JP6894965B2 - Negative electrode materials for lithium-ion batteries, negative electrodes for lithium-ion batteries, and lithium-ion batteries - Google Patents

Description

The present invention relates to a negative electrode material for a lithium ion battery, a negative electrode for a lithium ion battery, and a lithium ion battery.

Lithium-ion batteries are generally used as a power source for small portable devices such as mobile phones and laptop computers. Recently, in addition to small portable devices, lithium-ion batteries have begun to be used as power sources for electric vehicles and power storage.

As a negative electrode active material for a lithium ion battery, an active material mainly composed of metallic silicon is known. Since a high-capacity lithium-ion battery can be obtained as a silicon-based negative electrode active material, research is underway as an alternative to a carbon material-based negative electrode active material such as graphite (for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2012-3340

However, the silicon-based negative electrode active material has a large volume change due to charging and discharging, and its cycle characteristics are inferior to those of the carbon material-based negative electrode active material. Therefore, the silicon-based negative electrode active material is still unsatisfactory as the negative electrode active material for lithium ion batteries.

The present inventors have diligently studied to provide a silicon-based negative electrode active material having excellent cycle characteristics and discharge capacity. As a result, it was found that the sulfide solid electrolyte material containing Li, P, and S as a constituent element and the alloy material containing Li and Si as a constituent element are excellent in cycle characteristics and discharge capacity. , The present invention has been reached.

According to the present invention
A sulfide solid electrolyte containing a compound represented by Li _X P _Y S _Z (where 4 ≦ X ≦ 15, 1 ≦ Y ≦ 3, 6 ≦ Z ≦ 14, where X, Y and Z are integers). Material and
An alloy material containing the _{compound indicated by Li A} Si _B (where 7 ≦ A ≦ 25, 3 ≦ B ≦ 7; A and B are integers) and
With carbon material
Negative electrode material for lithium-ion batteries , including mechanochemical treated products of
The mechanochemical treated product contains Si fine particles having a crystallite size that cannot be detected by X-ray diffraction using CuKα ray as a radiation source.
Negative electrode materials for lithium ion batteries are provided.

Further, according to the present invention
Provided is a negative electrode for a lithium ion battery in which a negative electrode active material layer made of the negative electrode material for a lithium ion battery of the present invention is formed on the surface of a current collector.

Further, according to the present invention
A lithium ion battery including the negative electrode for a lithium ion battery, an electrolyte layer, and a positive electrode is provided.

According to the present invention, a silicon-based negative electrode material for a lithium ion battery capable of obtaining a lithium ion battery having excellent cycle characteristics and discharge capacity, a negative electrode using the negative electrode material, and a lithium ion battery having excellent cycle characteristics and discharge capacity can be obtained. Can be provided.

It is sectional drawing which shows an example of the structure of the lithium ion battery of embodiment which concerns on this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The figure is a schematic view and does not necessarily match the actual dimensional ratio. In the present embodiment, unless otherwise specified, the layer formed of the positive electrode material is referred to as a positive electrode active material layer, and the layer formed of the positive electrode active material layer on the current collector is referred to as a positive electrode. Further, the layer formed of the negative electrode material is called a negative electrode active material layer, and the layer in which the negative electrode active material layer is formed on the current collector is called a negative electrode.

[Negative electrode material for lithium-ion batteries]
First, the negative electrode material for a lithium ion battery of the present embodiment will be described.
The negative electrode material for a lithium ion battery of the present embodiment (hereinafter, also referred to as a negative electrode material) is a sulfide solid electrolyte material containing Li, P, and S as constituent elements (hereinafter, also referred to as a Li-PS-based solid electrolyte material). It is obtained by pulverizing and mixing an alloy material containing Li and Si as constituent elements (hereinafter, also referred to as a Li—Si based alloy material).

The Li-P-S-based solid electrolyte material is, for example, a compound represented by _{Li X} P _Y S _Z. Here, X is preferably 4 or more and 15 or less, more preferably 5 or more and 12 or less, and further preferably 7 or more and 11 or less. Y is preferably 1 or more and 3 or less, and more preferably 2 or more and 3 or less. Z is preferably 6 or more and 14 or less, more preferably 7 or more and 13 or less, and further preferably 9 or more and 12 or less. Specific compounds include, for example, Li ₁₀ P ₃ S _12, Li ₁₁ P ₃ S _12, Li ₁₂ P ₃ S _12, Li ₉ P ₃ S _12, Li ₇ P ₃ S _11, Li ₄ P ₂ S _{6 ,} Li ₄ P ₂ S _7, Li ₈ P ₂ S _9, Li ₇ P ₁ S _{6 and the} like.
Here, as the Li-P-S-based solid electrolyte material, for example, Li ₂ S, P ₂ S ₅ , Li ₃ N and the like are mixed at a predetermined ratio, and mixed pulverization such as mechanochemical treatment is performed. It can be manufactured by.

The Li-Si alloy material is, for example, a compound represented by _{Li A} Si _B. Here, A is preferably 7 or more and 25 or less, and more preferably 13 or more and 22 or less. B is preferably 3 or more and 7 or less, and more preferably 4 or more and 5 or less. Specific examples of the compound include Li ₂₂ Si _5, Li ₁₃ Si _4, Li ₇ Si _{3, and the} like.
The Li-Si alloy material can be produced, for example, by melting and mixing Li and Si at a predetermined ratio and then pulverizing the material.

Li-P-S-based reaction molar ratio of Li-Si-based alloy material for the solid electrolyte material, formation or crystallization of Si agglomerate due to the fact that the amount of Si fine particles increases, and Si particles Li 2 _S and Li, From the viewpoint of creating a uniformly dispersed state in a glass solid electrolyte containing P and S as main components, it is preferably 1.5 or more and 7.7 or less, and more preferably 1.9 or more and 3.7 or less.

When the negative electrode material of the present embodiment is used, the cycle characteristics of the lithium ion battery can be improved. The reason for this is not always clear, but the following reasons can be inferred.
First, _{the material obtained by pulverizing and mixing Li 11} P ₃ S ₁₂ and Li ₂₂ Si ₅ was subjected to X-ray diffraction measurement using CuKα ray as a radiation source, and it was derived from _{Li 11} P ₃ S _12. diffraction peaks from a diffraction peak and _Li 22 Si ₅ disappeared and the diffraction peak of lithium sulfide _(Li 2 S) is detected.
Since _{the peaks of Li 11} P ₃ S ₁₂ and Li ₂₂ Si ₅ have disappeared, it can be confirmed that Li ₁₁ P ₃ S ₁₂ and Li ₂₂ Si ₅ have reacted by pulverization and mixing and have been vitrified. Further, since _{the peak of Li 2} S is detected, it can be confirmed that Li ₁₁ P ₃ S ₁₂ reacts with Li ₂₂ Si ₅ to generate _{Li 2 S.}
Here, since Li ₂ S is generated by the reaction _{between Li 11} P ₃ S ₁₂ and Li ₂₂ Si ₅ , it is considered that Si is also generated at the same time, but the peak of the (111) plane of Si (111) 2θ = 28.4 ± 0.3 °) is not detected.
Therefore, an arbitrary portion φ100 μm region of the φ9.5 mm × 1 mm pellet surface obtained by press-molding the product obtained by pulverizing and mixing _{Li 11} P ₃ S ₁₂ and Li ₂₂ Si _{5 at 350 MPa was X-rayed.} When analyzed by photoelectron spectroscopy (XPS) (PHI Co. Quantera SXM) 1s orbital spectrum of Li, the bond energy of a metal Si and Li ₂ S is detected as 2p orbital spectrum of 2p orbit spectrum and Si of S. In addition, binding energies of SiOx (x <2), LiOH, Li ₂ O, etc. are detected because the pellet surface is slightly oxidized.
From this, it can be understood that the negative electrode material of the present embodiment contains Si fine particles having a crystallite size that cannot be detected by X-ray diffraction using CuKα ray as a radiation source.
From the above, the negative electrode material of the present embodiment, such Si particles Li 2 _S and Li, P, and uniformly dispersed at an appropriate ratio to the solid electrolyte comprising a compound mainly containing S, Si is very Since it is a small fine particle, it is presumed that an unprecedentedly good cycle characteristic can be realized because the volume change of the Si fine particle caused by charging and discharging is unlikely to cause poor contact with the solid electrolyte.
Here, the crystallite size that cannot be detected by X-ray diffraction using CuKα ray as a radioactive source is in the range of 0.4 nm or more and 2.0 nm or less when calculated from the following Scherrer equation.
D = 0.94λ / βcosθ
However, D is the crystallite diameter (Å), β is the half width of the X-ray diffraction peak, θ is the Bragg angle, and λ is the wavelength of the X-ray (CuKα) (1.54 Å).

The negative electrode material of the present embodiment preferably further contains a carbon material. Examples of such carbon materials include graphite materials such as natural graphite and artificial graphite; carbon black such as acetylene black and kechen black; resin carbon; carbon fiber; activated carbon; hard carbon; soft carbon; porous carbon ( For example, CNovell, manufactured by Toyo Carbon) and the like. Of these, graphitic materials are particularly preferred.
Such a carbon material functions not only as a negative electrode active material but also as a conductive auxiliary agent. Therefore, the negative electrode material of the present embodiment can further improve the charge / discharge capacity of the obtained lithium ion battery by further containing the carbon material.

The ratio of the mixed weight of the carbon material to the total weight of the Li-PS-based solid electrolyte material and the Li-Si-based alloy material is preferably 0.01 or more and 1.5 or less, and more preferably 0.05 or more. It is 0.70 or less, and more preferably 0.12 or more and 0.40 or less.

_{The carbon material of the present embodiment is not particularly limited, but the average particle size d 50} in the weight-based particle size distribution measured by the laser diffraction / scattering particle size distribution measurement method is preferably 0.02 μm or more and 30 μm or less.
By setting the average particle size d ₅₀ of the carbon material within the above range, good handleability can be maintained and a higher density negative electrode can be produced.

The negative electrode material of the present embodiment is not particularly limited, but other components may include, for example, one or more materials selected from a binder, a thickener, a solid electrolyte material, and the like.

The binder of the present embodiment is not particularly limited as long as it is an organic solvent-based binder among the binders usually used for lithium ion batteries, and examples thereof include polytetrafluoroethylene, polyvinylidene fluoride, and polyimide. These binders may be used alone or in combination of two or more.

The negative electrode material of the present embodiment is usually unnecessary because it is relatively easy to obtain viscosity when an organic solvent-based binder is used, but it may contain a thickener from the viewpoint of adjusting the fluidity of the slurry suitable for coating. Good. Examples of the thickener of the present embodiment include swellable viscous mineral scumetite and polyvinylcarboxylic acid amide. These thickeners may be used alone or in combination of two or more.

When the negative electrode material of the present embodiment is used for the negative electrode for an all-solid-state lithium-ion battery, the negative electrode material of the present embodiment preferably contains a solid electrolyte material. The solid electrolyte material of the present embodiment is not particularly limited as long as it has ionic conductivity and insulating properties, but a material generally used for an all-solid-state lithium-ion battery can be used. For example, a sulfide solid electrolyte material, an oxide solid electrolyte material, and the like can be mentioned. Among these, a sulfide solid electrolyte material is preferable. This makes it possible to obtain an all-solid-state lithium-ion battery having excellent output characteristics.

Examples of the sulfide solid electrolyte material include Li ₂ SP ₂ S ₅ material, Li ₂ S-SiS ₂ material, Li ₂ S-GeS ₂ material, Li ₂ S-Al ₂ S ₃ material, and the like. .. _{Among these, the Li 2} SP ₂ S ₅ material is preferable because it has excellent lithium ion conductivity and the manufacturing process is simple.

The blending amounts of the binder, the thickener, and the solid electrolyte material in the negative electrode material of the present embodiment are appropriately determined according to the intended use of the battery and the like, and are not particularly limited. Can be set.

[Manufacturing method of negative electrode material for lithium-ion batteries]
Subsequently, a method for producing the negative electrode material of the present embodiment will be described.
The negative electrode material of the present embodiment can be obtained by pulverizing and mixing a Li-PS-based solid electrolyte material and a Li-Si-based alloy material. Examples of the Li-PS-based solid electrolyte material and the Li-Si-based alloy material include those described above.

First, the mixing molar ratio of the Li—Si alloy material to the Li—P—S solid electrolyte material is preferably 1.5 or more and 7.7 or less, more preferably 1.9 or more and 3.7 or less. The Li-PS-based solid electrolyte material and the Li-Si-based alloy material are mixed. Here, the mixed molar ratio of the Li—Si alloy material to the Li—P—S solid electrolyte material is usually the above reaction molar ratio. Here, the mixed molar ratio of the present embodiment can be obtained by, for example, ICP emission spectroscopic analysis, but can usually be calculated from the weight ratio of the charged material.

Subsequently, the Li-PS-based solid electrolyte material and the Li-Si-based alloy material are pulverized and mixed.
As a method of pulverizing and mixing the Li-P-S-based solid electrolyte material and the Li-Si-based alloy material, any method can uniformly pulverize and mix the Li-PS-based solid electrolyte material and the Li-Si-based alloy material. The method is not particularly limited, and examples thereof include a method of performing mechanochemical treatment in a non-active atmosphere. When the mechanochemical treatment is used, the Li-P-S-based solid electrolyte material and the Li-Si-based alloy material can be mixed while being crushed into fine particles. Therefore, the Li-P-S-based solid electrolyte material and Li -The contact area with Si-based alloy materials can be increased. Thereby, the reaction between the Li-P-S-based solid electrolyte material and the Li-Si-based alloy material can be promoted.

Here, the mechanochemical treatment is a method of mixing while applying mechanical energy such as shearing force, collision force or centrifugal force to the mixing target. Examples of devices that perform crushing and mixing by mechanochemical treatment include crushing and dispersing machines such as ball mills, bead mills, and vibration mills.

The non-active atmosphere is ^{a vacuum atmosphere of 1 to 10-5} Pa or an inert gas atmosphere. Under the non-active atmosphere, the dew point is preferably −50 ° C. or lower, and more preferably −60 ° C. or lower in order to avoid contact with moisture. The above-mentioned inert gas atmosphere is an atmosphere of an inert gas such as argon gas, helium gas, and nitrogen gas. The higher the purity of these inert gases, the more preferable they are, in order to prevent impurities from being mixed into the product. The method of introducing the inert gas into the mixed system is not particularly limited as long as the inside of the mixed system is filled with the inert gas atmosphere, but a method of purging the inert gas and continuing to introduce a certain amount of the inert gas. The method etc. can be mentioned.

Conditions such as stirring speed, processing time, temperature, reaction pressure, and gravitational acceleration applied to the mixture when crushing and mixing the Li-PS solid electrolyte material and the Li-Si alloy material are the processing amount of the mixture. Can be determined as appropriate. In X-ray diffraction measurement using a CuKα ray as a radiation source, a diffraction peak of Li ₂ S (e.g., 2θ = 27.0 °) is generated, and, Li-P-S-based solid electrolyte material from the diffraction peak ( For example, in the case of Li ₁₁ P ₃ S ₁₂ , 2θ = 17.7 °) and the diffraction peak derived from the Li—Si alloy material (for example, in _{the case of Li 22} Si ₅ , 2θ = 40.8 °) are not detected. It is preferable to grind and mix until it becomes.

Then, if necessary, a carbon material is mixed with the obtained negative electrode material. The carbon material is added when the Li-PS-based solid electrolyte material and the Li-Si-based alloy material are pulverized and mixed to form the Li-PS-based solid electrolyte material and the Li-Si-based alloy material. It can also be pulverized and mixed together.
The ratio of the mixed weight of the carbon material to the total weight of the Li-PS-based solid electrolyte material and the Li-Si-based alloy material is preferably 0.01 or more and 1.5 or less, and more preferably 0.05 or more. It is 0.70 or less, more preferably 0.12 or more and 0.40 or less. When the mixing amount of the carbon material is within the above range, the charge / discharge capacity of the obtained lithium ion battery can be further improved.

Examples of the method of mixing the carbon material with the negative electrode material obtained by mixing and pulverizing the Li-P-S-based solid electrolyte material and the Li-Si-based alloy material include the above-mentioned mixing by the mechanochemical treatment.

Then, if necessary, one or more materials selected from a binder, a thickener, a solid electrolyte material, and the like are mixed. As these mixers, known ones such as a ball mill and a planetary mixer can be used, and are not particularly limited. The mixing method is not particularly limited, and the mixing method can be carried out according to a known method.

By the above procedure, the negative electrode material according to the present embodiment can be obtained.

[Negative electrode for lithium-ion battery]
Next, the negative electrode for a lithium ion battery including the negative electrode material of the present embodiment will be described.
The negative electrode for a lithium ion battery of the present embodiment is not particularly limited, but can be obtained, for example, by forming a negative electrode active material layer made of the negative electrode material of the present embodiment on the surface of a current collector such as stainless steel foil.

The thickness and density of the negative electrode for a lithium ion battery of the present embodiment are appropriately determined according to the intended use of the battery and are not particularly limited, and can be set according to generally known information.

[Manufacturing method of negative electrode for lithium ion battery]
Next, a method for manufacturing the negative electrode for a lithium ion battery of the present embodiment will be described.
The negative electrode for a lithium ion battery of the present embodiment is not particularly limited, but can be manufactured according to a generally known method. For example, the negative electrode material of the present embodiment is formed into a sheet shape, a pellet shape, or the like by compression molding, roll molding, or the like to form a negative electrode active material layer. Then, the negative electrode of the present embodiment can be obtained by laminating the negative electrode active material layer thus obtained and the current collector.
Further, a negative electrode can be manufactured by producing a negative electrode slurry using the negative electrode material of the present embodiment, applying the slurry to a current collector, and drying the slurry.

The negative electrode active material layer may be formed on only one side of the current collector or on both sides. The thickness, length and width of the negative electrode active material layer can be appropriately determined according to the size and application of the battery.

The current collector used for manufacturing the negative electrode of the present embodiment is not particularly limited, and a normal current collector such as a copper foil or a nickel foil that can be used for a lithium ion battery can be used.

The negative electrode for a lithium ion battery of the present embodiment may be pressed as necessary to adjust the density of the negative electrode. As a pressing method, a generally known method can be used.

[Lithium-ion battery]
Next, the lithium ion battery 100 of the present embodiment will be described. FIG. 1 is a cross-sectional view showing an example of the structure of the lithium ion battery according to the embodiment of the present invention.

The lithium ion battery 100 of the present embodiment includes, for example, a positive electrode 110, an electrolyte layer 120, and a negative electrode 130. The negative electrode 130 is the negative electrode for the lithium ion battery of the present embodiment.
The lithium ion battery 100 of the present embodiment is manufactured according to a generally known method. For example, a positive electrode 110, a solid electrolyte layer or a separator, and a negative electrode 130 are stacked to form a cylindrical shape, a coin shape, a square shape, a film shape, or any other shape, and if necessary, a non-aqueous electrolyte solution is sealed. It is produced by

The electrolyte layer 120 is a layer formed between the positive electrode 110 and the negative electrode 130. Examples of the electrolyte layer 120 include a separator impregnated with a non-aqueous electrolyte solution and a solid electrolyte layer containing a solid electrolyte.

The separator of the present embodiment is not particularly limited as long as it has a function of electrically insulating the positive electrode 110 and the negative electrode 130 and transmitting lithium ions, and for example, a porous membrane can be used.
As the porous film, a microporous polymer film is preferably used, and examples of the material include polyolefin, polyimide, polyvinylidene fluoride, polyester and the like. In particular, a porous polyolefin film is preferable, and specific examples thereof include a porous polyethylene film and a porous polypropylene film.

The non-aqueous electrolyte solution of the present embodiment is one in which an electrolyte is dissolved in a solvent.
Any known lithium salt can be used as the electrolyte, and it may be selected according to the type of active material. For _{example, LiClO 4, LiBF 4, LiPF} 6, LiCF 3 SO 3, LiCF 3 CO 2, LiAsF 6, LiSbF 6, LiB 10 Cl 10, LiAlCl 4, LiCl, LiBr, LiB (C 2 H 5) 4, CF 3 Examples thereof include SO ₃ Li, CH ₃ SO ₃ Li, LiCF ₃ SO _{3 , LiC 4} F ₉ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N, and lower fatty acid lithium carboxylate.

The solvent for dissolving the electrolyte is not particularly limited as long as it is usually used as a liquid for dissolving the electrolyte, and ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), and dimethyl carbonate (DMC). , Diethyl carbonate (DEC), methyl ethyl carbonate (MEC), vinylene carbonate (VC) and other solvents; γ-butyrolactone, γ-valerolactone and other lactones; trimethoxymethane, 1,2-dimethoxyethane, diethyl ether , 2-ethoxyethane, tetrahydrofuran, 2-methyl tetrahydrofuran and other ethers; dimethyl sulfoxide and other sulfoxides; 1,3-dioxolane, 4-methyl-1,3-dioxolane and other oxolanes; acetonitrile, nitromethane, formamide, Nitrogen-containing substances such as dimethylformamide; organic acid esters such as methyl formate, methyl acetate, ethyl acetate, butyl acetate, methyl propionate, ethyl propionate; phosphate triesters and jiglimes; triglimes; sulfolanes, methyl sulfolanes, etc. Sulfolans; oxazolidinones such as 3-methyl-2-oxazolidinone; sulton species such as 1,3-propanesulton, 1,4-butanesulton, naphthalusulton; and the like. These may be used individually by 1 type, or may be used in combination of 2 or more type.

The positive electrode 110 is not particularly limited, and those generally used for lithium ion batteries can be used. The positive electrode 110 is not particularly limited, but can be manufactured according to a generally known method. For example, it can be obtained by forming a positive electrode active material layer containing a positive electrode active material on the surface of a current collector such as an aluminum foil.

The thickness and density of the positive electrode active material layer 101 are appropriately determined according to the intended use of the battery and the like, and are not particularly limited, and can be set according to generally known information.

The positive electrode active material of the present embodiment is not particularly limited, and generally known materials can be used. For example, lithium cobalt oxide (LiCoO _2), lithium nickel oxide (LiNiO _2), composite oxides such as lithium manganese oxide (LiMn ₂ O _4); polyaniline, conductive polymers such as polypyrrole; _Li 2 S, Sulfides such as CuS, Li-Cu-S compounds, MoS ₂ , and Li-Mo-S compounds can be used.

The positive electrode active material layer is not particularly limited, but may contain one or more materials selected from, for example, a binder, a thickener, a conductive auxiliary agent, a solid electrolyte material, and the like as components other than the positive electrode active material of the present embodiment. Good.

The types and blending ratios of the various materials in the positive electrode active material layer are appropriately determined according to the intended use of the battery and the like, and are not particularly limited, and can be set according to generally known information.

The lithium ion battery of the present embodiment can be an all-solid-state lithium-ion battery by using a solid electrolyte material instead of the above-mentioned non-aqueous electrolyte solution as the electrolyte.
The all-solid lithium-ion battery of the present embodiment has, for example, a positive electrode 110, a negative electrode 130, and a solid electrolyte layer (electrolyte layer 120) formed of a solid electrolyte between the positive electrode 110 and the negative electrode 130.
The solid electrolyte material of the present embodiment is not particularly limited, but generally known materials can be used. For example, the same material as the solid electrolyte material contained in the negative electrode 130 described above can be used.
When the negative electrode material of the present embodiment is used as the negative electrode material of the all-solid-state lithium-ion battery, it is possible to obtain a lithium-ion battery having good battery characteristics such as charge / discharge capacity and cycle characteristics and having high safety.

Although the embodiments of the present invention have been described above, these are examples of the present invention, and various configurations other than the above can be adopted.
The present invention is not limited to the above-described embodiment, and modifications and improvements within the range in which the object of the present invention can be achieved are included in the present invention.
Hereinafter, an example of the reference form will be added.
<Additional notes>
(Appendix 1)
A sulfide solid electrolyte material containing Li, P, and S as constituent elements,
Alloy materials containing Li and Si as constituent elements
A negative electrode material for lithium-ion batteries, which is obtained by pulverizing and mixing.
(Appendix 2)
In the negative electrode material for lithium ion batteries described in Appendix 1,
The sulfide solid electrolyte material is a _{negative electrode for a lithium ion battery, which is a compound represented by Li X} P _Y S _Z (where 4 ≦ X ≦ 15, 1 ≦ Y ≦ 3, 6 ≦ Z ≦ 14). material.
(Appendix 3)
In the negative electrode material for a lithium ion battery according to Appendix 1 or 2,
The alloy material is a negative electrode material for a lithium ion battery, which is a compound represented by _{Li A} Si _{B (where 7 ≦ A ≦ 25, 3 ≦ B ≦ 7).}
(Appendix 4)
In the negative electrode material for a lithium ion battery according to any one of Appendix 1 to 3,
A negative electrode material for a lithium ion battery, wherein the reaction molar ratio of the alloy material to the sulfide solid electrolyte material is 1.5 or more and 7.7 or less.
(Appendix 5)
In the negative electrode material for a lithium ion battery according to any one of Appendix 1 to 4.
Negative electrode material for lithium-ion batteries, including carbon material.
(Appendix 6)
In the negative electrode material for lithium ion batteries described in Appendix 5,
The carbon material is a graphite material, which is a negative electrode material for a lithium ion battery.
(Appendix 7)
In the negative electrode material for a lithium ion battery according to any one of Appendix 1 to 6,
A negative electrode material for a lithium ion battery, wherein the ratio of the mixed weight of the carbon material to the total weight of the sulfide solid electrolyte material and the alloy material is 0.01 or more and 1.5 or less.
(Appendix 8)
A negative electrode material for a lithium ion battery containing Si fine particles having a crystallite size that cannot be detected by X-ray diffraction using CuKα ray as a radiation source.
(Appendix 9)
In the negative electrode material for lithium ion batteries described in Appendix 8,
Negative electrode material for lithium-ion batteries, including carbon material.
(Appendix 10)
In the negative electrode material for lithium ion batteries described in Appendix 9,
The carbon material is a graphite material, which is a negative electrode material for a lithium ion battery.
(Appendix 11)
A negative electrode for a lithium ion battery, wherein a negative electrode active material layer made of the negative electrode material for a lithium ion battery according to any one of Supplementary note 1 to 10 is formed on the surface of a current collector.
(Appendix 12)
A lithium ion battery comprising the negative electrode for a lithium ion battery according to Appendix 11, an electrolyte layer, and a positive electrode.
(Appendix 13)
In the lithium ion battery described in Appendix 12,
A lithium ion battery in which the electrolyte is a solid electrolyte.

Hereinafter, the present invention will be described with reference to Examples and Comparative Examples, but the present invention is not limited thereto. In the following Examples / Comparative Examples, "mAh / g" indicates the capacity density per 1 g of the negative electrode material.

[1] Measurement method First, the measurement methods in the following examples and comparative examples will be described.

(1) X-ray Diffraction Analysis Using an X-ray diffractometer (manufactured by Rigaku Co., Ltd., RINT2000), the diffraction spectra of the negative electrode materials obtained in Examples and Comparative Examples were obtained by X-ray diffraction analysis. In addition, CuKα ray was used as a radiation source.

(2) Charge / Discharge Test 15 mg of the negative electrode material obtained in Examples and Comparative Examples was press-molded to obtain a negative electrode (diameter φ = 14 mm, thickness t = 0.15 mm).
Next, the solid electrolyte layer (Li ₁₀ P ₃ S ₁₂ , 150 mg, diameter φ = 14 mm, thickness t = 0.6 mm), positive electrode (Li ₆ MoS ₆ : acetylene black (AB): Li ₁₀ P ₃ S ₁₂ = 1: 1: 1 (% by weight), 45 mg, diameter φ = 14 mm, thickness t = 0.15 mm) were laminated in this order to prepare an all-solid-state lithium-ion battery.
Next, the obtained all-solid-state lithium-ion battery was charged and discharged 10 times under the conditions of ^{a current value of 0.1 mA, a current density of 0.065 mA / cm 2, and a measurement potential of 0.9-3.5 V.} The results obtained are shown in Table 1. Here, the 10th discharge capacity when the 1st discharge capacity is 100% is defined as the discharge capacity change rate [%].

_{Here, Li 6} MoS _6, which is a positive electrode active material, was produced by the following procedure.
Under an argon atmosphere, MoS ₂ (manufactured by Wako Pure Chemical Industries, Ltd., 970 mg, 6.1 mmol), Li ₂ S (manufactured by Sigma-Aldrich Japan, 835 mg, 17.8 mmol), and S (manufactured by Sigma-Aldrich Japan, 194 mg). , 6.1 mmol) was placed in an alumina ball mill pot (internal volume 400 ml) and treated at 97 rpm for 4 days.

_{Further, Li 10} P ₃ S _{12, which} is a Li-P-S-based solid electrolyte material, was produced by the following procedure.
As raw materials, Li ₂ S (manufactured by Alfa Aesar, purity 99.9%) and P ₂ S ₅ (reagent manufactured by Kanto Chemical Co., Inc.) were used. Li ₃ N was prepared by the following procedure.
First, in a glove box with a nitrogen atmosphere, a stainless steel swordsman was used for Li foil (purity 99.8%, thickness 0.5 mm, manufactured by Honjo Metal Co., Ltd.) to make many holes of φ1 mm or less. The Li foil began to change to black-purple from the hole portion, and when left as it was at room temperature for 24 hours, all of the Li foil changed to _{black-purple Li 3 N.} Li ₃ N was pulverized in an agate mortar and then sieved with a stainless steel sieve, and a powder of 75 μm or less was recovered and used as a raw material for a solid electrolyte material.
Next, each raw material was precisely weighed in an argon glove box so that Li ₂ S: P ₂ S ₅ : Li ₃ N = 71.1: 23.7: 5.3 (mol%), and these powders were added. The mixture was mixed in an agate mortar for 20 minutes. Next, 2 g of the mixed powder was weighed and mixed and pulverized at 100 rpm for 1 hour with a planetary ball mill (Fritsch, P-7) together with 500 g of zirconia balls having a diameter of 10 mm. Then, it was mixed and pulverized at 400 rpm for 15 hours. The powder after mixing and crushing was pressed at 270 MPa for 10 minutes using a press device to obtain a plate-shaped mixture having a thickness of 0.6 mm. The obtained mixture was placed in a carbon boat and heat-treated in an argon air stream at 300 ° C. for 2 hours to obtain a solid electrolyte material having _{a Li 10} P ₃ S _{12 composition, in which the powders were fused to each other and hard-sintered.}

[2] Production of Negative Electrode Material <Example 1>
In an argon atmosphere, Li foil (manufactured by Honjo Metal Co., Ltd., 1.04 g) and Si powder (manufactured by Furukawa Co., Ltd., 0.96 g) were melt-mixed at 300 ° C. for 1 hour in a zirconium crucible. Next, the mixture was placed in an alumina ball mill pot, further ZrO ₂ balls were placed, and the alumina ball mill pot was sealed. Next, an alumina ball mill pot was treated at 97 rpm for 27 hours to obtain a Li-Si alloy 1 having _{a Li 22} Si _{5 composition.}

_{In addition, Li 11} P ₃ S ₁₂ , which is a Li-P-S-based solid electrolyte material, was prepared by the following procedure.
As the raw material, the same material as in the preparation of the solid electrolyte material having the composition of _{Li 10} P ₃ S _{12 was used.}
First, each raw material is precisely weighed in an argon glove box so that Li ₂ S: P ₂ S ₅ : Li ₃ N = 67.5: 22.5: 10.0 (mol%), and these powders are 20 Mix in agate mortar for minutes. Next, 2 g of the mixed powder was weighed and mixed and pulverized at 100 rpm for 1 hour with a planetary ball mill (Fritsch, P-7) together with 500 g of zirconia balls having a diameter of 10 mm. Then, it was mixed and pulverized at 400 rpm for 15 hours. The powder after mixing and crushing was placed in a carbon boat and heat-treated in an argon air stream at 300 ° C. for 2 hours to obtain a Li-PS-based solid electrolyte material 1 having _{a Li 11} P ₃ S _{12 composition.}

Next, in the argon glove box, each raw material is subjected to Li-Si alloy 1: Li-PS-based solid electrolyte material 1: graphite (CGC-20, manufactured by Nippon Graphite Industry Co., Ltd., average particle size d ₅₀ : 21.7 μm) = The mixture was precisely weighed to a ratio of 4: 3: 8 (weight ratio), and these were mixed in an agate mortar for 10 minutes. Next, 1.0 g of the mixed powder was weighed, and these were placed in an alumina ball mill pot (internal volume 400 mL) together with 500 g of zirconia balls having a diameter of 10 mm, and mixed and pulverized at 97 rpm for 24 hours to obtain a negative electrode material 1.
When the X-ray diffraction spectrum of the obtained negative electrode material 1 was measured, the diffraction peaks of _{Li 11} P ₃ S _{12 which is a Li-PS-based solid electrolyte material 1 and Li 22} Si ₅ which is a Li-Si alloy 1 were found. lost, the diffraction peak of Li 2 _S and graphite was detected. Moreover, the diffraction peak of Si was not detected. On the other hand, it was confirmed by X-ray photoelectron spectroscopy (XPS) (QuantaraSXM manufactured by PHI) that Si was generated.

<Example 2>
Li-Si alloy 1: Li-PS-based solid electrolyte material 1: Graphite (CGC-20, manufactured by Nippon Graphite Industry Co., Ltd.) = 4: 3: 4 (weight ratio), except that it is the same as in Example 1. , Negative electrode material 2 was obtained.
When the X-ray diffraction spectrum of the obtained negative electrode material 2 was measured, the diffraction peaks of _{Li 11} P ₃ S _{12 which is a Li-PS-based solid electrolyte material 1 and Li 22} Si ₅ which is a Li-Si alloy 1 were found. lost, the diffraction peak of Li 2 _S and graphite was detected. Moreover, the diffraction peak of Si was not detected. On the other hand, it was confirmed by XPS that Si was generated.

<Example 3>
Li-Si alloy 1: Li-PS-based solid electrolyte material 1: Graphite (CGC-20, manufactured by Nippon Graphite Industry Co., Ltd.) = 4: 3: 2 (weight ratio), except that the same as in Example 1. , Negative electrode material 3 was obtained.
When the X-ray diffraction spectrum of the obtained negative electrode material 3 was measured, the diffraction peaks of _{Li 11} P ₃ S _{12 which is a Li-PS-based solid electrolyte material 1 and Li 22} Si ₅ which is a Li-Si alloy 1 were found. lost, the diffraction peak of Li 2 _S and graphite was detected. Moreover, the diffraction peak of Si was not detected. On the other hand, it was confirmed by XPS that Si was generated.

<Example 4>
Li-Si alloy 1: Li-PS-based solid electrolyte material 1: Graphite (CGC-20, manufactured by Nippon Graphite Industry Co., Ltd.) = 4: 3: 0 (weight ratio), except that it is the same as in Example 1. , Negative electrode material 4 was obtained.
When the X-ray diffraction spectrum of the obtained negative electrode material 4 was measured, the diffraction peaks of _{Li 11} P ₃ S _{12 which is a Li-PS-based solid electrolyte material 1 and Li 22} Si ₅ which is a Li-Si alloy 1 were found. lost, the diffraction peak of Li ₂ S was detected. Moreover, the diffraction peak of Si was not detected. On the other hand, it was confirmed by XPS that Si was generated.

<Example 5>
Same as in Example 1 except _{that activated carbon (Kuraraycol YP-17, manufactured by Kuraray Chemical Co., Ltd., average particle size d 50} : 21.7 μm) was used instead of graphite (CGC-20, manufactured by Nippon Graphite Industry Co., Ltd.). , Negative electrode material 5 was obtained.
When the X-ray diffraction spectrum of the obtained negative electrode material 5 was measured, the diffraction peaks of _{Li 11} P ₃ S _{12 which is a Li-PS-based solid electrolyte material 1 and Li 22} Si ₅ which is a Li-Si alloy 1 were found. lost, the diffraction peak of Li ₂ S was detected. Moreover, the diffraction peak of Si was not detected. On the other hand, it was confirmed by XPS that Si was generated.

<Example 6>
_{The same as in Example 3 except that acetylene black (manufactured by Electrochemical Industry, average particle size d 50} : 0.04 μm) was used instead of graphite (CGC-20, manufactured by Nippon Graphite Industry Co., Ltd.), and the negative electrode material 6 was used. Obtained.
When the X-ray diffraction spectrum of the obtained negative electrode material 6 was measured, the diffraction peaks of _{Li 11} P ₃ S _{12 which is a Li-PS-based solid electrolyte material 1 and Li 22} Si ₅ which is a Li-Si alloy 1 were found. lost, the diffraction peak of Li ₂ S was detected. Moreover, the diffraction peak of Si was not detected. On the other hand, it was confirmed by XPS that Si was generated.

<Example 7>
Same as in Example 3 except that porous carbon (CNovel2200, manufactured by Toyo Tanso Co., Ltd., average particle size d ₅₀ : 9.5 μm) was used instead of graphite (CGC-20, manufactured by Nippon Graphite Industry Co., Ltd.), and the negative electrode. Material 7 was obtained.
When the X-ray diffraction spectrum of the obtained negative electrode material 7 was measured, the diffraction peaks of _{Li 11} P ₃ S _{12 which is a Li-PS-based solid electrolyte material 1 and Li 22} Si ₅ which is a Li-Si alloy 1 were found. lost, the diffraction peak of Li ₂ S was detected. Moreover, the diffraction peak of Si was not detected. On the other hand, it was confirmed by XPS that Si was generated.

<Example 8>
A negative electrode material 8 was obtained in the same manner as in Example 3 except that _{Li 7} Si ₃ was used instead of the Li-Si alloy 1.
When the X-ray diffraction spectrum of the obtained negative electrode material 8 was measured, the diffraction peaks of _{Li 11} P ₃ S ₁₂ and Li ₇ Si _{3 which are Li-P-S-based solid electrolyte materials 1 disappeared, and Li 2} S A diffraction peak was detected. Moreover, the diffraction peak of Si was not detected. On the other hand, it was confirmed by XPS that Si was generated.

<Comparative example 1>
Li-Si alloy 1: Li-PS-based solid electrolyte material 1: Graphite (CGC-20, manufactured by Nippon Graphite Industry Co., Ltd.) = 0: 3: 8 (weight ratio), except that it is the same as in Example 1. , Negative electrode material 9 was obtained.

<Comparative example 2>
Each raw material is precisely weighed in an argon glove box so that Li-Si alloy 1: sulfur (S, manufactured by Sigma-Aldrich Japan) = 1: 1.2 (weight ratio), and these are mixed in an agate mortar for 10 minutes. did. Next, 2 g of the mixed powder was precisely weighed, placed in an alumina ball mill pot (internal volume 400 mL) together with a φ10 mm zirconia ball, mixed and pulverized at 97 rpm for 24 hours, and the powder after the mixed pulverization was Li by X-ray diffraction. ₂ diffraction peaks of _S and Si was detected, it was confirmed that changes to a mixture of Li 2 _S and Si. The Li 2 except that a mixture of _S and Si was used in place of Li-Si alloy 1 in the same manner as in Example 1 to obtain a negative electrode material 10. However, the weight of Si contained in the negative electrode material is 46% of that of Example 1.
When the X-ray diffraction spectrum of the obtained negative electrode material 10 was measured, the diffraction peaks of _{Li 11} P ₃ S ₁₂ and Li ₂₂ Si _{5 , which are Li-PS-based solid electrolyte materials 1, disappeared, and Li 2} S and Li 2 S and Li 22 Si 5 disappeared. Diffraction peaks of graphite were detected. Moreover, the diffraction peak of Si was detected. The crystallite size calculated from the diffraction peak of Si using Scherrer's equation was 370 nm.

<Comparative example 3>
A negative electrode material 11 was obtained in the same manner as in Example 1 except that Si powder (manufactured by Furukawa Co., Ltd., average particle size D _{50: 2.0 μm) was used instead of the Li-Si alloy 1.}
When the X-ray diffraction spectrum of the obtained negative electrode material 11 was measured _{, the diffraction peak of Li 11} P ₃ S ₁₂ which is the Li-PS-based solid electrolyte material 1 disappeared, and the diffraction peaks of Si and graphite were detected. It was.

(Charge / discharge test results)
Table 1 shows the charge / discharge test results of the above negative electrode materials 1 to 11.
The negative electrode materials 1 to 8 obtained in the examples were superior in the discharge capacity change rate and the discharge capacity as compared with the negative electrode materials 9 to 11 obtained in the comparative examples.

100 Lithium-ion battery 110 Positive electrode 120 Electrolyte layer 130 Negative electrode

Claims (12)

A sulfide solid electrolyte containing a compound represented by Li _X P _Y S _Z (where 4 ≦ X ≦ 15, 1 ≦ Y ≦ 3, 6 ≦ Z ≦ 14, where X, Y and Z are integers). Material and
An alloy material containing the _{compound indicated by Li A} Si _B (where 7 ≦ A ≦ 25, 3 ≦ B ≦ 7; A and B are integers) and
With carbon material
Including the mechanochemical treatment product, a negative electrode material for lithium ion batteries,
The mechanochemical treated product contains Si fine particles having a crystallite size that cannot be detected by X-ray diffraction using CuKα ray as a radiation source.
Negative electrode material for lithium-ion batteries. In the negative electrode material for a lithium ion battery according to claim 1,
A negative electrode material for a lithium ion battery, wherein the mixed molar ratio of the alloy material to the sulfide solid electrolyte material is 1.5 or more and 7.7 or less. In the negative electrode material for a lithium ion battery according to claim 1 or 2.
The carbon material is a graphite material, which is a negative electrode material for a lithium ion battery. The negative electrode material for a lithium ion battery according to any one of claims 1 to 3.
A negative electrode material for a lithium ion battery, wherein the ratio of the mixed weight of the carbon material to the total weight of the sulfide solid electrolyte material and the alloy material is 0.01 or more and 1.5 or less. The negative electrode material for a lithium ion battery according to any one of claims 1 to 4.
A negative electrode material for a lithium ion battery, which is calculated from the following Scherrer equation and has a crystallite size of the Si fine particles in the range of 0.4 nm or more and 2.0 nm or less.
D = 0.94λ / βcosθ
(However, D is the crystallite diameter (Å), β is the half width of the X-ray diffraction peak, θ is the Bragg angle, and λ is the wavelength of the X-ray (CuKα) (1.54 Å).) A negative electrode for a lithium ion battery, wherein a negative electrode active material layer made of the negative electrode material for a lithium ion battery according to any one of claims 1 to 5 is formed on the surface of a current collector. A lithium ion battery comprising the negative electrode for a lithium ion battery according to claim 6, an electrolyte layer, and a positive electrode. In the lithium ion battery according to claim 7.
A lithium ion battery in which the electrolyte layer is a solid electrolyte layer. A manufacturing method for manufacturing negative electrode materials for lithium-ion batteries.
A sulfide solid electrolyte containing a compound represented by Li _X P _Y S _Z (where 4 ≦ X ≦ 15, 1 ≦ Y ≦ 3, 6 ≦ Z ≦ 14, where X, Y and Z are integers). The material, an alloy material containing a compound represented by Li _A Si _B (where 7 ≦ A ≦ 25, 3 ≦ B ≦ 7, A and B are integers), and a carbon material are mechanochemicals. A method for producing a negative electrode material for a lithium ion battery, which comprises a processing step. In the method for manufacturing a negative electrode material for a lithium ion battery according to claim 9.
A method for producing a negative electrode material for a lithium ion battery, wherein the mixed molar ratio of the alloy material to the sulfide solid electrolyte material is 1.5 or more and 7.7 or less. In the method for producing a negative electrode material for a lithium ion battery according to claim 9 or 10.
A method for producing a negative electrode material for a lithium ion battery, wherein the carbon material is a graphitic material. In the method for producing a negative electrode material for a lithium ion battery according to any one of claims 9 to 11.
A method for producing a negative electrode material for a lithium ion battery, wherein the ratio of the mixed weight of the carbon material to the total weight of the sulfide solid electrolyte material and the alloy material is 0.01 or more and 1.5 or less.

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