JP2022095866A - Anode material for nonaqueous secondary battery, anode for nonaqueous secondary battery, and nonaqueous secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an anode material for a nonaqueous secondary battery that has a high capacity and is excellent in initial efficiency and cycle characteristic, and an anode for a nonaqueous secondary battery and a nonaqueous secondary battery using the same.

SOLUTION: A carbon material for an anode of a nonaqueous secondary battery includes composite carbon particles (A) and silicon oxide particles (B) (but excluding composite particles including at least silicon oxide particles and graphite particles), where the composite carbon particle (A) includes at least graphite particles, carbonaceous matter, and carbonaceous particles. It is preferable that the carbonaceous particles in the composite carbon particles (A) are at least one selected from the group consisting of coal powder, vapor phase carbon powder, carbon black, Ketjen black, and carbon nanofiber.

SELECTED DRAWING: None

COPYRIGHT: (C)2022,JPO&INPIT

Description

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

In recent years, with the miniaturization of electronic devices, the demand for high-capacity secondary batteries has been increasing. In particular, non-aqueous secondary batteries having a higher energy density and excellent rapid charge / discharge characteristics than nickel-cadmium batteries and nickel-hydrogen batteries, particularly lithium-ion secondary batteries, are attracting attention. In particular, a non-aqueous lithium secondary battery consisting of a positive electrode and a negative electrode capable of storing and releasing lithium ions and a non-aqueous electrolytic solution in which lithium salts such as LiPF ₆ and LiBF ₄ are dissolved has been developed and put into practical use.

Various negative electrode materials have been proposed for this non-aqueous lithium secondary battery, but since they have high capacity and excellent flatness of discharge potential, they can be graphitized with natural graphite or coke. Graphitized carbonaceous particles such as the obtained artificial graphite, graphitized mesophase pitch, and graphitized carbon fiber are used. In addition, an amorphous carbon material is also used because it is relatively stable with respect to some electrolytic solutions. Furthermore, the surface of the graphite particles is coated or adhered with amorphous carbon, and the graphite has a high capacity and a small irreversible capacity, and the amorphous carbon has excellent stability with an electrolytic solution. Carbon materials with combined properties are also used.

On the other hand, for the purpose of further increasing the capacity of the lithium ion secondary battery, studies have been made on using a silicon oxide material in combination with these carbon materials. As a combination of a carbonaceous material and a silicon oxide material, Patent Document 1 describes a carbonaceous particle using a carbonic particle having a carbon layer on at least a part of the surface of the graphite particle. Therefore, Patent Document 2 describes a mixture of spherical graphite and scaly graphite as carbonaceous particles.

Japanese Unexamined Patent Publication No. 2013-200983 Japanese Unexamined Patent Publication No. 2013-200984

According to the studies by the present inventors, it has been found that the negative electrode materials of Patent Document 1 and Patent Document 2 have problems such as insufficient initial efficiency and cycle characteristics.
That is, the subject of the present invention is a negative electrode material for a non-aqueous secondary battery having a high capacity and excellent initial efficiency, cycle characteristics, etc., and a negative electrode for a non-aqueous secondary battery and a non-aqueous secondary battery using the negative electrode material. To provide.

As a result of diligent studies by the present inventors to solve the above problems, it has been found that the above problems can be solved by using a negative electrode material for a non-aqueous secondary battery containing silicon oxide particles and specific carbonaceous particles. rice field.
That is, the gist of the present invention is as follows.

[1] Contains composite carbon particles (A) and silicon oxide particles (B) (excluding composite particles containing at least silicon oxide particles and graphitic particles), and the composite carbon particles (A) are at least graphitic. A carbon material for the negative electrode of a non-aqueous secondary battery containing particles, carbonaceous material, and carbonaceous particles.

[2] The carbonaceous particles in the composite carbon particles (A) are at least one selected from the group consisting of coal fine particles, vapor phase carbon powder, carbon black, Ketjen black and carbon nanofibers, according to [1]. Non-aqueous secondary battery Negative carbon material.

[3] The carbon material for a negative electrode of a non-aqueous secondary battery according to [1] or [2], wherein the primary particle diameter or fiber diameter of the carbonaceous particles in the composite carbon particles (A) is 1 nm or more and 500 nm or less.

[4] The negative electrode material for a non-aqueous secondary battery according to any one of [1] to [3], wherein the composite carbon particles (A) contain spherical graphite.

[5] The negative electrode material for a non-aqueous secondary battery according to any one of [1] to [4], wherein the average particle diameter (d50) of the silicon oxide particles (B) is 0.01 μm or more and 20 μm or less.

[6] The non-aqueous battery according to any one of [1] to [5], wherein the particle diameter (d10) of the 10% integrating portion from the small particle side of the silicon oxide particles (B) is 0.001 μm or more and 6 μm or less. Negative electrode material for next battery.

[7] Average particle size ratio of silicon oxide particles (B) and composite carbon particles (A) (R = [average particle size of silicon oxide particles (B) (d50)] / [average particles of composite carbon particles (A)] The negative electrode material for a non-aqueous secondary battery according to any one of [1] to [6], wherein the diameter (d50)]) is 0.001 or more and 10 or less.

[8] The ratio ( _MO / M _Si ) of the number of _oxygen atoms (MO) to the number of silicon atoms (M _Si ) in the silicon oxide particles (B) is 0.5 to 1.6, [1] to [ 7] The negative electrode material for a non-aqueous secondary battery according to any one of.

[9] The carbon material for a negative electrode of a non-aqueous secondary battery according to any one of [1] to [8], wherein the silicon oxide particles (B) contain zero-valent silicon atoms.

[10] The negative electrode material for a non-aqueous secondary battery according to [9], which contains silicon microcrystals in the silicon oxide particles (B).

[11] A negative electrode for a non-aqueous secondary battery including a current collector and an active material layer formed on the current collector, wherein the active material layer is one of [1] to [10]. A negative electrode for a non-aqueous secondary battery, which comprises the above-described negative electrode material for a non-aqueous secondary battery.

[12] A non-aqueous secondary battery including a positive electrode, a negative electrode, and an electrolyte, wherein the negative electrode is the negative electrode for the non-aqueous secondary battery according to [11].

According to the present invention, a negative electrode material for a non-aqueous secondary battery having a high capacity and excellent initial efficiency, cycle characteristics, etc., and a negative electrode for a non-aqueous secondary battery and a non-aqueous secondary battery using the negative electrode material are provided. To.

Hereinafter, the present invention will be described in detail, but the present invention is not limited to the following description, and can be arbitrarily modified and carried out without departing from the gist of the present invention. In the present invention, when a numerical value or a physical property value is inserted before and after using "-", it is used as including the values before and after that.

[Negative electrode material]
The carbon material for the negative electrode of the non-aqueous secondary battery of the present invention (hereinafter, may be referred to as “negative electrode material of the present invention”) is the composite carbon particles (A) (hereinafter, “composite carbon particles of the present invention (hereinafter, the composite carbon particles of the present invention). A) ”and silicon oxide particles (B) (hereinafter, may be referred to as“ silicon oxide particles (B) of the present invention ”) (However, at least silicon oxide particles and graphite particles. The composite carbon particles (A) include at least a graphite particle, a carbonaceous substance, and a carbonaceous particle.

[mechanism]
<Action and effect based on the inclusion of composite carbon particles (A)>
Since the composite carbon particles (A) containing at least the graphite particles, the carbonaceous material, and the carbonaceous particles have minute irregularities of the carbonaceous particles, the inclusion of the composite carbon particles (A) makes the electrolytic solution finer. It is considered that the flow path is secured and the input / output characteristics at low temperature are improved.

<Action and effect based on the inclusion of silicon oxide particles (B)>
By containing the high-capacity silicon oxide particles (B), it is possible to obtain a high-capacity negative electrode material.
In particular, the ratio ( _MO / M _Si ) of the number of _oxygen atoms (MO) to the number of silicon atoms (M _Si ) in the silicon oxide particles (B) is 0.5 to 1.6, so that the capacity is high. At the same time, the amount of volume change due to the storage and release of Li ions is small and close to the amount of volume change of the composite carbon particles (A), reducing the performance deterioration due to impaired contact with the composite carbon particles (A). It becomes possible.
Further, since the silicon oxide particles (B) contain zero-valent silicon atoms, the range of potential for storing and releasing Li ions becomes close to that of the composite carbon particles (A), and the volume changes due to the storage and release of Li ions. Is generated at the same time as the composite carbon particles (A), so that the interface between the composite carbon particles (A) and the silicon oxide particles (B) is less likely to be displaced, and the contact with the composite carbon particles (A) is impaired, resulting in performance deterioration. Can be reduced.

<Action and effect of blending composite carbon particles (A) and silicon oxide particles (B)>
Due to the presence of the composite carbon particles (A) between the particles of the silicon oxide particles (B), the fine irregularities of the composite carbon particles (A) ensure a fine flow path of the electrolytic solution and silicon oxide. It is possible to increase the number of contacts with the particles (B), increase the adhesive strength between the particles, improve the plate strength, and cut the conductive path due to large expansion and contraction during charging and discharging of the silicon oxide particles (B). It is thought that it can be suppressed. Therefore, it is considered that a carbon material for the negative electrode of a non-aqueous secondary battery having a high capacity and excellent initial efficiency and cycle characteristics could be obtained.

The negative electrode material of the present invention contains specific composite carbon particles (A) and silicon oxide particles (B), but the silicon oxide particles (B) are composite particles containing at least silicon oxide particles and graphite particles. Except when it exists as.

<Composite carbon particles (A)>
<Structure>
The composite carbon particle (A) of the present invention is a composite particle containing at least a graphitic particle, a carbonaceous substance, and a carbonaceous particle. By containing carbonaceous particles, uniform and continuous fine flow paths are formed on the surface of the composite carbon particles (A), and smooth movement of lithium ions is possible even at low temperatures, so that non-aqueous secondary is possible. It is possible to improve the input / output characteristics of the battery at low temperatures.

<Physical characteristics>
(Particle size)
The average particle size (d50) of the composite carbon particles (A) of the present invention is usually 50 μm or less, preferably 40 μm or less, more preferably 30 μm or less, still more preferably 20 μm or less, and usually 3 μm or more, preferably 6 μm or more. More preferably, it is 8 μm or more. If the d50 of the composite carbon particles (A) is too small, the specific surface area becomes large, so that the decomposition of the electrolytic solution increases and the initial efficiency tends to decrease. If the d50 is too large, the rapid charge / discharge characteristics tend to deteriorate. be.

In the present invention, the "average particle diameter (d50)" of the composite carbon particles (A) of the present invention, the silicon oxide particles (B) of the present invention described later, the graphite particles, the negative electrode material of the present invention, etc. is the volume. The particle size (d50) of the 50% volume integration section from the small particle side measured based on the reference particle size distribution, and "d10" is the particle size of the 10% volume integration section from the small particle side. “D90” is the particle size of the 90% volume integration unit from the small particle side. These are measured by the methods described in the Examples section below.

The ratio R of the d50 of the silicon oxide particles (B) of the present invention described later to the d50 of the composite carbon particles (A) of the present invention = [average particle diameter (d50) of the silicon oxide particles (B)] / [composite carbon particles]. The average particle size of (A)] (d50) is preferably 0.001 or more and 10 or less. When the average particle size ratio R is within the above range, the silicon oxide particles (B) can be present in the gaps between the composite carbon particles (A), and the theoretical capacity is larger than that of the composite carbon particles (A). Due to the presence of the silicon particles (B), further increase in capacity can be realized. The volume change of the silicon oxide particles (B) due to the occlusion / release of alkaline ions such as Li ions due to charging / discharging is absorbed by the gap formed by the composite carbon particles (A), so that the volume of the silicon oxide particles (B) is absorbed. It is possible to suppress the disconnection of the conductive path due to the change, and as a result, it is possible to realize improvement of cycle characteristics, rapid charge / discharge characteristics, and high capacity. The average particle size ratio R is more preferably 0.01 to 3, still more preferably 0.1 to 1, particularly preferably 0.15 to 0.8, and most preferably 0.2 to 0. It is 7.

The particle size (d10) of the 10% volume integration portion from the small particle side in the volume-based particle size distribution of the composite carbon particles (A) is usually 1 μm or more, preferably 3 μm or more, more preferably 5 μm or more, and usually. It is 50 μm or less, preferably 30 μm or less, and more preferably 20 μm or less.
If d10 is too small, the tendency of particle aggregation becomes strong, process inconveniences such as an increase in slurry viscosity occur, and the electrode strength and initial charge / discharge efficiency in a non-aqueous secondary battery tend to decrease. If d10 is too large, the high current density charge / discharge characteristics tend to deteriorate and the low temperature input / output characteristics tend to deteriorate.

The particle size (d90) of the 90% volume integration portion from the small particle side in the volume-based particle size distribution of the composite carbon particle (A) of the present invention is usually 5 μm or more, preferably 10 μm or more, more preferably 15 μm or more. Further, it is usually 100 μm or less, preferably 50 μm or less, and more preferably 40 μm or less.
If d90 is too small, the electrode strength in non-aqueous secondary batteries may decrease and the initial charge / discharge efficiency may decrease. It may lead to deterioration of discharge characteristics and low temperature input / output characteristics.

(BET specific surface area (SA))
The specific surface area of the composite carbon particles (A) of the present invention according to the BET method is usually 0.5 m ² / g or more, preferably 1 m ² / g or more, more preferably 2 m ² / g or more, still more preferably 3 m ² / g or more. Is. Further, it is usually 15 m ² / g or less, preferably 12 m ² / g or less, more preferably 10 m ² / g or less, still more preferably 8 m ² / g or less, and particularly preferably 6 m ² / g or less. If the specific surface area is too large, the reactivity between the portion exposed to the electrolytic solution and the electrolytic solution increases when used as the negative electrode active material, which tends to cause a decrease in initial efficiency and an increase in the amount of gas generated, making it difficult to obtain a preferable battery. Tend. If the specific surface area is too small, there are few sites where lithium ions enter and exit, and the high-speed charge / discharge characteristics and output characteristics tend to be inferior.
The specific surface area of the composite carbon particles (A) is measured by the method described in the section of Examples below.

(Tap density)
The tap density of the composite carbon particles (A) of the present invention is usually preferably 0.8 g / cm ³ or more, 0.85 g / cm ³ or more, more preferably 0.9 g / cm ³ or more, and 0.95 g / cm ³ or more. The above is more preferable. In addition, usually 1.8 g / cm ³ or less, 1.5 g / cm ³ or less is preferable, and 1.3 g / cm ³ or less is more preferable.
The fact that the tap density is 0.8 g / cm ³ or more is one of the indicators indicating that the composite carbon particles (A) have a spherical shape. The fact that the tap density is smaller than 0.8 g / cm ³ is one of the indicators that the graphitic particles, which are the raw materials of the composite carbon particles (A), are not sufficiently spherical particles. When the tap density is smaller than 0.8 g / cm ³ , sufficient continuous voids are not secured in the electrode, and the mobility of Li ions in the electrolytic solution held in the voids is lowered, so that the rapid charge / discharge characteristics are deteriorated. Tend to do.

In the present invention, the tap density is a sieve having a mesh size of 300 μm in a cylindrical tap cell having a diameter of 1.6 cm and a volume capacity of 20 cm ³ using a powder density measuring instrument Tap Densor KYT-3000 (manufactured by Seishin Co., Ltd.). After the sample is dropped through the cell to fill the cell fully, tapping with a stroke length of 10 mm is performed 1000 times, and the density obtained from the volume at that time and the weight of the sample is defined as the tap density.

(aspect ratio)
The aspect ratio of the composite carbon particles (A) of the present invention is usually 1 or more, preferably 1.5 or more, more preferably 1.6 or more, still more preferably 1.7 or more, usually 4 or less, preferably 3 or less. It is more preferably 2.5 or less, still more preferably 2 or less.
If the aspect ratio is too large, the particles tend to line up in the direction parallel to the current collecting pair when the electrode is used, so that continuous voids in the thickness direction of the electrode are not sufficiently secured, and Li ion mobility in the thickness direction is not sufficiently secured. Tends to decrease, leading to a decrease in rapid charge / discharge characteristics. The aspect ratio of the composite carbon particles (A) is A / when the diameter A is the longest of the composite carbon particles (A) when observed three-dimensionally and the diameter B is the shortest of the diameters orthogonal to the diameter A. It is represented by B. The composite carbon particles (A) are observed with a scanning electron microscope capable of magnified observation. Arbitrary 50 composite carbon particles (A) fixed to the end face of a metal having a thickness of 50 microns or less are selected, and the stage on which the sample is fixed is rotated and tilted for each, and A and B are measured. Find the average value of A / B.

(Circularity)
The composite carbon particles (A) of the present invention preferably have a circularity of 0.88 or more obtained by flow-type particle image analysis measured by the method described in the section of Examples described later. By using the composite carbon particles (A) having a high circularity as described above, the high current density charge / discharge characteristics can be enhanced.

The method for improving the circularity of the composite carbon particles (A) is not particularly limited, but a sphere-shaped composite carbon particle (A) is preferable because the shape of the interparticle voids when formed into an electrode body is adjusted. Examples of the spheroidizing treatment method include a method of mechanically approaching a spherical shape by applying a shearing force or a compressive force, and a mechanical / physical treatment method of granulating a plurality of fine particles by the adhesive force of the binder or the particles themselves. Can be mentioned.

The circularity of the composite carbon particles (A) is preferably 0.9 or more, and particularly preferably 0.92 or more. Further, it is usually 1 or less, preferably 0.98 or less, and more preferably 0.95 or less. If the circularity is too small, the high current density charge / discharge characteristics tend to deteriorate. On the other hand, if the circularity is too high, the composite carbon particles (A) become spherical, so that the contact area between the composite carbon particles (A) decreases, and the cycle characteristics of the lithium ion secondary battery obtained by using the composite carbon particles (A) may deteriorate. be.
The specific surface area by the BET method is measured by the method described in the section of Examples described later.

<Surface spacing (d002) and crystallite size (Lc) of 002 planes>
In the composite carbon particles (A) of the present invention, the surface spacing d value (interlayer distance (d002)) of the lattice planes (002 planes) determined by X-ray wide-angle diffraction by the Gakushin method is preferably 0.338 nm or less. More preferably, it is 0.337 or less. If the d002 value is too large, it means that the crystallinity of the composite carbon particles (A) is low, and the initial irreversible capacity of the lithium ion secondary battery may increase. On the other hand, since the theoretical value of the plane spacing of the 002 planes of the composite carbon particles (A) is 0.335 nm, it is usually 0.335 nm or more.

The crystallite size (Lc) of the composite carbon particles (A) of the present invention determined by X-ray wide-angle diffraction by the Gakushin method is usually in the range of 1.5 nm or more, preferably 3.0 nm or more. Below this range, the particles have low crystallinity, and the reversible capacity of the lithium ion secondary battery may decrease. The lower limit is the theoretical value of graphite.
The measuring methods of (d002) and (Lc) are as follows.

<d002 plane spacing, Lc>
The material is a mixture of sample powder and X-ray standard high-purity silicon powder, which is about 15% by weight of the total amount, and the CuKα ray monochromated with a graphite monochromator is used as the radiation source. Measure the line diffraction curve. The interplanar spacing (d002) and crystallite size (Lc) are determined using the Gakushin method.

(Raman R value)
The Raman R value is the intensity ratio R (R =) when the intensity IA of the peak PA near 1580 cm ^{-1 and the intensity IB of the peak PB near 1360 cm -1 in} the Raman spectrum obtained by Raman spectroscopy are measured. Defined as IB / IA). The term "near 1580 cm ^-1 " refers to the range of 1580 to 1620 cm ^-1 , and the term "near 1360 cm ^-1 " refers to the range of 1350 to 1370 cm ^-1 .

The Raman R value of the composite carbon particles (A) of the present invention is usually 0.01 or more, preferably 0.1 or more, more preferably 0.3 or more, still more preferably 0.36 or more, and particularly preferably 0. 4 or more, most preferably 0.5 or more. Further, it is usually 1.00 or less, preferably 0.8 or less, more preferably 0.75 or less, still more preferably 0.7 or less, and most preferably 0.65 or less.

If the Raman R value is too small, it means that the particle surface is not sufficiently damaged in the mechanical energy treatment of the graphite particles or the like in the manufacturing process of the composite carbon particles (A) of the present invention. In the composite carbon particles (A), since the amount of places where Li ions are received or released such as fine cracks and defects on the surface of graphite particles due to damage and structural defects is small, Li is used in the lithium ion secondary battery. The rapid charge / discharge property of ions may deteriorate.

Further, a large Raman R value means that, for example, the amount of amorphous carbon covering the graphite particles is large, and / or the surface fineness of the graphite particles or the like due to excessive mechanical energy treatment is performed. It indicates that the amount of cracks, defects, and structural defects is too large. If the Raman R value is too large, the influence of the irreversible capacity of amorphous carbon increases, and the side reaction with the electrolytic solution increases, resulting in lithium ions. The initial charge / discharge efficiency of the secondary battery is lowered and the amount of gas generated is increased, so that the battery capacity tends to be lowered.

The Raman spectrum can be measured with a Raman spectroscope. Specifically, the particles to be measured are naturally dropped into the measurement cell to fill the sample, and while irradiating the measurement cell with argon ion laser light, the measurement cell is rotated in a plane perpendicular to the laser light. Make a measurement.
Wavelength of argon ion laser light: 514.5 nm
Laser power on sample: 25 mW
Resolution: 4 cm ^-1
Measurement range: 1100 cm ^-1 to 1730 cm ^-1
Peak intensity measurement, peak half width measurement: background processing, smoothing processing (convolution 5 points by simple average)

(Pore volume)
The pore volume in the range of 10 nm to 100,000 nm according to the mercury intrusion method of the composite carbon particles (A) of the present invention is usually 1.0 mL / g or less, preferably 0.9 mL / g or less, more preferably 0.8 mL / g. It is g or less, and is usually 0.05 mL / g or more, preferably 0.1 mL / g or more, and more preferably 0.15 mL / g or more. When the total pore volume is less than the above range, the number of voids in which the non-aqueous electrolyte solution can enter tends to decrease, and Li ions cannot be inserted and removed in time when rapid charging and discharging are performed. The characteristics tend to deteriorate. On the other hand, if it exceeds the above range, the binder is likely to be absorbed into the voids when the electrode plate is manufactured, and the strength of the electrode plate tends to decrease accordingly.

The fine pore volume in the pore diameter range of 80 nm to 900 nm of the composite carbon particles (A) of the present invention is a value measured by a mercury injection method (mercury porosometry), and is usually 0.08 mL / g or more, preferably 0.08 mL / g or more. It is 0.1 mL / g or more, more preferably 0.15 mL / g or more, still more preferably 0.3 mL / g or more. Further, it is usually 1 mL / g or less, preferably 0.8 mL / g or less, and more preferably 0.5 mL / g or less.

When the fine pore volume in the pore diameter range of 80 nm to 900 nm is less than the above range, the electrolytic solution does not move smoothly sufficiently during charging / discharging of the non-aqueous secondary battery, and Li ions are generated during rapid charging / discharging. Insertion and desorption cannot be made in time, and lithium metal tends to precipitate and cycle characteristics tend to deteriorate. On the other hand, if it exceeds the above range, the binder is likely to be absorbed into the voids during the production of the electrode plate, which tends to cause a decrease in the plate strength and a decrease in the initial efficiency.

The method for measuring the pore volume by the mercury intrusion method is as follows.

As the device for the mercury porosimeter, a mercury porosimeter (Autopore 9520: manufactured by Micromeritics) can be used. The sample is weighed to a value of about 0.2 g, sealed in a powder cell, degassed at room temperature under vacuum (50 μmHg or less) for 10 minutes, and pretreatment is performed.
Subsequently, the pressure is reduced to 4 psia (about 28 kPa), mercury is introduced into the cell, the pressure is stepped up from 4 psia (about 28 kPa) to 40,000 psia (about 280 MPa), and then the pressure is lowered to 25 psia (about 170 kPa).

The number of steps at the time of pressurization is 80 points or more, and in each step, the amount of mercury injection is measured after an equilibrium time of 10 seconds. From the mercury intrusion curve thus obtained, the pore distribution is calculated using the Washburn formula.
The surface tension (γ) of mercury is calculated as 485 dyne / cm, and the contact angle (ψ) is calculated as 140 °. The average pore diameter is defined as the pore diameter when the cumulative pore volume is 50%.

<Manufacturing method of composite carbon particles (A)>
The method for producing the composite carbon particles (A) of the present invention is not particularly limited as long as it is a composite particle of graphite particles, carbonaceous particles and a carbonaceous substance, but for example, the following viewpoints (1) and (2) It is preferable to adopt a manufacturing method in consideration of.

(1) A mixed powder in which graphitic particles and carbonaceous particles are mixed is prepared, a carbonaceous substance precursor is mixed therein, and this is heat-treated in an inert gas.

By adopting such a manufacturing method, a multi-layer structure in which a part or the entire surface of the composite carbon particles (A), which is a preferable form of the composite carbon particles (A) of the present invention, is coated with the carbonaceous particles and the carbonaceous material. There is an advantage that it becomes easy to produce a carbon material.

(2) As a device for mixing graphite particles and carbonaceous particles, not only a mixing and stirring mechanism for mixing and stirring graphite particles and carbonaceous particles, but also a crushing mechanism for crushing graphite particles and carbonaceous particles is provided. A device provided, a so-called crushing mixer, is adopted for mixing.

By mixing the graphite particles and the carbonaceous particles using such a crushing mixer, the graphite particles and the agglomerates of the carbonic particles can be crushed and uniformly mixed. By sufficiently crushing the aggregates of graphite particles and carbonaceous particles and mixing them uniformly before compounding, it is possible to suppress the aggregation of carbonaceous particles generated in the subsequent steps. For example, in the composite carbon particles (A) in which a large amount of agglomerates of carbonaceous particles remain, the ratio of the total pore volume and the Raman R value by the micro Raman spectroscope tends to be large, and the storage characteristics tend to be deteriorated. ..

Examples of the manufacturing method in consideration of the above viewpoints (1) and (2) include manufacturing methods including the following steps (a) to (c).
Step (a): Mixing and stirring the graphite particles and carbonaceous particles while crushing them Step (b): Step of mixing the carbonaceous material precursor with the powder obtained in step (a): A step of heat-treating the mixture obtained in the step (b) in an inert gas. One type of each of the graphite particles, the carbonaceous particles and the carbonaceous material precursor may be used alone, or a combination of two or more types may be used. May be used.

<Step (a)>
The method of mixing and stirring the graphite particles and the carbonaceous particles while crushing them can be carried out by a conventional method. An example is shown below.

(1) Mixing ratio of graphite particles and carbonaceous particles The mixing ratio of graphite particles and carbonaceous particles should be appropriately selected based on the composition of the target composite particles, but with respect to the graphite particles. The carbonic particles are usually 0.01% by weight or more, preferably 0.1% by weight or more, more preferably 0.15% by weight or more, usually 20% by weight or less, preferably 10% by weight or less, and more. It is preferably 5% by weight or less, more preferably 2.9% by weight or less. Within the above range, there is an advantage that the input / output characteristics are improved even at a low temperature while satisfying various characteristics required for a lithium ion secondary battery such as battery charge / discharge efficiency and discharge capacity.

(2) Mixing device When a crushing mixer is used as a device for mixing graphite particles and carbonaceous particles, the specific device is not particularly limited, and a commercially available device can be appropriately used. For example, a locking mixer, a radige mixer, a Henschel mixer and the like can be mentioned. Further, the crushing and mixing conditions are not particularly limited, but the rotation speed of the crushing blade (chopper) is usually 100 rpm or more, preferably 1000 rpm or more, more preferably 2000 rpm or more, usually 100,000 rpm or less, preferably 30,000 rpm or less, preferably 30,000 rpm or less. Is 10000 rpm or less. Further, the crushing and mixing time is usually 30 seconds or more, preferably 1 minute or more, more preferably 10 minutes or more, and usually 24 hours or less, preferably 3 hours or less, more preferably 1 hour or less. Within the above range, aggregation of graphitic particles and carbonaceous particles can be effectively prevented.

<Step (b)>
The powder obtained in the step (a) (hereinafter, may be referred to as “raw material carbon material”) and the carbonaceous material precursor can be mixed by a conventional method. An example is shown below.

(1) Mixing temperature The mixing temperature is above the softening point of the carbonaceous material precursor, usually 5 ° C. or higher, preferably 40 ° C. or higher, more preferably 50 ° C. or higher, while usually 250 ° C. or lower, preferably 200 ° C. or lower. , More preferably 180 ° C. or lower, still more preferably 150 ° C. or lower. When mixed at a temperature lower than the softening point, the fluidity of the carbonaceous precursor deteriorates, which not only makes it impossible to mix uniformly, but also tends to cause liquid leakage during the pressure treatment. On the other hand, if the temperature is too high, it becomes difficult to uniformly mix or knead the mixture, and the heating time until the liquid is liquefied and the handling at a high temperature are required, so that the productivity tends to be poor.

(2) Mixing ratio of powder and carbonaceous material precursor obtained in step (a) The mixing ratio of powder and carbonaceous material precursor obtained in step (a) is the target composite carbon particles (A). Although it should be appropriately selected based on the composition of the above, the carbonaceous material precursor is usually 0.01% by weight or more, preferably 0.1% by weight or more, more preferably 0. 5% by weight or more, more preferably 1% by weight or more, usually 60% by weight or less, preferably 30% by weight or less, more preferably 20% by weight or less, still more preferably 10% by weight or less. Particularly preferably, it is 5% by weight or less. Within the above range, there is an advantage that the charge / discharge efficiency of the battery, the discharge capacity, and the input / output characteristics at low temperature are improved.

Further, the carbonaceous material precursor may be diluted with an organic solvent when mixed with the powder obtained in the step (a). The reason for the dilution is that by diluting with an organic solvent, the viscosity of the carbonaceous material precursor to be mixed can be lowered, and the raw material carbon material can be coated more efficiently and uniformly.

Examples of the organic solvent used here include hydrocarbons such as pentane, hexane, isohexane, heptane, octane, isooctane, decane, dimethylbutane, cyclohexane and methylcyclohexane; ethyl ether, isopropyl ether, diisoamyl ether and methylphenyl ether. Ethers such as amylphenyl ether and ethyl benzyl ether; ketones such as acetone, methyl acetone, methyl ethyl ketone, methyl isobutyl ketone and diethyl ketone; methyl formate, ethyl formate, isobutyl formate, methyl acetate, isoamyl acetate, methoxybutyl acetate, cyclohexyl acetate, etc. Esters such as methyl butyrate, ethyl butyrate, butyl benzoate, isoamyl benzoate, etc .; benzene, toluene, xylene, ethylbenzene, diethylbenzene, isopropylbenzene, amylbenzene, diamylbenzene, triamylbenzene, tetraamylbenzene, dodecylbenzene, didodecyl There are, but are not limited to, aromatic hydrocarbons such as benzene, amyltoluene, tetraline and cyclohexylbenzene. Further, two or more kinds of these may be mixed. Among these, benzene, toluene, and xylene are organic solvents having a relatively high boiling point and a low viscosity, and are particularly preferable in that the concentration change due to volatilization is unlikely to occur and the viscosity of the carbonaceous substance precursor can be lowered.

The dilution ratio with the organic solvent is such that the carbonaceous substance precursor is usually 5% by weight or more, preferably 25% by weight or more, more preferably 40% by weight or more, still more preferably 50% by weight, based on the weight of the organic solvent. It is usually 90% by weight or less, preferably 80% by weight or less, more preferably 70% by weight or less, still more preferably 60% by weight or less. If this dilution ratio is too large, the concentration of the carbonaceous material precursor decreases, and there is a tendency that the raw material carbon material cannot be efficiently coated. If the dilution ratio is too small, the concentration of the carbonaceous precursor does not decrease sufficiently, and there is a tendency that the raw material carbon material cannot be efficiently coated.

Mixing is usually carried out under normal pressure, but can also be carried out under reduced pressure or pressure if desired. Mixing can be performed by either a batch method or a continuous method. In either case, the mixing efficiency can be improved by using a combination of an apparatus suitable for crude mixing and an apparatus suitable for precise mixing.

The viscosity of the mixture or diluted mixture obtained in this step is usually 100 cP or less, preferably 70 cP or less, and more preferably 50 cP or less. Further, it is usually 1 cP or more, preferably 10 cP or more. If the viscosity is too high, deterioration during cycling tends to occur, and the cycle characteristics tend to deteriorate.

(3) Mixing device As a batch type mixing device, a mixer with a structure in which two frame molds rotate and revolve; a single piece such as a dissolver which is a high-speed high shear mixer and a butterfly mixer for high viscosity. A device with a structure in which the brate stirs and disperses in the tank; a so-called kneader-type device having a structure in which a stirring blade such as a sigma type rotates along the side surface of a semi-cylindrical mixing tank; the stirring blade has three axes. Trimix type device; A so-called bead mill type device having a rotating disk and a dispersion medium in the container is used.

It also has a container with a paddle rotated by a shaft, the inner wall of the container being formed substantially along the outermost line of rotation of the paddle, preferably in a long twin-body shape, with the paddles facing each other. Devices with a structure in which a large number of pairs are arranged in the axial direction of the shaft so as to be slidable (for example, KRC reactor manufactured by Kurimoto Iron Works, SC processor, TEM manufactured by Toshiba Machine Co., Ltd., TEX-K manufactured by Japan Steel Works, Ltd.) Etc.); Furthermore, it has a single internal shaft and a container in which a plurality of plow-shaped or serrated paddles fixed to the shaft are arranged in different phases, and the inner wall surface thereof is the outermost line of rotation of the paddle. A (external heat type) device having a structure preferably formed in a cylindrical shape (for example, a Ladyge mixer manufactured by Ladyge Co., a flow shear mixer manufactured by Taiheiyo Kiko Co., Ltd., and a DT manufactured by Tsukishima Machine Co., Ltd.). A dryer or the like) can also be used. To perform mixing in a continuous manner, a pipeline mixer, a continuous bead mill, or the like may be used.

Further, the mixing conditions are not particularly limited, but the rotation speed of the rotary blade is usually 5 rpm or more, preferably 10 rpm or more, more preferably 50 rpm or more, still more preferably 100 rpm, particularly preferably 150 rpm, and usually 100,000 rpm or less, preferably 100,000 rpm or less. Is 10000 rpm or less, more preferably 1000 rpm or less, still more preferably 500 rpm or less, and particularly preferably 200 rpm or less. The mixing time is usually 30 seconds or more, preferably 1 minute or more, more preferably 10 minutes or more, and usually 24 hours or less, preferably 3 hours or less, more preferably 1 hour or less. Within the above range, the raw material carbon material can be uniformly coated with the carbonaceous material precursor.

<Step (c)>
(1) Firing temperature The calcination temperature varies depending on the carbonaceous material precursor used to prepare the mixture, but when carbonizing, it is usually heated to 600 ° C. or higher, preferably 700 ° C. or higher, more preferably 800 ° C. or higher, and is usually used. It is preferably kept at 1500 ° C. or lower, preferably 1400 ° C. or lower, and more preferably 1200 ° C. or lower.

In the case of graphitization, it is usually heated to 2500 ° C. or higher, preferably 2700 ° C. or higher, more preferably 2900 ° C. or higher. The upper limit of the heating temperature is usually 3500 ° C. or lower, preferably 3200 ° C. or lower, and more preferably 3100 ° C. or lower.
In the firing treatment conditions, the heat history temperature condition, the temperature rising rate, the cooling rate, the heat treatment time, and the like are appropriately set. Further, after heat treatment in a relatively low temperature region, the temperature can be raised to a predetermined temperature. The reactor used in this step may be a batch type, a continuous type, a single reactor, or a plurality of reactors.

(2) Furnace used for firing The furnace used for firing is not particularly limited as long as the above requirements are satisfied. A heat treatment tank), a Tanman furnace, an Achison furnace, a high frequency induction heating furnace, or the like can be used, and as the heating method, direct resistance heating, indirect resistance heating, direct combustion heating, radiant heat heating, and the like can be used. At the time of heat treatment, stirring may be performed if necessary.

<Other processes>
The composite particles obtained by the above-mentioned production method may be separately pulverized.
Examples of the coarse crusher used for the crushing process include a jaw crusher, an impact type crusher, a cone crusher and the like, examples of the intermediate crusher include a roll crusher and a hammer mill, and examples of the fine crusher include a ball mill and vibration. Examples include mills, pin mills, stirring mills, jet mills and the like.

Among these, ball mills, vibration mills and the like have a short crushing time and are preferable from the viewpoint of processing speed.

The crushing speed is appropriately set depending on the type and size of the apparatus. For example, in the case of a ball mill, it is usually 50 rpm or more, preferably 100 rpm or more, more preferably 150 rpm or more, still more preferably 200 rpm or more. Further, it is usually 2500 rpm or less, preferably 2300 rpm or less, and more preferably 2000 rpm or less. If the speed is too fast, it tends to be difficult to control the particle size, and if the speed is too slow, the processing speed tends to be slow.
The crushing time is usually 30 seconds or longer, preferably 1 minute or longer, more preferably 1 minute 30 seconds or longer, still more preferably 2 minutes or longer. Further, it is usually 3 hours or less, preferably 2.5 hours or less, and more preferably 2 hours or less. If the crushing time is too short, it tends to be difficult to control the particle size, and if the crushing time is too long, the productivity tends to decrease.

In the case of a vibration mill, the crushing speed is usually 50 rpm or more, preferably 100 rpm or more, more preferably 150 rpm or more, still more preferably 200 rpm or more. Further, it is usually 2500 rpm or less, preferably 2300 rpm or less, and more preferably 2000 rpm or less. If the speed is too fast, it tends to be difficult to control the particle size, and if the speed is too slow, the processing speed tends to be slow.
The crushing time is usually 30 seconds or longer, preferably 1 minute or longer, more preferably 1 minute 30 seconds or longer, still more preferably 2 minutes or longer. Further, it is usually 3 hours or less, preferably 2.5 hours or less, and more preferably 2 hours or less. If the crushing time is too short, it tends to be difficult to control the particle size, and if the crushing time is too long, the productivity tends to decrease.

Further, the composite particles obtained by the above-mentioned production method may be subjected to a particle size classification treatment.

As the classification treatment condition, the opening is usually 53 μm or less, preferably 45 μm or less, and more preferably 38 μm or less.
The device used for the classification process is not particularly limited, but for example, in the case of dry sieving: rotary sieving, swaying sieving, rotary sieving, vibration sieving, etc. can be used, and in the case of dry air flow sieving. : Gravity type classifier, inertial force type classifier, centrifugal force type classifier (classifier, cyclone, etc.) can be used, and in the case of wet sieving: mechanical wet classifier, hydraulic classifier, settling classifier, A centrifugal wet classifier or the like can be used.

(Content of carbonaceous material)
The content of the carbonaceous substance in the composite carbon particles (A) of the present invention is usually 0.01% by weight or more, preferably 0.1% by weight or more, more preferably 0.3% or more, based on the graphite particles. Particularly preferably, it is 0.7% by weight or more, and the content is usually 20% by weight or less, preferably 15% by weight or less, still more preferably 10% by weight or less, particularly preferably 7% by weight or less, and most preferably. It is 5% by weight or less.

If the content of carbonaceous material is too high, the composite carbon particles (A) will be damaged and the material will be destroyed when rolling is performed at a pressure sufficient to achieve a high capacity in a non-aqueous secondary battery. Initial cycle charge / discharge irreversible There is a tendency to increase the reverse capacity and decrease the initial efficiency.
On the other hand, if the content of the carbonaceous material is too small, it tends to be difficult to obtain the effect of the coating. That is, the side reaction with the electrolytic solution cannot be sufficiently suppressed in the battery, which tends to increase the charge / discharge irreversible capacity during the initial cycle and decrease the initial efficiency.

The content of carbonaceous material can be calculated from the sample weight before and after firing the material. At this time, it is calculated assuming that there is no change in weight of the graphitic particles before and after firing.
Assuming that w1 is the weight (kg) of the graphitic particles and w2 is the weight (kg) of the composite carbon particles (A) after firing, the content of the carbonaceous material is calculated by the following formula.
Carbon content (% by weight) = [(w2-w1) / w1] × 100

(Content of carbonaceous particles)
The content of the carbonaceous particles in the composite carbon particles (A) of the present invention is the content of the carbonic particles with respect to the graphite particles, and is usually 0.01% by weight or more, preferably 0.1% by weight or more, more preferably 0.1% by weight or more. 0.3% or more, particularly preferably 0.7% by weight or more, and usually 20% by weight or less, preferably 15% by weight or less, still more preferably 10% by weight or less, particularly preferably 7% by weight or less, most. It is preferably 5% by weight or less.

If the content of carbonaceous particles is too high, the reactivity with the electrolytic solution tends to increase, and the cycle characteristics of the battery tend to deteriorate.
On the other hand, if the content of carbonaceous particles is too small, it tends to be difficult to obtain the effect of coating. That is, the side reaction with the electrolytic solution cannot be sufficiently suppressed in the battery, which tends to increase the charge / discharge irreversible capacity during the initial cycle and decrease the initial efficiency.

Here, the content of the carbonaceous particles is the amount added when the carbonaceous particles are mixed.

<Graphitic particles>
As the graphitic particles used as the raw material of the composite carbon particles (A) of the present invention, either natural graphite or artificial graphite may be used. The graphite is preferably one having few impurities, and is used after being subjected to various purification treatments as necessary.
The shape of graphite is not particularly limited and can be appropriately selected from flaky, fibrous, amorphous particles and the like, but is preferably flaky.

Examples of the natural graphite include scaly graphite, scaly graphite, soil graphite and the like. The scaly graphite is mainly produced in Sri Lanka, the scaly graphite is produced in Madagascar, China, Brazil, Ukraine, Canada, etc., and the soil graphite is mainly produced in the Korean Peninsula, China, Mexico, etc. Is.
Among these natural graphites, soil graphite generally has a small particle size and low purity. On the other hand, scaly graphite and scaly graphite have advantages such as a high degree of graphitization and a low amount of impurities, and thus can be preferably used in the present invention.

Examples of the artificial graphite include graphite particles such as coke, needle coke, and high-density carbon material produced by heat-treating a pitch raw material at a high temperature.
Specific examples of artificial graphite include coal tar pitch, coal-based heavy oil, atmospheric residual oil, petroleum-based heavy oil, aromatic hydrocarbons, nitrogen-containing cyclic compounds, sulfur-containing cyclic compounds, polyphenylene, and polyvinyl chloride. Organic substances such as polyvinyl alcohol, polyacrylonitrile, polyvinyl butyral, natural polymers, polyphenylene silfide, polyphenylene oxide, furfuryl alcohol resin, phenol-formaldehyde resin, and imide resin are usually used at a temperature in the range of 2500 ° C or higher and 3200 ° C or lower. Examples thereof include those that have been fired and graphitized.

As the graphite particles, as described above, natural graphite, artificial graphite, coke powder, needle coke powder, graphitized powder such as resin, and the like can be used. Of these, natural graphite is preferable in terms of high discharge capacity and ease of production.

As the graphitic particles used as the raw material of the composite carbon particles (A) of the present invention, it is preferable to use sphericalized natural graphite for the reason that the electrode plate structure can be easily controlled.
In order to obtain spherical graphite particles, for example, a method of performing a spheroidizing treatment on graphite as a raw material can be mentioned. The method for performing the spheroidizing process will be described below, but the method is not limited to this method.

As the device used for the spheroidizing process, for example, a device that repeatedly applies mechanical actions such as compression, friction, and shear force to the particles, including the interaction between the particles of the carbon material, can be used mainly by the impact force. ..
Specifically, it has a rotor with a large number of blades installed inside the casing, and by rotating the rotor at high speed, mechanical actions such as impact compression, friction, and shear force are applied to the carbon material introduced inside. Is preferable, and an apparatus for performing surface treatment is preferable. Further, it is preferable that the graphite has a mechanism for repeatedly giving a mechanical action by circulating graphite.

Preferred devices for imparting mechanical action to carbon materials include, for example, a hybridization system (manufactured by Nara Kikai Seisakusho), Cryptron (manufactured by EarthTechnica Co., Ltd.), CF mill (manufactured by Ube Kosan Co., Ltd.), and a mechanofusion system (manufactured by Hosokawa Micron). (Made), Theta Composer (manufactured by Tokuju Kosakusho Co., Ltd.), etc. Among these, the hybridization system manufactured by Nara Machinery Co., Ltd. is preferable.

When processing using the above device, for example, the peripheral speed of the rotating rotor is usually 30 to 100 m / sec, preferably 40 to 100 m / sec, and more preferably 50 to 100 m / sec. Further, the treatment of giving a mechanical action to the carbon material can be performed by simply passing graphite through the apparatus, but it is preferable to circulate or retain the graphite in the apparatus for 30 seconds or longer, and to treat the graphite in the apparatus for 1 minute or longer. Is more preferably treated by circulating or accumulating.

(Physical characteristics of graphitic particles)
The graphitic particles in the present invention preferably satisfy any one or more of the following physical characteristics. In the present invention, one kind of graphite particles exhibiting such physical characteristics may be used alone, or two or more kinds may be used in combination in any combination.
The following method for measuring the physical properties is the same as the method for measuring the composite carbon particles (A) of the present invention.

(A) Average particle diameter d50
The d50 of the graphitic particles is usually 50 μm or less, preferably 40 μm or less, more preferably 30 μm or less, still more preferably 20 μm or less, particularly preferably 15 μm or less, usually 3 μm or more, preferably 4 μm or more, more preferably 5 μm, and further. It is preferably 6 μm μm or more. If d50 is too small, the specific surface area becomes large, so that the decomposition of the electrolytic solution increases, and the initial efficiency tends to decrease. If d50 is too large, the rapid charge / discharge characteristics tend to deteriorate.

(B) Aspect ratio The aspect ratio of the graphitic particles is usually 1 or more, preferably 1.5 or more, more preferably 1.6 or more, still more preferably 1.7 or more, usually 4 or less, preferably 3 or less, and more. It is preferably 2.5 or less, more preferably 2 or less.
If the aspect ratio is too large, the particles tend to line up in the direction parallel to the current collecting pair when the electrode is used, so that continuous voids in the thickness direction of the electrode are not sufficiently secured, and lithium ion mobility in the thickness direction is not sufficiently secured. Tends to decrease, leading to a decrease in rapid charge / discharge characteristics.

(C) d10
The d10 of the graphitic particles is usually 1 μm or more, preferably 2 μm or more, more preferably 3 μm or more, and usually 20 μm or less, preferably 15 μm or less, more preferably 10 μm or less.
If d10 is too small, the tendency of particle aggregation becomes strong, process inconveniences such as an increase in slurry viscosity occur, the electrode strength in a non-aqueous secondary battery tends to decrease, and the initial charge / discharge efficiency tends to decrease. If d10 is too large, the high current density charge / discharge characteristics tend to deteriorate and the low temperature input / output characteristics tend to deteriorate.

(D) d90
The d90 of the graphitic particles is usually 5 μm or more, preferably 8 μm or more, more preferably 10 μm or more, and usually 100 μm or less, preferably 50 μm or less, more preferably 30 μm or less, still more preferably 25 μm or less.
If d90 is too small, the electrode strength in non-aqueous secondary batteries may decrease and the initial charge / discharge efficiency may decrease. It may lead to deterioration of discharge characteristics and low temperature input / output characteristics.

(E) BET specific surface area (SA)
The specific surface area of the graphitic particles by the BET method is usually 0.5 m ² / g or more, preferably 1 m ² / g or more, more preferably 3 m ² / g or more, still more preferably 4 m ² / g or more, and particularly preferably 5 m ² / G or more. Further, it is usually 30 m ² / g or less, preferably 20 m ² / g or less, more preferably 10 m ² / g or less, still more preferably 9 m ² / g or less, and particularly preferably 8 m ² / g or less. If the specific surface area is too large, the reactivity between the portion exposed to the electrolytic solution and the electrolytic solution increases when used as the negative electrode active material, which tends to cause a decrease in initial efficiency and an increase in the amount of gas generated, making it difficult to obtain a preferable battery. Tend. If the specific surface area is too small, there are few sites where lithium ions enter and exit, and the high-speed charge / discharge characteristics and output characteristics tend to be inferior.

(F) Tap Density The tap density of the graphite particles is usually preferably 0.8 g / cm ³ or more, 0.85 g / cm ³ or more, more preferably 0.9 g / cm ³ or more, and 0.95 g / cm ³ or more. Is more preferable. In addition, usually 1.8 g / cm ³ or less, 1.5 g / cm ³ or less is preferable, and 1.3 g / cm ³ or less is more preferable.
The fact that the tap density is 0.8 g / cm ³ or more is one of the indicators indicating that the graphitic particles are spherical. When the tap density is smaller than 0.8 g / cm ³ , sufficient continuous voids are not secured in the electrode, and the mobility of lithium ions in the electrolytic solution held in the voids is lowered, so that the rapid charge / discharge characteristics are deteriorated. Tend to do.

(G) Circularity The circularity of the graphitic particles is usually 0.88 or more, more preferably 0.9 or more, still more preferably 0.92 or more. The circularity is usually 1 or less, preferably 0.99 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 deteriorate.

(H) Raman R value The Raman R value of the graphite particles is usually 1 or less, preferably 0.8 or less, more preferably 0.6 or less, still more preferably 0.5 or less, and usually 0.05 or more, preferably 0.05 or less. Is 0.1 or more, more preferably 0.2 or more, still more preferably 0.25 or more. When the Raman R value is lower than this range, the crystallinity of the particle surface becomes too high, the number of Li insertion sites decreases, and the rapid charge / discharge characteristics tend to deteriorate. On the other hand, if it exceeds this range, the crystallinity of the particle surface is disturbed, the reactivity with the electrolytic solution increases, and the charge / discharge efficiency tends to decrease and the gas generation tends to increase.

(I) Pore volume The pore volume in the range of 10 nm to 100,000 nm by the mercury intrusion method of graphite particles is usually 1.0 mL / g or less, preferably 0.9 mL / g or less, and more preferably 0.8 mL / g. It is g or less, and is usually 0.05 mL / g or more, preferably 0.1 mL / g or more, and more preferably 0.15 mL / g or more. When the total pore volume is less than the above range, the number of voids in which the non-aqueous electrolyte solution can enter tends to decrease, and Li ions cannot be inserted and removed in time when rapid charging and discharging are performed. The characteristics tend to deteriorate. On the other hand, if it exceeds the above range, the binder is likely to be absorbed into the voids when the electrode plate is manufactured, and the strength of the electrode plate tends to decrease accordingly.

(J) Micropore volume in the pore diameter range of 80 nm to 900 nm The micropore volume in the pore diameter range of 80 nm to 900 nm of the graphite particles is a value measured by a mercury intrusion method (mercury porosometry) and is usually 0. It is .08 mL / g or more, preferably 0.1 mL / g or more, more preferably 0.15 mL / g or more, still more preferably 0.3 mL / g or more. Further, it is usually 1 mL / g or less, preferably 0.8 mL / g or less, and more preferably 0.5 mL / g or less.
When the fine pore volume in the pore diameter range of 80 nm to 900 nm is less than the above range, the electrolytic solution does not move smoothly sufficiently during charging / discharging of the non-aqueous secondary battery, and Li ions are generated during rapid charging / discharging. Insertion and desorption cannot be made in time, and lithium metal tends to precipitate and cycle characteristics tend to deteriorate. On the other hand, if it exceeds the above range, the binder is likely to be absorbed into the voids during the production of the electrode plate, which tends to cause a decrease in the plate strength and a decrease in the initial efficiency.

<Carbonaceous particles>
The type of carbonaceous particles used as the material constituting the composite carbon particles (A) of the present invention is not particularly limited, but one of coal fine powder, vapor phase carbon powder, carbon black, Ketjen black, carbon nanofiber and the like. Or two or more kinds can be mentioned. Of these, carbon black is particularly preferable. Carbon black has the advantage that the input / output characteristics are high even at low temperatures, and at the same time, it can be obtained inexpensively and easily.

Further, the shape is not particularly limited, and may be any of granular, spherical, chain, needle-like, fibrous, plate-like, scale-like and the like.

(Physical characteristics of carbonaceous particles)
The carbonaceous particles in the present invention preferably satisfy any one or more of the following physical characteristics. In the present invention, one kind of carbonaceous particles exhibiting such physical characteristics may be used alone, or two or more kinds may be used in combination in any combination.

(A) Primary particle diameter or fiber diameter The primary particle diameter or fiber diameter of the carbonaceous particles in the present invention is usually 1 nm or more and 500 nm or less. The primary particle size is preferably 3 nm or more, more preferably 15 nm or more, further preferably 30 nm or more, particularly preferably 40 nm or more, preferably 200 nm or less, more preferably 100 nm or less, and particularly preferably 70 nm or less. Is. The primary particle diameter or fiber diameter of the carbonaceous particles can be measured by electron microscope observation such as SEM or a laser diffraction type particle size distribution meter.
If the primary particle diameter or fiber diameter of the carbonaceous particles is too large, the specific surface area tends to be small, and the input / output characteristics at low temperatures tend to deteriorate. Also, if the primary particle size or fiber diameter of the carbonaceous particles is too small, the specific surface area tends to increase and the capacity tends to decrease.

(B) BET specific surface area (SA)
The specific surface area of the carbonaceous particles by the BET method is usually 1 m ² / g or more, preferably 10 m ² / g or more, more preferably 30 m ² / g or more, and usually 1000 m ² / g or less, preferably 500 m ² / g. Hereinafter, the range is more preferably 100 m ² / g or less, still more preferably 70 m ² / g or less. If the specific surface area is too large, the reactivity between the portion exposed to the electrolytic solution and the electrolytic solution increases when used as the negative electrode active material, which tends to cause a decrease in initial efficiency and an increase in the amount of gas generated, making it difficult to obtain a preferable battery. Tend. If the specific surface area is too small, there are few sites where Li ions enter and exit, and the high-speed charge / discharge characteristics and output characteristics tend to be inferior.

(C) Bulk Density The bulk density of the carbonaceous particles is usually 0.01 g / cm ³ or more, preferably 0.1 g / cm ³ or more, more preferably 0.15 g / cm ³ or more, and further preferably 0. It is 17 g / cm ³ or more, usually 1 g / cm ³ or less, preferably 0.8 g / cm ³ or less, and more preferably 0.6 g / cm ³ or less.
If the bulk density of the carbonaceous particles is too large, the low temperature input / output characteristics tend to deteriorate. Also, if the bulk density is too small, the battery capacity tends to decrease.
For the bulk density of carbonaceous particles, use a powder density measuring instrument to drop the raw carbon material into a cylindrical tap cell with a diameter of 1.6 cm and a volume capacity of 20 cm ³ through a sieve with an opening of 300 μm to fill the cell. After filling, it can be measured by determining the density from the volume at that time and the weight of the sample.

(D) Tap Density The tap density of the carbonaceous particles is usually 0.1 g / cm ³ or more, preferably 0.15 g / cm ³ or more, more preferably 0.2 g / cm ³ or more, and usually 2 g / cm ³ or more. Hereinafter, it is preferably 1 g / cm ³ or less, and more preferably 0.8 g / cm ³ or less. If the tap density of the carbonaceous particles is too large, the low temperature input / output characteristics tend to decrease, and if it is too small, the battery capacity tends to decrease.

(E) DBP oil absorption The DBP oil absorption of carbonaceous particles is usually 10 mL / 100 g or more, preferably 50 mL / 100 g or more, more preferably 60 mL / 100 g or more, usually 1000 mL / 100 g or less, preferably 500 mL / 100 g or less, and more. It is preferably 200 mL / 100 g or less, and more preferably 100 mL / 100 g or less.
If the amount of DBP oil absorbed by the carbonaceous particles is too large, the capacity tends to decrease, and if it is too small, the low temperature input / output characteristics tend to decrease.

<Carbonate precursor>
As the carbonaceous material precursor which is the raw material of the composite carbon particles (A) of the present invention, the carbon material described in the following (i) or (ii) is preferable, and even if one of these is used alone, 2 Any combination of seeds or more may be used in combination.

(I) Coal-based heavy oil, DC-based heavy oil, decomposition-based petroleum heavy oil, aromatic hydrocarbons, N-ring compounds, S-ring compounds, polyphenylene, organic synthetic polymers, natural polymers, thermoplastic resins and Hydrocarbonable organics selected from the group consisting of thermosetting resins (ii) Hydrocarbonable organics dissolved in low molecular weight organic solvents

The coal-based heavy oil is preferably a hydrocarbon pitch from a soft pitch to a hard pitch, a dry distillate liquefied oil, or the like, and the DC heavy oil is preferably a normal pressure residual oil, a reduced pressure residual oil, or the like, and the decomposition. As the petroleum heavy oil, ethylene tar or the like produced as a by-product during thermal decomposition of crude oil, naphtha or the like is preferable, and as the aromatic hydrocarbon, acenaphthalene, decacyclene, anthracene, phenanthrene or the like is preferable, and the N-ring compound is used. , Phenazine, Acrydin and the like are preferable, the S-ring compound is preferably thiophene, bithiophene and the like, the polyphenylene is preferably biphenyl, terphenyl and the like, and the organic synthetic polymer is polyvinyl chloride, polyvinyl alcohol, etc. Polyvinyl butyral, insolubilized products of these, polyacrylonitrile, polypyrrole, polythiophene, polystyrene and the like are preferable, and as the natural polymer, polysaccharides such as cellulose, lignin, mannan, polygalactouronic acid, chitosan and saccharose are preferable. The thermoplastic resin is preferably polyphenylene sulfide, polyphenylene oxide or the like, and the thermosetting resin is preferably a furfuryl alcohol resin, a phenol-formaldehyde resin, an imide resin or the like.

Further, the carbonaceous substance precursor may be a carbide such as a solution dissolved in a low molecular weight organic solvent such as benzene, toluene, xylene, quinoline and n-hexane.

[Silicon oxide particles (B)]
<Structure>
As described in the above-mentioned mechanism section, the ratio ( _MO / M _Si ) of the number of _oxygen atoms (MO) to the number of silicon atoms (M _Si ) in the silicon oxide particles (B) of the present invention is 0.5 to 0.5. It is preferably 1.6. Further, it is preferable to contain a zero-valent silicon atom. Further, it is preferable to contain crystallized silicon microcrystals.

The _MO / M _Si is more preferably 0.7 to 1.3, and particularly preferably 0.8 to 1.2. When _MO / M _Si is in the above range, the capacity is increased as compared with the composite carbon particles (A) due to the particles made of highly active amorphous silicon oxide in which alkaline ions such as Li ions easily enter and exit. And the amorphous structure makes it possible to achieve a high cycle maintenance rate. Further, the silicon oxide particles (B) are filled in the gaps formed by the composite carbon particles (A) while ensuring contact points with the composite carbon particles (A), so that alkaline ions such as Li ions due to charge and discharge can be charged. The volume change of the silicon oxide particles (B) due to occlusion / release can be absorbed by the gap. This makes it possible to suppress the breaking of the conductive path due to the volume change of the silicon oxide particles (B).

Silicon oxide particles (B) containing zero-valent silicon atoms are usually centered around -110 ppm present in silicon oxide in solid NMR ( ²⁹ Si-DDMAS) measurements, and the peak peak is -100 to -120 ppm. In addition to the broad peak (P1) in the range of −70 ppm, it is preferable that there is a broad peak (P2) centered on −70 ppm, in which the peak peak is in the range of −65 to −85 ppm. The area ratio (P2) / (P1) of these peaks is preferably 0.1 ≦ (P2) / (P1) ≦ 1.0, and 0.2 ≦ (P2) / (P1) ≦ 0. It is more preferably in the range of 8. Since the silicon oxide particles (B) containing zero-valent silicon atoms have the above-mentioned properties, a negative electrode material having a large capacity and high cycle characteristics can be obtained.

Further, it is preferable that the silicon oxide particles (B) containing zero-valent silicon atoms generate hydrogen when an alkali hydroxide is allowed to act on the particles (B). The amount of zero-valent silicon atoms in the silicon oxide particles (B) converted from the amount of hydrogen generated at this time is preferably 2 to 45% by weight, more preferably about 5 to 36% by weight, and 10 It is more preferably about 30% by weight. If the amount of zero-valent silicon atoms is less than 2% by weight, the charge / discharge capacity may be small, and conversely, if it exceeds 45% by weight, the cycle characteristics may be inferior.

The silicon oxide particles (B) containing microcrystals of silicon preferably have the following properties.

i. In X-ray diffraction (Cu-Kα) with copper as the cathode, a diffraction peak attributed to Si (111) centered around 2θ = 28.4 ° was observed, and based on the spread of the diffraction line. The particle size of the silicon crystal determined by the Scheller's formula is preferably 1 to 500 nm, more preferably 2 to 200 nm, and further preferably 2 to 20 nm. If the size of the silicon fine particles is smaller than 1 nm, the charge / discharge capacity may be small, and conversely, if it is larger than 500 nm, the expansion / contraction during charging / discharging becomes large, and the cycle property may be deteriorated. The size of the silicon fine particles can be measured by a transmission electron micrograph.

ii. In solid-state NMR ( ²⁹ Si-DDMAS) measurements, the spectrum has a broad silicon dioxide peak centered around -110 ppm and a peak characteristic of Si diamond crystals around -84 ppm. It should be noted that this spectrum is completely different from ordinary silicon oxide (SiOx, x = 1.0 + α), and the structure itself is clearly different. In addition, a transmission electron microscope confirms that silicon crystals are dispersed in amorphous silicon dioxide.

The amount of silicon microcrystals in the silicon oxide particles (B) is preferably 2 to 45% by weight, more preferably about 5 to 36% by weight, and even more preferably about 10 to 30% by weight. If the amount of fine crystals of silicon is less than 2% by weight, the charge / discharge capacity may be small, and conversely, if it exceeds 45% by weight, the cycleability may be inferior.

<Physical characteristics>
(Particle size)
The average particle size of the silicon oxide particles (B) of the present invention, that is, the particle size (d50) of the 50% volume integration portion from the small particle side in the volume-based particle size distribution is 0.1 μm or more and 20 μm or less. preferable. If the d50 of the silicon oxide particles (B) is in the above range, the silicon oxide particles (B) are present in the gaps formed by the composite carbon particles (A) when the electrodes are used, and alkalis such as Li ions due to charging and discharging are present. The gap absorbs the volume change of the silicon oxide particles (B) due to the storage and release of ions, suppresses the conduction path breakage due to the volume change, and as a result, the cycle characteristics can be improved. The d50 of the silicon oxide particles (B) is more preferably 0.3 to 15 μm, still more preferably 0.4 to 10 μm, and particularly preferably 0.5 to 8 μm.

The d50 of the silicon oxide particles (B) of the present invention has the above-mentioned suitable R = [average particle diameter (d50) of the silicon oxide particles (B)) with respect to the d50 of the composite carbon particles (A) of the present invention. ] / [Average particle size (d50) of the composite carbon particles (A)] is preferably satisfied.

In the volume-based particle size distribution of the silicon oxide particles (B) of the present invention, the particle size (d10) of the 10% volume integration portion from the small particle side is preferably 0.001 μm or more and 6 μm or less. When d10 of the silicon oxide particles (B) is in the above range and appropriate fine powder is present, the silicon oxide particles (B) existing in the gaps between the composite carbon particles (A) can take a good conductive path. It is possible to improve the cycle characteristics and suppress the increase in the specific surface area to reduce the irreversible capacity. The d10 of the silicon oxide particles (B) is more preferably 0.01 to 4 μm, still more preferably 0.1 to 3 μm.

The particle diameter (d90) of the 90% volume integration portion from the small particle side in the volume-based particle size distribution of the silicon oxide particles (B) of the present invention is preferably 0.5 μm or more and 40 μm or less. When d90 is in the above range, the silicon oxide particles (B) are likely to exist in the gaps between the composite carbon particles (A), a good conductive path can be obtained, and the cycle characteristics are good. The d90 of the silicon oxide particles (B) is more preferably 0.8 to 30 μm, still more preferably 1 to 20 μm, and particularly preferably 1.2 to 12 μm.

(Specific surface area)
The specific surface area of the silicon oxide particles (B) of the present invention according to the BET method is preferably 80 m ² / g or less, and preferably 60 m ² / g or less. Further, it is preferably 0.5 m ² / g or more, more preferably 1 m ² / g or more, and further preferably 1.5 m ² / g or more. When the specific surface area of the silicon oxide particles (B) by the BET method is within the above range, the efficiency of input / output of alkaline ions such as Li ions can be maintained satisfactorily, and the silicon oxide particles (B) have a suitable size. , Can be present in the gap formed by the composite carbon particles (A), and a conductive path with the composite carbon particles (A) can be secured. Further, since the silicon oxide particles (B) have a suitable size, it is possible to suppress an increase in the irreversible capacity and secure a high capacity.
The specific surface area by the BET method is measured by the method described in the section of Examples described later.

<Manufacturing method of silicon oxide particles (B)>
The silicon oxide particles (B) used in the present invention are usually obtained by thermally reducing SiO ₂ using silicon dioxide (SiO ₂ ) as a raw material and metallic silicon (Si) and / or carbon. Is a general term for particles composed of silicon oxide represented by a value of 0 <x <2 (however, as described later, it is also possible to dope other elements other than silicon and carbon, in this case. Although the composition formula is different from that of SiOx, such a composition is also included in the silicon oxide particles (B) used in the present invention). Silicon (Si) has a larger theoretical capacity than graphite, and amorphous silicon oxide allows alkaline ions such as lithium ions to easily enter and exit, making it possible to obtain a high capacity. As described above, the silicon oxide particles (B) of the present invention have a ratio ( _MO / M _Si ) of the number of _oxygen atoms (MO) to the number of silicon atoms (M _Si ) of 0.5 to 1.6. It is preferably particles (B).

The silicon oxide particles (B) used in the present invention may be composite silicon oxide particles having silicon oxide particles as nuclei and having a carbon layer made of amorphous carbon on at least a part of the surface thereof. As the silicon oxide particles (B), one selected from the group consisting of silicon oxide particles (B1) having no carbon layer made of amorphous carbon and composite silicon oxide particles (B2) may be used alone. Often, two or more types may be used in combination. Here, "providing at least a part of the surface with a carbon layer made of amorphous carbon" means that the carbon layer not only covers a part or all of the surface of the silicon oxide particles in a layered manner, but also the carbon layer. It also includes a form that adheres to or adheres to a part or all of the surface. The carbon layer may be provided so as to cover the entire surface, or a part thereof may be coated or adhered / adhered.

(Manufacturing method of silicon oxide particles (B1))
The silicon oxide particles (B1) may be produced by any method as long as they satisfy the characteristics of the present invention, but for example, silicon oxide particles produced by a method as described in Japanese Patent No. 3952118 may be used. can. Specifically, silicon dioxide powder and metallic silicon powder or carbon powder are mixed at a specific ratio, the mixture is filled in a reactor, the pressure is reduced to normal pressure or a specific pressure, and the temperature rises to 1000 ° C. or higher. The silicon oxide particles represented by the general formula SiOx (x is 0.5 ≦ x ≦ 1.6) can be obtained by heating and holding to generate SiOx gas and cooling and precipitating. The precipitate can be made into particles by subjecting it to mechanical energy treatment.

For mechanical energy processing, for example, a device such as a ball mill, a vibrating ball mill, a planetary ball mill, or a rolling ball mill is used to put a raw material filled in a reactor and a moving body that does not react with the raw material, and vibrate or rotate the raw material. Alternatively, silicon oxide particles (B) satisfying the above physical properties can be formed by a method of giving a movement in which these are combined.

(Method for manufacturing composite silicon oxide particles (B2))
The method for producing composite silicon oxide particles (B2) having a carbon layer made of amorphous carbon on at least a part of the surface of the silicon oxide particles is not particularly limited, but the silicon oxide particles (B1) are made of petroleum. After mixing a system or carbon-based tar or pitch, polyvinyl alcohol, polyacrylic nitrile, phenol resin, cellulose or other resin with a solvent or the like as necessary, the temperature is 500 ° C to 3000 ° C, preferably 700 ° C in a non-oxidizing atmosphere. By firing at ~ 2000 ° C., more preferably 800-1500 ° C., composite silicon oxide particles (B2) having a carbon layer made of amorphous carbon on at least a part of the surface of the silicon oxide particles are produced. be able to.

(Disproportionation treatment)
The silicon oxide particles (B) of the present invention are obtained by further heat-treating the silicon oxide particles (B1) and the composite type silicon oxide particles (B2) produced as described above to disqualify them. It is also possible to form a structure in which zero-valent silicon atoms are unevenly distributed as Si fine crystals in the amorphous SiOx by subjecting the non-uniformization treatment, and the Si fine crystals in the amorphous SiOx are used as the negative electrode material of the present invention. As described in the section of the mechanism of, the range of the potential for storing and releasing Li ions is close to that of the carbonaceous particles, and the volume change accompanying the storage and release of Li ions occurs at the same time as the composite carbon particles (A). The relative positional relationship between the carbon particles (A) and the silicon oxide particles (B) is maintained, and it is possible to reduce the performance deterioration due to the impaired contact with the carbonaceous particles.

This disproportionation treatment can be performed by heating the above-mentioned silicon oxide particles (B1) or composite silicon oxide particles (B2) in a temperature range of 900 to 1400 ° C. in an inert gas atmosphere. ..

If the heat treatment temperature of the disproportioning treatment is lower than 900 ° C., disproportionation does not proceed at all or it takes an extremely long time to form fine cells of silicon (microcrystals of silicon), which is inefficient and conversely. If the temperature is higher than 1400 ° C., the structure of the silicon dioxide portion progresses and the traffic of Li ions is hindered, so that the function as a lithium ion secondary battery may deteriorate. The heat treatment temperature for the disproportionation treatment is preferably 1000 to 1300 ° C, more preferably 1100 to 1250 ° C. The treatment time (disproportionation time) can be appropriately controlled in the range of 10 minutes to 20 hours, particularly about 30 minutes to 12 hours depending on the disproportionation treatment temperature, but at a treatment temperature of, for example, 1100 ° C. Is preferably about 5 hours.

The disproportionation treatment may be carried out by using a reaction apparatus having a heating mechanism in an inert gas atmosphere, and is not particularly limited, and can be treated by a continuous method or a batch method, specifically, a fluidized layer reaction. A furnace, a rotary furnace, a vertical mobile layer reactor, a tunnel furnace, a batch furnace, a rotary kiln, etc. can be appropriately selected according to the purpose. In this case, as the (treatment) gas, a gas _alone or a mixed gas thereof that is inert at the above treatment temperature such as Ar, He, H2, and _N2 can be used.

(Carbon coating / Manufacture of silicon microcrystal dispersed silicon oxide particles)
The silicon oxide particles (B) of the present invention may be composite silicon oxide particles in which the surface of silicon oxide particles containing fine crystals of silicon is coated with carbon.

The method for producing such composite silicon oxide particles is not particularly limited, but for example, the following methods I to III can be preferably adopted.
I: Using silicon oxide powder represented by the general formula SiOx (0.5 ≦ x <1.6) as a raw material, an atmosphere containing at least an organic gas and / or steam at 900 to 1400 ° C, preferably 1000 to 1400 ° C. By heat treatment in a temperature range of 1050 to 1300 ° C., more preferably 1100 to 1200 ° C., the raw material silicon oxide powder is disproportionated into a composite of silicon and silicon dioxide, and the surface thereof is chemically vapor-deposited. Method II: Silicon oxide powder represented by the general formula SiOx (0.5 ≦ x <1.6) is previously subjected to 900 to 1400 ° C., preferably 1000 to 1400 ° C., more preferably 1100 to 1300 ° C. under an inert gas atmosphere. Silicon composite that is disproportionated by heat treatment in A composite obtained by sintering the dried product, or a product obtained by pulverizing silicon and its partial oxide or nitride to a particle size of preferably 0.1 to 50 μm in advance under an inert gas stream at 800 to 1400 ° C. The surface of the material heated in 1 is chemically vapor-deposited by heat treatment in an atmosphere containing at least an organic gas and / or steam in a temperature range of 800 to 1400 ° C., preferably 900 to 1300 ° C., more preferably 1000 to 1200 ° C. Method III: Silicon oxide powder represented by the general formula SiOx (0.5 ≦ x <1.6) is previously prepared in a temperature range of 500 to 1200 ° C., preferably 500 to 1000 ° C., more preferably 500 to 900 ° C. Using a material chemically vapor-deposited with an organic gas and / or steam as a raw material, heat treatment is performed in a temperature range of 900 to 1400 ° C., preferably 1000 to 1400 ° C., more preferably 1100 to 1300 ° C. under an inert gas atmosphere to make it non-uniform. How to make

In the chemical vapor deposition treatment (that is, thermal CVD treatment) in the temperature range of 800 to 1400 ° C. (preferably 900 to 1400 ° C., particularly 1000 to 1400 ° C.) in the method I or II, the heat treatment temperature is lower than 800 ° C. , Fusion of conductive carbon film and silicon composite, insufficient alignment (crystallization) of carbon atoms, conversely, if the temperature is higher than 1400 ° C, the structure of the silicon dioxide portion progresses and the traffic of lithium ions is hindered. Therefore, the function as a lithium ion secondary battery may be deteriorated.

On the other hand, in the disproportionation of silicon oxide in the above method I or III, if the heat treatment temperature is lower than 900 ° C., the disproportionation does not proceed at all or it is extremely long for the formation of fine cells of silicon (microcrystals of silicon). It takes time and is not efficient, and conversely, if the temperature is higher than 1400 ° C, the structure of the silicon dioxide portion progresses and the traffic of lithium ions is hindered, so that the function as a lithium ion secondary battery may deteriorate. be.

In the above method III, since the disproportionation of silicon oxide is performed at 900 to 1400 ° C., particularly 1000 to 1400 ° C. after the CVD treatment, the chemical vapor deposition (CVD) treatment temperature is lower than 800 ° C. Even in the treatment in the region, a conductive carbon film in which carbon atoms are aligned (crystallized) and a silicon composite are finally fused on the surface.

As described above, the carbon film is preferably produced by subjecting it to thermal CVD (chemical vapor deposition treatment at 800 ° C. or higher), but the time of thermal CVD is appropriately set in relation to the amount of carbon. Particles may agglomerate in this treatment, and the agglomerates are crushed with a ball mill or the like. In some cases, thermal CVD is repeated again in the same manner.

When silicon oxide represented by the general formula SiOx (0.5 ≦ x <1.6) is used as the raw material in the method (I), the disproportionation reaction is carried out at the same time as the chemical vapor deposition treatment. It is important to finely disperse silicon having a crystalline structure in silicon dioxide, in which case the treatment temperature, treatment time, type of raw material that generates organic gas, and organic matter for advancing chemical vapor deposition and disproportionation. It is necessary to select the gas concentration as appropriate. The heat treatment time ((CVD / disproportioning) time) is usually selected from the range of 0.5 to 12 hours, preferably 1 to 8 hours, particularly 2 to 6 hours, and the heat treatment time is the heat treatment temperature ((CVD / disproportioning) time). / Disproportionation) Temperature), for example, when the treatment temperature is 1000 ° C., it is preferable to carry out the treatment for at least 5 hours.

Further, in the above method II, the heat treatment time (CVD treatment time) in the case of heat treatment in an atmosphere containing organic gas and / or steam is usually in the range of 0.5 to 12 hours, particularly 1 to 6 hours. Can be done. The heat treatment time (disproportionation time) when the silicon oxide of SiOx is disproportionated in advance can be usually 0.5 to 6 hours, particularly 0.5 to 3 hours.

Further, in the above method III, the processing time (CVD processing time) when the SiOx is chemically vapor-deposited in advance can be usually 0.5 to 12 hours, particularly 1 to 6 hours, under an inert gas atmosphere. The heat treatment time (unequalization time) in the above can be usually 0.5 to 6 hours, particularly 0.5 to 3 hours.

As the organic substance used as a raw material for generating an organic substance gas, a substance capable of thermally decomposing at the above heat treatment temperature to produce carbon (graphite) is selected, particularly in a non-oxidizing atmosphere, and for example, methane, ethane, ethylene and acetylene are selected. , Propane, butane, butene, pentane, isobutane, hexane and other aliphatic or alicyclic hydrocarbons alone or in admixture, benzene, toluene, xylene, styrene, ethylbenzene, diphenylmethane, naphthalene, phenol, cresol, nitrobenzene, chlorbenzene, Examples thereof include 1- to 3-ring aromatic hydrocarbons such as inden, kumaron, pyridine, anthracene, and phenylene or a mixture thereof. Further, gas light oil, creosote oil, anthracene oil, and naphtha-decomposed tar oil obtained in the tar distillation step can also be used alone or as a mixture.

The thermal CVD (thermochemical vapor deposition treatment) and / or disproportionation treatment may be carried out by using a reaction apparatus having a heating mechanism in a non-oxidizing atmosphere, and is not particularly limited, and is a treatment by a continuous method or a batch method. Specifically, a fluidized layer reactor, a rotary reactor, a vertical mobile layer reactor, a tunnel reactor, a batch reactor, a rotary kiln, and the like can be appropriately selected according to the purpose. In this case, as the (treatment) gas, the organic gas alone or a mixed gas of the organic gas and a non-oxidizing gas such as Ar, He, H ₂ , N ₂ can be used.

In this case, a reactor in which a furnace core tube such as a rotary furnace or a rotary kiln is arranged in the horizontal direction and the furnace core tube rotates is preferable, and a chemical vapor deposition treatment is performed while rolling the silicon oxide particles. , Stable production is possible without causing agglomeration of silicon oxide particles. The rotation speed of the furnace core tube is preferably 0.5 to 30 rpm, particularly preferably 1 to 10 rpm. The reactor is not particularly limited as long as it has a furnace core tube capable of maintaining an atmosphere, a rotary groove for rotating the furnace core tube, and a heating mechanism capable of raising and holding the temperature, depending on the purpose. It is also possible to provide a raw material supply mechanism (for example, a feeder) and a product recovery mechanism (for example, a hopper), to incline the furnace core tube, or to provide a baffle plate in the furnace core tube in order to control the residence time of the raw material. The material of the core tube is not particularly limited, and ceramics such as silicon carbide, alumina, mullite, and silicon nitride, refractory metals such as molybdenum and tungsten, SUS, and quartz are appropriately selected depending on the treatment conditions and purpose. Can be used.

Further, the flow gas linear velocity u (m / sec) is set to a range in which the ratio u / u mph with the _fluidization start rate u _mph is 1.5 ≦ u / u _mph ≦ 5, so that it is more efficient. A conductive film can be formed. If the u / u _mf is smaller than 1.5, the fluidization becomes insufficient and the conductive film may vary. On the contrary, if the u / u _mf exceeds 5, secondary aggregation of particles occurs. , It may not be possible to form a uniform conductive film. Here, the fluidization start speed differs depending on the particle size, treatment temperature, treatment atmosphere, etc., and the fluidized gas (linear velocity) is gradually increased, and the powder pressure loss at that time is W (powder weight) /. It can be defined as the value of the fluidized gas linear velocity when it becomes A (fluid layer cross-sectional area). The _umf can be usually set in the range of 0.1 to 30 cm / sec, preferably about 0.5 to 10 cm / sec, and the particle size giving the _umf is generally 0.5 to 100 μm. It can be preferably 5 to 50 μm. If the particle size is smaller than 0.5 μm, secondary aggregation may occur and the surface of individual particles may not be effectively treated.

<Dope of other elements on silicon oxide particles (B)>
The silicon oxide particles (B) may be doped with an element other than silicon and oxygen. The silicon oxide particles (B) doped with elements other than silicon and oxygen are expected to improve the initial charge / discharge efficiency and cycle characteristics by stabilizing the chemical structure inside the particles. Further, since such silicon oxide particles (B) have improved lithium ion acceptability and approach the lithium ion acceptability of the composite carbon particles (A), the composite carbon particles (A) and the silicon oxide particles (B) can be used. By using the negative electrode material containing both of them, lithium ions are not extremely concentrated in the negative electrode even during rapid charging, and a battery in which metallic lithium is less likely to precipitate can be produced.

The element to be doped can usually be selected from any element as long as it is an element other than Group 18 of the periodic table, but since the silicon oxide particles (B) doped with elements other than silicon and oxygen are more stable. The elements up to the 4th cycle of the periodic table are preferable. Specifically, it can be selected from elements such as alkali metals, alkaline earth metals, Al, Ga, Ge, N, P, As, and Se up to the 4th cycle of the periodic table. In order to improve the lithium ion acceptability of the silicon oxide particles (B) doped with elements other than silicon and oxygen, the elements to be doped should be alkali metals and alkaline earth metals up to the 4th cycle of the periodic table. Is preferable, Mg, Ca, and Li are more preferable, and Li is even more preferable. These may be used alone or in combination of two or more.

The ratio of the number of atoms ( _{MD) of the doped element to the number of silicon atoms (MSi) in the silicon oxide particles (B) doped with elements other than silicon and oxygen, (MD / M Si ) is 0} . It is preferably 0.01 to 5, more preferably 0.05 to 4, and even more preferably 0.1 to 3. If M _D / M _Si is below this range, the effect of doping elements other than silicon and oxygen cannot be obtained, and if it exceeds this range, silicon and elements other than oxygen that were not consumed in the doping reaction are on the surface of the silicon oxide particles. It may remain in the silicon oxide and cause a decrease in the capacity of the silicon oxide particles.

As a method for producing silicon oxide particles (B) doped with elements other than silicon and oxygen, for example, a simple substance of the element to be doped with silicon oxide particles or a powder of a compound is mixed to create an inert gas atmosphere. Below, a method of heating at a temperature of 50 to 1200 ° C. can be mentioned. Further, for example, silicon dioxide powder and metallic silicon powder or carbon powder are mixed at a specific ratio, a simple substance of an element to be doped with the powder, or a powder of a compound is added thereto, and the mixture is filled in a reactor. After that, a method of reducing the pressure to normal pressure or a specific pressure, raising the temperature to 1000 ° C. or higher, and cooling and precipitating the gas generated by holding the pressure to obtain silicon oxide particles doped with elements other than silicon and oxygen is also mentioned. Be done.

[Negative electrode material]
<Content ratio of composite carbon particles (A) and silicon oxide particles (B)>
The negative electrode material of the present invention comprises composite carbon particles (A) and silicon oxide particles (B) having the above-mentioned physical properties suitable for the present invention [weight of composite carbon particles (A)]: [silicon oxide particles (B). Weight] = 30:70 to 99: 1, especially 40:60 to 98: 3, especially 50:50 to 95: 5, and oxidized with the composite carbon particles (A) in such a ratio. By mixing and using the silicon particles (B), the silicon oxide particles (B) having a high capacity and a small volume change due to the storage and release of Li ions are formed in the gaps formed by the composite carbon particles (A). The presence of the negative particles makes it possible to obtain a high-capacity negative electrode material having a small performance deterioration due to impaired contact with the composite carbon particles (A).

<Physical characteristics>
(Average particle size (d50))
In the negative electrode material of the present invention, the average particle size, that is, the particle size (d50) of the 50% integrated portion from the small particle side in the volume-based particle size distribution is preferably 3 μm or more and 30 μm or less. When the d50 of the negative electrode material of the present invention is 3 μm or more, it is possible to prevent an increase in irreversible capacity due to an increase in specific surface area. On the other hand, when d50 is 30 μm or less, it is possible to prevent a decrease in rapid charge / discharge property due to a decrease in the contact area between the electrolytic solution and the particles of the negative electrode material. The d50 of the negative electrode material is preferably 5 to 27 μm, more preferably 7 to 25 μm, and particularly preferably 8 to 23 μm.

(Tap density)
The tap density of the negative electrode material of the present invention is preferably 0.8 to 1.8 g / cm ³ , more preferably 0.9 to 1.7 g / cm ³ , and even more preferably 1.0 to 1.6 g · cm ³ . Is. When the tap density is within the above range, the electrolytic solution and the silicon oxide particles (B) can be present in the gaps formed by the composite carbon particles (A) when the negative electrode is used, resulting in high capacity and high rate. Characterization can be realized.
The tap density is measured by the method described in the Examples section below.

(Specific surface area)
The specific surface area of the negative electrode material of the present invention by the BET method is usually 0.5 m ² / g or more, preferably 2 m ² / g or more, more preferably 3 m ² / g or more, still more preferably 4 m ² / g or more, and particularly preferably. Is 5 m ² / g or more. Further, it is usually 30 m ² / g or less, preferably 20 m ² / g or less, more preferably 10 m ² / g or less, still more preferably 9 m ² / g or less, and particularly preferably 8 m ² / g or less. When the specific surface area is below this range, there are few parts where Li enters and exits, and the high-speed charge / discharge characteristics output characteristics and low-temperature input / output characteristics of the lithium ion secondary battery are inferior. The activity with respect to the electrolytic solution becomes excessive, and the increase in side reactions with the electrolytic solution causes a decrease in the initial charge / discharge efficiency of the battery and an increase in the amount of gas generated, and the battery capacity tends to decrease.
The specific surface area by the BET method is measured by the method described in the section of Examples described later.

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

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

As the binder resin, it is preferable to use a resin that is stable to a non-aqueous electrolytic solution and is water-insoluble. For example, rubber-like polymers such as styrene / butadiene rubber, isoprene rubber and ethylene / propylene rubber; synthetic resins such as polyethylene, polypropylene, polyethylene terephthalate, polyimide, polyacrylic acid, and aromatic polyamide; both styrene / butadiene / styrene blocks. Polymers and their hydrogenated additives, styrene / ethylene / butadiene, styrene copolymers, styrene / isoprene and styrene block copolymers and thermoplastic elastomers such as their hydrides; syndiotactic-1,2-polybutadiene, ethylene. Soft resinous polymers such as vinyl acetate copolymers and copolymers of ethylene and α-olefins having 3 to 12 carbon atoms; polytetrafluoroethylene / ethylene copolymers, polyvinylidene fluorides, polypentafluoro A fluorinated polymer such as propylene and polyhexafluoropropylene can be used. As the organic medium, for example, N-methylpyrrolidone and dimethylformamide can be used.

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

The amount of the binder resin used is preferably 10 parts by weight or less, more preferably 7 parts by weight or less, based on 100 parts by weight of the negative electrode material. By reducing the amount of the binder resin to 10 parts by weight or less with respect to 100 parts by weight of the negative electrode material, it is possible to prevent a decrease in the capacity of the negative electrode and prevent alkaline ions such as lithium ions from entering and exiting the negative electrode material. You can prevent problems.

Examples of the thickener to be added to the slurry include water-soluble celluloses such as carboxymethyl cellulose, methyl cellulose, hydroxyethyl cellulose and hydroxypropyl cellulose, polyvinyl alcohol, polyethylene glycol and the like. Of these, carboxymethyl cellulose is preferable. The thickener is preferably used so as to be usually 0.1 to 10 parts by weight, particularly 0.2 to 7 parts by weight, based on 100 parts by weight of the negative electrode material.

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

After applying and drying the slurry of the negative electrode material and the binder resin to the current collector, pressurize it to increase the density of the active material layer formed on the current collector, and increase the density of the battery per unit volume of the negative electrode active material layer. It is preferable to increase the capacity. The density of the active material layer is preferably in the range of 1.2 to 1.8 g / cm ³ , and more preferably 1.3 to 1.6 g / cm ³ .

By setting the density of the active material layer to 1.2 g / cm ³ or more, it is possible to prevent a decrease in battery capacity due to an increase in the thickness of the electrodes. Further, by setting the density of the active material layer to 1.8 g / cm ³ or less, the amount of the electrolytic solution held in the voids decreases as the interparticle voids in the electrode decrease, and the mobility of alkaline ions such as lithium ions decreases. It is possible to prevent the rapid charge / discharge property from becoming small.

The negative electrode active material layer is preferably composed of silicon oxide particles (B) present in the gaps formed by the composite carbon particles (A). The presence of the silicon oxide particles (B) in the gaps formed by the composite carbon particles (A) can increase the capacity and improve the rate characteristics.

The pore capacity in the range of 10 nm to 100,000 nm by the mercury intrusion method of the negative electrode active material layer formed by using the negative electrode material of the present invention is preferably 0.05 ml / g, preferably 0.1 ml / g or more. Is more preferable. By setting the pore capacity to 0.05 ml / g or more, the area of entry and exit of alkaline ions such as lithium ions becomes large.

[Non-water-based secondary battery]
The non-aqueous secondary battery of the present invention is a non-aqueous secondary battery including a positive electrode, a negative electrode, and an electrolyte, and uses the negative electrode of the present invention as the negative electrode.

The non-aqueous secondary battery of the present invention can be produced according to a conventional method except that the above-mentioned negative electrode of the present invention is used.

[Positive electrode]
Examples of the positive electrode material used as the active material for the positive electrode of the non-aqueous secondary battery of the present invention include a lithium cobalt composite oxide having a basic composition represented by LiCoO ₂ , a lithium nickel composite oxide represented by LiNiO ₂ , and LiMnO. A lithium transition metal composite oxide such as the lithium manganese composite oxide represented by ₂ and LiMn _{2 O4} , a transition metal oxide such as manganese dioxide, and a mixture of these composite oxides may be used. Furthermore, TiS ₂ , FeS ₂ , Nb ₃ S ₄ , Mo ₃ S ₄ , CoS ₂ , V ₂ O ₅ , CrO ₃ , V ₃ O ₃ , FeO ₂ , GeO ₂ and LiNi _0.33 Mn _0.33 Co ₀ . _.33 O ₂ , LiFePO ₄ , etc. may be used.

A positive electrode can be produced by slurrying the positive electrode material with a binder resin with an appropriate solvent, applying it to a current collector, and drying it. It is preferable that the slurry contains a conductive material such as acetylene black and ketjen black. Further, a thickener may be contained if desired.

As the thickener and the binder resin, those known for this application, for example, those exemplified as those used for producing a negative electrode may be used. The blending ratio with respect to 100 parts by weight of the positive electrode material is preferably 0.5 to 20 parts by weight, and particularly preferably 1 to 15 parts by weight. The thickener is preferably 0.2 to 10 parts by weight, and particularly preferably 0.5 to 7 parts by weight.

The blending ratio of the binder resin to 100 parts by weight of the positive electrode material is preferably 0.2 to 10 parts by weight, particularly preferably 0.5 to 7 parts by weight when the binder resin is slurryed with water. When the binder resin is slurryed with an organic solvent that dissolves the binder resin such as N-methylpyrrolidone, 0.5 to 20 parts by weight, particularly 1 to 15 parts by weight is preferable.

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

[Electrolytes]
The electrolyte used in the non-aqueous secondary battery of the present invention may be an all-solid electrolyte or an electrolytic solution in which the electrolyte is contained in a non-aqueous solvent, but the electrolyte is preferably contained in the non-aqueous solvent. It is an electrolyte.

As the electrolytic solution, a solution obtained by dissolving various lithium salts in a conventionally known non-aqueous solvent can be used. Examples of the non-aqueous solvent include cyclic carbonates such as ethylene carbonate, fluoroethylene carbonate, propylene carbonate, butylene carbonate and vinylene carbonate, chain carbonates such as dimethyl carbonate, ethylmethyl carbonate and diethyl carbonate, and cyclic esters such as γ-butyrolactone. , Crown ether, 2-methyltetrahydrofuran, tetrahydrofuran, 1,2-dimethyltetrahydrofuran, cyclic ether such as 1,3-dioxolane, chain ether such as 1,2-dimethoxyethane and the like may be used. Usually, two or more of these are mixed and used. Of these, it is preferable to use cyclic carbonate and chain carbonate, or a mixture thereof with another solvent.

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

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

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

[Negative electrode / Positive electrode capacity ratio]
The non-aqueous secondary battery of the present invention is preferably designed with a negative electrode / positive electrode capacity ratio of 1.01 to 1.5, and more preferably 1.2 to 1.4.
The non-aqueous secondary battery of the present invention is preferably a lithium ion secondary battery including a positive electrode and a negative electrode capable of storing and releasing Li ions, and an electrolyte.

Hereinafter, the content of the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples as long as the gist of the present invention is not exceeded. The values of various production conditions and evaluation results in the following examples have meanings as preferable values of the upper limit or the lower limit in the embodiment of the present invention, and the preferable ranges are the above-mentioned upper limit or lower limit values and the following. It may be in the range specified by the value of Examples or the combination with the values of Examples.

[Measurement / evaluation method of physical properties or characteristics]
[Measurement of physical properties of composite carbon particles (A), silicon oxide particles (B), and negative electrode material]
<Particle size distribution>
For the volume-based particle size distribution, the sample is dispersed in a 0.2 wt% aqueous solution (about 10 mL) of polyoxyethylene (20) sorbitan monolaurate, which is a surfactant, and a laser diffraction / scattering particle size distribution meter LA- It was measured using 700 (manufactured by HORIBA, Ltd.).

<Tap density>
The measurement was performed using a powder density measuring instrument Tap Denser KYT-3000 (manufactured by Seishin Corporation). After dropping the sample into a 20 cc tap cell and filling the cell fully, tapping with a stroke length of 10 mm was performed 1000 times, and the density at that time was taken as the tap density.

<Specific surface area (BET method)>
The measurement was performed using Tristar II 3000 manufactured by Micromeritics. After drying under reduced pressure at 150 ° C. for 1 hour, the measurement was carried out by the BET multipoint method (5 points in the range of relative pressure of 0.05 to 0.30) by adsorption of nitrogen gas.

<Circularity>
Using a flow-type particle image analyzer (FPIA-2000 manufactured by Toa Medical Electronics Co., Ltd.), the particle size distribution based on the equivalent circle diameter was measured and the average circularity was calculated. Ion-exchanged water was used as the dispersion medium, and polyoxyethylene (20) monolaurate was used as the surfactant. The equivalent circle diameter is the diameter of a circle (equivalent circle) having the same projected area as the captured particle image, and the circularity is the peripheral length of the captured particle projected image with the peripheral length of the equivalent circle as the molecule. This is the ratio used as the denominator. The circularity of the measured particles having an equivalent diameter in the range of 10 to 40 μm was averaged and used as the circularity.

<Raman R value>
The Raman spectrum was measured with a Raman spectroscope. Specifically, the particles to be measured are naturally dropped into the measurement cell to fill the sample, and while irradiating the measurement cell with argon ion laser light, the measurement cell is rotated in a plane perpendicular to the laser light. Measurements were made.
Wavelength of argon ion laser light: 514.5 nm
Laser power on sample: 25 mW
Resolution: 4 cm ^-1
Measurement range: 1100 cm ^-1 to 1730 cm ^-1
Peak intensity measurement, peak half width measurement: background processing, smoothing processing (convolution 5 points by simple average)

In the Raman spectrum obtained by this measurement, the intensity ratio _R (R =) when the intensity _IA of the peak PA near 1580 cm ^-1 and the intensity IB of the peak P _B near 1360 cm ^-1 were measured. It was defined as _{IB / I A )} . The term "near 1580 cm ^-1 " refers to the range of 1580 to 1620 cm ^-1 , and the term "near 1360 cm ^-1 " refers to the range of 1350 to 1370 cm ^-1 .

[Battery evaluation]
<Manufacturing of negative electrode for performance evaluation>
97.5% by weight of a mixture of composite carbon particles (A) and silicon oxide particles (B) described later, 1% by weight of carboxymethyl cellulose (CMC) as a binder, and 48% by weight of styrene-butadiene rubber (SBR) aqueous dispersion 3 .1% by weight (SBR: 1.5% by weight) was kneaded with a hybridizing mixer to obtain a slurry. This slurry was applied onto a copper foil having a thickness of 20 μm by a blade method so as to have a basis weight of 4 to 5 mg / cm ² , and dried.

Then, the negative electrode active material layer is roll-pressed to a density of 1.2 to 1.4 g / cm ³ to obtain a negative electrode sheet, and the negative electrode sheet is punched into a circular shape having a diameter of 12.5 mm, and the temperature is 90 ° C. for 8 hours. It was vacuum dried and used as a negative electrode for evaluation.

<Manufacturing of non-water-based secondary batteries (coin-type batteries)>
An evaluation negative electrode produced by the above method and a lithium metal foil punched into a disk shape having a diameter of 15 mm were used as counter electrodes. A separator (porous polyethylene film) impregnated between the two electrodes with an electrolytic solution in which LiPF ₆ is dissolved in a mixed solvent of ethylene carbonate and ethylmethyl carbonate (volume ratio = 3: 7) so as to be 1 mol / L. A coin-shaped battery for performance evaluation was manufactured.

<Charge capacity, discharge capacity, efficiency, coin cycle maintenance rate>
Using the non-aqueous secondary battery (coin-type battery) produced by the above method, the charge capacity (mAh / g) and the discharge capacity (mAh / g) at the time of charging and discharging the battery were measured by the following measurement methods.
Charge to 5 mV with respect to the lithium counter electrode at a current density of 0.05 C, further charge until the current density reaches 0.005 C at a constant voltage of 5 mV, dope lithium into the negative electrode, and then a current density of 0.1 C. The current was discharged to 1.5 V with respect to the lithium counter electrode.
The charge capacity and discharge capacity were calculated as follows. The weight of the negative electrode active material is obtained by subtracting the weight of the copper foil punched to the same area as the negative electrode from the weight of the negative electrode and multiplying by the coefficient obtained from the composition ratio of the negative electrode active material and the binder. The charge capacity and the discharge capacity per weight were obtained by dividing the charge capacity and the discharge capacity of the eyes.
The charge capacity (mAh / g) at this time was defined as the 1st charge capacity (mAh / g) of the negative electrode material, and the discharge capacity (mAh / g) was defined as the 1st discharge capacity (mAh / g).
Further, the discharge capacity (mAh / g) of the first cycle obtained here was divided by the charge capacity (mAh / g), and the value multiplied by 100 was taken as the 1st efficiency (%).
The above operation was carried out for 10 cycles, the discharge capacity of the 10th cycle was divided by the discharge capacity of the 1st cycle, and the value multiplied by 100 was taken as the coin cycle maintenance rate.

[Composite carbon particles (A)]
<Composite carbon particles (A1)>
Fragment-like natural graphite having a d50 of 100 μm was spheroidized by mechanical action for 5 minutes at a rotor peripheral speed of 85 m / sec using a hybridization system NHS-1 manufactured by Nara Machinery Co., Ltd. This sample was treated by classification to obtain spherical graphite particles with a d50 of 7.5 μm. Carbon black having a primary particle diameter of 24 nm, a BET specific surface area (SA) of 115 m ² / g, and a DBP oil absorption of 110 mL / 100 g was added to the obtained spherical graphite particles in an amount of 2.0% by weight based on the graphite particles. It was added, mixed and stirred. The mixed powder is mixed with petroleum-based heavy oil obtained during thermal decomposition of naphtha as a carbonaceous precursor, heat-treated at 1300 ° C in an inert gas, and then the calcined product is crushed and classified to make graphite. Composite carbon particles (A1) in which carbon black fine particles and amorphous carbon were impregnated on the surface of the quality particles were obtained.

From the firing yield, in the obtained composite carbon particles (A1), the weight ratio of the spherical graphite particles to the amorphous carbon (sphericized graphite particles: amorphous carbon) is 1: 0.015. confirmed. The physical properties of the composite carbon particles (A1) were measured by the above-mentioned measuring method. The results are shown in Table 1.

<Composite carbon particles (a1)>
Composite carbon particles (a1) were produced in the same manner as the composite carbon particles (A1) except that carbon black was not added. From the calcined yield, in the obtained composite carbon particles (a1), the mass ratio of the spherical graphitic particles to the amorphous carbon (spherical graphitic particles: amorphous carbon) is 1: 0.015. It was confirmed that. The physical characteristics of the composite carbon particles (a1) were measured. The results are shown in Table 1.

[Silicon oxide particles (B)]
<Silicon oxide particles (B1)>
Commercially available silicon oxide particles (SiOx, x = 1) (manufactured by Osaka Titanium Technologies Co., Ltd.) were used as silicon oxide particles (B1). The silicon oxide particles (B1) had a d50 of 5.6 μm and a BET method specific surface area of 3.5 m ² / g. From the X-ray diffraction pattern of the silicon oxide particles (B1), the diffraction line attributed to Si (111) near 2θ = 28.4 ° could not be confirmed, and the silicon oxide particles (B1) had a zero valence. It was confirmed that it did not contain silicon atoms as microcrystals.

<Silicon oxide particles (B2)>
The silicon oxide particles (B1) were heat-treated at 1000 ° C. for 6 hours in an inert atmosphere to obtain silicon oxide particles (B2). The silicon oxide particles (B2) had a d50 of 5.4 μm and a BET method specific surface area of 2.1 m ² / g. From the X-ray diffraction pattern of the silicon oxide particles (B2), it is possible to confirm the diffraction line attributed to Si (111) near 2θ = 28.4 °, and the silicon oxide particles (B2) have a zero value. It was confirmed that the silicon atom of was contained as a microcrystal. The particle size of the silicon crystal determined by the Scheller's formula based on the spread of the diffraction lines was 3.2 nm.

Table 2 summarizes the physical characteristics of the silicon oxide particles (B1) and (B2).

[Example 1]
10 parts by weight of silicon oxide particles (B1) was dry-mixed with 90 parts by weight of the composite carbon particles (A1) to prepare a mixture. Each evaluation was performed by the above-mentioned measurement method.

[Example 2]
10 parts by weight of silicon oxide particles (B2) was dry-mixed with 90 parts by weight of the composite carbon particles (A1) to prepare a mixture. Evaluation was performed in the same manner as in Example 1.

[Comparative Example 1]
10 parts by weight of silicon oxide particles (B1) was dry-mixed with 90 parts by weight of the composite carbon particles (a1) to prepare a mixture. Evaluation was performed in the same manner as in Example 1.

Table 4 summarizes the physical characteristics of the mixtures obtained in Examples 1 and 2 and Comparative Example 1.
In addition, Table 4 summarizes the evaluation results of the batteries produced by using the negative electrode material composed of the mixtures obtained in Examples 1 and 2 and Comparative Example 1.
From Table 4, it can be seen that the non-aqueous secondary battery using the negative electrode material of the present invention has a high capacity and is excellent in initial efficiency and cycle characteristics.

Claims (14)

It contains composite carbon particles (A) and silicon oxide particles (B) (excluding composite particles containing at least silicon oxide particles and graphite particles), and the composite carbon particles (A) are at least graphite particles and carbon. A carbon material for the negative electrode of a non-aqueous secondary battery containing pledges and carbonaceous particles.
Uniform and continuous fine flow paths are formed on the surface of the composite carbon particles (A).
The content ratio of the composite carbon particles (A) and the silicon oxide particles (B) [weight of the composite carbon particles (A)]: [weight of the silicon oxide particles (B)] is 30:70 to 99: 1. Negative electrode material for non-aqueous secondary batteries. The negative electrode material for a non-aqueous secondary battery according to claim 1, wherein the composite carbon particles (A) contain spherical graphite. The negative electrode material for a non-aqueous secondary battery according to claim 1 or 2, wherein the composite carbon particles (A) contain spherical graphite of scaly natural graphite. The negative electrode material for a non-aqueous secondary battery according to any one of claims 1 to 3, wherein the composite carbon particles (A) have a circularity of 0.88 or more. The negative electrode material for a non-aqueous secondary battery according to any one of claims 1 to 4, wherein the average particle diameter (d50) of the silicon oxide particles (B) is 0.3 μm or more and 15 μm or less. The non-aqueous secondary battery according to any one of claims 1 to 5, wherein the particle diameter (d10) of the 10% integrating portion from the small particle side of the silicon oxide particles (B) is 0.001 μm or more and 6 μm or less. Negative electrode material. Any of claims 1 to 6, wherein the ratio ( _MO / M _Si ) of the number of _oxygen atoms (MO) to the number of silicon atoms (M _Si ) in the silicon oxide particles (B) is 0.5 to 1.6. The negative electrode material for a non-aqueous secondary battery according to item 1. The carbon material for a negative electrode of a non-aqueous secondary battery according to any one of claims 1 to 7, wherein the silicon oxide particles (B) contain zero-valent silicon atoms. The negative electrode material for a non-aqueous secondary battery according to any one of claims 1 to 8, which contains microcrystals of silicon in the silicon oxide particles (B). Any of claims 1 to 9, wherein the silicon oxide particles (B) are composite silicon oxide particles having silicon oxide particles as nuclei and a carbon layer made of amorphous carbon on at least a part of the surface thereof. The carbon material for the negative electrode of the non-aqueous secondary battery according to Item 1. The carbon material for a negative electrode of a non-aqueous secondary battery according to any one of claims 1 to 9, wherein the silicon oxide particles (B) are silicon oxide particles doped with elements other than silicon and oxygen. The negative electrode for a non-aqueous secondary battery including a current collector and an active material layer formed on the current collector, wherein the active material layer is the non-one according to any one of claims 1 to 11. A negative electrode for a non-aqueous secondary battery, which contains a negative electrode material for an aqueous secondary battery. A non-aqueous secondary battery comprising a positive electrode, a negative electrode, and an electrolyte, wherein the negative electrode is the negative electrode for the non-aqueous secondary battery according to claim 12. At least graphite particles, carbonaceous substances, and carbonaceous particles are composited to form uniform and continuous fine flow paths on the surface to produce composite carbon particles (A), and the composite carbon particles (A) and silicon oxide particles are produced. Production of negative electrode material for non-aqueous secondary batteries in which the content ratio with (B) [weight of composite carbon particles (A)]: [weight of silicon oxide particles (B)] is mixed at 30:70 to 99: 1. Method.