KR102061629B1 - Multilayer-structure carbon material for nonaqueous secondary batteries, negative electrode for nonaqueous secondary batteries using same, and nonaqueous secondary battery - Google Patents

Abstract

A multilayer structure carbon material for a non-aqueous secondary battery, wherein at least a part of the surface of the graphite particles is coated with a carbonaceous material, and satisfies the following conditions (1) to (3):
(1) The average particle diameter d50 of the said multilayer structure carbon material is 19.1 micrometers or more and 50 micrometers or less
(2) The circularity of the said multilayer structure carbon material is 0.88 or more
(3) The ratio (P / d50) of the rolling load P defined below and d50 of the multilayer structure carbonaceous material is 30 or less:
P = (linear pressure (kg / 5cm) required for rolling the negative electrode active material layer under specific conditions using the multilayer structure carbonaceous material).

Description

MULTILAYER-STRUCTURE CARBON MATERIAL FOR NONAQUEOUS SECONDARY BATTERIES, NEGATIVE ELECTRODE FOR NONAQUEOUS SECONDARY BATTERIES USING SAME, AND NONAQUEOUS SECOND

The present invention relates to a multilayer structure carbon material for use in a nonaqueous secondary battery, a negative electrode for a nonaqueous secondary battery formed using the material, and a nonaqueous secondary battery having the negative electrode.

In recent years, with the miniaturization of electronic devices, the demand for a high capacity secondary battery is increasing. In particular, attention has been paid to non-aqueous secondary batteries having a higher energy density and excellent high-current charge / discharge characteristics than nickel-cadmium batteries or nickel-hydrogen batteries.

As a negative electrode material of a non-aqueous secondary battery, graphite material and amorphous carbon are often used in view of cost and durability. In addition, when charging and discharging are repeated on the metal electrode, the metal in the electrode solvent precipitates in the dendrite phase and finally shorts the positive electrode and the negative electrode, and also has excellent discharge capacity, charge and discharge efficiency, and rapid charge. Various studies have been made to achieve discharge characteristics and the like.

For example, Patent Document 1 discloses a method for producing carbon materials for electrodes of lithium batteries having high discharge capacity and charge / discharge efficiency, and firing the mesophase globules while raising the temperature at a temperature increase rate of 40 ° C / hour or less, quinoline Carbonizing mesophase globules that satisfies at least one of at least 89.5% by weight of insoluble content and at least 93.6% by weight of toluene insoluble content, or by grinding the mesoface globules to obtain a granule having a particle size d50 of 1.3 to 15 µm. Manufacture of carbon materials for electrodes comprising carbonizing at a temperature of ˜1500 ° C. or carbonizing mesophase globules at a temperature of 600 to 1500 ° C. and pulverizing them to a granule having an average particle diameter d50 of 1.8 to 15 μm. A method is disclosed.

In addition, Patent Document 2 discloses a method of using spheroidized graphite and carbonaceous particles obtained by treating a graphite material having a high capacity, but hardly obtainable, in a sphere in order to obtain rapid charge and discharge characteristics and a high capacity, and the obtained sphere. Disclosed is a multilayer structure carbon material obtained by carbonizing an organic compound after mixing the graphite with an organic compound.

In addition, Patent Document 3 has an extremely small amount such that the carbonaceous material is 12 parts by weight or less and 0.1 parts by weight or more in terms of the residual carbon content of 100 parts by weight of the graphite carbonaceous material on the surface of the graphite carbonaceous material. Disclosed is an electrode material formed by the attachment of carbides (low concentrations) of organic material, which provides very good electrical properties with high electrical capacity and low retention compared to graphite alone or a conventional clear multilayer structure carbon material. Furthermore, the content of the purpose of obtaining a nonaqueous solvent secondary battery with high stability with respect to electrolyte solution is described.

Patent Literature 4 discloses lithium ions that achieve good discharge capacity, initial charge and discharge efficiency, rate characteristics, and cycle characteristics by setting the pore volume of the graphite core material, the d ₀₀₂ , R value of the negative electrode material, and the peak intensity ratio of the Raman spectrum to a certain range. A negative electrode material for a secondary battery is described. In the example of this document, the average particle diameter of the graphitized material used as a graphite core material is 10 micrometers.

Patent Literature 5 describes a lithium ion battery having an electrolyte solution containing at least an ionic liquid and a lithium salt composed of a bis (fluorosulfonyl) imide anion, a positive electrode and a negative electrode, and the negative electrode active material covers amorphous carbon on the surface of the graphite particles. Or it described that the irreversible capacity was reduced and the capacity was improved by the lithium ion battery characterized by the adhesion. In this document, the particle size of the graphite particles is not considered.

Patent Literature 6 describes using graphite particles coated with amorphous carbon as a negative electrode active material and achieving excellent potential flatness, low temperature characteristics, and capacity by a non-aqueous secondary battery using an organic electrolyte solution having a specific composition. In Examples of this document, graphite particles having a particle diameter of about 13 to 18 µm are used as raw materials for the negative electrode active material.

Patent Document 7 has a graphite material for lithium ion secondary battery, characterized in that a coating layer made of carbide is formed on the surface of the pressurized graphite particles to which the natural graphite spheroidized particles and / or the natural graphite agglomerated particles are pressurized. It is described that the excellent electrode density, initial efficiency, and load characteristic were achieved by the following. In this invention, although the average particle diameter of graphite material is prescribed | regulated to 5-50 micrometers, what is actually used in the Example is up to 13 micrometers.

Patent Document 8 discloses excellent rapid charging and discharging using a negative electrode material containing two kinds of carbon materials having a constant surface spacing, tap density, peak intensity ratio in the Raman spectrum, and the like on the 002 plane by X-ray wide-angle diffraction. It is described that the characteristics and cycle characteristics have been achieved. Although the average particle diameter of the two types of carbon materials which comprise this negative electrode material is prescribed | regulated to 2-30 micrometers, the average particle diameter of the said carbon material actually manufactured in the Example is 11.6-13.4 micrometers.

Patent Document 9 has an average particle diameter of 10 to 30 µm, and the decomposition of the electrolyte solution is suppressed by the low crystalline carbon coated graphite prepared so that the specific surface area before and after the formation of the low crystalline carbon coating layer is reduced to a specific ratio range, and thus the charge and discharge efficiency is reduced. And improved cycle life. In addition, in Examples of this document, a carbon material of various conditions in which the average particle diameter is 10 to 30 µm and the graphite powder is coated using a pitch of 2.0 to 4.5% by mass has been studied, but the ratio before forming the low crystalline carbon coating layer When a large particle size (average particle diameter> 19 micrometer) with a small surface area is used, pitch amount is set comparatively high at 4.5 mass% in order to make the specific surface area before and after formation of a low crystalline carbon coating layer in a specific range.

Patent Document 10 discloses excellent discharge characteristics and cycle life characteristics by a nonaqueous electrolyte secondary battery using a graphite powder having a ratio of average thickness and average diameter, a ratio of d10 and d90, and a volume content of 4 μm or less particles of 4% or less. What is achieved is described. In the claims of this document, the average particle diameter of the graphite powder is defined to be 10 to 35 m, and in the examples, the carbon powder is coated with 5% by weight of petroleum tar pitch.

Patent Literature 11 describes that excellent capacity density and input / output characteristics are achieved by graphite coated with a low crystalline carbon material and a negative electrode carbon material for lithium secondary battery composed of a specific carbon material. In the examples of this document, the graphite has a D50 of 21.5 μm, but the carbon material has a D50 of 10.5 μm.

Patent Literature 12 includes (b) an argon ion laser light having a volume average particle diameter of 2 to 70 µm, a tap density of 0.80 g / cm ³ or more, an average circularity of 0.94 or more, and a wavelength of 514.5 nm. argon ion laser Raman is suppressed, the press force by the multilayer structure carbonaceous material greater than the ratio R value of scattering intensity of 1360cm ^-1 is 0.15 for the scattering intensity of 1580cm ^-1 in the spectra with low, resulting in high discharge capacity and It is described that the irreversible capacity during initial charge and discharge can be lowered. The volume average particle diameter of the multilayer structure carbonaceous material prepared in the examples of this document is 16.4 to 16.8 mu m.

Patent Document 13 discloses that the graphite-based material, which is a core material, is immersed in an organic compound at 10 to 300 ° C, the immersed graphite-based material is separated, and an organic solvent is added to the separated graphite-based material and 10 to 300 ° C. Characterized by adjusting the particle size by pulverizing and classifying the carbon material whose surrounding surface of the carbon particles obtained by carbonization after washing with carbon or an aggregate of carbon particles is covered with low crystalline carbon. It is described by the manufacturing method of the carbon material to provide the highly stable lithium secondary battery excellent in the charge / discharge characteristic. The thickness of the said low crystalline carbon becomes about 0.01-0.1 micrometer, and the carbon material whose number average particle diameter is 10 micrometer is manufactured in the Example.

Patent document 14 discloses a negative electrode material having an average particle diameter of 100 μm or less in which a coating layer of crystalline carbon is formed on the surface of graphite particles, and the graphite particles have a laminated structure in which the graphite particles are folded therein. This discloses that it is possible to manufacture a lithium secondary battery having a high energy density. In the examples of this document, spheroidized graphite particles having an average particle diameter of 25.4 µm are used, and 3 to 14% of carbon coating is applied thereto.

Patent Document 15 achieves excellent charge and discharge characteristics and cycle characteristics by a nonaqueous electrolyte secondary battery comprising a composite carbon material covering the surface of carbonaceous particles with amorphous carbon and containing a specific amount of a specific compound as a nonaqueous electrolyte solvent. One is described. In Examples of this document, flaky natural graphite having an average particle diameter of 20 µm is used as the carbonaceous particles.

Japanese Patent No. 3634408 Japanese Patent No. 3916012 Japanese Patent No. 3712288 Japanese Patent Application Laid-Open No. 2011-243567 Japanese Patent Application Laid-Open No. 2010-97696 Japanese Patent Laid-Open No. 9-237638 Japanese Patent Application Laid-Open No. 2011-60465 Japanese Patent Application Laid-Open No. 2010-251315 International Publication No. 2008/093724 Japanese Patent Application Laid-Open No. 2000-90930 Japanese Laid-Open Patent Publication No. 2009-117240 Japanese Patent Laid-Open No. 2009-209035 Japanese Patent Laid-Open No. 10-36108 Japanese Patent Application Laid-Open No. 2002-367611 Japanese Patent Laid-Open No. 2004-265754

By the way, when the negative electrode for a non-aqueous secondary battery is constituted by the powder of the carbonaceous material for graphite non-aqueous secondary batteries, a slurry is prepared by mixing the powder and the binder, adding a dispersion medium thereto, and applying the slurry to the metal foil as the current collector. Then, the method of drying a dispersion medium is generally used.

Under the present circumstances, it is common to provide the process of rolling further for the purpose of the crimping | compression-bonding with respect to an electrical power collector of powder, the uniformity of the pole plate thickness of an electrode, and the improvement of a pole plate capacity. By this rolling process, the electrode plate density of a negative electrode improves, and the energy density per volume of a battery improves further.

In view of the uniformity of the electrode plate thickness, it is considered that it is advantageous to reduce the particle size of the carbonaceous material for the graphite-based non-aqueous secondary battery to some extent. In the invention disclosed in Patent Document 1, the particle size of the electrode carbonaceous material is 15 µm or less. It is.

In addition, in the documents of Patent Documents 4, 6, 7, 8, 12, and 13, the particle diameters of those actually produced at the Example level are up to about 18 µm.

In addition, in order to increase the electrode plate density, the pressure of rolling increases. However, in the conventional carbonaceous non-aqueous secondary battery carbon material, when rolling at a pressure sufficient to achieve a high capacity, the carbon material is damaged and material destruction occurs, thereby increasing the charge and discharge irreversible capacity during the initial cycle, resulting in higher capacity. There is a problem that can not be achieved.

The present invention solves this problem and provides a carbon material for a non-aqueous secondary battery that can achieve a high capacity even by rolling at a pressure such that material destruction does not occur and charge / discharge irreversible capacity is suppressed small. The purpose.

MEANS TO SOLVE THE PROBLEM As a result of earnestly examining in order to solve the said subject, as a negative electrode material, the multilayer structure carbon material manufactured by coat | covering at least one part of the spherical graphite particle surface of unexpectedly large average particle diameter thinner than before is used as a negative electrode material. By discovering that the electrode for non-aqueous secondary batteries with sufficient capacity | capacitance can be obtained even by rolling in the pressure which does not cause material destruction, it came to this invention.

In the conventional technique for spheroidizing graphite particles, it has been difficult to produce spherical graphite particles having a large average particle diameter when treated so as to be spherical. However, recent advances in the spheronization treatment technology have made it possible to achieve a large average particle diameter and a high circularity at the same time.

When the electrode is manufactured using a carbon material obtained by coating a graphite having a small particle diameter with a conventional carbonaceous material, a pressure corresponding to the electrode press is required, and thus, material destruction occurs as described above, and side reaction with the electrolyte is increased. . In addition, since there are few voids in the particles and a smallly divided structure, the carbon material is hard and difficult to deform, so that the contact between the particles of the carbon material is small (point contact) at the electrode, and the adhesion between the particles is also high. This weak electrode strength is low.

On the other hand, according to this invention, since the large particle sized graphite particle is coat | covered with a small amount of carbonaceous substance compared with the past, the obtained carbon material particle forms an electrode smoothly, and does not need a strong press. Therefore, material destruction of the carbon material is unlikely to occur during the production of the electrode, and the carbon material tends to be deformed smoothly, and the contact between particles is large (interview point) in the electrode, and the adhesion between the particles is high.

That is, the gist of the present invention is as follows.

[1] A multilayer structure carbon material for a non-aqueous secondary battery, wherein at least a part of the surface of the graphite particles is coated with a carbonaceous material, and satisfies the following conditions (1) to (3):

(1) The average particle diameter d50 of the said multilayer structure carbon material is 19.1 micrometers or more and 50 micrometers or less.

(2) The circularity of the said multilayer structure carbon material is 0.88 or more.

(3) The ratio (P / d50) of the rolling load P defined below and d50 of the multilayer structure carbonaceous material is 30 or less:

P = (Current collector using a multilayer structure carbon material, comprising a 1% by mass of carboxymethyl cellulose sodium salt and 1% by mass of styrene-butadiene rubber as a binder relative to the multilayer structure carbon material Linear pressure (kg / 5cm) required to prepare a negative electrode active material layer deposited in an amount of 12.0 mg / cm ² above, and to roll the density of the negative electrode active material layer to 1.6 g / cm ³ ).

[2] The multilayer structure carbon material for nonaqueous secondary batteries according to [1], wherein the tap density of the multilayer structure carbon material for nonaqueous secondary batteries is 0.8 g / cm ³ or more and 1.30 g / cm ³ or less.

[3] The nonaqueous secondary according to the above [1] or [2], wherein the specific surface area of the multilayer structure carbonaceous material for a non-aqueous secondary battery is 0.2 m ² / g or more and 4.5 m ² / g or less measured by the BET method. Multi-layered carbon material for batteries.

[4] The multilayer structure carbon material for non-aqueous secondary batteries according to any one of [1] to [3], wherein the Raman R value of the graphite particles is 0.1 or more and 0.6 or less.

[5] A multilayer structure carbon material for a non-aqueous secondary battery, wherein at least a part of the surface of the graphite particles is coated with a carbonaceous material, and satisfies the following conditions (1) to (3):

(1) The average particle diameter d50 of the said multilayer structure carbon material is 19.1 micrometers or more and 50 micrometers or less

(2) The circularity of the said multilayer structure carbon material is 0.88 or more

(3) 0.01 mass% or more and 2.7 mass% or less of the adhesion amount of the said carbonaceous substance in the said multilayer structure carbon material.

[6] An anode for a non-aqueous secondary battery comprising a current collector and a multilayer structure carbon material layer formed on the current collector, wherein the multilayer structure carbon material layer is the nonaqueous system according to any one of the above [1] to [5]. The negative electrode for non-aqueous secondary batteries containing the multilayer structure carbon material for secondary batteries.

[7] A nonaqueous secondary battery comprising a positive electrode capable of occluding and releasing lithium ions, a negative electrode, and a nonaqueous electrolyte, wherein the negative electrode is a negative electrode for a nonaqueous secondary battery according to the above [6].

In the nonaqueous secondary battery using the negative electrode for a nonaqueous secondary battery obtained in the present invention, material destruction of the negative electrode material at the negative electrode is extremely unlikely, and side reactions with the electrolyte are reduced, thereby improving initial efficiency and The irreversible capacity is also small and high capacity can be achieved. In addition, since the multilayer structure carbon material for a non-aqueous secondary battery of the present invention to be the negative electrode is soft, the adhesion between the carbon material particles in the negative electrode is strong, and excellent negative electrode strength is achieved.

EMBODIMENT OF THE INVENTION Hereinafter, the content of this invention is demonstrated in detail. In addition, description of the invention structural requirements described below is an example (representative example) of the embodiment of this invention, and this invention is not specified in these forms unless the summary is exceeded.

In addition, in this specification, "mass%", "weight%", "mass ppm", "weight ppm", and "mass part" and "weight part" are the same meaning, respectively. In addition, when simply described as "ppm", it refers to "weight ppm".

[Multilayered Carbon Material for Non-aqueous Secondary Battery]

The multilayer structure carbon material (hereinafter, also simply referred to as "the multilayer structure carbon material of the present invention") for a non-aqueous secondary battery of the present invention is formed by coating at least a part of the surface of the graphite particles with a carbonaceous material, It is characterized by satisfy | filling all 1)-(3). In addition, the multilayer referred to in this specification means the aspect in which at least one part or whole surface of graphite particle (nuclear graphite) surface is coat | covered or impregnated with a carbonaceous substance. This aspect can be confirmed by a physical property, SEM photograph, etc. which are shown below.

(1) The average particle diameter d50 of a multilayer structure carbon material should be 19.1 micrometers or more and 50 micrometers or less

(2) The circularity of this multi-layered carbon material is not less than 0.88

(3) The ratio (P / d50) of the rolling load (P) and d50 of this multilayer structure carbon material defined below shall be 30 or less:

P = (Current collector using a multilayer structure carbon material, comprising a 1% by mass of carboxymethyl cellulose sodium salt and 1% by mass of styrene-butadiene rubber as a binder relative to the multilayer structure carbon material Linear pressure (kg / 5cm) required to prepare a negative electrode active material layer deposited in an amount of 12.0 mg / cm ² above, and to roll the density of the negative electrode active material layer to 1.6 g / cm ³ )

Hereinafter, the conditions which satisfy | fill these conditions and the multilayered structure carbon material of this invention are demonstrated in order. In addition, in this invention, the multilayer structure carbon material which satisfy | fills the said conditions (1)-(3) may be used individually by 1 type, and may be used in combination of other carbon materials.

(1) Volume-based average particle diameter (average particle diameter d50)

The volume-based average particle diameter (also referred to as "average particle diameter d50") of the multilayer structure carbonaceous material of the present invention is 19.1 µm or more, preferably 20.1 µm or more, more preferably 22 µm or more, particularly preferably 24 µm or more Moreover, average particle diameter d50 is 50 micrometers or less, More preferably, it is 40 micrometers or less, More preferably, it is 35 micrometers or less, Especially preferably, it is 31 micrometers or less. When the average particle diameter d50 is too small, the packing property at the time of compression molding of particle | grains will fall, and there exists a tendency for rolling load P to increase. In addition, there is a tendency that the irreversible capacity of the non-aqueous secondary battery obtained by using the carbon material is increased, and the initial battery capacity is lost. On the other hand, when the average particle diameter d50 is too large, process inconvenience such as streaking in slurry coating is applied. There is a possibility of causing occurrence, deterioration of high current density charge and discharge characteristics, and deterioration of low temperature input / output characteristics.

In addition, in this specification, the average particle diameter d50 is obtained by suspending 0.01 g of a multilayer structure carbon material in 10 mL of a 0.2 mass% aqueous solution of a polyoxyethylene sorbitan monolaurate (for example, Tween 20 (registered trademark)) which is a surfactant. The sample was introduced into a commercially available laser diffraction / scattering particle size distribution measuring device (e.g., LA-920 manufactured by HORIBA) and irradiated with 28 kHz ultrasonic waves at an output of 60 W for 1 minute. It is defined as measured by the median diameter on the basis of volume in the measuring device.

(2) roundness

The circularity of the multilayer structure carbon material of this invention is 0.88 or more, Preferably it is 0.90 or more, More preferably, it is 0.91 or more. The circularity is usually 1 or less, preferably 0.98 or less, and more preferably 0.97 or less. If the circularity is too small, the high current density charge / discharge characteristics of the non-aqueous secondary battery tend to be lowered. In addition, circularity is defined by the following formula, and when circularity is 1, it becomes a theoretically perfect sphere.

Circularity = (perimeter length of equivalent circle with the same area as the particle projection shape) / (actual perimeter length of the particle projection shape)

As the circularity value, for example, polyoxyethylene (20) containing about 0.2 g of a sample (multi-layered carbon material) as a surfactant using a flow particulate analysis device (e.g., Sysmex Industrial Co., Ltd.). After dispersing in 0.2 mass% aqueous solution of sorbitan monolaurate (about 50 mL), irradiating the dispersion liquid with an ultrasonic wave of 28 kHz for 1 minute at an output of 60 W, the detection range was specified as 0.6 to 400 μm, and the particle size was in the range of 1.5 to 40 μm. The value measured about the particle | grain of is used.

Although the method of improving circularity is not specifically limited, It is preferable because the shape of the interparticle space | gap at the time of making it the cathode by performing sphericalization process and making it spherical is preferable. Examples of spheronization treatment include mechanically and physically treating a method of making the particles close to a spherical shape by applying a shear force and a compressive force, and granulating a plurality of multilayer structure carbonaceous particles with an adhesive force possessed by a binder or the particles themselves. Can be mentioned.

In the conventional spheronization treatment technology, when the high circularity as described above is achieved, the average particle diameter of the carbon material is reduced, but the recent technological advances have made both the high circularity and the large average particle diameter compatible. .

(3) Ratio of rolling load (P) and d50 of multilayer structure carbon material

In the multilayer structure carbonaceous material of the present invention, a negative electrode active material containing 1% by mass of carboxymethyl cellulose sodium salt and 1% by mass of styrene-butadiene rubber as a binder in an amount of 12.0 mg / cm ² on the current collector. The ratio of the rolling load (P), which is the linear pressure (kg / 5cm), required for rolling the negative electrode active material layer attached thereto and rolling the density of the negative electrode active material layer to 1.6 g / cm ³ and the average particle diameter d50 of the multilayer structure carbon material ( P / d50) is 30 or less, Preferably it is 3-25, More preferably, it is 4-22.

Particles of the multilayer structure carbon material of the present invention can be made softer than the conventional carbon material particles by lowering the amount of carbonaceous substance to be attached to a specific range or less, so that the rolling load P can be made smaller even with the same d50. The ratio of P / d50 is smaller than that of the material. In addition, this ratio is about 3 substantially lower limit at the time of negative electrode manufacture.

The multilayer structure carbonaceous material for a non-aqueous secondary battery of the present invention can exhibit the above-described effects of the present invention and exhibit sufficient performance when the above requirements are satisfied, but any one of the conditions (4) to (16) described below or It is preferable to satisfy a plurality simultaneously. It is especially preferable to satisfy the following conditions (4).

(4) deposition amount of carbonaceous material

The carbonaceous substance adhering amount in the multilayer structure carbon material of this invention shows the coating amount of the carbonaceous substance with respect to graphite particle, In this invention, Preferably it is 0.01-2.7 mass%, More preferably, it is 0.1 mass%. More than 0.3 mass% or more, Especially preferably, it is 0.7 mass% or more, and the said amount of adhesion is preferably 2.5 mass% or less, More preferably, 2.3 mass% or less, More preferably, 2.1 mass% Hereinafter, Especially preferably, it is 1.8 mass% or less, Most preferably, it is 1.3 mass% or less.

If the amount of adhesion exceeds 2.7% by mass, the carbon material is damaged when rolling at a sufficient pressure to achieve a high capacity in the non-aqueous secondary battery, resulting in material destruction, resulting in an increase in the charge / discharge irreversible capacity during the initial cycle and a decrease in initial efficiency. Tends to result.

On the other hand, when the amount of deposition is less than 0.01% by mass, the effect of forming a multilayer tends to be difficult to be obtained. That is, there is a tendency that the side reaction with the electrolyte solution cannot be sufficiently suppressed in the battery, resulting in an increase in the charge / discharge irreversible capacity during the initial cycle and a decrease in the initial efficiency. Although the layer of carbonaceous material is thin and uniformly present over most of the surface of the graphite particles, the effect of the present invention can be exhibited, but the amount of carbonaceous material is so small that the graphite particles themselves form the multilayer structure of the present invention. If it appears a lot on the outermost surface of the material it is difficult to obtain the effect of the present invention.

The amount of deposition of the carbonaceous substance in the present invention can be calculated from the sample mass before and after material firing (as described below, the multilayer structure carbonaceous material of the present invention is mixed with graphite particles and a carbon precursor, such as firing). Obtained by heat treatment). In addition, it is calculated at this time that there is no mass change before and after baking of graphite particle.

When w1 is the mass of graphite particles before firing (kg) and w2 is the mass of the multilayer structure carbon material particles after firing (kg),

Amount of adhesion (mass%) of the carbonaceous substance = [(w2-w1) / w2] x 100

Is calculated.

(5) tap density

The tab density of the multilayer structure carbon material of the present invention is 0.8 g / cm ³ or more and 1.30 g / cm ³ or less, preferably 0.90 g / cm ³ or more and 1.20 g / cm ³ or less, and more preferably 0.95 g / cm ^{It is 3} or more and 1.10 g / cm <^3> or less.

When the tap density is less than 0.8 g / cm ³ , the negative electrode forming material slurry is streaked in the case of polarization, and there is a tendency to become a process problem. On the other hand, when the tap density exceeds 1.30 g / cm ³ , the carbon density in the particles of the multilayer structure carbon material rises, resulting in poor rollability, making it difficult to form a high-density negative electrode sheet.

The tap density is filled by filling the cell by filling the multilayer structure carbon material of the present invention through a sieve of 300 µm into a cylindrical tapping cell having a diameter of 1.6 cm and a volume capacity of 20 cm ³ using a powder density meter. After that, tapping with a stroke length of 10 mm is performed 1000 times to define the density obtained from the volume at that time and the mass of the sample.

(6) X-ray parameter

The d-value (interlayer distance) of the lattice plane (002 plane) of the multilayer structure carbon material of this invention calculated | required by the X-ray diffraction by the school-based method is 0.337 nm or less normally. Too large a d002 value indicates low crystallinity, and the initial irreversible capacity may increase when a nonaqueous secondary battery is used. On the other hand, since the theoretical value of the surface spacing of the 002 plane of graphite is 0.335 nm, the said d value is 0.335 nm or more normally.

In addition, the crystallite size (Lc) of the multilayer structure carbon material determined by X-ray diffraction by the Hakjin method is usually 1.5 nm or more, preferably 3.0 nm or more. If it exceeds this range, it becomes a particle with low crystallinity, and when a nonaqueous secondary battery is used, the reversible capacity may fall. In addition, the minimum of Lc is a theoretical value of graphite.

(7) ash

It is preferable that it is 1 mass% or less normally and 0.5 mass% or less with respect to the total mass of a multilayer structure carbon material, and, as for the ash contained in the multilayer structure carbon material of this invention, it is more preferable that it is 0.1 mass% or less. Moreover, it is preferable that the lower limit of ash content is 1 ppm or more.

When ash exceeds the said range, when a non-aqueous secondary battery is used, deterioration of battery performance by reaction of the multilayer structure carbon material and electrolyte solution at the time of charge and discharge may become insignificant. On the other hand, if it is less than the above range, the cost of the carbon material may require a lot of time, energy, and equipment for preventing pollution, thereby increasing the cost.

(8) BET specific surface area

The specific surface area SA measured by the BET method of the multilayer structure carbon material of the present invention is usually 0.2 m ² / g or more, preferably 0.3 m ² / g or more, more preferably 0.7 m ² / g or more, further It is preferably at least 1 m ² / g, particularly preferably at least ² m ² / g. In addition, the specific surface area is usually 100 m ² / g or less, preferably 10 m ² / g or less, more preferably 7 m ² / g or less, still more preferably 4.5 m ² / g or less, particularly preferably 4.0 m ² / g or less, most preferably 3.6 m ² / g or less.

If the specific surface area value is too small, the reaction area in the case of forming a negative electrode using a multilayer structure carbon material is particularly reduced, and a long time until full charge is required, which tends to make it difficult to obtain a desirable non-aqueous secondary battery. .

On the other hand, when the specific surface area value is too large, the reactivity with the electrolytic solution in the case of forming a negative electrode using a multilayer structure carbon material tends to increase the gas generation easily, and it is difficult to obtain a preferable non-aqueous secondary battery.

The BET specific surface area was preliminarily dried at 350 ° C. for 15 minutes under nitrogen flow to a multi-layered carbonaceous material sample using a surface area meter (e.g., a fully automatic surface area measuring instrument manufactured by Okurariken), and then the relative pressure of nitrogen to atmospheric pressure. It defines by the value measured by the nitrogen adsorption BET 1 point method by the gas flow method using the nitrogen helium mixed gas correctly adjusted so that the value of pressure might be 0.3.

(9) pore distribution

In the multilayer structure carbonaceous material of the present invention, the amount of irregularities in the grains and steps of the surface of the particles corresponding to 0.01 µm or more and 1 µm or less, which is determined by mercury porosimetry (mercury porosimetry), is usually 0.01 mL / g or more, preferably 0.05 mL / g or more, more preferably 0.1 mL / g or more. The amount is usually 0.6 mL / g or less, preferably 0.4 mL / g or less, and more preferably 0.3 mL / g or less.

If the amount of unevenness is too large, a large amount of binder may be required at the time of polarization when forming a negative electrode. On the other hand, if the amount of unevenness is too small, the high current density charge / discharge characteristics of the non-aqueous secondary battery not only decrease, but also tend to be unable to obtain the effect of reducing the expansion and contraction of the electrode during charge and discharge.

Moreover, the total pore volume of the multilayer structure carbon material of this invention is 0.1 mL / g or more normally, Preferably it is 0.2 mL / g or more, More preferably, it is 0.25 mL / g or more. The total pore volume is usually 10 mL / g or less, preferably 5 mL / g or less, and more preferably 2 mL / g or less.

If the total pore volume is too large, a large amount of binder tends to be necessary at the time of polarization. On the other hand, when the total pore volume is too small, there is a tendency that the effect of dispersing a thickener or a binder is not obtained at the time of pole-printing.

Moreover, the average pore diameter of the multilayer structure carbon material of this invention is 0.03 micrometer or more normally, Preferably it is 0.05 micrometer or more, More preferably, it is 0.1 micrometer or more, More preferably, it is 0.5 micrometer or more. The said average pore diameter is 80 micrometers or less normally, Preferably it is 50 micrometers or less, More preferably, it is 20 micrometers or less.

If the average pore diameter is too large, a large amount of binder tends to be required during polarization, and if the average pore diameter is too small, the high current density charge / discharge characteristics of the battery tend to be lowered.

As a device for mercury porosimetry, a mercury porosimeter (Autopore 9520: manufactured by Micromeritex) can be used. The sample (multilayer structure carbon material) is weighed to a value of about 0.2 g, encapsulated in a powder cell, degassed at room temperature and under vacuum (50 µm Hg or less) for 10 minutes, and pretreated.

Subsequently, the pressure was reduced to 4 psia (about 28 kPa) and mercury was introduced into the cell to increase the pressure from 4 psia (about 28 kPa) to 40000 psia (about 280 MPa) on a step, and then down to 25 psia (about 170 kPa).

The step number at the time of pressurization shall be 80 or more points, and the mercury intrusion amount is measured after a 10 second equilibrium time in each step. The pore distribution is calculated from the mercury intrusion curve thus obtained using the Washburn equation.

In addition, the surface tension (gamma) of mercury is calculated as 485 dyne / cm, and the contact angle (psi) is 140 degreeC. The average pore diameter is defined as the pore diameter when the cumulative pore volume becomes 50%.

(10) true density

A multi-layer structure the true density of the carbonaceous material of the present invention is usually 1.9g / cm ³ or more, preferably 2g / cm ³ or more, more preferably 2.1g / cm ³ or more, more preferably 2.2g / cm ³ or more , The upper limit is 2.26 g / cm ³ . The upper limit is a theoretical value of graphite. If it is less than this range, the initial irreversible capacity may increase when the crystallinity of carbon is too low and a nonaqueous secondary battery is used.

(11) aspect ratio

The aspect ratio in the powder state of the multilayer structure carbon material of this invention is 1 or more in theory, Preferably it is 1.1 or more, More preferably, it is 1.2 or more. The aspect ratio is usually 10 or less, preferably 8 or less, and more preferably 5 or less.

If the aspect ratio is too large, streak dragging of the slurry (cathode forming material) containing the multilayer structure carbon material at the time of polarization occurs, or a uniform coating surface is not obtained, resulting in high current density charge / discharge characteristics of the non-aqueous secondary battery. It tends to be lowered.

The aspect ratio is represented by A / B when the diameter A becomes the longest diameter A of the multilayer structure carbon material particles in the three-dimensional observation and the diameter B orthogonal thereto. Observation of the carbon material particles is performed with a scanning electron microscope that can be enlarged and observed. 50 arbitrary carbon particle | grains fixed to the end surface of the metal of 50 micrometers or less in thickness are selected, and the stage to which the sample is fixed with respect to each is rotated and inclined, A and B are measured, and the average value of A / B is calculated | required.

(12) Maximum particle diameter dmax

The maximum particle diameter dmax of the multilayer structure carbon material of this invention is 200 micrometers or less normally, Preferably it is 150 micrometers or less, More preferably, it is 120 micrometers or less, More preferably, it is 100 micrometers or less, Especially preferably, it is 80 micrometers or less. Too large dmax tends to cause process inconvenience, such as streaking.

In addition, the maximum particle diameter is defined as the value of the largest particle diameter which particle | grains were measured in the particle size distribution obtained at the time of measuring the average particle diameter d50.

(13) Raman R value

The Raman R value of the multilayer structure carbon material of this invention is 0.1 or more normally, Preferably it is 0.2 or more. Moreover, Raman R value is 0.6 or less normally, Preferably it is 0.55 or less, More preferably, it is 0.5 or less.

In addition, the Raman R value is measured the intensity I _B of a peak P _B of the intensity I _A of a peak P _A in the vicinity of 1580cm ^-1 in a Raman spectrum obtained by Raman spectroscopy, near 1360cm ^-1, and the intensity ratio (I _B / I _A ) is defined as calculated.

Also, of the scope of it is called herein, "near 1580cm ^-1" 1580~1620cm ^-1, "the vicinity of 1360cm ^-1" refers to the range of 1350~1370cm ^-1.

If the Raman R value is too small, the crystals on the surface of the carbon material particles become too high, and when the density is increased, the crystals tend to be oriented in the parallel direction with the negative electrode plate, and the load characteristics tend to be lowered. On the other hand, when the Raman R value is too large, crystals on the surface of the particles become uneven and the reactivity with the electrolyte of the negative electrode increases, which tends to cause a decrease in the charge / discharge efficiency of the non-aqueous secondary battery and an increase in gas generation.

The Raman spectrum can be measured with a Raman spectrometer. Specifically, the particle to be measured is naturally dropped in the measurement cell, and the sample is filled. The measurement is performed while the measurement cell is rotated in a plane perpendicular to the laser light while irradiating argon ion laser light into the measurement cell. Measurement conditions are as follows.

Wave length of argon ion laser light: 514.5nm

Laser power on the sample: 25 mW

Resolution: 4cm ^-1

Measuring range: 1100cm ^-1 to 1730cm ^-1

Peak intensity measurement, peak half value width measurement: background processing, smoothing processing (5 points of convolution by simple average)

(14) DBP oil absorption

DBP (dibutyl phthalate) oil absorption amount of the multilayer structure carbon material of this invention is 65 ml / 100g or less normally, Preferably it is 62 ml / 100g or less, More preferably, it is 60 ml / 100g or less, More preferably, it is 57 ml / 100g or less. Moreover, DBP oil absorption amount is 30 ml / 100g or more normally, Preferably it is 40 ml / 100g or more.

If the DBP oil absorption is too large, the degree of progress of spheroidization of the multilayer structure carbon material is not sufficient, and there is a tendency to cause streaking and the like at the time of application of the slurry containing the carbon material. There is a possibility that it does not exist, so there is a tendency that the reaction surface is small.

In addition, DBP oil absorption amount is defined by the measured value at the time of making 40 g of measurement materials (multilayer structure carbon material) into a dropping rate 4 ml / min, rotation speed 125 rpm, and setting torque 500N * m based on JISK6217. As the measurement, for example, an Absorptometer E type manufactured by Brabender can be used.

(15) Average particle diameter d10

The particle size d10 corresponding to cumulative 10% from the small particle side of the particle size measured on the basis of the volume of the multilayer structure carbon material of the present invention is usually 30 μm or less, preferably 20 μm or less, more preferably 17 μm or less. It is 1 micrometer or more normally, Preferably it is 5 micrometers or more, More preferably, it is 10 micrometers or more, More preferably, it is 11 micrometers or more, Especially preferably, it is 13 micrometers or more.

When d10 is too small, the agglomeration tendency of the particles becomes strong, and there is a tendency to cause process inconvenience such as increase in slurry viscosity, decrease in electrode strength in the non-aqueous secondary battery, and decrease in initial charge and discharge efficiency. When d10 is too big | large, it exists in the tendency which leads to the fall of a high current density charge / discharge characteristic, and the fall of a low temperature input / output characteristic.

d10 is defined as the value which the frequency% of particle | grains became 10% by integration from the small particle diameter in the particle size distribution obtained at the time of measuring the average particle diameter d50.

(16) Average particle size d90

The particle size (d90) corresponding to a cumulative 90% from the small particle side of the particle size measured based on the volume of the multilayer structure carbon material of the present invention is usually 100 μm or less, preferably 70 μm or less, more preferably 60 μm or less. More preferably at most 50 μm, particularly preferably at most 45 μm, most preferably at most 42 μm, usually at least 20 μm, preferably at least 26 μm, more preferably at least 30 μm, still more preferably 34 It is more than micrometer.

Too small d90 may cause a decrease in electrode strength or a decrease in initial charge and discharge efficiency in a non-aqueous secondary battery, and too large d90 may cause process inconveniences such as streaking during slurry application and high current density charge and discharge. Deterioration of characteristics and deterioration of low-temperature input / output characteristics may be caused.

d90 is defined as the value by which the frequency% of particle | grains became 90% by integration from the small particle diameter in the particle size distribution obtained at the time of measuring the average particle diameter d50.

As mentioned above, it is preferable to satisfy the conditions (1), (2) and (3) described above, and to satisfy any one or more of the conditions (4) to (16) (particularly condition (4)) at the same time. . The multilayer structure carbon material of this invention which satisfy | fills these various conditions has graphite particle | grains and a carbonaceous material as a component. Hereinafter, these two components are demonstrated.

<Graphite Particles>

It is preferable that the graphite particle used as the nuclear graphite of the multilayer structure carbon material of this invention satisfy | fills any one or multiple of the following physical properties. In this invention, 1 type of graphite particles which show such a physical property may be used independently, and 2 or more types may be used together by arbitrary combinations.

(1) X-ray parameter

The graphitic particles usually have a d002 value (interlayer distance) of the lattice plane (002 plane) determined by X-ray diffraction by the Hakjin method in general at least 0.335 nm. Moreover, although it is less than 0.340 nm normally, Preferably it is 0.337 nm or less. If the d002 value is too large, the crystallinity decreases, and the initial irreversible capacity of the non-aqueous secondary battery tends to increase.

In addition, the crystallite size (Lc) of the graphite particles obtained by X-ray diffraction by the Hakjin method is usually in the range of 30 nm or more, preferably 50 nm or more, and more preferably 100 nm or more. If it is less than this range, there exists a tendency for crystallinity to fall and the initial irreversible capacity of a battery increase.

(2) ash

Ash content contained in graphite particle is 1 mass% or less normally with respect to the gross mass of graphite particle, Preferably it is 0.5 mass% or less, More preferably, it is 0.1 mass% or less. Moreover, it is 1 ppm or more normally.

When there is too much ash, battery performance tends to deteriorate with reaction with the electrolyte solution at the time of charge / discharge of a non-aqueous secondary battery. In addition, too little ash requires a lot of time, energy, and equipment for pollution prevention, and the cost also tends to rise to an undesired range as an industrial product.

(3) Volume-based average particle diameter (d50)

The average particle diameter (d50) on a volume basis determined by laser diffraction and scattering of graphite particles is usually 15 µm or more, preferably 18 µm or more, more preferably 19 µm or more, further preferably 20 µm or more, particularly Preferably it is 23 micrometers or more. D50 is usually 100 µm or less, preferably 50 µm or less, more preferably 40 µm or less, still more preferably 35 µm or less, particularly preferably 31 µm or less.

If the average particle diameter d50 is too small, there is a tendency to increase the irreversible capacity of the non-aqueous secondary battery and to lose the initial battery capacity. In addition, when the average particle diameter d50 is too large, it may cause process inconvenience such as streaking in slurry coating, deterioration of high current density charge / discharge characteristics of the battery, and deterioration of low temperature input / output characteristics. In particular, in the present invention, it is preferable to use graphite particles having a volume-based average particle diameter (d50) in the above-mentioned range as a raw material of the multilayer structure carbon material.

(4) Raman R value and Raman half width

The Raman R value of the graphite particles is usually 0.01 or more, preferably 0.03 or more, more preferably 0.10 or more, and usually 0.60 or less, preferably 0.50 or less, and more preferably 0.40 or less.

If the Raman R value is too small, the crystallinity of the particle surface becomes too high, and there is a tendency that there are fewer sites where Li enters between layers with charging and discharging of the non-aqueous secondary battery. That is, there exists a tendency for filling importability to fall. On the other hand, when the Raman R value is too large, the crystallinity of the particle surface decreases and the reactivity with the electrolyte solution increases, which tends to cause a decrease in efficiency and an increase in gas generation.

The Raman half width in the vicinity of 1360 cm ⁻¹ of the graphite particles is not particularly limited, but is usually 10 cm ⁻¹ or more, preferably 15 cm ⁻¹ or more. The Raman half width is usually in the range of 90 cm ^-1 or less, preferably 70 cm ^-1 or less, and more preferably 60 cm ^-1 or less.

When the Raman half value width is too small, the crystallinity of the particle surface becomes too high, and there exists a tendency for the site which Li enters between layers with charge and discharge to be small. That is, there exists a tendency for charge importability to fall. On the other hand, when the Raman half-value width is too large, the crystallinity of the particle surface decreases and the reactivity with the electrolyte solution increases, which tends to cause a decrease in efficiency and an increase in gas generation.

In addition, the measuring method of a Raman R value and a Raman half value width is as above-mentioned.

(5) BET specific surface area

The specific surface area measured using the BET method of the graphite particles is usually 0.1 m ² / g or more, preferably 0.7 m ² / g or more, more preferably 1 m ² / g or more, and still more preferably 2m ² / g That's it. In addition, the specific surface area is usually 100 m ² / g or less, preferably 25 m ² / g or less, more preferably 20 m ² / g or less, still more preferably 15 m ² / g or less, particularly preferably 10 m ² / g or less And most preferably 7 m ² / g or less.

If the specific surface area value is too small, the water solubility of lithium ions tends to deteriorate during charging of the non-aqueous secondary battery when the multilayer structure carbon material is used as the negative electrode material. On the other hand, if the specific surface area value is too large, the reactivity between the portion exposed to the electrolyte solution and the electrolyte solution in the nonaqueous secondary battery increases, and gas generation tends to increase, resulting in a difficulty in obtaining a preferable battery.

In addition, when the proportion of the carbonaceous material is increased in order to reduce the BET specific surface area of the multilayer structure carbonaceous material, excessive amorphousness is used, which tends to make it difficult to obtain high output characteristics in a battery.

(6) pore distribution

The amount of the intergranular pores corresponding to the diameter of 0.01 µm or more and 1 µm or less obtained by the mercury porosimetry (mercury porosimetry) of the graphite particles and the unevenness by the step of the particle surface is usually 0.01 mL / g or more, preferably 0.05 mL / g or more, More preferably, it is 0.1 mL / g or more. The amount is usually in the range of 0.6 mL / g or less, preferably 0.4 mL / g or less, more preferably 0.3 mL / g or less.

If it exceeds this range, a large amount of binders may be required at the time of pole plate printing. On the other hand, when the amount of the unevenness is too small, the high current density charge / discharge characteristics of the non-aqueous secondary battery are not only deteriorated, but also there is a tendency that the expansion and contraction relaxation effect of the electrode during charging and discharging cannot be obtained.

In addition, the total pore volume of the graphite particles is usually 0.1 mL / g or more, preferably 0.2 mL / g or more, and more preferably 0.25 mL / g or more. In addition, the total pore volume is usually 10 mL / g or less, preferably 5 mL / g or less, and more preferably 2 mL / g or less.

If the total pore volume is too large, a large amount of binder tends to be necessary at the time of polarization. On the other hand, when the total pore volume is too small, there is a tendency that the dispersing effect of the thickener and the binder is not obtained at the time of pole plate formation.

The average pore diameter of the graphite particles is usually 0.05 µm or more, preferably 0.1 µm or more, more preferably 0.5 µm or more, and still more preferably 0.75 µm or more. Moreover, an average pore diameter is 50 micrometers or less, Preferably it is 20 micrometers or less, More preferably, it is 10 micrometers or less.

If the average pore diameter is too large, a large amount of binder tends to be necessary, while if the average pore diameter is too small, the high current density charge / discharge characteristics of the battery tend to be lowered.

(7) roundness

The circularity of the graphite particles is usually at least 0.6, preferably at least 0.7, particularly preferably at least 0.8, more preferably at least 0.85, even more preferably at least 0.88, particularly preferably at least 0.90, most preferably at 0.91. That's it. The circularity is usually 1 or less, preferably 0.99 or less, and more preferably 0.98 or less.

If the circularity is too small, the high current density charge / discharge characteristics of the non-aqueous secondary battery tend to be lowered.

The method of improving the circularity is not particularly limited, but as described above, a method of performing spheroidization is preferable. Examples thereof include a method of mechanically making the sphere close to a spherical shape by applying a shear force and a compressive force, and a plurality of fine particles as binders or particles. The mechanical and physical processing method etc. which assemble by the adhesive force which it has are mentioned.

(8) true density

The true density of the graphite particles is usually 2 g / cm ³ or more, preferably 2.1 g / cm ³ or more, more preferably 2.2 g / cm ³ or more, still more preferably 2.22 g / cm ³ or more, and the upper limit is 2.26. g / cm ³ . This upper limit is a theoretical value of graphite.

If the true density is too small, the carbon crystallinity in the graphite particles is so low that the initial irreversible capacity of the non-aqueous secondary battery tends to increase.

The true density in this invention is defined as what was measured by the liquid-phase substitution method (Pinometer method) using butanol.

(9) tap density

It is desired that the tap density of the graphite particles is usually 0.67 g / cm ³ or more, preferably 0.7 g / cm ³ or more, more preferably 0.8 g / cm ³ or more, particularly preferably 0.88 g / cm ³ or more. In addition, the tap density is usually 1.5 g / cm ³ or less, preferably 1.4 g / cm ³ or less, more preferably 1.2 g / cm ³ or less, and particularly preferably 1.1 g / cm ³ or less.

If the tap density is too small, the packing density is difficult to increase when the multilayer structure carbon material of the present invention is used as the negative electrode forming material, and it is difficult to obtain a high capacity non-aqueous secondary battery. On the other hand, if the tap density is too large, the negative electrode There is a tendency that the interparticle gaps become too small and the conductivity between the particles is difficult to be secured, thereby making it difficult to obtain desirable battery characteristics.

In particular, in the present invention, it is preferable to use graphite particles having a tap density in the above-described range as a raw material of the multilayer structure carbon material.

(10) orientation ratio

The orientation ratio in the powder state of graphite particle is 0.01 or more normally, Preferably it is 0.02 or more, More preferably, it is 0.04 or more and an upper limit is 0.67. If the orientation ratio is too small, the high density charge and discharge characteristics of the non-aqueous secondary battery tend to be lowered.

(11) aspect ratio

The aspect ratio in the powder state of the graphite particles is usually 1 or more, usually 10 or less, preferably 8 or less, and more preferably 5 or less. If the aspect ratio is too large, streak dragging occurs at the time of polar plate printing, or a uniform coating surface is not obtained, so that the high current density charge / discharge characteristics of the non-aqueous secondary battery tend to be degraded.

(12) Average particle size d10

The particle size d10 corresponding to the cumulative 10% from the smaller particle side on the basis of the volume of the graphite particles is usually 30 µm or less, preferably 20 µm or less, more preferably 17 µm or less, usually 1 µm or more, preferably 5 micrometers or more, More preferably, it is 10 micrometers or more, More preferably, it is 11 micrometers or more, Especially preferably, it is 13 micrometers or more. The measuring method of d10 is as above-mentioned.

When d10 is too small, the agglomeration tendency of the particles may become strong, resulting in process inconvenience such as increase in slurry viscosity, decrease in electrode strength in the non-aqueous secondary battery, and decrease in initial charge and discharge efficiency. Too large d10 may cause a decrease in the high current density charge and discharge characteristics and a low temperature input / output characteristic.

(13) Average particle size d90

The particle size d90 (particle diameter of 90% cumulative from the small particle side in terms of volume) of the graphite particles determined by the laser diffraction and scattering method is usually 100 µm or less, preferably 70 µm or less, and more preferably 50 µm or less. More preferably, it is 45 micrometers or less, Usually 20 micrometers or more, Preferably it is 26 micrometers or more, More preferably, it is 30 micrometers or more, More preferably, it is 34 micrometers or more. The measuring method of d90 is as above-mentioned.

In general, the large-diameter graphite has a large d90, which tends to cause streaking at the time of slurry coating containing the multilayer structure carbon material of the present invention. It is also important to express the effect of the present invention so that d90 of the graphite particles is not as large as possible.

Too small d90 may cause a decrease in electrode strength or a decrease in initial charge and discharge efficiency in a non-aqueous secondary battery, and too large d90 may cause process inconvenience such as streaking at the time of slurry application and high current density charging of the battery. The discharge characteristic may be lowered and the low temperature input / output characteristic may be reduced.

(14) Maximum particle diameter dmax

The maximum particle diameter dmax of the graphite particles is usually 300 µm or less, preferably 250 µm or less, and more preferably 100 µm or less. Too large dmax tends to cause streaking. The measuring method of dmax is as above-mentioned.

(Method for producing graphite particles)

The graphite particles described above are composed of graphite particles containing at least one of natural graphite and artificial graphite as raw materials or coal-based coke, petroleum coke, furnace black, acetylene black, and pitch-based carbon fiber, which are slightly less crystalline than these. It is preferable to contain at least one of the baking products and graphitized materials of the material selected from the group, and more preferably graphite particles containing at least one of natural graphite and artificial graphite as raw materials. Among these, spheroidized natural graphite, which has been spheroidized with respect to natural graphite, is particularly preferable as the graphite particles.

As the apparatus used for the spheroidizing treatment, for example, an apparatus which repeatedly applies mechanical particles such as compression, friction, and shear force, including impact of a particle, as a main component, can be used. Recent advances in the spheronization treatment technology have made it possible to spheronize the graphite without making it so small.

Specifically, a device having a rotor provided with a plurality of blades inside the case, and subjected to surface treatment by applying mechanical action such as impact compression, friction, and shear force to the graphite particle raw material introduced therein as the rotor rotates at a high speed. Is preferred.

Moreover, the apparatus which has a mechanism which gives a mechanical action repeatedly as a raw material is circulated is preferable. Preferred apparatuses include, for example, hybridization systems (manufactured by Nara Machinery Co., Ltd.), kryptron (manufactured by Earth Technica), CF mill (manufactured by Ubekosan), mechanofusion system (manufactured by Hosokawa Micron), theta composer. (theta composer) (manufactured by Tokuju Works Co., Ltd.). Among them, a hybridization system manufactured by Nara Machinery Co., Ltd. is preferable.

As the graphite particles are spheronized, the flaky natural graphite is folded, or as the peripheral edges are spherically crushed, the spherical mother particles are attached to the spherical mother particles, which are mainly 5 μm or less. It is preferable to manufacture by performing a spheroidization process on condition that the surface functional group amount O / C value of the graphite particle after spheroidization becomes 1% or more and 4% or less.

At this time, it is preferable to perform a spheroidizing treatment in an active atmosphere so that the oxidation reaction of the graphite surface can be advanced by the energy of mechanical treatment to introduce an acidic functional group into the graphite surface. For example, when processing using the apparatus described above, the circumferential speed of the rotating rotor is preferably 30 to 100 m / sec, more preferably 40 to 100 m / sec, more preferably 50 to 100 m / sec. It is more preferable to make it the candle.

If the circumferential speed is too fast, the d50 tends to be too small due to hyperpulverization, and if the circumferential speed is too slow, the roundness is less likely due to insufficient spheroidization treatment.

In addition, the mechanical treatment can be performed by simply passing the graphite particles through the spheronization treatment apparatus, but it is preferable to treat by circulating or retaining the inside of the device for 30 seconds or more, and to treat the circulating or holding inside the device for 1 minute or more. More preferred. If the residence time is too long, the d50 tends to be too small due to hyperpulverization, and if the residence time is too short, the rounding treatment tends to be low due to insufficient spheroidization treatment. As a result of this strong spheronization treatment, the fine powder is greatly removed. As a result, graphite particles having a high circularity and a high tap density, and further, a multilayer structure carbon material having a high circularity and a high tap density are obtained. It is possible to obtain.

Further, if necessary, removing fine powder or crude powder by classification treatment yields graphite particles having a high circularity and a high tap density, and a multilayer structure carbon material having a high circularity and a high tap density. It is preferable because it allows.

Although there is no restriction | limiting in particular as an apparatus used for classification processing, For example, in the case of dry screening, a rotary sieve, a shake-type sieve, an agitating sieve, a vibrating sieve, an air blow feed sieve etc. can be used, and dry airflow In the case of a food classification, a gravity classifier, an inertial classifier, and a centrifugal classifier (classifier, cyclone, etc.) can be used. In the case of wet quarters, mechanical wet classifiers, hydraulic classifiers, sedimentation classifiers, centrifugal wet classifiers and the like may be used. It is more preferable to use an air blow feed sieve from both aspects of classification accuracy and productivity. By high classification accuracy, only coarse particles can be removed without reducing d50.

When manufacturing the multilayer structure carbon material of this invention, it is more preferable to use the graphite particle which performed this process as nuclear graphite.

Specific examples of the artificial graphite include coal tar pitch, coal heavy oil, atmospheric residual oil, petroleum heavy oil, aromatic hydrocarbon, nitrogen-containing cyclic compound, sulfur-containing cyclic compound, polyphenylene, polyvinyl chloride, polyvinyl alcohol, poly Organic materials such as acrylonitrile, polyvinyl butyral, natural polymer, polyphenylene sulfide, polyphenylene oxide, furfuryl alcohol resin, phenol formaldehyde resin, imide resin, etc. The thing baked and graphitized is mentioned.

As graphite particles having a small degree of graphitization, those obtained by firing an organic substance at a temperature of 600 ° C to 2500 ° C are usually used. Specific examples of the organic substance include coal-based heavy oil such as coal tar pitch and liquefied liquefied oil; DC-based heavy oils, such as atmospheric residual oil and vacuum residual oil; Petroleum heavy oils, such as cracking heavy oils such as ethylene tar, which are by-products during thermal decomposition of crude oil and naphtha; Aromatic hydrocarbons such as acenaphthylene, decacyclene and anthracene; Nitrogen-containing cyclic compounds such as phenazine and acridine; Sulfur-containing cyclic compounds such as thiophene; Aliphatic cyclic compounds such as adamantane; Polyvinyl esters, such as polyphenylene, such as biphenyl and terphenyl, polyvinyl chloride, polyvinyl acetate, and polyvinyl butyral, thermoplastic polymers, such as polyvinyl alcohol, etc. are mentioned.

In addition, when obtaining the graphite particle with a small graphitization degree, the baking temperature of an organic substance is 600 degreeC or more normally, Preferably it is 900 degreeC or more, More preferably, it is 950 degreeC or more. The upper limit is different depending on the desired degree of graphitization applied to the multilayer structure carbon material and the like, but is usually 2500 ° C, preferably 2000 ° C, and more preferably 1400 ° C. When baking, you may mix acids, such as phosphoric acid, a boric acid, hydrochloric acid, and alkalis, such as sodium hydroxide, with an organic substance.

As the graphite particles, particles such as metal particles and metal oxide particles may be appropriately mixed and used. In addition, a plurality of materials may be mixed in each particle. For example, the graphite particles used in the present invention may be carbonaceous particles having a structure in which the surface of the graphite is coated with a carbon material having a low graphitization degree, or particles which have been regraphitized by collecting the graphite particles in a suitable organic material. . Moreover, the metal which can alloy with Li, such as Sn, Si, Al, Bi, may also be included in such composite particle | grains.

Carbonaceous substance

In the multilayer structure carbonaceous material for nonaqueous secondary batteries of the present invention, the carbonaceous material covers at least part of the surfaces of the graphite particles described above. In addition, as said carbonaceous material, amorphous carbon and a graphitized material are mentioned by the different heating temperature in the manufacturing method mentioned later.

Specifically, the carbonaceous substance can be obtained by heat treating the carbon precursor as described later. As said carbon precursor, the carbon material as described in the following (a) or (b) is preferable.

(a) carbonizable organic substances selected from the group consisting of coal heavy oil, dc heavy oil, cracked petroleum heavy oil, aromatic hydrocarbons, N-ring compounds, S-ring compounds, polyphenylenes, organic synthetic polymers, natural polymers, thermoplastic resins and thermosetting resins

(b) dissolving carbonizable organics in low molecular organic solvents

The coal-based heavy oil is preferably coal tar pitch from soft pitch to light pitch, dry liquified liquefied oil, and the like, and the direct-current heavy oil is preferably atmospheric pressure residual oil, reduced pressure residual oil, and the like. As for ethylene tar which is a by-product of thermal decomposition of crude oil, naphtha, etc., etc. are preferable, As said aromatic hydrocarbon, acenaphthylene, decacyclene, anthracene, phenanthrene, etc. are preferable, As said N-ring compound, phenazine , Acridine and the like, thiophene, bithiophene and the like are preferable as the S-ring compound, biphenyl and terphenyl are preferable as the polyphenylene, and polychlorinated as the organic synthetic polymer. Vinyl, polyvinyl alcohol, polyvinyl butyral, insolubilized products of these, polyacrylonitrile, polypyrrole, polythiophene, polystyrene, and the like are preferred, and the above-mentioned natural high Jars are preferably polysaccharides such as cellulose, lignin, mannan, polygalacturonic acid, chitosan, saccharose, and the like, and as the thermoplastic resin, polyphenylene sulfide, polyphenylene oxide, and the like are preferred, and as the thermosetting resin, Prill alcohol resin, phenol-formaldehyde resin, imide resin, etc. are preferable.

Moreover, it is preferable that the said carbon precursor is carbides, such as a solution dissolved in low molecular organic solvents, such as benzene, toluene, xylene, quinoline, and n-hexane.

(Physical properties of amorphous carbon)

As described above, the carbonaceous material used in the present invention is amorphous carbon or graphitized material depending on the difference in heating temperature in its manufacture, but the amorphous carbon is any one or a plurality of conditions (1) to (4) shown below. It is desirable to satisfy. In the present invention, one kind of amorphous carbon showing such physical properties may be used alone, or two or more kinds thereof may be used in any combination.

(1) X-ray parameter

About amorphous carbon, it is preferable that d002 value (interlayer distance) of the grating plane (002 surface) calculated | required by X-ray diffraction by the Hakjin method is 0.340 nm or more, and it is especially preferable that it is 0.341 nm or more. The d002 value is usually 0.380 nm or less, preferably 0.355 nm or less, and more preferably 0.350 nm or less.

If the value of d002 is too large, the surface becomes remarkably low in crystallinity, and the irreversible capacity tends to increase in the non-aqueous secondary battery. On the other hand, if the value of d002 is too small, the charge importability obtained by disposing the low crystalline carbonaceous material on the surface The effect of improvement is small and there exists a tendency for the effect of this invention to become small.

In addition, the crystallite size (Lc) determined by X-ray diffraction by the method of amorphous carbon is usually 1 nm or more, preferably 1.5 nm or more. If it is less than this range, crystallinity may fall and the increase of the initial irreversible capacity of a battery may increase.

(2) ash

The ash contained in the amorphous carbon portion is usually 0.1% by mass or less, preferably 0.01% by mass or less, and more preferably 0.001% by mass or less, based on the total mass of the multilayer structure carbon material of the present invention. In addition, ash content is 0.1 ppm or more normally.

If the ash content is too small, a lot of time, energy, and pollution prevention equipment are required for the production of the multilayer structure carbon material, and the cost tends to rise to an undesired range as an industrial product.

(3) Raman R value and Raman half width

Raman R value of amorphous carbon is 0.5 or more normally, Preferably it is 0.7 or more, More preferably, it is 0.9 or more. Moreover, Raman R value is 1.5 or less normally, Preferably it is 1.4 or less.

When Raman R value is too small, the crystallinity of the particle | grain surface of the multilayer structure carbon material of this invention becomes high too much, and there exists a tendency for the site which Li ion enters between layers with charge and discharge of a non-aqueous secondary battery. That is, there exists a tendency for charge importability to fall. In addition, when the negative electrode is densified by applying a slurry containing the multilayer structure carbon material of the present invention to a current collector and pressing, the crystal tends to be oriented in parallel with the electrode plate, and the load characteristics tend to be lowered.

On the other hand, when Raman R value is too large, the crystallinity of the particle surface of a carbon material will fall, reactivity with electrolyte solution will increase, and there exists a tendency for efficiency fall and gas generation to increase.

The Raman half width in the vicinity of 1580 cm ⁻¹ of the amorphous carbon portion is not particularly limited, but is usually 60 cm ⁻¹ or more, preferably 80 cm ⁻¹ or more, and usually 150 cm ⁻¹ or less, preferably 140 cm ⁻¹ or less.

If the Raman half-value width is too small, the crystallinity of the surface of the carbon material particles becomes too high, and there is a tendency that there are fewer sites where Li ions enter between layers with charging and discharging of the battery. That is, there exists a tendency for charge importability to fall.

When the negative electrode is densified by applying a slurry to the current collector and then pressing, crystals tend to be oriented in a direction parallel to the electrode plate, which may cause a decrease in load characteristics. On the other hand, when the Raman half width is too large, the crystallinity of the surface of the carbon material particles decreases and the reactivity with the electrolyte increases, which tends to cause a decrease in efficiency and an increase in gas generation.

In addition, the measuring method of a Raman R value and a Raman half value width is as above-mentioned.

(4) true density

The true density of the amorphous carbon portion is usually 1.4g / cm ³ or more, preferably 1.5g / cm ³ or more, more preferably 1.6g / cm ³ or more, more preferably 1.7g / cm ³ or more, typically 2.1 g / cm ³ or less, Preferably it is 2g / cm ³ or less.

If the true density is too large, the charge importability of the non-aqueous secondary battery tends to be deteriorated. On the other hand, if the true density is too small, the crystallinity of the carbon constituting the amorphous carbon is so low that the initial irreversible capacity of the battery tends to increase.

(Physical Properties of Graphite)

As described above, the carbonaceous material used in the present invention is amorphous carbon or graphitized material according to the difference in heating temperature in the production thereof, but the graphitized material is any one or a plurality of conditions (1) to (4) shown below. It is desirable to be satisfied. In the present invention, one type of graphitized material showing such physical properties may be used alone, or two or more types may be used in any combination.

(1) X-ray parameter

As for the graphitized product, it is preferable that the d002 value (interlayer distance) of the grating plane (002 plane) determined by X-ray diffraction by the Hakjin method is 0.340 nm or less, and more preferably 0.337 nm or less. On the other hand, since the theoretical value of the space | interval between planes of the 002 plane of graphite is 0.335 nm, the said d value is 0.335 nm or more normally.

If the value of d002 is too large, the surface becomes remarkably low in crystallinity, and the irreversible capacity tends to increase in the non-aqueous secondary battery. On the other hand, if the value of d002 is too small, the effect of improving the charge importability obtained by arranging the graphite on the surface is small. There exists a tendency for the effect of this invention to become small.

In addition, the crystallite size (Lc) determined by X-ray diffraction by graphene method is usually 1 nm or more, preferably 1.5 nm or more. If it is less than this range, crystallinity may fall and the increase of the initial irreversible capacity of a battery may increase.

(2) ash

The ash contained in the graphitized part is usually 0.1% by mass or less, preferably 0.01% by mass or less, and more preferably 0.001% by mass or less with respect to the total mass of the multilayer structure carbon material of the present invention. In addition, ash content is 0.1 ppm or more normally.

If the ash content is too small, a lot of time, energy, and pollution prevention equipment are required for the production of the multilayer structure carbon material, and the cost tends to rise to an undesired range as an industrial product.

(3) Raman R value and Raman half width

Raman R value of graphite is normally 0.5 or more, Preferably it is 0.7 or more, More preferably, it is 0.9 or more. Moreover, Raman R value is 1.5 or less normally, Preferably it is 1.4 or less.

If the Raman R value is too small, the crystallinity of the particle surface of the multilayer structure carbonaceous material of the present invention becomes too high, and there is a tendency that fewer sites enter Li ions between layers due to charge and discharge of the non-aqueous secondary battery. . That is, there exists a tendency for charge importability to fall. In addition, when the negative electrode is densified by applying a slurry containing the multilayer structure carbon material of the present invention to a current collector and pressing, the crystal tends to be oriented in parallel with the electrode plate, and the load characteristics tend to be lowered.

On the other hand, when Raman R value is too large, the crystallinity of the particle surface of a carbon material will fall, reactivity with electrolyte solution will increase, and there exists a tendency for efficiency fall and gas generation to increase.

The Raman half width in the vicinity of 1580 cm ⁻¹ of the graphitized portion is not particularly limited, but is usually 60 cm ⁻¹ or more, preferably 80 cm ⁻¹ or more, and usually 150 cm ⁻¹ or less, preferably 140 cm ⁻¹ or less.

If the Raman half-value width is too small, the crystallinity of the surface of the carbon material particles becomes too high, and there is a tendency that there are fewer sites where Li ions enter between layers with charging and discharging of the battery. That is, there exists a tendency for charge importability to fall.

In addition, in the case where the negative electrode is made densified by applying the slurry to the current collector and then pressing, crystals tend to be oriented in the direction parallel to the electrode plate, and there is a tendency to cause a decrease in load characteristics. On the other hand, when the Raman half width is too large, the crystallinity of the surface of the carbon material particles decreases and the reactivity with the electrolyte increases, which tends to cause a decrease in efficiency and an increase in gas generation.

In addition, the measuring method of a Raman R value and a Raman half value width is as above-mentioned.

(4) true density

The true density of the graphite part of the cargo is usually 1.4g / cm ³ or more, preferably 1.5g / cm ³ or more, more preferably 1.6g / cm ³ or more, more preferably 1.7g / cm ³ or more, typically 2.1 g / cm ³ or less, Preferably it is 2g / cm ³ or less.

If the true density is too large, the charge importability of the non-aqueous secondary battery tends to be deteriorated. On the other hand, if the true density is too small, the crystallinity of the carbon constituting the graphite is too low, and the initial irreversible capacity of the battery tends to increase.

<Manufacture of multilayer structure carbon material>

The manufacturing method of the multilayer structure carbon material of this invention coat | covers at least one part of the surface of a graphite particle with a carbonaceous material, and the obtained multilayer structure carbon material has an average particle diameter d50 of 19.1 micrometers or more and 50 micrometers or less, and circularity is 0.88 or more The ratio of the rolling load P to the d50 of the carbon material is 30 or less, and the method is not particularly limited as long as the deposition amount of the carbonaceous material is 0.01 to 2.7 mass%.

More specifically, the method for producing a multilayer structure carbon material uses the above-mentioned graphite particles as nuclear graphite, uses a carbon precursor for obtaining a carbonaceous material as a coating material, mixes and calcinates them, and combines these raw materials to provide specific The multilayer structure carbon material of this invention can be manufactured by controlling various conditions so that an amount of deposition may be carried out.

The method of coating the graphite particles with the carbonaceous material is a method of obtaining a composite powder by heat treating the mixture of the carbon precursor and the graphite particle powder using the carbon precursor to obtain the carbonaceous material as it is, and the carbon precursor described above with some carbon A method of preparing the carbonaceous material powder prepared in advance and mixing the mixture with the graphite particle powder, followed by heat treatment to composite the carbonaceous material powder. The method of mixing, heat-processing, and compounding can be employ | adopted.

In addition, it is preferable to use the carbonaceous substance whose average particle diameter d50 is one tenth or less of the average particle diameter d50 of graphite particle | grains as a method of preparing the latter two carbonaceous substance powder previously. In addition, by applying mechanical energy such as pulverization to the carbonaceous material and the graphite particles produced in advance, a method in which the other is mixed on one side or a method in which the structure is electrostatically attached can also be adopted.

A mixture of graphite particles and a carbon precursor is obtained or a mixture of graphite particles and a carbonaceous material and a carbon precursor is heated to obtain an intermediate material, and then carbonized and pulverized to finally form carbon in the graphite particles. It is desirable to obtain a multilayer structure carbon material obtained by complexing (coating) a material material.

The process of an example of the manufacturing method for obtaining the multilayer structure carbon material in this invention more concretely can be divided into the following four processes.

1st process: The carbon precursor of a graphite particle and a carbonaceous material, and also a solvent are mixed using various commercially available mixers, kneading machines, etc. as needed, and a mixture is obtained.

Second Step: The mixture is heated to obtain an intermediate that removes volatiles from the solvent and carbon precursor. This heating may be performed while stirring the said mixture as needed. Moreover, even if the said volatile matter remains, since it removes in a subsequent 3rd process, there is no problem.

Third step: The mixture or intermediate is heated from 400 ° C. to 3200 ° C. under a gas atmosphere such as nitrogen gas, carbon dioxide gas, argon gas, gas mixture atmosphere or the like from the mixture or intermediate material to obtain a multilayer structure carbon material.

4th process: The said multilayer structure carbon material is powder-processed, such as grinding | pulverization, crushing, classification processing, as needed.

Among these steps, the second step and the fourth step may be omitted depending on the case, and the fourth step may be performed before the third step. However, in the case where the fourth step is carried out before the third step, if necessary, after the end of the third step, powder processing such as pulverization, pulverization, and classification treatment is performed again to obtain a multilayer structure carbon material.

The apparatus used for the heat treatment of the third process raw material is not particularly limited, but for example, a shuttle furnace, a tunnel furnace, a leadhammer furnace, a rotary kiln, Reactors, such as an autoclave, coca (coke heat processing tank), a Tammann furnace, and an Acheson furnace, can be used.

The heating method of the heat treatment apparatus is also not particularly limited, and may be a high frequency induction heating furnace, direct resistance heating, indirect resistance heating, direct combustion heating, radiant heat heating, or the like.

In addition, you may perform stirring at the time of heat processing. In addition, heat history temperature conditions are important as heat treatment conditions. The lower limit of the temperature is slightly different depending on the kind of the carbon precursor and its thermal history, but is usually 600 ° C, preferably 700 ° C, and more preferably 900 ° C.

On the other hand, the upper limit temperature can be raised to a temperature that basically prevents the carbon precursor from having a structural order exceeding the crystal structure of the graphite particle nucleus. Therefore, as an upper limit temperature of heat processing, it is 3200 degreeC, Preferably it is 2000 degreeC, More preferably, it is 1500 degreeC, More preferably, it is 1200 degreeC.

In particular, the heat treatment is usually at least 600, preferably at least 700, more preferably at least 900, usually at most 2000, preferably at most 1500, and more preferably at most 1200C. Carbon is obtained, and heat treatment is usually performed at 2000 ° C. or higher, preferably 2500 ° C. or higher, and usually 3200 ° C. or lower to obtain a graphitized material as a carbonaceous substance. The amorphous carbon is carbon having low crystallinity, and the graphitized material is carbon having high crystallinity.

Under such heat treatment conditions, the heat history temperature conditions, the temperature increase rate, the cooling rate, the heat treatment time, and the like are appropriately set so that the amount of the carbonaceous substance adheres in the above-described range. The adjustment method of the said adhesion amount is well-known, As an example, adjusting the quantity of the graphite particle and carbon precursor mixed in the said 1st process is mentioned.

It is also possible to heat up at a predetermined temperature after heat treatment in a relatively low temperature region. In addition, the reactor used in this process may be a batch type or a continuous type, and may be a single group or a plurality of groups.

Furnaces available for the third process are not particularly limited as long as the above requirements are met.

Although there is no restriction | limiting in particular in the apparatus used for the grinding | pulverization of a 4th process, For example, a rough mill, a jaw crusher, an impact crusher, a cone crusher etc. are mentioned as a rough grinder, An intermediate grinder As a mill, a roll crusher, a hammer mill, etc. are mentioned, A mill, a ball mill, a vibration mill, a pin mill, a stirring mill, a jet mill etc. are mentioned.

There is no restriction | limiting in particular as an apparatus used for the classification process of a 4th process, For example, in the case of a dry quadrant, a rotary sieve, a shake-type sieve, an agitating sieve, a vibrating sieve, etc. can be used, In the case of a dry airflow classification Gravity classifiers, inertial classifiers, centrifugal classifiers (classifiers, cyclones, etc.) can be used, and wet quarters, mechanical wet classifiers, hydraulic classifiers, sediment classifiers, centrifugal wet classifiers, etc. It is available.

Although there is no restriction | limiting in particular as an apparatus used for the disintegration of a 4th process, The ball mill, the vibration mill, the pin mill, the stirring mill, the jet mill, etc. which use roll crusher, a hammer mill, etc., and also the compression which mainly contained the interaction of particle | grains by the impact force Apparatus for repeating mechanical action such as friction, shearing force and shear force, for example, hybridization system (manufactured by Nara Machinery Co., Ltd.), kryptron (manufactured by Earth Technica), CF mill (manufactured by Ubekosan), mecha Nofusion system (product of Hosokawa Micron Co., Ltd.) and theta composer (product of Tokuju Works Co., Ltd.) can be used, and this process is performed by appropriately adjusting the strength so that the particle size of primary particles is not too small before and after the aggregate disintegration treatment. Can be disintegrated.

<Member>

In addition to the multilayer structure carbon material described above, the multilayer structure carbon material of the present invention can further improve battery performance by containing at least one carbonaceous material (carbonaceous material) having different carbonaceous physical properties.

The above-mentioned "physical properties of carbonaceous material" means at least one of X-ray diffraction parameters, median diameter, aspect ratio, BET specific surface area, orientation ratio, Raman R value, tap density, true density, pore distribution, circularity, ash content Indicates.

In a preferred embodiment, when the volume-based particle size distribution centers on the median diameter of the carbonaceous material, symmetry is not performed, and two or more carbonaceous materials having different Raman R values are used. The use of 2 or more types of carbonaceous materials from which a parameter differs is mentioned.

Examples of the effects of using a carbonaceous material include carbonaceous materials such as graphite (graphite) such as natural graphite and artificial graphite, carbon black such as acetylene black, and amorphous carbon such as needle coke as a member, and the like. Reducing the electrical resistance of the non-aqueous secondary battery obtained using the multilayer structure carbon material mentioned above, etc. are mentioned.

The carbonaceous material demonstrated above may be used individually by 1 type, or may use 2 or more types together by arbitrary combinations and a ratio. When adding a carbonaceous material to a member, it is 0.1 mass% or more normally with respect to 100 mass% of all the multilayer structure carbon materials containing a member, Preferably it is 0.5 mass% or more, More preferably, it is 0.6 mass% or more, Usually 80 mass% Hereinafter, Preferably it is 50 mass% or less, More preferably, it is 40 mass% or less, More preferably, it adds in the quantity of 30 mass% or less.

If it is less than this range, it exists in the tendency for a battery to acquire electroconductive improvement effect. On the other hand, exceeding this range too much may result in the increase of the initial irreversible capacity of a battery.

[Electrode production]

The production of the electrode may be in accordance with a conventional production method. For example, a binder, a solvent, a thickener, a conductive material, a filler, and the like are added to the multilayer structure carbon material of the present invention to form a slurry, which is applied to the current collector, dried, and then pressed to form the multilayer structure carbon on the current collector. A negative electrode can be manufactured by forming a material layer.

Here, as described in the problem to be solved by the present invention, in order to achieve a high capacity in the non-aqueous secondary battery and to uniform the thickness of the negative electrode plate, it is necessary to apply rolling at a certain pressure or more. In the material, this pressure causes damage to the material, resulting in material destruction, increasing the negative reaction with the electrolyte, decreasing the initial efficiency in the battery, and increasing the irreversible charge / discharge capacity during the initial cycle, resulting in higher capacity. There was a problem that he could not achieve due to manipulation.

The multilayer structure carbon material of this invention has a comparatively large average particle diameter d50 of 19.1-50 micrometers, and there is little amount of the carbonaceous substance which coat | covers the graphite particle which is a nucleus of a carbon material. When such a carbon material is manufactured from the slurry by the negative electrode, uniformity of the thickness of the electrode plate is achieved even by rolling under pressure such that material destruction does not occur, and a sufficient high capacity is achieved because the initial irreversible capacity of the battery is small.

Specifically, in the case of producing a negative electrode by using the multilayer structure carbon material of the present invention as a negative electrode active material, the linear pressure required to roll so that the density of the negative electrode active material layer is 1.6 g / cm ³ is usually 550 kg / 5 cm or less, preferably Preferably it is 500 kg / 5 cm or less, More preferably, it is 450 kg / 5 cm or less, More preferably, it is 400 kg / 5 cm or less, and usually 100 kg / 5 cm or more. In addition, linear pressure means the force per unit length (it is set to 5 cm in this specification) of the axial direction of the roll used for rolling.

When the linear pressure required for rolling the negative electrode active material layer to be 1.6 g / cm ³ is in the above range, the damage to the carbon material is suppressed, so that the initial efficiency increases in the battery, and is caused by side reaction between the negative electrode and the electrolyte solution. Initial gas is reduced. In addition, the carbon material particles are appropriately deformed by rolling with a suitable pressure, the contact area between the particles increases, and the adhesion strength of the electrode is improved. Since the particle diameter of the multilayer structure carbon material of the present invention is large and the amount of carbonaceous material covering the graphite particles, which is the core of the carbon material, is small, the carbon strength is softer than that of the conventional carbon material. Contributes to improvement.

Specifically, the pole plate strength of the negative electrode obtained by using the multilayer structure carbon material of the present invention is usually 3 mN / mm or more, preferably 5 mN / mm or more, more preferably 7 mN / mm or more, even more preferably 10 mN / mm As mentioned above, it is 100 mN / mm or less normally, Preferably it is 50 mN / mm or less, More preferably, it is 30 mN / mm or less. If the value is too small, peeling of the negative electrode active material layer from the current collector tends to occur, which tends to impair the processability significantly. If the value is too large, the negative electrode loses its flexibility and the negative electrode active material layer is not peeled off during bending or rolling of the negative electrode. This tends to significantly impair fairness.

The thickness of the multilayer structure carbon material layer per side at the stage immediately before the electrolyte solution pouring process of the non-aqueous secondary battery is usually 15 µm or more, preferably 20 µm or more, more preferably 30 µm or more, and the upper limit is usually 150 µm. Preferably it is 120 micrometers, More preferably, it is 100 micrometers.

When it exceeds this range, electrolyte solution may be difficult to penetrate to the vicinity of an electrical power collector interface, and the high current density charge / discharge characteristic of a battery may fall. Moreover, if it is less than this range, there exists a tendency for the battery capacity to decrease by increasing the collector volume ratio with respect to a multilayer structure carbon material.

Moreover, you may roll shape a multilayer structure carbon material as a sheet electrode, or you may make a pellet electrode by compression molding.

[cathode]

As a current collector which holds the multilayer structure carbon material of this invention, a well-known thing can be used arbitrarily. Examples of the current collector of the negative electrode include metal materials such as copper, nickel, stainless steel, and nickel plated steel. Among them, copper is particularly preferable in view of ease of processing and cost.

In the case where the current collector is a metal material, for example, a metal foil, a metal cylinder, a metal coil, a metal plate, a metal thin film, an expanded metal, a punch metal, a foamed metal, and the like can be given. Among these, Preferably it is a metal thin film, More preferably, it is copper foil, More preferably, it is the rolled copper foil obtained by the rolling method, and the electrolytic copper foil obtained by the electrolytic method.

When the thickness of copper foil is thinner than 25 micrometers, the copper alloy (phosphor bronze, a titanium copper, a Colson alloy, a Cu-Cr-Zr alloy etc.) whose strength is higher than pure copper can be used.

Since the current collector which consists of copper foil produced by the rolling method arrange | positions a copper crystal in the rolling direction, it is hard to be broken even if the negative electrode is bent densely or bent at an acute angle, and can be used suitably for a small cylindrical battery.

The electrolytic copper foil can be obtained by, for example, immersing a metal drum in an electrolyte solution in which copper ions are dissolved, and depositing copper on the surface of the drum as a current flows while rotating it, and peeling it. It can obtain even if it deposits copper on the surface of said rolled copper foil by an electrolytic method.

One or both surfaces of the copper foil may be subjected to a roughening treatment or surface treatment (eg, chromate treatment up to several nm to about 1 μm, substrate treatment such as Ti, etc.).

In addition, the following physical properties are further required for the current collector substrate (what the multilayer structure carbon material layer is formed on the current collector).

(1) Average surface roughness (Ra)

The average surface roughness Ra of the active material layer (ie, the multilayer structure carbon material layer) forming surface of the current collector substrate specified by the method described in JISB0601-1994 is not particularly limited, but is usually 0.01 μm or more, preferably 0.03 μm or more. It is 1.5 micrometers or less normally, Preferably it is 1.3 micrometers or less, Especially preferably, it is 1.0 micrometer or less.

By setting the average surface roughness Ra of the active material layer forming surface of the current collector substrate within the range between the lower limit and the upper limit, good charge-discharge cycle characteristics can be expected in the non-aqueous secondary battery obtained by using the current collector substrate. .

By setting it as the said lower limit or more, the area of the interface of an electrical power collector and an active material layer becomes large, and these adhesiveness improves. Although the upper limit of average surface roughness Ra is not specifically limited, It is preferable that average surface roughness Ra exceeds 1.5 micrometers, since it is generally difficult to obtain with thin film of practical thickness as a battery, It is preferable that it is 1.5 micrometers or less.

(2) tensile strength

The tensile strength of the current collector substrate is not particularly limited, and usually 50N / mm ² or more, preferably 100N / mm ^2, more preferably at least 150N / mm ^2. Tensile strength is the maximum tensile force required until the specimen breaks, divided by the cross-sectional area of the specimen. Tensile strength in the present invention is measured by the same method and apparatus as the elongation measurement.

If the current collector substrate has a high tensile strength, cracking of the current collector substrate due to expansion and contraction of the active material layer due to charge and discharge can be suppressed, and favorable cycle characteristics can be obtained.

(3) 0.2% yield strength

0.2% yield strength of the current collector substrate is not particularly limited, and usually 30N / mm ² or more, preferably 100N / mm ² or more, and particularly preferably not less than 150N / mm ^2. The 0.2% yield strength means that the load required to apply a plastic (permanent) strain of 0.2% is deformed by 0.2% even if the load is removed after the load of this size is applied.

In the present invention, the 0.2% yield strength is measured by the same method and apparatus as the elongation measurement. With a current collector substrate having a high 0.2% yield strength, plastic deformation of the current collector substrate due to expansion and contraction of the active material layer due to charge and discharge can be suppressed, and good cycle characteristics can be obtained.

(4) thickness of the current collector

Although the thickness of an electrical power collector is arbitrary, it is 1 micrometer or more normally, Preferably it is 3 micrometers or more, More preferably, it is 5 micrometers or more. In addition, an upper limit is 1 mm normally, Preferably it is 100 micrometers, More preferably, it is 30 micrometers.

When the thickness of the current collector becomes thinner than 1 µm, the strength is lowered, so that application of the multilayer structure carbon material-containing slurry becomes difficult, which may be undesirable in the process. On the other hand, when it becomes thicker than 1 mm, it may become difficult to deform | transform electrode form, such as winding, in the process, and may be undesirable. In addition, a collector may be mesh-like.

(5) the ratio of the thickness of the current collector and the active material layer

Although the ratio of the thickness of an electrical power collector and the active material layer (layer containing the multilayer structure carbon material of this invention) formed on it is not specifically limited, (thickness of the active material layer of one side just before electrolyte solution injection) / (the Thickness) is 150 or less, Preferably it is 20 or less, More preferably, it is 10 or less, and a minimum is 0.1, Preferably it is 0.4, More preferably, it is 1. If it exceeds this range, the current collector may generate heat by Joule heat during high current density charge / discharge. On the other hand, if it is less than this range, the volume ratio of the electrical power collector with respect to a multilayer structure carbon material may increase, and the battery capacity may decrease.

(6) electrode density

Although the electrode structure in the case of electrodelizing the multilayer structure carbon material of this invention is not specifically limited, The density of the active material which exists on an electrical power collector becomes like this. Preferably it is 1 g / cm <^3> or more, More preferably, it is 1.1 g / cm <^3>. More than 1.2 g / cm ³ or more, and the upper limit is usually 2 g / cm ³ , preferably 1.9 g / cm ³ , more preferably 1.8 g / cm ³ , still more preferably 1.7 g / cm ^3. to be.

If it exceeds this range, the active material particles are destroyed in rolling or the like to achieve electrode density, and the initial irreversible capacity of the non-aqueous secondary battery is increased, or the permeability of the electrolyte to the vicinity of the current collector / active material interface is lowered. In some cases, the high current density charge and discharge characteristics may be deteriorated. Moreover, when less than the said range, the electroconductivity between active materials will fall, battery resistance may increase, and the capacity | capacitance per unit volume may fall.

(7) pole plate orientation ratio

The pole plate orientation ratio of the negative electrode is usually 0.01 or more, preferably 0.05 or more, more preferably 0.10 or more, and the upper limit is 0.67, which is a theoretical value. If it is less than this range, the high-density charge / discharge characteristic of a nonaqueous secondary battery may fall.

The measuring method of an electrode plate orientation ratio is as follows. The active material orientation ratio of the electrode is measured by X-ray diffraction with respect to the negative electrode after pressing at the target density. The specific method is not particularly limited, but the standard method uses X-ray diffraction to perform peak separation by fitting the peaks of (110) diffraction and (004) diffraction of carbon as a profile function and fitting them using asymmetric Pearson VII. The integrated intensities of the peaks of) diffraction and (004) diffraction are respectively calculated. From the obtained integrated intensity, the ratio represented by (110) diffraction integrated intensity / (004) diffraction integrated intensity is calculated and defined as the active material orientation ratio of the electrode.

X-ray diffraction measurement conditions here are as follows. "2θ" represents a diffraction angle.

Target: Cu (Kα-ray) graphite monochromator

Slit: divergence slit = 1 degree, light receiving slit = 0.1 mm, scattering slit = 1 degree

Measurement range and step angle / measuring time:

     (110) plane: 76.5 degrees ≤ 2θ ≤ 78.5 degrees 0.01 degrees / 3 seconds

     (004) plane: 53.5 degrees ≤ 2θ ≤ 56.0 degrees 0.01 degrees / 3 seconds

Sample preparation: Fixing the electrode with 0.1 mm thick double-sided tape on a glass plate

(8) impedance

It is preferable that the resistance of the negative electrode when charged to 60% of the nominal capacity from the discharge state is 100 Ω or less, particularly preferably 50 Ω or less, more preferably 20 Ω or less, and / or the double layer capacity is 1 × 10 ⁻⁶ F or more. It is preferable, Especially preferably, it is 1 * 10 <^-5> F or more, More preferably, it is 1 * 10 <^-4> F or more. If it is this range, the output characteristic of a non-aqueous secondary battery is favorable, and it is preferable.

The resistance and the bilayer capacity of the cathode are measured in the following order. In the non-aqueous secondary battery to be measured, after charging at a current value capable of charging the nominal capacity for 5 hours, the battery was kept without charging and discharging for 20 minutes, and then the nominal capacity was discharged for 1 hour. The capacity | capacitance at the time of discharge by electric current value uses 80% or more of nominal capacity.

For the non-aqueous secondary battery in the discharged state described above, it is charged to 60% of the nominal capacity at a current value capable of charging the nominal capacity for 5 hours, and the non-aqueous secondary battery is immediately transferred into the glove box under argon gas atmosphere. Here, the non-aqueous secondary battery is quickly disassembled and taken out in a state in which the negative electrode is not discharged or short-circuited, and if the double-coated electrode is used, the electrode active material on one side is peeled off without damaging the electrode active material on the other side. Two sheets are punched at 12.5 mm phi and faced so that the surface of the active material is not shifted through the separator.

60 µl of the electrolyte solution used in the battery was dropped between the separator and both cathodes to keep it in close contact with the outside air, and the current collectors of both anodes were subjected to the AC impedance method. The measurement is performed by measuring complex impedance in the frequency band of 10 ⁻² to 10 ⁵ Hz at a temperature of 25 ° C., and approximating the arc of the cathode resistance component of the obtained cole-cole plot with a semicircle to give a surface resistance (R). And double layer capacity (Cdl).

<Binder>

The binder for binding the active material (multilayer structure carbon material) is not particularly limited as long as it is a material that is stable with respect to a solvent used in the preparation of an electrolyte solution or an electrode. Specifically, Resin-based polymers, such as polyethylene, polypropylene, polyethylene terephthalate, polymethyl methacrylate, aromatic polyamide, cellulose, nitrocellulose; Rubber polymers such as SBR (styrene-butadiene rubber), isoprene rubber, butadiene rubber, fluorine rubber, NBR (acrylonitrile-butadiene rubber) and ethylene propylene rubber; Styrene butadiene styrene block copolymers and hydrogenated products thereof; Thermoplastic elastomeric polymers such as EPDM (ethylene-propylene-diene terpolymer), styrene-ethylene-butadiene-styrene copolymer, styrene-isoprene-styrene block copolymer, and hydrogenated products thereof; Soft dendritic polymers such as syndiotactic-1,2-polybutadiene, polyvinyl acetate, ethylene-vinyl acetate copolymer, and propylene-α-olefin copolymer; Fluorine-based polymers such as polyvinylidene fluoride, polytetrafluoroethylene, fluorinated polyvinylidene fluoride, and polytetrafluoroethylene-ethylene copolymers; The polymer composition etc. which have ion conductivity of alkali metal ion (especially lithium ion) are mentioned. These may be used individually by 1 type and may use 2 or more types together by arbitrary combinations and a ratio.

The solvent for forming the slurry is not particularly limited as long as it is a solvent capable of dissolving or dispersing an active material, a binder, a thickener and a conductive material used if necessary, and either an aqueous solvent or an organic solvent may be used. .

Examples of the aqueous solvent include water and alcohols, and examples of the organic solvent include N-methylpyrrolidone (NMP), dimethylformamide, dimethylacetamide, methyl ethyl ketone, cyclohexanone, and acetic acid. Methyl, methyl acrylate, diethyltriamine, N, N-dimethylaminopropylamine, tetrahydrofuran (THF), toluene, acetone, diethyl ether, dimethylacetamide, hexamethylphosphoamide, dimethyl sulfoxide , Benzene, xylene, quinoline, pyridine, methylnaphthalene, hexane and the like.

In particular, in the case of using an aqueous solvent, a dispersant and the like are added together with the above-described thickener and slurried using latex such as SBR. In addition, these solvent may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

The ratio of the binder to the active material is usually at least 0.1 mass%, preferably at least 0.5 mass%, more preferably at least 0.6 mass%, and the upper limit is usually 20 mass%, preferably 15 mass%, more preferably 10 It is mass%, More preferably, it is 8 mass%.

When it exceeds this range, the binder ratio which does not contribute to battery capacity may increase, and battery capacity may fall. Moreover, when less, it may cause the fall of the strength of a negative electrode, and may be undesirable in a battery manufacturing process.

In particular, in the case of containing the rubbery polymer represented by SBR as the main component of the binder, the ratio of the binder to the active material is usually at least 0.1 mass%, preferably at least 0.5 mass%, more preferably at least 0.6 mass%, An upper limit is 5 mass% normally, Preferably it is 3 mass%, More preferably, it is 2 mass%.

In addition, when the fluorine-type polymer represented by polyvinylidene fluoride is contained as a main component of a binder, the ratio of the binder with respect to an active material is 1 mass% or more normally, Preferably it is 2 mass% or more, More preferably, 3 mass% The upper limit is 15 mass% normally, Preferably it is 10 mass%, More preferably, it is 8 mass%.

The thickener is usually used to adjust the viscosity of the slurry. Although there is no restriction | limiting in particular as a thickener, Specifically, carboxymethyl cellulose, methyl cellulose, hydroxymethyl cellulose, ethyl cellulose, polyvinyl alcohol, oxidized starch, phosphorylated starch, casein, these salts, etc. are mentioned.

These may be used individually by 1 type and may use 2 or more types together by arbitrary combinations and a ratio.

In addition, when using a thickener, the ratio of the thickener with respect to an active material is 0.1 mass% or more normally, Preferably it is 0.5% or more, More preferably, it is 0.6% or more, and an upper limit is 5 mass% normally, Preferably it is 3 mass%, More Preferably it is 2 mass%. If it is less than this range, the applicability of a slurry may fall remarkably. On the other hand, when it exceeds, the ratio of the active material which occupies for a multilayer structure carbon material layer may fall, and the problem of the capacity | capacitance of a battery may fall, or the problem that resistance between multilayer structure carbon materials may increase may arise.

[Non-aqueous secondary battery]

EMBODIMENT OF THE INVENTION Hereinafter, the non-aqueous secondary battery of this invention is demonstrated in detail.

<Battery shape>

The battery shape is not particularly limited, but examples thereof include a user cylindrical shape, a user square shape, a thin shape, a sheet shape, and a paper shape. In the case of mixing in a system or an apparatus, in order to increase the volume efficiency and to increase the storage capacity, there may be a variant such as a horseshoe type or a comb shape in consideration of storage in a peripheral system arranged around the battery. From the viewpoint of efficiently dissipating heat inside the battery to the outside, a rectangular shape having a relatively flat and at least one large area surface is preferable.

In the battery having a user cylindrical shape, since the outer surface area of the power generating element to be charged is small, it is preferable to design a structure that efficiently discharges Joule heat generated by internal resistance during charging or discharging to the outside. In addition, it is preferable to increase the filling ratio of the material having a high thermal conductivity to reduce the temperature distribution therein.

In the user square shape, it is preferable that the ratio 2S / T of twice the area S of the largest surface (the product of the external dimension width and height except the terminal portion, unit m ² ) and the thickness T of the battery outline (unit m) is 100 or more. It is more preferable that it is 200 or more. Increasing the maximum surface not only improves the characteristics such as cycleability and high temperature storage, but also improves heat dissipation efficiency during abnormal heat generation in high-power and high-capacity batteries, and in dangerous states such as `` valve operation '' or `` rupture. '' Can be suppressed.

Battery configuration

The non-aqueous secondary battery of the present invention includes a positive electrode and a negative electrode capable of storing and releasing lithium ions, and a non-aqueous electrolyte, and are composed of a separator, a current collecting terminal, and an outer case disposed between the positive and negative electrodes. A protective element may be attached to at least one of the inside of the battery and the outside of the battery.

<Anode>

In the non-aqueous secondary battery of the present invention, the positive electrode forms an active material layer containing a positive electrode active material and an organic material (binder) having a binding and thickening effect on a current collector, and the positive electrode active material and the organic material are usually water or organic. What is slurry form disperse | distributed in the solvent is formed by the process of apply | coating thinly on the said electrical power collector, and the press process which consolidates to predetermined thickness and density.

The material of the positive electrode active material is not particularly limited as long as it has a function of occluding and releasing lithium ions. For example, lithium transition metal composite oxide materials such as lithium cobalt oxide, lithium nickel oxide, and lithium manganese oxide: manganese dioxide Transition metal oxide materials such as; Carbonaceous materials, such as graphite fluoride, etc. can be used. Specifically, LiFeO ₂ , LiCoO ₂ , LiNiO ₂ , LiMn ₂ O _4, and their indefinite compounds, MnO ₂ , TiS ₂ , FeS ₂ , Nb ₃ S ₄ , Mo ₃ S ₄ , CoS ₂ , V ₂ O ₅ , _{P 2 O 5, CrO 3,} V 3 O 3, TeO 2, GeO 2, LiNi 0 .33 Mn 0 .33 may be used such as Co _{0 .33} O _2.

A positive electrode conductive material can be used for the positive electrode active material layer. The conductive material for the positive electrode may be any electronic conductive material which does not cause a chemical change in the charge and discharge potential of the positive electrode active material used.

For example, graphite such as natural graphite (flax graphite), artificial graphite, carbon black such as acetylene black, Ketjen black, channel black, furnace black, lamp black, thermal black, carbon fiber, Conductive fibers such as metal fibers, metal powders such as carbon fluoride and aluminum, conductive whiskers such as zinc oxide and potassium titanate, conductive metal oxides such as titanium oxide, organic conductive materials such as polyphenylene derivatives, and the like. Single or a mixture of these can be used as the conductive material for the positive electrode.

Of these conductive materials, artificial graphite and acetylene black are particularly preferred. Although the addition amount of a electrically conductive material is not specifically limited, 1-50 mass% is preferable with respect to a positive electrode active material material, and 1-30 mass% is especially preferable. As carbon and graphite, 2-15 mass% is especially preferable.

There is no restriction | limiting in particular as an organic substance which has the binder and thickening effect used for formation of a positive electrode active material layer, Any of a thermoplastic resin and a thermosetting resin may be sufficient. Examples include polyethylene, polypropylene, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), styrenebutadiene rubber, tetrafluoroethylene-hexafluoroethylene copolymer, tetrafluoroethylene- Perfluoroalkylvinylether copolymer (PFA), vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-chlorotrifluoroethylene copolymer, ethylene-tetrafluoroethylene copolymer (ETFE resin), Polychlorotrifluoroethylene (PCTFE), vinylidene fluoride-pentafluoropropylene copolymer, propylene-tetrafluoroethylene copolymer, ethylene-chlorotrifluoroethylene copolymer (ECTFE), vinylidene fluoride-hexa Fluoropropylene-tetrafluoroethylene copolymer, vinylidene fluoride-perfluoromethylvinylether-tetrafluoroethylene copolymer, ethyl - acrylic acid copolymer or the material (Na ⁺⁾ ion crosslinked product thereof, ethylene-methacrylic acid copolymer or of the material (Na ⁺⁾ ion crosslinked product thereof, ethylene-methyl acrylate copolymer or (Na ⁺⁾ ions of the material, A crosslinked product, an ethylene-methyl methacrylate copolymer, or a (Na ⁺ ) ion crosslinked product of the above materials, and these materials may be used alone or as a mixture.

More preferred among these materials are polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE).

In addition to the above-mentioned electrically conductive material, a positive electrode active material layer can further mix | blend a filler, a dispersing agent, an ion conductor, a pressure increasing agent, and other various additives. As the filler, any fibrous material which does not cause chemical change in the battery constructed can be used. Usually, olefin polymers, such as polypropylene and polyethylene, fiber, such as glass and carbon, are used. Although the addition amount of a filler is not specifically limited, As content in an active material layer, 0-30 mass% is preferable.

An aqueous solvent or an organic solvent is used as a dispersion medium for preparation of the positive electrode active material slurry. Although water is normally used as an aqueous solvent, Additives, such as alcohols, such as ethanol, and cyclic amides, such as N-methylpyrrolidone, can also be added to about 30 mass% or less with respect to water.

As the organic solvent, linear amides such as cyclic amides such as N-methylpyrrolidone, N, N-dimethylformamide and N, N-dimethylacetamide, anisole, toluene and xyl Aromatic hydrocarbons, such as ene, alcohol, such as butanol and cyclohexanol, Among these, cyclic amides, such as N-methylpyrrolidone, N, N- dimethylformamide, N, N- dimethylacetate Linear amides, such as an amide, are preferable.

A positive electrode active material, an organic material having a binding and thickening effect as a binder, a conductive material for a positive electrode, and other fillers, blended as necessary, are mixed with these solvents to prepare a positive electrode active material slurry, and a predetermined thickness of the positive electrode current collector is obtained. A positive electrode active material layer is formed by apply | coating.

In addition, the upper limit of the positive electrode active material concentration in this positive electrode active material slurry is 70 mass% normally, Preferably it is 55 mass%, and a minimum is 30 mass% normally, Preferably it is 40 mass%. When the concentration of the positive electrode active material exceeds this upper limit, the positive electrode active material in the positive electrode active material slurry tends to aggregate, and when the concentration of the positive electrode active material is lower than the lower limit, the positive electrode active material easily precipitates during storage of the positive electrode active material slurry.

Moreover, the upper limit of the binder concentration in the positive electrode active material slurry is 30 mass% normally, Preferably it is 10 mass%, and a minimum is 0.1 mass% normally, Preferably it is 0.5 mass%. When the concentration of the binder exceeds this upper limit, the internal resistance of the obtained positive electrode may become large, and below the lower limit, the binder property of the positive electrode active material layer may decrease.

As the current collector for positive electrode, for example, a valve metal or an alloy thereof, which forms a passivation film on the surface by anodization in an electrolyte solution, is preferably used. Examples of the valve metals include metals belonging to the periodic table group 4, 5, 13, and alloys thereof. Specifically, Al, Ti, Zr, Hf, Nb, Ta, and alloys containing these metals can be exemplified, and Al, Ti, Ta and alloys containing these metals can be preferably used. In particular, Al and its alloy are preferable because of their light weight and high energy density. Although the thickness of the collector for positive electrodes is not specifically limited, Usually, it is about 1-50 micrometers.

<Non-aqueous electrolyte solution>

As electrolyte solution used for this invention, what melt | dissolved the solute in the non-aqueous solvent can be used, for example. As the solute, an alkali metal salt, quaternary ammonium salt, or the like can be used. Specifically, 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 are preferably used. These solutes may be used in one kind or may be used by mixing two or more kinds.

The content of these solutes in the electrolyte is usually 0.2 mol / L or more, preferably 0.5 mol / L or more, and usually 2 mol / L or less, preferably 1.5 mol / L or less.

As said non-aqueous solvent, For example, Cyclic ester compounds, such as cyclic carbonates, such as ethylene carbonate, a propylene carbonate, butylene carbonate, and vinylene carbonate, (gamma) -butyrolactone; Chain ethers such as 1,2-dimethoxyethane; Cyclic ethers such as crown ether, 2-methyltetrahydrofuran, 1,2-dimethyltetrahydrofuran, 1,3-dioxolane and tetrahydrofuran; Linear carbonates such as diethyl carbonate, ethyl methyl carbonate and dimethyl carbonate; and the like can be used. Among these, nonaqueous solvents containing a cyclic carbonate and a linear carbonate are preferable.

These non-aqueous solvents may be used in one kind, or may be used by mixing two or more kinds.

The non-aqueous electrolyte solution used for this invention may contain various preparations, such as a cyclic carbonate which has an unsaturated bond in a molecule | numerator, a conventionally well-known overcharge inhibitor, a deoxidizer, and a dehydrating agent.

As a cyclic carbonate which has an unsaturated bond in the said molecule | numerator, a vinylene carbonate type compound, a vinyl ethylene carbonate type compound, a methylene ethylene carbonate type compound, etc. are mentioned, for example.

Examples of the vinylene carbonate-based compound include vinylene carbonate, methyl vinylene carbonate, ethyl vinylene carbonate, 4,5-dimethyl vinylene carbonate, 4,5-diethyl vinylene carbonate, and fluorovinylene. Carbonate, trifluoromethylvinylene carbonate, and the like.

As said vinyl ethylene carbonate type compound, vinyl ethylene carbonate, 4-methyl-4- vinyl ethylene carbonate, 4-ethyl-4- vinyl ethylene carbonate, 4-n-propyl-4- vinyl ethylene carbonate, 5- Methyl-4-vinyl ethylene carbonate, 4, 4- divinyl ethylene carbonate, 4, 5- divinyl ethylene carbonate, etc. are mentioned.

As said methylene ethylene carbonate type compound, methylene ethylene carbonate, 4, 4- dimethyl- 5-methylene ethylene carbonate, 4, 4- diethyl-5- methylene ethylene carbonate, etc. are mentioned, for example.

Among these, vinylene carbonate and vinyl ethylene carbonate are preferable, and vinylene carbonate is particularly preferable.

Moreover, a difluorophosphate like lithium difluorophosphate etc. are mentioned as a preferable example.

These may be used individually by 1 type and may use 2 or more types together.

When the non-aqueous electrolyte contains a cyclic carbonate compound having an unsaturated bond in a molecule, the ratio in the non-aqueous electrolyte is usually 0.01% by mass or more, preferably 0.1% by mass or more, particularly preferably 0.3% by mass or more, Most preferably, it is 0.5 mass% or more, Usually 8 mass% or less, Preferably it is 4 mass% or less, Especially preferably, it is 3 mass% or less.

By containing the cyclic carbonate which has an unsaturated bond in a molecule | numerator in electrolyte solution, the cycling characteristics of a battery can be improved. Although the reason is not clear, it is presumed that a stable protective film can be formed on the surface of the cathode. However, when the content is small, the characteristic does not fully improve. However, when there is too much content, there exists a tendency for the amount of gas generation at the time of high temperature storage to increase, and it is preferable to make content in a non-aqueous electrolyte solution into the said range.

Examples of the overcharge inhibitor include aromatics such as biphenyl, alkylbiphenyl, terphenyl, and partial hydrogenated products of cyclophenyl, cyclohexylbenzene, t-butylbenzene, t-amylbenzene, diphenylether and dibenzofuran. compound; Partial fluorides of the above aromatic compounds such as 2-fluorobiphenyl, o-cyclohexylfluorobenzene, and p-cyclohexylfluorobenzene; Fluorine anisole compounds, such as 2, 4- difluoro anisole, 2, 5- difluoro anisole, and 2, 6- difluoro anisole, etc. are mentioned.

These may be used individually by 1 type and may use two or more types together.

The overcharge inhibitor ratio in a non-aqueous electrolyte solution is 0.1-5 mass% normally. By incorporating an overcharge preventing agent, it is possible to suppress rupture and ignition of the non-aqueous secondary battery in the case of overcharge or the like.

As another preparation, For example, Carbonate compounds, such as a fluoroethylene carbonate, a trifluoropropylene carbonate, a phenylethylene carbonate, an erythrita carbonate, a spirobis- dimethyl carbonate, a methoxyethyl- methyl carbonate; Succinic anhydride, glutaric anhydride, maleic anhydride, citraconic anhydride, glutaconic anhydride, itaconic anhydride, diglycolic anhydride, cyclohexanedicarboxylic anhydride, cyclopentanetetracarboxylic dianhydride, and phenyl succinic anhydride Carboxylic anhydrides of; Ethylene sulfide, 1,3-propanesultone, 1,4-butanesultone, methyl methanesulfonate, busulfan, sulfolane, sulfolene, dimethyl sulfone and tetramethylthiuram monosulfide, N, N-di Sulfur-containing compounds such as methylmethanesulfonamide and N, N-diethylmethanesulfonamide; 1-methyl-2-pyrrolidinone, 1-methyl-2-piperidone, 3-methyl-2-oxazolidinone, 1,3-dimethyl-2-imidazolidinone and N-methylsuccinimide, etc. Nitrogen-containing compound; Hydrocarbon compounds such as heptane, octane and cycloheptane; fluorine-containing aromatic compounds such as fluorobenzene, difluorobenzene, hexafluorobenzene, and benzotrifluoride.

These may be used individually by 1 type and may use two or more types together.

The ratio of these preparations in non-aqueous electrolyte solution is 0.1-5 mass% normally. By containing these preparations, capacity retention characteristics and cycle characteristics after high temperature storage of a battery can be improved.

The non-aqueous electrolyte solution may contain an organic polymer compound in the electrolyte solution, and may be a gel, rubber, or solid sheet solid electrolyte. In this case, specific examples of the organic polymer compound include polyether polymer compounds such as polyethylene oxide and polypropylene oxide; Crosslinked polymers of polyether polymer compounds; Vinyl alcohol-based polymer compounds such as polyvinyl alcohol and polyvinyl butyral; Insoluble compounds of vinyl alcohol-based high molecular compounds; Polyepichlorohydrin; Polyphosphazenes; Polysiloxanes; Vinyl polymer compounds such as polyvinylpyrrolidone, polyvinylidene carbonate, and polyacrylonitrile; Polymer copolymers such as poly (ω-methoxy oligooxyethylene methacrylate-co-methyl methacrylate); and the like can be given.

<Separator>

As long as the separator used in the non-aqueous secondary battery of the present invention has a predetermined mechanical strength to electrically insulate between the positive electrodes, has a high ion permeability, and combines resistance to oxidation on the side contacting the positive electrode and reducing on the negative electrode side, It is not particularly limited.

Resin, an inorganic substance, glass fiber, etc. are used as a material of the separator which has such a required characteristic.

As the resin, an olefin polymer, a fluorine polymer, a cellulose polymer, polyimide, nylon, or the like is used. Specifically, it is preferable to select from a material that is stable with respect to the electrolyte solution and excellent in liquid retention property, and it is preferable to use a porous sheet or a nonwoven fabric made of polyolefin such as polyethylene or polypropylene as a raw material.

As the inorganic substance, oxides such as alumina and silicon dioxide, nitrides such as aluminum nitride and silicon nitride, sulfates such as barium sulfate and calcium sulfate are used, and particulate or fibrous ones are used.

As the form, a thin film such as a nonwoven fabric, a woven fabric, or a microporous film is used. As a thin film shape, the thing of 0.01-1 micrometer of pore diameters and 5-50 micrometers in thickness is used preferably. In addition to the above independent thin film shape, a separator formed by forming a composite porous layer containing the inorganic particles in at least one surface layer of the positive electrode and the negative electrode using a binder made of resin can be used. For example, forming a porous layer using a fluorine resin as a binder on the alumina particle whose 90% particle diameter is less than 1 micrometer on both surfaces of an anode is mentioned.

The non-aqueous electrolyte used in the present invention is effective in reducing the reaction resistance related to the deintercalation of lithium ions into the electrode active material, which is considered to be a factor capable of realizing good low-temperature discharge characteristics. However, it has been found that in a battery having a large direct current resistance, the direct current resistance is inhibited and the effect of reducing the reaction resistance cannot be 100% reflected in the low temperature discharge characteristics. By using a battery having a small DC resistance component, this can be improved to sufficiently exhibit the effect of the non-aqueous electrolyte.

<Exterior case>

The outer case is not particularly limited as long as it is a substance that is stable with respect to the non-aqueous electrolyte solution used. Specifically, metals such as nickel plated steel sheets, stainless steel, aluminum or aluminum alloys, magnesium alloys, or laminated films (laminate films) of resins and aluminum foils are used. In light of weight reduction, a metal or laminated film of aluminum or an aluminum alloy is preferably used.

Examples of the outer case using the metals include those in which the metals are welded to each other by laser welding, resistance welding, and ultrasonic welding to form an enclosed sealing structure, or those having a caulking structure using the metals via a resin gasket. Can be.

As an exterior case using the said laminated film, what is made into a sealed sealing structure by heat-sealing resin layers, etc. are mentioned. In order to improve sealing property, you may interpose the resin different from resin used for a laminated film between the said resin layers. In particular, when the resin layer is thermally fused through a current collecting terminal to form a sealed structure, the metal and the resin are bonded to each other. Thus, a resin having a polar group or a modified resin having a polar group introduced therein is preferably used.

<Protection element>

A protective element which is a component of the non-aqueous secondary battery of the present invention described above. A valve (current blocking valve) etc. which cut off the electric current which flows through a circuit by the rapid rise of may be mentioned.

It is preferable to select one of the conditions which do not operate in normal use of a high current as said protection element, and from a viewpoint of high output, it is more preferable to set it as the design which does not reach abnormal heat generation or thermal runaway even without the protection element which protects a battery. .

Example

Hereinafter, although an Example and a comparative example are given and this invention is demonstrated further more concretely, this invention is not limited to these Examples, unless the summary is exceeded.

In addition, the various characteristics of the graphite used by the following example and the comparative example are shown in following Table 1. These graphites were prepared based on the methods described herein and known methods.

Example 1

Spherical natural graphite (A) was used as the graphite particles, and the decomposition-based petroleum heavy oil obtained at the time of naphtha thermal decomposition was mixed with a low crystalline carbon precursor, and heat treatment was performed at 1300 ° C. in an inert gas. The obtained fired material was ground and classified to obtain negative electrode material 1. In the obtained multilayer structure carbon material powder, the amount of deposition of amorphous carbon was 2.6 mass%.

Example 2

A negative electrode material 2 was obtained in the same manner as in Example 1, except that the amount of amorphous carbon deposited was 1.4 mass%.

Example 3

A negative electrode material 3 was obtained in the same manner as in Example 1, except that the amount of amorphous carbon deposited was 0.6% by mass.

Example 4

A negative electrode material 4 was obtained in the same manner as in Example 1 except that spherical natural graphite (B) was used as the graphite particles and the amount of deposition of amorphous carbon was 2.7 mass%.

Example 5

A negative electrode material 5 was obtained in the same manner as in Example 4 except that the amount of amorphous carbon adhered to 1.9% by mass.

Example 6

A negative electrode material 6 was obtained in the same manner as in Example 1 except that spherical natural graphite (C) was used as the graphite particles, and the amount of deposition of amorphous carbon was 2.4 mass%.

Example 7

A negative electrode material 7 was obtained in the same manner as in Example 6, except that the amount of amorphous carbon deposited was 1.2% by mass.

Comparative Example 1

A negative electrode material 8 was obtained in the same manner as in Example 4, except that the amount of amorphous carbon deposited was 4.4% by mass.

Comparative Example 2

A negative electrode material 9 was obtained in the same manner as in Example 1 except that spherical natural graphite (D) was used as the graphite particles, and the amount of deposition of amorphous carbon was set to 12% by mass.

Comparative Example 3

A negative electrode material 10 was obtained in the same manner as in Example 1 except that spherical natural graphite (E) was used as the graphite particles, and the amount of deposition of amorphous carbon was 3.9 mass%.

[Comparative Example 4]

A negative electrode material 11 was obtained in the same manner as in Example 1 except that spherical natural graphite (F) was used as the graphite particles, and the amount of deposition of amorphous carbon was set to 1.8% by mass.

[Comparative Example 5]

A negative electrode material 12 was obtained in the same manner as in Example 1 except that flake natural graphite (G) was used as the graphite particles, and the amount of deposition of amorphous carbon was 2.7 mass%.

Comparative Example 6

A negative electrode material 13 was obtained in the same manner as in Example 1 except that flake natural graphite (H) was used as the graphite particles and the amount of deposition of amorphous carbon was 1.9 mass%.

Comparative Example 7

Spherical natural graphite (B) was used as the negative electrode material 14 as it is.

[Production of Non-aqueous Secondary Battery]

<Production of a cathode sheet>

Using the negative electrode material prepared in Examples and Comparative Examples as the negative electrode material, a negative electrode active material layer having a negative electrode active material layer density of 1.60 ± 0.03 g / cm ³ was produced. Specifically, 20.00 ± 0.02g (0.200g in terms of solid content) of 1 mass% carboxymethylcellulose sodium salt aqueous solution to 20.00 ± 0.02g of negative electrode material, and the weight average molecular weight 270,000 styrene butadiene rubber aqueous dispersion 0.50 ± 0.05 g (0.2 g in terms of solid content) was added, stirred for 5 minutes with a hybrid mixer manufactured by Keyence, and degassed for 30 seconds to obtain a slurry.

This slurry was applied on a copper foil having a thickness of 18 µm as a current collector, with a width of 5 cm using a doctor blade so that the negative electrode material was attached in an amount of 12.0 ± 0.3 mg / cm ² , and air dried at room temperature. Furthermore, after drying at 110 degreeC for 30 minutes, it roll-pressed using the roller of diameter 20cm, and adjusted so that the density of the negative electrode active material layer might be 1.60 +/- 0.03g / cm <^3> , and obtained the electrode sheet.

<Production of non-aqueous secondary battery (2016 coin type battery)>

The negative electrode sheet produced by the above method was punched into a disk shape having a diameter of 12.5 mm, and the lithium metal foil was punched into a disk shape having a diameter of 14 mm to make a counter electrode. Between the two electrodes, a separator (porous polyethylene film product) impregnated with an electrolyte solution in which LiPF ₆ was dissolved to 1 mol / L in a mixed solvent of ethylene carbonate and ethyl methyl carbonate (volume ratio = 3: 7) was placed. Each battery was produced.

[evaluation]

<Plate Plate Strength>

The negative electrode sheet produced by the above method was cut to a width of 20 mm, attached to the test SUS plate with double-sided tape (attached the active material layer side to the double-sided tape side), and fixed in the horizontal direction, and the end portion of the negative electrode sheet was sandwiched by a universal testing machine. Put on. In this state, the negative electrode sheet fixing part of the universal testing machine was lowered in the vertical direction, and the negative electrode sheet was pulled off at a 90 degree angle from the double-sided tape. At this time, the average value of the load applied between the negative electrode sheet and the double-sided tape was measured, and the value divided by the negative electrode sheet sample width (20 mm) was used as the electrode plate strength value (mN / mm).

Initial irreversible capacity, initial efficiency

Using the said non-aqueous secondary battery (2016 coin type battery), the initial irreversible capacity | capacitance and initial efficiency at the time of battery charge / discharge were measured by the following measuring method.

Charge the lithium counter electrode to 5mV at a current density of 0.16mA / cm ² , and charge at a constant voltage of 5mV until the charge capacity reaches 350mAh / g to dope lithium into the cathode, then 0.33mA / cm ² It discharged to 1.5V with respect to the lithium counter electrode by the current density of.

Subsequently, the second and third were charged at 10 mV and 0.005 C cut by cc-cv charging at the same current density, and the discharge was discharged to 1.5 V at 0.04 C in the total number of tests. The sum of the difference between the charge capacity and the discharge capacity of these three cycles was calculated as the initial irreversible capacity. In addition, the discharge capacity of this material was made into the discharge capacity of the 3rd cycle, and discharge capacity / (discharge capacity of the 3rd cycle + initial irreversible capacity) of the 3rd cycle was made into initial stage efficiency.

As a result of the above measurement, the linear pressure (kg / 5cm) required for rolling so that the density of the negative electrode active material layer was 1.6 g / cm ³ and the particle size (d50, d50,) of the negative electrode materials 1-14 of Examples 1-7 and Comparative Examples 1-7 d90, d10), circularity, rolling load (P), specific surface area and tap density are shown in Table 2 below.

Although this invention was detailed also demonstrated with reference to the specific embodiment, it is clear for those skilled in the art that various changes and correction can be added without deviating from the mind and range of this invention. This application is based on the JP Patent application (patent application 2012-039013) of an application on February 24, 2012, The content is integrated in this specification with reference.

Claims (11)

delete delete delete delete A multilayer structure carbon material for a non-aqueous secondary battery, wherein at least a part of the surface of the graphite particles is coated with amorphous carbon and satisfies the following conditions (1) to (4):
(1) The average particle diameter d50 of the said multilayer structure carbon material is 19.1 micrometers or more and 31 micrometers or less
(2) The circularity of the said multilayer structure carbon material is 0.88 or more
(3) Amount of adhesion of the amorphous carbon in the multilayer structure carbon material is 0.01% by mass or more and 2.7% by mass or less
(4) The ratio (P / d50) of rolling load P defined below and d50 of the said multilayer structure carbon material is 30 or less:
P = (Current collector using a multilayer structure carbon material, comprising a 1% by mass of carboxymethyl cellulose sodium salt and 1% by mass of styrene-butadiene rubber as a binder relative to the multilayer structure carbon material Linear pressure (kg / 5cm) required to prepare a negative electrode active material layer deposited in an amount of 12.0 mg / cm ² above, and to roll the density of the negative electrode active material layer to 1.6 g / cm ³ )
(5) The specific surface area of the said multilayer structure carbon material measured by the BET method is 4.5 m <^2> / g or less. The method according to claim 5,
The multilayer structure carbon material for non-aqueous secondary batteries whose tap density of the said multilayer structure carbon material for non-aqueous secondary batteries is 0.8 g / cm <^3> or more and 1.30 g / cm <^3> or less. The method according to claim 5,
A multilayer structure carbon material for nonaqueous secondary batteries, wherein the specific surface area of the multilayer structure carbon material for nonaqueous secondary batteries is 0.2 m ² / g or more and 4.5 m ² / g or less. The method according to claim 5,
The multilayer structure carbon material for non-aqueous secondary batteries whose Raman R value of the said graphite particle is 0.1 or more and 0.6 or less. A negative electrode for nonaqueous secondary batteries comprising a current collector and a multilayer structure carbon material layer formed on the current collector, wherein the multilayer structure carbon material layer is a multilayer structure for nonaqueous secondary batteries according to any one of claims 5 to 8. A negative electrode for a non-aqueous secondary battery containing a carbon material. A non-aqueous secondary battery comprising a positive electrode and a negative electrode capable of occluding and releasing lithium ions, and a non-aqueous electrolyte, wherein the negative electrode is a negative electrode for a non-aqueous secondary battery according to claim 9. delete