TW201315006A - Carbon material for lithium ion secondary battery, negative electrode material for lithium ion secondary battery, and lithium ion secondary battery - Google Patents

Abstract

Carbon material for a lithium ion secondary battery of the present invention has an average d-spacing between (002) surfaces of 3.40 to 3.90 Å, which is determined by a wide-angle X-ray diffraction method, and has an amorphous structure with a c-axial crystal size Lc of 8 to 50 Å, and has a graphite structure with a d-spacing between (002) surfaces of 3.25 Å or more and less than 3.40 Å.

Description

Carbon material for lithium ion secondary battery, negative electrode material for lithium ion secondary battery, and lithium ion secondary battery

The present invention relates to a carbon material for a lithium ion secondary battery, a negative electrode material for a lithium ion secondary battery, and a lithium ion secondary battery.

Conventionally, a carbon material is used for the negative electrode of a lithium ion secondary battery. Since it is subjected to a charge and discharge cycle, dendritic lithium is not easily precipitated on the negative electrode using a carbon material, and safety can be ensured.

Among such carbon materials, there are graphite-like highly crystalline materials and amorphous carbon materials called hard carbon. A highly crystalline material such as graphite has an advantage that the irreversible capacity is small and the charge and discharge efficiency is high. Conversely, there is a problem that the charge capacity and the discharge capacity are limited, and it is difficult to increase the capacity. On the other hand, although the amorphous carbon material has a high charge capacity and discharge capacity, it has a problem that the irreversible capacity is large and the charge and discharge efficiency is low. Therefore, materials having both the properties of crystallinity and amorphousness have been reviewed so far. In addition, the charge/discharge capacity refers to the respective capacitances at the time of charging and discharging which are performed for the first time in the battery, and the charge and discharge efficiency refers to the efficiency indicated by the discharge capacity/charge capacity.

For example, Patent Document 1 discloses a diffraction peak evaluation surface interval measured by using a general-purpose wide-angle X-ray diffraction device, and further evaluates a hexagonal mesh surface (that is, a crystal portion) of carbon in a carbon material by Raman spectroscopy. A technique of a laminated structure and a ratio of an amorphous carbon component or the like. However, in the technique disclosed in Patent Document 1, the crystal structure of the graphite contained in the amorphous material cannot be recognized by the wide-angle X-ray diffraction, and the high charge capacity and discharge capacity of the present invention are not disclosed. A technique for coexisting amorphous/crystalline materials with superior charge and discharge efficiency.

(Patent Document 1) Japanese Patent Laid-Open Publication No. 2006-236752

According to the present invention, it is possible to provide a carbon material for a lithium ion secondary battery of a lithium ion battery which is excellent in charge capacity, discharge capacity, charge capacity, discharge capacity, and charge and discharge efficiency. A negative electrode material for a lithium ion secondary battery and a lithium ion secondary battery.

The above objects are achieved by items (1) to (6) below.

(1) A carbon material for a lithium ion secondary battery having an average interplanar spacing d of 3.40 obtained by a wide-angle X-ray diffraction method according to the following conditions (A) to (E): 3.40 Above, 3.90 Hereinafter, the size Lc of the crystallizer in the c-axis direction is 8 Above, 50 The following amorphous structure has a (002) plane spacing d of 3.25 Above, less than 3.40 Graphite structure;

(A) Light source: Synchrotron radiation

(B) Large Debye-Scherrer camera, camera radius: 286.48mm

(C) Beam size: vertical 0.3mm × horizontal 3.0mm

(D) Detector: image plate (50μm = 0.01°)

(E) Incident X-ray: Wavelength 1.0 (12.4keV).

(2) A carbon material for a lithium ion secondary battery, which is a diffraction pattern measured by a wide-angle X-ray diffraction method under the following conditions (A) to (E), and has a (002) plane calculated by a Bragg method. The average face spacing d is 3.4 Above, 3.9 Hereinafter, the size Lc of the crystallizer in the c-axis direction is 8 Above, 50 The peak of the diffraction pattern below, and the above-mentioned peak has a surface spacing d of 3.25 Above, 3.45 The peak of the (002) plane of the graphite structure below;

(A) Light source: Synchrotron radiation

(B) Large Debye-Scheller camera, camera radius: 286.48mm

(C) Beam size: vertical 0.3mm × horizontal 3.0mm

(D) Detector: image plate (50μm = 0.01°)

(E) Incident X-ray: Wavelength 1.0 (12.4keV).

(3) The carbon material for a lithium ion secondary battery according to the above (1) or (2), wherein the specific surface area obtained by the BET three-point method of nitrogen adsorption is 15 m ² /g or less and 1 m ² /g or more.

(4) The carbon material for a lithium ion secondary battery according to any one of the above (1), wherein the carbon material contains 95% by weight or more and contains 0.5% by weight or more and 5% by weight or less of the nitrogen atom as carbon. An element other than an atom.

(5) A negative electrode material for a lithium ion secondary battery, which comprises the carbon material for a lithium ion secondary battery according to any one of the above (1) to (4).

(6) A lithium ion secondary battery comprising the negative electrode material for a lithium ion secondary battery according to (5) above.

(7) A method for producing a negative electrode material for a lithium ion secondary battery, comprising: 100 parts by weight of a carbon material for a lithium ion secondary battery of the above (1) or (2), 1 to 30 parts by weight of a binder, and viscosity adjustment The mixture is kneaded with 10 to 400 parts by weight of a solvent to obtain a mixture as a slurry or a paste.

(8) The method for producing a negative electrode material for a lithium ion secondary battery according to the above (7), wherein the mixture further contains an additive.

(9) A method for producing a negative electrode for a lithium ion secondary battery, comprising the steps of: molding a mixture produced by the production method of (7), and collecting a volume obtained by collecting the obtained molded body and a negative electrode to obtain a negative electrode; Or a step of applying the above mixture as a negative electrode material to a negative electrode current collector to obtain a negative electrode.

According to the present invention, it is possible to provide a carbon material for a lithium ion secondary battery, a negative electrode material for a lithium ion secondary battery, and a lithium ion secondary battery which can provide a lithium ion battery having high charge and discharge efficiency and high charge capacity and discharge capacity.

Preferred embodiments of the present invention are described below, but the present invention is not limited to these examples. Additions, omissions, substitutions, and other modifications can be made without departing from the scope of the invention.

Hereinafter, Embodiment 1 of the present invention will be described based on the drawings.

(Carbon material for lithium ion secondary battery)

First, an outline of a carbon material for a lithium ion secondary battery of the present invention (hereinafter sometimes referred to as a carbon material) will be described.

The carbon material for a lithium ion secondary battery of the present invention has an average interplanar spacing d of 3.00 obtained by a wide-angle X-ray diffraction method under the following conditions (A) to (E) of 3.40. Above, 3.90 Hereinafter, the size Lc of the crystallizer in the c-axis direction is 8 Above, 50 The following amorphous structure has a (002) plane spacing d of 3.25 Above, less than 3.40 Graphite structure;

(A) Light source: Synchrotron radiation

(B) Large Debye-Scheller camera, camera radius: 286.48mm

(C) Beam size: vertical 0.3mm × horizontal 3.0mm

(D) Detector: image plate (50μm = 0.01°)

(E) Incident X-ray: Wavelength 1.0 (12.4keV).

Next, the carbon material for a lithium ion secondary battery will be described in detail.

The raw material or precursor used in the carbon material for a lithium ion secondary battery is not particularly limited, and is preferably a petroleum crucible or a bitumen produced by the production of ethylene, or a coal slag generated during coal dry distillation, and a coal gangue. a heavy component or bitumen which is distilled off by a low-boiling component, a coal smelt obtained by liquefaction of coal, a petroleum system such as asphalt, or a coal-based bismuth or pitch, and further cross-linking the ruthenium, pitch, and the like. Alternatively, a resin or a resin composition such as a thermosetting resin or a thermoplastic resin may be carbonized, and a resin or a resin composition described later is particularly preferred. In addition, the above-mentioned crosslinked product of the sputum, the bitumen, or the like obtained from petroleum, coal, or the like is also included in the generalized resin or resin composition of the present invention, and these may be used alone or in combination of two or more.

In addition, as described later, the resin composition may contain the above-mentioned resin as a main component, and may contain a curing agent, an additive, and the like.

Here, the thermosetting resin is not particularly limited, and examples thereof include a phenol resin such as a novolac type phenol resin and a resol type phenol resin, and an epoxy resin such as a bisphenol type epoxy resin or a novolak type epoxy resin. Resin, melamine resin, urea resin, aniline resin, cyanate resin, furan resin, ketone resin, unsaturated polyester resin, urethane resin, and the like. Further, it is also possible to use a modified substance which has been modified by various components.

Further, the thermoplastic resin is not particularly limited, and examples thereof include polyethylene, polystyrene, polyacrylonitrile, acrylonitrile-styrene (AS) resin, and acrylonitrile-butadiene-styrene (ABS) resin. Polypropylene, vinyl chloride, methacrylic resin, polyethylene terephthalate, polyamine, polycarbonate, polyacetal, polyphenylene ether, polybutylene terephthalate, polyphenylene , polyfluorene, polyether oxime, polyetheretherketone, polyether quinone imine, polyamidimide, polyimine, polyamine, and the like.

The resin which is a main component used in the carbon material of the present invention is preferably a thermosetting resin. Thereby, the residual carbon ratio of the carbon material can be further improved.

The thermosetting resin is preferably selected from the group consisting of a novolac type phenol resin, a resol type phenol resin, a cyanuric resin, a furan resin, and an aniline resin, and the like. In this way, the design freedom of carbon materials can be broadened and can be manufactured at a low price.

Further, when a thermosetting resin is used, a curing agent may be used in combination.

The curing agent to be used herein is not particularly limited. For example, a phenol novolak type phenol resin may be hexamethylenetetramine, a resol type phenol resin, polyacetal or polyacetal. Further, in the case of an epoxy resin, a polyamine compound such as an aliphatic polyamine or an aromatic polyamine, an acid anhydride, an imidazole compound, a dicyandiamide, a novolac type phenol resin, a bisphenol type phenol resin, or a resol type can be used. A known curing agent such as an epoxy resin such as a phenol resin.

Even in the case of a thermosetting resin in which a predetermined amount of a curing agent is used in combination, a resin composition used in the present invention may be used in a smaller amount or in a combination of a curing agent.

Further, in the resin composition used in the present invention, an additive may be formulated.

The additive to be used herein is not particularly limited, and examples thereof include carbonaceous precursors which are carbonized at 200 to 800 ° C, organic acids, inorganic acids, nitrogen-containing compounds, oxygen-containing compounds, aromatic compounds, and non-ferrous metal elements. Wait.

The above-mentioned additives may be used singly or in combination of two or more kinds depending on the kind and properties of the resin to be used.

The resin used for the carbon material of the present invention may contain a nitrogen-containing resin to be described later as a main component resin. In addition, when the nitrogen-containing resin is not contained in the main component resin, at least one or more nitrogen-containing compounds may be contained as a component other than the main component resin, or a nitrogen-containing resin may be contained as a main component resin and may be contained as a main component. A nitrogen-containing compound of a component other than the component resin. By carbonizing the resin, a carbon material containing nitrogen can be obtained.

Here, as the nitrogen-containing resin, the following may be exemplified.

Examples of the thermosetting resin include a melamine resin, a urea resin, an aniline resin, a cyanate resin, a urethane resin, a phenol resin modified with a nitrogen-containing component such as an amine, an epoxy resin, and the like.

Examples of the thermoplastic resin include polyacrylonitrile, acrylonitrile-styrene (AS) resin, acrylonitrile-butadiene-styrene (ABS) resin, polyamine, polyether decylamine, and polyamidoxime. Amine, polyimine, polyamine, and the like.

In addition, the resin other than the nitrogen-containing resin may be exemplified as follows.

Examples of the thermosetting resin include a phenol resin, an epoxy resin, a furan resin, and an unsaturated polyester resin.

Examples of the thermoplastic resin include polyethylene, polystyrene, polypropylene, vinyl chloride, methacrylic resin, polyethylene terephthalate, polyamine, polycarbonate, polyacetal, and polyacetal. Alkyl ether, polybutylene terephthalate, polyphenyl hydrazine, polyfluorene, polyether oxime, polyether ether ketone, and the like.

In addition, when a nitrogen-containing compound is used as a component other than the main component resin, the type thereof is not particularly limited, and for example, hexamethylenetetramine which is a hardener of a novolak-type phenol resin, which is hardened by an epoxy resin, can be used. The aliphatic polyamine, the aromatic polyamine, the dicyandiamide or the like of the agent; in addition to the hardener component, a nitrogen-containing compound such as an amine compound, an ammonium salt, a nitrate or a nitro compound which does not have a curing agent function can be used.

As the nitrogen-containing compound, one type may be used, or two or more types may be used in combination, with or without a nitrogen-containing resin.

The resin composition used in the carbon material of the present invention or the nitrogen content in the resin is not particularly limited, but is preferably 5 to 65% by weight. More preferably, it is 10 to 20% by weight.

By carrying out the carbonization treatment of the resin composition or the resin, the carbon atom content in the finally obtained carbon material is preferably 95% by weight or more, and the nitrogen atom content is preferably 0.5 to 5% by weight. The carbon atom content is more preferably 96% by weight or more.

When the nitrogen atom is contained in an amount of 0.5% by weight or more, particularly preferably 1.0% by weight or more, the electrical property of nitrogen can be imparted to the carbon material to impart preferable electrical characteristics. Thereby, the absorption/release of lithium atoms is promoted, and high charge and discharge characteristics can be imparted.

In addition, when the nitrogen atom is made 5% by weight or less, and particularly preferably 3% by weight or less, it is possible to suppress an excessively strong electrical property imparted to the carbon material, and to prevent electrosorption of the occluded lithium ions and nitrogen atoms. Thereby, an increase in irreversible capacity can be suppressed, and high charge and discharge characteristics can be obtained.

The nitrogen content in the carbon material of the present invention may be determined by appropriately setting conditions for carbonizing the resin composition or resin, or by performing carbonization treatment, in addition to the nitrogen content of the resin composition or the resin. The conditions such as hardening treatment or pre-carbonization treatment are adjusted.

For example, as a method of obtaining the carbon material having the above-described nitrogen content, for example, a method in which the nitrogen content of the resin composition or the resin is a predetermined value and the conditions for carbonization treatment, particularly the final temperature, are adjusted .

The preparation method of the resin composition used for the carbon material of the present invention is not particularly limited, and for example, it can be prepared by blending the above-mentioned main component resin and other components at a predetermined ratio and melting and mixing the same. Method; a method in which the components are dissolved in a solvent and mixed; or a method in which the components are pulverized and mixed.

In the carbon material, the nitrogen content is measured by a thermal conductivity method.

In this method, after the measurement sample is converted into a simple gas (CO ₂ , H ₂ O, and N ₂ ) by a combustion method, the vaporized sample is homogenized and passed through a column. Thereby, these gases are separated stepwise, and the contents of carbon, hydrogen and nitrogen can be measured from the respective thermal conductivity.

In the present invention, it is carried out using an elemental analysis measuring device "PE2400" manufactured by Perkin Elmer Co., Ltd.

Further, the carbon material of the present invention is obtained by a wide-angle X-ray diffraction method according to the following conditions (A) to (E) as shown in Fig. 1 (diffraction by wide-angle X-ray diffraction method) The average face spacing d of the (002) plane of the pattern, calculated using the Bragg formula, is 3.40 Above, 3.90 Hereinafter, the size Lc of the crystallizer in the c-axis direction is 8 Above, 50 The following amorphous structure (the peak of the diffraction pattern) and having a (002) plane spacing d of 3.25 Above, less than 3.40 a carbon material for a lithium ion secondary battery of a graphite structure (the peak of the (002) plane);

(A) Light source: Synchrotron radiation

(B) Large Debye-Scheller camera, camera radius: 286.48mm

(C) Beam size: vertical 0.3mm × horizontal 3.0mm

(D) Detector: image plate (50μm = 0.01°)

(E) Incident X-ray: Wavelength 1.0 (12.4keV).

The plane spacing d of the (002) plane is derived from the diffraction angle (reflection angle of the spectrum) θ by a parabolic approximation method, that is, by a parabola of any number of points near the vertex of the peak, by using the least squares method as the peak. The method of the vertex is determined and calculated using the Bragg formula described below.

λ=2d _hk1 Sinθ Bragg (d _hk1 =d002)

λ: incident X-ray wavelength

θ: the angle of reflection of the spectrum

The carbon material of the present invention belongs to having an average surface spacing d with a (002) plane of 3.40. Above, 3.90 Hereinafter, the size Lc of the crystallizer in the c-axis direction is 8 Above, 50 The following amorphous structure has a (002) plane spacing d of 3.25 Above, less than 3.40 Since the material of the graphite structure is characterized by an amorphous structure having an average interplanar spacing of the size at which lithium can easily enter and exit, the charge capacity and the discharge capacity can be improved. The average interplanar spacing d of the (002) plane in the amorphous structure is preferably 3.45. Above, less than 3.85 . Further, since the graphite structure is formed in the amorphous structure, lithium ions can be smoothly collected/disengaged, so that the charge capacity and the discharge capacity can be increased and the charge and discharge efficiency can be improved.

The wide-angle X-ray diffraction method is known as a technique for analyzing the structure of a carbon material, and in the present invention, a wide-angle X-ray diffraction method using synchronous radiation obtained by SPring-8 using a high-intensity optical science research center is used. A measurement method having an extremely high decomposition energy can specify a graphite structure which is unknown in the past and exists in amorphous carbon. According to the present technology, the inventors of the present invention have attained a material which can develop a high charge and discharge efficiency which is the subject of the present invention and which can realize a high charge capacity and a discharge capacity.

Further, in the carbon material of the present invention, the average interplanar spacing d of the (002) plane is 3.40. Above, 3.90 The following can be done, especially at 3.60 In the above case, interlayer shrinkage/expansion due to absorption of lithium ions is less likely to occur, so that it is possible to further suppress a decrease in charge/discharge cycle property, which is preferable.

On the other hand, especially the average surface spacing d of the above (002) plane is 3.80 In the following case, the storage/disengagement of lithium ions proceeds smoothly, and the decrease in charge and discharge efficiency can be further suppressed, which is preferable.

Further, the carbon material of the present invention preferably has a crystallite size Lc of 8 in the c-axis direction (the (002) plane orthogonal direction). Above, 50 the following.

By setting Lc to 8 Above, especially 9 As described above, a carbon interlayer space capable of occluding/desorbing lithium ions is formed, and an effect of obtaining a sufficient charge and discharge capacity can be obtained. In addition, by setting to 50 Following, especially 15 In the following, it is possible to suppress the collapse of the carbon laminated structure due to the absorption/desorption of lithium ions or the reductive decomposition of the electrolytic solution, and it is possible to suppress the decrease in the charge and discharge efficiency and the charge and discharge cycle property.

Lc was calculated as follows.

The half value width of the (002) plane peak and the diffraction angle (reflection angle of the spectrum) of the amorphous structure in the spectrum obtained by the wide-angle X-ray diffraction measurement were determined using the following Scherrer equation.

Lc=0.94λ/(βcosθ) (Scherrer type)

Lc: size of crystallizer

λ: incident X-ray wavelength

β: half value width of the peak (in radians)

θ: the angle of reflection of the spectrum

Further, in the carbon material of the present invention, the specific surface area obtained by the BET three-point method of nitrogen adsorption is preferably 15 m ² /g or less and 1 m ² /g or more. The specific surface area obtained by the BET three-point method of nitrogen adsorption is more preferably 10 m ² /g or less and 1 m ² /g or more.

When the specific surface area obtained by the BET three-point method of nitrogen adsorption is 15 m ² /g or less, the reaction between the carbon material and the electrolytic solution can be suppressed.

In addition, when the specific surface area obtained by the BET three-point method of nitrogen adsorption is 1 m ² /g or more, the effect of obtaining an appropriate permeability of the electrolytic solution to the carbon material can be obtained.

The method of calculating the specific surface area is as follows.

The single molecule adsorption amount Wm is calculated by the following formula (1), and the total surface area Stotal is calculated by the following formula (2), and the specific surface area S is obtained by the following formula (3).

1/[W(Po/P-1)=(C-1)/WmC(P/Po)/WmC ...(1)

In the formula (1), P: the gas pressure of the adsorbate under adsorption equilibrium, Po: the saturated vapor pressure of the adsorbate at the adsorption temperature, W: the adsorption amount under the equilibrium pressure P, Wm: the adsorption amount of the monolayer, C: constant relating to the interaction between the solid surface and the adsorbate (C=exp{(E1-E2)RT}) [E1: heat of adsorption of the first layer (kJ/mol), E2: measured temperature of the adsorbate Liquefied heat (kJ/mol)

Stotal=(WmNAcs)M ...(2)

In the formula (2), N: Yafotine number, M: molecular weight, Acs: adsorption sectional area

S=Stotal/w ...(3)

In formula (3), w: sample weight (g)

The above carbon material can be produced as follows.

First, a resin or a resin composition to be carbonized is produced.

The apparatus for preparing the resin composition is not particularly limited. For example, when performing melt mixing, a kneading device such as a kneading roll or a uniaxial or biaxial kneader can be used. Further, when dissolving and mixing, a mixing device such as a Hanschel mixer or a dosing device can be used. When pulverizing and mixing is carried out, for example, a device such as a honing machine or a jet mill can be used.

The resin composition thus obtained is also a material in which only a plurality of components are physically mixed, or a mechanical energy imparted by mixing (stirring, kneading, etc.) during the preparation of the resin composition and Converting the heat energy to a part of the chemical reaction. Specifically, it can be subjected to a mechanochemical reaction caused by mechanical energy and a chemical reaction caused by thermal energy.

The carbon material of the present invention is obtained by subjecting the above resin composition or resin to carbonization treatment. Moreover, the term "carbonization treatment" refers to a step of heating the resin composition to increase the carbon atom content ratio.

Here, the conditions for the carbonization treatment are not particularly limited, and for example, the temperature can be raised from 1 to 200 ° C /hr at normal temperature, and the temperature is maintained for 0.1 to 50 hours, preferably 0.5 to 10 hours. The environment in the case of the carbonization treatment is preferably carried out under an inert atmosphere such as nitrogen or helium, or in a substantially inert atmosphere in the presence of a trace amount of oxygen in an inert gas, or in a reducing gas atmosphere. Thereby, thermal decomposition (oxidative decomposition) of the resin is suppressed, and a desired carbon material can be obtained.

The conditions such as temperature and time during the carbonization treatment can be appropriately adjusted to optimize the characteristics of the carbon material.

The pre-carbonization treatment may be performed before the carbonization treatment described above. The pre-carbonization treatment refers to a step of heat-treating at a temperature lower than the carbonization treatment so that the resin does not melt.

Here, the conditions for the pre-carbonization treatment are not particularly limited, and for example, it can be carried out at 200 to 600 ° C for 1 to 10 hours. By performing the pre-carbonization treatment before the carbonization treatment, even when the resin composition or the resin is not melted, the resin composition or the resin is pulverized before the carbonization treatment step, and the resin composition after the pulverization can be prevented. Or the remelting of the resin during the carbonization treatment can efficiently obtain the desired carbon material.

At this time, the average interplanar spacing d having the (002) plane for obtaining the present invention is 3.40. Above, 3.90 Hereinafter, the size Lc of the crystallizer in the c-axis direction is 8 Above, 50 The following amorphous structure has a (002) plane spacing d of 3.25 Above, less than 3.40 An example of the method of the carbon material for a lithium ion secondary battery of a graphite structure is, for example, a pre-carbonization treatment in a state where a reducing gas or an inert gas is not present.

In addition, when a thermosetting resin or a polymerizable polymer compound is used as the resin constituting the carbon material, the resin composition or the resin may be subjected to a curing treatment before the pre-carbonization treatment.

The curing treatment method is not particularly limited. For example, it can be thermally cured by applying heat to a resin composition to a curing reaction, or a method of using a resin and a curing agent in combination. Thereby, since the pre-carbonization treatment can be performed in accordance with the solid phase, the carbonization treatment or the pre-carbonization treatment can be performed while maintaining the resin structure to a certain extent, and the structure or characteristics of the carbon material can be controlled.

When the carbonization treatment or the pre-carbonization treatment is performed, a metal, a pigment, a lubricant, an antistatic agent, an antioxidant, or the like may be added to the resin composition to impart desired properties to the carbon material.

When the hardening treatment and/or the pre-carbonization treatment are performed, the processed material may be pulverized before the carbonization treatment. In this case, the unevenness of the heat history during the carbonization treatment can be reduced, and the uniformity of the surface state of the carbon material can be improved. Moreover, the handleability of the processed material can be made good.

Furthermore, in order to obtain the present invention, the average interplanar spacing d with the (002) plane is 3.40. Above, 3.90 Hereinafter, the size Lc of the crystallizer in the c-axis direction is 8 Above, 50 The following amorphous structure has a (002) plane spacing d of 3.25 Above, less than 3.40 The carbon material for a lithium ion secondary battery of a graphite structure is naturally cooled (cooled) to 800 to 500 ° C in the presence of a reducing gas or an inert gas, and thereafter, at 20 ° C / hour or more and 500 ° C / hour or less. Cooling is carried out to 200 ° C or lower, preferably 100 ° C or lower.

It is presumed that if the cooling is carried out under the conditions within the above range, the cooling rate is faster than the natural cooling, and a specific structure containing a graphite structure is appropriately formed in the amorphous structure, and the carbon material of the present invention is obtained.

(Lithium ion secondary battery)

Next, an embodiment of a negative electrode material for a secondary battery of the present invention (hereinafter sometimes referred to as a "negative electrode material") and a lithium ion secondary battery (hereinafter sometimes referred to as a "secondary battery") using an embodiment thereof Be explained.

Fig. 2 is a schematic view showing a configuration of an embodiment of a secondary battery.

The secondary battery 10 includes a negative electrode 13 composed of a negative electrode material 12 and a negative electrode current collector 14, a positive electrode 21 composed of a positive electrode material 20 and a positive electrode current collector 22, an electrolytic solution 16, and a separator 18.

In the negative electrode 13, for example, a copper foil or a nickel foil can be used as the negative electrode current collector 14. The negative electrode material 12 is a carbon material of the present invention.

The negative electrode material of the present invention is produced, for example, as follows.

To 100 parts by weight of the carbon material, a binder (containing a fluorine-based polymer such as polyethylene or polypropylene, an acrylic resin, a polyimide, a rubber polymer such as butyl rubber or butadiene rubber, or the like) is added. 1 to 30 parts by weight, a solvent for viscosity adjustment (N-methyl-2-pyrrolidone, dimethylformamide, water, etc.) 10 to 400 parts by weight, and an appropriate amount of additives (dispersant, conductive material, etc.) Further, the mixture is kneaded, and the mixture of the paste is formed into a sheet shape, a pellet shape, or the like by compression molding, roll molding, or the like, whereby the negative electrode material 12 can be obtained.

The negative electrode 13 can be produced by laminating with the negative electrode current collector 14.

In addition, a binder (a fluorine-based polymer such as polyethylene or polypropylene, an acrylic resin, a polyimide, a rubber polymer such as butyl rubber or butadiene rubber) is added to 100 parts by weight of the carbon material. (1) 30 parts by weight and an appropriate amount of a solvent for viscosity adjustment (N-methyl-2-pyrrolidone, dimethylformamide, water, etc.) and kneaded, and used a mixture as a slurry to serve as a negative electrode. The material 12 is coated or formed on the negative electrode current collector 14, whereby the negative electrode 13 can also be produced.

The electrolyte solution 16 is used in a non-aqueous solvent in which a lithium salt which is an electrolyte is dissolved.

As the nonaqueous solvent, a cyclic ester such as propylene carbonate, ethylene carbonate or γ-butyrolactone, a chain ester such as dimethyl carbonate or diethyl carbonate, or dimethoxy B can be used. a mixture of a chain ether such as an alkane or the like.

As the electrolyte, a lithium metal salt such as LiClO ₄ or LiPF ₆ or a tetraalkylammonium salt can be used. Further, the above salts may be used in a mixture of polyethylene oxide, polyacrylonitrile or the like to form a solid electrolyte.

The separator 18 is not particularly limited, and for example, a porous film such as polyethylene or polypropylene, a nonwoven fabric or the like can be used.

In the positive electrode 21, the positive electrode material 20 is not particularly limited, and for example, a composite oxide such as lithium cobalt oxide (LiCoO ₂ ), lithium nickel oxide (LiNiO ₂ ), or lithium manganese oxide (LiMn ₂ O ₄ ) can be used. Or a conductive polymer such as polyaniline or polypyrrole.

As the positive electrode current collector 22, for example, an aluminum foil can be used.

The positive electrode 21 of the present embodiment can be produced by a known method for producing a positive electrode.

The present invention is not limited to the above-described embodiments, and modifications, improvements, etc. within the scope of the object of the invention are also included in the present invention.

Next, a second embodiment of the present invention will be described based on the drawings. Further, in the second embodiment of the present invention, the point is not described in the same manner as in the first embodiment.

(Carbon material for lithium ion secondary battery)

First, an outline of a carbon material for a lithium ion secondary battery of the present invention (hereinafter sometimes referred to as a carbon material) will be described.

The carbon material for a lithium ion secondary battery of the present invention has a diffraction pattern measured by a wide-angle X-ray diffraction method under the following conditions (A) to (E), and has a (002) plane calculated by a Bragg equation. The average face spacing d is 3.4 Above, 3.9 Hereinafter, the size Lc of the crystallizer in the c-axis direction is 8 Above, 50 The peak of the diffraction pattern below, and the above-mentioned peak has a surface spacing d of 3.25 Above, 3.45 The peak of the (002) plane of the graphite structure below;

(A) Light source: Synchrotron radiation

(B) Large Debye-Scheller camera, camera radius: 286.48mm

(C) Beam size: vertical 0.3mm × horizontal 3.0mm

(D) Detector: image plate (50μm = 0.01°)

(E) Incident X-ray: Wavelength 1.0 (12.4keV).

Further, the carbon material of the present invention is a diffraction pattern measured by a wide-angle X-ray diffraction method under the following conditions (A) to (E) as shown in Fig. 1, and is calculated using a Bragg formula ( 002) The average face spacing d of the face is 3.4 Above, 3.9 Hereinafter, the size Lc of the crystallizer in the c-axis direction is 8 Above, 50 The peak of the diffraction pattern below, and the above-mentioned peak has a surface spacing d of 3.25 Above, 3.45 a carbon material for a lithium ion secondary battery having a peak of a (002) plane of a graphite structure;

(A) Light source: Synchrotron radiation

(B) Large Debye-Scheller camera, camera radius: 286.48mm

(C) Beam size: vertical 0.3mm × horizontal 3.0mm

(D) Detector: image plate (50μm = 0.01°)

(E) Incident X-ray: Wavelength 1.0 (12.4keV).

The carbon material of the present invention has "having an average surface spacing d of 3.4". Above, 3.9 Hereinafter, the size Lc of the crystallizer in the c-axis direction is 8 Above, 50 The following peak of the diffraction pattern according to the amorphous structure, and having a surface spacing d of 3.25 in the above peak Above, 3.45 Since the following features of the (002) plane peak of the graphite structure are formed, an amorphous structure having an average surface spacing of a size in which lithium can easily enter and exit is formed, and the charge capacity and discharge capacity can be improved. The average interplanar spacing d of the (002) plane in the amorphous structure is preferably 3.45. Above, 3.85 the following. Further, since the graphite structure is formed in the amorphous structure, lithium ions can be smoothly collected/disengaged, so that the charge capacity and the discharge capacity can be increased and the charge and discharge efficiency can be improved.

The wide-angle X-ray diffraction method is known as a technique for analyzing a carbon material structure, and in the present invention, it can be specified by using a measurement method which is a wide-angle X-ray diffraction method using synchronous radiation and having extremely high decomposition energy. A graphite structure that was previously unknown in amorphous carbon. According to the present technology, the inventors of the present invention have attained a material which can develop a high charge and discharge efficiency which is the subject of the present invention and which can realize a high charge capacity and a discharge capacity.

In the wide-angle X-ray diffraction method of the present invention, synchronous emission light is used, and as the electron energy, a radiation light facility (device) capable of obtaining 1 GeV or more, more preferably 7 GeV or more can be used. As such a facility (device), PF of the high-energy accelerator research machine in Japan, SPring-8 of the high-intensity optical science research center, APS of the Argonne National Laboratory in the United States, and USRLS of the European Union (EU) can be exemplified. SPring-8, APS, USRLS.

Further, in the carbon material of the present invention, the average interplanar spacing d of the (002) plane is 3.4. Above, 3.9 The following can be done, especially at 3.6 In the above case, interlayer shrinkage/expansion due to absorption of lithium ions is less likely to occur, so that it is possible to further suppress a decrease in charge/discharge cycle property, which is preferable.

On the other hand, especially the average surface spacing d of the above (002) plane is 3.8. In the following case, the storage/disengagement of lithium ions proceeds smoothly, and the decrease in charge and discharge efficiency can be further suppressed, which is preferable.

Further, the carbon material of the present invention preferably has a crystallite size Lc of 8 in the c-axis direction (the (002) plane orthogonal direction). Above, 50 the following.

By setting Lc to 8 Above, especially 9 As described above, a carbon interlayer space capable of occluding/desorbing lithium ions is formed, and an effect of obtaining a sufficient charge and discharge capacity can be obtained. In addition, by setting to 50 Following, especially 15 In the following, it is possible to suppress the collapse of the carbon laminated structure due to the absorption/desorption of lithium ions or the reductive decomposition of the electrolytic solution, and it is possible to suppress the decrease in the charge and discharge efficiency and the charge and discharge cycle property.

Lc was calculated as follows.

The half value width and the diffraction angle of the (002) plane peak of the amorphous structure in the spectrum obtained from the wide-angle X-ray diffraction measurement were determined using the following Scherrer equation.

Lc=0.94λ/(βcosθ) (Scherrer type)

Lc: size of crystallizer

λ: incident X-ray wavelength

β: half value width of the peak (in radians)

θ: the angle of reflection of the spectrum

The carbon material of the present invention is obtained by subjecting the above resin composition or resin to carbonization treatment.

Here, the conditions for the carbonization treatment are not particularly limited. For example, the temperature can be raised from 1 to 200 ° C /hr at normal temperature, and from 0.1 to 50 hours, preferably from 0.5 to 10 hours at 800 to 3000 ° C. The environment in the case of the carbonization treatment is preferably carried out under an inert atmosphere such as nitrogen or helium, or in a substantially inert atmosphere in the presence of a trace amount of oxygen in an inert gas, or in a reducing gas atmosphere. Thereby, thermal decomposition (oxidative decomposition) of the resin is suppressed, and a desired carbon material can be obtained.

The conditions such as temperature and time during the carbonization treatment can be appropriately adjusted to optimize the characteristics of the carbon material.

The pre-carbonization treatment may be performed before the carbonization treatment described above.

Here, the conditions for the pre-carbonization treatment are not particularly limited, and for example, it can be carried out at 200 to 600 ° C for 1 to 10 hours. By performing the pre-carbonization treatment before the carbonization treatment, even when the resin composition or the resin is not melted, the resin composition or the resin is pulverized before the carbonization treatment step, and the resin composition after the pulverization can be prevented. Or the remelting of the resin during the carbonization treatment can efficiently obtain the desired carbon material.

At this time, the average interplanar spacing d for obtaining the (002) plane having the Bragg equation used was 3.4. Above, 3.9 Hereinafter, the size Lc of the crystallizer in the c-axis direction is 8 Above, 50 The peak of the diffraction pattern below, and having a surface spacing d of 3.25 in the above peaks Above, 3.45 An example of the method of the carbon material for a lithium ion secondary battery of the peak of the (002) plane of the graphite structure is a pre-carbonization treatment in a state where no reducing gas or inert gas is present.

When the hardening treatment and/or the pre-carbonization treatment are performed, the processed material may be pulverized before the carbonization treatment. In this case, the unevenness of the heat history during the carbonization treatment can be reduced, and the uniformity of the surface state of the carbon material can be improved. Moreover, the handleability of the processed material can be made good.

Furthermore, in order to obtain an average surface spacing d having a (002) plane calculated using the Bragg equation, it is 3.4. Above, 3.9 Hereinafter, the size Lc of the crystallizer in the c-axis direction is 8 Above, 50 The peak of the diffraction pattern below, and having a surface spacing d of 3.25 in the above peak Above, 3.45 The carbon material for a lithium ion secondary battery of the peak of the (002) plane of the graphite structure may be appropriately selected depending on the raw materials to be used, for example, if necessary, after carbonization treatment, in the presence of a reducing gas or an inert gas. It is naturally cooled to 800 to 500 ° C, and thereafter, it is cooled to 100 ° C or lower at 100 ° C / hour.

In this case, it is presumed that the cooling rate is in an appropriate state, and a specific structure including a graphite structure is appropriately formed in the amorphous structure, and the carbon material of the present invention is obtained.

Among them, the present invention is characterized in that even if graphite or a graphitized catalyst is not used in the raw material or precursor used, a diffraction pattern measured by a wide-angle X-ray diffraction method can be obtained, which has a Bragg type. The calculated average surface spacing d of the (002) plane is 3.4. Above, 3.9 Hereinafter, the size Lc of the crystallizer in the c-axis direction is 8 Above, 50 The peak of the diffraction pattern below, and the above-mentioned peak has a surface spacing d of 3.25 Above, 3.45 The carbon material for a lithium ion secondary battery of the peak of the (002) plane of the graphite structure below. A material or a precursor, a step, or the like which exhibits the feature is appropriately selected, and it is provided before the aspect of the present invention can be realized, and graphite or the like may be added as an additive as needed.

(Example)

Hereinafter, the present invention will be described by way of examples. However, the invention is not limited to the embodiments. In addition, "parts" shown in the respective examples and comparative examples indicate "parts by weight", and "%" means "% by weight".

First, the measurement methods in the following examples and comparative examples will be described.

(1. Measurement of the surface spacing d of the (002) plane and the size Lc of the crystallizer in the c-axis direction by the synchronized emission light)

Wide-angle X-ray diffraction is carried out by the high-intensity optical science research center (JASRI) large-scale radiation light facilities SPring-8 and BL19B2 according to the following conditions (A) to (E), and the obtained spectrum is evaluated according to the following steps: (002) and the size (Lc) of the crystallizer in the c-axis direction. The diffraction angle (reflection angle of the spectrum) θ is derived by a parabolic approximation method, that is, a parabola passing through any number of points near the apex of the spectral peak by a least squares method, and the vertex is determined as a peak apex.

(A) Light source: Synchrotron radiation

(B) Large Debye-Scheller camera, camera radius: 286.48mm

(C) Beam size: vertical 0.3mm × horizontal 3.0mm

(D) Detector: image plate (50μm = 0.01°)

(E) Incident X-ray: Wavelength 1.0 (12.4keV).

○ (002) plane spacing d

λ=2d _hk1 Sinθ Bragg (d _hk1 =d ₀₀₂ )

λ: incident X-ray wavelength

θ: the angle of reflection of the spectrum

○The size of the crystallizer in the c-axis direction Lc

The half value width of the (002) plane peak and the diffraction angle (reflection angle of the spectrum) θ of the amorphous structure in the spectrum obtained by the wide-angle X-ray diffraction measurement were determined using the following Scherrer equation.

Lc=0.94λ/(βcosθ) (Scherrer type)

Lc: size of crystallizer

λ: incident X-ray wavelength

β: half value width of the peak (in radians)

θ: the angle of reflection of the spectrum

(2. Determination of the average surface spacing d of the (002) plane of the X-ray diffraction device using a conventional laboratory specification)

X-ray diffraction device "XRD-7000" manufactured by Shimadzu Corporation (incident X-ray wavelength CuKα1.54) The plane spacing d of the (002) plane is measured.

(3. Determination of Raman spectroscopy)

Using a RENISHAW InViaReflex Raman microscope, the sample was magnified 20 times to the objective lens, and the sample was irradiated with YAG laser light of 532 nm and 2.5 mW at a wavelength of 5 times, the measurement range was 100 to 2000 cm ^-1 , and the exposure time was 100 seconds. Man scattered light. The resulting spectrum drawn to a base line intensity belongs to Raman spectroscopic spectrum 1300 of the ID ~ D band intensity range 1400cm ^-1 and 1560 ~ G band intensity in a range of 1650cm ^-1 is obtained by the IG of the base line Ratio of R (ID/IG).

(4. Specific surface area)

The measurement was carried out by the BET 3 point method of nitrogen adsorption using a Nova-1200 apparatus manufactured by Yuasa Corporation. The specific calculation method is as described in the above embodiment.

(5. Carbon content, nitrogen content)

The elemental analysis measuring apparatus "PE2400" manufactured by Perkin Elmer Co., Ltd. was used for measurement. After the measurement sample was converted into CO ₂ , H ₂ O, and N ₂ by a combustion method, the vaporized sample was homogenized and passed through a column. Thereby, these gases are separated stepwise, and the contents of carbon, hydrogen and nitrogen can be measured from the respective thermal conductivity. A) Carbon content rate

The obtained carbon material was dried at 110 ° C / vacuum for 3 hours, and then the carbon composition ratio was measured using an elemental analysis measuring device.

B) nitrogen content rate

The obtained carbon material was dried at 110 ° C / vacuum for 3 hours, and then the nitrogen composition ratio was measured using an elemental analysis measuring device.

(6. Charging capacity, discharge capacity, charge and discharge efficiency)

(1) Manufacture of a two-pole coin type battery for secondary battery evaluation

For 100 parts of the carbon materials obtained in each of the examples and the comparative examples, 10 parts of polyvinylidene chloride as a binder, and N-methyl-2-pyrrolidone as a diluent solvent were appropriately added and mixed to prepare a slurry. Negative electrode mixture. The prepared negative electrode slurry mixture was applied to both surfaces of a 18 μm copper foil, and then vacuum dried at 110 ° C for 1 hour. After vacuum drying, the electrode was subjected to press forming by roll pressing. This was cut into a circle having a diameter of 16.156 mm to prepare a negative electrode.

The positive electrode was evaluated using a lithium metal-based two-pole coin type battery. The electrolytic solution was used in a mixture of ethylene polycarbonate and diethyl carbonate in a volume ratio of 1:1 to dissolve 1 mol/liter of lithium perchlorate.

(2) Evaluation of charging capacity and discharge capacity

The charging condition was charged to 1 mV at a constant current of 25 mA/g, and the current was attenuated to 1.25 mA/g at a time of 1 mV as a charging end point. Further, the cutoff potential of the discharge condition was set to 1.5V.

(3) Evaluation of charge and discharge efficiency

According to the value obtained in the above (2), it is calculated by the following formula.

Charge and discharge efficiency (%) = [discharge capacity / charge capacity] x 100

(Example 1)

The phenol resin PR-217 (manufactured by Sumitomo Bakelite Co., Ltd.) as a resin composition was treated in the following steps (a) to (f) to obtain a carbon material.

(a) There is no replacement of reducing gas, replacement of inert gas, circulation of reducing gas, and circulation of inert gas, and the temperature is raised to 500 ° C at 100 ° C / hour from room temperature.

(b) No reduction of reducing gas, replacement of inert gas, circulation of reducing gas, circulation of inert gas, degreasing treatment at 500 ° C for 2 hours, cooling

(c) Fine pulverization by vibration ball milling

(d) Increasing the temperature to 100 ° C / hour from room temperature to 1200 ° C under inert gas (nitrogen) replacement and circulation

(e) Carbonization at 1200 ° C for 8 hours under a flow of inert gas (nitrogen)

(f) After circulating under inert gas (nitrogen), naturally let cool to 600 ° C, and then cool from 100 ° C / hour to 100 ° C from 600 ° C

(Example 2)

In the case of substituting the phenol resin in Example 1, an aniline resin (combined by the following method) was used.

100 parts of aniline, 697 parts of 37% formaldehyde solution, and 2 parts of oxalic acid were placed in a 3-necked flask equipped with a stirring device and a cooling tube, and reacted at 100 ° C for 3 hours, followed by dehydration to obtain 110 parts of an aniline resin. The obtained aniline resin had a weight average molecular weight of about 800.

The resin composition obtained by pulverizing and mixing 100 parts of aniline resin and 10 parts of hexamethylenetetramine obtained as above was treated in the same manner as in Example 1 to obtain a carbon material.

(Comparative Example 1)

A carbon material composed of graphite (intermediate carbon particles) is prepared.

(Comparative Example 2)

In the first embodiment, except for the substituted phenol resin, it was changed to coal tar pitch (manufactured by JFE Corporation), and the steps (d), (e), and (f) were changed as follows, and the rest were the same as in the first embodiment. The steps are processed to obtain a carbon material.

(d) The temperature is raised to 1100 ° C at 100 ° C / hour from room temperature under inert gas (nitrogen) replacement and circulation.

(e) Carbonized at 1100 ° C for 4 hours under an inert gas (nitrogen) flow

(f) naturally let cool to 100 ° C under the circulation of inert gas (nitrogen)

(Comparative Example 3)

In the first embodiment, except that the steps (d), (e), and (f) were changed as follows, the same procedures as in the first embodiment were carried out to obtain a carbon material.

(d) The temperature is raised to 1000 ° C at 100 ° C / hour from room temperature under inert gas (nitrogen) replacement and circulation.

(e) Carbonized at 1000 ° C for 8 hours under an inert gas (nitrogen) flow

(f) naturally let cool to 100 ° C under the circulation of inert gas (nitrogen)

The evaluation results of the carbon materials obtained in the above Examples and Comparative Examples and the measurement results of the charge capacity, the discharge capacity, and the charge and discharge efficiency when the carbon material was used as the negative electrode are shown in Table 1.

The average interplanar spacing d with the (002) plane belonging to the present invention is 3.40 Above, 3.90 Hereinafter, the size Lc of the crystallizer in the c-axis direction is 8 Above, 50 The following amorphous structure has a (002) plane spacing d of 3.25 Above, less than 3.40 In Examples 1 and 2 of the carbon material for a lithium ion secondary battery having a graphite structure, both of the charging capacity and the discharge capacity were high, and the charge and discharge efficiency was also high.

In Comparative Example 1 which does not have an amorphous halo pattern according to an amorphous structure, although the efficiency is high, both the charge capacity and the discharge capacity are low values. Further, in the wide-angle X-ray diffraction method of the synchronized emission light of the present invention, in Comparative Example 2 which belongs only to the amorphous halo pattern of the amorphous structure but does not have the (002) plane peak of the graphite structure, The charging capacity and the discharge capacity were high, but the efficiency was low. In Comparative Example 3, the discharge capacity and efficiency were lower than those in the examples.

In addition, when wide-angle X-ray diffraction using a conventional laboratory-scale device was used, 3.25 of the example was not detected. Above, less than 3.40 The plane spacing d of the graphite structure.

Further, the Raman spectra of the first embodiment and the second and third comparative examples which are based on the amorphous structure are not greatly different, and the characteristics of the material belonging to the present invention cannot be specified by Raman spectroscopy. It is a crystalline structure derived from graphite present in amorphous carbon.

(Example 3)

The phenol resin PR-217 (manufactured by Sumitomo Bakelite Co., Ltd.) as a resin composition was treated in the following steps (a) to (f) to obtain a carbon material.

(a) There is no replacement of reducing gas, replacement of inert gas, circulation of reducing gas, and circulation of inert gas, and the temperature is raised to 500 ° C at 100 ° C / hour from room temperature.

(b) No reduction of reducing gas, replacement of inert gas, circulation of reducing gas, circulation of inert gas, degreasing treatment at 500 ° C for 2 hours, cooling

(c) Fine pulverization by vibration ball milling

(d) Increasing the temperature to 100 ° C / hour from room temperature to 1200 ° C under inert gas (nitrogen) replacement and circulation

(e) Carbonization at 1200 ° C for 8 hours under a flow of inert gas (nitrogen)

(f) After circulating under inert gas (nitrogen), naturally let cool to 600 ° C, and then cool from 100 ° C / hour to 100 ° C from 600 ° C

(Example 4)

In the case of substituting the phenol resin in Example 3, an aniline resin (combined by the following method) was used.

100 parts of aniline, 697 parts of 37% formaldehyde solution, and 2 parts of oxalic acid were placed in a 3-necked flask equipped with a stirring device and a cooling tube, and reacted at 100 ° C for 3 hours, followed by dehydration to obtain 110 parts of an aniline resin. The obtained aniline resin had a weight average molecular weight of about 800.

The resin composition obtained by pulverizing 100 parts of aniline resin and 10 parts of hexamethylenetetramine obtained as described above was treated in the same manner as in Example 3 to obtain a carbon material.

(Comparative Example 4)

A carbon material composed of graphite (intermediate carbon particles) is prepared.

(Comparative Example 5)

In the third embodiment, except for the substituted phenol resin, the coal tar pitch (manufactured by JFE Corporation) was changed, and the steps (d), (e), and (f) were changed as follows, and the rest were the same as in the first embodiment. The steps are processed to obtain a carbon material.

(d) The temperature is raised to 1100 ° C at 100 ° C / hour from room temperature under inert gas (nitrogen) replacement and circulation.

(e) Carbonized at 1100 ° C for 4 hours under an inert gas (nitrogen) flow

(f) naturally let cool to 100 ° C under the circulation of inert gas (nitrogen)

The evaluation results of the carbon materials obtained in the above Examples and Comparative Examples and the measurement results of the charging capacity, the discharge capacity, and the charge and discharge efficiency when the carbon material was used as the negative electrode are shown in Table 2.

In the diffraction pattern measured by the wide-angle X-ray diffraction method of the present invention, the average interplanar spacing d of the (002) plane calculated using the Bragg equation is 3.4. Above, 3.9 Hereinafter, the size Lc of the crystallizer in the c-axis direction is 8 Above, 50 The peak of the diffraction pattern below, and having a surface spacing d of 3.25 in the above peaks Above, 3.45 In Examples 3 and 4 of the peak of the (002) plane of the graphite structure, the charge capacity and the discharge capacity were high, and the charge and discharge efficiency was also high.

In Comparative Example 4 which does not have an amorphous halo pattern according to an amorphous structure, although the efficiency is high, both the charge capacity and the discharge capacity are low values. Further, in the wide-angle X-ray diffraction method of the synchronized emission light of the present invention, Comparative Example 5 which belongs only to the amorphous halo pattern of the amorphous structure but does not have the (002) plane peak of the graphite structure, although charging The capacity and discharge capacity are high, but the efficiency is low.

In addition, when the wide-angle X-ray diffraction using the conventional laboratory specification device is used, the interplanar spacing d in the embodiment is not detected to be 3.25. Above, 3.45 The peak of the (002) plane of the graphite structure below.

Further, the Raman spectra of Examples 3 and 4 and Comparative Example 5 which are based on the amorphous structure are not greatly different, and the presence of the characteristics of the material of the present invention cannot be specified by Raman spectroscopy. A crystalline structure derived from graphite in amorphous carbon.

(industrial availability)

A carbon material capable of providing a lithium ion battery having a high charging capacity and a high discharge capacity can be provided.

10. . . Secondary battery

12. . . Negative electrode

14. . . Negative current collector

13. . . negative electrode

20. . . Positive electrode

twenty two. . . Positive current collector

twenty one. . . positive electrode

16. . . Electrolyte

18. . . Isolator

Fig. 1 is a diffraction pattern obtained by the simultaneous emission of light of Example 1.

2 is a schematic view of a lithium ion secondary battery.

12. . . Negative electrode

14. . . Negative current collector

13. . . negative electrode

20. . . Positive electrode

twenty two. . . Positive current collector

twenty one. . . positive electrode

16. . . Electrolyte

18. . . Isolator

Claims (9)

A carbon material for a lithium ion secondary battery having an average interplanar spacing d of 3.00 obtained by a wide-angle X-ray diffraction method according to the following conditions (A) to (E) is 3.40 Above and 3.90 Hereinafter, the size Lc of the crystallizer in the c-axis direction is 8 Above and 50 The following amorphous structure has a (002) plane spacing d of 3.25 Above and less than 3.40 Graphite structure; (A) Light source: Synchrotron radiation (B) Large Debye-Scherrer camera, camera radius: 286.48 mm (C) Beam size: vertical 0.3 mm × horizontal 3.0 mm (D) Detector: image plate (50μm = 0.01°) (E) incident X-ray: wavelength 1.0 (12.4keV). A carbon material for a lithium ion secondary battery is a diffraction pattern measured by a wide-angle X-ray diffraction method according to the following conditions (A) to (E), and has an average surface of a (002) plane calculated by a Bragg equation. The interval d is 3.4 Above and 3.9 Hereinafter, the size Lc of the crystallizer in the c-axis direction is 8 Above and 50 The peak of the diffraction pattern below, and the above-mentioned peak has a surface spacing d of 3.25 Above and 3.45 The following peaks of the (002) plane of the graphite structure; (A) Light source: Synchrotron radiation (B) Large Debye-Scheller camera, camera radius: 286.48 mm (C) Beam size: Vertical 0.3 mm × Horizontal 3.0 mm (D) Detector: image plate (50 μm = 0.01 °) (E) incident X-ray: wavelength 1.0 (12.4keV). The carbon material for a lithium ion secondary battery according to the first or second aspect of the invention, wherein the specific surface area obtained by the BET three-point method of nitrogen adsorption is 15 m ² /g or less and 1 m ² /g or more. The carbon material for a lithium ion secondary battery according to any one of claims 1 to 3, which contains 95% by weight or more of carbon atoms and contains 0.5% by weight or more and 5% by weight or less of nitrogen atoms as carbon atoms. Elements. A negative electrode material for a lithium ion secondary battery, which comprises the carbon material for a lithium ion secondary battery according to any one of claims 1 to 4. A lithium ion secondary battery comprising the negative electrode material for a lithium ion secondary battery of claim 5 of the patent application. A method for producing a negative electrode material for a lithium ion secondary battery, comprising 100 parts by weight of a carbon material for a lithium ion secondary battery according to claim 1 or 2, 1 to 30 parts by weight of a binder, and a solvent 10 for viscosity adjustment. ~400 parts by weight of kneading, a step of obtaining a mixture as a slurry or a paste is obtained. The method for producing a negative electrode material for a lithium ion secondary battery according to claim 7, wherein the mixture further contains an additive. A method for producing a negative electrode for a lithium ion secondary battery, comprising: a step of molding a mixture produced by the production method of claim 7 of the patent application, and collecting the obtained molded body and the negative electrode to obtain a negative electrode; Or a step of applying the above mixture as a negative electrode material to a negative electrode current collector to obtain a negative electrode.