JP5411652B2 - Method for producing lump-dispersed carbon material and method for producing lump-dispersed graphite material - Google Patents

Description

The present invention relates to a method for producing a lump-dispersed carbon material used for, for example, a battery electrode material, and a method for producing a graphite material.

  In recent years, lithium ion secondary batteries have been widely used as batteries for portable electrical products. This lithium-ion secondary battery is expected to have a significant increase in demand as a battery for mobile phones and notebook computers. This is because the lithium ion secondary battery is small and light, has a large charge / discharge capacity, can take out high voltage and large current, has excellent cycle life, is highly safe, has few problems on environmental pollution, etc. This is because it has characteristics.

In general, natural graphite powder having the ability to occlude and desorb lithium ions is used as a negative electrode material for a lithium ion secondary battery. The basic mechanism of occlusion and desorption of lithium ions in graphite is the insertion and desorption of lithium ions between graphite layers. The stoichiometric ratio of Li and C shown by the characteristic formula LiC ₆ Maximum occlusion amount.

  However, in the case of natural graphite, the particle shape is scaly and the particles are easily oriented during electrode production. Therefore, the filling property is very high, but the permeability of the electrolytic solution is lowered. Further, by orientation, the crystallite basal plane becomes parallel to the electrode plate, and charge / discharge characteristics at a large current are deteriorated. For these reasons, it is often performed to produce spherical graphite particles and to produce a close packed electrode. In the case of spherical particles, the particles are closely packed and at the same time, an appropriate space is formed between the particles, and the permeability of the electrolytic solution is ensured. Also, the problem of orientation is solved. However, in the case of spherical particles, the contact between the particles is a point contact, so that contact failure is liable to occur due to the expansion / contraction of the particles due to charge / discharge, and the cycle characteristics are deteriorated.

  In order to overcome such drawbacks, for example, several percent of fibrous carbon such as vapor-grown carbon fiber is added to improve contact between particles (see Patent Document 2). Such conductive aids are expensive and expensive.

JP 09-063584 A JP 2003-160323 A

  Therefore, in view of the above circumstances, an object of the present invention is to provide a technique for providing a carbon material that easily forms a high filling structure, and to improve contact between particles and to improve cycle characteristics, and has a high degree of graphitization. The purpose is to provide a technique for producing graphite material at low cost.

In order to achieve the above object, the present inventors have conceived a method for producing a carbon material in which a molten carbon precursor melted in a heated and flowing state is discharged and cooled from a nozzle to form spherical particles in order to obtain fine carbon particles. . Therefore, when a discharge process is performed in which the molten carbon precursor in a heated and fluidized state is discharged intermittently from the nozzle, the discharged molten carbon precursor is cooled and shaped as a microspherical shaped carbon precursor by surface tension. As a result, we have intensively studied this production method.
However, surprisingly, according to this manufacturing method, the molten carbon precursor becomes an experimentally shaped carbon precursor with various spherical shapes, and is experimentally cooled. Could be revealed.

  Furthermore, the main component of the carbon precursor material produced in this manner has a tadpole-like shape with a head that is a substantially spherical lump and a fibrous tail connected to the head. It was found that there are cases where the main component is. Further, when various production conditions were examined, it was also found that a true spherical carbon precursor material without the tail portion was obtained depending on the production conditions.

The shaped carbon precursor having such a shape contributes to a high filling structure when the substantially spherical head is used as an electrode material or the like, as in the case of conventional mesophase carbon particles, and the fiber portion. Has been found to favor the formation of a contact between each particle.
The present invention has been made on the basis of this new finding, and includes the following configurations that provide carbon materials of various shapes including the substantially spherical lump portion.

Here, the manufacturing method of a molten carbon precursor is demonstrated. This is obtained by reacting an aromatic compound capable of electrophilic substitution with a cross-linking material.
The aromatic compound capable of electrophilic substitution is not particularly limited, but naphthalene, azulene, indacene, fluorene, phenanthrene, anthracene, triphenylene, pyrene, chrysene, naphthacene, picene, perylene, pentaphen, pentacene, etc. A condensed polycyclic hydrocarbon of 2 or more rings of the above: a heterocyclic group having 3 or more members such as indole, isoindole, quinoline, isoquinoline, quinoxane, phthalazine, carbazole, acridine, phenazine, phenanthridine and an aromatic hydrocarbon Condensed condensed heterocyclic compounds; aromatic oils such as anthracene oil, decrystallized anthracene oil, naphthalene oil, methylnaphthalene oil, tar, creosote oil, ethylene bottom oil, carbol oil, solvent naphtha; petroleum-based or coal-based Examples include pitch That. These aromatic components may have a substituent that does not adversely affect the crosslinking reaction, such as an alkyl group, a hydroxyl group, an alkoxy group, a carboxyl group, and the like. These aromatic compounds can be used singly or in combination of two or more. Furthermore, it can also be used in combination with a ring assembly compound such as biphenyl or binaphthalene.

  As the bifunctional crosslinking agent, various bifunctional compounds capable of crosslinking a plurality of components or a single component of the aromatic compound capable of the electrophilic substitution reaction can be used. Specifically, aromatic dimethylene halides such as xylene dichloride; aromatic dimethanols such as xylene glycol; aromatic dicarbonyls such as terephthalic acid chloride, isophthalic acid chloride, phthalic acid chloride, and 2,6-naphthalenedicarboxylic acid chloride Halide; aromatic aldehydes such as benzaldehyde, p-hydroxybenzaldehyde, p-methoxybenzaldehyde, 2,5-dihydroxybenzaldehyde, benzaldehyde dimethylacetanol, terephthalaldehyde, isophthalaldehyde, salicylaldehyde and the like are exemplified. These crosslinking agents can be used alone or in combination.

  The amount of the crosslinking agent used can be selected within a wide range depending on the characteristics of the aromatic compound capable of electrophilic substitution, and the amount of the crosslinking agent used per mole of the condensed polycyclic hydrocarbon and / or the condensed heterocyclic compound is It is about 0.1 to 5 mol, preferably about 0.5 to 3 mol. Moreover, about aromatic compound mixtures like pitches, it is 0.01-5 mol with respect to an average molecular weight, Preferably it is 0.05-3 mol.

The crosslinking reaction with the crosslinking agent is usually performed in the presence of an acid catalyst. As the acid catalyst, conventional acids such as Lewis acid and Bronsted acid can be used. Examples of Lewis acids include ZnCl ₂ , BF ₃ , AlCl ₃ , SnCl ₄ , and TiCl ₄ , and examples of Bronsted acids include organic acids such as p-toluenesulfonic acid, fluoromethanesulfonic acid, and xylenesulfonic acid. , Mineral acids such as hydrochloric acid, sulfuric acid, nitric acid. The acid catalyst is preferably a Bronsted acid.

  The amount of the acid catalyst used can be selected according to the reaction conditions and the reactivity of the aromatic compound capable of the electrophilic substitution reaction, for example, 0.01 to 10 molar equivalents, preferably 0, relative to the crosslinking agent. .5-3 molar equivalents.

  The crosslinking reaction can be performed using a solvent, but it is preferably performed in the absence of a solvent. The reaction is carried out, for example, at 80 to 400 ° C, preferably 100 to 350 ° C. The reaction can be performed in an inert gas atmosphere such as nitrogen, helium or argon, or in an oxidizing atmosphere such as air or oxygen. The obtained carbon precursor can be recovered as a solid resin when cooled to room temperature.

  Then, after carbonizing in a temperature range of 700 ° C. to 1500 ° C., graphitization can be performed in a temperature range of 2000 ° C. to 3100 degrees.

The molten carbon precursor is not limited to the above materials. When polymerization is not performed using a cross-linking material, coal tar pitch, petroleum pitch, coke, or the like can also be produced by firing in the above temperature range as a raw material.

  Pitch is a petroleum boiling residue, naphtha pyrolysis residue, petroleum bottom oil, coal liquefied oil, coal tar and other petroleum-based and coal-based heavy oils subjected to distillation operation to lower boiling point components below 200 ° C. The removed one and the one further subjected to heat treatment or hydrogenation treatment, specifically, mesophase pitch, hydrogenated mesophase pitch and the like can be mentioned as representatives.

〔Constitution〕
The characteristic configuration of the present invention is that a molten carbon precursor having a softening temperature of 250 to 350 ° C in a heated and flowing state is intermittently high-speed in a state in which the discharge amount is unevenly disturbed from a nozzle in a molten state of 300 to 500 ° C. a discharge step of discharging in a molten carbon precursor discharged intermittently, a cooling step of cooling vehicle formulated under a stream of air, and infusibilized heating the shaped carbon precursor through said cooling step, the carbonization step of carbonizing the infusibilized carbon precursor through said infusible step is executed in order, have a massive part of the general spherical, producing a carbon material in which the bulk portion in the fibrous carbon group is present dispersed There is in point to do.
The nozzle is preferably a spray nozzle. Specifically, the nozzle has a diameter of 0.1 to 2 mm, a nozzle hole number of 1 to 20, and molten carbon under discharge conditions of a back pressure of 1 to 10 atm. It is preferable that the precursor can be discharged.
It is preferable that the said discharge process is what discharges the molten carbon precursor whose softening temperature is 250-350 degreeC from the said nozzle in a 300-500 degreeC molten state.
Moreover, it is preferable that the said cooling process cools the molten carbon precursor discharged from the said nozzle under an air flow.
Moreover, it is preferable that the said infusibilization process heats a shaped carbon precursor to 270 degreeC-500 degreeC.
Furthermore, it is preferable that the said carbonization process heats an infusible carbon precursor to 700 to 1500 degreeC.

[Function and effect]
That is, according to the above-described new knowledge, the molten carbon precursor discharged from the nozzle in the discharge step has a shape having a substantially spherical lump portion.
If the cooling process which cools and solidifies this is performed, the said molten carbon precursor will become the shaped carbon precursor solidified by the various shape which has a substantially spherical lump part depending on conditions.

Specifically, the above-mentioned shaped carbon precursor usually has a tadpole-like configuration provided with a lump-shaped head and a string-like tail.
This is because the molten carbon precursor discharged from the nozzle is extruded and stretched in a linear shape, and the molten carbon precursor extruded in a linear shape is subjected to a force such as a string shape, a rod shape, or a linear shape. It is considered that this is derived from the fact that, while cutting, the force of gathering into a spherical shape by surface tension to balance and generating a lump portion is balanced and cooled and solidified into a special shape in which the lump lump portion and other portions are connected.

In other words, in the discharge step, if the force that is continuously discharged linearly with respect to the surface tension, it becomes a headed carbon-like carbon precursor material as a whole, and if the discharge conditions are such that the surface tension is superior, It is considered that a carbon precursor material in which the molten carbon precursors are aggregated so that almost the whole is a spherical lump is obtained.
And it is thought that the tadpole-like carbon precursor material was obtained by taking these intermediate conditions.

  If the molten carbon precursor discharged from the nozzle is cooled and solidified in a shape controlled by the discharge conditions, a carbon precursor material having a massive portion corresponding to the conditions can be obtained. This carbon precursor material can be used as a carbon material through an infusibilization step and a carbonization step.

  The cooling process may be any of air cooling, water cooling, and various other cooling methods. Moreover, those combinations may be sufficient.

  In addition, when the above-described method for producing a carbon material is performed, all aromatic components of the carbon precursor as a raw material are used for the production of the carbon material as compared with the case of obtaining mesophase microsphere carbon such as mesocarbon microbeads. (In other words, even a carbon component that does not easily become mesophase carbon can be used as a structure capable of forming a lump and graphitizing), so that a carbon material can be manufactured using an inexpensive raw material.

In addition, the discharged molten carbon precursor can be used almost as it is in the subsequent processing step, and a carbon material can be obtained with a high yield.
Therefore, according to the method for producing a carbon material, the production cost of the carbon material can be reduced, and the carbon material can be provided at a low cost.

  The shaped carbon precursor material obtained by the previous configuration has a low softening point and easily melts. Therefore, by making this infusible, it is possible to prevent inconveniences such as deformation of the massive portion and re-fusion of the carbon precursor materials.

[Function and effect]
If the nozzle is a spray nozzle, the carbon precursor material can be formed into a cotton shape when cooled and solidified while intermittently discharging the molten carbon precursor.
Specifically, it is preferable that the nozzle has a diameter of 0.1 to 2 mm and the number of nozzle holes of 1 to 20 because the cotton-like carbon precursor material is finely entangled. Moreover, if the discharge conditions are a back pressure of 1 to 10 atm, the discharged molten carbon precursor can be intermittently produced in a cotton-like shape, which is suitable for continuous production.

  Moreover, when a molten carbon precursor is discharged by such a nozzle, the discharged molten carbon precursor is cooled and solidified while being entangled while being generated in a large amount intermittently while generating a lump at the end. Therefore, the discharged molten carbon precursor has a lump-like portion at the end, and becomes a cotton shape in which the carbon precursor material solidified in a string shape is intertwined in a complicated manner. Therefore, it is suitable for processing the carbon precursor material as a nonwoven fabric.

In addition, the nonwoven fabric made of the carbon precursor material has uses as a heat insulating material and a buffer material, and since it is made of carbon, it is activated and used as a deodorant, an adsorbent, etc. by utilizing the properties as activated carbon. It can be used in various applications.
That is, a molten carbon precursor having a softening temperature of 250 ° C. to 350 ° C. can be easily melted, and can easily form a graphitized structure as a carbon precursor material to exhibit conductivity. It is empirically known to have a composition that can produce a material that can be manufactured, and in particular when forming a carbon precursor material as an electrode material or the like, a structure for exerting electrical conductivity is easily formed. It is preferable because it is possible. In addition, when extruding a molten carbon precursor from a nozzle, it is relatively easy to obtain a carbon precursor material having a desired shape by extruding at a temperature about 50 ° C. to 200 ° C. higher than the softening temperature of the molten carbon precursor. It is preferable because the discharge conditions can be controlled.

Furthermore, the molten carbon precursor discharged from such a nozzle can be configured to rapidly cool and solidify when it is atomized and exposed to an air flow after being discharged. The carbon precursor material can be produced, and the carbon precursor material can be produced intermittently and efficiently. Therefore, it has become possible to reduce the manufacturing cost and provide an inexpensive carbon precursor material.

Infusibilization of a carbon precursor material is usually performed by oxidizing the surface of the carbon precursor material. Such infusibilization is performed by heating in an air atmosphere containing an oxidizing gas such as NO ₂ , SO ₂ , and ozone. The temperature at this time is preferably 270 ° C to 500 ° C. This is because infusibilization is not rapidly performed at 270 ° C. or lower, and when the temperature rise rate is high at 500 ° C. or higher, the molten state is again melted.

In the carbonization step, the infusible carbon precursor is preferably heated to 700 ° C to 1500 ° C. If the temperature is lower than 700 ° C., sufficient carbonization cannot be expected, and if it is higher than 1500 ° C., it is uneconomical. More preferably, the carbonization step is performed at 800 ° C to 1200 ° C.

[Function and effect]
That is, when the molten carbon precursor in a heated fluid state is intermittently discharged from the nozzle at a high speed, a fibrous carbon group is obtained.
This fibrous carbon group is formed into a structure in which the molten carbon precursor is intermittently discharged at a high speed, the spherical portion and the fibrous portion are continuously connected, and is cut by applying stress, making it complicated It is thought that it was cooled and solidified in an intertwined state.

  When this carbon precursor material is observed in detail, the fibrous carbon has a structure having a head portion having a lump portion on one end side and a tail portion in which the fibrous carbon is connected in a string shape on the other end side. In some cases, the carbon precursor materials are gathered in a cotton form and have a structure in which massive portions are dispersedly arranged in cotton mainly composed of fibrous carbon. The balance between the size of the lump and the length of the fibrous carbon depends on conditions such as the shape and size of the nozzle, the discharge pressure of the molten carbon precursor, and the speed, but the molten carbon precursor is intermittently removed from the nozzle. By making it discharge, the lump part dispersion | distribution carbon material in which the said lump part disperse | distributes and exists in a cotton-like fibrous carbon group can be manufactured.

  The carbon precursor material thus obtained can be easily molded into a non-woven fabric, and the molded carbon precursor material can have a high filling structure, and the tail portion is adjacent to another carbon. Since the structure in contact with the precursor material is easily realized, a contact point can be formed between the bulk parts, leading to improvement in physical properties of the carbon material as a whole, and the carbon material is graphitized to form an electrode This contributes to increasing the conductivity when the film is formed.

〔Constitution〕
Moreover, the manufacturing method of the lump part dispersion | distribution graphite material of this invention performs the graphitization process which graphitizes the carbon material obtained by the manufacturing method of the said carbon material. Moreover, it is preferable that the said graphitization process is heated at 2000 to 3100 degreeC.

[Function and effect]
That is, since the carbon material is oxidized in its surface and maintains a predetermined shape, the carbon material can be made into a graphite material in a state where the shape is maintained by graphitization.
At this time, a discharge capacity sufficient as a battery negative electrode material cannot be obtained at a low temperature of 2000 ° C. or lower, and sublimation occurs at a high temperature of 3100 ° C. or higher, resulting in a decrease in yield. More preferably, the graphitization step is performed at 2000 ° C to 3000 ° C.

[Function and effect]
That is, according to the manufacturing method described above, the molten carbon precursor does not become a perfect spherical shape depending on conditions, but becomes a shaped carbon precursor of various shapes, but has a shape having a substantially spherical lump portion. A shaped carbon precursor formed by solidification is produced. The shaped carbon precursor can form a high filling structure due to the lump.

  As far as the electrode material is concerned, when the bulk portion is filled with high filling efficiency, the volume energy density is improved, and the contact points between the particles are increased due to the entanglement of the fiber portion, resulting in high conductivity. Secured, and improved cycle characteristics can be expected.

  Furthermore, when the carbon precursor material is a carbon precursor material having a spherical head and a string-like tail, and the spherical head has a spherical shape with a diameter of 0.001 to 2 mm, these are: As a whole, it is cotton-like, and the shape with a lump at the end of the fibrous carbon is intricately intertwined. It is difficult to fray, can be easily processed into a non-woven fabric, and can realize a structure in which the massive portions are connected to each other via the fibrous carbon in a state of being consolidated into a non-woven fabric. In addition, when the carbon material processed into the cotton-like or non-woven fabric is compared with the carbon material using the conventional carbon fiber, the carbon material has a pointed portion at the end of the fiber covered with the lump portion. , Feel good when touched by people.

  In addition, as a dimension of a carbon material preferable as an electrode material, the diameter of the head is about 5 μm to 40 μm. By adopting such a configuration, the obtained carbon material is sufficiently dispersed, and can be used as an electrode material by being infusibilized, carbonized, graphitized as it is without passing through crushing and the like, and High degree of filling and conductivity can be expected. In addition, compared with conventional electrode materials using carbon fibers, there was a problem that in the conventional case, the sharp portion of the end of the carbon fibers may flutter and damage or break through a thin film such as a separator. On the other hand, in the thing of this invention, since a lump part is spherical, there exists an advantage that it is hard to produce such a problem.

  Therefore, carbon materials that can be used in various applications and can exhibit various preferable physical properties can be easily and inexpensively manufactured, and can be used for the spread of carbon materials in various fields. In particular, application as an electrode material for fuel cells is expected.

It is a flowchart which shows the manufacturing method of the carbon precursor material of this invention. It is a figure which shows a melting pitch supply apparatus. It is a microscope picture (x43) of the shaped carbon precursor A. It is a microscope picture (x500) of the shaped carbon precursor A. It is a microscope picture (x1000) of the shaped carbon precursor A. It is a fragmentary sectional view of a battery electrode. It is a microscope picture (x2000) of the shaped carbon precursor B.

  Below, the manufacturing method and carbon material of the carbon material of this invention are demonstrated. Preferred examples are described below, but these examples are described in order to more specifically illustrate the present invention, and various modifications can be made without departing from the spirit of the present invention. The present invention is not limited to the following description.

[Method for producing carbon material]
An example of producing a graphitized carbon material (graphite material) as an electrode material by the carbon material production method of the present invention is shown in FIG.

<1>
First, a discharge process is performed using the melt pitch supply apparatus 1 (refer FIG. 2) which discharges from a nozzle, hold | maintaining the melt pitch as a molten carbon precursor in a heat-melting state. The discharged molten pitch is solidified while being air-cooled, and becomes a shaped pitch as a flocculent shaped carbon precursor (cooling step). The shaped pitch is further water cooled by a cold water bath (cooling step).

<2>
The obtained shaped pitch is infusibilized by the infusibilization step and becomes an infusibilized pitch as a carbon precursor material. The infusibilization step may be performed by various known methods, and can be realized, for example, by heating in air at 300 ° C. for 60 minutes.

<3>
Next, the infusibilized pitch that has undergone the infusibilization step is further subjected to a carbonization step.
The carbonization step may be performed by various known methods, for example, by heating in an inert atmosphere at 1000 ° C. for 60 minutes. Thereby, the infusible pitch is carbonized and becomes a carbon material.

<4>
The carbon material that has undergone the carbonization step is further subjected to a graphitization step. The graphitization step may be performed by various known methods, and can be realized, for example, by heating at 2800 ° C. for 60 minutes in an inert atmosphere.

  The graphitized graphite material (graphitized carbon material) thus obtained is used as an electrode material that can be coated and fired on a substrate after being mixed with a binder in a paste after being mixed with a binder.

  Hereinafter, more specific examples will be described.

<Carbon material A>
[Melting pitch feeder]
As shown in FIG. 2, the melt pitch supply device 1 is provided with a tank 2 capable of holding the raw material pitch as a melt flow state melt pitch, and the raw material pitch previously supplied into the tank 2 is heated and melted to melt the melt pitch. As a heating device 3.

  A nozzle 4 for discharging a melt pitch is provided at the lower end of the tank 2, and a valve for supplying gas into the tank 2 and a valve for discharging gas are provided at the upper end of the tank 2. By alternately operating the two, a back pressure is intermittently applied to the molten carbon precursor in the hopper so that the molten pitch can be discharged from the nozzle 4. A cooling device 6 is provided below the tank 2 to receive a drop supply of the molten pitch discharged from the nozzle 4 and to cool the molten pitch with water.

[Heating device and melt pitch]
As the raw material pitch, a pitch (product type AR24Z, softening point 293.9 ° C.) manufactured by Mitsubishi Gas Chemical Co., Ltd. is used, and the heating device 3 is heated and controlled so as to maintain the raw material pitch in a molten state of 400 ° C. .

〔nozzle〕
As the nozzle 4, for example, a nozzle manufactured by Ikeuchi Co., Ltd. (model number KB series) is used. The nozzle 4 is a so-called spray nozzle having one nozzle port having a diameter of about 0.1.

[Supply valve]
The gas supply valve and the gas discharge valve have a structure in which the back pressure is adjusted by manually switching the supply valve and the gas discharge valve so that supply control is possible so that a pressure of 1 to 10 atm is loaded in the tank 2. .

[Melting pitch discharge operation]
With the above-described configuration, the raw material pitch supplied to the melt pitch supply device 1 is melted at 400 ° C. by the heating device 3 in the tank 2 and discharged from the nozzle 4 at a back pressure of 4 atm. And it receives air cooling in the nozzle opening vicinity of the said nozzle, and becomes a shaping pitch. When a predetermined amount of this shaping pitch is generated, the discharge valve is opened to lower the back pressure, and the discharge of the molten pitch from the nozzle port is once interrupted to drop the shaping pitch downward. Further, when the shaping pitch is dropped downward, the nozzle opening of the nozzle 4 is opened again, and intermittent discharge control is performed so that the molten pitch can be discharged. Specifically, one discharge time is about 0.5 seconds, and discharge is performed at intervals of about 1 second.

[Shaping pitch]
The obtained shaped carbon precursor falls linearly when the back pressure is low, but as the back pressure rises, the fibrous carbon spreads in the form of cotton and is cooled and solidified in a complex entangled state. Is done.

(Production conditions 1)
Raw material pitch: Pitch made by Mitsubishi Gas Chemical Company (variety AR24Z, softening point 293.9 ° C)
Nozzle: Ikeuchi Co., Ltd. nozzle (model number KB series)
Heating temperature: Temperature: 400 ° C
Back pressure: Pressure: 4 atmospheres: Load interval: 0.5 seconds every 1 second

[Infusibilization process]
When the shaped pitch A was infusibilized under the infusibilization condition 1, an infusible pitch A (see FIG. 3) was obtained.

(Infusibilization condition 1)
Atmosphere: Environmental gas: Air temperature: 300 ° C
Time: 1 hour

[Carbonization process]
When the infusibilized pitch A was carbonized under carbonization condition 1, carbon material A (see FIGS. 4 and 5) was obtained.

(Carbonization condition 1)
Environmental gas: Argon temperature: 1000 ° C
Time: 1 hour [structure of carbon material]
As shown below, when the carbon material A obtained under the following production condition 1 is observed in detail, as shown in FIGS. 3 to 5, the fibrous carbon has a lump on one end side. A carbon precursor material having a structure having a head portion and a tail portion in which fibrous carbon is connected in a string shape on the other end side is a carbon precursor material gathered in a cotton shape, It was found that the structure was such that lump portions were dispersedly arranged in the main cotton-like fibrous carbon group.

[Graphitization process]
When the infusibilized pitch A was graphitized under graphitization condition 1, a graphite material was obtained.

(Graphitization condition 1)
Environmental gas: Argon temperature: 2800 ° C
Time: 1 hour

[Creation of negative electrode body]
6 wt% polyvinylidene fluoride was added to the graphite material, and N, N-dimethylformamide was mixed as a solvent to form a slurry. Then, the slurry was apply | coated on the copper foil roll at a fixed speed | rate using the negative electrode molding machine, and the electrode of thickness 100-140 micrometers was produced. The electrode thus obtained was vacuum-dried at 200 ° C. for 6 hours.

[Battery creation]
(Example 1)
In addition to the above-obtained negative electrode body, LiCoO2 was used as the positive electrode body, and the electrolyte was a solution of LiPF6 dissolved in a mixed solvent of ethylene carbonate and diethyl carbonate at a ratio of 1 mol / l, and polypropylene as the separator. A lithium secondary battery was prepared using a nonwoven fabric. A cross-sectional view thereof is shown in FIG . The lithium secondary battery includes a positive electrode 11 made of a positive electrode active material, a negative electrode 13 including the negative electrode body, and a separator 12 interposed between the positive electrode 11 and the negative electrode 13. The separator 12 is impregnated with an electrolytic solution. The positive electrode 11, the separator 12, and the negative electrode 13 are accommodated in a case 14, and the opening of the case 14 is sealed with a sealing plate 15. A current collector 16 made of nickel mesh, metal wire mesh, or the like is disposed between the case 14 and the negative electrode 11. Reference numeral 17 denotes an insulating packing.

(Comparative Example 1)
Evaluation was performed in the same manner as in Example 1 except that mesocarbon microbeads (average particle size 25 microns, fired at 2800 ° C.) manufactured by Osaka Gas Chemical Co., Ltd. were used as the negative electrode material.

(Measurement of battery characteristics)
The discharge characteristics of the lithium secondary battery obtained in this experiment were measured.
The charging and discharging of the batteries of Example 1 and Comparative Example 1 were repeated 100 cycles under the conditions of a constant current of 400 mA, a charging upper limit voltage of 4.2 V, and a discharging lower limit voltage of 2.5 V at an environmental temperature of 25 ° C. The initial capacity of each battery was 2.0 Ah.
In the battery of Example 1, the capacity deterioration rate was as small as 3% even after 100 cycles, and the capacity was almost maintained. On the other hand, in the battery of Comparative Example 1, the capacity deterioration rate associated with the cycle was remarkable at 7%, and the output reduction was remarkable. Both were spherical carbons, but it was demonstrated that the cycle characteristics differed depending on the number of contact points depending on the presence or absence of the fiber part.

<Carbon material B>
As the raw material carbon precursor, isotropic pitch (1% quinoline insoluble content, softening point 287.2 ° C) manufactured by Osaka Gas Chemical Co., Ltd. is used, and the raw material pitch is controlled by heating so as to maintain the molten state at 420 ° C. A carbon material B was produced in the same manner as the carbon material A, except that the back pressure was 5 atm. In the molten state of the molten carbon precursor, the viscosity is controlled to 10 poise or less. As a result, it was confirmed that true spherical carbon particles were generated as a shaped carbon precursor (see FIG. 7 ).
The obtained shaped carbon precursor was infusibilized in the same manner as in Example 1, and then carbonized at 1100 ° C. (in this case, no graphitization treatment), and in the same manner as in Example 1. Electrode evaluation was performed.

(Measurement of battery characteristics)
As a result, 100 cycles were repeated under the conditions of a constant current of 400 mA, a charge upper limit voltage of 4.1 V, and a discharge lower limit voltage of 2.5 V under an environmental temperature of 25 ° C. The initial capacity was 2.0 Ah.
Even after 100 cycles, the capacity deterioration rate was as low as 4%, and the capacity was almost maintained, indicating improved performance over the comparative example.

Claims (7)

A discharge step of discharging a molten carbon precursor having a softening temperature of 250 to 350 ° C. in a heated and flowing state intermittently at a high speed in a molten state of 300 to 500 ° C. in a state in which the discharge amount is unevenly disturbed from the nozzle; A cooling process for cooling and shaping the molten carbon precursor discharged intermittently under an air flow, an infusibilization process for heating the shaped carbon precursor that has undergone the cooling process, and an infusible process that has undergone the infusibilization process. the carbonization step of carbonizing the infusibilized carbon precursor was performed in sequence, the general spherical massive portions have a, massive portion dispersed carbon material the massive portion in the fibrous carbon group to produce a carbon material present in dispersed Production method. The method for producing a mass-dispersed carbon material according to claim 1, wherein the nozzle is a spray nozzle. The lump part dispersion according to claim 1 or 2, wherein the nozzle has a diameter of 0.1 to 10 mm, a nozzle hole number of 1 to 20, and can discharge the molten carbon precursor under discharge conditions of a back pressure of 1 to 10 atm. A method for producing a carbon material. The method for producing a massive part-dispersed carbon material according to any one of claims 1 to 3 , wherein the infusibilization step heats the shaped carbon precursor to 270C to 500C. The method for producing a mass-dispersed carbon material according to any one of claims 1 to 4 , wherein the carbonization step heats the infusible carbon precursor to 700 ° C to 1500 ° C. The manufacturing method of the lump part dispersion | distribution graphite material which performs the graphitization process of graphitizing the carbon material obtained by the manufacturing method of the carbon material of any one of Claims 1-5 which passed the said carbonization process. The method for producing a massive part-dispersed graphite material according to claim 6 , wherein the graphitizing step heats the carbon material to 2000 ° C to 3100 ° C.