JPH10273320A - Production of tin oxide powder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain spherical tin oxide powder useful for a negative electrode activator of a nonaqueous electrolyte secondary battery, large in charge capacity and service capacity and high in packing density, by dispersing tin and a compound to provide a raw material for a secondary component element in a solution state, gelatinizing and successively baking. SOLUTION: An organic solvent-soluble tin compound and/or metal tin and at least one soluble compound selected from the group consisting of an alkaline earth metal, a rare earth element compound, a transition element compound, an element compound of the group 13 of the periodic table, an element compound of the group 14 of the periodic table (except tin compound), an element compound of the group 15 of the periodic table and a chalcogen element compound each soluble in an organic solvent are dissolved in an organic solvent. The solution is mixed with a suspending solvent incompatible with the organic solvent to give a suspension in which the organic solvent having dissolved the soluble compound is dispersed into the suspending solvent or the suspending solvent having dissolved the soluble compound is dispersed into the organic solvent. Then the suspension is made into a spherical get and the spherical gel is baked to give the objective tin oxide powder.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a spherical tin oxide powder and a nonaqueous electrolyte secondary battery using the tin oxide powder as a negative electrode active material.

[0002]

2. Description of the Related Art As a power source for portable devices such as mobile phones, portable terminals, and video cameras, which are rapidly spreading today, or as a power source for electric vehicles, there is a social demand for a small, lightweight, and high energy density secondary battery. The demands are getting stronger.

[0003] Among secondary batteries that can be charged and used repeatedly, secondary batteries such as lead-acid batteries, nickel-cadmium batteries, and nickel-hydrogen batteries that use aqueous electrolytes, except for lead-acid batteries with high overvoltages, use water. A high battery voltage exceeding the decomposition voltage cannot be obtained. On the other hand, since the nonaqueous electrolyte secondary battery uses a nonaqueous solvent for the electrolyte, a higher battery voltage can be obtained than the above-described secondary battery using an aqueous electrolyte. Non-aqueous electrolyte secondary batteries have a high energy density and can be made smaller and lighter, and their demand for power supplies for portable devices is growing rapidly. Further, there is a demand for further improvement in battery capacity.

[0004] Non-aqueous electrolyte secondary batteries occlude lithium,
A positive electrode composed of a positive electrode active material capable of releasing and a current collector, a negative electrode composed of a negative electrode active material capable of inserting and extracting lithium and a current collector, and a lithium salt in a non-aqueous solvent It is composed of a dissolved electrolyte, a separator, a battery container and the like. In such a secondary battery, lithium released from the positive electrode active material during charging is occluded in the negative electrode active material, and lithium discharged from the negative electrode active material on the contrary during discharging is occluded in the positive electrode active material. You. Therefore, in order to improve the battery capacity, to improve the charge and discharge capacity of the negative electrode or the positive electrode active material itself,
It is important to increase the packing density of the active material in the negative electrode or the positive electrode.

As a negative electrode active material suitable for a non-aqueous electrolyte secondary battery having a high charge / discharge capacity, it is desirable to use metallic lithium containing the largest amount of lithium per unit weight, focusing only on the energy density. . However, when lithium metal is used as the negative electrode active material, lithium is not uniformly deposited on the surface of the negative electrode during charging but is deposited in a dendritic manner, which penetrates through the separator and short-circuits the negative electrode and the positive electrode. There is. In addition, there is a problem in that metallic lithium precipitated in a dendritic form falls off the negative electrode and the charge / discharge cycle life is shortened. Due to these problems, metallic lithium has not been put to practical use as a negative electrode active material, though it has the highest theoretical lithium capacity involved in the battery reaction.

At present, as a negative electrode active material of a commercially available non-aqueous electrolyte secondary battery, a carbon material having a relatively high crystallinity represented by graphite (hereinafter, also referred to as a graphite material), a non-graphitizable carbon, etc. Carbon materials having a relatively low crystallinity (hereinafter also referred to as non-graphitizable carbon materials) are used.

When a graphite material is used as a negative electrode active material of a non-aqueous electrolyte secondary battery (hereinafter also referred to as a negative electrode active material), the negative electrode potential is stabilized at a substantially constant value from the beginning to the end of the discharge. A stable battery voltage can be secured until the end. However, the charge / discharge capacity of the graphite material is up to 372 mAh / g in theoretical value, and actually 280 to 33
It is about 0 mAh / g. Therefore, in order to produce a nonaqueous electrolyte secondary battery having a higher energy density, a negative electrode active material having a higher charge / discharge capacity is desired.

On the other hand, the non-graphitizable carbon material has a charge / discharge capacity of 400 to 700 mAh / g, and in this respect, has characteristics superior to those of the graphite material. However, in non-graphitizable carbon materials, since the negative electrode potential continues to rise from the beginning of discharge,
When used for a non-aqueous electrolyte secondary battery, the battery voltage keeps decreasing with discharge. Therefore, despite the fact that sufficient releasable lithium still remains in the non-graphitizable carbon, which is the negative electrode active material, further discharge occurs at a low voltage and cannot be used as a power source. There is. As a result, the charge / discharge capacity that can be substantially used may be only about 300 mAh / g, which is almost the same as that of the graphite material.

In recent years, tin oxide-based materials have attracted attention as a material having a high charge / discharge capacity. In the case of tin oxide-based materials, SnO or SnO
₂ , a high discharge capacity of 500 to 600 mAh / g was found (JP-A-6-275268, JP-A-7-122274, etc.). Then, a Sn-Li-O-based material (JP-A-7-201318), a Sn-Si-O-based material (JP-A-7-230800), or a Sn-MO-based material (M is an alkaline earth metal, Tables 13, 14, 1
A tin oxide-based material having a composition such as a group V element or zinc, and JP-A-7-288123) has been proposed. In these tin oxide-based materials, the charge / discharge cycle characteristics were somewhat improved, but the discharge capacity was lower than that of SnO or SnO ₂ .
On the contrary, it shows a tendency to decrease and it is not enough.

For example, the discharge capacity of Li _x SnO is 300
mAh / g or less (estimated from the capacity of the battery), and each of Li ₂ SnO ₃ and Li ₂ SnO ₂ produced by the solid phase reaction is 44 mA.
2,483 mAh / g, and about 493 mAh / g in the case of amorphous SnSiO ₃ produced by the melting method, all of these discharge capacities are equal to or less than SnO or SnO _2. A further increase in capacity is required. That is, the increase in the charge / discharge capacity has been saturated, and it has been demanded to improve the capacity from a new viewpoint.

On the other hand, increasing the packing density of the negative electrode active material in the negative electrode can increase the energy density per unit volume of the nonaqueous electrolyte secondary battery, and is therefore important in improving the battery capacity. is there.

In order to increase the filling density of the tin oxide-based material in the negative electrode, it is most preferable that the tin oxide-based material is a spherical powder. In addition, when the tin oxide powder is tin oxide containing no second component element, the cycle characteristics may not be sufficient, and by including the second component element, the specific surface area, the pore diameter, etc. of the tin oxide powder may be reduced. May be controlled to improve the charge / discharge capacity in some cases. Therefore, in order to improve the battery capacity of a non-aqueous electrolyte secondary battery, tin oxide having a spherical shape and optimized battery characteristics such as cycle characteristics and charge / discharge capacity by adding a second component element is used. Powder is most desirable.

However, in the conventionally known method for producing spherical tin oxide powder, the type and content of the second component element that can be contained are limited. For this reason,
Heretofore, it has not been possible to optimize the battery characteristics by adding the second component element and produce a tin oxide powder having a spherical shape.

A conventionally known method for preparing a spherical tin oxide powder is to prepare tetra-n-butoxytin (Sn (O-) in a mixed solvent of acetonitrile / n-octanol.
There is a method of precipitating n-C ₄ H ₉ ) ₄ ) in a colloidal form, hydrolyzing the spherical tetra-n-butoxytin to form a spherical gel, and calcining the gel (Inorganic Materials, Vol. 3, 5, 177-87, 1996).

However, in this reference, spherical tin oxide is secondarily used.
There is no description on the method for incorporating the component elements. In order to obtain a spherical tin oxide powder containing the second component element by using this method, it is necessary to add a compound of the second component element that is soluble in the mixed solvent. However, in this method, the solubility of tetra-n-butoxytin in the mixed solvent is controlled by the mixing ratio of acetonitrile and n-octanol to control the precipitation of tetra-n-butoxytin, so that it is contained in the mixed solvent. The compound of the second component element needs to have a solubility close to the solubility of tetra-n-butoxytin in the mixed solvent. If the solubility of the compound of the tetra-n-butoxytin and the second component element in the mixed solvent is different, not only does the composition of the obtained tin oxide powder deviate from the charged composition, but also the colloidal precipitate does not precipitate in the mixed solvent. The undissolved components may also be precipitated by hydrolysis, which may cause a problem that the components are mixed into the tin oxide powder as impurity powder having a biased composition. In addition, since it is generally extremely difficult to arbitrarily select the solubility of the compound of the second component element, the usable second component element and the amount of the second component element to be used are considerably limited by this method, and the battery characteristics are optimized. It was not possible to produce a converted spherical tin oxide powder.

In this method, droplets of tetra-n-butoxytin are precipitated in the mixed solution, and a spherical shape is obtained by the surface tension. Therefore, in order to produce a spherical tin oxide-based material powder containing the second component element, the raw material of tin and the second component element must be deposited as droplets in the mixed solution, that is, in a liquid state. is required. For this reason, there is a problem that in many cases, the raw materials of tin and the second component element must be selected from expensive alkoxide-based compounds.

As described above, the conventional method for producing spherical tin oxide is intended to produce spherical tin oxide powder suitable as a negative electrode active material of a non-aqueous electrolyte secondary battery such as a lithium ion battery, and to increase the charge / discharge capacity. Was not enough.

[0018]

Therefore, the second component element is contained in an optional amount, and the charge / discharge capacity is increased by controlling the fine structure, and the oxide having a spherical shape is formed to further increase the packing density. Development of a method for producing tin powder has been required.

[0019]

Means for Solving the Problems The present inventor has conducted intensive studies from various angles to solve the above-mentioned problems. as a result,
By dispersing the compound serving as the raw material of tin and the second component element in a solution state, gelling and then firing,
It has been found that a spherical tin oxide powder uniformly containing a wide range of types and compositions of the second component element can be obtained. Such a tin oxide has a large charge / discharge capacity and a high packing density, so that it has been found that the battery capacity can be increased. Thus, the present invention has been completed.

That is, the present invention relates to an organic solvent-soluble tin compound and / or metallic tin, an organic solvent-soluble alkaline earth metal compound, an organic solvent-soluble rare earth element compound, an organic solvent-soluble transition element compound, and an organic solvent-soluble periodic table. 13
At least one selected from the group consisting of a group 14 element compound, an organic solvent-soluble periodic table group 14 element compound (excluding an organic solvent-soluble tin compound), an organic solvent-soluble periodic table group 15 element compound, and an organic solvent-soluble chalcogen element compound. A solution in which a soluble compound is dissolved in an organic solvent is added to a suspension solvent that is incompatible with the organic solvent, and the organic solvent in which the soluble compound is dissolved is dispersed in the suspension solvent or the suspension in which the soluble compound is dissolved. A method for producing a spherical tin oxide powder, comprising forming a suspension in which a solvent is dispersed in an organic solvent, forming a spherical gel from the suspension, and then firing the spherical gel.

Another aspect of the present invention is a negative electrode active material for a non-aqueous secondary battery, comprising the tin oxide powder obtained by the above-mentioned production method.

Still another invention relates to a negative electrode obtained by bonding the above-mentioned negative electrode active material for a non-aqueous electrolyte secondary battery to a current collector, and a positive electrode active material comprising a material capable of inserting and extracting lithium ions. A non-aqueous electrolyte secondary battery characterized in that a positive electrode formed by bonding a non-aqueous electrolyte to a current collector is housed in a battery container together with a non-aqueous electrolyte through a separator.

Hereinafter, the present invention will be described specifically.

In the method for producing a spherical tin oxide powder of the present invention, first, an organic solvent-soluble tin compound and / or metallic tin, and an organic solvent-soluble alkaline earth metal compound,
Organic solvent soluble rare earth element compound, organic solvent soluble transition element compound, organic solvent soluble periodic table group 13 element compound, organic solvent soluble periodic table group 14 element compound (excluding organic solvent soluble tin compound), organic solvent soluble periodic rule Table 1
A solution in which at least one soluble compound selected from the group consisting of a group V element compound and an organic solvent-soluble chalcogen element compound (hereinafter, also referred to as an organic solvent-soluble compound) is dissolved in an organic solvent (hereinafter, also referred to as a precursor solution). Is prepared.

In the present invention, the organic solvent used for preparing the precursor solution is not particularly limited as long as the organic solvent-soluble tin compound, metal tin and organic solvent-soluble compound described below are dissolved. Examples of such an organic solvent include alcohol, acetone, acetonitrile, and the like, and a mixture thereof, and usually an alcohol is mainly used.

Specific examples of these alcohols include methanol (also called methyl alcohol), ethanol (also called ethyl alcohol), propanol (also called propyl alcohol), butanol (also called butyl alcohol), octanol (octyl alcohol), Methoxyethanol, 2-ethoxyethanol, ethylene glycol, 1-methoxy-2-propyl alcohol,
Methoxyethoxyethanol, 2-phenylethyl alcohol, benzyl alcohol, allyl alcohol, 2-
Methyl-2-propen-1-ol, 3-methyl-3-
Buten-1-ol and the like can be mentioned. Among them, methanol and ethanol are preferred because of high solubility of the organic solvent-soluble compound, and methanol is more preferred because it is inexpensive and easily available. The above-mentioned alcohol is usually used alone, but a mixture of two or more alcohols may be used to control the reactivity and solubility with the organic solvent-soluble compound.

Examples of the organic solvent-soluble tin compound (hereinafter also referred to as a tin compound) used in the present invention include tin halide, organotin, tin alkoxide and the like. The halogens in the tin halide are Cl, Br, I, and F atoms. Hydrates may also be used. Of these compounds, tin halide is more preferably used. Of the tin halides, tin chloride and tin bromide are particularly preferred from the viewpoint of price and stability.

Specifically, SnCl ₂ , SnCl ₂ .2H
₂₀ , SnBr ₂ , SnI ₂ , SnF _{2 and the} like. In particular, SnCl ₂ , SnBr ₂ , SnCl ₂ .2H ₂ O are preferably used. Further, the tin halide compound modified with an organic compound, for example, Sn (CH ₃ ) ₂ Cl ₂ can also be used. As the organic tin compound, (CH ₃ ) ₂ S
n, (C ₂ H ₅ ) ₂ Sn, (C ₃ H ₇ ) ₄ Sn or the like can be used or contained in a range where it can be dissolved. Examples of tin alkoxides include Sn (OC ₂ H ₅ ) ₄ and Sn (OC 2
₃ H ₇ ) ₄ and Sn (OC ₄ H ₉ ) ₄ .
Further, a mixture of two or more kinds of the tin compounds may be used.

The shape of the metallic tin used in the present invention is not particularly limited, and examples thereof include a plate, a bar, a sheet, a granule, a powder, a sand, a flower, and a lump. From the point of view, granules, powders and sands are preferred. The purity is preferably higher, but is not particularly limited as long as it does not affect the battery reaction and further the battery performance.

The ratio of the organic solvent to the tin compound and / or metal tin in preparing the precursor solution is not particularly limited as long as the tin compound and / or metal tin are uniformly dissolved in the organic solvent. However, if there is too little organic solvent,
The tin compound and / or metal tin are not completely dissolved, leaving insolubles, and a uniform precursor solution cannot be obtained. When the amount of the organic solvent is too large, the dissolution rate of the tin compound and / or the metal tin increases, but it takes time for the subsequent concentration. Therefore, although the ratio varies depending on the type of the organic solvent and the tin compound and / or the metal tin used, the ratio is preferably such that the amount of the organic solvent is 2 to 1000 times in molar ratio with respect to tin in terms of element. It is desirable that the ratio be 5 to 500 times. When using only metal tin as a tin source,
It is preferable to add a hydrogen halide gas such as hydrogen chloride, hydrochloric acid, or the like because the dissolution rate of metal tin in an organic solvent increases.

The amount of metallic tin is not particularly limited as long as it is within the range of dissolving in each charged composition. However, if the amount of metal tin is too large, it takes time to dissolve or may remain undissolved. Therefore, when a tin halide compound is used as the tin compound, the dissolved tin metal and the tin halide compound are dissolved. It is preferable to determine the amount of metal tin dissolved such that the atomic ratio of halogen to tin is 0.60 or more and less than 1.80.

The tin oxide powder contains at least one element selected from the group consisting of alkaline earth metals, rare earth elements, transition elements, elements of Groups 13, 14, and 15 of the periodic table, and chalcogen elements or oxides thereof. When it is contained as a two-component element, an alkoxide, halide, oxychloride, nitrate, acetate, sulfate, or ammonium salt containing a desired second component element as an organic solvent-soluble compound is used as a tin compound and And / or dissolved in an organic solvent together with metallic tin to form a precursor solution.

When the second component element is an alkaline earth metal, halides and hydrates of the alkaline earth metal, nitrates and hydrates thereof, alkoxides and the like can be used.
It can be used without any particular limitation.

Specific compounds include CaCl ₂ , Ca
Br ₂ , CaI ₂ , CaCl ₂ .6H ₂ O, CaBr ₂ .6
_{H 2 O, CaI 2 · 6H} 2 O, Ca (NO 3) 2 · 4H 2 O,
Ca (NO ₃ ) ₂ .xH ₂ O, Ca (OCH ₃ ) ₂ , Ca
(OC ₂ H ₅ ) ₂ , Ca (OC ₃ H ₇ ) ₂ , Ca (OC ₄ H ₉ )
₂ , SrCl ₂ , SrBr ₂ , SrI ₂ , SrCl ₂ .6H ₂
O, SrBr ₂ .6H ₂ O, SrI ₂ .6H ₂ O, Sr (N
O ₃ ) ₂ , Sr (OCH ₃ ) ₂ , Sr (OC ₂ H ₅ ) ₂ , Sr
(OC ₃ H ₇ ) ₂ , Sr (OC ₄ H ₉ ) ₂ , BaCl ₂ , Ba
Br ₂ , BaI ₂ , BaCl ₂ .2H ₂ O, BaBr ₂ .2
H ₂ O, BaI ₂ · 2H ₂ O, Ba (NO ₃ ) ₂ , Ba (O
CH ₃ ) ₂ , Ba (OC ₂ H ₅ ) ₂ , Ba (OC ₃ H ₇ ) ₂ , B
a (OC ₄ H ₉ ) ₂ and the like.

When the second component element is a rare earth element, halides and hydrates of the rare earth elements, nitrates and hydrates thereof, alkoxides and the like can be used without any particular limitation.

As specific compounds, LaCl ₃ , La
Br ₃ , LaI ₃ , LaCl ₃ .7H ₂ O, La (NO ₃ ) ₃
6H ₂ O, La (OCH ₃ ) ₃ , La (OC ₂ H ₅ ) ₃ , L
a (OC ₃ H ₇ ) ₃ , CeCl ₃ , CeBr ₃ , CeI ₃ , C
_{eCl 3 · 6H 2 O, Ce} (NO 3) 3 · 6H 2 O, PrC
l ₃ , PrCl ₃ .7H ₂ O, Pr (NO ₃ ) ₃ .6H ₂ O,
Pr (OC ₃ H ₇ ) ₃ , NdCl ₃ , NdBr ₃ , NdCl ₃
・ 6H ₂ O, Nd (NO ₃ ) ₃・ 5H ₂ O, SmCl ₃・ x
H ₂ O, Sm (NO ₃ ) ₃ .xH ₂ O, Sm (OC
_{3 H 7) 3, EuCl 3} · 6H 2 O, Eu (NO 3) 3 · 6H 2
_{O, GdCl 3, GdCl 3 ·} 6H 2 O, Gd (NO 3) 3
_{· 5H 2 O, TbCl 3,} TbCl 3 · xH 2 O, Tb (N
O ₃ ) ₃ .xH ₂ O, DyCl ₃ , DyCl ₃ .xH ₂ O, D
_{y (NO 3) 3 · 5H} 2 O, Dy (OC 3 H 7) 3, HoCl
_{3, HoCl 3 · 6H 2 O} , Ho (NO 3) 3 · 5H 2 O, E
_{rCl 3 · 6H 2 O, Er} (NO 3) 3 · 5H 2 O, Er
(OC ₃ H ₇ ) ₃ , TmCl ₃ .6H ₂ O, Tm (NO ₃ ) _{3
· 5H 2 O, YbBr 3,} YbI 3, YbCl 3 · 6H
₂ O, Yb (NO ₃ ) ₃ .xH ₂ O, LuCl ₃ , Lu (N
O ₃ ) ₃ .xH ₂ O.

When the second component element is a transition element,
Transition element halides and hydrates, oxyhalides, acetates, nitrates and hydrates thereof, sulfates and hydrates thereof, ammonium salts, alkoxides of transition elements and the like are used without particular limitation. be able to.

As specific compounds, ScCl ₃ , Sc
_{Cl 3 · xH 2 O, Sc} (NO 3) 3 · xH 2 O, TiC
l ₄ , TiBr ₄ , Ti (OCH ₃ ) ₂ , Ti (OC ₂ H ₅ )
₂ , Ti (OC ₃ H ₇ ) ₂ , Ti (OC ₄ H ₉ ) ₂ , VBr ₃ ,
VCl ₂ , VCl ₃ , VCl ₄ , VOBr ₂ , VOBr ₃ ,
_{VOCl 3, VF 3, VF 4} , VF 5, VI 3 · 6H 2 O, V
O (OCH ₃ ) ₃ , VO (OC ₂ H ₅ ) ₃ , VO (OC
_{3 H 7) 3, VO (} OC 4 H 9) 3, CrCl 3, CrBr 3,
_{CrCl 3 · xH 2 O, CrBr} 3 · 6H 2 O, CrI 3 ·
xH ₂ O, Cr (CH ₃ COO) ₃ .xH ₂ O, MnC
l ₂ , MnBr ₂ , MnI ₂ , MnCl ₂ .4H ₂ O, Mn
_{Br 2 · 4H 2 O, MnI} 2 · 4H 2 O, Mn (NO 3) 2 ·
6H ₂ O, Mn (OC ₃ H ₇ ) ₂ , Mn (OC ₂ H ₅ ) ₂ , F
eBr ₂ , Fe ₂ Br · 6H ₂ O, FeBr ₃ , FeBr ₃
6H ₂ O, Fe (OH) (CH 3 COO) ₂ , FeCl
_{2, FeCl 3 · 6H 2 O} , FeCl 3, FeI 2, Fe
_{(NO 3) 3 · 9H 2} O, (NH 4) 2 Fe (SO 4) 2 · x
H ₂ O, (NH ₄ ) Fe (SO ₄ ) ₂ .xH ₂ O, Fe (O
CH ₃ ) ₃ , Fe (OC ₂ H ₅ ) ₃ , Fe (OC ₃ H ₇ ) ₃ , F
e (OC ₄ H ₉ ) ₃ , CoBr ₂ , CoBr ₂ .6H ₂ O, C
o (C ₂ H ₃ O ₂ ) ₂ .4H ₂ O, CoCl ₂ , CoCl _{2.
6H 2 O, CoI 2, Co} (NO 3) 2 · 6H 2 O, Co
(OC ₃ H ₇ ) ₂ , NiBr ₂ , NiBr ₂ .xH ₂ O, Ni
(CH ₃ COO) ₂ .xH ₂ O, NiCl ₂ , NiCl _{2.
6H 2 O, NiI 2, NiI} 2 · 6H 2 O, Ni (NO 3) 2
6H ₂ O, CuBr, CuBr ₂ , Cu (CH ₃ CO
_{O) 2, CuCl, CuCl 2} , CuCl 2 · 2H 2 O, C
u (NO ₃ ) ₂ .3H ₂ O, ZnBr ₂ , Zn (CH ₃ CO
_{O) 2 · 2H 2 O,} ZnCl 2, ZnI 2, Zn (NO 3) 2
6H ₂ O, Zn (OCH ₃ ) ₂ , Zn (OC ₂ H ₅ ) ₂ , Z
n (OC ₃ H ₇ ) ₂ , Zn (OC ₄ H ₉ ) ₂ , YBr ₃ , YC
_{l 3 · 6H 2 O, YCl} 3, Y (NO 3) 3 · 6H 2 O, Y
(OCH ₃ ) ₃ , Y (OC ₂ H ₅ ) ₃ , Y (OC ₃ H ₇ ) ₃ , Z
rBr ₄ , ZrCl ₄ , ZrI ₄ , ZrO (CH ₃ COO)
_{2, ZrOCl 2 · 8H 2 O} , ZrI 2 · xH 2 O, ZrO
_{(NO 3) 2 · 2H 2} O, Zr (SO 4) 2 · 4H 2 O, Zr
(OCH ₃ ) ₄ , Zr (OC ₂ H ₅ ) ₄ , Zr (OC
_{3 H 7) 4, Zr (} OC 4 H 9) 4, NbCl 5, NbOC
_{l 3, NbBr 5, NbF 5} , Nb (OCH 3) 5, Nb
(OC ₂ H ₅ ) ₅ , Nb (OC ₃ H ₇ ) ₅ , Nb (OC ₄ H ₉ )
₅ , MoBr ₂ , MoBr ₃ , MoCl ₅ , (NH ₄ ) ₆ Mo
_{7 O 24 · 4H 2 O,} Mo (OC 2 H 5) 5, RuCl 3 · H 2
_{O, PdCl 2 · 2H 2 O} , AgNO 3, CdBr 2 · 4H
_{2 O, CdBr 2, CdCl 2} · 5 / 2H 2 O, CdC
l ₂ , CdF ₂ , CdI ₂ , Cd (NO ₃ ) ₂ .4H ₂ O, H
_{fCl 4, HfOCl 2 · 8H 2} O, Hf (OCH 3) 4,
Hf (OC ₂ H ₅ ) ₄ , Hf (OC ₃ H ₇ ) ₄ , Hf (OC ₄
H ₉ ) ₄ , TaCl ₅ , TaBr ₅ , Ta (OCH ₃ ) ₅ , T
a (OC ₂ H ₅ ) ₅ , Ta (OC ₃ H ₇ ) ₅ , Ta (OC
_{4 H 9) 5, WCl 5} , WCl 6, WBr 6, W (OC 2 H 5)
₅ , W (OC ₃ H ₇ ) ₅ , ReCl ₃ , ReCl ₅ , OsCl
₃ , IrCl ₃ .3H ₂ O, IrCl ₃ , IrCl ₄ , Pt
_{Cl 4 · 5H 2 O, H} 2 PtCl 6 · nH 2 O, AuBr 3 ·
_{xH 2 O, AuCl 3 · xH} 2 O, AuHCl 4 · 4H
_{2 O, Hg 2 Br 2,} HgCl 2, Hg (NO 3) 2 · 2H 2
O, HgSO _{4 and the} like can be exemplified.

When the second component element is a group 13 element of the periodic table, halides and hydrates, ammonium salts, sulfates, organic acid salts, alkoxides, etc. of the group 13 elements of the periodic table are particularly preferred. It can be used without limitation.

As specific compounds, B ₂ O ₃ , (N
_{H 4) 2 O · 5B 2} O 3 · 8H 2 O, BCl 3, BBr 3, B
I ₃ , H ₃ BO ₃ , B (OCH ₃ ) ₃ , B (OC ₂ H ₅ ) ₃ , B
(OC ₃ H ₇ ) ₃ , B (OC ₄ H ₉ ) ₃ , AlBr ₃ , AlC
_{l 3 · 6H 2 O, AlCl} 3, AlI 3, Al (NO 3) 3 ·
9H ₂ O, Al ₂ (SO ₄ ) ₃ , Al ₂ (SO ₄ ) ₃ .nH
₂ O, Al (OCH ₃ ) ₃ , Al (OC ₂ H ₅ ) ₃ , Al (O
C ₃ H ₇ ) ₃ , Al (OC ₄ H ₉ ) ₃ , GaBr ₃ , GaC
l ₃ , GaI ₃ , Ga (NO ₃ ) ₃ .xH ₂ O, Ga ₂ (SO
₄ ) ₃ , Ga ₂ (SO ₄ ) ₃ .xH ₂ O, Ga (OCH ₃ ) ₃ ,
Ga (OC ₂ H ₅ ) ₃ , Ga (OC ₃ H ₇ ) ₃ , Ga (OC ₄
H ₉ ) ₃ , InBr ₃ , InCl ₃ , InCl ₃ .xH ₂ O,
InI ₃ , In (NO ₃ ) ₃ .xH ₂ O, In ₂ (S
O ₄ ) ₃ , In ₂ (SO ₄ ) ₃ .xH ₂ O, In (OC
_{H 3) 3, In (OC} 2 H 5) 3, In (OC 3 H 7) 3, In
(OC ₄ H ₉ ) ₃ , CH ₂ (COOTl) ₂ , TlOOCH
And the like.

When the second component element is a Group 14 element of the periodic table, halides and hydrates, ammonium salts, sulfates, organic acid salts, alkoxides and the like of the Group 14 elements are particularly preferred. It can be used without limitation.

As specific compounds, GeBr ₄ , Ge
Cl ₄ , GeI ₄ , Ge (OCH ₃ ) ₄ , Ge (OC ₂ H ₅ )
₄ , Ge (OC ₃ H ₇ ) ₄ , Ge (OC ₄ H ₉ ) _{4 and the} like. When silicon is contained as the second component element, the general formulas Si (OR _A ) ₄ and R _B Si
_{(OR A) 3, R B} R C Si silicon alkoxide represented by (OR _{A) 2} is used. Here, R _A , R _B , and R _C are each a linear or branched alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, and a pentyl group; an ethenyl group, a propenyl group, a butenyl group, and a pentenyl group. A linear or branched alkenyl group such as a group, and an aryl group such as a phenyl group.

Specific examples of silicon alkoxides include:
Tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane, methyltrimethoxysilane, ethyltrimethoxysilane, phenyltrimethoxysilane, propyltrimethoxysilane, n
-Butyltrimethoxysilane, isobutyltrimethoxysilane, n-hexyltrimethoxysilane, n-octadecyltrimethoxysilane, methyltriethoxysilane, ethyltriethoxysilane, amyltriethoxysilane, phenyltriethoxysilane, n-octyltriethoxysilane Silane, n-octadecyltriethoxysilane, n-dodecyltriethoxysilane, methyltributoxysilane, ethyltributoxysilane, ethyltripropoxysilane, vinyltriethoxysilane, allyltriethoxysilane, diphenyldimethoxysilane, dimethyldiethoxysilane, Examples include vinylmethyldiethoxysilane, diethyldimethoxysilane, and ethylmethyldiethoxysilane. As silicon halide,
SiCl ₄ , SiHCl ₃ , SiH ₂ Cl _{2 and the} like can be mentioned.

When the second component element is a Group 15 element of the periodic table, halides and hydrates, ammonium salts, sulfates, organic acid salts and alkoxides of the Group 15 elements of the periodic table, especially It can be used without limitation.

As specific compounds, P ₂ O ₅ , PB
r ₃ , PCl ₃ , POBr ₃ , POCl ₃ , PO (OC
_{H 3) 3, PO (OC} 2 H 5) 3, PO (OC 3 H 7) 3, PO
(OC ₄ H ₉ ) ₃ , P (OCH ₃ ) ₃ , P (OC ₂ H ₅ ) ₃ , A
sBr ₃ , AsCl ₃ , AsI ₃ , As (OCH ₃ ) ₃ , A
s (OC ₂ H ₅ ) ₃ , As (OC ₃ H 7) ₃ , SbBr ₃ , S
bCl ₃ , SbCl ₅ , SbOCl, Sb ₂ (SO ₄ ) ₃ ,
Sb (OCH ₃ ) ₃ , Sb (OC ₂ H ₅ ) ₃ , Sb (OC ₃ H
₇ ) ₃ , Sb (OC ₄ H ₉ ) ₃ , BiBr ₃ , BiCl ₃ , B
iI ₃ , Bi (NO ₃ ) ₃ .xH ₂ O, BiOCl, Bi
(OC ₃ H ₇ ) _{3 and the} like.

When the second component element is a chalcogen element, halides and hydrates of the chalcogen element, ammonium salts, sulfates, organic acid salts, alkoxides and the like can be used without any particular limitation. it can.
Specific compounds include S ₂ Cl ₂ , SCl ₂ , SeO ₂ ,
SeO ₂ , SeBr ₄ , SeCl ₄ , SeI ₄ , TeB
Examples thereof include r ₄ , TeCl ₄ , and TeO ₄ H ₂ .xH ₂ O.

The amount of the organic solvent-soluble compound to be added is not particularly limited. However, when represented by the atomic composition of the Sn atom and the second component element in the precursor solution, the Sn atom is 30.0 to 99.9.
It is preferable to mix the organic solvent-soluble compound so as to be in the range of atomic%.

The method for dissolving the organic solvent-soluble compound in the organic solvent is not particularly limited. For example, a method in which an organic solvent is added dropwise to a tin compound, metal tin, and an organic solvent-soluble compound of the second component element under stirring, or a tin compound, metal tin, and an organic solvent-soluble compound of the second component element are added to the organic solvent while stirring. Can be used simultaneously or sequentially. In order to promote the dissolution of metal tin, it is also effective to reflux the organic solvent to dissolve the metal tin.

Further, in order to accelerate the hydrolysis reaction, polymerization and condensation reaction of the organic solvent-soluble compound, some water may be added. The addition of water has effects such as sufficient progress of hydrolysis, polymerization and condensation reactions, particularly when preparing a precursor solution using an organic solvent-soluble compound such as an alkoxide. However, if the amount of water to be added is too large, precipitation occurs or gels rapidly,
There may be variations in the homogeneity of the composition and the like. The amount of water to be added is preferably 0.01 to 10 times as much as the molar amount of the organic solvent-soluble compound, though it varies depending on the kind of the organic solvent-soluble compound.

Further, for the purpose of controlling the pore diameter and the distribution of the obtained tin oxide powder, the precursor solution contains
A compound that is soluble in the organic solvent and has a higher boiling point than the organic solvent and that can be removed from the tin oxide powder by oxidization or the like during firing (hereinafter, also referred to as an organic solvent-soluble high-boiling compound) is added. May be. When a spherical gel is prepared from the precursor solution to which the organic solvent-soluble high-boiling compound is added, the organic solvent-soluble high-boiling compound is uniformly dispersed in the spherical gel. When such a spherical gel is fired to produce a spherical tin oxide powder, the organic solvent-soluble high-boiling compound is desorbed in the firing process, and it becomes possible to introduce pores into the tin oxide powder. The average pore radius, pore volume, and distribution of the pores thus formed can be controlled by the properties of the organic solvent-soluble high-boiling compound to be added and the amount thereof. Preferred organic solvent-soluble high-boiling compounds differ depending on the organic solvent used. For example, when the organic solvent is methanol, the weight average molecular weight is 100%.
It is preferable to add 0.1 to 50 parts by weight of polyethylene glycol of １００100,000 to the organic solvent-soluble compound in the precursor solution.

In the precursor solution prepared as described above,
A suspension is prepared by adding a suspending solvent that is incompatible with the organic solvent used to prepare the precursor solution.

The term "suspension solvent" as used herein means a solvent having a solubility in 100 ml of the above-mentioned organic solvent at room temperature (hereinafter referred to as "solubility") of about 50 g or less. It can be used without. A solvent having a solubility of more than 50 g is not preferable because a suspension may not be formed even when added to the precursor solution. Particularly preferred suspending solvents vary depending on the type of the organic solvent used for preparing the precursor solution, but when the organic solvent is methanol, for example, heptane, 3-methylheptane, octane, isooctane, nonane, ,
2,5-trimethylhexane, decane, cyclohexane, methylcyclohexane, petroleum ether, carbon disulfide and the like can be used. Further, a mixture of these solvents may be used as a suspending solvent.

The preferable addition amount of the suspending solvent to be added to the precursor solution is such that if the amount of the spherical solution dispersed in the suspension is too large, the dispersion state may not be stable. Since the yield of tin oxide powder per unit volume decreases, the volume is preferably 0.1 to 10 times, more preferably 0.5 to 5 times the volume of the precursor solution.

A suspension obtained by adding a suspending solvent to a precursor solution often has a structure in which the precursor solution is dispersed spherically in the suspending solvent. However, depending on the combination of the organic solvent and the suspending solvent, most of the soluble compounds dissolved in the precursor solution move into the suspending solvent,
In some cases, the suspension solvent in which the soluble compound is dissolved has a spherical structure dispersed in an organic solvent. Even when the suspension has such a structure, it is possible to produce the intended tin oxide powder.

As described above, the suspension of the present invention has a structure in which an organic solvent in which a soluble compound is dissolved is dispersed spherically in a suspension solution, or a suspension in which a soluble compound is dissolved is dissolved in an organic solvent. Takes a structure that disperses in a spherical shape Hereinafter, the spherically dispersed organic solvent or the spherically dispersed suspension solvent is collectively referred to as a spherical dispersion solution, and the suspended solvent or organic solvent in which the spherically dispersed solution is dispersed is generally referred to as a dispersion medium.

As a method for stabilizing the dispersion state of the suspension, widely known methods can be employed. For example, a method of adding a surfactant, a method of performing mechanical stirring, a method of irradiating ultrasonic waves, and the like can be used.
Further, the diameter of the solution of the soluble compound dispersed spherically in the suspension changes according to the conditions of these methods, and therefore the diameter of the tin oxide powder can be controlled according to the conditions.

Examples of the surfactant for stabilizing the dispersion state of the suspension include anionic surfactants such as sodium bis (ethylhexyl) sulfosuccinate, cationic surfactants such as cetyltrimethylammonium oxalate, and pentaethylene. A nonionic surfactant such as glycol dodecyl ether can be used.

Next, a spherical gel is prepared by gelling the spherical dispersion solution in the suspension. The precursor solution of the present invention often gels mainly as a hydroxide in an alkaline aqueous solution. Therefore, in a suspension in which the precursor solution is dispersed in the suspension solvent as a spherical dispersion solution, the spherical dispersion solution in the suspension can be gelled as follows. For example, a urea aqueous solution is added in advance to the precursor solution to prepare a suspension, and the suspension is heated to 60 ° C. or higher. At this time, NH ₃ is released from the urea, and the pH in the spherical dispersion solution increases, so that the soluble compound precipitates mainly as a hydroxide in the spherical dispersion solution, and a spherical gel can be obtained. Compounds having the same effect as urea include hexamethylenetetramine, formamide, and acetamide.

When an alkaline aqueous solution such as aqueous ammonia has a certain solubility in an organic solvent or a suspending solvent serving as a dispersion medium of the suspension, the alkaline aqueous solution is directly added to the suspension. The spherical dispersion solution can be gelled. The alkaline aqueous solution dissolved in the organic solvent or the suspending solvent serving as the dispersion medium of the suspension is dissolved in the spherical dispersion solution through the dispersion medium of the suspension, and the p in the spherical dispersion solution is dissolved.
By increasing H, the soluble compound is precipitated mainly as a hydroxide. Thereby, a spherical gel can be obtained.

Further, when an alkaline aqueous solution such as aqueous ammonia is hardly dissolved in the dispersion medium of the suspension, an alkaline aqueous solution or an alkaline aqueous solution prepared by adding an alkaline aqueous solution to the same solvent as the dispersion medium of the suspension is used. (Hereinafter referred to as an alkaline aqueous solution suspension)
By adding to the suspension, the spherical dispersion solution and the alkaline aqueous solution are both dispersed and suspended in the dispersion medium. By leaving the solution in such a state with stirring,
The spherical dispersion solution dispersed in this solution and the alkaline aqueous solution collide with each other and react to increase the pH in the spherical dispersion solution,
The soluble compound in the spherical dispersion solution is mainly gelled as a hydroxide to obtain a spherical gel.

The spherical gel thus obtained is separated from the suspension by a method such as filtration, dried if necessary, and then calcined to obtain spherical tin oxide powder.

The firing temperature for firing the spherical gel is 25.
The temperature is preferably from 0 to 1200 ° C. If the firing temperature is extremely higher or lower than this, the charge / discharge capacity of the obtained spherical tin oxide powder may decrease, which is not preferable. Therefore, a more preferable firing temperature is 500 to 1
100 ° C.

The firing time varies depending on the firing temperature, atmosphere, and the like, but the firing time is preferably 0.03 to 8 hours. The heating rate during firing is not particularly limited,
Preferably it is 0.1 to 100 ° C / min.

The atmosphere during firing is not particularly limited. For example, an atmosphere filled with an oxidizing gas such as air, oxygen, water vapor, or a mixed gas thereof, or an inert gas such as helium, neon, or argon, nitrogen, or a reducing gas such as hydrogen or carbon monoxide. Atmosphere and the like. However, in the case of an atmosphere of an inert gas or a reducing gas, there is a case where a large amount of metal tin is generated by being reduced in addition to tin oxide, or a large amount of organic matter remains and cycle characteristics are deteriorated. The atmosphere is an oxidizing gas atmosphere, and among them, an atmosphere containing oxygen is particularly preferable. Also, in order to improve cycle characteristics, once tin oxide is produced in an oxidizing gas atmosphere, the average valence of tin is adjusted in a reducing atmosphere to a range of more than 0 to 4 or less. Firing in an oxidizing gas atmosphere and firing in a reducing gas atmosphere can be combined.

The tin oxide powder thus produced is spherical. The spherical shape in the present invention means that the particles of the tin oxide powder have a spherical shape or a shape close to the spherical shape, and have an average uniformity of 0.66 to 1.00. Such a spherical tin oxide powder has a high filling density of the powder expressed as a tap density, which facilitates filling the negative electrode of the nonaqueous electrolyte secondary battery with the tin oxide powder at a high density. As a result, the charge / discharge capacity of the battery can be increased.

The above average uniformity Pa is the maximum width (major axis: L) of each of the n (n> 30) particles and the maximum width (minor axis) in a direction orthogonal to the major axis of the particles constituting the tin oxide powder. : B) and can be determined by the following equation 1.

[0067]

(Equation 1)

The diameter and the minor diameter are determined by, for example, taking an electron micrograph of the tin oxide powder and measuring the major and minor diameters of the particles constituting the tin oxide powder observed in a unit field of view of the photograph. Can be.

In the production method of the present invention, the average particle size of the tin oxide powder is determined by the presence or absence of surfactant, its amount, type, presence or absence of ultrasonic irradiation, its conditions, Tin oxide powder having an average particle diameter in the range of 0.01 to 100 μm can be produced, depending on whether or not stirring is performed, conditions thereof, and the like. A more preferable range of the average particle diameter is 0.1 to 50 μm. The above average particle diameter D is obtained by the following equation 2.

[0070]

(Equation 2)

The composition of the tin oxide powder produced according to the present invention varies depending on the type and amount of the organic solvent-soluble compound added, but the second component element is uniformly distributed in the tin oxide. The composition is often maintained even in tin oxide powder. The types and contents of elements contained in tin oxide are identified by chemical analysis or fluorescent X-ray analysis, etc.
It can be quantified.

The structure of the tin oxide produced according to the present invention may be either crystalline tin oxide or amorphous tin oxide depending on the firing conditions and the second component element.

When the tin oxide of the present invention is crystalline, its crystal structure is the same as that of tin dioxide JCP.
Tetragonal tin dioxide described in DS Card 21-1250, 2
9-1484, orthorhombic tin dioxide, 33-1374
It may have a crystal structure such as the cubic tin dioxide described. In some cases, the crystal structure of ditin trioxide having the crystal structure described in JCPDS card 25-1259 is adopted.
In some cases, a crystal structure of tritin tetroxide having a crystal structure described in JCPDS card 20-1293 is used. Also, a JCPDS card 6 which is a crystal structure of tin monoxide is used.
In some cases, the crystal structure may take the form of tetragonal tin monoxide described in 395, tin monoxide having the crystal structure described in 7-195, or orthorhombic tin monoxide described in 24-1342. Further, two or more types of tin oxide having the above-mentioned crystal structure may be contained in an arbitrary ratio.

The structure of tin oxide can be determined based on the position and intensity of a diffraction peak obtained by a powder X-ray diffraction method, an electron beam diffraction method or the like. The position and intensity of the diffraction peak of powder X-ray diffraction are tin, solid solution of elements other than oxygen,
Although there may be a slight variation due to crystal orientation, etc., the crystal structure of tin oxide is determined by comparing the intensity and the diffraction peak position of tin oxide registered in the above-mentioned JCPDS card or the like. be able to.

BE of tin oxide powder produced according to the present invention
The specific surface area measured by the T method varies depending on the firing conditions and the production conditions such as the second component element.
It is often in the range of ² / g.

The typical pore structure of the tin oxide powder produced according to the present invention has an average pore radius of 0.05 to 25 n.
m in the range of 0.01 to 1.0 cm ³ /
g, and the volume of such pores is 1% of the total pore volume.
Often accounts for more than 5%. These average pore radii,
The pore volume can be measured by a mercury intrusion method, a gas adsorption method, an X-ray small angle scattering method, a high voltage electron microscope, or the like.

When the spherical tin oxide powder produced by the production method of the present invention is crystalline, the typical crystallite size is 1 to 300 nm. The crystallite size can be determined by the Scherrer's method from the spread of the diffraction peaks observed by powder X-ray diffraction and the like (Carity, translated by Gentaro Matsumura, "New Edition X-ray Diffraction Guideline", 91, Agne, 1985). . Further, it can be confirmed by direct observation with a transmission electron microscope or the like.

In the spherical tin oxide powder produced according to the present invention, the spherical tin oxide powder obtained by dispersing the second component element uniformly is often formed of a single phase. (A) composed of tin oxide having a thickness of 1 to 30 nm and (B) composed of an oxide of a second component element such as silicon oxide.
It may have a phase structure. In particular,
A structure in which the (A) phase having a maximum diameter of 1 μm or less is precipitated using the (B) phase as a mother phase, or a maximum diameter of 1 μm using the (A) phase as a mother phase.
m or less (B) phase may precipitate. Such a fine structure can be observed with a transmission electron microscope or the like, and the size can be measured by small angle X-ray scattering or the like.

The spherical tin oxide powder produced according to the present invention can be used as it is as a negative electrode active material for a non-aqueous electrolyte secondary battery, but the difference between the initial charge capacity and discharge capacity (also referred to as irreversible capacity). In order to reduce the size of the tin oxide, lithium can be previously stored in the tin oxide.
As a method for producing tin oxide to be described later, a method in which a lithium compound corresponding to an irreversible capacity is simultaneously added to form a compound in tin oxide, or in an organic electrolyte solution in which a lithium salt is dissolved. For example, a method of electrochemically inserting lithium into tin oxide using lithium metal or a lithium alloy as a counter electrode can be adopted.

It is also possible to modify the surface of tin oxide to reduce the irreversible capacity. For example, only the tin oxide surface can be changed to SnO, or carbon coating can be performed. Further, if only the surface layer is changed to Sn, the irreversible capacity may be effectively reduced.

The spherical tin oxide powder having an average degree of uniformity of 0.66 to 1.00 produced by the present invention has a sufficiently high packing density even if the particle size distribution is monodisperse, so that it can be filled. Although it is effective in improving the discharge capacity, in order to further improve the packing density, it is effective to adjust the particle size distribution to a binomial distribution or a polynomial distribution more than that. Control methods may be used together.

When the spherical tin oxide powder produced as described above is used as a negative electrode active material for a non-aqueous electrolyte secondary battery,
The configuration and manufacture of the nonaqueous electrolyte secondary battery can be performed by a known method. A typical manufacturing method is described below.

First, tin oxide and / or composite tin oxide is kneaded with a solvent such as N-methylpyrrolidone using a kneader or a mixer to produce a paste. At this time, a conductivity-imparting agent such as graphite or acetylene black, or a binder such as polytetrafluoroethylene or polyvinylidene fluoride may be appropriately added.

After the paste is manufactured, the current collector is coated, filled or impregnated with the paste, and the solvent is dried and removed.
Pressing, cutting, and the like are performed to form a desired shape to obtain a negative electrode. The negative electrode and the positive electrode manufactured in the same manner are stacked in a strip shape with a separator interposed therebetween, and wound in a cylindrical shape in the case of a cylindrical non-aqueous electrolyte secondary battery, and folded in the case of a square non-aqueous electrolyte secondary battery. The electrode portion is manufactured by overlapping. Thereafter, the electrode portion is inserted into a desired battery container, a non-aqueous electrolyte is injected, a safety device or the like is inserted, and the can is sealed.

For the positive electrode, the current collector, the non-aqueous electrolyte, the separator, and the like, materials used in conventional non-aqueous electrolyte secondary batteries are used without any problem.

As the positive electrode active material, TiS ₂ , MoS ₂ ,
Chalcogen compounds such as sulfides such as FeS ₂ , selenides such as NbSe ₃ , or Cr ₂ O ₅ , Cr ₃ O ₈ , V
Oxides of transition metals such as ₃ O ₈ , V ₂ O ₅ , V ₆ O ₁₃ , Li
Mn ₂ O ₄ , LiMnO ₂ , LiV ₃ O ₅ , LiNiO ₂ , L
a composite oxide of lithium and a transition metal such as iCoO ₂ , or polyaniline, polyacetylene, polyparaphenylene, polyphenylenevinylene, polypyrrole,
A material capable of inserting and extracting lithium, such as a conjugated polymer such as polythiophene or a crosslinked polymer having a disulfide bond, may be used.

As the current collector, a band-shaped thin plate or mesh made of copper, aluminum, or the like may be used.

Examples of the non-aqueous electrolyte include propylene carbonate, ethylene carbonate, 1,2-dimethoxyethane, 1,2-diethoxyethane, γ-butyrolactone,
LiClO ₄ , LiPF ₆ may be used alone or as a mixture of two or more kinds of non-aqueous solvents such as tetrahydrofuran, 1,3-dioxolan, 4-methyl-1,3-dioxolan, diethyl ether, sulfolane, methylsulfolane, acetonitrile, propionitrile and the like. , LiAsF ₆ , LiB
F ₄ , LiB (C ₆ H ₅ ) ₄ , LiCl, LiBr, CH _{3
SO 3 Li, CF 3 SO 3} Li nonaqueous electrolyte lithium salt is dissolved, such as can be also be used in any combination.

As the separator, a separator having low resistance to the movement of ions and excellent in solution retention may be used. For example, a polymer pore filter made of polypropylene, polyethylene, polyester, polyflon, or the like, a glass fiber filter, a nonwoven fabric, or a nonwoven fabric made of glass fibers and these polymers can be used. Further, when the temperature inside the battery becomes high, a material that melts to close the pores and prevent short circuit between the positive electrode and the negative electrode is preferable.

[0090]

According to the present invention, the raw materials of tin and the second component element are dispersed in a spherical state in a solution state, and then gelled and fired.
It has become possible to produce spherical tin oxide powder uniformly containing a wide range of second component elements. As a result, tin oxide powder having a composition suitable as a negative electrode active material of a non-aqueous electrolyte secondary battery having a high charge / discharge capacity can be filled into a negative electrode at a high density, thereby increasing the charge / discharge capacity of the battery. It became possible.

[0091]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

The measurement of the discharge capacity shown in the following Examples and Comparative Examples was performed as follows.

Tin oxide, polyvinylidene fluoride (binder)
And acetylene black (conductivity imparting agent) at 80/5
/ 15 (weight ratio).
To 1 g, 1 ml of N-methylpyrrolidone was added and kneaded to prepare a paste. This paste was dried in a vacuum dryer at 100 ° C. for 24 hours. Dry paste 6m
g was applied to a nickel mesh to form a negative electrode. The non-aqueous electrolyte was used after dissolving LiCl0 ₄ (concentration of 1 mol / liter) in an equal volume mixed solvent of ethylene carbonate and diethyl car sulfonates. A glass container is used for the battery container, and two positive electrodes (using lithium) are placed on both sides of one negative electrode, and one reference electrode (using lithium) is arranged near the negative electrode. A simple battery cell was constructed by suspending from the lid with a nickel wire with a clip (covered with a glass tube).

Using a charge / discharge device (manufactured by Hokuto Denko), a charge / discharge cycle test was performed on the above-described simplified battery cell, and the charge / discharge capacity of the negative electrode active material was measured. In the charge / discharge cycle test,
The test was performed at a current value (constant) corresponding to 30 mA / g. The discharge capacity of the negative electrode active material was calculated from the capacity = 30 × t (unit; mAh / g) by measuring the discharge time t (unit: time). The charge / discharge is 0 to the reference electrode.
The test was performed within a range of 1.99V. Note that the discharge capacities shown in Examples and Comparative Examples indicate the discharge capacities at the time of the first discharge.

Example 1 7.58 g (0.04 mol) of stannous chloride (SnCl ₂ ) and 4.75 g (0.04 mol) of tin metal were refluxed in 38.5 g (1.20 mol) of methanol. While dissolving the precursor solution sequentially to prepare a uniform and transparent precursor solution. A urea aqueous solution in which 14 g of urea was dissolved in 20 ml of water was added to this precursor solution, and then 50 ml of cyclohexane was added to obtain a suspension in which the precursor solution containing the urea aqueous solution was dispersed in a spherical shape. This suspension was heated at 60 ° C. for 12 hours to gel the precursor solution to obtain a powdery gel. The obtained gel was calcined in air at 700 ° C. for 2 hours using an electric furnace to obtain tin oxide powder.

As a result of powder X-ray diffraction, it was confirmed that the obtained tin oxide powder was crystalline tin oxide having a rutile structure.

When the obtained tin oxide powder was observed by SEM, the tin oxide powder was spherical particles having an average uniformity of 0.95 and a substantially uniform particle diameter of about 3.2 μm.

This spherical tin oxide powder has a tap density of 3.6.
g / cm and ³ high, it was possible to fill with a high packing density when preparing a negative electrode by the method. Further, the simplified battery cell was fabricated and subjected to a charge / discharge cycle test. As a result, the discharge capacity was 710 mAh / g.

Example 2 7.55 g (0.04 mol) of stannous chloride (SnCl ₂ ), 4.75 g (0.04 mol) of metallic tin, 38.5 g (1.20 mol) of methanol and trichloride Antimony (Sb
0.96 g (0.0042 mol) of Cl ₃ were sequentially dissolved under reflux to prepare a uniform and transparent precursor solution.
A urea aqueous solution in which 14 g of urea was dissolved in 20 ml of water was added to this precursor solution, and then 50 ml of cyclohexane was added to obtain a suspension in which the precursor solution containing the urea aqueous solution was dispersed in a spherical shape. This suspension was heated at 60 ° C. for 12 hours to gel the precursor solution to obtain a powdery gel. The obtained gel was baked in an electric furnace at 700 ° C. for 2 hours in air to obtain tin oxide powder. As a result of powder X-ray diffraction, the obtained tin oxide powder was crystalline tin oxide having a rutile structure. Was. Further, since no diffraction X-ray peak due to antimony oxide was detected, it was found that antimony oxide was dissolved in tin oxide.

According to the fluorescent X-ray analysis, the ratio of tin to antimony in the tin oxide powder was almost equal to the charging ratio.

Observation of the obtained tin oxide powder by SEM revealed that the tin oxide powder was spherical particles having an average uniformity of 0.93 and a substantially uniform particle diameter of about 2.8 μm.

This spherical tin oxide powder has a tap density of 3.
As high as 9 g / cm ³ , it was possible to fill at a high packing density when the negative electrode was produced by the above-described method. Further, the simplified battery cell was fabricated and subjected to a charge / discharge cycle test. As a result, the discharge capacity was 717 mAh / g.

Example 3 0.96 g (0.00%) of antimony trichloride (SbCl ₃ )
42 mol) instead of antimony trichloride (SbCl ₃ )
A tin oxide powder was obtained in the same manner as in Example 2 except that 2.97 g (0.013 mol) was used.

As a result of powder X-ray diffraction, the obtained tin oxide was a crystalline tin oxide having a rutile structure. Further, since no diffraction X-ray peak due to antimony oxide was detected, it was found that antimony oxide was dissolved in tin oxide.

According to the fluorescent X-ray analysis, the ratio of tin to antimony in the tin oxide powder was almost equal to the charged ratio.

When the obtained tin oxide powder was observed by SEM, it was found that the tin oxide powder was spherical particles having an average uniformity of 0.90 and a substantially uniform particle diameter of about 2.6 μm.

The spherical tin oxide powder has a tap density of 3.
It was as high as 7 g / cm ^3, and it was possible to fill at a high packing density when the negative electrode was produced by the above method. Further, the simplified battery cell was fabricated and subjected to a charge / discharge cycle test. As a result, the discharge capacity was 715 mAh / g.

Example 4 0.96 g (0.00%) of antimony trichloride (SbCl ₃ )
42 mol) instead of tetraethoxysilane (Si (0
_{C 2 H 5) 4) 7.1g} ( but using 0.034 mole) to give a tin oxide powder in the same manner as in Example 2.

As a result of powder X-ray diffraction, the obtained tin oxide was a crystalline tin oxide having a rutile structure. No diffraction X-ray peak due to silicon oxide was particularly observed.

As a result of observation with a transmission electron microscope, it was confirmed that the amorphous silicon oxide was uniformly distributed among the tin oxide particles, that is, the dispersed phase was a phase composed of tin oxide.
As a result of obtaining the average region diameter of the dispersed phase by the small-angle X-ray scattering method, it was about 10 nm.

According to the fluorescent X-ray analysis, the ratio of tin to silicon in the tin oxide powder was almost equal to the charging ratio.

When the obtained tin oxide powder was observed by SEM, the tin oxide powder was spherical particles having an average uniformity of 0.96 and a substantially uniform particle diameter of about 3.3 μm.

This spherical tin oxide powder has a tap density of 4.
Since it was 0 g / cm ³ higher, it was possible to fill at a high packing density when the negative electrode was manufactured by the above method. Further, the simplified battery cell was fabricated and subjected to a charge / discharge cycle test. As a result, the discharge capacity was 732 mAh / g.

Example 5 Stannous chloride (SnCl ₂ ) 7.58 g (0.04 mol), metallic tin 4.75 g (0.04 mol), antimony trichloride (SbCl ₃ ) 0.96 g (0.0042) Mole)
And tetraethoxysilane (Si (0C ₂ H ₅ ) ₄ )
3.3 g (0.016 mol) of methanol 38.5 g
(1.20 mol), except that tin oxide powder was obtained in the same manner as in Example 2.

As a result of powder X-ray diffraction, the obtained tin oxide was a crystalline tin oxide having a rutile structure. No diffraction X-ray peak due to silicon oxide or antimony oxide was particularly observed.

According to the fluorescent X-ray analysis, the ratio of tin to silicon and the ratio of tin to antimony in the tin oxide powder were almost equal to the charging ratio.

Observation of the obtained tin oxide powder by SEM revealed that the tin oxide powder was spherical particles having an average uniformity of 0.95 and a substantially uniform particle diameter of about 3.4 μm.

This spherical tin oxide powder has a tap density of 4.
As high as 2 g / cm ³ , it was possible to fill at a high packing density when the negative electrode was produced by the above-described method. Further, the simplified battery cell was fabricated and subjected to a charge / discharge cycle test. As a result, the discharge capacity was 735 mAh / g.

Example 6 0.96 g (0.00%) of antimony trichloride (SbCl ₃ )
42 mol) instead of trimethoxyboron (B (OCH
₃ ) ₃ ) 4.14 g (0.040 mol) and triethoxyphosphoryl (PO (OEt) ₃ ) 7.29 g (0.20 g).
040 mol), and baked in air at 280 ° C. for 1 hour to obtain a tin oxide powder in the same manner as in Example 2.

As a result of powder X-ray diffraction, the obtained tin oxide was amorphous.

According to the fluorescent X-ray analysis, the ratio of tin to boron and the ratio of tin to phosphorus in the tin oxide powder almost coincided with the charging ratio.

When the obtained tin oxide powder was observed by SEM, the tin oxide powder was spherical particles having an average uniformity of 0.89 and a substantially uniform particle diameter of about 3.1 μm.

This spherical tin oxide powder has a tap density of 3.
It was as high as 8 g / cm ^3, and it was possible to fill at a high packing density when the negative electrode was produced by the above method. Further, the simplified battery cell was fabricated and subjected to a charge / discharge cycle test. As a result, the discharge capacity was 712 mAh / g.

Example 7 Stannous chloride (SnCl ₂ ) 7.58 g (0.04 mol), metal tin 4.75 g (0.04 mol), antimony trichloride (SbCl ₃ ) 0.96 g (0.0042 mol) Mole)
In addition to and _{La (NO 3) 3 · 6H} 2 O1.73g (0.0
04 mol) was dissolved in 38.5 g (1.20 mol) of methanol to obtain a tin oxide powder in the same manner as in Example 2.

As a result of powder X-ray diffraction, the obtained tin oxide was a crystalline tin oxide having a rutile structure. No diffraction X-ray peak due to antimony oxide or lanthanum oxide was detected, indicating that antimony oxide or lanthanum oxide was dissolved in tin oxide.

According to the fluorescent X-ray analysis, the ratio of tin to antimony and the ratio of tin to lanthanum in the tin oxide powder were almost equal to the charging ratio.

Observation of the obtained tin oxide powder by SEM revealed that the tin oxide powder was spherical particles having an average uniformity of 0.92 and a substantially uniform particle diameter of about 2.6 μm.

The spherical tin oxide powder has a tap density of 3.
It was as high as 6 g / cm ^3, and it was possible to fill at a high packing density when the negative electrode was produced by the above method. Further, the simplified battery cell was fabricated and subjected to a charge / discharge cycle test. As a result, the discharge capacity was 714 mAh / g.

Example 8 7.58 g (0.04 mol) of stannous chloride (SnCl ₂ ), 4.75 g (0.04 mol) of tin metal, 0.96 g (0.0042 g) of antimony trichloride (SbCl ₃ ) Mole)
Plus triethoxyphosphoryl (PO (OEt) ₃ )
0.73 g (0.004 mol) of methanol 38.5 g
(1.20 mol), except that tin oxide powder was obtained in the same manner as in Example 2.

As a result of powder X-ray diffraction, the obtained tin oxide was a crystalline tin oxide having a rutile structure. Further, since no diffraction X-ray peak due to antimony oxide or lanthanum oxide was detected, it was found that antimony oxide and phosphorus oxide were dissolved in tin oxide.

According to the fluorescent X-ray analysis, the ratio of tin to antimony and the ratio of tin to phosphorus in the tin oxide powder almost coincided with the charging ratio.

Observation of the obtained tin oxide powder by SEM revealed that the tin oxide powder was spherical particles having an average uniformity of 0.87 and a very uniform particle diameter of about 3.6 μm.

This spherical tin oxide powder has a tap density of 3.
It was as high as 4 g / cm ^3, and it was possible to fill at a high packing density when the negative electrode was produced by the above method. Further, the simplified battery cell was fabricated and subjected to a charge / discharge cycle test. As a result, the discharge capacity was 718 mAh / g.

Example 9 0.96 g (0.00%) of antimony trichloride (SbCl ₃ )
Instead of the same mole of tantalum pentachloride (Ta).
Cl ₅₎ except using obtain a tin oxide powder in the same manner as in Example 2.

As a result of powder X-ray diffraction, the obtained tin oxide was a crystalline tin oxide having a rutile structure. Further, since no diffraction X-ray peak due to tantalum oxide was detected, it was found that tantalum oxide was dissolved in tin oxide.

According to the fluorescent X-ray analysis, the ratio of tin to tantalum in the tin oxide powder was almost equal to the charging ratio.

When the obtained tin oxide powder was observed by CEM, the tin oxide powder was spherical particles having an average uniformity of 0.85 and a substantially uniform particle diameter of about 2.9 μm.

The spherical tin oxide powder has a tap density of 3.
It was as high as 7 g / cm ^3, and it was possible to fill at a high packing density when the negative electrode was produced by the above method. Further, the simplified battery cell was fabricated and subjected to a charge / discharge cycle test. As a result, the discharge capacity was 705 mAh / g.

Example 10 0.96 g (0.00%) of antimony trichloride (SbCl ₃ )
Instead of the same mole of niobium pentachloride (NbC
l ₅₎ except using obtain a tin oxide powder in the same manner as in Example 2.

As a result of powder X-ray diffraction, the obtained tin oxide was a crystalline tin oxide having a rutile structure. Further, since no diffraction X-ray peak due to tantalum oxide was detected, it was found that niobium oxide was dissolved in tin oxide.

According to the fluorescent X-ray analysis, the ratio of tin to niobium in the tin oxide powder was almost equal to the charging ratio.

Observation of the obtained tin oxide powder by SEM revealed that the tin oxide powder was spherical particles having an average uniformity of 0.88 and a substantially uniform particle diameter of about 2.8 μm.

The spherical tin oxide powder has a tap density of 3.
It was as high as 5 g / cm ^3, and it was possible to fill at a high packing density when the negative electrode was produced by the above method. Further, the simplified battery cell was fabricated and subjected to a charge / discharge cycle test. As a result, the discharge capacity was 707 mAh / g.

Example 11 0.96 g (0.00%) of antimony trichloride (SbCl ₃ )
Instead of magnesium chloride (MgC
l ₂ ) A tin oxide powder was obtained in the same manner as in Example 2 except that 0.76 g (0.008 mol) was used.

As a result of powder X-ray diffraction, the obtained tin oxide was a crystalline tin oxide having a rutile structure. Further, since no diffraction X-ray peak due to magnesium oxide was detected, it was found that magnesium oxide was dissolved in tin oxide.

According to the fluorescent X-ray analysis, the ratio of tin to magnesium in the tin oxide powder was almost equal to the charging ratio.

When the obtained tin oxide powder was observed by SEM, the tin oxide powder was spherical particles having an average uniformity of 0.83 and a substantially uniform particle diameter of about 2.5 μm.

This spherical tin oxide powder has a tap density of 3.
It was as high as 6 g / cm ^3, and it was possible to fill at a high packing density when the negative electrode was produced by the above method. Further, the simplified battery cell was fabricated and subjected to a charge / discharge cycle test. As a result, the discharge capacity was 700 mAh / g.

Example 12 0.96 g (0.00%) of antimony trichloride (SbCl ₃ )
Instead of trimethoxyboron (B (OC
A tin oxide powder was obtained in the same manner as in Example 2 except that 0.83 g (0.008 mol) of H ₃ ) ₃ ) was used.

As a result of powder X-ray diffraction, the obtained tin oxide was a crystalline tin oxide having a rutile structure. Further, since no diffraction X-ray peak due to boron oxide was detected, it was found that boron oxide was dissolved in tin oxide.

According to the fluorescent X-ray analysis, the ratio of tin to boron in the tin oxide powder was almost equal to the charged ratio.

Observation of the obtained tin oxide powder by SEM revealed that the tin oxide powder was spherical particles having an average uniformity of 0.86 and a substantially uniform particle diameter of about 2.8 μm.

The spherical tin oxide powder has a tap density of 3.
It was as high as 8 g / cm ^3, and it was possible to fill at a high packing density when the negative electrode was produced by the above method. Further, the simplified battery cell was fabricated and subjected to a charge / discharge cycle test. As a result, the discharge capacity was 710 mAh / g.

Example 13 0.96 g (0.00%) of antimony trichloride (SbCl ₃ )
42 mol) instead of selenium tetrachloride (SeCl ₄ )
A tin oxide powder was obtained in the same manner as in Example 2 except that 1.62 g (0.008 mol) was used.

As a result of powder X-ray diffraction, the obtained tin oxide was a crystalline tin oxide having a rutile structure. Further, since no diffraction X-ray peak due to selenium was detected, it was found that selenium was dissolved in tin oxide.

According to the fluorescent X-ray analysis, the ratio of tin to selenium in the tin oxide powder was almost equal to the charging ratio.

Observation of the obtained tin oxide powder by SEM revealed that the tin oxide powder was spherical particles having an average uniformity of 0.86 and a substantially uniform particle diameter of about 2.8 μm.

This spherical tin oxide powder has a tap density of 3.
It was as high as 7 g / cm ^3, and it was possible to fill at a high packing density when the negative electrode was produced by the above method. Further, the simplified battery cell was fabricated and subjected to a charge / discharge cycle test. As a result, the discharge capacity was 710 mAh / g.

Example 14 A tin oxide powder was obtained in the same manner as in Example 2 except that 50 ml of octane was used instead of 50 ml of cyclohexane.

As a result of powder X-ray diffraction, the obtained tin oxide was a crystalline tin oxide having a rutile structure. Further, since no diffraction X-ray peak due to antimony oxide was detected, it was found that antimony oxide was dissolved in tin oxide.

According to the fluorescent X-ray analysis, the ratio of tin to antimony in the tin oxide powder was almost equal to the charging ratio.

Observation of the obtained tin oxide powder by SEM revealed that the tin oxide powder was spherical particles having an average uniformity of 0.87 and a substantially uniform particle diameter of about 2.6 μm.

This spherical tin oxide powder has a tap density of 3.
It was as high as 8 g / cm ^3, and it was possible to fill at a high packing density when the negative electrode was produced by the above method. Further, the simplified battery cell was fabricated and subjected to a charge / discharge cycle test. As a result, the discharge capacity was 720 mAh / g.

Example 15 7.58 g (0.04 mol) of stannous chloride (SnCl ₂ ), 4.75 g (0.04 mol) of tin metal, and trichloride in 38.5 g (1.20 mol) of methanol Antimony (Sb
0.96 g (0.0042 mol) of Cl ₃ were sequentially dissolved under reflux to prepare a uniform and transparent precursor solution.
50 ml of cyclohexane was added to this precursor solution to obtain a suspension in which the precursor solution was dispersed in a spherical shape. To this suspension was added 30 g of 28% aqueous ammonia to 50 m of cyclohexane.
of the precursor solution was vigorously stirred at room temperature for 12 hours to gel the precursor solution to obtain a powdery gel. The obtained gel was baked at 700 ° C. for 2 hours in the air using an electric furnace to obtain tin oxide powder. As a result of powder X-ray diffraction, the obtained tin oxide was a crystalline tin oxide having a rutile structure. . Further, since no diffraction X-ray peak due to antimony oxide was detected, it was found that antimony oxide was dissolved in tin oxide.

According to the fluorescent X-ray analysis, the ratio of tin to antimony in the tin oxide powder was almost equal to the charging ratio.

Observation of the obtained tin oxide powder by SEM revealed that the tin oxide powder was spherical particles having an average uniformity of 0.85 and a substantially uniform particle diameter of about 2.8 μm.

The spherical tin oxide powder has a tap density of 3.
It was as high as 7 g / cm ^3, and it was possible to fill at a high packing density when the negative electrode was produced by the above method. Further, the simplified battery cell was fabricated and subjected to a charge / discharge cycle test. As a result, the discharge capacity was 715 mAh / g.

[0168] Comparative Example 1 n-octanol 153.6 g (1.20 mol) tin tetrabutoxide (Sn (O-n-C 4 H 9) 4) 4.1g
(0.01 mol), 0.36 g (0.001) of SbCl ₃
6 mol) and refluxed to obtain a uniform solution. 0.1 g of hydroxypropylcellulose and 40 ml of acetonitrile were added to this solution to obtain a suspension. To this, 5mol
The alkoxide was hydrolyzed and gelled by adding 100 ml of an octanol / butanol mixed solution (volume ratio; 1: 1) containing 1 / l of water. The powder obtained by drying this gel was calcined in air at 1000 ° C. for 2 hours to obtain a white powder.

As a result of powder X-ray diffraction, the obtained powder was a mixture of crystalline tin oxide having a rutile structure and antimony oxide.

Observation of the powder by SEM revealed that the powder was a mixture of spherical particles having a particle size of about 0.2 μm and irregular-sized particles having a size of about 1 μm. As a result of analyzing the composition of these particles, the spherical particles are tin oxide,
The irregular-sized particles were found to be antimony oxide.

From the results, it was found that a spherical tin oxide powder having a uniform composition could not be obtained.

[0172] Comparative Example 2 n-octanol 153.6 g (1.20 mol) tin tetrabutoxide (Sn (O-n-C 4 H 9) 4) 4.1g
(0.01 mol), B (OC ₂ H ₅ ) ₃ 0.74 g (0.
0050 mol) and 0.90 g of PO (OC ₂ H ₅ ) ₃
(0.0050 mol) and refluxed to obtain a uniform solution. To this solution was added hydroxypropyl cellulose 0.1
g and 40 ml of acetonitrile were added to obtain a suspension.
To this, 100 ml of an octanol / butanol mixed solution (volume ratio: 1: 1) containing 5 mol / l of water was added to hydrolyze and gel the alkoxide. The powder obtained by drying this gel was calcined in air at 700 ° C. for 2 hours to obtain a white powder.

As a result of powder X-ray diffraction, the obtained powder was a mixture of crystalline tin oxide having a rutile structure and boron oxide.

Observation of this powder with a SEM revealed that the powder was a mixture of spherical particles having a particle size of about 0.2 μm and irregular-sized particles having a size of about 1 μm. As a result of analyzing the composition of these particles, it was found that the spherical particles were tin oxide containing phosphorus and the irregular-sized particles were boron oxide.

From the results, it was found that a spherical tin oxide powder having a uniform composition could not be obtained.

Comparative Example 3 To 153.6 g (1.20 mol) of n-octanol was added 4.1 g of tin tetrabutoxide (Sn (On-C ₄ H ₉ ) ₄ ).
(0.01 mol), 0.19 g of TaCl ₅ (0.000
(53 mol) and refluxed, but TaCl3 did not dissolve. To this solution was added hydroxypropylcellulose 0.
1 g and 40 ml of acetonitrile were added to obtain a suspension. To this was added 100 ml of a mixed solution of octanol / butanol (volume ratio: 1: 1) containing 5 mol / l of water to hydrolyze the alkoxide and gel it. The powder obtained by drying this gel was calcined in air at 700 ° C. for 2 hours to obtain a white powder.

As a result of powder X-ray diffraction, the obtained powder was a mixture of crystalline tin oxide having a rutile structure and tantalum oxide.

Observation of the powder by SEM revealed that the powder was a mixture of spherical particles having a particle size of about 0.2 μm and irregular-sized particles having a size of about 1 μm. As a result of analyzing the composition of these particles, it was found that the spherical particles were tin oxide containing phosphorus and the irregular-sized particles were tantalum oxide.

From the results, it was found that a spherical tin oxide powder having a uniform composition could not be obtained.

Claims (3)

[Claims] An organic solvent-soluble tin compound and / or metallic tin, an organic solvent-soluble alkaline earth metal compound, an organic solvent-soluble rare earth element compound, an organic solvent-soluble transition element compound, and an organic solvent-soluble periodic table group 13 element compound ,
At least one soluble compound selected from the group consisting of organic solvent-soluble periodic table group 14 element compounds (excluding organic solvent-soluble tin compounds), organic solvent-soluble periodic table group 15 element compounds, and organic solvent-soluble chalcogen element compounds To a solution dissolved in an organic solvent, a suspending solvent incompatible with the organic solvent is added, and the organic solvent in which the soluble compound is dissolved is dispersed in the suspending solvent, or the suspending solvent in which the soluble compound is dissolved is the organic solvent. A method for producing a spherical tin oxide powder, comprising: forming a suspension dispersed in a suspension; forming a spherical gel from the suspension; and firing the spherical gel. 2. A negative electrode active material for a non-aqueous secondary battery, comprising a tin oxide powder obtained by the production method according to claim 1. 3. A negative electrode obtained by bonding the negative electrode active material for a non-aqueous electrolyte secondary battery according to claim 2 to a current collector, and a positive electrode active material comprising a material capable of inserting and extracting lithium ions. A non-aqueous electrolyte secondary battery characterized in that a positive electrode formed by bonding a positive electrode to a current collector is housed in a battery container together with a non-aqueous electrolyte through a separator.