JP2019036506A - Negative electrode for battery formed by including positive electrode with organic compound as active material and battery formed by including positive electrode with the negative electrode and organic compound as active material - Google Patents

Abstract

To provide a negative electrode and a battery using the negative electrode, capable of achieving a high output characteristic and high durability, the battery formed by including a positive electrode with an organic compound as an active material.SOLUTION: The negative electrode for battery, formed by including a positive electrode with an organic compound as an active material, has a main resonance peak position of a chemical shift value based on lithium chloride observed by aLi nuclear-solid NMR analysis larger than 115 ppm when lithium is doped until a full-charge state is reached and contains a difficult-to-graphitize carbonaceous material, and a battery is formed by including a positive electrode with an organic compound using the negative electrode as an active material.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a negative electrode for obtaining high output characteristics in a battery including a positive electrode using an organic compound as an active material, and a battery using the negative electrode.

  A battery comprising a positive electrode made of an organic compound as an active material has high output characteristics, so that it can be applied not only to portable devices such as mobile phones and personal computers, but also to hybrid vehicles, electric vehicles, power storage and storage systems, etc. It is illustrated. The battery includes, for example, a positive electrode including an organic compound as an active material and a negative electrode including a negative electrode active material including lithium. For example, Patent Document 1 discloses a battery including a positive electrode using an organic compound as an active material, using a lithium foil or a lithium metal plate as a negative electrode active material containing lithium.

  When metal lithium foil is used as the negative electrode active material, a very high battery capacity can be obtained. On the other hand, non-uniform charge and discharge that occurs on metal lithium can cause dendrite-like lithium metal formation and micro short-circuiting during long-term charge and discharge. This may cause a reduction in battery capacity. In addition, when the battery ruptures due to a reaction gas generated by a side reaction between metallic lithium and the electrolytic solution, there is a safety concern that moisture in the air reacts with metallic lithium to generate hydrogen. Patent Document 1 exemplifies graphite that occludes and releases lithium as a negative electrode active material. Graphite is a material widely used as a negative electrode active material for lithium ion secondary batteries.

Japanese Patent No. 5652029

  In recent years, the development of a battery including a positive electrode using an organic compound as an active material for in-vehicle use has been promoted due to environmental problems and increased interest in higher performance non-aqueous electrolyte secondary batteries. Among these, batteries having higher durability in addition to high output characteristics are demanded.

  An object of the present invention is to improve a safety problem which is a concern when metallic lithium is used as a negative electrode active material in a battery including a positive electrode using an organic compound as an active material, and to obtain high output characteristics. A negative electrode and a battery using the negative electrode.

  As a result of intensive studies, the inventor has found that the above problem can be solved by using a specific non-graphitizable carbonaceous material for a negative electrode for a battery including a positive electrode using an organic compound as an active material. The invention has been completed.

That is, the present invention includes the following preferred embodiments.
[1] A negative electrode containing a non-graphitizable carbonaceous material, which is a chemistry using lithium chloride as a reference substance observed by ⁷ Li nucleus-solid NMR analysis of the non-graphitizable carbonaceous material when fully charged. A negative electrode for a battery comprising a positive electrode using an organic compound as an active material, wherein a main resonance peak position of a shift value is greater than 115 ppm.
[2] The average plane distance d ₀₀₂ of the (002) plane calculated using the Bragg equation by the wide-angle X-ray diffraction method of the non-graphitizable carbonaceous material is in the range of 0.36 to 0.42 nm. ] The negative electrode as described in].
[3] The negative electrode according to [1] or [2], wherein the non-graphitizable carbonaceous material is derived from a plant-derived carbon precursor.
[4] The negative electrode according to any one of [1] to [3], wherein the potassium element content is 0.1% by mass or less and the iron element content is 0.02% by mass or less.
[5] A battery comprising a negative electrode according to any one of [1] to [4], the cathode comprising an organic compound as an active material.

  When used for a negative electrode for a battery comprising a positive electrode comprising the organic compound of the present invention as an active material, a battery having very high output characteristics and durability can be obtained.

⁷ shows a ⁷ Li nucleus-solid NMR diagram of a non-graphitizable carbonaceous material prepared according to Example 4. FIG. ⁷ Li nucleus carbonaceous material prepared according to Comparative Example 1 - a solid state NMR view.

<Battery negative electrode comprising a positive electrode comprising an organic compound as an active material>
A negative electrode for a battery comprising a positive electrode comprising the organic compound of the present invention as an active material, and a battery using the negative electrode comprise a non-graphitizable carbonaceous material, and the negative electrode comprising the non-graphitizable carbonaceous material comprises When fully charged, the main resonance peak position of the chemical shift value based on lithium chloride observed by ⁷ Li nucleus-solid NMR analysis is greater than 115 ppm. That is, when the negative electrode for a battery comprising a positive electrode using the organic compound of the present invention as an active material is doped with lithium until it is in a fully charged state, in the spectrum observed by ⁷ Li nucleus-solid NMR analysis, The main resonance peak is at a position shifted more than 115 ppm on the low magnetic field side with respect to the resonance peak of lithium chloride.

In this specification, “fully charged” or “fully charged state” means that a non-aqueous electrolyte secondary battery is assembled using a negative electrode containing a non-graphitizable carbonaceous material and a counter electrode containing lithium, and metallic lithium It means that lithium is charged (doped) to the negative electrode until just before the precipitation is confirmed by ⁷ Li nucleus-solid NMR analysis, or the state of being charged as such. Usually, a fully charged state is obtained by charging to a range of 580 to 700 mAh / g, preferably 580 to 680 mAh / g, more preferably 580 to 660 mAh / g per unit mass of the negative electrode active material at a constant current value.

  The negative electrode in the present invention is used for a battery including a positive electrode using an organic compound as an active material. Since the non-aqueous electrolyte secondary battery assembled using the negative electrode of the present invention and the positive electrode comprising lithium has very high output characteristics and durability, the negative electrode of the present invention is particularly suitable as the negative electrode for the battery. Is suitable.

<Main resonance peak position of chemical shift value (non-graphitizable carbonaceous material)>
The non-graphitizable carbonaceous material contained in the negative electrode of the present invention is based on lithium chloride observed when lithium is charged (dope) until full charge and ⁷ Li nucleus-solid state NMR analysis is performed. The main resonance peak position of the chemical shift value is greater than 115 ppm, preferably greater than 118 ppm, more preferably greater than 120 ppm. Further, the main resonance peak position of the chemical shift value is usually 148 ppm or less, preferably 146 ppm or less, more preferably 144 ppm or less, and further preferably 142 ppm or less.

  The main resonance peak position of the chemical shift value based on lithium chloride is larger than 115 ppm, that is, the above main resonance peak position is observed from 115 ppm on the low magnetic field side, indicating that the non-graphitizable carbonaceous material contained in the negative electrode The amount of occlusion of clustered lithium in the material is large, that is, the amount of clustered lithium that reversibly contributes to charge / discharge is large, and the amount of lithium ions lost due to irreversible side reactions during charge / discharge is small. means. The small amount of lithium ions that are hardly generated and lost due to the side reaction means that the increase in the internal resistance of the battery due to the side reaction product is suppressed, and as a result, the internal resistance of the battery is maintained at a low level. High output characteristics can be obtained with this battery. Further, by suppressing side reactions, local charge / discharge on the negative electrode and dendrite-like lithium deposition are suppressed, which contributes to improving the durability of the battery.

  The amount of clustered lithium is large, that is, there is little loss of lithium in the negative electrode due to side reactions during charging / discharging, etc., and it is necessary to supplement the negative electrode with lithium by using an excessive positive electrode containing metallic lithium and lithium ions during pre-doping This is advantageous in terms of cost.

  When a carbonaceous material having a main resonance peak position of a chemical shift value based on lithium chloride of 115 ppm or less is used, since the amount of clustered lithium is small, a large number of side reactions occur during charging and discharging. In a battery including a positive electrode using the organic compound of the present invention as an active material, it is extremely difficult to obtain a battery having high output characteristics and high durability.

In order to adjust the main resonance peak position to a value within the above range, for example, a material containing a carbon precursor from which impurities have been removed by vapor phase deashing or liquid phase deashing is used as an inert gas at 1050 ° C. to 1400 ° C. The use of a non-graphitizable carbonaceous material produced by firing in an atmosphere for the negative electrode can be mentioned. Details of the ⁷ Li nucleus-solid NMR analysis are as described in the examples.

<Expansion coefficient of electrode>
The expansion coefficient in the fully charged state of the negative electrode containing the non-graphitizable carbonaceous material of the present invention is preferably 107% or less based on the thickness of the negative electrode before charging. When the expansion coefficient exceeds 107%, contact failure between the active materials occurs in the electrode, and the electrode resistance becomes high. Therefore, a non-aqueous electrolyte secondary battery having good output characteristics (high discharge capacity retention rate) is obtained. There may not be.
The expansion coefficient is more preferably 106% or less, and particularly preferably 105% or less. When the expansion coefficient is less than or equal to the above upper limit value, it is easy to ensure good conduction paths and lithium ion diffusion between the active materials (non-graphitizable carbonaceous materials) in the electrode, so that low electrode resistance is easily obtained and good Easy output characteristics.

  In order to adjust the electrode expansion coefficient to the above value or less, for example, in an inert gas atmosphere at 1050 ° C. to 1400 ° C. while actively removing pyrolysis gas such as carbon monoxide and hydrogen from a material containing carbon. It is mentioned to use the non-graphitizable carbonaceous material produced by baking with a negative electrode. In the negative electrode comprising the non-graphitizable carbonaceous material manufactured by the above method, many lithium ions are charged not only between the carbon crystal layers but also in the gaps between the carbon crystals, so that the lithium ions are charged only between the carbon crystal layers. It is thought that the electrode expansion coefficient is significantly smaller than the conventional negative electrode.

<Average surface distance _d002 >
The non-graphitizable carbonaceous material used for the negative electrode for a battery comprising the positive electrode using the organic compound of the present invention as the active material is an average surface of (002) planes calculated using the Bragg equation by the wide angle X-ray diffraction method. The distance d ₀₀₂ is preferably 0.36 nm to 0.42 nm, more preferably 0.37 nm to 0.40 nm, and particularly preferably 0.38 nm to 0.39 nm. When the average plane distance d ₀₀₂ of the (002) plane is within the above range, the output as a battery due to an increase in resistance when lithium ions are inserted into the carbonaceous material or an increase in output resistance. It is easy to suppress deterioration of characteristics. In addition, a decrease in battery durability due to repeated expansion and contraction of the non-graphitizable carbonaceous material is easily suppressed. In order to adjust the average spacing to the above range, for example, the firing temperature of the carbon precursor that gives the non-graphitizable carbonaceous material may be in the range of 1050 to 1400 ° C. Moreover, the method of baking by mixing with thermally decomposable resin, such as a polystyrene, and the method of giving CVD processing, such as hydrocarbon gas, to the non-graphitizable carbonaceous material baked at 1050-1400 degreeC can also be used. Here, the details of the measurement of the average surface distance _d002 are as described in the examples.

<Plant-derived carbon precursor>
The non-graphitizable carbonaceous material used for the negative electrode for a battery comprising a positive electrode using the organic compound of the present invention as an active material is preferably derived from a plant-derived carbon precursor. In the present invention, “plant-derived carbon precursor” means a plant-derived material before carbonization, or a plant-derived material after carbonization (char derived from plants). The plant as a raw material (hereinafter sometimes referred to as “plant raw material”) is not particularly limited. Examples include coconut shells, peas, tea leaves, sugar cane, fruits (eg, tangerines, bananas), cocoons, rice husks, hardwoods, conifers, and bamboo. Examples of this include waste (e.g. used tea leaves) after subjecting it to its intended use, or part of a plant material (e.g. banana or tangerine peel). These plants can be used alone or in combination of two or more. Among these plants, coconut shells that are easily available in large quantities are preferred.

  The coconut shell is not particularly limited. For example, palm coconut (coconut palm), coconut palm, salak or coconut palm can be mentioned. These coconut shells can be used alone or in combination. Coconut palm and palm palm coconut shells, which are biomass wastes that are used as foods, detergent raw materials, biodiesel oil raw materials and the like and are generated in large quantities, are particularly preferable.

  The method for carbonizing the plant material, that is, the method for producing the plant-derived char is not particularly limited. For example, it is performed by heat-treating the plant material in an inert gas atmosphere of 300 ° C. or higher (hereinafter sometimes referred to as “temporary firing”).

  It can also be obtained in the form of char (eg, coconut shell char).

  By using a carbon precursor having moderately fine voids of plant origin as a raw material for a non-graphitizable carbonaceous material used for a negative electrode for a battery comprising a positive electrode using the organic compound of the present invention as an active material, Micropores capable of occluding a large amount of clustered lithium are formed inside the carbonaceous carbonaceous material. The electrode containing the non-graphitizable carbonaceous material of the present invention has a coefficient of expansion due to the fact that many micropores of the non-graphitizable carbonaceous material partially absorb the volume change of the electrode active material accompanying charge / discharge. It is thought that it can contribute to lowering.

<Oxygen element content>
The lower the oxygen element content of the non-graphitizable carbonaceous material used for the negative electrode for batteries comprising the positive electrode using the organic compound of the present invention as the active material, the better. The analytical value obtained by elemental analysis is preferably 1% by mass or less, more preferably 0.8% by mass or less, still more preferably 0.5% by mass or less, and most preferably 0.3% by mass or less. When the oxygen element content is less than the above value, the lithium ion is consumed due to the side reaction between lithium ions and oxygen, resulting in a decrease in utilization efficiency of the lithium ions, and the reaction produced by the side reaction between the lithium ions and oxygen. Increase in battery internal resistance due to materials, oxygen attracts moisture in the air and water is not absorbed and easily desorbed, and lithium ion utilization efficiency decreases, and gas generation in the electrode due to moisture-induced side reactions , Is easily suppressed.

  A method for adjusting the oxygen element content to the above value or less is not limited. For example, an oxygen element content can be adjusted to the above value or less by firing a carbon precursor of plant origin at a predetermined temperature and then firing it in an inert gas atmosphere at a temperature of 1050 ° C. to 1400 ° C. .

<True density ρ _Bt >
The non-graphitizable carbonaceous material used for the negative electrode for a battery comprising the positive electrode comprising the organic compound of the present invention as an active material has a true density ρ _Bt by the butanol method from the viewpoint of increasing the capacity per mass in the battery. is preferably 1.40~1.70g / cm ^3, more preferably 1.42~1.65g / cm ^3, particularly preferably 1.44~1.60g / cm ^3. The true density in the above range can be obtained, for example, by setting the firing process temperature when producing a non-graphitizable carbonaceous material from plant raw materials to 1050 to 1400 ° C.

<Potassium element content and iron element content>
The potassium element content of the non-graphitizable carbonaceous material used for the negative electrode for batteries comprising the positive electrode comprising the organic compound of the present invention as the active material is from the viewpoint of suppressing side reactions between impurities containing potassium and the electrolytic solution. The content is preferably 0.1% by mass or less, more preferably 0.05% by mass or less, and further preferably 0.03% by mass or less. It is particularly preferred that the non-graphitizable carbonaceous material contains substantially no potassium element. In addition, the iron element content of the non-graphitizable carbonaceous material used in the negative electrode for a battery including the positive electrode using the organic compound of the present invention as an active material is a viewpoint that suppresses a side reaction between an impurity containing iron and an electrolytic solution. Therefore, it is preferably 0.02% by mass or less, more preferably 0.015% by mass or less, and still more preferably 0.01% by mass or less. It is particularly preferable that the non-graphitizable carbonaceous material contains substantially no iron element. Here, the phrase “substantially containing no potassium element or iron element” means that the potassium element content or the iron element content is determined by the fluorescent X-ray analysis described later (for example, analysis using “LAB CENTER XRF-1700” manufactured by Shimadzu Corporation). It means that it is below the detection limit value. When the potassium element content and the iron element content are not more than the above values, sufficiently high output characteristics are easily obtained in the battery of the present invention using the non-graphitizable carbonaceous material. Furthermore, problems of durability and safety of the battery due to short-circuiting when these metal elements are eluted and re-deposited in the electrolytic solution are easily avoided. Details of the measurement of the potassium element content and the iron element content are as described in the examples.

<Moisture absorption>
The moisture absorption of the non-graphitizable carbonaceous material used for the negative electrode for a battery comprising the positive electrode comprising the organic compound of the present invention as an active material is preferably 50000 ppm or less, more preferably 30000 ppm or less, and particularly preferably 10000 ppm or less. . The smaller the amount of moisture absorption, the smaller the moisture adsorbed on the non-graphitizable carbonaceous material, and the more preferable it is because the generation of gas in the electrode due to moisture-induced side reactions is easily suppressed. The moisture absorption amount of the non-graphitizable carbonaceous material can be reduced, for example, by reducing the amount of oxygen atoms contained in the non-graphitizable carbonaceous material. The moisture absorption of the non-graphitizable carbonaceous material is measured using, for example, a Karl Fischer.

<Specific surface area>
The non-graphitizable carbonaceous material used for the negative electrode for batteries comprising the positive electrode using the organic compound of the present invention as the active material has a specific surface area determined by the nitrogen adsorption BET three-point method of 1 to 100 m ² / g. it is preferred, more preferably 2~80m ² / g, particularly preferably 3~60m ² / g. When the specific surface area is within the above range, in a battery produced using a non-graphitizable carbonaceous material, lithium ions are hardly graphitized carbon while suppressing an excessive side reaction between the electrolyte and the non-graphitizable carbonaceous material. Since it is easy to dope into the carbonaceous material and the contact area for dedoping lithium ions from the non-graphitizable carbonaceous material is easy to be maintained, high output characteristics can be obtained. The specific surface area can be adjusted, for example, by controlling the temperature of the decalcification process.

<Method for producing non-graphitizable carbonaceous material>
A method for producing a non-graphitizable carbonaceous material used for a negative electrode for a battery comprising a positive electrode comprising the organic compound of the present invention as an active material includes a step of acid-treating a plant-derived carbon precursor, and an acid-treated carbon precursor A step of firing the body in an inert gas atmosphere at 1050 ° C to 1400 ° C.

<Plant-derived carbon precursor>
The “plant-derived carbon precursor” means a plant-derived material before carbonization or a plant-derived material after carbonization (char derived from plants) as described above. The plant (plant raw material) used as a raw material is not specifically limited. Plants as exemplified above can be used alone or in combination of two or more. Among these, coconut shells that can be easily obtained in large quantities are preferable.

  The coconut shell is not particularly limited. The coconut shells as exemplified above can be used alone or in combination. Coconut palm and palm palm coconut shells, which are used as foods, detergent raw materials, biodiesel oil raw materials and the like and are biomass wastes generated in large quantities, are particularly preferable.

  The method for carbonizing the plant material, that is, the method for producing the plant-derived char is not particularly limited. For example, it is performed by calcining a plant material in an inert gas atmosphere at 300 ° C. or higher.

  It can also be obtained in the form of char (eg, coconut shell char).

  Generally, plant raw materials include alkali metal elements (eg, potassium and sodium), alkaline earth metal elements (eg, magnesium and calcium), transition metal elements (eg, iron and copper), and non-metallic elements (eg, phosphorus). Contains a lot. When such a non-graphitizable carbonaceous material containing a large amount of metallic elements and nonmetallic elements is used as the negative electrode, the electrochemical characteristics, durability, and safety of the battery including the positive electrode using an organic compound as an active material May be adversely affected.

<Acid treatment>
Therefore, the method for producing a non-graphitizable carbonaceous material used for a negative electrode for a battery comprising a positive electrode using the organic compound of the present invention as an active material includes a step of acid-treating a plant-derived carbon precursor. Here, reducing the content of the metal element and / or the non-metal element in the carbon precursor by acid treatment of the plant-derived carbon precursor is hereinafter also referred to as decalcification.

  The acid treatment method, that is, the decalcification method is not particularly limited. For example, a method of extracting and demineralizing metal using acidic water containing mineral acid such as hydrochloric acid or sulfuric acid, organic acid such as acetic acid or formic acid (liquid phase demineralization), high temperature containing halogen compounds such as hydrogen chloride A method of deashing by exposing to a gas phase (vapor phase deashing) can be used.

<Liquid phase demineralization>
For liquid phase decalcification, plant-derived carbon precursors are immersed in an organic acid aqueous solution, and alkali metal elements, alkaline earth metal elements and / or non-metal elements are eluted from the plant-derived carbon precursors and removed. It is preferable to do.

  When carbonaceous plant-derived carbon precursors containing these metal elements are carbonized, carbon necessary for carbonization may be decomposed. Further, since non-metallic elements such as phosphorus are easily oxidized, the degree of oxidation on the surface of the carbide changes and the properties of the carbide change greatly, which is not preferable. Furthermore, when liquid phase decalcification is performed after carbonizing the carbon precursor, phosphorus, calcium and magnesium may not be sufficiently removed. Further, depending on the content of the metal element and / or non-metal element in the carbide, the liquid-phase deashing time and the remaining amount of the metal element and / or non-metal element in the carbide after the liquid-phase deashing vary greatly. Therefore, it is preferable that the content of the metal element and / or non-metal element in the carbon precursor is sufficiently removed before carbonization. That is, in liquid phase decalcification, it is preferable to use a plant-derived material before carbonization as a “plant precursor carbon precursor”.

  It is preferable that the organic acid used in the liquid phase decalcification does not contain an element serving as an impurity source such as phosphorus, sulfur and halogen. When the organic acid does not contain elements such as phosphorus, sulfur and halogen, it is suitable as a carbon material even if the water precursor after liquid phase decalcification is omitted and the carbon precursor in which the organic acid remains is carbonized. This is advantageous because a carbide that can be used for the above is obtained. Further, it is advantageous because the waste liquid treatment of the organic acid after use can be performed relatively easily without using a special apparatus.

  Examples of organic acids include saturated carboxylic acids such as formic acid, acetic acid, propionic acid, oxalic acid, tartaric acid and citric acid, unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid and fumaric acid Carboxylic acids such as benzoic acid, phthalic acid and naphthoic acid. Acetic acid, oxalic acid and citric acid are preferred from the viewpoint of availability, corrosion due to acidity, and influence on human body.

  In the present invention, the organic acid is mixed with an aqueous solution and used as an organic acid aqueous solution from the viewpoints of solubility of the eluted metal compound, waste disposal, environmental compatibility, and the like. Examples of the aqueous solution include water and a mixture of water and a water-soluble organic solvent. Examples of the water-soluble organic solvent include alcohols such as methanol, ethanol, propylene glycol, and ethylene glycol.

  The concentration of the acid in the organic acid aqueous solution is not particularly limited. The concentration can be adjusted according to the type of acid used. In the present invention, usually 0.001% to 20% by mass, more preferably 0.01% to 18% by mass, and particularly preferably 0.02% to 15% by mass based on the total amount of the organic acid aqueous solution. An organic acid aqueous solution having an acid concentration in the range is used. If the acid concentration is within the above range, an appropriate metal element and / or nonmetal element elution rate can be obtained, so that liquid phase deashing can be performed in a practical time. Moreover, since the residual amount of acid in the carbon precursor is reduced, the influence on the subsequent product is also reduced.

  The pH of the organic acid aqueous solution is preferably 3.5 or less, more preferably 3 or less. When the pH of the aqueous organic acid solution is not more than the above value, the removal of the metallic element and / or the nonmetallic element is efficiently performed without decreasing the dissolution rate of the metallic element and / or the nonmetallic element in the aqueous organic acid solution. Easy to be done.

  The temperature of the organic acid aqueous solution when dipping the carbon precursor is not particularly limited. Preferably it is 45 to 120 ° C, more preferably 50 to 110 ° C, particularly preferably 60 to 100 ° C. If the temperature of the organic acid aqueous solution at the time of immersing the carbon precursor is within the above range, the decomposition of the acid to be used is suppressed, and the liquid element deashing can be performed in a practical time. It is preferable because the elution rate is easily obtained. Moreover, it is preferable because liquid phase demineralization can be easily performed without using a special apparatus.

  The time for immersing the carbon precursor in the organic acid aqueous solution can be appropriately adjusted according to the acid used. In the present invention, the immersion time is usually in the range of 1 to 100 hours, preferably 2 to 80 hours, more preferably 2.5 to 50 hours, from the viewpoint of economy and decalcification efficiency.

  The ratio of the mass of the carbon precursor to be immersed with respect to the mass of the organic acid aqueous solution can be appropriately adjusted according to the type, concentration and temperature of the organic acid aqueous solution to be used, and is usually 0.1% by mass to 200% by mass. The range is preferably 1% by mass to 150% by mass, and more preferably 1.5% by mass to 120% by mass. If it is in the said range, since the metal element and / or nonmetallic element which were eluted to organic acid aqueous solution are hard to precipitate from organic acid aqueous solution, and reattachment to a carbon precursor is easy to be suppressed, it is preferable. Moreover, if it is in the said range, since volume efficiency becomes appropriate, it is preferable from an economical viewpoint.

  It does not specifically limit as atmosphere which performs liquid phase demineralization, According to the method used for immersion, you may differ. In the present invention, liquid phase demineralization is usually performed in an air atmosphere.

  These operations may be repeated preferably 1 to 8 times, more preferably 2 to 5 times.

  In this invention, you may perform a washing | cleaning process and / or a drying process as needed after liquid phase demineralization.

<Gas phase demineralization>
As the vapor phase decalcification, it is preferable to heat-treat the plant-derived carbon precursor in a vapor phase containing a halogen compound. In vapor phase deashing, if a pyrogenic reaction of a plant-derived carbon precursor is accompanied during heat treatment, the efficiency of vapor phase demineralization is reduced due to the generation of pyrolysis components, and the heat treatment components cause the inside of the heat treatment apparatus to Contaminated and may interfere with stable operation. From these viewpoints, it is preferable to use a plant-derived material after carbonization as the “plant-derived carbon precursor”.

  The halogen compound used in the gas phase deashing is not particularly limited. For example, fluorine, chlorine, bromine, iodine, hydrogen fluoride, hydrogen chloride, hydrogen bromide, iodine bromide, chlorine fluoride (ClF), iodine chloride (ICl), iodine bromide (IBr), bromine chloride (BrCl) And mixtures thereof can be used. A compound that generates these halogen compounds by thermal decomposition, or a mixture thereof can also be used. From the viewpoint of supply stability and stability of the halogen compound used, it is preferable to use hydrogen chloride.

  In vapor phase deashing, a halogen compound and an inert gas may be mixed and used. An inert gas will not be specifically limited if it is a gas which does not react with the carbon component which comprises the carbon precursor of plant origin. For example, nitrogen, helium, argon, krypton, or a mixed gas thereof can be used. From the viewpoint of supply stability and economy, it is preferable to use nitrogen.

  In the gas phase deashing, the mixing ratio of the halogen compound and the inert gas is not limited as long as sufficient deashing can be achieved. For example, from the viewpoint of safety, economy, and persistence in the carbon precursor, the amount of the halogen compound with respect to the inert gas is preferably 0.01 to 10.0% by volume, more preferably 0.05. It is -8.0 volume%, Most preferably, it is 0.1-5.0 volume%.

  The temperature of the vapor phase demineralization may vary depending on the plant-derived carbon precursor to be demineralized, but from the viewpoint of easily obtaining the desired oxygen element content and specific surface area, for example, 500 to 950 ° C., preferably Is 600 to 940 ° C, more preferably 650 to 940 ° C, and particularly preferably 850 to 930 ° C. When the deashing temperature is within the above range, good deashing efficiency is obtained, and the deashing is easily performed sufficiently, and activation by the halogen compound is easily avoided.

  The time for vapor phase demineralization is not particularly limited. From the viewpoint of the economic efficiency of the reaction equipment and the carbon structure retention, it is, for example, 5 to 300 minutes, preferably 10 to 200 minutes, more preferably 20 to 150 minutes.

  The particle diameter of the plant-derived carbon precursor to be subjected to vapor phase demineralization is not particularly limited. If the particle size is too small, it may be difficult to separate the gas phase containing the removed potassium and the carbon precursor of plant origin, so the lower limit of the average particle size (average particle size) is 100 μm or more is preferable, 300 μm or more is more preferable, and 500 μm or more is particularly preferable. Further, the upper limit of the average value of the particle diameter (average particle diameter) is preferably 10,000 μm or less, more preferably 8000 μm or less, and particularly preferably 5000 μm or less from the viewpoint of fluidity in the mixed gas stream. Here, the details of the measurement of the average particle diameter are as described in the examples.

  The apparatus used for vapor phase demineralization is not particularly limited as long as it can be heated while mixing a carbon precursor derived from a plant and a vapor phase containing a halogen compound. For example, using a fluidized furnace, a continuous or batch type in-bed flow system using a fluidized bed or the like can be used. The supply amount (flow amount) of the gas phase is not particularly limited. From the viewpoint of fluidity in a mixed gas stream, for example, a gas phase of preferably 1 mL / min or more, more preferably 5 mL / min or more, particularly preferably 10 mL / min or more is supplied per 1 g of the carbon precursor of plant origin.

  In vapor phase deashing, after heat treatment in an inert gas atmosphere containing a halogen compound (hereinafter sometimes referred to as “halogen heat treatment”), further heat treatment in the absence of a halogen compound (hereinafter referred to as “vapor phase”). It is preferable to perform “deoxidation treatment”. Since halogen is contained in the plant-derived carbon precursor by the halogen heat treatment, it is preferable to remove the halogen contained in the plant-derived carbon precursor by gas phase deoxidation treatment. Specifically, the gas phase deoxidation treatment is usually performed at 500 ° C. to 940 ° C., preferably 600 to 940 ° C., more preferably 650 to 940 ° C., and particularly preferably 850 in an inert gas atmosphere containing no halogen compound. The heat treatment is performed at ˜930 ° C. The temperature of this heat treatment is preferably the same as or higher than the temperature of the preceding halogen heat treatment. For example, after the halogen heat treatment, the vapor phase deoxidation treatment can be performed by performing the heat treatment while shutting off the supply of the halogen compound. Further, the time for the vapor phase deoxidation treatment is not particularly limited. It is preferably 5 minutes to 300 minutes, more preferably 10 minutes to 200 minutes, and particularly preferably 10 minutes to 100 minutes.

  The acid treatment in the present invention is to remove (decalcify) potassium and / or iron contained in the plant-derived carbon precursor. The potassium element content contained in the plant-derived carbon precursor obtained after the acid treatment is preferably reduced to 0.1% by mass or less, more preferably 0.05% by mass or less, and further preferably 0.03% by mass or less. The Particularly preferably, the potassium element content is reduced to such an extent that the hardly graphitized carbonaceous material does not substantially contain. Further, the content of iron element contained in the carbon precursor obtained after the acid treatment is preferably 0.02% by mass or less, more preferably 0.015% by mass or less, and further preferably 0.01% by mass or less. . Particularly preferably, the iron element content is reduced to such an extent that the hardly graphitized carbonaceous material does not substantially contain. Here, the phrase “substantially containing no potassium element or iron element” means that the potassium element content or the iron element content is determined by the fluorescent X-ray analysis described later (for example, analysis using “LAB CENTER XRF-1700” manufactured by Shimadzu Corporation). It means that it is below the detection limit value. When the potassium element content and the iron element content are not more than the above values, as described above, sufficient output characteristics are easily obtained, and there is a problem of safety of a battery including a positive electrode using an organic compound as an active material. Easy to avoid. Details of the measurement of the potassium element content and the iron element content are as described in the examples.

  In the acid treatment in the present invention, a part of the carbon component is removed simultaneously with deashing. Specifically, in the case of liquid phase deashing, a part of the carbon component is removed by elution, and in the case of gas phase deashing, a part of the carbon component is removed by chlorine activation. This removed portion provides an occlusion point for clustered lithium after the firing step described below.

  In the present invention, the acid treatment is performed at least once. The acid treatment may be performed twice or more using the same or different acids.

  The plant-derived carbon precursor that is the subject of acid treatment is a plant-derived material before carbonization or a plant-derived material after carbonization, but when acid treatment is performed by liquid phase decalcification, an increase in elution of carbon components, That is, from the viewpoint of increasing the lithium occlusion point, it is preferable to perform liquid phase decalcification on the plant raw material itself before carbonization.

  If the carbon precursor after acid treatment is a carbon precursor that has not been subjected to carbonization treatment, that is, if it is a carbon precursor after acid treatment of the plant raw material before carbonization, then carbonization treatment is performed. . The carbonization method is not particularly limited as described above. For example, it is performed by pre-baking an acid-treated plant material before carbonization in an inert gas atmosphere of 300 ° C. or higher.

  Plant-derived carbon precursors are pulverized and classified as necessary, and the average particle size thereof is adjusted. The pulverization step and the classification step are preferably performed after the acid treatment.

<Crushing>
In the pulverization step, the plant-derived carbon precursor is preferably pulverized so that the average particle size after the calcination step is in the range of, for example, 1 to 30 μm, from the viewpoint of coatability during electrode production. That is, the average particle diameter (Dv ₅₀ ) of the non-graphitizable carbonaceous material of the present invention is adjusted to be in the range of 1 to 30 μm, for example. When the average particle diameter of the non-graphitizable carbonaceous material is 1 μm or more, the amount of fine powder is suppressed and side reactivity with the electrolyte is difficult to occur, and the internal resistance of the battery is increased due to deposition of reaction products on the negative electrode Is easily suppressed. In addition, when a negative electrode is produced using the obtained non-graphitizable carbonaceous material, it is easy to ensure sufficient gaps formed between the carbonaceous materials, and good migration of lithium ions in the electrolyte is ensured. Cheap. The average particle diameter (Dv ₅₀ ) of the carbonaceous material of the present invention is preferably 1 μm or more, more preferably 1.5 μm or more, and particularly preferably 2 μm or more. On the other hand, it is preferable that the average particle diameter is 30 μm or less because the diffusion free process of lithium ions in the particles is small and rapid charge / discharge is likely to be possible. In order to improve output characteristics, it is effective to increase the electrode area. Therefore, it is effective to reduce the thickness of the active material applied to the current collector plate during electrode preparation. In order to reduce the coating thickness, it is preferable that the particle diameter of the active material is small. From such a viewpoint, the average particle size is preferably 30 μm or less, more preferably 19 μm or less, still more preferably 17 μm or less, still more preferably 16 μm or less, and particularly preferably 15 μm or less.

  In addition, the carbon precursor of plant origin contracts by about 0 to 20% depending on the conditions of the main firing described later. Therefore, in order for the average particle diameter after firing to be 1 to 30 μm, the average particle diameter of the plant-derived carbon precursor is 0 to 20% larger than the desired average particle diameter after firing. It is preferable to adjust so that it may become a diameter. Therefore, the average particle size after pulverization is preferably 1 to 36 μm, more preferably 1 to 22.8 μm, still more preferably 1 to 20.4 μm, still more preferably 1 to 19.2 μm, and particularly preferably 1 to 18 μm. It is preferable to perform pulverization.

  Since the carbon precursor does not dissolve even when the firing step described later is performed, the order of the pulverization step is not particularly limited. In view of the recovery rate (yield) of the carbon precursor in the acid treatment, it is preferable to carry out after the acid treatment, and from the viewpoint of sufficiently reducing the specific surface area of the carbonaceous material, it may be carried out before the firing step. preferable. However, it is not excluded to perform the pulverization step before the acid treatment or after the baking step.

  The crusher used for a crushing process is not specifically limited. For example, a jet mill, a ball mill, a hammer mill, a bead mill or a rod mill can be used. From the viewpoint of generating less fine powder, a jet mill having a classification function is preferable. When using a ball mill, a hammer mill, a bead mill, a rod mill or the like, fine powder can be removed by classification after the pulverization step.

<Classification>
By the classification step, the average particle diameter of the carbonaceous material can be adjusted more accurately. For example, particles having a particle diameter of less than 1 μm can be removed.

  When particles having a particle diameter of less than 1 μm are removed by classification, it is preferable that the content of particles having a particle diameter of less than 1 μm is 3% by volume or less in the non-graphitizable carbonaceous material used in the negative electrode for a battery of the present invention. . The removal of particles having a particle diameter of less than 1 μm is not particularly limited as long as it is performed after pulverization, but it is preferably performed simultaneously with classification in pulverization. In the non-graphitizable carbonaceous material used in the battery negative electrode of the present invention, the content of particles having a particle diameter of less than 1 μm suppresses side reactions between the electrolyte and the non-graphitizable carbonaceous material, and increases the internal resistance of the battery. From the viewpoint of suppression, it is preferably 3% by volume or less, more preferably 2.5% by volume or less, and particularly preferably 2.0% by volume or less.

  The classification method is not particularly limited. Examples include classification using a sieve, wet classification, or dry classification. Examples of the wet classifier include a classifier using a principle such as gravity classification, inertia classification, hydraulic classification, or centrifugal classification. Examples of the dry classifier include a classifier using a principle such as sedimentation classification, mechanical classification, or centrifugal classification.

  The pulverization step and the classification step can be performed using one apparatus. For example, the pulverization step and the classification step can be performed using a jet mill having a dry classification function. Furthermore, an apparatus in which the pulverizer and the classifier are independent can be used. In this case, pulverization and classification can be performed continuously, but pulverization and classification can also be performed discontinuously.

<Baking>
After optionally pulverizing and classifying, the non-graphitizable carbonaceous material of the present invention can be produced by firing the carbon precursor that has been subjected to acid treatment and carbonization treatment. The firing step is a step of firing at a firing temperature after the temperature is raised from room temperature to a predetermined firing temperature. The carbon precursor may be calcined at (a) 1050 to 1400 ° C. (main calcining), or the carbon precursor is calcined at (b) less than 350 to 1050 ° C. (preliminary calcining), and then further 1050 After baking at 1400 ° C. (main baking) or (c) baking at 1050 to 1400 ° C. (main baking), heat treatment (CVD processing) at 500 to 1000 ° C. in an inert gas atmosphere containing a hydrocarbon compound. Good. Below, an example of the procedure of preliminary baking, main baking, and CVD processing is demonstrated in order.

<Pre-baking>
The pre-baking step in the method for producing a non-graphitizable carbonaceous material used for a negative electrode for a battery comprising a positive electrode using the organic compound of the present invention as an active material is, for example, a 350 carbon precursor subjected to acid treatment and carbonization treatment. It can carry out by baking at the temperature of less than -1100 degreeC. By removing volatile components (for example, CO ₂ , CO, CH _4, H _2, etc.) and tar components by pre-calcination, their generation in the main calcination can be reduced, and the burden on the calciner can be reduced. The pre-baking temperature is usually less than 350 to 1050 ° C, preferably less than 400 to 1050 ° C. Pre-baking can be performed according to a normal pre-baking procedure. Specifically, the preliminary firing can be performed in an inert gas atmosphere, and examples of the inert gas include nitrogen or argon. Pre-baking can also be performed under reduced pressure, for example, 10 KPa or less. The pre-baking time is not particularly limited, and is usually 0.5 to 10 hours, preferably 1 to 5 hours.

  In the case of pre-baking in the method for producing a non-graphitizable carbonaceous material used for a negative electrode for a battery comprising a positive electrode using the organic compound of the present invention as an active material, the tar to the carbon precursor is used in the pre-baking step. It is believed that component and hydrocarbon gas coverage occurs. This carbonaceous film is considered to favorably reduce the specific surface area of the non-graphitizable carbonaceous material.

<Main firing>
The main firing step in the method for producing a non-graphitizable carbonaceous material used for a negative electrode for a battery comprising a positive electrode using the organic compound of the present invention as an active material can be performed according to a normal main firing procedure. A non-graphitizable carbonaceous material is obtained later.

  The main firing temperature is usually from 1050 to 1400 ° C, preferably from 1100 to 1380 ° C, more preferably from 1150 to 1350 ° C. The main firing can be performed in an inert gas atmosphere, and examples of the inert gas include nitrogen and argon. In addition, the main baking can be performed in an inert gas containing a halogen gas. Furthermore, the main firing can be performed under reduced pressure, for example, at 10 KPa or less.

  The time for the main baking is not particularly limited, and is, for example, 0.05 to 10 hours, preferably 0.05 to 8 hours, and more preferably 0.05 to 6 hours.

  In the non-graphitizable carbonaceous material used for the negative electrode for a battery including the positive electrode using the organic compound of the present invention as an active material, when the carbon precursor is fired, it can be mixed with a volatile organic material and fired. The specific surface area of the non-graphitizable carbonaceous material obtained from the carbon precursor can be made more suitable for the negative electrode for a battery of the present invention by mixing with a volatile organic material and firing.

  When the carbon precursor is heat-treated in the main firing step, gases such as carbon monoxide and hydrogen are generated from the carbon precursor itself. These gases are highly reactive, and in order to destroy voids between carbon crystals that can occlude clustered lithium, it is important to control the reaction between the gas generated during the heat treatment and the carbon precursor. For example, in WO2017 / 022486, a non-graphitizable carbonaceous material that can occlude a larger amount of clustered lithium during charging is obtained by performing heat treatment after performing vapor phase decalcification or liquid phase demineralization. Although it is possible to obtain a carbonaceous material for a non-aqueous electrolyte secondary battery having high charge capacity and high charge / discharge efficiency by WO2017 / 022486, the present invention further positively removes pyrolysis gas during firing. Thus, it has been found that higher output characteristics can be obtained. The method of firing while actively removing the pyrolysis gas from the carbon precursor is not particularly limited. For example, the heat treatment is performed by increasing the supply amount of the inert gas during the firing, or the sample at the time of the firing is prepared. There is a method of positively removing the gas staying in the sample by reducing the stacking height. By these methods, it is possible to remove the reactive gas generated from the carbon precursor itself before reacting with the carbon precursor. Therefore, a non-graphitizable carbonaceous material having a more controlled carbon structure can be produced. The time for the main baking is not particularly limited, and is, for example, 0.05 to 10 hours, preferably 0.05 to 8 hours, and more preferably 0.05 to 6 hours.

<Volatile organic matter>
In the present invention, when the carbon precursor is fired, it can be fired by mixing with a volatile organic substance. The specific surface area of the non-graphitizable carbonaceous material obtained from the carbon precursor can be made more suitable for the negative electrode for a battery of the present invention by mixing with a volatile organic material and firing.

  Volatile organic substances that can be used in the method for producing a non-graphitizable carbonaceous material used for a negative electrode for a battery comprising a positive electrode comprising the organic compound of the present invention as an active material have a residual carbon ratio when incinerated at 800 ° C. Although it will not specifically limit if it is a volatile organic substance solid at normal temperature which is less than 5 mass% based on the mass of the volatile organic substance before ashing, the specific surface area of the non-graphitizable carbonaceous material produced from a carbon precursor Those that generate volatile substances that can be reduced (for example, hydrocarbon gases and tar components) are preferred. Although the content of the volatile substance capable of reducing the specific surface area in the volatile organic substance is not particularly limited, it is usually 1 to 20% by mass, preferably 3 to 15% by mass based on the mass of the volatile organic substance. %. In addition, in this specification, normal temperature refers to 25 degreeC.

  Examples of volatile organic substances include thermoplastic resins and low molecular organic compounds. More specifically, examples of the thermoplastic resin include polystyrene, polyethylene, polypropylene, poly (meth) acrylic acid or poly (meth) acrylic acid ester, and low molecular organic compounds include toluene, xylene, mesitylene, Examples thereof include styrene, naphthalene, phenanthrene, anthracene, and pyrene. In view of not volatilizing and oxidatively activating the surface of the carbon precursor when pyrolyzed at the firing temperature, the thermoplastic resin is preferably polystyrene, polyethylene or polypropylene, and the low molecular organic compound is naphthalene, phenanthrene, anthracene or pyrene. preferable. It is more preferable to use naphthalene, phenanthrene, anthracene or pyrene from the viewpoint of safety because of low volatility at room temperature.

The residual carbon ratio can be measured by quantifying the carbon content of the ignition residue after the sample is ignited in an inert gas. Ignition is about 1 g of volatile organic matter (this exact mass is W ₁ (g)) in a crucible and flowing 20 liters of nitrogen per minute at 10 ° C./min. It means that the temperature is raised to 800 ° C. and then held at 800 ° C. for 1 hour. Let the residue at this time be an ignition residue, and let the mass be W ₂ (g).

Next, the ignition residue is subjected to elemental analysis in accordance with the method defined in JIS M8819, and the carbon mass ratio P ₁ (%) is measured. The remaining coal rate P ₂ (%) is calculated by the following equation.

  When the carbon precursor and the volatile organic substance are mixed and fired, the carbon precursor and the volatile organic substance are preferably mixed at a mass ratio of 97: 3 to 40:60. This mixing ratio is more preferably 95: 5 to 60:40, particularly preferably 93: 7 to 80:20. By setting the mixing ratio within the above range, it is easy to sufficiently reduce the specific surface area of the non-graphitizable carbonaceous material. On the other hand, it is easy to avoid wasteful consumption of volatile organic substances due to saturation of the specific surface area reduction effect.

  Mixing of the carbon precursor and the volatile organic substance may be performed at any stage before or after the carbon precursor is pulverized. When mixing before pulverization of the carbon precursor, pulverization and mixing can be performed simultaneously by metering and supplying the carbon precursor and the volatile organic substance to the pulverizer. It is also preferable to mix a volatile organic substance after pulverization of the carbon precursor. The mixing method in this case may be any mixing method as long as both are uniformly mixed.

  The volatile organic substance is preferably mixed in the form of particles, but the particle shape and particle diameter are not particularly limited. From the viewpoint of uniformly dispersing in the pulverized carbon precursor, the average particle diameter of the volatile organic material is preferably 0.1 to 2000 μm, more preferably 1 to 1000 μm, and particularly preferably 2 to 600 μm.

  The mixture of the carbon precursor and the volatile organic material is used as long as the effect of the non-graphitizable carbonaceous material in the present invention is obtained, that is, as long as the specific surface area of the non-graphitizable carbonaceous material is reduced. And other components other than volatile organic substances. For example, natural graphite, artificial graphite, metal material, alloy material or oxide material may be included. The content of the other components is not particularly limited, and is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, with respect to 100 parts by mass of the mixture of the carbon precursor and the volatile organic substance. More preferably, it is 20 mass parts or less, Most preferably, it is 10 mass parts or less.

<CVD process>
In the non-graphitizable carbonaceous material used for the negative electrode for batteries comprising the positive electrode using the organic compound of the present invention as the active material, a CVD treatment using a hydrocarbon compound may be performed after the main firing step. The CVD process is a chemical vapor deposition (CVD) process that coats the non-graphitizable carbonaceous material obtained in the main firing step with a thermally decomposed hydrocarbon compound. The conditions for the CVD treatment are not particularly limited as long as the chemical vapor deposition is achieved. For example, the CVD treatment may be performed by a method of heat treatment at 500 to 1000 ° C. in an inert gas atmosphere containing a hydrocarbon compound. In the CVD treatment step, for example, the hydrocarbon compound is thermally decomposed by heat treatment at 500 to 1000 ° C., and the resulting pyrolyzed product is attached to the non-graphitizable carbonaceous material to cover the surface of the non-graphitizable carbonaceous material. As a result, the mechanism is not limited to the following mechanism, but the specific surface area can be reduced while maintaining the voids between the carbon crystals that can be occluded by the clustered lithium of the non-graphitizable carbonaceous material. It is thought that it can be suppressed. Therefore, it is considered that output characteristics can be improved. Moreover, when the functional group on the surface of the non-graphitizable carbonaceous material such as —OH group and —COOH group that can inhibit the occlusion of lithium ions reacts with the radical of the thermally decomposed hydrocarbon compound and is removed by the CVD process. Conceivable. For this reason, the oxygen element content in the carbonaceous material is reduced, and the irreversible side reaction during charging and discharging is suppressed, so that the output characteristics are considered to be improved.

  The hydrocarbon compound used in the CVD process is a compound mainly composed of carbon atoms and hydrogen atoms. Examples of the hydrocarbon compound include a low molecular organic hydrocarbon compound. In the CVD process, one type of hydrocarbon compound may be used, or two or more types of hydrocarbon compounds may be used in combination. The hydrocarbon compound mainly composed of carbon atoms and hydrogen atoms means that the total amount of carbon atoms and hydrogen atoms in the hydrocarbon compound is preferably 75% by mass or more based on the total mass of the hydrocarbon compound. Preferably it is 80 mass% or more, More preferably, it is 85 mass% or more.

  Examples of the low molecular organic hydrocarbon compound include hydrocarbon compounds having 1 to 20 carbon atoms. Carbon number of a hydrocarbon compound becomes like this. Preferably it is 2-18, More preferably, it is 3-16. The hydrocarbon compound may be a saturated hydrocarbon compound or an unsaturated hydrocarbon compound, and may be a chain hydrocarbon compound or a cyclic hydrocarbon compound. In the case of an unsaturated hydrocarbon compound, the unsaturated bond may be a double bond or a triple bond, and the number of unsaturated bonds contained in one molecule is not particularly limited. For example, the chain hydrocarbon compound is an aliphatic hydrocarbon compound, and can include a linear or branched alkane, alkene, or alkyne. Examples of the cyclic hydrocarbon compound include alicyclic hydrocarbon compounds (for example, cycloalkane, cycloalkene, cycloalkyne) and aromatic hydrocarbon compounds. Specifically, examples of the aliphatic hydrocarbon compound include methane, ethane, propane, butane, pentane, hexane, octane, nonane, decane, ethylene, propylene, butene, pentene, hexene, and acetylene. Examples of the alicyclic hydrocarbon compound include cyclopentane, cyclohexane, cycloheptane, cyclooctane, cyclononane, cyclopropane, cyclopentene, cyclohexene, cycloheptene, cyclooctene, decalin, norbornene, methylcyclohexane, and norbornadiene. Further, aromatic hydrocarbon compounds include benzene, toluene, xylene, mesitylene, cumene, butylbenzene, styrene, α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, vinylxylene, p- Examples thereof include monocyclic aromatic compounds such as tert-butylstyrene and ethylstyrene, and tricyclic to 6-ring condensed polycyclic aromatic compounds such as naphthalene, phenanthrene, anthracene, and pyrene, preferably condensed polycyclic aromatic compounds. A compound, more preferably naphthalene, phenanthrene, anthracene or pyrene. Here, the hydrocarbon compound may have an arbitrary substituent. The substituent is not particularly limited, and for example, an alkyl group having 1 to 4 carbon atoms (preferably an alkyl group having 1 to 2 carbon atoms) or an alkenyl group having 2 to 4 carbon atoms (preferably alkenyl having 2 carbon atoms). Group) and a cycloalkyl group having 3 to 8 carbon atoms (preferably a cycloalkyl group having 3 to 6 carbon atoms).

  In the CVD process, it is preferable to continuously supply the hydrocarbon compound in a gas state from the viewpoint of performing the CVD process uniformly and easily obtaining desired characteristics of the carbonaceous material. A hydrocarbon compound that is in a gaseous state at the temperature at which the CVD treatment is performed may be used, or a hydrocarbon compound that is in a gaseous state in the previous step of the CVD treatment may be supplied to the CVD treatment step. For example, using a hydrocarbon compound that is in a gaseous state at a temperature of 500 to 1000 ° C. and performing the CVD treatment by heat treatment at the temperature, the viewpoint of productivity and the mixing property between the hydrocarbon compound and the non-graphitizable carbonaceous material To preferred. From the above viewpoint, the boiling point of the hydrocarbon compound is preferably equal to or lower than the temperature at which the CVD treatment is performed.

  The CVD treatment step may be preferably performed in an inert gas atmosphere containing a hydrocarbon compound. Examples of the inert gas used in the CVD process include nitrogen and argon. The same inert gas may be used in the main baking step and the CVD treatment step, or different inert gases may be used. From the viewpoint of simplifying the manufacturing process and increasing the manufacturing efficiency, it is preferable to use the same inert gas in the main baking process and the CVD treatment process.

  When the CVD treatment step is performed in an inert gas atmosphere containing a hydrocarbon compound, the mixing ratio of the hydrocarbon compound and the inert gas is not particularly limited. For example, from the viewpoint of safety, economy, and contamination in the firing furnace, the amount of the hydrocarbon compound with respect to the inert gas is preferably 1 to 60% by volume, more preferably 5 to 50% by volume, Even more preferably, it is 10 to 45% by volume. According to the manufacturing method of this embodiment in which heat treatment is performed in an inert gas atmosphere containing a hydrocarbon compound, oxygen can be easily removed efficiently.

  The heat treatment temperature in the CVD treatment step may vary depending on the carbonaceous material, the type of hydrocarbon compound used, and the like, but from the viewpoint of obtaining a desired carbon structure, preferably 500 to 1000 ° C, more preferably 600 to 900 ° C, More preferably, it is 700-850 degreeC. If the heat treatment temperature is too low, the specific surface area can be sufficiently reduced and oxygen cannot be removed. On the other hand, if the heat treatment temperature becomes too high, a large number of hydrocarbon compound-derived carbon structures that do not contribute to the battery capacity adhere, and the battery capacity and output characteristics decrease.

  When the CVD treatment step is performed in an inert gas atmosphere containing a hydrocarbon compound, the supply amount of the inert gas stream containing the hydrocarbon compound is not particularly limited, but is preferably 0.1 L / min per 50 g of the carbonaceous material. As mentioned above, More preferably, it is 0.3 L / min or more, More preferably, it is 0.5 L / min or more. It is preferable to perform the heat treatment at a supply amount equal to or more than the above lower limit because carbon coating can be performed uniformly. The upper limit of the supply amount is preferably 10 L / min or less, more preferably 5 L / min or less. It is preferable to perform the heat treatment at a supply amount equal to or less than the above upper limit because the supplied hydrocarbon compound acts efficiently.

<Battery negative electrode comprising a positive electrode comprising an organic compound as an active material>
The negative electrode for a battery comprising a positive electrode using the organic compound of the present invention as an active material comprises a non-graphitizable carbonaceous material.

<Manufacture of negative electrode>
A negative electrode material used for a negative electrode for a battery comprising a positive electrode using the organic compound of the present invention as an active material is a binder (binder) added to a non-graphitizable carbonaceous material, an appropriate solvent is added in an appropriate amount, After kneading into an electrode mixture, the electrode mixture can be applied to a current collector plate made of a metal plate, etc., dried, and pressure molded. When the negative electrode has high conductivity, it is not always necessary to add a conductive aid. However, in order to impart higher conductivity, a conductive aid may be added when preparing the electrode mixture as necessary. it can.

  As the conductive assistant, conductive carbon black, vapor grown carbon fiber (VGCF), nanotube, or the like can be used. The addition amount of the conductive auxiliary agent varies depending on the type of conductive auxiliary agent to be used, but preferably 0.5 to 10% by mass (here, the amount of active material (non-graphitizable carbonaceous material) + the amount of binder + conductivity) Auxiliary agent amount = 100 mass%), more preferably 0.5-7 mass%, particularly preferably 0.5-5 mass%. By setting the addition amount of the conductive assistant within the above range, the expected conductivity can be easily obtained without deteriorating the dispersion of the conductive assistant in the electrode mixture.

  The binder to be added is not particularly limited as long as it does not react with the electrolytic solution. Examples thereof include PVDF (polyvinylidene fluoride), polytetrafluoroethylene, and a mixture of SBR (styrene butadiene rubber) and CMC (carboxymethyl cellulose). Among these, PVDF is preferable because PVDF attached to the surface of the active material hardly inhibits lithium ion migration and provides favorable input / output characteristics. The amount of the binder added varies depending on the type of the binder used, but in the case of a PVDF-based binder, it is preferably 3 to 13 based on the total mass of the non-graphitizable carbonaceous material, the binder and the conductive additive. It is mass%, More preferably, it is 3-10 mass%. By making the addition amount of the binder within the above range, the resistance of the obtained electrode is increased, the internal resistance of the battery is increased, the battery characteristics are deteriorated, or the negative electrode particles and the negative electrode particles and the current collector plate It is easy to avoid problems such as insufficient coupling.

  In order to dissolve PVDF to form a slurry, a polar solvent such as N-methylpyrrolidone (NMP) is preferably used as a solvent. In order to form an aqueous emulsion such as SBR or an aqueous solution such as CMC, water is preferably used as a solvent. In a binder that uses water as a solvent, a plurality of binders such as a mixture of SBR and CMC are often mixed and used. The addition amount of the solvent is preferably 0.5 to 5% by mass, more preferably 1 to 4% by mass, based on the total mass of the binder used.

  The electrode active material layer is basically formed on both sides of the current collector plate, but may be on one side if necessary. The thickness of the active material layer (per one side) is preferably 10 to 150 μm, more preferably 20 to 140 μm, and particularly preferably 30 to 120 μm. By setting the thickness within the above range, it is easy to achieve a high capacity because fewer current collectors and separators are required. On the other hand, it is easy to obtain high output characteristics because a large electrode area facing the counter electrode can be secured. .

  The negative electrode for a battery comprising a positive electrode using the organic compound of the present invention as an active material may be pre-doped with lithium ions prior to the production of the battery. The pre-doping method is not particularly limited, and examples thereof include a method in which metallic lithium is arranged near the negative electrode and then short-circuited to perform pre-doping, and a method in which metallic lithium is arranged near the negative electrode and then pre-doped at a constant current value. When lithium is doped in advance on a positive electrode using an organic compound as an active material, pre-doping of lithium ions into the negative electrode can be omitted.

<Battery comprising a positive electrode using an organic compound as an active material>
A battery comprising a positive electrode comprising the organic compound of the present invention as an active material comprises the battery negative electrode of the present invention. A battery comprising a positive electrode using the organic compound of the present invention as an active material exhibits high output characteristics.

  When forming a negative electrode for a battery comprising a positive electrode using an organic compound as an active material, including the non-graphitizable carbonaceous material of the present invention, a material containing an organic compound is used as the positive electrode material. Other materials constituting the battery such as a separator and an electrolytic solution are not particularly limited. Various materials conventionally used or proposed as a battery including a positive electrode using an organic compound as an active material can be used.

  For example, an organic radical compound or an organic polymer compound can be used as the positive electrode material. Examples of these organic compounds include, but are not limited to, compounds and polymers having a nitroxyl radical, compounds and polymers having an oxy radical, compounds and polymers having a nitrogen radical, and compounds and polymers having a fulvalene skeleton. It is not something. Two or more kinds of positive electrode materials containing these organic compounds can be used in combination. A positive electrode is formed by molding these positive electrode materials together with an appropriate binder and a carbon material for imparting conductivity to the electrodes.

The electrolytic solution is not particularly limited, but it is preferable to use a solution in which a lithium salt is dissolved in a solvent. Examples of the lithium salt include LiPF ₆ , LiClO ₄ , LiBF ₄ , LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiN (C ₂ F ₅ SO ₂ ) ₂ , Li (CF ₃ SO ₂ ) ₃ C, Li Known materials such as (C ₂ F ₅ SO ₂ ) ₃ C may be used, and these may be used alone or in combination.

  The solvent of the electrolytic solution is not particularly limited as long as it is non-proton donating and can be used for a normal lithium ion secondary battery. For example, organic solvents such as ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, γ-butyrolactone, tetrahydrofuran, dioxolane, sulfolane, dimethylformamide, dimethylacetamide, and N-methyl-2-pyrrolidone can be used. These solvents can be used alone or in admixture of two or more. The electrolytic solution may be gelled with a polymer or the like.

  A battery comprising a positive electrode made of an organic compound as an active material generally faces the positive electrode and negative electrode formed as described above with a liquid-permeable separator made of a nonwoven fabric or other porous material as necessary. And formed by immersing in an electrolytic solution. As a separator, the permeable separator which consists of a nonwoven fabric normally used for a secondary battery or another porous material can be used. Alternatively, a solid electrolyte made of a polymer gel impregnated with an electrolytic solution can be used instead of or together with the separator.

<Main resonance peak position of chemical shift value (negative electrode)>
For a negative electrode for a battery comprising a positive electrode using an organic compound containing a non-graphitizable carbonaceous material of the present invention as an active material, lithium is charged (dope) until it is fully charged, and ⁷ Li nucleus-solid NMR analysis is performed. The main resonance peak position of the chemical shift value relative to lithium chloride observed when performed is greater than 115 ppm, preferably greater than 118 ppm, more preferably greater than 120 ppm. Details of the ⁷ Li nucleus-solid NMR analysis are as described in the examples. Further, the main resonance peak position of the chemical shift value is usually 148 ppm or less, preferably 146 ppm or less, more preferably 144 ppm or less, and further preferably 142 ppm or less.

  As described above, the main resonance peak position of the chemical shift value based on lithium chloride is larger than 115 ppm, that is, the above main resonance peak position is observed from 115 ppm on the low magnetic field side, which is included in the negative electrode. In the non-graphitizable carbonaceous material, there are many occlusions of clustered lithium, that is, there is a large amount of clustered lithium that reversibly contributes to charge / discharge, and lithium ions lost due to irreversible side reactions during charge / discharge Means less. The small amount of lithium ions that are hardly generated and lost due to side reactions means that the increase in internal resistance of the battery due to side reaction products is suppressed, and the internal resistance of the battery is maintained at a low level. High output characteristics can be obtained in a battery comprising a positive electrode made of an active material. Further, by suppressing side reactions, local charge / discharge on the negative electrode and dendrite-like lithium deposition are suppressed, which contributes to improving the durability of the battery.

  When there is a large amount of clustered lithium, that is, when there is little loss of lithium in the negative electrode due to side reactions during charge and discharge, it is necessary to supplement the negative electrode with lithium by using an excessive amount of positive electrode containing metallic lithium and lithium ions during pre-doping This is advantageous in terms of cost.

  When a carbonaceous material having a main resonance peak position of a chemical shift value based on lithium chloride of 115 ppm or less is used, since the amount of clustered lithium is small, a large number of side reactions occur during charging and discharging. In a battery comprising a positive electrode using an organic compound as an active material as in the present invention, it is extremely difficult to obtain a battery having high output characteristics and high durability.

In order to adjust the main resonance peak position to a value within the above range, for example, a material containing a carbon precursor from which impurities have been removed by vapor phase deashing or liquid phase deashing is used as an inert gas at 1050 ° C. to 1400 ° C. The use of a non-graphitizable carbonaceous material produced by firing in an atmosphere for the negative electrode can be mentioned. Details of the ⁷ Li nucleus-solid NMR analysis are as described in the examples.

<Potassium element content and iron element content (negative electrode)>
The potassium element content of the negative electrode for a battery comprising a positive electrode comprising an organic compound containing a non-graphitizable carbonaceous material of the present invention as an active material is 0 from the viewpoint of suppressing side reactions between an impurity containing potassium and an electrolytic solution. 0.1 mass% or less is preferable, 0.05 mass% or less is more preferable, and 0.03 mass% or less is still more preferable. It is particularly preferred that the negative electrode contains substantially no potassium element. Moreover, the iron element content of the negative electrode for a battery comprising a positive electrode using the organic compound of the present invention as an active material is 0.02% by mass or less from the viewpoint of suppressing a side reaction between an impurity containing iron and an electrolytic solution. Preferably, it is 0.015 mass% or less, and more preferably 0.01 mass% or less. It is particularly preferable that the negative electrode contains substantially no iron element. Here, the phrase “substantially containing no potassium element or iron element” means that the potassium element content or the iron element content is determined by the fluorescent X-ray analysis described later (for example, analysis using “LAB CENTER XRF-1700” manufactured by Shimadzu Corporation). It means that it is below the detection limit value. When the potassium element content and the iron element content are not more than the above values, sufficiently high output characteristics and high durability are easily obtained in the battery of the present invention using the non-graphitizable carbonaceous material. Furthermore, battery safety problems due to short-circuiting when these metal elements are eluted and re-deposited in the electrolytic solution are easily avoided. Details of the measurement of the potassium element content and the iron element content are as described in the examples.

<Moisture absorption (negative electrode)>
The moisture absorption of a negative electrode for a battery comprising a positive electrode comprising an organic compound containing a non-graphitizable carbonaceous material of the present invention as an active material is preferably 50000 ppm or less, more preferably 30000 ppm or less, and particularly preferably 10000 ppm or less. The smaller the amount of moisture absorption, the smaller the amount of moisture adsorbed on the negative electrode, which is preferable because the generation of gas in the electrode due to moisture-induced side reactions is easily suppressed. The amount of moisture absorbed by the negative electrode can be reduced, for example, by reducing the amount of oxygen atoms contained in the non-graphitizable carbonaceous material. The moisture absorption amount of the negative electrode is measured using, for example, a Karl Fischer.

  EXAMPLES Hereinafter, the present invention will be specifically described by way of examples, but these do not limit the scope of the present invention. The analytical methods and the methods for measuring physical properties are described below.

< ⁷ Li nuclear-solid NMR analysis method>
The negative electrode containing the non-graphitizable carbonaceous material doped with lithium ions in a fully charged state was taken out of the cell, and all the negative electrode from which the electrolytic solution had been wiped was filled in an NMR sample tube. ⁷ Li nuclear-solid NMR analysis was performed using “Nuclear Magnetic Resonance Apparatus AVANCE300” manufactured by BRUKER. In the measurement, lithium chloride was used as a reference substance, and this was set to 0 ppm.

<Measuring method of average interplanar spacing _d002 of (002) plane>
Using “MiniFlex II” manufactured by Rigaku Corporation, an X-ray diffraction pattern was obtained using CuKα rays monochromatized by a Ni filter by filling a non-graphitizable carbonaceous material powder in a sample holder. The peak position of the diffraction pattern is obtained by the barycentric method (a method of obtaining the barycentric position of the diffraction line and obtaining the peak position by the corresponding 2θ value), and using the diffraction peak on the (111) plane of the high-purity silicon powder for standard materials. Corrected. The wavelength of the CuKα ray was 0.15418 nm, and d ₀₀₂ was calculated according to the Bragg formula shown below.

<Measurement of metal element content>
The potassium element content and the iron element content were measured by the following methods. A carbon sample containing a predetermined potassium element and iron element is prepared in advance, and using a fluorescent X-ray analyzer, the relationship between the intensity of potassium Kα ray and the potassium element content, and the intensity of iron Kα ray and iron element content A calibration curve for the relationship was created. Next, the intensity of potassium Kα ray and iron Kα ray in the fluorescent X-ray analysis is measured for the sample (non-graphitizable carbonaceous material or negative electrode sample), and the potassium element content and iron element content are obtained from the calibration curve prepared earlier. It was. The fluorescent X-ray analysis was performed by the following procedure using “LAB CENTER XRF-1700” manufactured by Shimadzu Corporation. Using the upper irradiation system holder, the sample measurement area was within the circumference of 20 mm in diameter. The sample to be measured was placed by placing 0.5 g of the sample to be measured in a polyethylene container having an inner diameter of 25 mm, pressing the back with a plankton net, and covering the measurement surface with a polypropylene film. The X-ray source was set to 40 kV and 60 mA. For potassium, LiF (200) was used for the spectroscopic crystal and a gas flow proportional coefficient tube was used for the detector, and 2θ was measured in the range of 90 to 140 ° at a scanning speed of 8 ° / min. For iron, LiF (200) was used for the spectroscopic crystal, and a scintillation counter was used for the detector, and 2θ was measured in the range of 56 to 60 ° at a scanning speed of 8 ° / min.

<Measurement of average particle size by laser scattering method>
The average particle diameter (particle size distribution) of plant-derived char, carbon precursor, and volatile organic substance was measured by the following method. The sample was put into an aqueous solution containing 0.3% by mass of a surfactant (“Toriton X100” manufactured by Wako Pure Chemical Industries, Ltd.), treated with an ultrasonic cleaner for 10 minutes or more, and dispersed in the aqueous solution. The particle size distribution was measured using this dispersion. The particle size distribution measurement was performed using a particle size / particle size distribution measuring instrument (“Microtrack MT3000” manufactured by Nikkiso Co., Ltd.). Dv ₅₀ is the particle diameter at which the cumulative volume is 50%, and this value was taken as the average particle diameter.

Example 1
<Preparation of carbon precursor>
The coconut shell was carbonized at 500 ° C. and then crushed to obtain an coconut shell char having a particle diameter of about 2 mm. Halogen heat treatment was performed at 870 ° C. for 30 minutes while supplying nitrogen gas containing 2% by volume of hydrogen chloride gas at a flow rate of 18 L / min to 100 g of this coconut shell char. Thereafter, only the supply of hydrogen chloride gas was stopped, and while supplying nitrogen gas at a flow rate of 18 L / min, vapor phase deoxidation treatment was further performed at 870 ° C. for 30 minutes to obtain a carbon precursor.
The obtained carbon precursor was pulverized to an average particle size of 6 μm using a mixer mill (manufactured by Vander Scientific Co., Ltd., MM400), and then classified using Nanojet Mizer (manufactured by Aisin Nanotechnology Co., Ltd.). A carbon precursor (1) having an average particle diameter of 5 μm was obtained.

<Preparation of non-graphitizable carbonaceous material>
As a result of putting 5 g of the carbon precursor (1) prepared as described above into a graphite sheath, the sample layer height was 2 mm. Next, the temperature was raised to 1290 ° C. at a temperature rising rate of 10 ° C./min under a nitrogen flow rate of 5 L / min in a batch-type baking furnace, held for 30 minutes, and naturally cooled. After confirming that the furnace temperature had dropped to 200 ° C. or lower, the non-graphitizable carbonaceous material was taken out from the furnace. The recovered non-graphitizable carbonaceous material was 4.8 g, and the recovery rate was 96%.

<Analysis of ⁷ Li nucleus-solid NMR>
94 parts by mass of the non-graphitizable carbonaceous material prepared as described above, 6 parts by mass of PVDF (polyvinylidene fluoride) and 90 parts by mass of NMP (N-methylpyrrolidone) were mixed to obtain a slurry. The obtained slurry was applied to a copper foil having a thickness of 14 μm, dried and pressed to obtain an electrode having a thickness of 70 to 80 μm. The density of the obtained electrode was 0.9 to 1.1 g / cm ³ .
A negative electrode was used as a working electrode, and metallic lithium was used as a counter electrode and a reference electrode. As the electrolytic solution, ethylene carbonate / dimethyl carbonate (volume mixing ratio 3: 7) containing 1.2 M / LiPF ₆ electrolyte was used. A glass fiber nonwoven fabric was used for the separator. A coin cell was produced in a glove box under an argon atmosphere.
About the obtained half cell of the negative electrode, the charge / discharge test was done using the charge / discharge test apparatus (Toyo System Co., Ltd. make, "TOSCAT"). Lithium doping was performed at a rate of 10 mA / g up to a predetermined capacity (600 mAh / g) at which no metallic lithium was deposited with respect to the active material mass, and was fully charged by completing the doping. Here, the “predetermined capacity at which metallic lithium does not precipitate” refers to the upper limit charging capacity (mAh / g) at which metallic lithium is not precipitated by Li-NMR.
The fully charged negative electrode was subjected to ⁷ Li nucleus-solid NMR analysis to confirm the main resonance peak position of the chemical shift value based on lithium chloride.

<Battery evaluation>
-Production of positive electrode Poly (4-methacryloyloxy-2,2,6,6-tetramethylpiperidine-1-oxyl) (hereinafter referred to as PTMA) was used as a positive electrode active material. In a 24 mL ointment container, 10 mL of N-methyl-2-pyrrolidone (NMP) as a solvent and 15 mg of PTMA were added and stirred for 30 minutes to dissolve. There, 20 mg of conductive carbon black (manufactured by TIMCAL, Super P, registered trademark) and 18 mg of polyvinylidene fluoride (manufactured by Kureha, PVDF # 2200) as a binder were measured, and a rotating and rotating mixer (manufactured by Sinky, ARE-310) was used. A slurry was obtained by stirring and kneading. The obtained slurry was applied onto an aluminum foil having a thickness of 20 μm and dried at 80 ° C. The dry electrode was stretched by applying pressure using a roll press, punched into a circle, and vacuum dried at 120 ° C. for 12 hours to obtain a positive electrode.

-Preparation of negative electrode 94 mass parts of non-graphitizable carbonaceous materials, 6 mass parts of PVDF (polyvinylidene fluoride), and 90 mass parts of NMP (N-methylpyrrolidone) were mixed, and the slurry was obtained. The obtained slurry was applied to a copper foil having a thickness of 14 μm, dried and pressed to obtain an electrode. The density of the obtained electrode was 0.9 to 1.1 g / cm ³ .

-Negative electrode pre-doping The negative electrode was used as a working electrode, and metallic lithium was used as a counter electrode and a reference electrode. As the electrolytic solution, ethylene carbonate / dimethyl carbonate (volume mixing ratio 3: 7) containing 1.2 M / LiPF 6 electrolyte was used. A glass fiber nonwoven fabric was used for the separator. A coin cell was produced in a glove box under an argon atmosphere.
About the obtained negative electrode half cell, the charging / discharging test was done using the charging / discharging test apparatus (the Toyo System Co., Ltd. make, "TOSCAT"). Lithium doping was performed at a rate of 10 mA / g up to a predetermined capacity (600 mAh / g) at which no metallic lithium was deposited with respect to the active material mass, and was fully charged by completing the doping. Here, the “predetermined capacity at which metallic lithium does not precipitate” refers to an upper limit charging capacity at which metallic lithium is not precipitated by Li-NMR.
After the lithium ion doping was completed, the coin cell was disassembled in a glove box under an argon atmosphere, and the negative electrode was taken out. The negative electrode was washed with an ethylene carbonate / dimethyl carbonate (volume mixing ratio 3: 7) solvent and then dried to obtain a negative electrode pre-doped with lithium ions.

-Production of battery The negative electrode pre-doped with lithium ions and the positive electrode mixture containing PTMA were opposed to each other through a separator made of a glass fiber nonwoven fabric. As the electrolytic solution, ethylene carbonate / dimethyl carbonate (volume mixing ratio 3: 7) containing 1.2 M / LiPF ₆ electrolyte was used. A glass fiber nonwoven fabric was used for the separator. A coin cell was produced in a glove box under an argon atmosphere.

-Charging / discharging test About the obtained coin cell, the charging / discharging test was done using the charging / discharging test apparatus (the Toyo System Co., Ltd. make, "TOSCAT"). First, charge / discharge was performed at a rate of 10 mA / g with respect to the mass of the negative electrode active material. Next, after charging the negative electrode active material mass at a rate of 10 mA / g, discharging was performed at a rate of 50 mA / g. The discharge capacity when discharging at a rate of 10 mA / g is (A), the discharge capacity when discharging at a rate of 50 mA / g is (B), and the discharge capacity (B) / discharge capacity (A). The value calculated as a percentage of the discharge capacity maintenance rate. When the increase in the internal resistance of the battery is suppressed, a good discharge capacity retention ratio (B) / (A) (output characteristics) can be obtained. On the other hand, when 100 cycles of charge and discharge are performed at a rate of 10 mA / g with respect to the mass of the negative electrode active material, the discharge capacity at the first cycle is (C) and the discharge capacity at the 100th cycle is (D). The discharge capacity retention ratio calculated as a percentage of capacity (D) / discharge capacity (C) was determined. When the internal resistance increase of the battery is suppressed and uniform charge / discharge proceeds, a good discharge capacity retention ratio (D) / (C) (durability) can be obtained.

Example 2
<Preparation of non-graphitizable carbonaceous material>
5 g of the carbon precursor (1) prepared in the same manner as in Example 1 was mixed with 0.5 g of polystyrene (manufactured by Sekisui Chemical Co., Ltd., average particle size 400 μm, residual carbon ratio 1.2%).
5.5 g of this mixture was heated to 1290 ° C. at a heating rate of 10 ° C./min under a nitrogen flow rate of 5 L / min in a batch-type baking furnace, then held for 30 minutes and naturally cooled. After confirming that the furnace temperature had dropped to 200 ° C. or lower, the non-graphitizable carbonaceous material was taken out from the furnace. The non-graphitizable carbonaceous material recovered after firing by the above method was 4.8 g, and the recovery rate was 87%.

<Analysis of ⁷ Li nucleus-solid NMR>
A fully charged negative electrode was obtained in the same manner as in Example 1. The negative electrode was subjected to ⁷ Li nucleus-solid NMR analysis, and the main resonance peak position of the chemical shift value based on lithium chloride was confirmed.

<Battery evaluation>
-Production of positive electrode The same positive electrode as in Example 1 was used.

-Production of negative electrode A negative electrode was produced in the same manner as in Example 1.

-Negative electrode pre-doping The pre-doping process to the negative electrode was implemented by the same method as Example 1.

-Production of battery A battery was produced in the same manner as in Example 1.

Charge / discharge test Charge / discharge is carried out in the same manner as in Example 1, and the discharge capacity is calculated as a percentage of discharge capacity (B) / discharge capacity (A) and discharge capacity (D) / discharge capacity (C). The rate was determined.

Example 3
<Preparation of carbon precursor>
About 5 mm square Philippines coconut shell chips 100 g from Mindanao Island were immersed in 150 g of a 7.4% by mass citric acid aqueous solution, heated to 85 ° C., and heated for 3 hours. Thereafter, the mixture was cooled to room temperature and drained by filtration. This operation was performed 6 times and decalcification was performed. The decalcified coconut shell was dried at 80 ° C. under a vacuum of 1 Torr for 24 hours. 20 g of the coconut shell chip thus decalcified was placed in a crucible, and was used under a flow rate of 3 L / min (0.012 m / sec) of nitrogen stream with an oxygen content of 15 ppm using a KTF1100 furnace (inner diameter 70 mmΦ) manufactured by Koyo Thermo. The temperature was raised to 750 ° C./° C./minute and held for 60 minutes, then cooled over 6 hours, and taken out at 50 ° C. or less to obtain a carbide (carbon precursor).
The obtained carbon precursor was pulverized to an average particle size of 6 μm using a mixer mill (manufactured by Vander Scientific Co., Ltd., MM400), and then classified using Nanojet Mizer (manufactured by Aisin Nanotechnology Co., Ltd.). A carbon precursor (2) having an average particle diameter of 5 μm was obtained.

<Preparation of non-graphitizable carbonaceous material>
5 g of the carbon precursor (2) prepared as described above was fired in the same manner as in Example 2. The recovered non-graphitizable carbonaceous material was 4.8 g, and the recovery rate was 87%.

<Analysis of ⁷ Li nucleus-solid NMR>
A fully charged negative electrode was obtained in the same manner as in Example 1. The negative electrode was subjected to ⁷ Li nucleus-solid NMR analysis, and the main resonance peak position of the chemical shift value based on lithium chloride was confirmed.

<Battery evaluation>
-Production of positive electrode The same positive electrode as in Example 1 was used.

-Production of negative electrode A negative electrode was produced in the same manner as in Example 1.

-Negative electrode pre-doping The pre-doping process to the negative electrode was implemented by the same method as Example 1.

-Production of battery A battery was produced in the same manner as in Example 1.

Charge / discharge test Charge / discharge is carried out in the same manner as in Example 1, and the discharge capacity is calculated as a percentage of discharge capacity (B) / discharge capacity (A) and discharge capacity (D) / discharge capacity (C). The rate was determined.

Example 4
<Preparation of carbon precursor>
The coconut shell was carbonized at 500 ° C. and then crushed to obtain an coconut shell char having a particle diameter of about 2 mm. Halogen heat treatment was performed at 1150 ° C. for 30 minutes while supplying nitrogen gas containing 2% by volume of hydrogen chloride gas at a flow rate of 18 L / min to 100 g of this coconut shell char. Thereafter, only the supply of hydrogen chloride gas was stopped, and while supplying nitrogen gas at a flow rate of 18 L / min, vapor phase deoxidation treatment was further performed at 1150 ° C. for 30 minutes to obtain a hardly graphitized carbonaceous material.
The obtained non-graphitizable carbonaceous material was pulverized to an average particle size of 6 μm using a mixer mill (manufactured by Vander Scientific, Inc., MM400), and then nanojet mizer (manufactured by Aisin Nanotechnology Co., Ltd.) was used. Thus, a non-graphitizable carbonaceous material having an average particle diameter of 5 μm was obtained.

<Analysis of ⁷ Li nucleus-solid NMR>
A fully charged negative electrode was obtained in the same manner as in Example 1. The negative electrode was subjected to ⁷ Li nucleus-solid NMR analysis, and the main resonance peak position of the chemical shift value based on lithium chloride was confirmed.

<Battery evaluation>
-Production of positive electrode The same positive electrode as in Example 1 was used.

-Production of negative electrode A negative electrode was produced in the same manner as in Example 1.

-Negative electrode pre-doping The pre-doping process to the negative electrode was implemented by the same method as Example 1.

-Production of battery A battery was produced in the same manner as in Example 1.

Charge / discharge test Charge / discharge is carried out in the same manner as in Example 1, and the discharge capacity is calculated as a percentage of discharge capacity (B) / discharge capacity (A) and discharge capacity (D) / discharge capacity (C). The rate was determined.

Comparative Example 1
<Preparation of non-graphitizable carbonaceous material>
5 g of carbon precursor (1) prepared in the same manner as in Example 1 was heated to 1020 ° C. at a heating rate of 10 ° C./min under a 5 L / min nitrogen flow rate in a batch-type firing furnace, and then held for 30 minutes. And cooled naturally. After confirming that the furnace temperature had dropped to 200 ° C. or lower, the non-graphitizable carbonaceous material was taken out from the furnace. The recovered non-graphitizable carbonaceous material was 4.9 g, and the recovery rate was 98%.

<Analysis of ⁷ Li nucleus-solid NMR>
A fully charged negative electrode was obtained in the same manner as in Example 1. The negative electrode was subjected to ⁷ Li nucleus-solid NMR analysis, and the main resonance peak position of the chemical shift value based on lithium chloride was confirmed.

<Battery evaluation>
-Production of positive electrode The same positive electrode as in Example 1 was used.

-Production of negative electrode A negative electrode was produced in the same manner as in Example 1.

-Pre-doping of negative electrode A pre-doping treatment for the negative electrode was performed in the same manner as in Example 1 except that the full charge capacity was 650 mAh / g.

-Production of battery A battery was produced in the same manner as in Example 1.

Charge / discharge test Charge / discharge is carried out in the same manner as in Example 1, and the discharge capacity is calculated as a percentage of discharge capacity (B) / discharge capacity (A) and discharge capacity (D) / discharge capacity (C). The rate was determined.

Comparative Example 2
<Preparation of non-graphitizable carbonaceous material>
A non-graphitizable carbonaceous material was obtained in the same manner as in Comparative Example 1 except that the treatment temperature was changed from 1020 ° C. to 1500 ° C. The recovered non-graphitizable carbonaceous material was 4.2 g, and the recovery rate was 84%.

<Analysis of ⁷ Li nucleus-solid NMR>
A fully charged negative electrode was obtained in the same manner as in Comparative Example 1. The negative electrode was subjected to ⁷ Li nucleus-solid NMR analysis, and the main resonance peak position of the chemical shift value based on lithium chloride was confirmed.

<Battery evaluation>
-Production of positive electrode The same positive electrode as in Example 1 was used.

-Production of negative electrode A negative electrode was produced in the same manner as in Example 1.

-Pre-doping of negative electrode A pre-doping treatment for the negative electrode was performed in the same manner as in Example 1 except that the full charge capacity was 400 mAh / g. In addition, when charging exceeding 400 mAh / g, since lithium precipitated, the full charge capacity was 400 mAh / g here.

-Production of battery A battery was produced in the same manner as in Example 1.

Charge / discharge test Charge / discharge is carried out in the same manner as in Example 1, and the discharge capacity is calculated as a percentage of discharge capacity (B) / discharge capacity (A) and discharge capacity (D) / discharge capacity (C). The rate was determined.

Comparative Example 3
<Preparation of non-graphitizable carbonaceous material>
The same method as Comparative Example 2 except that 5 g of carbon precursor (1) and 0.5 g of polystyrene (manufactured by Sekisui Plastics Co., Ltd., average particle size 400 μm, residual carbon ratio 1.2%) were mixed. A non-graphitizable carbonaceous material was obtained. The hardly graphitized carbonaceous material recovered after firing by the above method was 4.2 g, and the recovery rate was 76%.

<Analysis of ⁷ Li nucleus-solid NMR>
A fully charged negative electrode was obtained in the same manner as in Comparative Example 1. The negative electrode was subjected to ⁷ Li nucleus-solid NMR analysis, and the main resonance peak position of the chemical shift value based on lithium chloride was confirmed.

<Battery evaluation>
-Production of positive electrode The same positive electrode as in Example 1 was used.

-Production of negative electrode A negative electrode was produced in the same manner as in Example 1.

-Pre-doping of negative electrode A pre-doping treatment for the negative electrode was performed in the same manner as in Example 1 except that the full charge capacity was 400 mAh / g. In addition, when charging exceeding 400 mAh / g, since lithium precipitated, the full charge capacity was 400 mAh / g here.

-Production of battery A battery was produced in the same manner as in Example 1.

Charge / discharge test Charge / discharge is carried out in the same manner as in Example 1, and the discharge capacity is calculated as a percentage of discharge capacity (B) / discharge capacity (A) and discharge capacity (D) / discharge capacity (C). The rate was determined.

Comparative Example 4
<Preparation of carbon precursor>
About 20 mm square Philippine Mindanao coconut shell chips 20 g are put in a crucible, and using a KTF1100 furnace (inner diameter 70 mmΦ) manufactured by Koyo Thermo under a flow of nitrogen of 3 L / min (0.012 m / sec) with an oxygen content of 15 ppm. The temperature was raised to 750 ° C. at 10 ° C./min and held for 60 minutes, then cooled over 6 hours, and taken out at 50 ° C. or less to obtain a carbide. The obtained carbide was immersed in 100 g of a 7.4% by mass citric acid aqueous solution, heated to 80 ° C., and heated for 4 hours. Thereafter, the mixture was cooled to room temperature and drained by filtration. This operation was performed 5 times and decalcification was performed. The decalcified coconut shell was dried at 80 ° C. under a vacuum of 1 Torr for 24 hours.
The obtained carbon precursor was pulverized to an average particle size of 6 μm using a mixer mill (manufactured by Vander Scientific Co., Ltd., MM400), and then classified using Nanojet Mizer (manufactured by Aisin Nanotechnology Co., Ltd.). A carbon precursor (4) having an average particle diameter of 5 μm was obtained.

<Preparation of non-graphitizable carbonaceous material>
5 g of the carbon precursor (4) prepared as described above was fired in the same manner as in Comparative Example 3. The recovered non-graphitizable carbonaceous material was 4.3 g, and the recovery rate was 78%.

<Analysis of ⁷ Li nucleus-solid NMR>
A fully charged negative electrode was obtained in the same manner as in Example 1. The negative electrode was subjected to ⁷ Li nucleus-solid NMR analysis, and the main resonance peak position of the chemical shift value based on lithium chloride was confirmed.

<Battery evaluation>
-Production of positive electrode The same positive electrode as in Example 1 was used.

-Production of negative electrode A negative electrode was produced in the same manner as in Example 1.

-Pre-doping of negative electrode A pre-doping treatment for the negative electrode was performed in the same manner as in Example 1 except that the full charge capacity was 400 mAh / g. In addition, when charging exceeding 400 mAh / g, since lithium precipitated, the full charge capacity was 400 mAh / g here.

-Production of battery A battery was produced in the same manner as in Example 1.

Charge / discharge test Charge / discharge is carried out in the same manner as in Example 1, and the discharge capacity is calculated as a percentage of discharge capacity (B) / discharge capacity (A) and discharge capacity (D) / discharge capacity (C). The rate was determined.

Comparative Example 5
<Analysis of ⁷ Li nucleus-solid NMR>
A fully charged graphite material was obtained in the same manner as in Comparative Example 1 except that artificial graphite particles having an average particle size of 10 μm were used instead of the non-graphitizable carbonaceous material. The graphite material was subjected to ⁷ Li nucleus-solid NMR analysis to confirm the main resonance peak position of the chemical shift value based on lithium chloride.

<Battery evaluation>
-Production of positive electrode The same positive electrode as in Example 1 was used.

-Production of negative electrode A negative electrode was produced in the same manner as in Example 1.

-Pre-doping of negative electrode A pre-doping treatment for the negative electrode was performed in the same manner as in Example 1 except that the full charge capacity was 400 mAh / g.

-Production of battery A battery was produced in the same manner as in Example 1.

Charge / discharge test Charge / discharge is carried out in the same manner as in Example 1, and the discharge capacity is calculated as a percentage of discharge capacity (B) / discharge capacity (A) and discharge capacity (D) / discharge capacity (C). The rate was determined.

The production conditions of the carbonaceous material in each example and each comparative example, the evaluation results of the physical properties of the obtained carbonaceous material, and the evaluation results of the battery characteristics are shown in the following tables, respectively.
A battery produced using the negative electrode of the present invention exhibited high durability as well as high output characteristics. On the other hand, in the battery produced using the carbonaceous material of each comparative example, it could not be said that output characteristics and durability were sufficient.

  According to the battery negative electrode including the positive electrode using the organic compound of the present invention as an active material and the battery using the negative electrode, an increase in the internal resistance of the battery can be suppressed, and high output characteristics and high durability can be obtained. Therefore, it can be suitably used for in-vehicle applications such as a hybrid vehicle (HEV) and an electric vehicle (EV).

Claims (5)

A negative electrode containing a non-graphitizable carbonaceous material having a chemical shift value with lithium chloride as a reference substance observed by ⁷ Li nucleus-solid NMR analysis of the non-graphitizable carbonaceous material when fully charged A negative electrode for a battery comprising a positive electrode having an organic compound as an active material, the main resonance peak position of which is greater than 115 ppm. 2. The average interplanar spacing d ₀₀₂ of the (002) plane calculated by using the Bragg equation by wide-angle X-ray diffraction of the non-graphitizable carbonaceous material is in the range of 0.36 to 0.42 nm. Negative electrode.   The negative electrode according to claim 1, wherein the non-graphitizable carbonaceous material is derived from a plant-derived carbon precursor.   The negative electrode according to any one of claims 1 to 3, wherein the potassium element content is 0.1 mass% or less and the iron element content is 0.02 mass% or less.   A battery comprising a negative electrode according to any one of claims 1 to 4, comprising a positive electrode using an organic compound as an active material.

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