JP2016154122A - Negative electrode active material for nonaqueous electrolyte secondary battery, negative electrode, and nonaqueous electrolyte secondary battery - Google Patents

Abstract

The present invention provides a negative electrode active material for a non-aqueous electrolyte secondary battery, a negative electrode including the same, and a non-aqueous electrolyte secondary battery having the same, which have a higher capacity than conventional ones. Objective. The substance A includes a lithium compound contained in the substance A, and the substance A includes a carbon material, a metal, a metalloid, an alloy, an oxide, and the like that can electrochemically occlude and release lithium ions. Including at least one selected from the group consisting of nitrides, the lithium compound consists of Li2CO3, LiOH, Li2O, LiF, ROLi, and ROCO2Li (R represents CnH2n + 1 (n is an integer of 1 or more)). A negative electrode active material for a non-aqueous electrolyte secondary battery, which is at least one selected from the group, and the ratio of the lithium compound to the substance A is 10 mass ppm or more and 1000 mass ppm or less. [Selection figure] None

Description

  The present invention relates to a negative electrode active material for a non-aqueous electrolyte secondary battery, a negative electrode including the same, and a non-aqueous electrolyte secondary battery having the same.

  With the recent development of electronic technology and increasing interest in environmental technology, various electrochemical devices have been developed. In particular, since there are many requests for energy saving, expectations for electrochemical devices that can contribute to energy saving are increasing. Examples of such electrochemical devices include power storage devices such as non-aqueous electrolyte secondary batteries.

  Lithium ion secondary batteries, which are also representative examples of nonaqueous electrolyte secondary batteries, have been used mainly as rechargeable batteries for portable devices, but in recent years, they are also expected to be used as batteries for hybrid and electric vehicles. . When a lithium ion secondary battery is used in an automobile, a higher capacity is required as compared with a case where it is used for a portable device as in the past.

Patent Document 1 discloses a technique for preventing deterioration of battery characteristics after high-temperature storage by adding LiF to a carbonaceous material in a negative electrode plate using a chargeable / dischargeable carbonaceous material as an active material. .
Patent Document 2 discloses that at least one of the positive electrode and the negative electrode is A (COOLi) _n (where A is H or an organic substance containing C and H, and n is 1 ≦ n. A technique for improving the charge / discharge cycle characteristics of a battery is disclosed.

Japanese Patent Laid-Open No. 11-162520 Japanese Patent Laid-Open No. 11-265719

  However, Patent Document 1 and Patent Document 2 do not describe a non-aqueous electrolyte secondary battery having a high capacity. Therefore, the conventional non-aqueous electrolyte secondary battery still has room for improvement.

  Accordingly, an object of the present invention is to provide a negative electrode active material for a nonaqueous electrolyte secondary battery, a negative electrode including the same, and a nonaqueous electrolyte secondary battery having the same, which has a higher capacity than conventional ones. And

  As a result of intensive studies to solve the above problems, the inventors of the present invention electrochemically include lithium ions containing at least one specific lithium compound as a negative electrode active material used in a non-aqueous electrolyte secondary battery. A substance A containing at least one selected from the group consisting of carbon materials, metals, metalloids, alloys, oxides, and nitrides capable of occluding and releasing oxygen, wherein the ratio of lithium compound to substance A is It has been found that the use of a material having a mass of 10 mass ppm or more and 1000 mass ppm or less can solve the above problems, and has completed the present invention.

That is, the present invention is as follows.
[1] At least selected from the group consisting of Li ₂ CO ₃ , LiOH, Li ₂ O, LiF, ROLi, and ROCO ₂ Li (R represents C _n H _{2n + 1} (n represents an integer of 1 or more)). Substance A containing at least one selected from the group consisting of carbon materials, metals, metalloids, alloys, oxides, and nitrides that can electrochemically occlude and release lithium ions, including one lithium compound A negative electrode active material for a non-aqueous electrolyte secondary battery, wherein the ratio of the lithium compound to the substance A is 10 mass ppm or more and 1000 mass ppm or less.

[2] The substance A is a carbon material capable of electrochemically occluding and releasing lithium ions, and the at least one lithium compound is Li ₂ CO ₃ , Li ₂ O, LiF, and ROCO ₂ Li ( The negative electrode active material for nonaqueous electrolyte secondary batteries according to [1], wherein R is selected from the group consisting of C _n H _{2n + 1} (n represents an integer of 1 or more).

[3] A negative electrode comprising the negative electrode active material for a nonaqueous electrolyte secondary battery according to [1] or [2].

[4] A nonaqueous electrolyte secondary battery comprising the negative electrode according to [3].

  The nonaqueous electrolyte secondary battery having a negative electrode including the negative electrode active material for a nonaqueous electrolyte secondary battery of the present invention has a higher capacity than that of the conventional one.

  Hereinafter, a mode for carrying out the present invention (hereinafter also referred to as “the present embodiment”) will be described in detail. The following embodiments are examples for explaining the present invention, and are not intended to limit the present invention to the following contents. The present invention can be implemented with appropriate modifications within the scope of the gist.

(Negative electrode active material)
The negative electrode active material according to this embodiment is used for a non-aqueous electrolyte secondary battery.
The negative electrode active material includes a material A described later and a lithium compound described later contained in the material A, and the material A is a carbon material, metal, metalloid, alloy capable of electrochemically inserting and extracting lithium ions. And at least one selected from the group consisting of oxides and nitrides, the lithium compound may be Li ₂ CO ₃ , LiOH, Li ₂ O, LiF, ROLi, and ROCO ₂ Li (R is C _n H _{2n +1} (represents n is an integer of 1 or more)). The ratio of the lithium compound to the substance A is 10 mass ppm or more and 1000 mass ppm or less.

-Substance A-
The carbon material capable of electrochemically occluding and releasing lithium ions that can be contained in the substance A may be a conventionally known carbon material such as hard carbon, soft carbon, artificial graphite, natural graphite, graphite, pyrolytic carbon, Examples include coke, glassy carbon, a fired body of an organic polymer compound, mesocarbon microbeads, carbon fiber, activated carbon, graphite, carbon colloid, and carbon black.
In particular, the coke may be a conventionally known one, and examples thereof include pitch coke, needle coke, and petroleum coke. In addition, the fired body of the organic polymer compound is obtained by firing and polymerizing a polymer material such as a phenol resin or a furan resin at an appropriate temperature.
These may be used alone or in combination of two or more.

The metal or semimetal that can be contained in the substance A may be a conventionally known metal.
Examples of metal elements and metalloid elements include magnesium (Mg), calcium (Ca), aluminum (Al), titanium (Ti), zinc (Zn), silver (Ag), hafnium (Hf), and zirconium (Zr). Yttrium (Y), Tin (Sn), Lead (Pb), Indium (In), Silicon (Si), Antimony (Sb), Bismuth (Bi), Gallium (Ga), Germanium (Ge), Arsenic (As) Etc. Among these, the metal elements and metalloid elements of Group 4 or 14 in the long-period periodic table are preferable, and titanium (Ti), tin (Sn), and silicon (Si) are particularly preferable.
These may be used alone or in combination of two or more.

The alloy that can be included in the substance A includes an alloy including one or more metal elements and one or more metalloid elements in addition to an alloy including two or more metal elements (described above). Further, the alloy may have a nonmetallic element as long as it has metal properties as a whole.
In the structure of the alloy, a solid solution, a eutectic (eutectic mixture), an intermetallic compound, or two or more of these coexist.

The oxide that can be contained in the substance A may be a conventionally known oxide. For example, cobalt oxide, nickel oxide, iron oxide, silicon oxide, niobium pentoxide, tungsten oxide, molybdenum oxide, titanium dioxide, lithium titanate (for example, , Li ₄ Ti ₅ O ₁₂ etc.).
These may be used alone or in combination of two or more.

The nitride that can be contained in the substance A may be a conventionally known nitride, and examples thereof include those represented by the general formula: Li _3-x M _x N (M = Co, Ni, Mn).
These may be used alone or in combination of two or more.

  These carbon materials, metalloids, metals, alloys, oxides, and nitrides may be used alone or in combination of two or more.

  The substance A is preferably a carbon material that can electrochemically occlude and release lithium ions.

-Lithium compound-
The lithium compound contained in the substance A is composed of Li ₂ CO ₃ , LiOH, Li ₂ O, LiF, ROLi, and ROCO ₂ Li (R represents C _n H _{2n + 1} (n represents an integer of 1 or more)). At least one selected from the group. Among these, the lithium compound is selected from the group consisting of Li ₂ CO ₃ , Li ₂ O, LiF, and ROCO ₂ Li (R represents C _n H _{2n + 1} (n represents an integer of 1 or more)). It is preferably at least one, and at least one selected from the group consisting of Li ₂ CO ₃ , LiF, and ROCO ₂ Li (R represents C _n H _{2n + 1} (n is an integer of 1 or more)). More preferably.
N is preferably 1 or more, and preferably 5 or less.
These may be used alone or in combination of two or more.

The ratio of the lithium compound to the substance A (the amount of the lithium compound contained in the substance A) is 10 mass ppm or more, preferably 20 mass ppm or more, preferably 50 mass ppm or more with respect to the mass of the substance A. More preferably, it is 1000 ppm by mass or less, preferably 500 ppm by mass or less, and more preferably 450 ppm by mass or less.
When the ratio of the lithium compound to the substance A is within the above range, a higher capacity can be obtained.

  The ratio of the lithium compound to the substance A can be measured by a conventionally known method. For example, calculation of the mixing ratio of the substance A and the lithium compound, high frequency inductively coupled plasma emission spectroscopy (ICP-AES analysis), X-ray It can be measured and calculated by photoelectron spectroscopic analysis (XPS analysis), Fourier transform infrared spectroscopic analysis (FT-IR analysis), Raman spectroscopic analysis and the like.

  The method of incorporating the lithium compound into the substance A may be a conventionally known method. For example, the lithium compound may be mixed with the substance A at the time of producing the negative electrode, and the lithium compound may be added to the surface of the substance A during the production of the negative electrode active material. It may be contained in at least a part by utilizing a chemical reaction, a lithium compound may be attached to at least a part of the substance A in the battery at the time of charge / discharge, or a combination thereof may be performed.

((Negative electrode))
The negative electrode according to the present embodiment includes the negative electrode active material for a nonaqueous electrolyte secondary battery according to the present embodiment described above.
And it is preferable that the negative electrode which concerns on this embodiment contains a electrically conductive material, a collector, and a binder (binder) other than the said negative electrode active material for nonaqueous electrolyte secondary batteries.

(Conductive material)
The conductive material that can be included in the negative electrode is not particularly limited, and may be a known material that can conduct electrons. As the conductive material, for example, non-graphitic carbonaceous materials such as graphite and carbon black (including acetylene black) and various cokes are preferable. These may be used alone or in combination of two or more.

(Current collector)
The current collector that can be included in the negative electrode is not particularly limited, and examples thereof include metal foils such as copper, nickel, and stainless steel, expanded metal, punch metal, foam metal, carbon cloth, and carbon paper.
These may be used alone or in combination of two or more.

(Binder (binder))
Known binders (binders) that can be included in the negative electrode can bind at least two selected from the group consisting of the negative electrode active material for non-aqueous electrolyte secondary batteries, the conductive material, and the current collector. Good.
Such a binder (binder) is not particularly limited, and for example, carboxymethyl cellulose, styrene-butadiene crosslinked rubber latex, acrylic latex, and polyvinylidene fluoride are preferable. These may be used alone or in combination of two or more.
The solvent that dissolves the binder (binder) is not particularly limited and may be any known solvent as long as it is a solvent that dissolves the binder (binder). Among these, water and N-methyl-2-pyrrolidone are preferable as the solvent. These may be used alone or in combination of two or more.

(((Nonaqueous electrolyte secondary battery)))
The nonaqueous electrolyte secondary battery according to the present embodiment includes the negative electrode according to the present embodiment described above.
And the nonaqueous electrolyte secondary battery which concerns on this embodiment may have a positive electrode, a nonaqueous electrolyte, a separator, an exterior body, etc. other than the said negative electrode. Such a nonaqueous electrolyte secondary battery has excellent capacity performance.

((Positive electrode))
The positive electrode used in the non-aqueous electrolyte secondary battery according to the present embodiment preferably includes a positive electrode active material, a conductive material, a current collector, and a binder (binder).

(Positive electrode active material)
The positive electrode active material that can be included in the positive electrode is not particularly limited as long as it can electrochemically occlude and release lithium ions, and may be a known material.
In particular, the positive electrode active material is preferably a material containing lithium.
Such a positive electrode active material is not particularly limited.
Following formula (1):
_{Li x Ni 1-y M y} O z ··· (1)
(In the formula, M represents at least one element selected from the group consisting of transition metal elements, and 0 <x ≦ 1.3, 0 ≦ y <1, 1.8 <z <2.2. .)
An oxide represented by
Following formula (2):
_{Li x M y O z ··· (} 2)
(In the formula, M represents at least one element selected from the group consisting of transition metal elements, and 0 <x ≦ 1.3, 0.8 <y <1.2, 1.8 <z <2 .2)
A layered oxide represented by
Following formula (3):
_{Li x Mn 2-y M y} O z ··· (3)
(In the formula, M represents at least one element selected from the group consisting of transition metal elements, and 0 <x ≦ 1.3, 0.2 <y <0.8, 3.5 <z <4. .5.)
An oxide represented by
Following formula (4):
_{LiMn 2-x Ma x O 4} ··· (4)
(In the formula, Ma represents at least one element selected from the group consisting of transition metal elements, and 0.2 ≦ x ≦ 0.7.)
A spinel oxide represented by
Following formula (5-1):
Li ₂ McO ₃ (5-1)
(In the formula, Mc represents at least one element selected from the group consisting of transition metal elements.)
An oxide represented by
Following formula (5-2):
LiMdO ₂ (5-2)
(In the formula, Md represents at least one element selected from the group consisting of transition metal elements.)
A composite oxide with an oxide represented by the following formula (5-3):
_{zLi 2 McO 3 - (1-} z) LiMdO 2 ··· (5-3)
(In formula (5-3), Mc and Md have the same meanings as in formulas (5-1) and (5-2), respectively, and 0.1 ≦ z ≦ 0.9.)
Li-excess layered oxide positive electrode active material represented by
Following formula (6):
LiMb _1-y Fe _y PO ₄ (6)
(In the formula, Mb represents at least one element selected from the group consisting of Mn and Co, and 0 ≦ y ≦ 1.0.)
An olivine-type positive electrode active material represented by
Following formula (7):
Li ₂ MePO ₄ F (7)
(In the formula, Me represents at least one element selected from the group consisting of transition metal elements.)
The compound represented by these is mentioned.

  These may be used alone or in combination of two or more.

(Conductive material)
The conductive material that can be included in the positive electrode is not particularly limited, and may be a known material that can conduct electrons. As the conductive material, for example, activated carbon, various cokes, non-graphitic carbonaceous materials such as carbon black and acetylene black, graphite (graphite), and metal powders such as aluminum, titanium, and stainless steel are preferable. These may be used alone or in combination of two or more.

(Current collector)
The current collector that can be included in the positive electrode is not particularly limited, and examples thereof include metal foils such as aluminum, titanium, and stainless steel, expanded metal, punch metal, foam metal, carbon cloth, and carbon paper. These may be used alone or in combination of two or more.

(Binder (binder))
The binder (binder) that can be included in the positive electrode may be a known material that can bind at least two selected from the group consisting of the positive electrode active material, the conductive material, and the current collector.
As such a binder (binder), for example, polyvinylidene fluoride and fluororubber are preferable. These may be used alone or in combination of two or more.
The solvent that dissolves the binder (binder) is not particularly limited and may be any known solvent as long as it is a solvent that dissolves the binder (binder). Among these, N-methyl-2-pyrrolidone, ethyl acetate, and ethyl cellosolve are preferable as the solvent. These may be used alone or in combination of two or more.

((Nonaqueous electrolyte))
The nonaqueous electrolyte in the present embodiment may be a liquid electrolyte or a solid electrolyte. Examples of the liquid electrolyte include a non-aqueous electrolyte solution obtained by dissolving an electrolyte (salt) in a non-aqueous solvent. Examples of the solid electrolyte include those obtained by dispersing an electrolyte (salt) in a polymer, and polymers. The thing impregnated with the said non-aqueous electrolyte is mentioned.

(Electrolyte (salt))
The electrolyte (salt) used in the nonaqueous electrolyte secondary battery according to this embodiment is not particularly limited and may be a conventionally known one.
The electrolyte is preferably a lithium salt. For example, LiPF ₆ (lithium hexafluorophosphate), LiClO ₄ , LiAsF ₆ , Li ₂ SiF ₆ , LiOSO ₂ C _k F _{2k + 1} [k is an integer of 1 to 8] LiN (SO ₂ C _k F _{2k + 1} ) ₂ [k is an integer of 1 to 8], LiPF _n (C _k F _{2k + 1} ) _6-n [n is an integer of 1 to 5, k is 1 to 8 Integer], LiCF ₃ SO ₃ , LiC ₄ F ₉ SO ₃ , Li (CF ₃ SO ₂ ) ₃ C, LiAlO ₄ , LiAlCl ₄ , LiBF ₄ , LiBF _q (C _s F _{2s + 1} ) _4-q [q Is an integer of 1 to 3, s is an integer of 1 to 8], LiB (C ₆ F ₅ ) ₄ , LiB (C ₂ O ₄ ) ₂ , Li ₂ B ₁₂ F _b H _12-b [b is 0 to 3 _{integer], LiB (C 6 H 5)} 4, LiPF n (C k F 2k + 1) 6-n [n is an integer of 1 to 5, k is an integer of 1 to 8], LiPF ₄ (C ₂ O ₄ ), Li _{BF 2 (C 2 O 4)} , LiB (C 3 O 4 H 2) 2, LiPF 4 (C 2 O 2), LiPF 2 (C 2 O 4) 2 and the like. Among these, LiPF ₆ is preferable from the viewpoint of obtaining excellent capacity performance and excellent cycle characteristics.
These may be used alone or in combination of two or more.

  The electrolyte in the present embodiment may be a liquid electrolyte or a solid electrolyte.

(Non-aqueous solvent)
The nonaqueous solvent used in the nonaqueous electrolyte secondary battery according to this embodiment is not particularly limited and may be a conventionally known one.
The non-aqueous solvent is preferably an aprotic polar solvent, for example, ethylene carbonate, propylene carbonate, 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, 2,3-pentylene. Cyclic carbonates such as carbonate, trifluoromethylethylene carbonate, fluoroethylene carbonate and 4,5-difluoroethylene carbonate; lactones such as γ-butyrolactone and γ-valerolactone; cyclic sulfones such as sulfolane; cyclic ethers such as tetrahydrofuran and dioxane; Ethyl methyl carbonate, dimethyl carbonate, diethyl carbonate, methyl propyl carbonate, methyl isopropyl carbonate, dipropyl carbonate, methyl butyl carbonate Linear carbonates such as acetonitrile, dibutyl carbonate, ethyl propyl carbonate and methyl trifluoroethyl carbonate; nitriles such as acetonitrile; chain ethers such as dimethyl ether; chain carboxylic acid esters such as methyl propionate; chain ethers such as dimethoxyethane A carbonate compound etc. are mentioned.
These may be used alone or in combination of two or more.

((Separator))
The separator used in the non-aqueous electrolyte secondary battery according to the present embodiment is not particularly limited, and may be a conventionally known separator that has high ion permeability and electrically isolates the positive electrode and the negative electrode. Any function may be used.
Examples of the separator include a synthetic resin microporous film, a nonwoven fabric, papermaking, a porous film, a structure thereof, and a solid electrolyte film.
As a synthetic resin microporous film, what consists of polyolefin resin, such as polyethylene and a polypropylene, for example is preferable.
As a nonwoven fabric, papermaking, and a porous film, you may each consist of cellulose, aromatic polyamide, a fluororesin, polyolefin etc., for example.
These non-woven fabrics, papermaking, and porous membranes are composed of a mixture of the aforementioned resin and at least one inorganic material such as alumina or silica, or at least a part of the surface of the aforementioned resin. It may be coated with the inorganic material.

((Exterior body))
The exterior body used for the nonaqueous electrolyte secondary battery according to the present embodiment is not particularly limited and may be a conventionally known one. The material of the exterior body is not particularly limited, and examples thereof include metals such as stainless steel, iron, and aluminum, and laminate films in which the surface of the metal is coated with a resin.

  The nonaqueous electrolyte secondary battery according to the present embodiment may have the same configuration as that conventionally known except for the configuration described above. Examples of the nonaqueous electrolyte secondary battery according to this embodiment include a lithium ion secondary battery and a lithium ion capacitor.

  EXAMPLES Hereinafter, although an Example is given and embodiment of this invention is described, this invention is not limited to these Examples.

  Measurement methods and evaluation methods for various physical properties in Examples and Comparative Examples are shown below.

(Capacity evaluation)
The cylindrical secondary batteries obtained in the following examples and comparative examples were used in a constant temperature bath of 20 ° C. using a charge / discharge device (product name: ACD-01, manufactured by Asuka Electronics Co., Ltd.). After charging for 8 hours at a constant potential of 4.2 V (positive electrode-negative potential) at a constant current of 0.3 C, the battery was discharged until a potential of 3.0 V was reached at a constant current of 0.3 C (charge and discharge at the first cycle ). Note that “1.0 C” refers to a current value at which a fully charged battery can discharge electricity in one hour.
After the first charge / discharge, after charging for 5 hours in a constant temperature and constant voltage system of 0.5C and 4.2V in a constant temperature: 20 ° C constant temperature chamber, the potential is set to 3.0V with a constant current of 0.3C. Discharged until The amount of discharge in the second cycle was taken as the capacity of this battery. The results are shown in Table 1.

  Hereinafter, each example and each comparative example will be described in detail.

[Example 1]
(A) Manufacture of negative electrode 1 kg of natural graphite having an average particle size of 10 μm and 0.8 g of lithium carbonate (Li ₂ CO ₃ ) were mixed by a ball mill using water as a medium, and then in the atmosphere at a temperature of 150 ° C. for 3 hours. Heated to obtain a powder. This powder was used as a negative electrode active material. The amount of the lithium compound contained in the obtained powder was 800 mass ppm when measured and calculated using an XPS analyzer (manufactured by JEOL Ltd., product name: JPS-9200).

For a total of 100 parts by mass of 90 parts by mass of the negative electrode active material obtained as described above and 10 parts by mass of artificial graphite having an average particle size of 5 μm, 1.4 parts by mass of carboxymethyl cellulose and styrene / butadiene latex Each 1.8 parts by mass as a solid content was mixed, and water was added as a dispersion medium to prepare a dispersion. At this time, the solid content concentration of the dispersion was 50% by mass.
The dispersion was applied on a copper foil having a thickness of 12 μm with a uniform thickness, and the step of drying the same was performed on both sides of the copper foil. Thereafter, this copper foil was roll-pressed to produce a negative electrode.

(B) Production of positive electrode Lithium cobaltate (LiCoO ₂ ) having an average particle diameter of 10 μm was used as the positive electrode active material.

2 parts by mass of graphite powder having an average particle size of 3.3 μm and 4 parts by mass of non-graphitic carbon powder having an average particle size of 0.04 μm were mixed with 100 parts by mass of the positive electrode active material to obtain a compound.
An N-methyl-2-pyrrolidone (hereinafter, also referred to as “NMP”) solution containing 6 parts by mass of polyvinylidene fluoride was added to this compound, and the compound was dispersed in this solution to prepare a dispersion. At this time, the solid content concentration of the dispersion was 60% by mass.
The dispersion was applied to a uniform thickness on an aluminum foil having a thickness of 15 μm, and the step of drying the same was performed on both sides of the aluminum foil. Then, the aluminum foil was roll-pressed to produce a positive electrode.

(C) Manufacture of nonaqueous electrolyte secondary battery The positive electrode and the negative electrode produced as described above were cut into a size of width: about 55 mm and length: 80 cm, and these were separated into a polyethylene microporous membrane having a thickness of 18 μm. (Porosity 50%, hole diameter: 0.1 μm to 1 μm) was wound in a roll shape with a diameter of about 17 mm. The wound coil was placed in an iron cylindrical can having a diameter of about 18 mm and a length of 65 mm. About 5 g of a mixture of ethylene carbonate and ethyl methyl carbonate (ethylene carbonate: ethyl methyl carbonate = 1: 3 (volume ratio)) in which LiPF ₆ was dissolved at a concentration of 1 mol / L was added to the can, and the can was sealed. A cylindrical nonaqueous electrolyte secondary battery was produced.
The results of the capacity evaluation of the battery of Example 1 are shown in Table 1.

[Example 2]
The negative electrode active material and battery of Example 2 were obtained in the same manner as in Example 1 except that 0.9 g of lithium hydroxide (LiOH) was used instead of 0.8 g of lithium carbonate (Li ₂ CO ₃ ). Obtained. Table 1 shows the results of the capacity evaluation of the battery using the negative electrode active material of Example 2.

[Example 3]
The negative electrode active material and battery of Example 3 were obtained in the same manner as in Example 1 except that 0.3 g of lithium fluoride (LiF) was used instead of 0.8 g of lithium carbonate (Li ₂ CO ₃ ). Obtained. Table 1 shows the results of the battery capacity evaluation using the negative electrode active material of Example 3.

[Example 4]
The negative electrode active material and battery of Example 4 were the same as Example 1 except that 0.5 g of lithium oxide (Li ₂ O) was used instead of 0.8 g of lithium carbonate (Li ₂ CO ₃ ). Got. Table 1 shows the results of the capacity evaluation of the battery using the negative electrode active material of Example 4.

[Example 5]
8 parts by mass of polyvinylidene fluoride are mixed with 100 parts by mass of 90 parts by mass of natural graphite having an average particle diameter of 10 μm and 10 parts by mass of artificial graphite having an average particle diameter of 5 μm, and N-methyl-2-pyrrolidone is mixed. (NMP) was added as a dispersion medium to prepare a dispersion. At this time, the solid content concentration of the dispersion was 50% by mass.
Further, a 10% by mass lithium ethoxide (C ₂ H ₅ OLi) ethanol solution was added to this dispersion to adjust the ratio of lithium ethoxide to natural graphite to 580 mass ppm.
The dispersion was applied on a copper foil having a thickness of 12 μm to a uniform thickness, and the step of drying the same was performed on both sides of the copper foil. Thereafter, this copper foil was roll-pressed to produce a negative electrode.
Except for the above, the negative electrode active material and battery of Example 5 were obtained in the same manner as in Example 1. Table 1 shows the results of capacity evaluation of the obtained battery.

[Example 6]
Instead of adding a 10% by mass lithium ethoxide (C ₂ H ₅ OLi) ethanol solution so that the ratio of lithium ethoxide to natural graphite is 580 ppm by mass, a 10% by mass lithium methoxide (CH ₃ OLi) ethanol solution is used. In addition, the negative electrode active material and battery of Example 6 were obtained by the same operation as Example 5 except that the ratio of lithium methoxide to natural graphite was 400 mass ppm. Table 1 shows the results of the capacity evaluation of the battery using the negative electrode active material of Example 6.

[Example 7]
With 10 wt% of lithium ethoxide (C ₂ H ₅ OLi) ethanol, the proportion of lithium ethoxide to natural graphite instead of 580 mass ppm, 1 mass% of lithium alkyl carbonate (C ₂ H ₅ OCO ₂ Li ) N-methyl-2-pyrrolidone solution was added, and the same procedure as in Example 5 was performed except that the ratio of lithium alkyl carbonate (C ₂ H ₅ OCO ₂ Li) to natural graphite was 450 ppm by mass. The negative electrode active material and battery of Example 7 were obtained. Table 1 shows the results of the capacity evaluation of the battery using the negative electrode active material of Example 7.

[Example 8]
The negative electrode active material and battery of Example 8 were the same as Example 1 except that 0.02 g of lithium oxide (Li ₂ O) was used instead of 0.8 g of lithium carbonate (Li ₂ CO ₃ ). Got. Table 1 shows the results of the capacity evaluation of the battery using the negative electrode active material of Example 8.

[Example 9]
Instead of adding a 10% by mass lithium ethoxide (C ₂ H ₅ OLi) ethanol solution so that the ratio of lithium ethoxide to natural graphite is 580 ppm by mass, a 10% by mass lithium methoxide (CH ₃ OLi) ethanol solution is used. A negative electrode active material and a battery of Example 9 were obtained in the same manner as in Example 5 except that 1% by mass was added to the dispersion.
Here, in particular, in Example 9, the battery was charged and discharged for one cycle. The amount of the lithium compound contained in the negative electrode active material after charge / discharge was determined using an XPS analyzer (manufactured by JEOL Ltd., product name: JPS-9200). And the ratio of the lithium compound to the substance A was calculated. The results are shown in Table 1. Table 1 shows the results of capacity evaluation of the obtained battery of Example 9 (uncharged / discharged battery).

[Example 10]
The negative electrode active material and battery of Example 10 were the same as Example 1 except that 0.06 g of lithium oxide (Li ₂ O) was used instead of 0.8 g of lithium carbonate (Li ₂ CO ₃ ). Got. Table 1 shows the results of battery capacity evaluation using the negative electrode active material of Example 10.

[Example 11]
Example 6 except that silicon (Si) having an average particle size of 5 μm was used instead of natural graphite having an average particle size of 10 μm, and the coating amount of the obtained negative electrode was 120 g / m ^{2 on} both sides. By the same operation, the negative electrode active material and battery of Example 11 were obtained. Table 1 shows the results of the battery capacity evaluation using the negative electrode active material of Example 11.

[Example 12]
A negative electrode active material and a battery of Example 12 were obtained in the same manner as in Example 6 except that Li ₄ Ti ₅ O ₁₂ having an average particle diameter of 5 μm was used instead of natural graphite having an average particle diameter of 10 μm. . Table 1 shows the results of the capacity evaluation of the battery using the negative electrode active material of Example 12.

[Comparative Example 1]
The negative electrode active material and battery of Comparative Example 1 were prepared in the same manner as in Example 1 except that 1.1 g of lithium hydroxide (LiOH) was used instead of 0.8 g of lithium carbonate (Li ₂ CO ₃ ). Obtained. Table 1 shows the results of battery capacity evaluation using the negative electrode active material of Comparative Example 1.

[Comparative Example 2]
The negative electrode active material and battery of Comparative Example 2 were prepared in the same manner as in Example 1 except that 0.005 g of lithium hydroxide (LiOH) was used instead of 0.8 g of lithium carbonate (Li ₂ CO ₃ ). Obtained. Table 1 shows the results of battery capacity evaluation using the negative electrode active material of Comparative Example 2.

[Comparative Example 3]
A negative electrode active material and a battery of Comparative Example 3 were obtained in the same manner as in Example 1, except that lithium carbonate (Li ₂ CO ₃ ) was not mixed with natural graphite having an average particle size of 10 μm. Table 1 shows the results of battery capacity evaluation using the negative electrode active material of Comparative Example 3.

[Comparative Example 4]
A negative electrode active material and a battery of Comparative Example 4 were obtained in the same manner as in Example 11, except that the 10 mass% lithium methoxide (CH ₃ OLi) ethanol solution was not added. Table 1 shows the results of battery capacity evaluation using the negative electrode active material of Comparative Example 4.

[Comparative Example 5]
A negative electrode active material and a battery of Comparative Example 5 were obtained in the same manner as in Example 12 except that the 10 mass% lithium methoxide (CH ₃ OLi) ethanol solution was not added. Table 1 shows the results of the battery capacity evaluation using the negative electrode active material of Comparative Example 5.

  The negative electrode active material for nonaqueous electrolyte secondary batteries of the present invention has industrial applicability as a negative electrode active material for nonaqueous electrolyte secondary batteries such as lithium ion secondary batteries and lithium ion capacitors. The nonaqueous electrolyte secondary battery having a negative electrode including the negative electrode active material for a nonaqueous electrolyte secondary battery of the present invention has a higher capacity than that of the conventional one.

Claims (4)

A substance A and a lithium compound contained in the substance A,
The substance A includes at least one selected from the group consisting of carbon materials, metals, metalloids, alloys, oxides, and nitrides capable of electrochemically absorbing and releasing lithium ions,
The lithium compound is selected from the group consisting of Li ₂ CO ₃ , LiOH, Li ₂ O, LiF, ROLi, and ROCO ₂ Li (R represents C _n H _{2n + 1} (n represents an integer of 1 or more)). At least one kind,
The negative electrode active material for a non-aqueous electrolyte secondary battery, wherein the ratio of the lithium compound to the substance A is 10 mass ppm or more and 1000 mass ppm or less. The substance A is a carbon material capable of electrochemically inserting and extracting lithium ions,
The at least one lithium compound is selected from the group consisting of Li ₂ CO ₃ , Li ₂ O, LiF, and ROCO ₂ Li (R represents C _n H _{2n + 1} (n represents an integer of 1 or more)). The
The negative electrode active material for nonaqueous electrolyte secondary batteries according to claim 1.   A negative electrode comprising the negative electrode active material for a non-aqueous electrolyte secondary battery according to claim 1.   A non-aqueous electrolyte secondary battery comprising the negative electrode according to claim 3.