JP3534391B2 - Carbon material for electrode and non-aqueous secondary battery using the same - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a carbon material for electrodes and a non-aqueous secondary battery using the same. For more details,
The present invention relates to a carbon material for an electrode, preferably a carbon material for a negative electrode, which can form a non-aqueous secondary battery having a high capacity and a favorable rapid charge / discharge property.

[0002]

2. Description of the Related Art In recent years, with the miniaturization of electronic devices, a high capacity secondary battery has been required. In particular, lithium secondary batteries, which have higher energy density than nickel-cadmium batteries and nickel-hydrogen batteries, have been receiving attention. Attempts were initially made to use lithium metal as the negative electrode material, but during repeated charging and discharging, lithium was deposited in a resin (dendritic) form, penetrated the separator, and reached the positive electrode, short-circuiting both electrodes. It turned out to be dangerous. Therefore, carbon-based materials that can prevent the generation of dendrites have been attracting attention instead of metal electrodes.

As a non-aqueous electrolyte secondary battery using a carbon-based material, a battery using a non-graphitizable carbon material having a low crystallinity as a negative electrode material was first put on the market. Subsequently, batteries using graphites with high crystallinity were put on the market and have reached the present. The electric capacity of graphite is theoretically maximum at 372 mAh / g, and a battery having a high charge / discharge capacity can be obtained by appropriately selecting an electrolytic solution. Further, JP-A-4-1716
The use of a carbonaceous material having a multi-layer structure, as shown in Japanese Patent Publication No. 77, has also been studied. This is the advantage of graphite with high crystallinity (high capacity and small irreversible capacity) and disadvantage (decomposes propylene carbonate-based electrolyte) and the advantage of carbonaceous material with low crystallinity (excellent stability with electrolyte). ) And disadvantages (large irreversible capacity) are combined to make use of each other's advantages while compensating for the disadvantages.

Graphites (graphite and multi-layer carbonaceous materials containing graphite) have higher crystallinity and higher true density than non-graphitizable carbon materials. Therefore, if the negative electrode is formed by using these carbon materials such as graphite, a high electrode filling property can be obtained and the volume energy density of the battery can be increased. When the negative electrode is composed of graphite-based powder, a method is generally used in which powder and a binder are mixed, a dispersion medium is added to form a slurry, which is applied to a metal foil as a current collector, and then the dispersion medium is dried. It is used for. At this time, it is general to provide a step of further compression molding for the purpose of pressure-bonding the powder to the current collector, making the electrode plate thickness of the electrode uniform, and improving the electrode plate capacity. By this compression step, the electrode plate density of the negative electrode is improved, and the energy density per volume of the battery is further improved.

However, a general graphite material having high crystallinity and industrially available has a particle shape of scale, scale, or plate. The particle shape is scale-like, scale-like,
It is considered that the plate-like shape is derived from the fact that the carbon crystal network planes become graphite crystalline graphite by stacking growth in one direction. When these graphite materials are used for the negative electrode of a non-aqueous electrolyte secondary battery, they show a large discharge capacity with little irreversible capacity due to their high crystallinity, but the particle shape is scaly, scaly,
The plate-like shape has a small amount of crystal edge surfaces that allow lithium ions to enter and exit, and a large amount of basal surfaces that do not participate in the entry and exit of lithium ions, resulting in a decrease in capacity during rapid charge and discharge at high current density. Can be seen. Also,
When the graphite particles are processed into the electrode plate through the electrode plate manufacturing process,
The electrode plate density increases according to the degree of compression, but on the other hand, there is a problem in that the movement of lithium ions is hindered because the particle gaps are not sufficiently secured, and the rapid charge / discharge characteristics of the battery deteriorate.

Furthermore, when plate-like graphite particles are formed as an electrode, the plate surface of the powder is highly likely to be parallel to the electrode plate surface due to the influence of the slurry coating process and the electrode plate compression process. Arranged. Therefore, the edge faces of the graphite crystallites forming the individual powder particles are formed in a positional relationship perpendicular to the electrode faces with a relatively high probability. When charging / discharging in such an electrode plate state, the lithium ions that move between the positive and negative electrodes and are inserted into and desorbed from the graphite must once go around the powder surface, and the movement efficiency of the ions in the electrolyte solution is high. There was also a problem in that it was extremely disadvantageous. Further, the voids left in the electrode after molding have a problem that they are closed to the outside of the electrode because the particles have a plate-like shape. That is, there is a problem that the free circulation of the electrolytic solution with the outside of the electrode is hindered, and the movement of lithium ions is hindered.

[0007] On the other hand, graphite of mesocarbon microbeads is used as a negative electrode material having a high ratio of crystal edge faces into and out of which lithium ions enter, and a spherical shape capable of ensuring voids necessary for the movement of lithium ions in the electrode plate. Compounds have been proposed and already commercialized. If the ratio of the edge surface is high, the area where lithium ions can move in and out of particles increases,
Also, if the morphology is spherical, even after the above-mentioned electrode plate compression step, the individual powder particles do not have a selective arrangement, the isotropic property of the edge surface is maintained, and the ion in the electrode plate is maintained. The moving speed of is maintained well. Furthermore, the voids remaining inside the electrode are connected to the outside of the electrode due to the particle shape, so lithium ions are relatively free to move, and the electrode structure is compatible with rapid charging and discharging. . However, since the mesocarbon microbeads have a low crystal structure level as graphite, they have an electric capacity limit of 300.
It is already widely known that it is as low as mAh / g and is inferior to scaly, scaly, and plate-like graphite.

Focusing on these problems, an invention has been made in which the shape of graphite used in a non-aqueous electrolyte secondary battery is specified. For example, Japanese Unexamined Patent Publication No. 8-180873 discloses an invention in which the ratio of scale-like particles to particles not relatively scale-like is specified. On the other hand, JP-A-8-836
On the contrary, Japanese Patent No. 10 describes that scale-like particles are preferable.

[0009]

SUMMARY OF THE INVENTION Practical batteries are required to have electrodes having both high electric capacity and excellent rapid charge / discharge characteristics. However, an electrode sufficiently satisfying such requirements has not yet been provided. For this reason,
In particular, it has been strongly desired to improve the rapid charge / discharge property of the flaky, scaly, and plate-like graphite materials. Therefore, the present invention has made it an object to meet such a conventional demand and solve the problems of the conventional technology. That is, it was an issue to be solved to provide a carbon material for an electrode, which has a high electrode filling property of the material, a high energy density, and an excellent rapid charge / discharge property.

[0010]

In order to solve the above-mentioned problems, the inventors of the present invention have conducted extensive studies, and as a result, in order to improve the performance of the electrode, the inside of the graphite particles is highly crystalline. The high discharge capacity is maintained, and the plate-like graphite particles are relatively thick in the thickness direction, and the part near the particle surface, especially the basal surface, is rough (the basal surface has cracks or bends, and By using graphite particles with a high abundance ratio of the edge part due to the exposed edge part), the amount of the part where lithium ions can go in and out is increased, and the shape of the graphite particle is closer to a spherical shape It was found that an electrode with high capacity rapid charge / discharge characteristics and excellent cycle characteristics can be obtained by increasing the isotropic arrangement of particles, that is, the isotropic arrangement of edges by using a carbon material with high To get Was Tsu.

The carbon material for electrodes of the present invention has been completed on the basis of such findings. First, the interplanar spacing (d002) of the (002) plane by the wide-angle X-ray diffraction method is 0.
Less than 337 nm, the crystallite size (Lc) is more than 90 nm, R value is the peak intensity ratio of 1360 cm ^-1 to the peak intensity of 1580 cm ^-1 in the argon ion laser Raman spectrum is 0.20 or more and a tap density of 0.75g / Cm ³ or more, and secondly, in the present invention, as a carbon material for electrodes, a carbon material having the above characteristics is mixed with an organic compound, and then the organic compound is carbonized. Which is characterized by using a multi-layered carbon material, and thirdly, a negative electrode containing a carbonaceous material capable of inserting and extracting lithium, a positive electrode, and a solute and an organic solvent. In a non-aqueous electrolyte secondary battery having the following non-aqueous electrolyte solution, a carbonaceous material or a multilayer structure in which at least a part of the carbonaceous material has the above characteristics A nonaqueous secondary battery, which is a quality material. Further, the present invention is an average before and after treatment.
Reduce the particle size so that the particle size ratio is 1 or less and
Higher tap density and argon ion laser
Peak intensity at 1580 cm ^-1 in Man spectrum
R value, which is the peak intensity ratio of 1360 cm ⁻¹ to
By theory, the mechanical energy treatment is 1.5 times or more.
A method for producing the carbon material for an electrode, characterized in that
It also provides the law.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The carbon material for electrodes, the multi-layered carbon material for electrodes and the secondary battery of the present invention will be described in detail below.

Carbon Material for Electrodes The carbon material for electrodes of the present invention is (0
02) plane spacing (d002) and crystallite size (L
c), and 1360c for the peak intensity at 1580 cm ^-1 in the argon ion laser Raman spectrum.
It is characterized in that the R value, which is the peak intensity ratio of m ⁻¹ , and the tap density are within a predetermined range. That is, in the carbon material for electrodes of the present invention, the interplanar spacing (d002) of the (002) plane by the wide-angle X-ray diffraction method is less than 0.337 nm, and the crystallite size (Lc) is 90 nm or more. The electrode carbon material for the invention, R value is the peak intensity ratio of 1360 cm ^-1 to the peak intensity of 1580 cm ^-1 in the argon ion laser Raman spectrum is 0.20
Or more, preferably 0.23 or more, particularly preferably 0.2
Especially, 5 or more can be selected and used. The upper limit of the R value may be 0.9 or less, preferably 0.7 or less, and particularly preferably 0.5 or less. Furthermore, the carbon material for electrodes of the present invention is characterized by having a tap density of 0.75 g / cm ³ or more, preferably 0.80 g / cm ³ or more, and the upper limit is preferably 1.40 g / cm ^{3. It is 3} or less, more preferably 1.20 g / cm ³ .

The interplanar spacing (d002) and crystallite size (Lc) of the (002) plane by the wide-angle X-ray diffraction method are values representing the crystallinity of the carbon material bulk, and the interplanar spacing (d002) of the (002) plane. The smaller the value is, and the larger is the crystallite size (Lc), the higher is the crystallinity of the carbon material. Further, the index in the present invention, R value is the peak intensity ratio of 1360 cm ^-1 to the peak intensity of 1580 cm ^-1 in the argon ion laser Raman spectrum representing the crystallinity in the vicinity of the surface of the carbon particles (from the particle surface to 100Å position) The larger the R value, the lower the crystallinity or the more disordered the crystal state.

That is, in the present invention, the interplanar spacing (d002) of the (002) plane by the wide-angle X-ray diffraction method is 0.337.
nm, a crystallite size (Lc) of 90 nm or more, and a peak intensity of 1580 cm ^-1 in an argon ion laser Raman spectrum at 1360 cm.
^A carbon material for an electrode having an R value of 0.20 or more, which is a peak intensity ratio of ^-1 , has a high crystallinity of carbon particles, but the surface vicinity of the particles is rough and highly distorted, that is, the abundance of edge portions. Indicates that is higher. Furthermore, a carbon material for electrodes having a tap density of 0.75 g / cm ³ or more means that the filling rate of the electrodes is high and the particle shape is round.

In the present specification, "tap density" means 1
It means the bulk density after 000 taps, and is represented by the following formula.

[Equation 1] Tap density = filled powder mass / powder filled volume

The packing structure of powder particles depends on the size and shape of particles, the degree of interaction force between particles, and the like.
In this specification, the tap density is used as an index for quantitatively discussing the filling structure. Various formulas have been proposed as formulas that represent tap filling behavior. As an example, the following formula:

## EQU00002 ## .rho .-. _Rho.n = A.exp (-k.n) can be mentioned. Here, ρ is the bulk density at the end of filling, ρ _n is the bulk density at the time of filling n times, and k and A are constants. The "tap density" referred to in this specification is 20c.
Bulk density (ρ when 1000 taps are filled into an m ³ cell)
₁₀₀₀ ) is regarded as the ultimate bulk density ρ.

The physical properties of the carbon material for electrodes of the present invention are not particularly limited as long as they satisfy these conditions. However, the preferred ranges of other physical properties are as follows. The carbon material for electrodes of the present invention has an average particle size of 2 to
The range of 50 μm is preferable, the range of 4 to 35 μm is preferable, the range of 5 to 27 μm is more preferable, and the range of 7 to 19 μm is further preferable. In addition, the range described by "-" in this specification shows the range containing the numerical value described before and behind "-".

The electrode carbon material of the present invention, the BET specific surface area is less than 18m ² / g, still more 15 m ² / g or less, and particularly preferably not more than 13m ² / g. In addition, 1580c in Argon ion laser Raman spectrum
The half-value width of the m- ¹ peak is preferably 20 cm- ¹ or more, and the upper limit is preferably 27 cm- ¹ or less,
21 to 26 cm ⁻¹ can be selected and used.
Further, the carbon material for electrodes of the present invention has a true density of 2.21 g.
/ Cm ³ or more, preferably 2.22 g / cm ³
It is more preferable that it is not less than 2.24 g / cm 3.
It is preferably ³ or more.

The carbon material for an electrode of the present invention is a flow formula capable of calculating an average shape parameter by taking an image of thousands of particles dispersed in a liquid one by one using a CCD camera. In a particle image analyzer, the average circularity for all particles (the ratio of the perimeter of a circle equivalent to the particle area as the numerator and the perimeter of the projected image of the particle as the denominator, the particle image is close to a perfect circle) It is preferably about 1, and the smaller the particle image becomes, the smaller the particle image becomes. In addition, the carbon material for electrodes of the present invention has a 136
Peak area near 0 cm ^-1 (1260-1460 cm
G value is the area ratio of the peak area in the vicinity of 1580 cm ^-1 (integrated value of 1480～1680Cm ^-1) to the integral value) of ^-1, preferably less than 3.0, more preferably 2.
It is less than 5, and the lower limit is not particularly limited, but is preferably 1.0 or more.

As the carbon material for electrodes of the present invention, a carbon material produced naturally or an artificially produced carbon material may be used. Further, the method for producing the carbon material for electrodes of the present invention is not particularly limited. Therefore, it is possible to select and obtain the carbonaceous material for electrodes having the above-mentioned characteristics by using a classification means such as sieving or air classification. The most preferable production method is a method of producing a carbon material for an electrode by subjecting a naturally occurring carbon material or an artificially produced carbon material to mechanical energy treatment for modification. Therefore, the mechanical energy processing will be described below.

The raw material carbon material to which the mechanical energy treatment is applied is a natural or artificial graphite powder or a carbon powder which is a graphite precursor. These graphite powders and carbonaceous powders have a surface spacing (d002) of 0.340 nm.
Less, the crystallite size (Lc) is 30 nm or more, and the true density is 2.25 g / cm ³ or more. Among them, those having a surface spacing (d002) of less than 0.338 nm are more preferable, and those having a surface spacing (d002) of less than 0.337 nm are more preferable. Further, the crystallite size (Lc) is more preferably 90 nm or more, further preferably 100 nm or more. The average particle size is preferably 10 μm or more, more preferably 15 μm or more,
Those having a thickness of 20 μm or more are more preferable, and those having a thickness of 25 μm or more are even more preferable. The upper limit of the average particle size is preferably 1 mm or less, 500 μ
It is more preferably m or less, still more preferably 250 μm or less, still more preferably 200 μm or less.

The graphite powder and the carbonaceous powder can be used as raw materials regardless of whether they have high crystallinity or low crystallinity. Since a raw material having low crystallinity has a relatively low plane orientation and a disordered structure, a pulverized surface having a relatively isotropic pulverized surface can be easily obtained by mechanical energy treatment. Further, the crystallinity can be enhanced by further performing heat treatment after the mechanical energy treatment.

Among the carbon materials to be subjected to the mechanical energy treatment, as highly crystalline carbon material having a developed hexagonal mesh plane structure of carbon, highly oriented graphite in which the hexagon mesh plane is largely grown in a plane orientation, An isotropic high-density graphite in which highly oriented graphite particles are aggregated in the same direction can be mentioned. As highly oriented graphite, natural graphite from Sri Lanka or Madakaskar, so-called quiche graphite precipitated from molten iron as supersaturated carbon, and artificial graphite having a high degree of graphitization can be exemplified as preferable ones. .

Natural graphite may be scaly graphite (Flake Graphite ) or scaly graphite (Crystalline (Vein) G , depending on its properties.
raphite ), soil graphite (Amorphousu Graphite ) (" Granular and granular process technology collection" (Industrial Technology Center Co., Ltd., published in 1974 ), graphite section, and "HANDBOOK
OF CARBON, GRAPHITE, DIAMOND AND FULLERENES "(Noyes
Publications) reference)). The degree of graphitization was highest for scaly graphite at 100%, followed by scaly graphite at 99.
It is high at 9%, but soil graphite is low at 28%. Flake graphite, which is natural graphite, is produced in Madagascar, China, Brazil, Ukraine, Canada, etc., and scaly graphite is mainly produced in Sri Lanka. Soil graphite is mainly produced in the Korean Peninsula, China and Mexico. Among these natural graphites, soil graphite generally has a small particle size and low purity. On the other hand, scaly graphite and scaly graphite have advantages such as low degree of graphitization and low amount of impurities, and thus can be preferably used in the present invention.

The artificial graphite is petroleum coke or coal pitch coke 1500 to 30 in a non-oxidizing atmosphere.
It can be produced by heating at a temperature of 00 ° C. or higher. In the present invention, any artificial graphite can be used as a raw material as long as it exhibits high orientation and high electrochemical capacity after mechanical energy treatment and heat treatment.

The mechanical energy treatment for these carbon materials is performed so that the average particle size ratio before and after the treatment is 1 or less. The “average particle size ratio before and after treatment” is a value obtained by dividing the average particle size after treatment by the average particle size before treatment. The average particle size referred to here is a volume-based particle size distribution measured by a laser type particle size distribution measuring device. When measured with a laser type particle size distribution measuring device, even particles having anisotropy in shape are isotropically averaged to obtain a particle size distribution substantially converted into a sphere.

In the mechanical energy treatment performed for producing the carbon material for electrodes of the present invention, the average particle size ratio before and after the treatment is set to 1 or less. On the other hand, when granulated, the average particle size ratio becomes 1 or more and the tap density also increases. The granulated powder and granules are not preferable because they are fully expected to return to the state before treatment in the final molding process.

The mechanical energy treatment is to control the particle shape while reducing the particle size so that the average particle diameter ratio before and after the treatment of the powder particles becomes 1 or less. Crush,
Among the engineering unit operations that can be used for particle design such as classification, mixing, granulation, surface modification, and reaction, mechanical energy processing belongs to grinding processing.

Grinding means applying a force to a substance to reduce its size and to control the particle size, particle size distribution and packing property of the substance. The crushing treatment is classified according to the type of force applied to the substance and the treatment form. The force applied to a substance is roughly divided into four: a force for breaking (impact force), a force for crushing (compressing force), a force for crushing (grinding force), and a force for shaving (shearing force). On the other hand, the treatment forms are roughly classified into volume pulverization in which cracks are generated inside the particles and propagated, and surface pulverization in which particle surfaces are scraped off. Volume pulverization proceeds by impact force, compression force, and shearing force, and surface pulverization proceeds by grinding force and shearing force. Grinding is a process that combines various types of force applied to these substances and processing forms. The combination can be appropriately determined according to the processing purpose.

The crushing may be carried out by chemical reaction such as blast or volume expansion, but it is generally carried out by using a mechanical device such as a crusher. It is preferable that the pulverization treatment used for producing the carbon material for an electrode of the present invention is such that the ratio of the surface treatment finally becomes high regardless of the presence or absence of volume pulverization. This is because the surface grinding of the particles is important for removing the corners of the graphitic or carbonaceous particles and introducing roundness into the particle shape. Specifically, the surface treatment may be performed after the volume pulverization has progressed to some extent,
Only the surface treatment may be performed without proceeding the volume pulverization, or the volume pulverization and the surface treatment may be simultaneously performed. Finally, it is preferable to carry out a pulverization treatment so that the surface pulverization proceeds and the corners are removed from the surface of the particles.

The device for performing the mechanical energy treatment is selected from those capable of performing the above-mentioned preferable treatment. As a result of examination by the present inventors, it has been clarified that a device which repeatedly applies mechanical actions such as compression, friction, shearing force, etc., mainly including impact force, including particle interaction, to the particles is effective. Specifically, it has a rotor with a large number of blades installed inside the casing, and the high-speed rotation of the rotor causes a machine such as impact compression, friction, and shearing force to the carbon material introduced inside. It is preferable to use an apparatus that performs a surface treatment while exerting a mechanical action and progressing volume pulverization. Further, it is more preferable that the carbon material has a mechanism for repeatedly giving a mechanical action by circulating or convection the carbon material.

As an example of such a preferred device,
A hybridization system manufactured by Nara Machinery Co., Ltd. can be mentioned. When processing using this device, the peripheral speed of the rotating rotor is 30-100 m /
Seconds are preferred, 40-100 m / s are more preferred, and 50-100 m / s are even more preferred. Further, the treatment can be performed by simply passing the carbon material, but it is preferable to circulate or stay in the device for 30 seconds or more, and it is preferable to circulate or stay in the device for 1 minute or more. More preferable.

The true density of the carbonaceous powder used as the raw material is 2.25.
If it is less than g / cm ³ and the crystallinity is not so high,
After the mechanical energy treatment, it is preferable to further perform a heat treatment for further enhancing the crystallinity. Heat treatment is 2000 ℃
The heating is preferably performed at the above temperature, more preferably 2500 ° C. or higher, still more preferably 2800 ° C. or higher. By performing such mechanical energy treatment, the graphite particles or the carbonaceous particles remain coarse as a whole in the vicinity of the surface of the particles while maintaining the high crystallinity, and the particles having the distortion and the edge surface exposed. Become. This increases the number of surfaces where lithium ions can move in and out, resulting in high capacity even at high current densities.

The crystallinity of the grains and the roughness of the grain surface, that is, the amount of the edge planes of the crystals, is used as an index of the crystal plane of the (002) plane by the wide angle X-ray diffraction method (d002), the crystallite size (Lc), and it can be used an R value which is the peak intensity ratio of 1360 cm ^-1 to the peak intensity of 1580 cm ^-1 in the argon ion laser Raman spectrum. Generally, the carbon material has a (002) plane spacing (d
The smaller the value of 002) and the larger the crystallite size (Lc), the smaller the R value. That is, the graphite particles or the entire carbonaceous particles are in substantially the same crystal state. On the other hand, in the carbon material for electrodes of the present invention, the value of the interplanar spacing (d002) of the (002) plane is small and the crystallite size (Lc) is large, but the R value is large. That is, although the crystallinity of the bulk of the carbon material is high, the crystallinity in the vicinity of the surface of the carbon particles (from the particle surface to about 100 Å) is disturbed, and the exposure of the edge surface is increased. This mechanical energy treatment also introduces roundness into the particles,
The filling property of these particles can be improved.

It is known that in order to improve the filling property of the powder particles, it is preferable to fill the smaller particles that can enter the voids formed between the particles. Therefore, it is conceivable that the carbonaceous or graphite particles may be subjected to a treatment such as pulverization to reduce the particle size to improve the packing property. On the contrary, the filling property is rather lowered. It is considered that this is because the particle shape becomes more amorphous by crushing.

On the other hand, the larger the number of particles (coordination number n) in contact with one particle (particle of interest) in the powder particle group, the lower the proportion of voids in the filling layer. That is,
As a factor that affects the filling rate, the particle size ratio and composition ratio, that is, the particle size distribution is important. However, this study was carried out with a model spherical particle group, the carbonaceous or graphitic particles before the treatment handled in the present invention are scale-like, scale-like, plate-like, and are simply general Even if an attempt is made to increase the packing rate by controlling the particle size distribution only by crushing, classifying, etc., it is not possible to produce such a high packing state.

Generally, the scale-like, scale-like, or plate-like carbonaceous or graphite particles tend to deteriorate in packing property as the particle size becomes smaller. This is because the particles become more amorphous by crushing, and the number of protrusions such as "scratch", "peeling", and "bending" is increased on the surface of the particles, and more minute particles are formed on the particle surface. It is considered that this is because the irregular particles are attached to each other with a certain level of strength and the resistance between adjacent particles is increased to deteriorate the filling property.
If these irregular shapes are reduced and the particle shape is close to a spherical shape, the decrease in packing property is small even if the particle size is small.Theoretically, the same degree can be obtained for both large particle size carbon powder and small particle size carbon. It should indicate tap density.

According to the studies made by the present inventors, it has been confirmed that, in the case of carbonaceous or graphitic particles having substantially the same true density and substantially the same average particle diameter, the more spherical the shape, the higher the tap density. There is. That is, it is important to make the shape of the particles round and to approximate the shape of the particles. When the particle shape approaches a spherical shape, the filling property of the powder is also greatly improved. In the present invention, for the above reason, the tap density of the powder is used as the index of the sphericity. When the packing property of the powder or granules after the treatment is higher than that before the treatment, it can be considered that the particles are spherical due to the treatment method used. Further, in the method of the present invention, the tap density of the carbon material obtained when the treatment is carried out while significantly reducing the particle size is a higher value than the tap density of the carbon material of the same particle size obtained by general pulverization. If so, it can be considered that the result is spherical.

In the present invention, it is also possible to use carbonaceous or graphite particles which have been subjected to mechanical energy treatment and then classified to remove fine powder and / or coarse particles. A known method can be used for classification. By performing the above process, R value is the peak intensity ratio of 1360 cm ^-1 to the peak intensity of 1580 cm ^-1 in the argon ion laser Raman spectrum is 0.0
1 to 0.25, a raw graphite powder having a (002) plane spacing (d002) of less than 0.337 nm and a crystallite size (Lc) of 90 nm or more by a wide-angle X-ray diffraction method was subjected to mechanical energy treatment. the by performing an argon ion laser R value is the peak intensity ratio of 1360 cm ^-1 to the peak intensity of 1580 cm ^-1 in the Raman spectrum is more than 1.5 times the R value of the graphite powder before treatment, preferably at least 2-fold The upper limit is not particularly limited, but usually 10 times or less, preferably 7 times or less can be adopted, and the interplanar spacing (d002) of the (002) plane by the wide angle X-ray diffraction method is 0.337 n.
less than m, the crystallite size (Lc) is 90 nm or more,
Moreover, a carbon material for electrodes, which is a treated graphite powder having a tap density of 0.75 g / cm ³ or more, can be provided.

Multi- Layered Carbon Material for Electrodes The multi-layered carbon material for electrodes of the present invention is prepared by mixing the organic compound carbonized by the firing step with the carbon material for electrodes of the present invention having the above characteristics. It can be prepared by firing carbonization of an organic compound. The type of the organic compound mixed with the electrode carbon material is not particularly limited as long as it is carbonized by firing.
Therefore, it may be an organic compound that advances carbonization in a liquid phase or an organic compound that advances carbonization in a solid phase. The organic compound mixed with the electrode carbon material may be a single organic compound or a mixture of plural kinds of organic compounds.

As an organic compound for promoting carbonization in the liquid phase, coal tar pitch from soft pitch to hard pitch,
Heavy petroleum oil such as liquefied petroleum, heavy oil direct current such as asphaltene, heavy oil such as naphtha tar produced as a by-product during thermal decomposition of crude oil, naphtha, etc. Heat-treated pitches such as ethylene tar pitch, FCC decant oil, and Ashland pitch obtained by heat-treating oil can be used. Furthermore, polyvinyl chloride, polyvinyl acetate, polyvinyl butyral,
Vinyl polymers such as polyvinyl alcohol and substituted phenol resins such as 3-methylphenol formaldehyde resin and 3,5-dimethylphenol formaldehyde resin, aromatic hydrocarbons such as acenaphthylene, decacyclene and anthracene, and nitrogen ring compounds such as phenazine and acridine. , And substances such as sulfur ring compounds such as thiophene.

As the organic compound for promoting carbonization in the solid phase, natural polymers such as cellulose, chain vinyl resins such as polyvinylidene chloride and polyacrylonitrile, aromatic polymers such as polyphenylene, and furfuryl alcohol resins. , Phenol-formaldehyde resin,
Examples thereof include thermosetting resins such as imide resins and thermosetting resin raw materials such as furfuryl alcohol. Further, these organic compounds can be used by adhering to the surface of the powder particles by appropriately selecting a solvent and dissolving and diluting them, if necessary. As a method for producing the multilayer carbon material for an electrode of the present invention from these organic compounds and the carbon material for an electrode, a typical production method including the following steps can be exemplified.

(Step 1) A step of mixing the electrode carbon material and the organic compound together with a solvent, if necessary, by using various commercially available mixers, kneaders and the like to obtain a mixture. (Second Step) (Step Performed as Necessary) A step of heating the mixture as it is or with stirring as necessary to obtain an intermediate substance from which the solvent is removed. (Third step) A step of obtaining the carbonized substance by heating the mixture or the intermediate substance to 500 to 3000 ° C. under an atmosphere of an inert gas such as nitrogen gas, carbon dioxide gas, argon gas or the like or a non-oxidizing atmosphere. (Fourth step) (Step to be carried out if necessary) A step of pulverizing, crushing, classifying, etc., the carbonized substance to be powder-processed.

A solvent may or may not be used in the mixing in the first step. When a solvent is used, the type and amount thereof are not particularly limited, but a solvent that dissolves the organic compound used or reduces the viscosity is preferable. The temperature at the time of mixing is not particularly limited, but is, for example, room temperature to 300 ° C. or lower, preferably room temperature to 200 ° C.
C. or lower, more preferably from room temperature to 100.degree. C. or lower is used. In the first step, the organic compound can be attached to the surface of the powder particles of the electrode carbon material by mixing the organic compound and the electrode carbon material. The heating temperature in the second step is usually 300 ° C or higher, preferably 400 ° C.
Or higher, more preferably 500 ° C. or higher, and the upper limit is not particularly limited, but 3000 ° C. or lower, preferably 2800 ° C.
Hereafter, it is more preferably 2500 ° C. or lower, and particularly preferably 1500 ° C. or lower. Although the second step can be omitted, usually, the third step is performed after the second step is performed to obtain an intermediate substance.

In the heat treatment of the third step, the heat history temperature condition is important. The lower limit temperature is usually 500 ° C. or higher, preferably 700 ° C. or higher, more preferably 900 ° C. or higher, although it depends on the type of organic compound and heat history. The upper limit temperature is usually 3000 ° C. or lower, preferably 280
It is 0 ° C or lower, more preferably 2500 ° C or lower, and particularly preferably 1500 ° C or lower. The rate of temperature increase, the rate of cooling, the heat treatment time, etc. can be arbitrarily set according to the purpose. Also, after heat treatment in a relatively low temperature region, the temperature can be raised to a predetermined temperature. The fourth step is a step of pulverizing, crushing, sieving, and the like for powder processing, if necessary, but it can be omitted. In addition, the fourth step can be performed before the third step, or both before and after the third step. The reactor used in these steps may be a batch type or a continuous type. Further, it may be a single unit or a plurality of units.

In the multilayer carbon material for electrodes of the present invention
Percentage of carbonaceous materials derived from organic compounds (hereinafter referred to as "coverage")
U) is usually 0.1 to 50% by weight, preferably 0.5 to 2
5% by weight, more preferably 1 to 15% by weight, still more preferably
The amount is adjusted to be 2 to 10% by weight. Also books
The multi-layered carbon material for electrodes of the invention has a volume-based average particle size of
2 to 70 μm, preferably 4 to 40 μm, more preferably
Is 5 to 35 μm, more preferably 7 to 30 μm.
It The specific surface area measured using the BET method is, for example, 0.1
-10m ²/ G, preferably 1-10 m²/ G, more preferred
1-7m²/ G, particularly preferably 1 to 4 m²/ G
is there. Further, the multilayer carbon material for electrodes of the present invention is C
In the diffraction pattern of X-ray wide-angle diffraction using the uKα ray as the source,
Exceeding the crystallinity of the carbonaceous or graphitic particles that form the core
Preferably not.

The multi-layered carbon material for an electrode of the present invention has a Raman spectrum of 1580 to 1620 cm in Raman spectrum analysis using an argon ion laser beam having a wavelength of 5145 cm ^-1.
Peak PB appearing in the range of 1350 ^-1 to the peak PA (peak intensity IA) that appears in the range of ^-1
The R value represented by the ratio "IB / IA" of (peak intensity IB) is preferably 0.1 to 0.7, more preferably 0.20 to 0.7, and particularly preferably 0.25 to 0.6. Is. The tap density is 0.70 to 1.40 g / cm.
³ , preferably 0.75 to 1.40 g / cm ³ , and more preferably 0.85 to 1.40 g / cm ³ . The multi-layer structure may further improve the tap density of the carbon material for electrodes, and may have the effect of introducing roundness into the shape. The electrode carbon material of the present invention has a rough particle surface,
When used in the multi-layered carbon material for an electrode of the present invention, an effect of enhancing the binding property with the coated carbonaceous material can be expected.

Electrode An electrode can be produced using the carbon material for an electrode or the carbon material having a multilayer structure for an electrode of the present invention. In particular, the multi-layer structure carbon material for electrodes of the present invention can be very preferably used for manufacturing electrodes. The manufacturing method is not particularly limited, and it can be manufactured according to a generally used method. As a typical method, a binder, a solvent, or the like is added to a carbon material for an electrode or a multilayer carbon material for an electrode to form a slurry, and the obtained slurry is applied to a substrate of a metal current collector such as a copper foil. The method of applying and drying can be mentioned. Also, the packing density of the electrode plate is improved by increasing the packing density of the electrode plate by increasing the packing density of the electrode plate by consolidating the carbon material for electrodes or the multi-layer structure carbon material for electrodes applied and dried with a roll press, compression molding machine, etc. Can be made. Further, the carbon material for electrodes or the multi-layered carbon material for electrodes can be molded into the shape of electrodes by a method such as compression molding.

Binders that can be used in the production of electrodes include solvent-stable resin polymers such as polyethylene, polypropylene, polyethylene terephthalate, aromatic polyamide and cellulose, styrene-butadiene rubber and isoprene rubber. , Butadiene rubber, ethylene
Rubber-like polymers such as propylene rubber, styrene / butadiene / styrene block copolymers, hydrogenated products thereof, styrene / ethylene / butadiene / styrene copolymers, styrene / isoprene / styrene block copolymers, hydrogenated products thereof Such as thermoplastic elastomeric polymer, syndiotactic 1,2-polybutadiene, ethylene / vinyl acetate copolymer, propylene / α-olefin (C2-12) copolymer, etc. Fluorine-based polymers such as vinylidene fluoride, vinylidene fluoride / hexachloropropylene copolymer, polytetrafluoroethylene, polytetrafluoroethylene / ethylene copolymer, and the like, and a polymer composition having lithium ion ionic conductivity Things can also be mentioned.

Examples of the polymer having ion conductivity include polyether polymer compounds such as polyethylene oxide and polypropylene oxide, cross-linked polymer of polyether compound, polyepichlorohydrin, polyphosphazene, polysiloxane, polyvinylpyrrolidone and polyvinylidene. A system in which a polymer compound such as carbonate or polyacrylonitrile is combined with a lithium salt or an alkali metal salt mainly containing lithium, or an organic compound having a high dielectric constant such as propylene carbonate, ethylene carbonate or γ-butyrolactone It is possible to use a system in which a low-viscosity organic compound such as a linear carbonate is mixed. The ionic conductivity of such an ion conductive polymer composition at room temperature is preferably 10 ^-5 s / cm or more, more preferably 10 ^-3 s / cm or more.

Various forms can be adopted as a mixing form of the carbon material for electrodes or the carbon material having a multilayer structure for electrodes and the binder. For example, a form in which both particles are mixed, a form in which a fibrous binder is mixed in a form in which the carbonaceous material particles are entangled with each other, or a form in which a layer of the binder is attached to the particle surface of the carbonaceous material is mentioned. it can. The mixing ratio of the two is preferably 0.1 to 30% by weight of the binder with respect to the carbon material for electrodes or the multi-layer structure carbon material for electrodes, and 0.5.
More preferably, it is set to 10% by weight. If 30% by weight or more of the binder is added, the internal resistance of the electrode increases, and conversely, if 0.1% by weight or less, the binding property between the current collector and the carbon material for the electrode or the multilayer carbon material for the electrode is poor. There is a tendency.

The density of the active material layer on the electrode, which is compacted by performing roll pressing, compression molding, or the like, in the electrode made of the carbon material for an electrode or the carbon material for a multi-layer structure of the present invention (hereinafter referred to as electrode density) ) 0.5-1.7 g / c
m ³ , preferably 0.7 to 1.6 g / cm ³ , and more preferably 0.7 to 1.55 g / cm ³ , the capacity per unit volume of the battery without impairing high efficiency discharge and low temperature characteristics. You will be able to bring out the maximum. At this time, the carbon material for an electrode or the carbon material for a multi-layer structure carbon material for an electrode of the present invention has a high charge / discharge capacity due to the high crystallinity inside the particle, and the surface of the particle is rough, that is, the surface of the particle is an edge. The particle shape is such that the part is exposed or the amount of the edge portion increases (the thickness direction in the particle becomes relatively thick by crushing in the direction perpendicular to the plane of the plate-like particle,
That is, the particle shape having a larger proportion of the edge portion) increases the area where lithium ions are doped or dedoped into the carbon material for electrode or the carbon material for multi-layer structure carbon material for electrode. In addition, it is considered that the high tap density, that is, the carbon material having a nearly spherical shape does not close the voids in the electrode, and thus the lithium ions can be diffused more smoothly.

Secondary Battery The carbon material for electrodes and the multi-layered carbon material for electrodes of the present invention are useful as electrodes for batteries. In particular, it is extremely useful as a negative electrode material for non-aqueous secondary batteries such as lithium secondary batteries. For example, a non-aqueous secondary battery formed by combining an organic electrolyte mainly composed of a metal chalcogenide-based positive electrode and a carbonate-based solvent for a commonly used lithium-ion battery with a negative electrode manufactured according to the above method has a large capacity. The irreversible capacity observed in the initial cycle is small, the rapid charge / discharge capacity is high, and the cycle characteristics are excellent.
The storage stability and reliability of the battery when left at high temperature are also high, and it is extremely excellent in high-efficiency discharge characteristics and discharge characteristics at low temperatures. There are no particular restrictions on the selection of the members such as the positive electrode and the electrolytic solution that compose such a non-aqueous secondary battery in terms of battery configuration. In the following, materials and the like of members constituting the non-aqueous secondary battery will be exemplified, but materials that can be used are not limited to these specific examples.

For the positive electrode constituting the non-aqueous secondary battery of the present invention, for example, a lithium transition metal composite oxide material such as lithium cobalt oxide, lithium nickel oxide or lithium manganese oxide; a transition metal such as manganese dioxide. Oxide material: A material capable of inserting and extracting lithium such as a carbonaceous material such as fluorinated graphite can be used. Specifically, LiFeO ₂ , LiCoO ₂ , LiNiO ₂ , LiM
n ₂ O ₄ and non-stoichiometric compounds thereof, MnO ₂ , Ti
_{S 2, FeS 2, Nb 3} S 4, Mo 3 S 4, CoS 2, V
₂ O ₅ , P ₂ O ₅ , CrO ₃ , V ₃ O ₃ , TeO ₂ , GeO ₂ or the like can be used. The method for manufacturing the positive electrode is not particularly limited, and the positive electrode can be manufactured by the same method as the above-described method for manufacturing the electrode.

For the positive electrode current collector used in the present invention, it is preferable to use a valve metal or an alloy thereof which forms a passivation film on the surface by anodic oxidation in an electrolytic solution. Examples of the valve metal include metals belonging to the group IIIa, IVa and Va (groups 3B, 4B and 5B) and alloys thereof. Specific examples include Al, Ti, Zr, Hf, Nb, Ta, and alloys containing these metals.
1, Ti, Ta and alloys containing these metals can be preferably used. In particular, Al and its alloys are lightweight and therefore desirable because of their high energy density.

As the electrolytic solution used in the non-aqueous secondary battery of the present invention, a solution in which a solute (electrolyte) is dissolved in a non-aqueous solvent can be used. As the solute, an alkali metal salt or a quaternary ammonium salt can be used. Specifically, LiClO ₄ , LiPF ₆ , LiBF ₄ , LiC
F ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiN (CF ₃ CF
₂ SO ₂ ) ₂ , LiN (CF ₃ SO ₂ ) (C ₄ F ₉ SO ₂ ), L
It is preferable to use one or more compounds selected from the group consisting of iC (CF ₃ SO ₂ ) ₃ .

As the non-aqueous solvent, ethylene carbonate, propylene carbonate, butylene carbonate,
Cyclic carbonates such as vinylene carbonate, cyclic ester compounds such as γ-butyrolactone; chain ethers such as 1,2-dimethoxyethane; crown ethers, 2-
Cyclic ethers such as methyltetrahydrofuran, 1,2-dimethyltetrahydrofuran, 1,3-dioxolane and tetrahydrofuran; chain carbonates such as diethyl carbonate, ethylmethyl carbonate and dimethyl carbonate can be used. As the solute and the solvent, one kind may be selected and used, or two or more kinds may be mixed and used. Among these, the non-aqueous solvent preferably contains a cyclic carbonate and a chain carbonate.

The material and shape of the separator used in the non-aqueous secondary battery of the present invention are not particularly limited. The separator separates the positive electrode and the negative electrode so that they do not come into physical contact with each other, and preferably has high ion permeability and low electric resistance. The separator is preferably selected from materials that are stable with respect to the electrolytic solution and have excellent liquid retention. Specifically, using a porous sheet or non-woven fabric made of polyolefin such as polyethylene and polypropylene as a raw material,
The electrolytic solution can be impregnated.

The method for producing the non-aqueous electrolyte secondary battery of the present invention having at least the non-aqueous electrolyte solution, the negative electrode and the positive electrode is not particularly limited and can be appropriately selected from the methods usually employed. In the non-aqueous electrolyte secondary battery of the present invention, in addition to the non-aqueous electrolyte, the negative electrode and the positive electrode, an outer can, a separator, a gasket, a sealing plate, a cell case and the like can be used as required. The manufacturing method, for example, put the negative electrode on the outer can, provide an electrolyte and a separator on it,
Further, the positive electrode may be placed so as to face the negative electrode and caulked together with the gasket and the sealing plate to form a battery. The shape of the battery is not particularly limited, and may be a cylinder type in which the sheet electrode and the separator are spiral, a cylinder type in which the pellet electrode and the separator are combined with each other, or a coin type in which the pellet electrode and the separator are stacked. .

[0061]

EXAMPLES The present invention will be described in more detail with reference to specific examples. Materials, usage amounts, ratios shown in the following specific examples,
The operation and the like can be appropriately changed without departing from the spirit of the present invention. Therefore, the scope of the present invention is not limited to the specific examples shown below.

Example 1 18 kinds of carbon materials for electrodes were prepared by treating a predetermined amount of graphite raw material shown in Table 1 under the treatment conditions shown in Table 1. The types of graphite raw materials used as raw materials are as shown in Table 3. Table 1 shows the results of measuring the physical properties of the 18 kinds of prepared carbon materials for electrodes by the measuring methods described below.

[0063]

[Table 1]

(Example 2) Carbon material 3 shown in Table 2
kg and 1 kg of petroleum tar are M produced by Matsubo Co., Ltd.
The mixture was put into a 20 type Ledige mixer (internal volume: 20 liters) and kneaded. Then, 700 in a nitrogen atmosphere
After the temperature was raised to 0 ° C. for detarring treatment, the temperature was raised to 1300 ° C. for heat treatment. The obtained heat-treated product was crushed with a pin mill and classified for the purpose of removing coarse particles, and finally 13 kinds of multilayer carbon materials for electrodes were prepared. Table 2 shows the results of measuring the physical properties of the prepared 13 types of multi-layer structure carbon materials for electrodes by the measurement methods described below.

[0065]

[Table 2]

Details of the graphite materials used in Examples 1 and 2 are shown in Table 3 below.

[0067]

[Table 3]

The methods for measuring the physical properties of the carbon materials prepared in Examples 1 and 2 are shown below. (1) About 15% of X-ray standard high-purity silicon powder was added to and mixed with a carbon material for an X-ray diffraction electrode, and the obtained mixture was packed in a sample cell,
A wide-angle X-ray diffraction curve was measured by a reflection diffractometer method using CuKα rays monochromatized by a graphite monochromator as a radiation source, and the surface spacing (d0
02) and crystallite size (Lc) were determined. (2) Raman analysis Raman spectrum analysis was performed using NR-1800 manufactured by JASCO Corporation. The analysis was performed using an argon ion laser beam having a wavelength of 514.5 nm, the laser power set to 30 mW, and the exposure time set to 75 seconds. The laser power is 30 mW in the light source part, and 18 m in the measurement sample part due to the laser light attenuation in the optical path between the light source sample parts.
It was W. The sample was filled in the measurement cell by spontaneously dropping the carbon material for an electrode, and the measurement was performed while irradiating the sample surface in the cell with laser light and rotating the cell in a plane perpendicular to the laser light. Intensity IA of peak PA near 1580 cm ⁻¹ in the obtained Raman spectrum,
The intensity IB of the peak PB near 1360 cm ⁻¹ is measured,
The intensity ratio (R = IB / IA) and the half width of the peak near 1580 cm ^-1 were measured. Further, the area of the peak PA around the 1580 cm ^-1 (integrated value of 1480~1680cm ^-1) YA, (integral value of 1260~1460cm ^-1) area of the peak PB around the 1360 cm ^-1 to the YB, its The area ratio value G = YA / YB was measured.

(3) Tap Density Using a powder density measuring device (Tap Denser KYT-3000 manufactured by Seishin Enterprise Co., Ltd.), a sieve having an opening of 300 μm is used as a sieve through which the carbon material for electrodes permeates, and 20 cm ³
After the powder was dropped into the tap cell of (1) to fill the cell fully, tapping with a stroke length of 10 mm was performed 1000 times, and the tap density at that time was measured. (4) The true density was measured by a liquid phase substitution method using a pycnometer using a 0.1% aqueous surfactant solution. (5) BET Specific Surface Area Using an AMS-8000 manufactured by Okura Riken Co., Ltd., the sample was heated to 350 ° C. for preliminary drying, and after flowing nitrogen gas for 15 minutes, it was measured by the BET one-point method by nitrogen gas adsorption. (6) Average particle size A 2% by volume aqueous solution of polyoxyethylene (20) sorbitan monolaurate (about 1 ml), which is a surfactant, is mixed with a carbon material for an electrode, and ion-exchanged water is used as a dispersion medium in a laser diffraction particle size. Distributor (LA-700 manufactured by HORIBA, Ltd.)
The volume-based average particle diameter (median diameter) was measured by.

(7) Average circularity flow type particle image analyzer (FPIA- manufactured by Toa Medical Electronics Co., Ltd.)
2000) was used to measure the particle size distribution by the equivalent circle diameter and calculate the circularity. Ion-exchanged water was used as the dispersion medium, and polyoxyethylene (2
0) Sorbitan monolaurate was used. The equivalent circle diameter is a circle that has the same projected area as the captured particle image (equivalent circle)
The circularity is the ratio of the perimeter of the equivalent circle as the numerator and the perimeter of the captured particle projection image as the denominator. The circularity of all measured particles was averaged to obtain the average circularity.

(8) Coverage of multi-layered carbon material The coverage of the multi-layer structure carbon material was obtained from the following equation.

[Formula 3] Coverage (% by weight) = 100− (K × D) / (N
× (K + T)) × 100 In the above formula, K is the weight of the carbon material (kg), T is the weight of petroleum tar (kg), and D is the weight (kg) of the kneaded product before detarring (second step). ) And N represent the recovered amount (kg) of the heat-treated product after the heat treatment (third step).

Example 3 A semi-electrostatic field was prepared using the prepared carbon material, and the charge / discharge property was tested. (1) Preparation of Half Battery A dimethylacetamide solution of polyvinylidene fluoride (PVdF) was added to 5 g of the carbon material in an amount of 10% by weight in terms of solid content, and the mixture was stirred to obtain a slurry. This slurry was applied on a copper foil by the doctor blade method and pre-dried at 80 ° C. Furthermore, after consolidating with a roll press so that the electrode density is 1.4 g / cm ³ or 1.5 g / cm ³ , it is punched into a disk shape with a diameter of 12.5 mm and dried under reduced pressure at 110 ° C. to form an electrode. And Then, a coin cell in which an electrode and a lithium metal electrode were opposed to each other centering on a separator impregnated with an electrolytic solution was prepared and a charge / discharge test was conducted. The electrolytic solution used was a solvent prepared by mixing ethylene carbonate and diethyl carbonate at a weight ratio of 2: 8 and dissolving lithium perchlorate at a ratio of 1.5 mol / liter.

(2) Measurement of irreversible capacity Charging (doping lithium ion into the electrode) at 0V with a current density of 0.16 mA / cm ² was carried out, and then the current density of 0.
The value obtained by subtracting the first-time discharge capacity from the first-time charge capacity at the time of discharging at 33 mA / cm ² to 1.5 V (lithium ion dedoping from the electrode) was defined as the irreversible capacity. (3) discharge capacity and discharge rate property (quick discharging characteristics) of the measured current density 0.16 mA / cm charging to 0V at ² and current density 0.33 mA / cm ² 3 times the discharge to 1.5V at Repeatedly, the discharge capacity of the third time at that time was defined as "discharge capacity". Next, charge the battery with a current density of 0.16 mA / c
m ^{2 up} to 0 V, each discharge current density 2.8 m
A / cm ^2, carried out at 5.0 mA / cm ² until 1.5V, and the discharge capacity obtained capacity at each current density 2.8 mA / cm ² and 5.0 mA / cm ^2, an indication of rapid discharge characteristics And The results of these tests are summarized in Table 4 below.

[0074]

[Table 4]

(Example 4) Carbon material for electrode No. prepared in Example 1 11, using Seishin Enterprise Co., Ltd.'s wind power classifier "MC-100" under the conditions of removing 25% by weight of fine powder and 22% by weight of coarse powder, respectively, and the average particle size after classification. Diameter = 20.8 μm, d002 = 0.
336 nm, BET specific surface area = 5.3 m ² / g, tap density = 0.82 g / cm ³ , Lc> 100 nm, true density = 2.26 g / cm ³ , Raman R value = 0.25, Raman 1580 half width = A carbon material for electrodes having a physical property of 22.0 cm ^-1 was obtained. Next, an experiment was performed in the same manner as in Example 2 except that this carbon material for electrodes was used to obtain a multilayer carbon material for electrodes having the following physical properties. Raman R value =
0.37, Raman 1580 full width at half maximum = 29.5 cm ⁻¹ , tap density = 0.99 g / cm ³ , BET specific surface area = 2.
3 m ² / g, average particle size = 24.6 μm, coverage = 4.9
weight%. A half cell was prepared in the same manner as in Example 3 except that the multi-layered carbon material obtained above was used, and the charge / discharge property was tested. As a result, electrode density = 1.5 g / c
m ³ , initial irreversible capacity = 17 mAh / g, 0.33 A /
cm ³ Discharge capacity = 352 mAh / g, 2.8 mA / cm ³
Rapid discharge capacity = 351 mAh / g, 5.0 mA / cm ³
Rapid discharge capacity = 334 mAh / g, which was a good characteristic.

[0076]

EFFECT OF THE INVENTION A battery using the carbon material for electrodes of the present invention or the carbon material for multilayer structure for electrodes has a capacity (0.33 m).
A / cm ³ discharge volume) is large, it has the feature that the irreversible capacity observed in the initial cycle is small, is excellent capacity retention rate cycle. More particularly rapid charge and discharge,
(5.0 mA / cm ³ rapid discharge capacity) is greatly improved. In addition, the battery has high storage stability and reliability when left at high temperature, and has excellent discharge characteristics at low temperature. Therefore, the carbon material for electrodes and the carbon material having a multi-layer structure of the present invention can be effectively used for manufacturing batteries such as lithium batteries.

Continuation of the front page (56) Reference JP-A-10-334915 (JP, A) JP-A-11-54123 (JP, A) JP-A-11-45715 (JP, A) (58) Fields investigated (Int .Cl. ⁷ , DB name) H01M 4/58 H01M 4/02 H01M 10/40

Claims (14)

(57) [Claims] 1. A wide-angle X-ray diffraction method is used to measure a (002) plane spacing (d002) of less than 0.337 nm, a crystallite size (Lc) of 90 nm or more, and a peak intensity of 1580 cm ⁻¹ in an argon ion laser Raman spectrum. The R value, which is the peak intensity ratio at 1360 cm ^-1 , is 0.2.
A carbon material for an electrode, which has a tap density of 0 or more and 0.77 g / cm ³ or more. 2. The carbon material for an electrode according to claim 1, which has a true density of 2.21 g / cm ³ or more. 3. The carbon material for an electrode according to claim 1, which has a BET specific surface area of less than 18 m ² / g. 4. The carbon material for an electrode according to claim 1, which has an average particle size of 2 to 50 μm. 5. The full width at half maximum of the peak at 1580 cm ^-1 in the argon ion laser Raman spectrum is 20 cm.
^-1 or more, The carbon material for electrodes according to any one of claims 1 to 4, characterized in that it is ^-1 or more. 6. The particle size is reduced so that the average particle size ratio before and after the treatment is 1 or less, and the tap density is increased by the treatment.
And, in the argon ion laser Raman spectrum, 1360 cm with respect to the peak intensity of 1580 cm ^-1.
The carbon material for an electrode according to any one of claims 1 to 5, wherein the mechanical energy treatment is performed so that the R value, which is the peak intensity ratio of ^-1 , becomes 1.5 times or more by the treatment. Method. 7. The carbon for an electrode according to claim 6, wherein the mechanical energy treatment is performed by using a device having a rotor having a large number of blades installed inside a casing and rotating the rotor at a high speed. Material manufacturing method. 8. A multilayer carbon material for electrodes, which is produced by mixing the carbon material according to claim 1 with an organic compound and then carbonizing the organic compound. 9. In a Raman spectrum analysis using an argon ion laser beam having a wavelength of 5145 cm ⁻¹ , 15
^{1 for} the peak appearing in the range of 80 to 1620 cm ^-1
The R value represented by the ratio of peaks appearing in the range of 350 to 1370 cm ⁻¹ is 0.20 or more, and the tap density is
It is 0.85 g / cm ³ or more , and the multi-layered structure carbon material for electrodes according to claim 8. 10. The multi-layered carbon material for electrodes according to claim 8, wherein the BET specific surface area is 10 m ² / g or less and the volume-based average particle diameter is 2 to 70 μm. . 11. A non-aqueous secondary battery using the carbon material for an electrode according to any one of claims 1 to 5 and / or the carbon material for a multilayer structure for an electrode according to any one of claims 8 to 10. electrode. 12. A non-aqueous electrolyte secondary battery having a negative electrode containing a carbonaceous material capable of inserting and extracting lithium, a positive electrode, and a non-aqueous electrolyte containing a solute and a non-aqueous solvent, wherein the carbon is A non-aqueous secondary battery, wherein the quality material is the carbon material for an electrode according to any one of claims 1 to 5 or the carbon material for a multilayer structure for an electrode according to any one of claims 8 to 10. 13. The solute is LiClO ₄ , LiP
F ₆ , LiBF ₄ , LiCF ₃ SO ₃ , LiN (CF ₃ S
O ₂ ) ₂ , LiN (CF ₃ CF ₂ SO ₂ ) ₂ , LiN (CF ₃
The non-aqueous secondary battery according to claim 12, which is one or more compounds selected from the group consisting of SO ₂ ) (C ₄ F ₉ SO ₂ ), LiC (CF ₃ SO ₂ ) ₃ . 14. The non-aqueous secondary battery according to claim 12, wherein the non-aqueous solvent contains a cyclic carbonate and a chain carbonate.