WO2013042223A1 - Carbon material for lithium ion secondary batteries, negative electrode material for lithium ion secondary batteries, and lithium ion secondary battery - Google Patents

Abstract

This carbon material for lithium ion secondary batteries has an amorphous structure wherein the average interplanar spacing (d) of the (002) plane as determined by wide-angle X-ray diffraction is from 3.40 Å to 3.90 Å (inclusive) and the crystallite size (Lc) in the c-axis direction is from 8 Å to 50 Å (inclusive) and a graphite structure wherein the interplanar spacing (d) of the (002) plane is 3.25 Å or more but 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 has been used for the negative electrode of a lithium ion secondary battery. This is because even if the charge / discharge cycle proceeds, dendritic lithium is hardly deposited on the negative electrode using the carbon material, and safety is guaranteed.
Such a carbon material includes a highly crystalline material such as graphite and an amorphous carbon material called hard carbon. A material with high crystallinity such as graphite has advantages that the irreversible capacity is small and the charge / discharge efficiency is high, but there is a limit to the charge capacity and the discharge capacity, and there is a problem that it is difficult to increase the capacity. On the other hand, although the amorphous carbon material has a high charge capacity and discharge capacity, there is a problem that the irreversible capacity is large and the charge / discharge efficiency is low. For this reason, materials having both crystalline and amorphous properties have been studied so far. The charge / discharge capacity refers to the respective electric capacities when charging and discharging are performed for the first time after the battery is created, and the charge / discharge efficiency refers to the efficiency expressed by the discharge capacity / charge capacity.
For example, in Patent Document 1, the interplanar spacing is evaluated by a diffraction peak measured using a general-purpose wide-angle X-ray diffractometer, and furthermore, a laminated structure of carbon hexagonal mesh planes (that is, crystal parts) in a carbon material by a Raman spectrum. And the technique which evaluated the ratio of an amorphous carbon component etc. is disclosed. However, in the technique disclosed in Patent Document 1, the crystal structure of graphite contained in an amorphous material cannot be found by wide-angle X-ray diffraction, and the high charge capacity, discharge capacity, and excellent charge / discharge efficiency of the present invention are not found. The technology for coexisting amorphous / crystalline is not disclosed.

JP 2006-236752 A

The present invention can solve the above-mentioned problems, and according to the present invention, a lithium ion battery having a high charge capacity and discharge capacity and excellent balance of charge capacity, discharge capacity and charge / discharge efficiency is provided. 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.

The above object is achieved by the following items (1) to (6).

(1) Under the following conditions (A) to (E), the average interplanar spacing d of the (002) plane obtained by the wide-angle X-ray diffraction method is 3.40 mm or more and 3.90 mm or less, and the c-axis direction Lithium ions having an amorphous structure with a crystallite size Lc of 8 to 50 mm and a graphite structure with a (002) plane spacing d of 3.25 to 3.40 mm. Carbon material for secondary batteries.
(A) Light source: Synchrotron radiation (B) Large Debye-Scherrer camera, camera radius: 286.48 mm
(C) Beam size: Length 0.3mm x width 3.0mm
(D) Detector: Imaging plate (50 μm = 0.01 °)
(E) Incident X-ray: wavelength of 1.0 mm (12.4 keV)

(2) A diffraction pattern measured by a wide-angle X-ray diffraction method under the following conditions (A) to (E) is calculated using the Bragg equation. The (002) plane average plane distance d is 3.4 mm. The peak of the diffraction pattern in which the crystallite size Lc in the c-axis direction is not less than 8 and not more than 50 and not more than 3.9 and has an interplanar spacing d of 3.25 to 3 A carbon material for a lithium ion secondary battery having a (002) plane peak with a graphite structure of .45% or less.
(A) Light source: Synchrotron radiation (B) Large Debye-Scherrer camera, camera radius: 286.48 mm
(C) Beam size: Length 0.3mm x width 3.0mm
(D) Detector: Imaging plate (50 μm = 0.01 °)
(E) Incident X-ray: wavelength of 1.0 mm (12.4 keV)

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

(4) In the carbon material for a lithium ion secondary battery according to any one of (1) to (3) above,
A carbon material for a lithium ion secondary battery containing 95 wt% or more of carbon atoms and containing 0.5 wt% or more and 5 wt% or less of nitrogen atoms as elements other than carbon atoms.

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

(6) A lithium ion secondary battery including the negative electrode material for a lithium ion secondary battery according to (5) above.
(7) Kneading 100 parts by weight of the carbon material for a lithium ion secondary battery according to (1) or (2), 1 to 30 parts by weight of a binder, and 10 to 400 parts by weight of a viscosity adjusting solvent, Including obtaining a slurry or paste mixture,
A method for producing a negative electrode material for a lithium ion secondary battery.
(8) The method for producing a negative electrode material for a lithium ion secondary battery according to (7), wherein the mixture further contains an additive.
(9) A step of molding the mixture produced by the production method of (7) above and laminating the obtained molded body with a negative electrode current collector to obtain a negative electrode, or a negative electrode current collector using the mixture as a negative electrode material The manufacturing method of the negative electrode for lithium ion secondary batteries including the process of apply | coating to and obtaining a negative electrode.

According to the present invention, a carbon material for a lithium ion secondary battery, a negative electrode material for a lithium ion secondary battery, and lithium capable of providing a lithium ion battery having high charge / discharge efficiency and high charge capacity and discharge capacity. An ion secondary battery is provided.

2 is a diffraction pattern of synchrotron radiation in Example 1. FIG. It is a schematic diagram of a lithium ion secondary battery.

Hereinafter, although the preferable example of this invention is demonstrated, this invention is not limited to these examples. Additions, omissions, substitutions, and other modifications can be made without departing from the spirit of the present invention.
Embodiment 1 of the present invention will be described below with reference to the drawings.
(Carbon material for lithium ion secondary battery)
First, the outline | summary of the carbon material for lithium ion secondary batteries of this invention (henceforth a carbon material may be demonstrated).
The carbon material for a lithium ion secondary battery of the present invention is
Under the following conditions (A) to (E), the average interplanar spacing d of the (002) plane obtained by the wide angle X-ray diffraction method is 3.40 mm or more and 3.90 mm or less, and the crystallites in the c-axis direction For a lithium ion secondary battery having an amorphous structure with a size Lc of 8 to 50 mm and a graphite structure with a (002) plane spacing d of 3.25 to 3.40 mm Carbon material.
(A) Light source: Synchrotron radiation (B) Large Debye-Scherrer camera, camera radius: 286.48 mm
(C) Beam size: Length 0.3mm x width 3.0mm
(D) Detector: Imaging plate (50 μm = 0.01 °)
(E) Incident X-ray: wavelength of 1.0 mm (12.4 keV)

Next, the carbon material for a lithium ion secondary battery will be described in detail.
The raw materials or precursors used for the carbon material for lithium ion secondary batteries are not particularly limited, but the petroleum-based tars and pitches produced as a by-product during ethylene production, coal tars produced during coal dry distillation, and low coal tars are low. Heavy components obtained by distilling off boiling components and pitches, petroleum-based or coal-based tars or pitches such as tars and pitches obtained by liquefaction of coal, and those obtained by crosslinking the tars, pitches, etc., and thermosetting A resin obtained by carbonizing a resin or a resin composition such as an adhesive resin or a thermoplastic resin is preferable, and a resin or a resin composition described below is particularly preferable. However, tar, pitch obtained from the above-mentioned petroleum, coal, etc., or those subjected to a crosslinking treatment thereof are also included in the broadly defined resin or resin composition in the present invention, and these may be used alone or in combination of two or more. Can do.
Further, as will be described later, the resin composition contains the above resin as a main component and can contain a curing agent, an additive and the like.

Here, the thermosetting resin is not particularly limited. For example, a phenol resin such as a novolac type phenol resin or a resol type phenol resin, an epoxy resin such as a bisphenol type epoxy resin or a novolac type epoxy resin, a melamine resin, a urea resin, or aniline. Examples thereof include resins, cyanate resins, furan resins, ketone resins, unsaturated polyester resins, and urethane resins. In addition, modified products obtained by modifying these with various components can also be used.

The thermoplastic resin is not particularly limited. For example, polyethylene, polystyrene, polyacrylonitrile, acrylonitrile-styrene (AS) resin, acrylonitrile-butadiene-styrene (ABS) resin, polypropylene, vinyl chloride, methacrylic resin, polyethylene terephthalate, Polyamide, polycarbonate, polyacetal, polyphenylene ether, polybutylene terephthalate, polyphenylene sulfide, polysulfone, polyethersulfone, polyetheretherketone, polyetherimide, polyamideimide, polyimide, polyphthalamide, and the like can be given.

A thermosetting resin is preferable as the resin as the main component used in the carbon material of the present invention. Thereby, the remaining carbon rate of a carbon material can be raised more.
Among thermosetting resins, it is preferably selected from novolac type phenol resins, resol type phenol resins, melamine resins, furan resins, aniline resins, and modified products thereof. Thereby, the freedom degree of design of a carbon material spreads and it can manufacture at low cost.

Moreover, when using a thermosetting resin, the hardening | curing agent can be used together.
Although it does not specifically limit as a hardening | curing agent used here, For example, in the case of a novolak-type phenol resin, a hexamethylene tetramine, a resol type phenol resin, a polyacetal, paraform etc. can be used. In the case of epoxy resins, known as epoxy resins such as polyamine compounds such as aliphatic polyamines and aromatic polyamines, acid anhydrides, imidazole compounds, dicyandiamide, novolac-type phenol resins, bisphenol-type phenol resins, and resol-type phenol resins. Can be used.
Even if it is a thermosetting resin that usually uses a predetermined amount of a curing agent, the resin composition used in the present invention may use a smaller amount than usual or may be used without using a curing agent. You can also.

Moreover, in the resin composition used by this invention, an additive can be mix | blended besides this.
The additive used here is not particularly limited. For example, a carbon material precursor carbonized at 200 to 800 ° C., an organic acid, an inorganic acid, a nitrogen-containing compound, an oxygen-containing compound, an aromatic compound, and a non-ferrous metal A metal element etc. can be mentioned.
The above additives may be used alone or in combination of two or more depending on the type and properties of the resin used.

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

Here, the following can be illustrated as nitrogen-containing resin.
Examples of thermosetting resins include melamine resins, urea resins, aniline resins, cyanate resins, urethane resins, phenol resins modified with nitrogen-containing components such as amines, and epoxy resins.
Examples of the thermoplastic resin include polyacrylonitrile, acrylonitrile-styrene (AS) resin, acrylonitrile-butadiene-styrene (ABS) resin, polyamide, polyetherimide, polyamideimide, polyimide, polyphthalamide, and the like.

Moreover, the following can be illustrated as resin other than nitrogen-containing resin.
Examples of the thermosetting resin include phenol resin, epoxy resin, furan resin, and unsaturated polyester resin.

Examples of the thermoplastic resin include polyethylene, polystyrene, polypropylene, vinyl chloride, methacrylic resin, polyethylene terephthalate, polycarbonate, polyacetal, polyphenylene ether, polybutylene terephthalate, polyphenylene sulfide, polysulfone, polyethersulfone, and polyetheretherketone. .

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. For example, hexamethylenetetramine, which is a curing agent for a novolac type phenol resin, and aliphatic polyamine, which is a curing agent for an epoxy resin. In addition to the aromatic polyamine, dicyandiamide and the like, besides the curing agent component, a compound containing nitrogen such as an amine compound, ammonium salt, nitrate, nitro compound which does not function as a curing agent can be used.
As the nitrogen-containing compound, one type may be used or two or more types may be used in combination, whether or not the main component resin contains nitrogen-containing resins.

The resin composition used for 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 performing such a carbonization treatment of the resin composition or resin, the carbon atom content in the carbon material finally obtained is 95 wt% or more, and the nitrogen atom content is 0.5 to 5 wt%. Is preferred. The carbon atom content is more preferably 96 wt% or more.
Thus, by containing 0.5 wt% or more, particularly 1.0 wt% or more of nitrogen atoms, it is possible to impart electrical characteristics suitable for the carbon material due to the electronegativity of nitrogen. Thereby, occlusion and discharge | release of lithium ion can be accelerated | stimulated and a high charging / discharging characteristic can be provided.

Further, by setting the nitrogen atom to 5 wt% or less, particularly 3 wt% or less, the electrical characteristics imparted to the carbon material are suppressed from becoming excessively strong, and the occluded lithium ions are electrically connected to the nitrogen atoms. Adsorption is prevented. Thereby, an increase in irreversible capacity can be suppressed and high charge / discharge characteristics can be obtained.

The nitrogen content in the carbon material of the present invention is not limited to the nitrogen content in the resin composition or the resin, but is subjected to a condition for carbonizing the resin composition or the resin, or a curing treatment or a pre-carbonization treatment before the carbonization treatment. In some cases, these conditions can also be adjusted by appropriately setting.
For example, as a method of obtaining the carbon material having the nitrogen content as described above, the nitrogen content in the resin composition or the resin is set as a predetermined value, and conditions for carbonizing the resin composition, particularly the final temperature are adjusted. There are methods.

The method for preparing the resin composition used for the carbon material of the present invention is not particularly limited. For example, the above main component resin and other components are blended in a predetermined ratio, and these are melt mixed. These components can be prepared by dissolving them in a solvent and mixing them, or by pulverizing and mixing these components.

In the carbon material, the nitrogen content was measured by a thermal conductivity method.
In this method, a measurement sample is converted into a simple gas (CO ₂ , H ₂ O, and N ₂ ) using a combustion method, and then the gasified sample is homogenized and then passed through a column. Thereby, these gas is isolate | separated in steps and content of carbon, hydrogen, and nitrogen can be measured from each thermal conductivity.
In this invention, it implemented using the Perkin-Elmer company-made elemental-analysis measuring apparatus "PE2400".

Further, as shown in FIG. 1, the carbon material of the present invention is obtained by a wide angle X-ray diffraction method under the following conditions (A) to (E) (a diffraction pattern measured by a wide angle X-ray diffraction method is (Calculated using the Bragg equation) (002) The average interplanar spacing d is 3.40 mm or more and 3.90 mm or less, and the crystallite size Lc in the c-axis direction is 8 mm or more and 50 mm or less. Lithium ions having a crystalline structure (peak of diffraction pattern) and a graphite structure (peak of (002) plane) having a (002) plane spacing d of 3.25 mm or more and less than 3.40 mm. It is a carbon material for secondary batteries.
(A) Light source: Synchrotron radiation (B) Large Debye-Scherrer camera, camera radius: 286.48 mm
(C) Beam size: Length 0.3mm x width 3.0mm
(D) Detector: Imaging plate (50 μm = 0.01 °)
(E) Incident X-ray: wavelength of 1.0 mm (12.4 keV)
The surface spacing d of the (002) plane is derived from the diffraction angle (spectral reflection angle) θ by a parabolic approximation method, that is, a parabola passing through any number of points near the peak top by the least square method, and the peak is peaked. It decides by the method of making it the top, and calculates using the following Bragg formula.
λ = 2d _hkl sinθ Bragg equation (d _hkl = d ₀₀₂ )
λ: incident X-ray wavelength θ: reflection angle of spectrum The carbon material of the present invention has an average interplanar spacing d of (002) plane of 3.40 mm or more and 3.90 mm or less, and the crystallite size in the c-axis direction It has an amorphous structure in which Lc is not less than 8% and not more than 50%, and also has a graphite structure in which the (002) plane spacing d is not less than 3.25 and less than 3.40%. Since it is a material, it has an amorphous structure with an average interplanar spacing that allows lithium to easily enter and exit, so that charge capacity and discharge capacity can be increased. The average interplanar spacing d of the (002) plane in the amorphous structure is more preferably 3.45 mm or more and less than 3.85 mm. Furthermore, since the amorphous structure has a graphite structure, lithium ions can be smoothly occluded / desorbed, so that charge / discharge efficiency can be increased while having a high charge capacity and discharge capacity.
The wide-angle X-ray diffraction method is well known as a technique for analyzing the structure of carbon materials. However, in the present invention, the wide-angle X-ray diffraction method using synchrotron radiation by SPring-8 of the High Brightness Optical Science Research Center is extremely By using a measurement method having high resolution, it was possible to identify a graphite structure present in amorphous carbon, which was not known conventionally. Based on this technology, the present inventors have been able to reach the development of a material that can achieve high charge capacity and high discharge capacity, which is the main feature of the present invention.

Further, the carbon material of the present invention may have an average interplanar spacing d of the (002) plane of 3.40 mm or more and 3.90 mm or less, and particularly when it is 3.60 mm or more, occlusion of lithium ions. It is preferable that the shrinkage / expansion between the layers is less likely to occur, and the decrease in charge / discharge cycleability can be further suppressed.
On the other hand, when the average interplanar spacing d of the (002) plane is 3.80 mm or less, it is preferable because occlusion / desorption of lithium ions is performed smoothly and a decrease in charge / discharge efficiency can be further suppressed.
Furthermore, in the carbon material of the present invention, the crystallite size Lc in the c-axis direction (the (002) plane orthogonal direction) is preferably 8 to 50 mm.
By setting Lc to 8% or more, particularly 9% or more, there is an effect that a space between carbon layers capable of inserting and extracting lithium ions is formed, and a sufficient charge / discharge capacity can be obtained. In addition, by setting it to 50 mm or less, particularly 15 mm or less, it is possible to suppress the collapse of the carbon laminate structure due to occlusion / desorption of lithium ions and the reductive decomposition of the electrolytic solution, and to suppress the decrease in charge / discharge efficiency and charge / discharge cycleability. effective.
Lc is calculated as follows.
It was determined using the following Scherrer equation from the half-value width of the (002) plane peak of the amorphous structure and the diffraction angle (spectral reflection angle) of the amorphous structure obtained from the wide-angle X-ray diffraction measurement.
Lc = 0.94λ / (βcosθ) (Scherrer equation)
Lc: crystallite size λ: incident X-ray wavelength β: half width of peak (radian)
θ: Reflection angle of spectrum

Furthermore, the carbon material of the present invention preferably has a specific surface area of 15 m ² / g or less and 1 m ² / g or more according to the BET three-point method in nitrogen adsorption. More preferably, the specific surface area according to the BET three-point method in nitrogen adsorption is 10 m ² / g or less and 1 m ² / g or more.
Reaction with a carbon material and electrolyte solution can be suppressed because the specific surface area by BET 3 point method in nitrogen adsorption is 15 m < ² > / g or less.
Moreover, there exists an effect that appropriate permeability to the carbon material of electrolyte solution is acquired by making the specific surface area by BET 3 point method in nitrogen adsorption into 1 m < ² > / g or more.
The calculation method of the specific surface area is as follows.
The monomolecular adsorption amount Wm was calculated from the following formula (1), the total surface area Total was calculated from the following formula (2), and the specific surface area S was calculated from the following formula (3).
1 / [W (Po / P-1) = (C-1) / WmC (P / Po) / WmC (1)
In the formula (1), P: pressure of the adsorbate gas in the adsorption equilibrium, Po: saturated vapor pressure of the adsorbate at the adsorption temperature, W: adsorption amount at the adsorption equilibrium pressure P, Wm: monomolecular layer adsorption amount, C : Constant on the magnitude of interaction between solid surface and adsorbate (C = exp {(E1-E2) RT}) [E1: heat of adsorption of first layer (kJ / mol), E2: measurement temperature of adsorbate Liquefaction heat (kJ / mol)]
Total = (WmNAcs) M (2)
In formula (2), N: Avogadro number, M: molecular weight, Acs: adsorption cross section S = Total / w (3)
In formula (3), w: sample weight (g)

The carbon material as described above can be manufactured as follows.
First, a resin or resin composition to be carbonized is manufactured.
The apparatus for preparing the resin composition is not particularly limited. For example, when melt mixing is performed, a kneading apparatus such as a kneading roll, a single screw or a twin screw kneader can be used. Moreover, when performing melt | dissolution mixing, mixing apparatuses, such as a Henschel mixer and a disperser, can be used. When performing pulverization and mixing, for example, an apparatus such as a hammer mill or a jet mill can be used.
The resin composition thus obtained may be one obtained by physically mixing a plurality of types of components, or is applied during mixing (stirring, kneading, etc.) during preparation of the resin composition. A part of the material may be chemically reacted with mechanical energy and thermal energy converted from the mechanical energy. Specifically, a mechanochemical reaction using mechanical energy or a chemical reaction using thermal energy may be performed.

The carbon material of the present invention is obtained by carbonizing the above resin composition or resin. Carbonization 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. For example, the carbonization treatment can be performed at a temperature of 1 to 200 ° C./hour and a temperature increase of 0.1 to 50 hours, preferably 0.5 to 10 hours. The atmosphere during the carbonization treatment is an inert atmosphere such as nitrogen or helium gas, or a substantially inert atmosphere where a trace amount of oxygen is present in the inert gas, or a reducing gas atmosphere. Is preferred. By doing in this way, thermal decomposition (oxidative decomposition) of resin can be suppressed and a desired carbon material can be obtained.
Conditions such as temperature and time during the carbonization can be adjusted as appropriate in order to optimize the characteristics of the carbon material.

Prior to performing the carbonization treatment, a pre-carbonization treatment can be performed. The pre-carbonization treatment refers to a process in which a heat treatment is performed at a temperature lower than that of the carbonization treatment to make the resin infusible.
Here, the conditions for the pre-carbonization treatment are not particularly limited. For example, the pre-carbonization treatment can be performed at 200 to 600 ° C. for 1 to 10 hours. Thus, even if the resin composition or the resin is infusibilized by performing the pre-carbonization treatment before the carbonization treatment, and the resin composition or the resin is pulverized before the carbonization treatment step, the resin composition after the pulverization is performed. It is possible to prevent a product or resin from being re-fused during carbonization, and to efficiently obtain a desired carbon material.
At this time, the amorphous structure in which the average face spacing d of the (002) plane of the present invention is 3.40 mm or more and 3.90 mm or less and the crystallite size Lc in the c-axis direction is 8 mm or more and 50 mm or less. As an example of a method for obtaining a carbon material for a lithium ion secondary battery having a graphite structure having a (002) plane spacing d of 3.25 mm or more and less than 3.40 mm, a reducing gas, The pre-carbonization treatment can be performed in the absence of an inert gas.

Further, when a thermosetting resin or a polymerizable polymer compound is used as the resin constituting the carbon material, the resin composition or the resin can be cured before the pre-carbonization treatment.
Although it does not specifically limit as a hardening processing method, For example, it can carry out by the method of giving the heat quantity which can perform a hardening reaction to a resin composition, the method of thermosetting, or the method of using resin and a hardening | curing agent together. Thereby, since the pre-carbonization treatment can be performed substantially in the solid phase, the carbonization treatment or the pre-carbonization treatment can be performed in a state in which the resin structure is maintained to some extent, and the structure and characteristics of the carbon material can be controlled. become.

In the case of performing the carbonization treatment or the pre-carbonization treatment, metals, pigments, lubricants, antistatic agents, antioxidants, and the like can be added to the resin composition to impart desired properties to the carbon material. .

When the said hardening process and / or pre carbonization process are performed, you may grind | pulverize a processed material after the said carbonization process after that. In such a case, variation in the thermal history during the carbonization treatment can be reduced, and the uniformity of the surface state of the carbon material can be improved. And the handleability of a processed material can be made favorable.
Furthermore, the present invention has an amorphous structure in which the average spacing d of (002) planes is 3.40 mm or more and 3.90 mm or less and the crystallite size Lc in the c-axis direction is 8 mm or more and 50 mm or less. In order to obtain a carbon material for a lithium ion secondary battery having a graphite structure having a (002) plane spacing d of 3.25 mm or more and less than 3.40 mm, in the presence of a reducing gas or an inert gas Then, it is naturally cooled (cooled) to 800 to 500 ° C., and then cooled to 200 ° C. or lower, preferably 100 ° C. or lower, at 20 ° C./hour or more and 500 ° C./hour or less.
If cooling is performed under conditions within the above range, the cooling rate is faster than that of natural cooling, and a unique structure that appropriately includes a graphite structure in an amorphous structure can be obtained, whereby the carbon material of the present invention can be obtained. Guessed.

(Lithium secondary battery)
Next, an embodiment of a negative electrode material for a secondary battery (hereinafter simply referred to as “negative electrode material”) of the present invention and a lithium secondary battery (hereinafter simply referred to as “secondary battery”) which is an embodiment using the same. explain.

FIG. 2 is a schematic diagram showing the configuration of the embodiment of the 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 electrolyte solution 16, and a separator 18. Including.

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

The negative electrode material of the present invention is manufactured, for example, as follows.
1 to 30 parts by weight of a binder (fluorine polymer including polyethylene, polypropylene, etc., acrylic resin, polyimide, or rubbery polymer such as butyl rubber or butadiene rubber) with respect to 100 parts by weight of the carbon material, A viscosity adjusting solvent (N-methyl-2-pyrrolidone, dimethylformamide, water, etc.) 10 to 400 parts by weight and an appropriate amount of additives (dispersant, conductive material, etc.) were added and kneaded to form a paste. The negative electrode material 12 can be obtained by molding the mixture into a sheet shape, a pellet shape, or the like by compression molding, roll molding, or the like.
By laminating with the negative electrode current collector 14, the negative electrode 13 can be manufactured.

Also, 1 to 30 parts by weight of a binder (fluorine polymer including polyethylene, polypropylene, etc., rubbery polymer such as acrylic resin, polyimide, butyl rubber, butadiene rubber, etc.) with respect to 100 parts by weight of the carbon material, A suitable amount of a viscosity adjusting solvent (N-methyl-2-pyrrolidone, dimethylformamide, water, etc.) was added and kneaded, and the resulting slurry was used as the negative electrode material 12, and this was used as the negative electrode current collector 14. The negative electrode 13 can also be produced by coating or molding.

As the electrolytic solution 16, a solution obtained by dissolving a lithium salt serving as an electrolyte in a non-aqueous solvent is used.
As this non-aqueous solvent, a mixture of cyclic esters such as propylene carbonate, ethylene carbonate and γ-butyrolactone, chain esters such as dimethyl carbonate and diethyl carbonate, chain ethers such as dimethoxyethane, and the like can be used. it can.
As the electrolyte, lithium metal salts such as LiClO ₄ and LiPF ₆ , tetraalkylammonium salts, and the like can be used. Further, the above salts can be mixed with polyethylene oxide, polyacrylonitrile, etc. and used as a solid electrolyte.

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

In the cathode 21, and is not particularly limited as cathode material 20, such as lithium cobalt oxide (LiCoO _2), lithium nickel oxide (LiNiO _2), composite oxides such as lithium manganese oxide (LiMn ₂ O _4), Conductive polymers such as polyaniline and polypyrrole can be used.
As the positive electrode current collector 22, for example, an aluminum foil can be used.
The positive electrode 21 in the present embodiment can be manufactured by a known positive electrode manufacturing method.

The present invention is not limited to the above-described embodiment, but includes modifications and improvements as long as the object of the present invention can be achieved.

Next, Embodiment 2 of the present invention will be described with reference to the drawings. Regarding the second embodiment of the present invention, the points not described are the same as in the first embodiment.
(Carbon material for lithium ion secondary battery)
First, the outline | summary of the carbon material for lithium ion secondary batteries of this invention (henceforth a carbon material may be demonstrated).
The carbon material for a lithium ion secondary battery of the present invention is
A diffraction pattern measured by the wide-angle X-ray diffraction method under the following conditions (A) to (E) is calculated by using the Bragg equation, and the average spacing d of (002) planes is 3.4 mm or more, 3 .9 Å or less, having a diffraction pattern peak in which the crystallite size Lc in the c-axis direction is 8 Å or more and 50 Å or less, and the interplanar spacing d is 3.25 Å or more and 3.45 Å or less in the peak. This is a carbon material for a lithium ion secondary battery having a (002) plane peak of a graphite structure.
(A) Light source: Synchrotron radiation (B) Large Debye-Scherrer camera, camera radius: 286.48 mm
(C) Beam size: Length 0.3mm x width 3.0mm
(D) Detector: Imaging plate (50 μm = 0.01 °)
(E) Incident X-ray: wavelength of 1.0 mm (12.4 keV)

In the carbon material of the present invention, as shown in FIG. 1, the diffraction pattern measured by the wide-angle X-ray diffraction method under the following conditions (A) to (E) is calculated using the Bragg equation. The (002) plane has an average interplanar spacing d of 3.4 mm or more and 3.9 mm or less, a crystallite size Lc in the c-axis direction of 8 mm or more and 50 mm or less, and a peak of the diffraction pattern, This is a carbon material for a lithium ion secondary battery having a (002) plane peak with a graphite structure in which the interplanar spacing d is not less than 3.25 and not more than 3.45.
(A) Light source: Synchrotron radiation (B) Large Debye-Scherrer camera, camera radius: 286.48 mm
(C) Beam size: Length 0.3mm x width 3.0mm
(D) Detector: Imaging plate (50 μm = 0.01 °)
(E) Incident X-ray: wavelength of 1.0 mm (12.4 keV)
The carbon material of the present invention has an average interplanar spacing d of 3.4 to 3.9 mm and a crystal structure size Lc in the c-axis direction of 8 to 50 and diffraction based on an amorphous structure. Lithium is a material having a pattern peak and having a (002) plane peak of a graphite structure in which the interplanar spacing d is 3.25 to 3.45 mm. Since it has an amorphous structure with an average plane spacing of a size that allows easy entry and exit, the charge capacity and discharge capacity can be increased. The surface spacing d of the (002) plane in the amorphous structure is more preferably 3.45 mm or more and 3.85 mm or less. Furthermore, since the amorphous structure has a graphite structure, lithium ions can be smoothly occluded / desorbed, so that charge / discharge efficiency can be increased while having a high charge capacity and discharge capacity.
Wide-angle X-ray diffraction is well known as a technique for analyzing the structure of carbon materials. In wide-angle X-ray diffraction using synchrotron radiation in the present invention, a measurement method with extremely high resolution is used. It was possible to identify a graphite structure present in amorphous carbon, which was not known in the past. Based on this technology, the present inventors have been able to reach the development of a material that can achieve high charge capacity and high discharge capacity, which is the main feature of the present invention.
In the wide-angle X-ray diffraction method of the present invention, synchrotron radiation is used. As the electron energy, a radiation facility (apparatus) capable of obtaining 1 GeV or more, more preferably 7 GeV or more can be used. Examples of such facilities (equipment) include the PF of the High Energy Accelerator Research Organization in Japan, SPring-8 of the High Brightness Optical Science Research Center, the APS of Argonne National Laboratory in the United States, the USRLS in the European Union (EU), etc. In particular, SPring-8, APS, and USRLS are preferable.

The carbon material of the present invention may have an average interplanar spacing d of the (002) plane of 3.4 mm or more and 3.9 mm or less, but particularly when it is 3.6 mm or more, occlusion of lithium ions. It is preferable that the shrinkage / expansion between the layers is less likely to occur, and the decrease in charge / discharge cycleability can be further suppressed.
On the other hand, when the average interplanar spacing d of the (002) plane is 3.8 mm or less, it is preferable because lithium ions can be smoothly occluded and desorbed, and a decrease in charge / discharge efficiency can be further suppressed.
Furthermore, in the carbon material of the present invention, the crystallite size Lc in the c-axis direction (the (002) plane orthogonal direction) is preferably 8 to 50 mm.
By setting Lc to 8% or more, particularly 9% or more, there is an effect that a space between carbon layers capable of inserting and extracting lithium ions is formed, and a sufficient charge / discharge capacity can be obtained. In addition, by setting it to 50 mm or less, particularly 15 mm or less, it is possible to suppress the collapse of the carbon laminate structure due to occlusion / desorption of lithium ions and the reductive decomposition of the electrolytic solution, and to suppress the decrease in charge / discharge efficiency and charge / discharge cycleability. effective.
Lc is calculated as follows.
It was determined using the following Scherrer equation from the half-value width and diffraction angle of the (002) plane peak of the amorphous structure in the spectrum obtained from wide-angle X-ray diffraction measurement.
Lc = 0.94λ / (βcosθ) (Scherrer equation)
Lc: crystallite size λ: incident X-ray wavelength β: half width of peak (radian)
θ: Reflection angle of spectrum

The carbon material of the present invention is obtained by carbonizing the above resin composition or resin.
The conditions for the carbonization treatment are not particularly limited. For example, the temperature is raised from room temperature at 1 to 200 ° C./hour, and kept at 800 to 3000 ° C. for 0.1 to 50 hours, preferably 0.5 to 10 hours. Can be done. The atmosphere during the carbonization treatment is an inert atmosphere such as nitrogen or helium gas, or a substantially inert atmosphere where a trace amount of oxygen is present in the inert gas, or a reducing gas atmosphere. Is preferred. By doing in this way, thermal decomposition (oxidative decomposition) of resin can be suppressed and a desired carbon material can be obtained.
Conditions such as temperature and time during the carbonization can be adjusted as appropriate in order to optimize the characteristics of the carbon material.

Prior to performing the carbonization treatment, a pre-carbonization treatment can be performed.
Here, the conditions for the pre-carbonization treatment are not particularly limited. For example, the pre-carbonization treatment can be performed at 200 to 600 ° C. for 1 to 10 hours. Thus, even if the resin composition or the resin is infusibilized by performing the pre-carbonization treatment before the carbonization treatment, and the resin composition or the resin is pulverized before the carbonization treatment step, the resin composition after the pulverization is performed. It is possible to prevent the object or resin from being re-fused during the carbonization treatment, and to obtain a desired carbon material efficiently.
At this time, the average spacing d of (002) planes calculated using the Bragg equation is 3.4 mm or more and 3.9 mm or less, and the crystallite size Lc in the c-axis direction is 8 mm or more and 50 mm or less. A carbon material for a lithium ion secondary battery having a peak of the (002) plane of a graphite structure having a peak of the diffraction pattern and having an interplanar spacing d of 3.25 to 3.45 mm in the peak is obtained. An example of a method for this is to perform pre-carbonization in the absence of a reducing gas or an inert gas.

When the said hardening process and / or pre carbonization process are performed, you may grind | pulverize a processed material after the said carbonization process after that. In such a case, variation in the thermal history during the carbonization treatment can be reduced, and the uniformity of the surface state of the carbon material can be improved. And the handleability of a processed material can be made favorable.
Furthermore, the average plane distance d of (002) planes calculated using the Bragg equation is 3.4 mm or more and 3.9 mm or less, and the crystallite size Lc in the c-axis direction is 8 mm or more and 50 mm or less. To obtain a carbon material for a lithium ion secondary battery having a diffraction pattern peak and having a (002) plane peak of a graphite structure in which the interplanar spacing d is 3.25 to 3.45 mm. In addition, the conditions may be appropriately selected according to the raw material to be used. For example, after carbonization, if necessary, it is naturally cooled to 800 to 500 ° C. in the presence of a reducing gas or an inert gas, and then 100 You may cool at 100 degrees C / hour until it becomes below ° C.
By doing so, it is presumed that the cooling rate is in an appropriate state, a unique structure appropriately including a graphite structure is formed in the amorphous structure, and the carbon material of the present invention can be obtained.
However, in the present invention, a diffraction pattern measured by a wide-angle X-ray diffraction method is calculated using the Bragg equation without using graphite or graphitization catalyst as a raw material or precursor to be used. There is a diffraction pattern peak in which the distance d is 3.4 mm or more and 3.9 mm or less, the crystallite size Lc in the c-axis direction is 8 mm or more and 50 mm or less, and the interplanar distance d is in the peak. It is characterized in that a carbon material for a lithium ion secondary battery having a (002) plane peak with a graphite structure of 3.25 to 3.45 mm is obtained. There may be no problem if graphite or the like is used as an additive as needed, after appropriately selecting a raw material or a precursor, a process, or the like that expresses this characteristic, and having an embodiment in which the present invention can be carried out.

Hereinafter, the present invention will be described with reference to examples. However, the present invention is not limited to the examples. In the examples and comparative examples, “parts” represents “parts by weight” and “%” represents “% by weight”.
First, measurement methods in the following examples and comparative examples will be described.

(1. Measurement of (002) plane spacing d by synchrotron radiation and measurement of crystallite size Lc in the c-axis direction)
Wide-angle X-ray diffraction under the following conditions (A) to (E) at the Large Synchrotron Radiation Research Center (JASRI) Synchrotron Radiation Facility SPring-8, BL19B2 The surface spacing d (002) and the crystallite size (Lc) in the c-axis direction were evaluated. The diffraction angle (spectral reflection angle) θ is determined by a parabolic approximation method, that is, a method in which a parabola passing through any number of points near the peak top of the spectrum is derived by the least square method, and the peak is the peak top. .
(A) Light source: Synchrotron radiation (B) Large Debye-Scherrer camera, camera radius: 286.48 mm
(C) Beam size: Length 0.3mm x width 3.0mm
(D) Detector: Imaging plate (50 μm = 0.01 °)
(E) Incident X-ray: wavelength of 1.0 mm (12.4 keV)
○ (002) plane spacing d
λ = 2d _hkl sinθ Bragg equation (d _hkl = d ₀₀₂ )
λ: incident X-ray wavelength θ: spectral reflection angle ○ crystallite size Lc in the c-axis direction
It was determined from the half width of the (002) plane peak of the amorphous structure and the diffraction angle (spectral reflection angle) θ of the amorphous structure obtained from the wide-angle X-ray diffraction measurement using the following Scherrer equation.
Lc = 0.94λ / (βcos θ) (Scherrer equation)
Lc: crystallite size λ: incident X-ray wavelength β: half-width of peak (radian)
θ: Reflection angle of spectrum

(2. Measurement of the average spacing d of (002) planes using a conventional lab-scale X-ray diffractometer)
Using a Shimadzu X-ray diffractometer “XRD-7000” (incident X-ray wavelength CuKα1.54 mm), the (002) plane spacing d was measured.

(3. Measurement of Raman spectrum)
Using an InViaReflex Raman microscope manufactured by RENISHAW, magnifying the sample with a 20x objective lens, irradiating the sample with a YAG laser beam having a wavelength of 532 nm and 2.5 mW, measuring Raman scattering light 5 times, and measuring range 100 to 2000 cm ⁻¹ , measured at an exposure time of 100 seconds. Pull the one baseline to the obtained spectrum intensity IG of G band from the base line in the range of the intensity ID and 1560 ~ 1650 cm ^-1 of D band in the range of 1300 ~ 1400 cm ^-1 of the Raman spectrum The R value (ID / IG), which is the intensity ratio, was determined.

(4. Specific surface area)
Measurement was performed by the BET three-point method in nitrogen adsorption using a Nova-1200 device manufactured by Yuasa. A specific calculation method is as described in the above embodiment.

(5. Carbon content, nitrogen content)
The measurement was performed using an elemental analysis measuring device “PE2400” manufactured by PerkinElmer. The measurement sample is converted into CO ₂ , H ₂ O, and N ₂ using a combustion method, and then the gasified sample is homogenized and then passed through the column. Thereby, these gases were separated stepwise, and the contents of carbon, hydrogen, and nitrogen were measured from the respective thermal conductivities.
A) Carbon content rate After carbonizing the obtained carbon material in 110 degreeC / vacuum for 3 hours, the carbon composition ratio was measured using the elemental analysis measuring device.
B) Nitrogen content The obtained carbon material was dried at 110 ° C./vacuum for 3 hours, and then the nitrogen composition ratio was measured using an elemental analyzer.

(6. Charge capacity, discharge capacity, charge / discharge efficiency)
(1) Manufacture of a bipolar coin cell for secondary battery evaluation 10 parts of polyvinylidene fluoride as a binder and N-methyl-2-as a diluting solvent with respect to 100 parts of the carbon material obtained in each example and comparative example A suitable amount of pyrrolidone was added and mixed to prepare a slurry-like negative electrode mixture. The prepared negative electrode slurry-like mixture was applied to both sides of 18 μm copper foil, and then vacuum-dried at 110 ° C. for 1 hour. After vacuum drying, the electrode was pressure-formed by a roll press. This was cut out as a circle having a diameter of 16.156 mm to produce a negative electrode.
The positive electrode was evaluated with a bipolar coin cell using lithium metal. As the electrolytic solution, a solution obtained by dissolving 1 mol / liter of lithium perchlorate in a mixed solution of ethylene carbonate and diethyl carbonate having a volume ratio of 1: 1 was used.

(2) Evaluation of Charging Capacity and Discharging Capacity The charging condition was that charging was stopped at a constant current of 25 mA / g until it reached 1 mV, and then the charging was terminated when the current attenuated to 1.25 mA / g with 1 mV holding. The cut-off potential under discharge conditions was 1.5V.

(3) Evaluation of charge / discharge efficiency Based on the value obtained in the above (2), the charge / discharge efficiency was calculated by the following formula.
Charge / discharge efficiency (%) = [discharge capacity / charge capacity] × 100

Example 1
As a resin composition, phenol resin PR-217 (manufactured by Sumitomo Bakelite Co., Ltd.) was treated in the order of the following steps (a) to (f) to obtain a carbon material.
(A) Temperature reduction from room temperature to 500 ° C. at 100 ° C./hour without any of reducing gas replacement, inert gas replacement, reducing gas flow and inert gas flow (b) Reducing gas replacement and inert gas replacement Then, after degreasing treatment at 500 ° C. for 2 hours without cooling gas flow and inert gas flow, cooling (c) fine pulverization with a vibrating ball mill (d) from room temperature to 1200 under substitution and flow of inert gas (nitrogen) (E) Carbonization for 8 hours at 1200 ° C. under an inert gas (nitrogen) flow (f) After natural cooling to 600 ° C. under an inert gas (nitrogen) flow, 600 ℃ to 100 ℃, cooling at 100 ℃ / hour

(Example 2)
In Example 1, an aniline resin (synthesized by the following method) was used instead of the phenol resin.
100 parts of aniline, 697 parts of 37% aqueous formaldehyde, and 2 parts of oxalic acid were placed in a three-necked flask equipped with a stirrer and a condenser, reacted at 100 ° C. for 3 hours, and dehydrated to obtain 110 parts of 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 the aniline resin and 10 parts of hexamethylenetetramine obtained as described above was treated in the same process as in Example 1 to obtain a carbon material.

(Comparative Example 1)
A carbon material composed of graphite (mesophase carbon microbeads) was prepared.

(Comparative Example 2)
In Example 1, instead of phenol resin, in place of coal tar pitch (manufactured by JFE Shoji Co., Ltd.), the steps of (d), (e), and (f) were changed as follows. The carbon material was obtained by performing the same process.
(D) Inert gas (nitrogen) replacement and flow, from room temperature to 1100 ° C., heated at 100 ° C./hour (e) Inactive gas (nitrogen) flow, 1100 ° C. for 4 hours carbonization (f) No Natural cooling to 100 ° C under active gas (nitrogen) flow

(Comparative Example 3)
In Example 1, the process of (d), (e), (f) was changed as follows, and it processed in the process similar to Example 1, and obtained the carbon material.
(D) Inactive gas (nitrogen) substitution and flow from room temperature to 1000 ° C. at 100 ° C./hour (e) Carbonization treatment at 1000 ° C. for 8 hours under inert gas (nitrogen) flow (f) Natural cooling to 100 ° C under active gas (nitrogen) flow

Table 1 shows the evaluation results of the carbon materials obtained in the above Examples and Comparative Examples, and the measurement results of the charge capacity, discharge capacity, and charge / discharge efficiency when the carbon material is used as a negative electrode.

It has an amorphous structure in which the average interplanar spacing d of the (002) plane of the present invention is 3.40 mm or more and 3.90 mm or less, and the crystallite size Lc in the c-axis direction is 8 mm or more and 50 mm or less. In addition, in Examples 1 and 2 which are carbon materials for lithium ion secondary batteries having a graphite structure in which the (002) plane spacing d is 3.25 mm or more and less than 3.40 mm, both the charge capacity and the discharge capacity are High charge and discharge efficiency.
In Comparative Example 1 having no amorphous halo pattern based on the amorphous structure, the efficiency was high, but both the charge capacity and the discharge capacity were low. Further, in the comparative example 2 which has only the amorphous halo pattern based on the amorphous structure and does not have the (002) plane peak of the graphite structure in the wide-angle X-ray diffraction method using synchrotron radiation of the present invention, the charge capacity and discharge capacity are high. The efficiency is lowered, and in Comparative Example 3, the discharge capacity and the efficiency are lower than in the example.
Further, in wide-angle X-ray diffraction using a conventional lab scale apparatus, the interplanar spacing d of the graphite structure that is 3.25 mm or more and less than 3.40 mm in the example was not detected.
Further, the Raman spectra of Examples 1 and 2 and Comparative Examples 2 and 3 based on an amorphous structure are all results that are not significantly different. In the Raman spectrum, amorphous carbon, which is a feature of the material of the present invention, is obtained. It was not possible to identify the crystal structure derived from graphite.

(Example 3)
As a resin composition, phenol resin PR-217 (manufactured by Sumitomo Bakelite Co., Ltd.) was treated in the order of the following steps (a) to (f) to obtain a carbon material.
(A) Temperature reduction from room temperature to 500 ° C. at 100 ° C./hour without any of reducing gas replacement, inert gas replacement, reducing gas flow and inert gas flow (b) Reducing gas replacement and inert gas replacement Then, after degreasing treatment at 500 ° C. for 2 hours without cooling gas flow and inert gas flow, cooling (c) fine pulverization with a vibrating ball mill (d) from room temperature to 1200 under substitution and flow of inert gas (nitrogen) (E) Carbonization for 8 hours at 1200 ° C. under an inert gas (nitrogen) flow (f) After natural cooling to 600 ° C. under an inert gas (nitrogen) flow, 600 Cooling from 100 ° C to 100 ° C or less at 100 ° C / hour

(Example 4)
In Example 3, an aniline resin (synthesized by the following method) was used instead of the phenol resin.
100 parts of aniline, 697 parts of 37% aqueous formaldehyde, and 2 parts of oxalic acid were placed in a three-necked flask equipped with a stirrer and a condenser, reacted at 100 ° C. for 3 hours, and dehydrated to obtain 110 parts of 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 the aniline resin and 10 parts of hexamethylenetetramine obtained as described above was treated in the same process as in Example 3 to obtain a carbon material.

(Comparative Example 4)
A carbon material composed of graphite (mesophase carbon microbeads) was prepared.

(Comparative Example 5)
In Example 3, instead of phenol resin, instead of coal tar pitch (manufactured by JFE Shoji Co., Ltd.), the steps of (d), (e), and (f) were changed as in Example 1 as described below. The carbon material was obtained by performing the same process.
(D) Inert gas (nitrogen) replacement and flow, from room temperature to 1100 ° C., heated at 100 ° C./hour (e) Inactive gas (nitrogen) flow, 1100 ° C. for 4 hours carbonization (f) No Natural cooling to 100 ° C or lower under active gas (nitrogen) flow

Table 2 shows the evaluation results of the carbon materials obtained in the above Examples and Comparative Examples and the measurement results of the charge capacity, discharge capacity, and charge / discharge efficiency when the carbon material is used as a negative electrode.

In the diffraction pattern measured by the wide-angle X-ray diffraction method of the present invention, the average spacing d of (002) planes calculated using the Bragg equation is 3.4 mm or more and 3.9 mm or less, and the crystal in the c-axis direction A (002) plane peak of a graphite structure having a diffraction pattern peak with a child size Lc of 8 to 50 mm and a face spacing d of 3.25 to 3.45 mm in the peak. In Examples 3 and 4 having the above, both the charge capacity and discharge capacity were high, and the charge / discharge efficiency was also high.
In Comparative Example 4 having no amorphous halo pattern based on the amorphous structure, the efficiency was high, but both the charge capacity and the discharge capacity were low. Further, in Comparative Example 5 having only the amorphous halo pattern based on the amorphous structure and not having the (002) plane peak of the graphite structure in the wide-angle X-ray diffraction method using synchrotron radiation of the present invention, the charge capacity and discharge capacity are high. Efficiency became low.
In addition, in wide-angle X-ray diffraction using a conventional lab-scale apparatus, a peak on the (002) plane of the graphite structure in which the interplanar spacing d in the example was 3.25 mm or more and 3.45 mm or less was not detected.
Further, the Raman spectra of Examples 3 and 4 and Comparative Example 5 based on the amorphous structure are all the same results. In the Raman spectrum, the amorphous carbon, which is a feature of the material of the present invention, is not observed. The existing crystal structure derived from graphite could not be specified.

It is possible to provide a carbon material that can provide a lithium ion battery having a high charge capacity and discharge capacity.

DESCRIPTION OF SYMBOLS 10 Secondary battery 12 Negative electrode material 14 Negative electrode collector 13 Negative electrode 20 Positive electrode material 22 Positive electrode collector 21 Positive electrode 16 Electrolytic solution 18 Separator

Claims (9)

1. Under the following conditions (A) to (E), the average interplanar spacing d of the (002) plane obtained by the wide angle X-ray diffraction method is 3.40 mm or more and 3.90 mm or less, and the crystallites in the c-axis direction For a lithium ion secondary battery having an amorphous structure with a size Lc of 8 to 50 mm and a graphite structure with a (002) plane spacing d of 3.25 to 3.40 mm Carbon material.
   (A) Light source: Synchrotron radiation (B) Large Debye-Scherrer camera, camera radius: 286.48 mm
   (C) Beam size: Length 0.3mm x width 3.0mm
   (D) Detector: Imaging plate (50 μm = 0.01 °)
   (E) Incident X-ray: wavelength of 1.0 mm (12.4 keV)
2. A diffraction pattern measured by the wide-angle X-ray diffraction method under the following conditions (A) to (E) is calculated by using the Bragg equation, and the average spacing d of (002) planes is 3.4 mm or more, 3 .9 Å or less, having a diffraction pattern peak in which the crystallite size Lc in the c-axis direction is 8 Å or more and 50 Å or less, and the interplanar spacing d is 3.25 Å or more and 3.45 Å or less in the peak. A carbon material for a lithium ion secondary battery having a (002) plane peak of a graphite structure.
   (A) Light source: Synchrotron radiation (B) Large Debye-Scherrer camera, camera radius: 286.48 mm
   (C) Beam size: Length 0.3mm x width 3.0mm
   (D) Detector: Imaging plate (50 μm = 0.01 °)
   (E) Incident X-ray: wavelength of 1.0 mm (12.4 keV)
3. The carbon material for a lithium ion secondary battery according to claim 1 or 2,
   A carbon material for a lithium ion secondary battery having a specific surface area of 15 m ² / g or less and 1 m ² / g or more by a BET three-point method in nitrogen adsorption.
4. The carbon material for a lithium ion secondary battery according to any one of claims 1 to 3,
   A carbon material for a lithium ion secondary battery containing 95 wt% or more of carbon atoms and containing 0.5 wt% or more and 5 wt% or less of nitrogen atoms as elements other than carbon atoms.
5. A negative electrode material for a lithium ion secondary battery comprising the carbon material for a lithium ion secondary battery according to any one of claims 1 to 4.
6. A lithium ion secondary battery comprising the negative electrode material for a lithium ion secondary battery according to claim 5.
7. 100 parts by weight of the carbon material for a lithium ion secondary battery according to claim 1 or 2; 1 to 30 parts by weight of a binder; and 10 to 400 parts by weight of a viscosity adjusting solvent are kneaded to form a slurry or paste. Obtaining a prepared mixture,
   A method for producing a negative electrode material for a lithium ion secondary battery.
8. 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.
9. A step of forming a mixture produced by the production method of claim 7 and laminating the obtained molded body with a negative electrode current collector to obtain a negative electrode, or applying the mixture as a negative electrode material to a negative electrode current collector The manufacturing method of the negative electrode for lithium ion secondary batteries including the process of obtaining a negative electrode.

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