JP6102231B2 - Negative electrode material for lithium ion secondary battery, negative electrode for lithium ion secondary battery, lithium ion secondary battery, and method for producing negative electrode material for lithium ion secondary battery - Google Patents

Description

  The present invention relates to a negative electrode material for a lithium ion secondary battery, a negative electrode for a lithium ion secondary battery and a lithium ion secondary battery using the negative electrode material, and a method for producing a negative electrode material for a lithium ion secondary battery.

  Lithium ion secondary batteries are lighter and have higher input / output characteristics than other secondary batteries such as nickel cadmium batteries, nickel metal hydride batteries, and lead acid batteries. Therefore, in recent years, it is expected as a power source for high input / output such as a power source used for an electric vehicle, a hybrid electric vehicle and the like. As a power source for a hybrid electric vehicle, a lithium ion secondary battery having an excellent balance of input / output characteristics and excellent life characteristics such as cycle characteristics and storage characteristics is required.

  In general, negative electrode active materials used for lithium ion secondary batteries are roughly classified into graphite and amorphous materials. Graphite has a structure in which hexagonal network surfaces of carbon atoms are regularly stacked, and insertion / extraction reaction of lithium ions proceeds from the end portions of the stacked network surfaces to perform charge / discharge. However, since the insertion / elimination reaction proceeds only at the end, the input / output performance may be low. In addition, since the crystallinity is high and the surface defects are small, there is a problem that the affinity with the electrolytic solution is low and the life characteristics of the lithium ion secondary battery may be deteriorated.

  On the other hand, amorphous carbon typified by hard carbon has irregular hexagonal network surfaces or no network structure, and therefore, lithium insertion / extraction reaction proceeds on the entire surface of the particles. Therefore, it is easy to obtain a lithium ion secondary battery excellent in input / output characteristics. In general, amorphous carbon is roughly classified into two types, hard carbon and soft carbon. Hard carbon is carbon in which crystals do not easily develop even when heat-treated to a high temperature of 2500 ° C. or higher, and soft carbon is carbon that is easily changed to a highly crystalline graphite structure by high-temperature treatment.

  Or, in contrast to graphite, decarbon has low crystallinity on the particle surface and excellent affinity with the electrolyte. Therefore, lithium ion secondary batteries using this as a negative electrode material are compared with those using graphite. And it has the feature that it excels in life characteristics. On the other hand, since the structure is irregular, the irreversible capacity is large and the specific gravity is small, so that it is difficult to increase the electrode density and the energy density is low.

  Therefore, a lithium ion secondary battery having a small irreversible capacity, a large energy density, and excellent input / output characteristics and life characteristics and a negative electrode material for obtaining the lithium ion secondary battery are required. In relation to this, a technique using amorphous carbon as a negative electrode material is disclosed (for example, see Patent Documents 1 and 2).

Japanese Patent Laid-Open No. 04-370662 Japanese Patent Laid-Open No. 05-307956

  The present invention provides a lithium ion secondary battery having a small initial irreversible capacity, a high initial charge / discharge efficiency, a large energy density, and excellent life characteristics compared to a conventional lithium ion secondary battery. To provide a negative electrode material for a secondary battery and a production method thereof, a negative electrode for a lithium ion secondary battery including the negative electrode material for a lithium ion secondary battery, and a lithium ion secondary battery including the negative electrode for the lithium ion secondary battery. With the goal.

Specific means for solving the above problems are as follows.
<1> Carbonaceous particles having a 002 plane distance d002 of 0.340 nm or more and 0.370 nm or less determined by X-ray diffractometer (XRD) measurement, and a particle diameter exceeding 0.5 μm, and the carbonaceous particles Adhering carbonaceous particles having a particle size of 0.5 μm or less attached to the surface of the carbonaceous particles, and the number of adhering carbonaceous particles is more than 0 per surface area of 130 μm ^{2 of the} carbonaceous particles and 50 or less. der is, the type and the type of the attached carbonaceous particles of the carbonaceous particles is a negative electrode material for lithium ion secondary batteries to be the same as.

<2> Carbonaceous particles having a 002 plane spacing d002 of 0.340 nm or more and 0.370 nm or less determined by X-ray diffractometer (XRD) measurement, and a particle diameter exceeding 0.5 μm, and the carbonaceous particles Attached carbonaceous particles having a particle diameter of 0.5 μm or less, and the number of attached carbonaceous particles is 0.0 / μm ² per unit surface area of the carbonaceous particles. der 0.4 pieces / [mu] m ² or less than is, the type and the type of the attached carbonaceous particles of the carbonaceous particles is a negative electrode material for lithium ion secondary batteries to be the same as.

<3> The negative electrode material for a lithium ion secondary battery according to <1> or <2>, wherein a crystallite size (Lc) in the c-axis direction of the carbonaceous particles is 3.3 nm or more and 5.5 nm or less. .

<4> Any one of the above <1> to <3>, wherein the pH at 25 ° C. is 5.6 or more and 6.1 or less when dispersed in pure water so as to have a concentration of 3.8% by mass. It is a negative electrode material for lithium ion secondary batteries as described in above.

<5> Any one of the above items <1> to <4>, wherein a DTA peak is present at 650 ° C. or more and 680 ° C. or less in a differential thermal analysis (DTA) measurement in an air atmosphere at a heating rate of 5 ° C./min It is a negative electrode material for lithium ion secondary batteries as described in any one.

<6> Any of <1> to <5>, wherein the volume average particle diameter (50% D) is 5 μm or more and 30 μm or less, and the true specific gravity is 1.8 g / cm ³ or more and 2.2 g / cm ³ or less. 2. A negative electrode material for a lithium ion secondary battery according to claim 1.

<7> A current collector and a negative electrode material layer that is disposed on the current collector and includes the negative electrode material for a lithium ion secondary battery according to any one of <1> to <6>. It is a negative electrode for lithium ion secondary batteries.

<8> A lithium ion secondary battery comprising the negative electrode for a lithium ion secondary battery according to <7>, a positive electrode, and an electrolyte.

<9> A step of obtaining a pulverized product by pulverizing carbonaceous particles having a 002 plane distance d002 of 0.340 nm or more and 0.370 nm or less determined by X-ray diffractometer (XRD) measurement, and the pulverized product. Is a method for producing a negative electrode material for a lithium ion secondary battery according to any one of the above items <1> to < 6 >, comprising a step of heat-treating at 400 ° C. to 700 ° C. in an air atmosphere. .

  According to the present invention, compared with a conventional lithium ion secondary battery, a lithium ion secondary battery having a small initial irreversible capacity, high initial charge / discharge efficiency, high energy density, and excellent life characteristics can be configured. Provided are a negative electrode material for a lithium ion secondary battery and a manufacturing method thereof, a negative electrode for a lithium ion secondary battery including the negative electrode material for the lithium ion secondary battery, and a lithium ion secondary battery including the negative electrode for the lithium ion secondary battery. can do.

3 is a diagram showing an example of a scanning electron microscope image (magnification 1000 times) of the negative electrode material of Example 1. FIG. 3 is a diagram illustrating an example of a scanning electron microscope image (magnification: 5000 times) of the negative electrode material of Example 1. FIG. 3 is a diagram illustrating an example of a scanning electron microscopic image (magnification of 10,000 times) of the negative electrode material of Example 1. FIG. 3 is a diagram illustrating an example of a scanning electron microscope image (magnification 10,000 times) in a visual field 1 of a negative electrode material of Example 1. FIG. 3 is a diagram showing an example of a scanning electron microscope image (magnification of 10,000 times) in a visual field 2 of a negative electrode material of Example 1. FIG. 3 is a diagram illustrating an example of a scanning electron microscope image (magnification 10,000 times) in a visual field 3 of a negative electrode material of Example 1. FIG. 3 is a diagram illustrating an example of a scanning electron microscope image (magnification: 10,000 times) in a visual field 4 of a negative electrode material of Example 1. FIG. 3 is a diagram illustrating an example of a scanning electron microscope image (magnification 10,000 times) in a visual field 5 of a negative electrode material of Example 1. FIG. 6 is a diagram showing an example of a scanning electron microscope image (magnification 1000 times) of the negative electrode material of Comparative Example 1. FIG. 6 is a diagram showing an example of a scanning electron microscope image (magnification 5000 times) of the negative electrode material of Comparative Example 1. FIG. 6 is a diagram illustrating an example of a scanning electron microscope image (magnification of 10,000 times) of the negative electrode material of Comparative Example 1. FIG. 6 is a diagram illustrating an example of a scanning electron microscope image (a magnification of 10,000 times) in a visual field 1 of a negative electrode material of Comparative Example 1. FIG. 7 is a diagram showing an example of a scanning electron microscope image (magnification of 10,000 times) in a visual field 2 of a negative electrode material of Comparative Example 1. FIG. 6 is a diagram illustrating an example of a scanning electron microscope image (a magnification of 10,000 times) in a visual field 3 of a negative electrode material of Comparative Example 1. FIG. 6 is a diagram illustrating an example of a scanning electron microscope image (10,000 magnifications) in a visual field 4 of a negative electrode material of Comparative Example 1. FIG. 6 is a diagram illustrating an example of a scanning electron microscope image (a magnification of 10,000 times) in a visual field 5 of a negative electrode material of Comparative Example 1. FIG.

  In this specification, the term “process” is not limited to an independent process, and is included in the term if the intended purpose of the process is achieved even when it cannot be clearly distinguished from other processes. . Moreover, the numerical range shown using "to" shows the range which includes the numerical value described before and behind "to" as a minimum value and a maximum value, respectively. Furthermore, the content of each component in the composition means the total amount of the plurality of substances present in the composition unless there is a specific notice when there are a plurality of substances corresponding to each component in the composition.

<Anode material for lithium ion secondary battery and method for producing the same>
The negative electrode material for a lithium ion secondary battery of the present invention is a carbonaceous particle having a 002-plane spacing d002 of 0.340 nm or more and 0.370 nm or less determined by X-ray diffraction measurement (XRD). The average number of adhering carbonaceous particles having a particle diameter of 0.5 μm or less adhered per surface area of 130 μm ^{2 of the} carbonaceous particles observed by (SEM) is 50 or less.
That is, the negative electrode material for a lithium ion secondary battery of the present invention adheres to the first carbonaceous particles having a particle diameter of more than 0.5 μm and the surface of the first carbonaceous particles, and the particle diameter is 0.5 μm. wherein a second carbonaceous particles is m or less, the adhesion speed of the second carbonaceous particles, wherein the first or less 50 per surface area 130 .mu.m ² of carbonaceous particles, X-rays diffractometer A surface distance d002 of the 002 plane obtained by (XRD) measurement is 0.340 nm or more and 0.370 nm or less.

Further, the negative electrode material for a lithium ion secondary battery of the present invention is a carbonaceous particle having a 002-plane spacing d002 of 0.340 nm or more and 0.370 nm or less determined by X-ray diffractometer (XRD) measurement. The negative electrode for a lithium ion secondary battery, wherein the adhered carbonaceous particles having a particle diameter of 0.5 μm or less attached to the surface of the carbonaceous particles are 0.4 particles / μm ² or less per unit surface area of the carbonaceous particles. It is a material.
That is, the negative electrode material for a lithium ion secondary battery of the present invention adheres to the first carbonaceous particles having a particle diameter of more than 0.5 μm and the surface of the first carbonaceous particles, and the particle diameter is 0.5 μm. second carbonaceous particles that are less than or equal to m , and the number of attached second carbonaceous particles is 0.4 or less per μm ² per unit surface area of the first carbonaceous particles, A surface distance d002 of 002 planes determined by X-ray diffractometer (XRD) measurement is 0.340 nm or more and 0.370 nm or less.

  As described above, the negative electrode material for a lithium ion secondary battery of the present invention has a small initial irreversible capacity due to the small number of second carbonaceous particles having a small particle diameter attached to the surface of the first carbonaceous particles. It is possible to construct a lithium ion secondary battery having high initial charge / discharge efficiency, large energy density, and excellent life characteristics.

  Details of the negative electrode material for a lithium ion secondary battery (hereinafter also simply referred to as “negative electrode material”) according to the present invention will be described below. The carbonaceous particles (first carbonaceous particles) serving as the core (raw material) of the negative electrode material of the present invention should have an interplanar spacing d002 of 0.300 nm or more and 0.370 nm or less on the 002 plane of carbon determined by XRD measurement. If it does not specifically limit. From the viewpoint of increasing the irreversible capacity, life characteristics, and charge / discharge capacity of the negative electrode material of a lithium ion secondary battery, in particular, a carbon material exhibiting graphitizability is calcined (calcined) and then pulverized. It is preferable to use the obtained carbonaceous particles such as coke as a raw material. Specifically, a material exhibiting graphitizability is fired (calcined) in an inert atmosphere at 800 ° C. or higher, for example. Next, the obtained fired product is pulverized by a known method such as a jet mill, vibration mill, pin mill, hammer mill, etc., and the particle size is classified and adjusted so that the average particle size is in the range of 5 μm to 30 μm. To obtain carbonaceous particles. Here, the average particle diameter is a volume average particle diameter (50% D).

  Here, the material exhibiting graphitizability is not particularly limited, and examples thereof include thermoplastic resins, naphthalene, anthracene, phenanthrolen, coal tar, tar pitch, etc., preferably coal-based coal. Tar, petroleum-based tar and the like. In addition, when a material exhibiting graphitizability is fired (calcined), heat treatment may be performed at a temperature different from the temperature in the firing treatment in advance before the firing treatment. In this case, the material exhibiting graphitizability is preliminarily heat-treated using, for example, an autoclave or the like, coarsely pulverized, and then calcined in an inert atmosphere at 800 ° C. or higher as described above ( The carbonaceous particles used as the nucleus (raw material) can be obtained by adjusting the particle size by pulverization and classification again. In addition, the temperature of the heat treatment performed before firing (calcination) can be appropriately determined according to the material exhibiting graphitizability to be used, and is not particularly limited. When the material exhibiting graphitizability is coal-based coal tar, petroleum-based tar, or the like, the temperature is preferably 400 ° C to 450 ° C, for example.

  The interplanar spacing d002 of the carbonaceous particles serving as the nucleus (raw material) is not less than 0.340 nm and not more than 0.370 nm, and particularly not less than 0.340 nm and not more than 0.360 nm. When the negative electrode material is used, it is preferable from the viewpoint of improving battery characteristics such as low irreversible capacity, large charge / discharge capacity, and long cycle life. When d002 is less than 0.340 nm, the initial charge / discharge efficiency of the lithium ion secondary battery tends to decrease. On the other hand, if it exceeds 0.370 nm, the life characteristics or input / output characteristics of the lithium ion secondary battery tend to be inferior, which is not preferable. In addition, the surface interval d002 of the 002 plane of the carbon material is determined based on a diffraction profile obtained by irradiating a carbon particle powder sample with X-rays (CuKα rays) and measuring diffraction lines with a goniometer. It can be calculated from the diffraction peak corresponding to the carbon 002 plane appearing in the vicinity of ° using the Bragg equation.

  As a result of analyzing the surface of the carbonaceous particles obtained by firing (calcining) and pulverizing the carbon material exhibiting graphitizability as described above, the present inventors have a particle diameter of 0.5 μm or less on the surface. It was found that a large number of fine carbonaceous particles (attached carbonaceous particles, second carbonaceous particles) were attached. Furthermore, when such carbonaceous particles with a large number of fine carbonaceous particles attached are used as the negative electrode material of a lithium ion secondary battery, the charge / discharge efficiency of the lithium ion secondary battery is low, There were problems such as a large decrease in cycle capacity retention. This is presumed to be due to the fact that the adhering carbonaceous particles described above have a high reaction activity with respect to the electrolyte solution, thereby increasing the irreversible capacity of the first cycle of the negative electrode and reducing the life characteristics of the lithium ion secondary battery. .

  In view of the above, an attempt was made to reduce adhering carbonaceous particles by changing the conditions of the carbonaceous particle classification process. However, it has been found that it is extremely difficult to sufficiently remove the adhered carbonaceous particles by a method using an ordinary classifier or sieve. Therefore, as a result of intensive investigations on another method for reducing the attached carbonaceous particles in the present invention, it was found that the method of removing by oxidation treatment was extremely effective, and the negative electrode of the present invention in which the number of attached carbonaceous particles was reduced. I got the material. Details are described below.

  The oxidation treatment is performed using carbonaceous particles serving as nuclei (raw materials) obtained by firing (calcining) a carbon material exhibiting graphitizability and then pulverizing. At this time, it is desirable to classify and adjust the particle size in advance so that the average particle size of the carbonaceous particles is in the range of 5 μm to 30 μm before the oxidation treatment. The atmosphere in the oxidation treatment of the carbonaceous particles is preferably in the range of 400 ° C. to 700 ° C. in the air, and more preferably in the range of 500 ° C. to 650 ° C. It is preferable at the point from which a material is obtained. When the temperature of the oxidation treatment is 400 ° C. or higher, the effect of the oxidation treatment is sufficiently obtained, and there is a tendency that the reduction of attached carbonaceous particles can be sufficiently achieved. On the other hand, when the temperature is 700 ° C. or lower, it is possible to suppress oxidative combustion of the carbonaceous particles themselves serving as nuclei (raw materials), and the yield of the negative electrode material tends to be improved.

  The oxidation treatment time is preferably 10 minutes to 5 hours, and more preferably 10 minutes to 1 hour in terms of efficiently removing attached carbonaceous particles and increasing the yield of the negative electrode material. When the oxidation treatment time is 10 minutes or longer, the effect of the oxidation treatment is sufficiently obtained, and there is a tendency that the reduction of attached carbonaceous particles can be sufficiently achieved. On the other hand, if it is 5 hours or less, it is possible to suppress oxidative combustion of the carbonaceous particles themselves serving as nuclei (raw materials), and the yield of the negative electrode material tends to be improved.

  Although the processing furnace used for these oxidation treatments is not particularly limited, a muffle furnace, a roller hearth kiln, a rotary kiln, or the like can be used. In addition, as described above, within the condition range of the oxidation treatment aimed at removing attached carbonaceous particles, d002 and Lc of carbonaceous particles serving as nuclei (raw materials) and the carbonaceous material which is the negative electrode material of the present invention. It has been confirmed that there is no change between the particles d002 and Lc.

The attached carbonaceous particles adhering to the surface of the oxidized carbonaceous particles obtained in this way can be examined by the following method. That is, the carbonaceous particles after the oxidation treatment are observed with a scanning electron microscope (SEM). From the SEM image, arbitrary particles having a particle diameter of 20 μm or more are selected, and the state of carbonaceous particles adhering to a relatively flat particle surface is examined at a magnification of about 10,000 times. In the present invention, for example, in the field of view of a 10 μm × 13 μm = 130 μm ² SEM image observed at a magnification of 10,000, the relationship between the number of attached carbonaceous particles having a particle diameter of 0.5 μm or less and the characteristics of the lithium ion secondary battery is shown. Examined. As a result, when the number of attached carbonaceous particles having a particle size of 0.5 μm or less present per 130 μm ² is 50 or less, the initial charge / discharge efficiency of the negative electrode and the cycle life of the lithium ion secondary battery are It turned out to be preferable in terms of improvement. Furthermore, it was found that the number of attached carbonaceous particles having a particle size of 0.5 μm or less is more preferably 30 or less. The fewer adhering carbonaceous particles with a particle size of 0.5 μm or less, the fewer side reactions with the electrolyte solution, the lower the initial irreversible capacity of the negative electrode, the higher the initial efficiency, and the life of the lithium ion secondary battery It was found that the characteristics were improved.
Note that the number of attached carbonaceous particles is measured for five fields of view of the SEM image and is obtained as an arithmetic average value thereof.
The particle diameters of the carbonaceous particles (first carbonaceous particles) and the attached carbonaceous particles (second carbonaceous particles) are determined as the equivalent circle diameter (diameter) of each particle.

In addition, when investigating attached carbonaceous particles adhering to the surface of relatively small particles having a particle diameter of less than 20 μm contained in the oxidized carbonaceous particles, the flat portion of the particles is observed by narrowing down to a narrower area than the above. It is preferable to obtain the number per unit surface area. As a result, when the number of adhering carbonaceous particles having a particle diameter of 0.5 μm or less per unit area 1 μm ^{2 on} the surface of the carbonaceous particles is 0.4 / μm ² or less, the initial efficiency of the negative electrode and lithium It turned out that it is preferable at the point which can improve the cycle life of an ion secondary battery. Furthermore, it was found that the number of attached carbonaceous particles having a particle diameter of 0.5 μm or less is more preferably 0.25 / μm ² or less.

As described above, by oxidizing the carbonaceous particles, it is possible to easily reduce the adhered carbonaceous particles that are extremely difficult to remove by classification and sieving. It is effective in suppressing the reactivity with the liquid, reducing the initial irreversible capacity of the negative electrode, improving the initial efficiency, and improving the life characteristics of the lithium ion secondary battery.
In addition, carbonaceous particles having a particle diameter of more than 0.5 μm may adhere to the carbonaceous particles after oxidation treatment (first carbonaceous particles). The number of attached carbonaceous particles having a particle diameter exceeding 0.5 μm is not particularly limited.

  Further, the negative electrode material of the lithium ion secondary battery preferably has a crystallite size (Lc) in the c-axis direction calculated by Scherrer's equation of 3.3 nm to 5.5 nm, preferably 4.0 nm to 5.2 nm. The following is more preferable. When Lc is 3.3 nm or more, the crystallinity of the carbonaceous particles becomes higher, and the initial charge / discharge efficiency of the lithium ion secondary battery tends to be further improved. On the other hand, when Lc is 5.5 nm or less, the crystallinity of the carbonaceous particles becomes lower, and the charge / discharge capacity tends to increase.

Moreover, when the negative electrode material for lithium ion secondary batteries is disperse | distributed to a pure water, it is preferable to exhibit acidity. Specifically, when dispersed in pure water so as to have a concentration of 3.5% by mass, the pH at 25 ° C. is preferably from 5.6 to 6.1. This is because, for example, a slight amount of oxygen remains on the surface due to the oxidation treatment, so that the functional group containing a C═O bond increases on the surface of the carbon particles, and the pH is 0.2 to 0.7 acid as compared with the case of no treatment. You can think of shifting to the side.
When the negative electrode material for a lithium ion secondary battery contains components other than the first and second carbonaceous particles, the pH is measured by dispersing only the first and second carbonaceous particles.

  Furthermore, the carbonaceous particles that are the negative electrode materials for lithium ion secondary batteries have a DTA peak of 650 ° C. or higher and 680 ° C. or higher in a differential thermal analysis (DTA) measurement at a temperature rising rate of 5 ° C./min in an air atmosphere. It is preferable to exist in the following range. By performing the oxidation treatment, the peak temperature is shifted to a low temperature side of 10 ° C. to 30 ° C. as compared with the case of no treatment. Oxygen atoms are previously introduced into the surface of the carbonaceous particles by the oxidation treatment, so that the oxidation reaction seems to proceed at a lower temperature.

  The negative electrode material for a lithium ion secondary battery has a volume average particle size (50% D) of preferably 5 μm or more and 30 μm or less, and more preferably 5 μm or more and 25 μm or less. When the volume average particle diameter is 5 μm or more, the specific surface area is reduced, the initial charge / discharge efficiency of the lithium ion secondary battery is further improved, and the contact between the particles is improved and the input / output characteristics are further improved. is there. On the other hand, when the volume average particle diameter is 30 μm or less, unevenness is suppressed on the formed electrode surface, the short circuit of the battery is suppressed, and the diffusion distance of Li from the particle surface to the inside is shortened. Therefore, the input / output characteristics of the lithium ion secondary battery tend to be further improved. The volume average particle size is calculated as a particle size corresponding to 50% volume accumulation from the small diameter side in the particle size distribution. The particle size distribution can be measured by dispersing a sample in purified water containing a surfactant and using a laser diffraction particle size distribution measuring apparatus (SALD-3000J, manufactured by Shimadzu Corporation).

Furthermore, the negative electrode material for a lithium ion secondary battery, it is preferable that the true specific gravity of less 1.80 g / cm ³ or more 2.20 g / cm ^3. When the true specific gravity is 1.80 g / cm ³ or more, the charge / discharge capacity per volume of the lithium ion secondary battery is further improved, and the initial charge / discharge efficiency tends to be further increased. On the other hand, when the true specific gravity is 2.20 g / cm ³ or less, the life characteristics of the lithium ion secondary battery tend to be further improved. The true specific gravity can be determined by a pycnometer method using butanol.

<Anode for lithium ion secondary battery>
The negative electrode for lithium ion secondary batteries of this invention contains a collector and the negative electrode material layer containing the said negative electrode material for lithium ion secondary batteries arrange | positioned on the said collector. The negative electrode for lithium ion secondary batteries is prepared by, for example, kneading the negative electrode material for lithium ion secondary batteries and the organic binder of the present invention together with a solvent using a dispersing device such as a stirrer, a ball mill, a super sand mill, or a pressure kneader. A negative electrode material slurry can be prepared and applied to a current collector to form a negative electrode layer. Moreover, it can obtain by shape | molding paste-like negative electrode material slurry in shapes, such as a sheet form and a pellet form, and integrating this with a collector.

  The organic binder is not particularly limited. Examples of the organic binder include styrene-butadiene copolymers; ethylenic polymers such as methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, (meth) acrylonitrile, and hydroxyethyl (meth) acrylate. (Meth) acrylic copolymers formed from saturated carboxylic acid esters and ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, fumaric acid, maleic acid; polyvinylidene fluoride, polyethylene oxide, polyepichrome Examples thereof include polymer compounds such as hydrin, polyphosphazene, polyacrylonitrile, polyimide, and polyamideimide.

The content ratio of the organic binder in the negative electrode layer of the lithium ion secondary battery negative electrode is 0.5 parts by mass to 20 parts by mass with respect to 100 parts by mass in total of the negative electrode material for the lithium ion secondary battery and the organic binder. It is preferable that it is 1 mass part-10 mass parts.
Adhesiveness is good when the content ratio of the organic binder is 0.5 parts by mass or more, and the negative electrode is prevented from being destroyed by expansion and contraction during charge and discharge. On the other hand, it can suppress that electrode resistance becomes large because it is 20 mass parts or less.

  Moreover, you may mix a thickener with a negative electrode material slurry, in order to adjust a viscosity. As the thickener, carboxymethyl cellulose, methyl cellulose, hydroxymethyl cellulose, ethyl cellulose, polyvinyl alcohol, polyacrylic acid (and its salt), oxidized starch, phosphorylated starch, casein and the like can be used.

  The negative electrode material slurry may contain a conductive auxiliary material as necessary. Examples of the conductive auxiliary material include carbon black, graphite, acetylene black, conductive oxide, and conductive nitride. The content of the conductive auxiliary material may be about 0.1% by mass to 15% by mass in the total solid mass of the negative electrode material slurry. The solid content of the negative electrode material slurry means a non-volatile component in the negative electrode material slurry.

  Further, the material and shape of the current collector are not particularly limited. For example, if a belt-like material made of aluminum, copper, nickel, titanium, stainless steel or the like in a foil shape, a punched foil shape, a mesh shape, or the like is used. Good. Also, porous metal (foamed metal), carbon paper, etc., which are porous materials, can be used.

The method for applying the negative electrode material slurry to the current collector is not particularly limited. Examples of the coating method include known methods such as a metal mask printing method, electrostatic coating method, dip coating method, spray coating method, roll coating method, doctor blade method, gravure coating method, and screen printing method. After the application, it is preferable to perform a rolling process using a flat plate press, a calender roll or the like, if necessary.
Further, the integration of the negative electrode slurry and the current collector formed into a sheet shape, a pellet shape, or the like can be performed by a known method such as a roll, a press, or a combination thereof.

The negative electrode layer formed on the current collector and the negative electrode layer integrated with the current collector are preferably heat-treated under conditions according to the organic binder used. For example, when an organic binder having polyacrylonitrile as the main skeleton is used, it is preferable to perform heat treatment at 100 ° C. to 180 ° C. Further, when an organic binder having a main skeleton of polyimide or polyamideimide is used, heat treatment is preferably performed at 150 ° C. to 450 ° C.
This heat treatment increases the strength by removing the solvent and curing the binder, thereby improving the adhesion between the particles and between the particles and the current collector. Note that these heat treatments are preferably performed in an inert atmosphere such as helium, argon, nitrogen, or a vacuum atmosphere in order to prevent oxidation of the current collector during the treatment.

Further, after the heat treatment, the negative electrode is preferably pressed (pressurized). The electrode density can be adjusted by applying pressure treatment. The negative electrode for the lithium ion secondary battery, it is preferable that the electrode density of ^{1.0g / cm 3 ~2.0g / cm 3} , more to be 1.2g / cm ³ ~1.9g / cm 3 ^preferably, further preferably ^{1.4g / cm 3 ~1.8g / cm 3} . As for the electrode density, the higher the volume capacity, the better the adhesion and the cycle characteristics.

<Lithium ion secondary battery>
The lithium ion secondary battery of the present invention has the above-described negative electrode for a lithium ion secondary battery of the present invention, a positive electrode, and an electrolyte. The lithium ion secondary battery can be obtained, for example, by arranging the negative electrode for a lithium ion secondary battery and the positive electrode so as to face each other with a separator as necessary, and injecting an electrolytic solution containing an electrolyte.

  The positive electrode can be obtained by forming a positive electrode layer on the current collector surface in the same manner as the negative electrode. In this case, the current collector may be a belt-shaped member made of a metal, such as aluminum, titanium, or stainless steel, or an alloy such as a foil, a punched foil, or a mesh.

The positive electrode material used for the positive electrode layer is not particularly limited. For example, a metal compound, metal oxide, metal sulfide, or conductive polymer material that can be doped or intercalated with lithium ions may be used. It is not limited. For example, lithium cobaltate (LiCoO ₂ ), lithium nickelate (LiNiO ₂ ), lithium manganate (LiMnO ₂ ), and double oxides thereof (LiCo _x Ni _y Mn _z O ₂ , x + y + z = 1, 0 <x, 0 <y; LiNi _2-x Mn _x O ₄ , 0 <x ≦ 2), lithium manganese spinel (LiMn ₂ O ₄ ), lithium vanadium compound, V ₂ O ₅ , V ₆ O ₁₃ , VO ₂ , MnO ₂ , _{TiO 2, MoV 2 O 8,} TiS 2, V 2 S 5, VS 2, MoS 2, MoS 3, Cr 3 O 8, Cr 2 O 5, olivine-type _{LiMPO 4 (M: Co, Ni} , Mn, Fe) , Conductive polymers such as polyacetylene, polyaniline, polypyrrole, polythiophene, polyacene, porous carbon, etc. alone or in combination Can be used.

  As the separator, for example, a nonwoven fabric mainly composed of polyolefin such as polyethylene and polypropylene, cloth, microporous film, or a combination thereof can be used. In addition, when it is set as the structure where the positive electrode and negative electrode of the lithium ion secondary battery to produce are not in direct contact, it is not necessary to use a separator.

Examples of the electrolyte include lithium salts such as LiClO ₄ , LiPF ₆ , LiAsF ₆ , LiBF ₄ , LiSO ₃ CF _{3, which} are electrolytes, ethylene carbonate, propylene carbonate, butylene carbonate, vinylene carbonate, fluoroethylene carbonate, cyclopentacarbonate. Non, sulfolane, 3-methylsulfolane, 2,4-dimethylsulfolane, 3-methyl-1,3-oxazolidine-2-one, γ-butyrolactone, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, butyl methyl Carbonate, ethyl propyl carbonate, butyl ethyl carbonate, dipropyl carbonate, 1,2-dimethoxyethane, tetrahydrofuran, 2-methyltetrahydro A so-called organic electrolyte solution dissolved in a non-aqueous solvent of a simple substance such as furan, 1,3-dioxolane, methyl acetate, ethyl acetate or a mixture of two or more components can be used.

  The structure of the lithium ion secondary battery is not particularly limited. Usually, a positive electrode and a negative electrode, and a separator provided as necessary, are wound into a flat spiral shape to form a wound electrode group, In general, the electrode plates are laminated to form a laminated electrode plate group, and the electrode plate group is enclosed in an exterior body. The lithium ion secondary battery is not particularly limited, and is used as a paper-type battery, a button-type battery, a coin-type battery, a stacked battery, a cylindrical battery, a rectangular battery, or the like.

  Although the above-described negative electrode material for lithium ion secondary batteries has been described for lithium ion secondary batteries, it is also applicable to all electrochemical devices that use charging / discharging mechanisms for insertion / extraction of lithium ions, such as hybrid capacitors. It goes without saying that it is possible.

  The lithium ion secondary battery of the present invention described above is excellent in cycle characteristics, small in irreversible capacity, and excellent in safety as compared with a lithium ion secondary battery using a conventional carbon material as a negative electrode.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

Example 1
<Preparation of carbonaceous particles to be the core (raw material)>
The coal-based coal tar was heat-treated at 400 ° C. using an autoclave to obtain raw coke. After pulverizing this raw coke, it was fired (calcined) in an inert atmosphere at 1200 ° C. to obtain a coke lump. The coke mass was pulverized using an impact pulverizer equipped with a classifier, and then coarse particles were removed with a 300 mesh sieve to obtain carbonaceous particles serving as nuclei (raw materials).

<Measurement of d002 and Lc>
X-ray diffraction measurement of the carbonaceous particles obtained above was performed using a wide-angle X-ray diffractometer manufactured by Rigaku Corporation. High-purity silicon was measured as a standard substance using Cu-Kα radiation monochromatized with a monochromator. The plane spacing d002 of the 002 plane was calculated from the diffraction peak corresponding to the 002 plane appearing in the vicinity of the diffraction angle 2θ = 24 ° to 26 ° using the Bragg equation. Lc was calculated by the Scherrer equation from the half width of the diffraction peak at d002. d002 and Lc were 0.346 nm and 3.5 nm, respectively.

<Oxidation treatment of carbonaceous particles>
Thereafter, 60 g of carbonaceous particles as the core (raw material) obtained above were put into a stainless steel vat (10 cm × 6 cm × height 5.5 cm), and a muffle furnace (manufactured by ADVANTEC, model: KM-280). Was used in the atmosphere at 600 ° C. for 30 minutes to obtain an anode material of Example 1 according to the present invention. In addition, as a result of examining d002 and Lc of the negative electrode material of Example 1 in the same manner as described above, the changes were between 0.346 nm and 3.5 nm, respectively, and the carbonaceous particles serving as the nucleus (raw material). I couldn't.

<Observation of attached carbonaceous particles>
The attached carbonaceous particles adhering to the surface of the carbonaceous particles that are the negative electrode material of the present invention were examined by the following procedure using SEM. JSM-6010LA manufactured by JEOL Ltd. was used for SEM. A carbon tape was affixed to the sample folder, and a small amount of carbonaceous particles as the negative electrode material of the present invention was placed on the sample folder to prepare an observation sample. The acceleration voltage of SEM was 5 kV. In a low magnification SEM image of about 1000 times, one arbitrary carbonaceous particle having a particle diameter of 20 μm or more is selected, and then the observation magnification is set to 10000 times and the surface is relatively 10 μm × 13 μm = 130 μm ^{2 in} the region. A flat region was observed, and the number of attached carbonaceous particles having a particle size of 0.5 μm or less was examined. Further, another carbonaceous particle was selected, and the same measurement was performed for a total of five fields of view to determine the average number of attached carbonaceous particles.

<Measurement of average particle diameter>
The carbonaceous particles that are the negative electrode material of the present invention were dispersed in purified water together with a surfactant, and the solution was analyzed using a laser diffraction particle size distribution analyzer (SALD-3000J, manufactured by Shimadzu Corporation). The dispersion was placed in a water tank of the apparatus, and measurement was performed while circulating with a pump while applying ultrasonic waves. From the results of the obtained particle size distribution, the volume cumulative 50% particle size (50% D) was defined as the average particle size.

<Measurement of true specific gravity (true density)>
The true specific gravity of the carbonaceous particles as the negative electrode material of the present invention was measured by a butanol substitution method (JIS R 7212) using a specific gravity bottle.

<DTA measurement>
The DTA measurement of the carbonaceous particles, which are the negative electrode material of the present invention, was performed using a differential thermothermal gravimetric simultaneous measurement device (EXSTAR6000, manufactured by SII Nanotechnology Co., Ltd.). The heating rate was 5 ° C./min. Moreover, the measurement atmosphere was made into the air by flowing dry air. The weight of the negative electrode material of the present invention placed in a platinum sample pan was 3.0 ± 0.1 mg.

<Measurement of pH>
2.0 ± 0.2 g of carbonaceous particles as the negative electrode material of the present invention was weighed, 50 ml of pure water was added and stirred for 30 minutes. This was filtered and the pH of the filtrate was measured at 25 ° C. The pH was measured using a pH meter manufactured by Horiba, Ltd.

<Measurement of initial irreversible capacity and charge / discharge efficiency of negative electrode>
1 part by mass of carboxymethyl cellulose (CMC) and 1 part by mass of styrene-butadiene copolymer (SBR) are added to 98 parts by mass of the negative electrode material of Example 1 obtained above, and the mixture is kneaded and paste-like negative electrode material slurry. Was made. The slurry was applied to an electrolytic copper foil having a thickness of 11 μm so as to have a diameter of 9.5 mm using a mask having a thickness of 200 μm, and further dried at 105 ° C., so that a negative electrode for a monopolar test of Example 1 was produced. .

Then, after laminating the negative electrode for the single electrode test of Example 1, the separator, and the counter electrode in this order, this was mixed with ethylene carbonate (EC) and methyl ethyl carbonate (MEC) (EC and MEC are 1: 1 by volume). An electrolyte solution in which LiPF ₆ was dissolved in a solvent to a concentration of 0.5 mol / liter was injected to prepare a coin battery. Metal lithium was used for the counter electrode, and a polyethylene microporous film having a thickness of 20 μm was used for the separator.

Using the obtained coin battery, a constant current of 0.165 mA was passed between the negative electrode and the counter electrode, and charging was performed until the potential of the negative electrode with respect to the counter electrode reached 0.005 V (Vvs. Li / Li ⁺ ) (lithium was applied to the negative electrode). Occluded) and then charged at a constant voltage of 0.005 V until the current decays to 0.0165 mA. Next, after a pause of 30 minutes, discharging was performed (lithium was released from the negative electrode) at a constant current of 0.165 mA until the potential of the negative electrode with respect to the counter electrode reached 1.5 V (Vvs. Li ^/ Li ⁺ ). This charge / discharge test was performed for one cycle, and the irreversible capacity and charge / discharge efficiency in the first charge / discharge were determined. The initial irreversible capacity is the difference between the charge capacity (Ah / kg) and the discharge capacity (Ah / kg) per unit weight of the negative electrode material, and the initial charge / discharge efficiency is (discharge capacity) / (charge capacity) × 100 (%) Calculated. The results are shown in Table 2.

<Evaluation of life characteristics of lithium ion secondary battery>
To 98 parts by mass of the negative electrode material of Example 1, 1 part by mass of carboxymethyl cellulose (CMC) and 1 part by mass of styrene-butadiene copolymer (SBR) were added and kneaded to prepare a paste-like negative electrode material slurry. This slurry was applied to an electrolytic copper foil having a thickness of 11 μm using a coating machine so that the coating amount per unit area was 4.5 mg / cm ² , then dried at 105 ° C., and further, using a roll press machine. The negative electrode for the lithium ion secondary battery of Example 1 was produced by compression molding so that the density of the negative electrode material layer was 1.05 g / cm ³ .

Further, LiMn ₂ O ₄ having a particle size of 5 μm was used as the positive electrode active material, and 5 parts by mass of acetylene black and 5 parts by mass of polyvinylidene fluoride (PVDF) were added to 90 parts by mass of the positive electrode active material, and kneaded. A positive electrode material slurry was prepared. This slurry was applied to an electrolytic aluminum foil having a thickness of 20 μm using a coating machine so that the coating amount per unit area was 11.1 mg / cm ² , then dried at 105 ° C., and a positive electrode material using a roll press machine. The positive electrode for the lithium ion secondary battery of Example 1 was produced by compression molding so that the layer density was 2.5 g / cm ³ .

Next, a negative electrode, a separator, and a positive electrode were stacked in this order and set in a coin cell container. An electrolyte solution in which LiPF ₆ was dissolved in a mixed solvent of ethylene carbonate (EC) and methyl ethyl carbonate (MEC) (EC and MEC are 1: 1 by volume) to a concentration of 1.0 mol / liter. 3 ml was injected, and the coin cell container was caulked to produce a coin cell type lithium ion secondary battery of the present invention.

  Using this coin cell type lithium ion secondary battery of the present invention, the battery was charged to 4.15 V at a constant current of 4.38 mA in a constant temperature bath at 25 ° C., and the current was further reduced to 0.438 mA at a constant voltage of 4.15 V. Charged until Then, after a 30-minute pause, discharging was performed to 2.5 V at a constant current of 4.38 mA. Furthermore, a rest of 30 minutes was provided thereafter, which was defined as one cycle. The discharge capacity retention rate for the first cycle when this cycle was repeated 250 times was measured, and the life characteristics were evaluated. The results are shown in Table 2.

(Example 2)
Commercially available coke having d002 of 0.346 nm and Lc of 5.2 nm was pulverized using an impact pulverizer equipped with a classifier, and then coarse particles were removed with a 300 mesh sieve to remove the core (raw material). Carbonaceous particles were obtained. Thereafter, the carbonaceous particles were oxidized in the same manner as in Example 1 to obtain a negative electrode material of Example 2 according to the present invention. Further, using the negative electrode material of Example 2, as in Example 1, observation of adhered carbonaceous particles, measurement of average particle diameter, measurement of true specific gravity (true density), DTA measurement, pH measurement, negative electrode The first irreversible capacity, the measurement of charge / discharge efficiency, and the life characteristics of the lithium ion secondary battery were evaluated. The results are shown in Table 2.

Example 3
The negative electrode material of Example 3 according to the present invention having a different particle size distribution was prepared in the same manner as in Example 2 except that the classification conditions of the impact pulverizer with a classifier in Example 2 were changed (the number of revolutions was reduced). Obtained. Further, using the negative electrode material of Example 3, in the same manner as in Example 1, observation of adhered carbonaceous particles, measurement of average particle diameter, measurement of true specific gravity (true density), DTA measurement, pH measurement, negative electrode The irreversible capacity, the initial charge / discharge efficiency, and the life characteristics of the lithium ion secondary battery were evaluated. The results are shown in Table 2.

Example 4
The negative electrode material of Example 4 according to the present invention having a different particle size distribution was prepared in the same manner as in Example 2 except that the classification conditions of the impact pulverizer with a classifier in Example 2 were changed (increase in the number of revolutions). Obtained. Further, using the negative electrode material of Example 4, as in Example 1, observation of adhered carbonaceous particles, measurement of average particle diameter, measurement of true specific gravity (true density), DTA measurement, pH measurement, negative electrode The irreversible capacity, the initial charge / discharge efficiency, and the life characteristics of the lithium ion secondary battery were evaluated. The results are shown in Table 2.

(Example 5)
A commercially available coke having a d002 of 0.347 nm and an Lc of 3.9 nm was pulverized using an impact pulverizer equipped with a classifier, and then coarse particles were removed with a 300-mesh sieve to obtain a core (raw material). Carbonaceous particles were obtained. Thereafter, the present invention was carried out in the same manner as in Example 1 except that the muffle furnace temperature was changed to 650 ° C. and the processing time was changed to 15 minutes in the processing conditions of the oxidation treatment of the carbonaceous particles of Example 1. The negative electrode material of Example 5 was obtained. Further, using the negative electrode material of Example 5, in the same manner as in Example 1, observation of attached carbonaceous particles, measurement of average particle diameter, measurement of true specific gravity (true density), DTA measurement, pH measurement, negative electrode The first irreversible capacity, the measurement of charge / discharge efficiency, and the life characteristics of the lithium ion secondary battery were evaluated. The results are shown in Table 2.

Example 6
Using commercially available coke with d002 of 0.345 nm and Lc of 4.9 nm, this was pulverized using an impact pulverizer equipped with a classifier, and then coarse particles were removed with a 300 mesh sieve to obtain a core (raw material) Carbonaceous particles were obtained. Then, it carried out similarly to Example 5, and obtained the negative electrode material of Example 6 which is this invention. Further, using the negative electrode material of Example 6, in the same manner as in Example 1, observation of attached carbonaceous particles, measurement of average particle diameter, measurement of true specific gravity (true density), DTA measurement, pH measurement, negative electrode The first irreversible capacity, the measurement of charge / discharge efficiency, and the life characteristics of the lithium ion secondary battery were evaluated. The results are shown in Table 2.

(Comparative Example 1)
The carbonaceous particles used as the core (raw material) produced in Example 1 were used as the negative electrode material of Comparative Example 1 as they were. Thereafter, in the same manner as in Example 1, observation of adhered carbonaceous particles, measurement of average particle diameter, measurement of true specific gravity (true density), DTA measurement, measurement of pH, initial irreversible capacity of negative electrode, measurement of charge / discharge efficiency The life characteristics of the lithium ion secondary battery were evaluated. The results are shown in Table 2.

<Observation results of attached carbonaceous particles>
1A to 1C show SEM images of the negative electrode material of Example 1 at 1000 times (FIG. 1A), 5000 times (FIG. 1B), and 10000 times (FIG. 1C). First, observation was performed at a low magnification of 1000 times, and particles having a size of 20 μm or more were arbitrarily selected from the visual field. The relatively flat portion of the particles was magnified up to 10000 times to confirm the number of attached carbonaceous particles attached. In this example, the field of view of the 10,000-times SEM image corresponds to a region of 10 μm × 13 μm = 130 μm ² , and the number of attached carbonaceous particles having a particle diameter of 0.5 μm or less was counted in this region. Furthermore, another carbonaceous particle was selected, and the same measurement was performed for a total of five fields of view 1 to field of view 5. FIG. 2A to FIG. 2E show SEM images of a total of five fields of fields 1 to 5 observed at 10000 times. In FIG. 2A to FIG. 2E, white circle marks are added to the places of the attached carbonaceous particles having a particle diameter of 0.5 μm or less. Table 1 shows the number of each field of the attached carbonaceous particles adhering to the region of 130 μm ² counted by the above procedure and the average value thereof.

3A to 3C show SEM images of the negative electrode material of Comparative Example 1 at 1000 times (FIG. 3A), 5000 times (FIG. 3B), and 10000 times (FIG. 3C). First, observation was performed at a low magnification of 1000 times, and particles having a size of 20 μm or more were arbitrarily selected from the visual field. A relatively flat portion of the particles was magnified up to 10,000 times, and the number of adhering carbonaceous particles adhered was confirmed in the same manner as described above. Furthermore, another carbonaceous particle was selected, and the same measurement was performed for a total of five fields of view 1 to field of view 5. FIG. 4A to FIG. 4E show SEM images of a total of five fields, that is, fields 1 to 5 observed at a magnification of 10,000. In FIG. 4A to FIG. 4E, white circle marks are added to the places of the attached carbonaceous particles having a particle diameter of 0.5 μm or less. Table 1 shows the number of each field of the attached carbonaceous particles adhering to the region of 130 μm ² counted by the above procedure and the average value thereof.

  Observation of the above adhering carbonaceous particles was also performed for Examples 2-6. The results are shown in Table 1. When Examples 1-6 are compared with Comparative Example 1, it can be seen that the number of attached carbonaceous particles has been greatly reduced by the oxidation treatment.

  In Table 2, the characteristic of the negative electrode material produced in Examples 1-6 and the comparative example 1 and the characteristic of a lithium ion secondary battery are shown.

  As shown in Table 2, in comparison with Comparative Example 1, the negative electrodes of Examples 1 to 6 had small initial cycle irreversible capacity, high initial charge / discharge efficiency, and excellent characteristics. Furthermore, compared with the lithium ion secondary battery of Comparative Example 1, it was found that the lithium ion secondary batteries of Examples 1 to 6 had a higher capacity retention rate after 200 cycles and a longer life.

  In the negative electrode materials of Examples 1 to 6, the oxidation treatment in the atmosphere was performed to reduce the attached carbonaceous particles, and the reaction with the electrolyte solution on the negative electrode material surface was suppressed, so the initial irreversible capacity of the negative electrode decreased and decreased. It is considered that the initial charge / discharge efficiency was improved and the life of the lithium ion secondary battery was improved.

From the above results, it was found that the negative electrode to which the negative electrode material for a lithium ion secondary battery of the present invention and the lithium ion secondary battery were applied were excellent in charge / discharge efficiency, life characteristics, and balance thereof.

Claims (9)

The surface distance d002 of the 002 plane determined by X-ray diffractometer (XRD) measurement is 0.340 nm or more and 0.370 nm or less, and the particle diameter exceeds 0.5 μm. deposited, comprising: a deposition carbonaceous particles having a particle diameter of 0.5μm or less, the adhesion speed of the deposited carbonaceous particles, Ri surface area 130 .mu.m ² per 0 der 50 or less than the said carbonaceous particles , the type and the attachment carbonaceous particles of type a negative electrode material for lithium ion secondary batteries to be the same as of the carbonaceous particles. The surface distance d002 of the 002 plane determined by X-ray diffractometer (XRD) measurement is 0.340 nm or more and 0.370 nm or less, and the particle diameter exceeds 0.5 μm. Adhering carbonaceous particles having a particle diameter of 0.5 μm or less, and the adhering number of adhering carbonaceous particles exceeds 0.0 / μm ² per unit surface area of the carbonaceous particles. 4 / [mu] m ² Ri der hereinafter, the type and the attachment carbonaceous particles of type a negative electrode material for lithium ion secondary batteries to be the same as of the carbonaceous particles.   The negative electrode material for a lithium ion secondary battery according to claim 1 or 2, wherein a crystallite size (Lc) in the c-axis direction of the carbonaceous particles is 3.3 nm or more and 5.5 nm or less.   The lithium according to any one of claims 1 to 3, wherein when dispersed in pure water so as to have a concentration of 3.8% by mass, the pH at 25 ° C is 5.6 or more and 6.1 or less. Negative electrode material for ion secondary battery.   5. The differential thermal analysis (DTA) measurement at a heating rate of 5 ° C./min in an air atmosphere has a DTA peak at 650 ° C. or more and 680 ° C. or less according to claim 1. The negative electrode material for lithium ion secondary batteries as described. The volume average particle diameter (50% D) is 5 μm or more and 30 μm or less, and the true specific gravity is 1.8 g / cm ³ or more and 2.2 g / cm ³ or less. The negative electrode material for lithium ion secondary batteries as described. A current collector,
A negative electrode material layer disposed on the current collector and including the negative electrode material for a lithium ion secondary battery according to any one of claims 1 to 6,
A negative electrode for a lithium ion secondary battery.   The lithium ion secondary battery containing the negative electrode for lithium ion secondary batteries of Claim 7, a positive electrode, and electrolyte. A step of obtaining a pulverized product by pulverizing carbonaceous particles having a 002 plane distance d002 of 0.340 nm or more and 0.370 nm or less determined by X-ray diffractometer (XRD) measurement;
The method for producing a negative electrode material for a lithium ion secondary battery according to any one of claims 1 to 6, comprising a step of heat-treating the pulverized product at 400 ° C to 700 ° C in an air atmosphere. .