JPH08104510A - Production of carbon based composite material - Google Patents

Abstract

PURPOSE: To produce a carbon based composite material uniform and good in performance and suitable to an electrode material for nonaqueous solvent secondary cell by treating carbonaceous particles having a specified physical property with heavy oil, then, heat-treating its treated matter in an inactive atmosphere. CONSTITUTION: This material is obtained by following A and B stage. (A) The carbonaceous particles whose d002 is <=0.345nm and Lc is >=15nm, preferably >=50nm are dispersed in the heavy oil and is brought into contact with the heavy oil to make a polycyclic arom. molecule or oligomer impregnated and adsorbed on a surface of the carbonaceous particles and in fine pores. (B) A thermochemical reaction such as polycondensation of the polycyclic arom. component impregnated on the surface of the carbonaceous particles and in the fine pores is allowed to proceed by heat-treating a product of the A stage in the inactive atmosphere. A solid-liq. separation stage is provided after the A stage and a powder processing stage is provided after the B stage at need. This composite material has <=30m<2> BET method specific surface area and <=35μm volume average grain size.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a carbon composite material, and more particularly to a method for producing a carbon composite material suitable as an electrode material for a non-aqueous solvent secondary battery.

[0002]

2. Description of the Related Art In recent years, with the miniaturization of electronic equipment, a high capacity secondary battery has become necessary. In particular, non-aqueous solvent secondary batteries, which have higher energy density than nickel-cadmium and nickel-hydrogen batteries, have been receiving attention. Metals and graphite have been studied as the negative electrode material. However, the metal electrode has a problem that when the charge and discharge are repeated, the metal in the solvent is deposited in the form of dendrite, and eventually both electrodes are short-circuited. In addition, graphite has no problem of short-circuiting because metal ions can enter and leave between the layers, but it decomposes the propylene carbonate-based electrolytic solution, and the problem that the charge / discharge cycle characteristics are poor in the ethylene carbonate-based electrolytic solution. There is.

On the other hand, the use of a carbonaceous material (carbon-based composite material) having a multiphase structure, as disclosed in, for example, Japanese Patent Application Laid-Open No. 4-171677, has been studied. this is,
Advantages (high capacity and small irreversible capacity) and disadvantages (decomposes propylene carbonate-based electrolytic solution) of carbonaceous matter with high crystallinity and advantages (excellent stability with electrolytic solution) and disadvantages of carbonaceous matter with low crystallinity It is based on the idea of combining (small capacity and large irreversible capacity) to make up for each other's strengths while compensating for their weaknesses.

A method for producing such a carbon-based composite material is disclosed in, for example, the above-mentioned Japanese Patent Laid-Open No. 4-171677.
(1) Heat treatment of a mixture of 1 micron graphite particles and petroleum-based binder pitch to convert the binder pitch to coke or partially graphitized carbon. (2) Drop of liquefied coke in a furnace. Each injection method is described.

[0005]

However, in the method (1), it is difficult to highly fill the graphite because the binder pitch is highly viscous, and the graphite content in the graphite composite obtained as a result of the heat treatment is increased. Is limited, and the high charge / discharge capacity of graphite cannot be fully utilized. Furthermore, it is relatively difficult to obtain a homogeneous mixture on an industrial scale because the viscosity of the mixture is extremely high. In addition, in this method, after the mixing process is completed, the process moves to the heat treatment process,
Continuous industrial production is difficult.

The spherical coke obtained by the method (2) includes, for example, "carbon material engineering" (published by Nikkan Kogyo Shimbun).
As described by Michio Inagaki) and the like, two types of particles that are greatly different in appearance and internal structure are mixed. Therefore, when the spherical coke obtained by this method is used for an electrode, it is difficult to make the composition and particle size of the particles uniform, the electrode moldability is extremely poor, and the specific surface area is small, so that a high capacity cannot be obtained. There is a problem.

[0007]

In order to solve the above-mentioned object, the present inventors formed a carbonaceous material (S) as a surface phase on the surface of carbonaceous material particles (N) forming nuclei, and finally, As a result of repeated intensive studies on a method for producing a carbon-based composite material having a multi-phase structure, a carbonaceous material particle (N) is obtained by depositing a heavy oil component on the surface of the carbonaceous material particle and then polycondensing it. The high-performance composite carbonaceous material particles of extremely good quality, in which the carbonaceous material (S) is also filled in the pores of and the surface of the thinned carbonaceous material (S) is uniformly coated, can be stably and efficiently produced. As a result, they have completed the present invention.

That is, the present invention is based on d in X-ray diffraction.
Of carbonaceous material particles having 002 of 0.345 nm or less
Or part of it, d002 is larger than 0.345
Carbon-based composite material with multi-phase structure compounded with coated carbon material
The true density is 1.80 g / cm³That is the BET method
Specific surface area is 30m²/ G or less, volume-based average particle size is 35
Argon ions with a wavelength of 514.5 nm or less
In Raman spectrum analysis using laser light, 1
580 cm^-1Peak P near_A, 1360 cm^-1With
Near peak P _BAnd has the above P_AStrength I_AP for
_BStrength I_BRatio R (= I_A/ I_B) The value is the core charcoal
The upper limit is the R value of the elementary particles, and more preferably the R value is
A method for producing a carbon-based composite material, which is 0.3 or more,
At least (A) d002 is 0.345 nm or less and Lc is 15 n
m or more, preferably 50 nm or more carbonaceous material particles
Polycyclic aromatics contained in heavy oil dispersed in oil and contacted
Molecules or oligomers on the surface and pores of carbonaceous material particles
First step of impregnating and adsorbing in (B) First step Heat treatment of the product under an inert atmosphere
Polycyclic aromatic compounds impregnated on the surface and pores of elementary particles
The production method is composed of a second step of advancing a thermochemical reaction such as polycondensation.

The present invention will be described in detail below. (1) Adjustment and Selection of Mixed Raw Material (a) Carbonaceous Material (N) In the carbon-based composite material produced by the present invention, the particulate carbonaceous material (N) that finally forms a nucleus has a volume average particle diameter of 30 μm or less, d ₀₀₂ is 0.345 nm or less, and Lc is 15 nm or more, and preferably d ₀₀₂ is 0.34.
5 nm or less and Lc of 50 nm or more, more preferably
It is a carbonaceous material having d ₀₀₂ of 0.345 nm or less and Lc of 80 nm or more. Specifically, it is also possible to use graphite-based particles, as well as pitch-based, polyacrytonitrile (PAN) -based, mesophase-pitch-based, and vapor-phase-grown graphite carbon fibers processed into powder form. Also,
You may use these 2 or more types in mixture.

The carbonaceous material (N) is 1. Melt-soluble organic matter, thermosetting polymer, etc. in an inert gas atmosphere or in vacuum at 1500 to 3000 ° C.,
A method of carbonizing and graphitizing by preferably heating at a temperature of 2000 to 3000 ° C. 2. A method in which a ready-made carbonaceous material such as carbon black or coke is further heat-treated to appropriately promote graphitization. 3. A method in which artificial graphite, natural graphite, vapor-grown graphite whiskers, and carbon fiber are adjusted in particle size or fiber length as necessary, and then powdered. Etc. can be obtained.

Here, 1. The organic compound, which is the raw material, can be classified into a raw material that passes through a liquid phase and a raw material that carbonizes in the solid phase when an organic substance is converted into a solid-phase carbon body. Examples of the liquid-phase carbonization raw material include aromatic hydrocarbons such as acenaphthylene and naphthalene, hot-melt polymers such as polyvinyl chloride, and heavy oils such as coal tar pitch and ethylene tar pitch. On the other hand, as the solid-phase carbonization raw material, natural polymers such as cellulose, thermosetting resins such as phenol-formaldehyde resin, thermoplastic polymers such as polyamide and polyacrylonitrile, and polyvinyl chloride that has been infusibilized by air oxidation pretreatment. , And melt-soluble organic substances such as pitch.

(B) Carbonaceous Material (S) On the other hand, in the carbon-based composite material produced by the present invention, the carbonaceous material (S) that finally forms the surface phase is d _002.
Is 0.340 nm or more and 0.400 nm or less, preferably 0.342 nm or more and 0.370 nm or less, and more preferably 0.345 nm or more and 0.365 nm or less. Lc is 30 nm or less, preferably 10 nm or less,
The carbonaceous material is more preferably 6 nm or less, and most preferably 4 nm or less. As a raw material for such a carbonaceous material, heavy oil in a liquid state having a predetermined viscosity or less can be used. As for the viscosity, the viscosity at 50 ° C is 2
It is preferably 00 cp or less, more preferably 80 cp or less.

If the viscosity exceeds 200 cp, the heavy oil cannot be sufficiently separated in the step of separating the carbonaceous material particles and the excess heavy oil, and a uniform composite carbon material cannot be obtained. When a heavy oil having a viscosity of more than 200 cp at 50 ° C. is used, it can be prepared by diluting it with a solvent composed of an aromatic system such as toluene or quinoline or a heterocyclic compound and preparing it at 200 cp or less.

As the heavy oil that can be used in the present invention, for example, as described in "Chemical and Engineering of Carbon Materials" (Asakura Shoten Isao Mochida), coal tar from soft pitch to hard pitch. Heavy coal oil such as pitch and dry-distilled liquefied oil, direct-current heavy oil such as atmospheric residual oil and vacuum residual oil, cracked heavy oil such as ethylene tar produced by thermal decomposition of crude oil, naphtha, etc. There is a heavy petroleum oil. Among these heavy oils, ethylene heavy end tar generated especially during naphtha decomposition has a viscosity of about 70 cp at 50 ° C. and contains 3% or more of polycyclic aromatic molecules having a weight average molecular weight of 3000 to 4000, Suitable for practicing the present invention.

(2) First step: mixing / impregnation / substitution step In the first step of the present invention, carbonaceous material particles (carbonaceous matter (N)) are mixed with heavy oil (raw material for carbonaceous matter (S)). A step of substituting the polycyclic aromatic molecule contained in the heavy oil, preferably a polycyclic aromatic oligomer having a larger molecular weight, to disperse the particle surface and the inside of the pores by dispersing and sufficiently contacting with the heavy oil. .

If the carbonaceous material particles are subjected to a solvent treatment in advance before this step, better results can be obtained. That is, by immersing in a solvent composed of an aromatic system or a heterocyclic compound, after replacing the surface and pores with the solvent, by using the carbonaceous material particles separated from the excess solvent, to the heavy oil of the carbonaceous material particles "Wet" is improved to ensure contact between the heavy oil and the carbonaceous material particles, and to improve the dispersion of the carbonaceous material particles in the heavy oil. In addition, since a good solvent for the polycyclic aromatic molecule is used, the probability that the polycyclic aromatic molecule in the heavy oil will contact the carbonaceous material particle surface is increased. As a result, there is an effect that the adsorption efficiency of the polycyclic aromatic molecule contained in the heavy oil on the surface of the carbonaceous material particles is improved. As the solvent composed of an aromatic or heterocyclic compound used for this solvent treatment, a solvent in which the polycyclic aromatic molecule contained in the heavy oil is easily dissolved is preferable. Specifically, quinoline or pyridine can be used as the solvent composed of the heterocyclic compound, and toluene or benzene can be used as the aromatic solvent.

This step may be carried out by either a batch type mixer or a continuous type mixer. In addition, the reaction tank may or may not be heated, but heating the reaction tank lowers the viscosity of the mixture, reduces the load on the device, and
It is preferable because it enhances the impregnation / substitution effect. Further, by reducing the pressure in the tank during mixing, the effect of defoaming from the fine powder is enhanced, the air entrapped on the surface of the carbonaceous material particles and in the pores is removed, and the substitution and adsorption by the solvent is further improved. Can be complete.

When a batch type mixer is used, one mixer having a stirring blade may be used as the apparatus, or a plurality of mixers may be used to successively improve the dispersity and the contact degree. The mixer can select various types and types of devices depending on the viscosity of the mixture. That is, a device such as a dissolver that is a high-speed high-shear mixer and a blade mixer such as a butterfly mixer for high viscosity that stirs and disperses the inside of the tank, a sigma type or the like along the side surface of the semi-cylindrical mixing tank. A so-called kneader type device having a structure in which a stirring blade rotates, a device having a structure in which two frame type blades rotate while performing a planetary motion in a fixed tank, and the stirring blades of this device have a total of three axes. Such a trimix type device, a so-called bead mill type device having a rotating disk and a dispersion medium in a dispersion tank can be used.

Among these devices, a mixer having a structure in which two frame-type blades rotate while performing planetary motion in a fixed tank is preferable in that the applicable viscosity range of the slurry is wide. A mixer having such a structure is commercially available, for example, from Inoue Seisakusho under the name of a planetary mixer.

On the other hand, when a continuous mixer is used, a pipeline mixer may be used, or a continuous bead mill (medium disperser) may be used. When a continuous mixer is used, the reaction raw materials can be conveyed to the second step at the same time while the first step is performed, and more efficient production can be realized.

(3) Second Step: Solid-Liquid Separation Step In this step, the surface and pores obtained in the first step are sufficiently impregnated with polycyclic aromatic molecules, and the carbonaceous material particles adsorbed are excessively weighted. This is a step of separating the oil from the oil by filtration. In this separation step, a general method for solid-liquid separation such as a filtration method using a filter press or a pressure filter or a centrifugal separation method can be used. Note that this step can be omitted depending on the amount and viscosity of the volatile component of the heavy oil.

(4) Third Step: Carbonization Step In this step, carbonaceous material particles having the polycyclic aromatic molecule obtained in the second step adsorbed on the surface and in the pores are heated to advance carbonization. It is the process of making. Carbonization is performed by heating the carbonaceous material particles from the second step under a flow of an inert gas such as nitrogen gas, carbon dioxide gas, argon gas. In the carbonization in this step, first, the volatile components of the heavy oil component evaporate, and then the residual components including polycyclic aromatic molecules proceed thermochemical reaction,
Polycondensation is allowed to proceed on the surface of the carbonaceous material particles and in the pores. As the polycondensation progresses, oxygen, nitrogen, and hydrogen are discharged out of the system, structural defects existing in the polycondensate are removed depending on the degree of heat treatment, and the carbon precursor and carbon are sequentially changed.

The lower limit of the heating temperature in this step is usually 500 ° C. or higher, preferably 600 ° C. or higher, more preferably 700 ° C. or higher, though it varies slightly depending on the type of heavy oil and its heat history. On the other hand, the upper limit temperature does not have a structural order that exceeds the crystal structure of the carbonaceous material (N) whose residue is the heavy oil,
That is, it can be determined within a range having a lower degree of graphitization than the carbonaceous material (N). Therefore, the upper limit temperature of the heat treatment is usually 2500 ° C. or lower, preferably 2000 ° C. or lower, and more preferably 1500 ° C. or lower. Under such heat treatment conditions, the temperature rising rate, the cooling rate, the heat treatment time, etc. can be arbitrarily set according to the purpose. In addition, after heat treatment in a relatively low temperature region, the temperature can be raised to a predetermined temperature.

The reactor used in the third step may be a batch heating furnace or a continuous heating furnace, and may have a single reactor or a plurality of reactors connected to each other. Further, the product of the second step to be charged into the reactor is subjected to necessary pretreatment depending on the type of the reactor, that is, processing of the shape, specifically, crushing, crushing or further adjusting the particle size with granulation. You can go.

(5) Fourth step: powder processing step In the third step, the residue of the heavy oil is carbonized, and a product is obtained by complexing the surface of the carbonaceous material particles, which is the core, partially or entirely. In the fourth step, powder processing such as pulverization, crushing, and classification treatment is performed as necessary to obtain a non-aqueous solvent secondary battery electrode material. In batteries, it is necessary to fill as much electrode material as possible into a given volume. Since the negative electrode material is used by applying it to a metal foil as a current collector and rolling it into a sheet electrode, it is preferable that the negative electrode material has a particle diameter of a certain value or less. Specifically, the volume average particle size is 1
μm or more and 45 μm or less, preferably 1 μm or more and 35 μm
The thickness is more preferably 1 μm or more and 25 μm or less, and particularly preferably 1 μm or more and 15 μm or less. The powder processing step may be inserted between the second and third steps as the case may be, as described above.

As a result of passing through the first to fourth steps, 1. BET specific surface area of 30 m ² or less, Volume-based average particle diameter is 35 μm or less, ^{3. The} true density is 1.80 g / cm ³ or more, 4. Derived from carbonaceous material (N) by X-ray diffraction measurement, (00
2) The surface spacing d ₀₀₂ is 0.345 nm or less, and Lc is 15
nm or more, and d ₀₀₂ derived from the carbonaceous material (S) is 0.
4. Larger than 345 nm. Peak P _A around 1580 cm ^-1 by Raman spectrum analysis using an argon ion laser beam having a wavelength of 514.5 nm, the ratio _{R (= I A / I B} ) value of the peak intensity of a peak P _B in the vicinity of 1360 cm ^-1 is, It is possible to obtain a carbon-based composite material which is larger than the R value of the carbonaceous material (N) alone, and more preferably 0.3 or more, which is suitable as an electrode material for a non-aqueous solvent secondary battery.

[0027]

The present invention will be described in more detail with reference to Examples. In the following examples and comparative examples, each parameter was measured as follows. (A) Interplanar spacing (d ₀₀₂ ) of (002) plane, crystallite size LC If the carbonaceous material is a powder, it is pulverized as it is in an agate mortar if it is in the form of small pieces, and it is approx. 15 wt%
The X-ray standard high-purity silicon powder of 1 was added and mixed, packed in a sample cell, and a wide-angle X-ray diffraction curve was measured by a reflection diffractometer method using CuKα rays monochromatized with a graphite monochromator as a radiation source. Since the carbon-based composite material according to the production method of the present invention is composed of carbonaceous material (N) and carbonaceous material (S) having different graphitization degrees, the X-ray diffraction curve has two peaks derived from different crystallinity. It has overlapping shapes. Specifically, the low-angle side has a relatively broad peak derived from the carbonaceous material (S) that is the coating phase, and the high-angle side has a relatively sharp peak derived from the carbonaceous material (N) constituting the nucleus. are doing. After separating peaks from this diffraction curve, d ₀₀₂ and Lc were calculated for each peak.

(B) Raman spectrum analysis: wavelength 51
In Raman spectrum analysis using an argon ion laser beam of 4.5 nm, the intensity I _A of the peak P _A in the vicinity of 1580 cm ^-1, a peak P _B in the vicinity of 1360 cm ^-1
The intensity I _B were measured, and measurement results of the specific R = I _B / I _A of the intensity.

(C) True Density Using a pycnometer, it was measured by a gas replacement method with helium gas. (D) Specific surface area Using the specific surface area, it was measured by the BET one-point method by nitrogen gas adsorption. (E) Volume-based average particle diameter Using a laser diffraction particle size distribution meter, ethanol was used as the dispersion medium to measure the volume-based average particle diameter (median diameter).

Example 1 (1) First Step As a carbonaceous material (N), artificial graphite powder (KS-44 manufactured by LONZA: d ₀₀₂ = 0.336 m, Lc = 100 nm or more, average volume particle size 19 μm). 5 kg, 30 kg of ethylene heavy end tar (manufactured by Mitsubishi Petrochemical Co., Ltd .: viscosity of 50 cp at 50 ° C.) as a heavy oil was put into a 50 liter mixing tank, and a DHC-P-005 portable dissolver manufactured by Inoue Seisakusho Co., Ltd. And stirred at 1200 rpm.

Mixing was carried out for 30 minutes from the start of stirring while heating the mixing tank so that the liquid temperature became 50 ° C. After 30 minutes, the mixed solution became a very smooth slurry, and almost all the charged amount was recovered. When the degree of dispersion of the slurry was examined by a grind gauge, a locus that was almost the same as the maximum particle size of the primary particles of the artificial graphite powder was obtained.

(2) Second Step The slurry obtained in the first step was filtered under reduced pressure. The filtered product was in the form of a dry cake and could be crushed into a powder when picked up by hand. This powder had no metallic luster of the carbonaceous material (N) before mixing, and was a brown powder.

(3) Third Step The cake made of the composite powder of carbonaceous material (N) and the residue of heavy oil obtained in the second step was heat-treated in a batch heating furnace. The cake was placed in a graphite container and placed in an internal heating furnace, the temperature was raised to 1100 ° C over 2 hours and 30 minutes under a flow rate of nitrogen gas of 5 l / min, and then the temperature was raised to 1200 ° C over 30 minutes. Warmed and held at 1200 ° C for 1 hour.
Then, it was naturally cooled to room temperature to obtain a heat-treated product in which the residue of heavy oil was carbonized. The heat-treated product retained the shape of the cake before the heat treatment in the graphite container, but it could be easily crushed when taken by hand.

(4) Powder Treatment Step The heat-treated product, which was a composite of carbonaceous material particles and carbonaceous coating phase, had some fusion between the particles, so a roll crusher was used. The particles were crushed into primary particles to obtain a carbon-based composite material powder having an average volume particle size of 21 μm.

(5) Analysis of carbon-based composite material powder The analysis results were as follows. Wide-angle X-ray diffraction analysis: d ₀₀₂ = calculated from the low-angle peak
0.346 nm LC = 3.3 nm d ₀₀₂ = 0.336 nm calculated from the high-angle side peak = 100 nm or more Raman spectrum: R = 0.48 Since the R value of the carbonaceous material (N) is 0.1, this From the measurement results, it can be seen that the surface is covered with the carbonaceous material (S) having a low carbonization degree. True density: 2.20 g / cm ³ Specific surface area: 3.5 m ² / g Average volume particle size: 21 μm

(6) Evaluation of Electrode Performance (6-1) Preparation of Electrode Molded Body 93% by weight of the carbon-based composite material obtained in Example 1 of thermoplastic elastomer (styrene / ethylene / butylene / styrene / block copolymer) Toluene solution 4% by weight
(Solid content) and 3% by weight of polyethylene powder were added and stirred to obtain a slurry. This slurry was applied on a copper foil and pre-dried at 80 ° C. After further crimping it to the copper foil, punch it out on a disk with a diameter of 20 mm, 110 ° C
It was dried under reduced pressure to obtain an electrode.

(6-2) Electrode Evaluation by Half-Battery A separator (polyethylene porous film) impregnated with an electrolytic solution is sandwiched between the above electrodes to prepare a coin-shaped cell facing a lithium metal electrode and charged. A discharge test was conducted. The electrolyte used was a solvent in which ethylene carbonate and diethyl carbonate were mixed at a weight ratio of 1: 1 and lithium perchlorate was dissolved at a ratio of 1.5 mol / liter.

In the charge / discharge test, the current value was 1.54 mA,
Charge until the potential difference between both electrodes becomes 0V, then 1.5
Discharged to V. As a result, the charging capacity is 255 mA
The h / g and discharge capacity were 253 mAh / g. The charge / discharge efficiency was calculated to be 99% from each capacity.

Example 2 (1) First Step As a carbonaceous material (N), artificial graphite powder (KS-44 manufactured by LONZA: d ₀₀₂ = 0.336 m, Lc = 100 nm or more, average volume particle size 19 μm). 5 kg, coal tar pitch as heavy oil (Kawasaki Steel Co., Ltd. PKQL: 50
Experiments were carried out with 10 kg (solid at ° C). Since this coal tar pitch had a quinoline insoluble content of 0.01% or less, it was diluted to 30 cp with quinoline before use. Using a DHC-P-005 portable dissolver manufactured by Inoue Manufacturing Co., Ltd.
Stirred at 0 rpm. The mixing was performed at room temperature and was performed for 30 minutes from the start of stirring. After 30 minutes, the mixed solution became a slurry, and almost all the charged amount was recovered. When the degree of dispersion of the slurry was examined by a grind gauge, a locus that was almost the same as the maximum particle size of the primary particles of the artificial graphite powder was obtained.

(2) Second to Fourth Steps The composite material thus obtained is subjected to solid-liquid separation treatment in the same manner as in Example 1, followed by heat treatment at 1200 ° C., and then powder processing treatment to obtain a carbonaceous material. A composite material was obtained.

(3) Analysis of carbon composite material The analysis results were as follows. Wide-angle X-ray diffraction analysis: d ₀₀₂ = calculated from the low-angle peak
0.348 nm LC = 3.3 nm d ₀₀₂ = 0.336 nm calculated from the high-angle side peak = 100 nm or more Raman spectrum: R = 0.47 Since the R value of the carbonaceous material (N) is 0.1, this From the measurement results, it can be seen that the surface is covered with the carbonaceous material (S) having a low carbonization degree. True density: 2.20 g / cm ³ Specific surface area: 3.6 m ² / g Average volume particle size: 20 μm

(5) Evaluation of Electrode Performance A half battery was manufactured in the same manner as in Example 1 and the charge / discharge characteristics were measured. Charge capacity is 267mAh / g, discharge capacity is 263m
Ah / g and charge / discharge efficiency were 99%.

(Comparative Example 1) A carbonaceous material prepared by a method of converting a pitch binder into coke or partially graphitized carbon by heating a mixture of graphite particles of about 1 micron and petroleum-based binder pitch. An evaluation was made. As such a carbonaceous material, HNOGSI-of Graphite Sales Co. of Changling Falls, Ohio, USA
EC110 (isotropic graphite) was used.

The obtained electrode material was analyzed and the electrode performance was evaluated in the same manner as in Example 1. As a result, peak separation was not possible in wide-angle X-ray diffraction measurement, and d002 was 0.3.
37 nm and Lc were 73 nm. In the Raman spectrum analysis, the R value of the peak was 0.25. Furthermore, the true density was 2.17 g / cm ³ , the specific surface area was 5.2 m ² / g, and the average particle size was 24 μm.

On the other hand, regarding the evaluation results of the electrode performance, the charge capacity was 81 mAh / g, the discharge capacity was 76 mAh / g, and the charge / discharge efficiency was 94%.

(Comparative Example 2) Spherical graphite having a graphitized phase granule obtained by injecting liquefied coke droplets into a furnace and a graphitized phase containing a portion with less graphitization at the grain boundary was evaluated. . An example of such spherical graphite is # 9 manufactured by Shuperiore Graphite of Chicago, Illinois, USA.
400 was used.

Analysis and electrode performance evaluation were performed in the same manner as in Example 1. As a result, peak separation could not be performed by wide-angle X-ray diffraction measurement, and d002 was 0.338 nm and Lc was 29 nm. In the Raman spectrum analysis, the R value of the peak was 0.22. The true density was 1.73 g / cm ³ , and the specific surface area was 0.49 m ² / g. Incidentally, the particles were considerably coarse, and there were particles that were in the measurement range of the laser type particle size distribution meter, and the average particle size could not be calculated. On the other hand, regarding the electrode performance evaluation results performed under the same conditions as in Example 1, the charge capacity and the discharge capacity were 62 mAh /
g, 57 mAh / g, and the charge / discharge efficiency was 92%. In addition, # 9400 had extremely poor electrode moldability, and there were many difficulties in actually using it as an electrode.

Table 1 shows the wide-angle X-ray diffraction measurement results and Table 2 shows the electrode performance evaluation results of Examples 1-2 and Comparative Examples 1-2.

[0049]

[Table 1]

[0050]

[Table 2]

[0051]

As described above, the method for producing a carbon-based composite electrode material of the present invention uses carbonaceous material particles and heavy oil as raw materials, and impregnation treatment, solid-liquid separation treatment, carbonization treatment, and powder processing treatment. A method of producing a high performance carbon-based composite electrode material by combining A uniform composite carbon material can be obtained by performing heat treatment after impregnation up to the point, and a more complete thinning of the coating phase can be achieved. Therefore, according to the present invention, a high-performance carbon material having uniform performance and good quality can be stably and efficiently manufactured.

The carbon-based composite material obtained by the method of the present invention is
It is suitable as an electrode material for a non-aqueous solvent secondary battery, which is stable in an electrolytic solution, has a large electrode capacity, is excellent in charge / discharge cycle characteristics, and is compatible with rapid charge / discharge.

Front page continued (72) Inventor Keiko Sugawara 8-3-1 Chuo, Ami-cho, Inashiki-gun, Ibaraki Mitsubishi Petrochemical Co., Ltd. Tsukuba Research Laboratory (72) Inventor Shoichiro Mori 8-chome, Ami-cho, Inashiki-gun, Ibaraki No. 1 in Mitsubishi Petrochemical Co., Ltd. Tsukuba Research Institute

Claims (4)

[Claims] 1. The d002 in X-ray diffraction is 0.345.
A carbon-based composite material having a multi-phase structure in which all or part of carbonaceous material particles having a particle diameter of nm or less is coated with a coated carbon material having a d002 of greater than 0.345, and a true density of 1.80 g / cm ³ or more. And the BET specific surface area is 30
m ² / g or less, volume-based average particle diameter of 35 μm or less, and 1580 cm ⁻¹ in Raman spectrum analysis using an argon ion laser beam having a wavelength of 514.5 nm.
Peak P _A near the and P peak near 1360 cm ^-1
Has a _B, the strength of P _B with respect to the intensity I _A of the P _A I _B
The ratio _{R (= I A / I B} ) values, the R value of the carbonaceous material particles as a core and an upper limit, and more preferably a method of producing a carbon-based composite material R value is 0.3 or more, At least (A) d002 is 0.345 nm or less and Lc is 15 n
m or more, preferably 50 nm or more carbonaceous material particles are dispersed in heavy oil and brought into contact with each other to impregnate polycyclic aromatic molecules or oligomers contained in the heavy oil on the surface and pores of the carbonaceous material particles, First step of adsorbing (B) The product of the first step is heat-treated in an inert atmosphere, and the polycyclic aromatic component impregnated on the surface and pores of the carbonaceous material particles is subjected to heat such as polycondensation. A method for producing a carbon-based composite material, comprising a second step of advancing a chemical reaction. 2. The method for producing a carbon-based composite material according to claim 1, wherein the second step is performed after separating the product of the first step from excess heavy oil. 3. The method further comprises a third step of crushing or crushing the product of the second step and classifying the product to have a volume average particle size of 35 μm or less to obtain a carbon-based composite powder. The method for producing a carbon-based composite material according to claim 1, wherein 4. The carbonaceous material particles, wherein the surface and the pores of the carbonaceous material particles are previously impregnated with a solvent composed of an aromatic compound or a heterocyclic compound.
A method for producing the carbon-based composite material as described above.