JP2018088404A - Anode material for nonaqueous secondary battery, anode for nonaqueous secondary battery, and nonaqueous secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an anode material for a nonaqueous secondary battery that has a high capacity and is excellent in initial efficiency, and an anode for a nonaqueous secondary battery and a nonaqueous secondary battery using the same.SOLUTION: A carbon material for an anode of a nonaqueous secondary battery includes silicon oxide particles (A) and composite carbon particles (B), where the silicon oxide particle (A) includes zero-valent silicon atoms, and the composite carbon particle (B) has a carbon layer on at least part of the surface of a sphered graphite particle, and has a circularity obtained through flow-type particle image analysis of 0.89 or more.SELECTED DRAWING: None

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 same, and a non-aqueous secondary battery including the negative electrode.

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

  Various negative electrode materials for this non-aqueous lithium secondary battery have been proposed, but currently, negative electrode materials using carbon materials are widely used. On the other hand, in order to dramatically improve the performance from the viewpoint of increasing the capacity, developments other than carbon materials are also underway, and one of representative examples is silicon and amorphous silicon oxide (SiOx). .

  As a negative electrode active material for a lithium ion secondary battery, silicon and amorphous silicon oxide (amorphous silicon oxide) are advantageous in that they have a large capacity, but they have a large deterioration when repeatedly charged and discharged. However, since the cycle characteristics are inferior and the initial efficiency is particularly low, practical use has not been achieved except for a part. As a solution to such problems, Patent Documents 1 and 2 use a silicon compound having a domain structure in which silicon microcrystals are dispersed in a silicon compound (particularly silicon oxide) as a negative electrode material. It is disclosed.

Japanese Patent Laid-Open No. 2004-047404 JP 2004-323284 A

In Patent Documents 1 and 2, a silicon-based compound having a domain structure in which silicon microcrystals are dispersed in a silicon-based compound (particularly silicon oxide) is converted into silicon and amorphous silicon oxide (amorphous silicon oxide). On the other hand, it is described that it is excellent in cycle characteristics and initial efficiency when repeatedly charged and discharged, and that a carbon material is used as a negative electrode material in combination as a conductive material. The negative electrode materials of Patent Documents 1 and 2 have found a problem that the balance between discharge capacity and initial efficiency is insufficient.
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 same. is there.

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

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

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

[3] The ratio (M _O / M _Si ) of the number of oxygen atoms (M _O ) to the number of silicon atoms (M _Si ) in the silicon oxide particles (A) is 0.5 to 1.6 [1] or [ 2] The negative electrode material for non-aqueous secondary batteries described in [2].

[4] The negative electrode for a non-aqueous secondary battery according to any one of [1] to [3], wherein the composite carbonaceous particle (B) includes graphite obtained by spheroidizing scaly, scaly, and massive natural graphite. Wood.

[5] The negative electrode material for a nonaqueous 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 a particle diameter (d10) of a 10% integration part from the small particle side of the silicon oxide particles (A) is 0.001 μm or more and 6 μm or less. Secondary battery negative electrode material.

[7] Average particle diameter ratio between silicon oxide particles (A) and composite carbonaceous particles (B) (R = [average particle diameter of silicon oxide particles (A) (d50)] / [composite carbonaceous particles (B) The average particle diameter (d50)]) is 0.001 or more and 10 or less, The negative electrode material for nonaqueous secondary batteries according to any one of [1] to [6].

[8] A negative electrode for a non-aqueous secondary battery comprising a current collector and an active material layer formed on the current collector, wherein the active material layer is any one of [1] to [7] A negative electrode for a nonaqueous secondary battery, comprising the negative electrode material for a nonaqueous secondary battery described.

[9] A nonaqueous secondary battery comprising a positive electrode, a negative electrode, and an electrolyte, wherein the negative electrode is the negative electrode for a nonaqueous secondary battery according to [8].

  ADVANTAGE OF THE INVENTION According to this invention, the negative electrode material for non-aqueous secondary batteries which is high capacity | capacitance and was excellent in initial efficiency, the negative electrode for non-aqueous secondary batteries using this, and a non-aqueous secondary battery are provided.

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

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

[mechanism]
<Action mechanism based on silicon oxide particles (A)>
The negative electrode material of the present invention includes a silicon oxide particle (A) having a high capacity and a small volume change due to insertion / extraction of Li ions, so that the performance deterioration due to the loss of contact with the composite carbon particle (B). A small, high-capacity negative electrode material can be obtained.
In particular, the ratio (M _O / M _Si ) of the number of oxygen atoms (M _O ) to the number of silicon atoms (M _Si ) in the silicon oxide particles (A) of the present invention is 0.5 to 1.6, At the same time as the capacity, the volume change amount due to insertion and extraction of Li ions becomes close to the volume change amount of the carbonaceous particles, and it becomes possible to reduce the performance deterioration due to the loss of contact with the carbonaceous particles. .
In addition, since the silicon oxide particles (A) contain zero-valent silicon atoms, the potential range for storing and releasing Li ions becomes close to that of the composite carbon particles (B), and the volume change accompanying the insertion and release of Li ions. Occurs simultaneously with the composite carbon particles (B), so that the relative positional relationship at the interface 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.

<Action 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 can easily insert and desorb Li ions. In addition, since the carbon layer is included, the particles are hard and difficult to be deformed during electrode rolling, and the circularity of the particles is high. It is considered that a flow path through which the liquid moves is secured, the Li ion diffusion path is improved, and the input / output characteristics at low temperature, charge / discharge rate characteristics, electrodeposition resistance, and cycle characteristics are improved.

<Action mechanism by blending silicon oxide particles (A) and composite carbon particles (B)>
When the negative electrode material of the present invention is used to form a negative electrode, the composite carbon particles (B) that have a carbon layer in the negative electrode and are hard to be deformed because the particles are hard and have high circularity of the particles are formed. By making the silicon oxide particles (A) exist in the gaps between the large volume particles, the volume change of the silicon oxide particles (A) during charge / discharge can be absorbed by the gaps formed by the composite carbon particles (B). Thus, the disconnection of the conductive path is suppressed. As a result, it is considered that an excessive current can be prevented from flowing only in specific portions 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)]
<Configuration>
The silicon oxide particles (A) of the present invention contain zero-valent silicon atoms. Preferably, silicon oxide particles (A) contain silicon microcrystals.

The ratio (M _O / M _Si ) of the number of oxygen atoms (M _O ) to the number of silicon atoms (M _Si ) in the silicon oxide particles (A) of the present invention is preferably 0.5 to 1.6, More preferably, it is 0.7-1.3, Most preferably, it is 0.8-1.2. When M 2 _O / M 3 _Si is in the above range, the capacity is higher than that of the composite carbon particle (B) due to particles made of highly active amorphous silicon oxide in which alkaline ions such as Li ions easily enter and exit. And a high cycle retention ratio can be achieved by the amorphous structure. Further, the silicon oxide particles (A) are filled in the gaps formed by the composite carbon particles (B) while securing the contact points with the composite carbon particles (B), so that alkali ions such as Li ions are occluded by charge / discharge. -The volume change of the silicon oxide particles (A) accompanying the release can be absorbed by the gap. As a result, it is possible to suppress the conduction path interruption due to the volume change of the silicon oxide particles (A).

The silicon oxide particles (A) containing a zero-valent silicon atom usually have a peak of −100 to −120 ppm, especially in the vicinity of −110 ppm present in silicon oxide in solid state NMR ( ²⁹ Si-DDMAS) measurement. In addition to the broad peak (P1) in the range, it is preferable that there is a broad peak (P2) centered at -70 ppm, and in particular the peak apex 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. A range of 8 is more preferable. When the silicon oxide particles (A) containing zero-valent silicon atoms have the above properties, a negative electrode material having a large capacity and high cycle characteristics can be obtained.

  Moreover, it is preferable that the silicon oxide particles (A) containing zero-valent silicon atoms generate hydrogen when an alkali hydroxide is allowed to act thereon. 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. More preferably, it is about -30 wt%. If the amount of zero-valent silicon atoms is less than 2% by weight, the charge / discharge capacity may be reduced, and if it exceeds 45% by weight, the cycle characteristics may be inferior.

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

i. In X-ray diffraction (Cu-Kα) using copper as the counter-cathode, a diffraction peak attributed to Si (111) centered around 2θ = 28.4 ° is observed, and based on the broadening of the diffraction line The particle diameter of the silicon crystal determined by the Scherrer equation is preferably 1 to 500 nm, more preferably 2 to 200 nm, and still more preferably 2 to 20 nm. If the size of the silicon fine particles is smaller than 1 nm, the charge / discharge capacity may be reduced. Conversely, if the silicon fine particle is larger than 500 nm, the expansion / contraction during charge / discharge increases, and the cycle performance may decrease. The size of the silicon fine particles can be measured by a transmission electron micrograph.

ii. In solid-state NMR ( ²⁹ Si-DDMAS) measurement, there is a peak characteristic of Si diamond crystals in the vicinity of −84 ppm, along with a broad silicon dioxide peak whose spectrum is centered around −110 ppm. This spectrum is completely different from normal silicon oxide (SiOx, x = 1.0 + α), and the structure itself is clearly different. Further, it is confirmed by transmission electron microscope 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 still more preferably about 10 to 30% by weight. If the amount of microcrystals of silicon is less than 2% by weight, the charge / discharge capacity may be small, and if it exceeds 45% by weight, the cycle performance may be inferior.

<Physical properties>
(Average particle diameter (d50))
The average particle diameter of the silicon oxide particles (A) of the present invention (particle diameter of 50% integration part from the small particle side in the volume particle size distribution) (d50) is preferably 0.1 μm or more and 20 μm or less. If the d50 of the silicon oxide particles (A) is within the above range, the silicon oxide particles (A) are present in the gaps formed by the composite carbon particles (B) in the case of an electrode, and an alkali such as Li ion due to charge / discharge. The gap absorbs the volume change of the silicon oxide particles (A) accompanying the occlusion / release of ions, and the conduction path cut due to the volume change is suppressed, 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, further 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 diameter (d10) of the 10% integration part 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 within the above range and an appropriate fine powder exists, the silicon oxide particles (A) existing in the gaps between the composite carbon particles (B) can take a good conductive path. In addition, the cycle characteristics can be improved, and the increase in the specific surface area can be suppressed to reduce the irreversible capacity. D10 of the silicon oxide particles (A) is more preferably 0.01 to 4 μm, and further preferably 0.1 to 3 μm.

  In the volume particle size distribution of the silicon oxide particles (A) of the present invention, the particle diameter (d90) of the 90% integration part 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 be present in the gaps between the composite carbon particles (B), a good conductive path can be taken, and the cycle characteristics are good. The d90 of the silicon oxide particles (A) is more preferably 1.5 to 30 μm, further preferably 2 to 20 μm, and particularly preferably 3 to 10 μm.

<Average particle size ratio>
The average particle diameter of the silicon oxide particles (A) of the present invention (the particle diameter of the 50% cumulative portion from the small particle side in the volume particle size distribution) d50 and the average particle diameter of the composite carbon particles (B) of the present invention (in the volume particle size distribution) Ratio from the small particle side to 50% integrated part particle diameter) d50 (R = [average particle diameter of silicon oxide particles (A) (d50)] / [average particle diameter of composite carbonaceous particles (B) (d50) ]) Is preferably 0.001 or more and 10 or less.
When the average particle diameter ratio R is 0.001 or more, an increase in specific surface area can be suppressed and the irreversible capacity can be reduced. When the average particle diameter ratio R is 10 or less, silicon oxide particles are placed in the gaps between the composite carbon particles (B). (A) can be present, and the volume change of the silicon oxide particles (A) accompanying the occlusion / release of alkali ions such as Li ions due to charge / discharge is absorbed by the gap formed by the composite carbon particles (B). Therefore, it is possible to suppress the disconnection of the conductive path accompanying 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 from 0.01 to 3, more preferably from 0.1 to 1, particularly preferably from 0.15 to 0.8, most preferably from 0.2 to 0.6.

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

(Specific surface area)
The specific surface area by the BET method of the silicon oxide particles (A) of the present invention is preferably 80 m ² / g or less, and more preferably 60 m ² / g or less. Moreover, it is preferable that it is 0.5 m < ² > / g or more, It is more preferable that it is 1 m < ² > / g or more, It is still more preferable that it is 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 input / output efficiency of alkali ions such as lithium ions can be maintained well, and the silicon oxide particles (A) have a suitable size. And 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, an increase in irreversible capacity can be suppressed and a high capacity can be secured.
The specific surface area by the BET method is measured by the method described in the Examples section below.

<Method for producing silicon oxide particles (A)>
The silicon oxide particles are usually obtained by using silicon dioxide (SiO ₂ ) as a raw material and thermally reducing SiO ₂ using metallic silicon (Si) and / or carbon, and the value of x of SiOx is 0 <x < 2 is a general term for particles made of silicon oxide (however, as will be described later, it is possible to dope other elements other than silicon and carbon, and in this case, a composition formula different from SiOx and This is also included in the silicon oxide particles (A) used in the present invention.) Silicon (Si) has a larger theoretical capacity than that of graphite, and amorphous silicon oxide allows easy entry and exit of alkali ions such as lithium ions, so that a high capacity can be obtained.

  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 ( It can be produced by subjecting A1) or silicon oxide particles (A2) to a disproportionation treatment described later.

  The silicon oxide particles used for the disproportionation treatment when producing the silicon oxide particles (A) used in the present invention have a carbon layer made of amorphous carbon at least part of the surface with the silicon oxide particles as a nucleus. Alternatively, composite silicon oxide particles may be used. As the silicon oxide particles, one kind selected from the group consisting of silicon oxide particles (A1) not having a carbon layer made of amorphous carbon and composite silicon oxide particles (A2) may be used alone. Two or more kinds may be used in combination. Here, “having a carbon layer made of amorphous carbon on at least a part of the surface” means that the carbon layer covers not only a part or all of the surface of the silicon oxide particles in a layered manner, It includes forms that adhere to or adhere to part or all of the surface. The carbon layer may be provided so as to cover the entire surface, or a part of the carbon layer may be coated, attached, or attached.

<Method for producing silicon oxide particles (A1)>
Although the manufacturing method of the silicon oxide particles (A1) is not limited, for example, silicon oxide particles manufactured by a method described in Japanese Patent No. 3952118 can be used. Specifically, silicon dioxide powder and metal silicon powder or carbon powder are mixed at a specific ratio, and after the mixture is charged into the reactor, the pressure is reduced to normal pressure or a specific pressure, and the temperature is increased to 1000 ° C. or higher. The silicon oxide particles represented by the general formula SiOx (x is 0.5 ≦ x ≦ 1.6) can be obtained by heating and holding to generate SiOx gas and cooling and depositing. The precipitate can be made into particles by applying mechanical energy treatment.

  For mechanical energy treatment, for example, using a device such as a ball mill, a vibrating ball mill, a planetary ball mill, or a rolling ball mill, a raw material charged in the reactor and a moving body that does not react with the raw material are placed, and this is vibrated and rotated. Alternatively, the silicon oxide particles (A) satisfying the above physical properties can be formed by a method that gives a combined movement.

<Method for Producing Composite Type Silicon Oxide Particles (A2)>
There is no particular limitation on the method of 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. After mixing a resin such as tar or pitch of a system or coal, polyvinyl alcohol, polyacrylonitrile, phenol resin, cellulose, etc., if necessary using a solvent or the like, 500 to 3000 ° C., preferably 700 ° C. in a non-oxidizing atmosphere By firing at ˜2000 ° C., more preferably 800-1500 ° C., composite type 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 subjecting the silicon oxide particles (A1) and composite silicon oxide particles (A2) produced as described above to further heat treatment and disproportionation treatment. By performing disproportionation treatment, a structure in which zero-valent silicon atoms are unevenly distributed as Si fine crystals in amorphous SiOx is formed, and the negative electrode of the present invention is formed by such Si fine crystals in amorphous SiOx. As described in the material mechanism section, the potential range for storing and releasing Li ions is close to that of the composite carbon particles (B), and the volume change accompanying the storage and release of Li ions is simultaneous with the composite carbon particles (B). As a result, the relative positional relationship at the interface between the composite carbon particles (B) and the silicon oxide particles (A) is maintained, and the performance deterioration due to the loss of contact with the composite carbon particles (B) is reduced. Theft is possible.

  This disproportionation treatment can be performed by heating the aforementioned silicon oxide particles (A1) or composite silicon oxide particles (A2) in an inert gas atmosphere in the temperature range of 900 to 1400 ° C. .

  If the heat treatment temperature of the disproportionation treatment is lower than 900 ° C., disproportionation does not proceed at all or it takes a very long time to form fine silicon cells (silicon microcrystals), which is not efficient and conversely When the temperature is higher than 1400 ° C., the structure of the silicon dioxide portion is advanced and the traffic of Li ions is hindered, so that the function as a lithium ion secondary battery may be deteriorated. The heat treatment temperature of 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 about 10 minutes to 20 hours, particularly about 30 minutes to 12 hours, depending on the disproportionation treatment temperature. For example, at a treatment temperature of 1100 ° C. Is preferably about 5 hours.

The disproportionation treatment is not particularly limited as long as a reaction apparatus having a heating mechanism is used in an inert gas atmosphere, and treatment by a continuous method or a batch method is possible, specifically a fluidized bed reaction. A furnace, a rotary furnace, a vertical moving bed reaction furnace, a tunnel furnace, a batch furnace, a rotary kiln, and the like can be appropriately selected according to the purpose. In this case, as the (treatment) gas, an inert gas alone or a mixed gas thereof such as Ar, He, H ₂ , and N ₂ can be used.

<Production of carbon coating / silicon microcrystal dispersed silicon oxide particles>
The silicon oxide particles (A) of the present invention are, as described below, subjected to carbon coating and disproportionation treatment simultaneously as composite silicon oxide particles in which the surface of silicon oxide particles containing silicon microcrystals is coated with carbon. 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 suitably employed.
I: Using silicon oxide powder represented by the general formula SiOx (0.5 ≦ x <1.6) as a raw material, in an atmosphere containing at least organic gas and / or steam, 900 to 1400 ° C., preferably 1000 to 1400 ° C., More preferably, heat treatment is performed at a temperature range of 1050 to 1300 ° C., more preferably 1100 to 1200 ° C., thereby disproportionating the raw silicon oxide powder into a composite of silicon and silicon dioxide, and chemical vapor deposition of the surface thereof. Method II: Silicon oxide powder represented by the general formula SiOx (0.5 ≦ x <1.6) is preliminarily 900 to 1400 ° C., preferably 1000 to 1400 ° C., more preferably 1100 to 1300 ° C. in an inert gas atmosphere. A silicon composite that is disproportionated by heat treatment, a composite in which silicon fine particles are coated with silicon dioxide by the sol-gel method, silicon A composite obtained by sintering a powder obtained by coagulating fine powdered silica such as fumed silica, precipitated silica and water, or silicon and its partial oxide or nitride, preferably 0.1 What was pulverized to a particle size of ˜50 μm in advance and heated at 800 to 1400 ° C. in an inert gas stream, and at least 800 to 1400 ° C., preferably 900 to 1300 in an atmosphere containing at least organic gas and / or steam. Method III of chemically vapor-depositing the surface by heat treatment in a temperature range of 1000 ° C., more preferably 1000 to 1200 ° C .: Silicon oxide powder represented by the general formula SiOx (0.5 ≦ x <1.6) is preliminarily 500 to 1200 The raw material is a material subjected to chemical vapor deposition treatment with an organic gas and / or vapor in a temperature range of 500 ° C., preferably 500 to 1000 ° C., more preferably 500 to 900 ° C. A method of performing disproportionation by performing a heat treatment in a temperature range of 900 to 1400 ° C., preferably 1000 to 1400 ° C., more preferably 1100 to 1300 ° C. in an inert gas atmosphere.

  In the chemical vapor deposition process (that is, thermal CVD process) 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, when the heat treatment temperature is lower than 800 ° C. , Fusion of conductive carbon film and silicon composite, alignment of carbon atoms (crystallization) is insufficient, and conversely, when the temperature is higher than 1400 ° C., the structure of the silicon dioxide part is advanced and the passage of lithium ions is inhibited. Therefore, the function as a lithium ion secondary battery may be reduced.

  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., disproportionation does not proceed at all or it is extremely long for the formation of fine silicon cells (silicon microcrystals). If it takes time and is not efficient, and conversely higher than 1400 ° C., the structure of the silicon dioxide portion is advanced and the traffic of lithium ions is hindered, so the function as a lithium ion secondary battery may be reduced. is there.

  In the 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 formed by performing thermal CVD (chemical vapor deposition at 800 ° C. or higher), and the thermal CVD time is appropriately set in relation to the amount of carbon. In this treatment, particles may be aggregated, and the aggregate is crushed with a ball mill or the like. In some cases, thermal CVD is repeated again in the same manner.

  In the above method I, when silicon oxide represented by the general formula SiOx (0.5 ≦ x <1.6) is used as a raw material, a disproportionation reaction is performed simultaneously with the chemical vapor deposition treatment, It is important to finely disperse silicon having a crystal structure in silicon dioxide. In this case, the processing temperature, processing time, type of raw material for generating organic gas, and organic matter for proceeding chemical vapor deposition and disproportionation It is necessary to select the gas concentration appropriately. The heat treatment time ((CVD / disproportionation) time) is usually selected from the range of 0.5 to 12 hours, preferably 1 to 8 hours, particularly 2 to 6 hours. For example, when the treatment temperature is 1000 ° C., it is preferable to carry out the treatment for at least 5 hours or more.

  In the method II, the heat treatment time (CVD treatment time) when heat-treating in an atmosphere containing an organic gas and / or vapor is usually 0.5 to 12 hours, particularly 1 to 6 hours. Can do. In addition, the heat treatment time (disproportionation time) in the case of disproportionating the silicon oxide of SiOx in advance can be usually 0.5 to 6 hours, particularly 0.5 to 3 hours.

  Furthermore, in the above method III, the processing time (CVD processing time) in the case of chemical vapor deposition treatment of SiOx in advance can be usually 0.5 to 12 hours, particularly 1 to 6 hours, under an inert gas atmosphere. The heat treatment time (disproportionation time) in can usually be 0.5 to 6 hours, particularly 0.5 to 3 hours.

  As an organic substance used as a raw material for generating an organic gas, those capable of generating carbon (graphite) by pyrolysis at the above heat treatment temperature are selected, particularly in a non-oxidizing atmosphere. For example, methane, ethane, ethylene, acetylene , Propane, butane, butene, pentane, isobutane, hexane, etc. Examples thereof include monocyclic to tricyclic aromatic hydrocarbons such as indene, coumarone, pyridine, anthracene, phenanthrene, and mixtures thereof. Further, gas light oil, creosote oil, anthracene oil, and naphtha cracked tar oil obtained in the tar distillation step can be used alone or as a mixture.

The thermal CVD (thermochemical vapor deposition) and / or disproportionation may be performed using a reactor having a heating mechanism in a non-oxidizing atmosphere, and is not particularly limited. Specifically, a fluidized bed reaction furnace, a rotary furnace, a vertical moving bed reaction furnace, a tunnel furnace, a batch furnace, 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 , or N ₂ can be used.

  In this case, a reactor having a structure in which a furnace core tube such as a rotary furnace, a rotary kiln and the like is disposed in the horizontal direction and the furnace core tube rotates is preferable, thereby performing chemical vapor deposition while rolling silicon oxide particles. Stable production is possible without causing aggregation between the silicon oxide particles. The rotation speed of the furnace core tube is preferably 0.5 to 30 rpm, particularly 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 rotating machine groove for rotating the furnace core tube, and a heating mechanism capable of raising and maintaining the temperature. A raw material supply mechanism (for example, a feeder) and a product recovery mechanism (for example, a hopper) can be provided, and in order to control the residence time of the raw material, the furnace core tube can be inclined, or a baffle plate can be provided in the furnace core tube. The material of the furnace core tube is not particularly limited, and ceramics such as silicon carbide, alumina, mullite, and silicon nitride, refractory metals such as molybdenum and tungsten, SUS, and quartz are appropriately selected depending on the processing conditions and processing purpose. Can be used.

Further, the flow gas linear velocity u (m / sec) is more efficiently achieved by setting the ratio u / u _mf to the fluidization start velocity u _mf to be in a range where 1.5 ≦ u / u _mf ≦ 5. A conductive film can be formed. If u / u _mf is less than 1.5, fluidization may be insufficient and the conductive film may vary. If u / u _mf exceeds 5, conversely, secondary aggregation of particles occurs. In some cases, a uniform conductive film cannot be formed. Here, the fluidization start speed varies depending on the size of the particles, the processing temperature, the processing atmosphere, etc., and the fluidizing gas (linear velocity) is gradually increased, and the powder pressure loss at that time is W (powder weight) / It can be defined as the value of the fluidized gas linear velocity when A (fluidized bed cross-sectional area) is reached. _{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} The thickness may be preferably 5 to 50 μm. When the particle diameter is smaller than 0.5 μm, secondary aggregation occurs, and the surface of each particle may not be treated effectively.

<Doping of other elements into silicon oxide particles (A)>
The silicon oxide particles (A) may be doped with elements other than silicon and oxygen. The silicon oxide particles (A) doped with elements other than silicon and oxygen are expected to improve initial charge / discharge efficiency and cycle characteristics by stabilizing the chemical structure inside the particles. Further, since such silicon oxide particles (A) improve the 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) are combined. By using the negative electrode material included together, a lithium ion is not extremely concentrated in the negative electrode even during rapid charging, and a battery in which metallic lithium is difficult to deposit can be manufactured.

  The element to be doped can be selected from any elements as long as it is an element other than Group 18 of the periodic table, but silicon oxide particles (A) doped with an element other than silicon and oxygen are more stable. The elements up to the fourth period of the periodic table are preferred. 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 fourth period of the periodic table. In order to improve the lithium ion acceptability of silicon oxide particles (A) doped with elements other than silicon and oxygen, the doped elements should be alkali metals and alkaline earth metals up to the fourth period of the periodic table. Is preferable, Mg, Ca, and Li are more preferable, and Li is still more preferable. These can be used alone or in combination of two or more.

The ratio of the number of atoms of the doped element (M _D ) to the number of silicon atoms (M _Si ) in the silicon oxide particles (A) doped with elements other than silicon and oxygen (M _D / M _Si ) is 0 .01 to 5 is preferable, 0.05 to 4 is more preferable, and 0.1 to 3 is still more preferable. Silicon If M D _/ M _Si is below this range, element doped effect other than oxygen can not be obtained, the surface of the silicon is not consumed in the doped reaction exceeds this range, elements other than oxygen silicon oxide particles May be a cause of lowering the capacity of the silicon oxide particles.

  Examples of a method for producing silicon oxide particles (A) doped with elements other than silicon and oxygen include, for example, mixing silicon oxide particles and a simple substance of a doped element or compound powder, and an inert gas atmosphere. Below, the method of heating at the temperature of 50-1200 degreeC is mentioned. Also, for example, silicon dioxide powder and metal silicon powder or carbon powder are mixed at a specific ratio, and a simple substance or compound powder of an element to be doped is added thereto, and this mixture is charged into a reactor. Thereafter, the pressure is reduced to normal pressure or a specific pressure, the temperature is raised to 1000 ° C. or higher, and the generated gas is cooled and precipitated to obtain silicon oxide particles doped with elements other than silicon and oxygen. It is done.

[Composite carbon particles (B)]
<Configuration>
The composite carbon particles (B) of the present invention are composite-type carbonaceous particles having a carbon layer on at least a part of the surface of the spheroidized graphite particles. Here, “the carbon layer is provided on at least a part of the surface” means that the carbon layer is not only in a form of covering part or all of the surface of the graphite particles in a layered manner, but also the carbon layer is attached to part or all of the surface.・ Includes the form of attachment. The carbon layer may be provided so as to cover the entire surface, or may be partially covered or attached / attached, but preferably the entire surface is covered. As such composite carbon particles (B), for example, composite type graphite (also referred to as “amorphous carbon-coated graphite”) having a carbon layer made of amorphous carbon on at least a part of the surface of spheroidized graphite particles. Or 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. 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 has a carbon layer on at least a part of the surface of the graphite particles, for example, it can also be confirmed by a TEM photograph or the like.

  Examples of the spheroidized graphite particles provided with a carbon layer include, for example, scale-like, massive or plate-like graphite, and petroleum coke, coal pitch coke, coal needle coke, and mesophase pitch heated to 2500 ° C. or higher. It is possible to use graphite particles formed into particles by applying mechanical energy treatment to artificial graphite produced in this manner. In the negative electrode material for a non-aqueous secondary battery, the carbon layer of the composite carbon particle (B) may be a graphite 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 present on the surface of the spheroidized graphite particles, and is 0.1 to 100% by weight of the composite carbon particles (B). It is preferably 10% by weight. If it is this range, it can contribute to the improvement of the input-output characteristic of alkali ions, such as lithium ion. The coverage is more preferably 0.2 to 8% by weight, and still more preferably 0.4 to 5% by weight. The coverage is expressed in terms of% by weight of the carbon layer present on the surface of the spheroidized graphite particles, and the coverage can be measured by the method described later in 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, and 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 alkali ions such as lithium ions possessed by amorphous carbon can be fully utilized. By setting the coverage to 10% by weight or less, it is possible to prevent a decrease in capacity due to the influence of the irreversible capacity of amorphous carbon, and to suppress an increase in contact resistance due to a carbon layer made of amorphous carbon. In addition, the rate characteristics can be improved.

<Physical properties>
(Roundness)
The composite carbon particles (B) of the present invention have a circularity of 0.89 or more determined by flow-type particle image analysis measured by the method described in the Examples section below. Thus, initial efficiency can be improved by using the composite carbon particle (B) with high circularity. 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, still more preferably 0.91 or more, and particularly preferably 0. .93 or more. The upper limit of the degree of circularity of the composite carbon particles (B) is not particularly limited. However, since the theoretical upper limit is usually 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 spherical shape obtained by applying a spheroidizing treatment is preferable because the shape of the interparticle voids when the electrode body is formed. Examples of spheroidizing methods include mechanically approaching a sphere by applying shearing force and compressive force, mechanical / physical processing method that granulates a plurality of fine particles by the adhesive force of the binder or the particles themselves, etc. Is mentioned.

(Average particle diameter (d50))
The composite carbon particles (B) of the present invention preferably have an average particle size (particle size of 50% cumulative portion from the small particle side in the volume particle size distribution) (d50) of 5 μm or more and 30 μm or less. If 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 specific surface area due to the reduction in the particle size are suppressed, It is possible to prevent a decrease in rapid charge / discharge performance due to a decrease in contact area between the electrolytic solution and the negative electrode material particles. The d50 of the composite carbon particles (B) is more preferably 8 to 27 μm, further preferably 10 to 25 μm, and particularly preferably 12 to 23 μm.

  The ratio R between the average particle diameter d50 of the silicon oxide particles (A) of the present invention and the average particle diameter d50 of the composite carbon particles (B) of the present invention is preferably within the above-mentioned preferred range.

  In the volume particle size distribution of the composite carbon particles (B) of the present invention, the particle diameter (d10) of the 10% integration part from the small particle side is preferably 1 μm or more and 20 μm or less. When d10 is 1 μm or more, it is possible to prevent the occurrence of process inconveniences such as an increase in slurry viscosity, a decrease in electrode strength and a decrease in initial charge / discharge efficiency, and when it is 20 μm or less, the high current density charge / discharge characteristics of the battery. And lowering of low temperature input / output characteristics can be prevented. The d10 of the composite carbon particles (B) is more preferably 3 to 17 μm, further 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 diameter (d90) of the 90% integration part 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. When d90 is 100 μm or less, process inconveniences such as line drawing occur, and high current density charge / discharge characteristics of the battery. It is possible to prevent a decrease and a decrease in 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 particle (B) of the present invention, is preferably 2.09 or less, more preferably 1.9 or less, still more preferably 1.8 or less, particularly preferably. Is 1.7 or less. If the aspect ratio is within this range, the particle shape will be almost elliptical or spherical, and when used as an electrode, the continuity of voids between particles will be ensured and the mobility of lithium ions will be improved, resulting in rapid charge / discharge characteristics. Shows excellent trend. If the aspect ratio is too large, the particle shape will not be spherical or elliptical, but will be disk-like or plate-like, close to scale-like graphite, and the voids between the particles will be bent, resulting in lithium ions, etc. The mobility of alkali ions is poor and the rapid charge / discharge characteristics tend to be poor. 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. Therefore, 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, particularly preferably 1 .05g / cm ³ or more, and most preferably 1.08 g / cm ³ or more. A tap density of 0.8 g / cm ³ or more indicates that the composite carbon particles (B) are almost spherical or 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 particle (B) is 0.8 g / cm ³ or more, when the electrode is used as an electrode, a suitable gap capable of allowing the electrolytic solution and the composite carbon particle (B) to exist is formed. Can do. In addition, a path of a diffusion path of alkali ions such as lithium ions in the electrode plate is formed, and sufficient alkali ions such as lithium ions enter and exit the silicon oxide particles (A) and composite carbon particles (B) during charging and discharging. Can be ensured, and higher capacity and higher rate can be realized. A tap density is measured by the method of the Example mentioned later.

(Specific surface area)
The specific surface area according to the BET method of the composite carbon particles (B) of the present invention is usually 0.5 m ² / g or more, preferably 1 m ² / g or more, more preferably 2 m ² / g or more, and further preferably 3 m ² / g. As described above, particularly preferably 4 m ² / g or more. Moreover, it is 30 m < ² > / g or less normally, Preferably it is 20 m < ² > / g or less, More preferably, it is 10 m < ² > / g or less, More preferably, it is 7 m < ² > / g or less, Especially preferably, it is 6.5 m < ² > / g or less. When the specific surface area is below this range, there are few sites where Li enters and exits, and the high-speed charge / discharge characteristic output characteristics and low-temperature input / output characteristics of the lithium ion secondary battery are inferior. On the other hand, when the specific surface area exceeds this range, the active material The activity with respect to the electrolytic solution becomes excessive, and an increase in the side reaction 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 Examples section below.

(Distance between 002 planes (d002) and crystallite size (Lc))
In the composite carbon particle (B) of the present invention, the interplanar spacing d value (interlayer distance (d002)) of the lattice plane (002 plane) 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 indicates that the composite carbon particles (B) have low crystallinity, and the initial irreversible capacity of the lithium ion secondary battery may increase. On the other hand, since the theoretical value of the interplanar spacing of the 002 plane of the composite carbon particle (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 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 be reduced. The lower limit is the theoretical value of graphite.
The measuring method of (d002) and (Lc) is as follows.

<d002 spacing, Lc>
The sample powder was mixed with about 15% by weight of X-ray standard high-purity silicon powder. The CuKα ray monochromatized with a graphite monochromator was used as the radiation source, and the wide-angle X was measured using the reflective diffractometer method. A line diffraction curve is measured. The interplanar spacing (d002) and crystallite size (Lc) are obtained 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 = 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, and further 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.

  When the Raman R value is too small, it means that sufficient damage is not given to the particle surface in the mechanical energy treatment such as graphite particles in the production process of the composite carbon particles (B) of the present invention. In the composite carbon particle (B), since the amount of accepting or releasing Li ions such as fine cracks and defects on the surface of the graphite particles due to damage, structural defects, etc. is small, in the lithium ion secondary battery, Li The rapid charge / discharge property of ions may deteriorate.

  Further, the large Raman R value means that, for example, the amount of amorphous carbon covering the graphite particles or the like is large, and / or the surface of the graphite particles or the like due to excessive mechanical energy treatment is fine. This indicates that the amount of cracks, defects, and structural defects is too large. If the Raman R value is too large, the influence of irreversible capacity of amorphous carbon increases, and side reactions with the electrolyte increase. The initial charge / discharge efficiency of the secondary battery is reduced and the amount of gas generated is increased, and the battery capacity tends to decrease.

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

(Pore volume)
The pore volume in the range of 10 nm to 100000 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, More preferably, it is 0.1 ml / g or more. By setting the pore volume to 0.01 ml / g or more, the area in and out of alkali ions such as lithium ions is increased.

(Distance between 002 faces of spheroidized graphite particles before having a carbon layer (d002))
The interplanar spacing (d002) of spheroidized graphite particles used as nuclei of the composite carbon particles (B) of the present invention by X-ray diffraction is preferably 3.37 mm or less and Lc is 900 mm or more. The interplanar spacing (d002) of the 002 plane measured by the X-ray wide angle diffraction method is 3.37 mm or less and Lc is 900 mm or more. This indicates that the surface of the composite carbon particle (B) where the carbon layer made of amorphous carbon exists is present. This means that the crystallinity of most of the parts except for it is high, which indicates that the carbon material is a high-capacity electrode that does not cause a reduction in capacity due to the large irreversible capacity found in amorphous carbon materials. When the carbon layer of the composite carbon particle (B) is formed of a graphite material, the graphite material constituting the carbon layer also has an 002 plane spacing (d002) by the X-ray diffraction method and Lc is a nucleus. It is preferable to show the same value as that of the graphite particles used as.

(Tap density of spheroidized graphite particles before having a carbon layer)
The tap density of the graphite particles used as the core of the composite carbon particle (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, a carbon material having high capacity and rapid discharge characteristics can be obtained.

(Amorphous carbon 002 plane spacing (d002))
It is preferable that the interplanar spacing (d002) of the amorphous carbon by the X-ray wide angle diffraction method (d002) forming the carbon layer of the composite carbon particle (B) of the present invention is 3.40 mm or more and Lc is 500 mm or less. . By setting the 002 plane spacing (d002) to 3.40 mm or more and Lc to 500 mm or less, the lithium ion acceptability 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. A true density of 2.1 g / cm ³ or higher indicates that the crystallinity of the spheroidized graphite serving as the core of the composite carbon particles (B) is high, and the irreversible capacity is small and the capacity can be increased. it can. A true density is measured by the method of the Example mentioned later.

<Method for producing composite carbon particle (B)>
The composite carbon particles (B) of the present invention can be produced by any manufacturing method as long as they have the above properties. For example, the carbon material for electrodes described in Japanese Patent No. 3534391 is used. Can do. Specifically, as graphite particles before having a carbon layer, for example, scaly, lump or plate-like natural graphite, petroleum coke, coal pitch coke, coal needle coke, and mesophase pitch are heated to 2500 ° C. or more. Can be manufactured. In addition, it is preferable to give mechanical energy processing to the graphite obtained by heating.

  Mechanical energy treatment is, for example, using an apparatus having a rotor with a large number of blades installed inside the casing, and rotating the rotor at a high speed to compress the impact on the natural graphite or artificial graphite introduced therein, It can be manufactured by repeatedly applying mechanical action such as friction and shearing force.

  The composite carbon particle (B) is a non-oxidizing atmosphere in which graphite particles are mixed with petroleum or coal-based tars and pitches, resins such as polyvinyl alcohol, polyacrylonitrile, phenolic resin, and cellulose, if necessary, using a solvent. At 500 ° C. to 3000 ° C., preferably 700 ° C. to 2000 ° C., and more preferably 800 to 1500 ° C., to obtain composite type carbonaceous particles (for example, amorphous) having a carbon layer made of amorphous carbon. Carbon-coated graphite) or 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. If necessary after calcination of the graphite particles, pulverization and classification can be performed.

[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) having a particle size distribution and physical properties suitable for the present invention and composite carbon particles (B) [weight of composite carbon particles (B)]: [silicon oxide particles] The weight of (A)] is preferably 30:70 to 99: 1, particularly 40:60 to 98: 3, and particularly preferably 50:50 to 95: 5, and silicon oxide particles (A ) And composite carbon particles (B) are mixed and used to form silicon oxide particles having a high capacity and a small volume change due to insertion and extraction of Li ions in the gap formed by the composite carbon particles (B). The presence of A) makes it possible to obtain a high-capacity negative electrode material in which the performance degradation due to the loss of contact with the composite carbon particles (B) is small.

<Physical properties>
<Average particle diameter (d50)>
The negative electrode material of the present invention preferably has an average particle size (particle size of 50% integrated part 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 diameter (d50) of the negative electrode material of the present invention is 3 μm or more, an increase in irreversible capacity due to an increase in specific surface area can be prevented. On the other hand, when d50 is 30 μm or less, it is possible to prevent the rapid charge / discharge performance from being lowered due to the decrease in the contact area between the electrolyte and the negative electrode material particles. 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 to 1.8 g / cm ³ , more preferably 0.9 to 1.7 g / cm ³ , and still more preferably 1.0 to 1.6 g · cm ^3. It is. When the tap density is within the above range, the electrolyte and the silicon oxide particles (A) can be present in the gaps formed by the composite carbon particles (B) when the negative electrode is formed. Characterization can be realized.
The tap density is measured by the method described in the example section below.

(Specific surface area)
The specific surface area by the BET method of the negative electrode material of the present invention 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, particularly preferably. Is 5 m ² / g or more. Moreover, it is 30 m < ² > / g or less normally, Preferably it is 20 m < ² > / g or less, More preferably, it is 10 m < ² > / g or less, More preferably, it is 8 m < ² > / g or less, Most preferably, it is 6.5 m < ² > / g or less. When the specific surface area is below this range, there are few sites where Li enters and exits, and the high-speed charge / discharge characteristic output characteristics and low-temperature input / output characteristics of the lithium ion secondary battery are inferior. On the other hand, when the specific surface area exceeds this range, the active material The activity with respect to the electrolytic solution becomes excessive, and an increase in the side reaction 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 Examples section below.

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

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

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

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

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

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

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

After the slurry of the negative electrode material and the binder resin is applied to the current collector and dried, the density of the active material layer formed on the current collector is increased by pressing to increase the battery per unit volume of the negative electrode active material layer. It is preferable to increase the capacity. Density of the active material layer is preferably in the range of 1.2~1.8g / cm ^3, more preferably 1.3~1.6g / cm ^3.

By setting the density of the active material layer to 1.2 g / cm ³ or more, it is possible to prevent a decrease in battery capacity accompanying an increase in electrode thickness. In addition, by setting the density of the active material layer to 1.8 g / cm ³ or less, the amount of electrolyte solution held in the voids decreases as the interparticle voids in the electrode decrease, and the mobility of alkali ions such as lithium ions decreases. It becomes possible to prevent the rapid charge / discharge performance from being reduced.

  The negative electrode active material layer is preferably configured such that the silicon oxide particles (A) are present in the gaps formed by the composite carbon particles (B). Since the silicon oxide particles (A) are present in the gaps formed by the composite carbon particles (B), the capacity can be increased and the rate characteristics can be improved.

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

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

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

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

  A positive electrode can be produced by slurrying a mixture of the positive electrode material and a binder resin with an appropriate solvent, and applying and drying to a current collector. The slurry preferably contains a conductive material such as acetylene black and ketjen black. Moreover, you may contain a thickener as desired.

  As the thickener and the binder resin, those well-known in this application, for example, those exemplified as those used for the production of the negative electrode may be used. As for the compounding ratio with respect to 100 weight part of positive electrode materials, 0.5-20 weight part is preferable for a electrically conductive material, and 1-15 weight part is especially preferable. The thickener is preferably 0.2 to 10 parts by weight, particularly 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 slurried with water. When the binder resin is slurried with an organic solvent that dissolves the binder resin such as N-methylpyrrolidone, the amount is preferably 0.5 to 20 parts by weight, particularly 1 to 15 parts by weight.

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

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

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

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

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

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

[Negative electrode / positive electrode capacity ratio]
In the non-aqueous secondary battery of the present invention, the negative electrode / positive electrode capacity ratio is preferably designed to be 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 inserting and extracting Li ions, and an electrolyte.

  EXAMPLES Hereinafter, although the content of this invention is demonstrated more concretely using an Example, this invention is not limited by a following example, unless the summary is exceeded. The values of various production conditions and evaluation results in the following examples have meanings as preferred values of the upper limit or lower limit in the embodiments of the present invention, and the preferred ranges are the upper limit or lower limit values described above, and It may be a range defined by a combination of values of the examples or values between the examples.

[Measurement and evaluation methods for physical properties and characteristics]
[Measurement of Physical Properties of Silicon Oxide Particles (A), Composite Carbon Particles (B), and Negative Electrode Material]
<Particle size distribution>
The volume-based particle size distribution is obtained by dispersing a sample in a 0.2 wt% aqueous solution (about 10 mL) of polyoxyethylene (20) sorbitan monolaurate, which is a surfactant, and using a laser diffraction / scattering particle size distribution analyzer LA- 700 (manufactured by Horiba, Ltd.) was used for measurement.

<Tap density>
It measured using the powder density measuring device tap denser KYT-3000 (made by Seishin Enterprise Co., Ltd.). After dropping the sample into a 20 cc tap cell and filling the cell fully, tap with a stroke length of 10 mm was performed 1000 times, and the density at that time was defined as the tap density.

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

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

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

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 = 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]
<Production 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 form 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.

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

<Production of non-aqueous secondary battery (coin-type battery)>
The negative electrode for evaluation produced by the above method and a lithium metal foil punched into a disk shape having a diameter of 15 mm were used as the counter electrode. Between both electrodes, an electrolytic solution in which LiPF ₆ was dissolved to 1 mol / L was impregnated in a mixed solvent of ethylene carbonate, ethyl methyl carbonate, and fluoroethylene carbonate (volume ratio = 3: 6: 1). A separator (made of a porous polyethylene film) was placed to produce a coin-type battery for performance evaluation.

<Charge capacity, discharge capacity, efficiency>
Using the non-aqueous secondary battery (coin-type battery) produced by the method described above, the charge capacity (mAh / g) and discharge capacity (mAh / g) during battery charge / discharge were measured by the following measurement method.
Charge to 5 mV with respect to the lithium counter electrode at a current density of 0.05 C, and further charge to a current density of 0.005 C at a constant voltage of 5 mV. After doping lithium into the negative electrode, the current density of 0.1 C Then, the lithium counter electrode was discharged to 1.5V.
The charge capacity and discharge capacity were determined as follows. The weight of the negative electrode active material is determined by subtracting the weight of the copper foil punched out in the same area as the negative electrode from the negative electrode weight and multiplying by the coefficient determined from the composition ratio of the negative electrode active material and the binder. The charge capacity and discharge capacity per weight were determined by dividing the charge capacity and discharge capacity of the eyes.
The charge capacity (mAh / g) at this time was defined as the 1st charge capacity (mAh / g) of the present negative electrode material, and the discharge capacity (mAh / g) was defined as the 1st discharge capacity (mAh / g).
Further, the first cycle discharge capacity (mAh / g) obtained here was divided by the charge capacity (mAh / g), and a value multiplied by 100 was defined as the 1st efficiency (%).

[Composite carbon particles (B)]
<Composite carbon particles (B1)>
The scaly natural graphite having a d50 of 100 μm was spheroidized by a 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 processed by classification to obtain spherical graphite particles having a d50 of 16.3 μm. Mixing the obtained spheroidized graphite particles and petroleum heavy oil obtained at the time of naphtha pyrolysis as a carbonaceous material precursor, subjecting it to heat treatment at 1300 ° C. in an inert gas, and then grinding and classifying the fired product Thus, composite carbon particles (B1) in which amorphous carbon was attached to the surface of the graphite particles were obtained.

  From the firing yield, in the obtained composite carbon particles (B1), the weight ratio of the spheroidized graphite particles to the amorphous carbon ([weight of spheroidized graphite particles]: [weight of amorphous carbon]) is 1. : 0.04 was confirmed. D50, d90, d10, tap density, specific surface area, circularity, and Raman R value were measured by the above measurement methods. The results are shown in Table-1.

<Composite carbon particles (B2)>
The scaly natural graphite having a d50 of 100 μm was spheroidized by a 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 processed by classification to obtain spherical graphite particles having a d50 of 10.6 μm. Mixing the obtained spheroidized graphite particles and petroleum heavy oil obtained at the time of naphtha pyrolysis as a carbonaceous material precursor, subjecting it to heat treatment at 1300 ° C. in an inert gas, and then grinding and classifying the fired product Thus, composite carbon particles (B2) in which amorphous carbon was attached to the surface of the graphite particles were obtained.

  From the firing yield, in the obtained composite carbon particles (B2), the weight ratio of the spheroidized graphite particles to the amorphous carbon ([weight of spheroidized graphite particles]: [weight of amorphous carbon]) is 1. : 0.07 was confirmed. D50, d90, d10, tap density, specific surface area, circularity, and Raman R value were measured by the above measurement methods. The results are shown in Table-1.

<Composite carbon particles (b1)>
The scaly natural graphite having a d50 of 100 μm was spheroidized by a 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 processed by classification to obtain spherical graphite particles having a d50 of 9.8 μm. Mixing the obtained spheroidized graphite particles and petroleum heavy oil obtained at the time of naphtha pyrolysis as a carbonaceous material precursor, subjecting it to heat treatment at 1300 ° C. in an inert gas, and then grinding and classifying the fired product Thus, composite carbon particles (b1) in which amorphous carbon was attached to the surface of the graphite particles were obtained.

  From the firing yield, in the obtained composite carbon particles (b1), the weight ratio of the spheroidized graphite particles to the amorphous carbon ([weight of spheroidized graphite particles]: [weight of amorphous carbon]) is 1. : 0.08 was confirmed. D50, d90, d10, tap density, specific surface area, circularity, and Raman R value were measured by the above measurement methods. The results are shown in Table-1.

<Silicon oxide particles (A1)>
Commercially available silicon oxide particles (SiOx, x = 1) (manufactured by Osaka Titanium Technologies) were heat-treated at 1000 ° C. for 6 hours under an inert atmosphere to obtain silicon oxide particles (A1). The silicon oxide particles (A1) had a d50 of 5.4 μm and a BET 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 diffraction lines attributed to Si (111) near 2θ = 28.4 °, and the silicon oxide particles (A1) have zero valence. It was confirmed that the silicon atom was contained as a microcrystal. The particle diameter of the silicon crystal determined by the Scherrer equation based on the broadening of the diffraction lines was 3.2 nm.

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

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

[Example 2]
10 parts by weight of silicon oxide particles (A1) were dry mixed with 90 parts by weight of composite carbonaceous particles (B2) to obtain a mixture. Evaluation similar to Example 1 was performed.

[Comparative Example 1]
10 parts by weight of silicon oxide particles (A1) were dry mixed with 90 parts by weight of graphite particles (b1) to obtain a mixture. Evaluation similar to Example 1 was performed.

  Table 3 summarizes d50, d90, d10, and the specific surface area of the mixtures obtained in Examples 1 and 2 and Comparative Example 1.

Moreover, the evaluation result of the battery produced using the negative electrode material which consists of a mixture obtained in Example 1, 2 and the comparative example 1 is put together in Table-4, and is shown.
Table 4 shows that the non-aqueous secondary battery using the negative electrode material of the present invention has a high capacity and excellent initial efficiency.

Claims (9)

  It contains silicon oxide particles (A) and composite carbon particles (B), the silicon oxide particles (A) contain zero-valent silicon atoms, and the composite carbon particles (B) are formed on the surface of the spheroidized graphite particles. A carbon material for a non-aqueous secondary battery negative electrode having a carbon layer at least in part and having a circularity of 0.89 or more determined by flow-type particle image analysis.   The negative electrode material for nonaqueous secondary batteries according to claim 1, wherein silicon oxide particles (A) contain silicon microcrystals. The ratio (M _O / M _Si ) of the number of oxygen atoms (M _O ) to the number of silicon atoms (M _Si ) in the silicon oxide particles (A) is 0.5 to 1.6. A negative electrode material for non-aqueous secondary batteries.   The negative electrode material for nonaqueous secondary batteries according to any one of claims 1 to 3, wherein the composite carbonaceous particles (B) include graphite obtained by spheroidizing flaky, scaly, and massive natural graphite.   The negative electrode material for nonaqueous secondary batteries according to any one of claims 1 to 4, wherein the silicon oxide particles (A) have an average particle diameter (d50) of 0.01 µm or more and 20 µm or less.   The nonaqueous secondary battery according to any one of claims 1 to 5, wherein a particle diameter (d10) of a 10% integration part from the small particle side of the silicon oxide particles (A) is 0.001 µm to 6 µm. Negative electrode material.   Average particle diameter ratio between silicon oxide particles (A) and composite carbonaceous particles (B) (R = [average particle diameter of silicon oxide particles (A) (d50)] / [average particles of composite carbonaceous particles (B) The diameter (d50)]) is 0.001 or more and 10 or less, The negative electrode material for non-aqueous secondary batteries of any one of Claims 1 thru | or 6.   A non-aqueous secondary battery negative electrode comprising a current collector and an active material layer formed on the current collector, wherein the active material layer is a non-electrode according to any one of claims 1 to 7. A negative electrode for a non-aqueous secondary battery, comprising a negative electrode material for an aqueous secondary battery.   A nonaqueous secondary battery comprising a positive electrode, a negative electrode, and an electrolyte, wherein the negative electrode is the negative electrode for a nonaqueous secondary battery according to claim 8.