JPH11260367A - Active material for secondary battery negative electrode and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To exhibit high capacity in a Li charging/discharging time by including carbon, sulfur, and at least one kind of element from among Ag, Zn, Cd, Al, Ga, In, Tl, Si, Ce, Sn, Pb, As, Sb, and Bi. SOLUTION: Carbon serves as a conductive pass to prevent metal or its sulfide from being isolated electrically, as a cushioning material to absorb expansion/shrinkage of the metal or its sulfide, and as a barrier to prevent the metal or its sulfide from being brought into direct contact with an electrolyte. For effective functioning of carbon as an expansion/shrinkage cushioning material, a metallic phase or a metal sulfide phase of a predetermined size is required. For the size, 1μm or more of the phase concentration is preferably one or less on the average in the observation (12×9 square μm) using electron microscope. A metallic element which forms a complex with carbon and sulfur, and forms alloy with Li and discharging Li at a lower potential is desirable as the element, and fourteen kinds of elements such as Ag are available.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an active material for a negative electrode of a secondary battery and a method for producing the same. More specifically, small,
The present invention relates to an active material for a negative electrode of a secondary battery suitable for a non-aqueous secondary battery such as a lithium secondary battery used as a power source of a lightweight electric device or an electric vehicle, and a method for producing the same.

[0002]

2. Description of the Related Art In recent years, high-capacity secondary batteries have been desired to have higher capacities as electronic devices have become smaller. Therefore, lithium-ion secondary batteries having higher energy density than nickel-cadmium and nickel-metal hydride batteries have been attracting attention. As the negative electrode material, it was first attempted to use lithium metal or an alloy thereof, but during repeated charging and discharging, lithium in the form of dendrite precipitated and penetrated the separator, reached the positive electrode, and was short-circuited. It was found that a fire accident could occur. Furthermore, as a negative electrode material capable of expressing a high capacity, it is known to use a metal that can be doped with lithium and undoped, such as Al, Si, and Sn. There is a problem of a decrease in capacity with respect to charge / discharge cycles.
As a material alternative to these, for example, Japanese Patent No.
The coke-based carbon disclosed in Japanese Patent Application Laid-Open Publication No. H10-19764 is currently in practical use. However, there is a strong demand for an increase in the capacity of a secondary battery, and a negative electrode material having a higher capacity and a secondary battery using the same are required.

[0003]

SUMMARY OF THE INVENTION The object of the present invention is to
It is an object of the present invention to provide a novel negative electrode material capable of exhibiting a higher capacity than conventional coke-based electrode materials when lithium is charged and discharged, a simple production method thereof, and a secondary battery using the negative electrode material.

[0004]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, using a secondary battery negative electrode active material containing carbon, sulfur and a specific element, It has been found that the capacity can be increased, and the present invention has been completed. That is, the present invention relates to carbon and sulfur,
g, Zn, Cd, Al, Ga, In, Tl, Si, C
The present invention relates to a negative electrode active material for a secondary battery, comprising at least one element selected from the group consisting of e, Sn, Pb, As, Sb, and Bi.

[0005]

Next, the details of the present invention will be described. Li
Considering the example of a so-called shuttle type secondary battery that reciprocates between the positive and negative electrodes of an alkali metal ion, the expression of high capacity in the active material of the present invention is mainly caused by a specific metal or its sulfide or sulfur. That is, a specific metal and Li or the like form alloy gold, or Li or the like is occluded in the metal sulfide, or sulfur directly interacts with Li or the like and contributes to the occlusion of Li or the like. With high density
Etc. can be stored. However, when only a specific metal or sulfide is used, as shown in Comparative Example 2 of the present invention,
A stable secondary battery cannot be obtained. This is mainly Li
This is due to the large volume change caused by the occlusion and release of the electrolyte and the decomposition of the electrolyte on the surface of the metal or sulfide. Sulfur dissolves in the electrolyte and does not work as a secondary battery active material. The gist of the present invention is that various problems arising from the change in volume and the decomposition of the electrolytic solution or the decomposition of the active material itself have been overcome by complexing with carbon and its specific structure.

That is, carbon has the following roles. Role as a conductive path to prevent metal or metal sulfide from being electrically isolated, role as cushioning material to absorb expansion and contraction of metal and metal sulfide, and direct contact of metal or sulfide with electrified liquid It is the role of a barrier to prevent. Of course, carbon itself has the ability to absorb and release alkali metals such as Li and contributes to the capacity of the composite active material.

In order for carbon to function effectively as a cushion material for expansion and contraction, a metal phase or metal sulfide phase of a specific size is required, and the size of the phase is 1 μm or more when observed with an electron microscope. The degree to which no apparent phase separation can be confirmed on a scale, preferably the degree to which no apparent phase separation can be confirmed on a scale of 0.1 μm or more is preferred. In the present invention, the phase separation is represented by a heterogeneous phase concentration of 1 μm. That is, in determining the concentration of the hetero phase of 1 μm or more in the present invention, ten 10,000-fold SEM photographs (12 × 9 μm square) were taken, and the number of hetero phases other than carbon of 1 μm or more was counted. However, when a different phase other than carbon was applied to the edge of the screen, one was counted.

The smaller the defects in the material, the higher the material strength. In the present invention, it is considered that the smaller the metal particles, the more the carbon can withstand a larger volume change. That is, the lower limit of the metal particle diameter is not important. Various forms of carbon are known, from graphite with well-developed crystals to amorphous carbon, but the form of carbon is not particularly limited without departing from the spirit of the present invention.

Regarding the metal element to be complexed with carbon and sulfur, an element which forms an alloy with Li is desirable from the viewpoint of capacity improvement, and Li is produced at a potential lower than the oxidation-reduction potential of Li from the viewpoint of energy density. Emitting elements are desirable. From the standpoint of synthesizing the material, an element that forms sulfide and does not form carbide is preferable. From a practical viewpoint, an element having low toxicity is desired.

From the above, the metal elements are Ag, Zn, C
d, Al, Ga, In, Tl, Si, Ce, Sn, P
b, As, Sb, and Bi, among which Ag, Z
n, Cd, Al, Ga, In, Tl, Si, Sn, P
b, As, Sb, Bi are preferable, and Ag, Zn, Al,
Ga, In, Tl, Si, Sn, Pb, Sb, and Bi are more preferable, and Ag, Zn, Al, and G are most preferable.
a, Si, Sn, Pb, Sb, and Bi.

The proportion of these metals in the composite is preferably from 1 to 80% by weight, more preferably from 3 to 70% by weight, most preferably from 10 to 60% by weight. Organometallic compounds or organometallic polymers are generally composed of carbon, hydrogen, metal elements, etc., but even if they contain oxygen, nitrogen or halogen, their composition and structure are particularly limited as long as they act as precursors for metal particles. is not. 3,
Compounds having a 4, 5, 6, or 7-membered ring, or having a structure in which a metal element is incorporated therein, are not particularly excluded. As the organometallic compound, a compound containing a metal ion which forms a complex with an organic substance may be used.

The organic metal compound or the organic metal polymer will be described. By using an organometallic compound as a raw material, it can be mixed with pitch, which is an industrially advantageous carbon precursor, directly or at the molecular level via a solvent or the like. In order to disperse the small hetero phase described in the present invention in carbon, mixing at the molecular level at the raw material stage is very important and is the most important item in the production method of the present invention.
In order to control the mixing ratio of carbon, metal and sulfur, it is effective to use a mixture of an organometallic compound as a precursor and a pitch or the like as a carbon precursor. However, the organometallic compound or the organometallic polymer has a mixture of carbon, a specific metal and sulfur at the atomic level in its own molecule. Active material can be obtained. Naturally, a plurality of organometallic compounds or organometallic polymers can be used at the same time regardless of whether a mixture with a carbon precursor is used.

The organic metal compound may be a compound containing a metal ion which forms a complex with an organic substance. The organometallic compound or the organometallic polymer of the present invention is generally composed of carbon, hydrogen, sulfur and a metal, but even if it contains oxygen, nitrogen or halogen, its composition and structure are particularly limited as long as it functions as a metal precursor. It is not a thing. 3, 4,
Compounds having a five-, six-, or seven-membered ring or having a structure in which a metal element is incorporated therein are not particularly excluded. As the organometallic compound, a compound containing a metal ion which forms a complex with an organic substance may be used. Suitable organometallic compounds include organometallic compounds represented by the following general formula (1),

[0014]

Embedded image

(Where M is Ag, Zn, Cd, Al, G
a, In, Tl, Si, Ce, Sn, Pb, As, S
b, at least one metal element selected from Bi,
X¹, X^Two, X ^Three, X^FourAre each independently a hydrogen atom, (preferred
Or an optionally branched alkyl having 1 to 6 carbon atoms
Group, aryl group (preferably having 1 to 3 rings) or halo
More preferably, an organic metal represented by the following general formula (2)
And the like.

[0016]

Embedded image

(Wherein X ¹ , X ² , X ³ and X ⁴ are each independently a hydrogen atom, an alkyl group (preferably having 1 to 6 carbon atoms) which may have a branch, preferably a ring X ¹ , X ² , X ³ , and X ⁴ are C2 to C4 from the industrial viewpoint.
And an alkyl group or a phenyl group. For a compound having a relatively low boiling point, depending on the size of the molecule, the use of a large side chain reduces transpiration during calcination and may improve the yield. Further, when it is desired to increase the generation of carbon from the organometallic compound, an aromatic residue such as a phenyl group is preferred.

In the organometallic polymer, the metal element may be in the main chain or in the side chain, and the position is not particularly limited. Further, the structure is particularly limited as long as it is a polymer containing a specific metal element, such as a copolymer of an organic metal unit containing a metal element and sulfur and an organic unit containing no metal, or a block copolymer. is not. Further, polymers or compounds containing a plurality of types of metals in the same molecule are not particularly excluded. Particularly preferred are sulfur-containing organotin polymers, and more specifically, poly (dialkyltin sulfide) such as poly (dibutyltin sulfide).

The carbon precursor means an organic substance which is substantially changed into carbon by heat treatment. In particular, the pitches include coal tar pitches from soft pitches to hard pitches in which carbonization proceeds in a liquid phase, and dry distilled liquefied oils. Heavy oils such as coal-based heavy oils, direct-current heavy oils such as residual oil under normal pressure and reduced pressure, and heavy oils such as cracked heavy oils such as ethylene tar by-produced during thermal cracking of crude oil and naphtha Oils or those obtained by solidifying oil or the above through distillation, solvent extraction, or the like at a temperature below which carbonization proceeds. Further, aromatic hydrocarbons such as acenaphthylene, decacyclene, and anthracene; nitrogen-containing cyclic compounds such as phenazine and acridine; sulfur-containing cyclic compounds such as thiophene; and alicyclic rings such as adamantane, which require a pressure of 30 MPa or more, are required. Alternatively, polyphenylene such as biphenyl and terphenyl, which pass through a liquid phase in the process of carbonization, polyvinyl esters such as polyvinyl chloride, polyvinyl acetate and polyvinyl butyral, and polyvinyl alcohol may be mentioned. In particular, in order to obtain a better mixture of carbonaceous materials or a better adhesion between carbonaceous materials and a substance that can electrochemically occlude and release lithium ions by heat treatment in a reducing atmosphere, polychlorinated thermoplastic resins are used. Vinyl is preferred. Further, the organic substances and polymers listed above may be obtained by adding an appropriate amount of acids such as phosphoric acid, boric acid and hydrochloric acid and alkalis such as sodium hydroxide. The thermosetting resin is a resin that solidifies when heated, such as a resol-type or novolak-type phenol resin or a furan resin.

The firing is preferably performed in a non-oxidizing atmosphere. The calcination drives out other than the metal and carbon atoms from the organometallic compound or the organometallic polymer, and at the same time, converts the carbon precursor to carbon. However, it is possible to set an appropriate oxidizing atmosphere in order to control the porosity of the carbonaceous material. Generally, an argon or nitrogen atmosphere or reduced pressure is used. The firing temperature is preferably from 500 to 2000C, more preferably from 700 to 1500C. If the temperature is too low, excluding metals and carbon atoms from the organometallic compound or organometallic polymer results in insufficient conversion of carbon precursor to carbon, which is not preferable. Conversely, if the firing temperature is too high, the metal element is lost due to evaporation, which is not appropriate. The active material obtained by firing in a non-oxidizing atmosphere is crushed or crushed as necessary.

Next, a method for producing a battery electrode using the secondary battery negative electrode active material of the present invention will be described, but the method is not particularly limited by the following description. A binder, a solvent, and the like are added to the secondary battery negative electrode active material of the present invention,
The slurry is applied to a metal current collector substrate such as a copper foil, and the slurry is applied and dried to form an electrode. Further, the electrode material can be directly formed into an electrode shape by a method such as roll molding or compression molding. When the active material of the present invention is used as an electrode, it can be generally used as particles of 0.1 to 50 μm.

Examples of the binder that can be used for the above purpose include:
Solvent-stable, polyethylene, polypropylene,
Polyethylene terephthalate, aromatic polyamide, resin-based polymers such as cellulose, styrene-butadiene rubber,
Rubber-like polymers such as isoprene rubber, butadiene rubber, and ethylene / propylene rubber, styrene / butadiene / styrene block copolymers, hydrogenated products thereof, styrene / ethylene / butadiene / styrene copolymers, styrene / isoprene / styrene block copolymers Polymers, thermoplastic elastomeric polymers such as hydrogenated products thereof, syndiotactic 1,2-polybutadiene, ethylene / vinyl acetate copolymer, propylene / α-olefin (2 to 12 carbon atoms)
Soft resinous polymers such as copolymers, fluorine-based polymers such as polyvinylidene fluoride, polytetrafluoroethylene, polytetrafluoroethylene / ethylene copolymers, and alkali metal ions, particularly lithium ions Molecular compositions.

Examples of the polymers having ion conductivity include polyether polymer compounds such as polyethylene oxide and polypropylene oxide, crosslinked polymers of polyether compounds, polyepichlorohydrin, polyphosphazene, polysiloxane, polyvinylpyrrolidone, and the like. Polyvinylidene carbonate, a polymer compound such as polyacrylonitrile, a lithium salt, or a system in which an alkali metal salt mainly composed of lithium is compounded, or propylene carbonate, ethylene carbonate, having a high dielectric constant such as γ-butyrolactone A system containing an organic compound can be used.

The mixing form of the active material and the binder can take various forms. That is, a form in which both particles are mixed, a form in which a fibrous binder is mixed in such a manner as to be entangled with the electrode particles, and a form in which a layer of the binder is attached to the particle surface are exemplified. The mixing ratio of the electrode powder and the binder is preferably 0.1 to 30% by weight, more preferably 0.5 to 10% by weight, based on the active material. If the binder is added in an amount larger than this, the internal resistance of the electrode increases, which is not preferable. If the amount is smaller than this, the binding property between the current collector and the active material is poor.

Hereinafter, the structure of a non-aqueous secondary battery when the active material of the present invention is used as a negative electrode active material will be described in detail. However, the present invention is not limited to the following without departing from the gist thereof. Absent. The secondary battery of the present invention can be manufactured by combining the above-mentioned negative electrode material with any positive electrode material, electrolytic solution and separator.

As a positive electrode material, conventionally known
A shift can also be used and is not particularly limited. concrete
Has LiFeO_Two, LiCoO_Two, LiNiO_Two, Li
Mn_TwoO_FourAnd their non-stoichiometric compounds, MnO_Two, Ti
S_Two, FeS_Two, Nb_ThreeS_Four, Mo _ThreeS_Four, CoS_Two, V
_TwoO_Five, P_TwoO_Five, CrO_Three, V_ThreeO_Three, TeO_Two, GeO_Two
Etc. can be used.

The electrolyte is not particularly limited as long as the electrolyte is dissolved in an organic solvent, and any conventionally known electrolyte can be used. As the organic solvent, propylene carbonate, ethylene carbonate, esters such as γ-butyl lactone, diethyl ether, tetrahydrofuran, substituted tetrahydrofuran, dioxolan, pyran and derivatives thereof, dimethoxyethane, ethers such as diethoxyethane, and 3-methyl- Examples include 3-substituted-2-oxazolidinones such as 2-oxazolidinone, sulfolane, methylsphorane, acetonitrile, propionitr and the like, and these are used alone or as a mixture of two or more. Further, as the electrolyte, lithium perchlorate, lithium borofluoride, lithium phosphofluoride, lithium aluminate, lithium halide, lithium trifluoromethanesulfonate, or the like can be used.

The separator holding the electrolyte is generally a material having excellent liquid retention properties. For example, the separator is impregnated with a non-woven fabric or a porous film of a polyolefin resin. As the configuration of the battery, a structure in which a belt-like positive electrode and a negative electrode are spirally formed with a separator interposed therebetween, a structure in which the positive electrode and the negative electrode are stacked with a separator interposed therebetween, and the like are employed.

[0029]

EXAMPLES The present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. As the carbon precursor, a coal tar pitch having a softening point of 98 ° C., a toluene insoluble content of 40%, and a quinoline insoluble content of 0% was used. The calcination is performed in an Ar gas stream, and the heating rate is 1.6.
The temperature was kept at 1000 ° C. for 2 hours at 5 ° C./min. The obtained fired product was pulverized to an average particle size of 20 μm or less to obtain a sample.
The amount of metal contained in the obtained metal-carbon composite material is Pe
It was determined as a residual from C, H, and N measured with an rkin Elmer 2400 CHN meter.

The measurement of the particle diameter of the metal fine particles in the composite material and the observation of the structure were performed by a scanning electron microscope (SEM) as follows. Each sample was coated and rolled on a copper electrode plate. Each copper electrode plate was cut into strips of about 1 mm width, epoxy resin was added and impregnated while vacuum degassing was performed, followed by curing at room temperature for 5 hours. Further, the structure was cured at 80 ° C. for 8 hours to fix the structure. The epoxy resin used here was compounded by (a) p-aminophenol type trifunctional epoxy (trade name: ELM100) manufactured by Sumitomo Chemical Co., Ltd., and (b) 1-benzyl-2-methyl manufactured by Shikoku Chemicals Co., Ltd. Imidazole (abbreviation 1B2MZ) and (c) reagent isophoronediamine (abbreviation IPD) were each composed by weight composition (a) :( b) :( c) = 10
The mixture was mixed at 0: 1: 40.

A cross section of the sample in the cured product obtained as described above was cut out with various blades, and an ultra-thin section to be subjected to transmission electron microscope observation with a commercially available diamond knife using an ultramicrotome apparatus was sampled from the cross section of the sample. . At the same time, the cut surfaces of the remaining samples from which the ultrathin sections had been collected were subjected to scanning electron microscope observation. In scanning electron microscope observation, a vapor deposition film of about 100 ° was applied to the sample by a carbon vacuum vapor deposition device to prevent charge-up, and a field emission type device (JS manufactured by JEOL Ltd.) was used.
M-6300F) and the observation was performed with the acceleration voltage set to 5 kV. The particle size was measured by observing the reflected electron image and confirming the Sn-containing particles, obtaining a secondary electron image photograph in the same field of view, and measuring the particles confirmed by the reflected electron image from the secondary electron image photograph. .

In determining the concentration of the heterophase of 1 μm or more, ten 10,000-fold SEM photographs (12 × 9 μm square) were taken, and the number of heterophases other than carbon of 1 μm or more was counted. When a different phase other than carbon hit the edge of the screen, one was counted.
In scanning electron microscope observation, a vapor deposition film of about 100 ° was applied to the sample using a carbon vacuum vapor deposition device to prevent charge-up, and the sample was introduced into a field emission type device (JSM-6300F manufactured by JEOL Ltd.). The observation was performed with the acceleration voltage set to 5 kV. The particle size was measured by observing the reflected electron image and confirming the Sn-containing particles, obtaining a secondary electron image photograph in the same field of view, and measuring the particles confirmed by the reflected electron image from the secondary electron image photograph. .

Observation with a transmission electron microscope was carried out to determine the particle size of particles having a small particle size that could not be confirmed because the resolution was insufficient with a scanning electron microscope. The device used was JEM-2010 manufactured by JEOL Ltd. The acceleration voltage was set to 200 kV, the ultrathin section was introduced into the apparatus, and observed at a magnification of 10,000 to 500,000. The particle size was measured by observing a high-magnification image of the fine particles and observing lattice fringes to confirm that it was a crystalline object. The particles were photographed at a magnification of about 200,000, and measured from an enlarged photograph. The fine particles measured by such a method are evidence that they are only Sn-containing particles as crystals, but since the carbonaceous component is known to be amorphous based on the result of X-ray diffraction measurement, and / or Considering that there is no possibility of the presence of other crystalline components from the composition and / or that the presence of crystalline impurities containing no Sn is not recognized by analysis by a chemical method, such crystal grains are converted into Sn particles.
The method of measuring the particle size assuming that the particles are contained does not impair the accuracy of the method for measuring the particle size as the object of the present invention.

The product was identified by the X-ray diffraction method as follows. JEOL X-ray diffractometer (JDX-3
500), using a target: Cu (Kα ray) graphite monochromator, output: 40 kV 200
mA, step scan: step angle 0.02 °, counting time: 1 sec, divergence slit (DS): 1/2 °,
Receiving slit (RD): 0.2 mm, scattering slit (S
S): 1/2 °, measurement range: 3 ° ≦ 2θ ≦ 90 °, sample plate: 0.2 mm thick glass sample plate.

The evaluation of a non-aqueous secondary battery as a negative electrode material is as follows.
The measurement was performed by a bipolar method using a half cell in which the counter electrode was Li.
As the non-aqueous electrolyte, a solution obtained by dissolving 1 mol / L of lithium perchlorate in a 1: 1 solution of ethylene carbonate (EC) and diethyl carbonate (DEC) was used. For the evaluation electrode, a sample pulverized to 45 μm or less was
It was prepared by applying it to a copper foil with VDF. The charge current density for doping Li was 0.16 mA / cm ² , and the discharge current density for dedoping Li was 0.32 mA / cm ² . Dedoping was performed up to +1.5 V with respect to the oxidation-reduction potential of Li.

Example 1 Di (di-n-butyltin sulfide) having a molecular weight in terms of styrene of 570 determined by GPC
(Manufactured by Asmax Corporation) was used. The above pitch 5g is converted to 6
1.96 g of the organotin compound was added to a solution of the organotin compound in 60 ml of tetrahydrofuran (THF) at 0 ° C., and the mixture was stirred at room temperature for 12 hours. THF was removed by distillation under reduced pressure to remove the mixture of the organotin compound and the carbon precursor. Obtained. The mixture was fired in a stream of Ar using a tubular electric furnace. Table 1 shows the discharge capacity determined during the first Li de-doping process, the metal element concentration, and 1 μm.
The names of the compounds determined by the above heterophasic concentration and X-ray diffraction are shown.

Example 2 Using the same organotin polymer as in Example 2, the above-mentioned pitch of 3 g was added at 60 ° C. in THF of 40 m.
Then, 4.00 g of the organotin compound was added to the solution dissolved in 1 and the mixture was stirred at room temperature for 12 hours, and then THF was removed by distillation under reduced pressure to obtain a mixture of the organotin compound and a carbon precursor. The mixture was fired in a stream of Ar using a tubular electric furnace. Table 1 shows the first L
The discharge capacity determined in the dedoping process of i, the concentration of the metal element, the concentration of the hetero phase of 1 μm or more, and the compound name determined by X-ray diffraction are shown.

Comparative Example 1 A pitch used as a carbon precursor was obtained by sintering at 1000 ° C. by the above method alone. Table 1 shows the discharge capacity determined in the first Li de-doping process.

Comparative Example 2 Tin particles having a particle size of 20 μm purchased from Aldrich were used directly as an active material. In the evaluation as a negative electrode material of a non-aqueous secondary battery, the potential fluctuated during the first Li doping process, and a stable result was not obtained. A charging current corresponding to 900 mAh / g or more flowed, but was not discharged.

Comparative Example 3 An active material was prepared by mixing tin particles of 75 μm purchased from Aldrich and carbon described in Comparative Example 1 having an average particle diameter of about 20 μm in a weight ratio of 5: 5. Mixing was performed for 8 hours using a V-type blender.
The charging current corresponding to 450 mAh / g or more flowed, but was not discharged. In Examples 1 and 2, tin and L
Assuming that i made the alloy and the capacity of tin was 900 mAh / g, the tin concentration calculated from the discharge capacity was 19.8 and 26.0 wt%, respectively, which was higher than the measured tin concentration. This indicates that in addition to tin metal and carbon, tin sulfide or sulfur was involved in the occlusion and release of Li. However, the value of Comparative Example 1 was used for the capacity of carbon.

[0041]

Table 1 Discharge capacity Sn concentration Heterophase concentration Compound mAh / g wt% X-ray diffraction Example 1 346 11 0.7 C, Sn, SnS Example 2 389 23 0.2 C, Sn, SnS Comparative example 1 209 0 C Comparative Example 2 0 100 Sn Comparative Example 3 0 50 C, Sn

[0042]

According to the present invention, it has become possible to obtain a negative electrode material capable of exhibiting a higher capacity than conventional coke-based electrode materials.

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tetsutsu Nishiwaki 3-1, Chuo, Ami-cho, Inashiki-gun, Ibaraki Pref.

Claims (12)

[Claims] 1. Carbon and sulfur, Ag, Zn, Cd, A
1, Ga, In, Tl, Si, Ce, Sn, Pb, A
An active material for a negative electrode of a secondary battery, comprising at least one element selected from s, Sb, and Bi. 2. Observation using an electron microscope (12 × 9 μm
Ag), Zn, Cd, Al, Ga, I
n, Tl, Si, Ce, Sn, Pb, As, Sb, Bi
2. The active material for a negative electrode of a secondary battery according to claim 1, wherein the concentration of at least one element selected from the group consisting of at least 1 μm in different phases is 1 or less on average. 3. A non-aqueous secondary battery comprising the active material for a negative electrode of a secondary battery according to claim 1. 4. At least carbon and sulfur and Ag, Zn,
Cd, Al, Ga, In, Tl, Si, Ce, Sn, P
3. The method for producing a negative electrode active material for a secondary battery according to claim 1, wherein an organometallic compound containing at least one element selected from b, As, Sb, and Bi is calcined. 5. The method for producing a negative electrode active material for a secondary battery according to claim 4, wherein a carbon precursor is added during firing. 6. The method for producing a negative electrode active material for a secondary battery according to claim 5, wherein the carbon precursor is a pitch or a thermosetting resin. 7. An organic metal compound represented by the following general formula (1):
It is an organometallic compound shown, Claims characterized by the above-mentioned.
5. The method for producing a negative electrode active material for a secondary battery according to 4. Embedded image(Where M is Ag, Zn, Cd, Al, Ga, In, T
1, Si, Ce, Sn, Pb, As, Sb, Bi
At least one metal element, X¹, X^Two, X ^Three, X^Four
Are each independently a hydrogen atom or an optionally branched alkyl
Group, aryl group or halogen atom) 8. An organometallic compound having at least a main chain,
Ag, Zn, Cd, Al, Ga, In, Tl, Si, C
The method according to claim 4, wherein an organometallic polymer containing at least one element selected from the group consisting of e, Sn, Pb, As, Sb, and Bi and a sulfur element is used. 9. The method for producing a negative electrode active material for a secondary battery according to claim 4, wherein the organometallic compound is an organometallic compound represented by the following general formula (2). Embedded image (Wherein X ¹ , X ² , X ³ and X ⁴ are each independently a hydrogen atom,
Represents an alkyl group, an aryl group or a halogen atom which may have a branch) 10. The method for producing a negative electrode active material for a secondary battery according to claim 9, wherein M in the general formula (2) is Sn. 11. The method according to claim 8, wherein the organometallic polymer containing a sulfur element is an organotin polymer. 12. The method according to claim 11, wherein the organotin polymer is poly (dialkyltin sulfide).