JP2019175775A - Negative electrode material for non-aqueous secondary battery, negative electrode for non-aqueous secondary battery, and non-aqueous secondary battery - Google Patents

Abstract

To provide a negative electrode material for a non-aqueous secondary battery excellent in low temperature output characteristic and high temperature storage characteristic, and a negative electrode for a non-aqueous secondary battery and a non-aqueous secondary battery including the negative electrode material.SOLUTION: A negative electrode material for a non-aqueous secondary battery is a spheroidized graphite in which a graphite material is compounded, and a pellet density is 1.10 to 1.60 g/cc or less.SELECTED DRAWING: None

Description

The present invention relates to a negative electrode material for a non-aqueous secondary battery excellent in low temperature output characteristics and high temperature 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 LiPF ₆
And non-aqueous lithium secondary batteries made of a non-aqueous electrolyte in which a lithium salt such as LiBF ₄ is 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.

In Patent Document 1, even when the negative electrode material in which the graphite particles and the graphitized material of the graphitizable binder are combined densifies the active material layer on the negative electrode current collector, charge / discharge during the initial cycle is performed. It is disclosed that the irreversible capacity is small and the load characteristics after charge / discharge are excellent.

In addition, various graphite-based carbon materials are used as the negative electrode material. Further, as an improvement of the processing process of graphite itself, Patent Document 2 discloses that the accumulated pore volume of the carbon material is within a specific range. In addition, it is disclosed that those having a pore diameter / volume-based average particle diameter ratio (PD / d50 (%)) in a specific range are excellent in low-temperature output characteristics.

International Publication No. 08/084675 International Publication No. 16/006617

According to the study by the present inventors, the negative electrode material for non-aqueous secondary batteries described in Patent Document 1 has been found to have a problem that the low-temperature output characteristics are insufficient. In addition, the negative electrode material for non-aqueous secondary batteries described in Patent Document 2 has a problem that the high-temperature storage characteristics are insufficient because the surface area derived from micropores having a specific diameter that adversely affects high-temperature storage is high. I found out. That is, the object of the present invention is to provide a negative electrode material for a non-aqueous secondary battery excellent in low-temperature output characteristics and high-temperature storage characteristics,
Another object is to provide a negative electrode for a non-aqueous secondary battery and a non-aqueous secondary battery including the same.

As a result of intensive studies to solve the above problems, the present inventors are able to solve the above problems with a negative electrode material for non-aqueous secondary batteries which is a spheroidized graphite in which a graphite material is compounded and has specific physical properties. I found. That is, the gist of the present invention is as follows.

[1] Spherical graphite in which a graphite material is combined, and the pellet density is 1.10 to 1.60.
The negative electrode material for non-aqueous secondary batteries which is g / cc or less.

[2] The negative electrode material for a non-aqueous secondary battery according to [1], wherein the relationship between the pellet density and the volume-based average particle diameter (d50) satisfies the following formula (1).
Formula (1)
[Pellet density (g / cc)] ≦ 0.0138 × [d50 (μm)] + 1.42

[3] The negative electrode material for a non-aqueous secondary battery according to [1] or [2], wherein the volume-based average particle diameter (d50) is 4 to 30 μm.

[4] The negative electrode material for a non-aqueous secondary battery according to any one of [1] to [3], which has a Raman R value of 0.25 or less.

[5] At least a part of the spheroidized graphite is coated with a graphite material. [1]
Thru | or the negative electrode material for non-aqueous secondary batteries as described in any one of [4].

[6] The negative electrode material for a non-aqueous secondary battery according to any one of [1] to [5], wherein the spheroidized graphite includes natural graphite.

[7] [Tap density (g / cc)] / [specific surface area (m ² / g)] is 0.25 to 1.25, according to any one of [1] to [6] Negative electrode material for water-based secondary batteries.

[8] Any one of [1] to [7], wherein the tap density is 0.80 to 1.50 g / cc.
The negative electrode material for non-aqueous secondary batteries described in 1.

[9] The negative electrode material for a non-aqueous secondary battery according to any one of [1] to [8], which has a specific surface area of 1.00 to 12.0 m ² / g.

[10] A negative electrode for a non-aqueous secondary battery comprising a current collector and an active material layer formed on the current collector, wherein the active material layer is any one of [1] to [9] A negative electrode for a non-aqueous secondary battery, comprising the negative electrode material for a non-aqueous secondary battery described in 1.

[11] A non-aqueous secondary battery comprising a positive electrode, a negative electrode, and an electrolyte, wherein the negative electrode is [10
] The nonaqueous secondary battery which is a negative electrode for nonaqueous secondary batteries as described in above.

ADVANTAGE OF THE INVENTION According to this invention, the negative electrode material for non-aqueous secondary batteries excellent in the low temperature output characteristic and the high temperature storage characteristic, and the negative electrode for non-aqueous secondary batteries and a non-aqueous secondary battery containing this are provided.

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”) is spheroidized graphite in which a graphite material is compounded, and the pellet density is 1.10. ~ 1.6
0 g / cc.

The negative electrode material for a non-aqueous secondary battery according to the present invention has an effect of being able to achieve both high capacity, low temperature input / output characteristics and high temperature storage characteristics 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 in the graphite are formed by the graphite material when the graphite and the graphite material are combined. As a result, the low-temperature input / output characteristics deteriorate due to the inhibition of Li ion insertion / desorption on the surface of the negative electrode material in these pores. Furthermore, during storage at high temperatures, the electrolyte contacts the surfaces of 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 many Li ion insertion / desorption sites, and at least a part of graphite excellent in Li ion insertion / desorption reactivity is coated with a graphite material, so that low-temperature input / output characteristics can be obtained. Is estimated to improve. In particular, in the negative electrode material in which graphite and a graphite material are combined, the pellet density in the above specific range means that it has a denser structure, and as a result, even when stored at high temperatures, It is presumed that decomposition side reaction does not occur in order to prevent the electrolyte from entering, and the high temperature storage characteristics are improved. These results
It is estimated that both low temperature input / output characteristics and high temperature storage characteristics can be achieved.

[graphite]
The negative electrode material of the present invention contains graphite having a graphite material on at least a part of its surface. When used in a lithium ion secondary battery, the graphite is not particularly limited as long as it has a graphite material on at least a part of its surface, but it is preferable to use a material capable of occluding and releasing lithium ions. . Specific examples of graphite include scale-like, massive or plate-like natural graphite, petroleum coke, coal pitch coke, coal needle coke, and mesophase pitch.
Examples thereof include artificial graphite produced by heating to 500 ° C. or higher.

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. Used and mixed, usually 2500 ° C ~ 3 in non-oxidizing atmosphere
By baking at 300 ° C., preferably 2600 ° C. to 3200 ° C., more preferably 2700 to 3100 ° C., at least a part of the spheroidized graphite is coated with the graphite, and preferably at least part of the spheroidized graphite is coated with the graphite. Graphite can be obtained. The negative electrode material of the present invention further improves the high-temperature storage characteristics by using spheroidized graphite in which such a graphite material is combined.

In particular, in the negative electrode material of the present invention, the mass ratio of graphite to graphite is ([[mass of graphite]
/ [Mass of graphite] × 100) is preferably 0.1% or more, more preferably 1% or more,
More preferably, it is 3% or more, particularly preferably 5% or more, and most preferably 6% or more.
On the other hand, it is preferably 50% or less, more preferably 45% or less, and still more preferably 40% or less. If the mass ratio is within the above range, the low temperature output characteristics and the specific surface area that affects high temperature storage tend to be reduced, which is preferable in terms of achieving both low temperature input / output characteristics and high temperature storage characteristics. 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 range of pellet density. The negative electrode material of the present invention is
It is preferable that the following physical properties are satisfied.

<Pellet density>
The negative electrode material of the present invention is 1.10 g / cc or more from the viewpoint of high temperature storage characteristics, and 1.60 g / cc or less from the viewpoint of low temperature output characteristics. From the viewpoint of making these more favorable, the pellet density of the negative electrode material of the present invention is preferably 1.20 g / cc or more, and 1.30.
g / cc or more is more preferable, 1.40 g / cc or more is further preferable, 1.45 g / cc or more is particularly preferable, and 1.58 g / cc or less is preferable. More preferably, it is 1.56 g / cc or less. In the present invention,
The pellet density of the negative electrode material can be measured by the following method.

Load and height when sandwiched after inserting two kinds of jigs: φ10, 35 mm long shaft and φ10, 6 mm long shaft as receiving jig into a mold with inner diameter φ10
(Thickness measurement system manufactured by Mitsubishi Chemical Analytech)
And apply a load of 15 kgf with a hydraulic pump, and measure the jig height. Next, only the pushing jig is taken out, 0.6 g of composite particles are added, and the pushing jig is inserted again. Set the mold hydraulic jack (e.g. AS ONE manufactured by High Pressure Jack J-1), slowly pressurized to 882kgf / cm ² by tightening the pressure valve after pressure quickly warm to 2426kgf / cm ^2, holding for 3 seconds Release the hydraulic jack, wait 60 seconds, loosen the pressure valve and reduce the pressure. After that, set the load and height on the device that can be measured again.
A load of 5 kgf is applied and the jig height after pressurization is measured. In addition, the weight of the composite particles after pressurization is measured, and the density calculated from the difference between the jig height and the weight is defined as the pellet density.

<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. Also, 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.
It is as follows. 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 as a measurement sample into a commercially available laser diffraction / scattering type particle size distribution measuring apparatus (for example, LA-920 manufactured by HORIBA).
It is defined as a volume-based median diameter measured by the measurement apparatus after irradiating an 8 kHz ultrasonic wave at an output of 60 W for 1 minute.

<Relationship between pellet density and volume-based average particle diameter (d50)>
In the negative electrode material of the present invention, the relationship between the pellet density and the volume-based average particle diameter (d50) preferably satisfies the following formula (1) from the viewpoint of achieving both low temperature input / output characteristics and high temperature storage characteristics. Also,
The negative electrode material of the present invention more preferably satisfies the formula (1-1) for the same reason, and the formula (1-2)
It is more preferable to satisfy | fill.
Formula (1)
[Pellet density (g / cc)] ≦ 0.0138 × [d50 (μm)] + 1.42
Formula (1-1)
[Pellet density (g / cc)] ≦ 0.0138 × [d50 (μm)] + 1.41
Formula (1-2)
[Pellet density (g / cc)] ≦ 0.0138 × [d50 (μm)] + 1.40

<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, 1360 cm
The intensity _{I B} of the vicinity of the peak _{P B} ^-1 is defined as the intensity ratio as measured _(I B / I _A). “Near 1580 cm ⁻¹ ” means a range of 1580 to 1620 cm ⁻¹ , “13
The 60cm around ^-1 "refers to the range of 1350 ^-1.

The Raman R value of the negative electrode material of the present invention is preferably 0.01 or more, more preferably 0.02 or more, still more preferably 0.03 or more, and particularly preferably 0.05 or more. Usually 0
. 25 or less, preferably 0.20 or less, more preferably 0.17 or less, still more preferably 0
. 15 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 increases and the side reaction with the electrolyte increases, leading to a decrease in the initial charge / discharge efficiency of the lithium ion secondary battery and an increase in the amount of gas generated. There is a tendency 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)

<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. .9g / cm ³ or more, most preferably 0.93 g / cm ³ or more, preferably 1
. 5 g / cm ³ or less, more preferably 1.4 g / cm ³ or less, further preferably 1.3 g / cm 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 it is not more than the upper limit.

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 preferably has a specific surface area (BET-SA) by the BET method of 1 m ² /
g or more, more preferably 1.5 m ² / g or more, still more preferably 2 m ² / g or more, particularly preferably 2.5 m ² / g or more, while preferably 12 m ² / g or less, more preferably It is 10 m ² / g or less, more preferably 8 m ² / g or less, particularly preferably 6 m ² / g or less. 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 a nitrogen flow, and then cooled to the liquid nitrogen temperature, and the value of the relative pressure of nitrogen with respect to atmospheric pressure was 0.00.
Using a nitrogen helium mixed gas adjusted to be 3 accurately, measurement can be performed by a nitrogen adsorption BET one-point method using a gas flow method.

[Production method]
The negative electrode material for a non-aqueous secondary battery of the present invention is a spheroidized graphite in which a graphite material is compounded, and can be manufactured so that the pellet density is in a specific range. Although there is no particular limitation, as a specific example, flaky natural graphite having a particle size adjusted so that d50 is 80 μm or less and adjusted to have a fine pore amount of 1 nm to 150 nm is spheroidized (granulated in the presence of a granulating agent). ) The spheronization treatment is performed while the fine powder generated during the treatment adheres to the base material which becomes the spheroidized graphite (hereinafter sometimes referred to as spheroidized graphite) and / or is encapsulated in the particles of the spheroidized graphite. By doing so, spheroidized graphite having a dense particle structure is obtained. Thereafter, the structure is further densified by coating with an organic compound as a raw material for the graphite material, and a method of adjusting the pellet density to a predetermined range can be mentioned.

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) A granulating agent is a liquid at the time of granulating the said raw material carbon material.
2) The granulating agent contains a liquid organic compound.
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 adhering a graphite 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.
m or more, more preferably 3 μm or more. On the other hand, it is preferably 80 μm or less, more preferably 50 μm or less, still more preferably 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. Moreover, when d50 is in the above range, the fine powder generated during the granulation step is reduced to granulated graphite (
Hereinafter, it is referred to as a granulated carbon material. It is possible to perform granulation while adhering to or enclosing the base material. 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 value of d002 and the larger Lc,
This indicates that the carbon material has high crystallinity, and the capacity increases because the amount of lithium entering the graphite layer approaches the theoretical value. If the crystallinity is too low, high capacity when using high crystalline graphite for the electrode,
In addition, excellent battery characteristics such as low irreversible capacity 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 carbon material is preferably 0.1 g /
cm ³ or more, more preferably 0.15 g / cm ³ or more, and still more preferably 0.
It is 2 g / cm ³ or more, 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 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
3) When the granulating agent contains a liquid organic compound, and 3) 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 is flammable. When it has a point, it is preferable that the flash point satisfies the condition of 5 ° C. or higher.

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)
When 1.2 μL of granulating agent is dropped on the HOPG surface, the wetting spread converges and the contact angle θ for one second
The contact angle when the change rate of 3% or less (also referred to as a steady state) is measured with a contact angle measuring device (automatic contact angle meter DM-501 manufactured by Kyowa Interface Co., Ltd.). Here, the viscosity at 25 ° C. is 50
When a granulating agent of 0 cP or less is used, the value at 25 ° C. is set so that the viscosity at 25 ° C. is 500.
When a granulating agent larger than cP is used, the measured value of the contact angle θ at a temperature heated to a temperature at which the viscosity is 500 cP or less is used.

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. Therefore, the contact angle θ of the granulating agent with graphite is more preferably 85 ° or less, further preferably 80 ° or less, and further preferably 50 ° or less,
It is particularly preferably 30 ° or less, and most preferably 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 granule has a viscosity at 25 ° C. of preferably 1 cP or more and 100,000 cP or less, more preferably 5 cP or more and 10,000 cP or less, and more preferably 10 cP or more and 8000 c.
P or less is more preferable, and 50 cP or more and 6000 cP or less is particularly preferable. When the viscosity is within the above range, it is possible to prevent the adhered particles from being detached due to an impact force such as 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 a rheometer (for example, Rheometric Sc.
A measurement target (a granulating agent in this case) is put in a cup using AENT) and measured at a predetermined temperature. The shear stress at a shear rate of 100 s ⁻¹ is 0.
In the case of 1 Pa or more, the value measured at a shear rate of 100 s ⁻¹ is used as the shear rate of 100 s ^−1.
Shear stress when the shear stress is less than 0.1Pa a value measured by 1000 s ^-1 when the shear stress is less than 0.1Pa, at a shear rate of 1000 s ^-1 in 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.

The viscosity of the granulating agent when mixing the raw material carbon material and the granulating material is 1 cP or more and 1000 cP.
Is preferably 5 cP or more and 800 cP or less, more preferably 10 cP or less.
More preferably, it is 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 granulated material uniformly adheres to the raw carbon material,
When granulating raw material carbon material, it is possible to prevent adhesion particles from detaching due to impact force such as collision with rotor or casing, and to produce negative electrode material with excellent low temperature input / output characteristics and high temperature storage characteristics Is preferable. 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 a liquid organic compound. Thereby, since a micropore can be reduced and the value of a pellet density tends to become lower, the negative electrode material excellent in the low temperature input / output characteristic and the high temperature storage characteristic 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.

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; xylene, isopropylbenzene,
Alkylbenzenes such as ethylbenzene and propylbenzene; alkylnaphthalenes such as methylnaphthalene, ethylnaphthalene and propylnaphthalene; allylbenzenes such as styrene;
Aromatic hydrocarbons such as 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, amyl acetate; methanol,
Ethanol, propanol, butanol, 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 Glycol derivatives such as ethyl ethyl ether, triethylene glycol dimethyl ether, tripropylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, ethylene glycol monophenyl ether; ethers such as 1,4-dioxane; dimethylformamide, pyridine, 2- Nitrogen-containing organic compounds such as pyrrolidone and N-methyl-2-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 And a compound having a low flash point such as toluene 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 structure of the spheroidized graphite can be densified, a method of mixing the raw carbon material and the granulating agent using a mixer or a kneader is 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 a granulating agent, it becomes possible to prevent the adhered particles from being detached due to impact force such as collision with the rotor or casing. The structure of the spheroidized graphite is densified, and the final density of the negative electrode material tends to decrease the pellet density, making it possible to produce a negative electrode material with excellent low-temperature input / output characteristics and high-temperature storage characteristics. Therefore, it 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 spheroidizing treatment to the base material and / or encapsulating it in the spheroidized particles, the spheroidizing treatment is performed.
It is possible to obtain a granulated carbon material having sufficiently large pores of nm to 150 nm and a finer pore structure within the particle. 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 distributed to the voids in the particles.
Since ion insertion / desorption sites can be used efficiently, there is a tendency 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 decreases as the average particle diameter (d50) decreases with 100 μm as the boundary [
Self-weight] <[Adhesion]. 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 100 ° C.
0 ° C. or lower, 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.

(5th process) The process of adhering a graphite material to a granulated carbon material In this invention, it has the process of adhering a graphite material to a granulated carbon material. According to this process, since graphite having a graphite material on at least a part of the surface is obtained, there is little side reaction between the negative electrode for a non-aqueous secondary battery using this and the electrolytic solution, and high capacity and excellent high temperature storage characteristics are obtained. In addition, a negative electrode material for a non-aqueous secondary battery can be obtained.

The addition (combination) of the graphite material to the granulated carbon material involves mixing the organic compound that becomes the graphite material and the granulated carbon material, and in a non-oxidizing atmosphere, preferably under the flow of nitrogen, argon, carbon dioxide, etc. Is a treatment for converting the organic compound into a graphite material. Specific organic compounds that become graphite materials include petroleum-based and coal-based heavy oils, tars and pitches, specifically carbon-based heavy oils such as various soft to hard coal tar pitches and coal liquefied oils. Various oils such as petroleum heavy oil such as crude oil at normal or reduced pressure distillation residue and cracked heavy oil which is a by-product 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 resins, phenol- Examples thereof include thermosetting resins such as formaldehyde resin and polyimide resin; thermosetting resin raw materials such as furfuryl alcohol. Among these, petroleum-based and coal-based heavy oil, tar, and pitch, which are soft carbons, are preferable.

As a method of mixing the granulated carbon material and the organic compound that becomes the graphite material, for example, a method of mixing the raw 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 can be more efficiently reduced as the amount of the graphite compound in the organic compound increases, a method of mixing the raw carbon material and the granulating agent using a mixer or a kneader is preferable.

In addition, when the granulated carbon material and the organic compound that becomes the graphite material are mixed, the viscosity of the organic compound that becomes the graphite material is preferably 1 cP or more and 1000 cP or less, preferably 5 cP or more and 800 cP.
It is more preferably P or less, further preferably 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 fine pores of the granulated carbon material enter into the fine pores of the granulated carbon material, and the fine pores can be reduced by becoming a graphitic matter by firing and graphitization. It is preferable because a negative electrode material excellent in resistance can be produced.

The mixing temperature at the time of mixing the granulated carbon material and the organic compound that becomes the graphite is usually not lower than the softening point of the organic compound, preferably higher than the softening point by 10 ° C., more preferably 20 ° C. higher than the softening point. It is carried out at a higher temperature, more preferably at a temperature of 30 ° C. or higher, particularly preferably at a temperature of 50 ° C. or higher, usually 450 ° C. or lower, preferably 250 ° C. or lower. If the heating temperature is too low, the viscosity of the organic compound that becomes the graphite precursor may become high, making mixing difficult and the coating form non-uniform, and if the heating temperature is too high, the organic compound that becomes the graphite precursor Volatilization and polycondensation may increase the viscosity of the mixed system and make the coating form non-uniform.

The heating temperature (firing temperature) varies depending on the organic compound used to prepare the mixture, but is usually 25.
It is heated to 00 ° C. or higher, preferably 2600 ° C. or higher, more preferably 2700 ° C. or higher, to attach the graphite material to at least a part of the graphite surface. 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 33000 ° C, preferably 3200 ° C, more preferably 3100 ° 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]
The negative electrode for a non-aqueous secondary battery of the present invention (hereinafter, may be referred to as “the negative electrode of the present invention”).
A current collector and an active material layer formed on the current collector are provided, and 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 Fluorinated polymers such as propylene and polyhexafluoropropylene can be used. As the organic medium, for example, N-methylpyrrolidone and dimethylformamide can be used.

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

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 a negative electrode current collector, it is conventionally known that it can be used for this purpose, for example, copper,
Copper alloy, stainless steel, nickel, titanium, carbon, or the like 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.

10 nm to 1000 nm of a negative electrode active material layer formed using the negative electrode material of the present invention by a mercury intrusion method.
The pore volume in the range of 00 nm is preferably 0.05 mL / g, 0.1 ml / g
More preferably. 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]
As a positive electrode material that becomes an active material of the positive electrode of the non-aqueous secondary battery of the present invention, for example, the basic composition is L
lithium transition metal composite oxides such as lithium cobalt composite oxide represented by iCoO ₂ , lithium nickel composite oxide represented by LiNiO ₂ , lithium manganese composite oxide represented by LiMnO ₂ and LiMn ₂ O ₄ , A transition metal oxide such as manganese, a composite oxide mixture thereof, 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 with respect to 100 parts by weight of the positive electrode material.
5 parts by weight is more preferred. The blending amount of the thickener is 0.2 to 100 parts by weight of the positive electrode material.
10 parts by weight is preferable, and 0.5 to 7 parts by weight is more preferable. 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 ethylene carbonate, fluoroethylene carbonate,
Cyclic carbonates such as propylene carbonate, butylene carbonate and vinylene carbonate, chain carbonates such as dimethyl carbonate, ethyl methyl carbonate and diethyl carbonate, cyclic esters such as γ-butyrolactone, crown ethers, 2-
Cyclic ethers such as methyltetrahydrofuran, tetrahydrofuran, 1,2-dimethyltetrahydrofuran and 1,3-dioxolane, and chain ethers such as 1,2-dimethoxyethane 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 , and 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) and _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>
An electrode plate having an active material layer with an active material layer density of 1.50 ± 0.03 g / cm ³ is prepared using the negative electrode material of the example or the comparative example. Specifically, the negative electrode material 50.00 ± 0.02 g, 1% by mass
50.00 ± 0.02 g of sodium carboxymethylcellulose aqueous solution (0.500 g in terms of solid content) and 1.00 ± 0.05 g of a styrene / butadiene rubber aqueous dispersion having a weight average molecular weight of 270,000 (0 in terms of solid content) 5 g) is stirred with a KEYENCE hybrid mixer for 5 minutes and degassed for 30 seconds to obtain a slurry.

This slurry was placed on a copper foil having a thickness of 10 μm as a current collector, and the negative electrode material was 9.00 ± 0.3.
Use a small die coater made by ITOCHU machining so that the mg / cm ² adheres.
And the density of the active material layer is 1.50 by roll pressing using a roller having a diameter of 20 cm.
An electrode sheet is obtained by adjusting to ± 0.03 g / cm ³ .

<Production method of non-aqueous secondary battery (laminated battery)>
Produced by the above method, the negative electrode material is 9.00 ± 0.3mg / cm ² to adhere, 4 cm × 3 cm the adjusted electrode sheet such that the density of the active material layer is 1.50 ± 0.03g / cm ³ A positive electrode made of NMC is cut out in the same area, and a separator (made of a porous polyethylene film) is placed between the negative electrode and the positive electrode and combined. In a mixed solvent of ethylene carbonate and ethyl methyl carbonate (volume ratio = 3: 7), 1.2 mol of LiPF ₆ was added.
/ L, 200 μL of an electrolytic solution in which vinylene carbonate is dissolved to 1% by weight is injected to prepare a laminate type battery.

<Low temperature output characteristics>
The low temperature output characteristics are measured by the following measurement method using the laminate type non-aqueous electrolyte secondary battery produced by the method for producing the non-aqueous electrolyte secondary battery.

A non-aqueous electrolyte secondary battery that has not undergone a charge / discharge cycle, a voltage range of 4.1 V at 25 ° C.
~ 3.0V, current value 0.2C (the rated capacity due to discharge capacity at 1 hour rate is 1C, the current value for discharging in 1 hour is 1C, the same shall apply hereinafter), 3 cycles, voltage range 4.2V-3.0V , Current value 0
. 2 cycles at 2C (at the time of charging, constant voltage charging at 4.2V for another 2.5 hours),
Perform initial charge / discharge.

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. Discharge at constant current,
Measure the drop in battery voltage after 2 seconds in each condition discharge, and calculate the current value I that can flow for 2 seconds when the upper limit of charge voltage is 3 V from those measured values. The value calculated by the formula (W) is defined as the low temperature output characteristic of each battery.

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

A non-aqueous electrolyte secondary battery that has not undergone a charge / discharge cycle, a voltage range of 4.1 V at 25 ° C.
~ 3.0V, current value 0.2C (the rated capacity due to discharge capacity at 1 hour rate is 1C, the current value for discharging in 1 hour is 1C, the same shall apply hereinafter), 3 cycles, voltage range 4.2V-3.0V , Current value 0
. 2 cycles at 2C (at the time of charging, constant voltage charging at 4.2V for another 2.5 hours),
Perform initial charge / discharge.

Furthermore, after charging at a current value of 0.2 C to SOC 80%, storage processing is 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 Discharge capacity after being performed (in the voltage range 4.1V to 3.0V, 3 cycles, voltage range 4.
The ratio of the discharge capacity after storage to the discharge capacity after 2 cycles at 2 V to 3.0 V and a current value of 0.2 C is expressed as% 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 grinding, d50 = 8.9 μm, d (002) = 3.36 Å, (Raman R value) = 0.2
2. Natural graphite (A1) having (tap density) = 0.49 g / cm ³ is obtained. 100 g of the obtained natural graphite (A1) is stirred and mixed in the presence of 12 g of the granulating agent to obtain natural graphite with the granulating agent uniformly attached. The obtained natural graphite (B1) uniformly impregnated with the granulating agent is put into a hybridization system NHS-1 type manufactured by Nara Machinery Co., Ltd., and 1 at a rotor peripheral speed of 85 m / sec.
Spherical natural graphite (C1) obtained by spheroidizing by mechanical action for 0 minutes and pitch as a graphite precursor are mixed, heat treated at 1000 ° C. in an inert gas, and then 3000
Graphitizes at 0 ° C. to obtain a fired product. The fired product is crushed and classified to obtain a negative electrode material in which graphite and a graphite material are combined. From the firing yield, it is confirmed that in the obtained negative electrode material, the mass ratio of graphite to graphite (graphite: graphite) is 1: 0.2.

The pellet density, Raman R value, d50, BET-S of the sample obtained by the measurement method
Measure A, tap density, low temperature output characteristics and high temperature storage characteristics.

The negative electrode material for non-aqueous electrolyte secondary battery of the present invention, and the negative electrode for non-aqueous secondary battery and the non-aqueous secondary battery including the same are excellent in low-temperature output characteristics and high-temperature storage characteristics. It can be suitably used for mobile devices such as mobile phones and personal computers.

Claims (11)

It is spheroidized graphite in which a graphite material is compounded, and the pellet density is 1.10 to 1.60 g /
A negative electrode material for a non-aqueous secondary battery that is cc or less. The negative electrode material for a non-aqueous secondary battery according to claim 1, wherein the relationship between the pellet density and the volume-based average particle diameter (d50) satisfies the following formula (1).
Formula (1)
[Pellet density (g / cc)] ≦ 0.0138 × [d50 (μm)] + 1.42 The negative electrode material for nonaqueous secondary batteries according to claim 1 or 2, wherein the volume-based average particle diameter (d50) is 4 to 30 µm. The negative electrode material for nonaqueous secondary batteries according to any one of claims 1 to 3, wherein the Raman R value is 0.25 or less. The negative electrode material for a non-aqueous secondary battery according to any one of claims 1 to 4, wherein at least a part of the spheroidized graphite is coated with a graphite material. The negative electrode material for a non-aqueous secondary battery according to claim 1, wherein the spheroidized graphite includes natural graphite. 7. The non-aqueous secondary battery according to claim 1, wherein [tap density (g / cc)] / [specific surface area (m ² / g)] is 0.25 to 1.25. Negative electrode material. The negative electrode material for nonaqueous secondary batteries according to any one of claims 1 to 7, wherein the tap density is 0.80 to 1.50 g / cc. The negative electrode material for a nonaqueous secondary battery according to any one of claims 1 to 8, wherein the specific surface area is 1.00 to 12.0 m ² / g. A non-aqueous secondary battery negative electrode comprising a current collector and an active material layer formed on the current collector, wherein the active material layer is a non-active material according to any one of claims 1 to 9. A negative electrode for a non-aqueous secondary battery, comprising a negative electrode material for an aqueous secondary battery. A non-aqueous secondary battery comprising a positive electrode, a negative electrode, and an electrolyte, wherein the negative electrode is the negative electrode for a non-aqueous secondary battery according to claim 10.