JP2015179666A - Carbonaceous material for nonaqueous electrolyte secondary battery, method of manufacturing the same, negative electrode for nonaqueous electrolyte secondary battery, and nonaqueous electrolyte secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a carbonaceous material for a non-aqueous electrolyte secondary battery having excellent charge/discharge capacity and also excellent durability to oxidation degradation, and also to provide a method of manufacturing the same, a negative electrode for the non-aqueous electrolyte secondary battery and the non-aqueous electrolyte secondary battery.SOLUTION: A method of manufacturing a carbonaceous material for a non-aqueous electrolyte secondary battery, which includes a step for obtaining the carbonaceous material by calcinating a mixture between a carbon precursor having a specific surface area of 100 to 500 m/g and a volatile organic substance under an inert gas atmosphere of 800 to 1400°C. The carbon precursor is obtained by, for example, decalcifying plant-derived char.

Description

  The present invention relates to a carbonaceous material suitable for a negative electrode of a nonaqueous electrolyte secondary battery represented by a lithium ion secondary battery, a method for producing the same, a negative electrode for a nonaqueous electrolyte secondary battery, and a nonaqueous electrolyte secondary battery.

  Lithium ion secondary batteries are widely used in small portable devices such as mobile phones and laptop computers. As a negative electrode material for a lithium ion secondary battery, non-graphitizable carbon capable of doping (charging) and dedoping (discharging) lithium in an amount exceeding the theoretical capacity of 372 mAh / g of graphite has been developed (for example, Patent Document 1). ), Have been used.

  The non-graphitizable carbon can be obtained using, for example, petroleum pitch, coal pitch, phenol resin, or plant as a carbon source. Among these carbon sources, plants are attracting attention because they are raw materials that can be continuously and stably supplied by cultivation and can be obtained at low cost. Moreover, since the carbonaceous material obtained by baking a plant-derived carbon raw material has many pores, a favorable charge / discharge capacity is expected (for example, Patent Document 1 and Patent Document 2).

  On the other hand, in recent years, due to increasing interest in environmental problems, development of lithium ion secondary batteries for in-vehicle applications has been promoted and is being put to practical use.

JP-A-9-161801 JP-A-10-21919

  In particular, a carbonaceous material used for a lithium ion battery for in-vehicle use is required to have a good charge / discharge capacity and further resistance to oxidative degradation.

  Accordingly, an object of the present invention is to provide a carbonaceous material (non-aqueous electrolyte secondary) used for a negative electrode of a non-aqueous electrolyte secondary battery (for example, a lithium ion secondary battery) that has good charge / discharge capacity and good resistance to oxidative degradation. Another object is to provide a method for producing a carbonaceous material for a secondary battery.

The inventors have
A step of firing a mixture of a carbon precursor having a specific surface area of 100 to 500 m ² / g and a volatile organic substance in an inert gas atmosphere at 800 to 1400 ° C. to obtain a carbonaceous material;
Comprising
It has been found that the above object can be achieved by a carbonaceous material for a nonaqueous electrolyte secondary battery obtained by the method for producing a carbonaceous material for a nonaqueous electrolyte secondary battery and the production method of the present invention.
That is, the present invention includes the following preferred embodiments.
[1] A step of baking a mixture of a carbon precursor having a specific surface area of 100 to 500 m ² / g and a volatile organic substance in an inert gas atmosphere at 800 to 1400 ° C. to obtain a carbonaceous material,
Comprising
A method for producing a carbonaceous material for a non-aqueous electrolyte secondary battery.
[2] The method for producing a carbonaceous material for a nonaqueous electrolyte secondary battery according to [1], wherein the carbon precursor is derived from a plant.
[3] The production of the carbonaceous material for a non-aqueous electrolyte secondary battery according to [1] or [2], wherein the volatile organic substance is in a solid state at room temperature and has a residual carbon ratio of less than 5% by weight. Method.
[4] are calculated using the Bragg equation by wide angle X-ray diffraction method, the average spacing _{d 002} of (002) plane of the carbonaceous material for the nonaqueous electrolyte battery is in the range of 0.36~0.42nm The nonaqueous electrolyte according to any one of [1] to [3], wherein a specific surface area of the carbonaceous material for a nonaqueous electrolyte battery determined by a nitrogen adsorption BET three-point method is in the range of 1 to ²⁰ m ² / g. A method for producing a carbonaceous material for a secondary battery.
[5] The average spacing d ₀₀₂ of the (002) plane is in the range of 0.38 to 0.40 nm, and the specific surface area is in the range of 1 to 10 m ² / g. A method for producing a carbonaceous material for a water electrolyte secondary battery.
[6] The volatile organic material is at least one selected from the group consisting of polystyrene, polyethylene, polypropylene, poly (meth) acrylic acid, poly (meth) acrylic ester, naphthalene, phenanthrene, anthracene, and pyrene. The manufacturing method of the carbonaceous material for nonaqueous electrolyte secondary batteries in any one of said [1]-[5].
[7] (1) Gas phase deashing step including heat-treating plant-derived char at 500 ° C. to 940 ° C. in an inert gas atmosphere containing a halogen compound,
(2) a mixing step of obtaining a mixture comprising char derived from gas phase decalcified and a volatile organic substance having a residual carbon ratio of less than 5% by weight when incinerated at 800 ° C., and (3) The manufacturing method of the carbonaceous material for nonaqueous electrolyte secondary batteries in any one of said [1]-[6] including the process of baking a mixture.
[8] The non-aqueous electrolyte 2 according to [7] above, wherein a weight ratio of the vapor-decalcified plant-derived char and the volatile organic substance in the mixture is 97: 3 to 40:60. Manufacturing method of carbonaceous material for secondary battery.
[9] The firing is
The non-aqueous solution according to [7] or [8], which is (a) main baking at 800 to 1600 ° C, or (b) preliminary baking at 350 to less than 800 ° C, and main baking at 800 to 1600 ° C. A method for producing a carbonaceous material for an electrolyte secondary battery.
[10] The average interplanar spacing d ₀₀₂ of the (002) plane of the carbonaceous material for nonaqueous electrolyte batteries, calculated using the Bragg equation by wide-angle X-ray diffraction, is in the range of 0.36 to 0.42 nm. The specific surface area of the carbonaceous material for a non-aqueous electrolyte battery determined by the nitrogen adsorption BET three-point method is in the range of 1 to ²⁰ m ² / g, the nitrogen element content is 0.5% by weight or less, and the oxygen element content is 0. A carbonaceous material for a non-aqueous electrolyte secondary battery that is 25% by weight or less.
[11] The non-facet according to [10], wherein an average interplanar spacing d ₀₀₂ of the (002) plane is in a range of 0.38 to 0.40 nm, and the specific surface area is in a range of 1 to 10 m ² / g. Carbonaceous material for water electrolyte secondary batteries.
[12] The carbonaceous material for a non-aqueous electrolyte secondary battery is obtained by firing a mixture of a carbon precursor having a specific surface area of 100 to 500 m ² / g and a volatile organic substance in an inert gas atmosphere at 800 to 1400 ° C. The carbonaceous material for a non-aqueous electrolyte secondary battery according to [10] or [11].
[13] The carbonaceous material for a nonaqueous electrolyte secondary battery according to [12], wherein the carbon precursor is derived from a plant.
[14] The volatile organic material is at least one selected from the group consisting of polystyrene, polyethylene, polypropylene, poly (meth) acrylic acid, poly (meth) acrylic acid ester, naphthalene, phenanthrene, anthracene, and pyrene. The carbonaceous material for a nonaqueous electrolyte secondary battery according to the above [12] or [13].
[15] The carbon for nonaqueous electrolyte secondary batteries according to any one of [10] to [14], wherein the potassium element content is 0.1% by weight or less and the iron element content is 0.02% by weight or less. Quality material.
[16] The carbonaceous material for a nonaqueous electrolyte secondary battery according to any one of [10] to [15], wherein a true density determined by a butanol method is 1.40 to 1.70 g / cm ³ .
[17] A negative electrode for a non-aqueous electrolyte secondary battery comprising the carbonaceous material for a non-aqueous electrolyte secondary battery according to any one of [10] to [16].
[18] A non-aqueous electrolyte secondary battery including the negative electrode for a non-aqueous electrolyte secondary battery according to [17].

  According to the method for producing a carbonaceous material for a nonaqueous electrolyte secondary battery of the present invention, a carbonaceous material for a nonaqueous electrolyte secondary battery having a good charge / discharge capacity and a good resistance to oxidative degradation is easily produced. be able to.

  The following is an explanation of an embodiment of the present invention, and is not intended to limit the present invention to the following embodiment. In addition, in this specification, normal temperature refers to 25 degreeC.

(Carbonaceous material for non-aqueous electrolyte secondary batteries)
The carbonaceous material for a non-aqueous electrolyte secondary battery according to the present embodiment is obtained by firing a mixture of a carbon precursor and a volatile organic substance in an inert gas atmosphere at 800 to 1400 ° C.

  A carbon precursor is a precursor of a carbonaceous material that supplies a carbon component when producing a carbonaceous material, and uses a plant-derived carbon material (hereinafter sometimes referred to as “plant-derived char”) as a raw material. Can be used. In addition, char generally indicates a powder-like solid rich in carbon that is not melt-softened, which is obtained when coal is heated, but here it is rich in carbon that is not melt-softened obtained by heating organic matter. Also shown is a powdered solid.

  There are no particular restrictions on the plant (hereinafter sometimes referred to as “plant material”) that is the raw material for plant-derived char. For example, coconut husks, coconut beans, tea leaves, sugar cane, fruits (eg, mandarin oranges, bananas), cocoons, rice husks, hardwoods, conifers, and bamboo can be exemplified. Examples of this include waste (for example, used tea leaves) after being used for the original use, or part of plant materials (for example, bananas and tangerine peels). These plants can be used alone or in combination of two or more. Among these plants, coconut shells that are easily available in large quantities are preferred.

  The coconut shell is not particularly limited, and examples thereof include palm palm (oil palm), coconut palm, salak, and palm palm. These coconut shells can be used alone or in combination. Coconut palm and palm palm coconut shells, which are biomass wastes that are used as foods, detergent raw materials, biodiesel oil raw materials and the like and are generated in large quantities, are particularly preferred.

  The method for producing char from the plant raw material is not particularly limited. For example, the plant raw material is heat-treated (hereinafter sometimes referred to as “temporary firing”) in an inert gas atmosphere of 300 ° C. or higher. Can be manufactured by.

  It can also be obtained in the form of char (eg, coconut shell char).

  A carbonaceous material produced from plant-derived char can be doped with a large amount of active material, and thus is basically suitable as a negative electrode material for a non-aqueous electrolyte secondary battery. However, plant-derived char contains a large amount of metal elements contained in plants. For example, coconut shell char contains about 0.3% potassium and about 0.1% iron element. If a carbonaceous material containing a large amount of such metal elements is used as the negative electrode, it may adversely affect the electrochemical characteristics and safety of the nonaqueous electrolyte secondary battery.

  The plant-derived char also contains alkali metals other than potassium (for example, sodium), alkaline earth metals (for example, magnesium, calcium), transition metals (for example, iron, copper) and other metals. If the carbonaceous material contains these metals, impurities may elute into the electrolyte during dedoping from the negative electrode of the non-aqueous electrolyte secondary battery, which may adversely affect battery performance and harm safety. is there.

  Furthermore, it has been confirmed by the inventors that the pores of the carbonaceous material are blocked by ash, which may adversely affect the charge / discharge capacity of the battery.

  Therefore, such ash (alkali metal, alkaline earth metal, transition metal, and other elements) contained in plant-derived char is deashed before firing to obtain a carbonaceous material. It is desirable to reduce the ash content. The deashing method is not particularly limited. For example, a method (liquid phase deashing) in which a metal component is extracted and deashed using acid water containing a mineral acid such as hydrochloric acid or sulfuric acid, or an organic acid such as acetic acid or formic acid, hydrogen chloride A method of deashing by exposing to a high temperature gas phase containing a halogen compound such as (gas phase deashing) can be used. Although not intended to limit the deashing method to be applied, gas phase deashing that is preferable in that no drying process is required after deashing will be described below. The decalcified plant-derived char is hereinafter also referred to as “plant-derived char carbon precursor”.

  As the gas phase decalcification, it is preferable to heat-treat the plant-derived char in a gas phase containing a halogen compound. The halogen compound is not particularly limited. For example, fluorine, chlorine, bromine, iodine, hydrogen fluoride, hydrogen chloride, hydrogen bromide, iodine bromide, chlorine fluoride (ClF), iodine chloride (ICl), iodine bromide ( IBr), bromine chloride (BrCl) and the like. A compound that generates these halogen compounds by thermal decomposition, or a mixture thereof can also be used. From the viewpoint of supply stability and stability of the halogen compound used, hydrogen chloride is preferred.

  The vapor phase deashing may be used by mixing a halogen compound and an inert gas. The inert gas is not particularly limited as long as it is a gas that does not react with the carbon component constituting the plant-derived char. For example, nitrogen, helium, argon, krypton, or a mixed gas thereof can be given. From the viewpoint of supply stability and economy, nitrogen is preferred.

  In the gas phase deashing, the mixing ratio of the halogen compound and the inert gas is not limited as long as sufficient deashing can be achieved. For example, safety, economy, and persistence in carbon From the viewpoint, the amount of the halogen compound with respect to the inert gas is preferably 0.01 to 10.0% by volume, more preferably 0.05 to 8.0% by volume, and still more preferably 0.1 to 5.%. 0% by volume.

  The temperature of the vapor phase demineralization may be changed depending on the plant-derived char which is the object of demineralization, but from the viewpoint of obtaining a desired nitrogen content and oxygen content, for example, 500 to 950 ° C, preferably 600 to 940 ° C, More preferably, it is 650-940 degreeC, More preferably, it can implement at 850-930 degreeC. When the deashing temperature is too low, the deashing efficiency is lowered and the deashing may not be sufficiently performed. If the deashing temperature is too high, activation by a halogen compound may occur.

  The time for the vapor phase deashing is not particularly limited, but is, for example, 5 to 300 minutes, preferably 10 to 200 minutes, from the viewpoint of the economic efficiency of the reaction equipment and the structure retention of carbon. More preferably, it is 20 to 150 minutes.

  The vapor phase decalcification in this embodiment is to remove potassium, iron and the like contained in plant-derived char. The potassium content contained in the carbon precursor obtained after the vapor phase deashing treatment is preferably 0.1% by weight or less from the viewpoint of increasing the dedoping capacity and decreasing the non-dedoping capacity, and is 0.05% by weight. % Or less is more preferable, and 0.03% by weight or less is more preferable. The iron content contained in the carbon precursor obtained after the vapor phase deashing treatment is preferably 0.02% by weight or less from the viewpoint of increasing the dedoping capacity and decreasing the non-dedoping capacity, and 0.015% by weight. % Or less is more preferable, and 0.01% by weight or less is more preferable. When the content of potassium or iron contained in the carbon precursor is increased, the dedoping capacity may be reduced in the nonaqueous electrolyte secondary battery using the obtained carbonaceous material. Also, the undedoped capacity may increase. Furthermore, a short circuit may occur when these metal elements are eluted and re-deposited in the electrolytic solution, which may cause a serious problem in the safety of the nonaqueous electrolyte secondary battery. It is particularly preferred that the plant-derived char carbon precursor after vapor phase decalcification does not substantially contain potassium element and iron element. The details of the measurement of the content of potassium element and iron element are as described in Examples, and a fluorescent X-ray analyzer (for example, “LAB CENTER XRF-1700” manufactured by Shimadzu Corporation) can be used.

  The particle diameter of the plant-derived char that is subject to vapor phase demineralization is not particularly limited. However, if the particle diameter is too small, the gas phase containing removed potassium and the like and the plant-derived char Since it may be difficult to separate, the lower limit of the average particle diameter is preferably 100 μm or more, more preferably 300 μm or more, and even more preferably 500 μm or more. In addition, the upper limit of the average value of the particle diameter is preferably 10,000 μm or less, more preferably 8000 μm or less, and still more preferably 5000 μm or less from the viewpoint of fluidity in a mixed gas stream. Here, the details of the measurement of the particle diameter are as described in Examples, and for example, a particle size distribution measuring instrument (for example, “SALD-3000S” manufactured by Shimadzu Corporation) can be used by a laser diffraction method.

  The apparatus used for vapor phase demineralization is not particularly limited as long as it can be heated while mixing plant-derived char and a vapor phase containing a halogen compound. For example, using a fluidized furnace, a continuous type or a batch type in-bed flow method using a fluidized bed or the like can be used. The supply amount (flow rate) of the gas phase is not particularly limited, but from the viewpoint of fluidity in the mixed gas stream, for example, preferably 1 ml / min or more, more preferably 5 ml / min or more, per 1 g of plant-derived char. Preferably, a gas phase of 10 ml / min or more is supplied.

  In vapor phase deashing, after heat treatment in an inert gas atmosphere containing a halogen compound (hereinafter sometimes referred to as “halogen heat treatment”), further heat treatment in the absence of a halogen compound (hereinafter referred to as “vapor phase”). It is preferable to perform “deoxidation treatment”. Since halogen is contained in the plant-derived char by the halogen heat treatment, it is preferable to remove the halogen contained in the plant-derived char by gas phase deoxidation treatment. Specifically, the gas-phase deoxidation treatment is performed in an inert gas atmosphere containing no halogen compound at 500 ° C. to 940 ° C., preferably 600 to 940 ° C., more preferably 650 to 940 ° C., and still more preferably 850 to 930. The heat treatment is performed at a temperature of 0 ° C., and the temperature of the heat treatment is preferably the same as or higher than the temperature of the first heat treatment. For example, after the halogen heat treatment, the halogen can be removed by shutting off the supply of the halogen compound and performing the heat treatment. Further, the time for the vapor phase deoxidation treatment is not particularly limited, but is preferably 5 minutes to 300 minutes, more preferably 10 minutes to 200 minutes, and further preferably 10 minutes to 100 minutes. .

  The carbon precursor is adjusted in average particle size through a pulverization step and a classification step as necessary. The pulverization step and the classification step are preferably performed after the decalcification treatment.

In the pulverization step, the carbon precursor is preferably pulverized so that the average particle size after the firing step is in the range of, for example, 3 to 30 μm, from the viewpoint of coatability during electrode production. That is, the average particle diameter (Dv ₅₀ ) of the carbonaceous material of the present embodiment is prepared to be in the range of 3 to 30 μm, for example. If the average particle size is less than 3 μm, the fine powder increases, the specific surface area increases, the reactivity with the electrolyte increases, the irreversible capacity that does not discharge even when charged increases, and the capacity of the positive electrode is wasted May increase. Moreover, when a negative electrode is manufactured using the obtained carbonaceous material, the space | gap formed between carbonaceous materials will become small and the movement of the lithium ion in electrolyte solution may be suppressed. The average particle diameter (Dv ₅₀ ) of the carbonaceous material of the present invention is preferably 3 μm or more, more preferably 4 μm or more, and further preferably 5 μm or more. On the other hand, when the average particle size is 30 μm or less, it is preferable because the lithium ion diffusion free process in the particles is small and rapid charge / discharge is possible. Further, in the lithium ion secondary battery, it is important to increase the electrode area for improving the input / output characteristics. For this reason, it is necessary to reduce the coating thickness of the active material on the current collector plate during electrode preparation. In order to reduce the coating thickness, it is necessary to reduce the particle diameter of the active material. From such a viewpoint, the average particle size is preferably 30 μm or less, more preferably 19 μm or less, still more preferably 17 μm or less, particularly preferably 16 μm or less, and most preferably 15 μm or less. .

  In addition, the plant-derived char carbon precursor shrinks by about 0 to 20% depending on the conditions of the main firing described later. Therefore, in order for the average particle size after firing to be 3 to 30 μm, the average particle size of the plant-derived char carbon precursor is about 0 to 20% larger than the desired average particle size after firing. It is preferable to prepare so that it may become a particle system. Therefore, the average particle size after pulverization is preferably 3 to 36 μm, more preferably 3 to 22.8 μm, still more preferably 3 to 20.4 μm, particularly preferably 3 to 19.2 μm, and most preferably 3 to 18 μm. It is preferable to perform pulverization.

  Since the carbon precursor does not dissolve even when the heat treatment step described later is performed, the order of the pulverization step is not particularly limited as long as it is after the decalcification step. From the viewpoint of reducing the specific surface area of the carbonaceous material, it is preferably performed before the firing step. This is because the specific surface area may not be sufficiently reduced when plant-derived char is pulverized after being mixed with volatile organic matter and fired. However, it does not exclude performing the pulverization step after the firing step.

  The pulverizer used in the pulverization step is not particularly limited, and for example, a jet mill, a ball mill, a hammer mill, or a rod mill can be used. From the viewpoint of generating less fine powder, a jet mill having a classification function is preferable. When using a ball mill, a hammer mill, a rod mill or the like, fine powder can be removed by classification after the pulverization step.

  The classification step makes it possible to prepare the average particle diameter of the carbonaceous material more accurately. For example, particles having a particle diameter of 1 μm or less can be removed.

  When particles having a particle diameter of 1 μm or less are removed by classification, it is preferable that the content of particles having a particle diameter of 1 μm or less is 3% by volume or less in the carbonaceous material for a non-aqueous electrolyte secondary battery of the present invention. The removal of particles having a particle diameter of 1 μm or less is not particularly limited as long as it is after pulverization, but it is preferable to carry out the pulverization simultaneously with the powder classification. In the carbonaceous material for a non-aqueous electrolyte secondary battery of the present invention, the content of particles having a particle size of 1 μm or less is preferably 3% by volume or less from the viewpoint of reducing the specific surface area and irreversible capacity. More preferably, it is 5 volume% or less, and it is still more preferable that it is 2.0 volume% or less.

  The classification method is not particularly limited, and examples thereof include classification using a sieve, wet classification, and dry classification. As the wet classifier, for example, a classifier using principles such as gravity classification, inertia classification, hydraulic classification, centrifugal classification, and the like can be given. Examples of the dry classifier include a classifier using a principle such as sedimentation classification, mechanical classification, and centrifugal classification.

  The pulverization step and the classification step can be performed using one apparatus. For example, the pulverization step and the classification step can be performed using a jet mill having a dry classification function. Furthermore, an apparatus in which the pulverizer and the classifier are independent can be used. In this case, pulverization and classification can be performed continuously, but pulverization and classification can also be performed discontinuously.

In the present embodiment, the specific surface area of the carbon precursor after the pulverization is 100 to 500 m ² / g, and preferably is 200 to 500 m ² / g, for example 200 to 400 m ² / g. If the specific surface area is too small, the fine pores of the carbonaceous material may not be sufficiently reduced even after the firing step described later, and the hygroscopicity of the carbonaceous material may be difficult to decrease. When water is present in the carbonaceous material, the generation of acid accompanying the hydrolysis of the electrolyte and the generation of gas due to the electrolysis of water may cause problems. Further, the oxidation of the carbonaceous material proceeds under an air atmosphere, and the battery performance may change greatly. If the specific surface area becomes too large, the specific surface area of the carbonaceous material will not be reduced even after the firing step described later, and the utilization efficiency of lithium ions in the nonaqueous electrolyte secondary battery may be reduced. The specific surface area of the carbon precursor can be prepared by controlling the temperature of vapor phase demineralization. In the present specification, the specific surface area means a specific surface area (BET specific surface area) determined by a BET method (nitrogen adsorption BET three-point method). Specifically, it can measure using the method mentioned later.

The method for producing the carbonaceous material for a non-aqueous electrolyte secondary battery of the present embodiment is as follows:
A step of firing a mixture of a carbon precursor having a specific surface area of 100 to 500 m ² / g and a volatile organic substance in an inert gas atmosphere at 800 to 1400 ° C. to obtain a carbonaceous material (hereinafter referred to as “firing step”). Is provided). The firing step is preferably performed after the decalcification step, and is preferably performed after the decalcification step, the pulverization step, and the classification step.

  By baking the mixture of the carbon precursor and the volatile organic substance, the carbonaceous material of the present embodiment is obtained. By mixing and firing a carbon precursor and a volatile organic material, the specific surface area of the resulting carbonaceous material can be reduced, and the specific surface area suitable for a negative electrode material for a non-aqueous electrolyte secondary battery Can do. Furthermore, the amount of carbon dioxide adsorbed on the carbonaceous material can be adjusted.

  Although the mechanism by which the specific surface area of the carbonaceous material for nonaqueous electrolyte secondary batteries of the present invention is reduced has not been elucidated in detail, it can be considered as follows. However, the present invention is not limited by the following description. It is thought that a carbonaceous film obtained by heat treatment of volatile organic substances is formed on the surface of plant-derived char carbon precursors by mixing and firing plant-derived char carbon precursors and volatile organic substances. It is done. This carbonaceous coating reduces the specific surface area of the carbonaceous material produced from plant-derived char carbon precursors and suppresses the formation reaction of a coating called SEI (Solid Electrolyte Interphase) due to the reaction between the carbonaceous material and lithium. Therefore, it can be expected to reduce the irreversible capacity. Moreover, since the produced carbonaceous film can also dope and dedope lithium, the effect of increasing the capacity can be expected.

The volatile organic substance is preferably an organic substance having a residual carbon ratio of less than 5%, and is preferably an organic substance having a residual carbon ratio of less than 5% when incinerated at 800 ° C. The volatile organic substance is preferably one that generates a volatile substance (for example, hydrocarbon gas or tar) that can reduce the specific surface area of a carbon precursor produced from plant-derived char. In addition, in the volatile organic substance, the content of the volatile substance (for example, hydrocarbon gas or tar component) that can reduce the specific surface area is not particularly limited, but from the viewpoint of stable operation of the baking equipment, It is preferably 10% by weight or more. The upper limit of the content of the volatile component is not particularly limited, but is preferably 95% by weight or less, more preferably 80% by weight or less, and more preferably 50% by weight or less from the viewpoint of suppressing the generation of tar content in the baking equipment. Further preferred. The volatile component is calculated from the ignition residue after charging the sample in an inert gas and the amount charged. The strong heat is obtained by putting approximately 1 g of volatile organic substances (this exact weight is W ₀ (g)) into a crucible and flowing the crucible at 10 ° C./min in an electric furnace at 20 ° C./min while flowing 20 liters of nitrogen per minute. The temperature is raised to 0 ° C. and then ignited at 800 ° C. for 1 hour. The residue at this time is regarded as an ignition residue, the weight thereof is defined as W (g), and the volatile component P (%) is calculated from the following formula.

  Examples of volatile organic substances include thermoplastic resins and low molecular organic compounds. Specifically, examples of the thermoplastic resin include polystyrene, polyethylene, polypropylene, poly (meth) acrylic acid, poly (meth) acrylic acid ester, and the like. In this specification, (meth) acryl is a general term for methacryl and methacryl. Examples of the low molecular organic compound include toluene, xylene, mesitylene, styrene, naphthalene, phenanthrene, anthracene, and pyrene. Since those which do not oxidize and activate the surface of the carbon precursor when volatilized at the firing temperature and thermally decomposed are preferable, polystyrene, polyethylene and polypropylene are preferable as the thermoplastic resin. The low molecular weight organic compound preferably has low volatility at room temperature from the viewpoint of safety, and naphthalene, phenanthrene, anthracene, pyrene and the like are preferable.

  In one embodiment of the present invention, examples of the thermoplastic resin include olefin-based resins, styrene-based resins, and (meth) acrylic acid-based resins. Examples of the olefin resin include polyethylene, polypropylene, a random copolymer of ethylene and propylene, and a block copolymer of ethylene and propylene. Examples of the styrene resin include polystyrene, poly (α-methylstyrene), a copolymer of styrene and an alkyl (meth) acrylate (the alkyl group has 1 to 12, preferably 1 to 6 carbon atoms). Can do. Examples of the (meth) acrylic resin include polyacrylic acid, polymethacrylic acid, (meth) acrylic acid alkyl ester polymer (the alkyl group has 1 to 12 carbon atoms, preferably 1 to 6 carbon atoms), and the like. it can.

  In one embodiment of the present invention, for example, a hydrocarbon compound having 1 to 20 carbon atoms can be used as the low molecular organic compound. Carbon number of a hydrocarbon compound becomes like this. Preferably it is 2-18, More preferably, it is 3-16. The hydrocarbon compound may be a saturated hydrocarbon compound or an unsaturated hydrocarbon compound, and may be a chain hydrocarbon compound or a cyclic hydrocarbon compound. In the case of an unsaturated hydrocarbon compound, the unsaturated bond may be a double bond or a triple bond, and the number of unsaturated bonds contained in one molecule is not particularly limited. For example, the chain hydrocarbon compound is an aliphatic hydrocarbon compound, and can include a linear or branched alkane, alkene, or alkyne. Examples of the cyclic hydrocarbon compound include alicyclic hydrocarbon compounds (for example, cycloalkane, cycloalkene, cycloalkyne) and aromatic hydrocarbon compounds. Specifically, examples of the aliphatic hydrocarbon compound include methane, ethane, propane, butane, pentane, hexane, octane, nonane, decane, ethylene, propylene, butene, pentene, hexene, and acetylene. Examples of the alicyclic hydrocarbon compound include cyclopentane, cyclohexane, cycloheptane, cyclooctane, cyclononane, cyclopropane, cyclopentene, cyclohexene, cycloheptene, cyclooctene, decalin, norbornene, methylcyclohexane, and norbornadiene. Further, aromatic hydrocarbon compounds include benzene, toluene, xylene, mesitylene, cumene, butylbenzene, styrene, α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, vinylxylene, p- Examples thereof include monocyclic aromatic compounds such as tert-butylstyrene and ethylstyrene, and tricyclic to 6-ring condensed polycyclic aromatic compounds such as naphthalene, phenanthrene, anthracene, and pyrene, preferably condensed polycyclic aromatic compounds. A compound, more preferably naphthalene, phenanthrene, anthracene or pyrene. Here, the hydrocarbon compound may have an arbitrary substituent. The substituent is not particularly limited, and for example, an alkyl group having 1 to 4 carbon atoms (preferably an alkyl group having 1 to 2 carbon atoms) or an alkenyl group having 2 to 4 carbon atoms (preferably alkenyl having 2 carbon atoms). Group) and a cycloalkyl group having 3 to 8 carbon atoms (preferably a cycloalkyl group having 3 to 6 carbon atoms).

  The volatile organic material is preferably solid at room temperature, for example, a thermoplastic resin that is solid at room temperature such as polystyrene, polyethylene, or polypropylene, or a low-molecular organic compound that is solid at room temperature such as naphthalene, phenanthrene, anthracene, or pyrene. More preferred. Since those which volatilize and do not oxidize the surface of the plant-derived char carbon precursor when pyrolyzed at the firing temperature are preferred, the thermoplastic resin is preferably an olefin resin and a styrene resin, polystyrene, More preferred are polyethylene and polypropylene. The low molecular weight organic compound is preferably a hydrocarbon compound having 1 to 20 carbon atoms, more preferably a condensed polycyclic aromatic compound, and more preferably naphthalene, phenanthrene, and anthracene, because it is preferable from the viewpoint of safety that the volatility is low at room temperature. Or pyrene is more preferable. Furthermore, from the viewpoint of easy mixing with the carbon precursor, a thermoplastic resin is preferable, an olefin resin and a styrene resin are more preferable, polystyrene, polyethylene, and polypropylene are further preferable, and polystyrene and polyethylene are particularly preferable.

The residual carbon ratio is measured by quantifying the carbon content of the ignition residue after the sample is ignited in an inert gas. Intense heat means that about 1 g of volatile organic substances (this exact weight is W ₁ (g)) is put in a crucible and 20 liters of nitrogen is allowed to flow for 1 minute while the crucible is placed in an electric furnace at 10 ° C./min. The temperature is raised from room temperature to 800 ° C. at a rate of temperature rise of 1, and then ignited at 800 ° C. for 1 hour. The residue at this time is regarded as an ignition residue, and its weight is defined as W ₂ (g).

Next, the ignition residue is subjected to elemental analysis in accordance with the method defined in JIS M8819, and the carbon weight ratio P ₁ (%) is measured. The remaining coal rate P ₂ (%) is calculated by the following equation.

  Although the mixture baked in this embodiment is not specifically limited, Preferably it is a mixture containing a carbon precursor and a volatile organic substance in the weight ratio of 97: 3 to 40:60. The mixing amount of the carbon precursor and the volatile organic substance is more preferably 95: 5 to 60:40, and still more preferably 93: 7 to 80:20. For example, when the volatile organic substance is 3 parts by weight or more, the specific surface area can be sufficiently reduced. On the other hand, if there are too many volatile organic substances, the effect of reducing the specific surface area is saturated, and the volatile organic substances may be consumed in vain, which is not preferable.

  Mixing of the carbon precursor and the volatile organic substance that is liquid or solid at room temperature may be performed at any stage before or after the grinding process.

  When mixing before the pulverization step, the carbon precursor and the liquid or solid volatile organic substance at room temperature are weighed and simultaneously supplied to the pulverizer to simultaneously perform pulverization and mixing. In addition, when using volatile organic substances that are gases at room temperature, non-oxidizing gas containing gaseous volatile organic substances is circulated in a heat treatment apparatus containing char-carbon precursors derived from plants and thermally decomposed, resulting in the substance It is possible to use a method of mixing with the char carbon precursor.

  In the case of mixing after the pulverization step, a known mixing method can be used as long as the mixing method is a method in which both are uniformly mixed. When the volatile organic substance is solid at room temperature, it is preferably mixed in the form of particles, but the shape and particle diameter of the particles are not particularly limited. From the viewpoint of uniformly dispersing the volatile organic substance in the pulverized carbon precursor, the average particle diameter of the volatile organic substance is preferably 0.1 to 2000 μm, more preferably 1 to 1000 μm, and still more preferably 2 to 600 μm. .

  The mixture mentioned above may contain other components other than the carbon precursor and the volatile organic substance. For example, natural graphite, artificial graphite, metal-based material, alloy-based material, or oxide-based material can be included. The content of other components is not particularly limited, but is preferably 50 parts by weight or less, more preferably 30 parts by weight with respect to 100 parts by weight of the mixture of the carbon precursor and the volatile organic material. Or less, more preferably 20 parts by weight or less, and most preferably 10 parts by weight or less.

  The baking process in the manufacturing method of this embodiment bakes the mixture of a carbon precursor and volatile organic substance at 800-1400 degreeC.

The firing process
(A) The pulverized mixture may be baked at 800 to 1400 ° C. to perform a main baking,
(B) The pulverized mixture may be preliminarily calcined at 350 ° C. or higher and lower than 800 ° C., and then subjected to main calcining at 800 to 1400 ° C.

  When the firing step (a) is performed, it is considered that the carbon precursor is covered with the tar component and the hydrocarbon-based gas in the main firing step. In the case of carrying out the firing step (b), it is considered that the carbon precursor is coated with the tar component and hydrocarbon gas in the preliminary firing step.

  Hereinafter, as an embodiment of the present invention, an example of the pre-baking and main baking procedures will be described, but the present invention is not limited thereto.

(Preliminary firing)
The preliminary baking step in the present embodiment can be performed by baking the pulverized mixture at 350 ° C. or higher and lower than 800 ° C., for example. Volatile components (for example, CO ₂ , CO, CH ₄ , H _2, etc.) and tar components can be removed by the preliminary firing step. Generation | occurrence | production of the volatile matter and tar part in the main baking process implemented after a preliminary baking process can be reduced, and the burden of a baking machine can be reduced.

  The pre-baking step is preferably performed at 350 ° C. or higher, more preferably 400 ° C. or higher. The pre-baking step can be performed according to a normal pre-baking procedure. Specifically, the pre-baking can be performed in an inert gas atmosphere. Examples of the inert gas include nitrogen and argon. Further, the pre-baking may be performed under reduced pressure, for example, 10 kPa or less. The pre-baking time is not particularly limited, but can be carried out in the range of 0.5 to 10 hours, for example, and more preferably 1 to 5 hours.

(Main firing)
The main baking step can be performed according to a normal main baking procedure. By performing the main firing, a carbonaceous material for a non-aqueous electrolyte secondary battery can be obtained.

  The specific temperature of the main firing step is 800 to 1400 ° C, preferably 1000 to 1350 ° C, and more preferably 1100 to 1300 ° C. The main firing is performed in an inert gas atmosphere. Examples of the inert gas include nitrogen, argon, and the like, and the main calcination can be performed in an inert gas containing a halogen gas. Moreover, this baking process can also be performed under reduced pressure, for example, it is also possible to implement at 10 kPa or less. Although the time which implements this baking process is not specifically limited, For example, it can carry out in 0.05 to 10 hours, 0.05 to 8 hours are preferable and 0.05 to 6 hours are more preferable.

  According to the production method of the present invention, a carbonaceous material having a good resistance against oxidative deterioration as well as a good discharge capacity can be obtained. The carbonaceous material produced by the production method of the present invention has good resistance to oxidative degradation, suppresses an increase in irreversible capacity due to inactivation of lithium ions, and maintains high charge / discharge efficiency. Can do.

The specific surface area of the carbonaceous material of the present invention ^is preferably 1m ² / g~10m 2 / g, more preferably 1.2m ² /g~9.5m ² / g, more preferably 1.4 m ² / G to 9.0 m ² / g. When the specific surface area is too small, the amount of lithium ions adsorbed on the carbonaceous material is decreased, and the charge capacity of the nonaqueous electrolyte secondary battery may be decreased. When the specific surface area is too high, lithium ions react on the surface of the carbonaceous material and are consumed, so that the utilization efficiency of lithium ions is lowered.
In order to make a specific surface area into the said range, the method of adjusting the baking temperature and baking time of the carbonaceous precursor which gives a carbonaceous material can be used, for example. That is, if the firing temperature is increased or the firing time is increased, the specific surface area tends to decrease. Therefore, the firing temperature and the firing time may be adjusted so that the specific surface area in the above range can be obtained. Moreover, you may use the method of mixing and baking with a volatile organic compound. As described above, the carbonaceous film obtained by heat treatment of the volatile organic compound is formed on the surface of the carbon precursor by mixing and firing the carbonaceous precursor and the volatile organic compound. it is conceivable that. And it is thought by this carbonaceous film that the specific surface area of the carbonaceous material obtained from the carbon precursor reduces. Therefore, it can adjust to said range of the specific surface area of a carbonaceous material by adjusting the quantity of the volatile organic compound to mix.

The carbonaceous material of the present invention preferably has an average interplanar spacing d ₀₀₂ of (002) plane calculated from the wide-angle X-ray diffraction method using the Bragg equation in the range of 0.38 nm to 0.40 nm. More preferably, it is in the range of not less than 0.381 nm and not more than 0.389 nm. When the average spacing d ₀₀₂ of (002) plane is too small, there is the resistance when the lithium ions are inserted into the carbon material increases, there is the resistance increases at the time of output, the lithium ion Input / output characteristics as a battery may deteriorate. In addition, since the carbonaceous material repeatedly expands and contracts, the stability as the battery material may be impaired. If the average interplanar spacing _d002 is too large, the diffusion resistance of lithium ions will be small, but the volume of the carbonaceous material will be large, and the effective capacity per volume may be small. In order to adjust the average spacing to the above range, for example, the firing temperature of the carbonaceous precursor that gives the carbonaceous material may be in the range of 800 to 1400 ° C. Alternatively, a method of mixing with a pyrolyzable resin such as polystyrene and baking can be used.

Further, as another aspect of the carbonaceous material obtained by the production method of the present invention, the average spacing of (002) planes by X-ray diffraction method is 0.36 to 0.42 nm, and the BET specific surface area is 1 to 20 m. ^The nitrogen element content is 0.5% by weight or less, and the oxygen element content is 0.25% by weight or less. The specific surface area of the carbonaceous material of this ^{embodiment, 1m 2 / g~20m 2 / g} , preferably 1.2m ² / g~15m ² / g, more preferably 1.5m ² / g~10m ² / g is there. In order to make the specific surface area within the above range, a method of adjusting the firing temperature and firing time of the carbonaceous precursor that gives the carbonaceous material can be used as described above. Further, the average spacing is 0.36 nm to 0.42 nm, preferably 0.38 nm to 0.40 nm, and more preferably 0.382 nm to 0.396 nm. In order to make the average interplanar spacing within the above range, the firing temperature of the carbonaceous precursor that gives the carbonaceous material may be set in the range of 800 to 1400 ° C. as described above.

The content of nitrogen element contained in the carbonaceous material of the present invention is preferably as low as possible. However, it is usually 0.5% by weight or less, preferably 0.48% by weight or less, more preferably 0, from the analytical value obtained by elemental analysis. .45% by weight or less. More preferably, the carbonaceous material contains substantially no nitrogen element. Here, “substantially not contained” means that it is 10 ⁻⁶ wt% or less which is a detection limit of an elemental analysis method (inert gas melting-heat conduction method) described later. If the nitrogen element content is too high, lithium ions and nitrogen react to consume lithium ions, which not only reduces the utilization efficiency of lithium ions, but may also react with oxygen in the air during storage .
The method for adjusting the nitrogen element content to the above range is not limited at all. For example, a gas phase is a method including a step of heat-treating plant-derived char at 500 ° C. to 940 ° C. in an inert gas atmosphere containing a halogen compound. The nitrogen element content can be adjusted to the above range by deashing or by mixing and baking the plant-derived char with the volatile organic substance.

The amount of oxygen element contained in the carbonaceous material obtained in the present embodiment is preferably as low as possible, but is usually 0.25% by weight or less, preferably 0.24% by weight or less, based on the analytical value obtained by elemental analysis. . More preferably, the carbonaceous material contains substantially no oxygen element. Here, “substantially not contained” means that it is 10 ⁻⁶ wt% or less which is a detection limit of an elemental analysis method (inert gas melting-heat conduction method) described later. If the oxygen element content is too high, lithium ions react with oxygen to consume lithium ions, thereby reducing the utilization efficiency of lithium ions. Furthermore, it not only increases the probability of attracting oxygen and moisture in the air and reacts with the carbonaceous material, but also reduces the efficiency of using lithium ions, such as not easily desorbing when water is adsorbed. .
The method for adjusting the oxygen element content to the above range is not limited at all. For example, the gas phase is a method including a step of heat-treating plant-derived char at 500 ° C. to 940 ° C. in an inert gas atmosphere containing a halogen compound. By decalcifying or mixing and baking plant-derived char with volatile organic substances, the oxygen element content can be adjusted to the above range.

From the viewpoint of increasing the capacity per weight of the battery, the carbonaceous material of the present invention preferably has a true density ρ _Bt by the butanol method of 1.40 to 1.70 g / cm ³ , and 1.42 to 1. More preferably, it is 65 / cm ³ , and still more preferably 1.44 to 1.60 / cm ³ . The plant-derived char carbon precursor having such a true density can be produced, for example, by firing a plant material at 800-1400 ° C. Here, the details of the measurement of the true density ρ _Bt are as described in the examples, and can be measured by the butanol method according to the method defined in JIS R 7212.

  The carbonaceous material of the present invention preferably has an Lc (carbon hexagonal area layer direction) of 3 nm or less, particularly from the viewpoint of repetitive characteristics in lithium doping and dedoping required for automotive applications and the like. Lc is more preferably 0.5 to 2 nm. When Lc exceeds 3 nm, carbon hexagonal network surfaces are stacked in multiple layers, and volume expansion and contraction accompanying lithium doping and dedoping may increase. Therefore, the carbon structure is destroyed by volume expansion and contraction, lithium doping / dedoping is interrupted, and the repeated characteristics may be deteriorated. Here, the details of the measurement of Lc are as described in Examples, and can be obtained by the X-ray diffraction method using Scherrer's equation.

The average particle diameter (Dv ₅₀ ) of the carbonaceous material of the present invention is preferably 3 to 30 μm. If the average particle size is too small, fine powder increases and the specific surface area of the carbonaceous material increases. As a result, the reactivity between the carbonaceous material and the electrolytic solution increases, the irreversible capacity increases, and the rate at which the positive electrode capacity is wasted may increase. Here, the irreversible capacity is a capacity that does not discharge among the capacity charged in the non-electrolyte secondary battery. When a negative electrode is produced using a carbonaceous material having an average particle size that is too small, voids formed between the carbonaceous materials are reduced, and movement of lithium in the electrolytic solution is restricted, which is not preferable. The average particle diameter of the carbonaceous material is more preferably 4 μm or more, and particularly preferably 5 μm or more. When the average particle size is 30 μm or less, the lithium free diffusion process in the particles is small, and rapid charge / discharge is possible, which is preferable. Further, in the lithium ion secondary battery, it is important to increase the electrode area for improving the input / output characteristics. For this reason, it is necessary to reduce the coating thickness of the active material on the current collector plate during electrode preparation. In order to reduce the coating thickness, it is necessary to reduce the particle diameter of the active material. From such a viewpoint, the upper limit of the average particle diameter is preferably 30 μm or less, more preferably 19 μm or less, still more preferably 17 μm or less, still more preferably 16 μm or less, and most preferably 15 μm or less.

  The moisture absorption of the carbonaceous material of the present invention is preferably 15,000 ppm or less, more preferably 13,000 ppm or less, and still more preferably 10,000 ppm or less. The smaller the amount of moisture absorption, the more the moisture adsorbed on the carbonaceous material decreases, and the more lithium ions adsorbed on the carbonaceous material increase. Further, it is preferable that the amount of moisture absorption is small because the self-discharge due to the reaction between the adsorbed moisture and the nitrogen atom of the carbonaceous material and the reaction between the adsorbed moisture and lithium ion can be reduced. The moisture absorption amount of the carbonaceous material can be reduced by reducing the amount of nitrogen atoms and oxygen atoms contained in the carbonaceous material, for example. The amount of moisture absorption of the carbonaceous material can be measured using, for example, a Karl Fischer.

(Negative electrode for non-aqueous electrolyte secondary battery)
The negative electrode for nonaqueous electrolyte secondary batteries of the present invention contains the carbonaceous material for nonaqueous electrolyte secondary batteries of the present invention.

  Below, the manufacturing method of the negative electrode for nonaqueous electrolyte secondary batteries of this invention is described concretely. The negative electrode of the present invention is obtained by adding a binder (binder) to the carbonaceous material of the present invention, adding an appropriate amount of an appropriate solvent, kneading to form an electrode mixture, and then applying it to a current collector plate made of a metal plate or the like -It can be manufactured by pressure molding after drying.

  By using the carbonaceous material of the present invention, an electrode having high conductivity can be produced without adding a conductive additive. For the purpose of imparting higher conductivity, a conductive aid can be added as necessary when preparing the electrode mixture. As the conductive assistant, conductive carbon black, vapor grown carbon fiber (VGCF), nanotube, or the like can be used. The amount of conductive auxiliary agent added varies depending on the type of conductive auxiliary agent used, but if the amount added is too small, the expected conductivity may not be obtained, and if too large, the dispersion in the electrode mixture will be poor. May be. From such a point of view, a preferable ratio of the conductive auxiliary agent to be added is 0.5 to 10% by weight (where the amount of the active material (carbonaceous material) + the binder amount + the conductive auxiliary agent amount = 100% by weight). More preferably 0.5 to 7% by weight, particularly preferably 0.5 to 5% by weight. The binder is not particularly limited as long as it does not react with an electrolytic solution such as PVDF (polyvinylidene fluoride), polytetrafluoroethylene, and a mixture of SBR (styrene-butadiene rubber) and CMC (carboxymethylcellulose). Among them, PVDF is preferable because PVDF attached to the surface of the active material hardly inhibits lithium ion migration and obtains favorable input / output characteristics. In order to dissolve PVDF and form a slurry, a polar solvent such as N-methylpyrrolidone (NMP) is preferably used, but an aqueous emulsion such as SBR or CMC can also be dissolved in water. When the amount of the binder added is too large, the resistance of the obtained electrode increases, so that the internal resistance of the battery increases and the battery characteristics may be deteriorated. Moreover, when there is too little addition amount of a binder, the coupling | bonding between the particles of negative electrode material and a collector may become inadequate. Although the preferable addition amount of a binder changes also with kinds of binder to be used, for example, in the case of a PVDF-type binder, it is preferably 3 to 13% by weight, and more preferably 3 to 10% by weight. On the other hand, in a binder using water as a solvent, a mixture of a plurality of binders such as a mixture of SBR and CMC is often used, and the total amount of all binders used is preferably 0.5 to 5% by weight. Preferably it is 1-4 weight%.

  The electrode active material layer is basically formed on both sides of the current collector plate, but may be formed on one side as necessary. The thicker the electrode active material layer, the fewer current collector plates, separators, and the like, which is preferable for increasing the capacity. However, since the larger the electrode area facing the counter electrode is, the more advantageous the input / output characteristics are. Therefore, if the electrode active material layer is too thick, the input / output characteristics may deteriorate. A preferable thickness of the active material layer (per one side) is 10 to 80 μm, more preferably 20 to 75 μm, and particularly preferably 20 to 60 μm from the viewpoint of output during battery discharge.

(Non-aqueous electrolyte secondary battery)
The nonaqueous electrolyte secondary battery of the present invention includes the negative electrode for a nonaqueous electrolyte secondary battery of the present invention. The nonaqueous electrolyte secondary battery using the negative electrode for a nonaqueous electrolyte secondary battery using the carbonaceous material of the present invention exhibits excellent output characteristics and excellent cycle characteristics.

  When the negative electrode for a non-aqueous electrolyte secondary battery is formed using the carbonaceous material of the present invention, other materials constituting the battery, such as a positive electrode material, a separator, and an electrolytic solution, are not particularly limited. Various materials conventionally used or proposed as a solvent secondary battery can be used.

For example, as the positive electrode material, a layered oxide system (represented as LiMO ₂ , where M is a metal: for example, LiCoO ₂ , LiNiO ₂ , LiMnO ₂ , or LiNi _x Co _y Mo _z O ₂ (where x, y , Z represents a composition ratio)), olivine system (represented by LiMPO ₄ , M is a metal: for example LiFePO _4, etc.), spinel system (represented by LiM ₂ O ₄ , M is a metal: for example LiMn ₂ O _4, etc. ) Is preferable, and these chalcogen compounds may be mixed as necessary. These positive electrode materials are molded together with an appropriate binder and a carbon material for imparting conductivity to the electrode, and a positive electrode is formed by forming a layer on the conductive current collector.

The nonaqueous solvent electrolyte used in combination with these positive electrode and negative electrode is generally formed by dissolving an electrolyte in a nonaqueous solvent. Examples of the non-aqueous solvent include propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, dimethoxyethane, diethoxyethane, γ-butyllactone, tetrahydrofuran, 2-methyltetrahydrofuran, sulfolane, and 1,3-dioxolane. Can be used singly or in combination of two or more. As the electrolyte, LiClO ₄ , LiPF ₆ , LiBF ₄ , LiCF ₃ SO ₃ , LiAsF ₆ , LiCl, LiBr, LiB (C ₆ H ₅ ) ₄ , or LiN (SO ₃ CF ₃ ) ₂ is used.

  In nonaqueous electrolyte secondary batteries, the positive electrode and the negative electrode formed as described above are generally immersed in an electrolytic solution so that they face each other through a liquid-permeable separator made of a nonwoven fabric, other porous materials, or the like as necessary. Is formed. As the separator, a non-woven fabric usually used for a secondary battery or a permeable separator made of another porous material can be used. Alternatively, a solid electrolyte made of a polymer gel impregnated with an electrolytic solution can be used instead of or together with the separator.

  The carbonaceous material for a non-aqueous electrolyte secondary battery of the present invention is suitable as a carbonaceous material for a battery (typically a non-aqueous electrolyte secondary battery for driving a vehicle) mounted on a vehicle such as an automobile. In the present invention, the vehicle can be a target such as a vehicle that is usually used as an electric vehicle, a hybrid vehicle with a fuel cell or an internal combustion engine, and the like, but at least a power supply device including the battery. And an electric drive mechanism that is driven by power supply from the power supply device, and a control device that controls the electric drive mechanism. The vehicle may further include a power generation brake and a regenerative brake, and may include a mechanism that converts energy generated by braking into electricity and charges the nonaqueous electrolyte secondary battery.

  EXAMPLES Hereinafter, the present invention will be specifically described by way of examples, but these do not limit the scope of the present invention. In addition, although the measuring method of the physical-property value of the carbonaceous material for nonaqueous electrolyte secondary batteries is described below, the physical-property value described in this specification including an Example is the value calculated | required by the following method. Is based.

(Specific surface area measurement by nitrogen adsorption method)
An approximate expression derived from the BET expression is described below.

Using the above approximate equation, _vm was determined by a three-point method by nitrogen adsorption at liquid nitrogen temperature, and the specific surface area of the sample was calculated by the following equation.

In this case, v _m adsorption amount necessary to form a monomolecular layer on the surface of the sample ^(cm 3 / g), v adsorption amount is measured _{^{(cm 3 / g), p}} 0 is saturation vapor pressure, p is Absolute pressure, c is a constant (reflecting heat of adsorption), N is Avogadro's number 6.022 × 10 ²³ , and a (nm ² ) is an area occupied by the adsorbate molecule on the sample surface (molecular occupation cross-sectional area).

  Specifically, the amount of nitrogen adsorbed on the carbon material at the liquid nitrogen temperature was measured as follows using “BELL Sorb Mini” manufactured by BELL JAPAN. A carbon material pulverized to a particle diameter of about 5 to 50 μm is filled in a sample tube, and the sample tube is cooled to −196 ° C., and once depressurized, nitrogen (purity 99.999) is added to the carbon material at a desired relative pressure. %) Is adsorbed. The amount of nitrogen adsorbed on the sample when the equilibrium pressure was reached at each desired relative pressure was defined as the amount of adsorbed gas v.

(Measurement of average surface distance _d002 by X-ray diffraction method)
Using “MiniFlexII manufactured by Rigaku Corporation”, an X-ray diffraction pattern was obtained using a CuKα ray filled with a carbonaceous material powder in a sample holder and monochromated by a Ni filter as a radiation source. The peak position of the diffraction pattern is obtained by the barycentric method (a method of obtaining the barycentric position of the diffraction line and obtaining the peak position by the corresponding 2θ value), and using the diffraction peak on the (111) plane of the high-purity silicon powder for standard materials. Corrected. The wavelength of the CuKα ray was 0.15418 nm, and d ₀₀₂ was calculated according to the Bragg formula described below.

(Elemental analysis)
Elemental analysis was performed using an oxygen / nitrogen / hydrogen analyzer EMGA-930 manufactured by HORIBA, Ltd.
The detection method of the apparatus is as follows: oxygen: inert gas melting-non-dispersive infrared absorption method (NDIR), nitrogen: inert gas melting-thermal conductivity method (TCD), hydrogen: inert gas melting-non-dispersing infrared ray It is an absorption method (NDIR), and calibration is carried out with (oxygen / nitrogen) Ni capsules, TiH ₂ (H standard sample), SS-3 (N, O standard sample). 20 mg of the sample whose moisture content was measured was taken in a Ni capsule and measured after degassing for 30 seconds in the elemental analyzer. In the test, three samples were analyzed, and the average value was used as the analysis value.

(Measurement of residual coal rate)
The residual carbon ratio was measured by quantifying the carbon content of the ignition residue after the sample was ignited in an inert gas. The strong heat is obtained by putting about 1 g of volatile organic substances (this exact weight is W ₁ (g)) into the crucible and flowing the crucible in an electric furnace at 10 ° C./min while flowing 20 liters of nitrogen per minute. The temperature was raised from room temperature to 800 ° C. at a rate of temperature rise, and then ignited at 800 ° C. for 1 hour. The residue at this time was regarded as an ignition residue, and its weight was defined as W ₂ (g).
Next, the ignition residue was subjected to elemental analysis in accordance with the method defined in JIS M8819, and the carbon weight ratio P ₁ (%) was measured. The residual coal rate P ₂ (%) was calculated by the following formula.

このとき、ｄは水の３０℃における比重（０．９９４６）である。 (True density by butanol method)
The true density was measured by a butanol method according to a method defined in JIS R 7212. The mass (m ₁ ) of a specific gravity bottle with a side tube having an internal volume of about 40 mL was accurately measured. Next, the sample was put flat on the bottom so as to have a thickness of about 10 mm, and the mass (m ₂ ) was accurately measured. To this, 1-butanol was gently added to a depth of about 20 mm from the bottom. Next, light vibration was applied to the specific gravity bottle, and it was confirmed that large bubbles were not generated. Then, the bottle was placed in a vacuum desiccator and gradually evacuated to 2.0 to 2.7 kPa. Keep at that pressure for 20 minutes or more, and after the generation of bubbles has stopped, take it out, fill it with 1-butanol, plug it and immerse it in a constant temperature water bath (adjusted to 30 ± 0.03 ° C) for 15 minutes or more. The liquid level of 1-butanol was adjusted to the marked line. Next, this was taken out, wiped out well, cooled to room temperature, and then the mass (m ₄ ) was accurately measured. Next, the same specific gravity bottle was filled with only 1-butanol, immersed in a constant temperature water bath in the same manner as described above, and the mass (m ₃ ) was measured after aligning the marked lines. Moreover, distilled water excluding the gas which had been boiled and dissolved immediately before use was taken in a specific gravity bottle, immersed in a constant temperature water bath in the same manner as described above, and the mass (m ₅ ) was measured after aligning the marked lines.
The true density ρ _Bt was calculated by the following formula.

At this time, d is the specific gravity of water at 30 ° C. (0.9946).

(Average particle size)
The average particle size (particle size distribution) of plant-derived char and carbonaceous material was measured, for example, by the following method. The sample was put into an aqueous solution containing 0.3% by mass of a surfactant (“Toriton X100” manufactured by Wako Pure Chemical Industries, Ltd.), treated with an ultrasonic cleaner for 10 minutes or more, and dispersed in the aqueous solution. The particle size distribution was measured using this dispersion. The particle size distribution measurement was performed using a particle size / particle size distribution measuring apparatus (“Microtrack MT3000” manufactured by Nikkiso Co., Ltd.). d50 is the particle diameter at which the cumulative volume is 50%, and this value was used as the average particle diameter.

(Metal content)
The measuring method of potassium element content and iron element content was measured, for example, by the following method. A carbon sample containing a predetermined potassium element and iron element is prepared in advance, and using a fluorescent X-ray analyzer, the relationship between the intensity of potassium Kα ray and the potassium content, and the intensity of iron Kα ray and the iron content A calibration curve for the relationship was created. Subsequently, the intensity | strength of the potassium K alpha ray and iron K alpha ray in a fluorescent X ray analysis was measured about the sample, and potassium content and iron content were calculated | required from the analytical curve created previously. The fluorescent X-ray analysis was performed using LAB CENTER XRF-1700 manufactured by Shimadzu Corporation under the following conditions. Using the upper irradiation system holder, the sample measurement area was within the circumference of 20 mm in diameter. The sample to be measured was placed by placing 0.5 g of the sample to be measured in a polyethylene container having an inner diameter of 25 mm, pressing the back with a plankton net, and covering the measurement surface with a polypropylene film for measurement. The X-ray source was set to 40 kV and 60 mA. For potassium, LiF (200) was used for the spectroscopic crystal and a gas flow proportional coefficient tube was used for the detector, and 2θ was measured in the range of 90 to 140 ° at a scanning speed of 8 ° / min. For iron, LiF (200) was used for the spectroscopic crystal, and a scintillation counter was used for the detector, and 2θ was measured in the range of 56 to 60 ° at a scanning speed of 8 ° / min.

(Moisture absorption)
10 g of carbon material pulverized to a particle size of about 5 to 50 μm is put in a sample tube, pre-dried at 120 ° C. for 2 hours under a reduced pressure of 133 Pa, transferred to a 50 mmφ glass petri dish, and kept at a constant temperature and constant temperature of 25 ° C. and humidity 50%. It was exposed for a predetermined time in a damp bath. 1 g of a sample was taken, heated to 250 ° C. by Karl Fischer (manufactured by Mitsubishi Chemical Analytech Co., Ltd.), and the water content was measured under a nitrogen stream.

(Preparation Example 1)
The coconut shell was crushed and dry-distilled at 500 ° C. to obtain coconut shell char having a particle size of 2.360 to 0.850 mm (containing 98 wt% of particles having a particle size of 2.360 to 0.850 mm). A vapor phase deashing process was performed for 50 minutes at 900 ° C. while supplying nitrogen gas containing 1% by volume of hydrogen chloride gas at a flow rate of 10 L / min to 100 g of this coconut shell char. Thereafter, only the supply of hydrogen chloride gas was stopped, and while supplying nitrogen gas at a flow rate of 10 L / min, vapor phase deoxidation treatment was further performed at 900 ° C. for 30 minutes to obtain a carbon precursor.
The obtained carbon precursor was roughly pulverized to an average particle size of 10 μm using a ball mill, and then pulverized and classified using a compact jet mill (manufactured by Seishin Enterprise Co., Ltd., Kodget System α-mkIII) to obtain an average particle size. A carbon precursor of 9.6 μm was obtained. The specific surface area of the obtained carbon precursor was 210 m ² / g.

(Preparation Example 2)
A carbon precursor was obtained in the same manner as in Preparation Example 1, except that the vapor phase deashing temperature and the vapor phase deoxidation temperature were changed to 870 ° C. The specific surface area of the obtained carbon precursor was 350 m ² / g.

(Preparation Example 3)
A carbon precursor was obtained in the same manner as in Preparation Example 1 except that the vapor phase deashing temperature and the vapor phase deoxidation temperature were changed to 950 ° C. The specific surface area of the obtained carbon precursor was 70 m ² / g.

(Preparation Example 4)
A carbon precursor was obtained in the same manner as in Preparation Example 1, except that the vapor phase deashing temperature and the vapor phase deoxidation temperature were changed to 800 ° C. The specific surface area of the obtained carbon precursor was 520 m ² / g.

Example 1
9.1 g of the carbon precursor prepared in Preparation Example 1 and 0.9 g of polystyrene (manufactured by Sekisui Plastics Co., Ltd., average particle diameter of 400 μm, residual carbon ratio of 1.2%) were mixed. 10 g of this mixture was placed in a graphite sheath (length 100 mm, width 100 mm, height 50 mm), and 1290 ° C. at a heating rate of 60 ° C. per minute under a 5 L / min nitrogen flow rate in a high-speed heating furnace manufactured by Motoyama Co., Ltd. After being heated up to 11 minutes, it was kept for 11 minutes and naturally cooled. After confirming that the furnace temperature had dropped to 200 ° C. or less, the carbonaceous material was taken out of the furnace. The recovered carbonaceous material was 8.1 g, and the recovery rate with respect to the carbon precursor was 89%. Table 1 shows the physical properties of the obtained carbonaceous material.

(Example 2)
A carbonaceous material was obtained in the same manner as in Example 1 except that the carbon precursor prepared in Preparation Example 2 was used. The recovered amount of the carbonaceous material was 8.1 g, and the recovery rate with respect to the carbon precursor was 89%. Table 1 shows the physical properties of the obtained carbonaceous material.

(Example 3)
A carbonaceous material was obtained in the same manner as in Example 1 except that the firing temperature was changed to 1270 ° C. The recovered amount of the carbonaceous material was 8.1 g, and the recovery rate with respect to the carbon precursor was 89%. Table 1 shows the physical properties of the obtained carbonaceous material.

Example 4
A carbonaceous material was obtained in the same manner as in Example 2 except that the firing temperature was changed to 1270 ° C. The recovered amount of the carbonaceous material was 8.1 g, and the recovery rate with respect to the carbon precursor was 89%. Table 1 shows the physical properties of the obtained carbonaceous material.

(Example 5)
A carbonaceous material was obtained in the same manner as in Example 1 except that the holding time at 1290 ° C. was changed to 23 minutes. The recovered amount of the carbonaceous material was 8.1 g, and the recovery rate with respect to the carbon precursor was 89%. Table 1 shows the physical properties of the obtained carbonaceous material.

(Example 6)
A carbonaceous material was obtained in the same manner as in Example 2 except that the holding time at 1290 ° C. was changed to 23 minutes. The recovered amount of the carbonaceous material was 8.1 g, and the recovery rate with respect to the carbon precursor was 89%. Table 1 shows the physical properties of the obtained carbonaceous material.

(Example 7)
A carbonaceous material was obtained in the same manner as in Example 2 except that the firing temperature was 1250 ° C. The recovered amount was 8.1 g and the recovery rate was 89%. Table 1 shows the physical properties of the obtained carbonaceous material.

(Example 8)
A carbonaceous material was obtained in the same manner as in Example 2, except that the plant-derived char carbon precursor was 9.6 g and the polystyrene was 0.4 g. The recovered amount was 8.5 g, and the recovery rate was 89%. Table 1 shows the physical properties of the obtained carbonaceous material.

Example 9
A carbonaceous material was obtained in the same manner as in Example 2 except that 0.9 g of polyethylene (manufactured by Sumitomo Seika Co., Ltd., average particle size 250 μm, residual carbon ratio 1.9%) was used instead of polystyrene. The recovered amount was 9.0 g, and the recovery rate was 88%. Table 1 shows the physical properties of the obtained carbonaceous material.

(Comparative Example 1)
9.1 g of the carbon precursor prepared in Preparation Example 3 and 0.9 g of polystyrene (manufactured by Sekisui Plastics Co., Ltd., average particle diameter of 400 μm, residual carbon ratio of 1.2%) were mixed. 10 g of this mixture was placed in a graphite sheath (length 100 mm, width 100 mm, height 50 mm), and 1290 ° C. at a heating rate of 60 ° C. per minute under a 5 L / min nitrogen flow rate in a high-speed heating furnace manufactured by Motoyama Co., Ltd. The temperature was raised to 1, then maintained for 11 minutes, and then naturally cooled. After confirming that the furnace temperature had dropped to 200 ° C. or less, the carbonaceous material was taken out of the furnace. The recovered carbonaceous material was 8.1 g, and the recovery rate with respect to the carbon precursor was 89%. Table 1 shows the physical properties of the obtained carbonaceous material.

(Comparative Example 2)
A carbonaceous material was obtained in the same manner as in Comparative Example 1 except that the carbon precursor prepared in Preparation Example 4 was used. The recovered amount of the carbonaceous material was 8.1 g, and the recovery rate with respect to the carbon precursor was 89%. Table 1 shows the physical properties of the obtained carbonaceous material.

(Comparative Example 3)
A carbonaceous material was obtained in the same manner as in Example 2 except that only the plant-derived char carbon precursor was used and polystyrene was not mixed. Table 1 shows the physical properties of the obtained carbonaceous material.

(Production method of electrode)
Using the carbonaceous materials obtained in Examples 1 to 9 and Comparative Examples 1 to 3, negative electrodes were prepared according to the following procedure.
92 parts by mass of the prepared carbonaceous material, 2 parts by mass of acetylene black, 6 parts by mass of PVDF (polyvinylidene fluoride) and 90 parts by mass of NMP (N-methylpyrrolidone) were mixed to obtain a slurry. The obtained slurry was applied to a copper foil having a thickness of 14 μm, dried and pressed to obtain an electrode having a thickness of 60 μm. The density of the obtained electrode was 0.9 to 1.1 g / cm ³ .

(Battery initial capacity and charge / discharge efficiency)
The electrode produced above was used as a working electrode, and metallic lithium was used as a counter electrode and a reference electrode. As a solvent, ethylene carbonate and methyl ethyl carbonate were mixed and used at a volume ratio of 3: 7. In this solvent, 1 mol / L of LiPF ₆ was dissolved and used as an electrolyte. A glass fiber nonwoven fabric was used for the separator. A coin cell was produced in a glove box under an argon atmosphere.
About the lithium secondary battery of the said structure, the charge / discharge test was done using the charge / discharge test apparatus (the Toyo System Co., Ltd. make, "TOSCAT"). Lithium was doped at a rate of 70 mA / g with respect to the mass of the active material, and was doped until 1 mV with respect to the lithium potential. Further, a constant voltage of 1 mV with respect to the lithium potential was applied for 8 hours to complete the doping. The capacity (mAh / g) at this time was defined as the charge capacity. Next, dedoping was performed at a rate of 70 mA / g with respect to the weight of the active material until 2.5 V with respect to the lithium potential, and the capacity discharged at this time was defined as the discharge capacity. The percentage of discharge capacity / charge capacity was defined as charge / discharge efficiency (initial charge / discharge efficiency), which was used as an index of utilization efficiency of lithium ions in the battery.
Further, after 7 days, the same battery performance was measured again, and the discharge capacity, charge capacity, and charge / discharge efficiency were measured. The value of the charge / discharge efficiency after 7 days relative to the initial charge / discharge efficiency value was defined as the efficiency maintenance rate (%), which was used as an index of the resistance against the oxidative deterioration of the carbonaceous material. The battery performance after 7 days is a value obtained by measuring the same battery performance as that before storage for 7 days after the produced electrode was stored for 7 days at room temperature and in air.
The obtained battery performance is shown in Table 2.

  When the carbonaceous materials obtained in Examples 1 to 9 were used, the charge capacity and the discharge capacity were equivalent to those of the carbonaceous materials obtained in Comparative Examples 1 to 3. This value was satisfactory. Furthermore, when the carbonaceous materials obtained in Examples 1 to 9 were used, the charge / discharge efficiency was good, and the efficiency maintenance rate after 7 days was also good. Moreover, the moisture absorption amount of the carbonaceous material obtained in Examples 1-9 could be reduced more than the carbonaceous material of Comparative Examples 1-3.

  The non-aqueous electrolyte secondary battery using the carbonaceous material of the present invention has a good resistance to oxidative degradation as well as a good charge / discharge capacity. The nonaqueous electrolyte secondary battery using the carbonaceous material for nonaqueous electrolyte secondary batteries of the present invention as a negative electrode has a high doping capacity (charging capacity), a dedoping capacity (discharging capacity), and a low undoping capacity. (Irreversible capacity) and excellent charge / discharge efficiency. Therefore, it can be used particularly for in-vehicle applications such as hybrid vehicles (HEV) and electric vehicles (EV) that require a long life.

Claims (18)

A step of firing a mixture of a carbon precursor having a specific surface area of 100 to 500 m ² / g and a volatile organic substance in an inert gas atmosphere at 800 to 1400 ° C. to obtain a carbonaceous material;
Comprising
A method for producing a carbonaceous material for a non-aqueous electrolyte secondary battery.   The method for producing a carbonaceous material for a nonaqueous electrolyte secondary battery according to claim 1, wherein the carbon precursor is derived from a plant.   The method for producing a carbonaceous material for a non-aqueous electrolyte secondary battery according to claim 1 or 2, wherein the volatile organic substance is in a solid state at room temperature and has a residual carbon ratio of less than 5% by weight. Is calculated using the Bragg equation by wide angle X-ray diffraction method, the average spacing _{d 002} of (002) plane of the carbonaceous material for the nonaqueous electrolyte battery is in the range of 0.36～0.42Nm, nitrogen adsorption The specific surface area of the carbonaceous material for a nonaqueous electrolyte battery determined by the BET three-point method is in the range of 1 to ²⁰ m ² / g, for the nonaqueous electrolyte secondary battery according to any one of claims 1 to 3. A method for producing a carbonaceous material. The nonaqueous electrolyte secondary according to claim 4, wherein an average interplanar spacing d ₀₀₂ of the (002) plane is in the range of 0.38 to 0.40 nm, and the specific surface area is in the range of 1 to 10 m ² / g. A method for producing a carbonaceous material for a battery.   The volatile organic substance is at least one selected from the group consisting of polystyrene, polyethylene, polypropylene, poly (meth) acrylic acid, poly (meth) acrylic acid ester, naphthalene, phenanthrene, anthracene, and pyrene. The manufacturing method of the carbonaceous material for nonaqueous electrolyte secondary batteries of any one of -5. (1) A vapor phase decalcification step including heat-treating plant-derived char at 500 ° C. to 940 ° C. in an inert gas atmosphere containing a halogen compound,
(2) a mixing step of obtaining a mixture comprising char derived from gas phase decalcified and a volatile organic substance having a residual carbon ratio of less than 5% by weight when incinerated at 800 ° C., and (3) The manufacturing method of the carbonaceous material for nonaqueous electrolyte secondary batteries of any one of Claims 1-6 including the process of baking a mixture.   The carbon for nonaqueous electrolyte secondary batteries according to claim 7, wherein a weight ratio of the vapor-decalcified plant-derived char and the volatile organic substance in the mixture is 97: 3 to 40:60. A method for producing quality materials. The firing is
The nonaqueous electrolyte secondary according to claim 7 or 8, which is (a) main baking at 800 to 1600 ° C, or (b) preliminary baking at 350 to less than 800 ° C, and main baking at 800 to 1600 ° C. A method for producing a carbonaceous material for a battery. Is calculated using the Bragg equation by wide angle X-ray diffraction method, the average spacing _{d 002} of (002) plane of the carbonaceous material for the nonaqueous electrolyte battery is in the range of 0.36～0.42Nm, nitrogen adsorption The specific surface area of the carbonaceous material for non-aqueous electrolyte battery determined by the BET three-point method is in the range of 1 to ²⁰ m ² / g, the nitrogen element content is 0.5% by weight or less, and the oxygen element content is 0.25 weight. % Carbonaceous material for non-aqueous electrolyte secondary batteries. 11. The nonaqueous electrolyte secondary according to claim 10, wherein an average interplanar spacing d ₀₀₂ of the (002) plane is in a range of 0.38 to 0.40 nm and the specific surface area is in a range of 1 to 10 m ² / g. Carbonaceous material for batteries. The carbonaceous material for a non-aqueous electrolyte secondary battery is obtained by firing a mixture of a carbon precursor having a specific surface area of 100 to 500 m ² / g and a volatile organic substance in an inert gas atmosphere at 800 to 1400 ° C., The carbonaceous material for nonaqueous electrolyte secondary batteries according to claim 10 or 11.   The carbonaceous material for nonaqueous electrolyte secondary batteries according to claim 12, wherein the carbon precursor is derived from a plant.   The volatile organic substance is at least one selected from the group consisting of polystyrene, polyethylene, polypropylene, poly (meth) acrylic acid, poly (meth) acrylic acid ester, naphthalene, phenanthrene, anthracene, and pyrene. Or the carbonaceous material for nonaqueous electrolyte secondary batteries of 13.   The carbonaceous material for a nonaqueous electrolyte secondary battery according to any one of claims 10 to 14, wherein the potassium element content is 0.1 wt% or less and the iron element content is 0.02 wt% or less. The carbonaceous material for a nonaqueous electrolyte secondary battery according to any one of claims 10 to 15, wherein a true density obtained by a butanol method is 1.40 to 1.70 g / cm ³ .   The negative electrode for nonaqueous electrolyte secondary batteries containing the carbonaceous material for nonaqueous electrolyte secondary batteries of any one of Claims 10-16.   A nonaqueous electrolyte secondary battery comprising the negative electrode for a nonaqueous electrolyte secondary battery according to claim 17.