JP6977504B2 - Negative electrode material for non-aqueous secondary batteries, negative electrode for non-aqueous secondary batteries and non-aqueous secondary batteries - Google Patents

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 comprising a positive electrode and a negative electrode capable of occluding and releasing lithium ions and a non-aqueous electrolyte solution in which a lithium salt such _{as LiPF 6} or LiBF _{4 is dissolved has been developed and put into practical use.}

Various negative electrode materials have been proposed for this non-aqueous lithium secondary battery, but at present, a negative electrode material using a carbon material is widely used. On the other hand, in order to dramatically improve the performance from the viewpoint of increasing the capacity, development other than carbon materials is being promoted, and one of the typical ones is silicon and silicon oxide (SiOx) which is amorphous. ..

As a negative electrode active material for a lithium ion secondary battery, silicon and amorphous silicon oxide (amorphous silicon oxide) have an advantage in that they have a large capacity, but they deteriorate significantly when repeatedly charged and discharged, that is, they have a large capacity. In the current situation, the cycle characteristics are inferior, and the initial efficiency is particularly low, so that it has not been put into practical use except for some parts. As a solution to such a problem, Patent Documents 1 and 2 use a silicon-based compound having a domain structure in which silicon microcrystals are dispersed in a silicon-based compound (particularly silicon oxide) as a negative electrode material. It has been disclosed.

Japanese Unexamined Patent Publication No. 2004-047404 Japanese Unexamined Patent Publication No. 2004-323284

In Patent Documents 1 and 2, a silicon-based compound having a domain structure in which microcrystals of silicon are dispersed in a silicon-based compound (particularly a silicon oxide) is converted into silicon and amorphous silicon oxide (amorphous silicon oxide). On the other hand, although it is described that the cycle characteristics and initial efficiency when repeatedly charged and discharged are excellent, and that a carbon material is used in combination as a conductive material as a negative electrode material, it has been described by the present inventors. In the negative electrode materials of Patent Documents 1 and 2, the problem that the balance between the discharge capacity and the initial efficiency is insufficient has been found.
That is, an object of the present invention is to provide a negative electrode material for a non-aqueous secondary battery having a high capacity and excellent initial efficiency, and a negative electrode for a non-aqueous secondary battery and a non-aqueous secondary battery using the negative electrode material. be.

As a result of diligent studies by the present inventors to solve the above problems, the above problems are solved by using a specific composite carbon particle in combination with silicon oxide particles having a specific domain structure due to a disproportionation reaction. I found that it could be done.
That is, the gist of the present invention is as follows.

[1] The silicon oxide particles (A) and the composite carbon particles (B) are contained, the silicon oxide particles (A) contain zero-valent silicon atoms, and the composite carbon particles (B) are spherical graphite particles. A carbon material for a negative electrode of a non-aqueous secondary battery having a carbon layer on at least a part of the surface of the particle and having a circularity of 0.89 or more obtained by flow-type particle image analysis.

[2] The negative electrode material for a non-aqueous secondary battery according to [1], which contains silicon microcrystals in the silicon oxide particles (A).

[3] is the ratio _(M O _/ M _Si) of 0.5 to 1.6 silicon oxide particles (A) in the number of silicon atoms _{(M Si)} to the number of oxygen atoms _{(M O),} [1] or [ 2] The negative electrode material for a non-aqueous secondary battery.

[4] The negative electrode for a non-aqueous secondary battery according to any one of [1] to [3], wherein the composite carbonaceous particles (B) contain graphite obtained by spheroidizing natural graphite in the form of scales, scales, or lumps. Material.

[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 (A) is 0.01 μm or more and 20 μm or less.

[6] The non-aqueous system 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 (A) is 0.001 μm or more and 6 μm or less. Negative electrode material for secondary batteries.

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

[8] 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 [7]. A negative electrode for a non-aqueous secondary battery, which comprises the above-described negative electrode material for a non-aqueous secondary battery.

[9] 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 [8].

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

Hereinafter, the present invention will be described in detail, but the present invention is not limited to the following description, and can be arbitrarily modified and 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.

[Carbon material for negative electrode of non-aqueous secondary battery]
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 silicon oxide particles (A) (hereinafter, “silicon oxide particles of the present invention (hereinafter,”). The silicon oxide particles (A) include composite carbon particles (B) (hereinafter, may be referred to as “composite carbon particles (B)” of the present invention). It contains a zero-valent silicon atom, and the composite carbon particles (B) have a carbon layer on at least a part of the surface of the spherical graphite particles, and the circularity obtained from the flow-type particle image analysis (described later). The average circularity of the composite carbon particles (B) measured by the method) is 0.89 or more.

[mechanism]
<Working mechanism based on silicon oxide particles (A)>
The negative electrode material of the present invention contains silicon oxide particles (A) having a high capacity and a small volume change due to occlusion / release of Li ions, so that the contact with the composite carbon particles (B) is impaired and the performance is deteriorated. It is possible to obtain a small, high-capacity negative electrode material.
In particular, by silicon atoms in the silicon oxide particles (A) of the present invention _{(M Si)} to the number of oxygen atoms ratio _{(M O) (M O /} M Si) is 0.5 to 1.6, high At the same time as the capacity, the amount of volume change due to occlusion / release of Li ions becomes close to the amount of volume change of carbonaceous particles, and it is possible to reduce the deterioration of performance due to impaired contact with carbonaceous particles. ..
Further, since the silicon oxide particles (A) contain zero-valent silicon atoms, the range of potential for storing and releasing Li ions becomes close to that of the composite carbon particles (B), and the volume changes due to the storage and release of Li ions. Is generated at the same time as the composite carbon particles (B), so that the relative positional relationship between the composite carbon particles (B) and the silicon oxide particles (A) is maintained, and the contact with the composite carbon particles (B) is impaired. It is possible to reduce the decrease.

<Working mechanism based on composite carbon particles (B)>
The composite carbon particles (B) of the present invention have excellent low-temperature input / output characteristics because they have a carbon layer on the surface that facilitates the insertion and desorption of Li ions. Further, since the particles have a carbon layer, the particles are hard and difficult to be deformed during electrode rolling, and the circularity of the particles is high, so that the silicon oxide particles (A) are present in the gaps between the composite carbon particles (B) and are electrolyzed in the electrode. It is considered that the flow path for the liquid to move is secured, the diffusion path of Li ions is improved, and the input / output characteristics, charge / discharge rate characteristics, electrolysis resistance performance, and cycle characteristics at low temperature are improved.

<Working mechanism by blending silicon oxide particles (A) and composite carbon particles (B)>
When the negative electrode material of the present invention is used as a negative electrode, the composite carbon particles (B) formed by the composite carbon particles (B) having a carbon layer in the negative electrode, which are hard to be deformed because the particles are hard, and have high circularity of the particles are formed. By allowing the silicon oxide particles (A) to exist in the gaps between the particles having a large volume, it is possible to absorb the volume change of the silicon oxide particles (A) during charging and discharging in the gaps formed by the composite carbon particles (B). Therefore, the conductive path breakage is suppressed. As a result, it is considered that an excessive current can be suppressed from flowing only to a specific portion of the silicon oxide particles (A) and the composite carbon particles (B) in the electrode, and a high capacity and excellent initial efficiency can be obtained. ..

[Silicon oxide particles (A)]
<Structure>
The silicon oxide particles (A) of the present invention contain zero-valent silicon atoms. Further, it is preferable that the silicon oxide particles (A) contain microcrystals of silicon.

The ratio of the number of silicon atoms in the silicon oxide particles (A) of the present invention _{(M Si)} to the number of oxygen atoms _{(M O) (M O /} M Si) is preferably 0.5 to 1.6, also , 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 (B) 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 (A) are filled in the gaps formed by the composite carbon particles (B) while ensuring contact points with the composite carbon particles (B), whereby alkaline ions such as Li ions are occluded by charging and discharging. -The volume change of the silicon oxide particles (A) due to the discharge 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 (A).

Silicon oxide particles (A) containing zero-valent silicon atoms are ^{usually centered around -110 ppm present in silicon oxide in solid-state 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 particularly preferable that there is a broad peak (P2) centered at −70 ppm and 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 (A) 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 (A) containing zero-valent silicon atoms generate hydrogen when an alkali hydroxide is allowed to act on the particles (A). The amount of zero-valent silicon atoms in the silicon oxide particles (A) 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 (A) 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 (A) 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>
(Average particle size (d50))
The average particle size (particle size of the 50% integrated portion from the small particle side in the volume particle size distribution) (d50) of the silicon oxide particles (A) of the present invention is preferably 0.1 μm or more and 20 μm or less. If the d50 of the silicon oxide particles (A) is in the above range, the silicon oxide particles (A) are present in the gaps formed by the composite carbon particles (B) 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 (A) due to the occlusion / 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 (A) is more preferably 0.5 to 15 μm, still more preferably 1 to 10 μm, and particularly preferably 1.5 to 8 μm.

In the volume particle size distribution of the silicon oxide particles (A) of the present invention, the particle size (d10) of the 10% integrating 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 (A) is in the above range and appropriate fine particles are present, the silicon oxide particles (A) existing in the gaps between the composite carbon particles (B) 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 (A) is more preferably 0.01 to 4 μm, still more preferably 0.1 to 3 μm.

In the volume particle size distribution of the silicon oxide particles (A) of the present invention, the particle size (d90) of the 90% integrating portion from the small particle side is preferably 1 μm or more and 40 μm or less. When d90 is in the above range, the silicon oxide particles (A) are likely to exist in the gaps between the composite carbon particles (B), a good conductive path can be obtained, and the cycle characteristics are good. The d90 of the silicon oxide particles (A) is more preferably 1.5 to 30 μm, still more preferably 2 to 20 μm, and particularly preferably 3 to 10 μm.

<Average particle size ratio>
The average particle size of the silicon oxide particles (A) of the present invention (the particle size of the 50% integrated portion from the small particle side in the volume particle size distribution) d50 and the average particle size of the composite carbon particles (B) of the present invention (in the volume size size distribution). Ratio with d50 (particle size of 50% integration part from the small particle side) (R = [average particle size of silicon oxide particles (A) (d50)] / [average particle size of composite carbonaceous particles (B) (d50)) ]) Is preferably 0.001 or more and 10 or less.
When the average particle size ratio R is 0.001 or more, an increase in the specific surface area can be suppressed and the irreversible capacity can be reduced. (A) can be present, and the volume change of the silicon oxide particles (A) 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 (B). Therefore, it is possible to suppress the conductive path breakage due to the volume change of the silicon oxide particles (A), and as a result, the cycle characteristics are improved. The average particle size ratio R is more preferably 0.01 to 3, more preferably 0.1 to 1, particularly preferably 0.15 to 0.8, and most preferably 0.2 to 0.2. It is 0.6.

The silicon oxide particles (A) d50, d10, d90 of the present invention, the composite carbon particles (B) of the present invention described later d50, d90, d10, and the negative electrode material d50 of the present invention described later will be described later. It is a value measured based on a volume-based particle size distribution by the method described in the section of the above-mentioned Examples.

(Specific surface area)
The specific surface area of the silicon oxide particles (A) of the present invention according to the BET method ^{is preferably 80 m 2} / g or less, and ^{more 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 (A) by the BET method is within the above range, the efficiency of input / output of alkaline ions such as lithium ions can be maintained satisfactorily, and the silicon oxide particles (A) have a suitable size. , Can be present in the gap formed by the composite carbon particles (B), and a conductive path with the composite carbon particles (B) can be secured. Further, since the silicon oxide particles (A) 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 (A)>
The silicon oxide particles are usually _{obtained by thermally reducing SiO 2 using silicon dioxide (SiO 2} ) as a raw material and using metallic silicon (Si) and / or carbon, and the value of x of SiOx is 0 <x <. It is a general term for particles composed of silicon oxide represented by 2 (however, as described later, it is also possible to dope other elements other than silicon and carbon, and in this case, the composition formula is different from SiOx. However, such a thing is also included in the silicon oxide particles (A) 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.

The silicon oxide particles (A) of the present invention contain zero-valent silicon atoms as described above, and such silicon oxide particles (A) are, for example, silicon oxide particles produced as follows (A). It can be produced by subjecting A1) or silicon oxide particles (A2) to a disproportionation treatment described later.

The silicon oxide particles to be subjected to the disproportionation treatment when producing the silicon oxide particles (A) used in the present invention have the silicon oxide particles as nuclei and have a carbon layer made of amorphous carbon on at least a part of the surface thereof. It may be a composite type silicon oxide particles. As the silicon oxide particles, one selected from the group consisting of silicon oxide particles (A1) having no carbon layer made of amorphous carbon and composite silicon oxide particles (A2) may be used alone. Two or more kinds may be used together. 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 (A1)>
The method for producing the silicon oxide particles (A1) is not limited, and for example, silicon oxide particles produced by the method described in Japanese Patent No. 3952118 can be used. 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 then 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, the silicon oxide particles (A) satisfying the above physical characteristics can be formed by a method of giving a motion in which these are combined.

<Manufacturing method of composite silicon oxide particles (A2)>
The method for producing composite silicon oxide particles (A2) 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 (A1) 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 (A2) 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 (A) of the present invention are produced by further heat-treating the silicon oxide particles (A1) and the composite type silicon oxide particles (A2) produced as described above to disqualify them. By applying the disproportioning treatment, a structure in which zero-valent silicon atoms are unevenly distributed as Si fine crystals in the amorphous SiOx is formed, and the Si fine crystals in the amorphous SiOx form the negative electrode of the present invention. As described in the section of material mechanism, the range of potential for storing and releasing Li ions is close to that of the composite carbon particles (B), and the volume change due to the storage and release of Li ions is simultaneously with the composite carbon particles (B). Therefore, the relative positional relationship between the composite carbon particles (B) and the silicon oxide particles (A) is maintained, and it is possible to reduce the performance deterioration due to the impaired contact with the composite carbon particles (B). ..

This disproportionation treatment can be performed by heating the above-mentioned silicon oxide particles (A1) or composite silicon oxide particles (A2) 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, it is possible to use (process) as the gas, Ar, the He, inert gas alone or a mixed gas thereof at H _2, N _2, etc. of the processing temperature.

<Carbon coating / Manufacture of silicon microcrystal dispersed silicon oxide particles>
As described below, the silicon oxide particles (A) of the present invention are composite silicon oxide particles in which the surface of silicon oxide particles containing fine crystals of silicon is coated with carbon, and carbon coating and disproportionation treatment are simultaneously performed. Can also be manufactured.

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 more preferably 105 to 1300 ° C., further 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 with, composite that silicon fine particles are coated with silicon dioxide by the solgel method, silicon fine powder is solidified via fuming silica, fine powder silica such as precipitated silica and water. A composite obtained by sintering the dried product, or pulverized 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 is chemically vapor-deposited by heat-treating the material heated in 1 in a temperature range of 800 to 1400 ° C., preferably 900 to 1300 ° C., more preferably 1000 to 1200 ° C. in an atmosphere containing at least an organic gas and / or steam. 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 aggregate in this treatment, and the aggregates 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 a raw material in the method I above, a disproportionation reaction is carried out at the same time as the chemical vapor deposition treatment. It is important to finely disperse silicon having a crystal 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 method III above, 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 (non-uniformization 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 indene, 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 furnace core tube is also 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.

Also, the fluidizing gas linear velocity u (m / sec), by a range of the ratio u _{/ u mf} the fluidization velocity _{u mf} is _{1.5 ≦ u / u mf ≦ 5} , more efficiently A conductive film can be formed. If u / u _mph is smaller than 1.5, fluidization may be insufficient and the conductive film may vary. On the contrary, if u / u _mph 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 speed) 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 (fluidized bed cross-sectional area). _{Incidentally, u mf} is usually 0.1 to 30 cm / sec, preferably be in a range of about 0.5 to 10 cm / sec, typically 0.5~100μm as particle size to give this _{u mf} It can be preferably 5 to 50 μm. If the particle size is smaller than 0.5 μm, secondary agglutination may occur and the surface of individual particles may not be effectively treated.

<Dope of other elements on silicon oxide particles (A)>
The silicon oxide particles (A) may be doped with an element other than silicon and oxygen. The silicon oxide particles (A) 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 (A) have improved lithium ion acceptability and approach the lithium ion acceptability of the composite carbon particles (B), the composite carbon particles (B) and the silicon oxide particles (A) 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 (A) doped with elements other than silicon and oxygen are more stable. Elements up to the 4th period 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 (A) 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.

Silicon, the ratio of oxygen than the elements doped silicon oxide particles (A) in the number of silicon atoms _{(M Si)} atoms doped element to _{(M D),} as the _{(M D / M Si),} 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 (A) doped with an element 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. is 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.

[Composite carbon particles (B)]
<Structure>
The composite carbon particles (B) of the present invention are composite carbonaceous particles having a carbon layer on at least a part of the surface of the spheroidized graphite particles. Here, "having a carbon layer on at least a part of the surface" means that the carbon layer not only covers a part or the whole of the surface of the graphite particles in a layered manner, but also the carbon layer adheres to a part or the whole of the surface.・ Includes the form of graphite. The carbon layer may be provided so as to cover the entire surface, or may be partially coated or adhered / adhered, but preferably covers the entire surface. Such composite carbon particles (B) include, for example, composite graphite having a carbon layer made of amorphous carbon on at least a part of the surface of the spheroidized graphite particles (also referred to as “amorphous carbon-coated graphite”). ), And composite graphite (also referred to as “graphite-coated graphite”) having a carbon layer made of graphite on at least a part of the surface of the spheroidized graphite particles can be used. The composite carbon particles (B) of the present invention may be used alone or in combination of two or more. In order to confirm that the carbon layer is provided on at least a part of the surface of the graphite particles, it can be confirmed by, for example, a TEM photograph.

As the spheroidized graphite particles having a carbon layer, for example, scaly, lumpy or plate-shaped naturally occurring graphite, petroleum coke, coal pitch coke, coal needle coke, mesophase pitch and the like are heated to 2500 ° C. or higher. By applying mechanical energy treatment to the artificial graphite produced in the above process, graphite particles formed in the form of particles can be used. In the negative electrode material for a non-aqueous secondary battery, the carbon layer of the composite carbon particles (B) may be a graphitic material and / or amorphous carbon, and is preferably amorphous carbon.

The coverage of the carbon layer of the composite carbon particles (B) of the present invention is the amount of the carbon layer existing on the surface of the spheroidized graphite particles, and is 0.1 to 1 with respect to 100% by weight of the composite carbon particles (B). It is preferably 10% by weight. Within this range, it can contribute to the improvement of the input / output characteristics of alkaline ions such as lithium ions. The coverage is more preferably 0.2 to 8% by weight, still more preferably 0.4 to 5% by weight. The coverage is represented by the weight% of the carbon layer existing on the surface of the spheroidized graphite particles, and the coverage can be measured by the method described later in the examples.

When the carbon layer is amorphous carbon, the coverage is preferably 0.1 to 10% by weight, more preferably 0.2 to 8% by weight, still more preferably 0.4 to 5% by weight. By setting the coverage of the carbon layer made of amorphous carbon to 0.1% by weight or more, the high acceptability of alkaline ions such as lithium ions contained in amorphous carbon can be fully utilized. By setting the coverage to 10% by weight or less, it is possible to prevent the capacity from decreasing due to the influence of the size of the irreversible capacity of the amorphous carbon, and to suppress the increase in contact resistance due to the carbon layer made of amorphous carbon. However, the rate characteristics can be improved.

<Physical characteristics>
(Circularity)
The composite carbon particles (B) of the present invention have a circularity of 0.89 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 (B) having a high circularity as described above, the initial efficiency can be improved. From the viewpoint of initial efficiency, the circularity of the composite carbon particles (B) is preferably 0.89 or more, more preferably 0.90 or more, further preferably 0.91 or more, and particularly preferably 0. It is .93 or more. The upper limit of the circularity of the composite carbon particles (B) is not particularly limited, but usually, since the theoretical upper limit is 1, the upper limit is less than 1.

The method for improving the circularity of the composite carbon particles (B) is not particularly limited, but a sphere-shaped composite carbon particle (B) 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.

(Average particle size (d50))
The average particle size (particle size of the 50% integrated portion from the small particle side in the volume particle size distribution) (d50) of the composite carbon particles (B) of the present invention is preferably 5 μm or more and 30 μm or less. When the average particle size of the composite carbon particles (B) is in this range, the increase in negative reversible capacity and the resistance at the contact interface due to the increase in the specific surface area due to the smaller particle size are suppressed, and the larger particle size is used. 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 composite carbon particles (B) is more preferably 8 to 27 μm, still more preferably 10 to 25 μm, and particularly preferably 12 to 23 μm.

The ratio R of the average particle diameter d50 of the silicon oxide particles (A) of the present invention to the average particle diameter d50 of the composite carbon particles (B) of the present invention is preferably in the above-mentioned preferable range.

In the volume particle size distribution of the composite carbon particles (B) of the present invention, the particle size (d10) of the 10% integrating portion from the small particle side is preferably 1 μm or more and 20 μm or less. When d10 is 1 μm or more, process inconvenience such as an increase in slurry viscosity can be prevented, a decrease in electrode strength and a decrease in initial charge / discharge efficiency can be prevented, and when d10 is 20 μm or less, high current density charge / discharge characteristics of the battery can be prevented. It is possible to prevent the deterioration of the low temperature input / output characteristics and the deterioration of the low temperature input / output characteristics. The d10 of the composite carbon particles (B) is more preferably 3 to 17 μm, still more preferably 5 to 15 μm, and particularly preferably 6 to 13 μm.

In the volume particle size distribution of the composite carbon particles (B) of the present invention, the particle size (d90) of the 90% integrating portion from the small particle side is preferably 10 μm or more and 100 μm or less. When d90 is 10 μm or more, it is possible to prevent a decrease in negative electrode strength and a decrease in initial charge / discharge efficiency. It is possible to prevent deterioration and deterioration of low temperature input / output characteristics. The d90 of the composite carbon particles (B) is more preferably 15 to 60 μm, still more preferably 17 to 40 μm, and particularly preferably 20 to 30 μm.

(aspect ratio)
The aspect ratio, which is the ratio of the length of the major axis to the minor axis of the composite carbon particles (B) of the present invention, is preferably 2.09 or less, more preferably 1.9 or less, still more preferably 1.8 or less, and particularly preferably. Is 1.7 or less. When the aspect ratio is in this range, the particle shape becomes elliptical or nearly spherical, and when used as an electrode, the continuity of the voids between the particles is ensured, the mobility of lithium ions is enhanced, and rapid charge / discharge characteristics are achieved. Shows excellent trends. If the aspect ratio is too large, the particle shape will be disk-shaped or plate-shaped instead of spherical or elliptical, and will be close to scaly graphite, and the voids between the particles will be bent, such as lithium ions. The mobility of alkali ions is poor, and the rapid charge / discharge characteristics tend to be inferior. The aspect ratio is the ratio of the length of the major axis to the minor axis of the particle, and the minimum value is 1, so the lower limit of the aspect ratio is usually 1. The aspect ratio of the composite carbon particles (B) can be measured by using the method of Examples described later.

(Tap density)
The tap density of the composite carbon particles (B) of the present invention is preferably 0.8 g / cm ³ or more, more preferably 0.9 g / cm ³ or more, still more preferably 1.00 g / cm ³ or more, and particularly preferably 1. .05g / cm ³ or more, and most preferably 1.08 g / cm ³ or more. The fact that the tap density is 0.8 g / cm ³ or more indicates that the composite carbon particles (B) are substantially spherical and that the internal structure of the composite carbon particles (B) is dense and there are few voids in the particles. .. When the tap density of the composite carbon particles (B) is 0.8 g / cm ³ or more, a suitable gap is formed in which the electrolytic solution and the composite carbon particles (B) can be present when used as an electrode. Can be done. Further, a path for a diffusion path of alkaline ions such as lithium ions in the electrode plate is formed, and sufficient alkaline ions such as lithium ions enter and exit the silicon oxide particles (A) and the composite carbon particles (B) during charging and discharging. Can be secured, and high capacity and high rate can be realized. The tap density is measured by the method of Examples described later.

(Specific surface area)
The specific surface area of the composite carbon particles (B) 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. The above is particularly preferably 4 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 7 m 2} / g or less, and particularly preferably 6.5 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.

(Surface spacing of 002 planes (d002) and crystallite size (Lc))
In the composite carbon particles (B) 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 (B) 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 (B) is 0.335 nm, it is usually 0.335 nm or more.

The crystallite size (Lc) of the composite carbon particles (B) 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 of the intensity IA of a peak PA around 1580 cm ^-1 in the Raman spectrum obtained by Raman spectroscopy, when measuring the intensity IB of the peak PB around 1360 cm ^-1, the intensity ratio R (R = Defined as IB / IA). Incidentally, the scope of 1580～1620Cm ^-1 A "1580cm around ^-1", the "1360cm around ^-1" refers to the range of 1350 ^-1.

The Raman R value of the composite carbon particles (B) of the present invention is usually 0.01 or more, preferably 0.05 or more, more preferably 0.10 or more, still more preferably 0.20 or more. Further, it is usually 1.00 or less, preferably 0.70 or less, more preferably 0.40 or less, still more preferably 0.37 or less, and particularly preferably 0.36 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 (B) of the present invention. In the composite carbon particles (B), 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 of the graphite particles due to excessive mechanical energy treatment is fine. 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 ion battery. The initial charge / discharge efficiency of the next 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 an argon ion laser beam, the measurement cell is rotated in a plane perpendicular to the laser beam. 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 by the mercury intrusion method of the composite carbon particles (B) of the present invention is preferably 0.01 ml / g or more, more preferably 0.05 ml / g or more. It is more preferably 0.1 ml / g or more. By setting the pore capacity to 0.01 ml / g or more, the area of entry and exit of alkaline ions such as lithium ions becomes large.

(The interplanar spacing of 002 surfaces of the spheroidized graphite particles before the carbon layer is provided (d002))
The surface spacing (d002) of the 002 planes of the spheroidized graphite particles used as the core of the composite carbon particles (B) of the present invention by the X-ray diffraction method is preferably 3.37 Å or less and Lc of 900 Å or more. The fact that the surface spacing (d002) of the 002 planes by the X-ray wide-angle diffraction method is 3.37 Å or less and Lc is 900 Å or more means that the surface of the composite carbon particles (B) in which the carbon layer made of amorphous carbon is present is present. The fact that most of the parts except the ones have high crystallinity indicates that the carbon material is a high-capacity electrode that does not cause a decrease in capacity due to a large irreversible capacity as seen in amorphous carbon materials. When the carbon layer of the composite carbon particles (B) is formed of a graphite material, the graphite material constituting the carbon layer also has a plane spacing (d002) of 002 planes by the X-ray diffractometry, and Lc is a nucleus. It is preferable to show the same value as the graphite particles used as.

(Tap density of spheroidized graphite particles before providing a carbon layer)
The tap density of the graphite particles used as the core of the composite carbon particles (B) of the present invention ^{is preferably 0.8 g / cm 3} or more. By setting the tap density of the graphite particles before having the carbon layer to 0.8 g / cm ³ or more, it is possible to obtain a carbon material having a high capacity and having fast discharge characteristics.

(Amorphous carbon 002 surface spacing (d002))
It is preferable that the surface spacing (d002) of the 002 planes of the amorphous carbon forming the carbon layer of the composite carbon particles (B) of the present invention by the X-ray wide-angle diffraction method is 3.40 Å or more and Lc is 500 Å or less. .. By setting the surface spacing (d002) of the 002 surfaces to 3.40 Å or more and Lc to 500 Å or less, the acceptability of lithium ions can be improved.

(True density)
The true density of the composite carbon particles (B) of the present invention ^{is preferably 2.1 g / cm 3} or more, more preferably 2.15 g / cm ³ or more, and 2.2 g / cm ³ or more. Is more preferable. The fact that the true density is 2.1 g / cm ³ or more indicates that the spherical graphite, which is the core of the composite carbon particles (B), has high crystallinity, and the irreversible capacity is small and the capacity can be increased. can. The true density is measured by the method of Examples described later.

<Manufacturing method of composite carbon particles (B)>
The composite carbon particles (B) of the present invention may be produced by any manufacturing method as long as they have the above-mentioned properties. For example, the carbon material for electrodes described in Japanese Patent No. 3534391 may be used. Can be done. Specifically, as the graphite particles before the carbon layer is provided, for example, scaly, lumpy or plate-shaped natural graphite, petroleum coke, coal pitch coke, coal needle coke, mesophase pitch and the like are heated to 2500 ° C. or higher. Can be manufactured. It is preferable to apply mechanical energy treatment to the graphite obtained by heating.

For mechanical energy treatment, for example, a device having a rotor having a large number of blades installed inside the casing is used, and the rotor is rotated at high speed to impact-compress the natural graphite or artificial graphite introduced inside the rotor. It can be manufactured by repeatedly applying mechanical actions such as friction and shearing force.

The composite carbon particles (B) are made by mixing graphite particles with petroleum-based or coal-based tar or pitch, polyvinyl alcohol, polyacrylic nitrile, phenol resin, cellulose or other resin, if necessary, using a solvent or the like to create a non-oxidizing atmosphere. By firing at 500 ° C. to 3000 ° C., preferably 700 ° C. to 2000 ° C., more preferably 800 ° C. to 1500 ° C., composite carbonaceous particles having a carbon layer made of amorphous carbon (for example, amorphous). (Carbon-coated graphite) and composite carbonaceous particles (for example, graphite-coated graphite) having a carbon layer made of graphite on at least a part of the surface of the graphite particles can be obtained. After firing the graphite particles, pulverization and classification can be performed if necessary.

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

<Physical characteristics>
<Average particle size (d50)>
The negative electrode material of the present invention preferably has an average particle size (particle size of 50% integrated portion from the small particle side in the volume particle size distribution) (d50) of 3 μm or more and 30 μm or less. When the average particle size (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 8 to 27 μm, more preferably 10 to 25 μm, and particularly preferably 12 to 23 μm.

(Tap density)
The tap density of the negative electrode material of the present invention is preferably 0.8~1.8g / cm ^3, more preferably 0.9~1.7g / cm ^3, more preferably 1.0~1.6g · cm ³ Is. When the tap density is within the above range, the electrolytic solution and the silicon oxide particles (A) can be present in the gaps formed by the composite carbon particles (B) 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 8 m 2} / g or less, and particularly preferably 6.5 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 hydrides thereof; syndiotactic-1,2-polybutadiene, ethylene. Soft resinous polymers such as vinyl acetate copolymers and copolymers of ethylene and α-olefins with 3 to 12 carbon atoms; polytetrafluoroethylene / ethylene copolymers, polyvinylidene fluoride, 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. Density of the active material layer is preferably in the range of 1.2~1.8g / cm ^3, more preferably 1.3~1.6g / cm ^3.

By setting the density of the active material layer to 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 (A) present in the gaps formed by the composite carbon particles (B). The presence of the silicon oxide particles (A) in the gaps formed by the composite carbon particles (B) 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.} lithium transition metal composite oxides such as lithium manganese composite oxide represented by ₂ and LiMn ₂ O _4, transition metal oxides such as manganese dioxide, and may be used these composite oxides mixtures. 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 in which a binder resin is mixed 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 containing the electrolyte 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-butylolactone. , 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 silicon oxide particles (A), composite carbon 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 Seisakusho).

<Tap density>
The measurement was performed using a powder density measuring instrument Tap Densor KYT-3000 (manufactured by Seishin Enterprise Co., Ltd.). 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 was measured by the equivalent circle diameter 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 an argon ion laser beam, the measurement cell is rotated in a plane perpendicular to the laser beam. 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 in this measurement, the intensity _{I A} of the peak PA around 1580 cm ^-1, when measured an intensity _{I B} of a peak _{P B} in the vicinity of 1360 cm ^-1, the intensity ratio R (R = It was defined as _{I B} / I _A). Incidentally, the scope of 1580～1620Cm ^-1 A "1580cm around ^-1", the "1360cm around ^-1" refers to the range of 1350 ^-1.

[Battery evaluation]
<Manufacturing of negative electrode for performance evaluation>
92.5% by weight of a mixture of composite carbon particles (B) and silicon oxide particles (A) described later, 5% by weight of acetylene black, 1% by weight of carboxymethyl cellulose (CMC) as a binder, and styrene-butadiene rubber (SBR). 48% by weight 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)>
The negative electrode for evaluation produced by the above method and the counter electrode obtained by punching a lithium metal foil into a disk shape having a diameter of 15 mm were used. _{Between the two poles, an electrolytic solution in which LiPF 6} was dissolved at 1 mol / L in a mixed solvent of ethylene carbonate, ethylmethyl carbonate and fluoroethylene carbonate (volume ratio = 3: 6: 1) was impregnated. A separator (made of porous polyethylene film) was placed to prepare a coin-shaped battery for performance evaluation.

<Charging capacity, discharging capacity, efficiency>
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.
It is charged to 5 mV with respect to the lithium counter electrode with a current density of 0.05 C, further charged with a constant voltage of 5 mV until the current density reaches 0.005 C, and after doping lithium into the negative electrode, the current density is 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 obtained 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 (%).

[Composite carbon particles (B)]
<Composite carbon particles (B1)>
Fragment-like natural graphite having a d50 of 100 μm was spheroidized by mechanical action for 10 minutes at a rotor peripheral speed of 80 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 16.3 μm. The obtained spherical graphite particles are mixed with petroleum-based heavy oil obtained at the time of thermal decomposition of naphtha as a carbonaceous substance precursor, heat-treated at 1300 ° C. in an inert gas, and then the calcined product is crushed and classified. Obtained composite carbon particles (B1) in which amorphous carbon was impregnated on the surface of the graphitic particles.

From the firing yield, in the obtained composite carbon particles (B1), the weight ratio of the spherical graphite particles to the amorphous carbon ([weight of spherical graphite particles]: [weight of amorphous carbon]) is 1. : It was confirmed that it was 0.04. The d50, d90, d10, tap density, specific surface area, circularity, and Raman R value were measured by the above-mentioned measuring method. The results are shown in Table 1.

<Composite carbon particles (B2)>
Fragment-like natural graphite having a d50 of 100 μm was spheroidized by mechanical action for 10 minutes at a rotor peripheral speed of 80 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 having a d50 of 10.6 μm. The obtained spherical graphite particles are mixed with petroleum-based heavy oil obtained at the time of thermal decomposition of naphtha as a carbonaceous substance precursor, heat-treated at 1300 ° C. in an inert gas, and then the calcined product is crushed and classified. Obtained composite carbon particles (B2) in which amorphous carbon was impregnated on the surface of the graphitic particles.

From the firing yield, in the obtained composite carbon particles (B2), the weight ratio of the spherical graphite particles to the amorphous carbon ([weight of spherical graphite particles]: [weight of amorphous carbon]) is 1. : It was confirmed that it was 0.07. The d50, d90, d10, tap density, specific surface area, circularity, and Raman R value were measured by the above-mentioned measuring method. The results are shown in Table 1.

<Composite carbon particles (b1)>
Fragment-like natural graphite having a d50 of 100 μm was spheroidized by mechanical action for 10 minutes at a rotor peripheral speed of 80 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 having a d50 of 9.8 μm. The obtained spherical graphite particles are mixed with petroleum-based heavy oil obtained at the time of thermal decomposition of naphtha as a carbonaceous substance precursor, heat-treated at 1300 ° C. in an inert gas, and then the calcined product is crushed and classified. Obtained composite carbon particles (b1) in which amorphous carbon was impregnated on the surface of the graphitic particles.

From the firing yield, in the obtained composite carbon particles (b1), the weight ratio of the spherical graphite particles to the amorphous carbon ([weight of spherical graphite particles]: [weight of amorphous carbon]) is 1. : It was confirmed that it was 0.08. The d50, d90, d10, tap density, specific surface area, circularity, and Raman R value were measured by the above-mentioned measuring method. The results are shown in Table 1.

<Silicon oxide particles (A1)>
Commercially available silicon oxide particles (SiOx, x = 1) (manufactured by Osaka Titanium Technologies Co., Ltd.) were heat-treated at 1000 ° C. for 6 hours in an inert atmosphere to obtain silicon oxide particles (A1). The silicon oxide particles (A1) 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 (A1), it is possible to confirm the diffraction line attributed to Si (111) near 2θ = 28.4 °, and the silicon oxide particles (A1) 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 line was 3.2 nm.

Table 2 shows the physical characteristics of the silicon oxide particles (A1).

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

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

[Comparative Example 1]
10 parts by weight of silicon oxide particles (A1) was dry-mixed with 90 parts by weight of graphite particles (b1) to prepare a mixture. The same evaluation as in Example 1 was performed.

Table 3 shows d50, d90, d10, and the specific surface area 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 excellent initial efficiency.

Claims (8)

It contains silicon oxide particles (A) and composite carbon particles (B), and the silicon oxide particles (A) contain zero-valent silicon atoms, and 10% integration from the small particle side of the silicon oxide particles (A). The particle size (d10) of the part is 0.001 μm or more and 6 μm or less, and the composite carbon particles (B) have a carbon layer on at least a part of the surface of the spherical graphite particles, which is obtained by flow-type particle image analysis. A carbon material for the negative electrode of a non-aqueous secondary battery having a circularity of 0.89 or more. The negative electrode material for a non-aqueous secondary battery according to claim 1, wherein the silicon oxide particles (A) contain microcrystals of silicon. The ratio of the silicon oxide particles (A) in the number of silicon atoms _{(M Si)} to the number of oxygen atoms _{(M O) (M O /} M Si) is 0.5 to 1.6, according to claim 1 or 2 Negative material for non-aqueous secondary batteries. The negative electrode material for a non-aqueous secondary battery according to any one of claims 1 to 3, wherein the composite carbonaceous particles (B) contain graphite obtained by spheroidizing natural graphite in the form of scales, scales, or lumps. 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 (A) is 0.01 μm or more and 20 μm or less. Average particle size ratio of silicon oxide particles (A) and composite carbonaceous particles (B) (R = [average particle size of silicon oxide particles (A) (d50)] / [average particles of composite carbonaceous particles (B)] The negative electrode material for a non-aqueous secondary battery according to any one of claims 1 to 5 , wherein the diameter (d50)]) is 0.001 or more and 10 or less. 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 6. 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 7 .