JP6864250B2 - Carbon material and non-aqueous secondary battery - Google Patents

Description

The present invention relates to a carbon material and a non-aqueous secondary battery provided with a negative electrode for a non-aqueous secondary battery using the carbon material.

In recent years, with the miniaturization of electronic devices, the demand for high-capacity secondary batteries has been increasing. In particular, lithium-ion secondary batteries having a higher energy density and excellent high-current charge / discharge characteristics than nickel-cadmium batteries and nickel-hydrogen batteries have been attracting attention. Conventionally, increasing the capacity of lithium-ion secondary batteries has been widely studied, but in recent years, there has been an increasing demand for higher performance of lithium-ion secondary batteries, and further increasing the capacity and input / output. , It is required to achieve a long life.

It is known that a carbon material such as graphite is used as an active material for a negative electrode in a lithium ion secondary battery. Above all, when graphite having a high degree of graphitization is used as an active material for a negative electrode for a lithium ion secondary battery, a capacity close to the theoretical capacity of graphite occlusion of 372 mAh / g can be obtained, and further, cost and durability can be obtained. It is known that it is preferable as an active material for a negative electrode because of its excellent properties. On the other hand, when the density of the active material layer containing the negative electrode material is increased in order to increase the capacity, the material is destroyed and deformed, resulting in an increase in the charge / discharge irreversible capacity during the initial cycle, a decrease in the large current charge / discharge characteristics, and a decrease in the cycle characteristics. There was a problem such as a decrease.

In order to solve the above problem, for example, in Patent Document 1, spherical natural graphite is produced by subjecting scaly natural graphite to mechanical energy treatment, and further, spherical natural graphite is used as nuclear graphite on the surface thereof. A technique for improving filling property and high-speed charge / discharge characteristics by coating with amorphous carbon is disclosed.

Patent Document 2 describes a carbonaceous composite carbon material formed by adhering carbides of an organic substance on the surface of a graphite carbonaceous material, wherein the amount of carbides of the organic substance is 12 weights as the amount of residual carbon with respect to 100 parts by weight of the graphite carbonaceous material. Non-aqueous solvent secondary battery with high discharge capacity, low charge / discharge irreversible capacity during initial cycle, and high safety against electrolyte solution by adjusting to 0.1 part by weight or more. Is disclosed that According to Patent Document 3, when TG-DTA measurement is performed, the DTA (Differential Thermal Analysis) curve obtained is the first peak on the relatively low temperature side derived from the non-graphite carbon film and the particulate graphite. Negative electrode activity for non-aqueous electrolyte secondary batteries, which has a second peak on the relatively high temperature side from which it is derived, and has a peak temperature difference of 60 to 160 ° C. between the first peak and the second peak. It is disclosed that a non-aqueous solvent secondary battery with reduced initial resistance can be obtained by using a substance.
Patent Document 4 describes a negative electrode active material capable of storing and releasing lithium, wherein the negative electrode active material is a composite carbon particle having a coating layer of low crystalline carbon on the surface of a graphite core material, and the coating layer has a coating layer. It has C = O, C-OH and CO functional groups, and the content of oxygen atoms in the total amount of carbon atoms and oxygen atoms of the coating layer is 2 atom% to 5 atom%, and the heat in the air. In the weighing method, it has at least one oxidation peak in each temperature range of 350 ° C. or higher and lower than 600 ° C. and 600 ° C. or higher and 850 ° C. or lower, and has a peak at the highest temperature in the range of 350 ° C. or higher and 850 ° C. or lower. By using a negative electrode active material in which the peak temperature difference between the oxidation peak and the oxidation peak having the peak at the lowest temperature is 300 ° C. or less, a non-aqueous solvent secondary battery having improved cycle life and high temperature storage characteristics can be obtained. Is disclosed.

Japanese Unexamined Patent Publication No. 2000-340232 Japanese Unexamined Patent Publication No. 09-213328 Japanese Unexamined Patent Publication No. 2013-191302 International Publication No. 2012/039477

However, according to the study by the present inventors, the composite graphite in which the graphite surface disclosed in Patent Documents 1 to 4 is coated with amorphous carbon has a structure in which the scaly graphite particles used as a raw material lack denseness. However, since the surface of the particles is covered with amorphous carbon, the specific surface area is reduced, the Li ion insertion / desorption sites of the particles are small, and there is room for improvement in improving the input / output characteristics of the battery.
In general, it is known that by using graphite particles having a large specific surface area, the Li ion insertion / desorption sites of the graphite particles can be widely used, so that the input / output characteristics when used as a battery are improved.
On the other hand, the carbonaceous material of graphite particles coated with the carbonaceous material has lower crystallinity than graphite and has a structure in which Li ions can be easily inserted and removed, so that the input / output characteristics of a battery can be improved. I know it. That is, it is considered that the input / output characteristics can be further improved by increasing the specific surface area and lowering the crystallinity of the graphite particles. However, when graphite particles are coated with a carbonaceous material in order to increase the region of low crystallinity where Li ions are easily inserted and removed, the fine structure of the particle surface is covered, so that the specific surface area is increased and the carbonaceous material is increased. There is a trade-off between the increase in the low crystalline region due to the coating of.
Further, if the proportion of carbonaceous material having low crystallinity is increased, the composite particle becomes hard because the carbonaceous material is harder than graphite, and when trying to increase the density of the negative electrode material by pressing, the higher the proportion of carbonaceous material, the higher the ratio. A press load was required.

The present invention has been made in view of such a background technique, and the problem is that the particles are compressed with excellent input / output characteristics and a lower load, which breaks away from the conventional trade-off relationship between the specific surface area and the low crystalline region. It is an object of the present invention to provide a carbon material for a non-aqueous secondary battery having press characteristics that can be achieved, and as a result, to provide a high-performance non-aqueous secondary battery.

As a result of diligent studies to solve the above problems, the present inventors have obtained a carbon material for a non-aqueous secondary battery capable of occluding and releasing lithium ions, and the carbon material is a granulated carbon material. The surface of the battery contains a carbonaceous substance, and DTA (Differential Thermal) measured by TG-DTA.
Analysis) It has been found that a carbon material for a non-aqueous secondary battery having excellent input / output characteristics and press characteristics can be obtained by satisfying a specific value for the peak of the curve, and the present invention has been completed.
The reason why the carbon material according to the present invention exerts the above effect is presumed to be as follows.
The carbon material according to the present invention has a first peak on the relatively low temperature side that exists in the range of 500 ° C. or higher and 1000 ° C. or lower at the time of TG-DTA measurement, as compared with the conventional carbon material containing a carbonaceous substance on the particle surface. Is high. This first peak is considered to be mainly derived from the combustion of low crystalline carbonaceous components. That is, since the low crystallinity carbonaceous substance component is present on the surface of the graphite particles as nuclei without being unevenly distributed, the insertion and desorption of Li ions are good.
That is, it is considered that the specific surface area has the effect of improving the input / output characteristics and the low crystalline carbonaceous material has the effect of improving the input / output characteristics.
Further, the carbon material according to the present invention does not have the low crystalline carbon material component unevenly distributed on the surface of the granulated carbon material as the core, as compared with the carbon material containing the conventional carbon material on the particle surface. Since it exists, it has a pressing property that allows particles to be compressed with a lower load because hard portions are not unevenly distributed when the negative electrode material is densified by a press machine or the like.

That is, the first gist of the present invention is a carbon material for a non-aqueous secondary battery containing a carbonaceous substance on the surface of the granulated carbon material, and DTA (Differential) obtained when TG-DTA measurement is performed.
The Thermal Analysis) curve has a first peak on the relatively low temperature side and a second peak on the relatively high temperature side in the range of 500 ° C. or higher and 1000 ° C. or lower, and the first peak and the first peak. It exists in a carbon material for a non-aqueous secondary battery, characterized in that the peak of 2 satisfies the following formula 1.
(Equation 1)
(DTA [μV] at the first peak) / (DTA [μV] at the second peak) ≧ 0.4

Another gist of the present invention is to provide a positive electrode and a negative electrode capable of occluding and releasing lithium ions, and an electrolyte, and the negative electrode includes a current collector and a negative electrode active material layer formed on the current collector. It is present in a non-aqueous secondary battery characterized in that the negative electrode active material layer contains the above-mentioned carbon material.

The carbon material of the present invention provides a non-aqueous secondary battery having excellent input / output characteristics and press characteristics capable of compressing particles with a lower load by using it as a negative electrode active material for a non-aqueous secondary battery. be able to.

It is a graph which shows the TG-DTA measurement result of the carbon material of this invention.

Hereinafter, the contents of the present invention will be described in detail. The description of the constituent requirements of the invention described below is an example (representative example) of the embodiment of the present invention, and the present invention is not specified in these forms unless the gist thereof is exceeded.

<Types of carbon materials for non-aqueous secondary batteries>
The carbon material for a non-aqueous secondary battery capable of storing and releasing lithium ions of the present invention contains a carbonaceous substance on the surface of the granulated carbon material, and has a peak of a DTA (Differential Thermal Analysis) curve measured by TG-DTA. Is not particularly limited as long as it satisfies a specific value, but for example, a carbonaceous material is contained on the surface of a carbonaceous material such as graphite or a carbonaceous material having a small degree of graphitization, and among them, it is easily commercially available. Furthermore, it is preferable that the material has excellent input / output characteristics and press characteristics capable of compressing particles with a lower load as compared with the case where other active materials for negative electrodes are used. Further, examples of graphite include natural graphite and artificial graphite, and natural graphite is more preferable from the viewpoint of good press characteristics capable of compressing particles with a high capacity and a low load.
Further, as the graphite, those having few impurities are preferable, and graphite having few impurities can be obtained by subjecting various known purification treatments.

Natural graphite, by its nature, scaly black lead (Flake Graphite), scaly graphite (Crystal L
ine Graphite), massive graphite (Vein Graphite), soil graphite (Amorphous Graphite) ("Granular Material Process Technology Collection" (Industrial Technology Center Co., Ltd., published in 1974)) Graphite section, and " HANDBOOKOF CARBON, GRAPHITE, DIAMOND AND FULLERENES "(Noyes PubLicatio)
See (issued by ns)). The degree of graphitization is highest in scaly graphite and massive graphite at 100%, followed by scaly graphite at 99.9%, which is suitable in the present invention.

The production areas of scaly natural graphite are mainly Madagascar, China, Brazil, Ukraine, Canada, etc., and the production areas of scaly graphite are mainly Sri Lanka. The main source of soil graphite is the Korean Peninsula,
China, Mexico, etc.
Among the natural graphites, for example, scaly, scaly, or lumpy natural graphite, highly purified scaly graphite, spheroidized natural graphite described later (hereinafter, may be referred to as spheroidized natural graphite) and the like can be mentioned. Be done. Above all, it is preferable from the viewpoint that suitable dense pores can be formed inside the carbon material and excellent particle filling property and charge / discharge load characteristics are exhibited.

Examples of artificial graphite include coal tar pitch, coal-based heavy oil, atmospheric residual oil, petroleum-based heavy oil, aromatic hydrocarbons, nitrogen-containing cyclic compounds, sulfur-containing cyclic compounds, polyphenylene, polyvinyl chloride, and polyvinyl. Organic substances such as alcohol, polyacrylonitrile, polyvinyl butyral, natural polymers, polyphenylene sulfide, polyphenylene oxide, furfuryl alcohol resin, phenol-formaldehyde resin, and imide resin are calcined and graphitized, or bulk mesophase is graphitized. Can be mentioned.
Further, a granulated artificial graphite obtained by adding a graphitizing catalyst to a graphitizable aggregate or graphite such as bulk mesophase and a graphitizable organic substance, mixing them, firing them, and then pulverizing them is used. You can also do it.
The calcination temperature can be in the range of 2500 ° C. or higher and 3200 ° C. or lower, and a silicon-containing compound, a boron-containing compound, or the like can be used as a graphitization catalyst at the time of calcination.

Examples of the carbonaceous material having a small degree of graphitization include those obtained by calcining an organic material at a temperature of less than 2500 ° C., and specific examples thereof include bulk mesophase and amorphous carbon. Organic substances include coal-based heavy oils such as coal tar pitch and dry distillate liquefied oil; direct-retaining heavy oils such as atmospheric residual oil and vacuum residual oil; ethylene tar produced as a by-product during thermal decomposition of crude oil and naphtha. Petroleum-based heavy oils such as decomposition heavy oils; aromatic hydrocarbons such as acenaphthalene, decacyclene and anthracene; nitrogen-containing cyclic compounds such as phenazine and acrydin; sulfur-containing cyclic compounds such as thiophene; aliphatic cyclic compounds such as adamantan Compounds: Polyphenylene such as biphenyl and terphenyl, polyvinyl esters such as polyvinyl chloride, polyvinyl acetate and polyvinyl butyral, and thermoplastic polymers such as polyvinyl alcohol can be mentioned.

Examples of the bulk mesophase include a carbonaceous material obtained by heat-treating a petroleum-based heavy oil, a coal-based heavy oil, and a straight-running heavy oil at 400 to 600 ° C.

Examples of the amorphous carbon include particles obtained by calcining the bulk mesophase and particles obtained by calcining the carbonaceous material precursor and calcining the particles.

The firing temperature of amorphous carbon can be 600 ° C. or higher, preferably 900 ° C. or higher, more preferably 950 ° C. or higher, and usually less than 2500 ° C., depending on the degree of crystallinity. It is preferably in the range of 2000 ° C. or lower, more preferably 1400 ° C. or lower.
At the time of firing, acids such as phosphoric acid, boric acid and hydrochloric acid, and alkalis such as sodium hydroxide can be mixed with the organic substance.

Further, the carbon material for a non-aqueous secondary battery of the present invention may contain oxides and other metals. Examples of other metals include metals that can be alloyed with Li such as Sn, Si, Al, and Bi.

<Manufacturing method of carbon material for non-aqueous secondary batteries>
The carbon material for a non-aqueous secondary battery of the present invention contains a carbonaceous substance on the surface of the granulated carbon material, and the peak of the DTA (Differential Thermal Analysis) curve measured by TG-DTA satisfies a specific value. Although there is no particular limitation, as one of the means to achieve it, at least one of the mechanical energies of impact, compression, friction, and shearing force is applied to granulate the raw material carbon material, and the granulation step is described below. It can be produced by coating the surface of a granulated carbon material obtained by performing in the presence of a granulator satisfying the conditions 1) and 2) with a carbonaceous material.

(Conditions for granulation process)
1) Liquid during the step of granulating the raw material carbon material 2) When the granulator contains an organic solvent, at least one of the organic solvents does not have a flash point or has a flash point. The flash point is 5 ° C or higher.

If the granulation step is provided, another step may be further provided if necessary. Another step may be carried out independently, or a plurality of steps may be carried out at the same time.

When the granulation treatment is performed by the above method, a liquid cross-linking adhesive force between graphite particles is generated by a granulator having specified physical properties, and carbon material particles can be more firmly adhered to each other, so that the specific surface area is increased. Fine particles with a large number of Li ion insertion / desorption sites adhere to the base material that becomes the granulated carbon material (hereinafter referred to as the granulated carbon material), and / or take a structure enclosed in the granulated carbon material. Since it becomes easy, it becomes possible to produce a granulated carbon material having a high specific surface area and many Li insertion / desorption sites.
By using the granulated carbon material having the above characteristics as a core, it becomes possible for the low crystalline carbonaceous material component to exist without being unevenly distributed on the surface of the granulated carbon material as the core.
As a more preferable embodiment of the above-mentioned production method, a production method including the following first to fourth steps can be mentioned.

(1st step) Step of adjusting the particle size of the raw material carbon material (2nd step) Step of mixing the raw material carbon material and the granulator (3rd step) Step of granulating the raw material carbon material (4th step) the grain carbon material, step affixing a low crystallinity carbonaceous material than granulating the carbonaceous material to further below, describe these steps.

(First step) Step of adjusting the particle size of the raw material carbon material The raw material carbon material used in the present invention is not particularly limited, and the above-mentioned carbon material such as graphite or a carbonaceous material having a small degree of graphitization can be used. Above all, it is preferable to use natural graphite because of its high crystallinity and high capacity.

The average particle size (d50) of these raw material carbon materials is preferably 1 μm or more, more preferably 2 μm or more, still more preferably 3 μm or more, preferably 80 μm or less, more preferably 50 μm or less, still more preferably 35 μm or less, and very preferably. Is 20 μm or less, particularly preferably 10 μm or less, and most preferably 8 μm or less. The average particle size can be measured by the method described later.

When the average particle size is within the above range, the fine powder generated during the granulation process can be granulated while adhering to the base material to be the granulated carbon material or wrapping it inside the base material to form a sphere. It is possible to obtain a granulated carbon material having a high degree and a small amount of fine powder.

Examples of the method for adjusting the average particle size (d50) of the raw material carbon material within the above range include a method of pulverizing and / or classifying the carbon material particles.
The apparatus used for crushing is not particularly limited, and examples of the coarse crusher include a shear mill, a jaw crusher, an impact crusher, a cone crusher, and the like, and examples of the intermediate crusher include a roll crusher and a hammer mill. Examples of the fine crusher include a mechanical crusher, an air flow crusher, a swirling flow crusher, and the like. Specific examples thereof include ball mills, vibration mills, pin mills, stirring mills, jet mills, cyclone mills, and turbo mills. In particular, when obtaining carbon material particles of 10 μm or less, it is preferable to use an air flow type crusher or a swirling flow type crusher.
The apparatus used for the classification process is not particularly limited, but for example, in the case of dry sieving, a rotary sieve, a swaying sieve, a rotating sieve, a oscillating sieve and the like can be used, and the dry air flow type sieving can be used. In this case, a gravity type classifier, an inertial force type classifier, a centrifugal force type classifier (classifier, cyclone, etc.) can be used, and a wet sieving machine, a mechanical wet classifier, a hydraulic classifier, and a settling classifier can be used. , A centrifugal wet classifier or the like can be used.

Further, it is preferable that the raw material carbon material satisfies the following physical properties.
The ash content contained in the raw material carbon material is preferably 1% by mass or less, more preferably 0.5% by mass or less, and further preferably 0.1% by mass or less, based on the total mass. Further, the lower limit of the ash content is preferably 1 ppm or more.
When the ash content is within the above range, when a non-aqueous secondary battery is used, the deterioration of battery performance due to the reaction between the negative electrode material and the electrolytic solution during charging and discharging can be suppressed to a negligible extent. In addition, since the production of the negative electrode material does not require a large amount of time, energy, and equipment for preventing pollution, an increase in cost can be suppressed.

The aspect ratio of the raw material carbon material is preferably 3 or more, more preferably 5 or more, still more preferably 10 or more, and particularly preferably 15 or more. Further, it is preferably 1000 or less, more preferably 500 or less, still more preferably 100 or less, and particularly preferably 50 or less. The aspect ratio is measured by the method of Examples described later. When the aspect ratio is within the above range, it is difficult to form large particles having a particle size of about 100 μm, and on the other hand, it becomes easy to obtain a strong granulated carbon material.

The plane spacing (d002) and crystallite size (Lc) of the 002 planes of the raw material carbon material by the X-ray wide-angle diffraction method are usually 3.37 Å or less for (d002) and 900 Å or more for (Lc), and (d0).
It is preferable that 02) is 3.36 Å or less and (Lc) is 950 Å or more. Surface spacing (d0
02) and the crystallinity size (Lc) are values indicating the crystallinity of the negative electrode material bulk, and the smaller the value of the interplanar spacing (d002) of the 002 surface, the larger the crystallinity size (Lc). The more crystalline the negative electrode material is, the closer the amount of lithium entering the graphite layers is to the theoretical value, and the larger the capacity is. If the crystallinity is low, excellent battery characteristics (high capacity and low irreversible capacity) when a highly crystalline carbon material is used for the electrode are not exhibited. It is particularly preferable that the above ranges are combined for the interplanar spacing (d002) and the crystallite size (Lc).
X-ray diffraction is measured by the following method. The material is a mixture of carbon powder and X-ray standard high-purity silicon powder of about 15% by mass, and the CuKα ray monochromated with a graphite monochromator is used as the radiation source. Measure the line diffraction curve. Then, the interplanar spacing (d002) and the crystallite size (Lc) are determined using the Gakushin method.

The packed structure of the raw material carbon material depends on the size and shape of the particles, the degree of interaction between the particles, etc., but in this specification, tapping density is applied as one of the indexes for quantitatively discussing the packed structure. It is also possible to do. In the study by the present inventors, it has been confirmed that in lead particles having substantially the same true density and average particle size, the tap density is higher as the shape is spherical and the particle surface is smoother. That is, in order to increase the tap density, it is important to make the shape of the particles rounded to make them spherical, and to maintain smoothness by removing hangnail and defects on the particle surface. When the particle shape approaches a spherical shape and the particle surface is smooth, the filling property of the powder is greatly improved. The tapping density of the raw material carbon material is preferably 0.1 g / cm ³ or more, more preferably 0.2 g / cm ³ or more, and further preferably 0.3 g / cm ³ or more. The tapping density is measured by the method described later in the examples.

The argon ion laser Raman spectrum of the raw material carbon material is used as an index showing the properties of the surface of the particles. 1 in the argon ion laser Raman spectrum of the raw material graphite
Raman R value is the peak intensity ratio in the vicinity of 1360 cm ^-1 to the peak intensity at around 580 cm ^-1 is preferably 0.05 to 0.9, more preferably 0.05 to 0.7, More preferably, it is 0.05 or more and 0.5 or less. The R value is an index showing the crystallinity near the surface of the carbon particles (from the particle surface to about 100 Å), and the smaller the R value, the higher the crystallinity or the undisturbed crystal state. The Raman spectrum is measured by the method shown below. Specifically, the particles to be measured are naturally dropped into the measurement cell of the Raman spectrometer to fill the sample, and while irradiating the measurement cell with an argon ion laser light, the measurement cell is placed in a plane perpendicular to the laser light. Measure while rotating. The wavelength of the argon ion laser light is 514.5 nm.

The X-ray wide-angle diffraction method of the raw material carbon material is used as an index showing the crystallinity of the entire particle, and is based on the strength 3R (101) of 101 planes based on the rhombic crystal structure by the X-ray wide-angle diffraction method and the hexagonal crystal structure. The ratio of 3R / 2H to the strength 2H (101) of the 101 surface is preferably 0.1 or more, more preferably 0.15 or more, and further preferably 0.2 or more. The rhombohedral crystal structure is a crystal form in which the accumulation of graphite network structures is repeated every three layers. The hexagonal crystal structure is a crystal form in which the accumulation of graphite network structures is repeated every two layers. In the case of scaly graphite showing a crystal morphology having a large proportion of the rhombohedral crystal structure 3R, the acceptability of Li ions is higher than that of graphite having a small proportion of the rhombohedral crystal structure 3R.

The specific surface area of the raw material carbon material by the BET method is preferably 1 m ² / g or more and 30 m ² / g or less, more preferably 2 m ² / g or more and 20 m ² / g or less, and further preferably 5 m ² / g or more and 15 m ² / g. It is as follows. The specific surface area by the BET method is measured by the method of Examples described later. When the specific surface area of the raw material carbon material is within the above range, the acceptability of Li ions becomes good, and it is possible to prevent a decrease in battery capacity due to an increase in irreversible capacity.

(Second step) Step of mixing the raw material carbon material and the granulating agent In order to obtain the carbon material for the non-aqueous secondary battery of the present invention, it is preferable to granulate the raw material carbon material using the granulating agent. The granulating agent is 1) a liquid during the step of granulating the raw material carbon material and 2) when the granulating agent contains an organic solvent, at least one of the organic solvents does not have a flash point or has a flash point. When the above is satisfied, the condition that the flash point is 5 ° C. or higher is satisfied.
By having a granulating agent that satisfies the above requirements, the granulating agent liquid-bridges between the raw material carbon materials during the subsequent step of granulating the raw material carbon material in the third step, so that the liquid between the raw material carbon materials is liquid. Since the attractive force generated by the negative pressure of the capillary tube in the bridge and the surface tension of the liquid acts as the liquid cross-linking adhesive force between the particles, the liquid cross-linking adhesive force between the raw material carbon materials increases, and the raw material carbon material may adhere more firmly. It will be possible.

In the present invention, the strength of the liquid cross-linking adhesive force between the raw material carbon materials due to the liquid cross-linking between the raw material carbon materials is proportional to the γcosθ value (here, γ: surface tension of the liquid, θ: Contact angle between liquid and particles). That is, when granulating the raw material carbon material, the granulating agent preferably has high wettability with the raw material carbon material, and specifically, a granulating agent having cosθ> 0 so that γcosθ value> 0. It is preferable to select it, and it is preferable that the contact angle θ of the granulating agent with the carbon material measured by the following measuring method is less than 90 °.

<Measurement method of contact angle θ with carbon material>
1.2 μl of granulating agent is dropped on the surface of HOPG, and the contact angle is measured when the wet spread converges and the rate of change of the contact angle θ per second becomes 3% or less (also called steady state). Measure with an apparatus (automatic contact angle meter DM-501 manufactured by Kyowa Interface Science Co., Ltd.). Here, when a granulator having a viscosity at 25 ° C. of 500 cP or less is used, the value at 25 ° C. is used, and when a granulator having a viscosity at 25 ° C. higher than 500 cP is used, the temperature is up to a temperature at which the viscosity is 500 cP or less. It is the measured value of the contact angle θ at the heated temperature.

Further, as the contact angle θ between the raw material carbon material and the granulating agent is closer to 0 °, the γcos θ value becomes larger, so that the liquid cross-linking adhesive force between the carbon material particles increases, and the carbon material particles adhere to each other more firmly. It becomes possible. Therefore, the contact angle θ of the granulator with the carbon material is more preferably 85 ° or less, further preferably 80 ° or less, further preferably 50 ° or less, and 30 ° or less. It is particularly preferable that the temperature is 20 ° or less, and most preferably 20 ° or less.

By using a granulating agent having a large surface tension γ, the γcosθ value becomes large and the adhesive force of the carbon material particles is improved. Therefore, the γ is preferably 0 or more, more preferably 15 or more, still more preferably 30 or more. is there.

In addition, a viscous force acts as a resistance component against the elongation of the liquid bridge due to the movement of particles, and its size is proportional to the viscosity. Therefore, the viscosity of the granulating agent is not particularly limited as long as it is a liquid in the granulation step of granulating the raw material graphite, but it is preferably 1 cP or more in the granulation step. Further, the viscosity of the granulating agent at 25 ° C. is preferably 1 cP or more and 100,000 cP or less, more preferably 5 cP or more and 10000 cP or less, further preferably 10 cP or more and 8000 cP or less, and 50 cP or more and 6000 cP or less. Is particularly preferable. When the viscosity is within the above range, it is possible to prevent the adhered particles from being detached due to an impact force such as collision with the rotor or the casing when granulating the raw material carbon material.

Further, when the granulating agent used in the present invention contains an organic solvent, at least one of the organic solvents does not have a flash point, or when it has a flash point, the flash point is 5 ° C. or higher. .. As a result, it is possible to prevent the risk of ignition, fire, and explosion of the organic compound induced by impact or heat generation when granulating the raw material carbon material in the subsequent third step, so that the production is stable and efficient. Can be carried out.

Examples of the granulating agent used in the present invention include paraffin-based oils such as coal tar, petroleum-based heavy oil, and liquid paraffin, synthetic oils such as olefin-based oils, naphthen-based oils, and aromatic oils, and vegetable-based oils and fats. Natural oils such as animal aliphatics, esters and higher alcohols, organic compounds such as resin binder solutions in which a resin binder is dissolved in a solvent with a ignition point of 21 ° C or higher, aqueous solvents such as water, and their products. Examples include mixtures. As the resin binder, known ones can be used. For example, cellulose-based resin binders such as ethyl cellulose, methyl cellulose, and salts thereof, polymethyl acrylates, polyethyl acrylates, polybutyl acrylates, polyacrylic acids, and acrylic resin binders such as salts thereof, polymethyl methacrylate, and the like. A methacrylic resin binder such as polyethyl methacrylate or polybutyl methacrylate, a phenol resin binder, or the like can be used. Among the above, coal tar, petroleum-based heavy oil, paraffin-based oil such as liquid paraffin, and aromatic-based oil are preferable because they can produce a negative electrode material having a high degree of spheroidization and a small amount of fine powder.

The granulating agent preferably has properties that can be efficiently removed and do not adversely affect battery characteristics such as capacity, input / output characteristics, storage / cycle characteristics, and the like. Specifically, when heated to 700 ° C. in an inert atmosphere, the weight is usually reduced by 50% or more, preferably 80% or more, more preferably 95% or more, still more preferably 99% or more, and particularly preferably 99.9% or more. You can select what you want to do.

As a method of mixing the raw material carbon material and the granulating agent, for example, a method of mixing the raw material carbon material and the granulating agent using a mixer or a kneader, or a granulating agent in which an organic compound is dissolved in a low-viscosity dilution solvent. Examples thereof include a method of removing the diluting solvent after mixing the raw material carbon material. Further, when the raw material carbon material is granulated in the subsequent third step, the granulating agent and the raw material carbon material are put into the granulating apparatus, and the raw material carbon material and the granulating agent are mixed and granulated. There is also a method of performing the process at the same time.

The amount of the granulating agent added is preferably 0.1 part by weight or more, more preferably 1 part by weight or more, still more preferably 3 parts by weight or more, still more preferably 6 parts by weight or more with respect to 100 parts by weight of the raw material carbon material. More preferably 10 parts by weight or more, particularly preferably 12 parts by weight or more, most preferably 15 parts by weight or more, preferably 1000 parts by weight or less, more preferably 100 parts by weight or less, still more preferably 80 parts by weight or less. , Especially preferably 50 parts by weight or less, and most preferably 20 parts by weight or less. If it is within the above range, problems such as a decrease in the degree of spheroidization due to a decrease in the adhesive force between particles and a decrease in productivity due to the adhesion of the raw material carbon material to the apparatus are less likely to occur.

(Third step) Step of granulating the raw material carbon material The present invention is produced by a step of granulating the raw material carbon material by applying at least one of mechanical energy of impact, compression, friction, and shearing force. Is preferable. As an apparatus used in this step, for example, an apparatus can be used in which mechanical actions such as compression, friction, and shearing force including the interaction of raw material carbon materials are repeatedly applied mainly to an impact force.

Specifically, it has a rotor with a large number of blades installed inside the casing, and by rotating the rotor at high speed, it is a machine that impacts, compresses, frictions, shears, etc. with respect to the raw material carbon material introduced inside. A device that gives a specific action and performs surface treatment is preferable. Further, it is preferable that the material has a mechanism for repeatedly giving a mechanical action by circulating the raw material carbon material.
Examples of such a device include a hybridization system (manufactured by Nara Machinery Co., Ltd.), a cryptron, a cryptron orb (manufactured by EarthTechnica Co., Ltd.), a CF mill (manufactured by Ube Industries, Ltd.), a mechanofusion system, a novirta, and a faculty (manufactured by Ube Industries, Ltd.). Examples include Hosokawa Micron Co., Ltd.), Theta Composer (manufactured by Tokuju Kosakusho Co., Ltd.), COMPOSI (manufactured by Nippon Coke Industries Co., Ltd.), and the like. Of these, a hybridization system manufactured by Nara Machinery Co., Ltd. is preferable.

When processing using the above device, for example, the peripheral speed of the rotating rotor is preferably 30 m / sec or more, more preferably 50 m / sec or more, still more preferably 60 m / sec or more, particularly preferably 70 m / sec or more, most preferably. It is preferably 80 m / sec or more, and preferably 100 m / sec or less. Within the above range, it is preferable that fine powder can be more efficiently attached to the base material and encapsulated by the base material at the same time as spheroidization.
Further, the treatment of giving a mechanical action to the raw material carbon material can be performed by simply passing the raw material carbon material through, but it is preferable to carry out the treatment by circulating or retaining the raw material graphite in the apparatus for 30 seconds or more. The treatment is carried out by circulating or staying in the apparatus for preferably 1 minute or longer, more preferably 3 minutes or longer, and particularly preferably 5 minutes or longer.

Further, in the step of granulating the raw material carbon material, the raw material carbon material may be granulated in the presence of other substances, and the other substances include, for example, a metal that can be alloyed with lithium or an oxide thereof, or a non-carbon material. Crystalline carbon, raw coke and the like can be mentioned. By granulating together with a substance other than the raw material carbon material, it is possible to manufacture a negative electrode material for a non-aqueous secondary battery having various types of particle structures.

Further, the raw material carbon material, the granulating agent, and the other substances may be all charged into the apparatus, may be separately charged sequentially, or may be continuously charged. Further, the raw material carbon material, the granulating agent, and the other substances may be charged into the apparatus at the same time, mixed, or separately. The raw material carbon material, the granulating agent and the above-mentioned other substances may be mixed at the same time, the above-mentioned other substances may be added to the mixture of the raw material carbon material and the granulating agent, or the raw material carbon material and the granulating agent may be mixed with the other substances. The raw material carbon material may be added to the mixture of granules. It can be added and mixed separately at an appropriate timing according to the particle design.

(Fourth step) granulation carbon material, the granulated carbon material than crystallinity step present invention for impregnating a low carbonaceous material to further, granulating the carbonaceous material, further low crystallinity carbonaceous material than granulating the carbonaceous material It has a process of adhering. According to this step, it is possible to obtain a negative electrode material capable of suppressing side reactions with the electrolytic solution and improving rapid charge / discharge performance.
A composite carbon material in which a carbonaceous material with lower crystallinity than the granulated carbon material is added to the granulated carbon material is used.
It is sometimes called "carbonaceous composite carbon material").

In the treatment of adhering the carbonaceous material to the granulated carbon material, the organic compound to be the carbonaceous material and the granulated carbon material are mixed and heated in a non-oxidizing atmosphere, preferably under the circulation of nitrogen, argon, carbon dioxide, etc. It is a process of carbonizing or graphitizing an organic compound.

Specific organic compounds to be carbonaceous substances include various soft to hard coal tar pitches, carbon-based heavy oils such as coal liquefaction oil, and petroleum-based heavy oils such as crude oil at normal pressure or vacuum distillation residue oil. Various substances such as decomposition heavy oil, which is a by-product of ethylene production by naphtha decomposition, can be used.
Further, heat treatment pitches such as ethylene tar pitch, FCC decant oil, and Ashland pitch obtained by heat-treating the cracked heavy oil can be mentioned. Further, vinyl-based polymers such as polyvinyl chloride, polyvinyl acetate, polyvinyl butyral, and polyvinyl alcohol, substituted phenol resins such as 3-methylphenol formaldehyde resin and 3,5-dimethylphenol formaldehyde resin, and aromatics such as acenaphthylene, decacyclene, and anthracene. Examples thereof include hydrocarbons, nitrogen ring compounds such as phenadine and acrydin, and sulfur ring compounds such as thiophene. Examples of organic compounds that promote carbonization in the solid phase include natural polymers such as cellulose, chain vinyl resins such as polyvinylidene chloride and polyacrylonitrile, aromatic polymers such as polyphenylene, furfuryl alcohol resins, and phenols. Examples thereof include thermosetting resins such as formaldehyde resin and imide resin, and thermosetting resin raw materials such as furfuryl alcohol. Of these, petroleum-based heavy oils are preferable.

The heating temperature (calcination temperature) varies depending on the organic compound used for preparing the mixture, but is usually heated to 800 ° C. or higher, preferably 900 ° C. or higher, more preferably 950 ° C. or higher to sufficiently carbonize or graphitize. The upper limit of the heating temperature is a temperature at which the carbide of the organic compound does not reach a crystal structure equivalent to the crystal structure of natural graphite, and is usually at most 3500 ° C. The upper limit of the heating temperature is preferably 3000 ° C., preferably 2000 ° C., more preferably 1500 ° C.

After the above-mentioned treatment, it can be crushed and / or crushed to obtain a carbonaceous composite carbon material.
The shape is arbitrary, but the average particle size is usually 2 to 50 μm, preferably 5 to 35 μm, and particularly 8 to 30 μm. Crush and / or crush and / or classify as necessary so as to have the above particle size range.
The content of the carbonaceous material in the carbonaceous material composite carbon material is usually 0.01% by mass or more, preferably 0.1% by mass or more, and more preferably 0.3% or more with respect to the granulated carbon material as a raw material. , Especially preferably 0.7% by mass or more, and the content is usually 20% by mass or less, preferably 15% by mass or less, still more preferably 10% by mass or less, particularly preferably 7% by mass or less, most preferably. Is 5% by mass or less.

If the content of carbonaceous material in the carbonaceous material composite carbon material is too high, the negative electrode material will be damaged when rolling with sufficient pressure to achieve high capacity in a non-aqueous secondary battery. Destruction tends to occur, leading to an increase in irreversible charge / discharge capacity during the initial cycle and a decrease in initial efficiency.
On the other hand, if the content is too small, it tends to be difficult to obtain the effect of coating.

In addition, the content of carbonaceous material in the carbonaceous material composite carbon material can be calculated from the sample mass before and after firing the material as shown in the following formula. At this time, it is calculated assuming that there is no change in mass of the granulated carbon material before and after firing.

Carbon substance content (mass%) = [(w2-w1) / w1] × 100
(W1 is the mass of the granulated carbon material (kg), and w2 is the mass of the carbonaceous composite carbon material (kg))

(Other processes)
In the present invention, other steps may be appropriately performed before, after, or between the first step to the fourth step, if necessary.
-Step of removing the granulating agent In the present invention, there may be a step of removing the granulating agent. Examples of the method for removing the granulating agent include a method of cleaning with a solvent and a method of volatilizing / decomposing and removing the granulating agent by heat treatment.
The heat treatment temperature is preferably 60 ° C. or higher, more preferably 100 ° C. or higher, still more preferably 200 ° C. or higher, still more preferably 300 ° C. or higher, particularly preferably 400 ° C. or higher, most preferably 500 ° C. or higher, and preferably 1500 ° C. ° C. or lower, more preferably 1000 ° C. or lower, still more preferably 800 ° C. or lower. If it is within the above range, the granulating agent can be sufficiently volatilized, decomposed and removed, and the productivity can be improved.

The heat treatment time is preferably 0.5 to 48 hours, more preferably 1 to 40 hours, still more preferably 2 to 30 hours, and particularly preferably 3 to 24 hours. If it is within the above range, the granulating agent can be sufficiently volatilized, decomposed and removed, and the productivity can be improved.

The heat treatment atmosphere may be an active atmosphere such as an air atmosphere or an inert atmosphere such as a nitrogen atmosphere or an argon atmosphere. The heat treatment is not particularly limited when the heat treatment is performed at 200 ° C to 300 ° C, but the heat treatment is performed at 300 ° C or higher. From the viewpoint of preventing the surface of the carbon material from being oxidized, an inert atmosphere such as a nitrogen atmosphere or an argon atmosphere is preferable.

-Step of purifying the granulated carbon material In the present invention, there may be a step of purifying the granulated carbon material. Examples of a method for purifying the granulated carbon material include an acid treatment containing nitric acid and hydrochloric acid, which is a metal in the carbon material without introducing a sulfate which can be a highly active sulfur source into the system. It is preferable because impurities such as metal compounds and inorganic compounds can be removed.
For the above acid treatment, an acid containing nitric acid or hydrochloric acid may be used, and other acids such as bromine acid, hydrofluoric acid, boric acid or iodic acid, or citric acid, formic acid, acetic acid and shu An acid in which an organic acid such as an acid, trichloroacetic acid or trifluoroacetic acid is appropriately mixed can also be used. Concentrated hydrofluoric acid, concentrated nitric acid and concentrated hydrochloric acid are preferable, and concentrated nitric acid and concentrated hydrochloric acid are more preferable. In the present invention, graphite may be treated with sulfuric acid, but it is used in an amount and concentration that does not impair the effects and physical characteristics of the present invention.

When a plurality of acids are used, for example, a combination of hydrofluoric acid, nitric acid, and hydrochloric acid is preferable because the above impurities can be efficiently removed. When the types of acids are combined as described above, the mixing ratio of the mixed acids is usually 10% by mass or more, preferably 20% by mass or more, and more preferably 25% by mass or more. The upper limit is a value that is a mixture of all equal amounts (represented by 100% by mass / type of acid).

The mixing ratio (mass ratio) of graphite and acid in the acid treatment is usually 100:10 or more, preferably 100:20 or more, more preferably 100:30 or more, still more preferably 100:40 or more, and 100. : 1000 or less, preferably 100: 500 or less, more preferably 100: 300 or less.

The acid treatment is performed by immersing the carbon material in the acidic solution as described above. The immersion time is usually 0.5 to 48 hours, preferably 1 to 40 hours, more preferably 2 to 30, and even more preferably 3 to 24 hours.
The immersion temperature is usually 25 ° C. or higher, preferably 40 ° C. or higher, more preferably 50 ° C. or higher, still more preferably 60 ° C. or higher. When an aqueous acid is used, the theoretical upper limit is 100 ° C., which is the boiling point of water.

It is preferable to carry out further water washing for the purpose of removing the acid content remaining by the acid washing and raising the pH from weakly acidic to the neutral range. For example, if the pH of the treated graphite is usually 3 or more, preferably 3.5 or more, more preferably 4 or more, still more preferably 4.5 or more, washing with water can be omitted, and if the above range If not, it is preferable to wash with water if necessary. It is preferable to use ion-exchanged water or distilled water as the cleaning water from the viewpoint of improving cleaning efficiency and preventing impurities from being mixed. The specific resistance, which is an index of the amount of ions in water, is usually 0.1 MΩ · cm or more, preferably 1 MΩ · cm or more, more preferably 10 MΩ · cm or more. The theoretical upper limit at 25 ° C. is 18.24 MΩ · cm.

The time for washing with water, that is, stirring the treated graphite and water is usually 0.5 to 48 hours, preferably 1 to 40 hours, more preferably 2 to 30 hours, still more preferably 3 to 24 hours. is there.
The mixing ratio of the treated carbon material and water is usually 100:10 or more, preferably 100:30 or more, more preferably 100:50 or more, still more preferably 100: 100 or more, and 100: 1000 or less. , Preferably 100: 700 or less, more preferably 100: 500 or less, still more preferably 100: 400 or less.

The stirring temperature is usually 25 ° C. or higher, preferably 40 ° C. or higher, more preferably 50 ° C. or higher, still more preferably 60 ° C. or higher. The upper limit is 100 ° C., which is the boiling point of water. When the water cleaning treatment is performed in a batch manner, it is preferable to repeat the stirring-filtration treatment step in pure water a plurality of times for cleaning from the viewpoint of removing impurities and acids. The above treatment may be repeated so that the pH of the above-mentioned treated carbon material is within the above range. Usually, it is once or more, preferably twice or more, and more preferably three times or more.

By performing the treatment as described above, the wastewater ion concentration of the obtained carbon material is usually 200 ppm or less, preferably 100 ppm or less, more preferably 50 ppm or less, further preferably 30 ppm or less, and usually 1 ppm or more, preferably 2 ppm. As mentioned above, it is more preferably 3 ppm or more, still more preferably 4 ppm or more.

-Step of heat-treating the granulated carbon material In the present invention, a step of heat-treating may be provided in order to adjust the unstable carbon amount and crystallinity of the granulated carbon material.
When the above-mentioned granulation treatment is performed, the anxious low carbon amount on the surface of the carbon material particles may increase too much, and the anxious low carbon amount can be appropriately reduced by performing the heat treatment.
The temperature conditions during the heat treatment are not particularly limited, but are usually 300 ° C. or higher, preferably 500 ° C., more preferably 700 ° C., particularly preferably 800 ° C. or higher, and usually 2000 ° C., depending on the desired degree of crystallinity. The temperature is in the range of ° C. or lower, preferably 1500 ° C. or lower, particularly preferably 1200 ° C. or lower. Under the above temperature conditions, the crystallinity of the surface of the carbon material particles can be appropriately increased.
Further, when the granulated carbon material contains a carbon material having low crystallinity, it is possible to increase the crystallinity by graphitizing the carbon material having low crystallinity in this step for the purpose of increasing the discharge capacity. The temperature conditions during the heat treatment are not particularly limited, but are usually 600 ° C. or higher, preferably 900 ° C., more preferably 1600 ° C., particularly preferably 2500 ° C. or higher, and usually 3200 ° C., depending on the desired degree of crystallinity. The temperature is in the range of ° C. or lower, preferably 3100 ° C. or lower. Under the above temperature conditions, the crystallinity of the surface of the carbon material particles can be enhanced.
When the heat treatment is performed, the holding time for keeping the temperature condition in the above range is not particularly limited, but is usually longer than 10 seconds and 72 hours or less.
The heat treatment is carried out in an atmosphere of an inert gas such as nitrogen gas or in a non-oxidizing atmosphere of a gas generated from the raw material graphite. The apparatus used for the heat treatment is not particularly limited, and for example, a shuttle furnace, a tunnel furnace, an electric furnace, a reed hammer furnace, a rotary kiln, a direct energization furnace, an Achison furnace, a resistance heating furnace, an induction heating furnace and the like can be used.

[Mixing of carbon materials]
Further, in the present invention, for the purpose of improving the orientation of the electrode plate, the permeability of the electrolytic solution, the conductive path, etc., and improving the cycle characteristics, the swelling of the electrode plate, etc., a carbon material different from the granulated carbon material is mixed. (Hereinafter, a carbon material obtained by mixing the granulated carbon material with a carbon material different from the granulated carbon material may be referred to as a "mixed carbon material").
Examples of the carbon material different from the carbon material include natural graphite, artificial graphite, coated graphite in which the carbon material is coated with a carbonaceous material, amorphous carbon, and a material selected from carbon materials containing metal particles and metal compounds. Can be used. Any one of these materials may be used alone, or two or more of these materials may be used in any combination and composition.

As the natural graphite, for example, a highly purified carbon material or a spherical natural graphite can be used. Purification as used in the present invention usually means ash content contained in low-purity natural graphite by treating with an acid such as hydrochloric acid, sulfuric acid, nitric acid, or phosphoric acid, or by performing a combination of a plurality of acid treatment steps. It means an operation of dissolving and removing metal and the like, and usually, the acid content used in the high purification treatment step is removed by performing a water washing treatment or the like after the acid treatment step. Further, ash, metals and the like may be evaporated and removed by treating at a high temperature of 2000 ° C. or higher instead of the acid treatment step. Further, ash, metals and the like may be removed by treating with a halogen gas atmosphere such as chlorine gas at the time of high temperature heat treatment. Furthermore, these methods may be used in any combination.

The volume-based average particle size of natural graphite is usually in the range of 5 μm or more, preferably 8 μm or more, more preferably 10 μm or more, particularly preferably 12 μm or more, and usually 60 μm or less, preferably 40 μm or less, particularly preferably 30 μm or less. .. When the average particle size is in this range, high-speed charge / discharge characteristics and processability are good, which is preferable.
The BET specific surface area of natural graphite is usually in the range of 1 m ² / g or more, preferably 2 m ² / g or more, and usually 30 m ² / g or less, preferably 15 m ² / g or less. When the specific surface area is in this range, high-speed charge / discharge characteristics and processability are good, which is preferable.
The tap density of natural graphite is usually 0.6 g / cm ³ or more, 0.7 g / cm ³ or more, more preferably 0.8 g / cm ³ or more, and even more preferably 0.85 g / cm ³ or more. Further, usually 1.3 g / cm ³ or less, 1.2 g / cm ³ or less is preferable, and 1.1 g / cm ³ or less is more preferable. Within this range, high-speed charge / discharge characteristics and processability are good, which is preferable.

Examples of artificial graphite include particles obtained by graphitizing a carbon material. For example, single graphite precursor particles are calcined in the form of powder, graphitized particles, or a plurality of graphite precursor particles are molded and calcined. Graphitized and crushed granulated particles can be used.
The volume-based average particle size of the artificial graphite is usually in the range of 5 μm or more, preferably 10 μm or more, and usually 60 μm or less, preferably 40 μm, and more preferably 30 μm or less. Within this range, swelling of the electrode plate is suppressed and processability is improved, which is preferable.
The BET specific surface area of artificial graphite is usually 0.5 m ² / g or more, preferably 1.0 m ² / g or more, and usually 8 m ² / g or less, preferably 6 m ² / g or less, more preferably 4 m 2 / g. The range is as follows. Within this range, swelling of the electrode plate is suppressed and processability is improved, which is preferable.

The tap density of the artificial graphite is usually 0.6 g / cm ³ or more, 0.7 g / cm ³ or more, more preferably 0.8 g / cm ³ or more, and even more preferably 0.85 g / cm ³ or more. In addition, usually 1.5 g / cm ³ or less, 1.4 g / cm ³ or less is preferable, and 1.3 g / cm ³ or less is more preferable. Within this range, swelling of the electrode plate is suppressed and processability is improved, which is preferable.

Examples of the coated graphite in which the carbon material is coated with a carbonaceous material include particles obtained by coating, calcining and / or graphitizing an organic compound which is a precursor of the above-mentioned carbonaceous material on natural graphite or artificial graphite, or natural graphite or artificial graphite. Particles coated with a carbonaceous material by CVD can be used.

The volume-based average particle size of the coated graphite is usually in the range of 5 μm or more, preferably 8 μm or more, more preferably 10 μm or more, particularly preferably 12 μm or more, and usually 60 μm or less, preferably 40 μm or less, particularly preferably 30 μm or less. .. When the average particle size is in this range, high-speed charge / discharge characteristics and processability are good, which is preferable.
The BET specific surface area of the coated graphite is usually 1 m ² / g or more, preferably 2 m ² / g or more, more preferably 2.5 m ² / g or more, and usually 20 m ² / g or less, preferably 10 m ² / g or less. More preferably, it is in the range of 8 m ² / g or less, and particularly preferably in ^{the range of 5 m 2} / g or less. When the specific surface area is in this range, high-speed charge / discharge characteristics and processability are good, which is preferable.

The tap density of the coated graphite is usually 0.6 g / cm ³ or more, 0.7 g / cm ³ or more, more preferably 0.8 g / cm ³ or more, and even more preferably 0.85 g / cm ³ or more. Further, usually 1.3 g / cm ³ or less, 1.2 g / cm ³ or less is preferable, and 1.1 g / cm ³ or less is more preferable. When the tap density is in this range, high-speed charge / discharge characteristics and processability are good, which is preferable.

As the amorphous carbon, for example, particles obtained by calcining bulk mesophase or particles obtained by insolubilizing an easily graphitizing organic compound and calcining can be used.
The volume-based average particle size of amorphous carbon is usually in the range of 5 μm or more, preferably 12 μm or more, and usually 60 μm or less, preferably 40 μm or less. Within this range, high-speed charge / discharge characteristics and processability are good, which is preferable.
BET specific surface area of the amorphous carbon is usually ^{1 m} 2 / g or more, preferably ^2m 2 / g or more, more preferably 2.5 m ² / g or more and usually ^8m 2 / g or less, preferably ^{6 m} 2 / The range is g or less, more preferably 4 m ² / g or less. When the specific surface area is in this range, high-speed charge / discharge characteristics and processability are good, which is preferable.

The tap density of amorphous carbon is usually 0.6 g / cm ³ or more, 0.7 g / cm ³ or more, more preferably 0.8 g / cm ³ or more, and further preferably 0.85 g / cm ³ or more. preferable. Further, usually 1.3 g / cm ³ or less, 1.2 g / cm ³ or less is preferable, and 1.1 g / cm ³ or less is more preferable. When the tap density is in this range, high-speed charge / discharge characteristics and processability are good, which is preferable.

Carbon materials containing metal particles and metal compounds include, for example, Fe, Co, Sb, Bi, Pb, Ni, Ag, Si, Sn, Al, Zr, Cr, P, S, V, Mn, Nb, Mo, Cu, Z
Examples thereof include a metal selected from the group consisting of n, Ge, In, Ti and the like, or a material in which a compound thereof is composited with graphite. As the metal or a compound thereof that can be used, an alloy composed of two or more kinds of metals may be used, and the metal particles may be alloy particles formed by two or more kinds of metal elements. Among these, a metal selected from the group consisting of Si, Sn, As, Sb, Al, Zn and W or a compound thereof is preferable, and Si and SiOx are particularly preferable. This general formula SiOx is obtained by using silicon dioxide (SiO2) and metallic Si (Si) as raw materials, and the value of x is usually 0 <x <2, preferably 0.2 or more and 1.8 or less. , More preferably 0.4 or more and 1.6 or less, still more preferably 0.6 or more and 1.4 or less. Within this range, it is possible to reduce the irreversible capacity due to the combination of Li and oxygen at the same time as having a high capacity.
From the viewpoint of cycle life, the volume-based average particle size of the metal particles is usually 0.005 μm or more, preferably 0.01 μm or more, more preferably 0.02 μm or more, still more preferably 0.03 μm or more, and usually 10 μm or less. It is preferably 9 μm or less, more preferably 8 μm or less. When the average particle size is in this range, the volume expansion due to charge / discharge is reduced, and good cycle characteristics can be obtained while maintaining the charge / discharge capacity.
The BET specific surface area of the metal particles is usually preferably 0.5 m ² / g or more and 120 m ² / g or less, 1 m ² / g or more and 100 m ² / g or less. When the specific surface area is within the above range, the charge / discharge efficiency and discharge capacity of the battery are high, lithium is taken in and out quickly in high-speed charge / discharge, and the rate characteristics are excellent, which is preferable.

The device used for mixing the granulated carbon material and a carbon material different from the granulated carbon material is not particularly limited, but for example, in the case of a rotary mixer: a cylindrical mixer, a twin cylindrical mixer. For machines, double conical mixers, cubic mixers, stag beetle mixers, fixed mixers: spiral mixers, ribbon mixers, Muller mixers, Helical Flit mixers,
A Pugmill type mixer, a fluidization type mixer and the like can be used.

<Physical characteristics of carbon materials for non-aqueous secondary batteries>
The carbon material of the present invention contains a carbonaceous substance on the surface of the granulated carbon material and satisfies the relationship of the following formula 1.
(Equation 1)
(DTA [μV] at the first peak) / (DTA [μV] at the second peak) ≧
0.4

If the relationship represented by the above formula 1 is not satisfied, the Li ion insertion / desorption site becomes insufficient, and the low temperature input / output characteristics tend to deteriorate. The method for measuring each physical property used in the calculation of the above formula (1) will be described later.

The carbon material of the present invention is not particularly limited as long as it satisfies the above formula (1). Hereinafter, preferable physical properties of the carbon material of the material of the present invention will be described.

・ BET specific surface area (SA)
The specific surface area (SA) of the carbon material of the present invention measured by the BET method is usually 1 m ² / g or more.
It is preferably 2 m ² / g or more, more preferably 2.5 m ² / g or more, still more preferably 4 m ^{2 or more.}
/ G or more, most preferably 5 m ² / g or more, most preferably 6 m ² / g or more. Further, preferably 30 m ² / g or less, more preferably 20 m ² / g or less, still more preferably 10
It is m ² / g or less. If the specific surface area is within the above range, excellent high-speed charge-discharge characteristic output characteristics it is possible to sufficiently secure a site where Li is out, since the activity can be suppressed moderately against the electrolyte of the active material, the initial irreversible There is a tendency that high-capacity batteries can be manufactured without increasing the capacity.

Further, when a negative electrode is formed by using a carbon material, an increase in reactivity with the electrolytic solution can be suppressed and gas generation can be suppressed, so that a preferable non-aqueous secondary battery can be provided. The BET specific surface area is determined by using a surface area meter (for example, a specific surface area measuring device "AMS8000" manufactured by Okura Riken Co., Ltd.) to perform preliminary vacuum drying at 100 ° C. for 3 hours under nitrogen flow on a carbon material sample, and then the liquid nitrogen temperature. It is defined as a value measured by the nitrogen adsorption BET method by the gas flow method using a nitrogen helium mixed gas that has been cooled to the above and accurately adjusted so that the value of the relative pressure of nitrogen with respect to the atmospheric pressure is 0.3.

-TG-DTA measurement The carbon material of the present invention is DTA (Differential) obtained when TG-DTA measurement is performed.
The Thermal Analysis) curve has a first peak on the relatively low temperature side and a second peak on the relatively high temperature side in the range of 500 ° C. or higher and 1000 ° C. or lower. It is considered that the first peak on the relatively low temperature side in the range of 500 ° C. or higher and 1000 ° C. or lower is mainly derived from the combustion of the low crystalline carbonaceous material component. Further, it is considered that the second peak on the relatively high temperature side is mainly derived from the combustion of graphite constituting the granulated carbon material. The ratio of the first peak to the second peak of the carbon material of the present invention is higher than that of the conventional carbon material containing a carbonaceous substance on the surface of graphite particles. It is considered that this is because a carbonaceous material component having a high specific surface area and low crystallinity is sufficiently present.
Therefore, the ratio of the first peak to the second peak of the carbon material of the present invention "(DTA [μV] at the first peak) / (DTA [μV] at the second peak)" is usually 0.5. As mentioned above, it is more preferably 0.7 or more, further preferably 0.8 or more, and particularly preferably 0.9 or more. Further, it is usually 3.0 or less, preferably 2.5 or less, and more preferably 2.0 or less.
The TG-DTA measurement can be performed by the method described in the examples.

-Volume-based average particle size (d50)
The volume-based average particle diameter (also referred to as “d50”) of the carbon material of the present invention is preferably 1 μm or more, more preferably 5 μm or more, still more preferably 8 μm or more. The average particle size d50 is usually 50 μm or less, preferably 40 μm or less, more preferably 35 μm or less, still more preferably 30 μm or less, and particularly preferably 25 μm or less. If the average particle size d50 is too small, the irreversible capacity of the non-aqueous secondary battery obtained by using the carbon material tends to increase and the initial battery capacity tends to be lost. On the other hand, if the average particle size d50 is too large, the slurry is applied. In some cases, process inconveniences such as streaks may occur, high current density charge / discharge characteristics may deteriorate, and low temperature input / output characteristics may deteriorate.

Further, in the present specification, the average particle size d50 is a carbon material in 10 mL of a 0.2 mass% aqueous solution of polyoxyethylene sorbitan monolaurate (for example, Tween 20 (registered trademark)) which is a surfactant. 0.01 g was suspended, and this was introduced as a measurement sample into a commercially available laser diffraction / scattering particle size distribution measuring device (for example, LA-920 manufactured by HORIBA), and the measurement sample was irradiated with 28 kHz ultrasonic waves at an output of 60 W for 1 minute. After that, it is defined as the one measured as the volume-based median diameter in the measuring device.

-True Density The true density of the carbon material of the present invention is preferably 1.9 g / cm ³ or more, more preferably 2 g / cm.
cm ³ or more, more preferably 2.1 g / cm ³ or more, particularly preferably 2.2 g / cm ³ or more, the upper limit is 2.26 g / cm ^3. The upper limit is the theoretical value of graphite.

When the true density is within the above range, a structure having low crystallinity in which Li ions are easily inserted and removed can be appropriately obtained, so that good input / output characteristics can be obtained.
True density is defined as measured by the liquid phase substitution method (pycnometer method) using butanol.

-Tap density The tap density of the carbon material of the present invention is usually 0.75 g / cm ³ or more, more preferably 0.8 g / cm ³ or more, still more preferably 0.85 g / cm ³ or more, and particularly preferably 0.90 g / cm. It is cm ³ or more, preferably 1.3 g / cm ³ or less, more preferably 1.2 g / cm ³ or less, and further preferably 1.1 g / cm ³ or less.

When the tap density is within the above range, the processability such as streaking at the time of producing the electrode plate is improved, and the high-speed charge / discharge characteristics are excellent. Further, since the carbon density in the particles does not easily increase, the rollability is good, and it tends to be easy to form a high-density negative electrode sheet.
For the tap density, the carbon material of the present invention was dropped into a cylindrical tap cell having a diameter of 1.6 cm and a volume capacity of 20 cm ^{3 through a sieve having a mesh size of 300 μm using a powder density measuring device, and the cell was fully filled.} After that, tapping with a stroke length of 10 mm is performed 1000 times, and the density is defined as the density obtained from the volume at that time and the mass of the sample.

Raman R value The Raman R value represented by the following formula 1 of the carbon material of the present invention is usually 0.01 or more, preferably 0.1 or more, more preferably 0.2 or more, still more preferably 0.25 or more. , Especially preferably 0.3 or more, and most preferably 0.35 or more. The upper limit of the Raman R value is not particularly limited, but is usually 1 or less, preferably 0.7 or less, more preferably 0.6 or less, and further preferably 0.5 or less.

Intensity _{I A} of the intensity _I B / 1580 cm-1 near the peak _{P A} of the peak _{P B} in the vicinity of 1360 cm ^-1 in equation 1 Raman value R = Raman spectroscopy
Incidentally, the scope of 1580～1620Cm ^-1 A "1580cm around ^-1" in the present specification, "1360cm around ^-1" refers to the range of 1350 ^-1.

When the Raman R value is within the above range, the crystallinity of the carbon material particle surface is appropriate, so that sufficient Li ion insertion / desorption sites can exist, so that the carbon material has good low-temperature input / output characteristics and discharge capacity. Tends to be obtained.

The Raman spectrum can be measured with a Raman spectroscope. Specifically, the sample is filled by naturally dropping the measurement target particle into the measurement cell, and while irradiating the measurement cell with an argon ion laser light, the measurement cell is rotated in a plane perpendicular to the laser light. Make a measurement. The measurement conditions are as follows.

Wavelength of argon ion laser light: 514.5 nm
Laser power on sample: 25 mW
Resolution: 4 cm ^-1
Measuring range: 1100 cm ^{-1 to} 1730 ^{cm -1}
Peak intensity measurement, peak half width measurement: background processing, smoothing processing (convolution 5 points by simple average)

-Circularity The circularity of the carbon material of the present invention is 0.88 or more, preferably 0.90 or more, more preferably 0.91 or more, and further preferably 0.92 or more. The circularity is preferably 1 or less.
It is more preferably 0.98 or less, still more preferably 0.97 or less. When the circularity is within the above range, the deterioration of the high current density charge / discharge characteristics of the non-aqueous secondary battery tends to be suppressed. The circularity is defined by the following equation, and when the circularity is 1, it becomes a theoretical true sphere.
When circularity is within the above range, L i ion diffusion tortuosity is lowered electrolyte movement in interparticle voids become smooth, and moderately since it is possible to contact between carbon material, good It tends to show rapid charge / discharge characteristics and cycle characteristics.

Circularity = (perimeter of a corresponding circle having the same area as the projected particle shape) / (actual perimeter of the projected particle shape)

As the value of circularity, for example, a flow-type particle image analyzer (for example, FPIA manufactured by Sysmex Industrial Co., Ltd.) is used, and about 0.2 g of a sample (carbon material) is used as a surfactant, polyoxyethylene (20) sorbitan. After dispersing in a 0.2 mass% aqueous solution of monolaurate (about 50 mL) and irradiating the dispersion with 28 kHz ultrasonic waves at an output of 60 W for 1 minute, the detection range was specified as 0.6 to 400 μm, and the particle size was changed. Use the values measured for particles in the range of 1.5-40 μm.

X-ray parameters The d value (interlayer distance) of the lattice planes (002 planes) of the carbon material of the present invention determined by X-ray diffraction by the Gakushin method is preferably 0.335 nm or more and less than 0.340 nm. Here, the d value is more preferably 0.339 nm or less, still more preferably 0.337 nm or less. When the d002 value is within the above range, the crystallinity of graphite is high, so that the initial irreversible capacity tends to suppress the increase. Here, 0.335 nm is a theoretical value of graphite.

The crystallite size (Lc) of the carbon material determined by X-ray diffraction by the Gakushin method is preferably in the range of 1.5 nm or more, more preferably 3.0 nm or more. Within the above range, the particles have not too low crystallinity, and the reversible capacity is unlikely to decrease when a non-aqueous secondary battery is used. The lower limit of Lc is the theoretical value of graphite.

<Negative electrode for non-aqueous secondary batteries>
The negative electrode for a non-aqueous secondary battery of the present invention (hereinafter, also appropriately referred to as an “electrode sheet”) includes a current collector and a negative electrode active material layer formed on the current collector, and the active material layer is at least. It is characterized by containing the carbon material of the present invention. More preferably, it contains a binder.
As the binder, one having an olefinically unsaturated bond in the molecule is used. The type is not particularly limited, and specific examples thereof include styrene-butadiene rubber, styrene / isoprene / styrene rubber, acrylonitrile-butadiene rubber, butadiene rubber, and ethylene / propylene / diene copolymer. By using a binder having such an olefinically unsaturated bond, the swelling property of the active material layer with respect to the electrolytic solution can be reduced. Of these, styrene-butadiene rubber is preferable because of its availability.

By using a binder having such an olefinically unsaturated bond in combination with the above-mentioned active material, the strength of the negative electrode plate can be increased. When the strength of the negative electrode is high, deterioration of the negative electrode due to charging and discharging is suppressed, and the cycle life can be extended. Further, in the negative electrode according to the present invention, since the adhesive strength between the active material layer and the current collector is high, even if the binder content in the active material layer is reduced, when the negative electrode is wound to manufacture a battery. It is presumed that the problem of the active material layer peeling off from the current collector does not occur.

As the binder having an olefinically unsaturated bond in the molecule, it is desirable that the binder has a large molecular weight or a large proportion of unsaturated bonds. Specifically, in the case of a binder having a large molecular weight, the weight average molecular weight is preferably in the range of 10,000 or more, more preferably 50,000 or more, preferably 1 million or less, and more preferably 300,000 or less. Is desirable. In the case of a binder having a large proportion of unsaturated bonds, the number of moles of olefinically unsaturated bonds per gram of all binders is preferably 2.5 × 10 ⁻⁷ mol or more, more preferably 8 × 10 ^{−. 7} mol or more, preferably 1 × ^10-6 mol or less, more preferably 5 × 1
0 ^-6 mol those in the following ranges is desirable. The binder may satisfy at least one of these molecular weight regulations and unsaturated bond ratio regulations, but it is more preferable that both regulations are satisfied at the same time. When the molecular weight of the binder having an olefinically unsaturated bond is within the above range, the mechanical strength and flexibility are excellent.

The binder having an olefinically unsaturated bond has a degree of unsaturation of preferably 15% or more, more preferably 20% or more, further preferably 40% or more, and preferably 90% or less, more preferably 80. % Or less. The degree of unsaturation represents the ratio (%) of double bonds to the repeating unit of the polymer.
In the present invention, a binder having no olefinically unsaturated bond can also be used in combination with the above-mentioned binder having an olefinically unsaturated bond as long as the effect of the present invention is not lost. The mixing ratio of the binder having no olefinically unsaturated bond to the binder having an olefinically unsaturated bond is preferably in the range of 150% by mass or less, more preferably 120% by mass or less.

The coatability can be improved by using a binder having no olefinically unsaturated bond in combination, but if the amount used in combination is too large, the strength of the active material layer decreases.
Examples of binders having no olefinic unsaturated bond include thickening polysaccharides such as methyl cellulose, carboxymethyl cellulose, starch, caraginan, purulan, guar gum, and zansan gum (xanthan gum), and polyethers such as polyethylene oxide and polypropylene oxide. Vinyl alcohols such as polyvinyl alcohol and polyvinyl butyral, polyacids such as polyacrylic acid and polymethacrylic acid, metal salts of these polymers, fluoropolymers such as polyvinylidene fluoride, alcan polymers such as polyethylene and polypropylene, and theirs. Examples include copolymers.

When the carbon material of the present invention is used in combination with the above-mentioned binder having an olefinically unsaturated bond, the ratio of the binder used for the active material layer can be reduced as compared with the conventional one. Specifically, the carbon material of the present invention and a binder (in some cases, this may be a mixture of a binder having an unsaturated bond and a binder having no unsaturated bond as described above). The mass ratio of is preferably 90/10 or more, more preferably 95/5 or more, preferably 99.9 / 0.1 or less, and more preferably 99.5 / 0.5 in each dry mass ratio. The range is as follows. When the ratio of the binder is within the above range, the decrease in capacity and the increase in resistance can be suppressed, and the strength of the electrode plate is also excellent.

The negative electrode of the present invention is formed by dispersing the above-mentioned carbon material of the present invention and a binder in a dispersion medium to form a slurry, and applying this to a current collector. As the dispersion medium, an organic solvent such as alcohol or water can be used. If desired, a conductive agent may be added to this slurry. Examples of the conductive agent include carbon black such as acetylene black, ketjen black and furnace black, Cu and Ni having an average particle size of 1 μm or less, and fine powder made of an alloy thereof. The amount of the conductive agent added is preferably about 10% by mass or less with respect to the carbon material of the present invention.

As the current collector to which the slurry is applied, a conventionally known current collector can be used. Specific examples thereof include metal thin films such as rolled copper foil, electrolytic copper foil, and stainless steel foil. The thickness of the current collector is preferably 4 μm or more, more preferably 6 μm or more, preferably 30 μm or less, and more preferably 20 μm or less.
After applying the slurry on the current collector, the temperature is preferably 60 ° C. or higher, more preferably 80 ° C. or higher, and preferably 200 ° C. or lower, more preferably 195 ° C. or lower, under dry air or an inert atmosphere. It dries and forms an active layer.

The thickness of the active material layer obtained by applying and drying the slurry is preferably 5 μm or more, more preferably 20 μm or more, further preferably 30 μm or more, preferably 200 μm or less, more preferably 100 μm or less, still more preferably. It is 75 μm or less. When the thickness of the active material layer is within the above range, it is excellent in practicality as a negative electrode in consideration of the particle size of the active material, and a sufficient Li storage / release function for a high-density current value can be obtained. ..

The density of the carbon material in the active material layer varies depending on the application, but in applications where capacity is important, it is preferably 1.30 g / cm ³ or more, more preferably 1.35 g / cm ³ or more, and further preferably 1.40 g / cm. It is cm ³ or more, particularly preferably 1.50 g / cm ³ or more. Further, it is preferably 1.9 g / cm ³ or less. When the density is within the above range, the capacity of the battery per unit volume can be sufficiently secured, and the rate characteristics are less likely to deteriorate.

When the negative electrode for a non-aqueous secondary battery is produced using the carbon material of the present invention described above, the method and selection of other materials are not particularly limited. Further, even when a lithium ion secondary battery is manufactured using this negative electrode, the selection of members necessary for the battery configuration such as the positive electrode and the electrolytic solution constituting the lithium ion secondary battery is not particularly limited. Hereinafter, the details of the negative electrode for a lithium ion secondary battery and the lithium ion secondary battery using the carbon material of the present invention will be illustrated, but the materials that can be used, the manufacturing method, and the like are not limited to the following specific examples. Absent.

<Non-water secondary battery>
The basic configuration of the non-aqueous secondary battery of the present invention, particularly a lithium ion secondary battery, is the same as that of a conventionally known lithium ion secondary battery, and usually has a positive electrode and a negative electrode capable of occluding and releasing lithium ions, and an electrolyte. To be equipped. As the negative electrode, the negative electrode of the present invention described above is used.
The positive electrode is formed by forming a positive electrode active material layer containing a positive electrode active material and a binder on a current collector.

Examples of the positive electrode active material include metal chalcogen compounds that can occlude and release alkali metal cations such as lithium ions during charging and discharging. Metallic chalcogen compounds include transition metal oxides such as vanadium oxide, molybdenum oxide, manganese oxide, chromium oxide, titanium oxide, and tungsten oxide, vanadium sulfide, and molybdenum sulfide. things, sulfides of titanium, transition metal sulfides such as _CuS, NIPS 3, FEPS phosphorus transition metals, such as ₃ - sulfur _compounds, VSe 2, selenium compounds of transition metals such as NbSe _{3, Fe 0.25} V _0. Examples thereof include composite oxides of transition metals such as ₇₅ S ₂ and Na _0.1 CrS _2, and composite sulfides of transition metals such as _{LiCo S 2} and LiNi S _2.

Among _{these, V 2 O 5, V 5} O 13, VO 2, Cr 2 O 5, MnO 2, TiO 2, MoV 2 O 8, LiCoO 2, LiNiO 2, LiMn 2 O 4, TiS 2, V 2 S ₅ , Cr _0.25 V _0.75 S ₂ , Cr _0.5 V _0.5 S _2, etc. are preferable, and LiCoO ₂ , LiNiO ₂ , LiMn ₂ O ₄ and some of these transition metals are particularly preferable. Is a lithium transition metal composite oxide in which is replaced with another metal. These positive electrode active materials may be used alone or in combination of two or more.

As the binder for binding the positive electrode active material, a known binder can be arbitrarily selected and used. Examples include inorganic compounds such as silicate and water glass, and resins having no unsaturated bond such as Teflon (registered trademark) and polyvinylidene fluoride. Of these, a resin having no unsaturated bond is preferable. If a resin having an unsaturated bond is used as the resin for binding the positive electrode active material, it may be decomposed during the oxidation reaction. The weight average molecular weight of these resins is usually in the range of 10,000 or more, preferably 100,000 or more, and usually 3 million or less, preferably 1 million or less.

A conductive material may be contained in the positive electrode active material layer in order to improve the conductivity of the electrode. The conductive agent is not particularly limited as long as it can be mixed with an active material in an appropriate amount to impart conductivity, but usually, carbon powder such as acetylene black, carbon black, and graphite, various metal fibers, powder, and foil are used. And so on.
The positive electrode plate is formed by slurrying a positive electrode active material or a binder with a solvent, applying it on a current collector, and drying it in the same manner as in the production of the negative electrode as described above. Aluminum, nickel, stainless steel (SUS) and the like are used as the current collector of the positive electrode, but the current collector is not limited in any way.

As the electrolyte, a non-aqueous electrolyte solution in which a lithium salt is dissolved in a non-aqueous solvent, or a gel-like, rubber-like, or solid sheet-like electrolyte obtained by dissolving this non-aqueous electrolyte solution in an organic polymer compound or the like is used.
The non-aqueous solvent used for the non-aqueous electrolyte solution is not particularly limited, and can be appropriately selected and used from known non-aqueous solvents that have been conventionally proposed as solvents for the non-aqueous electrolyte solution. For example, chain carbonates such as diethyl carbonate, dimethyl carbonate and ethyl methyl carbonate; cyclic carbonates such as ethylene carbonate, propylene carbonate and butylene carbonate; chain ethers such as 1,2-dimethoxyethane; tetrahydrofuran, 2-methyl. Cyclic ethers such as tetrahydrofuran, sulfolane and 1,3-dioxolane; chain esters such as methyl formate, methyl acetate and methyl propionate; cyclic esters such as γ-butyrolactone and γ-valerolactone.

Any one of these non-aqueous solvents may be used alone, or two or more thereof may be mixed and used. In the case of a mixed solvent, a combination of a mixed solvent containing a cyclic carbonate and a chain carbonate is preferable, and when the cyclic carbonate is a mixed solvent of ethylene carbonate and propylene carbonate, high ionic conductivity can be exhibited even at a low temperature, and low-temperature charging is performed. It is particularly preferable in that the non-characteristics are improved. Among them, propylene carbonate is preferably in the range of 2% by mass or more and 80% by mass or less, more preferably in the range of 5% by mass or more and 70% by mass or less, and further in the range of 10% by mass or more and 60% by mass or less with respect to the whole non-aqueous solvent. preferable. If the proportion of propylene carbonate is lower than the above, the ionic conductivity at low temperature decreases, and if the proportion of propylene carbonate is higher than the above, propylene carbonate solvated with lithium ions moves between the graphite phases when a graphite-based electrode is used. The co-insertion causes delamination deterioration of the graphite-based negative electrode active material, and there is a problem that a sufficient capacity cannot be obtained.

The lithium salt used in the non-aqueous electrolyte solution is not particularly limited, and can be appropriately selected and used from known lithium salts known to be usable for this purpose. For example, halides such as LiCl, LiBr, perhalonates _{such as LiClO 4 , LiBrO 4} , LiClO ₄ , inorganic lithium salts such as inorganic fluoride salts such as LiPF ₆ , LiBF ₄ , LiAsF _{6 , LiCF 3} SO ₃ , Examples thereof include _{perfluoroalcan sulfonates such as LiC 4} F ₉ SO _3, and fluorine-containing organic lithium salts such as perfluoroalcan sulfonic acid imide salts such as Li trifluorosulphonimide ((CF ₃ SO ₂ ) _{2 NLi).} Of these, LiClO ₄ , LiPF ₆ , and LiBF ₄ are preferable.

The lithium salt may be used alone or in combination of two or more. The concentration of the lithium salt in the non-aqueous electrolyte solution is usually in the range of 0.5 mol / L or more and 2.0 mol / L or less.
Further, when the above-mentioned non-aqueous electrolyte solution contains an organic polymer compound and is used in the form of a gel, rubber, or solid sheet, specific examples of the organic polymer compound include polyethylene oxide and polypropylene oxide. Polyether-based polymer compound; Crosslinked polymer of polyether-based polymer compound; Vinyl alcohol-based polymer compound such as polyvinyl alcohol and polyvinyl butyral; Insoluble material of vinyl alcohol-based polymer compound; Polyepicrolhydrin; Polyphosphazene; Poly Siloxane; Vinyl-based polymer compounds such as polyvinylpyrrolidone, polyvinylidene carbonate, polyacrylonitrile; poly (ω-methoxyoligooxyethylene methacrylate), poly (ω-methoxyoligooxyethylene methacrylate-co-methylmethacrylate), poly (hexafluoro) Examples thereof include polymer copolymers such as propylene-vinylidene fluoride).

The non-aqueous electrolyte solution described above may further contain a film-forming agent. Specific examples of the film-forming agent include carbonate compounds such as vinylene carbonate, vinylethyl carbonate and methylphenyl carbonate, alkene sulfides such as ethylene sulfide and propylene sulfide; and sulton compounds such as 1,3-propane sulton and 1,4-butane sulton. Examples thereof include acid anhydrides such as maleic anhydride and succinic anhydride. Further, an overcharge inhibitor such as diphenyl ether or cyclohexylbenzene may be added. When the above additive is used, its content is usually 10% by mass or less, particularly preferably 8% by mass or less, further 5% by mass or less, and particularly preferably 2% by mass or less. If the content of the additive is too large, it may adversely affect other battery characteristics such as an increase in initial irreversible capacity, a decrease in low temperature characteristics, and a decrease in rate characteristics.

Further, as the electrolyte, a polymer solid electrolyte which is a conductor of an alkali metal cation such as lithium ion can also be used. Examples of the polymer solid electrolyte include those in which a salt of lithium is dissolved in the above-mentioned polyether polymer compound, and a polymer in which the terminal hydroxyl group of the polyether is replaced with an alkoxide.
Usually, a porous separator such as a porous membrane or a non-woven fabric is interposed between the positive electrode and the negative electrode in order to prevent a short circuit between the electrodes. In this case, the non-aqueous electrolyte solution is used by impregnating the porous separator. As the material of the separator, polyolefins such as polyethylene and polypropylene, polyether sulfone and the like are used, and polyolefins are preferable.

The form of the non-aqueous secondary battery of the present invention is not particularly limited. Examples include a cylinder type in which the sheet electrode and the separator are spirally formed, a cylinder type having an inside-out structure in which the pellet electrode and the separator are combined, a coin type in which the pellet electrode and the separator are laminated, and the like. Further, by storing the batteries of these forms in an arbitrary outer case, they can be used in any shape such as a coin type, a cylindrical type, and a square type.

The procedure for assembling the non-aqueous secondary battery of the present invention is not particularly limited and may be assembled according to an appropriate procedure according to the structure of the battery. For example, a negative electrode is placed on an outer case and an electrolytic solution is placed on the negative electrode. A separator can be provided, and a positive electrode can be placed so as to face the negative electrode and crimped together with a gasket and a sealing plate to form a battery.

Next, specific embodiments of the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these examples. In the examples, the physical characteristics of the manufactured negative electrode material were measured by the following method.

<Preparation of electrode sheet>
Using the graphite particles of Examples or Comparative Examples, a electrode plate having an active material layer having an active material layer density of 1.35 ± 0.03 g / cm ^{3 was prepared.} Specifically, 50.00 ± 0.02 g of the negative electrode material, 50.00 ± 0.02 g of a 1 mass% carboxymethyl cellulose sodium salt aqueous solution (0.500 g in terms of solid content), and styrene having a weight average molecular weight of 270,000. -0.5 g of an aqueous butadiene rubber dispersion was stirred with a hybrid mixer manufactured by Keyence for 5 minutes and defoamed for 30 seconds to obtain a slurry.

Itochu Machining this slurry so that the negative electrode material adheres to a copper foil having a thickness of 10 μm, which is a current collector, at 6.0 ± 0.3 mg / cm ² or 12.0 ± 0.3 mg / cm ^2. Apply to a width of 10 cm using a small die coater, and roll press using a roller with a diameter of 20 cm ^{to adjust the density of the active material layer to 1.35 ± 0.03 g / cm 3} to obtain an electrode sheet. It was.

<Manufacturing method of non-aqueous secondary battery (laminated battery)>
An electrode sheet having a density of 1.35 ± 0.03 g / cm ³ of the active material layer to which the negative electrode material of 6.0 ± 0.3 mg / cm ^{2 was} attached, which was produced by the above method, was cut into a size of 4 cm × 3 cm and used as a negative electrode.
A positive electrode made of NMC was cut out in the same area, and a separator (made of a porous polyethylene film) was placed between the negative electrode and the positive electrode to combine them. Laminated battery by injecting 200 μl of an electrolytic solution in which _{LiPF 6} is dissolved at 1.2 mol / L in a mixed solvent of ethylene carbonate, ethyl methyl carbonate and dimethyl carbonate (volume ratio = 3: 3: 4). Was produced.

<Low temperature output characteristics>
Using the laminated non-aqueous electrolyte secondary battery produced by the above method for producing a non-aqueous electrolyte secondary battery, the low temperature output characteristics were measured by the following measurement method.
For a non-aqueous electrolyte secondary battery that has not undergone a charge / discharge cycle, the voltage range is 4.1V to 3.0V and the current value is 0.2C at 25 ° C. The current value is 1C, the same applies hereinafter) for 3 cycles, the voltage range is 4.2V to 3.0V, and the current value is 0.2C (when charging, constant voltage charging is performed at 4.2V for another 2.5 hours). Implementation) Initial charging and discharging were performed for 2 cycles.
Further, after charging to 50% SOC at a current value of 0.2C, the current values of 1 / 8C, 1 / 4C, 1 / 2C, 1.5C, and 2C are used for 2 seconds in a low temperature environment of -30 ° C. Discharge with a constant current, measure the drop in battery voltage after 2 seconds in discharging under each condition, and calculate the current value I that can be passed in 2 seconds when the upper limit charging voltage is set to 3V from those measured values. Then, the value calculated by the formula of 3 × I (W) was used as the low temperature output characteristic of each battery.

<Press load>
Using the powder resistance measurement system MCP-PD51 manufactured by Mitsubishi Chemical Analytech Co., Ltd., put 3.0 g of carbon material into a cylindrical container with a diameter of 2 cm so that the density of the carbon material becomes 1.35 g / cc. Press. The load applied at that time was taken as the press load.

<Volume-based average particle size (d50)>
0.01 g of carbon material was suspended in 10 mL of a 0.2 mass% aqueous solution of polyoxyethylene sorbitan monolaurate (for example, Tween 20 (registered trademark)) as a surfactant, and this was used as a measurement sample. Introduced into a commercially available laser diffraction / scattering particle size distribution measuring device (for example, LA-920 manufactured by HORIBA), the measurement sample was irradiated with 28 kHz ultrasonic waves at an output of 60 W for 1 minute, and then the measurement device had a volume-based median diameter. Was measured as.

<True density>
The true density of the carbon material sample was measured by the liquid phase substitution method using an true density measuring instrument (Auto Trudensor MAT-7000 manufactured by Seishin Enterprise Co., Ltd.).

<BET specific surface area (SA)>
Using a surface area meter (specific surface area measuring device "AMS8000" manufactured by Okura Riken Co., Ltd.), 0.4 g of carbon material was filled in the cell, and the carbon material sample was pre-dried at 350 ° C. for 15 minutes under nitrogen flow. It was measured by the nitrogen adsorption BET method by the gas flow method using a nitrogen helium mixed gas accurately adjusted so that the value of the relative pressure of nitrogen with respect to the atmospheric pressure was 0.3.

<TG-DTA measurement>
A differential differential thermal balance TG8120 manufactured by Rigaku Co., Ltd. was used as a measuring device. As the measurement conditions, air was flowed at a flow rate of 100 ml / min, and the temperature rising rate was 10 ° C./min. A platinum pan having a diameter of 5 mm and a height of 2.5 mm was used as the measurement container, and the mass of the measurement sample was 5 mg.

(Example 1)
Scale-like natural graphite having a d50 of 100 μm was pulverized by a dry swirling flow pulverizer ^{to obtain scale-like natural graphite having a d50 of 8.1 μm, a tap density of 0.39 g / cm 3} , and a water content of 0.08% by mass. .. Paraffin-based oil (liquid paraffin, manufactured by Wako Pure Chemical Industries, Ltd., first-class, physical properties at 25 ° C.: viscosity = 95 cP, contact angle = 13.) on 100 g of the obtained scaly natural graphite as a granulating agent.
After adding 12 g of 2 °, surface tension = 31.7 mN / m, rcоs θ = 30.9) and stirring and mixing, the obtained sample is crushed and mixed with a hammer mill (MF10 manufactured by IKA) at a rotation speed of 3000 rpm. Then, a scaly natural graphite having a uniform adhesion of the granulating agent was obtained. The scaly natural graphite uniformly adhered with the obtained granulating agent was adhered to the base material by the hybridization system NHS-1 manufactured by Nara Machinery Co., Ltd., and the fine powder generated during the spheroidizing treatment was attached to the spheroidized particles. Sphericalized graphite particles with a d50 of 13 μm (granulated coal) are subjected to spheroidization treatment by mechanical action for 10 minutes at a rotor peripheral speed of 85 m / sec while being included, and heat-treated at 720 ° C. in an inert gas. Material) was obtained.
The obtained spherical graphite particles are mixed with coal tar pitch as an amorphous carbon precursor, heat-treated at 1300 ° C. in an inert gas, and then the calcined product is crushed and classified to be spherical. A carbonaceous composite carbon material in which graphitic particles and amorphous carbon were composited was obtained. From the firing yield, in the obtained carbonaceous composite carbon material, the mass ratio of the spherical graphite particles to the carbonaceous material (amorphous carbon) having lower crystallinity than the raw material graphite (sphericized natural graphite: amorphous carbon). ) Was confirmed to be 1: 0.07. TG-DTA (1st peak) / (2nd peak) of the obtained sample
, True density, d50, specific surface area, low temperature output characteristics, press load were measured. The results are shown in Table 1.

(Example 2)
The scaly natural graphite having a d50 of 100 μm was pulverized by a mechanical pulverizer having a pulverizing rotor and a liner to obtain a scaly natural graphite having a d50 of 6 μm and a water content of 0.08% by mass. Paraffin-based oil (liquid paraffin, manufactured by Wako Pure Chemical Industries, Ltd., first grade, physical properties at 25 ° C.: viscosity = 95 cP, contact angle = 13.2 °, surface tension = 31) on 100 g of the obtained scaly natural graphite as a granulating agent. After adding 12 g of .7 mN / m, rcоs θ = 30.9) and stirring and mixing, the obtained sample was crushed and mixed with a hammer mill (MF10 manufactured by IKA) at a rotation speed of 3000 rpm to make the granulating agent uniform. A scaly natural graphite adhered to was obtained. The scaly natural graphite uniformly adhered with the obtained granulating agent is adhered to the base material by the hybridization system NHS-1 manufactured by Nara Machinery Co., Ltd., and the fine powder generated during the spheroidizing treatment is attached to the spheroidized particles. Sphericalization treatment was performed by mechanical action for 10 minutes at a rotor peripheral speed of 85 m / sec while encapsulating the particles to obtain spherical graphite particles (granulated carbon material) having a d50 of 9.2 μm. The obtained spherical graphite particles are mixed with coal tar pitch as an amorphous carbon precursor, heat-treated at 1300 ° C. in an inert gas, and then the calcined product is crushed and classified to be spherical. A carbonaceous composite carbon material in which graphitic particles and amorphous carbon were composited was obtained. From the firing yield, in the obtained carbonaceous composite carbon material, the mass ratio of the sphericalized graphite particles to the amorphous carbon (sphericalized graphite particles: amorphous carbon) is 1: 0.10. Was confirmed. Table 1 shows the results of the same measurements as in Example 1.

(Example 3)
The scaly natural graphite having a d50 of 100 μm was pulverized by a mechanical pulverizer having a pulverizing rotor and a liner to obtain a scaly natural graphite having a d50 of 30 μm and a water content of 0.03% by mass. Paraffin-based oil (liquid paraffin, manufactured by Wako Pure Chemical Industries, Ltd., first grade, physical properties at 25 ° C.: viscosity = 95 cP, contact angle = 13.2 °, surface tension = 31) on 100 g of the obtained scaly natural graphite as a granulating agent. After adding 6 g of .7 mN / m, rcоs θ = 30.9) and stirring and mixing, the obtained sample was crushed and mixed with a hammer mill (MF10 manufactured by IKA) at a rotation speed of 3000 rpm, and the granulating agent was uniform. A scaly natural graphite adhered to was obtained. The scaly natural graphite uniformly adhered with the obtained granulating agent is adhered to the base material by the hybridization system NHS-1 manufactured by Nara Machinery Co., Ltd., and the fine powder generated during the spheroidizing treatment is attached to the spheroidized particles. While encapsulating, sphericalization treatment was performed by mechanical action at a rotor peripheral speed of 85 m / sec for 10 minutes to obtain spherical graphite particles (granulated carbon material) having a d50 of 19.4 μm. The obtained spherical graphite particles are mixed with coal tar pitch as an amorphous carbon precursor, heat-treated at 1300 ° C. in an inert gas, and then the fired product is crushed and classified to be spherical. A carbonaceous composite carbon material in which natural graphite and amorphous carbon were composited was obtained. From the calcined yield, the mass ratio of the sphericalized graphite particles to the amorphous carbon (sphericalized graphite particles: amorphous carbon) is 1: 0.042 in the obtained carbonaceous composite carbon material. Was confirmed. Table 1 shows the results of the same measurements as in Example 1.

(Example 4)
The spherical graphite particles obtained in Example 3 are mixed with coal tar pitch as an amorphous carbon precursor, heat-treated at 1300 ° C. in an inert gas, and then the fired product is crushed and classified. To obtain a carbonaceous composite carbon material in which spherical graphitic particles and amorphous carbon were composited. From the firing yield, in the obtained carbonaceous composite carbon material, the mass ratio of the sphericalized graphite particles to the amorphous carbon (sphericalized graphite particles: amorphous carbon) is 1: 0.05. Was confirmed. Table 1 shows the results of the same measurements as in Example 1.

( Reference example 5)
The spherical graphite particles obtained in Example 3 are mixed with coal tar pitch as an amorphous carbon precursor, heat-treated at 1300 ° C. in an inert gas, and then the fired product is crushed and classified. To obtain a carbonaceous composite carbon material in which spherical graphitic particles and amorphous carbon were composited. From the firing yield, in the obtained carbonaceous composite carbon material, the mass ratio of the sphericalized graphite particles to the amorphous carbon (sphericalized graphite particles: amorphous carbon) is 1: 0.10. Was confirmed. Table 1 shows the results of the same measurements as in Example 1.

(Comparative Example 1)
Scale-like natural graphite having a d50 of 100 μm was spheroidized by mechanical action for 3 minutes at a rotor peripheral speed of 85 m / sec using a hybridization system NHS-1 manufactured by Nara Machinery Co., Ltd. It was confirmed that the obtained sample contained a large amount of scaly graphite in a state where it was not attached to or contained in the base material and scaly graphite-like fine powder generated during the spheroidizing treatment. The scaly graphite-like fine particles were removed from this sample by classification to obtain spherical graphite particles having a d50 of 15.7 μm. The obtained spherical graphite particles are mixed with coal tar pitch as an amorphous carbon precursor, heat-treated at 1300 ° C. in an inert gas, and then the calcined product is crushed and classified to be spherical. A carbonaceous composite carbon material in which graphitic particles and amorphous carbon were composited was obtained. From the firing yield, in the obtained carbonaceous composite carbon material, the mass ratio of the sphericalized graphite particles to the amorphous carbon (sphericalized graphite particles: amorphous carbon) is 1: 0.04. Was confirmed. Table 1 shows the results of the same measurements as in Example 1.

(Comparative Example 2)
Scale-like natural graphite having a d50 of 100 μm was spheroidized by mechanical action for 10 minutes at a rotor peripheral speed of 85 m / sec using a hybridization system NHS-1 manufactured by Nara Machinery Co., Ltd. It was confirmed that the obtained sample contained a large amount of scaly graphite in a state where it was not attached to or contained in the base material and scaly graphite-like fine powder generated during the spheroidizing treatment. The scaly graphite-like fine particles were removed from this sample by classification to obtain spherical graphite particles having a d50 of 10.8 μm. The obtained spherical graphite particles are mixed with coal tar pitch as an amorphous carbon precursor, heat-treated at 1000 ° C. in an inert gas, and then the calcined product is crushed and classified to obtain graphite particles. A carbonaceous composite carbon material in which and amorphous carbon were compounded was obtained. From the firing yield, in the obtained carbonaceous composite carbon material, the mass ratio of the sphericalized graphite particles to the amorphous carbon (sphericalized graphite particles: amorphous carbon) is 1: 0.06. Was confirmed. Table 1 shows the results of the same measurements as in Example 1.

(Comparative Example 3)
Scale-like natural graphite having a d50 of 100 μm was spheroidized by mechanical action for 3 minutes at a rotor peripheral speed of 85 m / sec using a hybridization system NHS-1 manufactured by Nara Machinery Co., Ltd. It was confirmed that the obtained sample contained a large amount of scaly graphite in a state where it was not attached to or contained in the base material and scaly graphite-like fine powder generated during the spheroidizing treatment. The scaly graphite-like fine particles were removed from this sample by classification to obtain spherical graphite particles having a d50 of 15.7 μm. The obtained spherical graphite particles are mixed with coal tar pitch as an amorphous carbon precursor, heat-treated at 3000 ° C. in an inert gas, and then the calcined product is crushed and classified to be spherical. A carbonaceous composite carbon material in which graphitic particles and amorphous carbon were composited was obtained. From the firing yield, in the obtained carbonaceous composite carbon material, the mass ratio of the sphericalized graphite particles to the amorphous carbon (sphericalized graphite particles: amorphous carbon) is 1: 0.15. Was confirmed. Table 1 shows the results of the same measurements as in Example 1.

(Comparative Example 4)
Scale-like natural graphite having a d50 of 100 μm was spheroidized by mechanical action for 10 minutes at a rotor peripheral speed of 85 m / sec using a hybridization system NHS-1 manufactured by Nara Machinery Co., Ltd. It was confirmed that the obtained sample contained a large amount of scaly graphite in a state where it was not attached to or contained in the base material and scaly graphite-like fine powder generated during the spheroidizing treatment. The scaly graphite-like fine particles were removed from this sample by classification to obtain spherical graphite particles having a d50 of 7.8 μm. 2 parts by mass of the obtained spherical graphite particles and carbon black having a primary particle diameter of 24 nm, a BET specific surface area of 115 m2 / g, and a DBP oil absorption of 110 ml / 100 g were added to 100 parts by mass of the spherical graphite particles. Then, a rotary mixer having a mechanism for crushing carbon black aggregates by a chopper and a mechanism for mixing and stirring powder by rotating a shovel is used to stir for 20 minutes at a chopper rotation speed of 3000 rpm to combine spherical graphitic particles and carbon black. I got a body. The obtained composite and coal tar pitch as an amorphous carbon precursor are mixed, heat-treated at 1100 ° C. in an inert gas, and then the calcined product is crushed and classified to form spherical graphitic particles. A carbonaceous composite carbon material in which a composite of carbon black and amorphous carbon was compounded was obtained. From the firing yield, in the obtained carbonaceous composite carbon material, the mass ratio of the composite of spherical graphite particles and carbon black to amorphous carbon (composite of spherical natural graphite and carbon black: amorphous). Carbon) was confirmed to be 1: 0.03. Table 1 shows the results of the same measurements as in Example 1.

(Comparative Example 5)
Graphite particles are obtained by mixing scaly natural graphite having a d50 of 5 μm and coal tar pitch as an amorphous carbon precursor, heat-treating at 1300 ° C. in an inert gas, and then crushing and classifying the calcined product. A carbonaceous composite carbon material in which and amorphous carbon were compounded was obtained. From the firing yield, it was confirmed that the mass ratio of graphitic particles to amorphous carbon (graphite particles: amorphous carbon) was 1: 0.06 in the obtained carbonaceous composite carbon material. .. Table 1 shows the results of the same measurements as in Example 1.

In Examples 1 to 5, the ratio of the first peak to the second peak of TG-DTA was adjusted by adding a granulating agent having the specified physical characteristics to the scaly natural graphite adjusted to the specified particle size and performing the granulation treatment. Since it was within the specified range, the press load was small and high low temperature output characteristics were exhibited. On the other hand, it was confirmed that in Comparative Examples 1 to 5 outside the specified range, the low temperature input / output characteristics were lowered and the press load was increased.

By using the carbon material of the present invention as an active material for the negative electrode of a non-aqueous secondary battery, it is possible to provide a non-aqueous secondary battery having excellent input / output characteristics and press characteristics. Further, according to the method for producing the material, since the number of steps is small, stable, efficient and inexpensive production can be performed.

Claims (6)

A carbon material for non-aqueous secondary batteries that contains a carbonaceous material on the surface of the granulated carbon material.
The granulated carbon material is graphite,
The carbonaceous material is amorphous carbon,
The volume-based average particle size (d50) is 19.4 μm or less, and
DTA (Differential Thermal Analysis) obtained when TG-DTA measurement is performed
The curve has a first peak on the relatively low temperature side and a second peak on the relatively high temperature side in the range of 500 ° C. or higher and 1000 ° C. or lower, and the first peak and the second peak. Is a carbon material for a non-aqueous secondary battery, which satisfies the following formula 1.
(Equation 1)
(DTA [μV] at the first peak) / (DTA [μV] at the second peak) ≧
0.4 The carbon material for a non-aqueous secondary battery according to claim 1, wherein the BET specific surface area measured by nitrogen adsorption is 2.0 m ^{2 / g or more.} True density of 1.90 g / cm ³ or more, a non-aqueous secondary battery carbon material according to claim 1 or 2, characterized in that less than 2.26 g / cm ^3. The carbon material for a non-aqueous secondary battery according to any one of claims 1 to 3, wherein the average circularity obtained from the flow-type particle image analysis is 0.91 or more. The charcoal for a non-aqueous secondary battery according to any one of claims 1 to 4, wherein the granulated carbon material is spheroidal graphite particles obtained by granulating scaly graphite, scaly graphite, and massive graphite. Material. A positive electrode and a negative electrode capable of storing and releasing lithium ions, and an electrolyte are provided, and the negative electrode includes a current collector and a negative electrode active material layer formed on the current collector, and the negative electrode active material layer is provided. A non-aqueous secondary battery comprising the carbon material according to any one of claims 1 to 5.

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