JP2018163868A - Negative electrode material for non-aqueous secondary battery, negative electrode for non-aqueous secondary battery, and non-aqueous secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a negative electrode material for a non-aqueous secondary battery, which has a high capacity and has both low-temperature output characteristics and high-temperature storage characteristics at a high level, and a negative electrode for a non-aqueous secondary battery and a non-aqueous secondary battery containing the same. .. A surface area (SAa) corresponding to pores of 1 nm to 4 nm and a fine particle size of 4 nm to 150 nm are included in a pore size distribution obtained by a nitrogen adsorption method, containing graphite having amorphous carbon on at least a part of the surface. The negative electrode material for a non-aqueous secondary battery satisfies the following conditions (1) and (2) with respect to the surface area (SAb) corresponding to the holes. Condition (1): SAa is 1.80 m2/g or less. Condition (2): SAb/SAa is 1.30 or more. [Selection diagram] None

Description

  The present invention relates to a negative electrode material for a non-aqueous secondary battery excellent in low-temperature output characteristics and storage characteristics. The present invention also relates to a non-aqueous secondary battery negative electrode and a non-aqueous secondary battery including the non-aqueous secondary battery negative electrode material.

In recent years, demand for high-capacity secondary batteries has increased with the downsizing of electronic devices. In particular, non-aqueous secondary batteries having higher energy density and excellent rapid charge / discharge characteristics, particularly lithium ion secondary batteries, are attracting attention as compared to nickel / cadmium batteries and nickel / hydrogen batteries. In particular, positive and negative electrodes capable of inserting and extracting lithium ions, and nonaqueous lithium secondary batteries made of a nonaqueous electrolyte solution in which lithium salts such as LiPF ₆ and LiBF ₄ are dissolved have been developed and put into practical use.

  Various negative electrode materials have been proposed for this non-aqueous lithium secondary battery, but graphite such as natural graphite and coke is used because of its high capacity and excellent discharge potential flatness. Graphite carbon materials such as artificial graphite, graphitized mesophase pitch, and graphitized carbon fiber obtained by crystallization are used. An amorphous carbon material is also used because it is relatively stable with respect to some electrolyte solutions. Furthermore, the amorphous carbon is coated or adhered to the surface of the graphite particles, and there are two characteristics: a high capacity and low irreversible capacity due to graphite, and excellent stability with an electrolyte solution due to amorphous carbon. Carbon materials with combined characteristics are also used.

  As described above, various graphite-based carbon materials have been conventionally used as the negative electrode material. However, Patent Document 1 discloses an integrated pore volume of the carbon material as a further improvement of the processing process of the graphite itself. It is disclosed that a specific range and a ratio of the pore size to the volume-based average particle size (PD / d50 (%)) within a specific range is excellent in low-temperature output characteristics.

International Publication No. 16/006617

  According to studies by the present inventors, the negative electrode material for non-aqueous secondary batteries described in Patent Document 1 has a high surface area derived from micropores with a specific diameter that adversely affect low-temperature output characteristics and high-temperature storage. The present inventors have found that there is a problem that the low temperature output characteristics and the high temperature storage characteristics are insufficient. That is, an object of the present invention is a negative electrode material for a non-aqueous secondary battery that has a high capacity and has both low temperature output characteristics and high temperature storage characteristics at a high level, and a negative electrode for a non-aqueous secondary battery and a non-aqueous secondary battery including the same. The next battery is to provide.

  As a result of intensive studies to solve the above problems, the present inventors can solve the above problems by using a negative electrode material for non-aqueous secondary batteries containing graphite and having a specific value for the fine pore distribution determined from the nitrogen adsorption method. I found out. That is, the gist of the present invention is as follows.

[1] At least a portion of the surface contains graphite having amorphous carbon, and in the pore distribution determined by the nitrogen adsorption method, the surface area (SA _a ) corresponding to the pores of 1 nm to 4 nm and the fineness of 4 nm to 150 nm A negative electrode material for a non-aqueous secondary battery that satisfies the following conditions (1) and (2) for the surface area (SA _b ) corresponding to the pores.
Condition (1): SA _a is 1.80 m ² / g or less.
Condition (2): SA _b / SA _a is 1.30 or more.

[2] The negative electrode material for nonaqueous secondary batteries according to [1], wherein the pore distribution satisfies the following condition (3).
Condition (3): SA _a is 1.50 m ² / g or more.

[3] The negative electrode material for a nonaqueous secondary battery according to [1] or [2], wherein the Raman R value represented by the following formula is 0.20 or more.
[Raman R value] = [Intensity I _B of peak P _B near 1360 cm ⁻¹ in Raman spectral analysis] / [Intensity I _A of peak P _A near 1580 cm ⁻¹ ]

[4] The non-aqueous secondary battery according to any one of [1] to [3], wherein the surface functional group amount O / C value obtained by X-ray photoelectron spectroscopy (XPS) is 3 mol% or less. Carbon material.

[5] The non-aqueous secondary battery according to any one of [1] to [4], wherein a thermal weight reduction rate between 200 ° C. and 600 ° C. obtained from a differential thermobalance is 1% or less. Carbon material.

[6] The negative electrode material for a non-aqueous secondary battery according to any one of [1] to [5], wherein the circularity determined by flow particle image analysis is 0.88 or more.

[7] The negative electrode material for a non-aqueous secondary battery according to any one of [1] to [6], including spheroidized graphite as the graphite.

[8] A mass ratio of the amorphous carbon to the graphite ([[amorphous carbon mass] / [graphite mass]] × 100) is 0.1% or more and 30% or less. [1] Thru | or the negative electrode material for non-aqueous secondary batteries as described in any one of [7].

[9] A current collector and an active material layer formed on the current collector, wherein the active material layer contains the negative electrode material according to any one of [1] to [8]. Negative electrode for non-aqueous secondary battery.

[10] A nonaqueous secondary battery comprising a positive electrode and a negative electrode, and an electrolyte, wherein the negative electrode is the negative electrode for a nonaqueous secondary battery according to [9].

  ADVANTAGE OF THE INVENTION According to this invention, the negative electrode material for non-aqueous secondary batteries which is high capacity | capacitance and can make low-temperature input / output characteristics and high-temperature storage characteristics compatible at a higher level, and the negative electrode for non-aqueous secondary batteries and non-aqueous secondary batteries including the same A battery is provided.

It is a graph which shows the result of an Example and a comparative example.

  Hereinafter, the present invention will be described in detail, but the present invention is not limited to the following description, and can be arbitrarily modified and implemented without departing from the gist of the present invention. In addition, in this invention, when expressing by putting a numerical value or a physical-property value before and behind using "-", it shall use as what includes the value before and behind.

[Non-aqueous secondary battery anode material]
The negative electrode material for a non-aqueous secondary battery of the present invention (hereinafter sometimes simply referred to as “the negative electrode material of the present invention”) contains graphite having amorphous carbon on at least a part of its surface, and is a nitrogen adsorption method. In the pore distribution obtained from the above, the following conditions (1) and (2) are satisfied for the surface area (SA _a ) corresponding to pores of 1 nm to 4 nm and the surface area (SA _b ) corresponding to pores of 4 nm to 150 nm: It is. In addition, the negative electrode material of the present invention preferably satisfies the following condition (3) with respect to the pore distribution.
Condition (1): SA _a is 1.80 m ² / g or less.
Condition (2): SA _b / SA _a is 1.30 or more.
Condition (3): SA _a is 1.50 m ² / g or more.

The negative electrode material for a non-aqueous secondary battery according to the present invention has a high capacity and exhibits an effect that both low temperature input / output characteristics and high temperature storage characteristics can be achieved at a higher level. The reason why the negative electrode material of the present invention has such an effect is not clear, but in the negative electrode material described in Patent Document 1, pores of 1 nm to 4 nm are filled with a binder during electrode formation, and these fine particles are The insertion / extraction of Li ions on the surface of the negative electrode material in the pores is hindered, resulting in poor low-temperature input / output characteristics. Furthermore, during storage at high temperatures, the electrolyte swells in the binder and contacts the surfaces inside these pores. It is considered that the storage characteristics were deteriorated due to decomposition. On the other hand, the negative electrode material of the present invention has more Li ion insertion / desorption sites than graphite with a developed crystal structure, and amorphous carbon having excellent Li ion insertion / desorption reactivity on the graphite surface. It is estimated that the low-temperature input / output characteristics are improved by having at least a part. In particular, when the surface area (SA _a ) corresponding to the pores of 1 nm to 4 nm is reduced, the decomposition side reaction does not occur in order to prevent the electrolyte from entering the pores even during high temperature storage, and low temperature input / output characteristics and high temperature Preservation characteristics are estimated to improve. On the other hand, pores of 4 nm to 150 nm are hard to be filled with a binder, and insertion and desorption of Li ions are difficult to be inhibited on the surface inside these pores, so that they proceed smoothly. It is estimated that the low temperature input / output characteristics are improved by increasing the surface area (SA _b ) corresponding to pores of 4 nm to 150 nm. As a result, it is estimated that both low-temperature input / output characteristics and storage characteristics can be achieved.

[graphite]
The negative electrode material of the present invention contains graphite having amorphous carbon on at least a part of its surface. When used in a lithium ion secondary battery, this graphite is not particularly limited as long as it has amorphous carbon on at least a part of its surface, but it must be capable of occluding and releasing lithium ions. Is preferred. Specific examples of graphite include artificial graphite produced by heating scaly, massive, or plate-like natural graphite, petroleum coke, coal pitch coke, coal needle coke, and mesophase pitch to 2500 ° C. or higher. it can.

  In addition, it is preferable to apply mechanical energy treatment to these graphites from the viewpoint that the graphite is spheroidized, and the low-temperature input / output characteristics are increased by increasing the amount of edges that act as Li ion insertion / desorption sites in the graphite. Is preferable. The mechanical energy treatment uses, for example, a device having a rotor with a large number of blades installed inside the casing, and rotates the rotor at a high speed, so that the natural graphite or artificial graphite introduced therein is subjected to impact compression and friction. And it can manufacture by giving mechanical actions, such as shear force, repeatedly.

In the negative electrode material of the present invention, it is preferable that spheroidized graphite is included as graphite because the packing property is increased and the active material layer can be densified, so that the capacity can be increased. Therefore, it is preferable because the electrolyte solution moves smoothly and the rapid charge / discharge characteristics are improved. Such spheroidized graphite can be obtained by spheroidizing various types of graphite. Examples of the spheroidizing method include, for example, a method in which a shearing force or a compressive force is applied to mechanically approximate a spherical shape, and a mechanical / physical processing in which a plurality of fine particles are granulated by the adhesive force of the binder or the particles themselves. Methods and the like.

  Furthermore, the negative electrode material of the present invention is made of graphite, and a resin such as petroleum-based or coal-based tar or pitch, polyvinyl alcohol, polyacrylonitrile, phenol resin, cellulose or the like is added to the above spheroidized graphite. At least a portion of the surface by firing at 500 ° C. to 2000 ° C., preferably 600 ° C. to 1800 ° C., more preferably 700 to 1600 ° C., more preferably 800 to 1500 ° C. in a non-oxidizing atmosphere. Thus, graphite having amorphous carbon can be obtained. The negative electrode material of the present invention further improves the low-temperature input / output characteristics by using graphite having amorphous carbon on at least a part of the surface.

In particular, in the negative electrode material of the present invention, the mass ratio of graphite and amorphous carbon ([[mass of amorphous carbon] / [mass of graphite]] × 100) is preferably 0.1% or more, More preferably, it is 1% or more, more preferably 3% or more, particularly preferably 5% or more, and most preferably 6% or more. On the other hand, it is preferably 30% or less, more preferably 20% or less, and still more preferably 15% or less. When the mass ratio is within the above range, a high capacity, and, since there is a tendency that it is possible to reduce the SA _a affecting the low temperature output characteristics and high-temperature storage, excellent low-temperature output characteristics and high-temperature storage characteristics This is preferable. In addition, said mass ratio can be calculated | required from a baking yield.

[Physical properties]
The negative electrode material of the present invention has the following specific pore distribution. Moreover, it is preferable that the negative electrode material of the present invention satisfies the following physical properties.

<Pore distribution (nitrogen adsorption method)>
In the negative electrode material of the present invention, the fine pore distribution obtained from the nitrogen adsorption method has the following specific value.

First, in the negative electrode material of the present invention, the surface area (SA _a ) corresponding to pores of 1 nm to 4 nm has an adverse effect during low temperature output characteristics and high temperature storage if the value is too large, so that it is 1.80 m ² / g or less. It is. From this viewpoint, SA _a is preferably 1.60 m ² / g or less, more preferably 1.40 m ² / g or less, still more preferably 1.30 m ² / g or less, and particularly preferably 1.20 m ² / g. It is as follows. On the other hand, it is not limited in particular lower limit of the SA _a, usually at 0.10 m ² / g or more, preferably 0.30 m ² / g or more.

In the negative electrode material of the present invention, the surface area (SA _b ) corresponding to pores of 4 nm to 150 nm is preferably 1.50 m ² / g or more for improving low-temperature input / output characteristics. SA _b From this viewpoint, preferably at 2.00 m ² / g or more, more preferably 2.40 m ² / g or more, more preferably 3.00 m ² / g or more, particularly preferably 3.50 m ² / g As mentioned above, Most preferably, it is 4.00 m < ² > / g or more. On the other hand, the upper limit of SA _b is not particularly limited, but is usually 10 m ² / g or less, preferably 8 m ² / g or less, more preferably 7 m ² / g or less.

The ratio of SA _b to SA _a (SA _b / SA _a ) is 1.30 or more because low temperature output characteristics and high temperature storage characteristics can be achieved at a higher level. From this viewpoint, SA _b / SA _a is preferably 1.80 or more, more preferably 2.20 or more, still more preferably 2.50 or more, and particularly preferably 3.00 or more. On the other hand, the upper limit of (SA _b / SA _a ) is not particularly limited, but is usually 10 or less, preferably 8 or less, more preferably 6 or less.

Such a pore distribution can be obtained by a nitrogen adsorption method. Specifically, after performing heat treatment under reduced pressure at 100 ° C. for 3 hours, an adsorption isotherm (at a liquid nitrogen temperature in an autosorb 3B manufactured by Cantachrome) Adsorption gas: nitrogen) is measured, and the mesopore volume and mesopore surface area at each pore diameter can be determined by BJH analysis using the obtained adsorption isotherm. The mesopore surface area by BJH method area analysis can be calculated by assuming that the mesopore is cylindrical and integrating the side areas.

<Raman R value>
Raman R value in the present invention, the intensity _{I A} of the peak _{P A} in the vicinity of 1580 cm ^-1 in the Raman spectrum obtained by Raman spectroscopy for the negative electrode material of the present invention, the intensity _{I B} of a peak _{P B} in the vicinity of 1360 cm ^-1 Is defined as the intensity ratio (I _B / I _A ) when measured. Incidentally, the scope of 1580～1620Cm ^-1 A "1580cm around ^-1", the "1360cm around ^-1" refers to the range of 1350 ^-1.

  The Raman R value of the negative electrode material of the present invention is preferably 0.20 or more, more preferably 0.25 or more, still more preferably 0.30 or more, and particularly preferably 0.35 or more. Moreover, it is 1.00 or less normally, Preferably it is 0.70 or less, More preferably, it is 0.60 or less, More preferably, it is 0.50 or less. If the Raman R value is too small, it indicates that the crystallinity of the negative electrode material surface is too high, and the low-temperature input / output characteristics may deteriorate due to the difficulty in inserting and desorbing Li ions. On the other hand, if the Raman R value is too large, the influence of the irreversible capacity of amorphous carbon increases and the side reaction with the electrolyte increases, resulting in a decrease in the initial charge / discharge efficiency of the lithium ion secondary battery and an increase in the amount of gas generated. Battery capacity tends to decrease.

The Raman spectrum is measured by a Raman spectrometer. Specifically, the sample particles are naturally dropped into the measurement cell to fill the sample, and the measurement cell is rotated in a plane perpendicular to the laser beam while irradiating the measurement cell with an argon ion laser beam. Measure.
Argon ion laser light wavelength: 514.5 nm
Laser power on sample: 25 mW
Resolution: 4cm ^-1
Measurement range: 1100 cm ^{−1 to} 1730 cm ⁻¹
Peak intensity measurement, peak half-width measurement: Background processing, smoothing processing (5 points of convolution by simple averaging)

<Surface functional group amount O / C value (mol%)>
The surface functional group amount O / C value (mol%) in the present invention can be measured using an X-ray photoelectron spectrometer (for example, ESCA manufactured by ULVAC-PHI) as X-ray photoelectron spectroscopy measurement (XPS). . Specifically, an object to be measured (here, the negative electrode material) is placed on a sample stage so that the surface is flat, and Kα ray of aluminum is used as an X-ray source, and C1s (280 to 300 eV) and O1s ( 525-545 eV) is measured. The obtained C1s peak top is corrected to be 284.3 eV, the peak areas of the C1s and O1s spectra are obtained, and the device sensitivity coefficient is multiplied to calculate the surface atomic concentrations of C and O, respectively. The obtained O / C atomic concentration ratio O / C (O atom concentration / C atom concentration) × 100 is defined as the surface functional group amount O / C value of the negative electrode material.

  The O / C value obtained from XPS is preferably 0.01 mol% or more, more preferably 0.1 mol% or more, still more preferably 0.2 mol% or more, particularly preferably 0.3 mol% or more, preferably 3 mol% or less. More preferably, it is 2.5 mol% or less, More preferably, it is 2 mol% or less, Most preferably, it is 1.5 mol% or less. If the surface functional group amount O / C value is within the above range, the desolvation reactivity of the Li ion and the electrolyte solvent on the negative electrode surface is promoted, the rapid charge / discharge characteristics are improved, and the side reaction with the electrolyte is prevented. The charge / discharge efficiency tends to be suppressed.

<Thermal weight reduction rate (%)>
The thermal weight reduction rate of the negative electrode material of the present invention is preferably 1% or less, preferably 0.5% or less, more preferably 0.3% or less, still more preferably 0.2% or less, particularly preferably 0.1. % Or less. If the thermal weight loss rate exceeds the above range, it indicates that the high-temperature stability of the coating material filling the micropores is low, and the high-temperature storage characteristics tend to deteriorate because the electrolyte swells into the graphite micropores during high-temperature storage. There is.

  In addition, the thermogravimetric reduction rate in this invention can be calculated | required using a differential thermal balance (the Rigaku company make, TG8120). Specifically, 5 mg of the negative electrode material powder was weighed into a platinum pan and introduced into a differential thermobalance, and the temperature was raised from room temperature to 600 ° C. at a temperature rising rate of 10 ° C./min in a nitrogen stream at 200 mL / min. Measure the decrease. And the value which computed the thermogravimetric reduction rate between 200 degreeC and 600 degreeC in the said measurement is defined as the thermogravimetric reduction rate (%) in this invention.

<Circularity>
The negative electrode material of the present invention preferably has a circularity determined by flow-type particle image analysis of 0.88 or more, more preferably 0.90 or more, and further preferably 0.92 or more. . A negative electrode material having such a high degree of circularity is preferable because the degree of bending of Li ion diffusion is lowered, the electrolyte solution moves smoothly between the interparticle voids, and the rapid charge / discharge characteristics can be improved. On the other hand, the circularity is usually less than 1, preferably 0.98 or less, more preferably 0.96 or less. If the degree of circularity is too high, it becomes a true sphere, so that the contact area between the negative electrode materials decreases and the cycle characteristics may deteriorate.

In addition, circularity is calculated | required by calculating the average circularity by measuring the particle size distribution by a circle equivalent diameter using a flow type particle image analyzer (FPIA-2000 by Toa Medical Electronics Co., Ltd.). The circularity is defined by the following formula. When the circularity is 1, a theoretical sphere is obtained.
[Circularity] = [Perimeter of equivalent circle having the same area as the projected particle shape] / [Actual perimeter of projected particle shape]

  In this circularity measurement, ion-exchanged water is used as a dispersion medium, and polyoxyethylene (20) monolaurate is used as a surfactant. The equivalent circle diameter is the diameter of a circle (equivalent circle) having the same projected area as the photographed particle image, and the circularity is the circumference of the equivalent particle as a molecule and the circumference of the photographed particle projection image. The ratio is the denominator. The circularity of particles having a measured equivalent diameter in the range of 10 to 40 μm is averaged to obtain the circularity.

<Volume standard average particle diameter (average particle diameter d50)>
The negative electrode material of the present invention has a volume-based average particle diameter (also referred to as “average particle diameter d50”) of preferably 1 μm or more, more preferably 3 μm or more, still more preferably 4 μm or more, and particularly preferably 5 μm or more. Further, it is preferably 50 μm or less, more preferably 40 μm or less, still more preferably 30 μm or less, particularly preferably 25 μm or less, and most preferably 20 μm or less. If the average particle size d50 is too small, the irreversible capacity tends to increase and the initial battery capacity is lost. On the other hand, if the average particle size d50 is too large, process inconveniences such as striping in slurry coating occur, rapid charge / discharge. It may cause deterioration of characteristics and low temperature input / output characteristics.

The average particle diameter d50 is obtained by suspending 0.01 g of composite particles in 10 mL of a 0.2% by mass aqueous solution of polyoxyethylene sorbitan monolaurate (for example, Tween 20 (registered trademark)) as a surfactant. This was introduced into a commercially available laser diffraction / scattering particle size distribution measuring apparatus (for example, LA-920 manufactured by HORIBA) as a measurement sample, and the measurement apparatus was irradiated with 28 kHz ultrasonic waves at an output of 60 W for 1 minute. It is defined to be measured as a volume-based median diameter.

<Tap density>
The tap density of the negative electrode material of the present invention is preferably 0.8 g / cm ³ or more, more preferably 0.85 g / cm ³ or more, still more preferably 0.88 g / cm ³ or more, particularly preferably 0.8. 9 g / cm ³ or more, most preferably 0.93 g / cm ³ or more, preferably 1.3 g / cm ³ or less, more preferably 1.2 g / cm ³ or less, and even more preferably 1.1 g / cm 3 ³ or less. When the tap density of the negative electrode material is equal to or more than the above lower limit, the processability such as streaking during the production of the electrode plate is improved, and the filling property of the negative electrode material layer is improved, so that the rollability is good and the high density negative electrode sheet. Is preferable from the viewpoint that the electrolyte solution moves smoothly and the rapid charge / discharge characteristics are improved because the shape of the interparticle voids when the electrode body is formed is easy. It is preferable from the viewpoint of being excellent in low-temperature input / output characteristics and rapid charge / discharge characteristics because it has an appropriate space on the surface and inside of the particles if the upper limit value or less.

  This tap density is measured using a powder density measuring instrument tap denser KYT-3000 (manufactured by Seishin Enterprise Co., Ltd.). Specifically, after dropping the sample into a 20 cc tap cell and filling the cell fully, tap with a stroke length of 10 mm is performed 1000 times, and the density at that time is defined as the tap density.

<Specific surface area (BET-SA)>
The negative electrode material of the present invention has a specific surface area (BET-SA) by the BET method of usually 1 m ² / g or more, preferably 1.5 m ² / g or more, more preferably 2 m ² / g or more, still more preferably 2. and a 5 m ² / g or more, whereas generally ^{30 m} 2 / g or less, preferably ^{20 m} 2 / g or less, more preferably ^17m 2 / g or less, still more preferably not more than ^{15 m} 2 / g. When the BET-SA is above this range, the portion where Li ions enter and exit is secured, and the rapid charge / discharge characteristics and low temperature input / output characteristics of the lithium ion secondary battery tend to be good, When the specific surface area exceeds this range, the activity of the active material with respect to the electrolytic solution is not excessive when the specific surface area is below the above upper limit value, and side reactions with the electrolytic solution are suppressed, and the initial charge / discharge efficiency of the battery is reduced and the amount of gas generated The battery capacity tends to be improved.

  In addition, in the negative electrode material of the present invention, BET-SA can be measured using a Maxorb manufactured by Mountec. Specifically, the sample was subjected to preliminary vacuum drying at 100 ° C. for 3 hours under nitrogen flow, and then cooled to the liquid nitrogen temperature so that the relative pressure value of nitrogen with respect to atmospheric pressure was 0.3. It can be measured by a nitrogen adsorption BET one-point method using a gas flow method using a precisely adjusted nitrogen helium mixed gas.

[Production method]
The method for producing the negative electrode material for a non-aqueous secondary battery of the present invention is not particularly limited as long as it can be produced so as to satisfy the above conditions (1) and (2). The scale-like natural graphite whose particle size was adjusted so that the particle size was adjusted to 80 μm or less and the fine pore amount of 1 nm to 150 nm was adjusted, and fine pores of 1 nm to 4 nm were formed in the presence of a granulated material containing an organic compound that became amorphous carbon. While filling, the fine powder produced during the spheronization (granulation) treatment adheres to the base material that becomes the spheroidized graphite (hereinafter sometimes referred to as spheroidized graphite) and / or Spheroidizing while encapsulating in particles to reduce 1 to 4 nm micropores while increasing 4 to 150 nm micropores, and then coat with an organic compound as a raw material for amorphous carbon 1nm depending on Reducing 4nm micropores _include a method of adjusting the SA b / SA _a within a predetermined range.

Specifically, it has a granulation step of granulating the raw material carbon material by imparting at least one of mechanical energy of impact, compression, friction, and shear force to graphite, and the granulation step, It is preferable to carry out in the presence of a granulating agent that satisfies the following conditions 1), 2) and 3).
1) The granulating material is liquid during the step of granulating the raw carbon material.
2) The granulated material contains an organic compound that becomes amorphous carbon.
3) When an organic solvent is not included as a granulating agent or an organic solvent is included, 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. Use things.

If it has the said granulation process, you may further have another process as needed. Another process may be implemented independently and multiple processes may be implemented simultaneously. As one embodiment, one including the following first to fifth steps may be mentioned. Hereinafter, these steps will be described.
(1st process) The process of adjusting the particle size of raw material carbon material (2nd process) The process of mixing raw material carbon material and a granulating agent (3rd process) The process of granulating raw material carbon material (4th process) Step of removing granules (fifth step) Step of attaching an amorphous carbonaceous material having lower crystallinity than the raw carbon material to the granulated carbon material

(1st process) The process which adjusts the particle size of raw material carbon material The graphite mentioned above is used for the raw material carbon material used for manufacture of the negative electrode material for non-aqueous secondary batteries of this invention.

  The raw carbon material is preferably adjusted to the following particle size in the first step. That is, the average particle diameter (d50) of the obtained raw material carbon material is preferably 1 μm or more, more preferably 2 μm or more, still more preferably 3 μm or more, while preferably 80 μm or less, more preferably 50 μm or less, and even more preferably. Is 35 μm or less, particularly preferably 20 μm or less, particularly preferably 10 μm or less, and most preferably 8 μm or less.

  When d50 is in the above range, the amount of edges that can be used as Li ion insertion / desorption sites in the spheroidized graphite increases, so the low-temperature output characteristics and cycle characteristics tend to be improved. Furthermore, since the circularity of the spheroidized graphite can be adjusted to be high, the bending degree of Li ion diffusion can be lowered, so that the electrolyte solution moves smoothly in the interparticle voids, and the rapid charge / discharge characteristics are improved. Further, when d50 is in the above range, the fine powder generated during the granulation step adheres to the base material to be granulated graphite (hereinafter referred to as a granulated carbon material) or is wrapped inside the base material. It becomes possible to granulate. As a result, a granulated carbon material having a high degree of spheroidization, a small amount of fine powder, and sufficiently large pores of 4 nm to 150 nm can be obtained.

  As a method for adjusting the d50 of the raw material carbon material to the above range, for example, there is a method of pulverizing and / or classifying (natural) graphite particles.

  There are no particular restrictions on the apparatus used for pulverization, for example, the coarse pulverizer includes a shearing mill, jaw crusher, impact crusher, cone crusher, etc., and the intermediate pulverizer includes a roll crusher, hammer mill, etc. Examples of the fine pulverizer include a mechanical pulverizer, an airflow pulverizer, and a swirl flow pulverizer. Specific examples include a ball mill, a vibration mill, a pin mill, a stirring mill, a jet mill, a cyclone mill, and a turbo mill. In particular, when obtaining graphite particles having a d50 of 10 μm or less, it is preferable to use an airflow pulverizer or a swirl flow pulverizer.

There is no particular limitation on the apparatus used for classification, but for example, in the case of dry sieving, a rotary sieving, a swaying sieving, a rotating sieving, a vibrating sieving, etc. can be used. In this case, gravity classifier, inertial classifier, centrifugal classifier (classifier, cyclone, etc.) can be used, wet sieving, mechanical wet classifier, hydraulic classifier, sedimentation classifier A centrifugal wet classifier or the like can be used.

  Further, it is preferable that the raw material carbon material obtained in the first step satisfies the following physical properties.

  The surface spacing (d002) of the 002 plane and the crystallite size (Lc) of the raw carbon material by X-ray wide angle diffraction method are usually such that d002 is 3.37 mm or less, Lc is 900 mm or more, and d002 is 3.36 mm. In the following, it is preferable that Lc is 950 mm or more. d002 and Lc are values indicating the crystallinity of the carbon material bulk. The smaller the d002 value and the larger the Lc, the higher the crystallinity of the carbon material. The capacity increases as it approaches the theoretical value. If the crystallinity is too low, excellent battery characteristics such as a high capacity and a low irreversible capacity when high crystalline graphite is used for the electrode tend to be hardly exhibited. It is particularly preferable that d002 and Lc are combined in the above ranges.

  X-ray diffraction is measured by the following method. First, carbon powder was mixed with about 15% by weight of X-ray standard high-purity silicon powder, and the material was CuKα rays monochromatized with a graphite monochromator. The reflection diffractometer method was used. A wide-angle X-ray diffraction curve is measured. Thereafter, the interplanar spacing (d002) and the crystallite size (Lc) are obtained using the Gakushin method.

The filling structure of the raw material carbon material depends on the size, shape, degree of interaction force between particles, etc., but in the present invention, tap density is applied as one of the indicators for quantitatively discussing the filling structure. It is also possible. In the study by the present inventors, it has been confirmed that, in the case of graphite particles having a true density and an average particle diameter substantially equal, the tap density increases as the shape is spherical and the particle surface is smoother. That is, in order to increase the tap density, it is important to keep the particle shape close to a sphere and to keep the particle surface smooth. When the particle shape approaches a spherical shape and the particle surface is smooth, the powder filling property is greatly improved. The tap density of the raw material carbon material is preferably 0.1 g / cm ³ or more, more preferably 0.15 g / cm ³ or more, still more preferably 0.2 g / cm ³ or more, and particularly preferably 0. .3 g / cm ³ or more. The tap density is measured by the method described later in the examples.

The argon ion laser Raman spectrum of the raw carbon material is used as an index indicating the surface properties of the particles. Raman R value is the peak intensity ratio in the vicinity of 1360 cm ^-1 to the peak intensity near 1580 cm ^-1 in the argon ion laser Raman spectrum of the raw carbon material is preferably 0.05 to 0.9, more preferably 0 .05 or more and 0.7 or less, more preferably 0.05 or more and 0.5 or less. The R value is an index representing the crystallinity in the vicinity of the surface of the carbon particle (from the particle surface to about 100 °), and the smaller the R value, the higher the crystallinity or the disordered crystal state. The Raman spectrum is measured by the method shown below. Specifically, the sample particles are naturally dropped into a Raman spectrometer measurement cell, the sample is filled, and the measurement cell is irradiated with an argon ion laser beam, and the measurement cell is placed in a plane perpendicular to the laser beam. Measure while rotating. Note that the wavelength of the argon ion laser light is 514.5 nm.

(2nd process) The process which mixes a raw material carbon material and a granulating agent The granulating agent used by embodiment of this invention is liquid at the process of granulating the said raw material carbon material, 2) The granulating material is non- 3) If the granulating agent does not contain an organic solvent or contains an organic solvent, at least one of the organic solvents does not have a flash point or has a flash point. When it has, the flash point satisfies the condition of 5 ° C. or more.

  By having a granulating agent that satisfies the above requirements, the granulating agent liquid-crosslinks between the raw material carbon materials in the subsequent step of granulating the raw material carbon material in the third step, so that the liquid between the raw material carbon materials. The attractive force generated by the capillary negative pressure in the bridge and the surface tension of the liquid acts as the liquid cross-linking adhesion between the particles, so the liquid cross-linking adhesion between the raw carbon materials increases, and the raw carbon material adheres more firmly. It becomes possible.

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

(Measurement method of contact angle θ with graphite)
Contact angle measurement when 1.2 μL of granulating agent is dropped on the HOPG surface and the wetting spread converges and the change rate of the contact angle θ per second becomes 3% or less (also called steady state). It measures with an apparatus (Kyowa Interface Co., Ltd. automatic contact angle meter DM-501). Here, when using a granulating agent having a viscosity at 25 ° C. of 500 cP or less, the value at 25 ° C. is used, and when using a granulating agent having a viscosity at 25 ° C. of more than 500 cP, the viscosity reaches 500 cP or less. The measured value of the contact angle θ at the heated temperature.

  Furthermore, as the contact angle θ between the raw carbon material and the granulating agent is closer to 0 °, the γ cos θ value increases, so that the liquid-crosslinking adhesion between graphite particles increases and the graphite particles adhere more firmly. It becomes possible. Accordingly, the contact angle θ of the granulating agent with graphite is more preferably 85 ° or less, further preferably 80 ° or less, further preferably 50 ° or less, and more preferably 30 ° or less. It is particularly preferable that the angle is 20 ° or less.

  Even when a granulating agent having a large surface tension (γ) is used, the γ cos θ value is increased and the adhesion of graphite particles is improved. Therefore, γ is preferably 0 or more, more preferably 15 or more, and further preferably 30 or more. It is. The surface tension (γ) of the granulating agent can be measured by a Wilhelmy method using a surface tension meter (for example, DCA-700 manufactured by Kyowa Interface Science Co., Ltd.).

  In addition, a viscous force acts as a resistance component against the elongation of the liquid bridge accompanying the movement of particles, and the magnitude thereof is proportional to the viscosity. For this reason, if it is a liquid at the time of the granulation process which granulates a raw material carbon material, the viscosity of a granulating agent will not be specifically limited, However, It is preferable that it is 1 cP or more at the time of a granulation process.

  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. Particularly preferred. 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 a collision with the rotor or casing when the raw carbon material is granulated.

The viscosity of the granulating agent used in the present invention is measured by using a rheometer (for example, ARES manufactured by Rheometric Scientific Co.), putting an appropriate amount of a measuring object (in this case, a granulating agent) in a cup and adjusting the temperature to a predetermined temperature. When the shear stress at a shear rate of 100 s ⁻¹ is 0.1 Pa or more, the value measured at the shear rate of 100 s ⁻¹ is measured, and when the shear stress at the shear rate of 100 s ⁻¹ is less than 0.1 Pa, measured at 1000 s ⁻¹ . When the shear stress at a shear rate of 1000 s ⁻¹ is less than 0.1 Pa, the shear stress is 0.1.
A value measured at a shear rate of Pa or higher is defined as a viscosity in the present specification. Note that the shear stress can be set to 0.1 Pa or more by making the spindle to be used a shape suitable for a low-viscosity fluid.

  Further, the viscosity of the granulating agent when mixing the raw material carbon material and the granulated material is preferably 1 cP or more and 1000 cP or less, more preferably 5 cP or more and 800 cP or less, and more preferably 10 cP or more and 600 cP or less. More preferably, it is 20 cP or more and 500 cP or less. When the viscosity is within the above range, the granulated material uniformly adheres to the raw carbon material, and when the raw carbon material is granulated, the adhering particles are prevented from being detached due to impact force such as collision with the rotor or casing. In addition, it is possible to reduce the fine pores by the granulation material entering amorphous pores in the 1 nm to 4 nm pores to become amorphous carbon in the subsequent process, and the negative electrode material having excellent low-temperature input / output characteristics and high-temperature storage characteristics Is preferable because it can be manufactured. The viscosity at the time of granulating the raw material carbon material can be adjusted by adding an organic solvent described later and controlling the mixing temperature.

  The granulating agent used in the embodiment of the present invention contains an organic compound that becomes amorphous carbon. Thus, since the granulated material enters amorphous pores into 1 nm to 4 nm and becomes amorphous carbon, the fine pores can be reduced, and thus a negative electrode material excellent in low temperature input / output characteristics and high temperature storage characteristics can be manufactured. For example, petroleum-based or coal-based heavy oil, tar, pitch, polyvinyl alcohol, polyacrylonitrile, phenol resin, cellulose resin, etc. are included, and water-based solvent or flash point is not necessary or flash point if necessary. Can be diluted with a solvent having a flash point of 5 ° C. or higher. Among these, since it is hard to produce micropores as amorphous carbon, and micropores of 1 nm to 4 nm can be reduced more efficiently, petroleum-based or coal-based heavy oil such as soft carbon, tar, pitch, etc. The inclusion is preferred.

  Furthermore, when the granulating agent used in the embodiment of the present invention does not contain an organic solvent or 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. As a result, when granulating the raw material carbon material in the subsequent third step, it is possible to prevent the risk of ignition, fire, and explosion of the granulating agent induced by impact or heat generation, so that it can be stably and efficiently performed. Manufacturing can be carried out.

Organic solvents with a flash point of 5 ° C or higher include paraffinic oils such as liquid paraffin, olefinic oils, naphthenic oils and aromatic oils, vegetable oils, animal aliphatics, esters, Natural oils such as higher alcohols; alkylbenzenes such as xylene, isopropylbenzene, ethylbenzene, and propylbenzene; alkylnaphthalenes such as methylnaphthalene, ethylnaphthalene, and propylnaphthalene; aromatic hydrocarbons such as allylbenzene such as styrene, and allylnaphthalene; Aliphatic hydrocarbons such as octane, nonane and decane; ketones such as methyl isobutyl ketone, diisobutyl ketone and cyclohexanone; esters such as propyl acetate, butyl acetate, isobutyl acetate and amyl acetate; methanol, ethanol, propanol, Nord, isopropyl alcohol, isobutyl alcohol, ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, glycerin and other alcohols; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, Triethylene glycol monobutyl ether, tetraethylene glycol monobutyl ether, methoxypropanol, methoxypropyl-2-acetate, methoxymethylbutanol, methoxybutyl acetate, diethylene glycol dimethyl ether, dipropylene glycol dimethyl ether, diethylene glycol ethyl methyl ether, Glycol derivatives such as reethylene glycol dimethyl ether, tripropylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, ethylene glycol monophenyl ether; ethers such as 1,4-dioxane; dimethylformamide, pyridine, 2-pyrrolidone, N-methyl-2 -Nitrogen-containing organic compounds such as pyrrolidone; Sulfur-containing organic compounds such as dimethyl sulfoxide; Halogen-containing organic compounds such as dichloromethane, chloroform, carbon tetrachloride, dichloroethane, trichloroethane, chlorobenzene, and mixtures thereof. Such a compound having a low flash point is not included. These organic solvents can be used alone as a granulating agent. In the present specification, the flash point can be measured by a known method.

  As a method of mixing the raw carbon material and the granulating agent, for example, a method of mixing the raw carbon material and the granulating agent using a mixer or a kneader, or an organic compound dissolved in a low viscosity diluent solvent (organic solvent). Examples thereof include a method of removing the dilution solvent (organic solvent) after mixing the granulating agent and the raw material carbon material. Among these, since the fine pores of 1 nm to 4 nm can be more efficiently reduced as the amount of the carbonaceous material in the organic compound increases, there is a method of mixing the raw material carbon material and the granulating agent using a mixer or a kneader. preferable. In addition, when the raw material carbon material is granulated in the subsequent third step, the granulation device and the raw material carbon material are added to the granulating apparatus, and the raw material carbon material and the granulating agent are mixed and granulated. The method of performing a process simultaneously is also mentioned.

  The amount of the granulating agent added is preferably 0.1 parts by weight or more, more preferably 1 part by weight or more, still more preferably 3 parts by weight or more, and still more preferably 6 parts by weight or more with respect to 100 parts by weight of the raw 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. Particularly preferred is 50 parts by weight or less, and most preferred is 30 parts by weight or less. Within the above range, problems such as a decrease in spheroidization due to a decrease in adhesion between particles and a decrease in productivity due to adhesion of the raw carbon material to the apparatus are less likely to occur.

(Third step) Step of granulating raw material carbon material (step of spheroidizing raw material carbon material)
The carbon material is preferably one obtained by subjecting the raw material carbon material to a spheroidizing treatment (hereinafter also referred to as granulation) by giving mechanical action such as impact compression, friction, shearing force and the like. Further, the spheroidized graphite is preferably composed of a plurality of scaly or scaly graphites and ground graphite fine powder, and particularly preferably composed of a plurality of scaly graphites.

  The present invention preferably has a granulation step of granulating the raw material carbon material by applying at least one of mechanical energy of impact, compression, friction and shear force. As an apparatus used in this step, for example, an apparatus that repeatedly gives mechanical action such as compression, friction, shearing force including interaction of raw material carbon materials mainly with impact force can be used.

  Specifically, it has a rotor with a large number of blades installed inside the casing, and the rotor rotates at a high speed, so that the raw material carbon material introduced inside is a machine such as impact, compression, friction, shear force, etc. An apparatus that imparts a functional effect and performs surface treatment is preferable. Moreover, it is preferable to have a mechanism that repeatedly gives mechanical action by circulating the raw carbon material.

  As such an apparatus, for example, a hybridization system (manufactured by Nara Machinery Co., Ltd.), kryptron, kryptron orb (manufactured by Earth Technica), CF mill (manufactured by Ube Industries), mechano-fusion system, nobilta, faculty ( Hosokawa Micron Co., Ltd.), Theta Composer (manufactured by Tokuju Kogakusho Co., Ltd.), COMPOSI (manufactured by Nippon Coke Industries), and the like. Among these, a hybridization system manufactured by Nara Machinery Co., Ltd. is preferable.

When processing using the apparatus, for example, the peripheral speed of the rotating rotor is preferably 30.
m / sec or more, more preferably 50 m / sec or more, further preferably 60 m / sec or more, particularly preferably 70 m / sec or more, most preferably 80 m / sec or more, and preferably 100 m / sec or less. Within the above range, it is preferable because the fine powder can be adhered to the base material and enclosed by the base material at the same time as the spheroidization.

  In addition, the treatment that gives mechanical action to the raw carbon material can be performed simply by passing the raw carbon material, but it is preferable to circulate or retain the raw carbon material in the apparatus for 30 seconds or more, More preferably, the treatment is performed by circulating or staying in the apparatus for 1 minute or more, more preferably 3 minutes or more, particularly preferably 5 minutes or more.

  Further, the viscosity of the granulating agent during the step of granulating the raw material carbon material is preferably 1 cP or more, more preferably 5 cP or more, further preferably 10 cP or more, and 20 cP or more. Is preferably 1000 cP or less, more preferably 800 cP or less, still more preferably 600 cP or less, and particularly preferably 500 cP or less. When the viscosity is within the above range, when the raw carbon material is granulated in the presence of the granulating material, it is possible to prevent the adhered particles from being detached due to impact force such as collision with the rotor or casing. The granulated material enters the 1 to 4 nm micropores and becomes amorphous carbon in the subsequent process. This micropore can be reduced, and it is possible to produce a negative electrode material with excellent low-temperature input / output characteristics and high-temperature storage characteristics. This is preferable. The viscosity at the time of granulating the raw carbon material can be adjusted by adding an organic solvent or controlling the granulation temperature.

  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. Examples of other substances include metals that can be alloyed with lithium or oxides thereof, scales, and the like. Examples thereof include flake graphite, scaly graphite, ground graphite fine powder, amorphous carbon, and raw coke. Various types of particle structure negative electrode materials for non-aqueous secondary batteries can be manufactured by granulating together with substances other than the raw carbon material.

  In addition, the raw material carbon material, the granulating agent, and the other substances may be charged all at once into the apparatus, may be sequentially charged separately, or may be continuously charged. In addition, the raw carbon material, the granulating agent and the other substances may be charged simultaneously into the apparatus, may be mixed and may be charged separately. The raw material carbon material, the granulating agent, and the above-mentioned other substances may be mixed simultaneously, or the above-mentioned other substances may be added to the mixture of the raw carbon material and the granulating agent. A raw material carbon material may be added to a mixture of granules. In addition to the particle design, it can be added and mixed separately at an appropriate timing.

  In the spheroidizing treatment of the carbon material, it is more preferable to spheroidize the fine powder generated during the spheroidizing treatment while adhering to the base material and / or enclosing it in the spheroidized particles. By attaching the fine powder generated during the spheronization treatment to the base material and / or spheronizing while encapsulating in the spheroidized particles, the pores of 4 nm to 150 nm are sufficiently large, and the void structure in the particles becomes more dense. The obtained granulated carbon material can be obtained. For this reason, the amount of edges that can be used as Li ion insertion / desorption sites is increased, and the electrolyte is effectively and efficiently spread to the voids in the particles, so that the Li ion insertion / desorption sites in the particles are efficiently Since it can be used, it tends to exhibit good low-temperature output characteristics and cycle characteristics. In addition, the fine powder adhering to the base material is not limited to that generated during the spheronization treatment, and may be adjusted so as to include fine powder at the same time as the scaly graphite particle size adjustment, or added and mixed separately at an appropriate timing. May be.

In order to attach fine powder to the base material and encapsulate it in the spheroidized particles, the adhesion between the flaky graphite particles and the flaky graphite particles, between the flaky graphite particles and the fine powder particles, and between the fine powder particles and the fine powder particles is strengthened. It is preferable. Specific examples of the adhesion force between particles include van der Waals force and electrostatic attraction without intervening inclusions, and physical and / or chemical crosslinking force via interparticle inclusions.

  The van der Waals force becomes [self weight] <[adhesion force] as the average particle diameter (d50) becomes smaller at 100 μm as a boundary. For this reason, the smaller the average particle diameter (d50) of the flaky graphite (raw carbon material) that is the raw material of the spheroidized graphite, the greater the interparticle adhesion force, and the fine powder adheres to the base material and is encapsulated in the spheroidized particles. It is preferable because it tends to be in a state. The average particle diameter (d50) of the flaky graphite is preferably 1 μm or more, more preferably 2 μm or more, further preferably 3 μm or more, preferably 80 μm or less, more preferably 50 μm or less, still more preferably 35 μm or less, particularly preferably. It is 20 μm or less, particularly preferably 10 μm or less, and most preferably 8 μm or less.

  Examples of the physical and / or chemical cross-linking force through interparticle inclusions include physical and / or chemical cross-linking force through liquid inclusions and solid inclusions. Examples of the chemical cross-linking force include the cross-linking force when a covalent bond, an ionic bond, a hydrogen bond, or the like is formed between a particle and an inclusion between particles due to a chemical reaction, sintering, a mechanochemical effect, or the like. .

(4th process) The process of removing a part of granulating agent and organic solvent In this invention, it is preferable to have the process of removing a part of said granulating agent and organic solvent. Examples of the method for removing a part of the granulating agent and the organic solvent include a method of washing with a solvent and a method of volatilizing and decomposing and removing a part of the granulating agent and the organic solvent by heat treatment.

  The heat treatment temperature at this time is preferably 60 ° C. or higher, more preferably 100 ° C. or higher, further preferably 200 ° C. or higher, particularly preferably 300 ° C. or higher, particularly preferably 400 ° C. or higher, and most preferably 500 ° C., preferably Is 1500 ° C. or lower, more preferably 1000 ° C. or lower, and still more preferably 800 ° C. or lower. When the heat treatment temperature is within the above range, the granulating agent can be sufficiently volatilized and decomposed to improve productivity.

  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. When the heat treatment time is within the above range, the granulating agent can be sufficiently volatilized and decomposed to improve productivity.

  The atmosphere of the heat treatment includes an active atmosphere such as an air atmosphere or an inert atmosphere such as a nitrogen atmosphere and an argon atmosphere. When heat treatment is performed at 200 ° C. to 300 ° C., there is no particular limitation, but the heat treatment is performed at 300 ° C. or more. When performing the above, an inert atmosphere such as a nitrogen atmosphere or an argon atmosphere is preferable from the viewpoint of preventing oxidation of the graphite surface.

(Fifth step) Step of attaching a carbonaceous material having lower crystallinity than the raw carbon material to the granulated carbon material In the present invention, a step of attaching a carbonaceous material having lower crystallinity than the raw carbon material to the granulated carbon material Have. According to this step, graphite having an amorphous carbonaceous material on at least a part of the surface is obtained, so that there is little side reaction between the negative electrode for non-aqueous secondary battery using this and the electrolyte solution, high capacity, low temperature A negative electrode material for a non-aqueous secondary battery excellent in input / output characteristics and high-temperature storage characteristics can be obtained.

The amorphous carbonaceous material is attached (composited) to the granulated carbon material by mixing the organic compound that becomes the amorphous carbonaceous material and the granulated carbon material, and in a non-oxidizing atmosphere, preferably nitrogen, argon, It is the process which heats under distribution | circulation of a carbon dioxide etc., and makes an organic compound amorphous carbonization. Specific organic compounds that become amorphous carbonaceous materials include petroleum-based and coal-based heavy oils, tars and pitches, specifically various soft and hard coal-tar pitches and coal-based liquids such as coal liquefied oils. Various oils such as heavy oil, petroleum heavy oil such as crude oil at normal pressure or reduced pressure distillation residue, and cracked heavy oil which is a byproduct of ethylene production by naphtha cracking can be used.

  Moreover, heat treatment pitches such as ethylene tar pitch, FCC decant oil, and Ashland pitch obtained by heat-treating cracked heavy oil can be exemplified. Furthermore, vinyl 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 phenazine and acridine, sulfur ring compounds such as thiophene, and the like. 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 resin, phenol- Examples thereof include thermosetting resins such as formaldehyde resin and polyimide resin; thermosetting resin raw materials such as furfuryl alcohol. Among these, since it is hard to produce micropores as amorphous carbon and micropores of 1 nm to 4 nm can be reduced more efficiently, petroleum-based or coal-based heavy oil, tar, or pitch that is soft carbon is preferable. .

  As a method of mixing the granulated carbon material and the organic compound that becomes the amorphous carbonaceous material, for example, a method of mixing the raw material carbon material and the granulating agent using a mixer or a kneader or a low viscosity diluent solvent ( Examples thereof include a method of removing the diluted solvent (organic solvent) after mixing the granulating agent dissolved in the organic solvent) and the raw material carbon material. Among these, since the fine pores of 1 nm to 4 nm can be more efficiently reduced as the amount of the carbonaceous material in the organic compound increases, there is a method of mixing the raw material carbon material and the granulating agent using a mixer or a kneader. preferable.

  The viscosity of the organic compound that becomes the carbonaceous material when mixing the granulated carbon material and the organic compound that becomes the carbonaceous material is preferably 1 cP or more and 1000 cP or less, more preferably 5 cP or more and 800 cP or less. More preferably, it is 10 cP or more and 600 cP or less, and particularly preferably 20 cP or more and 500 cP or less. When the viscosity is within the above range, the organic compound that becomes a carbonaceous material enters fine pores of 1 nm to 4 nm in the granulated carbon material, and the fine pores can be reduced by forming amorphous carbon by firing. Since it becomes possible to manufacture the negative electrode material excellent in the characteristic and the high temperature storage characteristic, it is preferable.

  The mixing temperature at the time of mixing the granulated carbon material and the organic compound that becomes the carbonaceous material is usually higher than the softening point of the organic compound that becomes the carbonaceous material, preferably higher than the softening point by 10 ° C., more preferably The temperature is 20 ° C. or more higher than the softening point, more preferably 30 ° C. or more, particularly preferably 50 ° C. or more, usually 450 ° C. or less, preferably 250 ° C. or less. If the heating temperature is too low, the viscosity of the organic compound that becomes the carbonaceous material precursor becomes high and mixing becomes difficult and the coating form may become uneven. If the heating temperature is too high, the organic compound that becomes the carbonaceous material precursor Due to volatilization and polycondensation, the viscosity of the mixed system becomes high and mixing becomes difficult and the coating form may become non-uniform.

  The heating temperature (firing temperature) varies depending on the organic compound used for the preparation of the mixture, but is usually 500 ° C. or higher, preferably 600 ° C. or higher, more preferably 700 ° C. or higher. Add carbonaceous material. 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 that of the scaly graphite in the mixture, and the upper limit of the heating temperature is usually 2000 ° C., preferably 1800 ° C., more preferably 1700 ° C, more preferably 1600 ° C.

After performing the treatment as described above, the carbonaceous material composite carbon material can be obtained by appropriately combining crushing, pulverization and classification treatment. Although the shape is arbitrary, the average particle size is usually 2 to 50 μm, preferably 5 to 35 μm, particularly 8 to 30 μm.

[Negative electrode for non-aqueous secondary battery]
A negative electrode for a non-aqueous secondary battery of the present invention (hereinafter sometimes referred to as “negative electrode of the present invention”) includes a current collector and an active material layer formed on the current collector, The active material layer contains the negative electrode material of the present invention.

  In order to produce a negative electrode using the negative electrode material of the present invention, a mixture of a negative electrode material and a binder resin is made into a slurry with an aqueous or organic medium, and if necessary, a thickener is added thereto and applied to a current collector. And then dry.

  As the binder resin, it is preferable to use a resin that is stable with respect to the non-aqueous electrolyte and water-insoluble. For example, rubbery polymers such as styrene / butadiene rubber, isoprene rubber and ethylene / propylene rubber; synthetic resins such as polyethylene, polypropylene, polyethylene terephthalate, polyimide, polyacrylic acid, and aromatic polyamide; Polymers and hydrogenated products thereof, thermoplastic elastomers such as styrene / ethylene / butadiene, styrene copolymers, styrene / isoprene and styrene block copolymers and hydrides thereof; syndiotactic-1,2-polybutadiene, ethylene / Soft resinous polymer such as vinyl acetate copolymer and copolymer of ethylene and α-olefin having 3 to 12 carbon atoms; polytetrafluoroethylene / ethylene copolymer, polyvinylidene fluoride, polypentafluoro Professional Fluorinated polymers such as polyphenylene and poly hexafluoropropylene may be used. As the organic medium, for example, N-methylpyrrolidone and dimethylformamide can be used.

  The binder resin is usually used in an amount of 0.1 parts by weight or more, preferably 0.2 parts by weight or more based on 100 parts by weight of the negative electrode material. By setting the amount of the binder resin used to be 0.1 parts by weight or more with respect to 100 parts by weight of the negative electrode material, the binding force between the negative electrode materials and between the negative electrode material and the current collector is sufficient, and the negative electrode material is transferred from the negative electrode to the negative electrode material. It is possible to prevent a decrease in battery capacity and deterioration in recycling characteristics due to peeling.

  Further, the amount of the binder resin used is preferably 10 parts by weight or less, more preferably 7 parts by weight or less, with respect to 100 parts by weight of the negative electrode material. By reducing the amount of binder resin used to 10 parts by weight or less with respect to 100 parts by weight of the negative electrode material, it is possible to prevent the capacity of the negative electrode from decreasing and to prevent the entry and exit of alkaline ions such as lithium ions into the negative electrode material. The problem can be prevented.

  Examples of the thickener added to the slurry include water-soluble celluloses such as carboxymethyl cellulose, methyl cellulose, hydroxyethyl cellulose and hydroxypropyl cellulose, polyvinyl alcohol, and polyethylene glycol. Among these, carboxymethyl cellulose is preferable. The thickener is preferably used in an amount of usually 0.1 to 10 parts by weight, particularly 0.2 to 7 parts by weight with respect to 100 parts by weight of the negative electrode material.

  As the negative electrode current collector, for example, copper, copper alloy, stainless steel, nickel, titanium, and carbon that are conventionally known to be usable for this purpose may be used. The shape of the current collector is usually a sheet, and it is also preferable to use a surface with irregularities, a net, a punching metal, or the like.

After the slurry of the negative electrode material and the binder resin is applied to the current collector and dried, the density of the active material layer formed on the current collector is increased by pressing to increase the battery per unit volume of the negative electrode active material layer. It is preferable to increase the capacity. Density of the active material layer is preferably in the range of 1.2~1.8g / cm ^3, more preferably 1.3~1.6g / cm ^3. By setting the density of the active material layer to be equal to or higher than the above lower limit value, it is possible to prevent a decrease in battery capacity accompanying an increase in electrode thickness. In addition, by setting the density of the active material layer to be equal to or less than the above upper limit value, the amount of electrolyte solution retained in the voids decreases as the interparticle voids in the electrode decrease, and the mobility of alkali ions such as lithium ions decreases. It is possible to prevent the rapid charge / discharge performance from being reduced.

  The negative electrode active material layer formed using the negative electrode material of the present invention preferably has a pore volume in the range of 10 nm to 100,000 nm by the mercury intrusion method of 0.05 mL / g, preferably 0.1 ml / g or more. Is more preferable. By setting the pore volume to 0.05 mL / g or more, the area in and out of alkali ions such as lithium ions is increased.

[Non-aqueous secondary battery]
The non-aqueous secondary battery of the present invention is a non-aqueous secondary battery including a positive electrode, a negative electrode, and an electrolyte, and uses the negative electrode of the present invention as the negative electrode. In particular, the positive electrode and the negative electrode used in the non-aqueous secondary battery of the present invention are usually preferably lithium ion secondary batteries capable of inserting and extracting Li ions.

  The non-aqueous secondary battery of the present invention can be produced according to a conventional method except that the negative electrode of the present invention is used. In particular, the non-aqueous secondary battery of the present invention is preferably designed to have a value of [negative electrode capacity] / [positive electrode capacity] of 1.01 to 1.5, and 1.2 to 1.4. It is more preferable.

[Positive electrode]
Examples of the positive electrode material serving as the positive electrode active material of the non-aqueous secondary battery of the present invention include a lithium cobalt composite oxide whose basic composition is represented by LiCoO ₂ , a lithium nickel composite oxide represented by LiNiO ₂ , and LiMnO. A lithium transition metal composite oxide such as lithium manganese composite oxide represented by ₂ and LiMn ₂ O ₄ , a transition metal oxide such as manganese dioxide, a mixture of these composite oxides, or the like may be used. Furthermore _{TiS 2, FeS 2, Nb 3} S 4, Mo 3 S 4, CoS 2, V 2 O 5, CrO 3, V 3 O 3, FeO 2, GeO 2 and _{LiNi 0.33 Mn} 0.33 Co _{0 .33} O ₂ , LiFePO _4, or the like may be used.

  A positive electrode can be produced by slurrying a mixture of the positive electrode material and a binder resin with an appropriate solvent, applying the slurry to a current collector, and drying. The slurry preferably contains a conductive material such as acetylene black or ketjen black. Moreover, you may contain a thickener as needed. In addition, as a binder and a thickener, what is well-known for this use, for example, what was illustrated as what is used for manufacture of a negative electrode can be used.

  The blending amount of the conductive material is preferably 0.5 to 20 parts by weight and more preferably 1 to 15 parts by weight with respect to 100 parts by weight of the positive electrode material. Further, the blending amount of the thickener is preferably 0.2 to 10 parts by weight, and more preferably 0.5 to 7 parts by weight with respect to 100 parts by weight of the positive electrode material. Furthermore, the blending amount of the binder resin with respect to 100 parts by weight of the positive electrode material is preferably 0.2 to 10 parts by weight, more preferably 0.5 to 7 parts by weight when the binder resin is slurried with water. When the binder resin is slurried with an organic solvent that dissolves the binder resin such as N-methylpyrrolidone, 0.5 to 20 parts by weight is preferable, and 1 to 15 parts by weight is more preferable.

  Examples of the positive electrode current collector include aluminum, titanium, zirconium, hafnium, niobium and tantalum, and alloys thereof. Among these, aluminum, titanium and tantalum and alloys thereof are preferable, and aluminum and alloys thereof are most preferable.

[Electrolyte]
As the electrolytic solution, a solution in which various lithium salts are dissolved in a conventionally known non-aqueous solvent can be used.

  Examples of the non-aqueous solvent include cyclic carbonates such as ethylene carbonate, fluoroethylene carbonate, propylene carbonate, butylene carbonate and vinylene carbonate, chain carbonates such as dimethyl carbonate, ethylmethyl carbonate and diethyl carbonate, and cyclic esters such as γ-butyrolactone. , Crown ether, 2-methyltetrahydrofuran, tetrahydrofuran, 1,2-dimethyltetrahydrofuran and cyclic ethers such as 1,3-dioxolane, chain ethers such as 1,2-dimethoxyethane, and the like may be used. Usually, a mixture of two or more of these is used. Of these, it is preferable to use a mixture of a cyclic carbonate and a chain carbonate, or another solvent.

  Compounds such as vinylene carbonate, vinyl ethylene carbonate, succinic anhydride, maleic anhydride, propane sultone and diethyl sulfone, difluorophosphates such as lithium difluorophosphate, and the like may be added to the electrolytic solution. Furthermore, an overcharge inhibitor such as diphenyl ether and cyclohexylbenzene may be added.

Examples of the electrolyte dissolved in the non-aqueous solvent include LiClO ₄ , LiPF ₆ , LiBF ₄ , LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiN (CF ₃ CF ₂ SO ₂ ) ₂ , LiN (CF ₃ SO ₂ ) (C ₄ F ₉ SO ₂ ), LiC (CF ₃ SO ₂ ) _{3 and the} like. The concentration of the electrolyte in the electrolytic solution is usually 0.5 to 2 mol / L, preferably 0.6 to 1.5 mol / L.

[Separator]
It is preferable to use a separator interposed between the positive electrode and the negative electrode. As such a separator, it is preferable to use a porous sheet or nonwoven fabric of polyolefin such as polyethylene or polypropylene.

  EXAMPLES Hereinafter, the content of the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples unless it exceeds the gist. In addition, the value of various manufacturing conditions and evaluation results in the following examples has a meaning as a preferable value of the upper limit or the lower limit in the embodiment of the present invention, and the preferable range is the above upper limit or lower limit value. A range defined by a combination of values of the following examples or values of the examples may be used.

<Production of electrode sheet>
Using the negative electrode material of Example or Comparative Example, an electrode plate having an active material layer with an active material layer density of 1.35 ± 0.03 g / cm ³ was produced. Specifically, 50.00 ± 0.02 g of negative electrode material, 50.00 ± 0.02 g of 1 mass% carboxymethylcellulose sodium salt aqueous solution (0.500 g in terms of solid content), and styrene having a weight average molecular weight of 270,000 -Aqueous dispersion of butadiene rubber 1.00 ± 0.05 g (0.5 g in terms of solid content) was stirred for 5 minutes with a hybrid mixer manufactured by Keyence and defoamed for 30 seconds to obtain a slurry.

This slurry was applied to a width of 10 cm using a small die coater made by ITOCHU machining so that the negative electrode material would be 6.00 ± 0.3 mg / cm ² on a 10 μm thick copper foil as a current collector. Then, roll pressing was performed using a roller having 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.

<Production method of non-aqueous secondary battery (laminated battery)>
Produced by the above method, the negative electrode material is 6.00 ± 0.3mg / cm ² to adhere, 4 cm × 3 cm the adjusted electrode sheet such that the density of the active material layer is 1.35 ± 0.03g / cm ³ 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. A laminate type battery was prepared by injecting 200 μl of an electrolytic solution in which LiPF ₆ was dissolved in a mixed solvent of ethylene carbonate, ethyl methyl carbonate, and dimethyl carbonate (volume ratio = 3: 3: 4) to a concentration of 1.2 mol / L. Was made.

<Low temperature output characteristics>
Using the laminate type non-aqueous electrolyte secondary battery produced by the method for producing the non-aqueous electrolyte secondary battery, low temperature output characteristics were measured by the following measuring method.

  For non-aqueous electrolyte secondary batteries that have not undergone charge / discharge cycles, a voltage range of 4.1 V to 3.0 V at 25 ° C., a current value of 0.2 C (the rated capacity with a discharge capacity of 1 hour rate is discharged in 1 hour) 3C for the current value to be 1C, the same applies hereinafter), voltage range of 4.2V to 3.0V, current value of 0.2C (at the time of charging 4.2V constant voltage charging for another 2.5 hours) Implementation) Initial charge and discharge was performed for 2 cycles.

  Furthermore, after charging at a current value of 0.2 C to SOC 50%, in a low temperature environment of −30 ° C., each current value of 1/8 C, 1/4 C, 1/2 C, 1.5 C, 2 C is 2 seconds. Measure the drop in battery voltage after 2 seconds of discharge under each condition, and calculate the current value I that can flow for 2 seconds when the upper limit of charge voltage is 3V. The value calculated by the formula 3 × I (W) was used as the low temperature output characteristic of each battery.

<High temperature storage characteristics>
High temperature storage characteristics were measured by the following measuring method using a laminate type non-aqueous electrolyte secondary battery produced by the above non-aqueous electrolyte secondary battery production method.

  For non-aqueous electrolyte secondary batteries that have not undergone charge / discharge cycles, a voltage range of 4.1 V to 3.0 V at 25 ° C., a current value of 0.2 C (the rated capacity with a discharge capacity of 1 hour rate is discharged in 1 hour) 3C for the current value to be 1C, the same applies hereinafter), voltage range of 4.2V to 3.0V, current value of 0.2C (at the time of charging 4.2V constant voltage charging for another 2.5 hours) Implementation) Initial charge and discharge was performed for 2 cycles.

  Furthermore, after charging at a current value of 0.2 C to SOC 80%, storage processing was performed at 60 ° C. for 2 weeks. Then, after discharging at a current value of 0.2 C, charging and discharging were further performed at a current value of 0.2 C (at the time of charging, constant voltage charging was further performed for 2.5 hours at 4.2 V), and the above five cycles To the discharge capacity after the discharge (the discharge capacity after two cycles at the voltage range of 4.1V to 3.0V, the voltage range of 4.2V to 3.0V and the current value of 0.2C) The ratio of the discharge capacity after storage was expressed in% as the high temperature storage characteristics.

Example 1
A scaly natural graphite having d50 = 100 μm, d (002) = 3.36 Å, (Raman R value) = 0.17 was crushed in a dry swirl flow crusher having a crushing blade and an airflow classification mechanism inside the crushing chamber. Circulating and pulverizing to obtain natural graphite (A1) having d ₅₀ = 8.9 μm, d (002) = 3.36 Å, (Raman R value) = 0.22, and (tap density) = 0.49 g / cm ^3. It was. To 100 g of the obtained natural graphite (A1), 12 g of coal tar (softening point ≦ 25 ° C., flash point of 70 ° C.) is added as a granulating agent, and the mixture is heated and mixed with stirring so that the viscosity of coal tar becomes 80 cP, and granulated. Natural graphite with a uniform agent was obtained. The obtained natural graphite (B1) uniformly impregnated with the granulating agent is charged into a hybridization system NHS-1 manufactured by Nara Machinery Co., Ltd. while being heated, and the mechanical action for 10 minutes at a rotor peripheral speed of 85 m / sec. The spheroidizing process was performed. The obtained spheroidized natural graphite (C1) and coal tar (softening point ≦ 25 ° C., flash point 70 ° C.) as an amorphous carbon precursor were mixed with heat in a mixer so that the viscosity of coal tar was 80 cP. Then, after heat treatment at 1300 ° C. in an inert gas, the fired product was crushed and classified to obtain a negative electrode material in which graphite and amorphous carbon were combined. From the firing yield, it was confirmed that the mass ratio of graphite to amorphous carbon (graphite: amorphous carbon) was 1: 0.05 in the obtained negative electrode material.

SA _a , SA _b , Raman R value, O / C, thermal weight loss rate, circularity, d50, BET-SA, tap density, low-temperature output characteristics and high-temperature storage characteristics of the obtained sample by the above measurement method It was measured. The results are shown in Table-1.

(Example 2)
Negative electrode in which graphite and amorphous carbon are combined in the same manner as in Example 1 except that the mass ratio of graphite and amorphous carbon (graphite: amorphous carbon) is 1: 0.065. The material was obtained. Table 1 shows the results of measurements performed in the same manner as in Example 1.

(Example 3)
A negative electrode in which graphite and amorphous carbon are combined in the same manner as in Example 1 except that the mass ratio of graphite to amorphous carbon (graphite: amorphous carbon) is 1: 0.08. The material was obtained. Table 1 shows the results of measurements performed in the same manner as in Example 1.

Example 4
100 g of natural graphite (A1) is added with 12 g of coal tar pitch having a softening point of 70 ° C. as a granulating agent, mixed with heating and stirring so that the viscosity of the coal tar pitch becomes 350 cP, and the natural graphite with the granulating agent uniformly attached (B2) was obtained. The obtained natural graphite (B2) uniformly attached with the granulating agent is put into a hybridization system NHS-1 manufactured by Nara Machinery Co., Ltd. in a heated state, and mechanical action is performed for 10 minutes at a rotor peripheral speed of 85 m / sec. The spheroidizing process was performed. The obtained spheroidized natural graphite (C2) and a coal tar pitch having a softening point of 70 ° C. as an amorphous carbon precursor were mixed by heating so that the viscosity of the coal tar pitch was 350 cP, After heat treatment at 1300 ° C., the fired product was crushed and classified to obtain a negative electrode material in which graphite and amorphous carbon were combined. From the firing yield, it was confirmed that the mass ratio of graphite and amorphous carbon (graphite: amorphous carbon) was 1: 0.08 in the obtained negative electrode material. Table 1 shows the results of measurements performed in the same manner as in Example 1.

(Comparative Example 1)
The spheroidized natural graphite having a d50 of 100 μm is spheroidized by a mechanical action for 10 minutes at a rotor peripheral speed of 85 m / sec using a hybrid system NHS-1 manufactured by Nara Machinery Co., Ltd., and natural graphite (a1) is obtained. Obtained. The obtained natural graphite (a1) has a large amount of flaky graphite fine powder not attached to the base material of spheroidized graphite and flaky graphite fine powder not contained in the spheroidized graphite. Was confirmed. This natural graphite (a1) was classified, and the above scale-like graphite fine powder was removed to obtain spheroidized graphite (c1) having a d50 of 10.8 μm and a tap density of 0.88 g / cm ³ . Coal tar (softening point ≦ 25 ° C., flash point 70 ° C.) as a carbonaceous precursor having lower crystallinity than the obtained spheroidized graphite and raw material graphite is heated for 20 minutes with a mixer so that the viscosity of the coal tar pitch becomes 350 cP. After mixing and heat-treating at 1300 ° C. in an inert gas, the fired product was crushed and classified to obtain a multilayered graphite in which graphite and amorphous carbonaceous material were compounded. From the firing yield, it was confirmed that the mass ratio of the granulated graphite and the amorphous carbonaceous material (granulated graphite: amorphous carbon) was 1: 0.065 in the obtained multilayer structure graphite. . Table 1 shows the results of measurements performed in the same manner as in Example 1.

(Comparative Example 2)
Natural graphite (A1) 100g natural paraffinic oil (liquid paraffin, manufactured by Wako Pure Chemical Industries, grade 1, flash point 238 ° C) 12g as a granulating agent, stirred and mixed, the granulating agent uniformly attached Graphite (b2) was obtained. The obtained natural graphite (b2) with the granulating agent uniformly applied is put into the Nara Machinery Hybridization System NHS-1 type, and the spheroidizing treatment is performed by mechanical action for 10 minutes at a rotor peripheral speed of 85 m / sec. went. The obtained spheroidized natural graphite (c2) and a coal tar pitch having a softening point of 70 ° C. as an amorphous carbon precursor were mixed by heating so that the viscosity of the coal tar pitch was 60 cP, After heat treatment at 1300 ° C., the fired product was crushed and classified to obtain a carbon material in which graphite and amorphous carbon were combined. From the firing yield, it was confirmed that the mass ratio of graphite to amorphous carbon (graphite: amorphous carbon) was 1: 0.08 in the obtained carbon material. The results of measurements similar to those in Example 1 are shown in Table 1.

(Comparative Example 3)
After the spheroidized natural graphite (C1) was heat treated at 1300 ° C., the fired product was crushed and classified to obtain a multilayer structure carbon material in which graphite particles and amorphous carbon were combined. . The results of measurements similar to those in Example 1 are shown in Table 1.

[Evaluation results]
As is clear from Table 1, Comparative Example 1 was excellent in high temperature storage characteristics, but the value of SA _b / SA _a was small and the low temperature input / output characteristics were poor. Further, Comparative Examples 2 and 3 are excellent low-temperature output characteristics, the value of SA _a large, poor high temperature storage characteristics. In contrast to these results, in Examples 1 to 4 corresponding to the negative electrode material of the present invention, both the low temperature input / output characteristics and the high temperature storage characteristics were good.

  The negative electrode material for a non-aqueous electrolyte secondary battery of the present invention, and the negative electrode and non-aqueous secondary battery for a non-aqueous secondary battery including the same are used in in-vehicle applications, power tool applications, capacity and high temperature, which emphasize low-temperature input / output characteristics. It can be suitably used for mobile device applications such as mobile phones and personal computers that place importance on storage characteristics.

Claims (10)

Corresponding to a surface area (SA _a ) corresponding to pores of 1 nm to 4 nm and pores of 4 nm to 150 nm in pore distribution required by the nitrogen adsorption method, including graphite having amorphous carbon on at least a part of the surface A negative electrode material for a non-aqueous secondary battery satisfying the following conditions (1) and (2) with respect to the surface area (SA _b ) to be produced.
Condition (1): SA _a is 1.80 m ² / g or less.
Condition (2): SA _b / SA _a is 1.30 or more. The negative electrode material for a non-aqueous secondary battery according to claim 1, wherein the pore distribution satisfies the following condition (3).
Condition (3): SA _a is 1.50 m ² / g or more. The negative electrode material for nonaqueous secondary batteries according to claim 1 or 2, wherein the Raman R value represented by the following formula is 0.20 or more.
[Raman R value] = [Intensity I _B of peak P _B near 1360 cm ⁻¹ in Raman spectral analysis] / [Intensity I _A of peak P _A near 1580 cm ⁻¹ ]   The carbon material for non-aqueous secondary batteries according to any one of claims 1 to 3, wherein the surface functional group amount O / C value obtained by X-ray photoelectron spectroscopy (XPS) is 3 mol% or less.   The carbon material for a non-aqueous secondary battery according to any one of claims 1 to 4, wherein a rate of decrease in thermal weight between 200 ° C and 600 ° C determined by a differential thermobalance is 1% or less.   The negative electrode material for a non-aqueous secondary battery according to any one of claims 1 to 5, wherein the circularity determined by flow particle image analysis is 0.88 or more.   The negative electrode material for a non-aqueous secondary battery according to any one of claims 1 to 6, comprising spheroidized graphite as the graphite.   The mass ratio of the amorphous carbon to the graphite ([[amorphous carbon mass] / [graphite mass]] × 100) is 0.1% or more and 30% or less. The negative electrode material for non-aqueous secondary batteries according to any one of the above items.   A nonaqueous secondary battery comprising a current collector and an active material layer formed on the current collector, wherein the active material layer contains the negative electrode material according to any one of claims 1 to 8. Negative electrode. A nonaqueous secondary battery comprising a positive electrode and a negative electrode, and an electrolyte, wherein the negative electrode is a negative electrode for a nonaqueous secondary battery according to claim 9.

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