JPH05307959A - Electrode material and manufacturing method thereof - Google Patents

Abstract

(57) [Summary] [Purpose] Large capacity, excellent charge-discharge cycle characteristics,
Provided is a negative electrode which enables a highly safe secondary battery with less self-discharge. [Structure] An electrode material mainly composed of a multiphase carbonaceous material (M) having the following characteristics (a), (b), (c) and (d): (b) H / C atomic ratio is 0 (B) True density and G, which is the ratio of the integrated intensities of the spectra of two specific peaks by Raman spectrum analysis, satisfy a specific relational expression; (c) By wide-angle X-ray diffraction It has at least one peak with an interplanar spacing d ₀₀₂ of less than 3.40Å; (d) A specific surface area of 20 m ² / g or less.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an electrode material. More specifically, the present invention relates to an electrode material useful as an electrode for secondary batteries. Further, the present invention relates to an electrode material which has a high capacity, is excellent in long-term charge / discharge cycle characteristics, is free from self-discharge, and enables a highly safe secondary battery.

[0002]

2. Description of the Related Art In recent years, there has been a great deal of research and development aimed at improving the performance of batteries. One of them is research on a rechargeable secondary battery using electrochemical doping with a carbon material as an electrode. When graphite is used as the negative electrode for the carbon electrode, cations such as Li ⁺ ions can be doped between the layers, but it is extremely unstable in the electrolytic solution and reacts with the electrolytic solution to form an electrode material. (J. Electrochem. Society.125, 687 (1978),). On the other hand, using a conductive polymer such as polyacetylene as an electrode,
There is also great interest in researching rechargeable secondary batteries using electrochemical doping. For example
57-121168 proposes a battery using an acetylene polymer. However, polyacetylene is unstable, such as being oxidatively deteriorated in the air, and is deteriorated by reacting with a small amount of water or oxygen contained in the solvent, resulting in poor stability as an electrode. In particular, the polyacetylene used as the negative electrode is severely deteriorated in the electrolytic solution. Therefore, a battery using polyacetylene for both electrodes has a strong self-discharge, and the charge / discharge charge efficiency is poor, and it is difficult to obtain a high-performance and highly reliable battery.

In a battery using Li metal as the negative electrode and polyacetylene as the positive electrode, problems such as charge efficiency in charging and discharging are improved as compared with the battery using polyacetylene in both electrodes. However, the charge / discharge cycle characteristics are extremely poor. That is, when the battery is discharged, Li becomes Li ions from the negative electrode body and moves into the electrolytic solution, and at the time of charging, this Li ion becomes metallic Li and is electrodeposited again on the negative electrode body, but this charge / discharge cycle is repeated. And metal Li that is electrodeposited accordingly
Is to be dendrite-like. Since this dendrite-like Li is an extremely active substance, it decomposes the electrolytic solution, resulting in the disadvantage that the charge / discharge cycle characteristics of the battery deteriorate. As this grows further,
Finally, there arises a problem that the dendrite-like metal Li electrodeposit penetrates the separator and reaches the positive electrode body to cause a short circuit phenomenon. In other words, there arises a problem that the charge / discharge cycle life is short. In addition, the conductive polymer has a drawback that it lacks lithium ion doping amount, that is, electrode capacity and stable charge / discharge characteristics. In order to avoid such a problem, it has been attempted to use a carbonaceous material obtained by firing an organic compound as a carrier as a negative electrode and to support Li or an alkali metal mainly containing Li on the carrier. By using such a negative electrode body, the charge and discharge cycle characteristics of the negative electrode were dramatically improved, but on the other hand, this electrode capacity was not sufficiently large. Under such circumstances, an object of the present invention is to provide an electrode material for an electrode for a secondary battery, which has a large electrode capacity, is excellent in charge / discharge cycle characteristics, and has little self-discharge.

As a result of intensive studies to solve the above problems, the present inventor has found that an electrode material containing a specific carbonaceous material as a main component, which will be described later, is extremely effective for the above purpose. The present invention has been reached. That is, the present invention provides an electrode material mainly composed of particles or fibers of a multiphase carbonaceous material (M) having the following characteristics (a), (b), (c) and (d). .. (A) The H / C atomic ratio is 0.08 or less; (b) In the Raman spectrum analysis using an argon ion laser beam having a true density of ρ (g / cm ³ ) and a wavelength of 5145Å, the following (1) When the value represented by the formula is the G value, the ρ and the G value satisfy the conditions of the following formulas (2) to (4);

[0005]

[Equation 2]

2.03 ≦ ρ ≦ 2.26 (2) G ≧ 0.30 (3) G ≧ −1.50ρ + 3.50 (4) (c) Wide-angle X-ray diffraction The surface spacing d of the (002) plane according to
₀₀₂ has at least one peak less than 3.40Å; (d) The specific surface area is 20 m ² / g or less.

The present invention also has a true density of 2.15 g / cm ^3.
As described above, the surface spacing d of the (002) plane by the X-ray wide-angle diffraction method
₀₀₂ has a peak of less than 3.40Å and has a volume average particle size of 3
A carbonaceous material (A) consisting of particles of 5 μm or less or fibers having an average diameter of 20 μm or less is used as a core, and the surface of this carbonaceous material (A) is coated with an organic compound and then carbonized,
It forms a carbonaceous material (B) having d ₀₀₂ of 3.40 Å or more by the wide-angle diffraction method, and is 1 / of the specific surface area of the carbonaceous material (A) of the nucleus.
The present invention provides a method for producing the above-mentioned electrode material, which comprises particles or fibers of a multiphase carbonaceous material (M) having a specific surface area of 2 or less.

The present invention will be described in more detail below. The multiphase carbonaceous material (M) of the present invention is a multiphase carbonaceous material (A) that forms a nucleus and a carbonaceous material (B) that is a surface layer formed by coating the surface of this nucleus. It has been found that a material having a composite structure and having the above-mentioned unique physical properties is extremely useful as a material for the negative electrode of a secondary battery.

[Physical Properties of Multiphase Carbonaceous Material (M)] (H / C Atomic Ratio) The multiphase carbonaceous material (M) which is the negative electrode material according to the present invention has an H / C atomic ratio of 0.08 or less. , Preferably 0.07 or less, more preferably 0.06 or less, further preferably 0.05 or less, particularly preferably 0.04.
Hereafter, it is most preferably 0.03 or less. This H / C
The atomic ratio is given as an average value of the H / C atomic ratio of the entire carbonaceous material contained in the core and the multiphase composite structure covering the core.

(Relationship between true density and Raman spectrum analysis value) The true density (ρ) of the multiphase carbonaceous material (M) of the present invention is the total carbon contained in the multiphase composite structure including the surface layer and the nucleus. It is given as the average of the true densities of the material. Furthermore, the multiphase carbonaceous material (M) of the present invention has a true density of ρ (g / cm ³ ),
In a Raman spectrum analysis using an argon ion laser beam having a wavelength of 5145Å (also in the following Raman spectrum analysis, under this condition unless otherwise specified),
If the value expressed by the following equation (1) is the G value, ρ and G
The value satisfies the conditions of the following expressions (2) to (4).

[0011]

[Equation 3]

2.03 ≦ ρ ≦ 2.26 (2) G ≧ 0.30 (3) G ≧ −1.50ρ + 3.50 (4) Preferably, the following (2 ′) , (3 ′) and (4 ′) are satisfied. 2.05 ≦ ρ ≦ 2.24 (2 ′) G ≧ 0.35 (3 ′) G ≧ −1.50ρ + 3.55 (4 ′) More preferably, the following (2 "), (3") and (4 ")
The condition of the expression is satisfied. 2.08 ≦ ρ ≦ 2.22 (2 ″) G ≧ 0.40 (3 ″) G ≧ −1.50ρ + 3.60 (4 ″) More preferably, the following (2 The conditions of '″), (3 ′ ″) and (4 ′ ″) are satisfied: 2.10 ≦ ρ ≦ 2.21 (2 ′ ″) G ≧ 0.45 (3 ′ ″) G ≧ −1.50ρ + 3.65 (4 ′ ″) Particularly preferably, the following (2 ″ ″), (3 ″ ″) and (4 ″ ″) ) The condition is satisfied: 2.12 ≦ ρ ≦ 2.20 (2 ″ ″) 1.2 ≧ G ≧ 0.70 (3 ″ ″) G ≧ −1. 50ρ + 3.70 (4 ″ ″) Most preferably, the following (2 ′ ″ ″), (3 ′ ″ ″),
The condition of (4 ''''') is satisfied. 2.13 ≦ ρ ≦ 2.19 (2 ′ ″ ″) 1.1 ≧ G ≧ 0.55 (3 ′ ″ ″) G ≧ −1.50ρ + 3.75・ (4 ''''')

(Raman spectrum) The fine structure of the carbonaceous material (B) forming the surface layer mainly contributes to the Raman spectrum measured under the conditions of the present invention. That is,
Peak P _A , 1340 in the range of 1580 to 1620 cm ^-1
It has a peak P _{B in} the range of ˜1380 cm ⁻¹ . P _A is a peak observed corresponding to a crystal structure in which the spread of aromatic ring network planes is grown and formed in layers, and P _B is a peak corresponding to a disordered amorphous structure. Both peaks P _B and P _A
The ratio G = (I _B / I _A ) of the integrated intensities I _B and I _A of the spectra respectively corresponding to the carbonaceous material, that is, carbonaceous particles,
The larger the ratio of the amorphous structure portion in the surface layer such as carbonaceous fiber, the larger the value. That is, the position of P _A changes depending on the degree of perfection of the crystal part. The position of P _A of the carbonaceous material used in the present invention is 1580 as described above.
~ 1620 cm ^-1 , preferably 1585 to 162
0 cm ^-1, more preferably 1590~1620cm ^-1, more preferably 1595~1615cm ^-1, particularly preferably from 1600~1610cm ^-1. The full width at half maximum of the peak is narrower as the higher-order structure of the carbonaceous material (B) is more uniform. The half width at half maximum of P _A of the carbonaceous material used in the present invention is
Preferably 60 cm ^-1 or less, more preferably 8 cm ^-1 or more 6
0 cm ^-1 or less, more preferably 10～60Cm ^-1, particularly preferably 10~55cm ^-1. P _B is usually 136
It has a peak at 0 cm ^-1 . The full width at half maximum of P _B is preferably 20 cm ⁻¹ or more, more preferably 20 to 150 cm ⁻¹ , further preferably 25 to 125 cm ⁻¹ , particularly preferably 3 cm.
It is from 0 to 115 cm ^-1 , most preferably from 35 to 110 cm ^-1 .

(X-Ray Wide Angle Diffraction) Further, the multiphase carbonaceous material (M) constituting the electrode material of the present invention has a peak in the X-ray wide angle diffraction of the (002) plane spacing d ₀₀₂ of less than 3.40Å. .. It is preferably 3.35 Å or more and less than 3.40 Å, more preferably 3.35 Å or more and 3.39 Å or less, further preferably 3.36 Å or more and 3.39 Å or less, particularly preferably 3.36 Å or more and 3.38 Å or less, and most preferably 3.37
It has a peak of Å or more and 3.38 Å or less. Also, the size of the crystallite in the C-axis direction corresponding to this peak (Lc)
Is preferably 100 Å or more, more preferably 150 Å
Above, more preferably 200 Å or more, particularly preferably 221 Å or more and 1000 Å or less, most preferably 230
It is Å or more and 800 Å or less. This peak corresponds to the carbonaceous material (A) corresponding to the nucleus of the above-mentioned multiphase structure. further,
The multiphase carbonaceous material (M) of the present invention preferably has at least two peaks in X-ray wide-angle diffraction, corresponding to the above-described multiphase composite structure. That is, as a peak of X-ray wide-angle diffraction corresponding to the carbonaceous material (B) in the surface layer, d
₀₀₂ is 3.40Å or more, more preferably 3.43 to 3.75
Å, more preferably 3.45 to 3.70 Å, particularly preferably 3.46 to 3.67 Å, most preferably 3.47 to
It has a peak that is 3.60Å. Lc corresponding to this peak is preferably less than 100Å, more preferably 70Å or less, further preferably 7 to 50Å, particularly preferably 12 to 40Å, most preferably 15 to 35Å. In the separation of peaks in the X-ray wide-angle diffraction pattern, the profile of each peak was approximated by an asymmetric Pearson VII function, and the least squares method was separated by applying the Gauss-Jordan method.

[0015] In this way, the peak intensity ratio of the two peaks separated _{I (3.43~) / I (3.35~3} .43) is 0.001
It is preferably not less than 0.03, more preferably not less than 0.005, more preferably not less than 0.007 and not more than 0.45, and particularly preferably 0.010 to 0.40. , 0.012 or more and less than 0.03 is most preferable. Here, I _(3.43-) has d ₀₀₂ of 3.
It is the peak intensity of the peak of 43 Å or more, and I
_{(3.35 to 3.43)} is the peak intensity of the peak where d ₀₀₂ is 3.35 Å or more and less than 3.43 Å. Further, when the carbonaceous material (A) serving as a core further comprises two or more phases, it is 2 in the region where d ₀₀₂ is 3.35 Å or more and less than 3.43 Å in X-ray wide angle diffraction.
It has one or more peaks. Further, when the surface carbonaceous material (B) further comprises two or more phases, it has two or more peaks in the region where d ₀₀₂ is 3.43 Å or more in X-ray wide angle diffraction. In this case, I _{(3.43 ~)} is the sum of the peak intensities of the peaks with d ₀₀₂ of 3.43 Å or more, and I _{(3.35 ~ 3.43)} is d
Assuming that ₀₀₂ is the sum of the peak intensities of the peaks of 3.35 Å or more and less than 3.43 Å, the intensity ratio of both I _{(3.43 ~)} / I
_{(3.35 to 3.43)} is preferably in the range of the above values.

Further, I ( _{3.43 ~} , integrated intensity) is defined as the sum of integrated intensity of peaks with d ₀₀₂ of 3.43 Å or more, and I (
_{3.35 to 3.43} , integrated intensity) d ₀₀₂ is 3.35 to 3.43Å
Assuming the total integrated intensity of the peaks of
_3.43- , integrated intensity) / I ( _3.35-3.43 , integrated intensity) is preferably _0.001-1.60 , and 0.002
It is more preferably to 1.50, and 0.005-1.
It is more preferably 40, particularly preferably 0.01 to 1.30, and most preferably 0.10 to 1.20.

(Specific Surface Area) The multiphase carbonaceous material (M) used in the present invention has a specific surface area of 20 m ² / g or less, more preferably 15 m ² / g or less, as measured by the BET method. Preferably 0.1 to 12 m ² / g, particularly preferably 0.2 to 10 m ² / g, most preferably 0.3 to 8 mm.
² / g.

(Differential Heat) Further, the multiphase carbonaceous material (M) used in the present invention also exhibits an exothermic behavior in a wide temperature range in the differential thermal analysis depending on the above-mentioned multiphase structure. Preferably, the temperature range is 100 ° C. or higher, more preferably 150 ° C. or higher, further preferably 200 ° C.
In the above temperature range, particularly preferably 250 to 500 ° C
Shows the exothermic behavior most preferably in the temperature range of 280 to 400 ° C. The end temperature of the exothermic peak is preferably 800 ° C. or higher, more preferably 810 ° C. or higher, further preferably 820 to 980 ° C., particularly preferably 830 to 970 ° C., and most preferably 840 to 950.
℃. The starting temperature of the exothermic peak is preferably 70
0 ° C or lower, more preferably 680 ° C or lower, further preferably 550 to 680 ° C, particularly preferably 570 to 67.
0 ° C, most preferably 580 to 650 ° C. Also,
The exothermic peak temperature is preferably 650 to 840 ° C, preferably 660 to 835 ° C, and 670 to 670 ° C.
830 ° C. is more preferable, and 680 to 820
C. is particularly preferable, and 690 to 810.degree. C. is most preferable.

[Shape of Multiphase Carbonaceous Material (M)] A schematic representation of the multiphase carbonaceous material (M) that is the electrode material of the present invention is shown in FIG. In this figure, 1 is a carbonaceous material (A) serving as a nucleus, and 2 is a carbonaceous material (B) serving as a surface layer.
Is. That is, the multiphase carbonaceous material (M) is formed by adopting a multiphase composite structure in which the carbonaceous material (A) serving as the core is covered with the carbonaceous material (B). The multiphase carbonaceous material (M) according to the present invention may have any shape such as a particle shape or a fiber shape, but is preferably a particle shape or a fiber shape, and particularly preferably a particle shape. In the case of particles, the volume average particle size is preferably 3 to 100 μm, more preferably 6 to 70 μm, and further preferably 10 to 60.
μm, particularly preferably 15 to 50 μm, most preferably 20 to 40 μm. In the case of a fibrous shape, the diameter is preferably 50 μm or less, more preferably 30 μm or less, further preferably 0.1 to 25 μm, and particularly preferably 0.5.
˜20 μm, most preferably 1 to 15 μm. The length is preferably 10 mm or less, more preferably 5
mm or less, more preferably 2 mm or less, particularly preferably 1 mm or less, and most preferably 0.5 mm or less.

[Production of Multiphase Carbonaceous Material (M)] The multiphase carbonaceous material (M) which is the electrode material of the present invention can be produced by the following method. That is, after coating an organic compound on the surface of the carbonaceous material (A) serving as a core, the carbonized material is carbonized to form a carbonaceous material (B), and the specific surface area of the carbonaceous material (A) of the core is 1/2 or less. Particles or fibers of a multiphase carbonaceous material (M) having a specific surface area. Hereinafter, the synthesis of the carbonaceous material (A) as the core and the subsequent formation of the carbonaceous material (B) as the surface layer will be described.

(Synthesis of Core Carbonaceous Material (A)) The core carbonaceous material (A) can be synthesized, for example, by the following method. That is, first, the organic substance is heated to 300 to 3000 ° C., preferably 50, in an inert gas flow or in a vacuum.
Decomposes by heating at a temperature of 0-3000 ° C,
Carbonization and graphitization are carried out to synthesize a carbonaceous material (A) as a core. As a starting material for obtaining the carbonaceous material (A) which is the core of the present invention, naphthalene, phenanthrene, anthracene, triphenylene, pyrene, chrysene, naphthacene, picene, perylene, pentaphene, pentacene, a 3-membered ring or more A condensed polycyclic hydrocarbon compound obtained by condensing two or more monocyclic hydrocarbon compounds with each other; or a derivative of the above compound, such as a carboxylic acid, a carboxylic acid anhydride or a carboxylic acid imide; Various pitches to be used; whether at least two heterocyclic monocyclic compounds having three or more members, such as indole, isoindole, quinoline, isoquinoline, quinoxaline, phthalazine, carbazole, acridine, phenazine, phenanthridine, are bound to each other , Or one or more three-membered or more monocyclic hydrocarbon compounds A fused heterocyclic compound obtained by combining these; carboxylic acids, carboxylic acid anhydrides, derivatives such as carboxylic acid imides of the above compounds; aromatic monocyclic hydrocarbons such as benzene, toluene, xylene, and carboxylic acids thereof. Derivatives such as carboxylic acid anhydrides and carboxylic acid imides, for example, 1,2,4,5-tetracarboxylic acid, dianhydrides and derivatives thereof such as diimides.

The pitch will be described in more detail below.
Ethylene heavy-end pitch generated during naphtha decomposition, crude oil pitch generated during crude oil decomposition, coal pitch generated during thermal decomposition of coal, asphalt decomposition pitch generated by asphalt decomposition, polyvinyl chloride, etc. Pitch etc. which generate | occur | produce by thermal decomposition can be mentioned as an example. Further, these various pitches are further heated under an inert gas flow or the like to be used as a mesophase pitch having a quinoline insoluble content of preferably 80% or more, more preferably 90% or more, further preferably 95% or more. You can Furthermore, aliphatic saturated or unsaturated hydrocarbons such as propane and propylene are also used. Furthermore, acrylic resins such as poly (α-halogenated acrylonitrile), polyvinyl chloride, polyvinylidene chloride,
Examples thereof include organic polymer compounds such as vinyl halide resins such as chlorinated polyvinyl chloride and conjugated resins such as polyacetylene and polyphenylene vinyl. Alternatively, a carbonaceous material such as carbon black or coke as a starting material may be further heated to appropriately promote carbonization and be used as the nucleus of the carbonaceous material (A) used in the present invention. As the carbonaceous material (A) serving as the nucleus, natural graphite, artificial graphite, or vapor-grown graphite whiskers can be used.

(Formation of carbonaceous material (B) serving as a surface layer) Next, with the carbonaceous material (A) obtained as described above as a nucleus, an organic compound is heated and decomposed under an inert gas flow,
Carbonize and form a new carbonaceous material (B) on the surface of the nucleus
To form the surface layer of. Examples of the method for forming the carbonaceous material (B) as a surface layer by coating the surface of the carbonaceous material (A) as a core with an organic compound and then heating and decomposing the same include the following methods, which are arbitrarily selected. can do. (1) A relatively low molecular weight organic compound is coated and then pyrolyzed to deposit a carbonaceous material (B) on the surface layer. Specific examples of the organic compound include aromatic monocyclic hydrocarbons such as benzene and toluene, naphthalene, phenanthrene, anthracene, triphenylene, pyrene, chrysene, naphthacene, picene, perylene, pentaphene, and pentacene. Carboxylic acids of hydrocarbons, carboxylic acid anhydrides, derivatives such as carboxylic acid imides, carboxylic acids of 3- or more-membered heteropolycyclic compounds such as indole, isoindole, quinoline, carboxylic acid anhydrides, carboxylic acid imides And derivatives such as The above compound is dissolved in an organic solvent, the carbonaceous material (A) is mixed and heated, the organic solvent is evaporated, and the carbonaceous material (A) is evaporated.
After the organic compound is coated on the surface of the above, it is heated and carbonized to form the carbonaceous material (B) in the surface layer. (2) The surface of the carbonaceous material (A) serving as a core is coated with an organic polymer compound, and then thermally decomposed in a solid phase to form the carbonaceous material (B).
To form. Organic polymers such as cellulose; phenol resins; acrylic resins such as polyacrylonitrile and poly (α-halogenated acrylonitrile); polyamideimide resins; polyamide resins; (3) A condensed polycyclic hydrocarbon, a heteropolycyclic compound, or the like is coated, and then heated to form a surface carbonaceous material (B) on the surface of the carbonaceous material (A) serving as a nucleus in a liquid phase. The above-mentioned pitch is preferably used as the condensed polycyclic hydrocarbon. In particular, in the method of heating the condensed polycyclic hydrocarbon on the surface of the carbonaceous material (A) serving as a nucleus, carbonization proceeds through a liquid crystal state called mesophase to form a carbonaceous material (B) in the surface layer. Is preferred. The thermal decomposition temperature for forming the surface layer is usually lower than the temperature for synthesizing the carbonaceous material (A) serving as a core, and is preferably 300 to 2,000 ° C.

On the surface of the carbonaceous material (A) which becomes the core,
When coating the organic compound, it is preferable to coat and carbonize until the specific surface area of the carbonaceous material (A) of the core is 1/2 or less of the specific surface area U (A). More preferably 1/3 or less, still more preferably 1/4 or less, particularly preferably 1
/ 5 or less, most preferably 1/6 or less. In the synthesis of the carbonaceous material (A) as the nucleus, the inner nucleus is synthesized, and then the outer nucleus is synthesized thereon to synthesize the carbonaceous material (A) as the multiphase nucleus in multiple stages. Similarly, in the synthesis of the carbonaceous material (B) that becomes the surface layer, the inner surface layer can be synthesized, and the outer surface layer can be synthesized thereon to synthesize the carbonaceous material (B) that becomes the multiphase surface layer in multiple stages. it can.

The following embodiment is suitable as a typical method for producing the multiphase carbonaceous material (M). That is,
Particles having a true density of 2.15 g / cm ³ or more, a peak of the interplanar spacing d ₀₀₂ of the (002) plane of less than 3.40 Å by the X-ray wide angle diffraction method, and a volume average particle diameter of 35 μm or less or an average diameter Having a carbonaceous material (A) consisting of fibers having a particle size of 20 μm or less as a core, the surface of the carbonaceous material is coated with an organic compound and then carbonized, and a carbonaceous material having a d ₀₀₂ by an X-ray wide angle diffraction method of 3.40Å or more (B ) To form particles or fibers of the multiphase carbonaceous material (M) having a specific surface area of 1/2 or less of the specific surface area of the carbonaceous material (A) as a core, to produce the electrode material of the present invention. You can

In the multiphase carbonaceous material (M) having a multiphase composite structure thus obtained, the ratio of the core portion to the surface portion is preferably 35 to 92% by weight, Preferably 45-85% by weight, more preferably 50
-80% by weight, particularly preferably 55-75% by weight, most preferably 60-70% by weight. The surface layer portion is preferably 8 to 65% by weight, more preferably 15% by weight.
To 55% by weight, more preferably 20 to 50% by weight, particularly preferably 25 to 45% by weight, most preferably 30.
-40% by weight. The thickness of the surface layer enclosing the core is preferably 100Å to 5 μm, more preferably 200Å to 4
μm, more preferably 300 Å to 3 μm, particularly preferably 500 Å to 2 μm, most preferably 700 Å
˜1.5 μm.

(Additive to Multiphase Carbonaceous Material (M)) Further, the multiphase carbonaceous material (M) of the present invention is a metal capable of forming an alloy with an alkali metal and / or an alloy of an alkali metal. Can be used as a mixture. As the metal capable of forming an alloy with an alkali metal, preferably a metal capable of forming an alloy with a lithium metal, for example, aluminum (Al), lead (Pb), zinc (Zn), tin (Sn) , Bismuth (Bi), indium (In), magnesium (Mg), gallium (Ga), cadmium (Cd), silver (Ag), silicon (Si), boron (B), antimony (Sb), and the like, Al, Pb, In, Bi and Cd are preferable, Al, Pb and In are more preferable, and Al and Pb are particularly preferable.
And most preferably Al. As an alloy with an alkali metal, preferably an alloy with lithium metal, when the composition (molar composition) of the alloy is represented by Li x M (x is a molar ratio to the metal M), the above-mentioned metal is used as M. .. The alloy may further contain other elements other than the above-mentioned metals in a range of 50 mol% or less.

In Li x M, x preferably satisfies 0 <x ≦ 9, more preferably 0.1 ≦ x ≦ 5, still more preferably 0.5 ≦ x ≦ 3, and particularly preferably. 0.7 ≦ x ≦ 2. Active material alloy (Li x
As M), one kind or two or more kinds of alloys can be used. As the alloyable metal of the active material, one kind or two or more kinds of the above metal M can be used. The ratio of the alkali metal-alloyable metal or alkali metal alloy in the mixture of the multiphase carbonaceous material (M) of the present invention and the alkali metal alloyable metal or alkali metal alloy is preferably 3 to 60. % By weight, more preferably 5 to 5
0% by weight, more preferably 7 to 45% by weight, particularly preferably 10 to 40% by weight, most preferably 12 to 35%.
% By weight. As a mixed form of the multiphase carbonaceous material (M) of the present invention and a metal capable of alloying with an alkali metal or an alloy of an alkali metal, the following mixed forms are most preferable. That is, it is preferable that the carbonaceous material (A) and a metal that can be alloyed with an alkali metal or an alloy of an alkali metal are covered by the carbonaceous material (B).

(Physical Properties of Core Carbonaceous Material (A)) Since the multiphase carbonaceous material (M) of the present invention has the above-described multiphase composite structure, the core carbonaceous material (A) and Each of the surface carbonaceous materials (B) also has preferable physical properties. The carbonaceous material (A) serving as a core has a true density (ρ) of 2.15 g / cm ³ or more, more preferably 2.1.
6 to 2.26 g / cm ³ , more preferably 2.18 to 2.
26 g / cm ³ , particularly preferably 2.19 to 2.25 g
/ Cm ³ , most preferably 2.20 to 2.24 g / cm ³ .

The carbonaceous material (A) serving as a core has a peak in which the interplanar spacing d _{00 2} of the (002) plane is less than 3.40Å, preferably 3.35 to 3.40Å, more preferably 3 in X-ray wide angle diffraction. .35-3.39Å, more preferably 3.36-3.
It has a peak of 38Å, most preferably 3.37 to 3.38Å. The crystallite size (Lc) in the C-axis direction is preferably 100 Å or more, more preferably 150 Å or more,
More preferably 200 Å or more, particularly preferably 22
1-1000Å, most preferably 230-800Å. The carbonaceous material (A) serving as a core can have any shape such as a particle shape or a fiber shape, but is preferably a particle shape or a fiber shape, and particularly preferably a particle shape. The particles of the carbonaceous material (A) serving as the core preferably have a volume average particle diameter of 35 μm.
Or less, preferably 30 μm or less, more preferably 25 μm
m or less, more preferably 20 μm or less, particularly preferably 0.1 to 15 μm, most preferably 0.2 to 10 μm.
Is. The fibers of the carbonaceous substance (A) serving as the core have an average diameter of 20 μm or less, preferably 18 μm or less, more preferably 15 μm or less, still more preferably 14 μm or less,
It is particularly preferably 0.1 to 12 μm, most preferably 0.2 to 10 μm.

Specific surface area U (A) of carbonaceous material (A) serving as a core
Is preferably 0.1 m ² / g or more, more preferably 0.1 m ² / g or more.
5 m ² / g or more, more preferably 1 to 1,000 m ² /
g, particularly preferably ² to 500 m ² / g, most preferably 5 to 400 m ² / g. Letting U (A) be the specific surface area of the carbonaceous material (A) and U (M) of the multiphase carbonaceous material (M), the following relationship exists between them. preferable. U (A) ≧ 2 U (M) Preferably U (A) ≧ 3 U (M), more preferably U (A) ≧
3U (M), more preferably U (A) ≧ 5U (M), particularly preferably U (A) ≧ 8U (M), most preferably 500U (M).
≧ U (A) ≧ 10U (M). In order to make the relationship between the surface areas of the two as described above, the carbonaceous material (B) is formed by carbonizing the organic compound on the surface of the carbonaceous material (A) serving as a core,
There is also a method of directly making particles or fibers of a multiphase carbonaceous material (M) having a specific surface area U (M) of 1/2 or less of the specific surface area U (A) of the carbonaceous material (A), or the carbonaceous material (A) After carbonizing an organic compound on the surface of the carbonaceous material (B) to form a carbonaceous material (B), a specific surface area U (M) of 1/2 or less of the specific surface area U (A) of the carbonaceous material (A) which becomes a nucleus through a pulverizing step. There is also a method of forming particles of a multiphase carbonaceous material (M) having a).

[Manufacture of Electrode] The multiphase carbonaceous material (M), which is the electrode material according to the present invention, is usually mixed with a polymer binder to form an electrode material, and then formed into the shape of an electrode. Examples of the polymer binder include the following. Resinous polymers such as polyethylene, polypropylene, polyethylene terephthalate, aromatic polyamide, cellulose, polyvinylidene fluoride. Rubber-like polymers such as styrene / butadiene rubber, isoprene rubber, butadiene rubber, ethylene / propylene rubber. Styrene / butadiene / styrene block copolymer,
Thermoplastic elastomeric polymers such as hydrogenated products, styrene-isoprene-styrene block copolymers, hydrogenated products. Soft resinous polymers such as syndiotactic 1,2-polybutadiene, ethylene / vinyl acetate copolymers, propylene / α-olefin (C2 or C4-12) copolymers. A polymer composition having an ionic conductivity of alkali metal ions, particularly Li ions. Examples of the above-mentioned ion conductive polymer composition include polymer compounds such as polyethylene oxide, polypropylene oxide, polyepichlorohydrin, polyphosphazene, polyvinylidene fluoride, and boriaacrylonitrile, and an alkali containing lithium salt or lithium as a main component. A system in which a metal salt is compounded, or a system in which an organic compound having a high dielectric constant such as propylene carbonate, ethylene carbonate, or γ-butyrolactone is further mixed can be used. The polyphosphazene preferably has a polyether chain, particularly a polyoxyethylene chain, in the side chain. The ion conductivity of such an ion-conductive polymer composition at room temperature is preferably 10 ⁻⁸ S · cm ⁻¹ or more, more preferably 10 ⁻⁶ S · cm ⁻¹ or more, further preferably 10 ⁻⁴ S. -Cm ^-1 or more, particularly preferably 10 ^-3
It is S · cm ⁻¹ or more. As the mixed form of the multiphase carbonaceous material (M) of the present invention and the above-mentioned polymer binder, various forms can be adopted. That is, a form in which both particles are simply mixed, a form in which a fibrous binder is entangled with the particles of the multiphase carbonaceous material (M), or the above rubber-like polymer, thermoplastic elastomer, soft resin, Examples include a form in which a layer of a binder such as an ion conductive polymer composition is attached to the surface of particles of the multiphase carbonaceous material (M).

When a fibrous binder is used, the diameter of the fiber of the binder is preferably 10 μm or less, more preferably 5 μm or less, fibrils (ultrafine fibers), and fibrid (tactile-like ultrafine fibers). Powder with fibrils)
Is particularly preferable. The mixing ratio of the multiphase carbonaceous material (M) and the binder is preferably 0.1 to 30 parts by weight with respect to 100 parts by weight of the multiphase carbonaceous material (M),
It is more preferably 0.5 to 20 parts by weight, still more preferably 1 to 10 parts by weight. The multi-phase carbonaceous material (M) used in the present invention is a mixture with the above-mentioned binder; or a metal capable of forming an alloy with the active material or an alloy of the active material and the metal as described above. It is possible to obtain an electrode molded body by forming an electrode material composed of a mixture of the above, and molding the electrode material as it is into a shape of an electrode by a method such as roll molding or compression molding. Alternatively, these components may be dispersed in a solvent and applied to a metal collector or the like. The shape of the electrode molded body can be arbitrarily set to a sheet shape, a pellet shape, or the like.

[Support of Active Material] The electrode molded body thus obtained may be supported with an alkali metal, preferably lithium metal, which is an active material, prior to or during assembly of a battery. it can. As a method for supporting the active material on the carrier, there are a chemical method, an electrochemical method, a physical method and the like. For example, a method of immersing an electrode molded body in an electrolytic solution containing a predetermined concentration of alkali metal cations, preferably Li ions, and using lithium as a counter electrode to make the electrode molded body an anode and impregnate the electrode, an electrode molded body In the process of obtaining, a method of mixing an alkali metal powder, preferably a lithium powder, can be applied. Alternatively, a method of electrically contacting the lithium metal and the electrode molded body is also used. In this case, it is preferable to bring the lithium metal and the carbonaceous material in the electrode molded body into contact with each other through the lithium ion conductive polymer plastic material. The amount of lithium thus preliminarily supported on the electrode molded body is preferably 0.030 to 0.250 per 1 part by weight of the carrier.
Parts by weight, more preferably 0.060 to 0.200 parts by weight,
It is more preferably 0.070 to 0.150 parts by weight, particularly preferably 0.075 to 0.120 parts by weight, and most preferably 0.080 to 0.100 parts by weight. An electrode using such a multiphase carbonaceous material (M) of the present invention is usually used as a negative electrode of a secondary battery, and is opposed to a positive electrode via a separator.

[Positive Electrode] The material of the positive electrode body is not particularly limited, but for example, it is preferably composed of a metal chalcogen compound that releases or acquires an alkali metal cation such as Li ion along with a charge / discharge reaction. Such metal chalcogen compounds include vanadium oxide, vanadium sulfide, molybdenum oxide, molybdenum sulfide, manganese oxide, chromium oxide, titanium oxide, titanium sulfide, and these. Complex oxides, complex sulfides, and the like. Preferably Cr ₃ O ₈ , V ₂
O ₅ , V ₆ O ₁₃ , VO ₂ , Cr ₂ O ₅ , MnO ₂ , TiO ₂ ,
MoV ₂ O ₈ ; TiS ₂ , V ₂ S ₅ , MoS ₂ , MoS ₃ , V
S ₂ , Cr _0.25 V _0.75 S ₂ , Cr _0.5 V _0.5 S ₂ , and the like. Further, oxides such as LiCoO ₂ and WO ₃ ; CuS,
Fe _0.25 V _0.75 S ₂ , sulfides such as Na _0.1 CrS ₂ ; N
Phosphorus and sulfur compounds such as iPS ₃ and FePS ₃ ; VSe
It is also possible to use a selenium compound such as ₂ , NbSe ₃ . Further, a conductive polymer such as polyaniline or polypyrrole can be used.

The specific surface area is 10 m ² / g or more, preferably 100 m ² / g or more, more preferably 500 m ²
/ G or more, particularly preferably 1000 m ² / g or more, most preferably 2000 m ² / g or more carbonaceous material can be used for the positive electrode. In a battery thus configured, for example, a battery in which a metal chalcogen compound is used for the positive electrode and the multiphase carbonaceous material (M) of the present invention is used for the negative electrode, an active material ion (especially lithium ion) is charged at the time of charging in the negative electrode. Is preferable) and the active material ions are released during discharge, so that the electrode reaction of charge and discharge proceeds. In the positive electrode, active material ions are released from the positive electrode body at the time of charging and are doped at the time of discharging, and the electrode reaction of charge and discharge proceeds. Further, in a battery in which the above-mentioned conductive polymer or a carbonaceous material having a large specific surface area is used for the positive electrode and the multiphase carbonaceous material (M) of the present invention is used for the negative electrode, the negative electrode is charged in the electrolytic solution at the time of charging. Doped with cations, the cations in the negative electrode body are released during discharge,
Charge and discharge electrode reactions proceed. On the other hand, in the positive electrode,
At the time of charging, the anions in the electrolytic solution are doped, and at the time of discharging, the anions in the positive electrode body are released, and the electrode reaction of charging / discharging proceeds. The secondary battery using the multiphase carbonaceous material (M) of the present invention for the negative electrode has a good balance between battery capacity and long-term charge / discharge cycle characteristics, and exhibits excellent self-discharge characteristics and safety characteristics.

[Electrolytic Solution] As the electrolytic solution in the secondary battery using the negative electrode of the electrode material of the present invention, LiC is used.
lO ₄ , LiPF ₆ , LiAsF ₆ , LiBF ₄ , LiSO
Alkali metal salts such as ₃ CF ₃ and LiN (SO ₂ CF ₃ ) ₂ and electrolyte salts such as tetraalkylammonium salts are added to propylene carbonate, ethylene carbonate, butylene carbonate, diethyl carbonate, 1,2-dimethoxyethane, tetrahydrofuran, 1 It is possible to use those dissolved in a solvent such as 3,3-dioxolane. A solid electrolyte having lithium ion conductivity can also be used as the electrolyte. The separator that holds the electrolytic solution is generally a material with excellent liquid retention, such as polyethylene,
A non-woven fabric made of polyolefin such as polypropylene can be used.

[Assembly of Secondary Battery] In the secondary battery, for example, a metal collecting net is placed on a positive electrode can, and a positive electrode material, a separator containing an electrolytic solution, a negative electrode material, and a metal collecting metal. Netting, and then stacking on it in the order of negative electrode can,
It is assembled by sealing the ends with gaskets.

[Measurement Method] In the present invention, (a)
The vacuum degree, (b) Raman spectrum, (c) X-ray wide angle diffraction, and (d) specific surface area were measured by the following methods. (A) Degree of vacuum: Measured by using a multi-pycnometer (manufactured by Yuasa Ionics Co., Ltd.) and a gas replacement method with helium gas. (B) Raman spectrum: Measured using Argon ion laser light as a light source and JASCO NR1000 as a spectroscope. (C) X-ray wide-angle diffraction: Interplanar spacing of ( ₀₀₂ ) plane (d ₀₀₂ ) If the carbonaceous material is a powder, it is powdered in an agate mortar if it is in the form of fine particles. X
A high-purity silicon powder for a line standard is mixed as an internal standard substance, the sample cell is filled, and a CuKα ray monochromatized by a graphite monochromator is used as a radiation source to measure a wide-angle X-ray diffraction curve by a reflection type diffractometer method. For the correction of the curve, so-called Lorentz, polarization factor, absorption factor, atomic scattering factor, etc. are not corrected, and the following simple method is used. That is, the baseline of the curve corresponding to the (002) diffraction is drawn, and the substantial intensity from the baseline is plotted again to obtain the correction curve of the (002) plane. Obtain the midpoint of the line segment where the line parallel to the angle axis drawn to the height of two-thirds of the peak height of this curve intersects the diffraction curve, correct the angle of the midpoint with the internal standard, and turn this. The bending angle is doubled, and d ₀₀₂ is obtained from the wavelength λ of the CuKα ray by the following Bragg equation.

[0040]

[Equation 4]

(2) C-axis crystallite size: Lc In the corrected diffraction curve obtained in the previous section, the so-called half-value width β at half the peak height was used to determine the c-axis crystallite size. Is calculated from the following formula.

[0042]

[Equation 5]

The form factor K was 0.90. λ, θ
Has the same meaning as in the previous section. (D) Specific Surface Area The present invention will be further described below with reference to Examples.

[0044]

Example (Example 1) (1) Preparation of Negative Electrode Pitch 10 g was 500 at a temperature rising rate of 2 ° C./min in a nitrogen stream.
The temperature was raised to ℃ and kept at 500 ℃ for 30 minutes. Further 10 ℃
The temperature is raised to 2800 ° C at a heating rate of 1 / min, and 3 at 2800 ° C.
Hold for 0 minutes. The carbonaceous material (A) thus formed had a d ₀₀₂ of 3.36Å in X-ray wide angle diffraction. The carbonaceous material (A) was mechanically pulverized into particles having an average particle size of 6 μm. The specific surface area of this particle is 15 m ² /
It was g. The particles of the carbonaceous material (A) are heated while being stirred in a solution of pitch (a mixture of condensed polycyclic hydrocarbon compounds) dissolved in a toluene solvent, so that the pitch on the surface of the particles of the carbonaceous material (A). Coated. A carbonaceous material obtained by coating a pitch on the surface of the particles of the carbonaceous material (A) serving as the core is heated at 20 ° C. under a nitrogen gas flow.
The temperature is raised to 1200 ° C at a heating rate of 1 minute, and the temperature is raised to 1200 ° C for 30 minutes.
Hold for minutes. In this way, the surface carbonaceous material (B) was formed on the surface of the core carbonaceous material (A) particles to obtain a multiphase carbonaceous material (M). This was lightly pulverized to obtain a multiphase carbonaceous material (M) having an average particle size of 20 μm. The ratio of the carbonaceous material (B) in the surface layer was 45 parts by weight with respect to 100 parts by weight of the carbonaceous material (A) serving as the core. The G value of the multiphase carbonaceous material (M) having this multiphase composite structure was 0.80 in Raman spectrum analysis using an argon ion laser beam (5145Å). Also H / C
The atomic ratio was 0.01. The BET specific surface area is 1.3
It was m ² / g. The true density (ρ) was 2.14 g / cm ³ . Further, in the X-ray wide angle diffraction, d ₀₀₂ was 3.36.
It had two peaks, Å and 3.50 Å. L _C was 460Å and 30Å respectively. This multiphase carbonaceous material (M) 9
Mix 6 parts by weight of polyethylene with 4 parts by weight to obtain a diameter of 16
It was compression molded into a mm-shaped pellet electrode. This is 130 ℃
Heated and dried under vacuum.

(2) Electrode evaluation A solution prepared by dissolving LiClO ₄ in a glass cell at a concentration of 1 mol / l in a mixed solvent of propylene carbonate (25 vol%), ethylene carbonate (25 vol%) and diethyl carbonate (50 vol%) was prepared. Then, the electrode molded body was suspended from the upper part of the cell to form one electrode. An electrode in which lithium metal was pressure-bonded to a Ni wire netting facing this was used as one electrode. The operation of charging between both electrodes with a constant current of 0.5 mA / cm ² to 0 V and discharging to 1.5 V was repeated. Table 1 shows the characteristics of the 3rd and 15th cycles.
It was shown to.

Comparative Example 1 (1) Preparation of Negative Electrode A carbonaceous material (A) was synthesized in the same manner as in Example 1. A mixture of 90 parts by weight of this carbonaceous material (A) and 10 parts by weight of pitch was used under a nitrogen gas flow at a temperature rising rate of 20 ° C./min for 120%.
The temperature was raised to 0 ° C., and the temperature was kept at 1200 ° C. for 30 minutes to form a carbonaceous material (B) on the surface layer. The multiphase carbonaceous material (M) thus obtained had a G value of 0.26 as defined above in a Raman spectrum analysis using an argon ion laser beam (5145Å). True density (ρ) is 2.25g /
It was cm ³ . Using this multi-phase carbonaceous material (M), a negative electrode was prepared in the same manner as in Example 1. (2) Electrode Evaluation A battery cell was constructed in the same manner as in Example 1, the electrode characteristics thereof were evaluated, and summarized in Table 1.

[0047]

[Table 1]

[0048]

As described above, according to the present invention, the negative electrode containing the multiphase carbonaceous material (M) having specific physical characteristics as a main component has a large charge / discharge capacity and long-term charge / discharge cycle characteristics. It is possible to make a secondary battery that is excellent, has little self-discharge, and is highly safe, and its industrial value is extremely large.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing a multiphase carbonaceous material (M) of the present invention.

[Explanation of symbols]

 1 Carbonaceous matter (A) 2 Carbonaceous matter (B)

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[Procedure amendment]

[Submission date] May 28, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0012

[Correction method] Change

[Correction content]

2.03 ≦ ρ ≦ 2.26 (2) G ≧ 0.30 (3) G ≧ −1.50ρ + 3.50 (4) Preferably, the following (2 ′) , (3 ′) and (4 ′) are satisfied. 2.05 ≦ ρ ≦ 2.24 (2 ′) G ≧ 0.35 (3 ′) G ≧ −1.50ρ + 3.55 (4 ′) More preferably, the following (2 "), (3") and (4 ") are satisfied. 2.08≤ρ≤2.22 (2") G≥0.40 (3 ") G≥-1 .50ρ + 3.60 (4 ″) More preferably, the following (2 ′ ″) and (3 ′ ″)
And the condition of the expression (4 ″ ′) is satisfied. 2.10 ≦ ρ ≦ 2.21 (2 ′ ″) G ≧ 0.45 (3 ′ ″) G ≧ −1.50ρ + 3.65 (4 ″ ′) Especially Preferably, the following (2 ''''),
The conditions of the expressions (3 ″ ″) and (4 ″ ″) are satisfied. 2.12 ≦ ρ ≦ 2.20 (2 ″ ″) 1.2 ≧ G ≧ 0.50 ... (3 ″ ″) G ≧ −1.50ρ + 3.70 ( 4 ″ ″) Most preferably, the following (2 ′ ″ ″),
The conditions of (3 ''''') and (4''''') are satisfied. 2.13 ≦ ρ ≦ 2.19 (2 ′ ″ ″) 1.1 ≧ G ≧ 0.55 (3 ″ ″ ′) G ≧ −1.50ρ + 3.75 ...・ (4 ''''')

[Submission date] May 28, 1992

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0015

[Correction method] Change

[Correction content]

The peak intensity ratio I _{(3.43 to)} / I _{(3.35 to 3.43)} of the two peaks thus separated is 0.0
It is preferably 01 or more, more preferably 0.005 or more, more preferably 0.007 or more and 0.45 or less, particularly preferably 0.010 to 0.40,
Most preferably, it is 0.012 or more and less than 0.03. Here _{I (3.43~)} is the peak intensity of the peak d ₀₀₂ is more than _3.43Å, I _(3.35~3.43) is d ₀₀₂ is more than 3.35 Å 3.43
It is the peak intensity of peaks less than Å. When the core carbonaceous material (A) further comprises two or more phases, 2 in the region where d ₀₀₂ is 3.35 Å or more and less than 3.43 Å in X-ray wide angle diffraction.
It has one or more peaks. When the surface carbonaceous material (B) further comprises two or more phases, it has two or more peaks in the region where d ₀₀₂ is 3.43 Å or more in X-ray wide angle diffraction. In this case, I _{(3.43 ~)} d ₀₀₂ is 3.43Å
The sum of the peak intensities of the above peaks is I _{(3.35 to 3.43)}
Let d ₀₀₂ be the sum of the peak intensities of the peaks in which d ₀₀₂ is 3.35 Å or more and less than 3.43 Å, the intensity ratio of the two I _{(3.43 ~)} / I
_{(3.35 to 3.43)} is preferably in the range of the above values.

Claims (2)

[Claims] 1. An electrode material mainly comprising particles or fibers of a multiphase carbonaceous material (M) having the following characteristics (a), (b), (c) and (d): (b) H / C atomic ratio is 0.08 or less; (b) In the Raman spectrum analysis using an argon ion laser beam having a true density of ρ (g / cm ³ ) and a wavelength of 5145Å, the value represented by the following formula (1) Is the G value, the ρ and the G value must satisfy the conditions of the following expressions (2) to (4); 2.03 ≦ ρ ≦ 2.26 (2) G ≧ 0.30 (3) G ≧ −1.50ρ + 3.50 (4) (C) X-ray wide-angle diffraction (002 ) Surface spacing d
₀₀₂ has at least one peak less than 3.40Å; (d) The specific surface area is 20 m ² / g or less. 2. The true density is 2.15 g / cm ³ or more, and the interplanar spacing d ₀₀₂ of the (002) plane by the X-ray wide angle diffraction method is 3.40Å.
A carbonaceous material (A) having a peak of less than, and having a volume average particle diameter of 35 μm or less or a fiber having an average diameter of 20 μm or less is used as a core, and the surface of the carbonaceous material (A) is coated with an organic compound. Multi-phase carbon which is post-carbonized to form a carbonaceous material (B) having d ₀₀₂ of 3.40 Å or more by X-ray wide-angle diffraction method and having a specific surface area of 1/2 or less of the specific surface area of the carbonaceous material (A) as a core. The method for producing an electrode material according to claim 1, wherein the particles or fibers of the substance (M) are used.