JP2016186912A - Composite carbon material for nonaqueous secondary battery, and nonaqueous secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: a carbon material with which a nonaqueous secondary battery having high capacity and excellent low-temperature input/output characteristics and cycle characteristics can be obtained; and a high performance nonaqueous secondary battery using the carbon material.SOLUTION: A composite carbon material for a nonaqueous secondary battery is a composite carbon material containing a carbonaceous material (B) on a surface of a carbon material (A) that is capable of absorbing and desorbing lithium ions. The average of microscopic Raman R values and the standard deviation (σ) of 30 composite carbon materials selected at random are 0.1-0.85 and 0.1 or less, respectively. The composite carbon material has a tap density of 0.6-1.20 g/cmand a specific surface area of 1-30 m/g.SELECTED DRAWING: None

Description

  The present invention relates to a non-aqueous secondary battery including a non-aqueous secondary battery composite carbon material and a non-aqueous secondary battery negative electrode using the non-aqueous secondary battery composite carbon material.

  In recent years, demand for high-capacity secondary batteries has increased with the downsizing of electronic devices. In particular, lithium ion secondary batteries having higher energy density and excellent large current charge / discharge characteristics have attracted attention as compared to nickel / cadmium batteries and nickel / hydrogen batteries. Conventionally, high capacity of lithium ion secondary batteries has been widely studied, but in recent years, the demand for higher performance of lithium ion secondary batteries has been increasing. Therefore, there is a demand to achieve a long life.

  For lithium ion secondary batteries, it is known to use a carbon material such as graphite as the negative electrode active material. Among them, graphite having a high degree of graphitization, when used as an active material for a negative electrode for a lithium ion secondary battery, has a capacity close to 372 mAh / g, which is the theoretical capacity for lithium occlusion of graphite. Since it is excellent also in the property, it is known that it is preferable as an active material for negative electrodes. On the other hand, when the active material layer containing the negative electrode material is densified to increase the capacity, the destruction / deformation of the material increases the irreversible capacity of charge / discharge during the initial cycle, decreases the large current charge / discharge characteristics, There was a problem of decline.

In order to solve the above problem, for example, in Patent Document 1, spheroidized natural graphite is produced by subjecting scaly natural graphite to mechanical energy treatment, and spheroidized natural graphite is used as nuclear graphite on its surface. A technique for improving fillability and high-speed charge / discharge characteristics by coating amorphous carbon is disclosed.
Patent Document 2 discloses a multi-layer structure carbon material obtained by adhering an organic carbide to the surface of a graphitic carbonaceous material, and the amount of the organic carbide is 12 weight as a residual carbon amount with respect to 100 parts by weight of the graphitic carbonaceous material. Non-aqueous solvent secondary battery with high discharge capacity, low charge-discharge irreversible capacity during the initial cycle, and high safety with respect to the electrolyte by adjusting to 0.1 parts by weight or less Is disclosed. Patent Document 3 discloses a composite carbon material having a low crystalline carbon material on the surface of highly crystalline carbonaceous particles, and has a tap density of 0.43 to 0.69 g / cm ³ and a micro Raman R value of 0.2 or more. It is disclosed that a non-aqueous solvent secondary battery excellent in low temperature characteristics can be obtained by setting the ratio of 20% or more.

In Patent Document 4, composite particles of graphite particles and carbon fine particles having a primary particle diameter of 3 nm or more and 500 nm or less, the ratio of the value of 90% to the value of 10% (R ₍ It is disclosed that a non-aqueous solvent secondary battery having excellent input / output characteristics at low temperatures can be obtained by setting the _90/10) value) to 1 or more and 4.3 or less.

JP 2000-340232 A JP 09-213328 A International Publication No. 11/145178 JP 2014-060148 A

  However, according to the study by the present inventors, the composite graphite in which the graphite surface disclosed in Patent Documents 1 and 2 is coated with amorphous carbon is in comparison with the flaky graphite or spheroidized graphite particles used as a raw material. Although high capacity and good rapid charge / discharge characteristics can be obtained, the amorphous carbon coating uniformity is not taken into account, so those characteristics are still insufficient. The composite carbon material disclosed in Patent Document 3 has an exposed portion of highly crystalline carbonaceous particles having a micro Raman R value of 0.2 or less by setting the ratio of the micro Raman R value of 0.2 or more to 20% or more. Is considered, but the distribution and variation of micro-Raman values, especially the micro-Raman value distribution and variation in particles with high micro-Raman R values, that is, the uneven distribution of low-crystalline carbon material coating sites are considered. And their properties were still inadequate. Further, although it is considered that the composite particles disclosed in Patent Document 4 do not include particles with extremely large and small microscopic Raman R values, the distribution and variation of microscopic Raman R values are also considered. And their properties were still inadequate.

  The present invention has been made in view of such background art, and its object is to provide a carbon material capable of obtaining a non-aqueous secondary battery having high capacity and excellent input / output characteristics and cycle characteristics. As a result, it is to provide a high-performance non-aqueous secondary battery.

As a result of intensive studies to solve the above problems, the inventors of the present invention have a carbon material (A) capable of occluding and releasing lithium ions (hereinafter also referred to as “carbon material (A)”). A composite carbon material (hereinafter also referred to as “composite carbon material”) containing a carbonaceous material (B) on the surface, and the average value of microscopic Raman R values of 30 randomly selected composite carbon materials is 0. .1 to 0.85 and a standard deviation (σ _R ) of 0.1 or less provides a non-aqueous secondary battery negative electrode material having high capacity and excellent low-temperature input / output characteristics and cycle characteristics. As a result, the present invention has been completed.

The reason why the composite carbon material according to the present invention has the above effect is considered as follows.
That is, the average value of the microscopic Raman R values of 30 composite carbon materials randomly selected from the composite carbon materials is 0.1 or more and 0.85 or less, and the standard deviation (σ _R ) is 0.1 or less. This means that the surface of the carbon material (A) uniformly contains a low crystalline carbonaceous material in which Li ions are easy to insert and desorb, and Li ions are easy to insert and desorb the carbon material (A). It is possible to suppress an excessive current from flowing only in a specific portion, and to perform Li ion insertion and desorption uniformly and smoothly even at low temperatures and during large current charge / discharge. Therefore, it is considered that high capacity and excellent low-temperature input / output characteristics and cycle characteristics can be obtained.

That is, the gist of the present invention is a composite carbon material containing a carbonaceous material (B) on the surface of a carbon material (A) capable of inserting and extracting lithium ions, and 30 randomly selected composite carbon materials. A composite carbon material for a non-aqueous secondary battery (C) characterized in that the average value of the microscopic Raman R value of the material is 0.1 or more and 0.85 or less and the standard deviation (σ _R ) is 0.1 or less. )
In addition, the other gist includes a positive electrode and a negative electrode capable of inserting and extracting lithium ions, and an electrolyte, and the negative electrode includes a current collector and a negative electrode active material layer formed on the current collector. The non-aqueous secondary battery, wherein the negative electrode active material layer contains the composite carbon material.

  The composite carbon material of the present invention provides a non-aqueous secondary battery having high capacity, good low-temperature input / output characteristics, and cycle characteristics by using it as a negative electrode active material for non-aqueous secondary batteries. Can do.

Hereinafter, the contents of the present invention will be described in detail. The description of the invention constituent elements described below is an example (representative example) of an embodiment of the present invention, and the present invention is not limited to these forms unless it exceeds the gist.
The composite carbon material for a non-aqueous secondary battery of the present invention is a composite carbon material containing a carbonaceous material (B) on the surface of a carbon material (A) capable of occluding and releasing lithium ions. The 30 selected composite carbon materials have an average value of microscopic Raman R values of 0.1 to 0.85 and a standard deviation (σ _R ) of 0.1 or less.

<Composite carbon material for non-aqueous secondary batteries>
The composite carbon material of the present invention contains a carbonaceous material (B) on the surface of a carbon material (A) capable of occluding and releasing lithium ions, and microscopic Raman of 30 composite carbon materials selected at random. There is no particular limitation as long as the average R value is 0.1 or more and 0.85 or less and the standard deviation (σ _R ) is 0.1 or less. For example, graphite, amorphous carbon, carbonaceous material having a low graphitization degree It is preferable that the carbon material (A) made of the above is coated with a carbonaceous material (B) such as amorphous carbon or graphitized material.
Here, the term “covered” refers to an embodiment in which at least a part or the entire surface of the carbon material (A) is coated or attached with the carbonaceous material (B).

<Physical properties of composite carbon material for non-aqueous secondary battery>
・ Average value of standard Raman R value, standard deviation (σ _R )
The average value and standard deviation (σ _R ) of the micro Raman R values of 30 randomly selected composite carbon materials in the composite carbon material of the present invention are values measured by a measurement method described later.

The average value of the micro Raman R value is 0.1 or more and 0.85 or less, preferably 0.15 or more, more preferably 0.2 or more, still more preferably 0.23 or more, and particularly preferably 0.25 or more. Preferably, it is 0.8 or less, more preferably 0.65 or less, still more preferably 0.5 or less, and particularly preferably 0.4 or less.
The standard deviation is 0.1 or less, preferably 0.085 or less, more preferably 0.08 or less, still more preferably 0.07 or less, particularly preferably 0.06 or less, usually 0.001 or more, preferably 0. 0.01 or more, more preferably 0.02 or more.

When the average value and the standard deviation (σ _R ) of the microscopic Raman R value are out of the above range, it indicates that the carbonaceous material (A) surface is not uniformly coated with a carbonaceous material in which Li ions are easily inserted and desorbed, Especially at low temperatures and during high-speed charge / discharge, for example, Li ions covered with a large amount of carbonaceous material flow excessively only to specific sites where Li ions are likely to be inserted and desorbed. It becomes difficult to insert and desorb, and low-temperature input / output characteristics and cycle characteristics tend to deteriorate.

The Raman R value is a value measured by Raman microscopic measurement under the following conditions using a Raman spectroscope (Nicolet Almega XR manufactured by Thermo Fisher Scientific, etc.).
Microscopic Raman measurement is performed with the particles to be measured naturally dropped on the sample stage and the surface flattened.
Excitation wavelength: 532 nm
Laser power on sample: 1 mW or less Resolution: 10 cm ⁻¹
Irradiation diameter: 1μmΦ
Measurement range: 400 cm ^{−1 to} 4000 cm ⁻¹
Peak intensity measurement: Linear baseline correction in a range of about ^{1100cm -1 ~1750cm} -1.

Method for calculating Raman R value: 1 in the spectrum after linear baseline correction
Calculating a peak intensity _{I A} to peak top of a peak _{P A} around 580 cm ^-1, read the peak intensity _{I B} to peak top of a peak _{P B} in the vicinity of 1360 cm ^-1, R value _(I B / _{I A)} To do. An average value and a standard deviation (σ _R ) are calculated from 30 randomly selected particles to be measured.

· In the composite carbon material of microscopic Raman _{R 15} values present invention, the Raman _{R 15} value represented by the following formula (1), 25% usually less, preferably 15% or less, more preferably 12% or less, more preferably Is 9% or less, particularly preferably 5% or less, and is usually larger than 0%. If it is in the said range, the carbonaceous material (B) can be coat | covered uniformly on the surface of a carbon material (A), and it has shown that there is little exposure of a carbon material (A) surface. For this reason, it becomes possible to insert and desorb Li ions uniformly and smoothly, and a composite carbon material having excellent low-temperature output characteristics and cycle characteristics can be obtained.
Microscopic Raman R ₍₁₅₎ value (%) = number of composite carbon materials that are 0.15 or less of microscopic Raman R values of 30 randomly selected composite carbon materials / 30 × 100 (1)

-Volume-based average particle size (average particle size d50)
The composite carbon material of the present invention has a volume-based average particle size (also referred to as “average particle size d50”) of preferably 1 μm or more, more preferably 5 μm or more, and still more preferably 8 μm or more. The average particle diameter d50 is usually 50 μm or less, preferably 40 μm or less, more preferably 35 μm or less, still more preferably 30 μm or less, and particularly preferably 25 μm or less. If the average particle size d50 is too small, the non-aqueous secondary battery obtained by using the composite carbon material tends to increase the irreversible capacity and the loss of the initial battery capacity, while if the average particle size d50 is too large, the slurry There are cases where inconveniences such as streaking in coating occur, deterioration of high current density charge / discharge characteristics, and deterioration of low temperature input / output characteristics.

  In this specification, the average particle size d50 is obtained by adding 10 mL of a 0.2 mass% aqueous solution of polyoxyethylene sorbitan monolaurate (for example, Tween 20 (registered trademark)) as a surfactant to a carbon material. 0.01 g was suspended, and this was introduced as a measurement sample into a commercially available laser diffraction / scattering particle size distribution measurement device (for example, LA-920 manufactured by HORIBA), and the measurement sample was irradiated with 28 kHz ultrasonic waves at an output of 60 W for 1 minute. After that, the volume is defined as a volume-based median diameter measured by the measuring device.

・ BET specific surface area (SA)
The specific surface area (SA) measured by the BET method of the composite carbon material of the present invention is usually 1 m ² / g or more, preferably 2 m ² / g or more, more preferably 3 m ² / g or more, and further preferably 4 m ² / g. As mentioned above, it is particularly preferably 5 m ² / g or more, most preferably 6 m ² / g or more. Further, it is preferably 30 m ² / g or less, more preferably 20 m ² / g or less, still more preferably 15 m ² / g or less, and particularly preferably 12 m ² / g or less.

When the specific surface area is within the above range, it is possible to sufficiently secure the portion where Li enters and exits, so the high speed charge / discharge characteristics output characteristics are excellent, and the activity of the active material against the electrolytic solution can be moderately suppressed. However, the high-capacity battery tends to be manufactured.
In addition, when a negative electrode is formed using a composite carbon material, an increase in reactivity with the electrolytic solution can be suppressed and gas generation can be suppressed, so that a preferable non-aqueous secondary battery can be provided. .

The BET specific surface area was measured using a surface area meter (for example, a specific surface area measuring device “Gemini 2360” manufactured by Shimadzu Corp.), preliminarily dried at 100 ° C. for 3 hours in a nitrogen stream on a carbon material sample, and then liquid nitrogen. It is defined as a value measured by a nitrogen adsorption BET 6-point method using a gas flow method using a nitrogen-helium mixed gas that is cooled to a temperature and adjusted accurately so that the relative pressure value of nitrogen with respect to atmospheric pressure is 0.3.

-Tap density The tap density of the composite carbon material of the present invention is usually 0.6 g / cm ³ or more, preferably 0.70 g / cm ³ or more, more preferably 0.75 g / cm ³ or more, and further preferably 0.90 g / cm. cm ³ or more, particularly preferably 0.95 g / cm ³ or more, usually 1.5 g / cm ³ or less, preferably 1.3 g / cm ³ or less, more preferably 1.2 g / cm ³ or less. More preferably, it is 1.1 g / cm ³ or less.

When the tap density is within the above range, the processability such as streaking during the production of the electrode plate is good, and the high-speed charge / discharge characteristics are excellent. In addition, since the carbon density in the particles is difficult to increase, the rolling property is good and the high-density negative electrode sheet tends to be easily formed.
The tap density was filled into the cell by dropping the carbon material of the present invention through a sieve having a mesh size of 300 μm into a cylindrical tap cell having a diameter of 1.6 cm and a volume capacity of 20 cm ³ using a powder density measuring device. After that, a tap having a stroke length of 10 mm is performed 1000 times and defined as the density obtained from the volume at that time and the mass of the sample.

-Circularity The circularity of the composite carbon material of the present invention is 0.88 or more, preferably 0.90 or more, more preferably 0.91 or more. The circularity is preferably 1 or less, more preferably 0.98 or less, and still more preferably 0.97 or less. When the circularity is within the above range, the high current density charge / discharge characteristics of the non-aqueous secondary battery tend to be suppressed. The circularity is defined by the following formula, and when the circularity is 1, a theoretical sphere is obtained.

When the circularity is within the above range, when the circularity is within the above range, the bending degree of Li ion diffusion decreases, the electrolyte solution moves smoothly in the interparticle voids, and the carbon materials are appropriately in contact with each other. Therefore, it tends to exhibit good rapid charge / discharge characteristics and cycle characteristics.
Circularity = (perimeter of equivalent circle having the same area as the particle projection shape) / (actual circumference of particle projection shape)
As the circularity value, for example, a flow type particle image analyzer (for example, FPIA manufactured by Sysmex Industrial Co., Ltd.) is used, and about 0.2 g of a sample (carbon material) is added to polyoxyethylene (20) sorbitan as a surfactant. After dispersing in a 0.2% by weight monolaurate aqueous solution (about 50 mL) and irradiating the dispersion with an ultrasonic wave of 28 kHz for 1 minute at an output of 60 W, the detection range is specified as 0.6 to 400 μm, and the particle size is The value measured for particles in the range of 1.5-40 μm is used.

-X-ray parameter The d value (interlayer distance) of the lattice plane (002 plane) obtained by X-ray diffraction by the Gakushin method of the composite carbon material of the present invention is preferably 0.335 nm or more and less than 0.340 nm. . Here, the d value is more preferably 0.339 nm or less, and still more preferably 0.337 nm or less. When the d002 value is within the above range, the initial irreversible capacity tends to suppress an increase because the crystallinity of graphite is high. Here, 0.335 nm is a theoretical value of graphite.

  The crystallite size (Lc) of the carbon material determined by X-ray diffraction by the Gakushin method is preferably 1.5 nm or more, more preferably 3.0 nm or more. Within the above range, the crystallinity is not too low, and the reversible capacity is difficult to decrease when a non-aqueous secondary battery is obtained. The lower limit of Lc is the theoretical value of graphite.

<Method for producing composite carbon material for non-aqueous secondary battery>
The composite carbon material of the present invention is a composite carbon material containing a carbonaceous material (B) on the particle surface of the carbon material (A) capable of occluding and releasing lithium ions. The composite carbon material is not particularly limited as long as the average value of the microscopic Raman R value is 0.1 or more and 0.85 or less and the standard deviation (σ _R ) is 0.1 or less. There is a method in which the carbonaceous material (A) having the characteristics is uniformly combined with the carbonaceous material (B).

[Physical properties and production method of carbon material (A)]
(Type of carbon material)
The carbon material (A) of the present invention is a carbon material such as graphite and a carbonaceous material having a low graphitization degree, and is easily commercially available, and theoretically has a high charge / discharge capacity of 372 mAh / g. Furthermore, it is preferable that the graphite be more effective in improving the charge / discharge characteristics at a high current density than when other negative electrode active materials are used. Further, examples of graphite include natural graphite and artificial graphite, and natural graphite is more preferable from the viewpoint of good charge / discharge characteristics at a high capacity and a high current density.

Further, graphite having a small amount of impurities is preferable, and graphite having a small amount of impurities can be obtained by performing various known purification treatments.
Natural graphites are classified according to their properties into scale-like black (FlakeGraphite), scale-like (Crystal Line Graphite), massive graphite (Vein Graphite), and soil graphite (Amorphousu Graphite). (Refer to "HANDBOOKOF CARBON, GRAPHITE, DIAMOND AND FULLERENES" (published by NoyesPubLications)). The degree of graphitization is the highest at 100% for scaly graphite and massive graphite, followed by scaly graphite at 99.9%, which is suitable in the present invention.

The production area of scaly natural graphite is mainly Madagascar, China, Brazil, Ukraine, Canada, etc., and the production area of scaly graphite is mainly Sri Lanka. The main producers of soil graphite are the Korean Peninsula, China and Mexico.
Among natural graphites, for example, scaly, scaly, or massive natural graphite, highly purified scaly graphite, spheroidized natural graphite described below (hereinafter sometimes referred to as spheroidized natural graphite), and the like. It is done. Among them, it is preferable from the viewpoint of forming fine pores suitable for the inside of the carbon material and exhibiting excellent particle filling properties and charge / discharge load characteristics.

  As artificial graphite, for example, coal tar pitch, coal heavy oil, atmospheric residue, petroleum heavy oil, aromatic hydrocarbon, nitrogen-containing cyclic compound, sulfur-containing cyclic compound, polyphenylene, polyvinyl chloride, polyvinyl There are those obtained by baking organic materials such as alcohol, polyacrylonitrile, polyvinyl butyral, natural polymer, polyphenylene sulfide, polyphenylene oxide, furfuryl alcohol resin, phenol-formaldehyde resin, imide resin, and graphitized bulk mesophase. Can be mentioned.

Also, use granulated artificial graphite obtained by adding a graphitization catalyst to a graphitizable aggregate or graphite such as bulk mesophase, and a graphitizable organic substance, mixing, firing, and pulverizing. You can also.
The firing temperature can be in the range of 2500 ° C. or more and 3200 ° C. or less, and a silicon-containing compound, a boron-containing compound, or the like can be used as a graphitization catalyst during firing.

Examples of the carbonaceous material having a low degree of graphitization include those obtained by firing an organic material at a temperature of usually less than 2500 ° C., and specifically, for example, bulk mesophase and amorphous carbon. Organic substances include coal-based heavy oil such as coal tar pitch and dry distillation liquefied oil; straight-run heavy oil such as atmospheric residual oil and vacuum residual oil; ethylene tar produced as a by-product during thermal decomposition of crude oil, naphtha, etc. Heavy oils such as cracked heavy oils; aromatic hydrocarbons such as acenaphthylene, decacyclene and anthracene; nitrogen-containing cyclic compounds such as phenazine and acridine; sulfur-containing cyclic compounds such as thiophene; and aliphatic cyclics such as adamantane Compounds: Polyphenylene such as biphenyl and terphenyl, polyvinyl esters such as polyvinyl chloride, polyvinyl acetate, and polyvinyl butyral, and thermoplastic polymers such as polyvinyl alcohol.

Examples of the bulk mesophase include a carbonaceous material obtained by heat-treating petroleum heavy oil, coal heavy oil, and straight heavy oil at 400 to 600 ° C.
Examples of the amorphous carbon include particles obtained by firing a bulk mesophase and particles obtained by infusibilizing and firing a carbonaceous material precursor.
Depending on the degree of crystallinity of amorphous carbon, the firing temperature can be 600 ° C. or higher, preferably 900 ° C. or higher, more preferably 950 ° C. or higher, and usually less than 2500 ° C. , Preferably it is 2000 degrees C or less, More preferably, it is the range of 1400 degrees C or less.

At the time of firing, acids such as phosphoric acid, boric acid and hydrochloric acid, alkalis such as sodium hydroxide and the like can be mixed with the organic matter.
The carbon material (A) of the present invention may contain an oxide or other metal. Other metals include metals that can be alloyed with Li, such as Sn, Si, Al, Bi.
Furthermore, as a carbon material (A) of this invention, these can be used individually or in combination of 2 or more types.

(Physical properties of carbon material (A))
The physical properties of the carbon material (A) of the present invention are not particularly limited, but are preferably carbon materials with adjusted pore volume and pore diameter. When such a carbon material (A) is used, the carbonaceous material (B) precursor can be diffused and penetrated more uniformly on the surface of the carbon material (A) and inside the micropores, and the microscopic Raman R value of the composite carbon material. And the standard deviation (σ _R ) can be within the scope of the present invention. Below, the preferable physical property which a carbon material (A) has is illustrated.

・ Mode pore diameter (PD) in the range of 0.01μm to 1μm
The mode pore diameter (PD) in the range of 0.01 μm or more and 1 μm or less of the carbon material (A) of the present invention is a value measured using a mercury intrusion method (mercury porosimetry), and is usually 0.01 μm or more, preferably Is 0.03 μm or more, more preferably 0.05 μm or more, still more preferably 0.06 μm or more, particularly preferably 0.07 μm, usually 1 μm or less, preferably 0.65 μm or less, more preferably 0.5 μm. Hereinafter, it is more preferably 0.4 μm or less, particularly preferably 0.3 μm or less, particularly preferably 0.2 μm or less, and most preferably 0.1 μm or less.

If the mode pore diameter (PD) in the range of 0.01 μm or more and 1 μm or less is out of the above range, the electrolyte cannot efficiently spread to the voids in the particles, and the Li ion insertion / desorption sites in the particles are efficiently used. Therefore, the low temperature input / output characteristics and cycle characteristics tend to deteriorate. In addition, as described above, the carbonaceous material (B) precursor is difficult to uniformly diffuse and penetrate into the surface of the carbon material (A) and the inside of the fine pores. It becomes difficult to control the average value and standard deviation (σ _R ) of the microscopic Raman R value of the material, and the low-temperature input / output characteristics and cycle characteristics tend to deteriorate.

-Pore volume in the range of 0.01 µm or more and 1 µm or less In the carbon material (A) of the present invention, the pore volume in the range of 0.01 µm or more and 1 µm or less was measured using a mercury intrusion method (mercury porosimetry). Even if it is a pressure treatment, it is usually 0.07 mL / g or more, preferably 0.08 mL / g or more, more preferably 0.09 mL / g or more, and most preferably 0.10 mL. / G or more. Moreover, it is preferably 0.3 mL / g or less, more preferably 0.25 mL / g or less, still more preferably 0.2 mL / g or less, and particularly preferably 0.18 mL / g or less.

  When the pore volume in the range of 0.01 μm or more and 1 μm or less is less than 0.07 mL / g, the electrolyte cannot enter the particles and the Li ion insertion / desorption sites in the particles cannot be used efficiently. When charging / discharging, it becomes difficult to smoothly insert and desorb lithium ions, and the low-temperature input / output characteristics tend to be lowered. On the other hand, when it is included in the above-mentioned range, the electrolyte solution can be smoothly and efficiently distributed inside the particle, so that Li ion insertion not only in the particle outer periphery but also in the particle inside at the time of charge / discharge The desorption site can be used effectively and efficiently, and tends to exhibit good low-temperature input / output characteristics.

-Volume-based average particle size (average particle size d50)
The volume-based average particle diameter (also referred to as “average particle diameter d50”) of the carbon material (A) of the present invention is preferably 1 μm or more, more preferably 3 μm or more, still more preferably 5 μm or more, particularly preferably 8 μm or more. Preferably it is 50 micrometers or less, More preferably, it is 40 micrometers or less, More preferably, it is 30 micrometers or less, Most preferably, it is 25 micrometers or less. Within the above range, an increase in irreversible capacity can be suppressed, and there is a tendency that process properties such as line drawing in slurry application are not impaired.

-Ratio of mode pore diameter (PD) and volume-based average particle diameter (d50) in the range of 0.01 μm to 1 μm (PD / d50 (%))
The ratio (PD / d50) of the mode pore diameter (PD) in the range of 0.01 μm or more and 1 μm or less (PD / d50) of the carbon material (A) of the present invention is represented by the following formula (2). In general, it is 1.8 or less, preferably 1.80 or less, more preferably 1.00 or less, further preferably 0.90 or less, particularly preferably 0.80 or less, most preferably 0.70 or less, usually 0.01. Above, preferably 0.10 or more, more preferably 0.20 or more.
PD / d50 (%) = mode pore diameter (PD) / volume-based average particle diameter (d50) × 100 in the range of 0.01 μm or more and 1 μm or less in the pore distribution determined by the mercury intrusion method (2)
If PD / d50 is out of the above range, the electrolyte cannot efficiently spread to the voids in the particles, and the Li ion insertion / desorption sites in the particles cannot be used efficiently. Cycle characteristics tend to be reduced. In addition, the carbonaceous material (B) precursor becomes more difficult to diffuse and permeate the carbonaceous material (B) precursor more uniformly on the surface of the carbon material (A) and inside the micropores, and the average value of the micro Raman R value of the composite carbon material , And the standard deviation (σ _R ) are difficult to control, and the low-temperature input / output characteristics and cycle characteristics tend to deteriorate.

Tap density The carbon material (A) of the present invention preferably has a tap density of 0.6 g / cm ³ or more, more preferably 0.65 g / cm ³ or more, still more preferably 0.7 g / cm ³ or more, preferably 1 .3g / cm ³ or less, more preferably 1.2 g / cm ³ or less, further preferably 1.1 g / cm ³ or less.
When the tap density is within the above range, the processability such as streaking during the production of the electrode plate is good, and the high-speed charge / discharge characteristics are excellent. In addition, since the carbon density in the particles is difficult to increase, the rolling property is good and the high-density negative electrode sheet tends to be easily formed.

・ BET specific surface area (SA)
The specific surface area (SA) measured by the BET method of the carbon material (A) of the present invention is preferably 1 m ² / g or more, more preferably 2 m ² / g or more, still more preferably 3 m ² / g or more, particularly preferably. 4 m ² / g or more. Further, it is preferably 30 m ² / g or less, more preferably 20 m ² / g or less, still more preferably 17 m ² / g or less, particularly preferably 15 m ² / g or less.

If the BET specific surface area is within the above range, the portion where Li enters and exits can be secured sufficiently, so that the high-speed charge / discharge characteristic output characteristics are excellent, and the activity of the active material against the electrolytic solution can be moderately suppressed. The capacity does not increase and a high capacity battery tends to be manufactured.
In addition, when a negative electrode is formed using a carbon material (A), an increase in reactivity with the electrolytic solution can be suppressed, and gas generation can be suppressed, so that a preferable nonaqueous secondary battery is provided. Can do.

-X-ray parameter The d value (interlayer distance) of the lattice plane (002 plane) of the carbon material (A) of the present invention determined by X-ray diffraction by the Gakushin method is preferably 0.335 nm or more and less than 0.340 nm. It is. Here, the d value is more preferably 0.339 nm or less, and still more preferably 0.337 nm or less. When the d002 value is within the above range, the initial irreversible capacity tends to suppress an increase because the crystallinity of graphite is high. Here, 0.335 nm is a theoretical value of graphite.

-Circularity The circularity of the carbon material of the present invention is usually 0.88 or more, preferably 0.90 or more, more preferably 0.91 or more. The circularity is preferably 1 or less, more preferably 0.98 or less, and still more preferably 0.97 or less. When the circularity is within the above range, the high current density charge / discharge characteristics of the non-aqueous secondary battery tend to be suppressed. The circularity is defined by the following formula, and when the circularity is 1, a theoretical sphere is obtained.
When the circularity is within the above range, when the circularity is within the above range, the bending degree of Li ion diffusion decreases, the electrolyte solution moves smoothly in the interparticle voids, and the carbon materials are appropriately in contact with each other. Therefore, it tends to exhibit good rapid charge / discharge characteristics and cycle characteristics.

-Manufacturing method of carbon material (A) Although the manufacturing method of carbon material (A) which has said preferable characteristic is not specifically limited, As one of an achievement means, at least any one of an impact, compression, friction, and shear force The material carbon material is granulated by applying the mechanical energy, and the granulation step can be performed in the presence of a granulating agent that satisfies the following conditions 1) and 2).

1) Liquid at the time of granulating the raw material carbon material 2) When the granulating agent contains an organic solvent, at least one of the organic solvents has no flash point or has a flash point The flash point is 5 ° C or higher.
If it has the said granulation process, you may further have another process as needed. Another process may be carried out independently or a plurality of processes may be carried out simultaneously.
When the granulation treatment is performed by the above method, a liquid crosslinking adhesion force between the carbon material particles is generated by the granulating agent having the specified physical properties, and the carbon material particles can adhere more firmly to each other. Since the carbon material fine powder with a large amount of Li ion insertion / desorption sites adheres to the base material to be the carbon material (A) and / or has a structure encapsulated in the carbon material (A), the pores are reduced. It becomes possible to produce a carbon material (A) having many Li insertion / release sites.

In addition, physical damage to the surface of the carbon material is reduced by the granulating agent acting as a lubricant, and the carbon material being granulated by suppressing the contact between the carbon material and oxygen. Since the oxidation of the surface is also suppressed, it becomes possible to suppress the generation and increase of unstable carbon due to the collapse of the conjugated system of the molecular structure of the carbon material.
As a result, it becomes possible to produce a carbon material (A) having many particle pores and a dense particle structure.

As a more preferable embodiment of the method for producing the carbon material (A), a production method including the following first to sixth steps can be mentioned.
(1st process) The process of adjusting the particle size of raw material carbon material (2nd process) The process of mixing raw material carbon material and a granulating agent (3rd process) The process of granulating raw material carbon material (4th process) Step of removing granule (fifth step) Step of purifying granulated carbon material (sixth step) Step of increasing crystallinity of granulated carbon material Hereinafter, these steps will be described.

(1st process) The process of adjusting the particle size of raw material carbon material The raw material carbon material used by this invention is not specifically limited, Carbon materials, such as the graphite mentioned above and a carbonaceous material with a small graphitization degree, can be used. Among them, it is preferable to use natural graphite because of its high crystallinity and high capacity.
The average particle diameter (d50) of these raw material carbon materials is preferably 1 μm or more, more preferably 2 μm or more, still more preferably 3 μm or more, preferably 80 μm or less, more preferably 50 μm or less, still more preferably 35 μm or less, and very preferably Is 20 μm or less, particularly preferably 10 μm or less, and most preferably 8 μm or less.

When the average particle size is in the above range, the fine powder generated during the granulation process can be granulated while adhering to the base material that becomes the granulated carbon material or wrapping it inside the base material. A granulated carbon material having a high degree and a small amount of fine powder can be obtained.
As a method of adjusting the average particle diameter (d50) of the raw material carbon material to the above range, for example, a method of pulverizing and / or classifying the carbon material particles can be mentioned.

  There are no particular restrictions on the apparatus used for pulverization, for example, the coarse pulverizer includes a shearing mill, jaw crusher, impact crusher, cone crusher, etc., and the intermediate pulverizer includes a roll crusher, hammer mill, etc. Examples of the fine pulverizer include a mechanical pulverizer, an airflow pulverizer, and a swirl flow pulverizer. Specific examples include a ball mill, a vibration mill, a pin mill, a stirring mill, a jet mill, a cyclone mill, and a turbo mill. In particular, when obtaining graphite particles of 10 μm or less, it is preferable to use an airflow pulverizer or a swirl flow pulverizer.

  There is no particular limitation on the apparatus used for classification, but for example, in the case of dry sieving, a rotary sieving, a swaying sieving, a rotating sieving, a vibrating sieving, etc. can be used. In this case, gravity classifier, inertial classifier, centrifugal classifier (classifier, cyclone, etc.) can be used, wet sieving, mechanical wet classifier, hydraulic classifier, sedimentation classifier A centrifugal wet classifier or the like can be used.

Moreover, it is preferable that the material carbon material satisfies the following physical properties.
The ash content in the raw carbon material is preferably 1% by mass or less, more preferably 0.5% by mass or less, and still more preferably 0.1% by mass or less, based on the total mass. Moreover, it is preferable that the minimum of ash content is 1 ppm or more.
When the ash content is within the above range, when the non-aqueous secondary battery is used, it is possible to suppress deterioration of battery performance due to the reaction between the negative electrode material and the electrolytic solution during charge / discharge to a level that can be ignored. Moreover, since a great amount of time, energy, and equipment for preventing contamination are not required for manufacturing the negative electrode material, an increase in cost can be suppressed.

The aspect ratio of the raw carbon material is preferably 3 or more, more preferably 5 or more, still more preferably 10 or more, and particularly preferably 15 or more. Further, it is preferably 1000 or less, more preferably 500 or less, still more preferably 100 or less, and particularly preferably 50 or less. An aspect ratio is measured by the method of the Example mentioned later. When the aspect ratio is within the above range, it is difficult to produce large particles having a particle size of about 100 μm, while it becomes easy to obtain a strong granulated carbon material.

The surface spacing (d002) of the 002 plane and the crystallite size (Lc) of the raw carbon material by X-ray wide angle diffraction method are usually (d002) of 3.37 mm or less and (Lc) of 900 mm or more, (d0
02) is preferably 3.36 mm or less and (Lc) is preferably 950 mm or more. Surface spacing (d0
02) and the crystallite size (Lc) are values indicating the crystallinity of the negative electrode material bulk, and the smaller the value of the 002 plane spacing (d002), the greater the crystallite size (Lc). It shows that the negative electrode material has high crystallinity, and the capacity increases because the amount of lithium entering the graphite layer approaches the theoretical value. When the crystallinity is low, excellent battery characteristics (high capacity and low irreversible capacity) when high crystalline graphite is used for the electrode are not exhibited. It is particularly preferable that the above-mentioned ranges are combined for the interplanar spacing (d002) and the crystallite size (Lc).

  X-ray diffraction is measured by the following method. Carbon powder is mixed with X-ray standard high-purity silicon powder of about 15% by mass of the total amount, and the material is CuKα rays monochromatized with a graphite monochromator, and the wide angle X is measured by the reflective diffractometer method. A line diffraction curve is measured. Thereafter, the interplanar spacing (d002) and the crystallite size (Lc) are obtained using the Gakushin method.

The packing structure of the raw carbon material depends on the size, shape, and degree of interaction force between particles, but in this specification, tapping density is applied as one of the indicators for quantitative discussion of the packing structure. It is also possible to do. In the study by the present inventors, it has been confirmed that in the case of lead-like particles having a true density and an average particle size substantially equal, the tap density increases as the shape is spherical and the particle surface is smoother. In other words, in order to increase the tap density, it is important to round the shape of the particle so that it is close to a sphere, and to maintain smoothness except for the surface and chipping of the particle surface. When the particle shape approaches a spherical shape and the particle surface is smooth, the powder filling property is greatly improved. The tapping density of the raw carbon material is preferably 0.1 g / cm ³ or more, more preferably 0.2 g / cm ³ or more, and further preferably 0.3 g / cm ³ or more. The tapping density is measured by the method described later in the examples.

The argon ion laser Raman spectrum of the raw carbon material is used as an index indicating the surface properties of the particles. Raman R value is the peak intensity ratio in the vicinity of 1360 cm ^-1 to the peak intensity near 1580 cm ^-1 in the argon ion laser Raman spectrum of the raw carbon material is preferably 0.05 to 0.9, more preferably 0 .05 or more and 0.7 or less, more preferably 0.05 or more and 0.5 or less. The R value is an index representing the crystallinity in the vicinity of the surface of the carbon particle (from the particle surface to about 100 °), and the smaller the R value, the higher the crystallinity or the disordered crystal state. The Raman spectrum is measured by the method shown below. Specifically, the sample particle is naturally dropped into the Raman spectrometer measurement cell, and the sample cell is filled with the sample. While irradiating the measurement cell with an argon ion laser beam, Measure while rotating. Note that the wavelength of the argon ion laser light is 514.5 nm.

  The X-ray wide angle diffraction method of the raw material carbon material is used as an index representing the crystallinity of the whole particle, and is based on the 101 plane intensity 3R (101) based on the rhombohedral crystal structure by the X-ray wide angle diffraction method and the hexagonal crystal structure. The ratio 3R / 2H to the strength 2H (101) of the 101 surface is preferably 0.1 or more, more preferably 0.15 or more, and still more preferably 0.2 or more. The rhombohedral crystal structure is a crystal form in which a stack of graphite network structures is repeated every three layers. Moreover, the hexagonal crystal structure is a crystal form in which the stacking of the graphite network structure is repeated every two layers. In the case of scaly graphite showing a crystal form with a high ratio of rhombohedral crystal structure 3R, the acceptability of Li ions is higher than a carbon material with a low ratio of rhombohedral crystal structure 3R.

BET specific surface area of the raw carbon material is preferably ^{1 m} 2 / g or more ^{30 m} 2 / g or less, more preferably ^2m 2 / g or more ^{20 m} 2 / g or less, more preferably ^{5 m} 2 / g or more ^{15 m} 2 / g It is as follows. The specific surface area by BET method is measured by the method of the Example mentioned later. When the specific surface area of the raw material graphite is within the above range, the acceptability of Li ions becomes good, and a decrease in battery capacity due to an increase in irreversible capacity can be prevented.

(2nd process) The process which mixes a raw material carbon material and a granulating agent In order to obtain the carbon material (A) of this invention, it is preferable to granulate a raw material carbon material using a granulating agent. The granulating agent is 1) liquid during the step of granulating the raw carbon material, and 2) when the granulating agent contains an organic solvent, at least one of the organic solvents does not have a flash point, or the flash point. When it has, the flash point satisfies the condition of 5 ° C. or more.

By having a granulating agent that satisfies the above requirements, the granulating agent liquid-crosslinks between the raw material carbon materials in the subsequent step of granulating the raw material carbon material in the third step, so that the liquid between the raw material carbon materials. The attractive force generated by the capillary negative pressure in the bridge and the surface tension of the liquid acts as the liquid cross-linking adhesion force between the particles, so the liquid cross-linking adhesion force between the raw carbon materials increases and the raw carbon material adheres more firmly. It becomes possible.
In the present invention, the strength of the liquid cross-linking adhesive force between the raw material carbon materials due to the liquid crosslinking between the raw material carbon materials is proportional to the γ cos θ value (where γ: surface tension of the liquid, θ: Liquid and particle contact angle). That is, when granulating the raw material carbon material, it is preferable that the granulating agent has high wettability with the raw material carbon material. Specifically, a granulating agent satisfying cos θ> 0 so that γ cos θ value> 0 is obtained. The contact angle θ with the graphite measured by the following measuring method of the granulating agent is preferably less than 90 °.

<Measurement method of contact angle θ with carbon material>
When 1.2 μl of granulating agent is dropped on the HOPG surface, the wetting spread converges, and the contact angle θ when the shape change rate of the contact angle θ per second becomes 3% or less (also referred to as a steady state) is defined as the contact angle. It measures with a measuring apparatus (Kyowa Interface Co., Ltd. automatic contact angle meter DM-501). Here, when using a granulating agent having a viscosity at 25 ° C. of 500 cP or less, the value at 25 ° C. is used, and when using a granulating agent having a viscosity at 25 ° C. of more than 500 cP, the viscosity reaches 500 cP or less. The measured value of the contact angle θ at the heated temperature.

  Further, as the contact angle θ between the raw material carbon material and the granulating agent is closer to 0 °, the γ cos θ value increases, so that the liquid crosslinking adhesion between the carbon material particles increases, and the carbon material particles adhere more firmly. It becomes possible. Therefore, the contact angle θ of the granulating agent with the carbon material is more preferably 85 ° or less, further preferably 80 ° or less, further preferably 50 ° or less, and preferably 30 ° or less. It is particularly preferable that it is 20 ° or less.

Even when a granulating agent having a large surface tension γ is used, the γ cos θ value is increased and the adhesion of the carbon material particles is improved. Therefore, γ is preferably 0 or more, more preferably 15 or more, and even more preferably 30 or more. is there.
In addition, a viscous force acts as a resistance component against the elongation of the liquid bridge accompanying the movement of the particles, and its magnitude is proportional to the viscosity. For this reason, the viscosity of the granulating agent is not particularly limited as long as it is liquid during the granulation step of granulating the raw material graphite, but is preferably 1 cP or more during the granulation step. Further, the viscosity at 25 ° C. of the granulating agent is preferably 1 cP or more and 100,000 cP or less, more preferably 5 cP or more and 10000 cP or less, further preferably 10 cP or more and 8000 cP or less, and 50 cP or more and 6000 cP or less. Is particularly preferred. When the viscosity is within the above range, it is possible to prevent the adhered particles from being detached due to an impact force such as a collision with the rotor or casing when the raw carbon material is granulated.

  Furthermore, when the granulating agent used in the present invention contains an organic solvent, at least one of the organic solvents does not have a flash point, or when it has a flash point, the flash point is 5 ° C. or higher. . As a result, when granulating the raw material carbon material in the subsequent third step, it is possible to prevent the risk of ignition, fire, and explosion of organic compounds induced by impact and heat generation, so stable and efficient production. Can be implemented.

  Examples of the granulating agent used in the present invention include, for example, paraffinic oil such as coal tar, petroleum heavy oil, liquid paraffin, synthetic oil such as olefinic oil, naphthenic oil and aromatic oil, and vegetable oils and fats. Natural oils such as animal aliphatics, esters and higher alcohols, organic compounds such as a resin binder solution in which a resin binder is dissolved in a solvent having a flash point of 21 ° C. or higher, aqueous solvents such as water, and their A mixture etc. are mentioned. A well-known thing can be used as a resin binder. For example, cellulose-based resin binders such as ethyl cellulose, methyl cellulose, and salts thereof, acrylic resin binders such as polymethyl acrylate, polyethyl acrylate, polybutyl acrylate, polyacrylic acid, and salts thereof, polymethyl methacrylate, Methacrylic resin binders such as polyethyl methacrylate and polybutyl methacrylate, and phenol resin binders can be used. Among these, coal tar, petroleum heavy oil, paraffinic oil such as liquid paraffin, and aromatic oil are preferable because they can produce a negative electrode material having a high degree of spheroidization and a small amount of fine powder.

  As a granulating agent, it can be efficiently removed in the step of removing the granulating agent (fourth step), which will be described later, and has an adverse effect on battery characteristics such as capacity, input / output characteristics and storage / cycle characteristics. Those having no properties are preferred. Specifically, when heated to 700 ° C. in an inert atmosphere, the weight loss is usually 50% or more, preferably 80% or more, more preferably 95% or more, still more preferably 99% or more, and particularly preferably 99.9% or more. Can be selected as appropriate.

  As a method of mixing the raw material carbon material and the granulating agent, for example, a method of mixing the raw material carbon material and the granulating agent using a mixer or a kneader, or a granulating agent in which an organic compound is dissolved in a low viscosity diluent solvent, Examples include a method of removing the diluted solvent after mixing raw material graphite. In addition, when the raw material carbon material is granulated in the subsequent third step, the granulation device and the raw material carbon material are added to the granulating apparatus, and the raw material carbon material and the granulating agent are mixed and granulated. The method of performing a process simultaneously is also mentioned.

  The amount of the granulating agent added is preferably 0.1 parts by weight or more, more preferably 1 part by weight or more, still more preferably 3 parts by weight or more, still more preferably 6 parts by weight or more, relative to 100 parts by weight of the raw material graphite. More preferably 10 parts by weight or more, particularly preferably 12 parts by weight or more, most preferably 15 parts by weight or more, preferably 1000 parts by weight or less, more preferably 100 parts by weight or less, still more preferably 80 parts by weight or less, Particularly preferred is 50 parts by weight or less, and most preferred is 20 parts by weight or less. Within the above range, problems such as a decrease in spheroidization due to a decrease in adhesion between particles and a decrease in productivity due to adhesion of the raw carbon material to the apparatus are less likely to occur.

(Third step) Step of granulating the raw material carbon material The carbon material (A) of the present invention granulates the raw material carbon material by applying at least mechanical energy of any of impact, compression, friction, and shearing force. It is preferable to manufacture by the process to do. As an apparatus used in this step, for example, an apparatus that repeatedly gives mechanical action such as compression, friction, shearing force including interaction of raw material carbon materials mainly with impact force can be used.

Specifically, it has a rotor with a large number of blades installed inside the casing, and the rotor rotates at a high speed, so that mechanical graphite such as impact, compression, friction, and shear force is applied to the raw material graphite introduced inside. An apparatus that provides an action and performs surface treatment is preferable. Moreover, it is preferable to have a mechanism that repeatedly gives mechanical action by circulating raw material graphite.

  As such an apparatus, for example, a hybridization system (manufactured by Nara Machinery Co., Ltd.), kryptron, kryptron orb (manufactured by Earth Technica), CF mill (manufactured by Ube Industries), mechano-fusion system, nobilta, faculty ( Hosokawa Micron Co., Ltd.), Theta Composer (manufactured by Tokuju Kogakusho Co., Ltd.), COMPOSI (manufactured by Nihon Coke Industries), etc. Among these, a hybridization system manufactured by Nara Machinery Co., Ltd. is preferable.

  When processing using the apparatus, for example, the peripheral speed of the rotating rotor is preferably 30 m / second or more, more preferably 50 m / second or more, still more preferably 60 m / second or more, particularly preferably 70 m / second or more, most preferably Preferably it is 80 m / sec or more, preferably 100 m / sec or less. Within the above range, it is preferable because the fine powder can be adhered to the base material and enclosed by the base material at the same time as the spheroidization.

In addition, the treatment that gives mechanical action to the raw carbon material can be performed simply by passing the raw carbon material, but it is preferable to circulate or retain the raw carbon material in the apparatus for 30 seconds or more, More preferably, the treatment is performed by circulating or staying in the apparatus for 1 minute or more, more preferably 3 minutes or more, particularly preferably 5 minutes or more.
In the step of granulating the raw material carbon material, the raw material carbon material may be granulated in the presence of other substances. Examples of other substances include metals that can be alloyed with lithium or oxides thereof, Examples thereof include crystalline carbon and raw coke. Various types of particle structure negative electrode materials for non-aqueous secondary batteries can be manufactured by granulating together with substances other than the raw carbon material.

  In addition, the raw material carbon material, the granulating agent, and the other substances may be introduced in the whole amount into the apparatus, may be separately added, or may be continuously added. In addition, the raw carbon material, the granulating agent and the other substances may be charged simultaneously into the apparatus, may be mixed and may be charged separately. The raw material carbon material, the granulating agent, and the above-mentioned other substances may be mixed simultaneously, or the above-mentioned other substances may be added to the mixture of the raw carbon material and the granulating agent. A raw material carbon material may be added to a mixture of granules. In addition to the particle design, it can be added and mixed separately at an appropriate timing.

(4th process) The process of removing a granulating agent In this invention, you may have the process of removing the said granulating agent. Examples of the method for removing the granulating agent include a method of washing with a solvent and a method of volatilizing and decomposing and removing the granulating agent by heat treatment.
The heat treatment temperature is preferably 60 ° C. or higher, more preferably 100 ° C. or higher, further preferably 200 ° C. or higher, still more preferably 300 ° C. or higher, particularly preferably 400 ° C. or higher, most preferably 500 ° C., preferably 1500 ° C. ° C or lower, more preferably 1000 ° C or lower, still more preferably 800 ° C or lower. Within the above range, the granulating agent can be sufficiently volatilized and decomposed and productivity can be improved.

The heat treatment time is preferably 0.5 to 48 hours, more preferably 1 to 40 hours, still more preferably 2 to 30 hours, and particularly preferably 3 to 24 hours. Within the above range, the granulating agent can be sufficiently volatilized and decomposed and productivity can be improved.
The atmosphere of the heat treatment includes an active atmosphere such as an air atmosphere or an inert atmosphere such as a nitrogen atmosphere or an argon atmosphere. When heat treatment is performed at 200 ° C. to 300 ° C., there is no particular limitation, but the heat treatment is performed at 300 ° C. or higher. In the case of performing the above, an inert atmosphere such as a nitrogen atmosphere or an argon atmosphere is preferable from the viewpoint of preventing oxidation of the graphite surface.

(5th process) The process of purifying a granulated carbon material In this invention, you may have the process of purifying a granulated carbon material. Examples of a method for purifying a granulated carbon material include a method of performing an acid treatment including nitric acid and hydrochloric acid, without introducing a sulfate that can be a highly active sulfur source into the system, a metal in the carbon material, This is preferable because impurities such as metal compounds and inorganic compounds can be removed.

  The acid treatment may be performed using an acid containing nitric acid or hydrochloric acid. Other acids such as inorganic acids such as bromic acid, hydrofluoric acid, boric acid or iodic acid, or citric acid, formic acid, acetic acid, An acid in which an organic acid such as acid, trichloroacetic acid or trifluoroacetic acid is appropriately mixed can also be used. Concentrated hydrofluoric acid, concentrated nitric acid and concentrated hydrochloric acid are preferable, and concentrated nitric acid and concentrated hydrochloric acid are more preferable. In addition, although you may process a carbon material with a sulfuric acid in this invention, it shall use by the quantity and density | concentration of the grade which does not impair the effect and physical property of this invention.

  When a plurality of acids are used, for example, a combination of hydrofluoric acid, nitric acid, and hydrochloric acid is preferable because the impurities can be efficiently removed. As described above, the mixing ratio of the mixed acids when the types of acids are combined is usually 10% by mass or more, preferably 20% by mass or more, and more preferably 25% by mass or more. The upper limit is a value obtained by mixing all equal amounts (represented by 100% by mass / acid type).

The mixing ratio (mass ratio) of the carbon material and the acid in the acid treatment is usually 100: 10 or more, preferably 100: 20 or more, more preferably 100: 30 or more, and further preferably 100: 40 or more. 100: 1000 or less, preferably 100: 500 or less, more preferably 100: 300 or less.
The acid treatment is performed by immersing the carbon material in the acidic solution as described above. The immersion time is usually 0.5 to 48 hours, preferably 1 to 40 hours, more preferably 2 to 30 and even more preferably 3 to 24 hours.

The immersion temperature is usually 25 ° C. or higher, preferably 40 ° C. or higher, more preferably 50 ° C. or higher, and still more preferably 60 ° C. or higher. The theoretical upper limit in the case of using an aqueous acid is 100 ° C., which is the boiling point of water.
It is preferable to carry out further water washing for the purpose of removing the remaining acid content by acid washing and raising the pH from weakly acidic to neutral range. For example, if the treated carbon material has a pH of usually 3 or more, preferably 3.5 or more, more preferably 4 or more, and even more preferably 4.5 or more, washing with water can be omitted. If it is not within the range, it is preferable to wash with water as necessary. It is preferable to use ion-exchanged water or distilled water as the water to be washed from the viewpoint of improving the washing efficiency and preventing impurities from being mixed. The specific resistance that is an indicator of the amount of ions in water is usually 0.1 MΩ · cm or more, preferably 1 MΩ · cm or more, more preferably 10 MΩ · cm or more. The theoretical upper limit at 25 ° C. is 18.24 MΩ · cm.

The time for washing with water, that is, stirring the treated graphite and water is usually 0.5 to 48 hours, preferably 1 to 40 hours, more preferably 2 to 30 hours, still more preferably 3 to 24 hours. is there.
The mixing ratio of the treated carbon material and water is usually 100: 10 or more, preferably 100: 30 or more, more preferably 100: 50 or more, still more preferably 100: 100 or more, and 100: 1000 or less. The ratio is preferably 100: 700 or less, more preferably 100: 500 or less, and still more preferably 100: 400 or less.

The stirring temperature is usually 25 ° C. or higher, preferably 40 ° C. or higher, more preferably 50 ° C. or higher, and still more preferably 60 ° C. or higher. The upper limit is 100 ° C., which is the boiling point of water. Moreover, when performing a water washing process by a batch type, it is preferable from a viewpoint of an impurity and acid content removal to wash by repeating the process process of stirring-filtration in a pure water in multiple times. The above treatment may be repeated so that the above-mentioned treated graphite has a pH in the above range. Usually, it is 1 or more times, preferably 2 or more times, more preferably 3 or more times.
By performing the treatment as described above, the wastewater ion concentration of the obtained graphite is usually 200 ppm or less, preferably 100 ppm or less, more preferably 50 ppm or less, more preferably 30 ppm or less, and usually 1 ppm or more, preferably 2 ppm or more. More preferably, it is 3 ppm or more, and further preferably 4 ppm or more.

(6th process) The process of improving the crystallinity of a granulated carbon material In this invention, you may have the process of improving the crystallinity of a granulated carbon material. When a carbon material having low crystallinity is contained as the granulated carbon material, it is preferable to increase the crystal capacity by graphitizing the carbon material having low crystallinity in this step in order to increase the discharge capacity. In addition, the crystal on the surface of the carbon material particle may be disordered, and particularly when the above granulation process is performed, the disorder is particularly remarkable. Can be repaired.

The temperature conditions during the heat treatment are not particularly limited, but are usually 600 ° C. or higher, preferably 900 ° C. or higher, more preferably 1600 ° C. or higher, particularly preferably 2500 ° C. or higher, depending on the target degree of crystallinity. It is usually 3200 ° C. or lower, preferably 3100 ° C. or lower. The crystallinity of the carbon material particle surface can be improved as it is the said temperature conditions.
When the heat treatment is performed, the holding time for keeping the temperature condition within the above range is not particularly limited, but is usually longer than 10 seconds and not longer than 72 hours.

  The heat treatment is performed in an inert gas atmosphere such as nitrogen gas or in a non-oxidizing atmosphere using a gas generated from a carbon material. Although there is no restriction | limiting in particular as an apparatus used for heat processing, For example, a shuttle furnace, a tunnel furnace, an electric furnace, a lead hammer furnace, a rotary kiln, a direct current furnace, an Atchison furnace, a resistance heating furnace, an induction heating furnace etc. can be used.

[Composition of physical properties of carbonaceous material (B) and carbon material (A)]
The composite carbon material of the present invention contains a carbonaceous material (B) on the surface of the carbon material (A) for the purpose of suppressing side reactions with the electrolytic solution and improving rapid charge / discharge characteristics.

-Content of carbonaceous material (B) in composite carbon material Content of carbonaceous material (B) in composite carbon material of this invention is 0.01 mass% or more normally with respect to carbon material (A), Preferably Is 0.1% by mass or more, more preferably 0.5% or more, still more preferably 1% by mass or more, particularly preferably 2% by mass or more, and most preferably 3% by mass or more. It is 30% by mass or less, preferably 20% by mass or less, more preferably 15% by mass or less, further preferably 10% by mass or less, particularly preferably 7% by mass or less, and most preferably 5% by mass or less.

If the carbonaceous material (B) content in the composite carbon material is too large, the carbon material (A) will be damaged when rolled at a sufficient pressure to achieve a high capacity in the non-aqueous secondary battery. If given, material destruction occurs, and there is a tendency that charge / discharge irreversible capacity during initial cycle increases and initial efficiency decreases. On the other hand, if the content is too small, the effect of coating tends to be difficult to obtain.
Moreover, content of the carbonaceous material (B) in a composite carbon material is computable from the sample mass before and behind material baking like a following formula. At this time, the calculation is made on the assumption that there is no mass change before and after firing the carbon material (A).

Content (% by mass) of carbonaceous material (B) = [(w2-w1) / w1] × 100
(W1 is the mass (kg) of the carbon material (A), and w2 is the mass (kg) of the composite carbon material)
The amount of the carbonaceous material (B) in the composite carbon material is added when the carbonaceous material (B) and the carbonaceous material (B) precursor are combined when the carbonaceous material (B) is composited by the mixing method. It can be controlled by the amount of the carbonaceous material (B) precursor, the residual carbon ratio of the carbonaceous material (B) precursor, and the like. For example, when the residual carbon ratio of the carbonaceous material (B) precursor obtained by the method described in JIS K2270 is p%, a carbonaceous material (B) precursor that is 100 / p times the amount of the desired carbonaceous material (B) is added. Will be added. Further, when the carbonaceous material (B) is compounded by the vapor phase method, it can be controlled by the temperature, pressure, time, etc. of the carbonaceous material (B) precursor circulation.

-X-ray parameter of carbonaceous material (B) The d value (interlayer distance) of the lattice plane (002 plane) obtained by X-ray diffraction of the carbonaceous material (B) according to the present invention is preferably 0.335 nm or more. , Less than 0.340 nm. Here, the d value is more preferably 0.339 nm or less, and still more preferably 0.337 nm or less. When the d002 value is within the above range, the amount of lithium entering the graphite layer increases, and thus high charge / discharge capacity is exhibited.

The crystallite size (Lc) of the carbonaceous material (B) determined by X-ray diffraction by the Gakushin method is preferably in the range of 1.5 nm or more, more preferably 3.0 nm or more. When the amount is within the above range, the amount of lithium entering the graphite layer increases, and thus high charge / discharge capacity is exhibited. The lower limit of Lc is the theoretical value of graphite.
The X-ray parameters of the carbonaceous material (B) can be analyzed by, for example, heating and firing only the carbonaceous material (B) precursor to obtain the carbonaceous material (B).

-Compounding with the carbon material (A) In order to contain the carbonaceous material (B) on the surface of the carbon material (A), for example, an organic compound that is a precursor of the carbonaceous material (B) is uniformly added to the carbon material (A). Or a heating process in a non-oxidizing atmosphere (referred to as a mixing method in the present invention), or a vapor phase coating raw material compound that is a carbonaceous material (B) precursor to a carbon material (A). A treatment for uniformly depositing in an inert gas atmosphere (referred to as a vapor phase method in the present invention) or the like can be given. Hereinafter, the mixing method and the gas phase method will be described.

(Mixing method)
In the mixing method of the present invention, the carbon material (A) is mixed with the organic compound as the carbonaceous material (B) precursor so as to be uniformly coated, and heated in a non-oxidizing atmosphere.
Examples of the organic compound that is the carbonaceous material (B) precursor include various soft and hard coal tar pitches, carbon heavy oils such as coal tar and coal liquefied oil, petroleum oils such as crude oil normal pressure or vacuum distillation residue oil, etc. Various oils can be used, such as a heavy oil, a cracked heavy oil which is a byproduct of ethylene production by naphtha cracking.

Moreover, heat treatment pitches such as ethylene tar pitch, FCC decant oil, and Ashland pitch obtained by heat-treating cracked heavy oil can be exemplified. Furthermore, vinyl polymers such as polyvinyl chloride, polyvinyl acetate, polyvinyl butyral, and polyvinyl alcohol, substituted phenol resins such as 3-methylphenol formaldehyde resin and 3,5-dimethylphenol formaldehyde resin, and aromatics such as acenaphthylene, decacyclene, and anthracene Examples thereof include hydrocarbons, nitrogen ring compounds such as phenazine and acridine, and sulfur ring compounds such as thiophene. Examples of organic compounds that promote carbonization in the solid phase include natural polymers such as cellulose, chain vinyl resins such as polyvinylidene chloride and polyacrylonitrile, aromatic polymers such as polyphenylene, furfuryl alcohol resins, phenol- Examples thereof include thermosetting resins such as formaldehyde resin and imide resin, and thermosetting resin raw materials such as furfuryl alcohol. Among these, coal tar pitch, coal tar, coal liquefied oil, and petroleum heavy oil are preferable, and coal tar pitch, coal tar, and coal liquefied oil are particularly preferable.

  The softening point of the organic compound which is the carbonaceous material (B) precursor is usually 400 ° C. or lower, preferably 200 ° C. or lower, more preferably 150 ° C. or lower, still more preferably 100 ° C. or lower, and particularly preferably liquid at normal temperature. If it exceeds this range, it becomes difficult to mix uniformly when mixing with the carbon material (A), and it may be necessary to carry out the mixing at a high temperature. The lower limit is not particularly limited, and even a liquid that is liquid at normal temperature can be used, and is preferably normal temperature (20 ° C.) or higher.

The residual carbon ratio of the organic compound as the carbonaceous material (B) precursor is usually 1% or more, preferably 10% or more, more preferably 20% or more, still more preferably 30% or more, particularly preferably 45% or more, usually 99. % Or less, preferably 90% or less, more preferably 70% or less, and still more preferably 60% or less. The residual carbon ratio can be measured by a method based on JIS 2270, for example. When the residual carbon ratio is in the above range, the carbon material (A) surface and fine pores can be uniformly diffused and permeated, and the carbonaceous material (B) is more uniform on the carbon material (A) surface and inside the fine pores. Therefore, the average value of the microscopic Raman R value and the standard deviation (σ _R ) can be controlled within the preferable range of the present invention, and the input / output characteristics tend to be improved.

The amount of carbonaceous material (B) precursor added is usually 0.1 times the pore volume of the carbon material (A) in the range of 0.01 μm or more and 1 μm or less on the volume basis (= mass / density). Or more, preferably 0.5 times or more, more preferably 0.7 times or more, still more preferably 0.8 times or more, particularly preferably 0.9 times or more, most preferably 0.95 times or more, usually 10 times or less. The ratio is preferably 5 times or less, more preferably 3 times or less, still more preferably 2 times or less, particularly preferably 1.4 times or less, and most preferably 1.2 times or less. Within the above range, the carbon material (A) can sufficiently penetrate into the pores in the range of 0.01 μm or more and 1 μm or less, and excess carbonaceous material (B) precursor overflows from the pores. Therefore, the carbonaceous material (B) precursor can be diffused and penetrated uniformly on the surface of the carbon material (A) and inside the micropores. There is a tendency that the average value and standard deviation (σ _R ) of the microscopic Raman R values of the 30 composite carbon materials selected in the above can be controlled within the preferable range of the present invention.

  Furthermore, a solvent etc. can be added and diluted to a carbonaceous material (B) precursor as needed. By adding a solvent or the like, it becomes possible to reduce the viscosity of the carbonaceous material (B) precursor, and improve the permeability of the carbon material (A) into pores in the range of 0.01 μm to 1 μm, There exists a tendency for a carbonaceous material (B) precursor to spread | diffuse and osmose | permeate uniformly by the surface of a carbon material (A), and the inside of a micropore.

  The carbon material (A), the carbonaceous material (B) precursor, and raw materials such as a solvent, if necessary, are mixed under heating as necessary. Thereby, it will be in the state by which the liquid carbonaceous material (B) precursor was attached to the carbon material (A) and the raw material which does not melt at the compounding temperature. In this case, all the raw materials may be charged into the mixer and mixing and heating may be performed at the same time. Components other than the carbonaceous material (B) precursor may be charged into the mixer and heated in a stirred state, and the temperature may be increased to the mixing temperature. After rising, a carbonaceous material (B) precursor at room temperature or in a vulcanized molten state may be charged.

  The heating temperature is usually higher than the softening point of the carbonaceous material (B) precursor, preferably higher than the softening point by 10 ° C or higher, more preferably higher than the softening point by 20 ° C or higher, usually lower than 450 ° C, preferably 250 ° C. It is carried out at a temperature below ℃. If the heating temperature is too low, the viscosity of the carbonaceous material (B) precursor becomes high and mixing becomes difficult and the coating form may become uneven. If the heating temperature is too high, the volatilization of the carbonaceous material (B) precursor will occur. The polycondensation increases the viscosity of the mixed system, making mixing difficult and the coating form non-uniform.

  The combination machine is preferably a model having a stirring blade, and the stirring blade may be a general-purpose one such as a Z type or a gusset type. The amount of raw material charged into the compounding machine is usually 10% by volume or more, preferably 15% by volume or more, and 50% by volume or less, preferably 30% by volume or less of the volume of the mixer. The mixing time is 5 minutes or more, and is the time until the maximum viscosity change due to the volatilization of the volatile matter at the longest, usually 30 to 120 minutes. The compounding machine is preferably preheated to the compounding temperature prior to compounding.

  The heating temperature (firing temperature) varies depending on the carbonaceous material (B) precursor used for the preparation of the mixture, but is usually 800 ° C. or higher, preferably 900 ° C. or higher, more preferably 950 ° C. or higher. Carbonized or graphitized. The upper limit of the heating temperature is a temperature at which the carbide of the carbonaceous material (B) precursor does not reach a crystal structure equivalent to the crystal structure of the flake graphite in the mixture, and is usually 3500 ° C. at the highest. The upper limit of the heating temperature is preferably 3000 ° C, preferably 2000 ° C, more preferably 1500 ° C.

  In order to prevent oxidation, the atmosphere during the heat treatment is performed under a non-oxidizing atmosphere in which an inert gas such as nitrogen or argon is circulated or a granular carbon material such as breeze or packing coke is filled in the gap. The equipment used for the heat treatment is a reactor such as a shuttle furnace, tunnel furnace, reed hammer furnace, rotary kiln, autoclave, coker (heat treatment tank for coke production), electric furnace, gas furnace, Acheson furnace for electrode materials, etc. As long as it conforms to the above, there is no particular limitation, and the heating rate, cooling rate, heat treatment time, etc. can be arbitrarily set within the allowable range of the equipment used.

(Gas phase method)
As the vapor phase method, there is a treatment such as a CVD (Chemical Vapor Deposition) method in which a vapor phase coating raw material compound that is a carbonaceous material (B) precursor is uniformly deposited on the surface of the carbon material (A) in an inert gas atmosphere. Can be mentioned.
As a vapor phase coating raw material compound that is a specific carbonaceous material (B) precursor, a gaseous compound that can be decomposed by heat, plasma, or the like to form a carbonaceous material (B) film on the surface of the carbon material (A). Can be used. Examples of the gaseous compound include unsaturated aliphatic hydrocarbons such as ethylene, acetylene and propylene, saturated aliphatic hydrocarbons such as methane, ethane and propane, and aromatic hydrocarbons such as benzene, toluene and naphthalene. These compounds may be used alone or as a mixed gas of two or more. The temperature, pressure, time and the like for performing the CVD treatment can be appropriately selected according to the type of the coating raw material used and the desired amount of the coated carbonaceous material (B).

Even when the carbonaceous material (B) is combined with the carbon material (A) by the vapor phase method, the pore volume in the range of 0.01 μm or more and 1 μm or less of the carbon material (A) is 0.07 mL / g or more, PD By adjusting the pore volume and the pore diameter so that the / d50 (%) is 1.8 or less, the vapor phase coating raw material compound is difficult to contact the carbon material (A) particles, and also inside the contact portion and inside the particles. Since it becomes possible to diffuse through the pores, and the carbonaceous material (B) can be uniformly coated on the surface of the carbon material (A) and inside the fine pores, it was selected at random. There exists a tendency which can control the average value of micro Raman R value of 30 composite carbon materials, and standard deviation ((sigma) _R ) to the preferable range of this invention.

(Other processes)
After the treatment by the mixing method or the gas phase method described above, the composite carbon material of the present invention can be obtained by performing crushing and / or grinding treatment, classification treatment, and the like as necessary.
Although the shape is arbitrary, the average particle diameter is usually 2 to 50 μm, preferably 5 to 35 μm, and particularly 8 to 30 μm. Crushing and / or crushing and / or classification is performed as necessary so that the particle size is in the above range.
In addition, as long as the effect of this invention is not impaired, you may add the addition of another process and the control conditions which are not described above.

<Mixing with other carbon materials>
Further, in the present invention, a carbon material different from the composite carbon material is mixed for the purpose of improving the orientation of the electrode plate, the permeability of the electrolytic solution, the conductive path, etc., and improving the cycle characteristics, electrode plate swelling, etc. (Hereinafter, a carbon material obtained by mixing the composite carbon material with a carbon material different from the composite carbon material may be referred to as a “mixed carbon material”).

  The carbon material different from the composite carbon material is selected from, for example, natural graphite, artificial graphite, coated graphite obtained by coating a carbon material with a carbonaceous material, amorphous carbon, and a carbon material containing metal particles or a metal compound. Materials can be used. Moreover, you may mix the said carbon material (A). Any one of these materials may be used alone, or two or more of these materials may be used in any combination and composition.

  As the natural graphite, for example, a highly purified carbon material or a spherical natural graphite can be used. In the present invention, high purification means that ash contained in low-purity natural graphite is usually treated in an acid such as hydrochloric acid, sulfuric acid, nitric acid, hydrofluoric acid, or a combination of a plurality of acid treatment steps. It means an operation of dissolving and removing metal and metal, etc., and usually, after the acid treatment step, a water washing treatment or the like is performed to remove the acid content used in the high purification treatment step. Moreover, you may evaporate and remove ash, a metal, etc. by processing at high temperature 2000 degreeC or more instead of an acid treatment process. Moreover, you may remove ash, a metal, etc. by processing in halogen gas atmosphere, such as chlorine gas, at the time of high temperature heat processing. Furthermore, these methods may be used in any combination.

The volume-based average particle diameter of natural graphite is usually 5 μm or more, preferably 8 μm or more, more preferably 10 μm or more, particularly preferably 12 μm or more, and usually 60 μm or less, preferably 40 μm or less, particularly preferably 30 μm or less. . If the average particle diameter is within this range, it is preferable because high-speed charge / discharge characteristics and processability are improved.
Natural graphite has a BET specific surface area of usually 1 m ² / g or more, preferably 2 m ² / g or more, and usually 30 m ² / g or less, preferably 15 m ² / g or less. If the specific surface area is within this range, it is preferable because high-speed charge / discharge characteristics and processability are improved.

The tap density of natural graphite is usually preferably 0.6 g / cm ³ or more, 0.7 g / cm ³ or more, more preferably 0.8 g / cm ³ or more, and further preferably 0.85 g / cm ³ or more. Moreover, 1.3 g / cm ³ or less and 1.2 g / cm ³ or less are usually preferable, and 1.1 g / cm ³ or less is more preferable. If it is this range, since a high-speed charge / discharge characteristic and process property become favorable, it is preferable.

Examples of the artificial graphite include particles obtained by graphitizing a carbon material. For example, a single graphite precursor particle is fired while being powdered, a graphitized particle, and a plurality of graphite precursor particles are molded and fired. Granulated particles that have been graphitized and crushed can be used.
The volume-based average particle size of artificial graphite is usually 5 μm or more, preferably 10 μm or more, and usually 60 μm or less, preferably 40 μm, more preferably 30 μm or less. If it is this range, since suppression of an electrode plate swelling and process property become favorable, it is preferable.
BET specific surface area of the artificial graphite is usually 0.5 m ² / g or more, preferably 1.0 m ² / g or more and usually ^8m 2 / g or less, preferably ^{6 m} 2 / g or less, more preferably ^4m 2 / It is the range below g. If it is this range, since suppression of an electrode plate swelling and process property become favorable, it is preferable.

Further, the tap density of the artificial graphite is usually preferably 0.6 g / cm ³ or more, 0.7 g / cm ³ or more, more preferably 0.8 g / cm ³ or more, and further preferably 0.85 g / cm ³ or more. Moreover, normally 1.5 g / cm < ³ > or less and 1.4 g / cm < ³ > or less are preferable, and 1.3 g / cm < ³ > or less is more preferable. If it is this range, since suppression of an electrode plate swelling and process property become favorable, it is preferable.

Examples of the coated graphite obtained by coating a carbon material with a carbonaceous material include, for example, particles obtained by coating, firing and / or graphitizing an organic compound which is a precursor of the above-described carbonaceous material on natural graphite or artificial graphite, natural graphite or artificial graphite. In addition, particles obtained by coating a carbonaceous material by CVD can be used.
The volume-based average particle diameter of the coated graphite is usually 5 μm or more, preferably 8 μm or more, more preferably 10 μm or more, particularly preferably 12 μm or more, and usually 60 μm or less, preferably 40 μm or less, particularly preferably 30 μm or less. . If the average particle diameter is within this range, it is preferable because high-speed charge / discharge characteristics and processability are improved.

The BET specific surface area of the coated graphite is usually 1 m ² / g or more, preferably 2 m ² / g or more, more preferably 2.5 m ² / g or more, and usually 20 m ² / g or less, preferably 10 m ² / g or less. More preferably, it is 8 m ² / g or less, particularly preferably 5 m ² / g or less. If the specific surface area is within this range, it is preferable because high-speed charge / discharge characteristics and processability are improved.
The tap density of the coated graphite is usually preferably 0.6 g / cm ³ or more, 0.7 g / cm ³ or more, more preferably 0.8 g / cm ³ or more, and further preferably 0.85 g / cm ³ or more. Moreover, 1.3 g / cm ³ or less and 1.2 g / cm ³ or less are usually preferable, and 1.1 g / cm ³ or less is more preferable. A tap density in this range is preferable because high-speed charge / discharge characteristics and processability are improved.

As amorphous carbon, for example, particles obtained by firing a bulk mesophase or particles obtained by infusibilizing an easily graphitizable organic compound and firing can be used.
The volume-based average particle size of the amorphous carbon is usually in the range of 5 μm or more, preferably 12 μm or more, and usually 60 μm or less, preferably 40 μm or less. If it is this range, since a high-speed charge / discharge characteristic and process property become favorable, it is preferable.

BET specific surface area of the amorphous carbon is usually ^{1 m} 2 / g or more, preferably ^2m 2 / g or more, more preferably 2.5 m ² / g or more and usually ^8m 2 / g or less, preferably ^{6 m} 2 / g or less, more preferably 4 m ² / g or less. If the specific surface area is within this range, it is preferable because high-speed charge / discharge characteristics and processability are improved.
Moreover, the tap density of amorphous carbon is usually preferably 0.6 g / cm ³ or more, preferably 0.7 g / cm ³ or more, more preferably 0.8 g / cm ³ or more, and further more preferably 0.85 g / cm ³ or more. preferable. Moreover, 1.3 g / cm ³ or less and 1.2 g / cm ³ or less are usually preferable, and 1.1 g / cm ³ or less is more preferable. A tap density in this range is preferable because high-speed charge / discharge characteristics and processability are improved.

Carbon materials containing metal particles and metal compounds include, for example, Fe, Co, Sb, Bi, Pb, Ni, Ag, Si, Sn, Al, Zr, Cr, P, S, V, Mn, Nb, Mo, Examples thereof include a material in which a metal selected from the group consisting of Cu, Zn, Ge, In, Ti, or the like or a compound thereof is combined with graphite. As the metal or the compound that can be used, an alloy composed of two or more kinds of metals may be used, and the metal particles may be alloy particles formed of two or more kinds of metal elements. Among these, a metal selected from the group consisting of Si, Sn, As, Sb, Al, Zn and W or a compound thereof is preferable, and Si and SiOx are particularly preferable. This general formula SiOx is obtained using Si dioxide (SiO ₂ ) and metal Si (Si) as raw materials, and the value of x is usually 0 <x <2, preferably 0.2 or more, 1.8 Hereinafter, more preferably 0.4 or more and 1.6 or less, and further preferably 0.6 or more and 1.4 or less. If it is this range, it becomes high capacity | capacitance and it becomes possible to reduce the irreversible capacity | capacitance by the coupling | bonding of Li and oxygen.

  The volume-based average particle diameter of the metal particles is usually 0.005 μm or more, preferably 0.01 μm or more, more preferably 0.02 μm or more, further preferably 0.03 μm or more, and usually 10 μm or less from the viewpoint of cycle life. , Preferably 9 μm or less, more preferably 8 μm or less. When the average particle size is within this range, volume expansion associated with charge / discharge is reduced, and good cycle characteristics can be obtained while maintaining charge / discharge capacity.

BET specific surface area of the metal particles is usually 0.5 m ² / g or more 120 m ² / g or less and a ^{1 m} 2 / g or more 100m ² / g or less. When the specific surface area is within the above range, the charge / discharge efficiency and discharge capacity of the battery are high, lithium is quickly taken in and out during high-speed charge / discharge, and the rate characteristics are excellent.
The apparatus used for mixing the composite carbon material and the carbon material different from the composite carbon material is not particularly limited. For example, in the case of a rotary mixer: a cylindrical mixer, a twin cylinder mixer, Double cone type mixer, regular cubic type mixer, vertical type mixer, stationary type mixer: spiral type mixer, ribbon type mixer, Muller type mixer, Helical Flight type mixer, P
An ugmill type mixer, a fluidized type mixer, or the like can be used.

<Negative electrode for non-aqueous secondary battery>
The negative electrode for a non-aqueous secondary battery of the present invention (hereinafter also referred to as “electrode sheet” as appropriate) includes a current collector and a negative electrode active material layer formed on the current collector, and the active material layer is at least The composite carbon material of the present invention is contained. More preferably, it contains a binder.
As the binder, one having an olefinically unsaturated bond in the molecule is used. The type is not particularly limited, and specific examples include styrene-butadiene rubber, styrene / isoprene / styrene rubber, acrylonitrile-butadiene rubber, butadiene rubber, and ethylene / propylene / diene copolymer. By using such a binder having an olefinically unsaturated bond, the swellability of the active material layer with respect to the electrolytic solution can be reduced. Of these, styrene-butadiene rubber is preferred because of its availability.

  By using a binder having such an olefinically unsaturated bond in combination with the above active material, the strength of the negative electrode plate can be increased. When the strength of the negative electrode is high, deterioration of the negative electrode due to charge / discharge is suppressed, and the cycle life can be extended. In addition, since the negative electrode according to the present invention has high adhesive strength between the active material layer and the current collector, even when the binder content in the active material layer is reduced, the negative electrode is wound to produce a battery. It is speculated that the problem that the active material layer peels from the current collector does not occur.

As the binder having an olefinically unsaturated bond in the molecule, one having a large molecular weight or one having a large proportion of unsaturated bonds is desirable. Specifically, in the case of a binder having a high molecular weight, the weight average molecular weight is preferably 10,000 or more, more preferably 50,000 or more, and preferably 1,000,000 or less, more preferably 300,000 or less. Is desirable. In the case of a binder having a large ratio of unsaturated bonds, the number of moles of olefinically unsaturated bonds per gram of all binders is preferably 2.5 × 10 ⁻⁷ or more, more preferably 8 × 10 ^{−. It} is desirable that the amount is ⁷ mol or more, preferably 1 × 10 ⁻⁶ mol or less, more preferably 5 × 10 ⁻⁶ mol or less. The binder only needs to satisfy at least one of these regulations regarding molecular weight and regulations regarding the proportion of unsaturated bonds, but it is more preferable to satisfy both regulations simultaneously. When the molecular weight of the binder having an olefinically unsaturated bond is within the above range, mechanical strength and flexibility are excellent.

The binder having an olefinically unsaturated bond has an unsaturation degree of preferably 15% or more, more preferably 20% or more, still more preferably 40% or more, and preferably 90% or less, more preferably 80%. % Or less. The degree of unsaturation represents the ratio (%) of the double bond to the repeating unit of the polymer.
In the present invention, a binder that does not have an olefinically unsaturated bond can also be used in combination with the above-described binder that has an olefinically unsaturated bond as long as the effects of the present invention are not lost. The mixing ratio of the binder having no olefinically unsaturated bond to the binder having an olefinically unsaturated bond is preferably 150% by mass or less, more preferably 120% by mass or less.

By using a binder that does not have an olefinically unsaturated bond, the coatability can be improved. However, if the combined amount is too large, the strength of the active material layer is lowered.
Examples of the binder having no olefinic unsaturated bond include thickening polysaccharides such as methylcellulose, carboxymethylcellulose, starch, carrageenan, pullulan, guar gum, xanthan gum (xanthan gum), polyethers such as polyethylene oxide and polypropylene oxide, Vinyl alcohols such as polyvinyl alcohol and polyvinyl butyral, polyacids such as polyacrylic acid and polymethacrylic acid, or metal salts of these polymers, fluorine-containing polymers such as polyvinylidene fluoride, alkane polymers such as polyethylene and polypropylene, and these A copolymer etc. are mentioned.

  When the composite carbon material of the present invention is used in combination with the above-mentioned binder having an olefinically unsaturated bond, the ratio of the binder used for the active material layer can be reduced as compared with the conventional one. Specifically, the composite carbon material of the present invention and a binder (this may be a mixture of a binder having an unsaturated bond and a binder having no unsaturated bond as described above). The mass ratio is preferably 90/10 or more, more preferably 95/5 or more, preferably 99.9 / 0.1 or less, more preferably 99.5 / 0. The range is 5 or less. When the ratio of the binder is within the above range, a decrease in capacity and an increase in resistance can be suppressed, and the electrode plate strength is also excellent.

  The negative electrode of the present invention is formed by dispersing the above-described composite carbon material of the present invention and a binder in a dispersion medium to form a slurry, which is applied to a current collector. As the dispersion medium, an organic solvent such as alcohol or water can be used. If necessary, a conductive agent may be added to the slurry. Examples of the conductive agent include carbon black such as acetylene black, ketjen black, and furnace black, and fine powder made of Cu, Ni having an average particle diameter of 1 μm or less, or an alloy thereof. The addition amount of the conductive agent is preferably about 10% by mass or less with respect to the composite carbon material of the present invention.

A conventionally well-known thing can be used as a collector which apply | coats a slurry. Specific examples include metal thin films such as rolled copper foil, electrolytic copper foil, and stainless steel foil. The thickness of the current collector is preferably 4 μm or more, more preferably 6 μm or more, preferably 30 μm or less, more preferably 20 μm or less.
After applying the slurry on the current collector, it is preferably 60 ° C. or higher, more preferably 80 ° C. or higher, and preferably 200 ° C. or lower, more preferably 195 ° C. or lower, in dry air or an inert atmosphere. Dry to form an active material layer.

  The thickness of the active material layer obtained by applying and drying the slurry is preferably 5 μm or more, more preferably 20 μm or more, still more preferably 30 μm or more, and preferably 200 μm or less, more preferably 100 μm or less, still more preferably. 75 μm or less. When the thickness of the active material layer is within the above range, it is excellent in practicality as a negative electrode in consideration of the particle size of the active material, and a sufficient Li occlusion / release function for a high-density current value can be obtained. .

The density of the carbon material in the active material layer varies depending on the application, but in an application in which capacity is important, it is preferably 1.55 g / cm ³ or more, more preferably 1.6 g / cm ³ or more, and still more preferably 1.65 g / cm ³ or more, particularly preferably 1.7 g / cm ³ or more. Moreover, Preferably it is 1.9 g / cm < ³ > or less. When the density is within the above range, a sufficient battery capacity per unit volume can be secured, and the rate characteristics are hardly lowered.

  When producing a negative electrode for a non-aqueous secondary battery using the composite carbon material of the present invention described above, the method and selection of other materials are not particularly limited. Moreover, when producing a lithium ion secondary battery using this negative electrode, there is no particular limitation on the selection of members necessary for the battery configuration such as the positive electrode and the electrolytic solution constituting the lithium ion secondary battery. Hereinafter, the details of the negative electrode for lithium ion secondary battery and the lithium ion secondary battery using the carbon material of the present invention will be exemplified, but usable materials, production methods and the like are not limited to the following specific examples. Absent.

<Non-aqueous secondary battery>
The basic configuration of the non-aqueous secondary battery of the present invention, particularly the lithium ion secondary battery, is the same as that of a conventionally known lithium ion secondary battery, and is usually a positive electrode and a negative electrode capable of inserting and extracting lithium ions, and an electrolyte. Is provided. The negative electrode of the present invention described above is used as the negative electrode.
The positive electrode is obtained by forming a positive electrode active material layer containing a positive electrode active material and a binder on a current collector.

Examples of the positive electrode active material include metal chalcogen compounds that can occlude and release alkali metal cations such as lithium ions during charge and discharge. Examples of metal chalcogen compounds include vanadium oxide, molybdenum oxide, manganese oxide, chromium oxide, titanium oxide, tungsten oxide and other transition metal oxides, vanadium sulfide, molybdenum sulfide. , Transition metal sulfides such as titanium sulfide, transition metal sulfides such as NiS ₃ and FePS ₃ , selenium compounds of transition metals such as VSe ₂ and NbSe ₃ , Fe _0.25 V _0. Examples thereof include composite oxides of transition metals such as ₇₅ S ₂ and Na _0.1 CrS ₂ and composite sulfides of transition metals such as LiCoS ₂ and LiNiS ₂ .

Among these, V ₂ O ₅ , V ₅ O ₁₃ , VO ₂ , Cr ₂ O ₅ , MnO ₂ , TiO ₂ , MoV ₂ O ₈ , LiCoO ₂ , LiNiO ₂ , LiMn ₂ O ₄ , TiS ₂ , V ₂ S ₅ , Cr _0.25 V _0.75 S ₂ , Cr _0.5 V _0.5 S _{2 and the} like are preferable, and LiCoO ₂ , LiNiO ₂ , LiMn ₂ O ₄ and some of these transition metals are particularly preferable. Is a lithium transition metal composite oxide in which is substituted with another metal. These positive electrode active materials may be used alone or in combination.

  A known binder can be arbitrarily selected and used as the binder for binding the positive electrode active material. Examples include inorganic compounds such as silicate and water glass, and resins having no unsaturated bond such as Teflon (registered trademark) and polyvinylidene fluoride. Among these, a resin having no unsaturated bond is preferable. If a resin having an unsaturated bond is used as the resin for binding the positive electrode active material, the resin may be decomposed during the oxidation reaction. The weight average molecular weight of these resins is usually 10,000 or more, preferably 100,000 or more, and usually 3 million or less, preferably 1 million or less.

The positive electrode active material layer may contain a conductive material in order to improve the conductivity of the electrode. The conductive agent is not particularly limited as long as it can be mixed with an active material in an appropriate amount to impart conductivity, but is usually carbon powder such as acetylene black, carbon black, and graphite, various metal fibers, powder, and foil. Etc.
The positive electrode plate is formed by slurrying a positive electrode active material or a binder with a solvent in the same manner as in the production of the negative electrode as described above, and applying and drying on a current collector. As the positive electrode current collector, aluminum, nickel, stainless steel (SUS), or the like is used, but is not limited at all.

As the electrolyte, a non-aqueous electrolyte obtained by dissolving a lithium salt in a non-aqueous solvent, or a gel, rubber, or solid sheet obtained by using an organic polymer compound or the like from the non-aqueous electrolyte is used.
The non-aqueous solvent used in the non-aqueous electrolyte is not particularly limited, and can be appropriately selected from known non-aqueous solvents that have been conventionally proposed as solvents for non-aqueous electrolytes. For example, chain carbonates such as diethyl carbonate, dimethyl carbonate and ethyl methyl carbonate; cyclic carbonates such as ethylene carbonate, propylene carbonate and butylene carbonate; chain ethers such as 1,2-dimethoxyethane; tetrahydrofuran, 2-methyl Examples include cyclic ethers such as tetrahydrofuran, sulfolane, and 1,3-dioxolane; chain esters such as methyl formate, methyl acetate, and methyl propionate; and cyclic esters such as γ-butyrolactone and γ-valerolactone.

  Any one of these non-aqueous solvents may be used alone, or two or more thereof may be mixed and used. In the case of a mixed solvent, a combination of a mixed solvent containing a cyclic carbonate and a chain carbonate is preferable, and the cyclic carbonate is a mixed solvent of ethylene carbonate and propylene carbonate. This is particularly preferable from the viewpoint that the impossible characteristics are improved. Among these, propylene carbonate is preferably in a range of 2% by mass to 80% by mass, more preferably in a range of 5% by mass to 70% by mass, and further in a range of 10% by mass to 60% by mass with respect to the entire non-aqueous solvent. preferable. When the proportion of propylene carbonate is lower than the above, the ionic conductivity at low temperature decreases, and when the proportion of propylene carbonate is higher than the above, when a graphite-based electrode is used, propylene carbonate solvated with lithium ions enters between the graphite phases. The co-insertion causes a delamination degradation of the graphite-based negative electrode active material, and there is a problem that a sufficient capacity cannot be obtained.

The lithium salt used in the non-aqueous electrolytic solution is not particularly limited, and can be appropriately selected from known lithium salts that can be used for this purpose. For example, halides such as LiCl and LiBr, perhalogenates such as LiClO ₄ , LiBrO ₄ and LiClO ₄ , inorganic lithium salts such as inorganic fluoride salts such as LiPF ₆ , LiBF ₄ and LiAsF ₆ , LiCF ₃ SO ₃ , Fluorine-containing organic lithium salts such as perfluoroalkanesulfonic acid salts such as LiC ₄ F ₉ SO ₃ and perfluoroalkanesulfonic acid imide salts such as Li trifluorosulfonimide ((CF ₃ SO ₂ ) ₂ NLi) Of these, LiClO ₄ , LiPF ₆ , and LiBF ₄ are preferable.

Lithium salts may be used alone or in combination of two or more. The concentration of the lithium salt in the nonaqueous electrolytic solution is usually in the range of 0.5 mol / L or more and 2.0 mol / L or less.
In addition, when an organic polymer compound is included in the above non-aqueous electrolyte and used in the form of a gel, rubber, or solid sheet, specific examples of the organic polymer compound include polyethylene oxide, polypropylene oxide, and the like. Polyether polymer compounds; Cross-linked polymers of polyether polymer compounds; Vinyl alcohol polymer compounds such as polyvinyl alcohol and polyvinyl butyral; Insolubilized vinyl alcohol polymer compounds; Polyepichlorohydrin; Polyphosphazene; Siloxane; vinyl polymer compounds such as polyvinylpyrrolidone, polyvinylidene carbonate, polyacrylonitrile; poly (ω-methoxyoligooxyethylene methacrylate), poly (ω-methoxyoligooxyethylene methacrylate-co-methyl methacrylate) Rate) and polymer copolymers such as poly (hexafluoropropylene-vinylidene fluoride).

The non-aqueous electrolyte solution described above may further contain a film forming agent. Specific examples of the film forming agent include carbonate compounds such as vinylene carbonate, vinylethyl carbonate, and methylphenyl carbonate; alken sulfides such as ethylene sulfide and propylene sulfide; sultone compounds such as 1,3-propane sultone and 1,4-butane sultone And acid anhydrides such as maleic acid anhydride and succinic acid anhydride. Furthermore, an overcharge inhibitor such as diphenyl ether or cyclohexylbenzene may be added. When the above additives are used, the content is usually 10% by mass or less, preferably 8% by mass or less, more preferably 5% by mass or less, and particularly preferably 2% by mass or less. If the content of the additive is too large, other battery characteristics such as an increase in initial irreversible capacity, low temperature characteristics, and deterioration in rate characteristics may be adversely affected.

Further, as the electrolyte, a polymer solid electrolyte which is a conductor of an alkali metal cation such as lithium ion can be used. Examples of the polymer solid electrolyte include a polymer in which a lithium salt is dissolved in the aforementioned polyether polymer compound, and a polymer in which the terminal hydroxyl group of the polyether is substituted with an alkoxide.
In order to prevent a short circuit between the electrodes, a porous separator such as a porous film or a nonwoven fabric is usually interposed between the positive electrode and the negative electrode. In this case, the nonaqueous electrolytic solution is used by impregnating a porous separator. As a material for the separator, polyolefin such as polyethylene and polypropylene, polyethersulfone, and the like are used, and polyolefin is preferable.

  The form of the nonaqueous secondary battery of the present invention is not particularly limited. Examples include a cylinder type in which a sheet electrode and a separator are spiral, a cylinder type having an inside-out structure in which a pellet electrode and a separator are combined, a coin type in which a pellet electrode and a separator are stacked, and the like. In addition, by storing batteries of these forms in an optional outer case, the battery can be used in an arbitrary shape such as a coin shape, a cylindrical shape, or a square shape.

  The procedure for assembling the non-aqueous secondary battery of the present invention is not particularly limited, and may be assembled by an appropriate procedure according to the structure of the battery. For example, the negative electrode is placed on the outer case, and the electrolytic solution is placed thereon. A separator is provided, and a positive electrode is placed so as to face the negative electrode, and it is caulked together with a gasket and a sealing plate to form a battery.

  EXAMPLES Next, specific embodiments of the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

<Production of electrode sheet>
An electrode plate having an active material layer having an active material layer density of 1.35 ± 0.03 g / cm ³ was prepared using the graphite particles of the example or the comparative example. Specifically, 50.00 ± 0.02 g of negative electrode material, 50.00 ± 0.02 g of 1 mass% carboxymethylcellulose sodium salt aqueous solution (0.500 g in terms of solid content), and styrene having a weight average molecular weight of 270,000 -Aqueous dispersion of butadiene rubber 1.00 ± 0.05 g (0.5 g in terms of solid content) was stirred for 5 minutes with a hybrid mixer manufactured by Keyence and defoamed for 30 seconds to obtain a slurry.
This slurry was 10 cm wide using a small die coater made by ITOCHU machining so that the negative electrode material adhered to 6.00 ± 0.3 mg / cm ² on a 10 μm thick copper foil as a current collector.
And roll-pressing using a roller having a diameter of 20 cm to adjust the density of the active material layer to 1.35 ± 0.03 g / cm ³ to obtain an electrode sheet.

<Production method of non-aqueous secondary battery (laminated battery)>
The electrode sheet produced by the above method was cut into 4 cm × 3 cm to form a negative electrode, a positive electrode made of NMC was cut out with the same area, and a separator (made of a porous polyethylene film) was placed between the negative electrode and the positive electrode for combination. A laminate type battery was prepared by injecting 200 μl of an electrolytic solution in which LiPF ₆ was dissolved in a mixed solvent of ethylene carbonate, ethyl methyl carbonate, and dimethyl carbonate (volume ratio = 3: 3: 4) to a concentration of 1.2 mol / L. Was made.

<Low temperature output characteristics>
Using the laminate type non-aqueous electrolyte secondary battery produced by the method for producing the non-aqueous electrolyte secondary battery, low temperature output characteristics were measured by the following measuring method.
For non-aqueous electrolyte secondary batteries that have not undergone charge / discharge cycles, a voltage range of 4.1 V to 3.0 V at 25 ° C., a current value of 0.2 C (the rated capacity with a discharge capacity of 1 hour rate is discharged in 1 hour) 3C for the current value to be 1C, the same applies hereinafter), voltage range of 4.2V to 3.0V, current value of 0.2C (at the time of charging 4.2V constant voltage charging for another 2.5 hours) Implementation) Initial charge and discharge was performed for 2 cycles.

  Furthermore, after charging at a current value of 0.2 C to SOC 50%, in a low temperature environment of −30 ° C., each current value of 1/8 C, 1/4 C, 1/2 C, 1.5 C, 2 C is 2 seconds. Measure the drop in battery voltage after 2 seconds of discharge under each condition, and calculate the current value I that can flow for 2 seconds when the upper limit of charge voltage is 3V. The value calculated by the formula 3 × I (W) was used as the low temperature output characteristic of each battery.

<Average value of micro Raman R value, standard deviation (σ _R ), Raman R ₁₅ value>
Using a Raman spectrometer (Nicolet Almega XR manufactured by Thermo Fisher Scientific), the micro Raman measurement was performed under the following conditions, and the average value of the micro Raman R value and the standard deviation (σ _R ) were calculated.
The particle to be measured is naturally dropped on the sample stage, the surface is flattened, and micro Raman measurement is performed.

Excitation wavelength: 532 nm
Laser power on sample: 1 mW or less Resolution: 10 cm ⁻¹
Irradiation diameter: 1μmΦ
Measurement range: 400 cm ^{−1 to} 4000 cm ⁻¹
Peak intensity measurement: Linear baseline correction in a range of about ^{1100cm -1 ~1750cm} -1.

Calculation method of the Raman R value: peak intensity of the peak intensity _{I A} to peak top of a peak _{P A} around 1580 cm ^-1 in the spectrum after the linear baseline correction, to the peak top of a peak _{P B} in the vicinity of 1360 cm ^-1 I _B was read, the R value (I _B / I _A ) was calculated, and the average value and standard deviation (σ _R ) were calculated.
Raman R ₍₁₅₎ Calculation method of value (%): Number of composite carbon materials that are 0.15 or less of micro Raman R values of 30 randomly selected composite carbon materials / 30 × 100
<D50>
A carbon material (0.01 g) is suspended in 10 mL of a 0.2 mass% aqueous solution of polyoxyethylene sorbitan monolaurate (for example, Tween 20 (registered trademark)), which is a surfactant, and this is a measurement sample. And introduced into a commercially available laser diffraction / scattering particle size distribution measuring apparatus (for example, LA-920 manufactured by HORIBA), and the measurement sample was irradiated with 28 kHz ultrasonic waves at an output of 60 W for 1 minute, and then the volume-based median diameter was measured in the measuring apparatus. As measured.

<Mode pore diameter (PD) in the range of 0.01 μm or more and 1 μm or less, half-width of the pore distribution (log (nm)), pore volume in the range of 0.01 μm or more and 1 μm or less, total pore volume>
As a measurement of the mercury intrusion method, a mercury porosimeter (Autopore 9520 manufactured by Micromeritex Co., Ltd.) was used, and a sample (negative electrode material) was weighed in an amount of about 0.2 g in a powder cell,
After performing deaeration pretreatment for 10 minutes at room temperature under vacuum (50 μmHg or less), the pressure was reduced in steps to 4 psia, mercury was introduced, the pressure was increased in steps from 4 psia to 40000 psia, and the pressure was further decreased to 25 psia. . The pore distribution was calculated from the obtained mercury intrusion curve using the Washburn equation. Note that the surface tension of mercury was calculated as 485 dyne / cm and the contact angle was 140 °.

  From the obtained pore distribution, the mode pore diameter (PD) in the range of 0.01 μm to 1 μm, the pore volume in the range of 0.01 μm to 1 μm, and the total pore volume were calculated. In addition, when the horizontal axis of the obtained pore distribution (nm) is expressed in the common logarithm (log (nm)), the half-value half width on the micropore side of the peak existing in the range of 0.01 μm or more and 1 μm or less It is defined as the pore distribution half width at half maximum (log (nm)).

<BET specific surface area (SA)>
Using a surface area meter (Shimadzu Corporation specific surface area measuring device “Gemini 2360”), the carbon material sample was subjected to preliminary vacuum drying at 100 ° C. for 3 hours under nitrogen flow, then cooled to liquid nitrogen temperature, and atmospheric pressure. Using a nitrogen helium mixed gas accurately adjusted so that the value of the relative pressure of nitrogen to 0.3 is 0.3, the nitrogen adsorption BET 6-point method by the gas flow method was used.

<Tap density>
The carbon material of the present invention was dropped into a cylindrical tap cell having a diameter of 1.6 cm and a volume capacity of 20 cm ³ using a powder density measuring instrument through a sieve having an opening of 300 μm and filled into the cell, and then the stroke length was 10 mm. Was defined as the density obtained from the volume at that time and the mass of the sample.

Example 1
The scaly natural graphite having a d50 of 100 μm was pulverized by a dry airflow pulverizer to obtain scaly natural graphite having a d50 of 6 μm and a Tap of 0.13 g / cm ³ . Paraffinic oil (liquid paraffin, manufactured by Wako Pure Chemical Industries, Ltd., first grade, physical properties at 25 ° C .: viscosity = 95 cP, contact angle = 13.2 °, surface tension = 31 to 100 g of the obtained scaly natural graphite .7mN / m
, Rcоsθ = 30.9) and stirring and mixing, the obtained sample was pulverized and mixed at a rotation speed of 3000 rpm with a hammer mill (MF10, manufactured by IKA), and a scaly powder uniformly attached with a granulating agent. A natural graphite was obtained. The scale-like natural graphite to which the obtained granulating agent is uniformly attached is attached to the scale-like natural graphite with a hybridization system NHS-1 manufactured by Nara Machinery Co., Ltd. And spheroidizing by mechanical action for 10 minutes at a rotor peripheral speed of 85 m / sec while being encapsulated in spheroidized particles, d50 is 9.2 μm, Tap density is 0.71 g / cm ³ , PD is Spherical graphite having a pore volume of 0.09 μm, PD / d50 of 0.99, and a pore volume in the range of 0.01 μm to 1 μm was 0.16 ml / g. The resulting spheroidized graphite powder and an amorphous carbon precursor mixed with coal tar pitch having a residual carbon ratio of 40% and a density of 1.2 g / cm ³ while being heated to a temperature above the softening point are mixed in an inert gas. After the heat treatment at 1300 ° C., the fired product was crushed and classified to obtain a multilayered carbon material in which graphite particles and amorphous carbon were combined. From the firing yield, the mass ratio of spheroidized graphite particles and amorphous carbon (spheroidized graphite particles: amorphous carbon) in the obtained multilayer carbon material is 1: 0.07. Was confirmed. D50, SA, Tap density, average value of microscopic Raman R value, σ _R , Raman R ₁₅ value, discharge capacity, and low-temperature output characteristics were measured by the above measurement methods. The results are shown in Tables 1 and 2.

(Example 2)
The flaky natural graphite having a d50 of 100 μm was pulverized by a dry swirling pulverizer to obtain a flaky natural graphite having a d50 of 9 μm and a Tap of 0.42 g / cm ³ . Paraffinic oil (liquid paraffin, manufactured by Wako Pure Chemical Industries, first grade) as a granulating agent to 100 g of the obtained scaly natural graphite
Physical properties at 25 ° C .: Viscosity = 95 cP, contact angle = 13.2 °, surface tension = 31.7 mN /
m, rc ｒsθ = 30.9) was added and stirred and mixed, and then the obtained sample was pulverized and mixed at a rotation speed of 3000 rpm with a hammer mill (MF10 manufactured by IKA), and the granulating agent was uniformly attached. Scaly natural graphite was obtained. The scale-like natural graphite to which the obtained granulating agent was uniformly attached is attached to the scale-like natural graphite with a hybridization system NHS-1 manufactured by Nara Machinery Co., Ltd. And spheroidizing by mechanical action for 10 minutes at a rotor peripheral speed of 85 m / sec while being encapsulated in spherical particles, d50 is 12.7 μm, Tap density is 0.87 g / cm ³ , PD is Spherical graphite having a pore volume of 0.09 μm, PD / d50 of 0.71, and a pore volume in the range of 0.01 μm to 1 μm was 0.16 ml / g. The resulting spheroidized graphite powder and an amorphous carbon precursor mixed with coal tar pitch having a residual carbon ratio of 40% and a density of 1.2 g / cm ³ while being heated to a temperature above the softening point are mixed in an inert gas. After the heat treatment at 1300 ° C., the fired product was crushed and classified to obtain a multilayered carbon material in which graphite particles and amorphous carbon were combined. From the firing yield, the mass ratio of spheroidized graphite particles and amorphous carbon (spheroidized graphite particles: amorphous carbon) in the obtained multilayer carbon material is 1: 0.08. Was confirmed. Table 1 shows the results of the same measurement as in Example 1.

Example 3
A multilayer carbon material was obtained in the same manner as in Example 2 except that coal tar having a residual carbon ratio of 28% and a density of 1.2 g / cm ³ was used as the amorphous carbon precursor. From the firing yield, the mass ratio of spheroidized graphite particles and amorphous carbon (spheroidized graphite particles: amorphous carbon) in the obtained multilayer carbon material is 1: 0.08. Was confirmed. Table 1 shows the results of the same measurement as in Example 1.

(Comparative Example 1)
The scaly natural graphite having a d50 of 100 μm was spheroidized by a mechanical action for 10 minutes at a rotor peripheral speed of 85 m / sec using a hybridization system NHS-1 manufactured by Nara Machinery Co., Ltd. In the obtained sample, it was confirmed that a lot of flaky graphite adhering to the base material and not encapsulated and flaky graphite-like fine powder generated during the spheronization treatment were present. This sample was classified to remove the above scale graphite fine powder, d50 was 10.8 μm, Tap density was 0.88 g / cm ³ , PD was 0.36 μm, PD / d50 was 3.27, 0.01 μm or more and 1 μm or less. Spherical graphite having a pore volume in the range of 0.14 ml / g was obtained.

The obtained spheroidized graphite powder and a coal tar having a residual carbon ratio of 28% and a density of 1.2 g / cm ³ as an amorphous carbon precursor were mixed while being heated to a temperature above the softening point, and then in an inert gas. After heat treatment at 1300 ° C., the fired product was crushed and classified to obtain a multi-layer structure carbon material in which graphite particles and amorphous carbon were combined. From the firing yield, the mass ratio of spheroidized graphite particles and amorphous carbon (spheroidized graphite particles: amorphous carbon) in the obtained multilayer carbon material is 1: 0.07. Was confirmed. Table 1 shows the results of the same measurement as in Example 1.

(Comparative Example 2)
A multi-layered carbon material was obtained in the same manner as in Comparative Example 1 except that a coal tar pitch having a residual carbon ratio of 40% and a density of 1.2 g / cm ³ was used as the amorphous carbon precursor. From the firing yield, the mass ratio of spheroidized graphite particles and amorphous carbon (spheroidized graphite particles: amorphous carbon) in the obtained multilayer carbon material is 1: 0.07. Was confirmed. Table 1 shows the results of the same measurement as in Example 1.

Example 4
The flaky natural graphite having a d50 of 100 μm was pulverized by a mechanical pulverizer having a pulverizing rotor and a liner to obtain a flaky natural graphite having a d50 of 30 μm. Obtained scaly natural graphite 10
0 g of paraffinic oil (liquid paraffin, manufactured by Wako Pure Chemical Industries, grade 1, physical properties at 25 ° C .: viscosity = 95 cP, contact angle = 13.2 °, surface tension = 31.7 mN / m
, Rcоsθ = 30.9) was added and stirred and mixed, and then the obtained sample was pulverized and mixed with a hammer mill (MF10 manufactured by IKA Corporation) at a rotational speed of 3000 rpm, and the scale pieces uniformly attached with the granulating agent. A natural graphite was obtained. The obtained flaky natural graphite uniformly attached with the granulating agent is adhered to the base material by the fine powder produced during the spheroidizing treatment with the hybridization system NHS-1 manufactured by Nara Machinery Co., Ltd. While being encapsulated, a spheroidizing process is performed by mechanical action for 10 minutes at a rotor peripheral speed of 85 m / sec. D50 is 16.3 μm, Tap density is 1.03 g / cm ³ , PD is 0.22 μm, Spherical natural graphite having a pore volume in the range of 1.33, 0.01 μm or more and 1 μm or less and 0.10 ml / g was obtained. The resulting spheroidized graphite powder and an amorphous carbon precursor mixed with coal tar pitch having a residual carbon ratio of 40% and a density of 1.2 g / cm ³ while being heated to a temperature above the softening point are mixed in an inert gas. After the heat treatment at 1300 ° C., the fired product was crushed and classified to obtain a multilayered carbon material in which graphite particles and amorphous carbon were combined. From the firing yield, the mass ratio of spheroidized graphite particles and amorphous carbon (spheroidized graphite particles: amorphous carbon) in the obtained multilayer carbon material is 1: 0.04. Was confirmed. Table 1 shows the results of the same measurement as in Example 1.

(Example 5)
A multilayer carbon material was obtained in the same manner as in Example 5 except that coal tar having a residual carbon ratio of 28% and a density of 1.2 g / cm ³ was used as the amorphous carbon precursor. From the firing yield, the mass ratio of spheroidized graphite particles and amorphous carbon (spheroidized graphite particles: amorphous carbon) in the obtained multilayer carbon material is 1: 0.04. Was confirmed. Table 1 shows the results of the same measurement as in Example 1.

(Comparative Example 3)
The scaly natural graphite having a d50 of 100 μm was spheroidized by a mechanical action for 3 minutes at a rotor peripheral speed of 85 m / sec using a hybridization system NHS-1 manufactured by Nara Machinery Co., Ltd. In the obtained sample, it was confirmed that a lot of flaky graphite adhering to the base material and not encapsulated and flaky graphite-like fine powder generated during the spheronization treatment were present. The sample is classified to remove the graphite flake fine powder, and d50 is 15.7 μm, Tap density is 1.02 g / cm ³ , PD is 0.36 μm, PD / d50 is 2.31, 0.01 μm to 1 μm. Spherical graphite having a pore volume in the range of 0.13 ml / g was obtained. The obtained spheroidized graphite powder and a heavy petroleum oil having a residual carbon ratio of 18% and a density of 1.1 g / cm ³ as an amorphous carbon precursor are mixed while being heated to a temperature above the softening point, and inert. After heat treatment in gas at 1300 ° C., the fired product was crushed and classified to obtain a multilayered carbon material in which graphite particles and amorphous carbon were combined. From the firing yield, the mass ratio of spheroidized graphite particles and amorphous carbon (spheroidized graphite particles: amorphous carbon) in the obtained multilayer carbon material is 1: 0.04. Was confirmed. Table 1 shows the results of the same measurement as in Example 1.

In Examples 1 to 5, the standard deviation (σ _R ) of the micro Raman R value is within the specified range by adding and mixing an appropriate amount of a specific carbonaceous material precursor to a carbon material having a specific intraparticle pore. Therefore, it showed excellent low-temperature input / output characteristics. In Examples 1 to 3, since the ratio in which the R value is 0.15 or less is a preferable range, particularly excellent low-temperature input / output characteristics were exhibited. On the other hand, in Comparative Examples 1 to 3 in which σ _R is out of the specified range, it was confirmed that the low-temperature input / output characteristics were deteriorated.

  The carbon material of the present invention can provide a nonaqueous secondary battery having excellent input / output characteristics by using it as an active material for a nonaqueous secondary battery negative electrode. Moreover, according to the manufacturing method of the said material, since there are few processes, it can manufacture stably and efficiently and cheaply.

Claims (10)

A composite carbon material containing a carbonaceous material (B) on the surface of a carbon material (A) capable of occluding and releasing lithium ions, and a micro Raman R value of 30 randomly selected composite carbon materials. A composite carbon material for a non-aqueous secondary battery, wherein the average value is 0.1 or more and 0.85 or less, and the standard deviation (σ _R ) is 0.1 or less. 2. The composite carbon material for a non-aqueous secondary battery according to claim 1, wherein a micro Raman R ₁₅ value represented by the following formula (1) is 12% or less.
Microscopic Raman R ₍₁₅₎ value (%) = number of composite carbon materials that are 0.15 or less of microscopic Raman R values of 30 randomly selected composite carbon materials / 30 × 100 (1) According to claim 1 or 2 for nonaqueous secondary batteries composite carbon material according to, wherein the tap density of the composite carbon material is less than 0.6 g / cm ³ or more 1.20 g / cm ^3. 4. The composite carbon material for a non-aqueous secondary battery according to claim 1, wherein the composite carbon material has a specific surface area (SA) of 1 m ² / g or more and 30 m ² / g or less. . The carbon material is graphite obtained by spheroidizing at least one carbon material selected from the group consisting of scaly natural graphite, scaly natural graphite, and massive natural graphite. The composite carbon material for nonaqueous secondary batteries according to Item 1. The pore volume in the range of 0.01 μm or more and 1 μm or less is 0.07 mL / g or more, and the ratio of the pore diameter to the particle diameter (PD / d50 (%)) represented by the following formula (2) is 1.8. A carbon material and a carbonaceous material precursor, which are the following, are mixed at a temperature equal to or higher than the softening point of the carbonaceous material precursor, and then the carbonaceous material precursor is carbonized by heat treatment. Material manufacturing method.
PD / d50 (%) = mode pore diameter (PD) / volume-based average particle diameter (d50) × 100 in the range of 0.01 μm or more and 1 μm or less in the pore distribution determined by the mercury intrusion method (2) The non-aqueous system according to claim 6, wherein the carbon material is graphite obtained by spheroidizing at least one carbon material selected from the group consisting of scaly natural graphite, scaly natural graphite, and massive natural graphite. A method for producing a composite carbon material for a secondary battery. The method for producing a composite carbon material for a non-aqueous secondary battery according to claim 6 or 7, wherein a softening point of the carbonaceous material precursor is 400 ° C or lower.
The composite carbon material for non-aqueous secondary batteries manufactured by the manufacturing method of the composite carbon material for non-aqueous secondary batteries of any one of Claims 6-8. A positive electrode and a negative electrode capable of inserting and extracting lithium ions, and an electrolyte, the negative electrode includes a current collector and a negative electrode active material layer formed on the current collector, and the negative electrode active material layer includes A non-aqueous secondary battery comprising the composite carbon material according to claim 1.