WO2025142600A1 - Molybdenum-containing carbonaceous material, negative electrode for power storage device, and power storage device - Google Patents

Abstract

The present invention relates to a carbonaceous material for which the value of the half-value width of the peak in the vicinity of 1360 cm^-1 in the Raman spectrum observed by laser Raman spectroscopy is 200-280 cm^-1, and for which the molybdenum element content as determined by ICP emission spectroscopy is 0.5-7.5 mass%.

Description

Molybdenum-containing carbonaceous material, negative electrode for power storage device, and power storage device

The present invention relates to a carbonaceous material having a specific molybdenum element content, a negative electrode for an electricity storage device that includes the carbonaceous material, and an electricity storage device that includes the negative electrode for an electricity storage device.

Electricity storage devices are devices such as secondary batteries and capacitors that utilize electrochemical phenomena, and are in widespread use. For example, lithium-ion secondary batteries, which are one type of electricity storage device, are widely used in small portable devices such as mobile phones and laptops.

For example, in Patent Document 1, a carbonaceous material is proposed as a negative electrode material for non-aqueous electrolyte secondary batteries such as lithium ion secondary batteries, in which the nitrogen element content is 1.0 mass% or more, the oxygen content is 1.5 mass% or less, the ratio of the nitrogen element content to the hydrogen element content (R _{N / H} ) is 6 to 100, the ratio of the oxygen content to the nitrogen content (R _{O / N} ) is 0.1 to 1.0, and the carbon interplanar spacing (d ₀₀₂ ) observed by X-ray diffraction measurement is 3.70 Å or more, and it is described that this carbonaceous material is suitable as a negative electrode active material for non-aqueous electrolyte secondary batteries having high charge/discharge capacity, preferably high charge/discharge efficiency, and low resistance. The same document also describes that it is preferable that the half-width value of the peak near 1360 cm ^-1 in the Raman spectrum observed by laser Raman spectroscopy of the carbonaceous material is preferably 190 cm ^-1 or more, because there tends to be more sites for lithium ions to be absorbed.

International Publication No. 2019/009333

However, there is a continuing need to develop carbonaceous materials that can result in electricity storage devices with superior electrical properties.
An object of the present invention is to provide a carbonaceous material that, when applied to a negative electrode, can provide an electricity storage device having high charge capacity and discharge capacity per mass, high current efficiency, and high energy density. Another object of the present invention is to provide an electricity storage device negative electrode containing such a carbonaceous material, and an electricity storage device containing such an electricity storage device negative electrode.

As a result of extensive investigations, the present inventors have found that the above-mentioned problems can be solved by providing a carbonaceous material having a specific half-width of a Raman spectrum peak and a specific molybdenum content.
That is, the present invention includes the following preferred embodiments.
[1] A carbonaceous material having a half-width value of a peak near 1360 cm ⁻¹ in a Raman spectrum observed by laser Raman spectroscopy of 200 to 280 cm ⁻¹ , and a molybdenum content of 0.5 to 7.5 mass % determined by ICP emission spectrometry.
[2] The carbonaceous material according to [1], wherein the nitrogen element content determined by elemental analysis is 0.5 to 4.6 mass%.
[3] The carbonaceous material according to [1] or [2], which has a BET specific surface area of 3 to 60 m ² /g calculated by the BET method based on a nitrogen adsorption/desorption isotherm obtained by a nitrogen adsorption method.
[4] The following formula (1):
Molybdenum modification rate (mass %/(m ² /g))=molybdenum element content (mass %)/BET specific surface area (m ² /g) Formula (1)
The carbonaceous material according to any one of [1] to [3], wherein the molybdenum modification rate calculated by the above formula is 0.10 to 1.08 mass %/(m ² /g).
[5] The carbonaceous material according to any one of [1] to [4], wherein the carbon interplanar spacing (d ₀₀₂ ) determined by X-ray diffraction measurement is 3.65 to 4.00 Å.
[6] The carbonaceous material according to any one of [1] to [5], wherein the true density of the carbonaceous material determined by a helium method is 1.30 to 2.10 g/cc.
[7] The carbonaceous material according to any one of [1] to [6], which is a carbonaceous material for a negative electrode of an electricity storage device.
[8] A negative electrode for an electricity storage device, comprising the carbonaceous material according to [7].
[9] An electricity storage device comprising the electricity storage device negative electrode according to [8].

The present invention provides a carbonaceous material that, when applied to a negative electrode, can provide an electricity storage device that has high charge capacity and discharge capacity per mass, high current efficiency, and high energy density.

FIG. 4 is a diagram illustrating the relationship between the discharge capacity and the voltage when the electricity storage device is discharged.

The following describes in detail the embodiments of the present invention. Note that there is no intention to limit the present invention to the following embodiments.

In this specification, the term "electricity storage device" refers to a general device that includes a negative electrode containing a carbonaceous material and utilizes an electrochemical phenomenon. Specifically, the electricity storage device includes, for example, secondary batteries such as lithium ion secondary batteries, nickel hydrogen secondary batteries, and nickel cadmium secondary batteries that can be used repeatedly by charging, and capacitors such as electric double layer capacitors. Of these, the electricity storage device may be a secondary battery, particularly a non-aqueous electrolyte secondary battery (for example, a lithium ion secondary battery, a sodium ion battery, a lithium sulfur battery, a lithium air battery, an all-solid-state battery, an organic radical battery, etc.), and in particular, may be a lithium ion secondary battery.

<Carbonaceous material>
The carbonaceous material of the present invention is characterized in that the half-width value of the peak near 1360 cm ⁻¹ in the Raman spectrum observed by laser Raman spectroscopy is 200 to 280 cm ⁻¹ and the molybdenum content determined by ICP emission spectroscopy is 0.5 to 7.5 mass%. The inventors have found that, because the carbonaceous material has this characteristic, when the carbonaceous material is used as a carbonaceous material for the negative electrode of an electricity storage device, it is possible to achieve a high energy density in addition to a high charge capacity, a high discharge capacity, and a high current efficiency. Although the reason for this is unclear, the following mechanism of action is presumed as a non-limiting mechanism of action.

A large amount of electricity (i.e., energy density) is required to be extracted from an electricity storage device. Usually, the higher the energy density of an electricity storage device, the larger the discharge capacity of the electricity storage device tends to be. However, as can be understood from the relationship between the discharge capacity and the voltage during discharge of an electricity storage device (FIG. 1), even if the discharge capacity is the same, the larger the CV (Constant Voltage) discharge capacity, the larger the energy density. A more detailed explanation will be given using FIG. 1. In order to make the drawing easier to see, the scale ratio of the vertical axis and the horizontal axis in FIG. 1 is appropriately changed.
The left diagram of FIG. 1 shows the relationship between discharge capacity and voltage when a certain storage device is subjected to CC (Constant Current) discharge. The capacity below 0.1V is the CV discharge capacity (shown by a solid line), and the capacity above 0.1V is the CC discharge capacity (shown by a dashed line). To facilitate understanding, in the left diagram of FIG. 1, the CV discharge capacity is set to 250 mAh/g, and the CC discharge capacity is set to 290 mAh/g (=540-250). The discharge capacity of this storage device is 540 mAh/g, which is the sum of the CV discharge capacity and the CC discharge capacity. The energy density of this storage device corresponds to the area S ₁ of the shaded portion. Similarly, the right diagram of FIG. 1 shows the relationship between discharge capacity and voltage when another storage device is subjected to CC discharge. To facilitate understanding, the CV discharge capacity of this electricity storage device was set to 300 mAh/g, and the discharge capacity was set to 540 mAh/g, the same as that of the electricity storage device in the left diagram of Fig. 1. The energy density of this electricity storage device corresponds to the sum of the areas _S1 and _S2 of the shaded areas, and therefore the energy density of the electricity storage device in the right diagram of Fig. ₁ is greater by the amount of S2. In other words, even if the discharge capacity is the same (540 mAh/g), the energy density is greater when the CV discharge capacity is greater.
In addition, when the CV discharge capacity is divided by the CC discharge capacity to obtain a value that is taken as the CV/CC ratio, the larger this value, the higher the energy density tends to be achieved. A higher energy density also tends to be achieved by increasing the charge/discharge efficiency of the negative electrode when preparing an actual battery having a certain capacity. The increase in the charge/discharge efficiency of the negative electrode can be achieved, for example, by reducing the volume (coating amount) of the negative electrode. A higher energy density can also be achieved by increasing the value obtained by multiplying the charge/discharge efficiency by the CV/CC ratio. This is because when the value is high, both the charge/discharge efficiency and the voltage during discharge tend to have favorable values.
When the carbonaceous material is used as a carbonaceous material for the negative electrode of a lithium ion secondary battery, it is considered that, from the structure of the carbonaceous material, the CC discharge capacity is mainly related to the release of lithium ions captured between the carbon surfaces of the carbonaceous material, while the CV discharge capacity is mainly related to the release of lithium ion clusters occluded in the carbonaceous material. The fact that the carbonaceous material of the present invention has a specific half-width value is related to the fact that the spacing of the carbon surfaces of the carbonaceous material is disordered, and as a result, it is considered that more lithium ions can be released because lithium ions are easily captured between the carbon surfaces of the carbonaceous material, that is, high charge/discharge capacity and high CC discharge capacity can be achieved. The carbonaceous material of the present invention also has a molybdenum element content of a specific value or more, but it is considered that clusters of lithium ions are easily formed around this molybdenum element, and as a result, more lithium ions are occluded in the carbonaceous material, and more lithium ions can be released, that is, high charge/discharge capacity, high CV discharge capacity, high current efficiency and high energy density can be achieved.

When the half-width value of the carbonaceous material in the present invention is smaller than 200 cm ^-1 , the carbon structure has fewer disturbances and defects, and the number of storage sites for electrolyte ions (lithium ions in the case of lithium ion secondary batteries) is reduced, so that it tends to be difficult to achieve a high charge/discharge capacity and a high CC discharge capacity of an electrode made using the carbonaceous material. When the half-width value is greater than 280 cm ^-1 , the number of sites for irreversibly storing electrolyte ions in the carbon structure increases, so that it tends to be difficult to achieve a high charge/discharge efficiency. The half-width value is 200 to 280 cm ^-1 , preferably 205 to 280 cm ^-1 , more preferably 210 to 280 cm ^-1 , even more preferably 220 to 280 cm ^-1 , particularly preferably 230 to 275 cm ^-1 , and even more particularly preferably 240 to 270 cm ^-1 . When the half width is equal to or greater than the lower limit, a higher charge/discharge capacity and a higher CC discharge capacity can be achieved for an electrode made using a carbonaceous material. When the half width is equal to or less than the upper limit, a suitable charge/discharge efficiency can be achieved in an electric storage device including an electrode made using a carbonaceous material. Here, the peak near 1360 cm ⁻¹ is a Raman peak generally called a D band, which is a peak caused by disorder/defects in the graphite structure. The peak near 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 the Examples, for example. The value of the half width can be adjusted within the range, for example, by adjusting the amount of the nitrogen-containing compound and the molybdenum-containing compound used in producing the carbonaceous material, and/or by adjusting the temperature or time of the heat treatment.

If the molybdenum content in the carbonaceous material is less than 0.5% by mass, the formation of electrolyte ion clusters may be reduced, and the graphite structure of the carbonaceous material may be insufficiently disordered, making it difficult to achieve the combined characteristics of high charge/discharge capacity, high CV discharge capacity, high current efficiency, and high energy density (particularly high CV discharge capacity) of an electrode made using the carbonaceous material. On the other hand, if the molybdenum content exceeds 7.5% by mass, the graphite structure of the carbonaceous material may be too disordered, resulting in a deterioration of battery characteristics. The molybdenum content is 0.5 to 7.5% by mass, preferably 0.75 to 7.4% by mass, more preferably 1.0 to 7.0% by mass, even more preferably 1.25 to 6.5% by mass, even more preferably 1.50 to 6.0% by mass, and particularly preferably 2.0 to 5.0% by mass. When the molybdenum content is equal to or greater than the lower limit, the combined characteristics of the electrode produced using the carbonaceous material can be improved, and when the molybdenum content is equal to or less than the upper limit, the graphite structure can be appropriately disordered. The molybdenum content is measured by ICP emission spectroscopy under conditions described in the examples. The molybdenum content can be adjusted to within the above range, for example, by adjusting the amount of the molybdenum-containing compound used in producing the carbonaceous material and/or by adjusting the temperature or time of the heat treatment.

From the viewpoint of discharge capacity and current efficiency, the nitrogen element content by elemental analysis of the carbonaceous material is preferably 0.5 to 4.6 mass%, preferably 0.6 to 4.5 mass%, more preferably 0.65 to 4.4 mass%, even more preferably 0.7 to 4.3 mass%, even more preferably 0.8 to 4.2 mass%, particularly preferably 0.9 to 4.0 mass%, more particularly preferably 1.0 to 3.5 mass%, and even more particularly preferably 1.0 to 3.0 mass%. If the nitrogen element content is equal to or greater than the lower limit, the spacing of the carbon surfaces of the carbonaceous material is disturbed, and sites for adsorbing and desorbing electrolyte ions during charging and discharging can be secured, and a higher charge and discharge capacity can be achieved for an electrode made using the carbonaceous material. On the other hand, if the nitrogen element content is equal to or less than the upper limit, the decrease in discharge capacity during repeated charging and discharging can be suppressed, and improved current efficiency can be obtained. The nitrogen element content is an analytical value obtained by elemental analysis of the carbonaceous material, and can be measured, for example, by the method described in the Examples below. The nitrogen element content can be adjusted within the above range, for example, by adjusting the amount of the nitrogen-containing compound or molybdenum-containing compound used in producing the carbonaceous material and/or by adjusting the temperature or time of the heat treatment.

The oxygen element content of the carbonaceous material by elemental analysis is preferably 3.0 mass% or less from the viewpoint of current efficiency, particularly from the viewpoint of suppressing the decrease in discharge capacity and improving current efficiency when charging and discharging are repeated, while the smaller the better, the lower limit is 0 mass% or more. The oxygen element content is more preferably 0 to 3.0 mass%, even more preferably 0 to 2.5 mass%, even more preferably 0 to 2.4 mass%, particularly preferably 0 to 2.3 mass%, even more particularly preferably 0 to 2.2 mass%, and even more particularly preferably 0 to 2.1 mass%. The oxygen element content by elemental analysis represents the amount of oxygen element contained in the entire carbonaceous material. If the oxygen element content by elemental analysis is low, there will be fewer sites that newly react with the electrolyte, electrolyte, or electrolyte ions when charging and discharging are repeated, and the decrease in discharge capacity when charging and discharging is repeated in particular can be suppressed. The oxygen element content by elemental analysis of the carbonaceous material can be reduced by increasing the amount of the nitrogen-containing compound used in producing the carbonaceous material, and can also be adjusted to be below the upper limit value or within the above range by adjusting the temperature or time of heat treatment, etc.

The BET specific surface area of the carbonaceous material calculated by the BET method based on the nitrogen adsorption/desorption isotherm obtained by the nitrogen adsorption method is preferably 3 to 60 ^{m 2} /g (e.g., 3.5 to 60 m ² /g, 4 to 60 ^{m 2} /g, 4.5 to 60 ^{m 2} /g, 5 to 60 m ² /g), more preferably 3 to 40 m ² /g, more preferably 3 to 30 m ² /g, even more preferably 3 to 25 m ² /g, particularly preferably 3 to 15 m ² /g, and more particularly preferably 3 to 10 m ² /g. When the BET specific surface area is within the above range, the thermal contraction of the carbonaceous material can be appropriately controlled, and pores suitable for occlusion of lithium can be formed. Therefore, the capacity of the pores that can be reversibly doped with lithium can be increased. It is also advantageous in that side reactions with the electrolyte are less likely to occur. That is, by controlling the BET specific surface area within the above range, it is possible to increase the charge/discharge capacity and current efficiency, and also to achieve a high energy density. The BET specific surface area can be adjusted within the above range by adjusting the treatment time for crushing and/or classifying the carbide and/or adjusting the temperature or time for the heat treatment when producing the carbonaceous material. The BET specific surface area can be measured using a gas adsorption apparatus, and can be determined, for example, by the method described in the Examples below.

The carbonaceous material has the formula (1):
Molybdenum modification rate (mass %/(m ² /g))=molybdenum element content (mass %)/BET specific surface area (m ² /g) Formula (1)
The molybdenum modification rate calculated by is preferably 0.10 to 1.08 mass%/(m ² /g), more preferably 0.10 to 1.00 mass%/(m ² /g), even more preferably 0.10 to 0.80 mass%/(m ² /g), particularly preferably 0.20 to 0.60 mass%/(m ² /g), and more particularly preferably 0.20 to 0.50 mass%/(m ² /g). When the molybdenum modification rate is within the above range, the molybdenum element is present at a suitable ratio relative to a certain specific surface area, so that side reactions on the electrode surface can be suppressed, and lithium ion clusters can be effectively formed by the molybdenum present on the electrode surface. As a result, the value obtained by multiplying the charge/discharge efficiency by the CV/CC ratio becomes high, and the power storage device can have a high energy density.

The carbon interplanar spacing (d ₀₀₂ ) determined by X-ray diffraction measurement of the carbonaceous material is preferably 3.65 to 4.00 Å, more preferably 3.68 to 3.95 Å, even more preferably 3.70 to 3.90 Å, particularly preferably 3.71 to 3.85 Å, and more particularly preferably 3.73 to 3.85 Å. When the carbon interplanar spacing (d ₀₀₂ ) is equal to or greater than the lower limit, the spacing between the carbon planes widens, and accordingly, the electrolyte ions can move efficiently. In addition, the micropores are sufficiently developed, and accordingly, the number of storage sites for the clustered electrolyte ions can be increased, and as a result, a higher discharge capacity and a higher current efficiency can be obtained. On the other hand, when the carbon interplanar spacing (d ₀₀₂ ) is equal to or less than the upper limit, the volume of the carbonaceous material can be appropriately reduced to increase the effective capacity per volume, and the discharge capacity per volume can be increased. The carbon interplanar spacing (d ₀₀₂ ) is measured using the Bragg equation by X-ray diffraction measurement, specifically, by the method described in the Examples. The carbon interplanar spacing (d ₀₀₂ ) can be adjusted to within the above range, for example, by adjusting the amount of nitrogen-containing compound used in producing the carbonaceous material and/or by adjusting the temperature or time of heat treatment.

The true density of the carbonaceous material in the present invention determined by the helium method (hereinafter sometimes referred to as "true density ρ _He ") is usually 1.30 g/cc or more, preferably 1.30 to 2.10 g/cc, more preferably 1.30 to 2.05 g/cc, even more preferably 1.35 to 2.00 g/cc, still more preferably 1.40 to 1.95 g/cc, particularly preferably 1.45 to 1.90 g/cc, even more particularly preferably 1.50 to 1.85 g/cc, and even more particularly preferably 1.55 to 1.80 g/cc. A small true density ρ _He means that there are many pores into which helium cannot enter. It is believed that when there are many such pores, there are many intercrystalline gaps in the hard carbon, and electrolyte ions are occluded in the intercrystalline gaps in the form of clusters. As a result, more electrolyte ions are occluded in the carbonaceous material, and therefore more electrolyte ions can be released; in other words, it is believed that higher charge/discharge capacity, CV discharge capacity, current efficiency, and energy density can be achieved.
The true density ρ _He can be measured by a gas pycnometer method, for example, by the method described in the Examples below. The true density ρ _He can be adjusted to within the above range, for example, by adjusting the amount of the nitrogen-containing compound used in producing the carbonaceous material and/or by adjusting the temperature or time of the heat treatment.

<Method of producing carbonaceous material>
The method for producing the carbonaceous material of the present invention is not particularly limited as long as a carbonaceous material having the above-mentioned characteristics can be obtained. For example, a method in which a compound serving as a carbon source and a nitrogen-containing compound are mixed, or a nitrogen-containing compound serving as a carbon source is prepared, the resulting mixture or the prepared nitrogen-containing compound is heat-treated under an inert gas atmosphere at 500 to 900 ° C., and then crushed and/or classified, and the resulting crushed and/or classified carbide is further heat-treated at 800 to 1300 ° C., and includes a mixing step with a molybdenum-containing compound before the heat treatment at 800 to 1300 ° C. Here, the above-mentioned "nitrogen-containing compound serving as a carbon source" is different from the "compound (nitrogen-containing compound) other than sugars containing nitrogen" described later. The carbon source compound or nitrogen-containing compound used as the raw material is not particularly limited as long as a carbonaceous material satisfying the above characteristics can be obtained, but from the viewpoint of adjusting the above characteristics of the carbonaceous material to a preferred range, it is preferably a compound having a saccharide skeleton (hereinafter sometimes abbreviated as "saccharide compound". Furthermore, throughout this specification, saccharide compounds include nitrogen-free saccharide compounds and nitrogen-containing saccharide compounds described below) or a nitrogen-containing compound having a saccharide skeleton (hereinafter sometimes abbreviated as "nitrogen-containing saccharide compound"). Therefore, the carbonaceous material of the present invention is preferably a carbonaceous material derived from sugar or nitrogen-containing sugar. Below, a production method using a saccharide compound or a nitrogen-containing saccharide compound as a carbon source will be described.

In a preferred embodiment, the method for producing a carbonaceous material of the present invention includes the following steps (1) to (4):
(1) A step of mixing a nitrogen-free saccharide compound (hereinafter also referred to as a "nitrogen-free saccharide compound") with a nitrogen-containing saccharide compound, or a step of mixing a nitrogen-free saccharide compound and/or a nitrogen-containing saccharide compound with a nitrogen-containing compound other than a saccharide (referred to as a "nitrogen-containing compound" throughout this specification), or a step of preparing a nitrogen-containing saccharide compound;
(2) heat-treating the mixture obtained in step (1) or the nitrogen-containing saccharide compound prepared in step (1) at 500 to 900° C. in an inert gas atmosphere to obtain a carbonized product;
(3) a step of pulverizing and/or classifying the carbide, and (4) a step of heat-treating the pulverized and/or classified carbide at 800 to 1300° C. in an inert gas atmosphere to obtain a carbonaceous material, comprising the following step (a):
(a) including the step of also mixing a molybdenum-containing compound prior to the heat treatment in step (4).

Examples of nitrogen-free sugar compounds that can be used in step (1) include, but are not limited to, monosaccharides such as glucose, galactose, mannose, fructose, and ribose; disaccharides such as sucrose, trehalose, maltose, cellobiose, maltitol, lactobionic acid, and lactosamine; and polysaccharides such as starch, glycogen, agarose, pectin, cellulose, oligosaccharides, and xylitol. As the nitrogen-free sugar compound, one of these compounds may be used, or two or more of them may be used in combination. Among these nitrogen-free sugar compounds, starch is preferred because it is easy to obtain in large quantities. Examples of 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 chestnut starch. These starches may be physically, enzymatically, or chemically processed, and may be starches processed into pregelatinized starch, phosphate crosslinked starch, starch acetate, hydroxypropyl starch, oxidized starch, dextrin, etc. Corn starch and wheat starch, as well as pregelatinized starches thereof, are preferred as starches because of their availability and low cost.

Examples of nitrogen-containing saccharide compounds that can be used in step (1) include, but are not limited to, glucosamine, chitin, chitosan, and quaternary nitrogen-modified polysaccharides (cationically modified hydroxyethylcellulose, cationically modified starch, cationically modified tamarind gum, cationically modified locust bean gum, cationically modified tara gum, cationically modified fenugreek gum, etc.). As the nitrogen-containing saccharide compound, one of these compounds may be used, or two or more of them may be used in combination.
In this specification, a saccharide compound not containing nitrogen or a nitrogen-free saccharide compound means a saccharide compound having a nitrogen element content of less than 500 ppm, and a saccharide compound containing nitrogen or a nitrogen-containing saccharide compound means a saccharide compound having a nitrogen element content of 500 ppm or more.

In a preferred embodiment, from the viewpoint of increasing the density of an electrode obtained from a carbonaceous material, it is preferable to use a saccharide compound in which, when 20 particles having a cross-sectional area of 3 μm ² or more and 100 μm ² or less are arbitrarily selected in an image obtained by observing the cross section of a particle of the compound with a secondary electron microscope, 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 1 or less. When producing a carbide using such a compound with few voids as a raw material, additional processing such as the step (b) described below is usually not required.

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

In the mixing step (1), the mixing ratio of the nitrogen-free saccharide compound and the nitrogen-containing saccharide compound, the mixing ratio of the nitrogen-free saccharide compound and the nitrogen-containing compound, the mixing ratio of the nitrogen-containing saccharide compound and the nitrogen-containing compound, or the mixing ratio of the nitrogen-free saccharide compound, the nitrogen-containing saccharide compound and the nitrogen-containing compound is not particularly limited and may be appropriately adjusted so as to obtain a carbonaceous material having desired properties. For example, increasing the amount of the nitrogen-containing compound tends to increase the nitrogen element content contained in the carbonaceous material. From the viewpoint of being able to adjust the above-mentioned properties of the carbonaceous material to a preferred range, it is preferable to adjust the above-mentioned mixing ratio so that the nitrogen element content contained in the mixture is 1.0 to 20.0 mass% based on the total mass of the mixture. The nitrogen element content contained in the mixture is preferably 3.0 to 15.0 mass%, more preferably 5.0 to 10.0 mass%.
When the nitrogen element content contained in the nitrogen-containing saccharide compound is within the range of the nitrogen element content contained in the mixture described above, such a nitrogen-containing saccharide compound may be prepared in step (1) instead of mixing the raw material compounds. The nitrogen-containing saccharide compound that may be prepared may be one type of nitrogen-containing saccharide compound alone or a combination of two or more types.
The amount of nitrogen element in a saccharide compound can be measured, for example, using an oxygen/nitrogen/hydrogen analyzer.

In a preferred embodiment of the present invention, the amount of the saccharide compound contained in the mixture obtained by mixing in step (1) is preferably 50 to 99% by mass, more preferably 80 to 95% by mass, based on the total mass of the saccharide compound and the nitrogen-containing compound. The amount of the nitrogen-containing compound contained in the mixture is preferably 1 to 30% by mass, more preferably 2 to 28% by mass, even more preferably 3 to 26% by mass, even more preferably 4 to 24% by mass, and particularly preferably 5 to 22% by mass, based on the total mass of the saccharide compound and the nitrogen-containing compound. The amount of the nitrogen-containing compound mixed in step (1) is preferably 0.013 to 0.56 mol, more preferably 0.026 to 0.50 mol, even more preferably 0.040 to 0.45 mol, even more preferably 0.054 to 0.41 mol, and particularly preferably 0.069 to 0.36 mol, based on 1 mol of starch monosaccharide units in the saccharide compound.

In step (1), when mixing the raw materials or preparing the nitrogen-containing sugar compound, at least one carbon source selected from the group consisting of coconut shells, walnut shells, rice husks, buckwheat husks, coffee grounds, wood, pulp, bamboo, and paper may be further mixed within a range that does not impair the effects of the present invention. These additional carbon sources may be of a grade that is commonly used in the art. When an additional carbon source is mixed, the amount thereof is preferably 50 mass% or less, more preferably 40 mass% or less, based on the total mass of the sugar compound, the nitrogen-containing compound if contained in the mixture, and the additional carbon source. In one embodiment of the present invention, the carbonaceous material in the present invention does not include carbonaceous materials derived from coconut shells, walnut shells, rice husks, buckwheat husks, coffee grounds, wood, pulp, bamboo, and paper.

In step (1), at least one crosslinking agent may be further mixed when mixing the raw materials or preparing the nitrogen-containing saccharide compound. The crosslinking agent is a compound capable of crosslinking saccharide compounds, and acts as a catalyst to promote the interchain bond formation reaction of saccharide compounds and/or the reaction between saccharide compounds and nitrogen-containing compounds, which proceeds in parallel with the hydrolysis reaction or dehydration reaction of saccharide compounds, or crosslinks saccharide compounds and/or nitrogen-containing compounds. In the heat treatment process, saccharide compounds often melt, fuse, foam, etc., and as a result, the resulting carbonaceous material often has a flat shape rather than a spherical shape. When a crosslinking agent is used in the heat treatment, the fusion or foaming of the raw materials can be suppressed, and as a result, the density of the electrode obtained using the resulting carbonaceous material can be increased.

If a crosslinking agent is used, the type is not particularly limited. Examples of such acids include aliphatic monocarboxylic acids such as 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, palmitic acid, stearic acid, linoleic acid, and oleic acid; aromatic monocarboxylic acids such as benzoic acid, salicylic acid, and toluic acid, and polycarboxylic acids such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, fumaric acid, maleic acid, phthalic acid, and terephthalic acid; hydroxycarboxylic acids such as lactic acid, tartaric acid, citric acid, and malic acid; carboxylic acids such as ethylenediaminetetraacetic acid, and sulfonic acids such as p-toluenesulfonic acid and methanesulfonic acid; amino acids such as glycine, alanine, valine, leucine, isoleucine, serine, threonine, cysteine, methionine, asparagine, glutamine, proline, phenylalanine, tyrosine, and tryptophan; and hydrochloric acid and sulfuric acid. When using a crosslinking agent, one of these crosslinking agents may be used, or two or more may be used in combination. Among these crosslinking agents, polycarboxylic acids and hydroxycarboxylic acids are preferred from the viewpoint of suppressing melting and foaming of the raw materials in the process of obtaining a carbonized material by heat treatment, and among these, succinic acid, adipic acid, and citric acid are more preferred.

When a crosslinking agent is used, the amount thereof is preferably 1 to 30 mass %, more preferably 3 to 10 mass %, based on the total mass of the saccharide compound, the molybdenum-containing compound, the nitrogen-containing compound if included in the mixture, and the crosslinking agent. When a crosslinking agent is used, increasing the amount of the crosslinking agent tends to increase the true density ρ _He of the carbonaceous material.

The heat treatment temperature in step (2) is preferably 550 to 850°C, more preferably 600 to 800°C. The heating rate until the heat treatment temperature (end temperature) is reached is preferably 50°C/hour or more, more preferably 50°C/hour to 200°C/hour. The heat treatment time is usually 5 minutes or more at the end temperature, preferably 5 minutes to 2 hours, more preferably 10 minutes to 1 hour, and even more preferably 30 minutes to 1 hour. If the heat treatment temperature and time are within the above ranges, the carbonization of the sugar compound can be controlled, and the above characteristic values of the carbonaceous material can be adjusted to the desired range. Here, the heat treatment temperature may be a constant temperature, but may vary within the above range.

Step (2) is carried out in 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, and nitrogen gas is preferred. By 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 pulverized and/or classified. The method of pulverization and classification is not particularly limited, and may be a conventional method, such as a method using a ball mill or a jet mill. By pulverizing and/or classifying the carbide, it is possible to break up or remove agglomerates generated by the heat treatment in step (2). The average particle size of the carbonaceous material obtained in step (3) is preferably 0.1 μm to 20 μm, more preferably 0.5 μm to 19 μm, even more preferably 1.0 μm to 18 μm, and particularly preferably 1.5 μm to 17 μm, from the viewpoints of the electrode density and volumetric efficiency of an electrode made using the carbonaceous material, and the charge/discharge efficiency of a battery made using the electrode. The average particle size is measured by a laser diffraction scattering method throughout this specification.

In step (4), the pulverized and/or classified carbide is heat-treated at 800 to 1300°C under an inert gas atmosphere to obtain the carbonaceous material of the present invention. The heat treatment temperature in step (4) is preferably 1000 to 1250°C, more preferably 1050 to 1200°C, and even more preferably 1110 to 1150°C. In this specification, heat treatment at 800 to 1300°C means holding the temperature of 800 to 1300°C for 1 minute or more. The rate of temperature rise until the above heat treatment temperature (attainment temperature) is reached is preferably 50°C/hour or more, more preferably 50°C/hour to 200°C/hour. In addition, the heat treatment time is a holding time at the attainment temperature of usually 1 minute or more, preferably 5 minutes to 2 hours, more preferably 10 minutes to 1 hour, even more preferably 10 minutes to 45 minutes, and particularly preferably 10 minutes to 30 minutes. If the heat treatment temperature and time are within the above ranges, the above characteristic values of the finally obtained carbonaceous material can be adjusted to desired values. Here, the heat treatment temperature may be a constant temperature, but may also vary within the above range.

In a preferred embodiment, step (4) is carried out in the presence of a volatile organic substance, or step (4) carried out in the absence of a volatile organic substance is followed by a further heat treatment in an inert gas atmosphere in the presence of a volatile organic substance (step (5)). When step (4) is carried out in the presence of a volatile organic substance or when step (5) is carried out, the heat treatment temperature is set so that volatile substances derived from the volatile organic substance generated by the heat treatment are present in the atmosphere in which the heat treatment is carried out.

The amount of volatile organic compounds in step (4) or step (5) is preferably 1 to 30 parts by mass, more preferably 2 to 20 parts by mass, and even more preferably 3 to 15 parts by mass, per 100 parts by mass of the pulverized and/or classified carbonized material obtained in step (3) or 100 parts by mass of the carbonaceous material obtained in step (4), respectively.

When step (4) is carried out in the presence of a volatile organic substance, the pulverized and/or classified carbonized material obtained in step (3) may be mixed with the volatile organic substance, and the resulting mixture may be subjected to step (4). A volatile organic substance refers to an organic compound that is hardly carbonized (e.g., 80% by mass or more, preferably 90% by mass or more) and volatilizes (vaporizes or pyrolyzes into gas) during heat treatment (e.g., at 500°C or more) under an inert gas atmosphere. Examples of volatile organic compounds include, but are not limited to, thermoplastic resins and low-molecular organic compounds. Specific examples of thermoplastic resins include polystyrene, polyethylene, polypropylene, poly(meth)acrylic acid, poly(meth)acrylic acid esters, etc. In this specification, (meth)acrylic is a general term for methacrylic and acrylic. The volatile organic matter may also be a resin that partially contains a thermoplastic resin, such as a copolymer, and examples of such resins include acrylonitrile-chlorinated polyethylene-styrene copolymer (ACS resin), acrylonitrile-acrylic acid 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 (SEBS resin), styrene-isoprene-styrene block copolymer (SIS resin), styrene-butadiene-styrene block copolymer (SBS resin), acrylonitrile-styrene copolymer (AS resin), acrylonitrile-butadiene-styrene copolymer (ABS resin), etc. Specific examples of low molecular weight organic compounds include ethylene, propane, hexane, toluene, xylene, mesitylene, styrene, naphthalene, phenanthrene, anthracene, pyrene, etc. As the thermoplastic resin, polystyrene, polyethylene, polypropylene, and poly(meth)acrylic acid are preferred, since they are preferred to volatilize at the heat treatment temperature and not oxidize and activate the surface of the carbon source when pyrolyzed. As the low molecular weight organic compound, it is further preferred to have low volatility at room temperature (e.g., 20°C) from the viewpoint of safety, and naphthalene, phenanthrene, anthracene, pyrene, etc. are preferred. The volatile organic compound can be used alone or in combination of two or more kinds. The use of such a volatile organic substance is preferred in that the oxygen element content can be reduced while maintaining the characteristic structure of the present invention.

Alternatively, the volatile organic compound may be gasified and mixed with an inert gas, and then supplied to step (4). The volatile organic compound is not particularly limited, but examples thereof include low molecular weight organic compounds. Examples of low molecular weight organic compounds include ethylene, propane, hexane, toluene, xylene, mesitylene, styrene, naphthalene, phenanthrene, anthracene, pyrene, and the like. Among these, compounds with high volatility are preferred from the viewpoint of mixability with the inert gas, and ethylene, propane, hexane, toluene, and the like are preferred. The volatile organic compounds may be used alone or in combination of two or more. The use of such volatile organic compounds is preferred in that the oxygen element content can be reduced while maintaining the characteristic structure of the present invention.

When a volatile organic substance is used in step (4), it is believed that the volatile organic substance deactivates the radical active sites on the surface of the carbonized particles. Such radical active sites usually react with oxygen in the air, increasing 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, particularly the oxygen element content measured by elemental analysis, is low, it is believed that there are few radical reaction sites on the surface of the carbonaceous material, making it less susceptible to oxidation, and that the number of sites that can become reaction sites during repeated charging and discharging is reduced. As a result, when the radical active sites of the carbonized material are deactivated by a volatile organic substance, it is believed that a higher discharge capacity can be maintained even after repeated charging and discharging.

When a further heat treatment (step (5)) is performed in an inert gas atmosphere in the presence of a volatile organic substance after the step (4) performed in the absence of a volatile organic substance, it is believed that the radical active sites on the surface of the particles of the carbonaceous material can be reduced while maintaining the carbon structure obtained in the step (4). The heat treatment temperature in the step (5) is preferably less than 1200°C, more preferably 700 to less than 1200°C, even more preferably 750 to 1100°C, and particularly preferably 800 to 1000°C. From the viewpoint of maintaining the carbon structure obtained in the step (4) and high discharge capacity, the heat treatment temperature in the step (5) is preferably equal to or lower than the upper limit. In addition, from the viewpoint of sufficient decomposition of the volatile organic substance and deactivation of the radical active sites of the carbonaceous material, the heat treatment temperature in the step (5) is preferably equal to or higher than the lower limit. The heat treatment time in the step (5) is preferably 1 minute to 1 hour, more preferably 10 minutes to 40 minutes, at the temperature reached. It is believed that when the temperature and time of the heat treatment in the presence of a volatile organic substance are within the above-mentioned ranges, the radical active sites of the carbonaceous material can be reduced, and as a result, a higher discharge capacity can be maintained even after repeated charge and discharge.
Examples of the volatile organic substance that can be used in step (5) include the same volatile organic substances as those exemplified as the volatile organic substances that can be used when step (4) is carried out in the presence of a volatile organic substance.

The manufacturing method includes a step (a) of also mixing a molybdenum-containing compound prior to the heat treatment in the step (4). By manufacturing a carbonaceous material by a manufacturing method including the step (a), it is possible to include elemental molybdenum in the carbonaceous material. By having a predetermined amount of elemental molybdenum in the carbonaceous material and setting the half-width value of the peak near 1360 cm ⁻¹ in the Raman spectrum within a predetermined range, it is possible to provide a carbonaceous material suitable for an electricity storage device that can achieve a high energy density in addition to a high charge capacity, a high discharge capacity, and a high current efficiency.

Step (a) may, for example, be one or more of the following steps:
- mixing the saccharide compound and/or the nitrogen-containing compound with the molybdenum-containing compound prior to the mixing in step (1);
- mixing in step (1) also a molybdenum-containing compound;
mixing the mixture obtained in step (1) or the nitrogen-containing saccharide compound prepared in step (1) with a molybdenum-containing compound;
- a step of mixing the carbide obtained in step (2) with a molybdenum-containing compound, and - a step of mixing the crushed and/or classified carbide obtained in step (3) with a molybdenum-containing compound.

The molybdenum-containing compound that can be used in step (a) is not particularly limited as long as it is a compound that has a molybdenum atom in the molecule. For example, inorganic molybdenum compounds, organic molybdenum compounds, and hydrates thereof can be used. As the molybdenum-containing compound, one type of molybdenum-containing compound may be used, or two or more types may be used in combination.

Examples of inorganic molybdenum compounds include molybdic acid, phosphomolybdic acid, molybdenum trioxide, molybdenum sulfide, molybdenum chloride, molybdosilicic acid, and molybdenum boride. When these inorganic molybdenum compounds are in the form of a salt, the salt may be, for example, an alkali metal salt and/or an alkaline earth metal salt, or an ammonium salt. Examples of such salts include lithium molybdate, sodium molybdate, sodium phosphomolybdate, potassium molybdate, magnesium molybdate, calcium molybdate, ammonium molybdate, ammonium thiomolybdate, and hydrates thereof.
Examples of the organic molybdenum compound include molybdenum dialkyldithiophosphate, molybdenum dithiocarbamate, and molybdenum oxide bis(2,4-pentanedionate).
Among these molybdenum-containing compounds, those with a high intramolecular molybdenum content are preferred from the viewpoint of incorporating a large amount of molybdenum element into the carbonaceous material.

The method of mixing the molybdenum-containing compound in step (a) is not particularly limited. When the molybdenum-containing compound is solid, the solid molybdenum-containing compound may be mixed with a sugar compound or the like. When the molybdenum-containing compound is, for example, water-soluble, an aqueous solution of the molybdenum-containing compound may be mixed with a sugar compound or the like.

The total amount of the molybdenum-containing compounds mixed in step (a) is not particularly limited as long as a carbonaceous material having an elemental molybdenum content in the above range is finally obtained. For example, the total amount is preferably 0.5 to 6.0 mass%, more preferably 1.0 to 5.5 mass%, based on the total mass of the saccharide compound and the nitrogen-containing compound, or the mass of the nitrogen-containing saccharide compound when no nitrogen-containing compound is used, or based on the mass of the carbonized material obtained in step (2). The total amount of the molybdenum-containing compounds mixed in step (a) is preferably 0.0005 to 0.050 moles, more preferably 0.00010 to 0.040 moles, and even more preferably 0.00015 to 0.030 moles, based on 1 mole of starch monosaccharide unit in the saccharide compound.

In addition, a phosphorus-containing compound may also be mixed prior to the heat treatment in step (4). When a phosphorus-containing compound is also mixed, it can be mixed, for example, in one or more of the following steps:
- mixing the saccharide compound and/or the nitrogen-containing compound with the phosphorus-containing compound prior to the mixing in step (1);
- mixing a phosphorus-containing compound in the mixing step (1);
- mixing the mixture obtained in step (1) or the nitrogen-containing saccharide compound prepared in step (1) with a phosphorus-containing compound;
- a step of mixing the carbide obtained in step (2) with a phosphorus-containing compound, and - a step of mixing the ground and/or classified carbide obtained in step (3) with a phosphorus-containing compound.
When a phosphorus-containing compound is also mixed, the phosphorus-containing compound may be mixed simultaneously with the molybdenum-containing compound or may be mixed at a different time.

The phosphorus-containing compound is not particularly limited as long as it is a compound that has a phosphorus atom in the molecule. For example, inorganic phosphoric acid, organic phosphoric acid, and 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 acid include phosphoric acid, dihydrogen phosphate, ammonium dihydrogen phosphate, primary phosphate, secondary phosphate, tertiary phosphate, pyrophosphoric acid, pyrophosphate, tripolyphosphoric acid, tripolyphosphate, phosphorous acid, phosphite, hypophosphorous acid, hypophosphite, diphosphorus pentoxide, etc. Examples of organic phosphoric acid include phosphonic acid (phosphonic acid compound), and examples of phosphonic acid include nitrilotrismethylenephosphonic acid, phosphonobutanetricarboxylic acid, methyldiphosphonic acid, methylenephosphonic acid, ethylidenediphosphonic acid, triphenyl phosphate, etc. 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 organic phosphorus include triphenylphosphine, triphenylphosphine oxide, tricyclohexylphosphine, tricyclohexylphosphine oxide, trialkylphosphine, trialkylphosphine oxide, etc. Examples of phosphonium salts include tetraalkylphosphonium salts, tetraphenylphosphonium salts, etc. These salts may be, for example, halides, sulfates, phosphates, or acetates.
Among these phosphorus-containing compounds, from the viewpoint of incorporating a large amount of phosphorus element into the carbonaceous material, phosphoric acid and ammonium dihydrogen phosphate, which have a high phosphorus content in the molecule, are preferred. From the viewpoint of the reaction with the saccharide compound in the heat treatment process, the phosphorus-containing compound is preferably a compound having a volatilization temperature of preferably 100° C. or higher, more preferably 150° C. or higher.

The method of mixing the phosphorus-containing compound is not particularly limited. If the phosphorus-containing compound is solid, the solid phosphorus-containing compound may be mixed with a sugar compound or the like. Also, if the phosphorus-containing compound is, for example, water-soluble, an aqueous solution of the phosphorus-containing compound may be mixed with a sugar compound or the like.

When a phosphorus-containing compound is also mixed, the total amount is preferably 0.5 to 10 mass%, more preferably 0.6 to 8 mass%, based on the total mass of the saccharide compound and the nitrogen-containing compound, or the mass of the nitrogen-containing saccharide compound when no nitrogen-containing compound is used, or based on the mass of the carbonized product obtained in step (2). When a phosphorus-containing compound is also mixed, the total amount is preferably 0.001 to 0.20 mol, more preferably 0.005 to 0.15 mol, and even more preferably 0.01 to 0.10 mol, based on 1 mol of starch monosaccharide unit in the saccharide compound.

The manufacturing method may further include, in addition to steps (1) to (4) or steps (1) to (5), a step (b) of gelatinizing the sugar compound before, simultaneously with, or after step (1). When step (b) is further carried out, the cavities in the sugar compound disappear, and as a result, the density of the electrode formed from the finally obtained carbonaceous material can be increased, and the discharge capacity per volume can be increased.

When carrying out step (b), the gelatinization method is not particularly limited. For example, a method of heating a saccharide compound alone or in a state of any mixture with a nitrogen-containing compound or the like in the presence of water, a method of subjecting a saccharide compound alone or in a state of any mixture with a nitrogen-containing compound or the like to mechanical treatment having the action of impact, crushing, friction and/or shearing can be mentioned. By applying such heat or external force, the cavities contained in the saccharide compound can be blocked and disappeared. For example, in an image obtained by observing the cross section of a particle of a gelatinized saccharide compound with a secondary electron microscope, it is preferable to carry out the gelatinization until the number of particles having a void of 1 μm ² or ^more is a predetermined amount or less, preferably 3 ^or less, more preferably 2 or less, and even more preferably 1 or less when 20 particles having a cross-sectional area of 3 μm 2 or more and 100 μm 2 or less are arbitrarily selected. The above microscope observation may be carried out after removing aggregates contained in the compound or mixture after gelatinization by crushing or classification. When step (b) is performed, the mixture obtained through step (1) and optional step (b) as described above is heat-treated in step (2). Therefore, when step (b) is performed, step (b) is a step performed before step (2).

In a preferred embodiment of the present invention, the manufacturing method may comprise, as step (b), one or more of the following steps:
- a step (b1) prior to the step (1), of mixing a saccharide compound with 5 to 50% by mass of water based on the mass of the saccharide compound and heating the mixture at a temperature of 50 to 200°C for 1 minute to 5 hours;
- a step (b2) of subjecting the saccharide compound to a mechanical treatment having the action of impact, crushing, friction and/or shear, prior to step (1);
- step (b3), simultaneously with the mixing in step (1) or after the mixing or preparation in step (1), of mixing the mixture containing a saccharide compound or the prepared nitrogen-containing saccharide compound with 5 to 50 mass% of water based on the mass of the saccharide compound contained in the mixture or the prepared nitrogen-containing saccharide compound, and heating at a temperature of 50 to 200°C for 1 minute to 5 hours; and - step (b4), simultaneously with the mixing in step (1) or after the mixing or preparation in step (1), of subjecting the mixture containing a saccharide compound or the prepared nitrogen-containing saccharide compound to a mechanical treatment having the effects of impact, crushing, friction, and/or shear.

The amount of water in step (b1) needs to be at least a certain amount, but it is better to use less water in order to reduce the energy required to distill off the mixed water during the process of producing the carbonaceous material. Therefore, the amount of water is 5 to 50 mass %, preferably 10 to 50 mass %, and more preferably 10 to 30 mass % relative to the mass of the nitrogen-containing sugar compound when no sugar compound or nitrogen-containing compound is used. The heating temperature is 50 to 200°C, preferably 60 to 180°C, and more preferably 80 to 180°C, and the heating time is 1 minute to 5 hours, preferably 3 minutes to 1 hour, and more preferably 10 minutes to 30 minutes.

In step (b2), examples of equipment used for mechanical processing having the effects of impact, crushing, friction, and/or shear include a grinder, extruder, flour mill, grinder, and kneader. Processing conditions such as processing time are not particularly limited. For example, when using a ball vibration mill, processing conditions of 20 Hz and 10 minutes can be used.

The preferred amount of water, heating temperature, and heating time in step (b3) are the same as those described for step (b1).

The preferred apparatus and processing conditions for step (b4) are the same as those described for step (b2).

<Negative electrode for electricity storage device>
The carbonaceous material of the present invention or the carbonaceous material produced by the production method can be suitably used as a carbonaceous material for the negative electrode of an electricity storage device, more specifically, as an active material for the negative electrode of an electricity storage device. By using the carbonaceous material, it is possible to produce a negative electrode for an electricity storage device that provides high charge capacity and discharge capacity per mass, high current efficiency, and high energy density. Therefore, the present invention also covers a negative electrode for an electricity storage device that contains the carbonaceous material.

The negative electrode can be manufactured by a method common in the art. For example, a carbonaceous material is first mixed with a binder, and then further mixed with an appropriate amount of a suitable solvent to prepare a slurry-like electrode mixture. The resulting electrode mixture is applied to a current collector made of a metal plate or the like, dried, and then pressure-molded. This makes it possible to manufacture a negative electrode for an electricity storage device, for example, a negative electrode for a non-aqueous electrolyte secondary battery such as a lithium ion secondary battery, a sodium ion battery, a lithium sulfur battery, or a lithium air battery.

The amount of carbonaceous material in the electrode mixture is preferably 80 to 100% by mass, and more preferably 90 to 97% by mass, assuming that the amount of active material (carbonaceous material) + the amount of binder + the amount of optional components (such as the conductive additive described below) = 100% by mass.

The binder is not particularly limited as long as it does not react with the electrolyte. Examples include PVDF (polyvinylidene fluoride), polytetrafluoroethylene, and a mixture of SBR (styrene butadiene rubber) and CMC (carboxymethyl cellulose). Among them, a mixture of SBR and CMC is preferable because the SBR and CMC attached to the surface of the active material do not hinder the movement of electrolyte ions, and good input/output characteristics can be obtained.
If the amount of binder is too large, the resistance of the resulting electrode increases, and the internal resistance of the power storage device increases, which may result in a decrease in electrical properties. If the amount of binder is too small, the bonding between the particles of the negative electrode material and with the current collector may be insufficient. The preferred amount of binder varies depending on the type of binder used. For example, in binders using water as a solvent, a mixture of SBR and CMC or the like is often used as a mixture of multiple binders, and the total mass of these binders is preferably 0.5 to 5 mass%, more preferably 1 to 4 mass%, when the amount of active material + the amount of binder + the amount of optional components when used = 100 mass%. On the other hand, in the case of PVDF-based binders, the amount is preferably 3 to 13 mass%, more preferably 3 to 10 mass%, when the amount of active material + the amount of binder + the amount of optional components when used = 100 mass%.

To form an aqueous emulsion of SBR or the like or an aqueous solution of CMC, a polar solvent such as water is preferably used as the solvent. To dissolve PVDF to form a slurry, a polar solvent such as N-methylpyrrolidone is preferably used. The amount of solvent is preferably 10 to 200 parts by mass, more preferably 50 to 150 parts by mass, assuming that the amount of active material + the amount of binder + the amount of optional components, if used, = 100 parts by mass.

If it is desired to impart higher conductivity to the negative electrode, a conductive assistant may be further mixed in when preparing the electrode mixture, as necessary. Examples of conductive assistants include conductive carbon black, vapor-grown carbon fiber (VGCF), nanotubes, etc. The amount of conductive assistant varies depending on the type of conductive assistant used, but if the amount is too small, the expected conductivity may not be obtained, and if the amount is too large, dispersion in the electrode mixture may become poor. From this perspective, when a conductive assistant is used, the amount is preferably 0.5 to 10 mass%, more preferably 0.5 to 7 mass%, and even more preferably 0.5 to 5 mass%, when the amount of active material + amount of binder + amount of conductive assistant = 100 mass%.

The 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 active material layer, the fewer current collector plates or separators are required, which is preferable for high capacity. However, since a larger electrode area facing the counter electrode is more advantageous for improving input/output characteristics, if the active material layer is too thick, the input/output characteristics may deteriorate. From the viewpoint of output when discharging the electricity storage device, 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.

<Electricity storage device>
An electricity storage device using the carbonaceous material in the negative electrode can have a high energy density as well as a high charge capacity and discharge capacity per mass and a high current efficiency. The present invention also covers such an electricity storage device, that is, an electricity storage device including the negative electrode for an electricity storage device of the present invention.
When manufacturing the electricity storage device of the present invention, other materials constituting the electricity storage device, such as the positive electrode material, the separator, and the electrolyte, are not particularly limited. Various materials that have been conventionally used or proposed for electricity storage devices can be used.

As the positive electrode material, a composite metal chalcogen compound of a layered oxide system [represented as _LiMO2 , where M represents a metal: for example, _LiCoO2 , _LiNiO2 , _LiMnO2 , or LiNi _x Co _y Mo _{z O2} (where x, y, and z represent the composition ratio)], an olivine system (represented as _LiMPO4 , where M represents a metal: for example, _LiFePO4 , etc.), or a spinel system (represented as _{LiM2O4 ,} where M represents a metal: for example, _LiMn2O4 , _etc. ) is preferable. These chalcogen compounds may be used alone or in combination. These positive electrode materials are molded together with a suitable binder and a carbon material for imparting conductivity to the electrode, and a layer is formed on a conductive current collector to form a positive electrode.

For example, when the power storage device is a non-aqueous electrolyte secondary battery, the non-aqueous solvent type electrolyte is generally prepared 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, ethyl methyl carbonate, dimethoxyethane, diethoxyethane, γ-butyl lactone, tetrahydrofuran, 2-methyltetrahydrofuran, sulfolane, and 1,3-dioxolane, which can be used alone or in combination of two or more. In addition, LiClO ₄ , LiPF ₆ , LiBF ₄ , LiCF ₃ SO ₃ , LiAsF ₆ , LiCl, LiBr, LiB(C ₆ H ₅ ) ₄ , or LiN(SO ₃ CF ₃ ) ₂ are used as the electrolyte.

When the power storage device is a non-aqueous electrolyte secondary battery, the non-aqueous electrolyte secondary battery is generally manufactured by opposing the positive and negative electrodes formed as described above, with a liquid-permeable separator interposed between them as necessary, and immersing them in an electrolyte. As such a separator, a non-woven fabric or other permeable or liquid-permeable separator made of a porous material that is commonly used in secondary batteries can be used. Alternatively, a solid electrolyte made of a polymer gel impregnated with an electrolyte can be used in place of or together with the separator.

The present invention will be explained in detail below with reference to examples, but the scope of the present invention is not limited to these examples. Note that the methods for measuring the physical properties of carbonaceous materials and negative electrodes 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 based on values obtained by the following methods.

<Raman spectrum>
A Raman spectrometer (Nanophoton's "Laser Raman Microscope Ramanforce") was used. The carbonaceous material to be measured was set on the observation stage, the magnification of the objective lens was set to 20 times, the focus was adjusted, and measurements were performed while irradiating argon ion laser light. The details of the measurement conditions are as follows. From the obtained Raman spectrum, the half-width of the peak near 1360 cm ^-1 was determined.
Wavelength of argon ion laser light: 532 nm
Laser power on sample: 100-300 W/ ^cm2
Resolution: 5-7cm ^-1
Measurement range: 150-4000 ^cm
Measurement mode: XY Averaging
Exposure time: 20 seconds Number of integrations: 2 Peak intensity measurement: Baseline correction Automatic correction with Polynom-3rd order Peak search & fitting processing Gauss Lorentz

<Molybdenum element content>
Microwave decomposition 5 mg of sample was weighed on a filter paper and introduced into a quartz decomposition vessel (80 mL volume) together with the filter paper. 6 mL of nitric acid and 2 mL of sulfuric acid were added thereto, and microwave decomposition was performed. Specifically, the temperature was raised from the initial temperature (room temperature) to 210 ° C. in 4 minutes, and after holding at 210 ° C. for 4 minutes, the vessel temperature was air-cooled until the pressure dropped to 70 psi at 80 ° C. The maximum pressure was set to 400 psi and the maximum power output was set to 300 W. After further cooling to room temperature (about 25 ° C.), the contents of the vessel were transferred to a PFA measuring flask (100 mL volume), and pure water was added up to the mark. After filtration with a hydrophilic PTFE filter with a pore size of 0.45 μm, the filtrate was subjected to ICP spectroscopy.
ICP Spectroscopic Analysis The molybdenum content (mass%) of the carbonaceous material was measured using an ICP emission spectrometer ("iCAP6300Duo" manufactured by Thermo Fisher Scientific). Details of the pretreatment conditions and measurement conditions are as follows.
RF power: 1150W
Auxiliary gas flow rate: 0.5 L/min
Nebulizer gas flow rate: 0.7 L/min
Analysis pump flow rate: 50 rpm
Plasma view: Axial Low wavelength range: 15 sec
High wavelength range: 5 sec

<Hydrogen, oxygen and nitrogen element content>
Elemental analysis was carried out 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 fusion-non-dispersive infrared absorption method (NDIR), nitrogen: inert gas fusion-thermal conduction method (TCD), and hydrogen: inert gas fusion-non-dispersive infrared absorption method (NDIR), and calibration was performed with (oxygen/nitrogen) Sn capsule, TiH ₂ (H standard sample), SS-3 (O standard sample), and SiN (N standard sample). 5 mg of a sample that was pretreated at 250°C for about 10 minutes and had its moisture content measured was placed in a Sn capsule, degassed for 30 seconds in the analyzer, and then elemental analysis was performed. Three samples were analyzed for each carbonaceous material, and the average value of the measured content of each element was taken as the content of each element in the carbonaceous material.

<Carbon interplanar spacing d ₀₀₂ measured by X-ray diffraction>
The carbonaceous material to be measured was loaded into a sample holder of "MiniFlex II manufactured by Rigaku Corporation", and an X-ray diffraction pattern was obtained using CuKα rays monochromatized by a Ni filter as a radiation source. The peak positions of the X-ray diffraction pattern were determined by the centroid method (a method of determining the centroid position of the diffraction line and determining the peak position at the corresponding 2θ value), and were corrected using the diffraction peak of the (111) plane of high-purity silicon powder for standard material. The wavelength λ of CuKα rays was set to 0.15418 nm, and d ₀₀₂ was calculated using the Bragg formula described below.

<True density determined by helium method>
The true density ρ _He of the carbonaceous material was measured using a fully automatic pycnometer ("UltraPyc1200e" manufactured by Quantachrome Instruments) under the following measurement conditions.
Cell size: Large
Gas type: Helium Sample amount: 1.0 g
Equilibration time: Automatic Flow purge: 10min
Maximum number of measurements: 30 times Required deviation: 0.0500%

　得られたｖ_ｍを用いて、下記式（３）により試料の比表面積（ＳＳＡ：単位はｍ^２／ｇ）を算出した。

　上記式中、ｖ_ｍは試料表面に単分子層を形成するのに必要な吸着ガス量（ｃｍ^３／ｇ）、ｖは実測される吸着ガス量（ｃｍ^３／ｇ）、ｐ_０（Ｐａ）は飽和蒸気圧、ｐは絶対圧（Ｐａ）、ｃは定数（吸着熱を反映）、Ｎはアボガドロ数６．０２２×１０^２３、ａ（ｎｍ^２）は吸着質分子（窒素分子）が試料表面で占める面積（分子占有断面積）である。 <BET specific surface area>
The carbonaceous material, which is the measurement sample, was filled into a sample tube. This sample tube was placed in "BERSORP-MAX" (manufactured by Microtrackbell Co., Ltd.), and in a state where it was cooled to -196°C, the pressure was once reduced, and then nitrogen (purity 99.999%) was adsorbed into the measurement sample at a predetermined relative pressure. The amount of nitrogen adsorbed into the sample when the equilibrium pressure was reached at each predetermined relative pressure was measured. This amount of adsorbed nitrogen is the amount of adsorbed gas at a predetermined relative pressure (p/p ₀ ) by the BET multipoint method, and is referred to as the amount of adsorbed gas v. The amount of adsorbed gas v was substituted into the BET approximation formula (formula (2)) shown below to obtain v _m .

Using the obtained _vm , the specific surface area (SSA: unit is m ² /g) of the sample was calculated according to the following formula (3).

In the above formula, _vm is the amount of adsorbed gas ( ^cm3 /g) required to form a monolayer on the sample surface, v is the measured amount of adsorbed gas ( ^cm3 /g), _p0 (Pa) is the saturated vapor pressure, p is the absolute pressure (Pa), c is a constant (reflecting the heat of adsorption), N is Avogadro's number 6.022 x ¹⁰²³ , and a ( ^nm2 ) is the area occupied by the adsorbate molecules (nitrogen molecules) on the sample surface (molecular occupied cross-sectional area).

<Molybdenum modification rate>
The molybdenum modification rate (unit: mass %/(m ² /g)) was calculated by dividing the molybdenum element content (unit: mass %) determined by the above-mentioned measurement method by the BET specific surface area (unit: m ² /g) determined by the above-mentioned measurement method.
Molybdenum modification rate = molybdenum element content / BET specific surface area Formula (1)

Example 1
10.0 g of starch (corn starch), 0.14 g of hexaammonium heptamolybdate tetrahydrate (0.0018 mol per mol of starch monosaccharide unit), and 100 mL of pure water were added to a beaker and stirred at 100 rpm for 1 hour using a stirrer. The mixture was then dried at 50°C for 8 hours using a dryer (Tokyo Rikakikai Co., Ltd. "WFO-520") to obtain a dried product. The obtained dried product was pulverized using an agate mortar. The pulverized dried product, 1.16 g of melamine (0.15 mol per mol of starch monosaccharide unit), and 0.76 g of adipic acid (0.085 mol per mol of starch monosaccharide unit) were introduced into a sample bottle and shaken to obtain a mixture (step (1) and step (a)).
The mixture was heated to 600° C. at a heating rate of 10° C./min (60° C./hr) while supplying nitrogen gas. The mixture was then heat-treated at 600° C. for 30 minutes while supplying nitrogen gas to obtain a carbonized material (step (2)). The amount of nitrogen gas supplied during heating and heat treatment was 0.5 L/min per 10.0 g of starch.
The obtained carbonized material was pulverized in a ball mill to obtain a pulverized carbonized material having a _D50 of 5 μm (step (3)). The pulverized carbonized material and polystyrene (manufactured by Sekisui Chemical Co., Ltd., average particle size 400 μm, residual carbon rate 1.2 mass%) were introduced into a 100 mL container so as to have a mass ratio of 1:0.1, and mixed by shaking at 2 Hz for 5 minutes.
The mixture was heated to 1150° C. at a heating rate of 10° C./min while supplying nitrogen gas. The mixture was then heat-treated at 1150° C. for 10 minutes while supplying nitrogen gas to obtain a carbonaceous material (step (4)). The amount of nitrogen gas supplied during heating and heat treatment was 3 L/min per 5.0 g of the pulverized carbide.
The obtained carbonaceous material was analyzed.

Example 2
A carbonaceous material was obtained in the same manner as in Example 1, except that the amount of hexaammonium heptamolybdate tetrahydrate as the molybdenum-containing compound was changed from 0.14 g (0.0018 mol per mol of starch monosaccharide units) to 0.28 g (0.0036 mol per mol of starch monosaccharide units), and the obtained carbonaceous material was analyzed.

Example 3
A carbonaceous material was obtained in the same manner as in Example 1, except that the amount of melamine as a nitrogen-containing compound was changed from 1.16 g (0.15 mol per mol of starch monosaccharide units) to 2.00 g (0.26 mol per mol of starch monosaccharide units), and the obtained carbonaceous material was analyzed.

Example 4
A carbonaceous material was obtained in the same manner as in Example 1 except that 10.0 g of glucose was used instead of 10.0 g of starch as the saccharide compound, and the obtained carbonaceous material was analyzed.

Example 5
A carbonaceous material was obtained in the same manner as in Example 1, except that 1.16 g of dicyandiamide (0.23 mol per mol of starch monosaccharide units) was used instead of 1.16 g of melamine (0.15 mol per mol of starch monosaccharide units) as the nitrogen-containing compound, and the obtained carbonaceous material was analyzed.

Example 6
A carbonaceous material was obtained in the same manner as in Example 1, except that 0.2 g of disodium molybdate dihydrate (0.013 mol per mol of starch monosaccharide units) was used instead of 0.14 g of hexaammonium heptamolybdate tetrahydrate (0.0018 mol per mol of starch monosaccharide units) as the molybdenum-containing compound, and the obtained carbonaceous material was analyzed.

Example 7
A carbonaceous material was obtained in the same manner as in Example 1, except that 0.1 g of disodium molybdate dihydrate (0.0033 mol per mol of starch monosaccharide units) was used instead of 0.14 g of hexaammonium heptamolybdate tetrahydrate (0.0018 mol per mol of starch monosaccharide units) as the molybdenum-containing compound, and the obtained carbonaceous material was analyzed.

Example 8
A carbonaceous material was obtained in the same manner as in Example 6, except that 0.4 g (0.057 mol per 1 mol of starch monosaccharide unit) of ammonium dihydrogen phosphate as a phosphorus-containing compound was also introduced into the sample bottle in step (1) and step (a), and the obtained carbonaceous material was analyzed.

Comparative Example 1
Step (a) was not performed, and in step (1), 10.0 g of starch (corn starch), 1.16 g of melamine (0.15 mol per mol of starch monosaccharide units), and 0.76 g of adipic acid (0.085 mol per mol of starch monosaccharide units) were introduced into a sample bottle and shaken to obtain a mixture. Step (2) and subsequent steps were performed in the same manner as in Example 1 to obtain a carbonaceous material, and the obtained carbonaceous material was analyzed.

Comparative Example 2
A carbonaceous material was obtained in the same manner as in Example 1, except that in step (4), instead of increasing the temperature to 1150°C and performing heat treatment at 1150°C for 10 minutes, the temperature was increased to 1350°C and heat treatment was performed at 1350°C for 60 minutes. The obtained carbonaceous material was analyzed.

Comparative Example 3
A carbonaceous material was obtained in the same manner as in Example 1, except that the amount of hexaammonium heptamolybdate tetrahydrate as the molybdenum-containing compound was changed from 0.14 g (0.0018 mol per mol of starch monosaccharide units) to 0.70 g (0.0090 mol per mol of starch monosaccharide units), and the obtained carbonaceous material was analyzed.

Comparative Example 4
The coconut shells were crushed and dry-distilled at 500°C to obtain coconut shell char with a particle size of 2.360 to 0.850 mm (containing 98% by mass of particles with a particle size of 2.360 to 0.850 mm). 100 g of this coconut shell char was subjected to a gas phase demineralization treatment at 870°C for 50 minutes while supplying nitrogen gas containing 1% by volume of hydrogen chloride gas at a flow rate of 10 L/min. Next, the supply of only the hydrogen chloride gas was stopped, and a gas phase deoxidation treatment was further performed at 870°C for 30 minutes while supplying nitrogen gas at a flow rate of 10 L/min to obtain a carbon precursor. The obtained carbon precursor was coarsely pulverized to an average particle size of 10 μm using a ball mill, and then pulverized and classified using a compact jet mill ("Cojet System α-mkIII" manufactured by Seishin Enterprise Co., Ltd.) to obtain a carbon precursor with an average particle size of 9.6 μm. 9.1 g of this carbon precursor was mixed with 0.9 g of polystyrene (manufactured by Sekisui Chemical Co., Ltd., average particle size 400 μm, residual carbon rate 1.2%). 10 g of this mixture was introduced into a graphite sheath (length 100 mm, width 100 mm, height 50 mm) and heated to 1250 ° C. at a heating rate of 60 ° C. / min under a nitrogen flow rate of 5 L / min in a high-speed heating furnace manufactured by Motoyama Co., Ltd., and then held for 11 minutes and naturally cooled. After confirming that the temperature in the furnace had dropped to 200 ° C. or less, the carbonaceous material was removed from the furnace. The obtained carbonaceous material was analyzed.

Comparative Example 5
A carbonaceous material was obtained in the same manner as in Comparative Example 1, except that in step (4), instead of increasing the temperature to 1150° C. and performing heat treatment at 1150° C. for 10 minutes, the temperature was increased to 1000° C. and heat treatment was performed at 1000° C. for 60 minutes, and the obtained carbonaceous material was analyzed.

Comparative Example 6
A carbonaceous material was obtained in the same manner as in Example 1, except that the amount of hexaammonium heptamolybdate tetrahydrate as the molybdenum-containing compound was changed from 0.14 g (0.0018 mol per mol of starch monosaccharide units) to 0.024 g (0.00031 mol per mol of starch monosaccharide units), and the obtained carbonaceous material was analyzed.

<Preparation of electrodes>
Using each of the carbonaceous materials obtained in the Examples and Comparative Examples, negative electrodes were produced according to the following procedure.
A slurry was obtained by mixing 95 parts by mass of a 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 90 parts by mass of water. The obtained slurry was applied to one side of a copper foil having a thickness of 15 μm, dried, pressed, and punched out to a diameter of 14 mm to obtain an electrode having a thickness of 45 μm.

<Charge capacity and discharge capacity per mass, and current efficiency>
The electrode prepared above was used as the working electrode, and metallic lithium was used as the counter electrode and reference electrode. Ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate were mixed in a volume ratio of 1:1:1 and used as the solvent. _LiPF6 was dissolved in this solvent to a concentration of 1 mol/L and used as the electrolyte. A polypropylene film was used as the separator. A coin cell was prepared in a glove box under an argon atmosphere.
A charge/discharge test was performed on the lithium secondary battery having the above configuration using a charge/discharge tester (manufactured by Toyo Systems Co., Ltd., "TOSCAT"). Lithium doping was performed at a rate of 70 mA/g relative to the active material mass, and doping was continued until the lithium potential reached 1 mV. A constant voltage of 1 mV was further applied to the lithium potential, and doping was terminated at a rate of 2 mA/g relative to the active material mass. The capacity at this time was taken as the initial charge capacity (mAh). Next, dedoping (CC discharge) was performed at a rate of 70 mA/g relative to the active material mass until the lithium potential reached 1.5 V, and the capacity discharged at this time was taken as the initial discharge capacity (mAh). The obtained initial charge capacity and initial discharge capacity were each divided by the mass of the negative electrode, and the obtained values were taken as the charge capacity per mass (mAh/g) and the discharge capacity per mass (mAh/g) (evaluation of initial charge/discharge). In addition, the initial discharge capacity was divided by the initial charge capacity, and the percentage of the obtained value was taken as the current efficiency (%).

<CC discharge capacity, CV discharge capacity and CV/CC ratio>
The capacity per mass at 0.1 V or less when CC discharge was performed was defined as the CV discharge capacity (mAh/g), and the capacity per mass at 0.1 V or more was defined as the CC discharge capacity (mAh/g). The CV discharge capacity was divided by the CC discharge capacity to obtain the CV/CC ratio.

When the carbonaceous material of the present invention is applied to the negative electrode, it is possible to obtain an electricity storage device that has high charge capacity and discharge capacity per mass, high current efficiency, and high energy density. Therefore, the carbonaceous material of the present invention can be suitably used as a carbonaceous material for the negative electrode of an electricity storage device.

Claims (9)

A carbonaceous material, wherein the half width of a peak in the vicinity of 1360 cm ⁻¹ in a Raman spectrum observed by laser Raman spectroscopy is 200 to 280 cm ⁻¹ , and the molybdenum content determined by ICP emission spectrometry is 0.5 to 7.5 mass %. The carbonaceous material according to claim 1, wherein the nitrogen element content determined by elemental analysis is 0.5 to 4.6 mass%. 2. The carbonaceous material according to claim 1, which has a BET specific surface area of 3 to 60 m ² /g calculated by the BET method based on a nitrogen adsorption/desorption isotherm obtained by a nitrogen adsorption method. The following formula (1):
Molybdenum modification rate (mass %/(m ² /g))=molybdenum element content (mass %)/BET specific surface area (m ² /g) Formula (1)
2. The carbonaceous material according to claim 1, wherein the molybdenum modification rate calculated by the above formula is 0.10 to 1.08 mass %/(m ² /g). 2. The carbonaceous material according to claim 1, wherein the carbon interplanar spacing (d ₀₀₂ ) determined by X-ray diffraction measurement is 3.65 to 4.00 Å. The carbonaceous material according to claim 1, wherein the true density of the carbonaceous material determined by the helium method is 1.30 to 2.10 g/cc. The carbonaceous material according to any one of claims 1 to 6, which is a carbonaceous material for the negative electrode of an electricity storage device. A negative electrode for an electricity storage device, comprising the carbonaceous material according to claim 7. An electricity storage device comprising the electricity storage device negative electrode according to claim 8.

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