JP2006089349A - Method for producing carbon material, negative electrode material for secondary battery, and nonaqueous electrolyte secondary battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a carbon material capable of producing a negative electrode material for a nonaqueous electrolyte secondary battery excellent in charge/discharge characteristics, a negative electrode material for a secondary battery and a nonaqueous electrolyte secondary battery using the carbon material obtained by the method. <P>SOLUTION: This method for producing a carbon material by carbonizing treatment of a resin composition comprises the steps of (a) preparing a phosphorus-containing carbon material precursor by mixing a resin composition with a phosphorus-containing compound, (b) carbonizing the phosphorus-containing carbon material precursor and (c) washing the carbonized product with water to substantially remove phosphorus component existing at least in the surface site. Further, the negative electrode material for the secondary battery containing the carbon material, and the nonaqueous electrolyte secondary battery using the negative electrode material for a secondary battery are disclosed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing a carbon material, a negative electrode material for a secondary battery, and a nonaqueous electrolyte secondary battery.

Carbon materials are used in a wide range of applications such as negative electrodes for lithium ion secondary batteries, capacitor electrodes, electrodes for electrolysis, and activated carbon, and are areas where further development is expected in the future.
These carbon materials are conventionally made from coconut shell, coal coke, coal or petroleum pitch, furan resin, phenol resin, and the like (for example, see Patent Document 1). However, the conventional carbon materials obtained from these raw materials have a large variation in pore diameter formed on the surface, and each pore volume is large, so that they are particularly used as negative electrode materials for non-aqueous electrolyte secondary batteries. In some cases, the characteristics are not sufficient in terms of charge / discharge capacity and cycleability.

JP 05-043345 A

  The present invention relates to a method for producing a carbon material capable of producing a negative electrode material for a nonaqueous electrolyte secondary battery excellent in charge / discharge characteristics, and a negative electrode for a secondary battery using the carbon material obtained by the production method. The present invention provides a material and a nonaqueous electrolyte secondary battery.

Such an object is achieved by the following present inventions (1) to (6).
(1) A method for producing a carbon material obtained by carbonizing a resin composition,
(A) a step of mixing a resin composition and a phosphorus-containing compound to prepare a phosphorus-containing carbon material precursor;
(B) a step of carbonizing the phosphorus-containing carbon material precursor, and
(C) washing the treated product after the carbonization treatment with water to substantially remove a phosphorus component present at least on the surface of the treated product;
A method for producing a carbon material, comprising:
(2) The said resin composition is a manufacturing method of the carbon material as described in said (1) which has 1 or more types chosen from a novolak type phenol resin, a melamine resin, a furan resin, and an aniline resin.
(3) The method for producing a carbon material according to (1) or (2), wherein the phosphorus-containing compound is mixed with the resin composition in an amount of 0.1 to 15% by weight in terms of a phosphorus component. .
(4) The carbon material according to any one of (1) to (3), wherein a pore volume having a pore diameter exceeding 0.33 nm formed on a surface thereof is 0.1 to 50 ml / kg. Carbon material manufacturing method.
(5) A negative electrode material for a secondary battery, comprising a carbon material obtained by the production method according to any one of (1) to (4) above.
(6) A nonaqueous electrolyte secondary battery using the secondary battery negative electrode material described in (5) above.

In the present invention, a resin composition and a phosphorus-containing compound are mixed to prepare a phosphorus-containing carbon material precursor. After carbonizing the precursor, the processed product after carbonization is washed with water, and at least the surface of the processed product is washed. It is a method for producing a carbon material characterized by having a step of substantially removing a phosphorus component present at a site, and a carbon material having a suitable amount of pores formed on the surface can be produced.
And the negative electrode material for nonaqueous electrolyte secondary batteries excellent in the charge / discharge characteristic can be obtained by using the carbon material obtained by the manufacturing method of this invention.

Hereinafter, a method for producing a carbon material of the present invention (hereinafter sometimes simply referred to as “manufacturing method”), a negative electrode material for a secondary battery using the carbon material obtained by this production method, and a non-aqueous electrolyte The secondary battery will be described in detail.
The production method of the present invention is a method for producing a carbon material obtained by carbonizing a resin composition,
(A) a step of mixing a resin composition and a phosphorus-containing compound to prepare a phosphorus-containing carbon material precursor;
(B) a step of carbonizing the phosphorus-containing carbon material precursor, and
(C) washing the treated product after the carbonization treatment with water to substantially remove the phosphorus component present at least on the surface of the treated product;
It is characterized by having.
Moreover, the negative electrode material for secondary batteries of this invention contains the carbon material obtained by the manufacturing method of the said invention.
And the nonaqueous electrolyte secondary battery of this invention uses the said negative electrode material for secondary batteries of this invention, It is characterized by the above-mentioned.
First, the production method of the present invention will be described in detail.

First, the production method of the present invention includes:
(A) A resin composition and a phosphorus-containing compound are mixed to prepare a phosphorus-containing carbon material precursor.

First, the resin composition used in the production method of the present invention will be described.
Although it does not specifically limit as said resin composition, For example, what is chosen from a thermosetting resin, a thermoplastic resin, or another polymeric material (Hereafter, these may be only called "main component resin.") Can be contained. The main component resins can be used alone or in combination of two or more.
Moreover, a hardening | curing agent, an additive, etc. can be contained together with the said main component resin.

  In the present invention, the above resin composition may contain only one kind of resin as the main component resin, but for convenience, it is also referred to as a resin composition.

  Here, the thermosetting resin is not particularly limited. For example, a phenol resin such as a novolac type phenol resin or a resol type phenol resin, an epoxy resin such as a bisphenol type epoxy resin or a novolac type epoxy resin, a melamine resin, a urea resin, or aniline. Examples thereof include resins, cyanate resins, furan resins, ketone resins, unsaturated polyester resins, and urethane resins. In addition, modified resins in which these are modified with various components can also be used.

  The thermoplastic resin is not particularly limited. For example, polyethylene, polystyrene, polyacrylonitrile, acrylonitrile-styrene (AS) resin, acrylonitrile-butadiene-styrene (ABS) resin, polypropylene, vinyl chloride, methacrylic resin, polyethylene terephthalate, Examples thereof include polyamide, polycarbonate, polyacetal, polyphenylene ether, polybutylene terephthalate, polyphenylene sulfide, polysulfone, polyether sulfone, polyether ether ketone, polyether imide, polyamide imide, polyimide, and polyphthalamide.

  Other polymer compounds are not particularly limited, and examples thereof include polymerizable polymer compounds such as petroleum pitch, coal pitch, and spinning pitch.

When a thermosetting resin is used as the main component resin, the curing agent can be used in combination.
Although it does not specifically limit as a hardening | curing agent used here, For example, in the case of a novolak-type phenol resin, a hexamethylenetetramine, paraform, etc. can be used. In the case of epoxy resins, polyamine compounds such as aliphatic polyamines and aromatic polyamines, acid anhydrides, imidazole compounds, dicyandiamide, novolac type phenol resins and the like can be used.
In addition, even if it is a thermosetting resin that normally uses a predetermined amount of a curing agent, the resin composition used in the present invention may use a smaller amount than usual or may be used without using a curing agent. You can also

As said main component resin used for said resin composition, a thermosetting resin is preferable. Thereby, the remaining carbon rate of a carbon material can be raised more.
And among thermosetting resins, those selected from novolak type phenol resins, melamine resins, furan resins, and aniline resins are preferable. Thereby, a carbon material can be manufactured at a low price.

In addition to the above, an additive can be blended in the resin composition.
Although it does not specifically limit as an additive used here, For example, the carbon material precursor carbonized at 200-800 degreeC, a graphite and graphite modifier, a nitrogen-containing compound, an oxygen-containing compound, an aromatic compound, and nonferrous A metal element etc. can be mentioned.
The above additives may be used alone or in combination of two or more depending on the type and properties of the main component resins used.

  The method for preparing the resin composition is not particularly limited. For example, the main component resins and other components are blended in a predetermined ratio, and these are melt-mixed. These components are used as a solvent. It can be prepared by a method of dissolving and mixing, or a method of pulverizing and mixing these components.

The apparatus for preparing the resin composition is not particularly limited. For example, when melt mixing is performed, a kneading apparatus such as a kneading roll, a single screw or a twin screw kneader can be used. Moreover, when performing melt | dissolution mixing, mixing apparatuses, such as a Henschel mixer and a disperser, can be used, for example. And when performing pulverization mixing, apparatuses, such as a hammer mill and a jet mill, can be used, for example.
The resin composition thus obtained may be one obtained by physically mixing a plurality of types of components, or a part of the resin composition is chemically treated by energy applied in the resin composition preparation stage. It may have been reacted with.

  In the manufacturing method of this invention, a phosphorus containing compound can be mixed with the resin composition demonstrated above, and it can be set as a phosphorus containing carbon material precursor.

Although it does not specifically limit as a phosphorus containing compound used here, Phosphoric acids can be used conveniently. Examples of phosphoric acids include linear polyphosphoric acid such as phosphoric acid (orthophosphoric acid), diphosphoric acid, and triphosphoric acid, cyclic polyphosphoric acid, diphosphorus pentoxide, phosphorous acid, hypophosphorous acid, and the like. A phosphate ester compound is mentioned. These can be used alone or in combination of two or more.
Among these, as the solid phosphorus-containing compound, diphosphorus pentoxide, various phosphate ester compounds, and the like can be suitably used. Moreover, phosphoric acid can be used suitably as a solution-like phosphorus containing compound.

The method for preparing the phosphorus-containing carbon material precursor is not particularly limited. For example, the resin composition and the phosphorus-containing compound are pulverized and mixed, melt-mixed, pulverized and then melt-mixed, or solution. The method of mixing in a state can be mentioned.
Further, as will be described later, after mixing the resin composition and the phosphorus-containing compound, it can be carried out by a method of melting and mixing with heat at the stage of curing treatment or preliminary carbonization treatment.
As the phosphorus-containing carbon material precursor used in the present invention, a material in which the resin composition and the phosphorus-containing compound are substantially uniformly mixed by the above-described methods can be suitably used.

Although it does not specifically limit as the quantity of the phosphorus containing compound used here, It is preferable to set it as 0.1-15 weight% in conversion of a phosphorus component with respect to a resin composition. More preferably, it is 0.5-10.0 weight%. Thereby, a suitable amount of pores can be formed on the carbon material surface in the step (b).
When the amount of the phosphorus-containing compound exceeds the upper limit, the pore volume tends to be small because the effect of phosphorus as a catalyst becomes excessive during the condensation reaction in step (b). On the other hand, if it is less than the above lower limit value, the effect of phosphorus as a catalyst becomes too small, so that an appropriate decrease in the pore volume is difficult to occur, and the pore volume tends to increase. Thus, the pore volume formed on the carbon material surface can be controlled by adjusting the amount of the phosphorus-containing compound relative to the resin composition.

  In the production method of the present invention, the phosphorus-containing carbon material precursor can be prepared by the method described above. In the production method of the present invention, the phosphorus-containing carbon material precursor obtained in this way can be used as it is, or after mixing the resin composition and the phosphorus-containing compound, this is cured, A carbonized product or a product obtained by subjecting it to a preliminary carbonization treatment after a curing treatment can be used.

The curing treatment can be performed when a thermosetting resin or a polymerizable polymer compound is used as the main component resin of the resin composition. The method for the curing treatment is not particularly limited. For example, the curing may be performed by a method in which the resin composition is thermally cured by giving a heat amount capable of a curing reaction, or a method in which a main component resin and a curing agent are used in combination. it can.
Further, the method for the preliminary carbonization treatment is not particularly limited, but a phosphorus-containing carbon material precursor or a material obtained by curing the phosphorus-containing carbon material precursor is, for example, 400 to 600 ° C. at 1 to 200 ° C./hour. The temperature can be raised to 0.1 to 50 hours, preferably 0.5 to 10 hours.

  By performing such curing treatment and / or preliminary carbonization treatment, the phosphorus-containing carbon precursor can be substantially infusible, and the handleability after the step (b) can be improved.

What performed the said hardening process and / or carbonization process can be used by grind | pulverizing this to a suitable particle size after cooling to normal temperature.
Although this particle size is not particularly limited, the average particle size is preferably 1 to 30 μm, more preferably 5 to 20 μm.
As a result, the surface area of the phosphorus-containing carbon material precursor is increased, and when performing carbonization in the step (b) described later, the thermal history and the uniformity of the surface state are improved, and more suitable pores can be formed. it can.

Next, in the production method of the present invention,
(B) The phosphorus-containing carbon material precursor is carbonized.

Although it does not specifically limit as the conditions of the carbonization process in the said (b) process, For example, it heats up at 1-200 degreeC / hour from normal temperature, 0.1 to 50 hours at 800-3000 degreeC, Preferably it is 0.5 For 10 hours. As an atmosphere during the carbonization treatment, for example, an inert atmosphere such as nitrogen or helium gas, or a substantially inert atmosphere in which a trace amount of oxygen is present in the inert gas can be used.
Conditions such as temperature and time during the carbonization can be adjusted as appropriate in order to optimize the characteristics of the carbon material.

Next, in the production method of the present invention,
(C) The treated product after carbonization is washed with water to substantially remove the phosphorus component present at least on the surface of the treated product.

  In the step (d), the method of washing the treated product after carbonization treatment is not particularly limited, but for example, the method is to stir the treated product in water, or to wash the treated product with running water. Can do. Thereby, the phosphorus component which exists in at least the surface site | part of processed material can be substantially dissolved and removed in water, and the carbon material which does not contain an impurity and a foreign material in a surface site | part can be obtained.

The pore volume formed on the surface of the carbon material obtained by the production method of the present invention is not particularly limited, but the pore volume having a pore diameter exceeding 0.33 nm is 0.1 to 50 ml / kg. Is preferred. More preferably, it is 0.1-20 ml / kg.
As a result, when used as a negative electrode material for a secondary battery, the amount of reversible pores can be optimized and the amount of irreversible pores can be reduced, so a secondary battery having high charge / discharge characteristics. A negative electrode material can be obtained.
If the pore volume is smaller than the lower limit, the reversible pores that can occlude lithium are reduced, and the charge / discharge capacity tends to be small. On the other hand, if it is larger than the above upper limit value, since lithium cannot be released after occlusion and irreversible pores are relatively increased, charge / discharge efficiency similarly decreases.

  The reason why the carbon material that can be suitably used for the negative electrode material for secondary batteries is obtained by the production method of the present invention is not clear, but is presumed as follows.

Usually, in the process of carbonizing the thermosetting resin or its cured product, pores are formed on the surface of the carbon material by three-dimensional crosslinking reaction, thermal decomposition reaction, and ring condensation reaction. A carbon material surface with a large variation is formed, and the pore volume itself is also large. This is presumed to be partly due to non-uniform progression of the series of reactions depending on the resin structure and heat treatment method.
On the other hand, in the production method of the present invention, a phosphorus-containing compound is mixed with the resin composition as a phosphorus-containing carbon material precursor, and this is subjected to curing treatment and / or preliminary carbonization treatment as necessary. After that, carbonization is performed. As a result, the phosphorus component functions as a catalyst in the surface portion of the phosphorus-containing carbon material precursor, particularly at the stage where the thermal decomposition reaction or ring condensation reaction occurs, and the condensation of the carbocycle forming the carbon material is promoted. It is done. By this action, it is considered that the series of reactions proceed smoothly, the uniformity of the pore diameter formed on the surface of the carbon material is improved, and the pore volume can be set to a suitable level.
In addition, if necessary, by adjusting the amount of the phosphorus-containing compound to be mixed with the resin composition, the size of the pore volume formed on the surface of the carbon material can be controlled, and the desired battery characteristics can be obtained. It is possible to obtain a corresponding carbon material.
According to the production method of the present invention, for example, compared with a method of controlling the pore volume of the carbon material by means such as increasing the carbonization temperature, the carbon material that is desired is reduced by performing carbonization at a lower temperature. Can be obtained at a cost.
The carbon material thus obtained does not substantially contain impurities at least on the surface thereof, so that the insertion / extraction reaction of lithium ions is rarely inhibited during charge / discharge due to side reactions or the like. By using such a carbon material, a negative electrode material for a nonaqueous electrolyte secondary battery excellent in charge / discharge characteristics can be produced.

In the production method of the present invention, the pore volume is measured by the following method.
Using a pore distribution measuring device “ASAP2010” manufactured by Shimadzu Corporation, a measurement sample (carbon material) was preheated at 623 K under vacuum heating, and then CO ₂ (molecular diameter; 0.33 nm) was used as a measurement gas. The adsorption isotherm at .15 K was measured, and the pore volume of each adsorbed gas was calculated using the Dubinin-Radushkevic equation, and based on this, the pore volume was calculated based on the following equation.
W = W ₀ · exp [− (A / E) n], A = RT [ln (Ps / P)]
W: Energy [ml / g] occupied by adsorbed molecules
E: Adsorption characteristic energy [J / mol]
P: Parallel vapor pressure [mmHg]
T: Adsorption temperature [K]
W ₀ : pore volume [ml / g]
Ps: saturated vapor pressure [mmHg]
n: Structural index = 2 [−]

Next, the negative electrode material for secondary batteries of the present invention will be described.
The negative electrode material for secondary batteries of the present invention is characterized by containing the carbon material obtained by the production method of the present invention.

  The negative electrode material for a secondary battery of the present invention is not particularly limited. For example, a fluorine-based polymer containing polyethylene, polypropylene, etc., a rubbery polymer such as butyl rubber, butadiene rubber, etc. with respect to 100 parts by weight of the carbon material of the present invention. 1 to 30 parts by weight of an organic polymer binder and an appropriate amount of a viscosity adjusting solvent such as N-methyl-2-pyrrolidone and dimethylformamide are added and kneaded to form a paste-like mixture by compression molding, roll molding, etc. Can be obtained by molding into a sheet shape, a pellet shape or the like. Alternatively, a mixture made into a slurry with a viscosity adjusting solvent can be obtained by coating and forming on a current collector such as a copper foil or a nickel foil.

Next, the nonaqueous electrolyte secondary battery of the present invention will be described.
The nonaqueous electrolyte secondary battery of the present invention is characterized by using the secondary battery negative electrode material of the present invention.

When the above-mentioned negative electrode material for a secondary battery is applied to the nonaqueous electrolyte secondary battery of the present invention, it is not particularly limited.For example, the negative electrode material for a secondary battery is disposed to face the positive electrode material via a separator, A nonaqueous electrolyte secondary battery can be obtained by using the electrolytic solution.
Although it does not specifically limit as a positive electrode material, For example, conductive polymers, such as complex oxides, such as lithium cobalt oxide, lithium nickel oxide, and lithium manganese oxide, polyaniline, polypyrrole, etc. can be used. Although it does not specifically limit as a separator, For example, microporous films, such as polyethylene and a polypropylene, a nonwoven fabric, etc. can be used. Although it does not specifically limit as electrolyte solution, For example, what melt | dissolved lithium salt used as electrolyte in a non-aqueous solvent can be used. Although it does not specifically limit as electrolyte, For example, Li
Lithium metal salts such as ClO ₄ and LiPF ₆ , tetraalkylammonium salts, and the like can be used. The non-aqueous solvent is not particularly limited. For example, a mixture of cyclic esters such as propylene carbonate, ethylene carbonate and γ-butyrolactone, chain esters such as dimethyl carbonate and diethyl carbonate, ethers such as dimethoxyethane, and the like. Can be used. A solid electrolyte in which the above salts are mixed with polyethylene oxide, polyacrylonitrile or the like may be used, but is not particularly limited.

  Hereinafter, the present invention will be described by way of examples. However, the present invention is not limited to the examples. In the examples and comparative examples, “part” indicates “part by weight”, and “%” indicates “% by weight”.

The raw materials used in the examples and comparative examples are as follows.
(1) Novolac type phenolic resin: “PR-53195” manufactured by Sumitomo Bakelite Co., Ltd., weight average molecular weight of about 3000
(2) Resol type phenolic resin: “PR-50607B” manufactured by Sumitomo Bakelite Co., Ltd., weight average molecular weight of about 730

1. Production of carbon material <Example 1>
(1) Preparation of Phosphorus-Containing Carbon Material Precursor A resin composition was prepared by pulverizing and mixing 100 parts of a novolak type phenol resin, 10 parts of hexamethylenetetramine, and 6 parts of diphosphorus pentoxide. The obtained resin composition was heated from 100 ° C. over 5 hours, reached 200 ° C., held for another hour and cured, and then pulverized to a mean particle size of 20 μm with a vibration ball mill. A carbon material precursor was obtained.
(2) Production of Carbon Material The phosphorus-containing carbon material precursor obtained above was heated from room temperature at 100 ° C./hour, and after reaching 1200 ° C., it was further held for 10 hours for carbonization treatment. Then, after cooling to normal temperature and using 10 weight part of water with respect to 1 weight part of carbon material, stirring and washing for about 10 minutes, filtration and drying were performed to obtain a carbon material.

<Example 2>
Example 1 (1) Preparation of phosphorus-containing carbon material precursor In the same manner as in Example 1 except that 3 parts of phosphorous pentoxide was used, a phosphorus-containing carbon material precursor and a carbon material were obtained. It was.

<Example 3>
Example 1 (1) Preparation of phosphorus-containing carbon material precursor In the same manner as in Example 1 except that 1 part of phosphorous pentoxide was used, a phosphorus-containing carbon material precursor and a carbon material were obtained. It was.

<Example 4>
Example 1 (1) Preparation of phosphorus-containing carbon material precursor In the same manner as in Example 1 except that 20 parts of diphosphorus pentoxide was used, a phosphorus-containing carbon material precursor and a carbon material were obtained. It was.

<Example 5>
(1) Preparation of Phosphorus-Containing Carbon Material Precursor A resin composition was prepared by mixing 100 parts of water-soluble resol-type phenol resin with 10 parts of phosphoric acid (85 wt% aqueous solution) in terms of solid content. The obtained resin composition was heated from 100 ° C. over 5 hours to remove moisture, and after reaching 200 ° C., it was further cured by holding for 1 hour, and then with an oscillating ball mill to an average particle size of 20 μm. By pulverizing, a phosphorus-containing carbon material precursor was obtained. (2) Production of Carbon Material A carbon material was obtained in the same manner as in Example 1 using the phosphorus-containing carbon material precursor obtained in (1) above.

<Comparative example>
(1) Preparation of composition 100 parts of novolak type phenol resin and 10 parts of hexamethylenetetramine were pulverized and mixed to prepare a resin composition.
The obtained resin composition was heated from 100 ° C. over 5 hours, and after reaching 200 ° C., it was further cured by holding for 1 hour, and then pulverized to an average particle size of 20 μm with a vibration ball mill, A cured product of the composition was obtained.
(2) Production of carbon material The cured product of the resin composition obtained above was heated from room temperature at 10 ° C./hour, reached 1200 ° C., and held for another 10 hours for carbonization treatment, I got the material.

2. Evaluation of Resin Composition and Carbon Material The following evaluation was performed on the phosphorus-containing carbon material precursors and carbon materials obtained in Examples and Comparative Examples.
The results are shown in Table 1.

(1) Blending of resin composition The blending of resin compositions used in Examples and Comparative Examples was shown.

(2) Content of Phosphorus Component of Phosphorus-Containing Carbon Material Precursor It was calculated from the compounding amount of the resin composition used when preparing the phosphorous-containing carbon material precursor and the phosphorous-containing compound.

(3) Evaluation of pore volume of carbon material The pore diameter and pore volume were measured by the following methods.
Using a pore distribution measuring device “ASAP2010” manufactured by Shimadzu Corporation, pre-vacuum heating pretreatment with a measurement sample (carbon material) 623K, then using CO ₂ (molecular diameter: 0.33 nm) as a measurement gas 273. The adsorption isotherm at 15 K was measured, and the pore volume of each adsorbed gas was calculated using the Dubinin-Radushkevic equation, and based on this, the pore volume was calculated based on the following equation.
W = W ₀ · exp [− (A / E) n], A = RT [ln (Ps / P)]
W: Energy [ml / g] occupied by adsorbed molecules
E: Adsorption characteristic energy [J / mol]
P: Parallel vapor pressure [mmHg]
T: Adsorption temperature [K]
W ₀ : pore volume [ml / g]
Ps: saturated vapor pressure [mmHg]
n: Structural index = 2 [−]
R: Gas constant

3. Evaluation as negative electrode material for secondary battery (1) Production of bipolar coin cell for secondary battery evaluation 10 parts of polyvinylidene fluoride as a binder with respect to 100 parts of carbon material obtained in Examples and Comparative Examples, diluted An appropriate amount of N-methyl-2-pyrrolidone as a solvent was added and mixed to prepare a slurry-like negative electrode mixture. The prepared negative electrode slurry-like mixture was applied to both sides of 18 μm copper foil, and then vacuum-dried at 110 ° C. for 1 hour. After vacuum drying, the electrode was pressure-formed by a roll press. This was cut out as a circle having a diameter of 16.156 mm to produce a negative electrode.
The positive electrode was evaluated with a bipolar coin cell using lithium metal. As the electrolytic solution, a solution obtained by dissolving 1 mol / liter of lithium perchlorate in a mixed solution of ethylene carbonate and diethyl carbonate having a volume ratio of 1: 1 was used.

(2) Evaluation of charging capacity and discharging capacity The charging condition was that charging was terminated at a constant current of 25 mA / g until it reached 1 mV, and then the current was attenuated to 1.25 mA / g or less with 1 mV holding. . The discharge conditions were set until the current was attenuated to 1.25 mAh / g or less. The cut-off potential under discharge conditions was 1.5V.

(3) Evaluation of charge / discharge efficiency Based on the value obtained in the above (2), the charge / discharge efficiency was calculated by the following formula.
Charge / discharge efficiency (%) = [discharge capacity / charge capacity] × 100

Each of Examples 1 to 5 is a carbon material obtained by the production method of the present invention. In the evaluation using the carbon material using the carbon material as a negative electrode material of a secondary battery, both the discharge capacity and the charge / discharge efficiency are Good results were obtained as compared with Comparative Example 1 which is a conventional production method.
Since the comparative example did not use phosphorus, the pore volume was large and the charge capacity was the same as that of the example, but the discharge capacity was low, so the charge / discharge efficiency was at a low level.

The carbon material obtained by the method for producing a carbon material according to the present invention can be suitably used for various purposes such as a negative electrode for a lithium ion secondary battery, an electrode for a capacitor, an electrode for electrolysis, and activated carbon. .

Claims (6)

A method for producing a carbon material obtained by carbonizing a resin composition,
(A) mixing the resin composition and the phosphorus-containing compound to prepare a phosphorus-containing carbon material precursor; (b) carbonizing the phosphorus-containing carbon material precursor; and
(C) washing the treated product after carbonization treatment with water to substantially remove phosphorus components present at least on the surface of the treated product;
A method for producing a carbon material, comprising: The method for producing a carbon material according to claim 1, wherein the resin composition has at least one selected from a novolac type phenol resin, a melamine resin, a furan resin, and an aniline resin. The method for producing a carbon material according to claim 1 or 2, wherein the phosphorus-containing compound is mixed with the resin composition in an amount of 0.1 to 15% by weight in terms of a phosphorus component. The method for producing a carbon material according to any one of claims 1 to 3, wherein the carbon material has a pore volume of 0.1 to 50 ml / kg having a pore diameter exceeding 0.33 nm formed on a surface thereof. . A negative electrode material for a secondary battery, comprising a carbon material obtained by the production method according to claim 1. A non-aqueous electrolyte secondary battery using the negative electrode material for a secondary battery according to claim 5.