JP2002356314A - Partially nitrided silicon oxynitride powder and its producing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a partially nitrided silicon oxynitride powder without cycle deterioration and capable of increasing a charge or discharge capacity of a battery when it is used for a lithium ion secondary battery or the like as an anode active substance. SOLUTION: The partially nitrided silicon oxynitride powder is obtained by heating and partially nitriding a silicon oxide powder of SiOz (0<z<2) in a nitrogen containing atmosphere, and its general formula is denoted as SiNxOy. The ranges of (x) and (y) are 0<x<1.3 and 0<y<1.5 respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a partial silicon nitride oxide powder effective as a negative electrode active material for a secondary battery such as a lithium ion secondary battery and a method for producing the same.

[0002]

2. Description of the Related Art In recent years, with the remarkable development of portable electronic devices, communication devices, and the like, a secondary battery having a high energy density has been strongly demanded from the viewpoints of economy and reduction in size and weight of the devices.

Conventionally, as a measure for increasing the capacity of this type of secondary battery, for example, oxides such as V, Si, B, Zr, and Sn,
And methods of using these composite oxides as negative electrode materials (JP-A-5-174818, JP-A-6-6086)
No. 7, JP-A-10-294112), a method using a molten and quenched metal oxide as a negative electrode material (JP-A-10-294112), and a method using silicon oxide as a negative electrode material (Japanese Patent No. 299774).
No. 1), Si ₂ N ₂ O and Ge ₂ N ₂
O (Japanese Unexamined Patent Publication No. 11-102705) and the like.

[0004]

However, in each of the above-mentioned conventional methods, although the charge / discharge capacity is increased and the energy density is improved, it is often not always satisfactory, and the cyclability is insufficient. At present, a secondary battery that sufficiently satisfies the characteristics required in the market has not been obtained, and further improvement in energy density and the like has been desired.

The present invention has been made in view of such circumstances, and aims to improve the charge / discharge capacity of a battery when used as a negative electrode active material of a secondary battery such as a lithium ion secondary battery. It is an object of the present invention to provide a partial silicon nitride oxide powder which does not cause cycle deterioration and a method for producing the same.

[0006]

Means for Solving the Problems and Embodiments of the Invention
The present inventors have conducted intensive studies in order to achieve the above object, and as a result, in particular, have found that silicon oxide powder SiO _z (where 0 <z
<2) is heated in a nitrogen gas-containing atmosphere and partially nitrided to obtain a partially nitrided silicon oxide powder represented by the general formula SiN _x O _y , which is used in a lithium ion secondary battery or the like. When used as a negative electrode material, it was found that cycle deterioration could be prevented while maintaining high capacity, and silicon oxide powder SiO _z (0 <z <2) was partially removed under a nitrogen gas-containing atmosphere at a predetermined temperature. It has been found that by partially nitriding, a partially silicon nitride oxide powder suitable as the negative electrode material can be efficiently produced, and the present invention has been completed.

That is, the present invention provides [1] a method in which silicon oxide powder SiO _z (where 0 <z <2) is partially nitrided by heating in a nitrogen gas-containing atmosphere.
It is represented by the general formula SiN _x O _y , and the range of x and y is 0 <x <
1.3, 0 <y <1.5, partial silicon nitride oxide powder, [2] the heating temperature is 1,000 to
A partial silicon nitride oxide powder according to [1], wherein the powder has a BET specific surface area of 0.5 to 50 m
Characterized in that it is a ² / g [1] or [2] moiety silicon nitride oxide powder, [4], characterized in that it is used for the negative electrode active material for a secondary battery [1] to [3] Either partial silicon nitride oxide powder or [5] silicon oxide powder SiO _z (where 0 <z <2) was
A method for producing a partially nitrided silicon oxide powder, wherein the powder is heated in a temperature range of 0 to 1,600 ° C. and partially nitrided; [6] the range of z in the SiO _z powder is 1.0
≦ z <1.6, and the BET specific surface area is 1 to 100 m ^2.
/ G, the method for producing a partially silicon oxynitride powder according to [5].

Hereinafter, the present invention will be described in more detail.

The partial silicon nitride oxide powder according to the present invention is, as described above, a silicon oxide powder SiO _z (where 0 <z <
2) is obtained by heating in an atmosphere containing nitrogen gas to partially nitride the compound, and has the general formula SiN _x
Is represented by O _y, x, the range of y is, 0 <x <1.3,0 <
y <1.5.

Here, when the above-mentioned x value is 0, it means that partial nitriding, which is a feature of the present invention, has not been performed, and even if the powder is used as a negative electrode active material for a secondary battery or the like, a high capacity and Thus, a secondary battery without cycle deterioration cannot be obtained. On the other hand, when the x value is 1.3 or more, it becomes difficult to perform doping and undoping of lithium.

When the y value is 0, the cyclability of the obtained secondary battery is reduced. On the other hand, when the y value is 1.5 or more, a high capacity secondary battery cannot be obtained. It will be. In consideration of further improving the battery characteristics of the secondary battery using the partial silicon nitride oxide powder as the negative electrode active material, the range of x and y is 0.5 ≦ x ≦
Preferably, 1.0, 0.3 ≦ y ≦ 1.0.

Although the physical properties of the partially nitrided silicon oxide powder of the present invention are not particularly limited, the powder has a BET specific surface area of 0.5 to 50 m ² / g, particularly 1 to 30 m ² / g. Is preferred.

Here, the BET specific surface area is 0.5 m ² / g.
If it is less than 3, the surface activity of the powder becomes small, and it may be difficult to obtain a high capacity lithium ion secondary battery or the like. On the other hand, when the BET specific surface area exceeds 50 m ² / g,
There is a possibility that the handling property at the time of manufacturing the electrode is deteriorated. Here, the BET specific surface area is a value measured by a BET one-point method by nitrogen gas adsorption.

Next, a method for producing a partially silicon nitride oxide powder according to the present invention will be described.

As described above, the method for producing a partially nitrided silicon oxide powder according to the present invention uses a silicon oxide powder SiO _z (where 0 <z <) as a raw material powder for generating SiO gas.
Using 2), the powder was placed in an atmosphere containing
It is characterized in that it is heated in a temperature range of 00 to 1,600 ° C. and partially nitrided.

Here, the specific silicon oxide powder S used in the present invention is used as a raw material powder for generating SiO gas.
When a mixture of silicon dioxide and a powder for reducing the same (eg, a metal silicon compound, a carbon-containing powder, etc.) is used in addition to iO _z , x and y of the partially silicon nitride oxide powder (SiN _x O _y ) are used. Not only is it difficult to control the value, but also a negative electrode active material for a secondary battery such as a lithium ion secondary battery having a high capacity and excellent cycle deterioration prevention properties cannot be obtained. .

In this case, the physical properties of the SiO _z powder are not particularly limited, but the range of z is 1.0 ≦ z <1.
6, particularly 1.0 ≦ z ≦ 1.3, and the BET specific surface area is preferably ¹ to 100 m ² / g, particularly preferably ^{3 to} 50 m ² / g.

While it is difficult to produce SiO _z powder having the above z value smaller than 1.0, when the z value is 1.6 or more, S
Since the activity of iO _z powder is lowered, there is a case where x parts silicon nitride oxide powder (SiN _x O _y), is possible to control the y value to the predetermined value described above it becomes difficult.

Also, when the BET specific surface area is less than 1 m ² / g, the activity of the SiO _z powder is reduced.
In some cases, it may be difficult to obtain a partially nitrided silicon oxide powder having a y-value. On the other hand, if it exceeds 100 m ² / g, the inactive SiO _z component increases, and the partial nitridation reaction may not easily proceed. There is.

The BET specific surface area is a value measured by the same method as in the case of the above partial silicon nitride oxide powder.

The above "under a nitrogen gas-containing atmosphere" includes:
There is no particular limitation as long as it is under a non-oxidizing atmosphere containing nitrogen gas.In addition to the atmosphere under nitrogen gas alone, for example, under an atmosphere containing nitrogen gas reduced in pressure for the purpose of controlling reactivity, or under nitrogen Ar, nitrogen gas for the purpose of adjusting the partial pressure
For example, under a nitrogen gas-containing atmosphere in which a non-oxidizing gas such as H ₂ or He is mixed.

The temperature range in which the raw material powder is partially nitrided in an atmosphere containing nitrogen gas is 1,000 to 1,600.
In consideration of making the partial nitriding reaction proceed more efficiently, the range of 1,100 to 1,500 ° C. is more preferable. When the reaction temperature is lower than 1,000 ° C., will be partially nitriding reaction does not proceed, while when it exceeds 1,600 ° C., since the reactivity too high, an inactive Si ₃ N ₄ powder as a negative electrode material It becomes a main product.

As described above, in the production method of the present invention, the partial silicon nitride oxide powder (SiN _x O _y ) is obtained by appropriately adjusting the physical properties (z value), the nitrogen partial pressure, and the reaction temperature of SiO _z used as a raw material. ) Can be controlled within a predetermined range.

As a specific method for producing the above partial silicon nitride oxide powder, for example, the following method can be mentioned.

First, SiO _z (0 <z <2, particularly 1.0
≦ z ≦ 1.6) After the powder is charged into a silicon nitride tray, it is charged into a reaction furnace (for example, an effective volume of 10 to 15 L (liter)), and N ₂ gas is supplied at 1 to 30 NL / min, particularly 3 While flowing at ~ 15NL / min, 1,000 ~
Heat to 1600 ° C. for 0.5-10 hours, especially 2-8
Partial nitriding is performed for a time (for example, at 1,200 ° C., 3 to 10 hours, particularly about 5 to 8 hours, and at 1,400 ° C., 1 to 10 hours, particularly about 2 to 5 hours). By pulverizing and pulverizing the thus obtained partial silicon nitride oxide, a partial silicon nitride oxide powder can be manufactured.

The production method is not particularly limited, and the reaction can be carried out by a continuous method or a batch method. Specifically, a fluidized bed reactor, a rotary furnace, a vertical moving bed reactor, a tunnel furnace, a batch furnace, A furnace or the like can be appropriately selected and used depending on the purpose or the like.

When the partially silicon nitride oxide powder of the present invention described above is used as a negative electrode active material for a lithium ion secondary battery or the like, the charge and discharge capacity of the secondary battery can be increased, and the cycle deterioration Can be prevented.

Here, since the above partially silicon nitride oxide powder is an insulator, when it is used as a negative electrode material for a secondary battery, it is necessary to add a conductive material.

In this case, the conductive material that can be used is not particularly limited as long as it is an electronic conductive material that does not cause decomposition or deterioration in the constructed battery or the like.
Metal powder or metal fiber such as i, Fe, Ni, Cu, Zn, Ag, Sn, Si, etc., natural graphite, artificial graphite, various coke powders, mesophase carbon, vapor-grown carbon fiber, pitch-based carbon fiber, PAN-based Carbon fibers, various types of resin fired bodies, and the like can be used.

The above secondary battery is characterized in that the partially silicon nitride oxide powder of the present invention is used as the negative electrode active material of the secondary battery. Therefore, the other secondary battery components, that is, the positive electrode, the negative electrode, and the electrolyte are used. The material of the separator, the shape of the battery, etc. can be arbitrarily selected.

As the positive electrode active material constituting the positive electrode, for example, LiCoO ₂ , LiNiO ₂ , LiMn ₂ O ₄ , V
Oxides of transition metals such as ₂ O ₅ , MnO ₂ , TiS ₂ , MoS ₂ , chalcogen compounds and the like can be used.

The electrolyte is not particularly limited. For example, a non-aqueous electrolyte containing a lithium salt such as lithium perchlorate and a non-aqueous solvent, a non-aqueous electrolyte containing another electrolyte salt and a non-aqueous solvent, a solid electrolyte Are used. As the non-aqueous solvent used for the non-aqueous electrolyte, propylene carbonate, ethylene carbonate, dimethoxyethane, γ-butyrolactone, 2-methyltetrahydrofuran, or the like can be used alone or in combination of two or more.

[0033]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples. In the following description,
wt and wt% mean weight and weight%, respectively.

[Example 1] [1] Production of partial silicon nitride oxide powder SiO _z (z = 1.05, BET specific surface area: 33.5 m ²⁾
/ G) After charging 200 g of powder into a silicon nitride tray,
Charge into a reactor (effective volume: 15L) and add 1 N ₂ gas
While flowing at 0 NL / min, partial nitriding was performed at a temperature of 1,400 ° C. for 3 hours to obtain 190 g of a gray lump intermediate of partially silicon nitrided oxide. The BET specific surface area of this gray lump intermediate was 5.7 m ² / g.

Next, 100 g of the obtained gray lump intermediate was obtained.
Was charged into a 2L alumina ball, 1,000 g of a φ5 mm alumina ball as a grinding medium and 500 g of hexane as a solvent were added to the ball, and wet grinding was performed under a rotation condition of 1 rpm.

The partially silicon nitride oxide powder obtained by pulverization has an average particle size of 5.5 μm and a BET specific surface area of 18.2 m.
² / g, nitrogen content 14.1 wt%, oxygen content 26.
5 wt%, and the general formula SiN _x O _y (x = 0.47, y
= 0.78).

Tables 1 and 2 show the reaction conditions and the physical properties of the obtained partial silicon nitride oxide powder.

[2] Preparation of Lithium Ion Secondary Battery Using the partially silicon nitride oxide powder obtained as described above as a negative electrode active material, a lithium ion secondary battery was prepared by the following method.

First, artificial graphite (average particle size: 5 μm) was blended with the above partial silicon oxynitride powder so that the ratio of carbon became 50 wt% to prepare a mixture. 10 wt% of polyvinylidene fluoride was added to the obtained mixture, and 5 wt% of N-methylpyrrolidone was further added to form a slurry.

The obtained slurry was applied to a copper foil having a thickness of 20 μm, dried at 120 ° C. for 1 hour, and then press-molded by a roller press to produce an electrode, and finally punched out to a thickness of 20 mm to obtain a negative electrode.

Next, a lithium foil was used as a counter electrode of the obtained negative electrode, and lithium phosphate hexafluoride was used as a non-aqueous electrolyte to prepare 1 / of ethylene carbonate and 1,2-dimethoxyethane.
A lithium ion secondary battery for evaluation was produced using a non-aqueous electrolyte solution dissolved at a concentration of 1 mol / L in a 1 (volume ratio) mixed solution and a polyethylene porous film having a thickness of 30 μm as a separator.

[Examples 2 to 5] [1] Production of partial silicon nitride oxide powder Partial nitridation reaction conditions (reaction temperature, N ₂ gas partial pressure, raw material Si
A partial silicon nitride oxide powder was obtained in the same manner as in Example 1 except that the z value of O _z powder) was changed as shown in Table 1.

With respect to the obtained partial silicon nitride oxide powder,
The average particle diameter, BET specific surface area, nitrogen content, oxygen content, and x, y values were measured. Table 2 shows the results.

[2] Preparation of Lithium Ion Secondary Battery A lithium ion secondary battery for evaluation was prepared in the same manner as in Example 1 using each of the above partial silicon nitride oxide powders.

Example 6 [1] Production of Partial Silicon Nitride Oxide Powder Metal silicon powder (BET specific surface area: 5.2 m ² / g)
A mixed raw material powder obtained by mixing silicon dioxide powder (BET specific surface area: 200 m ² / g) at an equimolar ratio was mixed under reduced pressure.
By heating and maintaining the temperature at 1,300 ° C., a silicon monoxide gas was generated, and the silicon monoxide gas was rapidly cooled and deposited in a water-cooled deposition tube to produce a SiO _z (z = 1) powder. Subsequently, 200 g of the obtained SiO _z (z = 1) powder was charged into a high-temperature atmosphere furnace (effective volume: 15 L), and N ₂ gas was added in an amount of 1 g.
While flowing at 0 NL / min, the mixture was heated to 1,400 ° C. and maintained for 2 hours to obtain 185 g of a partially silicon nitride oxide powder.
X, y of the obtained partial silicon nitride oxide powder (SiN _x O _y )
The values were x = 1.0, y = 0.5.

FIG. 1 shows an X-ray diffraction diagram of this partially silicon oxynitride powder. It was confirmed that the obtained partial silicon nitride oxide powder was substantially pure without other impurities.

Example 7 [1] Production of Partially Silicon Nitride Oxide Powder By the same method for producing silicon oxide powder as in Example 6, z =
1.20 silicon oxide (SiO_zA) make a powder and use this acid
Partial nitric acid was obtained using silicon nitride powder under the same conditions as in Example 6.
180 g of silicon oxide powder was produced. Obtained partial oxynitride
Silicon powder (SiN _xO_y) Is x = 1.05,
y = 0.54.

FIG. 2 shows an X-ray diffraction diagram of the partially silicon nitride oxide powder. It was confirmed that the obtained partial silicon nitride oxide powder was substantially pure without other impurities.

Example 8 [1] Production of Partial Silicon Nitride Oxide Powder 190 g of partially silicon nitride oxide powder was obtained in the same manner as in Example 6 except that the nitriding reaction temperature was 1,550 ° C. The x, y values of the obtained partially silicon nitride oxide powder (SiN _x O _y ) were x = 1.18, y = 0.38.

FIG. 3 shows an X-ray diffraction chart of the partially silicon nitride oxide powder. Since the reaction temperature is somewhat higher, a small amount of silicon nitride is found in the obtained partially nitrided silicon oxide powder.

[Example 9] [1] Production of partially silicon nitrided oxide powder
0.87 silicon oxide (SiO_zA) make a powder and use this acid
Partial nitric acid was obtained using silicon nitride powder under the same conditions as in Example 6.
185 g of silicon oxide powder was produced. Obtained partial oxynitride
Silicon powder (SiN _xO_y) Is x = 0.92,
y = 0.71.

FIG. 4 shows an X-ray diffraction diagram of this partially silicon oxynitride powder. The z value of the silicon oxide (SiO _z ) powder is 0.8
7, which is relatively low, it can be seen that silicon nitride is mixed in the obtained partial silicon nitride oxide powder.

Example 10 [1] Production of Partial Silicon Nitride Oxide Powder A method for producing silicon oxide powder similar to that of Example 6
1.4 silicon oxide (SiO _z ) powder was produced, and 190 g of a partially nitrided silicon oxide powder was produced using this silicon oxide powder under the same conditions as in Example 6. The x and y values of the obtained partially nitrided silicon oxide powder (SiN _x O _y ) are x = 0.88, y
= 0.93.

FIG. 5 shows an X-ray diffraction pattern of the partially silicon nitride oxide powder. The z-value of silicon oxide (SiO _z ) powder is 1.4
It is understood that cristobalite (SiO ₂ ) was mixed in the obtained partially silicon nitride oxide powder.

[Comparative Examples 1 to 3] [1] Production of (partially nitrided) silicon oxide powder Partial nitridation reaction conditions (reaction temperature, N ₂ gas partial pressure, raw material Si
A (partially nitrided) silicon oxide powder was obtained in the same manner as in Example 1 except that the z value of O _z powder) was changed as shown in Table 1.

The obtained (partially nitrided) silicon oxide powder was measured for average particle diameter, BET specific surface area, nitrogen content, oxygen content, and x, y values. Table 2 shows the results.

[2] Production of Lithium-Ion Secondary Battery A lithium-ion secondary battery for evaluation was produced in the same manner as in Example 1 using each of the above partial silicon nitride oxide powders.

[0058]

[Table 1]

[0059]

[Table 2]

The lithium ion secondary batteries for evaluation produced in Examples 1 to 5 and Comparative Examples 1 to 3 were subjected to the following charge / discharge tests.

[Charge / Discharge Test] Each of the prepared lithium ion secondary batteries for evaluation was left overnight at room temperature, and then the voltage of the test cell was measured using a secondary battery charge / discharge tester (manufactured by Nagano Corporation). The battery was charged at a constant current of 1 mA until the voltage reached 0 V, and after the voltage reached 0 V, the current was reduced to keep the cell voltage at 0 V, and the battery was charged. And the current value is 20 μA
The charging was terminated when the value fell below the threshold.

Thereafter, discharging was performed at a constant current of 1 mA. When the cell voltage exceeded 1.8 V, the discharging was terminated, and the discharge capacity was measured.

Subsequently, the above charge / discharge test was repeated, and a charge / discharge test after 10 cycles was performed for each lithium ion secondary battery for evaluation, and a discharge capacity after 10 cycles and a capacity retention rate after 10 cycles were measured. . Table 3 shows the obtained results.

[0064]

[Table 3]

As shown in Table 3, the lithium ion secondary batteries using the partial silicon nitride oxide powders of Examples 1 to 5 as the negative electrode active material had an initial discharge capacity of 980 to 1150 m.
It is understood that the secondary battery has a high capacity of Ah / g and a high capacity retention rate after 10 cycles of 80 to 89.8%, that is, a high capacity and excellent cycleability.

On the other hand, Comparative Examples 1 to 3 do not satisfy the x and y values of the partially silicon oxynitride powder (SiN _x O _y ) of the present invention, and thus satisfy both the capacity and the cycleability. It can be seen that a secondary battery has not been obtained.

That is, in Comparative Example 1, although the initial discharge capacity was high, the cycle retention rate was lower than in each of the examples. In Comparative Examples 2 and 3, the cycle retention rate was excellent, but the discharge capacity was extremely low. I have.

Comparative Example 4 Fumed silica (Si
Mixed powder 2 in which O ₂ , BET specific surface area: 200 m ² / g) and reagent grade metallic silicon (Si, BET specific surface area: 3.5 m ² / g) were mixed at a molar ratio of SiO ₂ / Si = 1/3.
00 g was charged into the reactor, and N ₂ gas was supplied at 10 NL / mi.
While flowing in with n, a nitriding reaction was carried out at a temperature of 1,450 ° C. for 3 hours to obtain a partially silicon nitrided oxide powder.

The obtained partially silicon nitride oxide powder has an average particle diameter of 6.2 μm, a BET specific surface area of 15.3 m ² / g, and a nitrogen content of 28 wt%. General formula S with an oxygen content of 14 wt%
It was a partially silicon nitride oxide powder of iN _x O _y (x = 1.0, y = 0.5).

Using this powder, a lithium ion secondary battery for evaluation was produced in the same manner as in Example 1 above, and the battery was evaluated. The initial discharge capacity was 210 mAh / g, and the initial discharge capacity was 210 mAh / g.
Discharge capacity after cycling 200 mAh / g, capacity retention 9
It was 5.2%, which was almost an inert substance almost equivalent to the volume of only graphite added.

[0071]

As described above, the partially nitrided silicon oxide powder of the present invention is represented by the general formula SiN _x O _y , and the range of x, y is 0 <x <1.3, 0 <y. Since it satisfies <1.5, when used as a negative electrode active material for a secondary battery such as a lithium ion secondary battery, a secondary battery having high capacity and excellent cycle characteristics can be obtained.

[Brief description of the drawings]

FIG. 1 shows the X of the partially silicon oxynitride powder obtained in Example 6.
FIG.

FIG. 2 shows the X of the partially silicon oxynitride powder obtained in Example 7.
FIG.

FIG. 3 shows the X of the partially silicon oxynitride powder obtained in Example 8.
FIG.

FIG. 4 shows the X of the partially silicon oxynitride powder obtained in Example 9.
FIG.

FIG. 5 is an X-ray diffraction diagram of the partially silicon oxynitride powder obtained in Example 10.

Continuing from the front page (72) Inventor Kenji Ooka 2-13-1, Isobe, Annaka-shi, Gunma Inside the Isobe Service Co., Ltd. (72) Inventor Mikio Arata 2- 13-1, Isobe, Annaka-shi, Gunma Shin-Etsu (72) Inventor Susumu Ueno 2-13-1, Isobe, Annaka-shi, Gunma Shin-Etsu Chemical Co., Ltd. Gunma Office (72) Inventor Kazuma Kuii Isobe, Annaka-shi, Gunma No. 13-1, Shin-Etsu Kagaku Kogyo Co., Ltd. Gunma Office (72) Inventor Ken Fukuda 2-6-1 Otemachi, Chiyoda-ku, Tokyo Shin-Etsu Chemical Co., Ltd. F term (reference) 4G072 AA38 BB05 GG01 GG03 HH14 JJ50 RR07 TT06 UU30 5H029 AJ03 AJ05 AK02 AK03 AK05 AL01 AM03 AM04 AM05 AM07 AM16 CJ02 CJ11 CJ28 DJ16 DJ17 EJ03 EJ09 HJ02 HJ07 HJ14 5H050 AA07 AA08 BA15 CA02 CA08 CA09 CA10 CA11 GA02

Claims (6)

[Claims] A silicon oxide powder SiO _z (where 0 <z <
2) is represented by a general formula SiN _x O _y obtained by heating and partially nitriding in an atmosphere containing nitrogen gas, and the range of x and y is 0 <x <1.3, 0 < y <1.5
A partially silicon nitrided oxide powder, characterized in that: 2. The heating temperature is 1,000 to 1,600.
2. The partially silicon nitride oxide powder according to claim 1, wherein the temperature is ° C. 3. 3. A BET specific surface area of 0.5 to 50 m ² / g.
The partially silicon nitride oxide powder according to claim 1 or 2, wherein: 4. The partially silicon nitride oxide powder according to claim 1, which is used for a negative electrode active material of a secondary battery. 5. Silicon oxide powder SiO _z (where 0 <z <
2) in a nitrogen gas-containing atmosphere at 1,000 to 1,60
A method for producing a partially nitrided silicon oxide powder, wherein the powder is heated in a temperature range of 0 ° C. and partially nitrided. 6. The SiO _z powder has a z range of 1.0 ≦ z <1.6 and a BET specific surface area of 1 to 10
The process according to claim 5 parts silicon nitride oxide powder, wherein the a 0 m ² / g.