JP2024037197A - Carbonaceous material, negative electrode for power storage device, power storage device, and method for manufacturing carbonaceous material - Google Patents

Abstract

To provide a carbonaceous material capable of providing a power storage device which has a high discharge capacity and excellent current efficiency per weight and can maintain a high discharge capacity even after repeated charging and discharging when applied as a negative electrode layer and being excellent in coatability capable of improving the yield of an electrode.SOLUTION: A carbonaceous material has a nitrogen element content of 1.0 mass% or more, an oxygen element content of 0.6 mass% or more and 2.0 mass% or less, a hydrogen element content of 0.1 mass% or less, and a phosphorus element content of 0.1 mass% or more and 2.0 mass% or less by X-ray fluorescence analysis.SELECTED DRAWING: None

Description

The present invention relates to a carbonaceous material, a negative electrode for a power storage device, a power storage device, and a method for manufacturing a carbonaceous material.

Electricity storage devices are devices such as secondary batteries and capacitors that utilize electrochemical phenomena, and are widely used. For example, lithium ion secondary batteries, which are one type of power storage device, are widely used in small portable devices such as mobile phones and notebook computers. Non-graphitizable carbon, which can be doped (charged) and dedoped (discharged) with lithium in an amount exceeding the theoretical capacity of graphite of 372 mAh/g, has been developed as a negative electrode material for lithium ion secondary batteries (for example, Patent Document 1 ), has been used.

Non-graphitizable carbon can be obtained from, for example, petroleum pitch, coal pitch, phenolic resin, or plants as a carbon source. Among these carbon sources, plant-derived raw materials such as sugar compounds are attracting attention because they can be continuously and stably supplied through cultivation and can be obtained at low cost. In addition, since carbonaceous materials obtained by firing plant-derived carbon raw materials have many pores, good charge and discharge capacity is expected (for example, Patent Document 1 and Patent Document 2).

Further, as carbonaceous materials that can be used as negative electrodes of lithium ion secondary batteries and the like, carbonaceous materials adjusted to contain specific amounts of various elements other than carbon (Patent Document 3) are known.

International Publication No. 2019/009332 International Publication No. 2019/009333 Japanese Patent Application Publication No. 2009-200014

Although it is known that the carbonaceous materials described in Patent Documents 1 to 3 are used as negative electrode materials that exhibit high charge/discharge capacity, it is necessary to further increase the capacity and current efficiency of the negative electrode in various applications of electricity storage devices. There is still a need for improvements in Furthermore, it is required to maintain high discharge capacity even after repeated charging and discharging. Furthermore, when coating as an electrode, spots due to agglomeration of the carbonaceous material may be formed on the electrode, which may reduce the yield of the electrode. Therefore, the present invention provides an electricity storage device that has high discharge capacity per weight and high current efficiency when applied as a negative electrode layer, and can maintain high discharge capacity even after repeated charging and discharging. The purpose of the present invention is to provide a carbonaceous material with excellent coating properties that can improve the yield of electrodes. Another object of the present invention is to provide a negative electrode for a power storage device including such a carbonaceous material, and a power storage device including such a negative electrode for a power storage device.

As a result of intensive research by the present inventors, it has been found that by setting the nitrogen element content, oxygen element content, hydrogen element content, and phosphorus element content in the carbonaceous material within predetermined ranges, a high discharge capacity per weight can be achieved. A carbonaceous material that has excellent current efficiency, is suitable for power storage devices that can maintain high discharge capacity even after repeated charging and discharging, and has excellent coating properties that can improve the yield of electrodes. I found out that I can get .

That is, the present invention includes the following preferred embodiments.
[1] According to elemental analysis, the nitrogen element content is 1.0 mass% or more, the oxygen amount is 0.60 mass% or more and 2.0 mass% or less, and the hydrogen element content is 0.1 mass% or less A carbonaceous material having a phosphorus element content of 0.1% by mass or more and 2.0% by mass or less as determined by X-ray fluorescence analysis.
[2] The carbonaceous material according to [1], which has a carbon plane spacing (d ₀₀₂ ) of 3.65 Å or more as measured by X-ray diffraction.
[3] The carbonaceous material according to [1] or [2], wherein the half-width value of the peak near 1360 cm ^-1 is 210 cm ^-1 or more in the Raman spectrum observed by laser Raman spectroscopy.
[4] The carbonaceous material according to any one of [1] to [3], which is a carbonaceous material for a negative electrode of an electricity storage device.
[5] A negative electrode for an electricity storage device, comprising the carbonaceous material according to any one of [1] to [4].
[6] An electricity storage device comprising the negative electrode for an electricity storage device according to [5].
[7] The following steps:
(1) A step of mixing a compound having a sugar skeleton and a nitrogen-containing compound to obtain a mixture;
(2) heat-treating the mixture at 500 to 900°C under an inert gas atmosphere to obtain a carbide;
(3) a step of pulverizing and/or classifying the carbide; (4) a step of heat-treating the pulverized and/or classified carbide at 1100 to 1600°C in an inert gas atmosphere; At least a step of mixing a carboxylic acid compound or a compound having a saccharide skeleton and heat-treating the mixture at 100°C to 300°C to obtain a carbonaceous material,
(a) Prior to the heat treatment in step (4), it includes a step of mixing a compound having a sugar skeleton, a mixture containing the compound, or a carbonized product of the mixture, and a phosphorus-containing compound, [1] to The method for producing a carbonaceous material according to any one of [4].

According to the present invention, it is suitable for an electricity storage device that has a high discharge capacity per weight, excellent current efficiency, and can maintain a high discharge capacity even after repeated charging and discharging. It is possible to provide a carbonaceous material with excellent coating properties that can be improved. In this specification, the total efficiency is defined as the product of the initial current efficiency and the capacity retention rate after repeated charging and discharging, and a battery with a high total efficiency is considered to be a battery excellent in the above characteristics.

Embodiments of the present invention will be described in detail below. Note that the present invention is not intended to be limited to the following embodiments.

In this specification, an electricity storage device refers to any device that includes a negative electrode containing a carbonaceous material and utilizes electrochemical phenomena. Specifically, power storage devices include, for example, secondary batteries such as lithium ion secondary batteries, nickel hydride secondary batteries, and nickel cadmium secondary batteries, and capacitors such as electric double layer capacitors, which can be used repeatedly by charging. Including etc. Among these, power storage devices are secondary batteries, especially non-aqueous electrolyte secondary batteries (e.g. lithium ion secondary batteries, sodium ion batteries, lithium sulfur batteries, lithium air batteries, all-solid-state batteries, organic radical batteries, etc.). Among them, it may be a lithium ion secondary battery.

The carbonaceous material of the present invention has high discharge capacity per weight, excellent current efficiency, and is suitable for providing an electricity storage device that can maintain high discharge capacity even after repeated charging and discharging. It is a carbonaceous material that not only has excellent coating properties, but also has excellent coating properties that can improve the yield of electrodes. That is, the carbonaceous material of the present invention has a nitrogen element content of 1.0 mass% or more, an oxygen content of 0.60 mass% or more and 2.0 mass% or less, and a hydrogen element content of 0. .1 mass% or less, and the phosphorus element content as determined by fluorescent X-ray analysis is 0.1 mass% or more and 2.0 mass% or less.

The phosphorus element content of the carbonaceous material of the present invention as determined by X-ray fluorescence analysis is 0.1% by mass or more and 2.0% by mass or less. The phosphorus element content is an analytical value obtained by subjecting a carbonaceous material to fluorescent X-ray analysis. When the phosphorus element content is less than 0.1% by mass, the number of sites for adsorbing and desorbing lithium ions during charging and discharging decreases, making it impossible to sufficiently increase the discharge capacity and current efficiency per weight. The phosphorus element content is preferably 0.3% by mass or more, more preferably 0.5% by mass or more, still more preferably 0.7% by mass or more, and even more preferably from the viewpoint of easily increasing discharge capacity and current efficiency. is 0.9% by mass or more, particularly preferably 1.2% by mass or more. In addition, if the phosphorus element content exceeds 2.0% by mass, sites that irreversibly adsorb lithium ions are likely to occur, making it difficult to maintain capacity during repeated charging and discharging, making it difficult to maintain high discharge capacity. becomes difficult. From the viewpoint of easily maintaining a high discharge capacity even after repeated charging and discharging, the phosphorus element content of the carbonaceous material of the present invention determined by fluorescent X-ray analysis is 2.0% by mass or less, preferably 1.9% by mass or less. , more preferably 1.8% by mass or less, still more preferably 1.75% by mass or less. The phosphorus element content of carbonaceous materials determined by X-ray fluorescence analysis can be determined by adjusting the amount of phosphorus element-containing compounds that may be added when manufacturing carbonaceous materials, and by adjusting the temperature and time of heat treatment. , can be adjusted within the above range.

The nitrogen element content according to elemental analysis of the carbonaceous material of the present invention is 1.0 mass % or more, and the hydrogen element content is 0.1 mass % or less. The nitrogen element content and the hydrogen element content are analytical values obtained by elemental analysis of a carbonaceous material. The carbonaceous material contains 1.0% by mass or more of the nitrogen element and the hydrogen element content is 0.1% by mass or less, thereby creating a carbonaceous material containing only the phosphorus element or a carbonaceous material with a high hydrogen element content. It has been found that the discharge capacity and current efficiency can be further increased compared to the conventional method, and that the high discharge capacity can be maintained even after repeated charging and discharging. In a carbonaceous material that does not contain nitrogen but contains phosphorus, current efficiency may decrease because phosphorus is easily oxidized. On the other hand, carbonaceous materials containing both nitrogen and phosphorus elements tend to undergo reduction of the phosphorus element, which tends to reduce the oxygen element content, for reasons that are not clear, and can increase current efficiency. it is conceivable that. In addition, when the nitrogen element content is less than 1.0% by mass, the carbon surfaces are close to each other, which reduces the number of sites for adsorbing and desorbing lithium ions during charging and discharging, so this also reduces the discharge capacity per weight. It is considered that it is not possible to sufficiently increase the In addition, in the case of carbonaceous materials with a hydrogen element content of more than 0.1% by mass, side reactions such as reactions between Li ions and electrolyte tend to occur, and as a result, the irreversible capacity of Li ions increases. It is thought that it becomes difficult to maintain a high discharge capacity even after repeated charging and discharging. On the other hand, it is considered that such side reactions can be suppressed by having a hydrogen element content of 0.1% by mass or less.

The nitrogen element content is preferably 1.10% by mass or more, more preferably 1.15% by mass or more, and even more preferably 1.20% by mass or more from the viewpoint of easily increasing discharge capacity and current efficiency. Further, the upper limit of the nitrogen element content is preferably 8.0% by mass or less, more preferably 6.0% by mass or less, and even more preferably is 5.0% by mass or less, even more preferably 4.0% by mass or less, especially preferably 2.0% by mass or less, especially more preferably 1.5% by mass or less, even more preferably 1.30% by mass or less, More preferably, it is 1.28% by mass or less. The nitrogen element content determined by elemental analysis of the carbonaceous material can be determined within the above range by adjusting the amount of nitrogen-containing compounds that may be added when manufacturing the carbonaceous material, adjusting the temperature and time of heat treatment, etc. can be adjusted to

The hydrogen element content is preferably 0.10% by mass or less, more preferably 0.08% by mass or less, and even more preferably 0.06% by mass, from the viewpoint of suppressing discharge capacity reduction and improving current efficiency when charging and discharging are repeated. It is not more than 0.05% by mass, even more preferably not more than 0.05% by mass. Further, the lower limit of the hydrogen element content is 0% by mass or more. The hydrogen element content determined by elemental analysis of carbonaceous materials can be determined by adjusting the amount of nitrogen-containing compounds and phosphorus-containing compounds that may be added when manufacturing carbonaceous materials, and by adjusting the temperature and time of heat treatment. It can be adjusted within the above range.

The oxygen element content of the carbonaceous material of the present invention as determined by elemental analysis is 0.60% by mass or more and 2.0% by mass or less. By adjusting the oxygen element content within the above range, it is possible not only to have high discharge capacity and excellent current efficiency, but also to maintain high discharge capacity even after repeated charging and discharging. It becomes possible to provide a carbonaceous material with excellent coating properties that can improve the yield of carbonaceous materials. From the viewpoint of coatability, the lower limit of the oxygen amount is preferably 0.70% by mass or more, more preferably 0.80% by mass or more, and still more preferably 0.90% by mass or more. Further, from the viewpoint of improving discharge capacity and current efficiency, the upper limit of the oxygen element content is preferably 4.0% by mass or less, more preferably 3.0% by mass or less, still more preferably 2.0% by mass or less, and It is more preferably 1.5% by mass or less, particularly preferably 1.0% by mass or less. The oxygen element content determined by elemental analysis of the carbonaceous material is determined by adjusting the amount of nitrogen-containing compounds that may be added when manufacturing the carbonaceous material, the amount of phosphorus-containing compounds that may be added, and the temperature and time of heat treatment. In addition, the above range can be adjusted by adjusting the amount of additives added in the post-heat treatment described later, the temperature and time of the heat treatment.

The carbon plane spacing (d ₀₀₂ ) measured by X-ray diffraction of the carbonaceous material of the present invention is determined by widening the carbon plane spacing, making it easier for lithium ions to move efficiently, and by sufficiently developing micropores to form clusters. From the viewpoint of increasing the occlusion sites of lithium chloride and easily increasing the discharge capacity and current efficiency per weight, preferably 3.65 Å or more, more preferably 3.68 Å or more, still more preferably 3.70 Å or more, and even more preferably The thickness is 3.71 Å or more, particularly preferably 3.73 Å or more. In addition, the upper limit of the carbon plane spacing ( _d002 ) is determined from the viewpoint that by appropriately reducing _d002 , the volume of the carbonaceous material can be appropriately reduced, the effective capacity per volume can be increased, and the discharge capacity per volume can be easily increased. , preferably 4.00 Å or less, more preferably 3.95 Å or less, still more preferably 3.90 Å or less, and even more preferably 3.85 Å or less. The carbon spacing (d ₀₀₂ ) is measured by X-ray diffraction measurement using the Bragg equation, and specifically, by the method described in Examples. The carbon spacing (d ₀₀₂ ) is adjusted within the above range by adjusting the amount of nitrogen-containing compound that may be added when manufacturing the carbonaceous material, adjusting the temperature and time of heat treatment, etc. be able to.

In a preferred embodiment of the present invention, the half-value width of the peak near 1360 cm ^-1 in the Raman spectrum observed by laser Raman spectroscopy of the carbonaceous material of the present invention is the same as that of the electrode fabricated using the carbonaceous material. From the viewpoint of easily increasing the discharge capacity, it is preferably 210 cm ^-1 or more, more preferably 220 cm ^-1 or more, even more preferably 230 cm ^-1 or more, and even more preferably 240 cm ^-1 or more. Here, the peak near 1360 cm ^-1 is a Raman peak generally referred to as the D band, and is a peak resulting from disorder/defects in the graphite structure. The peak around 1360 cm ⁻¹ is usually observed in the range of 1345 cm ⁻¹ to 1375 cm ⁻¹ , preferably 1350 cm ⁻¹ to 1370 cm ⁻¹ . The Raman spectrum is measured using a Raman spectrometer under the conditions described in Examples, for example. The value of the half-width of the peak near 1360 cm ^-1 can be determined by adjusting the amount of nitrogen-containing compounds that may be added when manufacturing the carbonaceous material, and by adjusting the temperature and time of heat treatment. Can be adjusted to the range.

In a preferred embodiment of the present invention, the half-width value of the peak near 1650 cm ⁻¹ in the Raman spectrum observed by laser Raman spectroscopy of the carbonaceous material of the present invention is the same as that of the electrode made using the carbonaceous material. From the viewpoint of easily increasing the discharge capacity per weight, it is preferably 98 cm ^-1 or more, more preferably 100 cm ^-1 or more, even more preferably 101 cm ^-1 or more, and even more preferably 102 cm ^{-1 or} more. Here, the peak near 1650 cm ^-1 is a Raman peak generally referred to as the G band, and is a peak caused by disorder/defects in the graphite structure. The peak around 1650 cm ^-1 is usually observed in the range of 90 cm ^-1 to 120 cm ^-1 , preferably in the range of 100 cm ^-1 to 110 cm ^-1 . The Raman spectrum is measured using a Raman spectrometer under the conditions described in Examples, for example. The value of the half-width of the peak near 1650 cm ^-1 can be determined by adjusting the amount of nitrogen-containing compounds that may be added when producing the carbonaceous material, and by adjusting the temperature and time of heat treatment. Can be adjusted to the range.

In the carbonaceous material of the present invention, the carbonaceous material The true density by the butanol immersion method is preferably 1.50 g/cc or more, more preferably 1.51 g/cc or more, still more preferably 1.52 g/cc or more, even more preferably 1.55 g/cc or more. , preferably 1.65 g/cc or less, more preferably 1.64 g/cc or less, even more preferably 1.62 g/cc or less, even more preferably 1.60 g/cc or less.

In the carbonaceous material of the present invention, from the viewpoint of easily increasing the electrode density, the tap bulk density of the carbonaceous material is preferably 0.70 g/cc or more, more preferably 0.72 g/cc or more, and still more preferably 0.70 g/cc or more. It is 75 g/cc or more, even more preferably 0.78 g/cc or more, particularly preferably 0.80 g/cc or more. In addition, the tap bulk density is preferably 1.0 g/cc or less, more preferably 0.97 g/cc or less, and even more preferably 0.95 g/cc, from the viewpoint of liquid absorption of the electrolyte when making the electrode. cc or less, even more preferably 0.93 g/cc or less, particularly preferably 0.91 g/cc or less. The tap bulk density of the carbonaceous material is determined by repeating the step of letting a cylindrical glass container with a diameter of 1.8 cm filled with the carbonaceous material pass through a sieve with an opening of 300 μm and freely fall from a height of 5 cm 100 times. As a set, measurements are repeated until the rate of change in density determined from the volume and mass of the carbonaceous material becomes 2% or less before and after one set of operations.

In the carbonaceous material of the present invention, from the viewpoint of easily increasing the electrode density, the ratio D ₈₀ /D 20 of D ₈₀ to D ₂₀ in the volume-based particle size distribution measured by the laser diffraction scattering particle size distribution measurement method of the _carbonaceous material is preferably is 3.5 or more, more preferably 4.0 or more, even more preferably 4.5 or more, even more preferably 5.0 or more, particularly preferably 5.5 or more, particularly preferably 6.0 or more, From the same viewpoint, it is preferably 18 or less, more preferably 16 or less, and even more preferably 15 or less. D ₈₀ /D ₂₀ is a volume-based particle size distribution measured by a laser diffraction scattering particle size distribution measurement method, which can be measured using a particle size/particle size distribution measuring device using a carbonaceous material dispersion as a measurement sample. In the particle size distribution, the particle diameter at which the cumulative volume is 80% is D ₈₀ , and the particle diameter at which the cumulative volume is 20% is D ₂₀ .

In the carbonaceous material of the present invention, from the viewpoint of easily increasing the electrode density, the circularity measured for particles having a diameter of 5 μm or more in a circle corresponding to the projected area by a flow type particle image analyzer of the carbonaceous material is preferably 0.70 or more, more preferably 0.71 or more, still more preferably 0.72 or more, even more preferably 0.73 or more, and from the same point of view, preferably 0.99 or less, more preferably 0.98 Below, it is more preferably 0.96 or below. The circularity is determined by using a dispersion of a carbonaceous material as a measurement sample, obtaining a projected image of the particle using a flow-type particle image analyzer, and calculating, for each particle in the projected image, an equivalent circle with the same projected area. Calculate the circularity per particle using the following formula: Circularity = (D / M) ² , where the diameter is Dμm and the length at which the distance between two parallel lines sandwiching the particle image is maximum is Mμm. The circularity per particle is the average value of the circularity obtained by measuring, for example, 5,000 or more, preferably 10,000 or more particles having D of 5 μm or more.

The method for producing a carbonaceous material of the present invention is not particularly limited as long as a carbonaceous material having the above-mentioned characteristics can be obtained. However, a compound serving as a carbon source and a nitrogen-containing compound are mixed, and the resulting mixture is heated to 500% Heat treatment is carried out in an inert gas atmosphere at a temperature of ℃ to 900℃, followed by pulverization and/or classification, and the resulting charred material is further heat-treated at 1100 to 1600℃, and a carboxylic acid compound or saccharide skeleton is added to the resulting heat-treated product. Examples include a method in which a compound having a phosphorus-containing compound is mixed and heat treated at 100°C to 300°C, which includes a step of mixing with a phosphorus-containing compound before the heat treatment at 1100 to 1600°C. The compound serving as the carbon source used as a raw material is not particularly limited as long as a carbonaceous material satisfying the above characteristics can be obtained, but from the viewpoint of easily adjusting the above characteristics of the carbonaceous material to a preferable range, it is preferable to use a compound having a saccharide skeleton. It is a compound that has Therefore, the carbonaceous material of the present invention is preferably a sugar-derived carbonaceous material. A production method using a compound having a saccharide skeleton as a carbon source will be described below.

In a preferred embodiment of the present invention, the method for producing a carbonaceous material of the present invention includes the following steps:
(1) A step of mixing a compound having a sugar skeleton and a nitrogen-containing compound to obtain a mixture;
(2) heat-treating the mixture at 500 to 900°C under an inert gas atmosphere to obtain a carbide;
(3) A step of pulverizing and/or classifying the carbide, and (4) a step of heat-treating the pulverized and/or classified carbide at 1100 to 1600°C in an inert gas atmosphere. At least a step of mixing a carboxylic acid compound or a compound having a saccharide skeleton and heat-treating the mixture at 100°C to 300°C to obtain a carbonaceous material,
(a) Prior to the heat treatment in step (4) above, it includes a step of mixing a compound having a sugar skeleton, a mixture containing the compound, or a carbonized product of the mixture, and a phosphorus-containing compound. The present invention also provides a method for producing the above carbonaceous material.

Further, the present invention further includes a step (4') of carrying out the step (4) in the presence of a volatile organic substance, or performing a further heat treatment in the presence of a volatile organic substance after the step (4). , also provides a method for manufacturing the above carbonaceous material. In addition, when performing step (4) in the presence of volatile organic substances, or when performing step (4'), the heat treatment is carried out under conditions such that volatile substances derived from volatile organic substances generated by heat treatment are present. Set temperature. Although it is thought that volatile substances derived from volatile organic substances adhere to the surface of the carbonaceous material in step (4) or step (4'), the present invention is not limited to such a mechanism.

Step (1) is a step of mixing a compound having a saccharide skeleton and a nitrogen-containing compound to obtain a mixture. Examples of compounds with a sugar skeleton that can be used as raw materials include monosaccharides such as glucose, galactose, mannose, fructose, ribose, and glucosamine, and disaccharides such as sucrose, trehalose, maltose, cellobiose, maltitol, lactobionic acid, and lactosamine. , starch, glycogen, agarose, pectin, cellulose, chitin, chitosan, oligosaccharides, xylitol, and other polysaccharides. As the compound having a saccharide skeleton, one type of these compounds may be used, or two or more types may be used in combination. Among these compounds having a saccharide skeleton, starch is preferred because it is easily available in large quantities. Examples of the starch include corn starch, potato starch, wheat starch, rice starch, tapioca starch, sago starch, sweet potato starch, mylostarch, kudzu starch, bracken starch, lotus root starch, mung bean starch, and potato starch. These starches may be physically, enzymatically, or chemically processed, and include starches processed into pregelatinized starch, phosphoric acid crosslinked starch, acetate starch, hydroxypropyl starch, oxidized starch, dextrin, etc. Good too. Corn starch, wheat starch, and pregelatinized starches thereof are preferred as starches because of their availability and low cost.

In a preferred embodiment of the production method of the present invention, from the viewpoint of easily increasing the density of an electrode obtained from a carbonaceous material, as a compound having a saccharide skeleton, a compound obtained by observing a cross section of a particle of the compound with a secondary electron microscope is used. In the image, when 20 particles with a cross-sectional area of 3 μm ² to 100 μm ² are arbitrarily selected, the number of particles having voids of 1 μm ² or more is preferably 3 or less, more preferably 2 or less, and even more preferably Preferably, one or less compounds are used. When producing a carbide using such a compound with few voids as a raw material, additional treatment such as step (b) described below is usually not necessary.

The nitrogen-containing compound that can be used in step (1) is not particularly limited as long as it has a nitrogen atom in its molecule, but includes, for example, inorganic ammonium salts such as ammonium chloride, ammonium sulfate, ammonium carbonate, and ammonium nitrate, ammonium formate, and acetic acid. Organic ammonium salts such as ammonium, ammonium oxalate, diammonium hydrogen citrate, aromatic amine hydrochlorides such as aniline hydrochloride and aminonaphthalene hydrochloride, melamine, pyrimidine, pyridine, pyrrole, imidazole, indole, urea, cyanuric acid, Examples include nitrogen-containing organic compounds such as benzoguanamine. As the nitrogen-containing compound, one type of these nitrogen-containing compounds may be used, or two or more types may be used in combination. Among these nitrogen-containing compounds, nitrogen-containing compounds with a high intramolecular nitrogen content are preferred, from the viewpoint that a large amount of nitrogen element is easily incorporated into the carbonaceous material, and for example, melamine and urea are preferred. The nitrogen-containing compound is preferably a compound whose volatilization temperature is preferably 100°C or higher, more preferably 150°C or higher, from the viewpoint of reaction with the saccharide compound during the heat treatment process.

The mixing ratio of the compound having a saccharide skeleton and the nitrogen-containing compound is not particularly limited, and may be adjusted as appropriate so as to obtain a carbonaceous material having desired characteristics. For example, increasing the amount of nitrogen-containing compounds tends to increase the nitrogen element content contained in the carbonaceous material.

In a preferred embodiment of the present invention, the amount of the compound having a saccharide skeleton contained in the mixture obtained in step (1) is preferably 50 to 99% based on the total amount of the compound having a saccharide skeleton and the nitrogen-containing compound. % by mass, more preferably 80 to 95% by mass. Further, the amount of the nitrogen-containing compound contained in the mixture is preferably 1 to 30% by mass, more preferably 3 to 15% by mass, based on the total amount of the compound having a saccharide skeleton and the nitrogen-containing compound. Further, the amount of the nitrogen-containing compound mixed in step (1) is preferably 0.03 to 0.30 mol, more preferably The amount is 0.05 to 0.20 mol, more preferably 0.07 to 0.15 mol.

In step (1), when the carbon precursor and the nitrogen-containing compound are mixed to obtain a mixture, at least one crosslinking agent may be further mixed. A crosslinking agent is a compound capable of crosslinking a compound having a saccharide skeleton used as a raw material, and is a compound that can crosslink a compound having a saccharide skeleton used as a raw material. It acts as a catalyst to promote the reaction of nitrogen-containing compounds, or itself crosslinks sugar compounds and/or nitrogen-containing compounds. Compounds having a saccharide skeleton are often melted, fused, foamed, etc. during the firing process, and as a result, the resulting carbonaceous material often has a flat shape rather than a spherical shape. When firing is performed using a crosslinking agent, it is easy to suppress the fusion and foaming of the raw materials, and as a result, it is easy to improve the density of the electrode obtained using the obtained carbonaceous material.

When using a crosslinking agent, the type thereof is not particularly limited, but for example, formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, undecanoic acid, lauric acid, myristic acid, etc. acids, aliphatic monocarboxylic acids such as palmitic acid, stearic acid, linoleic acid, oleic acid, aromatic monocarboxylic acids such as benzoic acid, salicylic acid, toluic acid, oxalic acid, malonic acid, succinic acid, glutaric acid , adipic acid, fumaric acid, maleic acid, phthalic acid, terephthalic acid, etc.; hydroxycarboxylic acids such as lactic acid, tartaric acid, citric acid, malic acid, etc.; carboxylic acids such as ethylenediaminetetraacetic acid, p-toluenesulfonic acid , sulfonic acids such as methanesulfonic acid; amino acids such as glycine, alanine, valine, leucine, isoleucine, serine, threonine, cysteine, methionine, asparagine, glutamine, proline, phenylalanine, tyrosine, tryptophan; hydrochloric acid, sulfuric acid, etc. When using a crosslinking agent, one type of these crosslinking agents may be used, or two or more types may be used in combination. Among these crosslinking agents, polyhydric carboxylic acids and hydroxycarboxylic acids are preferred from the viewpoint of suppressing melting and foaming of raw materials in the step of heat treating to obtain carbide, and among them, succinic acid, adipic acid, and citric acid are more preferred. preferable.

Furthermore, when using a crosslinking agent, the amount thereof is preferably 1 to 30% by mass, more preferably 3 to 30% by mass, based on the total amount of the compound having a saccharide skeleton, the nitrogen-containing compound, and the crosslinking agent contained in the mixture. It is 10% by mass. When adding a crosslinking agent, increasing the amount of crosslinking agent tends to increase the true density of the carbonaceous material.

Next, in step (2), the mixture obtained in step (1) is heat-treated at 500 to 900° C. in an inert gas atmosphere to obtain a carbide. The heat treatment temperature in step (2) is preferably 550 to 850°C, more preferably 600 to 800°C. Further, the temperature increase rate until the above heat treatment temperature (achieved temperature) is reached is 50°C/hour or more, preferably 50°C/hour to 200°C/hour. The heat treatment time is usually 5 minutes or more, preferably 5 minutes to 2 hours, more preferably 10 minutes to 1 hour, and even more preferably 30 to 1 hour. When the heat treatment temperature and time are within the above ranges, it is easy to control the carbonization of the compound having a saccharide skeleton, and it is easy to adjust the above characteristic values of the carbonaceous material to a desired range. Here, the heat treatment temperature may be a constant temperature, but is not particularly limited as long as it is within the above range. Step (2) is also referred to as a first firing step.

Step (2) is performed under an inert gas atmosphere. As long as the step is carried out in an inert gas atmosphere, the inert gas may or may not be actively supplied. Examples of the inert gas include argon gas, helium gas, and nitrogen gas, with nitrogen gas being preferred. Through such a heat treatment step, a carbide, which is a precursor for providing a carbonaceous material, is obtained.

In step (3), the obtained carbide is crushed and/or classified. The method of pulverization and classification is not particularly limited, and may be carried out by a conventional method, such as a method using a ball mill or a jet mill. By pulverizing and/or classifying the carbide, aggregates generated by the heat treatment in step (2) can be disintegrated or removed.

In step (4), the pulverized and/or classified carbide is heat-treated at 1100 to 1600° C. in an inert gas atmosphere. The heat treatment temperature in step (4) is preferably 1200 to 1400°C, more preferably 1210 to 1400°C, even more preferably 1230 to 1350°C, even more preferably 1250 to 1300°C. Note that in this specification, heat treatment at 1100 to 1600°C means maintaining a temperature of 1100 to 1600°C for 1 minute or more. The temperature increase rate until the above heat treatment temperature (achieved temperature) is reached is 50°C/hour or more, preferably 50°C/hour to 200°C/hour. Further, the heat treatment time is such that the holding time at the final temperature is 1 minute or more, preferably 5 minutes to 2 hours, more preferably 10 minutes to 1 hour, and even more preferably 10 minutes to 30 minutes. If the heat treatment temperature and time are within the above range, the above characteristic values of the carbonaceous material finally obtained can be easily adjusted to a desired range. Here, the heat treatment temperature may be a constant temperature, but is not particularly limited as long as it is within the above range. Step (4) is also referred to as a second firing step.

In step (5), the carbonaceous material of the present invention is prepared by mixing a carboxylic acid compound or a compound having a saccharide skeleton with the heat-treated product obtained in step (4) and heat-treating the mixture at 100°C to 300°C. Obtainable. Step (5) is also referred to as a post-heat treatment step.

The carboxylic acid compound added in step (5) is not particularly limited, but for example, formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, undecanoic acid, lauric acid. , aliphatic monocarboxylic acids such as myristic acid, palmitic acid, stearic acid, linoleic acid, oleic acid, aromatic monocarboxylic acids such as benzoic acid, salicylic acid, toluic acid, oxalic acid, malonic acid, succinic acid, glutaric acid. Examples include polyhydric carboxylic acids such as adipic acid, fumaric acid, maleic acid, phthalic acid, and terephthalic acid, hydroxycarboxylic acids such as lactic acid, tartaric acid, citric acid, and malic acid, and carboxylic acids such as ethylenediaminetetraacetic acid. As the carboxylic acid compound, one type of these compounds may be used, or two or more types may be used in combination. Among these additives, adipic acid, citric acid, and succinic acid are more preferred in view of their resistance to volatilization during heat treatment and their mixability.

A compound having a saccharide skeleton can also be used as the compound added in step (5). Examples of compounds having a sugar skeleton include monosaccharides such as glucose, galactose, mannose, fructose, ribose, and glucosamine, disaccharides such as sucrose, trehalose, maltose, cellobiose, maltitol, lactobionic acid, and lactosamine, starch, glycogen, Examples include polysaccharides such as agarose, pectin, cellulose, chitin, chitosan, oligosaccharides, and xylitol. As the compound having a saccharide skeleton, one type of these compounds may be used, or two or more types may be used in combination. Among these compounds having a saccharide skeleton, glucose, fructose, and starch are more preferable in consideration of availability.

Although the details of the effect of adding a carboxylic acid compound or a compound having a saccharide skeleton and heat treatment are not clear, the carboxylic acid compound or the compound having a saccharide skeleton reacts with the surface of the heat-treated product obtained in step (4), and the surface It is thought that coating properties are improved by changing the conditions.

The amount of the carboxylic acid compound or compound having a saccharide skeleton added in step (5) is not particularly limited, but is preferably 5% by mass or less based on the heat-treated product obtained in step (4). If the amount of the added compound is large, not only will it react on the surface of the heat-treated product, but also the decomposition products of the compound itself will remain, which may cause a decrease in the performance of the carbonaceous material.

The heat treatment temperature in step (5) is 100°C to 300°C. Although the appropriate temperature differs depending on the additive used, it is generally preferable to carry out the reaction at a temperature higher than the melting point or decomposition temperature of the added compound. Further, the rate of temperature increase until the above heat treatment temperature (achieved temperature) is reached is 50°C/hour or more, preferably 50°C/hour to 600°C/hour. The heat treatment time is usually 5 minutes or more, preferably 5 minutes to 10 hours, more preferably 10 minutes to 5 hours, and even more preferably 30 to 3 hours. When the heat treatment temperature and time are within the above ranges, it is easy to control the reaction of the compound added to the surface of the heat-treated product, and it is easy to adjust the characteristic values of the carbonaceous material to a desired range. Here, the heat treatment temperature may be a constant temperature, but is not particularly limited as long as it is within the above range. Further, step (5) may be performed under an inert gas atmosphere or under an oxygen-existing atmosphere.

In the production method of the present invention, before performing heat treatment at 1100 to 1600°C in step (4), a compound having a saccharide skeleton, a mixture containing the compound, or a carbonized product of the mixture, and a phosphorus-containing compound are mixed. Including step (a). By manufacturing the carbonaceous material by the manufacturing method including step (a), the phosphorus element can be included in the carbonaceous material. The presence of nitrogen and phosphorus elements in the specified amounts in the carbonaceous material and the hydrogen element content within the specified range result in high discharge capacity per weight and excellent current, although the reason is not clear. It is possible to provide a carbonaceous material suitable for power storage devices that has efficiency and can maintain high discharge capacity even after repeated charging and discharging.

Step (a) may be carried out by mixing the compound having a saccharide skeleton and the phosphorus-containing compound used in step (1), or by mixing the compound having a saccharide skeleton and the nitrogen-containing compound in step (1). It may be carried out by also mixing the phosphorus-containing compound when obtaining the mixture in step (1), it may be carried out by mixing the mixture obtained in step (1) and the phosphorus-containing compound, or it may be carried out in step (2). It may be carried out by mixing the carbide obtained in step (3) and the phosphorus-containing compound, or it may be carried out by mixing the pulverized and/or classified carbide obtained in step (3) and the phosphorus-containing compound.

The phosphorus-containing compound that can be used in step (a) is not particularly limited as long as it has a phosphorus atom in its molecule, but includes, for example, inorganic phosphoric acid, organic phosphoric acid, salts thereof, organic phosphorus, phosphonium salts, etc. can be used. As the phosphorus-containing compound, one type of phosphorus-containing compound may be used, or two or more types may be used in combination.

Examples of inorganic phosphoric acids include phosphoric acid, dihydrogen phosphate, ammonium dihydrogen phosphate, primary phosphate, secondary phosphate, tertiary phosphate, pyrophosphoric acid, pyrophosphate, tripolyphosphoric acid, Examples include tripolyphosphate, phosphorous acid, phosphite, hypophosphorous acid, hypophosphite, diphosphorus pentoxide, and the like. Examples of the organic phosphoric acid include phosphonic acid (phosphonic acid compound), and examples of the phosphonic acid include nitrilotrismethylenephosphonic acid, phosphonobutanetricarboxylic acid, methyldiphosphonic acid, methylenephosphonic acid, ethylidene diphosphonic acid, Examples include triphenyl phosphate. When these phosphoric acids are salts, the salts may be, for example, alkali metal salts and/or alkaline earth metal salts, or ammonium salts. Examples of the organic phosphorus include triphenylphosphine, triphenylphosphine oxide, tricyclohexylphosphine, tricyclohexylphosphine oxide, trialkylphosphine, and trialkylphosphine oxide. Examples of the phosphonium salts include tetraalkylphosphonium salts and tetraphenylphosphonium salts. These salts may be, for example, halides, sulfates, phosphates, or acetates. Among these phosphorus-containing compounds, phosphoric acid and ammonium dihydrogen phosphate, which have a high phosphorus content in the molecule, are preferred from the viewpoint that a large amount of the phosphorus element is easily incorporated into the carbonaceous material. The phosphorus-containing compound is preferably a compound whose volatilization temperature is preferably 100°C or higher, more preferably 150°C or higher, from the viewpoint of reaction with the sugar compound during the heat treatment process.

The method of mixing the phosphorus-containing compound in step (a) is also not particularly limited, and when the phosphorus-containing compound is solid, the solid phosphorus-containing compound and a compound having a saccharide skeleton may be mixed. Further, when the phosphorus-containing compound is water-soluble, for example, an aqueous solution of the phosphorus-containing compound and a compound having a saccharide skeleton may be mixed.

The amount of the phosphorus-containing compound mixed in step (a) is not particularly limited as long as a carbonaceous material having a phosphorus element content in the above range is finally obtained, but for example, a compound having a saccharide skeleton and a nitrogen-containing compound or based on the amount of carbide obtained in step (2), preferably from 0.5 to 10% by mass, more preferably from 0.6 to 8% by mass. Further, the amount of the phosphorus-containing compound mixed in step (a) is preferably 0.001 to 0.20 mol, more preferably The amount is 0.005 to 0.15 mol, more preferably 0.01 to 0.10 mol.

Further, in step (4), a volatile organic substance may be added to the pulverized and/or classified carbide obtained from step (3), and the mixture may be subjected to step (4). When volatile organic substances are heat-treated with an inert gas such as nitrogen (e.g., at 500°C or higher), they do not carbonize (e.g., 80% or more, preferably 90% or more) but volatilize (evaporate or thermally decompose and turn into gas). ) Refers to organic compounds. Examples of volatile organic substances include, but are not limited to, thermoplastic resins and low-molecular organic compounds. Specifically, examples of the thermoplastic resin include polystyrene, polyethylene, polypropylene, poly(meth)acrylic acid, poly(meth)acrylic ester, and the like. Note that in this specification, (meth)acrylic is a general term for methacryl and acrylic. It may also be a resin that partially contains a thermoplastic resin, such as a copolymer, such as acrylonitrile/chlorinated polyethylene/styrene copolymer (ACS resin), acrylonitrile/acrylic acid, etc. Ester/styrene copolymer (AAS resin), acrylonitrile/ethylene/styrene copolymer (AES resin), styrene/ethylene/propylene/styrene block copolymer (SEPS resin), styrene/ethylene/butylene/styrene block copolymer Coalescence (SEBS resin), styrene-isoprene-styrene block copolymer (SIS resin), styrene-butadiene-styrene block copolymer (SBS resin), acrylonitrile-styrene copolymer (AS resin), acrylonitrile-butadiene-styrene Examples include copolymers (ABS resins). Examples of low-molecular organic compounds include ethylene, propane, hexane, toluene, xylene, mesitylene, styrene, naphthalene, phenanthrene, anthracene, pyrene, and the like. The thermoplastic resin is preferably polystyrene, polyethylene, polypropylene, or poly(meth)acrylic acid, since it is preferable to use one that volatilizes at the firing temperature and does not oxidize the surface of the carbon precursor when it is thermally decomposed. The low-molecular-weight organic compound preferably has low volatility at room temperature (for example, 20° C.) from the viewpoint of safety, and naphthalene, phenanthrene, anthracene, pyrene, etc. are preferable. Addition of such a volatile organic substance is preferable in that the hydrogen element content, oxygen element content, and specific surface area can be further reduced while maintaining the characteristic structure of the present invention.

Alternatively, the volatile organic substance may be gasified and mixed with an inert gas such as nitrogen, and then subjected to step (4). Volatile organic substances include, but are not particularly limited to, low-molecular organic compounds. Examples of low-molecular organic compounds include ethylene, propane, hexane, toluene, xylene, mesitylene, styrene, naphthalene, phenanthrene, anthracene, pyrene, and the like. As the low-molecular organic compound, a compound with high volatility is preferable from the viewpoint of miscibility with an inert gas such as nitrogen, and ethylene, propane, hexane, toluene, etc. are preferable. Addition of such a volatile organic substance is preferable in that the hydrogen element content, oxygen element content, and specific surface area can be further reduced while maintaining the characteristic structure of the present invention.

When a volatile organic substance is added in step (4) as described above, it is thought that the volatile organic substance deactivates the radical active sites on the surface of the particles of the carbonaceous material. Such radical active sites usually react with oxygen in the air and increase the oxygen element content of the carbonaceous material. In a preferred embodiment of the present invention, when the oxygen element content of the carbonaceous material is low, it is thought that there are few radical reaction sites on the surface of the carbonaceous material, making it difficult to oxidize, and the reaction sites during repeated charging and discharging. It is thought that this will reduce the number of sites that can cause this. As a result, it is thought that when the radical active sites of the carbonaceous material are deactivated by volatile organic substances, it becomes easier to maintain a higher discharge capacity even after repeated charging and discharging.

Further, after step (4), a step (4') of further heat treatment in the presence of a volatile organic substance can also be performed. When step (4') is performed, it is considered that the radical active sites on the surface of the carbonaceous material particles can be further reduced while maintaining the carbon structure obtained in step (4). The heat treatment temperature in step (4') is less than 1200°C, preferably from 700 to less than 1200°C, more preferably from 750 to 1100°C, even more preferably from 800 to 1000°C. From the viewpoint of easily maintaining the carbon structure obtained in step (4) and obtaining a high discharge capacity, the heat treatment temperature in step (4') is preferably at most the above upper limit. Further, from the viewpoint of sufficiently decomposing the volatile organic matter and easily deactivating the radical active sites of the carbonaceous material, the heat treatment temperature in step (4') is preferably equal to or higher than the above lower limit. The heat treatment time in step (4') is such that the holding time at the final temperature is preferably 1 minute to 1 hour, more preferably 10 minutes to 40 minutes. If the heat treatment temperature and time are within the above range, it is believed that the radical active sites of the carbonaceous material can be further reduced, and as a result, a higher discharge capacity is maintained even after repeated charging and discharging. It is thought that it will be easier to do.

When producing a carbonaceous material by the above production method, in addition to steps (1) to (5), the production method further includes a step of mixing a compound having a sugar skeleton and a nitrogen-containing compound to obtain a mixture. Before (1), simultaneously with step (1), or after step (1), the method may further include a step (b) of gelatinizing the compound having a saccharide skeleton. When step (b) is further performed, the cavities contained in the compound having a saccharide skeleton used as a raw material are closed, and as a result, it is easy to increase the density of the electrode formed from the carbonaceous material finally obtained, and the density per volume is increased. It becomes easier to increase the discharge capacity of

When performing step (b), the gelatinization method is not particularly limited, and the compound having a saccharide skeleton is heated in the presence of water, either alone or in any mixture with a nitrogen-containing compound, etc. methods, and methods in which a compound having a saccharide skeleton is subjected to mechanical treatment with the effects of impact, crushing, friction, and/or shearing, alone or in any mixture with a nitrogen-containing compound, etc. It will be done. By applying such heat and external force, cavities contained in the compound having a sugar skeleton are closed. In the gelatinization in the above step (b), for example, in an image obtained by observing a cross section of a compound having a sugar skeleton after gelatinization using a secondary electron microscope, particles having a cross-sectional area of 3 μm ² or more and 100 μm ² or less When 20 particles are arbitrarily selected, it is preferable to carry out the process until the number of particles having voids of 1 μm ² or more becomes a predetermined amount or less, preferably 3 or less, more preferably 2 or less, still more preferably 1 or less. . The above-mentioned microscopic observation may be performed after the aggregates contained in the gelatinized compound are removed by crushing or classification. When performing step (b), the mixture obtained through step (1) and optional step (b) as described above is heat-treated in step (2). Therefore, when performing step (b), this step (b) is a step performed before step (2).

In a preferred embodiment of the present invention, the manufacturing method of the present invention may include the following steps as step (b):
Before step (1), a step (b1) of mixing a compound having a saccharide skeleton with 5 to 50% by mass of water based on the mass of the compound and heating it at a temperature of 50 to 200°C for 1 minute to 5 hours ),
Before step (1), a step (c1) of subjecting the compound having a saccharide skeleton to a mechanical treatment having the effects of impact, crushing, friction, and/or shearing;
At the same time as step (1) or after step (1), 5 to 50% by mass of water based on the mass of the compound having a saccharide skeleton is mixed with the mixture containing the compound having a saccharide skeleton, and the mixture is heated at 50 to 200°C. Step (b2) of heating at a temperature of 1 minute to 5 hours, and/or
Simultaneously with step (1) or after step (1), a step (c2) of subjecting the mixture containing a compound having a saccharide skeleton to a mechanical treatment having the effects of impact, crushing, friction, and/or shearing.

In step (b1), before step (1), a compound having a saccharide skeleton is mixed with 5 to 50% by mass of water based on the mass of the compound, and the mixture is heated at a temperature of 50 to 200°C for 1 to 5 minutes. This is a process of heating for a period of time. When mixing water with a compound having a sugar skeleton, a certain amount or more of water is required, but in the process of manufacturing carbonaceous materials, the energy required to distill off the mixed water can be suppressed. From a viewpoint, the smaller the better, and the amount is 5 to 50% by weight, preferably 10 to 50% by weight, and more preferably 10 to 30% by weight based on the weight of the compound. Further, the heating temperature is 50 to 200°C, preferably 60 to 180°C, more preferably 80 to 180°C. Further, the heating time is 1 minute to 5 hours, preferably 3 minutes to 1 hour, more preferably 10 minutes to 30 minutes.

Step (c1) is a step in which, prior to step (1), the compound having a sugar skeleton is subjected to mechanical treatment having the effects of impact, crushing, friction, and/or shearing. Devices used in mechanical processing with impact, crushing, friction, and/or shearing effects include, for example, crushers, extruders, flour mills, mills, kneading devices. Although processing conditions such as processing time are not particularly limited, for example, when using a ball vibrating mill, processing conditions of 20 Hz and 10 minutes can be mentioned.

Step (b2) is, simultaneously with step (1) or after step (1), mixing 5 to 50% by mass of water with respect to the mass of the compound having a saccharide skeleton into the mixture containing the compound having a saccharide skeleton. This is a step of heating at a temperature of 50 to 200° C. for 1 minute to 5 hours, and the descriptions of preferred embodiments and the like described regarding step (b1) apply similarly.

In step (c2), simultaneously with step (1) or after step (1), the mixture containing the compound having a saccharide skeleton is subjected to mechanical treatment having the effects of impact, crushing, friction, and/or shearing. This is a step, and the descriptions of preferred embodiments and the like described with respect to step (c1) apply similarly.

The carbonaceous material of the present invention or the carbonaceous material obtained by the manufacturing method of the present invention can be suitably used as an active material of a negative electrode for an electricity storage device.

Below, a method for manufacturing a negative electrode for an electricity storage device using the carbonaceous material of the present invention will be specifically described. For the negative electrode, for example, a binder is added to a carbonaceous material, an appropriate amount of a suitable solvent is added, and then these are kneaded to prepare an electrode mixture. The obtained electrode mixture is applied to a current collector plate made of a metal plate, etc., dried, and then pressure-molded to form a negative electrode for a power storage device, such as a lithium ion secondary battery, a sodium ion battery, a lithium sulfur battery, A negative electrode for non-aqueous electrolyte secondary batteries such as lithium-air batteries can be manufactured.

By using the carbonaceous material of the present invention, an electrode (negative electrode) that has a high discharge capacity per weight, excellent current efficiency, and can maintain high discharge capacity even after repeated charging and discharging is manufactured. be able to. If it is desired to impart higher conductivity to the electrode, a conductive additive can be added, if necessary, during preparation of the electrode mixture. As the conductive aid, conductive carbon black, vapor grown carbon fiber (VGCF), nanotube, etc. can be used. The amount of conductive aid added varies depending on the type of conductive aid used, but if the amount added is too small, the expected conductivity may not be obtained, and if it is too large, dispersion in the electrode mixture may be poor. It may happen. From this point of view, when adding a conductive aid, the amount thereof is preferably 0.5% when the amount of active material (carbonaceous material) + amount of binder + amount of conductive aid = 100% by mass. The amount is 5 to 10% by weight, more preferably 0.5 to 7% by weight, and even more preferably 0.5 to 5% by weight. The binder is not particularly limited as long as it does not react with the electrolyte, but examples include PVDF (polyvinylidene fluoride), polytetrafluoroethylene, and a mixture of SBR (styrene butadiene rubber) and CMC (carboxymethylcellulose). etc. Among them, a mixture of SBR and CMC is preferable because the SBR and CMC attached to the surface of the active material hardly inhibit the movement of lithium ions and good input/output characteristics can be obtained. A polar solvent such as water is preferably used to dissolve an aqueous emulsion such as SBR or CMC to form a slurry, but a solvent emulsion such as PVDF can also be used by dissolving it in N-methylpyrrolidone or the like. If the amount of binder added is too large, the resistance of the resulting electrode will increase, which may increase the internal resistance of the battery and deteriorate the battery characteristics. Furthermore, if the amount of the binder added is too small, the bond between particles of the negative electrode material and with the current collector may become insufficient. The preferred amount of the binder added varies depending on the type of binder used, but for example, in the case of a binder that uses water as a solvent, a mixture of multiple binders such as a mixture of SBR and CMC is often used; The total amount of all binders used is preferably 0.5 to 5% by mass, more preferably 1 to 4% by mass. On the other hand, in the case of a PVDF-based binder, the content is preferably 3 to 13% by mass, more preferably 3 to 10% by mass. Further, the amount of carbonaceous material in the electrode mixture is preferably 80% by mass or more, and more preferably 90% by mass or more. Further, the amount of carbonaceous material in the electrode mixture is preferably 100% by mass or less, more preferably 97% by mass or less.

The carbonaceous material of the present invention has excellent dispersibility when preparing a slurry, and can suppress agglomeration when applying an electrode mixture to a current collector plate made of a metal plate or the like.

The electrode active material layer is basically formed on both sides of the current collector plate, but may be formed on one side if necessary. The thicker the electrode active material layer is, the less current collector plates, separators, etc. are required, which is preferable for increasing capacity. However, since the wider the area of the electrode facing the counter electrode is, the more advantageous it is to improving the input/output characteristics, the input/output characteristics may deteriorate if the electrode active material layer is too thick. The thickness of the active material layer (per side) is preferably 10 to 80 μm, more preferably 20 to 75 μm, and even more preferably 30 to 75 μm, from the viewpoint of output during battery discharge.

The electricity storage device using the carbonaceous material of the present invention has high discharge capacity per weight and excellent current efficiency, and can maintain high discharge capacity even after repeated charging and discharging. When forming a negative electrode for a power storage device using the carbonaceous material of the present invention, the positive electrode material, the separator, and other materials constituting the battery such as the electrolyte are not particularly limited, and are not limited to those conventionally used for power storage devices. Alternatively, it is possible to use various materials that have been proposed.

For example, the positive electrode material may be a layered oxide (expressed as LiMO ₂ , where M is a metal; for example, LiCoO ₂ , LiNiO ₂ , LiMnO ₂ , or _LiNix Co _y Mo _z O ₂ (where x, y , z represents the composition ratio)), olivine type (represented by _LiMPO4 , M is a metal such as _LiFePO4 ), spinel type (represented by _LiM2O4 , M is a metal such as _{LiMn2O4 ,} etc. ₎ ) are preferred, and these chalcogen compounds may be mixed and used if necessary. A positive electrode is formed by molding these positive electrode materials together with a suitable binder and a carbon material for imparting conductivity to the electrode, and forming a layer on a conductive current collector.

For example, when the electricity storage device is a non-aqueous electrolyte secondary battery, a non-aqueous electrolyte solution is generally formed by dissolving an electrolyte in a non-aqueous solvent. Examples of non-aqueous solvents include organic solvents such as propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, dimethoxyethane, diethoxyethane, γ-butyllactone, tetrahydrofuran, 2-methyltetrahydrofuran, sulfolane, or 1,3-dioxolane. These can be used alone or in combination of two or more. Further, as the electrolyte, LiClO ₄ , LiPF ₆ , LiBF ₄ , LiCF ₃ SO ₃ , LiAsF ₆ , LiCl, LiBr, LiB(C ₆ H ₅ ) ₄ , LiN(SO ₃ CF ₃ ) ₂ or the like is used.

In addition, when the electricity storage device is a non-aqueous electrolyte secondary battery, the non-aqueous electrolyte secondary battery generally has a positive electrode and a negative electrode formed as described above facing each other with a liquid-permeable separator interposed therebetween as necessary. It is formed by immersing it in an electrolyte. As such a separator, a permeable or liquid-permeable separator made of nonwoven fabric or other porous material that is commonly used in secondary batteries can be used. Alternatively, a solid electrolyte made of a polymer gel impregnated with an electrolytic solution can also be used instead of or together with the separator.

The carbonaceous material of the present invention is suitable, for example, as a carbonaceous material for an electricity storage device (typically a non-aqueous electrolyte secondary battery for driving a vehicle) mounted on a vehicle such as an automobile. In the present invention, the term "vehicle" refers to a vehicle that is generally known as an electric vehicle, a hybrid vehicle with a fuel cell or an internal combustion engine, etc., without any particular limitation, but at least a power supply device equipped with the above-mentioned battery. The apparatus includes: an electric drive mechanism that is driven by power supplied from the power supply device; and a control device that controls the electric drive mechanism. The vehicle may further include a generating brake or a regenerative brake, and a mechanism for converting energy from braking into electricity and charging the non-aqueous electrolyte secondary battery.

EXAMPLES Hereinafter, the present invention will be specifically explained with reference to Examples, but these are not intended to limit the scope of the present invention. The carbonaceous material and the method for measuring the physical properties of a negative electrode using the same are described below, but the physical properties and measurements (or physical property values and measured values) described in this specification, including the examples, are as follows: It is based on the value obtained by the following method.

(Hydrogen, oxygen and nitrogen element content)
Elemental analysis was performed based on the inert gas dissolution method using an oxygen/nitrogen/hydrogen analyzer EMGA-930 manufactured by Horiba, Ltd.
The detection methods of this device are: oxygen: inert gas melting - non-dispersive infrared absorption method (NDIR), nitrogen: inert gas melting - thermal conduction method (TCD), hydrogen: inert gas melting - non-dispersive infrared absorption method. (NDIR), and calibration was performed using (oxygen/nitrogen) Ni capsules, TiH ₂ (H standard sample), SS-3 (O standard sample), and SiN (N standard sample), and pretreatment at 250°C. 20 mg of the sample whose water content was measured in about 10 minutes was placed in a Ni capsule, degassed for 30 seconds in an elemental analyzer, and then measured. Three samples were analyzed in the test, and the average value was taken as the analytical value. The hydrogen, oxygen, and nitrogen element contents in the sample were obtained as described above.

(phosphorus element content)
Manufactured by Rigaku Co., Ltd. Analysis was performed using ZSX Primus-μ based on fluorescent X-ray analysis.
Using a holder for the top irradiation method, the sample measurement area was set within the circumference of a circle with a diameter of 30 mm. 2.0 g of a sample to be measured and 2.0 g of a polymer binder (Spectro Blend 44μ Powder manufactured by Chemplex) were mixed in a mortar and placed in a molding machine. A load of 15 tons was applied to the molding machine for 1 minute to produce pellets with a diameter of 40 mm. The produced pellets were wrapped in a polypropylene film, placed in a sample holder, and measured. The X-ray source was set at 30 kV and 100 mA. In order to determine the phosphorus element content from the intensity of the phosphorus Kα ray, we used Ge (111) as the spectroscopic crystal and a gas flow type proportional coefficient tube as the detector, and scanned the range of 2θ from 137 to 144 degrees at a scanning speed of 4 degrees/ Measured in minutes.

(Measurement of average interplanar spacing d ₀₀₂ using Bragg equation by X-ray diffraction measurement)
Using "MiniFlex II manufactured by Rigaku Co., Ltd.", a sample holder was filled with carbonaceous material powder prepared in the Examples and Comparative Examples described later, and CuKα rays made monochromatic by a Ni filter were used as a radiation source, and an X-ray diffraction pattern was obtained. I got it. The peak position of the diffraction pattern was determined by the centroid method (a method of determining the centroid position of the diffraction line and calculating the peak position using the corresponding 2θ value), using the diffraction peak of the (111) plane of high-purity silicon powder for standard material. I corrected it. The wavelength λ of the CuKα ray was set to 0.15418 nm, and d ₀₀₂ was calculated using Bragg's formula described below.

(Particle size distribution by laser scattering method)
The average particle diameter (particle size distribution) of the carbide was measured by the following method. 5 mg of the sample was added to 2 mL of an aqueous solution containing 5% by mass of a surfactant ("Toriton Particle size distribution was measured using this dispersion. The particle size distribution measurement was performed using a particle size/particle size distribution measuring device (Microtrac MT3300EXII, manufactured by Microtrac Bell Co., Ltd.). _D50 is the particle diameter at which the cumulative volume is 50%, and this value was used as the average particle diameter.

(Raman spectrum)
Using a Raman spectrometer (Laser Raman Microscope Ramanforce, manufactured by Nanophoton), set the particle to be measured, which is a carbonaceous material, on the observation stage, set the objective lens to 20x magnification, focus, and collect argon ions. Measurements were made while irradiating with laser light. Details of the measurement conditions are as follows. From the obtained Raman spectrum, the half-width of the peak around 1360 cm ⁻¹ and the half-width of the peak around 1650 cm ⁻¹ were determined.
Argon ion laser light wavelength: 532nm
Laser power on sample: 100-300W/ ^cm2
Resolution: 5-7cm ^-1
Measuring range: 150-4000cm ^-1
Measurement mode: XY Averaging
Exposure time: 20 seconds Integration count: 2 Peak intensity measurement: Baseline correction Automatic correction with Polynom-3rd order
Peak search & fitting processing GaussLoren

(Example 1)
100 parts by mass of starch (cornstarch), 11.6 parts by mass of melamine (0.15 mol per mol of starch monosaccharide unit), 7.6 parts by mass of adipic acid (0.08 parts by mass per 1 mol of starch monosaccharide unit) mol), 4 parts by mass of ammonium dihydrogen phosphate (0.06 mol per 1 mol of starch monosaccharide unit) was placed in a sample bottle and mixed to obtain a mixture (Step 1 and Step a). The resulting mixture was heated to 600° C. in a nitrogen gas atmosphere. At this time, the temperature increase rate up to 600°C was 600°C/hour (10°C/min). Next, a carbide was obtained by performing a carbonization treatment by heat treatment at 600° C. for 30 minutes under a nitrogen gas flow (Step 2). At this time, the amount of nitrogen gas supplied was 0.5 L/min per 10 g of starch. Thereafter, the obtained carbide was pulverized using a ball mill to obtain a pulverized carbide having a _D50 of 5.5 μm (Step 3). Next, the crushed carbide and polystyrene (manufactured by Sekisui Plastics Co., Ltd., average particle size 400 μm) were placed in a 100 ml container at a mass ratio of 1:0.1, and the mixture was shaken at 2 Hz for 5 minutes. Mixed. The resulting mixture was heated to 1250°C and subjected to a high-temperature firing process in which it was heat-treated at 1250°C for 30 minutes to obtain a heat-treated product (Step 4). At this time, the temperature increase rate up to 1250°C was 600°C/hour (10°C/min). The above temperature increase and heat treatment were performed under a nitrogen gas stream. The amount of nitrogen gas supplied was 3 L/min per 5 g of pulverized carbide. Subsequently, 1 part by mass of adipic acid was added to 100 parts by mass of the heat-treated product, the mixture was poured into a sample bottle and mixed by shaking, and the temperature was raised to 150° C. in a nitrogen gas atmosphere. At this time, the rate of temperature increase up to 150°C was 600°C/hour (10°C/min). A carbonaceous material was obtained by performing post-heat treatment at 150° C. for 1 hour (Step 5).

(Example 2)
Steps (1) to (5) were carried out in the same manner as in Example 1, except that citric acid was used instead of adipic acid as the additive in step (5), to obtain a carbonaceous material.

(Example 3)
Steps (1) to (5) were carried out in the same manner as in Example 1, except that glucose was used instead of adipic acid as the additive in step (5), to obtain a carbonaceous material.

(Example 4)
Steps (1) to (5) were carried out in the same manner as in Example 1, except that the additive in step (5) was replaced with fructose, and the heat treatment temperature in step (5) was 130°C and the heat treatment time was 3 hours. A carbonaceous material was obtained.

(Comparative example 1)
100 parts by mass of starch (cornstarch), 11.6 parts by mass of melamine (0.15 mol per mol of starch monosaccharide unit), 7.6 parts by mass of adipic acid (0.08 parts by mass per 1 mol of starch monosaccharide unit) mol), 4 parts by mass of ammonium dihydrogen phosphate (0.06 mol per 1 mol of starch monosaccharide unit) was placed in a sample bottle and mixed to obtain a mixture (Step 1 and Step a). The resulting mixture was heated to 600° C. in a nitrogen gas atmosphere. At this time, the temperature increase rate up to 600°C was 600°C/hour (10°C/min). Next, a carbide was obtained by performing a carbonization treatment by performing a heat treatment at 600° C. for 30 minutes under a nitrogen gas flow (Step 2). At this time, the amount of nitrogen gas supplied was 0.5 L/min per 10 g of starch. Thereafter, the obtained carbide was pulverized using a ball mill to obtain a pulverized carbide having a _D50 of 5.5 μm (Step 3). Next, the crushed carbide and polystyrene (manufactured by Sekisui Plastics Co., Ltd., average particle size 400 μm) were placed in a 100 ml container at a mass ratio of 1:0.1, and the mixture was shaken at 2 Hz for 5 minutes. Mixed. A carbonaceous material was obtained by performing a high-temperature firing process in which the resulting mixture was heated to 1250°C and heat-treated at 1250°C for 30 minutes (Step 4). At this time, the temperature increase rate up to 1250°C was 600°C/hour (10°C/min). The above temperature increase and heat treatment were performed under a nitrogen gas stream. The amount of nitrogen gas supplied was 3 L/min per 5 g of pulverized carbide.

(Comparative example 2)
100 parts by mass of starch (corn starch), 5.4 parts by mass of melamine (0.07 mol per mol of starch monosaccharide unit), 3.8 parts by mass of adipic acid (0.04 parts by mass per 1 mol of starch monosaccharide unit) mol), 2 parts by mass of ammonium dihydrogen phosphate (0.03 mol per mol of starch monosaccharide unit) was placed in a sample bottle and shaken to obtain a mixture (Step 1 and Step a). The resulting mixture was heated to 600° C. in a nitrogen gas atmosphere. At this time, the temperature increase rate up to 600°C was 600°C/hour (10°C/min). Next, a carbide was obtained by performing a carbonization treatment by heat treatment at 600° C. for 30 minutes under a nitrogen gas flow (Step 2). At this time, the amount of nitrogen gas supplied was 0.5 L/min per 10 g of starch. Thereafter, the obtained carbide was pulverized with a ball mill to obtain a pulverized carbide having a _D50 of 5.5 μm (Step 3). The resulting pulverized carbide was heated to 1150°C and subjected to a high-temperature firing process in which it was heat-treated at 1150°C for 60 minutes to obtain a carbonaceous material (Step 4). At this time, the temperature increase rate up to 1150°C was 600°C/hour (10°C/min). The above temperature increase and heat treatment were performed under a nitrogen gas stream. The amount of nitrogen gas supplied was 3 L/min per 5 g of pulverized carbide.

(Comparative example 3)
100 parts by mass of starch (cornstarch), 11.6 parts by mass of melamine (0.15 mol per mol of starch monosaccharide unit), 7.6 parts by mass of adipic acid (0.08 parts by mass per 1 mol of starch monosaccharide unit) mol), 4 parts by mass of ammonium dihydrogen phosphate (0.06 mol per 1 mol of starch monosaccharide unit) was placed in a sample bottle and mixed to obtain a mixture (Step 1 and Step a). The resulting mixture was heated to 600° C. in a nitrogen gas atmosphere. At this time, the temperature increase rate up to 600°C was 600°C/hour (10°C/min). Next, a carbide was obtained by performing a carbonization treatment by performing a heat treatment at 600° C. for 30 minutes under a nitrogen gas flow (Step 2). At this time, the amount of nitrogen gas supplied was 0.5 L/min per 10 g of starch. Thereafter, the obtained carbide was pulverized with a ball mill to obtain a pulverized carbide having a _D50 of 5.5 μm (Step 3). The resulting pulverized carbide was heated to 1100° C. and subjected to a high-temperature firing process (step 4) in which it was heat-treated at 1100° C. for 60 minutes to obtain a carbonaceous material. At this time, the rate of temperature increase up to 1100°C was 600°C/hour (10°C/min). The above temperature increase and heat treatment were performed under a nitrogen gas stream. The amount of nitrogen gas supplied was 3 L/min per 5 g of pulverized carbide.

(Comparative example 4)
100 parts by mass of starch (cornstarch), 2 parts by mass of melamine (0.026 mol per mol of starch monosaccharide unit), 7.6 parts by mass of adipic acid (0.08 mol per mol of starch monosaccharide unit) , 4 parts by mass of ammonium dihydrogen phosphate (0.06 mol per mol of starch monosaccharide unit) was placed in a sample bottle and shaken to obtain a mixture (Step 1 and Step a). The resulting mixture was heated to 600° C. in a nitrogen gas atmosphere. At this time, the temperature increase rate up to 600°C was 600°C/hour (10°C/min). Next, a carbide was obtained by performing a carbonization treatment by performing a heat treatment at 600° C. for 30 minutes under a nitrogen gas flow (Step 2). At this time, the amount of nitrogen gas supplied was 0.5 L/min per 10 g of starch. Thereafter, the obtained carbide was pulverized with a ball mill to obtain a pulverized carbide having a _D50 of 5.5 μm (Step 3). The resulting pulverized carbide was heated to 1200° C. and subjected to a high-temperature firing process in which it was heat-treated at 1200° C. for 60 minutes to obtain a carbonaceous material (Step 4). At this time, the temperature increase rate up to 1200°C was 600°C/hour (10°C/min). The above temperature increase and heat treatment were performed under a nitrogen gas stream. The amount of nitrogen gas supplied was 3 L/min per 5 g of pulverized carbide.

(Preparation of electrode)
Using the carbonaceous materials obtained in each example and comparative example, a negative electrode was produced according to the following procedure.
95 parts by mass of carbonaceous material, 2 parts by mass of conductive carbon black ("Super-P (registered trademark)" manufactured by TIMCAL), 1 part by mass of carboxymethyl cellulose (CMC), 2 parts by mass of styrene-butadiene rubber (SBR), and water. 90 parts by mass were mixed to obtain a slurry. The obtained slurry was applied to a 15 μm thick copper foil, dried and then pressed to obtain a punched electrode with a diameter of 14 mm and a thickness of 45 μm.

(discharge capacity and current efficiency per weight)
The electrode produced above was used as a working electrode, and metallic lithium was used as a counter electrode and a reference electrode. As a solvent, ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate were mixed and used in a volume ratio of 1:1:1. 1 mol/L of LiPF ₆ was dissolved in this solvent and used as an electrolyte. A polypropylene membrane was used as the separator. A coin cell was fabricated in a glove box under an argon atmosphere.
A charge/discharge test was conducted on the lithium secondary battery having the above configuration using a charge/discharge test device (manufactured by Toyo System Co., Ltd., "TOSCAT"). Lithium doping was performed at a rate of 70 mA/g relative to the mass of the active material, and doping was performed until the lithium potential became 1 mV. Furthermore, a constant voltage of 1 mV was applied to the lithium potential, and doping was completed when the rate reached 2 mA/g relative to the mass of the active material. The capacity at this time was defined as the charging capacity. Next, dedoping is performed at a rate of 70 mA/g relative to the mass of the active material until the lithium potential becomes 1.5 V, and the charged capacity at this time is called the initial charge capacity (mAh), and the discharged capacity is called the initial discharge capacity. (mAh). The obtained initial charge capacity and initial discharge capacity were each divided by the weight of the negative electrode, and the obtained values were defined as the charge capacity per weight (mAh/g) and the discharge capacity per weight (mAh/g). initial charge/discharge evaluation). Further, the initial discharge capacity was divided by the initial charge capacity, and the percentage of the obtained value was defined as current efficiency (%).

(Capacity retention rate and total efficiency after repeated charging and discharging)
<Capacity retention rate after repeated charging and discharging>
The discharge capacity obtained after repeating the above initial charge/discharge evaluation conditions 10 times was defined as the discharge capacity after repeated charge/discharge. In addition, the capacity retention rate after repeated charging and discharging was calculated using the following formula.
Capacity retention rate after repeated charging and discharging (%) = Discharge capacity after repeated charging and discharging (mAh/g)/Initial discharge capacity (mAh/g) x 100

<Total efficiency after repeated charging and discharging>
The total efficiency after repeated charging and discharging was calculated using the following formula. The total efficiency is an index that indicates both the deterioration due to the first charge/discharge and the deterioration due to repeated charge/discharge.
Total efficiency (%) = Capacity retention rate after repeated charging and discharging (%) x Current efficiency (%) / 100

(Coatability evaluation)
95 parts by mass of carbonaceous material, 2 parts by mass of conductive carbon black ("Super-P (registered trademark)" manufactured by TIMCAL), 1 part by mass of carboxymethyl cellulose (CMC), 2 parts by mass of styrene-butadiene rubber (SBR), and water. 90 parts by mass were mixed to obtain a slurry. The obtained slurry was applied to an area of 10 cm x 10 cm on five copper foils each having a thickness of 15 μm using a doctor blade, and dried at 80° C. for 30 minutes. When the number of spots (average of 5 sheets) confirmed by visual observation of the obtained coating film was 0 to 1, it was rated ◎, when it was 2 to 5, it was rated, and when it was 6 or more, it was rated △. .

Regarding the carbonaceous materials obtained in Examples and Comparative Examples, nitrogen element content, hydrogen element content, oxygen element content (elemental analysis), phosphorus element content, and carbon spacing (d ₀₀₂ ) were determined according to the above measurement method. , the half-width of the peak around 1360 cm ⁻¹ and the half-width of the peak around 1650 cm ⁻¹ are shown in Tables 1 and 2. Furthermore, Table 2 also shows the discharge capacity and current efficiency per weight, the capacity retention rate and total efficiency after repeated charging and discharging, and the coating property evaluation, which were measured for the obtained battery.

The batteries produced using the carbonaceous materials of each example not only had a high discharge capacity per weight and exhibited excellent current efficiency, but also had excellent coatability of the carbonaceous material. Further, even after repeated charging and discharging 10 times, the discharge capacity was high, and the capacity retention rate and overall efficiency were also high. On the other hand, batteries fabricated using the carbonaceous materials of each comparative example that do not meet the specified nitrogen element content, hydrogen element content, and/or phosphorus element content have lower discharge capacity and current efficiency per weight. The results were either not sufficiently high, or the total efficiency was low, or there was room for improvement in coatability.

Claims (7)

According to elemental analysis, the nitrogen element content is 1.0 mass% or more, the oxygen element content is 0.60 mass% or more and 2.0 mass% or less, and the hydrogen element content is 0.1 mass% or less. A carbonaceous material having a phosphorus element content of 0.1% by mass or more and 2.0% by mass or less as determined by X-ray fluorescence analysis. The carbonaceous material according to claim 1, having a carbon plane spacing (d ₀₀₂ ) of 3.65 Å or more as measured by X-ray diffraction. The carbonaceous material according to claim 1, wherein in a Raman spectrum observed by laser Raman spectroscopy, the half-width value of a peak near 1360 cm ^-1 is 210 cm ^-1 or more. The carbonaceous material according to claim 1, which is a carbonaceous material for a negative electrode of an electricity storage device. A negative electrode for a power storage device, comprising the carbonaceous material according to any one of claims 1 to 4. An electricity storage device comprising the negative electrode for an electricity storage device according to claim 5. The following steps:
(1) A step of mixing a compound having a sugar skeleton and a nitrogen-containing compound to obtain a mixture;
(2) heat-treating the mixture at 500 to 900°C under an inert gas atmosphere to obtain a carbide;
(3) a step of pulverizing and/or classifying the carbide; (4) a step of heat-treating the pulverized and/or classified carbide at 1100 to 1600°C in an inert gas atmosphere; At least a step of mixing a carboxylic acid compound or a compound having a saccharide skeleton and heat-treating the mixture at 100°C to 300°C to obtain a carbonaceous material,
(a) Prior to the heat treatment in step (4), the step includes a step of mixing a compound having a sugar skeleton, a mixture containing the compound, or a carbonized product of the mixture, and a phosphorus-containing compound. 4. The method for producing a carbonaceous material according to any one of 4.