ⁴ or more, 3) the value is 0.1 or more, 4) the value is 200 mJ ² / m ⁴ or more, 5) the value is 1300 mJ ² / m ⁴ or more, 6 value of) the 50 mJ ² / m ⁴ or more, the value of 7) 7000mJ ² / m ⁴ or more, the value of 8) is 0.05 or more, the value of 9) is the value of 30 mJ / m ² or more, or 10) A method for producing a lithium ion battery, comprising: selecting a test carbon material satisfying 0.22 or more; and using the selected carbon material for a negative electrode. 12. The evaluation method according to claim 4 , wherein at least one of the calculated values 1) to 10) is calculated, and the obtained calculated value is 30 mJ ² / m ⁴ or more, 2) the value is 60 mJ ² / m ⁴ or more, 3) the value is 0.1 or more, 4) the value is 200 mJ ² / m ⁴ or more, 5) the value is 1300 mJ ² / m ⁴ or more, 6 value of) the 50 mJ ² / m ⁴ or more, the value of 7) 7000mJ ² / m ⁴ or more, the value of 8) is 0.05 or more, the value of 9) is the value of 30 mJ / m ² or more, or 10) 0.22 or more is satisfied, and at least one of the calculated values 11) to 13) is calculated, and the obtained calculated value is 1 × 10 ⁴ mJ ² / m under the following condition: 11). ⁴ or less, the value of 12) is 5 × 10 ³ mJ ² / m ⁴ or less, or the value of 13) is 1.3 × 10 ⁴ mJ ² / m ⁴ or less. Carbon material for negative electrode Characterized by use, method for producing a lithium-ion type battery. 13. The calculated value 14) is calculated by the evaluation method according to claim 5 , a carbon material to be inspected having a calculated value of 0.4 or more is selected, and the selected carbon material is used for a negative electrode. A method for producing a lithium ion battery.